WorldWideScience

Sample records for br isotopes close

  1. Isotope fractionation in aqua-gas systems: Cl(2)-HCl-Cl(-), Br(2)-HBr-Br(-) and H(2)S-S(2-).

    Science.gov (United States)

    Czarnacki, Maciej; Hałas, Stanisław

    2012-01-01

    We report calculated values of isotope fractionation factors between chlorine, bromine and sulphide hydrated anions and respective gaseous compounds: hydrogen chloride, hydrogen bromide, molecular chlorine and bromine and hydrogen sulphide. For the calculation of the reduced partition function ratios (β-factors) of hydrated Cl(-), Br(-) and S(2-) anions, we used a model of a cluster composed of the considered ion surrounded by two shells of H(2)O molecules. Only the electrostatic interaction between ion and water molecules treated as electric dipoles was taken into account. The β-factors for the gaseous compounds (HCl, Cl(2), HBr, Br(2) and H(2)S) were calculated from vibrational frequencies reported by Urey and Greiff [Isotopic Exchange Equilibria, J. Am. Chem. Soc. 57, 321 (1935)] and Schauble et al. [Theoretical Estimates Equilibrium Chlorine-Isotope Fractionation, Geochim. Cosmochim. Acta 67, 3267 (2003)]. Low-temperature isotope fractionation between chlorine-hydrated anion and hydrogen chloride attains 1.55-1.68‰ (this work), which is in good agreement with experimental data (1.4-1.8‰) [Z.D. Sharp, J.D. Barnes, T.P. Fischer and M. Halick, An Experimental Determination of Chlorine Isotope Fractionation in Acid Systems and Applications to Volcanic Fumaroles, Geochim. Cosmochim. Acta 74, 264 (2010)]. The predicted isotope fractionations for hydrated bromine and HBr, Br(2) gases are very small, 1000 ln α, do not exceed 0.8‰; thus, the expected variations of bromine isotope composition in aqua-gas systems will require enhanced precision for their detection. In contrast, the sulphur isotope fractionation between H(2)S( gas ) and S(2-) attains 6.0‰ at room temperature and drops nearly linearly to 3.1‰ at 350°C.

  2. Modeling study of vibrational photochemical isotope enrichment. [HBr + Cl/sub 2/; HCl + Br/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Badcock, C.C.; Hwang, W.C.; Kalsch, J.F.

    1978-09-29

    Chemical kinetic modeling studies of vibrational-photochemical isotope enrichment have been performed on two systems: Model (I), H/sup 79/Br(H/sup 81/Br) + Cl/sub 2/ and, Model (II), H/sup 37/Cl(H/sup 35/Cl) + Br. Pulsed laser excitation was modeled to the first excited vibrational level of H/sup 79/Br in Model I and the first and second excited vibrational levels of both HCl isotopes in Model II. These are prototype systems of exoergic (Model I) and endoergic (Model II) reactions. The effects on enrichment of varying the external parameters (pressure, laser intensity) and the internal parameters (rate constants for V-V exchange and excited-state reactions) were examined. Studies of these prototype systems indicate that a favorable reaction for enrichment, with isotopically-specific excitation and a significantly accelerated vibrationally-excited-state reaction should have the following properties: the reaction from v = 0 should be only moderately exoergic, and the most favorable coreactant should be a polyatomic species, such as alkyl radical. Direct excitation of the reacting vibrational level is at least an order of magnitude more favorable for enrichment than is population by energy transfer. Enrichment of the minor isotope by these processes is more effective than is major isotope enrichment. Within limits, increased laser intensity is beneficial. However, for sequential excitation of a second vibrational level, major isotope enrichment can be diminished by high populations of the first vibrational level.

  3. Influence of irrigation practices on arsenic mobilization: Evidence from isotope composition and Cl/Br ratios in groundwater from Datong Basin, northern China

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Li, Junxia; Li, Mengdi

    2012-03-01

    SummaryEnvironment isotopes (δ18O and δ2H) and Cl/Br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in Datong Basin. The arsenic concentrations of groundwater samples ranged from 0.4 to 434.9 μg/L with the average of 51.2 μg/L, which exceeded China's drinking water standard (10 μg/L). All the groundwater samples are plotted on or close to the meteoric water line of the δ18O vs. δ2H plot, indicating their meteoric origin. The relationship between δ18O values and Cl/Br ratios and Cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area. The observed non-linearity in the trend between δ18O and arsenic concentration is due to combined effects of mixing and leaching. The similarity of the trend in Cl/Br ratios and δ18O values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system. Moreover, the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system, which in turn promotes the mobilization of arsenic. Therefore, groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area.

  4. Using Halogens (Cl, Br, F, I) and Stable Isotopes of Water (δ18O, δ2H) to Trace Hydrological and Biogeochemical Processes in Prairie Wetlands

    Science.gov (United States)

    Levy, Z. F.; Lu, Z.; Mills, C. T.; Goldhaber, M. B.; Rosenberry, D. O.; Mushet, D.; Siegel, D. I.; Fiorentino, A. J., II; Gade, M.; Spradlin, J.

    2014-12-01

    Prairie pothole wetlands are ubiquitous features of the Great Plains of North America, and important habitat for amphibians and migratory birds. The salinity of proximal wetlands varies highly due to groundwater-glacial till interactions, which influence wetland biota and associated ecosystem functions. Here we use halogens and stable isotopes of water to fingerprint hydrological and biogeochemical controls on salt cycling in a prairie wetland complex. We surveyed surface, well, and pore waters from a groundwater recharge wetland (T8) and more saline closed (P1) and open (P8) basin discharge wetlands in the Cottonwood Lake Study Area (ND) in August/October 2013 and May 2014. Halogen concentrations varied over a broad range throughout the study area (Cl = 2.2 to 170 mg/L, Br = 13 to 2000 μg/L, F = < 30 (MDL) to 740 μg/L, I = 1 to 538 μg/L). The Cl/Br molar ratios were higher (171 to 574) at the recharge wetland, indicating meteoric sources, and had a tighter and lower range (33 to 320) at the down-gradient sites. The Cl/I molar ratios of waters throughout the site had a wide range (32 to 26,000). Lowest values occurred at the upgradient shore of P1 (32 to 43) due to low Cl concentrations and the center of P1 (196 to 213) where pore water of weathered till underlying 1.2 m of organic-rich sediment and silty clay soil is enriched in I to ~500 µg/L. Stable isotopes of water showed that evaporation-enriched pond water (δ18O = -9.5 to -2.71 ‰) mixes with shallow groundwater in the top 0.6 m of fringing wetland soils and 1.2 m of the substrate in the center of P1. Our results suggest endogenous sources for Br and I within the prairie landscape that may be controlled by biological mechanisms or weathering of shale from glacial till.

  5. Neon Isotope Fractionation in Ice Cores at Close-Off Depth

    Science.gov (United States)

    Liang, C.; Severinghaus, J. P.

    2015-12-01

    Analyzing trapped air bubbles in glacial ice is a well-established and useful method to reconstruct past atmospheric gas concentrations. However, trapped gas composition can be affected by fractionation during the closure of the air bubbles, complicating the reconstruction. Gases such as dioxygen (O2) and dihydrogen (H2) are known to leak out of the bubbles by permeation through the ice lattice at the close-off depth,where firn turns into ice. This process also can cause isotope fractionation, which obscures the past atmospheric isotope ratios in air bubbles in glacial ice. In order to establish the most accurate measurements of past atmospheric content, we need very detailed understanding of the permeation leakage mechanism in order to establish possible corrections. In this study, we propose the use of neon stable isotopes (neon-22 and neon-20) to place constraints on the mechanism of permeation leakage. Neon isotopes are an ideal system to explore because neon has a constant atmospheric isotope ratio, and thus only is affected by close-off fractionation. Neon permeation occurs via velocity-dependent hopping between sites within the ice lattice, because the neon atom is smaller than the critical size (3.6 Å) of the opening in the lattice. Theory predicts that neon isotope fractionation will occur due to the lower velocity of the heavier isotope, but this has never been experimentally verified and the theory is unable to quantitatively predict the magnitude of the fractionation. We will present the first results of high-precision neon isotope (22Ne/20Ne) measurements made in air pumped from the firm-to-ice transition in the Greenland Ice Sheet, where actively closing air bubbles drive permeation leakage. By measuring this natural neon isotope fractionation, we hope to learn about the mass dependence of the leakage mechanism and develop a more quantitative theory that is generalizable to biogeochemically- and climatically-active gases.

  6. Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

    Science.gov (United States)

    Li, Junxia; Wang, Yanxin; Xie, Xianjun

    2016-02-15

    In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. Copyright © 2015. Published by Elsevier B.V.

  7. Closed system oxygen isotope redistribution in igneous CAIs upon spinel dissolution

    Science.gov (United States)

    Aléon, Jérôme

    2018-01-01

    In several Calcium-Aluminum-rich Inclusions (CAIs) from the CV3 chondrites Allende and Efremovka, representative of the most common igneous CAI types (type A, type B and Fractionated with Unknown Nuclear isotopic anomalies, FUN), the relationship between 16O-excesses and TiO2 content in pyroxene indicates that the latter commonly begins to crystallize with a near-terrestrial 16O-poor composition and becomes 16O-enriched during crystallization, reaching a near-solar composition. Mass balance calculations were performed to investigate the contribution of spinel to this 16O-enrichment. It is found that a back-reaction of early-crystallized 16O-rich spinel with a silicate partial melt having undergone a 16O-depletion is consistent with the O isotopic evolution of CAI minerals during magmatic crystallization. Dissolution of spinel explains the O isotopic composition (16O-excess and extent of mass fractionation) of pyroxene as well as that of primary anorthite/dmisteinbergite and possibly that of the last melilite crystallizing immediately before pyroxene. It requires that igneous CAIs behaved as closed-systems relative to oxygen from nebular gas during a significant fraction of their cooling history, contrary to the common assumption that CAI partial melts constantly equilibrated with gas. The mineralogical control on O isotopes in igneous CAIs is thus simply explained by a single 16O-depletion during magmatic crystallization. This 16O-depletion occurred in an early stage of the thermal history, after the crystallization of spinel, i.e. in the temperature range for melilite crystallization/partial melting and did not require multiple, complex or late isotope exchange. More experimental work is however required to deduce the protoplanetary disk conditions associated with this 16O-depletion.

  8. Precision mass measurements of Cd-127125 isotopes and isomers approaching the N =82 closed shell

    Science.gov (United States)

    Lascar, D.; Klawitter, R.; Babcock, C.; Leistenschneider, E.; Stroberg, S. R.; Barquest, B. R.; Finlay, A.; Foster, M.; Gallant, A. T.; Hunt, P.; Kelly, J.; Kootte, B.; Lan, Y.; Paul, S. F.; Phan, M. L.; Reiter, M. P.; Schultz, B.; Short, D.; Simonis, J.; Andreoiu, C.; Brodeur, M.; Dillmann, I.; Gwinner, G.; Holt, J. D.; Kwiatkowski, A. A.; Leach, K. G.; Dilling, J.

    2017-10-01

    We present the results of precision mass measurements of neutron-rich cadmium isotopes. These nuclei approach the N =82 closed neutron shell and are important to nuclear structure as they lie near doubly magic 132Sn on the chart of nuclides. Of particular note is the clear identification of the ground-state mass in 127Cd along with the isomeric state. We show that the ground state identified in a previous mass measurement which dominates the mass value in the Atomic Mass Evaluation is an isomeric state. In addition to Cd/m127, we present other cadmium masses measured (Cd/m125 and 126Cd) in a recent TITAN experiment at TRIUMF. Finally, we compare our measurements to new ab initio shell-model calculations and comment on the state of the field in the N =82 region.

  9. Evaluation of isotopic composition of fast reactor core in closed nuclear fuel cycle

    Science.gov (United States)

    Tikhomirov, Georgy; Ternovykh, Mikhail; Saldikov, Ivan; Fomichenko, Peter; Gerasimov, Alexander

    2017-09-01

    The strategy of the development of nuclear power in Russia provides for use of fast power reactors in closed nuclear fuel cycle. The PRORYV (i.e. «Breakthrough» in Russian) project is currently under development. Within the framework of this project, fast reactors BN-1200 and BREST-OD-300 should be built to, inter alia, demonstrate possibility of the closed nuclear fuel cycle technologies with plutonium as a main source of energy. Russia has a large inventory of plutonium which was accumulated in the result of reprocessing of spent fuel of thermal power reactors and conversion of nuclear weapons. This kind of plutonium will be used for development of initial fuel assemblies for fast reactors. The closed nuclear fuel cycle concept of the PRORYV assumes self-supplied mode of operation with fuel regeneration by neutron capture reaction in non-enriched uranium, which is used as a raw material. Operating modes of reactors and its characteristics should be chosen so as to provide the self-sufficient mode by using of fissile isotopes while refueling by depleted uranium and to support this state during the entire period of reactor operation. Thus, the actual issue is modeling fuel handling processes. To solve these problems, the code REPRORYV (Recycle for PRORYV) has been developed. It simulates nuclide streams in non-reactor stages of the closed fuel cycle. At the same time various verified codes can be used to evaluate in-core characteristics of a reactor. By using this approach various options for nuclide streams and assess the impact of different plutonium content in the fuel, fuel processing conditions, losses during fuel processing, as well as the impact of initial uncertainties on neutron-physical characteristics of reactor are considered in this study.

  10. Methane Emissions from Landfill: Isotopic Evidence for Low Percentage of Oxidation from Gas Wells, Active and Closed Cells

    Science.gov (United States)

    Lowry, David; Fisher, Rebecca; Zazzeri, Giulia; al-Shalaan, Aalia; France, James; Lanoisellé, Mathias; Nisbet, Euan

    2017-04-01

    Large landfill sites remain a significant source of methane emissions in developed and developing countries, with a global estimated flux of 29 Tg / yr in the EDGAR 2008 database. This is significantly lower than 20 years ago due to the introduction of gas extraction systems, but active cells still emit significant amounts of methane before the gas is ready for extraction. Historically the methane was either passively oxidized through topsoil layers or flared. Oxidation is still the primary method of methane removal in many countries, and covered, remediated cells across the world continue to emit small quantities of methane. The isotopic signatures of methane from landfill gas wells, and that emitted from active and closed cells have been characterized for more than 20 UK landfills since 2011, with more recent work in Kuwait and Hong Kong. Since 2013 the emission plumes have been identified by a mobile measurement system (Zazzeri et al., 2015). Emissions in all 3 countries have a characteristic δ13C signature of -58 ± 3 ‰ dominated by emissions from the active cells, despite the hot, dry conditions of Kuwait and the hot, humid conditions of Hong Kong. Gas well samples define a similar range. Surface emissions from closed cells and closed landfills are mostly in the range -56 to -52 ‰Ṫhese are much more depleted values than those observed in the 1990s (up to -35 ) when soil oxidation was the dominant mechanism of methane removal. Calculations using isotopic signatures of the amount of methane oxidised in these closed areas before emission to atmosphere range from 5 to 15%, but average less than 10%, and are too small to calculate from the high-emitting active cells. Compared to other major methane sources, landfills have the most consistent isotopic signature globally, and are distinct from the more 13C-enriched natural gas, combustion and biomass burning sources. Zazzeri, G. et al. (2015) Plume mapping and isotopic characterization of anthropogenic methane

  11. Isotopic Differences between Forage Consumed by a Large Herbivore in Open, Closed, and Coastal Habitats: New Evidence from a Boreal Study System.

    Directory of Open Access Journals (Sweden)

    Marie-Andrée Giroux

    Full Text Available Documenting habitat-related patterns in foraging behaviour at the individual level and over large temporal scales remains challenging for large herbivores. Stable isotope analysis could represent a valuable tool to quantify habitat-related foraging behaviour at the scale of individuals and over large temporal scales in forest dwelling large herbivores living in coastal environments, because the carbon (δ13C or nitrogen (δ15N isotopic signatures of forage can differ between open and closed habitats or between terrestrial and littoral forage, respectively. Here, we examined if we could detect isotopic differences between the different assemblages of forage taxa consumed by white-tailed deer that can be found in open, closed, supralittoral, and littoral habitats. We showed that δ13C of assemblages of forage taxa were 3.0 ‰ lower in closed than in open habitats, while δ15N were 2.0 ‰ and 7.4 ‰ higher in supralittoral and littoral habitats, respectively, than in terrestrial habitats. Stable isotope analysis may represent an additional technique for ecologists interested in quantifiying the consumption of terrestrial vs. marine autotrophs. Yet, given the relative isotopic proximity and the overlap between forage from open, closed, and supralittoral habitats, the next step would be to determine the potential to estimate their contribution to herbivore diet.

  12. Catalytic recombination of dissociation products with Pt/SnO2 for rare and common isotope long-life, closed-cycle CO2 lasers

    Science.gov (United States)

    Brown, Kenneth G.; Sidney, B. D.; Schryer, D. R.; Upchurch, B. T.; Miller, I. M.

    1986-01-01

    This paper reports results on recombination of pulsed CO2 laser dissociation products with Pt/SnO2 catalysts, and supporting studies in a surrogate laboratory catalyst reactor. The closed-cycle, pulsed CO2 laser has been continuously operated for one million pulses with an overall power degradation of less than 5 percent by flowing the laser gas mixture through a 2-percent Pt/SnO2 catalyst bed. In the surrogate laboratory reactor, experiments have been conducted to determine isotopic exchange with the catalyst when using rare-isotope gases. The effects of catalyst pretreatment, sample weight, composition, and temperature on catalyst efficiency have also been determined.

  13. Simulation of the water and isotopic balance of a closed tropical lake at a daily time step (Lake Ihotry, South-West of Madagascar)

    OpenAIRE

    Vallet Coulomb, C.; Gasse, F; Robison, L.; Ferry, Luc

    2006-01-01

    Lake Ihotry is a closed lake where evaporation constitute 99% of water outputs, and where the seasonal isotopic evaporative enrichment is important (from delta O-18=-3 parts per thousand to +6 parts per thousand and from delta H-2=-20 parts per thousand to +30 parts per thousand). For a two-year measurement period, a dynamic model of lake water level leads to an accurate determination of the water balance at a daily time step. An isotopic balance model (6180 and 62 H), including the Craig and...

  14. Toward Closing the Water Cycle over the ARM/CART Region: Implementation of Stable Water Isotope Physics in MM5

    Science.gov (United States)

    Kemball-Cook, S. R.; Miller, N. L.; DePaolo, D. J.

    2001-12-01

    To date, atmospheric water isotope modeling has been performed on a global scale. The development of a stable water isotope scheme in a mesoscale model will lead to a simulated spatial distribution that will improve our understanding of present day climate variability, as well as historical climate patterns. The purpose of this study was to add water isotope tracers to the regional atmospheric model MM5 (NCAR's Mesoscale Model 5) in order to link existing global and basin-scale isotope models, and to work toward an improved knowledge of the water budget over the ARM site. In order to include isotopic processes in MM5, eight new prognostic variables were added to the model's dynamical core. These are the isotopic mixing ratios for water vapor, cloud liquid water, cloud ice, and rain for the stable isotopes O18 and deuterium. The isotopes are treated in a manner similar to the natural water vapor, cloud liquid water, etc. in terms of diffusion, advection, nudging, and filtering. Isotope fractionation and diffusion are handled using the approach of Gedzelman and Arnold (1994). Processes treated in this model are fractionation during deposition of water vapor onto cloud ice and condensation of water vapor onto cloud water, and also diffusive exchange of isotopes between vapor and falling rain drops. The bulk flux model of Hoffman et al. (1998) is used here as a first order approximation for isotopic evaporative processes. For the runs to be discussed here, lateral boundary conditions were generated by the Melbourne University General Circulation Model. This GCM runs at a resolution of R21, and predicts values of the O18 and deuterium mixing ratios at each grid point. Results of preliminary model runs will be discussed.

  15. Assessing groundwater recharge in an Andean closed basin using isotopic characterization and a rainfall-runoff model: Salar del Huasco basin, Chile

    Science.gov (United States)

    Uribe, Javier; Muñoz, José F.; Gironás, Jorge; Oyarzún, Ricardo; Aguirre, Evelyn; Aravena, Ramón

    2015-11-01

    Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial plains. Salt flats in the closed basins in arid northern Chile are extremely important ecological niches. The Salar del Huasco, one of these salt flats located in the high plateau (Altiplano), is a Ramsar site located in a national park and is composed of a wetland ecosystem rich in biodiversity. The proper management of the groundwater, which is essential for the wetland function, requires accurate estimates of recharge in the Salar del Huasco basin. This study quantifies the spatio-temporal distribution of the recharge, through combined use of isotopic characterization of the different components of the water cycle and a rainfall-runoff model. The use of both methodologies aids the understanding of hydrological behavior of the basin and enabled estimation of a long-term average recharge of 22 mm/yr (i.e., 15 % of the annual rainfall). Recharge has a high spatial variability, controlled by the geological and hydrometeorological characteristics of the basin, and a high interannual variability, with values ranging from 18 to 26 mm/yr. The isotopic approach allowed not only the definition of the conceptual model used in the hydrological model, but also eliminated the possibility of a hydrogeological connection between the aquifer of the Salar del Huasco basin and the aquifer that feeds the springs of the nearby town of Pica. This potential connection has been an issue of great interest to agriculture and tourism activities in the region.

  16. The BR eigenvalue algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Geist, G.A. [Oak Ridge National Lab., TN (United States). Computer Science and Mathematics Div.; Howell, G.W. [Florida Inst. of Tech., Melbourne, FL (United States). Dept. of Applied Mathematics; Watkins, D.S. [Washington State Univ., Pullman, WA (United States). Dept. of Pure and Applied Mathematics

    1997-11-01

    The BR algorithm, a new method for calculating the eigenvalues of an upper Hessenberg matrix, is introduced. It is a bulge-chasing algorithm like the QR algorithm, but, unlike the QR algorithm, it is well adapted to computing the eigenvalues of the narrowband, nearly tridiagonal matrices generated by the look-ahead Lanczos process. This paper describes the BR algorithm and gives numerical evidence that it works well in conjunction with the Lanczos process. On the biggest problems run so far, the BR algorithm beats the QR algorithm by a factor of 30--60 in computing time and a factor of over 100 in matrix storage space.

  17. Stalagmite carbon isotopes and dead carbon proportion (DCP) in a near-closed-system situation: An interplay between sulphuric and carbonic acid dissolution

    Science.gov (United States)

    Bajo, Petra; Borsato, Andrea; Drysdale, Russell; Hua, Quan; Frisia, Silvia; Zanchetta, Giovanni; Hellstrom, John; Woodhead, Jon

    2017-08-01

    In this study, the 'dead carbon proportion' (DCP) calculated from combined U-Th and radiocarbon analyses was used to explore the carbon isotope systematics in Corchia Cave (Italy) speleothems, using the example of stalagmite CC26 which grew during the last ∼12 ka. The DCP values in CC26 are among the highest ever recorded in a stalagmite, spanning the range 44.8-68.8%. A combination of almost closed-system conditions and sulphuric acid dissolution (SAD) are proposed as major drivers in producing such a high DCP with minor contribution from old organic matter from the deep vadose zone. The long-term decrease in both DCP and δ13C most likely reflects post-glacial soil recovery above the cave, with a progressive increase of soil CO2 contribution to the total dissolved inorganic carbon (DIC). Pronounced millennial-scale shifts in DCP and relatively small coeval but antipathetic changes in δ13C are modulated by the effects of hydrological variability on open and closed-system dissolution, SAD and prior calcite precipitation. Hence, the DCP in Corchia Cave speleothems represents an additional proxy for rainfall amount.

  18. Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: Applications to problems of hydrothermal alteration of igneous rocks and Precambrian iron formations

    Science.gov (United States)

    Gregory, R.T.; Criss, R.E.; Taylor, H.P.

    1989-01-01

    The systematics of stable-isotope exchange between minerals and fluids are examined in the context of modal mineralogical variations and mass-balance considerations, both in closed and in open systems. On mineral-pair ??18O plots, samples from terranes that have exchanged with large amounts of fluid typically map out steep positively-sloped non-equilibrium arrays. Analytical models are derived to explain these effects; these models allow for different exchange rates between the various minerals and the external fluids, as well as different fluid fluxes. The steep arrays are adequately modelled by calculated isochron lines that involve the whole family of possible exchange trajectories. These isochrons have initially-steep near-vertical positive slopes that rotate toward a 45?? equilibrium slope as the exchange process proceeds to completion. The actual data-point array is thus analogous to the hand of an "isotopic clock" that measures the duration of the hydrothermal episode. The dimensionless ratio of the volumetric fluid flux to the kinetic rate parameter ( u k) determines the shape of each individual exchange trajectory. In a fluid-buffered system ( u k ??? 1), the solutions to the equations: (1) are independent of the mole fractions of the solid phases; (2) correspond to Taylor's open-system water/rock equation; and (3) yield straight-line isochrons that have slopes that approach 1 f, where f is the fraction reacted of the more sluggishly exchanging mineral. The isochrons for this simple exchange model are closely congruent with the isochrons calculated for all of the more complex models, thereby simplifying the application of theory to actual hydrothermal systems in nature. In all of the models an order of magnitude of time (in units of kt) separates steep non-equilibrium arrays (e.g., slope ??? 10) from arrays approaching an equilibrium slope of unity on a ??-?? diagram. Because we know the approximate lifetimes of many hydrothermal systems from geologic and

  19. ISOTOPE SEPARATORS

    Science.gov (United States)

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  20. Estimation of ecosystem respiration and its components by means of stable isotopes and improved closed-chamber methods

    DEFF Research Database (Denmark)

    Brændholt, Andreas

    Ecosystem respiration (Reco) is the second largest flux of CO2 between the biosphere and the atmosphere. It consists of several components, such as plant respiration and soil respiration (Rsoil), each of which may respond differently to abiotic factors, and thus to global climate change. Rsoil...... was measured by the eddy covariance method and the components of tree stem respiration (Rstem), heterotrophic Rsoil from trenched soil, heterotrophic and autotrophic Rsoil from intact soil, and coarse root respiration (Rroot) were measured every two hours by automated closed-chambers for one year. We found....... In contrast, Rsoil showed the lowest respiration during daytime with no clear difference in the diel pattern between the intact and trenched soil plots. Finally, we calculated the annual Rsoil for different transects at the site, and found that annual Rsoil estimated from a previously used transect...

  1. Stable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates

    Science.gov (United States)

    Hudson, Adam M.; Quade, Jay; Ali, Guleed; Boyle, Douglas; Bassett, Scott; Huntington, Katharine W.; De los Santos, Marie G.; Cohen, Andrew S.; Lin, Ke; Wang, Xiangfeng

    2017-09-01

    Isotopic compositions of lacustrine carbonates are commonly used for dating and paleoenvironmental reconstructions. Here we use carbonate δ13C and δ18O, clumped (Δ47), and 14C compositions to better understand the carbonate isotope system in closed-basin lakes and trace the paleohydrologic and temperature evolution in the Chewaucan closed-basin lake system, northern Great Basin, USA, over the Last Glacial/Holocene transition. We focus on shorezone tufas to establish that they form in isotopic equilibrium with lake water and DIC, they can be dated reliably using 14C, and their clumped isotope composition can be used to reconstruct past lake temperature. Calculations of the DIC budget and reservoir age for the lake indicate residence time is short, and dominated by exchange with atmospheric CO2 at all past lake levels. Modern lake DIC and shorezone tufas yield δ13C and 14C values consistent with isotopic equilibrium with recent fossil fuel and bomb-influenced atmospheric CO2, supporting these calculations. δ13C values of fossil tufas are also consistent with isotopic equilibrium with pre-industrial atmospheric CO2 at all shoreline elevations. This indicates that the 14C reservoir effect for this material is negligible. Clumped isotope (Δ47) results indicate shorezone tufas record mean annual lake temperature. Modern (average 13 ± 2 °C) and 18 ka BP-age tufas (average 6 ± 2 °C) have significantly different temperatures consistent with mean annual temperature lowering of 7 ± 3 °C (1 SE) under full glacial conditions. For shorezone tufas and other lake carbonates, including spring mounds, mollusk shells, and ostracod tests, overall δ13C and δ18O values co-vary according to the relative contribution of spring and lacustrine end member DIC and water compositions in the drainage system, but specific isotope values depend strongly upon sample context and are not well correlated with past lake depth. This contrasts with the interpretation that carbonate

  2. Stable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates

    Science.gov (United States)

    Hudson, Adam; Quade, Jay; Ali, Guleed; Boyle, Douglas P.; Bassett, Scott; Huntington, Katharine W.; De los Santos, Marie G.; Cohen, Andrew S.; Lin, Ke; Wang, Xiangfeng

    2017-01-01

    Isotopic compositions of lacustrine carbonates are commonly used for dating and paleoenvironmental reconstructions. Here we use carbonate δ13C and δ18O, clumped (Δ47), and 14C compositions to better understand the carbonate isotope system in closed-basin lakes and trace the paleohydrologic and temperature evolution in the Chewaucan closed-basin lake system, northern Great Basin, USA, over the Last Glacial/Holocene transition. We focus on shorezone tufas to establish that they form in isotopic equilibrium with lake water and DIC, they can be dated reliably using 14C, and their clumped isotope composition can be used to reconstruct past lake temperature. Calculations of the DIC budget and reservoir age for the lake indicate residence time is short, and dominated by exchange with atmospheric CO2 at all past lake levels. Modern lake DIC and shorezone tufas yield δ13C and 14C values consistent with isotopic equilibrium with recent fossil fuel and bomb-influenced atmospheric CO2, supporting these calculations. δ13C values of fossil tufas are also consistent with isotopic equilibrium with pre-industrial atmospheric CO2 at all shoreline elevations. This indicates that the 14C reservoir effect for this material is negligible. Clumped isotope (Δ47) results indicate shorezone tufas record mean annual lake temperature. Modern (average 13 ± 2 °C) and 18 ka BP-age tufas (average 6 ± 2 °C) have significantly different temperatures consistent with mean annual temperature lowering of 7 ± 3 °C (1 SE) under full glacial conditions. For shorezone tufas and other lake carbonates, including spring mounds, mollusk shells, and ostracod tests, overall δ13C and δ18O values co-vary according to the relative contribution of spring and lacustrine end member DIC and water compositions in the drainage system, but specific isotope values depend strongly upon sample context and are not well correlated with past lake depth. This contrasts with the interpretation that carbonate

  3. Three closely related 1-(naphthalen-2-yl)prop-2-en-1-ones: pseudosymmetry, disorder and supramoleular assembly mediated by C-H...π and C-Br...π interactions.

    Science.gov (United States)

    Girisha, Marisiddaiah; Sagar, Belakavadi K; Yathirajan, Hemmige S; Rathore, Ravindranath S; Glidewell, Christopher

    2017-02-01

    It has been observed that when electron-rich naphthyl rings are present in chalcones they can participate in π-π stacking interactions, and this can play an important role in orientating inhibitors within the active sites of enzymes, while chalcones containing heterocyclic substituents additionally exhibit fungistatic and fungicidal properties. With these considerations in mind, three new chalcones containing 2-naphthyl substituents were prepared. 3-(4-Fluorophenyl)-1-(naphthalen-2-yl)prop-2-en-1-one, C19H13FO, (I), crystallizes with Z' = 2 in the space group P-1 and the four molecules in the unit cell adopt an arrangement which resembles that in the space group P21/a. Although 3-(4-bromophenyl)-1-(naphthalen-2-yl)prop-2-en-1-one, C19H13BrO, (II), with Z' = 1, is not isostructural with (I), the molecules of (I) and (II) adopt very similar conformations. In 1-(naphthalen-2-yl)-3-(thiophen-2-yl)prop-2-en-1-one, C17H12OS, (III), the thiophene unit is disordered over two sets of atomic sites, with occupancies of 0.780 (3) and 0.220 (3), which are related by a near 180° rotation of the thiophene unit about its exocyclic C-C bond. The molecules of compound (I) are linked by three independent C-H...π(arene) hydrogen bonds to form centrosymmetric octamolecular aggregates, whereas the molecules of compound (II) are linked into molecular ladders by a combination of C-H...π(arene) and C-Br...π(arene) interactions, and those of compound (III) are linked into centrosymmetric dimers by C-H...π(thiophene) interactions.

