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1

Quantifying uncertainty in measurement of mercury in suspended particulate matter by cold vapor technique using atomic absorption spectrometry with hydride generator.  

PubMed

As a result of rapid industrialization several chemical forms of organic and inorganic mercury are constantly introduced to the environment and affect humans and animals directly. All forms of mercury have toxic effects; therefore accurate measurement of mercury is of prime importance especially in suspended particulate matter (SPM) collected through high volume sampler (HVS). In the quantification of mercury in SPM samples several steps are involved from sampling to final result. The quality, reliability and confidence level of the analyzed data depends upon the measurement uncertainty of the whole process. Evaluation of measurement uncertainty of results is one of the requirements of the standard ISO/IEC 17025:2005 (European Standard EN IS/ISO/IEC 17025:2005, issue1:1-28, 2006). In the presented study the uncertainty estimation in mercury determination in suspended particulate matter (SPM) has been carried out using cold vapor Atomic Absorption Spectrometer-Hydride Generator (AAS-HG) technique followed by wet chemical digestion process. For the calculation of uncertainty, we have considered many general potential sources of uncertainty. After the analysis of data of seven diverse sites of Delhi, it has been concluded that the mercury concentration varies from 1.59?±?0.37 to 14.5?±?2.9 ng/m(3) with 95% confidence level (k?=?2). PMID:24083104

Singh, Nahar; Ahuja, Tarushee; Ojha, Vijay Narain; Soni, Daya; Tripathy, S Swarupa; Leito, Ivo

2013-01-01

2

Mercury  

SciTech Connect

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

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

1988-01-01

3

Mercury  

MedlinePLUS

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

4

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

PubMed

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

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

2013-01-01

5

Mercury  

MedlinePLUS

... has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a ... products. Metallic mercury is used in glass thermometers, silver dental fillings, and button batteries. Mercury salts may ...

6

Mercury  

NSDL National Science Digital Library

This site offers information on the planet Mercury. Some topics include: the atmosphere, surface, and interior of Mercury, missions to Mercury, recent discoveries, and myths and culture related to Mercury. There are also numerous pictures and additional websites to find more information.

2005-06-07

7

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.

8

Mercury  

MedlinePLUS

... mainly by microscopic organisms in the water and soil. More mercury in the environment can increase the ... from manufacturing plants. It enters the water or soil from natural deposits, disposal of wastes, and volcanic ...

9

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.

10

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

11

Vinylmercury Hydrides: Synthesis and Spectroscopic Characterization.  

PubMed

The first vinylmercury hydrides, and among them the parent compound, have been prepared by a chemoselective reduction of the corresponding vinylmercury chlorides with tributylstannane in the presence of a radical inhibitor. These hydrides have been characterized on the basis of their spectral data ((1)H, (13)C, and (199)Hg NMR spectroscopy and mass spectrometry). The photoelectron spectra of the ethenylmercury hydride displays bands at 9.79, 10.13, 11.41, and 13.20 eV. On the basis of photoelectron spectra and ab initio quantum chemical calculations some (d-p)pi interaction between the vinyl pi-system and the mercury d-orbitals could be concluded. Vinylmercury hydrides have been condensed and then revaporized in vacuum at low temperature, but they exhibit a very low stability at room temperature even diluted in toluene (tau(1/2) approximately 1 min); elemental mercury and the corresponding divinylmercury were formed under these conditions. PMID:11666808

Guillemin, Jean-Claude; Bellec, Nathalie; Szétsi, Sándor Kis; Nyulászi, László; Veszprémi, Tamás

1996-10-23

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

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

PubMed

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

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

2011-05-15

14

Stable Hydride Meisenheimer Adducts.  

National Technical Information Service (NTIS)

The addition of hydride from octahydrotriborate ion to 1-substituted-2,4,6-trinitrobenzenes affords a stable C3-hydride Meisenheimer adduct. Concurrent with this addition reaction, is hydride displacement of the C1-substituent to form 1,3,5-trinitrobenzen...

L. A. Kaplan A. R. Siedle

1970-01-01

15

Electrochemical utilization of metal hydrides  

SciTech Connect

The electrochemical utilization of metal hydrides is reviewed. Metal hydrides were investigated for hydrogen storage in nickel hydrogen batteries. The use of hydrides lowered the operating pressures in nickel hydrogen cells, which leads to improved energy density. Metal hydrides used as reversible hydrogen electrodes are discussed. Thermodynamic and kinetic investigations of a variety of hydriding materials are reviewed.

Bittner, H.F.; Badcock, C.C.

1982-04-01

16

Paramagnetic Resonance of Irradiated Lithium Hydride Luminescent Crystals.  

National Technical Information Service (NTIS)

The dependence of the intensity and width of the absorption line of the EPR on temperature was investigated in irradiated lithium hydride luminescent crystals. The irradiation was done at room temperature with the unfiltered light of an SVD-120 mercury la...

B. V. Shulgin F. F. Gavrilov B. I. Dvinyaninov V. I. Koryakov A. K. Chirkov

1968-01-01

17

Hysteresis in Metal Hydrides.  

ERIC Educational Resources Information Center

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

Flanagan, Ted B., And Others

1987-01-01

18

Millimeter-Wave Spectroscopy of Ethylmercury Hydride  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

19

Hydride reorientation in Zircaloy4 cladding  

Microsoft Academic Search

The formation of radial hydrides in stress-relief annealed Zircaloy-4 cladding was studied. Specimens were firstly hydrided to different target hydrogen levels from 100 to 600wtppm and then thermally cycled in an autoclave under a constant hoop stress to form radial hydrides by a hydride reorientation process. The effect of thermal cycling on the hydride reorientation was more significant than that

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

2008-01-01

20

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

1981-01-01

21

Hydrogen Outgassing from Lithium Hydride  

SciTech Connect

Lithium hydride is a nuclear material with a great affinity for moisture. As a result of exposure to water vapor during machining, transportation, storage and assembly, a corrosion layer (oxide and/or hydroxide) always forms on the surface of lithium hydride resulting in the release of hydrogen gas. Thermodynamically, lithium hydride, lithium oxide and lithium hydroxide are all stable. However, lithium hydroxides formed near the lithium hydride substrate (interface hydroxide) and near the sample/vacuum interface (surface hydroxide) are much less thermally stable than their bulk counterpart. In a dry environment, the interface/surface hydroxides slowly degenerate over many years/decades at room temperature into lithium oxide, releasing water vapor and ultimately hydrogen gas through reaction of the water vapor with the lithium hydride substrate. This outgassing can potentially cause metal hydriding and/or compatibility issues elsewhere in the device. In this chapter, the morphology and the chemistry of the corrosion layer grown on lithium hydride (and in some cases, its isotopic cousin, lithium deuteride) as a result of exposure to moisture are investigated. The hydrogen outgassing processes associated with the formation and subsequent degeneration of this corrosion layer are described. Experimental techniques to measure the hydrogen outgassing kinetics from lithium hydride and methods employing the measured kinetics to predict hydrogen outgassing as a function of time and temperature are presented. Finally, practical procedures to mitigate the problem of hydrogen outgassing from lithium hydride are discussed.

Dinh, L N; Schildbach, M A; Smith, R A; Balazs1, B; McLean II, W

2006-04-20

22

PRODUCTION OF LITHIUM HYDRIDE POWDER  

Microsoft Academic Search

A method for the production of lithium hydride powder is described. ; Lithium carbonate was converted into the chloride. From a saturated solution of ; the chloride lithium amalgam was produced by electrolysis. The lithium amalgam ; was then converted into the hydride by heating the amalgam in a hydrogen ; atmosphere. The apparatus used for the reaction of the

J. Novotny; M. Novotna

1959-01-01

23

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

24

[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

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

Bonding of xenon hydrides.  

PubMed

We have computed the structure and stability of the xenon hydrides HXeY (with Y = F, Cl, Br, I, CCH, CN, NC) using relativistic density functional theory (DFT) at ZORA-BP86/TZ2P level. All model systems HXeY studied here are bound equilibrium structures, but they are also significantly destabilized with respect to Xe and HY. We have analyzed the bonding in HXeY in order to arrive at a simple picture that explains the main trends in stability. PMID:19658392

Pérez-Peralta, Nancy; Juárez, Rosalba; Cerpa, Erick; Bickelhaupt, F Matthias; Merino, Gabriel

2009-09-01

27

Bonding of Xenon Hydrides  

NASA Astrophysics Data System (ADS)

We have computed the structure and stability of the xenon hydrides HXeY (with Y = F, Cl, Br, I, CCH, CN, NC) using relativistic density functional theory (DFT) at ZORA-BP86/TZ2P level. All model systems HXeY studied here are bound equilibrium structures, but they are also significantly destabilized with respect to Xe and HY. We have analyzed the bonding in HXeY in order to arrive at a simple picture that explains the main trends in stability.

Pérez-Peralta, Nancy; Juárez, Rosalba; Cerpa, Erick; Bickelhaupt, F. Matthias; Merino, Gabriel

2009-08-01

28

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.

29

Metal hydride heat pump  

NASA Astrophysics Data System (ADS)

The materials, design features, and projected performance of a metal hydride heat pump are explored. Two alloys with hydrogen absorption/desorption (endothermic) properties are included, with the hydrogen being driven back and forth between the two and not consumed. Heat rejected by absorption is rejected by the cold side to the air. When the cold side is full, the pressure differential is reversed and the hydrogen returns to the warm section. Heat in a coolant is used at the cold side to initiate dissociation from the hydride. A test unit providing 3.5.7 kWt of cooling capacity with a source temperature of 200 F and a refrigerated cycle of 40-50 F was built using LaNi5 for the warm side and MMNi4.5FeO.85 on the cold side. Full power was reached in 3-6 min and performance coefficients near .5 were attained. Waste heat, solar and fossil fuel heat sources were identified as viable power supply candidates for refrigeration units requiring 0.5-10.0 tons of capacity.

Rohy, D. A.; Argabright, T. A.; Wade, G. W.

30

Hydrogen storage in metal hydrides  

NASA Astrophysics Data System (ADS)

The use of metal hydrides as a hydrogen-storage medium for hydrogen-powered vehicles is discussed. Various metal hydrides are compared by their hydrogen content and energy density, and their suitability as a storage medium is evaluated against a set of criteria, such as ease of formation and decomposition, availability, cost, and safety. Compounds based on iron-titanium hydride are shown to be practical for use in motor vehicles as well as in other applications, including energy storage for peak leveling in electric power systems, compressors, pumps, and air-conditioners.

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

1980-02-01

31

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

32

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

33

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

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

REMOVAL OF MERCURY FROM COAL-DERIVED SYNTHESIS GAS  

SciTech Connect

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

Tom Barton

2006-03-01

36

Heat Transfer Enhancement in Metal Hydride Systems.  

National Technical Information Service (NTIS)

The Brookhaven National Laboratory, Department of Energy and Environment has been engaged in finding solutions to the engineering problems associated with the storage of hydrogen as metal hydrides - principally iron-titanium hydride. The thermal conductiv...

M. J. Rosso G. Strickland

1979-01-01

37

Hydride reorientation in Zircaloy-4 cladding  

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

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

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

40

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

41

Feasibility of developing a mercury hydride molecular laser  

SciTech Connect

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

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

1985-12-01

42

Mercury banned  

SciTech Connect

This article describes the banning of the use of mercury as a biocide in indoor paints. Mercury will be allowed in outdoor paints but products must be labelled that they contain the metal and must include a warning for outdoor use only. Because mercury can offgas into the environment for several months after a room is painted, exposed individuals may be at risk for kidney disease, neurological impairment, gastrointestinal problems and cardiovascular disorders. Some paint manufacturers feel that the EPA has overreacted to an isolated case in which mercury in paint was found to be responsible for the serious illness of a five-year-old boy. They say that the new mandate will cost the industry an estimated $50 million to mix up-to-code paints, print new labels and test other biocides for efficacy.

Lomuscio, J.

1990-10-01

43

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

44

Synthesis of a novel anionic hydride organosiloxane presenting biochemical properties  

Microsoft Academic Search

Synthesis of an anionic hydride from monomeric silsesquioxanes is described. The novel compound, dubbed “silica hydride” is the first of several newly synthesized compounds from an interstitially embedded hydride family. It is a hydride-based compound with H? ions interstitially embedded in a matrix of caged silica. This compound exhibits profoundly different characteristics than other known compounds in hydride family. Unlike

Cory J Stephanson; G. Patrick Flanagan

2003-01-01

45

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

46

Radon hydrides: structure and bonding.  

PubMed

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

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

2011-02-14

47

THERMOPHYSICAL PROPERTIES OF ZIRCONIUM HYDRIDE  

Microsoft Academic Search

Thermal conductivity values were determined for three Zr--H alloys ; containing 60.0, 56.6, and 45,3 at.% H, A definite negative coefficiert of ; conductivity was observed for the delta hydride (60.0 at.% H) over the test range ; (300 to 720 deg C). The observed conductivities at the lower hydrogen levels are ; discussed in terms of the phases present,

Beck

1962-01-01

48

Ten degree Kelvin hydride refrigerator  

NASA Technical Reports Server (NTRS)

A compact hydride absorption refrigeration system with few moving parts for 10 Kelvin operation is disclosed and comprises liquid hydrogen producing means in combination with means for solidifying and subliming the liquid hydrogen produced. The liquid hydrogen is sublimed at about 10 Kelvin. By using a symmetrical all hydrogen redundant loop system, a 10 Kelvin refrigeration system can be operated for many years with only a fraction of the power required for prior art systems.

Jones, Jack A. (inventor)

1987-01-01

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

Lightweight hydrides for automotive storage of hydrogen  

NASA Astrophysics Data System (ADS)

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

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

52

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.

53

Mercury Calculator  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2010-12-23

54

Sealed aerospace metal-hydride batteries  

Microsoft Academic Search

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

Dwaine Coates

1992-01-01

55

Erbium hydride thermal desorption : controlling kinetics.  

SciTech Connect

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

Ferrizz, Robert Matthew

2007-08-01

56

Mercury in the Environment  

NSDL National Science Digital Library

Through hands-on activities, help your students understand the new EPA regulations on mercury emissions, identify a major human-related source of mercury in the environment and summarize the dangers of mercury in humans.

Jason McGraw (;)

2007-09-25

57

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

58

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

59

Interstellar Hydride Spectroscopy with Herschel  

NASA Astrophysics Data System (ADS)

The Herschel satellite is now giving access with unprecedented sensitivity to the THz spectral range. In particular ground state lines of simple neutral and ionized hydrides have been detected in a wide range of interstellar environments, leading to a renewed understanding of the formation processes of interstellar molecules in the diffuse interstellar medium. In this talk, I will present recent results obtained with the Herschel HIFI and PACS instruments on the carbon, oxygen and nitrogen hydrides. I will discuss how CH and HF can be used as tracers of molecular hydrogen in the diffuse interstellar matter, the new diagnostic capabilities of the cosmic ray ionization rate opened by the OH^+ and H_2O^+ molecular ions, and the role of the dissipation of turbulence in the production of the CH^+ and SH^+ reactive ions. Figure 1: Example of Herschel/HIFI spectra towards the massive star forming region G10.6--0.4. The diffuse interstellar matter along the line of sight towards this massive object is producing multiple absortion features from ˜ 6 to˜ 50 km/s while the emission or absortion signals between -20 to 5 km/s are caused by the massive source itself.

Gerin, Maryvonne

2011-06-01

60

Fabrication of a selective mercury sensor based on the adsorption of cold vapor of mercury on carbon nanotubes: determination of mercury in industrial wastewater.  

PubMed

A new sensor for the determination of mercury at microg ml(-1) levels is proposed based on the adsorption of mercury vapor on single-walled carbon nanotubes (SWCNTs). The changes in the impedance of SWCNTs were monitored upon adsorption of mercury vapor. The adsorption behaviour of mercury on SWCNTs was compared with that on multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs). Cold vapor of mercury was generated at 65 degrees C using Sn(II) solution as a reducing agent. The limit of detection was 0.64 microg ml(-1) for Hg(II) species. The calibration curve for Hg(II) was linear from 1.0 to 30.0 microg ml(-1). The relative standard deviation (RSD) of eight replicate analyses of 15 microg ml(-1) of Hg(II) was 2.7%. The results showed no interfering effects from many foreign species and hydride forming elements. The system was successfully applied to the determination of the mercury content of different types of wastewater samples. PMID:19782468

Safavi, Afsaneh; Maleki, Norouz; Doroodmand, Mohammad Mahdi

2010-01-15

61

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

62

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

63

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

64

Hydride heat pump with heat regenerator  

NASA Technical Reports Server (NTRS)

A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Jones, Jack A. (Inventor)

1991-01-01

65

Study of Titanium Hydride Destabilized Lithium Aluminum Hydride as a Promising Hydrogen Storage System  

NASA Astrophysics Data System (ADS)

Destabilized hydrides are a class of hydrogen storage systems whereby the theoretical hydrogen desorption temperature is reduced owing to the formation of a stable product phase which is typically comprised of cations from the destabilizer and the hydride phase. This work examines the hydrogen desorption temperatures for a mixture of titanium hydride (TiH2) (as a destabilizer) and lithium aluminum hydride (LiAlH4). X-ray diffraction (XRD) and temperature programmed desorption (TPD) were used to confirm the onset of desorption at temperatures as low as 75 deg C. The thermodynamic phase diagram corresponding to the mixed system will be presented and a reaction mechanism is suggested.

Smith, Troy; Dobbins, Tabbetha

2013-03-01

66

Mercury and health care.  

PubMed

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

Rustagi, Neeti; Singh, Ritesh

2010-08-01

67

Thermocompressor or Heat Pump Using Metal Hydrides.  

National Technical Information Service (NTIS)

Metallic hydrides present interesting prospects for use in hydrogen storage and in thermodynamic sorption-desorption cycle machines. First the state of art of work at national and international level are exposed. The technical study leads to the choice of...

M. Blondeau M. Bonneton M. Jannot

1981-01-01

68

Sealed aerospace metal-hydride batteries  

NASA Technical Reports Server (NTRS)

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

Coates, Dwaine

1992-01-01

69

Sealed aerospace metal-hydride batteries  

NASA Astrophysics Data System (ADS)

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

Coates, Dwaine

1992-02-01

70

Method of forming metal hydride films  

NASA Technical Reports Server (NTRS)

The substrate to be coated (which may be of metal, glass or the like) is cleaned, both chemically and by off-sputtering in a vacuum chamber. In an ultra-high vacuum system, vapor deposition by a sublimator or vaporizer coats a cooled shroud disposed around the substrate with a thin film of hydride forming metal which getters any contaminant gas molecules. A shutter is then opened to allow hydride forming metal to be deposited as a film or coating on the substrate. After the hydride forming metal coating is formed, deuterium or other hydrogen isotopes are bled into the vacuum system and diffused into the metal film or coating to form a hydride of metal film. Higher substrate temperatures and pressures may be used if various parameters are appropriately adjusted.

Steinberg, R.; Alger, D. L.; Cooper, D. W. (inventors)

1977-01-01

71

Characterization and Evaluation of Light Metal Hydrides.  

National Technical Information Service (NTIS)

Evaluation of a light metal hydride in CMDB propellants was continued. Distinct improvements in processibility were observed with recent batch production lots. By contrast, the laboratory scale continuous process to-date has produced a material that is mo...

