Sample records for water noble gases

  1. Noble Gases in Lakes and Ground Waters


    Kipfer, Rolf; Aeschbach-Hertig, Werner; Peeters, Frank; Stute, Marvin


    In contrast to most other fields of noble gas geochemistry that mostly regard atmospheric noble gases as 'contamination,' air-derived noble gases make up the far largest and hence most important contribution to the noble gas abundance in meteoric waters, such as lakes and ground waters. Atmospheric noble gases enter the meteoric water cycle by gas partitioning during air / water exchange with the atmosphere. In lakes and oceans noble gases are exchanged with the free atmosphere at the surface...

  2. Recent Experimental Advances to Determine (noble) Gases in Waters (United States)

    Kipfer, R.; Brennwald, M. S.; Huxol, S.; Mächler, L.; Maden, C.; Vogel, N.; Tomonaga, Y.


    In aquatic systems noble gases, radon, and bio-geochemically conservative transient trace gases (SF6, CFCs) are frequently applied to determine water residence times and to reconstruct past environmental and climatic conditions. Recent experimental breakthroughs now enable ● to apply the well-established concepts of terrestrial noble gas geochemistry in waters to the minute water amounts stored in sediment pore space and in fluid inclusions (A), ● to determine gas exchange processes on the bio-geochemical relevant time scales of minutes - hours (B), and ● to separate diffusive and advective gas transport in soil air (C). A. Noble-gas analysis in water samples (techniques that combine crushing and sieving speleothem samples in ultra-high-vacuum to a specific grain size allow to separate air and water-bearing fluid inclusions and thus enables noble-gas-based reconstruction of environmental conditions from water masses as small as 1mg [2]. B. The coupling of noble gas analysis with approaches of gas chromatography permits combined analysis of noble gases and other gases species (e.g., SF6, CFCs, O2, N2) from a single water sample. The new method substantially improves ground water dating by SF6 and CFCs as excess air is quantified from the same sample and hence can adequately be corrected for [3]. Portable membrane-inlet mass spectrometers enable the quasi-continuous and real-time analysis of noble gases and other dissolved gases directly in the field, allowing, for instance, quantification of O2 turnover rates on small time scales [4]. C. New technical developments perfect 222Rn analysis in water by the synchronous the determination of the short-lived 220Rn. The combined 220,222Rn analysis sheds light on the emanation behaviour of radon by identifying soil water content to be the crucial control of 220Rn occurrence in the environment, e.g., making an argument why 220Rn is not detectable in water, but in soil air. As 220Rn occurrence is of 'very local origin

  3. Planetary noble gases (United States)

    Zahnle, Kevin


    An overview of the history and current status of research on planetary noble gases is presented. The discovery that neon and argon are vastly more abundant on Venus than on earth points to the solar wind rather than condensation as the fundamental process for placing noble gases in the atmospheres of the terrestrial planets; however, solar wind implantation may not be able to fully reproduce the observed gradient, nor does it obviously account for similar planetary Ne/Ar ratios and dissimilar planetary Ar/Kr ratios. More recent studies have emphasized escape rather than accretion. Hydrodynamic escape, which is fractionating, readily accounts for the difference between atmospheric neon and isotopically light mantle neon. Atmospheric cratering, which is nearly nonfractionating, can account for the extreme scarcity of nonradiogenic noble gases (and other volatiles) on Mars.

  4. Adsorption of Dissolved Gases (CH4, CO2, H2, Noble Gases) by Water-Saturated Smectite Clay Minerals (United States)

    Bourg, I. C.; Gadikota, G.; Dazas, B.


    Adsorption of dissolved gases by water-saturated clay minerals plays important roles in a range of fields. For example, gas adsorption in on clay minerals may significantly impact the formation of CH4 hydrates in fine-grained sediments, the behavior of CH4 in shale, CO2 leakage across caprocks of geologic CO2 sequestration sites, H2 leakage across engineered clay barriers of high-level radioactive waste repositories, and noble gas geochemistry reconstructions of hydrocarbon migration in the subsurface. Despite its importance, the adsorption of gases on clay minerals remains poorly understood. For example, some studies have suggested that clay surfaces promote the formation of CH4 hydrates, whereas others indicate that clay surfaces inhibit the formation of CH4 hydrates. Here, we present molecular dynamics (MD) simulations of the adsorption of a range of gases (CH4, CO2, H2, noble gases) on clay mineral surfaces. Our results indicate that the affinity of dissolved gases for clay mineral surfaces has a non-monotone dependence on the hydrated radius of the gas molecules. This non-monotone dependence arises from a combination of two effects: the polar nature of certain gas molecules (in particular, CO2) and the templating of interfacial water structure by the clay basal surface, which results in the presence of interfacial water "cages" of optimal size for intermediate-size gas molecules (such as Ne or Ar).

  5. Trapped noble gases in meteorites (United States)

    Swindle, Timothy D.


    The trapped noble gases in meteorites come in two main varieties, usually referred to as solar and planetary. The solar noble gases are implanted solar-wind or solar-flare materials, and thus their relative elemental abundances provide a good estimate of those of the sun. The planetary noble gases have relative elemental abundances similar to those in the terrestrial atmosphere, but there are also important distinctions. At least one other elemental pattern (subsolar) and several isotopic patterns have also been identified.

  6. Collisions of noble gases with supercooled sulfuric acid-water solutions. (United States)

    Behr, Peter; Scharfenort, Ulrich; Zellner, Reinhard


    The collisions of hyperthermal noble gases (He, Ne, Ar, Kr, Xe) with supercooled binary sulfuric acid-water mixtures (57-77 wt%) were explored in the temperature range between 210 and 240 K. The experiments were performed by directing a molecular beam of the respective gases onto a continuously renewed liquid surface and monitoring the velocity of the scattered molecules by mass spectrometry. Depending on the initial translational energies and molecular masses, we observe both inelastic scattering from the surface as well as thermalization followed by subsequent desorption. The experiments indicate that the repulsive momentum transfer in the inelastic scattering channel increases with increasing mass of the impinging gas, while it is only weakly affected by the initial velocities. The final energy of the thermally desorbing atoms can always be approximated by a Maxwell-Boltzmann distribution equal to the liquid bulk phase temperature. The influence of the binary composition of the liquid phase is only noticeable in the case of Ne, whilst this dependence diminishes for gases with molecular masses >or=40 amu. The probability of thermalisation relative to inelastic scattering increases with the bulk phase temperature, independent of the molecular masses of the colliding gas. In contrast, the fractional energy transfer during collision does not increase with temperature, except for Neon. These results can be interpreted in the model framework of hard-sphere collisions of noble gases with the surface, during which water and sulfuric acid molecules interact independently with the impinging gas.

  7. A membrane inlet mass spectrometry system for noble gases at natural abundances in gas and water samples. (United States)

    Visser, Ate; Singleton, Michael J; Hillegonds, Darren J; Velsko, Carol A; Moran, Jean E; Esser, Bradley K


    Noble gases dissolved in groundwater can reveal paleotemperatures, recharge conditions, and precise travel times. The collection and analysis of noble gas samples are cumbersome, involving noble gas purification, cryogenic separation and static mass spectrometry. A quicker and more efficient sample analysis method is required for introduced tracer studies and laboratory experiments. A Noble Gas Membrane Inlet Mass Spectrometry (NG-MIMS) system was developed to measure noble gases at natural abundances in gas and water samples. The NG-MIMS system consists of a membrane inlet, a dry-ice water trap, a carbon-dioxide trap, two getters, a gate valve, a turbomolecular pump and a quadrupole mass spectrometer equipped with an electron multiplier. Noble gases isotopes (4)He, (22)Ne, (38)Ar, (84)Kr and (132)Xe are measured every 10 s. The NG-MIMS system can reproduce measurements made on a traditional noble gas mass spectrometer system with precisions of 2%, 8%, 1%, 1% and 3% for He, Ne, Ar, Kr and Xe, respectively. Noble gas concentrations measured in an artificial recharge pond were used to monitor an introduced xenon tracer and to reconstruct temperature variations to within 2 °C. Additional experiments demonstrated the capability to measure noble gases in gas and in water samples, in real time. The NG-MIMS system is capable of providing analyses sufficiently accurate and precise for introduced noble gas tracers at managed aquifer recharge facilities, groundwater fingerprinting based on excess air and noble gas recharge temperature, and field and laboratory studies investigating ebullition and diffusive exchange. Copyright © 2013 John Wiley & Sons, Ltd.

  8. Simultaneous analysis of noble gases, sulfur hexafluoride, and other dissolved gases in water. (United States)

    Brennwald, Matthias S; Hofer, Markus; Kipfer, Rolf


    We developed an analytical method for the simultaneous measurement of dissolved He, Ne, Ar, Kr, Xe, SF6, N2, and O2 concentrations in a single water sample. The gases are extracted from the water using a head space technique and are transferred into a vacuum system for purification and separation into different fractions using a series of cold traps. Helium is analyzed using a quadrupole mass spectrometer (QMS). The remaining gas species are analyzed using a gas chromatograph equipped with a mass spectrometer (GC-MS) for analysis of Ne, Ar, Kr, Xe, N2, and O2 and an electron capture detector (GC-ECD) for SF6 analysis. Standard errors of the gas concentrations are approximately 8% for He and 2-5% for the remaining gas species. The method can be extended to also measure concentrations of chlorofluorocarbons (CFCs). Tests of the method in Lake Lucerne (Switzerland) showed that dissolved gas concentrations agree with measurements from other methods and concentrations of air saturated water. In a small artificial pond, we observed systematic gas supersaturations, which seem to be linked to adsorption of solar irradiation in the pond and to water circulation through a gravel bed.

  9. Noble Gases as Mantle Tracers (United States)

    Hilton, D. R.; Porcelli, D.


    The study of the noble gases has been associated with some of the most illustrious names in experimental science, and some of the most profound discoveries. Fundamental advances in nuclear chemistry and physics - including the discovery of isotopes - have resulted from their study, earning Nobel Prizes for a number of early practitioners (Rutherford in 1908; Soddy in 1921; Aston in 1922) as well as for their discoverers (Ramsay and Rayleigh in 1904). Within the Earth Sciences, the noble gases found application soon after discovery - helium was used as a chronometer to estimate formation ages of various minerals (Strutt, 1908). In more recent times, the emphasis of noble gas research has shifted to include their exploitation as inert tracers of geochemical processes. In large part, this shift stems from the realization that primordial volatiles have been stored within the Earth since the time of planetary accretion and are still leaking to the surface today. In this introduction, we give a brief overview of the discovery of the noble gases and their continuing utility in the Earth Sciences, prior to setting into perspective the present contribution, which focuses on noble gases in the Earth's mantle.

  10. Fractionated Noble Gases in Martian Meteorite ALH 84001 — An Indicator for Water-Rock Interaction, or a Sample of Ancient Atmosphere? (United States)

    Schwenzer, S. P.; Bart, G.; Bridges, J. C.; Crowther, S. A.; Filiberto, J.; Gilmour, J. D.; Herrmann, S.; Hicks, L. J.; Kelley, S. P.; Miller, M. A.; Ott, U.; Steer, E. D.; Swindle, T. D.; Treiman, A. H.


    Noble gases in the nakhlite and ALH84001 Martian meteorites are still a mystery, but could tell us about either the history of the Martian atmosphere, Martian water rock interaction or - likely - both!

  11. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales. (United States)

    Darrah, Thomas H; Vengosh, Avner; Jackson, Robert B; Warner, Nathaniel R; Poreda, Robert J


    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ(13)C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., (4)He, (20)Ne, (36)Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, (4)He) were significantly higher (P gases (air-saturated water; e.g., N2, (36)Ar) were significantly lower (P Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing.

  12. Noble gases in meteorites and terrestrial planets (United States)

    Wacker, J. F.


    Terrestrial planets and chondrites have noble gas platforms that are sufficiently alike, especially Ne/Ar, that they may have acquired their noble gases by similar processes. Meteorites presumably obtained their noble gases during formation in the solar nebula. Adsorption onto C - the major gas carrier in chondrites - is the likely mechanism for trapping noble gases; recent laboratory simulations support this hypothesis. The story is more complex for planets. An attractive possibility is that the planets acquired their noble gases in a late accreting veneer of chondritic material. In chondrites, noble gases correlate with C, N, H, and volatile metals; by Occam's Razor, we would expect a similar coupling in planets. Indeed, the Earth's crust and mantle contain chondritic like trace volatiles and PL group metals, respectively and the Earth's oceans resemble C chondrites in their enrichment of D (8X vs 8-10X of the galactic D/H ratio). Models have been proposed to explain some of the specific noble gas patterns in planets. These include: (1) noble gases may have been directly trapped by preplanetary material instead of arriving in a veneer; (2) for Venus, irradiation of preplanetary material, followed by diffusive loss of Ne, could explain the high concentration of AR-36; (3) the Earth and Venus may have initially had similar abundances of noble gases, but the Earth lost its share during the Moon forming event; (4) noble gases could have been captured by planetestimals, possibly leading to gravitational fractionation, particularly of Xe isotopes and (5) noble gases may have been dissolved in the hot outer portion of the Earth during contact with a primordial atmosphere.

  13. Biological effects of noble gases. (United States)

    Růzicka, J; Benes, J; Bolek, L; Markvartová, V


    Noble gases are known for their inertness. They do not react chemically with any element at normal temperature and pressure. Through that, some of them are known to be biologically active by their sedative, hypnotic and analgesic properties. Common inhalation anesthetics are characterized by some disadvantages (toxicity, decreased cardiac output, etc). Inhalation of xenon introduces anesthesia and has none of the above disadvantages, hence xenon seems to be the anesthetic gas of the future (with just one disadvantage - its cost). It is known that argon has similar anesthetic properties (under hyperbaric conditions), which is much cheaper and easily accessible. The question is if this could be used in clinical practice, in anesthesia of patients who undergo treatment in the hyperbaric chamber. Xenon was found to be organ-protective. Recent animal experiments indicated that xenon decreases infarction size after ischemic attack on brain or heart. The goal of our study is to check if hyperbaric argon has properties similar to those of xenon.

  14. Angular correlation studies in noble gases (United States)

    Coleman, P. G.


    There has been a recent revival of interest in the measurement of angular correlation of annihilation photons from the decay of positrons and positronium in gases. This revival has been stimulated by the possibility offered by the technique to shed new light on the apparently low positronium formation fraction in the heavier noble gases and to provide information on positronium quenching processes in gases such as oxygen. There is also the potential for learning about positronium slowing down in gases. This review focuses on experimental noble gas work and considers what new information has been, and may be, gained from these studies.

  15. Noble gases in crude oils from the Paris Basin, France: Implications for the origin of fluids and constraints on oil-water-gas interactions (United States)

    Pinti, Daniele L.; Marty, Bernard


    In order to investigate the potential of noble gases to trace the dynamics of oil reservoirs, we have analysed the abundance and isotopic composition of all noble gases (He, Ne, Ar, Kr, and Xe) in crude oils from the Paris Basin, France, using a new extraction and purification procedure. The main oil reservoirs are presently located in the Jurassic (Dogger) limestone and in the Triassic (Keuper) sandstone, but hydrocarbons originated from a common source rock formation located in the interbedded Liassic sequence. Despite this common origin, the abundance and isotopic ratios of the noble gases differ between the Dogger and the Keuper. The isotopic compositions of Kr and Xe are indistinguishable from that of air. 3He/ 4He ratios, higher than those predicted from radiogenic production in the sediments or in the crust, are attributed to the occurrence of mantle-derived 3He in the basin. Each sedimentary sequence is characterised by well defined and homogeneous 21Ne/ 22Ne and 40Ar/ 36Ar ratios, which average 0.0306 ± 0.0008 and 312 ± 10 for the Dogger and 0.0367 ± 0.0012 and 664 ± 30 for the Keuper, respectively. The main source of radiogenic noble gases appears to be the continental crust underlying the basin, with possible regional contributions of noble gas isotopes produced in the sediments. The helium and argon isotopic ratios of the Dogger oils are very similar to those observed in geothermal waters flowing in the Dogger aquifer throughout the basin, demonstrating that noble gases in oils derive from associated groundwaters. Oil reservoirs in the Paris Basin therefore accumulate noble gases from wide regions of the continental crust through cross-formational flow of groundwaters and subsequent partitioning into oil. This observation implies that noble gases cannot be directly used to date oils, but can provide time constraints if (1) water/oil interactions are quantified and (2) the residence time as well as the noble gas characteristics of associated

  16. Diverging effects of isotopic fractionation upon molecular diffusion of noble gases in water: mechanistic insights through ab initio molecular dynamics simulations. (United States)

    Pinto de Magalhães, Halua; Brennwald, Matthias S; Kipfer, Rolf


    Atmospheric noble gases are routinely used as natural tracers to analyze gas transfer processes in aquatic systems. Their isotopic ratios can be employed to discriminate between different physical transport mechanisms by comparison to the unfractionated atmospheric isotope composition. In many applications of aquatic systems molecular diffusion was thought to cause a mass dependent fractionation of noble gases and their isotopes according to the square root ratio of their masses. However, recent experiments focusing on isotopic fractionation within a single element challenged this broadly accepted assumption. The determined fractionation factors of Ne, Ar, Kr and Xe isotopes revealed that only Ar follows the prediction of the so-called square root relation, whereas within the Ne, Kr and Xe elements no mass-dependence was found. The reason for this unexpected divergence of Ar is not yet understood. The aim of our computational exercise is to establish the molecular-resolved mechanisms behind molecular diffusion of noble gases in water. We make the hypothesis that weak intermolecular interactions are relevant for the dynamical properties of noble gases dissolved in water. Therefore, we used ab initio molecular dynamics to explicitly account for the electronic degrees of freedom. Depending on the size and polarizability of the hydrophobic particles such as noble gases, their motion in dense and polar liquids like water is subject to different diffusive regimes: the inter-cavity hopping mechanism of small particles (He, Ne) breaks down if a critical particle size achieved. For the case of large particles (Kr, Xe), the motion through the water solvent is governed by mass-independent viscous friction leading to hydrodynamical diffusion. Finally, Ar falls in between the two diffusive regimes, where particle dispersion is propagated at the molecular collision time scale of the surrounding water molecules.

  17. Hyperpolarized noble gases as contrast agents. (United States)

    Zhou, Xin


    Hyperpolarized noble gases ((3)He and (129)Xe) can provide NMR signal enhancements of 10,000 to 100,000 times that of thermally polarized gases and have shown great potential for applications in lung magnetic resonance imaging (MRI) by greatly enhancing the sensitivity and contrast. These gases obtain a highly polarized state by employing a spin exchange optical pumping technique. In this chapter, the underlying physics of spin exchange optical pumping for production of hyperpolarized noble gases is explained and the basic components and procedures for building a polarizer are described. The storage and delivery strategies of hyperpolarized gases for in vivo imaging are discussed. Many of the problems that are likely to be encountered in practical experiments and the corresponding detailed approaches to overcome them are also discussed.

  18. Noble gases in pure lipid membranes. (United States)

    Sierra-Valdez, F J; Ruiz-Suárez, J C


    The mechanism of how a noble gas modifies the excitability of nerve cells and how such excitability can be recovered under hyperbaric pressure remains unclear. Here we present a calorimetric study where the melting point depression of pure lipid membranes induced by noble gases and its recovery with a hydrostatic pressure is addressed. A correlation is found between the electric polarizability (α) of these gases and their effect on the melting transition of the membranes. These results concur with other findings to support the idea that general anesthesia only depends on the ability of a certain atom or molecule to increase the general disorder of the membrane.

  19. Donor acceptor complexes of noble gases. (United States)

    Mück, Leonie Anna; Timoshkin, Alexey Y; von Hopffgarten, Moritz; Frenking, Gernot


    Donor-acceptor (DA) complexes of noble gases (Ng) of the general type A noble gas, a lone pair of the donor molecule and a vacant orbital of the acceptor molecule. Detailed bonding analysis of the model compounds F(3)Al-Ng-NH(3) reveals that Ng-ammonia interaction is repulsive due to Pauli repulsion. Bonding interaction between Ng and N is mostly electrostatic. In contrast, strong orbital interactions are responsible for the attractive interactions between Ng and AlF(3). Due to the repulsive interactions with the donor molecule and a sizable reorganization energy of the acceptor molecule, optimization attempts of the A noble gases. These are the first examples of the thermodynamically stable Ar and Kr compounds. Application of the push-pull cryptand ligands featuring multiple (two and three) donor-acceptor induced chemical bonds is expected to yield stable complexes with virtually any electron-rich element in the periodic table.

  20. Cold and trapped metastable noble gases

    NARCIS (Netherlands)

    Vassen, W.; Cohen-Tannoudji, C.; Leduc, M.; Boiron, D.; Westbrook, C.I.; Truscott, A.; Baldwin, K.; Birkl, G.; Cancio, P.; Trippenbach, M.


    Experimental work on cold, trapped metastable noble gases is reviewed. The aspects which distinguish work with these atoms from the large body of work on cold, trapped atoms in general is emphasized. These aspects include detection techniques and collision processes unique to metastable atoms.

  1. Noble gases as cardioprotectants - translatability and mechanism

    NARCIS (Netherlands)

    Smit, Kirsten F.; Weber, Nina C.; Hollmann, Markus W.; Preckel, Benedikt


    Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before,

  2. Noble gases as cardioprotectants - translatability and mechanism. (United States)

    Smit, Kirsten F; Weber, Nina C; Hollmann, Markus W; Preckel, Benedikt


    Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before, during and/or after ischaemia. A wide range of organs can be protected by these inert substances, in particular cardiac and neuronal tissue. In this review we summarize the data on noble gas-induced cardioprotection, focusing on the underlying protective mechanisms. We will also look at translatability of experimental data to the clinical situation. © 2014 The British Pharmacological Society.

  3. Preserving noble gases in a convecting mantle. (United States)

    Gonnermann, Helge M; Mukhopadhyay, Sujoy


    High (3)He/(4)He ratios sampled at many ocean islands are usually attributed to an essentially undegassed lower-mantle reservoir with high (3)He concentrations. A large and mostly undegassed mantle reservoir is also required to balance the Earth's (40)Ar budget, because only half of the (40)Ar produced from the radioactive decay of (40)K is accounted for by the atmosphere and upper mantle. However, geophysical and geochemical observations suggest slab subduction into the lower mantle, implying that most or all of Earth's mantle should have been processed by partial melting beneath mid-ocean ridges and hotspot volcanoes. This should have left noble gases in both the upper and the lower mantle extensively outgassed, contrary to expectations from (3)He/(4)He ratios and the Earth's (40)Ar budget. Here we suggest a simple solution: recycling and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby decreasing the rate of mantle degassing and leaving significant amounts of noble gases in the processed mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalent to approximately one lower-mantle mass over the Earth's history, high (3)He contents, high (3)He/(4)He ratios and (40)Ar concentrations high enough to satisfy the (40)Ar mass balance of the Earth can be preserved in the lower mantle. The differences in (3)He/(4)He ratios between mid-ocean-ridge basalts and ocean island basalts, as well as high concentrations of (3)He and (40)Ar in the mantle source of ocean island basalts, can be explained within the framework of different processing rates for the upper and the lower mantle. Hence, to preserve primitive noble gas signatures, we find no need for hidden reservoirs or convective isolation of the lower mantle for any length of time.

  4. Noble Gases in the Chelyabinsk Meteorites (United States)

    Haba, Makiko K.; Sumino, Hirochika; Nagao, Keisuke; Mikouchi, Takashi; Komatsu, Mutsumi; Zolensky, Michael E.


    The Chelyabinsk meteorite fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this study, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk meteorite and the thermal history of its parent asteroid.

  5. Thermodynamic Functions of Solvation of Hydrocarbons, Noble Gases, and Hard Spheres in Tetrahydrofuran-Water Mixtures. (United States)

    Sedov, I A; Magsumov, T I


    Thermodynamic solvation properties of mixtures of water with tetrahydrofuran at 298 K are studied. The Gibbs free energies and enthalpies of solvation of n-octane and toluene are determined experimentally. For molecular dynamics simulations of the binary solvent, we have modified a TraPPE-UA model for tetrahydrofuran and combined it with the SPC/E potential for water. The excess thermodynamic functions of neon, xenon, and hard spheres with two different radii are calculated using the particle insertion method. Simulated and real systems share the same characteristic trends for the thermodynamic functions. A maximum is present on dependencies of the enthalpy of solvation from the composition of solvent at 70-90 mol % water, making it higher than in both of the cosolvents. It is caused by a high enthalpy of cavity formation in the mixtures rich with water due to solvent reorganization around the cavity, which is shown by calculation of the enthalpy of solvation of hard spheres. Addition of relatively small amounts of tetrahydrofuran to water effectively suppresses the hydrophobic effect, leading to a quick increase of both the entropy and enthalpy of cavity formation and solvation of low polar molecules.

  6. Selective Growth of Noble Gases at Metal/Oxide Interface. (United States)

    Takahashi, Keisuke; Oka, Hiroshi; Ohnuki, Somei


    The locations and roles of noble gases at an oxide/metal interface in oxide dispersed metal are theoretically and experimentally investigated. Oxide dispersed metal consisting of FCC Fe and Y2Hf2O7 (Y2Ti2O7) is synthesized by mechanical alloying under a saturated Ar gas environment. Transmission electron microscopy and density functional theory observes the strain field at the interface of FCC Fe {111} and Y2Hf2O7 {111} whose physical origin emerges from surface reconstruction due to charge transfer. Noble gases are experimentally observed at the oxide (Y2Ti2O7) site and calculations reveal that the noble gases segregate the interface and grow toward the oxide site. In general, the interface is defined as the trapping site for noble gases; however, transmission electron microscopy and density functional theory found evidence which shows that noble gases grow toward the oxide, contrary to the generally held idea that the interface is the final trapping site for noble gases. Furthermore, calculations show that the inclusion of He/Ar hardens the oxide, suggesting that material fractures could begin from the noble gas bubble within the oxides. Thus, experimental and theoretical results demonstrate that noble gases grow from the interface toward the oxide and that oxides behave as a trapping site for noble gases.

  7. Exploring the Effects on Lipid Bilayer Induced by Noble Gases via Molecular Dynamics Simulations. (United States)

    Chen, Junlang; Chen, Liang; Wang, Yu; Wang, Xiaogang; Zeng, Songwei


    Noble gases seem to have no significant effect on the anesthetic targets due to their simple, spherical shape. However, xenon has strong narcotic efficacy and can be used clinically, while other noble gases cannot. The mechanism remains unclear. Here, we performed molecular dynamics simulations on phospholipid bilayers with four kinds of noble gases to elucidate the difference of their effects on the membrane. Our results showed that the sequence of effects on membrane exerted by noble gases from weak to strong was Ne, Ar, Kr and Xe, the same order as their relative narcotic potencies as well as their lipid/water partition percentages. Compared with the other three kinds of noble gases, more xenon molecules were distributed between the lipid tails and headgroups, resulting in membrane's lateral expansion and lipid tail disorder. It may contribute to xenon's strong anesthetic potency. The results are well consistent with the membrane mediated mechanism of general anesthesia.

  8. Origin of noble gases in the terrestrial planets (United States)

    Pepin, Robert O.


    Current models of the origin of noble gases in the terrestrial planets are reviewed. Primary solar system volatile sources and processes are examined along with the current data base on noble gases and its applications to evolutionary processing. Models of atmospheric evolution by hydrodynamic escape are addressed.

  9. Fullerenes and Noble Gases in the Murchison and Allende Meteorites (United States)

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.


    In this work we report the detection of fullerenes (C60 to C250) in the Murchison and Allende meteorites. By exploiting the unique ability of these molecules to trap noble gases, we have determined that fullerene is indeed a new carrier phase for noble gases in meteorites.

  10. Novel MRI Applications of Laser-Polarized Noble Gases (United States)

    Mair, R. W.; Walsworth, R. L.


    Gas-phase NMR has great potential as a probe for a variety of interesting physical and biomedical problems that are not amenable to study by water or similar liquid. However, NMR of gases was largely neglected due to the low signal obtained from the thermally-polarized gases with very low sample density. The advent of optical pumping techniques for enhancing the polarization of the noble gases 3He and 129Xe has bought new life to this field, especially in medical imaging where 3He lung inhalation imaging is approaching a clinical application. However, there are numerous applications in materials science that also benefit from the use of these gases. We review primarily non-medical applications of laser-polarized noble gases for both NMR imaging and spectroscopy, and highlight progress with examples from our laboratory including high-resolution imaging at mT applied field strength and velocity imaging of convective flow. Porous media microstucture has been probed with both thermal and laser-polarized xenon, as xenon is an ideal probe due to low surface interaction with the grains of the porous media.

  11. Sir William Ramsay and the noble gases. (United States)

    Davies, Alwyn G


    Sir William Ramsay was one of the world's leading scientists at the end of the 19th century, and in a spectacular period of research between 1894 and 1898, he discovered five new elements. These were the noble gases, helium, neon, argon, krypton, and xenon; they added a whole new group to the Periodic Table of the elements, and provided the keystone to our understanding of the electronic structure of atoms, and the way those electrons bind the atoms together into molecules. For this work he was awarded the Nobel Prize in Chemistry in 1904, the first such prize to come to a British subject. He was also a man of great charm, a good linguist, and a composer and performer of music, poetry and song. This review will trace his career, describe his character and give and account of the chemistry which led to the award of the Nobel Prize.

  12. Biomedical imaging with hyperpolarized noble gases. (United States)

    Ruppert, Kai


    Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100 000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described.

  13. Monolayer adsorption of noble gases on graphene (United States)

    Maiga, Sidi M.; Gatica, Silvina M.


    We report our results of simulations of the adsorption of noble gases (Kr, Ar, Xe) on graphene. For Kr, we consider two configurations: supported and free-standing graphene, where atoms are adsorbed only on one or two sides of the graphene. For Ar and Xe, we studied only the case of supported graphene. For the single-side adsorption, we calculated the two-dimensional gas-liquid critical temperature for each adsorbate. We determined the different phases of the monolayers and constructed the phase diagrams. We found two-dimensional incommensurate solid phases for krypton, argon and xenon, and a two-dimensional commensurate solid phase for krypton. For double side adsorption of Kr, we do not see evidence of an ordering transition driven by the interlayer forces.

  14. Noble Gases in Iddingsite from the Lafayette Meteorite: Evidence for Liquid Water on Mars in the Last Few Hundred Million Years (United States)

    Swindle, T. D.; Treiman, A. H.; Lindstrom, D. J.; Brkland, M. K.; Cohen, B. A.; Grier, J. A.; Li, B.; Olson, E. K.


    We analyzed noble gases from 18 samples of weathering products ("iddingsite") from the Lafayette meteorite. Potassium-argon ages of 12 samples range from near zero to 670 +/- 91 Ma. These ages confirm the martian origin of the iddingsite, but it is not clear whether any or all of the ages represent iddingsite formation as opposed to later alteration or incorporation of martian atmospheric Ar-40. In any case, because iddingsite formation requires liquid water, this data requires the presence of liquid water near the surface of Mars at least as recently as 1300 Ma ago, and probably as recently as 650 Ma ago. Krypton and Xe analysis of a single 34 microg sample indicates the presence of fractionated martian atmosphere within the iddingsite. This also confirms the martian origin of the iddingsite. The mechanism of incorporation could either be through interaction with liquid water during iddingsite formation or a result of shock implantation of adsorbed atmospheric gas.

  15. [A possible molecular mechanism of the narcotic action of noble gases]. (United States)

    Dovgusha, V V; Fok, M V; Zaritskaia, G A


    A molecular mechanism of the narcotic action of noble gases is suggested, which is based on the fact that noble gas atoms change the orientation of water molecules absorbed on the surface of axon membrane. The resulting change in the transmembrane potential deteriorates the propagation of nerve pulse.

  16. The Noble Gases in A-Level Chemistry. (United States)

    Marchant, G. W.


    Suggests two methods of developing the study of the noble gases: first, the discovery of the elements and recent discovery of xenon show the human face of chemistry (historical development); second, the properties of noble gas compounds (particularly xenon) can be used to test the framework of conventional chemistry. (Author/JM)

  17. Phase Q - A carrier for subsolar noble gases


    Busemann, H.; Baur, H.; R. Wieler


    We discuss noble gases in the E-chondrite St. Mark's indicating that the subsolar component does not exclusively reside in enstatite. Element and isotope abundances including He are presented. Fractionation probably took place prior to incorporation.\\ud

  18. Noble gases recycled into the mantle through cold subduction zones (United States)

    Smye, Andrew J.; Jackson, Colin R. M.; Konrad-Schmolke, Matthias; Hesse, Marc A.; Parman, Steve W.; Shuster, David L.; Ballentine, Chris J.


    Subduction of hydrous and carbonated oceanic lithosphere replenishes the mantle volatile inventory. Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H2O and CO2. Here, we use noble gases as tracers for deep volatile cycling. Specifically, we construct and apply a kinetic model to estimate the effect of subduction zone metamorphism on the elemental composition of noble gases in amphibole - a common constituent of altered oceanic crust. We show that progressive dehydration of the slab leads to the extraction of noble gases, linking noble gas recycling to H2O. Noble gases are strongly fractionated within hot subduction zones, whereas minimal fractionation occurs along colder subduction geotherms. In the context of our modelling, this implies that the mantle heavy noble gas inventory is dominated by the injection of noble gases through cold subduction zones. For cold subduction zones, we estimate a present-day bulk recycling efficiency, past the depth of amphibole breakdown, of 5-35% and 60-80% for 36Ar and H2O bound within oceanic crust, respectively. Given that hotter subduction dominates over geologic history, this result highlights the importance of cooler subduction zones in regassing the mantle and in affecting the modern volatile budget of Earth's interior.

  19. The diverse biological properties of the chemically inert noble gases. (United States)

    Winkler, David A; Thornton, Aaron; Farjot, Géraldine; Katz, Ira


    The noble gases represent an intriguing scientific paradox. They are extremely inert chemically but display a remarkable spectrum of clinically useful biological properties. Despite a relative paucity of knowledge of their mechanisms of action, some of the noble gases have been used successfully in the clinic. Studies with xenon have suggested that the noble gases as a class may exhibit valuable biological properties such as anaesthesia; amelioration of ischemic damage; tissue protection prior to transplantation; analgesic properties; and a potentially wide range of other clinically useful effects. Xenon has been shown to be safe in humans, and has useful pharmacokinetic properties such as rapid onset, fast wash out etc. The main limitations in wider use are that: many of the fundamental biochemical studies are still lacking; the lighter noble gases are likely to manifest their properties only under hyperbaric conditions, impractical in surgery; and administration of xenon using convectional gaseous anaesthesia equipment is inefficient, making its use very expensive. There is nonetheless a significant body of published literature on the biochemical, pharmacological, and clinical properties of noble gases but no comprehensive reviews exist that summarize their properties and the existing knowledge of their models of action at the molecular (atomic) level. This review provides such an up-to-date summary of the extensive, useful biological properties of noble gases as drugs and prospects for wider application of these atoms. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  20. Photosensitive dopants for liquid noble gases (United States)

    Anderson, David F.


    In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

  1. Diffusive separation of noble gases and noble gas abundance patterns in sedimentary rocks

    Energy Technology Data Exchange (ETDEWEB)

    Torgersen, T.; Kennedy, B.M.; van Soest, M.C.


    The mechanisms responsible for noble gas concentrations, abundance patterns, and strong retentivity in sedimentary lithologies remain poorly explained. Diffusion-controlled fractionation of noble gases is modeled and examined as an explanation for the absolute and relative abundances of noble gases observed in sediments. Since the physical properties of the noble gases are strong functions of atomic mass, the individual diffusion coefficients, adsorption coefficients and atomic radii combine to impede heavy noble gas (Xe) diffusion relative to light noble gas (Ne) diffusion. Filling of lithic grains/half-spaces by diffusive processes thus produces Ne enrichments in the early and middle stages of the filling process with F(Ne) values similar to that observed in volcanic glasses. Emptying lithic grains/half-spaces produces a Xe-enriched residual in the late (but not final) stages of the process producing F(Xe) values similar to that observed in shales. 'Exotic but unexceptional' shales that exhibit both F(Ne) and F(Xe) enrichments can be produced by incomplete emptying followed by incomplete filling. This mechanism is consistent with literature reported noble gas abundance patterns but may still require a separate mechanism for strong retention. A system of labyrinths-with-constrictions and/or C-, Si-nanotubes when combined with simple adsorption can result in stronger diffusive separation and non-steady-state enrichments that persist for longer times. Enhanced adsorption to multiple C atoms inside C-nanotubes as well as dangling functional groups closing the ends of nanotubes can provide potential mechanisms for 'strong retention'. We need new methods of examining noble gases in rocks to determine the role and function of angstrom-scale structures in both the diffusive enrichment process and the 'strong retention' process for noble gas abundances in terrestrial rocks.

  2. van der Waals radii of noble gases. (United States)

    Vogt, Jürgen; Alvarez, Santiago


    Consistent van der Waals radii are deduced for Ne-Xe, based on the noble gas···oxygen intermolecular distances found in gas phase structures. The set of radii proposed is shown to provide van der Waals distances for a wide variety of noble gas···element atom pairs that represent properly the distribution of distances both in the gas phase and in the solid state. Moreover, these radii show a smooth periodic trend down the group which is parallel to that shown by the halogens.

  3. [Neuroprotection by noble gases: New developments and insights]. (United States)

    Fahlenkamp, A V; Rossaint, R; Coburn, M


    Noble gases are chemically inert elements, some of which exert biological activity. Experimental neuroprotection in particular has been widely shown for xenon, argon and helium. The underlying mechanisms of action are not yet fully understood. Besides an interference with neuronal ion-gated channels and cellular signaling pathways as well as anti-apoptotic effects, the modulation of neuroinflammation seems to play a crucial role. This review presents the current knowledge on neuroprotection by noble gases with a focus on interactions with the neuronal-glial network and neuroinflammation and the perspectives on clinical applications.

  4. Fullerenes: A New Carrier Phase for Noble Gases in Meteorites (United States)

    Becker, Luann


    The major focus of our research effort has been to measure the noble gases encapsulated within fullerenes, a new carbon carrier phase and compare it to the myriad of components found in the bulk meteorite acid residues. We have concentrated on the carbonaceous chondrites (Allende, Murchison and Tagish Lake) since they have abundant noble gases, typically with a planetary signature that dominates the stepped-release of the meteorite bulk acid residue. They also contain an extractable fullerene component that can be isolated and purified from the same bulk material.

  5. Dynamics of a geothermal field traced by noble gases: Cerro Prieto, Mexico (United States)

    Mazor, E.; Truesdell, A.H.


    Noble gases have been measured mass spectrometrically in samples collected during 1977 from producing wells at Cerro Prieto. Positive correlations between concentrations of radiogenic (He and 40Ar) and atmospheric noble gases (Ne, Ar and Kr) suggest the following dynamic model: the geothermal fluids originated from meteoric water that penetrated to more than 2500 m depth (below the level of first boiling) and mixed with radiogenic He and 40Ar formed in the aquifer rocks. Subsequently, small amounts of steam were lost by a Raleigh process (0 - 30%) and mixing with shallow cold water occurred (0 - 30%). Noble gases are sensitive tracers of boiling in the initial stages of 0 - 3% steam separation and complement other tracers, such as C1 or temperature, which are effective only beyond this range. ?? 1984.

  6. Dynamics of a geothermal field traced by noble gases: Cerro Prieto, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Mazor, E. (Weizmann Inst. of Science, Rehovot, Israel); Truesdell, A.H.


    Noble gases have been measured mass spectrometrically in samples collected during 1977 from producing wells at Cerro Prieto. Positive correlations between concentrations of radiogenic (He, /sup 40/Ar) and atmospheric noble gases (Ne, Ar, and Kr) suggest the following dynamic model: the geothermal fluids originated from meteoric water penetrated to more than 2500 m depth (below the level of first boiling) and mixed with radiogenic helium and argon-40 formed in the aquifer rocks. Subsequently, small amounts of steam were lost by a Raleigh process (0 to 3%) and mixing with shallow cold water occurred (0 to 30%). Noble gases are sensitive tracers of boiling in the initial stages of 0 to 3% steam separation and complement other tracers, such as Cl or temperature, which are effective only beyond this range.

  7. The trapped heavy noble gases in recently found Martian meteorites


    Busemann, H.; Eugster, O.


    The composition of the trapped Ar, Kr, and Xe in the Martian meteorites Los Angeles, Say Al Uhaymir 005/008, and 094 is discussed and found to be consistent with a mixture of Martian mantle and atmosphere noble gases and terrestrial contamination.

  8. Noble Gases in the Hamlet Meteorite (LL4) (United States)

    Amari, S.; Sabe, Y.; Shiraishi, T.; Matsuda, J.


    We analyzed noble gases in a bulk sample and an HF-HCl residue of Hamlet (LL4). The Xe composition of the residue shows that no diamond is contained in the residue. The 20Ne/22Ne ratio of Hamlet Ne-Q has been determined to be 11.0 ± 0.5.

  9. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases (United States)

    Gross, Kenneth C.; Markun, Francis; Zawadzki, Mary T.


    An apparatus and method for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir.

  10. A portable membrane contactor sampler for analysis of noble gases in groundwater. (United States)

    Matsumoto, Takuya; Han, Liang-Feng; Jaklitsch, Manfred; Aggarwal, Pradeep K


    To enable a wider use of dissolved noble gas concentrations and isotope ratios in groundwater studies, we have developed an efficient and portable sampling device using a commercially available membrane contactor. The device separates dissolved gases from a stream of water and collects them in a small copper tube (6 mm in diameter and 100 mm in length with two pinch-off clamps) for noble gas analysis by mass spectrometry. We have examined the performance of the sampler using a tank of homogeneous water prepared in the laboratory and by field testing. We find that our sampling device can extract heavier noble gases (Ar, Kr, and Xe) more efficiently than the lighter ones (He and Ne). An extraction time of about 60 min at a flow rate of 3 L/min is sufficient for all noble gases extracted in the sampler to attain equilibrium with the dissolved phase. The extracted gas sample did not indicate fractionation of helium ((3) He/(4) He) isotopes or other noble gas isotopes. Field performance of the sampling device was tested using a groundwater well in Vienna and results were in excellent agreement with those obtained from the conventional copper tube sampling method. © 2012, National Ground Water Association.

  11. Noble gases as cardioprotectants – translatability and mechanism (United States)

    Smit, Kirsten F; Weber, Nina C; Hollmann, Markus W; Preckel, Benedikt


    Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before, during and/or after ischaemia. A wide range of organs can be protected by these inert substances, in particular cardiac and neuronal tissue. In this review we summarize the data on noble gas-induced cardioprotection, focusing on the underlying protective mechanisms. We will also look at translatability of experimental data to the clinical situation. PMID:25363501

  12. Using noble gases to investigate mountain-front recharge (United States)

    Manning, A.H.; Solomon, D.K.


    Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central importance in source protection planning for basin-fill aquifers and in some water rights disputes, yet existing estimates carry large uncertainties. Stable isotope ratios can indicate the magnitude of mountain-front recharge relative to other components, but are generally incapable of distinguishing subsurface inflow from stream seepage. Noble gases provide an effective tool for determining the relative significance of subsurface inflow, specifically. Dissolved noble gas concentrations allow for the determination of recharge temperature, which is correlated with recharge elevation. The nature of this correlation cannot be assumed, however, and must be derived for the study area. The method is applied to the Salt Lake Valley Principal Aquifer in northern Utah to demonstrate its utility. Samples from 16 springs and mine tunnels in the adjacent Wasatch Mountains indicate that recharge temperature decreases with elevation at about the same rate as the mean annual air temperature, but is on average about 2??C cooler. Samples from 27 valley production wells yield recharge elevations ranging from the valley elevation (about 1500 m) to mid-mountain elevation (about 2500 m). Only six of the wells have recharge elevations less than 1800 m. Recharge elevations consistently greater than 2000 m in the southeastern part of the basin indicate that subsurface inflow constitutes most of the total recharge in this area. ?? 2003 Published by Elsevier Science B.V.

  13. Fullerenes: An extraterrestrial carbon carrier phase for noble gases (United States)

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.


    In this work, we report on the discovery of naturally occurring fullerenes (C60 to C400) in the Allende and Murchison meteorites and some sediment samples from the 65 million-year-old Cretaceous/Tertiary boundary layer (KTB). Unlike the other pure forms of carbon (diamond and graphite), fullerenes are extractable in an organic solvent (e.g., toluene or 1,2,4-trichlorobenzene). The recognition of this unique property led to the detection and isolation of the higher fullerenes in the Kratschmer/Huffmann arc evaporated graphite soot and in the carbon material in the meteorite and impact deposits. By further exploiting the unique ability of the fullerene cage structure to encapsulate and retain noble gases, we have determined that both the Allende and Murchison fullerenes and the KTB fullerenes contain trapped noble gases with ratios that can only be described as extraterrestrial in origin. PMID:10725367

  14. Howardite Noble Gases as Indicators of Asteroid Surface Processing (United States)

    Cartwright, J. A.; Mittlefehldt, D. W.; Herrin, J. S.; Ott, U.


    The HED (Howardite, Eucrite and Diogenite) group meteorites likely or iginate from the Asteroid 4 Vesta - one of two asteroid targets of NA SA's Dawn mission. Whilst Howardites are polymict breccias of eucriti c and diogenitic material that often contain "regolithic" petrologica l features, neither their exact regolithic nature nor their formation processes are well defined. As the Solar Wind (SW) noble gas compon ent is implanted onto surfaces of solar system bodies, noble gas anal yses of Howardites provides a key indicator of regolithic origin. In addition to SW, previous work by suggested that restricted Ni (300-12 00 micro g/g) and Al2O3 (8-9 wt%) contents may indicate an ancient we ll-mixed regolith. Our research combines petrological, compositional and noble gas analyses to help improve understanding of asteroid reg olith formation processes, which will play an intergral part in the i nterpretation of Dawn mission data. Following compositional and petrological analyses, we developed a regolith grading scheme for our sampl e set of 30 Howardites and polymict Eucrites. In order to test the r egolith indicators suggested by, our 8 selected samples exhibited a r ange of Ni, Al2O3 contents and regolithic grades. Noble gas analyses were performed using furnace stepheating on our MAP 215-50 noble gas mass spectrometer. Of our 8 howardites, only 3 showed evidence of SW noble gases (e.g approaching Ne-20/Ne-22 approximately equals 13.75, Ne-21/Ne-22 approximately equals 0.033). As these samples display low regolithic grades and a range of Ni and Al2O3 contents, so far we are unable to find any correlation between these indicators and "regolit hic" origin. These results have a number of implications for both Ho wardite and Vesta formation, and may suggest complex surface stratigr aphies and surface-gardening processes.

  15. Trapping of noble gases in proton-irradiated silicate smokes (United States)

    Nichols, R. H., Jr.; Nuth, J. A., III; Hohenberg, C. M.; Olinger, C. T.; Moore, M. H.


    We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.

  16. GEM operation in pure noble gases and the avalanche confinement

    CERN Document Server

    Buzulutskov, A F; Bressan, A; Mauro, A D; Ropelewski, Leszek; Sauli, Fabio; Biagi, S F


    We study the operation of the Gas Electron Multiplier (GEM) in pure Ar and almost pure Xe. Rather high gas gains obtained in pure Ar, of the order of 1000, are explained by the effect of the avalanche confinement to a GEM micro-hole. Applications to the development of non-ageing sealed photon detector filled with pure noble gases are discussed. In particular, it is shown that the photoelectron collection efficiency deteriorated in pure Ar due to electron backscattering, can be recovered by operation at a higher electric field.

  17. Effective Giromagnetic Ratios in Artifical Nuclear Magnetization Pumping of the Noble Gases Mix

    Directory of Open Access Journals (Sweden)

    Popov E.N.


    Full Text Available Dynamic of the nuclear magnetization of the two noble gases mix was studied in this research. Nuclear magnetization pumped along the induction of external magnetic field. Vector of nuclear magnetization is given a tilt by the week rotational magnetic field, which makes NMR for noble gases. Interaction between the nuclear magnetic moments of the different noble gases adducted to shifts at the frequency of nuclear moments precession in external magnetic field. Effective gyromagnetic ratios of the nuclear of noble gases is defined and it different from the tabulated value. There is theoretical calculation of effective gyromagnetic ratios in this research.

  18. Noble gases in the howardites Bholghati and Kapoeta (United States)

    Swindle, T. D.; Hohenberg, C. M.; Nickols, R. H.; Olinger, C.; Garrison, D. H.; Goswami, J. N.


    Analyses of noble gases in whole rock samples of the howardites Bholghati and Kapoeta and grain-size separates of Kapoeta yield evidence for excesses of the Xe isotopes Xe-129 , Xe-131, Xe-132, Xe-134, and Xe-136 in a low-temperture component, similar to lunar excess fission Xe. Such a component may be able to provide chronometric information if the relative abundances of radioactive progenitors (I-129, Pu-244, and U-238) can be determined, but the isotopic spectra obtained are not sufficiently precise to do so. Eucritic clast BH-5 in Bholghati contains Xe produced in situ by the decay of Pu-244. Calculated fission Xe retention ages are 30-70 Ma after the formation of the solar system, consistent with the apparent presence of Sm-146 decay products. Both the clast and the matrix of Bholghati have K-Ar ages of about 2 Ga, suggesting a common thermal event at least that recently.

  19. Heavy noble gases in solar wind delivered by Genesis mission. (United States)

    Meshik, Alex; Hohenberg, Charles; Pravdivtseva, Olga; Burnett, Donald


    One of the major goals of the Genesis Mission was to refine our knowledge of the isotopic composition of the heavy noble gases in solar wind and, by inference, the Sun, which represents the initial composition of the solar system. This has now been achieved with permil precision: (36)Ar/(38)Ar = 5.5005 ± 0.0040, (86)Kr/(84)Kr = .3012 ± .0004, (83)Kr/(84)Kr = .2034 ± .0002, (82)Kr/(84)Kr = .2054 ± .0002, (80)Kr/(84)Kr = .0412 ± .0002, (78)Kr/(84)Kr = .00642 ± .00005, (136)Xe/(132)Xe = .3001 ± .0006, (134)Xe/(132)Xe = .3691 ± .0007, (131)Xe/(132)Xe = .8256 ± .0012, (130)Xe/(132)Xe = .1650 ± .0004, (129)Xe/(132)Xe = 1.0405 ± .0010, (128)Xe/(132)Xe = .0842 ± .0003, (126)Xe/(132)Xe = .00416 ± .00009, and (124)Xe/(132)Xe = .00491 ± .00007 (error-weighted averages of all published data). The Kr and Xe ratios measured in the Genesis solar wind collectors generally agree with the less precise values obtained from lunar soils and breccias, which have accumulated solar wind over hundreds of millions of years, suggesting little if any temporal variability of the isotopic composition of solar wind krypton and xenon. The higher precision for the initial composition of the heavy noble gases in the solar system allows (1) to confirm that, exept (136)Xe and (134)Xe, the mathematically derived U-Xe is equivalent to Solar Wind Xe and (2) to provide an opportunity for better understanding the relationship between the starting composition and Xe-Q (and Q-Kr), the dominant current "planetary" component, and its host, the mysterious phase-Q.

  20. Noble gases solubility models of hydrocarbon charge mechanism in the Sleipner Vest gas field (United States)

    Barry, P. H.; Lawson, M.; Meurer, W. P.; Warr, O.; Mabry, J. C.; Byrne, D. J.; Ballentine, C. J.


    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways and mechanisms, as well as reservoir storage conditions. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. Here, we present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner Vest gases are generated from primary cracking of kerogen and the thermal cracking of oil. Gas was emplaced into the Sleipner Vest from the south and subsequently migrated to the east, filling and spilling into the Sleipner Ost fields. Gases principally consist of hydrocarbons (83-93%), CO2 (5.4-15.3%) and N2 (0.6-0.9%), as well as trace concentrations of noble gases. Helium isotopes (3He/4He) are predominantly radiogenic and range from 0.065 to 0.116 RA; reported relative to air (RA = 1.4 × 10-6; Clarke et al., 1976; Sano et al., 1988), showing predominantly (>98%) crustal contributions, consistent with Ne (20Ne/22Ne from 9.70 to 9.91; 21Ne/22Ne from 0.0290 to 0.0344) and Ar isotopes (40Ar/36Ar from 315 to 489). Air-derived noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe) are introduced into the hydrocarbon system by direct exchange with air-saturated water (ASW). The distribution of air-derived noble gas species are controlled by phase partitioning processes; in that they preferentially partition into the gas (i.e., methane) phase, due to their low solubilities in fluids. Therefore, the extent of exchange between hydrocarbon phases and formation waters - that have previously equilibrated with the atmosphere - can be determined by investigating air-derived noble gas species. We utilize both elemental ratios to address process (i.e., open vs. closed system) and concentrations to quantify the extent of hydrocarbon-water

  1. Delayed Higher-Order Optical Nonlinearities in Noble Gases (United States)

    Tarazkar, Maryam; Romanov, Dmitri; Levis, Robert


    The role of higher-order Kerr effect (HOKE) in femtosecond laser filamentation is currently at the center of a controversy, as alleged crossover from positive to negative nonlinear refractive index at higher intensities was proposed to cause filament stabilization. Experimental evidence of HOKE crossover or lack thereof is being hotly debated. Motivated by this debate, we report the frequency-dependent nonlinear refractive index coefficients n2 and n4 for a series of atmospheric-pressure noble gases: helium, neon, argon, krypton, and xenon. The corresponding atomic hyperpolarizability coefficients are obtained via auxiliary static electric field approach developed on the basis of ab initio calculations implemented in Dalton program and performed at the CCSD level of theory with t-Aug-cc-PV5Z basis set. The n4 index is obtained using the relations between the degenerate six-wave mixing coefficient and some other frequency-dependent second hyperpolarizability coefficients, which can be calculated on the basis of n2via the auxiliary field approach. For all the investigated gases, the n4 indices are found to be positive over the wavelength range 300 nm-1500 nm. This result runs counter to the HOKE crossover hypothesis. The calculated n4 indices demonstrate considerable temporal dispersion, which progressively increases from helium to xenon. This feature implies delayed nonlinearity and calls for modifications in current theoretical models of filamentation process. We gratefully acknowledge financial support through AFOSR MURI Grant No. FA9550-10-1-0561.

  2. Optimizing Noble Gas-Water Interactions via Monte Carlo Simulations. (United States)

    Warr, Oliver; Ballentine, Chris J; Mu, Junju; Masters, Andrew


    In this work we present optimized noble gas-water Lennard-Jones 6-12 pair potentials for each noble gas. Given the significantly different atomic nature of water and the noble gases, the standard Lorentz-Berthelot mixing rules produce inaccurate unlike molecular interactions between these two species. Consequently, we find simulated Henry's coefficients deviate significantly from their experimental counterparts for the investigated thermodynamic range (293-353 K at 1 and 10 atm), due to a poor unlike potential well term (εij). Where εij is too high or low, so too is the strength of the resultant noble gas-water interaction. This observed inadequacy in using the Lorentz-Berthelot mixing rules is countered in this work by scaling εij for helium, neon, argon, and krypton by factors of 0.91, 0.8, 1.1, and 1.05, respectively, to reach a much improved agreement with experimental Henry's coefficients. Due to the highly sensitive nature of the xenon εij term, coupled with the reasonable agreement of the initial values, no scaling factor is applied for this noble gas. These resulting optimized pair potentials also accurately predict partitioning within a CO2-H2O binary phase system as well as diffusion coefficients in ambient water. This further supports the quality of these interaction potentials. Consequently, they can now form a well-grounded basis for the future molecular modeling of multiphase geological systems.

  3. The desorption behaviour of implanted noble gases at low energy on silicon surfaces

    NARCIS (Netherlands)

    Holtslag, A.H.M.; van Silfhout, Arend


    Under UHV conditions, clean crystalline Si(111) surfaces have been bombarded mass-selectively at room temperature with noble gas ions, Ne+, Ar+, Kr+, at normal incidence. By means of stepwise heating up to 1050 K the activation energies and desorbed doses of the noble gases have been straight

  4. Metal-organic frameworks for adsorption and separation of noble gases (United States)

    Allendorf, Mark D.; Greathouse, Jeffery A.; Staiger, Chad


    A method including exposing a gas mixture comprising a noble gas to a metal organic framework (MOF), including an organic electron donor and an adsorbent bed operable to adsorb a noble gas from a mixture of gases, the adsorbent bed including a metal organic framework (MOF) including an organic electron donor.

  5. Noble gases in 'phase Q' - Closed-system etching of an Allende residue (United States)

    Wieler, Rainer; Baur, Heinrich; Signer, Peter; Anders, Edward; Lewis, Roy S.


    Results are presented from an analysis, in nearly pure form, of noble gases from the 'phase-Q' in an HF/HCl residue of the Allende C3V meteorite, using the closed-system stepped etching technique developed by Wieler et al. (1986) and Benkert et al. (1988) to extract noble gases from the residue. The results yield precise values of element and isotope abundances of all five noble gases in phase-Q, which is the major carrier of the planetary gases in carbonaceous chondrites. It was found that Ne-Q and Xe-Q in Allende are very similar to trapped gases in ureilites and in oxidizable carriers in several classes of ordinary chandrites, indicating that Q-gases are present in the formation locations of all these meteorites.

  6. Solar wind record in the lunar regolith - Nitrogen and noble gases (United States)

    Frick, Urs; Becker, Richard H.; Pepin, Robert O.


    The measured elemental and isotopic abundances of noble gases and nitrogen have been measured in five different samples of lunar regolith material. It was found noble gases liberated by chemical attack on grain surfaces from two of the samples were solar. The Ne-20/Ne-22 ratio in the two grain surface reservoir is 13.5-13.6, compared to the average value of 13.7 + or - 0.3 measured in the Apollo solar wind collection foils (Gochsler and Geiss, 1977). It is suggested that the noble gases in grain interiors have suffered severe mass fractionation. The surface-sited N/Ar in an ilmenite sample exceeds the predicted solar ratio by more than a factor of 10. It is concluded that the solar system abundances of Cameron (1982) describe the elemental composition of the noble gases in the solar wind very well.

  7. Shock wave fractionated noble gases in the early solar system (United States)

    Ustinova, G. K.


    Many processes in the active star-forming regions are accompanied by strong shock waves, in acceleration by which the nuclear-active particles form the power-law energy spectrum of high rigidity: F(> E0) ˜ Eγ , with the spectral index γ ≤ 1.5-2. It must affect the production rates of spallogenic components of the isotopes, whose excitation functions depend on the shape of the energy spectrum of radiation. Thus, the isotopic signatures formed in the conditions of the strong shock wave propagation must be different from those formed in the calm environment. The early solar system incorporated all the presumed processes of the starforming stage, so that its matter had to conserve such isotopic anomalies. In previous works [1] the shock wave effects in generation of extinct radionu-clides and light elements Li, Be and B were considered. In the report some results for their evidence in the noble gas signatures are presented. Modelling the Kr isotope generation in spallation of Rb, Sr, Y and Zr with the nuclear-active particles, the energy spectrum of which was variable in the range of γ= 1.1-6.0, shows the different pace of growth of abundances of the dif-ferent Kr isotopes with decreasing . It leads to the quite diverse behaviour of the various Kr isotope ratios: the 78,80 Kr/83 Kr ratios increase, and the 82,84,86 Kr/83 Kr ratios decrease for the smaller γ. According to such criteria, for instance, the isotopically heavier SEP-Kr in the lunar ilmenites was pro-duced with the accelerated particles of the more rigid energy spectrum (γ ˜ 2) in comparison with the SW-Kr. Another important feature of the shock wave acceleration of particles is the enrichment of their specrtum with heavier ions in proportion to A/Z. Clearly, the shock wave fractionation of the noble gases, favouring the heavier isotopes, had to be inevitable. Such a fractionation depends on timing episodes of shock wave acceleration: after the n-th act of the ion acceleration their fractionation is

  8. CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.


    Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0noble gasisotopes caused by diffusion in ambient liquid water.

  9. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives. (United States)

    Grandinetti, Felice


    This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.