  4. Degradation of methyl bromide and methyl chloride in soil microcosms: Use of stable C isotope fractionation and stable isotope probing to identify reactions and the responsible microorganisms

    Science.gov (United States)

    Miller, L.G.; Warner, K.L.; Baesman, S.M.; Oremland, R.S.; McDonald, I.R.; Radajewski, S.; Murrell, J.C.

    2004-01-01

    Bacteria in soil microcosm experiments oxidized elevated levels of methyl chloride (MeCl) and methyl bromide (MeBr), the former compound more rapidly than the latter. MeBr was also removed by chemical reactions while MeCl was not. Chemical degradation dominated the early removal of MeBr and accounted for more than half of its total loss. Fractionation of stable carbon isotopes during chemical degradation of MeBr resulted in a kinetic isotope effect (KIE) of 59 ?? 7???. Soil bacterial oxidation dominated the later removal of MeBr and MeCl and was characterized by different KIEs for each compound. The KIE for MeBr oxidation was 69 ?? 9??? and the KIE for MeCl oxidation was 49 ?? 3???. Stable isotope probing revealed that different populations of soil bacteria assimilated added 13C-labeled MeBr and MeCl. The identity of the active MeBr and MeCl degrading bacteria in soil was determined by analysis of 16S rRNA gene sequences amplified from 13C-DNA fractions, which identified a number of sequences from organisms not previously thought to be involved in methyl halide degradation. These included Burkholderia , the major clone type in the 13C-MeBr fraction, and Rhodobacter, Lysobacter and Nocardioides the major clone types in the 13C-MeCl fraction. None of the 16S rRNA gene sequences for methyl halide oxidizing bacteria currently in culture (including Aminobacter strain IMB-1 isolated from fumigated soil) were identified. Functional gene clone types closely related to Aminobacter spp. were identified in libraries containing the sequences for the cmuA gene, which codes for the enzyme known to catalyze the initial step in the oxidation of MeBr and MeCl. The cmuA gene was limited to members of the alpha-Proteobacteria whereas the greater diversity demonstrated by the 16S rRNA gene may indicate that other enzymes catalyze methyl halide oxidation in different groups of bacteria. Copyright ?? 2004 Elsevier Ltd.

  5. Stable isotope trophic patterns in echinoderm megafauna in close proximity to and remote from Gulf of Mexico lower slope hydrocarbon seeps

    Science.gov (United States)

    Carney, Robert Spencer

    2010-11-01

    Hydrocarbon-seep communities in the Gulf of Mexico have a high biomass that is exploited as a food source to varying degrees by the photosynthesis-dependent fauna inhabiting the surrounding mud bottom. A decline concurrent with ocean depth in detritus influx to that background habitat results in a much lower background biomass. The biomass contrast between population-rich seeps and depauperate mud bottom leads to the prediction that seep utilization by the background fauna should be extensive at all depths and should increase with depth. Species depth zonation makes like-species comparisons over the full depth of the Gulf of Mexico impossible. Seeps and normal bottom above 1000 m have different fauna from those below 1000 m. Lower slope seeps are surrounded by a fauna rich in echinoderm species, especially asteroids, ophiuroids, and holothuroids. All three taxa have species that are abundant within seeps and are probably endemic to them. They also contain species found only in mud background or within mud and seeps backgrounds. Tissue analyses of δ13C and δ15N of echinoderms collected by ROV within seeps and trawling away from seeps indicate a pattern of utilization similar to that found in upper slope seeps exploited by different taxa. Seastar and ophiuroid species abundant in or endemic to seeps have tissue isotope values reflecting seep chemosynthetic input via a free-living microbial detritus or predation. A single seep-endemic deposit-feeding holothuroid showed distinct seep tissue values. Background deposit-feeding holothuroids collected within seeps showed either no or only minor incorporation of seep carbon, indicating either a lack of access to seep detritus or short feeding times within the seep. A predicted extensive utilization of seep productivity at the deeper seeps was not found. Seeps may be relatively closed systems that require special adaptations of species in order for them to enter, exploit, and survive. Alternately, the surrounding deep

  6. Statistical clumped isotope signatures

    Science.gov (United States)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  7. BrO measurements over the Eastern North-Atlantic

    Directory of Open Access Journals (Sweden)

    U. Platt

    2009-12-01

    Full Text Available The aim of the work presented here was to detect BrO in the marine boundary layer over the Eastern North-Atlantic by Multi AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS of scattered sunlight. With this technique, information about the concentration and the vertical profile of trace gases in the atmosphere can be gained. BrO can be formed in the marine atmosphere by degradation of biogenic organohalogens or by oxidation of bromide in sea salt aerosol. BrO influences the chemistry in marine air in many ways, e.g. since it catalytically destroys ozone, changes the NO2/NO-ratio as well as the OH/HO2-ratio and oxidises DMS. However, the abundance and the significance of BrO in the marine atmosphere is not yet fully understood. <br>> We report on data collected during a ship cruise, which took place along the West African Coast in February 2007, within the framework of the Surface Ocean PRocesses in the ANthropocene project (SOPRAN. Tropospheric BrO could be detected during this cruise at peak mixing ratios of (10.2±3.7 ppt at an assumed layer height of 1 km on 18 February 2007. Furthermore, it was found that the mean BrO concentrations increased when cruising close to the African Coast suggesting that at least part of the BrO might have originated from there.

  8. Pathways for the OH + Br2 → HOBr + Br and HOBr + Br → HBr + BrO Reactions.

    Science.gov (United States)

    Wang, Hongyan; Qiu, Yudong; Schaefer, Henry F

    2016-02-11

    The OH radical reaction with Br2 and the subsequent reaction HOBr + Br are of exceptional importance to atmospheric chemistry and environmental chemistry. The entrance complex, transition state, and exit complex for both reactions have been determined using the coupled-cluster method with single, double, and perturbative triple excitations CCSD(T) with correlation consistent basis sets up to size cc-pV5Z and cc-pV5Z-PP. Coupled cluster effects with full triples (CCSDT) and full quadruples (CCSDTQ) are explicitly investigated. Scalar relativistic effects, spin-orbit coupling, and zero-point vibrational energy corrections are evaluated. The results from the all-electron basis sets are compared with those from the effective core potential (ECP) pseudopotential (PP) basis sets. The results are consistent. The OH + Br2 reaction is predicted to be exothermic 4.1 ± 0.5 kcal/mol, compared to experiment, 3.9 ± 0.2 kcal/mol. The entrance complex HO···BrBr is bound by 2.2 ± 0.2 kcal/mol. The transition state lies similarly well below the reactants OH + Br2. The exit complex HOBr···Br is bound by 2.7 ± 0.6 kcal/mol relative to separated HOBr + Br. The endothermicity of the reaction HOBr + Br → HBr + BrO is 9.6 ± 0.7 kcal/mol, compared with experiment 8.7 ± 0.3 kcal/mol. For the more important reverse (exothermic) HBr + BrO reaction, the entrance complex BrO···HBr is bound by 1.8 ± 0.6 kcal/mol. The barrier for the HBr + BrO reaction is 6.8 ± 0.9 kcal/mol. The exit complex (Br···HOBr) for the HBr + BrO reaction is bound by 1.9 ± 0.2 kcal/mol with respect to the products HOBr + Br.

  9. Chlorine and Bromine Isotope Fractionation of Halogenated Organic Pollutants on Gas Chromatography Columns

    OpenAIRE

    Tang, Caiming; Tan, Jianhua; Xiong, Songsong; Liu, Jun; Fan, Yujuan; Peng, Xianzhi

    2017-01-01

    Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a useful approach for degradation pathway investigation and source appointment of halogenated organic pollutants (HOPs). CSIA-Cl/Br is usually conducted by gas chromatography-mass spectrometry (GC-MS), which could be negatively impacted by chlorine and bromine isotope fractionation of HOPs on GC columns. In this study, 31 organochlorines and 4 organobromines were systematically investigated in terms of Cl/Br isotope f...

  10. Brønsted acid-promoted C-H bond cleavage via electron transfer from toluene derivatives to a protonated nonheme iron(IV)-oxo complex with no kinetic isotope effect.

    Science.gov (United States)

    Park, Jiyun; Lee, Yong-Min; Nam, Wonwoo; Fukuzumi, Shunichi

    2013-04-03

    The reactivity of a nonheme iron(IV)-oxo complex, [(N4Py)Fe(IV)(O)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), was markedly enhanced by perchloric acid (70% HClO4) in the oxidation of toluene derivatives. Toluene, which has a high one-electron oxidation potential (Eox = 2.20 V vs SCE), was oxidized by [(N4Py)Fe(IV)(O)](2+) in the presence of HClO4 in acetonitrile (MeCN) to yield a stoichiometric amount of benzyl alcohol, in which [(N4Py)Fe(IV)(O)](2+) was reduced to [(N4Py)Fe(III)(OH2)](3+). The second-order rate constant (kobs) of the oxidation of toluene derivatives by [(N4Py)Fe(IV)(O)](2+) increased with increasing concentration of HClO4, showing the first-order dependence on [HClO4]. A significant kinetic isotope effect (KIE) was observed when mesitylene was replaced by mesitylene-d12 in the oxidation with [(N4Py)Fe(IV)(O)](2+) in the absence of HClO4 in MeCN at 298 K. The KIE value drastically decreased from KIE = 31 in the absence of HClO4 to KIE = 1.0 with increasing concentration of HClO4, accompanied by the large acceleration of the oxidation rate. The absence of KIE suggests that electron transfer from a toluene derivative to the protonated iron(IV)-oxo complex ([(N4Py)Fe(IV)(OH)](3+)) is the rate-determining step in the acid-promoted oxidation reaction. The detailed kinetic analysis in light of the Marcus theory of electron transfer has revealed that the acid-promoted C-H bond cleavage proceeds via the rate-determining electron transfer from toluene derivatives to [(N4Py)Fe(IV)(OH)](3+) through formation of strong precursor complexes between toluene derivatives and [(N4Py)Fe(IV)(OH)](3+).

  11. On-line orientation of bromine isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Barham, C.G.; Alghamdi, S.S.; Grant, I.S. (Schuster Lab., Manchester Univ. (United Kingdom)); Bhagwat, A.; Singleton, B.D.D.; Walker, P.M. (Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom)); Booth, M.; Lindroos, M.; Rikovska, J.; Stone, N.J. (Clarendon Lab., Oxford Univ. (United Kingdom))

    1992-11-01

    Assignments for the principal Nilsson configuration in light [beta][sup +]-decaying bromine isotopes were proposed in a contribution to the OLNO-1 conference. These assignments were made on the basis of magnetic moments derived from the temperature dependence of anisotropies in daughter Se isotopes observed in the DOLIS-COLD facility at Daresbury. Anisotropy measurements have since been extended to a lower base temperature in [sup 74m]Br and [sup 72g]Br decay, leading to more stringent limits on the ground state moment of [sup 72]Br. The proposed [pi][312]3/2 configuration for [sup 75]Br has also now been confirmed by a measurement of the sign of its magnetic moment. This was done by observing the [beta]-asymmetry in [sup 75]Br decay using high purity Si detectors mounted within the dilution refrigerator. (orig.).

  12. Assessment of surface reactivity of thorium oxide in conditions close to chemical equilibrium by isotope exchange {sup 229}Th/{sup 232}Th method

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki-Muresan, Tomo; Perrigaud, Katy; Vandenborre, Johan; Ribet, Solange; Grambow, Bernd [Nantes Univ., CNRS/IN2P3 (France). SUBATECH Unite Mixte de Recherche 6457; Takamasa, Inai [TOKAI Univ., Kanagawa (Japan)

    2017-08-01

    This work aims to assess the solubility and the surface reactivity of crystallized thorium at pH 3.0 in presence of three types of solids: synthesized powder at 1300 C, crushed kernel, and intact kernel. In this study, the kernel is composed by the core solid from high temperature reactors (HTR) sphere particles. The originality of this work consisted in following in a sequential order the kinetic of dissolution, the surface reactivity in presence of isotope tracer {sup 229}Th, and its desorption process. Long time experiments (634 days) allowed to get deeper understanding on the behavior of the surface reactivity in contact with the solution. Solubility values are ranging from 0.3 x 10{sup -7} mol.L{sup -1} to 3 x 10{sup -7} mol.L{sup -1} with a dissolution rate of 10{sup -6}-10{sup -4} g.m{sup -2} day{sup -1}. PHREEQC modeling showed that crystallized ThO{sub 2}(cr, 20 nm) phase controls the equilibrium in solution. Isotope exchange between {sup 229}Th and {sup 232}Th indicated that well-crystallized phase exist as an inert surface regarding to the absence of exchange between surface solid and solution.

  13. Production cross sections from 82Se fragmentation as indications of shell effects in neutron-rich isotopes close to the drip-line

    Science.gov (United States)

    Tarasov, O. B.; Portillo, M.; Morrissey, D. J.; Amthor, A. M.; Bandura, L.; Baumann, T.; Bazin, D.; Berryman, J. S.; Brown, B. A.; Chubarian, G.; Fukuda, N.; Gade, A.; Ginter, T. N.; Hausmann, M.; Inabe, N.; Kubo, T.; Pereira, J.; Sherrill, B. M.; Stolz, A.; Sumithrarachichi, C.; Thoennessen, M.; Weisshaar, D.

    2013-05-01

    Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 126 neutron-rich isotopes of elements 11≤Z≤32 were scanned using an experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 22≤Z≤25 (64Ti, 67V, 69Cr, and 72Mn). One event was registered consistent with 70Cr and another one with 75Fe. The production cross sections are correlated with Qg systematics to reveal trends in the data. The results presented here confirm our previous results from a similar measurement using a 76Ge beam and can be explained with a shell model that predicts a subshell closure at N=34 around Z=20. This is demonstrated by systematic trends and calculations with the abrasion-ablation model that are sensitive to separation energies.

  14. Production cross sections from 82Se fragmentation as indications of shell effects in neutron-rich isotopes close to the drip-line

    CERN Document Server

    Tarasov, O B; Morrissey, D J; Amthor, A M; Bandura, L; Baumann, T; Bazin, D; Berryman, J S; Brown, B A; Chubarian, G; Fukuda, N; Gade, A; Ginter, T N; Hausmann, M; Inabe, N; Kubo, T; Pereira, J; Sherrill, B M; Stolz, A; Sumithrarachichi, C; Thoennessen, M; Weisshaar, D

    2013-01-01

    Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 126 neutron-rich isotopes of elements 11 <= Z <= 32 were scanned using an experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 22 <= Z <= 25 (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. The production cross sections are correlated with Qg systematics to reveal trends in the data. The results presented here confirm our previous result from a similar measurement using a 76Ge beam, and can be explained with a shell model that predicts a subshell closure at N = 34 around Z = 20. This is demonstrated by systematic trends and calculations with the Abrasion-Ablation model that ...

  15. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling. Copyright © 2015, American Association for the Advancement of Science.

  16. Search for isotopic signatures of a supernova explosion close to the solar system in marine sediments; Recherche de signatures isotopiques dans les sediments marins de l'explosion d'une supernova proche du systeme solaire

    Energy Technology Data Exchange (ETDEWEB)

    Fitoussi, Caroline [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, (CSNSM) IN2P3/CNRS, Campus d' Orsay, Bat 108, 91405 Orsay (France)

    2006-06-15

    The recent observation of a {sup 60}Fe peak in a deep-sea ferro-manganese crust has been interpreted as due to a supernova explosion relatively close to the solar system 2.8 {+-} 0.4 Myr ago. To confirm this interpretation with better time-resolved measurements, and the simultaneous access, on the same sample, to other isotopes and geochemical phases, marine sediments seem to be a tool of choice. The objective of this work was to search for isotopic anomalies which would be characteristic for residues of this supernova. More specifically, {sup 129}I, {sup 60}Fe, and {sup 26}Al have been investigated, being measured by Accelerator Mass Spectrometry (AMS). Quantifying these nuclides' fluxes would help constrain stellar nucleosynthesis models. These residues are isotopes initially produced during hydrostatic and/or explosive nucleosynthesis. The physical conditions during the explosion (temperature, neutron density) are such that supernovae are thought to be good candidates for the astrophysical site of the r-process. The {sup 129}I study showed that measurement of pre-anthropogenic {sup 129}I/{sup 127}I ratios need a very strict control of the various potential {sup 129}I sources, especially when working with small quantities (micrograms) of iodine. This study revealed that the expected pre-anthropogenic {sup 129}I/{sup 127}I ratio for pre-nuclear samples in the marine environment shows a large discrepancy between theoretical calculations and experimental measurements. {sup 60}Fe and {sup 26}Al measurements allow us to conclude that, in the authigenic phase of the marine sediments, there is no {sup 60}Fe anomaly in the time interval defined by the signal found on the Fe-Mn crust (from 2.4 to 3.2 Myr), and no {sup 26}Al anomaly from 2.6 to 3.2 Myr. (author)

  17. Theoretical Evaluation of Intermolecular and Intramolecular Isotope Fractionations in Fragmentation

    OpenAIRE

    Tang, Caiming; Peng, Xianzhi

    2017-01-01

    Revelation of the effects of isotope fractionation during fragmentation in electron ionization mass spectrometry (EI-MS) on compound-specific isotope analysis of chlorine and bromine (CSIA-Cl/Br) may be of crucial significance, yet a theoretical basis for elucidating the effects is absent. This study provides a solid theoretical deduction regarding the isotope fractionation taking place during fragmentation in EI-MS. Both intermolecular and intramolecular isotope fractionations present in deh...

  18. Chlorine and bromine isotope fractionation of halogenated organic pollutants on gas chromatography columns.

    Science.gov (United States)

    Tang, Caiming; Tan, Jianhua; Xiong, Songsong; Liu, Jun; Fan, Yujuan; Peng, Xianzhi

    2017-09-08

    Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a powerful approach to investigate degradation pathways and apportion sources of halogenated organic pollutants (HOPs) in the environment. CSIA-Cl/Br is usually conducted by gas chromatography-mass spectrometry (GC-MS), which could be negatively impacted by isotope fractionation on GC columns. In this study, on-column Cl/Br isotope fractionation of 31 organochlorines and 4 organobromines was explored using GC-double focus magnetic-sector high resolution MS (GC-DFS-HRMS). Twenty-nine HOPs exhibited inverse Cl/Br isotope fractionation for which the heavier isotopologues eluted faster than the lighter ones on GC columns, and two polychlorinated biphenyls (PCB-138 and PCB-153) showed normal isotope fractionation, whereas the rest four HOPs did not show observable isotope fractionation. The isotope fractionation extents varied from -13.0‰ to 73.1‰. Mechanisms of the on-column Cl/Br isotope fractionation were tentatively elucidated with a modified two-film model. The results demonstrate that integrating peak area as complete as possible for separable chromatographic peaks and integrating the middle retention-time segments for the inseparable peaks are helpful to improve precision and accuracy of the CSIA-Cl/Br data. The findings of this study will shed light on development of CSIA-Cl/Br methods with respect to improving precision and accuracy. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. CsPb2Br5 Single Crystals: Synthesis and Characterization

    KAUST Repository

    Dursun, Ibrahim

    2017-08-02

    CsPb2Br5 is a ternary halogen-plumbate material with close characteristics to well-reported halide perovskites. Due to its unconventional two-dimensional structure, CsPb2Br5 is being looked at broadly for potential applications in optoelectronics. CsPb2Br5 investigations are currently limited to nanostructures and powder forms of the material, which present unclear and conflicting optical properties. In this study, we present the synthesis and characterization of CsPb2Br5 bulk single crystals, which enabled us to finally clarify the material\\'s optical features. Our CsPb2Br5 crystal has a two-dimensional structure with Pb2Br5- layers spaced by Cs+ cations, and exhibits a ~3.1 eV indirect bandgap with no emission in the visible spectrum.

  20. Stig Brøgger's Artists' Books

    DEFF Research Database (Denmark)

    Ørum, Tania; Hvis Kromann, Thomas

    Introduction and presentation of the many artist's books made by the Danish artist Stig Brøgger......Introduction and presentation of the many artist's books made by the Danish artist Stig Brøgger...

  1. Brændeovn med autopilot

    DEFF Research Database (Denmark)

    Illerup, Jytte Boll

    2013-01-01

    Ved at sætte brændeovnen på autopilot opnår man en bedre energiudnyttelse og en markant reduktion af luftforurenende stoffer. Automatisk styring af brændeovnen giver lige så lave emissioner hos forbrugeren som på testinstitutter, viser et forskningsprojekt mellem den jyske brændeovnproducent HWAM...

  2. New cross section measurements for production of the positron emitters {sup 75}Br and {sup 76}Br via intermediate energy proton induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Spahn, I.; Coenen, H.H.; Qaim, S.M. [Forschungszentrum Juelich GmbH, Juelich (DE). Inst. fuer Neurowissenschaften und Biophysik - Nuklearchemie (INB 4); Steyn, G.F.; Vermeulen, C. [Radionuclide Production Group, iThemba LABS, Somerset West (South Africa); Kovacs, Z.; Szelecsenyi, F. [Cyclotron Dept., Inst. of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary)

    2009-07-01

    The radionuclides {sup 75}Br and {sup 76}Br are of considerable interest for application in Position Emission Tomography (PET). For their production so far mostly low-energy or low-yield production processes have been employed. In this work the production of both isotopes was investigated using intermediate energy proton induced reactions and enriched target materials. Cross section data of the {sup 77,78,80}Se(p, xn){sup 75}Br processes were measured up to 66 MeV and those of the {sup 77,78,80}Se(p, xn){sup 76}Br processes up to 85 MeV. The measured excitation functions were compared with calculated results of the nuclear model code ALICE-IPPE. From the experimental excitation curves, thick target yields were calculated. They are fairly high over the investigated intermediate energy ranges. The production possibilities of {sup 75}Br and {sup 76}Br via various routes and the radionuclidic impurities associated with them are discussed. (orig.)

  3. Balloon-borne stratospheric BrO measurements: comparison with Envisat/SCIAMACHY BrO limb profiles

    Directory of Open Access Journals (Sweden)

    M. Dorf

    2006-01-01

    Full Text Available For the first time, results of four stratospheric BrO profiling instruments, are presented and compared with reference to the SLIMCAT 3-dimensional chemical transport model (3-D CTM. Model calculations are used to infer a BrO profile validation set, measured by 3 different balloon sensors, for the new Envisat/SCIAMACHY (ENVIronment SATellite/SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY satellite instrument. The balloon observations include (a balloon-borne in situ resonance fluorescence detection of BrO (Triple, (b balloon-borne solar occultation DOAS measurements (Differential Optical Absorption Spectroscopy of BrO in the UV, and (c BrO profiling from the solar occultation SAOZ (Systeme d'Analyse par Observation Zenithale balloon instrument. Since stratospheric BrO is subject to considerable diurnal variation and none of the measurements are performed close enough in time and space for a direct comparison, all balloon observations are considered with reference to outputs from the 3-D CTM. The referencing is performed by forward and backward air mass trajectory calculations to match the balloon with the satellite observations. The diurnal variation of BrO is considered by 1-D photochemical model calculation along the trajectories. The 1-D photochemical model is initialised with output data of the 3-D model with additional constraints on the vertical transport, the total amount and photochemistry of stratospheric bromine as given by the various balloon observations. Total [Bry]=(20.1±2.5 pptv obtained from DOAS BrO observations at mid-latitudes in 2003, serves as an upper limit of the comparison. Most of the balloon observations agree with the photochemical model predictions within their given error estimates. First retrieval exercises of BrO limb profiling from the SCIAMACHY satellite instrument on average agree to around 20% with the photochemically-corrected balloon observations of the remote sensing instruments (SAOZ

  4. Isotope separation

    Science.gov (United States)

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  5. Ozone Depletion Potential of CH3Br

    Science.gov (United States)

    Sander, Stanley P.; Ko, Malcolm K. W.; Sze, Nien Dak; Scott, Courtney; Rodriquez, Jose M.; Weisenstein, Debra K.

    1998-01-01

    The ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model-calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + H02, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrON02, and the heterogeneous conversion of BrON02 to HOBR and HN03 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model-calculated concentration of HBr (approximately 0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about I pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + H02. Although the DeAlore et al. evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + H02.

  6. Aagesta-BR3 Decommissioning Cost. Comparison and Benchmarking Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Varley, Geoff [NAC International, Henley on Thames (United Kingdom)

    2002-11-01

    25 is equipment. The BR3 work packages described in this report add up to something like 83,000 labour hours plus about MSEK 13 of investments and consumables costs. At Swedish average team labour rates 83,000 hours would equate to about MSEK 52. Adding the investment cost of MSEK 13 gives a total of about MSEK 65. This of course is quite close to the Aagesta figure but it would be wrong to draw immediate, firm conclusions based on these data. Such a comparison should take into account, inter alia: The number and relative sizes of the equipment decontaminated and dismantled at Aagesta and BR3. The assumed productivity in the Aagesta estimate compared to the actual BR3 figures. The physical scale of the Aagesta reactor is somewhat larger than the BR3 reactor, so all other things being equal, one might expect the Aagesta decommissioning cost estimate to be higher than for BR3. Aagesta has better access overall, which should help to constrain costs. The productivity ratio for workers at BR3 on average was high - generally 80 per cent or more, so this is unlikely to be exceeded at Aagesta and might not be equalled, which would tend to push the Aagesta cost up relative to the BR3 situation. There is an additional question of the possible extra work performed at BR3 due to the R and D nature of the project. The BR3 data analysed has tried to strip away any such 'extra' work but nevertheless there may be some residual effect on the final numbers. Analysis and comparison of individual work packages has raised several conclusions, as follows: The constructed cost for Aagesta using BR3 benchmark data is encouragingly close to the Aagesta estimate value but it is not clear that the way of deriving the Aagesta estimate for decontamination was entirely rigorous. The reliability of the Aagesta estimate on these grounds therefore might reasonably be questioned. A significant discrepancy between the BR3 and Aagesta cases appears to exist in respect of the volumes of waste

  7. Microhardness studies on as-grown faces of NaClO3 and NaBrO3 ...

    Indian Academy of Sciences (India)

    The hardness studies point out that NaBrO3 is harder than NaClO3 ( ≈ 100 kg/mm2), this could be due to strong inter ionic forces acting between Na–Br in NaBrO3 crystals. Using Gilman's empirical relation, hardness values are calculated from the values of elastic constants (44) and are found to be close to the ...

  8. Atmospheric fate of CF sub 3 Br, CF sub 2 Br sub 2 , CF sub 2 ClBr, and CF sub 2 BrCF sub 2 Br

    Energy Technology Data Exchange (ETDEWEB)

    Burkholder, J.B.; Wilson, R.R.; Gierczak, T.; Talukdar, R.; McKeen, S.A.; Orlando, J.J.; Vaghjiani, G.L.; Ravishankara, A.R. (National Oceanic and Atmospheric Administration, Boulder, CO (USA) Univ. of Colorado, Boulder (USA))

    1991-03-20

    The temperature dependent UV absorption cross sections of the haloalkanes CF{sub 3}Br, CF{sub 2}ClBr, CF{sub 2}Br{sub 2}, and CF{sub 2}BrCF{sub 2} are reported. The UV absorption cross sections were measured over the temperature range 210 to 296 K and the wavelength range 190 to 320 nm. Upper limits of the rate coefficients for the reactions of OH with CF{sub 3}Br, CF{sub 2}Br{sub 2}, CF{sub 2}ClBr, and CF{sub 2}BrCF{sub 2}Br were also determined using both pulsed photolysis and flow tube techniques. The rate coefficients at 296 K were found to be <1.2 {times} 10{sup {minus}16}, <1.5 {times} 10{sup {minus}16}, <5.0 {times} 10{sup {minus}16}, and <1.5 {times} 10{sup {minus}16} cm{sup 3} molec{sup {minus}1} s{sup {minus}1} for CF{sub 3}Br, CF{sub 2}ClBr, CF{sub 2}BrCF{sub 2}Br, respectively. The UV absorption cross-section data and OH reaction rate coefficients of these species were combined with a one-dimensional model to yield atmospheric lifetimes of 65, 16, 3.2, and <20 years for CF{sub 3}Br, CF{sub 2}ClBr, CF{sub 2}Br{sub 2}, and CF{sub 2}BrCF{sub 2}Br, respectively.

  9. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  10. Isotope Identification

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-18

    The objective of this training modules is to examine the process of using gamma spectroscopy for radionuclide identification; apply pattern recognition to gamma spectra; identify methods of verifying energy calibration; and discuss potential causes of isotope misidentification.

  11. Cd4As2Br3

    Directory of Open Access Journals (Sweden)

    Mohammed Kars

    2014-03-01

    Full Text Available Single crystals of Cd4As2Br3 (tetracadmium biarsenide tribromide were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I and contains two independent As atoms on special positions with site symmetry -3 and two independent Cd atoms, of which one is on a special position with site symmetry -3. The Cd4As2Br3 structure consists of AsCd4 tetrahedra sharing vertices with isolated As2Cd6 octahedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd...Br contacts.

  12. buFacile synthesis and characterization of CsPbBr3 and CsPb2Br5 ...

    Indian Academy of Sciences (India)

    65

    CsPb2Br5 powders show a white color. Based on the results of the XRD analysis, it can be seen that the Cs+/Pb2+ mole ratio has the effect on the phase of final product in this synthesis process. Generally speaking, there is a reaction occurring for the formation of CsPbBr3 by CsBr and. PbBr2: CsBr + PbBr2 → CsPbBr3. (1).

  13. Simultaneous spectroscopy of $\\gamma$- rays and conversion electrons: Systematic study of EO transitions and intruder states in close vicinity of mid-shell point in odd-Au isotopes

    CERN Multimedia

    Venhart, M; Grant, A F; Petrik, K

    This proposal focuses on detailed systematic studies of the $\\beta$ /EC-decays of $^{179,181,183,185}$Hg leading to excited states in the neutron-deficient Au isotopes in the vicinity of the N=104 midshell. $\\gamma$-ray, X-ray and conversion electron de-excitations of odd-A Au isotopes will be studied simultaneously. These studies will address important structural questions such as the excitation energies of coexisting states, properties of multiple intruder states (i.e. intruder particles coupled to intruder cores) and mixing of coexisting structures. The unique combination of Hg beam purity and yields make ISOLDE a unique facility for these experiments.

  14. Structure and heats of formation of iodine fluorides and the respective closed-shell ions from CCSD(T) electronic structure calculations and reliable prediction of the steric activity of the free-valence electron pair in ClF6-, BrF6-, and IF6-.

    Science.gov (United States)

    Dixon, David A; Grant, Daniel J; Christe, Karl O; Peterson, Kirk A

    2008-06-16

    Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for IF, IF2-, IF2+, IF3, IF4-, IF4+, IF5, IF6-, IF6+, IF7, IF8-, BrF6-, and ClF6- from coupled cluster theory [CCSD(T)] calculations with effective-core potential correlation-consistent basis sets for I. In order to achieve near chemical accuracy (+/-1 kcal/mol), three corrections were added to the complete basis set binding energies based on frozen-core coupled-cluster theory energies: a correction for core-valence effects, a correction for scalar relativistic effects, and a correction for first-order atomic spin-orbit effects. Vibrational zero-point energies were computed at the coupled-cluster level of theory except for IF6-, IF7, and IF8-. The calculated heats of formation for the neutral and ionic IFn fluorides were used to predict fluoride affinities. It is shown that high-level calculations are required to predict correctly the steric activity of the free-valence electron pair on the central atoms in IF6- (C3v), BrF6- (Oh), and ClF6- (Oh ). The vibrational spectrum of IF8- was reanalyzed, and complete mode descriptions for square-antiprismatic XF8 species of D4d symmetry are given.