W. E. Baumgartner G. E. Myers W. S. Baker Y. A. Tajima

1967-01-01

72

Modular hydride beds for mobile applications.  

National Technical Information Service (NTIS)

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 inten...

M. E. Malinowski K. D. Stewart

1997-01-01

73

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

PubMed

The millimeter-wave rotational spectrum of an organomercury compound, ethylmercury hydride, has been recorded and assigned for the first time. The spectroscopic study is complemented by quantum chemical calculations taking into account relativistic effects on the mercury atom. The very good agreement between theoretical and experimental molecular parameters validates the chosen ab initio method, in particular its capability to predict accurate quartic centrifugal distortion constants related to this type of compound. Estimations of the nuclear quadrupole coupling constants have less predictive power than those of the structural parameters, but are good enough to satisfy the spectroscopic needs. In addition, the orientation of the axis of the H-Hg-C bonds deduced from the experimental nuclear quadrupole coupling constants compares well with the corresponding ab initio value. From the good agreement between experimental and theoretical results, together with the observation of the six most abundant isotopes of mercury, ethylmercury hydride is unambiguously identified as the product of the chemical reaction described here, and its calculated equilibrium geometry is confirmed. PMID:22587478

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

2012-06-01

74

Mercury Project  

NASA Technical Reports Server (NTRS)

Publicity photograph of a technician measuring a wind tunnel model of the Little Joe test vehicle. Joseph Shortal noted that (vol. 3, p. 29): 'The largest project at Wallops in support of Mercury was the Little Joe project, designed to qualify the abort-escape system under flight conditions.' James Hansen (p. 47) writes: 'STG engineers Max Faget and Paul Purser, then of Langley's PARD, had conceived Little Joe as a space capsule test vehicle even before the establishment of NASA and the formation of the STG. Girlruth understood the importance of the Little Joe tests: 'We had to be sure there were no serious performance and operational problems that we had simply not thought of in such a new and radical type of flight vehicle.'

1959-01-01

75

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

National Technical Information Service (NTIS)

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

B. Hassett-Sipple J. Swartout R. Schoeny

1997-01-01

76

Mercury Contamination of Aquatic Ecosystems  

NSDL National Science Digital Library

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

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

77

Hydride fuel behavior in LWRs  

NASA Astrophysics Data System (ADS)

The U-Zr hydride U 0.31ZrH 1.6 offers a number of advantages over oxide fuel for light-water reactors. Fission-gas release appears to be very small (release fraction ˜10 -4) up to 600 °C, which is close to the maximum fuel temperature. Initial irradiation-induced swelling can be as large as 5% for temperatures exceeding 650 °C. Hydrogen redistributes due to the non-uniform temperature in the fuel from the as-fabricated H/Zr of 1.6 to one that is higher at the pellet periphery than at the centerline. Radial redistribution produces 'hydrogen' stresses in the pellet which add to the usual thermal stresses. In a helium-bonded fuel rod, the total stresses are less than the fracture stress; in a liquid-metal-bonded fuel rod, the fracture stress is exceeded in the central portion of the pellet, but the surface remains in compression. Axial redistribution moves substantial quantities of hydrogen from the middle portion of the fuel stack to the ends. The neutronic effect of this displacement of the moderator is unknown.

Olander, Donald R.; Ng, Marowen

2005-11-01

78

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

79

Determination of mercury by furnace atomic nonthermal excitation spectrometry  

NASA Astrophysics Data System (ADS)

The determination of Hg using different variants of the Furnace Atomic Nonthermal Excitation Spectrometry (FANES) is described. In the direct analysis of micro volumes of solutions, the results could be improved by working with chemical modifiers for the stabilization of Hg during the thermal pretreatment. The best results were obtained using Ir and Pd as modifiers, with absolute detection limits of 4 and 12 pg, respectively. The determination of mercury in sample volumes up to 10 ml could be achieved by coupling a cold vapour generation system and an amalgam attachment to the FANES source. A detection limit of 22 ng/l was obtained with this technique. The best results were obtained by using the cold vapour generation technique and in situ enrichment of Hg onto the modified inner surface of the graphite tube of the FANES source. Using Ir for permanent impregnation of the tube a detection limit of 0.0009 ?;g/l was found. The influence of hydride forming elements on the determination of mercury by the technique of vapour generation and in situ enrichment was studied. A reduction of the concentration of NaBH 4 to 0.002% m/v made it possible to determine traces of mercury in presence of a high excess of hydride forming elements without any depression of the Hg emission intensity. The results were validated using standard reference materials.

Dittrich, K.; Franz, T.; Wennrich, R.

1994-12-01

80

Hydriding of Titanium Cones for a Sputter-Ion Source.  

National Technical Information Service (NTIS)

A technique for producing negative ions of hydrogen, deuterium, tritium from a sputter-ion source by sputtering hydrided titanium in the source. The hydridation of the titanium is described. (ERA citation 03:038387)

J. C. Gursky B. A. Sherwood

1978-01-01

81

Mercury CEM Calibration.  

National Technical Information Service (NTIS)

The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is workin...

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

2007-01-01

82

Mercury's South Polar Region  

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...

83

Mercury: Basic Information  

MedlinePLUS

... generated as byproducts from pollution control activities at gold mines or in waste. Elemental mercury is processed ... Development Organization (UNIDO)'s Global Mercury Project's small-scale gold (artisanal) mining project, which focuses on best management ...

84

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

85

Hydride formation in an Al-Li-Cu alloy  

SciTech Connect

A hydride phase, LiAlH4, is identified in Al-2.0Li-2.2Cu alloy electrochemically charged with hydrogen. The orientation relationship of the hydride and the matrix has been determined and rationalized with the O-lattice theory. The thermodynamic stability of the hydride is discussed and possible formation mechanisms explained. The hydride forms from the grain-boundary phase AlLi. 41 refs.

Balasubramaniam, R.; Duquette, D.J.; Rajan, K. (Rensselaer Polytechnic Institute, Troy, NY (USA))

1991-11-01

86

Investigation of metal hydride nanoparticles templated in metal organic frameworks  

Microsoft Academic Search

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

Benjamin W. Jacobs; Julie L. Herberg; Aaron M. Highley; Jeffrey Grossman; Lucas Wagner; Raghu Bhakta; D. Peaslee; Mark D. Allendorf; X. Liu; Behrens Richard Jr; Eric H. Majzoub

2010-01-01

87

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

88

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...

89

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

90

Mercury environment monitoring  

NASA Astrophysics Data System (ADS)

We report a development of analytical techniques and a portable high selective analyzer for measuring mercury content in the atmosphere, water, soil and biological objects to use them in ecological monitoring and to control technological processes with mercury and the compounds thereof. Provision of mercury monitoring is made from background to maximum permissible concentration (MPC).

Antipov, A. B.; Genina, E. Y.; Melnikov, N. G.; Kashkan, G. V.

1995-10-01

91

Dental amalgam and mercury  

Microsoft Academic Search

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

Mackert; J. R. Jr

1991-01-01

92

Dental amalgam and mercury  

SciTech Connect

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

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

1991-08-01

93

[Mercury emission from the indigenous method of mercury smelting in Wuchuan mercury mining areas, Guizhou Province].  

PubMed

By determining mercury concentrations in mercury ore and smelting slag samples, we used a mass balance method to calculate mercury emission factors and annual mercury emission from the indigenous method of mercury smelting in Wuchuan mercury mining areas, Guizhou Province. The mercury emission factors of the indigenous method ranged from 6.9% to 32.1% with the recovery from 78.4% to 93.6% and the annual mercury emission was up to 3.7-9.6 tons. The results highlighted that the indigenous mercury smelting was one of the most important anthropogenic atmospheric mercury emission sources in this region. PMID:16850818

Li, Ping; Feng, Xin-bin; Qiu, Guang-le; Wang, Shao-feng

2006-05-01

94

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

95

Hydride Reorientation and Delayed Hydride Cracking of Spent Fuel Rods in Dry Storage  

NASA Astrophysics Data System (ADS)

The aim of this work is to investigate the effect of thermal creep during vacuum drying of spent fuel rods on hydride reorientation and their delayed hydride cracking (DHC) susceptibility. To these ends, we analyzed Tsai’s thermal creep results of irradiated Zircaloy-4 cladding segments from two pressurized water reactors and Simpson and Ells’ observation where zirconium alloy cladding tube failed during long-term storage at room temperature. On cooling under 190 MPa, the spent fuel rods crept to 3.5 pct strain during vacuum drying showed large radial hydrides, while the ones crept to 0.35 pct strain had very fine radial hydrides. Thus, it is suggested that prior creep deformation promotes hydride reorientation in spent fuel rods on cooling after vacuum drying. Evidence for this suggestion is provided by a model experiment. Considering Kim’s DHC model and experimental facts showing precipitation of hydrides even at room temperature at stress raisers, we suggest that spent fuel rods would fail by DHC in dry storage if stress raisers are present inside the cladding on cooling to below 180 °C, and then axial splits of the failed spent fuel rods would occur by DHC due to fuel expansion by UO2 oxidation.

Kim, Young S.

2009-12-01

96

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

SciTech Connect

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

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

1994-09-21

97

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

NASA Astrophysics Data System (ADS)

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

Kubo, T.; Kobayashi, Y.

2013-08-01

98

Metal hydride fuel storage and method thereof  

DOEpatents

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

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

2009-05-05

99

Anharmonicity in aluminum hydride at high pressures  

Microsoft Academic Search

Aluminum hydride has been predicted to be a superconductor with a transition temperature of 24 K at 110 GPa, in disagreement with the experimental observation. In this work, it is shown that the bulk of the electron–phonon coupling can be associated with modes that are highly anharmonic according to frozen phonon calculations. This large anharmonicity could partially explain the origin of the

Bruno Rousseau; Aitor Bergara

2011-01-01

100

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

101

Hydride fuel for LWRs—Project overview  

Microsoft Academic Search

This special issue of Nuclear Engineering and Design consists of a dozen papers that summarize the research accomplished in the DOE NERI Program sponsored project NERI 02-189 entitled “Use of Solid Hydride Fuel for Improved Long-Life LWR Core Designs”. The primary objective of this project was to assess the feasibility of improving the performance of pressurised water reactor (PWR) and

E. Greenspan; M. Fratoni; F. Ganda; F. Ginex; D. Olander; N. Todreas; P. Diller; P. Ferroni; J. Malen; A. Romano; C. Shuffler; J. Trant; B. Petrovic; H. Garkisch

2009-01-01

102

Linear solution for hydriding of uranium.  

National Technical Information Service (NTIS)

A set of equations describing the hydriding of solid pieces of uranium is presented, together with an approximate solution of the equations. The solution predicts a constant velocity of the spall front in the solid piece, which leads to a constant value o...

J. R. Kirkpatrick J. B. Condon

1990-01-01

103

Characterization and Evaluation of Light Metal Hydrides.  

National Technical Information Service (NTIS)

Four samples of a light metal hydride produced by bench-scale continuous process could not be processed in LPC-1032B formulations. A higher density material form was found to be more difficult to passivate and subject to attrition with loss of passivation...

W. E. Baumgartner Y. A. Tajima W. S. Baker

1967-01-01

104

SANS Measurement of Hydrides in Uranium  

Microsoft Academic Search

SANS scattering is shown to be an effective method for detecting the presence of hydrogen precipitates in uranium. High purity polycrystalline samples of depleted uranium were given several hydriding treatments which included extended exposures to hydrogen gas at two different pressures at 630 C as well as a furnace anneal at 850 C followed by slow cooling in the near

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

2001-01-01

105

Hydride embrittlement in ZIRCALOY-4 plate; Part 2: Interaction between the tensile stress and the hydride morphology  

SciTech Connect

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

Bai, J.B.; Prioul, C.; Francois, D. (Ecole Centrale Paris, Chatenay-Malabry (France)); Ji, N. (ENSAM, Paris (France)); Gilbon, D. (C.E.N. Saclay, Gif-sur-Yvette (France))

1994-06-01

106

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

107

Mercury Quick Facts: Health Effects of Mercury Exposure  

MedlinePLUS

... The health effects that can be caused by breathing mercury depend on how much mercury vapor you ... is most likely to have health problems after breathing mercury vapors? The following groups of people are ...

108

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

109

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

110

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

111

Mercury's South Pole  

NASA Technical Reports Server (NTRS)

After passing Mercury the first time and making a trip around the Sun, Mariner 10 again flew by Mercury on September 21 at 1:59 PMPDT. This encounter brought the spacecraft in front of Mercury in the southern hemisphere.

In this frame south is down, the south pole is located on the right hand edge of the large crater that has only its rim sticking up into the light (Chao Meng Fu crater). When this frame (FDS 166902) was acquired Mariner 10 was about 83,000 km from Mercury.

The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA/JPL/Northwestern University

1974-01-01

112

Mercury-induced renal effects  

Microsoft Academic Search

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

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

113

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

114

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

115

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

116

Peru Mercury Inventory 2006  

USGS Publications Warehouse

In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in other products such as batteries and computer electronics is not recycled and may ultimately be released to the environment.

Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

2007-01-01

117

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

118

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

119

Metal hydrides for lithium-ion batteries  

Microsoft Academic Search

Classical electrodes for Li-ion technology operate via an insertion\\/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH2 with Li that constitutes the first use of a metal-hydride

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

2008-01-01

120

Preparation of hydride-forming intermetallic films  

Microsoft Academic Search

Amorphous and polycrystalline films of hydride-forming intermetallic compounds (IMCs) have been prepared by vacuum deposition methods. Structure and composition have been investigated by XRD, XPS and by fluorescent X-ray spectroscopy. La-Ni, Pr-Ni and Ni-Zr films have been obtained on water-cooled Cu substrates by magnetron sputtering of intermetallic targets under an Ar atmosphere. Amorphous films with compositions corresponding to PrNi5 and

O. K Alexeeva; A Chistov; V Sumarokov

1995-01-01

121

ToF-SIMS characterization of uranium hydride  

Microsoft Academic Search

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

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

2007-01-01

122

Mechanochemical synthesis of nanostructured chemical hydrides in hydrogen alloying mills  

Microsoft Academic Search

Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg–Fe system, we have successfully synthesized the ternary complex hydride Mg2FeH6 in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron

Z. Wronski; R. A. Varin; C. Chiu; T. Czujko; A. Calka

2007-01-01

123

Thermal Conductivity of Hydride Powders Layers Interacted With Hydrogen  

Microsoft Academic Search

The results of experiments on measurements of reacting with hydrogen hydride beds thermal conductivity coefficient are presented\\u000a in the article. Installation, designs of measuring cell, and experimental technique for measurements of thermal conductivity\\u000a of various hydride layers (including various metal fillers as well) are briefly described. Experiments were carried out with\\u000a use of different hydrides, including LaNi5. Powders with particle

A. I. Solovey; Y. U. I. SHANIN

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

The Nine Planets: Mercury  

NSDL National Science Digital Library

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

Arnett, Bill

132

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...

133

Volatilization of mercury by resting mercury-resistant bacterial cells  

SciTech Connect

The mercuric ion reduction systems encoded by the Hg{sup 2+}inducible mer operon confers bacterial resistance to mercuric ion. The mer A gene product which is a FAD-containing enzyme catalyzes the reduction of Hg{sup 2+} to volatile elemental mercury with the helo of intracellular thiols and NADP as a cofactor Our earlier studies have shown that growing cells of different mercury-resistant bacteria reduce Hg{sup 2+} compounds to Ha(O). We have also shown the effect of thiol compounds and flavins on mercury-degrading enzyme activities in mercury-resistant bacteria. Here we report that resting cells of mercury-resistant bacteria survive in a buffer system for several hours, synthesize inducible mercury-degrading enzymes and volatilize mercury from a mercury-containing buffer system. We know of no information regarding studies of mercury-degrading enzymes in resting mercury-resistant bacterial cells.

Ghosh, S.; Sadhukhan, P.C.; Ghosh, D.K. [Univ. College of Science, Calcutta (India)] [and others] [Univ. College of Science, Calcutta (India); and others

1996-02-01

134

A Study of Magnesium Hydride Thin Film Phase Transition Kinetics Using In-Situ Hydriding\\/Dehydriding  

Microsoft Academic Search

Magnesium is an attractive material for hydrogen storage because it stores an appreciable amount of hydrogen (7.6 wt.%) as magnesium hydride (MgH2), is abundant in the earth's crust and is relatively inexpensive. Understanding of the structural changes and associated kinetics for the magnesium\\/magnesium hydride phase transition is crucial to engineering practical metal hydride hydrogen storage materials involving magnesium. A thin

Stephen Kelly; Raj Kelekar; Hermione Giffard; Bruce Clemens

2007-01-01

135

[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

136

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

SciTech Connect

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

None

2011-12-05

137

Mercury's Dynamic Magnetic Tail  

NASA Technical Reports Server (NTRS)

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

Slavin, James A.

2010-01-01

138

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

139

A nickel metal hydride battery for electric vehicles  

Microsoft Academic Search

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

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

1993-01-01

140

Global change and mercury  

USGS Publications Warehouse

More than 140 nations recently agreed to a legally binding treaty on reductions in human uses and releases of mercury that will be signed in October of this year. This follows the 2011 rule in the United States that for the first time regulates mercury emissions from electricity-generating utilities. Several decades of scientific research preceded these important regulations. However, the impacts of global change on environmental mercury concentrations and human exposures remain a major uncertainty affecting the potential effectiveness of regulatory activities.

Krabbenhoft, David P.; Sunderland, Elsie M.

2013-01-01

141

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.

142

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

143

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

144

Development of nickel-metal hydride cell  

NASA Technical Reports Server (NTRS)

National Space Development Agency of Japan (NASDA) has conducted the research and development (R&D) of battery cells for space use. A new R&D program about a Nickel-Metal Hydride (Ni-MH) cell for space use from this year, based on good results in evaluations of commercial Ni-MH cells in Tsukuba Space Center (TKSC), was started. The results of those commercial Ni-MH cell's evaluations and recent status about the development of Ni-MH cells for space use are described.

Kuwajima, Saburo; Kamimori, Nolimits; Nakatani, Kensuke; Yano, Yoshiaki

1993-01-01

145

Autodissociating Rydberg states of positronium hydride  

NASA Technical Reports Server (NTRS)

Consequences of the nonrelativistic Coulomb Hamiltonian with a fixed proton are considered for positronium hydride (PsH). An optical-potential method and certain simplifying assumptions are used to compute the lowest s-wave resonance parameters on the basis of the /e(+)H(-)/ configuration. Resonance parameters corresponding to a Ps scattering energy of 4.0190 eV and a width of 0.0303 eV are obtained. These results are shown to be in very close agreement with those of previous studies.

Drachman, R. J.

1979-01-01

146

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

147

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) [Martinez, CA; Jankowski, Alan F. (Livermore, CA) [Livermore, CA; Yu, Conrad (Antioch, CA) [Antioch, CA

2010-08-10

148

Nanoindentation measurements of the mechanical properties of zirconium matrix and hydrides in unirradiated pre-hydrided nuclear fuel cladding  

NASA Astrophysics Data System (ADS)

It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium plates have also been reported. In this paper, Young's modulus, hardness and yield stress are measured for each phase, namely zirconium hydrides and matrix, of pre-hydrided nuclear fuel cladding. To this end, nanoindentation tests were performed on ZIRLO samples in as-received state, on a hydride blister and in samples with 150 and 1200 ppm of hydrogen homogeneously distributed along the hoop direction of the cladding. The results show that the measured mechanical properties of the zirconium hydrides and ZIRLO matrix (Young's modulus, hardness and yield stress) are rather similar. From the experimental data, the hydride volume fraction in the cladding samples with 150 and 1200 ppm was estimated and the average mechanical properties were calculated by means of the rule of mixtures. These values were compared with those obtained from ring compression tests. Good agreement between the results obtained by both methods was found.

