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1

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

2

Mercury  

MedlinePLUS

... crystals. Mercury also combines with carbon to make organic mercury compounds. The most common one, methylmercury, is produced mainly by microscopic organisms in the water and soil. More mercury in the environment can increase the amounts of methylmercury that these ...

3

Mercury  

MedlinePLUS

Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

4

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.

5

Mercury  

MedlinePLUS

... Data and Publications Grants and Funding Science and Technology The Mercury Study Report to Congress About Mercury Basic Information Frequent Questions Human Exposure Health Effects Environmental Effects Protecting Yourself Where You Live Releases and ...

6

Mercury  

NASA Astrophysics Data System (ADS)

Mercury has always held the distinction of being the terrestrial planet most unlike the others. On 18 March 2011, after three successful flybys of Mercury, the MESSENGER spacecraft entered orbit around Mercury. Essential to the payload of MESSENGER are three instruments designed to measure the geochemistry of the surface - an x-ray spectrometer, a gamma-ray spectrometer, and a neutron spectrometer. Together, the data returned by these three instruments - coupled with insights about planetary structure gained from tracking the spacecraft, spectral data measured in orbit, and a new and complete view of the geology of the surface - have begun to revolutionize the people's understanding of Mercury. In this chapter, the authors first review the pre-MESSENGER views of Mercury, followed by the first results from the MESSENGER mission. The authors then discuss the implications of these first results in constraining the origin of Mercury, followed by looking forward to future work.

McCoy, T. J.; Nittler, L. R.

7

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

8

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.

9

[Cloud Point extraction for determination of mercury in Chinese herbal medicine by hydride generation atomic fluorescence spectrometry with optimization using Box-Behnken design].  

PubMed

Cloud point extraction (CPE) is proposed as a pre-concentration procedure for the determination of Hg in Chinese herbal medicine samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). Hg2+ was reacted with dithizone to form hydrophobic chelate under the condition of pH. Using Triton X-114, as surfactant, chelate was quantitatively extracted into small volume of the surfactant-rich phase by heating the solution in a water bath for 15 min and centrifuging. Four variables including pH, dithizone concentration, Triton X-114 concentration and equilibrium temperature (T) showed the significant effect on extraction efficiency of total Hg evaluated by single-factor experiment, and Box-Behnken design and response surface method- ology were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum extraction efficiency. The results showed that the binomial was used to fit the response to experimental levels of each variable. ALL linear, quadratic terms of four variables, and interactions between pH and Trion X-114, pH and di- thizone affected the response value(extraction efficiency) significantly at 5% level. The optimum extraction conditions were as follows: pH 5.1, Triton X-114 concentration of 1.16 g x L(-1), dithizone concentration of 4.87 mol x L(-1), and T 58.2 degrees C, the predicted value of fluorescence was 4528.74 under the optimum conditions, and the experimental value had only 2.1% difference with it. Under the conditions, fluorescence was linear to mercury concentration in the range of 1-5 microg x L(-1). The limit of detection obtained was 0.01247 microg x L(-1) with the relative standard deviations (R.S.D.) for six replicate determinations of 1.30%. The proposed method was successfully applied to determination of Hg in morindae Radix, Andrographitis and dried tangerine samples with the recoveries of 95.0%-100.0%. Apparently Box-Behnken design combined with response surface analysis method was considered to be well used for optimization of the cloud point extraction. PMID:25508751

Wang, Mei; Li, Shan; Zhou, Jian-dong; Xu, Ying; Long, Jun-biao; Yang, Bing-yi

2014-08-01

10

[Cloud Point extraction for determination of mercury in Chinese herbal medicine by hydride generation atomic fluorescence spectrometry with optimization using Box-Behnken design].  

PubMed

Cloud point extraction (CPE) is proposed as a pre-concentration procedure for the determination of Hg in Chinese herbal medicine samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). Hg2+ was reacted with dithizone to form hydrophobic chelate under the condition of pH. Using Triton X-114, as surfactant, chelate was quantitatively extracted into small volume of the surfactant-rich phase by heating the solution in a water bath for 15 min and centrifuging. Four variables including pH, dithizone concentration, Triton X-114 concentration and equilibrium temperature (T) showed the significant effect on extraction efficiency of total Hg evaluated by single-factor experiment, and Box-Behnken design and response surface method- ology were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum extraction efficiency. The results showed that the binomial was used to fit the response to experimental levels of each variable. ALL linear, quadratic terms of four variables, and interactions between pH and Trion X-114, pH and di- thizone affected the response value(extraction efficiency) significantly at 5% level. The optimum extraction conditions were as follows: pH 5.1, Triton X-114 concentration of 1.16 g x L(-1), dithizone concentration of 4.87 mol x L(-1), and T 58.2 degrees C, the predicted value of fluorescence was 4528.74 under the optimum conditions, and the experimental value had only 2.1% difference with it. Under the conditions, fluorescence was linear to mercury concentration in the range of 1-5 microg x L(-1). The limit of detection obtained was 0.01247 microg x L(-1) with the relative standard deviations (R.S.D.) for six replicate determinations of 1.30%. The proposed method was successfully applied to determination of Hg in morindae Radix, Andrographitis and dried tangerine samples with the recoveries of 95.0%-100.0%. Apparently Box-Behnken design combined with response surface analysis method was considered to be well used for optimization of the cloud point extraction. PMID:25474972

Wang, Mei; Li, Shan; Zhou, Jian-dong; Xu, Ying; Long, Jun-biao; Yang, Bing-yi

2014-08-01

11

Mercury  

NASA Technical Reports Server (NTRS)

Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

Gault, D. E.; Burns, J. A.; Cassen, P.; Strom, R. G.

1977-01-01

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

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

14

Hydrides of intermetallic compounds  

Microsoft Academic Search

s  Aspects of the progress over the recent years on hydrides of intermetallic compounds are reviewed with emphasis on structure,\\u000a stability, solid-state properties, catalysis, and kinetics. Some new routes to an understanding of hydride phenomenology are\\u000a indicated. Generally speaking hydrides represent but one special aspect of intermetallic compounds. They are, however, unique\\u000a as model systems for questions concerning the stability of

H. Oesterreicher

1981-01-01

15

Spin-orbit configuration interaction study of potential energy curves and transition probabilities of the mercury hydride molecule and tests of relativistic effective core potentials for Hg, Hg + , and Hg2 +  

NASA Astrophysics Data System (ADS)

Ab initio CI calculations have been carried out for the low-energy states of the mercury hydride molecule HgH and its isotopomers. A relativistic effective core potential (RECP) given by Ross et al. [J. Chem. Phys. 93, 6654 (1990)] is employed to describe all but the Hg 5d and 6s valence electrons. Tests for a series of low-lying states of Hg, Hg+, and Hg2+ demonstrate that 0.1 eV accuracy is obtained at the SCF level with a high-quality basis set for this RECP in comparison with all-electron Dirac-Fock results up to 32 eV excitation energy. The DF values are themselves in error by 1-3 eV on the average compared to experiment, but the present CI calculations based on this RECP lead to considerably higher accuracy because of the importance of correlation effects in such determinations. Energy differences (12 cases) between states with the same number of electrons are computed to an accuracy of 0.1-0.2 eV in all cases after the spin-orbit interaction is included. These results compare favorably with those obtained by Häussermann et al. [Mol. Phys. 78, 1211 (1993)] with a ... 5s2 5p6 5d10 6s2 RECP and a corresponding larger AO basis to describe the more tightly bound electrons. Good agreement is found for the spectroscopic constants of the HgH molecule in its lowest four electronic states: X 2?+1/2, A1 2?1/2, A2 2?3/2, and B 2?+1/2 (maximal errors of 1000 cm-1 for Te, 0.03 Å for re and 150 cm-1 for ?e). An RKR curve reported for the A1 state is shown to be in error beyond r=4.0 a0 because of its failure to describe a key avoided crossing with the B state. Radiative lifetimes computed for the A 2? multiplets are both found to agree with values deduced from experiment to within 40%. The calculations find no difference in the HgH and HgD radiative lifetimes for either the A1 or the A2 states, whereas a large distinction in the measured A1 lifetimes of the two isotopomers is observed, thereby supporting the previous experimental conclusion that strong predissociation occurs in the HgH A1 state. Numerous higher-lying electronic states are also studied, with Te values up to 60 000 cm-1, and on this basis it is argued that earlier assignments for the HgH C-X and D-X transitions are incorrect, as previously concluded by Nedelec et al. [Chem. Phys. 134, 137 (1989)].

Alekseyev, Aleksey B.; Liebermann, Heinz-Peter; Buenker, Robert J.; Hirsch, Gerhard

1996-03-01

16

Mercury: Basic Information  

MedlinePLUS

... elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds. Elemental or metallic mercury is a ... elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds. More information Sources of mercury. Mercury ...

17

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

18

Method for preparing porous metal hydride compacts  

DOEpatents

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

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

1981-01-01

19

Method for preparing porous metal hydride compacts  

DOEpatents

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

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

1980-01-21

20

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.

21

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

22

Hydrogenation using hydrides and acid  

DOEpatents

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

Bullock, R. Morris (Wading River, NY)

1990-10-30

23

Lattice dynamics of metal hydrides  

NASA Astrophysics Data System (ADS)

A simple nonstoichiometric model of metal hydrides is proposed and applied to the study of the phonon dispersion curves and composition-dependent Young's moduli of PdHx (Dx) system. The model can readily take into account the temperature and composition dependence of the metal hydride properties including phase changes.

Rafizadeh, Hamid A.

1981-02-01

24

Lattice dynamics of metal hydrides  

Microsoft Academic Search

A simple nonstoichiometric model of metal hydrides is proposed and applied to the study of the phonon dispersion curves and composition-dependent Young's moduli of PdHx (Dx) system. The model can readily take into account the temperature and composition dependence of the metal hydride properties including phase changes.

Hamid A. Rafizadeh

1981-01-01

25

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

26

[Mercury poisoning].  

PubMed

Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication. PMID:20579784

Bensefa-Colas, L; Andujar, P; Descatha, A

2011-07-01

27

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.

28

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

29

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

30

Complex Hydrides for Hydrogen Storage  

SciTech Connect

This report describes research into the use of complex hydrides for hydrogen storage. The synthesis of a number of alanates, (AIH4) compounds, was investigated. Both wet chemical and mechano-chemical methods were studied.

Slattery, Darlene; Hampton, Michael

2003-03-10

31

Got Mercury?  

NASA Technical Reports Server (NTRS)

Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/cu m in the total spacecraft atmosphere for exposures lasting 30 days or less or 0.01 mg/cu m mercury vapor for exposures lasting more than 30 days. We also encourage the use of alternative devices that do not contain mercury.

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

2009-01-01

32

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 powered 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.

Maienschein, Jon L. (Oakland, CA); Barry, Patrick E. (Pleasant Hill, CA)

1991-01-01

33

Hydrogen recovery with metal hydrides  

SciTech Connect

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

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

1982-03-01

34

Fundamental experiments on hydride reorientation in zircaloy  

NASA Astrophysics Data System (ADS)

In the current study, an in-situ X-ray diffraction technique using synchrotron radiation was used to follow directly the kinetics of hydride dissolution and precipitation during thermomechanical cycles. This technique was combined with conventional microscopy (optical, SEM and TEM) to gain an overall understanding of the process of hydride reorientation. Thus this part of the study emphasized the time-dependent nature of the process, studying large volume of hydrides in the material. In addition, a micro-diffraction technique was also used to study the spatial distribution of hydrides near stress concentrations. This part of the study emphasized the spatial variation of hydride characteristics such as strain and morphology. Hydrided samples in the shape of tensile dog-bones were used in the time-dependent part of the study. Compact tension specimens were used during the spatial dependence part of the study. The hydride elastic strains from peak shift and size and strain broadening were studied as a function of time for precipitating hydrides. The hydrides precipitate in a very compressed state of stress, as measured by the shift in lattice spacing. As precipitation proceeds the average shift decreases, indicating average stress is reduced, likely due to plastic deformation and morphology changes. When nucleation ends the hydrides follow the zirconium matrix thermal contraction. When stress is applied below the threshold stress for reorientation, hydrides first nucleate in a very compressed state similar to that of unstressed hydrides. After reducing the average strain similarly to unstressed hydrides, the average hydride strain reaches a constant value during cool-down to room temperature. This could be due to a greater ease of deforming the matrix due to the applied far-field strain which would compensate for the strains due to thermal contraction. Finally when hydrides reorient, the average hydride strains become tensile during the first precipitation regime and remain constant in the tensile direction during the second precipitation regime. This could be due to the fact that the face of reoriented hydride platelet is in compression once these platelets have grown to a sufficient size. The second goal of this study was to perform a spatially resolved study of the effect of a stress concentration such as a notch or a crack on hydride reorientation. Using SEM and image analysis, it was found that a sharp crack induces a different hydride microstructure than a blunt notch. In the case of sharp crack, hydrides are more localized and align more with the defect than for blunt notches. The hydride connectivity also increases close to a stress concentration which will assist in crack propagation during DHC. Using TEM, the microstructure of hydrides grown near crack tips were observed to be similar to that of circumferential hydrides grown in the bulk. The orientation relationship studied with SEM and micro-X-ray diffraction was found to be in most cases ?(111)// ?(0002) for hydrides grown both near and far from stress concentrations. Using the same micro-X-ray diffraction technique local hydride and matrix elastic strains were measured and observed to vary significantly from grain to grain. It was however observed that hydrides grown close to the stress concentration are in tension in the face of the platelet, similar to reoriented hydrides, while those grown far from the stress concentration are in tension, similar to circumferential hydrides. The orders of magnitude of the measured strains in the hydrides and the zirconium matrix compared well to those predicted by finite element models. This study shows that it is possible to study hydride dissolution and precipitation in-situ using time-dependent techniques. It was found that the precipitation temperature is lowered by hydride reorientation. The evolution of hydride strains during precipitation was found to be different for unstressed, stressed and reoriented hydrides. The reoriented hydride fraction and connectivity increase with number of cycles which could lead to mor

Colas, Kimberly B.

35

Mercury and Your Health  

MedlinePLUS

... the Risk of Exposure to Mercury Learn About Mercury What is Mercury? What is Metallic Mercury? Toxicological ... PDF - 3.6MB) En Español (PDF - 1.8MB) Mercury Resources CDC’s Fourth National Report on Human Exposure ...

36

Bulk Hydrides and Delayed Hydride Cracking in Zirconium Alloys  

NASA Astrophysics Data System (ADS)

Zirconium alloys are susceptible to engineering problems associated with the uptake of hydrogen throughout their design lifetime in nuclear reactors. Understanding of hydrogen embrittlement associated with the precipitation of brittle hydride phases and a sub-critical crack growth mechanism known as Delayed Hydride Cracking (DHC) is required to provide the engineering justifications for safe reactor operation. The nature of bulk zirconium hydrides at low concentrations (< 100 wt. ppm) is subject to several contradictory descriptions in the literature associated with the stability and metastability of gamma-phase zirconium hydride. Due to the differing volume expansions (12-17%) and crystallography between gamma and delta hydride phases, it is suggested that the matrix yield strength may have an effect on the phase stability. The present work indicated that although yield strength can shift the phase stability, other factors such as microstructure and phase distribution can be as or more important. This suggests that small material differences are the reason for the literature discrepancies. DHC is characterised by the repeated precipitation, growth, fracture of brittle hydride phases and subsequent crack arrest in the ductile metal. DHC growth is associated primarily the ability of hydrogen to diffuse under a stress induced chemical potential towards a stress raiser. Knowledge of the factors controlling DHC are paramount in being able to appropriately describe DHC for engineering purposes. Most studies characterise DHC upon cooling to the test temperature. DHC upon heating has not been extensively studied and the mechanism by which it occurs is somewhat controversial in the literature. This work shows that previous thermo-mechanical processing of hydrided zirconium can have a significant effect on the dissolution behaviour of the bulk hydride upon heating. DHC tests with gamma-quenched, furnace cooled-delta and reoriented bulk hydrides upon heating and DHC upon cooling suggest that the amount of hydrogen in solution is the primary factor controlling the occurrence of DHC and consistent with the postulation that the stress induced chemical potential is the driving force for DHC.

Tulk, Eric F.

37

A new route to metal hydrides  

Microsoft Academic Search

Aqueous borohydride is shown to be an effective reagent for hydriding metals and intermetallics. It is the hydriding equivalent of 20-30 atm of H[sub 2]. The reaction is a convenient way to screen materials for hydride formation and possible utility in applications such as nickel-metal hydride batteries. The reaction is also a convenient alternative to decrepitation for the production of

D. W. Murphy; S. M. Zahurak; B. Vyas; M. Thomas; M. E. Badding; W. C. Fang

1993-01-01

38

Vanadium hydride deuterium-tritium generator  

DOEpatents

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

Christensen, Leslie D. (Livermore, CA)

1982-01-01

39

Hydrogen, lithium, and lithium hydride production  

DOEpatents

A method of producing high purity lithium metal is provided, where gaseous-phase lithium metal is extracted from lithium hydride and condensed to form solid high purity lithium metal. The high purity lithium metal may be hydrided to provide high purity lithium hydride.

Brown, Sam W; Spencer, Larry S; Phillips, Michael R; Powell, G. Louis; Campbell, Peggy J

2014-03-25

40

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

41

Mercury Thermometer Replacement Alternatives Thermometer Description Non-Mercury Non-Mercury Non-Mercury  

E-print Network

Mercury Thermometer Replacement Alternatives Length Thermometer Description Non-Mercury Non-Mercury Non-Mercury Range / Division VWR-Enviro-Safe® Fisherbrand® Brooklyn Thermometer Company Inc. Total/A #12;Mercury Thermometer Replacement Alternatives Length Thermometer Description Non-Mercury Non-Mercury

42

Mercury Bubbles  

Microsoft Academic Search

I HAVE on several occasions noticed the beautiful bubbles described by Mr. Wright and Sir William Crookes (pp. 8 and 37). On each occasion I was purifying mercury in the following way. I half filled a rather large Woulffe's bottle with mercury and poured on to it weak nitric acid. Then, in order to keep, the whole in a state

A. T. Hare

1908-01-01

43

BRIEF COMMUNICATIONS: Feasibility of developing a mercury hydride molecular laser  

NASA Astrophysics Data System (ADS)

The formation and deexcitation of the A2?1/2 and X2?1/2 states of the HgH molecule in a dense Hg-H2-He (N2, 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 A2?1/2 (? = 0,1) and A2?3/2 (? = 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

Microstructure of surface cerium hydride growth sites  

SciTech Connect

Samples of cerium were exposed to hydrogen under controlled conditions causing cerium hydride sites to nucleate and grow on the surface. The hydriding rate was measured in situ, and the hydrides were characterised using secondary ion mass spectrometry, scanning electron microscopy, and optical microscopy. The results show that the hydriding rate proceeded more quickly than earlier studies. Characterisation confirmed that the hydrogen is confined to the sites. The morphology of the hydrides was confirmed to be oblate, and stressed material was observed surrounding the hydride, in a number of cases lathlike features were observed surrounding the hydride sites laterally with cracking in the surface oxide above them. It is proposed that during growth the increased lattice parameter of the CeH{sub 2} induces a lateral compressive stress around the hydride, which relieves by the ca. 16% volume collapse of the ?-Ce to ?-Ce pressure induced phase transition. Cracking of the surface oxide above the laths reduces the diffusion barrier to hydrogen reaching the metal/oxide interface surrounding the hydride site and contributes to the anisotropic growth of the hydrides.

Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire, RG7 4PR, United Kingdom and The School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Knowles, John; Montgomery, Neil [Atomic Weapons Establishment, Aldermaston, Berkshire, RG7 4PR (United Kingdom); Preuss, Michael [The School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom)

2014-05-15

45

Got Mercury?  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

46

Rechargeable metal hydrides for spacecraft application  

NASA Technical Reports Server (NTRS)

Storing hydrogen on board the Space Station presents both safety and logistics problems. Conventional storage using pressurized bottles requires large masses, pressures, and volumes to handle the hydrogen to be used in experiments in the U.S. Laboratory Module and residual hydrogen generated by the ECLSS. Rechargeable metal hydrides may be competitive with conventional storage techniques. The basic theory of hydride behavior is presented and the engineering properties of LaNi5 are discussed to gain a clear understanding of the potential of metal hydrides for handling spacecraft hydrogen resources. Applications to Space Station and the safety of metal hydrides are presented and compared to conventional hydride storage. This comparison indicates that metal hydrides may be safer and require lower pressures, less volume, and less mass to store an equivalent mass of hydrogen.

Perry, J. L.

1988-01-01

47

Ground state of positronium hydride  

SciTech Connect

The ground bound state in the positronium hydride molecule (HPs) is determined from extensive variational four-body calculations with the James-Coolidge four-body variational expansion in the relative coordinates r{sub 12},r{sub 13},r{sub 23},r{sub 14},r{sub 24}, and r{sub 34}. For the positronium hydride with the infinitely heavy nucleus ({sup {infinity}}HPs) the total energy found, E={minus}0.7891369 a.u., is one of the lowest variational values published to date. A number of bound-state properties have been calculated also, including the {delta}-function expectation values, two-body cusps, and the two-photon annihilation rate. {copyright} {ital 1997} {ital The American Physical Society}

Frolov, A.M.; Smith, V.H. , Jr. [Department of Chemistry, Queens University, Kingston, Ontario, K7L3N6 (CANADA)] [Department of Chemistry, Queens University, Kingston, Ontario, K7L3N6 (CANADA)

1997-09-01

48

Catalytic metal hydride space heater  

SciTech Connect

This patent describes an apparatus for heating which consists of: a fuel storage means and wall means forming a combustion area wherein the improvement comprises: (a) the fuel storage means comprising a metal hydride fuel; (b) the wall means forming the combustion area containing a catalyst thereon; (c) the wall means forming the combustion area being in direct proximity to the metal hydride fuel storage means; (d) means for controllable supplying air to the combustion area; (e) the fuel storage means including a semipermeable membrane through which hydrogen may pass; (f) means for conveying hydrogen from the semipermeable membrane to the combustion area; and (g) means for discharging products from the combustion area to an area to be heated.

Kesten, A.S.

1986-09-30

49

Vanadium hydride deuterium-tritium generator  

DOEpatents

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

Christensen, L.D.

1980-03-13

50

Inhibited solid propellant composition containing beryllium hydride  

NASA Technical Reports Server (NTRS)

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-terminated polybutadiene. It was found that a small amount of lecithin inhibits the reaction of beryllium hydride with the acid groups in carboxy terminated polybutadiene.

Thompson, W. W. (inventor)

1978-01-01

51

Use of reversible hydrides for hydrogen storage  

NASA Technical Reports Server (NTRS)

The addition of metals or alloys whose hydrides have a high dissociation pressure allows a considerable increase in the hydrogenation rate of magnesium. The influence of temperature and hydrogen pressure on the reaction rate were studied. Results concerning the hydriding of magnesium rich alloys such as Mg2Ca, La2Mg17 and CeMg12 are presented. The hydriding mechanism of La2Mg17 and CeMg12 alloys is given.

Darriet, B.; Pezat, M.; Hagenmuller, P.

1980-01-01

52

A possible new meteor shower - ? Hydrids  

NASA Astrophysics Data System (ADS)

The radiant analysis that included orbits from the Croatian Meteor Network Catalogues of Orbits 2007 to 2010 plus the orbits from the SonotaCo catalogues for 2007 to 2011 revealed a possible new Hydrid stream with radiant running parallel to, but distinct from, the sigma Hydrids. The stream got a temporary IAU designation 529 EHY and the name ? Hydrids. We present here the results of our analysis of the new stream.