  15. Stable isotope

    African Journals Online (AJOL)

    Results of the study suggest that there are two main carbon pathways for plankton and nekton in the Kariega estuary, carbon derived from the eelgrass and its associated epiphytes and carbon which has its origins in the salt marsh riparian vegetation and zooplankton. Keywords: stable isotope analysis; temperate estuary; ...

  16. Bromine and carbon isotope effects during photolysis of brominated phenols.

    Science.gov (United States)

    Zakon, Yevgeni; Halicz, Ludwik; Gelman, Faina

    2013-12-17

    In the present study, carbon and bromine isotope effects during UV-photodegradation of bromophenols in aqueous and ethanolic solutions were determined. An anomalous relatively high inverse bromine isotope fractionation (εreactive position up to +5.1‰) along with normal carbon isotope effect (εreactive position of -12.6‰ to -23.4‰) observed in our study may be attributed to coexistence of both mass-dependent and mass-independent isotope fractionation of C-Br bond cleavage. Isotope effects of a similar scale were observed for all the studied reactions in ethanol, and for 4-bromophenol in aqueous solution. This may point out related radical mechanism for these processes. The lack of any carbon and bromine isotope effects during photodegradation of 2-bromophenol in aqueous solution possibly indicates that C-Br bond cleavage is not a rate-limiting step in the reaction. The bromine isotope fractionation, without any detectable carbon isotope effect, that was observed for 3-bromophenol photolysis in aqueous solution probably originates from mass-independent fractionation.

  17. Max Brödel: his art, legacy, and contributions to neurosurgery through medical illustration.

    Science.gov (United States)

    Patel, Smruti K; Couldwell, William T; Liu, James K

    2011-07-01

    Max Brödel is considered the father of modern medical illustration. This report reviews his contributions to neurosurgery as a medical illustrator. Max Brödel, a young artist from Leipzig, Germany, was hired at Johns Hopkins Hospital in 1894, where he illustrated an operative textbook of gynecology for Howard A. Kelly. Although Brödel did not have any formal medical training, he quickly acquired knowledge of anatomy, pathology, physiology, and surgery. Brödel's extraordinary illustrations were characterized by an aerial perspective that conveyed the surgeon's operative viewpoint and precise surgical anatomy. He masterfully incorporated tissue realism with cross-sectional anatomy to accentuate concepts while maintaining topographical accuracy. Brödel's reputation spread quickly and resulted in collaborations with prominent surgeons, such as Cushing, Halsted, and Dandy. Cushing, who also possessed artistic talent, became a pupil of Brödel and remained a very close friend. In 1911, Brödel was appointed the director of the Department of Art as Applied to Medicine at Johns Hopkins, the first academic department of its kind in the world. For the next several decades, he trained generations of renowned medical illustrators. Just as Osler, Halsted, and Cushing passed their skills and knowledge to future leaders of medicine and surgery, Brödel did the same for the field of medical illustration. The advancement of neurosurgical education has been greatly facilitated by Max Brödel's artistic contributions. His unique ability to synthesize art and medicine resulted in timeless illustrations that remain indispensable to surgeons. The art produced by his legacy of illustrators continues to flourish in neurosurgical literature today.

  18. A new method of preparation of AgBr/TiO{sub 2} composites and investigation of their photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Xing Yangyang; Li Rui; Li Qiuye, E-mail: lqybys@yahoo.com.cn; Yang Jianjun [Henan University, Key Laboratory for Special Functional Materials (China)

    2012-12-15

    Silver bromide/titanium dioxide composites were first prepared using titanic acid nanobelts (TAN) as the TiO{sub 2} source. First, TAN reacted with AgNO{sub 3} to prepare Ag-incorporated TAN by the ion-exchange method, and then AgBr/TAN was obtained after adding NaBr. Finally, AgBr/TAN was transformed to AgBr/TiO{sub 2} composites by calcination. The post-treated calcination would not only convert TAN to TiO{sub 2} (H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} {yields} 2H{sub 2}O + 2TiO{sub 2}), but also increase the effective contact between AgBr and TiO{sub 2}, further to improve the separation of photo-generated electron-holes. The advantage of this preparation method is the small particle size (ca. 10-20 nm) and well dispersion of AgBr on the surface of TiO{sub 2}, and close contact between AgBr and TiO{sub 2}. The effect of the different calcination temperature on the morphology, structure, and properties of AgBr/TiO{sub 2} composites was investigated in detail. The AgBr/TiO{sub 2} composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). Comparing with pure TAN, AgBr, and AgBr/P25 mixture, the AgBr/TiO{sub 2} composites exhibited enhanced photocatalytic activity in decomposition of methyl orange (MO) under visible light irradiation.

  19. Cooperative effects of noncovalent bonds to the Br atom of halogen-bonded H3N...BrZ and HCN...BrZ (Z = F, Br) complexes.

    Science.gov (United States)

    McDowell, Sean A C; Joseph, Jerelle A

    2012-08-21

    A series of complexes formed between halogen-bonded H(3)N/HCN...BrZ (Z = Br, F) dimers and H(3)N/HCN...BrZ...XY (XY = HF, ClF, BeH(2), LiF) trimers were investigated at the MP2 and B3LYP levels of theory using a 6-31++G(d,p) basis set. Optimized structures, interaction energies, and other properties of interest were obtained. The addition of XY to the H(3)N/HCN...BrZ dyad leads to enhanced intermolecular binding with respect to the isolated monomers. This enhanced binding receives contributions from the electrostatic and inductive forces between the constituent pairs, with, in some instances, substantial three-body non-additive contributions to the binding energy. It was found that the XY = LiF interaction causes the greatest distortion of the H(3)N/HCN...BrZ halogen bond from the preferred linear orientation and also provides the strongest binding energy via the nonadditive energy.

  20. Chlorine and Bromine Isotope Fractionation of Halogenated Organic Compounds in Electron Ionization Mass Spectrometry

    OpenAIRE

    Tang, Caiming; Tan, Jianhua; Shi, Zhiqiang; Tang, Caixing; Xiong, Songsong; Liu, Jun; Fan, Yujuan; Peng, Xianzhi

    2017-01-01

    Revelation of chlorine and bromine isotope fractionation of halogenated organic compounds (HOCs) in electron ionization mass spectrometry (EI-MS) is crucial for compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) using gas chromatography EI-MS (GC-EI-MS). This study systematically investigated chlorine/bromine isotope fractionation in EI-MS of HOCs including 12 organochlorines and 5 organobromines using GC-double focus magnetic-sector high resolution MS (GC-DFS-HRMS). Chlorine/br...

  1. Nuclear import of transcription factor BR-C is mediated by its interaction with RACK1.

    Directory of Open Access Journals (Sweden)

    Daojun Cheng

    Full Text Available The transcription factor Broad Complex (BR-C is an early ecdysone response gene in insects and contains two types of domains: two zinc finger domains for the activation of gene transcription and a Bric-a-brac/Tramtrack/Broad complex (BTB domain for protein-protein interaction. Although the mechanism of zinc finger-mediated gene transcription is well studied, the partners interacting with the BTB domain of BR-C has not been elucidated until now. Here, we performed a yeast two-hybrid screen using the BTB domain of silkworm BR-C as bait and identified the receptor for activated C-kinase 1 (RACK1, a scaffolding/anchoring protein, as the novel partner capable of interacting with BR-C. The interaction between BR-C and RACK1 was further confirmed by far-western blotting and pull-down assays. Importantly, the disruption of this interaction, via RNAi against the endogenous RACK1 gene or deletion of the BTB domain, abolished the nuclear import of BR-C in BmN4 cells. In addition, RNAi against the endogenous PKC gene as well as phosphorylation-deficient mutation of the predicted PKC phosphorylation sites at either Ser373 or Thr406 in BR-C phenocopied RACK1 RNAi and altered the nuclear localization of BR-C. However, when BTB domain was deleted, phosphorylation mimics of either Ser373 or Thr406 had no effect on the nuclear import of BR-C. Moreover, mutating the PKC phosphorylation sites at Ser373 and Thr406 or deleting the BTB domain significantly decreased the transcriptional activation of a BR-C target gene. Given that RACK1 is necessary for recruiting PKC to close and phosphorylate target proteins, we suggest that the PKC-mediated phosphorylation and nuclear import of BR-C is determined by its interaction with RACK1. This novel finding will be helpful for further deciphering the mechanism underlying the role of BR-C proteins during insect development.

  2. Rate constant for the reaction SO + BrO yields SO2 + Br

    Science.gov (United States)

    Brunning, J.; Stief, L.

    1986-01-01

    The rate of the radical-radical reaction SO + BrO yields SO2 + Br has been determined at 298 K in a discharge flow system near 1 torr pressure with detection of SO and BrO via collision-free sampling mass spectrometry. The rate constant was determined using two different methods: measuring the decay of SO radicals in the presence of an excess of BrO and measuring the decay of BrO radicals in excess SO. The results from the two methods are in reasonable agreement and the simple mean of the two values gives the recommended rate constant at 298 K, k = (5.7 + or - 2.0) x 10 to the -11th cu cm/s. This represents the first determination of this rate constant and it is consistent with a previously derived lower limit based on SO2 formation. Comparison is made with other radical-radical reactions involving SO or BrO. The reaction SO + BrO yields SO2 + Br is of interest for models of the upper atmosphere of the earth and provides a potential coupling between atmospheric sulfur and bromine chemistry.

  3. Systematic hardness measurements on CsClxBr (and NH4ClxBr ...

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Bulletin of Materials Science; Volume 25; Issue 1. Systematic hardness measurements on CsClBr(1–x) and NH4ClBr(1–x) mixed crystals. K G Subhadra E Balaiah D B Sirdeshmukh. Mechanical Properties Volume 25 Issue 1 February 2002 pp 31- ...

  4. Optical properties of Pb2 -based aggregated phases in CsBr Thin film and single crystal matrices

    Science.gov (United States)

    Nikl, M.; Nitsch, K.; Mihokova, E.; Polak, K.; Fabeni, P.; Pazzi, G. P.; Gurioli, M.; Phani, R.; Santucci, S.; Scacco, A.; Somma, F.

    Emission characteristics of CsPbBr3 and Cs4PbBr6 aggregates in CsBr bulk and thin film matrices are reported. The emission of the former aggregated phase is peaking about 520-560 nm. It shows small Stokes shift (50 meV) related to narrow free exciton emission line of sub-nanosecond decay times. Quantum size effect was evidenced for the aggregates of 6-7 nm in diameter. The Cs4PbBr6 aggregates show emission peak at 375 nm and overall emission characteristics are similar to those of KBr: Pb, which is explained by very close local arrangement of emission centres-(PbBr6)4- octahedra-in both structures.

  5. R and D on fuzzy control applications to the BR1 research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, D.; Li, X. [Nuclear Research Center, Mol (Belgium)

    1998-12-31

    Fuzzy control applications in nuclear reactor operations present a tremendous challenge. The main reason for this is the public awareness of the risks of nuclear industry and the very strict safety regulations in force for nuclear power plants. The very same regulations prevent a researcher from quickly introducing novel fuzzy-logic methods into this field. On the other hand, the application of fuzzy logic has, despite the ominous sound of the word `fuzzy` to nuclear engineers, a number of very desirable advantages over classical methods, e.g., its robustness and the capability to include human experience into the controller. In this paper we report an on-going R and D project for controlling the power level of the Belgian Nuclear Reactor 1 (BR1) at the Belgian Nuclear Research Centre (SCK.CEN). The project started in 1995 and aims to investigate the added value of fuzzy control for nuclear reactors. We first review some relevant literature on fuzzy logic control in nuclear reactors, then present the state-of-the-art of the BR1 project. After experimenting fuzzy logic control under off-line tests at the BR1 reactor, we now foresee a new development for a closed-loop fuzzy control as an on-line operation of the BR1 reactor. Finally, we present the new development for a closed-loop fuzzy logic control at BR1 with an understanding of the safety requirements for this real fuzzy logic control application in nuclear rectors. (author) 18 refs.

  6. The role of Br2 and BrCl in surface ozone destruction at polar sunrise.

    Science.gov (United States)

    Foster, K L; Plastridge, R A; Bottenheim, J W; Shepson, P B; Finlayson-Pitts, B J; Spicer, C W

    2001-01-19

    Bromine atoms are believed to play a central role in the depletion of surface-level ozone in the Arctic at polar sunrise. Br2, BrCl, and HOBr have been hypothesized as bromine atom precursors, and there is evidence for chlorine atom precursors as well, but these species have not been measured directly. We report here measurements of Br2, BrCl, and Cl2 made using atmospheric pressure chemical ionization-mass spectrometry at Alert, Nunavut, Canada. In addition to Br2 at mixing ratios up to approximately 25 parts per trillion, BrCl was found at levels as high as approximately 35 parts per trillion. Molecular chlorine was not observed, implying that BrCl is the dominant source of chlorine atoms during polar sunrise, consistent with recent modeling studies. Similar formation of bromine compounds and tropospheric ozone destruction may also occur at mid-latitudes but may not be as apparent owing to more efficient mixing in the boundary layer.

  7. Alkaline hydrothermal treatment of brominated high impact polystyrene (HIPS-Br) for bromine and bromine-free plastic recovery.

    Science.gov (United States)

    Brebu, Mihai; Bhaskar, Thallada; Muto, Akinori; Sakata, Yusaku

    2006-08-01

    A method to recover both Br and Br-free plastic from brominated flame retardant high impact polystyrene (HIPS-Br) was proposed. HIPS-Br containing 15% Br was treated in autoclave at 280 degrees C using water or KOH solution of various amounts and concentrations. Hydrothermal treatment (30 ml water) leads to 90% debromination of 1g HIPS-Br but plastic is strongly degraded and could not be recovered. Alkaline hydrothermal treatment (45 ml or 60 ml KOH 1M) showed similar debromination for up to 12 g HIPS-Br and plastic was recovered as pellets with molecular weight distribution close to that of the initial material. Debromination occurs at melt plastic/KOH solution interface when liquid/vapour equilibrium is attained inside autoclave (280 degrees C and 7 MPa in our experimental conditions) and depends on the plastic amount/KOH volume ratio. The antimony oxide synergist from HIPS-Br remains in recovered plastic during treatment. A pictorial imagination of the proposed debromination process is presented.

  8. Biological signatures in clumped isotopes of O2

    Science.gov (United States)

    Yeung, Laurence Y.; Ash, Jeanine L.; Young, Edward D.

    2015-04-01

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of “clumped” isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in 18O18O and 17O18O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling.

  9. Postsynthesis Transformation of Insulating Cs4PbBr6 Nanocrystals into Bright Perovskite CsPbBr3 through Physical and Chemical Extraction of CsBr

    OpenAIRE

    Palazon, Francisco; Urso, Carmine; De Trizio, Luca; Akkerman, Quinten; Marras, Sergio; Locardi, Federico; Nelli, Ilaria; Ferretti, Maurizio; Prato, Mirko; Manna, Liberato

    2017-01-01

    Perovskite-related Cs4PbBr6 nanocrystals present a “zero-dimensional” crystalline structure where adjacent [PbBr6]4– octahedra do not share any corners. We show in this work that these nanocrystals can be converted into “three-dimensional” CsPbBr3 perovskites by extraction of CsBr. This conversion drastically changes the optoelectronic properties of the nanocrystals that become highly photoluminescent. The extraction of CsBr can be achieved either by thermal annealing (physical approach) or b...

  10. Elamusturundus: riigi brändimine ja Eesti bränd / Siiri Same

    Index Scriptorium Estoniae

    Same, Siiri

    2015-01-01

    Artikli autor oma 2015. a. Tallinna Tehnikaülikoolis kaitstud doktoritööst "Conceptualization of experience marketing and country branding from a marketing management perspective" ("Elamusturunduse ja riigi brändimise kontseptualiseerimine turunduse juhtimise vaatenurgast")

  11. $^{80m}$Br/$^{80}$Br a new electron-$\\gamma$ - PAC Probe

    CERN Document Server

    Correia, J G; Araújo, J P; Marques, J G; Soares, J C; Melo, A A

    2001-01-01

    Conversion electron-$\\gamma$ PAC measurements of the 49 keV - 37 keV cascade in $^{80}$Br through the intermediate 2$^{-}$ state with T$_{1/2}$=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF$_{2}$ scintillation detectors. The parent $^{80m}$Br activity with half-life of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and the magnetic moment of the 2$^{-}$ state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained.

  12. $^{80}$Br $^{80}$Br-a new electron-gamma PAC probe

    CERN Document Server

    Correia, J G; Araújo, J P; Marques, J G; Soares, J C; Melo, A A

    2001-01-01

    Conversion electron-gamma PAC measurements of the 49-37 keV cascade in /sup 80/Br through the intermediate 2/sup -/ state with T/sub 1/2 /=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF/sub 2/ scintillation detectors. The parent /sup 80m/Br activity with a halflife of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and the magnetic moment of the 2/sup -/ state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained. (7 refs).

  13. {sup 80m}Br/{sup 80}Br - A New Electron-Gamma PAC Probe

    Energy Technology Data Exchange (ETDEWEB)

    Correia, J. G.; Haas, H. [CERN, EP Division (Switzerland); Araujo, J. P. [IFIMUP, Fac. Ciencias (Portugal); Marques, J. G.; Soares, J. C. [Inst. Tecnologico e Nuclear (Portugal); Melo, A. A. [CFNUL (Portugal)

    2001-11-15

    Conversion electron-gamma PAC measurements of the 49-37 keV cascade in {sup 80}Br through the intermediate 2{sup -} state with T{sub 1/2}=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF{sub 2} scintillation detectors. The parent {sup 80m}Br activity with a halflife of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and the magnetic moment of the 2{sup -} state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained.

  14. Stable isotope fractionation concepts for characterizing biotransformation of organohalides.

    Science.gov (United States)

    Nijenhuis, Ivonne; Richnow, Hans H

    2016-10-01

    Recent development allows multi-element compound-specific isotope analysis of D, 13C, 37Cl and 81Br for characterizing the degradation pathways of halogenated organic substances in the environment. The apparent kinetic isotope effect (AKIE) obtained in (bio)degradation experiments yields information on the chemical mechanism of the bond cleavage. In biochemical reactions, rate limitation such as uptake into cells, substrate transport in cells and binding to enzymes as well as equilibrium isotope effects (EIE) are modifying the observed isotope fractionation associated with the bond cleavage reactions, thus, complicating mechanistic interpretation of isotope effect. One way for improved analysis of bond cleavage reactions by isotope effects reactions is the combination of isotope effects from two or more elements forming the reactive organic moieties where bond change reaction takes place as indicator. A further option is the combination of enantiomeric with isotope fractionation as complementary indicator for enzymatic bond cleavage reaction governing biodegradation. Finally an interesting concept with large potential for elucidation of the biochemical reaction mechanisms of biological dehalogenation may be quantum mechanical/molecular mechanical (QM/MM) modelling in combination with experimental multi-element isotope analysis, thus merging quantum chemical theory with experimental observation. Copyright © 2016. Published by Elsevier Ltd.

  15. The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

    Directory of Open Access Journals (Sweden)

    A. M. Batenburg

    2012-05-01

    very D-depleted H2 in the wet season may contribute to this phenomenon. <br>> Some of the samples have very high χ(H2 and very low δD values, which indicates a pollution effect. Aircraft engine exhaust plumes are a suspected cause, since the effect mostly occurs in samples collected close to airports, but no similar signals are found in other chemical tracers to support this. The isotopic source signature of the H2 pollution seems to be on the low end of the signature for fossil fuel burning.

  16. Influences of organic cation and hydrochloric acid additive on the morphology and photoluminescence of HC(NH2)2PbBr3 films

    Science.gov (United States)

    Yan, Jun; Chen, Yunlin; Wang, Ji; Zhang, Ao; Zhang, Bing

    2017-11-01

    The hydrohalic acid additives have been used in perovskite thin films to improve the film morphology and optical properties. However, our study demonstrated that the hydrochloric acid (HCl) additive greatly improved the surface coverage but lowered the photoluminescence (PL) emission intensities of HC(NH2)2PbBr3 (HC(NH2)2 = FA) films. The effects of organic cation and hydrochloric acid additive on the morphology and photoluminescence of FAPbBr3 films were investigated. We found that FAPbBr3 films prepared with HCl additive in low FABr concentration environment displayed good film quality but weak PL emission intensity. The optical properties of FAPbBr3 films have close relationship with FABr concentration. The optical absorption edge of FAPbBr3 showed a blue shift with increasing the FABr concentration. The strong PL emission intensities of FAPbBr3 can be obtained from the solutions with high FABr concentration.

  17. On the evolution of Dipodium R. Br.

    OpenAIRE

    Peter O'byrne

    2014-01-01

    Dipodium R. Br. (Orchidaceae), a genus of ca. 38 species, should be divided into an Australasian clade and a Malesian clade, based on morphological and geographic evidences. Dipodium section Dipodium and section Leopardanthus (Blume) O. Kuntze are re-defined to accommodate this change. An evolutionary scenario that explains this division is proposed. The lack of diversity of floral structure in the genus is probably caused by pollinator-specificity, while the diversity of plant form may be du...

  18. Crystal-chemistry insight into the photocatalytic activity of BiOCl x Br1- x nanoplate solid solutions

    Science.gov (United States)

    Xu, Huan-Yan; Han, Xu; Tan, Qu; Wu, Ke-Jia; Qi, Shu-Yan

    2017-06-01

    In this study, a facile alcoholysis method was developed to synthesize BiOCl x Br1- x nanoplates at room temperature and atmospheric pressure. In this route, strong acid or alkaline environment was absolutely avoided to realize the high exposure of {001} crystal facets. The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOCl x Br1- x products belonged to a group of solid solutions. The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images. Interestingly, as the Br content increased, band gaps of BiOCl x Br1- x solid solutions gradually decreased. The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCl0.5Br0.5 had the best photocatalytic activity. From the viewpoint of crystal chemistry, the photocatalytic activity of BiOCl x Br1- x solid solutions was closely related with the exposure amount of {001} facets, interlayer spacing of (001) plane and energy-level position of valence band.

  19. SWING - The Stable Water Isotope Intercomparison Group

    Science.gov (United States)

    Werner, M.; Barras, V.; Brown, J.; Gourcy, L.; Henderson-Sellers, A.; Hoffmann, G.; Ichiyanagi, K.; Kelley, M.; Noone, D.; Roads, J.; Schmidt, G.; Sturm, K.; Tindall, J.; Valdes, P.; Yoshimura, K.; Zakharov, V.

    2004-12-01

    For more than four decades the isotopic composition of water stored in various archives (e.g. ice cores, ground water) has been used to study changes in the hydrological cycle on timescales from glacial-interglacial to short term variations. However, the interpretation of isotopic variations in terms of climate change is often handicapped by a lack of other relevant observational climate parameters (e.g. temperature, relative humidity, precipitation) both in space and time. Modeling the isotopic composition of water within the hydrological cycle of general circulation models (GCM) may help to overcome this deficit on available climate data. Isotope GCMs simulate the 18O/16O (and/or 2H/1H) relation as an independent quantity within a closed "model world" where all other relevant climate parameters are known, too. This enables an improved analysis of (simulated) isotope variability in terms of climate change and during the last decade several state-of-the-art GCM models (GISS, ECHAM, LMD, GENESIS and others) have been enhanced by the capability to simulate the atmospheric and/or ocean cycle of H218O and 1H2H16O. To ensure isotope GCM reliability, any isotope GCM simulation must pass a rigorous comparison of simulated versus observed isotope data (model-data-intercomparison). In addition, artifacts in isotope simulations based on a specific GCM model parameterization or set-up have to be identified by comparing simulation results of several different isotope GCMs (model-model intercomparison). In our presentation we will give an overview and first results of the SWING project, founded in 2004. This initiative serves as a community platform for experts from the various isotope research groups and has the following objectives: (1) enable an overview about ongoing isotope GCM modeling capabilities; (2) define and perform future common GCM isotope simulation experiments of the various research groups; (3) identify the most important need of new observational isotope data

  20. Octadecabromidobis(dicarbidodecadysprosium, [Dy10Br18(C22

    Directory of Open Access Journals (Sweden)

    Kathrin Daub

    2008-01-01

    Full Text Available Single crystals of [Dy10Br18(C22] were obtained during the reaction of DyBr3 with dysprosium metal and graphite in a sealed tantalum container. In the crystal structure, the Dy atoms form dimers of edge-sharing octahedra, each encapsulating a C2 unit. The metal atoms are surrounded by Br atoms above the cluster edges and vertices, respectively. The dimers are connected to each other by Br atoms, leading to a three-dimensional network. [Dy10Br18(C22] is isotypic with its iodido analogue [Dy10I18(C22].

  1. Isotopic evidence for multiple contributions to felsic magma chambers

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Wiebe, R.A.; Krogstad, E.J.

    2007-01-01

    with identical isotopic compositions to more mafic dikes suggest that closed system fractionation may be occurring in deeper level chambers prior to injection to shallower levels. The granitic portion of the pluton has the highest Nd isotopic composition (eNd=+3.0) of plutons in the region whereas the mafic...

  2. Crystal structure, hydrogen bonding, and sup 8 sup 1 Br NQR of low-temperature phase of 4-aminopyridinium tetrabromoantimonate (3)

    CERN Document Server

    Hashimoto, M; Fuess, H; Svoboda, I; Ehrenberg, H

    2003-01-01

    The crystal structure of the low-temperature phase (LTP) of the title compound was determined at 220 K (monoclinic, P2 sub 1 sub / sub c). The 4-aminopyridinium cations (4-NH sub 2 C sub 5 H sub 4 NH sup +) were found to be ordered in LTP, while being severely disordered in the room-temperature phase (monoclinic, C2/c). The tetrabromoantimonate anions (SbBr sub 4 sup -) were incorporated into the infinite polyanion chains of irregular SbBr sub 6 octahedra with two-edges sharing. The trans-Br-Sb-Br moiety in the SbBr sub 4 sup - anion was approximately symmetric differing from the asymmetric Br-Sb centre dot centre dot centre dot Br moiety found in LTP of pyridinium tetrabromoantimonate (3). The N-H moieties in both of the pyridine ring and the amino (-NH sub 2) group participate in the formation of N-H centre dot centre dot centre dot Br hydrogen bonds. It was shown that the sup 8 sup 1 Br NQR spectrum of LTP is closely related to the anion structure and the hydrogen bonds. The distinctive anion structures, a...

  3. Iron isotope systematics of the Skaergaard intrusion

    DEFF Research Database (Denmark)

    Lesher, Charles; Lundstrom, C.C.; Barfod, Gry

    crystallization on non-traditional stable isotope systems, particularly iron. FeTi oxide minerals (titanomagnetite and ilmenite) appear after ~60% of the magma had solidified. This was a significant event affecting the liquid line of descent and potentially accompanied by iron isotope fractionation. Here we...... report the results of a broad study of the iron isotope compositions of gabbros within the layered and upper border series of the Skaergaard intrusion, pegmatite and granophyre associated with these gabbroic rocks, and the sandwich horizon thought to represent the product of extreme differentiation and....... Forward modeling of closed system fractional crystallization constrained by cumulate volumes, whole rock and mineral compositions, mineral modes and independent constraints on Fe isotope fractionation factors account for the stratigraphic relations, except during the final stages of differentiation...

  4. Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3

    Science.gov (United States)

    2017-01-01

    Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr3, its synthesis can also yield nanocrystals of Cs4PbBr6 and the properties of the two are easily confused. Here, we investigate in detail the optical characteristics of simultaneously synthesized green-emitting CsPbBr3 and insulating Cs4PbBr6 nanocrystals. We demonstrate that, in this case, the two materials inevitably hybridize, forming nanoparticles with a spherical shape. The actual amount of these Cs4PbBr6 nanocrystals and nanohybrids increases for synthesis at lower temperatures, i.e., the condition typically used for the development of perovskite CsPbBr3 nanocrystals with smaller sizes. We use state-of-the-art electron energy loss spectroscopy to characterize nanoparticles at the single object level. This method allows distinguishing between optical characteristics of a pure Cs4PbBr6 and CsPbBr3 nanocrystal and their nanohybrid. In this way, we resolve some of the recent misconceptions concerning possible visible absorption and emission of Cs4PbBr6. Our method provides detailed structural characterization, and combined with modeling, we conclusively identify the nanospheres as CsPbBr3/Cs4PbBr6 hybrids. We show that the two phases are independent of each other’s presence and merge symbiotically. Herein, the optical characteristics of the parent materials are preserved, allowing for an increased absorption in the UV due to Cs4PbBr6, accompanied by the distinctive efficient green emission resulting from CsPbBr3. PMID:28919935

  5. Postsynthesis Transformation of Insulating Cs4PbBr6 Nanocrystals into Bright Perovskite CsPbBr3 through Physical and Chemical Extraction of CsBr

    Science.gov (United States)

    2017-01-01

    Perovskite-related Cs4PbBr6 nanocrystals present a “zero-dimensional” crystalline structure where adjacent [PbBr6]4– octahedra do not share any corners. We show in this work that these nanocrystals can be converted into “three-dimensional” CsPbBr3 perovskites by extraction of CsBr. This conversion drastically changes the optoelectronic properties of the nanocrystals that become highly photoluminescent. The extraction of CsBr can be achieved either by thermal annealing (physical approach) or by chemical reaction with Prussian Blue (chemical approach). The former approach can be simply carried out on a dried film without addition of any chemicals but does not yield a full transformation. Instead, reaction with Prussian Blue in solution achieves a full transformation into the perovskite phase. This transformation was also verified on the iodide counterpart (Cs4PbI6). PMID:29285525

  6. Ozone Depletion Potential of CH3Br. Appendix H

    Science.gov (United States)

    Ko, Malcolm K. W.; Sze, Nien Dak; Scott, Courtney; Rodriguez, Jose M.; Weisenstein, Debra K.; Sander, Stanley P.

    1998-01-01

    The ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model-calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + HO2, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrONO2, and the heterogeneous conversion of BrONO2 to HOBr and HNO3 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model-calculated concentration of HBr (approx. 0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about 1 pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + HO2. Although the evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + HO2.

  7. METHOD OF ISOTOPE CONCENTRATION

    Science.gov (United States)

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  8. Enhanced tropospheric BrO over Antarctic sea ice in mid winter observed by MAX-DOAS on board the research vessel Polarstern

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-06-01

    Full Text Available We present Multi AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS observations of tropospheric BrO carried out on board the German research vessel Polarstern during the Antarctic winter 2006. Polarstern entered the area of first year sea ice around Antarctica on 24 June 2006 and stayed within this area until 15 August 2006. For the period when the ship cruised inside the first year sea ice belt, enhanced BrO concentrations were almost continuously observed. Outside the first year sea ice belt, typically low BrO concentrations were found. Based on back trajectory calculations we find a positive correlation between the observed BrO differential slant column densities (ΔSCDs and the duration for which the air masses had been in contact with the sea ice surface prior to the measurement. While we can not completely rule out that in several cases the highest BrO concentrations might be located close to the ground, our observations indicate that the maximum BrO concentrations might typically exist in a (possibly extended layer around the upper edge of the boundary layer. Besides the effect of a decreasing pH of sea salt aerosol with altitude and therefore an increase of BrO with height, this finding might be also related to vertical mixing of air from the free troposphere with the boundary layer, probably caused by convection over the warm ocean surface at polynyas and cracks in the ice. Strong vertical gradients of BrO and O3 could also explain why we found enhanced BrO levels almost continuously for the observations within the sea ice. Based on our estimated BrO profiles we derive BrO mixing ratios of several ten ppt, which is slightly higher than many existing observations. Our observations indicate that enhanced BrO concentrations around Antarctica exist about one month earlier than observed by satellite instruments. From detailed radiative transfer simulations we find that MAX-DOAS observations are up to about one order of

  9. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M.E.; Krol, M.C.; Hofmann, M.E.G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of

  10. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.|info:eu-repo/dai/nl/304838233; Popa, M. E.|info:eu-repo/dai/nl/375806407; Krol, M. C.|info:eu-repo/dai/nl/078760410; Hofmann, M. E. G.|info:eu-repo/dai/nl/374642907

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a

  11. Discharge flow kinetic study of the reactions of NO sub 3 with Br, BrO, HBr, and HCl

    Energy Technology Data Exchange (ETDEWEB)

    Mellouki, A.; Poulet, G.; Le Bras, G. (C.N.R.S., Orleans (France)); Singer, R.; Burrows, J.P.; Moortgat, G.K. (Max-Planck Institut fuer Chemie, Mainz (Germany, F.R.))