Rico, A.; Martin-Rengel, M. A.; Ruiz-Hervias, J.; Rodriguez, J.; Gomez-Sanchez, F. J.

2014-09-01

149

Mercury resistance of Staphylococcus aureus  

PubMed Central

Reasons for the accumulation of mercury-resistant strains of Staphylococcus aureus in hospital have been studied. A collection of paired strains, that is staphylococci similar in every respect except sensitivity to mercury salts, was made. Tests were made in an attempt to demonstrate a link between mercury resistance and some other factor which might aid survival, viz. resistance to drying and heat, production of bound coagulase, growth in the presence of sublethal amounts of tetracycline, survival in human blood at 37° C. and uptake by polymorphs at 30° C. and 37° C., development of resistance to antibiotics and competition in mixed cultures. It was not possible to demonstrate any consistent link between mercury resistance and any of these properties. Paper strips impregnated with the mercurial diuretic, Mersalyl, were shown to differentiate between mercury-resistant and -sensitive strains in vitro. Furthermore, development of resistance to mercury by passage in mercuric chloride-broth was demonstrated. It is proposed that mercury resistance has developed as a result of exposure to the mercury ion. Mercurial diuretics have been frequently used in medical and geriatric patients and it is among these that the higher carrier rates of mercury-resistant strains are found even when the local endemic strain is disregarded. In obstetric patients, where mercurials are seldom used, mercury-resistant strains are rare. Nasal carriage of factory workers exposed to mercury products showed that this group is likely to carry resistant or partially resistant strains. ImagesPlate 1

Hall, Barbara M.

1970-01-01

150

Mercury Exposure and Children's Health  

PubMed Central

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

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

2011-01-01

151

Molecular mechanisms triggered by mercury.  

PubMed

Mercury is an ubiquitous environmental toxin that causes a wide range of adverse health effects in humans. Three forms of mercury exist: elemental, inorganic and organic. Each of them has its own profile of toxicity. Exposure to mercury typically occurs by inhalation or ingestion. Mercury can be an indoor air pollutant, however industry emission remains the most important source of inhaled mercury. Furthermore, fresh water and ocean fish may contain large amounts of mercury and dental amalgam can be another important source of inorganic and mercury vapor. The present review discusses the current information on mercury toxicity and the distinct toxicologic profile of the three forms of mercury. The existing therapeutics, new therapeutics development or agents for treating mercury poisoning will also discussed. Since in general low levels of mercurial are tolerable, herein, we also discuss the defensive mechanisms developed by the cell to protect itself against mercury injury. This aspect may be useful to provide a biological protection against toxic effects exerted by mercury or by specific forms of mercury in view of a medicinal purposes. PMID:18077077

Guzzi, GianPaolo; La Porta, Caterina A M

2008-02-01

152

The tectonics of Mercury  

NASA Technical Reports Server (NTRS)

The probable tectonic history of Mercury and the relative sequence of events are discussed on the basis of data collected by the Mariner-10 spacecraft. Results indicate that Mercury's tectonic activity was confined to its early history; its endogenic activity was principally due to a small change in the shape of its lithosphere, caused by tidal despinning, and a small change in area caused by shrinkage due to cooling. Exogenic processes, in particular the impact activity, have produced more abundant tectonic features. Many features associated with the Caloris basin are due to loading of Mercury's thick lithosphere by extrusive lavas or subsidence due to magma withdrawal. It is emphasized that tectonic features observed on Mercury yield insight into the earliest tectonic events on planets like Mars and, perhaps, the earth, where subsequent events obscured or erased the most ancient tectonic records.

Melosh, H. J.; Mckinnon, W. B.

1988-01-01

153

Mercury's Caloris Basin  

NASA Technical Reports Server (NTRS)

Mercury: Computer Photomosaic of the Caloris Basin

The largest basin on Mercury (1300 km or 800 miles across) was named Caloris (Greek for 'hot') because it is one of the two areas on the planet that face the Sun at perihelion.

The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet.

The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

2001-01-01

154

Method for Scavenging Mercury.  

National Technical Information Service (NTIS)

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 ...

N. Yan S. Chang S. Liu Z. Liu

2005-01-01

155

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

156

Cutaneous mercury granuloma  

PubMed Central

Cutaneous mercury granuloma is rarely encountered. Clinically it may pose difficulty in diagnosis. Here, we report a 23-year-old male presented with erythematous, nodular lesions over the forearm and anterior aspect of chest wall. Metallic mercury in tissue sections appear as dark black, opaque, spherical globules of varying size and number. They are surrounded by granulomatous foreign-body reaction. It is composed of foreign body giant cells and mixed inflammatory infiltrate composed of histiocytes, lymphocytes, plasma cells, and few eosinophils.

Bothale, Kalpana A.; Mahore, Sadhana D.; Pande, Sushil; Dongre, Trupti

2013-01-01

157

[Mercury and Alzheimer's disease].  

PubMed

Higher mercury concentrations were found in brain regions and blood of some patients with Alzheimer's disease (AD). Low levels of inorganic mercury were able to cause AD- typical nerve cell deteriorations in vitro and in animal experiments. Other metals like zinc, aluminum, copper, cadmium, manganese, iron, and chrome are not able to elicit all of these deteriorations in low levels, yet they aggravate the toxic effects of mercury (Hg). Main human sources for mercury are fish consumption (Methyl-Hg) and dental amalgam (Hg vapour). Regular fish consumption reduces the risk of development of AD. Amalgam consists of approx. 50 % of elementary mercury which is constantly being vaporized and absorbed by the organism. Mercury levels in brain tissues are 2 - 10 fold higher in individuals with dental amalgam. Persons showing a genetically determined subgroup of transportation protein for fats (apolipoprotein E4) have an increased AD risk. Apoliprotein E (APO E) is found in high concentrations in the central nervous system. The increased AD risk through APO E4 might be caused by its reduced ability to bind heavy metals. Latest therapeutic approaches to the treatment of Alzheimer disease embrace pharmaceuticals which remove or bind metals from the brain. Preliminary success has been documented with chelation of synergistic toxic metals (Fe, Al, Zn, Cu) and therefore also Hg. The available data does not answer the question, whether mercury is a relevant risk factor in AD distinctively. In sum, the findings from epidemiological and demographical studies, the frequency of amalgam application in industrialized countries, clinical studies, experimental studies and the dental state of Alzheimer patients in comparison to controls suggest a decisive role for inorganic mercury in the etiology of Alzheimer's disease. Other factors currently discussed as causes (e. g. other metals, inflammations, dietetic factors, vitamin deficiency, oxidative distress, and metabolic impairments) may act as co-factors. PMID:17628833

Mutter, J; Naumann, J; Schneider, R; Walach, H

2007-09-01

158

Metal hydrides for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

159

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.

160

Mercury exposure and public health.  

PubMed

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

Clifton, Jack C

2007-04-01

161

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.

162

Release of Mercury from Broken Fluorescent Bulbs  

Microsoft Academic Search

Mercury is a persistent, bioaccumulative toxin. Although the primary human exposure is from ingestion of fish contaminated with methyl mercury (HgCH3 ), exposures to elemental mercury vapor and mercury compounds via inhalation and dermal contact may also occur. Fluorescent bulbs contain mercury. Estimates of the amount of this mercury released when the bulbs are discarded and broken have varied widely.A

Michael Aucott; Michael McLinden; Michael Winka

2003-01-01

163

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

164

MASS: Mercury Amalgamation Stabilization\\/Solidification  

Microsoft Academic Search

Traditionally, cement has not stabilized mercury well. Mercury Amalgamation Stabilization\\/Solidification (MASS) overcomes this limitation through the use of a cement matrix capable of stabilizing soluble mercury compounds and amalgamating-stabilizing agents that also stabilize elemental mercury. The combination of this matrix and these agents not only stabilizes elemental mercury and its compounds but also suppresses the vapor pressure of elemental mercury.

Roger Spence

165

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

166

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

167

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

168

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

169

Investigating the recycling of nickel hydride battery scrap  

NASA Astrophysics Data System (ADS)

New nickel hydride alloys have been developed to replace the cadmium-containing negative electrodes of nickel-cadmium batteries. The new, cadmium free alloys promise enhanced electrochemical properties as well as reduced environmental toxicity. Rechargeable batteries using nickel hydride electrodes are strong candidates for electric vehicle applications. The U.S. Bureau of Mines is investigating hydrometallurgical technology that separates and recovers purified metallic components present in nickel hydride battery scrap. A preliminary investigation of acid dissolution and metal recovery techniques using whole batteries and electrode rolls has shown potential options that will allow the successful recycling of much of the battery fabrication scrap.

Lyman, Jane W.; Palmer, Glenn R.

1993-05-01

170

Technical and economic aspects of hydrogen storage in metal hydrides  

NASA Technical Reports Server (NTRS)

The recovery of hydrogen from such metal hydrides as LiH, MgH2, TiH2, CaH2 and FeTiH compounds is studied, with the aim of evaluating the viability of the technique for the storage of hydrogen fuel. The pressure-temperature dependence of the reactions, enthalpies of formation, the kinetics of the hydrogen absorption and desorption, and the mechanical and chemical stability of the metal hydrides are taken into account in the evaluation. Economic aspects are considered. Development of portable metal hydride hydrogen storage reservoirs is also mentioned.

Schmitt, R.

1981-01-01

171

(Mercury as an environmental pollutant)  

SciTech Connect

The traveler attended the conference Mercury as an Environmental Pollutant'' and presented a technical poster entitled Biotransformations of Mercury in Contaminated and Control Streams in Relation to the Abundance of Microbial Gene Sequences Encoding Mercury Resistance.'' Although a great deal of the subject matter of the conference dealt with the biogeochemical cycling of mercury in aquatic and terrestrial systems which have not been subjected directly to industrial pollution, several presentations addressed contamination scenarios similar to those at the Oak Ridge site. These included one presentation concerning application of ion exchange resins in the treatment of mercury-contaminated wastewater and soil, and several concerning the role of mercury-resistant bacteria in biotransformations of mercury at contaminated sites. The Swedish experience with various methods of treating lakes to reduce mercury in fish was the subject of several presentations and one field trip.

Turner, R.R.

1990-06-28

172

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

173

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

174

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

175

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 ...

176

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...

177

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...

178

Boron hydride analogues of the fullerenes  

SciTech Connect

The BH moiety is isoelectronic with C. We have studied the stability of the (BH)[sub 60] analogue of the C[sub 60] fullerene as well as the dual-structure (BH)[sub 32] icosahedron, both of them being putative structures, by performing local-density-functional electronic calculations. To aid in our analysis, we have also studied other homologues of these systems. We find that the latter, i.e., the dual structure, is the more stable although the former is as stable as one of the latter's lower homologues. Boron hydrides, it seems, naturally form the dual structures used in algorithmic optimization of complex fullerene systems. Fully relaxed geometries are reported as well as electron affinities and effective Hubbard [ital U] parameters. These systems form very stable anions and we conclude that a search for BH analogues of the C[sub 60] alkali-metal supeconductors might prove very fruitful.

Quong, A.A. (Sandia Livermore National Laboratory, Livermore, California 94551-0969 (United States)); Pederson, M.R.; Broughton, J.Q. (Naval Research Laboratory, Washington, D.C. 20375 (United States))

1994-08-15

179

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

180

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

181

Thermally unstable hydrides of titanium aluminide Ti3Al  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

182

Direct observation of hydrides formation in cavity-grade niobium  

NASA Astrophysics Data System (ADS)

Niobium is an important technological superconductor used to make radio frequency cavities for particle accelerators. Using laser confocal microscopy we have directly investigated hydride precipitates formation in cavity-grade niobium at 77 and 140 K. We have found that large hydrides were usually formed after chemical or mechanical treatments, which are known to lead to a strong degradation of the quality factor known as Q disease. From our experiments we can conclude that hydrides causing Q disease are islands with a characteristic thickness of ?100nm and in-plane dimensions 1-10?m. Our results show that mechanical polishing uploads a lot of hydrogen into bulk niobium while electropolishing leads to a mild contamination. Vacuum treatments at 600-800°C are demonstrated to preclude large hydride formation in line with the absence of Q disease in similarly treated cavities.

Barkov, F.; Romanenko, A.; Grassellino, A.

2012-12-01

183

Metal Hydride Preheater for the M2 Diesel Burner.  

National Technical Information Service (NTIS)

This report describes the results of a Phase I Small Business Innovative Research (SBIR) project to demonstrate the feasibility of preheating the catalytic generator of the M2 diesel burner using a metal hydride preheater. Preliminary testing of an electr...

J. Gerstmann M. Golben

1999-01-01

184

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

185

Life test results of hydride compressors for cryogenic refrigerators  

NASA Technical Reports Server (NTRS)

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

186

Materials science of Mg-Ni-based new hydrides  

NASA Astrophysics Data System (ADS)

One of the advantageous functional properties of Mg alloys (or compounds) is to exhibit the reversible hydriding reaction. In this paper, we present our systematic studies regarding the relationship between nanometer- or atomistic-scale structures and the specific hydriding properties of the Mg-Ni binary system, such as(1) nanostructured (n)-Mg2Ni, (2) a mixture of n-Mg2Ni and amorphous (a)-MgNi,(3) pure a-MgNi, and(4) n-MgNi2. Further studies on(5) an a-MgNi-based system for clarifying the effect of the short-range ordering on the structural and hydriding properties and(6) a MgNi2-based system for synthesizing the new Laves phase structure are also presented. The materials science of Mg-Ni-based new hydrides will provide indispensable knowledge for practically developing the Mg alloys as hydrogen-storage materials.

Orimo, S.; Fujii, H.

2001-04-01

187

Neutron diffraction studies of transition metal hydrides and chemistry of metal hydride clusters  

NASA Astrophysics Data System (ADS)

In this dissertation we start by presenting a survey of single-crystal neutron diffraction results on molecular transition metal hydrides. Powder neutron diffraction results from stoichiometric ternary (solid state) hydrides which contain transition metal coordination complexes in their structures are also reviewed. Tabulations of all known neutron diffraction transition metal-hydrogen distances from both the molecular compounds and the ternary hydrides are summarized in the first chapter. In the second chapter, we describe the main achievement of our doctoral research, the discovery of five-coordinate hydrogen via the single-crystal neutron diffract on analysis of the cluster complex (NMesb4rbracksb3(Rhsb{13}Hsb2(CO)sb{24}rbrack*(Me)CO(Et). This work definitively shows that both hydrides in the (Rhsb{13}Hsb2(CO)sb{24}rbracksp{3-} anion are located in square pyrmaidal cavities. The shortest Rh-H bonds are those involving the central Rh atom, 1.827(2)A and 1.861(2)A, while the surface Rh-H bond length average is 1.975(2)A. A large number of crystallizations of the related trihydride cluster (Rhsb{13}Hsb3(CO)sb{24}rbracksp{2-} anion were also set up, of which two yielded crystals suitable for data collection. The x-ray analysis of the ((Phsb3PCHsb2)sb2Csb6Hsb4rbracksp{2+} salt shows the same Rhsb{13} cage and pattern of bridging CO ligands as all previous (Rhsb{13}Hsbn(CO)sb{24}rbracksp(5-n)- (n = 1,2,3) structures. Ligand exchange reactions with phosphines were tried with the (Rhsb{13}Hsb{3}(CO)sb{24}rbracksp{2-} cluster; (Phsb2PCHsb2)sb2, P(cyclohexyl)Phsb2, and P(Csb6Fsb5)sb3 appeared to add successfully. Syntheses of both (Rhsb{13}Hsb1(CO)sb{24}rbracksp{4-} and (Rhsb{13}Hsb4(CO)sb{24}rbracksp- were attempted but did not yield acceptable products. The (Nisb9Ptsb3H(CO)sb{24}rbracksp{3-} anion was synthesized, but crystallization attempts yielded only powders. Attempts to dissolve and crystallize some ternary hydrides are also briefly mentioned. In the final chapter, the neutron diffraction analysis of (K(18-crown-6)) ((PPhsb3)sb2ReHsb6Cr(CO)sb3rbrack is described. The results of this structure determination revealed three hydrides bridging the Re-Cr bond and three terminal hydrides bound to Re. This compound can be described as a donor-acceptor complex, in which the bridging Re-H bonds of ((PPhsb3)sb2ReHsb6rbracksp- act as donors to the Cr(CO)sb3 fragment. Based on a comparison of the Re-musb2H and Cr-musb2H distances with those previously measured, as well as comparisons to the other known M-H donor-acceptor complexes, ((PPhsb3)sb2ReHsb6Cr(CO)sb3rbracksp- is found to be a weak donor-acceptor complex. The Re-Cr separation in ((PPhsb3)sb2ReHsb6Cr(CO)sb3rbracksp- is shorter than previously-determined values for Re-Cr bonds, suggesting that the Re-Cr interaction is strong.

Drabnis, Mary Helen

188

Observations of Mercury’s Exosphere from MESSENGER: An Overview  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

189

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

190

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

191

Mercury's Southern Hemisphere  

NASA Technical Reports Server (NTRS)

Mercury: Computer Photomosaic of the Southern Hemisphere

The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet.

The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

2001-01-01

192

Electronic Structures of Zirconium Hydride and Hydrogen Solid Solution  

Microsoft Academic Search

Electronic structures of zirconium hydride and hydrogen solid solution have been evaluated by the X?ray photoelec- tron spectroscopy andrst-principles molecular orbital calculation. From the valence band spectra of the solid zirconium hydride, the occurrence of the valence electron transfer from Zr 4d band to Zr?H bonding state was found to induce the reduction of Zr?Zr metallic bonds with increasing the

Takanori NISHIZAKI; Shinsuke YAMANAKA

193

Solid-state gadolinium{endash}magnesium hydride optical switch  

SciTech Connect

The optical switching properties of gadolinium{endash}magnesium hydride have been demonstrated in a solid-state electrochromic device. With positive polarization of the hydride electrode, the visible reflectance approaches 35{percent} with virtually zero transmission, while with negative polarization, the visible transmission exceeds 25{percent} at 650 nm. The switching is reversible, with intermediate optical properties between the transparent and reflecting states. {copyright} {ital 1999 American Institute of Physics.}

Armitage, R. [Lawrence Berkeley National Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States); Rubin, M.; Richardson, T. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); OBrien, N. [Optical Coating Laboratory, Inc., 2789 Northpoint Parkway, Santa Rosa, California 95407 (United States)] [Optical Coating Laboratory, Inc., 2789 Northpoint Parkway, Santa Rosa, California 95407 (United States); Chen, Y. [Hewlett-Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94304 (United States)] [Hewlett-Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94304 (United States)

1999-09-01

194

Sonochemical synthesis of copper hydride (CuH).  

