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1

Analysis of total mercury in human tissues prepared by microwave decomposition using a hydride generator system coupled to an atomic absorption spectrometer  

Microsoft Academic Search

A fast and efficient procedure has been developed for the analysis of total mercury in human tissues and blood using a hydride vapor generator system coupled to an atomic absorption spectrometer (HVG–AA). Tissue and blood samples were digested in a pressurized microwave decomposition system and the digest diluted prior to formation of free mercury vapor and analysis by atomic absorption.

Xenophon Cominos; Sotiris Athanaselis; Artemis Dona; Antonios Koutselinis

2001-01-01

2

Mercury  

SciTech Connect

Papers are presented on future observations of and missions to Mercury, the photometry and polarimetry of Mercury, the surface composition of Mercury from reflectance spectrophotometry, the Goldstone radar observations of Mercury, the radar observations of Mercury, the stratigraphy and geologic history of Mercury, the geomorphology of impact craters on Mercury, and the cratering record on Mercury and the origin of impacting objects. Consideration is also given to the tectonics of Mercury, the tectonic history of Mercury, Mercury's thermal history and the generation of its magnetic field, the rotational dynamics of Mercury and the state of its core, Mercury's magnetic field and interior, the magnetosphere of Mercury, and the Mercury atmosphere. Other papers are on the present bounds on the bulk composition of Mercury and the implications for planetary formation processes, the building stones of the planets, the origin and composition of Mercury, the formation of Mercury from planetesimals, and theoretical considerations on the strange density of Mercury.

Vilas, F.; Chapman, C.R.; Matthews, M.S.

1988-01-01

3

Validation of a hydride generation atomic absorption spectrometry methodology for determination of mercury in fish designed for application in the Brazilian national residue control plan.  

PubMed

In the present study, a method for the determination of mercury (Hg) in fish was validated according to ISO/IEC 17025, INMETRO (Brazil), and more recent European recommendations (Commission Decision 2007/333/EC and 2002/657/EC) for implementation in the Brazilian Residue Control Plan (NRCP) in routine applications. The parameters evaluated in the validation were investigated in detail. The results obtained for limit of detection and quantification were respectively, 2.36 and 7.88 ?g kg(-1) of Hg. While the recovery varies between 90-96%. The coefficient of variation was of 4.06-8.94% for the repeatability. Furthermore, a comparison using an external proficiency testing scheme was realized. The results of method validated for the determination of the mercury in fish by Hydride generation atomic absorption spectrometry were considered suitable for implementation in routine analysis. PMID:24007488

Damin, Isabel C F; Santo, Maria A E; Hennigen, Rosmari; Vargas, Denise M

2013-01-01

4

Mercury  

MedlinePLUS

... of the lungs Medication to remove mercury and heavy metals from the body INORGANIC MERCURY For inorganic mercury ... McGraw Hill; 2008:chap 365. Baum CR. Mercury: Heavy metals and inorganic agents. In: Shannon MW, Borron SW, ...

5

Mercury  

MedlinePLUS

... Releases and Spills Fish Consumption Advisories Consumer Products Mercury News December 2012. EPA Finalizes Clean Air Standards ... if one is requested. Learn more Ban on Mercury Exports will begin January 1, 2013 By federal ...

6

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.

7

Mercury  

Microsoft Academic Search

Mercury may provide answers to questions regarding the formation and evolution of our Solar System. This article reviews what\\u000a is known about Mercury from the Mariner 10 flybys of 1974 and 1975 and from thirty years of ground-based telescopic observations\\u000a with ever improving instrumentation. Many new discoveries, such as possible water ice at Mercury’s polar regions, make the\\u000a anticipation of

Robert G. Strom; Ann L. Sprague

8

Hydriding process  

DOEpatents

BS>A method is described for hydriding a body of a Group IV-B metal, preferably zirconium, to produce a crack-free metal-hydride bedy of high hydrogen content by cooling the body at the beta to beta + delta boundary, without further addition of hydrogen, to precipitate a fine-grained delta-phase metal hydride in the beta + delta phase region and then resuming the hydriding, preferably preceded by a reheating step. (Official Gazette)

Raymond, J.W.; Taketani, H.

1973-12-01

9

Mercury  

Microsoft Academic Search

New findings on the environmental fate of Hg indicate that lakes can be contaminated by long distance transport on mercury vapor in the atmosphere and that higher levels of Me Hg in fish are associated with acidification of lakes and with the creation of hydroelectric reservoirs. Considerable progress has been made in the understanding of the disposition and metabolism of

Thomes W. Clarkson

1989-01-01

10

Mercury  

NSDL National Science Digital Library

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Mercury. These data include planet size, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, and albedo. Images of the planet include general surface features such as crater basins, the Caloris Basin, and other images taken by the Mariner 10 spacecraft.

11

Hydride compositions  

DOEpatents

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 hydrogen 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 hydrogen and then heating at a temperature below the softening temperature of any of the. constituents so that their chemical and structural integrity is preserved. When the composition is used to store hydrogen, its hydrogen content can be found simply by measuring P.sub.H.sbsb.2 and determining H/M from the isothermic function of the composition.

Lee, Myung W. (North Augusta, SC)

1995-01-01

12

Hydride compositions  

DOEpatents

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.

Lee, Myung, W.

1994-01-01

13

Volatile hydride and methyl compounds of selected elements formed in the marine environment  

Microsoft Academic Search

This review selectively describes volatile compounds of phosphorus, arsenic, sulfur, selenium, tin, lead and mercury in the marine environment with an emphasis on mercury. The discussion includes formation of volatile hydride, methyl, and mixed methyl\\/hydride compounds by biotic, abiotic, and mixed biotic\\/abiotic paths. The review also describes stabilities of the volatile compounds to water and oxygen, their environmental concentrations, and

James H. Weber

1999-01-01

14

Determination of mercury and selenium in herbal medicines and hair by using a nanometer TiO2-coated quartz tube atomizer and hydride generation atomic absorption spectrometry.  

PubMed

The nanometer TiO(2) particle was coated onto the inner wall of a T-shaped quartz tube atomizer (QTA) and then was used as a new atomizer (NT-QTA) for the determination of Hg and Se by hydride generation atomic absorption spectrometry (HGAAS). After coating 67.4 mg TiO(2) on a quartz tube, the analytical performance of NT-QTA-HGAAS was compared to conventional QTA-HGAAS and it was improved as follows: (a) the linear range of the calibration curves was expanded from 10.0-80.0 ng mL(-1) to 5.0-150.0 ng mL(-1) for Hg, and from 10.0-70.0 ng mL(-1) to 5.0-100.0 ng mL(-1) for Se; (b) the characteristic concentration of was decreased from 2.8 ng mL(-1)/1% to 1.1 ng mL(-1)/1% for Hg and from 1.2 ng mL(-1)/1% to 0.8 ng mL(-1)/1% for Se; and (c) the interference from the coexistence of As on the determination of Hg and Se could be eliminated. The achieved technique was applied for the determination of Hg and Se in herbal medicines and hair. PMID:21388738

Li, Shun-Xing; Zheng, Feng-Ying; Cai, Shu-Jie; Cai, Tian-Shou

2011-02-15

15

Hydride compressor  

DOEpatents

Method of producing high energy pressurized gas working fluid power from a low energy, low temperature heat source, wherein the compression energy is gained by using the low energy heat source to desorb hydrogen gas from a metal hydride bed and the desorbed hydrogen for producing power is recycled to the bed, where it is re-adsorbed, with the recycling being powered by the low energy heat source. In one embodiment, the adsorption-desorption cycle provides a chemical compressor that is powered by the low energy heat source, and the compressor is connected to a regenerative gas turbine having a high energy, high temperature heat source with the recycling being powered by the low energy heat source.

Powell, James R. (Wading River, NY); Salzano, Francis J. (Patchogue, NY)

1978-01-01

16

Silica Embedded Metal Hydrides  

SciTech Connect

A method to produce silica embedded metal hydride was developed. The product is a composite in which metal hydride particles are embedded in a matrix of silica. The silica matrix is highly porous. Hydrogen gas can easily reach the embedded metal hydride particles. The pores are small so that the metal hydride particles cannot leave the matrix. The porous matrix also protects the metal hydride particles from larger and reactive molecules such as oxygen, since the larger gas molecules cannot pass through the small pores easily. Tests show that granules of this composite can absorb hydrogen readily and withstand many cycles without making fines.

Heung, L.K. [Westinghouse Savannah River Company, AIKEN, SC (United States); Wicks, G.G.

1998-08-01

17

Metal hydride technology  

SciTech Connect

A promising alternative for hydrogen storage is storage as a metal hydride. The properties and applications of those systems which have proven or potential utility as hydrogen storage compounds are summarized. Specific systems discussed are magnesium alloy hydrides, iron-titanium alloys, titanium-chromium alloys, and rare earth alloys. (LK)

Reilly, J.J.

1979-02-01

18

Metal hydride heat pump  

SciTech Connect

A metal hydride heat pump is disclosed comprising a first and a second heat medium receptacle having heat media flowing therein and a plurality of closed vessels each containing a hydrogen gas atmosphere and divided into a first chamber having a first metal hydride filled therein and a second chamber having a second metal hydride filled therein. The first and second chambers of each closed vessel are made to communicate with each other so that hydrogen gas passes from one chamber to the other but the metal hydrides do not, and a group of the first chambers of the closed vessels being located within the first heat medium receptacle and a group of the second chambers of the closed vessels being located within the second heat medium receptacle, whereby heat exchange is carried out between the heat media in the first and second heat medium receptacles and the first and second metal hydrides through the external walls of the closed vessels.

Nishizaki, T.; Miyamoto, K.; Miyamoto, M.; Nakata, Y.; Yamaji, K.; Yoshida, K.

1983-12-27

19

Chemistry of intermetallic hydrides  

SciTech Connect

Certain intermetallic hydrides are safe, convenient and inexpensive hydrogen storage compounds. A particular advantage of such compounds is the ease with which their properties can be modified by small changes in alloy composition or preparation. This quality can be exploited to optimize their storage properties for particular applications, e.g. as intermetallic hydride electrodes in batteries. We will be concerned herein with the more important aspects of the thermodynamic and structural principles which regulate the behavior of intermetallic hydrogen systems and then illustrate their application using the archetype hydrides of LaNi5, FeTi and Mg alloys. The practical utility of these classes of materials will be briefly noted.

Reilly, J.J.

1991-01-01

20

Millimeter-Wave Spectroscopy of Ethylmercury Hydride  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

21

Boron Hydride Polymer Coated Substrates.  

National Technical Information Service (NTIS)

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 i...

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

1986-01-01

22

Hydrated hydride anion clusters.  

PubMed

On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion hydrated by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed. PMID:17979342

Lee, Han Myoung; Kim, Dongwook; Singh, N Jiten; Ko?aski, Maciej; Kim, Kwang S

2007-10-28

23

Boron hydride polymer coated substrates  

DOEpatents

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.

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

1987-01-01

24

Boron hydride polymer coated substrates  

DOEpatents

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.

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

1986-08-27

25

Spectrum of Nickel Hydride  

Microsoft Academic Search

RECENTLY we have observed the spectrum obtained by introducing nickel carbonyl vapour into the flame of a Meker burner. Just above the blue-green cones, in the hottest part of the flame, we find a very wide-spaced band structure which can only be attributed to a hydride.

A. G. Gaydon; R. W. B. Pearse

1934-01-01

26

Mercury Quest  

NSDL National Science Digital Library

In this module, students pretend they have been hired as an environmental consulting firm to deliver testimony for the hearing to develop a mercury pollution reduction plan for the State. In order to accomplish this task their consulting company must: inventory and assess current sources of mercury pollution to the extent feasible, including both (fictitious) Ramford County and regional sources of mercury pollution; review the current science on mercury deposition, transport, and exposure pathways; review the current science on the impacts of mercury pollution on public health and ecosystems; review existing mercury pollution policies in other states and in the US; and review strategies for clean up and reduction of exposure to mercury.

27

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

28

Hydride Formation in Zirconium Alloys  

NASA Astrophysics Data System (ADS)

The ingress of hydrogen during corrosion in service can degrade the mechanical properties of zirconium alloy nuclear fuel cladding because of the formation of brittle hydrides. The formation of these hydrides is reviewed in light of recent synchrotron radiation experimental results and phase-field modeling computational results that provide new insight on the process.

Motta, Arthur T.; Chen, Long-Qing

2012-12-01

29

Hydrogen storage in metal hydrides  

SciTech Connect

The storage of hydrogen as a metal hydride is discussed. Properties of some representative hydrogen-storage mediums (MgH/sub 2/, Mg/sub 2/NiH/sub 4/, VH/sub 2/, FeTiH/sub 1/ /sub 95/, LaNi/sub 5/H/sub 7/, liquid hydrogen, and gaseous hydrogen) are compared. Magnesium hydride, the more promising of the two binary hydrides, is thought to be only a borderline possibility as a hydrogen-storage medium at present. Of the three ternary hydrides listed the leading contender is iron-titanium hydride. It's main advantage over lanthanum-pentanickel hydride is one of cost. All the metal hydrides listed have a higher hydrogen storage capacity than an equal volume of liquid or gaseous hydrogen has. Energy densities (watt-hours per kilogram) of various automotive power sources either already in existence or proposed are tabulated. Metal hydrides lag far behind gasoline in terms of energy density, but they are competitive with electric batteries in this respect.

Reilly, J.J.; Sandrock, G.D.

1980-02-01

30

Dimensionally stable metallic hydride composition  

DOEpatents

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.

Heung, Leung K. (Aiken, SC)

1994-01-01

31

SFRSF: Mercury  

NSDL National Science Digital Library

This South Florida Restoration Science Forum page discusses the problem with mercury in restoring habitats and ecosystems in southern Florida. This study looks at the origin of mercury in the water and atmosphere, and how Everglades restoration will affect mercury risks. Managing water quality and quantity to reduce risks, and understanding the food web to determine entry points and biomagnification are also discussed. Locations where mercury toxicity is above the healthy limit are identified. There are links for more information provided.

32

Development of metal hydride composites  

SciTech Connect

Most of current hydride technology at Savannah River Site is based on beds of metal hydride powders; the expansion upon hydridation and the cycling results in continued breakdown into finer particles. Goal is to develop a composite which will contain the fines in a dimensionally stable matrix, for use in processes which require a stable gas flow through a hydride bed. Metal hydride composites would benefit the advanced Thermal Cycling Absorption process (hydrogen isotope separation), and the Replacement Tritium Facility (storage, pumping, compression, purification of hydrogen isotopes). These composites were fabricated by cold compaction of a mixture of metal hydride granules and coarse copper powder; the porosity in the granules was introduced by means of ammonium carbonate. The composite pellets were cycled 138 times in hydrogen with the loss of LANA0.75 (LaNi{sub 4.25}Al{sub 0.75}) limited to the surface. Vacuum sintering can provide additional strength at the edges. Without a coating, the metal hydride particles exposed at the pellet surface can be removed by cycling several times in hydrogen.

Congdon, J.W.

1992-12-01

33

Mercury and Selenium Content in Selected Seafood  

Microsoft Academic Search

The mercury and selenium contents of fresh seafood were determined, respectively, by means of cold vapor atomic absorption spectroscopy (CVAAS) and hydride-generation atomic absorption spectrometry (HGAAS). All the values obtained were lower than the European Union's legal limit of 0.5 mg\\/kg fresh food, rising to 1.0 mg\\/kg for the edible parts of some listed species; in fish they vary between

Maria Plessi; Davide Bertelli; Agar Monzani

2001-01-01

34

Thermophysical properties of zirconium hydride and uranium–zirconium hydride  

Microsoft Academic Search

Thermal diffusivities of ?-phase Zirconium hydrides (ZrH1.69–2.00) were measured in the temperature range from 300 to 600 K by means of a laser-flash method. The thermal diffusivity of ?-phase Zr hydrides increased with increasing hydrogen concentration and decreased with increasing temperature. The thermal diffusivities of ?-phase ZrHx with x>1.83 were larger than that of ?-phase Zr. The experimental data on

B. Tsuchiya; J. Huang; K. Konashi; M. Teshigawara; M. Yamawaki

2001-01-01

35

Erbium hydride decomposition kinetics.  

SciTech Connect

Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

Ferrizz, Robert Matthew

2006-11-01

36

Metal hydride-air battery  

Microsoft Academic Search

Portable metal-hydride fueled fuel cell systems, producing regulated 28VDC output at 30 watts and 60 watts, have been built. The systems are easily refuelable with pellets of solid sodium aluminum hydride and water to generate hydrogen. Ambient air, supplied by natural convection, is the oxidant. The energy density approaches 960 watt-hours per pound of fuel. A power conditioning unit provides

M. Onischak; B. S. Baker

1975-01-01

37

Low density metal hydride foams  

DOEpatents

Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powdered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam. 6 figs.

Maienschein, J.L.; Barry, P.E.

1990-01-01

38

Low density metal hydride foams  

DOEpatents

Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powdered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam. 6 figs.

Maienschein, J.L.; Barry, P.E.

1990-12-31

39

Physics of hydride fueled PWR  

NASA Astrophysics Data System (ADS)

The first part of the work presents the neutronic results of a detailed and comprehensive study of the feasibility of using hydride fuel in pressurized water reactors (PWR). The primary hydride fuel examined is U-ZrH1.6 having 45w/o uranium: two acceptable design approaches were identified: (1) use of erbium as a burnable poison; (2) replacement of a fraction of the ZrH1.6 by thorium hydride along with addition of some IFBA. The replacement of 25 v/o of ZrH 1.6 by ThH2 along with use of IFBA was identified as the preferred design approach as it gives a slight cycle length gain whereas use of erbium burnable poison results in a cycle length penalty. The feasibility of a single recycling plutonium in PWR in the form of U-PuH2-ZrH1.6 has also been assessed. This fuel was found superior to MOX in terms of the TRU fractional transmutation---53% for U-PuH2-ZrH1.6 versus 29% for MOX---and proliferation resistance. A thorough investigation of physics characteristics of hydride fuels has been performed to understand the reasons of the trends in the reactivity coefficients. The second part of this work assessed the feasibility of multi-recycling plutonium in PWR using hydride fuel. It was found that the fertile-free hydride fuel PuH2-ZrH1.6, enables multi-recycling of Pu in PWR an unlimited number of times. This unique feature of hydride fuels is due to the incorporation of a significant fraction of the hydrogen moderator in the fuel, thereby mitigating the effect of spectrum hardening due to coolant voiding accidents. An equivalent oxide fuel PuO2-ZrO2 was investigated as well and found to enable up to 10 recycles. The feasibility of recycling Pu and all the TRU using hydride fuels were investigated as well. It was found that hydride fuels allow recycling of Pu+Np at least 6 times. If it was desired to recycle all the TRU in PWR using hydrides, the number of possible recycles is limited to 3; the limit is imposed by positive large void reactivity feedback.

Ganda, Francesco

40

Computational Modeling of Uranium Hydriding and Complexes  

Microsoft Academic Search

Uranium hydriding is one of the most important processes that has received considerable attention over many years. Although many experimental and modeling studies have been carried out concerning thermochemistry, diffusion kinetics and mechanisms of U-hydriding, very little is known about the electronic structure and electronic features that govern the U-hydriding process. Yet it is the electronic feature that controls the

K. Balasubramanian; Wigbert J. Siekhaus; William McLean

2003-01-01

41

Method of producing a chemical hydride  

DOEpatents

A method of producing a chemical hydride is described and which includes selecting a composition having chemical bonds and which is capable of forming a chemical hydride; providing a source of a hydrocarbon; and reacting the composition with the source of the hydrocarbon to generate a chemical hydride.

Klingler, Kerry M. (Idaho Falls, ID); Zollinger, William T. (Idaho Falls, ID); Wilding, Bruce M. (Idaho Falls, ID); Bingham, Dennis N. (Idaho Falls, ID); Wendt, Kraig M. (Idaho Falls, ID)

2007-11-13

42

Mercury: Health Effects  

MedlinePLUS

... toxicological profile for mercury . Top of page Elemental mercury effects Elemental (metallic) mercury primarily causes health effects ... 0370.htm . Top of page Effects of other mercury compounds (inorganic and organic) High exposures to inorganic ...

43

Feasibility of developing a mercury hydride molecular laser  

SciTech Connect

The formation and deexcitation of the A/sup 2/Pi/sub 1//sub ///sub 2/ and X/sup 2/summation/sub 1//sub ///sub 2/ states of the HgH molecule in a dense Hg--H/sub 2/--He (N/sub 2/, CO) rf discharge plasma was studied for the first time. The luminescence of the HgH molecule was studied as a function of the plasma density and composition, the absorption of radiation from the highest-intensity HgH bands and quenching of the first electronically excited A/sup 2/Pi/sub 1//sub ///sub 2/ (v = 0,1) and A/sup 2/Pi/sub 3//sub ///sub 2/ (v = 0) states were measured, and strong HgH luminescence was achieved in the discharge. An analysis of the results showed that chemical reactions involving the formation of HgH* (A) take place in a dense plasma at a fast rate without the involvement of HgH(X) and deexcitation of this state by CO molecules. It is concluded that this kinetic model of an HgH laser is valid.

Kolbycheva, P.D.; Kolbychev, G.V.

1985-12-01

44

49 CFR 173.311 - Metal hydride storage systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Metal hydride storage systems. 173.311 Section 173...Packaging § 173.311 Metal hydride storage systems. The following packing instruction...applicable to transportable UN Metal hydride storage systems (UN3468) with pressure...

2011-10-01

45

Radon hydrides: structure and bonding.  

PubMed

Quantum chemical calculations, using gradient-correct density functional at the BP86 level in conjunction with TZ2P basis sets, have been carried out for the radon hydrides HRnY (with Y = F, Cl, Br, I, CCH, CN, and NC). The bonding in HRnY is studied using different bond ruptures, establishing the role of those stabilizing (and destabilizing) factors that prevent these species to be dissociated. Although all HRnY systems studied here are bound equilibrium structures, they are metastable species with respect to the HRnY ? Rn + HY decomposition channel. However, the HRnY ? H + Rn + Y reaction is endothermic. So, these results indicate the possibility to identify the radon hydrides in noble-gas matrices. PMID:21088784

Juarez, Rosalba; Zavala-Oseguera, Claudia; Jimenez-Halla, J Oscar C; Bickelhaupt, F Matthias; Merino, Gabriel

2010-11-19

46

Isotope Effect in Dissociation of Uranium Hydride  

Microsoft Academic Search

Isotope effect on dissociation behavior of uranium hydride has been studied. The equilibrium dissociation pressure of uranium protide(UH3), deuteride (UD3), and of equimolar mixture of both hydrides are measured. The dissociation pressure of deuteride is higher than that of the protide by a factor of about 2 at 400°C and mixed hydride of UH3 and UD3 has intermediate dissociation pressures.

Tetsuo TANABE; Satoshi MIURA; Sh?suke IMOTO

1979-01-01

47

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

Microsoft Academic Search

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

Yoshihisa Tahra; Tomohiko IWASKI; Kenji KONASKI

2010-01-01

48

HVEM in situ hydriding of hydrogen storage materials  

Microsoft Academic Search

The microstructural changes induced during hydriding have been investigated by high-voltage electron microscopy and in situ hydriding studies. Hydriding generates high dislocation densities, which has implications for the mechanism involved in the hydride transformation and possible effects of prior hydrogen exposures on subsequent hydriding behavior. In situ hydriding of LaCoâ and LaNiâCoâ has been demonstrated. There appears to be an

E. A. Kenik; J. Mullins; S. Spooner; B. R. Livesay

1979-01-01

49

Lightweight hydrides for automotive storage of hydrogen  

NASA Astrophysics Data System (ADS)

The primary objectives of the considered investigations are related to the reduction of the dissociation temperature of lightweight materials, and the development of new lightweight hydrides containing little, if any, critical material. Attention is given to the characteristics of metal hydrides, the characteristics of a magnesium-base alloy which is to be employed in hydrogen storage systems for automobiles, aspects of alloy development, and the evaluation of magnesium hydride alloys with the aid of a hydride cycling rig. New information concerning the effect of cycling on magnesium alloys is discussed.

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

50

Mercury in Schools  

NSDL National Science Digital Library

This site explains the importance of mercury as a school and community issue and helps to identify where it is most likely to be found. There is information about online graduate courses for teachers on the environmental and health impacts of mercury; a Powerpoint presentation on mercury in schools; a mercury I.Q. test; and a mercury curriculum. The Taking Action section focuses on pollution prevention, spills and safety, mercury related legislation and school collection programs. There are also links to the U.S. Environmental Protection Agency mercury programs and information on fish consumption advisories, mercury spill incident case studies, mercury collection programs and agency contact information for specific regions.

51

Mercury in Schools  

Microsoft Academic Search

Mercury can be found in schools in many places. Liquid mercury may be used in science labs and experiments. Science classes may use thermometers, barometers or other devices that contain mercury. School nurses may have mercury thermometers or blood pressure gauges. Thermostats and light switches in the building may contain mercury. Fluorescent light bulbs are commonly used in schools. These

Kimberly B. Henken; Jorge Atiles

52

Mercury's Messenger  

ERIC Educational Resources Information Center

|Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

Chapman, Clark R.

2004-01-01

53

Mercury Calculator  

NSDL National Science Digital Library

This interactive calculator produced by Teachers' Domain helps you determine the mercury levels in various types of fish, and enables you to make more informed choices about which fish are safe to eat and which should be avoided or eaten infrequently.

Foundation, Wgbh E.

2010-12-23

54

Hydrogen storage technology for metal hydrides  

SciTech Connect

The advantages of using hydrogen as a secondary energy carrier are stated, and numerous factors pertinent to the technology of hydrogen storage via metal hydrides are briefly described. The technology is centered on iron-titanium hydride, FeTiH/sub x/, as the most practical choice for the safe and compact storage of hydrogen. Uses of hydride hydrogen as a fuel or energy carrier are given. The features of hydride reservoir designs are explained, and some performance data are given for two reservoirs constructed at BNL. Results of tests on the long-term behavior of FeTiH/sub x/ are presented along with information on pressure drop in a hydride bed. Two methods of accommodating hydride expansion are described. Other topics include: container materials selection, safety testing of FeTiH/sub x/, hydride materials development, storage systems work at BNL, the proposed Hydrogen-Halogen Energy Storage System, a proposed technique of storing hydrogen in hollow glass microspheres at very high pressure, and information on the commercial availability of materials and equipment for hydride hydrogen. Current development needs are included in the various sections.

Strickland, G

1978-06-01

55

DUAL SITE CATALYSTS FOR HYDRIDE MANIPULATION  

Microsoft Academic Search

This comment describes our efforts to develop dual site catalysts for hydride manipulation. We began by analyzing the mechanism of alcohol oxidation with the ruthenium-based Shvo catalyst, which utilizes a proton transfer to template a hydride transfer from carbon to ruthenium in a single transition state. In our project we are working to extend this concept of reactivity from the

Brian L. Conley; Travis J. Williams

2011-01-01

56

Inhibited Solid Propellant Composition Containing Beryllium Hydride.  

National Technical Information Service (NTIS)

An object of this invention is to provide a composition of beryllium hydride and carboxy-terminated polybutadiene which is stable. Another object of this invention is to provide a method for inhibiting the reactivity of beryllium hydride toward carboxy-te...

W. W. Thompson

1978-01-01

57

Erbium hydride thermal desorption : controlling kinetics.  

SciTech Connect

Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report show that hydride film processing parameters directly impact thermal stability. Issues to be addressed include desorption kinetics for dihydrides and trihydrides, and the effect of film growth parameters, loading parameters, and substrate selection on desorption kinetics.

Ferrizz, Robert Matthew

2007-08-01

58

Preparation and catalytic properties of cerium hydride  

Microsoft Academic Search

Cerium hydride was formed at a moderate temperature (523K) and atmospheric pressure using a pulse-flow technique. Its adsorption and catalytic properties were probed using deuterium, oxygen, carbon monoxide, carbon dioxide, methanol, and propyne. Deuterium exchange with the hydrogen of the hydride was examined and not all of the hydrogen was found to be exchangeable. It is likely that this was

S. David Jackson; Gordon J. Kelly; Elaine M. Vass

2008-01-01

59

Positron Annihilation in Rare-Earth Hydrides  

Microsoft Academic Search

Analysis of the angular correlations of positron-annihilation radiation from erbium, gadolinium, holmium, and ytterbium hydrides indicates that the electronic structure of these materials is basically metallic in nature. As was previously found in the case of cerium hydride, the angular correlations were found to be broader than those from their parent metals by amounts which were consistent with the assumption

M. P. CHOUINARDt; D. R. Gustafson

1971-01-01

60

Hydrogenation using hydrides and acid  

DOEpatents

The present invention relates to a very rapid, non-catalytic process for hydrogenating unsaturated organic compounds that can be carried out at temperatures generally lower than previously utilized. In this process organic compounds which contain at least one reducible functional group are hydrogenated non-catalytically by reacting them with a hydride complex and a strong acid. The reducible functional group may be, for example, C=C, C-OH, C-O-C, or a strained cyclic structure. If the reactants are not mutually soluble, they are dissolved in an appropriate inert solvent. 3 tabs.

Bullock, R.M.

1989-12-13

61

Zirconium hydride containing explosive composition  

DOEpatents

An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising a non-explosive compound or mixture of non-explosive compounds which when subjected to an energy fluence of 1000 calories/cm.sup.2 or less is capable of releasing free radicals each having a molecular weight between 1 and 120. Exemplary donor additives are dibasic acids, polyamines and metal hydrides.

Walker, Franklin E. (18 Shadow Oak Rd., Danville, CA 94526); Wasley, Richard J. (4290 Colgate Way, Livermore, CA 94550)

1981-01-01

62

Activated aluminum hydride hydrogen storage compositions and uses thereof  

SciTech Connect

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.

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

2010-11-23

63

Mercury's MESSENGER  

NSDL National Science Digital Library

A salient feature of our species is the impetus to explore. Now that most of our own planet is well explored, the Space Age has opened the heavens for our excursions. One of the most challenging space exploration missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury. This article outlines the scientists' current knowledge of the innermost planet and describes the MESSENGER spacecraft and mission.

Chapman, Clark R.

2004-03-01

64

Liquid suspensions of reversible metal hydrides  

DOEpatents

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.

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

1983-12-08

65

Surface catalyzed mercury transformation reactions  

Microsoft Academic Search

Mercury is a known pollutant that has detrimental effect on human health and environment. The anthropogenic emissions of mercury account for 10 to 30% of worldwide mercury emissions. There is a need to control\\/reduce anthropogenic mercury emissions. Many mercury control technologies are available but their effectiveness is dependent on the chemical form of mercury, because different chemical forms of mercury

Patanjali Varanasi

2009-01-01

66

Computational Modeling of Uranium Hydriding and Complexes  

SciTech Connect

Uranium hydriding is one of the most important processes that has received considerable attention over many years. Although many experimental and modeling studies have been carried out concerning thermochemistry, diffusion kinetics and mechanisms of U-hydriding, very little is known about the electronic structure and electronic features that govern the U-hydriding process. Yet it is the electronic feature that controls the activation barrier and thus the rate of hydriding. Moreover the role of impurities and the role of the product UH{sub 3} on hydriding rating are not fully understood. An early study by Condon and Larson concerns with the kinetics of U-hydrogen system and a mathematical model for the U-hydriding process. They proposed that diffusion in the reactant phase by hydrogen before nucleation to form hydride phase and that the reaction is first order for hydriding and zero order for dehydriding. Condon has also calculated and measures the reaction rates of U-hydriding and proposed a diffusion model for the U-hydriding. This model was found to be in excellent agreement with the experimental reaction rates. From the slopes of the Arrhenius plot the activation energy was calculated as 6.35 kcal/mole. In a subsequent study Kirkpatrick formulated a close-form for approximate solution to Condon's equation. Bloch and Mintz have proposed the kinetics and mechanism for the U-H reaction over a wide range of pressures and temperatures. They have discussed their results through two models, one, which considers hydrogen diffusion through a protective UH{sub 3} product layer, and the second where hydride growth occurs at the hydride-metal interface. These authors obtained two-dimensional fits of experimental data to the pressure-temperature reactions. Kirkpatrick and Condon have obtained a linear solution to hydriding of uranium. These authors showed that the calculated reaction rates compared quite well with the experimental data at a hydrogen pressure of 1 atm. Powell et al. have studied U-hydriding in ultrahigh vacuum and obtained the linear rate data over a wide range of temperatures and pressures. They found reversible hydrogen sorption on the UH{sub 3} reaction product from kinetic effects at 21 C. This demonstrates restarting of the hydriding process in the presence of UH{sub 3} reaction product. DeMint and Leckey have shown that Si impurities dramatically accelerate the U-hydriding rates. We report our recent results of relativistic computations that vary from complete active space multi-configuration interaction (CAS-MCSCF) followed by multi-reference configuration interaction (MRSDCI) computations that included up to 50 million configurations for modeling of uranium-hydriding with cluster models will be presented.

Balasubramanian, K; Siekhaus, W J; McLean, W

2003-02-03

67

Mercury and health care  

PubMed Central

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.

Rustagi, Neeti; Singh, Ritesh

2010-01-01

68

Mercury and health care.  

PubMed

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

Rustagi, Neeti; Singh, Ritesh

2010-08-01

69

A Metal Hydride Mobile Air Conditioning System  

Microsoft Academic Search

This paper describes the development of an electrical compressor-driven air conditioning system for automotive applications. The system uses the thermal properties of reversible metal hydride alloys, which are retained within advanced-design hydride heat exchangers. Calculations on system performance predict high energy efficiency in a package of competitive size and cost. A proof-of-principle prototype has been constructed and bench tested. Measurements

Daniela Magnetto; Stefano Mola; Centro Ricerche Fiat; David H. DaCosta; Mark Golben; Matthew Rosso

70

Mercury Quick Facts: Health Effects of Mercury Exposure  

MedlinePLUS

How much mercury spilled in a room will make air in the room unsafe? Any amount of mercury spilled indoors can ... in a small bedroom. EPA cleaning up a mercury spill at a house. What is Elemental Mercury? ...

