Sample records for mercury hydrides

  1. Study of the simultaneous determination of trace arsenic and mercury by flow injection/hydride generation/ICP-AES

    SciTech Connect

    Yu Xin; Liao Zhenhuan; Jiang Zucheng [Wuhan Univ. (China). Chemistry Dept.; Chen Jianguo; Wang Songqin [Ningbo Import and Export Commodity Inspection Bureau (China)

    1999-07-01

    It is well known that both As and Hg are toxic elements. A combined system of flow injection/hydride generation coupled with multichannel plasma spectrometer was put forward and applied to the simultaneous determination of trace arsenic and mercury. The interface between flow injection hydride generation (FI-HG) and ICP-AES, gas/liquid separator and main experimental parameters were described. The detection limits of the proposed method could be achieved to 0.x {micro}g/L level; the RSD 1.4% and 1.3% at 10 ng/mL levels of As and Hg respectively. The frequency of sampling was 150/h with 80{micro}L sampling volume. The proposed method has been applied to the simultaneous determination of As and Hg in some real samples.

  2. Mercury

    MedlinePLUS

    ... air, ingesting contaminated water and food, and having dental and medical treatments. Mercury, at high levels, may damage the ... burn mercury-containing fuels. Release of mercury from dental work and medical treatments. Breathing contaminated workplace air or skin contact ...

  3. Mercury

    NSDL National Science Digital Library

    This lithograph shows mosaic images of Mercury, captured by the Mariner 10 spacecraft. The images are accompanied by a brief description and history, some statistical facts, and a list of significant dates in the exploration of Mercury.

  4. Mercury

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.; Scott, E. R. D.

    2003-12-01

    Mercury is an important part of the solar system puzzle, yet we know less about it than any other planet, except Pluto. Mercury is the smallest of the terrestrial planets (0.05 Earth masses) and the closest to the Sun. Its relatively high density (5.4 g cm -3) indicates that it has a large metallic core (˜3/4 of the planet's radius) compared to its silicate mantle and crust. The existence of a magnetic field implies that the metallic core is still partly molten. The surface is heavily cratered like the highlands of the Moon, but some areas are smooth and less cratered, possibly like the lunar maria (but not as dark). Its surface composition, as explained in the next section, appears to be low in FeO (only ˜3 wt.%), which implies that either its crust is anorthositic (Jeanloz et al., 1995) or its mantle is similarly low in FeO ( Robinson and Taylor, 2001).The proximity of Mercury to the Sun is particularly important. In one somewhat outmoded view of how the solar system formed, Mercury was assembled in the hottest region close to the Sun so that virtually all of the iron was in the metallic state, rather than oxidized to FeO (e.g., Lewis, 1972, 1974). If correct, Mercury ought to have relatively a low content of FeO. This hypothesis also predicts that Mercury should have high concentrations of refractory elements, such as calcium, aluminum, and thorium, and low concentrations of volatile elements, such as sodium and potassium, compared to the other terrestrial planets.Alternative hypotheses tell a much more nomadic and dramatic story of Mercury's birth. In one alternative view, wandering planetesimals that might have come from as far away as Mars or the inner asteroid belt accreted to form Mercury (Wetherill, 1994). This model predicts higher FeO and volatile elements than does the high-temperature model, and similar compositions among the terrestrial planets. The accretion process might have been accompanied by a monumental impact that stripped away much of the young planet's rocky mantle, accounting for the high density of the planet ( Benz et al., 1988). Most planetary scientists consider such a giant impact as the most likely hypothesis for the origin of the Moon. A giant impact model could explain the high density of Mercury if much of the silicate material failed to reaccrete, but it would not explain the low FeO concentration of the planet. Thus, knowing the composition of Mercury is crucial to testing models of planetary accretion.In this chapter we summarize what we know about the chemical composition of Mercury, with emphasis on assessing the amount of FeO in the bulk planet. FeO is a particularly useful quantity to evaluate the extent to which Mercury is enriched in refractory elements, because its concentration increases with decreasing temperature in a cooling gas of solar composition (e.g., Goettel, 1988). We then examine models for the composition of Mercury and outline tests that future orbital missions to Mercury will be able to make.

  5. Early Diagenesis of Mercury in the Laurentian Great Lakes

    Microsoft Academic Search

    Jane M. Matty; David T. Long

    1995-01-01

    The early diagenesis of mercury in deep lake environments was investigated by examining the distribution of mercury among waters and sediments from several depositional basins in the Laurentian Great Lakes. Partitioning of mercury among different sediment phases was examined by sequential chemical extraction (using procedures specifically designed for mercury). Mercury in porewaters and sediment extracts was analyzed by flow-injection\\/hydride-generation atomic

  6. Hydride compositions

    DOEpatents

    Lee, Myung, W.

    1994-01-01

    Disclosed are a composition for use in storing hydrogen and a method for making the composition. The composition comprises a mixture of two or more hydrides, each hydride having a different series of hydrogen sorption isotherms that contribute to the overall isotherms of the mixture. The hydrides are chosen so that the isotherms of the mixture have regions wherein the H equilibrium pressure increases with increasing hydrogen, preferably linearly. The isotherms of the mixture can be adjusted by selecting hydrides with different isotherms and by varying the amounts of the individual hydrides, or both. Preferably, the mixture is made up of hydrides that have isotherms with substantially flat plateaus and in nearly equimolar amounts. The composition is activated by degassing, exposing to H, and then heating below the softening temperature of any of the constituents. When the composition is used to store hydrogen, its hydrogen content can be found simply by measuring P{sub H}{sub 2} and determining H/M from the isothermic function of the composition.

  7. Hysteresis in Metal Hydrides.

    ERIC Educational Resources Information Center

    Flanagan, Ted B., And Others

    1987-01-01

    This paper describes a reproducible process where the irreversibility can be readily evaluated and provides a thermodynamic description of the important phenomenon of hysteresis. A metal hydride is used because hysteresis is observed during the formation and decomposition of the hydride phase. (RH)

  8. Regenerative Hydride Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  9. Millimeter-Wave Spectroscopy of Ethylmercury Hydride

    NASA Astrophysics Data System (ADS)

    Goubet, M.; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2012-06-01

    The first millimeter-wave rotational spectrum of an organomercury compound, ethylmercury hydride (CH_3CH_2HgH), has been recorded using the Lille fast-scan spectrometer in the frequency range 120 -- 180 GHz. The spectroscopic study is complemented by quantum chemical calculations taking into account relativistic effects on the mercury atom. The very good agreement between theoretical and experimental molecular parameters validates the chosen ab initio method, in particular its capability to predict the accurate values of the quartic centrifugal distortion constants related to this type of compound. Estimations of the nuclear quadrupole coupling constants are not as predictive as the structural parameters but good enough to satisfy the spectroscopic needs. In addition, the orientation of the H--Hg--C bonds axis deduced from the experimental nuclear quadrupole coupling constants compares well with the corresponding ab initio value. From the good agreement between experimental and theoretical results, together with the observation of the six most abundant isotopes of mercury, ethylmercury hydride is unambiguously identified and its calculated equilibrium geometry is confirmed. Alekseev, E.A. et al. Radio Physics and Radio Astronomy 3 (2012) 78.

  10. Photochromism in yttrium hydride

    NASA Astrophysics Data System (ADS)

    Ohmura, Ayako; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Nakano, Satoshi; Takemura, K.

    2007-10-01

    Transparent orange yttrium hydride turns to black when illuminated by visible laser light at pressures of several gigapascals at room temperature. The marked reduction in optical transmittance extends over the infrared region, suggesting that illumination creates persistent free carriers. The opaque black sample returns to the transparent orange hydride during room-temperature annealing for a few hours. Photochromism is pronounced for the coexistent state of the metallic fcc-YH2 and the insulating hexagonal-YH3 state but is depressed for the single phase of hexagonal-YH3. The results indicate that light illumination can modify the optical and possibly electronic properties during a certain period of times.

  11. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, R.K.; Bystroff, R.I.; Miller, D.E.

    1986-08-27

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  12. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, Richard K. (Pleasanton, CA); Bystroff, Roman I. (Livermore, CA); Miller, Dale E. (Livermore, CA)

    1987-01-01

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  13. Thermal properties of yttrium hydride

    NASA Astrophysics Data System (ADS)

    Ito, Masato; Matsunaga, Junji; Setoyama, Daigo; Muta, Hiroaki; Kurosaki, Ken; Uno, Masayoshi; Yamanaka, Shinsuke

    2005-09-01

    The thermal properties of ?-phase yttrium hydrides (YH x: x = 1.72-2.00) were studied in the temperature range from 300 to 773 K. The heat capacities of yttrium hydrides are larger than that of yttrium metal because of hydrogen optical vibration. The thermal conductivities of the yttrium hydrides are larger than that of metal and have strong dependence on temperature. They are not markedly influenced by the hydrogen content.

  14. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

    1980-01-21

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  15. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, Moshe (Haifa, IL); Gruen, Dieter M. (Downers Grove, IL); Mendelsohn, Marshall H. (Woodridge, IL); Sheft, Irving (Oak Park, IL)

    1981-01-01

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  16. Superstoichiometric hydride of zirconium

    SciTech Connect

    Kupryazhkin, A.Ya.; Shchepetkin, A.A.; Zabolotskaya, E.V.; Pletnev, R.N.; Alyamovskii, S.I.; Kitaev, G.A.

    1987-12-01

    Superstoichiometric hydrides of zirconium have been obtained all the way up to the composition ZrH/sub 2.4/ by additional hydrogenation of ZrH/sub 2/ as a result of redistribution of hydrogen atoms between t- and o-positions. In the preparation of the hydrides the authors used zirconium iodide with an impurity content no greater than 10/sup -2/ to 10/sup -2/ mole %; the hydrogen and helium used in this work had a minimum purity of 99.95%. The content of hydrogen in the specimens was determined by a volumetric method. The x-ray diffraction analysis was performed in a DRON-2.0 unit (CuK/sub ..cap alpha../ radiation). PMR spectra were recorded in a broad-line spectrometer in the temperature interval 150-450 K.

  17. 17. VIEW OF HYDRIDING SYSTEM IN BUILDING 881. THE HYDRIDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. VIEW OF HYDRIDING SYSTEM IN BUILDING 881. THE HYDRIDING SYSTEM WAS PART OF THE FAST ENRICHED URANIUM RECOVERY PROCESS. (11/11/59) - Rocky Flats Plant, General Manufacturing, Support, Records-Central Computing, Southern portion of Plant, Golden, Jefferson County, CO

  18. Hydrogenation using hydrides and acid

    DOEpatents

    Bullock, R. Morris (Wading River, NY)

    1990-10-30

    A process for the non-catalytic hydrogenation of organic compounds, which contain at least one reducible functional group, which comprises reacting the organic compound, a hydride complex, preferably a transition metal hydride complex or an organosilane, and a strong acid in a liquid phase.

  19. Dimensionally stable metallic hydride composition

    DOEpatents

    Heung, Leung K. (Aiken, SC)

    1994-01-01

    A stable, metallic hydride composition and a process for making such a composition. The composition comprises a uniformly blended mixture of a metal hydride, kieselguhr, and a ballast metal, all in the form of particles. The composition is made by subjecting a metal hydride to one or more hydrogen absorption/desorption cycles to disintegrate the hydride particles to less than approximately 100 microns in size. The particles are partly oxidized, then blended with the ballast metal and the kieselguhr to form a uniform mixture. The mixture is compressed into pellets and calcined. Preferably, the mixture includes approximately 10 vol. % or more kieselguhr and approximately 50 vol. % or more ballast. Metal hydrides that can be used in the composition include Zr, Ti, V, Nb, Pd, as well as binary, tertiary, and more complex alloys of La, Al, Cu, Ti, Co, Ni, Fe, Zr, Mg, Ca, Mn, and mixtures and other combinations thereof. Ballast metals include Al, Cu and Ni.

  20. REMOVAL OF MERCURY FROM COAL-DERIVED SYNTHESIS GAS

    SciTech Connect

    Tom Barton

    2006-03-01

    The reduction of mercury emission from fossil fuel applications is an increasing priority for the US power industry due to regulatory pressure. While mercury removal during combustion is well studied, mercury removal in gasification is less so. The increasing application of coal gasification in future plant designs supplies the incentive for more study of mercury removal gasification processes. In gasification where the mercury is expected to be elemental, activated carbon injection has been the most effective method of mercury removal. Absorption of elemental mercury at high temperature has not been shown to be effective. The carbon is best injected downstream where the temperature has moderated and an independent collector can be established. Experiments have been conducted at 400 F to compare mercury absorption on activated carbon as received and ''super'' activated carbon. The ''super'' activated carbon was prepared by soaking the carbon in 6M nitric acid followed by neutralization and washing. Each absorption experiment has been run for 16 hours of exposure time to the gasifier product stream. The carbon samples were tested for mercury absorption by ICP hydride generation. The two carbon samples which had been washed in nitric acid then exposed to the gasifier slipstream showed higher concentrations of mercury even at this elevated absorption temperature when compared to the as received activated carbon.

  1. Hydrogen recovery with metal hydrides

    SciTech Connect

    Santangelo, J.G.; Chen, G.T.

    1982-03-01

    Air Products pursued hydride technology because hydrides first came to our attention as a unique technology which could safely store hydrogen. The preliminary economics for using available hydrides to store hydrogen in motor vehicles were not encouraging at that time. However, the possibilities for using hydrides to selectively separate hydrogen from other components occurred to us. The authors obtained a DOE contract to study metal alloys which could be used to effectively store hydrogen fuel in motor vehicles, an interest of DOE at that time. They concurrently continued independent studies on the use of hydrides for hydrogen separation. It became obvious during initial stages, that to develop hydride technology would require a partner with metallurgical background and facilities. They teamed up with MPD Technology, a wholly owned subsidiary of International Nickel. This joint R and D program has been in progress for the past three years. During this time it has taken this technology from a laboratory curiosity to a successful pilot unit currently operating at Air Products' New Orleans ammonia plant where it is selectively removing hydrogen from the ammonia purge gas stream.

  2. Hydride reorientation in Zircaloy-4 cladding

    NASA Astrophysics Data System (ADS)

    Chu, H. C.; Wu, S. K.; Kuo, R. C.

    2008-02-01

    The formation of radial hydrides in stress-relief annealed Zircaloy-4 cladding was studied. Specimens were firstly hydrided to different target hydrogen levels from 100 to 600 wt ppm and then thermally cycled in an autoclave under a constant hoop stress to form radial hydrides by a hydride reorientation process. The effect of thermal cycling on the hydride reorientation was more significant than that of isothermal treatment. Based on the experimental data, a thermodynamic model was proposed to elucidate the stress reorientation behavior of hydrides in Zircaloy cladding. According to the model, the bounds of stress and temperature to stress reorientation of hydride precipitates were developed. The threshold stress for hydrides to reorientation was a function of solution temperature and specimen hydrogen concentration.

  3. Dissolved Gaseous Mercury Concentrations and Mercury

    E-print Network

    O'Driscoll, Nelson

    % of total annual mercury inputs to the system, and studies on the Great Lakes (Canada-United States) showDissolved Gaseous Mercury Concentrations and Mercury Volatilization in a Frozen Freshwater Fluvial to examine dissolved gaseous mercury (DGM), mercury volatilization, and sediment interactions in a frozen

  4. Gas-phase acidities of binary hydrides.

    NASA Technical Reports Server (NTRS)

    Brauman, J. I.; Eyler, J. R.; Blair, L. K.; White, M. J.; Comisarow, M. B.; Smyth, K. C.

    1971-01-01

    The preferred direction of proton transfer in a reaction between a hydride molecule and a hydride ion was studied in order to determine the relative acidities of some binary hydrides. Sufficient data are presented to make clear the periodic trends in acidities and the underlying trends in other fundamental thermochemical quantities which influence acidity. The bond dissociation energies and electron affinities of the hydrides considered are listed in a table.

  5. Vanadium hydride deuterium-tritium generator

    DOEpatents

    Christensen, Leslie D. (Livermore, CA)

    1982-01-01

    A pressure controlled vanadium hydride gas generator to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

  6. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  7. Determination of mercury in fish tissue using a minianalyzer based on cold vapor atomic absorption spectrometry at the 184.9 nm line.

    PubMed

    Rizea, Maria-Cristina; Bratu, Maria-Cristina; Danet, Andrei Florin; Bratu, Adrian

    2007-09-01

    A sensitive method was proposed and optimized for the determination of total mercury in fish tissue by using wet digestion, followed by cold vapor atomic absorption spectrometry (CVAAS) at the main resonance line of mercury (184.9 nm). The measurements were made using a new type of a non-dispersive mercury minianalyzer. This instrument was initially designed and built for atmospheric mercury-vapor detection. For determining mercury in aqueous samples, the minianalyzer was linked with a mercury/hydride system, Perkin Elmer Model MHS-10. To check the method, the analyzed samples were spiked with a standard solution of mercury. The recoveries of mercury spiked to wet fish tissue were >90% for 0.5 - 0.8 g samples. The results showed a better sensitivity (about 2.5 times higher) when using the mercury absorption line at 184.9 nm compared with the sensitivity obtained by conventional CVAAS at 253.7 nm. PMID:17878589

  8. HYDRIDE BED\\/FUELCELL PROJECT

    Microsoft Academic Search

    G. Cook Story

    2000-01-01

    The Hydride Bed\\/Fuelcell Project will result in the development and production of a prototype Fuelcell Powerplant for Mining\\/Tunneling Locomotives. This powerplant will replace and outperform batteries, currently utilized for mining and tunneling. The Mine Locomotive Project is a project of the Fuelcell Propulsion Institute (FCPI) consortium.

  9. Cheaper Hydride-Forming Cathodes

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Blue, Gary

    1990-01-01

    Hydride-forming cathodes for electrochemical experiments made of materials or combinations of materials cheaper and more abundant than pure palladium, according to proposal. Concept prompted by needs of experimenters in now-discredited concept of electrochemical nuclear fusion, cathodes useful in other electrochemical applications involving generation or storage of hydrogen, deuterium, or tritium.

  10. Properties of nanoscale metal hydrides.

    PubMed

    Fichtner, Maximilian

    2009-05-20

    Nanoscale hydride particles may exhibit chemical stabilities which differ from those of a macroscopic system. The stabilities are mainly influenced by a surface energy term which contains size-dependent values of the surface tension, the molar volume and an additional term which takes into account a potential reduction of the excess surface energy. Thus, the equilibrium of a nanoparticular hydride system may be shifted to the hydrogenated or to the dehydrogenated side, depending on the size and on the prefix of the surface energy term of the hydrogenated and dehydrogenated material. Additional complexity appears when solid-state reactions of complex hydrides are considered and phase segregation has to be taken into account. In such a case the reversibility of complex hydrides may be reduced if the nanoparticles are free standing on a surface. However, it may be enhanced if the system is enclosed by a nanoscale void which prevents the reaction partners on the dehydrogenated side from diffusing away from each other. Moreover, the generally enhanced diffusivity in nanocrystalline systems may lower the kinetic barriers for the material's transformation and, thus, facilitate hydrogen absorption and desorption. PMID:19420657

  11. Modeling Mercury

    NASA Astrophysics Data System (ADS)

    Burger, M. H.; Killen, R. M.; M, N.; Sarantos, M.; Crider, D. H.; Vervak, R. J.

    2009-04-01

    Mercury has a tenuous exosphere created by the combined effects of solar radiation and micrometeoroid bombardment on the surface and the interaction of the solar wind with Mercury's magnetic field and surface. Observations of this exosphere provide essential data necessary for understanding the composition and evolution of Mercury's surface, as well as the interaction between Mercury's magnetosphere with the solar wind. The sodium component of the exosphere has been well observed from the ground (see review by Killen et al., 2007). These observations have revealed a highly variable and inhomogeneous exosphere with emission often peaking in the polar regions. Radiation acceleration drives exospheric escape producing a sodium tail pointing away from the sun which has been detected up to 1400 Mercury radii from the planet (Potter et al. 2002; Baumgardner et al. 2008). Calcium has also been observed in Mercury's exosphere showing a distribution distinct from sodium, although also variable (Killen et al. 2005). During the first two encounters with Mercury by MESSENGER, observations of the exosphere were made by the UltraViolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). Sodium and calcium emission were detected during both flybys, and magnesium was detected for the first time in Mercury's exosphere during the second flyby. The spatial distributions of these species showed significant, unexpected differences which suggest differences in the mechanisms responsible for releasing them from the surface. We present a Monte-Carlo model of sodium, magnesium, and calcium in Mercury's exosphere. The important source mechanisms for ejecting these species from the surface are sputtering by solar wind ions, photon-stimulated desorption, and micrometeoroid impact vaporization. Thermal desorption on the dayside does not supply enough energy to significantly populate the exosphere, although it does play a role in redistributing volatiles over the surface. In addition, atomic calcium can be produced from the dissociation of Ca-bearing molecules, such as CaO, which can be formed in impact vapors. The primary loss processes are the escape of neutrals ejected with sufficient energy and photoionization. The former process is supplemented by radiation pressure which accelerates neutrals anti-sunward such that escaping neutrals form a tail pointing away from the sun. Because Mercury's heliocentric distance and radial velocity vary during its orbit, both loss processes are functions of Mercury's true anomaly. We also consider the spatial distribution of the surface source. Impact vaporization is roughly isotropic over the surface, although there may be a leading/trailing asymmetry in the impact rate due to Mercury's orbital motion. Sputtering is confined to regions where the solar wind can impact the surface, which is shielded somewhat by the internal magnetic field. The surface regions vulnerable depend on the solar wind conditions. References: Baumgardner et al., GRL, 35, L03201, 2008. Killen, R.M. et al., Space Sci. Rev. 132, 433-509, 2007. Killen, R.M. et al., Icarus, 173, 300-311, 2005. Potter et al., Meteoritics & Planetary Sci., 37, 1165, 2002.

  12. Development of Hydride Absorber for Fast Reactor—Evaluation of Design Method for Hydride Absorber Rod—

    Microsoft Academic Search

    Yoshihisa Tahra; Tomohiko IWASKI; Kenji KONASKI

    2010-01-01

    A hydride control rod is being developed to improve the economy of fast reactor plants because it has a longer lifetime than the currently used B4C control rod. A hydride burnable poison rod is also under development to reduce the number of control rods by decreasing core excess reactivity. Hydrogen in the hydride control rod causes neutron spectrum interference between

  13. Hydrogen /Hydride/-air secondary battery

    NASA Technical Reports Server (NTRS)

    Sarradin, J.; Bronoel, G.; Percheron-Guegan, A.; Achard, J. C.

    1979-01-01

    The use of metal hydrides as negative electrodes in a hydrogen-air secondary battery seems promising. However, in an unpressurized cell, more stable hydrides that LaNi5H6 must be selected. Partial substitutions of nickel by aluminium or manganese increase the stability of hydrides. Combined with an air reversible electrode, a specific energy close to 100 Wh/kg can be expected.

  14. Vanadium hydride deuterium-tritium generator

    DOEpatents

    Christensen, L.D.

    1980-03-13

    A pressure controlled vanadium hydride gas generator was designed to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

  15. Complex hydrides for hydrogen storage

    DOEpatents

    Zidan, Ragaiy

    2006-08-22

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

  16. MERCURY IN TREE RINGS

    EPA Science Inventory

    Contamination caused by release of mercury into the environment is a growing concern. This release occurs due to a variety of anthropogenic activities and natural sources. After release, mercury undergoes complicated chemical transformations. The inorganic forms of mercury releas...

  17. Kinetics of hydride front in Zircaloy-2 and H release from a fractional hydrided surface

    SciTech Connect

    Diaz, M.; Gonzalez-Gonzalez, A.; Moya, J. S.; Remartinez, B.; Perez, S.; Sacedon, J. L. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Iberdrola, Tomas Redondo 3, 28033 Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain)

    2009-07-15

    The authors study the hydriding process on commercial nuclear fuel claddings from their inner surface using an ultrahigh vacuum method. The method allows determining the incubation and failure times of the fuel claddings, as well as the dissipated energy and the partial pressure of the desorbed H{sub 2} from the outer surface of fuel claddings during the hydriding process. The correlation between the hydriding dissipated energy and the amount of zirconium hydride (formed at different stages of the hydriding process) leads to a near t{sup 1/2} potential law corresponding to the time scaling of the reaction for the majority of the tested samples. The calibrated relation between energy and hydride thickness allows one to calculate the enthalpy of the {delta}-ZrH{sub 1.5} phase. The measured H{sub 2} desorption from the external surface is in agreement with a proposed kinetic desorption model from the hydrides precipitated at the surface.

  18. Mercury Unveiled

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    1997-01-01

    Mercury, the second smallest planet and the closest one to the Sun, may appear to some as a drab, colorless, heavily-cratered world. Not so. New analysis of data returned by the Mariner 10 mission in 1974 and 1975 reveals a surface with lava flows and deposits from explosive volcanic eruptions, variations in composition across its surface and into its crust, and a different chemical composition from the other inner planets. These discoveries were made by Mark Robinson at the United States Geological Survey in Flagstaff, Arizona (he is now at Northwestern University) and Paul Lucey of the University of Hawaii. Using improvements in computer and image-processing technologies, and a better understanding of how light reflects off planetary surfaces than was available in the mid-1970s, Robinson and Lucey manipulated the original data and produced a color image of Mercury that depicts compositional differences across its stark surface

  19. Sealed aerospace metal-hydride batteries

    Microsoft Academic Search

    Dwaine Coates

    1992-01-01

    Nickel metal hydride and silver metal hydride batteries are being developed for aerospace applications. There is a growing market for smaller, lower cost satellites which require higher energy density power sources than aerospace nickel-cadmium at a lower cost than space nickel-hydrogen. These include small LEO satellites, tactical military satellites and satellite constellation programs such as Iridium and Brilliant Pebbles. Small

  20. Integrated electrolyser—metal hydride compression system

    Microsoft Academic Search

    F. Laurencelle; Z. Dehouche; J. Goyette; T. K. Bose

    2006-01-01

    Metal hydride thermal compression is a reliable process to compress hydrogen without contamination. We report on the development of a three-stage metal hydride hydrogen compressor. It will compress a part of the hydrogen produced by an electrolyser and will recycle the heat released by the electrolytic cells as its principal energy supply. This compressor will raise the hydrogen pressure from

  1. Direct synthesis of catalyzed hydride compounds

    DOEpatents

    Gross, Karl J.; Majzoub, Eric

    2004-09-21

    A method is disclosed for directly preparing alkali metal aluminum hydrides such as NaAlH.sub.4 and Na.sub.3 AlH.sub.6 from either the alkali metal or its hydride, and aluminum. The hydride thus prepared is doped with a small portion of a transition metal catalyst compound, such as TiCl.sub.3, TiF.sub.3, or a mixture of these materials, in order to render them reversibly hydridable. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen while heating the mixture to about 125.degree. C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.

  2. Activated aluminum hydride hydrogen storage compositions and uses thereof

    DOEpatents

    Sandrock, Gary (Ringwood, NJ); Reilly, James (Bellport, NY); Graetz, Jason (Mastic, NY); Wegrzyn, James E. (Brookhaven, NY)

    2010-11-23

    In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

  3. MESSENGER: Exploring Mercury's Magnetosphere

    Microsoft Academic Search

    James A. Slavin; Stamatios M. Krimigis; Mario H. Acuña; Brian J. Anderson; Daniel N. Baker; Patrick L. Koehn; Haje Korth; Stefano Livi; Barry H. Mauk; Sean C. Solomon; Thomas H. Zurbuchen

    2007-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since the brief flybys of Mariner 10. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only ˜1000 to

  4. THE ROLE OF HYDRIDE SIZE, MATRIX STRENGTH.AND STRESS STATE ON FRACTURE INITIATION AT HYDRIDE PRECIPITATES IN ZIRCONIUM ALLOYS

    E-print Network

    Paris-Sud XI, Université de

    718 THE ROLE OF HYDRIDE SIZE, MATRIX STRENGTH.AND STRESS STATE ON FRACTURE INITIATION AT HYDRIDE to develop a theoretical understanding of KIH, a criterion for the initiation of fracture at hydride in the material tested (3). The conditions for fracture initiation at hydrides are, therefore, complex, requiring

  5. Mercury and health care

    PubMed Central

    Rustagi, Neeti; Singh, Ritesh

    2010-01-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries’ health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now. PMID:21120080

  6. Hydrogen-storing hydride complexes

    DOEpatents

    Srinivasan, Sesha S. (Tampa, FL); Niemann, Michael U. (Venice, FL); Goswami, D. Yogi (Tampa, FL); Stefanakos, Elias K. (Tampa, FL)

    2012-04-10

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  7. Regeneration of lithium aluminum hydride.

    PubMed

    Graetz, Jason; Wegrzyn, James; Reilly, James J

    2008-12-31

    Lithium aluminum hydride (LiAlH(4)) is a promising compound for hydrogen storage, with a high gravimetric and volumetric hydrogen density and a low decomposition temperature. Similar to other metastable hydrides, LiAlH(4) does not form by direct hydrogenation at reasonable hydrogen pressures; therefore, there is considerable interest in developing new routes to regenerate the material from the dehydrogenated products LiH and Al. Here we demonstrate a low-energy route to regenerate LiAlH(4) from LiH and Ti-catalyzed Al. The initial hydrogenation occurs in a tetrahydrofuran slurry and forms the adduct LiAlH(4).4THF. The thermodynamics of this reversible reaction were investigated by measuring pressure-composition isotherms, and the free energy was found to be small and slightly negative (DeltaG = -1.1 kJ/mol H(2)), suggesting an equilibrium hydrogen pressure of just under 1 bar at 300 K. We also demonstrate that the adduct LiAlH(4).4THF can be desolvated at low temperature to yield crystalline LiAlH(4). PMID:19053465

  8. Liquid suspensions of reversible metal hydrides

    DOEpatents

    Reilly, J.J.; Grohse, E.W.; Winsche, W.E.

    1983-12-08

    The reversibility of the process M + x/2 H/sub 2/ ..-->.. MH/sub x/, where M is a metal hydride former that forms a hydride MH/sub x/ in the presence of H/sub 2/, generally used to store and recall H/sub 2/, is found to proceed under a liquid, thereby to reduce contamination, provide better temperature control and provide in situ mobility of the reactants. Thus, a slurry of particles of a metal hydride former with an inert solvent is subjected to temperature and pressure controlled atmosphere containing H/sub 2/, to store hydrogen (at high pressures) and to release (at low pressures) previously stored hydrogen. The direction of the flow of the H/sub 2/ through the liquid is dependent upon the H/sub 2/ pressure in the gas phase at a given temperature. When the former is above the equilibrium absorption pressure of the respective hydride the reaction proceeds to the right, i.e., the metal hydride is formed and hydrogen is stored in the solid particle. When the H/sub 2/ pressure in the gas phase is below the equilibrium dissociation pressure of the respective hydride the reaction proceeds to the left, the metal hydride is decomposed and hydrogen is released into the gas phase.

  9. Sealed aerospace metal-hydride batteries

    NASA Astrophysics Data System (ADS)

    Coates, Dwaine

    1992-02-01

    Nickel metal hydride and silver metal hydride batteries are being developed for aerospace applications. There is a growing market for smaller, lower cost satellites which require higher energy density power sources than aerospace nickel-cadmium at a lower cost than space nickel-hydrogen. These include small LEO satellites, tactical military satellites and satellite constellation programs such as Iridium and Brilliant Pebbles. Small satellites typically do not have the spacecraft volume or the budget required for nickel-hydrogen batteries. NiCd's do not have adequate energy density as well as other problems such as overcharge capability and memory effort. Metal hydride batteries provide the ideal solution for these applications. Metal hydride batteries offer a number of advantages over other aerospace battery systems.

  10. Mercury Contamination of Aquatic Ecosystems

    NSDL National Science Digital Library

    D.P. Krabbenhoft

    This United States Geological Survey (USGS) factsheet contains information about US mercury contamination. Issues discussed include how mercury becomes a toxicological problem through bioaccumulation, human effects of mercury toxicity, and levels of atmospheric mercury. Mercury levels in fish are examined to determine how mercury gets into the environment and into the food chain.

  11. Metallic mercury recycling. Final report

    Microsoft Academic Search

    Beck

    1994-01-01

    Metallic mercury is known to be a hazardous material and is regulated as such. The disposal of mercury, usually by landfill, is expensive and does not remove mercury from the environment. Results from the Metallic Mercury Recycling Project have demonstrated that metallic mercury is a good candidate for reclamation and recycling. Most of the potential contamination of mercury resides in

  12. METALLIC HYDRIDES. Magnetic properties of laves-phase rare earth hydrides

    E-print Network

    Boyer, Edmond

    METALLIC HYDRIDES. Magnetic properties of laves-phase rare earth hydrides J. J. Rhyne and G. E on the rare earth site. The rare earth spins disorder at a temperature lower than the bulk Tc in ErFe2 H3 5 per formula unit assuming complete occupation of 3 tetrahedral sites. The heavy rare earth (RFe2

  13. EXPERIMENTAL INVESTIGATION OF STRAIN, DAMAGE AND FAILURE OF HYDRIDED ZIRCONIUM ALLOYS WITH VARIOUS HYDRIDE ORIENTATIONS

    Microsoft Academic Search

    A. Racine; M. Bornert; C. Cappelaere; D. Caldemaison

    This experimental investigation is devoted to the hydride embrittlement of fuel cladding tubes and especially to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4). The average hydrogen content of the material is about 200ppm, and

  14. Mercury: Where You Live

    MedlinePLUS

    ... for... Businesses Consumers Health Care Providers Parents Schools Mercury can be found most anywhere. On this page, you will find resources about mercury where you live - your home and community, your ...

  15. Optimal hydride fueled BWR assembly designs

    SciTech Connect

    Fratoni, M.; Greenspan, E. [Nuclear Engineering Dept., Univ. of California at Berkeley, Berkeley, CA 94720-1730 (United States)

    2006-07-01

    The feasibility of improving the performance of BWR's by using hydride fuel instead of oxide fuel is assessed. Performance improvements looked for including enhanced power density, simplified fuel bundle and core design and less negative void coefficient of reactivity. A 3-D neutronic analysis is performed to determine attainable discharge burn-up, pin-by-pin power distribution, axial power distribution, reactivity coefficients, reactivity worth of control elements and burnable absorber effects. It is found that hydride fuel bundle design can be greatly simplified by eliminating water rods and partial length fuel rods and by shrinking the water gaps surrounding the bundle box. As a result the hydride fuel bundle contains 96 full length fuel rods of a uniform composition versus 71 effective full length fuel rods of 8 different compositions of the reference oxide fuel bundle. The cruciform control elements are replaced by a cluster of control rods without increasing the number of control drive mechanisms. IFBA is identified as the preferred burnable poison. A companion study of the thermal-hydraulic and vibration characteristics of BWR cores predicts that the increase in the number of fuel rods per given core volume combined with the low peak-to-average pin-wise power distribution of hydride fuel designs enables increasing the BWR power density by up to 40% relative to the oxide fuel design. The net outcome is expected to be improved BWR economics even though hydride fuel requires higher uranium enrichment. Use of hydride fuel may also improve the stability of BWR's against power oscillations as the void coefficient of reactivity of hydride fuelled designs is less negative than that of oxide fuelled designs. (authors)

  16. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. (Department of Restorative Dentistry, School of Dentistry, Medical College of Georgia, Augusta (United States))

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  17. MERCURY SPECIATION AND CAPTURE

    EPA Science Inventory

    The speciation of mercury has a major impact on its removal in air pollution control equipment. The oxidized forms of mercury, mercuric chloride (HgCl2) in particular, is highly water-soluble and is easier to capture in wet FGD systems than elemental mercury (Hg0), which is not w...

  18. Mercury's sodium exosphere

    Microsoft Academic Search

    F. Leblanc; R. E. Johnson

    2003-01-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to

  19. Mercury recovering and recycling

    SciTech Connect

    Weyand, T.E.; Rose, M.V.

    1995-11-01

    Efficient, economical treatment of mercury-contaminated soils and industrial wastes requires a treatment process that reduces mercury content to near background levels and recovers the removed mercury in pure recyclable form without producing liquid, solid, or gaseous secondary wastes. Mercury Recovery Services, Inc. has successfully developed and placed commercial operation a medium-temperature thermal desorption process that has into co successfully achieved these goals. The efficacy of the MRS Process to treat mercury-contaminated soils and industrial wastes was first Demonstrated on a pilot scale by means of treating (a) simulated soils containing varying amounts of metallic mercury, mercury oxide, mercury sulfide and mercury chloride, (b) actual natural gas metering site pipeline clay, sandy, and loam soils having total mercury contents in the range of 250 ppm to 15,000 ppm, and (c) waste water treatment sludges from chloralkali production containing up to 20,000 ppm mercury and large significant concentrations of sulfur and chlorine. In every case, the residual total mercury content was reduced to less than 2 ppm after treatment. The performance of MRS` first mobile commercial thermal desorption unit compares very favorably with the previously reported pilot-scale results.

  20. Optimization of hydride fueled pressurized water reactor cores

    E-print Network

    Shuffler, Carter Alexander

    2004-01-01

    This thesis contributes to the Hydride Fuels Project, a collaborative effort between UC Berkeley and MIT aimed at investigating the potential benefits of hydride fuel use in light water reactors (LWRs). This pursuit involves ...

  1. Thin-film metal hydrides.

    PubMed

    Remhof, Arndt; Borgschulte, Andreas

    2008-12-01

    The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis. PMID:18980236

  2. High H? ionic conductivity in barium hydride.

    PubMed

    Verbraeken, Maarten C; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T S

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H(-)) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm(-1) at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on. PMID:25485988

  3. Reactivity of yttrium carboxylates toward alkylaluminum hydrides.

    PubMed

    Schädle, Christoph; Fischbach, Andreas; Herdtweck, Eberhardt; Törnroos, Karl W; Anwander, Reiner

    2013-11-25

    Yttrocene-carboxylate complex [Cp*2Y(OOCAr(Me))] (Cp*=C5Me5, Ar(Me) =C6H2Me3-2,4,6) was synthesized as a spectroscopically versatile model system for investigating the reactivity of alkylaluminum hydrides towards rare-earth-metal carboxylates. Equimolar reactions with bis-neosilylaluminum hydride and dimethylaluminum hydride gave adduct complexes of the general formula [Cp*2Y(?-OOCAr(Me))(?-H)AlR2] (R=CH2SiMe3, Me). The use of an excess of the respective aluminum hydride led to the formation of product mixtures, from which the yttrium-aluminum-hydride complex [{Cp*2Y(?-H)AlMe2(?-H)AlMe2(?-CH3)}2] could be isolated, which features a 12-membered-ring structure. The adduct complexes [Cp*2Y(?-OOCAr(Me))(?-H)AlR2] display identical (1)J(Y,H) coupling constants of 24.5 Hz for the bridging hydrido ligands and similar (89)Y NMR shifts of ?=-88.1 ppm (R=CH2SiMe3) and ?=-86.3 ppm (R=Me) in the (89)Y DEPT45 NMR experiments. PMID:24151216

  4. Thermal property measurements of high pressure metal hydrides

    Microsoft Academic Search

    Scott Michael Flueckiger

    2009-01-01

    Metal hydrides are potential materials for onboard hydrogen storage. Thermal property measurements are needed to optimize the thermal management design of metal hydride storage systems which require a measurement technique developed with considerations of the thermodynamics of the hydriding process and the pyrophoric nature of the material. In the present work, a transient plane source (TPS) apparatus was integrated with

  5. Accurate simplified dynamic model of a metal hydride tank

    Microsoft Academic Search

    Tim M. Brown; Jacob Brouwer; G. Scott Samuelsen; Franklin H. Holcomb; Joel King

    2008-01-01

    As proton exchange membrane fuel cell technology advances, the need for hydrogen storage intensifies. Metal hydride alloys offer one potential solution. However, for metal hydride tanks to become a viable hydrogen storage option, the dynamic performance of practical tank geometries and configurations must be understood and incorporated into fuel cell system analyses. A dynamic, axially-symmetric, multi-nodal metal hydride tank model

  6. Potassium Hydride in Paraffin: A Useful Base for Organic Synthesis

    E-print Network

    Taber, Douglass

    Potassium Hydride in Paraffin: A Useful Base for Organic Synthesis Douglass F. Taber taberdf@udel.edu ReceiVed July 7, 2006 The preparation of potassium hydride as a 1:1 homogenate be a generally useful base for organic synthesis. Sodium hydride (NaH), potassium tert-butoxide, and n-BuLi have

  7. Delayed hydride cracking of zirconium alloys

    SciTech Connect

    Yau, T.L. [Teledyne Wah Chang, Albany, OR (United States); Webster, R.T. [Webster (R.T.), Scio, OR (United States)

    1995-10-01

    High-strength zirconium alloys are susceptible to a mechanism for crack initiation and propagation termed delayed hydride cracking (DHC). In these alloys, it is possible to generate a large enough stress gradient so that hydrogen moves to the highly stressed areas. Therefore, hydrides precipitate and grow in these areas. When the tensile stress is sufficiently great, crack initiation starts at some of these hydrides. Crack propagation occurs by repeating the same process at the crack tip. Of concern for the chemical process industries is the DHC of Zr-2.5Nb welds. Results of long-term tests and case histories indicate that stress relieving is one of the major measures for preventing DHC, provided that ASME mechanical requirements are met.

  8. Decomposition of lithium magnesium aluminum hydride

    Microsoft Academic Search

    Hilde Grove; Ole Martin Løvvik; Weiming Huang; Susanne M. Opalka; Richard H. Heyn; Bjørn C. Hauback

    2011-01-01

    The quaternary aluminum hydride LiMg(AlH4)3 contains 9.7 wt% hydrogen, of which 7.2 wt% can be released in a two-step decomposition reaction via first formation of LiMgAlH6 and then the binary hydrides MgH2 and LiH. In-situ synchrotron radiation powder X–ray diffraction and thermal desorption spectroscopy measurements were performed to analyze the product distributions formed during the thermal decomposition of LiMg(AlD4)3. The first decomposition

  9. 1. VIEW OF A PORTION OF THE HYDRIDE PROCESSING LABORATORY. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW OF A PORTION OF THE HYDRIDE PROCESSING LABORATORY. OPERATIONS IN THE GLOVE BOX IN THE BACKGROUND OF THE PHOTOGRAPH INCLUDED HYDRIDING OF PLUTONIUM AND HYDRIDE SEPARATION. IN THE FOREGROUND, THE VACUUM MONITOR CONTROL PANEL MEASURED TEMPERATURES WITHIN THE GLOVEBOX. THE CENTER CONTROL PANEL REGULATED THE FURNACE INSIDE THE GLOVE BOX USED IN THE HYDRIDING PROCESSES. THIS EQUIPMENT WAS ESSENTIAL TO THE HYDRIDING PROCESS, AS WELL AS OTHER GLOVE BOX OPERATIONS. - Rocky Flats Plant, Plutonium Laboratory, North-central section of industrial area at 79 Drive, Golden, Jefferson County, CO

  10. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuña, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Livi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2007-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury offers our first opportunity to explore this planet’s miniature magnetosphere since the brief flybys of Mariner 10. Mercury’s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only ˜1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere, allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury’s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury’s interior. In addition, Mercury’s magnetosphere is the only one with its defining magnetic flux tubes rooted beneath the solid surface as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, ˜1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury’s magnetic tail. Because of Mercury’s proximity to the sun, 0.3-0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and recycling of neutrals and ions among the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury’s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection, and pick-up of planetary ions all playing roles in the generation of field-aligned electric currents. However, these field-aligned currents do not close in an ionosphere, but in some other manner. In addition to the insights into magnetospheric physics offered by study of the solar wind-Mercury system, quantitative specification of the “external” magnetic field generated by magnetospheric currents is necessary for accurate determination of the strength and multi-polar decomposition of Mercury’s intrinsic magnetic field. MESSENGER’s highly capable instrumentation and broad orbital coverage will greatly advance our understanding of both the origin of Mercury’s magnetic field and the acceleration of charged particles in small magnetospheres. In this article, we review what is known about Mercury’s magnetosphere and describe the MESSENGER science team’s strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic, magnetosphere.

  11. Process for low mercury coal

    DOEpatents

    Merriam, Norman W. (Laramie, WY); Grimes, R. William (Laramie, WY); Tweed, Robert E. (Laramie, WY)

    1995-01-01

    A process for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal.

  12. Process for low mercury coal

    DOEpatents

    Merriam, N.W.; Grimes, R.W.; Tweed, R.E.

    1995-04-04

    A process is described for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal. 4 figures.

  13. Hydridable material for the negative electrode in a nickel-metal hydride storage battery

    DOEpatents

    Knosp, Bernard (Neuilly-sur-Seine, FR); Bouet, Jacques (Paris, FR); Jordy, Christian (Dourdan, FR); Mimoun, Michel (Neuilly-sur-Marne, FR); Gicquel, Daniel (Lanorville, FR)

    1997-01-01

    A monophase hydridable material for the negative electrode of a nickel-metal hydride storage battery with a "Lave's phase" structure of hexagonal C14 type (MgZn.sub.2) has the general formula: Zr.sub.1-x Ti.sub.x Ni.sub.a Mn.sub.b Al.sub.c Co.sub.d V.sub.e where ##EQU1##

  14. Effects of ?-hydride precipitation at a crack tip on crack propagation in delayed hydride cracking of Zircaloy-2

    NASA Astrophysics Data System (ADS)

    Kubo, T.; Kobayashi, Y.

    2013-08-01

    Delayed hydride cracking (DHC) of Zircaloy-2 is one possible mechanism for the failure of boiling water reactor fuel rods in ramp tests at high burnup. Analyses were made for hydrogen diffusion around a crack tip to estimate the crack velocity of DHC in zirconium alloys, placing importance on effects of precipitation of ?-hydride. The stress distribution around the crack tip is significantly altered by precipitation of hydride, which was strictly analyzed using a finite element computer code. Then, stress-driven hydrogen diffusion under the altered stress distribution was analyzed by a differential method. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed in front of the crack tip, it grew almost steadily accompanying the interaction of hydrogen diffusion, hydride growth and the stress alteration by hydride precipitation. Finally, crack velocity was estimated from the calculated hydrogen flux into the crack tip as a function of temperature, stress intensity factor and material strength. There was qualitatively good agreement between calculation results and experimental data. The stress distribution around the crack tip is significantly altered by precipitation of hydride. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed in front of the crack tip, it grew almost steadily accompanying the interaction of hydrogen diffusion, hydride growth and the stress alteration by hydride precipitation. Crack velocity was estimated from the calculated hydrogen flux into the crack tip as a function of temperature, stress intensity factor and material strength. There was qualitatively good agreement between calculation results and experimental data. Macroscopic stress, ?c in a fiber reinforced composite with fibers aligned in a loading direction can be expressed as follows: ?c = ?fVf + ?m (1 - Vf), where suffices f, m and c refer to fiber, matrix and composite, respectively, and Vf is volume fraction of fibers.