PubMed

We report the sonochemical synthesis of copper(I) hydride (CuH) by the ultrasonic irradiation of a copper(II) aqueous solution. A reaction mechanism based on the reduction of copper(II) by the ultrasound-generated hydrogen atoms is discussed. To the best of our knowledge, this is the first time that a metal hydride has been synthesized through sonochemistry. PMID:22179137

Hasin, Panitat; Wu, Yiying

2012-01-30

195

ZIRCONIUM IRON DISPROPORTIONATION DURING HYDRIDING REACTIONS IN NUCLEAR GETTERING OPERATIONS  

Microsoft Academic Search

We have investigated the hydriding properties of Zr2Fe and Zr3Fe alloys, including SAES Getters St-198. It was found from examining the X-ray diffraction patterns of alloys hydrided at temperatures ranging from 303 K to 773 K that disproportionation occurs in the Zr2Fe alloys at temperatures above 673 K. In Zr3Fe the temperature at which disproportionation takes place is much lower

Michael Coleman; Dhanesh Chandra; Joseph Wermer; Terrence J. Udovic

196

C?H Bond Functionalization through Intramolecular Hydride Transfer.  

PubMed

Known for over a century, reactions that involve intramolecular hydride-transfer events have experienced a recent resurgence. Undoubtedly responsible for the increased interest in this research area is the realization that hydride shifts represent an attractive avenue for C?H bond functionalization. The redox-neutral nature of these complexity-enhancing transformations makes them ideal for sustainable reaction development. This Review summarizes recent progress in this field while highlighting key historical contributions. PMID:24706531

Haibach, Michael C; Seidel, Daniel

2014-05-12

197

Sodium Winds on Mercury  

NASA Astrophysics Data System (ADS)

We used the Main Spectrograph at the McMath-Pierce Solar Telescope at KPNO to measure the profile of sodium emission lines from Mercury with a spectral dispersion of 2.8 mA/pixel. An iodine vapor absorption cell and atmospheric absorption lines were used to define the wavelength scale. At the time of measurement (3 and 4 February 2000), Mercury was east of the Sun, with a phase of 20 degrees, so that most of the planetary surface seen from Earth was illuminated by sunlight. The spectrograph slit was oriented north-south on Mercury for one set of observations (3 February), and east-west for another (4 February). After subtraction of scattered sunlight and Mercury surface reflection backgrounds, the wavelength of the centroid for the emission line was measured as a function of position on the spectrograph slit. We found that the wavelength of the sodium centroid differed from the rest wavelength of sodium (taking into account the relative velocities of Earth and Mercury), and varied with position on the planet. Near the Mercury center, the radial velocity of sodium was in the range 0.3-0.4 km/sec towards the Earth. For the east-west transect, the radial velocity towards the Earth increased near the dawn terminator, and decreased towards the dusk terminator. This suggests that there was a flow of sodium vapor from the dawn to the dusk terminators. For the north-south transect, the radial velocity towards the Earth decreased above both poles, suggesting that radiation pressure was pushing sodium off the planet. This work was supported by the NASA Planetary Astronomy Program

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

2000-10-01

198

Control of mercury pollution.  

PubMed

When a 203Ng(NO3)2 solution was kept at 25 degrees C in glass or polypropylene containers, 50 and 80% of original radioactivity was adsorbed to the containers' walls after 1 and 4 days, respectively. However, no loss in radioactivity was observed if the solution was supplemented with HgCl as carrier (100 mug Hg2+/ml) and stored in either container for 13 days. When 203Hg2+ was dissolved in glucose basal salt broth with added carrier, levels of 203Hg2+ in solution (kept in glass) decreased to 80 and 70% of original after 1 and 5 days and decreased even more if stored in polypropylene (60 and 40% of original activity after 1 and 4 days, respectively). In the absence of carrier, decreases of 203Hg2+ activities in media stored in either container were more pronounced due to chemisorption (but) not diffusion. The following factors affecting the removal of mercurials from aqueous solution stored in glass were examined: type and concentration of adsorbent (fiber glass and rubber powder); pH; pretreatment of the rubber; and the form of mercury used. Rubber was equally effective in the adsorption of organic and inorganic mercury. The pH of the aqueous 203Hg2+ solution was not a critical factor in the rate of adsorption of mercury by the rubber. In addition, the effect of soaking the rubber in water for 18 hr did not show any statistical difference when compared with nontreated rubber. It can be concluded that rubber is a very effective adsorbent of mercury and, thus, can be used as a simple method for control of mercury pollution. PMID:1549

Noyes, O R; Hamdy, M K; Muse, L A

1976-01-01

199

Cutaneous mercury granuloma.  

PubMed

Cutaneous mercury granuloma is rarely encountered. Clinically it may pose difficulty in diagnosis. Here, we report a 23-year-old male presented with erythematous, nodular lesions over the forearm and anterior aspect of chest wall. Metallic mercury in tissue sections appear as dark black, opaque, spherical globules of varying size and number. They are surrounded by granulomatous foreign-body reaction. It is composed of foreign body giant cells and mixed inflammatory infiltrate composed of histiocytes, lymphocytes, plasma cells, and few eosinophils. PMID:24082644

Bothale, Kalpana A; Mahore, Sadhana D; Pande, Sushil; Dongre, Trupti

2013-01-01

200

Mercury Transport in Bacteria  

Microsoft Academic Search

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

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

2007-01-01

201

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

202

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

203

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

204

Hydride absorption refrigerator system for ten Kelvin and below  

NASA Astrophysics Data System (ADS)

A very long-life, lightweight and efficient hydride absorption refrigerator system was built to operate at ten Kelvin and below. The system consists of four basic stages of refrigeration. The first stage is accomplished by an active refrigeration system. The second stage is operated by a hydride absorption system, wherein a heated hydride powder drives off high pressure hydrogen through a Joule-Thomson/heat exchanger expansion loop such that the hydrogen is partially liquefied. In the third stage, the vapor pressure over the collected liquid hydrogen is lowered by absorbing the hydrogen vapor onto a different low pressure, worn hydride. With a 1.7 torr partial pressure of hydrogen gas in the hydride, liquid hydrogen is solidified and sublimes at 10 K. Long-life adiabatic demagnetization refrigerators, helium desorption, or helium diaphragm compressors are used to cool to 4 K or below. It is shown that the hydride concepts provide an extremely efficient means of refrigeration to 10 K, and that an entire sorption refrigeration process can be accomplished solely by using low grade heat energy at about 150 C.

Jones, J. A.

1985-05-01

205

Interaction between selenium and inorganic mercury.  

PubMed Central

Data on mercury and selenium interaction in the mammalian body are reviewed. Experimental data from studies on rats show that selenium interacts with mercury metabolism and toxicity after exposure to mercuric mercury. Autopsy data from workers exposed to mercury vapor indicate an association between mercury and selenium retention in the central nervous system, suggesting the formation of a mercury-selenium complex. In animal experiments, mercuric mercury interferes with selenium metabolism and toxicity. Available data do not, at present, permit deduction as to whether additional selenium intake in man, exposed to mercury vapor or mercuric mercury, will have any effect, beneficial or adverse.

Berlin, M

1978-01-01

206

Trialkylborane-Assisted CO2 Reduction by Late Transition Metal Hydrides  

PubMed Central

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

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

2011-01-01

207

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

208

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

209

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

210

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 ...

211

Mercury's South Pole  

NASA Technical Reports Server (NTRS)

Mercury's south pole was photographed by one of Mariner 10's TV cameras as the spacecraft made its second close flyby of the planet September 21. The pole is located inside the large crater (180 kilometers, 110 miles) on Mercury's limb (lower center). The crater floor is shadowed and its far rim, illuminated by the sun, appears to de disconnected from the edge of the planet. Just above and to the right of the South Pole is a double ring basin about 100 kilometers (125 miles) in diameter. A bright ray system, splashed out of a 50 kilometer (30 mile) crater is seen at upper right. The stripe across the top is an artifact introduced during computer processing. The picture (FDS 166902) was taken from a distance of 85,800 kilometers (53,200 miles) less than two hours after Mariner 10 reached its closest point to the planet.

The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA/JPL/Northwestern University

1974-01-01

212

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...

213

Mercury CEM Calibration  

Microsoft Academic Search

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)

John Schabron; Joseph Rovani; Mark Sanderson

2008-01-01

214

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

215

Mercury Shopping Cart Interface  

NASA Technical Reports Server (NTRS)

Mercury Shopping Cart Interface (MSCI) is a reusable component of the Power User Interface 5.0 (PUI) program described in another article. MSCI is a means of encapsulating the logic and information needed to describe an orderable item consistent with Mercury Shopping Cart service protocol. Designed to be used with Web-browser software, MSCI generates Hypertext Markup Language (HTML) pages on which ordering information can be entered. MSCI comprises two types of Practical Extraction and Report Language (PERL) modules: template modules and shopping-cart logic modules. Template modules generate HTML pages for entering the required ordering details and enable submission of the order via a Hypertext Transfer Protocol (HTTP) post. Shopping cart modules encapsulate the logic and data needed to describe an individual orderable item to the Mercury Shopping Cart service. These modules evaluate information entered by the user to determine whether it is sufficient for the Shopping Cart service to process the order. Once an order has been passed from MSCI to a deployed Mercury Shopping Cart server, there is no further interaction with the user.

Pfister, Robin; McMahon, Joe

2006-01-01

216

Atlas of Mercury  

Microsoft Academic Search

The Mariner 10 spacecraft, its scientific mission, and surface mapping techniques are described as well as the topographic features of the planet Mercury as photographed by television cameras during three flyby encounters. Shaded relief maps and a computer generated photomosaic of 9 of the 15 cartographic regions are presented. Subsequent material in the atlas includes enlargements of portions of the

M. E. Davies; S. E. Dornik; D. E. Gault; R. G. Strom

1978-01-01

217

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

218

Elemental mercury spills.  

PubMed

Sources of elemental mercury (Hg0) include old natural gas regulators, manometers, sphygmomanometers, thermometers, and thermostats. Causes of Hg0 spills include improper storage, container breakage, children playing with Hg0, the breakage of devices containing Hg0, and ritualistic use of Hg0. Inhalation is the primary exposure route for Hg0. Mercury released into the environment can enter lakes and streams, where bacteria convert it into methylmercury, which bioaccumulates in fish. Chronic exposure to Hg0 vapors can damage the kidneys and neurologic system. Short-term exposure to high levels of Hg0 vapors may cause lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation, among other effects. Minimizing Hg0 dispersal is important after an Hg0 spill. Tracking by shoes or apparel or vacuuming can spread Hg0, increasing airborne concentrations and cleanup costs. The Illinois Department of Public Health's response to an Hg0 spill depends on the size of the spill. Airborne concentrations after large spills are mapped with a mercury vapor analyzer (MVA). The cleanup begins with the spill site and any hot spots that were identified with the MVA. Hard surfaces can usually be cleaned, but contaminated porous items must be discarded. Leaving marginally contaminated items outdoors for a month or more during warm weather may dissipate the Hg0. After a cleanup, clearance sampling is conducted to determine if further cleanup is needed. The best way to prevent Hg0 spills is reduce its use. Key words: cleanup, elemental mercury, health effects, mercury, prevention, remediation, spill, spill management. PMID:16451846

Baughman, Thomas A

2006-02-01

219

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

220

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, ...

221

Computational modelling of the volatile hydride fragmentation in a dielectric barrier discharge atomizer.  

PubMed

In this study, we present a model whereby a fragmentation of arsenic hydride in a rectangular dielectric barrier discharge (DBD) atomizer is investigated. The aim is to elucidate the distribution of the intermediates species and generated free analyte atoms along atomizer channel, which is required to decide the optimal position for spectrometric data acquisition. Simulation results indicate that formation of intermediate species and free arsenic atoms is initiated in the first section of atomization channel before reaching the section between the electrodes. Moreover, concentration of free arsenic atoms saturates to a maximum and does not vary thereafter along atomization channel. This result could be attributed to the presence of abundance of hydrogen radicals along atomization channel which limits recombination reactions and ultimately maintains free atom life, which is so useful for analytical purposes. This outcome suggests an approach for radial data acquisition from any position along DBD atomization channel with same sensitivity. Furthermore, this result indicates that DBD atomizer is appropriate for analytical purposes and competitive to other well known atomization tools such as a quartz cell atomizer. The model has been verified experimentally upon examining arsenic and mercury qualitatively from applying chemical vapour generation techniques. Approximately similar results obtained from three radial positions along the atomization channel, whereas a significant increase in signal intensity observed when applying axial viewing by 22 and 40% for arsenic and mercury respectively. Furthermore, a quantitative determination for arsenic is also tried; however, the results were found not useful for model validation due to the hydrogen magnification effect on the recorded spectrum. PMID:23173925

Abdul-Majeed, Wameath S; Zimmerman, William B

2013-03-01

222

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...

223

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...

224

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...

225

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

226

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

227

Hydrides of DyCo/sub 3/  

SciTech Connect

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

Kierstead, H.A.

1980-01-01

228

Investigation of Cracked Lithium Hydride Reactor Vessels  

SciTech Connect

Visual examination of lithium hydride reactor vessels revealed cracks that were adjacent to welds, most of which were circumferentially located in the bottom portion of the vessels. Sections were cut from the vessels containing these cracks and examined by use of the metallograph, scanning electron microscope, and microprobe to determine the cause of cracking. Most of the cracks originated on the outer surface just outside the weld fusion line in the base material and propagated along grain boundaries. Crack depths of those examined sections ranged from {approximately}300 to 500 {micro}m. Other cracks were reported to have reached a maximum depth of 1/8 in. The primary cause of cracking was the creation of high tensile stresses associated with the differences in the coefficients of thermal expansion between the filler metal and the base metal during operation of the vessel in a thermally cyclic environment. This failure mechanism could be described as creep-type fatigue, whereby crack propagation may have been aided by the presence of brittle chromium carbides along the grain boundaries, which indicates a slightly sensitized microstructure.

bird, e.l.; mustaleski, t.m.

1999-06-01

229

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

230

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

231

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 ...

232

21 CFR 872.3700 - Dental mercury.  

Code of Federal Regulations, 2010 CFR

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

2009-04-01

233

21 CFR 872.3700 - Dental mercury.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

234

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

235

Chinese puzzle molecule: a 15?hydride, 28?copper atom nanoball.  

PubMed

The syntheses of the first rhombicuboctahedral copper polyhydride complexes [Cu28 (H)15 (S2 CNR)12 ]PF6 (NR=N(n) Pr2 or aza-15-crown-5) are reported. These complexes were analyzed by single-crystal X-ray and one by neutron diffraction. The core of each copper hydride nanoparticle comprises one central interstitial hydride and eight outer-triangular-face-capping hydrides. A further six face-truncating hydrides form an unprecedented bridge between the inner and outer copper atom arrays. The irregular inner Cu4 tetrahedron is encapsulated within the Cu24 rhombicuboctahedral cage, which is further enclosed by an array of twelve dithiocarbamate ligands that subtends the truncated octahedron of 24?sulfur atoms, which is concentric with the Cu24 rhombicuboctahedron and Cu4 tetrahedron about the innermost hydride. For these compounds, an intriguing, albeit limited, H2 evolution was observed at room temperature, which is accompanied by formation of the known ion [Cu8 (H)(S2 CNR)6 ](+) upon exposure of solutions to sunlight, under mild thermolytic conditions, and on reaction with weak (or strong) acids. PMID:24803070

Edwards, Alison J; Dhayal, Rajendra S; Liao, Ping-Kuei; Liao, Jian-Hong; Chiang, Ming-Hsi; Piltz, Ross O; Kahlal, Samia; Saillard, Jean-Yves; Liu, C W

2014-07-01

236

Anthropogenic mercury emissions in China  

Microsoft Academic Search

An inventory of mercury emissions from anthropogenic activities in China is compiled for the year 1999 from official statistical data. We estimate that China's emissions were 536 (±236)t of total mercury. This value includes open biomass burning, but does not include natural sources or re-emission of previously deposited mercury. Approximately 45% of the Hg comes from non-ferrous metals smelting, 38%

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

2005-01-01

237

Mercury Toolset for Spatiotemporal Metadata  

Microsoft Academic Search

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

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

2010-01-01

238

Mercury vapor determination in hospitals.  

PubMed

The measurements of metallic mercury vapor were carried out in seven local hospitals, where mercury-containing products are widely used, as well as in one residence to check effectiveness of decontamination after mercury spillage. Hopcalite as a solid sorbent was used in active and passive sampling methods, and mercury was analyzed by CV-AAS technique. Good agreement was found between results of mercury measurements using active samplers (pumped hopcalite adsorption tubes) and passive (diffusion) monitors applied in indoor atmosphere. The results indicated the presence of metallic mercury vaporization sources in the assessed hospital rooms but in the majority of cases mercury levels did not exceed 1 microg/m3 i.e. Polish permissible concentration for residence. However, in some of the hospital rooms, elevated concentrations of mercury vapor were found and airborne levels of up to 13.9 microg/m3 were recorded. Higher concentrations of mercury vapor were observed in autumn season when compared to summer. PMID:15931983

Prokopowicz, Adam; Mniszek, Wojciech

2005-05-01

239

Collisional stripping of Mercury's mantle  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

240

Flight to Mercury  

NASA Technical Reports Server (NTRS)

The project development and active flight of the Mariner 10 deep-space probe mission is recounted in detail, with sequential blow-by-blow coverage. Early studies and speculation on the planet Mercury are reviewed, and the spin-orbit coupling and near-synchronous rotation of the planet are described. Use of Venus as a slingshot in a gravity-assist maneuver is described, and Mariner 10 records of Venus are shown. The three encounters of Mariner 10 with Mercury (March 1974, Aug. 1974, March 1975) are described in detail, with purposes, problems, mishaps, and glossy photographs recovered from Mariner 10 data. Information on the planet's magnetosphere, surface topography, inferred internal structure, and IR signature is provided, and the end-of-mission improvised solar-sail experiment is outlined.

Murray, B.; Burgess, E.

1977-01-01

241

Mercury, Vaccines, and Autism  

PubMed Central

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

Baker, Jeffrey P.

2008-01-01

242

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

243

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

244

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

245

System for deposition and hydriding of thin metallic films without air exposure  

Microsoft Academic Search

A non-air exposed hydriding\\/deposition system provides advanced processing capability for hydriding erbium thin films. The system is designed with precise controls for cold crucible electron beam deposition of erbium, film deposition monitoring, and temperature bakeout. Using a mechanical transfer device, a complete hydriding process for erbium deposited films can be completed without air exposure. The system offers many processing improvements

C. C. Eichman; J. L. Comeau; K. R. Rinehuls

1974-01-01

246

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

247

Radar Imaging of Mercury  

Microsoft Academic Search

Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during\\u000a the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization\\u000a imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by

John K. Harmon

2007-01-01

248

Radar Imaging of Mercury  

Microsoft Academic Search

Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during\\u000a the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization\\u000a imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by

J. Harmon

2004-01-01

249

Radar Imaging of Mercury  

Microsoft Academic Search

Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by

John K. Harmon

2007-01-01

250

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

251

Mercury transport and resistance.  

PubMed

Resistance to mercuric ions in bacteria is conferred by mercuric reductase, which reduces Hg(II) to Hg(0) in the cytoplasmic compartment. Specific mercuric ion transport systems exist to take up Hg(II) salts and deliver them to the active site of the reductase. This short review discusses the role of transport proteins in resistance and the mechanism of transfer of Hg(II) between the mercury-resistance proteins. PMID:12196174

Brown, N L; Shih, Y-C; Leang, C; Glendinning, K J; Hobman, J L; Wilson, J R

2002-08-01

252

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

253

Interstellar sulfur hydride: a search for the 111-megahertz lines.  