71

Synthesis, high-resolution millimeter-wave spectroscopy, and ab initio calculations of ethylmercury hydride.  

PubMed

The millimeter-wave rotational spectrum of an organomercury compound, ethylmercury hydride, has been recorded and assigned for the first time. 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 accurate quartic centrifugal distortion constants related to this type of compound. Estimations of the nuclear quadrupole coupling constants have less predictive power than those of the structural parameters, but are good enough to satisfy the spectroscopic needs. In addition, the orientation of the axis of the H-Hg-C bonds 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 as the product of the chemical reaction described here, and its calculated equilibrium geometry is confirmed. PMID:22587478

Goubet, Manuel; Motiyenko, Roman A; Margulès, Laurent; Guillemin, Jean-Claude

2012-05-23

72

Mercury Study Report to Congress. Volume 5. Health Effects of Mercury and Mercury Compounds.  

National Technical Information Service (NTIS)

This volume summarizes the available information on human health effects and animal data for hazard identification and dose-response assessment for three forms of mercury: elemental mercury, mercury chloride (inorganic mercury), and methylmercury (organic...

B. Hassett-Sipple J. Swartout R. Schoeny

1997-01-01

73

Mercury Contamination of Aquatic Ecosystems  

NSDL National Science Digital Library

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.

Krabbenhoft, D. P.; Rickert, D. A.

74

Thin-film metal hydrides.  

PubMed

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

Remhof, Arndt; Borgschulte, Andreas

2008-12-01

75

Global trends in mercury management.  

PubMed

The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

Kim, Dae-Seon; Choi, Kyunghee

2012-11-29

76

Global Trends in Mercury Management  

PubMed Central

The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health.

Choi, Kyunghee

2012-01-01

77

Automotive Storage of Hydrogen Using Modified Magnesium Hydrides.  

National Technical Information Service (NTIS)

Metal hydrides can store more hydrogen per unit volume than normal high pressure or cryogenic techniques. Little energy is required to store the hydrogen in the hydride, and high stability at room temperature assures low losses over long storage periods. ...

D. A. Rohy J. F. Nachman T. E. Duffy

1975-01-01

78

Mercury study report to Congress. Volume 5. Health effects of mercury and mercury compounds  

Microsoft Academic Search

This volume summarizes the available information on human health effects and animal data for hazard identification and dose-response assessment for three forms of mercury: elemental mercury, mercury chloride (inorganic mercury), and methylmercury (organic mercury). Effects are summarized by endpoint. The risk assessment evaluates carcinogenicity, mutagenicity, developmental toxicity and general systemic toxicity of these chemical species of mercury. Toxicokinetics (absorption, distribution,

B. Hassett-Sipple; J. Swartout; R. Schoeny

1997-01-01

79

Hydride-containing molten salts and their technology implications  

Microsoft Academic Search

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

Bor Y. Liaw

1993-01-01

80

The Case Against Mercury.  

National Technical Information Service (NTIS)

The presentation discusses mercury in the environment. It reviews its toxicity and a few poisoning cases. Primarily it looks at the events and findings which led to the recent enforcement actions to control mercury release.

R. B. Dean

1972-01-01

81

Preventing Mercury Pollution.  

ERIC Educational Resources Information Center

|Discusses mercury pollution as a source of many of today's school closings and provides insight for developing a spill response plan as well as hints for reducing mercury pollution occurrences. (GR)|

Manicone, Santo

2001-01-01

82

Mercury CEM Calibration.  

National Technical Information Service (NTIS)

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 workin...

J. F. Rovani J. F. Schabron S. S. Sorini

2007-01-01

83

Kinetics of hydrogen desorption from the powders of metal hydrides  

Microsoft Academic Search

Desorption of hydrogen from the powders of metal hydrides (MH) is affected by several interplaying processes including hydrogen desorption from and recombination on the metal surface, diffusion within the bulk metal and different hydride phases, and decomposition of the hydride phase. In present work, possible mechanisms of hydrogen release from the MH are proposed and discussed. Analytical models are developed

I. E. Gabis; A. P. Voit; E. A. Evard; Yu. V. Zaika; I. A. Chernov; V. A. Yartys

2005-01-01

84

A RATIONALIZATION OF THE FORMATION OF SALINE AND METALLIC HYDRIDES  

Microsoft Academic Search

These two parts were issued separately, but are cataloged as a unit. ; The previously reported observation that internuclear distances in metallic ; hydrides are approximately the sum of the cation radius and hydride anion radius ; (l.29A) is extended, and additional data presented. If it is assumed that the ; lattice energy of a metallic hydride is similar to

Gibb; T. R. P. Jr

1958-01-01

85

HYDRIDE-RELATED DEGRADATION OF SNF CLADDING UNDER REPOSITORY CONDITIONS  

Microsoft Academic Search

The purpose and scope of this analysis\\/model report is to analyze the degradation of commercial spent nuclear fuel (CSNF) cladding under repository conditions by the hydride-related metallurgical processes, such as delayed hydride cracking (DHC), hydride reorientation and hydrogen embrittlement, thereby providing a better understanding of the degradation process and clarifying which aspects of the process are known and which need

K. McCoy

2000-01-01

86

49 CFR 173.311 - Metal hydride storage systems.  

Code of Federal Regulations, 2012 CFR

...173.311 Metal hydride storage systems. The following...transportable UN Metal hydride storage systems (UN3468) with pressure...150 liters (40 gallons) in water capacity and having a maximum...exceeding 25 MPa. Metal hydride storage systems must be...

2012-10-01

87

Mercury and Neptune  

NSDL National Science Digital Library

In this project you will learn about the solar system and how Mercury and Neptune are alike and different. How are the planets, Mercury and Neptune, alike and different? Use your Venn Diagram to write how Mercury and Neptune are different in the outer circles and how the planets are alike where the circles overlap. Begin by reviewing the Solar System. Notice where Mercury and Neptune are compared to the ...

Simpson, Ms.

2009-10-21

88

Understanding Mercury, Understanding Autism  

Microsoft Academic Search

Our current research on mercury has focused on its interactions with the immune system. We have found that mercury interferes with the signaling be tween glial cells and neurons in the developing bra in, resulting in defects in neuronal migration. This in terference involves the same pathways that mercury can affect in the immune system, including modulation of cytokines and

Ellen Silbergeld; Jennifer Nyland

89

Mercury's sodium exosphere  

Microsoft Academic Search

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

F. Leblanc; R. E. Johnson

2003-01-01

90

Dental amalgam and mercury  

SciTech Connect

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.

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

1991-08-01

91

Dental amalgam and mercury  

Microsoft Academic Search

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

Mackert; J. R. Jr

1991-01-01

92

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...

93

Peru Mercury Inventory 2006.  

National Technical Information Service (NTIS)

In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has lo...

E. Sandoval H. Howard M. A. Yepez W. E. Brooks

2007-01-01

94

Hydride Transfer from Rhodium Complexes to Triethylborane  

SciTech Connect

The hydrides HRh(depe)2 and HRh(dmpe)2 (depe = Et2PCH2CH2PEt2, dmpe = Me2PCH2CH2PMe2) have thermodynamic hydride donor abilities comparable to LiHBEt3, as indicated by their ability to transfer a hydride ligand to Et3B. These hydrides can be generated from hydrogen gas in the presence of a strong base such as potassium t-butoxide or lithium diisopropylamide. This reaction proceeds through the oxidative addition of hydrogen to form the [H2Rh(diphosphine)2](CF3SO3) complexes, followed by deprotonation. The oxidative addition of H2 is favored by diphosphine ligands with electron donating substituents and large chelate bites. In the present study, the driving force for oxidative addition of H2 follows the order [Rh(dmpe)2](CF3SO3) > [Rh(depe)2](CF3SO3) > [Rh(dppe)2](CF3SO3) with [Rh(dmpe)2](CF3SO3) binding H2 more strongly than [Rh(dppe)2](CF3SO3) (dppe = Ph2PCH2CH2PPh2) by at least 2.7 kcal/mol. The effect of the chelate bite size is larger. [H2Rh(depx)2](CF3SO3) (depx = 1,2-(Et2PCH2)2C6H4) binds H2 more strongly than [Rh(depe)2](CF3SO3) by 12 kcal/mol. An understanding of both hydrogen activation and hydride donor abilities is important for developing powerful hydride donors from H2. Acknowledgment: This research was supported by the Director’s Discretionary Research and Development Program of the National Renewable Energy Laboratory, and in part, by the Chemical Sciences Program of the Office of Basic Energy Sciences of the Department of Energy. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

DuBois, Daniel L.; Blake, D. M.; Miedaner, Alex; Curtis, Calvin J.; DuBois, Mary R.; Franz, James A.; Linehan, John C.

2006-08-28

95

Scope on Skies: Mercury  

NSDL National Science Digital Library

This month, Mercury will start becoming visible over the western horizon shortly after sunset. If you have students observe Mercury, they should do so at approximately the same time for each observation. During the first half of the month, Mercury will appear higher above the horizon and set a bit later each day. Students can also note that Mercury appears brighter following superior conjunction than when it is close to inferior conjunction. Despite its greater distance following superior conjunction, Mercury will be in nearly a full phase and will reflect more sunlight and appear brighter than when it is closer to us, but as a thin crescent.

Riddle, Bob

2008-01-01

96

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

DOEpatents

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##

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

97

Haloaluminum Hydrides and Deuterides. Ditetrahydrofuran Adducts.  

National Technical Information Service (NTIS)

Tetrahydrofuran adducts of haloaluminum hydrides, A1HyX3-y.z(THF) (X = C1, Br, I), and some deuterated analogs were prepared and characterized. The adducts are crystalline solids which are normally isolated as stoichiometric ditetrahydrofuranates. Cryosco...

D. L. Schmidt E. E. Flagg

1966-01-01

98

Metal hydride fuel storage and method thereof  

DOEpatents

Disclosed herein is a metal hydride fuel storage cartridge having integrated resistive heaters that can be used in conjunction with fuel cells such as MEMS-based fuel cells. The cartridge is fabricated using micromachining methods and thin/thick film materials synthesis techniques.

Morse, Jeffrey D [Martinez, CA; Jankowski, Alan F [Livermore, CA; Yu, Conrad [Antioch, CA

2009-05-05

99

Metal hydrides for hydrogen isotope separation  

SciTech Connect

A new continuous chromatographic technique has been developed to separate hydrogen isotopes using metal hydrides. Separation factors are calculated based on the statistical mechanics. A computer simulation has been developed for the process using the results of the separation factors. 11 refs., 5 figs.

Lee, M.W.

1988-01-01

100

Method for Preparation of Uranium Hydride.  

National Technical Information Service (NTIS)

A method for preparation of uranium hydride starting from hydrogen and uranium is described. In the temperature range of 250 deg up to 350 deg C, and pressures above 10 torr, hydrogen reacts smoothly with uranium turnings forming a fine black or dark gray...

M. S. Gorski M. Goncalves A. Mirage W. Lima

1985-01-01

101

Magnetic Properties of Beta-Uranium Hydride  

Microsoft Academic Search

A thorough magnetic investigation of beta-uranium hydride has been carried out. The curve of reciprocal paramagnetic susceptibility against temperature generally follows the Curie-Weiss law and shows the same curvatures near the Curie point and at high temperatures as do the data for the ferromagnetic elements above their Curie points. A considerable number of magnetization curves have been obtained for a

S. T. Lin; A. R. Kaufmann

1956-01-01

102

ENRICHED-URANIUM HYDRIDE CRITICAL ASSEMBLIES  

Microsoft Academic Search

Assemblies considered consist of approximate spheres of enriched-uranium ; hydride composition (approximating UHâ) in 8-in. thick normal uranium and ; nickel reflectors and in a uranium reflector with nickel liner. Data are of the ; following types- (1) critical sizes, (2) values of Rossi alpha in the ; neighborhood of delayed critical, (3) activation rates of various internal ; neutron

G. A. Linenberger; J. D. Orndoff; H. C. Paxton

1960-01-01

103

Hydrogen storage in sodium aluminum hydride  

Microsoft Academic Search

Sodium aluminum hydride, NaAlHâ, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the

Vidvuds Ozolins; J. L. Herberg; Kevin F. McCarty; Robert S. Maxwell; Roland Rudolph Stumpf; Eric H. Majzoub

2005-01-01

104

Electron Microscopy of Hydride Precipitation in Vanadium  

Microsoft Academic Search

Precipitation of hydride from the solid solution of vanadium-hydrogen containing a small amount of hydrogen was observed at temperatures ranging between 300 K and 77 K using the cold stage of a 500 kV electron microscope. Two types of precipitates were found at low temperatures. One has a cubic superstructure with a unit cell twice as large as that of

Toshinobu Chiba; Shigeo Takano

1971-01-01

105

Metal hydride fuel storage and method thereof  

DOEpatents

Disclosed herein is a metal hydride fuel storage cartridge having integrated resistive heaters that can be used in conjunction with fuel cells such as MEMS-based fuel cells. The cartridge is fabricated using micromachining methods and thin/thick film materials synthesis techniques.

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

2006-10-17

106

The Effect of Stress on Hydride Precipitation.  

National Technical Information Service (NTIS)

A major difficulty in comprehending the mechanism of stress induced hydride fracture has been brought to the attention of one of the authors (HKB) by the other two. This difficulty has arisen because a clear distinction was not made between uniformly and ...

T. B. Flannagan N. B. Mason H. K. Birnbaum

1980-01-01

107

THE HYDRIDING OF CERIUM-MAGNESIUM ALLOYS  

Microsoft Academic Search

Cerium-magnesium alloys containing from 0 to 75 at% Mg were subjected to ; hydriding at room temperature at a Hâ pressure of 0.5 to l.0 atm. The ; hydrogen content of the hydrogenated alloy was determined by measuring the ; evolved Hâ on adding HCl to the sample. In alloys containing up to 5 at.% ; Mg a small constant

V. I. Mikheeva; Z. K. Sterlyadkina

1961-01-01

108

Mercury pollution in Tokuyama Bay  

Microsoft Academic Search

The sediments and aquatic life of Tokuyama Bay, Japan, have been polluted by mercury effluent from chloro-alkali plants. In total, about 380 tons mercury were released from these plants and 6.64 tons of mercury were discharged into the bay in waste waters between 1952 and 1975, when mercury cells were employed. A number of surveys to study mercury pollution and

Hiroshi Nakanishi; Masayuki Ukita; Masayuki Sekine; Sadaaki Murakami

1989-01-01

109

Chapter 12 New Expression of the Chemical Bond in Hydrides Using Atomization Energies  

Microsoft Academic Search

Atomization energy diagram is proposed for analyzing the chemical bond in the hydrides including perovskite-type hydrides, metal hydrides and complex hydrides. The atomization energies of hydrogen and metal atoms in them are evaluated theoretically by the energy density analysis (EDA) of the total energy, and used for the construction of the atomization energy diagram. Every hydride can be located on

Yoshifumi Shinzato; Hiroshi Yukawa; Masahiko Morinaga; Takeshi Baba; Hiromi Nakai

2008-01-01

110

Mercury: The World Closest to the Sun.  

ERIC Educational Resources Information Center

|Discusses various topics related to the geology of Mercury including the origin of Mercury's magnetism, Mercury's motions, volcanism, scarps, and Mercury's violent birth and early life. Includes a table comparing Mercury's orbital and physical data to that of earth's. (JN)|

Cordell, Bruce M.

1984-01-01

111

Mercury Calibration System  

SciTech Connect

U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on actual capabilities of the current calibration technology. As part of the current effort, WRI worked with Thermo Fisher elemental mercury calibrator units to conduct qualification experiments to demonstrate their performance characteristics under a variety of conditions and to demonstrate that they qualify for use in the CEM calibration program. Monitoring of speciated mercury is another concern of this research. The mercury emissions from coal-fired power plants are comprised of both elemental and oxidized mercury. Current CEM analyzers are designed to measure elemental mercury only. Oxidized mercury must first be converted to elemental mercury prior to entering the analyzer inlet in order to be measured. CEM systems must demonstrate the ability to measure both elemental and oxidized mercury. This requires the use of oxidized mercury generators with an efficient conversion of the oxidized mercury to elemental mercury. There are currently two basic types of mercuric chloride (HgCl{sub 2}) generators used for this purpose. One is an evaporative HgCl{sub 2} generator, which produces gas standards of known concentration by vaporization of aqueous HgCl{sub 2} solutions and quantitative mixing with a diluent carrier gas. The other is a device that converts the output from an elemental Hg generator to HgCl{sub 2} by means of a chemical reaction with chlorine gas. The Thermo Fisher oxidizer system involves reaction of elemental mercury vapor with chlorine gas at an elevated temperature. The draft interim protocol for oxidized mercury units involving reaction with chlorine gas requires the vendors to demonstrate high efficiency of oxidation of an elemental mercury stream from an elemental mercury vapor generator. The Thermo Fisher oxidizer unit is designed to operate at the power plant stack at the probe outlet. Following oxidation of elemental mercury from reaction with chlorine gas, a high temperature module reduces the mercuric chloride back to elemental mercury. WRI conducted work with a custom laboratory configured stand-alone oxidized mercury generator unit prov

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

2009-03-11

112

Process for low mercury coal  

DOEpatents

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.

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

1995-01-01

113

Process for low mercury coal  

DOEpatents

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.

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

1995-04-04

114

Mercury in Tunas: A Review.  

National Technical Information Service (NTIS)

Mercury in the aquatic environment comes from both natural processes and industrial activities. The latter probably have not significantly altered the mercury content of the high seas where most tunas are captured. Mercury compounds enter aquatic organism...

C. L. Peterson W. L. Klawe G. D. Sharp

1973-01-01

115

Mercury-induced renal effects  

Microsoft Academic Search

Mercury (Hg, CAS Number 7439-97-6) is a naturally-occurring metal that has an atomic number of 80 and an atomic weight of\\u000a 200.6. Many different organic and inorganic mercury compounds are found in nature because of mercury’s ability to form covalent\\u000a and ionic bonds with other chemicals. Mercury exists in three forms in three oxidation states (0, +1, +2): elemental mercury

Bruce A. Fowler; Margaret H. Whittaker; Carl-Gustaf Elinder

116

Missions to Mercury  

Microsoft Academic Search

Mercury is a very difficult planet to observe from the Earth, and space missions that target Mercury are essential for a comprehensive\\u000a understanding of the planet. At the same time, it is also difficult to orbit because it is deep inside the Sun’s gravitational\\u000a well. Only one mission has visited Mercury; that was Mariner 10 in the 1970s. This paper

André Balogh; Réjean Grard; Sean C. Solomon; Rita Schulz; Yves Langevin; Yasumasa Kasaba; Masaki Fujimoto

2007-01-01

117

Mercury toxicity in plants  

Microsoft Academic Search

Mercury poisoning has become a problem of current interest as a result of environmental pollution on a global scale. Natural\\u000a emissions of mercury form two-thirds of the input; manmade releases form about one-third. Considerable amounts of mercury\\u000a may be added to agricultural land with sludge, fertilizers, lime, and manures. The most important sources of contaminating\\u000a agricultural soil have been the

Manomita Patra; Archana Sharma

2000-01-01

118

Mercury, Venus, and Earth!  

NSDL National Science Digital Library

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 ...

Bschiffer

2009-10-21

119

Project Mercury: A Chronology  

NSDL National Science Digital Library

This internet version of an historical NASA (National Aeronautics and Space Administration) publication contains information about Project Mercury, the first manned space flight program in the United States. This document chronicles the three major phases of the Mercury program - conception, research and development, and operation. It includes major events leading to the project, the objectives of each Project Mercury test, flight data and launch summaries. Also provided is a daily log of events and occurrences that took place during this project.

Grimwood, James

1963-01-01

120

Immunology of mercury.  

PubMed

The heavy metal mercury is ubiquitously distributed in the environment resulting in permanent low-level exposure in human populations. Mercury can be encountered in three main chemical forms (elemental, inorganic, and organic) which can affect the immune system in different ways. In this review, we describe the effects of these various forms of mercury exposure on immune cells in humans and animals. In genetically susceptible mice or rats, subtoxic doses of mercury induce the production of highly specific autoantibodies as well as a generalized activation of the immune system. We review studies performed in this model and discuss their implications for the role of environmental chemicals in human autoimmunity. PMID:19076354

Vas, Jaya; Monestier, Marc

2008-11-01

121

Mercury emission from crematoria.  

PubMed

The purpose of this study, undertaken at a cremator representing an example of current equipment and cremation practices in use in Italy, is to assess the possible mercury emitted during cremation and substantiate the current data available. This paper reports some preliminary results concerning mercury and total particulate matter emissions during three cremation processes. The obtained results gave a mercury concentration ranging from 0.005 to 0.300 mg/m3 and a mercury emission factor ranging from 0.036 to 2.140 g/corpse cremated. The total particulate matter concentration range was 1.0 to 2.4 mg/m3. PMID:17124361

Santarsiero, Anna; Settimo, Gaetano; Dell'andrea, Elena

2006-01-01

122

METHOD OF FABRICATING A URANIUM-ZIRCONIUM HYDRIDE REACTOR CORE  

DOEpatents

A method is described of evenly dispersing uranlum metal in a zirconium hydride moderator to produce a fuel element for nuclear reactors. According to the invention enriched uranium hydride and zirconium hydride powders of 200 mesh particle size are thoroughly admixed to form a mixture containing 0.1 to 3% by weight of U/sup 235/ hydride. The mixed powders are placed in a die and pressed at 100 tons per square inch at room temperature. The resultant compacts are heated in a vacuum to 300 deg C, whereby the uranium hydride deoomposes into uranium metal and hydrogen gas. The escaping hydrogen gas forms a porous matrix of zirconium hydride, with uramum metal evenly dispersed therethrough. The advantage of the invention is that the porosity and uranium distribution of the final fuel element can be more closely determined and controlled than was possible using prior methods of producing such fuel ele- ments.

Weeks, I.F.; Goeddel, W.V.

1960-03-22

123

SANS Measurement of Hydrides in Uranium  

SciTech Connect

SANS scattering is shown to be an effective method for detecting the presence of hydrogen precipitates in uranium. High purity polycrystalline samples of depleted uranium were given several hydriding treatments which included extended exposures to hydrogen gas at two different pressures at 630 C as well as a furnace anneal at 850 C followed by slow cooling in the near absence hydrogen gas. All samples exhibited neutron scattering that was in proportion to the expected levels of hydrogen content. While the scattering signal was strong, the shape of the scattering curve indicated that the scattering objects were large sized objects. Only by use of a very high angular resolution SANS technique was it possible to make estimates of the major diameter of the scattering objects. This analysis permits an estimate of the volume fraction and means size of the hydride precipitates in uranium.

Spooner, S; Ludtka, G.M.; Bullock, J.S.; Bridges, R.L.; Powell, G.L.

2001-09-04

124

Numerical study of a magnesium hydride tank  

NASA Astrophysics Data System (ADS)

Hydrogen storage in metal hydride tanks (MHT) is a very promising solution. Several experimental tanks, studied by different teams, have already proved the feasibility and the interesting performances of this solution. However, in much cases, an optimization of tank geometry is still needed in order to perform fast hydrogen loading. The development of efficient numerical tools is a key issue for MHT design and optimization. We propose a simple model representing a metal hydride tank exchanging its heat of reaction with a thermal fluid flow. In this model, the radial and axial discretisations have been decoupled by using Matlab® one-dimensional tools. Calculations are compared to experimental results obtained in a previous study. A good agreement is found for the loading case. The discharging case shows some discrepancies, which are discussed in this paper.

Delhomme, Baptiste; de Rango, Patricia; Marty, Philippe

2012-11-01

125

Electronic structure of light metal hydrides  

NASA Astrophysics Data System (ADS)

The equilibrium lattice constant, cohesive energy, and electron density of states of light metal hydrides (LiBeH3, LiMgH3, LiCaH3, NaMgH3, and LiBH3) are calculated using the linear combination of muffin-tin orbitals method on a perovskite lattice structure. Large gaps in the density of states appear at the Fermi energy of LiBeH3, LiMgH3, LiCaH3, and NaMgH3 indicating that these classes of hydrides are insulators. LiBH3, on the other hand, is metallic and could have interesting electronic properties.

Khowash, P. K.; Rao, B. K.; McMullen, T.; Jena, P.

1997-01-01

126

Hydrogen-diffusion-rate-limited hydriding and dehydriding kinetics  

Microsoft Academic Search

Hydriding and dehydriding kinetics are derived within the framework of the Johnson-Mehl-Avrami equation. Hydriding is considered to be rate limited by hydrogen diffusion through a growing hydride layer, and dehydriding by hydrogen diffusion through a growing metal layer. Incubation time effects due to surface contamination are taken into account by a delayed nucleation function. The dominant composition-dependent terms in the

P. S. Rudman

1979-01-01

127

A theoretical and experimental study of hydrides in zirconium alloys  

Microsoft Academic Search

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

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

2006-01-01

128

ToF-SIMS characterization of uranium hydride  

Microsoft Academic Search

Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) has been employed for the first time to investigate uranium hydride. The deuterated form of uranium hydride (UD3) was formed on a polycrystalline uranium sample by exposure to high-purity D2 gas at room temperature. The characteristic positive and negative secondary-ion fragments observed from uranium hydride are reported and assigned. Our investigations show that negative-ion fragments

P. Morrall; D. W. Price; A. J. Nelson; W. J. Siekhaus; E. Nelson; K. J. Wu; M. Stratman; W. McLean II

2007-01-01

129

HYDRIDE-RELATED DEGRADATION OF SNF CLADDING UNDER REPOSITORY CONDITIONS  

SciTech Connect

The purpose and scope of this analysis/model report is to analyze the degradation of commercial spent nuclear fuel (CSNF) cladding under repository conditions by the hydride-related metallurgical processes, such as delayed hydride cracking (DHC), hydride reorientation and hydrogen embrittlement, thereby providing a better understanding of the degradation process and clarifying which aspects of the process are known and which need further evaluation and investigation. The intended use is as an input to a more general analysis of cladding degradation.

K. McCoy

2000-12-12

130

Fabrication and characterization of uranium–thorium–zirconium hydrides  

Microsoft Academic Search

Two uranium–thorium–zirconium hydrides, (UTh4Zr10)H1.9 and (U4Th2Zr9)H1.5, have been fabricated and characterized. Fabrication involved arc melting of the constituent pure metals to form homogenous alloys, followed by hydriding at elevated temperatures in a hydrogen gas environment. The compounds were characterized by X-ray powder diffractometry as well as scanning and transmission electron microscopy. These methods revealed a multi-phase mixture of ?-zirconium hydride

Kurt A. Terrani; G. W. Chinthaka Silva; Charles B. Yeamans; Mehdi Balooch; Donald R. Olander

2009-01-01

131

Triethylborane-induced radical reactions with gallium- and indium hydrides  

Microsoft Academic Search

A gallium hydride reagent, HGaCl2, was found to act as a radical mediator. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium

Kazuaki Takami; Satoshi Mikami; Hideki Yorimitsu; Hiroshi Shinokubo; Koichiro Oshima

2003-01-01

132

Radiotracer investigation of hydride trapping efficiency within a graphite furnace  

Microsoft Academic Search

Efficiencies of hydride generation and in situ trapping in the transversely heated graphite furnace by using Pd modifier were studied for selenium hydride, arsine and stibine by means of the radiotracers 75Se, 76As and 122Sb. The influence of four experimental parameters, i.e. Pd modifier mass, trapping temperature, carrier gas flow rate and the distance of the hydride introduction capillary from

B. Do?ekal; J. D?dina; V. Krivan

1997-01-01

133

Electrochromism of Mg-Ni hydride switchable mirrors  

Microsoft Academic Search

Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 less than z less than 3.7 shows that addition of one Mg atom per Mg2Ni

Jan Isidorsson; I. A. Giebels; M. Di Vece; Ronald Griessen

2001-01-01

134

Dissipative hydride precipitates in superconducting niobium cavities  

SciTech Connect

We report the first direct observation of the microstructural features exhibiting RF losses at high surface magnetic fields of above 100 mT in field emission free superconducting niobium cavities. The lossy areas were identified by advanced thermometry. Surface investigations using different techniques were carried out on cutout samples from lossy areas and showed the presence of dendritic niobium hydrides. This finding has possible implications to the mechanisms of RF losses in superconducting niobium at all field levels.

Romanenko, A.; Cooley, L.D.; /Fermilab; Ciovati, G.; / /Jefferson Lab; Wu, G.; /Argonne

2011-10-01

135

Uranium–zirconium hydride fuel properties  

Microsoft Academic Search

Properties of the two-phase hydride U0.3ZrH1.6 pertinent to performance as a nuclear fuel for LWRs are reviewed. Much of the available data come from the Space Nuclear Auxiliary Power (SNAP) program of 4 decades ago and from the more restricted data base prepared for the TRIGA research reactors some 3 decades back. Transport, mechanical, thermal and chemical properties are summarized.

D. Olander; Ehud Greenspan; Hans D. Garkisch; Bojan Petrovic

2009-01-01

136

Separation of hydrogen isotopes with uranium hydride  

Microsoft Academic Search

The isotope effect on the decomposition behavior of uranium hydride is examined, since the separation of hydrogen isotopes is one of the most important processes in fission and fusion power generating systems. The decomposition equilibrium pressure is measured for UH3, UD3, and UH(1.5)D(1.5) in the temperature range of 500-700 K; the decomposition pressure of UD3 is higher than that of

S. Imoto; T. Tanabe; K. Utsunomiya

1981-01-01

137

PULSE HEATING OF ZIRCONIUM-URANIUM HYDRIDES  

Microsoft Academic Search

Apparatus and techniques for measuring power input, electric ; resistivity, temperature, and amount and rate of hydrogen released from Zr--U ; hydrides, (ZrU\\/sub 0.04\\/H\\/sub 1.8 plus or minus 0.1) during transient conditions ; are described. Data are presented for six samples that were heated to their ; destruction. Initial heating rates were about 7500 deg C\\/sec; however, as H ;

R. E. Taylor; H. G. Weidberg; R. T. Albee

1962-01-01

138

Fatigue Crack Growth In Lithium Hydride  

Microsoft Academic Search

Subcritical fatigue crack growth, from cyclic tensile loading, was demonstrated in warm pressed Polycrystalline lithium hydride. Experiments were performed with cyclic tension-tension crack opening (mode I) loads applied to a pre-cracked compact type specimen in an argon environment at a temperature of 21C (70F). The fatigue crack growth was found to occur between 7.56 Ã 10{sup -ll} M\\/cycle (2.98 Ã

T E Healy

1993-01-01

139

Density Functional Screening of Metal Hydride Reactions  

NASA Astrophysics Data System (ADS)

The on-board storage of hydrogen is one of the most vexing problems associated with the development of viable fuel cell vehicles. Hydrides of period 2 or 3 metals can store hydrogen at high gravimetric and volumetric densities. However, existing hydrides either have unacceptable thermodynamics or kinetics. New materials for hydrogen storage are therefore needed. We demonstrate how first principles density functional theory (DFT) can be used to screen potential candidate materials for hydrogen storage. We have used DFT calculations in conjunction with a free energy analysis to screen over a million reactions involving 212 known compounds. This approach has identified several interesting reaction schemes that have not yet been explored experimentally. We have computed the phonon density of states and used this information to predict the van't Hoff plots for some of the most promising candidate reactions identified though our modeling. We have also examined the thermodynamics of thin films and nanoparticles for selected metal hydrides by accounting for the surface energies of the films or nanoparticles.

Johnson, Karl; Alapati, Sudhakar; Dai, Bing; Kim, Ki-Chul; Sholl, David

2008-03-01

140

METHOD AND APPARATUS FOR MAKING URANIUM-HYDRIDE COMPACTS  

DOEpatents

A method and apparatus are presented for making compacts of pyrophoric hydrides in a continuous operation out of contact with air. It is particularly useful for the preparation of a canned compact of uranium hydride possessing high density and purity. The metallic uranium is enclosed in a container, positioned in a die body evacuated and nvert the uranium to the hydride is admitted and the container sealed. Heat is applied to bring about the formation of the hydride, following which compression is used to form the compact sealed in a container ready for use.

Wellborn, W.; Armstrong, J.R.

1959-03-10

141

Materials compatibility and wall stresses in hydride storage beds  

SciTech Connect

Hydrogen isotope handling and storage will be accomplished using solid-state hydride compounds at the Savannah River Site in the new Replacement Tritium Facility (RTF). The hydride powder is contained in a horizontal cylindrical vessel, and the combination of hydride powder, vessel, and associated heating and cooling facilities are termed in a hydride storage bed. The materials compatibility of the storage powder with the stainless steel vessel has been examined, and the stresses developed in the vessel due to expansion of the powder by absorbing hydrogen have been measured.

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

1991-12-31

142

Determination of mercury and organic mercury contents in Malaysian seafood  

Microsoft Academic Search

The contents of mercury and organic mercury in various types of seafood from various location in Malaysia were determined by neutron activation analysis. Total mercury was determined by instrumental neutron activation analysis (INAA) whilst organic mercury was determined by INAA after chemical separation. Samples were digested in acid media and into the solution was added copper ion and KBr to

S. A. Rahman; A. K. Wood; S. Sarmani; A. A. Majid

1997-01-01

143

Retrieval of Mercury from Wastewater as Stable Mercury Ferrite  

Microsoft Academic Search

Mercury contamination in water and wastewater is a global risk and health problem. So there is a concrete need for an eco-friendly process that can remove the toxic mercury ions as well as convert the mercury to a value added product. The black ferruginous mercury ferrite (FMF) as a value added product was synthesized by coprecipitation technique at 50 o

Prashant D. Zade; Dattatray M. Dharmadhikari

2007-01-01

144

Mercury pollution in China  

Microsoft Academic Search

With a long history of mercury mining and use and a rapidly growing economy that relies heavily on coal for heat and energy, China faces an enormous challenge to reduce pollution from this toxic metal. The authors delineate what is known about the extent of the problem, regulatory steps are being taken to reduce mercury pollution, and next steps for

Gui-Bin Jiang; Jian-Bo Shi; Xin-Bin Feng

2006-01-01

145

Atmospheric Deposition of Mercury  

EPA Science Inventory

With the advent of the industrial era, the amount of mercury entering the global environment increased dramatically. Releases of mercury in its elemental form from gold mines and chlor-alkali plants, as sulfides such as mercaptans and agricultural chemicals, and as volatile emiss...