Šegon, Damir; Andrei?, Željko; Korlevi?, Korado; Novoselnik, Filip; Vida, Denis; Skoki?, Ivica

2013-10-01

53

Complex hydrides for hydrogen storage  

DOEpatents

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

Zidan, Ragaiy

2006-08-22

54

Mercury Contamination  

PubMed Central

IN BRIEF A residential elemental mercury contamination incident in Rhode Island resulted in the evacuation of an entire apartment complex. To develop recommendations for improved response, all response-related documents were examined; personnel involved in the response were interviewed; policies and procedures were reviewed; and environmental monitoring data were compiled from specific phases of the response for analysis of effect. A significant challenge of responding to residential elemental mercury contamination lies in communicating risk to residents affected py a HazMat spill. An ongoing, open and honest dialogue is emphasized where concerns of the public are heard and addressed, particularly when establishing and/or modifying policies and procedures for responding to residential elemental mercury contamination. PMID:23436951

Thompson, Marcella R.

2013-01-01

55

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.

56

Direct synthesis of catalyzed hydride compounds  

DOEpatents

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

Gross, Karl J.; Majzoub, Eric

2004-09-21

57

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

58

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

59

Mercury exanthem.  

PubMed

We experienced 15 patients with generalized rash, mostly appearing a day or two after breaking a clinical thermometer or during dental treatment. Similar skin manifestations were revealed, suggestive at first glance of mercury exanthem, i.e. diffuse symmetrical erythema predominantly on major fluxural areas. An inverted triangular or V-shaped erythema on both upper antero-medial thighs was a common feature. Severe cases had miliary pustules and/or purpura on erythematous skin. Pruritus or burning sensation was relatively mild. Pyrexia or malaise was a complaint of more than half the patients. Most of the patients had a previous history of contact dermatitis to Mercurochrome, and by patch-testing were found to have contact allergy to several mercurials, especially inorganic ones. Until recently, Mercurochrome had been most widely used as a topical disinfectant in Japan. This seems to be a possible cause of the high incidence of contact allergy to mercurials in this country. From our findings we feel that our patients had developed systemic contact dermatitis due to inhalation of mercury vapor. PMID:6194931

Nakayama, H; Niki, F; Shono, M; Hada, S

1983-09-01

60

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.

2010-09-16

61

Activated aluminum hydride hydrogen storage compositions and uses thereof  

DOEpatents

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

62

Revealing Mercury  

NASA Astrophysics Data System (ADS)

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, launched in August 2004. En route to insertion into orbit about Mercury in 2011, MESSENGER flies by Mercury three times. The first and second of these encounters were accomplished in January and October of 2008. These flybys viewed portions of Mercury's surface that were not observed by Mariner 10 during its reconnaissance of somewhat less than half of the planet in 1974-1975. All MESSENGER instruments operated during each flyby and returned a wealth of new data. Many of the new observations were focused on the planet's geology, including monochrome imaging at resolutions as high as 100 m/pixel, multispectral imaging in 11 filters at resolutions as high as 500 m/pixel, laser altimetry tracks extending over several thousands of kilometers, and high-resolution spectral measurements of several types of terrain. Here we present an overview of the first inferences on the global geology of Mercury from the MESSENGER observations. Whereas evidence for volcanism was equivocal from Mariner 10 data, the new MESSENGER images and altimetry provide compelling evidence that volcanism was widespread and protracted on Mercury. Color imaging reveals three common spectral units on the surface: a higher-reflectance, relatively red material occurring as a distinct class of smooth plains, typically with distinct embayment relationships interpreted to indicate volcanic emplacement; a lower-reflectance, relatively blue material typically excavated by impact craters and therefore inferred to be more common at depth; and a spectrally intermediate terrain that constitutes much of the uppermost crust. Three more minor spectral units are also seen: fresh crater ejecta, reddish material associated with rimless depressions interpreted to be volcanic centers, and high-reflectance deposits seen in some crater floors. Preliminary measurements of crater size-frequency distribution suggest that smooth plains on Mercury's surface range in age from the end of the period of heavy impact bombardment to as young as perhaps 1 billion years; these ongoing measurements are helping to elucidate the volcanic history of the planet. Mercury's global tectonic history is also revealed by the MESSENGER image and laser altimeter data. Significant evidence for global contraction was seen in Mariner 10 images in the form of widespread lobate scarps. The MESSENGER images show that contractional features are the dominant tectonic landform globally, and the inferred average contractional strain is at least one third greater than previously inferred from Mariner 10 observations. Only three exceptions to the dominance of contractional deformation have been found to date: extensional troughs that include prominent basin-radial systems documented in two basins, the Pantheon Fossae within the 1500-km-diameter Caloris basin and a similar set of features within a newly-imaged 700-km-diameter basin, and a circumferential trough system within the smaller, younger Raditladi basin. That these extensional tectonic features are rare on Mercury, and that they are not seen within basins elsewhere in the Solar System, pose important constraints on the thermal and mechanical evolution of Mercury's interior.

Prockter, L. M.; Solomon, S. C.; Head, J. W.; Watters, T. R.; Murchie, S. L.; Robinson, M. S.; Chapman, C. R.; McNutt, R. L.

2009-04-01

63

MERCURY IN TREE RINGS  

EPA Science Inventory

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

64

Hydrogen-storing hydride complexes  

DOEpatents

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

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

2012-04-10

65

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

66

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

67

Encapsulated Metal Hydride for Hydrogen Separation  

E-print Network

hydrogen separation from gas mixtures containing methane and carbon monoxide. But absorption kinetics;Accomplishments/Progress (1) · Milestones: 1. Begin hydrogen absorption test from mixtures containing nitrogenEncapsulated Metal Hydride for Hydrogen Separation (Formerly Separation Membrane Development) DOE

68

Disposal of tritium-exposed metal hydrides  

SciTech Connect

A plan has been established for disposal of tritium-exposed metal hydrides used in Savannah River Site (SRS) tritium production or Materials Test Facility (MTF) R D operations. The recommended plan assumes that the first tritium-exposed metal hydrides will be disposed of after startup of the Solid Waste Disposal Facility (SWDF) Expansion Project in 1992, and thus the plan is consistent with the new disposal requiremkents that will be in effect for the SWDF Expansion Project. Process beds containing tritium-exposed metal hydride powder will be disposed of without removal of the powder from the bed; however, disposal of tritium-exposed metal hydride powder that has been removed from its process vessel is also addressed.

Nobile, A.; Motyka, T.

1991-01-01

69

Disposal of tritium-exposed metal hydrides  

SciTech Connect

A plan has been established for disposal of tritium-exposed metal hydrides used in Savannah River Site (SRS) tritium production or Materials Test Facility (MTF) R&D operations. The recommended plan assumes that the first tritium-exposed metal hydrides will be disposed of after startup of the Solid Waste Disposal Facility (SWDF) Expansion Project in 1992, and thus the plan is consistent with the new disposal requiremkents that will be in effect for the SWDF Expansion Project. Process beds containing tritium-exposed metal hydride powder will be disposed of without removal of the powder from the bed; however, disposal of tritium-exposed metal hydride powder that has been removed from its process vessel is also addressed.

Nobile, A.; Motyka, T.

1991-12-31

70

Mercury's Magnetosphere  

NASA Technical Reports Server (NTRS)

Among the major discoveries made by the Mariner 10 mission to the inner planets was the existence of an intrinsic magnetic field at Mercury with a dipole moment of approx. 300 nT R(sup 3, sub M). This magnetic field is sufficient to stand off the solar wind at an altitude of about 1 R(sub M) (i.e. approx. 2439 km). Hence, Mercury possesses a 'magnetosphere' from which the so]ar wind plasma is largely excluded and within which the motion of charged particles is controlled by the planetary magnetic field. Despite its small size relative to the magnetospheres of the other planets, a Mercury orbiter mission is a high priority for the space physics community. The primary reason for this great interest is that Mercury unlike all the other planets visited thus far, lacks a significant atmosphere; only a vestigial exosphere is present. This results in a unique situation where the magnetosphere interacts directly with the outer layer of the planetary crust (i.e. the regolith). At all of the other planets the topmost regions of their atmospheres become ionized by solar radiation to form ionospheres. These planetary ionospheres then couple to electrodynamically to their magnetospheres or, in the case of the weakly magnetized Venus and Mars, directly to the solar wind. This magnetosphere-ionosphere coupling is mediated largely through field-aligned currents (FACs) flowing along the magnetic field lines linking the magnetosphere and the high-latitude ionosphere. Mercury is unique in that it is expected that FACS will be very short lived due to the low electrical conductivity of the regolith. Furthermore, at the earth it has been shown that the outflow of neutral atmospheric species to great altitudes is an important source of magnetospheric plasma (following ionization) whose composition may influence subsequent magnetotail dynamics. However, the dominant source of plasma for most of the terrestrial magnetosphere is the 'leakage'of solar wind across the magnetopause and more direct entry through the northern and southern cusps. Although Mariner 10 did not return plasma composition measurements, the Hermean magnetosphere should be ideal for measuring the manner and rate of solar wind plasma entry due to the lack of strong internal atmospheric sources. Finally, the solar wind conditions experienced by Mercury as it orbits the Sun at 0.31 to 0.47 AU are quite different from those typically encountered by the Earth. This may allow for new understanding of the external factors affecting the transfer of mass, momentum and energy from the solar wind to planetary magnetospheres. This article provides a brief overview of what is now known about Mercury's magnetosphere and why it is a priority target for future planetary missions.

Slavin, J. A.

1999-01-01

71

A classical but new kinetic equation for hydride transfer reactions.  

PubMed

A classical but new kinetic equation to estimate activation energies of various hydride transfer reactions was developed according to transition state theory using the Morse-type free energy curves of hydride donors to release a hydride anion and hydride acceptors to capture a hydride anion and by which the activation energies of 187 typical hydride self-exchange reactions and more than thirty thousand hydride cross transfer reactions in acetonitrile were safely estimated in this work. Since the development of the kinetic equation is only on the basis of the related chemical bond changes of the hydride transfer reactants, the kinetic equation should be also suitable for proton transfer reactions, hydrogen atom transfer reactions and all the other chemical reactions involved with breaking and formation of chemical bonds. One of the most important contributions of this work is to have achieved the perfect unity of the kinetic equation and thermodynamic equation for hydride transfer reactions. PMID:23917398

Zhu, Xiao-Qing; Deng, Fei-Huang; Yang, Jin-Dong; Li, Xiu-Tao; Chen, Qiang; Lei, Nan-Ping; Meng, Fan-Kun; Zhao, Xiao-Peng; Han, Su-Hui; Hao, Er-Jun; Mu, Yuan-Yuan

2013-09-28

72

Heat transfer enhancement in metal hydride systems  

NASA Astrophysics Data System (ADS)

An attempt has been made to enhance the heat transfer of hydrogen storage metal hydride systems by the addition of small fraction of high conductivity materials in various configurations. Results indicate that the form of the enhancement material rather than its composition is the more critical factor. The addition of over 6% aluminum foam enhances the effective thermal conductivity of a hydride bed by a factor of 2.6.

Rosso, M. J., Jr.; Strickland, G.

73

Mercury Contact Micromechanical Relays  

Microsoft Academic Search

This paper presents the use of mercury microdrop (microns in diameter) as a contact in micromechanical relays in microelectromechanical systems (MEMS). Mercury microdrops can be deposited on lithographica lly defined sites on surface by the technique and apparatus developed in UCLA Micromanufacturing Laboratory. Three different micro mercury relays are described. First device has a mercury microdrop in a channel, which

Joonwon Kim; Jonathan Simon; Scott Saffer

74

To Mercury dynamics  

Microsoft Academic Search

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

Yu. V. Barkin; J. M. Ferrandiz

2004-01-01

75

Mercury contamination extraction  

SciTech Connect

Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

Fuhrmann, Mark (Silver Spring, MD); Heiser, John (Bayport, NY); Kalb, Paul (Wading River, NY)

2009-09-15

76

Mercury in the Environment  

Microsoft Academic Search

The only mercury compounds presenting significant danger to humans are alkyl mercury compounds, of which methylmercury is the most toxic. Studies have shown that both inorganic and elemental forms of mercury can be methylated in lake and river sediments to form these dangerous compounds. The principal sources of mercury in the environment are discussed. For the US and Canada, they

Aoronson

1971-01-01

77

MERCURY RESEARCH STRATEGY.  

EPA Science Inventory

The USEPA's ORD is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001-2005 time frame. ORD will use it to prepare a multi-year mercury research implementation plan in 2001. The Mercury R...

78

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. PMID:21120080

Rustagi, Neeti; Singh, Ritesh

2010-01-01

79

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

E-print Network

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

Boyer, Edmond

80

[Determination of trace mercury species in water and soil samples with atomic fluorescence spectrometry].  

PubMed

With hydride generation-cold atomic fluorescence spectrometry (HG-AFS), the method of determining trace mercury species in water and soil samples in Jimei, Xiamen city, China was established. The content of inorganic mercury in water was measured by sample direct injection, while the total mercury was measured after digestion with the reagents of KBrO3-KBr. The soil samples were digested with microwave for total mercury measurement. Sequential extraction procedure was carried out for determining different mercuric species in soil samples. The results indicated that the mercury concentration of wastewater from chemical laboratory exceeded the limit of the integrated wastewater discharge standard of China (GB 8978-1996). It is one of the serious pollution sources of mercury in environment. The mercury contents from soil samples including the sideward soil of highway, the sea sediment and the garden soil were under the limits of relative national standards of China. However, attention should be paid to the accumulation of mercury in garden soil due to the artificial pollution. Meanwhile, the average recoveries for water and soil samples tested with adding standards were 93.7% and 93.8%, respectively. Meanwhile, the detection limits estimated with 3-fold standard deviation were 0.000 8 microg x L(-1) for water and 0.072 3 microg x kg(-1) for soil, respectively. The results indicated that the established method, with the merits of high sensitivity and precision, was suitable for the measurement of trace mercury species in environmental samples. PMID:18260432

Huang, Zhi-Yong; Huang, Zhi-Tao; Zhang, Qiang; Zhuang, Zhi-Xia

2007-11-01

81

76 FR 13851 - National Emission Standards for Hazardous Air Pollutants: Mercury Emissions From Mercury Cell...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants; Proposed Rule Federal...Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants AGENCY: Environmental...NESHAP) for mercury emissions from mercury cell chlor-alkali plants (Mercury Cell...

2011-03-14

82

Thermal hydraulic analysis of hydride fuels in BWR's  

E-print Network

This thesis contributes to the hydride nuclear fuel project being completed by UC Berkeley and MIT to assess the possible benefits of using hydride fuel in light water nuclear reactors (LWR's). More specifically, this ...

Creighton, John Everett

2005-01-01

83

Optimization of hydride fueled pressurized water reactor cores  

E-print Network

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

Shuffler, Carter Alexander

2004-01-01

84

High H? ionic conductivity in barium hydride  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

85

High H? ionic conductivity in barium hydride.  

PubMed

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

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

2015-01-01

86

The IEA\\/DOE\\/SNL on-line hydride databases  

Microsoft Academic Search

.   A series of comprehensive hydride databases have been constructed and made freely available on the Internet (URL http:\\/\\/hydpark.ca.sandia.gov).\\u000a They include extensive listings of alloys reported to hydride, detailed engineering properties on selected hydrogen-storage\\u000a elements and alloys and a hydride-applications database. These databases and an associated reference database are described,\\u000a along with other hydride information available on the web site.

G. Sandrock; G. Thomas

2001-01-01

87

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.

D.P. Krabbenhoft

88

Can hydridic-to-protonic hydrogen bonds catalyze hydride transfers in biological systems?  

PubMed

Catalysis of hydride transfer by hydridic-to-protonic hydrogen (HHH) bonding in ?-hydroxy carbonyl isomerization reactions was examined computationally in the lithium salts of 7-substituted endo-3-hydroxybicyclo[2.2.1]hept-5-en-2-ones. The barrier for intramolecular hydride transfer in the parent system was calculated to be 17.2 kcal/mol. Traditional proton donors, such as OH and NH(3)(+), stabilized the metal cation-bridged transition state by 1.4 and 3.3 kcal/mol, respectively. Moreover, among the conformers of the OH systems, the one in which the proton donor is able to interact with the migrating hydride (H(m)) has an activation barrier lower by 1.3 and 1.7 kcal/mol than the other possible OH conformers. By contrast, the presence of an electronegative group such as F, which disfavors the migration electronically by opposing development of hydridic charge, destabilizes the hydride migration by 1.5 kcal/mol relative to the epimeric exo system. In both ground and transition states the H(m)···H distance decreased with increasing acidity of the proton donor, reaching a minimum of 1.58 Å at the transition state for NH(3)(+). Both Mulliken and NPA charges show enhancement of negative character of the migrating hydride in the cases in which HHH bonding is possible. PMID:21141894

Marincean, Simona; Jackson, James E

2010-12-30

89

Gold Hydride Complexes DOI: 10.1002/anie.200803842  

E-print Network

Gold Hydride Complexes DOI: 10.1002/anie.200803842 Reactions of a Stable Monomeric Gold(I) Hydride Complex** Emily Y. Tsui,* Peter Müller, and Joseph P. Sadighi Gold hydride complexes have been postulated as intermediates in a number of homogeneous gold- catalyzed reactions,[1] but relatively little is known about

Müller, Peter

90

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...exceeding 25 MPa. Metal hydride storage systems must be designed...H” mark must be used for hydrogen bearing gases or other...

2012-10-01

91

49 CFR 173.311 - Metal hydride storage systems.  

Code of Federal Regulations, 2013 CFR

...173.311 Metal hydride storage systems. The following...transportable UN Metal hydride storage systems (UN3468) with...exceeding 25 MPa. Metal hydride storage systems must be designed...H” mark must be used for hydrogen bearing gases or other...

2013-10-01

92

49 CFR 173.311 - Metal hydride storage systems.  

Code of Federal Regulations, 2011 CFR

...173.311 Metal hydride storage systems. The following...transportable UN Metal hydride storage systems (UN3468) with...exceeding 25 MPa. Metal hydride storage systems must be designed...H” mark must be used for hydrogen bearing gases or other...

2011-10-01

93

49 CFR 173.311 - Metal hydride storage systems.  

Code of Federal Regulations, 2014 CFR

...173.311 Metal hydride storage systems. The following...transportable UN Metal hydride storage systems (UN3468) with...exceeding 25 MPa. Metal hydride storage systems must be designed...H” mark must be used for hydrogen bearing gases or other...

2014-10-01

94

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

2012-11-01

95

New Jersey mercury regulations  

SciTech Connect

Mercury, or quicksilver, and its major ore cinnabar (HgS) have been known for thousands of years. Health effects from mercury such as dementia were known as early as the late 19th century ({open_quotes}mad as a hatter{close_quotes}). In the 1960`s and 1970`s, reported levels of mercury in tuna reawakened public awareness of mercury pollution. In the 1970`s, major epidemics of acute mercury poisoning were reported in Japan and Iraq. These incidents highlighted the extreme health risks, such as kidney damage, birth defects, and death, associated with severe mercury poisoning. Fetuses and young children are particularly vulnerable since mercury poisoning can damage growing neural tissues. Recently, the perception of mercury as a dangerous pollutant has been on the rise. Advisories warning the public to avoid or reduce the consumption of freshwater fish caught in specific waterbodies due to mercury contamination have been issued in numerous states. The discovery of mercury in {open_quotes}pristine{close_quotes} lakes in the United States, Canada, and Scandinavia, remote from industry and any known mercury sources, has focused attention on atmospheric emissions of mercury as potential significant sources of mercury.

Elias, D.F.; Corbin, W.E. [RTP Environmental Associates, Inc., Green Brook, NJ (United States)

1996-12-31

96

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

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

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

97

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 ...

Ms. Simpson

2009-10-21

98

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

99

MERCURY IN THE ENVIRONMENT  

EPA Science Inventory

Mercury is released from a variety of sources and exhibits a complicated chemistry. According to the Mercury Study Report to Congress, mercury fluxes and budgets in water, soil, and other media have increased by a factor of two to five over pre-industrial levels. The primary expo...

100

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...

101

Mercury Surveillance Program  

NASA Technical Reports Server (NTRS)

Background on mercury exposure is presented including forms, sources, permissible exposure limits, and physiological effects. The purpose of the Mercury Surveillance Program at LeRC is outlined, and the specifics of the Medical Surveillance Program for Mercury Exposure at LeRC are discussed.

1993-01-01

102

Effect of yttrium on nucleation and growth of zirconium hydrides  

NASA Astrophysics Data System (ADS)

Addition of yttrium in zirconium causes precipitates of yttrium, which form two types of particles and are oxidized upon heat treatment. One type of particles with sub-micrometer scale sizes has a low population, whereas the other with nano scale sizes has a high population and cluster distribution. Owing to strong affinity of yttrium to hydrogen, the nanoparticles, mostly within the grains of the Zr-Y alloy, attract nucleation of hydrides at the clusters of the nanoparticles and cause preferential distribution of intragranular hydrides. In comparison with that of Zr, additional nanoparticles in the Zr-Y alloy impede further growth of hydride precipitates during hydriding. It is deduced that the impediment of growing hydride precipitates by the nanoparticles is developed during an auto-catalytic nucleation process, which leads to formation of thin and intragranular hydrides, favorable to mitigation of hydride embrittlement.

Li, Changji; Xiong, Liangyin; Wu, Erdong; Liu, Shi

2015-02-01

103

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

104

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

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

2009-05-05

106

High-Suction Hydride Sorption Pump  

NASA Technical Reports Server (NTRS)

Improved design provides high pumping speed at low pressure. Hydride-forming powder retained in thin layer in contact with inner surface of stainless-steel tube. Configuration provides large surface area and short path for efficient transfer of heat and small resistance to flow.

Bard, Steven; Jones, Jack A.; Bowman, Robert C., Jr.; Dowling, Robert S.

1993-01-01

107

Ductility Evaluation of As-Hydrided and Hydride Reoriented Zircaloy-4 Cladding under Simulated Dry-Storage Condition  

SciTech Connect

Pre-storage drying-transfer operations and early stage storage expose cladding to higher temperatures and much higher pressure-induced tensile hoop stresses relative to normal operation in-reactor and pool storage under these conditions. Radial hydrides could precipitate during slow cooling and provide an additional embrittlement mechanism as the cladding temperature decreases below the ductile-to-brittle transition temperature. As a means of simulating this behavior, unirradiated hydrided Zircaloy-4 samples were fabricated by a gas charging method to levels that encompass the range of hydrogen concentrations observed in current used fuel. Mechanical testing was carried out by the ring compression test (RCT) method at various temperatures to evaluate the sample s ductility for both as-hydrided and post-hydride reorientation treated specimens. As-hydrided samples with higher hydrogen concentration (>800 ppm) resulted in lower strain before fracture and reduced maximum load. Increasing RCT temperatures resulted in increased ductility of the as-hydrided cladding. A systematic radial hydride treatment was conducted at various pressures and temperatures for the hydrided samples with H content around 200 ppm. Following the radial hydride treatment, RCTs on the hydride reoriented samples were conducted and exhibited lower ductility compared to as-hydrided samples.

Yan, Yong [ORNL] [ORNL; Plummer, Lee K [ORNL] [ORNL; Ray, Holly B [ORNL] [ORNL; Cook, Tyler S [ORNL] [ORNL; Bilheux, Hassina Z [ORNL] [ORNL

2014-01-01

108

Mercury pollution in China  

SciTech Connect

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 environmental researchers. It addresses issues of mercury pollution from mercury and gold mining, coal combustion and the chemical industry. Data on dietary intake of mercury is also reported. 50 refs., 2 figs., 2 photos.

Gui-Bin Jiang; Jian-Bo Shi; Xin-Bin Feng [Chinese Academy of Sciences (China). State Key Laboratory of Environmental Chemistry and Ecotoxicology

2006-06-15

109

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.