PubMed

Similarities in the energy-level structure of the sulfur hydride radical and the hydroxyl radical suggest that sulfur hydride in the interstellar medium might be detectable because of a population inversion or anti-inversion similar to that of the hydroxyl radical. We have searched for the 111.54-megahertz transition [F (total angular momentum quantum number) = 2 --> 2] and for the 111.22-megahertz transition (F = 1 --> 1) in the galactic radio source W49, one of the brightest hydroxyl emission sources. No sulfur hydride emission lines with half-power widths of 130 hertz or greater were detected with the 1000-foot Arecibo antenna. The upper limits established with 100-hertz filters were 50 and 60 flux units (1 flux unit= 10(26) watt meter(-2) hertz(-1)), respectively, for the two lines. PMID:17738363

Meeks, M L; Gordon, M A; Litvak, M M

1969-01-10

254

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

255

Decomposition of the hexagonal copper hydride at high pressure  

NASA Astrophysics Data System (ADS)

The process of decomposition of hexagonal copper hydride has been observed in situ in a diamond anvil cell (DAC) using the energy dispersive X-ray diffraction (EDXRD) method. The presence and intensity of diffraction lines of the hexagonal CuH 0.8 phase have been taken as a probe for the decomposition process. The intensity of diffraction lines decreases abruptly in the vicinity of 8.4 GPa, indicating complete decomposition of the hydride. The determined value of decomposition pressure is equal to 8.4±0.6 GPa. The standard Gibbs energy of formation of 54.0±1.3 kJ mol -1 (H 2) calculated for copper hydride has been compared with the result obtained from calorimetric studies. The large discrepancy between the two values suggests that the decomposition pressure does not describe 'true' equilibrium conditions in this system.

Tkacz, M.; Burtovyy, R.

2004-10-01

256

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.

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

257

Hydrogen storage in fullerenes and in an organic hydride  

SciTech Connect

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

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

1998-05-29

258

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

259

Mercury exposure of maroon workers in the small scale gold mining in Suriname.  

PubMed

Suriname is experiencing a revival of small scale gold mining activities, with about 10,000 to 15,000 workers involved in 1996. The estimated production in 1995 is at least 10,000 kg crude gold. Gold is extracted with mercury and methods used are comparable with those described for gold mining in the Amazon Basin. Since no data exist on the internal mercury exposure of workers in Suriname a study was performed. A group of mercury-exposed Maroons, who are principally involved in the mining located in the tropical rainforest, is compared with nonexposed Maroons living in a non-gold mining area. Blood and urine samples of both groups were analyzed for total mercury using an atomic absorption spectrometer with an FIAS hydride system. In the study 28 exposed and 17 controls with a comparable mean age (P=0.544; exposed 27+/-7.2 years, n=26; controls 26+/-7.7 years, n=17), all males, participated. The urine levels for both groups differ statistically significantly from each other (P<0.001; exposed mean 27.5+/-21.1 microg/g creatinine; controls mean 5. 2+/-2.9 microg/g creatinine). This is, however, not the case with the blood levels (P=0.036: exposed mean 18.1+/-11.0 microg/L, n=25; controls mean 26.8+/-14.6 microg/L, n=16). In contrast with blood the urine total mercury levels in this study confirm, on a group basis, exposure to mercury as described for individuals working in the gold mining in the Amazon Basin. PMID:9600801

de Kom, J F; van der Voet, G B; de Wolff, F A

1998-05-01

260

Synthesis of mercury cuprates  

NASA Astrophysics Data System (ADS)

Mercury cuprates have very interesting potential applications that have not been thoroughly explored until now because of the complexity of their synthesis. This paper presents an overview of recent results concerning their processing. At first, a simple sol-gel technique is described that permits one to easily and intimately mix the precursors. The method uses the gelification of an inorganic solution of the cations by acrylamide polymerization. Mercuration of the precursor at moderate pressures (<2-5 MPa) is then discussed. The control of the total pressure during the synthesis by a simple method is shown, and this enables one to quantify some important parameters of the synthesis and to optimize the superconducting properties. This method has been also used successfully to incorporate mercury into layers of precursors and then to form thick layers of superconducting (Hg, Re)-1223, c-axis oriented. Finally, mercuration at higher pressures (up to 6 GPa) is considered and the case of the double mercury layer Hg-2212 is discussed in connection with the oxygen content of the reactants.

Odier, P.; Sin, A.; Toulemonde, P.; Bailly, A.; LeFloch, S.

2000-08-01

261

Uncratered Area on Mercury  

NASA Technical Reports Server (NTRS)

A dark, smooth, relatively uncratered area on Mercury was photographed (FDS 226) two hours after Mariner 10 flew by the planet on March 29 from a range of 86,000 kilometers (54,000 miles). Above and to the left of center is a surface similar to the mane material of Earth's moon. It embays and covers rougher, older, heavily cratered topography like that, which can be seen in both upper corners of this picture. The history of heavy cratering seems to be followed by volcanic filling, similar to the process on the Moon. The prominent, sharp crater with a central peak (center) is 30 kilometers (19 miles) across. It is located on the upper left edge of a very bright surface area. The bright crater, to its right is 10 kilometers (6 miles) in diameter. The sun is from the right.

The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA/JPL/Northwestern University

1974-01-01

262

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

263

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

264

Ab-initio study of transition metal hydrides  

NASA Astrophysics Data System (ADS)

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

2014-04-01

265

Materials science of Mg-Ni-based new hydrides  

Microsoft Academic Search

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

S. Orimo; H. Fujii

2001-01-01

266

Electrochemical hydride generation for the simultaneous determination of hydride forming elements by inductively coupled plasma-atomic emission spectrometry  

NASA Astrophysics Data System (ADS)

Simultaneous measurements of As, Sb, Se, Sn and Ge were performed by inductively coupled plasma atomic emission spectrometry following their electrochemical hydride generation. An electrochemical hydride generator based on a concentric arrangement with a porous cathode, working in a continuous flow mode was used. The effects of sample flow rate, applied current and electrolytic solution concentration on response were studied and their influence on the mechanisms of hydride generation discussed. Four materials, particulate lead, reticulated vitreous carbon (RVC), silver and amalgamated silver were tested as cathode materials. The best results were achieved with particulate lead and RVC cathodes, wherein generation efficiencies higher than 80% were estimated for most of the analytes. In general, limits of detection between 0.1 and 3.6 ng ml -1 and a precision better than 5% were achieved using a lead cathode. The analysis of a marine sediment reference material (PACS-2, NRC) showed good agreement with the certified values for As and Se.

Bolea, E.; Laborda, F.; Castillo, J. R.; Sturgeon, R. E.

2004-04-01

267

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

268

Paraboloid model of Mercury's magnetosphere  

Microsoft Academic Search

A new “Paraboloidal” model of Mercury's magnetospheric magnetic field based upon the earlier terrestrial model and using similar techniques is developed. The model describes the field of Mercury's dipole, which is considered to be offset from the planet's center; the magnetopause currents driven by the solar wind; and the tail current system including the cross-tail currents and their closure currents

I. I. Alexeev; E. S. Belenkaya; S. Yu. Bobrovnikov; J. A. Slavin; M. Sarantos

2008-01-01

269

Mercury wetting film on sapphire  

Microsoft Academic Search

We have measured optical properties of a mercury wetting film on sapphire under high temperature and high pressure near the liquid-gas critical point of mercury by using a newly developed 45° reflection technique. We have analyzed the experimental data to deduce the density, the thickness, and the coverage of the wetting film quantitatively as functions of pressure and temperature. As

Y. Ohmasa; Y. Kajihara; M. Yao

2001-01-01

270

Formation of Mercury's smooth plains  

Microsoft Academic Search

Indirect evidence is presented for a volcanic origin in the case of two smooth plains on Mercury, the Borealis Planitia and the Hilly and Lineated Terrain. These results, in conjunction with those previously obtained for the circum-Caloris plains and the Tolstoj basin, indicate that smooth plains volcanism was a global process on Mercury. It is further suggested that the smooth

W. S. Kiefer; B. C. Murray

1987-01-01

271

Mercury Contamination in Costa Rica  

Microsoft Academic Search

Mercury is a potent neurotoxin and a particularly formidable environmental contaminant. Mercury is present in the environment largely as a result of modern industrial emissions as well as ‘legacy-Hg’ from past contamination; however, some areas have high natural background levels also, largely from volcanic and geothermal sources. Recent work suggested that Costa Rica airshed may be highly contaminated with natural

Audrey Fitzgerald Haynes

2012-01-01

272

Paraboloid model of Mercury's magnetosphere  

Microsoft Academic Search

A new ``Paraboloidal'' model of Mercury's magnetospheric magnetic field based upon the earlier terrestrial model and using similar techniques is developed. The model describes the field of Mercury's dipole, which is considered to be offset from the planet's center; the magnetopause currents driven by the solar wind; and the tail current system including the cross-tail currents and their closure currents

I. I. Alexeev; E. S. Belenkaya; S. Yu. Bobrovnikov; J. A. Slavin; M. Sarantos

2008-01-01

273

Mercury and autism: Accelerating Evidence?  

Microsoft Academic Search

The causes of autism and neurodevelopmental disorders are unknown. Genetic and environmental risk factors seem to be involved. Because of an observed increase in autism in the last decades, which parallels cumulative mercury expo- sure, it was proposed that autism may be in part caused by mercury. We review the evidence for this proposal. Several epidemiological studies failed to find

Joachim Mutter; Johannes Naumann; Rainer Schneider; Harald Walach; Boyd Haley

2005-01-01

274

Near Global Mosaic of Mercury  

Microsoft Academic Search

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

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

2009-01-01

275

Planetary science: Shrinking wrinkling Mercury  

NASA Astrophysics Data System (ADS)

As Mercury's interior cools and its massive iron core freezes, its surface feels the squeeze. A comprehensive global census of compressional deformation features indicates that Mercury has shrunk by at least 5 km in radius over the past 4 billion years.

McKinnon, William B.

2014-04-01

276

Mercury Removal from Waste Organics  

SciTech Connect

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

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

1999-02-28

277

Compression equations for mercury porosimetry  

NASA Astrophysics Data System (ADS)

Methods for obtaining isothermal pressure-volume data using a mercury porosimeter and for completely correcting this data for compression effects are described. The isothermal compressions of several liquids were measured with a 103 MPa (15,000 psi) mercury porosimeter using the principles described. The porosites and surface areas of several areas of several macroporous solids were accurately measured.

Smithwick, R. W., III

1982-05-01

278

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

279

Mercury: Beethoven Quadrangle, H-7  

NASA Technical Reports Server (NTRS)

Mercury: Computer Photomosaic of the Beethoven Quadrangle, H-7 The Beethoven Quadrangle, named for the 19th century classical German composer, lies in Mercury's Equatorial Mercator located between longitude 740 to 1440. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet. The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The images used to construct the Beethoven Quadrangle were taken as Mariner 10 flew passed Mercury. The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission. The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

2000-01-01

280

Hydride vapor phase epitaxy of aluminum nitride  

NASA Astrophysics Data System (ADS)

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

Kamber, Derrick Shane

281

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

SciTech Connect

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

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

2001-03-01

282

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.

283

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

284

Dental amalgam mercury exposure in rats  

Microsoft Academic Search

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

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

1999-01-01

285

In situ stabilization of entrapped elemental mercury.  

PubMed

Elemental mercury is a dense immiscible fluid which gets entrapped as residual mercury in the pore spaces of the subsurface during improper disposals and accidental spills. This paper investigates in situ stabilization of entrapped elemental mercury to mercury sulphide using aqueous sodium polysulphide solution. Batch experiments showed 100% conversion efficiency of elemental mercury to mercury sulphide in a period of 96 h with sodium polysulphide/elemental mercury molar ratio of 1. XRD analysis identified the precipitate formed as mercury sulphide. Micromodel experiments, with glass beads as porous media, further demonstrated in situ stabilization of entrapped mercury under different residual mercury saturations. It was found that in a period of 10 days, 10% of entrapped mercury was stabilized as mercury sulphide, 0.088% was removed as dissolved mercury and the remaining elemental mercury was retained in porous media encapsulated by the newly formed mercury sulphide precipitate. However, there was no leaching of mercury from the micromodel effluent once stabilization was achieved. PMID:24080327

Devasena, M; Nambi, Indumathi M

2013-11-30

286

Fabrication of lotus-type porous copper through thermal decomposition of titanium hydride  

NASA Astrophysics Data System (ADS)

Lotus-type porous copper was fabricated by unidirectional solidification through thermal decomposition of titanium hydride. Effects of additive method and additive amount of titanium hydride on pore formation were investigated. The porosity of lotus copper depends on additive method and additive amount of titanium hydride. The pore formation effectively occurs in the method that titanium hydride decomposes in molten copper. For all the additive methods of titanium hydride, the porosity increases and pore diameter does not change with increasing additive amount of titanium hydride. While, for adding large amount of titanium hydride, the porosity became constant. This is because hydrogen solubility in liquid phase does not change owing to bubbling of hydrogen gas.

Ide, T.; Nakajima, H.

2009-05-01

287

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

288

Safety Evaluation of Magnesium Hydride in Energy Storage.  

National Technical Information Service (NTIS)

Investigations of the magnesium/magnesium hydride system and its potential in energy storage have been carried out at Risoe National Laboratory for some years. The results of this research indicate that the system is technically feasible, at least in some...

B. Vigeholm

1986-01-01

289

Aluminium hydride: a reversible material for hydrogen storage.  

PubMed

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

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

2009-07-01

290

Investigation of Galvanically Induced Hydriding of Titanium in Saline Solutions.  

National Technical Information Service (NTIS)

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

L. A. Charlot

1970-01-01

291

Hydride generation from the Exide load-leveling cells  

NASA Astrophysics Data System (ADS)

Stibine and arsine evolution from lead-acid cells in a 36-kWh Exide load-leveling module was measured as this module approached 1900 cycles of operation. A gas-collection apparatus enabled us to determine the maximum and average rates for evolution of both toxic hydrides. Hydride generation began once the cell voltage exceeded 2.4 V. The maximum rate for arsine occurred just above 2.5 V and consistently preceded the peak rate for stibine for each sampled cell. The average rates of hydride generation were found to be 175 g/min for stibine and 12.6 g/min for arsine. The former rate proved to be the critical value in determining safe ventilation requirements for cell off-gases. The minimum airflow requirement was calculated to be 340 L/min per cell. Projections for a hypothetical 1-MWh Exide battery without an abatement system indicated that the normal ventilation capacity in the Battery Energy Storage Test facility provides nearly five times the airflow needed for safe hydride removal.

Marr, J. J.; Smaga, J. A.

1987-05-01

292

Rhodium Carbonyl Hydride Species. A Theoretical and Experimental Investigation.  

National Technical Information Service (NTIS)

A theoretical investigation (ab initio) and experimental data have been combined in an attempt to characterize the rhodium carbonyl hydride species which has been shown previously in these laboratories and in those of Solymosi to be a long-lived surface s...

M. L. McKee C. H. Dai S. D. Worley

1987-01-01

293

Subcritical crack growth behavior for hydrided Zircaloy4 plate  

Microsoft Academic Search

To study the subcritical crack growth (SCG) behavior for hydrided Zircaloy-4 plate, sustained load tests were performed on fatigue precracked specimens in Ar atmosphere at 200, 250, and 300 °C with hydrogen contents up to 290 ppm. Log crack velocity versus stress intensity curves showed typical three-stage crack growth behavior. The values of threshold stress intensity (Kth) were not sensitive

J.-H. Huang; C.-S. Ho

1997-01-01

294

Stable silver(I) hydride complexes supported by diselenophosphate ligands.  

PubMed

The first stable structure of silver(I) cluster cations [Ag(8)(mu(4)-H){Se(2)P(OR)(2)}(6)](+) [R = (i)Pr, 1; Et, 2] containing Ag(I)-hydride bridges (Ag-mu-H-Ag) in T symmetry was reported. The clusters having an interstitial hydride were composed of an octanuclear silver core in tetracapped tetrahedral geometry, which was inscribed within a Se(12) icosahedron represented by six dialkyl diselenophosphate ligands in a tetrametallic-tetraconnective (mu(2), mu(2)) bonding mode. The presence of hydride was unequivocally corroborated by both (1)H and (109)Ag NMR spectroscopies of which a nonet in the (1)H NMR spectrum for the hydride resonance coupled with a doublet peak observed in the (109)Ag NMR spectrum clearly suggests that eight silver nuclei are equivalent in the NMR time scale and a fast exchange of the positions between the vertex and capping silver atoms in solution must occur. The hypothesis was also supported by a density functional theory (DFT) investigation on a simplified model [Ag(8)(H)(Se(2)PH(2))(6)](+), which confirmed that the Ag(8)H cubic core of T(h) symmetry may not be formed as it is energetically highly unfavorable (0.67 eV less stable than the T structure). PMID:20025253

Liu, C W; Chang, Hao-Wei; Sarkar, Bijay; Saillard, Jean-Yves; Kahlal, Samia; Wu, Ying-Yann

2010-01-18

295

Electron and Nuclear Magnetic Resonances in Compounds and Metallic Hydrides.  

National Technical Information Service (NTIS)

Proton pulsed Nuclear Magnetic Resonance measurements were performed on the metallic hydrides ZrCr2 H/sub x/ (x = 2, 3, 4) and ZrV2 H/sub y/ (y = 2, 3, 4, 5) as a function of temperature between 180 and 400K. The ultimate aim was the investigation of the ...

N. Brasil Filho

1985-01-01

296

Process of forming a sol-gel/metal hydride composite  

DOEpatents

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

Congdon, James W. (Aiken, SC)

2009-03-17

297

Fluorescent sensor for mercury  

DOEpatents

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

298

The Origin of Mercury  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

299

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

300

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...

301

Hydriding of titanium. Annual report number 2 for 1997  

SciTech Connect

The reason for undertaking this work is that the US Navy would like to use titanium in a number of critical applications, where it would come in contact with sea water at elevated temperatures. Although the general reputation of titanium is that it is corrosion resistant in these environments, there is the possibility that it could pick up sufficient hydrogen from this environment to form a hydride and thus lose its mechanical integrity. Therefore, one must evaluate all conditions that could lead to hydriding and determine the effects of hydrides on mechanical properties. During the second year of work, the goals have been the following: to determine the effect of solution activity and temperature, material composition and heat treatment on the electrochemical properties of titanium; to determine the effect of these same variables on the corrosion potential of titanium galvanically coupled with other metals; to determine the critical potential of hydride formation as a function of solution activity and temperature, applied strain, and surface conditions; to measure the rate of hydrogen diffusion in titanium; to propose a model to describe crack propagation in titanium in these environments. All of the above work has been completed and the results are contained in this document. The results that the authors have obtained show that grade 2 titanium is generally resistant to hydrogen embrittlement. However, grade 3, with its higher interstitial content and lower hydrogen solubility is quite susceptible to hydrogen embrittlement. The mechanism by which this embrittlement occurs is one in which microcracks, which are centered on hydrides, form ahead of the main crack tip. With increased deformation these microcracks link up to the main crack and cause propagation.

Briant, C.L.; Kumar, K.S.; Wang, Z.

1998-03-01

302

5-year review of Metal Hydride Center of Excellence.  