146

Mercury in the environment  

ScienceCinema

Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

147

The Nine Planets: Mercury  

NSDL National Science Digital Library

This page of Nine Planets highlights details about the planet Mercury. Information includes planet diameter, mass, distance from the Sun, orbit, and mythology. Also covered are composition, surface features, atmosphere and magnetic field data, and the results of exploration spacecraft. The site provides links to images, movies, and more Mercury facts. Unanswered questions about the planet are also discussed.

Arnett, Bill

148

Modeling Mercury's Calcium Exosphere  

Microsoft Academic Search

Three elements (H, He, O) were seen in emission in Mercury's atmosphere by the UV spectrometer onboard the Mariner 10 spacecraft (Broadfoot et al., Science 185, 1974). Two additional species (Na and K) were discovered by Potter and Morgan two decades later using ground-based telescopes (Potter and Morgan, Science 229, 1985; Icarus 67, 1986). Calcium was discovered in Mercury's exosphere

R. Killen; T. Bida; M. Sarantos; D. Boice

2002-01-01

149

Mercury's Seasonal Sodium Exosphere  

NASA Astrophysics Data System (ADS)

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.

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

150

Getting rid of mercury  

SciTech Connect

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.

Reisch, M.S.

2008-11-24

151

Mercury Exposure and Children's Health  

Microsoft Academic Search

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

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

2010-01-01

152

Getting Mercury out of Schools.  

ERIC Educational Resources Information Center

|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…

1999

153

Organic mercury compounds and autoimmunity  

Microsoft Academic Search

Based on in vitro studies and short-term in vivo studies, all mercurials were for a long time considered as prototypic immunosuppressive substances. Recent studies have confirmed that organic mercurials such as methyl mercury (MeHg) and ethyl mercury (EtHg) are much more potent immunosuppressors than inorganic mercury (Hg). However, Hg interacts with the immune system in the presence of a susceptible

Said Havarinasab; Per Hultman

2005-01-01

154

Metal Hydride Thermal Storage: Reversible Metal Hydride Thermal Storage for High-Temperature Power Generation Systems  

SciTech Connect

HEATS Project: PNNL is developing a thermal energy storage system based on a Reversible Metal Hydride Thermochemical (RMHT) system, which uses metal hydride as a heat storage material. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. PNNL’s metal hydride material can reversibly store heat as hydrogen cycles in and out of the material. In a RHMT system, metal hydrides remain stable in high temperatures (600- 800°C). A high-temperature tank in PNNL’s storage system releases heat as hydrogen is absorbed, and a low-temperature tank stores the heat until it is needed. The low-cost material and simplicity of PNNL’s thermal energy storage system is expected to keep costs down. The system has the potential to significantly increase energy density.

None

2011-12-05

155

Tributylgermanium hydride as a replacement for tributyltin hydride in radical reactions.  

PubMed

Tributylgermanium hydride (Bu(3)GeH) can be used as an alternative to tributyltin hydride (Bu(3)SnH) as a radical generating reagent with a wide range of radical substrates. Tributylgermanium hydride has several practical advantages over tributyltin hydride, e.g. low toxicity, good stability and much easier work-up of reactions. The reagent can be easily prepared in good yield and stored indefinitely. Suitable substrates include iodides, bromides, activated chlorides, phenyl selenides, tert-nitroalkanes, thiocarbonylimidazolides and Barton esters. Alkyl, vinyl and aryl radicals can be generated in radical reactions including reduction and cyclisation processes. Common radical initiators such as ACCN and triethylborane can be used. The slower rate of hydrogen abstraction by carbon-centred radicals from Bu(3)GeH as compared to Bu(3)SnH facilitates improved cyclisation yields. Polarity reversal catalysis (PRC) with phenylthiol can be used in reactions which generate stable radical intermediates which will not abstract hydrogen from Bu(3)GeH. PMID:14770238

Russell Bowman, W; Krintel, Sussie L; Schilling, Mark B

2004-01-22

156

Hydride reactor apparatus for hydrogen comminution of metal hydride hydrogen storage material  

Microsoft Academic Search

This patent describes an apparatus for size reduction of metal hydride hydrogen storage alloy material. It comprises: a reactor body having a substantially hollow interior volume. The volume divided into at least two regions, a comminuting first region and a collection second region; at least one reaction gas inlet port into the hollow interior volume and one reaction gas outlet

M. A. Fetcenko; T. Kaatz; S. P. Summer; J. LaRocca

1990-01-01

157

METHOD AND APPARATUS FOR MAKING URANIUM-HYDRIDE COMPACTS  

Microsoft Academic Search

A method and apparatus are presented for making compacts of pyrophoric ; hydrides in a continuous operation out of contact with air. It is particularly ; useful for the preparation of a canned compact of uranium hydride possessing high ; density and purity. The metallic uranium is enclosed in a container, positioned ; in a die body evacuated and nvert

W. Wellborn; J. R. Armstrong

1959-01-01

158

A nickel metal hydride battery for electric vehicles  

Microsoft Academic Search

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

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

1993-01-01

159

Out-of-Pile Accelerated Hydriding of Zircaloy Fasteners.  

National Technical Information Service (NTIS)

Mechanical joints between Zircaloy and nickel-bearing alloys, mainly the Zircaloy-4/Inconel-600 combination, were exposed to water at 450 exp 0 F and 520 exp 0 F to study hydriding of Zircaloy in contact with a dissimilar metal. Accelerated hydriding of t...

J. C. Clayton

1979-01-01

160

The incipient kinetics of hydride growth on cerium surfaces  

Microsoft Academic Search

The incipient hydriding stage of cerium is characterized by nucleation and growth of the hydride phase on the surface of the metal. The kinetics of this initial growth process were studied utilizing a hot-stage microscope (HSM) equipped with a video camera. Growth velocities of nuclei were determined as a function of reaction temperature and hydrogen pressure over a grid of

M. Brill; J. Bloch; D. Shmariahu; M. H. Mintz

1995-01-01

161

Mercury Study Report to Congress. Volume 4. Health Effects of Mercury and Mercury Compounds. SAB Review Draft.  

National Technical Information Service (NTIS)

This volume of the draft Mercury Study Report to Congress summarizes the available information on human health effects and animal data for hazard identification and dose-response assessment for three forms of mercury: elemental mercury, mercury chloride (...

R. Schoeny

1996-01-01

162

Mercury in the ecosystem  

SciTech Connect

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.

Mitra, S.

1986-01-01

163

A novel plating process for microencapsulating metal hydrides  

SciTech Connect

One approach to increasing the lifetime of the metal hydride electrode has been the use of conventional electroless plating to produce a coating of copper or nickel on the surface of the metal hydride powders. In this paper, a novel method for microencapsulating the active electrode powders is presented. This new plating technique takes advantage of the reducing power of hydrogen already stored inside the metal hydride to plate a variety of metals onto metal hydride materials. This method greatly simplifies electroless plating for these powders, eliminating the need for stabilizers and additives typically required for conventional electroless plating solutions. Metals that can be electrolessly plated with stored hydrogen have been identified based on thermodynamic considerations. Experimentally, micrometers thick coatings of copper, silver, and nickel have been plated on several metal hydrides.

Law, H.H.; Vyas, B.; Zahurak, S.M.; Kammlott, G.W. [AT and T Bell Labs., Murray Hill, NJ (United States)

1996-08-01

164

Porous metal hydride composite and preparation and uses thereof  

DOEpatents

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.

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

1980-03-12

165

Porous metal hydride composite and preparation and uses thereof  

DOEpatents

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.

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

1982-01-01

166

Inorganic: the other mercury.  

PubMed

There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials. PMID:18044248

Risher, John F; De Rosa, Christopher T

2007-11-01

167

Exploring the Planets: Mercury  

NSDL National Science Digital Library

This site contains most of the up-to-date information known about the planet Mercury. Facts about the planet include: mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), and diameter. The site explains why earth-based views of Mercury are so poor and describes the surface of the planet on the basis of probe photographs. The photographs do not prove whether the material on the surface is impact ejecta or volcanic. However, a colored digital mosaic of Mercury taken by Mariner 10 suggests that at least some of the mercurian smooth plains are the products of volcanism.

168

Analysis of germanium hydride molecular clusters.  

PubMed

Isotope clusters in library electron ionization mass spectra of germanes often appear a few u lower than theoretically expected from elemental composition; for example, the dominant peak of the Ge(4)H(10)(+) pattern is shifted 8 u down. This phenomenon is due to combinations of three essential components: the molecular ion Ge(n)H(2n+2)(+) and two products of hydrogen elimination, Ge(n)H(+) and Ge (n)(+) . Using these components, isotope clusters can be accurately projected for germanium hydrides from Ge(2)H(6) up to Ge(5)H(12). PMID:21472557

Gor?czko, Andrzej J

2011-01-28

169

Hydrogen isotope effects in titanium alloy hydrides  

SciTech Connect

The tritium exchange method was used to determine the isotope effects on a large number of metal-hydrogen systems. Ti was chosen as a constant constitutent in the systems, and the other metals chosen were V, Cr, Mo, Mn, Co, and Ni. The tritium distribution coefficient was determined at temperatures of -20, 0, +20, or 40/sup 0/C and at nearly constant hydrogen pressure. A plot was made of the distribution coefficient of tritium vs the periodic table sequence for 1:1 Ti alloy hydrides, and the plot indicates greatest separation factor for Ti--CrH/sub 2/ alloy. (BLM)

Tanaka, J.; Wiswall, R.H.; Reilly, J.J.

1978-02-01

170

Mercury study report to Congress. Volume 4. Health effects of mercury and mercury compounds. Sab review draft  

Microsoft Academic Search

This volume of the draft Mercury Study Report to Congress summarizes the available information on human health effects and animal data for hazard identification and dose-response assessment for three forms of mercury: elemental mercury, mercury chloride (inorganic mercury), and methylmercury (organic mercury). Effects are summarized by endpoint. The risk assessment evaluates carcinogenicity, mutagenicity, developmental toxicity and general systemic toxicity of

Schoeny

1996-01-01

171

Recovery of mercury from mercury compounds via electrolytic methods  

DOEpatents

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

Grossman, Mark W. (Belmont, MA); George, William A. (Rockport, MA)

1988-01-01

172

Recovery of mercury from mercury compounds via electrolytic methods  

DOEpatents

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figs.

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

1989-11-07

173

Recovery of mercury from mercury compounds via electrolytic methods  

DOEpatents

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

Grossman, Mark W. (Belmont, MA); George, William A. (Rockport, MA)

1989-01-01

174

Recovery of mercury from mercury compounds via electrolytic methods  

DOEpatents

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figures.

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

1991-06-18

175

Recovery of mercury from mercury compounds via electrolytic methods  

DOEpatents

A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

Grossman, Mark W. (Belmont, MA); George, William A. (Rockport, MA)

1991-01-01

176

Mercury Exposure and Children's Health  

PubMed Central

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.

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

2011-01-01

177

Separation of hydrogen isotopes with uranium hydride  

NASA Astrophysics Data System (ADS)

The isotope effect on the decomposition behavior of uranium hydride is examined, since the separation of hydrogen isotopes is one of the most important processes in fission and fusion power generating systems. The decomposition equilibrium pressure is measured for UH3, UD3, and UH(1.5)D(1.5) in the temperature range of 500-700 K; the decomposition pressure of UD3 is higher than that of UH3, and UH(1.5)D(1.5) shows an intermediate decomposition pressure. The enthalpy and entropy formations are obtained and they are in good agreement with those determined by a calorimetric study. When the reaction reaches the point of equilibrium, deuterium is enriched in the gas phase, and the separation factor is approximately 1.3. Experiments on deuterium enrichment, made with a small cascade, also show a separation factor of about 1.3. A thermodynamic model for the case where the mixed hydride is the regular solution, is used, and it is shown that the separation factor is larger for gas mixtures with a high D/H ratio at higher temperatures and for those with a low D/H ratio at lower temperatures.

Imoto, S.; Tanabe, T.; Utsunomiya, K.

178

Regeneration of Aluminum Hydride Using Trimethylamine  

SciTech Connect

Aluminum hydride is an attractive reducing agent and energy storage compound possessing a low decomposition temperature and a high gravimetric and volumetric hydrogen density. However, it is thermodynamically unstable at room temperature and requires extremely high pressures to form the hydride from aluminum and hydrogen gas. Here, we describe an alternate method of synthesizing AlH{sub 3} using Ti-catalyzed Al powder, H{sub 2}, and trimethylamine (TMA) to form an alane adduct. The formation of trimethylamine alane occurs at modest hydrogen pressures ({approx}100 bar), forming the 2:1 bis complex (2 trimethylamine/AlH{sub 3}). Along with the hydrogenation product, mono (1:1) and bis (2:1) standards of TMA-AlH{sub 3} were prepared and characterized using X-ray diffraction and Raman spectroscopy. X-ray absorption spectroscopy of the reaction products showed that the Ti catalyst remains with the unreacted Al powder after hydrogenation and is not present in the alane adduct. We also demonstrate that TMA can be transaminated with triethylamine to form triethylamine alane, which can easily be separated to recover AlH{sub 3}.

D Lacina; J Reilly; Y Celebi; J Wegrzyn; J Johnson; J Graetz

2011-12-31

179

Method and apparatus for monitoring mercury emissions  

DOEpatents

A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber.

Durham, Michael D. (Castle Rock, CO); Schlager, Richard J. (Aurora, CO); Sappey, Andrew D. (Golden, CO); Sagan, Francis J. (Lakewood, CO); Marmaro, Roger W. (Littleton, CO); Wilson, Kevin G. (Littleton, CO)

1997-01-01

180

Method and apparatus for monitoring mercury emissions  

DOEpatents

A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber. 15 figs.

Durham, M.D.; Schlager, R.J.; Sappey, A.D.; Sagan, F.J.; Marmaro, R.W.; Wilson, K.G.

1997-10-21

181

Exploring Mercury: MESSENGER's Mission  

NASA Astrophysics Data System (ADS)

NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched on 3 August 2004, is well into its voyage of discovery. The mission, spacecraft, and payload are designed to answer six fundamental questions regarding the innermost planet, thus initiating a new era in our understanding of the terrestrial planets; (1) Why is Mercury so dense? (2) What is Mercury's geologic history? (3) What are the nature and origin of Mercury's magnetic field? (4) What is the structure of Mercury's core? (5) What are the unusual materials at the poles? (6) What volatiles are important at Mercury? The answers to these questions are all pieces of an interconnecting puzzle that will expand our understanding of the formation and evolution of the terrestrial planets as a group. The mission, currently in its cruise phase, has been focused on commissioning the spacecraft and science payload in addition to planning for flyby and orbital operations. The second Venus flyby (June 2007) will complete final rehearsals for the Mercury flyby operations (January and October 2008 and September 2009). The flybys will be used to image the hemisphere of the planet not seen by Mariner 10 and to obtain high-resolution spectral observations with which to map surface mineralogy and assay the exosphere. The orbital phase (beginning in March 2011) is a one-year-long, near-polar-orbital observational campaign. The orbital phase will complete gloal imaging, yield detailed surface compositional and topographic data over the northern hemisphere, determine the geometry of Mercury's internal magnetic field, and inventory exospheric neutrals and magnetospheric charged particle species.

Domingue, Deborah; Solomon, S. C.; McNutt, R. L.; Gold, R. E.; Leary, J. C.; Grant, D. G.; MESSENGER Team

2006-09-01

182

Mercury CEM Calibration  

SciTech Connect

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.

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

2007-03-31

183

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.

184

Synthesis and Hydride Transfer Reactions of Cobalt and Nickel Hydride Complexes to BX3 Compounds  

SciTech Connect

Hydrides of numerous transition metal complexes can be generated by the heterolytic cleavage of H{sub 2} gas such that they offer alternatives to using main group hydrides in the regeneration of ammonia borane, a compound that has been intensely studied for hydrogen storage applications. Previously, we reported that HRh(dmpe){sub 2}, dmpe = 1,2-bis(dimethylphosphinoethane) was capable of reducing a variety of BX{sub 3} compounds having hydride affinity (HA) greater than or equal to HA of BEt{sub 3}. This study examines the reactivity of less expensive cobalt and nickel hydride complexes, (HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +}), to form B-H bonds. The hydride donor abilities ({Delta}G{sub H{sup -}}{sup o}) of HCo(dmpe){sub 2} and [HNi(dmpe){sub 2}]{sup +} were positioned on a previously established scale in acetonitrile that is cross-referenced with calculated HAs of BX{sub 3} compounds. The collective data guided our selection of BX{sub 3} compounds to investigate and aided our analysis of factors that determine favorability of hydride transfer. HCo(dmpe){sub 2} was observed to transfer H{sup -} to BX{sub 3} compounds with X = H, OC{sub 6}F{sub 5} and SPh. The reaction with B(SPh){sub 3} is accompanied by formation of (BH{sub 3}){sub 2}-dmpe and (BH{sub 2}SPh){sub 2}-dmpe products that follow from reduction of multiple BSPh bonds and loss of a dmpe ligand from Co. Reactions between HCo(dmpe){sub 2} and B(SPh){sub 3} in the presence of triethylamine result in formation of Et{sub 3}N-BH{sub 2}SPh and Et{sub 3}N-BH{sub 3} with no loss of dmpe ligand. Reactions of the cationic complex [HNi(dmpe){sub 2}]{sup +} with B(SPh){sub 3} under analogous conditions give Et{sub 3}N-BH{sub 2}SPh as the final product along with the nickel-thiolate complex [Ni(dmpe){sub 2}(SPh)]{sup +}. The synthesis and characterization of HCo(dedpe){sub 2} (dedpe = diethyldiphenyl(phosphino)ethane) from H{sub 2} and a base is also discussed; including the formation of an uncommon trans dihydride species, trans-[(H{sub 2})Co(dedpe){sub 2}][BF{sub 4}].

Mock, Michael T.; Potter, Robert G.; O'Hagan, Molly J.; Camaioni, Donald M.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.

2011-12-05

185

To Mercury dynamics  

NASA Astrophysics Data System (ADS)

Present significance of the study of rotation of Mercury considered as a core-mantle system arises from planned Mercury missions. New high accurate data on Mercury's structure and its physical fields are expected from BepiColombo mission (Anselmi et al., 2001). Investigation of resonant rotation of Mercury, begun by Colombo G. (1966), will play here main part. New approaches to the study of Mercury dynamics and the construction of analytical theory of its resonant rotation are suggested. Within these approaches Mercury is considered as a system of two non-spherical interacting bodies: a core and a mantle. The mantle of Mercury is considered as non-spherical, rigid (or elastic) layer. Inner shell is a liquid core, which occupies a large ellipsoidal cavity of Mercury. This Mercury system moves in the gravitational field of the Sun in resonant traslatory-rotary regime of the resonance 3:2. We take into account only the second harmonic of the force function of the Sun and Mercury. For the study of Mercury rotation we have been used specially designed canonical equations of motion in Andoyer and Poincare variables (Barkin, Ferrandiz, 2001), more convenient for the application of mentioned methods. Approximate observational and some theoretical evaluations of the two main coefficients of Mercury gravitational field J_2 and C22 are known. From observational data of Mariner-10 mission were obtained some first evaluations of these coefficients: J_2 =(8± 6)\\cdot 10-5(Esposito et al., 1977); J_2 =(6± 2)\\cdot 10-5and C22 =(1.0± 0.5)\\cdot 10-5(Anderson et al., 1987). Some theoretical evaluation of ratio of these coefficients has been obtained on the base of study of periodic motions of the system of two non-spherical gravitating bodies (Barkin, 1976). Corresponding values of coefficients consist: J_2 =8\\cdot 10-5and C22 =0.33\\cdot 10-5. We have no data about non-sphericity of inner core of Mercury. Planned missions to Mercury (BepiColombo and Messenger) promise to obtain new and accurate data about dynamics and structure of this planet (Anselmi et al., 2001). There are also some evaluations of moments of inertia Mercury and its core: C/(mR^2)=0.35, C_m /C=0.5± 0.07, (Peal, 1996). Here C and C_m are the moments of inertia of the full Mercury and of its core, m and R is a mass and a mean radius of Mercury. Based on two methods, we consider the rotation of Mercury in the gravitational field of the Sun. First method of perturbation has been effectively applied to the construction of a rotational theory of the Earth for its models as two or three layer celestial body moving in gravitational fields of the Moon, Sun and planets in wide set of papers ranging in 1999-2001 years of Ferrandiz J.M. and Getino J.(2001). Some generalization of this Hamiltonian formalism on the case of cavity (core) with arbitrary dynamical and geometrical oblateness has been obtained in a paper (Barkin, Ferrandiz, 2001). Another method is an analytical method of construction of the resonant rotational motion of synchronous satellites and Mercury, considered as non-spherical rigid bodies. This method has been applied earlier to construction of an analytical theory of rotation of the Moon considered as rigid non-spherical body (Barkin, 1989). Here we modified these methods to apply them to the study of the resonant rotation of a two-layer Mercury. By this we use very effective for the application of perturbation methods and dynamical geometrical illustration of canonical equations in Andoyer and Poincare variables. Main resonant properties of Mercury motion were been described first as generalized Cassini's laws (Colombo, 1966). But Colombo and some anothers scientists (Peal, 1969; Beletskii, 1972; Ward, 1975 and oth.) considered Mercury as rigid non-spherical body sometimes taking into account tidal deformation. Here we have been obtained and formulated these laws and their generalization for a two-layer model of Mercury. On the next step we have evaluated frequencies of free oscillations of core-mantle system of Mercury. Based on the mentioned data about Mercu

Barkin, Yu. V.; Ferrandiz, J. M.

186

Anisotropic behavior and rupture of hydrided Zircaloy-4 sheets  

SciTech Connect

In a French pressurized water reactor (PWR), most of the structural parts of the fuel assembly consist of zirconium alloys (ZIRCALOY-2). The mechanical behavior of ZIRCALOY-4 sheets is investigated at room temperature. The effect of hydride precipitation on the mechanical behavior and on the rupture mechanism is also studied, in the range from 200 to 1,200 wt ppm hydrogen and for different stress triaxialities. It is shown that the material exhibits a strong anisotropy die to its pronounced texture, and that its mechanical properties depend on the strain rate. Hydride precipitation appears to have no effect on the anisotropy or on the strain-rate sensitivity, in the range from 10{sup {minus}4} to 10{sup {minus}2} s{sup {minus}1}. The main effect of hydrogen is the reduction of the ductility and of crack resistance. The ductile rupture mechanism is studied, focusing on the stage of damage nucleation by hydride fracture. Observations during scanning electron microscopy (SEM) in situ tests show that hydrides allow the transmission of slip, which occurs in ZIRCALOY-4 grains. Hydrides can also deform, together with surrounding zirconium matrix. Damage appears after a plastic-strain yield of about 14 to 25 pct. Fracture occurs first on intergranular hydrides. Fracture of transgranular hydrides is observed only prior to failure, for higher plastic strains.

Grange, M.; Besson, J.; Andrieu, E.

2000-03-01

187

Finite element analysis for steady-state hydride-induced fracture in metals by composite model  

Microsoft Academic Search

Delayed hydride cracking, which is observed in hydride-forming metals, due to the precipitation of hydrides near the crack tip, is investigated under conditions of constant temperature and crack velocity, plane strain and small-scale hydride-precipitation. The coupling of the operating physical processes of hydrogen-diffusion, hydride precipitation and material deformation is taken into account. The material is assumed to be an elastic

J. L. Feng; A. G. Varias; Y. K. Sui

2006-01-01

188

Mercury and Mink. II. Experimental methyl mercury intoxication.  

PubMed Central

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.

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

1976-01-01

189

Spectrophotometric properties of Mercury  

NASA Astrophysics Data System (ADS)

The MEcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft obtained photometric observations of Mercury during three flybys (14 January 2008, 6 October 2008, 29 September 2009) using both the Mercury Dual Imaging System (MDIS) and the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). The MDIS measurements include disk-integrated phase-curve observations taken in 11 narrow-band filters ranging from 430 to 1010 nm. The MDIS measurements also include disk-resolved photometric observations taken during the first flyby of a 200-km by 400-km region (centered on 1.7°S, 123.5°E, and spanning 5.5° of latitude and 10° of longitude) over a phase-angle range between 51° and 120°. The MASCS measurements include disk-integrated phase-curve observations taken from 300 to 1450 nm at a spectral resolution of 2.5 nm. During the third flyby, targeted type regions were observed at multiple viewing geometries, providing disk-resolved photometric measurements at high spectral resolution. Comparisons with ground-based observations show that the phase behavior determined by analysis of the MDIS and MASCS observations is consistent with previous studies. Reflectance measurements from the first two flybys show no definitive absorption features and a distinctive steep, or “red,” slope with increasing wavelength common to space-weathered rocky surfaces. The MDIS spectra show evidence of phase reddening (increased spectral slope with increasing phase angle), similar to that observed on the Moon. The derived photometric properties indicate a more compact, less porous regolith that is smoother on meter scales than regolith on the Moon or S-type asteroids. Although Mercury is darker than the average lunar nearside, the calculated geometric albedo (reflectance at zero phase) is higher for Mercury than the Moon, implying a greater opposition-surge magnitude. The geometric albedo, coupled with the lower reflectance of immature (younger) units on Mercury compared with immature units on the Moon, indicates more heterogeneous grains (marked by variations in composition and structure to produce more scattering centers) within Mercury’s regolith, implying differences in the maturation processes and products between Mercury and the Moon. Ion and micrometeoroid bombardment are the dominant maturation processes on lunar and asteroid surfaces, but each matures the surface at different rates and affects regolith grain characteristics (size, shape, and composition) in different manners. Photometric analysis provides insight into regolith grain properties on Mercury and can help resolve signatures of distinct maturation processes.

Domingue, D.; Vilas, F.; Holsclaw, G. M.; Warell, J.; Izenberg, N. R.; Murchie, S. L.; Denevi, B. W.; Blewett, D. T.; McClintock, W. E.

2009-12-01

190

Metal-hydride transformation kinetics in Mg nanoparticles  

NASA Astrophysics Data System (ADS)

The hydrogen sorption kinetics of magnesium nanoparticles prepared by inert gas condensation and coated by a magnesium oxide layer were investigated by a volumetric apparatus. The metal-hydride transformation was studied by transmission electron microscopy of the nanoparticles both in the as-prepared state and after hydrogen cycling. In small nanoparticles (~35 nm) hydride formation proceeds by one-dimensional growth controlled by diffusion through the hydride, while the reverse transformation to metal involves interface-controlled three-dimensional growth of nuclei formed at constant rate. Large nanoparticles (~450 nm) exhibit very low reactivity attributed to reduced probability of hydrogen dissociation/recombination and nucleation at the particle surface.

Pasquini, L.; Callini, E.; Piscopiello, E.; Montone, A.; Antisari, M. Vittori; Bonetti, E.

2009-01-01

191

Identification and characterization of a new zirconium hydride.  

PubMed

Zirconium alloys are currently used in nuclear power plants where they are susceptible to hydrogen pick-up. Hydride precipitation may occur when the hydrogen solubility limit is reached. Various Zr hydride phases, gamma, delta and epsilon have been identified since the 1950s. Combining electron precession microdiffraction, electron energy loss spectroscopy and ab initio electronic calculations, a new Zr hydride named zeta has been identified and characterized. It belongs to the trigonal crystal system with space group P3 m1 and it is fully coherent with the alphaZr matrix. PMID:19094018

Zhao, Z; Morniroli, J-P; Legris, A; Ambard, A; Khin, Y; Legras, L; Blat-Yrieix, M

2008-12-01

192

Determination of mercurous chloride and total mercury in mercury ores  

USGS Publications Warehouse

A method for the determination of mercurous chloride and total mercury on the same sample is described. The mercury minerals are volatilized in a glass tube and brought into intimate contact with granulated sodium carbonate. The chlorine is fixed as sodium chloride, determined with silver nitrate, and computed to mercurous chloride. The mercury is collected on a previously weighed gold coil and weighed.

Fahey, J. J.

1937-01-01

193

Chemical Hydride Slurry for Hydrogen Production and Storage  

SciTech Connect

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

McClaine, Andrew W.

2008-09-30

194

ENVIRONMENTAL REACTIVITY OF SOLID STATE HYDRIDE MATERIALS  

SciTech Connect

In searching for high gravimetric and volumetric density hydrogen storage systems, it is inevitable that higher energy density materials will be used. In order to make safe and commercially acceptable condensed phase hydrogen storage systems, it is important to understand quantitatively the risks involved in using and handling these materials and to develop appropriate mitigation strategies to handle potential material exposure events. A crucial aspect of the development of risk identification and mitigation strategies is the development of rigorous environmental reactivity testing standards and procedures. This will allow for the identification of potential risks and implementation of risk mitigation strategies. Modified testing procedures for shipping air and/or water sensitive materials, as codified by the United Nations, have been used to evaluate two potential hydrogen storage materials, 2LiBH{sub 4} {center_dot} MgH{sub 2} and NH{sub 3}BH{sub 3}. The modified U.N. procedures include identification of self-reactive substances, pyrophoric substances, and gas-emitting substances with water contact. The results of these tests for air and water contact sensitivity will be compared to the pure material components where appropriate (e.g. LiBH{sub 4} and MgH{sub 2}). The water contact tests are divided into two scenarios dependent on the hydride to water mole ratio and heat transport characteristics. Air contact tests were run to determine whether a substance will spontaneously react with air in a packed or dispersed form. In the case of the 2LiBH{sub 4} {center_dot} MgH{sub 2} material, the results from the hydride mixture compared to the pure materials results showed the MgH{sub 2} to be the least reactive component and LiBH{sub 4} the more reactive. The combined 2LiBH{sub 4} {center_dot} MgH{sub 2} resulted in a material having environmental reactivity between these two materials. Relative to 2LiBH{sub 4} {center_dot} MgH{sub 2}, the chemical hydride NH{sub 3}BH{sub 3} was observed to be less environmentally reactive.

Gray, J; Donald Anton, D

2009-04-23

195

The Hydriding Kinetics of Organic Hydrogen Getters  

SciTech Connect

The aging of hermetically sealed systems is often accompanied by the gradual production of hydrogen gas that is a result of the decay of environmental gases and the degradation of organic materials. In particular, the oxygen, water, hydrogen ''equilibrium'' is affected by the removal of oxygen due the oxidation of metals and organic materials. This shift of the above ''equilibrium'' towards the formation of hydrogen gas, particularly in crevices, may eventually reach an explosive level of hydrogen gas or degrade metals by hydriding them. The latter process is generally delayed until the oxidizing species are significantly reduced. Organic hydrogen getters introduced by Allied Signal Aerospace Company, Kansas City Division have proven to be a very effective means of preventing hydrogen gas accumulation in sealed containers. These getters are relatively unaffected by air and environmental gases. They can be packaged in a variety of ways to fit particular needs such as porous pellets, fine or coarse [gravel] powder, or loaded into silicone rubber. The hydrogen gettering reactions are extremely irreversible since the hydrogen gas is converted into an organic hydrocarbon. These getters are based on the palladium-catalyzed hydrogenation of triple bonds to double and then single bonds in aromatic aryl compounds. DEB (1,4 bis (phenyl ethynyl) benzene) typically mixed with 25% by weight carbon with palladium (1% by weight of carbon) is one of the newest and best of these organic hydrogen getters. The reaction mechanisms are complex involving solid state reaction with a heterogeneous catalyst leading to the many intermediates, including mixed alkyl and aryl hydrocarbons with the possibilities of many isomers. The reaction kinetics mechanisms are also strongly influenced by the form in which they are packaged. For example, the hydriding rates for pellets and gravel have a strong dependence on reaction extent (i.e., DEB reduction) and a kinetic order in pressure of 0.76. Silicone rubber based DEB getters hydride at a much lower rate, have little dependence on reaction extent, have a higher kinetic order in pressure (0.87), and have a lower activation energy. The kinetics of the reaction as a function of hydrogen pressure, stoichiometry, and temperature for hydrogen and deuterium near ambient temperature (0 to 75 C) for pressures near or below 100 Pa over a wide range (in some cases, the complete) hydrogenation range are presented along with multi-dimensional rate models.

Powell, G. L.

2002-02-11

196

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.

2009-05-22

197

Sensing Mercury for Biomedical and Environmental Monitoring  

PubMed Central

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.

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

2009-01-01

198

MERCURY IN MARINE LIFE DATABASE  

EPA Science Inventory

The purpose of the Mercury in Marine Life Project is to organize information on estuarine and marine species so that EPA can better understand both the extent of monitoring for mercury and level of mercury contamination in the biota of coastal environments. This report follows a ...

199

Biogeochemistry: Mercury methylation made easy  

NASA Astrophysics Data System (ADS)

The exact mechanism used by microorganisms to produce the neurotoxin methyl mercury is unclear. The latest laboratory studies point to the amino acid cysteine as an important aid for the uptake of inorganic mercury and its transformation to methyl mercury in Geobacter sulfurreducens.

Sparling, Richard

2009-02-01

200

Mercury intoxication presenting with tics  

PubMed Central

A 5 year old Chinese boy presented with recurrent oral ulceration followed by motor and vocal tics. The Chinese herbal spray he used for his mouth ulcers was found to have a high mercury content. His blood mercury concentration was raised. Isolated tics as the sole presentation of mercury intoxication has not previously been reported.??

Li, A.; Chan, M.; Leung, T; Cheung, R.; Lam, C.; Fok, T

2000-01-01

201

ATMOSPHERIC MERCURY TRANSPORT AND DEPOSITION  

EPA Science Inventory

The current state of our scientific understanding the mercury cycle tells us that most of the mercury getting into fish comes from atmospheric deposition, but methylation of that mercury in aquatic systems is required for the concentrations in fish to reach harmful levels. We st...