  15. Ionic hydrogenations of hindered olefins at low temperature. Hydride transfer reactions of transition metal hydrides

    SciTech Connect

    Bullock, R.M.; Song, J.S. (Brookhaven National Lab., Upton, NY (United States))

    1994-09-21

    Sterically hindered olefins can be hydrogenated at -50[degree]C in dichloromethane using triflic acid (CF[sub 3]SO[sub 3]H) and a hydride donor. Mechanistic studies indicate that these reactions proceed by hydride transfer to the carbenium ion that is formed by protonation of the olefin. Olefins that form tertiary carbenium ions upon protonation are hydrogenated in high yields (90-100%). Styrenes generally produce lower yields of hydrogenated products (50-60%). Suitable hydride donors include HSiE[sub 3] and several transition metal carbonyl hydrides HW(CO)[sub 3]Cp, HW(CO)[sub 3]Cp[sup +], HMo-(CO)[sub 3]Cp, HMn(CO)[sub 5], HRe(CO)[sub 3], and HO[sub 3](CO)[sub 1]Cp*; Cp = [eta][sup 5]-C[sub 3]H[sub 5+], Cp* = [eta][sup 5]-C[sub 5]Me[sub 5]. A characteristic that is required for transition metal hydrides to be effective is that the cationic dihydrides (or dihydrogen complexes) that result from their protonation must have sufficient acidity to transfer a proton to the olefin, as well as sufficient thermal stability to avoid significant decomposition on the time scale of the hydrogenation reaction. Metal hydrides that fall due to insufficient stability of their protonated forms include HMo(CO)[sub 2](PPH[sub 3])Cp, HMo(CO)[sub 3]Cp*, and HFe(CO)[sub 2]Cp*. 62 refs., 2 tabs.

  16. Hydrides for Processing and Storing Tritium

    Microsoft Academic Search

    Theodore Motyka

    The Savannah River Site (SRS) has 50 years of experience in handling and processing tritium for defense and other special applications. During the past 20 years, a new technology, metal hy- dride technology, was introduced to the tritium facilities. This technology dramatically changed the way tritium and the other hydrogen isotopes were handled and processed at SRS. Metal hydrides allowed

  17. Hydride embrittlement in ZIRCALOY-4 plate: Part II. interaction between the tensile stress and the hydride morphology

    NASA Astrophysics Data System (ADS)

    Bai, J. B.; Ji, N.; Gilbon, D.; Prioul, C.; François, D.

    1994-06-01

    The effect of an applied tensile stress on the hydrides morphology in ZIRCALOY-4 was studied. To this end, the residual stresses around the hydride caused by the hydride precipitation was first evaluated. Considering the disability to predict hydride transformation stresses by ordinary macroscopical mechanical calculation in previous studies, X-ray diffraction (XRD) profile analysis and transmission electron microscopy (TEM) observations were carried out to quantify the microstructural evolution in hydrided ZIRCALOY-4. The residual microstrains and microstresses in the matrix and around the hydride were thus estimated. The big discrepancy between our results and the existing studies were explained by the major self-accomodation of phase transformation deformation remaining inside the hydrides and the local plastic accommodation of ZIRCALOY-4. In order to study the stress effect on hydride orientation and to estimate the hydride orientation threshold stresses, hydrogen was introduced into the specimens under tensile stress. A quantitative technique was used to evaluate the susceptibility to perpendicular hydride formation under the influence of texture, residual stresses, and externally applied tensile stresses, following an improved approach that had been first developed by Sauthoff and then applied to Zr-H system by Puls. Both analytical and experimental results indicate that the threshold stress for producing perpendicular hydrides varies with the microstructural features, the yield strength, and the residual stresses.

  18. Substorms on Mercury?

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Ness, N. F.; Yeates, C. M.

    1974-01-01

    Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there.

  19. Mercury, Venus, and Earth!

    NSDL National Science Digital Library

    bschiffer

    2009-10-21

    You will compare and contrast Mercury, Venus, and Earth. While looking at these different websites, use the information to fill in your handout of a column chart and on the back answer the questions you are asked on here. First view this website and record on your chart the distance from the sun Mercury,Venus, and Earth are. Now, learn about Mercury! What is the surface ...

  20. Dynamic duo captures mercury

    SciTech Connect

    Senior, C.; Adams, B. [Reaction Engineering International (United States)

    2006-02-15

    There is strong evidence that the combination of wet flue gas desulphurisation (FGD) scrubbers and selective catalytic reduction (SCR) can prove a viable and formidable combination for knocking out mercury. This article analyzes the capabilities and limitations of the SCR-FGD combination for mercury compliance, including applicability to different types of coal and issues with scrubber by-products. 3 figs.

  1. Getting rid of mercury

    SciTech Connect

    Reisch, M.S.

    2008-11-24

    Anticipating a US rule on mercury removal from coal flue gas, technology providers jockey for position. By 2013, if the federal rule imposing regulation of mercury emissions which have begun or are about to begin in 20 eastern states goes nationwide, mercury control will be big business. For the near term, utilities are adopting activated carbon to control mercury emissions. McIlvaine Co. projects the US market for activated carbon will jump from 10 million lb in 2010 to 350 million by 2013. Norit and Calgon Carbon are already increasing production of activated carbon (mainly from coal) and ADA Environmental Solutions (ADA-ES) is building a new plant. Albermarle is developing a process to treat activated carbon with bromine; Corning has developed a sulfur impregnated activated carbon filtration brick. New catalysts are being developed to improve the oxidation of mercury for removal from flue gas. 2 photos.

  2. Mercury's Seasonal Sodium Exosphere

    NASA Astrophysics Data System (ADS)

    Cassidy, T. A.; Merkel, A. W.; McClintock, W. E.; Burger, M. H.; Killen, R. M.; Sarantos, M.; Sprague, A. L.; Vervack, R. J.; Solomon, S. C.

    2012-09-01

    Mercury's tenuous Na exosphere was discovered in 1985, and has since been observed by a variety of Earth-based telescopes (see summary in [1]). The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) UVVS (UltraViolet and Visible Spectrometer) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbiting Mercury provides the first up-close look at the Na exosphere [2]. We describe and interpret data from a subset of UVVS observations: dayside limb scans. These observations are altitude profiles of Na emission within above Mercury's dayside equatorial surface. This analysis focuses on the near-surface portion of the limb scans (within 1500km), where we were able to fit the data with a simple model.

  3. Getting Mercury out of Schools.

    ERIC Educational Resources Information Center

    1999

    This guide was prepared while working with many Massachusetts schools to remove items that contain mercury and to find suitable alternatives. It contains fact sheets on: mercury in science laboratories and classrooms, mercury in school buildings and maintenance areas, mercury in the medical office and in medical technology classrooms in vocational…

  4. MERCURY MULTI-YEAR PLAN

    EPA Science Inventory

    A 1997 EPA Mercury Study Report to Congress discussed the magnitude of mercury emissions in the United States, and concluded that a plausible link exists between human activities that release mercury from industrial and combustion sources in the United States and methyl mercury c...

  5. A theoretical and experimental study of hydrides in zirconium alloys

    Microsoft Academic Search

    A. A. Shmakov; D. Yan; R. L. Eadie

    2006-01-01

    A method developed for computing the critical length and thickness of hydride plates formed in delayed hydride cracking (DHC)\\u000a in zirconium alloys is considered. The model is based on analyzing the distribution of tensile stresses in the plane of a\\u000a sharp normal tensile crack. The characteristics of hydrides formed due to DHC in reactor tubes produced from alloy Zr-2.5%\\u000a Nb

  6. HYDRIDE-INDUCED EMBRITTLEMENT IN METALS - STRESS AND TEMPERATURE EFFECTS

    Microsoft Academic Search

    A. G. Varias; A. R. Massih

    A robust mathematical model for the hydrogen embrittlement of hydride forming metals has been developed. The model takes into account the coupling of the operating physical processes, namely: (i) hydrogen diffusion, (ii) hydride precipitation, (iii) non-mechanical energy flow, and (iv) hydride\\/solid-solution deformation. Crack growth is simulated by using a new version of de-cohesion model with time-dependent energy of de-cohesion due

  7. Growth and decomposition of lithium and lithium hydride on nickel

    Microsoft Academic Search

    Jakob Engbæk; Gunver Nielsen; Jane H. Nielsen; Ib Chorkendorff

    2006-01-01

    In this paper we have investigated the deposition, structure and decomposition of lithium and lithium-hydride films on a nickel substrate. Using surface sensitive techniques it was possible to quantify the deposited Li amount, and to optimize the deposition procedure for synthesizing lithium-hydride films.By only making thin films of LiH it is possible to study the stability of these hydride layers

  8. Synthesis and properties of platinum hydride

    NASA Astrophysics Data System (ADS)

    Scheler, Thomas; Degtyareva, Olga; Marqués, Miriam; Guillaume, Christophe L.; Proctor, John E.; Evans, Shaun; Gregoryanz, Eugene

    2011-06-01

    Synchrotron x-ray diffraction experiments on compressed platinum-hydrogen mixtures reveal the formation of platinum hydride at a pressure of 27(1) GPa at room temperature. This compound exhibits two phases, PtH-I and PtH-II, coexisting up to the pressure of 42 GPa, above which the single phase of PtH-II is observed. Pt atoms in the PtH-II phase are shown to form a hexagonal closed-packed structure. This phase exhibits a high bulk modulus of 310 (10) GPa and is stable up to at least 53 GPa. Ab initio calculations show that PtH-II is superconducting with Tc = 12 K at 90 GPa, the highest temperature of superconducting transition among any known metal hydride.

  9. Unoccupied electronic states in cerium hydrides

    NASA Astrophysics Data System (ADS)

    Osterwalder, J.; Schlapbach, L.

    1985-05-01

    We present UV isochromat spectra of polycrystalline CeH 2.1 and CeH 2.9. The intensity at EF is small in CeH 2.1 and vanishes in CeH 2.9 as it is expected from XPS, UPS and conductivity data. In both hydrides broad features (?2 eV FWHM) appear between 4 and 5 eV above EF. This is in qualitative agreement with bandstructure calculations.

  10. Lightweight hydrides for automotive storage of hydrogen

    SciTech Connect

    Rohy, D.A.; Nachman, J.F.; Argabright, T.A.

    1981-01-01

    Hydrogen is a potential automotive fuel in mid- and far-term projections. The use of hydrogen as an energy carrier is dependent on the solution of two primary technical problems: inexpensive production of hydrogen and lightweight storage of hydrogen. This paper addresses the storage problem. Development of the magnesium hydride alloys is described and related to the requirements of the automotive SI (spark ignition) engine. 3 refs.

  11. The Thermal Decomposition of Lithium Aluminium Hydride

    Microsoft Academic Search

    W. E. Garner; E. W. Haycock

    1952-01-01

    Lithium aluminium hydride on heating decomposes in three stages: (a) an initial surface reaction during the induction period, followed by (b) an interface reaction giving an S-shaped pressure against time curve, corresponding to LiAlH4rightharpoonup LiAlH2 + H2, and (c) a slow process during which a third hydrogen atom is liberated. The initial reaction is rapid at first and then slows

  12. The IEA/DOE/SNL on-line hydride databases

    NASA Astrophysics Data System (ADS)

    Sandrock, G.; Thomas, G.

    2001-04-01

    A series of comprehensive hydride databases have been constructed and made freely available on the Internet (URL http://hydpark.ca.sandia.gov). They include extensive listings of alloys reported to hydride, detailed engineering properties on selected hydrogen-storage elements and alloys and a hydride-applications database. These databases and an associated reference database are described, along with other hydride information available on the web site. The databases were created under the auspices of the International Energy Agency (IEA) with financial support from the U.S. Department of Energy (DOE) and Internet service support from the Sandia National Laboratories (SNL).

  13. Investigation of yttrium and yttrium hydride by AES and REELS

    NASA Astrophysics Data System (ADS)

    Bracconi, P.; Pörschke, E.; Lässer, R.

    1988-08-01

    The results of combined investigations by Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS) of thin films of yttrium and yttrium hydride are presented. The hydride phase was prepared by exposing evaporated metal films to hydrogen in a high pressure reaction chamber connected to the main UHV vessel. Special attention was paid to the effects of surface contamination by oxygen. The specific spectroscopic characteristics of the metal and the hydride phase are compared and analysed in terms of the known electronic structures of yttrium and yttrium hydrides.

  14. AC impedance studies on metal hydride electrodes

    SciTech Connect

    Zhang, W.; Sridhar Kumar, M.P.; Srinivasan, S.; Ploehn, H.J. [Texas A and M Univ., College Station, TX (United States)

    1995-09-01

    The metal hydride (MH{sub x}) electrode is the negative electrode in one of the most advanced secondary batteries (i.e., nickel/metal hydride). The objective of this study is to obtain insight on the mechanism of the hydriding/dehydriding reaction in the battery by using the electrochemical impedance spectroscopy (EIS) technique. An equivalent circuit for the MH{sub x} electrode reaction is proposed. The rate capability of charge and discharge of the MH{sub x} electrode is determined by the kinetics of the charge-transfer reaction at the allow surface, which is mainly represented by the EIS responses in the low frequency region. Transient and pseudo-steady-state analyses (cyclic voltammetry and potential vs. current density behavior) qualitatively and quantitatively support the EIS results. EIS studies on electrodes with (1) three types of binding additives, (2) varying amounts of active materials, and (3) two types of alloys as active materials demonstrate the usefulness of this technique for developing electrodes with the optimum composition and structure.

  15. Plasmonic hydrogen sensing with nanostructured metal hydrides.

    PubMed

    Wadell, Carl; Syrenova, Svetlana; Langhammer, Christoph

    2014-12-23

    In this review, we discuss the evolution of localized surface plasmon resonance and surface plasmon resonance hydrogen sensors based on nanostructured metal hydrides, which has accelerated significantly during the past 5 years. We put particular focus on how, conceptually, plasmonic resonances can be used to study metal-hydrogen interactions at the nanoscale, both at the ensemble and at the single-nanoparticle level. Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodynamics, and acceptable long-term stability. Therefore, a brief introduction to the thermodynamics of metal hydride formation is also given. However, plasmonic hydrogen sensors not only are of academic interest as research tool in materials science but also are predicted to find more practical use as all-optical gas detectors in industrial and medical applications, as well as in a future hydrogen economy, where hydrogen is used as a carbon free energy carrier. Therefore, the wide range of different plasmonic hydrogen sensor designs already available is reviewed together with theoretical efforts to understand their fundamentals and optimize their performance in terms of sensitivity. In this context, we also highlight important challenges to be addressed in the future to take plasmonic hydrogen sensors from the laboratory to real applications in devices, including poisoning/deactivation of the active materials, sensor lifetime, and cross-sensitivity toward other gas species. PMID:25427244

  16. Mercury in the ecosystem

    SciTech Connect

    Mitra, S.

    1986-01-01

    This treatise on the environmental dispersion of mercury emphasizes the importance of ''mercury-consciousness'' in the present-day world, where rapidly expanding metallurgical, chemical, and other industrial developments are causing widespread contamination of the atmosphere, soil, and water by this metal and its toxic organic derivatives. Concepts concerning the mechanism of mercury dispersion and methyl-mercury formation in the physico-biological ecosystem are discussed in detail and a substantial body of data on the degree and nature of the mercury contamination of various plants, fish, and land animals by industrial and urban effluents is presented. Various analytical methods for the estimation of mercury in inorganic and organic samples are presented. These serve as a ready guide to the selection of the correct method for analyzing environmental samples. This book is reference work in mercury-related studies. It is written to influence industrial policies of governments in their formulation of control measures to avoid the recurrence of human tragedies such as the well-known Minamata case in Japan, and the lesser known cases in Iraq, Pakistan, and Guatamala.

  17. Metallic mercury recycling. Final report

    SciTech Connect

    Beck, M.A.

    1994-07-01

    Metallic mercury is known to be a hazardous material and is regulated as such. The disposal of mercury, usually by landfill, is expensive and does not remove mercury from the environment. Results from the Metallic Mercury Recycling Project have demonstrated that metallic mercury is a good candidate for reclamation and recycling. Most of the potential contamination of mercury resides in the scum floating on the surface of the mercury. Pinhole filtration was demonstrated to be an inexpensive and easy way of removing residues from mercury. The analysis method is shown to be sufficient for present release practices, and should be sufficient for future release requirements. Data from tests are presented. The consistently higher level of activity of the filter residue versus the bulk mercury is discussed. Recommendations for the recycling procedure are made.

  18. Mercury exposure and children's health.

    PubMed

    Bose-O'Reilly, Stephan; McCarty, Kathleen M; Steckling, Nadine; Lettmeier, Beate

    2010-09-01

    Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health. PMID:20816346

  19. The Study of Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, Louise M.; Bedini, Peter D.

    2010-01-01

    When the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft enters orbit about Mercury in March 2011 it will begin a new phase in an age-old scientific study of the innermost planet. Despite being visible to the unaided eye, Mercury's proximity to the Sun makes it extremely difficult to observe from Earth. Nonetheless, over the centuries man has pursued a quest to understand the elusive planet, and has teased out information about its motions in the sky, its relation to the other planets, and its physical characteristics. A great leap was made in our understanding of Mercury when the Mariner 10 spacecraft flew past it three times in the mid-1970s, providing a rich set of close-up observations. Now, three decades later, The MESSENGER spacecraft has also visited the planet three times, and is poised to add significantly to the study with a year-long orbital observation campaign.

  20. Mercury Releases and Spills

    MedlinePLUS

    ... non-mercury substance. NOTE: If there is a paper calibration strip inside of the thermometer that includes ... thick) 3. rubber, nitrile or latex gloves 4. paper towels 5. cardboard or squeegee 6. eyedropper 7. ...

  1. Mercury iodide crystal growth

    NASA Technical Reports Server (NTRS)

    Cadoret, R.

    1982-01-01

    The purpose of the Mercury Iodide Crystal Growth (MICG) experiment is the growth of near-perfect single crystals of mercury Iodide (HgI2) in a microgravity environment which will decrease the convection effects on crystal growth. Evaporation and condensation are the only transformations involved in this experiment. To accomplish these objectives, a two-zone furnace will be used in which two sensors collect the temperature data (one in each zone).

  2. Mercury CEM Calibration

    SciTech Connect

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  3. Performance and cost analysis of a hydride air conditioning system

    Microsoft Academic Search

    1977-01-01

    Results are presented of a performance and cost analysis of a metal hydride air conditioning (heat pump) system as compared to conventional absorption heat pumps. The system analyzed represents one of several possible implementations of the Hydride Conversion and Storage System (HYCSOS) concept developed by the Argonne National Laboratory. Due to the preliminary state of development of the HYCSOS concept,

  4. Method of making crack-free zirconium hydride

    DOEpatents

    Sullivan, Richard W. (Denver, CO)

    1980-01-01

    Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

  5. A nickel metal hydride battery for electric vehicles

    Microsoft Academic Search

    S. R. Ovshinsky; M. A. Fetcenko; J. Ross

    1993-01-01

    Widespread use of electric vehicles can have significant impact on urban air quality, national energy independence, and international balance of trade. An efficient battery is the key technological element to the development of practical electric vehicles. The science and technology of a nickel metal hydride battery, which stores hydrogen in the solid hydride phase and has high energy density, high

  6. Solubility of hydrogen isotopes in stressed hydride-forming metals

    Microsoft Academic Search

    C. E. Coleman; J. F. R. Ambler

    1983-01-01

    Components made from hydride-forming metals can be brittle when particles of hydride are present. The solid solubility limit of hydrogen in these metals needs to be known so that fracture resistance can be properly assessed. Stress affects the solubility of hydrogen in metals. As hydrogen dissolves the metal volume increases, an applied hydrostatic tensile stress supplies work to increase the

  7. Ab initio treatment of electron correlations in polymers: Lithium hydride chain and beryllium hydride polymer

    E-print Network

    Birkenheuer, Uwe

    H and beryllium hydride Be2H4 . First, employing a Wannier-function-based approach, the systems are studied Hartree­Fock Wannier functions of the infinite chain into the complementary space of localized unoccupied for the treatment of large molecules.3 Simi- larly, in infinite systems localized Wannier functions provide a better

  8. Binuclear cyclopentadienylrhenium hydride chemistry: terminal versus bridging hydride and cyclopentadienyl ligands.

    PubMed

    Gao, Xiaozhen; Li, Nan; King, R Bruce; Schaefer, Henry F

    2015-01-01

    Theoretical studies predict the lowest energy structures of the binuclear cyclopentadienylrhenium hydrides Cp2Re2H n (Cp = ?(5)-C5H5; n?=?4, 6, 8) to have a central doubly bridged Re2(?-H)2 unit with terminal ?(5)-Cp rings and the remaining hydrides as terminal ligands. However, the lowest energy Cp2Re2H2 structure by more than 12 kcal mol(-1) has one terminal ?(5)-Cp ring, a bridging ?(3),?(2)-Cp ring, and two terminal hydride ligands bonded to the same Re atom. The lowest energy hydride-free Cp2Re2 structure is a perpendicular structure with two bridging ?(3),?(2)-Cp rings. The previously predicted bent singlet Cp2Re2 structure with terminal ?(5)-Cp rings and a formal Re-Re sextuple bond lies ?37 kcal mol(-1) above this lowest energy (?(3),?(2)-Cp)2Re2 structure. The thermochemistry of the CpReH n and Cp2Re2H n systems is consistent with the reported synthesis of the permethylated derivatives Cp*ReH6 and Cp*2Re2H6 (Cp* = ?(5)-Me5C5) as very stable compounds. Additionally, natural bond orbital analysis, atoms-in-molecules and overlap population density-of-state in AOMIX were applied to present the existence of rhenium-rhenium multiple bonds. PMID:25605597

  9. Mercury Research in the USGS

    NSDL National Science Digital Library

    Announcements, publications, and science activities by the US Geological Survey (USGS) regarding the widespread contaminant mercury are available at this metasite from the USGS. The site brings together links to METAALICUS, a US-Canada joint mercury assessment project, the USGS page on mercury contamination of aquatic ecosystems, nationwide fish advisories, and the EPA's Mercury Report to Congress. Tables giving locations, status and contact information for USGS mercury projects can be read in .pdf or .xls format. USGS's mercury research is part of their Mineral Resources Division.

  10. Mercury exposure and public health.

    PubMed

    Clifton, Jack C

    2007-04-01

    Mercury is a metal that is a liquid at room temperature. Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced. In high enough doses, all forms of mercury can produce toxicity. The most devastating tragedies related to mercury toxicity in recent history include Minamata Bay and Niagata, Japan in the 1950s, and Iraq in the 1970s. More recent mercury toxicity issues include the extreme toxicity of the dimethylmercury compound noted in 1998, the possible toxicity related to dental amalgams, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal. PMID:17448359

  11. Porous metal hydride composite and preparation and uses thereof

    DOEpatents

    Steyert, William A. (Los Alamos, NM); Olsen, Clayton E. (Los Alamos, NM)

    1982-01-01

    A composite formed from large pieces of aggregate formed from (1) metal hydride (or hydride-former) powder and (2) either metal powder or plastic powder or both is prepared. The composite has large macroscopic interconnected pores (much larger than the sizes of the powders which are used) and will have a very fast heat transfer rate and low windage loss. It will be useful, for example, in heat engines, hydrogen storage devices, and refrigerator components which depend for their utility upon both a fast rate of hydriding and dehydriding. Additionally, a method of preparing the composite and a method of increasing the rates of hydriding and dehydriding of metal hydrides are also given.

  12. Porous metal hydride composite and preparation and uses thereof

    DOEpatents

    Steyert, W.A.; Olsen, C.E.

    1980-03-12

    A composite formed from large pieces of aggregate formed from (1) metal hydride (or hydride-former) powder and (2) either metal powder or plastic powder or both is prepared. The composite has large macroscopic interconnected pores (much larger than the sizes of the powders which are used) and will have a very fast heat transfer rate and low windage loss. It will be useful, for example, in heat engines, hydrogen storage devices, and refrigerator components which depend for their utility upon both a fast rate of hydriding and dehydriding. Additionally, a method of preparing the composite and a method of increasing the rates of hydriding and dehydriding of metal hydrides are also given.

  13. Recent advances in metal hydrides for clean energy applications

    SciTech Connect

    Ronnebro, Ewa; Majzoub, Eric H.

    2013-06-01

    Metal hydrides are a fascinating class of materials that can be utilized for a surprising variety of clean energy applications, including smart solar collectors, smart windows, sensors, thermal energy storage, and batteries, in addition to their traditional application for hydrogen storage. Over the past decade, research on metal hydrides for hydrogen storage increased due to global governmental incentives and an increased focus on hydrogen storage research for polymer electrolyte membrane fuel cell operation. Tremendous progress has been made in so-called complex metal hydrides for hydrogen storage applications with the discovery of many new hydrides containing covalently bound complex anions. Many of these materials have applications beyond hydrogen storage and are being investigated for lithium-ion battery separator and anode materials. In this issue of MRS Bulletin , we present the state of the art of key evolving metal-hydride-based clean energy technologies with an outlook toward future needs.

  14. Growth and decomposition of lithium and lithium hydride on nickel

    NASA Astrophysics Data System (ADS)

    Engbæk, Jakob; Nielsen, Gunver; Nielsen, Jane H.; Chorkendorff, Ib

    2006-04-01

    In this paper we have investigated the deposition, structure and decomposition of lithium and lithium-hydride films on a nickel substrate. Using surface sensitive techniques it was possible to quantify the deposited Li amount, and to optimize the deposition procedure for synthesizing lithium-hydride films. By only making thin films of LiH it is possible to study the stability of these hydride layers and compare it directly with the stability of pure Li without having any transport phenomena or adsorbed oxygen to obscure the results. The desorption of metallic lithium takes place at a lower temperature than the decomposition of the lithium-hydride, confirming the high stability and sintering problems of lithium-hydride making the storage potential a challenge.

  15. Mercury and Mink. II. Experimental methyl mercury intoxication.

    PubMed Central

    Wobeser, G; Nielsen, N O; Schiefer, B

    1976-01-01

    Adult female mink were fed rations containing 1.1, 1.8, 4.8, 8.3 and 15.0 ppm mercury as methyl mercury chloride over a 93 day period. Histopathological evidence of injury was present in all groups. Mink fed rations containing 1.8 to 15.0 ppm mercury developed clinical intoxication within the experimental period. The rapidity of onset of clinical intoxication was directly related to the mercury content of the ration. Mercury concentration in tissue of mink which died were similar, despite differences in mercury content of the diets and time of death. The average mercury concentration in the brain of mink which died was 11.9 ppm. The lesions of methyl mercury poisoning are described and criteria for diagnosis are discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:1000376

  16. GEOCHEMICAL FACTORS GOVERNING METHYL MERCURY PRODUCTION IN MERCURY CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Bench scale experiments were conducted to improve our understanding of aquatic mercury transformation processes (biotic and abiotic), specifically those factors which govern the production of methyl mercury (MeHg) in sedimentary environments. The greatest cause for concern regar...

  17. Modular hydride beds for mobile applications

    SciTech Connect

    Malinowski, M.E.; Stewart, K.D.

    1997-08-01

    Design, construction, initial testing and simple thermal modeling of modular, metal hydride beds have been completed. Originally designed for supplying hydrogen to a fuel cell on a mobile vehicle, the complete bed design consists of 8 modules and is intended for use on the Palm Desert Vehicle (PDV) under development at the Schatz Energy Center, Humbolt State University. Each module contains approximately 2 kg of a commercially available, low temperature, hydride-forming metal alloy. Waste heat from the fuel cell in the form of heated water is used to desorb hydrogen from the alloy for supplying feed hydrogen to the fuel cell. In order to help determine the performance of such a modular bed system, six modules were constructed and tested. The design and construction of the modules is described in detail. Initial testing of the modules both individually and as a group showed that each module can store {approximately} 30 g of hydrogen (at 165 PSIA fill pressure, 17 C), could be filled with hydrogen in 6 minutes at a nominal, 75 standard liters/min (slm) fueling rate, and could supply hydrogen during desorption at rates of 25 slm, the maximum anticipated hydrogen fuel cell input requirement. Tests made of 5 modules as a group indicated that the behavior of the group run in parallel both in fueling and gas delivery could be directly predicted from the corresponding, single module characteristics by using an appropriate scaling factor. Simple thermal modeling of a module as an array of cylindrical, hydride-filled tubes was performed. The predictions of the model are in good agreement with experimental data.

  18. Development of a Potential Surface for Simulation of Proton and Hydride Transfer Reactions in Solution: Application to NADH Hydride Transfer

    E-print Network

    Hammes-Schiffer, Sharon

    Development of a Potential Surface for Simulation of Proton and Hydride Transfer Reactions surface that describes these reactions must incorporate quantum mechanical effects such as the formation that incorporates significant quantum mechanical effects for proton and hydride transfer reactions in solution

  19. Metal hydride fuel storage and method thereof

    DOEpatents

    Morse, Jeffrey D. (Martinez, CA); Jankowski, Alan F. (Livermore, CA); Yu, Conrad (Antioch, CA)

    2010-08-10

    An apparatus having a first substrate having (1) a cavity, (2) one or more resistive heaters, and (3) one or more coatings forming a diffusion barrier to hydrogen; a second substrate having (1) an outlet valve comprising a pressure relief structure and (2) one or more coatings forming a diffusion barrier to hydrogen, wherein said second substrate is coupled to said first substrate forming a sealed volume in said cavity; a metal hydride material contained within said cavity; and a gas distribution system formed by coupling a microfluidic interconnect to said pressure relief structure. Additional apparatuses and methods are also disclosed.

  20. IMC hydrides with high hydrogen dissociation pressure

    Microsoft Academic Search

    T. A. Zotov; R. B. Sivov; E. A. Movlaev; S. V. Mitrokhin; V. N. Verbetsky

    2011-01-01

    Hydrogen sorption properties of a large variety of solid solutions on the base of ZrCr2 and TiFe2 intermetallic compounds are studied at pressures up to 300MPa. Partial substitution of Cr by small amounts of Me=Al, Mn, Mo, Ni and B does not significantly change the H\\/M ratio of hydrides of the Ti(Cr1?xMex)2?a alloys with 0

  1. Stress-reorientation of hydrides and hydride embrittlement of Zr-2.5 wt% Nb pressure tube alloy

    NASA Astrophysics Data System (ADS)

    Singh, R. N.; Kishore, R.; Singh, S. S.; Sinha, T. K.; Kashyap, B. P.

    2004-02-01

    Hydrogen in excess of the terminal solid solubility precipitates out as a brittle hydride phase in zirconium alloys. The hydrides acquire platelet shaped morphology due to their accommodation in the matrix and can cause severe embrittlement, especially when these are oriented normal to the tensile stress axis. The precipitation of hydride platelets normal to the tensile stress when cooled under stress from a solution-annealing temperature is commonly referred to as 'stress-reorientation'. The stress-reorientation is associated with a threshold stress below which no reorientation is observed. In this work, stress-reorientation of hydrides was investigated for unirradiated, cold worked and stress-relieved Zr-2.5 wt% Nb pressure tube material for a reorientation temperature of 423-723 K. The effect of the reoriented hydrides on the tensile properties of the Zr-2.5 wt% Nb pressure tube alloy was evaluated in the temperature range of 298-573 K.

  2. Windows to the Universe: Mercury

    NSDL National Science Digital Library

    This site, created by a partnership between the University of Michigan and the University Corporation for Atmospheric Research (UCAR) offers information on the planet Mercury. Some topics include: the atmosphere, surface, and interior of Mercury, missions to Mercury, recent discoveries, and myths and culture related to Mercury. There are also numerous pictures and additional websites to find more information. A Spanish translation to this useful website is also available.

  3. Metal hydrides for lithium-ion batteries.

    PubMed

    Oumellal, Y; Rougier, A; Nazri, G A; Tarascon, J-M; Aymard, L

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH(2) with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH(2) electrode shows a large, reversible capacity of 1,480 mAh g(-1) at an average voltage of 0.5 V versus Li(+)/Li(o) which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH(2). Furthermore, the reaction is not specific to MgH(2), as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH(2), which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries. PMID:18849978

  4. Metal hydrides for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Oumellal, Y.; Rougier, A.; Nazri, G. A.; Tarascon, J.-M.; Aymard, L.

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH2 with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH2 electrode shows a large, reversible capacity of 1,480mAhg-1 at an average voltage of 0.5V versus Li+/Li? which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH2. Furthermore, the reaction is not specific to MgH2, as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH2, which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries.

  5. Sensing Mercury for Biomedical and Environmental Monitoring

    PubMed Central

    Selid, Paul D.; Xu, Hanying; Collins, E. Michael; Face-Collins, Marla Striped; Zhao, Julia Xiaojun

    2009-01-01

    Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution and reduce mercury damage to human health, sensitive determination of mercury is important. This article summarizes some current sensors for the determination of both abiotic and biotic mercury. A wide array of sensors for monitoring mercury is described, including biosensors and chemical sensors, while piezoelectric and microcantilever sensors are also described. Additionally, newly developed nanomaterials offer great potential for fabricating novel mercury sensors. Some of the functional fluorescent nanosensors for the determination of mercury are covered. Afterwards, the in vivo determination of mercury and the characterization of different forms of mercury are discussed. Finally, the future direction for mercury detection is outlined, suggesting that nanomaterials may provide revolutionary tools in biomedical and environmental monitoring of mercury. PMID:22346707

  6. INVESTIGATIONS WITH MERCURY FLOW REACTOR

    EPA Science Inventory

    The objective of the research performed in the Mercury Flow Reactor is to investigate short residence-time (seconds) adsorption of mercury species using different sorbents. Emphasis is placed on the effects of mercury concentration, flow rates, reaction temperatures, exposure ti...

  7. Molecular rare-earth-metal hydrides in non-cyclopentadienyl environments.

    PubMed

    Fegler, Waldemar; Venugopal, Ajay; Kramer, Mathias; Okuda, Jun

    2015-02-01

    Molecular hydrides of the rare-earth metals play an important role as homogeneous catalysts and as counterparts of solid-state interstitial hydrides. Structurally well-characterized non-metallocene-type hydride complexes allow the study of elementary reactions that occur at rare-earth-metal centers and of catalytic reactions involving bonds between rare-earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available. PMID:25413985

  8. Carbon-Fluorine Bond Cleavage by Zirconium Metal Hydride Complexes

    E-print Network

    Jones, William D.

    Carbon-Fluorine Bond Cleavage by Zirconium Metal Hydride Complexes Brian L. Edelbach, A. K. Fazlur, Rochester, New York 14627 Received April 8, 1999 The zirconium hydride dimer [Cp2ZrH2]2 reacts with C6F6. [Cp2ZrH2]2 reacts with C6F5H to give Cp2Zr(p-C6F4H)F, Cp2ZrF2, C6F4H2, and H2. The zirconium hydride

  9. Follow that mercury!

    SciTech Connect

    Linero, A.A. [Florida Department of Environmental Protection, Tallahassee, FL (United States)

    2008-07-01

    The article discusses one technology option for avoiding release of mercury captured by power plant pollution control equipment in order to render it usable in concrete. This is the use of selective catalytic reduction for NOx control and lime spray dryer absorbers (SDA) for SO{sub 2} control prior to particulate collection by fabric filters. In this scenario all mercury removed is trapped in the fabric filter baghouse. The US EPA did not establish mercury emission limits for existing cement plants in the latest regulation 40 CFR 63, Subpart LLL (December 2006) and was sued by the Portland Cement Association because of the Hg limits established for new kilns and by several states and environmental groups for the lack of limits on existing ones. A full version of this article is available on www.acaa-usa.org/AshatWork.htm. 2 figs.

  10. Chemical Hydride Slurry for Hydrogen Production and Storage

    SciTech Connect

    McClaine, Andrew W.

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston University have demonstrated the technical viability of the process and have provided data for the cost analyses that have been performed. We also concluded that a carbothermic process could also produce magnesium at acceptable costs. The use of slurry as a medium to carry chemical hydrides has been shown during this project to offer significant advantages for storing, delivering, and distributing hydrogen: • Magnesium hydride slurry is stable for months and pumpable. • The oils of the slurry minimize the contact of oxygen and moisture in the air with the metal hydride in the slurry. Thus reactive chemicals, such as lithium hydride, can be handled safely in the air when encased in the oils of the slurry. • Though magnesium hydride offers an additional safety feature of not reacting readily with water at room temperatures, it does react readily with water at temperatures above the boiling point of water. Thus when hydrogen is needed, the slurry and water are heated until the reaction begins, then the reaction energy provides heat for more slurry and water to be heated. • The reaction system can be relatively small and light and the slurry can be stored in conventional liquid fuel tanks. When transported and stored, the conventional liquid fuel infrastructure can be used. • The particular metal hydride of interest in this project, magnesium hydride, forms benign byproducts, magnesium hydroxide (“Milk of Magnesia”) and magnesium oxide. • We have estimated that a magnesium hydride slurry system (including the mixer device and tanks) could meet the DOE 2010 energy density goals. ? During the investigation of hydriding techniques, we learned that magnesium hydride in a slurry can also be cycled in a rechargeable fashion. Thus, magnesium hydride slurry can act either as a chemical hydride storage medium or as a rechargeable hydride storage system. Hydrogen can be stored and delivered and then stored again thus significantly reducing the cost of storing and delivering hydrogen. Further evaluation and development of this concept will be performed as follow-on work under a

  11. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Johnson, R. E.

    2003-08-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to surface trapping of neutrals and ions and depletion of the sodium available for ejection from the surfaces of grains. The change in the sodium exosphere is calculated during one Mercury year taking into account the variations in the solar radiation pressure, the photo-ionization frequency, the solar wind density, the photon and meteoroid flux intensities, and the surface temperature. Line-of-sight column densities at different phase angles, the supply rate of new sodium, average neutral and ion losses over a Mercury year, surface density distribution and the importance of the different processes of ejection are discussed in this paper. The sodium surface density distribution is found to become significantly nonuniform from day to night sides, from low to high latitudes and from morning to afternoon because of rapid depletion of sodium atoms in the surfaces of grains mainly driven by thermal depletion. The shape of the exosphere, as it would be seen from the Earth, changes drastically with respect to Mercury's heliocentric position. High latitude column density maxima are related to maxima in the sodium surface concentration at high latitudes in Mercury's surface and are not necessarily due to solar wind sputtering. The ratio between the sodium column density on the morning side of Mercury's exosphere and the sodium column density on the afternoon side is consistent with the conclusions of Sprague et al. (1997, Icarus 129, 506-527). The model, which has no fitting parameters, shows surprisingly good agreement with recent observations of Potter et al. (2002, Meteor. Planet. Sci. 8, 3357-3374) successfully explaining their velocity and column density profiles vs. heliocentric distance. Comparison with this data allows us to constrain the supply rate of new sodium atoms to the surface. We also discuss the possible origins of the strong high latitude emissions (Potter and Morgan, 1990, Science 248, 835-838; 1997a, Adv. Space Res. 19, 1571-1576; 1997b, Planet. Space Sci. 45, 95-100; Sprague et al., 1998, Icarus 135, 60-68) and the strong variations of the total content of the sodium exosphere on short (Potter et al., 1999, Planet. Space Sci. 47, 1441-1449) and long time scales (Sprague et al., 1997, Icarus 129, 506-527).

  12. Mercury poisoning in a wild mink

    Microsoft Academic Search

    G. WOBESER; M. SWIFT

    1976-01-01

    Mercury poisoning was diagnosed in a clinically-ill wild mink (Mustela vision) on the basis of clinical signs, histopathologic lesions and tissue mercury concentrations. The probable source of mercury was through ingestion of fish from the nearby South Saskatchewan River which is known to be contaminated with mercury. This is believed to be the first documented case of mercury intoxication of

  13. Mercury levels in Wisconsin fish and wildlife

    Microsoft Academic Search

    S. J. Kleinert; P. E. Degurse

    1972-01-01

    Mercury determinations were made on 1824 fish fillet samples representing 139 locations covering 52 of Wisconsin's 72 counties and boundary waters of Lake Michigan, Green Bay, Lake Superior, and the Mississippi River. Mercury levels in fish from waters removed from any known source of mercury use averaged .19 ppm and ranged between .01 and .60 ppm mercury. The highest mercury

  14. Ab-Initio Study of the Group 2 Hydride Anions

    NASA Astrophysics Data System (ADS)

    Harris, Joe P.; Wright, Timothy G.; Manship, Daniel R.

    2013-06-01

    The beryllium hydride (BeH)- dimer has recently been shown to be surprisingly strongly bound, with an electronic structure which is highly dependent on internuclear separation. At the equilibrium distance, the negative charge is to be found on the beryllium atom, despite the higher electronegativity of the hydrogen. The current study expands this investigation to the other Group 2 hydrides, and attempts to explain these effects. M. Verdicchio, G. L. Bendazzoli, S. Evangelisti, T. Leininger J. Phys. Chem. A, 117, 192, (2013)

  15. Neutrino Factory Mercury Vessel

    E-print Network

    McDonald, Kirk

    area ­ Space is available ­ If need 1 s to recool the He in a heat exchanger, need 3 kg, volume = 18 m3 vessel assumed to be cooled with Helium ­ Shielding vessel filled with tungsten beads ­ Mercury vessel-Battelle for the U.S. Department of Energy Cooling Calculations 15 Nov 2012 Helium Properties @ 20C http

  16. Acute mercurial pneumonitis

    PubMed Central

    Milne, James; Christophers, Allen; Silva, Pamela De

    1970-01-01

    Milne, J., Christophers, A., and de Silva, Pamela (1970).Brit. J. industr. Med.,27, 334-338. Acute mercurial pneumonitis. Mercury vapour has been shown to cause acute effects on the lung when inhaled in high concentrations. Four men, exposed to mercury inside a tank, developed, hours later, signs and symptoms of an acute febrile illness with severe pulmonary irritation, characterized by fever, rigors, cough, dyspnoea, and tightness in the chest. A review of the literature revealed that this syndrome had been described and investigated previously in fewer than 20 cases during the past 40 years, and is apparently little known. Fatalities have been described, particularly in children, and necropsy evidence has consistently revealed the pattern of an acute diffuse interstitial pneumonitis, accompanied by profuse fibrinous exudation and erosion of the bronchial and bronchiolar lining. The two common features in all reports are the heating of mercury or the entering into a confined space, or both. Adequate respiratory protection by an efficient air-supplied respirator is mandatory in industrial circumstances of the kind described in this report. PMID:5488692

  17. MERCURY SPECIATION AND CAPTURE

    EPA Science Inventory

    In December 2000, the U.S. Environmental Protection Agency (USEPA) announced its intent to regulate mercury emissions from coal-fired electric utility steam generating plants. Maximum achievable control technology (MACT) requirements are to be proposed by December 2003 and finali...

  18. Mercury and Venus

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students explore Mercury and Venus, the first and second planets nearest the Sun. They learn about the planets' characteristics, including their differences from Earth. Students also learn how engineers are involved in the study of planets by designing equipment and spacecraft to go where it is too dangerous for humans.

  19. MERCURY CEMS: TECHNOLOGY UPDATE

    EPA Science Inventory

    The paper reviews the technologies involved with continuous emission monitors (CEMs) for mercury (Hg) which are receiving incresed attention and focus. Their potential use as a compliance assurance tool is of particular interest. While Hg CEMs are currently used in Europe for com...

  20. APPLIED MERCURY CAPTURE

    EPA Science Inventory

    The first purpose of this project is to complete bench and pilot scale testing of promising mercury sorbents. This work would apply findings from fundamental, mechanistic efforts over the past three years that have developed sorbents which show improved capture of elemental and ...

  1. Mercury Information Clearinghouse

    SciTech Connect

    Chad A. Wocken; Michael J. Holmes; Dennis L. Laudal; Debra F. Pflughoeft-Hassett; Greg F. Weber; Nicholas V. C. Ralston; Stanley J. Miller; Grant E. Dunham; Edwin S. Olson; Laura J. Raymond; John H. Pavlish; Everett A. Sondreal; Steven A. Benson

    2006-03-31

    The Canadian Electricity Association (CEA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals{reg_sign} (CATM{reg_sign}) Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive quarterly information updates that provide a detailed assessment of developments in the various areas of mercury monitoring, control, policy, and research. A total of eight topical reports were completed and are summarized and updated in this final CEA quarterly report. The original quarterly reports can be viewed at the CEA Web site (www.ceamercuryprogram.ca). In addition to a comprehensive update of previous mercury-related topics, a review of results from the CEA Mercury Program is provided. Members of Canada's coal-fired electricity generation sector (ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia Power Inc., Ontario Power Generation, SaskPower, and TransAlta) and CEA, have compiled an extensive database of information from stack-, coal-, and ash-sampling activities. Data from this effort are also available at the CEA Web site and have provided critical information for establishing and reviewing a mercury standard for Canada that is protective of environment and public health and is cost-effective. Specific goals outlined for the CEA mercury program included the following: (1) Improve emission inventories and develop management options through an intensive 2-year coal-, ash-, and stack-sampling program; (2) Promote effective stack testing through the development of guidance material and the support of on-site training on the Ontario Hydro method for employees, government representatives, and contractors on an as-needed basis; (3) Strengthen laboratory analytical capabilities through analysis and quality assurance programs; and (4) Create and maintain an information clearinghouse to ensure that all parties can keep informed on global mercury research and development activities.

  2. Electronic structure, bonding and chemisorption in metallic hydrides

    SciTech Connect

    Ward, J.W.

    1980-01-01

    Problems that can arise during the cycling steps for a hydride storage system usually involve events at surfaces. Chemisorption and reaction processes can be affected by small amounts of contaminants that may act as catalytic poisons. The nature of the poisoning process can vary greatly for the different metals and alloys that form hydrides. A unifying concept is offered, which satisfactorily correlates many of the properties of transition-metal, rare-earth and actinide hydrides. The metallic hydrides can be differentiated on the basis of electronegativity, metallic radius (valence) and electronic structure. For those systems where there are d (transition metals) or f (early actinides) electrons near the Fermi level a broad range of chemical and catalytic behaviors are found, depending on bandwidth and energy. The more electropositive metals (rare-earths, actinides, transition metals with d < 5) tend to strongly chemisorb electrophilic molecules; this is a consequence of the manner in which new bonding states are introduced. More electronegative metals (d >> 5) dissolve hydrogen and form hydrides by an electronically somewhat different process, and as a class tend to adsorb electrophobic molecules. The net charge-transfer in either situation is subtle; however, the small differences are responsible for many of the observed structural, chemical, and catalytic properties in these hydride systems.

  3. Hydride-containing molten salts and their technology implications

    NASA Astrophysics Data System (ADS)

    Liaw, Bor Y.

    1993-03-01

    Hydride-conducting molten salts such as LiH in eutectic LiCl-KCl are attractive electrolyte systems for intermediate-temperature applications. The chemically reducing characteristics of these hydride melts provide a unique method to clean metal surfaces. The high conductivity of these hydride melts makes them the best electrolytes for hydrogen-based energy applications at intermediate temperatures. We will review some earlier work on hydride-conducting molten salts and their potential applications in energy technology. We will also describe some recent work on these hydride-containing molten salts for energy conversion and storage applications, including hydrogen sensing and hydrogen storage, electrochemical characterizations, and thermodynamic and kinetic investigations of metal-hydrogen reactions. More recently, lithium deuteride containing eutectic LiCl-KCl melts have been used for excess heat production by the process of electrolysis to charge deuterium into metal matrix such as Pd and Ti. From these studies we illustrate the prospects of this hydride molten salt technology and its implications for the use in intermediate-temperature electro-chemical energy conversion configurations. It will also reveal some interesting electrochemical aspects involved in the processes.