Bob Riddle

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

HYDRIDE-INDUCED EMBRITTLEMENT IN METALS - STRESS AND TEMPERATURE EFFECTS  

Microsoft Academic Search

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

A. G. Varias; A. R. Massih

115

Method of binding a metal hydride to a surface  

SciTech Connect

A system for storing hydrogen in the form of a metal hydride is described comprising a hydride-forming metal which is bound to a surface with a silicone rubber. The system defines a flow path for hydrogen, the hydrogen being directed along the flow path to and from the hydride-forming metal. The system incudes a water sorbent disposed to contact the hydrogen before the hydrogen contacts the silicone rubber, the water sorbent being disposed within the flow path.

Retallick, W.B.; Predecki, P.K.

1989-01-24

116

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

117

The electrochemical impedance of metal hydride electrodes  

Microsoft Academic Search

Electrochemical impedance spectroscopy (EIS) and other characterization methods combined with modelling are very useful tools to gain an understanding of the processes governing the charge and discharge reactions in metal hydride electrodes. Impedance measurements were performed in the range from 10 kHz to 0.1 mHz. The proposed model simulated the experimental data better than previously presented models by a smooth

L. O. Valøen; R. Tunold

2002-01-01

118

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

119

Nickel metal hydride LEO cycle testing  

NASA Technical Reports Server (NTRS)

The George C. Marshall Space Flight Center is working to characterize aerospace AB5 Nickel Metal Hydride (NiMH) cells. The cells are being evaluated in terms of storage, low earth orbit (LEO) cycling, and response to parametric testing (high rate charge and discharge, charge retention, pulse current ability, etc.). Cells manufactured by Eagle Picher are the subjects of the evaluation. There is speculation that NiMH cells may become direct replacements for current Nickel Cadmium cells in the near future.

Lowery, Eric

1995-01-01

120

Materials compatibility of hydride storage materials with austenitic stainless steels  

SciTech Connect

This task evaluated the materials compatibility of LaNi[sub 5-x]Al[sub x] (x= 0.3, 0.75) hydrides and palladium coated kieselguhr with austenitic stainless steel in hydrogen and tritium process environments. Based on observations of retired prototype hydride storage beds and materials exposure testing samples designed for this study, no materials compatibility problem was indicated. Scanning electron microscopy observations of features on stainless steel surfaces after exposure to hydrides are also commonly found on as-received materials before hydriding. These features are caused by either normal heat treating and acid cleaning of stainless steel or reflect the final machining operation.

Clark, E.A.

1992-09-21

121

Materials compatibility of hydride storage materials with austenitic stainless steels  

SciTech Connect

This task evaluated the materials compatibility of LaNi{sub 5-x}Al{sub x} (x= 0.3, 0.75) hydrides and palladium coated kieselguhr with austenitic stainless steel in hydrogen and tritium process environments. Based on observations of retired prototype hydride storage beds and materials exposure testing samples designed for this study, no materials compatibility problem was indicated. Scanning electron microscopy observations of features on stainless steel surfaces after exposure to hydrides are also commonly found on as-received materials before hydriding. These features are caused by either normal heat treating and acid cleaning of stainless steel or reflect the final machining operation.

Clark, E.A.

1992-09-21

122

Storing hydrogen in the form of light alloy hydrides  

NASA Technical Reports Server (NTRS)

Different hydrides are investigated to find a system with a sufficiently high storage density (at least 3%). The formation of hydrides with light alloys is examined. Reaction kinetics for hydride formation were defined and applied to the systems Mg-Al-H, Mg-Al-Cu-H, Ti-Al-H, Ti-Al-Cu-H, and Ti-Al-Ni-H. Results indicate that the addition of Al destabilizes MgH2 and TiH2 hydrides while having only a limited effect on the storage density.

Freund, E.; Gillerm, C.

1981-01-01

123

METAL HYDRIDE HYDROGEN COMPRESSORS: A REVIEW  

SciTech Connect

Metal hydride (MH) thermal sorption compression is an efficient and reliable method allowing a conversion of energy from heat into a compressed hydrogen gas. The most important component of such a thermal engine the metal hydride material itself should possess several material features in order to achieve an efficient performance in the hydrogen compression. Apart from the hydrogen storage characteristics important for every solid H storage material (e.g. gravimetric and volumetric efficiency of H storage, hydrogen sorption kinetics and effective thermal conductivity), the thermodynamics of the metal-hydrogen systems is of primary importance resulting in a temperature dependence of the absorption/desorption pressures). Several specific features should be optimized to govern the performance of the MH-compressors including synchronisation of the pressure plateaus for multi-stage compressors, reduction of slope of the isotherms and hysteresis, increase of cycling stability and life time, together with challenges in system design associated with volume expansion of the metal matrix during the hydrogenation. The present review summarises numerous papers and patent literature dealing with MH hydrogen compression technology. The review considers (a) fundamental aspects of materials development with a focus on structure and phase equilibria in the metal-hydrogen systems suitable for the hydrogen compression; and (b) applied aspects, including their consideration from the applied thermodynamic viewpoint, system design features and performances of the metal hydride compressors and major applications.

Bowman Jr, Robert C [ORNL] [ORNL; Yartys, Dr. Volodymyr A. [Institute for Energy Technology (IFE)] [Institute for Energy Technology (IFE); Lototskyy, Dr. Michael V [University of the Western Cape, South Africa] [University of the Western Cape, South Africa; Pollet, Dr. B.G. [University of the Western Cape, South Africa

2014-01-01

124

Plasmonic hydrogen sensing with nanostructured metal hydrides.  

PubMed

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

Wadell, Carl; Syrenova, Svetlana; Langhammer, Christoph

2014-12-23

125

Mercury Chamber Considerations  

E-print Network

Mercury Chamber Considerations V. Graves IDS-NF Target Studies July 2011 #12;2 Managed by UT-Battelle for the U.S. Department of Energy Mercury Chamber Considerations, July 2011 Flow Loop Review · 1 cm dia nozzle, 20 m/s jet requires 1.57 liter/sec mercury flow (94.2 liter/min, 24.9 gpm). · MERIT experiment

McDonald, Kirk

126

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.

James Grimwood

1963-01-01

127

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

128

Substorms on Mercury?  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

129

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

130

[Study and application of flow injection liquid-liquid extraction non-aqueous media mercury reduction atomic fluorescence spectrometry].  

PubMed

A new method for on-line solvent extraction covalent hydride generation in a non-aqueous media was proposed. Flow injection techniques were used to develop an efficient on-line solvent extraction pre-concentration and pre-separation system. The hydride generation is carried out in an aliquot of metal-complex extraction solution by sodium tetrahydroborate(III) in N,N-dimethyl formamide solution and anhydrons acetic acid. Hg is extracted by KI + HNO3 + (NH2)2CS into TBP and hydride generation by proposed method. A improved u-type gas-liguid separator was used. The working conditions and manifolds scheme of flow injection had been optimized. The method is applied to the determination of mercury in GSD-4 and GSD-6 geological reference materials with good accuracy and precision. PMID:12940050

Guo, Xin; Jin, Ze-xiang; Tang, Zhi-yong

2002-02-01

131

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

Idaho National Laboratory - Mike Abbott

2010-01-08

132

Mercury in the environment  

SciTech Connect

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

Idaho National Laboratory - Mike Abbott

2008-08-06

133

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.

Bill Arnett

134

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...

135

MESSENGER: Exploring Mercury's Magnetosphere  

NASA Technical Reports Server (NTRS)

The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

Slavin, James A.

2008-01-01

136

MERCURY RESEARCH STRATEGY  

EPA Science Inventory

The U.S. Environmental Protection Agency's (EPA's) Office of Research and Development (ORD) is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001 2005 time frame. ORD will use it to ...

137

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

PubMed

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

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

2015-01-01

138

Method of making crack-free zirconium hydride  

DOEpatents

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

Sullivan, Richard W. (Denver, CO)

1980-01-01

139

Hydrogen storage in the form of metal hydrides  

NASA Technical Reports Server (NTRS)

Reversible reactions between hydrogen and such materials as iron/titanium and magnesium/ nickel alloy may provide a means for storing hydrogen fuel. A demonstration model of an iron/titanium hydride storage bed is described. Hydrogen from the hydride storage bed powers a converted gasoline electric generator.

Zwanziger, M. G.; Santana, C. C.; Santos, S. C.

1984-01-01

140

MERCURY MULTI-YEAR PLAN  

EPA Science Inventory

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

141

Mercury Jet Studies Tristan Davenne  

E-print Network

Mercury Jet Studies Tristan Davenne Rutherford Appleton Laboratory Joint UKNF, INO, UKIERI meeting mercury target and reported a radial velocity at surface of mercury jet due to proton beam is 36m/s #12;Numerical simulation of Sievers & Pugnat Result Click on image above to watch video of 2cm mercury target

McDonald, Kirk

142

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 vocational…

1999

143

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

144

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

145

On the High-Pressure Behavior of Titanium Hydride  

NASA Astrophysics Data System (ADS)

Hydrogen storage research has recently invested a great deal of efforts into investigations of metal hydrides. Although titanium hydride is not the ideal candidate for storing hydrogen, Ti hydrides can act as active species to catalyze the reversible dehydrogenation of other hydrides and carbon nanotubes. In addition the basic science interest of this project lies in investigating the structure and especially the high-pressure behavior of TiH2. In the present study, we show the first in situ, high-pressure angle-dispersive and energy dispersive synchrotron x-ray diffraction studies of titanium hydride. We investigate the effects of hydrostatic and non-hydrostatic conditions. We also show the results of structural refinements as well as the bulk modulus of TiH2. To the best of our knowledge, this work is the first attempt to measure the equation of state of TiH2 using synchrotron x-ray diffraction and diamond anvil cells.

Kalita, Patricia E.; Sinogeikin, Stanislas; Lipinska-Kalita, Kristina E.; Hartmann, Thomas; Cornelius, Andrew

2007-03-01

146

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

147

Recent advances in metal hydrides for clean energy applications  

SciTech Connect

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

Ronnebro, Ewa; Majzoub, Eric H.

2013-06-01

148

Modular hydride beds for mobile applications  

SciTech Connect

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

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

1997-08-01

149

Results of NDE Technique Evaluation of Clad Hydrides  

SciTech Connect

This report fulfills the M4 milestone, M4FT-14IN0805023, Results of NDE Technique Evaluation of Clad Hydrides, under Work Package Number FT-14IN080502. During service, zirconium alloy fuel cladding will degrade via corrosion/oxidation. Hydrogen, a byproduct of the oxidation process, will be absorbed into the cladding and eventually form hydrides due to low hydrogen solubility limits. The hydride phase is detrimental to the mechanical properties of the cladding and therefore it is important to be able to detect and characterize the presence of this constituent within the cladding. Presently, hydrides are evaluated using destructive examination. If nondestructive evaluation techniques can be used to detect and characterize the hydrides, the potential exists to significantly increase test sample coverage while reducing evaluation time and cost. To demonstrate the viability this approach, an initial evaluation of eddy current and ultrasonic techniques were performed to demonstrate the basic ability to these techniques to detect hydrides or their effects on the microstructure. Conventional continuous wave eddy current techniques were applied to zirconium based cladding test samples thermally processed with hydrogen gas to promote the absorption of hydrogen and subsequent formation of hydrides. The results of the evaluation demonstrate that eddy current inspection approaches have the potential to detect both the physical damage induced by hydrides, e.g. blisters and cracking, as well as the combined effects of absorbed hydrogen and hydride precipitates on the electrical properties of the zirconium alloy. Similarly, measurements of ultrasonic wave velocities indicate changes in the elastic properties resulting from the combined effects of absorbed hydrogen and hydride precipitates as well as changes in geometry in regions of severe degradation. However, for both approaches, the signal responses intended to make the desired measurement incorporate a number of contributing parameters. These contributing factors need to be recognized and a means to control them or separate their contributions will be required to obtain the desired information.

Dennis C. Kunerth

2014-09-01

150

Highly Concentrated Palladium Hydrides/Deuterides; Theory  

SciTech Connect

Accomplishments are reported in these areas: tight-binding molecular dynamics study of palladium; First-principles calculations and tight-binding molecular dynamics simulations of the palladium-hydrogen system; tight-binding studies of bulk properties and hydrogen vacancies in KBH{sub 4}; tight-binding study of boron structures; development of angular dependent potentials for Pd-H; and density functional and tight-binding calculations for the light-hydrides NaAlH4 and NaBH4

Papaconstantopoulos, Dimitrios

2013-11-26

151

Metal hydride fuel storage and method thereof  

DOEpatents

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

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

2010-08-10

152

An evaluation of the use of metal hydrides for solar thermal energy storage  

Microsoft Academic Search

The basic properties of metal hydrides relevant to their application for storing solar thermal energy are reviewed. Several schemes are discussed and evaluated in which the enthalpy of formation of a primary hydride is used to provide heat and a secondary hydride or compressed gas is utilized for hydrogen storage. The results show that, with present technology, a metal hydride-based

G. G. Libowitz; Z. Blank

1976-01-01

153

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

154

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

155

Hair mercury concentrations and associated factors in an electronic waste recycling area, Guiyu, China  

SciTech Connect

Objective: Toxic heavy metals are released to the environment constantly from unregulated electronic waste (e-waste) recycling in Guiyu, China, and thus may contribute to the elevation of mercury (Hg) and other heavy metals levels in human hair. We aimed to investigate concentrations of mercury in hair from Guiyu and potential risk factors and compared them with those from a control area where no e-waste processing occurs. Methods: A total of 285 human hair samples were collected from three villages (including Beilin, Xianma, and Huamei) of Guiyu (n=205) and the control area, Jinping district of Shantou city (n=80). All the volunteers were administered a questionnaire regarding socio-demographic characteristics and other possible factors contributed to hair mercury concentration. Hair mercury concentration was analyzed by hydride generation atomic fluorescence spectrometry (AFS). Results: Our results suggested that hair mercury concentrations in volunteers of Guiyu (median, 0.99; range, 0.18–3.98 ?g/g) were significantly higher than those of Jinping (median, 0.59; range, 0.12–1.63 ?g/g). We also observed a higher over-limit ratio (>1 ?g/g according to USEPA) in Guiyu than in Jinping (48.29% vs. 11.25%, P<0.001). Logistic regression model showed that the variables of living house also served as an e-waste workshop, work related to e-waste, family income, time of residence in Guiyu, the distance between home and waste incineration, and fish intake were associated with hair mercury concentration. After multiple stepwise regression analysis, in the Guiyu samples, hair mercury concentration was found positively associated with the time residence in Guiyu (?=0.299, P<0.001), and frequency of shellfish intake (?=0.184, P=0.016); and negatively associated with the distance between home and waste incineration (?=?0.190, P=0.015) and whether house also served as e-waste workshop (?=?0.278, P=0.001). Conclusions: This study investigated human mercury exposure and suggested elevated hair mercury concentrations in an e-waste recycling area, Guiyu, China. Living in Guiyu for a long time and work related to e-waste may primarily contribute to the high hair mercury concentrations. -- Highlights: • Mercury levels in hair samples from Guiyu and risk factors were assessed. • The recruitments from Guiyu were exposed to high levels of mercury. • Primitive e-waste recycling resulted in high mercury exposure of local people.

Ni, Wenqing [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)] [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Chen, Yaowen [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China)] [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China); Huang, Yue; Wang, Xiaoling [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)] [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Zhang, Gairong [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China)] [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China); Luo, Jiayi [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)] [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Wu, Kusheng, E-mail: kswu@stu.edu.cn [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)] [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)

2014-01-15

156

New horizons in boron hydride chemistry  

SciTech Connect

Pentaborane and diborane undergo hydrogen isotope exchange with deuterated aromatic hydrocarbons. Lewis acid catalyzed hydrogen isotope exchange between benzene-d/sub 6/ and pentaborane forms exclusively 1-DB/sub 5/H/sub 8/ at ambient temperature. In uncatalyzed exchanges, pentaborane reacts with benzene-d/sub 6/ to produce 1,2,3,4,5-D/sub 5/B/sub 5/H/sub 4/ at +45/sup 0/C, and B/sub 5/D/sub 9/ at + 120/sup 0/C. This thermally induced hydrogen isotope exchange apparently occurs via a reversible hydroboration of the aromatic ring. Halopentaboranes are converted to the parent pentaborane using tributyltin hydride as the halogen reducing agent under mild conditions and in high yields. Tributyltin hydride also reacts with other haloboranes and halometalloboranes. Deuterated pentaboranes are produced from halopentaboranes and tributyltin deuteride. Mechanistic features of this hydrogen-halogen exchange system are discussed. A new aminoborane, bis(dimethylamino)tetraborane, has been synthesized. On the basis of physical and spectroscopic data, a structure having the classical tetraborane framework is proposed, with two bridge hydrogen atoms replaced by dimethylamino groups. Solvent and temperature effects on the /sup 11/B and /sup 1/H NMR spectra of decaborane have been observed. Solvent polarizability is the major factor affecting chemical shifts. /sup 11/B-/sup 1/H/sub bridge/ and /sup 11/B-/sup 11/B coupling in decaborane can be measured at the B position.

Kunz, J.C.

1985-01-01

157

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.

158

A study of hydriding kinetics of metal hydrides using a physically based model  

NASA Astrophysics Data System (ADS)

The reaction of hydrogen with metals to form metal hydrides has numerous potential energy storage and management applications. The metal hydrogen system has a high volumetric energy density and is often reversible with a high cycle life. The stored hydrogen can be used to produce energy through combustion, reaction in a fuel cell, or electrochemically in metal hydride batteries. The high enthalpy of the metal-hydrogen reaction can also be used for rapid heat removal or delivery. However, improving the often poor gravimetric performance of such systems through the use of lightweight metals usually comes at the cost of reduced reaction rates or the requirement of pressure and temperature conditions far from the desired operating conditions. In this work, a 700 bar Sievert system was developed at the Purdue Hydrogen Systems Laboratory to study the kinetic and thermodynamic behavior of high pressure hydrogen absorption under near-ambient temperatures. This system was used to determine the kinetic and thermodynamic properties of TiCrMn, an intermetallic metal hydride of interest due to its ambient temperature performance for vehicular applications. A commonly studied intermetallic hydride, LaNi5, was also characterized as a base case for the phase field model. The analysis of the data obtained from such a system necessitate the use of specialized techniques to decouple the measured reaction rates from experimental conditions. These techniques were also developed as a part of this work. Finally, a phase field model of metal hydride formation in mass-transport limited interstitial solute reactions based on the regular solution model was developed and compared with measured kinetics of LaNi5 and TiCrMn. This model aided in the identification of key reaction features and was used to verify the proposed technique for the analysis of gas-solid reaction rates determined volumetrically. Additionally, the phase field model provided detailed quantitative predictions of the effects of multidimensional phase growth and transitions between rate-limiting processes on the experimentally determined reaction rates. Unlike conventional solid state reaction analysis methods, this model relies fully on rate parameters based on the physical mechanisms occurring in the hydride reaction and can be extended to reactions in any dimension.

Voskuilen, Tyler G.

159

Hot temperatures line lists for metal hydrides  

NASA Astrophysics Data System (ADS)

The ExoMol project is an ERC funded project set up with the purpose of calculating high quality theoretical molecular line list data to facilitate the emerging field of exoplanet and cool star atmospheric haracterisation [1]. Metal hydrides are important building blocks of interstellar physical chemistry. For molecular identification and characterisation in astrophysical sources, one requires accurate and complete spectroscopic data including transitional frequencies and intensities in the form of a line list. The ab initio methods offer the best opportunity for detailed theoretical studies of free diatomic metal hydrides and other simple hydride molecules. In this contribution we present progress on theoretical line lists for AlH, CrH, MgH, NiH, NaH and TiH obtained from first principles, applicable for a large range of temperatures up to 3500 K. Among the hydrides, AlH is of special interest because of a relatively high cosmic abundance of aluminium. The presence of AlH has been detected in the spectra of M-type and S-type stars as well as in sunspots (See [2] and references therein). CrH is a molecule of astrophysical interest; under the classification scheme developed by Kirkpatrick et al [3], CrH is of importance in distinguishing L type brown dwarfs. It has been proposed that theoretical line-lists of CrH and CrD could be used to facilitate a 'Deuterium test' for use in distinguishing planets, brown dwarfs and stars [5] and also it has been speculated that CrH exists in sunspots [4] but a higherquality hot-temperature line-list is needed to confirm this finding. The presence of MgH in stellar spectra is well documented through observation of the A2 ! X 2+ and B0 2+ ! X 2+ transitions. Different spectral features of MgH have been used as an indicator for the magnesium isotope abundances in the atmospheres of different stars from giants to dwarfs including the Sun, to measure the temperature of stars, surface gravity, stars' metal abundance, gravitational, as well as for a deuterium test (see [6] and references therein). MgH is an important part of stellar atmospheric models. NiH is predicted to be the most common nickelbearing molecule [7] and was indentified in sunspot spectra around 15 000 cm-1 (646 cm) over 40 years ago [8]. Knowledge of 58NiH/60NiH isotopologue ratio in stellar spectra is used to test models of supernovae and star formation [9]. The spectra of metal hydrides such can be very complicated due to the large-number of interacting electronic states, to the importance of electron correlation, relativistic and spin-orbit effects and of the various couplings between angular momenta. Via the use of the Born-Oppenheimer approximation, the Schrödinger equation describing the state of a molecule can be factorised into an 'electronic' component and a nuclear (i.e., rotational-vibrational) component. The former is solved using the ab initio quantum chemistry package MOLPRO, yielding potential energy, dipole and transition moment, and spin-orbit curves. The resulting coupled-surface ro-vibronic problem was then solved using the in-house computer program DUO, which is based on expansion in Hund's case (a) wave functions. Potential curves and couplings were then refined semi-empirically using the available experimental spectroscopic data.

Gorman, M.; Lodi, L.; Leyland, P. pC; Hill, C.; Yurchenko, S. N.; Tennyson, J.

2013-09-01

160

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

PubMed

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

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

2015-02-01

161

Fracture Resistance of a Zirconium Alloy with Reoriented Hydrides  

NASA Astrophysics Data System (ADS)

Zirconium alloy cladding materials typically contain circumferential hydrides that may be reoriented to align along the radial direction when the cladding tubes are heated above and then cooled below the solvus temperature. The objectives of this study were to investigate the critical stress levels required to cause hydride reorientation (HRT) and to characterize the fracture resistance of Zircaloy-2 after hydride reorientation. HRT heat-treatment was performed on hydrogen-charged Zircaloy-2 specimens at 593 K (320 °C) or 623 K (350 °C) for 1 to 2 hours, followed by cooling to 473 K (200 °C). Fracture testing was conducted on hydride-reoriented three-point bend specimens at 473 K (200 °C) using an in situ loading stage inside a scanning electron microscope. Direct observations indicated that the reoriented hydrides, which ranged from ?1 to 22 ?m in lengths, were more prone to fracture at larger sizes (>10 ?m) compared to smaller sizes (<0.5 ?m). The reoriented hydrides reduced fracture resistance through a void nucleation, growth, and coalescence process at the crack tip. The resulting crack-resistance curves for Zircaloy-2 with reoriented hydrides decrease from 38 to 21 MPa(m)1/2 with increasing hydrogen contents from 51 to 1265 wt ppm hydrogen.

Chan, Kwai S.; He, Xihua; Pan, Yi-Ming

2015-01-01

162

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

163

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

164

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

165

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

166

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

167

Filiform-mode hydride corrosion of uranium surfaces  

NASA Astrophysics Data System (ADS)

Hydride nucleation and growth has previously been studied in uranium with an air-formed oxide. Preferred directional growth of uranium hydride has not been observed, presumably due to the constraint of the oxide layer and/or the presence of a surface layer distorted by mechanical grinding and polishing. Instead, hydrides typically first form as subsurface blisters that do not exhibit preferred growth directionality. By eliminating the strained surface layer through electropolishing, removing the natural oxide through ion sputtering, avoiding exposure of the uranium to air, and then exposing uranium to high purity hydrogen in an environmental cell, hydride growth patterns emerge that correspond to defect structures within the microstructure. These hydride growth patterns are similar to filiform corrosion, a type of corrosion that frequently forms under thin protective films. This work describes the first reported observation of filiform-like corrosion in uranium. The uranium hydride initiates at defects, but grows into filaments up to 20 ?m wide, and tends to form in straight lines, largely propagating along twin boundaries. Propagation is driven by hydrogen reaction at the filament head, promoted by more efficient delivery of reactant. However, this phenomenon does not involve an electrochemical process associated with conventional filiform corrosion and is therefore described as filiform-like. Hydride growth was observed using optical microscopy for a period of nearly three years. Sample characterization included automated electron backscatter diffraction (EBSD) measurements to determine growth directions. Observation of this anomalous hydride growth provides clues as to the mechanisms operating in uranium hydriding for more conventionally prepared sample surfaces.