  10. Effect of noble gases on oxygen and glucose deprived injury in human tubular kidney cells. (United States)

    Rizvi, Maleeha; Jawad, Noorulhuda; Li, Yuantao; Vizcaychipi, Marcela P; Maze, Mervyn; Ma, Daqing


    The noble gas xenon has been shown to be protective in preconditioning settings against renal ischemic injury. The aims of this study were to determine the protective effects of the other noble gases, helium, neon, argon, krypton and xenon, on human tubular kidney HK2 cells in vitro. Cultured human renal tubular cells (HK2) were exposed to noble gas preconditioning (75% noble gas; 20% O(2); 5% CO(2)) for three hours or mock preconditioning. Twenty-four hours after gas exposure, cell injury was provoked with oxygen-glucose deprived (OGD) culture medium for three hours. Cell viability was assessed 24 h post-OGD by a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Other cohorts of cultured cells were incubated in the absence of OGD in 75% noble gas, 20% O(2) and 5% CO(2) and cellular signals phospho-Akt (p-Akt), hypoxia-inducible factor-1alpha (HIF-1alpha) and Bcl-2 were assessed by Western blotting. OGD caused a reduction in cell viability to 0.382 +/- 0.1 from 1.0 +/- 0.15 at control (P 0.05). Helium by comparison significantly enhanced cell injury (0.191 +/- 0.05; P noble gases did not modify protein expression. These results suggest that unlike other noble gases, preconditioning with the anesthetic noble gas xenon may have a role in protection against renal ischemic injury.

  11. Modelling of noble anaesthetic gases and high hydrostatic pressure effects in lipid bilayers. (United States)

    Moskovitz, Yevgeny; Yang, Hui


    Our objective was to study molecular processes that might be responsible for inert gas narcosis and high-pressure nervous syndrome. The classical molecular dynamics trajectories (200 ns) of dioleoylphosphatidylcholine (DOPC) bilayers simulated by the Berger force field were evaluated for water and the atomic distribution of noble gases around DOPC molecules in the pressure range of 1-1000 bar and at a temperature of 310 K. Xenon and argon have been tested as model gases for general anaesthetics, and neon has been investigated for distortions that are potentially responsible for neurological tremors in hyperbaric conditions. The analysis of stacked radial pair distribution functions of DOPC headgroup atoms revealed the explicit solvation potential of the gas molecules, which correlates with their dimensions. The orientational dynamics of water molecules at the biomolecular interface should be considered as an influential factor, while excessive solvation effects appearing in the lumen of membrane-embedded ion channels could be a possible cause of inert gas narcosis. All the noble gases tested exhibit similar order parameter patterns for both DOPC acyl chains, which are opposite of the patterns found for the order parameter curve at high hydrostatic pressures in intact bilayers. This finding supports the 'critical volume' hypothesis of anaesthesia pressure reversal. The irregular lipid headgroup-water boundary observed in DOPC bilayers saturated with neon in the pressure range of 1-100 bar could be associated with the possible manifestation of neurological tremors at the atomic scale. The non-immobiliser neon also demonstrated the highest momentum impact on the normal component of the DOPC diffusion coefficient representing the monolayer undulation rate, which indicates that enhanced diffusivity rather than atomic size is the key factor.

  12. The noble gases: how their electronegativity and hardness determines their chemistry. (United States)

    Furtado, Jonathan; De Proft, Frank; Geerlings, Paul


    The establishment of an internally consistent scale of noble gas electronegativities is a long-standing problem. In the present study, the problem is attacked via the Mulliken definition, which in recent years gained widespread use to its natural appearance in the context of conceptual density functional theory. Basic ingredients of this scale are the electron affinity and the ionization potential. Whereas the latter can be computed routinely, the instability of the anion makes the judicious choice of computational technique for evaluating electron affinities much more tricky. We opted for Puiatti's approach, extrapolating the energy of high ε solvent stabilized anions to the ε = 1 (gas phase) case. The results give negative electron affinity values, monotonically increasing (except for helium which is an outlier in most of the story) to almost zero at eka-radon in agreement with high level calculations. The stability of the B3LYP results is successfully tested both via improving the level of theory (CCSD(T)) and expanding the basis set. Combined with the ionization energies (in good agreement with experiment), an electronegativity scale is obtained displaying (1) a monotonic decrease of χ when going down the periodic table, (2) top values not for the noble gases but for the halogens, as opposed to most (extrapolation) procedures of existing scales, invariably placing the noble gases on top, and (3) noble gases having electronegativities close to the chalcogens. In the accompanying hardness scale (hardly, if ever, discussed in the literature) the noble gases turn out to be by far the farthest the hardest elements, again with a continuous decrease with increasing Z. Combining χ value of the halogens and the noble gases the Ng(δ+)F(δ-) bond polarity emerging from ab initio calculations naturally emerges. In conclusion, the chemistry of the noble gases is for a large part determined by their extreme hardness, equivalent to a high resistance to change in its

  13. An Atomistic Study of the Incorporation and Diffusion of Noble Gases in Silicate Minerals (United States)

    Pinilla, C.; Valencia, K.; Martinez-Mendoza, C.; Allan, N.


    Trace elements are widely used to unravel magmatic processes and constrain the chemical differentiation of the Earth. Central to this enterprise is understanding the controls on trace element fractionation between solid and liquid phases and thus the energetics of incorporating trace elements into crystals. In this contribution we focus on the incorporation of noble gases into crystals, with implications for the degassing processes in the Earth and the atmosphere. We use both ab-initio and classical calculations using interatomic potentials to study the uptake of the noble gases He, Ne and Ar into solid silicates. We calculate atomic defect energies of incorporation both at vacancies and at interstitial positions in solid forsterite. We use these energies to estimate the total uptake of the noble gases bulk into the crystal as a function of temperature. Such concentrations are found to be very low (10-3 and 10-10 ppm) for He up to Ar respectively with the noble gases incorporated predicted to be more favorable at intrinsic vacancies of Si or Mg or at interstitials sites. We also look at the diffusion of these minerals within the lattice and estimate activation energies for such processes. Our results support the hypothesis that noble gases have very low solubilities in bulk solid minerals. Other mechanisms such as adsorption at internal and external interfaces, voids and grain boundaries that can play a mayor role in their storage are also briefly discussed.

  14. Impact of artificial recharge on dissolved noble gases in groundwater in California. (United States)

    Cey, Bradley D; Hudson, G Bryant; Moran, Jean E; Scanlon, Bridget R


    Dissolved noble gas concentrations in groundwater can provide valuable information on recharge temperatures and enable 3H-3He age-dating with the use of physically based interpretive models. This study presents a large (905 samples) data set of dissolved noble gas concentrations from drinking water supply wells throughout California, representing a range of physiographic, climatic, and water management conditions. Three common interpretive models (unfractionated air, UA; partial re-equilibration, PR; and closed system equilibrium, CE) produce systematically different recharge temperatures or ages; however, the ability of the different models to fit measured data within measurement uncertainty indicates that goodness-of-fit is not a robust indicator for model appropriateness. Therefore caution is necessary when interpreting model results. Samples from multiple locations contained significantly higher Ne and excess air concentrations than reported in the literature, with maximum excess air tending toward 0.05 cm3 STP g(-1) (deltaNe approximately 400%). Artificial recharge is the most plausible cause of the high excess air concentrations. The ability of artificial recharge to dissolve greater amounts of atmospheric gases has important implications for oxidation-reduction dependent chemical reactions. Measured gas concentration ratios suggest that diffusive degassing may have occurred. Understanding the physical processes controlling gas dissolution during groundwater recharge is critical for optimal management of artificial recharge and for predicting changes in water quality that can occur following artificial recharge.

  15. Method and apparatus for measuring purity of noble gases (United States)

    Austin, Robert


    A device for detecting impurities in a noble gas includes a detection chamber and a source of pulsed ultraviolet light. The pulse of the ultraviolet light is transferred into the detection chamber and onto a photocathode, thereby emitting a cloud of free electrons into the noble gas within the detection chamber. The cloud of electrons is attracted to the opposite end of the detection chamber by a high positive voltage potential at that end and focused onto a sensing anode. If there are impurities in the noble gas, some or all of the electrons within the cloud will bond with the impurity molecules and not reach the sensing anode. Therefore, measuring a lower signal at the sensing anode indicates a higher level of impurities while sensing a higher signal indicates fewer impurities. Impurities in the range of one part per billion can be measured by this device.

  16. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study (United States)

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.


    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar

  17. Liquid scintillation counting of polycarbonates: a sensitive technique for measurement of activity concentration of some radioactive noble gases. (United States)

    Mitev, K; Zhivkova, V; Pressyanov, D; Georgiev, S; Dimitrova, I; Gerganov, G; Boshkova, T


    This work explores the application of the liquid scintillation counting of polycarbonates for measurement of the activity concentration of radioactive noble gases. Results from experimental studies of the method are presented. Potential applications in the monitoring of radioactive noble gases are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Gravity effects on a gliding arc in four noble gases: from normal to hypergravity

    NARCIS (Netherlands)

    Potočňáková, L.; Šperka, J.; Zikán, P.; van Loon, J.J.W.A.; Beckers, J.; Kudrle, V.


    A gliding arc in four noble gases (He, Ne, Ar, Kr) has been studied under previously unexplored conditions of varying artificial gravity, from normal 1 g gravity up to 18 g hypergravity. Significant differences, mainly the visual thickness of the plasma channel, its maximum elongation and general

  19. The determination of accurate dipole polarizabilities alpha and gamma for the noble gases (United States)

    Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almlof, Jan


    Accurate static dipole polarizabilities alpha and gamma of the noble gases He through Xe were determined using wave functions of similar quality for each system. Good agreement with experimental data for the static polarizability gamma was obtained for Ne and Xe, but not for Ar and Kr. Calculations suggest that the experimental values for these latter ions are too low.

  20. Laser microprobe for the study of noble gases and nitrogen in single ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    A laser microprobe capable of analysing nitrogen and noble gases in individual grains with masses less than a milligram is described. It can be ... resulted in attenuation of laser energy reaching the sample surface during successive ... high vacuum (UHV) cleanup system to get low system blanks. Here we report in detail ...

  1. Laser microprobe for the study of noble gases and nitrogen in single ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 112; Issue 1. Laser microprobe for the study of noble gases and nitrogen in single grains: A case study of individual chondrules from the Dhajala meteorite. R R Mahajan S V S Murty. Volume 112 Issue 1 March 2003 pp 113-127 ...

  2. Noble gases in the sediments of Lake Van - solute transport and palaeoenvironmental reconstruction (United States)

    Tomonaga, Yama; Brennwald, Matthias S.; Meydan, Ayşegül F.; Kipfer, Rolf


    Sediment samples acquired in 2010 from the long cores of the International Continental Scientific Drilling Program (ICDP) PaleoVan drilling project on Lake Van for noble-gas analysis in the pore water allow determination of the local terrestrial He-gradient as a function of depth within a sediment column of more than 200 m. These measurements yield first insights into the physical transport mechanisms of terrigenic He through the uppermost part of unconsolidated lacustrine sediments overlying the continental crust. In line with our previous work on the spatial distribution of the terrigenic He release into Lake Van, we identify a high He concentration gradient in the uppermost 10 m of the sediment column. The He concentration gradient decreases below this depth down to approx. 160 m following in general the expectations of the modelling of radiogenic He production and transport in a sediment column with homogeneous fluid transport properties. Overall the in-situ radiogenic He production due to the decay of U and Th in the mineral phases of the sediments accounts for about 80% of the He accumulation. At approx. 190 m we observe a very high He concentration immediately below a large lithological unit characterised by strong deformations. We speculate that this local enrichment is the result of the lower effective diffusivities in the pore space that relate to the abrupt depositional history of this deformed unit. This particular lithological unit seems to act as a barrier that limits the transport of solutes in the pore space and hence might "trap" information on the past geochemical conditions in the pore water of Lake Van. The dissolved concentrations of atmospheric noble gases in the pore waters of the ICDP PaleoVan cores are used to geochemically reconstruct salinity on the time scale of 0-55 ka BP. Higher salinities in the pore water at a depth of about 20 m suggest a significantly lower lake level of Lake Van in the past.

  3. Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication (United States)

    Huss, G. R.; Alexander, E. C., Jr.


    The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.

  4. VAPoR - Volatile Analysis by Pyrolysis of Regolith - an Instrument for In Situ Detection of Water, Noble Gases, and Organics on the Moon (United States)

    ten Kate, I. L.; Cardiff, E. H.; Feng, S. H.; Holmes, V.; Malespin, C.; Stern, J. G.; Swindle, T. D.; Glavin, D. P.


    We present the Volatile Analysis by Pyrolysis of Regolith (VAPoR) instrument design and demonstrate the validity of an in situ pyrolysis mass spectrometer for evolved gas analyses of lunar and planetary regolith samples. In situ evolved gas analyses of the lunar regolith have not yet been carried out and no atmospheric or evolved gas measurements have been made at the lunar poles. VAPoR is designed to do both kinds of measurements, is currently under development at NASA's Goddard Space Flight Center, and will be able to heat powdered regolith samples or rock drill fines up to 1400 C in vacuo. To validate the instrument concept, evolved gas species released from different planetary analogs were determined as a function of temperature using a laboratory breadboard. Evolved gas measurements of an Apollo 16 regolith sample and a fragment of the carbonaceous meteorite Murchison were made by VAPoR and our results compared with existing data. The results imply that in situ evolved gas measurements of the lunar regolith at the polar regions by VAPoR will be a very powerful tool for identifying water and other volatile signatures of lunar or exogenous origin as potential resources for future human exploration.

  5. A generic biokinetic model for noble gases with application to radon. (United States)

    Leggett, Rich; Marsh, James; Gregoratto, Demetrio; Blanchardon, Eric


    To facilitate the estimation of radiation doses from intake of radionuclides, the International Commission on Radiological Protection (ICRP) publishes dose coefficients (dose per unit intake) based on reference biokinetic and dosimetric models. The ICRP generally has not provided biokinetic models or dose coefficients for intake of noble gases, but plans to provide such information for (222)Rn and other important radioisotopes of noble gases in a forthcoming series of reports on occupational intake of radionuclides (OIR). This paper proposes a generic biokinetic model framework for noble gases and develops parameter values for radon. The framework is tailored to applications in radiation protection and is consistent with a physiologically based biokinetic modelling scheme adopted for the OIR series. Parameter values for a noble gas are based largely on a blood flow model and physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions for radon are shown to be consistent with results of controlled studies of its biokinetics in human subjects.

  6. Noble gases in twenty Yamato H-chondrites: Comparison with Allan Hills chondrites and modern falls (United States)

    Loeken, TH.; Scherer, P.; Schultz, L.


    Concentration and isotopic composition of noble gases have been measured in 20 H-chrondrites found on the Yamato Mountains ice fields in Antarctica. The distribution of exposure ages as well as of radiogenic He-4 contents is similar to that of H-chrondrites collected at the Allan Hills site. Furthermore, a comparison of the noble gas record of Antarctic H-chrondrites and finds or falls from non-Antarctic areas gives no support to the suggestion that Antarctic H-chrondrites and modern falls derive from differing interplanetary meteorite populations.

  7. Measuring laser carrier-envelope-phase effects in the noble gases with an atomic hydrogen calibration standard (United States)

    Khurmi, Champak; Wallace, W. C.; Sainadh U, Satya; Ivanov, I. A.; Kheifets, A. S.; Tong, X. M.; Litvinyuk, I. V.; Sang, R. T.; Kielpinski, D.


    We present accurate measurements of carrier-envelope-phase effects on ionization of the noble gases with few-cycle laser pulses. The experimental apparatus is calibrated by using atomic hydrogen data to remove any systematic offsets and thereby obtain accurate CEP data on other generally used noble gases such as Ar, Kr, and Xe. Experimental results for H are well supported by exact time-dependent Schrödinger equation theoretical simulations; however, significant differences are observed in the case of the noble gases.

  8. Contribution of electron-atom collisions to the plasma conductivity of noble gases (United States)

    Rosmej, S.; Reinholz, H.; Röpke, G.


    We present an approach which allows the consistent treatment of bound states in the context of dc conductivity in dense partially ionized noble gas plasmas. Besides electron-ion and electron-electron collisions, further collision mechanisms owing to neutral constituents are taken into account. Especially at low temperatures of 104to105 K, electron-atom collisions give a substantial contribution to the relevant correlation functions. We suggest an optical potential for the description of the electron-atom scattering which is applicable for all noble gases. The electron-atom momentum-transfer cross section is in agreement with experimental scattering data. In addition, the influence of the medium is analyzed, the optical potential is advanced including screening effects. The position of the Ramsauer minimum is influenced by the plasma. Alternative approaches for the electron-atom potential are discussed. Good agreement of calculated conductivity with experimental data for noble gas plasmas is obtained.

  9. Volatiles (H, C, N, O, noble gases) in comets as tracers of early solar system events (Invited) (United States)

    Marty, B.


    Volatiles (H, C, N, O, noble gases) present the largest variations in their relative abundances and, importantly, in their isotopic ratios, among solar system elements. The original composition of the protosolar nebula has been investigated through the measurements of primitive meteorites and of in-situ (e.g. Galileo probe analysis of the Jupiter's atmosphere) and sample-return (Genesis, recovery and analysis of solar wind) missions. The protosolar gas was poor in deuterium, in 15N and in 17,18O. Variations among solar system reservoir reach several hundreds of percents for the D/H and 15N/14N ratios. These variations are possibly : (i) due to interactions between XUV photons of the proto-Sun and the-dust, (ii) result from low temperature ion-molecule reactions, or (iii) constitute an heritage on interstellar volatiles trapped in dust (e.g., organics). Likewise, noble gases are elementally and isotopically (1% per amu for xenon) fractionated with respect to the composition of the solar wind (our best proxy for the protosolar nebula composition). Cometary matter directly measured on coma, or in Stardust material, or in IDPs, seems to present among the largest heterogeneities in their stable isotope compositions but knowledge on their precise compositions of the different phases and species is partial and mosty lacking. Among the several important issues requiring a better knowledge of cometary volatiles are the origin(s) of volatile elements on Earth and Moon, on Mars and on Venus, understanding large scale circulation of matter between hot and frozen zones, and the possibility of interstellar heritage for organics. Critical measurements to be made by the next cometary missions include the value of the D/H ratio in water ice, in NH3 and organics. Nitrogen is particularly interesting as cometary HCN and CN are rich in 15N, but an isotoppe mass balance will require to measure the main host species (N2 ?). Noble gases are excellent tracers of physical processes

  10. Exploring the deep, ancient hydrogeosphere within Precambrian crystalline rocks using noble gases (United States)

    Warr, O.; Sherwood Lollar, B.; Fellowes, J.; Sutcliffe, C. N.; McDermott, J. M.; Holland, G.; Mabry, J.; Ballentine, C. J.


    Serpentinization is a key long-term water-rock interaction occurring within isolated fractures in Precambrian crystalline rocks and is a significant source of global H2 production. Highly saline fracture fluids, containing in-situ produced dissolved gases (e.g. percent level He, abiogenic CH4 and mM H2), have revealed microbial ecosystems isolated from the surface photosphere for millions of years. Noble gases can provide crucial physical and temporal constraints on these serpentinizing and life-supporting environments via radiogenic-derived fluid residence times, while also providing evidence of isolation. New noble gas data is presented here from four locations on the Canadian Shield. Kidd Creek Mine in Ontario, where fluids with a mean residence time ≥ 1.1 Ga were identified in 2013, was revisited with resampling of the waters from 2.4 km bls (below land surface), and new samples collected from 2.9 km bls. The study was also expanded to include two mines from Sudbury, Ontario at 1.7 (Mine 1) and 1.4 (Mine 2) km bls. The radiogenic excesses within the fluids were greatest for the 2.9 km Kidd Creek samples and provided an average residence time of 1.6 Ga. Consistent with our hypothesis, the resampling of the 2.4 km fluids (80 months after the original study) reveal significantly reduced residence times (1.1 Ga to 390 Ma) due to stress-induced opening of younger, though nonetheless old, fractures. This is supported by recent sulphur isotope, and 2H & 18O data. Additional hydrogeological constraints are provided by the 129Xe & 136Xe data, which suggest distinct fracture networks feed the 2.4 km, and the 2.9 km systems. Fracture fluids in the Sudbury Basin were targeted to investigate the influence of a later 1.8 Ga bolide impact which formed major fractures in the underlying basement. As hypothesised the fluids in the Sudbury Archean basement are younger than those at Kidd Creek, with mean residence times of 313 and 544 Ma for Mine 1 and 2 respectively. Our

  11. Noble gases released by vacuum crushing of EETA 79001 glass (United States)

    Wiens, R. C.


    An EETA 79001 glass sample was crushed in a vacuum to observe the gases released. About 15 pct of the total gas concentrations were a mixture of a small amount of SPB-type gas with larger proportions of another air-like component. Less than 5 pct of the SPB gas was released by crushing, while 36-40 pct of the EETV (indigenous) gas was crush-released. The results are consistent with a siting of the EETV component in 10-100 micron vesicles seen in the glass. It is suggested that the SPB component is either in vesicles less than 6 microns in diameter or is primarily sited elsewhere.

  12. Noble gases, stable isotopes, and radiocarbon as tracers of flow in the Dakota aquifer, Colorado and Kansas (United States)

    Clark, J.F.; Davisson, M.L.; Hudson, G.B.; Macfarlane, P.A.


    A suite of chemical and isotope tracers (dissolved noble gases, stable isotopes of water, radiocarbon, and CI) have been analyzed along a flow path in the Dakota aquifer system to determine likely recharge sources, ground water residence times, and the extent of mixing between local and intermediate flow systems, presumably caused by large well screens. Three water types were distinguished with the tracers, each having a very different history. Two of the water types were found in south-eastern Colorado where the Dakota is poorly confined. The tracer data suggest that the first group recharged locally during the last few thousand years and the second group was composed of ground water that recharged earlier during a cooler climate, presumably during the last glacial period (LGP) and mixed aged water. The paleotemperature record archived in this groundwater system indicates that south-eastern Colorado was about 5??C cooler during the LGP than during the late Holocene. Similar temperature changes derived from dissolved noble gases in other aquifer systems have been reported earlier for the south-western United States. The third water type was located down gradient of the first two in the confined Dakota in western and central Kansas. Groundwater residence time of this water mass is on the order of 104-105 yrs and its recharge location is near the Colorado and Kansas border down gradient of the other water types. The study shows the importance of using multiple tracers when investigating ground water systems.A suite of chemical and isotope tracers (dissolved noble gases, stable isotopes of water, radiocarbon, and CL) were analyzed along a flow path in the Dakota aquifer system to determine likely recharge sources, ground water residence times, and the extent of mixing between local and intermediate flow systems. Three water types were distinguished with the tracers, each having a very different history. Two of the water types were located in south-eastern Colorado

  13. Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles (United States)

    Foroutan, Masumeh; Nasrabadi, Amir Taghavi


    In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

  14. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    Energy Technology Data Exchange (ETDEWEB)

    Goodson, Boyd McLean [Univ. of California, Berkeley, CA (United States)


    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.

  15. Noble gases, nitrogen and cosmic ray exposure age of the Sulagiri chondrite

    Directory of Open Access Journals (Sweden)

    Ramakant R. Mahajan


    Full Text Available The Sulagiri meteorite fell in India on 12 September 2008, LL6 chondrite class is the largest among all the Indian meteorites. Isotopic compositions of noble gases (He, Ne, Ar, Kr and Xe and nitrogen in the Sulagiri meteorite and cosmic ray exposure history are discussed. Low cosmogenic (22Ne/21Nec ratio is consistent with irradiation in a large body. Cosmogenic noble gases indicate that Sulagiri has a 4π cosmic-ray exposure (CRE age of 27.9 ± 3.4 Ma and is a member of the peak of CRE age distribution of LL chondrites. Radiogenic 4He and 40Ar concentrations in Sulagiri yields the radiogenic ages as 2.29 and 4.56 Ga, indicating the loss of He from the meteorite. Xenon and krypton are mixture of Q and spallogenic components.

  16. Nuclear Magnetic Resonance of Laser-Polarized Noble Gases in Molecules, Materials, and Organisms (United States)

    Goodson, Boyd M.


    The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI.

  17. High stability breakdown of noble gases with femtosecond laser pulses. (United States)

    Heins, A M; Guo, Chunlei


    In the past, laser-induced breakdown spectroscopy (LIBS) signals have been reported to have a stability independent of the pulse length in solids. In this Letter, we perform the first stability study of femtosecond LIBS in gases (to our best knowledge) and show a significant improvement in signal stability over those achieved with longer pulses. Our study shows that ultrashort-pulse LIBS has an intrinsically higher stability in gas compared to nanosecond-pulse LIBS because of a deterministic ionization process at work in the femtosecond pulse. Relative standard deviations below 1% are demonstrated and are likely only limited by our laser output fluctuations. This enhanced emission stability may open up possibilities for a range of applications, from monitoring rapid gas dynamics to high-quality broadband light sources.

  18. Numerical investigation of enhanced femtosecond supercontinuum via a weak seed in noble gases. (United States)

    Shanor, C; Ensley, T; Hagan, D J; Van Stryland, E W; Wright, E M; Kolesik, M


    Numerical simulations are employed to elucidate the physics underlying the enhanced femtosecond supercontinuum generation previously observed during optical filamentation in noble gases and in the presence of a weak seed pulse. Simulations based on the metastable electronic state approach are shown not only to capture the qualitative features of the experiment, but also reveal the relation of the observed enhancement to recent developments in the area of sub-cycle engineering of filaments.

  19. The desorption of condensed noble gases and gas mixtures from cryogenic surfaces

    CERN Document Server

    Tratnik, H; Störi, H


    In accelerators, operating at liquid-helium temperature, cold surfaces are exposed to intense synchrotron radiation and bombardment by energetic electrons and ions. Molecular desorption yield and secondary electron yield can strongly influence the performance of the accelerator. In order to predict the gas density during the operation, the knowledge of electron-induced desorption yields of condensed gases and of its variation with the gas coverage is necessary. Desorption yields under electron impact of various noble gases and gas mixtures condensed on a copper surface cooled at 4.2 K have been measured.

  20. The role of van der Waals interactions in the adsorption of noble gases on metal surfaces. (United States)

    Chen, De-Li; Al-Saidi, W A; Johnson, J Karl


    Adsorption of noble gases on metal surfaces is determined by weak interactions. We applied two versions of the nonlocal van der Waals density functional (vdW-DF) to compute adsorption energies of Ar, Kr, and Xe on Pt(111), Pd(111), Cu(111), and Cu(110) metal surfaces. We compared our results with data obtained using other density functional approaches, including the semiempirical vdW-corrected DFT-D2. The vdW-DF results show considerable improvements in the description of adsorption energies and equilibrium distances over other DFT based methods, giving good agreement with experiments. We also calculated perpendicular vibrational energies for noble gases on the metal surfaces using vdW-DF data and found excellent agreement with available experimental results. Our vdW-DF calculations show that adsorption of noble gases on low-coordination sites is energetically favored over high-coordination sites, but only by a few meV. Analysis of the two-dimensional potential energy surface shows that the high-coordination sites are local maxima on the two-dimensional potential energy surface and therefore unlikely to be observed in experiments; this provides an explanation of the experimental observations. The DFT-D2 approach with the standard parameterization was found to overestimate the dispersion interactions, and to give the wrong adsorption site preference for four of the nine systems we studied.

  1. Nitrogen and noble gases in a glass sample from the LEW88516 shergottite (United States)

    Becker, Richard H.; Pepin, Robert O.


    A glass separate from the LEW88516 shergottite was analyzed by step-wise combustion for N and noble gases to determine whether it contained trapped gas similar in composition to the martian atmosphere-like component previously observed in lithology C of EETA79001. Excesses of Ar-40 and Xe-129 were in fact observed in this glass, although the amounts of these excesses less than or = to 20% of those seen in the latter meteorite, and are comparable to the amounts seen in whole-rock analyses of LEW88516. The isotopic composition of N in LEW88516 does not show an enrichment in delta N-15 commensurate with the amount of isotopically-heavy N expected from the noble gases excesses. One must posit some extreme assumptions about the nature of the N components present in LEW88516 in order to allow the presence of the trapped nitrogen component. Alternatively, the N has somehow been decoupled from the noble gases, and was either never present of has been lost.

  2. The role of van der Waals interactions in the adsorption of noble gases on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Chen, De-Li; Al-Saidi, W A; Johnson, J Karl


    Adsorption of noble gases on metal surfaces is determined by weak interactions. We applied two versions of the nonlocal van der Waals density functional (vdW-DF) to compute adsorption energies of Ar, Kr, and Xe on Pt(111), Pd(111), Cu(111), and Cu(110) metal surfaces. We have compared our results with data obtained using other density functional approaches, including the semiempirical vdW corrected DFT-D2. The vdW-DF results show considerable improvements in the description of adsorption energies and equilibrium distances over other DFTbased methods, giving good agreement with experiments. We have also calculated perpendicular vibrational energies for noble gases on the metal surfaces using vdWDF data and found excellent agreement with available experimental results. Our vdW-DF calculations show that adsorption of noble gases on low-coordination sites is energetically favored over high-coordination sites, but only by a few meV. Analysis of the 2-dimensional potential energy surface shows that the high-coordination sites are local maxima on the 2-dimensional potential energy surface and therefore unlikely to be observed in experiments, which provides an explanation of the experimental observations. The DFT-D2 approach with the standard parameterization was found to overestimate the dispersion interactions, and to give the wrong adsorption site preference for four of the nine systems we studied.

  3. Radiative precursors driven by converging blast waves in noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); and others


    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s{sup −1} blast waves through gases of densities of the order 10{sup −5} g cm{sup −3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  4. Noble gases as tracers of the origin and evolution of the Martian atmosphere and the degassing history of the planet (United States)

    Swindle, T. D.


    Noble gas analysis of Martian samples can provide answers to a number of crucial questions. Some of the most obvious benefits will be in Martian chronology, using techniques that have been applied to lunar samples. However, these are by no means the only relevant noble gas studies possible. Since Mars has a substantial atmosphere, noble gases can be used to study the origin and evolution of that atmosphere, including the degassing history of the planet. This type of study can provide constraints on: (1) the total noble gas inventory of the planet, (2) the number of noble gas reservoirs existing, and (3) the exchange of gases between these reservoirs. How to achieve these goals are examined.

  5. Noble gases in presolar diamonds I: Three distinct components and their implications for diamond origins (United States)

    Huss, Gary R.; Lewis, Roy S.


    High-purity separates of presolar diamond were prepared from 14 primitive chondrites from 7 compositional groups. Their noble gases were measured using stepped pyrolysis. Three distinct noble gas components are present in diamonds, HL, P3, and P6, each of which is found to consist of five noble gases. P3, released between 200 C and 900 C, has a 'planetary' elemental abundance pattern and roughly 'normal' isotopic ratios. HL, consisting of isotopically anomalous Xe-HL and Kr-H, Ar with high Ar-38/Ar-36, and most of the gas making up Ne-A2 and He-A, is released between 1100 C and 1600 C. HL has 'planetary' elemental ratios, except that it has much more He and Ne than other known 'planetary' components. HL gases are carried in the bulk diamonds, not in some trace phase. P6 has a slightly higher median release temperature than HL and is not cleanly separated from HL by stepped pyrolysis. Our data suggest that P6 has roughly 'normal' isotopic compositions and 'planetary' elemental ratios. Both P3 and P6 seem to be isotopically distinct from P1, the dominant 'planetary' noble-gas component in primitive chondrites. Release characteristics suggest that HL and P6 are sited in different carriers within the diamond fractions, while P3 may be sited near the surfaces of the diamonds. We find no evidence of separability of Xe-H and Xe-L or other isotopic variations in the HL component. However, because approximately 10(exp 10) diamonds are required to measure a Xe composition, a lack of isotopic variability does not constrain diamonds to come from a single source. In fact, the high abundance of diamonds in primitive chondrites and the presence of at least three distinct noble-gas components strongly suggest that diamonds originated in many sources. Relative abundances of noble-gas components in diamonds correlate with degree of thermal processing, indicating that all meteorites sampled essentially the same mixture of diamonds. That mixture was probably inherited from the Sun

  6. Noble gases in the coma of comet 67P/Churyumov-Gerasimenko (United States)

    Rubin, M.


    The European Space Agency's Rosetta mission accompanied comet 67P/Churyumov-Gerasimenko (67P) for over two years along its orbit around the Sun. Comets are among the most pristine objects in our solar system. Investigating their composition was one of the main goals of the Rosetta mission. Abundances and isotopic ratios of the different volatile species provide crucial insights into the physical and chemical conditions during and possibly even before the comet's formation in the early solar system. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) consisted of a pressure sensor and two mass spectrometers and was dedicated to the detection of volatiles in the coma of 67P. Already early in mission, in October 2014, ROSINA detected the noble gas argon at the comet. Then late in the mission in May 2016, after an intense phase of gas and dust activity around the perihelion, Rosetta spent several weeks within 7 to 10 km of 67P. These conditions allowed the detection of additional noble gases - krypton and xenon. In this presentation, we will report on our latest results from the investigation of the relative abundances and the isotopic ratios of these noble gases measured in the coma of 67P.

  7. Observations of mass fractionation of noble gases in synthetic methane hydrate (United States)

    Hunt, Andrew G.; Pohlman, John; Stern, Laura A.; Ruppel, Carolyn D.; Moscati, Richard J.; Landis, Gary P.; Pinkston, John C.


    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings are presently dissociating and releasing methane and other gases to the oceanatmosphere system. A key challenge in assessing the susceptibility of gas hydrates to warming climate is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sublake and subseafloor sediments, coalbeds, and other sources. Carbon and deuterium stable isotopic data provide only a first-order characterization of methane sources, while gas hydrate can sequester any type of methane. Here, we investigate the possibility of exploiting the pattern of noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under careful laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  8. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation (United States)

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.


    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  9. Noble gases, nitrogen, and methane from the deep interior to the atmosphere of Titan (United States)

    Glein, Christopher R.


    Titan's thick N2-CH4 atmosphere is unlike any in the Solar System, and its origin has been shrouded in mystery for over half a century. Here, I perform a detailed analysis of chemical and isotopic data from the Cassini-Huygens mission to develop the hypothesis that Titan's (non-photochemical) atmospheric gases came from deep within. It is suggested that Titan's CH4, N2, and noble gases originated in a rocky core buried inside the giant satellite, and hydrothermal and cryovolcanic processes were critical to the creation of Titan's atmosphere. Mass balance and chemical equilibrium calculations demonstrate that all aspects of this hypothesis can be considered geochemically plausible with respect to contemporary observational, experimental, and theoretical knowledge. Specifically, I show that a rocky core with a bulk noble gas content similar to that in CI carbonaceous meteorites would contain sufficient 36Ar and 22Ne to explain their reported abundances. I also show that Henry's law constants for noble gases in relevant condensed phases can be correlated with the size of their atoms, which leads to expected mixing ratios for 84Kr (∼0.2 ppbv) and 132Xe (∼0.01 ppbv) that can explain why these species have yet to be detected (Huygens upper limit <10 ppbv). The outgassing of volatiles into Titan's atmosphere may be restricted by the stability of clathrate hydrates in Titan's interior. The noble gas geochemistry also provides significant new insights into the origin of N2 and CH4 on Titan, as I find that Ar and N2, and Kr and CH4 should exhibit similar phase partitioning behavior on Titan. One implication is that over 95% of Titan's N2 may still reside in the interior. Another key result is that the upper limit from the Huygens GC-MS on the Kr/CH4 ratio in Titan's atmosphere is far too low to be consistent with accretion of primordial CH4 clathrate, which motivates me to consider endogenic production of CH4 from CO2 as a result of geochemical reactions between liquid

  10. Trace analysis of aerosol bound particulates and noble gases at the BfS in Germany. (United States)

    Bieringer, J; Schlosser, C; Sartorius, H; Schmid, S


    The Federal Office for Radiation Protection (BfS) performs trace analysis measurements in both the frameworks of the German Integrated Measuring and Information system as well as of the International Monitoring System for verification of the Comprehensive Nuclear-Test-Ban Treaty. Therefore, different kinds of measurements of aerosol bound radionuclides as well as of radioactive noble gases in the atmosphere are performed. BfS as coordinating laboratory for trace analysis is responsible for the quality control. A quality assurance programme was set up with German institutions and expanded to European laboratories. The existing quality assurance programme of the Comprehensive Nuclear-Test-Ban Treaty Organisation for measurements of aerosol bound radionuclides will be extended for noble gas measurements. Applied methods, achieved measurement results and the different kinds of quality assurance are presented and discussed.

  11. Solar noble gases revealed by closed system stepped etching of a metal separate from Fayetteville (United States)

    Murer, CH.; Baur, H.; Signer, P.; Wieler, R.


    Solar He, Ne, and Ar in a Fe-Ni separate from the chondrite Fayetteville are analyzed by closed system stepped oxidation. We report here data of the first 15 steps comprising 55 percent of the total solar gases. He-4/Ar-36 and Ne-20/Ar-36 are quite constant at values about 20 percent below those of present day solar wind (SWC). In this, Fe-Ni differs from lunar ilmenites where He-4/Ar-36 and Ne-20/Ar-36 in the first steps are several times below SWC. Thus, metal retains SW-noble gases even better than ilmenite, almost without element fractionation. Nevertheless, the isotopic composition of SW-He, -Ne, and -Ar in the first steps of the metal sample are identical to those found in a recently irradiated lunar ilmenite, indicating that ilmenites and chondritic metal both contain isotopically unfractionated SW noble gases. A preliminary analysis of a smaller Fayetteville metal separate shows Ne from solar energetic particles (SEP-Ne) with Ne-20/Ne-22 less than or equal to 11.5.

  12. Protonated ions as systemic trapping agents for noble gases: From electronic structure to radiative association (United States)

    Ozgurel, O.; Pauzat, F.; Pilmé, J.; Ellinger, Y.; Bacchus-Montabonel, M.-C.; Mousis, O.


    The deficiencies of argon, krypton, and xenon observed in the atmosphere of Titan as well as anticipated in some comets might be related to a scenario of sequestration by H3+ in the gas phase at the early evolution of the solar nebula. The chemical process implied is a radiative association, evaluated as rather efficient in the case of H3+, especially for krypton and xenon. This mechanism of chemical trapping might not be limited to H3+ only, considering that the protonated ions produced in the destruction of H3+ by its main competitors present in the primitive nebula, i.e., H2O, CO, and N2, might also give stable complexes with the noble gases. However the effective efficiency of such processes is still to be proven. Here, the reactivity of the noble gases Ar, Kr, and Xe, with all protonated ions issued from H2O, CO, and N2, expected to be present in the nebula with reasonably high abundances, has been studied with quantum simulation method dynamics included. All of them give stable complexes and the rate coefficients of their radiative associations range from 10-16 to 10-19 cm3 s-1, which is reasonable for such reactions and has to be compared to the rates of 10-16 to 10-18 cm3 s-1, obtained with H3+. We can consider this process as universal for all protonated ions which, if present in the primitive nebula as astrophysical models predict, should act as sequestration agents for all three noble gases with increasing efficiency from Ar to Xe.

  13. Calibration of stack monitors for measurement of noble gases in nuclear facilities. (United States)

    Kovar, Petr; Dryak, Pavel; Suran, Jiri; Gudelis, Arunas


    In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors. For efficiency calibration a standard with the radionuclide Xe-127 was developed and calibration curve constructed in the energy range 81 keV-1293 keV. Experiental efficiencies were checked using an MC model. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Enhancement of NMR and MRI in the presence of hyperpolarized noble gases (United States)

    Pines, Alexander; Budinger, Thomas; Navon, Gil; Song, Yi-Qiao; Appelt, Stephan; Bifone, Angelo; Taylor, Rebecca; Goodson, Boyd; Seydoux, Roberto; Room, Toomas; Pietrass, Tanja


    The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

  15. Noble gases in separated meteoritic minerals - Murchison /C2/, Ornans /C3/, Karoonda /C5/, and Abee /E4/ (United States)

    Srinivasan, S.; Gros, J.; Anders, E.


    The distribution of all five noble gases was measured in four meteorites of different classes by mass spectrometry and stepwise heating of HCl-HF-insoluble residues and of samples treated with HNO3 and atomic oxygen. The distribution of the gases among the three main phases, chromite, polymer, and the ill-defined Q-phase, was determined, and also the isotopic distribution of the gases in the phases was obtained.

  16. Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Velişa, Gihan, E-mail: [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, 077125 Magurele (Romania); Debelle, Aurélien; Thomé, Lionel; Mylonas, Stamatis [Centre de Sciences Nucléaires et de Sciences de la Matière, CNRS-IN2P3-Université Paris-Sud, Bât. 108, F-91405 Orsay (France); Vincent, Laetitia [Centre de Sciences Nucléaires et de Sciences de la Matière, CNRS-IN2P3-Université Paris-Sud, Bât. 108, F-91405 Orsay (France); Institut d’Electronique Fondamentale, Université Paris-Sud, UMR 8622, Bât. 220, 91405 Orsay (France); Boulle, Alexandre [Science des Procédés Céramiques et de Traitements de Surface, CNRS UMR 7315, Centre Européen de la Céramique, 12 rue Atlantis, 87068 Limoges (France); Jagielski, Jacek [Institute for Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); National Center for Nuclear Research, PL-05-400 Swierk/Otwock (Poland); Pantelica, Dan [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, 077125 Magurele (Romania)


    The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

  17. Noble Gases in Two Fragments of Different Lithologies from the Almahata Sitta Meteorite (United States)

    Nagao, K.; Haba, M. K.; Zolensky, M.; Jenniskens, P.; Shaddad, M. H.


    The Almahata Sitta meteorite, whose preat-mospheric body was the asteroid 2008 TC3, fell on October 7, 2008 in the Nubian Desert in northern Sudan [e.g., 1, 2]. Numer-ous fragments have been recovered during several expeditions organized from December 2008 [2]. The meteorite was classified as an anomalous polymict ureilite with several different kinds of chondritic fragments [e.g., 3-5]. Noble gas studies performed on several fragments from the meteorite showed cosmic-ray expo-sure ages of about 20 My [e.g., 6-8], although slightly shorter ages were also reported in [9, 10]. Concentrations of trapped heavy noble gases are variable among the fragments of different lithologies [9, 10]. We report noble gas data on two samples from the #1 and #47 fragments [2], which were the same as those re-ported by Ott et al. [9]. Experimental Procedure: Weights of bulk samples #1 and #47 used in this work were 16.1 mg and 17.6 mg, respectively. Noble gases were extracted by stepwise heating at the tempera-tures of 800, 1200 and 1800°C for #1 and 600, 800, 1000, 1200, 1400, 1600 and 1800°C for #47. Concentrations and isotopic ra-tios of noble gases were measured with a modified-VG5400/MS-III at the Geochemical Research Center, University of Tokyo. Results and Discussion: Cosmogenic He and Ne are domi-nant in both #1 and #47, but trapped Ar, Kr and Xe concentra-tions are much higher in #47 than in #1, showing that noble gas compositions in #47 are similar to those of ureilites. 3He/21Ne and 22Ne/21Ne of cosmogenic He and Ne are 4.8 and 1.12 for #1 and 3.6 and 1.06 for #47, respectively, both of which plot on a Bern line [11]. This indicates negligible loss of cosmogenic 3He from #1 in our sample, unlike the low 3He/21Ne of 3.1 for #1 by Ott et al. [9]. Concentrations of cosmogenic 3He and 21Ne (10-8 cc/g) are 30 and 6.3 for #1 and 32 and 9.0 for #47, respectively, which are higher than those in [9] and give cosmic-ray exposure ages of ca. 20 My depending on assumed production

  18. Investigation of Lung Structure-Function Relationships Using Hyperpolarized Noble Gases (United States)

    Thomen, Robert P.

    Magnetic Resonance Imaging (MRI) is an application of the nuclear magnetic resonance (NMR) phenomenon to non-invasively generate 3D tomographic images. MRI is an emerging modality for the lung, but it suffers from low sensitivity due to inherent low tissue density and short T(*/2) . Hyperpolarization is a process by which the nuclear contribution to NMR signal is greatly enhanced to more than 100,000 times that of samples in thermal equilibrium. The noble gases 3He and 129Xe are most often hyperpolarized by transfer of light angular momentum through the electron of a vaporized alkali metal to the noble gas nucleus (called Spin Exchange Optical Pumping). The enhancement in NMR signal is so great that the gas itself can be imaged via MRI, and because noble gases are chemically inert, they can be safely inhaled by a subject, and the gas distribution within the interior of the lung can be imaged. The mechanics of respiration is an elegant physical process by which air is is brought into the distal airspaces of the lungs for oxygen/carbon dioxide gas exchange with blood. Therefore proper description of lung function is intricately related to its physical structure , and the basic mechanical operation of healthy lungs -- from pressure driven airflow, to alveolar airspace gas kinetics, to gas exchange by blood/gas concentration gradients, to elastic contraction of parenchymal tissue -- is a process decidedly governed by the laws of physics. This dissertation will describe experiments investigating the relationship of lung structure and function using hyperpolarized (HP) noble gas MRI. In particular HP gases will be applied to the study of several pulmonary diseases each of which demonstrates unique structure-function abnormalities: asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Successful implementation of an HP gas acquisition protocol for pulmonary studies is an involved and stratified undertaking which requires a solid theoretical foundation in NMR

  19. A theoretical study of the cohesion of noble gases on graphite. (United States)

    Bichoutskaia, Elena; Pyper, Nicholas C


    The interactions of the noble gases with a graphene sheet are investigated theoretically. The short range repulsive interaction between the noble gas and each carbon atom is described using Hartree-Fock atomic densities and a local density functional theory with the exchange functional corrected for the finite range of the interaction by introducing a Rae-type correction depending on the effective number of electrons. The long range interactions are introduced as the sum of the Axilrod-Teller triple-dipole interaction plus the dipole-dipole and dipole-quadrupole dispersive attractions damped according to the theory of Jacobi and Csanak. The energy arising from the interactions between the permanent quadrupoles on the carbon atoms with the dipole they induce on the noble gas is negligible, being nonzero only on account of the atomistic structure of graphene. The mobile and delocalized nature of the graphene pi electrons causes the effective number of electrons to be around 500 rather than that of 12 appropriate for a system of entirely localized interactions with individual carbon atoms. Inclusion of the Axilrod-Teller term is required to obtain reliable predictions for the binding energies and equilibrium geometries. Absorption of a noble gas atom is predicted to occur at the site above the center of a six membered ring although this is preferred over two other sites by only about 5 meV. The methods presented for generating all the potentials can be applied to derive the interactions between any ion and carbon atom in the wall of a single-walled nanotube. Knowledge of these interactions is required to study the alkali halide nanocrystals encapsulated in single-walled carbon nanotubes of current interest.

  20. Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors. (United States)

    McWilliams, R Stewart; Dalton, D Allen; Konôpková, Zuzana; Mahmood, Mohammad F; Goncharov, Alexander F


    The noble gases are elements of broad importance across science and technology and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laser-heated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000-15,000 K and pressures of 15-52 GPa. The thermal activation and frequency dependence of conduction reveal an optical character dominated by electrons of low mobility, as in an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free electrons. Helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with its increased solubility in metallic hydrogen, whereas a deep layer of insulating neon may inhibit core erosion in Saturn.

  1. Atmospheric noble gases in Mid-Ocean Ridge Basalts: Identification of atmospheric contamination processes (United States)

    Roubinet, Claire; Moreira, Manuel A.


    Noble gases in oceanic basalts always show the presence in variable proportions of a component having elemental and isotopic compositions that are similar to those of the atmosphere and distinct from the mantle composition. Although this component could be mantle-derived (e.g. subduction of air or seawater-derived noble gases trapped in altered oceanic crust and sediments), it is most often suggested that this air component is added after sample collection and probably during storage at ambient air, although the mechanism remains unknown. In an attempt to reduce this atmospheric component observed in MORBs, four experimental protocols have been followed in this study. These protocols are based on the hypothesis that air can be removed from the samples, as it appears to be sheltered in distinct vesicles compared to those filled with mantle gases. All of the protocols involve a glove box filled with nitrogen, and in certain cases, the samples are stored under primary vacuum (lower than 10-2 mbar) to pump air out or, alternatively, under high pressure of N2 to expel atmospheric noble gases. In all protocols, three components are observed: atmospheric, fractionated atmospheric and magmatic. The fractionated air component seems to be derived from the non-vitreous part of the pillow-lava, which has cooled more slowly. This component is enriched in Ne relative to Ar, reflecting a diffusive process. This contaminant has already been observed in other studies and thus seems to be relatively common. Although it is less visible, unfractionated air has also been detected in some crushing steps, which tends to indicate that despite the experiments, air is still present in the vesicles. This result is surprising, since studies have demonstrated that atmospheric contamination could be limited if samples were stored under nitrogen quickly after their recovery from the seafloor. Thus, the failure of the protocols could be explained by the insufficient duration of these protocols or

  2. Solar wind noble gases and nitrogen in metal from lunar soil 68501 (United States)

    Becker, Richard H.; Pepin, Robert O.


    Noble gases and N were analyzed in handpicked metal separates from lunar soil 68501 by a combination of step-wise combustions and pyrolyses. Helium and Ne were found to be unfractionated with respect to one another when normalized to solar abundances, for both the bulk sample and for all but the highest temperature steps. However, they are depleted relative to Ar, Kr and Xe by at least a factor of 5. The heavier gases exhibit mass-dependent fractionation relative to solar system abundance ratios but appear unfractionated, both in the bulk metal and in early temperature steps, when compared to relative abundances derived from lunar ilmenite 71501 by chemical etching, recently put forward as representing the abundance ratios in solar wind. Estimates of the contribution of solar energetic particles (SEP) to the originally implanted solar gases, derived from a basic interpretation of He and Ne isotopes, yield values of about 10%. Analysis of the Ar isotopes requires a minimum of 20% SEP, and Kr isotopes, using our preferred composition for solar wind Kr, yield a result that overlaps both these values. It is possible to reconcile the data from these gases if significant loss of solar wind Ar, Kr and presumably Xe has occurred relative to the SEP component, most likely by erosive processes that are mass independent, although mass-dependent losses (Ar greater than Kr greater than Xe) cannot be excluded. If such losses did occur, the SEP contribution to the solar implanted gases must have been no more than a few percent. Nitrogen is a mixture of indigenous meteoritic N, whose isotopic composition is inferred to be relatively light, and implanted solar N, which has probably undergone diffusive redistribution and fractionation. If the heavy noble gases have not undergone diffusive loss, then N/Ar in the solar wind can be inferred to be at least several times the accepted solar ratio. The solar wind N appears, even after correction for fractionation effects, to have a minimum

  3. Ionization-induced laser-driven QED cascade in noble gases (United States)

    Artemenko, I. I.; Kostyukov, I. Yu.


    A formula for the ionization rate in an extremely intense electromagnetic field is proposed and used for numerical study of QED cascades in noble gases in the field of two counterpropagating laser pulses. It is shown that the number of the electron-positron pairs produced in the cascade increases with the atomic number of the gas, where the gas density is taken to be inversely proportional to the atomic number. While most of the electrons produced in the laser pulse front are expelled by the ponderomotive force from the region occupied by the strong laser field, there is a small portion of electrons staying in the laser field for a long time until the instance when the laser field is strong enough for cascading. This mechanism is relevant for all gases. For high-Z gases there is an additional mechanism associated with the ionization of inner shells at the instance when the laser field is strong enough for cascading. The role of both mechanisms for cascade initiation is revealed.

  4. Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures

    CERN Document Server

    Azevedo, C.D.R.


    A study of the gas pressure effect in the position resolution of an interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic position resolution for pure noble gases (Argon and Xenon) and their mixtures with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for photon energies between 5.4 and 60.0 keV, being possible to establish a linear match between the intrinsic position resolution and the inverse of the gas pressure in that energy range. In order to evaluate the quality of the method here described, a comparison between the available experimental data and the calculated one in this work, is done and discussed. In the majority of the cases, a strong agreement is observed.

  5. A method for calibrating coil constants by using the free induction decay of noble gases

    Directory of Open Access Journals (Sweden)

    Linlin Chen


    Full Text Available We propose a precise method to calibrate the coil constants of spin-precession gyroscopes and optical atomic magnetometers. This method is based on measuring the initial amplitude of Free Induction Decay (FID of noble gases, from which the π/2 pulse duration can be calculated, since it is inversely proportional to the amplitude of the π/2 pulse. Therefore, the coil constants can be calibrated by measuring the π/2 pulse duration. Compared with the method based on the Larmor precession frequency of atoms, our method can avoid the effect of the pump and probe powers. We experimentally validated the method in a Nuclear Magnetic Resonance Gyroscope (NMRG, and the experimental results show that the coil constants are 436.63±0.04 nT/mA and 428.94±0.02 nT/mA in the x and y directions, respectively.

  6. Shock-implanted noble gases. II - Additional experimental studies and recognition in naturally shocked terrestrial materials (United States)

    Bogard, Donald; Horz, Friedrich; Johnson, Pratt


    The process by which ambient gases can be implanted into silicates by shocks was investigated by analyzing the noble-gas content of several experimentally and naturally shocked silicate samples. The retentivity of shock-implanted gas during stepwise heating in the laboratory was defined in terms of two parameters, namely, the activation energy for diffusion and the extraction temperature at which 50 percent of the gas is released, both of which correlate with the shock pressure. The experiments indicate that, with increasing shock pressure, gas implantation occurs through an increasing production of microcracks/defects in the silicate lattice. The degree of annealing of these defects control the degree of diffusive loss of implanted gas.

  7. A method for calibrating coil constants by using the free induction decay of noble gases (United States)

    Chen, Linlin; Zhou, Binquan; Lei, Guanqun; Wu, Wenfeng; Wang, Jing; Zhai, Yueyang; Wang, Zhuo; Fang, Jiancheng


    We propose a precise method to calibrate the coil constants of spin-precession gyroscopes and optical atomic magnetometers. This method is based on measuring the initial amplitude of Free Induction Decay (FID) of noble gases, from which the π /2 pulse duration can be calculated, since it is inversely proportional to the amplitude of the π /2 pulse. Therefore, the coil constants can be calibrated by measuring the π /2 pulse duration. Compared with the method based on the Larmor precession frequency of atoms, our method can avoid the effect of the pump and probe powers. We experimentally validated the method in a Nuclear Magnetic Resonance Gyroscope (NMRG), and the experimental results show that the coil constants are 436.63 ±0.04 nT/mA and 428.94 ±0.02 nT/mA in the x and y directions, respectively.

  8. IR spectra of halothane-acetone complex in liquefied noble gases (Kr and Xe) (United States)

    Melikova, S. M.; Rutkowski, K. S.; Rospenk, M.


    IR absorption spectra of solutions of halothane (C2HBrClF3) and acetone ((CD3)2CO) mixtures in liquefied noble gases (krypton and xenon) have been recorded and analyzed. Bands due to weak hydrogenbonded complexes are identified. The complex-formation enthalpy is estimated in a series of temperature experiments on the change in the total intensity of the bands due to monomers and complexes. Second-order bands are found, which are assigned to the first overtone of stretching vibration CH of halothane and the Raman band related to simultaneous excitation of stretching vibration CH of halothane and stretching vibration CO of acetone. The results of ab initio calculation performed within the MP2/6-311++G(d, p) approximation are used to analyze the spectroscopic data.

  9. A Complex Exposure History of the Gold Basin L4-Chondrite Shower from Cosmogenic Radionuclides and Noble Gases (United States)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Masarik, J.; Wieler, R.


    Cosmogenic radionuclides and noble gases in samples of the Gold Basin L-chondrite shower indicate a complex exposure history, with a first stage exposure on the parent body, followed by a second stage of approx. 19 Myr in a meteoroid 3-4 m in radius. Additional information is contained in the original extended abstract.

  10. Noble gases in presolar diamonds II: Component abundances reflect thermal processing (United States)

    Huss, Gary R.; Lewis, Roy S.


    Using the isotopic compositions derived in Huss and Lewis, 1994a, abundances of the P3, HL, and P6 noble-gas components were determined for 15 diamonds separates from primitive chondrites of 8 chondrite classes. Within a meteorite class, the relative abundances of these components correlate with the petrologic subtype of the host meteorite, indicating that metamorphism is primarily responsible for the variations. Relative abundances of P3, HL, and P6 among diamond samples can be understood in terms of thermal processing of a single mixture of diamonds like those now found in CI and CM2 chondrites. With relatively gentle heating, primitive diamonds first lose their low-temperature P3 gases and a 'labile' fraction of the HL component. Mass loss associated with release of these components produces an increase in the HL and P6 content of the remaining diamond relative to unprocessed diamond. Higher temperatures initiate destruction of the main HL carrier, while the HL content of the surviving diamonds remains essentially constant. At the same time, the P6 carrier begins to preferentially lose light noble gases. Meteorites that have experienced metamorphic temperatures greater than or = 650 C have lost essentially all of their presolar diamond through chemical reactions with surrounding minerals. The P3 abundance seems to be a function only of the maximum temperature experienced by the diamonds and thus is independent of the nature of the surrounding environment. If all classes inherited the same mixture of primitive diamonds, then P3 abundances would tie together the metamorphic scales in different meteorite classes. However, if the P3 abundance indicates a higher temperature than do other thermometers applicable to the host meteorite, then the P3 abundance may contain information about heating prior to accretion. Diamonds in the least metamorphosed EH, CV, and CO chondrites seem to carry a record of pre-accretionary thermal processing.

  11. The Preparation and Use of Short Half-Lived Radioactive Noble Gases in Nuclear Medicine. (United States)

    Dahl, J. Robert


    Radioisotopes of noble gases have been widely used for biomedical studies for many years, in particular for lung function studies and for studies of patients with coronary artery disease. ^{rm 79m}Kr (T_{1over2 } = 50s) emits 130 keV gamma rays in 27% of its disintegrations, ^{rm 127m }Xe (T_{1over2} = 69.2s) emits a 172.5 keV gamma ray in 38% of its disintegrations and a 124.8 keV gamma ray in 69% of its disintegrations and ^{19} Ne (T_{1over2} = 17.1s) decays 99.1% by positron emission. The energy of the ^{rm 79m}Kr gamma ray and of the more abundant ^{ rm 127m}Xe 124.8 keV gamma ray is sufficiently close to the 140.5 keV gamma energy of ^ {rm 99m}Tc to provide images of similar quality using present equipment. Neon-19 offers potential for ventilation studies and regional blood flow measurements using positron emission tomography (PET). The increasing number of small medical cyclotrons provides the alternative of utilizing very short half-lived radioactive noble gases such as ^{rm 79m }Kr, ^{rm 127m} Xe, and ^{19}Ne. A procedure has been developed for preparing these radionuclides by bombarding aqueous solutions of alkali metal halides with 14 MeV protons, using a helium sweep gas to remove the products as they are produced. A target design, production rates, methods of quality control, delivery and use of the ^{rm 79m}Kr and ^{rm 127m}Xe are given. A new method for preparing ^ {19}Ne is presented.

  12. The Efficacy of Noble Gases in the Attenuation of Ischemia Reperfusion Injury: A Systematic Review and Meta-Analyses. (United States)

    De Deken, Julie; Rex, Steffen; Monbaliu, Diethard; Pirenne, Jacques; Jochmans, Ina


    Noble gases have been attributed to organ protective effects in ischemia reperfusion injury in a variety of medical conditions, including cerebral and cardiac ischemia, acute kidney injury, and transplantation. The aim of this study was to appraise the available evidence by systematically reviewing the literature and performing meta-analyses. PubMed, EMBASE, and the Cochrane Library. Inclusion criteria specified any articles on noble gases and either ischemia reperfusion injury or transplantation. In vitro studies, publications without full text, review articles, and letters were excluded. Information on noble gas, organ, species, model, length of ischemia, conditioning and noble gas dose, duration of administration of the gas, endpoints, and effects was extracted from 79 eligible articles. Study quality was evaluated using the Jadad scale. Effect sizes were extracted from the articles or retrieved from the authors to allow meta-analyses using the random-effects approach. Argon has been investigated in cerebral, myocardial, and renal ischemia reperfusion injury; helium and xenon have additionally been tested in hepatic ischemia reperfusion injury, whereas neon was only explored in myocardial ischemia reperfusion injury. The majority of studies show a protective effect of these noble gases on ischemia reperfusion injury across a broad range of experimental conditions, organs, and species. Overall study quality was low. Meta-analysis for argon was only possible in cerebral ischemia reperfusion injury and did not show neuroprotective effects. Helium proved neuroprotective in rodents and cardioprotective in rabbits, and there were too few data on renal ischemia reperfusion injury. Xenon had the most consistent effects, being neuroprotective in rodents, cardioprotective in rodents and pigs, and renoprotective in rodents. Helium and xenon show organ protective effects mostly in small animal ischemia reperfusion injury models. Additional information on timing, dosing, and

  13. Neuroprotection (and lack of neuroprotection) afforded by a series of noble gases in an in vitro model of neuronal injury. (United States)

    Jawad, Noorulhuda; Rizvi, Maleeha; Gu, Jianteng; Adeyi, Olar; Tao, Guocai; Maze, Mervyn; Ma, Daqing


    Xenon-induced neuroprotection has been well studied both in vivo and in vitro. In this study, the neuroprotective properties of the other noble gases, namely, krypton, argon, neon and helium, were explored in an in vitro model of neuronal injury. Pure neuronal cultures, derived from foetal BALB/c mice cortices, were provoked into injury by oxygen and glucose deprivation (OGD). Cultures were exposed to either nitrogen hypoxia or noble gas hypoxia in balanced salt solution devoid of glucose for 90min. The cultures were allowed to recover in normal culture medium for a further 24h in nitrogen or noble gas. The effect of noble gases on cell reducing ability in the absence of OGD was also investigated. Cell reducing ability was quantified via an MTT assay and expressed as a ratio of the control. The OGD caused a reduction in cell reducing ability to 0.56+/-0.04 of the control in the absence of noble gas (pnoble gas argon may have potential as a neuroprotectant for the future.