202

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...

203

Hydrogen storage in sodium aluminum hydride.  

SciTech Connect

Sodium aluminum hydride, NaAlH{sub 4}, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the NaAlH{sub 4} and Na{sub 3}AlH{sub 6} structures are complex-ionic hydrides with Na{sup +} cations and AlH{sub 4}{sup -} and AlH{sub 6}{sup 3-} anions, respectively. Compound formation studies indicate the primary Ti-compound formed when doping the material at 33 at. % is TiAl{sub 3} , and likely Ti-Al compounds at lower doping rates. A general study of sorption kinetics of NaAlH{sub 4}, when doped with a variety of Ti-halide compounds, indicates a uniform response with the kinetics similar for all dopants. NMR multiple quantum studies of solution-doped samples indicate solvent interaction with the doped alanate. Raman spectroscopy was used to study the lattice dynamics of NaAlH{sub 4}, and illustrated the molecular ionic nature of the lattice as a separation of vibrational modes between the AlH{sub 4}{sup -} anion-modes and lattice-modes. In-situ Raman measurements indicate a stable AlH{sub 4}{sup -} anion that is stable at the melting temperature of NaAlH{sub 4}, indicating that Ti-dopants must affect the Al-H bond strength.

Ozolins, Vidvuds; Herberg, J.L. (Lawrence Livermore National Laboratories, Livermore, CA); McCarty, Kevin F.; Maxwell, Robert S. (Lawrence Livermore National Laboratories, Livermore, CA); Stumpf, Roland Rudolph; Majzoub, Eric H.

2005-11-01

204

Isotope effects on hydride transfer reactions from transition metal hydrides to trityl cation. An inverse isotope effect for a hydride transfer  

SciTech Connect

Kinetic isotope effects are useful in mechanistic studies, since they can provide insight into the transition state of the reaction being examined. Hydride (H{sup {minus}}) transfer reactions between carbons are pertinent to the chemistry of nicotinamide adenine dinucleotide (NAD{sup +}) analogues. Kinetic and mechanistic studies have established details of hydride transfers from 1,4-dihydropyridines and related hydride donors to carbon-based hydride acceptors such as pyridinium or acridinium cations. Hydride transfer from transition metal hydrides (MH) to Ph{sub 3}C{sup +}BF{sub 4}{sup {minus}} gives M-FBF{sub 3} and Ph{sub 3}CH. Deuterium kinetic isotope effects were determined for several MH/MD pairs (CH{sub 2}Cl solution, 25 C). For hydride transfer from Cp*(CO){sub 3}MoH (Cp{sup *} = {eta}{sup 5}-C{sub 5}Me{sub 5}) to substituted trityl cations containing zero, one, two, or three p-MeO groups [Ph{sub n}(p-MeOC{sub 6}H{sub 4}){sub 3{minus}n}C{sup +}BF{sub 4}{sup {minus}}; n = 3, 2, 1, 0], the isotope effect remains essentially constant at k{sub MoH}/k{sub MoD} = 1.7--1.9 as the rate constant decreases from k{sub H{sup {minus}}} = 6.5 {times} 10{sup 3} to 1.4 M{sup {minus}1} s{sup {minus}1}. For hydride transfer to Ph{sub 3}C{sup +}BF{sub 4}{sup {minus}} from five metal hydrides [Cp(CO){sub 3}MoH, Cp{sup *}(CO){sub 3}WH, (indenyl)(CO){sub 3} WH, Cp{sup *}(CO){sub 3}MoH, and trans-Cp(CO){sub 2}(PCy{sub 3})MoH; Cp = {eta}{sup 5}-C{sub 5}H{sub 5}] with second-order rate constants k{sub H{sup {minus}}} {ge} 3.8 {times} 10{sup 2} M{sup {minus}1} s{sup {minus}1}, the kinetic isotope effects are also k{sub MH}/k{sub MD} = 1.7--1.8. For a series of five tungsten hydrides with substituted Cp ligands, the kinetic isotope effects decrease from k{sub WH}/k{sub WD} = 1.8 to 0.47 as the rate constant decreases (from k{sub H{sup {minus}}} = 2.0 {times} 10{sup 3} to 0.72 M{sup {minus}1} s{sup {minus}1}). The steadily decreasing values of k{sub MH}/k{sub MD} with decreasing rate constants of hydride transfer are interpreted as indicating progressively stronger force constants of isotopically sensitive modes of the transition state, as the reaction slows down in progressing from more electron-donating Cp ligands to less electron-rich Cp ligands. The inverse isotope effect (k{sub WH}/k{sub WD} = 0.47) found for the slowest tungsten hydride, (C{sub 5}H{sub 4}CO{sub 2}Me)(CO){sub 3}WH, is proposed to be due to a product-like transition state for irreversible hydride transfer.

Cheng, T.Y.; Bullock, R.M. [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.

1999-04-07

205

Materials science of Mg-Ni-based new hydrides  

NASA Astrophysics Data System (ADS)

One of the advantageous functional properties of Mg alloys (or compounds) is to exhibit the reversible hydriding reaction. In this paper, we present our systematic studies regarding the relationship between nanometer- or atomistic-scale structures 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) n-MgNi2. Further studies on(5) an a-MgNi-based system for clarifying the effect of the short-range ordering on the structural and hydriding properties and(6) a MgNi2-based system for synthesizing the new Laves phase structure are also presented. The materials science of Mg-Ni-based new hydrides will provide indispensable knowledge for practically developing the Mg alloys as hydrogen-storage materials.

Orimo, S.; Fujii, H.

2001-04-01

206

Two-Step Hydride Shift to Aryl Carbonium Ions.  

National Technical Information Service (NTIS)

A typical reaction of carbonium ions is the hydride shift from hydrocarbons. Mechanisms have been suggested where the shift is regarded as a one-step process. The authors report that perchlorodiphenylcarbonium hexa-chloroantimonate reacts with cycloheptat...

A. Rodriguez-Siurana J. Castaner J. Riera-Figueras M. Ballester

1971-01-01

207

Galvanic corrosion test measurements zircaloy process tube hydriding problem.  

National Technical Information Service (NTIS)

In September of 1965, a program was launched to investigate the cause and to determine appropriate corrective or preventive action for hydriding of Zircaloy process tubes in K Reactors. One phase of the investigation was specifically directed to the measu...

W. R. Thorson

1967-01-01

208

Nonaqueous actinide hydride dissolution and production of actinide $beta$- diketonates  

DOEpatents

Actinide beta-diketonate complex molecular compounds are produced by reacting a beta-diketone compound with a hydride of the actinide material in a mixture of carbon tetrachloride and methanol. (auth)

Crisler, L.R.

1975-11-11

209

Thermally unstable hydrides of titanium aluminide Ti3Al  

NASA Astrophysics Data System (ADS)

The hydrogen capacity of (Ti, Nb)3Al titanium aluminides subjected to mechanical activation in a hydrogen atmosphere has been studied. It has been shown that the application of this procedure allows one to prepare thermally unstable titanium aluminide (Ti3Al) hydrides with a high hydrogen content (to 2.6 wt %) at room temperature and normal pressure; in this case, no special requirements for the hydrogen purity are placed. The thermally unstable nanostructured Ti3Al hydrides were found to exhibit a higher hydrogen mobility as compared to that of the microcrystalline hydrides. Low niobium additions (to 2.1 at %) have been found to decrease the hydrogen capacity. Experiments on the preparation of bulk samples from the hydride powders obtained were performed.

Kazantseva, N. V.; Popov, A. G.; Mushnikov, N. V.; Skripov, A. V.; Soloninin, A. V.; Aleksashin, B. A.; Novozhenov, V. I.; Sazonova, V. A.; Kharisova, A. G.

2011-04-01

210

Methods and Apparatus for Synthesis of Metal Hydrides.  

National Technical Information Service (NTIS)

An electrochemical process and apparatus for preparing metal hydride compounds from metal salts under a hydrogen atmosphere are disclosed. The electrochemical process may be integrated with chemical reaction of a boron compound to produce borohydride comp...

M. T. Kelly

2005-01-01

211

Self-Consistent-Field Calculation on Lithium Hydride for Undergraduates.  

ERIC Educational Resources Information Center

|Describes a self-consistent-field-linear combination of atomic orbitals-molecular orbital calculation on the valence electrons of lithium hydride using the method of Roothaan. This description is intended for undergraduate physics students.|

Rioux, Frank; Harriss, Donald K.

1980-01-01

212

Synthesis and characterization of metal hydride electrodes. Interim report.  

National Technical Information Service (NTIS)

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 hydr...

J. McBreen J. J. Reilly

1995-01-01

213

The development of lightweight hydride alloys based on magnesium  

SciTech Connect

The development of a magnesium based hydride material is explored for use as a lightweight hydrogen storage medium. It is found that the vapor transport of magnesium during hydrogen uptake greatly influences the surface and hydride reactions in these alloys. This is exploited by purposely forming near-surface phases of Mg{sub 2}Ni on bulk Mg-Al-Zn alloys which result in improved hydrogen adsorption and desorption behavior. Conditions were found where these near-surface reactions yielded a complex and heterogeneous microstructure that coincided with excellent bulk hydride behavior. A Mg-Al alloy hydride is reported with near atmospheric plateau pressures at temperatures below 200{degrees}C. Additionally, a scheme is described for low temperature in-situ fabrication of Mg{sub 2}Ni single phase alloys utilizing the high vapor pressure of Mg.

Guthrie, S.E.; Thomas, G.J.; Yang, N.Y.C.; Bauer, W. [Sandia National Labs., Livermore, CA (United States)

1996-02-01

214

Observations on the Zirconium Hydride Precipitation and Distribution in Zircaloy-4  

NASA Astrophysics Data System (ADS)

Hydride precipitation and distribution in hot-rolled and annealed Zircaloy-4 plate samples artificially induced by gaseous hydrogen charging were studied primarily by neutron tomography, scanning electron microscopy (SEM), and SEM-based electron backscattered diffraction techniques. The precipitated hydride platelet (?-ZrH1.66) at a hydrogen pressure of 20 atm was found following the {111} ?-ZrH1.66//(0001) ?-Zr with the surrounding ?-Zr matrix. The microstructural characterization indicated that hydrides with a relatively uniform distribution were precipitated on the rolling-transverse section of the plate, whereas, on the normal-transverse section, a hydride concentration gradient was present with a dense hydride layer near the surface. Further, the neutron tomography investigations clearly identified the nonuniform spatial distribution of hydrides. Thin hydride layers preferentially formed on the sample surface, and the concentrated hydrides precipitating at the edges/corner of the sample were observed. The causes for the localized hydride accumulation were also discussed.

Wang, Zhiyang; Garbe, Ulf; Li, Huijun; Harrison, Robert P.; Kaestner, Anders; Lehmann, Eberhard

2013-05-01

215

Pyrophoric behaviour of uranium hydride and uranium powders  

Microsoft Academic Search

Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (<0.5wt.%) was obtained by heat treatment at low temperature in flowing Ar\\/5%H2. Pure uranium powder was

F. Le Guyadec; X. Génin; J. P. Bayle; O. Dugne; A. Duhart-Barone; C. Ablitzer

2010-01-01

216

Potential energy surfaces for the uranium hydriding reaction  

Microsoft Academic Search

We have computed the potential energy surfaces for the low-lying electronic states of uranium hydrides, UHn (n=1-3), which are important in the uranium hydriding reactions. We have employed a number of computational methods including the complete active space multiconfiguration self-consistent field followed by multireference relativistic configuration interaction computations with spin-orbit coupling that included up to 6 million configurations. We find

K. Balasubramanian; Wigbert J. Siekhaus; William McLean II

2003-01-01

217

Ab-Initio Study of the Group 2 Hydride Anions  

NASA Astrophysics Data System (ADS)

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)

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

2013-06-01

218

Out-of-pile accelerated hydriding of Zircaloy fasteners  

Microsoft Academic Search

Mechanical joints between Zircaloy and nickel-bearing alloys, mainly the Zircaloy-4\\/Inconel-600 combination, were exposed to water at 450°F and 520°F to study hydriding of Zircaloy in contact with a dissimilar metal. Accelerated hydriding of the Zircaloy occurred at both temperatures. At 450°F the dissolved hydrogen level of the water was over ten times that at 520°F. At 520°F the initially high

1979-01-01

219

Development of the Low-Pressure Hydride/Dehydride Process  

SciTech Connect

The low-pressure hydride/dehydride process was developed from the need to recover thin-film coatings of plutonium metal from the inner walls of an isotope separation chamber located at Los Alamos and to improve the safety operation of a hydride recovery process using hydrogen at a pressure of 0.7 atm at Rocky Flats. This process is now the heart of the Advanced Recovery and Integrated Extraction System (ARIES) project.

Rueben L. Gutierrez

2001-04-01

220

Temperature-Dependent Electronic Transition in Cerium Hydride  

Microsoft Academic Search

Resistivity measurements of single crystals of cerium hydride as a function of temperature revealed resistivity anomalies at about 250°K, which may be associated with a previously reported compositional metal-to-semiconductor transition. Precise x-ray diffractiometry disclosed that the cubic fluorite type structure of cerium hydride becomes slightly tetragonal below 250°K. Neutron-diffraction investigations showed no apparent ordering of excess hydrogen atoms in octahedral

G. G. Libowitz; J. G. Pack; W. P. Binnie

1972-01-01

221

THE CRYSTAL STRUCTURE AND DENSITY OF CERIUM HYDRIDES  

Microsoft Academic Search

The structure and density of cerium hydrides of CeH\\/sub o\\/ CeHâ ; composition were studied. Two phases were present in metallic cerium and its ; dihydrides (Ce--CeHâ. A negligible change in the lattice period from 5.55 ; A to 5.53 A for CeH\\/sub 2.73\\/ was observed for CeHâ- CeHâ. The ; cerium hydride density curve is at its minimum for

M. E. Kost; G. A. Golder

1959-01-01

222

Observations of Mercury’s Exosphere from MESSENGER: An Overview  

NASA Astrophysics Data System (ADS)

The Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission began routine orbital observations of both the dayside and nightside exosphere on March 29, 2011. We have accumulated more than 9 Mercury years of exosphere data covering all local times; those observations allow statistical analyses of both seasonal and local-time variability of key components of Mercury’s near-surface exosphere: sodium, calcium, and magnesium. An overview of the UVVS exospheric observations highlights the balance between observing scenarios from orbit and challenges we have encountered retrieving exosphere composition and structure. MESSENGER’s UVVS offers an exciting potential for observing the near-surface exosphere above Mercury’s hollows, as well as the comas and tails of comets C/2012 S1 (ISON) and 2P/Encke as they fly by the innermost planet.

Merkel, Aimee; McClintock, W.; Vervack, R.; Cassidy, T.; Burger, M.; Killen, R.; Sarantos, M.

2013-10-01

223

Enhanced mercury oxidation  

SciTech Connect

A new catalyst offers a new way to enhance mercury control from bituminous coal-fired power plants. Hitachi has developed an SCR catalyst which satisfies high Hg{sup 0} oxidation and low SO{sub 2} oxidation requirements under high temperatures (716 to 770 F). This triple action catalysts, TRAC can significantly enhance mercury oxidation and reduce or eliminate the need for additional mercury control measures such as activated carbon injection. After laboratory testing, pilot-scale tests confirmed an activity of 1.4-1.7 times higher than that of conventional SCR catalyst. The new catalyst has been successfully applied in a commercial PRB-fired boiler without the need for halogens to be added to the fuel feed or flue gas. 2 figs.

Gretta, W.J.; Wu, S.; Kikkawa, H. [Hitachi Power Systems America, Basting Ridge, NJ (United States)

2009-06-15

224

Follow that mercury!  

SciTech Connect

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.

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

2008-07-01

225

Hydride-containing molten salts and their technology implications  

NASA Astrophysics Data System (ADS)

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.

Liaw, Bor Y.

1993-03-01

226

AIR PASSIVATION OF METAL HYDRIDE BEDS FOR WASTE DISPOSAL  

SciTech Connect

Metal hydride beds offer compact, safe storage of tritium. After metal hydride beds have reached the end of their useful life, the beds will replaced with new beds and the old beds prepared for disposal. One acceptance criteria for hydride bed waste disposal is that the material inside the bed not be pyrophoric. To determine the pyrophoric nature of spent metal hydride beds, controlled air ingress tests were performed. A simple gas handling manifold fitted with pressure transducers and a calibrated volume were used to introduce controlled quantities of air into a metal hydride bed and the bed temperature rise monitored for reactivity with the air. A desorbed, 4.4 kg titanium prototype hydride storage vessel (HSV) produced a 4.4 C internal temperature rise upon the first air exposure cycle and a 0.1 C temperature rise upon a second air exposure. A total of 346 scc air was consumed by the bed (0.08 scc per gram Ti). A desorbed, 9.66 kg LaNi{sub 4.25}Al{sub 0.75} prototype storage bed experienced larger temperature rises over successive cycles of air ingress and evacuation. The cycles were performed over a period of days with the bed effectively passivated after the 12th cycle. Nine to ten STP-L of air reacted with the bed producing both oxidized metal and water.

Klein, J; R. H. Hsu, R

2007-07-02

227

Metallographic and fractographic observations of hydrides during delayed hydride cracking in Zr-2.5% Nb alloy  

SciTech Connect

Potential drop measurements, optical microscopy, and scanning electron microscopy were performed to study the mechanism of delayed hydride cracking (DHC), the relation of the fracture to the hydride morphology, and the fractography of the DHC mechanism. The material used in this study was taken from modified extrusions of the material used to manufacture Zr-2.5% Nb pressure tubes. The material was electrolytically hydrided to approximately 60 {micro}g/g before testing. Cracking tests were carried out at 250 C with an applied K{sub 1} of 12 MPa {radical}m. The number of potential jumps was strongly correlated to the number of striations on the fracture surface. The results indicate that the DHC process occurs in these samples in an intermittent fashion. Brittle fracture is the operating fracture mechanism for the hydrides that cover most of the fracture surface, but there are some regions of ductile fracture both within the fracture and at the striations.

Jovanovic, M.T.; Eadie, R.L. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering; Shek, G.K.; Seahra, H. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

1998-01-01

228

Mercury Transport in Bacteria  

Microsoft Academic Search

Mercuric ions (Hg2+) and methylmercury are major, human-generated, toxic contaminants present in fish and our waterways. Bacteria provide a means\\u000a of bioremediation by taking up these compounds and reducing them to volatile, non-toxic, elemental mercury (Hg°). Three types\\u000a of mercury\\/methylmercury transporters have previously been identified: MerC, MerF and MerT. Each of these sets of homologues\\u000a has distinct topologies. MerF proteins

Ai Yamaguchi; Dorjee G. Tamang; Milton H. Saier Jr

2007-01-01

229

US EPA: Mercury  

NSDL National Science Digital Library

Visitors to this Web site from the US Environmental Protection Agency can learn about the ecological and health concerns associated with mercury. In addition to the resources available on the main Web page, the site also contains a teaching guide. Educators are invited to help "students learn about the health and environmental concerns associated with mercury, find out where it is in their school and homes, and help school officials and family members do something about it." The activities are designed for high school students, but could be modified for younger students.

230

Mercury and mercury compounds toxicology. (Latest citations from the Life Sciences Collection data base). Published Search  

SciTech Connect

The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. Mercury metal, mercury vapors, organic mercury compounds, mercury halides, and other inorganic mercury compounds are discussed. Citations include acute, chronic, environmental, metabolic, and pathological effects; and clinical biochemistry of mercury exposure. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1992-10-01

231

Mercury and mercury compounds toxicology. (Latest citations from the Life Sciences Collection database). Published Search  

SciTech Connect

The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. Mercury metal, mercury vapors, organic mercury compounds, mercury halides, and other inorganic mercury compounds are discussed. Citations include acute, chronic, environmental, metabolic, and pathological effects; and clinical biochemistry of mercury exposure. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1994-04-01

232

Mercury's Dynamic Magnetic Tail (Invited)  

NASA Astrophysics Data System (ADS)

The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The sources of the great dynamic variability observed during these brief flybys certainly include Mercury’s proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet’s lack of an ionosphere and its small physical dimensions also contribute. In particular, Mercury’s very brief Dungey cycle, ~ 2 min, which governs the time scale for internal plasma circulation, allows for very rapid transitions to new equilibrium states. Current observations and understanding of the structure and dynamics of Mercury’s magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury’s tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

Slavin, J. A.

2010-12-01

233

Mercury speciation into tropospheric clouds  

NASA Astrophysics Data System (ADS)

Cloud water bas been sampled at the Puy De Dôme (France) for mercury determination. The analysis of these samples gave us concentrations from about 10 to 50 ng/L and from about 0.8 to 3.5 ng/L for total mercury (HgT) and for reactive mercury (HgR) respectively. In a previous study based on analysis of Total Gaseous Mercury in the interstitial phase of clouds, mercury concentrations in cloud water were estimated to be around 1 ?g/L. Comparing this assumption with our measurements, we suggest that Hg'could be the principal mercury species in cloud water. A kinetic study, which compares reduction and oxidation processes, supports our hypothesis. Assuming our assumption to be tme, precipitation is likely to contribute significantly to elemental mercury deposition.

Gauchard, P.-A.; Dommergue, A.; Ferrari, C. P.; Laj, P.; Boutron, C. F.

2003-05-01

234

Method and apparatus for sampling atmospheric mercury  

DOEpatents

A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

Trujillo, Patricio E. (Santa Fe, NM); Campbell, Evan E. (Los Alamos, NM); Eutsler, Bernard C. (Los Alamos, NM)

1976-01-20

235

Biological Methylation of Mercury in Aquatic Organisms  

Microsoft Academic Search

FRESHWATER fish, especially pike (Esox lucius), from Sweden sometimes contain abnormally large amounts of mercury1. It was initially concluded to be either inorganic mercury or phenyl mercury, which are known to be released as industrial wastes, but later it was shown that the mercury was present almost entirely as methyl mercury (CH3Hg+)2. A possible explanation is that living organisms have

S. Jensen; A. JERNELÖV

1969-01-01

236

Isolation of a mixed valence diiron hydride: evidence for a spectator hydride in hydrogen evolution catalysis.  

PubMed

The mixed-valence diiron hydrido complex (?-H)Fe2(pdt)(CO)2(dppv)2 ([H1](0), where pdt =1,3-propanedithiolate and dppv = cis-1,2-C2H2(PPh2)2), was generated by reduction of the differous hydride [H1](+) using decamethylcobaltocene. Crystallographic analysis shows that [H1](0) retains the stereochemistry of its precursor, where one dppv ligand spans two basal sites and the other spans apical and basal positions. The Fe---Fe bond elongates to 2.80 from 2.66 Å, but the Fe-P bonds only change subtly. Although the Fe-H distances are indistinguishable in the precursor, they differ by 0.2 Å in [H1](0). The X-band electron paramagnetic resonance (EPR) spectrum reveals the presence of two stereoisomers, the one characterized crystallographically and a contribution of about 10% from a second symmetrical (sym) isomer wherein both dppv ligands occupy apical-basal sites. The unsymmetrical (unsym) arrangement of the dppv ligands is reflected in the values of A((31)P), which range from 31 MHz for the basal phosphines to 284 MHz for the apical phosphine. Density functional theory calculations were employed to rationalize the electronic structure of [H1](0) and to facilitate spectral simulation and assignment of EPR parameters including (1)H and (31)P hyperfine couplings. The EPR spectra of [H1](0) and [D1](0) demonstrate that the singly occupied molecular orbital is primarily localized on the Fe center with the longer bond to H, that is, Fe(II)-H···Fe(I). The coupling to the hydride is A((1)H) = 55 and 74 MHz for unsym- amd sym-[H1](0), respectively. Treatment of [H1](0) with H(+) gives 0.5 equiv of H2 and [H1](+). Reduction of D(+) affords D2, leaving the hydride ligand intact. These experiments demonstrate that the bridging hydride ligand in this complex is a spectator in the hydrogen evolution reaction. PMID:23383865

Wang, Wenguang; Nilges, Mark J; Rauchfuss, Thomas B; Stein, Matthias

2013-02-21

237

Mercury and New Impoundments.  

National Technical Information Service (NTIS)

Two small reservoirs were used in an investigation to determine the concentrations of mercury in the impounded water as each basin filled. There was an initial sampling of soil and plant specimens from the pre-flooded reservoir sites to establish backgrou...

C. M. Weiss A. E. Bond

1978-01-01

238

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...

239

Acute mercurial pneumonitis  

PubMed Central

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.

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

1970-01-01

240

Mercury and Venus  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

241

Hazards of Mercury.  

ERIC Educational Resources Information Center

|Common concern for the protection and improvement of the environment and the enhancement of human health and welfare underscore the purpose of this special report on the hazards of mercury directed to the Secretary's Pesticide Advisory Committee, Department of Health, Education, and Welfare. The report summarizes the findings of a ten-member…

Environmental Research, 1971

1971-01-01

242

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 ...

243

MERCURY CYCLING AND BIOMAGNIFICATION  

EPA Science Inventory

Mercury cycling and biomagnification was studied in man-made ponds designed for watering livestock on the Cheyenne River Sioux Reservation in South Dakota. Multiple Hg species were quantified through multiple seasons for 2 years in total atmospheric deposition samples, surface wa...

244

Mercury Information Clearinghouse  

SciTech Connect

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.

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

245

Feasibility of Improving BWR Performance Using Hydride Fuel  

SciTech Connect

Neutronic and thermal-hydraulic analyses have been performed for U-ZrH{sub 1.6} hydride fueled BWR cores considering a wide range of core design variables: (1) Fuel rod outer diameter in the range from 0.6 to 1.6 cm; (2) Lattice pitch-to-diameter ratio, P/D: 1.1 to 1.6; (3) Several uranium enrichment levels. The design constraints considered include minimum excess reactivity, negative Doppler coefficient, negative void coefficient, MCPR, peak and average fuel temperatures, peak clad surface temperature, coolant inlet temperature, coolant exit quality, coolant pressure drop, as well as constraints imposed by vibrations and structural considerations. It was found that U-ZrH1.6 fuel can significantly simplify the BWR fuel bundle design by eliminating water rods, partial-length fuel rods and wide water channels and by using a single radial enrichment. A 10 x 10 hydride fuel bundle having the volume of the reference 9 x 9 oxide fuel bundle can be loaded with 35% more fuel rods having a similar diameter and lattice pitch. As a result of this along with flatter pin-by-pin power distribution the hydride fuel bundle can deliver {approx} 40% higher power density than the reference oxide fuel bundle, provided the core coolant pressure drop could be increased by {approx} 50%. Alternatively, the hydride fuelled core can be designed not to exceed the reference BWR core pressure drop and to deliver the reference power while using {approx} 40% shorter fuel bundles. The hydride fuelled core has a more negative fuel temperature coefficient of reactivity and a less negative void coefficient of reactivity. These trends are expected to enhance the safety and improve the stability of hydride fueled BWRs. A thorough evaluation of hydride fuel and its implementation possibilities in BWRs is recommended. (authors)

Fratoni, M.; Ginex, F.; Ganda, F.; Greenspan, E. [University of California, Berkeley, CA 94720 (United States); Ferroni, P.; Handwerk, C.; Todreas, N. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2006-07-01

246

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...

247

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...

248

Mercury control in 2009  

SciTech Connect

Although activated carbon injection (ACI) has been proven to be effective for many configurations and is a preferred option at many plants sufficient quantities of powdered activated coking (PAC) must be available to meet future needs. The authors estimate that upcoming federal and state regulations will result in tripling the annual US demand for activated carbon to nearly 1.5 billion lb from approximately 450 million lb. Rapid expansion of US production capacity is required. Many PAC manufacturers are discussing expansion of their existing production capabilities. One company, ADA Carbon Solutions, is in the process of constructing the largest activated carbon facility in North America to meet the future demand for PAC as a sorbent for mercury control. Emission control technology development and commercialization is driven by regulation and legislation. Although ACI will not achieve > 90% mercury control at every plant, the expected required MACT legislation level, it offers promise as a low-cost primary mercury control technology option for many configurations and an important trim technology for others. ACI has emerged as the clear mercury-specific control option of choice, representing over 98% of the commercial mercury control system orders to date. As state regulations are implemented and the potential for a federal rule becomes more imminent, suppliers are continuing to develop technologies to improve the cost effectiveness and limit the balance of plant impacts associated with ACI and are developing additional PAC production capabilities to ensure that the industry's needs are met. The commercialisation of ACI is a clear example of industry, through the dedication of many individuals and companies with support from the DOE and EPRI, meeting the challenge of developing cost-effectively reducing emissions from coal-fired power plants. 7 refs., 1 fig.

Sjostrom, S.; Durham, M.; Bustard, J.; Martin, C. [ADA Environmental Solutions, Littleton, CO (United States)

2009-07-15

249

Evolution of Mercury's obliquity  

NASA Astrophysics Data System (ADS)

Mercury has a near-zero obliquity, i.e. its spin axis is nearly perpendicular to its orbital plane. The value of the obliquity must be known precisely in order to constrain the size of the planet's core within the framework suggested by Peale [Peale, S.J., 1976. Nature 262, 765-766]. Rambaux and Bois [Rambaux, N., Bois, E., 2004. Astron. Astrophys. 413, 381-393] have suggested that Mercury's obliquity varies on thousand-year timescales due to planetary perturbations, potentially ruining the feasibility of Peale's experiment. We use a Hamiltonian approach (free of energy dissipation) to study the spin-orbit evolution of Mercury subject to secular planetary perturbations. We can reproduce an obliquity evolution similar to that of Rambaux and Bois [Rambaux, N., Bois, E., 2004. Astron. Astrophys. 413, 381-393] if we integrate the system with a set of initial conditions that differs from the Cassini state. However the thousand-year oscillations in the obliquity disappear if we use initial conditions corresponding to the equilibrium position of the Cassini state. This result indicates that planetary perturbations do not force short-period, large amplitude oscillations in the obliquity of Mercury. In the absence of excitation processes on short timescales, Mercury's obliquity will remain quasi-constant, suggesting that one of the important conditions for the success of Peale's experiment is realized. We show that interpretation of data obtained in support of this experiment will require a precise knowledge of the spin-orbit configuration, and we provide estimates for two of the critical parameters, the instantaneous Laplace plane orientation and the orbital precession rate from numerical fits to ephemeris data. Finally we provide geometrical relationships and a scheme for identifying the correct initial conditions required in numerical integrations involving a Cassini state configuration subject to planetary perturbations.

Yseboodt, Marie; Margot, Jean-Luc

2006-04-01

250

Gastrointestinal absorption of metallic mercury.  

PubMed

The absorption of mercury from the gastrointestinal systems of 7 subjects, of whom none had any amalgam fillings, was examined in this study. The authors obtained quantitative information about mercury concentration in plasma and duodenal fluid after the gastrointestinal systems of the subjects were exposed to liquid elemental mercury enclosed in rubber balloons (i.e., approximately 20 g of mercury), using a standard procedure followed for the sampling of bile. Plasma samples were collected prior to exposure, as well as up to 10 d following exposure, and duodenal fluid was collected 1 h, 2 h, 4 h, and 6 h during the intubation process. The authors studied the kinetics of dissolution in vitro by leaching elemental liquid mercury and mercuric chloride. The results of this study supported the hypothesis that metallic mercury is oxidized in the gastrointestinal tract. In addition, the authors determined that duodenal intubation, while using liquid metallic mercury in rubber bags, resulted in the diffusion of minor amounts of atomic elemental mercury through the rubber walls. The absorbed amount of mercury that reached the central circulation was comparable to a daily dose of mercury from dental amalgam in the amalgam-bearing population. PMID:16381485

Sandborgh-Englund, Gunilla; Einarsson, Curt; Sandström, Magnus; Ekstrand, Jan

2004-09-01

251

Fatigue crack growth in lithium hydride  

SciTech Connect

Subcritical fatigue crack growth, from cyclic tensile loading, was demonstrated in warm pressed Polycrystalline lithium hydride. Experiments were performed with cyclic tension-tension crack opening (mode I) loads applied to a pre-cracked compact type specimen in an argon environment at a temperature of 21C (70F). The fatigue crack growth was found to occur between 7.56 {times} 10{sup {minus}ll} M/cycle (2.98 {times} l0{sup {minus}9} in/cycle) and 2.35 {times} l0{sup {minus}8} m/cycle (9.24{times}10{sup {minus}7} in/cycle) for a range of stress intensity factors between 1.04 MPa{center_dot}{radical}m (0.95 ksi{center_dot}{radical}in) and 1.49 MPa{center_dot}{radical}m (1.36 ksi{center_dot}{radical}in). The rate of fatigue crack growth from cyclic tensile loading was found to be in excess of crack growth from sustained loading at an equivalent stress intensity factor. Furthermore, a fatigue threshold was not evident from the acquired data.

Healy, T.E.

1993-09-01

252

Hydrides of DyCo/sub 3/  

SciTech Connect

Hydrogen desorption isotherms have been measured in the system DyCo/sub 3/H/sub x/ for 0 less than or equal to x less than or equal to 4.25 at temperatures of 0/sup 0/, 20/sup 0/, 40/sup 0/, 60/sup 0/, and 80/sup 0/C. Pressure plateaus on the isotherms indicate the existence of two hydride phases in addition to the terminal hydrogen-saturated metal ..cap alpha.. phase. Both exhibit a wide range of solid solutions. The ..beta.. phase runs from x = 1 to x = 1.83, while the ..gamma.. phase runs from 3.1 to at least 4.25. The ..cap alpha.. phase is very narrow. At 20/sup 0/C the plateau pressures are 3 torr and 54 torr, and the heats of absorption are -11.43 and -9.75 kcal/mole(H/sub 2/) respectively. From the temperature dependence of the isotherms, the partial molar heats and entropies of absorption and the heats and entropies of formation have been calculated as a function of x.

Kierstead, H.A.