SciTech Connect

The purpose of the DOE Metal Hydride Center of Excellence (MHCoE) is to develop hydrogen storage materials with engineering properties that allow the use of these materials in a way that satisfies the DOE/FreedomCAR Program system requirements for automotive hydrogen storage. The Center is a multidisciplinary and collaborative effort with technical interactions divided into two broad areas: (1) mechanisms and modeling (which provide a theoretically driven basis for pursuing new materials) and (2) materials development (in which new materials are synthesized and characterized). Driving all of this work are the hydrogen storage system specifications outlined by the FreedomCAR Program for 2010 and 2015. The organization of the MHCoE during the past year is show in Figure 1. During the past year, the technical work was divided into four project areas. The purpose of the project areas is to organize the MHCoE technical work along appropriate and flexible technical lines. The four areas summarized are: (1) Project A - Destabilized Hydrides, The objective of this project is to controllably modify the thermodynamics of hydrogen sorption reactions in light metal hydrides using hydride destabilization strategies; (2) Project B - Complex Anionic Materials, The objective is to predict and synthesize highly promising new anionic hydride materials; (3) Project C - Amides/Imides Storage Materials, The objective of Project C is to assess the viability of amides and imides (inorganic materials containing NH{sub 2} and NH moieties, respectively) for onboard hydrogen storage; and (4) Project D - Alane, AlH{sub 3}, The objective of Project D is to understand the sorption and regeneration properties of AlH{sub 3} for hydrogen storage.

Keller, Jay O.; Klebanoff, Leonard E.

2010-05-01

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 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

305

Modeling the obliquity of Mercury  

NASA Astrophysics Data System (ADS)

Mercury is the target of the space missions MESSENGER and BepiColombo, that will in particular observe its rotation to get information on its internal structure. This requires a rigorous modelization of this rotation. A difficulty comes from the obliquity of Mercury, that behaves adiabatically, and so is tough to simulate over a short timescale without generating free oscillations. These free oscillations are due to the inaccuracy of the initial conditions, that are difficult to determine because they correspond to an equilibrium of the complete, perturbed problem. We here propose formulae linking the long-term behavior of the obliquity of Mercury with its gravity parameters C20, C22 and C/(MR2), based on Peale's (1981) formula. We use for that a fitted precessional motion of Mercury that we include in averaged rotational equations, and we show that the solutions extracted can be used in a realistic simulation suitable to a space mission. We estimate that these solutions induce an error lower than 3% in the modelization of Mercury's obliquity. Thus, an inversion of the observed orientation of Mercury could lead to an uncertainty of 3% on Mercury's inertial polar momentum, if we neglect the other sources of error.

Noyelles, Benoît; D'Hoedt, Sandrine

2012-01-01

306

Investigations of the feasibility of constructing a polypyrrole-mercury\\/mercury chloride reference electrode  

Microsoft Academic Search

A polypyrrole-mercury\\/mercury chloride reference electrode was initially constructed by in situ electropolymerization of pyrrole on a mercury pool anode in a 0.5 M sodium para-toluene sulfonate and 1.0 M sodium chloride mixture solution. However, in this procedure, insufficient amount of mercury was incorporated in the polypyrrole film for reaction with chloride ions to yield a mercury\\/mercury chloride half cell. Alternatively,

Nicole L. Pickup; Meng Lam; Dusan Milojevic; Richard Y. Bi; Jacob S. Shapiro; Danny K. Y. Wong

1997-01-01

307

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

Microsoft Academic Search

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

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

1978-01-01

308

MESSENGER'S First Flyby of Mercury  

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. 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. An overview of the MESSENGER mission and its January 14th close flyby of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER'S first flyby on January 14th, 2008 will be discussed with an emphasis on the magnetic field and charged particle measurements.

Slavin, James A.

2008-01-01

309

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

1998-01-01

310

Seasonal variations in Mercury’s dayside calcium exosphere  

NASA Astrophysics Data System (ADS)

The Mercury Atmospheric and Surface Composition Spectrometer on the MESSENGER spacecraft has observed calcium emission in Mercury’s exosphere on a near-daily basis since March 2011. During MESSENGER’s primary and first extended missions (March 2011 - March 2013) the dayside calcium exosphere was measured over eight Mercury years. We have simulated these data with a Monte Carlo model of exospheric source processes to show that (a) there is a persistent source of energetic calcium located in the dawn equatorial region, (b) there is a seasonal dependence in the calcium source rate, and (c) there are no obvious year-to-year variations in the near-surface dayside calcium exosphere.

Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Merkel, Aimee W.; Vervack, Ronald J.; Cassidy, Timothy A.; Sarantos, Menelaos

2014-08-01

311

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

312

Exploring metal hydrides using autoclave and multi-anvil hydrogenations  

NASA Astrophysics Data System (ADS)

Metal hydride materials have been intensively studied for hydrogen storage applications. In addition to potential hydrogen economy applications, metal hydrides offer a wide variety of other interesting properties. For example, hydrogen-dominant materials, which are hydrides with the highest hydrogen content for a particular metal/semimetal composition, are predicted to display high-temperature superconductivity. On the other side of the spectrum are hydrides with small amounts of hydrogen (0.1 - 1 at.%) that are investigated as viable magnetic, thermoelectric or semiconducting materials. Research of metal hydride materials is generally important to gain fundamental understanding of metal-hydrogen interactions in materials. Hydrogenation of Zintl phases, which are defined as compounds between an active metal (alkali, alkaline earth, rare earth) and a p-block metal/semimetal, were attempted by a hot sintering method utilizing an autoclave loaded with gaseous hydrogen (< 9 MPa). Hydride formation competes with oxidative decomposition of a Zintl phase. The oxidative decomposition, which leads to a mixture of binary active metal hydride and p-block element, was observed for investigated aluminum (Al) and gallium (Ga) containing Zintl phases. However, a new phase Li2Al was discovered when Zintl phase precursors were synthesized. Using the single crystal x-ray diffraction (SCXRD), the Li2Al was found to crystallize in an orthorhombic unit cell (Cmcm) with the lattice parameters a = 4.6404(8) Å, b = 9.719(2) Å, and c = 4.4764(8) Å. Increased demand for materials with improved properties necessitates the exploration of alternative synthesis methods. Conventional metal hydride synthesis methods, like ball-milling and autoclave technique, are not responding to the demands of finding new materials. A viable alternative synthesis method is the application of high pressure for the preparation of hydrogen-dominant materials. Extreme pressures in the gigapascal ranges can open access to new metal hydrides with novel structures and properties, because of the drastically increased chemical potential of hydrogen. Pressures up to 10 GPa can be easily achieved using the multi-anvil (MA) hydrogenations while maintaining sufficient sample volume for structure and property characterization. Gigapascal MA hydrogenations using ammonia borane (BH3

Puhakainen, Kati

313

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 ...

314

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

Federal Register 2010, 2011, 2012, 2013

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

2011-12-02

315

Mercury Telluride and Cadmium Telluride  

NASA Technical Reports Server (NTRS)

A semiconductor's usefulness is determined by how atoms are ordered within the crystal's underlying three-dimensional structure. While this mercury telluride and cadmium telluride alloy sample mixes completely in Earth -based laboratories, convective flows prevent them from mixing uniformly.

2004-01-01

316

CAPSULE REPORT: AQUEOUS MERCURY TREATMENT  

EPA Science Inventory

This report describes established technologies and identifies evolving methods for treating aqueous mercury. The information provided encompasses full-, pilot- and bench-scale treatment results as presented in the technical literature. The report describes alternative technologi...

317

Unlocking the Secrets of Mercury  

NASA Video Gallery

Of all the rocky planets, Mercury is the smallest and densest, the one with the oldest surface, and the one with the largest daily surface temperature variations. It is also the least explored! Joi...

318

Analysis of mercury diffusion pumps.  

National Technical Information Service (NTIS)

Several mercury diffusion pump stages in the Tritium Purification process at the Savannah River Site (SRS) have been removed from service for scheduled preventive maintenance. These stages have been examined to determine if failure has occurred. Evidence ...

K. A. Dunn

1991-01-01

319

The Mercury Dual Orbiter mission  

NASA Technical Reports Server (NTRS)

The Mercury Orbiter (MeO) will carry out a full range of particles, fields, and planetary imaging science at Mercury. Present mission plans call for a launch in 1999 with a flight time of about 4.5 years. By means of multiple Venus and Mercury gravitational assists, the mission can be accomplished with present U.S. launch vehicles and a very large payload can be placed in orbit around Mercury. The dual-spacecraft concept will permit outstanding scientific study of solar cosmic rays and the solar wind throughout the inner heliosphere from 0.3 AU to 1.0 AU. Modest enhancements to the planned magnetospheric instruments and utilization of onboard solar instruments will permit unique investigation of solar particle acceleration and transport with the MeO spacecraft.

Baker, D. N.; Slavin, J. A.

1990-01-01

320

The Mercury dual orbiter mission  

NASA Astrophysics Data System (ADS)

The Mercury Orbiter (MeO) will carry out a full range of particles, fields, and planetary imaging science at Mercury. Present mission plans call for a launch in 1999 with a flight time of about 4.5 years. By means of multiple Venus and Mercury gravitational assists, the mission can be accomplished with present U.S. launch vehicles and a very large payload can be placed in orbit around Mercury. The dual-spacecraft concept will permit outstanding scientific study of solar cosmic rays and the solar wind throughout the inner heliosphere from 0.3 AU to 1.0 AU. Modest enhancements to the planned magnetospheric instruments and utilization of onboard solar instruments will permit unique investigation of solar particle acceleration and transport with the MeO spacecraft.

Baker, D. N.; Slavin, J. A.

1990-03-01

321

Mercury orbiter transport study  

NASA Technical Reports Server (NTRS)

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

Friedlander, A. L.; Feingold, H.

1977-01-01

322

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

323

Mercury Toolset for Spatiotemporal Metadata  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

324

In situ mercury stabilization  

SciTech Connect

BNL Royalty Project Internal Status Report. The funds from the allotment of royalty income were used to experimentally explore feasibility of related, potential new techniques based on the Environmental Sciences Department successful technology licensed for the ex situ treatment of mercury. Specifically, this work is exploring the concept of using Sulfur Polymer Cement (SPC) in an in situ application to stabilize and/or remove mercury (Hg) from surficial soil. Patent disclosure forms have been filed for this process. Soil was artificially spiked with 500 ppm Hg and a series of experiments were set up in which SPC rods were placed in the center of a mass of this soil. Some experiments were conducted at 20 C and others at 50 C. After times ranging from 11 to 24 days, these experiments were opened, photographed and the soil was sampled from discrete locations in the containers. The soil and SPC samples were analyzed for Fe and Hg by x-ray fluorescence. The Hg profile in the soil was significantly altered, with concentrations along the outer edge of the soil reduced by as much as 80% from the starting concentration. Conversely, closer to the treatment rod containing SPC, concentrations of Hg were significantly increased over the original concentration. Preliminary results for elevated temperature sample are shown graphically in Figure 2. Apparently the Hg had migrated toward the SPC and reacted with sulfur to form Hg S. This appears to be a reaction between gaseous phases of both S and Hg, with Hg having a greater vapor pressure. The concentration of low solubility HgS (i.e., low leaching properties) developed within 11 days at 50 C and 21 days at 20 C, confirming the potential of this concept.

Fuhrmann, M.; Kalb, P.; Adams, J.

2004-09-01

325

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

326

Transformation of Elemental Mercury by Bacteria  

PubMed Central

The fate and impact of elemental mercury in closed bacterial cultures were examined. The quantity of elemental mercury oxidized by bacteria ranged from small amounts for Pseudomonas aeruginosa, P. fluorescens, Escherichia coli, and Citrobacter to essentially all of the added elemental mercury for Bacillus subtilis and B. megaterium. The percentage of the total mercury in the system associated with bacterial cells ranged from 18.6 43.2%. Growth of the two Pseudomonas species was inhibited by elemental mercury, whereas growth of the other cultures was not distinguishable from that in mercury-free controls. No methylmercury was formed by the six cultures within 48 h.

Holm, Harvey W.; Cox, Marilyn F.

1975-01-01

327

Mercury in Wetlands, Adirondack Region of New York State  

Microsoft Academic Search

Wetlands play a prominent role in the cycling of mercury by harboring bacteria that transform mercury into methyl mercury, a neurotoxin, and by having high concentrations of dissolved organic carbon (DOC) that interact with mercury transport. We are measuring total mercury and methyl mercury in vegetation, soil, surface water, and ground water in the Sunday Lake watershed, in which wetlands

J. B. Yavitt; M. Kalicin; C. T. Driscoll; R. Newton; R. Munson

2001-01-01

328

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

329

Regeneration of Aluminum Hydride studied with Raman Microscopy.  

NASA Astrophysics Data System (ADS)

We are interested in developing new methods to form aluminum hydride directly from aluminum powder and hydrogen. Due to the low free energy of formation, aluminum and hydrogen require extremely high pressures to react and form the hydride. It is possible to form alane directly at low pressure when it is catalyzed with a small amount of titanium (2 mol %) and stabilized as an adduct. We have studied the formation of amine-alanes by direct hydrogenation of aluminum and have attempted to understand the mechanisms behind these reversible reactions and the role of the catalyst. We will present the results from our recent survey of possible reactions between aluminum, hydrogen and various amines. We will also present the results of a Raman spectroscopy study of the alane polymorphs at ambient and high pressure and alane amines.

Lacina, David; Graetz, Jason; Reilly, J. J.

2009-03-01

330

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

331

Low temperature study of structural phase transitions in niobium hydrides  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

332

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 ...

333

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...

334

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

335

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

336

Hydriding kinetics of an organic hydrogen getter-DPB  

Microsoft Academic Search

The hydriding rate of DPB (diphenyl butadiyne\\/25% C (1% Pd)) organic hydrogen getter has been measured at 17°C over the range of 10?6 to 10?11molH (gDPB)?1s?1, H2 pressure 100–0.1Pa, reaction extent 0–29mmolH (gDPB)?1 and described by an algebraic model.

G. L. Powell

2007-01-01

337

Optical properties of metal-hydride switchable films  

Microsoft Academic Search

In 1996 we discovered that yttrium-, lanthanum-, and rare-earth-hydride (REHx) films [1] protected by a thin palladium layer, exhibit spectacular changes in their optical properties when the hydrogen concentration x is increased from 2 to 3. For example, a 500 nm thick YH2 film is metallic and shiny while YH3 is yellowish and transparent. The transition is reversible, fast [2,

Ronald Griessen

2001-01-01

338

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

339

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

PubMed Central

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

Felderhoff, Michael; Bogdanovic, Borislav

2009-01-01

340

Complications from Dual Roles of Sodium Hydride as a Base and as a Reducing Agent  

PubMed Central

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.

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

2012-01-01

341

Non-toxic hydride energy source for biochemical and industrial venues: ORP and NAD + reduction analyses  

Microsoft Academic Search

A recently described novel compound, silica hydride, was used to investigate potential alternative hydrogen energy sources for use in industry, pharmacology and biochemistry. Acting as an anionic hydride, the silica hydride does not react violently with water and produces stable oxidation-reduction potential readings of greater than ?860mV for extended periods providing capacity as an alternative for current transfer, hydrogen production

Cory J. Stephanson; G. Patrick Flanagan

2004-01-01

342

On the role of the indenyl effect in controlling intramolecular hydride transfer in iron carbonyl complexes  

Microsoft Academic Search

Density functional theory reveals multiple pathways for intramolecular hydride transfer in the cyclopentadienyl and indenyl species (?5-C5H5)Fe(CO)3H and (?5-C9H7)Fe(CO)3H. The ability of the indenyl ligand to undergo facile ?5- to ?3-‘ring slippage’ stabilises the isomer where the hydride is bonded directly to the metal, which opens up a low-energy pathway for hydride transfer from CO to metal.

Hakim Ahmed; John E. McGrady

2008-01-01

343

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

344

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

345

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

346

Metal hydride/chemical heat pump development project  

NASA Astrophysics Data System (ADS)

A mental hydride heat pump (MHHP) is a chemical heat pump containing two different hydrides and using hydrogen as a working fluid for the storage and/or recovery of thermal energy. It utilizes the heat of reaction of hydrogen with specific metal alloys. The MHHP design can be tailored to provide heating and cooling or temperature upgrading over a wide range of input and ambient temperatures. This system can be used with a variety of heat sources including industrial waste heat, solar energy or a fossil fuel. Temperature as low as 130 F can drive the MHHP when a suitable sink is provided. A project is currently underway to develop this unique heat pump for a specific application. The goals of the project include the development of cost effective hydride containers with high heat transfer and low mass; design and fabrication of a laboratory evaluation model; and design and fabrication of a demonstration unit. Extensive component and system test will provide the data for the design processes.

Madariaga, H. A.; Rohy, D. A.

1982-02-01

347

Delayed hydride cracking of spent fuel rods in dry storage  

NASA Astrophysics Data System (ADS)

Failures of zirconium alloy cladding tubes during a long-term storage at room temperature were first reported by Simpson and Ells in 1974, which remains unresolved by the old delayed hydride cracking (DHC) models. Using our new DHC model, we examined failures of cladding tubes after their storage at room temperature. Stress-induced hydride phase transformation from ? to ? at a crack tip creates a difference in hydrogen concentration between the bulk region and the crack tip due to a higher hydrogen solubility of the ?-hydride, which is a driving force for DHC at low temperatures. Accounting for our new DHC model and the failures of zirconium alloy cladding tubes during long-term storage at room temperature, we suggest that the spent fuel rods to be stored either in an isothermal condition or in a slow cooling condition would fail by DHC during their dry storage upon cooling to below 180 °C. Further works are recommended to establish DHC failure criterion for the spent fuel rods that are being stored in dry storage.

Kim, Young Suk

2008-08-01

348

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

349

Structural Stabilities and Electronic Properties of Cobalt Hydrides  

NASA Astrophysics Data System (ADS)

Cobalt forms ferromagnetic hydrides CoHx at high pressures of hydrogen [1]. As the hydrogen pressure increases at temperatures 250-350^oC, the concentration of hydrogen in the hcp phase monotonically increases, and reaches x˜0.6 at 7 GPa. At higher pressures, an fcc-based hydride with x˜1.0 is formed. At ambient pressure and 120 K, hydrogen atoms in the solution with x<=0.26 are randomly distributed over octahedral interstitial sites [2]. In the solution with x=0.34 (x>=0.38), hydrogen atoms occupy every third (second) layer. The magnetic moments of the hcp-based hydrides are oriented to the c-axis, and are decreased with increasing hydrogen concentration at a rate of about 0.36 ?B per hydrogen atom. In this study, we optimize the structural parameters for several structures, and investigate the structural stabilities and related electronic properties by using first-principles calculations. The full-potential linearized augmented plane wave method with the generalized gradient approximation is adopted.[4pt] [1] V. E. Antonov, J. Alloys Compd. 330-332, 110 (2002).[0pt] [2] V. K. Fedotov, V. E. Antonov, T. E. Antonova, E. L. Bokhenkov, B. Dorner, G. Grosse, and F. E. Wagner, J. Alloys Compd. 291, 1 (1999).