  4. Effect of niobium additions on initial hydriding kinetics of uranium

    NASA Astrophysics Data System (ADS)

    Li, Ruiwen; Wang, Xiaolin

    2014-06-01

    To study the behavior of hydrogen corrosion at the surface of U, U-2.5 wt%Nb alloy and U-5.7 wt%Nb, a gas-solid reaction system with an in situ microscope was designed. The nucleation and growth of the hydride of the alloy were continuously observed and recorded by a computer. The different characteristics of the hydrides on U metal and U-2.5 wt%Nb showed that the later alloy is more susceptible to hydrogen corrosion than the former. The growth rate of hydride of U-2.5 wt%Nb, calculated by measuring the perimeter of the hydride spots recorded by the in situ microscope, exhibited a reaction temperature dependency in the range of 40-160 °C, for pressure of 0.8 × 105 Pa. An Arrhenius plot for growth rate versus temperature yielded activation energy of 24.34 kJ/mol for the hydriding of U-2.5 wt%Nb alloy. The maximum hydriding rate was obtained at 125 °C, whose thermodynamics reason was discussed.

  5. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Schmidt, Carl A.

    In this dissertation I examine the properties and origins of the most energetic component of Mercury's atmosphere and how it couples to the planet's magnetosphere and space environment. Mercury' s atmosphere consists of particles liberated from its surface that follow ballistic, collisionless trajectories under the influence of gravity and solar radiation pressure. This tenuous atmosphere can be classified as an exosphere where the exobase boundary is the planet's surface. To explain how this exosphere is sustained, a number of theories have been presented: (1) thermal evaporation from the hot surface; (2) photo-desorption of surface materials by UV solar radiation; (3) sputtering by plasma surface interactions; and (4) vaporization of the surface by micro-meteorite impacts. Using a 3-dimensional numerical model, I determine the role each source has in populating the exosphere. New observations of Mercury's escaping atmosphere are presented using novel imaging techniques in which sodium acts as a tracer to identify atmospheric sources. I discuss the implications of these measurements for our understanding of the physical processes at work in the exosphere, and provide a foundation for modeling such processes. For the first time, this work quantifies the variability in the loss of Mercury's sodium as a seasonal effect. My observations show that atmospheric escape can, at times, exceed 1024 Na atoms/s, nearly twice the highest rate previously reported. By forward modeling Mercury' s atmospheric escape, I place new constraints on the source properties and eliminate the prevailing theory that the escaping tail is sputtered from the surface by solar wind ions. The MESSENGER spacecraft has recently discovered that sodium is distributed unevenly over the surface and that the magnetosphere is offset from the planet's center. Using the first model to include these effects, I demonstrate the magnetosphere's influence upon exospheric sources by simulating asymmetries observed in the escaping atmosphere. I conclude that the exosphere is sustained by a combination of micro-meteorite impact vaporization and photo-desorption that is locally enhanced by precipitating ions.

  6. Small Mercury Relativity Orbiter

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  7. MERCURY USAGE AND ALTERNATING IN THE ELECTRICAL AND ELECTRONICS INDUSTRIES

    EPA Science Inventory

    Many industries have already found alternatives for mercury or have greatly decreased mercury use. owever, the unique electromechanical and photoelectric properties of mercury and mercury compounds have made replacement of mercury difficult in some applications. his study was ini...

  8. MERCURY USAGE AND ALTERNATIVES IN THE ELECTRICAL AND ELECTRONICS INDUSTRIES

    EPA Science Inventory

    Many industries have already found alternatives for mercury or have greatly decreased mercury use. However, the unique electromechanical and photoelectric properties of mercury and mercury compounds have made replacement of mercury difficult in some applications. This study was i...

  9. A MODELLING FRAMEWORK FOR MERCURY CYCLING IN LAKE MICHIGAN

    EPA Science Inventory

    A time dependent mercury model was developed to describe mercury cycling in Lake Michigan. The model addresses dynamic relationships between net mercury loadings and the resulting concentrations of mercury species in the water and sediment. The transformations among three mercury...

  10. Review: mercury in waste incineration.

    PubMed

    van Veizen, Daniel; Langenkamp, Heinrich; Herb, Georg

    2002-12-01

    The paper investigates the sources of mercury (Hg) in municipal/industrial waste and the consequences of the presence of this pollutant for the incineration of this waste. About 1990 the average mercury concentration of the feed stream to incinerators was about 4 mg kg(-1). The concentration decreased considerably during the last decade thanks to a considerable reduction of the application of mercury and to the introduction of effective battery return systems. Presently the mercury concentration in municipal SOLID waste is approximately 2 mg kg(-1). During incineration mercury passes practically for 100% in the flue gas. The techniques for mercury removal from flue gases are discussed at the hand of practical examples. It is concluded that there are a number of processes which guarantee mercury concentrations of <50 microg Nm(-3) in the clean gas, the present emission limit concentration. All mercury control processes produce a new solid or liquid waste stream that contains the mercury removed from the flue gas. This stream has to be disposed of as hazardous waste in a qualified landfill. The flue gas from waste incinerators undergoes very rapid dispersion and dilution after leaving the incinerator stack. It follows that the maximum mercury concentration in the ambient air will remain at least five to six orders of magnitude below the lowest MAC value (=Maximum Admissible Concentration in work spaces) and that public health will not be threatened. PMID:12549668

  11. Trialkylborane-Assisted CO2 Reduction by Late Transition Metal Hydrides

    PubMed Central

    Miller, Alexander J. M.; Labinger, Jay A.; Bercaw, John E.

    2011-01-01

    Trialkylborane additives promote reduction of CO2 to formate by bis(diphosphine) Ni(II) and Rh(III) hydride complexes. The late transition metal hydrides, which can be formed from dihydrogen, transfer hydride to CO2 to give a formate-borane adduct. The borane must be of appropriate Lewis acidity: weaker acids do not show significant hydride transfer enhancement, while stronger acids abstract hydride without CO2 reduction. The mechanism likely involves a pre-equilibrium hydride transfer followed by formation of a stabilizing formate-borane adduct. PMID:21909178

  12. Recovery of mercury from acid waste residues

    DOEpatents

    Greenhalgh, Wilbur O. (Richland, WA)

    1989-01-01

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.

  13. Recovery of mercury from acid waste residues

    DOEpatents

    Greenhalgh, W.O.

    1987-02-27

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and thence quenching the reactivity of the nitric acid prior to nitration of the mercury metal. 1 fig.

  14. 21 CFR 872.3700 - Dental mercury.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Prosthetic Devices § 872.3700 Dental mercury. (a) Identification. Dental mercury is a device composed of mercury intended for use as a component of amalgam alloy in the restoration of a dental cavity or a broken tooth....

  15. Designing metal hydride complexes for water splitting reactions: a molecular electrostatic potential approach.

    PubMed

    Sandhya, K S; Suresh, Cherumuttathu H

    2014-08-28

    The hydridic character of octahedral metal hydride complexes of groups VI, VII and VIII has been systematically studied using molecular electrostatic potential (MESP) topography. The absolute minimum of MESP at the hydride ligand (Vmin) and the MESP value at the hydride nucleus (VH) are found to be very good measures of the hydridic character of the hydride ligand. The increasing/decreasing electron donating feature of the ligand environment is clearly reflected in the increasing/decreasing negative character of Vmin and VH. The formation of an outer sphere metal hydride-water complex showing the HH dihydrogen interaction is supported by the location and the value of Vmin near the hydride ligand. A higher negative MESP suggested lower activation energy for H2 elimination. Thus, MESP features provided a way to fine-tune the ligand environment of a metal-hydride complex to achieve high hydridicity for the hydride ligand. The applicability of an MESP based hydridic descriptor in designing water splitting reactions is tested for group VI metal hydride model complexes of tungsten. PMID:24984110

  16. Mercury's sodium exosphere: new insights

    Microsoft Academic Search

    F. Leblanc; R. E. Johnson

    2002-01-01

    We describe the formation of Mercury's sodium exosphere using a 3D Monte Carlo model in which we follow sodium atoms ejected from Mercury's surface by photo desorption, meteoritic vaporization and solar wind sputtering. Comparisons of our results with observations (Potter A.E., Killen R.M. and Morgan T.H., Meteoritics and Planetary Science, 37, 2002) are provided. Averaging over one Mercury year, the

  17. Distribution of Total Mercury and Methyl Mercury in Water, Sediment, and Fish from South Florida Estuaries

    Microsoft Academic Search

    K. Kannan; R. F. Lee; H. L. Windom; P. T. Heitmuller; J. M. Macauley; J. K. Summers

    1998-01-01

    .   Concentrations of total mercury and methyl mercury were determined in sediment and fish collected from estuarine waters\\u000a of Florida to understand their distribution and partitioning. Total mercury concentrations in sediments ranged from 1 to 219\\u000a ng\\/g dry wt. Methyl mercury accounted for, on average, 0.77% of total mercury in sediment. Methyl mercury concentrations were\\u000a not correlated with total mercury

  18. Collisional stripping of Mercury's mantle

    NASA Technical Reports Server (NTRS)

    Benz, Willy; Cameron, A. G. W.; Slattery, Wayne L.

    1988-01-01

    A three-dimensional smoothed-particle hydrocode is the basis of the present numerical simulations of conditions under which a giant collision between a proto-Mercury and a planet one-sixth its size would lead to the loss of most of the silicate mantle of Mercury and thereby account for its anomalously high density. A head-on collision at 20 km/sec, and an off-axis impact parameter of half the radius of the proto-Mercury at 35 km/sec, are approximately equal in damage yielded; both will yield a remnant whose characteristics are those of the present Mercury.

  19. Solubility of hydrogen isotopes in stressed hydride-forming metals

    SciTech Connect

    Coleman, C.E.; Ambler, J.F.R.

    1983-01-01

    Components made from hydride-forming metals can be brittle when particles of hydride are present. The solid solubility limit of hydrogen in these metals needs to be known so that fracture resistance can be properly assessed. Stress affects the solubility of hydrogen in metals. As hydrogen dissolves the metal volume increases, an applied hydrostatic tensile stress supplies work to increase the solubility. Precipitation of hydrides increases the volume further. A hydrostatic tensile stress promotes the formation of hydrides and tends to reduce the terminal solubility. For materials containing hydrogen in solution in equilibrium with hydrides, the effect of stress on the terminal solubility is given. Hydrogen migrates up tensile stress gradients because of the effect of stress on the solubility and solubility limit. Consequently, hydrogen concentrates at flaws. When hydrides are present in the metal matrix, those remote from the flaw tip will preferentially dissolve in favor of those precipitated at the flaw. If the stress is large enough, at some critical condition the hydrides at the flaw will crack. This is delayed hydrogen cracking. Notched and fatigue-cracked cantilever beam specimens (6) (38 x 4 x 3 mm) were machined from the circumferential direction of several cold-worked Zr-2.5 at. % Nb pressure tubes. The chemical compositions had the ranges (in atomic %) Nb - 2.5 to 2.7; O - 0.58 to 0.71; H - 0.018 to 0.18. The effect of test temperature is for a specimen containing 0.13 at. % protium and 0.29 at .% deuterium. Between 505 K and 530 K was less than 1 hr, between 530 K and 537 K it increased to 25.8 h, while at 538 K no cracking was observed up to the 54 h.

  20. Mercury, Vaccines, and Autism

    PubMed Central

    Baker, Jeffrey P.

    2008-01-01

    The controversy regarding the once widely used mercury-containing preservative thimerosal in childhood vaccines has raised many historical questions that have not been adequately explored. Why was this preservative incorporated in the first place? Was there any real evidence that it caused harm? And how did thimerosal become linked in the public mind to the “autism epidemic”? I examine the origins of the thimerosal controversy and their legacy for the debate that has followed. More specifically, I explore the parallel histories of three factors that converged to create the crisis: vaccine preservatives, mercury poisoning, and autism. An understanding of this history provides important lessons for physicians and policymakers seeking to preserve the public’s trust in the nation’s vaccine system. PMID:18172138

  1. Method for mercury refinement

    DOEpatents

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-04-09

    The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

  2. Detecting potassium on Mercury

    NASA Technical Reports Server (NTRS)

    Killen, R. M.; Potter, A. E.; Morgan, T. H.

    1991-01-01

    A critical comment on the work of A.L. Sprague et al. (1990) is presented. It is argued that, in attributing an enhanced emission in the potassium D lines on Oct. 14, 1987 in the equatorial region of Mercury to a diffusion source centered on Caloris Basin, Sprague et al. misinterpreted the data. Sprague et al. present a reply, taking issue with the commenters.

  3. Studies in Boron Hydrides Inorganic Chemistry, Vol. 12,No. 9, 1973 2091

    E-print Network

    Bodner, George M.

    Studies in Boron Hydrides Table Ia Inorganic Chemistry, Vol. 12,No. 9, 1973 2091 B , M logh, log, Illinois 61801 Studies in Boron Hydrides. X. SubstituentEffectsin the Decahydrodecaborate(2-) Ion ALLEN R

  4. The Use of Metal Hydrides for Hydrogen Recovery from Industrial Off-Gas Streams 

    E-print Network

    Rebello, W. J.; Guerrero, P. S.; Goodell, P. D.

    1987-01-01

    Black 242 Chlorine & Caustic 335 Coke Oven Gas 969 Cyclohexane 21 Ethylene (Olefins) 1117 Float Glass 1 Formaldehyde 160 Methanol 103 Petroleum Refining 107 Styrene 88 Total(15 industries) 3634 HYDRIDING ALLOY CHARACTERISTICS THE HYDRIDING...

  5. Associative ionization in mercury

    SciTech Connect

    Folan, L.M.; Sheverev, V.A. [Polytechnic Univ., Brooklyn, NY (United States). Dept. of Applied Mathematics and Physics

    1996-12-31

    Ionization in binary collisions of 6{sup 3}P{sub 0,1,2} excited mercury atoms are of particular importance for the charge particle balance in low temperature mercury-rare gas plasmas, which have found wide and successful application in fluorescent lamps. The principal weak point of existing theoretical models of lighting plasmas is the choice of processes assumed to lead to ionization in collisions of 6{sup 3}P atoms of mercury, and hence to large uncertainties in the cross-section and rate constant data. In fact, the cross-section values used in discharge models differ by more than a factor of ten. Binary 6{sup 3}P{sub 0} collisions, usually neglected, are expected to be of great importance. The authors preset numerical results from the GLOMAC model, showing the variation in fluorescent lamp operating characteristics as the rate constants for ionization in collisions of 6{sup 3}P atoms are varied through the range allowed by existing experimental results. The notable dependencies observed illustrate the need for more accurate experimental data. A novel experimental approach to the measurement of absolute collisional ionization cross-sections, based on a radio frequency ion trap, is proposed.

  6. Inverse potassium hydride: a theoretical study.

    PubMed

    Sawicka, Agnieszka; Skurski, Piotr; Simons, Jack

    2005-02-10

    Results of an experimental study on the unusual "inverse" charge state (H(+)Na(-)) in salts where the H(+) ion is sequestered, combined with our earlier theoretical calculations on an unsequestered model compound (Me(3)N-H(+)...Na(-)), prompted us to further investigate such systems. In particular, we examined Et(3)N-H(+)...K(-) because considerations of the proton affinity of the amine and of the metal-hydride bond strength suggested that this ion-pair complex might be more stable to proton abstraction than was Me(3)N-H(+)...Na(-). In the present work, the ground-state potential energy surface of the Et(3)N-H(+)...K(-) ion pair was examined using second-order Møller-Plesset perturbation theory and 6-311++G basis sets. We found Et(3)N-H(+)...K(-) to be metastable to dissociation with a barrier of 8 kcal mol(-1) (computed at the CCSD(T) level of theory). This barrier indeed is substantially larger than that found earlier for (Me(3)N-H(+)...Na(-)) and suggests that unsequestered inverse-charged H(+)M(-) ion-pair salts may offer a reasonable route to creating high-energy materials if a means for synthesizing them in the laboratory can be designed. PMID:16838965

  7. VOLATILITY OF MERCURY FROM SOILS AMENDED WITH VARIOUS MERCURY COMPOUNDS

    EPA Science Inventory

    A study was conducted to determine the rate of mercury volatilization from soils freshly amended with mercury compounds. Mercuric nitrate, mercuric chloride, mercuric acetate, mercuric oxide, and mercuric sulfide were used in conjunction with three soils: a loamy sand, a sand loa...

  8. The crystal structure and orientation of hydrides formed within ?-Zr (Zr-20 wt% Nb)

    NASA Astrophysics Data System (ADS)

    Khatamian, D.; Swainson, I. P.; Lucas, M. J. W.; Root, J. H.

    1998-04-01

    The structure and orientation of the hydrides formed within ?-Zr have been investigated by neutron diffraction. At room temperature, the hydrides appear to have an orthorhombic structure with Cccm or Pncm symmetry. This structure is stable up to the hydride dissolution temperature. It was also determined that the `close-packed' planes, the (1 1 0) in ?-Zr and the (1 1 1) in the hydride, exhibit similar texture.

  9. Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions

    NASA Astrophysics Data System (ADS)

    Harris, Joe P.; Manship, Daniel R.; Breckenridge, W. H.; Wright, Timothy G.

    2014-02-01

    We study both the rare gas hydride anions, RG-H- (RG = He-Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH- (MIIa = Be-Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be-He complex. While the RG-H- and Be-He species are weakly bound, we show that, as with the previously studied BeH- and MgH- species, the other MIIaH- species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns2) and H-(1s2). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH- species than for RG-H-. Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH- species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H-.

  10. The influence of temperature and yield strength on delayed hydride cracking in hydrided Zircaloy-2

    SciTech Connect

    Efsing, P.; Pettersson, K. [Royal Inst. of Tech., Stockholm (Sweden)

    1996-12-31

    To determine if delayed hydride cracking (DHC) can be the cause of the long axial cracks occasionally found in BWR fuel cladding, a systematic study of DHC in Zircaloy cladding has begun. In the initial stage of the project, a test technique was developed and applied to unirradiated samples of Zircaloy. The present study includes an investigation of the influence of the yield strength and temperature on the crack growth rate and the threshold stress intensity that must be exceeded before cracking begins. Recrystallized (RXA) Zircaloy-2 has been compared to stress relief annealed (SRA) Zircaloy-2 with similar texture and composition. The results show that the crack propagation rate increases with increasing yield strength at similar stress intensity levels by as much as a decade when the yield strength is tripled. The maximum crack propagation rate measured in this study is {approximately}6 {times} 10{sup {minus}7} m/s. The threshold stress intensity, K{sub IH}, was found to decrease with increasing yield stress. The measured threshold values are in the range of 13.5 to 7.5 MPa. These figures are close to theoretically derived values using a critical fracture stress criterion of the hydrides as the limiting factor. The incubation period before cracking begins is found to be longer at 200 C than it is at 300 C.

  11. Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions.

    PubMed

    Harris, Joe P; Manship, Daniel R; Breckenridge, W H; Wright, Timothy G

    2014-02-28

    We study both the rare gas hydride anions, RG-H(-) (RG = He-Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH(-) (MIIa = Be-Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be-He complex. While the RG-H(-) and Be-He species are weakly bound, we show that, as with the previously studied BeH(-) and MgH(-) species, the other MIIaH(-) species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns(2)) and H(-)(1s(2)). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH(-) species than for RG-H(-). Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH(-) species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H(-). PMID:24588166

  12. Metal hydrides: properties and practical applications. review of the works in cis-countries

    Microsoft Academic Search

    V. N Verbetsky; S. P Malyshenko; S. V Mitrokhin; V. V Solovei; Yu. F Shmal’ko

    1998-01-01

    A short review of RandD in the field of hydrogen hydride technologies in Russia and CIS countries is presented. As a result of basic research of physical and chemical features of intermetallic alloys and their hydrides, their structural peculiarities, absorption kinetics, thermal processes, etc., methods have been developed for creation high efficient alloys for different applications in metal hydride technology.

  13. Recent Advance of Hydride Generation–Analytical Atomic Spectrometry: Part II—Analysis of Real Samples

    Microsoft Academic Search

    Zhou Long; Chen Chen; Xiandeng Hou; Chengbin Zheng

    2012-01-01

    Abstract: As an extended discussion of Part I, this review provides a survey of the literature about the elemental and speciation analysis of hydride-forming and non-hydride-forming elements in real samples by using hydride generation–analytical atomic spectrometry based on the recently developed technique summarized in Part I, with emphasis on the sample pretreatment methods and interference elimination.

  14. Recent Advance of Hydride Generation-Analytical Atomic Spectrometry: Part II- Analysis of Real Samples

    Microsoft Academic Search

    Zhou Long; Chen Chen; Xiandeng Hou; Chengbin Zheng

    2012-01-01

    As an extended discussion of Part I, this review provides a survey of the literature about the elemental and speciation analysis of hydride-forming and non-hydride forming elements in real samples by using hydride generation-analytical atomic spectrometry based on the recently developed technique summarized in Part I, with emphesis on the sample pretreatment methods and interference elimination.

  15. The Clean Air Mercury Rule

    SciTech Connect

    Michael Rossler [Edison Electric Institute, Washington, DC (US)

    2005-07-01

    Coming into force on July 15, 2005, the US Clean Air Mercury Rule will use a market-based cap-and-trade approach under Section 111 of the Clean Air Act to reduce mercury emissions from the electric power sector. This article provides a comprehensive summary of the new rule. 14 refs., 2 tabs.

  16. Mercury Removal from Waste Organics

    SciTech Connect

    Cummins, R.L.; Klasson, T.; Taylor, P.A.

    1999-02-28

    Mercury was effectively removed from the oil via sorption using SAMMS.The method was demonstrated on a large scale using ORNL waste oil contaminated with mercury. This technology is ready for further demonstration and implementation when the SAMMS material is available in large quantities.

  17. Mercury in the Chesapeake Bay

    Microsoft Academic Search

    Robert P Mason; Nicole M Lawson; Angie L Lawrence; Joy J Leaner; Jenny G Lee; Guey-Rong Sheu

    1999-01-01

    To elucidate the fate of mercury (Hg) and methylmercury (MMHg) in estuaries we have been studying the biogeochemical cycling of Hg in the Chesapeake Bay and its tributaries. Measurements of total Hg and mercury speciation (MMHg and dissolved gaseous Hg (DGHg)) have been made in the surface waters of the Chesapeake Bay system, including sampling transects into Baltimore Harbor, a

  18. Mercury-Redstone Tail Sections

    NASA Technical Reports Server (NTRS)

    1959-01-01

    In this 1959 photograph, technicians prepare tail sections for Mercury-Redstone vehicles in Building 4706 at Redstone Arsenal in Huntsville, Alabama. Developed by Dr. Wernher von Braun and the rocket team at Redstone, the Mercury-Redstone launched the first two marned U.S. missions.

  19. MERCURY STUDY REPORT TO CONGRESS

    EPA Science Inventory

    This Mercury Study is a Report to Congress prepared by the U.S. Environmental Protection Agency. It fulfills the requirements of section 112(n)(1)(B) of the Clear Air Act, as amended in 1990. The Report provides an assessment of the magnitude of U.S. mercury emissions by source, ...

  20. AC-impedance studies on metal hydride electrodes

    SciTech Connect

    Zhang, W.; Kumar, M.P.S.; Visintin, A.; Srinivasan, S. [Texas A and M Univ., College Station, TX (United States)

    1994-12-31

    The metal hydride (MH{sub x}) electrode is the negative electrode in one of the most advanced rechargeable batteries (i.e. nickel/metal hydride). The objective of this study is to obtain insight on the mechanism of the hydriding/dehydriding reaction in the battery, using the electrochemical impedance spectroscopy (EIS) technique. An equivalent circuit for the MH{sub x} electrode reaction is proposed. The rate capabilities of charge/discharge reaction of MH{sub x} electrode are determined by the kinetics of charge transfer reaction at the alloy surface. Transient and pseudo steady-state analyses (cyclic voltammetry and potential vs. current density behavior) qualitatively and quantitatively support the EIS results. EIS studies on electrodes with (i) three types of binding additives, (ii) varying amounts of active material, and (iii) two types of alloys as active materials demonstrate the usefulness of this technique to develop electrodes with the optimum compositions and structures.

  1. Models for Metal Hydride Particle Shape, Packing, and Heat Transfer

    E-print Network

    Kyle C. Smith; Timothy S. Fisher

    2012-05-04

    A multiphysics modeling approach for heat conduction in metal hydride powders is presented, including particle shape distribution, size distribution, granular packing structure, and effective thermal conductivity. A statistical geometric model is presented that replicates features of particle size and shape distributions observed experimentally that result from cyclic hydride decreptitation. The quasi-static dense packing of a sample set of these particles is simulated via energy-based structural optimization methods. These particles jam (i.e., solidify) at a density (solid volume fraction) of 0.665+/-0.015 - higher than prior experimental estimates. Effective thermal conductivity of the jammed system is simulated and found to follow the behavior predicted by granular effective medium theory. Finally, a theory is presented that links the properties of bi-porous cohesive powders to the present systems based on recent experimental observations of jammed packings of fine powder. This theory produces quantitative experimental agreement with metal hydride powders of various compositions.

  2. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    SciTech Connect

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested under simulated usage and accident conditions. Mitigating the hazards associated with reactive metal hydrides during an accident while finding a way to keep the original capability of the active material intact during normal use has been the focus of this work. These composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride, in this case a prepared sodium alanate (chosen as a representative reactive metal hydride). It was found that the polymerization of styrene and divinyl benzene could be initiated using AIBN in toluene at 70 degC. The resulting composite materials can be either hard or brittle solids depending on the cross-linking density. Thermal decomposition of these styrene-based composite materials is lower than neat polystyrene indicating that the chemical nature of the polymer is affected by the formation of the composite. The char-forming nature of cross-linked polystyrene is low and therefore, not an ideal polymer for hazard mitigation. To obtain composite materials containing a polymer with higher char-forming potential, siloxane-based monomers were investigated. Four vinyl-containing siloxane oligomers were polymerized with and without added styrene and divinyl benzene. Like the styrene materials, these composite materials exhibited thermal decomposition behavior significantly different than the neat polymers. Specifically, the thermal decomposition temperature was shifted approximately 100 degC lower than the neat polymer signifying a major chemical change to the polymer network. Thermal analysis of the cycled samples was performed on the siloxane-based composite materials. It was found that after 30 cycles the siloxane-containing polymer composite material has similar TGA/DSC-MS traces as the virgin composite material indicating that the polymer is physically intact upon cycling. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride in the form of a composite material reduced the inherent hydrogen storage capacity of the material. This

  3. Hydrogen storage in fullerenes and in an organic hydride

    SciTech Connect

    Wang, J.C.; Murphy, R.W.; Chen, F.C. [Oak Ridge National Lab., TN (United States). Energy Div.; Loutfy, R.O.; Veksler, E.; Li, W. [Materials and Electrochemical Research Corp., Tucson, AZ (United States)

    1998-05-29

    While the authors have demonstrated the importance and usefulness of thermal management to the hydrogen storage in fullerenes, their recent effort has concentrated on materials improvement and physical model development. In this paper, they report the results of this effort as follows: (1) Liquid phase hydrogenation of fullerenes indicated that more than 6 wt% capacity can be obtained at 180 C, 350--400 psi; (2) Dehydrogenation of fullerenes hydrides below 225 C was demonstrated using an Ir-based P-C-P pincer complex catalyst; (3) Cyclic hydrogenation and dehydrogenation tests of an organic hydride at 7 wt% capacity were conducted at 180--260 C; and (4) Physical models developed for fullerenes were determined to be applicable to this organic hydride (with much smaller activation energies).

  4. Environmental Geochemistry of Mercury Mines in Alaska

    NSDL National Science Digital Library

    This U.S. Geological Survey fact sheet investigates potential environmental contamination around naturally occurring, mercury-rich mineral deposits in Alaska. Testing of mercury levels in streams and sediments is described, as well as mercury levels in fish downstream from mines and the environmental effects of mercury entering the food chain.

  5. Mercury Emission Measurement at a CFB Plant

    Microsoft Academic Search

    John Pavlish; Jeffrey Thompson; Lucinda Hamre

    2009-01-01

    In response to pending regulation to control mercury emissions in the United States and Canada, several projects have been conducted to perform accurate mass balances at pulverized coal (pc)-fired utilities. Part of the mercury mass balance always includes total gaseous mercury as well as a determination of the speciation of the mercury emissions and a concentration bound to the particulate

  6. Discharge Paths to Mercury-Free Lighting

    Microsoft Academic Search

    Douglas A. Doughty

    1997-01-01

    This talk will begin with a review of where and why mercury is used in various light sources, and why there is a desire to eliminate mercury from these sources. Emphasis will be given to replacing existing mercury-based fluorescent technology, as this sector uses the largest fraction of mercury in the lighting industry. The criteria that need to be satisfied

  7. Development on mercury pump for JSNS

    Microsoft Academic Search

    Hiroyuki Kogawa; Katsuhiro Haga; Takashi Wakui; Masatoshi Futakawa

    2009-01-01

    A permanent magnet rotating type induction pump (PM pump) was developed to provide mercury to a liquid mercury target system in Japan Spallation Neutron Source (JSNS). Mechanical pumps, such as a gear pump and a centrifugal pump, have risk of leakage of mercury from the seal parts. Induction pumps can avoid mercury leakage because they have no seal parts. The

  8. Socioeconomic Consequences of Mercury Use and Pollution

    Microsoft Academic Search

    Edward B. Swain; Paul M. Jakus; Glenn Rice; Frank Lupi; Peter A. Maxson; Jozef M. Pacyna; Alan Penn; Samuel J. Spiegel; Marcello M. Veiga

    2007-01-01

    In the past, human activities often resulted in mercury releases to the biosphere with little consideration of undesirable consequences for the health of humans and wildlife. This paper outlines the pathways through which humans and wildlife are exposed to mercury. Fish consumption is the major route of exposure to methyl- mercury. Humans can also receive toxic doses of mercury through

  9. Sub-millimeter Spectroscopy of Diatomic Hydrides of Astrophysical Interest

    NASA Astrophysics Data System (ADS)

    Halfen, D. T.; Savage, C. S.; Apponi, A. J.; Ziurys, L. M.

    2005-05-01

    One class of interstellar molecules that are unique to the millimeter/far-infrared region of the electromagnetic spectrum are diatomic hydrides. These species have low moments of inertia, and therefore their rotational spectrum lies exclusively at sub-millimeter wavelengths and shorter. They are therefore extremely good targets for space-borne and airborne platforms such as Herschel, SOFIA, and SAFIR. Diatomic hydrides, both neutral (MH) and ionic (MH+) forms, are also basic building blocks of interstellar chemistry. In ionic form, they may be the "hidden" carriers of refractory elements in dense gas. To date, there is very little high resolution data available for many hydride species, in particular the ionic form. In the Ziurys laboratory, we have been conducting studies of metal hydrides using sub-millimeter direct absorption and velocity modulation techniques. We have measured the pure rotational spectrum of AlH (J = 0 -> 1), CrH (N = 0 -> 1), and SH+ (N = 0 -> 1). The hydride neutrals were created in a DC discharge of H2 and metal vapor, generated in a Broida-type oven. In the case of AlH (X1}? {+), the quadrupole hyperfine splitting in the J = 0 -> 1 transition was significantly revised from past measurements. The strongest five hyperfine transitions were recorded for CrH (X6}? {+) in its N = 0 -> 1 transition, the first direct observation of these lines. Spectra of AlD and CrD were measured as well. Finally, the N = 0 -> 1 transition of the SH+ ion (X3}? {-) has been recorded. For this molecule, an AC discharge of H2S and argon or CH3SH and argon was used for the synthesis, and velocity modulation methods were employed to isolate ion signals. Currently, velocity modulation techniques are being developed to study other diatomic hydride ions. Results of these investigations will be reported. This work is supported by NASA Grant NAG5-12719.

  10. Inverse sodium hydride: a theoretical study.

    PubMed

    Sawicka, Agnieszka; Skurski, Piotr; Simons, Jack

    2003-04-01

    A recent experimental investigation in which a salt containing the unusual charge distribution H(+) and Na(-) was synthesized and characterized prompted us to undertake an ab initio theoretical investigation. In the salt synthesized, the H(+) is bound to the nitrogen center of an amine and the Na(-) alkalide is "blocked" from approaching the protonated amine site by steric constraints of a cage structure. Although one expects that the Na(-) would deprotonate an unprotected R(3)N-H(+) cation, we decided to further explore this issue. Using extended atomic orbital basis sets and Møller-Plesset and coupled-cluster treatments of electron correlation, we examined the relative stabilities of the prototype (Me)(3)N + NaH, (Me)(3)N + Na(+) + H(-), (Me)(3)N-H(+) + Na(-), and (Me)(3)N-Na(+) + H(-) as well as the ion pair complexes (Me)(3)N-H(+).Na(-) and (Me)(3)N-Na(+).H(-). The primary focus of this effort was to determine whether the high-energy (Me)(3)N-H(+).Na(-) ion pair, which is the analogue of what the earlier workers termed "inverse sodium hydride", might be stable with respect to proton abstraction under any reasonable solvation conditions (which we treated within the polarized continuum model). Indeed, we find that such ion pairs are metastable (i.e., locally geometrically stable with a barrier to dissociation) for solvents having dielectric constants below approximately 2 but spontaneously decompose into their constituent ions for solvents with higher dielectric constants. We suggest that amines with large proton affinities and/or metals with weaker MH bond strengths should be explored experimentally. PMID:12656631

  11. Cycle performance of a silver-metal hydride cell

    SciTech Connect

    Lipka, S.M.; Nechev, K.S. [Florida Atlantic Univ., Boca Raton, FL (United States). Dept. of Ocean Engineering

    1996-11-01

    Cycling experiments were conducted on a silver oxide-metal hydride cell Previous work on this system determined the influence of electrolyte concentration on rate capability, charge retention and cycle life. The emphasis of this work was placed on enhancing the cycle life of this system. Cells were assembled using sintered silver and AB{sub 5} metal hydride electrodes. Cycle data were collected on flooded cells containing 31 and 45% KOH. A major variable in the improvement of the cycle performance was the silver migration barrier material.

  12. Materials science of Mg-Ni-based new hydrides

    Microsoft Academic Search

    S. Orimo; H. Fujii

    2001-01-01

    .   One of the advantageous functional properties of Mg alloys (or compounds) is to exhibit the reversible hydriding reaction.\\u000a In this paper, we present our systematic studies regarding the relationship between nanometer- or atomistic-scale structures\\u000a and the specific hydriding properties of the Mg-Ni binary system, such as(1) nanostructured (n)-Mg2Ni, (2) a mixture of n-Mg2Ni and amorphous (a)-MgNi,(3) pure a-MgNi, and(4)

  13. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States)] [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)] [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup ?}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  14. Ab-initio study of transition metal hydrides

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh; Shukla, Seema; Dwivedi, Shalini; Sharma, Yamini

    2014-04-01

    We have performed ab initio self consistent calculations based on Full potential linearized augmented plane wave (FP-LAPW) method to investigate the optical and thermal properties of yttrium hydrides. From the band structure and density of states, the optical absorption spectra and specific heats have been calculated. The band structure of Yttrium metal changes dramatically due to hybridization of Y sp orbitals with H s orbitals and there is a net charge transfer from metal to hydrogen site. The electrical resistivity and specific heats of yttrium hydrides are lowered but the thermal conductivity is slightly enhanced due to increase in scattering from hydrogen sites.

  15. Reference Atmosphere for Mercury

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.

    2002-01-01

    The objectives of this three year proposal are: (1) to calculate the likely diffusive flux of Ar and He from the interior of Mercury for representative crustal compositions; (2) compute a reasonable estimate of the fractional escape flux of photoions for the likely range of field conditions; and (3) to calculate the capture rate of solar wind ions into the atmosphere. The morphology of the magnetosphere in response to the solar wind and the IMF is the crucial boundary condition for the flux of ions to the surface. We have tackled problem (1) using a multipath diffusion code, and problems (2) and (3) using a combination of MHD and kinetic plasma dynamics.

  16. Geothermal hazards - Mercury emission

    NASA Technical Reports Server (NTRS)

    Siegel, S. M.; Siegel, B. Z.

    1975-01-01

    Enthusiasm for intensified geothermal exploration may induce many participants to overlook a long-term potential toxicity hazard possibly associated with the tapping of magmatic steam. The association of high atmospheric Hg levels with geothermal activity has been established both in Hawaii and Iceland, and it has been shown that mercury can be introduced into the atmosphere from fumaroles, hot springs, and magmatic sources. These arguments, extended to thallium, selenium, and other hazardous elements, underscore the need for environmental monitoring in conjunction with the delivery of magmatic steam to the surface.

  17. A Mercury Transport and Fate Model for Mass Budget Assessment of Mercury Cycling in Lake Michigan

    EPA Science Inventory

    A mercury mass balance model was developed to describe and evaluate the fate, transport, and biogeochemical transformations of mercury in Lake Michigan. Coupling with total suspendable solids (TSS) and dissolved organic carbon (DOC), the mercury transport and fate model simulates...

  18. Toxicological profile for mercury. Update. Final report

    SciTech Connect

    Canady, R.A.; Rabe, C.S.; Gan, K.

    1994-05-01

    This Statement was prepared to give you information about mercury and to emphasize the human health effects that may result from exposure to it. Mercury has been found in at least 600 of the sites on the NPL. However, the number of NPL sites evaluated for mercury is not known. This information is important because exposure to mercury may cause harmful health effects and because these sites are potential or actual sources of human exposure to mercury.

  19. Elemental mercury exposure in early pregnancy

    SciTech Connect

    Thorp, J.M. Jr.; Boyette, D.D.; Watson, W.J.; Cefalo, R.C. (Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill NC (United States))

    1992-05-01

    We present a case of first-trimester elemental mercury exposure and review the literature to demonstrate that the reproductive toxicity of mercury varies depending on the form of mercury to which one is exposed. It appears that elemental mercury exposure poses less of a reproductive threat than the well-known hazards of exposure to organic mercurials. It is critical to determine the form of exposure when counseling patients at risk.15 references.

  20. High performance Zr-based metal hydride alloys for nickel metal hydride batteries

    SciTech Connect

    Young, R.C.; Ovshinsky, S.R.; Huang, B.; Chao, B.S.; Li, Y.

    2000-07-01

    Based upon Ovonic's multi-element, atomic engineering approach, two families of alloys are being used in commercial Nickel Metal Hydride (NiMH) rechargeable batteries, i.e., the mischmetal (Mm) based AB{sub 5} and Zr based AB{sub 2} alloys. While Mm based alloys are faster to activate, they are limited by a discharge capacity of only 320--340 mAh/g. The Zr based alloy, although slightly slower to activate, provides a much higher discharge capacity. In this paper, the authors first discuss the use of Ovonic's multi-element approach to generate a spectrum of disordered local environments. They then present experimental data to illustrate that through these atomically engineered local environments, they are able to control the hydrogen site occupancy, discharge capacity, kinetics, and surface states. The Zr based alloy with a specific discharge capacity of 465 mAh/g and excellent rate capability has been demonstrated.

  1. Determination of fracture strength of ?-zirconium hydrides embedded in zirconium matrix at high temperatures

    NASA Astrophysics Data System (ADS)

    Kubo, T.; Kobayashi, Y.; Uchikoshi, H.

    2013-04-01

    The fracture strength of ?-zirconium hydrides embedded in a zirconium matrix was determined at temperatures between 25 °C and 250 °C by ring tensile tests using Zircaloy-2 tubes. Essentially all of the present hydrides in the tubes were re-oriented in the radial direction by a temperature cycling treatment and then tensile stress was applied perpendicular to the hydrides to ensure that brittle fracture would occur at the hydrides. The hydrides failed in a brittle manner below 100 °C where-as the zirconium matrix itself underwent ductile fracture without hydride cracking at temperatures above 200 °C under plane stress condition. Brittle fracture of the hydrides continued to occur at temperatures up to 250 °C under plane strain condition, suggesting that the upper limit temperature for hydride fracture, Tupper, was raised by the triaxial stress state under the plane strain condition. The apparent fracture strength of the hydrides, ?hydridef, was determined at temperatures below Tupper from the measured fracture strength of the tubes, making a correction for the compressive transformation stress in the hydrides. ?hydridef was about 710 MPa at temperatures between 25 °C and 250 °C at both plane stress and plane strain conditions. The temperature dependency was very small in this temperature range. Tupper was almost equivalent to the cross-over temperature between ?hydridef and the ultimate tensile strength (UTS), which suggests that, at temperatures above Tupper, the zirconium matrix would undergo ductile fracture before the stress in the hydride is raised above ?hydridef, since UTS is smaller than ?hydridef.

  2. Method for removal and stabilization of mercury in mercury-containing gas streams

    DOEpatents

    Broderick, Thomas E.

    2005-09-13

    The present invention is directed to a process and apparatus for removing and stabilizing mercury from mercury-containing gas streams. A gas stream containing vapor phase elemental and/or speciated mercury is contacted with reagent, such as an oxygen-containing oxidant, in a liquid environment to form a mercury-containing precipitate. The mercury-containing precipitate is kept or placed in solution and reacts with one or more additional reagents to form a solid, stable mercury-containing compound.

  3. Effect of radial hydrides on the axial and hoop mechanical properties of Zircaloy-4 cladding

    NASA Astrophysics Data System (ADS)

    Chu, H. C.; Wu, S. K.; Chien, K. F.; Kuo, R. C.

    2007-05-01

    The effect of radial hydrides on the mechanical properties of stress-relief annealed Zircaloy-4 cladding was studied. Specimens were firstly hydrided to different target hydrogen levels between 100 and 600 wt ppm and then thermally cycled in an autoclave under a constant hoop stress to form radial hydrides by a hydride reorientation process. The effect of radial hydrides on the axial properties of the cladding was insignificant. On the other hand, the cladding ductility measurements decreased as its radial hydride content increased when the specimen was tested in plane strain tension. A reference hydrogen concentration for radial hydrides in the cladding was defined for assessing the fuel cladding integrity based on a criterion of the tensile strength 600 MPa. The reference hydrogen concentration increased with the specimen (bulk) hydrogen concentration to a maximum of ˜90 wt ppm at the bulk concentration ˜300 wt ppm H and then decreased towards higher concentrations.

  4. Mercury content of Illinois soils

    USGS Publications Warehouse

    Dreher, G.B.; Follmer, L.R.

    2004-01-01

    For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

  5. Space weather at Mercury

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Sarantos, M.; Reiff, P. H.

    2004-01-01

    The trajectories of a large number of ions have been traced in Mercury's fields in order to evaluate the effect of photoions on atmospheric neutrals. We present the structure of the Hermean magnetosphere obtained using the [J. Geophys. Res. 98 (1993) 1339-1344] model of an open magnetosphere supplemented with the [Phys. Space Plasmas 14 (1996)] potential solver to represent the convection electric field. We ran our magnetosphere code under boundary conditions appropriate at Mercury to determine the trajectories of 3500 Na photoions in the Hermean magnetosphere. We have counted the number of ions returning at various points on the disk versus the number of ions created at these points. We conclude that photoions can influence the distribution of atmospheric neutrals. We forecast that the column density of neutrals is influenced by photoion production and subsequent photoion loss, and that ions initiate a short-term shift in neutral morphology. Our results reflect the assumption of a predominant dawn to dusk electric field, which will produce a dawnside enhancement in the number of ions reimpacting the surface. The resulting pattern will change as the exact nature of the electric field becomes known. The solar wind ion sputtering effect will further amplify atmospheric patchiness. We have not yet considered the possible effects of neutralization of ions on the nightside.

  6. Cadmium and mercury nephrotoxicity

    NASA Astrophysics Data System (ADS)

    Nicholson, J. K.

    1983-08-01

    Despite increasing attempts to control environmental pollution, changes in the distribution and bioavailability of toxic metals like mercury and cadmium are still occurring. Apart from natural processes, other contributory factors include the gradual spread of industrialization, the use of sewage sludge as a fertilizer and the acidification of Northern Hemisphere ground-water. Animals (including man and domestic varieties) can accumulate harmful concentrations of toxic metals1-5. We therefore looked for damage to the kidneys in seabirds contaminated with mercury and cadmium and made comparisons with kidneys from three other groups of animals: seabirds from an uncontaminated colony, metal-dosed birds and metal-dosed mice. We report here that, comparing all these groups of animals, invididuals with comparatively high levels of metals had nephrotoxic lesions of a similar type and severity. Moreover, the metal concentrations at which damage began and at which biochemical changes could be detected were below those presently considered as relatively safe for humans by the World Health Organization.

  7. Process of forming a sol-gel/metal hydride composite

    DOEpatents

    Congdon, James W. (Aiken, SC)

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  8. Bipolar silver-metal hydride cell studies: Preliminary results

    SciTech Connect

    Reisner, D.E.; Plivelich, R.F.; Klein, M.G. [Electro Energy, Inc., Danbury, CT (United States)

    1995-12-31

    Electro Energy, Inc. (EEI) is developing a patented wafer cell based upon the use of a conductive plastic film as the cell face. Recent studies of silver-metal hydride cells have augmented its principal development of a bipolar Ni-MH battery. Initial wafer cell cycle life test data are reported.

  9. Titanium based Laves phase hydrides with high dissociation pressure

    Microsoft Academic Search

    S. V. Mitrokhin; V. N. Verbetsky

    1996-01-01

    A method for quantitative prediction of the hydrogen sorption properties of Laves phases is proposed. It is based on the empirical rules formulated earlier by Bernauer. The investigation showed that the chosen alloys possess rather high hydrogen dissociation pressure. The isotherms and thermodynamic properties of the hydride phases were determined. The correlation between the experimental and calculated values is discussed.