1980-01-01

253

Surface catalyzed mercury transformation reactions  

NASA Astrophysics Data System (ADS)

Mercury is a known pollutant that has detrimental effect on human health and environment. The anthropogenic emissions of mercury account for 10 to 30% of worldwide mercury emissions. There is a need to control/reduce anthropogenic mercury emissions. Many mercury control technologies are available but their effectiveness is dependent on the chemical form of mercury, because different chemical forms of mercury have different physical and chemical properties. Mercury leaves the boiler in its elemental form but goes through various transformations in the post-combustion zone. There is a need to understand how fly ash and flue gas composition affect speciation, partitioning, and reactions of mercury under the full range of post-combustion zone conditions. This knowledge can then be used to predict the chemical transformation of mercury (elemental, oxidized or particulate) in the post combustion zone and thus help with the control of mercury emissions from coal-burning power plants. To accomplish this goal present study was conducted using five coal fly ashes. These ashes were characterized and their catalytic activity was compared under selected reaction conditions in a fixed bed reactor. Based on the results from these fly ash experiments, three key components (carbon, iron oxide and calcium oxide) were chosen. These three components were then used to prepare model fly ashes. Silica/alumina was used as a base for these model fly ashes. One, two or three component model fly ashes were then prepared to investigate mercury transformation reactions. The third set of experiments was performed with five different oxidation catalysts to further understand the mercury oxidation process. Based on the results of these three studies the key components were predicted for different fly ash compositions under variety of flue gas conditions. A fixed bed reactor system was used to conduct this study. In all the experiments, the inlet concentration of Hg0(g) was maintained at 35 mug/m 3 using a diffusion tube as the source of Hg0(g). All experiments were conducted using 4% O2 in nitrogen mix as a reaction gas, and other reactants (HCl, H2O and SO2, NO 2, Br2) were added as required. The fixed bed reactor was operated over a temperature range of 200 to 400°C. In each experiment, the reactor effluent was analyzed using the modified Ontario-Hydro method. After each experiment, fly ash particles were also analyzed for mercury. The results show that the ability of fly ash to adsorb and/or oxidize mercury is primarily dependent on its carbon, iron and calcium content. There can be either one or more than one key component at a particular temperature and flue gas condition. Surface area played a secondary role in effecting the mercury transformations when compared to the concentration of the key component in the fly ash. Amount carbon and surface area played a key important role in the adsorption of mercury. Increased concentration of gases in the flue gas other than oxygen and nitrogen caused decreased the amount of mercury adsorbed on carbon surface. Mercury adsorption by iron oxide primarily depended on the crystalline structure of iron oxide. alpha-iron oxide had no effect on mercury adsorption or oxidation under most of the flue gas conditions, but gamma-iron oxide adsorbed mercury under most of the flue gas conditions. Bromine is a very good oxidizing agent for mercury. But in the presence of calcium oxide containing fly ashes, all the oxidized mercury would be reduced to elemental form. Among the catalysts, it was observed that presence of free lattice chlorine in the catalyst was very important for the oxidation of mercury. But instead of using the catalyst alone, using it along with carbon may better serve the purpose by providing the adsorption surface for mercury and also some extra surface area for the reaction to occur (especially for fly ashes with low surface area).

Varanasi, Patanjali

254

EPA's Roadmap for Mercury, July 2006.  

National Technical Information Service (NTIS)

EPA's Roadmap focuses on six key areas, with the overarching goal of reducing health risks associated with mercury exposure. EPA will reduce risk by: 1. Addressing mercury releases to the environment 2. Addressing mercury uses in products and processes 3....

2006-01-01

255

Metabolism of Mercury Compounds in Microorganisms.  

National Technical Information Service (NTIS)

The report describes the physiology and ecology of mercury-resistant and mercury-metabolizing bacteria from Chesapeake Bay. Evidence is presented which establishes a role for bacteria in the cycling of mercury in the estuarine environment. From the result...

R. R. Colwell J. D. Nelson

1975-01-01

256

Recovery of mercury from acid waste residues  

DOEpatents

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.

Greenhalgh, W.O.

1987-02-27

257

What You Need to Know about Mercury  

MedlinePLUS

When you think of mercury, you probably think of the red or silver liquid inside of a thermometer. When you put the thermometer in your mouth, the mercury tells you how high your temperature is. Mercury ...

258

Recovery of mercury from acid waste residues  

DOEpatents

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.

Greenhalgh, Wilbur O. (Richland, WA)

1989-01-01

259

A View of Mercury From Afar  

NASA Website

This image of Mercury, acquired by the Mercury Dual Imaging System (MDIS) aboard NASA's MESSENGER mission on April 23, 2013, allows us to take a step back to view the planet. Prior to the MESSENGER mission, Mercury's surface was often ...

260

Hydride formation on titanium surfaces by cathodic polarization  

NASA Astrophysics Data System (ADS)

The formation of external layers of TiH 2 on titanium metal by cathodic polarization was studied in buffers of oxalic, tartaric and of acetic acids. Reliable and reproducible hydride layers were obtained from pH 0.8 to 5.3. Variations in pH in this region had little influence. The thickness of the hydride layers increased with increasing current density in the range investigated from 0.14 to 6 mA cm -2. Air-formed titanium oxide film inhibited hydride formation for a period, which could last some hours at low current density. Thereafter the hydride layer thickness increased nearly proportionally with time, a typical value after 20 h treatment with 1 mA cm -2 being 13 ?m. The roughness of the surface increased and formation of titanium nodules was observed after treatment with high current density. The current efficiency for hydride formation was approximately 1% at the lowest current densities and 0.15% at 6 mA cm -2. Tafel slopes in the range 0.3-0.4 V/decade indicated an exceptional electrochemical kinetics.

Videm, Ketil; Lamolle, Sébastien; Monjo, Marta; Ellingsen, Jan Eirik; Lyngstadaas, S. Petter; Haugen, Håvard J.

2008-12-01

261

Mercury spills require special cleanup methods, protection  

Microsoft Academic Search

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

Ceaser

1996-01-01

262

Design and analysis of heat exchangers for high pressure metal hydride hydrogen storage  

Microsoft Academic Search

This study explores the development of a hydrogen storage system using high-pressure metal hydride, Ti1.1CrMn. When absorbing hydrogen (filling), the metal hydride releases large amounts of heat causing the hydride temperature to rise. The reaction rate depends on the metal hydride temperature, decreasing significantly if the heat is not removed quickly. To store 5 kg hydrogen needed to drive 300

Milan K Visaria

2011-01-01

263

Hydrogen absorption in CeNiAl: Formation of crystalline and amorphous hydride phases  

Microsoft Academic Search

Hydriding studies on mixed valent intermetallic compound, CeNiAl, have been carried out. Absorption as well as desorption routes have been employed to find the composition range of various hydride phases. Stable hydride composition, CeNiAlHx, with a maximum value of x=3.2, is obtained. No single phase crystalline hydride could be stabilized for x<1.9. Further, it is found that any attempt to

K. Shashikala; A. Sathyamoorthy; P. Raj; W. B. Yelon; S. K. Malik

2007-01-01

264

Field experience with mercury monitors  

SciTech Connect

With US mercury regulations pending and control technologies in the full-scale demonstration stage, accurate and reliable measurement of mercury in flue gas is becoming more important than ever. This article compares the results of field measurements of commercially available mercury monitors to approved reference methods. A key but not-so-surprising finding: not all mercury monitors are created equal. Four commercial continuous and semi-continuous mercury CEMs and three sorbent trap (ST) systems were compared at Allegheny Energy's coal-fired Armstrong Power Station. The results were compared to the US and EU standard EN-13211 reference methods. All the monitors and traps tested performed very well and all the methods were close in terms of precision, but somewhat higher precision was obtained on low-mercury coal. 10 figs., 4 tabs.

Sarunac, N.; Cipriano, D.; Ryan, J.; Schakenbach, J. [Lehigh University Energy Research Center (United States)

2007-08-15

265

Volatilization of Mercury By Bacteria  

PubMed Central

Volatilization of mercury has been observed from various biological media (tissue homogenates, infusion broth, plasma, urine) containing mercuric chloride. That micro-organisms were responsible was indicated by the finding that the rates of volatilization were highly variable, that a latent period often preceded volatilization, that toluene inhibited the process, and that the capacity to volatilize mercury could be transferred from one biological medium to another. Two species of bacteria when isolated and cultured from these homogenates were able to volatilize mercury. Two other bacteria, one of which was isolated from the local water supply, were also highly active. The volatile mercury was identified as mercury vapour. The importance of these findings in relation to the storage of urine samples prior to mercury analysis is discussed.

Magos, L.; Tuffery, A. A.; Clarkson, T. W.

1964-01-01

266

Remediation of mercury contaminated sites - A review.  

PubMed

Environmental contamination caused by mercury is a serious problem worldwide. Coal combustion, mercury and gold mining activities and industrial activities have led to an increase in the mercury concentration in soil. The objective of this paper is to present an up-to-date understanding of the available techniques for the remediation of soil contaminated with mercury through considering: mercury contamination in soil, mercury speciation in soil; mercury toxicity to humans, plants and microorganisms, and remediation options. This paper describes the commonly employed and emerging techniques for mercury remediation, namely: stabilization/solidification (S/S), immobilization, vitrification, thermal desorption, nanotechnology, soil washing, electro-remediation, phytostabilization, phytoextraction and phytovolatilization. PMID:22579459

Wang, Jianxu; Feng, Xinbin; Anderson, Christopher W N; Xing, Ying; Shang, Lihai

2012-04-21

267

[Mercury (and...) through the centuries].  

PubMed

Mercury has a long history, fascinating in its many aspects. Through the centuries--from ancient times to the present day--the metal in its various forms, also known under the name "quicksilver", accompanied the man and was used for diversified purposes. Today, mercury is employed in manufacturing thermometers, barometers, vacuum pumps and explosives. It is also used in silver and gold mining processes. Mercury compounds play a significant role in dentistry, pharmaceutical industry and crop protection. The contemporary use of mercury markedly decreases, but historically speaking, the archives abound in materials that document facts and events occurring over generations and the immense intellectual effort aiming at discovering the true properties and mechanisms of mercury activity. Mercury toxicity, manifested in destruction of biological membranes and binding of the element with proteins, what disturbs biochemical processes occurring in the body, was discovered only after many centuries of the metal exerting its effect on the lives of individuals and communities. For centuries, mercury was present in the work of alchemists, who searched for the universal essence or quintessence and the so-called philosopher's stone. In the early modern era, between the 16th and 19th centuries, mercury was used to manufacture mirrors. Mercury compounds were employed as a medication against syphilis, which plagued mankind for more than four hundred years--from the Middle Ages till mid 20th century, when the discovery of penicillin became the turning point. This extremely toxic therapy resulted in much suffering, individual tragedies, chronic poisonings leading to fatalities and dramatic sudden deaths. In the last fifty years, there even occurred attempts of mentally imbalanced individuals at injecting themselves with metallic mercury, also as a performance-enhancing drug. Instances of mass mercury poisoning occurred many times in the past in consequence of eating food products poisoned with organic mercury compounds originating from the natural environment. PMID:21863739

K?ys, Ma?gorzata

268

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

Microsoft Academic Search

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.

Zhou Long; Chen Chen; Xiandeng Hou; Chengbin Zheng

2012-01-01

269

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

Microsoft Academic Search

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.

Zhou Long; Chen Chen; Xiandeng Hou; Chengbin Zheng

2012-01-01

270

Heat\\/mass flow enhancement design for a metal hydride assembly. Phase II. Final report  

Microsoft Academic Search

The development and demonstration of a metal hydride\\/chemical heat pump (MHHP) is reported. In the design of the MHHP, heat transfer was considered to be the key technical study area. Therefore, the goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger\\/containment assembly. Phase II consisted of the experimental verification of the hydride

Argabright

1983-01-01

271

Heat\\/mass flow enhancement design for a metal hydride assembly, phase 2  

Microsoft Academic Search

The development and demonstration of a metal hydride\\/chemical heat pump (MHHP) is reported. In the design of the MHHP, heat transfer was considered to be the key technical study area. Therefore, the goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger\\/containment assembly. Phase II consisted of the experimental verification of the hydride

T. A. Argabright

1983-01-01

272

Electron-optical study of $beta$-hydride and hydrogen embrittlement of vanadium  

Microsoft Academic Search

The structure of BETA -hydride precipitated in the bcc matrix of ; hydrogen chsrged vanadium has been studied by electron diffraction in conjunction ; with electronmicroscopy. The BETA -hydride precipitate particles are cohcrent ; with the matrix, being composed of microscopic domains. Each domain is an ; elementary hydride of the monoclinic structure with the axial ratio of about 1.10

S. Takano; T. Suzuki

1974-01-01

273

Measurements of metal hydride hydrogen tank for hybrid electrical chair with photovoltaic and fuel cell  

Microsoft Academic Search

This paper discusses the temperature related hydrogen input and output characteristics of a metal hydride tank to be used for a hybrid electrical wheelchair with photovoltaic cells and fuel cells. The temperature of a metal hydride tank increases when it is filled with hydrogen and decreases as the hydrogen is ejected. A metal hydride tank is unable to eject hydrogen

Yoshihiko Takahashi; Yuuta Kaji

2011-01-01

274

A MODEL FOR THE RATIONALIZATION OF SALINE AND METALLIC HYDRIDE FORMATION  

Microsoft Academic Search

The exothermic, reversible formation of solid hydrides from the elements ; is rationalized on the basis of a model in which the hydride consists of hydrogen ; anions and metal cations, the latter likewise engaging in metal--metal bonding in ; the metallic hydrides. The latti ce energy is evaluated as the sum of the ; Madelung energy and this metal--metal

T Gibb; T. R. P. Jr

1962-01-01

275

The coordination chemistry of organo-hydride donors: new prospects for efficient multi-electron reduction.  

PubMed

In biological reduction processes the dihydronicotinamides NAD(P)H often transfer hydride to an unsaturated substrate bound within an enzyme active site. In many cases, metal ions in the active site bind, polarize and thereby activate the substrate to direct attack by hydride from NAD(P)H cofactor. This review looks more widely at the metal coordination chemistry of organic donors of hydride ion--organo-hydrides--such as dihydronicotinamides, other dihydropyridines including Hantzsch's ester and dihydroacridine derivatives, those derived from five-membered heterocycles including the benzimidazolines and benzoxazolines, and all-aliphatic hydride donors such as hexadiene and hexadienyl anion derivatives. The hydride donor properties--hydricities--of organo-hydrides and how these are affected by metal ions are discussed. The coordination chemistry of organo-hydrides is critically surveyed and the use of metal-organo-hydride systems in electrochemically-, photochemically- and chemically-driven reductions of unsaturated organic and inorganic (e.g. carbon dioxide) substrates is highlighted. The sustainable electrocatalytic, photochemical or chemical regeneration of organo-hydrides such as NAD(P)H, including for driving enzyme-catalysed reactions, is summarised and opportunities for development are indicated. Finally, new prospects are identified for metal-organo-hydride systems as catalysts for organic transformations involving 'hydride-borrowing' and for sustainable multi-electron reductions of unsaturated organic and inorganic substrates directly driven by electricity or light or by renewable reductants such as formate/formic acid. PMID:23507957

McSkimming, Alex; Colbran, Stephen B

2013-06-21

276

Hydrogen storage systems based on hydride materials with enhanced thermal conductivity  

Microsoft Academic Search

The reaction of hydrogen gas with a metal to form a metal hydride is exothermic. If the heat released is not removed from the system, the resulting temperature rise of the hydride will reduce the hydrogen absorption rate. Hence, hydrogen storage systems based on hydride materials must include a way to remove the heat generated during the absorption process. The

Hui Wang; Ajay K. Prasad; Suresh G. Advani

277

Catalytic activity of cerium and neodymium hydrides in the hydrogenation of ethylene  

Microsoft Academic Search

1.The hydrides of Ce and Nd are catalytically active in the hydrogenation of ethylene; the activity of the hydrides depends on the conditions of preliminary thermovacuum treatment and the method of conducting the reaction.2.The catalytic activity of the hydrides of Ce and Nd is evidently associated with the presence of superstoichiometric hydrogen in the lattice of the inactive dihydrides.

Yu. S. Khodakov; S. N. Torbin; Kh. M. Minachev

1972-01-01

278

Hydride behavior in Zircaloy cladding tube during high-temperature transients  

Microsoft Academic Search

In order to study the hydride behavior in high burnup fuel cladding during temperature transients expected in anticipated operational occurrences and accidents, unirradiated hydrided Zircaloy-4 cladding tubes were rapidly heated to temperatures ranging from 673 to 1173K and annealed for holding time ranging from 0 to 3600s. Hydrides were localized in the peripheral region of the cladding tubes prior to

Fumihisa Nagase

2011-01-01

279

Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications  

Microsoft Academic Search

Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125 µm in order to compare it with a

M. M. Barreiro; D. R. Grana; G. A. Kokubu; M. I. Luppo; S. Mintzer; G. Vigna

2010-01-01

280

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

PubMed Central

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.

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

2013-01-01

281

Toxicity of mercury and mercury compounds. (Latest citations from Pollution Abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. The citations examine mercury halides, organic mercury compounds, mercury metal, and mercury vapor. Metabolism, toxicology, occupational exposure, symptoms of exposure, mechanisms of interaction with biological systems, demographics of mercury accumulation and poisoning, and case reports are considered. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1993-02-01

282

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

Microsoft Academic Search

.   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

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

1998-01-01

283

Heat-actuated metal hydride hydrogen compressor testing  

SciTech Connect

Electric utilities use hydrogen for cooling turbine generators. The majority of the utilities purchase the gas from industrial gas markets. On-site electrolytic hydrogen production may prove advantageous both logistically and economically. In order to demonstrate this concept, Public Service Electric and Gas Co. (PSE and G) and EPRI installed an electrolyzer at the Sewaren (NJ) station. To compress the gas, PSE and G purchased a heat-activated metal hydride compressor from Ergenics, Inc. This report describes closed- and open-cycle tests conducted on this metal hydride hydrogen compressor. Test systems, plans, methodologies, and results are presented. A brief discussion evaluates these performance results, addresses some of the practical problems involved with electrolyzer-compressor interface, and compares the costs and benefits of metal hydride versus mechanical hydrogen compression for utility generator cooling.

Piraino, M.; Metz, P.D.; Nienke, J.L.; Freitelberg, A.S.; Rahaman, R.S.

1985-09-01

284

CO2 hydrogenation on a metal hydride surface.  

PubMed

The catalytic hydrogenation of CO(2) at the surface of a metal hydride and the corresponding surface segregation were investigated. The surface processes on Mg(2)NiH(4) were analyzed by in situ X-ray photoelectron spectroscopy (XPS) combined with thermal desorption spectroscopy (TDS) and mass spectrometry (MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). CO(2) hydrogenation on the hydride surface during hydrogen desorption was analyzed by catalytic activity measurement with a flow reactor, a gas chromatograph (GC) and MS. We conclude that for the CO(2) methanation reaction, the dissociation of H(2) molecules at the surface is not the rate controlling step but the dissociative adsorption of CO(2) molecules on the hydride surface. PMID:22433948

Kato, Shunsuke; Borgschulte, Andreas; Ferri, Davide; Bielmann, Michael; Crivello, Jean-Claude; Wiedenmann, Daniel; Parlinska-Wojtan, Magdalena; Rossbach, Peggy; Lu, Ye; Remhof, Arndt; Züttel, Andreas

2012-03-20

285

H2 fuel prototype hydride bed performance tests  

SciTech Connect

H2Fuel is a project to design, build, and demonstrate a hydrogen-electric hybrid city bus for Augusta, GA. The H2Fuel bus uses metal hydride technology for on-board hydrogen fuel storage. This document reports on tests by the Savannah River Technology Center (SRTC) to measure the performance of the H2Fuel prototype hydride bed. Bed diameter measurements were made before and after hydrogen testing. Seven hydrogen absorption-desorption cycles were completed. Significant results include: - maximum hydrogen capacity of approximately 3500 STP liters (0.315 kg) - practical hydrogen capacity of approximately 3000 STP liters (0.270 kg) - absorption tests at four hydrogen supply pressures (75, 100, 140, and 300 psia) - desorption tests at three hydrogen rates (20, 30, and 50 slpm) - no measurable swelling of the hydride bed

Dyer, E.F.

1996-10-01

286

Mercury, Vaccines, and Autism  

PubMed Central

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.

Baker, Jeffrey P.

2008-01-01

287

Cadmium and mercury nephrotoxicity.  

PubMed

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 groundwater. Animals (including man and domestic varieties) can accumulate harmful concentrations of toxic metals. 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, individuals 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. PMID:6877384

Nicholson, J K; Kendall, M D; Osborn, D

288

Method for scavenging mercury  

SciTech Connect

Disclosed herein is a method for removing mercury from a gas stream comprising contacting the gas stream with a getter composition comprising bromine, bromochloride, sulphur bromide, sulphur dichloride or sulphur monochloride and mixtures thereof. In one preferred embodiment the getter composition is adsorbed onto a sorbent. The sorbent may be selected from the group consisting of flyash, limestone, lime, calcium sulphate, calcium sulfite, activated carbon, charcoal, silicate, alumina and mixtures thereof. Preferred is flyash, activated carbon and silica.

Chang, Shih-Ger (El Cerrito, CA); Liu, Shou-Heng (Kaohsiung, TW); Liu, Zhao-Rong (Beijing, CN); Yan, Naiqiang (Berkeley, CA)

2011-08-30

289

Apparatus for mercury refinement  

DOEpatents

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.

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

1991-07-16

290

Method for mercury refinement  

DOEpatents

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.

Grossman, Mark W. (Belmont, MA); Speer, Richard (Reading, MA); George, William A. (Rockport, MA)

1991-01-01

291

Apparatus for mercury refinement  

DOEpatents

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.

Grossman, Mark W. (Belmont, MA); Speer, Richard (Reading, MA); George, William A. (Rockport, MA)

1991-01-01

292

Method for mercury refinement  

DOEpatents

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.

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

1991-04-09

293

Messsenger: Return To Mercury  

NASA Astrophysics Data System (ADS)

MESSENGER (Mercury Surface, Space ENvironment, GEochemistry, and Ranging) is a competitively-selected NASA Discovery mission to reach Mercury and orbit that planet for one Earth year, gathering data with a miniaturized scientific payload. The spacecraft will fly by Mercury in 2007 and 2008 prior to entering Mercury orbit in April 2009. The status of the mission, spacecraft, and payload at the time of the May 2001 Preliminary Design Review are documented in Solomon et al. (2001), Gold et al. (2001), and Santo et al. (2001). Following confimation for development by NASA in June 2001, the mission design, spacecraft, and payload have continued to mature. The thermal environment, instrument co-alignment requirements, propellant requirements, and mass budget dictated by launch vehicle constraints have led to the implementa- tion of a number of innovations in the thermal design of both the payload instru- mentation and the spacecraft itself. The design for the gamma-ray spectrometer has been shifted from a scintillator detector to a cooled-germanium detector to increase the expected signal to noise ratio, and the neutron spectrometer detector has been en- larged as well. Detailed planning for an integrated data-collection strategy combines the required measurements for mission success with downlink and onboard recorder management. Work on the telecommunications subsystem during spacecraft develop- ment has also led to higher expected data rates. Following the Critical Design Review in March 2002, MESSENGER enters the fabrication phase. Flight instruments will be delivered in early 2003 as integration and test begin. The project remains on schedule and on budget for launch in March 2004.

McNutt, Ralph L., Jr.; Solomon, Sean C.; Gold, Robert E.; Santo, Andrew G.; MESSENGER Team

294

Method for preparing hydride configurations and reactive metal surfaces  

DOEpatents

A method for preparing reactive metal surfaces, particularly uranium surfaces is disclosed, whereby the metal is immediately reactive to hydrogen gas at room temperature and low pressure. The metal surfaces are first pretreated by exposure to an acid which forms an adherent hydride-bearing composition on the metal surface. Subsequent heating of the pretreated metal at a temperature sufficient to decompose the hydride coating in vacuum or inert gas renders the metal surface instantaneously reactive to hydrogen gas at room temperature and low pressure.

Silver, G.L.

1984-05-18

295

METHOD OF PREPARING SINTERED ZIRCONIUM METAL FROM ITS HYDRIDES  

DOEpatents

The invention relates to the preparation of metal shapes from zirconium hydride by powder metallurgical techniques. The zirconium hydride powder which is to be used for this purpose can be prepared by rendering massive pieces of crystal bar zirconium friable by heat treatment in purified hydrogen. This any then be ground into powder and powder can be handled in the air without danger of it igniting. It may then be compacted in the normal manner by being piaced in a die. The compact is sintered under vacuum conditions preferably at a temperature ranging from 1200 to 1300 deg C and for periods of one to three hours.

Angier, R.P.

1958-02-11

296

Metal hydride reasearch and development program at Brookhaven National Laboratory  

SciTech Connect

A progress report is presented covering work performed in the hydrogen materials development program at Brookhaven National Laboratory (BNL) for FY78 which encompasses the time period from October 1, 1977 through September 30, 1978. The subjects to be discussed here concern properties of importance in the utilization of metal hydrides as energy storage media. Most of the areas of research were initiated prior to FY78, however all of the results contained in this manuscript were obtained during the aforementioned period of time. The following subjects will be discussed: the properties of ferro-titanium and chrome-titanium alloy hydrides.

Johnson, J.R.; Reilly, J.J.

1978-01-01

297

Electrical Resistivities of Nonstoichiometric Cerium Hydride Single Crystals  

Microsoft Academic Search

Electrical resistivities as a function of temperature (?130° to 25°C) were determined on single crystals of cerium hydride ranging in composition from CeH1.94&sngbnd;CeH2.85. Measurements were performed in an inert-atmosphere dry box using the four-point probe technique. Cerium hydride exhibited metallic behavior in the range CeH1.9&sngbnd;CeH2.7. However, at a composition of about CeH2.85, a positive temperature coefficient of conductivity indicative of

G. G. Libowitz; J. G. Pack

1969-01-01

298

OBSERVATION AND MECHANISM OF HYDRIDE IN ZIRCALOY-4 AND LOCAL HYDRIDE RE-ORIENTATION INDUCED BY HIGH PRESSURE AT HIGH TEMPERATURES  

SciTech Connect

Hydrided Zircaloy-4 samples were produced by a gas charging method to desired amounts of hydrogen. For low hydrogen content samples, the hydrided platelets appear elongated and needle-like, orientated in the circumferential direction. Mechanical testing was carried out by the ring compression method at various temperatures. Samples with higher hydrogen concentration resulted in lower strain before fracture and reduced maximum load. The trend between temperature and ductility was also very clear: increasing temperatures resulted in increased ductility of the hydrided cladding. A single through-wall crack was observed for a hydrided sample having very high hydrogen concentration under ring compression testing. For samples having lower hydrogen concentrations, the fracture surfaces traversed both circumferential and radial directions, and for which voids were observed near the hydrides. Mechanical tests to study hydride reorientation in these samples are under way, and the results will be reported in the near future.

Yan, Yong [ORNL; Blackwell, Andrew S [ORNL; Plummer, Lee K [ORNL; Radhakrishnan, Balasubramaniam [ORNL; Gorti, Sarma B [ORNL; Clarno, Kevin T [ORNL

2013-01-01

299

Fly Ash and Mercury Oxidation\\/Chlorination Reactions  

Microsoft Academic Search

Mercury is a known pollutant that has detrimental effect on human health and environment. The anthropogenic emissions of mercury account for 10 to 30% of worldwide mercury emissions. There is a need to control\\/reduce anthropogenic mercury emissions. Many mercury control technologies are available but their effectiveness is dependent on the chemical form of mercury, because different chemical forms of mercury

Sukh Sidhu; Patanjali Varanasi

2008-01-01

300

Urinary mercury in people living near point sources of mercury emissions  

Microsoft Academic Search

As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an

Lars Barregard; Milena Horvat; Barbara Mazzolai; Gerd Sällsten; Darija Gibicar; Vesna Fajon; Sergio diBona; John Munthe; Ingvar Wängberg; Marie Haeger Eugensson

2006-01-01

301

Uranium Hydride Nucleation Kinetics: Effects of Oxide Thickness and Vacuum Outgassing  

SciTech Connect

Many factors such as impurities in the oxide and metal, microstructure, gas impurities, and oxide thickness may influence the rate and location of the nucleation of hydride on uranium. This work has concentrated on isolating one of these variables, the oxide thickness, and measuring the effect of the oxide thickness on uranium hydride nucleation. Uranium samples, all from the same lot, were prepared with different oxide thicknesses. The oxide thickness was measured using Rutherford Backscattering Spectroscopy. Oxidized uranium samples were then exposed to ultra-high purity hydrogen gas under constant volume conditions. Decreases in pressure indicated hydrogen uptake by the sample. The time for hydride nucleation--as well as the maximum hydriding rate--was then calculated from the measured decreases in pressure. The time to nucleate a hydride was found to increase whereas the maximum hydriding rate was found to decrease with increasing oxide thickness. The density of hydride pits also decreased with increasing oxide thickness. The observed results support the argument that the nucleation of hydride is controlled somewhat by diffusion of hydrogen through the oxide layer. Vacuum outgassing of samples, thereby removing the oxide impurities and keeping the oxide thickness constant, dramatically decreased the nucleation time and increased the maximum hydriding rate. Again, this is consistent with hydrogen diffusion through the oxide controlling the nucleation of hydride. Impurities in the oxide layer can decrease the diffusivity of hydrogen and therefore delay the nucleation of uranium hydride.

David F. Teter; Robert J. Hanrahan; Christopher J. Wetteland

2001-03-01

302

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

303

Near Global Mosaic of Mercury  

Microsoft Academic Search

In 2008 the MESSENGER spacecraft made two close flybys (M1 and M2) of Mercury and imaged about 74% of the planet at a resolution of 1 km per pixel, and at higher resolution for smaller portions of the planet. The Mariner 10 spacecraft imaged about 42% of Mercury's surface more than 30 years ago. Combining image data collected by the

K. J. Becker; M. S. Robinson; T. L. Becker; L. A. Weller; S. Turner; L. Nguyen; C. Selby; B. W. Denevi; S. L. Murchie; R. L. McNutt; S. C. Solomon

2009-01-01

304

The Clean Air Mercury Rule  

SciTech Connect

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.

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

2005-07-01

305

Exploring Mercury. The iron planet  

Microsoft Academic Search

How did Mercury get such an enormous iron core? Why is its tectonic framework so different from any other planet or satellite? What is its crystal composition? Why is the crust so depleted in iron when the interior is so rich in that element? What are the polar deposits? Where do the elements in the exosphere come from? Mercury is

Robert G. Strom; Ann L. Sprague

2003-01-01

306

Ion trajectories in Mercury's magnetosphere  

Microsoft Academic Search

The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere

M. Sarantos; P. Reiff; R. Killen

2003-01-01

307

Experiments with Mercury Jet Interrupters  

Microsoft Academic Search

The Paper describes an experimental attempt to ascertain the form of the mercury column issuing from a hole in the side of a rotating drum, that is continuously supplied with mercury by centrifugal action.Incidentally a new form of interrupter is introduced, in which the interior is visible through a window in the lid. The arrangement forms a suitable apparatus for

C E S Phillips

1915-01-01

308

Comparison of irradiation hardening and microstructure evolution in ion-irradiated delta and epsilon hydrides  

NASA Astrophysics Data System (ADS)

A ?-Zr-hydride was irradiated with 6.4 MeV Fe3+ ions to clarify the relationship between hardening and microstructural changes of bulk Zr-hydrides under neutron irradiation. Irradiation hardening was measured by nanoindentation tests. Transmission electron microscope cross-sectional observations showed that the deformation mechanism of the ?-Zr-hydride was both slip and twinning. Dislocation loops were observed in the irradiated hydride matrix. These irradiation-induced defects make slip deformation difficult and consequently promote the twin deformation of ?-Zr-hydride. This work is a continuation of the previous our work (J. Nucl. Mater. 419 (2011) 366-370) focused upon ?-Zr-hydride and we discuss a comparison between the two Zr-hydrides.

Oono, Naoko; Kasada, Ryuta; Higuchi, Toru; Sakamoto, Kan; Nakatsuka, Masafumi; Hasegawa, Akiko; Kondo, Sosuke; Iwata, Noriyuki Y.; Matsui, Hideki; Kimura, Akihiko

2013-11-01

309

Hydride vapor phase epitaxy of aluminum nitride  

NASA Astrophysics Data System (ADS)

AlN is a promising substrate material for AlGaN-based UV optoelectronic devices and high-power, high-frequency electronic devices. Since large-area bulk AlN crystals are not readily available, one approach to prepare AlN substrates is to heteroepitaxially deposit thick (e.g., 10-300+ mum) AlN layers by hydride vapor phase epitaxy. Initial efforts focused on growing AlN layers on sapphire substrates with growth rates up to 75 mum/hr. The resulting layers were colorless, smooth, and specular. Subsurface cracking, attributed to the plastic relief of tensile strain from island coalescence, was observed but did not adversely affect the surface morphology of the AlN layers. The surfaces possessed rms roughnesses as low as 0.316 nm over 5 x 5 mum2 sampling areas, but hexagonal hillock formation was observed for thick films grown at high growth rates. TEM revealed that the threading dislocation (TD) density of the films was 2 x 109 cm-2. The high TD densities for direct growth of AlN films on foreign substrates motivated the development of lateral epitaxial overgrowth approaches for defect reduction. Growth of AlN layers on patterned SiC substrates produced coalesced AlN films possessing TD densities below 8.3 x 106 cm -2 in the laterally grown wing regions, as compared to 1.8 x 109 cm-2 in the seed regions. These films, however, cracked on cooldown due to the difference in thermal expansion coefficients for AlN and SiC. To avoid this cracking, AlN layers were grown on patterned sapphire substrates. Although the films were able to be coalesced and contained few or no cracks, the TDs in these films were not confined to the seed regions. This produced a relatively uniform distribution of TDs over the surfaces of the films, with only a modest reduction in the TD density of 1 x 10 8 cm-2. Selective area growth of AlN was also pursued using Si3N4, SiO2, and Ti masks. Growth selectivity and film coalescence was observed for films grown on each masking material, but none of the masks resulted in films with both smooth surface morphologies and low TD densities.