Hill, M. A.; Schulze, R. K.; Bingert, J. F.; Field, R. D.; McCabe, R. J.; Papin, P. A.

2013-11-01

168

Mercury Releases and Spills  

MedlinePLUS

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

169

Mercury and Pregnancy  

MedlinePLUS

... that contain high amounts of mercury. These include shark, swordfish, king mackerel and tilefish. If you need ... is mostly found in large fish, like swordfish, shark, king mackerel and tilefish. During pregnancy, don’t ...

170

Group IV a metal hydride catalysts and preparation thereof  

SciTech Connect

Benzene, or an alkylbenzene, is hydrogenated by reaction with hydrogen in the presence of a Group IVa or Va metal hydride catalyst. The catalyst may be a simple hydride such as ZrH/sub 2/ or a hydride of an alloy such as Cu/sub 3/Zr or may be a complex material. One complex material is the reaction product of a Group IVa or Va metal halide, such as ZrCl/sub 4/ with an alkyllithium or aryllithium, such as n-butyllithium, in a hydrocarbon solvent.

Pez, G. P.

1985-04-30

171

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

172

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

173

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

174

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.

175

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

176

Hydride affinity scale of various substituted arylcarbeniums in acetonitrile.  

PubMed

Combined with the integral equation formalism polarized continuum model (IEFPCM), the hydride affinities of 96 various acylcarbenium ions in the gas phase and CH(3)CN were estimated by using the B3LYP/6-31+G(d)//B3LYP/6-31+G(d), B3LYP/6-311++G(2df,2p)//B3LYP/6-31+G(d), and BLYP/6-311++G(2df,2p)//B3LYP/6-31+G(d) methods for the first time. The results show that the combination of the BLYP/6-311++G(2df,2p)//B3LYP/6-31+G(d) method and IEFPCM could successfully predict the hydride affinities of arylcarbeniums in MeCN with a precision of about 3 kcal/mol. On the basis of the calculated results from the BLYP method, it can be found that the hydride affinity scale of the 96 arylcarbeniums in MeCN ranges from -130.76 kcal/mol for NO(2)-PhCH(+)-CN to -63.02 kcal/mol for p-(Me)(2)N-PhCH(+)-N(Me)(2), suggesting most of the arylcarbeniums are good hydride acceptors. Examination of the effect of the number of phenyl rings attached to the carbeniums on the hydride affinities shows that the increase of the hydride affinities takes place linearly with increasing number of benzene rings in the arylcarbeniums. Analyzing the effect of the substituents on the hydride affinities of arylcarbeniums indicates that electron-donating groups decrease the hydride affinities and electron-withdrawing groups show the opposite effect. The hydride affinities of arylcarbeniums are linearly dependent on the sum of the Hammett substituent parameters ?(p)(+). Inspection of the correlation of the solution-phase hydride affinities with gas-phase hydride affinities and aqueous-phase pK(R)(+) values reveals a remarkably good correspondence of ?G(H(-)A)(R(+)) with both the gas-phase relative hydride affinities only if the ? substituents X have no large electron-donating or -withdrawing properties and the pK(R)(+) values even though the media are dramatically different. The solution-phase hydride affinities also have a linear relationship with the electrophilicity parameter E, and this dependence can certainly serve as one of the most effective ways to estimate the new E values from ?G(H(-)A)(R(+)) or vice versa. Combining the hydride affinities and the reduction potentials of the arylcarbeniums, we obtained the bond homolytic dissociation Gibbs free energy changes of the C-H bonds in the corresponding hydride adducts in acetonitrile, ?G(HD)(RH), and found that the effects of the substituent on ?G(HD)(RH) are very small. Simple thermodynamic analytic platforms for the three C-H cleavage modes were constructed. It is evident that the present work would be helpful in understanding the nature of the stabilities of the carbeniums and mechanisms of the hydride transfers between carbeniums and other hydride donors. PMID:21117661

Zhu, Xiao-Qing; Wang, Chun-Hua

2010-12-23

177

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.

178

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

179

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

180

Mercury CEM Calibration  

SciTech Connect

Mercury continuous emissions monitoring systems (CEMS) are being implemented in over 800 coal-fired power plant stacks. The power industry desires to conduct at least a full year of monitoring before the formal monitoring and reporting requirement begins on January 1, 2009. It is important for the industry to have available reliable, turnkey equipment from CEM vendors. 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 generators 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 requires that calibration be performed with NIST-traceable standards (Federal Register 2007). 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 an interim traceability protocol for elemental mercury generators (EPA 2007). 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 document is divided into two separate sections. The first deals with the qualification of generators by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the generator models that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry performed by NIST in Gaithersburg, MD. The outputs of mercury generators are compared to one another using a nesting procedure which allows direct comparison of one generator with another and eliminates analyzer variability effects. The qualification portion of the EPA interim traceability protocol requires the vendors to define generator performance as affected by variables such as pressure, temperature, line voltage, and shipping. WRI is focusing efforts to determine actual generator performance related to the variables defined in the qualification portion of the interim protocol. The protocol will then be further revised by EPA based on what can actually be achieved with the generators. Another focus of the study is to evaluate approaches for field verification of generator performance. Upcoming work includes evaluation of oxidized mercury calibration generators, for which a separate protocol will be prepared by EPA. In addition, the variability of the spectrometers/analyzers under various environmental conditions needs to be defined and understood better. A main objective of the current work is to provide data on the performance and capabilities of elemental mercury generator/calibration systems for the development of realistic NIST traceability protocols for mercury vapor standards for continuous emission CEM calibration. This work is providing a direct contribution to the enablement of continuous emissions monitoring at coal-fired power plants in conformance with the CAMR. EPA Specification 12 states that mercury CEMs must be calibrated with NIST-traceable standards (Federal Register 2005). The initial draft of an elemental mercury generator traceability protocol was circulated by EPA in May 2007 for comment, and an interim protocol was issued in August 2007 (EPA 2007). Initially it was assumed that the calibration and implementation of mercury CEMs would be relatively simple, and implementation would follow the implementation of the Clean Air Interstate Rule (CAIR) SO{sub 2} and NO{sub x} monitoring, and sulfur emissions cap and trade. However, mercury has proven to be significantly more difficult

John Schabron; Joseph Rovani; Mark Sanderson

2008-02-29

181

GEOCHEMICAL FACTORS GOVERNING METHYL MERCURY PRODUCTION IN MERCURY CONTAMINATED SEDIMENTS  

EPA Science Inventory

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

182

Process for production of a metal hydride  

DOEpatents

A process for production of a metal hydride compound MH.sub.x, wherein x is one or two and M is an alkali metal, Be or Mg. The process comprises combining a compound of formula (R.sup.1O).sub.xM with aluminum, hydrogen and at least one metal selected from among titanium, zirconium, hafnium, niobium, vanadium, tantalum and iron to produce a compound of formula MH.sub.x. R.sup.1 is phenyl or phenyl substituted by at least one alkyl or alkoxy group. A mole ratio of aluminum to (R.sup.1O).sub.xM is from 0.1:1 to 1:1. The catalyst is present at a level of at least 200 ppm based on weight of aluminum.

Allen, Nathan Tait; Butterick, III, Robert; Chin, Arthur Achhing; Millar, Dean Michael; Molzahn, David Craig

2014-08-12

183

Zirconium Hydride Space Power Reactor design.  

NASA Technical Reports Server (NTRS)

The Zirconium Hydride Space Power Reactor being designed and fabricated at Atomics International is intended for a wide range of potential applications. Throughout the program a series of reactor designs have been evaluated to establish the unique requirements imposed by coupling with various power conversion systems and for specific applications. Current design and development emphasis is upon a 100 kilowatt thermal reactor for application in a 5 kwe thermoelectric space power generating system, which is scheduled to be fabricated and ground tested in the mid 70s. The reactor design considerations reviewed in this paper will be discussed in the context of this 100 kwt reactor and a 300 kwt reactor previously designed for larger power demand applications.

Asquith, J. G.; Mason, D. G.; Stamp, S.

1972-01-01

184

Novel Hydride Transfer Catalysis for Carbohydrate Conversions  

SciTech Connect

5-Hydroxymethylfurfural (HMF), an important versatile sugar derivative has been synthesized from glucose using catalytic amounts of CrCl2 in 1-ethyl-3-methylimidizolium chloride. Glycerol and glyceraldehyde were tested as sugar model compounds. Glycerol is unreactive and does not interfere with glucose conversion. Glyceraldehyde is reactive and does interfere with glucose conversion in competitive experiments. MnCl2 or FeCl2 catalyze dehydration of glyceraldehyde dimer to form compound I, a cyclic hemiacetal with an exocyclic double bond. Upon aqueous work-up I forms pyruvaldehyde. CrCl2 or VCl3 further catalyze a hydride transfer of I to form lactide. Upon aqueous work-up lactide is converted to lactic acid.

Holladay, John E.; Brown, Heather M.; Appel, Aaron M.; Zhang, Z. Conrad

2008-04-03

185

Ni/metal hydride secondary element  

SciTech Connect

A Ni/metal hydride secondary element having a positive nickel hydroxide electrode, a negative electrode having a hydrogen storage alloy, and an alkaline electrolyte, the positive electrode, provided with a three-dimensional metallic conductive structure, also contains an aluminum compound which is soluble in the electrolyte, in addition to nickel hydroxide and cobalt oxide. The aluminum compound is aluminum hydroxide and/or aluminum oxide, and the mass of the aluminum compound which is present in the positive bulk material mixture is 0.1 to 2% by weight relative to the mass of the nickel hydroxide which is present. In combination with aluminum hydroxide or aluminum oxide, the positive electrode further contains lanthanoid oxidic compounds Y.sub.2 O.sub.3, La.sub.2 O.sub.3 and Ca(OH).sub.2, as well as mixtures of these compounds.

Bauerlein, Peter

2005-04-19

186

Long-term pressure and thermal cycling studies on lithium imide-lithium amide complex hydrides and vanadium-carbon hydrides, and electrochemical hydrogen permeation studies  

Microsoft Academic Search

Solid-state hydrogen storage is becoming increasingly important for future development of non-polluting vehicular fuels and nuclear technology. Understanding the nature of classical and complex hydrides is of great importance in developing new high gravimetric or volumetric capacity hydrides. Towards the nuclear technology, we have studied vanadium hydrides with lattice impurities for high volumetric capacities and very low pressures. For the

Joshua H. Lamb

2008-01-01

187

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

188

Bipolar Nickel-Metal Hydride Battery Being Developed  

NASA Technical Reports Server (NTRS)

The NASA Lewis Research Center has contracted with Electro Energy, Inc., to develop a bipolar nickel-metal hydride battery design for energy storage on low-Earth-orbit satellites. The objective of the bipolar nickel-metal hydride battery development program is to approach advanced battery development from a systems level while incorporating technology advances from the lightweight nickel electrode field, hydride development, and design developments from nickel-hydrogen systems. This will result in a low-volume, simplified, less-expensive battery system that is ideal for small spacecraft applications. The goals of the program are to develop a 1-kilowatt, 28-volt (V), bipolar nickel-metal hydride battery with a specific energy of 100 watt-hours per kilogram (W-hr/kg), an energy density of 250 W-hr/liter and a 5-year life in low Earth orbit at 40-percent depth-of-discharge.

Manzo, Michelle A.

1998-01-01

189

Life test results of hydride compressors for cryogenic refrigerators  

NASA Astrophysics Data System (ADS)

A development status assessment is made, from the viewpoint of system durability, for the hydride compressors used in such cryogenic refrigerators as that of the JPL, which has operated at 29 K for 500 hours and at lower temperatures for over 1000. Attention is given to a novel hydride compressor unit which has operated through 35,000 cycles and exhibits negligible degradation of check valves, hydride particle size, and expansion valves. The power requirement for liquid hydrogen cooling can be halved through the use of recuperative hot water heating methods, making this system comparable in power use to liquid hydrogen refrigeration systems operating on electricity. Due to the lack of moving parts in hydride refrigerator designs, potential service lifetimes of many years, and perhaps decades, are being projected.

Jones, J. A.; Golben, P. M.

1984-01-01

190

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

191

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

192

MESSENGER: Exploring Mercury's Magnetosphere  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

193

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

2014-04-01

194

Bioaccumulation of Mercury in Sharks  

E-print Network

Bioaccumulation of Mercury in Sharks Part 1 b After you finish the video and the above questions by humans) sources. 2. How does mercury travel from its source into the tissue of sharks? 3. What are some

Miami, University of

195

Mercury (Environmental Health Student Portal)  

MedlinePLUS

... on mercury: EPA's role, publications, and protecting yourself. Games and Activities The Road to Toxicity (ACADIA Learning for Participatory SCIENCE) - Downloadable board game to teach facts about Mercury and its effect ...

196

Method of selective reduction of polyhalosilanes with alkyltin hydrides  

DOEpatents

The invention relates to the selective and stepwise reduction of polyhalosilanes by reacting at room temperature or below with alkyltin hydrides without the use of free radical intermediates. Alkyltin hydrides selectively and stepwise reduce the Si--Br, Si--Cl, or Si--I bonds while leaving intact any Si--F bonds. When two or more different halogens are present on the polyhalosilane, the halogen with the highest atomic weight is preferentially reduced.

Sharp, Kenneth G. (Midland, MI); D'Errico, John J. (Fenton, MI)

1989-01-01

197

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

198

Mercury's magnetic field and interior  

NASA Technical Reports Server (NTRS)

The magnetic-field data collected on Mercury by the Mariner-10 spacecraft present substantial evidence for an intrinsic global magnetic field. However, studies of Mercury's thermal evolution show that it is most likely that the inner core region of Mercury solidified or froze early in the planet's history. Thus, the explanation of Mercury's magnetic field in the framework of the traditional planetary dynamo is less than certain.

Connerney, J. E. P.; Ness, N. F.

1988-01-01

199

Effect of niobium additions on initial hydriding kinetics of uranium  

NASA Astrophysics Data System (ADS)

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

Li, Ruiwen; Wang, Xiaolin

2014-06-01

200

Electronic structure, bonding and chemisorption in metallic hydrides  

SciTech Connect

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

Ward, J.W.

1980-01-01

201

Optimization of Hydride Rim Formation in Unirradiated Zr 4 Cladding  

SciTech Connect

The purpose of this work is to build on the results reported in the M2 milestone M2FT 13PN0805051, document number FCRD-USED-2013-000151 (Hanson, 2013). In that work, it was demonstrated that unirradiated samples of zircaloy-4 cladding could be pre-hydrided at temperatures below 400°C in pure hydrogen gas and that the growth of hydrides on the surface could be controlled by changing the surface condition of the samples and form a desired hydride rim on the outside diameter of the cladding. The work performed at Pacific Northwest National Laboratory since the issuing of the M2 milestone has focused its efforts to optimize the formation of a hydride rim on available zircaloy-4 cladding samples by controlling temperature variation and gas flow control during pre-hydriding treatments. Surface conditioning of the outside surface was also examined as a variable. The results of test indicate that much of the variability in the hydride thickness is due to temperature variation occurring in the furnaces as well as how hydrogen gas flows across the sample surface. Efforts to examine other alloys, gas concentrations, and different surface conditioning plan to be pursed in the next FY as more cladding samples become available

Shimskey, Rick W.; Hanson, Brady D.; MacFarlan, Paul J.

2013-09-30

202

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

203

Terminal Hydride in [FeFe]-Hydrogenase Model Has Lower Potential for H2 Production Than the Isomeric Bridging Hydride  

PubMed Central

Protonation of the symmetrical tetraphosphine complexes Fe2(S2CnH2n)(CO)2(dppv)2 afforded the corresponding terminal hydrides, establishing that even symmetrical diiron(I) dithiolates undergo protonation at terminal sites. The terminal hydride [HFe2(S2C3H6)(CO)2(dppv)2]+ was found to catalyze proton reduction at potentials 200 mV milder than the isomeric bridging hydride, thereby establishing a thermodynamic advantage for catalysis operating via terminal hydride. The azadithiolate protonates to afford, [Fe2[(SCH2)2NH2](CO)2(dppv)2]+, [HFe2[(SCH2)2NH](CO)2?(dppv)2]+, and [HFe2[(SCH2)2NH2](CO)2(dppv)2]2+, depending on conditions. PMID:18333613

Barton, Bryan E.; Rauchfuss, Thomas B.

2008-01-01

204

Mercury after three MESSENGER flybys  

Microsoft Academic Search

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

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

2010-01-01

205

Student Exposure to Mercury Vapors.  

ERIC Educational Resources Information Center

Discusses the problem of mercury vapors caused by spills in high school and college laboratories. Describes a study which compared the mercury vapor levels of laboratories in both an older and a newer building. Concludes that the mercurial contamination of chemistry laboratories presents minimal risks to the students. (TW)

Weber, Joyce

1986-01-01

206

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 ...

207

Mercury-Related Materials Studies  

E-print Network

Mercury-Related Materials Studies Van Graves IDS NF Ph M tiIDS-NF Phone Meeting Jan 26, 2010 #12 Evaluation of Cavitation Resistance of Type 316LN Stainless Steel in Mercury Using a Vibratory Horn," J. Nucl Pump Impeller Materials for Mercury Service at the Spallation Neutron Source," Oak Ridge National

McDonald, Kirk

208

Mercury-Related Materials Studies  

E-print Network

Mercury-Related Materials Studies Van Graves IDS NF Ph M tiIDS-NF Phone Meeting Jan 26, 2010. Manneschmidt, Preliminary Evaluation of Cavitation Resistance of Type 316LN Stainless Steel in Mercury Using. Pawel, "Assessment of Cavitation-Erosion Resistance of Potential Pump Impeller Materials for Mercury

McDonald, Kirk

209

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...

210

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...

211

Generation of selenium hydride from alkaline solutions: a new concept of the hydride generation-atomic absorption technique  

PubMed Central

The use of hydride generation is often useful in environmental analysis. The normal acid sodium tetrahydroborate reaction provides exceptional sensitivity with continuous flow hydride generators. In some situations there are interferences which will mask the sensitivity. An alternative chemistry system is described here and is shown to offer similar sensitivity to that normally used. A commercial continuous flow analyser is used in this work. PMID:18925246

Bye, Ragnar

1989-01-01

212

Reference Atmosphere for Mercury  

NASA Technical Reports Server (NTRS)

We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

Killen, Rosemary M.

2002-01-01

213

Evaluating zirconium-zirconium hydride interfacial strains by nano-beam electron diffraction  

NASA Astrophysics Data System (ADS)

Nano-beam electron diffraction has been used to quantify the elastic strain field associated with ?-hydride needles embedded in an ?-Zr matrix. It has been found that the volume misfit associated with precipitation results in elastic strains that are ˜4× greater in the matrix than the hydride. Electron energy loss spectroscopy was used to detect hydrogen enrichment at the matrix-hydride interface by a shift in the zirconium plasmon peak. This work highlights that ?-hydride is metastable and acts as a precursor to equilibrium ?-hydride and that compositional variations within the hydride can be detected using electron energy loss spectroscopy.

Barrow, A. T. W.; Korinek, A.; Daymond, M. R.

2013-01-01

214

13. Mercury speciation in biological matrices  

Microsoft Academic Search

In nature, mercury occurs in several forms, e.g.metallic mercury, inorganic mercury and organic mercury compounds. All forms of mercury are considered poisonous, but methyl-mercury is of particular concern since it is extremely toxic and is frequently found in the environment. Through a very effective biomagnification mechanism, methyl-mercury is enriched in food chains which results in high levels in top predators,

I. Drabæk; Á. Iverfeldt

1995-01-01

215

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

216

Water displacement mercury pump  

DOEpatents

A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

Nielsen, M.G.

1984-04-20

217

Water displacement mercury pump  

DOEpatents

A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

Nielsen, Marshall G. (Woodside, CA)

1985-01-01

218

High vacuum mercury retort recovery  

SciTech Connect

Bethlehem Apparatus Company is a worldwide supplier of extremely high purity quadruple distilled mercury. For 40 years, the process of continuous feed vacuum distillation of mercury has been used to achieve the highest levels of purity. In the early 1970`s Bethlehem developed a mercury retort process for the recovery of mercury from manufactured articles. This process is continuously updated with new innovations and is currently a relatively high vacuum system that is capable of handling a wide variety of mercury bearing waste materials.

Boyle, J.M. [Bethlehem Apparatus Co., Inc., Hellertown, PA (United States)

1995-12-31

219

The Mercury atmosphere  

NASA Technical Reports Server (NTRS)

Data available on the composition of Mercury's atmosphere are reviewed, and the sources of these atmospheric components are considered. The known gaseous components in Mercury's atmosphere are H, He, O, Na, and K; among other gases likely to be present are H2 and H2O. Probable sources of these components are the solar wind for hydrogen and helium. The alkalis and water are considered to come from the evaporation of meteoroidal material, with a possible contribution to the former by sputtering and photosputtering.

Hunten, D. M.; Shemansky, D. E.; Morgan, T. H.

1988-01-01

220

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.

221

Influence of uranium hydride oxidation on uranium metal behaviour  

SciTech Connect

This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

2013-07-01

222

The feasibility of a laser based on the mercury hydride molecule  

NASA Astrophysics Data System (ADS)

The processes of formation and destruction of A2Pi 1/2 and X2Sigma 1/2 states in a HgH molecule inside a dense Hg-H-He(N2,CO) plasma have been investigated experimentally. The dynamic behavior of the HgH molecule luminescence is measured as a function of plasma density; plasma composition; absorption of the radiation from the most intense HgH bands; and quenching of the first electronically-excited A2Pi 1/2 (v = 0,1) and A2Pi 3/2 states. Analysis of the experimental data showed that the dense chemical reaction of excited HgH(A) formation occurs at a high rate in the absence of precipitation of HgH (X) and without destruction of HgH (X) by CO molecules. A conclusion is offered concerning the validity of the assumed kinetic model of the HgH laser.

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

1985-12-01

223

Mercury poisoning as a mining hazard  

Microsoft Academic Search

A review is presented of the occurrence of mercury poisoning in personnel engaged in mercury mining and allied industries. Methods for diagnosis and protection against mercury poisoning are discussed. It is pointed out that in industrial mercury poisoning the portals of entry to the body may include skin absorption from dust on the body or clothing, inhalation of mercury dust

S. J. Davenport; D. Harrington

1941-01-01

224

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

225

Synthesis and small molecule chemistry of the niobaziridine-hydride functional group  

E-print Network

Chapter 1. Synthesis and Divergent Reactivity of the Niobaziridine-Hydride Functional Group The synthesis, characterization and reactivity of the niobaziridine-hydride complex Nb(H)([eta]²-t- ]Bu(H)C=NAr)(N[Np]Ar)? (la-H; ...

Figueroa, Joshua S

2005-01-01

226

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

E-print Network

PREPRINT submitted to Journal of Physics B Electronic structure of the Magnesium hydride molecular: 31.15.AR,31.15.Ct,31.50.Be,31.50.Df #12; Electronic structure of the Magnesium hydride molecular ion

Recanati, Catherine

227

Hydrogen storage as a hydride. Citations from the International Aerospace Abstracts data base  

NASA Technical Reports Server (NTRS)

These citations from the international literature concern the storage of hydrogen in various metal hydrides. Binary and intermetallic hydrides are considered. Specific alloys discussed are iron titanium, lanthanium nickel, magnesium copper and magnesium nickel among others.