    1989-11-30

    The reactions of NO{sub 3} with Br, BrO, HBr, and HCl have been studied at 298 K by using the discharge-flow EPR method. In the study of the reactions of NO{sub 3} with Br and BrO, where NO{sub 3} and Br or BrO were flowed separately in the presence of excess NO{sub 3}, the following rate constants were found: k{sub 1} = (1.6 {plus minus} 0.7) {times} 10{sup {minus}11} for NO{sub 3} + Br {yields} NO{sub 2} + BrO (1) and 0.3 {times} 10{sup {minus}12} {le} k{sub 3} {le} 3 {times} 10{sup {minus}12} for NO{sub 3} + BrO {yields} Br + NO{sub 2} + O{sub 2} (3). Units are cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. For the reactions NO{sub 3} + HCl {yields} products (6) and NO{sub 3} + HBr {yields} products (7), the upper limits k{sub 6} {le} 5 {times} 10{sup {minus}17} and k{sub 7} {le} 1 {times} 10{sup {minus}16} were obtained.

  12. Groundwater and river baseline quality using major, trace elements, organic carbon and Sr-Pb-O isotopes in a Mediterranean catchment: The case of the Lower Var Valley (south-eastern France)

    Science.gov (United States)

    Potot, Cécile; Féraud, Gilbert; Schärer, Urs; Barats, Aurélie; Durrieu, Gaël; Le Poupon, Christophe; Travi, Yves; Simler, Roland

    2012-11-01

    SummaryDissolved trace and major elements, organic carbon and Pb-Sr-O isotopes have been investigated in surface and groundwater of the Var River Valley (SE France), including alluvial, conglomerate and limestone aquifers, as well as surface water. Boxplots and cumulative frequency distribution diagrams define chemical characteristics of each water group and distinguish between natural and anthropogenic range of concentrations. Low concentration of trace elements, statistical analysis of data and Pb isotopic ratios demonstrate that the measured baseline quality is close to the natural background, mainly influenced by water/rock interaction. Pb and Sr isotopes evidence specific primitive end members, buffering these two elements through leaching late Paleozoic rocks, strongly depleted in U and Rb since their formation. Arsenic undergoes geochemical processes such as sorption on clay minerals of the alluvial deposits. Sr isotopic ratios and high SO42-, Sr and Li contents show that Permo-Triassic sediments including evaporites strongly imprint surface waters and alluvial groundwaters. Limestone and conglomerate aquifers are mainly influenced by carbonate minerals, but may be locally affected by evaporite dissolution. High dissolved silica is also specific to conglomerate groundwaters. Limestone and conglomerate groundwaters are characterised by low and heterogeneous trace element compositions that may result from various residence times and rock compositions related to different sampling depth. Even if water quality is generally good for most of the investigated elements, pollution by agricultural activity (fertilisers and pesticides) in the alluvial and some limestone groundwaters has been demonstrated by high NO3- and Br- contents. Br- is suspected to originate from methyl bromide fertiliser. In conglomerate aquifers, NO3- contents may reach high levels, probably due to both agriculture and residential waste pollution. Despite the industrialization in the Low Var

  13. Brüssel Euroopa pealinnaks? / Ülar Mark

    Index Scriptorium Estoniae

    Mark, Ülar, 1968-

    2009-01-01

    Brüsseli Euroopa kvartali planeerimisvõistlusest, mille peakorraldaja oli Brüsseli pealinna piirkond koos Brüsseli linna ja Euroopa Komisjoniga. Eestist osales žüriis arhitekt Ülar Mark. Meeskonna Atelier Christian de Portzamparc võidutööst ja teiste teise vooru pääsenud nelja meeskonna (JDS / Julien De Smedt Architects, OMA / Office for Metropolitan Architecture, Xaveer De Geyter Architect, Fletcher Priest Architects) töödest

  14. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  15. Hurtigste versus mest brændstoføkonomiske ruter

    DEFF Research Database (Denmark)

    Andersen, Ove; Krogh, Benjamin Bjerre; Lahrmann, Harry

    2013-01-01

    Der er stort fokus på at forbedre brændstoføkonomien i transportbranchen generelt. I denne artikel anvendes brændstoftallene fra Controller Area Network Bus (CANBus) kombineret med GPS data til at skabe et digitalt vejkort, hvor det er muligt at sammenligne de hurtigste ruter med de mest...... brændstoføkonomiske ruter. Kortet er baseret på ca. 100 millioner CANBus observationer og ca. 2,1 milliarder GPS observationer. Hovedkonklusionen er, at CANBus data kan anvendes til at estimere brændstofforbruget for en rute. Sammenlignet med estimering af køretider er det mere kompliceret at estimere...

  16. Product vibrational distributions in CH 3Br photodissociation

    Science.gov (United States)

    Escure, Christelle; Leininger, Thierry; Lepetit, Bruno

    2009-09-01

    We performed a theoretical study of the photodissociation dynamics of CH 3Br in the A˜ band using a wavepacket propagation technique on coupled ab initio potential energy surfaces corresponding to the 3Q 1 and 1Q 1 states correlated at large distance with the Br ground spin-orbit state, as well as the 3Q 0 and 4E states correlated to the excited one. The methyl umbrella vibrational product state distributions are found in very good agreement with experimental results. They are hotter for Br than for Br ∗, and this is related to the shapes of the 3Q 0 and 1Q 1 potentials.

  17. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  18. In situ Spectroscopy of Solid-State Chemical Reaction in PbBr2-Deposited CsBr Crystals

    Science.gov (United States)

    Kondo, Shin-ichi; Matsunaga, Toshihiro; Saito, Tadaaki; Asada, Hiroshi

    2003-09-01

    It is possible to measure the fundamental optical absorption spectra of CsPbBr3 and Cs4PbBr6, whose stability is predicted by the study of phase diagram in the binary system CsBr-PbBr2, by means of in situ optical absorption and reflection spectroscopy of thermally induced solid-state chemical reaction in PbBr2-deposited CsBr crystals. On heavy annealing of the crystals, the Pb2+ ions are uniformly dispersed in the crystal matrix. The present experiment provides a novel method for measuring intrinsic optical absorption of ternary metal halides and also for in situ monitoring of doping metal halide crystal with impurities (metal ions or halogen ions).

  19. Determination of nuclear cross-section of 81Br (n,,,) Br82 reaction by ...

    African Journals Online (AJOL)

    ... flux of 4.2 x 1013 n cm-2 s-1. The BaBr2 was chemically processed and measured as Hydrogen Bromide (HBr82). The value of nuclear cross-section was determined to be 2.1 0.2 barns, which falls within the range of values as previously reported elsewhere. (Journal of Applied Science and Technology: 2001 6(1-2): 4-6) ...

  20. Exploring Polaronic, Excitonic Structures and Luminescence in Cs4PbBr6/CsPbBr3.

    Science.gov (United States)

    Kang, Byungkyun; Biswas, Koushik

    2018-02-15

    Among the important family of halide perovskites, one particular case of all-inorganic, 0-D Cs 4 PbBr 6 and 3-D CsPbBr 3 -based nanostructures and thin films is witnessing intense activity due to ultrafast luminescence with high quantum yield. To understand their emissive behavior, we use hybrid density functional calculations to first compare the ground-state electronic structure of the two prospective compounds. The dispersive band edges of CsPbBr 3 do not support self-trapped carriers, which agrees with reports of weak exciton binding energy and high photocurrent. The larger gap 0-D material Cs 4 PbBr 6 , however, reveals polaronic and excitonic features. We show that those lattice-coupled carriers are likely responsible for observed ultraviolet emission around ∼375 nm, reported in bulk Cs 4 PbBr 6 and Cs 4 PbBr 6 /CsPbBr 3 composites. Ionization potential calculations and estimates of type-I band alignment support the notion of quantum confinement leading to fast, green emission from CsPbBr 3 nanostructures embedded in Cs 4 PbBr 6 .

  1. Synthesis and infrared characterization of Br-HBr and Br-DBr entrance channel complexes in solid parahydrogen.

    Science.gov (United States)

    Kettwich, Sharon C; Pinelo, Laura F; Anderson, David T

    2008-09-28

    We report high resolution vibrational spectra in the HBr (2560 cm(-1)) and DBr (1840 cm(-1)) stretching regions for Br-HBr and Br-DBr entrance channel complexes isolated in solid parahydrogen (pH2). The Br-HBr complexes are generated by synthesizing solid pH2 crystals doped with trace amounts of HBr/Br2 mixtures followed by 355 nm in situ photodissociation of Br2 to form Br atoms. After photolysis is complete, the solid is warmed from 2 to 4.3 K resulting in the irreversible formation of Br-HBr complexes. The large 36.63 cm(-1) HBr monomer-to-complex induced vibrational shift to lower energy measured in these studies is consistent with the linear Br-HBr hydrogen bonded structure predicted from theory. The 0.02 cm(-1) Br-HBr absorption linewidths indicate a 1 ns vibrational excited state lifetime for these entrance channel complexes in solid pH2.

  2. Elimination of nonspecific radioactivity from [{sup 76}Br]bromide in PET study with [{sup 76}Br]bromodeoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Li Lu; Bergstroem, Mats E-mail: Mats.Bergstroem@pet.uu.se; Fasth, Karl-Johan; Wu Feng; Eriksson, Barbro; Laangstroem, Bengt

    1999-10-01

    [{sup 76}Br]Bromodeoxyuridine ([{sup 76}Br]BrdU) might allow a determination of proliferation in vivo using positron emission tomography (PET), but only with consideration of organ nonspecific radioactivity constituted by [{sup 76}Br]bromide. A first study assessed the potential of diuretics to eliminate [{sup 76}Br]bromide. [{sup 76}Br]Bromide was injected in the vein of rats and different diuretic combinations were given. Urine was collected and radioactivity measured. Torasemide plus sodium chloride gave better {sup 76}Br elimination than the other diuretics. In a second experiment, rats were given [{sup 76}Br]BrdU. After the radioactivity injection, the rats of the treatment group were given torasemide plus NaCl. At 44 h after the radioactivity injection, the radioactivity concentration and the fraction incorporated into DNA were measured in different organs. Using diuretics, the elimination of [{sup 76}Br]bromide was increased. The radioactivity decreased 30-50% in most of the organs but the highest radioactivity uptake was found in the organs with more active DNA synthesis. This method may facilitate the use of [{sup 76}Br]BrdU as a tracer for DNA synthesis using PET.

  3. Visible light photocatalytic activity enhancement and mechanism of AgBr/Ag3PO4 hybrids for degradation of methyl orange.

    Science.gov (United States)

    Cao, Jing; Luo, Bangde; Lin, Haili; Xu, Benyan; Chen, Shifu

    2012-05-30

    Novel AgBr/Ag(3)PO(4) hybrids were synthesized via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectroscopy (DRS). Under visible light (λ>420 nm), AgBr/Ag(3)PO(4) degraded methyl orange (MO) efficiently and displayed much higher photocatalytic activity than that of pure AgBr or Ag(3)PO(4). X-ray photoelectron spectroscopy (XPS) suggests that AgBr/Ag(3)PO(4) transformed to be Ag@AgBr/Ag(3)PO(4)@Ag system while remained good photocatalytic activity after 5 times of cycle experiments. In addition, the quenching effects of different scavengers proved that reactive OH and h(+) played the major role for the MO degradation. The photocatalytic activity enhancement of AgBr/Ag(3)PO(4) is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between AgBr and Ag(3)PO(4), as well as the good electron trapping role of Ag nanoparticles in situ formed on the surfaces of AgBr and Ag(3)PO(4) particles during the photocatalytic reaction. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Stable water isotopes in the MITgcm

    Science.gov (United States)

    Völpel, Rike; Paul, André; Krandick, Annegret; Mulitza, Stefan; Schulz, Michael

    2017-08-01

    We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm). The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM), while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite). The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model-data mismatch is also recognizable in the isotopic composition of the seawater-salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model-data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  5. Stable water isotopes in the MITgcm

    Directory of Open Access Journals (Sweden)

    R. Völpel

    2017-08-01

    Full Text Available We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm. The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM, while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite. The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model–data mismatch is also recognizable in the isotopic composition of the seawater–salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model–data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  6. On the evolution of Dipodium R. Br.

    Directory of Open Access Journals (Sweden)

    Peter O'byrne

    2014-12-01

    Full Text Available Dipodium R. Br. (Orchidaceae, a genus of ca. 38 species, should be divided into an Australasian clade and a Malesian clade, based on morphological and geographic evidences. Dipodium section Dipodium and section Leopardanthus (Blume O. Kuntze are re-defined to accommodate this change. An evolutionary scenario that explains this division is proposed. The lack of diversity of floral structure in the genus is probably caused by pollinator-specificity, while the diversity of plant form may be due to long-term environmental factors. An evolutionary explanation is suggested for the complex between Dipodium fevrellii J. J. Sm. and the hybrid D. pandanum Bailey in New Guinea. The complex in Java involving          D. pictum (Lindl. Rchb. f. and D. scandens (Bl. J. J. Sm. is discussed, and the presence of a hybrid noted. In Borneo, the complex taxonomic situation caused by repeated inter-breeding of populations is noted. 

  7. Inhibition of tumor angiogenesis by Brahma Rasayana (BR).

    Science.gov (United States)

    Thangapazham, Rajesh L; Sharma, Anuj; Gaddipati, Jaya P; Singh, Anoop K; Maheshwari, Radha K

    2006-01-01

    The current therapy for prostate cancer includes radical prostatectomy, radiation therapy and hormonal ablation. Chemotherapy also provides beneficial results for some patients with advanced prostate cancer but with several harmful side effects. Hence there is a need to identify and develop alternate therapies, which can reduce the disease progression with minimal or few side effects. Earlier studies from our laboratory have shown that a Polyherbal mixture, Brahma Rasayna (BR) rich in anti-oxidant principles has a potential to be an anti-tumor agent. BR treatment of MAT-LyLu cell inoculated Copenhagen rats resulted in a decrease of palpable tumor incidence, delay in tumor occurrence and lower mean tumor volumes. Also, a significant reduction in tumor weight and lung metastasis was observed in BR treated animals in comparison to untreated controls. In the present study, we focused to examine the effect of BR on angiogenesis and regulation of molecular markers involved in angiogenesis using in-vivo and in-vitro models. BR treatment showed a significant reduction in Factor VIII expression compared to control indicating reduced angiogenesis. BR treated tumor specimens showed a decrease in the pro-angiogenic factors like VEGF, MMP-9 and MMP-2. Methanolic extract of BR was found to inhibit the proliferation, tube formation, cell migration and attachment of HUVEC on matrigel in a dose dependant manner. These findings suggest the possible mechanism(s) of action of BR in the reduction of tumor growth and metastatic spread.

  8. Corrosion inhibition performance of a ionic liquid surfactant Br

    Directory of Open Access Journals (Sweden)

    Jing LIU

    2016-02-01

    Full Text Available In order to study the novel green organic mercury-substituting inhibitors, the ionic liquid surfactant 1-methyl-3-dodecyl imidazole bromide ( Br is synthesized with N-methyl imidazole and 1-bromodecane as raw materials. The corrosion inhibition of Br for zinc in zinc-manganese batteries is investigated using electrochemical methods and weight loss methods. The results show that corrosion inhibition efficiency increases with the increase of the concentration of Br, and when the concentration is higher than 8×10-3 mol/L, the inhibition efficiency tends to be stable. The polarization curve shows that Br belongs to mixed-type corrosion inhibitor. The thermodynamic parameters show that Br is spontaneously adsorbed on the zinc surface, forming a monomolecular adsorption layer, which fits with Langmuir adsorption isotherm with physical and chemical adsorption mechanism.

  9. Application of dual carbon-bromine isotope analysis for investigating abiotic transformations of tribromoneopentyl alcohol (TBNPA).

    Science.gov (United States)

    Kozell, Anna; Yecheskel, Yinon; Balaban, Noa; Dror, Ishai; Halicz, Ludwik; Ronen, Zeev; Gelman, Faina

    2015-04-07

    Many of polybrominated organic compounds, used as flame retardant additives, belong to the group of persistent organic pollutants. Compound-specific isotope analysis is one of the potential analytical tools for investigating their fate in the environment. However, the isotope effects associated with transformations of brominated organic compounds are still poorly explored. In the present study, we investigated carbon and bromine isotope fractionation during degradation of tribromoneopentyl alcohol (TBNPA), one of the widely used flame retardant additives, in three different chemical processes: transformation in aqueous alkaline solution (pH 8); reductive dehalogenation by zero-valent iron nanoparticles (nZVI) in anoxic conditions; oxidative degradation by H2O2 in the presence of CuO nanoparticles (nCuO). Two-dimensional carbon-bromine isotope plots (δ(13)C/Δ(81)Br) for each reaction gave different process-dependent isotope slopes (Λ(C/Br)): 25.2 ± 2.5 for alkaline hydrolysis (pH 8); 3.8 ± 0.5 for debromination in the presence of nZVI in anoxic conditions; ∞ in the case of catalytic oxidation by H2O2 with nCuO. The obtained isotope effects for both elements were generally in agreement with the values expected for the suggested reaction mechanisms. The results of the present study support further applications of dual carbon-bromine isotope analysis as a tool for identification of reaction pathway during transformations of brominated organic compounds in the environment.

  10. Sulfur Isotope Effects of Dissimilatory Sulfite Reductase

    Directory of Open Access Journals (Sweden)

    William D. Leavitt

    2015-12-01

    Full Text Available The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR. Here we provide the only direct observation of the major (34S/32S and minor (33S/32S, 36S/32S sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB. Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in 34S/32S (hereafter, 34εDsrAB to be 15.3±2‰, 2σ. The accompanying minor isotope effect in 33S, described as 33λDsrAB, is calculated to be 0.5150±0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3 to 0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in 34εDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of 34εDsrAB is similar to the median value of experimental observations compiled from all known published work, where 34εr-p = 16.1‰ (r – p indicates reactant versus product, n = 648. This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments (34εSO4-H2S = 17.3±1.5‰ and in modern marine sediments (34εSO4-H2S = 17.3±3.8‰. Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in modern

  11. Brändikäsikirjan toteutus Yritys X:n brändin rakentamisen tueksi

    OpenAIRE

    Ahokas, Riikka

    2017-01-01

    Tämän opinnäytetyön tavoitteena oli luoda toimeksiantajayritykselle yhdenmukainen ja kilpailijoista erottuva brändi. Tarkoituksena oli siis selvittää, minkälainen brändi kuvaa yritystä parhaiten sekä eroaa riittävästi yrityksen kilpailijoista. Tämän lisäksi selvitettiin, millainen on hyvä brändikäsikirja. Toimeksiantajayrityksen on tarkoitus käyttää brändikäsikirjaa henkilöstönsä perehdytyksessä. Teoreettisessa viitekehyksessä käsitellään brändiä, sen tärkeimpiä tehtäviä sekä sen merkitys...

  12. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G. J., LLNL

    1998-06-01

    also be treated as a mostly closed system for mass balance considerations. It is the near closure of the system that permits well- constrained chemical mass balance calculations to be made. These calculations generally focus of lithogenic solutes, and therefore in our discussions of lithogenic nuclides in the paper, the concept of chemical mass balance in a nearly dosed system will play an important role. Examination of the isotopic compositions of solutes provides a better understanding of the variety of processes controlling mass balance. It is with this approach that we examined the variety of processes occurring within the catchment system, such as weathering and soil production, generation of stormflow and streamflow (hydrograph separation), movement of soil pore water, groundwater flow, and the overall processes involved with basinal water balance. In this paper, the term `nuclide` will be used when referring to a nuclear species that contains a particular number of protons and neutrons. The term is not specific to any element. The term `isotope` will be used to distinguish nuclear species of a given element (atoms with the same number of protons). That is to say, there are many nuclides in nature - for example, {sup 36}Cl, {sup 87}Sr, {sup 238}U; the element has four naturally-occurring isotopes - {sup 87}Sr, and {sup 88}Sr. This paper will first discuss the general principles that underlie the study of lithogenic and cosmogenic nuclides in hydrology, and provide references to some of the more important studies applying these principles and nuclides. We then turn in the second section to a discussion of their specific applications in catchment- scale systems. The final section of this paper discusses new directions in the application of lithogenic and cosmogenic nuclides to catchment hydrology, with some thoughts concerning possible applications that still remain unexplored.

  13. Discovery of the Indium Isotopes

    CERN Document Server

    Amos, S

    2010-01-01

    Thirty-eight indium isotopes (A = 98-135) have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  14. Equilibrium reconstruction in the TCA/Br tokamak; Reconstrucao do equilibrio no tokamak TCA/BR

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Wanderley Pires de

    1996-12-31

    The accurate and rapid determination of the Magnetohydrodynamic (MHD) equilibrium configuration in tokamaks is a subject for the magnetic confinement of the plasma. With the knowledge of characteristic plasma MHD equilibrium parameters it is possible to control the plasma position during its formation using feed-back techniques. It is also necessary an on-line analysis between successive discharges to program external parameters for the subsequent discharges. In this work it is investigated the MHD equilibrium configuration reconstruction of the TCA/BR tokamak from external magnetic measurements, using a method that is able to fast determine the main parameters of discharge. The thesis has two parts. Firstly it is presented the development of an equilibrium code that solves de Grad-Shafranov equation for the TCA/BR tokamak geometry. Secondly it is presented the MHD equilibrium reconstruction process from external magnetic field and flux measurements using the Function Parametrization FP method. this method. This method is based on the statistical analysis of a database of simulated equilibrium configurations, with the goal of obtaining a simple relationship between the parameters that characterize the equilibrium and the measurements. The results from FP are compared with conventional methods. (author) 68 refs., 31 figs., 16 tabs.

  15. La Alpaca -vaatemerkin brändäys

    OpenAIRE

    Lehtinen, Laura

    2013-01-01

    Tämä opinnäytetyö käsittelee brändin vahvistamista ja brändiohjeiston luomista vaa-tealan yritykselle La Alpacalle. La Alpaca on suomalainen vaatemerkki, joka suunnit-telee, tuottaa ja myy alpakanvillasta valmistettuja tuotteita. Materiaalin ainutlaatuisuus ja hienous ovat olleet osa yrityksen identiteettiä alusta asti. Brändin lisäksi työssä on tutkittu kaupankäynnin rakenteellista muuttumista perinteisestä myymälätoiminnasta verkkomyyntiin. Työn tavoitteena on ollut luoda materiaalin tun...

  16. Coulomb excitation of neutron-deficient polonium isotopes studied at ISOLDE

    CERN Document Server

    Neven, Michiel

    The polonium isotopes represent an interesting region of the nuclear chart having only two protons outside the Z = 82 closed shell. These isotopes have already been extensively studied theoretically and experimentally. The heavier isotopes (A > 200) seem to follow a "regular seniority-type regime" while for the lighter isotopes (A < 200) a more collective behavior is observed. Many questions remain regarding the transition between these two regimes and the configuration mixing between quantum states. Experiments in the lighter polonium isotopes point to the presence of shape coexistence, however the phenomenon is not fully understood. A Coulomb excitation study of the polonium isotopes whereby the dynamic properties are investigated can provide helpful insights in understanding the shape coexistence phenomena. In this thesis $^{202}$Po was studied via Coulomb excitation. The $^{202}$Po isotope was part of an experimental campaign in which the $^{196,198,200,206}$Po isotopes were studied as well via Coulomb...

  17. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms.

    Directory of Open Access Journals (Sweden)

    Xueshu Xie

    Full Text Available Isotopic compositions of reactants affect the rates of chemical and biochemical reactions. Usually it is assumed that heavy stable isotope enrichment leads to progressively slower reactions. Yet the effect of stable isotopes may be nonlinear, as exemplified by the "isotopic resonance" phenomenon. Since the isotopic compositions of other planets of Solar system, including Mars and Venus, are markedly different from terrestrial (e.g., deuterium content is ≈5 and ≈100 times higher, respectively, it is far from certain that terrestrial life will thrive in these isotopic conditions. Here we found that Martian deuterium content negatively affected survival of shrimp in semi-closed biosphere on a year-long time scale. Moreover, the bacterium Escherichia coli grows slower at Martian isotopic compositions and even slower at Venus's compositions. Thus, the biological impact of varying stable isotope compositions needs to be taken into account when planning interplanetary missions.

  18. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms.

    Science.gov (United States)

    Xie, Xueshu; Zubarev, Roman A

    2017-01-01

    Isotopic compositions of reactants affect the rates of chemical and biochemical reactions. Usually it is assumed that heavy stable isotope enrichment leads to progressively slower reactions. Yet the effect of stable isotopes may be nonlinear, as exemplified by the "isotopic resonance" phenomenon. Since the isotopic compositions of other planets of Solar system, including Mars and Venus, are markedly different from terrestrial (e.g., deuterium content is ≈5 and ≈100 times higher, respectively), it is far from certain that terrestrial life will thrive in these isotopic conditions. Here we found that Martian deuterium content negatively affected survival of shrimp in semi-closed biosphere on a year-long time scale. Moreover, the bacterium Escherichia coli grows slower at Martian isotopic compositions and even slower at Venus's compositions. Thus, the biological impact of varying stable isotope compositions needs to be taken into account when planning interplanetary missions.

  19. SHELL ISOTOPE GEOCHEMISTRY

    African Journals Online (AJOL)

    Valley. Although fossil specimens of this subspecies have been used in palaeoclimatic reconstruction, there have been no previous reports of living examples. Here We describe the local habitat, climate and some aspects of ecology and isotopic variation within the snail shell. If isotope data can be obtained for fossil shells, ...

  20. ICT: isotope correction toolbox.

    Science.gov (United States)

    Jungreuthmayer, Christian; Neubauer, Stefan; Mairinger, Teresa; Zanghellini, Jürgen; Hann, Stephan

    2016-01-01

    Isotope tracer experiments are an invaluable technique to analyze and study the metabolism of biological systems. However, isotope labeling experiments are often affected by naturally abundant isotopes especially in cases where mass spectrometric methods make use of derivatization. The correction of these additive interferences--in particular for complex isotopic systems--is numerically challenging and still an emerging field of research. When positional information is generated via collision-induced dissociation, even more complex calculations for isotopic interference correction are necessary. So far, no freely available tools can handle tandem mass spectrometry data. We present isotope correction toolbox, a program that corrects tandem mass isotopomer data from tandem mass spectrometry experiments. Isotope correction toolbox is written in the multi-platform programming language Perl and, therefore, can be used on all commonly available computer platforms. Source code and documentation can be freely obtained under the Artistic License or the GNU General Public License from: https://github.com/jungreuc/isotope_correction_toolbox/ {christian.jungreuthmayer@boku.ac.at,juergen.zanghellini@boku.ac.at} Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  1. A novel Br-substituted diarylethene: Synthesis, crystal structure, and solvent dependent acidichromism

    Science.gov (United States)

    Zheng, Chunhong; Fan, Congbin; Pu, Shouzhi; Chen, Bing; Chen, Ben

    2016-11-01

    A novel Br-substituted diarylethene was synthesized, and its structure has been determined by single-crystal X-ray diffraction analysis. Its photochemical property in solution, a PMMA film, and single crystalline phase was studied. In solution, the absorption maximum of its closed-ring isomer shifted dramatically to shorter wavelengths with notable color change from violet to yellow upon the stimulation of trifluoroacetic acid. Moreover, the acidichromism showed obviously solvent-dependence. With enhancement of solvent polarity, the protonation-induced absorption maxima (Δλmax) and the response time became longer.

  2. Ab initio study of the Br(2P)-HBr van der Waals complex.

    Science.gov (United States)

    Toboła, R; Chałasiński, G; Kłos, J; Szcześniak, M M

    2009-05-14

    This study reports an ab initio characterization of a prereactive van der Waals complex between an open-shell atom Br((2)P) and a closed shell molecule HBr. The three adiabatic potential surfaces 1 (2)A('), 2 (2)A('), and 1 (2)A("), which result from the splitting of degenerate P state of Br are obtained from coupled cluster calculations. The coupling between same-symmetry states is calculated by multireference configuration-interaction method. A transformation to a diabatic representation and inclusion of the spin-orbit coupling effects on the interactions are also discussed. Bound states are calculated using an adiabatic bender model. The global minimum on the lowest adiabatic potential surface corresponds to a T-shaped geometry and has a well depth of D(e)=762.5 cm(-1) at R(e)=3.22 A. A secondary minimum occurs for a hydrogen-bonded geometry with D(e)=445.3 cm(-1) at R(e)=4.24 A. Upon inclusion of spin-orbit coupling the hydrogen-bonded minimum remains at the same depth, but the T-shaped minimum washes out to less than half of its spin-free value. The lowest bound state is localized in the linear minimum. The spin-orbit coupling plays a very important role in shaping of the potential energy surfaces of Br-HBr.

  3. Oxygen isotope fractionation in double carbonates.

    Science.gov (United States)

    Zheng, Yong-Fei; Böttcher, Michael E

    2016-01-01

    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  4. Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3

    OpenAIRE

    Weerd, Chris de; Lin, Junhao; Gomez, Leyre; Fujiwara, Yasufumi; Suenaga, Kazutomo; Gregorkiewicz, Tom

    2017-01-01

    Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr3, its synthesis can also yield nanocrystals of Cs4PbBr6 and the properties of the two are easily confused. Here, we investigate in de...

  5. Elu Brüsselis - teisem kui siin / Juune Holvandus

    Index Scriptorium Estoniae

    Holvandus, Juune

    2000-01-01

    Brüsseli kesklinnas elavast noorpaarist ja nende kodust. Veronique Mägi (isa eestlane) on tõlk. Ettevõtja Frederic Flamand on õppinud antiigindust. 1996. a. elati Eestis. Inimsuhetest Eestis ja Belgias. 11 ill.

  6. GMO konverents Brüsselis / Nastja Pertsjonok

    Index Scriptorium Estoniae

    Pertsjonok, Nastja

    2007-01-01

    Brüsselis toimunud GMO-vabade piirkondade konverentsist, kus räägiti GMO-vabade piirkondade liikumisest, GMO-de lubamisest ja keelamisest ning hoiakutest nende suhtes Euroopa Liidus ja mujal maailmas

  7. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  8. Kan lignin omdannes til flydende brændstof?

    DEFF Research Database (Denmark)

    Nielsen, Joachim Bachmann; Jensen, Anders; Felby, Claus

    2015-01-01

    Ved en solvolytisk omdannelse af plantematerialet lignin til et flydende brændstof behandles det ved høj temperatur og højt tryk i et passende opløsningsmiddel. En sådan proces kan gennemføres ikke-katalytisk og være med til at skabe flydende brændsler baseret på vedvarende energikilder. Her...

  9. Saltindhold i brød og morgenmadscerealier

    DEFF Research Database (Denmark)

    Trolle, Ellen; Saxholt, Erling; Knuthsen, Pia

    2016-01-01

    Saltindholdet i hvedebrød og rugbrød på de danske supermarkedshylder er faldet fra 2009 til 2014. En tilsvarende trend er ikke registreret i brød fra bagerbutikker. Udviklingen betyder, at en større andel af industrielt fremstillede brød end bagerbrød indsamlet i 2014 overholder Nøglehulsmærkets ...... overstiger Nøglehulsmærkets saltkrav. Saltindholdet er dog faldet i forhold til tidligere....