  14. The interpretation of ellipsometric measurements of ion bombardment of noble gases on semiconductor surfaces

    NARCIS (Netherlands)

    Holtslag, A.H.M.; Slager, U.C.; van Silfhout, Arend


    Low energy noble gas ion bombardment and thermal desorption studies were carried out on Si(111) and analysed, in situ, using spectroscopic ellipsometry. The amorphous layer thickness and implanted noble gas fraction were calculated.

  15. Collisional deactivation of Ba 5d7p (3)D1 by noble gases. (United States)

    Smedley, John E; Coulter, Sarah K; Felton, Edward J; Zomlefer, Kayla S


    Collisional deactivation of the 5d7p (3)D1 state of Ba by noble gases is studied by time- and wavelength-resolved fluorescence techniques. A pulsed, frequency-doubled dye laser at 273.9 nm excites the 5d7p (3)D1 level from the ground state, and fluorescence at 364.1 and 366.6 nm from the 5d7p (3)D1 --> 6s5d (3)D1 and 5d7p (3)D1 --> 6s5d (3)D2 transitions, respectively, is monitored in real time to obtain the deactivation rate constants. At 835 K these rate constants are as follows: He, (1.69 +/- 0.08) x 10(-9) cm(3) s(-1); Ne, (3.93 +/- 0.14) x 10(-10) cm(3) s(-1); Ar, (4.53 +/- 0.15) x 10(-10) cm(3) s(-1); Kr, (4.64 +/- 0.13) x 10(-10) cm(3) s(-1); Xe, (5.59 +/- 0.22) x 10(-10) cm(3) s(-1). From time-resolved 5d7p (3)D1 emission in the absence of noble gas and from the intercepts of the quenching plots, the lifetime of this state is determined to be 100 +/- 1 ns. Using time- and wavelength-resolved Ba emission with a low background pressure of noble gas, radiative lifetimes of several near-resonant states are determined from the exponential rise of the fluorescence signals. These results are as follows: 5d6d (3)D3, 28 +/- 3 ns; 5d7p (3)P1, 46 +/- 2 ns; 5d6d (3)G3, 21.5 +/- 0.8 ns; 5d7p (3)F3, 48 +/- 1 ns. Integrated fluorescence signals are used to infer the relative rate constants for population transfer from the 5d7p (3)D1 state to eleven near-resonant fine structure states.

  16. The Role of Noble Gases in Defining the Mean Residence Times of Fluids within Precambrian Crustal Systems (United States)

    Warr, O.; Sherwood Lollar, B.; Fellowes, J.; Sutcliffe, C. N.; McDermott, J. M.; Holland, G.; Mabry, J.; Ballentine, C. J.


    Brines rich in N2, H2, CH4 and He hosted within Precambrian crustal rocks are known to sustain microbial life [1]. The geological systems containing these brines have the potential to isolate organisms over planetary timescales and so can provide unique insight into the diversity and evolution of terrestrial life [1-3]. Long considered geological outliers, the prevalence of systems containing these ancient, deep fracture waters is only now being revealed. Recent studies demonstrate the Precambrian crust which accounts for ~70% of total crustal surface area has a global hydrogen production comparable to marine systems [2]. In addition to H2-producing reactions (e.g. radiolysis and serpentinization), a diversity of CH4-producing reactions also occur in these systems through both microbial and water-rock interactions [1, 2]. However, the role these Precambrian systems have in global hydrogen and carbon cycles is poorly understood. For this we need good constraints on the origins, residence times and degree of microbial activity of the fluids within these systems as well as the degree of interaction with external systems. Fortunately, noble gases are ideal for this role [1,3]. Previous noble gas analysis of N2, H2, CH4 and He-rich fluid samples collected at 2.4 km depth from a Cu-Zn mine in Timmins, Ontario, identified isolated fracture fluids with the oldest residence times ever observed (>1.1 Ga) [3]. This study has been significantly expanded now to fluids from an even greater depth (3 km) at Timmins, and from two new mines in the Sudbury Basin. Preliminary data from the deeper Timmins level indicate a new closed system with 136Xe/130Xe ratios 93% above modern air values (20% at 2.4 km) and an early atmosphere 124Xe/130Xe signal approaching the age of the host rock (~2.7 Ga) [4]. In comparison, the Sudbury system indicates exchange with an external source, being highly enriched in helium (30% gas volume) but with a low fissiogenic 136Xe/130Xe excess (10-38% above

  17. Optimized Mie potentials for phase equilibria: Application to noble gases and their mixtures with n-alkanes. (United States)

    Mick, Jason R; Soroush Barhaghi, Mohammad; Jackman, Brock; Rushaidat, Kamel; Schwiebert, Loren; Potoff, Jeffrey J


    Transferrable force fields, based on n-6 Mie potentials, are presented for noble gases. By tuning the repulsive exponent, ni, it is possible to simultaneously reproduce experimental saturated liquid densities and vapor pressures with high accuracy, from the normal boiling point to the critical point. Vapor-liquid coexistence curves for pure fluids are calculated using histogram reweighting Monte Carlo simulations in the grand canonical ensemble. For all noble gases, saturated liquid densities and vapor pressures are reproduced to within 1% and 4% of experiment, respectively. Radial distribution functions, extracted from NVT and NPT Monte Carlo simulations, are in similarly excellent agreement with experimental data. The transferability of the optimized force fields is assessed through calculations of binary mixture vapor-liquid equilibria. These mixtures include argon + krypton, krypton + xenon, methane + krypton, methane + xenon, krypton + ethane, and xenon + ethane. For all mixtures, excellent agreement with experiment is achieved without the introduction of any binary interaction parameters or multi-body interactions.

  18. Evaluation of various planar gaseous detectors with Cs1 photocathodes for the detection of primary scintillation light from noble gases

    CERN Document Server

    Periale, L; Carlson, Per J; Iacobaeus, C; Francke, T; Pavlopoulos, N; Pietropaoplo, F; Sokolova, T; Picchi, P


    Noble gases and liquids are excellent scintillators and this opens a unique opportunity to directly detect the primary scintillation light produced in these media by photons or particles. This signal can be used for several purposes, for example as a start signal for TPCs or for particle's identification. Usually photomultipliers (PMs) are used for the detection of the scintillation light. In our previous work we have demonstrated that costly PMs could be replaced by gaseous detectors with CsI photocathodes. Such detectors have the same quantum efficiency as the best PMs but at the same time are cheap, simple and have high position and time resolutions. The aim of this work is to evaluate various planar type gaseous detectors with CsI photocathodes in order to choose the best one for the detection of the primary scintillation light from noble gases and liquids. (10 refs).

  19. Analytical equation of state with three-body forces: application to noble gases. (United States)

    del Río, Fernando; Díaz-Herrera, Enrique; Guzmán, Orlando; Moreno-Razo, José Antonio; Ramos, J Eloy


    We developed an explicit equation of state (EOS) for small non polar molecules by means of an effective two-body potential. The average effect of three-body forces was incorporated as a perturbation, which results in rescaled values for the parameters of the two-body potential. These values replace the original ones in the EOS corresponding to the two-body interaction. We applied this procedure to the heavier noble gases and used a modified Kihara function with an effective Axilrod-Teller-Muto (ATM) term to represent the two- and three-body forces. We also performed molecular dynamics simulations with two- and three-body forces. There was good agreement between predicted, simulated, and experimental thermodynamic properties of neon, argon, krypton, and xenon, up to twice the critical density and up to five times the critical temperature. In order to achieve 1% accuracy of the pressure at liquid densities, the EOS must incorporate the effect of ATM forces. The ATM factor in the rescaled two-body energy is most important at temperatures around and lower than the critical one. Nonetheless, the rescaling of two-body diameter cannot be neglected at liquid-like densities even at high temperature. This methodology can be extended straightforwardly to deal with other two- and three-body potentials. It could also be used for other nonpolar substances where a spherical two-body potential is still a reasonable coarse-grain approximation.

  20. The noble gases adsorption on boron-rich boron nitride nanotubes: A theoretical investigation (United States)

    Wang, Chong; Guo, Chen


    In this work, using density functional theory (DFT) calculations, we have systematically explored the noble gases (Ng = He, Ne, Ar, Kr) adsorption on boron-rich boron nitride nanotubes (BNNTs) surface with antisite boron atom. One or two nitrogen atoms of BNNTs are replaced by boron atoms, which are considered as boron-rich BNNTs for Ng adsorption. It is found that the boron-rich BNNTs can adsorb Ng in exothermic process, and the adsorption energies increase in order from He to Kr. The quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCIs) calculations show that the interactions between boron-rich BNNTs and Ng are noncovalent, and the interactions for Ar and Kr are obviously larger than those for He and Ne. The charge transfer from Ng to boron-rich BNNTs and the changes of energy gap caused by Ng adsorption demonstrate that the boron-rich BNNTs are expected to become the Ng adsorption and sensing materials. Moreover, the 2B-BNNTs do not decrease the Ng adsorption interactions on boron-rich BNNTs, compared with 1B-BNNTs. It is expected that the present results will provide a useful guide to develop novel boron nitride nanomaterials for storage and application of Ng.

  1. Shock Compression Response of the Light Noble Gases: Neon and Helium (United States)

    Root, Seth; Shulenburger, Luke; Cochrane, Kyle; Lopez, Andrew; Shelton, Keegan; Villalva, Jose; Mattsson, Thomas


    Understanding material behavior at extreme conditions is important to a wide range of processes in planetary astrophysics and inertial confinement fusion. Modeling the high pressure - high temperature processes requires robust equations of state (EOS). For many materials, EOS models have been developed using low-pressure Hugoniot data. Assumptions are made to extrapolate the EOS models to Mbar pressure regimes, leading to different model behavior at extreme conditions. In this work, we examine the high pressure response of the light noble gases: neon and helium in the multi-Mbar regime. We perform a series of shock compression experiments using Sandia's Z-Machine on cryogenically cooled liquids of Ne (26 K) and He (2.2 K) to measure the Hugoniot and reshock states. In parallel, we use density functional theory methods to calculate the Hugoniot and reshock states. The experiments validated the DFT simulations and the combined experimental and simulation results are used to assess the EOS models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

  2. What CO2 well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere. (United States)

    Ballentine, Chris J; Holland, Greg


    Study of commercially produced volcanic CO2 gas associated with the Colorado Plateau, USA, has revealed substantial new information about the noble gas isotopic composition and elemental abundance pattern of the mantle. Combined with published data from mid-ocean ridge basalts, it is now clear that the convecting mantle has a maximum (20)Ne/(22)Ne isotopic composition, indistinguishable from that attributed to solar wind-implanted (SWI) neon in meteorites. This is distinct from the higher (20)Ne/(22)Ne isotopic value expected for solar nebula gases. The non-radiogenic xenon isotopic composition of the well gases shows that 20 per cent of the mantle Xe is 'solar-like' in origin, but cannot resolve the small isotopic difference between the trapped meteorite 'Q'-component and solar Xe. The mantle primordial (20)Ne/(132)Xe is approximately 1400 and is comparable with the upper end of that observed in meteorites. Previous work using the terrestrial (129)I - (129)Xe mass balance demands that almost 99 per cent of the Xe (and therefore other noble gases) has been lost from the accreting solids and that Pu-I closure age models have shown this to have occurred in the first ca 100Ma of the Earth's history. The highest concentrations of Q-Xe and solar wind-implanted (SWI)-Ne measured in meteorites allow for this loss and these high-abundance samples have a Ne/Xe ratio range compatible with the 'recycled-air-corrected' terrestrial mantle. These observations do not support models in which the terrestrial mantle acquired its volatiles from the primary capture of solar nebula gases and, in turn, strongly suggest that the primary terrestrial atmosphere, before isotopic fractionation, is most probably derived from degassed trapped volatiles in accreting material.By contrast, the non-radiogenic argon, krypton and 80 per cent of the xenon in the convecting mantle have the same isotopic composition and elemental abundance pattern as that found in seawater with a small sedimentary Kr

  3. Noble gases preserve history of retentive continental crust in the Bravo Dome natural CO2 field, New Mexico (United States)

    Sathaye, Kiran J.; Smye, Andrew J.; Jordan, Jacob S.; Hesse, Marc A.


    Budgets of 4He and 40Ar provide constraints on the chemical evolution of the solid Earth and atmosphere. Although continental crust accounts for the majority of 4He and 40Ar degassed from the Earth, degassing mechanisms are subject to scholarly debate. Here we provide a constraint on crustal degassing by comparing the noble gases accumulated in the Bravo Dome natural CO2 reservoir, New Mexico USA, with the radiogenic production in the underlying crust. A detailed geological model of the reservoir is used to provide absolute abundances and geostatistical uncertainty of 4He, 40Ar, 21Ne, 20Ne, 36Ar, and 84Kr. The present-day production rate of crustal radiogenic 4He and 40Ar, henceforth referred to as 4He* and 40Ar*, is estimated using the basement composition, surface and mantle heat flow, and seismic estimates of crustal density. After subtracting mantle and atmospheric contributions, the reservoir contains less than 0.02% of the radiogenic production in the underlying crust. This shows unequivocally that radiogenic noble gases are effectively retained in cratonic continental crust over millennial timescales. This also requires that approximately 1.5 Gt of mantle derived CO2 migrated through the crust without mobilizing the crustally accumulated gases. This observation suggests transport along a localized fracture network. Therefore, the retention of noble gases in stable crystalline continental crust allows shallow accumulations of radiogenic gases to record tectonic history. At Bravo Dome, the crustal 4He*/40Ar* ratio is one fifth of the expected crustal production ratio, recording the preferential release of 4He during the Ancestral Rocky Mountain orogeny, 300 Ma.

  4. Nitrogen and noble gases in a glass sample from LEW88516 (United States)

    Becker, R. H.; Pepin, R. O.


    The Antarctic meteorite LEW88516 has been classified as a member of the SNC group of meteorites, specifically a shergottite. It is reported to be remarkably similar in mineralogy, petrogenesis and chemistry to the previously known ALH77005 shergottite, with both being compositionally distinct from other shergottites. LEW88516 shows pervasive shock features and has been found to contain glass veins attributable to a shock origin. In an effort to determine whether the glass in LEW88516 contains any of the isotopically-heavy trapped nitrogen component observed in EETA 79001 glass, as well as the related high-Ar-40/Ar-36 and high-Xe-129/Xe-132 components, we undertook an analysis of an 11.9 mg glass sample (LEW88516,4) provided to us by H. Y. McSween, Jr. as part of a consortium study of this meteorite. Nitrogen and noble gases were extracted from LEW88516,4 in a series of combustion steps at increasing temperatures followed by a final pyrolysis. Initial steps at 550 C were intended to remove any surface-sited nitrogen-containing contaminants, while the 700 C step was expected to show the onset of release of a trapped argon component, based on our previous data for EETA 79001. It was hoped that the bulk of any trapped gas release would be concentrated in one of two steps at 1100 C and approximately 1400 C, maximizing our analytical sensitivity. Results of the analysis are shown. Except for He and Ne, data obtained for the 550 C steps will be omitted from further consideration on the assumption that they represent terrestrial contamination.

  5. Extraction of Solar Wind Nitrogen and Noble Gases From the Genesis Gold Foil Collector (United States)

    Schlutter, D. J.; Pepin, R. O.


    The Genesis gold foil is a bulk solar wind collector, integrating fluences from all three of the wind regimes. Pyrolytic extraction of small foil samples at Minnesota yielded He fluences, corrected for backscatter, in good agreement with measurements by on-board spacecraft instruments, and He/Ne elemental ratios close to those implanted in collector foils deployed on the lunar surface during the Apollo missions. Isotopic distributions of He, Ne and Ar are under study. Pyrolysis to temperatures above the gold melting point generates nitrogen blanks large enough to obscure the solar-wind nitrogen component. An alternative technique for nitrogen and noble gas extraction, by room-temperature amalgamation of the gold foil surface, will be discussed. Ne and Ar releases in preliminary tests of this technique on small foil samples were close to 100% of the amounts expected from the high-temperature pyrolysis yields, indicating that amalgamation quantitatively liberates gases from several hundred angstroms deep in the gold, beyond the implantation depth of most of the solar wind. Present work is focused on two problems currently interfering with accurate nitrogen measurements at the required picogram to sub-picogram levels: a higher than expected blank likely due to tiny air bubbles rolled into the gold sheet during fabrication, and the presence of a refractory hydrocarbon film on Genesis collector surfaces (the "brown stain") that, if left in place on the foil, shields the underlying gold from mercury attack. We have found, however, that the film is efficiently removed within tens of seconds by oxygen plasma ashing. Potential nitrogen contaminants introduced during the crash of the sample return canister are inert in amalgamation, and so are not hazards to the measurements.

  6. Mean ocean temperature change over the last glacial transition based on heavy noble gases in the atmosphere (United States)

    Bereiter, Bernhard; Severinghaus, Jeff; Shackleton, Sarah; Baggenstos, Daniel; Kawamura, Kenji


    On paleo-climatic timescales heavy noble gases (krypton and xenon) are conserved in the atmosphere-ocean system and are passively cycled through this system without interaction with any biogeochemical process. Due to the characteristic temperature dependency of the gas solubility factors in sea water, the atmospheric noble gas content is unambiguously linked to mean global ocean temperature (MOT). Here we use this proxy to reconstruct MOT over the course of the last glacial transition based on measurements of trapped air in the WAIS Divide ice core. We analyzed 78 ice samples with a recently developed method that yields the isotopic ratios of N2, Ar, Kr and the elemental ratios of Kr/N2, Xe/N2 and Xe/Kr in the trapped air with the required precision. Based on the isotopic ratios we correct the elemental ratios for the fractionation processes in the firn column to obtain the true atmospheric values. On the basis of a 4-box model that incorporates effects of sea-level change, different saturation states of the water and different temperature distributions in the global ocean, we infer MOT based on the three elemental ratio pairs and assess its uncertainty. On average, the uncertainty of our MOT record is +/- 0.27°C, which is a significant improvement to earlier studies that reached about +/- 1°C uncertainty. This allows an unprecedented assessment of the glacial-interglacial MOT difference, as well as a direct comparison between MOT and climate change for the first time. We find a LGM-Holocene difference of 2.6°C, which is on the lower end of what earlier studies have suggested (3 +/- 1°C) and provides a new constraint on ocean heat uptake over the last glacial transition. Furthermore, we find a very close relation between MOT and Antarctic temperatures which shows for the first time the effect of Atlantic overturning circulation changes on global ocean heat uptake. Finally, our record shows a MOT warming rate during the Younger Dryas that is almost double to

  7. Tracing ancient hydrogeological fracture network age and compartmentalisation using noble gases (United States)

    Warr, Oliver; Sherwood Lollar, Barbara; Fellowes, Jonathan; Sutcliffe, Chelsea N.; McDermott, Jill M.; Holland, Greg; Mabry, Jennifer C.; Ballentine, Christopher J.


    We show that fluid volumes residing within the Precambrian crystalline basement account for ca 30% of the total groundwater inventory of the Earth (> 30 million km3). The residence times and scientific importance of this groundwater are only now receiving attention with ancient fracture fluids identified in Canada and South Africa showing: (1) microbial life which has existed in isolation for millions of years; (2) significant hydrogen and hydrocarbon production via water-rock reactions; and (3) preserving noble gas components from the early atmosphere. Noble gas (He, Ne, Ar, Kr, Xe) abundance and isotopic compositions provide the primary evidence for fluid mean residence time (MRT). Here we extend the noble gas data from the Kidd Creek Mine in Timmins Ontario Canada, a volcanogenic massive sulfide (VMS) deposit formed at 2.7 Ga, in which fracture fluids with MRTs of 1.1-1.7 Ga were identified at 2.4 km depth (Holland et al., 2013); to fracture fluids at 2.9 km depth. We compare here the Kidd Creek Mine study with noble gas compositions determined in fracture fluids taken from two mines (Mine 1 & Mine 2) at 1.7 and 1.4 km depth below surface in the Sudbury Basin formed by a meteorite impact at 1.849 Ga. The 2.9 km samples at Kidd Creek Mine show the highest radiogenic isotopic ratios observed to date in free fluids (e.g. 21Ne/22Ne = 0.6 and 40Ar/36Ar = 102,000) and have MRTs of 1.0-2.2 Ga. In contrast, resampled 2.4 km fluids indicated a less ancient MRT (0.2-0.6 Ga) compared with the previous study (1.1-1.7 Ga). This is consistent with a change in the age distribution of fluids feeding the fractures as they drain, with a decreasing proportion of the most ancient end-member fluids. 129Xe/136Xe ratios for these fluids confirm that boreholes at 2.4 km versus 2.9 km are sourced from hydrogeologically distinct systems. In contrast, results for the Sudbury mines have MRTs of 0.2-0.6 and 0.2-0.9 Ga for Mines 1 and 2 respectively. While still old compared to almost all

  8. H3(+) as a trap for noble gases-3: multiple trapping of neon, argon, and krypton in X(n)H3(+) (n = 1-3). (United States)

    Pauzat, F; Ellinger, Y; Pilmé, J; Mousis, O


    Recent studies on the formation of XH(3)(+) noble gas complexes have shown strategic implications for the composition of the atmospheres of the giant planets as well as for the composition of comets. One crucial factor in the astrophysical process is the relative abundances of the noble gases versus H(3)(+). It is the context in which the possibility for clustering with more than one noble gas (X(n)H(3)(+) up to n = 3) has been investigated for noble gases X ranging from neon to krypton. In order to assert our results, a variety of methods have been used including ab initio coupled cluster CCSD and CCSD(T), MP2, and density functional BH&HLYP levels of theory. All complexes with one, two, and three noble gases are found to be stable in the Ne, Ar, and Kr families. These stable structures are planar with the noble gases attached to the apices of the H(3)(+) triangle. The binding energy of the nth atom, defined as the X(n)H(3)(+) --> X(n-1)H(3)(+) + X reaction energy, increases slightly with n varying from 1 to 3 in the neon series, while it decreases in the argon series and shows a minimum for n = 2 in the krypton series. The origin of this phenomenon is to be found in the variations in the respective vibrational energies. A topological analysis of the electron localization function shows the importance of the charge transfer from the noble gases toward H(3)(+) as a driving force in the bonding along the series. It is also consistent with the increase in the atomic polarizabilities from neon to krypton. Rotational constants and harmonic frequencies are reported in order to provide a body of data to be used for the detection in laboratory prior to space observations. This study strongly suggests that the noble gases could be sequestered even in an environment where the H(3)(+) abundance is small.

  9. Noble gases in submarine pillow basalt glasses from Loihi and Kilauea, Hawaii: A solar component in the Earth (United States)

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.


    Noble gas elemental and isotopic abundances have been analysed in twenty-two samples of basaltic glass dredged from the submarine flanks of two currently active Hawaiian volcanoes, Loihi Seamount and Kilauea. Neon isotopic ratios are enriched in 20Ne and 21Ne by as much as 16% with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high 3He 4He ratios. The high 20Ne 22Ne values in some of the Hawaiian samples, together with correlations between neon and helium systematics, suggest the presence of a solar component in the source regions of the Hawaiian mantle plume. The solar hypothesis for the Earth's primordial noble gas composition can account for helium and neon isotopic ratios observed in basaltic glasses from both plume and spreading systems, in fluids in continental hydrothermal systems, in CO2 well gases, and in ancient diamonds. These results provide new insights into the origin and evolution of the Earth's atmosphere. ?? 1993.

  10. A comprehensive study of noble gases and nitrogen in "Hypatia", a diamond-rich pebble from SW Egypt (United States)

    Avice, Guillaume; Meier, Matthias M. M.; Marty, Bernard; Wieler, Rainer; Kramers, Jan D.; Langenhorst, Falko; Cartigny, Pierre; Maden, Colin; Zimmermann, Laurent; Andreoli, Marco A. G.


    This is a follow-up study of a work by Kramers et al. (2013) on a very unusual diamond-rich rock fragment found in the area of south west Egypt in the south-western side of the Libyan Desert Glass strewn field. This pebble, called Hypatia, is composed of almost pure carbon. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) results reveal that Hypatia is mainly made of defect-rich diamond containing lonsdaleite and multiple deformation bands. These characteristics are compatible with an impact origin on Earth and/or in space. We also analyzed concentrations and isotopic compositions of all five noble gases and nitrogen in several ∼mg sized Hypatia samples. These data confirm the conclusion by Kramers et al. (2013) that Hypatia is extra-terrestrial. The sample is relatively rich in trapped noble gases with an isotopic composition being close to the Q component found in many types of meteorites. 40Ar/36Ar ratios in individual steps are as low as 0.4 ± 0.3. Cosmic-ray produced ;cosmogenic; 21Ne is present in concentrations corresponding to a nominal cosmic-ray exposure (CRE) age of roughly 0.1 Myr if produced in a typical meter-sized meteoroid. Such an atypically low nominal CRE age suggests high shielding in a considerably larger body. In addition to the Xe-Q composition, an excess of radiogenic 129Xe (from the decay of short-lived radioactive 129I) is observed (129Xe /132Xe = 1.18 + / - 0.03). Two isotopically distinct N components are present, an isotopically heavy component (δ15N ∼ + 20 ‰) released at low temperatures and a major isotopically light component (δ15N ∼ - 110 ‰) at higher temperatures. This disequilibrium in N suggests that the diamonds in Hypatia were formed in space rather than upon impact on Earth (δN15atm = 0 ‰). All our data are broadly consistent with concentrations and isotopic compositions of noble gases in at least three different types of carbon-rich meteoritic materials: carbon-rich veins in ureilites

  11. Elliptical polarization favors long quantum orbits in high-order above-threshold ionization of noble gases. (United States)

    Lai, XuanYang; Wang, ChuanLiang; Chen, YongJu; Hu, ZiLong; Quan, Wei; Liu, XiaoJun; Chen, Jing; Cheng, Ya; Xu, ZhiZhan; Becker, Wilhelm


    We demonstrate the significant role of long quantum orbits in strong-field atomic processes by investigating experimentally and theoretically the above-threshold ionization spectra of noble gases in intense elliptically polarized laser pulses. With increasing laser ellipticity, the yields of different energy regions of the measured electron spectrum in high-order above-threshold ionization drop at different rates. The experimental features can be reproduced by a theoretical simulation based on quantum-orbit theory, revealing that increasing ellipticity favors the contributions of the long quantum orbits in the high-order above-threshold ionization process.

  12. Noble metal-free hydrogen evolution catalysts for water splitting. (United States)

    Zou, Xiaoxin; Zhang, Yu


    Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource-derived electricity and direct solar-to-hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal-free hydrogen evolution catalysts to make the water splitting process more energy-efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal-free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER). We review several important kinds of heterogeneous non-precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom-doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition-catalytic activity relationship. We also summarize some important examples showing that non-Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar-to-hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.

  13. Implications of noble gases in a recently recognized Martian meteorite (ALH84001) for the degassing history of Mars (United States)

    Swindle, T. D.


    For terrestrial planets, atmospheric compositions are not static, but evolve with time, in part due to degassing of the interior. Unfortunately, the evolution is slow enough that it is usually not observable on human timescales, or even on the timescales of rocks that preserve samples of Earth's ancient atmosphere. Preliminary results on a recently recognized Martian meteorite, ALH84001, indicate that it is a very old rock, and has a relatively high noble gas content suggestive of atmospheric incorporation, but with an isotopic composition slightly inconsistent with currently known Martian reservoirs. Hence, this rock may provide a sample of ancient Martian atmosphere, which can be used to test models of volatile evolution (in particular, degassing) on Mars. ALH84001 is a cumulate orthopyroxenite. Although originally classified as a diogenite, its oxygen isotopes, and several chemical and petrographic features, strong suggest that it is, like the SNC meteorites, Martian. A Sm-Nd crystallization age of 4.5 Ga has been reported. The meteorite is rich in noble gases, compared to most SNC's. In many respects the noble gases are typical of SNC meteorites. However, there are some subtle differences. In particular, the Xe isotopes in SNC meteorites can be explained as a mixture of Martian atmospheric Xe (as represented by glass in EETA 79001), the Xe in the dunite Chassigny (usually assumed to be representative of the Martian interior, and with lower (129)Xe/(132)Xe, (134)Xe/(132)Xe and (136)Xe/(132)Xe ratios), and later additions from known processes like fission, spallation and terrestrial contamination. The isotopic composition of ALH84001 is inconsistent (at greater than 2-3 sigma) with any mixture of those components. Even if no accumulation of fission Xe during the age of the rock is assumed, there is too little (136)Xe and (134)Xe for the amount of (129)Xe measured.

  14. Emission of fast hydrogen atoms at a plasma–solid interface in a low density plasma containing noble gases (United States)

    Marchuk, O.; Brandt, C.; Pospieszczyk, A.; Reinhart, M.; Brezinsek, S.; Unterberg, B.; Dickheuer, S.


    The source of the broad radiation of fast hydrogen atoms in plasmas containing noble gases remains one of the most discussed problems relating to plasma–solid interface. In this paper, we present a detailed study of Balmer lines emission generated by fast hydrogen and deuterium atoms in an energy range between 40 and 300 eV in a linear magnetised plasma. The experiments were performed in gas mixtures containing hydrogen or deuterium and one of the noble gases (He, Ne, Ar, Kr or Xe). In the low-pressure regime (0.01–0.1 Pa) of plasma operation emission is detected by using high spectral and spatial resolution spectrometers at different lines-of-sight for different target materials (C, Fe, Rh, Pd, Ag and W). We observed the spatial evolution for H α , H β and H γ lines with a resolution of 50 μm in front of the targets, proving that emission is induced by reflected atoms only. The strongest radiation of fast atoms was observed in the case of Ar–D or Ar–H discharges. It is a factor of five less in Kr–D plasma and an order of magnitude less in other rare gas mixture plasmas. First, the present work shows that the maximum of emission is achieved for the kinetic energy of 70–120 eV/amu of fast atoms. Second, the emission profile depends on the target material as well as surface characteristics such as the particle reflection, e.g. angular and energy distribution, and the photon reflectivity. Finally, the source of emission of fast atoms is narrowed down to two processes: excitation caused by collisions with noble gas atoms in the ground state, and excitation transfer between the metastable levels of argon and the excited levels of hydrogen or deuterium.

  15. The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory. (United States)

    Ottonello, Giulio; Richet, Pascal


    The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ɛ) of the investigated silicate melts and its optical counterpart (ɛ(∞)) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter σs, along the guidelines already used in the past for simple media such as water or benzene. The σs obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25 °C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of

  16. The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory (United States)

    Ottonello, Giulio; Richet, Pascal


    The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ɛ) of the investigated silicate melts and its optical counterpart (ɛ∞) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter σs, along the guidelines already used in the past for simple media such as water or benzene. The σs obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25 °C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of

  17. Laboratory shock emplacement of noble gases, nitrogen, and carbon dioxide into basalt, and implications for trapped gases in shergottite EETA 79001 (United States)

    Wiens, R. C.; Pepin, R. O.


    Basalts from the Servilleta flows, Taos, NM, described by Lofgren (1983) were analyzed by mass spectrometry for shock-implanted noble gases, N2, and CO2 (which were isotopically labeled) after an exposure to 20-60 GPa shock in the presence of 0.0045-3.0 atm of ambient gas. The results were compared with data available on the constituents of the EETA 79001 meteorite. As expected, the samples shocked in this study attained emplacement efficiencies significantly lower than those apparent for lithology C of EETA 79001. Possible explanations for this difference include atmospheric overpressure at the time of EETA 79001 exposure to shock, the trapping of gas already in vugs by the intruding melt material, or the collapse of gas-filled vugs to form gas-laden glass inclusions.

  18. Cosmogenic Records in 18 Ordinary Chondrites from the Dar Al Gani Region, Libya. 1; Noble Gases (United States)

    Schultz, L.; Franke, L.; Welten, K. C.; Nishiizumi, K.; Jull, A. J. T.


    In the last decade thousands of meteorites have been recovered from hot deserts in the Sahara and Oman. One of the main meteorite concentration surfaces in the Sahara is the Dar al Gani plateau in Libya, which covers a total area of 8000 km2. More than 1000 meteorites have been reported from this area. The geological setting, meteorite pairings and the meteorite density of the Dar al Gani (DaG) field are described in more detail in [1]. In this work we report concentrations of the noble gas isotopes of He, Ne, Ar as well as 84Kr and 132Xe in 18 DaG meteorites. In a separate paper we will report the cosmogenic radionuclides [2]. We discuss the thermal history and cosmic-ray exposure (CRE) history of these meteorites, and evaluate the effects of the hot desert environment on the noble gas record.

  19. The application of noble metals in light-water reactors (United States)

    Kim, Young-Jin; Niedrach, Leonard W.; Indig, Maurice E.; Andresen, Peter L.


    Corrosion potential is a primary determinant of the stress-corrosion cracking susceptibility of structural materials in high-temperature water. Efforts to minimize stress-corrosion cracking in light-water reactors include adding hydrogen. In someplants' out-of-core regions, the hydrogen required to achieve the desired corrosion potential is relatively high. In-core, more hydrogen is needed for an equivalent reduction in corrosion potential. Additionally, sIDe effects of high hydrogen-addition rates, including increased 16N turbine shine and 60CO deposition, have also been observed in some cases. An approach involving noble-metal coatings on and alloying additions to engineering materials dramatically improves the efficiency with which the corrosion potential is decreased as a function of hydrogen addition, such that very low potentials are obtained once a stoichiometric concentration of hydrogen (versus oxygen) is achieved.

  20. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    Directory of Open Access Journals (Sweden)

    X. H. Liu


    Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  1. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites (United States)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.


    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  2. Silicon PIN diode based electron-gamma coincidence detector system for Noble Gases monitoring. (United States)

    Khrustalev, K; Popov, V Yu; Popov, Yu S


    We present a new second generation SiPIN based electron-photon coincidence detector system developed by Lares Ltd. for use in the Noble Gas measurement systems of the International Monitoring System and the On-site Inspection verification regimes of the Comprehensive Nuclear-Test Ban Treaty (CTBT). The SiPIN provide superior energy resolution for electrons. Our work describes the improvements made in the second generation detector cells and the potential use of such detector systems for other applications such as In-Situ Kr-85 measurements for non-proliferation purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Elimination of gases and contamination from water (United States)

    Buck, A. P.


    Filtration system with membrane type hydrophilic and hydrophobic filters gives absolute filtration with automatic venting of freed gases, and prevents backward transmission of contamination with no bacterial growth through the filters. Filter aids in degassing industrial solutions and in removing oxygen from sea water.

  4. MRI of the lung gas-space at very low-field using hyperpolarized noble gases (United States)

    Venkatesh, Arvind K.; Zhang, Adelaide X.; Mansour, Joey; Kubatina, Lyubov; Oh, Chang Hyun; Blasche, Gregory; Selim Unlu, M.; Balamore, Dilip; Jolesz, Ferenc A.; Goldberg, Bennett B.; hide


    In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static magnetic field (B(0)), making very low-field (VLF) MRI possible; indeed, it is possible to contemplate portable MRI using light-weight solenoids or permanent magnets. This article reports the first in vivo VLF MR images of the lungs in humans and in rats, obtained at a field of only 15 millitesla (150 Gauss).

  5. Photo-Ionization of Noble Gases: A Demonstration of Hybrid Coupled Channels Approach

    Directory of Open Access Journals (Sweden)

    Vinay Pramod Majety


    Full Text Available We present here an application of the recently developed hybrid coupled channels approach to study photo-ionization of noble gas atoms: Neon and Argon. We first compute multi-photon ionization rates and cross-sections for these inert gas atoms with our approach and compare them with reliable data available from R-matrix Floquet theory. The good agreement between coupled channels and R-matrix Floquet theory show that our method treats multi-electron systems on par with the well established R-matrix theory. We then apply the time dependent surface flux (tSURFF method with our approach to compute total and angle resolved photo-electron spectra from Argon with linearly and circularly polarized 12 nm wavelength laser fields, a typical wavelength available from Free Electron Lasers (FELs.

  6. Simulating mesoscale transport and diffusion of radioactive noble gases using the Lagrangian particle dispersion model. (United States)

    Kim, Cheol-Hee; Song, Chang-Keun; Lee, Sang-Hyun; Song, Sang-Keun


    In order to simulate the impact of mesoscale wind fields and to assess potential capability of atmospheric Lagrangian particle dispersion model (LPDM) as an emergency response model for the decision supports, two different simulations of LPDM with the mesoscale prognostic model MM5 (Mesoscale Model ver. 5) were driven. The first simulation of radioactive noble gas (85Kr exponent) emitted during JCO accident occurred from 30 September to 3 October 1999 at Tokai, Japan showed that the first arriving short pulse was found in Tsukuba located at 60 km away from the accidental area. However, the released radioactive noble gas was transported back to the origin site about 2 days later due to the mesoscale meteorological wind circulation, enhancing the levels of 85Kr with the secondary peak in Tsukuba. The second simulation of atmospheric dilution factors (the ratio of concentration to the emission rate, chi/Q), during the underground nuclear test (UNT) performed by North Korea showed that high chi/Q moved to the eastward and extended toward southward in accordance with the mesoscale atmospheric circulations generated by mesoscale prognostic model MM5. In comparison with the measurements, the simulated horizontal distribution patterns of 85Kr during the JCO are well accord with that of observation in Tsukuba such as the existence of secondary peak which is associated with the mesoscale circulations. However, the simulated level of 85Kr anomaly was found to be significantly lower than the observations, and some interpretations on these discrepancies were described. Applications of LPDM to two mesoscale emergency response dispersion cases suggest the potential capability of LPDM to be used as a decision support model provided accurate emission rate of accident in case of a large accident.

  7. Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A. (United States)

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.


    Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

  8. Sedimentary halogens and noble gases within Western Antarctic xenoliths: Implications of extensive volatile recycling to the sub continental lithospheric mantle (United States)

    Broadley, Michael W.; Ballentine, Chris J.; Chavrit, Déborah; Dallai, Luigi; Burgess, Ray


    Recycling of marine volatiles back into the mantle at subduction zones has a profound, yet poorly constrained impact on the geochemical evolution of the Earth's mantle. Here we present a combined noble gas and halogen study on mantle xenoliths from the Western Antarctic Rift System (WARS) to better understand the flux of subducted volatiles to the sub continental lithospheric mantle (SCLM) and assess the impact this has on mantle chemistry. The xenoliths are extremely enriched in the heavy halogens (Br and I), with I concentrations up to 1 ppm and maximum measured I/Cl ratios (85.2 × 10-3) being ∼2000 times greater than mid ocean ridge basalts (MORB). The Br/Cl and I/Cl ratios of the xenoliths span a range from MORB-like ratios to values similar to marine pore fluids and serpentinites, whilst the 84Kr/36Ar and 130Xe/36Ar ratios range from modern atmosphere to oceanic sediments. This indicates that marine derived volatiles have been incorporated into the SCLM during an episode of subduction related metasomatism. Helium isotopic analysis of the xenoliths show average 3He/4He ratios of 7.5 ± 0.5 RA (where RA is the 3He/4He ratio of air = 1.39 × 10-6), similar to that of MORB. The 3He/4He ratios within the xenoliths are higher than expected for the xenoliths originating from the SCLM which has been extensively modified by the addition of subducted volatiles, indicating that the SCLM beneath the WARS must have seen a secondary alteration from the infiltration and rise of asthenospheric fluids/melts as a consequence of rifting and lithospheric thinning. Noble gases and halogens within these xenoliths have recorded past episodes of volatile interaction within the SCLM and can be used to reconstruct a tectonic history of the WARS. Marine halogen and noble gas signatures within the SCLM xenoliths provide evidence for the introduction and retention of recycled volatiles within the SCLM by subduction related metasomatism, signifying that not all volatiles that survive

  9. Relativistic contributions to single and double core electron ionization energies of noble gases. (United States)

    Niskanen, J; Norman, P; Aksela, H; Agren, H


    We have performed relativistic calculations of single and double core 1s hole states of the noble gas atoms in order to explore the relativistic corrections and their additivity to the ionization potentials. Our study unravels the interplay of progression of relaxation, dominating in the single and double ionization potentials of the light elements, versus relativistic one-electron effects and quantum electrodynamic effects, which dominate toward the heavy end. The degree of direct relative additivity of the relativistic corrections for the single electron ionization potentials to the double electron ionization potentials is found to gradually improve toward the heavy elements. The Dirac-Coulomb Hamiltonian is found to predict a scaling ratio of ∼4 for the relaxation induced relativistic energies between double and single ionization. Z-scaling of the computed quantities were obtained by fitting to power law. The effects of nuclear size and form were also investigated and found to be small. The results indicate that accurate predictions of double core hole ionization potentials can now be made for elements across the full periodic table.

  10. Production Rates of Noble Gases in the Near-Surface Layers of Europa by Energetic Charged Particles and the Potential for Determining Exposure Ages (United States)

    Swindle, T. D.; Reedy, R. C.; Masarik, J.


    The surface of Europa is expected to be extremely active, undergoing tectonic and/or tidal geological activity and sputtering/ deposition, as well as impact cratering. Determination of the actual age of the surface at one or more places would greatly simplify trying to sort out what processes are occurring, and at what rate. If there is K present, as the spectral and compositional modeling discussed predict, it should be possible, in principle, to determine K-Ar crystallization ages. Whether or not there is K present, a consideration of the environment suggests we can determine an energetic particle exposure age if we can make in situ measurements of the abundances of major elements and of noble gas isotopes. This requires instrumentation that is within reach of current technology. In this paper, we calculate production rates for noble-gas isotopes in a simplified Europan surface, to quantify the amount of light noble gases produced by exposure to energetic particles.

  11. Gradient-induced longitudinal relaxation of hyperpolarized noble gases in the fringe fields of superconducting magnets used for magnetic resonance. (United States)

    Zheng, Wangzhi; Cleveland, Zackary I; Möller, Harald E; Driehuys, Bastiaan


    When hyperpolarized noble gases are brought into the bore of a superconducting magnet for magnetic resonance imaging (MRI) or spectroscopy studies, the gases must pass through substantial field gradients, which can cause rapid longitudinal relaxation. In this communication, we present a means of calculating this spatially dependent relaxation rate in the fringe field of typical magnets. We then compare these predictions to experimental measurements of (3)He relaxation at various positions near a medium-bore 2-T small animal MRI system. The calculated and measured relaxation rates on the central axis of the magnet agree well and show a maximum (3)He relaxation rate of 3.83×10(-3) s(-1) (T(1)=4.4 min) at a distance of 47 cm from the magnet isocenter. We also show that if this magnet were self-shielded, its minimum T(1) would drop to 1.2 min. In contrast, a typical self-shielded 1.5-T clinical MRI scanner will induce a minimum on-axis T(1) of 12 min. Additionally, we show that the cylindrically symmetric fields of these magnets enable gradient-induced relaxation to be calculated using only knowledge of the on-axis longitudinal field, which can either be measured directly or calculated from a simple field model. Thus, while most MRI magnets employ complex and proprietary current configurations, we show that their fringe fields and the resulting gradient-induced relaxation are well approximated by simple solenoid models. Finally, our modeling also demonstrates that relaxation rates can increase by nearly an order of magnitude at radial distances equivalent to the solenoid radius. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Evaluation of various planar gaseous detectors with CsI photocathodes for the detection of primary scintillation light from noble gases

    CERN Document Server

    Periale, L; Carlson, P J; Francke, T; Iacobaeus, C; Pavlopoulos, P; Pietropaolo, F; Sokolova, T


    Noble gases and liquids are excellent scintillators and this opens a unique opportunity to directly detect the primary scintillation light produced in these media by photons or particles. This signal can be used for several purposes, for example as a start signal for TPCs or for particles identification. Usually photomultipliers (PMs) are used for the detection of the scintillation light. In our previous work we have demonstrated that costly PMs could be replaced by gaseous detectors with CsI photocathodes . Such detectors have the same quantum efficiency as the best PMs but at the same time are cheap, simple and have high position and time resolutions. The aim of this work is to evaluate various planar type gaseous detectors with CsI photocahodes in order to choose the best one for the detection of the primary scintillation light from noble gases and liquids.

  13. A density functional theory study of magneto-electric Jones birefringence of noble gases, furan homologues, and mono-substituted benzenes. (United States)

    Fahleson, Tobias; Norman, Patrick; Coriani, Sonia; Rizzo, Antonio; Rikken, Geert L J A


    We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analytic linear and nonlinear response functions in the framework of time-dependent density functional theory. A correlation is made between the observable (the Jones constant) and the atomic radius for noble gases, or the permanent electric dipole and a structure/chemical reactivity descriptor as the para Hammett constant for substituted benzenes.

  14. QED effects in 1s and 2s single and double ionization potentials of the noble gases. (United States)

    Niskanen, J; Jänkälä, K; Huttula, M; Föhlisch, A


    We present calculations on the quantum electrodynamics (QED) effects in 1s and 2s single and double ionization potentials of noble gases from Ne to Rn as perturbations on relativistic four-component Dirac-Fock wavefunctions. The most dominant effect originates from the self-energy of the core-electron that yields corrections of similar order as the transverse interaction. For 1s ionization potentials, a match within few eV against the known experimental values is obtained, and our work reveals considerable QED effects in the photoelectron binding energies across the periodic table-most strikingly even for Ne. We perform power-law fits for the corrections as a function of Z and interpolate the QED correction of ∼-0.55 eV for S1s. Due to this, the K-edge electron spectra of the third row and below need QED for a match in the absolute energy when using state-of-the-art instrumentation.

  15. Superelectrophilic Behavior of an Anion Demonstrated by the Spontaneous Binding of Noble Gases to [B12 Cl11 ](). (United States)

    Rohdenburg, Markus; Mayer, Martin; Grellmann, Max; Jenne, Carsten; Borrmann, Tobias; Kleemiss, Florian; Azov, Vladimir A; Asmis, Knut R; Grabowsky, Simon; Warneke, Jonas


    It is common and chemically intuitive to assign cations electrophilic and anions nucleophilic reactivity, respectively. Herein, we demonstrate a striking violation of this concept: The anion [B12 Cl11 ](-) spontaneously binds to the noble gases (Ngs) xenon and krypton at room temperature in a reaction that is typical of "superelectrophilic" dications. [B12 Cl11 Ng](-) adducts, with Ng binding energies of 80 to 100 kJ mol(-1) , contain B-Ng bonds with a substantial degree of covalent interaction. The electrophilic nature of the [B12 Cl11 ](-) anion is confirmed spectroscopically by the observation of a blue shift of the CO stretching mode in the IR spectrum of [B12 Cl11 CO](-) and theoretically by investigation of its electronic structure. The orientation of the electric field at the reactive site of [B12 Cl11 ](-) results in an energy barrier for the approach of polar molecules and facilitates the formation of Ng adducts that are not detected with reactive cations such as [C6 H5 ](+) . This introduces the new chemical concept of "dipole-discriminating electrophilic anions." © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Proton affinities of maingroup-element hydrides and noble gases: trends across the periodic table, structural effects, and DFT validation. (United States)

    Swart, Marcel; Rösler, Ernst; Bickelhaupt, F Matthias


    We have carried out an extensive exploration of the gas-phase basicity of archetypal neutral bases across the periodic system using the generalized gradient approximation (GGA) of the density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton affinities and related thermochemical quantities: BP86/QZ4P//BP86/TZ2P is shown to yield a mean absolute deviation of 2.0 kcal/mol for the proton affinity at 298 K with respect to experiment, and 1.2 kcal/mol with high-level ab initio benchmark data. The main purpose of this work is to provide the proton affinities (and corresponding entropies) at 298 K of the neutral bases constituted by all maingroup-element hydrides of groups 15-17 and the noble gases, that is, group 18, and periods 1-6. We have also studied the effect of step-wise methylation of the protophilic center of the second- and third-period bases. Copyright 2006 Wiley Periodicals, Inc.

  17. QED effects in 1s and 2s single and double ionization potentials of the noble gases (United States)

    Niskanen, J.; Jänkälä, K.; Huttula, M.; Föhlisch, A.


    We present calculations on the quantum electrodynamics (QED) effects in 1s and 2s single and double ionization potentials of noble gases from Ne to Rn as perturbations on relativistic four-component Dirac-Fock wavefunctions. The most dominant effect originates from the self-energy of the core-electron that yields corrections of similar order as the transverse interaction. For 1s ionization potentials, a match within few eV against the known experimental values is obtained, and our work reveals considerable QED effects in the photoelectron binding energies across the periodic table—most strikingly even for Ne. We perform power-law fits for the corrections as a function of Z and interpolate the QED correction of ˜-0.55 eV for S1s. Due to this, the K-edge electron spectra of the third row and below need QED for a match in the absolute energy when using state-of-the-art instrumentation.

  18. Noble gases and halogens in Graves Nunataks 06129: The complex thermal history of a felsic asteroid crust (United States)

    Claydon, Jennifer L.; Crowther, Sarah A.; Fernandes, Vera A.; Gilmour, Jamie D.


    The meteorite Graves Nunataks 06128/06129 is a rare example of felsic asteroidal crust. Knowledge of its history can help shed light on the evolution processes of planetesimals. The noble gases can be used to constrain both the chronology of meteorites and the processes that result in movements of volatile elements on asteroidal bodies. We have examined the I-Xe and Ar-Ar systems of the plagioclase-rich achondrite, Graves Nunataks 06129 by high-resolution laser step-heating of irradiated samples. Iodine and 129Xe∗ are both present but are released at different temperatures and do not show a correlation, therefore the I-Xe system in GRA 06129 has no chronological significance. We propose that radiogenic 129Xe∗ was lost from primary phases and parentless 129Xe∗ was later introduced into the rock by interaction with a fluid sourced from a reservoir that evolved with a high I/Xe ratio. This could have been the same halogen-rich fluid that induced the conversion of merrillite and pyroxene into chlorapatite. Inherited 40Ar (i.e. not generated by in situ decay of 40K) is also present in one of three fragments studied here and may have been introduced at the same time as parentless 129Xe∗.

  19. Above-threshold ionization of noble gases in elliptically polarized fields: Effects of atomic polarization on photoelectron angular distributions (United States)

    Wang, YanLan; Yu, ShaoGang; Lai, XuanYang; Liu, XiaoJun; Chen, Jing


    We theoretically investigate the atomic polarization effect on photoelectron angular distributions (PADs) in above-threshold ionization of noble gases with elliptically polarized laser fields at wavelength of 800 nm, ellipticity of 0.25, and intensity of 1.5 ×1014W/cm2 . Simulations based on a semiclassical model that includes both the ionic Coulomb potential and the atomic polarization effect show surprisingly little difference between PADs for Ar, Kr, and Xe, which is in good agreement with recent experimental observations. Our calculations reveal that the atomic polarization effect increases the distance of the tunnel exit point of the photoelectron to the parent ion and weakens the strength of the interaction between the parent ion and the photoelectron on its subsequent classical propagation. As a result, the forward-scattering electrons which contribute to the main lobes in PADs are substantially suppressed. Our results indicate that the insensitivity of PADs for Ar, Kr, and Xe may be closely related to the influence of the atomic polarization effect on the photoelectron dynamics in the strong laser field.

  20. Formation of noble-gas hydrides and decay of solvated protons revisited: diffusion-controlled reactions and hydrogen atom losses in solid noble gases. (United States)

    Tanskanen, Hanna; Khriachtchev, Leonid; Lignell, Antti; Räsänen, Markku; Johansson, Susanna; Khyzhniy, Ivan; Savchenko, Elena


    UV photolysis and annealing of C2H2/Xe, C2H2/Xe/Kr, and HBr/Xe matrices lead to complicated photochemical processes and reactions. The dominating products in these experiments are noble-gas hydrides with general formula HNgY (Ng = noble-gas atom, Y = electronegative fragment). We concentrate on distinguishing the local and global mobility and losses of H atoms, barriers of the reactions, and the decay of solvated protons. Different deposition temperatures change the amount of lattice imperfections and thus the amount of traps for H atoms. The averaged distance between reacting species influencing the reaction kinetics is controlled by varying the precursor concentration. A number of solid-state processes connected to the formation of noble-gas hydrides and decay of solvated protons are discussed using a simple kinetic model. The most efficient formation of noble-gas hydrides is connected with global (long-range) mobility of H atoms leading to the H + Xe + Y reaction. The highest concentration of noble-gas hydrides was obtained in matrices of highest optical quality, which probably have the lowest concentration of defects and H-atom losses. In matrices with high amount of geometrical imperfections, the product formation is inefficient and dominated by a local (short-range) process. The decay of solvated protons is rather local than a global process, which is different from the formation of noble-gas molecules. However, the present data do not allow distinguishing local proton and electron mobilities. Our previous results indicate that these are electrons which move to positively-charged centers and neutralize them. It is believed that the image obtained here for solid xenon is applicable to solid krypton whereas the case of argon deserves special attention.

  1. Geology and ground-water resources of Nobles County, and part of Jackson County, Minnesota (United States)

    Norvitch, Ralph F.


    The area described in this report is in southwestern Minnesota, about 130 miles southwest of Minneapolis and St. Paul. It includes; Nobles County and the western tier of townships in Jackson County, a total of 864 square miles. Worthington, the Nobles County seat, is the largest city in the area, having a population of 9,015 persons (1960 census). Farming is the leading occupation, and food processing is the major industry. Critical water shortages have occurred in several parts of the area.

  2. H(3) (+) as a trap for noble gases--2: structure and energetics of XH(3) (+) complexes from X=neon to xenon. (United States)

    Pauzat, F; Ellinger, Y


    The affinity of H(3) (+) to combine with noble gases X has been investigated from neon to xenon using ab initio coupled cluster [CCSD and CCSD(T)] and density functional BH&HLYP levels of theory. For all noble gases, the stable structures belong to a C(2v) symmetry with an apex of the H(3) (+) triangle pointing to the noble gas. The structure of the complexes changes gradually from a practically pure Ne-H(3) (+) arrangement to a situation close to XeH(+)-H(2). A topological analysis of the electron localization function is used to illustrate the changes in the bonding along the series. The lowest dissociation energies of NeH(3) (+) and ArH(3) (+) ( approximately 1 and approximately 7 kcalmol) correspond to the breaking of the complexes according to X+H(3) (+), while the lowest dissociation energies of KrH(3) (+) and XeH(3) (+) ( approximately 8 and approximately 3 kcalmol) correspond to the breaking according to XH(+)+H(2). Rotational constants and harmonic frequencies are reported. Apart from XeH(3) (+) whose dipole moment (mu=2.6 D) may not be large enough, all the other complexes with dipole moments in the range of 6-8 D should be reasonable targets for detection by microwave spectroscopy. The present calculations are intended to stimulate both laboratory experiments and spatial observations since the possible sequestration of noble gases by H(3) (+) may have strong implications on the composition of astrophysical objects.

  3. Concerning the width of spark channels with different polarities in submicrosecond sliding discharges in noble gases (United States)

    Trusov, K. K.


    Previously, the parameters of submicrosecond (with a duration of ceramic surface in Ne, Ar, and Xe were studied only for the negative polarity of the applied voltage. The experimental data indicate that the channels expand in the transverse direction mainly due to electron drift from the channel surface layer under the action of the electric field perpendicular to the channel axis and subsequent gas ionization by these electrons. To investigate mechanisms for the channel development in a sliding discharge—in particular, to determine the contribution of electron drift—it is necessary to carry out experiments similar to those performed earlier for the opposite polarity of the applied voltage. Here, the results of measurements of the widths of the spark channels of negativeand positive-polarity sliding discharges excited in Ne, Ar, and Xe at pressures of 30 and 100 kPa are presented and discussed. It is shown that, depending on the pressure and sort of gas, the averaged optical width of positive-polarity channels is smaller by a factor of 1.27-1.60 than that of negative-polarity channels. The experimental data are analyzed using the theory of propagation of ionization waves with different polarities in gases. Analysis has shown that electron diffusion contributes insignificantly to channel expansion and that, for both polarities, the channel expansion rate exceeds the electron drift velocity in the transverse electric field near the channel. In the framework of the so-called approximation of nonlocalized initial conditions, the measured ratio between of the widths of negativeand positive-polarity channels and their relation to the electron mobility are explained by the channel expansion governed by both electron drift and primary free electrons produced by a short-term source in a narrow region ahead of the front of the expansion wave. Numerical simulations show that the width of this region is comparable with that of the wave front and is more than one order of

  4. On the abundances of noble and biologically relevant gases in Lake Vostok, Antarctica. (United States)

    Mousis, Olivier; Lakhlifi, Azzedine; Picaud, Sylvain; Pasek, Matthew; Chassefière, Eric


    Motivated by the possibility of comparing theoretical predictions of Lake Vostok's composition with future in situ measurements, we investigated the composition of clathrates that are expected to form in this environment from the air supplied to the lake by melting ice. To establish the best possible correlation between the lake water composition and that of air clathrates formed in situ, we used a statistical thermodynamic model based on the description of the guest-clathrate interaction by a spherically averaged Kihara potential with a nominal set of potential parameters. We determined the fugacities of the different volatiles present in the lake by defining a "pseudo" pure substance dissolved in water owning the average properties of the mixture and by using the Redlich-Kwong equation of state to mimic its thermodynamic behavior. Irrespective of the clathrate structure considered in our model, we found that xenon and krypton are strongly impoverished in the lake water (a ratio in the 0.04-0.1 range for xenon and a ratio in the ≈ 0.15-0.3 range for krypton) compared to their atmospheric abundances. Argon and methane were also found to be depleted in the Lake Vostok water by factors in the 0.5-0.95 and 0.3-0.5 ranges, respectively, compared to their atmospheric abundances. On the other hand, the carbon dioxide abundance was found to be substantially enriched in the lake water compared to its atmospheric abundance (by a factor in the 1.6-5 range at 200 residence times). The comparison of our predictions of the CO2 and CH4 mole fractions in Lake Vostok with future in situ measurements will allow disentangling between the possible supply sources.