Matsuura, Yasuyuki; Shishidou, Tatsuya; Oguchi, Tamio

2011-03-01

350

Experimental studies on the behaviours of hydride heat storage system  

NASA Astrophysics Data System (ADS)

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

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

351

Moessbauer investigation of intermetallic hydrides. Final report, 1 November 1982-31 October 1985  

SciTech Connect

This research was a study of hydrogen absorption in intermetallic hydrides. Mossbauer and x-ray-diffraction measurements were used to aid in a determination of the hydrogen-absorbing mechanism occurring in hydriding. Information was sought that would provide insight into the nature of bonding and interaction between the absorbed hydrogen and the various sites in the intermetallics. There was also interest in observing what happened to Sn in intermetallic compounds when hydrided. Studies were made of the changes in isomer shift and linewidth upon hydriding.

Oliver, F.W.

1985-12-21

352

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

353

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...

354

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

355

Nucleotide sequence of a chromosomal mercury resistance determinant from a Bacillus sp. with broad-spectrum mercury resistance. [Mercury reductase  

Microsoft Academic Search

A 13.5-kilobase HindIII fragment, bearing an intact mercury resistance (mer) operon, was isolated from chromosomal DNA of broad-spectrum mercury-resistant Bacillus sp. strain RC607 by using as a probe a clone containing the mercury reductase (merA) gene. The new clone, pYW33, expressed broad-spectrum mercury resistance both in Escherichia coli and in Bacillus subtilis, but only in B. subtilis was the mercuric

Y. Wang; H. S. Levinson; I. Mahler; M. Moore; C. Walsh; S. Silver

1989-01-01

356

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.

357

Mercury Emission Measurement at a CFB Plant.  

National Technical Information Service (NTIS)

In response to pending regulation to control mercury emissions in the United States and Canada, several projects have been conducted to perform accurate mass balances at pulverized coal (pc)-fired utilities. Part of the mercury mass balance always include...

J. Pavlish J. Thompson L. Hamre

2009-01-01

358

The chemistry of atmospheric mercury: a review  

NASA Astrophysics Data System (ADS)

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 article provides selected physical and chemical properties of atmospheric mercury, and discusses the identified mercury transformation pathways mediated by ozone, S(IV), hydroperoxyl radical, hydroxyl radical, chlorine, nitrate radical and photolysis of Hg(II) complexes. Special attention is paid to the kinetics and mechanisms of the reactions interconverting mercury between elemental and divalent states. The significance and implications of each transformation pathway under atmospheric conditions are addressed. Future research areas that must be pursued to better understand the fate and transformation of mercury in the atmosphere are also projected.

Lin, Che-Jen; Pehkonen, Simo O.

359

The evaporation of a drop of mercury  

NASA Astrophysics Data System (ADS)

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

Winter, Thomas G.

2003-08-01

360

Mercury Compounds in Drugs and Food.  

National Technical Information Service (NTIS)

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

1999-01-01

361

2006 mercury control technology conference. Proceedings  

SciTech Connect

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

NONE

2006-07-01

362

Control of Mercury Contamination in Freshwater Sediments.  

National Technical Information Service (NTIS)

Methods for controlling the release of mercury from sediments have been developed, and the effects of dredging on the redistribution of mercury have been evaluated. Laboratory studies consisted of both partitioning and aquarium experiments using artificia...

G. Feick E. E. Johanson D. S. Yeaple

1972-01-01

363

MERCURY RESEARCH STRATEGY (WORKSHOP REVIEW DRAFT)  

EPA Science Inventory

The Mercury Research Strategy describes a research program that provides information, methods, models, and data to address key scientific questions of greatest concern to EPA, reducing uncertainties currently limiting the Agency's ability to assess and manage mercury and methylme...

364

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

365

Dual-mode chemical vapor generation for simultaneous determination of hydride-forming and non-hydride-forming elements by atomic fluorescence spectrometry.  

PubMed

A dual-mode chemical vapor generation integrating hydride generation and photochemical vapor generation was developed for simultaneous multi-element analysis of hydride-forming and non-hydride-forming elements by atomic fluorescence spectrometry. Four elements were selected as model elements of hydride-forming (As, Cd) and non-hydride-forming (Ni, Fe) elements to validate this proposed method. Standard or sample solutions were separately pumped to mix with tetrahydroborate, and concentrated formic acid and ammonia, and then directed to a hydride generator and a photochemical reactor to realize simultaneous hydride generation and photochemical vapor generation, respectively. Optimum conditions for dual-mode chemical vapor generation were carefully investigated. Under the optimized conditions, limits of detection of 0.05, 0.008, 0.8 and 0.1 ?g L(-1) were obtained for As, Cd, Fe and Ni, respectively. The precisions were 5.0, 5.5, 4.3 and 4.5% (n = 6, RSDs) for 2 ?g L(-1) of As, 1 ?g L(-1) of Cd, 50 ?g L(-1) of Fe and 10 ?g L(-1) of Ni, respectively. This method was validated for accuracy with three certified reference water samples and applied to the simultaneous determination of these elements in a tap water sample with spike recoveries in the range of 95-99%. PMID:24691520

Wang, Yu; Xu, Kailai; Jiang, Xiaoming; Hou, Xiandeng; Zheng, Chengbin

2014-04-15

366

Method for the removal and recovery of mercury  

SciTech Connect

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

367

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

368

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

369

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

Microsoft Academic Search

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

Arvind Sinha; Sunil Kumar Khare

370

Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD2  

Microsoft Academic Search

A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1molL?1 HCl for methyl mercury and 2molL?1 HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical

Mustafa Tuzen; Ozgur Dogan Uluozlu; Isa Karaman; Mustafa Soylak

2009-01-01

371

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

Microsoft Academic Search

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

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

2007-01-01

372

Ballistic Mercury orbiter mission via Venus and Mercury gravity assists  

NASA Astrophysics Data System (ADS)

This paper shows that it is possible to deliver a payload of 600 to 2000 kg to a 300-km circular orbit at Mercury, using the presently available NASA STS and a single-stage bipropellant chemical rocket. This superior payload performance is attained by swingbys of Venus, plus more importantly, the use of the reverse Delta-V/EGA process. In contrast to the familiar Delta-V/EGA process used to boost the launch energy by returning to earth for a gravity assist, the reverse process reduces the Mercury approach energy each time a spacecraft makes a near-resonant return to Mercury for a gravity assist and reduces the orbit-capture Delta-V requirement. The mission sequences for such high-performance missions are described, and example mission opportunities for the years 1990 to 2010 are presented.

Yen, Chen-Wan Liu

1989-09-01

373

Ballistic Mercury orbiter mission via Venus and Mercury gravity assists  

NASA Astrophysics Data System (ADS)

It is shown that it is possible to deliver a payload of 600 to 2000 kg to a 300-km circular orbit at Mercury using presently available NASA Space Transportation Systems and a single-stage bipropellant chemical rocket. This superior payload performance is attained by swingbys of Venus, plus (more importantly), the use of the reverse Delta-V/EGA process. In contrast to the Delta-V/EGA process (used to boost the launch energy by returning to earth for a gravity assist), the reverse Delta-V/EGA process reduces the Mercury approach energy each time a spacecraft makes a near-resonant return to Mercury for a gravity assist and reduces the orbit-capture Delta-V requirement. The mission sequences for such high-performance missions are described, and example mission opportunities for the years 1990 to 2010 are presented.

Yen, C.-W. L.

1986-08-01

374

The Thermal Evolution of Mercury  

NASA Astrophysics Data System (ADS)

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

Ziethe, Ruth

375

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

376

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...

377

R & D on mercury target pitting issue  

Microsoft Academic Search

A technical issue in mercury spallation target development is pitting, which appears on the target vessel in conjunction with the pressure wave. Pitting has been found in off-beam line test by split Hopkinson pressure bar (SHPB) test as well as in the on-beam test of mercury target at WNR of LANSCE. In SHPB tests pressure in mercury was reduced from

K. Kikuchi; H. Kogawa; M. Futakawa; S. Ishikura; M. Kaminaga; R. Hino

2003-01-01

378

Uptake of Mercury Vapor by Wheat  

PubMed Central

Using a whole-plant chamber and 203Hg-labeled mercury, a quantitative study was made of the effect of environmental parameters on the uptake, by wheat (Triticum aestivum), of metallic mercury vapor, an atmospheric pollutant. Factors were examined in relation to their influence on components of the gas-assimilation model, [Formula: see text] where U(Hg) is the rate of mercury uptake per unit leaf surface, Ca? is the ambient mercury vapor concentration, Cl? is the mercury concentration at immobilization sites within the plant (assumed to be zero), rl.Hg is the total leaf resistance to mercury vapor exchange, and rm.hg is a residual term to account for unexplained physical and biochemical resistances to mercury vapor uptake. Essentially all mercury vapor uptake was confined to the leaves. rl.hg was particularly influenced by illumination (0 to 12.8 klux), but unaffected by ambient temperature (17 to 33 C) and mercury vapor concentration (0 to 40 ?g m?3). The principal limitation to mercury vapor uptake was rm.hg, which was linearly related to leaf temperature, but unaffected by mercury vapor concentration and illumination, except for apparent high values in darkness. Knowing Ca? and estimating rl.hg and rm.hg from experimental data, mercury vapor uptake by wheat in light was accurately predicted for several durations of exposure using the above model.

Browne, Christopher L.; Fang, Sheng C.

1978-01-01

379

Mercury's Thermal Evolution, Dynamical Topography and Geoid  

Microsoft Academic Search

Among the terrestrial planets Mercury is not only the smallest, but also the densest (after correction for self-compression). To explain Mercury's high density it is considered likely that the planet's mantle was removed during a giant impact event, when proto-Mercury was already differentiated into an iron core and a silicate mantle. Beside the damage to the planet's mantle the vaporization

Ruth Ziethe; Johannes Benkhoff

2010-01-01

380

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

381

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

382

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...

383

Shedding some light on mercury lamps  

NSDL National Science Digital Library

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

Online, Environmental S.; Society, American C.

384

Kawasaki's disease, acrodynia, and mercury.  

PubMed

A superantigen or autoimmunity has been hypothesized to be the main cause of the Kawasaki's Disease but the etiology is unknown. Medical literature, epidemiological findings, and some case reports have suggested that mercury may play a pathogenic role. Several patients with Kawasaki's Disease have presented with elevated urine mercury levels compared to matched controls. Most symptoms and diagnostic criteria which are seen in children with acrodynia, known to be caused by mercury, are similar to those seen in Kawasaki's Disease. Genetic depletion of glutathione S-transferase , a susceptibility marker for Kawasaki's Disease, is known to be also a risk factor for acrodynia and may also increase susceptibility to mercury . Coinciding with the largest increase (1985-1990) of thimerosal (49.6% ethyl mercury) in vaccines, routinely given to infants in the U.S. by 6 months of age (from 75microg to 187.5microg), the rates of Kawasaki's Disease increased ten times, and, later (1985-1997), by 20 times. Since 1990 88 cases of patients developing Kawasaki's Disease some days after vaccination have been reported to the Centers of Disease Control (CDC) including 19% manifesting symptoms the same day. The presented pathogenetic model may lead to new preventive- and therapeutic strategies for Kawasaki's disease. PMID:19075648

Mutter, J; Yeter, D

2008-01-01

385

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

PubMed Central

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

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

2007-01-01

386

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

387

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

388

The Feedback Dynamo of Mercury  

NASA Astrophysics Data System (ADS)

The observed weakness of the magnetic field of planet Mercury poses a long-standing puzzle to dynamo theory. Since Mercury is the closest planet to the Sun, it is subject to an intense solar wind flow. This leads to a relatively strong external magnetic field from the magnetosphere compared to the internal field. We explore the conjecture that a negative feedback process of magnetospheric origin could damp the dynamo evolution of Mercury. We present results from numerical dynamo simulations demonstrating how it is possible to capture the dynamo in a weak state in a powering up phase already with a weak external field. The numerical simulation enables us to show how the dynamics inside the inaccessible core are altered by the feedback and how the transition to a strong field dynamo is inhibited. We conclude with a description of the outside characteristics of the feedback dynamo, which can be compared to satellite data.

Heyner, D.; Wicht, J.; Gomez Perez, N.; Schmitt, D.; Auster, U.; Glassmeier, K.

2012-12-01

389

Photomosaic of Mercury - Outbound View  

NASA Technical Reports Server (NTRS)

After passing on the darkside of the planet, Mariner 10 photographed the other, somewhat more illuminated hemisphere of Mercury. The north pole is at the top, two-thirds down from which is the equator.

The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

1974-01-01

390

Photomosaic of Mercury - Inbound View  

NASA Technical Reports Server (NTRS)

This is a mosaic of images taken of Mercury taken from 125,000 miles away. The tiny, brightly rayed crater (just below center top) was the first recognizable feature on the planet's surface and was named in memory of astronomer Gerard Kuiper, a Mariner 10 team member.

The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

1974-01-01

391

Optimisation of flow-injection-hydride generation inductively coupled plasma spectrometric determination of selenium in electrolytic manganese.  

PubMed

Flow-injection-hydride generation procedure for Se in electrolytic manganese was optimized by means of the experimental design approach. Instrumental variables like power supplied (P), sample (F) and argon (G) flow rates together with chemical variables like NaBH(4) and HCl concentrations were studied. In case of the chemical variables, it was concluded that sodium tetrahydridoborate concentrations higher than 1.0% extinguished the plasma while HCl concentration should always be higher than 0.6moldm(-3). The analysis of effects suggested that all the instrumental variables are significant factors, and the optimum conditions were P=1550W, F=4.75mLmin(-1) and G=0.6mLmin(-1). The influence of Mn was specially studied and it was concluded that the interferences were negligible if Mn is below 2.0gL(-1). In the same sense, the interferences of antimony(III), arsenic(V) and mercury(II) were also considered negligible. Finally, a detection limit of 0.0005% (w/w) was obtained (a repeatability R.S.D. <2.0% for all Se concentrations tried). Some manganese samples were also spiked with different concentrations of Se(IV) and the results demonstrated to be in good statistical agreement with expected values. PMID:18969933

Etxebarria, N; Antolín, R; Borge, G; Posada, T; Raposo, J C

2005-03-15

392

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

393

Determination of Arsenic in Food Samples by Hydride Generation – Atomic Absorption Spectrometry  

Microsoft Academic Search

A method for the determination of trace amounts of arsenic in food samples using flow injection analysis and atomic absorption spectrometry with hydride generation (FI-HG AAS) was developed. The parameters of the flow injection system and the hydride generation were optimized with respect to reagent concentrations, atomization temperature, injection volume, reaction coil length and carrier flow rate. The limits of

Aloísia Laura Moretto; Solange Cadore

2004-01-01

394

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

Microsoft Academic Search

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.

Ragaiy Zidan; James A. Ritter; Armin D. Ebner; Jun Wang; Charles E. Holland

2008-01-01

395

Elementquerstörungen bei der spurenanalytischen Selen-Bestimmung nach dem Hydrid-AAS-Verfahren  

Microsoft Academic Search

The sodium boro hydride-reduction method for the liberation of selenium from acid sample solutions in connection with its determination by AAS using a heatable optical cell made of quartz (hydride system MHS-1, Bodenseewerk Perkin-Elmer, Überlingen, F.R.G.) is interfered with by numerous concomitant elements occurring even in the trace range in the sample solution.

A. Meyer; Ch. Hofer; G. Tölg; S. Raptis; G. Knapp

1979-01-01

396

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

Microsoft Academic Search

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

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

2007-01-01

397

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

NASA Astrophysics Data System (ADS)

The development and demonstration of a metal hydride/chemical heat pump (MHHP) is reported. In the design of the MHHP, heat transfer was considered to be the key technical study area. Therefore, the goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger/containment assembly. Phase II consisted of the experimental verification of the hydride alloy design data, fabrication of the hydride heat exchanger module components, heat transfer testing of a single heat exchanger element and preliminary performance testing of the entire module. In Phase II, two hydride heat exchanger modules were constructed. Each module consistes of 14 finned copper tubes in a staggered tube bundle arrangement enclosed in a cylindrical pressure vessel. The hydride powder is stored in the annular spacing between the fins. The heat transfer media, water, flows through the finned tubes. Insulation thermally isolates the tubes and hydride materials from the high mass pressure vessel. A single metallic filter in each vessel prevents hydride migrating from one vessel to another

Argabright, T. A.

1983-09-01

398

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

399

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

400

Blood and Tissue Selenium Determination by Hydride Generation Atomic Absorption Spectrophotometry  

Microsoft Academic Search

Pechová A., L. Pavlata, J. Illek: Blood and Tissue Selenium Determination by Hydride Generation Atomic Absorption Spectrophotometry. Acta Vet. Brno 2005, 74: 483-490. The aim of the study was to optimize the method of blood and tissue selenium determination in ruminants, and to implement it in research and diagnostic practice. A method was developed for selenium determination by hydride generation

A. PECHOVÁ; L. PAVLATA; J. ILLEK

401

Insertion and reduction chemistry of isocyanide with a cyclometalated ditantalum hydride complex.  

PubMed

Reaction of a ditantalum hydride complex with isocyanide is reported. The hydride complex underwent single and double isocyanide insertion into Ta-H bonds, giving iminoformyl and imine-iminoacyl complexes. The transformation of the iminoformyl complex into the amido-carbyne complex was also observed. PMID:21344109

Watanabe, Takahito; Kurogi, Takashi; Ishida, Yutaka; Kawaguchi, Hiroyuki

2011-08-14

402

Hydrogen desorption kinetics from zirconium hydride and zirconium metal in vacuum  

NASA Astrophysics Data System (ADS)

The kinetics of hydrogen desorption from zirconium hydride is important in many nuclear design and safety applications. In this paper, a coordinated experimental and modeling study has been used to explicitly demonstrate the applicability of existing kinetic theories for hydrogen desorption from zirconium hydride and ?-zirconium. A static synthesis method was used to produce ?-zirconium hydride, and the crystallographic phases of the zirconium hydride were confirmed by X-ray diffraction (XRD). Three obvious stages, involving ?-zirconium hydride, a two-phase region, and ?-zirconium, were observed in the hydrogen desorption spectra of two zirconium hydride specimens with H/Zr ratios of 1.62 and 1.64, respectively, which were obtained using thermal desorption spectroscopy (TDS). A continuous, one-dimensional, two-phase moving boundary model, coupled with the zero- and second-order kinetics of hydrogen desorption from ?-zirconium hydride and ?-zirconium, respectively, has been developed to reproduce the TDS experimental results. A comparison of the modeling predictions with the experimental results indicates that a zero-order kinetic model is valid for description of hydrogen flux away from the ?-hydride phase, and that a second-order kinetic model works well for hydrogen desorption from ?-Zr if the activation energy of desorption is optimized to be 70% of the value reported in the literature.

Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.

2014-05-01

403

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

404

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

405

Storage of Hydrogen in the Form of Metal Hydrides: An Application to Thermal Engines.  

National Technical Information Service (NTIS)

The possibility of using LaNi56, FeTiH2, or MgH2 as metal hydride storage systems for hydrogen fueled automobile engines is discussed. Magnesium copper and magnesium nickel hydrides studies indicate that they provide more stable storage systems than pure ...

C. Gales P. Perroud

1981-01-01

406

Formation of Mercury's smooth plains  

SciTech Connect

Indirect evidence is presented for a volcanic origin in the case of two smooth plains on Mercury, the Borealis Planitia and the Hilly and Lineated Terrain. These results, in conjunction with those previously obtained for the circum-Caloris plains and the Tolstoj basin, indicate that smooth plains volcanism was a global process on Mercury. It is further suggested that the smooth and intercrater plains may have resulted from two separate volcanic episodes, with smooth plains volcanism being a consequence of Caloris impact-triggering. 45 references.