  10. The cobalt hydride that never was: revisiting Schrauzer's "hydridocobaloxime".

    PubMed

    Lacy, David C; Roberts, Gerri M; Peters, Jonas C

    2015-04-15

    Molecular cobalt-dmg (dmg = dimethylglyoxime) complexes are an important class of electrocatalysts used heavily in mechanistic model studies of the hydrogen evolution reaction (HER). Schrauzer's early isolation of a phosphine-stabilized "[H-Co(III)(dmgH)2P(nBu)3]" complex has long provided circumstantial support for the plausible intermediacy of Co(III)-H species in HER by cobaloximes in solution. Our investigation of this complex has led to a reassignment of its structure as [Co(II)(dmgH)2P(nBu)3], a complex that contains no hydride ligand and dimerizes to form an unsupported Co-Co bond in the solid state. A paramagnetic S = 3/2 impurity that forms during the synthesis of [Co(II)(dmgH)2P(nBu)3] when exposed to adventitious oxygen has also been characterized. This impurity features a (1)H NMR resonance at -5.06 ppm that was recently but erroneously attributed to the hydride resonance of "[H-Co(III)(dmgH)2P(nBu)3]". We draw attention to this reassignment because of its relevance to cobaloxime hydrides and HER catalysis and because Schrauzer's "hydridocobaloxime" is often cited as the primary example of a bona fide hydride that can be isolated and characterized on this widely studied HER platform. PMID:25798900

  11. Aluminium hydride: a reversible material for hydrogen storage.

    PubMed

    Zidan, Ragaiy; Garcia-Diaz, Brenda L; Fewox, Christopher S; Stowe, Ashley C; Gray, Joshua R; Harter, Andrew G

    2009-07-01

    Aluminium hydride has been synthesized electrochemically, providing a synthetic route which closes a reversible cycle for regeneration of the material and bypasses expensive thermodynamic costs which have precluded AlH(3) from being considered as a H(2) storage material. PMID:19557259

  12. Performance analysis of a compressor driven metal hydride cooling system

    Microsoft Academic Search

    S. S. Bedbak; M. Ram Gopal

    2005-01-01

    A compressor-driven metal hydride cooling system is analyzed in terms of its energetic and exergetic efficiencies. Applying the first and second laws of thermodynamics, the system COP, contribution of individual irreversibilities and the second law efficiency of the system are obtained. Effects of important design and operating parameters on system performance are presented. Performance comparison is made between systems working

  13. MERCURY STABILITY IN THE ENVIRONMENT

    SciTech Connect

    John H. Pavlish

    1999-07-01

    The 1990 Clean Air Act Amendments (CAAAs) require the U.S. Environmental Protection Agency (EPA) to determine whether the presence of mercury and 188 other trace substances, referred to as air toxics or hazardous air pollutants (HAPs), in the stack emissions from fossil fuel-fired electric utility power plants poses an unacceptable public health risk (1). The EPA's conclusions and recommendations were presented in two reports: Mercury Study Report to Congress and Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units-Final Report to Congress. The first congressional report addressed both human health and the environmental effects of anthropogenic mercury emissions, while the second report addressed the risk to public health posed by emissions of HAPs from steam electricity-generating units. The National Institute of Environmental Health Sciences is also required by the CAAAs to investigate mercury and determine a safe threshold level of exposure. Recently the National Academy of Sciences has also been commissioned by Congress to complete a report, based the available scientific evidence, regarding safe threshold levels of mercury exposure. Although the EPA reports did not state that mercury controls on coal-fired electric power stations should be required given the current state of the art, they did indicate that EPA views mercury as a potential threat to human health. It is likely that major sources of mercury emissions, including fossil-fired combustion systems, will be controlled at some point. In fact, municipal waste combustion units are already regulated. In anticipation of additional control measures, much research has been done (and continues) regarding the development of control technologies for mercury emitted from stationary sources to the atmosphere. Most approaches taken to date involve sorbent injection technologies or improve upon removal of mercury using existing technologies such as flue gas desulfurization scrubbers, fabric filters, and electrostatic precipitators. Depending on the fly ash chemistry and the form of mercury present in the flue gas, some of these existing technologies can be effective at capturing vapor-phase mercury from the flue gas stream. Although much research has been done on enhancing the removal of mercury from flue gas streams, little research has focused on what happens to the mercury when it is captured and converted and/or transferred to a solid or aqueous solution. The stability (or mobility) of mercury in this final process is critical and leads to the questions, What impact will the increased concentration of mercury have on utilization, disposal, and reuse? and Is the mercury removed from the flue gas really removed from the environment or rereleased at a later point? To help answer these questions, the Energy & Environmental Research Center (EERC) as part of the U.S. Department of Energy (DOE) Base Cooperative Agreement did a series of experiments using thermal desorption and leaching techniques. This report presents the results from these tests.

  14. Sites and Diffusion of Muons in Fcc Metal Hydride Systems.

    NASA Astrophysics Data System (ADS)

    Kempton, James Russell

    1987-09-01

    A positive muon can be considered an isotope of hydrogen due to similarities in spin and charge. For metal hydride systems, the muon enters the sample "as the last hydrogen added," and competes for the same sites as the hydrogen atoms. To observe the site competition and diffusion of both particles (muon and proton), several FCC metal hydrides, TiH_{1.83}, TiH_{1.97}, TiH _{1.99}, YH_{1.77 }, YH_2, ZrH _{1.94}, and LaH_ {2.06}, were studied using transverse -, zero-, and low longitudinal-field muSR. The low temperature region results indicate that the muon predominately occupies octahedral sites for the FCC metal hydrides in this study. The probability for a muon to occupy a tetrahedral site in titanium and zirconium hydrides at these temperatures is proportional to the vacancy concentration. Whereas the probability for T site occupation in yttrium hydride is proportional to the number of protons not occupying these sites which increases with hydrogen concentration. Muon T site occupancy below room temperature for LaH _{2.06} was not observed and was not expected since these sites are occupied by protons. Around 300 K, the muon diffuses over interstitial O sites to vacancies in the H sublattice of TiH_{1.99}. The vibration of the hydrogen lattice is found to be the mechanism responsible for the activation of the muon out of the O site. Above room temperature, the muon occupies tetrahedral sites in yttrium and titanium hydrides. At high temperatures, the field-correlation time for a muon in titanium and yttrium hydrides is approximately one to two orders of magnitude greater than for a proton as measured by NMR. The results of a Monte Carlo simulation indicate that the presence of the muon inhibits the motion of the nearest-neighbor protons at high temperatures. The dynamics of the proton spins are observed by zero- and low longitudinal -field muSR through the oscillation of the muon polarization at long times for a static muon in a T or O site. This observation is not predicted by the Kubo-Toyabe treatment for a stationary muon.

  15. "Cavitation in a Mercury Target"

    SciTech Connect

    West, C.D.

    2000-09-06

    Recent theoretical work on the formation of bubble nucleation centers by energetic particles leads to some reasonably credible calculations of the maximum negative pressure that might be sustained without bubble formation in the mercury target of the Spallation Neutron Source.

  16. Characterization of Mercury's Space Environment

    NASA Astrophysics Data System (ADS)

    Laurenza, Monica; Storini, Marisa; Diego, Piero; Massetti, Stefano

    2015-04-01

    Data from the Helios spacecraft have been revised to identify different solar wind conditions (interplanetary magnetic field intensity, solar wind density, velocity and temperature) at Mercury's location, as they induce critcal changes in the Hermean environment. In particular, the weak magnetic field of the planet and the increasing weight of the interplanetary magnetic field (IMF) BX component at Mercury's orbit, introduce critical differences in the Mercury magnetosphere, such as a strong north-south asymmetry. Different geometries of the Mercury's magnetosphere are also calculated as response to the different solar wind conditions through aToffoletto-Hill modified model (Massetti et al., 2007). Results allow to compute the cutoff rigidities, in order to estimate the energetic charged particle transmission through the Hermean magnetosphere to the specific location of the BepiColombo spacecraft Work partly supported by the Italian Space Agency

  17. Discovery of the Mercury Isotopes

    E-print Network

    D. Meierfrankenfeld; M. Thoennessen

    2010-09-08

    Forty mercury isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  18. Mercury usage and alternatives in the electrical and electronics industries

    Microsoft Academic Search

    B. M. Sass; M. A. Salem; L. A. Smith

    1994-01-01

    Many industries have already found alternatives for mercury or have greatly decreased mercury use. However, the unique electromechanical and photoelectric properties of mercury and mercury compounds have made replacement of mercury difficult in some applications. The study was initiated to identify source reduction and recycling options for mercury in the electrical and electronics industry (SIC 36) and measurement and control

  19. Mercury Toolset for Spatiotemporal Metadata

    NASA Astrophysics Data System (ADS)

    Devarakonda, Ranjeet; Palanisamy, Giri; Green, James; Wilson, Bruce; Rhyne, B. Timothy; Lindsley, Chris

    2010-06-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily)harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  20. Mercury Toolset for Spatiotemporal Metadata

    NASA Technical Reports Server (NTRS)

    Wilson, Bruce E.; Palanisamy, Giri; Devarakonda, Ranjeet; Rhyne, B. Timothy; Lindsley, Chris; Green, James

    2010-01-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily) harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  1. Rapid mercury assays

    SciTech Connect

    Szurdoki, S.; Kido, H.; Hammock, B.D. [Univ. of California, Davis, CA (United States)

    1996-10-01

    We have developed rapid assays with the potential of detecting mercury in environmental samples. our methods combine the simple ELISA-format with the selective, high affinity complexation of mercuric ions by sulfur-containing ligands. The first assay is based on a sandwich chelate formed by a protein-bound ligand immobilized on the wells of a microliter plate, mercuric ion of the analyzed sample, and another ligand conjugated to a reporter enzyme. The second assay involves competition between mercuric ions and an organomercury-conjugate to bind to a chelating conjugate. Several sulfur containing chelators (e.g., dithiocarbamates) and organomercurials linked to macromolecular carriers have been investigated in these assay formats. The assays detect mercuric ions in ppb/high ppt concentrations with high selectivity.

  2. Mercury orbiter transport study

    NASA Technical Reports Server (NTRS)

    Friedlander, A. L.; Feingold, H.

    1977-01-01

    A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

  3. Webcam images of Mercury

    NASA Astrophysics Data System (ADS)

    Hooker, C.

    2006-12-01

    The accompanying images of Mercury were obtained on the morning of 2006 August 19, during a short interval of good seeing. The telescope used was a 10-inch (250mm) Orion Optics (UK) Newtonian on a Vixen GP-DX mount, coupled with a Tele Vue ?5 Powermate to give a sufficiently large image scale. The camera was an ATIK 1 HS II black & white webcam, with a Baader IR-pass filter transmitting wavelengths longer than 685nm. Five movie files in .avi format were recorded over a half-hour period, after which the seeing deteriorated. The observations were made in full daylight: the dark background results from clipping the histogram during processing of the stacked images.

  4. High pressure hydriding of sponge-Zr in steam-hydrogen mixtures

    NASA Astrophysics Data System (ADS)

    Soo Kim, Yeon; Wang, Wei-E.; Olander, D. R.; Yagnik, S. K.

    1997-07-01

    Hydriding kinetics of thin sponge-Zr layers metallurgically bonded to a Zircaloy disk has been studied by thermogravimetry in the temperature range 350-400°C in 7 MPa hydrogen-steam mixtures. Some specimens were prefilmed with a thin oxide layer prior to exposure to the reactant gas; all were coated with a thin layer of gold to avoid premature reaction at edges. Two types of hydriding were observed in prefilmed specimens, viz., a slow hydrogen absorption process that precedes an accelerated (massive) hydriding. At 7 MPa total pressure, the critical ratio of H 2/H 2O above which massive hydriding occurs at 400°C is ˜ 200. The critical H 2/H 20 ratio is shifted to ˜2.5 × 103 at 350°C. The slow hydriding process occurs only when conditions for hydriding and oxidation are approximately equally favorable. Based on maximum weight gain, the specimen is completely converted to ?-ZrH 2 by massive hydriding in ˜5 h at a hydriding rate of ˜10 -6 mol H/cm 2 s. Incubation times of 10-20 h prior to the onset of massive hydriding increases with prefilm oxide thickness in the range of 0-10 ?m. By changing to a steam-enriched gas, massive hydriding that initially started in a steam-starved condition was arrested by re-formation of a protective oxide scale.

  5. Hydride structures in Ti-aluminides subjected to high temperature and hydrogen pressure charging conditions

    NASA Technical Reports Server (NTRS)

    Legzdina, D.; Robertson, I. M.; Birnbaum, H. K.

    1991-01-01

    The distribution and chemistry of hydrides produced in single and dual phase alloys with a composition near TiAl have been investigated by using a combination of TEM and X-ray diffraction techniques. The alloys were exposed at 650 C to 13.8 MPa of gaseous H2 for 100 h. In the single-phase gamma alloy, large hydrides preferentially nucleated on the grain boundaries and matrix dislocations and a population of small hydrides was distributed throughout the matrix. X-ray and electron diffraction patterns from these hydrides indicated that they have an fcc structure with a lattice parameter of 0.45 nm. EDAX analysis of the hydrides showed that they were enriched in Ti. The hydrides were mostly removed by vacuum annealing at 800 C for 24 h. On dissolution of the hydrides, the chemistry of hydride-free regions of the grain boundary returned to the matrix composition, suggesting that Ti segregation accompanied the hydride formation rather than Ti enrichment causing the formation of the hydride.

  6. Mercury ion thruster technology

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Matossian, J. N.

    1989-01-01

    The Mercury Ion Thruster Technology program was an investigation for improving the understanding of state-of-the-art mercury ion thrusters. Emphasis was placed on optimizing the performance and simplifying the design of the 30 cm diameter ring-cusp discharge chamber. Thruster performance was improved considerably; the baseline beam-ion production cost of the optimized configuration was reduced to Epsilon (sub i) perspective to 130 eV/ion. At a discharge propellant-utilization efficiency of 95 percent, the beam-ion production cost was reduced to about 155 eV/ion, representing a reduction of about 40 eV/ion over the corresponding value for the 30 cm diameter J-series thruster. Comprehensive Langmuir-probe surveys were obtained and compared with similar measurements for a J-series thruster. A successful volume-averaging scheme was developed to correlate thruster performance with the dominant plasma processes that prevail in the two thruster designs. The average Maxwellian electron temperature in the optimized ring-cusp design is as much as 1 eV higher than it is in the J-series thruster. Advances in ion-extraction electrode fabrication technology were made by improving materials selection criteria, hydroforming and stress-relieving tooling, and fabrications procedures. An ion-extraction performance study was conducted to assess the effect of screen aperture size on ion-optics performance and to verify the effectiveness of a beam-vectoring model for three-grid ion optics. An assessment of the technology readiness of the J-series thruster was completed, and operation of an 8 cm IAPS thruster using a simplified power processor was demonstrated.

  7. Low-altitude magnetic field measurements by MESSENGER reveal Mercury’s ancient crustal field

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Phillips, Roger J.; Purucker, Michael E.; Anderson, Brian J.; Byrne, Paul K.; Denevi, Brett W.; Feinberg, Joshua M.; Hauck, Steven A.; Head, James W.; Korth, Haje; James, Peter B.; Mazarico, Erwan; Neumann, Gregory A.; Philpott, Lydia C.; Siegler, Matthew A.; Tsyganenko, Nikolai A.; Solomon, Sean C.

    2015-05-01

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury’s crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury’s history. Ancient field strengths that range from those similar to Mercury’s present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury’s crust inferred from MESSENGER elemental composition data.

  8. US mercury recyclers provide expanded process capabilities

    SciTech Connect

    Queneau, P.B.; Smith, L.A.; Royer, M.D.

    1994-02-01

    The article summarizes the treatment capabilities of U.S. plants recovering mercury from a variety of secondaries. There are six non-captive U.S. operations that accept various types of mercury-containing secondaries and wastes for mercury recovery, not including those firms specializing in processing spent lamps. Two of these operations, Adrow Chemical and D.F. Goldsmith Metal and Chemical, specialize in distillation of > or = 99% flowable mercury; non-radioactive mercury assaying > or = 99% Hg is not a listed waste. One operation, Quicksilver Recycling, operates a physical separation circuit followed by distillation; the company's feedstock is primarily electronic scrap. Two firms, Bethlehem Apparatus and Mercury Refining, accept a wide variety of mercury secondaries and wastes for retorting and/or distillation. The only domestic recycler of radioactive mercury materials is NSSI/Recovery Services.

  9. Mercury in smoke from biomass fires

    NASA Astrophysics Data System (ADS)

    Friedli, Hans R.; Radke, Lawrence F.; Lu, Julia Y.

    Litter and green vegetation were collected in 7 locations in the contiguous United States, analyzed for mercury, and burned under controlled conditions at the US Forest Service Fire Science laboratory in Missoula, MT. Among fuels, leaf and 3needle litter contained the highest concentration (up to 71ng/g on dry weight) of mercury. The combustion of litter and green vegetation resulted in essentially complete release of mercury stored in the fuel. Mercury is emitted primarily as elemental mercury, >95% for most burns, with particulate mercury (TPM) accounting for the remainder. From the laboratory experiments we project that mercury emitted from temperate/boreal forest fires and from all biomass burning is an important source components for the atmospheric mercury budget.

  10. 2006 mercury control technology conference. Proceedings

    SciTech Connect

    NONE

    2006-07-01

    A total of 34 papers presented at the conference are available on the NETL website in slide/overhead/viewgraph form. These are in sessions entitled: introduction; sorbent injection; by-product characterization/management; mercury oxidation and Co-removal with FGD systems; and other mercury control technology. Panel discussions were held on: impacts of high SO{sub 3} and balance of plant issues associated with sorbent injection; mercury in coal utilization by-products; and technical performance and cost of mercury control technology other than sorbent injection. The 14 contributions to these three panel discussions plus a summary of each is available. A total of 22 poster papers were presented in the following sections: new 2006 phase III mercury field testing projects; pretreatment of coal; sorbent injection; oxidation of mercury; environmental studies on mercury; and mercury in CUBs. Twelve presentations are available on the internet.

  11. Mercury contamination study for flight system safety

    NASA Technical Reports Server (NTRS)

    Gorzynski, C. S., Jr.; Maycock, J. N.

    1972-01-01

    The effects and prevention of possible mercury pollution from the failure of solar electric propulsion spacecraft using mercury propellant were studied from tankage loading of post launch trajector injection. During preflight operations and initial flight mode there is little danger of mercury pollution if proper safety precautions are taken. Any spillage on the loading, mating, transportation, or launch pad areas is obvious and can be removed by vacuum cleaning soil and chemical fixing. Mercury spilled on Cape Kennedy ground soil will be chemically complexed and retained by the sandstone subsoil. A cover layer of sand or gravel on spilled mercury which has settled to the bottom of a water body adjacent to the system operation will control and eliminate the formation of toxic organic mercurials. Mercury released into the earth's atmosphere through leakage of a fireball will be diffused to low concentration levels. However, gas phase reactions of mercury with ozone could cause a local ozone depletion and result in serious ecological hazards.

  12. Rotating magnetic poles used to pump mercury

    NASA Technical Reports Server (NTRS)

    Ebihara, B. T.; Lowdermilk, W. H.; Vary, A.

    1966-01-01

    Rotating magnetic pump with redesigned pump cell is used for pumping mercury. The modified pump has better electrical continuity, more efficient heat removal, and good wetting characteristics in the mercury flow channel.

  13. MESSENGER observations of Mercury's magnetic field structure

    E-print Network

    Johnson, Catherine L.

    We present a baseline, time-averaged model for Mercury's magnetosphere, derived from MESSENGER Magnetometer data from 24 March to 12 December 2011, comprising the spacecraft's first three Mercury years in orbit around the ...

  14. The curious case of Mercury's internal structure

    E-print Network

    Hauck, Steven A.

    The recent determination of the gravity field of Mercury and new Earth-based radar observations of the planet's spin state afford the opportunity to explore Mercury's internal structure. These observations provide estimates ...

  15. A Temperature Responsive Biopolymer for Mercury Remediation

    E-print Network

    Chen, Wilfred

    such as arsenic or chromium. Introduction Mercury is highly toxic to the nervous system, particularly the developing nervous system of a fetus or young child (1). Because of the lack of knowledge about mercury

  16. Mercury's South Polar Region - Duration: 16 seconds.

    NASA Video Gallery

    This animation shows 89 wide-angle camera (WAC) images of Mercuryâ??s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). Thi...

  17. STATUS ASSESSMENT OF TOXIC CHEMICALS: MERCURY

    EPA Science Inventory

    This report lists the properties, production sources, amounts, and uses of mercury. Mercury pollution figures, sources, health effects, environmental significance, and control technologies are cited. Areas are listed where information is lacking or further study is required....

  18. METHYLATION OF MERCURY IN AGRICULTURAL SOILS

    EPA Science Inventory

    Methylation of applied divalent mercury ion was found to occur in agricultural soils. The production of methylmercury was affected by soil texture, soil moisture content, soil temperature, concentration of the ionic mercury amendment, and time. Methylation was directly proportion...

  19. Method for the removal and recovery of mercury

    DOEpatents

    Easterly, C.E.; Vass, A.A.; Tyndall, R.L.

    1997-01-28

    The present invention is an enhanced method for the removal and recovery of mercury from mercury-contaminated matrices. The method involves contacting a mercury-contaminated matrix with an aqueous dispersant solution derived from specific intra-amoebic isolates to release the mercury from the mercury-contaminated matrix and emulsify the mercury; then, contacting the matrix with an amalgamating metal from a metal source to amalgamate the mercury to the amalgamating metal; removing the metallic source from the mercury-contaminated matrix; and heating the metallic source to vaporize the mercury in a closed system to capture the mercury vapors.

  20. Method for the removal and recovery of mercury

    DOEpatents

    Easterly, Clay E. (Knoxville, TN); Vass, Arpad A. (Oak Ridge, TN); Tyndall, Richard L. (Clinton, TN)

    1997-01-01

    The present invention is an enhanced method for the removal and recovery of mercury from mercury-contaminated matrices. The method involves contacting a mercury-contaminated matrix with an aqueous dispersant solution derived from specific intra-amoebic isolates to release the mercury from the mercury-contaminated matrix and emulsify the mercury; then, contacting the matrix with an amalgamating metal from a metal source to amalgamate the mercury to the amalgamating metal; removing the metallic source from the mercury-contaminated matrix; and heating the metallic source to vaporize the mercury in a closed system to capture the mercury vapors.

  1. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    SciTech Connect

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-03-10

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: 1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs 2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs 3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs 4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs.

  2. Mercury - the hollow planet

    NASA Astrophysics Data System (ADS)

    Rothery, D. A.

    2012-04-01

    Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image from orbit. Although the vent itself may have been excavated partly by explosive volcanism, the most recent event is collapse of a 7 km wide zone in the south centre of the vent. The sharpness of features within this (unmuted either by regolith-forming processes or by fall of volcanic ejecta) suggests that this collapse considerably post-dates the rest of the vent interior. It could reflect a late-stage minor 'throat clearing' explosive eruption, but (in the absence of evidence of associated volcanic ejecta) more likely reflects collapse into a void within the volcanic conduit, itself a result of magma-drainage. A class of 'hole' that is so far conspicuous by its absence on Mercury is sinuous rilles (as opposed to much straighter tectonic grabens) or aligned skylights representing collapsed or partly-collapsed drained lava tubes. Tube-fed flows are to be expected during emplacement of volcanic plains, and it will be surprising if no examples are revealed on MESSENGER and BepiColombo high-resolution images.

  3. ROLE OF MERCURY IN SVARNA VANGA PREPARATION

    PubMed Central

    Sharma; Gyaneshwar; Joshi, d.; Pandey, V.B.; Aryya, N.C.

    1985-01-01

    Svarna Vanga, an important Ayurvedic tin preparation having mercury as one of its ingredients, is mainly indicated in the treatment of Pramehas (genitourinary disorders). What role does mercury play in its preparation is not known. Hence present study has been planned with a view to prepare SvarnaVanga using mercury in different amounts. It was observed that the amount of mercury atleast in half proportion to in tin Kajjali, is considered necessary in making the standard Svarna-Vanga preparation. PMID:22557478

  4. Peat bog records of atmospheric mercury deposition

    Microsoft Academic Search

    Poul Pheiffer Madsen

    1981-01-01

    There have recently been many investigations using atmospheric mercury deposition as an indicator of the impact of industrial development, especially in the Northern Hemisphere. Thus, mosses have been used as indicators of airborne mercury pollution1,2, both wet and dry deposition have been analysed for mercury3,4, and mercury concentrations in 18O\\/16O dated ice core samples from the Greenland Ice Sheet have

  5. Strong Binding Environments for Mercury in Peat

    Microsoft Academic Search

    K. L. Nagy; A. Manceau; J. N. Ryan; G. R. Aiken

    2008-01-01

    Mercury toxicity to humans and wildlife largely originates in bacterial generation of methylmercury in the aquatic environment. Methylmercury may be inhibited from forming if mercury(II) is bound to reduced sulfur in dissolved or solid natural organic matter. Mercury(II)-reduced sulfur bonds are the strongest type of binding between mercury and natural organic matter, but the molecular configurations and binding strengths have

  6. Canadian mercury inventories: the missing pieces.

    PubMed

    Hagreen, L A; Lourie, B A

    2004-07-01

    Research was conducted to determine the significance of the deliberate use of mercury in products in Canada and the associated releases from these sources. Through a combination of literature review and new calculations, the reservoir, flux, and releases of mercury from eight product sources were calculated, and these results compared to historical Canadian inventories. Mercury contributions from the waste sector were also assessed and compared to total Canadian mercury releases and to mercury releases from coal-fired generating stations. Results suggest the use and release of mercury associated with release of mercury associated with its use in products is 4.5 times what previous inventories indicate. Including dental amalgam and sewage sludge, the total releases of mercury to all environmental compartments in Canada totals 20 tonnes per year. This accounts for less than one-half of the 44 tonnes per year of mercury released from mercury waste disposal each year in Canada. Waste mercury contributions from hazardous waste imports, unknown product sources, and incomplete information on the use of mercury in known products may account for this discrepancy. Waste-related mercury releases and transfers for disposal and recycling are 11 times greater than that of electricity generation in Canada. Results indicate that Canadian inventories have underestimated the significance of mercury use and release associated with products, calling into question the current priorities for mercury management. This paper was developed as part of a panel session at the International Joint Commission "Mercury in the Ecosystem" workshop, February 26-27, 2003, Windsor, ON, Canada, as a complement to the information on Canadian Inventories presented by Luke Trip (Senes Consulting, Ottawa, ON, Canada). PMID:15220062

  7. EDITORIAL: Mercury-free discharges for lighting

    Microsoft Academic Search

    M. Haverlag

    2007-01-01

    This special Cluster of articles in Journal of Physics D: Applied Physics covers the subject of mercury-free discharges that are being investigated by different light source researchers, as an alternative to existing mercury-containing lamps. The main driving force to move away from mercury-containing discharge light sources is connected to the environmentally unfriendly nature of mercury. After inhalation or direct contact,

  8. Mercury bioremediation by mercury accumulating Enterobacter sp. cells and its alginate immobilized application

    Microsoft Academic Search

    Arvind Sinha; Sunil Kumar Khare

    The effective microbial remediation of the mercury necessitates the mercury to be trapped within the cells without being recycled\\u000a back to the environment. The study describes a mercury bioaccumulating strain of Enterobacter sp., which remediated mercury from the medium simultaneous to its growth. The transmission electron micrographs and electron\\u000a dispersive X-ray analysis revealed the accumulation of remediated mercury as nano-size

  9. Hydrosilylation of alkynes by Ni(CO)3-stabilized silicon(II) hydride.

    PubMed

    Stoelzel, Miriam; Präsang, Carsten; Inoue, Shigeyoshi; Enthaler, Stephan; Driess, Matthias

    2012-01-01

    Not copy and paste: Although ?-diketiminato ligands have been employed for the stabilization of Ge(II) and Sn(II) hydrides, the corresponding Si(II) hydride is not accessible. However, coordination of silicon(II) to a {Ni(CO)(3)} fragment allowed the isolation of the first Si(II) hydride metal complex 1. This complex was used for the first silicon(II)-based and Ni(0)-mediated, stereoselective hydrosilylation of alkynes. R = phenyl, tolyl. PMID:22105836

  10. Neutral binuclear rare-earth metal complexes with four ??-bridging hydrides.

    PubMed

    Rong, Weifeng; He, Dongliang; Wang, Meiyan; Mou, Zehuai; Cheng, Jianhua; Yao, Changguang; Li, Shihui; Trifonov, Alexander A; Lyubov, Dmitrii M; Cui, Dongmei

    2015-03-25

    The first neutral rare-earth metal dinuclear dihydrido complexes [(NPNPN)LnH2]2 (2-Ln; Ln = Y, Lu; NPNPN: N[Ph2PNC6H3((i)Pr)2]2) bearing ?2-bridging hydride ligands have been synthesized. In the presence of THF, 2-Y undergoes intramolecular activation of the sp(2) C-H bond to form dinuclear aryl-hydride complex 3-Y containing three ?2-bridging hydride ligands. PMID:25713818

  11. Complications from dual roles of sodium hydride as a base and as a reducing agent.

    PubMed

    Hesek, Dusan; Lee, Mijoon; Noll, Bruce C; Fisher, Jed F; Mobashery, Shahriar

    2009-03-20

    Sodium hydride is a common reagent for substrate activation in nucleophilic substitution reactions. Sodium hydride can behave both as a base and as a source of hydride. This dual ability in the presence of an electrophile such as benzyl bromide results in the formation of byproducts when dimethylformamide or acetonitrile are used as solvents for these reactions. The structural nature of these byproducts is revealed in this report. PMID:19215116

  12. Development of a Passively Cooled, Electrically Heated Hydride (PACE) Bed

    SciTech Connect

    Klein, J.E.

    2001-07-26

    A nominal 1500 STP-L Passively Cooled, Electrically heated hydride (PACE) Bed has been developed and tested. Protium absorption rates were measured at pressures of 253, 413, and 680 kPa (1900, 3100, and 5100 torr, respectively) with forced convection cooling air flow rates ranging from 50 to 150 SLPM air. Desorption rates were measured at pressures ranging from 200 to 933 kPa (1500 to 7000 torr) using dual and single 400 watt electric heaters. Methods for estimating absorption rates using a hydride material different than the test material are presented along with a method of estimating tritium absorption rates using protium absorption data. In-Bed Accountability (IBA) tests were preformed using electric heaters to simulate tritium decay and gave a full bed inventory measurement error of 0.6 percent of a full bed.

  13. Synthesis of polyacetylene with titanocene-aluminum hydride catalysts

    SciTech Connect

    Rozova, E.A.; Erofeev, A.B.; Sizov, A.I.; Bulychev, B.M. [M. V. Lomonosov Moscow State Univ., Moscow (Russian Federation)

    1994-09-01

    Heterometallic hydride titanocene-aluminum complexes Cp{sub 2}Ti({mu}-H){sub 2}AlH(X) and (Cp{sub 2}Ti){sub 2}AlH{sub 4}X are highly efficient homogeneous catalysts for acetylene polymerization. The binuclear complex of the composition Cp{sub 2}Ti({mu}-H){sub 2}AlH{sub 2} at 2.2-3.2 M concentrations in ether-toluene solutions exhibits the maximum activity in this reaction. It is believed that the mechanisms of the isomerization of olefins and the polymerization of acetylene are similar and, correspondingly, the compositions and structures of the active sites in both processes are close to each other. The polyacetylene formed with hydride catalysts (mostly the cis-isomer) after doping with iodine has an electrical conductivity of 1.5-2.0{center_dot}10{sup 4} Ohm{sup -1}cm{sup -1}.

  14. Reversible metal–hydride phase transformation in epitaxial films

    NASA Astrophysics Data System (ADS)

    Roytburd, Alexander L.; Boyerinas, Brad M.; Bruck, Hugh A.

    2015-03-01

    Metal–hydride phase transformations in solids commonly proceed with hysteresis. The extrinsic component of hysteresis is the result of the dissipation of energy of internal stress due to plastic deformation and fracture. It can be mitigated on the nanoscale, where plastic deformation and fracture are suppressed and the transformation proceeds through formation and evolution of coherent phases. However, the phase coherency introduces intrinsic thermodynamic hysteresis, preventing reversible transformation. In this paper, it is shown that thermodynamic hysteresis of coherent metal–hydride transformation can be eliminated in epitaxial film due to substrate constraint. Film–substrate interaction leads to formation of heterophase polydomain nanostructure with variable phase fraction which can change reversibly by varying temperature in a closed system or chemical potential in an open system.

  15. Reversible metal-hydride phase transformation in epitaxial films.

    PubMed

    Roytburd, Alexander L; Boyerinas, Brad M; Bruck, Hugh A

    2015-03-11

    Metal-hydride phase transformations in solids commonly proceed with hysteresis. The extrinsic component of hysteresis is the result of the dissipation of energy of internal stress due to plastic deformation and fracture. It can be mitigated on the nanoscale, where plastic deformation and fracture are suppressed and the transformation proceeds through formation and evolution of coherent phases. However, the phase coherency introduces intrinsic thermodynamic hysteresis, preventing reversible transformation. In this paper, it is shown that thermodynamic hysteresis of coherent metal-hydride transformation can be eliminated in epitaxial film due to substrate constraint. Film-substrate interaction leads to formation of heterophase polydomain nanostructure with variable phase fraction which can change reversibly by varying temperature in a closed system or chemical potential in an open system. PMID:25671335

  16. Detecting low concentrations of plutonium hydride with magnetization measurements

    NASA Astrophysics Data System (ADS)

    Kim, Jae Wook; Mun, E. D.; Baiardo, J. P.; Smith, A. I.; Richmond, S.; Mitchell, J.; Schwartz, D.; Zapf, V. S.; Mielke, C. H.

    2015-02-01

    We report the formation of plutonium hydride in 2 at. % Ga-stabilized ?-Pu, with 1 at. % H charging. We show that magnetization measurements are a sensitive, quantitative measure of ferromagnetic plutonium hydride against the nonmagnetic background of plutonium. It was previously shown that at low hydrogen concentrations, hydrogen forms super-abundant vacancy complexes with plutonium, resulting in a bulk lattice contraction. Here, we use magnetization, X-ray, and neutron diffraction measurements to show that in addition to forming vacancy complexes, at least 30% of the H atoms bond with Pu to precipitate PuHx on the surface of the sample with x ˜ 1.9. We observe magnetic hysteresis loops below 40 K with magnetic remanence, consistent with ferromagnetic PuH1.9.

  17. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    EPA Science Inventory

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  18. Mercury and selenium content of Taiwanese seafood

    Microsoft Academic Search

    G. C. Fang; D. H. Nam; N. Basu

    2011-01-01

    Fish consumption is avid in Taiwan (and other Asian nations), but little is known about the mercury and selenium content in local seafood. This paper reports on total mercury, methylmercury and selenium levels from 14 commonly consumed seafood items obtained from Taichung, Taiwan. Mean total mercury concentrations varied nearly 100-fold across species. Fifty per cent of the marlins sampled and

  19. Microbial methylation of mercury in estuarine sediments

    Microsoft Academic Search

    Compeau

    1985-01-01

    Mercury is a common and potentially hazardous pollutant. Although all forms of the element are toxic, alkylated mercurials are particularly toxic and accumulate in living tissues. Factors affecting the availability of mercury and the microorganisms responsible for methylation are described. The methylation of mercuric ions (Hg\\/sup + +\\/) was investigated in pure culture, in estuarine sediments, and as a function

  20. Recycling of Ions in Mercury's Magnetosphere

    Microsoft Academic Search

    Rosemary Killen; Andrew Potter; Menelaos Sarantos; Patricia Reiff

    2005-01-01

    The predominant loss process for exospheric neutral sodium at Mercury is believed to be photoionization. If the ions are lost from the system then sodium must be efficiently re-supplied to the surface by an unknown mechanism. We have mapped the trajectories of low-energy photoions produced on the dayside of Mercury to determine the true loss rate from the Mercury system.

  1. Mercury in the environment: the human element

    Microsoft Academic Search

    R. A. Wallace; W. Fulkerson; W. D. Shults; W. S. Lyon

    1971-01-01

    This review is directed toward an understanding of the uses, sources, distribution, and toxic effects of mercury, and the main emphasis is on man as the distributor and recipient of mercury in the environment. The societal flow of mercury is initially considered. The main conclusion is that there is a need to pay more attention to the social implications of

  2. Mercury's Sodium Exosphere: Magnetospheric Ion recycling

    Microsoft Academic Search

    F. Leblanc; D. Delcourt; R. E. Johnson; M. Liu

    2003-01-01

    The temporal and spatial variability in 3D of Mercury's neutral sodium exosphere and its correlation with the sodium density in Mercury's surface was described for Mercury's motion around the Sun (Leblanc and Johnson 2003). Four processes for ejection of sodium were taken into account: thermal and photon stimulated desorptions, solar wind sputtering and micro-meteoroid vaporization. A model of ion circulation

  3. Canadian mercury inventories: the missing pieces

    Microsoft Academic Search

    L. A Hagreen; B. A Lourie

    2004-01-01

    Research was conducted to determine the significance of the deliberate use of mercury in products in Canada and the associated releases from these sources. Through a combination of literature review and new calculations, the reservoir, flux, and releases of mercury from eight product sources were calculated, and these results compared to historical Canadian inventories. Mercury contributions from the waste sector

  4. Recycling of Ions in Mercury's Magnetosphere

    Microsoft Academic Search

    Rosemary M. Killen; Andrew E. Potter; Menelaos Sarantos; Patricia Reiff

    2003-01-01

    The predominant loss process for exospheric neutral sodium at Mercury is believed to be photoionization. If the ions are lost from the system then sodium must be efficiently re-supplied to the surface by an unknown mechanism. We have mapped the trajectories of low-energy photoions produced on the dayside of Mercury to determine the true loss rate from the Mercury system.

  5. Mercury baseline levels in Flemish soils (Belgium)

    Microsoft Academic Search

    Filip M. G. Tack; Thomas Vanhaesebroeck; Marc G. Verloo; Kurt Van Rompaey; Eric Van Ranst

    2005-01-01

    It is important to establish contaminant levels that are normally present in soils to provide baseline data for pollution studies. Mercury is a toxic element of concern. This study was aimed at assessing baseline mercury levels in soils in Flanders. In a previous study, mercury contents in soils in Oost-Vlaanderen were found to be significantly above levels reported elsewhere. For

  6. Atmospheric Mercury: Emissions, Transport/Fate,

    E-print Network

    important mercury exposure pathway for most humans and wildlife For many aquatic ecosystems, much that may cause neuro-developmental effects; in some sub-populations, fish consumption & mercury exposure, global...) Is "emissions trading" workable and ethical? Is the recently promulgated Clean Air Mercury

  7. MERCURY IN LAKE MICHIGAN ECOSYSTEM COMPONENTS

    EPA Science Inventory

    Mercury is a toxic bioaccumulative substance in aquatic ecosystems. National fish advisories for mercury increased 115% from 1993 to 2001 and fish consumption is now a major health concern. The Lake Michigan Mass Balance Study measured the concentrations of mercury in the atmosph...

  8. Mercury Continuous Emmission Monitor Calibration

    SciTech Connect

    John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

    2009-03-12

    Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry (ID/ICP/MS) performed by NIST in Gaithersburg, MD. The outputs of mercury calibrators are compared to one another using a nesting procedure which allows direct comparison of one calibrator with another at specific concentrations and eliminates analyzer variability effects. The qualification portion of the EPA interim traceability protocol requires the vendors to define calibrator performance as affected by variables such as pressure, temperature, line voltage, and shipping. In 2007 WRI developed and conducted a series of simplified qualification experiments to determine actual calibrator performance related to the variables defined in the qualification portion of the interim protocol.

  9. Cataractogenic effects of a boron hydride disulfide compound.

    PubMed

    Fukui, H N; Iwata, S; Epstein, D L; Merola, L O

    1977-07-01

    The disulfide form but not the sulfhydryl form of a boron hydride compound was found to be cataractogenic. Apparently this compound attaches to the sulfhydryl group of Na-K ATPase in the lens epithelium inactivating this crucial enzyme. The consequence is that a defect in the cation pump activity arises, leading to a rapid influx of Na ions and loss of K ions and marked increase in hydration. These changes are thought to lead to opacification. PMID:141427

  10. Metal-Hydride Films with Switchable Optical Properties

    Microsoft Academic Search

    R. Griessen

    1997-01-01

    We have discovered^1,2 that yttrium-, lanthanum-, and rare-earth-hydride films exhibit spectacular changes in their optical properties when the hydrogen concentration is increased from 0 to 3. For example, a 500 nm thick YH2 film is metallic and shiny, while YH_3-delta is yellowish and transparent. The transition is reversible, fast, and can simply be induced by adding or removing hydrogen from

  11. Titanium-based Laves phase hydrides with high dissociation pressure

    Microsoft Academic Search

    S. V. Mitrokhin; V. N. Verbetsky

    1997-01-01

    The results of the investigation of the hydrogen interaction with Laves phases having general composition Ti1 ? xZrxMn2 ? y ? zCryFez are presented. The hydride phases are characterized by the rather high dissociation pressure of hydrogen at ambient temperature. The experiments were staged in standard Sieverts apparatus at pressures up to 100 atm and in a special apparatus which

  12. Synthesis and properties of multicomponent hydrides with high density

    Microsoft Academic Search

    V. N. Verbetsky; S. V. Mitrokhin; E. A. Movlaev

    1999-01-01

    The results of research of interaction of hydrogen with alloys of Ti–V–M (M=Fe, Co, Ni), Ti–Ta; Zr–Ta; Ti–W; Ti–Ta–W; Zr–Sc; Hf–Sc systems are presented. The study of these materials was carried out in two directions aimed at an increase of hydride density preserving a high content of hydrogen in them and a decrease of synthesis parameters preserving high thermal stability

  13. Reaction between magnesium ammine complex compound and lithium hydride

    Microsoft Academic Search

    Masami Tsubota; Satoshi Hino; Hironobu Fujii; Chie Oomatsu; Masashi Yamana; Takayuki Ichikawa; Yoshitsugu Kojima

    2010-01-01

    The possibility of using ammonia as a hydrogen carrier is examined for the reaction between magnesium ammine complex MgCl2(NH3)6 and lithium hydride LiH. Sample was milled at low temperature of ?40 °C to avoid decomposition of MgCl2(NH3)6 during the milling. The effects of milling time, milling speed (revolutions per minute), and catalysts on hydrogen storage properties were investigated by thermogravimetry, thermal

  14. Measurement and modeling of strain fields in zirconium hydrides precipitated at a stress concentration

    SciTech Connect

    Allen, Gregory B.; Kerr, Matthew; Daymond, Mark R. (Queens)

    2012-10-23

    Hydrogen adsorption into zirconium, as a result of corrosion in aqueous environments, leads to the precipitation of a secondary brittle hydride phase. These hydrides tend to first form at stress concentrations such as fretting flaws or cracks in engineering components, potentially degrading the structural integrity of the component. One mechanism for component failure is a slow crack growth mechanism known as Delayed Hydride Cracking (DHC), where hydride fracture occurs followed by crack arrest in the ductile zirconium matrix. The current work employs both an experimental and a modeling approach to better characterize the effects and behavior of hydride precipitation at such stress concentrations. Strains around stress concentrations containing hydrides were mapped using High Energy X-ray Diffraction (HEXRD). These studies highlighted important differences in the behavior of the hydride phase and the surrounding zirconium matrix, as well as the strain associated with the precipitation of the hydride. A finite element model was also developed and compared to the X-ray strain mapping results. This model provided greater insight into details that could not be obtained directly from the experimental approaches, as well as providing a framework for future modeling to predict the effects of hydride precipitation under varied conditions.

  15. Strain evolution of zirconium hydride embedded in a Zircaloy-2 matrix.

    SciTech Connect

    Kerr, M.; Daymond, M. R.; Holt, R. A.; Almer, J. D.; Queen's Univ.

    2008-01-01

    In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority phase, zirconium hydride, embedded in Zircaloy-2 (<100 wt ppm average hydrogen content). The elastic modulus of the hydride is similar to that of Zircaloy-2. Three regimes are observed: I - elastic, II - post-yield load transfer from Zircaloy-2 to hydride, and III - strain saturation, possibly due to hydride fracture. The interpretation is supported by finite element calculations and scanning electron microscopy of the fracture surface.

  16. Phase changes in the niobium-hydrogen system I: accommodation effects during hydride precipitation

    SciTech Connect

    Makenas, B.J.; Birnbaum, H.K.

    1980-07-01

    The accommodation effects which accompany hydride precipitation were studied in the Nb-H system using T.E.M. Elastic accommodation and punching of prismatic dislocation loops in the solid solution matrix were observed on precipitation. The reversibility of the plastic accommodation processes was studied. Dislocation generation and motion in the hydride were observed during reversion. These observations were related to the volume changes due to hydride formation and to the thermodynamics of the phase change. Direct evidence for the inhibition of hydride precipitation due to trapping at O and N interstitials is presented.

  17. Some new techniques in tritium gas handling as applied to metal hydride synthesis

    SciTech Connect

    Nasise, J.E.

    1988-01-01

    A state-of-the-art tritium Hydriding Synthesis System (HSS) was designed and built to replace the existing system within the Tritium Salt Facility (TSF) at the Los Alamos National Laboratory. This new hydriding system utilizes unique fast-cycling 7.9 mole uranium beds (47.5g of T at 100% loading) and novel gas circulating hydriding furnaces. Tritium system components discussed include fast-cycling uranium beds, circulating gas hydriding furnaces, valves, storage volumes, manifolds, gas transfer pumps, and graphic display and control consoles. Many of the tritium handling and processing techniques incorporated into this system are directly applicable to today's fusion fuel loops. 12 refs., 7 figs.

  18. Structure and properties of complex hydride perovskite materials.

    PubMed

    Schouwink, Pascal; Ley, Morten B; Tissot, Antoine; Hagemann, Hans; Jensen, Torben R; Smr?ok, Lubomír; ?erný, Radovan

    2014-01-01

    Perovskite materials host an incredible variety of functionalities. Although the lightest element, hydrogen, is rarely encountered in oxide perovskite lattices, it was recently observed as the hydride anion H(-), substituting for the oxide anion in BaTiO3. Here we present a series of 30 new complex hydride perovskite-type materials, based on the non-spherical tetrahydroborate anion BH4(-) and new synthesis protocols involving rare-earth elements. Photophysical, electronic and hydrogen storage properties are discussed, along with counterintuitive trends in structural behaviour. The electronic structure is investigated theoretically with density functional theory solid-state calculations. BH4-specific anion dynamics are introduced to perovskites, mediating mechanisms that freeze lattice instabilities and generate supercells of up to 16 × the unit cell volume in AB(BH4)3. In this view, homopolar hydridic di-hydrogen contacts arise as a potential tool with which to tailor crystal symmetries, thus merging concepts of molecular chemistry with ceramic-like host lattices. Furthermore, anion mixing BH4(-)?X(-) (X(-)=Cl(-), Br(-), I(-)) provides a link to the known ABX3 halides. PMID:25490884

  19. Band gap closure in yttrium hydride under high pressure

    NASA Astrophysics Data System (ADS)

    Machida, Akihiko; Nakano, Satoshi

    2005-03-01

    Trivalent rare-earth metals demonstrate spectacular change in electronic properties by hydrogenation. With increase in hydrogen concentration beyond x ˜2.7, yttrium hydride, YHx, shows metal-insulator phase transition with structural change from the fcc to hcp of yttrium metal lattice. Band gap opening due to orbital hybridization between 1s (H) and 4d (Y) has theoretically been proposed for the metal- insulator transition. Theoretical studies have also predicted that the volume reduction by applying hydrostatic pressure would lead to metallization in association with band gap closure. We have investigated structural properties of yttrium hydrides by means of x-ray diffraction and infrared absorption beyond a predicted metallization pressure of ˜18 GPa. Hydride specimen was prepared by hydrogenation reaction of yttrium powder or foil with liquid hydrogen in a diamond anvil cell at room temperature. With increase in pressure beyond ˜10 GPa, the hcp lattice of YH3 transforms gradually to a fcc structure. Infrared spectra show peak position change in the hydrogen vibrational region of 450-1500 cm-1 above ˜11 GPa, corresponding to the x-ray diffraction results. The H-Y bonding state and expected metallization are discussed on the basis of the high pressure experimental results obtained x-ray diffraction and infrared absorption.

  20. Yttrium and lanthanum hydride films with switchable optical properties

    NASA Astrophysics Data System (ADS)

    Huiberts, J. N.; Griessen, R.; Rector, J. H.; Wijngaarden, R. J.; Dekker, J. P.; de Groot, D. G.; Koeman, N. J.