  5. The temperature and precipitation reconstructions on Swiss stalagmites with a special emphasis on altitude gradient using noble-gases, δO-18 and δD of fluid inclusions (United States)

    Ghadiri, Elaheh; Brennwald, Matthias; Kipfer, Rolf


    We present the results of an application of 'Combined Vacuum Crushing and Sieving (CVCS)' system (e.g., allowing to crush samples to defined grain size in vacuum) for the first time to stalagmites grown in cold climates during the last glacial-interglacial transition, but at different altitudes. Recently, concentrations of dissolved atmospheric noble gases in fluid inclusions of stalagmites were used to reconstruct past ambient cave temperatures, the annual mean temperature and hydrological conditions when the water was trapped. To reconstruct temperatures from noble gases (noble gas temperature: NGT) in water-filled inclusions, we processed samples from Swiss stalagmites M6 from Milandre cave (400 m.a.s.l) and GEF1 from Grotte aux Fées cave (895 m.a.s.l) covering the climatic transitions Allerød-Younger Dryas-Holocene. Water content. The amount of water extracted per unit mass of calcite fabric (e.g., 'water yield': WT) was shown to be a measure of the total water content. The data shows that the WT systematically changes with δ18Ocalcite of the calcite. We therefore conclude that WT records can be linked on changes in drip rates and thus can be used to track changes of past precipitation even in cold regions. Noble gases. Noble gas analysis shows that the annual mean temperatures in Milandre cave were 2.2±2.0°C during the late Allerød and dropped to 0±2°C at the Younger Dryas. Such temperatures close 0°C indicate that drip water supply stopped in response to the formation of permafrost conditions around the cave preventing further stalagmite growth. However, one late Holocene sample gave a cave temperature of 8.7±1.4°C agreeing generally with present day annual mean temperature. The annual mean temperature of 5.7±1.3°C from GEF1 was determined for the early Holocene. The observed data show systematic variations with sample elevation, e.g., higher temperature from lower altitude and vice versa. Combining the isotopic composition of water in fluid

  6. Noble gases without anesthetic properties protect myocardium against infarction by activating prosurvival signaling kinases and inhibiting mitochondrial permeability transition in vivo. (United States)

    Pagel, Paul S; Krolikowski, John G; Shim, Yon Hee; Venkatapuram, Suneetha; Kersten, Judy R; Weihrauch, Dorothee; Warltier, David C; Pratt, Phillip F


    The anesthetic noble gas, xenon, produces cardioprotection. We hypothesized that other noble gases without anesthetic properties [helium (He), neon (Ne), argon (Ar)] also produce cardioprotection, and further hypothesized that this beneficial effect is mediated by activation of prosurvival signaling kinases [including phosphatidylinositol-3-kinase, extracellular signal-regulated kinase, and 70-kDa ribosomal protein s6 kinase] and inhibition of mitochondrial permeability transition pore (mPTP) opening in vivo. Rabbits (n = 98) instrumented for hemodynamic measurement and subjected to a 30-min left anterior descending coronary artery (LAD) occlusion and 3 h reperfusion received 0.9% saline (control), three cycles of 70% He-, Ne-, or Ar-30% O2 administered for 5 min interspersed with 5 min of 70% N2-30% O2 before LAD occlusion, or three cycles of brief (5 min) ischemia interspersed with 5 min reperfusion before prolonged LAD occlusion and reperfusion (ischemic preconditioning). Additional groups of rabbits received selective inhibitors of phosphatidylinositol-3-kinase (wortmannin; 0.6 mg/kg), extracellular signal-regulated kinase (PD 098059; 2 mg/kg), or 70-kDa ribosomal protein s6 kinase (rapamycin; 0.25 mg/kg) or mPTP opener atractyloside (5 mg/kg) in the absence or presence of He pretreatment. He, Ne, Ar, and ischemic preconditioning significantly (P noble gases without anesthetic properties produce cardioprotection by activating prosurvival signaling kinases and inhibiting mPTP opening in rabbits.

  7. Estimation of self-absorption effect on aluminum emission in the presence of different noble gases: comparison between thin and thick plasma emission. (United States)

    Rezaei, F; Karimi, P; Tavassoli, S H


    Aluminum spectra in the noble gases of helium and argon at initial delay times after plasma formation are numerically calculated. Temporal behavior of plasma emissions up to 200 ns after laser irradiation is investigated. Plasma parameters are computed by coupling the thermal model of laser ablation, hydrodynamic of plasma expansion, and Saha-Eggert equations. A spectrum is constructed from the superposition of 13 strong lines of aluminum and several strong lines of ambient gases. Spectral radiations are superimposed on a continuous emission composed of bremsstrahlung and recombination radiation. The self-absorption effect on plasma radiation at 1 atm gas pressure is studied. In this paper, a comparison between thin and thick aluminum radiation is done. Furthermore, the self-absorption coefficient of each strong line at laser energies of 0.5, 0.7, 0.9, and 1.1 GW/cm(2) is estimated. Results show that at specific laser energy, the self-absorption effect in argon is more significant than in helium. For most of the spectral lines in both noble gases, the self-absorption coefficient will diminish with the delay time. As indicated with passing time, the line widths of the self-absorbed lines will rise. More intense continuous emissions are observed at higher wavelengths, and these radiations will be increased with laser energy.

  8. The first example of commensurate adsorption of atomic gas in a MOF and effective separation of xenon from other noble gases

    KAUST Repository

    Wang, Hao


    In industry, cryogenic rectification for separating xenon from other noble gases such as krypton and argon is an energy and capital intensive process. Here we show that a microporous metal-organic framework, namely Co 3(HCOO)6 is capable of effective capture and separation of xenon from other noble gases. Henry\\'s constant, isosteric heat of adsorption (Qst), and IAST selectivity are calculated based on single component sorption isotherms. Having the highest Qst reported to date, Co 3(HCOO)6 demonstrates high adsorption capacity for xenon and its IAST selectivity for Xe-Kr is the largest among all MOFs investigated to date. To mimic real world conditions, breakthrough experiments are conducted on Xe-Kr binary mixtures at room temperature and 1 atmosphere. The results are consistent with the calculated data. These findings show that Co 3(HCOO)6 is a promising candidate for xenon capture and purification. Our gas adsorption measurements and molecular simulation study also reveal that the adsorption of xenon represents the first example of commensurate adsorption of atomic gases near ambient conditions. © 2014 The Royal Society of Chemistry.

  9. Masses of noble gases

    CERN Multimedia

    Marx, G H; Herfurth, F; Stora, T; Blaum, K; Beck, D; Audi, G; Rosenbusch, M

    The so-called magic numbers, cornerstones of the quantum nuclear ensemble, are now known to lose their supernatural powers far from the protected valley of stability. To complement the well-established (but not yet well-understood) case of N = 20, we propose to examine the erstwhile N = 28 shell closure via a measurement of the important (but unknown) mass of the nuclide $^{48}$Ar. The quenching of a shell closure, a mechanism as mysterious as the reason for magic numbers themselves, also has important consequences in nucleosynthesis. While $^{48}$Ar is not part of the region concerned by the canonical rapid neutro-capture r-process, the question of shell strength is of great importance for heavier nuclides. The location of the r-process path would benefit from extending the succesful ISOTRAP krypton mass measurements beyond the N = 58 sub-shell to $^{96-98}$Kr. Modeling the complementary rapid proton-capture rp- process, putative source of some proton-rich species, requires the mass of $^{70}$Kr, near the e...

  10. U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples (United States)

    Hunt, Andrew G.


    This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water. A synopsis of the instrumentation used, procedures followed, calibration practices, standards used, and a quality assurance and quality control program is presented. The report outlines the day-to-day operation of the Residual Gas Analyzer Model 200, Mass Analyzer Products Model 215–50, and ultralow vacuum extraction line along with the sample handling procedures, noble gas extraction and purification, instrument measurement procedures, instrumental data acquisition, and calculations for the conversion of raw data from the mass spectrometer into noble gas concentrations per unit mass of water analyzed. Techniques for the preparation of artificial dissolved gas standards are detailed and coupled to a quality assurance and quality control program to present the accuracy of the procedures used in the laboratory.

  11. Rare gases, water, and carbon in kaersutites (United States)

    Poreda, Robert J.; Basu, Asish R.


    Kaersutites from Kakanui, New Zealand and from three localities in the southwestern United States have been analyzed for rare gases, water and carbon to investigate the volatile signature of the sub-continental mantle. This study does not confirm the high 3He/ 4He and 21Ne/ 22Ne ratios reported by Saito et al. [1] for the Kakanui kaersutite. Instead, a 3He/ 4He ratio of 6 RA and atmospheric 21Ne/ 22Ne ratios were measured which are consistent with our current knowledge of the earth's mantle. A low 40Ar/ 36Ar of 320 and more than 10 -8 cm 3/g of 36Ar confirms the argon results of Saito et al. and indicates that significant quantities of 36Ar reside in this portion of the mantle. Kaersutites from the southwestern United States (Arizona) have a heterogeneous helium isotope signature, ranging from 8.8 RA at San Carlos to 0.46 at Hoover Dam. All D/H ratios for the water in kaersutites (-56‰ to -78‰) represent typical mantle values with no apparent correlation with 3He/ 4He. The correlation of increasing carbon content (140-400 ppm) with increasing δ 13C (-24.5‰ to -16.7‰) may reflect differences in the proportions of oxidized and reduced carbon in these samples.

  12. Ab initio molecular orbital studies of the vibrational spectra of the van der Waals complexes of boron trifluoride with the noble gases. (United States)

    Ford, Thomas A


    The molecular structures, interaction energies, charge transfer properties and vibrational spectra of the van der Waals complexes formed between boron trifluoride and the noble gases neon, argon, krypton and xenon have been computed using second and fourth order Møller-Plesset perturbation theory and the Los Alamos National Laboratory LANL2DZ basis set. The complexes are all symmetric tops, with the noble gas atom acting as a sigma electron donor along the C3 axis of the BF3 molecule. The interaction energies are all vanishingly small, and the amount of charge transferred in each case is of the order of 0.01e. The directions of the wavenumber shifts of the symmetric bending (nu2) and antisymmetric stretching (nu3) modes of the BF3 fragment confirm those determined experimentally, and the shifts are shown to correlate well with the polarizability of the noble gas atom and the inverse sixth power of the intermonomer separation. The nu2 mode is substantially more sensitive to complexation than the nu3 vibration.

  13. Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage (United States)

    Torgersen, T.; Kennedy, B. M.


    Hydrocarbons from the Elk Hills Naval Petroleum Reserve (NPR#1), Bakersfield, CA, are enriched in heavy noble gases. The 132Xe/ 36Ar ratios are as high as ˜576 times the ratio in air and represent the largest relative Xe-enrichments ever observed in terrestrial fluids. The Xe isotopic composition is indistinguishable from air. We show that these samples cannot be explained by equilibration of oil with air saturated water and secondary enrichment via a Rayleigh distillation gas stripping process. Based on laboratory studies of others with potential petroleum source rocks, we believe the source of this enriched heavy noble gas component was adsorbed air initially trapped in/on the source rocks that was expelled and mixed with the hydrocarbons during expulsion and primary migration. Kr and Xe enrichments decrease with increasing 36Ar concentration. We propose a model in which an initial Kr-Xe-enriched hydrocarbon becomes diluted with noble gases extracted from air saturated groundwater during expulsion, migration, and storage. The model generates an integrated water/hydrocarbon ratio for the production fluid which indicates a minimal role for water in hydrocarbon expulsion and migration. The results are interpreted to provide time/geometrical constraints on the mechanisms by which hydrocarbons can migrate as a separate phase.

  14. New evidence for chondritic lunar water from combined D/H and noble gas analyses of single Apollo 17 volcanic glasses (United States)

    Füri, Evelyn; Deloule, Etienne; Gurenko, Andrey; Marty, Bernard


    In order to assess the proportion of solar, cosmogenic, and indigenous water (hydrogen) trapped in individual Ti-rich lunar volcanic glasses (LVGs) from the 74002 core obtained during the Apollo 17 mission, we coupled ion microprobe measurements of water abundances and D/H ratios with CO2 laser extraction-static mass spectrometry analyses of noble gases (He, Ne, Ar). The large (∼300-400 μm in diameter) LVGs studied here contain a small amount of solar wind (SW) volatiles implanted at the grain surfaces, as indicated by the small concentrations of solar helium and neon that represent ⩽5% of the respective total noble gas abundances. The large proportion of volume-correlated cosmogenic gases reflects an exposure duration of ∼28 Ma, on average, of the glasses at the lunar surface. Hydrogen abundances determined in the grain interiors of glassy and partially-crystalline LVGs are equivalent to between 6.5 and 54.3 ppm H2O. Based on the noble gas exposure ages, the correction of the measured hydrogen isotope composition for in situ production of cosmogenic deuterium by spallation reactions varies between -5‰ to -254‰ for the different grains. Corrected δD values range from +38‰ to +809‰ in the LVGs and are anti-correlated with the water content, consistent with extensive hydrogen isotope fractionation during kinetic H2 loss from a lunar melt with an inferred initial isotope signature of the order of -100‰ and a water content of 100-300 ppm. The detection of water in these primitive lunar melts confirms the presence of a non-anhydrous mantle reservoir within the Moon. Furthermore, our results reveal that the hydrogen isotope composition of water in the melt source of the 74002 LVGs is similar to that of carbonaceous chondrites. These observations indicate that the contribution of deuterium-enriched cometary water to the Earth-Moon system is negligible.

  15. Anionic chemistry of noble gases: formation of Mg-NG (NG = Xe, Kr, Ar) compounds under pressure. (United States)

    Miao, Mao-Sheng; Wang, Xiao-Li; Brgoch, Jakoah; Spera, Frank; Jackson, Matthew G; Kresse, Georg; Lin, Hai-Qing


    While often considered to be chemically inert, the reactivity of noble gas elements at elevated pressures is an important aspect of fundamental chemistry. The discovery of Xe oxidation transformed the doctrinal boundary of chemistry by showing that a complete electron shell is not inert to reaction. However, the reductive propensity, i.e., gaining electrons and forming anions, has not been proposed or examined for noble gas elements. In this work, we demonstrate, using first-principles electronic structure calculations coupled to an efficient structure prediction method, that Xe, Kr, and Ar can form thermodynamically stable compounds with Mg at high pressure (≥125, ≥250, and ≥250 GPa, respectively). The resulting compounds are metallic and the noble gas atoms are negatively charged, suggesting that chemical species with a completely filled shell can gain electrons, filling their outermost shell(s). Moreover, this work indicates that Mg2NG (NG = Xe, Kr, Ar) are high-pressure electrides with some of the electrons localized at interstitial sites enclosed by the surrounding atoms. Previous predictions showed that such electrides only form in Mg and its compounds at very high pressures (>500 GPa). These calculations also demonstrate strong chemical interactions between the Xe 5d orbitals and the quantized interstitial quasiatom (ISQ) orbitals, including the strong chemical bonding and electron transfer, revealing the chemical nature of the ISQ.

  16. Mean annual temperature in New Zealand during the last glacial maximum derived from dissolved noble gases in groundwater (United States)

    Seltzer, A. M.; Stute, M.; Morgenstern, U.; Stewart, M. K.; Schaefer, J. M.


    This study presents a reconstruction of mean annual surface temperature in New Zealand over the last glacial period using groundwater noble gas paleothermometry. Low resolution 14C-derived mean recharge ages of groundwater from the Deep Moutere, Deep Wairau, and Taranaki aquifers range from roughly 41,500 yr to present, including the last glacial maximum (LGM). Modeled noble gas temperatures of probable glacial-age samples range from roughly 3.7-6.2 °C cooler than present. We present an error-weighted mean cooling of 4.6 ± 0.5°C relative to present during last glacial period. The screened depth intervals of some wells sampled in this study allow for a degree of mixing during extraction between groundwater layers of different recharge age. Mixing with modern groundwater may slightly elevate the noble gas temperatures (NGTs) of glacial-age samples while making them appear substantially younger. Given the uncertainty in dating, we cannot rule out a larger LGM temperature depression of up to ∼6 °C. The ∼4.6 °C cooling estimate agrees with a number of terrestrial paleoclimate reconstructions near the study area as well as the majority of nearby paleoceanographic temperature studies.

  17. Coexistence and interfacial properties of a triangle-well mimicking the Lennard-Jones fluid and a comparison with noble gases. (United States)

    Bárcenas, M; Reyes, Y; Romero-Martínez, A; Odriozola, G; Orea, P


    Coexistence and interfacial properties of a triangle-well (TW) fluid are obtained with the aim of mimicking the Lennard-Jones (LJ) potential and approach the properties of noble gases. For this purpose, the scope of the TW is varied to match vapor-liquid densities and surface tension. Surface tension and coexistence curves of TW systems with different ranges were calculated with replica exchange Monte Carlo and compared to those data previously reported in the literature for truncated and shifted (STS), truncated (ST), and full Lennard-Jones (full-LJ) potentials. We observed that the scope of the TW potential must be increased to approach the STS, ST, and full-LJ properties. In spite of the simplicity of TW expression, a remarkable agreement is found. Furthermore, the variable scope of the TW allows for a good match of the experimental data of argon and xenon.

  18. Combined action of the bound-electron nonlinearity and the tunnel-ionization current in low-order harmonic generation in noble gases. (United States)

    Sapaev, Usman; Husakou, Anton; Herrmann, Joachim


    We study numerically low-order harmonic generation in noble gases pumped by intense femtosecond laser pulses in the tunneling ionization regime. We analyze the influence of the phase-mismatching on this process, caused by the generated plasma, and study in dependence on the pump intensity the origin of harmonic generation arising either from the bound-electron nonlinearity or the tunnel-ionization current. It is shown that in argon the optimum pump intensity of about 100 TW/cm² leads to the maximum efficiency, where the main contribution to low-order harmonics originates from the bound-electron third and fifth order susceptibilities, while for intensities higher than 300 TW/cm² the tunnel-ionization current plays the dominant role. Besides, we predict that VUV pulses at 133 nm can be generated with relatively high efficiency of about 1.5 × 10⁻³ by 400 nm pump pulses.

  19. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making (United States)

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg


    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  20. Petrography, classification, oxygen isotopes, noble gases, and cosmogenic records of Kamargaon (L6) meteorite: The latest fall in India (United States)

    Ray, D.; Mahajan, R. R.; Shukla, A. D.; Goswami, T. K.; Chakraborty, S.


    A single piece of meteorite fell on Kamargaon village in the state of Assam in India on November 13, 2015. Based on mineralogical, chemical, and oxygen isotope data, Kamargaon is classified as an L-chondrite. Homogeneous olivine (Fa: 25 ± 0.7) and low-Ca pyroxene (Fs: 21 ± 0.4) compositions with percent mean deviation of different shock stages, e.g., S3 and S4 (Stöffler et al.; however, local presence of quenched metal-sulfide melt within shock veins/pockets suggest disequilibrium melting and relatively higher shock stage of up to S5 (Bennett and McSween). Based on noble gas isotopes, the cosmic-ray exposure age is estimated as 7.03 ± 1.60 Ma and nitrogen isotope composition (δ15N = 18‰) also correspond well with the L-chondrite group. The He-U, Th, and K-Ar yield younger ages (170 ± 25 Ma 684 ± 93, respectively) and are discordant. A loss of He during the resetting event is implied by the lower He-U and Th age. Elemental ratios of trapped Ar, Kr, and Xe can be explained through the presence of a normal Q noble gas component. Relatively low activity of 26Al (39 dpm/kg) and the absence of 60Co activity suggest a likely low shielding depth and envisage a small preatmospheric size of the meteoroid (<10 cm in radius). The Kr isotopic ratios (82Kr/84Kr) further argue that the meteorite was derived from a shallow depth.

  1. Noble gas fractionation during subsurface gas migration (United States)

    Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.


    Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.

  2. Seawater subduction controls the heavy noble gas composition of the mantle. (United States)

    Holland, Greg; Ballentine, Chris J


    The relationship between solar volatiles and those now in the Earth's atmosphere and mantle reservoirs provides insight into the processes controlling the acquisition of volatiles during planetary accretion and their subsequent evolution. Whereas the light noble gases (helium and neon) in the Earth's mantle preserve a solar-like isotopic composition, heavy noble gases (argon, krypton and xenon) have an isotopic composition very similar to that of the modern atmosphere, with radiogenic and (in the case of xenon) solar contributions. Mantle noble gases in a magmatic CO2 natural gas field have been previously corrected for shallow atmosphere/groundwater and crustal additions. Here we analyse new data from this field and show that the elemental composition of non-radiogenic heavy noble gases in the mantle is remarkably similar to that of sea water. We challenge the popular concept of a noble gas 'subduction barrier'--the convecting mantle noble gas isotopic and elemental composition is explained by subduction of sediment and seawater-dominated pore fluids. This accounts for approximately 100% of the non-radiogenic argon and krypton and 80% of the xenon. Approximately 50% of the convecting mantle water concentration can then be explained by this mechanism. Enhanced recycling of subducted material to the mantle plume source region then accounts for the lower ratio of radiogenic to non-radiogenic heavy noble gas isotopes and higher water content of plume-derived basalts.

  3. Alkaline membrane water electrolysis with non-noble catalysts

    DEFF Research Database (Denmark)

    Kraglund, Mikkel Rykær

    As renewable energy sources reach higher grid penetration, large scale energy storage solutions are becoming increasingly important. Hydrogen produced with renewable energy by water electrolysis is currently the only option to solve this challenge on a global scale, and green hydrogen is essential...... these issues by introducing alkaline polymeric membranes and efficient electrodes based on novel materials. Polymer electrolyte membranes with sufficient OH– -conductivity enable a drastic reduction of the electrode spacing, which lead to improved ohmic properties enabling operation at higher current density....... This, combined with better gas separation properties and a higher operating flexibility, have the prospects of significantly reducing the capex and opex of electrolysis systems, and the cost of green hydrogen. Towards this goal, membranes based on poly(2,2’-(mphenylene)-5,5’-bibenzimidazole) (m...

  4. A randomized trial of the effects of the noble gases helium and argon on neuroprotection in a rodent cardiac arrest model. (United States)

    Zuercher, Patrick; Springe, Dirk; Grandgirard, Denis; Leib, Stephen L; Grossholz, Marius; Jakob, Stephan; Takala, Jukka; Haenggi, Matthias


    The noble gas xenon is considered as a neuroprotective agent, but availability of the gas is limited. Studies on neuroprotection with the abundant noble gases helium and argon demonstrated mixed results, and data regarding neuroprotection after cardiac arrest are scant. We tested the hypothesis that administration of 50% helium or 50% argon for 24 h after resuscitation from cardiac arrest improves clinical and histological outcome in our 8 min rat cardiac arrest model. Forty animals had cardiac arrest induced with intravenous potassium/esmolol and were randomized to post-resuscitation ventilation with either helium/oxygen, argon/oxygen or air/oxygen for 24 h. Eight additional animals without cardiac arrest served as reference, these animals were not randomized and not included into the statistical analysis. Primary outcome was assessment of neuronal damage in histology of the region I of hippocampus proper (CA1) from those animals surviving until day 5. Secondary outcome was evaluation of neurobehavior by daily testing of a Neurodeficit Score (NDS), the Tape Removal Test (TRT), a simple vertical pole test (VPT) and the Open Field Test (OFT). Because of the non-parametric distribution of the data, the histological assessments were compared with the Kruskal-Wallis test. Treatment effect in repeated measured assessments was estimated with a linear regression with clustered robust standard errors (SE), where normality is less important. Twenty-nine out of 40 rats survived until day 5 with significant initial deficits in neurobehavioral, but rapid improvement within all groups randomized to cardiac arrest. There were no statistical significant differences between groups neither in the histological nor in neurobehavioral assessment. The replacement of air with either helium or argon in a 50:50 air/oxygen mixture for 24 h did not improve histological or clinical outcome in rats subjected to 8 min of cardiac arrest.

  5. On the size and structure of helium snowballs formed around charged atoms and clusters of noble gases. (United States)

    Bartl, Peter; Leidlmair, Christian; Denifl, Stephan; Scheier, Paul; Echt, Olof


    Helium nanodroplets doped with argon, krypton, or xenon are ionized by electrons and analyzed in a mass spectrometer. HenNgx(+) ions containing up to seven noble gas (Ng) atoms and dozens of helium atoms are identified; the high resolution of the mass spectrometer combined with advanced data analysis make it possible to unscramble contributions from isotopologues that have the same nominal mass but different numbers of helium or Ng atoms, such as the magic He20(84)Kr2(+) and the isobaric, nonmagic He41(84)Kr(+). Anomalies in these ion abundances reveal particularly stable ions; several intriguing patterns emerge. Perhaps most astounding are the results for HenAr(+), which show evidence for three distinct, solid-like solvation shells containing 12, 20, and 12 helium atoms. This observation runs counter to the common notion that only the first solvation shell is solid-like but agrees with calculations by Galli et al. for HenNa(+) [J. Phys. Chem. A 2011, 115, 7300] that reveal three shells of icosahedral symmetry. HenArx(+) (2 ≤ x ≤ 7) ions appear to be especially stable if they contain a total of n + x = 19 atoms. A sequence of anomalies in the abundance distribution of HenKrx(+) suggests that rings of six helium atoms are inserted into the solvation shell each time a krypton atom is added to the ionic core, from Kr(+) to Kr3(+). Previously reported strong anomalies at He12Kr2(+) and He12Kr3(+) [Kim , J. H.; et al. J. Chem. Phys. 2006, 124, 214301] are attributed to a contamination. Only minor local anomalies appear in the distributions of HenXex(+) (x ≤ 3). The distributions of HenKr(+) and HenXe(+) show strikingly similar, broad features that are absent from the distribution of HenAr(+); differences are tentatively ascribed to the very different fragmentation dynamics of these ions.

  6. Nonlinear optical polarization response and plasma generation in noble gases: Comparison of metastable-electronic-state-approach models to experiments (United States)

    Bahl, Anand; Wahlstrand, Jared K.; Zahedpour, Sina; Milchberg, Howard M.; Kolesik, Miroslav


    The nonlinear polarization response and plasma generation produced by intense optical pulses, modeled by the metastable-electronic-state approach, are verified against space-and-time resolved measurements with single-shot supercontinuum spectral interferometry. This first of a kind theory-experiment comparison is done in the intensity regime typical for optical filamentation, where self-focusing and plasma generation play competing roles. Excellent agreement between the theory and experiment shows that the self-focusing nonlinearity can be approximated by a single resonant state. Moreover, we demonstrate that inclusion of the post-adiabatic corrections, previously tested only in theoretic models, provides a viable description of the ionization rate in real gases.

  7. Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases. (United States)

    Bartocci, Alessio; Belpassi, Leonardo; Cappelletti, David; Falcinelli, Stefano; Grandinetti, Felice; Tarantelli, Francesco; Pirani, Fernando


    The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl4 and CF4. Their investigation was motivated by the widespread current interest for the intermolecular halogen bonding (XB), a structural motif recognized to play a role in fields ranging from elementary processes to biochemistry. The simulation of the static and dynamic behaviors of complex systems featuring XB requires the formulation of reliable and accurate model potentials, whose development relies on the detailed characterization of strength and nature of the interactions occurring in simple exemplary halogenated systems. We thus selected the prototypical Ng-CCl4 and Ng-CF4 and performed high-resolution molecular beam scattering experiments to measure the absolute scale of their intermolecular potentials, with high sensitivity. In general, we expected to probe typical van der Waals interactions, consisting of a combination of size (exchange) repulsion with dispersion/induction attraction. For the He/Ne-CF4, the analysis of the glory quantum interference pattern, observable in the velocity dependence of the integral cross section, confirmed indeed this expectation. On the other hand, for the He/Ne/Ar-CCl4, the scattering data unravelled much deeper potential wells, particularly for certain configurations of the interacting partners. The experimental data can be properly reproduced only including a shifting of the repulsive wall at shorter distances, accompanied by an increased role of the dispersion attraction, and an additional short-range stabilization component. To put these findings on a firmer ground, we performed, for selected geometries of the interacting complexes, accurate theoretical calculations aimed to evaluate the intermolecular interaction and the effects of the complex formation on the electron charge density of the constituting moieties. It was thus ascertained that the adjustments of the potential suggested by the analysis of the

  8. Investigating the Effect of the Binary Mixtures Composition of Noble Gases on Their Thermodynamic and Transport Properties

    Directory of Open Access Journals (Sweden)

    S. A. Burtsev


    Full Text Available The paper presents possible application fields of the binary noble gas mixtures with low Prandtl numbers. It shows that it is expedient to select these mixtures as the working fluids for closed Brayton cycle gas-turbine installations, thermo-acoustic engines and for the gas dynamic energy separation device (Leontiev tube. As follows from the analysis, He-Ar, He-Kr, and HeXe mixtures have proven to be the most attractive choice. The paper has analyzed the calculation results for coefficient of dynamic viscosity, coefficient of thermal conductivity, and for heat capacity at constant pressure for the given mixtures in terms of mixture molecular weights at pressures of 2MPa and 7MPa and temperatures of 400 and 1200°K. According to data of experiments and calculations available in public sources published by another authors, the results are verified. It was found that at constant pressure within the examined range of parameters (i.e. pressure, temperature, mixture molecular weight the obtained heat capacity values are in good agreement with the values of the verification data. In calculating dynamic viscosity coefficient for any pressure and temperature the utilized technique provides results for He-Ar and He-Kr mixtures within the entire range of the molecular weights, which are, essentially, as good as shown by international verification techniques. However, at high pressures and low temperatures for He-Xe mixture with molecular weights close to the pure Xe the divergence was found to be as high as 25 % while for other parameter intervals under consideration and with the same mixture the difference does not exceed 10 %. A good agreement with the verification data is observed for the values of a thermal conductivity coefficient of He-Ar and He-Kr mixtures for any value of parameters, while for He-Xe mixture with molecular weights close to 60 g/mole independently of pressure the divergence can reach 30 % for 1200°K and 20 % for 400°K. It is shown

  9. Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Bartocci, Alessio; Cappelletti, David; Pirani, Fernando [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia 06123 (Italy); Belpassi, Leonardo [Istituto di Scienze e Tecnologie Molecolari del CNR, Perugia 06123 (Italy); Falcinelli, Stefano [Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, 06125 Perugia (Italy); Grandinetti, Felice [Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, 01100 Viterbo (Italy); Tarantelli, Francesco [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia 06123 (Italy); Istituto di Scienze e Tecnologie Molecolari del CNR, Perugia 06123 (Italy)


    The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl{sub 4} and CF{sub 4}. Their investigation was motivated by the widespread current interest for the intermolecular halogen bonding (XB), a structural motif recognized to play a role in fields ranging from elementary processes to biochemistry. The simulation of the static and dynamic behaviors of complex systems featuring XB requires the formulation of reliable and accurate model potentials, whose development relies on the detailed characterization of strength and nature of the interactions occurring in simple exemplary halogenated systems. We thus selected the prototypical Ng-CCl{sub 4} and Ng-CF{sub 4} and performed high-resolution molecular beam scattering experiments to measure the absolute scale of their intermolecular potentials, with high sensitivity. In general, we expected to probe typical van der Waals interactions, consisting of a combination of size (exchange) repulsion with dispersion/induction attraction. For the He/Ne-CF{sub 4}, the analysis of the glory quantum interference pattern, observable in the velocity dependence of the integral cross section, confirmed indeed this expectation. On the other hand, for the He/Ne/Ar-CCl{sub 4}, the scattering data unravelled much deeper potential wells, particularly for certain configurations of the interacting partners. The experimental data can be properly reproduced only including a shifting of the repulsive wall at shorter distances, accompanied by an increased role of the dispersion attraction, and an additional short-range stabilization component. To put these findings on a firmer ground, we performed, for selected geometries of the interacting complexes, accurate theoretical calculations aimed to evaluate the intermolecular interaction and the effects of the complex formation on the electron charge density of the constituting moieties. It was thus ascertained that the adjustments of the potential

  10. Determination of natural in vivo noble-gas concentrations in human blood.

    Directory of Open Access Journals (Sweden)

    Yama Tomonaga

    Full Text Available Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry.

  11. Transport of methane and noble gases during gas push-pull tests in variably saturated porous media. (United States)

    Gómez, Katherine; Gonzalez-Gil, Graciela; Schroth, Martin H; Zeyer, Josef


    The gas push-pull test (GPPT) is a single-well gas-tracer method to quantify in situ rates of CH4 oxidation in soils. To improve the design and interpretation of GPPT field experiments, gas component transport during GPPTs was examined in abiotic porous media over a range of water saturations (0.0 0.42). Gas-component transport during GPPTs was numerically simulated using estimated hydraulic parameters for the porous media and no fitting of data for the GPPTs. Numerical simulations accurately predicted the relative decline of the gaseous components in the breakthrough curves, but slightly overestimated recoveries at low Sw ( or = 0.49). Comparison of numerical simulations considering and not considering air-water partitioning indicated that removal of gaseous components through dissolution in pore water was not significant during GPPTs, even at Sw = 0.61. These data indicate that Ar is a good tracer for CH4 physical transport over the full range of Sw studied, whereas, at Sw > 0.61, any of the tracers could be used. Greater mass recovery at higher Sw raises the possibility to reduce gas flow rates, thereby extending GPPT times in environments such as tundra soils where low activity due to low temperatures may require longer test times to establish a quantifiable difference between reactant and tracer breakthrough curves.


    Directory of Open Access Journals (Sweden)

    D’AGARO E.


    Full Text Available Juvenile Astacus astacus (initial b.w.: 0.98 ± 0.06 g were cultured (30 crayfish/m2 in 200l tanks for 69 days. The experimental design was composed of three treatments as follows: control diet (C (crude protein: 28.4% of the total dried matter, “DM”; ether extract: 6.22% DM, water cress (W (crude protein: 20.7% DM; ether extract: 1.9% DM and control diet + water cress (C + W with thee replicates per treatment. Relative growth rate improved significantly (P < 0.05 in crayfish fed C + W (+ 110% compared to W (+ 43% and the control diet (+ 36%. Gross protein and lipid retentions of the treatment C + W were significantly higher than the control diet and water cress fed alone. At the end of the experiment, a higher survival rate of A. astacus was observed (P < 0.05 in the treatment C + W (67% and C (71% compared to the W (58%. These results suggest that the plant water cress (Nasturtium officinale can be used as supplemental food in noble crayfish feeding.

  13. Apparatus and method for purging hydrogen sulfide gases from well water

    Energy Technology Data Exchange (ETDEWEB)

    Schwall, J.A.


    An apparatus and method of ridding objectionable hydrogen sulfide gases from well water before pumping the water from the well is provided, wherein the water at the water table level in the well is aerated, causing turbulence in the well water, and facilitating the escape of hydrogen sulfide gases to the atmosphere. The apparatus (10) for ridding hydrogen sulfide gases from well water comprises means (16) for pumping well water (19) under pressure to a water delivery system of an edifice (30, 33), additional means (38) associated with the pumping means (16) for delivering a relatively small portion of the well water under pressure to the well water (19) in the well (12) to cause turbulence in the water to facilitate the escape of hydrogen sulfide gases from the well water, and further means (13) to vent the freed hydrogen sulfide gases to the atmosphere. The process for carrying out the invention comprises the steps of: pumping water under pressure from a well to a water delivery system, delivering a relatively small portion of water under pressure to the surface of the water in the well, causing turbulence in the well water to facilitate release of hydrogen sulfide gases from the well water, and venting the released hydrogen sulfide gases to the atmosphere.

  14. Noble gas detectors

    National Research Council Canada - National Science Library

    Aprile, Elena


    ... that is reflected in the high-quality discussions of principles and devices that will be found throughout the book. Noble gases in compressed or liquid form are regarded as an attractive detection medium from several standpoints. Detector volume is not limited by the need for crystal growth required in many alternative approaches, and the statistical limit on energy resolution is quite small due to moderate values for average ionization energy and a relatively low Fano factor. These media ...

  15. MASCOT: a new mass-spectrometer facility dedicated to the analysis of cosmogenic noble gases (3He and 21Ne) from terrestrial samples (Institute of Geological Sciences - University of Bern, Switzerland). (United States)

    Delunel, Romain; Enderli, Patrick; Jenni, Hans-Erich; Leya, Ingo; Schlunegger, Fritz


    In the past years, terrestrial cosmogenic nuclides have been successfully used for dating exposure history of landforms and measuring erosional processes on Earth's surface. In this context, quantifications of landscape change have mainly been accomplished through the use of radioactive cosmogenic nuclides such as 10Be and 26Al, but their application has generally been restricted to Quaternary time scales because of their relatively short half-lives. The results are 10Be and 26Al concentrations that are below the detection limit of available accelerator mass spectrometers if the samples have a Late Miocene or even a Pliocene age. Contrariwise, cosmogenic noble gases such as 3He and 21Ne do not experience any radioactive decay through time, which places these isotopes in an unbeatable position for measuring paleo-denudation rates preserved in detrital material even if the ages of these deposits are up to 10 Ma and even older. These isotopes are thus keys for assessing the interplays between tectonic, climate and surface processes involved in the long-term evolution of mountain belts. Here we report the technical specifications of a noble gas analytical system that we have developed and set up at the Institute of Geological Sciences of the University of Bern, Switzerland, with the motivations to get dates and rates of erosion processes from the measurement of cosmogenic noble gases (3He and 21Ne) concentrations from terrestrial samples. This new facility, hosted at the Institute of Geological Sciences of the University of Bern, combines a MAP215-50 mass spectrometer fitted with a new high-sensitivity channel electron multiplier with an all-metal extraction and purification line. This later system thus comprises: (i) a double vacuum resistance furnace loaded by a 22-samples carrousel, (ii) three in-vacuo crushers (iii) an ultra high vacuum pumping system (mass spectrometer. This communication will be the opportunity to present our new noble gas system's full

  16. Geochemical monitoring using noble gases and carbon isotopes: study of a natural reservoir; Monitoring geochimique par couplage entre les gaz rares et les isotopes du carbone: etude d'un reservoir naturel

    Energy Technology Data Exchange (ETDEWEB)

    Jeandel, E


    To limit emissions of greenhouse gases in the atmosphere, CO{sub 2} geological sequestration appears as a solution in the fight against climate change. The development of reliable monitoring tools to ensure the sustainability and the safety of geological storage is a prerequisite for the implementation of such sites. In this framework, a geochemical method using noble gas and carbon isotopes geochemistry has been tested on natural and industrial analogues. The study of natural analogues from different geological settings showed systematic behaviours of the geochemical parameters, depending on the containment sites, and proving the effectiveness of these tools in terms of leak detection and as tracers of the behaviour of CO{sub 2}. Moreover, an experience of geochemical tracing on a natural gas storage has demonstrated that it is possible to identify the physical-chemical processes taking place in the reservoir to a human time scale, increasing interest in the proposed tool and providing general information on its use. (author)

  17. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces. (United States)

    de Lara-Castells, María Pilar; Bartolomei, Massimiliano; Mitrushchenkov, Alexander O; Stoll, Hermann


    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = (3)He, (4)He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6-7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of

  18. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Castells, María Pilar de, E-mail:; Bartolomei, Massimiliano [Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid (Spain); Mitrushchenkov, Alexander O. [Laboratoire Modélisation et Simulation Multi Echelle, Université Paris-Est, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Stoll, Hermann [Institut für Theoretische Chemie, Universität Stuttgart, D-70550 Stuttgart (Germany)


    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = {sup 3}He, {sup 4}He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6–7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the

  19. Effect of the medium on intramolecular H-atom tunneling: cis-trans conversion of formic acid in solid matrixes of noble gases. (United States)

    Trakhtenberg, Leonid I; Fokeyev, Anatoly A; Zyubin, Alexander S; Mebel, Alexander M; Lin, S H


    Intramolecular tunneling of a hydrogen atom in formic acid at low temperatures has been studied theoretically on the basis of quantum-chemical modeling of HCOOH@Nb(12) clusters. Three noble matrixes (Ar, Kr, and Xe) are considered. Energetic and geometric parameters as well as vibrational frequencies for the formic acid in cis and trans configurations surrounded by 12 Nb atoms are calculated within the frame of the MP2 approach with extended basis sets. The rate constant of HCOOH cis-trans conversion is analyzed by taking into account matrix reorganization and the change of HCOOH position in the cluster. The matrix reorganization is considered within the Debye model of lattice vibrations, whereas the external motion of HCOOH in the cluster is treated using the Einstein model of solids. It has been shown that the literature experimental data on the cis to trans tunneling reaction in the formic acid can be accounted for within the proposed mechanism, which describes the matrix reorganization and the change of the HCOOH position in the noble gas matrix, with fitting parameters of the suggested theoretical model attaining reasonable values.

  20. Modified Lennard-Jones Potentials with a Reduced Temperature-Correction Parameter for Calculating Thermodynamic and Transport Properties: Noble Gases and Their Mixtures (He, Ne, Ar, Kr, and Xe

    Directory of Open Access Journals (Sweden)

    Seung-Kyo Oh


    Full Text Available The three-parameter Lennard-Jones (12-6 potential function is proposed to calculate thermodynamic property (second virial coefficient and transport properties (viscosity, thermal conductivity, and diffusion coefficient of noble gases (He, Ne, Ar, Kr, and Xe and their mixtures at low density. Empirical modification is made by introducing a reduced temperature-correction parameter τ to the Lennard-Jones potential function for this purpose. Potential parameters (σ, ε, and τ are determined individually for each species when the second virial coefficient and viscosity data are fitted together within the experimental uncertainties. Calculated thermodynamic and transport properties are compared with experimental data by using a single set of parameters. The present study yields parameter sets that have more physical significance than those of second virial coefficient methods and is more discriminative than the existing transport property methods in most cases of pure gases and of gas mixtures. In particular, the proposed model is proved with better results than those of the two-parameter Lennard-Jones (12-6 potential, Kihara Potential with group contribution concepts, and other existing methods.

  1. Noble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems (United States)

    Niu, Yi; Castro, M. Clara; Hall, Chris M.; Gingerich, Stephen B.; Scholl, Martha A.; Warrier, Rohit B.


    Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observed mean annual air temperature (MAAT) in sedimentary systems where infiltration is slower thus, providing information on recharge sources and potential flow paths. Here we report noble gas results from the basal aquifer, springs, and rainwater in Maui to explore the potential for noble gases in characterizing this type of complex fractured hydrologic systems. Most samples display a mass-dependent depletion pattern with respect to surface conditions consistent with previous observations both in the Galapagos Islands and Michigan rainwater. Basal aquifer and rainwater noble gas patterns are similar and suggest direct, fast recharge from precipitation to the basal aquifer. In contrast, multiple springs, representative of perched aquifers, display highly variable noble gas concentrations suggesting recharge from a variety of sources. The distinct noble gas patterns for the basal aquifer and springs suggest that basal and perched aquifers are separate entities. Maui rainwater displays high apparent NGTs, incompatible with surface conditions, pointing either to an origin at high altitudes with the presence of ice or an ice-like source of undetermined origin. Overall, noble gas signatures in Maui reflect the source of recharge rather than the expected altitude/temperature relationship commonly observed in sedimentary systems.

  2. Noble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems (United States)

    Niu, Yi; Castro, M. Clara; Hall, Chris M.; Gingerich, Stephen B.; Scholl, Martha A.; Warrier, Rohit B.


    Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observed mean annual air temperature (MAAT) in sedimentary systems where infiltration is slower thus, providing information on recharge sources and potential flow paths. Here we report noble gas results from the basal aquifer, springs, and rainwater in Maui to explore the potential for noble gases in characterizing this type of complex fractured hydrologic systems. Most samples display a mass-dependent depletion pattern with respect to surface conditions consistent with previous observations both in the Galapagos Islands and Michigan rainwater. Basal aquifer and rainwater noble gas patterns are similar and suggest direct, fast recharge from precipitation to the basal aquifer. In contrast, multiple springs, representative of perched aquifers, display highly variable noble gas concentrations suggesting recharge from a variety of sources. The distinct noble gas patterns for the basal aquifer and springs suggest that basal and perched aquifers are separate entities. Maui rainwater displays high apparent NGTs, incompatible with surface conditions, pointing either to an origin at high altitudes with the presence of ice or an ice-like source of undetermined origin. Overall, noble gas signatures in Maui reflect the source of recharge rather than the expected altitude/temperature relationship commonly observed in sedimentary systems.

  3. Radon: Not so Noble

    Indian Academy of Sciences (India)

    electronic configuration. [ 5S25p65d106s26p6]. Deepanjan Majumdar. Radon is a radioactive noble gas that occurs naturally but becomes an environmental hazard when it remains con- centrated in enclosed places .... public water supplies. Rivers carry .... relationship between cancer incidence and radon exposure has.

  4. Development of a portable membrane contactor sampler for noble gas analyses of surface and groundwater samples (United States)

    Matsumoto, T.; Han, L. H.; Jaklitsh, M.; Aggarwal, P. K.


    Noble gas isotopes dissolved in groundwater provide valuable information about climatic conditions during air-water exchange, as well as the residence time of groundwater and its renewal rate. The isotope composition of noble gases can also serve as geochemical fingerprints to decipher the origin of groundwater and its flow system. Conventionally, groundwater is sampled using a copper tube, which is subsequently degassed using a vacuum extraction system for isotope analysis by a mass spectrometer. Although this conventional and well-established way of sampling is widely recognised as being reliable and robust, a major drawback to this method is its size and weight. For example, our sampler consists of a copper tube of 10 mm diameter x 1000 mm length and a metal casing with pinch-off clamps with its total weight to be 2 kg each. A box of 24 samplers well exceeds 40 kg. Considering that sampling fields are not necessarily easily accessible by vehicle, taking hundreds of samples in the field is generally a tough task for everyone. There is a different type of sampler, which is comprised of a much smaller copper tube (6 mm in diameter and 100 mm long for our case) with clamps and a semi-permeable membrane filter. It is sunk into water and left there for dissolved gases to diffuse into the sampler until their concentrations in water become equilibrated with those in the tube. This diffusion sampler is small and easy to handle in the field; it has an advantage over conventional copper tubes, as the diffusion sampler collects gases so that there is no gas extraction process needed before isotope analysis. However, this method requires an equilibration time of 24 hours or more, which could result in lower time-efficiency for sampling work. In order to enable time-efficient and less-painstaking sampling of noble gases dissolved in surface and groundwater, we have developed a portable and self-powered sampling device specified to noble gas analysis by mass spectrometer

  5. Effective and selective extraction of noble metal nanoparticles from environmental water through a noncovalent reversible reaction on an ionic exchange resin. (United States)

    Li, Lingxiangyu; Leopold, Kerstin; Schuster, Michael


    Capable of preserving the size and shape of nanoparticles, a novel method to effectively and selectively extract noble metal nanoparticles even at the 80 ng L(-1) level from real environmental water was designed and performed using a noncovalent reversible adsorption onto an ionic exchange resin.

  6. σ-Aromatic cyclic M3(+) (M = Cu, Ag, Au) clusters and their complexation with dimethyl imidazol-2-ylidene, pyridine, isoxazole, furan, noble gases and carbon monoxide. (United States)

    Pan, Sudip; Saha, Ranajit; Mandal, Subhajit; Chattaraj, Pratim K


    The σ-aromaticity of M3(+) (M = Cu, Ag, Au) is analyzed and compared with that of Li3(+) and a prototype σ-aromatic system, H3(+). Ligands (L) like dimethyl imidazol-2-ylidene, pyridine, isoxazole and furan are employed to stabilize these monocationic M3(+) clusters. They all bind M3(+) with favorable interaction energy. Dimethyl imidazol-2-ylidene forms the strongest bond with M3(+) followed by pyridine, isoxazole and furan. Electrostatic contribution is considerably more than that of orbital contribution in these M-L bonds. The orbital interaction arises from both L → M σ donation and L ← M back donation. M3(+) clusters also bind noble gas atoms and carbon monoxide effectively. In general, among the studied systems Au3(+) binds a given L most strongly followed by Cu3(+) and Ag3(+). Computation of the nucleus-independent chemical shift (NICS) and its different extensions like the NICS-rate and NICS in-plane component vs. NICS out-of-plane component shows that the σ-aromaticity in L bound M3(+) increases compared to that of bare clusters. The aromaticity in pyridine, isoxazole and furan bound Au3(+) complexes is quite comparable with that in the recently synthesized Zn3(C5(CH3)5)3(+). The energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital also increases upon binding with L. The blue-shift and red-shift in the C-O stretching frequency of M3(CO)3(+) and M3(OC)3(+), respectively, are analyzed through reverse polarization of the σ- and π-orbitals of CO as well as the relative amount of OC → M σ donation and M → CO π back donation. The electron density analysis is also performed to gain further insight into the nature of interaction.

  7. Simultaneous Waste Heat and Water Recovery from Power Plant Flue Gases for Advanced Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dexin [Gas Technology Inst., Des Plaines, IL (United States)


    This final report presents the results of a two-year technology development project carried out by a team of participants sponsored by the Department of Energy (DOE). The objective of this project is to develop a membrane-based technology to recover both water and low grade heat from power plant flue gases. Part of the recovered high-purity water and energy can be used directly to replace plant boiler makeup water as well as improving its efficiency, and the remaining part of the recovered water can be used for Flue Gas Desulfurization (FGD), cooling tower water makeup or other plant uses. This advanced version Transport Membrane Condenser (TMC) with lower capital and operating costs can be applied to existing plants economically and can maximize waste heat and water recovery from future Advanced Energy System flue gases with CO2 capture in consideration, which will have higher moisture content that favors the TMC to achieve higher efficiency.

  8. Origin and age of thermal waters in Cieplice Spa, Sudeten, Poland, inferred from isotope, chemical and noble gas data (United States)

    Ciȩżkowski, W.; Gröning, M.; Leśniak, P. M.; Weise, S. M.; Zuber, A.


    Isotope and hydrochemical data of the thermal water system in Cieplice Ṡlaskie Zdrój (Spa) indicate the existence of two subsystems that greatly differ in volume and which meet at the fault zones of a granitic horst, where they discharge at an altitude of about 340m. One of the subsystems is very small (about 4 × 10 3 m 3) as indicated by the tritium age of the order of 10 years and a low outflow rate. Its recharge area found from the δ18O and δD values, is about 200m above the springs, most probably on the slopes of the foothills of the Karkonosze Mountains south-southwest of the spa. The large subsystem contains water which is free of tritium and whose 14C content is from 1 to 8 pmc with δ13C = -8.0 to -9.2‰. The isotopic composition of this water reflects either the climatic effect (low-altitude recharge during a cooler pre-Holocene climate) or the altitude effect (recharge in the early Holocene period at about 1000m at the heights of the Karkonosze assuming that the 14C concentration is strongly reduced by exchange with calcite in veins). For the former hypothesis, the recharge area of this water is probably either at the foot of the southeastern slopes of the Kaczawa Mountains or/and at the foot of the Rudawy Janowickie Mountains, to the east of Cieplice. The noble gas temperatures are more consistent with the pre-Holocene recharge. Similarly, the 4He excess and {40Ar}/{36Ar} ratio support the hypothesis of a pre-Holecene age. The constant {3He}/{4He} ratio of 26 × 10 -8 for highly different helium contents indicates crustal origin of helium. For the pre-Holocene age of water its volume is calculated at >- 10 9m 3 (stagnant water in micropores and mobile water in fractures) and the hydraulic conductivity of the host granite massif is estimated at about 7 × 10 -8 ms -1. Two outflows from this subsystem have different and variable fractions of a modern water component (bomb age), most probably originating from the bank infiltration of a nearby stream.

  9. Hydrogen from ethylene glycol by supercritical water reforming supported noble and base metal catalysts

    NARCIS (Netherlands)

    de Vlieger, Dennis; Chakinala, A.G.; Lefferts, Leonardus; Kersten, Sascha R.A.; Seshan, Kulathuiyer; Brilman, Derk Willem Frederik


    Catalytic reforming of ethylene glycol (5 and 15 wt%) in supercritical water (450 °C and 250 bar) in the presence of alumina supported mono- and bi-metallic catalysts based on Ir, Pt and Ni was studied. Pt catalyst showed the highest hydrogen yields compared to Ir and Ni. Varying the Pt loading

  10. Organ protection by the noble gas helium

    NARCIS (Netherlands)

    Smit, K.F.


    The aims of this thesis were to investigate whether helium induces preconditioning in humans, and to elucidate the mechanisms behind this possible protection. First, we collected data regarding organ protective effects of noble gases in general, and of helium in particular (chapters 1-3). In chapter

  11. Using Noble Gas Measurements to Derive Air-Sea Process Information and Predict Physical Gas Saturations (United States)

    Hamme, Roberta C.; Emerson, Steven R.; Severinghaus, Jeffrey P.; Long, Matthew C.; Yashayaev, Igor


    Dissolved gas distributions are important because they influence oceanic habitats and Earth's climate, yet competing controls by biology and physics make gas distributions challenging to predict. Bubble-mediated gas exchange, temperature change, and varying atmospheric pressure all push gases away from equilibrium. Here we use new noble gas measurements from the Labrador Sea to demonstrate a technique to quantify physical processes. Our analysis shows that water-mass formation can be represented by a quasi steady state in which bubble fluxes and cooling push gases away from equilibrium balanced by diffusive gas exchange forcing gases toward equilibrium. We quantify the rates of these physical processes from our measurements, allowing direct comparison to gas exchange parameterizations, and predict the physically driven saturation of other gases. This technique produces predictions that reasonably match N2/Ar observations and demonstrates that physical processes should force SF6 to be ˜6% more supersaturated than CFC-11 and CFC-12, impacting ventilation age calculations.

  12. Simultaneous treatment of SO2 containing stack gases and waste water (United States)

    Poradek, J. C.; Collins, D. D. (Inventor)


    A process for simultaneously removing sulfur dioxide from stack gases and the like and purifying waste water such as derived from domestic sewage is described. A portion of the gas stream and a portion of the waste water, the latter containing dissolved iron and having an acidic pH, are contacted in a closed loop gas-liquid scrubbing zone to effect absorption of the sulfur dioxide into the waste water. A second portion of the gas stream and a second portion of the waste water are controlled in an open loop gas-liquid scrubbing zone. The second portion of the waste water contains a lesser amount of iron than the first portion of the waste water. Contacting in the openloop scrubbing zone is sufficient to acidify the waste water which is then treated to remove solids originally present.

  13. Isotopic and noble gas geochemistry in geothermal research

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, B.M.; DePaolo, D.J. [Lawrence Berkeley National Lab., CA (United States)


    The objective of this program is to provide, through isotopic analyses of fluids, fluid inclusions, and rocks and minerals coupled with improved methods for geochemical data analysis, needed information regarding sources of geothermal heat and fluids, the spatial distribution of fluid types, subsurface flow, water-rock reaction paths and rates, and the temporal evolution of geothermal systems. Isotopic studies of geothermal fluids have previously been limited to the light stable isotopes of H, C, and O. However, other isotopic systems such as the noble gases (He, Ne, Ar, Kr and Xe) and reactive elements (e.g. B, N, S, Sr and Pb) are complementary and may even be more important in some geothermal systems. The chemistry and isotopic composition of a fluid moving through the crust will change in space and time in response to varying chemical and physical parameters or by mixing with additional fluids. The chemically inert noble gases often see through these variations, making them excellent tracers for heat and fluid sources. Whereas, the isotopic compositions of reactive elements are useful tools in characterizing water-rock interaction and modeling the movement of fluids through a geothermal reservoir.

  14. A comparative summary on streamers of positive corona discharges in water and atmospheric pressure gases (United States)

    Tachibana, Kunihide; Motomura, Hideki


    From an intention of summarizing present understandings of positive corona discharges in water and atmospheric pressure gases, we tried to observe streamers in those media by reproducing and complementing previously reported results under a common experimental setup. We used a point-to-plane electrode configuration with different combinations of electrode gap (7 and 19 mm length) and pulsed power sources (0.25 and 2.5 ɛs duration). The general features of streamers were similar and the streamer-to-spark transition was also observed in both the media. However, in the details large differences were observed due to inherent nature of the media. The measured propagation speed of streamers in water of 0.035 × 106 ms-1 was much smaller than the speed in gases (air, N2 and Ar) from 0.4 to 1.1 × 106 ms-1 depending on species. In He the discharge looked glow-like and no streamer was observed. The other characteristics of streamers in gases, such as inception voltage, number of branches and thickness did also depend on the species. The thickness and the length of streamers in water were smaller than those in gases. From the volumetric expansion of a streamer in water after the discharge, the molecular density within the streamer medium was estimated to be rarefied from the density of water by about an order of magnitude in the active discharge phase. We derived also the electron density from the analysis of Stark broadened spectral lines of H and O atoms on the order of 1025 m-3 at the earlier time of the streamer propagation. The analyzed background blackbody radiation, rotational temperature of OH band emission and population density of Cu atomic lines yielded a consistent temperature of the streamer medium between 7000 and 10 000 K. Using the present data with a combination of the analysis of static electric field and previously reported results, we discuss the reason for the relatively low streamer inception voltage in water as compared to the large difference in the

  15. Facile synthesis of reduced graphene oxide films at the air-water interface and in situ loading of noble metal nanoparticles (United States)

    Bramhaiah, K.; John, Neena S.


    Transparent free-standing films of reduced graphene oxide (RGO) are obtained from graphene oxide solution at the air-water interface in a simple, rapid, one-step reduction process with tetrakis(hydroxymethyl)phosphonium chloride (THPC), a widely used reducing agent for synthesizing metal nanoparticles from metal salts. The thickness of the films depends on the initial concentration of graphene oxide (GO). The restoration of the aromatic basal plane network and the removal of oxygen groups are confirmed by UV-visible and infrared spectroscopies. Atomic force microscopy shows that the film consists of a self-assembled monolayer of RGO platelets that are continuous over micrometre scale areas. In the presence of noble metal ions, THPC reduces both GO and metal ions to form free-standing films of RGO decorated by noble metal nanoparticles. Compared to other reported methods, the THPC route offers a very rapid and one-step process to obtain ultra-thin films of RGO loaded with noble metal nanoparticles.

  16. Noble gases in ancient asteroidal atmospheres (United States)

    Swindle, Timothy D.


    Analytical and numerical results presented here suggest that acceleration of photoions by the solar wind motional field is a significant loss process for Xe on asteroids about 200 km in radius or larger, if the Xe is thermalized by its interactions with the surface. For Ar, photoion acceleration can only become important for asteroids nearly 500 km in radius. Thus photoion acceleration, previously invoked for lunar samples, could be responsible for excess fission-produced Xe found associated with solar wind Xe in howarditic meteorites. The lack of such Xe in other types of meteorites may reflect either smaller parent bodies or later times of regolith exposure. Similarly, the failure to observe solar-wind-associated radiogenic Ar-40 in meteorites is consistent with the much smaller likelihood that Ar will be photoionized.


    Directory of Open Access Journals (Sweden)

    G. Ya. Akhmedov


    Full Text Available Objectives. The aim of the study is to assess the appropriateness of utilising combustible gases associated with geothermal water with  low gas factor and the possibility of its practical implementation with  the provision of power equipment operation of geothermal systems  with a nonscaling mode.Methods. The investigations were carried out by analysing the content of associated combustible gases in the underground  thermomineral waters of the Cis-Caucasian deposits on the basis of  an assessment of the feasibility of their utilisation for heating and  hot water supply.Results. A review of practically existing heat and power schemes  utilising geothermal water sources is carried out. Based on the  studies conducted, it is found that methane (70-90% is prevalent in the water under consideration; meanwhile, the content of heavy hydrocarbons does not exceed 10%. The concentration of carbon  dioxide is 3 ÷ 6%, nitrogen 1 ÷ 4%. Depending on the depth of the  aquifer, gas factors range from 1 to 5 m3/ m3. As a result of the  analysis of the operation of typical thermal distribution stations, it is  established that a violation of the carbon dioxide equilibrium in water leads to the formation of a solid phase of calcium carbonate on the  heat exchange surface. A technique for estimating the relationship between the partial pressure of methane and carbon dioxide with the total pressure in a solution of geothermal water is proposed. A  scheme for the efficient operation of thermal distribution stations  with the prevention of carbonate deposits formation by using the  combustion products of the used gas combined with the injection of waste water back into the aquifer is presented.Conclusion. As a result of the conducted studies, the possibility of  using associated combustible gases in geothermal wells is  established using differences in their solubility and that of carbon  dioxide. In this case, the protection of

  18. Weak interactions between water and clathrate-forming gases at low pressures

    Energy Technology Data Exchange (ETDEWEB)

    Thurmer, Konrad; Yuan, Chunqing; Kimmel, Gregory A.; Kay, Bruce D.; Smith, R. Scott


    Using scanning probe microscopy and temperature programed desorption we examined the interaction between water and two common clathrate-forming gases, methane and isobutane, at low temperature and low pressure. Water co-deposited with up to 10-1 mbar methane or 10-5 mbar isobutane at 140 K onto a Pt(111) substrate yielded pure crystalline ice, i.e., the exposure to up to ~107 gas molecules for each deposited water molecule did not have any detectable effect on the growing films. Exposing metastable, less than 2 molecular layers thick, water films to 10-5 mbar methane does not alter their morphology, suggesting that the presence of the Pt(111) surface is not a strong driver for hydrate formation. This weak water-gas interaction at low pressures is supported by our thermal desorption measurements from amorphous solid water and crystalline ice where 1 ML of methane desorbs near ~43 K and isobutane desorbs near ~100 K. Similar desorption temperatures were observed for desorption from amorphous solid water.

  19. Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Chao, K.C.