Kamber, Derrick Shane

310

Socioeconomic Consequences of Mercury Use and Pollution  

Microsoft Academic Search

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

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

311

Dental amalgam mercury exposure in rats  

Microsoft Academic Search

The aim of this study was to measure the distribution of mercury, in tissues of rats exposed to amalgam over a two months period. Possible interaction of mercury with copper and zinc in organs was also evaluated. Rats were either exposed to mercury from 4 dental amalgams, or fed the diet containing powdered amalgam during two months. Mercury was measured

Nada Galic; Goranka Prpic-Mehi?ic; Ljerka Prester; Maja Blanuša; Žarka Krnic; Željko Feren?ic

1999-01-01

312

THE CHEMICAL CYCLE AND BIOACCUMULATION OF MERCURY  

Microsoft Academic Search

Because it is very toxic and accumulates in organisms, particularly in fish, mercury is an important pollutant and one of the most studied. Nonetheless we still have an incomplete understanding of the factors that control the bioconcentration of mercury. Elemental mercury is efficiently transported as a gas around the globe, and even remote areas show evidence of mercury pollution originating

Francois M. M. Morel; Anne M. L. Kraepiel; Marc Amyot

1998-01-01

313

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.

314

Methods for dispensing mercury into devices  

DOEpatents

A process for dispensing mercury into devices which requires mercury. Mercury is first electrolytically separated from either HgO or Hg.sub.2 Cl.sub.2 and plated onto a cathode wire. The cathode wire is then placed into a device requiring mercury.

Grossman, Mark W. (Belmont, MA); George, William A. (Rockport, MA)

1987-04-28

315

The chemistry of atmospheric mercury: a review  

Microsoft Academic Search

The atmosphere is an important transient reservoir of mercury. In addition to its great capacity, the chemical processes transforming mercury between the elemental and divalent states strongly influence the transport characteristics and deposition rate of this toxic metal back to the ground. Modeling efforts to assess global cycling of mercury require an in-depth knowledge of atmospheric mercury chemistry. This review

Che-Jen Lin; Simo O. Pehkonen

1999-01-01

316

Methods for dispensing mercury into devices  

DOEpatents

A process is described for dispensing mercury into devices which requires mercury. Mercury is first electrolytically separated from either HgO or Hg[sub 2]Cl[sub 2] and plated onto a cathode wire. The cathode wire is then placed into a device requiring mercury. 2 figs.

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

1987-04-28

317

Catalytic arene hydrogenation using early transition metal hydride compounds  

SciTech Connect

Progress was achieved in four areas: development of surface supported Group 5 metal organometallic compounds for catalytic arene hydrogenation, isolation and reactivity of possible intermediates in catalytic arene hydrogenation, synthesis and characterization of new d[sup 0]-metal hydride compounds, and stoichiometric reactivity of d[sup 0] metal hydrido, aryloxide compounds. (DLC)

Rothwell, I.P.

1993-03-15

318

Free-Radical Addition of Trimethyltin Hydride to Allenes.  

National Technical Information Service (NTIS)

The azobisisobutyronitrile-catalyzed addition of trimethyltin hydride to allene, 1,2-butadiene, 2,3-pentadiene, 2-methyl-2,3-pentadiene, and 3-methyl-1,2-butadiene was studied. Structures and configurations of all of the adducts were assigned on the basis...

H. G. Kuivila W. Rahman R. H. Fish

1965-01-01

319

Electrochromism of Mg-Ni hydride switchable mirrors  

NASA Astrophysics Data System (ADS)

Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 less than z less than 3.7 shows that addition of one Mg atom per Mg2Ni gives the best ab/desorption kinetics for hydrogen. X- ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure- composition isotherm of Mg2NiHx is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg2NiH4. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.

Isidorsson, Jan; Giebels, I. A.; Di Vece, M.; Griessen, Ronald

2001-11-01

320

Electronic-Energy-Band Structure of Uranium Hydride.  

National Technical Information Service (NTIS)

We have calculated the electronic energy bands of alpha and beta UH sub 3 . These systems are unique among hydride formers in that a transformation directly to a trihydride occurs without an intervening dihydride phase and in that two trihydride structure...

A. C. Switendick

1982-01-01

321

Search for proton magnetic resonance in ferromagnetic ?-uranium hydride  

Microsoft Academic Search

Proton magnetic resonance (PMR) in a ferromagnetic?-uranium hydride at 77 K has been searched unsuccessfully between 4 and 420 MHz. The present communication reports this experiment and its objectives, and justifies the swept frequency range on the basis of PMR data obtained in the paramagnetic phase and of a new analysis of the Flotow and Osborne low temperature specific heat

J. C. Fernandes; J. B. De Oliveira e Souza

1985-01-01

322

Experimental studies on the behaviours of hydride heat storage system  

Microsoft Academic Search

Experimental examinations and a lumped system model are used to describe the heat transfer characteristics in the design of a single tube type metal hydride heat storage vessel. The apparatus studied was fed heat by water vaporized by an electric furnance with a 3 kWh x 2 capacity. An annular tube in the middle of the reactor vessel contained the

M. Kawamura; S. Ono; S. Higano

1982-01-01

323

Effect of CO in Reformed Gas on Fluorinated Metal Hydride  

NASA Astrophysics Data System (ADS)

For the purpose of following electricity demand change and improving the efficiency of generation for fuel cells, a new system, which is called metal hydride intermediate buffer method, is developing. The system uses the selective reacting function of hydrogen on metal hydride materials. It is said that metal hydride could be easy to be poisoned by impurities except for hydrogen. Therefore a surface treatment has been adopted with the material to avoid it. We have found that the treatment is effective against H2O and CO2, which exist mainly in the reformed gas. One of general concerns about poisoning by CO included slightly in the reformed gas must be confirmed. In order to verify the treatment effect against CO, hydrogen absorption and desorption experiment were repeated with the simulated reformed gas (SRG) including 100ppm or 1% of CO concentration. In the result, it has been clarified that the metal hydride keeps the absorption property in spite of CO existence. In the CO 100ppm condition, functional deterioration due to CO-poisoning is not recognized at all. The hydrogen absorption rate is significantly reduced in the CO 1% experiment compared with the fuel gas without CO, but the absorption property has not been lost entirely. On the other hand, it has been found that the absorption property is gradually degraded, even if pure hydrogen without any impurities is used.

Sasaki, Ryoichi; Ishida, Masayoshi

324

Investigation of Galvanically Induced Hydriding of Titanium in Saline Solutions.  

National Technical Information Service (NTIS)

Galvanically induced hydriding of commercially pure titanium and titanium-2 nickel alloy was determined in 3.4 wt percent NaCl air-sparged and argon-sparged solutions at 140, 265, and 390F. Hydrogen charging of the titanium via couple assemblies of titani...

L. A. Charlot

1970-01-01

325

Composition and Structure of Sputter Deposited Erbium Hydride Thin Films.  

National Technical Information Service (NTIS)

Erbium hydride thin films are grown onto polished, a-axis (alpha) A1 (sub 2)O(sub 3) (sapphire) substrates by reactive ion beam sputtering and analyzed to determine composition, phase and microstructure. Erbium is sputtered while maintaining a H(sub 2) pa...

D. P. Adams J. A. Romero M. A. Rodriguez J. A. Floro J. C. Banks

2000-01-01

326

Towards an Accurate Wave Function for Positronium Hydride  

Microsoft Academic Search

A variational wave function for the ground state of positronium hydride is presented. The wave function is considerably more accurate than any previously reported. The only simplifications used are (a) only kinetic and Coulombic potential energy terms are included in the Hamiltonian, (b) the motion of the proton is ignored, and (c) the nucleus-positron distance is excluded from the wave

C. F. Lebeda; David M. Schrader

1969-01-01

327

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

Microsoft Academic Search

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

2001-01-01

328

Electronic Principles of Some Trends in Properties of Metallic Hydrides  

NASA Astrophysics Data System (ADS)

Due to their extensive present, important and versatile potential applications, metal hydrides (MH) are among the most investigated solid-state systems. Theoretical, numerical and experimental studies have provided a considerable knowledge about their structure and properties, but in spite of that, the basic electronic principles of various interactions present in MH have not yet been completely resolved. Even in the simplest MH, i.e. alkali hydrides (Alk-H), some trends in physical properties, and especially their deviations, are not well understood. Similar doubts exist for the alkaline-earth hydride (AlkE-H) series, and are even more pronounced for complex systems, like transition metal-doped AlkE-H, alanates and borohydrides. This work is an attempt of explaining some trends in the physical properties of Alk-H and AlkE-H, employing the Bader analysis of the charge distribution topology evaluated by first-principle all-electron calculations. These results are related to some variables commonly used in the explanation of experimental and calculated results, and are also accompanied by simple tight-binding estimations. Such an approach provides a valuable insight in the characteristics of M-H and H-H interactions in these hydrides, and their possible changes along with external parameters, like temperature, pressure, defect or impurity introduction. The knowledge of these basic interactions and processes taking place in simple MH are essential for the design and optimisation of complex MH-systems interesting for practical hydrogen storage applications.

Ivanovi?, Nenad; Novakovi?, Nikola; Colognesi, Daniele; Radisavljevi?, Ivana; Ostoji?, Stanko

329

Intermetallic hydrides: A review with ab initio aspects  

Microsoft Academic Search

The review aims to provide a coverage of different classes of intermetallic systems, which have the ability of absorbing hydrogen in different amounts, like binary and ternary Laves phases and Haucke-type intermetallics. Such intermetallic hydrides are attractive for applied research as potential candidates for on-board vehicular use (engines, batteries, etc.). Focus is made here on the fundamental features regarding the

Samir F. Matar

2010-01-01

330

Reactions of Calcium, Magnesium and Cerium Hydrides with Aqueous Solutions.  

National Technical Information Service (NTIS)

The report describes studies of reactions of CaH2, MgH2 and CeH2 with D2O solutions. The purpose of these studies was to establish the fate of hydride hydrogen in such reactions and the stoichiometry of reactions in which metal ions compete with D(+) as o...

R. A. Sutula J. B. Hunt

1965-01-01

331

HYDRIDATION OF CERIUM ALLOYS WITH MAGNESIUM AND ALUMINUM  

Microsoft Academic Search

Hydridation of Ce - Mg- Al alloy at room temperature and normal pressure ; was studied with an alloy containing 70 to 90 wt% Ce. Maximum of hydrogen ; absorption was in the region of 5 to 10% Al and 35 to 80% Mg. An increased ; amount of Al in the Ce-- Mg system contributes to increased hydrogen absorption.

V. I. Mikheeva; Z. K. Sterlyadkina; A. A. CHertkov

1963-01-01

332

Sintering of sponge and hydride-dehydride titanium powders  

Microsoft Academic Search

The sintering behavior of compacts produced from sponge and hydride-dehydride (HDH) Ti powders was examined. Compacts were vacuum sintered at 1200 or 1300 deg C for 30, 60, 120, 240, 480 or 960 minutes. The porosity decreased with sintering time and\\/or temperature in compacts produced from the HDH powders. Compacts produced from these powders could be sintered to essentially full

David E. Alman; Stephen J. Gerdemann

2004-01-01

333

The Origin of Mercury  

NASA Astrophysics Data System (ADS)

Mercury’s unusually high mean density has always been attributed to special circumstances that occurred during the formation of the planet or shortly thereafter, and due to the planet’s close proximity to the Sun. The nature of these special circumstances is still being debated and several scenarios, all proposed more than 20 years ago, have been suggested. In all scenarios, the high mean density is the result of severe fractionation occurring between silicates and iron. It is the origin of this fractionation that is at the centre of the debate: is it due to differences in condensation temperature and/or in material characteristics (e.g. density, strength)? Is it because of mantle evaporation due to the close proximity to the Sun? Or is it due to the blasting off of the mantle during a giant impact? In this paper we investigate, in some detail, the fractionation induced by a giant impact on a proto-Mercury having roughly chondritic elemental abundances. We have extended the previous work on this hypothesis in two significant directions. First, we have considerably increased the resolution of the simulation of the collision itself. Second, we have addressed the fate of the ejecta following the impact by computing the expected reaccretion timescale and comparing it to the removal timescale from gravitational interactions with other planets (essentially Venus) and the Poynting Robertson effect. To compute the latter, we have determined the expected size distribution of the condensates formed during the cooling of the expanding vapor cloud generated by the impact. We find that, even though some ejected material will be reaccreted, the removal of the mantle of proto-Mercury following a giant impact can indeed lead to the required long-term fractionation between silicates and iron and therefore account for the anomalously high mean density of the planet. Detailed coupled dynamical chemical modeling of this formation mechanism should be carried out in such a way as to allow explicit testing of the giant impact hypothesis by forthcoming space missions (e.g. MESSENGER and BepiColombo).

Benz, W.; Anic, A.; Horner, J.; Whitby, J. A.

2007-10-01

334

Transit of Mercury  

NSDL National Science Digital Library

It isn't every day that one gets to view a transit of Mercury. In fact, it's an event that only occurs approximately twelve times a century. For those of you who missed this event on November 8th, the researchers and scientists at the Exploratorium in San Francisco have created this program that contains the complete event and offer it to visitors to this lovely website. The transit was recorded from Kitt Peak in Arizona, and visitors to the site can watch a brief introduction to the program, and then watch various images from the webcast, complete with audio commentary at the beginning of each hour of coverage.

2006-01-01

335

Fluorescent sensor for mercury  

SciTech Connect

The present invention provides a sensor for detecting mercury, comprising: a first polynucleotide, comprising a first region, and a second region, a second polynucleotide, a third polynucleotide, a fluorophore, and a quencher, wherein the third polynucleotide is optionally linked to the second region; the fluorophore is linked to the first polynucleotide and the quencher is linked to the second polynucleotide, or the fluorophore is linked to the second polynucleotide and the quencher is linked to the first polynucleotide; the first region and the second region hybridize to the second polynucleotide; and the second region binds to the third polynucleotide in the presence of Hg.sup.2+ ions.

Wang, Zidong (Urbana, IL); Lee, Jung Heon (Evanston, IL); Lu, Yi (Champaign, IL)

2011-11-22

336

Hydride Compressor Sorption Cooler and Surface Contamination Issues  

NASA Astrophysics Data System (ADS)

A continuous-duty hydrogen sorption cryocooler is being developed for the Planck spacecraft, a mission to map the cosmic microwave background beginning in 2007. This cryocooler uses six individual compressor elements (CEs) filled with the hydriding alloy LaNi4.78Sn0.22 to provide high-pressure (50 bar) hydrogen to a Joule-Thomson (J-T) expander and to absorb low-pressure (~0.3 bar) gas from liquid hydrogen reservoirs cooled to ~18K. Quadrupole Mass Spectrometry (QMS) showed methane in these hydride beds after cycling during initial operation of laboratory tests of the Planck engineering breadboard (EBB) cooler. These contaminants have caused problems involving plugged J-T expanders. The contaminants probably come from reactions with residual hydrocarbon species on surfaces inside the hydride bed. The hydride bed in each CE is contained in an annular volume called a ``gas-gap heat switch,'' which serves as a reversible, intermittent thermal path to the spacecraft radiator. The gas-gap is either ``off'' (i.e., its pressure <1.3 Pa), or ``on'' (i.e., hydrogen gas at ~4 kPa). The hydrogen pressure is varied with an independent hydride actuator containing ZrNiHx. Early EBB cooler tests showed increasing parasitic heat losses from the inner beds, suggesting residual pressures in the gas gap during its ``off'' state. The pressure was shown to be due to hydrogen from outgassing from metallic surfaces in the gas gap and hydrogen permeation through the inner sorbent bed wall. This gas accumulation has serious end-of-life implications, as the ZrNi actuator has limited storage capacity and any excess hydrogen would necessarily affect its operation. This paper summarizes experiments on the behavior of hydrogen in the gas gap switch and formation of methane in the CE sorbent beds.

Bowman, R. C.; Reiter, J. W.; Prina, M.; Kulleck, J. G.; Lanford, W. A.

2003-07-01

337

49 CFR 173.164 - Mercury (metallic and articles containing mercury).  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Mercury (metallic and articles containing mercury). 173.164 Section 173.164 Transportation...Other Than Class 1 and Class 7 § 173.164 Mercury (metallic and articles containing...

2012-10-01

338

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...

339

49 CFR 173.164 - Mercury (metallic and articles containing mercury).  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Mercury (metallic and articles containing mercury). 173.164 Section 173.164 Transportation...Other Than Class 1 and Class 7 § 173.164 Mercury (metallic and articles containing...

2011-10-01

340

Natural selection for resistance to mercury pollution  

Microsoft Academic Search

Summary The survival under conditions of mercury pollution of two natural populations of the marine gastropodCerithium rupestre, derived from mercury-polluted and mercury-free sites, was tested in the laboratory. The results indicate a significantly higher survival rate for animals derived from the mercury-polluted site, in each of six repetitive experiments. We conclude that mercury resistance in marine organisms is reinforced in

R. Baker; B. Lavie; E. Nevo

1985-01-01

341

Toxicological profile for mercury. Update. Final report  

SciTech Connect

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.

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

1994-05-01

342

Elemental mercury exposure in early pregnancy  

SciTech Connect

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.

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

343

Effects of ingesting mercury-containing bacteria on mercury tolerance and growth rates of ciliates  

Microsoft Academic Search

The ciliateUronema nigricans was found to acquire tolerance to mercury after being fed mercury-laden bacteria followed by exposure of washed suspensions of these ciliates to various concentrations of mercury in solution. Significant differences in percent mortality were observed for ciliates fed mercury-laden bacteria compared with control suspensions fed mercury-free bacteria. The phenomenon of acquired mercury tolerance was demonstrated within a

S. G. Berk; A. L. Mills; D. L. Hendricks; R. R. Colwell

1977-01-01

344

Mercury exposures and symptoms in smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China  

Microsoft Academic Search

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?g\\/g creatinine (?g\\/g Cr), 69.3 and 2.32?g\\/g, respectively. The results were significantly higher than that of control group, which is 1.30?g\\/g

Ping Li; Xinbin Feng; Guangle Qiu; Zhonggen Li; Xuewu Fu; Minishi Sakamoto; Xiaojie Liu; Dingyong Wang

2008-01-01

345

Cadmium and mercury nephrotoxicity  

NASA Astrophysics Data System (ADS)

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.

Nicholson, J. K.

1983-08-01

346

Dissociation potential curves of low-lying states in transition metal hydrides. 3. Hydrides of groups 6 and 7.  

PubMed

The dissociation curves of low-lying spin-mixed states in monohydrides of groups 6 and 7 were calculated by using an effective core potential (ECP) approach. This approach is based on the multiconfiguration self-consistent field (MCSCF) method, followed by first-order configuration interaction (FOCI) calculations, in which the method employs an ECP basis set proposed by Stevens and co-workers (SBKJC) augmented by a set of polarization functions. Spin-orbit coupling (SOC) effects are estimated within the one-electron approximation by using effective nuclear charges, since SOC splittings obtained with the full Breit-Pauli Hamitonian are underestimated when ECP basis sets are used. The ground states of group 6 hydrides have Omega = (1)/(2)(X(6)Sigma(+)(1/2)), where Omega is the z component of the total angular momentum quantum number. Although the ground states of group 7 hydrides have Omega = 0(+), their main adiabatic components are different; the ground state in MnH originates from the lowest (7)Sigma(+), while in TcH and ReH the main component of the ground state is the lowest (5)Sigma(+). The present paper reports a comprehensive set of theoretical results including the dissociation energies, equilibrium distances, electronic transition energies, harmonic frequencies, anharmonicities, and rotational constants for several low-lying spin-mixed states in these hydrides. Transition dipole moments were also computed among the spin-mixed states and large peak positions of electronic transitions are suggested theoretically for these hydrides. The periodic trends of physical properties of metal hydrides are discussed, based on the results reported in this and other recent studies. PMID:16480317

Koseki, Shiro; Matsushita, Takeshi; Gordon, Mark S

2006-02-23

347

Evidence of FCC titanium hydride formation in. beta. titanium alloy: An X-ray diffraction study  

SciTech Connect

Three types of titanium hydrides have been reported: delta, epsilon and ..gamma.. hydrides. The delta hydride forms in the composition range from TiH/sub 1.5/ to TiH/sub 1.99/ and has a CaF/sub 2/ structure with metal atoms on an fcc lattice and hydrogen atoms randomly occupying tetrahedral interstitial sites. At higher hydrogen concentrations, TiH/sub 2/, the fct (c/a < 1) epsilon hydride phase is formed below 310 K. The c/a ratio decreases with a decreasing temperature and it reaches and maintains a minimum value of 0.943 below 80 K. The fcc to tetragonal, delta ..-->.. epsilon transformation is apparently diffusionless, similar to that operating in the cubic/tetragonal transformation in zirconium hydride. The metastable fct ..gamma.. hydride having a c/a value of 1.09 or 1.12 forms from solid solutions of hydrogen in the hcp ..cap alpha.. matrix. While the titanium hydride precipitation in ..cap alpha..-Ti and its alloys has attracted extensive investigation, hydride formation in bcc ..beta..-Ti alloys has rarely been studied because they have not been thought to be liable to hydride formation. This paper shows conclusive evidence for the fcc delta hydride phase formation in the ..beta.. phase Ti-30 wt% Mo by x-ray diffraction study.

Shih, D.S.; Birnbaum, H.K.

1986-09-01

348

The Use of Bacteria for Remediation of Mercury Contaminated Groundwater  

EPA Science Inventory

Many processes of mercury transformation in the environment are bacteria mediated. Mercury properties cause some difficulties of remediation of mercury contaminated environment. Despite the significance of the problem of mercury pollution, methods of large scale bioremediation ...

349

76 FR 75446 - Amendment of Class E Airspace; Mercury, NV  

Federal Register 2010, 2011, 2012, 2013

...11-AWP-14] Amendment of Class E Airspace; Mercury, NV AGENCY: Federal Aviation Administration...SUMMARY: This action amends Class E airspace at Mercury, Desert Rock Airport, Mercury, NV. Decommissioning of the Mercury...

2011-12-02

350

MERCURY STABILITY IN THE ENVIRONMENT  

SciTech Connect

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.

John H. Pavlish

1999-07-01

351

Socioeconomic consequences of mercury use and pollution.  

PubMed

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 methylmercury. Humans can also receive toxic doses of mercury through inhalation of elevated concentrations of gaseous elemental mercury. We propose that any effective strategy for reducing mercury exposures requires an examination of the complete life cycle of mercury. This paper examines the life cycle of mercury from a global perspective and then identifies several approaches to measuring the benefits of reducing mercury exposure, policy options for reducing Hg emissions, possible exposure reduction mechanisms, and issues associated with mercury risk assessment and communication for different populations. PMID:17408190

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

2007-02-01

352

MESSENGER Observations of Calcium in Mercury’s Exosphere  

NASA Astrophysics Data System (ADS)

The Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MESSENGER spacecraft has made near-daily observations of calcium in Mercury’s exosphere since orbital observations began in March 2011. UVVS is a scanning grating monochrometer that measures resonantly scattered emission from Ca at 422.7 nm. The data have shown that the principal source of atomic Ca in the exosphere is located in the dawn equatorial sector. Calcium is seen to originate from a small region at high temperature 50,000 K), possibly as a product of the dissociation of calcium-bearing molecules ejected from the surface. Data collected over 8 Mercury years during MESSENGER’s 1-year primary and 1-year first extended missions have indicated that the source strength varies with Mercury’s true anomaly. The Ca flux from the surface is greatest near perihelion and weakest near aphelion, but there is little year-to-year variation in the source strength. The expected calcium source mechanisms, including micrometeoroid impact vaporization, ion sputtering, and dawn vaporization of material deposited on the nightside, do not appear to be consistent with the observations.

Burger, Matthew H.; Killen, R. M.; McClintock, W. E.; Merkel, A. W.; Vervack, R. J.; Sarantos, M.; Cassidy, T. A.

2013-10-01

353

Postoperative Systemic Dissemination of Injected Elemental Mercury  

PubMed Central

There were only a few reports of mercury on pulmonary artery. However, there is no data on surgery related mercury dissemination. The objective of the present article is to describe one case of postoperative injected mercury dissemination. A 19-year-old man presented severe neck pain including meningeal irritation sign and abdominal pain after injection of mercury for the purpose of suicide. Radiologic study showed injected mercury in the neck involving high cervical epidural space and subcutaneous layer of abdomen. Partial hemilaminectomy and open mercury evacuation of spinal canal was performed. For the removal of abdominal subcutaneous mercury, C-arm guided needle aspiration was done. After surgery, radiologic study showed disseminated mercury in the lung, heart, skull base and low spinal canal. Neck pain and abdominal pain were improved after surgery. During 1 month after surgery, there was no symptom of mercury intoxication except increased mercury concentration of urine, blood and hair. We assumed the bone work during surgery might have caused mercury dissemination. Therefore, we recommend minimal invasive surgical technique for removal of injected mercury. If open exposures are needed, cautious surgical technique to prohibit mercury dissemination is necessary and normal barrier should be protected to prevent the migration of mercury.

Kang, Suk-Hyung; Moon, Kyung-Yoon

2011-01-01

354

Mercurial Risks from Acid's Reign.  

ERIC Educational Resources Information Center

|Discussed are the sources, and harmful effects of methylmercury. Research on this problem is reviewed. Suggestions to help anglers reduce their mercury consumption from fish they catch are provided. (CW)|

Raloff, Janet

1991-01-01

355

"Cavitation in a Mercury Target"  

SciTech Connect

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.

West, C.D.

2000-09-06

356

High Power Mercury Switch Study.  

National Technical Information Service (NTIS)

The effort was both a theoretical and experimental program leading to the development of high voltage, high power switching devices which utilize a liquid metal cathode. A series of mercury tubes with plasma injection triggering were built and tested culm...

R. W. Waniek

1967-01-01

357

ULF wave absorption at Mercury  

NASA Astrophysics Data System (ADS)

The field line resonance at Mercury is expected to occur when the ion-ion hybrid (IIH) and/or Alfvén resonance conditions are satisfied. However, the relative efficiency of wave energy absorption at these resonances has not been studied in the context of Mercury's magnetosphere. To understand the efficiency of wave absorption, we evaluate absorption coefficients at the IIH and Alfvén resonances for variable concentrations of sodium and azimuthal and field-aligned wave numbers in 1D multi-ion plasmas. The results show that wave absorption is much more efficient at the IIH resonance than at the Alfvén resonance at Mercury. Our results suggest that the mode conversion efficiency is sensitive to the azimuthal and field aligned wave numbers as well as heavy ion concentration ratio. Therefore, the radial profile of field-line resonances at Mercury can exhibit complex, discontinuous structure.

Kim, Eun-Hwa; Johnson, Jay R.; Lee, Kyung-Dong

2011-08-01

358

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

SciTech Connect

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.

Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

2009-03-10

359

Mercury Toolset for Spatiotemporal Metadata  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

360

Composition and structure of sputter deposited erbium hydride thin films  

SciTech Connect

Erbium hydride thin films are grown onto polished, a-axis {alpha} Al{sub 2}O{sub 3} (sapphire) substrates by reactive ion beam sputtering and analyzed to determine composition, phase and microstructure. Erbium is sputtered while maintaining a H{sub 2} partial pressure of 1.4 x 10{sup {minus}4} Torr. Growth is conducted at several substrate temperatures between 30 and 500 C. Rutherford backscattering spectrometry (RBS) and elastic recoil detection analyses after deposition show that the H/Er areal density ratio is approximately 3:1 for growth temperatures of 30, 150 and 275 C, while for growth above {approximately}430 C, the ratio of hydrogen to metal is closer to 2:1. However, x-ray diffraction shows that all films have a cubic metal sublattice structure corresponding to that of ErH{sub 2}. RBS and Auger electron that sputtered erbium hydride thin films are relatively free of impurities.

ADAMS,DAVID P.; ROMERO,JUAN A.; RODRIGUEZ,MARK A.; FLORO,JERROLD A.; BANKS,JAMES C.

2000-05-10

361

Preparation and X-ray diffraction studies of curium hydrides  

NASA Astrophysics Data System (ADS)

Curium hydrides were prepared by reaction of curium-248 metal with hydrogen and characterized by X-ray powder diffraction. Several of the syntheses resulted in a hexagonal compound with average lattice parameters of a0 = 0.3769(8) nm and c0 = 0.6732(12) nm. These products are considered to be CmH3-? by analogy with the behavior of lanthanide-hydrogen and lighter actinide-hydrogen systems. Face-centered cubic products with an average lattice parameter of a0 = 0.5322(4) nm were obtained from other curium hydride preparations. This parameter is slightly smaller than that reported previously for cubic curium dihydride, CmH2+x (B. M. Bansal and D. Damien, Inorg. Nucl. Chem. Lett., 6, 603, 1970). The present results established a continuation of typical heavy trivalent lanthanide-like behavior of the transuranium actinide-hydrogen systems through curium.

Gibson, J. K.; Haire, R. G.

1985-10-01

362

Low temperature study of structural phase transitions in niobium hydrides  

NASA Astrophysics Data System (ADS)

Niobium (Nb) and its hydrides have been the focus of many studies due to applications as a hydrogen storage material, as a dielectric coating in semiconductor devices and in superconducting radio-frequency cavities. In this paper, we will present the atomic-scale characterization of Nb hydrides using scanning transmission electron microscopy and electron energy loss spectroscopy (EELS) at room and liquid nitrogen temperatures. Although such cavities are formed from ultrahigh purity Nb, using electron beam diffraction, we found that at LN2 temperature, the grains near the surface of cold-worked Nb sheets contain regions exhibiting three different superlattice features, which are identified as ?, ?, and ?-NbHx phases. Z-contrast imaging and EELS at LN2 temperature are utilized to qualify their atomic and electronic structures.

Tao, R.; Romanenko, A.; Cooley, L. D.; Klie, R. F.

2013-07-01

363

Gas-phase Reactions of Hydride Anion, H-  

NASA Astrophysics Data System (ADS)

Rate constants were measured at 300 K for the reactions of the hydride anion, H-, with neutral molecules C2H2, H2O, CH3CN, CH3OH, (CH3)2CO, CH3CHO, N2O, CO2, O2, CO, CH3Cl, (CH3)3CCl, (CH3CH2)2O, C6H6, and D2 using a flowing-afterglow instrument. Experimental work was supplemented by ab initio calculations to provide insight into the viability of reaction pathways. Our reported rate constants should prove useful to models of astrophysical environments where conditions prevail for the existence of both H- and neutral species. The variety of neutral reactants studied includes representative species from prototypical chemical groups, effectively mapping reactivity trends for the hydride anion.

Martinez, Oscar, Jr.; Yang, Zhibo; Demarais, Nicholas J.; Snow, Theodore P.; Bierbaum, Veronica M.

2010-09-01

364

Composition and function in AB{sub 5} hydride electrodes  

SciTech Connect

Multicomponent AB, hydrides are attractive replacements for the cadmium electrode in nickel - cadmium batteries. This paper is concerned with the differential effects of Ni substitution by cobalt, Mn and Al upon electrode corrosion and capacity, using alloys having the generic composition of Al(NiCoMnAl){sub 5} and similar to those used for the preparation of commercial battery electrodes. The corrosion of metal hydride electrodes is determined by two factors, surface passivation due to the presence of surface oxides or hydroxides and crystal lattice expansion - contraction the charge - discharge process. Thus, in addition to determining the effects of Ni substitution we will also address the question of whether an observed change is due to a change lattice expansion or to a change in surface passivation, e.g. the formation a corrosion resistant oxide layer.

Adzic, G.D.; Johnson, J.R.; Mukerjee, S.; McBreen, J.; Reilly, J.J.

1996-12-31

365

Recent geologic activity on Mercury  

NASA Astrophysics Data System (ADS)

Since the MESSENGER spacecraft was inserted into orbit about Mercury in March 2011, global and targeted high-resolution image data sets have been acquired. These images support the conclusion that internal geological activity on Mercury did not end early in planetary history, as had generally been previously thought, but continued to geologically recent times. Three lines of evidence point to recent geological activity on Mercury. (1) There are smooth plains with surface areas up to 1.5×105 km2 that postdate young (morphological class 1) craters, indicating probable Kuiperian-aged volcanism. No volcanic vents, fissures, or flow fronts have been identified on these plains, suggesting that they are products of low-viscosity lavas, consistent with komatiite-like compositions of large areas on Mercury indicated by MESSENGER X-Ray Spectrometer observations. (2) Young lobate scarps transect class 1 craters as large as 30 km in diameter, indicating comparably recent crustal contraction. (3) A number of fresh-appearing, high-reflectance, irregularly shaped and rimless shallow depressions interpreted as pyroclastic vents have few superposed craters, suggesting that they have been recently active. Growing evidence from geological and geochemical observations indicates that Mercury's interior contains a higher abundance of volatile materials than was previously appreciated. Together these findings support the inference that Mercury experienced relatively recent volcanism and tectonic deformation, and the possibility that the planet is geologically active today cannot be discounted.

Xiao, Z.; Strom, R. G.; Blewett, D. T.; Solomon, S. C.; Head, J. W.; Watters, T. R.; Chabot, N. L.; Banks, M. E.; Chapman, C. R.