Zollars, G. F.

1980-01-01

228

CRYSTALLOGRAPHIC PROPERTIES AND MECHANICAL BEHAVIOR OF TITANIUM HYDRIDE LAYERS GROWN ON TITANIUM IMPLANTS  

E-print Network

CRYSTALLOGRAPHIC PROPERTIES AND MECHANICAL BEHAVIOR OF TITANIUM HYDRIDE LAYERS GROWN ON TITANIUM, Switzerland Keywords: SLA treated titanium - bone-anchored dental implants - transmission and scanning electron microscopy - titanium hydride sub-surface layer - epitaxy Abstract Commercially pure titanium

Paris-Sud XI, Université de

229

Permeation rates for RTF metal hydride vessels  

SciTech Connect

Contamination rates have been estimated for the RTF nitrogen heating and cooling system (NH and CS) due to tritium permeation through the walls of metal hydride vessels. Tritium contamination of the NH and CS will be seen shortly after start-up of the RTF with the majority of it coming from the TCAP units. Contamination rates of the NH and CS are estimated to exceed 400 Ci/year after three years of operation and will elevate tritium concentrations in the NH and CS above 6 {times} 10{sup {minus}3} {mu}Ci/cc. To reduce tritium activity in the NH and CS, a stripper or ``getter`` bed may need to be installed in the NH and CS. Increasing the purge rate of nitrogen from the NH and CS is shown to be an impractical method for reducing tritium activity due to the high purge rates required. Stripping of the NH and CS nitrogen in the glove box stripper system will give a temporary lowering of tritium activity in the NH and CS, but tritium activity will return to its previous level in approximately two weeks.

Klein, J.E.

1992-05-21

230

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

231

Predicting mercury in mallard ducklings from mercury in chorioallantoic membranes  

USGS Publications Warehouse

Methylmercury has been suspected as a cause of impaired reproduction in wild birds, but the confounding effects of other environmental stressors has made it difficult to determine how much mercury in the eggs of these wild species is harmful. Even when a sample egg can be collected from the nest of a wild bird and the mercury concentration in that egg compared to the laboratory-derived thresholds for reproductive impairment, additional information on the mercury levels in other eggs from that nest would be helpful in determining whether harmful levels of mercury were present in the clutch. The measurement of mercury levels in chorioallantoic membranes offers a possible way to estimate how much mercury was in a chick that hatched from an egg, and also in the whole fresh egg itself. While an embryo is developing, wastes are collected in a sac called the chorioallantoic membranes, which often remain inside the eggshell and can be collected for contaminant analysis. We fed methylmercury to captive mallards to generate a broad range of mercury levels in eggs, allowed the eggs to hatch normally, and then compared mercury concentrations in the hatchling versus the chorioallantoic membranes left behind in the eggshell. When the data from eggs laid by mercury- treated females were expressed as common logarithms, a linear equation was created by which the concentration of mercury in a duckling could be predicted from the concentration of mercury in the chorioallantoic membranes from the same egg. Therefore, if it were not possible to collect a sample egg from a clutch of wild bird eggs, the collection of the chorioallantoic membranes could be substituted, and the mercury predicted to be in the chick or whole egg could be compared to the thresholds of mercury that have been shown to cause harm in controlled feeding studies with pheasants, chickens, and mallards.

Heinz, G.H.; Hoffman, D.J.

2003-01-01

232

ATMOSPHERIC MERCURY RESEARCH  

EPA Science Inventory

Environmental contamination from mercury has been recognized for decades as a growing problem to humans and wildlife. It is released from a variety of sources, exhibits a complicated chemistry, and proceeds via several different pathways to humans and wildlife. According to the...

233

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. PMID:5488692

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

1970-01-01

234

Accidental intrathecal mercury application.  

PubMed

The authors present a case of accidental intrathecal mercury application. A 69-year-old white woman was admitted to our department with suspected meningitis following surgery for spinal stenosis at another hospital. Postoperatively, she had developed a cerebro-spinal fluid (CSF) fistula with a subcutaneous cavity. Local wound irritation had been suspected and, unfortunately, mercury-containing disinfectant was injected into the cavity. Within 24 h the patient demonstrated acute neurological deterioration due to meningitis and encephalitis and was admitted to our clinic with suspected meningitis due to postoperative CSF fistula. Lumbar puncture revealed desinfectant-stained, non-bloody CSF, while lumbar MRI demonstrated the large lumbar subcutaneous cavity. Additionally, CSF fistula was visualized on MRI. Laboratory examination revealed extremely high mercury levels in CSF, blood and urine. Treatment consisted in insertion of a lumbar drainage to wash out the mercury. The patient underwent medical detoxication using chelating agents (DMPS: RS-2,3-dimercapto-1-propansulfonacid, DMSA: meso-2,3-dimercaptosuccinatacid). Surgery was performed in order to close the cavity and the fistula. Postoperatively, the patient was admitted to the intensive care unit and remained intubated for 3 days. Within 4 weeks after surgery, she demonstrated good recovery. Eighteen months after intoxication, polyneuropathy and slight neuropsychological deficiencies were detectable. PMID:14586664

Stark, Andreas M; Barth, Harald; Grabner, Jean-Paul; Mehdorn, H Maximilian

2004-05-01

235

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...

236

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 study…

Environmental Research, 1971

1971-01-01

237

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...

238

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,

239

Magnetosphere of Mercury  

NASA Technical Reports Server (NTRS)

A model magnetosphere of Mercury using Mariner 10 data is presented. Diagrams of the bow shock wave and magnetopause are shown. The analysis of Mariner 10 data indicates that the magnetic field of the planet is intrinsic. The magnetic tail and secondary magnetic fields, and the influence of the solar wind are also discussed.

Whang, Y. C.

1975-01-01

240

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 ...

241

MERCURY SPECIATION AND CAPTURE  

EPA Science Inventory

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

242

A mercury transport and fate model (LM2-mercury) for mass budget assessment of mercury cycling in Lake Michigan  

EPA Science Inventory

LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

243

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

244

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...

245

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...

246

A MODELLING FRAMEWORK FOR MERCURY CYCLING IN LAKE MICHIGAN  

EPA Science Inventory

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

247

Small Mercury Relativity Orbiter  

NASA Technical Reports Server (NTRS)

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

Bender, Peter L.; Vincent, Mark A.

1989-01-01

248

Author's personal copy Unusual lithium coordinated platinum and rhodium hydride dimers  

E-print Network

Author's personal copy Unusual lithium coordinated platinum and rhodium hydride dimers Brett D complexes Rhodium complexes Hydride complexes X-ray crystal structures a b s t r a c t Two unusual lithium coordinated binuclear platinum- and rhodium-hydride complexes [M(dip- pe)(H)]2ÁLiHBEt3 were synthesized

Jones, William D.

249

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

250

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

251

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions  

Microsoft Academic Search

Corrosion behavior of nickel hydride is studied in alkaline, neutral, and weakly acidic oxygen-containing solutions by compensating oxygen consumed in corrosion and spectrophotometric analysis of solution for nickel. It is shown that in the course of nickel hydride corrosion in alkaline solutions, oxygen is consumed solely in its interaction with hydrogen formed at hydride decomposition, while nickel remains at the

G. N. Markos’yan; D. S. Sirota; A. P. Pchel’nikov

2005-01-01

252

Investigation of metal hydride materials as hydrogen reservoirs for metal-hydrogen batteries  

NASA Technical Reports Server (NTRS)

The performance and suitability of various metal hydride materials were examined for use as possible hydrogen storage reservoirs for secondary metal-hydrogen batteries. Lanthanum pentanickel hydride appears as a probable candidate in terms of stable hydrogen supply under feasible thermal conditions. A kinetic model describing the decomposition rate data of the hydride has been developed.

ONISCHAK

1976-01-01

253

Opening of a Post Doctoral Position Complex hydrides for hydrogen storage applications  

E-print Network

Opening of a Post Doctoral Position Complex hydrides for hydrogen storage applications on complex hydrides for hydrogen storage applications in connection with the « Fast, reliable and cost effective boron hydride based high capacity solid state hydrogen storage materials» project co

254

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

255

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

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

Involvement of mercury methylation in microbial mercury detoxication  

Microsoft Academic Search

A vitamin B12 requiring strain was isolated fromChlostridium cochlearium T-2 C which is known to synthesize various types of vitamin B12 including methylcobalamin and has an ability to methylate inorganic mercury. The vitamin B12 auxotroph lacking the mercury-methylating activity showed higher sensitivity to inorganic mercury than its original strain, while the sensitivity of both strains to methylmercury was relatively low

Hidemitsu S. Pan-Hou; Nobumasa Imura

1982-01-01

259

AC-impedance studies on metal hydride electrodes  

SciTech Connect

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

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

1994-12-31

260

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

E-print Network

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

Kyle C. Smith; Timothy S. Fisher

2012-05-04

261

Investigation of metal hydride nanoparticles templated in metal organic frameworks.  

SciTech Connect

Hydrogen is proposed as an ideal carrier for storage, transport, and conversion of energy. However, its storage is a key problem in the development of hydrogen economy. Metal hydrides hold promise in effectively storing hydrogen. For this reason, metal hydrides have been the focus of intensive research. The chemical bonds in light metal hydrides are predominantly covalent, polar covalent or ionic. These bonds are often strong, resulting in high thermodynamic stability and low equilibrium hydrogen pressures. In addition, the directionality of the covalent/ionic bonds in these systems leads to large activation barriers for atomic motion, resulting in slow hydrogen sorption kinetics and limited reversibility. One method for enhancing reaction kinetics is to reduce the size of the metal hydrides to nano scale. This method exploits the short diffusion distances and constrained environment that exist in nanoscale hydride materials. In order to reduce the particle size of metal hydrides, mechanical ball milling is widely used. However, microscopic mechanisms responsible for the changes in kinetics resulting from ball milling are still being investigated. The objective of this work is to use metal organic frameworks (MOFs) as templates for the synthesis of nano-scale NaAlH4 particles, to measure the H2 desorption kinetics and thermodynamics, and to determine quantitative differences from corresponding bulk properties. Metal-organic frameworks (MOFs) offer an attractive alternative to traditional scaffolds because their ordered crystalline lattice provides a highly controlled and understandable environment. The present work demonstrates that MOFs are stable hosts for metal hydrides and their reactive precursors and that they can be used as templates to form metal hydride nanoclusters on the scale of their pores (1-2 nm). We find that using the MOF HKUST-1 as template, NaAlH4 nanoclusters as small as 8 formula units can be synthesized inside the pores. A detailed picture of the hydrogen desorption is investigated using a simultaneous thermogravimetric modulated-beam mass spectrometry instrument. The hydrogen desorption behavior of NaAlH4 nano-clusters is found to be very different from bulk NaAlH4. The bulk NaAlH4 desorbs about 70 wt% hydrogen {approx}250 C. In contrast, confinement of NaAlH4 within the MOF pores dramatically increases the rate of H2 desorption at lower temperatures. About {approx}80% of the total H2 desorbed from MOF-confined NaAlH4 is observed between 70 to 155 C. In addition to HKUST-1, we find that other MOFs (e.g. MIL-68 and MOF-5) can be infiltrated with hydrides (LiAlH4, LiBH4) or hydride precursors (Mg(C4H9)2 and LiC2H5) without degradation. By varying pore dimensions, metal centers, and the linkers of MOFs, it will be possible to determine whether the destabilization of metal hydrides is dictated only by the size of the metal hydride clusters, their local environment in a confined space, or by catalytic effects of the framework.

Jacobs, Benjamin W.; Herberg, Julie L. (Lawrence Livermore National Laboratory, Livermore, CA); Highley, Aaron M.; Grossman, Jeffrey (MIT, Cambridge, MA); Wagner, Lucas (MIT, Cambridge, MA); Bhakta, Raghu; Peaslee, D. (University of Missouri, St. Louis, MO); Allendorf, Mark D.; Liu, X. (University of Missouri, St. Louis, MO); Behrens, Richard, Jr.; Majzoub, Eric H. (University of Missouri, St. Louis, MO)

2010-11-01

262

Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.  

SciTech Connect

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

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

2012-02-01

263

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

264

High-Spin Cobalt Hydrides for Catalysis  

SciTech Connect

Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

Holland, Patrick L. [Yale University] [Yale University

2013-08-29

265

Photoelectron spectroscopy of boron aluminum hydride cluster anions  

SciTech Connect

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

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

2014-04-28

266

Ab-initio study of transition metal hydrides  

SciTech Connect

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

Sharma, Ramesh [Dept. of Physics, Feroze Gandhi Insititute of Engineering and Technology, Raebareli-229001 (India); Shukla, Seema, E-mail: sharma.yamini62@gmail.com; Dwivedi, Shalini, E-mail: sharma.yamini62@gmail.com; Sharma, Yamini, E-mail: sharma.yamini62@gmail.com [Theoretical Condensed Matter Physics Laboratory, Dept. of Physics Feroze Gandhi College, Raebareli-229001 (India)

2014-04-24

267

Photoelectron spectroscopy of boron aluminum hydride cluster anions.  

PubMed

Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, BxAlyHz(-), were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms. PMID:24784280

Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K

2014-04-28

268

Photoelectron spectroscopy of boron aluminum hydride cluster anions  

NASA Astrophysics Data System (ADS)

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

Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H.; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K.

2014-04-01

269

Subcutaneous injection of metallic mercury  

Microsoft Academic Search

Deliberate self-injection of metallic mercury into subcutaneous tissue is uncommon. A 41-year-old lady with a history of schizophrenia was admitted to our hospital after deliberate injection of metallic mercury into her right wrist and antecubital fossa. Physical examination was unremarkable except for the injection marks over right antecubital fossa and wrist. The presence of subcutaneous mercury deposits in her right

Y OY Soo; C H Wong; J F Griffith; T YK Chan

2003-01-01

270

Neutrino Factory Mercury Flow Loop  

E-print Network

Neutrino Factory Mercury Flow Loop V. GravesV. Graves C. Caldwell IDS-NF Videoconference March 9, 2010 #12;Flow Loop Review · 1 cm dia nozzle, 20 m/s jet requires 1.57 liter/sec mercury flow (94 2 liter/min 24 9 gpm)mercury flow (94.2 liter/min, 24.9 gpm). · MERIT experiment showed that a pump

McDonald, Kirk

271

[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

2010-01-01

272

Mercury Contamination of Aquatic Ecosystems  

USGS Publications Warehouse

Mercury has been well known as an environmental pollutant for several decades. As early as the 1950's it was established that emissions of mercury to the environment could have serious effects on human health. These early studies demonstrated that fish and other wildlife from various ecosystems commonly attain mercury levels of toxicological concern when directly affected by mercury-containing emissions from human-related activities. Human health concerns arise when fish and wildlife from these ecosystems are consumed by humans. During the past decade, a new trend has emerged with regard to mercury pollution. Investigations initiated in the late 1980's in the northern-tier states of the U.S., Canada, and Nordic countries found that fish, mainly from nutrient-poor lakes and often in very remote areas, commonly have high levels of mercury. More recent fish sampling surveys in other regions of the U.S. have shown widespread mercury contamination in streams, wet-lands, reservoirs, and lakes. To date, 33 states have issued fish consumption advisories because of mercury contamination. These continental to global scale occurrences of mercury contamination cannot be linked to individual emissions of mercury, but instead are due to widespread air pollution. When scientists measure mercury levels in air and surface water, however, the observed levels are extraordinarily low. In fact, scientists have to take extreme precautions to avoid direct contact with water samples or sample containers, to avert sample contamination (Fig 3). Herein lies an apparent discrepancy: Why do fish from some remote areas have elevated mercury concentrations, when contamination levels in the environment are so low?

Krabbenhoft, David P.; Rickert, David A.

1995-01-01

273

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

2013-01-01

274

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

SciTech Connect

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

Harris, Joe P.; Manship, Daniel R.; Wright, Timothy G., E-mail: Tim.Wright@nottingham.ac.uk [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Breckenridge, W. H. [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)

2014-02-28

275

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)

2009-01-20

276

Method for scavenging mercury  

DOEpatents

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

277

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 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 (Bejing, CN); Yan, Naiqiang (Burkeley, CA)

2010-07-13

278

The planet Mercury (1971)  

NASA Technical Reports Server (NTRS)

The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

1972-01-01

279

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

280

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

281

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

282

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

283

Detecting potassium on Mercury  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

284

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

285

Comparison of hydrogen elimination from molecular zinc and magnesium hydride clusters.  

PubMed

In analogy to the previously reported tetranuclear magnesium hydride cluster with a bridged dianionic bis-?-diketiminate ligand, a related zinc hydride cluster has been prepared. The crystal structures of these magnesium and zinc hydride complexes are similar: the metal atoms are situated at the corners of a tetrahedron in which the vertices are bridged either by dianionic bis-?-diketiminate ligands or hydride ions. Both structures are retained in solution and show examples of H(-)???H(-) NMR coupling (Mg: 8.5?Hz; Zn: 16.0?Hz). The zinc hydride cluster [NN-(ZnH)2]2 thermally decomposes at 90?°C and releases 1.8?equivalents of H2 . In contrast to magnesium hydride clusters, there is no apparent relationship between cluster size and thermal decomposition temperature for the zinc hydrides. DFT calculations reproduced the structure of the zinc hydride cluster reasonably well and charge density analysis showed no bond paths between the hydride ions. This contrasts with calculations on the analogous magnesium hydride cluster in which a counter-intuitive H(-)???H(-) bond path was observed. Forcing a reduced H(-)???H(-) distance in the zinc hydride cluster, however, gave rise to a H(-)???H(-) bond path. Such weak interactions could play a role in H2 desorption. The presumed molecular product after H2 release, a Zn(I) cluster, could not be characterized experimentally but DFT calculations predicted a cluster with two localized Zn-Zn bonds. PMID:25066656

Intemann, Julia; Sirsch, Peter; Harder, Sjoerd

2014-08-25

286

The influence of hydride on fracture toughness of recrystallized Zircaloy-4 cladding  

NASA Astrophysics Data System (ADS)

In this work, RXA cladding tubes were hydrogen-charged to target hydrogen content levels between 150 and 800 wppm (part per million by weight). The strings of zirconium hydrides observed in the cross sections are mostly oriented in the circumferential direction. The fracture toughness of hydrided RXA Zircaloy-4 cladding was measured to evaluate its hydride embrittlement susceptibility. With increasing hydrogen content, the fracture toughness of hydrided RXA cladding decreases at both 25 °C and 300 °C. Moreover, highly localized hydrides (forming a hydride rim) aggravate the degradation of the fracture properties of RXA Zircaloy-4 cladding at both 25 °C and 300 °C. Brittle features in the form of quasi-cleavages and secondary cracks were observed on the fracture surface of the hydride rim, even for RXA cladding tested at 300 °C.

Hsu, Hsiao-Hung; Chiang, Ming-Feng; Chen, Yen-Chen

2014-04-01

287

Mercury biotransformations and their potential for remediation of mercury contamination  

Microsoft Academic Search

Bacterially mediated ionic mercury reduction to volatile Hg0 was shown to play an important role in the geochemical cycling of mercury in a contaminated freshwater pond. This process, and the degradation of methylmercury, could be stimulated to reduce the concentration of methylmercury that is available for accumulation by biota. A study testing the utility of this approach is described.

Tamar Barkay; Ralph Turner; Erwan Saouter; Joanne Horn

1992-01-01

288

MERCURY BIOTRANSFORMATIONS AND THEIR POTENTIAL FOR REMEDIATION OF MERCURY CONTAMINATION  

EPA Science Inventory

Bacterially mediated ionic mercury reduction to volatile Hg was shown to play an important role in the geochemical cycling of mercury in a contaminated freshwater pond. his process, and the degradation of methylmercury, could be stimulated to reduce the concentration of methylmer...

289

VOLATILITY OF MERCURY FROM SOILS AMENDED WITH VARIOUS MERCURY COMPOUNDS  

EPA Science Inventory

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

290

Flow injection-chemical vapor generation atomic fluorescence spectrometry hyphenated system for organic mercury determination: A step forward  

NASA Astrophysics Data System (ADS)

Monomethylmercury and ethylmercury were determined on line using flow injection-chemical vapor generation atomic fluorescence spectrometry without neither requiring a pre-treatment with chemical oxidants, nor UV/MW additional post column interface, nor organic solvents, nor complexing agents, such as cysteine. Inorganic mercury, monomethylmercury and ethylmercury were detected by atomic fluorescence spectrometry in an Ar/H 2 miniaturized flame after sodium borohydride reduction to Hg 0, monomethylmercury hydride and ethylmercury hydride, respectively. The effect of mercury complexing agent such as cysteine, ethylendiaminotetracetic acid and HCl with respect to water and Ar/H 2 microflame was investigated. The behavior of inorganic mercury, monomethylmercury and ethylmercury and their cysteine-complexes was also studied by continuous flow-chemical vapor generation atomic fluorescence spectrometry in order to characterize the reduction reaction with tetrahydroborate. When complexed with cysteine, inorganic mercury, monomethylmercury and ethylmercury cannot be separately quantified varying tetrahydroborate concentration due to a lack of selectivity, and their speciation requires a pre-separation stage (e.g. a chromatographic separation). If not complexed with cysteine, monomethylmercury and ethylmercury cannot be separated, as well, but their sum can be quantified separately with respect to inorganic mercury choosing a suitable concentration of tetrahydroborate (e.g. 10 - 5 mol L - 1 ), thus allowing the organic/inorganic mercury speciation. The detection limits of the flow injection-chemical vapor generation atomic fluorescence spectrometry method were about 45 nmol L - 1 (as mercury) for all the species considered, a relative standard deviation ranging between 1.8 and 2.9% and a linear dynamic range between 0.1 and 5 ?mol L - 1 were obtained. Recoveries of monomethylmercury and ethylmercury with respect to inorganic mercury were never less than 91%. Flow injection-chemical vapor generation atomic fluorescence spectrometry method was validated by analyzing the TORT-1 certificate reference material, which contains only monomethylmercury, and obtaining 83 ± 5% of monomethylmercury recovered, respectively. This method was also applied to the determination of monomethylmercury in saliva samples.

Angeli, Valeria; Biagi, Simona; Ghimenti, Silvia; Onor, Massimo; D'Ulivo, Alessandro; Bramanti, Emilia

2011-11-01

291

Structure Properties of Ternary Hydrides Ni3AlHx  

NASA Astrophysics Data System (ADS)

The structure properties of the ternary hydrides Ni3AlHx are studied by use of the interatomic pair potentials obtained from the first principles electronic structure calculation and Chen-Mobius 3-dimensional lattice inversion method. The heat of formation and volume expansion of the hydrogenized systems are investigated.

Pan, Yi-wei; Zhang, Wen-qing; Chen, Nan-xian

1996-09-01

292

Generation of hydrogen isotopes with an electricpulse hydride injector  

Microsoft Academic Search

An Electric Pulse Hydride Injector (EPHI) designed for safe interim tritium storagehas been developed for the dosed supply of hydrogen isotopes in a time interval ranging fromseveral milliseconds up to hundreds of seconds. The release of gas occurs via current pulsesthrough the active elements of the EPHI, each of which is made of a thin molybdenum foil coatedon both sides

I. s Glushkov; Yu. A Kareev; Yu. V Petrov; A. n Savotkin; V. V Frunze; E Hutter; G Müller; R.-D Penzhorn; U Tamm

1999-01-01

293

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

294

Sites and Diffusion of Muons in Fcc Metal Hydride Systems.  