    Phase equilibrium in mixtures of water + light gases and water + heavy hydrocarbons has been investigated with the development of new local composition theory, new equations of state, and new experimental data. The preferential segregation and orientation of molecules due to different energies of molecular interaction has been simulated with square well molecules. Extensive simulation has been made for pure square well fluids and mixtures to find the local composition at wide ranges of states. A theory of local composition has been developed and an equation of state has been obtained for square well fluids. The new local composition theory has been embedded in several equations of state. The pressure of water is decoupled into a polar pressure and non-polar pressure according to the molecular model of water of Jorgensen et al. The polar pressure of water is combined with the BACK equation for the general description of polar fluids and their mixtures. Being derived from the steam table, the Augmented BACK equation is particularly suited for mixtures of water + non-polar substances such as the hydrocarbons. The hydrophobic character of the hydrocarbons had made their mixtures with water a special challenge. A new group contribution equation of state is developed to describe phase equilibrium and volumetric behavior of fluids while requiring only to know the molecular structure of the components. 15 refs., 1 fig.

  20. Improving the efficiency of water purification from dissolved gases at TPP (United States)

    Laptev, A. G.; Lapteva, E. A.; Shagieva, G. K.


    The method for increasing the efficiency of thermal deaerators and calciners of a TPP is considered; it consists of the use of a turbulent mass transfer device with random small packing. Before entering the packed bed in water, air (decarbonization) or water vapor (deaeration) is supplied. Chaotic nozzle creates intense turbulent interaction mode of air (vapor) with water and splitting it into small bubbles; thus the specific surface area of the contact of phases significantly increases, and high efficiency of mass transfer (extraction of dissolved gases) is ensured. A turbulent mass transfer device is a circular channel with connections for connecting of the source water to a pipeline. Inzhekhim chaotic nozzle is used with large free volume (95%) and the specific surface area of 150-300 m2/m3. The nozzle is made of a thin metal strip that may have a rough surface and is retained in the channel by means of two grids. For the calculation of turbulent mixer, mathematical model of the flow structure is presented, which is built with the use of a one-parameter diffusion model and a semiempirical reverse mixing ratio. Accounting of interphase transfer of dissolved gases is carried out via volume source of weight. The equation to determine the weight source and calculation of its parameters is presented. In the particular case, transition to the cell model is made and an expression for calculating the profile of concentrations of dissolved gas is obtained along the channel with a nozzle. An example of calculating the efficiency of turbulent mixer upon removing dissolved carbon dioxide from water at a TPP is shown. Recommendations on the use of the considered technical device are given.

  1. Noble gas partitioning behavior in the Sleipner Vest hydrocarbon field (United States)

    Barry, P. H.; Lawson, M.; Warr, O.; Mabry, J.; Byrne, D. J.; Meurer, W. P.; Ballentine, C. J.


    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways, mechanisms and reservoir storage. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. We present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner gases are generated from primary cracking of kerogen and the thermal cracking of oil, sourced from type II marine source, with relatively homogeneous maturities and a range in vitrinite reflectance (1.2-1.7%). Gases are hosted in the lower shoreface sandstones of the Jurassic Hugin formation, which is sealed by the Jurassic Upper Draupne and Heather formations. Gases are composed of N2 (0.6-0.9%), CO2 (5.4-15.3%) and hydrocarbons (69-80%). Helium isotopes (3He/4He) are radiogenic and range from 0.065 to 0.116 RA, showing a small mantle contribution, consistent with Ne isotopes (20Ne/22Ne from 9.70-9.91; 21Ne/22Ne from 0.0290-0.0344) and Ar isotopes (40Ar/36Ar from 315-489). 20Ne/36Ar, 84Kr/36Ar and 132Xe/36Ar values are systematically higher relative to air saturated water ratios. These data are discussed within the framework of several conceptual models: i) Total gas-stripping model, which defines the minimum volume of water to have interacted with the hydrocarbon phase; ii) Equilibrium model, assuming simple equilibration between groundwater and hydrocarbon phase at reservoir P,T and salinity; and iii) Open and closed system gas-stripping models. Using Ne-Ar, we estimate gas-water ratios for the Sleipner system of 0.02-0.09, which compare with geologic gas-water estimates of ~0.24, and suggest more groundwater interaction than a static system estimate. Kr and Xe show evidence for an additional source or process involving oil or sediments.

  2. Geochemical studies of rocks, water, and gases at Mt. Hood, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, H.A.; Bowen, R.E.; Bowman, H.R.; Strisower, B.


    Mr. Hood, a composite andesitic volcano, located near Portland, Oregon, is one of several large eruptive centers which dominate the Cascade Mountains of the western United States. As part of a program of geologic, geophysical and geochemical studies to examine Mt. Hood's geothermal resource potential, samples of warm-and cold-spring water, water from a geothermal test well in Old Maid Flat, fumarolic gases, and rocks were collected and analyzed for major chemical constituents and trace elements. The only warm-spring area on Mt. Hood is Swim Springs, located on the south flank. Orifices at Swim were sampled repeatedly with little overall change noted in water chemistry between summer and winter. Oxygen and hydrogen isotope data and mixing calculations based on analyses of Swim Springs and numerous cold springs, indicate that a large component of the warm water at Swim is from near-surface runoff. Chemical geothermometry suggests that temperatures at depth in the Swim Springs system are within the range 104 to 170/sup 0/C; the temperature of unmixed hot water may exceed 200/sup 0/C. Higher-than-background chloride contents and specific conductances of cold springs on the south flank of the mountain suggest that there is a small component of thermal water in these sources. A geothermal model of Mt. Hood is proposed wherein snow- and glacier-melt water near the summit comes in close promimity to the hot central neck of the mountain, manifested by the summit-crater fumaroles.Iridium was detected in warm and cold spring waters and in a sample of altered andesite.

  3. Catalytic combustion of actual low and medium heating value gases (United States)

    Bulzan, D. L.


    Catalytic combustion of both low and medium heating value gases using actual coal derived gases obtained from operating gasifiers was demonstrated. A fixed bed gasifier with a complete product gas cleanup system was operated in an air blown mode to produce low heating value gas. A fluidized bed gasifier with a water quench product gas cleanup system was operated in both an air enriched and an oxygen blown mode to produce low and medium, heating value gas. Noble metal catalytic reactors were evaluated in 12 cm flow diameter test rigs on both low and medium heating value gases. Combustion efficiencies greater than 99.5% were obtained with all coal derived gaseous fuels. The NOx emissions ranged from 0.2 to 4 g NO2 kg fuel.

  4. Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water. (United States)

    Cadena-Pereda, Raúl O; Rivera-Muñoz, Eric M; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J; Anaya-Rivera, Ely K


    Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0-100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

  5. Automatic Carbon Dioxide-Methane Gas Sensor Based on the Solubility of Gases in Water

    Directory of Open Access Journals (Sweden)

    Raúl O. Cadena-Pereda


    Full Text Available Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0–100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

  6. Methane Sources and Migration Mechanisms in the Shallow Trinity Aquifer in Parker and Hood Counties, Texas - a Noble Gas Analysis (United States)

    Wen, T.; Castro, C.; Nicot, J. P.; Hall, C. M.; Mickler, P. J.; Darvari, R.


    The presence of elevated methane in groundwaters within the Barnett Shale footprint in Parker and Hood counties, Texas has caused public concern that hydrocarbon production may facilitate migration of natural gas into a critical groundwater resource. This study places constraints on the source of methane in these groundwaters by analyzing water and stray gas data from groundwater wells and gas production wells from both the Barnett Shale and Strawn Group for methane content and noble gases, both of crustal and atmospheric origin. Particular emphasis is given to the atmospheric heavier noble gases 84Kr and 132Xe, which are significantly less affected by the presence of excess air, commonly present in modern Texas groundwaters (e.g., [1]). Dissolved methane concentrations are positively correlated with crustal 4He, 21Ne and 40Ar and suggest that noble gases and methane in these groundwaters originate from a common source, likely the Strawn Group, which the sampled aquifer overlies unconformably. This finding is further supported by the noble gas isotopic signature of stray gas when compared to the gas isotopic signatures of both Barnett Shale and the Strawn Group. In contrast to most samples, four groundwater wells with the highest methane concentrations unequivocally show heavy depletion of the atmospheric noble gases 20Ne, 36Ar, 84Kr and 132Xe with respect to freshwater recharge equilibrated with the atmosphere (ASW). This is consistent with predicted noble gas concentrations in a residual water phase in contact with a gas phase with initial ASW composition at 18°C-25°C, assuming a closed-system and suggest a highly localized gas source. All these four wells, without exception, tap into the Strawn Group and it is likely that shallow gas accumulations, as they are known to exist, were reached. Additionally, lack of correlation between 84Kr/36Ar and 132Xe/36Ar fractionation levels and distance to the nearest production wells does not support the notion that methane

  7. The noble gas geochemistry of natural CO 2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA (United States)

    Gilfillan, Stuart M. V.; Ballentine, Chris J.; Holland, Greg; Blagburn, Dave; Lollar, Barbara Sherwood; Stevens, Scott; Schoell, Martin; Cassidy, Martin


    Identification of the source of CO 2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO 2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO 2 in the subsurface. We present the results of 57 noble gas determinations in CO 2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John's Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO 2/ 3He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO 2 can be stored within the subsurface on a millennia timescale. The manner and extent of contact of the CO 2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO 2. We show that coherent fractionation of groundwater 20Ne/ 36Ar with crustal radiogenic noble gases ( 4He, 21Ne, 40Ar) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO 2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO 2/water phase partitioning. The CO 2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO 2 provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO 2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO 2 filling direction. This is seen in the Bravo Dome

  8. Geochemical Data on Waters, gases, scales, and rocks from the Dixie Valley Region, Nevada (1996-1999)

    Energy Technology Data Exchange (ETDEWEB)

    Goff, Fraser; Bergfeld, Deborah; Janik, C.J.; et al


    This report tabulates an extensive geochemical database on waters, gases, scales, rocks, and hot-spring deposits from the Dixie Valley region, Nevada. The samples from which the data were obtained were collected and analyzed during 1996 to 1999. These data provide useful information for ongoing and future investigations on geothermal energy, volcanism, ore deposits, environmental issues, and groundwater quality in this region.

  9. A Geochemical Approach for Monitoring a CO2 Pilot Site: Rousse, France. A Major gases, CO2-Carbon Isotopes and Noble Gases Combined Approach Une méthode géochimique pour la surveillance d’un site pilote de stockage de CO2 : Rousse, France. Approche combinant les gaz majeurs, l’isotopie du carbone du CO2 et les gaz rares

    Directory of Open Access Journals (Sweden)

    Garcia B.


    Full Text Available This paper presents the geochemical characterization of various gas end-members involved in a depleted gas field CO2 storage pilot (Rousse, France. In this pilot, CO2 is produced by oxycombustion from natural gas transformed into fuel gas at the Lacq plant, and transported in a pipeline 30 km away to the depleted gas reservoir of Rousse. Gases produced at Rousse before CO2 injection, the Lacq fuel gas and the CO2 resulting from the oxy-fuel combustion were sampled, together with gases from a –45 m monitoring well and from soils in the vicinity of the Rousse structure. For all samples, the bulk gas composition, the carbon isotopic compositions and the abundance and isotopic signatures of the noble gases were determined. The bulk gas compositions of the Rousse natural gas are comparable to the Lacq fuel gas with methane as the main compound with residual C2-C5 and CO2. Soil gases are typical mixtures of air with biogenic CO2 (up to 9-10%, while the monitoring well gases display typical air compositions with no excess CO2 The Rousse gas and the Lacq fuel gas have δ13CCH4 values of –41.0‰ and –43.0‰ respectively. The injected CO2 out of the oxycombustion chamber has a δ13CCO2 of –40.0‰, whereas δ13CCO2 value for soils samples is comprised between –15 and –25‰. The Rousse natural gas and the Lacq fuel gas are both characterized by a high He enrichment, and depletion in Ne, Ar and Kr compared to the air values. The oxyfuel combustion process provides a CO2 with the He enrichment of the Lacq fuel gas, and a Ne, Ar and Kr composition reflecting that of the oxygen produced at the Air Separation Unit (ASU. Indeed, Ne is depleted relatively to the air, while Kr is enriched up to tenfold, which results from the cryogenic separation of the air noble gases within the ASU. Soil samples noble gas compositions are equivalent to that of the air. In the light of these results, the compositions of the various end-members involved in this CO2

  10. [Effects of antiseptic on the analysis of greenhouse gases concentrations in lake water]. (United States)

    Xiao, Qi-Tao; Hu, Zheng-Hu; James, Deng; Xiao, Wei; Liu, Shou-Dong; Li, Xu-Hui


    To gain insight into antiseptic effects on the concentrations of CO2, CH4, and N2O in lake water, antisepetic (CuSO4 and HgCl2) were added into water sample, and concentrations of greenhouse gases were measured by the gas chromatography based on water equilibrium method. Experiments were conducted as following: the control group without antisepetic (CK), the treatment group with 1 mL CuSO4 solution (T1), the treatment group with 5 mL CuSO4 solution (T2), and the treatment group with 0.5 mL HgCl2 solution (T3). All groups were divided into two batches: immediately analysis (I), and after 2 days analysis (II). Results showed that CuSO4 and HgCl2 significantly increased CO2 concentration, the mean CO2 concentration (Mco2) of CK (I) and CK (II) were (11.5 +/- 1.47) micromol x L(-1) and (14.38 +/- 1.59) micromol x L(-1), respectively; the Mco2 of T1 (I) and T1 (II) were (376 +/- 70) micromol x L(-1) and (448 +/- 246.83) micromol x L(-1), respectively; the Mco2 of T2 (I) and T2 (II) were (885 +/- 51.53) micromol x L(-1) and (988.83 +/- 101.96) micromol x L(-1), respectively; the Mco2 of T3 (I) and T3 (II) were (287.19 +/- 30.01) micromol x L(-1) and (331.33 +/- 22.06) micromol x L(-1), respectively. The results also showed that there was no difference in CH4 and N2O concentrations among treatments. Water samples should be analyzed as soon as possible after pretreatment. Our findings suggest that adding antiseptic may lead an increase in CO2 concentration.

  11. Consistent measurements comparing the drift features of noble gas mixtures

    CERN Document Server

    Becker, U; Fortunato, E M; Kirchner, J; Rosera, K; Uchida, Y


    We present a consistent set of measurements of electron drift velocities and Lorentz deflection angles for all noble gases with methane and ethane as quenchers in magnetic fields up to 0.8 T. Empirical descriptions are also presented. Details on the World Wide Web allow for guided design and optimization of future detectors.

  12. Adsorption of water and ethanol on noble and transition-metal substrates: a density functional investigation within van der Waals corrections. (United States)

    Freire, Rafael L H; Kiejna, Adam; Da Silva, Juarez L F


    We report the results of extensive computational investigation of the adsorption properties of water and ethanol on several Cu-, Pt-, and Au-based substrates, including the close-packed unreconstructed Cu(111), Pt(111), and Au(111) surfaces, defected metal substrates with on-surface low-coordinated sites generated by the intermixing of Pt-Cu and Pt-Au in the topmost surface layers and strained on-surface and sub-surface Pt-layers at Cu(111) and Au(111) substrates. The calculations are based on the density functional theory (DFT) within the van der Waals (vdW) correction. For all the substrates, we found that water and ethanol bind via the anionic O atom to the cationic one-fold coordinated on-top metal sites, which enhances the adsorbate-substrate Coulomb interactions. For water, both DFT and DFT + vdW calculations predict a flat geometry. For ethanol, the DFT and DFT + vdW results are in contrast, namely, DFT yields a perpendicular orientation of the C-C bond with respect to the surface, while we obtained a parallel orientation of the C-C bond using DFT + vdW, which maximizes the adsorption energies. Despite expected deviations due to the nature of the weak adsorbate-substrate interactions, we found that the adsorption energy of water and ethanol shows a linear dependence as a function of the position of the center of gravity of the occupied d-band, and hence, the magnitude of the adsorption energy increases as the d-band center position shifts towards the Fermi energy. Thus, it indicates hybridization between the O p- and metal d-states, which determines the magnitude of the adsorption energy of water and ethanol on clean, low-coordinated, and strained noble and transition-metal substrates.

  13. Influence of water vapour and permanent gases on the atmospheric optical depths and transmittance (United States)

    Badescu, V.


    The influence of the atmospheric state on the extinction of direct solar radiation has been studied by using a four layer atmospheric model. Simple analytical formulae are established for the spectral optical depths of permanent gases and water vapour. These formulae use the ground level values of air pressure, temperature and relative huniidity. An additional parameter, related to the vertical distribution of the hunmidity content, is used for a better estimation of the water vapour optical depth. Good agreement between theory and measurements is found. The paper shows the dependence of the atmospheric spectral transmittance on the above mentioned parameters. L'influence de l'état atmosphérique sur l'extinction de la radiation solaire directe a été étudiée à l'aide d'un modèle atmosphérique développé antérieurement par l'auteur. Des formules simples ont été établies pour l'épaisseur optique spectrale des gaz et de la vapeur d'eau. Ces formules utilisent les valeurs de la pression atmosphérique, de la température et de l'humidité relative, mesurées au niveau du sol. Un paramètre supplémentaire, lié à la distribution verticale du contenu d'humidité, est utilisé pour calculer l'épaisseur optique due à la vapeur d'eau. La théorie est en bon accord avec les résultats des mesures. Le travail montre la dépendance de la transmittance atmosphérique spectrale en fonction des paramètres spécifiés ci-dessus.

  14. Method of reducing environmental pollution by utilizing stack gases, resulting from the burning of fossil fuels, and water, including sea water and waste water, to manufacture hydrocarbon energy fuel, potable water and other commercial products. [processing of flue gases and seawater or waste water to produce methane and useful by-products

    Energy Technology Data Exchange (ETDEWEB)

    New, R.V.


    A method and apparatus is described for treating smoke stack gases diverted to minimize air pollution to recover from the stack gases the individual constituents thereof, namely, carbon dioxide (CO/sub 2/), water (H/sub 2/O) and nitrogen (N/sub 2/) freed of other products, such as oxides; and to recover from water (including nonpotable water such as sea water, waste water and even polluted water sources) the individual constituents thereof of interest here, namely, hydrogen (H/sub 2/); and delivering the recovered carbon dioxide and the recovered hydrogen into a catalytic reaction chamber under sufficiently high temperature conditions in the presence of a suitable catalyst to establish therein a reaction temperature to support a Sabatier catalytic reaction (CO/sub 2/ + 4H/sub 2/ = CH/sub 4/ + 2H/sub 2/O) hydrogenating the carbon dioxide to form methane for use as fuel, and potable water for commercial usage. (Official Gazette)

  15. Greenhouse Gases (United States)

    ... atmosphere, creating a greenhouse effect that results in global warming and climate change. Many gases exhibit these greenhouse properties. Some gases occur naturally and are also produced by human activities. Some, such as industrial gases, are exclusively ...

  16. A noble gas palaeotemperature record from the Ledo-Paniselian aquifer in Belgium (United States)

    Aeschbach-Hertig, W.; Kipfer, R.; Blaser, P.; Walraevens, K.


    The Ledo-Paniselian sands form a confined coastal aquifer, extending from north-western Belgium (Flanders) towards the Netherlands. An extensive record of noble gas temperatures (NGTs) from this aquifer indicates strong glacial cooling. While Holocene samples yield NGTs of 8 to 10 ^oC, in agreement with modern air temperatures, NGTs near the freezing point (ages requires careful consideration of the geochemical and isotopic data. The systematic evolution of water chemistry in this freshening aquifer has been described before and was used to cross-check and correct the dating by taking into account chemical reactions and isotope exchange. The large noble gas data set (44 samples from 39 wells) encourages a systematical study of the factors affecting the composition of dissolved noble gases in groundwater. Some samples show a clear degassing pattern, which was reproduced in a few wells that were sampled both in 1998 and 2001. This finding indicates that degassing is not an artefact of sampling. We discuss possibilities to model the effect of degassing in order to derive reliable NGTs from these samples.

  17. Processes of noble gas elemental and isotopic fractionations in plasma-produced organic solids: Cosmochemical implications (United States)

    Kuga, Maïa; Cernogora, Guy; Marrocchi, Yves; Tissandier, Laurent; Marty, Bernard


    The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. The Q noble gas component shows elemental and isotopic fractionation relative to the Solar, in favor of heavy elements and isotopes. These noble gas characteristics were experimentally simulated using a plasma device called the ;Nebulotron;. In this study, we synthesized thirteen solid organic samples by electron-dissociation of CO, in which a noble gas mixture was added. The analysis of their heavy noble gas (Ar, Kr and Xe) contents and isotopic compositions reveals enrichment in the heavy noble gas isotopes and elements relative to the light ones. The isotope fractionation is mass-dependent and is consistent with a mn-type law, where n ≥ 1. Based on a plasma model, we propose that the ambipolar diffusion of ions in the ionized CO gas medium is at the origin of the noble gas isotopic fractionation. In addition, the elemental fractionation of experimental and chondritic samples can be accounted for by the Saha law of plasma equilibrium, which does not depend on the respective noble gas masses but rather on their ionization potentials. Our results suggest that the Q noble gases were trapped into growing organic particles starting from solar gases that were fractionated in an ionized medium by ambipolar diffusion and Saha processes. This would imply that both the formation of chondritic organic matter and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk.

  18. Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, I.; Huppert, M.; Wörner, H. J., E-mail: [Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich (Switzerland); Brown, M. A. [Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich (Switzerland); Bokhoven, J. A. van [Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich (Switzerland); Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, 5232 Villigen (Switzerland)


    A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

  19. Radon: Not so Noble

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 7. Radon: Not so Noble-Radon in the Environment and Associated Health Problems. Deepanjan Majumdar. General Article Volume 5 Issue 7 July 2000 pp 44-55. Fulltext. Click here to view fulltext PDF. Permanent link:

  20. Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting (United States)

    Wang, Haotian; Lee, Hyun-Wook; Deng, Yong; Lu, Zhiyi; Hsu, Po-Chun; Liu, Yayuan; Lin, Dingchang; Cui, Yi


    Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (∼20 nm) are electrochemically transformed into ultra-small diameter (2–5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm−2 water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts. PMID:26099250

  1. Highly stable noble metal nanoparticles dispersible in biocompatible solvents: synthesis of cationic phosphonium gold nanoparticles in water and DMSO. (United States)

    Ju-Nam, Yon; Abdussalam-Mohammed, Wanisa; Ojeda, Jesus J


    In this work, we report the synthesis of novel cationic phosphonium gold nanoparticles dispersible in water and dimethyl sulfoxide (DMSO) for their potential use in biomedical applications. All the cationic-functionalising ligands currently reported in the literature are ammonium-based species. Here, the synthesis and characterisation of an alternative system, based on phosphonioalkylthiosulfate zwitterions and phosphonioalkylthioacetate were carried out. We have also demonstrated that our phosphonioalkylthiosulfate zwitterions readily disproportionate into phosphonioalkylthiolates in situ during the synthesis of gold nanoparticles produced by the borohydride reduction of gold(III) salts. The synthesis of the cationic gold nanoparticles using these phosphonium ligands was carried out in water and DMSO. UV-visible spectroscopic and TEM studies have shown that the phosphonioalkylthiolates bind to the surface of gold nanoparticles which are typically around 10 nm in diameter. The resulting cationic-functionalised gold nanoparticles are dispersible in aqueous media and in DMSO, which is the only organic solvent approved by the U.S. Food and Drug Administration (FDA) for drug carrier tests. This indicates their potential future use in biological applications. This work shows the synthesis of a new family of phosphonium-based ligands, which behave as cationic masked thiolate ligands in the functionalisation of gold nanoparticles. These highly stable colloidal cationic phosphonium gold nanoparticles dispersed in water and DMSO can offer a great opportunity for the design of novel biorecognition and drug delivery systems.

  2. Element distribution and noble gas isotopic abundances in lunar meteorite Allan Hills A81005 (United States)

    Kraehenbuehl, U.; Eugster, O.; Niedermann, S.


    Antarctic meteorite ALLAN HILLS A81005, an anorthositic breccia, is recognized to be of lunar origin. The noble gases in this meteorite were analyzed and found to be solar-wind implanted gases, whose absolute and relative concentrations are quite similar to those in lunar regolith samples. A sample of this meteorite was obtained for the analysis of the noble gas isotopes, including Kr(81), and for the determination of the elemental abundances. In order to better determine the volume derived from the surface correlated gases, grain size fractions were prepared. The results of the instrumental measurements of the gamma radiation are listed. From the amounts of cosmic ray produced noble gases and respective production rates, the lunar surface residence times were calculated. It was concluded that the lunar surface time is about half a billion years.

  3. Noble Gas Detectors

    CERN Document Server

    Aprile, Elena; Bolozdynya, Alexander I; Doke, Tadayoshi


    This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc.The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation

  4. Optical propagation in linear media atmospheric gases and particles, solid-state components, and water

    CERN Document Server

    Thomas, Michael E


    PART I: Background Theory and Measurement. 1. Optical Electromagnetics I. 2. Optical Electromagnetics II. 3. Spectroscopy of Matter. 4. Electrodynamics I: Macroscopic Interaction of Light and Matter. 5. Electrodynamics II: Microscopic Interaction of Light and Matter. 6. Experimental Techniques. PART II: Practical Models for Various Media. 7. Optical Propagation in Gases and the Atmosphere of the Earth. 8. Optical Propagation in Solids. 9. Optical Propagation in Liquids. 10. Particle Absorption and Scatter. 11. Propagation Background and Noise

  5. Gases in molten salts

    CERN Document Server

    Tomkins, RPT


    This volume contains tabulated collections and critical evaluations of original data for the solubility of gases in molten salts, gathered from chemical literature through to the end of 1989. Within the volume, material is arranged according to the individual gas. The gases include hydrogen halides, inert gases, oxygen, nitrogen, hydrogen, carbon dioxide, water vapor and halogens. The molten salts consist of single salts, binary mixtures and multicomponent systems. Included also, is a special section on the solubility of gases in molten silicate systems, focussing on slags and fluxes.

  6. Infrared scintillation in gases, liquids and crystals

    NARCIS (Netherlands)

    Belogurov, S.; Bressi, G; Carugno, G.; Conti, E; Iannuzzi, D; Meneguzzo, AT


    We report about experimental evidences of infrared scintillation in gaseous, liquid and crystal samples. We firstly studied noble gases at room temperature and near atmospheric pressure in the wavelength range between 0.7 and 1.81 mum. Ar gas emits infrared photons when irradiated by a proton beam.

  7. Fullerenes and the Nature of Planetary Gases (United States)

    Becker, Luann; Poreda, Robert J.; Nuth, Joe


    Over the past several decades, two issues have dominated the discussion of planetary noble gas patterns: 1) the general resemblance of the noble gas abundances in carbonaceous chondrites to those measured in the Earth s atmosphere and; 2) atmospheric inventories of argon and neon that fall off significantly with increasing distance from the Sun. The recognition of the latter has led to the conclusion that the planetary component is not found on planets. In particular, the inability to explain the missing xenon reservoir, once thought to be sequestered in crustal rocks has been extremely troublesome. Some models have focused on various fractionations of solar wind rather than condensation as the process for the evolution of noble gases in the terrestrial planets. However, these models cannot explain the observed gradient of the gases, nor do they account for the similar Ne/Ar ratios and the dissimilar planetary Ar/Kr ratios. More recent studies have focused on hydrodynamic escape to explain the fractionation of gases, like neon, in the atmosphere and the mantle. Escape theory also seems to explain, in part, the isotopically heavy argon on Mars, however, it does not explain the discrepancies observed for the abundances of argon and neon on Venus and the Earth. This has led to the assumption that some combination of solar wind implantation, absorption and escape are needed to explain the nature of planetary noble gases.

  8. Appraisal of transport and deformation in shale reservoirs using natural noble gas tracers

    Energy Technology Data Exchange (ETDEWEB)

    Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kuhlman, Kristopher L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robinson, David G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bauer, Stephen J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gardner, William Payton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Montana, Missoula, MT (United States)


    This report presents efforts to develop the use of in situ naturally-occurring noble gas tracers to evaluate transport mechanisms and deformation in shale hydrocarbon reservoirs. Noble gases are promising as shale reservoir diagnostic tools due to their sensitivity of transport to: shale pore structure; phase partitioning between groundwater, liquid, and gaseous hydrocarbons; and deformation from hydraulic fracturing. Approximately 1.5-year time-series of wellhead fluid samples were collected from two hydraulically-fractured wells. The noble gas compositions and isotopes suggest a strong signature of atmospheric contribution to the noble gases that mix with deep, old reservoir fluids. Complex mixing and transport of fracturing fluid and reservoir fluids occurs during production. Real-time laboratory measurements were performed on triaxially-deforming shale samples to link deformation behavior, transport, and gas tracer signatures. Finally, we present improved methods for production forecasts that borrow statistical strength from production data of nearby wells to reduce uncertainty in the forecasts.

  9. Perspectives of hyperpolarized noble gas MRI beyond 3He (United States)

    Lilburn, David M.L.; Pavlovskaya, Galina E.; Meersmann, Thomas


    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp 3He. A particular focus are the many intriguing experiments with 129Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp 83Kr MRI is discussed. PMID:23290627

  10. Trapping Mechanism of O2 in Water Ice as First Measured by Rosetta Spacecraft (United States)

    Laufer, Diana; Bar-Nun, Akiva; Greenberg, Adi Ninio


    One of the most surprising measurements of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument, ROSINA on the comet 67P/Churyumov-Gerasimenko was the detection of O2 along with N2 and noble gases which were measured for the first time in comets, along with the major constituents, water, CO and CO2. The O2 high abundance of

  11. A fiber optic sensor with a metal organic framework as a sensing material for trace levels of water in industrial gases. (United States)

    Ohira, Shin-Ichi; Miki, Yusuke; Matsuzaki, Toru; Nakamura, Nao; Sato, Yu-ki; Hirose, Yasuo; Toda, Kei


    Industrial gases such as nitrogen, oxygen, argon, and helium are easily contaminated with water during production, transfer and use, because there is a high volume fraction of water in the atmosphere (approximately 1.2% estimated with the average annual atmospheric temperature and relative humidity). Even trace water (quality problems in the process such as production of semiconductors. Therefore, it is important to monitor and to control trace water levels in industrial gases at each supplying step, and especially during their use. In the present study, a fiber optic gas sensor was investigated for monitoring trace water levels in industrial gases. The sensor consists of a film containing a metal organic framework (MOF). MOFs are made of metals coordinated to organic ligands, and have mesoscale pores that adsorb gas molecules. When the MOF, copper benzene-1,3,5-tricarboxylate (Cu-BTC), was used as a sensing material, we investigated the color of Cu-BTC with water adsorption changed both in depth and tone. Cu-BTC crystals appeared deep blue in dry gases, and then changed to light blue in wet gases. An optical gas sensor with the Cu-BTC film was developed using a light emitting diode as the light source and a photodiode as the light intensity detector. The sensor showed a reversible response to trace water, did not require heating to remove the adsorbed water molecules. The sample gas flow rate did not affect the sensitivity. The obtained limit of detection was 40 parts per billion by volume (ppbv). The response time for sample gas containing 2.5 ppmvH2O was 23 s. The standard deviation obtained for daily analysis of 1.0 ppmvH2O standard gas over 20 days was 9%. Furthermore, the type of industrial gas did not affect the sensitivity. These properties mean the sensor will be applicable to trace water detection in various industrial gases. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Noble gas isotopes in mineral springs and wells within the Cascadia forearc, Washington, Oregon, and California (United States)

    McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.


    IntroductionThis U.S. Geological Survey report presents laboratory analyses along with field notes for an exploratory study to document the relative abundance of noble gases in mineral springs and water wells within the Cascadia forearc of Washington, Oregon, and California (fig. 1). This report describes 14 samples collected in 2014 and 2015 and complements a previous report that describes 9 samples collected in 2012 and 2013 (McCrory and others, 2014b). Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath sample sites are derived from the McCrory and others (2012) slab model. Some of the springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none of the springs or wells currently has publicly available noble gas data. The helium and neon isotope values and ratios presented below are used to determine the sources and mixing history of these mineral and well waters (for example, McCrory and others, 2016).

  13. Effects of water-saving irrigation on emissions of greenhouse gases and prokaryotic communities in rice paddy soil. (United States)

    Ahn, Jae-Hyung; Choi, Min-Young; Kim, Byung-Yong; Lee, Jong-Sik; Song, Jaekyeong; Kim, Gun-Yeob; Weon, Hang-Yeon


    The effects of water-saving irrigation on emissions of greenhouse gases and soil prokaryotic communities were investigated in an experimental rice field. The water layer was kept at 1-2 cm in the water-saving (WS) irrigation treatment and at 6 cm in the continuous flooding (CF) irrigation treatment. WS irrigation decreased CH(4) emissions by 78 % and increased N(2)O emissions by 533 %, resulting in 78 % reduction of global warming potential compared to the CF irrigation. WS irrigation did not affect the abundance or phylogenetic distribution of bacterial/archaeal 16S rRNA genes and the abundance of bacterial/archaeal 16S rRNAs. The transcript abundance of CH(4) emission-related genes generally followed CH(4) emission patterns, but the difference in abundance between mcrA transcripts and amoA/pmoA transcripts best described the differences in CH(4) emissions between the two irrigation practices. WS irrigation increased the relative abundance of 16S rRNAs and functional gene transcripts associated with Anaeromyxobacter and Methylocystis spp., suggesting that their activities might be important in emissions of the greenhouse gases. The N(2)O emission patterns were not reflected in the abundance of N(2)O emission-related genes and transcripts. We showed that the alternative irrigation practice was effective for mitigating greenhouse gas emissions from rice fields and that it did not affect the overall size and structure of the soil prokaryotic community but did affect the activity of some groups.

  14. Chemistry of ice: Migration of ions and gases by directional freezing of water

    Directory of Open Access Journals (Sweden)

    Umer Shafique


    Full Text Available Redistribution of anions and cations creates an electrical imbalance in ice grown from electrolyte solutions. Movement of acidic and basic ions in cooling solutions can permanently change the pH of frozen and unfrozen parts of the system, largely. The extent of pH change associated with freezing is determined by solute concentration and the extent of cooling. In the present work, redistribution of hydrogen, hydroxyl, carbonate, and bicarbonate ions was studied during directional freezing in batch aqueous systems. Controlled freezing was employed vertically as well as radially in acidic and basic solutions. In each case, the ions substantially migrated along with moving freezing front. Conductometry and pH-metry were employed to monitor the moving ions. Besides, some other experiments were carried out with molecular gases, such as oxygen, carbon dioxide, and chlorine and an azeotropic mixture like water–ethanol. Findings can be used to understand possible changes that can occur in preserving materials by freezing.

  15. Experimental studies and model analysis of noble gas fractionation in low-permeability porous media (United States)

    Ding, Xin; Mack Kennedy, B.; Molins, Sergi; Kneafsey, Timothy; Evans, William C.


    Gas flow through the vadose zone from sources at depth involves fractionation effects that can obscure the nature of transport and even the identity of the source. Transport processes are particularly complex in low permeability media but as shown in this study, can be elucidated by measuring the atmospheric noble gases. A series of laboratory column experiments was conducted to evaluate the movement of noble gas from the atmosphere into soil in the presence of a net efflux of CO2, a process that leads to fractionation of the noble gases from their atmospheric abundance ratios. The column packings were designed to simulate natural sedimentary deposition by interlayering low permeability ceramic plates and high permeability beach sand. Gas samples were collected at different depths at CO2 fluxes high enough to cause extreme fractionation of the noble gases (4He/36Ar > 20 times the air ratio). The experimental noble gas fractionation-depth profiles were in good agreement with those predicted by the dusty gas (DG) model, demonstrating the applicability of the DG model across a broad spectrum of environmental conditions. A governing equation based on the dusty gas model was developed to specifically describe noble gas fractionation at each depth that is controlled by the binary diffusion coefficient, Knudsen diffusion coefficient and the ratio of total advection flux to total flux. Finally, the governing equation was used to derive the noble gas fractionation pattern and illustrate how it is influenced by soil CO2 flux, sedimentary sequence, thickness of each sedimentary layer and each layer's physical parameters. Three potential applications of noble gas fractionation are provided: evaluating soil attributes in the path of gas flow from a source at depth to the atmosphere, testing leakage through low permeability barriers used to isolate buried waste, and tracking biological methanogenesis and methane oxidation associated with hydrocarbon degradation.

  16. Fullerenes, Graphitic Smokes and the Nature of Planetary Gases (United States)

    Becker, L.; Poreda, R.; Nuth, J.


    We have begun to carry out experiments on synthetic material "graphitic smokes" to evaluate the noble gases in the larger fullerene cages. Graphitic smokes (GS) are produced by electrically heating a hollowed out graphite rod in a noble gas atmosphere. The hollow graphite rod allows the C to condense out of the gas more uniformly in comparison to the Kratschmer arc evaporator synthesis of fullerenes. Some of these carbonaceous condensates were analyzed for Xe and values as high as 13.7 × 10-6 cm^3 STP/bm of 132Xe were obtained. This is some 2X magnitude greater than typical 132Xe amounts for other synthesized carbonaceous residues. We obtained some graphitic smokes synthesized in a noble gas mixture (49% neon, 49% argon, 1% Xe and 1% Kr with the balance of pressure coming from He) and used our fullerene extraction protocol to determine whether fullerene was a carrier phase for the noble gases measured in the graphitic smoke material. Preliminary measurements of He and Ne in toluene extracted graphitic smokes residues (100 μg) indicated that fullerene (mostly C60 and C70) is indeed a carrier phase. Our yield for He corresponds to one ^4He per 880,000 fullerene molecules and is similar to the abundances measured in synthetic fullerenes produced in the arc evaporator. We are continuing our studies of the graphitic smokes with emphasis on the isolation and separation of the larger cages (C84-C200) and direct measurements of the noble gases. The graphitic smokes will be prepared with various mixtures of noble gases of known composition and extracted for fullerenes. The very efficient trapping of Xe in the graphitic smokes strongly suggests a more significant role for the larger fullerene cages to encapsulate the heavy noble gases. A more complete characterization of the larger fullerene cages may well lead to a better understanding of the nature of planetary atmospheres.

  17. Application of advanced oxidation processes for cleaning of industrial water generated in wet dedusting of shaft furnace gases. (United States)

    Czaplicka, Marianna; Kurowski, Ryszard; Jaworek, Katarzyna; Bratek, Łukasz


    The paper presents results of studies into advanced oxidation processes in 03 and 03/UV systems. An advanced oxidation process (AOP) was conducted to reduce the load of impurities in circulating waters from wet de-dusting of shaft furnace gases. Besides inorganic impurities, i.e. mainly arsenic compounds (16 g As L(-1) on average), lead, zinc, chlorides and sulphates, the waters also contain some organic material. The organic material is composed of a complex mixture that contains, amongst others, aliphatic compounds, phenol and its derivatives, pyridine bases, including pyridine, and its derivatives. The test results show degradation of organic and inorganic compounds during ozonation and photo-oxidation processes. Analysis of the solutions from the processes demonstrated that the complex organic material in the industrial water was oxidized in ozonation and in photo-oxidation, which resulted in formation of aldehydes and carboxylic acids. Kinetic degradation of selected pollutants is presented. Obtained results indicated that the O3/UV process is more effective in degradation of organic matter than ozonation. Depending on the process type, precipitation of the solid phase was observed. The efficiency of solid-phase formation was higher in photo-oxidation with ozone. It was found that the precipitated solid phase is composed mainly of arsenic, iron and oxygen.

  18. Noble gases in diamonds - Occurrences of solarlike helium and neon (United States)

    Honda, M.; Reynolds, J. H.; Roedder, E.; Epstein, S.


    Seventeen diamond samples from diverse locations were analyzed for the contents of He, Ar, Kr, and Xe, and of their isotopes, using a Reynolds (1956) type glass mass spectrometer. The results disclosed a large spread in the He-3/He-4 ratios, ranging from values below atmospheric to close to the solar ratio. In particular, solarlike He-3/He-4 ratios were seen for an Australian colorless diamond composite and an Arkansas diamond, which also displayed solarlike neon isotopic ratios. Wide variation was also observed in the He-4/Ar-40 ratios, suggesting a complex history for the source regions and the diamond crystallization processes.

  19. The Chemistry of the Noble Gases, Understanding the Atom Series. (United States)

    Chernick, Cedric L.

    The history of the discovery, isolation, characterization, production and use of argon, krypton, xenon, helium, and radon is followed by an account of early attempts to react them with other elements. The use of the electron shell theory of valence to explain their inertness and the reactions of chemists to the production of xenon compounds is…

  20. Chalcogenide Aerogels as Sorbents for Noble Gases (Xe, Kr). (United States)

    Subrahmanyam, Kota S; Spanopoulos, Ioannis; Chun, Jaehun; Riley, Brian J; Thallapally, Praveen K; Trikalitis, Pantelis N; Kanatzidis, Mercouri G


    High-surface-area molybdenum sulfide (MoSx) and antimony sulfide (SbSx) chalcogels were studied for Xe/Kr gas separation. The intrinsic soft Lewis basic character of the chalcogel framework is a unique property among the large family of porous materials and lends itself to a potential new approach toward the selective separation of Xe over Kr. Among these chalcogels, MoSx shows the highest Xe and Kr uptake, reaching 0.69 mmol g(-1) (1.05 mmol cm(-3)) and 0.28 mmol g(-1) (0.42 mmol cm(-3)) respectively, at 273 K and 1 bar. The corresponding isosteric heat of adsorption at zero coverage (Qst(0)) is 22.8 and 18.6 kJ mol(-1) and both are the highest among the selected chalcogels. The IAST (10:90) Xe/Kr selectivity at 273 K for MoSx is 6.0, whereas for SbSx chalcogels, it varies in the range 2.0-2.8. The higher formal charge of molybdenum, Mo(4+), in MoSx versus that of antimony, Sb(3+), in SbSx coupled with its larger atomic size could induce higher polarizability in the MoSx framework and therefore higher Xe/Kr selectivity.

  1. Effect of noble gases on an atmospheric greenhouse /Titan/. (United States)

    Cess, R.; Owen, T.


    Several models for the atmosphere of Titan have been investigated, taking into account various combinations of neon and argon. The investigation shows that the addition of large amounts of Ne and/or Ar will substantially reduce the hydrogen abundance required for a given greenhouse effect. The fact that a large amount of neon should be present if the atmosphere is a relic of the solar nebula is an especially attractive feature of the models, because it is hard to justify appropriate abundances of other enhancing agents.

  2. Momentum transfer cross sections for the heavy noble gases (United States)

    Stauffer, A. D.; McEachran, R. P.


    We have used our relativistic optical potential method [1] to calculate the momentum transfer cross sections for Ar, Kr and Xe from threshold to 1000 eV. The target ground state as well as the open excited and ionization channels used in the optical potential have been calculated using the MCDF program [2]. We have included 17 excitation channels for Ar, 26 for Kr and 15 for Xe. In the ionization channels, ionization of the outer p, s and d shells were included for Kr and Xe while for Ar all electrons were allowed to be ionized. Comparisons with previous calculations and experimental measurements will be included. We also include analytic fits to our cross sections to aid in plasma modelling studies. [4pt] [1] S. Chen, R. P. McEachran and A. D. Stauffer, J. Phys. B 41 025201 (2008) [0pt] [2] I. P. Grant, B. J. McKenzie, P. H. Norrington, D. F. Mayers and N. C. Pyper, Comput. Phys. Commun. 21 207 (1980)

  3. Method for recycling radioactive noble gases for functional pulmonary imaging

    Energy Technology Data Exchange (ETDEWEB)

    Forouzan-Rad, M.


    A theoretical treatment of the dynamic adsorption and desorption processes in the adsorption column is developed. The results of this analysis are compared with the space-time measurements of /sup 133/Xe activity distribution in a charcoal column, when trace amounts of this gas in exponentially decreasing concentrations are fed into the column. Based on these investigations, a recycling apparatus is designed for use with xenon isotopes, especially /sup 127/Xe, in studies of pulmonary function. The apparatus takes advantage of the high adsorbability of activated coconut charcoal for xenon a low temperature (-78/sup 0/C) in order to trap the radioactive xenon gas that is exhaled during each ventilation-perfusion study. The trapped xenon is then recovered by passing low-pressure steam through the charcoal column. It is found that steam removes xenon from the surface of the charcoal more effectively than does heating and evacuation of the charcoal bed. As a result, an average xenon recovery of 96 percent has been achieved. Improved design parameters are discussed. (auth)

  4. Chalcogenide Aerogels as Sorbents for Noble Gases (Xe, Kr)

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, Kota S. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Spanopoulos, Ioannis [Department; Chun, Jaehun [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Riley, Brian J. [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Thallapally, Praveen K. [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Trikalitis, Pantelis N. [Department; Kanatzidis, Mercouri G. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States


    High surface MoSx and SbSx chalcogels were studied for Xe/Kr gas separation. The intrinsic soft character of the chalcogel framework is a unique property among the large family of porous materials and offers a potential new approach towards the selective separation of Xe over Kr. Among these chalcogels, MoSx shows the highest Xe and Kr uptake, reaching 0.69 mmol g-1 (1.05 mmol cm-3) and 0.28 mmol g-1 (0.42 mmol cm-3) respectively, at 273 K and 1 bar. The corresponding isosteric heat of adsorption at zero coverage (Qst0) is 22.8 and 18.6 kJ mol-1 and both are the highest among the selected chalcogels. The IAST (10:90) Xe/Kr selectivity at 273 K for MoSx is 6.0 while for SbSx chalcogels varies in the range 2.0-2.8. The higher formal charge of molybdenum, Mo4+, in MoSx versus that of antimony, Sb3+, in SbSx coupled with its larger atomic size could induce higher polarizability in the MoSx framework and therefore higher Xe/Kr selectivity.

  5. Assessment of Noble Gases in the Savannah River Site Environment

    Energy Technology Data Exchange (ETDEWEB)

    Carlton, W.H.; Murphy, C.E. Jr.


    A series of documents has been published that assesses the impact of various radionuclides released to the environment by Savannah River Site operations. The quantity released, the disposition of the radionuclides in the environment, and the dose to offsite individuals has been presented for carbon, cesium, iodine, plutonium, strontium, technetium, tritium, and uranium. An assessment of the impact of non-radioactive mercury also has been published.

  6. Surface tension of water and acid gases from Monte Carlo simulations (United States)

    Ghoufi, A.; Goujon, F.; Lachet, V.; Malfreyt, P.


    We report direct Monte Carlo (MC) simulations on the liquid-vapor interfaces of pure water, carbon dioxide, and hydrogen sulfide. In the case of water, the recent TIP4P/2005 potential model used with the MC method is shown to reproduce the experimental surface tension and to accurately describe the coexistence curves. The agreement with experiments is also excellent for CO2 and H2S with standard nonpolarizable models. The surface tensions are calculated by using the mechanical and the thermodynamic definitions via profiles along the direction normal to the surface. We also discuss the different contributions to the surface tension due to the repulsion-dispersion and electrostatic interactions. The different profiles of these contributions are proposed in the case of water.

  7. Modeling the infrastructure dynamics of China -- Water, agriculture, energy, and greenhouse gases

    Energy Technology Data Exchange (ETDEWEB)

    Conrad, S.H.; Drennen, T.E.; Engi, D.; Harris, D.L.; Jeppesen, D.M.; Thomas, R.P.


    A comprehensive critical infrastructure analysis of the People`s Republic of China was performed to address questions about China`s ability to meet its long-term grain requirements and energy needs and to estimate greenhouse gas emissions in China likely to result from increased agricultural production and energy use. Four dynamic computer simulation models of China`s infrastructures--water, agriculture, energy and greenhouse gas--were developed to simulate, respectively, the hydrologic budgetary processes, grain production and consumption, energy demand, and greenhouse gas emissions in China through 2025. The four models were integrated into a state-of-the-art comprehensive critical infrastructure model for all of China. This integrated model simulates diverse flows of commodities, such as water and greenhouse gas, between the separate models to capture the overall dynamics of the integrated system. The model was used to generate projections of China`s available water resources and expected water use for 10 river drainage regions representing 100% of China`s mean annual runoff and comprising 37 major river basins. These projections were used to develop estimates of the water surpluses and/or deficits in the three end-use sectors--urban, industrial, and agricultural--through the year 2025. Projections of the all-China demand for the three major grains (corn, wheat, and rice), meat, and other (other grains and fruits and vegetables) were also generated. Each geographic region`s share of the all-China grain demand (allocated on the basis of each region`s share of historic grain production) was calculated in order to assess the land and water resources in each region required to meet that demand. Growth in energy use in six historically significant sectors and growth in greenhouse gas loading were projected for all of China.


    NARCIS (Netherlands)


    A surface-aerated stirred cell with a flat liquid surface was used to investigate the absorption of propane and ethene gas into slurries of activated carbon and water. Slurries with a solids concentration up to 4% by weight and particle diameters up to 565-mu-m were used. The experimental mass

  9. A capacitance sensor for water: trace moisture measurement in gases and organic solvents. (United States)

    Ohira, Shin-Ichi; Goto, Kayoko; Toda, Kei; Dasgupta, Purnendu K


    The determination of water in various matrices is one of the most important analytical measurements. We report on a high-resolution capacitance-based moisture sensor utilizing a thin film of a perfluorosulfonate ionomer (PFSI)-H(3)PO(4) composite in a flow-through configuration, for both gas and liquid samples. Incorporation of H(3)PO(4) into a PFSI sensing film improved the limit of detection (LOD) (signal-to-noise ratio, S/N = 3) by a factor of 16 in the gas phase to 0.075% relative humidity (RH) (dew point = -56 °C). The response time was dependent on the sensing film thickness and composition and was as low as ∼60 ms. The temperature dependence of the sensor response, and its relative selectivity over alcohol and various other solvents, are reported. Measurement of water in organic solvents was carried out in two different ways. In one procedure, the sample was vaporized and swept into the detector (e.g., in a gas chromatograph (GC) without a column); it permitted a throughput of 80 samples/h. This is well-suited for higher (%) levels of water. In the other method, a flow injection analysis system integrated to a tubular dialysis membrane pervaporizer (PV-FIA) was used; the LOD for water in ethanol was 0.019% (w/w). We demonstrated the temporal course of drying of ethanol by Drierite; the PV-FIA results showed excellent correspondence (r(2) > 0.99) with results from GC-thermal conductivity detection. The system can measure trace water in many types of organic solvents; no reagent consumption is involved.

  10. Signal-to-noise ratio comparison of encoding methods for hyperpolarized noble gas MRI (United States)

    Zhao, L.; Venkatesh, A. K.; Albert, M. S.; Panych, L. P.


    Some non-Fourier encoding methods such as wavelet and direct encoding use spatially localized bases. The spatial localization feature of these methods enables optimized encoding for improved spatial and temporal resolution during dynamically adaptive MR imaging. These spatially localized bases, however, have inherently reduced image signal-to-noise ratio compared with Fourier or Hadamad encoding for proton imaging. Hyperpolarized noble gases, on the other hand, have quite different MR properties compared to proton, primarily the nonrenewability of the signal. It could be expected, therefore, that the characteristics of image SNR with respect to encoding method will also be very different from hyperpolarized noble gas MRI compared to proton MRI. In this article, hyperpolarized noble gas image SNRs of different encoding methods are compared theoretically using a matrix description of the encoding process. It is shown that image SNR for hyperpolarized noble gas imaging is maximized for any orthonormal encoding method. Methods are then proposed for designing RF pulses to achieve normalized encoding profiles using Fourier, Hadamard, wavelet, and direct encoding methods for hyperpolarized noble gases. Theoretical results are confirmed with hyperpolarized noble gas MRI experiments. Copyright 2001 Academic Press.

  11. First ECR-Ionized Noble Gas Radioisotopes at ISOLDE

    CERN Document Server

    Wenander, F; Gaubert, G; Jardin, P; Lettry, Jacques


    The production of light noble gas radioisotopes with high ionization potentials has been hampered by modest ionization efficiencies for standard plasma ion-sources. However, the decay losses are minimal as the lingering time of light noble gases within plasma ion-sources is negligible when compared to its diffusion out of the target material. Previous singly charged ECRIS have shown a higher efficiency but also a lingering time of the order of 1 s and a total weight that prevents remote handling by the ISOLDE robot. The compact MINIMONO efficiently addressed the lingering time and weight issues. In addition, the MINIMONO maintained the high off-line ionization efficiency for light noble gases. This paper describes a standard ISOLDE target unit equipped with a MINIMONO ion-source and the first tests. The ion-source has been tested off-line and equipped with a CaO target for on-line tests. Valuable information was gained about high current (100-500 muA) transport through the ISOLDE mass separators designed for ...

  12. Synthesis of Zeolite Materials for Noble Gas Separation

    Energy Technology Data Exchange (ETDEWEB)

    Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rivera, O. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Wellons, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    Microporous zeolite adsorbent materials are widely used as a medium for separating gases. Adsorbent gas separation systems can run at ambient temperature and require minimal pressure to flow the input gas stream across the adsorbent bed. This allows for low energy consumption relative to other types of separation systems. Specific zeolites also have a high capacity and selectivity for the gases of interest, leading to compact and efficient separation systems. These characteristics are particularly advantageous for the application of signatures detection for non-proliferation, which often requires portable systems with low power draw. Savannah River National Laboratory currently is the leader in using zeolites for noble gas sampling for non-proliferation detection platforms. However, there is a constant customer need for improved sampling capabilities. Development of improved zeolite materials will lead to improved sampling technology. Microwave-assisted and conventional hydrothermal synthesis have been used to make a variety of zeolites tailored for noble gas separation. Materials characterization data collected in this project has been used to help guide the synthesis of improved zeolite materials. Candidate materials have been down-selected based on highest available surface area, maximum overall capacity for gas adsorption and highest selectivity. The creation of improved adsorbent materials initiated in this project will lead to development of more compact, efficient and effective noble gas collectors and concentrators. The work performed in this project will be used as a foundation for funding proposals for further material development as well as possible industrial applications.

  13. [Diurnal changes in greenhouse gases at water-air interface of Xiangxi River in autumn and their influencing factors]. (United States)

    Huang, Wen-Min; Zhu, Kong-Xian; Zhao, Wei; Yu, Bo-Shi; Yuan, Xi-Gong; Feng, Rui-Jie; Bi, Yong-Hong; Hu, Zheng-Yu


    With the closed chamber and gas chromatography method, a 24-hour continuous monitoring was carried out to understand the greenhouse gases fluxes across the water-air interface of the Xiangxi River Bay, the Three-Gorges Reservoir in Autumn. Results indicated that the fluxes of CO2, CH4 and N2O across the water-air interface showed an obvious diurnal variation. The absorption and emission process of CH4 showed strong diurnal variation during the experimental period, reaching the highest emission at 1 am, whereas CO2 and N2O were emitted all day. The fluxes of CO2 ranged from 20.1-97.5 mg x (m2 x h)(-1) at day and 32.7-42.5 mg x (m2 x h)(-1) at night, the fluxes of N2O ranged from 18.4-133.7 microg x (m2 x h)(-1) at day and 42.1-102.6 microg x (m2 x h)(-1) at night. The fluxes of CO2 had positive correlation with wind speed and negative correlation with pH. The fluxes of N2O had positive correlation with pH.

  14. Targets Involved in Cardioprotection by the Non-Anesthetic Noble Gas Helium. (United States)

    Weber, Nina C; Smit, Kirsten F; Hollmann, Markus W; Preckel, Benedikt


    Research data from the past decade indicate that noble gases like xenon and helium exert profound cardioprotection when applied before, during or after organ ischemia. Of all noble gases, especially helium, has gained interest in the past years because it does not have an anesthetic "side effect" like xenon, allowing application of this specific gas in numerous clinical ischemia/reperfusion situations. Because helium has several unique characteristics and no hemodynamic side effects, helium could be administered in severely ill patients. Investigations in animals as well as in humans have proven that this noble gas is not completely inert and can induce several biological effects. Though the underlying molecular mechanisms of helium-induced cardiac protection are still not yet fully understood, recently different signaling pathways have been elucidated.

  15. Effects of 17β-estradiol on emissions of greenhouse gases in simulative natural water body. (United States)

    Ruan, Aidong; Zhao, Ying; Liu, Chenxiao; Zong, Fengjiao; Yu, Zhongbo


    Environmental estrogens are widely spread across the world and are increasingly thought of as serious contaminators. The present study looks at the influence of different concentrations of 17β-estradiol on greenhouse gas emissions (CO2 , CH4 , and N2 O) in simulated systems to explore the relationship between environmental estrogen-pollution and greenhouse gas emissions in natural water bodies. The present study finds that 17β-estradiol pollution in simulated systems has significant promoting effects on the emissions of CH4 and CO2 , although no significant effects on N2 O emissions. The present study indicates that 17β-estradiol has different effects on the different elements cycles; the mechanism of microbial ecology is under review. © 2015 SETAC.

  16. Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow

    DEFF Research Database (Denmark)

    Massman, W.J.; Ibrom, Andreas


    the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent...... diffusivity and tube airstream velocity). We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption....../desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity...

  17. Effect of dissolved gases in water on acoustic cavitation and bubble growth rate in 0.83 MHz megasonic of interest to wafer cleaning. (United States)

    Kang, Bong-Kyun; Kim, Min-Su; Park, Jin-Goo


    Changes in the cavitation intensity of gases dissolved in water, including H2, N2, and Ar, have been established in studies of acoustic bubble growth rates under ultrasonic fields. Variations in the acoustic properties of dissolved gases in water affect the cavitation intensity at a high frequency (0.83 MHz) due to changes in the rectified diffusion and bubble coalescence rate. It has been proposed that acoustic bubble growth rates rapidly increase when water contains a gas, such as hydrogen faster single bubble growth due to rectified diffusion, and a higher rate of coalescence under Bjerknes forces. The change of acoustic bubble growth rate in rectified diffusion has an effect on the damping constant and diffusivity of gas at the acoustic bubble and liquid interface. It has been suggested that the coalescence reaction of bubbles under Bjerknes forces is a reaction determined by the compressibility and density of dissolved gas in water associated with sound velocity and density in acoustic bubbles. High acoustic bubble growth rates also contribute to enhanced cavitation effects in terms of dissolved gas in water. On the other hand, when Ar gas dissolves into water under ultrasound field, cavitation behavior was reduced remarkably due to its lower acoustic bubble growth rate. It is shown that change of cavitation intensity in various dissolved gases were verified through cleaning experiments in the single type of cleaning tool such as particle removal and pattern damage based on numerically calculated acoustic bubble growth rates. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Solvation theory to provide a molecular interpretation of the hydrophobic entropy loss of noble-gas hydration. (United States)

    Irudayam, Sheeba Jem; Henchman, Richard H


    An equation for the chemical potential of a dilute aqueous solution of noble gases is derived in terms of energies, force and torque magnitudes, and solute and water coordination numbers, quantities which are all measured from an equilibrium molecular dynamics simulation. Also derived are equations for the Gibbs free energy, enthalpy and entropy of hydration for the Henry's law process, the Ostwald process, and a third proposed process going from an arbitrary concentration in the gas phase to the equivalent mole fraction in aqueous solution which has simpler expressions for the enthalpy and entropy changes. Good agreement with experimental hydration free energies is obtained in the TIP4P and SPC/E water models although the solute's force field appears to affect the enthalpies and entropies obtained. In contrast to other methods, the approach gives a complete breakdown of the entropy for every degree of freedom and makes possible a direct structural interpretation of the well-known entropy loss accompanying the hydrophobic hydration of small non-polar molecules under ambient conditions. The noble-gas solutes experience only a small reduction in their vibrational entropy, with larger solutes experiencing a greater loss. The vibrational and librational entropy components of water actually increase but only marginally, negating any idea of water confinement. The term that contributes the most to the hydrophobic entropy loss is found to be water's orientational term which quantifies the number of orientational minima per water molecule and how many ways the whole hydrogen-bond network can form. These findings help resolve contradictory deductions from experiments that water structure around non-polar solutes is similar to bulk water in some ways but different in others. That the entropy loss lies in water's rotational entropy contrasts with other claims that it largely lies in water's translational entropy, but this apparent discrepancy arises because of different

  19. Position resolution limits in pure noble gaseous detectors for X-ray energies from 1 to 60 keV

    Directory of Open Access Journals (Sweden)

    C.D.R. Azevedo


    Full Text Available The calculated position resolutions for X-ray photons (1–60 keV in pure noble gases at atmospheric pressure are presented. In this work we show the influence of the atomic shells and the detector dimensions on the intrinsic position resolution of the used noble gas. The calculated results were obtained by using a new software tool, Degrad, and compared to the available experimental data.