  10. Atmospheric lifetimes and ozone depletion potentials of methyl bromide (CH3Br) and dibromomethane (CH2Br2)

    Energy Technology Data Exchange (ETDEWEB)

    Mellouki, A.; Talukdar, R.K.; Schmoltner, A.; Gierczak, T.; Mills, M.J.; Solomon, S.; Ravishankara, A.R. (NOAA, Boulder, CO (United States))

    1992-10-01

    The rate coefficients for the reactions of OH radical with CH3Br and CH2Br2 were measured as functions of temperature using the laser photolysis - laser induced fluorescence method. This data was incorporated into a semiempirical model (Solomon et al., 1992) and a 2D model to calculate the steady-state ozone depletion potentials (ODP) and atmospheri lifetimes, tau, with greatly improved accuracy as compared to earlier studies. The calculated ODPs and tau are 0.65 and 1.7 years and 0.17 and 0.41 years for CH3Br and CH2Br2, respectively, using the semiempirical model. These lifetimes agree well with those calculated using a 2D model. This study better quantifies the ODPs and tau of these species which are needed inputs for discussion of possible regulation of human emissions currently under international considerations. 29 refs.

  11. Hydrogen and oxygen isotope ratios in body water and hair: modeling isotope dynamics in nonhuman primates.

    Science.gov (United States)

    O'Grady, Shannon P; Valenzuela, Luciano O; Remien, Christopher H; Enright, Lindsey E; Jorgensen, Matthew J; Kaplan, Jay R; Wagner, Janice D; Cerling, Thure E; Ehleringer, James R

    2012-07-01

    The stable isotopic composition of drinking water, diet, and atmospheric oxygen influence the isotopic composition of body water ((2)H/(1)H, (18)O/(16)O expressed as δ(2) H and δ(18)O). In turn, body water influences the isotopic composition of organic matter in tissues, such as hair and teeth, which are often used to reconstruct historical dietary and movement patterns of animals and humans. Here, we used a nonhuman primate system (Macaca fascicularis) to test the robustness of two different mechanistic stable isotope models: a model to predict the δ(2)H and δ(18)O values of body water and a second model to predict the δ(2)H and δ(18)O values of hair. In contrast to previous human-based studies, use of nonhuman primates fed controlled diets allowed us to further constrain model parameter values and evaluate model predictions. Both models reliably predicted the δ(2)H and δ(18)O values of body water and of hair. Moreover, the isotope data allowed us to better quantify values for two critical variables in the models: the δ(2)H and δ(18)O values of gut water and the (18)O isotope fractionation associated with a carbonyl oxygen-water interaction in the gut (α(ow)). Our modeling efforts indicated that better predictions for body water and hair isotope values were achieved by making the isotopic composition of gut water approached that of body water. Additionally, the value of α(ow) was 1.0164, in close agreement with the only other previously measured observation (microbial spore cell walls), suggesting robustness of this fractionation factor across different biological systems. © 2012 Wiley Periodicals, Inc.

  12. The process of glauconitization: chemical and isotopic evidence

    Science.gov (United States)

    Stille, Peter; Clauer, Norbert

    1994-08-01

    Sequential leaching experiments were made on Recent glauconies and clay fractions of the associated mud from off-shore Africa near the estuary of the Congo River. Analyses of major/rare earth elements (REE) and Nd isotopic compositions on the resulting leachate and residue pairs allow identification of at least three important and isotopically distinct components which contributed to the glauconitization process: (1) a detrital component with relatively high 87Sr/86Sr and relatively low 143Nd/144Nd isotopic ratios; (2) a phosphate phase rich in REE and Sr with sea water Sr and Nd isotopic characteristics; (3) a component rich in organic matter and Ca with a sea water Sr isotopic signature, a relatively low Nd isotopic composition and elevated Sm/Nd ratios. This latter component probably represents the suspended organic and carbonate-rich river load. The detrital and the river components were mixed up in the muddy off-shore sediment, ingested by worms, and integrated into faecal pellets. The resulting material has Sr and Nd isotopic signatures intermediate between those of the detrital and river components, and represents the precursor of the glaucony minerals. During the subsequent dissolution-crystallization process, the glauconitic pellets remain isotopically closed to any external supply, but expulsion of Sr and Nd with increasing degree of maturation is observed without any effect on the Sr and Nd isotopic compositions. At a higher maturation stage (K2O>4.5%), the Sr and Nd isotopic compositions tend to decrease and increase, respectively, approximating the isotopic composition values of the phosphate-rich phase. Because the Sr and Nd concentrations decrease, the evolution of the glauconies toward lower Sr and higher Nd isotopic compositions can only be explained by expulsion of Sr and Nd of the detrital component with high Sr and low Nd isotopic signatures. Dissolution of the chemically unstable, wormdigested clay material from mud may be responsible for the

  13. Spatial isotopic heterogeneity during the Guttenberg isotopic carbon excursion: Mechanisms and implications for craton-wide isotope gradients

    Science.gov (United States)

    Metzger, J. G.; Fike, D. A.

    2012-12-01

    The carbon isotopic compositions of carbonate carbon (δ13Ccarb) and organic carbon (δ13Corg) in marine limestones are frequently used as paleoenvironmental proxies and as chemostratigraphic tools for aligning strata. These functions are predicated upon the assumption that isotopic variability in these strata reflects the secular variation in the marine reservoir of dissolved inorganic carbon (DIC). As such, the utility of these isotopic systems largely depends on the assumed spatial homogeneity of marine δ13CDIC. While other isotope systems such as sulfate and strontium have been shown to be extremely well mixed in the modern ocean, a 1-2‰ range in δ13CDIC exists over the entire depth and latitude range of the ocean. This variability in δ13CDIC is largely the result of differences in the local balance of organic carbon fixation and export (increasing δ13CDIC) and/or organic carbon oxidation (decreasing δ13CDIC). The preservation of such isotopic variability in the geologic record has been advocated on several occasions. In particular, previous workers have argued for an ocean-to-interior seaway isotopic gradient in δ13Ccarb, δ13Corg, and ɛNd across Laurentia during the Late Ordovician across the interval that spans the Guttenberg Isotopic Carbon Excursion (GICE). Here we examine two Late Ordovician-aged sections from Missouri, USA that contain the GICE. At first glace, our data showed high degree of stratigraphic and lateral variability. Detailed petrographic and geochemical (e.g., trace element abundance) screening reveals that the majority of the isotopic heterogeneity in our sections is the result of local syndepositional/diagenetic alteration - and not the result of primary gradients in δ13CDIC between the localities examined. Our 'least-altered' δ13Ccarb profile matches closely with previously published records from Iowa; however, sections adjacent both to our locations in Missouri and to the similar δ13Ccarb profile in Iowa are characterized by

  14. Deformation properties of lead isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tolokonnikov, S. V.; Borzov, I. N.; Lutostansky, Yu. S.; Saperstein, E. E., E-mail: saper43-7@mail.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-01-15

    The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF{sup 0} Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, {sup 180}Pb and {sup 184}Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF{sup 0} functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF{sup 0} functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron

  15. Interplay between halogen bonds and hydrogen bonds in OH/SH···HOX···HY (X = Cl, Br; Y = F, Cl, Br) complexes.

    Science.gov (United States)

    Wu, Wenjie; Zeng, Yanli; Li, Xiaoyan; Zhang, Xueying; Zheng, Shijun; Meng, Lingpeng

    2013-03-01

    The character of the cooperativity between the HOX···OH/SH halogen bond (XB) and the Y-H···(H)OX hydrogen bond (HB) in OH/SH···HOX···HY (X = Cl, Br; Y = F, Cl, Br) complexes has been investigated by means of second-order Møller-Plesset perturbation theory (MP2) calculations and "quantum theory of atoms in molecules" (QTAIM) studies. The geometries of the complexes have been determined from the most negative electrostatic potentials (V (S,min)) and the most positive electrostatic potentials (V (S,max)) on the electron density contours of the individual species. The greater the V (S,max) values of HY, the larger the interaction energies of halogen-bonded HOX···OH/SH in the termolecular complexes, indicating that the ability of cooperative effect of hydrogen bond on halogen bond are determined by V (S,max) of HY. The interaction energies, binding distances, infrared vibrational frequencies, and electron densities ρ at the BCPs of the hydrogen bonds and halogen bonds prove that there is positive cooperativity between these bonds. The potentiation of hydrogen bonds on halogen bonds is greater than that of halogen bonds on hydrogen bonds. QTAIM studies have shown that the halogen bonds and hydrogen bonds are closed-shell noncovalent interactions, and both have greater electrostatic character in the termolecular species compared with the bimolecular species.

  16. Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

    Science.gov (United States)

    Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

    2017-07-01

    Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

  17. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  18. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  19. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  20. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    ) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3....... The simulation of Greenland isotopes is tested for the isotope-enabled model CAM5. Here the importance of model resolution is investigated. A positive bias of 6-10 ‰ is found for the annual mean δ18O on the central part of the Greenland Ice Sheet. The amplitude of the seasonal cycle of Greenland δ18O is highly...

  1. Finding the Missing Stratospheric Br(sub y): A Global Modeling Study of CHBr3 and CH2Br2

    Science.gov (United States)

    Liang, Q.; Stolarski, R. S.; Kawa, S. R.; Nielsen, J. E.; Douglass, A. R.; Rodriguez, J. M.; Blake, D. R.; Atlas, E. L.; Ott, L. E.

    2010-01-01

    Recent in situ and satellite measurements suggest a contribution of 5 pptv to stratospheric inorganic bromine from short-lived bromocarbons. We conduct a modeling study of the two most important short-lived bromocarbons, bromoform (CHBr3) and dibromomethane (CH2Br2), with the Goddard Earth Observing System Chemistry Climate Model (GEOS CCM) to account for this missing stratospheric bromine. We derive a "top-down" emission estimate of CHBr3 and CH2Br2 using airborne measurements in the Pacific and North American troposphere and lower stratosphere obtained during previous NASA aircraft campaigns. Our emission estimate suggests that to reproduce the observed concentrations in the free troposphere, a global oceanic emission of 425 Gg Br yr(exp -1) for CHBr3 and 57 Gg Br yr(exp -l) for CH2Br2 is needed, with 60% of emissions from open ocean and 40% from coastal regions. Although our simple emission scheme assumes no seasonal variations, the model reproduces the observed seasonal variations of the short-lived bromocarbons with high concentrations in winter and low concentrations in summer. This indicates that the seasonality of short-lived bromocarbons is largely due to seasonality in their chemical loss and transport. The inclusion of CHBr3 and CH2Br2 contributes 5 pptv bromine throughout the stratosphere. Both the source gases and inorganic bromine produced from source gas degradation (BrSLS) in the troposphere are transported into the stratosphere, and are equally important. Inorganic bromine accounts for half (2.5 pptv) of the bromine from the inclusion of CHBr3 and CHzBr2 near the tropical tropopause and its contribution rapidly increases to 100% as altitude increases. More than 85% of the wet scavenging of Br(sub y)(sup VSLS) occurs in large-scale precipitation below 500 hPa. Our sensitivity study with wet scavenging in convective updrafts switched off suggests that Br(sub y)(sup SLS) in the stratosphere is not sensitive to convection. Convective scavenging only

  2. Isotope toolbox turns 10

    DEFF Research Database (Denmark)

    Wenander, Fredrik; Riisager, Karsten

    2012-01-01

    REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes.......REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes....

  3. Isotope research materials

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M. K.; Young, Jr, F. W.

    1977-10-01

    Preparation of research isotope materials is described. Topics covered include: separation of tritium from aqueous effluents by bipolar electrolysis; stable isotope targets and research materials; radioisotope targets and research materials; preparation of an 241Am metallurgical specimen; reactor dosimeters; ceramic and cermet development; fission-fragment-generating targets of 235UO2; and wire dosimeters for Westinghouse--Bettis. (GHT)

  4. Molecular characterization of BrMYB28 and BrMYB29 paralogous transcription factors involved in the regulation of aliphatic glucosinolate profiles in Brassica rapa ssp. pekinensis.

    Science.gov (United States)

    Baskar, Venkidasamy; Park, Se Won

    2015-07-01

    Glucosinolates (GSL) are one of the major secondary metabolites of the Brassicaceae family. In the present study, we aim at characterizing the multiple paralogs of aliphatic GSL regulators, such as BrMYB28 and BrMYB29 genes in Brassica rapa ssp. pekinensis, by quantitative real-time PCR (qRT-PCR) analysis in different tissues and at various developmental stages. An overlapping gene expression pattern between the BrMYBs as well as their downstream genes (DSGs) was found at different developmental stages. Among the BrMYB28 and BrMYB29 paralogous genes, the BrMYB28.3 and BrMYB29.1 genes were dominantly expressed in most of the developmental stages, compared to the other paralogs of the BrMYB genes. Furthermore, the differential expression pattern of the BrMYBs was observed under various stress treatments. Interestingly, BrMYB28.2 showed the least expression in most developmental stages, while its expression was remarkably high in different stress conditions. More specifically, the BrMYB28.2, BrMYB28.3, and BrMYB29.1 genes were highly responsive to various abiotic and biotic stresses, further indicating their possible role in stress tolerance. Moreover, the in silico cis motif analysis in the upstream regulatory regions of BrMYBs showed the presence of various putative stress-specific motifs, which further indicated their responsiveness to biotic and abiotic stresses. These observations suggest that the dominantly expressed BrMYBs, both in different developmental stages and under various stress treatments (BrMYB28.3 and BrMYB29.1), may be potential candidate genes for altering the GSL level through genetic modification studies in B. rapa ssp. pekinensis. Copyright © 2015. Published by Elsevier SAS.

  5. Phase Control of BR/SBR Blends by Silica Particles

    Science.gov (United States)

    Inai, Motoyuki; Aizawa, Seiji; Ito, Masayoshi

    A phase control of butadiene rubber (BR)/styrene-butadiene rubber (SBR) blends was examined by using silica particles. The phase structure of the blends was qualitatively evaluated from transmission electron microscope (TEM) observation and temperature dependence of mechanical tanδ. It was found that the temperature dependence of tanδ was dependent on the size of agglomerate formed by silica particles in the blend. The vulcanized blends with small agglomerates showed a single tanδ peak suggesting a pseudo-miscible state. The vulcanized blends with large agglomerates showed two tanδ peaks corresponding to the Tgs of BR and SBR. The mutual dissolution of BR and SBR phases above the UCST line where the vulcanization was carried out might be disturbed by large agglomerates formed by silica particles in the blends.

  6. Isotopic characteristics of canopies in simulated leaf assemblages

    Science.gov (United States)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the ;canopy effect; could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  7. Organic Superconductor k-(BEDT-TTF)2Cu[N(CN)2]Br - A Tunable Electronic System across the Mott Transition -

    Science.gov (United States)

    Tokumoto, M.; Kinoshita, N.; Tanaka, Y.; Kinoshita, T.; Anzai, H.

    1998-03-01

    k-(BEDT-TTF)2Cu[N(CN)2]Br, is an organic superconductor with the highest Tc of 11.6K at ambient pressure (A. M. Kini et al., Inorg. Chem. 29, 2555 (1990)). We have reported a normal isotope effect,when all the hydrogen atoms of BEDT-TTF are replaced with deuterium, in other words, Tc was depressed by as much as 0.9 K (M. Tokumoto et al., J. Phys. Soc. Jpn. 60, 1426 (1991)), in contrast to the "inverse isotope effect" commonly observed in organic superconductors (K. Oshima, et al., Synth. Metals 27, A473 (1988)) . Recently, it was reported that the deuterated k-(BEDT-TTF)2Cu[N(CN)2]Br is of an insulating nature similar to k-(BEDT-TTF)2Cu[N(CN)2]Cl when cooled rapidly(Y. Nakazawa and K. Kanoda, Phys. Rev. B 53, R8875 (1996)). Here we report on the results of reexamination of the superconducting transition of deuterated k-(BEDT-TTF)2Cu[N(CN)2]Br by SQUID measurements with special attention to the cooling speed ranging from 10K/min to less than 0.01K/min. We observed a significant effect not only on the superconducting transition temperature Tc but also on the superconducting volume fraction.

  8. Nuclear Structure of N $\\simeq$ 56 Krypton Isotopes

    CERN Multimedia

    2002-01-01

    In view of the strong overlap in subject matter, the proposals IP-39 and 40 were considered together by the ISOLDE-Committee, and a combined investigation was suggested to be presented to the PSCC.\\\\ \\\\ First results on $\\beta$-decay properties of very neutron-rich Br isotopes (Z=35) indicate a rather smooth onset of deformation already below N=60 and the existence of a deformed N=56 subshell gap. This behaviour is in contrast to earlier observations of a sudden onset of strong deformations at N=60 for $ \\% Z ge $ 37 nuclei. \\\\ \\\\ We propose to study at CERN-ISOLDE nuclear structure properties of N=55 - 57 Kr isotopes from $\\beta$-decay of $^9

  9. Stratospheric BrONO2 observed by MIPAS

    Directory of Open Access Journals (Sweden)

    H. Fischer

    2009-03-01

    Full Text Available The first measurements of stratospheric bromine nitrate (BrONO2 are reported. Bromine nitrate has been clearly identified in atmospheric infrared emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS aboard the European Envisat satellite, and stratospheric concentration profiles have been determined for different conditions (day and night, different latitudes. The BrONO2 concentrations show strong day/night variations, with much lower concentrations during the day. Maximum volume mixing ratios observed during night are 20 to 25 pptv. The observed concentration profiles are in agreement with estimations from photochemical models and show that the current understanding of stratospheric bromine chemistry is generally correct.

  10. Skandaalin vaikutus brändin imagoon - Case Audi

    OpenAIRE

    Puntalo, Ville-Veikko

    2016-01-01

    Opinnäytetyössä tutkittiin Volkswagenin päästöhuijausskandaalin vaikutusta Audi-brändin imagoon. Tutkimuksessa pyrittiin selvittämään onko ennakoitavissa mahdollisia myyntitulosten muutoksia ja johtuivatko ne kyseisestä skandaalista. Opinnäytetyön teoriaosuudessa perehdyttiin ostokäyttäytymisen prosessiin, brändin rakentumiseen, positiivisen maineen saavuttamiseen ja tunnettuihin yritysmaailman skandaaleihin. Lisäksi käytiin läpi Volkswagen päästöskandaalin taustaa sekä sen seurauksia. ...

  11. Atmospheric test of the J(BrONO2/kBrO+NO2 ratio: implications for total stratospheric Bry and bromine-mediated ozone loss

    Directory of Open Access Journals (Sweden)

    S. Kreycy

    2013-07-01

    Full Text Available We report on time-dependent O3, NO2 and BrO profiles measured by limb observations of scattered skylight in the stratosphere over Kiruna (67.9° N, 22.1° E on 7 and 8 September 2009 during the autumn circulation turn-over. The observations are complemented by simultaneous direct solar occultation measurements around sunset and sunrise performed aboard the same stratospheric balloon payload. Supporting radiative transfer and photochemical modelling indicate that the measurements can be used to constrain the ratio J(BrONO2/kBrO+NO2, for which at T = 220 ± 5 K an overall 1.7 (+0.4 −0.2 larger ratio is found than recommended by the most recent Jet Propulsion Laboratory (JPL compilation (Sander et al., 2011. Sensitivity studies reveal the major reasons are likely to be (1 a larger BrONO2 absorption cross-section σBrONO2, primarily for wavelengths larger than 300 nm, and (2 a smaller kBrO+NO2 at 220 K than given by Sander et al. (2011. Other factors, e.g. the actinic flux and quantum yield for the dissociation of BrONO2, can be ruled out. The observations also have consequences for total inorganic stratospheric bromine (Bry estimated from stratospheric BrO measurements at high NOx loadings, since the ratio J(BrONO2/kBrO+NO2 largely determines the stratospheric BrO/Bry ratio during daylight. Using the revised J(BrONO2/kBrO+NO2 ratio, total stratospheric Bry is likely to be 1.4 ppt smaller than previously estimated from BrO profile measurements at high NOx loadings. This would bring estimates of Bry inferred from organic source gas measurements (e.g. CH3Br, the halons, CH2Br2, CHBr3, etc. into closer agreement with estimates based on BrO observations (inorganic method. The consequences for stratospheric ozone due to the revised J(BrONO2/kBrO+NO2 ratio are small (maximum −0.8%, since at high NOx (for which most Bry assessments are made the enhanced ozone loss by overestimating Bry is compensated for by the suppressed ozone loss due to the

  12. 75 FR 51693 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Models BR700-710A1-10; BR700-710A2...

    Science.gov (United States)

    2010-08-23

    ... Directives; Rolls-Royce Deutschland Ltd & Co KG Models BR700-710A1-10; BR700-710A2-20; and BR700-710C4-11...-2251. Contact Rolls-Royce Deutschland Ltd & Co KG, Eschenweg 11, Dahlewitz, 15827 Blankenfelde-Mahlow..., notified us that an unsafe condition may exist on Rolls-Royce Deutschland Ltd & Co KG Models BR700-710A1-10...

  13. Transportation of medical isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, D.L.

    1997-11-19

    A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document.

  14. Product analysis and kinetics of Br-initiated gas-phase oxidation of dimethyl sulphide; Produktanalyse und Kinetik der Br-initiierten Gasphasenoxidation von Dimethylsulfid

    Energy Technology Data Exchange (ETDEWEB)

    Becker, K.H.; Maurer, T.

    1996-07-01

    High Br concentrations in maritime environments may render the reaction between Br radicals and dimethyl sulphide an important process. According to the literature this system has as yet not been studied with a mind to clarifying the reaction mechanisms and performing a product analysis. Thus, for example, the decomposition of the DMS-Br adduct remains to be clarified. The purpose of the present study was therefore to examine the reaction between dimethyl sulphide and Br radicals and so gain information on the decomposition mechanism. This implied a determination of the velocity constant and a product analysis of the reaction between Br radicals and dimethyl sulphide. In addition the velocity constant of the reaction between Br radicals and dimethylsulphoxide (a consequent product of DMS oxidation) was to be determined. (orig.) [Deutsch] Hohe Br-Konzentrationen in maritimen Gebieten machen die Reaktion von Br-Radikalen mit Dimethylsulfid moeglicherweise zu einem wichtigen Prozess. In der Literatur fehlen eingehende Untersuchungen dieses Systems hinsichtlich der Aufklaerung der Reaktionsmechanismen und der Produktanalyse. So ist zum Beispiel der Zerfall des DMS-Br-Adduktes nicht aufgeklaert. Aus diesen Gruenden soll im Rahmen dieser Arbeit die Reaktion von Dimethylsulfid mit Br-Radikalen untersucht werden, um Informationen ueber den Abbaumechanismus zu erhalten. Darunter fallen die Bestimmung der Geschwindigkeitskonstanten und die Produktanalyse der Reaktion von Br-Radikalen mit Dimethylsulfid. Zusaetzlich soll die Geschwindigkeitskonstante der Reaktion vom Br-Radikalen mit Dimethylsulfoxid (einem Folgeprodukt der DMS-Oxidation) bestimmt werden. (orig.)

  15. Isotope and density profile effects on pedestal neoclassical transport

    Science.gov (United States)

    Buller, S.; Pusztai, I.

    2017-10-01

    Cross-field neoclassical transport of heat, particles and momentum is studied in sharp density pedestals, with a focus on isotope and profile effects, using a radially global approach. Global effects—which tend to reduce the peak ion heat flux, and shift it outward—increase with isotope mass for fixed profiles. The heat flux reduction exhibits a saturation with a favorable isotopic trend. A significant part of the heat flux can be convective even in pure plasmas, unlike in the plasma core, and it is sensitive to how momentum sources are distributed between the various species. In particular, if only ion momentum sources are allowed, in global simulations of pure plasmas the ion particle flux remains close to its local value, while this may not be the case for simulations with isotope mixtures or electron momentum sources. The radial angular momentum transport that is a finite orbit width effect, is found to be strongly correlated with heat sources.

  16. Redetermination of the Crystal Structure of Al2Br6

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Poulsen, Finn W.; Nielsen, Kurt

    1997-01-01

    . In accordance with previous results, the structure belongs to the monoclinic space group P2(1)/a, no. 14, C-2h(5), with a = 10.301(4), b = 7.095(2), c = 7.525(3) Angstrom, and beta = 96.44(3)degrees, and with two Al2Br6 molecules per unit cell. The single crystal was refined to R = 0.0746. Rather similar......The structure of aluminium bromide has been reinvestigated by X-ray diffraction in three different ways: (a) on a single crystal grown in a glass capillary, (b) on powder in a Debye-Scherrer glass capillary and (c) on an area of powder placed in a protective container for Bragg-Brentano geometry...... structural results were obtained from full-profile Rietveld refinements of powder data [goodness of fit = 1.38 and 2.54 for (b) and (c), respectively]. The Al2Br6 molecule consists of two edge-sharing, almost regular AlBr4 tetrahedra. The Al-Br bond distances are in the range 2.21-2.42 Angstrom...

  17. Fragment production in 16 O· 80 Br reaction within dynamical ...

    Indian Academy of Sciences (India)

    ... Public Lectures · Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Pramana – Journal of Physics; Volume 59; Issue 1. Fragment production in 16O + 80Br reaction within dynamical microscopic theory. Rajeev K Puri Jaivir Singh Suneel Kumar. Research Articles Volume 59 Issue 1 July 2002 pp 19-31 ...

  18. (KNa)Br phosphor for ionizing radiation dosimetry

    Indian Academy of Sciences (India)

    Lyoluminescence; γ-ray dose; radiation dosimetry; phosphor; (KNa)Br. 1. Introduction. The measurement of radiation dose has become a science of ever increasing importance due to the estimation of risk and benefits inherent to the uses and to the exposure of ionizing radiation. When strongly energized, crystals are ...

  19. Overexpression of BrSAC1 encoding a phosphoinositide ...

    African Journals Online (AJOL)

    The full length gene (BrSAC1; GenBank accession no., GU434275) contained 1999 base pairs (bp), with an open reading frame of 1785 bp, encoding a polypeptide of 594 amino acids with a predicted molecular weight of 65 kDa, including a putative N-terminal signal peptide (the signal peptide counted within the 594 ...

  20. Monika Elisabeth Bründl, Lexikalische Dynamik – Kognitiv ...

    African Journals Online (AJOL)

    Information Technology

    Key concepts are the mental lexicon, metaphor and metonymy as central processes in the creation of new lexical units (as defined by Cruse 1986: 77), and iconicity as the cognitive answer to the structural tenet of the arbitrariness of the linguistic sign. Bründl argues that the cognitive approach so far has been mainly applied.

  1. Narva kant vajab oma brändi / Esko Passila

    Index Scriptorium Estoniae

    Passila, Esko

    2007-01-01

    Autor leiab, et Ida-Virumaa peaks looma ühtse tugeva brändi, mille alusel tulevikuotsuseid teha. See peaks tooma välja soodsa asukoha eelised, võimalused, tööjõu kättesaadavuse, kasutusvalmid maa-alad, hinnad jne.

  2. Overexpression of BrSAC1 encoding a phosphoinositide ...

    African Journals Online (AJOL)

    2013-04-10

    Apr 10, 2013 ... Key words: Abiotic stress, Brassica rapa, phosphoinositide phosphatase, transgenic plant. INTRODUCTION. Plant growth is strongly ... specific primers for the analysis of BrSAC1 expression in germinating seeds were: ..... Ministry for Food, Agriculture, Forestry and Fisheries,. Republic of Korea and 2012 ...

  3. Crystal structures of MBi{sub 2}Br{sub 7} (M = Rb, Cs) - filled variants of AX{sub 7} sphere packing

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jen-Hui; Wolff, Alexander [Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, 01062 Dresden (Germany); Ruck, Michael [Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, 01062 Dresden (Germany); Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Str. 40, 01187 Dresden (Germany)

    2016-03-15

    The reinvestigation of the pseudo-binary systems MBr-BiBr{sub 3} (M = Rb, Cs) revealed two new phases with composition MBi{sub 2}Br{sub 7}. Both compounds are hygroscopic and show brilliant yellow color. The crystal structures were solved from X-ray single crystal diffraction data. The isostructural compounds adopt a new structure type in the triclinic space group P anti 1. The lattice parameters are a = 755.68(3) pm, b = 952.56(3) pm, c = 1044.00(4) pm, α = 76.400(2) , β = 84.590(2) , γ = 76.652(2) for RbBi{sub 2}Br{sub 7} and a = 758.71(5) pm, b = 958.23(7) pm, c = 1060.24(7) pm, α = 76.194(3) , β = 83.844(4) , γ = 76.338(3) for CsBi{sub 2}Br{sub 7}. The crystal structures consist of M{sup +} cations in anticuboctahedral coordination by bromide ions and bromidobismuthate(III) layers {sup 2}{sub ∞}[Bi{sub 2}Br{sub 7}]{sup -}. The 2D layers comprise pairs of BiBr{sub 6} octahedra sharing a common edge. The Bi{sub 2}Br{sub 10} double octahedra are further connected by common vertices. The bismuth(III) atoms increase their mutual distance in the double octahedra by off-centering so that the BiBr{sub 6} octahedra are distorted. The CsBi{sub 2}Br{sub 7} type can be interpreted as a common hexagonal close sphere packing of M and Br atoms, in which 1/4 of the octahedral voids are filled by Bi atoms. The structure type was systematically analyzed and compared with alternative types of common packings. The existence of a compound with the suggested composition CsBiBr{sub 4} could not be verified experimentally. (Copyright copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Isotopes in Condensed Matter

    CERN Document Server

    G Plekhanov, Vladimir

    2013-01-01

    This book provides a concise introduction to the newly created sub-discipline of solid state physics isotopetronics. The role of isotopes in materials and their properties are describe  in this book. The problem of the enigma of the atomic mass in microphysics is briefly discussed.  The range of the applications of isotopes is wide: from biochemical process in living organisms to modern technical applications in quantum information. Isotopetronics promises to improve nanoelectronic and optoelectronic devices. With numerous illustrations this book is useful to researchers, engineers and graduate students.

  5. Oxygen Isotope Systematics of Almahata Sitta

    Science.gov (United States)

    Kita, N. T.; Goodrich, C. A.; Herrin, J. S.; Shaddad, M. H.; Jenniskens, P.

    2011-01-01

    The Almahata Sitta (hereafter "AHS") meteorite was derived from an impact of asteroid 2008TC3 on Earth and is classified as an anomalous polymict ureilite. More than 600 meteorite fragments have been recovered from the strewnfield. Previous reports indicate that these fragments consist mainly of ureilitic materials with textures and compositions, while some fragments are found to be chondrites of a wide range of chemical classes. Bulk oxygen three isotope analyses of ureilitic fragments from AHS fall close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line similar to ureilites. In order to further compare AHS with known ureilites, we performed high precision SIMS (Secondary Ion Mass Spectrometer) oxygen isotope analyses of some AHS samples

  6. Simulated oxygen isotopes in cave drip water and speleothem calcite in European caves

    Directory of Open Access Journals (Sweden)

    A. Wackerbarth

    2012-11-01

    Full Text Available Interpreting stable oxygen isotope18O records from stalagmites is still one of the complex tasks in speleothem research. Here, we present a novel model-based approach, where we force a model describing the processes and modifications of δ18O from rain water to speleothem calcite (Oxygen isotope Drip water and Stalagmite Model – ODSM with the results of a state-of-the-art atmospheric general circulation model enhanced by explicit isotope diagnostics (ECHAM5-wiso. The approach is neither climate nor cave-specific and allows an integrated assessment of the influence of different varying climate variables, e.g. temperature and precipitation amount, on the isotopic composition of drip water and speleothem calcite. <br>> First, we apply and evaluate this new approach under present-day climate conditions using observational data from seven caves from different geographical regions in Europe. Each of these caves provides measured δ18O values of drip water and speleothem calcite to which we compare our simulated isotope values. For six of the seven caves modeled δ18O values of drip water and speleothem calcite are in good agreement with observed values. The mismatch of the remaining caves might be caused by the complexity of the cave system, beyond the parameterizations included in our cave model. <br>> We then examine the response of the cave system to mid-Holocene (6000 yr before present, 6 ka climate conditions by forcing the ODSM with ECHAM5-wiso results from 6 ka simulations. For a set of twelve European caves, we compare the modeled mid-Holocene-to-modern difference in speleothem calcite δ18O to available measurements. We show that the general European changes are simulated well. However, local discrepancies are found, and might be explained either by a too low model resolution, complex local soil-atmosphere interactions affecting evapotranspiration or by cave specific factors

  7. The origin of the conductivity maximum in molten salts. II. SnCl2 and HgBr2

    Science.gov (United States)

    Aravindakshan, Nikhil P.; Kuntz, Colin M.; Gemmell, Kyle E.; Johnson, Keith E.; East, Allan L. L.