Kiefer, W.S.; Murray, B.C.

1987-12-01

407

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

408

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

409

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

SciTech Connect

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

Not Available

1990-01-01

410

[Application of mercury-resistant genes in bioremediation of mercurials in environments].  

PubMed

Mercury and its organic compounds, especially methylmercury are extremely hazardous pollutants that have been released into the environment in substantial quantities by natural events and anthropogenic activities. Due to the acute toxicity of these contaminants, there is an urgent need to develop an effective and affordable technology to remove them from the environments. Recently, attempts have been made to utilize bacterial mer operon-mediated reduction and volatilization of mercurials for environmental remediation of mercury pollution. However, application of this technology to the treatment of mercury-contaminated environments has been limited by social concerns about the release of volatile mercury that will become part of the local mercury cycle and repollute the environment again, into the ambient air. To improve this environmental problem, a new mercury scavenging mechanism that could be expressed in living cells and accumulates mercury from contaminated site without releasing mercury vapor is necessitated. To construct a new biocatalyst that is capable of specifically accumulating mercury from contaminated sites without releasing mercury vapor, we have genetically engineered bacteria and tobacco plant for removal of mercury from wastewater and soils, respectively, to express a mercury transport system and organomercurial lyase enzyme simultaneously, and overexpress polyphosphate, a chelator of divalent metals. The applicability of these new engineered biocatalysts in the environmental remediation of mercurials is evaluated and discussed in this review. PMID:20823672

Pan-Hou, Hidemitsu

2010-09-01

411

Cases of mercury exposure, bioavailability, and absorption.  

PubMed

Mercury is a unique element that, unlike many metals, has no essential biological function. It is liquid at room temperature and is 13.6 times heavier than water. Its unique physical properties have been exploited for a variety of uses such as in mercury switches, thermostats, thermometers, and other instruments. Its ability to amalgamate with gold and silver are used in mining these precious metals and as a dental restorative. Its toxic properties have been exploited for medications, preservatives, antiseptics, and pesticides. For these reasons there have been many industrial uses of mercury, and occupational exposures of workers and industrial emissions and effluents contaminating air, water, soil, and ultimately food chains have long been a matter of great public health concern. This paper examines briefly six cases representing various forms of exposure to different species of mercury, and indicates the methodological issues in estimating exposure, bioavailability and absorption; these cases include Minamata disease in Japan, organic mercury poisoning in Iraq, methylmercury (MeHg) exposure in the Amazon, dimethylmercury (PMM) in the laboratory, an elemental mercury spill in Cajamarca, Peru, and a mercury-contaminated building in Hoboken, NJ, USA. Other scenarios that are not described include occupational exposure to mercury salts, mercurial preservatives in vaccines, cultural and ritualistic uses of mercury, and mercury in dental amalgams. PMID:12915150

Gochfeld, Michael

2003-09-01

412

Dental amalgam, mercury toxicity, and renal autoimmunity.  

PubMed

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

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

2008-01-01

413

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

414

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

415

Structure and properties of metal hydrides prepared by mechanical alloying  

SciTech Connect

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

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

1995-09-01

416

BIOMEDICAL ASPECTS OF EXPOSURE TO MERCURY AND ORGANIC MERCURY COMPOUNDS  

Microsoft Academic Search

FORWARD: Thimerosal or merthiolate is a derivative of thiolsalicylate where ethyl- mercury is attached though the sulfur or thiol group. Thimerosal was first synthesized to make a water soluble form of ethylmercury, which had potent bacterial static properties, but was very insoluble in water. Thimerosal is now used as a preservative or anti- microbial in certain medicinals. This anti-microbial action

BOYD E. HALEY

417

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

418

Hydrogen concentration depth profiles and superconductivity in the palladium copper hydride system  

SciTech Connect

A sample configuration has been devised to study palladium copper hydride alloys with respect to hydrogen concentration depth profiles; and superconducting parameters. Superconducting palladium copper hydride samples, which displayed transition temperatures in agreement with data measured by Stritzker, were obtained. Thin palladium copper alloy films, which were formed on top of palladium substrate foils by ion beam and solid state techniques, were hydrogenized using electrolysis, hydrogen gas pressure charging and hydrogen ion implantation. The thin palladium copper surface films proved permeable to hydrogen, which was present in higher near surface concentrations as expected by literature. Correlation of critical superconducting transition temperature data to hydrogen concentration depth profiles was obtained. In situ measurements displayed a transition of a palladium copper hydride sample from the normal metallic to the superconducting state upon annealing treatment. Alloy structure, a parameter so far neglected by literature was determined to be significant for the formation of superconducting palladium hydride as well as palladium copper hydride.

Leiberich, A.

1983-01-01

419

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

420

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

421

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

422

How does climate change influence Arctic mercury?  

PubMed

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

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

2012-01-01

423

Accumulation of mercury by Azolla and its effect on growth  

Microsoft Academic Search

Although mercury and mercurial compounds had been known as toxic substances, the hazards caused by them received world-wide recognition after the outbreak of the Minamata Bay disease in Japan. Since then a lot of research has been clone to discover the sources of mercury in the environment and the modes of interaction of mercury and mercurial compounds with various organisms.

B. B. Mishra; D. R. Nanda; B. N. Misra

1987-01-01

424

Abatement of Gas-Phase Mercury—Recent Developments  

Microsoft Academic Search

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

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

2012-01-01

425

Thermal Emission Spectra of Mercury  

NASA Technical Reports Server (NTRS)

The emission spectrum of Mercury may hold clues as to the mineral composition of the surface from reststrahlen bands. Unfortunately, these bands are very weak in finely powdered materials, such as are expected on the mercurian surface, and they lie in a region of the spectrum where there are substantial atmospheric absorptions. We have been measuring the 8-14-micron spectra of Mercury and the Sun at a resolution of about 0.03 wavenumbers, using the Fourier Transform Spectrometer (FTS) located at the National Solar Observatory, Kitt Peak, Arizona. The objective of using such a high resolution for the measurement is to be able to look between atmospheric absorption lines as much as possible. The atmospheric effects are largely cancelled by ratioing Mercury spectra to Sun spectra taken at nearly the same airmass, although small differences in airmass produce some residual atmospheric absorptions in the ratio spectra. We expect that spectral features of Mercury, if any, should appear in the ratio spectra, since the 8-14 micron spectrum of the Sun approximates a black body.

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

1999-01-01

426

Mercury Telluride and Cadmium Telluride  

NASA Technical Reports Server (NTRS)

A semiconductor's usefulness is determined by how atoms are ordered within the crystal's underlying three-dimensional structure. While this mercury telluride and cadmium telluride alloy sample mixes completely in Earth -based laboratories, convective flows prevent them from mixing uniformly. In space, the ingredients mix more homogenously, resulting in a superior product.

2004-01-01

427

PERCEPTION OF MERCURY RISK INFORMATION  

EPA Science Inventory

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

428

Relativity and the mercury battery.  

PubMed

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

Zaleski-Ejgierd, Patryk; Pyykkö, Pekka

2011-10-01

429

Optical Studies of Radioactive Mercury  

Microsoft Academic Search

A technique has been developed for studying the hyperfine structure of the resonance radiation of mercury. A single Zeeman component of the 2536 A line of Hg198 is used as a variable-frequency monochromatic light source, and the field strength applied to the arc lamp to produce resonance absorption in a resonance lamp is a measure of the resonance frequency. Natural

F. Bitter; S. P. Davis; B. Richter; J. E. Young

1954-01-01

430

MODELING MERCURY IN STREAM ECOSYSTEMS  

EPA Science Inventory

Mercury is a classic multimedia pollutant. Natural and anthropogenic emissions are driven by a complicated set of transport and transformation reactions operating on a variety of scales in the atmosphere, landscape, surface water, and biota. In the past 15 years, surface water me...

431

Partition and Tempospatial Variation of Gaseous and Particulate Mercury at a Unique Mercury-Contaminated Remediation Site  

Microsoft Academic Search

This study investigated the seasonal variation and spatial distribution of gaseous and particulate mercury at a unique mercury-contaminated remediation site located at the near-coastal region of Tainan City, Taiwan. Gaseous elemental mercury (GEM), particulate mercury (PTM), and dustfall mercury (DFM) were measured at six nearby sites from November 2009 to September 2010. A newly issued Method for Sampling and Analyzing

Yi-Hsiu Jen; Chung-Shin Yuan; Yuan-Chung Lin; Chang-Gai Lee; Chung-Hsuang Hung; Cheng-Mou Tsai; Hsieh-Hung Tsai; Iau-Ren Ie

2011-01-01

432

40 CFR Appendix Xiii to Part 266 - Mercury Bearing Wastes That May Be Processed in Exempt Mercury Recovery Units  

Code of Federal Regulations, 2010 CFR

...Processed in Exempt Mercury Recovery Units These are exempt mercury-bearing materials...261, appendix VIII organic constituents when...manufacturers or users of mercury or mercury products...wastewater treatment plant sludge and filter...mercury contained in soil [59 FR...

2010-07-01

433

40 CFR Appendix Xiii to Part 266 - Mercury Bearing Wastes That May Be Processed in Exempt Mercury Recovery Units  

Code of Federal Regulations, 2010 CFR

...Processed in Exempt Mercury Recovery Units These are exempt mercury-bearing materials...261, appendix VIII organic constituents when...manufacturers or users of mercury or mercury products...wastewater treatment plant sludge and filter...mercury contained in soil [59 FR...

2009-07-01

434

The Plasma Environment at Mercury  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

435

First-principles modelling of magnesium titanium hydrides  

NASA Astrophysics Data System (ADS)

Mixing Mg with Ti leads to a hydride MgxTi(1 - x)H2 with markedly improved (de)hydrogenation properties for x\\lesssim 0.8 , as compared to MgH2. Optically thin films of MgxTi(1 - x)H2 have a black appearance, which is remarkable for a hydride material. In this paper we study the structure and stability of MgxTi(1 - x)H2, x = 0-1 by first-principles calculations at the level of density functional theory. We give evidence for a fluorite to rutile phase transition at a critical composition xc = 0.8-0.9, which correlates with the experimentally observed sharp decrease in (de)hydrogenation rates at this composition. The densities of states of MgxTi(1 - x)H2 have a peak at the Fermi level, composed of Ti d states. Disorder in the positions of the Ti atoms easily destroys the metallic plasma, however, which suppresses the optical reflection. Interband transitions result in a featureless optical absorption over a large energy range, causing the black appearance of MgxTi(1 - x)H2.

Er, Süleyman; van Setten, Michiel J.; de Wijs, Gilles A.; Brocks, Geert

2010-02-01

436

Hydriding of TiZrNiFe nanocompounds  

NASA Astrophysics Data System (ADS)

Ti-based quasicrystals belong to the second largest group of the stable quasicrystals, showing attractive properties as hydrogen storage materials. The Ti 45Zr 38Ni 17 intermetallic compound forms an icosahedral ( i-phase) structure, in which Ti and Zr atoms possess very good chemical affinity for hydrogen absorption. We modified the Ti 45Zr 38Ni 17 compounds by substituting 3d metals (iron) for Ni to obtain amorphous phase. The samples were produced by mechanical alloying. The 3d metal atoms are located in the same positions as nickel. The structural characterization was made by means of XRD measurements. Thermodynamic properties were studied by differential scanning calorimetry (DSC) and thermal desorption spectroscopy (TDS). The obtained amorphous phases Ti 45Zr 38Ni (9,13)Fe (8,4) transform to the i-phase at the similar temperature range as Ti 45Zr 38Ni 17. The final concentration of absorbed hydrogen depends on the amount of Fe. When increasing the amount of iron, the hydrogen release temperature becomes lower. After hydriding, the samples decompose into simple metal hydrides.

?ywczak, A.; Shinya, Daigo; Gondek, ?.; Takasaki, Akito; Figiel, H.

2010-01-01

437

GAS-PHASE REACTIONS OF HYDRIDE ANION, H{sup -}  

SciTech Connect

Rate constants were measured at 300 K for the reactions of the hydride anion, H{sup -}, with neutral molecules C{sub 2}H{sub 2}, H{sub 2}O, CH{sub 3}CN, CH{sub 3}OH, (CH{sub 3}){sub 2}CO, CH{sub 3}CHO, N{sub 2}O, CO{sub 2}, O{sub 2}, CO, CH{sub 3}Cl, (CH{sub 3}){sub 3}CCl, (CH{sub 3}CH{sub 2}){sub 2}O, C{sub 6}H{sub 6}, and D{sub 2} 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{sup -} 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; Yang Zhibo; Demarais, Nicholas J.; Bierbaum, Veronica M. [Department of Chemistry and Biochemistry, 215 UCB, University of Colorado, Boulder, CO 80309-0215 (United States); Snow, Theodore P., E-mail: Oscar.Martinez@colorado.ed, E-mail: Zhibo.Yang@colorado.ed, E-mail: Nicholas.Demarais@colorado.ed, E-mail: Veronica.Bierbaum@colorado.ed, E-mail: Theodore.Snow@colorado.ed [Department of Astrophysical and Planetary Sciences, 391 UCB, University of Colorado, Boulder, CO 80309-0391 (United States)

2010-09-01

438

Physics of Hydrogen Storage in Metal-Hydrides  

NASA Astrophysics Data System (ADS)

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

Abdelfattah-Zidan, Ragaiy

439

ACCEPTABILITY ENVELOPE FOR METAL HYDRIDE-BASED HYDROGEN STORAGE SYSTEMS  

SciTech Connect

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

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

2011-07-18

440

Interferences in electrochemical hydride generation of hydrogen selenide  

NASA Astrophysics Data System (ADS)

Interferences from Cu(II), Zn(II), Pt(IV), As(III) and nitrate on electrochemical hydride generation of hydrogen selenide were studied using a tubular flow-through generator, flow injection sample introduction and quartz tube atomic absorption spectrometry. Comparison with conventional chemical generation using tetrahydroborate was also performed. Lead and reticulated vitreous carbon (RVC), both in particulate form, were used as cathode materials. Signal supressions up to 60-75%, depending on the cathode material, were obtained in the presence of up to 200 mg l-1 of nitrate due to the competitive reduction of the anion. Interference from As(III) was similar in electrochemical and chemical generation, being related to the quartz tube atomization process. Zinc did not interfere up to Se/Zn ratios 1:100, whereas copper and platinum showed suppression levels up to 50% for Se/interferent ratios 1:100. Total signal suppression was observed in presence of Se/Cu ratios 1:100 when RVC cathodes were used. No memory effects were observed in any case. Scanning electron microscopy and squared wave voltametry studies supported the interference mechanism based on the decomposition of the hydride on the dispersed particles of the reduced metal.

Bolea, E.; Laborda, F.; Belarra, M. A.; Castillo, J. R.

2001-12-01

441

Relativistic DMRG calculations on the curve crossing of cesium hydride.  

PubMed

Over the past few years, it has been shown in various studies on small molecules with only a few electrons that the density-matrix renormalization group (DMRG) method converges to results close to the full configuration-interaction limit for the total electronic energy. In order to test the capabilities of the method for molecules with complex electronic structures, we performed a study on the potential-energy curves of the ground state and the first excited state of 1sigma+ symmetry of the cesium hydride molecule. For cesium relativistic effects cannot be neglected, therefore we have used the generalized arbitrary-order Douglas-Kroll-Hess protocol up to tenth order, which allows for a complete decoupling of the Dirac Hamiltonian. Scalar-relativistic effects are thus fully incorporated in the calculations. The potential curves of the cesium hydride molecule feature an avoided crossing between the ground state and the first excited state, which is shown to be very well described by the DMRG method. Compared to multireference configuration-interaction results, the potential curves hardly differ in shape, for both the ground state and the excited state, but the total energies from the DMRG calculations are in general consistently lower. However, the DMRG energies are as accurate as corresponding coupled cluster energies at the equilibrium distance, but convergence to the full configuration-interaction limit is not achieved. PMID:16292897

Moritz, Gerrit; Wolf, Alexander; Reiher, Markus

2005-11-01

442

Mercury (micro)biogeochemistry in polar environments.  

PubMed

The contamination of polar regions with mercury that is transported as inorganic mercury from lower latitudes has resulted in the accumulation of methylmercury in the food chain of polar environments, risking the health of humans and wildlife. This problem is likely to be particularly severe in coastal marine environments where active cycling occurs. Little is currently known about how mercury is methylated in polar environments. Relating observations on mercury deposition and transport through polar regions to knowledge of the microbiology of cold environments and considering the principles of mercury transformations as have been elucidated in temperate aquatic environments, we propose that in polar regions (1) variable pathways for mercury methylation may exist, (2) mercury bioavailability to microbial transformations may be enhanced, and (3) microbial niches within sea ice are sites where active microorganisms are localized in proximity to high concentrations of mercury. Thus, microbial transformations, and consequently mercury biogeochemistry, in the Arctic and Antarctic are both unique and common to these processes in lower latitudes, and understanding their dynamics is needed for the management of mercury-contaminated polar environments. PMID:17199802

Barkay, Tamar; Poulain, Alexandre J

2007-02-01

443

Mercury exposure from interior latex paint  

SciTech Connect

Many paint companies have used phenylmercuric acetate as a preservative to prolong the shelf life of interior latex paint. In August 1989, acrodynia, a form of mercury poisoning, occurred in a child exposed to paint fumes in a home recently painted with a brand containing 4.7 mmol of mercury per liter (at that time the Environmental Protection Agency's recommended limit was 1.5 mmol or less per liter). To determine whether the recent use of that brand of paint containing phenylmercuric acetate was associated with elevated indoor-air and urinary mercury concentrations, we studied 74 exposed persons living in 19 homes recently painted with the brand and 28 unexposed persons living in 10 homes not recently painted with paint containing mercury. The paint samples from the homes of exposed persons contained a median of 3.8 mmol of mercury per liter, and air samples from the homes had a median mercury content of 10.0 nmol per cubic meter (range, less than 0.5 to 49.9). No mercury was detected in paint or air samples from the homes of unexposed persons. The median urinary mercury concentration was higher in the exposed persons (4.7 nmol of mercury per millimole of creatinine; range, 1.4 to 66.5) than in the unexposed persons (1.1 nmol per millimole; range, 0.02 to 3.9; P less than 0.001). Urinary mercury concentrations within the range that we found in exposed persons have been associated with symptomatic mercury poisoning. We found that potentially hazardous exposure to mercury had occurred among persons whose homes were painted with a brand of paint containing mercury at concentrations approximately 2 1/2 times the Environmental Protection Agency's recommended limit.

Agocs, M.M.; Etzel, R.A.; Parrish, R.G.; Paschal, D.C.; Campagna, P.R.; Cohen, D.S.; Kilbourne, E.M.; Hesse, J.L. (Centers for Disease Control, Atlanta, GA (USA))

1990-10-18

444

Mercury volatilization from salt marsh sediments  

NASA Astrophysics Data System (ADS)

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

Smith, Lora M.; Reinfelder, John R.

2009-06-01

445

Mercury emissions from municipal solid waste combustors  

SciTech Connect

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

Not Available

1993-05-01

446

RECOVERY OF MERCURY FROM CONTAMINATED LIQUID WASTES  

SciTech Connect

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

Robin M. Stewart

1999-09-29

447

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

Code of Federal Regulations, 2013 CFR

...mercury is a component part, such as manometers, pumps, thermometers, switches, etc. (for electron tubes, m