  20. Aespoe Hard Rock Laboratory. Prototype Repository. Analyses of microorganisms, gases and water chemistry in buffer and backfill, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Lydmark, Sara (Microbial Analytics Sweden AB (Sweden))


    The Prototype repository is an international project to build and study a full-scale model of the planned Swedish final repository for spent nuclear fuel. The Prototype repository differs from a real storage in that it is drained. For example, this makes the swelling pressure lower in the Prototype repository compared with a real storage. The project is being conducted at the Aespoe Hard Rock Laboratory (HRL) in crystalline rock at a depth of approximately 450 m. A monitoring programme is investigating the evolution of the water chemistry, gas, and microbial activity at the site, and one of the specific aims is to monitor the microbial consumption of oxygen in situ in the Prototype repository. This document describes the results of the analyses of microbes, gases, and chemistry inside and outside the Prototype in 2009. Hydrogen, helium, nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethane, and ethene were analysed in the following sampling points in the Prototype repository: KBU10001, KBU10002, KBU10004, KBU10006, KBU10008, KFA01 and KFA04. Where the sampling points in the Prototype delivered pore water, the water was analysed for amount of ATP (i.e., the biovolume), cultivable heterotrophic aerobic bacteria (CHAB), sulphate-reducing bacteria (SRB), methane-oxidizing bacteria (MOB), autotrophic acetogens (AA) and in some cases iron-reducing bacteria (IRB). Cultivation methods were also compared with qPCR molecular techniques to evaluate these before next year's decommission of the Prototype repository. The collected pore water from the Prototype repository was subject to chemistry analysis (as many analyses were conducted as the amount of water allowed). In addition, groundwater from two borehole sections in the rock surrounding the Prototype was analysed regarding its gas composition, microbiology and redox. Chemistry data from a previous investigation of the groundwater outside the Prototype repository were compared with the pore water

  1. Hole dynamics in noble metals


    Campillo, I.; Rubio, A.; Pitarke, J. M.; Goldmann, A.; Echenique, P. M.


    We present a detailed analysis of hole dynamics in noble metals (Cu and Au), by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d-holes in noble metals exhibit longer inelastic lifetimes than excited sp-electrons, in agreement with experiment. The density of states available for d-hole decay is larger than that for the decay of excited electrons; however, th...

  2. Irritant gases

    NARCIS (Netherlands)

    Meulenbelt, J

    Acute inhalation injury can result from the use of household cleaning agents (e.g. chlorine, ammonia), industrial or combustion gases (e.g. sulfur dioxide, nitrogen oxides) or bioterrorism. The severity of the injury is to a great extent determined by the circumstances of exposure. If exposure was

  3. Isotopic mass-dependence of noble gas diffusion coefficients inwater

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.


    Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D prop m-beta with beta<0.2, whichrefutes the kinetic theory model underlying all currentapplications.

  4. Development of detection techniques for the Swedish noble gas sampler

    Energy Technology Data Exchange (ETDEWEB)

    Ringbom, A


    A short review on the radioactive properties of noble gas isotopes relevant for monitoring of nuclear activities is given, together with a brief discussion of the existing systems for detection of radioactive noble gases. A 4{pi} detection system to be used in the automatic version of the Swedish noble gas sampling device is described. Monte Carlo calculations of the total gamma and beta efficiency for different detector designs have been performed, together with estimates of the resulting minimum detectable concentration (MDC). The estimated MDC values for detection of the {sup 133g}Xe 81 keV and the {sup 135g}Xe 250 keV gamma lines are around 0.3 mBq/m{sup 3} in both cases. This is a factor of three lower than the detection limit required for a sampling station in the Comprehensive Nuclear-Test-Ban Treaty monitoring network. The possibility to modify the system to detect {sup 85}Kr is also discussed 27 refs, 13 figs, 3 tabs

  5. Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

    Energy Technology Data Exchange (ETDEWEB)

    Sargent, B. A. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); D' Alessio, P.; Calvet, N. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building, Ann Arbor, MI 48109 (United States); Furlan, E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Green, J. [Department of Astronomy, University of Texas, 1 University Station, Austin, TX 78712 (United States); Pontoppidan, K., E-mail: [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)


    We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

  6. Aespoe Hard Rock Laboratory. Prototype repository. Analyses of microorganisms, gases, and water chemistry in buffer and backfill, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Lydmark, Sara [Microbial Analytics Sweden AB, Moelnlycke (Sweden)


    The prototype repository (hereafter, 'Prototype') is an international project to build and study a fullscale model of the planned Swedish final repository for spent nuclear fuel. However, the Prototype differs from a real storage in that it is drained, which makes the swelling pressure lower in the Prototype than in a real storage facility. The heat from the radioactive decay is simulated by electrical heaters. The project is being conducted at the Aespoe Hard Rock Laboratory (HRL) in crystalline rock at a depth of approximately 450 m. A monitoring programme is investigating the evolution of the water chemistry, gas, and microbial activity at the site, and a specific aim is to monitor the microbial consumption of oxygen in situ in the Prototype. This document describes the results of the analyses of microbes, gases, and chemistry inside the Prototype in 2010. Hydrogen, helium, nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethane, and ethene were analysed at the following sampling points in the Prototype: KBU10001, KBU10002, KBU10004, KBU10008, and KFA04. Where the sampling points in the Prototype delivered pore water, the water was analysed for amount of ATP (i.e. the biovolume), culturable heterotrophic aerobic bacteria (CHAB), sulphate-reducing bacteria (SRB), methane-oxidizing bacteria (MOB), and iron-reducing bacteria (IRB). The pore water collected from the Prototype was subject to as many chemical analyses as the amount of water allowed. Chemical analyses were also performed on pore water from two additional sampling points, KBU10005 and KBU10006. Chemical data from a previous investigation of the groundwater outside the Prototype were compared with the pore water chemistry. The improved sampling and analysis protocols introduced in 2007 worked very well. The International Progress Report (IPR) 08-01 (Eriksson 2008) revealed that many of the hydrochemical sampling points differ greatly from each other. The 16 sampling points were

  7. Noble Gas Concept Of Operation

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    The intent of this document is to provide the reader with an understanding of a general approach to performing the noble gas component of an On Site Inspection or OSI. The authors of this document recognize that owing to the wide range of scenarios that are possible for carrying out an underground nuclear explosion, the diverse sets of information that might be available to the inspection team initially and the potential range of political and physical constraints imposed during the inspection, a satisfactory prescriptive approach to carrying out the noble gas component of an OSI is unlikely. Rather, the authors intend only to aid the reader in understanding what a reasonable course of actions or responses may be as performed by an inspection team (IT) during a general OSI. If this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from this general scenario, it will have achieved its intent.

  8. Noble-Metal Chalcogenide Nanotubes

    Directory of Open Access Journals (Sweden)

    Nourdine Zibouche


    Full Text Available We explore the stability and the electronic properties of hypothetical noble-metal chalcogenide nanotubes PtS2, PtSe2, PdS2 and PdSe2 by means of density functional theory calculations. Our findings show that the strain energy decreases inverse quadratically with the tube diameter, as is typical for other nanotubes. Moreover, the strain energy is independent of the tube chirality and converges towards the same value for large diameters. The band-structure calculations show that all noble-metal chalcogenide nanotubes are indirect band gap semiconductors. The corresponding band gaps increase with the nanotube diameter rapidly approaching the respective pristine 2D monolayer limit.

  9. A test of Pierotti's theory for the solubility of gases in liquids, by means of literature data of solubility and entropy of solution

    NARCIS (Netherlands)

    Ligny, C.L. de; Veen, N.G. van der

    Pierotti's theory for the solubility of gases in liquids is tested by means of a large amount of literature data on solubility and entropy of solution. The involved solutes comprise the noble gases, mercury vapour, inorganic gases and hydrocarbons up to propane. The involved solvents comprise

  10. Noble gas isotope measurements for spent nuclear fuel reprocessing. IAEA Task 90/0A211 interim report

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, G.B.


    The nuclear fission of actinides in reactor fuel produces large quantities of Kr and Xe as fission products. Because of the high levels of fission Kr and Xe, sample collection and analysis of noble gases for spent fuel diagnostic measurements is a simple, straight-forward technique. In modern reprocessing plants with continuous dissolvers, it will not be possible to use traditional methods for isolating input batches of fuel. This study investigates the feasibility of using noble gas isotope abundance measurements (isotope correlation techniques - ICT) to solve safeguards requirements. Noble gas measurements might be able to provide an independent analysis of Pu contained within dissolves fuel, on an individual fuel assembly basis. The isotopic composition of Kr and Xe in spent fuel reflects both the composition (isotope abundance ratios) of the fission products and the effects of neutron capture on those fission products. We have reviewed the available literature for noble gas analyses of spent reactor fuel. While references are made to noble gas isotope correlations over the last 20 years, we have found little if any detailed analysis of large data sets. The literature search did find several useful reports. Of these papers, one is particularly useful for evaluating noble gas isotopic compositions. The ``Benchmark-paper`` (1) contains 54 Kr and 56 Xe isotopic composition analyses for 4 different reactors with a variety of fuel enrichment factors. Burnup ranges from 8000 to 37000 MWd/tU. Besides the noble gas measurements, a variety of other measurements are reported (actinides and fission products).

  11. Tracing Noble Gas Radionuclides in the Environment

    CERN Document Server

    Collon, P; Lu, Z T


    Trace analysis of radionuclides is an essential and versatile tool in modern science and technology. Due to their ideal geophysical and geochemical properties, long-lived noble gas radionuclides, in particular, 39Ar (t1/2 = 269 yr), 81Kr (t1/2 = 2.3x10^5 yr) and 85Kr (t1/2 = 10.8 yr), have long been recognized to have a wide range of important applications in Earth sciences. In recent years, significant progress has been made in the development of practical analytical methods, and has led to applications of these isotopes in the hydrosphere (tracing the flow of groundwater and ocean water). In this article, we introduce the applications of these isotopes and review three leading analytical methods: Low-Level Counting (LLC), Accelerator Mass Spectrometry (AMS) and Atom Trap Trace Analysis (ATTA).

  12. Noble Gas Inventory of Micrometeorites Collected at the Transantarctic Mountains (TAM) and Indications for Their Provenance (United States)

    Ott, U.; Baecker, B.; Folco, L.; Cordier, C.


    A variety of processes have been considered possibly contributing the volatiles including noble gases to the atmospheres of the terrestrial planets (e.g., [1-3]). Special consideration has been given to the concept of accretion of volatile-rich materials by the forming planets. This might include infalling planetesimals and dust, and could include material from the outer asteroid belt, as well as cometary material from the outer solar system. Currently, the dominant source of extraterrestrial material accreted by the Earth is represented by micrometeorites (MMs) with sizes mostly in the 100-300 micron range [3, 4]). Their role has been assessed by [3], who conclude that accretion of early micrometeorites played a major role in the formation of the terrestrial atmosphere and oceans. We have therefore set out to investigate in more detail the inventory of noble gases in MMs. Here we summarize some of our results obtained on MMs collected in micrometeorite traps of the Transantarctic Mountains [5].

  13. New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth (United States)

    Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan


    We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic

  14. Stable isotope and noble gas constraints on the source and residence time of spring water from the Table Mountain Group Aquifer, Paarl, South Africa and implications for large scale abstraction (United States)

    Miller, J. A.; Dunford, A. J.; Swana, K. A.; Palcsu, L.; Butler, M.; Clarke, C. E.


    Large scale groundwater abstraction is increasingly being used to support large urban centres especially in areas of low rainfall but presents particular challenges in the management and sustainability of the groundwater system. The Table Mountain Group (TMG) Aquifer is one of the largest and most important aquifer systems in South Africa and is currently being considered as an alternative source of potable water for the City of Cape Town, a metropolis of over four million people. The TMG aquifer is a fractured rock aquifer hosted primarily in super mature sandstones, quartzites and quartz arenites. The groundwater naturally emanates from numerous springs throughout the cape region. One set of springs were examined to assess the source and residence time of the spring water. Oxygen and hydrogen isotopes indicate that the spring water has not been subject to evaporation and in combination with Na/Cl ratios implies that recharge to the spring systems is via coastal precipitation. Although rainfall in the Cape is usually modelled on orographic rainfall, δ18O and δ2H values of some rainfall samples are strongly positive indicating a stratiform component as well. Comparing the spring water δ18O and δ2H values with that of local rainfall, indicates that the springs are likely derived from continuous bulk recharge over the immediate hinterland to the springs and not through large and/or heavy downpours. Noble gas concentrations, combined with tritium and radiocarbon activities indicate that the residence time of the TMG groundwater in this area is decadal in age with a probable maximum upper limit of ∼40 years. This residence time is probably a reflection of the slow flow rate through the fractured rock aquifer and hence indicates that the interconnectedness of the fractures is the most important factor controlling groundwater flow. The short residence time of the groundwater suggest that recharge to the springs and the Table Mountain Group Aquifer as a whole is

  15. Low-field MRI of laser polarized noble gas (United States)

    Tseng, C. H.; Wong, G. P.; Pomeroy, V. R.; Mair, R. W.; Hinton, D. P.; Hoffmann, D.; Stoner, R. E.; Hersman, F. W.; Cory, D. G.; Walsworth, R. L.


    NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

  16. MECRIS A compact ECRIS for ionization of noble gas radioisotopes at ISOLDE

    CERN Document Server

    Wenander, Fredrik


    The development of electron cyclotron resonance ion source (ECRIS) for singly charged radioactive gases at ISOLDE/CERN was analyzed. The radioisotopes were produced by fission, spallation and fragmentation reactions which were induced by high-energy protons. It was observed that Mono ECRIS (MECRIS) ISOLIDE was intended for light noble gases with low ionization efficiency in ordinary plasma ion sources. The results show that ionization efficiencies for He and Xe injected through calibrated leak were less than 0.1 and 5%-10% which were similar to standard ISOLDE plasma ion source. (Edited abstract) 11 Refs.

  17. Hydrogeochemical data for thermal and nonthermal waters and gases of the Valles Caldera- southern Jemez Mountains region, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Shevenell, L.; Goff, F.; Vuataz, F.; Trujillo, P.E. Jr.; Counce, D.; Janik, C.J.; Evans, W.


    This report presents field, chemical, gas, and isotopic data for thermal and nonthermal waters of the southern Jemez Mountains, New Mexico. This region includes all thermal and mineral waters associated with Valles Caldera and many of those located near the Nacimiento Uplift, north of San Ysidro. Waters of the region can be categorized into five general types: (1) surface and near-surface meteoric waters; (2) acid-sulfate waters at Sulphur Springs (Valles Caldera); (3) thermal meteoric waters in the ring fracture zone (Valles Caldera); (4) deep geothermal waters of the Baca geothermal field and derivative waters in the Soda Dam and Jemez Springs area (Valles Caldera); and (5) mineralized waters near San Ysidro. Some waters display chemical and isotopic characteristics intermediate between the types listed. Data in this report will help in interpreting the geothermal potential of the Jemez Mountains region and will provide background for investigating problems in hydrology, structural geology, hydrothermal alterations, and hydrothermal solution chemistry.

  18. Noble Gas Surface Flux Simulations And Atmospheric Transport

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, Charles R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sun, Yunwei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Signatures from underground nuclear explosions or UNEs are strongly influenced by the containment regime surrounding them. The degree of gas leakage from the detonation cavity to the surface obviously affects the magnitude of surface fluxes of radioxenon that might be detected during the course of a Comprehensive Test Ban Treaty On-Site Inspection. In turn, the magnitude of surface fluxes will influence the downwind detectability of the radioxenon atmospheric signature from the event. Less obvious is the influence that leakage rates have on the evolution of radioxenon isotopes in the cavity or the downwind radioisotopic measurements that might be made. The objective of this letter report is to summarize our attempt to better understand how containment conditions affect both the detection and interpretation of radioxenon signatures obtained from sampling at the ground surface near an event as well as at greater distances in the atmosphere. In the discussion that follows, we make no attempt to consider other sources of radioactive noble gases such as natural backgrounds or atmospheric contamination and, for simplicity, only focus on detonation-produced radioxenon gases. Summarizing our simulations, they show that the decay of radioxenon isotopes (e.g., Xe-133, Xe-131m, Xe-133m and Xe-135) and their migration to the surface following a UNE means that the possibility of detecting these gases exists within a window of opportunity. In some cases, seeps or venting of detonation gases may allow significant quantities to reach the surface and be released into the atmosphere immediately following a UNE. In other release scenarios – the ones we consider here – hours to days may be required for gases to reach the surface at detectable levels. These release models are most likely more characteristic of “fully contained” events that lack prompt venting, but which still leak gas slowly across the surface for periods of months.

  19. Reactions of Criegee Intermediates with Non-Water Greenhouse Gases: Implications for Metal Free Chemical Fixation of Carbon Dioxide. (United States)

    Kumar, Manoj; Francisco, Joseph S


    High-level theoretical calculations suggest that a Criegee intermediate preferably interacts with carbon dioxide compared to two other greenhouse gases, nitrous oxide and methane. The results also suggest that the interaction between Criegee intermediates and carbon dioxide involves a cycloaddition reaction, which results in the formation of a cyclic carbonate-type adduct with a barrier of 6.0-14.0 kcal/mol. These results are in contrast to a previous assumption that the reaction occurs barrierlessly. The subsequent decomposition of the cyclic adduct into formic acid and carbon dioxide follows both concerted and stepwise mechanisms. The latter mechanism has been overlooked previously. Under formic acid catalysis, the concerted decomposition of the cyclic carbonate may be favored under tropospheric conditions. Considering that there is a strong nexus between carbon dioxide levels in the atmosphere and global warming, the high reactivity of Criegee intermediates could be utilized for designing efficient carbon capture technologies.

  20. Water soluble inorganic trace gases and related aerosol compounds in the tropical boundary layer. An analysis based on real time measurements at a pasture site in the Amazon Basin

    NARCIS (Netherlands)

    Trebs, I.


    This dissertation investigates the behavior of water-soluble inorganic trace gases and related aerosol species in the tropical boundary layer. Mixing ratios of ammonia (NH3), nitric acid (HNO3), nitrous acid (HONO), hydrochloric acid (HCl), sulfur dioxide (SO;,) and the corresponding water-soluble

  1. The release of trapped gases from amorphous solid water films. I. "Top-down" crystallization-induced crack propagation probed using the molecular volcano. (United States)

    May, R Alan; Smith, R Scott; Kay, Bruce D


    In this (Paper I) and the companion paper (Paper II; R. May, R. Smith, and B. Kay, J. Chem. Phys. 138, 104502 (2013)), we investigate the mechanisms for the release of trapped gases from underneath amorphous solid water (ASW) films. In prior work, we reported the episodic release of trapped gases in concert with the crystallization of ASW, a phenomenon that we termed the "molecular volcano." The observed abrupt desorption is due to the formation of cracks that span the film to form a connected pathway for release. In this paper, we utilize the "molecular volcano" desorption peak to characterize the formation of crystallization-induced cracks. We find that the crack length distribution is independent of the trapped gas (Ar, Kr, Xe, CH4, N2, O2, or CO). Selective placement of the inert gas layer is used to show that cracks form near the top of the film and propagate downward into the film. Isothermal experiments reveal that, after some induction time, cracks propagate linearly in time with an Arrhenius dependent velocity corresponding to an activation energy of 54 kJ∕mol. This value is consistent with the crystallization growth rates reported by others and establishes a direct connection between crystallization growth rate and the crack propagation rate. A two-step model in which nucleation and crystallization occurs in an induction zone near the top of the film followed by the propagation of a crystallization∕crack front into the film is in good agreement with the temperature programmed desorption results.


    Directory of Open Access Journals (Sweden)

    Marian MANOLESCU


    Full Text Available Disputes about the opportunity to introduce competence-based education are increasingly present in terms of educational policies and strategies. Obviously, in the last decade and a half, several countries have introduced competence based education. Although specific knowledge acquisition should be an essential component of student learning, assessing such knowledge in adult life depends largely on the individual purchase of more general concepts and skills. The article discusses pragmatic knowledge and noble knowledge. This is a collective dilemma, to the extent that the education system lives in the tension between the two logics. The two positions or divergent attitudes can coexist as long ast hey do not become extremist. Educational dilemma is especially now a priority.

  3. Subsurface Noble Gas Sampling Manual

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sun, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    The intent of this document is to provide information about best available approaches for performing subsurface soil gas sampling during an On Site Inspection or OSI. This information is based on field sampling experiments, computer simulations and data from the NA-22 Noble Gas Signature Experiment Test Bed at the Nevada Nuclear Security Site (NNSS). The approaches should optimize the gas concentration from the subsurface cavity or chimney regime while simultaneously minimizing the potential for atmospheric radioxenon and near-surface Argon-37 contamination. Where possible, we quantitatively assess differences in sampling practices for the same sets of environmental conditions. We recognize that all sampling scenarios cannot be addressed. However, if this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from the scenario assumed here, it will have achieved its goal.

  4. Recovery and use of fission product noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.


    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value. (DLC)

  5. 21 CFR 872.3060 - Noble metal alloy. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that...

  6. The influence of humidification and temperature differences between inlet gases on water transport through the membrane of a proton exchange membrane fuel cell (United States)

    Huang, Kuan-Jen; Hwang, Sheng-Jye; Lai, Wei-Hsiang


    This paper discusses the effects of humidification and temperature differences of the anode and cathode on water transport in a proton exchange membrane fuel cell. Heaters are used to cause a difference in gas temperature between two electrodes before the gases enter the fuel cell. The results show that when the temperature of the cathode is higher than that of the anode, the electro-osmotic drag is suppressed. In contrast, when the temperature of the anode is higher than that of cathode, it is enhanced. These effects are more significant when the temperature difference between the anode and cathode is greater. The same trends are seen with back diffusion. Three cases are tested, and the results show that the suppression due to the temperature difference occurs even when the relative humidity is low at the hotter side. The water transport tendencies of electro-osmotic drag and back diffusion in different situations can be expressed as dominant percentages calculated by the water masses collected at the anode and cathode. The suppression effect due to the temperature difference is relatively insignificant with regard to back diffusion compared to electro-osmosis, so water tends to accumulate on the anode rather than the cathode side.

  7. Physiological response of rats to delivery of helium and xenon: implications for hyperpolarized noble gas imaging (United States)

    Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)


    The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.

  8. Numerical Investigation of the Main Characteristics of Heat and Mass Transfer while Heating the Heterogeneous Water Droplet in the Hot Gases

    Directory of Open Access Journals (Sweden)

    Piskunov Maxim V.


    Full Text Available The processes of heat and evaporation of heterogeneous water droplet with solid (by the example of carbon inclusion in hot (from 800 K to 1500 K gases were investigated by the developed models of heat and mass transfer. We defined the limited conditions, characteristics of the droplet and the gas medium which are sufficient for implementing the “explosive” destruction of heterogeneous droplet due to intensive vaporization on an inner interface, and intensive evaporation of liquid from an external (free droplet surface. The values of the main characteristic of the process (period from start of heating to “explosive” destruction obtained in response to using various heat and mass transfer models were compared.

  9. The 1997 El Niño impact on clouds, water vapour, aerosols and reactive trace gases in the troposphere, as measured by the Global Ozone Monitoring Experiment

    Directory of Open Access Journals (Sweden)

    D. Loyola


    Full Text Available The El Niño event of 1997/1998 caused dry conditions over the Indonesian area that were followed by large scale forest and savannah fires over Kalimantan, Sumatra, Java, and parts of Irian Jaya. Biomass burning was most intense between August and October 1997, and large amounts of ozone precursors, such as nitrogen oxides, carbon monoxide and hydrocarbons were emitted into the atmosphere. In this work, we use satellite measurements from the Global Ozone Monitoring Experiment (GOME sensor to study the teleconnections between the El Niño event of 1997 and the Indonesian fires, clouds, water vapour, aerosols and reactive trace gases (nitrogen dioxide, formaldehyde and ozone in the troposphere.

  10. Using noble gas tracers to estimate residual CO2 saturation in the field: results from the CO2CRC Otway residual saturation and dissolution test (United States)

    LaForce, T.; Ennis-King, J.; Paterson, L.


    Residual CO2 saturation is a critically important parameter in CO2 storage as it can have a large impact on the available secure storage volume and post-injection CO2 migration. A suite of single-well tests to measure residual trapping was conducted at the Otway test site in Victoria, Australia during 2011. One or more of these tests could be conducted at a prospective CO2 storage site before large-scale injection. The test involved injection of 150 tonnes of pure carbon dioxide followed by 454 tonnes of CO2-saturated formation water to drive the carbon dioxide to residual saturation. This work presents a brief overview of the full test sequence, followed by the analysis and interpretation of the tests using noble gas tracers. Prior to CO2 injection krypton (Kr) and xenon (Xe) tracers were injected and back-produced to characterise the aquifer under single-phase conditions. After CO2 had been driven to residual the two tracers were injected and produced again. The noble gases act as non-partitioning aqueous-phase tracers in the undisturbed aquifer and as partitioning tracers in the presence of residual CO2. To estimate residual saturation from the tracer test data a one-dimensional radial model of the near-well region is used. In the model there are only two independent parameters: the apparent dispersivity of each tracer and the residual CO2 saturation. Independent analysis of the Kr and Xe tracer production curves gives the same estimate of residual saturation to within the accuracy of the method. Furthermore the residual from the noble gas tracer tests is consistent with other measurements in the sequence of tests.

  11. Water and wastewater services: a contribution to greenhouse gases mitigation. Methodologies and experience feedback; Service d'eau et d'assainissement: contribuer a reduire les emissions de gaz a effet de serre

    Energy Technology Data Exchange (ETDEWEB)

    Maugendre, J.P. [Lyonnaise des Eaux, 75 - Paris (France); Arama, G. [Veolia Eau, 75 - Paris (France); Reungoat, E. [Saur - Les Cyclades, 78 - Guyancourt (France); Schafer, E. [SIAAP, 75 - Paris (France); Ginsburger, C. [FNCCR, 75 - Paris (France); Duguet, J.P. [Eau de Paris, 75 - Paris (France); Gourdon, T. [Ademe, 49 - Angers (France); Senante, E. [Suez Environnement, 78 - Le Pecq (France); Hassine, M. [Sade - CGTH, 75 - Paris (France)


    Energy efficiency and contribution to reducing emissions of greenhouse gases (GHGs) are at the heart of environmental concerns of communities and the public. Without waiting for the regulations that may affect them in the future on climate/energy, water and sanitation services will need to explore options aimed at saving energy, producing renewable energy and reducing direct or indirect emissions of greenhouse gases on their territory. In terms of controlling emissions of greenhouse gases, the results of initial assessments of GHGs emissions (including some made with the French 'Bilan Carbone' model, developed by the French Environment and Energy Management Agency - Ademe) help to identify the importance of emissions related to the management of water and wastewater services, to propose action plans to reduce them, and contribute to reducing emissions of other local actors through the creation of new renewable energy sources. A joint working group of Astee (French Scientific and Technical Association for Water and Environment) water and wastewater commissions prepared some guidelines for calculating emissions of greenhouse gases of water and wastewater services. These guidelines have been made available on the association web-site since September 2009. This article takes stock on the initial feedbacks relating to its implementation among operators of water and wastewater services. (authors)

  12. Polymer-noble metal nanocomposites: Review

    CSIR Research Space (South Africa)

    Folarin, OM


    Full Text Available Polymer-noble metal nanocomposites have been extensively investigated due to their potential ability to provide materials with novel mechanical, electronic or chemical behaviour for technological applications. Many preparative procedures have been...

  13. A Review on Preferential Oxidation of Carbon Monoxide in Hydrogen Rich Gases

    Directory of Open Access Journals (Sweden)

    A. Mishra


    Full Text Available In this review, recent works on the preferential oxidation of carbon monoxide in hydrogen rich gases for fuel cell applications are summarized. H2 is used as a fuel for polymer-electrolyte membrane fuel cell (PEMFC. It is produced by reforming of natural gas or liquid fuels followed by water gas shift reaction. The produced gas consists of H2, CO, and CO2. In which CO content is around 1%, which is highly poisonous for the Pt anode of the PEMFC so that further removal of CO is needed. Catalytic preferential oxidation of CO (CO-PROX is one of the most suitable methods of purification of H2 because of high CO conversion rate at low temperature range, which is preferable for PEMFC operating conditions. Catalysts used for COPROX are mainly noble metal based; gold based and base metal oxide catalysts among them Copper-Ceria based catalysts are the most appropriate due to its low cost, easy availability and result obtained by these catalysts are comparable with the conventional noble metal catalysts. Copyright © 2011 BCREC UNDIP. All rights reserved(Received: 22nd October 2010, Revised: 12nd January 2011, Accepted: 19th January 2011[How to Cite: A. Mishra, R. Prasad. (2011. A Review on Preferential Oxidation of Carbon Monoxide in Hydrogen Rich Gases. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (1: 1-14. doi:10.9767/bcrec.][How to Link / DOI: || or local:] | View in 

  14. Solubility of natural gases in water under high pressure; Solubilite des gaz naturels dans l`eau a pression elevee

    Energy Technology Data Exchange (ETDEWEB)

    Dhima, A.


    Under high pressure (up to 1200 bar) and high temperature (up to 200 deg C) petroleum reservoir conditions the hydrocarbon-water mutual solubilities may become important. Under such conditions, the prediction of hydrocarbon water solubilities is a challenge for petroleum engineers. Indeed, very few studies have been done ar pressures higher that 700 bars. New solubility data for methane, ethane, n-butane, CO{sub 2} and their mixtures in pure water were obtained at 344.25 K and from 2.5 to 100 MPa. The results agree very well with those of the literature in the case of pure hydrocarbons in water, but differ for the hydrocarbon mixtures. A rigorous thermodynamic analysis allows the elaboration of a model that combines a cubic equation of state (Peng-Robinson with k{sub ij} given in literature) with the Henry`s law approach. The (P,T) functional form of Henry`s constant is given by the Krichevsky-Kasarnovsky equation which involves two important parameters: partial molar volume at infinite dilution and Henry`s constant at the vapour pressure of water. For a given solute both parameters are only functions of temperature. A critical selection of binary solubility data for a large number of solutes has been used as a basis for a new correlation for calculating both this partial molar volume and the corresponding Henry`s constants as a function of temperature. (author) 169 refs.

  15. A combined noble gas and {sup 40}Ar-{sup 39}Ar study of Salt Lake Crater xenolith SL322 from Oahu, Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Trieloff, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Rocholl, A. [Heidelberg Univ. (Germany). Mineralogisch-Petrographisches Inst.; Jessberger, E.K. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)]|[Muenster Univ. (Germany). Inst. fuer Planetologie


    The microdistribution of noble gases in a garnet pyroxenite nodule from Salt Lake Crater (SLC), Oahu, Hawaii, was investigated by a detailed step-heating and -crushing analysis and a {sup 40}Ar-{sup 39}Ar-study. A noble gas component with MORB type argon, helium and neon resides in CO{sub 2}-rich fluid inclusions trapped in <30 km depth. This component was most probably derived from the nephelinitic SLC host magma and confirms the dominance of MORB type noble gases in the late post-erosional magmatic stages of Hawaiian volcanism, as suggested previsouly (Kurz et al., 1983; Valbracht et al., 1996). A second previously detected (Rocholl et al., 1996) low {sup 40}Ar/{sup 36}Ar ({proportional_to}5000) component turned out to be associated with two different reservoirs. The larger reservoir is most probably related to garnet, the other one is associated with low retentive sites containing few K and Cl and could not yet be adequately identified. The low {sup 40}Ar/{sup 36}Ar ({proportional_to}5000) component hosted by garnet can be interpreted as a mixture of MORB and plume type noble gas components with specific {sup 4}He/{sup 40}Ar ratios. The results demonstrate the complexity of the microdistribution of noble gases in ultramafic nodules and allow insight into plume induced metasomatism of the Hawaiian lithosphere. (orig.)

  16. Real-time measurements of ammonia, acidic trace gases and water-soluble inorganic aerosol species at a rural site in the Amazon Basin

    Directory of Open Access Journals (Sweden)

    I. Trebs


    Full Text Available We measured the mixing ratios of ammonia (NH3, nitric acid (HNO3, nitrous acid (HONO, hydrochloric acid (HCl, sulfur dioxide (SO2 and the corresponding water-soluble inorganic aerosol species, ammonium (NH4+, nitrate (NO3-, nitrite (NO2-, chloride (Cl- and sulfate (SO42-, and their diel and seasonal variations at a pasture site in the Amazon Basin (Rondônia, Brazil. This study was conducted within the framework of LBA-SMOCC (Large Scale Biosphere Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall and Climate: Aerosols from Biomass Burning Perturb Global and Regional Climate. Sampling was performed from 12 September to 14 November 2002, extending from the dry season (extensive biomass burning activity, through the transition period to the wet season (background conditions. Measurements were made continuously using a wet-annular denuder (WAD in combination with a Steam-Jet Aerosol Collector (SJAC followed by suitable on-line analysis. A detailed description and verification of the inlet system for simultaneous sampling of soluble gases and aerosol compounds is presented. Overall measurement uncertainties of the ambient mixing ratios usually remained below 15%. The limit of detection (LOD was determined for each single data point measured during the field experiment. Median LOD values (3σ-definition were ≤0.015ppb for acidic trace gases and aerosol anions and ≤0.118ppb for NH3 and aerosol NH4+. Mixing ratios of acidic trace gases remained below 1ppb throughout the measurement period, while NH3 levels were an order of magnitude higher. Accordingly, mixing ratios of NH4+ exceeded those of other inorganic aerosol contributors by a factor of 4 to 10. During the wet season, mixing ratios decreased by nearly a factor of 3 for all compounds compared to those observed when intensive biomass burning took place. Additionally, N-containing gas and aerosol species featured pronounced diel variations. This is attributed to strong


    DEFF Research Database (Denmark)


    The present invention concerns a chemical process for preparing nanoparticles of an alloy comprising both a noble metal, such as platinum, and a non-noble transition or lanthanide metal, such as yttrium, gadolinium or terbium. The process is carried out by reduction with hydrogen and removal...

  18. A comparative study of vertical flow and free-water surface constructed wetlands for low C/N ratio domestic wastewater treatment and its greenhouse gases emission (United States)

    Xu, K.; Liu, C.; Ebie, Y.; Inamori, Y.


    Constructed wetland (CW) systems are reliable, flexible in design, and can be built, operated, and maintained at lower costs compared to conventional methods of chemical treatment. Therefore, CW systems are widely used for controlling water-body eutrophication as an ease-operation and cost-effective ecological technology in developing countries. However, growing attention has been directed to its greenhouse side-effect and global-warming potential in recent years. In this study, two typical constructed wetlands: Vertical flow (VF) and Free-water surface (FWS) constructed wetlands were used not only to compare the nutrients removal performance for treatment of low C/N ratio loading domestic wastewater, but also to investigate and compare their CH4 and N2O greenhouse gases emission characteristics. The results indicated that the VF CW showed a comparatively good performance for nitrogen and phosphorus removal than FWS constructed wetland, which was 98.5, 95.9, 93.2 and 90.7 percent for BOD5, SS, NH4-N and TP under 6 days HRT, respectively. It was found that the FWS CW had the higher tendency to emit CH4 than the VF CW during four seasons of one year.

  19. An automated analyzer to measure surface-atmosphere exchange fluxes of water soluble inorganic aerosol compounds and reactive trace gases. (United States)

    Thomas, Rick M; Trebs, Ivonne; Otjes, René; Jongejan, Piet A C; Ten Brink, Harry; Phillips, Gavin; Kortner, Michael; Meixner, Franz X; Nemitz, Eiko


    Here, we present a new automated instrument for semicontinuous gradient measurements of water-soluble reactive trace gas species (NH3, HNO3, HONO, HCl, and SO2) and their related aerosol compounds (NH4+, NO3-, Cl-, SO4(2-)). Gas and aerosol samples are collected simultaneously at two heights using rotating wet-annular denuders and steam-jet aerosol collectors, respectively. Online (real-time) analysis using ion chromatography (IC) for anions and flow injection analysis (FIA) for NH4+ and NH3 provide a half-hourly averaged gas and aerosol gradients within each hour. Through the use of syringe pumps, IC preconcentration columns, and high-quality purified water, the system achieves detection limits (3sigma-definition) under field conditions of typically: 136/207,135/114, 29/ 22,119/92, and 189/159 ng m(-3) for NH3/NH4+, HNO3/NO3-, HONO/ NO2-, HCl/Cl- and SO2/SO4(2-), respectively. The instrument demonstrates very good linearity and accuracy for liquid and selected gas phase calibrations over typical ambient concentration ranges. As shown by examples from field experiments, the instrument provides sufficient precision (3-9%), even at low ambient concentrations, to resolve vertical gradients and calculate surface-atmosphere exchange fluxes undertypical meteorological conditions of the atmospheric surface layer using the aerodynamic gradient technique.

  20. [Summer Greenhouse Gases Exchange Flux Across Water-air Interface in Three Water Reservoirs Located in Different Geologic Setting in Guangxi, China]. (United States)

    Li, Jian-hong; Pu, Jun-bing; Sun, Ping-an; Yuan, Dao-xian; Liu, Wen; Zhang, Tao; Mo, Xue


    Due to special hydrogeochemical characteristics of calcium-rich, alkaline and DIC-rich ( dissolved inorganic carbon) environment controlled by the weathering products from carbonate rock, the exchange characteristics, processes and controlling factors of greenhouse gas (CO2 and CH4) across water-air interface in karst water reservoir show obvious differences from those of non-karst water reservoir. Three water reservoirs (Dalongdong reservoir-karst reservoir, Wulixia reservoir--semi karst reservoir, Si'anjiang reservoir-non-karst reservoir) located in different geologic setting in Guangxi Zhuang Autonomous Region, China were chosen to reveal characteristics and controlling factors of greenhouse gas exchange flux across water-air interface. Two common approaches, floating chamber (FC) and thin boundary layer models (TBL), were employed to research and contrast greenhouse gas exchange flux across water-air interface from three reservoirs. The results showed that: (1) surface-layer water in reservoir area and discharging water under dam in Dalongdong water reservoir were the source of atmospheric CO2 and CH4. Surface-layer water in reservoir area in Wulixia water reservoir was the sink of atmospheric CO2 and the source of atmospheric CH4, while discharging water under dam was the source of atmospheric CO2 and CH4. Surface-layer water in Si'anjiang water reservoir was the sink of atmospheric CO2 and source of atmospheric CH4. (2) CO2 and CH4 effluxes in discharging water under dam were much more than those in surface-layer water in reservoir area regardless of karst reservoir or non karst reservoir. Accordingly, more attention should be paid to the CO2 and CH4 emission from discharging water under dam. (3) In the absence of submerged soil organic matters and plants, the difference of CH4 effluxes between karst groundwater-fed reservoir ( Dalongdong water reservoir) and non-karst area ( Wulixia water reservoir and Si'anjiang water reservoir) was less. However, CO2

  1. Measurements of the conduction of heat in water vapor, nitrogen and mixtures of these gases in an extended temperature range (United States)

    Frohn, A.; Westerdorf, M.

    Experimental and analytical results are presented from trials with heat conduction in water vapor, nitrogen, and mixtures of the two in a cylindrical heat transfer cell. The pressures examined ranged from 100-0.01 mbar, corresponding to Knudsen numbers of 0.01-100. Formulations are defined for the continuum conditions, the free molecule conditions, the transition region, and the momentum equation solution. Experimentation with an instrumented configuration of an inner and outer cylinder over the temperature range 300-725 K is described, noting the use of a vacuum around the inner, gas-filled container in order to measure the radiative heat losses. The results are useful for predicting heat transfer in high altitude flight or among small droplets in natural fogs, cooling towers, and combustion chambers.

  2. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites (United States)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.


    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

  3. Optimizing detection of noble gas emission at a former UNE site: sample strategy, collection, and analysis (United States)

    Kirkham, R.; Olsen, K.; Hayes, J. C.; Emer, D. F.


    Underground nuclear tests may be first detected by seismic or air samplers operated by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). After initial detection of a suspicious event, member nations may call for an On-Site Inspection (OSI) that in part, will sample for localized releases of radioactive noble gases and particles. Although much of the commercially available equipment and methods used for surface and subsurface environmental sampling of gases can be used for an OSI scenario, on-site sampling conditions, required sampling volumes and establishment of background concentrations of noble gases require development of specialized methodologies. To facilitate development of sampling equipment and methodologies that address OSI sampling volume and detection objectives, and to collect information required for model development, a field test site was created at a former underground nuclear explosion site located in welded volcanic tuff. A mixture of SF-6, Xe127 and Ar37 was metered into 4400 m3 of air as it was injected into the top region of the UNE cavity. These tracers were expected to move towards the surface primarily in response to barometric pumping or through delayed cavity pressurization (accelerated transport to minimize source decay time). Sampling approaches compared during the field exercise included sampling at the soil surface, inside surface fractures, and at soil vapor extraction points at depths down to 2 m. Effectiveness of various sampling approaches and the results of tracer gas measurements will be presented.

  4. Noble Metal Nanoparticles for Biosensing Applications (United States)

    Doria, Gonçalo; Conde, João; Veigas, Bruno; Giestas, Leticia; Almeida, Carina; Assunção, Maria; Rosa, João; Baptista, Pedro V.


    In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios) that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory. PMID:22438731

  5. Results report. Sampling and analyses of gases and microorganisms in the water from MINICAN in 2007, 2008 and 2010

    Energy Technology Data Exchange (ETDEWEB)

    Lydmark, Sara; Hallbeck, Lotta (Microbial Analytics Sweden AB (Sweden))


    The MINICAN project is located at the depth of 450 m in the Aespoe Hard Rock Laboratory and was initiated to study how corrosion of the cast iron insert inside a perforated copper canister would evolve with time. Miniature canisters with different perforations and with and without bentonite buffer in steel cages were installed and monitored. Samples for microbiological and gas composition together with samples for groundwater chemistry have been analysed at three occasions in 2007, 2008 and 2010. The results show how the microbial populations outside the canisters have evolved from a mixture of microorganism able to grow on organic material, like heterotrophic organisms, and acetogens that grow on hydrogen gas and carbon dioxide in 2007, to populations with a large proportion of sulphate-reducing bacteria in 2010. The highest number of sulphate-reducing bacteria was found in MINICAN experiment A02C, canister with one hole at the top of the copper canister, in 2010 with 2.4 x 104 mL-1 followed by 8 x 103 mL-1 in A03 (hole in the bottom of the canister) and 7 x 103 mL-1 in A06 (two holes at the top and no bentonite). The numbers of culturable heterotrophic bacteria were between 200 and 530 mL-1 in the experiments with bentonite in 2007 but below detection in all experiments in 2010. The same trend was shown for acetogenes. Measurable amounts of hydrogen gas were found in all experiments at all sampling occasions. There was no general trend for the amounts of hydrogen but there was an increase in three of the experiments and in the groundwater outside MINICAN. It was found that the water chemistry differed between A06 and A02-A04 experiment by higher sulphate and chloride concentrations in A06 compared to the others. By plotting the concentrations of chloride, sulphate against time, a decrease in sulphate concentration was found in all canister experiments. The chloride concentrations were stable during the same period. On the other hand, an increase in sulphate

  6. Adsorption properties of fission gases Xe and Kr on pristine and doped graphene: A first principle DFT study (United States)

    Vazhappilly, Tijo; Ghanty, Tapan K.; Jagatap, B. N.


    Graphene has excellent adsorption properties due to large surface area and has been used in applications related to gas sorption and separation. The separation of radioactive noble gases using graphene is an interesting area of research relevant to nuclear waste management. Radioactive noble gases Xe and Kr are present in the off-gas streams from nuclear fission reactors and spent nuclear fuel reprocessing plants. The entrapment of these volatile fission gases is important in the context of nuclear safety. The separation of Xe from Kr is extremely difficult, and energy intensive cryogenic distillation is generally employed. Physisorption based separation techniques using porous materials is a cost effective alternative to expensive cryogenic distillation. Thus, adsorption of noble gases on graphene is relevant for fundamental understanding of physisorption process. The properties of graphene can be tuned by doping and incorporation of defects. In this regard, we study the binding affinity of Xe and Kr in pristine and doped graphene sheets. We employ first principle calculations using density functional theory, corrected for dispersion interactions. The structural parameters obtained from the current study show excellent agreement with the available theoretical and experimental observations on similar systems. Noble gas adsorption energies on pristine graphene match very well with the available literature. Our results show that the binding energy of fission gases Xe and Kr on graphene can be considerably improved through doping the lattice with a heteroatom.

  7. Theory of warm ionized gases: equation of state and kinetic Schottky anomaly. (United States)

    Capolupo, A; Giampaolo, S M; Illuminati, F


    Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments.

  8. Apparatus for preparing a solution of a hyperpolarized noble gas for NMR and MRI analysis (United States)

    Pines, Alexander [Berkeley, CA; Budinger, Thomas [Berkeley, CA; Navon, Gil [Ramat Gan, IL; Song, Yi-Qiao [Berkeley, CA; Appelt, Stephan [Waiblingen, DE; Bifone, Angelo [Rome, IT; Taylor, Rebecca [Berkeley, CA; Goodson, Boyd [Berkeley, CA; Seydoux, Roberto [Berkeley, CA; Room, Toomas [Albany, CA; Pietrass, Tanja [Socorro, NM


    The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

  9. Handbook of purified gases

    CERN Document Server

    Schoen, Helmut


    Technical gases are used in almost every field of industry, science and medicine and also as a means of control by government authorities and institutions and are regarded as indispensable means of assistance. In this complete handbook of purified gases the physical foundations of purified gases and mixtures as well as their manufacturing, purification, analysis, storage, handling and transport are presented in a comprehensive way. This important reference work is accompanied with a large number of Data Sheets dedicated to the most important purified gases.  

  10. On a cryogenic noble gas ion catcher

    NARCIS (Netherlands)

    Dendooven, P; Purushothaman, S; Gloos, K


    In situ purification of the gas used as stopping medium in a noble gas ion catcher by operating the device at low temperatures of 60-150 K was investigated. Alpha-decay recoil ions from a Ra-223 source served as energetic probes. The combined ion survival and transport efficiencies for Rn-219 ions

  11. Gases (CH4, CO2 and N2 and pore water chemistry in the surface sediments of Lake Orta, Italy: acidification effects on C and N gas cycling

    Directory of Open Access Journals (Sweden)

    Donald D. ADAMS


    Full Text Available Lake Orta, a subalpine, warm monomictic lake in northwestern Italy was heavily polluted from rayon factory discharges of ammonium and copper since 1926. In the 1950s accumulations of contaminants resulted in whole lake pHs of 3.8-4.0 from ammonium oxidation. Partial remediation started in the 1950s, but by 1985-89 the water remained acidified at pHs of 4.0. Artificial liming (14,500 t in 1989-90 resulted in improved water quality and substantial recovery of the biological community. Sediment gases, sampled in 1989 before liming, from the lake's four basins showed severe inhibition of methanogenesis (CH4 = 0.0-0.15 mM in the surface sediments (0.5-5 cm of the southern basin, location of the plant effluent, as compared to the deep central and northern basins (0.9-1.4 mM. Four years after liming, cores collected in 1994 near the 1989 southern basin sites showed a slight change in surface sediment methane (0.07-0.82 mM, yet suggested continual sediment toxicity, at least to carbon cycling through methanogenesis. Calculations of diffuse flux of CH4 at the sediment-water interface (SWI in 1989 were 6.6-7.4 mM m-2 day-1 for the central and northern basins and 0.13 for the southern basin. CH4 fluxes increased 16x to 2 mM m-2 day-1 in 1994 in the southern basin, possibly from remediation of near surface sediments. The impact of pollution on denitrification (formation of sediment N2 gas was not so obvious since two processes could counteract each other (high NO3 - stimulating denitrification versus possible negative effects from acidity and metals. The calculated flux of N2 from the southern basin sediments increased 5x four years after liming compared to the period of acidification, suggesting possible toxicity towards denitrifiers during the earlier period. Core overlying water (0.68 mM exhibited N2 concentrations close to saturation, while most surface sediments were twice as much (1.5 mM. Surface (0-6 cm sediment N2 was similar at most sites, with the

  12. Tracer Applications of Noble Gas Radionuclides in the Geosciences

    CERN Document Server

    Lu, Z -T; Smethie, W M; Sturchio, N C; Fischer, T P; Kennedy, B M; Purtschert, R; Severinghaus, J P; Solomon, D K; Tanhua, T; Yokochi, R


    The noble gas radionuclides, including 81Kr (half-life = 229,000 yr), 85Kr (11 yr), and 39Ar (269 yr), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide. We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times. Other scientific questions involving deeper circulation of fluids in the Earth's crust ...

  13. Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases (United States)

    Symonds, Robert B.; Poreda, Robert J.; Evans, William C.; Janik, Cathy J.; Ritchie, Beatrice E.


    Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, δ13C of CO2, δ13C of CH4, δ15N) compositions of virtually airfree gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ≤173°C fumaroles and springs at Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. The chemical and isotopic data generally point to magmatic (CO2, Ar, He), shallow crustal sedimentary (hereafter, SCS) (CO2, N2, CH4), crustal (He), and meteoric (N2, Ar) sources of volatiles. CH4 clearly comes from SCS rocks in the subvolcanic systems because CH4 cannot survive the higher temperatures of deeper potential sources. Further evidence for a SCS source for CH4 as well as for non-mantle CO2 and non-meteoric N2 comes from isotopic data that show wide variations between volcanoes that are spatially very close and similar isotopic signatures from volcanoes from very disparate areas. Our results are in direct opposition to many recent studies on other volcanic arcs (Kita and others, 1993; Sano and Marty, 1995; Fischer and others, 1998), in that they point to a dearth of subducted components of CO2 and N2 in the CRAA discharges. Either the CRAA volcanoes are fundamentally different from volcanoes in other arcs or we need to reevaluate the significance of subducted C and N recycling in convergent-plate volcanoes.

  14. Screening metal-organic frameworks for selective noble gas adsorption in air: effect of pore size and framework topology. (United States)

    Parkes, Marie V; Staiger, Chad L; Perry, John J; Allendorf, Mark D; Greathouse, Jeffery A


    The adsorption of noble gases and nitrogen by sixteen metal-organic frameworks (MOFs) was investigated using grand canonical Monte Carlo simulation. The MOFs were chosen to represent a variety of net topologies, pore dimensions, and metal centers. Three commercially available MOFs (HKUST-1, AlMIL-53, and ZIF-8) and PCN-14 were also included for comparison. Experimental adsorption isotherms, obtained from volumetric and gravimetric methods, were used to compare krypton, argon, and nitrogen uptake with the simulation results. Simulated trends in gas adsorption and predicted selectivities among the commercially available MOFs are in good agreement with experiment. In the low pressure regime, the expected trend of increasing adsorption with increasing noble gas polarizabilty is seen. For each noble gas, low pressure adsorption correlates with several MOF properties, including free volume, topology, and metal center. Additionally, a strong correlation exists between the Henry's constant and the isosteric heat of adsorption for all gases and MOFs considered. Finally, we note that the simulated and experimental gas selectivities demonstrated by this small set of MOFs show improved performance compared to similar values reported for zeolites.

  15. Blood Gases Test (United States)

    ... LDL Particle Testing (LDL-P) Lead Legionella Testing Leptin Levetiracetam Lipase Lipid Profile Lipoprotein (a) Lithium Liver ... such as asthma or chronic obstructive pulmonary disease (COPD) is suspected. Blood gases may also be used ...

  16. On Classical Ideal Gases

    National Research Council Canada - National Science Library

    Jacques Arnaud; Laurent Chusseau; Fabrice Philippe


      We show that the thermodynamics of ideal gases may be derived solely from the Democritean concept of corpuscles moving in vacuum plus a principle of simplicity, namely that these laws are independent...

  17. Kinetic theory of gases

    CERN Document Server

    Kauzmann, Walter


    Monograph and text supplement for first-year students of physical chemistry focuses chiefly on the molecular basis of important thermodynamic properties of gases, including pressure, temperature, and thermal energy. 1966 edition.

  18. Recycling of volatiles at subduction zones: Noble gas evidence from the Tabar-Lihir-Tanga-Feni arc of papua New Guinea (United States)

    Farley, Kenneth; Mcinnes, Brent; Patterson, Desmond


    Convergent margin processes play an important but poorly understood role in the distribution of terrestrial volatile species. For example, subduction processes filter volatiles from the subducting package, thereby restricting their return to the mantle. In addition, once extracted from the downgoing slab, volatiles become an essential component in the petrogenesis of island arc magmas. The noble gases, with their systematic variation in physical properties and diversity of radiogenic isotopes, should carry a uniquely valuable record of these processes. However, thus far studies of noble gases in arc volcanics have achieved only limited success in this regard. Subduction-related lavas and geothermal fluids carry (3)He/(4)He ratios equal to or slightly lower than those found in the depleted upper mantle source of mid-ocean ridge basalts. Apparently slab-derived helium (which should have (3)He/(4)He much less than MORB) is extensively diluted by MORB-like helium from the mantle wedge, making it difficult to use helium as a tracer of convergent margin processes. Interpretation of the heavier noble gases (Ne-Ar-Kr-Xe) in arc lavas has also proven difficult, because the lavas carry low noble gas concentrations and hence are subject to pervasive atmospheric contamination. The low noble gas concentrations may be a consequence of degassing in the high level magma chambers characteristic of arc stratovolcanos. We have recently initiated a project to better constrain the behavior of volatiles in subduction zones through geochemical studies of the tectonically unusual volcanoes of the Tabar-Lihir-Tanga-Feni (TLTF) arc in the Bismarck Archipelago, Papua New Guinea.

  19. Study of gases and volatiles in samples of underground water bodies in the State of Mexico; Estudio de gases y volatiles en muestras de cuerpos de agua subterranea en el Estado de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez R, N.; Segovia, N.; Cisniega, G.; Tamez, E. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)


    It was realized a preliminary study of radon and volatile organic compounds (VOC ) in spring water of the State of Mexico. The radon was determined by the liquid scintillation method and the VOC by gas chromatography coupled to mass spectroscopy. The radon concentration range was between 0.50 - 4.42 KBq/m{sup 3}. Its were found some VOC of probably anthropogenic origin. (Author)

  20. Noble gas solubility in silicate melts:a review of experimentation and theory, and implications regarding magma degassing processes

    Directory of Open Access Journals (Sweden)

    A. Paonita


    Full Text Available Noble gas solubility in silicate melts and glasses has gained a crucial role in Earth Sciences investigations and in the studies of non-crystalline materials on a micro to a macro-scale. Due to their special geochemical features, noble gases are in fact ideal tracers of magma degassing. Their inert nature also allows them to be used to probe the structure of silicate melts. Owing to the development of modern high pressure and temperature technologies, a large number of experimental investigations have been performed on this subject in recent times. This paper reviews the related literature, and tries to define our present state of knowledge, the problems encountered in the experimental procedures and the theoretical questions which remain unresolved. Throughout the manuscript I will also try to show how the thermodynamic and structural interpretations of the growing experimental dataset are greatly improving our understanding of the dissolution mechanisms, although there are still several points under discussion. Our improved capability of predicting noble gas solubilities in conditions closer to those found in magma has allowed scientists to develop quantitative models of magma degassing, which provide constraints on a number of questions of geological impact. Despite these recent improvements, noble gas solubility in more complex systems involving the main volatiles in magmas, is poorly known and a lot of work must be done. Expertise from other fields would be extremely valuable to upcoming research, thus focus should be placed on the structural aspects and the practical and commercial interests of the study of noble gas solubility.

  1. Non-noble metal fuel cell catalysts

    CERN Document Server

    Chen, Zhongwei; Zhang, Jiujun


    Written and edited by a group of top scientists and engineers in the field of fuel cell catalysts from both industry and academia, this book provides a complete overview of this hot topic. It covers the synthesis, characterization, activity validation and modeling of different non-noble metal and metalfree electrocatalysts for the reduction of oxygen, as well as their integration into acid or alkaline polymer exchange membrane (PEM) fuel cells and their performance validation, while also discussing those factors that will drive fuel cell commercialization. With its well-structured app

  2. Source gases: Concentrations, emissions, and trends (United States)

    Fraser, Paul J.; Harriss, Robert; Penkett, Stuart A.; Makide, Yoshihiro; Sanhueza, Eugenio; Alyea, Fred N.; Rowland, F. Sherwood; Blake, Don; Sasaki, Toru; Cunnold, Derek M.


    Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

  3. Equilibrium Molecular Interactions in Pure Gases

    Directory of Open Access Journals (Sweden)

    Boris I. Sedunov


    Full Text Available The equilibrium molecular interactions in pure real gases are investigated based on the chemical thermodynamics principles. The parallels between clusters in real gases and chemical compounds in equilibrium media have been used to improve understanding of the real gas structure. A new approach to the equilibrium constants for the cluster fractions and new methods to compute them and their significant parameters from the experimental thermophysical data are developed. These methods have been applied to some real gases, such as Argon and Water vapors and gaseous Alkanes. It is shown that the four-particle clusters make a noticeable contribution in the thermophysical properties of the equilibrium Water vapor. It is shown also that the effective bond energy for dimers in Alkanes linearly grows with the number of carbon atoms in the molecule.


    Directory of Open Access Journals (Sweden)

    Dušica Stojanović


    Full Text Available The greenhouse effect can be defined as the consequence of increased heating of the Earth's surface, as well as the lower atmosphere by carbon dioxide, water vapor, and other trace amounts gases. It is well-known that human industrial activities have released large amounts of greenhouse gases in the atmosphere, about 900 billion tons of carbon dioxide, and it is estimated that up to 450 billion are still in the atmosphere. In comparison to greenhouse gases water vapor is one of the greatest contributors to the greenhouse effect on Earth. Many projects, as does the PURGE project, have tendences to build on the already conducted research and to quantify the positive and negative impacts on health and wellbeing of the population with greenhouse gas reduction strategies that are curently being implemented and should be increasingly applied in various sectors and urban areas, having offices in Europe, China and India.

  5. Variable flip angle schedules in bSSFP imaging of hyperpolarized noble gases. (United States)

    Deppe, Martin H; Wild, Jim M


    Balanced steady-state free precession imaging sequences provide signal-to-noise ratio benefits for MRI of hyperpolarized nuclei. Hyperpolarized magnetization decays during the imaging sequence to thermal equilibrium, effectively necessitating imaging in a transient state characterized by nonconstant transverse magnetization and k-space filtering when using constant flip angles. This work presents an analytical method for calculation of variable flip angle schedules which maintain constant transverse magnetization in balanced steady-state free precession imaging of hyperpolarized nuclei. The approach is based on direct inversion of the Bloch equations and does not require any numerical optimization. Input parameters are pulse sequence timings and effective relaxation times, which take diffusion of hyperpolarized gas in imaging gradients into account. Provision of constant transverse magnetization is demonstrated in phantom experiments and human lung imaging using hyperpolarized (3) He. The benefit of a flat k-space filter is demonstrated by reduced blurring in (3) He and digital phantom data, and high quality (3) He ventilation images from human lungs are obtained. Copyright © 2011 Wiley-Liss, Inc.

  6. Noble gases in LEW88516 shergottite: Evidence for exposure age pairing with ALH77005 (United States)

    Bogard, D. D.; Garrison, D. H.


    LEW88516 contains excess amounts of radiogenic Ar-40 and Xe-129 that are slightly greater than those observed in ALH77005, but in the same relative proportion as much larger excesses observed in EET79001. Cosmogenic He-3 and Ne-21 abundances in LEW88516 are very similar to those for ALH77005 and are consistent with a common initiation of cosmic ray exposure -2.8 Myr ago for four of the five shergottites. Exposure of these four shergottites could have been under different shielding in a common meteoroid, or in several objects.