    2016-09-01

    The phenomenon of electrical conductivity maxima of molten salts versus temperature during orthobaric (closed-vessel) conditions is further examined via ab initio simulations. Previously, in a study of molten BiCl3, a new theory was offered in which the conductivity falloff at high temperatures is due not to traditional ion association, but to a rise in the activation energy for atomic ions hopping from counterion to counterion. Here this theory is further tested on two more inorganic melts which exhibit conductivity maxima: another high-conducting melt (SnCl2, σmax = 2.81 Ω-1 cm-1) and a low-conducting one (HgBr2, σmax = 4.06 × 10-4 Ω-1 cm-1). First, ab initio molecular dynamics simulations were performed and again appear successful in reproducing the maxima for both these liquids. Second, analysis of the simulated liquid structure (radial distributions, species concentrations) was performed. In the HgBr2 case, a very molecular liquid like water, a clear Grotthuss chain of bromide transfers was observed in simulation when seeding the system with a HgBr+ cation and HgBr3- anion. The first conclusion is that the hopping mechanism offered for molten BiCl3 is simply the Grotthuss mechanism for conduction, applicable not just to H+ ions, but also to halide ions in post-transition-metal halide melts. Second, it is conjectured that the conductivity maximum is due to rising activation energy in network-covalent (halide-bridging) melts (BiCl3, SnCl2, PbCl2), but possibly a falling Arrhenius prefactor (collision frequency) for molecular melts (HgBr2).

  8. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    About 3000 different isotopes have been discovered until now. A recent compilation sum- marized details of the discovery of all isotopes [1–4] including the year, laboratory and country of discovery as well as the production mechanism used to produce the isotopes. Fission, one of the largest contributing production ...

  9. Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    S. Moukhtar

    2011-11-01

    Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl−1, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry. <br>> The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m−3 and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m−3. <br>> In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m−3 range in rural areas to more than 200 pg m−3 in some samples from a suburban location.

  10. Steering dissociation of Br2 molecules with two femtosecond pulses via wave packet interference.

    Science.gov (United States)

    Han, Yong-Chang; Yuan, Kai-Jun; Hu, Wen-Hui; Yan, Tian-Min; Cong, Shu-Lin

    2008-04-07

    The dissociation dynamics of Br2 molecules induced by two femtosecond pump pulses are studied based on the calculation of time-dependent quantum wave packet. Perpendicular transition from X 1Sigma g+ to A 3Pi 1u+ and 1Pi 1u+ and parallel transition from X 1Sigma g+ to B 3Pi 0u+, involving two product channels Br (2P3/2)+Br (2P3/2) and Br (2P3/2)+Br* (2P1/2), respectively, are taken into account. Two pump pulses create dissociating wave packets interfering with each other. By varying laser parameters, the interference of dissociating wave packets can be controlled, and the dissociation probabilities of Br2 molecules on the three excited states can be changed to different degrees. The branching ratio of Br*/(Br+Br*) is calculated as a function of pulse delay time and phase difference.

  11. Close-ups

    DEFF Research Database (Denmark)

    Fausing, Bent

    2013-01-01

    Investigations in the close-up and its meaning regarding nearness, abstraction and transparency. Face, facelike and animism are also major key-words in thsi article... . I have always been fascinated with the close-up, not as an end, but a filter of opportunities to open up for and nearness...... of transcendence, associations and memories. The close-up is not the end, it rather in my view to be regarded as a beginning of different perceptions...

  12. Cluster emission in superdeformed Sr isotopes in the ground state ...

    Indian Academy of Sciences (India)

    2017-01-03

    Jan 3, 2017 ... Abstract. Cluster decay of superdeformed 76,78,80Sr isotopes in their ground state are studied taking the Coulomb and proximity potential as the interacting barrier for the post-scission region. The predicted T1/2 values are found to be in close agreement with those values reported by the preformed cluster ...

  13. elemental and isotopic compositions of organic carbon and nitrogen ...

    African Journals Online (AJOL)

    ABSTRACT. A 29 cm long core recovered from a water depth of 5 m in a small closed lake located in the. Empakai crater northern Tanzania, is used to document the contents of organic carbon and nitrogen, stable isotopes composition of organic carbon and nitrogen, and C/N ratios and to infer climatic changes from these ...

  14. Isotope effect on the zero point energy shift upon condensation

    Energy Technology Data Exchange (ETDEWEB)

    Kornblum, Z.C.; Ishida, T.

    1977-07-01

    The various isotope-dependent and independent atomic and molecular properties that pertain to the isotopic difference between the zero point energy (ZPE) shifts upon condensation were derived. The theoretical development of the change of the ZPE associated with the internal molecular vibrations, due to the condensation of the gaseous molecules, is presented on the basis of Wolfsberg's second-order perturbation treatment of the isotope-dependent London dispersion forces between liquid molecules. The isotope effect on the ZPE shift is related to the difference between the sums of the integrated intensities of the infrared absorption bands of the two gaseous isotopic molecules. The effective atomic charges are also calculated from available experimental infrared intensity data. The effects of isotopic substitutions of carbon-13 for carbon-12 and/or deuterium for protium, in ethylene, methane, and the fluorinated methanes, CH/sub 3/F, CH/sub 2/F/sub 2/, CHF/sub 3/, and CF/sub 4/, on the ZPE shift upon condensation are calculated. These results compare well with the Bigeleisen B-factors, which are experimentally obtained from vapor pressure measurements of the isotopic species. Each of the following molecular properties will tend to increase the isotopic difference between the ZPE shifts upon condensation: (1) large number of highly polar bonds, (2) high molecular weight, (3) non-polar (preferably) or massive molecule, (4) non-hydrogenous molecule, and (5) closely packed liquid molecules. These properties will result in stronger dispersion forces in the liquid phase between the lighter molecules than between the isotopically heavier molecules. 36 tables, 9 figures.

  15. Close Air Support versus Close Combat Attack

    Science.gov (United States)

    2012-12-06

    with parallel Air Force and Army structures and incorporating tactical air control parties ( TACP ) down to the battalion level. This system greatly...Operations Center (ASOC) and the Tactical Air Control Party ( TACP ). Each of these agencies works in concert to facilitate close air support platforms...needed to maintain combat readiness.93 At the corps level and below is a Tactical Air Control Party ( TACP ) organized under the Army Fires Cell (FC

  16. Perceptions of breath alcohol concentration (BrAC) levels among a sample of bar patrons with BrAC values of 0.08% or higher.

    Science.gov (United States)

    Martin, Ryan J; Chaney, Beth H; Cremeens-Matthews, Jennifer; Vail-Smith, Karen

    2016-09-01

    Breath alcohol concentration (BrAC) is a commonly used measure of alcohol intoxication. Because of the potential negative consequences of excessive alcohol consumption, it is important to examine how accurately intoxicated individuals can estimate their BrAC values, especially individuals over the legal BrAC driving threshold (i.e., 0.08%). To better understand perceptions of BrAC values among intoxicated individuals, this field study examined actual BrAC values and BrAC range estimates (0.08% and above, 0.02-0.07%, less than 0.02%) among a sample of bar patrons (N = 454) with BrAC levels at 0.08% or higher. Bivariate and multivariate analyses were conducted to examine the relationship between actual BrAC values and perceived BrAC levels. We also examined whether the following demographic and drinking variables were associated with underestimating BrAC in this sample: gender, age, race, college student status, plans to get home, and hazardous drinking. Results indicated that the majority (60.4%) of participants underestimated their BrAC (i.e., less than 0.08%) and lower BrAC values correlated with underestimating BrAC ranges (p < .001, 95% CI[0.2, 0.6]). Further, females (p = .001, 95% CI[1.3, 3.3]) and participants under 21 (p = .039, 95% CI = 1.0, 2.6) were significantly more likely to estimate their BrAC to be less than 0.08%, which is concerning given that young (less than 21) intoxicated females are a group at high risk for sexual assault on college campuses. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  17. Obtaining continuous BrAC/BAC estimates in the field: A hybrid system integrating transdermal alcohol biosensor, Intellidrink smartphone app, and BrAC Estimator software tools.

    Science.gov (United States)

    Luczak, Susan E; Hawkins, Ashley L; Dai, Zheng; Wichmann, Raphael; Wang, Chunming; Rosen, I Gary

    2017-12-02

    Biosensors have been developed to measure transdermal alcohol concentration (TAC), but converting TAC into interpretable indices of blood/breath alcohol concentration (BAC/BrAC) is difficult because of variations that occur in TAC across individuals, drinking episodes, and devices. We have developed mathematical models and the BrAC Estimator software for calibrating and inverting TAC into quantifiable BrAC estimates (eBrAC). The calibration protocol to determine the individualized parameters for a specific individual wearing a specific device requires a drinking session in which BrAC and TAC measurements are obtained simultaneously. This calibration protocol was originally conducted in the laboratory with breath analyzers used to produce the BrAC data. Here we develop and test an alternative calibration protocol using drinking diary data collected in the field with the smartphone app Intellidrink to produce the BrAC calibration data. We compared BrAC Estimator software results for 11 drinking episodes collected by an expert user when using Intellidrink versus breath analyzer measurements as BrAC calibration data. Inversion phase results indicated the Intellidrink calibration protocol produced similar eBrAC curves and captured peak eBrAC to within 0.0003%, time of peak eBrAC to within 18min, and area under the eBrAC curve to within 0.025% alcohol-hours as the breath analyzer calibration protocol. This study provides evidence that drinking diary data can be used in place of breath analyzer data in the BrAC Estimator software calibration procedure, which can reduce participant and researcher burden and expand the potential software user pool beyond researchers studying participants who can drink in the laboratory. Copyright © 2017. Published by Elsevier Ltd.

  18. NMR Spectroscopic Characterization of Charge Assisted Strong Hydrogen Bonds in Brønsted Acid Catalysis

    Science.gov (United States)

    2016-01-01

    Hydrogen bonding plays a crucial role in Brønsted acid catalysis. However, the hydrogen bond properties responsible for the activation of the substrate are still under debate. Here, we report an in depth study of the properties and geometries of the hydrogen bonds in (R)-TRIP imine complexes (TRIP: 3,3′-Bis(2,4,6-triisopropylphenyl)-1,1′-binaphthyl-2,2′-diylhydrogen phosphate). From NMR spectroscopic investigations 1H and 15N chemical shifts, a Steiner–Limbach correlation, a deuterium isotope effect as well as quantitative values of 1JNH,2hJPH and 3hJPN were used to determine atomic distances (rOH, rNH, rNO) and geometry information. Calculations at SCS-MP2/CBS//TPSS-D3/def2-SVP-level of theory provided potential surfaces, atomic distances and angles. In addition, scalar coupling constants were computed at TPSS-D3/IGLO-III. The combined experimental and theoretical data reveal mainly ion pair complexes providing strong hydrogen bonds with an asymmetric single well potential. The geometries of the hydrogen bonds are not affected by varying the steric or electronic properties of the aromatic imines. Hence, the strong hydrogen bond reduces the degree of freedom of the substrate and acts as a structural anchor in the (R)-TRIP imine complex. PMID:27936674

  19. Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    Directory of Open Access Journals (Sweden)

    J. Kaiser

    2011-07-01

    Full Text Available Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production. <br>> In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state. <br>> I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to

  20. Restaurants closed over Christmas

    CERN Multimedia

    2011-01-01

    The restaurants will be closed during the Christmas holiday period : please note that all three CERN Restaurants will be closed from 5 p.m. on Wednesday, 21 December until Wednesday, 4 January inclusive. The Restaurants will reopen on Thursday, 5 January 2012.

  1. Heavy nickel isotope compositions in rivers and the oceans

    Science.gov (United States)

    Cameron, V.; Vance, D.

    2014-03-01

    Nickel is a biologically-active trace metal whose dissolved concentration depth profiles in the ocean show nutrient-like behaviour. If the pronounced removal of nickel from the dissolved phase in the surface ocean, and its return in the deep, is associated with an isotopic fractionation nickel isotopes may be able to yield constraints on the precise biogeochemical processes involved. Here we present the first nickel isotope data for seawater along with data for the dissolved phase of rivers, one of the principal sources of nickel to the oceans. The dissolved phase of rivers exhibits substantial variability in both Ni concentration and δ60Ni: from 2.2 to 35 nmol kg-1 and +0.29 to +1.34‰, respectively. The most striking result from the nickel isotope analyses of rivers is that they are substantially heavier (by up to 1‰ for δ60Ni) than the range for silicate rocks on the continents, a finding that is analogous to that for other transition metal isotope systems. If the data presented here are close to representative of the global riverine flux, they suggest an annual input of Ni to the oceans of 3.6 × 108moles, and a discharge- and concentration-weighted δ60Ni average of +0.80‰. The relationship between Ni isotopes and concentrations shows similarities with those for other transition metal isotope systems, where the main control has been suggested to be isotopic partitioning between the dissolved phase and particulates, either in the weathering environment or during transport. In stark contrast to the rivers, the dataset for seawater is very homogeneous, with 2SD of the entire dataset being only twice the analytical reproducibility. The second main feature is that seawater is distinctly heavier in Ni isotopes than rivers. The average δ60Ni is 1.44 ± 0.15‰ (2SD), and only 2 of the 29 seawater analyses have a Ni isotopic composition that is lighter than the heaviest river. The lack of an isotopic shift associated with the drawdown of nickel concentrations

  2. Identification of Yellow Pigmentation Genes in Brassica rapa ssp. pekinensis Using Br300 Microarray

    Directory of Open Access Journals (Sweden)

    Hee-Jeong Jung

    2014-01-01

    Full Text Available The yellow color of inner leaves in Chinese cabbage depends on its lutein and carotene content. To identify responsible genes for yellow pigmentation in leaves, the transcriptome profiles of white (Kenshin and yellow leaves (Wheessen were examined using the Br300K oligomeric chip in Chinese cabbage. In yellow leaves, genes involved in carotene synthesis (BrPSY, BrPDS, BrCRTISO, and BrLCYE, lutein, and zeaxanthin synthesis (BrCYP97A3 and BrHYDB were upregulated, while those associated with carotene degradation (BrNCED3, BrNCED4, and BrNCED6 were downregulated. These expression patterns might support that the content of both lutein and total carotenoid was much higher in the yellow leaves than that in the white leaves. These results indicate that the yellow leaves accumulate high levels of both lutein and β-carotene due to stimulation of synthesis and that the degradation rate is inhibited. A large number of responsible genes as novel genes were specifically expressed in yellow inner leaves, suggesting the possible involvement in pigment synthesis. Finally, we identified three transcription factors (BrA20/AN1-like, BrBIM1, and BrZFP8 that are specifically expressed and confirmed their relatedness in carotenoid synthesis from Arabidopsis plants.

  3. High gradient rf gun studies of CsBr photocathodes

    Directory of Open Access Journals (Sweden)

    Theodore Vecchione

    2015-04-01

    Full Text Available CsBr photocathodes have 10 times higher quantum efficiency with only 3 times larger intrinsic transverse emittance than copper. They are robust and can withstand 80  MV/m fields without breaking down or emitting dark current. They can operate in 2×10^{−9}  torr vacuum and survive exposure to air. They are well suited for generating high pulse charge in rf guns without a photocathode transfer system.

  4. Four-dimensional quantum study on exothermic complex-forming reactions: Cl- + CH3Br-->ClCH3+Br-.

    Science.gov (United States)

    Hennig, Carsten; Schmatz, Stefan

    2005-06-15

    The exothermic gas-phase bimolecular nucleophilic substitution (S(N)2) reaction Cl(-)+CH(3)Br (upsilon1',upsilon2',upsilon3')-->ClCH(3) (upsilon1,upsilon2,upsilon3)+Br- and the corresponding endothermic reverse reaction have been studied by time-independent quantum scattering calculations in hyperspherical coordinates on a coupled-cluster potential-energy surface. The dimensionality-reduced model takes four degrees of freedom into account [Cl-C and C-Br stretching modes (quantum numbers upsilon3' and upsilon3); totally symmetric modes of the methyl group, i.e., C-H stretching (upsilon1' and upsilon1) and umbrella bending vibrations (upsilon2' and upsilon2)]. Diagonalization of the Hamiltonian was performed employing the Lanczos algorithm with a variation of partial reorthogonalization. A narrow grid in the total energy was employed so that long-living resonance states could be resolved and extracted. While excitation of the reactant umbrella bending mode already leads to a considerable enhancement of the reaction probability, its combination with vibrational excitation of the broken C-Br bond, (0, 1, 1), results in a strong synergic effect that can be rationalized by the similarity with the classical transitional normal mode. Exciting the C-H stretch has a non-negligible effect on the reaction probability, while for larger translational energies this mode follows the expected spectatorlike behavior. Combination of C-Br stretch and symmetric C-H, (1,0,1), stretch does not show a cooperative effect. Contrary to the spectator mode concept, energy originally stored in the C-H stretching mode is by no means conserved, but almost completely released in other modes of the reaction products. Products are most likely formed in states with a high degree of excitation in the new C-Cl bond, while the internal modes of the methyl group are less important. Reactants with combined umbrella/C-Br stretch excitation, (0, 1, 1), may yield products with two quanta in the umbrella mode.

  5. Iron isotope systematics in planetary reservoirs

    Science.gov (United States)

    Sossi, Paolo A.; Nebel, Oliver; Foden, John

    2016-10-01

    = 0.10 ± 0.01 ‰ (2SE) after correction to primary magmas, and can be produced from single stage melt extraction. Conversely, iron isotopes in arc basalts are more varied (- 0.2 <δ57 Fe (‰) < + 0.2) than can be produced from partial melting. Their iron isotope compositions are significantly lighter, suggesting they form from mantle re-enriched in light Fe and/or more depleted than Depleted MORB Mantle (DMM). If arc sources are more oxidised, an agent other than iron is required. Magmatic differentiation drives enrichment in heavy isotopes by partial melting of crustal rocks, fluid exsolution and crystallisation. Iron isotope trajectories in evolving magmas depend on their initial fO2 and whether the system is closed or open to oxygen and/or mass exchange. Granite end-members carry signatures diagnostic of their tectonic setting, where reduced, anorogenic A-type granites (δ57 Fe = + 0.4 ‰) are heavier than more oxidised I-types (δ57 Fe = + 0.2 ‰).

  6. Optimized Control Rods of the BR2 Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kalcheva, Silva; Koonen, E.

    2007-09-15

    At the present time the BR-2 reactor uses control elements with cadmium as neutron absorbing part. The lower section of the control element is a beryllium assembly cooled by light water. Due to the burn up of the lower end of the cadmium section during the reactor operation, the presently used rods for reactivity control of the BR-2 reactor have to be replaced by new ones. Considered are various types Control Rods with full active part of the following materials: cadmium (Cd), hafnium (Hf), europium oxide (Eu2O3) and gadolinium (Gd2O3). Options to decrease the burn up of the control rod material in the hot spot, such as use of stainless steel in the lower active part of the Control Rod are discussed. Comparison with the characteristics of the presently used Control Rods types is performed. The changing of the characteristics of different types Control Rods and the perturbation effects on the reactor neutronics during the BR-2 fuel cycle are investigated. The burn up of the Control Rod absorbing material, total and differential control rods worth, macroscopic and effective microscopic absorption cross sections, fuel and reactivity evolution are evaluated during approximately 30 operating cycles.

  7. Bréal, un antinaturalisme d’inspiration humboldtienne

    Directory of Open Access Journals (Sweden)

    Babu Jean-Philippe

    2014-07-01

    Full Text Available Dans De la forme et de la fonction des mots, Bréal formulait, dès 1866, outre une critique générale du formalisme de la philologie comparative depuis Bopp, une thèse radicalement opposée à l’orientation naturaliste de l’évolutionnisme linguistique de Schleicher. Cette thèse, que nous prendrons le risque de définir comme thèse du primat de la fonction sur la forme linguistique, est au coeur de ce programme de linguistique générale pour lequel Bréal allait forger, quelques années plus tard, le mot de sémantique. Fortement marqué par la notion humboldtienne d’innere Sprachform, Bréal, contrairement à Saussure, n'abandonnera jamais le changement linguistique au hasard de l'histoire et maintiendra l'intelligence comme premier moteur des langues, quitte à poser la nécessité de repenser cette intelligence.

  8. A coherent mathematical characterization of isotope trace extraction, isotopic envelope extraction, and LC-MS correspondence

    Science.gov (United States)

    2015-01-01

    Background Liquid chromatography-mass spectrometry is a popular technique for high-throughput protein, lipid, and metabolite comparative analysis. Such statistical comparison of millions of data points requires the generation of an inter-run correspondence. Though many techniques for generating this correspondence exist, few if any, address certain well-known run-to-run LC-MS behaviors such as elution order swaps, unbounded retention time swaps, missing data, and significant differences in abundance. Moreover, not all extant correspondence methods leverage the rich discriminating information offered by isotope envelope extraction informed by isotope trace extraction. To date, no attempt has been made to create a formal generalization of extant algorithms for these problems. Results By enumerating extant objective functions for these problems, we elucidate discrepancies between known LC-MS data behavior and extant approaches. We propose novel objective functions that more closely model known LC-MS behavior. Conclusions Through instantiating the proposed objective functions in the form of novel algorithms, practitioners can more accurately capture the known behavior of isotope traces, isotopic envelopes, and replicate LC-MS data, ultimately providing for improved quantitative accuracy. PMID:25951936

  9. Stable isotopic variation in tropical forest plants for applications in primatology.

    Science.gov (United States)

    Blumenthal, Scott A; Rothman, Jessica M; Chritz, Kendra L; Cerling, Thure E

    2016-10-01

    Stable isotope analysis is a promising tool for investigating primate ecology although nuanced ecological applications remain challenging, in part due to the complex nature of isotopic variability in plant-animal systems. The aim of this study is to investigate sources of carbon and nitrogen isotopic variation at the base of primate food webs that reflect aspects of primate ecology. The majority of primates inhabit tropical forest ecosystems, which are dominated by C3 vegetation. We used stable isotope ratios in plants from Kibale National Park, Uganda, a well-studied closed-canopy tropical forest, to investigate sources of isotopic variation among C3 plants related to canopy stratification, leaf age, and plant part. Unpredictably, our results demonstrate that vertical stratification within the canopy does not explain carbon or nitrogen isotopic variation in leaves. Leaf age can be a significant source of isotopic variation, although the direction and magnitude of this difference is not consistent across tree species. Some plant parts are clearly differentiated in carbon and nitrogen isotopic composition, particularly leaves compared to non-photosynthetic parts such as reproductive parts and woody stem parts. Overall, variation in the isotopic composition of floral communities, plant species, and plant parts demonstrates that stable isotope studies must include analysis of local plant species and parts consumed by the primates under study from within the study area. Am. J. Primatol. 78:1041-1054, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  10. Equilibrium nickel isotope fractionation in nickel sulfide minerals

    Science.gov (United States)

    Liu, Shanqi; Li, Yongbing; Ju, Yiwen; Liu, Jie; Liu, Jianming; Shi, Yaolin

    2018-02-01

    Nickel is an important element on Earth, and a major element in the Earth's core, and plays important roles in many geological and biological systems. As an important sink of Ni, Ni sulfides are closely concerned with Ni migration in magma systems and the genesis and evolution of magmatic sulfide deposits. Ni isotopes of Ni sulfides may be a powerful geochemical tracer in magmatic processes and evolution of magmatic sulfide deposits. However Ni isotope fractionation factors of sulfides remain poorly known, which makes the applications of Ni isotopes to geological problems associated with sulfides difficult. In this study, the first-principles methods are used to compute Ni isotope fractionation parameters of polydymite (Ni3S4), heazlewoodite (Ni3S2), millerite (NiS), godlevskite (Ni9S8) and vaesite (NiS2). The reduced partition function ratios of 60Ni/58Ni (103 lnβ60-58) for these minerals decrease in the order of polydymite > heazlewoodite > millerite > godlevskite > vaesite. Ni isotope fractionations in these Ni sulfides show an approximately linear dependence on the average Nisbnd S bond lengths, and have a significant negative correlation with the average Nisbnd Ni bond lengths. Furthermore, a change in Fe/Ni ratio can also lead to Ni isotope fractionation, and with substitution Fe for Ni, the reduced partition function ratios of 60Ni/58Ni decrease.

  11. New Isotope 263Hs

    Energy Technology Data Exchange (ETDEWEB)

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  12. Ustioni da fuoco / Burn injuries / Les brûlures

    Directory of Open Access Journals (Sweden)

    Liliana Copertino

    2008-04-01

    Full Text Available Severe burn injuries require high specialistic treatment. Burn injuries are common in disasters and war scenarios, so war medicine has been fundamental to improve treatment protocols for burn patients..Burn injuries are classified according to the etiopathogenetic agent (physical, chemical or radiation, that determines different anatomoisthologic aspects.An estimation of the depth and extension are fundamental for defining the gravity of the burn. Critical burn patients have to be transported in specialistic Centers. There they are treated by multispecialistic teams from the resuscitation phase to the reconstructive surgery and specialist rehabilitation.. This process can continue for two years with the objective to return patients to a quiet normal life. Les brûlures sont des lésions traumatiques qui requièrent un traitement spécialisé. Lors de catastrophes et de guerres, les brûlures sont des lésions très fréquentes et la médecine de guerre a contribué à faire avancer la science de manière importante, dans le traitement de cette pathologie.Les brûlures sont classées en fonction de l'agent étiopathogénique (agents physiques, chimiques ou radiations dont le mécanisme d'action qui provoque la lésion cause des aspects anatomohistologiques caractéristiques.Pour définir la sévérité d'une brûlure, il est aussi fondamental d'éstimer l'extension de la surface corporelle et la profondeur de l'épiderme, et éventuellement du derme, atteints. Les patients gravement brûlés doivent être hospitalisés dans des Centres Spécialisés où des équipes multispécialistes les suivent de la phase initiale de la réanimation aux phases de chirurgie reconstructive et au processus de réhabilitation. Ces dernières phases peuvent se prolonger pendant les deux années suivant le traumatisme avant qu'une réintégration dans une vie sociale acceptable ne puisse être faite.

  13. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  14. Closed Claim Query File

    Data.gov (United States)

    Social Security Administration — This file is used to hold information about disability claims that have been closed and have been selected for sampling.Sampling is the process whereby OQR reviews...

  15. Surgical wound care -- closed

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000738.htm Surgical wound care - closed To use the sharing features on ... made during surgery. It is also called a "surgical wound." Some incisions are small. Others are very long. ...

  16. "Brücke dreht sich um!". A Deconstructionist Reading of Kafka's "Die Brücke"

    Directory of Open Access Journals (Sweden)

    Eva Hoffmann

    2014-12-01

    Full Text Available Franz Kafka's (1883-1924 "Die Brücke" is one of the less well-known texts by one of the most prolific authors of literary modernity. However, this short prose text embodies prevalent questions of literary modernity and philosophy as it reflects the crisis of language in regard of identity, communication, and literary production. Placed in the context of fin-de-siècle's discourse of language crisis, this article provides a dialogue between Kafka's "Die Brücke" and Hannah Arendt's (1906-1975 philosophy of thinking and speaking in The Life of the Mind. Contrary to Arendt's understanding of the metaphor as "a carrying over" between the mental activities of the solitude thinker and a reconciliation with the pluralistic world shared with others, this article argues for a deconstructionist reading of "Die Brücke" as a tool to reevaluate Arendt's notion of a shared human experience ensured through language and illustrates the advantages of poetic texts within philosophical discourses.

  17. 75 FR 76624 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Models BR700-710A1-10; BR700-710A2...

    Science.gov (United States)

    2010-12-09

    ... Deutschland Ltd & Co KG Models BR700-710A1-10; BR700-710A2-20; and BR700-710C4-11 Turbofan Engines AGENCY....13 by adding the following new AD: 2010-25-05 Rolls-Royce Deutschland Ltd & Co KG (formerly Rolls-Royce Deutschland GmbH, formerly BMW Rolls-Royce GmbH): Amendment 39- 16538. Docket No. FAA-2010-0614...

  18. Gallium isotope fractionation during Ga adsorption on calcite and goethite

    Science.gov (United States)

    Yuan, Wei; Saldi, Giuseppe D.; Chen, JiuBin; Vetuschi Zuccolini, Marino; Birck, Jean-Louis; Liu, Yujie; Schott, Jacques

    2018-02-01

    Gallium (Ga) isotopic fractionation during its adsorption on calcite and goethite was investigated at 20 °C as a function of the solution pH, Ga aqueous concentration and speciation, and the solid to solution ratio. In all experiments Ga was found to be enriched in light isotopes at the solid surface with isotope fractionation △71Gasolid-solution up to -1.27‰ and -0.89‰ for calcite and goethite, respectively. Comparison of Ga isotopic data of this study with predictions for 'closed system' equilibrium and 'Rayleigh fractionation' models indicates that the experimental data are consistent with a 'closed system' equilibrium exchange between the fluid and the solid. The results of this study can be interpreted based on Ga aqueous speciation and the structure of Ga complexes formed at the solid surfaces. For calcite, Ga isotope fractionation is mainly triggered by increased Ga coordination and Ga-O bond length, which vary respectively from 4 and 1.84 Å in Ga(OH)4- to 6 and 1.94 Å in the >Ca-O-GaOH(OH2)4+ surface complex. For goethite, despite the formation of Ga hexa-coordinated >FeOGa(OH)20 surface complexes (Ga-O distances of 1.96-1.98 Å) both at acid and alkaline pH, a similar extent of isotope fractionation was found at acid and alkaline pH, suggesting that Ga(OH)4- is preferentially adsorbed on goethite for all investigated pH conditions. In addition, the observed decrease of Ga isotope fractionation magnitude observed with increasing Ga surface coverage for both calcite and goethite is likely related to the formation of Ga surface polymers and/or hydroxides with reduced Ga-O distances. This first study of Ga isotope fractionation during solid-fluid interactions suggests that the adsorption of Ga by oxides, carbonates or clay minerals could yield significant Ga isotope fractionation between secondary minerals and surficial fluids including seawater. Ga isotopes thus should help to better characterize the surficial biogeochemical cycles of gallium and its

  19. The application of inductively coupled plasma dynamic reaction cell mass spectrometry for measurement of selenium isotopes, isotope ratios and chromatographic detection of selenoamino acids

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt

    2000-01-01

    ratios was close to the theoretical values for selenium concentrations at 1 and 10 ng ml(-1). The accuracy of the isotope ratios, however, was improved by correcting the count rate of all selenium isotopes equivalent to the formation of SeH at 9.6 +/- 0.5% one mass unit above the selenium isotopes....... A linear relationship (r mass from the Se-80 reference isotope. This indicated that the error was caused by mass bias. The slope of the curve at -3.0% error per mass unit can be used for correction of the measured......Inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was characterised for the detection of the six naturally occurring selenium isotopes. The potentially interfering argon dimers at the selenium masses m/z 74, 76, 78 and 80 were reduced in intensity by approximately five...

  20. Isotopes, ice ages, and terminal Proterozoic earth history

    Science.gov (United States)

    Kaufman, Alan J.; Knoll, Andrew H.; Narbonne, Guy M.