    1996-03-01

    IN many substances, changes in chemical composition, pressure or temperature can induce metal-to-insulator transitions1. Although dramatic changes in optical and electrical properties accompany such transitions, their interpretation is often complicated by attendant changes in crystallographic structure2. Yttrium, lanthanum and the trivalent rare-earth elements form hydrides that also exhibit metal-insulator transitions3-5, but the extreme reactivity and fragility of these materials hinder experimental studies5,6. To overcome these difficulties, we have coated thin films of yttrium and lanthanum with a layer of palladium through which hydrogen can diffuse. Real-time transitions from metallic (YH2 or LaH2) to semiconducting (YH3 or LaH3) behaviour occur in these films during continuous absorption of hydrogen, accompanied by pronounced changes in their optical properties. Although the timescale on which this transition occurs is at present rather slow (a few seconds), there appears to be considerable scope for improvement through the choice of rare-earth element and by adopting electrochemical means for driving the transition. In view of the spectacular changes in optical properties-yttrium hydride, for example, changes from a shiny mirror to a yellow, transparent window-metal hydrides might find important technological applications.

  1. New reactions of terminal hydrides on a diiron dithiolate.

    PubMed

    Wang, Wenguang; Rauchfuss, Thomas B; Zhu, Lingyang; Zampella, Giuseppe

    2014-04-16

    Mechanisms for biological and bioinspired dihydrogen activation and production often invoke the intermediacy of diiron dithiolato dihydrides. The first example of such a Fe2(SR)2H2 species is provided by the complex [(term-H)(?-H)Fe2(pdt)(CO)(dppv)2] ([H1H](0)). Spectroscopic and computational studies indicate that [H1H](0) contains both a bridging hydride and a terminal hydride, which, notably, occupies a basal site. The synthesis begins with [(?-H)Fe2(pdt)(CO)2(dppv)2](+) ([H1(CO)](+)), which undergoes substitution to afford [(?-H)Fe2(pdt)(CO)(NCMe)(dppv)2](+) ([H1(NCMe)](+)). Upon treatment of [H1(NCMe)](+) with borohydride salts, the MeCN ligand is displaced to afford [H1H](0). DNMR (EXSY, SST) experiments on this complex show that the terminal and bridging hydride ligands interchange intramolecularly at a rate of 1 s(-1) at -40 °C. The compound reacts with D2 to afford [D1D](0), but not mixed isotopomers such as [H1D](0). The dihydride undergoes oxidation with Fc(+) under CO to give [1(CO)](+) and H2. Protonation in MeCN solution gives [H1(NCMe)](+) and H2. Carbonylation converts [H1H](0) into [1(CO)](0). PMID:24661238

  2. Electronic structure of ternary rhodium hydrides with lithium and magnesium.

    PubMed

    Becker, Jonas Nils; Bauer, Jessica; Giehr, Andreas; Chu, Pui Ieng; Kunkel, Nathalie; Springborg, Michael; Kohlmann, Holger

    2014-01-21

    Chemical bonding in and electronic structure of lithium and magnesium rhodium hydrides are studied theoretically using DFT methods. For Li3RhH4 with planar complex RhH4 structural units, Crystal Orbital Hamilton Populations reveal significant Rh?Rh interactions within infinite one-dimensional ? 1 [RhH4] stacks in addition to strong rhodium?hydrogen bonding. These metal?metal interactions are considerably weaker in the hypothetical, heavier homologue Na3RhH4. Both compounds are small-band gap semiconductors. The electronic structures of Li3RhH6 and Na3RhH6 with rhodium surrounded octahedrally by hydrogen, on the other hand, are compatible with a classical complex hydride model according to the limiting ionic formula (M+)3[RhH6]3? without any metal?metal interaction between the 18-electron hydridorhodate complexes. In MgRhH, building blocks of the composition (RhH2)4 are formed with strong rhodium?hydrogen and significant rhodium?rhodium bonding (bond lengths of 298 pm within Rh4 squares). These units are linked together to infinite two-dimensional layers ? 2 [(RhH2/2)4] via common hydrogen atoms. Li3RhH4 and MgRhH are accordingly examples for border cases of chemical bonding where the classical picture of hydridometalate complexes in complex hydrides is not sufficient to properly describe the chemical bonding situation. PMID:24372174

  3. Superconductive sodalite-like clathrate calcium hydride at high pressures

    PubMed Central

    Wang, Hui; Tse, John S.; Tanaka, Kaori; Iitaka, Toshiaki; Ma, Yanming

    2012-01-01

    Hydrogen-rich compounds hold promise as high-temperature superconductors under high pressures. Recent theoretical hydride structures on achieving high-pressure superconductivity are composed mainly of H2 fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particle-swam optimization structural search, we show that in the stoichiometry CaH6 a body-centered cubic structure with hydrogen that forms unusual “sodalite” cages containing enclathrated Ca stabilizes above pressure 150 GPa. The stability of this structure is derived from the acceptance by two H2 of electrons donated by Ca forming an “H4” unit as the building block in the construction of the three-dimensional sodalite cage. This unique structure has a partial occupation of the degenerated orbitals at the zone center. The resultant dynamic Jahn–Teller effect helps to enhance electron–phonon coupling and leads to superconductivity of CaH6. A superconducting critical temperature (Tc) of 220–235 K at 150 GPa obtained from the solution of the Eliashberg equations is the highest among all hydrides studied thus far. PMID:22492976

  4. Influence of Mercury

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Aurnou, J. M.; Aubert, J.

    2009-04-01

    Due to the absence of an atmosphere and proximity to the Sun, Mercury's surface temperature varies laterally by several 100s K, even when averaged over long time periods. The dominant variation in time-averaged surface T occurs from pole to equator (~225 K) [1]. The resonant relationship between Mercury's orbit and rotation results in a smaller longitudinal variation (~100 K) [1]. Here we demonstrate, using models of mantle convection in a 3-D spherical shell, that this stationary lateral variation in surface temperature has a small but significant influence on mantle convection and on the lateral variation of heat flux across the core-mantle boundary (CMB). We evaluate the possible observational signature of this laterally-varying convection in terms of boundary topography, stress distribution, gravity and moment of inertia tensor. We furthermore test whether the lateral variation in CMB flux is capable of driving a thermal wind dynamo, i.e., weak dynamo action with no internally-driven core convective motions. For Mercury's mantle we assume a dry olivine rheology including both diffusion creep and disclocation creep with rheological parameters such as activation energy and volume taken from the synthesis of [2]. We assume decaying radiogenic heat sources with the same concentration as in the bulk silicate Earth, and a parameterised model of core cooling. The models are run for 4.5 Ga from a relatively hot initial state with random initial perturbations. We use the code StagYY, which uses a finite-volume discretization on a spherical yin-yang grid and a multigrid solver [3]. Results in spherical axisymmetric geometry, compare a case with constant surface temperature to one with a latitude-dependent surface temperature. The system forms about 3 convection cells from pole to equator. Although the results look similar to first order, in the latitude-dependent case the convection is noticably more sluggish and colder towards the pole. In CMB flux, both cases display large oscillations due to convection cells. A pole-to-equator trend is superimposed on this for the case with laterally-varying surface temperature. Although the amplitude of this long-wavelength variation is smaller than that of the within-cell variation, its long-wavelength nature might be effective in driving thermal winds in the core. Results in a full 3-D spherical shell indicate that convection adopts a cellular structure with a polygonal network of downwellings and plume-like upwellings, as is usually obtained for stagnant lid convection, for example, in the recent 3-D spherical Mercury models of [4]. This is in notable contrast to the models of [5], in which linear upwellings were obtained. This difference could be because the initial perturbations used by [5] used a small number of low-order spherical harmonics, i.e., a long-wavelength pattern with particular symmetries, whereas our initial perturbations are random white noise. The origin of this difference requires further investigation. The pattern of CMB heat flux shows a strong l=2, m=0 pattern, again with superimposed small-scale variations due to convection cells. The surface geoid displays an very dominant (2,0) pattern, which would be a strong diagnostic of this behaviour. These models are being further analysed for boundary topography and stress distribution. Models of planetary dynamos have traditionally depended upon the concept that secular cooling and internal radioactive decay are responsible for genererating convective fluid motions within the core [e.g. 6]. Some models, of Earth's dynamo in particular, also include thermal winds --shear flows driven by heat flux variations along the core-mantle boundary -- that modify the dynamo process [e.g. 7]. We have now shown, following the work of [8], that thermal winds themselves are capable of driving dynamo action in planetary cores (Fig. 4). In fully self-consistent, three-dimensional models, we find that thermal wind dynamos do not require a net heat flux to emanate from the core and can operate even when the core fluid is neutrally stratifie

  5. Hydrogen storage and evolution catalysed by metal hydride complexes.

    PubMed

    Fukuzumi, Shunichi; Suenobu, Tomoyoshi

    2013-01-01

    The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-?N(2))benzoic acid-?C(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of ?-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (? > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes. PMID:23080061

  6. Anthropogenic mercury emissions in China

    NASA Astrophysics Data System (ADS)

    Streets, David G.; Hao, Jiming; Wu, Ye; Jiang, Jingkun; Chan, Melissa; Tian, Hezhong; Feng, Xinbin

    An inventory of mercury emissions from anthropogenic activities in China is compiled for the year 1999 from official statistical data. We estimate that China's emissions were 536 (±236) t of total mercury. This value includes open biomass burning, but does not include natural sources or re-emission of previously deposited mercury. Approximately 45% of the Hg comes from non-ferrous metals smelting, 38% from coal combustion, and 17% from miscellaneous activities, of which battery and fluorescent lamp production and cement production are the largest. Emissions are heaviest in Liaoning and Guangdong Provinces, where extensive smelting occurs, and in Guizhou Province, where there is much small-scale combustion of high-Hg coal without emission control devices. Emissions are gridded at 30×30 min spatial resolution. We estimate that 56% of the Hg in China is released as Hg 0, 32% as Hg 2+, and 12% as Hg p. Particulate mercury emissions are high in China due to heavy burning of coal in residential and small industrial settings without PM controls. Emissions of Hg 2+ from coal-fired power plants are high due to the absence of flue-gas desulfurization units, which tend to dissolve the soluble divalent mercury. Metals smelting operations favor the production of elemental mercury. Much of the Hg is released from small-scale activities in rather remote areas, and therefore the activity levels are quite uncertain. Also, emissions test data for Chinese sources are lacking, causing uncertainties in Hg emission factors and removal efficiencies. Overall, we calculate an uncertainty level of ±44% (95% confidence interval) in the estimate of total emissions. We recommend field testing of coal combustors and smelters in China to improve the accuracy of these estimates.

  7. How is Mercury's dynamo powered?

    NASA Astrophysics Data System (ADS)

    Cox, G. A.; Delbridge, B. G.; Irving, J. C. E.; Matsui, H.; McDonough, W. F.; Rose, I.; Shahar, A.; Wahl, S. M.

    2014-12-01

    One of the more surprising findings of the MESSENGER spacecraft is the confirmation that the smallest terrestrial planet has an internally generated, dipolar magnetic field, which is likely driven by a combination of thermal and compositional buoyancy sources. This observation places constraints on the thermal and energetic state of Mercury's large iron core and on mantle dynamics because dynamo operation is strongly dependent on the amount of heat extracted from the core by the mantle. However, other observations point to several factors that should inhibit a present-day dynamo. These include physical constraints on a thin, possibly non-convecting mantle, as well as properties of liquid iron alloys that promote compositional stratification in the core. We consider a range of self-consistent internal structures, core compositions and thermal evolution models that are also consistent with observational constraints, and assess the circumstances under which a dynamo is permitted to operate in Mercury's core. We present the thermal evolution models, 1D parameterized convection models and planetary entropy calculations. We attempt to account for the large uncertainties on some parameters by considering various end member cases. We examine the thermal and magnetic implications of a long-lived lateral temperature difference resulting from Mercury's orbital resonance and how it may play a role in driving the planetary dynamo. We compare simulations of mantle heat flow using the ASPECT convection code to predictions from the parameterized models and produce heat flow maps at the CMB. To represent fluid dynamics and magnetic field generation inside Mercury's core, a numerical dynamo model is performed by using the obtained heat flux maps. Lastly, we also investigate the seismic observability of the different structural models of Mercury to determine the extent to which any future single-seismometer mission will be able to provide alternative insights into Mercury's internal dynamics. This study was initiated at the 2014 CIDER summer program on the dynamics of planetary interiors.

  8. The charged Particle Environment of Mercury

    NASA Astrophysics Data System (ADS)

    Zurbuchen, T.; Koehn, P.; Fisk, L.; Gombosi, T.

    The particle environment of Mercury is being examined using 3D MHD simulations and ray-tracing studies of pickup ions in the Mercury environment. The MHD simulations will study the time-dependence of the Hermean magnetosphere that is constantly forced by the varying solar wind conditions. We will focus on realistic solar wind conditions and the direct access of heliospheric particles to the surface of the planet. We then focus on sputtered Mercury particles and their transport through Mercury's magnetosphere. This talk will present predictions of particle fluxes and energization processes, both of which are highly relevant for future missions to Mercury, such as MESSENGER, and Bepi-Colombo

  9. Electrochemical determination of mercury: a review.

    PubMed

    Martín-Yerga, Daniel; González-García, María Begoña; Costa-García, Agustín

    2013-11-15

    Mercury is a metal that has been extensively studied, in large part due to its high toxicity. Therefore, mercury levels must be monitored in different sample types using analytical methods. This review summarizes the electrochemical methods that have been used for mercury analysis in a variety of samples. A critical evaluation of the methods and electrode materials employed for mercury analysis is presented according to the following classifications: bare electrodes, chemically modified electrodes and nanostructured electrodes. The advantages and disadvantages of each type of electrode material regarding mercury analysis are also presented. PMID:24148521

  10. Measuring mercury in coastal fog water

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-04-01

    Mercury, a heavy metal neurotoxin, accumulates in sea life, in some cases reaching levels that make seafood unsafe for humans to eat. How mercury gets into aquatic organisms is debated, but part of the pathway could include mercury carried in precipitation, including rain, snow, and fog. The contribution of mercury in fog water in particular is not well known, especially in foggy coastal areas such as coastal California. To learn more, Weiss-Penzias et al. measured total mercury and monomethyl mercury concentrations in fog water and rainwater samples taken from four locations around Monterey Bay, California, during spring and summer 2011. They found that the mean monomethyl mercury concentrations in their fog water samples were about 34 times higher than the mean concentrations in their rainwater samples. Therefore, the authors believe that fog is an important, previously unrecognized source of mercury to coastal ecosystems. They also explored potential sources of mercury, finding that biotically formed monomethyl mercury from oceanic upwelling may contribute to monomethyl mercury in fog. (Geophysical Research Letters, doi:10.1029/2011GL050324, 2012)

  11. ULF waves at Mercury

    NASA Astrophysics Data System (ADS)

    Kim, E. H.; Boardsen, S. A.; Johnson, J.; Slavin, J. A.

    2014-12-01

    Ion cyclotron frequency range waves (or electromagnetic ion cyclotron wave, EMIC) have been often observed at Mercury's magnetospheres. The previous statistical study showed the magnetic compressional component is dominant near the magnetic equator and the transition from compressional to transverse dominance occurs roughly at magnetic latitudes of ±20?. Because the observed waves also often show linearly polarization, the field-line resonance in the single or multiple ion plasmas have been suggested to discuss such waves. On the other hand, electromagnetic ion Bernstein wave (IBW) is also suggested because of strong power of compressional component. In this talk, we will address both field-line resonance and electromagnetic IBWs in order to discuss the ULF waves detected from MESSENGER. We adopted 2D full-wave code that recently developed at Princeton Plasma Physics Laboratory. When compressional fast waves are launched in the outer magnetosphere, the waves propagate to inner magnetosphere and strong field-aligned waves are mode-converted from the incoming compressional waves. Such mode-converted waves globally oscillate and have strong transverse components. Near the magnetic equator, due to mixture of incoming compressional waves and mode-converted field-line resonance, magnetic compressional component is dominant while transverse component is dominant off the equator, which is consistent with statistical study. We also used warm plasma ray-tracing to explore the propagation of the IBW mode in a dipole magnetic field and found that the electromagnetic IBWs are highly unstable to the proton loss cone distribution function and the wave's group velocity is highly field aligned. The wavelength of this mode is on the order of 100 km. We also discovered that as the waves propagate they can become highly compressional even in a moderate proton beta ~0.05 to 0.54 plasma, which is also consistent with observations.

  12. Mercury speciation in tailings of the Idrija mercury mine

    Microsoft Academic Search

    Harald Biester; Mateja Gosar; German Müller

    1999-01-01

    Five hundred years of mercury (Hg) mining activity in Idrija, Slovenia caused widespread Hg contamination. Besides Hg emissions from the ore smelter, tailings have been found to be the major source of river sediment contamination. In the present study, solid phase binding forms and the aqueous mobility of Hg have been investigated in tailings of the Idrija Hg mine by

  13. Combined on-board hydride slurry storage and reactor system and process for hydrogen-powered vehicles and devices

    DOEpatents

    Brooks, Kriston P; Holladay, Jamelyn D; Simmons, Kevin L; Herling, Darrell R

    2014-11-18

    An on-board hydride storage system and process are described. The system includes a slurry storage system that includes a slurry reactor and a variable concentration slurry. In one preferred configuration, the storage system stores a slurry containing a hydride storage material in a carrier fluid at a first concentration of hydride solids. The slurry reactor receives the slurry containing a second concentration of the hydride storage material and releases hydrogen as a fuel to hydrogen-power devices and vehicles.

  14. How does climate change influence Arctic mercury?

    PubMed

    Stern, Gary A; Macdonald, Robie W; Outridge, Peter M; Wilson, Simon; Chételat, John; Cole, Amanda; Hintelmann, Holger; Loseto, Lisa L; Steffen, Alexandra; Wang, Feiyue; Zdanowicz, Christian

    2012-01-01

    Recent studies have shown that climate change is already having significant impacts on many aspects of transport pathways, speciation and cycling of mercury within Arctic ecosystems. For example, the extensive loss of sea-ice in the Arctic Ocean and the concurrent shift from greater proportions of perennial to annual types have been shown to promote changes in primary productivity, shift foodweb structures, alter mercury methylation and demethylation rates, and influence mercury distribution and transport across the ocean-sea-ice-atmosphere interface (bottom-up processes). In addition, changes in animal social behavior associated with changing sea-ice regimes can affect dietary exposure to mercury (top-down processes). In this review, we address these and other possible ramifications of climate variability on mercury cycling, processes and exposure by applying recent literature to the following nine questions; 1) What impact has climate change had on Arctic physical characteristics and processes? 2) How do rising temperatures affect atmospheric mercury chemistry? 3) Will a decrease in sea-ice coverage have an impact on the amount of atmospheric mercury deposited to or emitted from the Arctic Ocean, and if so, how? 4) Does climate affect air-surface mercury flux, and riverine mercury fluxes, in Arctic freshwater and terrestrial systems, and if so, how? 5) How does climate change affect mercury methylation/demethylation in different compartments in the Arctic Ocean and freshwater systems? 6) How will climate change alter the structure and dynamics of freshwater food webs, and thereby affect the bioaccumulation of mercury? 7) How will climate change alter the structure and dynamics of marine food webs, and thereby affect the bioaccumulation of marine mercury? 8) What are the likely mercury emissions from melting glaciers and thawing permafrost under climate change scenarios? and 9) What can be learned from current mass balance inventories of mercury in the Arctic? The review finishes with several conclusions and recommendations. PMID:22104383

  15. Mercury spills require special cleanup methods, protection

    SciTech Connect

    Ceaser, A.V. [Omni/ajax, Great Meadows, NJ (United States)

    1996-01-01

    Cleaning up liquid mercury usually involves one or two chemical processes--insolubilization and/or amalgamation. Both turn liquid mercury into a non-vaporizing form. Insolubilization most often involves turning mercury into a sulfide. Amalgamation combines liquid mercury with metal powder to produce a solid, non-mobile form. The minimum protection requires for working on mercury-spill cleanups involves equipment specially designed for mercury exposures, including respirators, gloves, goggles and shoe covers. In some cases, full-body protection may be required. Other equipment includes gold-film-type mercury-vapor detectors, probably the most sensitive and efficient units available for mercury cleanups; gas detection tubes; and high-intensity halogen lamps, which often reveal liquid mercury to the eye. If the mercury spill is in a confined area, it should be ventilated immediately. Indoor heating systems should be shut off to reduce vaporization. If an amalgamating powder is not available immediately, responders can cover the suspected area with polyethylene sheeting or spray, and apply an acrylic wash over the surface. In most soil contamination cases, the mercury is at or close to the surface. The contaminated soil should be excavation to 50% beyond the depth of contamination to ensure complete removal. This excavated soil can be taken off site, and the mercury removed through distillation or through magnetic means, using amalgamating powder. The latter process involves slurring the contaminated soil in water and stirring in the magnetic powder. In some cases, a mild acid may have to be added to maintain a pH of no less than 4 or higher than 6. After adequate mixing, the amalgamated mercury may be removed using a plastic-covered magnet as described previously. The soil should be tested on-site for any remaining mercury. In all procedures, the use of corrosion-resistant, plastic equipment should be employed.

  16. Abatement of Gas-Phase Mercury—Recent Developments

    Microsoft Academic Search

    Benjaram M. Reddy; Naga Durgasri; Thallada Vinod Kumar; Suresh K. Bhargava

    2012-01-01

    Among various pollutants, mercury has a significant impact on the environment, human beings, and wildlife with its different forms, namely, elemental mercury (Hg), oxidized mercury (Hg), and particle-bound mercury (Hgp). Mercury dispersions mainly occur from coal burning, which is the world's major energy source. Among the three forms, Hg and Hgp are relatively easy to remove from the flue gas

  17. Developmental study of mercury effects on the fruit fly (Drosophila melanogaster)

    PubMed Central

    Abnoos, Hamideh; Mahdavi-shahri, Naser; Haddad, Farhang; Jalal, Razieh

    2013-01-01

    Environmental pollution caused by heavy metals such as mercury is one of the most important human problems. It might have severe teratogenic effects on embryonic development. Some pharmacological and physiological aspects of fruit flies (Drosophila melanogaster) are similar to humans. So the stages of egg to adult fruit fly, as a developmental model, were employed in the study. Wild adult insects were maintained in glass dishes containing standard medium at 25 °C in complete darkness. Five pairs of 3-day old flies were then transferred to standard culture dishes containing different concentrations of mercury ion. They were removed after 8 hours. We considered the following: The rate of larvae becoming pupae and pupae to adults; the time required for the development; the hatching rate in the second generation without mercury in the culture; the morphometric changes during development in both length and width of the eggs through two generations; larvae, pupae and adult thorax length and width. The results showed that mercury in culture (20–100 mg/l) increase the duration of larvae (p<0.01) and pupae (p<0.01) development, the rate of larvae becoming pupae (p<0.001); pupae maturation (p<0.05), the hatching rate (p<0.01), the length (p<0.05) and width of larvae (p<0.01) and pupae (p<0.001) and the length in the adult thorax (p<0.01) decreased significantly. There was no effect upon the size of eggs. There were also no larvae hatching in concentrations of 200 mg/l of mercury. Negative effects of mercury as a heavy metal are possibly due to the interference of this metal in cellular signaling pathways, such as: Notch signaling and protein synthesis during the period of development. Since it bonds chemically with the sulfur hydride groups of proteins, it causes damage to the cell membrane and decreases the amount of RNA. This is the cause of failure of many enzyme mechanisms. PMID:24170977

  18. An investigation on structure, deformation and fracture of hydrides in titanium with a large range of hydrogen contents

    Microsoft Academic Search

    C. Q. Chen; S. X. Li; H. Zheng; L. B. Wang; K. Lu

    2004-01-01

    The deformation and fracture behaviors of ? hydrides in cyclic strained titanium containing 350, 720 and 930 ppm hydrogen were investigated and compared to that of ? hydrides in 77 ppm hydrogen specimens. It was found that the ? and ? hydrides, respectively, in 77 and 350 ppm hydrogen specimens could be plastically deformed readily along with the matrix without

  19. Optimization of dimethyltin chloride determination by hydride generation gas phase molecular absorption spectrometry using a central composite design

    Microsoft Academic Search

    Jesús Sanz; Margarita Pérez; Mar??a T. Mart??nez; Mar??a Plaza

    2000-01-01

    A factorial design is applied to the optimization of the determination of dimethyltin chloride by hydride generation gas phase molecular absorption spectrometry (HG-GPMAS). A method is described for the determination of dimethyltin chloride after conversion into gaseous dimethyltin hydride by adding a sodium tetrahydroborate (III) solution. The hydride generated is collected in a liquid nitrogen cryogenic trap. This is revolatilized,

  20. Evaluation of the delayed hydride cracking mechanism for transgranular stress corrosion cracking of magnesium alloys

    Microsoft Academic Search

    N. Winzer; A. Atrens; W. Dietzel; G. Song; K. U. Kainer

    2007-01-01

    This paper evaluates the important elements of delayed hydride cracking (DHC) for transgranular stress corrosion cracking (TGSCC) of Mg alloys. A DHC model was formulated with the following components: (i) transient H diffusion towards the crack tip driven by stress and H concentration gradients; (ii) hydride precipitation when the H solvus is exceeded; and (iii) crack propagation through the extent

  1. Hydrogen storage as a hydride. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    NONE

    1996-04-01

    The bibliography contains citations concerning the storage of hydrogen in various metal hydrides. Binary and intermetallic hydrides are considered. Specific alloys discussed are iron-titanium, lanthanum-nickel, magnesium-copper, and magnesium-nickel among others. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  2. Hydrogen storage as a hydride. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    NONE

    1997-06-01

    The bibliography contains citations concerning the storage of hydrogen in various metal hydrides. Binary and intermetallic hydrides are considered. Specific alloys discussed are iron-titanium, lanthanum-nickel, magnesium-copper, and magnesium-nickel among others. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  3. Insights into the origin of the separation selectivity with silica hydride adsorbents.

    PubMed

    Kulsing, Chadin; Nolvachai, Yada; Marriott, Philip J; Boysen, Reinhard I; Matyska, Maria T; Pesek, Joseph J; Hearn, Milton T W

    2015-02-19

    In this study, the surface properties of type-B silica have been compared with an unmodified silica hydride phase, a diamond hydride phase and silica hydride phases modified with bidentate anchored octyl (BDC8), bidentate anchored octadecyl (BDC18), phenyl and cholesteryl groups. Atomic distributions of the surface elemental composition of each type of stationary phase were determined using energy-dispersive X-ray spectroscopy. For the type-B silica, unmodified silica hydride, diamond hydride as well as BDC18 and cholesteryl silica hydride phases, the increase in carbon contents correlated with more negative surface ? potential values (R(2) = 0.92). The origin of these more negative ? potentials has been evaluated with mobile phases up to 100% (v/v) methanol content, with this property attributed to either an increase in the amount of adsorbed hydroxide ions or a decrease in the amount of adsorbed protons on the surfaces modified silica hydride phases of higher carbon content. This property of chemically modified silica hydride phases is in accordance with the unique propensity for hydroxide ions to be preferentially adsorbed onto hydrophobic surfaces of low permittivity and effects due to the specific accumulated water molecules associated with the electrical interfacial double layer of the adsorbent. PMID:25656442

  4. INFLUENCE OF HYDRIDE MICROSTRUCTURE ON THROUGH-THICKNESS CRACK GROWTH IN ZIRCALOY-4 SHEET

    E-print Network

    Motta, Arthur T.

    associated with waterside corrosion on the component surface. The resulting uptake of hydrogen has long been-induced loss of ductility occurs when a surface crack initiates within a hydride rim or blister to the orientation of the hydride platelets such that KQ decreases by roughly a factor of three when a significant

  5. PREPRINT submitted to Journal of Physics B Electronic structure of the Magnesium hydride

    E-print Network

    Recanati, Catherine

    PREPRINT submitted to Journal of Physics B Electronic structure of the Magnesium hydride molecular: 31.15.AR,31.15.Ct,31.50.Be,31.50.Df #12; Electronic structure of the Magnesium hydride molecular ion 2 1. Introduction The reactivity of molecular systems in the gas phase at low temperature (as low

  6. The Mechanochemical Self-Propagating Reaction between Hexachlorobenzene and Calcium Hydride

    Microsoft Academic Search

    G. Mulas; S. Loiselle; L. Schiffini; G. Cocco

    1997-01-01

    We report on studies of the solid state reaction between hexachlorobenzene and calcium hydride carried out by high-energy ball milling. The transformation behavior depends on the intensity of the mechanical energy transferred to the reactants at the impact. At lower energy regimes, chemical conversions increase gradually as a function of the milling time and a large excess of calcium hydride

  7. Recent Advance of Hydride Generation–Analytical Atomic Spectrometry: Part I—Technique Development

    Microsoft Academic Search

    Zhou Long; Yamin Luo; Chengbin Zheng; Pengchi Deng; Xiandeng Hou

    2012-01-01

    Hydride generation is the most popular and widely used chemical vapor generation technique and is interesting to analytical chemists as an effective sample introduction method, especially for elemental determination and speciation analysis by analytical atomic spectrometry. The present review provides a literature survey on the hydride generation technique coupled to analytical atomic spectrometry during the past several years, covering the

  8. Recent Advance of Hydride Generation-Analytical Atomic Spectrometry: Part I-Technique Development

    Microsoft Academic Search

    Zhou Long; Yamin Luo; Chengbin Zheng; Pengchi Deng; Xiandeng Hou

    2012-01-01

    Hydride generation is the most popular and widely used chemical vapor generation, which is always interesting to analytical chemists as an effective sample introduction method, especially for elemental determination and speciation analysis by analytical atomic spectrometry. The present review provides a literature survey on the hydride generation technique coupled to analytical atomic spectrometry during the past several years, covering the

  9. Hydrogenation of CeNi: hydride formation, structure and magnetic J.-L. Bobet b*

    E-print Network

    Paris-Sud XI, Université de

    during hydriding. A survey of the crystal structures of RExT intermetallics where RE is a rare earthHydrogenation of CeNi: hydride formation, structure and magnetic properties J.-L. Bobet b* , E ______________________________________________________________________ Abstract The hydrogenation at different temperatures and hydrogen pressures of the binary intermetallic

  10. Reduction of carbon monoxide by a tetrakis(aryloxide)diniobium complex having four bridging hydrides.

    PubMed

    Kurogi, Takashi; Ishida, Yutaka; Hatanaka, Tsubasa; Kawaguchi, Hiroyuki

    2013-06-01

    The use of a sterically demanding aryloxide ligand allows us to isolate a tetrakis(aryloxide)diniobium complex bridged by four hydride ligands. This hydride aryloxide undergoes reduction of CO via hydrogenation and deoxygenation, resulting in formation of a methylidene species. Further carbonylation gives a vinylidene complex. PMID:23235738

  11. A microcalorimetric investigation of the thermodynamics and kinetics of hydriding-dehydriding reactions

    Microsoft Academic Search

    Wenlin Zhang; M. P. Sridhar Kumar; Arnaldo Visintin; Supramaniam Srinivasan; Harry J. Ploehn

    1996-01-01

    A microcalorimetric technique was used to study the thermodynamics and kinetics of the hydriding-dehydriding reactions of some AB5-type alloys. The effects of Ce, Co and Sn substitution were analyzed. Co and Sn substitution increase the stability of the hydride state, while Ce substitution has the opposite effect. These observations are rationalized on the basis of the rule of reversed stability

  12. Complex transition metal hydrides: linear correlation of countercation electronegativity versus T-D bond lengths.

    PubMed

    Humphries, T D; Sheppard, D A; Buckley, C E

    2015-06-30

    For homoleptic 18-electron complex hydrides, an inverse linear correlation has been established between the T-deuterium bond length (T = Fe, Co, Ni) and the average electronegativity of the metal countercations. This relationship can be further employed towards aiding structural solutions and predicting physical properties of novel complex transition metal hydrides. PMID:26077621

  13. Hydride-related degradation of spent-fuel cladding under repository conditions

    SciTech Connect

    Chung, H. M.

    2000-04-03

    This report summarizes results of an analysis of hydride-related degradation of commercial spent-nuclear-fuel cladding under repository conditions. Based on applicable laboratory data on critical stress intensity obtained under isothermal conditions, occurrence of delayed hydride cracking from the inner-diameter side of cladding is concluded to be extremely unlikely. The key process for potential initiation of delayed hydride cracking at the outer-diameter side is long-term microstructural evolution near the localized regions of concentrated hydrides, i.e., nucleation, growth, and cracking of hydride blisters. Such locally concentrated hydrides are, however, limited to some high-burnup cladding only, and the potential for crack initiation and propagation at the outer-diameter side is expected to be insignificant for most spent fuels. Some degree of hydride reorientation could occur in high-burnup spent-fuel cladding. However, even if hydride reorientation occurs, accompanying stress-rupture failure in spent-fuel cladding is unlikely to occur.

  14. An anisotropic Gurson type model to represent the ductile rupture of hydrided Zircaloy4 sheets

    Microsoft Academic Search

    M. Grange; J. Besson; E. Andrieu

    2000-01-01

    The aim of this work is to model the ductile fracture of Zircaloy-4 sheets containing various amount of embrittling hydride precipitates. The proposed model is based on the Gurson–Tvergaard–Needleman model which is extended to take into account plastic anisotropy and viscoplasticity. The mechanical behavior is identified by conducting tensile tests and the damage nucleation rate (hydride cracking) is measured using

  15. Performance improvement analysis of boiling water reactors by incorporation of hydride fuel

    Microsoft Academic Search

    Wang Kan; Greenspan Ehud

    2004-01-01

    The feasibility of improving the neutronic characteristics of boiling water reactors (BWR) by using U–Zr hydride fuel is studied. Several modified BWR fuel assembly designs are considered. These include designs in which hydride fuel rods replace water rods only, replace water rods and a fraction of the oxide fuel rods, replace oxide fuel in the upper half of all the

  16. The initiation of delayed hydride cracking in zirconium-2.5 niobium

    Microsoft Academic Search

    Derong Yan

    1999-01-01

    This thesis contains two parts of work that study the initiation of the delayed hydride cracking (DHC) in zirconium alloys in different aspects. The first part is a theoretical work in which the effect of stress on the hydride precipitation solvus in zirconium, is studied from the view point of thermodynamics. The material equilibrium of a closed thermodynamic system which

  17. Relativity and the mercury battery.

    PubMed

    Zaleski-Ejgierd, Patryk; Pyykkö, Pekka

    2011-10-01

    Comparative, fully relativistic (FR), scalar relativistic (SR) and non-relativistic (NR) DFT calculations attribute about 30% of the mercury-battery voltage to relativity. The obtained percentage is smaller than for the lead-acid battery, but not negligible. PMID:21750825

  18. PERCEPTION OF MERCURY RISK INFORMATION

    EPA Science Inventory

    Approximately 8% of American women have blood Mercury levels exceeding the EPA reference dose (a dose below which symptoms would be unlikely). The children of these women are at risk of neurological deficits (lower IQ scores) primarily because of the mother's consumption of conta...

  19. Venus and Mercury as Planets

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described.

  20. Catalytic regeneration of mercury sorbents.

    PubMed

    Bentley, Mark; Fan, Maohong; Dutcher, Bryce; Tang, Mingchen; Argyle, Morris D; Russell, Armistead G; Zhang, Yulong; Sharma, M P; Swapp, Susan M

    2013-11-15

    Traditionally, mercury sorbents are disposed of in landfills, which may lead to contamination of soil and groundwater. In this work, the regeneration of activated carbon (AC) as a mercury sorbent was investigated. The decomposition of HgCl2 on the surface of pure AC was studied, as well as sorbent which has been treated with FeCl3 or NaCl. In all cases, the sorbent is found to be structurally stable through a single regeneration, which is verified through BET, XRD, and XPS analysis. The desorption of mercury from the sorbent is found to follow Henry's law. Additionally, a kinetic analysis suggests that although the presence of activated carbon lowers the energy requirement for the desorption of mercury, it significantly decreases the rate by decreasing the concentration of the HgCl2. FeCl3 and NaCl both promoted the decomposition of HgCl2, but FeCl3 did so more significantly, increasing the rate constants by a factor of 10 and decreasing the activation energy for the decomposition of HgCl2 by 14% to 40%. PMID:24121636

  1. Getting metal-hydrides to do what you want them to

    SciTech Connect

    Gruen, D.M.

    1981-01-01

    With the discovery of AB/sub 5/ compounds, intermetallic hydrides with unusual properties began to be developed (H dissociation pressures of one to several atmospheres, extremely rapid and reversible adsorption/desorption very large amounts of H adsorbed). This paper reviews the factors that must be controlled in order to modify these hydrides to make them useful. The system LaNi/sub 5/ + H/sub 2/ is used as example. Use of AB/sub 5/ hydrides to construct a chemical heat pumps is discussed. Results of a systematic study substituting Al for Ni are reported; the HYCSOS pump is described briefly. Use of hydrides as hydrogen getters (substituted ZrV/sub 2/) is also discussed. Finally, possible developments in intermetallic hydride research in the 1980's and the hydrogen economy are discussed. 10 figures. (DLC)

  2. Study on Hydride Reorientation in Zry-2 Fuel Claddings during Interim Dry Storage

    SciTech Connect

    Sakamoto, K. [Global Nuclear Fuel - Japan Co., Ltd. (GNF-J), 2163, Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1313 (Japan); Matsuoka, H. [Global Nuclear Fuel - Japan Co., Ltd. (GNF-J), 3-1, Uchikawa 2-chome, Yokosuka-shi, Kanagawa 239-0836 (Japan); Takagi, A. [Tokyo Electric Power Co., Ltd. (TEPCO), 1-3 Uchisaiwai-cho, 1-chome, Chiyoda-ku, Tokyo 100-8560 (Japan); Kashibe, S. [Nippon Nuclear Fuel Development Co., Ltd. (NFD), 2163, Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1313 (Japan)

    2007-07-01

    The hydride reorientation during the interim dry storage was examined by hydride reorientation test using unirradiated recrystallized Zry-2 fuel claddings (Zr-lined). In the case of high hydrogen concentration (above 200 ppm), no measurable hydride reorientation was observed under the condition examined. On the other hand, for low hydrogen concentration (30 - 80 ppm), a significant hydride reorientation was observed above 618 K. The effects of thermal cycling and cooling rate were also examined. The mechanical property of the hydride-reoriented specimens was evaluated at room temperature by the ring-tensile test, which showed no degradation of hoop strength and ductility when temperature and hoop stress were not greater than 573 K and 70 MPa, even if the effects of cooling rate and thermal cycling were taken into account. (authors)

  3. A mechanical-force-driven physical vapour deposition approach to fabricating complex hydride nanostructures.

    PubMed

    Pang, Yuepeng; Liu, Yongfeng; Gao, Mingxia; Ouyang, Liuzhang; Liu, Jiangwen; Wang, Hui; Zhu, Min; Pan, Hongge

    2014-01-01

    Nanoscale hydrides desorb and absorb hydrogen at faster rates and lower temperatures than bulk hydrides because of their high surface areas, abundant grain boundaries and short diffusion distances. No current methods exist for the direct fabrication of nanoscale complex hydrides (for example, alanates, borohydrides) with unique morphologies because of their extremely high reducibility, relatively low thermodynamic stability and complicated elemental composition. Here, we demonstrate a mechanical-force-driven physical vapour deposition procedure for preparing nanoscale complex hydrides without scaffolds or supports. Magnesium alanate nanorods measuring 20-40?nm in diameter and lithium borohydride nanobelts measuring 10-40?nm in width are successfully synthesised on the basis of the one-dimensional structure of the corresponding organic coordination polymers. The dehydrogenation kinetics of the magnesium alanate nanorods are improved, and the nanorod morphology persists through the dehydrogenation-hydrogenation process. Our findings may facilitate the fabrication of such hydrides with improved hydrogen storage properties for practical applications. PMID:24663074

  4. Hydride-phase formation and its influence on fatigue crack propagationbehavior in a Zircaloy-4 alloy

    SciTech Connect

    Garlea, Elena [University of Tennessee, Knoxville (UTK); Choo, H. [University of Tennessee, Knoxville (UTK); Wang, G Y [University of Tennessee, Knoxville (UTK); Liaw, Peter K [University of Tennessee, Knoxville (UTK); Clausen, B [Los Alamos National Laboratory (LANL); Brown, D. W. [Los Alamos National Laboratory (LANL); Park, Jae-Sung [University of Tennessee, Knoxville (UTK); Rack, P. D. [University of Tennessee, Knoxville (UTK); Kenik, Edward A [ORNL

    2010-01-01

    The hydride-phase formation and its influence on the fatigue behavior of a Zircaloy-4 alloy charged with hydrogen gas are investigated. First, the microstructure and fatigue crack propagation rate of the alloy in the as-received condition are studied. Second, the formation and homogeneous distribution of delta zirconium hydride ( -ZrH2) in the bulk, and its effect on the fatigue crack propagation rate are presented. The results show that in the presence of hydrides the zirconium alloy exhibits reduced toughness and enhanced crack growth rates. Finally, the influence of a pre-existing fatigue crack in the specimen and the subsequent hydride formation were investigated. The residual lattice strain profile around the fatigue crack tip was measured using neutron diffraction. The combined effects of residual strains and hydride precipitation on the fatigue behavior are discussed.

  5. Strategies for the improvement of the hydrogen storage properties of metal hydride materials.

    PubMed

    Wu, Hui

    2008-10-24

    Metal hydrides are an important family of materials that can potentially be used for safe, efficient and reversible on-board hydrogen storage. Light-weight metal hydrides in particular have attracted intense interest due to their high hydrogen density. However, most of these hydrides have rather slow absorption kinetics, relatively high thermal stability, and/or problems with the reversibility of hydrogen absorption/desorption cycling. This paper discusses a number of different approaches for the improvement of the hydrogen storage properties of these materials, with emphasis on recent research on tuning the ionic mobility in mixed hydrides. This concept opens a promising pathway to accelerate hydrogenation kinetics, reduce the activation energy for hydrogen release, and minimize deleterious possible by-products often associated with complex hydride systems. PMID:18821548

  6. The Plasma Environment at Mercury

    NASA Technical Reports Server (NTRS)

    Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos; Sprague, Anne L.; McNutt, Ralph L., Jr.

    2011-01-01

    Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

  7. Environmental mercury and its toxic effects.

    PubMed

    Rice, Kevin M; Walker, Ernest M; Wu, Miaozong; Gillette, Chris; Blough, Eric R

    2014-03-01

    Mercury exists naturally and as a man-made contaminant. The release of processed mercury can lead to a progressive increase in the amount of atmospheric mercury, which enters the atmospheric-soil-water distribution cycles where it can remain in circulation for years. Mercury poisoning is the result of exposure to mercury or mercury compounds resulting in various toxic effects depend on its chemical form and route of exposure. The major route of human exposure to methylmercury (MeHg) is largely through eating contaminated fish, seafood, and wildlife which have been exposed to mercury through ingestion of contaminated lower organisms. MeHg toxicity is associated with nervous system damage in adults and impaired neurological development in infants and children. Ingested mercury may undergo bioaccumulation leading to progressive increases in body burdens. This review addresses the systemic pathophysiology of individual organ systems associated with mercury poisoning. Mercury has profound cellular, cardiovascular, hematological, pulmonary, renal, immunological, neurological, endocrine, reproductive, and embryonic toxicological effects. PMID:24744824

  8. Mercury emissions from municipal solid waste combustors

    SciTech Connect

    Not Available

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  9. Mercury volatilization from salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Smith, Lora M.; Reinfelder, John R.

    2009-06-01

    In situ volatilization fluxes of gaseous elemental mercury, Hg(0), were estimated for tidally exposed salt marsh sediments in the summer at the urban/industrial Secaucus High School Marsh, New Jersey Meadowlands (Secaucus, New Jersey) and in the early autumn at a regional background site in the Great Bay estuary (Tuckerton, New Jersey). Estimated daytime sediment-air mercury volatilization fluxes at the Secaucus High School Marsh ranged from -375 to +677 ng m-2 h-1 and were positive (land to air flux) in 16 out of 20 measurement events. At the Great Bay estuary, mercury fluxes measured continuously over a 48-h period ranged from -34 to +81 ng m-2 h-1 and were positive during the day and negative at night. At both sites, mercury volatilization fluxes peaked at midday, and cumulative mercury fluxes exhibited strong positive correlations with cumulative solar radiation (r2 = 0.97, p < 0.01) consistent with a light-driven mercury volatilization efficiency of about 15 ng Hg mol PAR-1 or about 0.06 ng Hg kJ-1. No significant correlations were found between mercury fluxes and wind speed, air temperature, or tide height at either site. Thus despite a tenfold difference in sediment mercury concentration, photochemistry appears to be the dominant factor controlling mercury volatilization from these salt marsh sediments. The average mercury volatilization flux estimated for the Great Bay salt marsh in this study (17 ng m-2 h-1) compares well with other micrometeorological mercury fluxes for nonpoint source contaminated salt marsh and forest soils (8-18 ng m-2 h-1) and is more than 10 times higher than the average mercury emission flux from land (˜1 ng m-2 h-1). Annual mercury emissions from salt marsh wetlands may be comparable to individual industrial emissions sources in coastal states of the eastern United States.

  10. Mercury's Sodium Exosphere: Magnetospheric Ion recycling

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Delcourt, D.; Johnson, R. E.; Liu, M.

    2003-05-01

    The temporal and spatial variability in 3D of Mercury's neutral sodium exosphere and its correlation with the sodium density in Mercury's surface was described for Mercury's motion around the Sun (Leblanc and Johnson 2003). Four processes for ejection of sodium were taken into account: thermal and photon stimulated desorptions, solar wind sputtering and micro-meteoroid vaporization. A model of ion circulation in Mercury's magnetosphere developed by Delcourt et al. (2002; 2003) is used here to follow the newly ionized particles produced by this model of Mercury's neutral sodium exosphere. The motion of Na+ and Na around Mercury are dynamically coupled. The contribution to sputtering and the local increase in the Na density in Mercury's surface by the reimpacting ions is discussed. Magnetospheric ion sputtering does not contribute significantly to the total amount of Na atoms ejected into Mercury's exosphere because of the rather small flux of magnetospheric ion reimpacting Mercury's surface. However magnetospheric ion reimplantation in Mercury's surface is sufficiently concentrated inside narrow latitude bands to enhance significantly the local concentration of sodium in Mercury's surface. As a consequence, certain peaks in Mercury's exospheric sodium emission observed at high latitudes could be due to the release on the dayside of these magnetospheric sodium ions reimplanted into Mercury's nightside surface at high latitudes (as previously suggested by Sprague 1992 and Ip 1993). Sprague, J. Geophys. Res., 97, 18257, 1992; Ip, Astrophys. J., 418, 451, 1993; Leblanc and Johnson, Icarus, In press 2003; Delcourt et al. Geophys. Let. Res., 29, 2002; Delcourt et al., Ann. Geophysicae, In press 2003.

  11. Materials for Hydrogen Storage: From Complex Hydrides to Functionalized Nanostructures

    NASA Astrophysics Data System (ADS)

    Das, G. P.