  7. Quasi-phase-matching for third harmonic generation in noble gases employing ultrasound. (United States)

    Sapaev, U K; Babushkin, I; Herrmann, J


    We study a novel method of quasi-phase-matching for third harmonic generation in a gas cell using the periodic modulation of the gas pressure and thus of the third order nonlinear coefficient in the axial direction created by an ultrasound wave. Using a comprehensive numerical model we describe the quasi-phase matched third harmonic generation of UV (at 266 nm) and VUV pulses (at 133 nm) by using pump pulses at 800 nm and 400 nm, respectively, with pulse energy in the range from 3 mJ to 1 J. In addition, using chirped pump pulses, the generation of sub-20-fs VUV pulses without the necessity for an external chirp compensation is predicted.

  8. Non-atmospheric noble gases from CO(sub 2) well ga (United States)

    Caffee, M. W.; Hudson, G. B.; Velsko, C.; Alexander, E. C., Jr.; Huss, G. R.; Chivas, A. R.


    In recent years a number of studies of both terrestrial and extraterrestrial material has allowed the piecing together of a picture of events occurring in the early solar system (4.5 Gyr ago), including the formation of the earth. However, before this picture can be completed with an appropriate amount of detail it will be necessary to make further advances. One of the areas where knowledge is lacking is the chemical and isotopic composition of the earth as a whole. The lack of knowledge has less to do with the capabilities of modern techniques than with the availability of samples to study. About 99.6 percent of the earth's mass is contained in the mantle and core, leaving less that 1 percent in the crust and atmosphere. Although the crust is derived from the mantle it has undergone extensive changes and it is therefore difficult (although not impossible) to use crustal material to study events occurring 4.5 Gyr ago. More information about the early earth could be obtained from studies of the mantle but it is difficult to obtain mantle material, because the mean thickness of the crust is 17 km, much greater than even the deepest mines or drill shafts. The two types of available mantle samples are discussed.

  9. Generation of spectral clusters in a mixture of noble and Raman-active gases. (United States)

    Hosseini, Pooria; Abdolvand, Amir; St J Russell, Philip


    We report a novel scheme for the generation of dense clusters of Raman sidebands. The scheme uses a broadband-guiding hollow-core photonic crystal fiber (HC-PCF) filled with a mixture of H2, D2, and Xe for efficient interaction between the gas mixture and a green laser pump pulse (532 nm, 1 ns) of only 5 μJ of energy. This results in the generation from noise of more than 135 rovibrational Raman sidebands covering the visible spectral region with an average spacing of only 2.2 THz. Such a spectrally dense and compact fiber-based source is ideal for applications where closely spaced narrow-band laser lines with high spectral power density are required, such as in spectroscopy and sensing. When the HC-PCF is filled with a H2-D2 mixture, the Raman comb spans the spectral region from the deep UV (280 nm) to the near infrared (1000 nm).

  10. Strong suppression of the positronium channel in double ionization of noble gases by positron impact

    DEFF Research Database (Denmark)

    Bluhme, H.; Knudsen, H.; Merrison, J.P.


    Positron-induced double ionization of helium and neon has been studied at energies from threshold to 900 eV. A remarkable difference between the near-threshold behavior of the single and double ionization cross sections is found: Single ionization is dominated by positronium (Ps) formation, while...

  11. Trapping Planetary Noble Gases During the Fischer-Tropsch-Type Synthesis of Organic Materials (United States)

    Nuth, Joseph A.; Johnson, N. M.; Meshik, A.


    When hydrogen, nitrogen and CO arc exposed to amorphous iron silicate surfaces at temperatures between 500 - 900K, a carbonaceous coating forms via Fischer-Tropsch type reactions!, Under normal circumstances such a catalytic coating would impede or stop further reaction. However, we find that this coating is a better catalyst than the amorphous iron silicates that initiate these rcactions:u . The formation of a self-perpetuating catalytic coating on grain surfaces could explain the rich deposits of macromolecular carbon found in primitive meteorites and would imply that protostellar nebulae should be rich in organic materiaL Many more experiments are needed to understand this chemical system and its application to protostellar nebulae.

  12. DAVINCI: Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (United States)

    Glaze, Lori S.; Garvin, James B.; Robertson, Brent; Johnson, Natasha M.; Amato, Michael J.; Thompson, Jessica; Goodloe, Colby; Everette, Dave


    DAVINCI is one of five Discovery-class missions selected by NASA in October 2015 for Phase A studies. Launching in November 2021 and arriving at Venus in June of 2023, DAVINCI would be the first U.S. entry probe to target Venus atmosphere in 45 years. DAVINCI is designed to study the chemical and isotopic composition of a complete cross-section of Venus atmosphere at a level of detail that has not been possible on earlier missions and to image the surface at optical wavelengths and process-relevant scales.

  13. Generation of Spectral Clusters in a Mixture of Noble and Raman-Active Gases

    CERN Document Server

    Hosseini, Pooria; Russell, Philip St J


    We report a novel scheme for the generation of dense clusters of Raman sidebands. The scheme uses a broadband-guiding hollow-core photonic crystal fiber (HC-PCF) filled with a mixture of H2, D2, and Xe for efficient interaction between the gas mixture and a green laser pump pulse (532 nm, 1 ns) of only 5 uJ energy. This results in the generation from noise of more than 135 ro-vibrational Raman sidebands covering the visible spectral region with an average spacing of only 2 THz. Such a spectrally dense and compact fiber-based source is ideal for applications where closely spaced narrow-band laser lines with high spectral power density are required, such as in spectroscopy and sensing. When the HC-PCF is filled with a H2-D2 mixture the Raman comb spans the spectral region from the deep UV (280 nm) to the near infrared (1000 nm).

  14. Noble gas and carbon isotopes in Mariana Trough basalt glasses

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, M. [Centre de Recherches Petrographiques et Geochimiques, Centre National de la Recherche Scientifique, Rue Notre-Dame des Pauvres, BP 20, 54501 Vandoeuvre Cedex (France); Jambon, A. [Laboratoire de Magmatologie et Geochimie Inorganique et Experimentale, Universite Pierre et Marie Curie, F-75252 Paris Cedex 05 (France); Gamo, T. [Ocean Research Institute, The University of Tokyo, Nakano-ku Tokyo 164 (Japan); Nishio, Y. [Geological Institute, The University of Tokyo, Bunkyo-ku Tokyo 113 (Japan); Sano, Y. [Department of Earth and Planetary Sciences, Hiroshima University, Kagamiyama Higashi Hiroshima 739 (Japan)


    oble gas elemental and isotopic compositions have been measured as well as the abundance of C and its isotopic ratios in 11 glasses from submarine pillow basalts collected from the Mariana Trough. The {sup 3}He/{sup 4}He ratios of 8.22 and 8.51 R{sub atm} of samples dredged from the central Mariana Trough (similar18N) agree well with that of the Mid-Ocean Ridge Basalt (MORB) glasses (8.4{+-}0.3 R{sub atm}), whereas a mean ratio of 8.06{+-}0.35 R{sub atm} in samples from the northern Mariana Trough (similar20N) is slightly lower than those of MORB. One sample shows apparent excess of {sup 20}Ne and {sup 21}Ne relative to atmospheric Ne, suggesting incorporation of solar-type Ne in the magma source. There is a positive correlation between {sup 3}He/{sup 4}He and {sup 40}Ar/{sup 36}Ar ratios, which may be explained by mixing between MORB-type and atmospheric noble gases. Excess {sup 129}Xe is observed in the sample which also shows {sup 20}Ne and {sup 21}Ne excesses. Observed {delta}{sup 13}C values of similar20N samples vary from -3.76 per thousand to -2.80 per thousand, and appear higher than those of MORB, and the corresponding CO{sub 2}/{sup 3}He ratios are higher than those of MARA samples at similar18N, suggesting C contribution from the subducted slab. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  15. A model to estimate noble fir bough weight. (United States)

    Keith A. Blatner; Roger D. Fight; Nan Vance; Mark Savage; Roger. Chapman


    The harvesting of noble fir (Abies procera) for the production of Christmas wreaths and related products has been a mainstay of the nontimber forest products industry in the Pacific Northwest (PNW) for decades. Although noble fir is the single most important bough product harvested in the PNW, little or no work has been published concerning the...

  16. Deposition and characterization of noble metal onto surfaces of 304l stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Contreras R, A.; Arganis J, C. R.; Aguilar T, J. A.; Medina A, A. L., E-mail: aida.contreras@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)


    Noble metal chemical addition (NMCA) plus hydrogen water chemistry is an industry-wide accepted approach for potential intergranular stress corrosion cracking mitigation of BWR internals components. NMCA is a method of applying noble metal onto BWR internals surfaces using reactor water as the transport medium that causes the deposition of noble metal from the liquid onto surfaces. In this work different platinum concentration solutions were deposited onto pre-oxidized surfaces of 304l steel at 180 C during 48 hr in an autoclave. In order to simulate the zinc water conditions, deposits of Zn and Pt-Zn were also carried out. The solutions used to obtain the deposits were: sodium hexahydroxyplatinate (IV), zinc nitrate hydrate and zinc oxide. The deposits obtained were characterized by scanning electron microscopy and X-ray diffraction. Finally, the electrochemical corrosion potential of pre-oxidized samples with Pt deposit were obtained and compared with the electrochemical corrosion potential of only pre-oxidized samples. (Author)

  17. Remote Assessment of Gases (United States)


    PETROLEUM REFINERIES SUPERPHOSPHATE MANUFACTURE CHEMICAL FACTORIES UFg MANUFACTURE SI LICONE AND PLASTICS STEEL MILLS AND METAL FABRICATION...manufacture, enrichment , and reprocessing; gases evolved are, for example, SF-, UFg, HF, organic solvents such as ether, NO , Kr, Xe, I-, Br». c

  18. Strongly interacting Fermi gases

    Directory of Open Access Journals (Sweden)

    Bakr W.


    Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

  19. Potential energy curves for the interaction of Ag(5s) and Ag(5p) with noble gas atoms. (United States)

    Loreau, J; Sadeghpour, H R; Dalgarno, A


    We investigate the interaction of ground and excited states of a silver atom with noble gases (NG), including helium. Born-Oppenheimer potential energy curves are calculated with quantum chemistry methods and spin-orbit effects in the excited states are included by assuming a spin-orbit splitting independent of the internuclear distance. We compare our results with experimentally available spectroscopic data, as well as with previous calculations. Because of strong spin-orbit interactions, excited Ag-NG potential energy curves cannot be fitted to Morse-like potentials. We find that the labeling of the observed vibrational levels has to be shifted by one unit.

  20. Origins of geothermal gases at Yellowstone (United States)

    Lowenstern, Jacob B.; Bergfeld, Deborah; Evans, William C.; Hunt, Andrew G.


    Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant acid water. Gases in adjacent thermal areas often can be differentiated by isotopic and gas ratios, and cannot be tied to one another solely by shallow processes such as boiling-induced fractionation of a parent liquid. Instead, they inherit unique gas ratios (e.g., CH4/He) from the dominant rock reservoirs where they originate, some of which underlie the Quaternary volcanic rocks. Steam/gas ratios (essentially H2O/CO2) of Yellowstone fumaroles correlate with Ar/He and N2/CO2, strongly suggesting that H2O/CO2 is controlled by addition of steam boiled from water rich in atmospheric gases. Moreover, H2O/CO2 varies systematically with geographic location, such that boiling is more enhanced in some areas than others. The δ13C and 3He/CO2 of gases reflect a dominant mantle origin for CO2 in Yellowstone gas. The mantle signature is most evident at Mud Volcano, which hosts gases with the lowest H2O/CO2, lowest CH4 concentrations and highest He isotope ratios (~16Ra), consistent with either a young subsurface intrusion or less input of crustal and meteoric gas than any other location at Yellowstone. Across the YPVF, He isotope ratios (3He/4He) inversely vary with He concentrations, and reflect varied amounts of long- stored, radiogenic He added to the magmatic endmember within the crust. Similarly, addition of CH4 from organic-rich sediments is common in the eastern thermal areas at Yellowstone. Overall, Yellowstone gases reflect addition of deep, high-temperature magmatic gas (CO2-rich), lower-temperatures crustal gases (4He- and CH4-bearing), and those gases (N2, Ne, Ar) added

  1. Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts (United States)

    Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I.; Kuruba, Ramalinga; Damodaran, Krishnan; Jampani, Prashanth; Gattu, Bharat; Shanthi, Pavithra Murugavel; Damle, Sameer S.; Kumta, Prashant N.


    Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu1.5Mn1.5O4, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.

  2. Hyperpolarized noble gas magnetic resonance imaging of the animal lung: Approaches and applications (United States)

    Santyr, Giles E.; Lam, Wilfred W.; Parra-Robles, Juan M.; Taves, Timothy M.; Ouriadov, Alexei V.


    Hyperpolarized noble gas (HNG) magnetic resonance (MR) imaging is a very promising noninvasive tool for the investigation of animal models of lung disease, particularly to follow longitudinal changes in lung function and anatomy without the accumulated radiation dose associated with x rays. The two most common noble gases for this purpose are H3e (helium 3) and X129e (xenon 129), the latter providing a cost-effective approach for clinical applications. Hyperpolarization is typically achieved using spin-exchange optical pumping techniques resulting in ˜10 000-fold improvement in available magnetization compared to conventional Boltzmann polarizations. This substantial increase in polarization allows high spatial resolution (single-slice images of the lung to be obtained with excellent temporal resolution (lungs with 1 mm slice thickness can be obtained within reasonable breath-hold intervals (ventilation studies in animals. Special MR hardware and software considerations are described in order to use the strong but nonrecoverable magnetization as efficiently as possible and avoid depolarization primarily by molecular oxygen. Several applications of HNG MR imaging are presented, including measurement of gross lung anatomy (e.g., airway diameters), microscopic anatomy (e.g., apparent diffusion coefficient), and a variety of functional parameters including dynamic ventilation, alveolar oxygen partial pressure, and xenon diffusing capacity.

  3. Summary and Preliminary Interpretation of Tritium and Dissolved Noble Gas Data from Site 300

    Energy Technology Data Exchange (ETDEWEB)

    Visser, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Singleton, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Madrid, V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Esser, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    In October 2013, groundwater samples were collected from 10 wells from Site 300 and analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory (LLNL). Groundwater samples were analyzed for groundwater age tracers: tritium, the helium isotope ratio of dissolved helium and the concentrations of dissolved noble gases (Helium, Neon, Argon, Krypton, and Xenon). A subset of the samples was also analyzed for excess nitrogen due to saturated zone denitrification. The age-dating data were used to evaluate the degree to which groundwater at a particular monitoring well was derived from pre-modern and/or modern sources. More specifically, the analyses can be used to determine whether the recharge age of the groundwater beneath the site pre-dates anthropogenic activities at the site.

  4. The end of a noble narrative?

    DEFF Research Database (Denmark)

    Manners, Ian James; Murray, Philomena


    The award of the Nobel Peace Prize 2012 to the European Union (EU) came as a surprise. Not only was the Eurozone economic crisis undermining both policy effectiveness and public support for the EU, but it was also seriously challenging the EU’s image in global politics. Although the Nobel Committee...... acknowledged these grave difficulties and the current considerable unrest in Europe, it wished to focus attention on what it regarded as the EU’s most important achievement: helping to ‘transform most of Europe from a continent of war to a continent of peace’. However, some six decades after the creation...... of the forerunner to the current EU we ask if this noble narrative of war and peace, which is at the heart of European integration, at an end. We argue that this principled account is likely to remain just one of several narratives of European integration, but with its reputation somewhat tarnished. Fresh...

  5. Noble metal surface degradation induced by organothiols (United States)

    de Poel, Wester; Gasseling, Anouk; Mulder, Peter; Steeghs, Antoon P. G.; Elemans, Johannes A. A. W.; van Enckevort, Willem J. P.; Rowan, Alan E.; Vlieg, Elias


    Copper, silver and gold layers evaporated on the muscovite mica (001) surface were exposed to a series of molecules containing an organothiol and/or a carboxylic acid chemical functional group to investigate the potential of these compounds to modify the surfaces. The surfaces were investigated using optical microscopy, atomic force microscopy, scanning electron microscopy, energy dispersive analysis of X-rays, and X-ray diffraction. Organothiols containing a carboxylic acid group were found to change the surface morphology drastically over a period of days, while molecules containing only one of these functional groups were usually not able to do so. The mechanism is most likely a reaction between the organothiol and the metal surface, forming a thermodynamically stable new compound. This finding could be of importance in the many applications where organothiols are used to functionalize noble metal surfaces.

  6. Sudden releases of gases

    Directory of Open Access Journals (Sweden)

    Chaloupecká Hana


    Full Text Available Conurbations all over the world have enlarged for numberless years. The accidental or intentional releases of gases become more frequent. Therefore, these crises situations have to be studied. The aim of this paper is to describe experiments examining these processes that were carried out in the laboratory of Environmental Aerodynamics of the Institute of Thermomechanics AS CR in Nový Knín. Results show huge puff variability from replica to replica.

  7. Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow (United States)

    Okazaki, Ryuji; Noguchi, Takaaki; Tsujimoto, Shin-ichi; Tobimatsu, Yu; Nakamura, Tomoki; Ebihara, Mitsuru; Itoh, Shoichi; Nagahara, Hiroko; Tachibana, Shogo; Terada, Kentaro; Yabuta, Hikaru


    We have investigated seven micrometeorites (MMs) from Antarctic snow collected in 2003 and 2010 by means of electron microscopy, X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy (TEM) observation, and noble-gas isotope analysis. Isotopic ratios of He and Ne indicate that the noble gases in these MMs are mostly of solar wind (SW). Based on the release patterns of SW 4He, which should reflect the degree of heating during atmospheric entry, the seven MMs were classified into three types including two least heated, three moderately heated, and two severely heated MMs. The heating degrees are well correlated to their mineralogical features determined by TEM observation. One of the least heated MMs is composed of phyllosilicates, whereas the other consists of anhydrous minerals within which solar flare tracks were observed. The two severely heated MMs show clear evidence of atmospheric heating such as partial melt of the uppermost surface layer in one and abundant patches of dendritic magnetite and Si-rich glass within an olivine grain in the other. It is noteworthy that a moderately heated MM composed of a single crystal of olivine has a 3He/4He ratio of 8.44 × 10-4, which is higher than the SW value of 4.64 × 10-4, but does not show a cosmogenic 21Ne signature such as 20Ne/21Ne/22Ne = 12.83/0.0284/1. The isotopic compositions of He and Ne in this sample cannot be explained by mixing of a galactic cosmic ray (GCR)-produced component and SW gases. The high 3He/4He ratio without cosmogenic 21Ne signature likely indicates the presence of a 3He-enriched component derived from solar energetic particles.


    Busey, H.M.


    A convection type recombiner is described for catalytically recombining hydrogen and oxygen which have been radiolytically decomposed in an aqueous homogeneous nuclear reactor. The device is so designed that the energy of recombination is used to circulate the gas mixture over the catalyst. The device consists of a vertical cylinder having baffles at its lower enda above these coarse screens having platinum and alumina pellets cemented thereon, and an annular passage for the return of recombined, condensed water to the reactor moderator system. This devicea having no moving parts, provides a simple and efficient means of removing the danger of accumulated hot radioactive, explosive gases, and restoring them to the moderator system for reuse.

  9. Properties of Copper Cavities Coated with Niobium Using Different Discharge Gases

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Marino, M; Peck, M A; Russo, R; Valente, A M


    Experimental evidence is presented showing that in conformity with theoretical expectations, discharge gas atoms are trapped in sputtered films whenever a gas of atomic mass smaller than that of the c athode is used. In such a case, discharge gas atoms may be reflected by the cathode as high energy neutrals and get incorporated in the growing film. Niobium films have been produced using Ne, Ar, Kr, Xe and then analysed for rare gas content by thermal extraction. The gas concentrations are found to vary from the several percent range for Ne down to the ppm level for Kr and Xe. The noble gas conce ntration in the film influences the RRR and, in the case of high concentration, also the critical temperature. To study the effect of the implanted noble gas on the superconducting RF parameters, seve ral 1.5 GHz copper cavities have been niobium-coated using the different discharge gases. The noble gases trapped in the film affect the penetration depth, the temperature dependent losses (RBCS), the losses induced by t...

  10. Noble metal abundances in an early Archean impact deposit (United States)

    Kyte, Frank T.; Zhou, Lei; Lowe, Donald R.


    Detailed analyses are reported on the concentrations of the noble metals Pd, Os, Ir, Pt, and Au in an early Archean spherule bed (S4) of probably impact origin from the lower Fig Tree Group, Barberton Greenstone Belt, South Africa. Compared to other sedimentary deposits of known or suspected impact origin, some noble metals are present in exceptionally high concentrations. Noble metal abundances are fractionated relative to abundances in chondrites with ratios of Os/Ir, Pt/Ir, Pd/Ir, and Au/Ir at only 80, 80, 41, and 2 percent of these values on CI chondrites. Although an extraterrestrial source is favored for the noble metal enrichment, the most plausible cause of the fractionation is by regional hydrothermal/metasomatic alteration.

  11. Microleakage and marginal gap of adhesive cements for noble alloy full cast crowns. (United States)

    Hooshmand, T; Mohajerfar, M; Keshvad, A; Motahhary, P


    Very limited comparative information about the microleakage in noble alloy full cast crowns luted with different types of adhesive resin cements is available. The purpose of this study was to evaluate the microleakage and marginal gap of two self-adhesive resin cements with that of other types of adhesive luting cements for noble alloy full cast crowns. Fifty noncarious human premolars and molars were prepared in a standardized manner for full cast crown restorations. Crowns were made from a noble alloy using a standardized technique and randomly cemented with five cementing agents as follows: 1) GC Fuji Plus resin-modified glass ionomer cement, 2) Panavia F 2.0 resin cement, 3) Multilink Sprint self-adhesive resin cement, 4), Rely X Unicem self-adhesive resin cement with pretreatment, and 5) Rely X Unicem with no pretreatment. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution, vertically cut in a mesiodistal direction and evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a nonparametric Kruskal-Wallis test followed by Dunn multiple range test at a pcrown interfaces. The greatest amount of microleakage was found for Panavia F 2.0 resin cement followed by GC Fuji Plus at both interfaces. No statistically significant difference in the marginal gap values was found between the cementing agents evaluated (p>0.05). The self-adhesive resin cements provided a much better marginal seal for the noble alloy full cast crowns compared with the resin-modified glass ionomer or dual-cured resin-based cements.

  12. High Voltage in Noble Liquids for High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rebel, B. [Fermilab; Bernard, E. [Yale U.; Faham, C. H. [LBL, Berkeley; Ito, T. M. [Los Alamos; Lundberg, B. [Maryland U.; Messina, M. [Columbia U.; Monrabal, F. [Valencia U., IFIC; Pereverzev, S. P. [LLNL, Livermore; Resnati, F. [Zurich, ETH; Rowson, P. C. [SLAC; Soderberg, M. [Fermilab; Strauss, T. [Bern U.; Tomas, A. [Imperial Coll., London; Va' vra, J. [SLAC; Wang, H. [UCLA


    A workshop was held at Fermilab November 8-9, 2013 to discuss the challenges of using high voltage in noble liquids. The participants spanned the fields of neutrino, dark matter, and electric dipole moment physics. All presentations at the workshop were made in plenary sessions. This document summarizes the experiences and lessons learned from experiments in these fields at developing high voltage systems in noble liquids.

  13. On Classical Ideal Gases

    Directory of Open Access Journals (Sweden)

    Laurent Chusseau


    Full Text Available We show that the thermodynamics of ideal gases may be derived solely from the Democritean concept of corpuscles moving in vacuum plus a principle of simplicity, namely that these laws are independent of the laws of motion, aside from the law of energy conservation. Only a single corpuscle in contact with a heat bath submitted to a z and t-invariant force is considered. Most of the end results are known but the method appears to be novel. The mathematics being elementary, the present paper should facilitate the understanding of the ideal gas law and of classical thermodynamics even though not-usually-taught concepts are being introduced.

  14. Noble Metal-Membrane Composites for Electrochemical Applications (United States)

    Millet, Pierre


    Composite materials are a new class of materials that combine two or more separate components into a form suitable for structural applications. While each component retains its identity, the new composite material displays macroscopic properties superior to its parent constituents, particularly in terms of mechanical properties and economic value. Perhaps best known for their use in aerospace applications, advanced composites are also used by the automotive, biomedical, and sporting goods markets. In addition, these strong, stiff, lightweight materials are seeing increased use in the rehabilitation, repair, and retrofit of civil infrastructure, including, for example, as replacement bridge decks and wrapping for concrete columns. New composite materials presenting some interesting features which are not directly related to their mechanical properties are appearing. This is the case of noble metal-based polymeric composites, the preparation and characterization of which are considered in this article with regard to their electrochemical properties. These composites are of great practical interest because of potential applications in water electrolysis and H2-O2 fuel cells. Electrolyzers and fuel cells can be used for terrestrial transportation, oxygen generation in submarines, and energy conversion in spacecraft.

  15. Noble Gas Measurement and Analysis Technique for Monitoring Reprocessing Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Charlton, William S [Univ. of California, Berkeley, CA (United States)


    An environmental monitoring technique using analysis of stable noble gas isotopic ratios on-stack at a reprocessing facility was developed. This technique integrates existing technologies to strengthen safeguards at reprocessing facilities. The isotopic ratios are measured using a mass spectrometry system and are compared to a database of calculated isotopic ratios using a Bayesian data analysis method to determine specific fuel parameters (e.g., burnup, fuel type, fuel age, etc.). These inferred parameters can be used by investigators to verify operator declarations. A user-friendly software application (named NOVA) was developed for the application of this technique. NOVA included a Visual Basic user interface coupling a Bayesian data analysis procedure to a reactor physics database (calculated using the Monteburns 3.01 code system). The integrated system (mass spectrometry, reactor modeling, and data analysis) was validated using on-stack measurements during the reprocessing of target fuel from a U.S. production reactor and gas samples from the processing of EBR-II fast breeder reactor driver fuel. These measurements led to an inferred burnup that matched the declared burnup with sufficient accuracy and consistency for most safeguards applications. The NOVA code was also tested using numerous light water reactor measurements from the literature. NOVA was capable of accurately determining spent fuel type, burnup, and fuel age for these experimental results. Work should continue to demonstrate the robustness of this system for production, power, and research reactor fuels.

  16. Methodology to determine the efficiency of a beta emitter gases monitor; Metodologia para determinacao da eficiencia de um monitor de gases emissores de particulas beta

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Marcos Rodrigues de


    This work presents a methodology developed to determinate the efficiency of air monitors used to measure the concentration of beta emitters noble gases in nuclear power stations. Efficiency values, obtained by means of theoretical computation are compared with experimental values. The experimental part of the work was performed using three different point beta source, to simulate small amounts of gas uniformly distributed in small volume. The comparison shows that theoretical an experimental values agree within 4,2 % for {sup 90}Sr + {sup 90}Y, {sup 204}Tl and {sup 45}Ca beta sources. (author)

  17. Optical response of noble metal alloy nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, Amit, E-mail:; Verma, S.S.


    The optical response, stability, and cost-effectiveness of individual noble metals can be improved by combining them to form alloy nanostructures. The present work reveals the influence of shape, size, and metal type on the optical response of alloy nanoparticles using discrete dipole approximation (DDA) simulations. It is found that sharp corner nanostructures show enhanced plasmonic properties in comparison to rounded counterpart. For all the three shapes, viz., nanocubes, rectangular, and nanobar particles, the increase in length resulted in redshifts of the longitudinal plasmon resonance alongwith enhancement in the scattering yield as well as relative efficiency parameters except for nanocubes of edge length 120 nm. The effect of size on full width at half maxima (FWHM) has also been studied and found to be maximal for nanocubes in comparison to other nanostructures. - Highlights: • The optical response of alloy nanostructures has been studied by discrete dipole approximation. • Sharp corner nanostructures show enhanced plasmonic properties. • Nanobars may be preferred over other nanostructures for absorption-based plasmonic applications. • Nanocubes of edge length greater than 100 nm may be useful for plasmonic solar cells. • Rectangular and nanobar particles may be preferred over nanocubes in plasmon sensing.

  18. A noble metal-free proton-exchange membrane fuel cell based on bio-inspired molecular catalysts. (United States)

    Tran, P D; Morozan, A; Archambault, S; Heidkamp, J; Chenevier, P; Dau, H; Fontecave, M; Martinent, A; Jousselme, B; Artero, V


    Hydrogen is a promising energy vector for storing renewable energies: obtained from water-splitting, in electrolysers or photoelectrochemical cells, it can be turned back to electricity on demand in fuel cells (FCs). Proton exchange membrane (PEM) devices with low internal resistance, high compactness and stability are an attractive technology optimized over decades, affording fast start-up times and low operating temperatures. However, they rely on the powerful catalytic properties of noble metals such as platinum, while lower cost, more abundant materials would be needed for economic viability. Replacing these noble metals at both electrodes has long proven to be a difficult task, so far incompatible with PEM technologies. Here we take advantage of newly developed bio-inspired molecular H 2 oxidation catalysts and noble metal-free O 2 -reducing materials, to fabricate a noble metal-free PEMFC, with an 0.74 V open circuit voltage and a 23 μW cm -2 output power under technologically relevant conditions. X-ray absorption spectroscopy measurements confirm that the catalysts are stable and retain their structure during turnover.

  19. Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water-Xe system. (United States)

    Artyukhov, Vasilii I; Pulver, Alexander Yu; Peregudov, Alex; Artyuhov, Igor


    Motivated by recent experiments showing the promise of noble gases as cryoprotectants, we perform molecular dynamics modeling of phase transitions in water with xenon under cooling. We follow the structure and dynamics of xenon water solution as a function of temperature. Homogeneous nucleation of clathrate hydrate phase is observed and characterized. As the temperature is further reduced we observe hints of dissociation of clathrate due to stronger hydrophobic hydration, pointing towards a possible instability of clathrate at cryogenic temperatures and conversion to an amorphous phase comprised of "xenon + hydration shell" Xe·(H2O)21.5 clusters. Simulations of ice-xenon solution interface in equilibrium and during ice growth reveal the effects of xenon on the ice-liquid interface, where adsorbed xenon causes roughening of ice surface but does not preferentially form clathrate. These results provide evidence against the ice-blocker mechanism of xenon cryoprotection.

  20. Phase equilibria at low temperature for light hydrocarbons-methanol-water-acid gases mixtures: measurements and modelling; Equilibres de phases a basse temperature de systemes complexes CO{sub 2} - hydrocarbures legers - methanol - eau: mesures et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ruffine, L.


    The need to develop and improve natural gas treatment processes is real. The petroleum industry usually uses separation processes which require phase equilibrium phenomena. Yet, the complexity of the phase equilibria involved results in a lack of data, which in turn limits the development of thermodynamic models. The first part of this work is devoted to experimental investigations for systems containing light hydrocarbons, methanol, water and acid gases. We present a new apparatus that was developed to measure vapor-liquid and vapor-liquid-liquid equilibria. It allowed us to obtain new phase composition data for the methanol-ethane binary system and different mixtures, and also to determine a part of the three phases equilibrium envelope of the same systems. In the second part of this work, we have developed a thermodynamic model based on the CPA equation of state. This choice may be justified by the presence of associating components like methanol, hydrogen sulfide and water in the systems. Such model is necessary for the design of gas treatment plants. Our model provides good results for phase equilibrium calculations for binaries systems without binary interaction parameter in many cases, and describes correctly the vapour-liquid and vapor-liquid-liquid equilibria for complex mixtures. (author)

  1. Characterization of gas chemistry and noble-gas isotope ratios of inclusion fluids in magmatic-hydrothermal and magmatic-steam alunite (United States)

    Landis, G.P.; Rye, R.O.


    Chemical and isotope data were obtained for the active gas and noble gas of inclusion fluids in coarse-grained samples of magmatic-hydrothermal and magmatic-steam alunite from well-studied deposits (Marysvale, Utah; Tambo, Chile; Tapajo??s, Brazil; Cactus, California; Pierina, Peru), most of which are discussed in this Volume. Primary fluid inclusions in the alunite typically are less than 0.2 ??m but range up to several micrometers. Analyses of the active-gas composition of these alunite-hosted inclusion fluids released in vacuo by both crushing and heating indicate consistent differences in the compositions of magmatic-hydrothermal and magmatic-steam fluids. The compositions of fluids released by crushing were influenced by contributions from significant populations of secondary inclusions that trapped largely postdepositional hydrothermal fluids. Thermally released fluids gave the best representation of the fluids that formed primary alunite. The data are consistent with current models for the evolution of magmatic-hydrothermal and magmatic-steam fluids. Magmatic-steam fluids are vapor-dominant, average about 49 mol% H2O, and contain N2, H2, CH4, CO, Ar, He, HF, and HCl, with SO2 the dominant sulfur gas (average SO2/ H2S=202). In contrast, magmatic-hydrothermal fluids are liquid-dominant, average about 88 mol% H2O, and N2, H2, CO2, and HF, with H2S about as abundant as SO2 (average SO2/H2 S=0.7). The low SO2/H2S and N2/Ar ratios, and the near-absence of He in magmatic-hydrothermal fluids, are consistent with their derivation from degassed condensed magmatic fluids whose evolution from reduced-to-oxidized aqueous sulfur species was governed first by rock and then by fluid buffers. The high SO2/H2S and N2/Ar with significant concentrations of He in magmatic-steam fluids are consistent with derivation directly from a magma. None of the data supports the entrainment of atmospheric gases or mixing of air-saturated gases in meteoric water in either magmatic

  2. Steady state fractionation of heavy noble gas isotopes in a deep unsaturated zone (United States)

    Seltzer, Alan M.; Severinghaus, Jeffrey P.; Andraski, Brian J.; Stonestrom, David A.


    To explore steady state fractionation processes in the unsaturated zone (UZ), we measured argon, krypton, and xenon isotope ratios throughout a ∼110 m deep UZ at the United States Geological Survey (USGS) Amargosa Desert Research Site (ADRS) in Nevada, USA. Prior work has suggested that gravitational settling should create a nearly linear increase in heavy-to-light isotope ratios toward the bottom of stagnant air columns in porous media. Our high-precision measurements revealed a binary mixture between (1) expected steady state isotopic compositions and (2) unfractionated atmospheric air. We hypothesize that the presence of an unsealed pipe connecting the surface to the water table allowed for direct inflow of surface air in response to extensive UZ gas sampling prior to our first (2015) measurements. Observed isotopic resettling in deep UZ samples collected a year later, after sealing the pipe, supports this interpretation. Data and modeling each suggest that the strong influence of gravitational settling and weaker influences of thermal diffusion and fluxes of CO2 and water vapor accurately describe steady state isotopic fractionation of argon, krypton, and xenon within the UZ. The data confirm that heavy noble gas isotopes are sensitive indicators of UZ depth. Based on this finding, we outline a potential inverse approach to quantify past water table depths from noble gas isotope measurements in paleogroundwater, after accounting for fractionation during dissolution of UZ air and bubbles.

  3. Steady state fractionation of heavy noble gas isotopes in a deep unsaturated zone (United States)

    Seltzer, Alan M.; Severinghaus, Jeffrey P.; Andraski, Brian J.; Stonestrom, David A.


    To explore steady state fractionation processes in the unsaturated zone (UZ), we measured argon, krypton, and xenon isotope ratios throughout a ˜110 m deep UZ at the United States Geological Survey (USGS) Amargosa Desert Research Site (ADRS) in Nevada, USA. Prior work has suggested that gravitational settling should create a nearly linear increase in heavy-to-light isotope ratios toward the bottom of stagnant air columns in porous media. Our high-precision measurements revealed a binary mixture between (1) expected steady state isotopic compositions and (2) unfractionated atmospheric air. We hypothesize that the presence of an unsealed pipe connecting the surface to the water table allowed for direct inflow of surface air in response to extensive UZ gas sampling prior to our first (2015) measurements. Observed isotopic resettling in deep UZ samples collected a year later, after sealing the pipe, supports this interpretation. Data and modeling each suggest that the strong influence of gravitational settling and weaker influences of thermal diffusion and fluxes of CO2 and water vapor accurately describe steady state isotopic fractionation of argon, krypton, and xenon within the UZ. The data confirm that heavy noble gas isotopes are sensitive indicators of UZ depth. Based on this finding, we outline a potential inverse approach to quantify past water table depths from noble gas isotope measurements in paleogroundwater, after accounting for fractionation during dissolution of UZ air and bubbles.

  4. International Conference on LIght Detection in Noble Elements

    CERN Document Server


    The objective of the Light Detection in Noble Elements (LIDINE) 2015 conference is to promote discussion between the members of the particle and nuclear physics communities about light and charge collection in detectors based on liquid or gaseous noble elements, xenon and argon being the most common, but neon and helium also in use, and represented at this conference. The neutrino physics, ultra-cold neutron study, dark matter search, and medical physics communities all utilize noble-based detector technologies, recording UV scintillation and/or ionization. Therefore, this will be an interdisciplinary opportunity for information exchange, and a chance for each of these communities enumerated above, in the U.S. as well as abroad, to expand their technical knowledge bases.

  5. Petrographic shock indicators and noble gas signatures in a H and an L chondrite from Antarctica (United States)

    Ranjith, P. M.; He, Huaiyu; Miao, Bingkui; Su, Fei; Zhang, Chuantong; Xia, Zhipeng; Xie, Lanfang; Zhu, Rixiang


    Petrographic shock indicators and noble gas signatures are studied in two ordinary chondrites, Grove Mountain (GRV) 13083 (H4) and GRV 13095 (L5), from Antarctica to investigate the degree of shock metamorphism and impact related chronologies on H and L chondrite parent bodies. In the study, we have combined both noble gas signatures and petrographic observations to understand impact effects. Based on the impact features in silicates and metal-troilite assemblages, the shock stages of the samples are classified as S6 and S5 for GRV 13095 (L5) and GRV 13083 (H4) respectively. The nominal K-Ar gas retention age of GRV 13095 (L5, S6) using bulk sample is estimated as 459 ± 13 Ma, supporting the recent major catastrophic break up event at 470 Ma on the L-chondrite parent body. The cosmic ray exposure age based on He, Ne and Ar noble gas measurements is estimated as 14.1 ± 2.5 Ma. The radiogenic gas contents in GRV 13095 (avg. 4He = 61.5 × 10-8 ccSTP/g and avg. 40Ar = 173.5 × 10-8 ccSTP/g) are observed as depleted. The depletion in radiogenic gases is consistent with the severe shock metamorphism in GRV 13095 as indicated by olivine-ringwoodite transformation in it. The estimated nominal K-Ar age of 3.67 ± 0.26 Ga for GRV 13083 shows that it falls in the major impact age distribution between 3.5 and 4.0 Ga among H-chondrites. The cosmic ray exposure age of GRV 13083 is 3.9 ± 0.7 Ma, which is younger than the major peak in the exposure age distribution for H-chondrites. The He gas retention ages in both samples are found to be younger/lower than their respective nominal K-Ar ages, which could be due to partial loss of radiogenic He. Trapped gas loss along with radiogenic gas losses in both samples, are the adverse effects of shock metamorphism.

  6. Process for Making a Noble Metal on Tin Oxide Catalyst (United States)

    Davis, Patricia; Miller, Irvin; Upchurch, Billy


    To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

  7. Noble Metal/Ceramic Composites in Flame Processes

    DEFF Research Database (Denmark)

    Schultz, Heiko; Madler, Lutz; Strobel, Reto

    size is mainly dependent on its loading [3,7]. In this study, the role of the supporting metal oxide on the noble metal particle size was systematically investigated for the flame spray pyrolysis process. The materials were produced at fixed process conditions such as resident time of the particles...... in the flame, energy input, maximum temperature and cooling rate. Having the same surface area of the support and metal loading, the materials exhibited different noble metal particle sizes. A fundamental understanding of the mechanisms of metal particle formation in the flame and the effect of the metal oxide...

  8. Optical and structural properties of noble-metal nanoparticles; Optische und strukturelle Eigenschaften von Edelmetallnanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Dahmen, C.


    Noble-metal nanoparticles exhibit rich optical behavior, such as resonant light scattering and absorption and non-linear signal enhancement. This makes them attractive for a multitude of physical, chemical, and biophysical applications. For instance, recent biomedical experiments demonstrate the suitability of noble-metal nanoparticles for selective photothermal apoptosis by heat transport by laser irradiation. The applications of nanoparticles largely exploit that plasmons, i. e. collective oscillations of the conduction electrons, can be optically excited in these nanoparticles. In optical spectroscopy, these are seen as pronounced resonances. In the first part of this work, model calculations are employed to elucidate how radiation damping in noble-metal nanoparticles, i. e. the transformation of plasmons into photons, depends on particle size, particle shape, and on electromagnetic coupling between individual particles. Exact electrodynamic calculations are carried out for individual spheroidal particles and for pairs of spherical particles. These calculations for spheroidal particles demonstrate for the first time that radiative plasmon decay is determined by both the particle volume and the particle shape. Model calculations for pairs of large spherical particles reveal that the electromagnetic fields radiated by the particles mediate electromagnetic coupling at interparticle distances in the micrometer range. This coupling can lead to immense modulations of the plasmonic linewidth. The question whether this coupling is sufficiently strong to mediate extended, propagating, plasmon modes in nanoparticle arrays is addressed next. Detailed analysis reveals that this is not the case; instead, for the particle spacings regarded here, a non-resonant, purely diffractive coupling is observed, which is identified by steplike signatures in reflection spectra of the particle arrays. In the second part of this work, structural and optical properties of noble

  9. Field Enhancement using Noble Metal Structures (United States)

    Liu, Benliang

    Resonance may be one of the most fundamental rules of nature. Electromagnetic resonance at nanometer scale could produce a giant field enhancement at optical frequency, providing a way to measure and control the process of atoms and molecules at single molecule scale. For example, the giant field enhancement would provide single molecule sensitivity for Raman scattering, which provides unique tools in measuring the quantity in extremely low concentration. In addition, light-emitting diodes could have high brightness but low input power that would be revolutionary in the optoelectronic industry. Although light enhancement is promising in several key technology areas, there are several challenges remain to be tackled. In particular, since the field enhancement is so strongly geometry dependent that slight modification of the geometry can lead to large variations in the outcome, a thorough understanding in how the geometry of the structure affects the field enhancement and creating proper methods to fabricate these structures reproducibly is of most importance. This thesis is devoted to design, fabrication and characterization of field enhancement generated on the surface of noble metals such as silver or gold with 1D structure. The s-polarized field enhancement arising from one-dimensional metal gratings is designed and optimized by using Rigorous Coupling Wave Analysis (RCWA). After optimization, the strongest enhancement factor is found to be 9.7 for 514nm wavelength light. The theoretical results arc confirmed by angle-dependent reflectivity measurements and the experimental results are found to support the theory. A novel single slit structure employing surface plasmon polaritons (SPPs) for enhancing the electric field is studied. SPPs are first generated on a 50 nm thick metal film using attenuated total reflection coupling, and they are subsequently coupled to the cavity mode induced by the single slit. As a result, the field enhancement is found at least 3


    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R


    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  11. Inculcating Noble Values for Pre-Service Teachers (United States)

    Hasan, Anita Abu; Hamzah, Mohd Isa; Awang, Mohd Mahzan


    This study aims to identify the noble values that are being cultivated and practiced in the process of teaching and learning of Ethnic Relations Course for pre-service teachers. Element values investigated including the identity, loyalty, patriotism, tolerance, cooperation and pride as a Malaysian. This quantitative research employs a survey…

  12. Noble-Metal Nanocrystals with Controlled Facets for Electrocatalysis. (United States)

    Hong, Jong Wook; Kim, Yena; Kwon, Yongmin; Han, Sang Woo


    Noble-metal nanocrystals (NCs) show excellent catalytic performance for many important electrocatalysis reactions. The crystallographic properties of the facets by which the NCs are bound, closely associated with the shape of the NCs, have a profound influence on the electrocatalytic function of the NCs. To develop an efficient strategy for the synthesis of NCs with controlled facets as well as compositions, understanding of the growth mechanism of the NCs and their interaction with the chemical species involved in NC synthesis is quite important. Furthermore, understanding the facet-dependent catalytic properties of noble-metal NCs and the corresponding mechanisms for various electrocatalysis reactions will allow for the rational design of robust electrocatalysts. In this review, we summarize recently developed synthesis strategies for the preparation of mono- and bimetallic noble-metal NCs by classifying them by the type of facets through which they are enclosed and discuss the electrocatalytic applications of noble-metal NCs with controlled facets, especially for reactions associated with fuel-cell applications, such as the oxygen reduction reaction and fuel (methanol, ethanol, and formic acid) oxidation reactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Chemical reactivity of the compressed noble gas atoms and their ...

    Indian Academy of Sciences (India)

    Attempts are made to gain insights into the effect of confinement of noble gas atoms on their various reactivity indices. Systems become harder, less polarizable and difficult to excite as the compression increases. Ionization also causes similar effects. A quantum fluid density functional technique is adopted in order to study ...

  14. Non-noble metal based catalysts for aqueous phase processing

    NARCIS (Netherlands)

    van Haasterecht, T.|info:eu-repo/dai/nl/328206458


    This thesis concerns the evaluation of the potential of supported non-noble metal catalysts in aqueous phase processes for the production hydrogen and oxygenates. The aim of this thesis is to investigate how different factors, especially the nature of the metal, additives and reaction conditions,

  15. Nanocrystalline Metal Oxides for Methane Sensors: Role of Noble Metals

    Directory of Open Access Journals (Sweden)

    S. Basu


    Full Text Available Methane is an important gas for domestic and industrial applications and its source is mainly coalmines. Since methane is extremely inflammable in the coalmine atmosphere, it is essential to develop a reliable and relatively inexpensive chemical gas sensor to detect this inflammable gas below its explosion amount in air. The metal oxides have been proved to be potential materials for the development of commercial gas sensors. The functional properties of the metal oxide-based gas sensors can be improved not only by tailoring the crystal size of metal oxides but also by incorporating the noble metal catalyst on nanocrystalline metal oxide matrix. It was observed that the surface modification of nanocrystalline metal oxide thin films by noble metal sensitizers and the use of a noble metal catalytic contact as electrode reduce the operating temperatures appreciably and improve the sensing properties. This review article concentrates on the nanocrystalline metal oxide methane sensors and the role of noble metals on the sensing properties.

  16. Strategic role of selected noble metal nanoparticles in medicine. (United States)

    Rai, Mahendra; Ingle, Avinash P; Birla, Sonal; Yadav, Alka; Santos, Carolina Alves Dos


    Noble metals and their compounds have been used as therapeutic agents from the ancient time in medicine for the treatment of various infections. Recently, much progress has been made in the field of nanobiotechnology towards the development of different kinds of nanomaterials with a wide range of applications. Among the metal nanoparticles, noble metal nanoparticles have demonstrated potential biomedical applications. Due to the small size, nanoparticles can easily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. Noble metal nanoparticles inspired the researchers due to their remarkable role in detection and treatment of dreadful diseases. In this review, we have attempted to focus on the biomedical applications of noble metal nanoparticles particularly, silver, gold, and platinum in diagnosis and treatment of dreaded diseases such as cancer, human immunodeficiency virus (HIV), tuberculosis (TB), and Parkinson disease. In addition, the role of silver nanoparticles (AgNPs) such as novel antimicrobials, gold nanoparticles (AuNPs) such as efficient drug carrier, uses of platinum nanoparticles (PtNPs) in bone allograft, dentistry, etc. have been critically reviewed. Moreover, the toxicity due to the use of metal nanoparticles and some unsolved challenges in the field have been discussed with their possible solutions.

  17. Hydrodynamics of unitary Fermi gases (United States)

    Young, Ryan E.

    Unitary fermi gases have been widely studied as they provide a tabletop archetype for re- search on strongly coupled many body systems and perfect fluids. Research into unitary fermi gases can provide insight into may other strongly interacting systems including high temperature superconductor, quark-gluon plasmas, and neutron stars. Within the unitary regime, the equilib- rium transport coefficients and thermodynamic properties are universal functions of density and temperature. Thus, unitary fermi gases provide a archetype to study nonperturbative many-body physics, which is of fundamental significance and crosses several fields. This thesis reports on two topics regarding unitary fermi gases. A recent string theory conjecture gives a lower bound for the dimensionless ratio of shear viscosity of entropy, η/s ≥ 4pi /kb . Unitary fermi gases are a candidate for prefect fluids, yet η/s is well above the string theory bound. Using a stochastic formulation of hydrodynamics, we calculate a lower bound for this ratio accounting for the momentum dissipation from fluctuations. This lower bound is in good agreement with both theoretical and experimental results. The second question addressed is the simulation of elliptic flow. Elliptic flow, first observed in 2002, is a characteristic of strongly coupled systems and has been studied in both quark-gluon plasmas and unitary fermi gases. As such, simulations of these systems are of interest. We test a variety of lattice Boltzmann models and compare the simulation results to the theoretical and experimental findings.

  18. Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Rudolf Herrmann


    Full Text Available The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core–shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4–260 ± 40 nm diameter can be prepared and decorated with noble metal nanoparticles (2–5 nm diameter. Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation.

  19. Solubility of gases and solvents in silicon polymers: molecular simulation and equation of state modeling

    DEFF Research Database (Denmark)

    Economou, Ioannis; Makrodimitri, Zoi A.; Kontogeorgis, Georgios


    The solubility of n-alkanes, perfluoroalkanes, noble gases and light gases in four elastomer polymers containing silicon is examined based on molecular simulation and macroscopic equation of state modelling. Polymer melt samples generated from molecular dynamics ( MD) are used for the calculation...... of gas and solvent solubilities using the test particle insertion method of Widom. Polymer chains are modelled using recently developed realistic atomistic force fields. Calculations are performed at various temperatures and ambient pressure. A crossover in the temperature dependence of solubility...... as a function of the gas/solvent critical temperature is observed for all polymers. A macroscopic model based on the simplified perturbed chain-statistical associating fluid theory ( sPC-SAFT) is used for the prediction and correlation of solubilities in poly( dimethylsilamethylene) and poly( dimethylsiloxane...

  20. Post-irradiation analysis of an ISOLDE lead-bismuth target: Stable and long-lived noble gas nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Leya, I., E-mail: [University of Bern, Space Science and Planetology, Bern (Switzerland); Grimberg, A. [University of Bern, Space Science and Planetology, Bern (Switzerland); Isotope Geochemistry, ETH Zürich, Zürich (Switzerland); David, J.-C. [CEA/Saclay, Irfu/SPhN, 91191 Gif-sur-Yvette, Cedex (France); Schumann, D.; Neuhausen, J. [Paul Scherrer Institut, Villigen (Switzerland); Zanini, L. [Paul Scherrer Institut, Villigen (Switzerland); European Spallation Source ESS AB, P.O. Box 117, SE-22100 Lund (Sweden); Noah, E. [University of Geneva, Département de Physique Nucléaire et Corpusculaire, Geneve (Switzerland)


    We measured the isotopic concentrations of long-lived and stable He, Ne, Ar, Kr, and Xe isotopes in a sample from a lead-bismuth eutectic target irradiated with 1.0 and 1.4 GeV protons. Our data indicate for most noble gases nearly complete release with retention fractions in the range of percent or less. Higher retention fractions result from the decay of long-lived radioactive progenitors from groups 1, 2, or 7 of the periodic table. From the data we can calculate a retention fraction for {sup 3}H of 2–3%. For alkaline metals we find retention fractions of about 10%, 30%, and 50% for Na, Rb, and Cs, respectively. For the alkaline earth metal Ba we found complete retention. Finally, the measured Kr and Xe concentrations indicate that there was some release of the halogens Br and I during and/or after the irradiation.

  1. Addition of ash on drained forested peatlands in southern Sweden. Effects on forest production, fluxes of greenhouse gases and water chemistry; Tillfoersel av aska i tallskog paa dikad torvmark i soedra Sverige. Effekter paa skogsproduktion, avgaang av vaexthusgaser och vattenkemi

    Energy Technology Data Exchange (ETDEWEB)

    Sikstroem, Ulf; Jacobson, Staffan; Ring, Eva [Skogforsk, Uppsala (Sweden); Ernfors, Maria; Klemedtsson, Leif [Goeteborg Univ. (Sweden). Dept. of Plant and Environmental Sciences; Nilsson, Mats [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden)


    In Sweden, about one million tones of wood ashes are produced annually, of which about 250,000-300,000 tones originate from biofuels, e.g. forest residues. Some of the ashes produced are deposited today. One alternative use is bringing back the ashes to the forest, recycling the mineral nutrients and base compounds. In bioashes, most essential mineral nutrients for plants are included, except for N, which is gasified at combustion. On most mineral soils in Sweden, plant available nitrogen is the nutrient limiting tree growth. On organic soils, tree growth is usually increased after addition of phosphorous and potassium. Thus, there is a potential for increased forest production on peatlands after ash fertilization. This can be a profitable measure. Nutrient compensation after harvesting involve ash addition with quite low doses. This is especially important in peatlands after whole-tree harvesting in order to prevent nutrient deficiency and reduced tree growth. However, there is a need for better knowledge concerning other environmental effects before ash addition can be put into large-scale practice. The general objective of this project is to study the effects of wood-ash addition on forest production and some other environmental variables on drained, forested peatlands. The studies concern tree growth, emissions of greenhouse gases and water chemistry (ground water and run off). An important issue addressed was if an expected increased accumulation of carbon (CO{sub 2}) due to increased tree growth can compensate for an expected increased emission of greenhouse gases (e.g. CO{sub 2} and CH{sub 4}) from the peat. In addition, the very effective greenhouse gas laughing gas (N{sub 2}O), must be taken into consideration. In 2003, two field experiments were established in the county of Smaaland in southeast Sweden, where wood ashes from biofuels were applied. One experiment was designed as a randomized block experiment (273 Anderstorp) where effects on forest

  2. Addition of ash on drained forested peatlands in southern Sweden. Effects on forest production, fluxes of greenhouse gases and water chemistry; Tillfoersel av aska i tallskog paa dikad torvmark i soedra Sverige. Effekter paa skogsproduktion, avgaang av vaexthusgaser och vattenkemi

    Energy Technology Data Exchange (ETDEWEB)

    Sikstroem, Ulf; Ernfors, Maria; Jacobson, Staffan; Klemedtsson, Leif; Nilsson, Mats; Ring, Eva


    In Sweden, about one million tones of wood ashes are produced annually, of which about 250,000 - 300,000 tones originate from forest residues. Some of the ashes produced are deposited today. One alternative use is bringing back the ashes to the forest, recycling the mineral nutrients and base compounds. In bioashes, most essential mineral nutrients for plants are included, except for N, which is gasified at combustion. On most mineral soils in Sweden, plant available nitrogen is the nutrient limiting tree growth. On organic soils, tree growth is usually increased after addition of phosphorous and potassium. Thus, there is a potential for increased forest production on peatlands after ash fertilization. This can be a profitable measure. Nutrient compensation after harvesting involve ash addition with quite low doses. This is especially important in peatlands after whole-tree harvesting in order to prevent nutrient deficiency and reduced tree growth. However, there is a need for better knowledge concerning other environmental effects before ash addition can be put into large-scale practice. The general objective of this project is to study the effects of wood-ash addition on forest production and some other environmental variables on drained, forested peatlands. The studies concern tree growth, emissions of greenhouse gases and water chemistry (ground water and run off). An important issue addressed was if an expected increased accumulation of carbon (CO{sub 2}) due to increased tree growth can compensate for an expected increased emission of greenhouse gases (e.g. CO{sub 2} and CH{sub 4}) from the peat. In addition, the very effective greenhouse gas laughing gas (N2O), must be taken into consideration. In 2003, two field experiments were established in the county of Smaaland in south Sweden, where wood ashes from biofuels were applied. One experiment was designed as a randomized block experiment where effects on forest production and greenhouse gases (CO{sub 2}, CH

  3. Absorption spectroscopy of xenon and ethylene-noble gas mixtures at high pressure: Towards Bose-Einstein condensation of vacuum ultraviolet photons

    CERN Document Server

    Wahl, Christian; Schmitt, Julian; Vewinger, Frank; Christopoulos, Stavros; Weitz, Martin


    Bose-Einstein condensation is a phenomenon well known for material particles as cold atomic gases, and this concept has in recent years been extended to photons confined in microscopic optical cavities. Essential for the operation of such a photon condensate is a thermalization mechanism that conserves the average particle number, as in the visible spectral regime can be realized by subsequent absorption re-emission processes in dye molecules. Here we report on the status of an experimental effort aiming at the extension of the concept of Bose-Einstein condensation of photons towards the vacuum ultraviolet spectral regime, with gases at high pressure conditions serving as a thermalization medium for the photon gas. We have recorded absorption spectra of xenon gas at up to 30 bar gas pressure of the $5p^6 - 5p^56s$ transition with a wavelength close to 147 nm. Moreover, spectra of ethylene noble gas mixtures between 155 and 180 nm wavelength are reported.

  4. Radiolytic model of CN Cofrentes using BWRVIA: analysis of the effectiveness of mitigation in locations of the vessel with application of noble metal son-line; Modelo radiolitico de C. N: Cofrentes utilizando el BWRVIA: analisis de la efectividad de mitigacion en localizaciones de la vasija con aplicacion de metales nobles on-line

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Serrano Ledesma, C.; Sanchez Zapata, J. D.


    The effectiveness of mitigation is found from two chemical parameters: electrochemical potential (pm-a hydrogen injection) and Molar Ratio (for the application of noble metals). EPRI code exists, the BWRVIA (BWR Vessel Internals Application,) which enables setting model the impact radiolysis of water, the balance of liquid-vapor phase and recirculation have on the chemical variation of these parameters.

  5. Desulphurization of exhaust gases in chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, K.; Wischnewski, W.


    The sulfur content of exhaust gases can be reduced by: desulphurization of fuels; modification of processes; or treatment of resultant gases. In this paper a few selected examples from the chemical industry in the German Democratic Republic are presented. Using modified processes and treating the resultant gases, the sulphuric content of exhaust gases is effectively reduced. Methods to reduce the sulfur content of exhaust gases are described in the field of production of: sulphuric acid; viscose; fertilizers; and paraffin.

  6. Stress analysis of the O-element pipe during the process of flue gases purification

    Directory of Open Access Journals (Sweden)

    Nekvasil R.


    Full Text Available Equipment for flue gases purification from undesired substances is used throughout power and other types of industry. This paper deals with damaging of the O-element pipe designed to remove sulphur from the flue gases, i.e. damaging of the pipe during flue gases purification. This purification is conducted by spraying the water into the O-shaped pipe where the flue gases flow. Thus the sulphur binds itself onto the water and gets removed from the flue gas. Injection of cold water into hot flue gases, however, causes high stress on the inside of the pipe, which can gradually damage the O-element pipe. In this paper initial injection of water into hot pipe all the way to stabilization of temperature fields will be analyzed and the most dangerous places which shall be considered for fatigue will be determined.

  7. Study and full simulation of ten different gases on sealed Multi-Wire Proportional Counter (MWPC) by using Garfield and Maxwell codes. (United States)

    Shohani, M Ebrahimi; Golgoun, S M; Aminipour, M; Shabani, A; Mazoochi, A R; Akbari, R Maghsoudi; Mohammadzadeh, M; Davarpanah, M R; Sardari, D; Sadeghi, M; Mofrad, F Babapour; Jafari, A


    In this research gas sealed Multi-Wire Proportional Counter (MWPC) including blades between anode wires and beta particles of (90)Sr with 196keV mean energy were considered. Ten different gases such as Noble gases mixtures with methane and several other pure gases were studied. In this type of detector, by using Garfield and Maxwell codes and for each of the gases, variation of different parameters such as first Townsend, electron attachment coefficients with variable electric field and their effects on pulse height or collected charge and in turn on Signal to Noise Ratio (SNR) were studied. Also the effect of anode voltage and its diameter and the pressure of gas on the pulse height were studied. Results show that Garfield and Maxwell codes can be used to study and improve the design of other gaseous detectors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. [CFC gases in medicinal sprays]. (United States)

    Pedersen, P H; Svendsen, U G


    In 1987, approximately 1.18 million aerosol dispensers for medicinal use were sold in Denmark. These contained approximately 29 tons of completely halogenized CFC gases ("Freon") and the preparations were employed for the treatment of bronchial asthma and rhinitis. The possibilities of substitutes are discussed in this article. Preparations are already available which do not contain CFC. Producers of CFC are also attempting to develop new aerosol gases which do not damage the environment. Perhaps these will be found in medicinal preparations in the future.