NASA Astrophysics Data System (ADS)

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

Kempton, James Russell

1987-09-01

295

RMP Mercury Strategy 06-03-09.doc Page 1 of 5 RMP MERCURY STRATEGY  

E-print Network

RMP Mercury Strategy 06-03-09.doc Page 1 of 5 RMP MERCURY STRATEGY Mercury is a pollutant of high the information most urgently needed by managers to find remedies to the Bay's mercury problem. The focus of total mercury in the Bay are expected to slowly decline over coming decades. The premise

296

Mercury Content of Illinois Soils  

Microsoft Academic Search

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ± 20 µg\\/kg soil, and the background content

G. B. Dreher; L. R. Follmer

2004-01-01

297

Bioaccumulation of Mercury in Sharks  

E-print Network

Bioaccumulation of Mercury in Sharks Part 2 a Using a subset of data collected on RJD shark research trips, you will analyze the mercury levels found in the Florida Sharks we catch. Based on your, and hypothesize why that might be. You will also be able to determine whether eating shark is a risk to human

Miami, University of

298

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

299

The magnetic field of Mercury  

Microsoft Academic Search

The magnetic field of Mercury was measured on two fly-bys of the planet by the Mariner 10 space-craft. The presence of a field at Mercury is interesting for what it implies for both the internal and external sources of field. The internal field of the planet is almost certainly generated by an internal dynamo although there remain many puzzles as

D. J. Southwood

1997-01-01

300

The magnetic field of Mercury  

Microsoft Academic Search

The magnetic field of Mercury was measured on two fly-bys of the planet by the Mariner 10 spacecraft. The presence of a field at Mercury is interesting for what it implies for both the internal and external sources of field. The internal field of the planet is almost certainly generated by an internal dynamo although there remain many puzzles as

D. J. Southwood

1997-01-01

301

Mercury in Canadian prairie ducks  

Microsoft Academic Search

Tissues of 190 ducks, shot on the Canadian prairie during the hunting seasons of 1969 and 1970, were analyzed for mercury residues. Residue levels of over 0.5 ppm were found only in breast muscle of common mergansers (Mergus merganser). Livers contained, on the average, 2.9 times as much mercury as breast muscles. Primary feathers contained, on the average, 12 times

K. Vermeer; F. A. J. Armstrong

1972-01-01

302

Stanford University Mercury Thermometer Replacement  

E-print Network

Stanford University Mercury Thermometer Replacement Program Instructions for Reuniting Separated Fluid Column of Non-Mercury Thermometer Heating Method Heat the thermometers bulb in an upright position of the thermometer. Note that over filling the expansion chamber will break the thermometer. Tap the thermometer

303

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

304

Mercury Speciation in the Presence of Polysulfides  

E-print Network

Mercury Speciation in the Presence of Polysulfides J E N N Y A Y L A J A Y , * , F R A N C¸ O I Environmental mercury methylation appears modulated by sulfide concentrations, possibly via changes in mercury, there has been much recent interest in quantifying the chemical speciation and lipid solubility of mercury

Morel, François M. M.

305

Mercury Pollution in the Marine Environment  

E-print Network

Mercury Pollution in the Marine Environment The Coastal and Marine Mercury Ecosystem Research stakeholders to form C-MERC, the Coastal and Marine Mercury Ecosystem Research Collaborative. The goal was to review current knowledge--and knowledge gaps--relating to a global environmental health problem, mercury

Shepherd, Simon

306

Mercury Spill Information and Response Guidance  

E-print Network

Mercury Spill Information and Response Guidance Background Information Mercury can be found, plumbing traps and vacuum pumps. When mercury is spilled, it forms beads or droplets that can accumulate mercury vapors can be very dangerous, depending on the amount inhaled and the length of exposure

Holland, Jeffrey

307

Mercury and the Gold Country Angler Survey  

E-print Network

#12;#12;Mercury and the Gold Rush #12;#12;#12;#12;#12;#12;#12;#12;#12;Gold Country Angler Survey A Pilot Study to Assess Mercury Exposure from Sport Fish Consumption in the Sierra Nevada Carrie Monohan, Ph.D. #12;Mercury and the Gold Rush Deer Creek 1908 Greenhorn Creek 2011 Mercury was used during

308

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

309

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.

310

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

311

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

312

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

313

Mercury emissions from geothermal power plants.  

PubMed

Geothermal steam used for power production contains significant quantities of volatile mercury. Much of this mercury escapes to the atmosphere as elemental mercury vapor in cooling tower exhausts. Mercury emissions from geothermal power plants, on a per megawatt (electric) basis, are comparable to releases from coal-fired power plants. PMID:860131

Robertson, D E; Crecelius, E A; Fruchter, J S; Ludwick, J D

1977-06-01

314

Mercury emissions from geothermal power plants  

Microsoft Academic Search

Geothermal steam used for power production contains significant quantities of volatile mercury. Much of this mercury escapes to the atmosphere as elemental mercury vapor in cooling tower exhausts. Mercury emissions from geothermal power plants, on a per megawatt (electric) basis, are comparable to releases from coal-fired power plants.

D. E. Robertson; E. A. Crecelius; J. S. Fruchter; J. D. Ludwick

1977-01-01

315

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

316

Mercury accumulation and loss in mallard eggs  

USGS Publications Warehouse

Female mallards (Anas platyrhynchos) were fed diets containing 5, 10, or 20 ppm mercury as methylmercury chloride. One egg was collected from each bird before the start of the mercury diets and 15 eggs were collected from each bird while it was being fed mercury. The mercury diets were then replaced by uncontaminated diets, and each female was allowed to lay 29 more eggs. Mercury levels in eggs rose to about 7,18, and 35 ppm wet-weight in females fed 5,10, or 20 ppm mercury, respectively. Mercury levels fell to about 0.16,0.80, and 1.7 ppm in the last egg laid by birds that had earlier been fed 5, 10, or 20 ppm mercury, respectively. Higher concentrations of mercury were found in egg albumen than in yolk, and between 95 and 100% of the mercury in the eggs was in the form of methylmercury.

Heinz, G.H.; Hoffman, D.J.

2004-01-01

317

Efficient catalysis by MgCl2 in hydrogen generation via hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis.  

PubMed

Magnesium chloride efficiently catalyzed the hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis. Hydrogen yield of 1635 mL g(-1) was obtained (MgH(2)), i.e. with 96% conversion in 30 min at 303 K. PMID:22538836

Zhao, Zelun; Zhu, Yunfeng; Li, Liquan

2012-06-01

318

Geothermal hazards - Mercury emission  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

319

Reference Atmosphere for Mercury  

NASA Technical Reports Server (NTRS)

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

Killen, Rosemary M.

2002-01-01

320

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

321

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

322

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

323

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

324

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

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 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...

2010-10-01

325

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

Code of Federal Regulations, 2014 CFR

... 2014-10-01 2014-10-01 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...

2014-10-01

326

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

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 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...

2013-10-01

327

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...

328

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

329

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

DOEpatents

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

Broderick, Thomas E.

2005-09-13

330

Mercury toxicity and neurodegenerative effects.  

PubMed

Mercury is among the most toxic heavy metals and has no known physiological role in humans. Three forms of mercury exist: elemental, inorganic and organic. Mercury has been used by man since ancient times. Among the earliest were the Chinese and Romans, who employed cinnabar (mercury sulfide) as a red dye in ink (Clarkson et al. 2007). Mercury has also been used to purify gold and silver minerals by forming amalgams. This is a hazardous practice, but is still widespread in Brazil's Amazon basin, in Laos and in Venezuela, where tens of thousands of miners are engaged in local mining activities to find and purify gold or silver. Mercury compounds were long used to treat syphilis and the element is still used as an antiseptic,as a medicinal preservative and as a fungicide. Dental amalgams, which contain about 50% mercury, have been used to repair dental caries in the U.S. since 1856.Mercury still exists in many common household products around the world.Examples are: thermometers, barometers, batteries, and light bulbs (Swain et al.2007). In small amounts, some organo mercury-compounds (e.g., ethylmercury tiosalicylate(thimerosal) and phenylmercury nitrate) are used as preservatives in some medicines and vaccines (Ballet al. 2001).Each mercury form has its own toxicity profile. Exposure to Hg0 vapor and MeHg produce symptoms in CNS, whereas, the kidney is the target organ when exposures to the mono- and di-valent salts of mercury (Hg+ and Hg++, respectively)occur. Chronic exposure to inorganic mercury produces stomatitis, erethism and tremors. Chronic MeHg exposure induced symptoms similar to those observed in ALS, such as the early onset of hind limb weakness (Johnson and Atchison 2009).Among the organic mercury compounds, MeHg is the most biologically available and toxic (Scheuhammer et a!. 2007). MeHg is neurotoxic, reaching high levels of accumulation in the CNS; it can impair physiological function by disrupting endocrine glands (Tan et a!. 2009).The most important mechanism by which mercury causes toxicity appears to bemitochondrial damage via depletion of GSH (Nicole et a!. 1998), coupled with binding to thiol groups ( -SH), which generates free radicals. Mercury has a high affinity for thiol groups ( -SH) and seleno groups ( -SeH) that are present in amino acids as cysteine and N-acetyl cysteine, lipoic acid, proteins, and enzymes. N-acetylcysteine and cysteine are precursors for the biosynthesis of GSH, which is among the most powerful intracellular antioxidants available to protect against oxidative stress and inflammation.Mercury and methylmercury induce mitochondrial dysfunction, which reduces ATP synthesis and increases lipid, protein and DNA peroxidation. The content of metallothioneines, GSH, selenium and fish high in omega-3 fatty acids appear to be strongly related with degree of inorganic and organic mercury toxicity, and with the protective detoxifying mechanisms in humans. In conclusion, depletion of GSH,breakage of mitochondria, increased lipid peroxidation, and oxidation of proteins and DNA in the brain, induced by mercury and his salts, appear to be important factors in conditions such as ALS and AD (Bains and Shaw 1997; Nicole eta!. 1998;Spencer eta!. 1998; Alberti et a!. 1999). PMID:24515807

Carocci, Alessia; Rovito, Nicola; Sinicropi, Maria Stefania; Genchi, Giuseppe

2014-01-01

331

Volcanic mercury in Pinus canariensis  

NASA Astrophysics Data System (ADS)

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 ?g kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 ?g kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 ?g kg-1) and bark (6.0 ?g kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

2013-08-01

332

Mercury content of Illinois soils  

USGS Publications Warehouse

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

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

2004-01-01

333

Volcanic mercury in Pinus canariensis.  

PubMed

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 ?g kg(-1)) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 ?g kg(-1)). Thus, mercury emissions originating from the eruption remained only as a mark-in pyroclastic wounds-and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 ?g kg(-1)) and bark (6.0 ?g kg(-1)) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species. PMID:23760570

Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

2013-08-01

334

Atmospheric mercury footprints of nations.  

PubMed

The Minamata Convention was established to protect humans and the natural environment from the adverse effects of mercury emissions. A cogent assessment of mercury emissions is required to help implement the Minamata Convention. Here, we use an environmentally extended multi-regional input-output model to calculate atmospheric mercury footprints of nations based on upstream production (meaning direct emissions from the production activities of a nation), downstream production (meaning both direct and indirect emissions caused by the production activities of a nation), and consumption (meaning both direct and indirect emissions caused by final consumption of goods and services in a nation). Results show that nations function differently within global supply chains. Developed nations usually have larger consumption-based emissions than up- and downstream production-based emissions. India, South Korea, and Taiwan have larger downstream production-based emissions than their upstream production- and consumption-based emissions. Developed nations (e.g., United States, Japan, and Germany) are in part responsible for mercury emissions of developing nations (e.g., China, India, and Indonesia). Our findings indicate that global mercury abatement should focus on multiple stages of global supply chains. We propose three initiatives for global mercury abatement, comprising the establishment of mercury control technologies of upstream producers, productivity improvement of downstream producers, and behavior optimization of final consumers. PMID:25723898

Liang, Sai; Wang, Yafei; Cinnirella, Sergio; Pirrone, Nicola

2015-03-17

335

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

336

Distribution of total mercury and methyl mercury in water, sediment, and fish from South Florida estuaries  

USGS Publications Warehouse

Concentrations of total mercury and methyl mercury were determined in sediment and fish collected from estuarine waters of Florida to understand their distribution and partitioning. Total mercury concentrations in sediments ranged from 1 to 219 ng/g dry wt. Methyl mercury accounted for, on average, 0.77% of total mercury in sediment. Methyl mercury concentrations were not correlated with total mercury or organic carbon content in sediments. The concentrations of total mercury in fish muscle were between 0.03 and 2.22 (mean: 0.31) ??g/g, wet wt, with methyl mercury contributing 83% of total mercury. Methyl mercury concentrations in fish muscle were directly proportional to total mercury concentrations. The relationship of total and methyl mercury concentrations in fish to those of sediments from corresponding locations was fish-species dependent, in addition to several abiotic factors. Among fish species analyzed, hardhead catfish, gafftopsail catfish, and sand seatrout contained the highest concentrations of mercury. Filtered water samples from canals and creeks that discharge into the Florida Bay showed mercury concentrations of 3-7.4 ng/L, with methyl mercury accounting for <0.03-52% of the total mercury. Consumption of fish containing 0.31 ??g mercury/g wet wt, the mean concentration found in this study, at rates greater than 70 g/day, was estimated to be hazardous to human health.

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

1998-01-01

337

An automated hydride generation-cryogenic trapping-ICP-MS system for measuring inorganic and methylated Ge, Sb and As species  

E-print Network

hydride generation, cryogenic trapping and inductively coupled plasma mass spectrometry (ICP-MS) can and raise the hydride trap into and out of a liquid nitrogen dewar and to control the heating of the hydride

Canberra, University of

338

SPECIATION OF ARSENIC COMPOUNDS IN DRINKING WATER BY CAPILLARY ELECTROPHORESIS WITH HYDRODYNAMICALLY MODIFIED ELECTROOSMOTIC FLOW DETECTED THROUGH HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS...  

EPA Science Inventory

Capillary electrophoresis (CE) was used to speciate four environmentally significant, toxic forms of arsenic: arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid. Hydride generation (HG) was used to convert the species into their respective hydrides. The hydride s...

339

SPECIATION OF ARSENIC COMPOUNDS IN DRINKING WATER BY CAPILLARY ELECTROPHORESIS WITH HYDRODYNAMICALLY MODIFIED ELECTROOSMOTIC FLOW DETECTED THROUGH HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS..  

EPA Science Inventory

Capillary electrophoresis (CE) was used to speciate four environmentally significant, toxic forms of arsenic: arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid. Hydride generation (HG) was used to convert the species into their respective hydrides. The hydride ...

340

Effect of thermo-mechanical cycling on zirconium hydride reorientation studied in situ with synchrotron X-ray diffraction  

NASA Astrophysics Data System (ADS)

The circumferential hydrides normally present in nuclear reactor fuel cladding after reactor exposure may dissolve during drying for dry storage and re-precipitate when cooled under load into a more radial orientation, which could embrittle the fuel cladding. It is necessary to study the rates and conditions under which hydride reorientation may happen in order to assess fuel integrity in dry storage. The objective of this work is to study the effect of applied stress and thermal cycling on the hydride morphology in cold-worked stress-relieved Zircaloy-4 by combining conventional metallography and in situ X-ray diffraction techniques. Metallography is used to study the evolution of hydride morphology after several thermo-mechanical cycles. In situ X-ray diffraction performed at the Advanced Photon Source synchrotron provides real-time information on the process of hydride dissolution and precipitation under stress during several thermal cycles. The detailed study of diffracted intensity, peak position and full-width at half-maximum provides information on precipitation kinetics, elastic strains and other characteristics of the hydride precipitation process. The results show that thermo-mechanical cycling significantly increases the radial hydride fraction as well as the hydride length and connectivity. The radial hydrides are observed to precipitate at a lower temperature than circumferential hydrides. Variations in the magnitude and range of hydride strains due to reorientation and cycling have also been observed. These results are discussed in light of existing models and experiments on hydride reorientation. The study of hydride elastic strains during precipitation shows marked differences between circumferential and radial hydrides, which can be used to investigate the reorientation process. Cycling under stress above the threshold stress for reorientation drastically increases both the reoriented hydride fraction and the hydride size. The reoriented hydride fraction decreases with increasing hydrogen content although the radial hydride content remains constant (for levels above 200 wt.ppm). The precipitation of reoriented hydrides under stress above the threshold stress for reorientation occurs at a lower temperature than the precipitation of in-plane (circumferential) hydrides in unstressed samples. The effects of cycling on the precipitation temperature when precipitating reoriented hydrides are small. When radial hydrides precipitate under stress, during the first precipitation stage at high temperature the hydride strains become tensile in the direction perpendicular to the hydride platelet face. During the second precipitation regime, these strains remain constant in tension. This indicates a different hydride strain state for reoriented hydrides than for circumferential hydrides. The magnitude of the tensile hydride strain in the transverse direction as measured by the change in d-spacing in the reoriented hydride face increases with cycling, potentially because of the increasing reoriented hydride fraction. The analysis of the FWHM confirms the observed 'signature' of hydride reorientation in a mixed population of hydrides as previously observed in the literature. Once the hydride population is fully reoriented, the FWHM decreases due to the fact that a single population of reoriented hydrides is now present. The strain distribution in this single population is smaller than for a mixed population of circumferential and reoriented hydrides.

Colas, Kimberly B.; Motta, Arthur T.; Daymond, Mark R.; Almer, Jonathan D.

2013-09-01

341

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

342

The free-energy barrier to hydride transfer across a dipalladium complex.  

PubMed

We use density-functional theory molecular dynamics (DFT-MD) simulations to determine the hydride transfer coordinate between palladium centres of the crystallographically observed terminal hydride locations, Pd-Pd-H, originally postulated for the solution dynamics of the complex bis-NHC dipalladium hydride [{(MesIm)2CH2}2Pd2H][PF6], and then calculate the free-energy along this coordinate. We estimate the transfer barrier-height to be about 20 kcal mol(-1) with a hydride transfer rate in the order of seconds at room temperature. We validate our DFT-MD modelling using inelastic neutron scattering which reveals anharmonicity of the hydride environment that is so pronounced that there is complete failure of the harmonic model for the hydride ligand. The simulations are extended to high temperature to bring the H-transfer to a rate that is accessible to the simulation technique. PMID:25652724

Vanston, C R; Kearley, G J; Edwards, A J; Darwish, T A; de Souza, N R; Ramirez-Cuesta, A J; Gardiner, M G

2015-01-01

343

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 ...

344

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

345

DIETARY METHYL MERCURY EXPOSURE IN AMERICAN KESTRELS; PILOT STUDY  

EPA Science Inventory

Anthropogenic mercury emissions have increased atmospheric mercury levels about threefold since the advent of industrial activity. Atmospheric deposition is the primary source of mercury in the environment hence mercury contamination has increased in similar fashion. Methyl mercu...

346

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

347

Preparation of hydride complexes of ruthenium with bidentate phosphite ligands  

Microsoft Academic Search

Hydride complex RuH2(PFFP)2 (1) [PFFP=(CF3CH2O)2PN(CH3)N(CH3)P(OCH2CF3)2] was prepared by allowing the compound RuCl4(bpy)·H2O (bpy=1,2-bipyridine) to react first with the phosphite PFFP and then with NaBH4. Chloro-complex RuCl2(PFFP)2 (2) was also prepared, either by reacting RuCl4(bpy)·H2O with PFFP and zinc dust or by substituting triphenylphosphine with PFFP in the precursor complex RuCl2(PPh3)3. Hydride derivative RuH2(POOP)2 (3) (POOP=Ph2POCH2CH2OPPh2) was prepared by reacting compound

Jorge Bravo; Jesús Castro; Soledad García-Fontán; Ma Carmen Rodríguez-Martínez; Gabriele Albertin; Stefano Antoniutti; Alessandro Manera

2007-01-01

348

Metal Hydride/Chemical Heat Pump Development Project  

NASA Astrophysics Data System (ADS)

The metal hydride heat pump (MMHP) is a chemical heat pump containing two hydrides for the storage and/or recovery of thermal energy. It utilizes the heat of reaction of hydrogen with specific metal alloys. The MMHP design can be tailored to provide heating and/or cooling over a wide range of input and ambient temperatures. This system can thus be used with a variety of heat sources including industrial waste heat, solar energy or even a fossil fuel. Applications and market sectors, conceptual development, thermal and mechanical design, laboratory verification of design and material performance, cost analysis and the design, fabrication and testing of an Engineering Development Test Unit (EDTU) are included within the scope of the program.

Cunningham, S. J.

1982-03-01

349

ALUMINUM HYDRIDE: A REVERSIBLE STORAGE MATERIAL FOR HYDROGEN STORAGE  

SciTech Connect

One of the challenges of implementing the hydrogen economy is finding a suitable solid H{sub 2} storage material. Aluminium (alane, AlH{sub 3}) hydride has been examined as a potential hydrogen storage material because of its high weight capacity, low discharge temperature, and volumetric density. Recycling the dehydride material has however precluded AlH{sub 3} from being implemented due to the large pressures required (>10{sup 5} bar H{sub 2} at 25 C) and the thermodynamic expense of chemical synthesis. A reversible cycle to form alane electrochemically using NaAlH{sub 4} in THF been successfully demonstrated. Alane is isolated as the triethylamine (TEA) adduct and converted to unsolvated alane by heating under vacuum. To complete the cycle, the starting alanate can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride (NaH) This novel reversible cycle opens the door for alane to fuel the hydrogen economy.

Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B; Joshua Gray, J

2009-01-09

350

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

351

Reversible metal-hydride phase transformation in epitaxial films.  

PubMed

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

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

2015-03-11

352

Reversible metal–hydride phase transformation in epitaxial films  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

353

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

354

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

PubMed

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

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

2009-03-20

355

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. PMID:19333448

Felderhoff, Michael; Bogdanovi?, Borislav

2009-01-01

356

Determination of trace bismuth by flow injection-hydride generation collection-atomic absorption spectrometry  

Microsoft Academic Search

Bismuth hydride gas was collected on-line and determined via a new flow injection-hydride generation collection-flame atomic absorption spectrometry system. The performance of the gas-liquid separator, hydride gas collection time, acidity of the sample solution, NaBH4 concentration, and the effects of concomitant interferents were investigated to optimize the conditions of this new method. Interferences from concomitant elements were investigated, and recoveries

Shu Yu Chen; Zhi Feng Zhang; Hua Ming Yu

2002-01-01

357

Neutral binuclear rare-earth metal complexes with four ?2-bridging hydrides.  

PubMed

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

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

2015-03-10

358

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

359

[The gaseous phase enrichment techniques in hydride generation (review)].  

PubMed

The gaseous phase of hydride enrichment techniques have been systematically described in this paper. These enrichment techniques including liquid nitrogen trap, balloon collection, in situ pre-concentration in pre-heated graphite furnace, trapped in absorbing solutions, and in some absorbing solid substances. The principle and the application of these techniques have been discussed detail too. The near future trends of the techniques have reviewed also. PMID:12945368

Guo, X; Guo, X; Huang, B

2000-08-01

360

Mechanisms of hydrogen induced delayed cracking in hydride forming materials  

Microsoft Academic Search

Mechanisms which have been formulated to describe delayed hydrogen cracking in hydride-forming metals are reviewed and discussed.\\u000a Particular emphasis is placed on the commercial alloy Zr-2.5 pct Nb (Cb) which is extensively used in nuclear reactor core\\u000a components. A quantitative model for hydrogen cracking in this material is presented and compared with available experimental\\u000a data. The kinetics of crack propagation

R. Dutton; K. Nuttall; M. P. Puls; L. A. Simpson

1977-01-01

361

Fiber optic hydrogen detectors containing Mg-based metal hydrides  

Microsoft Academic Search

We report on the implementation of Pd-capped chemo-chromic metal hydrides as a sensing layer in fiber optic hydrogen detectors. Due to the change in optical properties of Mg-based alloys on hydrogen absorption, a drop in reflectance by a factor of 10 is demonstrated at hydrogen levels down to 15% of the lower explosion limit. The switching takes place in only

M. J. Slaman; B. Dam; M. Pasturel; D. M. Borsa; H. Schreuders; J. H. Rector; R. P. Griessen

2007-01-01

362

Ground-state energy and relativistic corrections for positronium hydride  

SciTech Connect

Variational calculations of the ground state of positronium hydride (HPs) are reported, including various expectation values, electron-positron annihilation rates, and leading relativistic corrections to the total and dissociation energies. The calculations have been performed using a basis set of 4000 thoroughly optimized explicitly correlated Gaussian basis functions. The relative accuracy of the variational energy upper bound is estimated to be of the order of 2x10{sup -10}, which is a significant improvement over previous nonrelativistic results.