    1997-01-01

    Detailed correlations of ancient glacial deposits, based on temporal records of carbon and strontium isotopes in seawater, indicate four (and perhaps five) discrete ice ages in the terminal Proterozoic Eon. The close and repeated stratigraphic relationship between C-isotopic excursions and glaciogenic rocks suggests that unusually high rates of organic carbon burial facilitated glaciation by reducing atmospheric greenhouse capacity. The emerging framework of time and environmental change contributes to the improved resolution of stratigraphic and evolutionary pattern in the early fossil record of animals. PMID:11038552

  1. Isotopes, ice ages, and terminal Proterozoic earth history.

    Science.gov (United States)

    Kaufman, A J; Knoll, A H; Narbonne, G M

    1997-06-24

    Detailed correlations of ancient glacial deposits, based on temporal records of carbon and strontium isotopes in seawater, indicate four (and perhaps five) discrete ice ages in the terminal Proterozoic Eon. The close and repeated stratigraphic relationship between C-isotopic excursions and glaciogenic rocks suggests that unusually high rates of organic carbon burial facilitated glaciation by reducing atmospheric greenhouse capacity. The emerging framework of time and environmental change contributes to the improved resolution of stratigraphic and evolutionary pattern in the early fossil record of animals.

  2. Tracing back sulfur isotope reequilibration due to contact metamorphism: A case study from the Perubar VMS deposit, Central Peru

    OpenAIRE

    Polliand, Marc; Fontboté, Lluis; Spangenberg, Jorge

    1999-01-01

    The mid-Cretaceous Perubar VMS deposit, Central Peru, affected by contact metamorphism, has been the subject of a sulfur isotope investigation. The measured δ34S values for sulfate-sulfide pairs from the deposit indicate that close to equilibrium isotopic reequilibration occurred during metamorphism. After “filtering” the contact metamorphism effect, sulfur isotope desiquilibrium trends for coexisting sulfate-sulfide pairs were obtained on the δ34S versus Δ34S diagram, indicating a mixing bet...

  3. Therapeutic use of radioactive isotopes

    CERN Multimedia

    Caroline Duc

    2013-01-01

    In December, researchers from ISOLDE-CERN, the Paul Scherrer Institute (PSI) and the Institut Laue-Langevin (ILL) published the results of an in vivo study which successfully proved the effectiveness of four terbium isotopes for diagnosing and treating cancerous tumours.   Four terbium isotopes suitable for clinical purposes. “ISOLDE is the only installation capable of supplying terbium isotopes of such purity and intensity in the case of three out of the four types used in this study,” explains Karl Johnson, a physicist at ISOLDE.  “Producing over a thousand different isotopes, our equipment offers the widest choice of isotopes in the world!” Initially intended for fundamental physics research, ISOLDE has diversified its activities over time to invest in various projects in the materials science, biochemistry and nuclear medicine fields. The proof-of-concept study has confirmed that the four terbium isotopes 149Tb, 152Tb, 155Tb produ...

  4. Ab Initio Potential Energy Surfaces for Both the Ground (X̃1A′ and Excited (A∼1A′′ Electronic States of HSiBr and the Absorption and Emission Spectra of HSiBr/DSiBr

    Directory of Open Access Journals (Sweden)

    Anyang Li

    2012-01-01

    Full Text Available Ab initio potential energy surfaces for the ground (X̃1A′ and excited (A˜A′′1 electronic states of HSiBr were obtained by using the single and double excitation coupled-cluster theory with a noniterative perturbation treatment of triple excitations and the multireference configuration interaction with Davidson correction, respectively, employing an augmented correlation-consistent polarized valence quadruple zeta basis set. The calculated vibrational energy levels of HSiBr and DSiBr of the ground and excited electronic states are in excellent agreement with the available experimental band origins. In addition, the absorption and emission spectra of HSiBr and DSiBr were calculated using an efficient single Lanczos propagation method and are in good agreement with the available experimental observations.

  5. Determining the effective Wilson coefficient a2 in terms of BR (Bs→ηcϕ ) and evaluating BR (Bs→ηcf0(980 ))

    Science.gov (United States)

    Ke, Hong-Wei; Li, Xue-Qian

    2017-09-01

    In this work, we investigate decays of Bs→ηcϕ and Bs→ηcf0(980 ) in a theoretical framework. The calculation is based on the postulation that f0(980 ) and f0(500 ) are mixtures of pure quark states 1/√{2 }(u ¯u +d ¯d ) and s ¯s . The hadronic matrix elements for Bs→ϕ and Bs→f0(980 ) are calculated in the light-front quark model and the important Wilson coefficient a2 which is closely related to nonperturbative QCD is extracted. However, our numerical results indicate that no matter how the mixing parameter is adjusted to reconcile contributions of f0(980 ) and f0(500 ), one cannot make the theoretical prediction on Bs→ηc+π+π- to meet the data. Moreover, the new measurement of BR (Bs→J /ψ +f0(500 ))<1.7 ×10-6 also negates the mixture scenario. Thus, we conclude that the recent data suggest that f0(980 ) is a four-quark state (tetraquark or K K ¯ molecule), at least the fraction of its pure quark constituents is small.

  6. ZnWO{sub 4} nanorods decorated with Ag/AgBr nanoparticles as highly efficient visible-light-responsive photocatalyst for dye AR18 photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kebin, E-mail: kebinlee314@gmail.com [College of Chemistry and Material Science, Key Laboratory of Synthetic and Natural Function Molecule Chemistry of Ministry of Education, Northwest University, Xi’an 710069 (China); Xue, Jie; Zhang, Yanhui [College of Chemistry and Material Science, Key Laboratory of Synthetic and Natural Function Molecule Chemistry of Ministry of Education, Northwest University, Xi’an 710069 (China); Wei, Hong [Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi’an University of Technology, Xi’an 710048 (China); Liu, Yalan; Dong, Chengxing [College of Chemistry and Material Science, Key Laboratory of Synthetic and Natural Function Molecule Chemistry of Ministry of Education, Northwest University, Xi’an 710069 (China)

    2014-11-30

    Graphical abstract: - Highlights: • Ag/AgBr-sensitized ZnWO{sub 4} nanorod heterojunction was fabricated and characterized. • The composite showed the enhanced visible-light activity for AR18 photodegradation. • The enhancement mechanism and the catalytic degradation mechanism were revealed. • The effects of various parameters on AR18 photodegradation kinetics were examined. - Abstract: A novel Ag-AgBr/ZnWO{sub 4} nanorod heterostructure composite was prepared via a facile deposition–precipitation method with ZnWO{sub 4} nanorods as the substrate, and characterized by XRD, SEM-EDX, TEM, XPS, and DRS to confirm its structure, morphology, composition, and optical property. The composite was used as a photocatalyst to destroy azo dye Acid Red 18 (AR18) under visible light irradiation. The effects of catalyst composition, solution pH, catalyst loading, and initial dye concentration on photocatalytic degradation rate and efficiency were examined. It was revealed that the photocatalytic activity of Ag-AgBr/ZnWO{sub 4} nanojunction system was higher than that of the single ZnWO{sub 4} or Ag-AgBr for AR18 degradation under visible light irradiation. The optimal content of Ag-AgBr in Ag-AgBr/ZnWO{sub 4} composite was 0.58:1 of Ag/W molar ratio using in the catalyst preparation. Acid pH and decreasing dye initial concentration were favorable to AR18 photodegradation, but the catalyst loading had an optimal value. The catalyst was stable and recyclable, after five successive cycles the photoactivity was fully maintained and the XRD patterns of AgBr displayed no evident change. Photoluminescence spectra revealed the enhanced photocatalytic activity and stability were closely related to the efficient separation of photogenerated carriers in Ag-AgBr/ZnWO{sub 4} nanojunction system. Superoxide radicals and holes were found to be main active species for AR18 photodegradation. Finally, the possible mechanism for AR18 degradation over Ag-AgBr/ZnWO{sub 4} nanorods under

  7. Improved Growth Methods for LaBr3 Scintillation Radiation Detectors

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S

    2011-05-01

    The objective is to develop advanced materials for deployment as high-resolution gamma ray detectors. Both LaBr3 and CeBr3 are advanced scintillation materials, and will be studied in this research. Prototype devices, in collaboration Sandia National Laboratories, will be demonstrated along with recommendations for mass production and deployment. It is anticipated that improved methods of crystal growth will yield larger single crystals of LaBr3 for deployable room-temperature operated gamma radiation spectrometers. The growth methods will be characterized. The LaBr3 and CeBr3 scintillation crystals will be characterized for light yield, spectral resolution, and for hardness.

  8. Unge kontanthjælpsmodtagere i Brøndby

    OpenAIRE

    Mikkelsen, Caroline; Buus, Anniqa Kristine; Larsen, Jonas; Larsen, Andreas Peter

    2013-01-01

    Welfare recipients in Brøndby are categorized into groups based on social- psychologically factors and their ability to work. This project will examine why youths are placed in group 2 and 3. In doing so, the project look at the different groups and analyze them in relation to the municipality’s policies on welfare. In its analysis, the project focuses on the social and economic dimensions but this is interplayed with the politics of the municipality. The project is orientated by its case stu...

  9. High-speed CuBr brightness amplifier beam profile

    Science.gov (United States)

    Evtushenko, G. S.; Torgaev, S. N.; Trigub, M. V.; Shiyanov, D. V.; Evtushenko, T. G.; Kulagin, A. E.

    2017-01-01

    This paper addresses the experimental study of the beam profile of the CuBr brightness amplifier operating at a wide range of pulse repetition frequencies. The use of a medium-size gas discharge tube (2 cm) ensures the operation of the brightness amplifier both at typical PRFs (520 kHz) and at higher PRFs (up to 100 kHz), either with or without HBr additive. The effect of the active additive on the beam profile is demonstrated. The testing results on kinetic modeling of radial processes in the laser (brightness amplifier) plasma are also discussed.

  10. Brüssel enne Moskvat / Markus Meckel, Matthias Wissmann

    Index Scriptorium Estoniae

    Meckel, Markus

    2005-01-01

    Saksa liiduparlamendi sotsiaaldemokraatide fraktsiooni liikme Markus Meckeli ja Saksa liiduparlamendi Euroopa komisjoni esimehe Matthias Wissmanni avaldus, milles nad kutsuvad tunnistama Balti riikide ajalugu ja korraldama päev enne Moskvas toimuvat Teise maailmasõja lõppu tähistavat üritust Brüsselis sõja lõpu 60. aastapäeva mälestusürituse. Artikkel ilmus samaaegselt ajalehtedes International Herald Tribune, Die Welt, Die Presse, Le Figaro, Gazeta Wyborcza, Lietuvas rytas, Diena

  11. Brújula electrónica basada en magnetoimpedancia

    OpenAIRE

    Martín Aguilar, Héctor

    2013-01-01

    Se desarrollara un prototipo funcional de brújula electronica utilizando un sensor de campo magnético de alta sensibilidad basado en el fenómeno de Magneto-Impedancia Gigante (GMI). El trabajo es eminentemente práctico y el alumno utilizará equipamiento científico disponible en los grupos de investigación del Departamento. Tiene componentes relacionadas con los materiales magnéticos, el diseño de circuitos electromagnéticos y la instrumentación y control.

  12. Adidas Suomi Oy: Brändikuvan rakentaminen markkinoinnin keinoin

    OpenAIRE

    Leinonen, Miira

    2015-01-01

    Tämä opinnäytetyö tehtiin toimeksiantona Adidas Suomi Oy:lle syksyllä 2014. Opinnäytetyön tavoitteena oli selvittää muotialan mielipidevaikuttajien mielikuvat Adidaksesta ja sen merkittävimmistä kilpailijoista. Vertailtaviksi brändeiksi valittiin kuusi tärkeintä kilpailijaa, jotka ovat Converse, Karhu, New Balance, Nike, Puma ja Reebok. Opinnäytetyön toimeksiantaja Adidas Suomi Oy on osa kansainvälistä Adidas Group konsernia. Yritys on yksi maailman tunnetuimmista urheilumerkeistä ja toim...

  13. Taxonomic revision of Asian genus Glyptopetalum Thwaites (Celastraceae R. Br.

    Directory of Open Access Journals (Sweden)

    Ivan A. Savinov

    2014-12-01

    Full Text Available Taxonomic survey of Asian genus Glyptopetalum Thwaites (Celastraceae R. Br. is presented. Thirty five species taxa of Glyptopetalum are accepted, including one new species, G.  vidalii I. Savinov (Laos, Thailand, a new record for China, G. tonkinense Pitard (SE Yunnan and a new record for Cambodia,               G. quadrangulare Prain ex King, a new record for Indonesia – G. euonymoides Merr. and a new record for Philippines, Mindanao island – G. loheri Merr. 

  14. New Eudesmane Sesquiterpenoids from Salvia plebeia R. Br.

    Science.gov (United States)

    Ma, Lie-Feng; Wang, Peng-Fei; Wang, Ji-Dong; Tong, Xiang-Min; Shan, Wei-Guang; Zhang, Hui; Zhan, Zha-Jun

    2017-08-01

    Three new sesquiterpenoids, salplebeones A - C (1 - 3), were isolated from the ethanol-soluble extract of the aerial part of Salvia plebeia R. Br. Their structures were established by detailed analysis of NMR and MS spectra. Salplebeone A was an eudesmane lactone, while salplebeones B and C were rare eudesmane sesquiterpenoids, containing 12,8-lactam groups. Antiproliferative activities of salplebeones A - C to myeloid leukemia cell lines were evaluated. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  15. Propiconazole is a specific and accessible brassinosteroid (BR biosynthesis inhibitor for Arabidopsis and maize.

    Directory of Open Access Journals (Sweden)

    Thomas Hartwig

    Full Text Available Brassinosteroids (BRs are steroidal hormones that play pivotal roles during plant development. In addition to the characterization of BR deficient mutants, specific BR biosynthesis inhibitors played an essential role in the elucidation of BR function in plants. However, high costs and limited availability of common BR biosynthetic inhibitors constrain their key advantage as a species-independent tool to investigate BR function. We studied propiconazole (Pcz as an alternative to the BR inhibitor brassinazole (Brz. Arabidopsis seedlings treated with Pcz phenocopied BR biosynthetic mutants. The steady state mRNA levels of BR, but not gibberellic acid (GA, regulated genes increased proportional to the concentrations of Pcz. Moreover, root inhibition and Pcz-induced expression of BR biosynthetic genes were rescued by 24epi-brassinolide, but not by GA(3 co-applications. Maize seedlings treated with Pcz showed impaired mesocotyl, coleoptile, and true leaf elongation. Interestingly, the genetic background strongly impacted the tissue specific sensitivity towards Pcz. Based on these findings we conclude that Pcz is a potent and specific inhibitor of BR biosynthesis and an alternative to Brz. The reduced cost and increased availability of Pcz, compared to Brz, opens new possibilities to study BR function in larger crop species.

  16. Closing global material loops

    DEFF Research Database (Denmark)

    Prosman, Ernst-Jan; Wæhrens, Brian Vejrum; Liotta, Giacomo

    2017-01-01

    Replacing virgin materials with waste materials, a practice known as Industrial Symbiosis (IS), has been identified as a key strategy for closing material loops. This article adopts a critical view on geographic proximity and external coordinators – two key enablers of IS. By ‘uncovering’ a case...... for geographic proximity and external coordinators. In doing so, our insights into firm-level challenges of long-distance IS exchanges contribute to closing global material loops by increasing the number of potential circular pathways....

  17. Chromatographic hydrogen isotope separation

    Science.gov (United States)

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  18. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  19. ISOTOPE FRACTIONATION PROCESS

    Science.gov (United States)

    Clewett, G.H.; Lee, DeW.A.

    1958-05-20

    A new method is described for isotopic enrichment of uranium. It has been found that when an aqueous acidic solution of ionic tetravalent uraniunn is contacted with chelate complexed tetravalent uranium, the U/sup 238/ preferentially concentrates in the complexed phase while U/sup 235/ concentrates in the ionic phase. The effect is enhanced when the chelate compound is water insoluble and is dissolved in a water-immiscible organic solvent. Cupferron is one of a number of sultable complexing agents, and chloroform is a suitable organic solvent.

  20. Isotope Production and Distribution Program. Financial statements, September 30, 1994 and 1993

    Energy Technology Data Exchange (ETDEWEB)

    Marwick, P.

    1994-11-30

    The attached report presents the results of the independent certified public accountants` audit of the Isotope Production and Distribution (IP&D) Program`s financial statements as of September 30, 1994. The auditors have expressed an unqualified opinion on IP&D`s 1994 statements. Their reports on IP&D`s internal control structure and on compliance with laws,and regulations are also provided. The charter of the Isotope Program covers the production and sale of radioactive and stable isotopes, byproducts, and related isotope services. Prior to October 1, 1989, the Program was subsidized by the Department of Energy through a combination of appropriated funds and isotope sales revenue. The Fiscal Year 1990 Appropriations Act, Public Law 101-101, authorized a separate Isotope Revolving Fund account for the Program, which was to support itself solely from the proceeds of isotope sales. The initial capitalization was about $16 million plus the value of the isotope assets in inventory or on loan for research and the unexpended appropriation available at the close of FY 1989. During late FY 1994, Public Law 103--316 restructured the Program to provide for supplemental appropriations to cover costs which are impractical to incorporate into the selling price of isotopes. Additional information about the Program is provided in the notes to the financial statements.

  1. Influence of Halogen Variation on Structure and Interactions in Vinyl Halide (H_2C=CHX)\\cdotsCO_2 (x = F, Cl, Br) Complexes

    Science.gov (United States)

    Anderton, Ashley M.; Christenholz, Cori L.; Dorris, Rachel E.; Peebles, Rebecca A.; Peebles, Sean A.

    2016-06-01

    Chirped-pulse and resonant cavity Fourier-transform microwave spectroscopy have been used to investigate dimers of CO_2 with vinyl fluoride (VF), vinyl chloride (VCl) and vinyl bromide (VBr). For all three complexes, CO_2 is aligned adjacent to the X-C-H end (X = F, Cl, Br) of the ethylene subunit, with C-X\\cdotsC and C-H\\cdotsO contacts. For VF\\cdotsCO_2, a second isomer is also observed, with CO_2 roughly parallel to the H-C=C-F side of VF; however, there is no spectroscopic indication that similar structures are present for VCl\\cdotsCO_2 or VBr\\cdotsCO_2. For vinyl fluoride\\cdotsCO_2, a full structural analysis has previously been published, while for the Cl- and Br-containing species, insufficient data are presently available for complete structure determinations. However, structural information from ab initio calculations, 35Cl/37Cl and 79B/81Br isotopic substitution, and analysis of chlorine and bromine nuclear quadrupole coupling constants will be presented. In addition, for this series of dimers containing C-H\\cdotsO contacts, further insight into the nature of the weak interactions may be obtained from Quantum Theory of Atoms in Molecules (QTAIM) and other ab initio} analyses that are presently in progress. C. L. Christenholz, R. E. Dorris, R. A. Peebles, S. A. Peebles, J. Phys. Chem. A, 118, (2014), 8765-8772.

  2. Natural Organobromine in Marine Sediments: New Evidence of Biogeochemical Br Cycling

    Energy Technology Data Exchange (ETDEWEB)

    A Leri; J Hakala; M Marcus; A Lanzirotti; C Reddy; S Myneni

    2011-12-31

    Organobromine (Br{sub org}) compounds, commonly recognized as persistent, toxic anthropogenic pollutants, are also produced naturally in terrestrial and marine systems. Several enzymatic and abiotic bromination mechanisms have been identified, as well as an array of natural Br{sub org} molecules associated with various marine organisms. The fate of the carbon-bromine functionality in the marine environment, however, remains largely unexplored. Oceanographic studies have noted an association between bromine (Br) and organic carbon (C{sub org}) in marine sediments. Even so, there has been no direct chemical evidence that Br in the sediments exists in a stable form apart from inorganic bromide (Br{sub inorg}), which is widely presumed conservative in marine systems. To investigate the scope of natural Br{sub org} production and its fate in the environment, we probed Br distribution and speciation in estuarine and marine sediments using in situ X-ray spectroscopy and spectromicroscopy. We show that Br{sub org} is ubiquitous throughout diverse sedimentary environments, occurring in correlation with C{sub org} and metals such as Fe, Ca, and Zn. Analysis of sinking particulate carbon from the seawater column links the Br{sub org} observed in sediments to biologically produced Br{sub org} compounds that persist through humification of natural organic matter (NOM). Br speciation varies with sediment depth, revealing biogeochemical cycling of Br between organic and inorganic forms as part of the burial and degradation of NOM. These findings illuminate the chemistry behind the association of Br with Corg in marine sediments and cast doubt on the paradigmatic classification of Br as a conservative element in seawater systems.

  3. SoLid: Search for Oscillations with Lithium-6 Detector at the SCK-CEN BR2 reactor

    Science.gov (United States)

    Ban, G.; Beaumont, W.; Buhour, J. M.; Coupé, B.; Cucoanes, A. S.; D'Hondt, J.; Durand, D.; Fallot, M.; Fresneau, S.; Giot, L.; Guillon, B.; Guilloux, G.; Janssen, X.; Kalcheva, S.; Koonen, E.; Labare, M.; Moortgat, C.; Pronost, G.; Raes, L.; Ryckbosch, D.; Ryder, N.; Shitov, Y.; Vacheret, A.; Van Mulders, P.; Van Remortel, N.; Weber, A.; Yermia, F.

    2016-04-01

    Sterile neutrinos have been considered as a possible explanation for the recent reactor and Gallium anomalies arising from reanalysis of reactor flux and calibration data of previous neutrino experiments. A way to test this hypothesis is to look for distortions of the anti-neutrino energy caused by oscillation from active to sterile neutrino at close stand-off (˜ 6- 8m) of a compact reactor core. Due to the low rate of anti-neutrino interactions the main challenge in such measurement is to control the high level of gamma rays and neutron background. The SoLid experiment is a proposal to search for active-to-sterile anti-neutrino oscillation at very short baseline of the SCK•CEN BR2 research reactor. This experiment uses a novel approach to detect anti-neutrino with a highly segmented detector based on Lithium-6. With the combination of high granularity, high neutron-gamma discrimination using 6LiF:ZnS(Ag) and precise localization of the Inverse Beta Decay products, a better experimental sensitivity can be achieved compared to other state-of-the-art technology. This compact system requires minimum passive shielding allowing for very close stand off to the reactor. The experimental set up of the SoLid experiment and the BR2 reactor will be presented. The new principle of neutrino detection and the detector design with expected performance will be described. The expected sensitivity to new oscillations of the SoLid detector as well as the first measurements made with the 8 kg prototype detector deployed at the BR2 reactor in 2013-2014 will be reported.

  4. Measurement of the ratio of branching fractions BR( B 0→K*γ BR( B s 0→ϕγ ${{BR({B^0} o K*gamma } over {BR(B_s^0 o phi gamma }}$

    Directory of Open Access Journals (Sweden)

    Daria Savrina

    2012-06-01

    Full Text Available The interest to the rare radiative decays of the B-mesons at LHCb is mostly aroused due to the measurement of the photon polarization in the Bs0 → ϕγ decay, which may provide a sensitive probe for the Standard Model. The LHCb experiment has started to take data at the energy of √s = 7 TeV in 2010 and the current paper presents the result of the studies of the two rare radiative decays B0 → K*γ and Bs0 → ϕγ with 340 pb−1 of data taken in the first half of 2011. With this data we have a preliminary measurement of BR(B0→K*γBR(Bs0→ϕγ ${{BRleft({{B^0} o K*gamma} ight} over {BRleft({B_s^0 o phi gamma} ight}}$ = 1.52±0.14(stat.±0.10(syst.±0.12(fs/fd and assuming the measured value of B $mathcal{B}$ (B0 → K*γ = (4.33 ± 0.15 × 10.5 we infer B $mathcal{B}$ (Bs0 → ϕγ = (2.8 ± 0.5 × 10−5 [1

  5. Water-resistant, monodispersed and stably luminescent CsPbBr3/CsPb2Br5 core-shell-like structure lead halide perovskite nanocrystals

    Science.gov (United States)

    Qiao, Bo; Song, Pengjie; Cao, Jingyue; Zhao, Suling; Shen, Zhaohui; Gao, Di; Liang, Zhiqin; Xu, Zheng; Song, Dandan; Xu, Xurong

    2017-11-01

    Lead halide perovskite materials are thriving in optoelectronic applications due to their excellent properties, while their instability due to the fact that they are easily hydrolyzed is still a bottleneck for their potential application. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb2Br5 were obtained using a modified non-stoichiometric solution-phase method. CsPb2Br5 2D layers were coated on the surface of CsPbBr3 nanocrystals and formed a core-shell-like structure in the synthetic processes. The stability of the luminescence of the CsPbBr3 nanocrystals in water and ethanol atmosphere was greatly enhanced by the photoluminescence-inactive CsPb2Br5 coating with a wide bandgap. The water-stable enhanced nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.

  6. Pb isotope composition in lichens and aerosols from eastern Sicily: Insights into the regional impact of volcanoes on the environment

    Energy Technology Data Exchange (ETDEWEB)

    Monna, F. (Institut FA Forel (Switzerland)); Aiuppa, A.; Varrica, D. (Dipt. C.F.T.A., Palermo (Italy)); Dongarra, G. (Dipt. C.F.T.A., Palermo (Italy) CNR, Palermo (Italy). Istituto Geochimica dei Fluidi)

    1999-08-01

    A total of 25 lichen thalli of Parmelia conspersa (Ehrh), collected at Vulcano island and at Mt. Etna, during a one-year biogeochemical survey, were analyzed for Pb, br, Al, Sc,[sup 206]Pb/[sup 207]Pb, and [sup 208]Pb/[sup 206]Pb ratios. Lead isotope ratios were also measured on aerosol samples from urban areas and industrial sites of Sicily. The observed [sup 206]Pb/[sup 207]Pb range for urban and industrial aerosols matches the anthropogenic signature. Lichens instead, are closer to the compositional field of [sup 206]Pb rich geogenic sources. This natural input is more evident at Vulcano island than at Mt. Etna, where the anthropogenic activities are considerably more effective. On the basis of lead isotope data, Pb/Br ratios and calculated lead enrichment factors, a natural lead pollution from volcanoes is suggested. Volcanic lead contribution ranges from 10 to 30% at Mt. Etna to 10--80% at Vulcano island.

  7. Method of separating boron isotopes

    Science.gov (United States)

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  8. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...... with calcium carbonate in order to test the reliability of the Cr carbonate compositions. Several experimental approaches have been employed to elucidate the fractionation behavior of Cr isotopes when Cr(VI) is incorporated into calcium carbonate phases. These results indicate that at lower Cr concentrations......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...

  9. Urban water - a new frontier in isotope hydrology.

    Science.gov (United States)

    Ehleringer, James R; Barnette, Janet E; Jameel, Yusuf; Tipple, Brett J; Bowen, Gabriel J

    2016-01-01

    Isotope hydrology has focused largely on landscapes away from densely inhabited regions. In coming decades, it will become increasingly more important to focus on water supplies and dynamics within urban systems. Stable isotope analyses provide important information to water managers within large cities, particularly in arid regions where evaporative histories of water sources, vulnerabilities, and reliabilities of the water supplies can be major issues. Here the spatial and vertical understanding of water supporting urban systems that comes from stable isotope analyses can serve as a useful management tool. We explore this research frontier using the coupled natural-human landscape of the Salt Lake Valley, USA, with its greater than one million inhabitants. We first provide data on the stable isotope ratios of the hydrologic system's primary components: precipitation, incoming surface waters, and terminus waters in this closed basin. We then explore the spatial and temporal patterns of drinking waters within the urban landscape and the new opportunities to better link isotope ratio data with short- and long-term management interests of water managers.

  10. Mercury isotope compositions in North American forest soils and litters

    Science.gov (United States)

    Zheng, W.; Obrist, D.; Bergquist, B. A.

    2013-12-01

    Soils represent one of the largest reservoirs of mercury on Earth, playing a critical role in the natural cycle of mercury by acting as both a sink and source. However, it is not well understood how soils sequestrate and remobilize Hg. Natural variations in stable Hg isotopes are being explored as a promising tool in studying the transformation and transport of Hg. However, Hg isotopic data in soils is scarce. In addition, the limited isotopic data that exists is significantly different from those of atmospheric Hg, which is one of the major sources of Hg to soils. For example, Hg mass independent fractionation (MIF, typically reported as Δ199Hg) is positive in atmospheric wet deposition, but most soils display negative Δ199Hg. MIF on 200Hg (Δ200Hg) is also observed in atmospheric wet deposition, but not in soils. The discrepancy between soils and atmospheric samples is still unexplained. In this study, we surveyed the Hg isotope compositions in soil profiles, litters and fresh vegetation from four different forest sites across United States (Thompson forest, WA, Truckee, CA, Niwot Ridge, CO and Howland, MA). The current results from the WA site show that soils primarily display negative mass dependent fractionation for the even isotopes (MDF, reported as δ202Hg) with values for δ202Hg of up to -2.0‰. Significant MIF for both odd isotopes is also observed in all WA soil samples and Δ199Hg is mostly negative (up to -0.4‰). No MIF on 200Hg is observed in these soils. The negative Δ199Hg in soils is inconsistent with the positive Δ199Hg reported in atmospheric wet deposition, suggesting that either Hg transformations within or on the surface of soils and/or plants alter its isotope composition after deposition or other types of Hg deposition (e.g., Hg(0) or Hg(II) dry deposition) is more predominant. The Δ199Hg/Δ201Hg ratio is close to 1 in the soils, which is consistent with the results of laboratory photochemical reduction of inorganic Hg

  11. Classification of Chinese Honeys According to Their Floral Origins Using Elemental and Stable Isotopic Compositions.

    Science.gov (United States)

    Wu, Zhaobin; Chen, Lanzhen; Wu, Liming; Xue, Xiaofeng; Zhao, Jing; Li, Yi; Ye, Zhihua; Lin, Guanghui

    2015-06-10

    The objective of this study is to test the feasibility of multi-isotopic and elemental analyses combined with chemometric techniques for differentiating the botanical origins of major honey products in China. The stable isotope and elemental compositions of 57 honey samples from four major floral origins in China (i.e., rape honey, acacia honey, vitex honey, and jujube honey) were analyzed using stable isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results showed that hydrogen and oxygen isotopes could be more suitable than the carbon isotope for discriminating the floral origins of major honeys in China. There were significant differences in the contents of most elements between or among different floral origins. The combination of IRMS and ICP-MS methods provides the most effective and accurate approach (in most cases close to 100% accuracy) for classifying Chinese honeys according to their floral origins.

  12. Total Absorption Gamma-Ray Spectroscopy of 87Br, 88Br and 94Rb Beta-Delayed Neutron Emitters

    CERN Document Server

    Valencia, E; Algora, A; Agramunt, J; Rubio, B; Rice, S; Gelletly, W; Regan, P; Zakari-Issoufou, A -A; Fallot, M; Porta, A; Rissanen, J; Eronen, T; Aysto, J; Batist, L; Bowry, M; Bui, V M; Caballero-Folch, R; Cano-Ott, D; Elomaa, V -V; Estevez, E; Farrelly, G F; Garcia, A R; Gomez-Hornillos, B; Gorlychev, V; Hakala, J; Jordan, M D; Jokinen, A; Kolhinen, V S; Kondev, F G; Martinez, T; Mendoza, E; Moore, I; Penttila, H; Podolyak, Zs; Reponen, M; Sonnenschein, V; Sonzogni, A A

    2016-01-01

    We investigate the decay of 87Br, 88Br and 94Rb using total absorption gamma-ray spectroscopy. These important fission products are beta-delayed neutron emitters. Our data show considerable gamma-intensity, so far unobserved in high-resolution gamma-ray spectroscopy, from states at high excitation energy. We also find significant differences with the beta intensity that can be deduced from existing measurements of the beta spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component for 235U fission at cooling times in the range 1 to 100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for gamma emission from neutron unbound s...