  9. Electrocatalysis of chemically synthesized noble metal nanoparticles on carbon electrodes

    DEFF Research Database (Denmark)

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    conductivity, chemical inertness and low cost. Improvement of catalytic efficiency and stability of the NPs is, however, essential for their wider applications in electrochemical energy conversion/storage. The activities of noble metal catalysts depend not only on their size, composition, and shapes but also......Noble metal nanoparticles (NPs), such as platinum (Pt) and palladium (Pd) NPs are promising catalysts for dioxygen reduction and oxidation of molecules such as formic acid and ethanol in fuel cells. Carbon nanomaterials are ideal supporting materials for electrochemical catalysts due to their good...... by electrochemical SPM. This study offers promise for development of new high-efficiency catalyst types with low-cost for fuel cell technology...

  10. Novel System for Continuous Measurements of Dissolved Gases in Liquids (United States)

    Baer, D. S.; Liem, J.; Owano, T. G.; Gupta, M.


    Measurements of dissolved gases in lakes, rivers and oceans may be used to quantify underwater greenhouse gas generation, air-surface exchange, and pollution migration. Studies involving quantification of dissolved gases typically require obtaining water samples (from streams, lakes, or ocean water) and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line, discrete-sample methodology is time consuming and labor intensive, and thus severely inhibits detailed spatial and temporal mapping of dissolved gases. In this work, we describe the commercial development of a new portable membrane-based gas extraction system (18.75" x 18.88" x 10.69", 16 kg, 85 watts) that interfaces directly to our cavity enhanced laser absorption based (or Off-Axis ICOS) gas analyzers to continuously and quickly measure concentrations and isotope ratios of dissolved gases. By accurately controlling the water flow rate through the membrane contactor, gas pressure on the outside and water pressure on the inside of the membrane, the system can generate precise and highly reproducible results. Furthermore, the gas-phase mole fractions (parts per million, ppm) may be converted into dissolved gas concentrations (nM), by accurately measuring the gas flow rates in and out of the extraction system. We will present detailed laboratory test data that quantifies the performance (linearity, precision, and dynamic range) of the system for measurements of the concentrations and isotope ratios of dissolved greenhouse gases (methane, carbon dioxide, and nitrous oxide) continuously and in real time.

  11. Liquid noble gas detectors for low energy particle physics


    Chepel, Vitaly; Araújo, Henrique


    We review the current status of liquid noble gas radiation detectors with energy threshold in the keV range, wich are of interest for direct dark matter searches, measurement of coherent neutrino scattering and other low energy particle physics experiments. Emphasis is given to the operation principles and the most important instrumentation aspects of these detectors, principally of those operated in the double-phase mode. Recent technological advances and relevant developments in photon dete...

  12. Possible solar noble-gas component in Hawaiian basalts (United States)

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.


    THE noble-gas elemental and isotopic composition in the Earth is significantly different from that of the present atmosphere, and provides an important clue to the origin and history of the Earth and its atmosphere. Possible candidates for the noble-gas composition of the primordial Earth include a solar-like component, a planetary-like component (as observed in primitive meteorites) and a component similar in composition to the present atmosphere. In an attempt to identify the contributions of such components, we have measured isotope ratios of helium and neon in fresh basaltic glasses dredged from Loihi seamount and the East Rift Zone of Kilauea1-3. We find a systematic enrichment in 20Ne and 21Ne relative to 22Ne, compared with atmospheric neon. The helium and neon isotope signatures observed in our samples can be explained by mixing of solar, present atmospheric, radiogenic and nucleogenic components. These data suggest that the noble-gas isotopic composition of the mantle source of the Hawaiian plume is different from that of the present atmosphere, and that it includes a significant solar-like component. We infer that this component was acquired during the formation of the Earth.

  13. Noble Gases in the Monahans Chondrite and Halite: Ar-39 - Ar-40 Age, Space Exposure Age, Trapped Solar Gases, and Neutron Fluence (United States)

    Garrison, Daniel H.; Bogard, Donald D.


    For the Monahans chondrite and halite, we determined Ar-39 - Ar-40 ages of silicate = 4.53 Ga, halite > 4.3 Ga; a space exposure age of approx. 5 Ma; a regolith pre-irradiation; solar gas concentrations in the dark phase; and a regolith thermal neutron fluence.

  14. Mitigation options for accidental releases of hazardous gases

    Energy Technology Data Exchange (ETDEWEB)

    Fthenakis, V.M.


    The objective of this paper is to review and compare technologies available for mitigation of unconfined releases of toxic and flammable gases. These technologies include: secondary confinement, deinventory, vapor barriers, foam spraying, and water sprays/monitors. Guidelines for the design and/or operation of effective post-release mitigation systems and case studies involving actual industrial mitigation systems are also presented.

  15. Cucurbit[6]uril: A Possible Host for Noble Gas Atoms. (United States)

    Pan, Sudip; Mandal, Subhajit; Chattaraj, Pratim K


    Density functional and ab initio molecular dynamics studies are carried out to investigate the stability of noble gas encapsulated cucurbit[6]uril (CB[6]) systems. Interaction energy, dissociation energy and dissociation enthalpy are calculated to understand the efficacy of CB[6] in encapsulating noble gas atoms. CB[6] could encapsulate up to three Ne atoms having dissociation energy (zero-point energy corrected) in the range of 3.4-4.1 kcal/mol, whereas due to larger size, only one Ar or Kr atom encapsulated analogues would be viable. The dissociation energy value for the second Ar atom is only 1.0 kcal/mol. On the other hand, the same for the second Kr is -0.5 kcal/mol, implying the instability of the system. The noble gas dissociation processes are endothermic in nature, which increases gradually along Ne to Kr. Kr encapsulated analogue is found to be viable at room temperature. However, low temperature is needed for Ne and Ar encapsulated analogues. The temperature-pressure phase diagram highlights the region in which association and dissociation processes of Kr@CB[6] would be favorable. At ambient temperature and pressure, CB[6] may be used as an effective noble gas carrier. Wiberg bond indices, noncovalent interaction indices, electron density, and energy decomposition analyses are used to explore the nature of interaction between noble gas atoms and CB[6]. Dispersion interaction is found to be the most important term in the attraction energy. Ne and Ar atoms in one Ng entrapped analogue are found to stay inside the cavity of CB[6] throughout the simulation at 298 K. However, during simulation Ng2 units in Ng2@CB[6] flip toward the open faces of CB[6]. After 1 ps, one Ne atom of Ne3@CB[6] almost reaches the open face keeping other two Ne atoms inside. At lower temperature (77 K), all the Ng atoms in Ngn@CB[6] remain well inside the cavity of CB[6] throughout the simulation time (1 ps).

  16. Electrochemical Synthesis of Nanostructured Noble Metal Films for Biosensing (United States)

    Bhattarai, Jay K.

    Nanostructures of noble metals (gold and silver) are of interest because of their important intrinsic properties. Noble metals by themselves are physically robust, chemically inert, highly conductive, and possess the capability to form strong bonds with thiols or dithiol molecules present in organic compounds, creating self-assembled monolayers with tunable functional groups at exposed interfaces. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties which can be tuned by adjusting the shape and the size of the nanostructures. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for optical and electrochemical biosensing. Individual nanostructures might be easier to prepare but difficult to handle to use as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble metals and used them as a transducer for optical and electrochemical biosensing. We have electrochemically prepared nanoporous gold (NPG) on gold wire varying different dependable parameters (deposition potential, time, and compositional ratio) to obtain an optimal structure in term of stability, morphology, and better surface area. NPG prepared using a deposition potential of --1.0 V for 10 min from 30:70% 50 mM potassium dicyanoaurate(I) and 50 mM potassium dicyanoargentate(I) was used as an optimal surface for protein immobilization, and to perform square wave voltammetry (SWV) based enzyme-linked lectinsorbent assays. On flat gold surfaces, adjacent protein molecules sterically block their active sites due to high-density packing, which can be minimized using NPG as a substrate. NPG can also show significant peak current in SWV experiments, a sensitive electrochemical technique that minimizes non-Faradaic current, which is difficult to obtain using a flat gold surface. These all make NPG a suitable substrate, electrode, and transducer to be used in

  17. Elucidation of noble metal/formic acid chemistry during DWPF feed preparation. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Landon, L.F.


    Eleven reports are included: evaluation of noble metal compounds as catalysts for aerobic decomposition of formic acid; reaction of NaNO{sub 3} and NaNO{sub 2} with formic acid under argon; effects of Ru, Rh, Pd chlorides on formic acid decomposition in presence of IDMS (pH=11.0) sludge; effects of additives on catalysts on decomposition of formic acid to hydrogen; Rh-catalyzed decomposition of formic acid; the question of whether this decomposition can be heterogeneous catalysis; inhibition of this reaction by additives; nitrilotriacetic acid inhibitor; uses of gelatin and other water soluble polymers to control flocculation rate; comparison of catalytic activities of Rh, Ru, Pd in Purex and HM sludges; experiments on homogeneous vs heterogeneous nature of Rh catalyst. Figs, refs, tabs.

  18. Structure and optical properties of noble metal and oxide nanoparticles dispersed in various polysaccharide biopolymers (United States)

    Djoković, V.; Božanic, D. K.; Vodnik, V. V.; Krsmanović, R. M.; Trandafilovic, L. V.; Dimitrijević-Branković, S.


    We present the results on the structure and the optical properties of noble metal (Ag, Au) and oxide (ZnO) nanoparticles synthesized by various methods in different polysaccharide matrices such as chitosan, glycogen, alginate and starch. The structure of the obtained nanoparticles was studied in detail with microscopic techniques (TEM, SEM), while the XPS spectroscopy was used to investigate the effects at the nanoparticle-biomolecule interfaces. The antimicrobial activity of the nanocomposite films with Ag nanoparticles was tested against the Staphylococcus aureus, Escherichia coli and Candida albicans pathogens. In addition, we will present the results on the structure and optical properties of the tryptophan amino acid functionalized silver nanoparticles dispersed in water soluble polymer matrices.

  19. EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases (United States)

    Vassen, W.; Hemmerich, A.; Arimondo, E.


    This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by

  20. Noble gases, C,N, and Si isotopes in interstellar SiC form the Murchison carbonaceous chondrite (United States)

    Ming, Tang; Anders, Edward; Zinner, Ernst


    Isotopic measurements of presolar interstellar silicon carbide are presented. Silicon carbide was recently identified in a primitive meteorite Murray. There exists strong evidence that the silicon carbide predates the formation of the solar system and originated in the atmospheres of certain stars. Thus, this material provides a link with its stellar sources and gives the opportunity to study processes taking place in distant stars.

  1. Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8. (United States)

    Magdysyuk, O V; Adams, F; Liermann, H-P; Spanopoulos, I; Trikalitis, P N; Hirscher, M; Morris, R E; Duncan, M J; McCormick, L J; Dinnebier, R E


    An experimental study of Xe and Kr adsorption in metal-organic frameworks CPO-27-Ni, CPO-27-Mg, and ZIF-8 was carried out. In situ synchrotron X-ray powder diffraction experiments allowed precise determination of the adsorption sites and sequence of their filling with increasing of gas pressure at different temperatures. Structural investigations were used for interpretation of gas adsorption measurements.

  2. Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

    NARCIS (Netherlands)

    Bense, V.F.; Gumm, L.P.; Dennis, P.; Hiscock, N.; Cremer, N.; Simon, S.


    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is

  3. Dissociative and non-dissociative electron capture by keV diatomic molecular ions from noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Nora G; Sayler, A M; McKenna, J; Gaire, B; Zohrabi, M; Berry, Ben; Carnes, K D; Ben-Itzhak, I [J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS 66506 (United States); Wolff, Wania, E-mail: ibi@phys.ksu.ed [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21945-970, RJ (Brazil)


    Dissociative and non-dissociative electron capture from atoms by slow molecular ions were investigated by measuring in coincidence the momenta of the recoil ion and the projectile or its fragment pair. From these momenta we evaluate the reaction Q-value as well as the scattering angles. For the dissociative capture we also determine the alignment dependence of the process.

  4. Proton affinities of maingroup-element hydrides and noble gases: trends across the periodic table, structural effects, and DFT validation

    NARCIS (Netherlands)

    Swart, M.; Rosler, E.; Bickelhaupt, F.M.


    We have carried out an extensive exploration of the gas-phase basicity of archetypal neutral bases across the periodic system using the generalized gradient approximation (GGA) of the density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing

  5. Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany (United States)

    Gumm, L. P.; Bense, V. F.; Dennis, P. F.; Hiscock, K. M.; Cremer, N.; Simon, S.


    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7 × 10-4 cm3 (STP) g-1 ± 2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ˜107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study's geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.

  6. Dissolved noble gases, stable isotopes and heat as tracers of preferential fluid flow along faults in unconsolidated sedimentary aquifer systems (United States)

    Bense, V.


    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge and 4He concentrations up to 1.7×10-4 cm³ (STP) gˉ¹ ± 2.2% which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age-dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of 107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, our geochemical data suggest for the first time that deep circulating fluids penetrate shallow aquifers in the locality of fault zones and that sub-vertical fluid flow occurs along faults in the LRE. Large hydraulic head gradients observed across many faults in the LRE, but which is a global phenomenon, suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate the previously proposed conduit-barrier model of fault zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for Carbon Capture and Storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.

  7. Removal of sulfur and nitrogen containing pollutants from discharge gases

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, J.I.


    Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

  8. Removal of sulfur and nitrogen containing pollutants from discharge gases

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, James I. (Pittsburgh, PA)


    Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

  9. Towards redistribution laser cooling of molecular gases: Production of candidate molecules SrH by laser ablation

    CERN Document Server

    Simon, Philipp; Weller, Lars; Sass, Anne; Weitz, Martin; 10.1117/12.2002379


    Laser cooling by collisional redistribution of radiation has been successfully applied in the past for cooling dense atomic gases. Here we report on progress of work aiming at the demonstration of redistribution laser cooling in a molecular gas. The candidate molecule strontium monohydride is produced by laser ablation of strontium dihydride in a pressurized noble gas atmosphere. The composition of the ablation plasma plume is analyzed by measuring its emission spectrum. The dynamics of SrH molecular density following the ablation laser pulse is studied as a function of the buffer gas pressure and the laser intensity.

  10. Characterization of the electrochemical behavior of coating by steel welding 308l and in presence of noble metals deposits; Caracterizacion del comportamiento electroquimico de recubrimiento por soldadura de acero 308L y en presencia de depositos de metales nobles

    Energy Technology Data Exchange (ETDEWEB)

    Piedras, P.; Arganis J, C. R., E-mail: [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)


    In this work the oxide deposits and noble metals deposit were characterized (Ag and Pt) on a coating of stainless steel 308l that were deposited by the shield metal arc welding (SMAW) on steel A36 by means of scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The extrapolation of Tafel technique was also used to obtain the corrosion potential (Ec) for the pre-rusty steel and for the samples with deposits of Pt and Ag under conditions of hydrogen water chemistry (HWC), demonstrating that this parameter diminishes with the presence of this deposits. (Author)

  11. Noble Metals and Spinel Settling in High Level Waste Glass Melters

    Energy Technology Data Exchange (ETDEWEB)

    Sundaram, S. K.; Perez, Joseph M.


    In the continuing effort to support the Defense Waste Processing Facility (DWPF), the noble metals issue is addressed. There is an additional concern about the amount of noble metals expected to be present in the future batches that will be considered for vitrification in the DWPF. Several laboratory, as well as melter-scale, studies have been completed by various organizations (mainly PNNL, SRTC, and WVDP in the USA). This letter report statuses the noble metals issue and focuses at the settling of noble metals in melters.

  12. Control of pollutants in flue gases and fuel gases

    Energy Technology Data Exchange (ETDEWEB)

    Zevenhoven, R. [Helsinki Univ. of Technology, Otaniemi (Finland); Kilpinen, P. [Aabo Akademi Univ., Turku (Finland)


    Funding from the Nordic Energy Research Programme and from Helsinki University of Technology allowed for the preparation of this e-book, accompanied by overhead sheets as presented during the lectures. All material can be downloaded as pdf documents from the internet-address, hence the qualification e- book Updates will be produced chapter-by-chapter in the future. Objectives and scope. Textbooks on this subject are, in general, limited to what can be called 'conventional' flue gas cleaning for conventional pulverised coal combustion processes, i.e. wet flue gas desulphurisation (FGD), bag filters and electrostatic precipitators for flyash and selective catalytic reduction (SCR) for NO{sub x} control. Other books address waste incineration within a discussion on waste management. The scope of this material we tried to make more up-to-date and therefore wider than these texts. Apart from pollutant control the formation of the pollutants is briefly addressed, which often provides the key to abatement methods as an alternative to control methods. Secondly, more species are addressed such HS in addition to SO{sub 2}; N{sub 2}0, HCN and NH{sub 3} in addition to NO{sub x}; alkali metals and trace elements such as mercury, halogenic compounds such as HO and dioxines and furanes; and volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Also greenhouse gases, mainly CO{sub 2}, and ozone-depleting gases, such as CFCs, are briefly discussed. The motivation for this was to cover flue gases from combustion as well as fuel gases from gasification processes, using various types of furnaces and boilers, and to extend the range of chemical compounds to those found in the product gases in waste incineration and energy-from-waste processes. Finally, not only 'cold' gas cleaning but also 'hot' gas cleaning is addressed. All this in an attempt to cover the wide spectrum of pollutants found in

  13. Control of pollutants in flue gases and fuel gases

    Energy Technology Data Exchange (ETDEWEB)

    Zevenhoven, R.; Kilpinen, P.


    Textbooks on this subject are, in general, limited to what can be called 'conventional' flue gas cleaning for conventional pulverised coal combustion processes, i.e. wet flue gas desulphurisation (FGD), bag filters and electrostatic precipitators for flyash and selective catalytic reduction (SCR) for NO{sub x} control. Other books address waste incineration within a discussion on waste management. The scope of this material we tried to make more up-to-date and therefore wider than these texts. Apart from pollutant control the formation of the pollutants is briefly addressed, which often provides the key to abatement methods as an alternative to control methods. Secondly, more species are addressed such HS in addition to SO{sub 2}; N{sub 2}O, HCN and NH{sub 3} in addition to NO{sub x}; alkali metals and trace elements such as mercury, halogenic compounds such as HO and dioxines and furanes; and volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Also greenhouse gases, mainly CO{sub 2}, and ozone-depleting gases, such as CFCs, are briefly discussed. The motivation for this was to cover flue gases from combustion as well as fuel gases from gasification processes, using various types of furnaces and boilers, and to extend the range of chemical compounds to those found in the product gases in waste incineration and energy-from- waste processes. Finally, not only 'cold' gas cleaning but also 'hot' gas cleaning is addressed. All this in an attempt to cover the wide spectrum of pollutants found in gas streams in modern thermal power generation processes, being based on combustion or gasification, with a fossil fuel, biomass or waste-derived fuel as input. Recovery boilers for black liquor are, however, not specifically-dealt with. Updates of the textbook has been produced and will also be so in future chapter by chapter. For the third edition, tine latest emission standards data for SO{sub x}, NO{sub x} and

  14. Landfill gases and some effects on vegetation (United States)

    Franklin B. Flower; Ida A. Leone; Edward F. Gilman; John J. Arthur


    Gases moving from refuse landfills through soil were studied in New Jersey. The gases, products of anaerobic decomposition of organic matter in the refuse, caused injury and death of peach trees, ornamentals, and commercial farm crops, and create possible hazards to life and property because of the entrance of combustible gases into residences. Remedial measures are...

  15. Theoretical Insight into Shocked Gases

    Energy Technology Data Exchange (ETDEWEB)

    Leiding, Jeffery Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    I present the results of statistical mechanical calculations on shocked molecular gases. This work provides insight into the general behavior of shock Hugoniots of gas phase molecular targets with varying initial pressures. The dissociation behavior of the molecules is emphasized. Impedance matching calculations are performed to determine the maximum degree of dissociation accessible for a given flyer velocity as a function of initial gas pressure.

  16. Dipolar quantum gases and liquids (United States)

    Pfau, Tilman


    Dipolar interactions are fundamentally different from the usual van der Waals forces in real gases. Besides the anisotropy the dipolar interaction is nonlocal and as such allows for self organized structure formation. Candidates for dipolar species are polar molecules, Rydberg atoms and magnetic atoms. More than ten years ago the first dipolar effects in a quantum gas were observed in an ultracold Chromium gas. By the use of a Feshbach resonance a purely dipolar quantum gas was observed three years after. By now dipolar interaction effects have been observed in lattices and also for polar molecules. Recently it became possible to study degenerate gases of lanthanide atoms among which one finds the most magnetic atoms. Similar to the Rosensweig instability in classical magnetic ferrofluids self-organized structure formation was expected. In our experiments with quantum gases of Dysprosium atoms we could recently observe the formation of a droplet crystal. In contrast to theoretical mean field based predictions the superfluid droplets did not collapse. We find that this unexpected stability is due to beyond meanfield quantum corrections of the Lee-Huang-Yang type. We observe and study self-bound droplets which can interfere with each other. These droplets are 100 million times less dense than liquid helium droplets and open new perspectives as a truly isolated quantum system.

  17. Shear bond strength of a ceromer to noble and base metal alloys

    Directory of Open Access Journals (Sweden)

    Dorriz H.


    Full Text Available Background and Aim: The improvement of the physical and chemical properties of resins as well as great advances achieved in the field of chemical bonding of resin to metal has changed the trend of restorative treatments. Today the second generation of laboratory resins have an important role in the restoration of teeth. The clinical bond strength should be reliable in order to gain successful results. In this study the shear bond strength (SBS between targis (a ceromer and two alloys (noble and base metal was studied and the effect of thermocycling on the bond investigated. Materials and Methods: In this experimental study, alloys samples were prepared according to the manufacturer. After sandblasting of bonding surfaces with 50µ AI2o3 Targis was bonded to the alloy using Targis I link. All of the samples were placed in 37°C water for a period of 24 hours. Then half of the samples were subjected to 1000 cycles of thermocycling at temperatures of 5°C and 55°C. Planear shear test was used to test the bond strength in the Instron machine with the speed rate of 0.5mm/min. Data were analyzed by SPSS software. Two-way analysis of variance was used to compare the bond strength among the groups. T test was used to compare the alloys. The influence of thermocycling and alloy type on bond strength was studied using Mann Whitney test. P<0.05 was considered as the limit of significance. Result: The studied alloys did not differ significantly, when the samples were not thermocycled (P=0.136 but after thermocycling a significant difference was observed in SBS of resin to different alloys (P=000.1. Thermal stress and alloy type had significant interaction, with regard to shear bond strength (P=0.003. There was a significant difference in SBS before and after thermocycling in noble alloys (P=0.009, but this was not true in base metals (P=0.29. Maximum SBS (19.09 Mpa belonged to Degubond 4, before thermocycling. Minimum SBS (8.21 Mpa was seen in Degubond 4

  18. Genealogía de la noble mentira

    Directory of Open Access Journals (Sweden)

    Miguel Catalán


    Full Text Available Cet article analyse la notion de « noble mensonge » que l’on retrouve tout au long de l’histoire chez de nombreux auteurs, de Platon dans la Republique à Leo Strauss, l’actuel inspirateur de la politique menée par les néo-conservateurs aux Etats-Unis. L’article trace une ligne de pensée qui traverse les principales écoles et les auteurs modernes qui ont justifié le mensonge politique.The notion of «noble lie» has a long history. It can be found from Plato’s Republic to Leo Strauss’opus, a contemporary thinker whose thought inspires the philosophical background of the North-American neo-conservatives, who control the present Republican administration. This article goes through and analyses the main modern schools and authors who have justified political lie, i.e. a specific lie by which the political authority deceives its own people.Partiendo de la noción de «noble mentira» que encontramos en República de Platón y desembocando en la figura de Leo Strauss, filósofo inspirador de los actuales políticos neo-conservadores norteamericanos en torno al partido republicano en el poder, este artículo traza una línea de pensamiento que recorre las principales escuelas y autores modernos que han justificado la mentira política, entendida como aquella mentira con que el gobernante engaña a sus gobernados.

  19. Status of QUPID, a novel photosensor for noble liquid detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pantic, E., E-mail: [Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Aharoni, D.; Arisaka, K.; Beltrame, P.; Brown, E.; Cline, D. [Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Fukasawa, A. [Electron Tube Division, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata City 438-0193, Shizuoka (Japan); Ghag, C.; Lam, C.W.; Lim, T.; Lung, K.; Meng, Y. [Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Muramatsu, S. [Electron Tube Division, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata City 438-0193, Shizuoka (Japan); Scovell, P. [Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Suyama, M. [Electron Tube Division, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata City 438-0193, Shizuoka (Japan); Teymourian, A.; Wang, H. [Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095 (United States)


    The discovery potential of experiments searching for rare events, such as dark matter interaction, relies heavily upon achieving a very low background environment. The current generation of noble liquid dark matter detectors is limited by the radioactivity in the detector materials, mostly from the photomultiplier tubes. Quartz Photon Intensifying Detector (QUPID) is a novel photosensor based upon hybrid APD technology and with intrinsic radioactivity at least an order of magnitude lower than the presently employed phototubes. The basic concept as well as the status and the prospect of the QUPID are reviewed. The performance of the QUPID as photosensor for the ultraviolet scintillation light of liquid xenon is presented.

  20. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    Incredibly vast advance has been achieved in fuel cell technology regarding to catalyst efficiency, improvement of electrolyte conductivity and optimization of cell system. With breathtakingly accelerating progress, Proton Exchange Membrane Fuel Cells (PEMFC) is the most promising and most widely....... Membrane Electrode Assembly (MEA) is commonly considered as the heart of cell system [2]. Degradation of the noble metal catalysts in MEAs especially Three-Phase-Boundary (TPB) is a key factor directly influencing fuel cell durability. In this work, electrochemical degradation of Pt and Pt/Ru alloy were...

  1. Noble Gas Clusters and Nanoplasmas in High Harmonic Generation

    CERN Document Server

    Aladi, M; Rácz, P; Földes, I B


    We report a study of high harmonic generation from noble gas clusters of xenon atoms in a gas jet. Harmonic spectra were investigated as a function of backing pressure, showing spectral shifts due to the nanoplasma electrons in the clusters. At certain value of laser intensity this process may oppose the effect of the well-known ionization-induced blueshift. In addition, these cluster-induced harmonic redshifts may give the possibility to estimate cluster density and cluster size in the laser-gas jet interaction range.

  2. Risks to Water Resources from Shale Gas Development and Hydraulic Fracturing in the United States (United States)

    Vengosh, Avner; Jackson, Robert B.; Warner, Nathaniel; Darrah, Thomas H.; Kondash, Andrew


    The rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded oil and gas exploration in the USA. The rapid rate of shale gas exploration has triggered an intense public debate regarding the potential environmental and human health effects. A review of the updated literature has identified four potential risks for impacts on water resources: (1) stray gas contamination of shallow aquifers near shale gas sites; (2) contamination of surface water and shallow groundwater from spills, leaks, and disposal of inadequately treated wastewater or hydraulic fracturing fluids; (3) accumulation of toxic and radioactive residues in soil or stream sediments near disposal or spill sites; and (4) over-extraction of water resources for drilling and hydraulic fracturing that could induce water shortages and conflicts with other water users, particularly in water-scarce areas. As part of a long-term research on the potential water contamination associated with shale gas development, new geochemical and isotopic techniques have been developed for delineating the origin of gases and contaminants in water resource. In particular, multiple geochemical and isotopic (carbon isotopes in hydrocarbons, noble gas, strontium, boron, radium isotopes) tracers have been utilized to distinguish between naturally occurring dissolved gas and salts in water and contamination directly induced from shale gas drilling and hydraulic fracturing operations.

  3. Efficient photorecovery of noble metals from solution using a γ-SiW10O36/surfactant hybrid photocatalyst. (United States)

    Kida, Tetsuya; Matsufuji, Hiromasa; Yuasa, Masayoshi; Shimanoe, Kengo


    In recent years, the recovery of noble metals from waste has become very important because of their scarcity and increasing consumption. In this study, we attempt the photochemical recovery of noble metals from solutions using inorganic-organic hybrid photocatalysts. These catalysts are based on polyoxometalates such as PMo(12)O(40)(3-), SiW(12)O(40)(4-), and γ-SiW(10)O(36)(8-) coupled with a cationic surfactant, dimethyldioctadecylammonium (DODA). The three different photocatalysts dissolved in chloroform were successful in photoreducing gold ions dissolved in water in a two-phase (chloroform/water) system under UV irradiation (λ SiW(10)O(36)/DODA photocatalyst exhibited the best activity and recovered gold from solution efficiently. It was suggested that one-electron reduced γ-SiW(10)O(36)(9-) formed by the UV irradiation reduced gold ions. As a result, large two-dimensional particles (gold nanosheets) were produced using the γ-SiW(10)O(36)/DODA photocatalyst, indicating that the reduction of gold ions occurred at the interface between chloroform and water. The γ-SiW(10)O(36)/DODA photocatalyst was able to recover metals such as platinum, silver, palladium, and copper from deaerated solutions. The selective recovery of gold is possible by controlling pH and oxygen concentration in the reaction system.

  4. Stepwise heating of lunar anorthosites 60025, 60215, 65315 possibly reveals an indigenous noble gas component on the Moon (United States)

    Bekaert, David V.; Avice, Guillaume; Marty, Bernard; Henderson, Bryana; Gudipati, Murthy S.


    Despite extensive effort during the last four decades, no clear signature of a lunar indigenous noble gas component has been found. In order to further investigate the possible occurrence of indigenous volatiles in the Moon, we have re-analyzed the noble gas and nitrogen isotopic compositions in three anorthosite samples. Lunar anorthosites 60025, 60215 and 65315 have the lowest exposure duration (∼2 Ma) among Apollo samples and consequently contain only limited cosmogenic (e.g. 124,126Xe) and solar wind (SW) noble gases. Furthermore, anorthosites have negligible contributions of fissiogenic Xe isotopes because of their very low Pu and U contents. As observed in previous studies (Lightner and Marti, 1974; Leich and Niemeyer, 1975), lunar anorthosite Xe presents an isotopic composition very close to that of terrestrial atmospheric Xe, previously attributed to ;anomalous adsorption; of terrestrial Xe after sample return. The presumed atmospheric Xe contamination can only be removed by heating the samples at medium to high temperatures under vacuum, and is therefore different from common adsorption. To test this hypothesis, we monitored the adsorption of Xe onto lunar anorthositic powder using infrared reflectance spectroscopy. A clear shift in the anorthosite IR absorbance peaks is detected when comparing the IR absorbance spectra of the lunar anorthositic powder before and after exposure to a neutral Xe-rich atmosphere. This observation accounts for the chemical bonding (chemisorption) of Xe onto anorthosite, which is stronger than the common physical bonding (physisorption) and could account for the anomalous adsorption of Xe onto lunar samples. Our high precision Xe isotope analyses show slight mass fractionation patterns across 128-136Xe isotopes with systematic deficits in the heavy Xe isotopes (mostly 136Xe and marginally 134Xe) that have not previously been observed. This composition could be the result of mixing between an irreversibly adsorbed terrestrial

  5. 75 FR 12737 - Applications To Export Electric Energy; Noble Energy Marketing and Trade Corp. (United States)


    ... Applications To Export Electric Energy; Noble Energy Marketing and Trade Corp. AGENCY: Office of Electricity... applications, Noble Energy Marketing and Trade Corp. (NEMT) has applied for authority to transmit electric... Marketing and Trade Corp., 333 Ludlow Street, Suite 1230, Stamford, CT 06902. A final decision will be made...

  6. Response to selection for shell length in the noble scallop, Chlamys ...

    African Journals Online (AJOL)

    The noble scallop, Chlamys nobilis is one of the most economically important fishery and aquaculture species in the southern coast of China. In the present study, we conducted a one generation mass selection for shell length in a cultured noble scallop stock with a selection intensity of 1.732, to examine their response to ...

  7. Electrospun Polymer Nanofibers Decorated with Noble Metal Nanoparticles for Chemical Sensing


    Chen, Chen; Tang, Yongan; Vlahovic, Branislav; Yan, Fei


    The integration of different noble metal nanostructures, which exhibit desirable plasmonic and/or electrocatalytic properties, with electrospun polymer nanofibers, which display unique mechanical and thermodynamic properties, yields novel hybrid nanoscale systems of synergistic properties and functions. This review summarizes recent advances on how to incorporate noble metal nanoparticles into electrospun polymer nanofibers and illustrates how such integration paves the way towards chemical s...

  8. Noble Gas Migration Experiment to Support the Detection of Underground Nuclear Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Khris B.; Kirkham, Randy R.; Woods, Vincent T.; Haas, Derek A.; Hayes, James C.; Bowyer, Ted W.; Mendoza, Donaldo P.; Lowrey, Justin D.; Lukins, Craig D.; Suarez, Reynold; Humble, Paul H.; Ellefson, Mark D.; Ripplinger, Mike D.; Zhong, Lirong; Mitroshkov, Alexandre V.; Aalseth, Craig E.; Prinke, Amanda M.; Mace, Emily K.; McIntyre, Justin I.; Stewart, Timothy L.; Mackley, Rob D.; Milbrath, Brian D.; Emer, Dudley; Biegalski, S.


    A Noble Gas Migration Experiment (NGME) funded by the National Center for Nuclear Security and conducted at the Nevada National Security Site (NNSS) in collaboration with Lawrence Livermore national Laboratory and National Security Technology provided critical on-site inspection (OSI) information related to the detection of an underground nuclear explosion (UNE) event using noble gas signatures.

  9. Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Shaoli Zhu


    Full Text Available Noble metal, especially gold (Au and silver (Ag nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR. In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA method, and finite-difference time domain (FDTD method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL and focused ion beam (FIB are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs-potential Alzheimer's disease (AD biomarkers, and staphylococcal enterotixn B (SEB in nano-Moore per liter (nM concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

  10. Mechanics of liquids and gases

    CERN Document Server

    Loitsyanskii, L G; Jones, W P


    Mechanics of Liquids and Gases, Second Edition is a 10-chapter text that covers significant revisions concerning the dynamics of an ideal gas, a viscous liquid and a viscous gas.After an expanded introduction to the fundamental properties and methods of the mechanics of fluids, this edition goes on dealing with the kinetics and general questions of dynamics. The next chapters describe the one-dimensional pipe flow of a gas with friction, the elementary theory of the shock tube; Riemann's theory of the wave propagation of finite intensity, and the theory of plane subsonic and supersonic flows.

  11. Ultrasonic waves in classical gases (United States)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.


    The velocity and absorption coefficient for the plane sound waves in a classical gas are obtained by solving the Boltzmann kinetic equation, which describes the reaction of the single-particle distribution function to a periodic external field. Within the linear response theory, the nonperturbative dispersion equation valid for all sound frequencies is derived and solved numerically. The results are in agreement with the approximate analytical solutions found for both the frequent- and rare-collision regimes. These results are also in qualitative agreement with the experimental data for ultrasonic waves in dilute gases.

  12. High Pressure Gases in Hollow Core Photonic Crystal Fiber:A New Nonlinear Medium

    CERN Document Server

    Azhar, Mohiudeen; Chang, Wonkeun; Joly, Nicolas; Russell, Philip


    The effective Kerr nonlinearity of hollow-core kagome-style photonic crystal fiber (PCF) filled with argon gas increases over 100 times when the pressure is increased from 1 to 150 bar, reaching 15 % of that of bulk silica glass, while the zero dispersion wavelength shifts from 300 to 900 nm. The group velocity dispersion of the system is uniquely pressure-tunable over a wide range while avoiding Raman scattering : absent in noble gases and having an extremely high optical damage threshold. As a result, detailed and well controlled studies of nonlinear effects can be performed, in both normal and anomalous dispersion regimes, using only a fixed-frequency pump laser. For example, the absence of Raman scattering permits clean observation, at high powers, of the interaction between a modulational instability side-band and a soliton created dispersive wave. Excellent agreement is obtained between numerical simulations and experimental results. The system has great potential for the realisation of reconfigurable s...

  13. Intervex. A new process for desulphurisation of flue gases

    Energy Technology Data Exchange (ETDEWEB)

    Tiberg, Lars [Radscan Intervex AB, Vaesteras (Sweden); Eriksson, Mats


    A new process for flue gas desulphurisation of flue gases is presented. In a reactor, flue gases pass counter flow through a bed of granular limestone. Water is sprayed over the bed. The limestone is slowly circulated through the bed when the bed material is slowly moving downward in the reactor. Sulphur oxide from the flue gas forms calcium sulphite and sulphate in the spray water flow. A first plant for a 20 MW boiler has been operated during a long development period and now shows interesting properties and results: high degrees of reduction of sulphur, chlorides, fluorides and fly ash, the sorbent is cheap, the pressure drop is low, the yield of the limestone is 75 % and the investment cost is also low. (orig.)

  14. Therapeutic Potential of Noble Nanoparticles for Wound Repair

    Directory of Open Access Journals (Sweden)

    Timur Saliyev


    Full Text Available Introduction. Nanoparticles made of noble metals, such as gold and silver, have a great potential to be effectively employed for wound management. The nano-size of such particles provides an opportunity to enlarge the contacting area, which results in more effective anti-bacterial action and faster wound repair. It must be noted that the shape of noble nanoparticles might play a crucial role in the manifestation of their anti-microbial properties. The modern state of technology allows fabrication of the nanoparticles with the desired shape and physical properties. In order to provide efficacy and close contact with the wound, the noble nanoparticles can be incorporated into a special matrix made of a cryogel (based on polymethyl methacrylate. This combination might serve as a foundation for developing completely new types of wound dressing.Materials and methods. We have developed a few methods for synthesizing gold and silver nanoparticles of different shapes and sizes. After fabrication of metallic nanoparticles, they were characterized by using Tunneling Electron Microscopy (TEM and Malvern Zetasizer system in order to determine the average population size and consistency. The silver nanoparticles was synthesized using sodium borohydride reduction of silver nitrate. The synthesis of gold nanoparticles was conducted by using the Turkevich method.Results. We have developed a synthetic cryogel based on polyacrylamide (by cryogelation reaction at several temperatures. At the second step, we developed a method for conjugating fabricated gold and silver nanoparticles to the surface (or pores of cryogel through covalent bonds so they can provide antibacterial action within the wound. By following the developed protocol, we were able to obtain an approximate cryogel layer (1 cm thickness with embedded gold and silver nanoparticles. This conjugate was analyzed and confirmed using Scanning Electron Microscopy (SEM and TEM.Discussion. The obtained

  15. Coupled cluster calculations of mean excitation energies of the noble gas atoms He, Ne and Ar and of the H2 molecule

    DEFF Research Database (Denmark)

    Sauer, Stephan P. A.; Ul Haq, Inam; Sabin, John R.


    Using an asymmetric-Lanczos-chain algorithm for the calculation of the coupled cluster linear response functions at the CCSD and CC2 levels of approximation, we have calculated the mean excitation energies of the noble gases He, Ne and Ar, and of the hydrogen molecule H2. Convergence with respect...... by about 1%. For the two-electron systems He and H2, our CCSD results (for a Lanczos chain length equal to the full excitation space), I0 = 42:28 eV (Helium) and I0 = 19:62 eV (H2), correspond to full conguration interaction results and are therefore the exact, non-relativistic theoretical values...

  16. Collision-induced dissociation of protonated water clusters (United States)

    Berthias, F.; Buridon, V.; Abdoul-Carime, H.; Farizon, B.; Farizon, M.; Dinh, P. M.; Reinhard, P.-G.; Suraud, E.; Märk, T. D.


    Collision-induced dissociation (CID) has been studied for protonated water clusters H+(H2O)n, with n = 2-8, colliding with argon atoms at a laboratory energy of 8 keV. The experimental data have been taken with an apparatus (Device for Irradiation of Molecular Clusters, `Dispositif d'Irradiation d'Agrégats Moléculaire,' DIAM) that has been recently constructed at the Institut de Physique Nucléaire de Lyon. It includes an event-by-event mass spectrometry detection technique, COINTOF (correlated ion and neutral fragment time of flight). The latter device allows, for each collision event, to detect and identify in a correlated manner all produced neutral and charged fragments. For all the studied cluster ions, it has allowed us to identify branching ratios for the loss of i = 1 to i = n water molecules, leading to fragment ions ranging from H+(H2O)i=n-1 all the way down to the production of protons. Using a corresponding calibration technique we determine total charged fragment production cross sections for incident protonated water clusters H+(H2O)n, with n = 2-7. Observed trends for branching ratios and cross sections, and a comparison with earlier data on measured attenuation cross sections for water clusters colliding with other noble gases (He and Xe), give insight into the underlying dissociation mechanisms.

  17. INGAS: Iranian Noble Gas Analyzing System for radioxenon measurement (United States)

    Doost-Mohammadi, V.; Afarideh, H.; Etaati, G. R.; Safari, M. J.; Rouhi, H.


    In this article, Iranian Noble Gas Analyzing System (INGAS) will be introduced. This system is based on beta-gamma coincidence technique and consists of a well-type NaI(Tl) as gamma or X radiation detector and a cylindrical plastic scintillator to detect beta or conversion electron. Standard NIM modules were utilized to detect coincidence events of detectors. Both the beta and gamma detectors were appropriately calibrated. The efficiency curve of gamma detector for volume geometry was obtained by comparing the results of gamma point sources measurements and simulations of GATE V7.0 Monte Carlo code. The performance of detection system was checked by injection of 222Rn and 131mXe gaseous source in the detection cell. The minimum detectable activity of the system for 133Xe is 1.240±0.024 mBq for 24 h measurement time.

  18. Life at the College of Nobles Maidens of Toledo

    Directory of Open Access Journals (Sweden)

    Ángel Santos Vaquero


    Full Text Available The College of Noble Maidens of Toledo was founded by Cardinal Silíceo in 1551, designed to train women as holy and Christian wives and educated housewives. As would be admitted girls who could prove their ancestry free of impure blood. When they married would receive a dowry. Over time the institution was made many visits that were trying to bring order to the relaxation of discipline and desmadres produced both in administrative matters such as economic and internal order. Finally on July 20, 1988 was agreed between the Archbishop of Toledo and National Heritage. For him the Statute of Real Compatronato were modified and agreed to convert the institution into a female dorm.

  19. Obtaining memristor elements based on non-noble materials

    Directory of Open Access Journals (Sweden)

    Troyan Pavel


    Full Text Available This study is aimed at creating memristor elements based on TiO2/TiOx layers with electrodes that do not contain noble and rare-earth metals, by vacuum deposition method. The characteristics of these elements analyzed by voltammetric methods show that the appearance of an N-type region of negative differential resistance on the current–voltage curve can be caused only by metal electrodes whose vacuum work function exceeds that of TiO2. The appearance of the N-type region on the current–voltage curve of a memristor element is possible only after electrically assisted vacuum forming. Mo–TiO2/TiOx–Ni/Cu structures, for which the ILR/IHR ratio reaches two orders of magnitude at a voltage of less than 4 V, have the most stable parameters.

  20. Surface entropy of liquid transition and noble metals (United States)

    Gosh, R. C.; Das, Ramprosad; Sen, Sumon C.; Bhuiyan, G. M.


    Surface entropy of liquid transition and noble metals has been investigated using an expression obtained from the hard-sphere (HS) theory of liquid. The expression is developed from the Mayer's extended surface tension formula [Journal of Non-Crystalline Solids 380 (2013) 42-47]. For interionic interaction in metals, Brettonet-Silbert (BS) pseudopotentials and embedded atom method (EAM) potentials have been used. The liquid structure is described by the variational modified hypernetted chain (VMHNC) theory. The essential ingredient of the expression is the temperature dependent effective HS diameter (or packing fraction), which is calculated from the aforementioned potentials together with the VMHNC theory. The obtained results for the surface entropy using the effective HS diameter are found to be good in agreement with the available experimental as well as other theoretical values.

  1. Interaction between Nafion ionomer and noble metal catalyst for PEMFCs

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    The implement of polymer impregnation in electrode structure (catalyst layer) decreasing the noble metal catalyst loading by a factor of ten , , is one of the essential mile stones in the evolution of Proton Exchange Membrane Fuel Cells’ development among the application of catalyst support...... and electrode deposition etc. In fuel cell reactions, both electrons and protons are involved. Impregnation of Nafion ionomer in catalyst layer effectively increases the proton-electron contact, enlarge the reaction zone, extend the reaction from the surface to the entire electrode. Therefore, the entire...... catalyst layer conducts both electrons and protons so that catalyst utilization in the layer is improved dramatically. The catalyst layer will in turn generate and sustain a higher current density. One of the generally adapted methods to impregnate Nafion into the catalyst layer is to mix the catalysts...

  2. Studies on PEM fuel cell noble metal catalyst dissolution

    DEFF Research Database (Denmark)

    Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.


    A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

  3. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

    Directory of Open Access Journals (Sweden)

    Aminul Islam

    Full Text Available A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3 are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

  4. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal. (United States)

    Islam, Aminul; Teo, Siow Hwa; Rahman, M Aminur; Taufiq-Yap, Yun Hin


    A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

  5. Noble metal ionic sites for catalytic hydrogen combustion: spectroscopic insights. (United States)

    Deshpande, Parag A; Madras, Giridhar


    A catalytic hydrogen combustion reaction was carried out over noble metal catalysts substituted in ZrO(2) and TiO(2) in ionic form. The catalysts were synthesized by the solution combustion technique. The compounds showed high activity and CO tolerance for the reaction. The activity of Pd and Pt ion substituted TiO(2) was comparable and was higher than Pd and Pt ion substituted ZrO(2). The mechanisms of the reaction over the two supports were proposed by making use of the X-ray photoelectron spectroscopy and FT infrared spectroscopic observations. The reaction over ZrO(2) supported catalysts was proposed to take place by the utilization of the surface hydroxyl groups while the reaction over TiO(2) supported catalysts was hypothesized to be a hybrid mechanism utilizing surface hydroxyl groups and the lattice oxygen.

  6. Concept of Heat Recovery from Exhaust Gases (United States)

    Bukowska, Maria; Nowak, Krzysztof; Proszak-Miąsik, Danuta; Rabczak, Sławomir


    The theme of the article is to determine the possibility of waste heat recovery and use it to prepare hot water. The scope includes a description of the existing sample of coal-fired boiler plant, the analysis of working condition and heat recovery proposals. For this purpose, a series of calculations necessary to identify the energy effect of exhaust temperature decreasing and transferring recovery heat to hot water processing. Heat recover solutions from the exhaust gases channel between boiler and chimney section were proposed. Estimation for the cost-effectiveness of such a solution was made. All calculations and analysis were performed for typical Polish conditions, for coal-fired boiler plant. Typicality of this solution is manifested by the volatility of the load during the year, due to distribution of heat for heating and hot water, determining the load variation during the day. Analysed system of three boilers in case of load variation allows to operational flexibility and adaptation of the boilers load to the current heat demand. This adaptation requires changes in the operating conditions of boilers and in particular assurance of properly conditions for the combustion of fuel. These conditions have an impact on the existing thermal loss and the overall efficiency of the boiler plant. On the boiler plant efficiency affects particularly exhaust gas temperature and the excess air factor. Increasing the efficiency of boilers plant is possible to reach by following actions: limiting the excess air factor in coal combustion process in boilers and using an additional heat exchanger in the exhaust gas channel outside of boilers (economizer) intended to preheat the hot water.

  7. Comparison of natural gases accumulated in Oligocene strata with hydrous pyrolysis gases from Menilite Shales of the Polish Outer Carpathians (United States)

    Kotarba, M.J.; Curtis, John B.; Lewan, M.D.


    This study examined the molecular and isotopic compositions of gases generated from different kerogen types (i.e., Types I/II, II, IIS and III) in Menilite Shales by sequential hydrous pyrolysis experiments. The experiments were designed to simulate gas generation from source rocks at pre-oil-cracking thermal maturities. Initially, rock samples were heated in the presence of liquid water at 330 ??C for 72 h to simulate early gas generation dominated by the overall reaction of kerogen decomposition to bitumen. Generated gas and oil were quantitatively collected at the completion of the experiments and the reactor with its rock and water was resealed and heated at 355 ??C for 72 h. This condition simulates late petroleum generation in which the dominant overall reaction is bitumen decomposition to oil. This final heating equates to a cumulative thermal maturity of 1.6% Rr, which represents pre-oil-cracking conditions. In addition to the generated gases from these two experiments being characterized individually, they are also summed to characterize a cumulative gas product. These results are compared with natural gases produced from sandstone reservoirs within or directly overlying the Menilite Shales. The experimentally generated gases show no molecular compositions that are distinct for the different kerogen types, but on a total organic carbon (TOC) basis, oil prone kerogens (i.e., Types I/II, II and IIS) generate more hydrocarbon gas than gas prone Type III kerogen. Although the proportionality of methane to ethane in the experimental gases is lower than that observed in the natural gases, the proportionality of ethane to propane and i-butane to n-butane are similar to those observed for the natural gases. ??13C values of the experimentally generated methane, ethane and propane show distinctions among the kerogen types. This distinction is related to the ??13C of the original kerogen, with 13C enriched kerogen generating more 13C enriched hydrocarbon gases than

  8. Cooling Atomic Gases With Disorder (United States)

    Paiva, Thereza; Khatami, Ehsan; Yang, Shuxiang; Rousseau, Valéry; Jarrell, Mark; Moreno, Juana; Hulet, Randall G.; Scalettar, Richard T.


    Cold atomic gases have proven capable of emulating a number of fundamental condensed matter phenomena including Bose-Einstein condensation, the Mott transition, Fulde-Ferrell-Larkin-Ovchinnikov pairing, and the quantum Hall effect. Cooling to a low enough temperature to explore magnetism and exotic superconductivity in lattices of fermionic atoms remains a challenge. We propose a method to produce a low temperature gas by preparing it in a disordered potential and following a constant entropy trajectory to deliver the gas into a nondisordered state which exhibits these incompletely understood phases. We show, using quantum Monte Carlo simulations, that we can approach the Néel temperature of the three-dimensional Hubbard model for experimentally achievable parameters. Recent experimental estimates suggest the randomness required lies in a regime where atom transport and equilibration are still robust.

  9. Noble Metal Arsenides and Gold Inclusions in Northwest Africa 8186 (United States)

    Srinivasan, P.; McCubbin, F. M.; Rahman, Z.; Keller, L. P.; Agee, C. B.


    CK carbonaceous chondrites are a highly thermally altered group of carbonaceous chondrites, experiencing temperatures ranging between approximately 576-867 degrees Centigrade. Additionally, the mineralogy of the CK chondrites record the highest overall oxygen fugacity of all chondrites, above the fayalite-magnetite-quartz (FMQ) buffer. Me-tallic Fe-Ni is extremely rare in CK chondrites, but magnetite and Fe,Ni sulfides are commonly observed. Noble metal-rich inclusions have previously been found in some magnetite and sulfide grains. These arsenides, tellurides, and sulfides, which contain varying amounts of Pt, Ru, Os, Te, As, Ir, and S, are thought to form either by condensation from a solar gas, or by exsolution during metamorphism on the chondritic parent body. Northwest Africa (NWA) 8186 is a highly metamorphosed CK chondrite. This meteorite is predominately composed of NiO-rich forsteritic olivine (Fo65), with lesser amounts of plagioclase (An52), augite (Fs11Wo49), magnetite (with exsolved titanomagnetite, hercynite, and titanohematite), monosulfide solid solution (with exsolved pentlandite), and the phosphate minerals Cl-apatite and merrillite. This meteorite contains coarse-grained, homogeneous silicates, and has 120-degree triple junctions between mineral phases, which indicates a high degree of thermal metamorphism. The presence of NiO-rich olivine, oxides phases all bearing Fe3 plus, and the absence of metal, are consistent with an oxygen fugacity above the FMQ buffer. We also observed noble metal-rich phases within sulfide grains in NWA 8186, which are the primary focus of the present study.

  10. Explorative analysis of microbes, colloids and gases

    Energy Technology Data Exchange (ETDEWEB)

    Hallbeck, Lotta; Pedersen, Karsten (Microbial Analytics Sweden AB, Goeteborg (Sweden))


    The overall objectives of the hydrogeochemical description for Forsmark are to establish a detailed understanding of the hydrogeochemical conditions at the site and to develop models that fulfil the needs identified by the safety assessment groups during the site investigation phase. Issues of concern to safety assessment are radionuclide transport and technical barrier behaviour, both of which are dependent on the chemistry of groundwater and pore water and their evolution with time. In this report, part of the final hydrogeochemical evaluation work of the site investigation at the Forsmark site, is presented. The work was conducted by SKB's hydrogeochemical project group, ChemNet, which consists of independent consultants and Univ. researchers with expertise in geochemistry, hydrochemistry, hydrogeochemistry, microbiology, geomicrobiology, analytical chemistry etc. The resulting site descriptive model version, mainly based on 2.2 data and complementary 2.3 data, was carried out during September 2006 to December 2007. This report focuses on microbiology, colloids and gases: - Microbes (Chapter 1): Several methods must be used to characterize active microbial communities in groundwater. Microbial parameters of interest are the total number of cells (TNC) and the presence of various metabolic groups of microorganisms. Different microbial groups influence the environment in different ways, depending on what metabolic group is dominant. Typically, the following redox couples are utilized by bacteria in granitic groundwater: H{sub 2}O/O{sub 2}, NO{sub 3}-/N{sub 2}, Mn2+/Mn(IV), Fe2+/Fe(III), S2-/SO{sub 4}2-, CH{sub 4}/CO{sub 2}, CH{sub 3}COOH/CO{sub 2}, and H{sub 2}/H+. The data will indicate the activity of specific microbial populations at particular sites and how they may affect the geochemistry. - Colloids (Chapter 2): Particles in the size range from 1 to 1x10-3 mum are regarded as colloids. Their small size prohibits them from settling, which gives them the

  11. Assessing the importance of food for improving noble crayfish culture conditions

    Directory of Open Access Journals (Sweden)

    Rusch J.C.


    Full Text Available Captive breeding and crayfish culture are considered important measures in species protection activities. Thus, knowledge on optimal feeding of crayfish in captivity is needed in order to secure minimal mortality and prevent detrimental effects to health. To optimize conditions of crayfish prior to subsequent stocking, feeding trials were conducted with the aim of investigating the connection between food intake, food preference and temperature under near natural conditions. During a five-month period, noble crayfish were fed on fish, carrots, algae and chironomid-larvae according to a pre-defined rotation system, whereby the ambient water temperature ranged from 5 °C to 13 °C, following the natural temperature regime. The results of these feeding trials demonstrate a direct correlation between rising temperature and increasing food intake for water temperatures exceeding 8 °C. Food intake is further influenced by the variety of food items available at any one time. The results also confirm that Astacus astacus has a strong preference for fish and that alternation of food types has an impact on consumption. Our results prompt the following recommendations for optimized feeding conditions of crayfish in captivity prior to their release: (1 a balanced diet containing not only plant tissue but also a significant proportion of animal tissue and (2 the amount of available food must be adjusted according to the carapace length of the crayfish.

  12. Noble metal nanoparticles on quartz supports as SERS substrates excited by a diode laser system for SERDS (United States)

    Ossig, Robert; Kwon, Yong-Hyok; Kronfeldt, Heinz-Detlef; Träger, Frank; Hubenthal, Frank


    In this contribution we present surface enhanced Raman scattering (SERS) measurements of pyrene as a function of the surface plasmon resonance position of noble metal nanoparticle ensembles, which served as SERS substrates. The noble metal nanoparticle ensembles were prepared under ultrahigh vacuum (UHV) conditions by Volmer-Weber growth on quartz substrates. For the SERS measurements, the substrates were mounted in a flow-through cell as part of the optical Raman set-up. A diode laser microsystem with an emission wavelength of 488 nm was used. The system generates two slightly different emission wavelengths (Δλ ~ 0.3 nm) with a spectral width of ~ 10 pm and an optical power of ~ 10 mW. With this set-up SERS as well as shifted excitation Raman difference spectroscopy (SERDS) can be carried out. For trace analysis of pyrene in water SERS/SERDS experiments were accomplished as a function of molecule concentration and spectral position of the plasmon resonance. The best results with a limit of detection of 2 nmol of pyrene were obtained with a nanoparticle ensemble with a plasmon resonance in the vicinity of the excitation wavelength of λ = 488 nm. If the plasmon resonance frequency is slightly off-resonance the detection limit is significantly lower. The latter results are discussed in more detail and we will demonstrate that the morphology and the optical properties of the SERS substrates crucially influence the LOD.

  13. 40 CFR 1065.750 - Analytical gases. (United States)


    ... ± 3.0% of the NIST-accepted value or other similar standards we approve, and meet the stability..., such as a compressed-gas cylinder. (d) To maintain stability and purity of gas standards, use good..., span, and calibration gases. For example, it may be necessary to store bottles of condensable gases in...

  14. Properties and Bibliography of GaSe (United States)


    Brahim-Otsmane 1993) and (Fargues 1993). Growth of Fullerene thin films on a GaSe substrate is covered by (Sakurai 1993). There is some literature on the...and GaSe samples." Experimentelle Technik der Physik. 37 173-185 Stadnik, V. A. (1988). "Optical bistability, the pulsation effect, and 95 GaS. Page 55

  15. Greenhouse Gases Concentrations in the Atmosphere Along ...

    African Journals Online (AJOL)

    This study investigated effect of vehicular emission on greenhouse gases concentrations along selected roads of different traffic densities in Abeokuta, Ogun State, Nigeria. Nine roads comprised highway, commercial and residential were selected. Greenhouse Gases (GHGs) were determined from both sides of the roads by ...

  16. 40 CFR 90.312 - Analytical gases. (United States)


    ... calibration gas must not exceed five percent of the NO content); CO2 and purified nitrogen. Note: For the HFID... accuracy of the mixing device must be such that the concentration of the diluted gases may be determined to... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Analytical gases. 90.312 Section 90...

  17. Study on the utilization of the energy produced by the exhaust gases and the cooling water of a internal combustion engine; Estudo do aproveitamento da energia obtida pelos gases de escapamento e pela agua de resfriamento de um motor de combustao interna

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Andre Luiz dos; Arroyo, Narciso Angel Ramos [Santa Catarina Univ., Florianopolis (Brazil). Dept. de Engenharia Mecanica. Lab. de Combustao e Motores Termicos]. E-mail:;


    This work is about heat balance of an automotive internal combustion engine of 4 cylinders, using ethylic alcohol, and utilize the energy obtained in the exhaust gas and the water cooling system. This paper show an theoretical - experimental model for use this energy in an absorption refrigeration system using the work fluid water and Li Br. In this paper are analyzed engines charges of 30%, 50% and 100%. The results shows that for this charges and for any speed of the engines, the energy obtained in the evaporator are significant. (author)

  18. Process for the removal of acid forming gases from exhaust gases and production of phosphoric acid (United States)

    Chang, Shih-Ger; Liu, David K.


    Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorous preferably in a wet scrubber. The addition of yellow phosphorous in the system induces the production of O.sub.3 which subsequently oxidizes NO to NO.sub.2. The resulting NO.sub.2 dissolves readily and can be reduced to form ammonium ions by dissolved SO.sub.2 under appropriate conditions. In a 20 acfm system, yellow phosphorous is oxidized to yield P.sub.2 O.sub.5 which picks up water to form H.sub.3 PO.sub.4 mists and can be collected as a valuable product. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about C. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, better than 90% of SO.sub.2 and NO in simulated flue gas can be removed. Stoichiometric ratios (P/NO) ranging between 0.6 and 1.5 were obtained.

  19. Exploring methods for compositional and particle size analysis of noble metal nanoparticles in Daphnia manga

    NARCIS (Netherlands)

    Krystek, P.W.; Brandsma, S.H.; Leonards, P.E.G.; de Boer, J.


    The identification and quantification of the bioaccumulation of noble metal engineered nanoparticles (ENPs) by aquatic organisms is of great relevance to understand the exposure and potential toxicity mechanisms of nanoscale materials. Four analytical scenarios were investigated in relation to

  20. CsI-THGEM gaseous photomultipliers for RICH and noble-liquid detectors

    CERN Document Server

    Breskin, A; Cortesi, M; Budnik, R; Chechik, R; Duval, S; Thers, D; Coimbra, A E.C; dos Santos, J M.F; Lopes, J A.M; Azevedo, C D.R; Veloso, J F.C A


    The properties of UV-photon imaging detectors consisting of CsI-coated THGEM electron multipliers are summarized. New results related to detection of Cherenkov light (RICH) and scintillation photons in noble liquid are presented.