Bubin, Sergiy; Varga, Kalman [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2011-07-15

363

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

364

Hydride Compressor Sorption Cooler and Surface Contamination Issues  

Microsoft Academic Search

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

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

2003-01-01

365

Hydride Compressor Sorption Cooler and Surface Contamination Issues  

Microsoft Academic Search

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

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

2003-01-01

366

Hydride Compressor Sorption Cooler and Surface Contamination Issues  

Microsoft Academic Search

A continuous-duty hydrogen sorption cryocooler is being developed for the Planck spacecraft, a mission to map the cosmic microwave background beginning in 2007. Thii cryocooler uses six individual compressor elements (CEs) filled with the hydriding alloy LaNi4.,8Sno.~ to provide high- pressure (50 bar) hydrogen to a Joule-Thomson (J-T) expander and to absorb low-pressure (43 bar) gas fiom liquid hydrogen reservoirs

R. C. Bowman; J. W. Reitert; M. Prina; J. G. Kdleck; W. A. WordT

367

Electrolytic hydriding of TiFe 50\\/50 alloy  

Microsoft Academic Search

The electrolytic insertion of hydrogen into different samples of the intermetallic compound (IMC) TiFe 50\\/50 was investigated by voltammetry and galvanostatic charging–discharging cycles in order to devise conditions which would lead to extensive hydriding. The voltammetric pattern achieved in aqueous KOH shows both reduction and oxidation peaks well positive to the hydrogen evolution reaction. Such a pattern can hardly be

M. Bernardini; N. Comisso; G. Davolio; G. Mengoli

2000-01-01

368

Thermomechanics of hydrogen storage in metallic hydrides: modeling and analysis  

E-print Network

A thermodynamically consistent mathematical model for hydrogen adsorption in metal hydrides is proposed. Beside hydrogen diffusion, the model accounts for phase transformation accompanied by hysteresis, swelling, temperature and heat transfer, strain, and stress. We prove existence of solutions of the ensuing system of partial differential equations by a carefully-designed, semi-implicit approximation scheme. A generalization for a drift-diffusion of multi-component ionized "gas" is outlined, too.

Tomas Roubicek; Giuseppe Tomassetti

2013-09-12

369

Scanning electron microscope techniques for studying Zircaloy corrosion and hydriding  

SciTech Connect

A procedure has been developed for preparing scanning electron microscope (SEM) samples of irradiated or unirradiated Zircaloy, suitable for oxide layer imaging, hydride concentration and morphology determination, and X-ray microanalysis (EPMA). The area fraction of the hydride phase is determined by image analysis of backscattered electron images (BEI). Measurements performed on unirradiated laboratory-hydrided samples, as well as cladding samples from pressurized water reactor (PWR) fuel irradiated to a burnup of about 40 MWd/kg U, gave good agreement with hot extraction hydrogen analysis over a wide range of hydrogen concentrations, based on the assumption that all the hydrogen i present as the {delta}-phase hydride. The local hydrogen concentration can be determined quantitatively with a spatial resolution of less than 100{mu}m. This capability was used to determine the radial hydrogen concentration profiles across the cladding wall for PWR samples with different total hydrogen contents, surface oxide thicknesses, and local heat rating. The results indicated that the hydrogen concentration profile was essentially flat (uniform) across the wall thickness for the samples with a low total hydrogen content ({approx}200 ppm) or a negligible radial heat flux (plenum), while the samples from fueled sections with >200 ppm or a negligible radial heat flux (plenum), while the samples from fueled sections with >200 ppm H had a steep increase in the hydrogen concentration close to the outer surface. Analysis of a longitudinal section showed peak hydrogen concentrations opposite pellet interfaces a factor of two higher than in the mid-pellet region.

Schrire, D.I. [ABB Atom AB, Vaesteraas (Sweden); Pearce, J.H. [AEA Technology, Windscale (United Kingdom)

1994-12-31

370

Nickel metal hydride batteries for high power applications  

Microsoft Academic Search

Nickel metal hydride (Ni\\/MH) is presently the most promising battery system for electric and hybrid vehicle propulsion in the short and mid-term. This paper presents the results obtained in the development of prismatic Ni\\/MH batteries for high power, mainly hybrid vehicle, applications.Valve regulated Ni\\/MH cells rated at 25 and 60Ah have been designed and assembled using improved positive and negative

M. Luisa Soria; Joaqu??n Chacón; J. Carlos Hernández; Daniel Moreno; Araceli Ojeda

2001-01-01

371

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. PMID:20816346

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

2011-01-01

372

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

373

Uranium metal reactions with hydrogen and water vapour and the reactivity of the uranium hydride produced  

SciTech Connect

Within the nuclear industry, metallic uranium has been used as a fuel. If this metal is stored in a hydrogen rich environment then the uranium metal can react with the hydrogen to form uranium hydride which can be pyrophoric when exposed to air. The UK National Nuclear Laboratory has been carrying out a programme of research for Sellafield Limited to investigate the conditions required for the formation and persistence of uranium hydride and the reactivity of the material formed. The experimental results presented here have described new results characterising uranium hydride formed from bulk uranium at 50 and 160 C. degrees and measurements of the hydrolysis kinetics of these materials in liquid water. It has been shown that there is an increase in the proportion of alpha-uranium hydride in material formed at lower temperatures and that there is an increase in the rate of reaction with water of uranium hydride formed at lower temperatures. This may at least in part be attributable to a difference in the reaction rate between alpha and beta-uranium hydride. A striking observation is the strong dependence of the hydrolysis reaction rate on the temperature of preparation of the uranium hydride. For example, the reaction rate of uranium hydride prepared at 50 C. degrees was over ten times higher than that prepared at 160 C. degrees at 20% extent of reaction. The decrease in reaction rate with the extent of reaction also depended on the temperature of uranium hydride preparation.

Godfrey, H. [National Nuclear Laboratory, Workington Laboratory, Havelock Road, Derwent Howe, Cumbria, CA14 3YQ (United Kingdom); Broan, C.; Goddard, D.; Hodge, N.; Woodhouse, G. [National Nuclear Laboratory, Preston Laboratory, Springfields, Salwick, Preston, Lancashire, PR4 0XJ (United Kingdom); Diggle, A. [Sellafield Limited, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom); Orr, R. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

2013-07-01

374

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

375

Investigation of long term stability in metal hydrides  

NASA Technical Reports Server (NTRS)

It is apparent from the literature and the results of this study that cyclic degradation of AB(5) type metal hydrides varies widely according to the details of how the specimens are cycled. The Rapid Cycle Apparatus (RCA) used produced less degradation in 5000 to 10000 cycles than earlier work with a Slow Cycle Apparatus (SCA) produced in 1500 cycles. Evidence is presented that the 453 K (356 F) Thermal Aging (TA) time spent in the saturated condition causes hydride degradation. But increasing the cooling (saturation) period in the RCA did not greatly increase the rate of degradation. It appears that TA type degradation is secondary at low temperatures to another degradation mechanism. If rapid cycles are less damaging than slow cycles when the saturation time is equal, the rate of hydriding/dehydriding may be an important factor. The peak temperatures in the RCA were about 30 C lower than the SCA. The difference in peak cycle temperatures (125 C in the SCA, 95 C in RCA) cannot explain the differences in degradation. TA type degradation is similar to cyclic degradation in that nickel peaks and line broadening are observed in X ray diffraction patterns after either form of degradation.

Marmaro, Roger W.; Lynch, Franklin E.; Chandra, Dhanesh; Lambert, Steve; Sharma, Archana

1991-01-01

376

Diffusional exchange of isotopes in a metal hydride sphere.  

SciTech Connect

This report describes the Spherical Particle Exchange Model (SPEM), which simulates exchange of one hydrogen isotope by another hydrogen isotope in a spherical metal hydride particle. This is one of the fundamental physical processes during isotope exchange in a bed of spherical metal particles and is thus one of the key components in any comprehensive physics-based model of exchange. There are two important physical processes in the model. One is the entropy of mixing between the two isotopes; the entropy of mixing is increased by having both isotopes randomly placed at interstitial sites on the lattice and thus impedes the exchange process. The other physical process is the elastic interaction between isotope atoms on the lattice. The elastic interaction is the cause for {beta}-phase formation and is independent of the isotope species. In this report the coupled diffusion equations for two isotopes in the {beta}-phase hydride are solved. A key concept is that the diffusion of one isotope depends not only on its concentration gradient, but also on the concentration gradient of the other isotope. Diffusion rate constants and the chemical potentials for deuterium and hydrogen in the {beta}-phase hydride are reviewed because these quantities are essential for an accurate model of the diffusion process. Finally, a summary of some of the predictions from the SPEM model are provided.

Wolfer, Wilhelm G.; Hamilton, John C.; James, Scott Carlton

2011-04-01

377

The Reactivity Patterns of Low-Coordinate Iron Hydride Complexes  

PubMed Central

We report a survey of the reactivity of the first isolable iron-hydride complexes with a coordination number less than five. The high-spin iron(II) complexes [(?-diketiminate)Fe(?-H)]2 react rapidly with representative cyanide, isocyanide, alkyne, N2, alkene, diazene, azide, CO2, carbodiimide and Brønsted acid containing substrates. The reaction outcomes fall into three categories: (1) addition of Fe-H across a multiple bond of the substrate, (2) reductive elimination of H2 to form iron(I) products, and (3) protonation of the hydride to form iron(II) products. The products include imide, isocyanide, vinyl, alkyl, azide, triazenido, benzo[c]cinnoline, amidinate, formate, and hydroxo complexes. These results expand the range of known bond transformations at iron complexes. Additionally, they give insight into the elementary transformations that may be possible at the iron-molybdenum cofactor of nitrogenases, which may have hydride ligands on high-spin, low coordinate metal atoms. PMID:18444648

Yu, Ying; Sadique, Azwana R.; Smith, Jeremy M.; Dugan, Thomas R.; Cowley, Ryan E.; Brennessel, William W.; Flaschenriem, Christine J.; Bill, Eckhard; Cundari, Thomas R.; Holland, Patrick L.

2008-01-01

378

Air passivation of metal hydride beds for waste disposal  

SciTech Connect

One waste acceptance criteria for hydride bed waste disposal is that the bed be non-pyrophoric. Batch-wise air ingress tests were performed which determined the amount of air consumed by a metal hydride bed. A desorbed, 4.4 kg titanium prototype hydride storage vessel (HSV) produced a 4.4 deg.C internal temperature rise upon the first air exposure cycle and a 0.1 deg.C temperature rise upon a second air exposure. A total of 346 sec air was consumed by the bed (0.08 sec 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 12. cycle. Nine to ten STP-L of air reacted with the bed producing both oxidized metal and water. (authors)

Klein, J. E.; Hsu, R. H. [Savannah River National Laboratory, Aiken, SC 29808 (United States)

2008-07-15

379

Superconductive sodalite-like clathrate calcium hydride at high pressures  

PubMed Central

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

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

2012-01-01

380

Structure and properties of complex hydride perovskite materials.  

PubMed

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

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

2014-01-01

381

Structure and properties of complex hydride perovskite materials  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

382

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.

2000-09-01

383

Mercury in the Anthropocene Ocean  

E-print Network

The toxic metal mercury is present only at trace levels in the ocean, but it accumulates in fish at concentrations high enough to pose a threat to human and environmental health. Human activity has dramatically altered the ...

Lamborg, Carl

384

"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

385

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

386

Mercury Toolset for Spatiotemporal Metadata  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

387

Rapid mercury assays  

SciTech Connect

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

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

1996-10-01

388

Mercury ion thruster technology  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

389

Hydride affinities of cumulated, isolated, and conjugated dienes in acetonitrile.  

PubMed

The hydride affinities (defined as the enthalpy changes in this work) of 15 polarized dienes [five phenyl sulfone substituted allenes (1a), the corresponding five isolated dienes (1b), and the corresponding five conjugated dienes (1c)] in acetonitrile solution were determined by titration calorimetry for the first time. The results display that the hydride affinity scales of the 15 dienes in acetonitrile range from -71.6 to -73.9 kcal/mol for 1a, from -46.2 to -49.7 kcal/mol for 1b, and from -45.0 to -46.5 kcal/mol for 1c, which indicates that the hydride-obtaining abilities of the cumulated dienes (1a) are not only much larger than those of the corresponding conjugated dienes (1c) but also much larger than those of the corresponding isolated dienes (1b). The hydrogen affinities of the 15 dienes as well as the hydrogen affinities and the proton affinities of the radical anions of the dienes (1(-*)) in acetonitrile were also evaluated by using relative thermodynamic cycles according to Hess's law. The results show that (i) the hydrogen affinities of the neutral dienes 1 cover a range from -44.5 to -45.6 kcal/mol for 1a, from -20.4 to -21.4 kcal/mol for 1b, and from -17.3 to -18.5 kcal/mol for 1c; (ii) the hydrogen affinities of the radical anions of the dienes (1(-*)) in acetonitrile cover a range from -40.6 to -47.2 kcal/mol for 1a(-*), from -21.6 to -29.6 kcal/mol for 1b(-*), and from -10.0 to -15.4 kcal/mol for 1c(-*); (iii) the proton affinities of the 15 1a(-*) in acetonitrile cover a range from -97.0 to -100.6 kcal/mol for 1a(-*), from -77.8 to -83.4 kcal/mol for 1b(-*), and from -66.2 to -68.9 kcal/mol for 1c(-*). The main reasons for the great difference between the cumulated dienes and the corresponding isolated and conjugated dienes in the hydride affinity, hydrogen affinity, and proton affinity have been examined. It is evident that these experimental results should be quite valuable to facilitate the elucidation of the origins of the especially high chemical potencies of the allenes, the choice of suitable hydride reducing agents to reduce the dienes, and the analyses on the reduction mechanisms. PMID:18821805

Zhu, Xiao-Qing; Liang, Hao; Zhu, Yan; Cheng, Jin-Pei

2008-11-01

390

Synthesis of Highly Active Mg-BASED Hydrides Using Hydriding Combustion Synthesis and NbF5 Additives  

NASA Astrophysics Data System (ADS)

Superiority of the hydriding combustion (HC) technique over conventional metallurgical approach to the synthesis of cost-effective Mg based hydrides, which show promise as hydrogen storage materials, is well known. In the present research, we report further improvements in HC prepared Mg-based materials, achieved by optimizing the preparative parameters of HC and by catalytic addition. Mg90-Ni60-C40 composites prepared using optimized processing parameters were ball-milled with NbF5 (10 h) and characterized for their micro-structural and hydriding properties. The ball-milled/catalyzed powder showed decreased crystallinity with CNTs on its surfaces. Surface area of the ball-milled powder decreased to almost half of the as-HC powder, while TG analysis revealed a four-fold decrease in the desorption temperature of the milled powder compared to that of the as-HC prepared powder. Activated samples achieved the maximum absorption/desorption limits (5.3 wt.%) at as low as 100°C, underlining the possibility of the use of these materials in portable hydrogen storage devices.

Chourashiya, M. G.; Park, C. N.; Park, C. J.

2012-09-01

391

IntroductionIntroduction Mercury: Monitoring Patients with ParkinsonMercury: Monitoring Patients with Parkinson''s Diseases Disease  

E-print Network

IntroductionIntroduction Mercury: Monitoring Patients with ParkinsonMercury: Monitoring Patients's Disease EvaluationEvaluation Mercury ArchitectureMercury Architecture Mercury is a wireless sensor network and disconnections Node Behavior Hardware PlatformHardware Platform Usage Scenario InternetInternet http://fiji.eecs.harvard.edu/Mercury

Chen, Yiling

392

Source-attribution for atmospheric mercury deposition: Where does the mercury in mercury deposition come from?  

E-print Network

-emission of natural AND previously deposited anthropogenic mercury Adsorption/ desorption of Hg(II) to /from soot Hg, fuels and raw materials, pollution control equipment, etc. #12;18 Estimated 1999 U.S. Atmospheric

393

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

394

Mercury Methylation and Environmental Effects of Inactive Mercury Mines in the Circum-Pacific Region  

NASA Astrophysics Data System (ADS)

Mercury mines worldwide contain of some the highest concentrations of mercury on earth, and as a result of local mercury contamination, these mines represent areas of environmental concern when mine-drainage enters downstream aquatic systems. The most problematic aspect of mine site mercury contamination is the conversion of inorganic mercury to highly toxic organic mercury compounds, such as methylmercury, and their subsequent uptake by aquatic organisms in surrounding ecosystems. Mercury and methylmercury concentrations were measured in sediment and water samples collected from several inactive mercury mines in Nevada, Alaska, and the Philippines, which are part of the circum-Pacific mineral belt. The mines studied represent different mercury deposit types and sizes, and climatic settings. Geochemical data collected from these mines indicate that areas surrounding hot-springs type mercury deposits generally have lower methylmercury concentrations than silica-carbonate mercury deposits. In hot-springs mercury deposits in Nevada and Alaska, ore is dominantly cinnabar with few acid-water generating minerals such as pyrite, and as a result, mine-water drainage has near neutral pH in which there is low solubility of mercury. Conversely, silica-carbonate deposits, such as Palawan, Philippines, contain abundant cinnabar and pyrite, and the resultant acidic-mine drainage generally has higher concentrations of mercury and methylmercury. Additional factors such as the proximity of mercury mines to wetlands, climatic effects, or mine wastes containing highly soluble mercury compounds potentially enhance mercury methylation. The Palawan mercury mine may be a unique example where several adverse environmental factors produced local mercury contamination, high mercury methylation, fish contamination, and mercury poisoning of humans that consumed these contaminated fish.

Gray, J. E.

2001-05-01

395

Mercury Changes Songs Dire effects of mercury contamination on birds' physiology  

E-print Network

Mercury Changes Songs Dire effects of mercury contamination on birds' physiology and behavior make higher blood mercury levels at the contaminated sites compared to the uncontaminated sites (Science 320 up an alarming list of pathologies, and now we can add one more: Mercury in the diet may be poi

Irwin, Darren

396

Mercury-Mercury Tunneling Junctions. 1. Electron Tunneling Across Symmetric and Asymmetric Alkanethiolate Bilayers  

E-print Network

Mercury-Mercury Tunneling Junctions. 1. Electron Tunneling Across Symmetric and Asymmetric by bringing in contact two small (3 × 10-3 cm2) mercury drop electrodes in a 5-20% (v/v) hexadecane solution incorporating alkanethiolate-type monolayer films. The results reported below convince us that the mercury

Majda, Marcin

397

Groundwater Modeling Of Mercury Pollution At A Former Mercury Cell Chlor Alkali Facility In Pavoldar, Kazakhstan  

EPA Science Inventory

In Kazakhstan, there is a serious case of mercury pollution near the city of Pavlodar from an old mercury cell chlor-alkali plant. The soil, sediment, and water is severly contaminated with mercury and mercury compounds as a result of the industrial activity of this chemical pla...

398

Mercury: Aspects of its ecology and environmental toxicity. [physiological effects of mercury compound contamination of environment  

NASA Technical Reports Server (NTRS)

A study was conducted to determine the effects of mercury pollution on the environment. The possible sources of mercury contamination in sea water are identified. The effects of mercury on food sources, as represented by swordfish, are analyzed. The physiological effects of varying concentrations of mercury are reported. Emphasis is placed on the situation existing in the Hawaiian Islands.

Siegel, S. M.

1973-01-01

399

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

400

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

DOEpatents

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

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

2014-11-18

401

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.

402

Mercury in smoke from biomass fires  

NASA Astrophysics Data System (ADS)

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

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

403

The curious case of Mercury's internal structure  

E-print Network

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

Hauck, Steven A.

404

Mercury Air Pollution Reflected in Ocean Fish  

MedlinePLUS

... features on this page, please enable JavaScript. Mercury Air Pollution Reflected in Ocean Fish, Study Says Concentrations in ... mercury in the open ocean is fallout from air pollution, especially from coal-fired power plants and artisanal ...

405

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

NASA Video Gallery

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

406

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...

407

Understanding Thimerosal, Mercury, and Vaccine Safety  

MedlinePLUS

Understanding Thimerosal, Mercury, and Vaccine Safety ? For more information on vaccines, vaccine-preventable diseases, and vaccine safety: http://www.cdc.gov/ ... thimerosal as a preservative from vaccines to reduce mercury exposure among infants as much as possible. • Today, ...

408

Mercury Poisoning Linked to Skin Products  

MedlinePLUS

... mail this page Home For Consumers Consumer Updates Mercury Poisoning Linked to Skin Products Search the Consumer ... these products on Flickr. Signs and Symptoms of Mercury Poisoning irritability shyness tremors changes in vision or ...

409

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 (...

410

Mercury contamination study for flight system safety  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

411

METHYLATION OF MERCURY IN AGRICULTURAL SOILS  

EPA Science Inventory

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

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

1997-01-01

413

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

414

In-situ study of hydride precipitation kinetics and re-orientation in Zircaloy using synchrotron radiation  

E-print Network

, mechanical resistance, especially in degradation processes such as delayed hydride cracking. The hydride in previously hydrided Zircaloy samples. The hydrogen solubility limit observed in situ was 1 #12;found in light water reactors (LWR) causes hydrogen pickup into the zirconium alloy cladding of the reactor fuel

Motta, Arthur T.

415

EDITORIAL: Mercury-free discharges for lighting  

Microsoft Academic Search

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

M. Haverlag

2007-01-01

416

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

417

Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant Pseudomonas putida strain  

Microsoft Academic Search

A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.6 mg\\/liter and high chloride concentrations and had pH values which

H. von Canstein; Y. Li; K. N. Timmis; W.-D. DECKWER; I. Wagner-Doebler

1999-01-01

418

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

Microsoft Academic Search

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

Wang Kan; Greenspan Ehud

2004-01-01

419

Complex Hydrides for Hydrogen Storage Darlene K. Slattery and Michael D. Hampton  

E-print Network

Complex Hydrides for Hydrogen Storage Darlene K. Slattery and Michael D. Hampton Florida Solar Energy Center 1679 Clearlake Road Cocoa, FL 32922 Abstract Complex hydrides, containing a minimum of 7.5 wt% hydrogen, are being investigated as hydrogen storage compounds for automotive use. As a new

420

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

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

2012-01-01

421

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

422

Fermi levels of FCC and FCT hydrides of Ti and Zr  

NASA Astrophysics Data System (ADS)

Measurements of the work functions of films of TiH x and ZrH x during the FCC/FCT transition have given the change of Fermi level between these two phases of the hydrides. The results agree with modern calculations of the band structures of these hydrides.

Kandasamy, K.; Surplice, N. A.

1984-03-01

423

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

424

Silicon nanowires as a rechargeable template for hydride transfer in redox biocatalysis  

NASA Astrophysics Data System (ADS)

We report a new possible application of hydrogen-terminated silicon nanowires (H-SiNWs) as a rechargeable template for hydride transfer in redox biocatalysis. H-SiNWs transfer hydride efficiently to regenerate NADH by oxidizing Si-Hx bonds. The oxidized H-SiNWs were readily recharged for the continuous regeneration of NADH and enzymatic reactions.