2011-12-01

366

Hydride precipitation and stresses in zircaloy-4 observed by synchrotron X-ray diffraction  

Microsoft Academic Search

The grain stresses within hydrides precipitated in rolled zircaloy-4 plates were determined by synchrotron X-ray diffraction experiments using an 80keV photon beam and a high-speed area detector placed in transmission geometry. Results showed large compressive stresses (360±20MPa) in the hydrides along the plate rolling direction. The origin of these stresses was investigated by performing hydride dissolution\\/precipitation in situ for thermal

J. R. Santisteban; M. A. Vicente-Alvarez; P. Vizcaíno; A. D. Banchik; J. D. Almer

2010-01-01

367

Hydride-induced embrittlement and fracture in metals—effect of stress and temperature distribution  

Microsoft Academic Search

A 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. Material damage and crack growth are also simulated by using de-cohesion model, which takes into account the time variation

A. G. Varias; A. R. Massih

2002-01-01

368

Simulation and experimental validation of a hydrogen storage tank with metal hydrides  

Microsoft Academic Search

This paper presents a hydrogen storage system using metal hydrides for a combined heat and power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (3.5bar) and low temperatures (75?C: fuel cell temperature).During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed

Maxime Botzung; Serge Chaudourne; Olivier Gillia; Christian Perret; Michel Latroche; Annick Percheron-Guegan; Philippe Marty

2008-01-01

369

Energy density analysis of the chemical bond between atoms in perovskite-type hydrides  

Microsoft Academic Search

Atomization energy diagram is proposed for analyzing the chemical bond in the perovskite-type hydrides such as M1MgH3 (M1=Na, K, Rb), RbCaH3, CaNiH3 and SrPdH3. The atomization energies of hydrogen and metal atoms in the hydrides are evaluated theoretically by the energy density analysis (EDA) of the total energy, and used for the construction of the atomization energy diagram. Every hydride

Yoshifumi Shinzato; Hiroshi Yukawa; Masahiko Morinaga; Takeshi Baba; Hiromi Nakai

2007-01-01

370

Failure of hydrided zircaloy-4 under equal-biaxial and plane-strain tensile deformation  

Microsoft Academic Search

The fracture behavior of unirradiated Zircaloy-4 containing either solid hydride blisters or hydrided rims has been examined for the contrasting conditions of equal-biaxial and plane-strain tensile deformation at three temperatures (25, 300, and 375 C). Cold-worked and stress-relieved Zircaloy-4 sheet containing hydride blisters shows nearly identical failure strains in equal-biaxial and plane-strain tensile deformation for a wide range of blister

A. Glendening; D. A. Koss; A. T. Motta; O. N. Pierron; R. S. Daum

2005-01-01

371

High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications  

PubMed Central

For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

Felderhoff, Michael; Bogdanovic, Borislav

2009-01-01

372

Electrochemical selenium hydride generation with in situ trapping in graphite tube atomizers  

Microsoft Academic Search

A manifold coupling continuous electrolytic hydride generation of volatile hydrides with atomization in graphite tube atomizers after in situ collection was used for Se(IV) determination. Laboratory-made thin-layer flow-through cells with lead wire (cell I) and granular lead (cell II) as the cathode material were used as the electrolytic generators of volatile selenium hydride. The automatic sampling equipment of the graphite

Jan Š??ma; Petr Rychlovský

2003-01-01

373

Hydriding of the mixed-valent compound CeRhIn: structural and magnetization studies  

Microsoft Academic Search

Mixed-valent compound, CeRhIn, having the hexagonal Fe2P-type structure and a moderate value of the Kondo temperature (TK?150 K), is found to form two distinct hydride phases. The higher hydride phase in CeRhInHy system with y?1.55 is found to be quite unstable and readily transforms to a lower hydride with y?0.55. From structural and magnetization studies, it is found that in

P. Raj; A. Sathyamoorthy; K. Shashikala; C. R. Venkateswara Rao; D. Kundaliya; S. K. Malik

2002-01-01

374

A study of the oxidation of titanium hydride powder by measurements of its electrical resistance  

NASA Astrophysics Data System (ADS)

The oxidation of titanium hydride powder by air oxygen and the influence of oxidation conditions on the degree of oxidation of hydride particles, specific gas content in the powder, and kinetics of its thermal decomposition were studied. The resistometry method was used to determine the effective activation energy of oxidation of titanium hydride by air oxygen. The content of the surface nonconducting phase formed by titanium oxide and oxohydride films under various oxidation conditions was estimated.

Tsarev, M. V.; Mokrushin, V. V.; Sten'gach, A. V.; Tarasova, A. I.; Berezhko, P. G.; Kremzukov, I. K.; Zabavin, E. V.

2010-04-01

375

Thermal diffusivity measurement of uranium–thorium–zirconium hydride  

Microsoft Academic Search

The uranium–thorium mixed zirconium hydrides of UTh4Zr10Hx (x=20, 24, 27) have been successfully fabricated without large crack by means of a Sieverts apparatus. The scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses show that UTh4Zr10Hx consist of ?-U, ThZr2Hx, and (?, ?)-ZrHx. The thermal diffusivity measurements of UTh4Zr10Hx have been performed over the temperature ranges to around 773 K

B Tsuchiya; J Huang; K Konashi; W Saiki; T Onoue; M Yamawaki

2000-01-01

376

METHOD OF MAKING DELTA ZIRCONIUM HYDRIDE MONOLITHIC MODERATOR PIECES  

DOEpatents

A method is given for preparing large, sound bodies of delta zirconium hydride. The method includes the steps of heating a zirconium body to a temperature of not less than l000 deg C, providing a hydrogen atmosphere for the zirconium body at a pressure not greater than one atmosphere, reducing the temperature slowly to 800 deg C at such a rate that cracks do not form while maintaining the hydrogen pressure substantially constant, and cooling in an atmosphere of hydrogen. (AEC)

Vetrano, J.B.

1962-01-23

377

On X-ray Emission from Highly Loaded Hydrides  

Microsoft Academic Search

X-ray emission (1-2 keV) has been observed in various experiments using electrolytic or plasma methods for loading of hydride targets such as Pd-D to atom ratios > 0.8. Intensities vary from very low-level emission up to laser-like focused beams, depending on experimental conditions(A.G. Lipson et al, JETP Letters, (submitted)). Bremsstralung during thermalization of energetic alphas\\/protons created by nuclear reactions in

George H. Miley; Heinrich Hora; Nie Luo; Andrei Lipson

2004-01-01

378

Use of mechanoactivation for obtaining hydrides of titanium aluminides  

Microsoft Academic Search

The hydrogen storage capacity of titanium aluminides Ti(Al,Nb) (?0) and Ti3 (Al,Nb) (?2) subjected to mechanoactivation has been investigated. It has been found that the mechanoactivation in a hydrogen atmosphere\\u000a makes it possible to obtain hydrides of titanium aluminides with a hydrogen concentration of up to 1.8 wt % at room temperature\\u000a without enhanced requirements for purity and pressure of

N. V. Kazantseva; N. V. Mushnikov; A. G. Popov; V. A. Sazonova; P. B. Terent’ev

2008-01-01

379

Hydride transfer versus hydrogen radical transfer in thymidylate synthase.  

PubMed

The nature of a H-transfer in the thymidylate synthase catalyzed reaction was investigated by comparison of the wild-type enzyme with the W80M mutant. The nature of the H-transfer was not affected, as indicated by intrinsic isotope effects and their temperature dependence. These findings support a single-step hydride transfer instead of a two-step radical transfer. PMID:16637621

Hong, Baoyu; Haddad, Majd; Maley, Frank; Jensen, Jan H; Kohen, Amnon

2006-05-01

380

Corrosion of AB{sub 5} metal hydride electrodes  

SciTech Connect

Metal hydride electrodes are an attractive substitute for the cadmium electrode in Cd/Ni batteries because of their relatively benign environmental impact and higher energy density. However, even though MH{sub x}/Ni batteries are currently competitive in certain applications, their full potential as cheap, reliable, energy storage devices is not yet realized: a severe penalty has been incurred in storage capacity and materials costs in order to inhibit corrosion and attain acceptable electrode cycle life. Currently there are two types of alloys which are useful as metal hydride electrodes, the AB{sub 5} and the AB{sub 2} classes of intermetallic compounds. Commercial AB{sub 5} electrodes use mischmetal, a low cost combination of rare earth elements. The B{sub 5} component remains primarily Ni but is substituted in part with Co, Mn, Al etc. The partial substitution of Ni increases thermodynamic stability of the hydride phase and corrosion resistance. Such an alloy is commonly written as MmB{sub 5} where Mm represents the mischmetal component; the B{sub 5} composition in commercial batteries is variable but electrodes consisting of MmNi{sub 3.55}Co{sub .75}Mn{sub .4}Al{sub .3} have good storage capacity and cycle life and most AB{sub 5} battery electrodes have a similar composition. The authors have been concerned with the function that individual components play in such an alloy with respect to lattice expansion, hydride stability, and surface passivation. Thus they have focused on the properties of a similar alloy, A(NiCoMnAl){sub 5} where A is La or La{sub 1{minus}x}Ce{sub x}. Some of their results noted here have previously appeared in separate publications; the purpose of this paper is to combine them with new data to give a more coherent and complete whole.

Adzic, G.D.; Johnson, J.R.; Mukerjee, S.; McBreen, J.; Reilly, J.J. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science

1997-11-01

381

Volume dependent vibrational properties of cerium hydrides from first principles  

Microsoft Academic Search

We have performed an ab initio study of structural, volume-dependent elastic and lattice dynamical properties of rare-earth metal-hydrides CeH2 and CeH3. The calculations have been carried out within the density functional theory and linear response formalism using norm-conserving pseudopotentials and a plane-wave basis. The hydrogen incorporation into the octahedral sites of the cubic CeH2 to obtain CeH3 leads to stiffening

Tanju Gürel; Resul Eryi?it

2009-01-01

382

Angular Correlation of Positron-Annihilation Radiation from Cerium Hydride  

Microsoft Academic Search

The angular correlation of positron-annihilation radiation from cerium hydride was measured for hydrogen concentrations in the range H\\/Ce = 1.8–2.8. The angular correlations were found to be broader than that from cerium metal and to increase in width with increasing hydrogen concentration in a manner consistent with the screened protonic model of the electronic structure. The anionic model does not

M. P. Chouinard; D. R. Gustafson; R. C. Heckman

1969-01-01

383

Gas chromatographic separation of hydrogen isotopes using metal hydrides  

SciTech Connect

A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

Aldridge, F.T.

1984-05-09

384

Structural and magnetic ordering in the cerium hydride (abstract)  

Microsoft Academic Search

Depending on the H concentration at the octahedral (O) sites, x(O), various tetragonal phases, due to H ordering, are observed in the Ce hydride at low temperatures. While our single crystal work showed that the tetragonal phase for H\\/Ce≊2.7, corresponding to x(O)≊3\\/4, is only stable in a region of x(O)=±0.05, the other one was believed to be caused by a

R. R. Arons; J. K. Cockcroft; E. Ressouche

1994-01-01

385

The Development of a Compact Refrigeration System using Metal Hydrides  

NASA Astrophysics Data System (ADS)

The MH refrigeration systems are regarded as important and compact ones for solving energy and environmental issues. Our purposes are to develop the compact refrigeration system for the vending machine and the show case using MH, and to attain a refrigeration temperature of 243K by using a heat source of 403?423K. The kinetics of MH hydriding and dehydriding reactions is of importance relative to their practical use as a refrigerator system. The kinetics of the reaction between hydrogen and MHHigh (Ti0.18Zr0.84Cr1.0FeO.7Mn0.3CuO.057)has been followed in this paper. A relatively rapid absorption of hydrogen takes place for values of relative composition to about 0.3?0.4. It is evident that a hydrogen diffusion plays a minor role during this stage, as that part of the metal not covered by hydride is always in contact with hydrogen. The direct chemical reaction between the hydrogen and the exposed metal surface is therefore postulated as the rate-controlling process. The rate of the reaction then decreases, and for values of relative composition above about 0.8, the reaction becomes slow. After the metal particles have been completely covered by a hydride layer, the transport of materials through the layer by diffusion becomes rate controlling process

Bae, Sang-Chul; Ogawa, Masahito; Katsuta, Masafumi

386

Dehydrogenation catalyst for optical organic-hydride detection  

NASA Astrophysics Data System (ADS)

The leak detection of organic hydrides, which are approvable carriers to store and transport hydrogen, has importance for safe usage. The potential use of hydrogen gasochromic materials was investigated with the combination of dehydrogenation catalysts for this purpose. The dehydrogenation activity of catalytic metals which are Pt, Pd, Rh, Ir, Ni, and Cu, was determined with loading alumina pellets with a content of 1 wt.% for 5% cyclohexane as a organic hydride in N 2 gas. The hydrogen generation was observed over 100 °C for Pt and Pd, and over 150 °C for Rh and almost negligible for other metals. The Pt and Pd were selected as dehydrogenation catalysts to be combined with WO 3 of hydrogen gasochromic materials. The WO 3 films covered with Pt and Pd were prepared by a reactive RF-sputtering. The coloration of as prepared film was observed over 150 °C when exposing with cyclohexane in N 2 gases. We found that Pt/WO 3 and Pd/WO 3 films heated to around 200 °C were applicable to optical organic-hydride sensors.

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

2011-02-01

387

Experimental studies on the behaviours of hydride heat storage system  

NASA Astrophysics Data System (ADS)

Experimental examinations and a lumped system model are used to describe the heat transfer characteristics in the design of a single tube type metal hydride heat storage vessel. The apparatus studied was fed heat by water vaporized by an electric furnance with a 3 kWh x 2 capacity. An annular tube in the middle of the reactor vessel contained the metal hydride (Mg2Ni), which was washed with hydrogen gas. Measurements were taken of the heat transfer medium temperature, H2 flow rate, and temperature responses at sites in the hydride bed. The numerical model was constructed assuming that no pressure gradient was present in the heat storage medium bed, the temperature was uniform throughout the bed, and material characteristics were independent of pressure and temperature encountered. The bed temperature was found to be uniform in the generation and absorption phases, although the latter took longer to stabilize. The lumped parameter model developed is shown to acceptably model the performance of a single tube type heat storage vessel in terms of heat transfer efficiency.

Kawamura, M.; Ono, S.; Higano, S.

388

Hydride Molecules in the Local Universe and Beyond  

NASA Astrophysics Data System (ADS)

The Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory (HSO) is providing invaluable data on hydride molecules in the interstellar medium within the Milky Way and nearby galaxies. I would like to present some of the key results from hydride studies with Herschel/HIFI instrument such as the first observations at high spectral resolution of the fundamental J = 1 - 0 rotational transition of hydrogen fluoride (HF) at 1.232 THz, and the discovery of its ubiquitous nature within the ISM of the Milky Way galaxy, first detection of some Cl-bearing molecules in diffuse medium towards a bright submillimeter continuum and the water abundance enhancement towards the Galactic Center. The data that I will present is from the guaranteed time key programs, Probing Interstellar Molecules with Absorption lines Studies (PRISMAS) and Herschel/HIFI Observations of EXtraOrdinary Sources (HEXOS). Following-up on the Herschel discovery on molecular hydrides within the ISM of the Milky Way galaxy, we are conducting a search for the fundamental rotation lines of HF and H2O towards nearby galaxies with Herschel/HIFI and luminous lensed high-redshiftd galaxies with strong submillimeter continuum with the Caltech Submillimeter Observatory (CSO) and the Plateau de Bure Interferometer (PdBI) toward. Results and interpretation from these observations will be presented at the AAS.

Monje, Raquel

2012-05-01

389

Superconductive sodalite-like clathrate calcium hydride at high pressures.  

PubMed

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 H(2) fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particle-swam optimization structural search, we show that in the stoichiometry CaH(6) 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 H(2) of electrons donated by Ca forming an "H(4)" 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 CaH(6). A superconducting critical temperature (T(c)) 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

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

2012-04-06

390

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

SciTech Connect

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.

Nasise, J.E.

1988-01-01

391

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

NASA Astrophysics Data System (ADS)

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.

Allen, Gregory B.; Kerr, Matthew; Daymond, Mark R.

2012-11-01

392

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

SciTech Connect

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.

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

2012-10-23

393

Mercury’s Sodium Exosphere: Up-Close with MESSENGER  

NASA Astrophysics Data System (ADS)

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) UltraViolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbiting Mercury provides the first up-close look at the planet’s sodium exosphere. We have observed the exosphere from orbit almost daily for more than 9 Mercury years and have used these data to make estimates of sodium density and temperature for the equatorial dayside and south pole. We find that the density varies over time but that this variability repeats itself: the density and temperature at a given local time and true anomaly (time of year) are nearly identical from one Mercury year to the next. The bulk of the exosphere has a temperature of around 1200 K, consistent with photon-stimulated desorption, although a more energetic and as-yet uncertain mechanism populates the relatively tenuous high altitudes and tail. The density varies in a manner consistent with transport caused by radiation pressure, which acts to push sodium away from noon and toward the terminators. Radiation pressure transport is one aspect of the exosphere identified by ground based observers over the last three decades. Some interpretations of their data, however, are inconsistent with our analysis of the orbital data. For example, they conclude that the exosphere has a persistent dawn/dusk asymmetry with more sodium at dawn, while we see a dawn/dusk asymmetry only during half of Mercury’s year. Many ground-based observers also reported frequent brightenings of polar sodium emissions and attributed them to episodic ion flux. Our limited observations of the south polar region show primarily seasonal, rather than episodic, variability.

Cassidy, Timothy A.; Merkel, A. W.; McClintock, W. E.; Burger, M. H.; Killen, R. M.; Vervack, R. J.; Sarantos, M.

2013-10-01

394

Phytoremediation of Ionic and Methyl Mercury Pollution  

SciTech Connect

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to control the chemical speciation, electrochemical state, transport, and aboveground binding of mercury in order to manage this toxicant.

Meagher, Richard B.

2005-06-01

395

Assessment of mercury presence and exposure in a lighthouse with a mercury drive system  

Microsoft Academic Search

It is common practice for lighthouses with large Fresnel lenses to use mercury baths as a low-friction rotation mechanism. Some recent acute mercury poisonings and incidents of abnormal behavior in lighthouse keepers have drawn attention to the potential for chronic mercury poisoning in these workplaces. This study evaluated the distribution of mercury in a lighthouse on the Canadian west coast,

C. Vannetten; K. E. Teschke

1988-01-01

396

Mercury levels in fishes from some Missouri lakes with and without known mercury pollution  

Microsoft Academic Search

Mercurial fungicides used in golf greens can lead to elevated mercury levels in fish from lakes receiving greens drainage. The largemouth bass is the most sensitive indicator with levels ranging from 1-7 mg mercury\\/g of wet tissue in fish taken from lakes that receive drainage from treated greens. Many lakes with no known source of mercury contamination produce bass that

S. R. Koirtyohann; R. Meers; L. K. Graham

1974-01-01

397

Mercury after three MESSENGER flybys  

NASA Astrophysics Data System (ADS)

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) space-craft, developed under NASA's Discovery Program, is the first space probe to visit the planet Mercury in more than 30 years. MESSENGER flew by the innermost planet twice in 2008 and once last fall. The flybys confirmed that Mercury's internal magnetic field is dominantly dipolar, with a vector moment closely aligned with the spin axis. MESSENGER detected mag-nesium in Mercury's exosphere, demonstrated that Mercury's anti-sunward neutral tail contains multiple species, and revealed that the distributions of sodium, calcium, and magnesium in the exosphere and tail vary differently with latitude, time of day, and Mercury's position in or-bit, signatures of multiple source processes. MESSENGER's laser altimeter showed that the equatorial topographic relief of Mercury exceeds 5 km, revealed an equatorial ellipticity aligned with the ellipticity in Mercury's gravitational potential, and documented the form of numer-ous impact craters and fault scarps. MESSENGER images provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. In addition, newly imaged lobate scarps and other tectonic landforms support the hypothesis that Mercury contracted globally in response to interior cooling. The ˜1500-km-diameter Caloris basin, viewed in its entirety for the first time by MESSENGER, was the focus for concentrations of volcanic cen-ters, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation; smooth plains interior and exterior to the basin are demonstrably younger than the basin-forming event. The ˜700-km-diameter Rembrandt basin, less volcanically infilled than Caloris, was likewise a focus for concentrated magmatic and deformational activity. A ˜290-km-diameter basin contains interior plains that are among the youngest volcanic material on the planet. The nearly global observations of Mercury surface units distinguishable by color and composition enforce the significance of the largely volcanic smooth plains, which occupy ˜40% of the surface area, and of low-reflectance material, occupying ˜15% of the surface area and located primarily in deposits excavated by impact, consistent with having originated at depth. Reflectance spectra show no evidence for FeO in surface silicates, and reflectance and color imaging observations support earlier inferences that Mercury's surface material consists dominantly of iron-poor, calcium-magnesium silicates with an admixture of spectrally neutral opaque minerals. In support of the hypothesis that those opaque minerals are iron-titanium oxides, MESSENGER's neutron spectrometer showed that the surface abundance of iron plus titanium is comparable to that of some lunar mare regions. MESSENGER's three flybys re-vealed that Mercury's magnetosphere is more dynamic and responsive to imposed solar wind conditions than that of any other solar system body, and they showed that the planet of-ten experiences conditions favorable to direct impact of solar wind plasma onto the surface, an important contributor to Mercury's exosphere and space weathering of surface materials. MESSENGER is now on course for insertion into orbit about Mercury in March 2011, and one Earth-year of orbital observations is planned for the remainder of the nominal mission.

Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Prockter, Louise M.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Zuber, Maria T.

398

Hydrogen storage and evolution catalysed by metal hydride complexes.  

PubMed

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

Fukuzumi, Shunichi; Suenobu, Tomoyoshi

2013-01-01

399

Surface-mediated thin terbium hydride film formation.  

PubMed

This work was performed to study the correlation between the surface and bulk phenomena that occur during H(2) interaction with terbium, leading to three-hydride TbH(x) (x approximately 3) formation. This reaction is accompanied by the transition of the original metal into a semiconductor. It was found that thin films are particularly useful for such studies. Measurements of work function changes DeltaPhi(H/Tb) were chosen to illustrate the surface phenomena, and the relative electrical resistance R(H/Tb)/R(0) and light transparency T(H/Tb)/T(0) correspond to the bulk properties. Additionally, BET experiments were performed to determine the influence of three-hydride formation on the area of a thin Tb film. It was observed at 298 K that a precursor state of the adsorbate arose at the beginning of the reaction, when (H/Tb < 0.1), decreasing the work function by DeltaPhi = 12 mV. A higher uptake of hydrogen caused an increased work function, followed by DeltaPhi transients. This has been interpreted as local hydride formation on the surface and its expansion into the bulk, until a concentration of H/Tb approximately 3 was reached. TbH(x) (x approximately 3) formation resulted in DeltaPhi = approximately 200 mV and an increase in the thin film area by a factor of approximately 3. These phenomena were accompanied by characteristic changes in the bulk properties. The light-reflecting thin Tb film was transformed into a transparent hydride, with an approximately 23-fold increase in R/R(0). At 78 K, only a small amount of hydrogen (H/Tb = 0.13) was consumed, leading to DeltaPhi = -23 mV. This uptake is stable up to 100 K. Increasing the temperature above this value resulted in the additional large absorption of hydrogen. This could suggest the formation of a low-temperature surface phase of the hydride. PMID:20078125

Knor, Marek; Nowakowski, Robert; Nowicka, Ewa; Du?, Ryszard

2010-03-01

400

An Acute Mercuric Mercury Poisoning: Chemical Speciation of Hair Mercury Shows a Peak of Inorganic Mercury Value  

Microsoft Academic Search

A woman ingested a dose of sublimate (approximately 0.9 g) in an attempted suicide. She survived and recovered in response to a combination of therapies including chelate (BAL) therapy, plasma exchange, haemodialysis and peritoneal dialysis.Serum inorganic mercury concentration, urinary inorganic mercury excretion and hair inorganic and organic mercury and selenium concentrations, along the length from the scalp to the distal

T. Suzuki; T. Hongo; N. Matsuo; H. Imai; M. Nakazawa; T. Abe; Y. Yamamura; M. Yoshida; H. Aoyama

1992-01-01

401

Environmental and health aspects of lighting: Mercury.  

National Technical Information Service (NTIS)

Most discharge lamps, including fluorescent lamps, metal halide lamps, and high pressure sodium lamps, contain Mercury, a toxic chemical. Lighting professionals need to be able to respond to questions about the direct hazards of Mercury from accidentally ...

R. Clear S. Berman

1993-01-01

402

MERCURY IN AN INSECTIVOROUS BIRD SPECIES  

EPA Science Inventory

Mercury distributions within ecosystems must be examined to determine exposure and risk to wildlife in specific areas. In the current study, we examined exposure and uptake of mercury in nestling prothonotary warblers (protonitaria citrea) inhabiting two National Priority List (...

403

Calibration of Lemair Mercury Vapor Detector.  

National Technical Information Service (NTIS)

A project was initiated to calibrate the Lemair Mercury Vapor Detector. The detector was calibrated using the sampling and generating procedure reported by Nelson. A modification of the analytical procedure was necessary to insure complete mercury recover...

E. J. Smith P. Diamond

1968-01-01

404

2006 mercury control technology conference. Proceedings  

SciTech Connect

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.

NONE

2006-07-01

405

The evaporation of a drop of mercury  

NASA Astrophysics Data System (ADS)

The evaporative rates of two drops of mercury at room temperature are determined experimentally and theoretically. The resulting mercury vapor levels are estimated and measured, compared with the OSHA permissible exposure limit, and found to be small by comparison.

Winter, Thomas G.

2003-08-01

406

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....

407

MERCURY CONTAMINATION STANDARDS FOR MARINE ENVIRONMENTS  

EPA Science Inventory

Selected technical literature on biological and ecological effects of mercury compounds on marine and estuarine biota is reviewed. Potential and actual hazards to public health through marine vectors are considered. Within this framework, approaches for establishing mercury conta...

408

Revisiting collisional stripping of Mercury's mantle  

NASA Astrophysics Data System (ADS)

New constraints on Mercury's core size and mantle composition challenge the tradition giant-impact hypothesis for Mercury's iron enrichment. We combine geophysical, astrophysical and geochemical modeling to illustrate an alternative giant-impact scenario.

Riner, M. A.; Desch, S. J.; Taylor, G. J.

2011-10-01

409

Mercury Compounds in Drugs and Food.  

National Technical Information Service (NTIS)

The Food and Drug Administration (FDA) is required to: (1) compile a list of drugs and foods that contain intentionally introduced mercury compounds, and (2) provide a quantitative and qualitative analysis of the mercury compounds in this list. The agency...

1999-01-01

410

Toxicity Studies of Mercury in Japan.  

National Technical Information Service (NTIS)

The author visited government departments and individual researchers. The mercury concentration had decreased within a few years after the cessation of mercury emissions to 'normal' values for non-polluted areas. However, in Minamata Bay since 1975 an inc...

T. Kjellstroem

1982-01-01

411

Method for the removal and recovery of mercury  

DOEpatents

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.

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

1997-01-01

412

Method for the removal and recovery of mercury  

DOEpatents

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.

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

1997-01-28

413

Mercury’s Tides As a Window to its Interior  

NASA Astrophysics Data System (ADS)

Measurements of the obliquity and forced librations of Mercury, along with the precise determination of the static component of the gravitational field obtained by MESSENGER, provide estimates of the polar moment of inertia of the planet and of the planet’s outer solid shell. Although these data greatly improve our knowledge of the planet’s interior, the process of inverting geodetic observations to infer the interior structure is highly non-unique, and a wide range of models are compatible with the available observations. The recent determination of the tidal component of the gravitational field, particularly the Love number k2, can provide additional constraints on the interior structure of Mercury. The orbital timescale that characterizes the tidal action of the Sun is sufficiently short that the response of materials inside Mercury is dictated both by their elastic properties and by their physical state (e.g., solid or liquid). The presence of a liquid layer below the mantle should then manifest itself in the tidal component of the gravity field. Furthermore, it has recently been suggested that a dense solid metallic layer might surround the fluid core and form the bottom of the planet’s outer solid shell. If present, this layer, depending on its thickness and material properties, may influence the tidal response of Mercury. Calculations of the tidal response for a variety of interior models for Mercury provide a basis for comparison with observations.

Padovan, Sebastiano; Margot, J. L.; Hauck, S. A., II; Solomon, S. C.

2012-10-01

414

Peat bog records of atmospheric mercury deposition  

Microsoft Academic Search

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

Poul Pheiffer Madsen

1981-01-01

415

ROLE OF MERCURY IN SVARNA VANGA PREPARATION  

PubMed Central

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.

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

1985-01-01

416

Role of mercury in svarna vanga preparation.  

PubMed

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

Sharma; Gyaneshwar; Joshi, D; Pandey, V B; Aryya, N C

1985-04-01

417

Phytoremediation of Ionic and Methyl Mercury Pollution  

SciTech Connect

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

Meagher, Richard B.

2004-12-01

418

Mercury toxicity awareness in the nursery.  

PubMed

Mercury vapor may pose an environmental risk to the developing newborn. Two case reports from Southeastern urban hospitals are presented describing potential problem identification, air sampling methods, and recommendations for minimizing the risk. Current convenience sampling of hospital nurseries revealed 11% to 20% use of mercury-filled glass thermometers. Because this use continues to place infants at risk, health care provides must be educated in removing mercury to the extent possible and in ensuring a mechanism for cleaning mercury spills. PMID:9134514

Thigpen, J; Sexson, W R

419

CFD Modeling for Mercury Control Technology  

Microsoft Academic Search

Compliance with the Clean Air Mercury Rule will require implementation of dedicated mercury control solutions at a significant portion of the U.S. coal-fired utility fleet. Activated Carbon Injection (ACI) upstream of a particulate control device (ESP or baghouse) remains one of the most promising near-term mercury control technologies. The DOE\\/NETL field testing program has advanced the understanding of mercury control

2006-01-01

420

The isolation and initial characterization of mercury resistant chemolithotrophic thermophilic bacteria from mercury rich geothermal springs  

Microsoft Academic Search

Mercury rich geothermal springs are likely environments where mercury resistance is critical to microbial life and where microbe-mercury\\u000a interactions may have evolved. Eleven facultative thermophilic and chemolithoautotrophic, thiosulfate oxidizing bacteria were\\u000a isolated from thiosulfate enrichments of biofilms from mercury rich hot sulfidic springs in Mount Amiata, Italy. Some strains\\u000a were highly resistant to mercury (?200 ?M HgCl2) regardless of its presence

Aspassia D. Chatziefthimiou; Melitza Crespo-Medina; Yanping Wang; Costantino Vetriani; Tamar Barkay

2007-01-01

421

Mercury from mineral deposits and potential environmental impact  

USGS Publications Warehouse

Mercury deposits are globally distributed in 26 mercury mineral belts. Three types of mercury deposits occur in these belts: silica-carbonate, hot-spring, and Almaden. Mercury is also produced as a by-product from several types of gold-silver and massive sulfide deposits, which account for 5% of the world's production. Other types of mineral deposits can be enriched in mercury and mercury phases present are dependent on deposit type. During processing of mercury ores, secondary mercury phases form and accumulate in mine wastes. These phases are more soluble than cinnabar, the primary ore mineral, and cause mercury deposits to impact the environment more so than other types of ore deposits enriched in mercury. Release and transport of mercury from mine wastes occur primarily as mercury-enriched particles and colloids. Production from mercury deposits has decreased because of environmental concerns, but by-product production from other mercury-enriched mineral deposits remains important.

Rytuba, J. J.

2003-01-01

422

Mercury and selenium interaction: A review  

SciTech Connect

This paper reviews studies on mercury and selenium interaction. It includes the effects of selenium on mercury toxicity on the organism, organ/tissue, and subcellular levels. The paper also touches on possible mechanisms for the protective action of selenium against mercury toxicity and deals briefly with the synergism between the two elements. 71 references.

Cuvin-Aralar, M.L.; Furness, R.W. (Binangonan Freshwater Station, Southeast Asian Fisheries Development, Center Aquaculture Department, Rizal (Philippines))

1991-06-01

423

Mercury-resistant bacteria and petroleum degradation  

Microsoft Academic Search

The concentration of mercury in water and sediment and in the oil extracted from water and sediment was determined for samples collected in Colgate Creek, located in Baltimore Harbor of the Chesapeake Bay. The concentration of mercury in the oil was 4000 times higher than in sediment and 300,000 times higher than in water samples. The mercury-resistant bacterial populations of

J. D. Walker; R. R. Colwell

1974-01-01

424

Structural basis of aquaporin inhibition by mercury  

PubMed Central

The aquaporin family of channels was defined based on the inhibition of water transport by mercurial compounds. Despite the important role of mercurials, little is known about the structural changes involved upon mercury binding leading to channel inhibition. To elucidate the mechanism we designed a mutant, T183C, of aquaporin Z (AqpZ) patterned after the known mercury-sensitive site of aquaporin 1 (AQP1) and determined the x-ray crystal structures of the unbound and mercury blocked states. Superposition of the two structures shows no conformational rearrangement upon mercury binding. In the blocked structure, there are two mercury sites – one bound to Cys183 and occluding the pore, and a second, also bound to the same cysteine but found buried in an interstitial cavity. To test the mechanism of blockade we designed a different mutant, L170C, to produce a more effective mercury block at the pore site. In a dose-response inhibition study, this mutant was 20 times more sensitive to mercury than wild-type AqpZ and 4 times more sensitive than T183C. The x-ray structure of L170C shows four mercury atoms at, or near, the pore site defined in the T183C structure and no structural change upon mercury binding. Thus, we elucidate a steric inhibition mechanism for this important class of channels by mercury.

Savage, David F.; Stroud, Robert M.

2012-01-01

425

Coping with uncertainties of mercury regulation  

SciTech Connect

The thermometer is rising as coal-fired plants cope with the uncertainties of mercury regulation. The paper deals with a diagnosis and a suggested cure. It describes the state of mercury emission rules in the different US states, many of which had laws or rules in place before the Clean Air Mercury Rule (CAMR) was promulgated.

Reich, K. [Wolf-Block, Boston, MA (United States)

2006-09-15

426

Mercury Thermometer Replacements in Chemistry Laboratories  

ERIC Educational Resources Information Center

The consequences of broken mercury-in-glass thermometers in academic laboratories results in various health and environmental hazards, which needs to be replaced, by long-stem digital thermometers and non-mercury glass thermometers. The factors that should be considered during the mercury replacement process are types of applications in the…

Foster, Barbara L.

2005-01-01

427

Mercury and selenium content of Taiwanese seafood  

Microsoft Academic Search

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

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

2011-01-01

428

Control of Mercury Pollution in Sediments.  

National Technical Information Service (NTIS)

Methods are described for controlling pollution from mercury-laden sediment deposits on the bottom of streams and lakes. Five sediment samples containing from 6 ppm to 500 ppm mercury were investigated. A variety of methods for recovering the mercury valu...