    2011-07-01

    The world wide effort for a transition to renewable and clean (i.e. carbon-free) form of energy has resulted in an upsurge of interest in harnessing and utilizing Hydrogen. Apart from being the most abundant element in the universe, hydrogen offers many advantages over other fuels: it is non-toxic, clean to use, and packs more energy per mass than any other fuel. Hydrogen energy production, storage and distribution constitute a multi-disciplinary area of research. Coming to the material issues for solid state storage of hydrogen, the most desirable criteria are high storage capacity, satisfactory kinetics, and optimal thermodynamics. Complex hydrides involving light metals, such as Alanates, Imides, Borates, Amidoboranes etc. show impressive gravimetric efficiencies, although the hydrogen desorption temperatures turn out to be rather high. Apart from complex hydrides, there are other kinds of novel materials that have been investigated, e.g. carbon based materials activated with nano-catalysts, clathrate hydrates, metal-organic complexes, and more recently nanostructured cages viz. fullerenes and nanotubes decorated with simple or transition metals that serve to attract hydrogen in molecular form. In this talk, after giving a broad overview on hydrogen economy, I shall focus on first-principles design of materials for hydrogen storage, from complex hydrides to various kinds of functinalized nanostructures, and discuss the recent results obtained in our laboratory [1-6]. Some outstanding issues and challenges, like how to circumvent the problem of metal clustering on surface, or how to bring down the hydrogen desorption temperature etc. will be discussed.

  12. Mathematical modeling of the nickel/metal hydride battery system

    SciTech Connect

    Paxton, B K [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

    1995-09-01

    A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investigation due to the wealth of information available in the literature on this compound. The model results are compared to experiments found in the literature. Fundamental analyses as well as engineering optimizations are performed from the results of the battery model. In order to examine diffusion limitations in the nickel oxide electrode, a ``pseudo 2-D model`` is developed. This model allows for the theoretical examination of the effects of a diffusion coefficient that is a function of the state of charge of the active material. It is found using present data from the literature that diffusion in the solid phase is usually not an important limitation in the nickel oxide electrode. This finding is contrary to the conclusions reached by other authors. Although diffusion in the nickel oxide active material is treated rigorously with the pseudo 2-D model, a general methodology is presented for determining the best constant diffusion coefficient to use in a standard one-dimensional battery model. The diffusion coefficients determined by this method are shown to be able to partially capture the behavior that results from a diffusion coefficient that varies with the state of charge of the active material.

  13. Magnesium hydrides and the dearomatisation of pyridine and quinoline derivatives.

    PubMed

    Hill, Michael S; Kociok-Köhn, Gabriele; MacDougall, Dugald J; Mahon, Mary F; Weetman, Catherine

    2011-12-14

    Reactions of the ?-diketiminato n-butyl magnesium complex, [HC{(Me)CN(2,6-(i)Pr(2)C(6)H(3))}(2)Mg(n)Bu], with a range of substituted pyridines and fused-ring quinolines in the presence of PhSiH(3) has been found to result in dearomatisation of the N-heterocyclic compounds. This reaction is proposed to occur through the formation of an unobserved N-heterocycle-coordinated magnesium hydride and subsequent hydride transfer via the C2-position of the heterocycle prior to hydride transfer to the C4-position and formation of thermodynamically-favoured magnesium 1,4-dihydropyridides. This reaction is kinetically suppressed for 2,6-dimethylpyridine while the kinetic product, the 1,2-dihydropyridide derivative, was isolated through reaction with 4-methylpyridine (4-methylpyridine), in which case the formation of the 1,4-dihyropyridide is prevented by the presence of the 4-methyl substituent. X-ray structures of the products of these reactions with 4-methylpyridine, 3,5-dimethylpyridine and iso-quinoline comprise a pseudo-tetrahedral magnesium centre while the regiochemistry of the particular dearomatisation reaction is determined by the substitution pattern of the N-heterocycle under observation. The compounds are all air-sensitive and exposure of the magnesium derivatives of dearomatised pyridine and 4-dimethylaminopyridine (DMAP) to air resulted in ligand rearomatisation and the formation of dimeric ?(2)-?(2)-?(2)-peroxomagnesium compounds which have also been subject to analysis by single crystal X-ray diffraction analysis. An unsuccessful extension of this chemistry to N-heterocycle hydrosilylation is suggested to be a consequence of the low basicity of the silane reagent in comparison to the pyridine substrates which effectively impedes any further interaction with the magnesium centres. PMID:21986998

  14. Optical properties of metal-hydride switchable films

    NASA Astrophysics Data System (ADS)

    Griessen, Ronald

    2001-03-01

    In 1996 we discovered that yttrium-, lanthanum-, and rare-earth-hydride (REHx) films [1] protected by a thin palladium layer, exhibit spectacular changes in their optical properties when the hydrogen concentration x is increased from 2 to 3. For example, a 500 nm thick YH2 film is metallic and shiny while YH3 is yellowish and transparent. The transition is reversible, fast [2, 3], and can simply be induced by adding or removing hydrogen from the gas phase, an electrolyte or from an H containing liquid. The optical switching that occurs near the metal-insulator transition of these hydrides is remarkably robust as it is not affected by structural or compositional disorder. It occurs in polycrystalline and epitaxial films, in alloys with cubic or hexagonal crystal structures,and deuterides [4] switch as well as hydrides. At small length scales epitaxial YHx films exhibit surprising structural properties which open the way to pixel-by-pixel optical switching [5]. Colour-neutral switchable mirrors based on RE-Mg alloys [6] can be used in all-solid-state switchable devices. Newest results for Rare-Earth free switchable mirrors will be presented. [1] J. N. Huiberts, R. Griessen, J. H. Rector, R. J. Wijngaarden, J. P. Dekker, D. G. de Groot and N. J. Koeman, Nature 380 (1996) 231; [2] S. J. van der Molen, J. W. J. Kerssemakers, J. H. Rector, N. J. Koeman, B. Dam, R. Griessen, J. Appl. Phys. 86 (1999) 6107; [3] F. J. A. den Broeder, S. J. van der Molen, et al., Nature 394 (1998)656; [4] A. T. M. van Gogh, E. S. Kooij, R. Griessen, Phys. Rev. Lett. 83 (1999) 4614; [5] J. W. J. Kerssemakers, S. J. van der Molen and R. Griessen, Nature 406 (2000) 489; [6] P. van der Sluis, M. Ouwerkerk and P. A. Duine, Appl. Phys. Lett. 70 (1997) 3356.

  15. RECOVERY OF MERCURY FROM CONTAMINATED LIQUID WASTES

    SciTech Connect

    Robin M. Stewart

    1999-09-29

    Mercury was widely used in U.S. Department of Energy (DOE) weapons facilities, resulting in a broad range of mercury-contaminated wastes and wastewaters. Some of the mercury contamination has escaped to the local environment, particularly at the Y-12 Plant in Oak Ridge, Tennessee, where approximately 330 metric tons of mercury were discharged to the environment between 1953 and 1963 (TN & Associates, 1998). Effective removal of mercury contamination from water is a complex and difficult problem. In particular, mercury treatment of natural waters is difficult because of the low regulatory standards. For example, the Environmental Protection Agency has established a national ambient water quality standard of 12 parts-per-trillion (ppt), whereas the standard is 1.8 ppt in the Great Lakes Region. In addition, mercury in the environment is typically present in several different forms, but sorption processes are rarely effective with more than one or two of these forms. To meet the low regulatory discharge limits, an effective sorption process must be able to address all forms of mercury present in the water. One approach is to apply different sorbents in series depending on the mercury speciation and the regulatory discharge limits. ADA Technologies, Inc. has developed four new sorbents to address the variety of mercury species present in industrial discharges and natural waters. Three of these sorbents have been field tested on contaminated creek water at the Y-12 Plant. Two of these sorbents have been successfully demonstrated very high removal efficiencies for soluble mercury species, reducing mercury concentrations at the outlet of a pilot-scale system to less than 12 ppt for as long as six months. The other sorbent tested at the Y-12 Plant targeted colloidal mercury not removed by standard sorption or filtration processes. At the Y-12 Plant, colloidal mercury appears to be associated with iron, so a sorbent that removes mercury-iron complexes in the presence of a magnetic field was evaluated. Field results indicated good removal of this mercury fraction from the Y-12 waters. In addition, this sorbent is easily regenerated by simply removing the magnetic field and flushing the columns with water. The fourth sorbent is still undergoing laboratory development, but results to date indicate exceptionally high mercury sorption capacity. The sorbent is capable of removing all forms of mercury typically present in natural and industrial waters, including Hg{sup 2+}, elemental mercury, methyl mercury, and colloidal mercury. The process possesses very fast kinetics, which allows for higher flow rates and smaller treatment units. These sorbent technologies, used in tandem or individually depending on the treatment needs, can provide DOE sites with a cost-effective method for reducing mercury concentrations to very low levels mandated by the regulatory community. In addition, the technologies do not generate significant amounts of secondary wastes for disposal. Furthermore, the need for improved water treatment technologies is not unique to the DOE. The new, stringent requirements on mercury concentrations impact other government agencies as well as the private sector. Some of the private-sector industries needing improved methods for removing mercury from water include mining, chloralkali production, chemical processing, and medical waste treatment. The next logical step is to deploy one or more of these sorbents at a contaminated DOE site or at a commercial facility needing improved mercury treatment technologies. A full-scale deployment is planned in fiscal year 2000.

  16. Structure of hydrides based on V-Cr alloys

    NASA Astrophysics Data System (ADS)

    Lushnikov, S. A.; Verbetskii, V. N.; Somenkov, V. A.; Glazkov, V. P.

    2014-11-01

    The structure of deuterides based on V0.9Cr0.1 and V0.5Cr0.5 alloys has been investigated by neutron diffraction at room and low (77 K) temperatures. It is found that V0.9Cr0.1D2.0 deuteride has a CaF2 ( Fm3 m) crystal structure, which corresponds to vanadium dihydride. V0.5Cr0.5D0.7 deuteride has a NiAs ( P6/3 mmc) structure type, similar to chromium hydride.

  17. Electrophilicity of quinones and its relationship with hydride affinity

    NASA Astrophysics Data System (ADS)

    Campodónico, Paola R.; Aizman, Arie; Contreras, Renato

    2009-03-01

    In this Letter we show that the electrophilicity index assesses well the hydride affinity (HA) order of quinones established for a limited number of cases experimentally observed. Further comparisons with predicted HA values for a larger data base suggest that both the electrophilicity index and HA are tightly related quantities. Furthermore, electrophilic activation/deactivation patterns induced by electron-withdrawing and electron-donating groups may be consistently accounted for by the model. These results open the possibility of predicting HA for quinones not evaluated experimentally up to date.

  18. Bipolar Nickel-Metal Hydride Battery Development Project

    NASA Technical Reports Server (NTRS)

    Cole, John H.

    1999-01-01

    This paper reviews the development of the Electro Energy, Inc.'s bipolar nickel metal hydride battery. The advantages of the design are that each cell is individually sealed, and that there are no external cell terminals, no electrode current collectors, it is compatible with plastic bonded electrodes, adaptable to heat transfer fins, scalable to large area, capacity and high voltage. The design will allow for automated flexible manufacturing, improved energy and power density and lower cost. The development and testing of the battery's component are described. Graphic presentation of the results of many of the tests are included.

  19. Stress analysis of hydride bed vessels used for tritium storage

    SciTech Connect

    McKillip, S.T.; Bannister, C.E.; Clark, E.A.

    1991-12-31

    A prototype hydride storage bed, using LaNi{sub 4.25}Al{sub 0.75} as the storage material, was fitted with strain gages to measure strains occurring in the stainless steel bed vessel caused by expansion of the storage powder upon uptake of hydrogen. The strain remained low in the bed as hydrogen was added, up to a bed loading of about 0.5 hydrogen to metal atom ratio (H/M). The strain then increased with increasing hydrogen loading ({approximately} 0.8 H/M). Different locations exhibited greatly different levels of maximum strain. In no case was the design stress of the vessel exceeded.

  20. Stress analysis of hydride bed vessels used for tritium storage

    SciTech Connect

    McKillip, S.T.; Bannister, C.E.; Clark, E.A.

    1991-01-01

    A prototype hydride storage bed, using LaNi{sub 4.25}Al{sub 0.75} as the storage material, was fitted with strain gages to measure strains occurring in the stainless steel bed vessel caused by expansion of the storage powder upon uptake of hydrogen. The strain remained low in the bed as hydrogen was added, up to a bed loading of about 0.5 hydrogen to metal atom ratio (H/M). The strain then increased with increasing hydrogen loading ({approximately} 0.8 H/M). Different locations exhibited greatly different levels of maximum strain. In no case was the design stress of the vessel exceeded.

  1. Electrochemical process and production of novel complex hydrides

    DOEpatents

    Zidan, Ragaiy

    2013-06-25

    A process of using an electrochemical cell to generate aluminum hydride (AlH.sub.3) is provided. The electrolytic cell uses a polar solvent to solubilize NaAlH.sub.4. The resulting electrochemical process results in the formation of AlH.sub.3. The AlH.sub.3 can be recovered and used as a source of hydrogen for the automotive industry. The resulting spent aluminum can be regenerated into NaAlH.sub.4 as part of a closed loop process of AlH.sub.3 generation.

  2. Modeling of Gallium Nitride Hydride Vapor Phase Epitaxy

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    A reactor model for the hydride vapor phase epitaxy of GaN is presented. The governing flow, energy, and species conservation equations are solved in two dimensions to examine the growth characteristics as a function of process variables and reactor geometry. The growth rate varies with GaCl composition but independent of NH3 and H2 flow rates. A change in carrier gas for Ga source from H2 to N2 affects the growth rate and uniformity for a fixed reactor configuration. The model predictions are in general agreement with observed experimental behavior.

  3. Chemical Hydrides for Hydrogen Storage in Fuel Cell Applications

    SciTech Connect

    Devarakonda, Maruthi N.; Brooks, Kriston P.; Ronnebro, Ewa; Rassat, Scot D.; Holladay, Jamelyn D.

    2012-04-16

    Due to its high hydrogen storage capacity (up to 19.6% by weight for the release of 2.5 molar equivalents of hydrogen gas) and its stability under typical ambient conditions, ammonia borane (AB) is a promising material for chemical hydrogen storage for fuel cell applications in transportation sector. Several systems models for chemical hydride materials such as solid AB, liquid AB and alane were developed and evaluated at PNNL to determine an optimal configuration that would meet the 2010 and future DOE targets for hydrogen storage. This paper presents an overview of those systems models and discusses the simulation results for various transient drive cycle scenarios.

  4. Regional Scale Photochemical Model Evaluation of Total Mercury Wet Deposition and Speciated Ambient Mercury

    EPA Science Inventory

    Methylmercury is a known neurotoxin with deleterious health effects on humans and wildlife. Atmospheric deposition is the largest source of mercury loading to most terrestrial and aquatic ecosystems. Regional scale air quality models are needed to quantify mercury deposition resu...

  5. CURRENT METHODS AND RESEARCH STRATEGIES FOR MODELING ATMOSPHERIC MERCURY

    EPA Science Inventory

    The atmospheric pathway of the global mercury cycle is known to be the primary source of mercury contamination to most threatened aquatic ecosystems. Current efforts toward numerical modeling of atmospheric mercury are hindered by an incomplete understanding of emissions, atmosp...

  6. Mercury Dust Monitor for the BepiColombo MMO

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Shibata, H.; Nogami, K.; Fujii, M.; Miyachi, T.; Ohashi, H.; Sasaki, S.; Iwai, T.; Hattori, M.; Kimura, H.; Hirai, T.; Takechi, S.; Yano, H.; Hasegawa, S.; Srama, R.; Grün, E.

    2012-10-01

    Mercury Dust Monitor (MDM) onboard the Mercury Magnetosphere Orbiter (MMO) will observe dust particles in orbit around Mercury during 1 year as nominal operation. In this paper, we report an overview of our instrument onboard the Bepi-Colombo MMO.

  7. Mercury's Mg Exosphere from MESSENGER data

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R. M.; McClintock, W. E.; Vervack, R. J., Jr.; Merkel, A. W.; Burger, M. H.; Cassidy, T. A.; slavin, J. A.; Sprague, A. L.; Solomon, S. S.

    2012-09-01

    The discovery measurements of Mercury's exospheric magnesium, obtained by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) probe during its second Mercury flyby [1], revealed a distribution with altitude that could not be attributed to a single ejection process from the regolith [2, 3]. Rather, the observed mix of cooler and hot components implied that multiple source mechanisms were at play, none of which dominated [2, 3]. Source processes considered included micrometeoroid impact vaporization, molecular photo- dissociation, and solar wind sputtering. MESSENGER entered orbit about Mercury on 18 March, 2011. Since then, the Ultraviolet and Visible Spectrometer (UVVS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. We present measurements with the UVVS of the magnesium distribution, obtained during the first six months of the primary orbital mission, to better constrain the source processes for this species.

  8. Explaining Mercury's peculiar magnetic field

    NASA Astrophysics Data System (ADS)

    Wicht, Johannes; Cao, Hao; Heyner, Daniel; Dietrich, Wieland; Christensen, Ulrich R.

    2014-05-01

    MESSENGER magnetometer data revealed that Mercury's magnetic field is not only particularly weak but also has a peculiar geometry. The MESSENGER team finds that the location of the magnetic equator always lies significantly north of the geographic equator, is largely independent of the distance to the planet, and also varies only weakly with longitude. The field is best described by an axial dipole that is offset to the north by about 20% of the planetary radius. In terms of classical Gauss coefficients, this translates into a low axial dipole component of g10= -190 nT but a relatively large axial quadrupole contribution that amounts to roughly 40% of this value. The axial octupole is also sizable while higher harmonic contributions are much weaker. Very remarkable is also the fact that the equatorial dipole contribution is very small, consistent with a dipole tilt below 0.8 degree, and this is also true for the other non-axisymmetic field contributions. We analyze several numerical dynamos concerning their capability of explaining Mercury's magnetic field. Classical schemes geared to model the geomagnetic field typically show a much weaker quadrupole component and thus a smaller offset. The onset only becomes larger when the dynamo operates in the multipolar regime at higher Rayleigh numbers. However, since the more complex dynamics generally promotes all higher multipole contributions the location of the magnetic equator varies strongly with longitude and distance to the planet. The situation improves when introducing a stably stratified outer layer in the dynamo region, representing either a rigid FeS layer or a sub-adiabatic core-mantle boundary heat flux. This layer filters out the higher harmonic contributions and the field not only becomes sufficiently weak but also assumes a Mercury like offset geometry during a few percent of the simulation time. To increase the likelihood for the offset configuration, the north-south symmetry must be permanently broken and we explore two scenarios. Increasing the heat flux through the northern hemisphere of the core-mantle boundary is an obvious choice but is not supported by current models for Mercury's mantle. We find that a combination of internal rather than bottom driving and an increased heat flux through the equatorial region of the core-mantle boundary also promotes the required symmetry breaking and results in very Mercury like fields. The reason is that the imposed heat flux pattern, though being equatorially symmetric, lowers the critical Rayleigh number for the onset of equatorially anti-symmetric convection modes. In both scenarios, a stably stratified layer or a feedback coupling to the magnetospheric field is required for lowering the field strength to Mercury-like values.

  9. Chemical Form Matters: Differential Accumulation of Mercury Following Inorganic and Organic Mercury Exposures in Zebrafish Larvae

    Microsoft Academic Search

    Malgorzata Korbas; Tracy C. MacDonald; Ingrid J. Pickering; Graham N. George; Patrick H. Krone

    2012-01-01

    Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury

  10. Evaluation of an Offline Method for the Analysis of Atmospheric Reactive Gaseous Mercury and Particulate Mercury

    Microsoft Academic Search

    Andrew P. Rutter; Katy L. Hanford; Jaime T. Zwers; Anthony L. Perillo-Nicholas; James J. Schauer; Mark L. Olson; Kostantinos Eleftheriadis; Eleftheria Katsivela; Donald Martello; Natalie Pekney; Richard Anderson; Cliff Davidson; Philip Hopke; Eugene Kim; William Christensen; Nolan Mangelson; Delbert Eatough; Saqib Mukhtar; Atilla Mutlu; Sergio Capareda; Calvin Parnell; Paul Scott; Deborah Proctor; Yinka Afon; David Ervin; Li Wang; Praveen Kolar; James Kastner; Brian Herner; Yifang Zhu; David Fung; Nola Kennedy; William Hinds; Arantzazu Eiguren-Fernandez; David Stieb; Richard Burnett; Marc Smith-Doiron; Orly Brion; Hwashin Shin; Vanita Economou; Rich Cook; Vlad Isakov; Jawad Touma; William Benjey; James Thurman; Ellen Kinnee; Darrell Ensley

    2008-01-01

    Reactive gaseous mercury (RGM) and particulate mercury (PHg) were collected in Milwaukee, WI, between April 2004 and May 2005, and in Riverside, CA, between July 25 and August 7, 2005 using sorbent and filter substrates. The substrates were analyzed for mercury by thermal desorption analysis (TDA) using a purpose-built instrument. Results from this offline-TDA method were compared with measurements using

  11. Biomarkers of Mercury Exposure at a Mercury Recycling Facility in Ukraine

    Microsoft Academic Search

    Herman Jones Gibb; Kostj Kozlov; Jessie Poulin Buckley; Jose Centeno; Vera Jurgenson; Allan Kolker; Kathryn Conko; Edward Landa; Boris Panov; Yuri Panov; Hanna Xu

    2008-01-01

    This study evaluates biomarkers of occupational mercury exposure among workers at a mercury recycling operation in Gorlovka, Ukraine. The 29 study participants were divided into three occupational categories for analysis: (1) those who worked in the mercury recycling operation (Group A, n = 8), (2) those who worked at the facility but not in the yard where the recycling was

  12. A low cost Mercury orbiter mission

    Microsoft Academic Search

    Kenneth J. Ely; Wallace T. Fowler; Byron D. Tapley

    1995-01-01

    Due to Mercury's small mass and position deep within the solar gravitational well, an orbiter mission poses difficult performance requirements (i.e. ?V, thermal extremes). However, Yen (JPL) showed that with extended trip times, substantial Mercury missions are feasible. Low cost, quick concept-to-launch, high quality, and reliability are balanced in constraining a small spacecraft mission to Mercury. The primary science objective

  13. Process for removing mercury from aqueous solutions

    DOEpatents

    Googin, J.M.; Napier, J.M.; Makarewicz, M.A.; Meredith, P.F.

    1985-03-04

    A process for removing mercury from water to a level not greater than two parts per billion wherein an anion exchange material that is insoluble in water is contacted first with a sulfide containing compound and second with a compound containing a bivalent metal ion forming an insoluble metal sulfide. To this treated exchange material is contacted water containing mercury. The water containing not more than two parts per billion of mercury is separated from the exchange material.

  14. Mercury Sodium Atmosphere, Magnetosphere and Solar Wind

    Microsoft Academic Search

    R. M. Killen; B. Giles; A. E. Potter; B. V. Jackson; J. Linker; Z. Mikic

    1999-01-01

    Earth-based observations of Mercury's sodium atmosphere have revealed large-scale spatial variations and rapid temporal variations (e.g. Potter and Morgan, Adv. Space Res. 19, 1571, 1997; Potter, A.E. et al., Planet. Space. Sci., In press, 1999). We show how the observed brightness variations may be related to the topology of Mercury's magnetosphere in response to solar wind variations at Mercury's orbit.

  15. Investigation of mercury speciation in lichens.

    PubMed

    Lupsina, V; Horvat, M; Jeran, Z; Stegnar, P

    1992-03-01

    Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points. PMID:1580418

  16. Mercury: Measuring and Managing the Risk

    Microsoft Academic Search

    Robert C. Harriss; Christoph Hohenemser

    1978-01-01

    The authors first review the history of acute mercury poisoning, esp. the 1950--1960s Minamata, Japan fishing village episode; the Ontario, Canada contaminated streams in the early 1970s; and the Iraq incident in 1971--1972 when some 500 people died after eating homemade bread made with wheat contaminated by a methyl mercury fungicide. Afterwards, the two principal pathways of mercury release from

  17. Dr. von Braun with Original Mercury Astronauts

    NASA Technical Reports Server (NTRS)

    1959-01-01

    Dr. Wernher von Braun, Director of the Army Ballistic Missile Agency's (ABMA) Development Operations Division, poses with the original Mercury astronauts in ABMA's Fabrication Laboratory during a 1959 visit. Inspecting Mercury-Redstone hardware are from left to right, Alan Shepard, Donald Deke Slayton, Virgil Gus Grissom, von Braun, Gordon Cooper, Wally Schirra, John Glenn, and Scott Carpenter. Project Mercury officially began October 7, 1958 as the United States' first manned space program.

  18. US mercury recyclers provide expanded process capabilities

    Microsoft Academic Search

    P. B. Queneau; L. A. Smith; M. D. Royer

    1994-01-01

    The article summarizes the treatment capabilities of U.S. plants recovering mercury from a variety of secondaries. There are six non-captive U.S. operations that accept various types of mercury-containing secondaries and wastes for mercury recovery, not including those firms specializing in processing spent lamps. Two of these operations, Adrow Chemical and D.F. Goldsmith Metal and Chemical, specialize in distillation of >

  19. Trends in mercury concentrations in New York State fish.

    PubMed

    Simonin, Howard A; Loukmas, Jefferey J; Skinner, Lawrence C; Roy, Karen M; Paul, Eric A

    2009-08-01

    Atmospheric emissions of mercury in the US are being reduced, but worldwide mercury emissions remain high. Mercury is also being removed from many consumer items. Changes over time in mercury concentrations in fish remain important to resource managers and the general public. There is hope that mercury concentrations in fish will decline, and the number of fish consumption advisories due to mercury will decrease. We compared mercury concentrations in yellow perch (Perca flavescens) from a group of Adirondack lakes with data collected 12-17 years earlier and found variable responses among lakes. We observed an average decline of 14% in yellow perch mercury concentrations over the past 15 years. PMID:19330274

  20. Absorption characteristics of elemental mercury in mercury chloride solutions.

    PubMed

    Ma, Yongpeng; Xu, Haomiao; Qu, Zan; Yan, Naiqiang; Wang, Wenhua

    2014-11-01

    Elemental mercury (Hg(0)) in flue gases can be efficiently captured by mercury chloride (HgCl2) solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg(0) absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl(-) to HgCl2 is 10:1, the Hg(0) removal efficiency is the highest. Among the main mercury chloride species, HgCl3(-) is the most efficient ion for Hg(0) removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg(0) absorption reactions in the aqueous phase were investigated computationally using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3(2-) and SO2, Hg(2+) reduction occurred and Hg(0) removal efficiency decreased. The reduced Hg(0) removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCl2 solution enhanced the Hg(0) removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4(2-) and NO3(-) did not affect Hg(0) removal by HgCl2. PMID:25458680

  1. Accumulation of mercury in the anterior pituitary of rats following oral or intraperitoneal administration of methyl mercury

    Microsoft Academic Search

    Bjarne Møller-Madsen; Ole Thorlacius-Ussing

    1986-01-01

    Summary  A sensitive histochemical technique has been used to visualize the ultrastructural localization of mercury in the anterior\\u000a pituitary of rats which have been exposed to methyl mercury. After administration of methyl mercury in the drinking water\\u000a (20 mg × 1?1 methyl mercury in distilled water) or intraperitoneally (daily dose 100 ug or 200 ug methyl mercury) intracellular accumulations\\u000a of mercury

  2. Comparison of pressurized sulfur hydride with conventional superconductors

    NASA Astrophysics Data System (ADS)

    Nicol, E. J.; Carbotte, J. P.

    2015-06-01

    A recent report that sulfur hydride under pressure is an electron-phonon superconductor with a Tc of 190 K has been met with much excitement although it is yet to be confirmed. Based on several electron-phonon spectral density functions already available from density functional theory, we find that the electron-phonon spectrum is near optimum for Tc with a particularly large value of its characteristic phonon energy ?ln which is due to the small hydrogen mass. We find that the thermodynamic universal BCS ratios are near those for Pb and Nb3Sn . We suggest that optical measurements could be a useful tool to establish the existence and nature of the superconductivity in this system. Conventional superconductors are in the impurity-dominated dirty limit. By contrast sulfur hydride will be in the clean limit because of its large energy gap scale. The ac optical conductivity will display distinct and separate signatures of the superconducting gap in the low-energy impurity-dominated range of the optical spectrum and additional phonon structures at higher energies where the clean limit applies.

  3. ACCEPTABILITY ENVELOPE FOR METAL HYDRIDE-BASED HYDROGEN STORAGE SYSTEMS

    SciTech Connect

    Hardy, B.; Corgnale, C.; Tamburello, D.; Garrison, S.; Anton, D.

    2011-07-18

    The design and evaluation of media based hydrogen storage systems requires the use of detailed numerical models and experimental studies, with significant amount of time and monetary investment. Thus a scoping tool, referred to as the Acceptability Envelope, was developed to screen preliminary candidate media and storage vessel designs, identifying the range of chemical, physical and geometrical parameters for the coupled media and storage vessel system that allow it to meet performance targets. The model which underpins the analysis allows simplifying the storage system, thus resulting in one input-one output scheme, by grouping of selected quantities. Two cases have been analyzed and results are presented here. In the first application the DOE technical targets (Year 2010, Year 2015 and Ultimate) are used to determine the range of parameters required for the metal hydride media and storage vessel. In the second case the most promising metal hydrides available are compared, highlighting the potential of storage systems, utilizing them, to achieve 40% of the 2010 DOE technical target. Results show that systems based on Li-Mg media have the best potential to attain these performance targets.

  4. Kinetic deuterium isotope effects on ligand migrations in metal hydrides

    SciTech Connect

    Bracker-Novak, J.; Hajela, S.; Lord, M.; Zhang, Minsheng; Rosenberg, E. (California State Univ., Northridge (USA)); Gobetto, R.; Milone, L.; Osella, D. (Universita di Torino (Italy))

    1990-05-01

    Variable-temperature (VT) {sup 1}H and {sup 13}C NMR studies of the complexes ({mu}-X){sub 2}Os{sub 3}(CO){sub 9}({mu}{sub 3}-{eta}{sup 2}-(CH{sub 3}CH{sub 2}){sub 2}C{sub 2}) (X = H or D) reveal that alkyne migration over the face of the cluster is directly linked to hydride migrations on the metal core as evidenced by a temperature-independent isotope effect (k{sub HH}/k{sub DD} = 1.7). In a related study of the VT {sup 13}C NMR of ({mu}-X){sub 2}M{sub 3}(CO){sub 9}({mu}{sub 3}-S) (X = H or D; M = Ru, Os) the observation of a k{sub HH}/k{sub DD} = 1.6 for both the osmium and ruthenium complexes demonstrates that the first stage of carbonyl averaging is brought about by hydride migration and not axial-radial exchange of carbonyl groups, a process that occurs only at higher temperatures. The mechanistic implications of these results are discussed in the context of the reactivity of metal clusters and the dynamic properties of the metal-hydrogen bond.

  5. Hydride formation in Ce(La)–Ni–Si ternary compounds

    Microsoft Academic Search

    S. A Lushnikov; S. N Klyamkin; A. V Morozkin; V. N Verbetsky

    1999-01-01

    Hydrogen interaction with R2Ni0.8Si1.2, R2NiSi, R2Ni1.2Si0.8 and R6Ni2Si3 (R=La, Ce) compounds were studied. The new hydride phases, namely, La2Ni0.8Si1.2H3.75, La2NiSiH3.9, La2Ni1.2Si0.8H4.4, Ce2Ni0.8Si1.2H3.7, Ce2NiSiH4.4, Ce2Ni1.2Si0.8H4.9, La6Ni2Si3H12 and Ce6Ni2Si3H10.9 have been synthesised and characterised by X-ray diffraction and thermodesorption methods. All hydrides retained the structure type of the starting compounds with pronounced anisotropic distortion of crystal lattice: the increase of the «a»

  6. Method of generating hydrogen-storing hydride complexes

    DOEpatents

    Srinivasan, Sesha S; Niemann, Michael U; Goswami, D. Yogi; Stefanakos, Elias K

    2013-05-14

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  7. Physics of Hydrogen Storage in Metal-Hydrides

    NASA Astrophysics Data System (ADS)

    Abdelfattah-Zidan, Ragaiy

    Physical aspects of the hydrogenation-dehydrogenation mechanisms of metal-metal hydride systems were examined. Experimental investigation was conducted for magnesium hydride as a case study. Theoretical analysis and computational study were carried out. The kinetics of hydrogenation-dehydrogenation of traditionally prepared Mg-MgH_2 and chemically synthesized Mg-MgH_2 were experimentally investigated. A detailed investigation was carried out to determine the reasons for the improved performance of a chemically synthesized Mg-MgH _2 previously reported by Bogdanovic and co-workers. A scanning electron microscope was used to examine the surface morphology of the samples. The surface of chemically prepared samples appeared to be covered with micro-spheroidal beads ranging in radius between 0.5 ?m and 0.05 ?m formed in a fractal-like configuration. Theoretical analysis indicated that the unusual surface structure of the chemically prepared samples could be responsible for the rapid uptake and release of hydrogen. The uptake and release enhancement is believed to be partially due to the substantial increase in the surface area and partially due fast diffusion into the smaller particles. The effect of the addition of nickel to the surface was also investigated. Theoretical analysis was carried out. Models for the process at the surface as well as in the bulk were developed. Diffusion equation was examined taking into account the diffusion coefficient being function of concentration. A non-linear differential equation resulted for this case. The differential equation was numerically solved.

  8. Does Mercury Have Lunar-like Mascons?

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Zuber, M. T.; Phillips, R. J.; Solomon, S. C.; Lemoine, F. G.; Neumann, G. A.; Head, J. W.; Torrence, M. H.

    2009-03-01

    In 2008 MESSENGER conducted two flybys of Mercury and experienced greater perturbation than expected. We investigated the possibility of gravity anomalies associated with surface features being the cause.

  9. Chronic mercury poisoning: Report of two siblings.

    PubMed

    Yilmaz, Cahide; Okur, Mesut; Geylani, Hadi; Caksen, Hüseyin; Tuncer, O?uz; Ata?, Bülent

    2010-01-01

    Mercury exists as organic inorganic and elementary forms in nature and is one of the most toxic metals that are poisonous for human beings. Mercury is commonly used in many different sectors of industry such as in insects formulas, agriculture products, lamps, batteries, paper, dyes, electrical/electronic devices, jewelry, and in dentistry. In this study, two siblings (one a 7-year-old boy and the other a 13 years old girl) are reported who developed chronic mercury poisoning as a result of long-term contact with batteries. Our aim is to emphasize the importance of mercury poisoning that is extremely rarely seen in childhood. PMID:20808663

  10. In the spotlight: Mercury containing lamps

    SciTech Connect

    O`Connell, K.A.

    1997-09-01

    This spring, under pressure from Congress, the US EPA agreed to release a long-awaited study on mercury pollution by the end of the year. The study is expected to shed light on the debate over whether mercury-containing lamps should be recycled--or whether they can be landfilled or incinerated. The 1990 amendments to the Clean Air Act mandated that EPA complete a study of mercury and submit it to Congress by November 1994. EPA completed the 1,700-page report in 1995, but, instead of submitting the study to Congress, the agency sent the report to the science Advisory Board for review because new studies on mercury were expected to require revisions to the report. The concurrent resolution outlines three actions EPA should take: (1) immediately release to Congress the study of mercury; (2) initiate a pilot program for landfill air emission tests for mercury in the northeast and nationally; and (3) not exempt mercury-containing lamps from hazardous waste regulations, but instead include mercury in universal waste rules that foster mercury recycling.

  11. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  12. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

    2002-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  13. Isotope effect of mercury diffusion in air.

    PubMed

    Koster van Groos, Paul G; Esser, Bradley K; Williams, Ross W; Hunt, James R

    2014-01-01

    Identifying and reducing impacts from mercury sources in the environment remains a considerable challenge and requires process based models to quantify mercury stocks and flows. The stable isotope composition of mercury in environmental samples can help address this challenge by serving as a tracer of specific sources and processes. Mercury isotope variations are small and result only from isotope fractionation during transport, equilibrium, and transformation processes. Because these processes occur in both industrial and environmental settings, knowledge of their associated isotope effects is required to interpret mercury isotope data. To improve the mechanistic modeling of mercury isotope effects during gas phase diffusion, an experimental program tested the applicability of kinetic gas theory. Gas-phase elemental mercury diffusion through small bore needles from finite sources demonstrated mass dependent diffusivities leading to isotope fractionation described by a Rayleigh distillation model. The measured relative atomic diffusivities among mercury isotopes in air are large and in agreement with kinetic gas theory. Mercury diffusion in air offers a reasonable explanation of recent field results reported in the literature. PMID:24364380

  14. Mercury concentrations in Maine sport fishes

    SciTech Connect

    Stafford, C.P. [Univ. of Maine, Orono, ME (United States)] [Univ. of Maine, Orono, ME (United States); Haines, T.A. [Geological Survey, Orono, ME (United States)] [Geological Survey, Orono, ME (United States)

    1997-01-01

    To assess mercury contamination of fish in Maine, fish were collected from 120 randomly selected lakes. The collection goal for each lake was five fish of the single most common sport fish species within the size range commonly harvested by anglers. Skinless, boneless fillets of fish from each lake were composited, homogenized, and analyzed for total mercury. The two most abundant species, brook trout Salvelinus fontinalis and smallmouth bass Micropterus dolomieu, were also analyzed individually. The composite fish analyses indicate high concentrations of mercury, particularly in large and long-lived nonsalmonid species. Chain pickerel Esox niger, smallmouth bass, largemouth bass Micropterus salmoides, and white perch Morone americana had the highest average mercury concentrations, and brook trout and yellow perch Perca flavescens had the lowest. The mean species composite mercury concentration was positively correlated with a factor incorporating the average size and age of the fish. Lakes containing fish with high mercury concentrations were not clustered near known industrial or population centers but were commonest in the area within 150 km of the seacoast, reflecting the geographical distribution of species that contained higher mercury concentrations. Stocked and wild brook trout were not different in length or weight, but wild fish were older and had higher mercury concentrations. Fish populations maintained by frequent introductions of hatchery-produced fish and subject to high angler exploitation rates may consist of younger fish with lower exposure to environmental mercury and thus contain lower concentrations than wild populations.

  15. EDITORIAL: Mercury-free discharges for lighting

    NASA Astrophysics Data System (ADS)

    Haverlag, M.

    2007-07-01

    This special Cluster of articles in Journal of Physics D: Applied Physics covers the subject of mercury-free discharges that are being investigated by different light source researchers, as an alternative to existing mercury-containing lamps. The main driving force to move away from mercury-containing discharge light sources is connected to the environmentally unfriendly nature of mercury. After inhalation or direct contact, severe mercury exposure can lead to damage to human brain cells, the kidneys, the liver and the nervous system. For this reason, the use of mercury in products is becoming more and more restricted by different governmental bodies. In the lighting industry, however, many products still make use of mercury, for different reasons. The main reason is that mercury-containing products are, in most cases, more efficient than mercury-free products. For a realistic comparison of the environmental impact, the mercury-contamination due to electricity production must be taken into account, which depends on the type of fuel being used. For an average European fuel-mix, the amount of mercury that is released into the environment is around 29 ?g kWh-1. This means that a typical 30 W TL lamp during a lifetime of 20,000 hours will release a total of about 20 mg mercury due to electricity production, which exceeds the total mercury dose in the lamp (more and more of which is being recycled) by a factor of 5-10 for a modern TL lamp. This illustrates that, quite apart from other environmental arguments like increased CO2 production, mercury-free alternatives that use more energy can in fact be detrimental for the total mercury pollution over the lifetime of the lamp. For this reason, the lighting industry has concentrated on lowering the mercury content in lamps as long as no efficient alternatives exist. Nevertheless, new initiatives for HID lamps and fluorescent lamps with more or less equal efficiency are underway, and a number of them are described in this special issue. These initiatives may in time offer realistic alternatives for mercury-containing discharge lamps as the efficiency gap with existing products is getting smaller. At the same time, new applications for radiation sources are becoming more important, and in some of them the presence of mercury has other disadvantages besides the environmental aspects. Since in most cases mercury is used in the form of a saturated vapour, the mercury pressure is dependent on the ambient temperature, which means that mercury-containing lamps often show a slow increase to the steady-state light output or a strongly reduced output in cold environments, which is undesirable in many applications. For this reason also, different options for light sources without mercury are being investigated, and a number of them can be found in this special issue. This collection of papers gives a good overview of the different technologies that are currently being investigated as alternatives to existing lamp technologies, and will surely inspire others to reduce the use of mercury for lighting applications.

  16. A deformation and thermodynamic model for hydride precipitation kinetics in spent fuel cladding

    SciTech Connect

    Stout, R.B.

    1989-10-01

    Hydrogen is contained in the Zircaloy cladding of spent fuel rods from nuclear reactors. All the spent fuel rods placed in a nuclear waste repository will have a temperature history that decreases toward ambient; and as a result, most all of the hydrogen in the Zircaloy will eventually precipitate as zirconium hydride platelets. A model for the density of hydride platelets is a necessary sub-part for predicting Zircaloy cladding failure rate in a nuclear waste repository. A model is developed to describe statistically the hydride platelet density, and the density function includes the orientation as a physical attribute. The model applies concepts from statistical mechanics to derive probable deformation and thermodynamic functionals for cladding material response that depend explicitly on the hydride platelet density function. From this model, hydride precipitation kinetics depend on a thermodynamic potential for hydride density change and on the inner product of a stress tensor and a tensor measure for the incremental volume change due to hydride platelets. The development of a failure response model for Zircaloy cladding exposed to the expected conditions in a nuclear waste repository is supported by the US DOE Yucca Mountain Project. 19 refs., 3 figs.

  17. Hollow Promises: A Window into Mercury’s Surface Mineralogy

    NASA Astrophysics Data System (ADS)

    Vilas, Faith; Domingue, Deborah L.; Helbert, Joern; D'Amore, Mario; Izenberg, Noam R.; Murchie, Scott L.; Klima, Rachel L.; Stockstill-Cahill, Karen R.; Sprague, Ann L.; Vaughan, William M.; Head, James W.

    2014-11-01

    Early in its orbital operations at Mercury, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft’s Mercury Dual-Imaging System (MDIS) began imaging "hollows" on the walls, rims, floors, and central peaks of impact craters. Hollows are shallow, irregular, rimless, flat-floored depressions, often with bright interiors and halos, are fresh in appearance, and have less steeply sloped spectral reflectance with wavelength than typical for Mercury. MDIS wide-angle camera (WAC) images obtained with eight narrow-band color filters from 433.2 nm to 996.2 nm of hollows in the craters Dominici (center latitude 1.38°N, longitude 323.5°E, ~20 km diameter), Hopper (12.4°S, 304.1°E, ~35 km), and Mistral (4.7°N, 305.4°E, ~100 km) have sufficient spatial resolution and repeatable color sets to examine spectral reflectance properties. The reflectance data, expressed as I/F, where I is light reflected from Mercury's surface and F is incident sunlight, were corrected for global geometric effects. Hollows on the south crater wall and rim of Dominici have well-defined depressions and halos that are a factor of ~1.4 brighter across the spectral range measured than those in the crater center. Hollows in the center of Dominici are factor of ~1.2 brighter than those in Hopper and Mistral. Eight color sets of Dominici show evidence for a spectral absorption feature centered near 700 nm in the hollows terrain. Three color sets of Hopper hollows show a spectral absorption feature diminished in depth compared to that for the Dominici hollows; the Mistral hollows show no discernible spectral absorption in two color sets. The reflectance differences are likely due to relative age of the hollows. At Dominici, we postulate that the hollows on the southern wall and rim were exposed to the local environment through a process of slumping of overlying material; it is likely that fresh material susceptible to hollow formation is regularly exposed. Local and global processes darken the hollows and diminish the spectral absorption feature. From laboratory reflectance studies of temperature effects on spectral properties of sulfides, these observations suggest that the hollows mineralogy incorporates low-density MgS.

  18. Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

    PubMed Central

    Harris, Reed C.; Rudd, John W. M.; Amyot, Marc; Babiarz, Christopher L.; Beaty, Ken G.; Blanchfield, Paul J.; Bodaly, R. A.; Branfireun, Brian A.; Gilmour, Cynthia C.; Graydon, Jennifer A.; Heyes, Andrew; Hintelmann, Holger; Hurley, James P.; Kelly, Carol A.; Krabbenhoft, David P.; Lindberg, Steve E.; Mason, Robert P.; Paterson, Michael J.; Podemski, Cheryl L.; Robinson, Art; Sandilands, Ken A.; Southworth, George R.; St. Louis, Vincent L.; Tate, Michael T.

    2007-01-01

    Methylmercury contamination of fisheries from centuries of industrial atmospheric emissions negatively impacts humans and wildlife worldwide. The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first 3 years of study. Essentially all of the increase in fish methylmercury concentrations came from mercury deposited directly to the lake surface. In contrast, <1% of the mercury isotope deposited to the watershed was exported to the lake. Steady state was not reached within 3 years. Lake mercury isotope concentrations were still rising in lake biota, and watershed mercury isotope exports to the lake were increasing slowly. Therefore, we predict that mercury emissions reductions will yield rapid (years) reductions in fish methylmercury concentrations and will yield concomitant reductions in risk. However, a full response will be delayed by the gradual export of mercury stored in watersheds. The rate of response will vary among lakes depending on the relative surface areas of water and watershed. PMID:17901207

  19. Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

    USGS Publications Warehouse

    Harris, R.C.; Rudd, J.W.M.; Amyot, M.; Babiarz, C.L.; Beaty, K.G.; Blanchfield, P.J.; Bodaly, R.A.; Branfireun, B.A.; Gilmour, C.C.; Graydon, J.A.; Heyes, A.; Hintelmann, H.; Hurley, J.P.; Kelly, C.A.; Krabbenhoft, D.P.; Lindberg, S.E.; Mason, R.P.; Paterson, M.J.; Podemski, C.L.; Robinson, A.; Sandilands, K.A.; Southworthn, G.R.; St. Louis, V.L.; Tate, M.T.

    2007-01-01

    Methylmercury contamination of fisheries from centuries of industrial atmospheric emissions negatively impacts humans and wild-life worldwide. The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first 3 years of study. Essentially all of the increase in fish methylmercury concentrations came from mercury deposited directly to the lake surface. In contrast, <1% of the mercury isotope deposited to the watershed was exported to the lake. Steady state was not reached within 3 years. Lake mercury isotope concentrations were still rising in lake biota, and watershed mercury isotope exports to the lake were increasing slowly. Therefore, we predict that mercury emissions reductions will yield rapid (years) reductions in fish methylmercury concentrations and will yield concomitant reductions in risk. However, a full response will be delayed by the gradual export of mercury stored in watersheds. The rate of response will vary among lakes depending on the relative surface areas of water and watershed. ?? 2007 by The National Academy of Sciences of the USA.