Lee, Hwa Young; Kim, Jae Hong; Son, Eun Jin; Park, Chan Beum

2012-11-01

425

Theory of the chemical bond. V. Bond polarities of post-transition hydrides  

Microsoft Academic Search

A classical derivation of a dipole moment model derived earlier by a quantum mechanical implicit perturbation technique is given. This model is used to determine the bond polarities of the post transition (Groups IIIA–VIIA) hydrides. The polarity measures the extent of charge transfer in a bond. Polarities of alkali halides and posttransition hydrides are used to illustrate the gradual change

Robert L. Matcha; Stephen C. King; B. M. Pettitt

1980-01-01

426

Theory of the chemical bond. V. Bond polarities of post-transition hydrides  

Microsoft Academic Search

A classical derivation of a dipole moment model derived earlier by a quantum mechanical implicit perturbation technique is given. This model is used to determine the bond polarities of the post transition (Groups IIIA-VIIA) hydrides. The polarity measures the extent of charge transfer in a bond. Polarities of alkali halides and posttransition hydrides are used to illustrate the gradual change

Robert L. Matcha; Stephen C. King; B. M. Pettitt

1980-01-01

427

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

428

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.

Environmental Science and Technology Online

429

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

430

REPLACE YOUR MERCURY THERMOMETERS BEFORE THEY BREAK!  

E-print Network

REPLACE YOUR MERCURY THERMOMETERS BEFORE THEY BREAK! Did you know, mercury from broken thermometers to the local environment, if broken thermometers in sinks eventually end at the sanitary sewer plant. Broken mercury thermometers create hazardous waste that is costly to clean up and costly to dispose of. Other

431

MERCURY CONTROL TECHNOLOGY--A REVIEW  

EPA Science Inventory

The U.S. Environmental Protection Agency has promulgated the Clean Air Mercury Rule (CAMR) to permanently cap and reduce mercury emissions in the U.S. This rule makes the U.S. the first country in the world to regulate mercury emissions from coal-fired power plants. The first p...

432

Constraining Mercury Oxidation Using Wet Deposition  

E-print Network

Constraining Mercury Oxidation Using Wet Deposition Noelle E. Selin and Christopher D. Holmes mercury oxidation [Selin & Jacob, Atmos. Env. 2008] 30 60 90 120 150 30 60 90 120 150 30 60 90 120 150 30 Influences on Mercury Wet Deposition · Hg wet dep = f(precipitation, [Hg(II)+Hg(P)]) Correlation (r2) between

Selin, Noelle Eckley

433

40 CFR 721.10068 - Elemental mercury.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 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...

2014-07-01

434

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

435

40 CFR 721.10068 - Elemental mercury.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Elemental mercury. 721.10068 Section 721.10068...Substances § 721.10068 Elemental mercury. (a) Definitions . The definitions...1) The chemical substance elemental mercury (CAS. No. 7439-97-6) is...

2011-07-01

436

Mercury Chamber NF-IDS Meeting  

E-print Network

Mercury Chamber Update V. Graves NF-IDS Meeting October 4, 2011 #12;2 Managed by UT-Battelle for the U.S. Department of Energy Mercury Chamber Update Oct 2011 Starting Point: Coil and Shielding Concept IDS120H #12;3 Managed by UT-Battelle for the U.S. Department of Energy Mercury Chamber Update Oct 2011

McDonald, Kirk

437

40 CFR 721.10068 - Elemental mercury.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 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...

2012-07-01

438

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

439

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

440

Atmospheric Chemistry, Modeling, and Biogeochemistry of Mercury  

E-print Network

Atmospheric Chemistry, Modeling, and Biogeochemistry of Mercury Noelle Eckley Selin *Reprinted from Mercury in the Environment: Pattern and Process (Chapter 5) pp. 73-80 Copyright © 2012 with kind, and Biogeochemistry of Mercury NOELLE ECKLEY SELIN and their distribution in the atmosphere. This includes

441

Mercury: Recovering Forgotten Passwords Using Personal Devices  

E-print Network

Mercury: Recovering Forgotten Passwords Using Personal Devices Mohammad Mannan1 , David Barrera2, and to allow forgotten passwords to be securely restored, we present a scheme called Mercury. Its primary mode and revealed to the user. A prototype implementation of Mercury is available as an Android application. 1

Van Oorschot, Paul

442

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

443

2003 Mercury Computer Systems, Inc. Delivered Performance  

E-print Network

© 2003 Mercury Computer Systems, Inc. Delivered Performance Predictions and Trends for RISC Applications Luke Cico (lcico@mc.com) Mark Merritt (mmerritt@mc.com) Mercury Computer Systems, Inc. Chelmsford, MA 01824 #12;© 2003 Mercury Computer Systems, Inc. Goals of PresentationGoals of Presentation

Kepner, Jeremy

444

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

445

2003 Mercury Computer Systems, Inc. Data Reorganization  

E-print Network

© 2003 Mercury Computer Systems, Inc. Data Reorganization Interface (DRI) Data Reorganization Interface (DRI) Kenneth Cain Jr. Mercury Computer Systems, Inc. High Performance Embedded Computing (HPEC Mercury Computer Systems, Inc. Status update for the DRI-1.0 standard since Sep. 2002 publication Outline

Kepner, Jeremy

446

3, 35253541, 2003 Modelling of Mercury  

E-print Network

ACPD 3, 3525­3541, 2003 Modelling of Mercury with the Danish Eulerian Hemispheric Model J. H and Physics Discussions Modelling of mercury with the Danish Eulerian Hemispheric Model J. H. Christensen, J Correspondence to: J. H. Christensen (jc@dmu.dk) 3525 #12;ACPD 3, 3525­3541, 2003 Modelling of Mercury

Paris-Sud XI, Université de

447

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

448

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON  

EPA Science Inventory

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

449

TRANSIT OF MERCURY PREPARING FOR VENUS  

E-print Network

TRANSIT OF MERCURY PREPARING FOR VENUS Günther Wuchterl, MPE #12;2003 Preparations · ESA/SOHO; mirrors · Media-warmup: Evening vis., LASCO #12;Mercury approaching Transit: SOHO/LASCO C3 Mercury #12" #12;SOHO ­ the movie SOHO ---- the movie Quicktime, made available via ftp, since ESA-TV satellite

Wuchterl, Günther

450

Ecological effects of mercury in aquatic ecosystems  

SciTech Connect

As a result of former mining operations, roughly 100 tons of mercury were released into Clear Lake, California. In 1992 the authors conducted a baseline survey designed to evaluate the levels and potential effects of mercury within this aquatic ecosystem. Both surficial sediments and cores confirm a clear exponential decline in total mercury and methyl mercury as a function of distance from the mine site. The ratio of methyl/total mercury in surficial sediments, however, increases exponentially as a function of distance from the mine. Declines in total mercury in water were not as steep as for sediments. Plankton, oligochaetes and chironomids also exhibited exponential declines in total mercury but not methyl mercury as a function of distance from the mine. Patterns of invertebrate population and community level parameters will be discussed in relation to mercury and other potential pollutants. Fish showed increasing mercury levels with increasing body size and the following species specific differences: carp < silversides < channel catfish < largemouth bass. Some higher than expected levels of methyl mercury were found at sites distant from the mine. An hypothesis to explain these methyl mercury distributions as a function of bioavailability will be presented.

Suchanek, T.H.; Richerson, P.J. [Univ. of California, Davis, CA (United States). Division of Environmental Studies

1994-12-31

451

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

452

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

453

Getting metal-hydrides to do what you want them to  

SciTech Connect

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

Gruen, D.M.

1981-01-01

454

Mathematical modeling of the nickel/metal hydride battery system  

SciTech Connect

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

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

1995-09-01

455

Improvement in thallium hydride generation using iodide and Rhodamine B.  

PubMed

A continuous flow hydride generation atomic absorption spectrometry (CF-HG-AAS) system was used to study the enhancement effect of different substances for conventional chemical HG of thallium. At room temperature, the acidified sample solution containing the respective enhancement reagent merged with the aqueous NaBH4 solution. The generated thallium hydride was stripped from the eluent solution by the addition of a nitrogen flow and thereafter the bulk phases were separated in a gas-liquid separator. The main factors under study were concentration and type of enhancement reagent (Te, iodide added as KI, Rhodamine B, malachite green and crystal violet) and acid (HCl, H2SO4 or HNO3). Other parameters affecting the thallium hydride generation, such as: NaBH4 concentration, carrier gas flow rate, length of reaction-mixing coil and reagents flow rates, were studied and optimized. Among the enhancement reagents tested, the combination of Rhodamine B and iodide produced the best results. A linear response was obtained between the detection limit (LOD (3?)) of 1.5?gL(-1) and 1000?gL(-1). The RSD% (n=10) for a solution containing 15?gL(-1) of Tl was 2.9%. The recoveries of thallium in environmental water samples by spiking the samples with 10 and 20µgL(-1) of Tl were in the 97.0-102.5% range. The accuracy for Tl determination was further confirmed by the analysis of a water standard reference material (1643e form NIST, USA). Finally, it was demonstrated that malachite green and crystal violet showed similar enhancement effect like Rhodamine B for thallium HG. PMID:25702995

Picón, David; Carrero, Pablo; Valero, Maribel; de Peña, Yaneira Petit; Gutiérrez, Luís

2015-05-01

456

ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE  

SciTech Connect

Hydrogen storage is one of the greatest challenges for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods; the direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, in the isolation of alane from the mixtures of the electrochemical cell. Alane is isolated as the triethylamine (TEA) adduct and converted to pure, unsolvated alane by heating under vacuum.

Fewox, C; Ragaiy Zidan, R; Brenda Garcia-Diaz, B

2008-12-31

457

ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE  

SciTech Connect

Hydrogen storage is one of the challenges to be overcome for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods. The direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali metal alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, in the isolation of alane from the mixtures of the electrochemical cell. Alane is isolated as the triethylamine (TEA) adduct and converted to pure, unsolvated alane by heating under vacuum.

Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B; Joshua Gray, J

2009-01-09

458

Influence of Mercury  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

459

Stress analysis of hydride bed vessels used for tritium storage  

SciTech Connect

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

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

1991-12-31

460

Stress analysis of hydride bed vessels used for tritium storage  

SciTech Connect

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

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

1991-01-01

461

Electrochemical process and production of novel complex hydrides  

DOEpatents

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

Zidan, Ragaiy

2013-06-25

462

Bipolar Nickel-Metal Hydride Battery Development Project  

NASA Technical Reports Server (NTRS)

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

Cole, John H.

1999-01-01

463

The calculated rovibronic spectrum of scandium hydride, ScH  

E-print Network

The electronic structure of six low-lying electronic states of scandium hydride, $X\\,{}^{1}\\Sigma^+$, $a\\,{}^{3}\\Delta$, $b\\,{}^{3}\\Pi$, $A\\,{}^{1}\\Delta$ $c\\,{}^{3}\\Sigma^+$, and $B\\,{}^{1}\\Pi$, is studied using multi-reference configuration interaction as a function of bond length. Diagonal and off-diagonal dipole moment, spin-orbit coupling and electronic angular momentum curves are also computed. The results are benchmarked against experimental measurements and calculations on atomic scandium. The resulting curves are used to compute a line list of molecular ro-vibronic transitions for $^{45}$ScH.

Lodi, Lorenzo; Tennyson\\, Jonathan

2015-01-01

464

Chemical Hydrides for Hydrogen Storage in Fuel Cell Applications  

SciTech Connect

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

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

2012-04-16

465

Statistical theory of forming structural vacancies in palladium hydride  

NASA Astrophysics Data System (ADS)

Based on molecular-kinetic representations, the theory of forming structural vacancies and vacant-ordered superstructure of Cu3Au type in palladium hydride is developed. Free energies of PdH and Pd3VH4 phases are calculated. The constitution diagram is constructed that determines ranges of temperature and concentration in which phases with A1 and L12 structures are formed and regions of two A1 + L12 phases are realized. Results of theoretical calculations are in agreement with the available experimental data.

Zaginaichenko, S. Yu.; Matysina, Z. A.; Shchur, D. V.

2011-07-01

466

Geoneutrinos and Hydridic Earth (or primordially hydrogen-rich planet)  

NASA Astrophysics Data System (ADS)

Geoneutrino is a new channel of information about geochemical composition of the Earth. We analyzed here the following problem. What statistics do we need to distinguish between predictions of Bulk Silicate Earth model and Hydridic Earth model for Th/U signal ratio? We obtained the simple formula for estimation of error of Th/U signal ratio. Our calculations show that we need more than 22 kt · year exposition for Gran-Sasso underground laboratory and Sudbury Neutrino Observatory. We need more than 27 kt · year exposition for Kamioka site in the case of stopping of all Japanese nuclear power plants.

Bezrukov, L.; Sinev, V.

2015-03-01

467

Metal hydride based isotope separation: Large-scale operations  

SciTech Connect

A program to develop a metal hydride based hydrogen isotope separation process began at the Savannah River Laboratory in 1980. This semi-continuous gas chromatographic separation process will be used in new tritium facilities at the Savannah River Site. A tritium production unit is scheduled to start operation in 1993. An experimental, large-scale unit is currently being tested using protium and deuterium. Operation of the large-scale unit has demonstrated separation of mixed hydrogen isotopes (55% protium and 45% deuterium), resulting in protium and deuterium product streams with purities better than 99.5%. 3 refs., 4 figs.

Horen, A.S.; Lee, Myung W.

1991-12-31

468

Metal hydride based isotope separation: Large-scale operations  

SciTech Connect

A program to develop a metal hydride based hydrogen isotope separation process began at the Savannah River Laboratory in 1980. This semi-continuous gas chromatographic separation process will be used in new tritium facilities at the Savannah River Site. A tritium production unit is scheduled to start operation in 1993. An experimental, large-scale unit is currently being tested using protium and deuterium. Operation of the large-scale unit has demonstrated separation of mixed hydrogen isotopes (55% protium and 45% deuterium), resulting in protium and deuterium product streams with purities better than 99.5%. 3 refs., 4 figs.

Horen, A.S.; Lee, Myung W.

1991-01-01

469

Multiscale magnetic turbulence at Mercury  

NASA Astrophysics Data System (ADS)

A set of statistical-physical tools is used to investigate multiscale magnetic field fluctuations recorded by MESSENGER spacecraft in the near-Mercury space environment, with the emphasis on key boundary regions participating in the solar wind - magnetosphere interaction. The analysis reveals the presence of a highly turbulent and extended foreshock system filled with packets of ULF oscillations and active current sheets, broad-band intermittent fluctuations in the magnetosheath, ion-kinetic turbulence in the central plasma sheet of Mercury's magnetotail, and kinetic-scale fluctuations in the inner current sheet encountered at the outbound (dawn side) magnetopause. The obtained statistics suggest that turbulence at this planet is strongly affected by non-MHD effects introduced by finite sizes of cyclotron orbits of the constituting ion species. Physical mechanisms of these effects and their influence on the structure and dynamics of Mercury's magnetic field remain to be clarified.

Uritsky, Vadim; Slavin, James; Boardsen, Scott; Sundberg, Torbjorn; Raines, James; Gershman, Daniel; Zurbuchen, Thomas; Khazanov, George; Anderson, Brian; Korth, Haje

2014-05-01

470

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

471

Mercury Project - Little Joe capsule  

NASA Technical Reports Server (NTRS)

Assembling the Little Joe capsule. This workman signed and taped in a twenty-dollar bill to be carried along with the mission. The capsules were manufactured 'in-house' by Langley technicians. Joseph Shortal wrote (vol. 3, p. 32): 'Design of the Little Joe capsules began at Langley before McDonnell started on the design of the Mercury capsule and was, therefore, a separate design. Although it was not designed to carry a man, it did have to carry a monkey. It had to meet the weight and center of gravity requirements of Mercury and withstand the same aerodynamic loads during the exit trajectory.' 'Although in comparison with the overall Mercury Project, Little Joe was a simple undertaking, the fact that an attempt was made to condense a normal two-year project into a 6-month one with in house labor turned it into a major undertaking for Langley.'

1959-01-01

472

Sodium Velocity Maps on Mercury  

NASA Technical Reports Server (NTRS)

The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

Potter, A. E.; Killen, R. M.

2011-01-01

473

Shepard Hoisted from Mercury Capsule  

NASA Technical Reports Server (NTRS)

A U.S. Marine helicopter recovery team hoists astronaut Alan Shepard from his Mercury spacecraft after a successful flight and splashdown in the Atlantic Ocean. On May 5th 1961, Alan B. Shepard Jr. became the first American to fly into space. His Freedom 7 Mercury capsule flew a suborbital trajectory lasting 15 minutes 22 seconds. His spacecraft landed in the Atlantic Ocean where he and his capsule were recovered by helicopter and transported to the awaiting aircraft carrier U.S.S. Lake Champlain.

1961-01-01

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

Measuring mercury in coastal fog water  

NASA Astrophysics Data System (ADS)

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

Balcerak, Ernie

2012-04-01

476

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. PMID:24170977

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

2013-01-01

477

Mercury biogeochemistry: Paradigm shifts, outstanding issues and research needs  

NASA Astrophysics Data System (ADS)

Half a century of mercury research has provided scientists and policy makers with a detailed understanding of mercury toxicology, biogeochemical cycling and past and future impacts on human exposure. The complexity of the global biogeochemical mercury cycle has led to repeated and ongoing paradigm shifts in numerous mercury-related disciplines and outstanding questions remain. In this review, we highlight some of the paradigm shifts and questions on mercury toxicity, the risks and benefits of seafood consumption, the source of mercury in seafood, and the Arctic mercury cycle. We see a continued need for research on mercury toxicology and epidemiology, for marine mercury dynamics and ecology, and for a closer collaboration between observational mercury science and mercury modeling in general. As anthropogenic mercury emissions are closely tied to the energy cycle (in particular coal combustion), mercury exposure to humans and wildlife are likely to persist unless drastic emission reductions are put in place.

Sonke, Jeroen E.; Heimbürger, Lars-Eric; Dommergue, Aurélien

2013-05-01

478

Mercury and platinum abundances in mercury-manganese stars  

E-print Network

We report new results for the elemental and isotopic abundances of the normally rare elements mercury and platinum in HgMn stars. Typical overabundances can be 4 dex or more. The isotopic patterns do not follow the fractionation model of White et al (1976).

C. M. Jomaron; M. M. Dworetsky; D. A. Bohlender

1998-05-06

479

Remote process cell mercury transfer pumps for DWPF. [Mercury  

Microsoft Academic Search

Final design and the results of the testing performed thus far show that the water displacement of mercury to a height of 40 feet is feasible with just 6 gallons of motive water. Control of the transfer is achieved by monitoring the pump discharge pressure. An air actuated plug valve configuration successfully contained the required discharge pressure of 260 psi.

M. G. Nielsen; V. G. Vaughn

1986-01-01

480

Reactions of ruthenium hydrides with ethyl-vinyl sulfide.  

PubMed

The Ru-hydride precursors (Im(OMe)2)(PPh3)2RuHCl () and (Me2Im(OMe)2)(PPh3)2RuHCl () reacted with ethyl-vinyl-sulfide to give ((MeOCH2CH2)C3H2N2(CH2CH(OMe))RuCl(PPh3)2 () and ((MeOCH2CH2)C3Me2N2(CH2CH(OMe))RuCl(PPh3)2 (), respectively. Dissolution of () in C6D6 prompts formation of ((MeOCH2CH2)C5H6N2(CHCH)RuCl(PPh3)2 (). The analogous reactions of the bis-carbene Ru-hydride precursors (Im(OMe)2)(IMes)(PPh3)RuHCl (), (Im(OMe)2)(SIMes)(PPh3)RuHCl () and (Im(OMe)2)(IMes-Cl2)(PPh3)RuHCl () gave ((MeOCH2CH2)C3H2N2(CHCH)RuCl(PPh3)(NHC) (NHC = IMes (), SIMes (), IMes-Cl2 (), respectively. The formation of compounds () and () is thought to go through an initial insertion of the vinyl-fragment into the Ru-H prompting subsequent C-H activation and loss of diethyl sulfide. This yields () and (), while subsequent loss of methanol yields () and (-). PMID:24441082

Dahcheh, Fatme; Stephan, Douglas W

2014-03-01

481

[Mercury sensitization induced by environmental exposure].  

PubMed

We investigated mercury sensitization in relation to urinary and hair mercury concentrations. Patch tests were performed on 215 medical students and these tests demonstrated that 28 students were mercury-sensitized (13.0%). Life-styles were studied by questionnaire in 26 of the mercury sensitized students and 46 of the non-sensitized subjects. Urinary mercury concentrations were measured in 25 sensitized and 46 non-sensitized and hair mercury concentrations were measured in 19 sensitized and 22 non-sensitized subjects. The eating of fish was not significantly associated with mercury sensitization (one-tailed t-test). The number of teeth treated with metals in the sensitized group was significantly higher than in the control group (6.8 +/- 4.3 in sensitized vs. 4.8 +/- 4.1 in non-sensitized, one-tailed t-test. p < 0.05). The usage of mercurochrome was not significantly associated with mercury sensitization (chi-squared test). Urinary mercury concentrations were not significantly higher in sensitized subjects. Hair mercury concentrations were significantly higher in sensitized subjects (1.98 +/- 0.91 micrograms/g in sensitized vs. 1.23 +/- 0.53 in non-sensitized, one-tailed t-test p < 0.05). These results suggest that mercury sensitization is associated with increased hair mercury concentrations but not with urinary mercury concentrations. In this study it is confirmed that dental amalgam for treating teeth may be an important factor relating to mercury sensitization. PMID:9528265

Mori, T; Hirai, T; Tomiyama, T; Iida, K; Miyakoshi, S; Sato, K; Kusaka, Y; Yanagihara, M; Ueda, K

1998-01-01

482

Multi-scale characterization of nanostructured sodium aluminum hydride  

NASA Astrophysics Data System (ADS)

Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to improve in performance and reversibility. This area of research has garnered immense interest lately and there is active research being pursued to address various aspects of nanostructured complex hydrides. The research effort documented here is focused on a detailed investigation of the effects of nano-confinement on aspects such as the long range atomic hydrogen diffusivities, localized hydrogen dynamics, microstructure, and dehydrogenation mechanism of sodium alanate. A wide variety of microporous and mesoporous materials (metal organic frameworks, porous silica and alumina) were investigated as scaffolds and the synthesis routes to achieve maximum pore-loading are discussed. Wet solution infiltration technique was adopted using tetrahydrofuran as the medium and the precursor concentrations were found to have a major role in achieving maximum pore loading. These concentrations were optimized for each scaffold with varying pore sizes and confinement was quantitatively characterized by measuring the loss in specific surface area. This work is also aimed at utilizing neutron and synchrotron x-ray characterization techniques to study and correlate multi-scale material properties and phenomena. Some of the most advanced instruments were utilized for this work and their data collection and analysis are reported. Quasielastic neutron scattering experiments were conducted at NIST Center for Neutron Research to characterize atomic hydrogen diffusion in bulk and nano-confined NaAlH4. It was observed that upon confinement of NaAlH4, a significantly higher fraction of hydrogen atoms were involved in diffusive motion on the pico-second to nano-second timescales. However, the confinement had no impact on the lattice diffusivities (jump/hopping rates) of atomic hydrogen, indicating that the improved hydrogen release rates were not due to any kinetic destabilization effects. Instead, the investigation strongly suggested thermodynamic destabilization as the major effect of nano-confinement. The local interaction of the metal sites in metal organic frameworks with the infiltrated hydride was studied using extended x-ray absorption spectroscopy technique. The experiments were conducted at Center for Advanced Microstructures and Devices at Louisiana State University. The metal sites were found to be chemically un-altered, hence ruling out any catalytic role in the dehydrogenation at room temperatures. The fractal morphology of NaAlH4 was characterized by ultra-small angle x-ray scattering experiments performed at Argonne National Lab. The studies quantitatively estimated the extent of densification in the course of one desorption cycle. The particle sizes were found to increase two-fold during heat treatment. Also, the nano-confinement procedure was shown to produce dense mass fractals as opposed to pristine NaAlH4, exhibiting a surface fractal morphology. Based on this finding, a new method to identify confined material from un-confined material in nano-composites was developed and is presented. Preliminary results of modeling and correlating multi-scale phenomena using a phase-field approach are also presented as the foundation for future work.

NaraseGowda, Shathabish