C. C. Harlin

1972-01-01

429

Selenium's importance in regulatory issues regarding mercury  

Microsoft Academic Search

Current seafood safety and health risk assessment criteria use mercury concentrations as their sole basis. This unfortunate limitation omits consideration of selenium, an essential trace element that appears to be the primary molecular target of mercury toxicity. Although selenium has been recognized for decades as a means of counteracting mercury toxicity, its effects have often been overlooked or misunderstood. Experimental

Laura J. Raymond; Nicholas V. C. Ralston

2009-01-01

430

Mercury baseline levels in Flemish soils (Belgium)  

Microsoft Academic Search

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

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

2005-01-01

431

Mercury concentrations in cattle from NW Spain  

Microsoft Academic Search

Mercury is a toxic metal that is released into the environment as a result of various industrial and agricultural processes. It can be accumulated by domestic animals and so contaminate human foodstuffs. To date, there is no information on mercury residues in livestock in Spain and the aim of the present study was to quantify the concentrations of mercury in

M. López Alonso; J. L. Benedito; M. Miranda; C. Castillo; J. Hernández; R. F. Shore

2003-01-01

432

Don't Mess with Mercury  

NSDL National Science Digital Library

In this short video from the U.S. Environmental Protection Agency, learn how to avoid mercury hazards. Graphics and animations illustrate the liquid appearance of elemental mercury and warn viewers about the dangers of exposure. Hear about how you should not touch mercury and how it can contaminate objects in the home. A background essay, discussion questions, and standards correlations are also provided.

2010-08-31

433

40 CFR 721.10068 - Elemental mercury.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Elemental mercury. 721.10068 Section 721.10068...Substances § 721.10068 Elemental mercury. (a) Barometer means an instrument...1) The chemical substance elemental mercury (CAS. No. 7439-97-6) is...

2013-07-01

434

Mercury and selenium interaction: A review  

Microsoft Academic Search

This paper reviews studies on mercury and selenium interaction. It includes the effects of selenium on mercury toxicity on the organism, organ\\/tissue, and subcellular levels. The paper also touches on possible mechanisms for the protective action of selenium against mercury toxicity and deals briefly with the synergism between the two elements. 71 references.

M. L. Cuvin-Aralar; R. W. Furness

1991-01-01

435

What's all the Fuss about Mercury?  

ERIC Educational Resources Information Center

|Mercury tends to vaporize when exposed to air. The warmer the air, the more quickly it vaporizes. Although swallowing mercury can be a problem, the greater risk results from inhalation and skin absorption. Symptoms and health-related problems can result within hours of exposure. Spilled mercury settles in cracks and absorbent material such as…

Roy, Ken

2004-01-01

436

Shedding some light on mercury lamps  

NSDL National Science Digital Library

This Environmental Science and Technology article discusses the problem created when mercury-containing lamps are not recycled. The article provides statistics on the amount of bulbs being disposed and the quantity of mercury that may be improperly disposed. It also suggests possible solution to the potentially hazardous mercury disposal. The article features in-text links to related topics.

Online, Environmental S.; Society, American C.

437

Mercury Thermometer Replacements in Chemistry Laboratories  

ERIC Educational Resources Information Center

|The consequences of broken mercury-in-glass thermometers in academic laboratories results in various health and environmental hazards, which needs to be replaced, by long-stem digital thermometers and non-mercury glass thermometers. The factors that should be considered during the mercury replacement process are types of applications in the…

Foster, Barbara L.

2005-01-01

438

Mercury's Exosphere Observation Using Espadons\\/CFHT  

Microsoft Academic Search

Before the arrival of Messenger at Mercury in 2008, the only source of information available on Mercury's environment is observations done from ground based observatories. These observations provided a now large data set on Mercury's exosphere and in particular of its sodium component originally discovered by Potter et al. (Science, 1985). Two other elements have been discovered in the same

Alain Doressoundiram; F. Leblanc; C. Foellmi

2006-01-01

439

High resolution observations of Mercury's exosphere  

Microsoft Academic Search

Before the arrival of Messenger at Mercury in 2008 the only source of information available on Mercury s environment is observations done from ground based observatories These observations provided a now large data set on Mercury s exosphere and in particular of its sodium component originally discovered by Potter et al Science 1985 Two other elements have been discovered in

A. Doressoundiram; F. Leblanc; C. Foellmi

2006-01-01

440

Mercury's exosphere: A possible source for Na  

Microsoft Academic Search

Many ground-based observations of Na in Mercury's surface-bounded exosphere have been made and continued to be made in an effort to understand the sources, sinks, and distribution of Na around Mercury. These time consuming and costly efforts are made to better understand the physical processes on and around Mercury. A big step would be to discover an actual source of

Ann L. Sprague; Steven S. Massey

2007-01-01

441

Imaging During MESSENGER's Second Flyby of Mercury  

Microsoft Academic Search

During MESSENGER's second flyby of Mercury on October 6, 2008, the Mercury Dual Imaging System (MDIS) will acquire 1287 images. The images will include coverage of about 30% of Mercury's surface not previously seen by spacecraft. A portion of the newly imaged terrain will be viewed during the inbound portion of the flyby. On the outbound leg, MDIS will image

N. L. Chabot; L. M. Prockter; S. L. Murchie; M. S. Robinson; N. R. Laslo; H. K. Kang; S. E. Hawkins; R. M. Vaughan; J. W. Head; S. C. Solomon

2008-01-01

442

The fate of coal mercury during combustion  

Microsoft Academic Search

The fate of the mercury content of four UK coals has been investigated using a 1 MWth Combustion Test Facility (CTF). The results demonstrate that the mercury retention in dust is related to the carbon content of the dust, with increasing retention as carbon levels increase. Conversely, as carbon levels decrease, vapour phase mercury emissions increase. The measurements also showed

W. H Gibb; F Clarke; A. K Mehta

2000-01-01

443

The Thermal Evolution of Mercury  

NASA Astrophysics Data System (ADS)

At first sight Mercury and Moon are superficially very much alike. Craters are the dominant landform. However, Mercury and Moon differ dramatically in detail. Mercury is brighter (higher albedo) and does not show the contrast of dark maria versus bright highlands. So far, no fresh lava flows of basaltic material, which are rich in heavy elements like iron or titanium have been seen on Mercury's surface. The most striking feature is probably the unusually high density of Mercury, which among other theories could be interpreted as a result of a catastrophic impact event, during which the already differentiated planet's mantle was removed. Since the upcoming space missions BEPI COLOMBO an MESSENGER will provide new detailed measurements in the next years we started developing some model results to allow for allow some anticipation of the measured data. The interior of Mercury is not well known and the current knowledge is based on data obtained during the Mariner 10 mission. In this work we present new models of the thermal evolution of Mercury, obtained with a fully three dimensional spherical shell convection code. The viscosity depends strongly on the azimuthally averaged temperature. Due to the weak constraints of other important parameters (e.g. sulfur content of the core, mantle rheology, amount and distribution of radiogenic heat sources, planetary contraction, thermal conductivity, etc) numerous models are required to understand the importance and influence of the mentioned variables. In a first attempt we want to understand the basic characteristics of the cooling behaviour of the hermean mantle. Furthermore we investigate, how the the thermal evolution of Mercury differs from those of other terrestrial planets. Compared to the Moon Mercury lacks of 'fresh' lava flows at the surface. Pictures taken during the first MESSENGER flybys show features like lava flows, but they look at first sight very similar to the surrounding rocks. This rises the question after partial melt evolution in the mantle. Therefore we also investigate to what extent and how long a molten zone in the mantle could have survived.

Ziethe, Ruth

444

Mercury Continuous Emmission Monitor Calibration  

SciTech Connect

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.

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

2009-03-12

445

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

PubMed Central

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.

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

446

An 'ab initio' Gaussian Orbital Calculation of the (100) Surface of Crystalline Lithium Hydride  

Microsoft Academic Search

Ab ab initio computation has been performed for the (100) face of a lithium hydride ionic crystal. The computation follows a similar computation performed earlier for an infinite crystal of lithium hydride. A simple wavefunction of a type proposed by A. A. Frost was used in which pairs of electrons are assigned to orbitals described by simple spherical Gaussian functions,

W. D. Erickson; J. W. Linnett

1972-01-01

447

Analysis of hydrogen storage in metal hydride tanks introducing an induced phase transformation  

Microsoft Academic Search

Hydrogen absorption in a metal hydride tank is generally studied based on a heat and mass transfer analysis. The originality of this investigation is that the phase transformation from a solid (? phase) to hydride (? phase) solution is included in the hydrogen absorption mechanism. Toward this end, a modelling of the equilibrium pressure, composition (absorbed or desorbed hydrogen atoms

Germain Gondor; Christian Lexcellent

2009-01-01

448

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

SciTech Connect

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.

Chung, H. M.

2000-04-03

449

Hydrogen storage material and process using graphite additive with metal-doped complex hydrides  

DOEpatents

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

Zidan, Ragaiy (Aiken, SC); Ritter, James A. (Lexington, SC); Ebner, Armin D. (Lexington, SC); Wang, Jun (Columbia, SC); Holland, Charles E. (Cayce, SC)

2008-06-10

450

Heat\\/mass flow enhancement system for a metal hydride assembly. Final report  

Microsoft Academic Search

Southern California Gas Company and Solar Turbines Incorporated are cooperating in the development and demonstration of a metal hydride\\/chemical heat pump (MHHP). In the design of the MHHP, heat transfer was considered to be the key technical study area. The goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger\\/containment assembly. Phase I

Argabright

1985-01-01

451

Heat-mass flow enhancement system for a metal hydride assembly  

Microsoft Academic Search

Southern California Gas Company and Solar Turbines Incorporated are cooperating in the development and demonstration of a metal hydride\\/chemical heat pump (MHHP). In the design of the MHHP, heat transfer was considered to be the key technical study area. The goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger\\/containment assembly. Phase 1

T. A. Argabright

1985-01-01

452

Hydride precipitation and its influence on mechanical properties of notched and unnotched Zircaloy-4 plates  

NASA Astrophysics Data System (ADS)

The hydride formation and its influence on the mechanical performance of hydrided Zircaloy-4 plates containing different hydrogen contents were studied at room temperature. For the unnotched plate samples with the hydrogen contents ranging from 25 to 850 wt. ppm, the hydrides exerted an insignificant effect on the tensile strength, while the ductility was severely degraded with increasing hydrogen content. The fracture mode and degree of embrittlement were strongly related to the hydrogen content. When the hydrogen content reached a level of 850 wt. ppm, the plate exhibited negligible ductility, resulting in almost completely brittle behavior. For the hydrided notched plate, the tensile stress concentration associated with the notch tip facilitated the hydride accumulation at the region near the notch tip and the premature crack propagation through the hydride fracture during hydriding. The final brittle through-thickness failure for this notched sample was mainly attributed to the formation of a continuous hydride network on the thickness section and the obtained very high hydrogen concentration (estimated to be 1965 wt. ppm).

Wang, Zhiyang; Garbe, Ulf; Li, Huijun; Harrison, Robert P.; Toppler, Karl; Studer, Andrew J.; Palmer, Tim; Planchenault, Guillaume

2013-05-01

453

LOW-TEMPERATURE MAGNETIC STUDIES OF URANIUM HYDRIDE, URANIUM DEUTERIDE, AND URANIUM DIOXIDE  

Microsoft Academic Search

A study of magnetization as a function of temperature and magnetic field ; has been carried out for uranium hydride, uranium deuteride, and uranium dioxide ; at temperatures from 300 deg K to 1.3 deg K and in magnetic fields from 60,000 ; gauss down to zero field. The apparent saturation magnetization for the samples ; of beta-uranium hydride used

Warren Henry

1958-01-01

454

FABRICATION AND PROPERTIES OF URANIUM-ZIRCONIUM HYDRIDE FUEL ELEMENTS FOR TRIGA REACTORS  

Microsoft Academic Search

The melting, casting, extrusion, and machining of 8 wt.% U and 92 wt.% ; Zr alloy are described; the assembly of the hydrided alloy into a fuel element is ; described. The fabrication of the uranium -zirconium hydride fuel materials was ; accomplished with exceptionally high yields, resulting in relatively inexpensive ; fuel elements. It was found that the use

W. P. Wallace; M. T. Simnad; B. Turovlin

1958-01-01

455

The effect of N 2 + and C + implantation on uranium hydride nucleation and growth kinetics  

Microsoft Academic Search

Hydrogen attack on uranium and uranium alloys may cause embrittlement and hydride formation that are undesirable in nuclear fuel technology. Implantation of the uranium surface by a high dose of energetic ions modifies the surface in a way that delays the hydrogen attack and slows the growth rate of the hydride. The implanted surfaces also exhibited better passivation to air

R Arkush; M Brill; S Zalkind; M. H Mintz; N Shamir

2002-01-01

456

Mathematical model of metal-hydride hydrogen tank with quick sorption  

Microsoft Academic Search

In the paper we present a model of the hydrogen tank based on hydride-forming alloy powder with quick sorption. In this case we have the heat-controlling hydriding with spatial concentration redistribution. We construct the discrete model convenient for describing different shapes of tanks and configurations of cooling systems and for parallel calculating.

I. A. Chernov; I. E. Gabis

2011-01-01

457

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

Microsoft Academic Search

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

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

2012-01-01

458

Microstructure and Hydriding Studies of AB sub 5 Hydrogen Storage Compounds. Final Report.  

National Technical Information Service (NTIS)

New data on the microstructure, pressure-composition-temperature, and absorption/desorption kinetics of AB sub 5 metal hydrides are presented. The most significant result to emerge from the investigation is that many of the AB sub 5 metal hydrides, especi...

P. D. Goodell G. D. Sandrock E. L. Huston

1980-01-01

459

Hydride transfer catalysed by Escherichia coli and Bacillus subtilis dihydrofolate reductase: coupled motions and distal mutations  

PubMed Central

This paper reviews the results from hybrid quantum/classical molecular dynamics simulations of the hydride transfer reaction catalysed by wild-type (WT) and mutant Escherichia coli and WT Bacillus subtilis dihydrofolate reductase (DHFR). Nuclear quantum effects such as zero point energy and hydrogen tunnelling are significant in these reactions and substantially decrease the free energy barrier. The donor–acceptor distance decreases to ca 2.7?? at transition-state configurations to enable the hydride transfer. A network of coupled motions representing conformational changes along the collective reaction coordinate facilitates the hydride transfer reaction by decreasing the donor–acceptor distance and providing a favourable geometric and electrostatic environment. Recent single-molecule experiments confirm that at least some of these thermally averaged equilibrium conformational changes occur on the millisecond time-scale of the hydride transfer. Distal mutations can lead to non-local structural changes and significantly impact the probability of sampling configurations conducive to the hydride transfer, thereby altering the free-energy barrier and the rate of hydride transfer. E. coli and B. subtilis DHFR enzymes, which have similar tertiary structures and hydride transfer rates with 44% sequence identity, exhibit both similarities and differences in the equilibrium motions and conformational changes correlated to hydride transfer, suggesting a balance of conservation and flexibility across species.

Hammes-Schiffer, Sharon; Watney, James B

2006-01-01

460

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

Microsoft Academic Search

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

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

2007-01-01

461

Reduction of the conjugated cyclopropene bond and double bond of substituted methylenecylopropane with lithium aluminum hydride  

Microsoft Academic Search

This paper investigates the reduction of the exo- and endo-double bonds of the three-membered carbon ring with lithium aluminum hydride. It is shown that the reduction of the activated cyclopropene double bond with litihium aluminum hydride is stereospecific and leads to alcohols of the cyclopropane series even at reduced temperatures. The reaction has a high degree of regioslectivity; initial attack

I. N. Domnin; K. Dumon; M. Vidal; Vincens M

1986-01-01

462

Reduction of the conjugated cyclopropene bond and double bond of substituted methylenecyclopropane with lithium aluminum hydride  

Microsoft Academic Search

1.The reduction of the activated cyclopropene double bond with lithium aluminum hydride is stereospecific and leads to alcohols of the cyclopropane series even at reduced temperatures. The reaction has a high degree of regioselectivity; initial attack by the hydride ion occurs at the oxygen atom adjacent to the methoxycarbonyl group.2.The reduction of functionally substituted methylenecyclopropane takes place either with retention

I. N. Domnin; K. Dumon; M. Vincens; M. Vidal

1985-01-01

463

Development of metal hydride beds for sorption cryocoolers in space applications  

Microsoft Academic Search

The development of hydrogen sorption cryocoolers over the past 30 years is briefly reviewed. The behavior of the metal hydride sorbent beds used in the sorption compressors dominates both the performance and reliability of these closed-cycle Joule–Thomson cryocoolers. Improved compressor elements have been recently designed to minimize their input power requirements and to enhance hydride durability during extended temperature cycling

R BOWMANJR

2003-01-01

464

PRODUCTION OF DIBORANE BY REDUCING BORON FLUORIDE ETHYL ETHERATE WITH CALCIUM HYDRIDE  

Microsoft Academic Search

Boron trifluoride reduction by calcium hydride was analyzed as a new ; method for obtaining boron and calcium boride. The purpose of the experiment was ; to produce diborane by reducing boron trifluoride etherate by calcium hydride. ; Synthesis of diborane was achieved at temperatures near the etherate boiling ; point. Tabulated data show good yields of diborane. (R.V.J.);

V. I. Mikheeva; E. M. Fedneva; V. I. Alpatova

1960-01-01

465

HYCSOS chemical heat pump and energy conversion system based on metal hydrides  

Microsoft Academic Search

The Argonne HYCSOS system is a two hydride concept, operating as a chemical heat pump for storage and recovery of thermal energy for heating, cooling and energy conversion. Hydrogen gas is transferred from one hydride bed by solar thermal energy input at a characteristic temperature to a second bed where hydrogen is absorbed and thermal energy is released at another

I. Sheft; D. M. Gruen; G. J. Lamich

1979-01-01

466

Near Global Mosaic of Mercury  

NASA Astrophysics Data System (ADS)

In 2008 the MESSENGER spacecraft made two close flybys (M1 and M2) of Mercury and imaged about 74% of the planet at a resolution of 1 km per pixel, and at higher resolution for smaller portions of the planet. The Mariner 10 spacecraft imaged about 42% of Mercury’s surface more than 30 years ago. Combining image data collected by the two missions yields coverage of about 83% of Mercury’s surface. MESSENGER will perform its third and final flyby of Mercury (M3) on 29 September 2009. This will yield approximately 86% coverage of Mercury, leaving only the north and south polar regions yet to be imaged by MESSENGER after orbit insertion in March 2011. A new global mosaic of Mercury was constructed using 325 images containing 3566 control points (8110 measures) from M1 and 225 images containing 1465 control points (3506 measures) from M2. The M3 flyby is shifted in subsolar longitude only by 4° from M2, so the added coverage is very small. However, this small slice of Mercury fills a gore in the mosaic between the M1 and M2 data and allows a complete cartographic tie around the equator. We will run a new bundle block adjustment with the additional images acquired from M3. This new edition of the MESSENGER Mercury Dual Imaging System (MDIS) Narrow Angle Camera (NAC) global mosaic of Mercury includes many improvements since the M2 flyby in October 2008. A new distortion model for the NAC camera greatly improves the image-to-image registration. Optical distortion correction is independent of pointing error correction, and both are required for a mosaic of high quality. The new distortion model alone reduced residual pointing errors for both flybys significantly; residual pixel error improved from 0.71 average (3.7 max) to 0.13 average (1.7 max) for M1 and from 0.72 average (4.8 max.) to 0.17 average (3.5 max) for M2. Analysis quantifying pivot motor position has led to development of a new model that improves accuracy of the pivot platform attitude. This model improves the accuracy of pointing knowledge and reduces overall registration errors between adjacent images. The net effect of these improvements is an overall offset of up to 10 km in some locations across the mosaic. In addition, the radiometric calibration process for the NAC has been improved to yield a better dynamic range across the mosaic by 20%. The new global mosaic of Mercury will be used in scientific analysis and aid in planning observation sequences leading up to and including orbit insertion of the MESSENGER spacecraft in 2011.

Becker, K. J.; Robinson, M. S.; Becker, T. L.; Weller, L. A.; Turner, S.; Nguyen, L.; Selby, C.; Denevi, B. W.; Murchie, S. L.; McNutt, R. L.; Solomon, S. C.

2009-12-01

467

Toxicity of mercury and mercury compounds. May 1978-August 1989 (Citations from Pollution Abstracts). Report for May 1978-August 1989  

SciTech Connect

This bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. Mercury halides, organic mercury compounds, mercury metal, mercury vapors, and other compounds are discussed. Metabolism, toxicology, occupational exposure, symptoms of exposure, mechanisms of interaction with biological systems, demographics of mercury accumulation and poisoning, and case reports are considered. Heavy-metal pollution and bioaccumulation are referenced in related published bibliographies. (Contains 204 citations fully indexed and including a title list.)

Not Available

1990-01-01

468

The three modern faces of mercury.  

PubMed Central

The three modern "faces" of mercury are our perceptions of risk from the exposure of billions of people to methyl mercury in fish, mercury vapor from amalgam tooth fillings, and ethyl mercury in the form of thimerosal added as an antiseptic to widely used vaccines. In this article I review human exposure to and the toxicology of each of these three species of mercury. Mechanisms of action are discussed where possible. Key gaps in our current knowledge are identified from the points of view both of risk assessment and of mechanisms of action.

Clarkson, Thomas W

2002-01-01

469

Surface-related mercury in lunar samples.  

PubMed

Lunar samples contain mercury, which may be volatilized at lunar daytime temperatures. Such mercury may constitute part of the tenuous lunar atmosphere. If mercury can escape from the atmosphere by a nonthermal mechanism, an interior reservoir or exterior sources (such as meteorite infall or solar wind, or both) are required to replenish it. Core samples exhibit an increase in surface-related mercury with depth, which suggests that a cold trap exists below the surface. The orientation of rocks on the lunar surface may be inferred by differences in the amounts of surface-related mercury found on exterior and interior samples. PMID:17847244

Reed, G W; Goleb, J A; Jovanovic, S

1971-04-16

470

[Exacerbation of pustular psoriasis in mercury poisoning].  

PubMed

A patient suffering from long-standing pustular psoriasis of the palms was treated for 3 weeks with a mercury-containing drug. Exacerbation into generalized pustular psoriasis developed. Mercury levels in blood and urine were increased. After withdrawal of the mercury preparation, therapy with DMPA (2,3-Dimercapto-1-propane-sulfonic acid), a mercury antidote, was initiated, together with short-term treatment with aromatic retinoids and PUVA. Within a few days mercury levels decreased significantly and the skin lesions practically disappeared. PMID:8002339

Wehner-Caroli, J; Scherwitz, C; Schweinsberg, F; Fierlbeck, G

1994-10-01

471

Electrochemical determination of mercury: A review.  

PubMed

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

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

2013-07-30

472

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

SciTech Connect

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.

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

473

Analytical and numerical models of uranium ignition assisted by hydride formation  

SciTech Connect

Analytical and numerical models of uranium ignition assisted by the oxidation of uranium hydride are described. The models were developed to demonstrate that ignition of large uranium ingots could not occur as a result of possible hydride formation during storage. The thermodynamics-based analytical model predicted an overall 17 C temperature rise of the ingot due to hydride oxidation upon opening of the storage can in air. The numerical model predicted locally higher temperature increases at the surface; the transient temperature increase quickly dissipated. The numerical model was further used to determine conditions for which hydride oxidation does lead to ignition of uranium metal. Room temperature ignition only occurs for high hydride fractions in the nominally oxide reaction product and high specific surface areas of the uranium metal.

Totemeier, T.C.; Hayes, S.L. [Argonne National Lab., Idaho Falls, ID (United States). Engineering Div.

1996-05-01

474

Apparatus for control of mercury  

DOEpatents

A method and apparatus for reducing mercury in industrial gases such as the flue gas produced by the combustion of fossil fuels such as coal adds hydrogen sulfide to the flue gas in or just before a scrubber of the industrial process which contains the wet scrubber. The method and apparatus of the present invention is applicable to installations employing either wet or dry scrubber flue gas desulfurization systems. The present invention uses kraft green liquor as a source for hydrogen sulfide and/or the injection of mineral acids into the green liquor to release vaporous hydrogen sulfide in order to form mercury sulfide solids.

Downs, William (Alliance, OH); Bailey, Ralph T. (Uniontown, OH)

2001-01-01

475

Environmental contamination and risk assessment of mercury from a historic mercury mine located in southwestern China.  

PubMed

A field survey of mercury pollution in environmental media and human hair samples obtained from residents living in the area surrounding the Chatian mercury mine (CMM) of southwestern China was conducted to evaluate the health risks of mercury to local residents. The results showed that mine waste, and tailings in particular, contained high levels of mercury and that the maximum mercury concentration was 88.50 ?g g(-1). Elevated mercury levels were also found in local surface water, paddy soil, and paddy grain, which may cause severe health problems. The mercury concentration of hair samples from the inhabitants of the CMM exceeded 1.0 ?g g(-1), which is the limit recommended by the US EPA. Mercury concentrations in paddy soil were positively correlated with mercury concentrations in paddy roots, stalks, and paddy grains, which suggested that paddy soil was the major source of mercury in paddy plant tissue. The average daily dose (ADD) of mercury for local adults and preschool children via oral exposure reached 0.241 and 0.624 ?g kg(-1) body weight per day, respectively, which is approaching or exceeds the provisional tolerable daily intake. Among the three oral exposure routes, the greatest contributor to the ADD of mercury was the ingestion of rice grain. Open-stacked mine tailings have resulted in heavy mercury contamination in the surrounding soil, and the depth of appreciable soil mercury concentrations exceeded 100 cm. PMID:22722913

Li, Yonghua

2012-06-22

476

Potential energy surfaces for the uranium hydriding reaction  

NASA Astrophysics Data System (ADS)

We have computed the potential energy surfaces for the low-lying electronic states of uranium hydrides, UHn (n=1-3), which are important in the uranium hydriding reactions. We have employed a number of computational methods including the complete active space multiconfiguration self-consistent field followed by multireference relativistic configuration interaction computations with spin-orbit coupling that included up to 6 million configurations. We find that the activation barrier to insert uranium into H2 is reduced substantially by spin-orbit coupling, and the product species UH2 in its A1 spin-orbit ground state is substantially stable over U(5L)+H2 dissociated products. We have found two electronic states for UH to be quite close to each other, and depending on the level of theory the relative ordering of the 6? and 4I states changes, 4I state being the lowest at the highest second-order configuration interaction level. The UH2 species also exhibits a similar feature in that the triplet state is favored at the single-reference second-order Møller-Plesset and coupled cluster levels, while the quintet state is favored at the multireference and density functional theory levels. The UH3 species is extremely floppy, exhibiting an inversion potential surface that has a barrier smaller than its zero-point energy. It is shown that the UH3 species is considerably more ionic than UH2 or UH, and UH3 is responsible for catalyzing the U-hydriding reaction as the highly positive U site in UH3 reacts with H2 spontaneously without an activation barrier. The results of our computations are compared with previous experimental results. The spin-orbit coupling is shown to be more important for energy activation than near the minima.

Balasubramanian, K.; Siekhaus, Wigbert J.; McLean, William

2003-09-01

477

Materials for Hydrogen Storage: From Complex Hydrides to Functionalized Nanostructures  

NASA Astrophysics Data System (ADS)

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.

Das, G. P.

2011-07-01

478

Structure and properties of metal hydrides prepared by mechanical alloying  

SciTech Connect

Our research examines the structure and reversible hydrogen storage capacity of alloys based on the LaNi{sub 5} intermetallic. The alloys are prepared by mechanical alloying (MA), a technique particularly useful when alloying LaNi{sub 5} with low melting point elements such as tin and calcium. In LaNi{sub 5-y}Sn{sub y}, x-ray diffraction and Rietveld analysis show that tin preferentially occupies the Ni(3g) sites in the LaNi{sub 5} structure, and the unit cell volume increases linearly with tin content to a maximum tin solubility of 7.33 atomic percent (LaNi{sub 4.56}Sn{sub 0.44}). The addition of tin to LaNi{sub 5} causes (a) a logarithmic decrease in the plateau pressures for hydrogen absorption and desorption, which is consistent with the corresponding increase in the volume of the LaNi{sub 5} unit cell; (b) a decrease in the hysteresis between the pressures for hydride formation and decomposition, which is in agreement with a recent theoretical model for the effect; and (c) a linear decrease in the hydrogen storage capacity. Effect (c) is explained by a rigid-band model whereby electrons donated by the tin atoms occupy holes in the 3d band of LaNi{sub 5}, which could otherwise be occupied by electrons donated by the hydrogen atoms. Thermodynamic van`t Hoff analysis for these alloys show an increase in hydride formation enthalpy and no change in entropy with increasing tin concentration. LaNi{sub 5} with calcium additions shows enhanced kinetics of hydrogen absorption/desorption. The powder particles prepared by MA have a larger surface area than particles of the same overall size prepared by arc casting. All LaNi{sub 5}-based alloys prepared by MA in an inert environment require no activation for hydrogen absorption and suffer less comminution upon hydriding/dehydriding.

Wasz, M.L.; Schwarz, R.B.

1995-09-01

479

Optical properties of metal-hydride switchable films  

NASA Astrophysics Data System (ADS)

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.

Griessen, Ronald

2001-03-01

480

Dental amalgam, mercury toxicity, and renal autoimmunity.  

PubMed

Chronic exposure to elemental metallic mercury may induce an immunological glomerular disease. Since humans are exposed to mercury vapor (Hg0) from dental amalgam restorations and kidney is an important target organ of mercury vapor and mercury deposition in kidney increases proportionally with the dose, our aim was to test the occurrence of specific antibodies to antiglomerular basement membrane (anti-GBM-IgG) among individuals with adverse effects to mercury from dental amalgam fillings. We selected a group of patients (n=24) with a history of long-term exposure to mercury vapor from mercury-containing amalgam fillings and showing adverse effects that were laboratory confirmed. Enzyme-linked immunosorbent assays (ELISAs) were used to evaluate serum levels of antibodies to anti-GBM-IgG. None of the patients showed evidence of anti-GBM autoimmunity, either in subgroups with strong allergy to mercury or its compounds (i.e., organic mercury) or in those patients who had past thimerosal-containing vaccines coverage (7 of 24). There was no evidence of the presence of circulating anti-GBM antibodies in subjects suffering from adverse events due to long-term exposure to mercury from dental amalgams, even in individuals who presented allergy to mercury. PMID:18540850

Guzzi, Gianpaolo; Fogazzi, Giovanni Battista; Cantù, Mariadele; Minoia, Claudio; Ronchi, Anna; Pigatto, Paolo D; Severi, Gianluca

2008-01-01

481

Preservation of samples for dissolved mercury  

SciTech Connect

Water samples for dissolved mercury require special treatment because of the high chemical mobility and volatility of this element. Widespread use of mercury and its compounds has provided many avenues for contamination of water. Two laboratory tests were done to determine the relative permeabilities of glass and plastic sample bottles to mercury vapor. Plastic containers were confirmed to be quite permeable to airborne mercury, glass containers were virtually impermeable. Methods of preservation include the use of various combinations of acids, oxidants, and complexing agents. The combination of nitric acid and potassium dichromate successfully preserved mercury in a large variety of concentrations and dissolved forms. Because this acid-oxidant preservative acts as a sink for airborne mercury and plastic containers are permeable to mercury vapor, glass bottles are preferred for sample collection. To maintain a healthy work environment and minimize the potential for contamination of water samples, mercury and its compounds are isolated from the atmosphere while in storage. Concurrently, a program to monitor environmental levels of mercury vapor in areas of potential contamination is needed to define the extent of mercury contamination and to assess the effectiveness of mercury clean-up procedures.

Hamlin, S.N. (Geological Survey, Sacramento, CA (United States))

1989-04-01

482

Mercury capture in bench-scale absorbers  

SciTech Connect

This paper gives,a brief overview of research being conducted at Argonne National Laboratory on the capture of mercury by both dry sorbents and wet scrubbers. The emphasis in the research is on development of a better understanding of the key factors that control the capture of mercury. Future work is expected to utilize that information for the development of new or modified process concepts featuring enhanced mercury capture capabilities. The results and conclusions to date from the Argonne -research on dry sorbents can be summarized as follows: lime hydrates, either regular or high-surface-area, are `not effective in removing mercury; mercury removals are enhanced by the addition of activated carbon; mercury removals with activated carbon decrease with increasing temperature, larger particle size, and decreasing mercury concentration in the gas; and chemical pretreatment (e.g., with sulfur or (CaCl{sub 2}) can greatly increase the removal capacity of activated carbon. Preliminary results from the wet scrubbing research include: no removal of elemental mercury is obtained under normal scrubber operating conditions; mercury removal is improved by the addition of packing or production of smaller gas bubbles to increase the gas-liquid contact area; polysulfide solutions do not appear promising for enhancing mercury removal in typical FGC systems; stainless steel packing appears to have beneficial properties for mercury removal and should be investigated further; and other chemical additives may offer greatly enhanced removals.

Livengood, C.D.; Huang, H.S.; Mendelsohn, M.H.; Wu, J.M.

1994-08-01

483

Worldwide trend of atmospheric mercury since 1995  

NASA Astrophysics Data System (ADS)

Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentration have decreased by about 20 to 38% since 1996 as indicated by long term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 yrs is unprecedented among most of atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant emissions over the period. It suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

Slemr, F.; Brunke, E.-G.; Ebinghaus, R.; Kuss, J.

2011-01-01

484

Worldwide trend of atmospheric mercury since 1995  

NASA Astrophysics Data System (ADS)

Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentrations have decreased by about 20 to 38 % since 1996 as indicated by long-term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 years is unusually large among most atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant anthropogenic emissions over this period. This suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Acidification of oceans, climate change, excess nutrient input and pollution may also contribute by their impact on the biogeochemistry of ocean and soils. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

Slemr, F.; Brunke, E.-G.; Ebinghaus, R.; Kuss, J.

2011-05-01

485