  20. Children's health and mercury exposure

    Microsoft Academic Search

    Roberto Ronchetti; Moniek Zuurbier; Milos Jesenak; JANNA G. KOPPE; Ubah Farah Ahmed; Sandra Ceccatelli; Maria Pia Villa

    2006-01-01

    The reason why mercury is dangerous is that once released into the environment it cannot be removed and is rapidly transformed by microorganisms into organic compounds that tend to bioaccumulate and biomagnify in animals. The principal organic compound is methylmercury (MeHg). The primary route of exposure to MeHg for humans is consumption of fish. The safe dose (reference dose, RfD)

  1. Mercury speciation in Lake Baikal

    Microsoft Academic Search

    C. Meuleman; M. Leermakers; W. Baeyens

    1995-01-01

    Research on mercury (Hg) distribution and speciation was carried out in Lake Baikal, a large, strong-oligotrophic freshwater reservoir in Siberia, Russia, during June 1992 and march 1993. In summer, total Hg in the water column ranged from 0.14 to 0.77 ng Hg\\/L, with the highest concentrations observed in the central basin of the lake in surface water samples. Labile inorganic

  2. Mercury in the North Atlantic

    Microsoft Academic Search

    R. P Mason; K. R Rolfhus; W. F Fitzgerald

    1998-01-01

    Reactive mercury (Hg) concentrations (0.80±0.44 pM), measured during a cruise in the sub-polar North Atlantic (50–70°N) in August 1993 were lower those of more southerly regions of this ocean. A large fraction of the Hg in the surface waters was elemental Hg (Hg°; 88% of the reactive Hg, on average; 0.65±0.50 pM). Little dimethylmercury (DMHg) or monomethylmercury (MMHg) was found

  3. Mercury separation from aqueous wastes

    Microsoft Academic Search

    P. A. Taylor; K. T. Klasson; S. L. Corder

    1995-01-01

    This project is providing an assessment of new sorbents for removing mercury from wastes at US Department of Energy sites. Four aqueous wastes were chosen for lab-scale testing; a high-salt, acidic waste currently stored at Idaho National Engineering Laboratory (INEL); a high-salt, alkaline waste stored at the Savannah River Site (SRS); a dilute lithium hydroxide solution stored at the Oak

  4. Mercury contamination of fish and shrimp samples available in markets of Mashhad, Iran.

    PubMed

    Vahabzadeh, Maryam; Balali-Mood, Mahdi; Mousavi, Seyed-Reza; Moradi, Valiollah; Mokhtari, Mehrangiz; Riahi-Zanjani, Bamdad

    2013-09-01

    Fish and shrimp are common healthy sources of protein to a large percentage of the world's population. Hence, it is vital to evaluate the content of possible contamination of these marine-foods. Six species of fishes and two species of shrimps were collected from the local markets of Mashhad, Iran. The mercury (Hg) concentration of samples was determined by atomic absorption spectrophotometry using a mercuric hydride system (MHS 10). High concentration of total Hg was found in Clupeonella cultriventris caspia (0.93 ± 0.14 ?g/g) while the lowest level was detected in Penaeus indicus (0.37 ± 0.03 ?g/g). Mean Hg levels in fish and shrimp samples were 0.77 ± 0.08 ?g/g and 0.51 ± 0.05 ?g/g, respectively. Farmed species (except for P. indicus) and all samples from Persian Gulf and the Caspian Sea had mean mercury concentrations above 0.5 ?g/g, which is the maximum standard level recommended by Joint FAO/WHO/Expert Committee on Food Additives (JECFA). All samples had also mean Hg concentrations that exceeded EPA's established safety level of 0.3 ?g/g. A little more extensive analysis of data showed that weekly intake of mercury for the proportion of the Iranian population consuming Hg contaminated fish and shrimp is not predicted to exceed the respective provisional tolerable weekly intakes recommended by JECFA. However, the Iranian health and environmental authorities should monitor Hg contamination of the fishes and shrimps before marketing. PMID:23903758

  5. Investigating Atmospheric Mercury with the U.S. Geological Survey Mobile Mercury Laboratory

    USGS Publications Warehouse

    Kolker, Allan

    2007-01-01

    Atmospheric mercury is thought to be an important source of mercury present in fish, resulting in numerous local, statewide, tribal, and province-wide fish consumption advisories in the United States and Canada (U.S. Environmental Protection Agency, 2007a). To understand how mercury occurs in the atmosphere and its potential to be transferred from the atmosphere to the biosphere, the U.S. Geological Survey (USGS) has been investigating sources and forms of atmospheric mercury, especially in locations where the amount of mercury deposited from precipitation is above average.

  6. Magnetic properties of the intermetallic compounds RNi (R=Gd, Tb, Dy, Sm) and their hydrides

    Microsoft Academic Search

    Yu. L. Yaropolov; V. N. Verbetsky; A. S. Andreenko; K. O. Berdyshev; S. A. Nikitin

    2010-01-01

    Hydrogen interaction with RNi intermetallic compounds and the influence of hydrogen on magnetic properties of these compounds\\u000a were investigated. Ternary hydrides GdNiH3.2, TbNiH3.4, DyNiH3.4 and SmNiH3.7 were prepared by hydrogenation of the initial alloys at room temperature and hydrogen pressure up to 0.1 MPa. Hydrides possess\\u000a orthorhombic CrB-type structure (S.G. Cmcm). The formation of hydrides results in substantial expansion of

  7. Recovery of Mercury From Contaminated Liquid Wastes

    SciTech Connect

    NONE

    1998-06-12

    The Base Contract program emphasized the manufacture and testing of superior sorbents for mercury removal, testing of the sorption process at a DOE site, and determination of the regeneration conditions in the laboratory. During this project, ADA Technologies, Inc. demonstrated the following key elements of a successful regenerable mercury sorption process: (1) sorbents that have a high capacity for dissolved, ionic mercury; (2) removal of ionic mercury at greater than 99% efficiency; and (3) thermal regeneration of the spent sorbent. ADA's process is based on the highly efficient and selective sorption of mercury by noble metals. Contaminated liquid flows through two packed columns that contain microporous sorbent particles on which a noble metal has been finely dispersed. A third column is held in reserve. When the sorbent is loaded with mercury to the point of breakthrough at the outlet of the second column, the first column is taken off-line and the flow of contaminated liquid is switched to the second and third columns. The spent column is regenerated by heating. A small flow of purge gas carries the desorbed mercury to a capture unit where the liquid mercury is recovered. Laboratory-scale tests with mercuric chloride solutions demonstrated the sorbents' ability to remove mercury from contaminated wastewater. Isotherms on surrogate wastes from DOE's Y-12 Plant in Oak Ridge, Tennessee showed greater than 99.9% mercury removal. Laboratory- and pilot-scale tests on actual Y-12 Plant wastes were also successful. Mercury concentrations were reduced to less than 1 ppt from a starting concentration of 1,000 ppt. The treatment objective was 50 ppt. The sorption unit showed 10 ppt discharge after six months. Laboratory-scale tests demonstrated the feasibility of sorbent regeneration. Results show that sorption behavior is not affected after four cycles.

  8. Investigations on the toxic effects of different mercury compounds on young, white leghorn cocks

    Microsoft Academic Search

    A. Swensson; U. Ulfvarson

    1969-01-01

    Th toxic effects of several mercury seed dressings on 10 wk old leghorn cocks were studied. The mercury compounds included mercury nitrate, methyl mercury hydroxide, methoxyethyl mercury hydroxide and phenyl mercury hydroxide. Approximate lethal dosage for a single intravenous injection was obtained and the effects of both high- and low-concentration mercury diets were studied.

  9. The Mercury Gravity Field: MESSENGER Observations

    Microsoft Academic Search

    D. E. Smith; M. T. Zuber; R. J. Phillips; S. C. Solomon; S. J. Peale; F. G. Lemoine; M. H. Torrence; M. Perry; S. A. Hauck; J. Margot; J. Oberst; C. L. Johnson

    2008-01-01

    On January 14, 2008, the MESSENGER spacecraft passed within 201 km of the surface of the planet Mercury with a closest approach at 4S, 38E. This was the first of three MESSENGER flybys of the planet, and it provided the first observations of Mercury from a spacecraft since the Mariner 10 flybys in 1974 and 1975. The tracking of the

  10. Mercury capture on coal combustion fly ash

    Microsoft Academic Search

    David J Hassett; Kurt E Eylands

    1999-01-01

    A study was performed at the Energy and Environmental Research Center (EERC) to test the hypotheses that (1) different carbon types contained in coal combustion fly ash have variable sorption capabilities relative to mercury and (2) the inorganic fraction of coal combustion fly ash may sorb mercury through mechanisms distinct from sorption by carbon in the ash. The purpose of

  11. Modeling Mercury Removal by Sorbent Injection

    Microsoft Academic Search

    Frank B. Meserole; Ramsay Chang; Todd R. Carey; James Machac; Carl F. Richardson

    1999-01-01

    Sorbents for removing mercury from flue gases of coal-fired power plants are presently being evaluated due to potential regulation of mercury emissions under Title III of the 1990 Clean Air Act Amendments. Laboratory tests have been conducted to evaluate the adsorption characteristics of potential sorbents and the effects of flue gas constituents on these characteristics. This paper presents a theoretical

  12. Human impacts on open ocean mercury concentrations

    Microsoft Academic Search

    Elsie M. Sunderland; Robert P. Mason

    2007-01-01

    We develop an empirically constrained multicompartment box model for mercury cycling in open ocean regions to investigate changes in concentrations resulting from anthropogenic perturbations of the global mercury cycle. Using Monte Carlo simulations, we explicitly consider the effects of variability in measured parameters on modeled seawater concentrations. Our simulations show that anthropogenic enrichment in all surface (25%) and deep ocean

  13. Human impacts on open ocean mercury concentrations

    Microsoft Academic Search

    Elsie M. Sunderland; Robert P. Mason

    2007-01-01

    (1)We develop an empirically constrained multicompartment box model for mercury cycling in open ocean regions to investigate changes in concentrations resulting from anthropogenic perturbations of the global mercury cycle. Using Monte Carlo simulations, we explicitly consider the effects of variability in measured parameters on modeled seawater concentrations. Our simulations show that anthropogenic enrichment in all surface (25%) and deep ocean

  14. SELECTIVE CATALYTIC REDUCTION MERCURY FIELD SAMPLING PROJECT

    EPA Science Inventory

    The report details an investigation on the effect of selective catalytic reduction (SCR), selective noncatalytic reduction (SNCR), and flue gas conditioning on the speciation and removal of mercury at power plants. If SCR and/or SNCR systems enhance mercury conversion/capture, t...

  15. Dental amalgam and mercury in dentistry

    Microsoft Academic Search

    AJ Spencer

    2000-01-01

    Mercury in dentistry has re-emerged as a contentious issue in public health, predominantly because so many people are inadvertently exposed to mercury in order to obtain the benefits of dental amalgam fillings, and the risks remain difficult to interpret. This commentary aims to examine the issues involved in public policy assessment of the continued use of dental amalgam in dentistry.

  16. Purification of mercury contaminated lithium hydroxide

    Microsoft Academic Search

    B. R. Bronfin; D. M. Jenkins; E. E. Jr. Wright

    1960-01-01

    The object of this investigation was to determine an economical method of preparing pure lithium hydroxide from a mercury-contaminated lithium hydroxide monohydrate salt presently produced as a waste product. Pure lithium hydroxide has application for chemical removal of carbon dioxide from air and general open market sale if the mercury contamination is reduced to approximately one part per billion. Because

  17. The MESSENGER mission to Mercury: scientific payload

    Microsoft Academic Search

    Robert E. Gold; Sean C. Solomon; Ralph L. McNutt; Andrew G. Santo; James B. Abshire; Mario H. Acuña; Robert S. Afzal; Brian J. Anderson; G. Bruce Andrews; Peter D. Bedini; J. Cheng Cain; Andrew F. Cheng; Larry G. Evans; William C. Feldman; Ronald B. Follas; George Gloeckler; John O. Goldsten; S. Edward Hawkins III; Noam R. Izenberg; Stephen E. Jaskulek; Eleanor A. Ketchum; Mark R. Lankton; David A. Lohr; Barry H. Mauk; William E. McClintock; Scott L. Murchie; Charles E. Schlemm II; David E. Smith; Richard D. Starr; Thomas H. Zurbuchen

    2001-01-01

    The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission will send the first spacecraft to orbit the planet Mercury. A miniaturized set of seven instruments, along with the spacecraft telecommunications system, provide the means of achieving the scientific objectives that motivate the mission. The payload includes a combined wide- and narrow-angle imaging system; ?-ray, neutron, and X-ray spectrometers for

  18. Calcium in Mercury's Exosphere: Modeling MESSENGER Data

    NASA Astrophysics Data System (ADS)

    Burger, M. H.; Killen, R. M.; McClintock, W. E.; Vervack, R. J., Jr.; Sprague, A. L.

    2011-10-01

    Although neutral calcium was discovered from ground-based observations of Mercury's exosphere, the first high-spatial-resolution observations were made by the MESSENGER spacecraft. The Monte Carlo model of the exosphere we have developed to simulate the observations from the Mercury flybys and early orbits suggests a high-energy source of Ca concentrated in the dawn, equatorial region.

  19. Mercury in tropical and subtropical coastal environments

    PubMed Central

    Costa, Monica F.; Landing, William M.; Kehrig, Helena A.; Barletta, Mário; Holmes, Christopher D.; Barrocas, Paulo R. G.; Evers, David C.; Buck, David G.; Vasconcellos, Ana Claudia; Hacon, Sandra S.; Moreira, Josino C.; Malm, Olaf

    2012-01-01

    Anthropogenic activities influence the biogeochemical cycles of mercury, both qualitatively and quantitatively, on a global scale from sources to sinks. Anthropogenic processes that alter the temporal and spatial patterns of sources and cycling processes are changing the impacts of mercury contamination on aquatic biota and humans. Human exposure to mercury is dominated by the consumption of fish and products from aquaculture operations. The risk to society and to ecosystems from mercury contamination is growing, and it is important to monitor these expanding risks. However, the extent and manner to which anthropogenic activities will alter mercury sources and biogeochemical cycling in tropical and sub-tropical coastal environments is poorly understood. Factors as (1) lack of reliable local/regional data; (2) rapidly changing environmental conditions; (3) governmental priorities and; (4) technical actions from supra-national institutions, are some of the obstacles to overcome in mercury cycling research and policy formulation. In the tropics and sub-tropics, research on mercury in the environment is moving from an exploratory “inventory” phase towards more process-oriented studies. Addressing biodiversity conservation and human health issues related to mercury contamination of river basins and tropical coastal environments are an integral part of paragraph 221 paragraph of the United Nations document “The Future We Want” issued in Rio de Janeiro in June 2012. PMID:22901765

  20. Mercury's atmosphere - A perspective after Mariner 10

    Microsoft Academic Search

    S. Kumar

    1976-01-01

    Implications of Mariner 10 observations are discussed regarding the composition and structure of Mercury's atmosphere as well as its interaction with the solar wind. The Mariner 10 data cited indicate that Mercury's atmosphere is apparently similar to that on the moon. It is shown that helium could be supplied to the atmosphere either by the radioactive decay of uranium and

  1. Mercury exposure in children: a review

    Microsoft Academic Search

    S. Allen Counter; Leo H. Buchanan

    2004-01-01

    Exposure to toxic mercury (Hg) is a growing health hazard throughout the world today. Recent studies show that mercury exposure may occur in the environment, and increasingly in occupational and domestic settings. Children are particularly vulnerable to Hg intoxication, which may lead to impairment of the developing central nervous system, as well as pulmonary and nephrotic damage. Several sources of

  2. REGIONAL PATTERNS OF WET MERCURY DEPOSITION

    EPA Science Inventory

    Most of the mercury contamination in lakes and streams of nonindustrialized regions of the United States and Canada is derived from atmospheric deposition. In order to determine the regional patterns of these inputs, seven mercury-in-precipitation monitoring sites were establishe...

  3. Momument at Pad 14 honoring Project Mercury

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Momument at Pad 14 honoring Project Mercury. The Arabic number 7 represents the seven original astronauts. The other figure is the astronomical symbol of the Planet Mercury. In background is the Gemini 12 Agena Target Docking Vehicle atop its Atlas launch vehicle at Cape Kennedy, Florida.

  4. Low dose mercury toxicity and human health

    Microsoft Academic Search

    Farhana Zahir; Shamim J. Rizwi; Soghra K. Haq; Rizwan H. Khan

    2005-01-01

    Post Minamata incident there has been awareness about mercury toxicity even among the general public. Previous researches contributed a vast amount of data regarding acute mercury exposure, but gradually information about the low dose [Ninomiya, T., Ohmori, H., Hashimoto, K., Tsuruta, K., Ekino, S., 1995. Expansion of methylmercury poisoning outside minamata: an epidemiological study on chronic methylmercury poisoninig outside of

  5. A Review of Mercury in Seafood

    Microsoft Academic Search

    Rosalee S. Rasmussen; Joyce Nettleton; Michael T. Morrissey

    2005-01-01

    Mercury is a toxic heavy metal released into the environment from both natural and anthropogenic sources. It is of great interest to consumers as to whether it can cause neurological effects at low dose levels. The effects of organic mercury exposure at high levels have been demonstrated in several large-scale poisonings, particularly those in Japan and Iraq in the 1950s,

  6. Mercury's sodium exosphere: Magnetospheric ion recycling

    Microsoft Academic Search

    F. Leblanc; D. Delcourt; R. E. Johnson

    2003-01-01

    A three-dimensional Monte Carlo model of Mercury's neutral sodium exosphere was used to describe correlation between the observed variations in the exospheric density and the variations in the surface concentration of sodium along Mercury's motion around the Sun [Leblanc and Johnson, 2003]. Four processes of ejection were taken into account: thermal and photon stimulated desorptions, solar wind sputtering, and micrometeoroid

  7. US mercury recyclers provide expanded process capabilities

    Microsoft Academic Search

    P. B. Queneau; L. A. Smith

    1994-01-01

    In the United States today, emphasis is on minimizing use of and exposure to mercury. Mercury-contaminated materials are treated for Hg recovery before being landfilled. Major feedstocks include batteries, thermometers, switches, thermocouples, chloralkali waste, charcoal, lighting wastes, chloralkali waste, charcoal, lighting wastes, residues from remediation activities and soils. Major soil sources include natural gas pipelines, and DOE sites. There is

  8. US mercury recyclers provide expanded process capabilities

    SciTech Connect

    Queneau, P.B. (Hazen Research, Golden, CO (United States)); Smith, L.A. (Battelle Memorial Inst., Columbus, OH (United States))

    1994-02-01

    In the United States today, emphasis is on minimizing use of and exposure to mercury. Mercury-contaminated materials are treated for Hg recovery before being landfilled. Major feedstocks include batteries, thermometers, switches, thermocouples, chloralkali waste, charcoal, lighting wastes, chloralkali waste, charcoal, lighting wastes, residues from remediation activities and soils. Major soil sources include natural gas pipelines, and DOE sites. There is also substantial recycling of flowable mercury using triple distillation. US mercury consumption is about one-third that of five years ago, reflecting restricted use of the hazardous metal to essential applications for which there is no viable substitute. Apparent US mercury consumption in 1992 was about 1.4 million pounds. About 40 percent of this volume was used in measurement and control instruments, and dental applications. Approximately 30 percent was used in the chloralkali industry, and most of the balance was used in electrical and electronic applications. The supply of mercury needed by domestic consumers is met by output from domestic mercury recycling companies. This article summarizes the treatment capabilities of US plants that recover mercury from various secondary sources.

  9. MERCURY IN MINING CONFERENCE PROCEEDINGS DOCUMENT

    EPA Science Inventory

    Mercury deposits in mines have shown to pose a significant hazard to residents and wildlife where drainage from these deposits enters the ecosystem through streams and rivers. For this reason, the extent of mercury contamination in the United States is of significant environment...

  10. EMISSION RATES OF MERCURY FROM LATEX PAINTS

    EPA Science Inventory

    The paper gives results of tests of latex paints containing organic mercury additives in small environmental test chambers to determine the emission rates of mercury. Five paints were evaluated: two contained phenyl mercuric acetate (PMA); and the other three, different additives...

  11. Mercury in a marine pelagic food chain

    Microsoft Academic Search

    GEORGE A. KNAUER; JOHN H. MARTIN

    1972-01-01

    Phytoplankton, zooplankton, and anchovies collected in Monterey Bay, California, over a 10-month period were analyzed for total mercury. In general, mercury levels were low and no evidence of food chain amplification was observed. Temporal variations of Hg concentrations in phytoplankton were greater than those for zooplankton; however, no seasonal trends were observed for either group. Plankton samples were also collected

  12. Mercury soil surveys: a good reconnaissance tool

    SciTech Connect

    Stone, C.; Ruscetta, C.A.; Foley, D. (eds.)

    1981-05-01

    Three examples of mercury soil surveys are discussed, along with the gravity data. An excellent correlation was found in southern Arizona between buried structures revealed by gravity and mercury soil surveys. The advantages of the latter over the former as a reconnaissance tool are listed. (MHR)

  13. Biomodification of coal to remove mercury.

    PubMed

    Klasson, K Thomas; Borole, Abhijeet P; McKeown, Catherine K; Hamilton, Choo Y

    2006-03-01

    A biological process for removal of mercury from coal is under investigation. Iron and sulfur oxidizing bacteria have previously been used for desulfurization of coal and for mineral mining. We have shown that removal of mercury from coal is also possible via the same principles. Two pure cultures, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans and four environmental consortium samples obtained from an acid mine drainage site were studied for mercury removal from coal. Four different coal samples were included in the study and the preliminary results have shown that up to 20% of the mercury can be removed in batch cultures compared to control. Additional parameters such as media composition and inoculum size were also studied. This is the first report demonstrating successful leaching of mercury from coal using biological treatment. PMID:18563664

  14. Biomodification of coal to remove mercury.

    PubMed

    Klasson, K Thomas; Borole, Abhijeet P; McKeown, Catherine K; Hamilton, Choo Y

    2006-01-01

    A biological process for removal of mercury from coal is under investigation. Iron and sulfur oxidizing bacteria have previously been used for desulfurization of coal and for mineral mining. We have shown that removal of mercury from coal is also possible via the same principles. Two pure cultures, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans and four environmental consortium samples obtained from an acid mine drainage site were studied for mercury removal from coal. Four different coal samples were included in the study and the preliminary results have shown that up to 20% of the mercury can be removed in batch cultures compared to control. Additional parameters such as media composition and inoculum size were also studied. This is the first report demonstrating successful leaching of mercury from coal using biological treatment. PMID:16915698

  15. Aerospect operations criteria for Mercury thresholds

    NASA Technical Reports Server (NTRS)

    Katz, S.

    1979-01-01

    The hazards anticipated from a large scale mercury spill during a possible failure in the preflight and early flight stages of the Space Shuttle were studied. Toxicity thresholds were investigated as well as other consequences of mercury interacting with the environment. Three sites of mercury spill were investigated: land, water, and atmosphere. A laboratory study of interactions between mercury vapor and ozone in a low pressure, high ultraviolet radiation environment approximated the conditions of a mercury vapor release in the ozone layer region of the stratosphere. Clear evidence of an interaction leading to the destruction of ozone by conversion to oxygen was obtained. The impact of a spill on the Earth's environment and methods of early detection of a developing hazard wave of primary concern in the study.

  16. Mercury removal from solid mixed waste

    SciTech Connect

    Gates, D.D.; Morrissey, M.; Chava, K.K.; Chao, K.

    1994-12-31

    The removal of mercury from mixed wastes is an essential step in eliminating the temporary storage of large inventories of mixed waste throughout the Department of Energy (DOE) complex. Currently thermal treatment has been identified as a baseline technology and is being developed as part of the DOE Mixed Waste Integrated Program (MWIP). Since thermal treatment will not be applicable to all mercury containing mixed waste and the removal of mercury prior to thermal treatment may be desirable, laboratory studies have been initiated at Oak Ridge National Laboratory (ORNL) to develop alternative remediation technologies capable of removing mercury from certain mixed waste. This paper describes laboratory investigations of the KI/I{sub 2} leaching processes to determine the applicability of this process to mercury containing solid mixed waste.

  17. Short-Lived Proton Entanglement in Yttrium Hydrides

    NASA Astrophysics Data System (ADS)

    Karlsson, E. B.; Abdul-Redah, T.; Udovic, T. J.; Hjörvarsson, B.; Chatzidimitriou-Dreismann, C. A.

    2002-10-01

    Previous experiments on NbH0.8 and PdH0.6 have shown large anomalies in the cross sections for protons, when studied by neutron Compton scattering. Here, these investigations are extended to the metallic hydrides YH2, YH3, YD2, YD3, and Y(HxD1-x)3. Considerably reduced cross sections for hydrogen are observed both in YH2 and YH3, but only minor ones for YD2 and YD3. The scattering time depends on the neutron scattering angle, which allows a time-differential analysis where the time window lies around one femtosecond. The anomalies persist longer in YH2 and YH3 than in NbH0.8 and PdHo.6 The reduced cross sections are interpreted as a result of quantum entanglement between protons, surviving for a few fs in the solids.

  18. Optical transmission spectroscopy of switchable yttrium hydride films

    NASA Astrophysics Data System (ADS)

    Kremers, M.; Koeman, N. J.; Griessen, R.; Notten, P. H. L.; Tolboom, R.; Kelly, P. J.; Duine, P. A.

    1998-02-01

    The optical transmission of the recently discovered switchable yttrium hydride films is determined spectroscopically as a function of hydrogen content. This is done during electrochemical loading of Pd-capped Y film electrodes, thereby continuously changing the hydrogen concentration. The effect of the Pd cap layer on the film transmission is determined from measurements on a series of films with varying Pd layer thickness. The results are in good agreement with transmission measurements of in situ gas phase loaded, uncapped Y films. Both data sets can be consistently described with simple optical decay lengths such as 277.8 nm for YH3-? and 15.1 nm for Pd at ??=1.96 eV. The hydrogen concentration dependence of the optical transmission is discussed and compared with previous optical measurements on bulk samples and band-structure calculations.

  19. Short-lived proton entanglement in yttrium hydrides

    NASA Astrophysics Data System (ADS)

    Karlsson, E. B.; Abdul-Redah, T.; Udovic, T. J.; Hjörvarsson, B.; Chatzidimitriou-Dreismann, C. A.

    Earlier experiments on NbH0.8 and PdH0.6 have shown large anomalies in the cross sections for protons, when studied by neutron Compton scattering. Here, these investigations are extended to the metallic hydrides YH2, YH3, YD2, YD3, and Y(HxD1-x)3. Strongly reduced cross sections for hydrogen are observed both in YH2 and YH3, but only minor ones for YD2 and YD3. The scattering time depends on the neutron-scattering angle, which allows a time-differential analysis where the time window lies at around one femtosecond. The anomalies persist longer in YH2 and YH3 than in NbH0.8 and PdH0.6. The reduced cross sections are interpreted as a result of quantum entanglement between protons, surviving for a few femtoseconds in the solids.

  20. UV inverse photoemission from cerium and its hydrides

    NASA Astrophysics Data System (ADS)

    Osterwalder, J.; Schlapbach, L.

    1984-11-01

    Isochromate spectra of polycrystalline Ce, CeH 2.1 and CeH 2.9 were measured at a photon energy of 9.7 eV. The intensity at E F is 4 to 5 times lower on CeH 2.1 than it is on the metal, and it vanishes on CeH 2.9. This is in accordance with XPS, UPS and conductivity data. In both hydrides broad features ( ˜2 eV FWHM) appear, centered between 4 and 5 eV. From cross section arguments and from comparison with a CeRu 2 spectrum taken at the same photon energy, we conclude that we do not see any 4f contribution in our spectra. A signal at 7 eV on the CeH 2.9 spectrum is assigned to the 2? +u shape resonance of the H 2- ion, formed by desorbed H 2 molecules.

  1. Comparison of delayed hydride cracking behavior of two zirconium alloys

    NASA Astrophysics Data System (ADS)

    Ponzoni, L. M. E.; Mieza, J. I.; De Las Heras, E.; Domizzi, G.

    2013-08-01

    Delayed hydride cracking (DHC) is an important failure mechanism that may occur in Zr alloys during service in water-cooled reactors. Two conditions must be attained to initiate DHC from a crack: the stress intensity factor must be higher than a threshold value called KIH and, hydrogen concentration must exceed a critical value. Currently the pressure tubes for CANDU reactor are fabricated from Zr-2.5Nb. In this paper the critical hydrogen concentration for DHC and the crack velocity of a developmental pressure tube, Excel, was evaluated and compared with that of Zr-2.5Nb. The DHC velocity values measured in Excel were higher than usually reported in Zr-2.5Nb. Due to the higher hydrogen solubility limits in Excel, its critical hydrogen concentration for DHC initiation is 10-50 wppm over that of Zr-2.5Nb in the range of 150-300 °C.

  2. Modelling zirconium hydrides using the special quasirandom structure approach.

    PubMed

    Wang, H; Chroneos, A; Jiang, C; Schwingenschlögl, U

    2013-05-28

    The study of the structure and properties of zirconium hydrides is important for understanding the embrittlement of zirconium alloys used as cladding in light water nuclear reactors. Simulation of the defect processes is complicated due to the random distribution of the hydrogen atoms. We propose the use of the special quasirandom structure approach as a computationally efficient way to describe this random distribution. We have generated six special quasirandom structure cells based on face centered cubic and face centered tetragonal unit cells to describe ZrH(2-x) (x = 0.25-0.5). Using density functional theory calculations we investigate the mechanical properties, stability, and electronic structure of the alloys. PMID:23588997

  3. A resonant state and the ground state of positronium hydride

    NASA Technical Reports Server (NTRS)

    Ho, Y. K.

    1978-01-01

    The lowest-lying resonance occurring in S-wave positronium-hydrogen scattering is reinvestigated, using the complex-rotation method. By employing a generalized Hylleraas-type wave function that includes all six interparticle coordinates, a very accurate value of the resonance position is obtained, along with a good value of the width. The present result for the resonance position (-1.205 plus or minus 0.001 Ry) is lower than the previous result of Drachman and Houston, who omitted the interelectronic coordinate in their trial function. In addition, the lowest ground-state energy of positronium hydride is obtained by using 210 terms in the trial wave function. The effect of the interelectronic coordinate and others on both the resonant energy and the binding energy of PsH is discussed.

  4. LaNi5 hydride cryogenic refrigerator test results

    NASA Technical Reports Server (NTRS)

    Jones, J. A.

    1983-01-01

    A complete LaNi5 hydrogen absorption cryogenic refrigerator system was developed. The system uses low temperature waste heat of approximately 100 C as a power source, and has no moving parts other than self operating valves. The cycle continues automatically by an electronic sequencing timing mechanism for the three compressors which are phased such that a constant supply of high pressure hydrogen gas is provided. It is indicated that with a fully clean hydrogen system, hundreds of thousand cycles should be attainable, even though some degradation may eventually occur. Simple vacuum reactivation of the hydride of moving parts, other than self operating, long life valves, the refrigerators predicted life is extremely long.

  5. Hydrogen generation from magnesium hydride by using organic acid

    NASA Astrophysics Data System (ADS)

    Ho, Yen-Hsi

    In this paper, the hydrolysis of solid magnesium hydride has been studied with the high concentration of catalyst at the varying temperature. An organic acid (acetic acid, CH3COOH) has been chosen as the catalyst. The study has three objectives: first, using three different weights of MgH 2 react with aqueous solution of acid for the hydrogen generation experiments. Secondly, utilizing acetic acid as the catalyst accelerates hydrogen generation. Third, emphasizing the combination of the three operating conditions (the weight of MgH2, the concentration of acetic acid, and the varying temperature) influence the amount of hydrogen generation. The experiments results show acetic acid truly can increase the rate of hydrogen generation and the weight of MgH2 can affect the amount of hydrogen generation more than the varying temperature.

  6. Bipolar nickel-metal hydride battery for hybrid vehicles

    NASA Astrophysics Data System (ADS)

    Reisner, David E.; Klein, Martin

    1994-05-01

    Hybrid electric vehicles are receiving increased interest as an approach to decrease vehicle pollution, dependence, and consumption of liquid petroleum and meet forthcoming government vehicle emission standards. A number of schemes are under consideration (heat engine battery, fuel cell battery, peaking battery, inner-city battery, etc.). The success of any of the approaches will be dependent on battery capabilities, i.e., power, density, life, and cost. The nickel-metal hydride system appears to be the most promising of the candidate battery chemistries. Preliminary designs and analysis have been prepared and are presented for various configurations. Initial performance characterization tests are presented. It is concluded that a bipolar package arrangement for the Ni-MH chemistry appears most suited for the hybrid vehicle application considered.

  7. Determination of mercury in environmental samples: a constant challenge

    SciTech Connect

    Ferguson, N M

    1980-01-01

    A method for the determination of mercury in environmental samples is described. The laboratory maintenance for low mercury contamination in air and glassware is also described. Sample preparation is discussed. Mercury analysis is performed by cold vapor atomic absorption. This method can measure mercury content at concentration levels ranging from parts-per-trillion to mg/g. (DC)

  8. Sublethal concentrations of mercury in river otters: Monitoring environmental contamination

    Microsoft Academic Search

    R. S. Halbrook; J. H. Jenkins; P. B. Bush; N. D. Seabolt

    1994-01-01

    Hair, muscle, and liver mercury concentrations were determined in river otter (Lutra canadensis) carcasses collected from the lower coastal plain and piedmont of Georgia. Mean muscle and hair mercury concentrations were greater (PMustela vison), indicate sublethal contamination with concentrations in some individuals approaching that observed in experimentally dosed individuals that developed clinical signs of mercurialism. Mercury concentrations in fish from

  9. Mercury sensitisation: review, relevance and a clinical report

    Microsoft Academic Search

    K. Loomba; A. Loomba; R. Bains; V. K. Bains

    2008-01-01

    Eczematous eruptions may be produced through topical contact with mercury and by systemic absorption in mercury sensitive individuals. Mercury is considered a weak sensitiser and contact with mercury salts such as chloride or ammonium chloride may cause hypersensitivity leading to contact dermatitis or Coomb's Type IV hypersensitivity reactions. The typical manifestation is an urticarial or erythematous rash, and pruritis on

  10. Global circulation of atmospheric mercury: a modelling study

    Microsoft Academic Search

    Ashu P. Dastoor; Yvan Larocque

    2004-01-01

    This paper presents a comprehensive atmospheric global and regional mercury model and its capability in describing the atmospheric cycling of mercury. This is an on-line model (integrated within the Canadian operational environmental forecasting and data assimilation system) which can be used to understand the role of meteorology in mercury cycling (atmospheric pathways), the inter-annual variability of mercury and can be

  11. Mercury in the Pelagic Food Web of Lake Champlain

    PubMed Central

    Chen, Celia; Kamman, Neil; Shanley, James; Chalmers, Ann; Jackson, Brian; Taylor, Vivien; Smeltzer, Eric; Stangel, Pete; Shambaugh, Angela

    2013-01-01

    Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25 to 75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 µg g?1 in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury. PMID:22193540

  12. A MODELLING FRAMEWORK FOR MERCURY CYCLING IN LAKE MICHIGAN

    EPA Science Inventory

    A time-dependent mercury model was developed to describe mercury cycling in Lake Michigan. The model addresses dynamic relationships between net mercury loadings and the resulting concentrations of mercury species in the water and sediment. The simplified predictive modeling fram...

  13. Technical Report: Mercury in the Environment: Implications for Pediatricians

    Microsoft Academic Search

    Lynn R. Goldman; Michael W. Shannon

    Mercury is a ubiquitous environmental toxin that causes a wide range of adverse health effects in humans. Three forms of mercury (elemental, inorganic, and organic) exist, and each has its own profile of toxic- ity. Exposure to mercury typically occurs by inhalation or ingestion. Readily absorbed after its inhalation, mercury can be an indoor air pollutant, for example, after spills

  14. Electronic structure and stability of complex hydrides Mg2 MH x ( M = Fe, Co)

    NASA Astrophysics Data System (ADS)

    Shelyapina, M. G.; Pinyugzhanin, V. M.; Skryabina, N. E.; Hauback, B. C.

    2013-01-01

    This paper reports on the results of theoretical investigations carried out for the hydrides Mg2FeH6 and Mg2CoH5 and the mixed hydride Mg2(FeH6)0.5(CoH5)0.5 in terms of the full-potential linearized augmented plane wave (FLAPW) method. It has been shown that the partial substitution of the Co atoms for the Fe atoms leads to a slight increase in the stability of the hydride, but, at the same time, makes it impossible to increase the stability of the alloy. The high stability of the hydrides under investigation has been explained by the strong bonding between atoms of the transition metal and hydrogen.

  15. Formation and Characterization of Hydride Blisters in Zircaloy-4 Cladding Tubes

    E-print Network

    Paris-Sud XI, Université de

    in a CANDU Zircaloy-2 pressure tube along an array of hydride blisters on the external surface is the material that replaced Zircaloy-2 alloy for pressure tubes in the CANDU reactors. In all these studies

  16. Concerted proton-coupled electron transfer from a metal-hydride complex.

    PubMed

    Bourrez, Marc; Steinmetz, Romain; Ott, Sascha; Gloaguen, Frederic; Hammarström, Leif

    2014-02-01

    Metal hydrides are key intermediates in the catalytic reduction of protons and CO2 as well as in the oxidation of H2. In these reactions, electrons and protons are transferred to or from separate acceptors or donors in bidirectional protoncoupled electron transfer (PCET) steps. The mechanistic interpretation of PCET reactions of metal hydrides has focused on the stepwise transfer of electrons and protons. A concerted transfer may, however, occur with a lower reaction barrier and therefore proceed at higher catalytic rates. Here we investigate the feasibility of such a reaction by studying the oxidation–deprotonation reactions of a tungsten hydride complex. The rate dependence on the driving force for both electron transfer and proton transfer—employing different combinations of oxidants and bases—was used to establish experimentally the concerted, bidirectional PCET of a metal-hydride species. Consideration of the findings presented here in future catalyst designs may lead to more-efficient catalysts. PMID:25615667

  17. Activation of C-H bonds in nitrones leads to iridium hydrides with antitumor activity.

    PubMed

    Song, Xiaoda; Qian, Yong; Ben, Rong; Lu, Xiang; Zhu, Hai-Liang; Chao, Hui; Zhao, Jing

    2013-08-22

    We report the design and synthesis of a series of new cyclometalated iridium hydrides derived from the C-H bond activation of aromatic nitrones and the biological evaluation of these iridium hydrides as antitumor agents. The nitrone ligands are based on the structure of a popular antioxidant, ?-phenyl-N-tert-butylnitrone (PBN). Compared to cisplatin, the iridium hydrides exhibit excellent antitumor activity on HepG2 cells. The metal-coordinated compound with the most potent anticancer activity, 2f, was selected for further analysis because of its ability to induce apoptosis and interact with DNA. During in vitro studies and in vivo efficacy analysis with tumor xenograft models in Institute of Cancer Research (ICR) mice, complex 2f exhibited antitumor activity that was markedly superior to that of cisplatin. Our results suggest, for the first time, that metal hydrides could be a new type of metal-based antitumor agent. PMID:23844605

  18. Hydrogen Internal Combustion Engine Two Wheeler with on-board Metal Hydride Storage

    E-print Network

    Hydrogen Internal Combustion Engine Two Wheeler with on-board Metal Hydride Storage K. Sapru*, S, as a transition, the hydrogen internal combustion engine can lead the way to a hydrogen economy, allowing

  19. Bepi-Colombo Mission to Mercury

    NASA Astrophysics Data System (ADS)

    Hayakawa, Hajime; Maejima, Hironori

    2012-07-01

    BepiColombo has been defined as the ESA-JAXA joint mission to Mercury with the aim to understand the process of planetary formation and evolution in the hottest part of the proto-planetary nebula as well as to understand similarities and differences between the magnetospheres of the Mercury and the Earth. The baseline mission consists of two spacecraft: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The two orbiters will be launched together on one Ariane5. JAXA is responsible for development and operation of MMO while ESA is responsible for development and operation of MPO and Mercury Transfer Module (MTM), launch, cruise phase operation, and Mercury orbit insertion. The main objectives of MPO are to study planet Mercury and planetary formation in the inner solar system. For this purpose, MPO is desgined as a 3-axis stabilized spacecraft and will be placed in a 400 km x 1500 km polar orbit. While the main objectives of MMO are to study Mercury's magnetic field and plasma environment around Mercury. For this purpose, MMO is designed as a spin-stabilized spacecraft and will be placed in a same orbital plane as MPO but has a 400 km x 12000 km. The orbital period of MMO and MPO is designed as 4:1 to achieve cross calibration and cooperative observations. System Critical Design Review (CDR) of MMO has been completed in November 2011 and System CDR for whole BepiColombo mission is scheduled in July 2012. Electrical Interface Check (EIC)/ Mechanical Interface Check (MIC) of MMO FM has been completed in January 2012. MMO Mechanical Test Model is transported to ESA/ESTEC to join Mercury Cruise System (MCS) level Mechianical Test which will be held in this year.

  20. Solvation dynamics and energetics of intramolecular hydride transfer reactions in biomass conversion.

    PubMed

    Mushrif, Samir H; Varghese, Jithin J; Krishnamurthy, Chethana B

    2015-02-21

    Hydride transfer changes the charge structure of the reactant and thus, may induce reorientation/reorganization of solvent molecules. This solvent reorganization may in turn alter the energetics of the reaction. In the present work, we investigate the intramolecular hydride transfer by taking Lewis acid catalyzed glucose to fructose isomerization as an example. The C2-C1 hydride transfer is the rate limiting step in this reaction. Water and methanol are used as solvents and hydride transfer is simulated in the presence of explicit solvent molecules, treated quantum mechanically and at a finite temperature, using Car-Parrinello molecular dynamics (CPMD) and metadynamics. Activation free energy barrier for hydride transfer in methanol is found to be 50 kJ mol(-1) higher than that in water. In contrast, in density functional theory calculations, using an implicit solvent environment, the barriers are almost identical. Analysis of solvent dynamics and electronic polarization along the molecular dynamics trajectory and the results of CPMD-metadynamics simulation of the hydride transfer process in the absence of any solvent suggest that higher barrier in methanol is a result of non-equilibrium solvation. Methanol undergoes electronic polarization during the hydride transfer step. However, its molecular orientational relaxation is a much slower process that takes place after the hydride transfer, over an extended timescale. This results in non-equilibrium solvation. Water, on the other hand, does not undergo significant electronic polarization and thus, has to undergo minimal molecular reorientation to provide near equilibrium solvation to the transition state and an improved equilibrium solvation to the post hydride shift product state. Hence, the hydride transfer step is also observed to be exergonic in water and endergonic in methanol. The aforementioned explanation is juxtaposed to enzyme catalyzed charge transfer reactions, where the enhanced solvation of the transition and product states by enzymes, due to electrostatic interactions, reduces the activation free energy barrier and the free energy change of the reaction. Similarly, we suggest that, in the intramolecular hydride shift, improved solvation of the transition state and of the product state by water is achieved due to minimal polarization and reorientation, and (near) equilibrium solvation. PMID:25591500

  1. Corrosion and hydriding of three zirconium alloys in N-Reactor process tube 0553

    Microsoft Academic Search

    Johnson; A. B. Jr

    1985-01-01

    Coupons of three zirconium alloys - Zircaloy-2 (two lots and three metallurgical conditions); Zircaloy-4; and Zr-2.5Nb - were exposed in N-Reactor pressure tube 0553 for 155 days at 1.2 x 10²° n\\/cm², >1 MeV. Although the exposure was relatively mild, significant differences in hydriding trends were observed for the three alloys. Hydriding rates differed for the three alloys: the rates

  2. Large relativistic effects in molecular properties of the hydride of superheavy element 111

    Microsoft Academic Search

    Michael Seth; Peter Schwerdtfeger; Michael Dolg; Knut Faegri; Bernd A. Hess; Uzi Kaldor

    1996-01-01

    Relativistic and electron correlation contributions in the hydride of the recently discovered superheavy element 111 were studied using ab-initio methods within different relativistic approaches. Relativistic effects decrease the (111)H bond distance by 0.42 Å. As a result of this large bond contraction, the bond distance of (111)H (1.51 Å) is comparable to that of the hydride of its lighter congener

  3. Scaling up effects of Mg hydride in a temperature and pressure-controlled hydrogen storage device

    Microsoft Academic Search

    M. Verga; F. Armanasco; C. Guardamagna; C. Valli; A. Bianchin; F. Agresti; S. Lo Russo; A. Maddalena; G. Principi

    2009-01-01

    A research program addressed to evaluate the magnesium hydride storage scaling up effects is being developed by CESI RICERCA, Milano, and the Hydrogen Group of Padova University. A storage device containing 500g of magnesium hydride powder (manufactured by Venezia Tecnologie S.p.A. using high-energy ball milling) has been designed and tested in different operating conditions. A number of absorption and desorption

  4. Enhancement of heat and mass transfer in metal hydride beds with the addition of Al plates

    Microsoft Academic Search

    Z. Guo

    1999-01-01

    A numerical study is made of transient heat and mass transfer in metal hydride beds in the hydriding process with the addition\\u000a of internal aluminum plates. The two-dimensional equations governing the hydration kinetics, hydrogen flow and heat transfer\\u000a are solved by using the iterative method based on the finite-volume technique. It is found that the heat transfer is enhanced\\u000a by

  5. New binding materials for metal hydride electrodes which permit good recyclability

    Microsoft Academic Search

    T. Hara; N. Yasuda; Y. Takeuchi; T. Sakai; A. Uchiyama; H. Miyamura; N. Kuriyama; H. Ishikawa

    1993-01-01

    Thermoplastic elastomers such as styrene-butadiene-styrene block copolymer (SBS) and styrene-ethylene\\/butylene-styrene block copolymer (SEBS) were used successfully as binding materials for metal hydride (MH) electrodes of a nickel-metal hydride battery. These binding materials have a rubber-like nature and are soluble in organic solvents. It was easy to remove the alloy powder from a used electrode for recycling. The battery performance depended

  6. Electrolyser-metal hydride-fuel cell system for seasonal energy storage

    Microsoft Academic Search

    J. P. Vanhanen; P. D. Lund; J. S. Tolonen

    1998-01-01

    A small-scale seasonal energy storage system, comprising an electrolyser, metal hydride hydrogen store and fuel cell, has been studied. According to the feasibility study, solid polymer electrolysers and fuel cells are the best options for the electrolyser-metal hydride-fuel cell energy storage systems. A round-trip efficiency of 30% has already been demonstrated, and the next target is to reach a round-trip

  7. A variety of electrostatic interactions and adducts can activate NAD(P) cofactors for hydride transfer

    Microsoft Academic Search

    Rob Meijers; Eila Cedergren-Zeppezauer

    2009-01-01

    In NAD(P)-dependent enzymes the coenzyme gives or takes a hydride ion, but how the nicotinamide ring is activated to form the transition state for hydride transfer is not clear. On the basis of ultra-high resolution X-ray crystal structures of liver alcohol dehydrogenase (LADH) in complex with NADH and a number of substrate analogues we proposed that the activation of NADH

  8. A process steam generator based on the high temperature magnesium hydride\\/magnesium heat storage system

    Microsoft Academic Search

    B. Bogdanovi?; A. Ritter; B. Spliethoff; K. Stra?burger

    1995-01-01

    As a first pilot project application of the reversible thermochemical high temperature heat storage system magnesium hydride\\/magnesium a process steam generator has been built and tested. It draws the heat for the generation of superheated steam from a magnesium hydride\\/magnesium (MgH2Mg) heat store and is primarily meant for the storage of high grade industrial waste heat which can be made

  9. Hair mercury concentrations of lactating mothers and breastfed infants in Iran (fish consumption and mercury exposure).

    PubMed

    Okati, Narjes; Sari, Abbas Esmaili; Ghasempouri, Seyed Mahmood

    2012-11-01

    Coastal populations with high seafood consumption in the South Caspian Sea (Iran) have a significant exposure to dietary mercury. This study assesses the biomonitoring of mercury in mothers and breastfed infants in the South Caspian Sea. The mean of mercury concentration in the hair of 93 pairs of mothers and infants was obtained and was 3.55 and 1.89 ?g g(-1), respectively. A statistically significant correlation (R = 0.850, P = 0.000) was seen between mercury concentration in the hair of mothers and infants. The results of this study indicate that hair mercury concentrations exceeded the USEPA reference dose of 1 ?g g(-1) in 82.7 % of mothers and 61.2 % of infants. Also, 31 % of the mothers and 10.7 % of the infants had mercury concentrations more than the WHO "threshold" level (5 ?g g(-1)). The age and fish consumption of mothers were the factors that significantly affected the hair mercury concentration of mothers and infants. Number of dental amalgam fillings of mothers was the factor that only affected mercury in the hair of mothers. According to the results, we can conclude that the main determinant of mercury exposure was the intake of mercury through fish consumption of mothers. PMID:22592844

  10. Estimating mercury emissions from a zinc smelter in relation to China's mercury control policies.

    PubMed

    Wang, S X; Song, J X; Li, G H; Wu, Y; Zhang, L; Wan, Q; Streets, D G; Chin, Conrad K; Hao, J M

    2010-10-01

    Mercury concentrations of flue gas at inlet/outlet of the flue gas cleaning, electrostatic demister, reclaiming tower, acid plant, and mercury contents in zinc concentrate and by-products were measured in a hydrometallurgical zinc smelter. The removal efficiency of flue gas cleaning, electrostatic demister, mercury reclaiming and acid plant was about 17.4%, 30.3%, 87.9% and 97.4% respectively. Flue gas cleaning and electrostatic demister captured 11.7% and 25.3% of the mercury in the zinc concentrate, respectively. The mercury reclaiming tower captured 58.3% of the mercury in the zinc concentrate. About 4.2% of the mercury in the zinc concentrate was captured by the acid plant. Consequently, only 0.8% of the mercury in the zinc concentrate was emitted to the atmosphere. The atmospheric mercury emission factor was 0.5 g t(-1) of zinc produced for the tested smelter, indicating that this process offers the potential to effectively reduce mercury emissions from zinc smelting. PMID:20716469

  11. Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant Pseudomonas putida strain.

    PubMed

    von Canstein, H; Li, Y; Timmis, K N; Deckwer, W D; Wagner-Döbler, I

    1999-12-01

    A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.6 mg/liter and high chloride concentrations (up to 25 g/liter) and had pH values which were either acidic (pH 2.4) or alkaline (pH 13.0). A mercury-resistant bacterial strain, Pseudomonas putida Spi3, was isolated from polluted river sediments. Biofilms of P. putida Spi3 were grown on porous carrier material in laboratory column bioreactors. The bioreactors were continuously fed with sterile synthetic model wastewater or nonsterile, neutralized, aerated chloralkali wastewater. We found that sodium chloride concentrations up to 24 g/liter did not inhibit microbial mercury retention and that mercury concentrations up to 7 mg/liter could be treated with the bacterial biofilm with no loss of activity. When wastewater samples from three different chloralkali plants in Europe were used, levels of mercury retention efficiency between 90 and 98% were obtained. Thus, microbial mercury removal is a potential biological treatment for chloralkali electrolysis wastewater. PMID:10583977

  12. Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant Pseudomonas putida strain

    SciTech Connect

    Canstein, H. von; Li, Y.; Timmis, K.N.; Deckwer, W.D.; Wagner-Doebler, I.

    1999-12-01

    A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.6 mg/liter and high chloride concentrations and had pH values which were either acidic or alkaline. A mercury-resistant bacterial strain, Pseudomonas putida Spi3, was isolated from polluted river sediments. Biofilms of P.putida Spi3 were grown on porous carrier material in laboratory column bioreactors. The bioreactors were continuously fed with sterile synthetic model wastewater or nonsterile, neutralized, aerated chloralkali wastewater. The authors found that sodium chloride concentrations up to 24 g/liter did not inhibit microbial mercury retention and that mercury concentrations up to 7 mg/liter could be treated with the bacterial biofilm with no loss of activity. When wastewater samples from three different chloralkali plants in Europe were used, levels of mercury retention efficiency between 90 and 98% were obtained. Thus, microbial mercury removal is a potential biological treatment for chloralkali electrolysis wastewater.

  13. Mercury in municipal solid wastes and New Jersey mercury prevention and reduction program

    SciTech Connect

    Erdogan, H.; Stevenson, E. [New Jersey Department of Environmental Protection, Trenton, NJ (United States). Division of Science and Research

    1994-12-31

    Mercury is a very toxic heavy metal which accumulates in the brain causing neurological damages involving psychasthenic and vegetative syndrome. At high exposure levels it causes behavioral and personality changes, loss of memory and insomnia. Long-term exposure or exposure during pregnancy to mercury or mercury compounds can permanently damage the kidney and fetus. In addition to potential effects on human health, mercury poisoning can also affect other living organisms. Mercury is different than other heavy metals. It consistently biomagnifies and bioaccumulates within the aquatic food chain. Global sources of mercury release are both natural and anthropogenic. Natural sources include volatilization of gaseous-mercury iron soils ana rocks, volcanic releases, evaporation from the ocean and other water bodies. Anthropogenic sources are fuel and coal combustion, mining, smelting, manufacturing activities, disposal of sludge, pesticides, animal and food waste, and incineration of municipal solid waste. Worldwide combustion of municipal solid waste is the second largest source of atmospheric emission of mercury. In New Jersey, incineration of solid waste is the largest source of atmospheric emission of mercury. The New Jersey Department of Environmental Protection and Energy (NJDEPE) has developed a comprehensive program to control and prevent emission of mercury resulting from combustion municipal solid waste.

  14. Mercury bioremediation by mercury accumulating Enterobacter sp. cells and its alginate immobilized application.

    PubMed

    Sinha, Arvind; Khare, Sunil Kumar

    2012-02-01

    The effective microbial remediation of the mercury necessitates the mercury to be trapped within the cells without being recycled back to the environment. The study describes a mercury bioaccumulating strain of Enterobacter sp., which remediated mercury from the medium simultaneous to its growth. The transmission electron micrographs and electron dispersive X-ray analysis revealed the accumulation of remediated mercury as nano-size particles in the cytoplasm as well as on the cell wall. The Enterobacter sp. in the present work was able to accumulate mercury, without being engineered in its native form. The possibility of recovering the accumulated mercury from the cells is also indicated. The applicability of the alginate immobilized cells in removing mercury from synthetic and complex industrial effluent in a batch mode was amply demonstrated. The initial load of 7.3 mg l(-1) mercury in the industrial effluent was completely removed in 72 h. The cells immobilized in calcium alginate were similarly effective in the complete removal of 5 mg l(-1) HgCl(2) of mercury from the synthetic effluent in less than 72 h. The immobilized cells could be reused for multiple cycles. PMID:21607817

  15. Background levels of atmospheric mercury in Kagoshima City, and influence of mercury emission from Sakurajima Volcano, Southern Kyushu, Japan

    Microsoft Academic Search

    Takashi Tomiyasu; Ayako Nagano; Hayao Sakamoto; Norinobu Yonehara

    2000-01-01

    Vapor phase mercury concentration was determined daily for 1 year (Jan. 1996–Jan. 1997) in order to present the levels of atmospheric mercury in Kagoshima City and to estimate the influence of mercury emission from Sakurajima Volcano, southern Kyushu, Japan. The atmospheric mercury was collected on a porous gold collector at Kagoshima University and was determined by cold vapor atomic absorption

  16. Marine mercury fate: From sources to seafood consumers Mercury in the biosphere has markedly increased over the past

    E-print Network

    Sunderland, Elsie M.

    Editorial Marine mercury fate: From sources to seafood consumers Mercury in the biosphere has provide a synthesis of the science on the sources, fate, and human exposure to mercury (Hg) in marine are the products of two workshops convened by the Coastal and Marine Mercury Ecosystem Research Collaborative (C

  17. Prevalence and antibiotic resistance profile of mercury-resistant oral bacteria from children with and without mercury amalgam fillings

    Microsoft Academic Search

    R. Pike; V. Lucas; P. Stapleton; M. S. Gilthorpe; G. Roberts; R. Rowbury; H. Richards; P. Mullany; M. Wilson

    2002-01-01

    Genes encoding resistance to mercury and to antibiotics are often carried on the same mobile genetic element and so it is possible that mercury-containing dental materials may select for bacteria resistant to mercury and to antibiotics. The main aim of this study was to determine whether the prevalence of Hg-resistant oral bacteria was greater in children with mercury amalgam fillings

  18. Ecosystem Responses to Changed Atmospheric Mercury Load: Results from Seven Years of Mercury Loading to Lake 658

    Microsoft Academic Search

    C. Gilmour; R. Harris; C. Kelly; J. Rudd; M. Amyot; J. Hurley; C. Babiarz; M. Paterson; P. Blanchfield; K. Beaty; K. Sandilands; H. Hintelmann; D. Krabbenhoft; M. Tate; S. Lindberg; G. Southworth; V. St. Louis; J. Graydon

    2009-01-01

    The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments\\/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we are conducting the METAALICUS study, a whole-ecosystem experiment, increasing the mercury load to

  19. First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

    SciTech Connect

    Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

    2013-09-01

    Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

  20. Hydride Formation Process for the Powder Metallurgical Recycle of Zircaloy from Used Nuclear Fuel

    NASA Astrophysics Data System (ADS)

    Parkison, Adam J.; McDeavitt, Sean M.

    2011-01-01

    A Zircaloy recycle process is being investigated based on the underlying principle that Zr reacts with H2 to form ZrH2, which is the same reaction that produces performance limiting ZrH2 formations in reactor cladding. However, in the proposed application, hydride formation is an enabling phenomenon that will embrittle and crumble Zircaloy as a precursor for milling and dehydration to form Zircaloy metal powder. Hydride formation experiments were performed to quantify the primary process variables of time and temperature. These experiments were performed by hydriding nuclear grade Zircaloy-4 tubes under flowing gas (Ar-5 pct H2) for various times and temperatures. The results were used to create a correlation for the formation of zirconium hydride as a function of time and temperature. Further, it was observed that it was much more effective to hydride the Zircaloy-4 tubes at temperatures below the ?- ?- ? eutectoid temperature of 818 K (545 °C), presumably related to the high hydrogen solubility of ?-Zr. Samples treated below this temperature readily crumbled during the hydride formation reaction and were subsequently easily ground to powder, making this the ideal temperature range for the proposed recycle method. Hydrogen pickup was faster above 818 K (545 °C), but the samples were generally tougher.

  1. First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

    NASA Astrophysics Data System (ADS)

    Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

    2013-09-01

    Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

  2. Synthesis, Spectroscopy, and Hydrogen/Deuterium Exchange in High-Spin Iron(II) Hydride Complexes

    PubMed Central

    2015-01-01

    Very few hydride complexes are known in which the metals have a high-spin electronic configuration. We describe the characterization of several high-spin iron(II) hydride/deuteride isotopologues and their exchange reactions with one another and with H2/D2. Though the hydride/deuteride signal is not observable in NMR spectra, the choice of isotope has an influence on the chemical shifts of distant protons in the dimers through the paramagnetic isotope effect on chemical shift. This provides the first way to monitor the exchange of H and D in the bridging positions of these hydride complexes. The rate of exchange depends on the size of the supporting ligand, and this is consistent with the idea that H2/D2 exchange into the hydrides occurs through the dimeric complexes rather than through a transient monomer. The understanding of H/D exchange mechanisms in these high-spin iron hydride complexes may be relevant to postulated nitrogenase mechanisms. PMID:24555749

  3. Analysis of mercury diffusion pumps

    SciTech Connect

    Dunn, K.A.

    1991-01-01

    Several mercury diffusion pump stages in the Tritium Purification process at the Savannah River Site (SRS) have been removed from service for scheduled preventive maintenance. These stages have been examined to determine if failure has occurred. Evidence of fatigue around the flange portion of the pump has been seen. In addition, erosion and cavitation inside the throat of the venturi tube and corrosion on the other surface of the venturi tube has been observed. Several measures are being examined in an attempt to improve the performance of these pumps. These measures, as well as the noted observations, are described. 4 refs.

  4. Analysis of mercury diffusion pumps

    SciTech Connect

    Dunn, K.A.

    1991-12-31

    Several mercury diffusion pump stages in the Tritium Purification process at the Savannah River Site (SRS) have been removed from service for scheduled preventive maintenance. These stages have been examined to determine if failure has occurred. Evidence of fatigue around the flange portion of the pump has been seen. In addition, erosion and cavitation inside the throat of the venturi tube and corrosion on the other surface of the venturi tube has been observed. Several measures are being examined in an attempt to improve the performance of these pumps. These measures, as well as the noted observations, are described. 4 refs.

  5. Film boiling of mercury droplets

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

    1975-01-01

    Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. Diffusion from the upper surface of the drop appears as a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

  6. Geodesy at Mercury with MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria t.; Peale, Stanley J.; Phillips, Roger J.; Solomon, Sean C.

    2006-01-01

    In 2011 the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft will enter Mercury orbit and begin the mapping phase of the mission. As part of its science objectives the MESSENGER mission will determine the shape and gravity field of Mercury. These observations will enable the topography and the crustal thickness to be derived for the planet and will determine the small libration of the planet about its axis, the latter critical to constraining the state of the core. These measurements require very precise positioning of the MESSENGER spacecraft in its eccentric orbit, which has a periapsis altitude as low as 200 km, an apoapsis altitude near 15,000 km, and a closest approach to the surface varying from latitude 60 to about 70 N. The X-band tracking of MESSENGER and the laser altimetry are the primary data that will be used to measure the planetary shape and gravity field. The laser altimeter, which has an expected range of 1000 to 1200 km, is expected to provide significant data only over the northern hemisphere because of MESSENGER's eccentric orbit. For the southern hemisphere, radio occultation measurements obtained as the spacecraft passes behind the planet as seen from Earth and images obtained with the imaging system will be used to provide the long-wavelength shape of the planet. Gravity, derived from the tracking data, will also have greater resolution in the northern hemisphere, but full global models for both topography and gravity will be obtained at low harmonic order and degree. The limiting factor for both gravity and topography is expected to be knowledge of the spacecraft location. Present estimations are that in a combined tracking, altimetry, and occultation solution the spacecraft position uncertainty is likely to be of order 10 m. This accuracy should be adequate for establishing an initial geodetic coordinate system for Mercury that will enable positioning of imaged features on the surface, determination of the planet's obliquity, and detection of the librational motion of the planet about its axis.

  7. Accumulation of mercury in selected plant species grown in soils contaminated with different mercury compounds

    SciTech Connect

    Su, Yi; Han, Fengxiang; Shiyab, Safwan; Chen, Jian; Monts, David L. [Institute for Clean Energy Technology (ICET), Mississippi State University, 205 Research Blvd, Starkville, MS 39759 (United States)

    2007-07-01

    The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl{sub 2}, and Hg(NO{sub 3}){sub 2}, were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (<65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg/kg). Consequently, this plant species may not be suitable for mercury phyto-remediation. Other plant species, such as Indian mustard (Brassica juncea), a well-studied metal accumulator, exhibited severe chlorosis symptoms during some experiments. Among all the plant species studied, Chinese brake fern (Pteris vittata) accumulated significant amount of mercury in both roots and shoots and hence may be considered as a potential candidate for mercury phyto-extraction. During one experiment, Chinese brake ferns accumulated 540 mg/kg and 1469 mg/kg in shoots after 18 days of growing in soils treated with 500 parts-per-million (ppm) and 1000 ppm HgCl{sub 2} powder, respectively; no visual stress symptoms were observed. We also studied mercury phyto-remediation using aged soils that contained HgS, HgCl{sub 2}, or Hg(NO{sub 3}){sub 2}. We have found that up to hundreds of ppm mercury can be accumulated in the roots of Indian mustard plants grown with soil contaminated by mercury sulfide; HgS is assumed to be the most stable and also the predominant mercury form in flood plain soils. We have also started to investigate different mercury uptake mechanisms, such as root uptake of soil contaminant and foliar mercury accumulation from ambient air. We have observed mercury translocation from roots to shoot for Chinese fern and two Indian mustard varieties. (authors)

  8. In vitro effects of mercury-selenium compounds on enzymes.

    PubMed

    Mochizuki, Y; Kobayashi, T; Doi, R

    1982-12-01

    In vitro effects of mercury-selenium compounds, as compared with mercurials, against glucose-6-phosphate dehydrogenase (G6PD), catalase and trypsin were studied. Inhibitory potencies of two mercury-selenium (Hg-Se) compounds, bis(methylmercuric) selenide (BMS), and a reaction product of HgCl2, Na2SeO3 and glutathione (GSH), were markedly weaker than those of their original mercurials, methylmercury and mercuric mercury, respectively. PMID:7167980

  9. Elemental mercury exposure among children of thermometer plant workers

    Microsoft Academic Search

    P. J. Hudson; R. L. Vogt; J. Brondum; L. Witherell; G. Myers; D. C. Paschal

    1987-01-01

    Because evidence of mercury exposure was found among workers of a mercury thermometer-manufacturing plant in March 1984, the Vermont Department of Health studied the workers' children for both exposure to mercury and evidence of mercury toxicity. The median urine mercury level of 23 workers' children was 25 micrograms\\/L. This was significantly higher than the level (5 micrograms\\/L) among 39 children

  10. Mercury removal from aqueous solutions by complexation—ultrafiltration

    Microsoft Academic Search

    J. Barron-Zambrano; S. Laborie; Ph. Viers; M. Rakib; G. Durand

    2002-01-01

    The separation of mercury from aqueous solutions by complexation—ultrafiltration was investigated. Polyethylenimine (PEI) was used as polymeric complexing agent. Effects of pH and chloride ions concentration on mercury retention were studied. Mercury retention depends strongly on both pH and chloride ions concentration. For neutral solutions mercury retention values close to 100% were obtained. A process allowing mercury separation and concentration

  11. Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

    NASA Astrophysics Data System (ADS)

    Patki, Gauri Dilip

    Hydrogen is a promising energy carrier, for use in fuel cells, engines, and turbines for transportation or mobile applications. Hydrogen is desirable as an energy carrier, because its oxidation by air releases substantial energy (thermally or electrochemically) and produces only water as a product. In contrast, hydrocarbon energy carriers inevitably produce CO2, contributing to global warming. While CO2 capture may prove feasible in large stationary applications, implementing it in transportation and mobile applications is a daunting challenge. Thus a zero-emission energy carrier like hydrogen is especially needed in these cases. Use of H2 as an energy carrier also brings new challenges such as safe handling of compressed hydrogen and implementation of new transport, storage, and delivery processes and infrastructure. With current storage technologies, hydrogen's energy per volume is very low compared to other automobile fuels. High density storage of compressed hydrogen requires combinations of high pressure and/or low temperature that are not very practical. An alternative for storage is use of solid light weight hydrogenous material systems which have long durability, good adsorption properties and high activity. Substantial research has been conducted on carbon materials like activated carbon, carbon nanofibers, and carbon nanotubes due to their high theoretical hydrogen capacities. However, the theoretical values have not been achieved, and hydrogen uptake capacities in these materials are below 10 wt. %. In this thesis we investigated the use of silicon for hydrogen generation. Hydrogen generation via water oxidation of silicon had been ignored due to slow reaction kinetics. We hypothesized that the hydrogen generation rate could be improved by using high surface area silicon nanoparticles. Our laser-pyrolysis-produced nanoparticles showed surprisingly rapid hydrogen generation and high hydrogen yield, exceeding the theoretical maximum of two moles of H2 per mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (<100nm diameter) and ball-milled silicon powder (325 mesh). The increase in rate upon decreasing the particle size to 10 nm was even greater than would be expected based upon the increase in surface area. While specific surface area increased by a factor of 6 in going from <100 nm to ˜10 nm particles, the hydrogen production rate increased by a factor of 150. However, in all cases, silicon requires a base (e.g. NaOH, KOH, hydrazine) to catalyze its reaction with water. Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

  12. Structure, chemical bonds and anisotropy in hydrides IMC with CeNi 3 and PuNi 3 structure

    Microsoft Academic Search

    S. A. Lushnikov; V. N. Verbetsky; V. P. Glazkov; V. A. Somenkov

    2007-01-01

    Hydrides of CeNi3, ErNi3 and CeCo3 intermetallic compounds have been synthesised under low and high (up to 200MPa) hydrogen pressure. The structure of the hydrides has been analysed by X-ray and neutron diffraction methods. All hydrides retain the structure of the initial alloys with expanded lattice. The positions and parameters of hydrogen and metallic atoms have been determined and it

  13. Direct, Continuous Hydride Generation Coupled with Microwave Induced Plasma-Atomic Emission Spectrometry for the Determination of Selenium

    Microsoft Academic Search

    Kin C. Ng; Xia-Xiu Xu; Michael J. Brechmann

    1989-01-01

    Selenium is determined by atomic emission technique with microwave induced helium plasma as the excitation source. A continuous hydride generation system using a peristaltic pump, an effective serpentine hydride generator and a gas-liquid separator is developed and interfaced to the He-plasma. The selenium hydride and the reaction by-products are carried directly and continuously by the He carrier gas (0.6 L\\/min)

  14. Method development estimating ambient mercury concentration from monitored mercury wet deposition

    NASA Astrophysics Data System (ADS)

    Chen, S. M.; Qiu, X.; Zhang, L.; Yang, F.; Blanchard, P.

    2013-05-01

    Speciated atmospheric mercury data have recently been monitored at multiple locations in North America; but the spatial coverage is far less than the long-established mercury wet deposition network. The present study describes a first attempt linking ambient concentration with wet deposition using Beta distribution fitting of a ratio estimate. The mean, median, mode, standard deviation, and skewness of the fitted Beta distribution parameters were generated using data collected in 2009 at 11 monitoring stations. Comparing the normalized histogram and the fitted density function, the empirical and fitted Beta distribution of the ratio shows a close fit. The estimated ambient mercury concentration was further partitioned into reactive gaseous mercury and particulate bound mercury using linear regression model developed by Amos et al. (2012). The method presented here can be used to roughly estimate mercury ambient concentration at locations and/or times where such measurement is not available but where wet deposition is monitored.

  15. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies. PMID:25644627

  16. Influence of mercury accumulation on fish

    SciTech Connect

    Dokholyan, V.K.; Akhmedov, A.M.; Akhmedova, T.P.; Shleyfer, G.S.

    1981-01-01

    Questions of the accumulation and distribution of mercury in the organs and tissues of different species of fish were examined in relation to the influence of mercury on survival, physiological and biochemical indices of the blood and brain. In the sturgeon and the roach, mercury accumulated primarily in the kidneys, liver, spleen and gills. The uneven distribution is evidently due to differentiation and differences in the degree of intensity of the metabolic processes of the cells in the organs and tissues, and the physico-chemical mechanism of the interaction of mercury with the biological structure is also important. There are substantial changes in the composition of the blood as a result of intoxication. In the sturgeon and roach a drop is noted in erythrocytes, hemoglobin and leukocytes and qualitative changes in the red blood cells also occur. Deviations were also noted in the correlation of individual forms of leukocytes. These changes are evidently provoked both by the direct presence of mercury in the blood stream and by its disruption of the functions of the hematopoetic organs. Mercury poisoning leads to disruption of the nitrogen metabolism of the brain of the fish. With the accumulation of mercury in fish to a certain critical level, the metabolic processes are inhibited or altered and the defense functions of the blood are weakened. 17 references, 6 figures, 4 tables.

  17. Development of an electromagnetically actuated mercury microvalve

    SciTech Connect

    Adkins, D.R.; Wong, C.C.

    1998-08-01

    The development of microscale fluid handling components has been recognized as a crucial element in the design of microscale chemical detection systems. Recently, work has been undertaken at Sandia National Laboratories to construct a valve that uses a small mercury droplet to control the flow of gas through capillary passages. Electromagnetic forces that are provided by small permanent magnets and a current supply are used to drive the mercury into position. Driving the mercury droplet into a tapered passage halts gas flow through a capillary, while surface tension forces prevent the mercury from passing through the passage. Models have been developed to describe the movement of the mercury droplet and the sealing of the gas passage, and millimeter-scale units have been tested to explore design options. Predictions from the model show that a valve with 10 micron sized features can seal against pressures up to 1.5 atmospheres. Experiments have highlighted the promise of mercury valves and demonstrated problems that can arise from contamination of the mercury.

  18. Mercury's sodium exosphere: Magnetospheric ion recycling

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Delcourt, D.; Johnson, R. E.

    2003-12-01

    A three-dimensional Monte Carlo model of Mercury's neutral sodium exosphere was used to describe correlation between the observed variations in the exospheric density and the variations in the surface concentration of sodium along Mercury's motion around the Sun [Leblanc and Johnson, 2003]. Four processes of ejection were taken into account: thermal and photon stimulated desorptions, solar wind sputtering, and micrometeoroid vaporization. Here a model of ion circulation in Mercury's magnetosphere developed by Delcourt et al. [2002, 2003] is used to examine the contribution from sodium magnetospheric ion recycling. The model is coupled to the exospheric model to track newly ionized sodium formed in Mercury's exosphere. The coupled Na and Na+ model is used to examine the sputtering by and implantation of the reimpacting ions. The magnetospheric ion sputtering does not contribute significantly to the total amount of Na atoms ejected into Mercury's exosphere because of its rather small flux; however, magnetospheric ion implantation in Mercury's surface is sufficiently concentrated inside narrow latitude bands to enhance the local surface concentration of sodium. This enhancement is seen to contribute to the peaks in Mercury's exospheric sodium emission observed at high latitudes when the implanted sodium is exposed to the solar flux near the dayside terminator.

  19. An evaluation of elemental mercury vapor exposure to children due to silver-mercury dental amalgam restorations 

    E-print Network

    Taylor, Ronald Dale

    1989-01-01

    was the Bacharach J. W. Mercury Vapor Sniffer, Model MV-2. This instrument measures the concentration of mercury vapor in air. The ultraviolet photometer detector inside the instrument operates on the principle that energy is absorbed by the mercury molecule... of elemental mercury from dental restorations. The mean mercury vapor concentration in the oral cavity of test subjects exceeded the recommended 24-hour ambient air exposure level of 0. 015 mg Hg/m . A regression analysis of the data resulted...

  20. Observations of Mercury's magnetic field

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1975-01-01

    Magnetic field data obtained by Mariner 10 during the third and final encounter with the planet Mercury on 16 March 1975 were studied. A well developed bow shock and modest magnetosphere, previously observed at first encounter on 29 March 1974, were again observed. In addition, a much stronger magnetic field near closest approach, 400 gamma versus 98 gamma, was observed at an altitude of 327 km and approximately 70 deg north Mercurian latitude. Spherical harmonic analysis of the data provide an estimate of the centered planetary magnetic dipole of 4.7 x 10 to the 22nd power Gauss/cu cm with the axis tilted 12 deg to the rotation axis and in the same sense as Earth's. The interplanetary field was sufficiently different between first and third encounters that in addition to the very large field magnitude observed, it argues strongly against a complex induction process generating the observed planetary field. While a possibility exists that Mercury possesses a remanent field due to magnetization early in its formation, a present day active dynamo seems to be a more likely candidate for its origin.

  1. Polygonal impact craters on mercury

    NASA Astrophysics Data System (ADS)

    Weihs, G. T.; Leitner, J. J.; Firneis, M. G.

    2015-06-01

    The existence of polygonal impact craters (PICs) on Mercury is confirmed by this study, which was performed by analyzing 291 named impact craters greater than 12 km in diameter, photographed by the spacecraft Mariner 10 and MESSENGER. All 15 quadrangles of Mercury were scanned for polygonal impact craters with at least two straight rim segments. A resulting total number of 33 PICs out of the 291 named impact craters is in accordance with the expectation of 10-15% out of all impact craters. Calculations were performed on the number of PICs per quadrangle, on the distribution of polygonal impact craters on the surface, on the distribution of diameters, on the mean values of diameters, and the values of the angles between straight rims and the results plotted. The distribution of PICs per quadrangle does not follow any pattern, but is roughly proportional to the number of impact craters. The diameter range of the PICs lies between 65 and 240 km, on average the value is about 120 km. Some topics need further studies - the lack of small PICs, the interrelations of PICs and geological environments, and the irregular distribution of PICs on the surface showing large empty areas.

  2. The magnetic field of Mercury

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1977-01-01

    The Mariner 10 spacecraft encountered Mercury three times in 1974-1975. The first and third encounters provided detailed observations of a well-developed detached bow shock wave which results from the interaction of the solar wind. The planet possesses a global magnetic field and a modest magnetosphere, which deflects the solar wind. The field is approximately dipolar, with orientation in the same sense as earth, tilted 12 deg from the rotation axis. The magnetic moment corresponds to an undistorted equatorial field intensity of 350 gammas, approximately 1% of earth's. The field, while unequivocally intrinsic to the planet, may be due to remanent magnetization acquired from an extinct dynamo or a primordial magnetic field or due to a presently active dynamo. The latter possibility appears more plausible at present. In any case, the existence of the magnetic field provides very strong evidence of a mature differentiated planetary interior with a large core (core radius about 0.7 Mercury radius) and a record of the history of planetary formation in the magnetization of the crustal rocks.

  3. [Mercury in the environs of Kagoshima Bay].

    PubMed

    Ando, T; Yanagihashi, T; Tomari, T; Wakisaka, I

    1992-02-01

    Mercury contents of samples of sea water and fish from Kagoshima Bay, sediments in rivers, and the surface soil from the area surrounding a waste incinerator in the city of Kagoshima were measured to search for the source of mercury in Kagoshima Bay. The results obtained were as follows: 1) Mercury contents of sea water samples at 26 stations in Kagoshima Bay ranged from 6.3 to 19.7 ng/l. When the 26 stations were classified into four areas, the entrance, the middle and the interior of the Bay, and the water around the Sakurajima area, mercury contents of the samples from the last area were significantly higher than either at the entrance or in the interior of the Bay. 2) Mercury contents in the cardinal fish, Apogon notatus, were significantly higher than those in either the dragonet, Callionymus lunatus, or the sillaginoid, Sillago japonica. Mercury contents of fish from the Ushine coast station, the innermost part of the Bay, were significantly higher than those from the other collecting stations. Moreover, significantly interactions between the species of fish and the sampling stations were detected, and mercury contents of cardinal fish from Ushine coast station were 6.7-fold higher than those from the sampling station at the mouth of the Shinkawa river. 3) River sediments obtained 1 km from the mouth of each river contained from 4 to 96 micrograms/kg of mercury. Mercury contents of the river sediments from the Wada river were higher than those from the other rivers examined.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1556832

  4. Removal of mercury from soil with earthworms

    SciTech Connect

    Dorfman, D. [Monmouth Coll., West Long Branch, NJ (United States)

    1994-12-31

    Earthworms can live in soils containing high quantities of mercury, lead, and zinc. The worms (Lumbricus terrestris) concentrate these heavy metals in their tissues. The use of these worms to reduce the quantities of mercury and other heavy metals in soils may be practical. In July, 1993, a preliminary study was made using earthworms and soils with differing amounts of mercury, The quantities were 0.0 grams, 0.5 grams, and 1.0 grams of mercury as mercuric chloride. Earthworms were placed into these soils for two or more weeks, then harvested. The worms were rinsed with deionized water, then dissolved in nitric acid. Each sample was prepared for analysis with the addition of HNO{sub 3}, H{sub 2}SO{sub 4}, potassium permanganate, and hydrozylamine hydrochloride. A Jerome Instrument gold foil analyzer was used to determine levels of mercury after volatilizing the sample with stannous chloride. Worms exposed to contaminated soils remove 50 to 1,400 times as much mercury as do worms in control soils. In a hypothetical case, a site contaminated with one pound of mercury, 1,000 to 45,000 worms would be required to reduce mercury levels to background levels in the soil (about 250 ppb). After harvesting worms in contaminated soil they could be dried (90% of their weight is water), and the mercury regained by chemical processes. Soil conducive to earthworm survival is required. This includes a well aerated loamy soil, proper pH (7.0), and periodic watering and feeding. There are several methods of harvesting worms, including flooding and electricity. Large numbers of worms can be obtained from commercial growers.

  5. Fish mercury distribution in Massachusetts, USA lakes

    SciTech Connect

    Rose, J.; Hutcheson, M.S.; West, C.R.; Pancorbo, O.; Hulme, K.; Cooperman, A.; DeCesare, G.; Isaac, R.; Screpetis, A.

    1999-07-01

    The sediment, water, and three species of fish from 24 of Massachusetts' (relatively) least-impacted water bodies were sampled to determine the patterns of variation in edible tissue mercury concentrations and the relationships of these patterns to characteristics of the water, sediment, and water bodies (lake, wetland, and watershed areas). Sampling was apportioned among three different ecological subregions and among lakes of differing trophic status. The authors sought to partition the variance to discover if these broadly defined concepts are suitable predictors of mercury levels in fish. Average muscle mercury concentrations were 0.15 mg/kg wet weight in the bottom-feeding brown bullheads (Ameriurus nebulosus); 0.31 mg/kg in the omnivorous yellow perch (Perca flavescens); and 0.39 mg/kg in the predaceous largemouth bass (Micropterus salmoides). Statistically significant differences in fish mercury concentrations between ecological subregions in Massachusetts, USA, existed only in yellow perch. The productivity level of the lakes (as deduced from Carlson's Trophic Status Index) was not a strong predictor of tissue mercury concentrations in any species. pH was a highly (inversely) correlated environmental variable with yellow perch and brown bullhead tissue mercury. Largemouth bass tissue mercury concentrations were most highly correlated with the weight of the fish (+), lake size (+), and source area sizes (+). Properties of individual lakes appear more important for determining fish tissue mercury concentrations than do small-scale ecoregional differences. Species that show major mercury variation with size or trophic level may not be good choices for use in evaluating the importance of environmental variables.

  6. Observation of Mercury’s sodium tail using Fabry–Perot Interferometer

    Microsoft Academic Search

    S. Kameda; M. Kagitani; S. Okano; I. Yoshikawa; J. Ono

    2008-01-01

    We observed sodium emission from Mercury’s atmosphere using a Fabry–Perot Interferometer at Haleakala Observatory on June 14, 2006. The Fabry–Perot Interferometer was used as a wavelength-tunable filter. The spectra of the surface reflection were subtracted from the observed spectra because sodium emission is contaminated by the surface reflection of Mercury. The image obtained in our observation shows the sodium exosphere

  7. Mercury capture into biogenic amorphous selenium nanospheres produced by mercury resistant Shewanella putrefaciens 200.

    PubMed

    Jiang, Shenghua; Ho, Cuong Tu; Lee, Ji-Hoon; Duong, Hieu Van; Han, Seunghee; Hur, Hor-Gil

    2012-05-01

    Shewanella putrefaciens 200, resistant to high concentration of Hg(II), was selected for co-removal of mercury and selenium from aqueous medium. Biogenic Hg(0) reduced from Hg(II) by S. putrefaciens 200 was captured into extracellular amorphous selenium nanospheres, resulting in the formation of stable HgSe nanoparticles. This bacterial reduction could be a new strategy for mercury removal from aquatic environments without secondary pollution of mercury methylation or Hg(0) volatilization. PMID:22386108

  8. The tropical African mercury anomaly: lower than expected mercury concentrations in fish and human hair.

    PubMed

    Black, Frank J; Bokhutlo, Thethela; Somoxa, Aaron; Maethamako, Mothusi; Modisaemang, Ontlogetse; Kemosedile, Thebe; Cobb-Adams, Cristina; Mosepele, Ketlhatlogile; Chimbari, Moses

    2011-04-15

    Mercury is a neurotoxin and global pollutant, and wetlands and newly flooded areas are known to be sites of enhanced production of monomethylmercury, the form of mercury that is readily biomagnified in aquatic food chains to potentially toxic levels. The Okavango Delta in Botswana, Southern Africa, is the largest inland delta in the world and a wetland ecosystem that experiences dramatic annual flooding of large tracts of seasonal floodplains. The Delta was, therefore, expected to be home to high mercury levels in fish and to be an area where local subsistence fishing communities would be at substantial risk of mercury toxicity from fish consumption. Total mercury concentrations measured in 27 species of fish from the Okavango Delta averaged (mean±s.d., wet weight) 19±19ng g(-1) in non-piscivorous fish, and 59±53ng g(-1) in piscivorous fish. These mercury concentrations are similar to those reported for fish from lakes in other areas of tropical Africa, demonstrating that not all wetlands are sites of elevated mercury concentrations in biota. Even more intriguing is that concentrations of mercury in fish from across tropical Africa are systematically and substantially lower than those typically reported for fish from freshwater ecosystems elsewhere globally. The reasons for this apparent "African mercury anomaly" are unclear, but this finding poses a unique opportunity to improve our understanding of mercury's biogeochemical cycling in the environment. Mercury concentrations measured in human hair collected in subsistence fishing communities in the Okavango Delta were similarly low (0.21±0.22?g g(-1) dry weight) despite high levels of fish consumption, and reflect the low mercury concentrations in the fish here. PMID:21342703

  9. Evaluation of Mercury in Urine as an Indicator of Exposure to Low Levels of Mercury Vapor

    Microsoft Academic Search

    Joyce S. Tsuji; Pamela R. D. Williams; Melanie R. Edwards; Krishna P. Allamneni; Michael A. Kelsh; Dennis J. Paustenbach; Patrick J. Sheehan

    2002-01-01

    We conducted a pooled analysis to investigate the relationship between exposure to elemental mercury in air and resulting urinary mercury levels, specifically at lower air levels relevant for envi- ronmental exposures and public health goals (i.e., < 50 µg\\/m3 down to 1.0 µg\\/m3). Ten studies reporting paired air and urine mercury data (149 samples total) met criteria for data quality

  10. Phase Transition of Rare-earth Metal Hydrides under High Pressure

    NASA Astrophysics Data System (ADS)

    Kim, Duck

    2013-06-01

    Hydrogen is the lightest and smallest element in the periodic table. Despite its most simple electronic structure, enormous complexity can arise when hydrogen participates in the formation of solids. High pressure perturbs the free energy sufficiently to push the system into unexplored regions of the energy landscape, thus providing an excellent platform for the investigation of novel physics in hydrides such as metal-insulator transition, superconductivity as well as stoichiometric change. In this talk, I will overview recent progress on hydrides research under pressure in both theoretical works and experiments. Theoretical predictions on atomic positions and stoichiometry in hydrides under high pressure play a critical role to determine crystal structures of experimentally observed novel compounds, especially due to tiny scattering length of hydrogen atoms in solids. In addition, predicted physical property such as metallization and superconductivity in hydrides can guide experiments and experimental observations provide inputs for refinement of calculations I will show examples to highlight the importance of integrated experiment-theory collaboration to study rare-earth hydride under high-pressure. Hydrogen is the lightest and smallest element in the periodic table. Despite its most simple electronic structure, enormous complexity can arise when hydrogen participates in the formation of solids. High pressure perturbs the free energy sufficiently to push the system into unexplored regions of the energy landscape, thus providing an excellent platform for the investigation of novel physics in hydrides such as metal-insulator transition, superconductivity as well as stoichiometric change. In this talk, I will overview recent progress on hydrides research under pressure in both theoretical works and experiments. Theoretical predictions on atomic positions and stoichiometry in hydrides under high pressure play a critical role to determine crystal structures of experimentally observed novel compounds, especially due to tiny scattering length of hydrogen atoms in solids. In addition, predicted physical property such as metallization and superconductivity in hydrides can guide experiments and experimental observations provide inputs for refinement of calculations I will show examples to highlight the importance of integrated experiment-theory collaboration to study rare-earth hydride under high-pressure. Energy Frontier Research in Extreme Environments (EFREE) Center.

  11. Bepi-Colombo mission to Mercury

    NASA Astrophysics Data System (ADS)

    Hayakawa, Hajime; Benkhoff, Johannes; Fujimoto, Masaki; Van Casteren, Jan

    BepiColombo is a ESA-JAXA joint mission to Mercury with the aim to understand the process of planetary formation and evolution as well as to understand similarities and differences between the magnetospheres of Mercury and Earth. The baseline mission consists of two spacecraft, i.e. the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The two orbiters and Mercury Transfer Module (MTM) are conbined into stack configuration. The stack configuration is nemed Mercury Cruise System (MCS). JAXA is responsible for the development and operation of MMO, while ESA is responsible for the development and operation of MPO as well as the launch, cruise, and the insertion of two spacecraft into their dedicated orbits. The main objectives of MMO are to study Mercury’s magnetic field and plasma environment around Mercury while the main objectives of MPO are to study Mercury itself. MMO is designed as a spin-stabilized spacecraft to be placed in a 600 km x 11,800 km polar orbit. The spacecraft will accommodate instruments mostly dedicated to in-situ measurement near Mercury. MPO is designed as 3-axis stabilized spacecraft to be placed in a 400km x 1,500km polar orbit. The spacecraft will accommodate instruments mainly dedicated to remote sensing measurement. CDR for MMO was finished in 2011. Spacecraft CDR for ESA modules was finished in Nov. 2013. Mission CDR is expected in this summer. Each modules of BepiColombo is now in standalone Final AIV phase. Final AIV for MMO is expected to be finished in this autumn while final AIV for MPO and MTM is expected to be finished in early next year. MMO will be transported to ESA/ESTEC in early next year and join final AIV for MCS. After MCS final AIV, The BepiColombo is scheduled to be launched in July 2016 by an Ariane-5 and arrive at Mercury in January 2022. In this paper, we will report the latest information of BepiColombo project.

  12. Mariner Venus/Mercury 1973 navigation strategy

    NASA Technical Reports Server (NTRS)

    Mckinley, E. L.; Jones, J. B.; Bantell, M. H.

    1973-01-01

    This paper presents the navigational aspects of the Mariner Venus/Mercury 1973 mission. Principal emphasis is on the development of the trajectory correction strategy, propellant costs, and delivery accuracies at Venus and Mercury. Key error sources and mission constraints are discussed. Of particular interest are the statistics of the first, post-Venus, maneuver which must correct for the magnification of errors in the Venus encounter. Finally, although not a primary objective of the mission, the analysis is extended to include a second Mercury encounter.

  13. Sulfurization of a carbon surface for vapor phase mercury removal II: Sulfur forms and mercury uptake

    E-print Network

    Borguet, Eric

    ; Surface properties 1. Introduction Mercury is a hazardous air pollutant that has attracted significant scrubbers, spray dryer adsorption (SDA), and activated carbon injection [2]. Among technologies mentioned

  14. Mercury exposures and symptoms in smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China.

    PubMed

    Li, Ping; Feng, Xinbin; Qiu, Guangle; Li, Zhonggen; Fu, Xuewu; Sakamoto, Minishi; Liu, Xiaojie; Wang, Dingyong

    2008-05-01

    Mercury exposures to smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China were evaluated by urine and hair mercury survey. The mean urinary mercury (U-Hg), hair total mercury (T-Hg), and hair methyl mercury (Me-Hg) for smelting workers was 1060 microg/g creatinine (microg/g Cr), 69.3 and 2.32 microg/g, respectively. The results were significantly higher than that of control group, which is 1.30 microg/g Cr, 0.78 and 0.65 microg/g, correspondingly. The average urinary beta2-microglobulin (beta2-MG) was 248 microg/g Cr for the exposed group contrasting to 73.5 microg/g Cr for the control group and the data showed a serious adverse effect on renal system for the smelting workers. The workers were exposed to mercury vapor through inhalation, and the exposure route of Me-Hg may be through intake of polluted diet. The results indicate that age, alcohol drinking, and smoking are not crucial factors controlling the urine and hair mercury levels for the exposed and the control group. Clinical symptoms including finger and eyelid tremor, gingivitis, and typical dark-line on gums were observed in six workers. This study indicated that the smelting workers in Wuchuan were seriously exposed to mercury vapor. PMID:17897640

  15. Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

    2014-11-01

    Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury ‘nano-trap’ as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury ‘nano-trap’ exhibits a record-high saturation mercury uptake capacity of over 1,000?mg?g?1, and can effectively reduce the mercury(II) concentration from 10?p.p.m. to the extremely low level of smaller than 0.4?p.p.b. well below the acceptable limits in drinking water standards (2?p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation.

  16. Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution.

    PubMed

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

    2014-01-01

    Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury 'nano-trap' as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury 'nano-trap' exhibits a record-high saturation mercury uptake capacity of over 1,000?mg?g(-1), and can effectively reduce the mercury(II) concentration from 10?p.p.m. to the extremely low level of smaller than 0.4?p.p.b. well below the acceptable limits in drinking water standards (2?p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation. PMID:25410491

  17. DESCRIPTION AND EVALUATION OF ATMOSPHERIC MERCURY SIMULATION USING THE CMAQ MODEL

    EPA Science Inventory

    The Community Multiscale Air Quality (CMAQ) modeling system has recently been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury in three distinct forms; elemental mercury gas, reactive gaseous mercury, and particulate mercury. Emis...

  18. MERCURY REDUCTION IN PRODUCTS AND PROCESSES: A REVIEW OF THE ELECTRICAL AND ELECTRONIC INDUSTRIES

    EPA Science Inventory

    The electrical and electronics industries have significantly reduced the amount of mercury from various products and processes. However, the unique electromechanical and photoelectronic properties of mercury and mercury compounds have made replacement of mercury difficult in some...

  19. MERCURY REDUCTION IN PRODUCTS AND PROCESSES: A REVIEW OF THE ELECTRICAL AND ELECTRONIC INDUSTRIES

    EPA Science Inventory

    The electrical and electronics industries have significantly reduced the amount of mercury from various products and processes. owever, the unique electromechanical and photoelectronic properties of mercury and mercury compounds have made replacement of mercury difficult in some ...

  20. Synthesis and characterization of metal hydride electrodes. Interim report

    SciTech Connect

    McBreen, J.; Reilly, J.J.

    1995-10-01

    The objective of this project is to elucidate the compositional and structural parameters that affect the thermodynamics, kinetics and stability of alloy hydride electrodes and to use this information in the development of new high capacity long life hydride electrodes for rechargeable batteries. The work focuses on the development of AB{sub 5} alloys and the application of in situ methods, at NSLS, such as x-ray absorption (XAS), to elucidate the role of the alloying elements in hydrogen storage and corrosion inhibition. The most significant results to date are: The decay of electrode capacity on cycling was directly related to alloy corrosion. The rate of corrosion depended in part on both the alloy composition and the partial molar volume of hydrogen, V{sub H}. The corrosion rate depended on the composition of the A component in AB{sub 5} (LaNi{sub 5} type) alloys. Partial substitution of La with Ce in AB{sub 5} alloys substantially inhibits electrode corrosion on cycling. Recent results indicate that Co also greatly inhibits electrode corrosion, possibly by minimizing V{sub H}. The AB{sub 5} alloys investigated included LaNi{sub 5}, ternary alloys (e.g. LaN{sub 4.8}Sn{sub 0.2} and La{sub 0.8}Ce{sub 0.2}Ni{sub 5}), alloys with various substitutions for both La and Ni (e.g. La{sub 0.8}Ce{sub 0.2}Ni{sub 4.8}Sn{sub 0.2}) and mischmetal (Mm) alloys of the type normally used in batteries, such as MmB{sub 5} (B = Ni{sub 3.55}Mn{sub 0.4}A1{sub 0.3}Co{sub 0.75}). A major effort was devoted to the effects of La substitution in the A component. Both in situ and ex situ XAS measurements are used to study the electronic effects that occur on the addition of various metal substitutions and on the ingress of hydrogen.