  13. Precision measurement of the ratio BR(K→π+π-e+e-)/BR(K→π+π-πD0)

    Science.gov (United States)

    NA48/1 Collaboration; Batley, J. R.; Kalmus, G. E.; Lazzeroni, C.; Munday, D. J.; Patel, M.; Slater, M. W.; Wotton, S. A.; Arcidiacono, R.; Bocquet, G.; Ceccucci, A.; Cundy, D.; Doble, N.; Falaleev, V.; Gatignon, L.; Gonidec, A.; Grafström, P.; Kubischta, W.; Marchetto, F.; Mikulec, I.; Norton, A.; Panzer-Steindel, B.; Rubin, P.; Wahl, H.; Goudzovski, E.; Hristov, P.; Kekelidze, V.; Kozhuharov, V.; Litov, L.; Madigozhin, D.; Molokanova, N.; Potrebenikov, Yu.; Stoynev, S.; Zinchenko, A.; Monnier, E.; Swallow, E. C.; Winston, R.; Sacco, R.; Walker, A.; Baldini, W.; Dalpiaz, P.; Frabetti, P. L.; Gianoli, A.; Martini, M.; Petrucci, F.; Savrié, M.; Scarpa, M.; Calvetti, M.; Collazuol, G.; Iacopini, E.; Ruggiero, G.; Bizzeti, A.; Lenti, M.; Veltri, M.; Behler, M.; Eppard, K.; Eppard, M.; Hirstius, A.; Kleinknecht, K.; Koch, U.; Marouelli, P.; Masetti, L.; Moosbrugger, U.; Morales Morales, C.; Peters, A.; Wanke, R.; Winhart, A.; Dabrowski, A.; Fonseca Martin, T.; Szleper, M.; Velasco, M.; Anzivino, G.; Imbergamo, E.; Lamanna, G.; Lubrano, P.; Michetti, A.; Nappi, A.; Piccini, M.; Valdata-Nappi, M.; Cenci, P.; Pepe, M.; Petrucci, M. C.; Cerri, C.; Fantechi, R.; Mannelli, I.; Costantini, F.; Fiorini, L.; Giudici, S.; Pierazzini, G.; Sozzi, M.; Cheshkov, C.; Chèze, J. B.; de Beer, M.; Debu, P.; Gouge, G.; Marel, G.; Mazzucato, E.; Peyaud, B.; Vallage, B.; Holder, M.; Maier, A.; Ziolkowski, M.; Biino, C.; Cartiglia, N.; Clemencic, M.; Lopez, S. Goy; Menichetti, E.; Pastrone, N.; Wislicki, W.; Dibon, H.; Jeitler, M.; Markytan, M.; Neuhofer, G.; Widhalm, L.

    2011-01-01

    The K→π+π-e+e- decay mode was investigated using the data collected in 2002 by the NA48/1 Collaboration. With about 23 k K→π+π-e+e- events and 59 k K→π+π-πD0 normalization decays, the K→π+π-e+e- branching ratio relative to the K→π+π-πD0 one was determined to be BR(K→π+π-e+e-)/BR(K→π+π-πD0)=(3.28±0.06±0.04)×10-2. This result was used to set the upper limit |g/g|<3.0 at 90% CL on the presence, in the decay amplitude, of an E1 direct emission (g) term relative to the dominant inner bremsstrahlung (g) term. The CP-violating asymmetry A in the sinϕcosϕ distribution of K→π+π-e+e- events, where ϕ is the angle between the π+π- and the e+e- decay planes in the kaon centre of mass, was found to be A=(-0.4±0.8)%, consistent with zero. These results are in good agreement with a description of the K→π+π-e+e- decay amplitude dominated by the CP-even inner bremsstrahlung process.

  14. Estimating Stratospheric and Tropospheric BrO columns using GEOSCCM and the Ozone Monitoring Instrument

    Science.gov (United States)

    Liang, Q.; Chance, K.; Suleiman, R. M.; Zhang, Y.

    2013-12-01

    Atmospheric BrO is an important gas - despite its very low abundance of parts per trillion, and it plays an important chemical role in the destruction of ozone in the troposphere and the stratosphere. The current atmospheric BrO abundance estimates are highly uncertain due to significant uncertainties in the contribution of very-short-lived (VSL) bromocarbons, in contrast to the well-quantified contribution from the long-lived bromine-containing compounds, i.e. Halons and CH3Br. This is particularly true in the troposphere with various measurements suggesting the presence of a global background BrO from 0.5 ppt to 2 ppt, and, locally, BrO can be as high as 30 ppt in the Arctic and Antarctic marine boundary layer. We will run a 10-year model simulation between 2001-2010 using the NASA GEOS Chemistry Climate Model (GEOSCCM) V2 which contains a detailed stratospheric chemistry coupled with an interactive VSL bromocarbon chemistry. BrO in the troposphere will be relaxed to monthly mean BrO fields previously archived during a GEOS-Chem full chemistry simulation. The simulated VSL bromocarbons and BrO from both models have been extensively evaluated and compare well with aircraft, balloon-borne and GOME-2 satellite observations. We will analyze the model simulated BrO together with satellite BrO measurements from the Ozone Monitoring Instrument (OMI) to address the following three questions: 1) How much BrO is present in the stratosphere and the troposphere? 2) What is the relative contribution of the stratosphere and the troposphere to total atmospheric BrO column abundance? 3) What drives the seasonal and geographical variability of stratospheric and tropospheric BrO columns?

  15. Rare-isotope and kinetic studies of Pt/SnO2 catalysts

    Science.gov (United States)

    Upchurch, Billy T.; Wood, George M.; Schryer, David R.; Hess, Robert V.; Miller, Irvin M.; Kielin, Erik J.

    1990-01-01

    Closed-cycle pulsed CO2 laser operation requires the use of an efficient CO-O2 recombination catalyst for these dissociation products which otherwise would degrade the laser operation. The catalyst must not only operate at low temperatures but also must operate efficiently for long periods. In the case of the Laser Atmospheric Wind Sounder (LAWS) laser, an operational lifetime of 3 years is required. Additionally, in order to minimize atmospheric absorption and enhance aerosol scatter of laser radiation, the LAWS system will operate at 9.1 micrometers with an oxygen-18 isotope CO2 lasing medium. Consequently, the catalyst must not only operate at low temperatures but must also preserve the isotopic integrity of the rare-isotope composition in the recombination mode. Several years ago an investigation of commercially available and newly synthesized recombination catalysts for use in closed-cycle pulsed common and rare-isotope CO2 lasers was implemented at the NASA Langley Research Center. Since that time, mechanistic efforts utilizing both common and rare oxygen isotopes have been implemented and continue. Rare-isotope studies utilizing commercially available platinum-tin oxide catalyst have demonstrated that the catalyst contributes oxygen-16 to the product carbon dioxide thus rendering it unusable for rare-isotope applications. A technique has been developed for modification of the surface of the common-isotope catalyst to render it usable. Results of kinetic and isotope label studies using plug flow, recycle plug flow, and closed internal recycle plug flow reactor configuration modes are discussed.

  16. Nutrition chez le brûlé

    Science.gov (United States)

    Perro, G.

    2016-01-01

    Summary La nutrition est un challenge chez le brûlé, paradigme de l’agressé. Les points importants sont les apports entéraux précoces par sonde gastrique voire post pyloriques, la position proclive > 30°, la surveillance du transit et sa régulation par gastro ou entéro-kinétiques, la surveillance du poids, la quantification des apports avec supplémentation parentérale en cas de retard protéino énergétique. Chez l’enfant, l’adhésion à l’alimentation est difficile, de même que chez le senior, où une évaluation nutritionnelle initiale dépiste souvent une dénutrition préexistante. Les compléments alimentaires seront largement prescrits chez les patients de gravité intermédiaire. Les obèses bénéficieront d’un régime hypocalorique et hyperprotidique. Chez l’insuffisant rénal non dialysé il convient de limiter les apports en potassium. En cas brûlure périnéale, on peut proposer soit une constipation de courte durée, soit la mise en place d’un entéro-collecteur, les indications de colostomie étant devenues rares. Les apports entéraux sont difficiles à gérer en cas de décubitus ventral pour SDRA. Chez le brûlé grave de réanimation, l’accent doit plus être mis sur la qualité des nutriments que sur leur quantité. Les anciennes formules d’estimation calorique conduisaient à une surnutrition difficile à administrer et en général mal tolérée; la quantification mesurée par calorimétrie indirecte ou estimée par la formule de Toronto est bien plus adaptée. Plus récemment, l’instauration d’une immunonutrition (supplémentation en vitamines et oligo-éléments, glutamine, arginine, acide Ω 3 et contrôle raisonné de la glycémie) a été proposée pour réduire le stress oxydatif et l’inflammation provoqués par l’accident. PMID:27857647

  17. Closed timelike curves

    CERN Document Server

    Thorne, K S

    1993-01-01

    This lecture reviews recent research on closed timelike curves (CTCS), including these questions: Do the laws of physics prevent CTCs from ever forming in classical spacetime? If so, by what physical mechanism are C'I‘Cs prevented? Can the laws of physics be adapted in any reasonable way to a. spacetime that contains C'I‘Cs, or do they necessarily give nonsense? What insights into quantum gravity can one gain by asking questions such as these?

  18. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

    Science.gov (United States)

    Munksgaard, Niels C; Zwart, Costijn; Kurita, Naoyuki; Bass, Adrian; Nott, Jon; Bird, Michael I

    2015-01-01

    The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.

  19. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

    Directory of Open Access Journals (Sweden)

    Niels C Munksgaard

    Full Text Available The isotope signatures registered in speleothems during tropical cyclones (TC provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.

  20. Estimering af brændstofforbrug vha. GPS Data

    DEFF Research Database (Denmark)

    Andersen, Ove; Lahrmann, Harry; Torp, Kristian

    2010-01-01

    Det er simpelt og billigt at opsamle GPS målinger fra køretøjer. Når større mængder GPS data indsamles fra et passende antal køretøjer kan dataen bruges til at beregne f.eks. køretider. Det er ligeledes muligt ud fra GPS data at estimere miljøindikatorer så som, hvor aggressivt kører bilister og er...... der nogle vejstrækninger, der har en højere (negativ) miljø påvirkning end andre? I denne artikel præsenterer et forsøg, hvor GPS data anvendes til at estimere brændstofforbruget ved en enkelt tur og for vejnettet generelt. Dette gøres ved at opbygge en database med GPS data. Ud fra disse data gives...

  1. Bovins et humains au Brésil en 2007

    Directory of Open Access Journals (Sweden)

    Hervé Théry

    2008-03-01

    Full Text Available On recherche 35 millions de bovins… Selon les données récemment publiées par l’IBGE (Censo Agropecuário 2006, Resultados preliminares le Brésil comptait en 2006 un peu moins de 170 millions de têtes de bétail, alors que selon la Pesquisa Pecuária Municipal, du même IBGE et à la même date, le pays en comptait alors près de 206 millions.Sans chercher pour le moment la cause de cette différence – de méthodologie, très probablement – et en se rappelant que l’IBGE avertit que ces données provisoi...

  2. Polyvinylpolypyrrolidone Supported Brønsted Acidic Catalyst for Esterification

    Directory of Open Access Journals (Sweden)

    Song Wang

    2016-01-01

    Full Text Available A polyvinylpolypyrrolidone (PVPP supported Brønsted acidic catalyst ([PVPP-BS]HSO4 was prepared by coupling SO3H-functionalized polyvinylpolypyrrolidone with H2SO4 in this work. After the characterization through FT-IR, FESEM, TG, BET, and elemental analysis, it was found that 1,4-butane sultone (BS and sulfuric acid reacted with PVPP and were immobilized on PVPP surface. The prepared [PVPP-BS]HSO4 catalyst shows high catalytic activity for a series of esterification reactions and could be separated from the reacted mixture easily. Moreover, this catalyst could be recycled and reused for six times without significant loss of catalytic performance.

  3. Alocação de linhagens de milho derivadas das populações BR-105 e BR-106 em grupos heteróticos Allocation of maize lines from BR-105 and BR-106 populations to heterotic groups

    Directory of Open Access Journals (Sweden)

    Rogério de Melo Costa Pinto

    2001-09-01

    Full Text Available Os grupos heteróticos são importantes no melhoramento de milho, pois permitem o uso mais eficiente do germoplasma. Assim, o objetivo deste trabalho foi alocar linhagens de milho em grupos heteróticos a partir de estimativas da capacidade específica de combinação. Oito linhagens S3 da população BR-105 e dez da BR-106, foram cruzadas ao nível interpopulacional seguindo um sistema dialélico. Oitenta híbridos simples foram obtidos e avaliados em látices em três ambientes. Foram avaliados os caracteres produção de grãos (PG, altura da planta (AP e altura da espiga (AE. As estimativas das capacidades geral (CGC e específica (CEC de combinação foram obtidas segundo o método 4, modelo I de Griffing. A partir das estimativas de CEC, as linhagens foram alocadas aos respectivos grupos heteróticos utilizando-se o método UPGMA (média aritmética não ponderada para a construção do dendrograma e a dispersão gráfica pelo método das coordenadas principais. Para PG, as linhagens foram alocadas em quatro grupos heteróticos, sendo dois grupos em cada população. Para AP e AE, o uso das estimativas de CEC não foi eficiente para alocar as linhagens em grupos heteróticos. As análises de agrupamento e de coordenadas principais foram eficientes na alocação das linhagens em grupos heteróticos para PG. Então, como a produção de grãos é a principal característica para o melhoramento de milho, com a alocação das linhagens em quatro grupos heteróticos, os cruzamentos serão direcionados e o processo de melhoramento se tornará mais eficiente, evitando a obtenção e a avaliação de cruzamentos (híbridos desnecessários.The heterotic groups are important in maize breeding programs because they allow the most efficient use of the germoplasm. The objective of this research was to allocate maize lines to heterotic groups from estimates of specific combining ability (SCA. Eight and ten S3 lines derived from populations BR-105 and BR

  4. Competition from Isotopic Modelling

    Directory of Open Access Journals (Sweden)

    Virginie Fabre

    2011-01-01

    Full Text Available During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.

  5. (C5H12NCu2Br3: A Piperidinium Copper(I Bromide with [Cu2Br3]− Ladders

    Directory of Open Access Journals (Sweden)

    Karl W. Krämer

    2012-10-01

    Full Text Available Piperidinium copper(I bromide, (C5H12NCu2Br3, was obtained from a solution of CuBr2, piperidine, and HBr in ethanol. At 60 °C ethanol slowly reduces copper(II to copper(I. Colorless plates of (C5H12NCu2Br3 crystallize in the triclinic space group P-1 with lattice parameters of a = 6.2948(10 Å, b = 8.2624(14 Å, c = 10.7612(17 Å, α = 75.964(19°, β = 89.232(19°, γ = 84.072(19°, and Z = 2 at 173 K. [CuBr4] tetrahedra share edges and form [Cu2Br3]− ladders parallel to the a-axis. (C5H12N+ ions adopt a chair conformation and connect the [Cu2Br3]− ladders via H-bonding. The (C5H12NCu2Br3 structure is related to the mineral rasvumite, KFe2S3, space group Cmcm, which is isostructural to several alkali copper(I halides.

  6. Photodegradation of Methyl Orange Using Magnetically Recoverable AgBr@Ag3PO4/Fe3O4 Photocatalyst under Visible Light

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2014-01-01

    Full Text Available A novel magnetically recoverable AgBr@Ag3PO4/Fe3O4 hybrid was prepared by a simple deposition-precipitation approach and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and UV-Vis diffuse reflectance spectroscopy (DRS. The results revealed that the photocatalytic activity and stability of AgBr@Ag3PO4/Fe3O4 composite toward decomposition of methyl orange (MO dye were superior to those of pure Ag3PO4 under visible light irradiation. The photocatalytic activity enhancement of AgBr@Ag3PO4/Fe3O4 is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between Ag3PO4 and AgBr, as well as the good conductivity of Fe3O4. Moreover, the photocatalyst could be easily separated by applying an external magnetic field due to its magnetic property. The quenching effects of different scavengers proved that active h+ and played the major role for the MO degradation. This work would provide new insight for the construction of visible light responsible photocatalysts with high performance, good stability, and recoverability.

  7. Microbes: Agents of Isotopic Change

    Science.gov (United States)

    Fogel, M. L.

    2012-12-01

    Microbes drive many of the important oxidation and reduction reactions on Earth; digest almost all forms of organic matter; and can serve as both primary and secondary producers. Because of their versatile biochemistry and physiology, they impart unique isotopic signatures to organic and inorganic materials, which have proven to be key measurements for understanding elemental cycling now and throughout Earth's history. Understanding microbial isotope fractionations in laboratory experiments has been important for interpreting isotopic patterns measured in natural settings. In fact, the pairing of simple experiment with natural observation has been the pathway for interpreting the fingerprint of microbial processes in ancient sediments and rocks. Examples of how key experiments have explained stable isotope fractionations by microbes and advanced the field of microbial ecology will be presented. Learning the isotopic signatures of Earth's microbes is a valuable exercise for predicting what isotopic signatures could be displayed by possible extant or extinct extraterrestrial life. Given the potential for discovery on Mars, Enceladus, and other solar system bodies, new methods and techniques for pinpointing what is unique about microbial isotope signatures is particularly relevant.

  8. Cationic P-S-X cages (X=Br, I).

    Science.gov (United States)

    Gonsior, Marcin; Krossing, Ingo; Matern, Eberhard

    2006-02-08

    The first condensed-phase preparation of ternary P-Ch-X cations (Ch=O-Te, X=F-I) is reported: [P5S3X2]+, [P5S2X2]+, and [P4S4X]+ (X=Br, I). [P5S3X2]+ is formed from the reaction of the Ag+/PX3 reagent with P4S3. The [P5S3X2]+ ions have a structure that is related to P4S5 by replacing P=S by P+--X and S in the four-membered ring by P(X). We provide evidence that the active ingredient of the Ag+/PX3 reagent is the (H2CCl2)Ag-X-PX2+ cation. The latter likely reacts with the HOMO of P4S3 in a concerted HOMO-LUMO addition to give the P5S3X2+ ion as the first species visible in situ in the low-temperature 31P NMR spectrum. The [P5S3X2]+ ions are metastable at -78 degrees C and disproportionate at slightly higher temperatures to give [P5S2X2]+ and [P4S4X]+, probably with the extrusion of 1/n (PX)n (X=Br, I). All six new cage compounds have been characterized by multinuclear NMR spectroscopy and, in part, by IR or Raman spectroscopy. The [P5S2X2]+ salts have a nortricyclane skeleton and were also characterized by X-ray crystallography. The structure of the [P4S4X]+ ion is related to that of P4S5 in that the exo-cage P=S bond is replaced by an isoelectronic P+--X moiety.

  9. Pan-Balti bränding - müüt või tegelikkus? / Joel Volkov

    Index Scriptorium Estoniae

    Volkov, Joel, 1972-

    2006-01-01

    Brändil pole kodumaad, on keel ja päritolumaa. Lokaalsed brändid valivad suhtlemiseks kohalikega nende kodukeele, globaalsed brändid harilikult inglise keele. Üks suuremaid ja tugevamaid lokaalsest süsteemist kasvanud Pan-Balti brände on Hansapank. Lisa: Sulev Vedler. Hansast võib saada Swedbank

  10. Program plan for the Brayton Isotope Power System. Phase I. Design, fabrication and test of the Brayton Isotope Power System

    Energy Technology Data Exchange (ETDEWEB)

    Longee, H. W.

    1975-10-22

    Phase I of an overall program for the development of a 500 to 2000 W(e) (EOM), 7-y life, power system for space vehicles is discussed. The system uses a closed Brayton dynamic system to convert energy from an isotope heat source at a net efficiency greater than 25 percent. This first phase, a 35-month effort, is for the conceptual design of a 1300 W(e), 450 lb flight system and the design, fabrication, and test of a ground demonstration system. The flight system will use, for the baseline design, two of the multihundred-watt (MHW) heat sources being developed. The Ground Demonstration System will simulate, as closely as possible, the Brayton Isotope Power Flight System and will utilize components and technology being developed for the Mini-Brayton rotating unit, recuperator and heat source assembly, respectively. The Ground Demonstration System includes a performance test and a 1000-h endurance test.

  11. Characterization of non-classical Csbnd Br⋯π interactions in (E)-1,3-dibromo-5-(2-(ferrocenyl)vinyl)benzene and related derivatives of ferrocene

    Science.gov (United States)

    Shukla, Rahul; Panini, Piyush; McAdam, C. John; Robinson, Brian H.; Simpson, Jim; Tagg, Tei; Chopra, Deepak

    2017-03-01

    Amongst the halogens, the involvement of bromine atoms in various types of intermolecular interactions is comparatively the least studied. In this manuscript, we report the formation of Csbnd Br⋯π interactions, with the π-rings being the cyclopentadienyl (Cp) rings of a ferrocene molecule in a newly synthesized compound (E)-1,3-dibromo-5-(2-(ferrocenyl)vinyl)benzene. We have also performed a detailed quantitative analysis on Csbnd Br⋯π interactions observed in the synthesized molecule and in several related molecules found in the Cambridge Structure Database (CSD) showing the presence of these interactions. A topological analysis based upon QTAIM theory and electrostatic potential ESP mapped on the Hirshfeld surface of these molecules confirm that these interactions are better described as "halogen bonds" wherein the electropositive region (σ-hole) on the Br-atom interacts with the electronegative region over the Cp-ring of the ferrocene. Further, the electronegative region on the bromine atom (perpendicular to the Csbnd Br bond) was observed to be involved in the formation of highly directional Csbnd H⋯Br interactions with the ∠Csbnd Br⋯H close to 90°. Thus the bromine atom is acting as both a "halogen bond donor" and "hydrogen bond acceptor" in the crystal packing with the two interactions being mutually orthogonal.

  12. Isotopic disproportionation during hydrogen isotopic analysis of nitrogen-bearing organic compounds

    Science.gov (United States)

    Nair, Sreejesh; Geilmann, Heike; Coplen, Tyler B.; Qi, Haiping; Gehre, Matthias; Schimmelmann, Arndt; Brand, Willi A.

    2015-01-01

    Rationale High-precision hydrogen isotope ratio analysis of nitrogen-bearing organic materials using high-temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H2) has been suspected as a possible cause of incomplete H2 yield and hydrogen isotopic fractionation. Methods The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400 °C, have been compared using a selection of nitrogen-bearing organic compounds, including caffeine. A focus of the experiments was to avoid or suppress hydrogen cyanide (HCN) formation and to reach quantitative H2 yields. The technique also was optimized to provide acceptable sample throughput. Results The classical HTC reaction of a number of selected compounds exhibited H2 yields from 60 to 90 %. Yields close to 100 % were measured for the experiments with the chromium-enhanced reactor. The δ2H values also were substantially different between the two types of experiments. For the majority of the compounds studied, a highly significant relationship was observed between the amount of missing H2and the number of nitrogen atoms in the molecules, suggesting the pyrolytic formation of HCN as a byproduct. A similar linear relationship was found between the amount of missing H2 and the observed hydrogen isotopic result, reflecting isotopic fractionation. Conclusions The classical HTC technique to produce H2 from organic materials using high temperatures in the presence of glassy carbon is not suitable for nitrogen-bearing compounds. Adding chromium to the reaction zone improves the yield to 100 % in most cases. The initial formation of HCN is accompanied by a strong hydrogen isotope effect, with the observed hydrogen isotope results on H2 being substantially shifted to more negative δ2H values. The reaction can be understood as an initial disproportionation leading to H2 and HCN

  13. Reaction Kinetics of HBr with HO2: A New Channel for Isotope Scrambling Reactions.

    Science.gov (United States)

    Church, Jonathan R; Skodje, Rex T

    2016-11-03

    The gas phase reaction kinetics of HBr with the HO2 radical are investigated over the temperature range of T = 200-1500 K using a theoretical approach based on transition state theory. The parameters for the potential energy surface are computed using density functional theory with the M11 exchange functional. The rate coefficient for the HBr + HO2 → Br + H2O2 abstraction channel is found to be somewhat larger than previous estimates at low temperatures due to quantum tunneling. The present study reveals the existence of a novel exchange pathway, HBr + H'O2 → H'Br + HO2, which exhibits a much lower reaction barrier than does the abstraction route. The transition state for this process is a symmetrical planar five-membered-ring-shaped structure. At low temperatures, this concerted double hydrogen transfer reaction is several orders of magnitude faster than the abstraction channel. The exchange process may be observed using isotope scrambling reactions; such reactions may contribute to observed isotope abundances in the atmosphere. The rate coefficients for the isotopically labeled reactions are computed.

  14. Inhibition of hydrogen oxidation by HBr and Br2

    DEFF Research Database (Denmark)

    Dixon-Lewis, Graham; Marshall, Paul; Ruscic, Branko

    2012-01-01

    O. Ab initio calculations were used to obtain rate coefficients for selected reactions of HBr and HOBr, and the hydrogen/bromine/oxygen reaction mechanism was updated. The resulting model was validated against selected experimental data from the literature and used to analyze the effect of HBr and Br2......The high-temperature bromine chemistry was updated and the inhibition mechanisms involving HBr and Br2 were re-examined. The thermochemistry of the bromine species was obtained using the Active Thermochemical Tables (ATcT) approach, resulting in improved data for, among others, Br, HBr, HOBr and Br...... on laminar, premixed hydrogen flames. Our work shows that hydrogen bromide and molecular bromine act differently as inhibitors in flames. For HBr, the reaction HBr+H⇌H2+Br (R2) is rapidly equilibrated, depleting HBr in favor of atomic Br, which is the major bromine species throughout the reaction zone...

  15. The superacid HBr/AlBr(3) : protonation of benzene and ordered crystal structure of [C(6)H(7)](+)[Al(2)Br(7)](-).

    Science.gov (United States)

    Scholz, Franziska; Himmel, Daniel; Eisele, Lea; Unkrig, Wiebke; Krossing, Ingo

    2014-02-03

    Crystalline and properly ordered protonated benzene as the [C6 H7 ](+) [Al2 Br7 ](-) ⋅(C6 H6 ) salt 1 are obtained by the combination of solid AlBr3 , benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X-Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Critères de gravité des brûlures: à propos de 337 cas de brûlés au ...

    African Journals Online (AJOL)

    L'objectif était d'étudier les critères de gravité des brûlures chez des patients brûlés hospitalisés à l'hôpital militaire d'instruction Mohamed V de Rabat. Il s'agit d'une étude rétrospective qui concernait 337 patients hospitalisés de 2004 à 2010. Les variables étudiés sont: l'âge, la surface corporelle brûlée, la profondeur, ...

  17. Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI

    Science.gov (United States)

    Anderson, Christopher P.; Spears, Kenneth G.; Wilson, Kaitlynn R.; Sension, Roseanne J.

    2013-11-01

    It is well known that ultraviolet photoexcitation of halomethanes results in halogen-carbon bond cleavage. Each halogen-carbon bond has a dominant ultraviolet (UV) absorption that promotes an electron from a nonbonding halogen orbital (nX) to a carbon-halogen antibonding orbital (σ*C-X). UV absorption into specific transitions in the gas phase results primarily in selective cleavage of the corresponding carbon-halogen bond. In the present work, broadband ultrafast UV-visible transient absorption studies of CH2BrI reveal a more complex photochemistry in solution. Transient absorption spectra are reported spanning the range from 275 nm to 750 nm and 300 fs to 3 ns following excitation of CH2BrI at 266 nm in acetonitrile, 2-butanol, and cyclohexane. Channels involving formation of CH2Br + I radical pairs, iso-CH2Br-I, and iso-CH2I-Br are identified. The solvent environment has a significant influence on the branching ratios, and on the formation and stability of iso-CH2Br-I. Both iso-CH2Br-I and iso-CH2I-Br are observed in cyclohexane with a ratio of ˜2.8:1. In acetonitrile this ratio is 7:1 or larger. The observation of formation of iso-CH2I-Br photoproduct as well as iso-CH2Br-I following 266 nm excitation is a novel result that suggests complexity in the dissociation mechanism. We also report a solvent and concentration dependent lifetime of iso-CH2Br-I. At low concentrations the lifetime is >4 ns in acetonitrile, 1.9 ns in 2-butanol and ˜1.4 ns in cyclohexane. These lifetimes decrease with higher initial concentrations of CH2BrI. The concentration dependence highlights the role that intermolecular interactions can play in the quenching of unstable isomers of dihalomethanes.

  18. Compelling Research Opportunities using Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

  19. On forge des partenariats au Brésil | CRDI - Centre de recherches ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    9 mai 2011 ... La collaboration entre les différents établissements brésiliens reconnus dans leur champ d'expertise donne du poids aux arguments quand il s'agit de s'adresser aux décideurs, conclut Mme Padua. Instituto de Pesquisas Ecologicas, Brésil Fundação Oswaldo Cruz (FIOCRUZ), Brésil Faculté de médecine ...

  20. Photochromic conversions of the Br/sub 2//sup -/ radical ion

    Energy Technology Data Exchange (ETDEWEB)

    Plyusnin, V.F.

    The photolysis of frozen solutions of HBr, containing complexes of FeBr/sub 3/ or CuBr/sub 4//sup 2 -/, is discussed. The primary product of the photoreduction of complexes is the radical ion Br/sub 2//sup -/. Irradiation in the absorption band of this particle leads to its disappearance. However, it can be regulated by photolysis of the sample in a shorter-wave region of the spectrum. The processes leading to this photochrome conversion are discussed.

  1. Babcock and Wilcox BR-100 100-ton rail/barge spent fuel shipping cask

    Energy Technology Data Exchange (ETDEWEB)

    None

    1990-02-01

    This Preliminary Design Report (PDR) provides a detailed description of the design, analyses, and testing programs for the BR-100 cask. The BR-100 is a Type B(U) cask designed for transport by rail or barge. This report presents the preliminary analyses and tests which have been performed for the BR-100 and outlines the confirmatory analyses and tests which will be performed.

  2. Iron isotope characteristics of Hot Springs at Chocolate Pots, Yellowstone National Park.

    Science.gov (United States)

    Wu, Lingling; Brucker, Rebecca Poulson; Beard, Brian L; Roden, Eric E; Johnson, Clark M

    2013-11-01

    Chocolate Pots Hot Springs in Yellowstone National Park is a hydrothermal system that contains high aqueous ferrous iron [∼0.1 mM Fe(II)] at circumneutral pH conditions. This site provides an ideal field environment in which to test our understanding of Fe isotope fractionations derived from laboratory experiments. The Fe(III) oxides, mainly produced through Fe(II) oxidation by oxygen in the atmosphere, have high ⁵⁶Fe/⁵⁴Fe ratios compared with the aqueous Fe(II). However, the degree of fractionation is less than that expected in a closed system at isotopic equilibrium. We suggest two explanations for the observed Fe isotope compositions. One is that light Fe isotopes partition into a sorbed component and precipitate out on the Fe(III) oxide surfaces in the presence of silica. The other explanation is internal regeneration of isotopically heavy Fe(II) via dissimilatory Fe(III) reduction farther down the flow path as well as deeper within the mat materials. These findings provide evidence that silica plays an important role in governing Fe isotope fractionation factors between reduced and oxidized Fe. Under conditions of low ambient oxygen, such as may be found on early Earth or Mars, significantly larger Fe isotope variations are predicted, reflecting the more likely attainment of Fe isotope equilibrium associated with slower oxidation rates under low-O₂ conditions.

  3. Link between Enhanced Arctic tropospheric BrO observed by Aura OMI and meteorological conditions

    Science.gov (United States)

    Choi, S.; Joiner, J.; Theys, N.; Salawitch, R. J.; Wales, P.; Canty, T. P.; Chance, K.; Suleiman, R. M.; Palm, S. P.; Cullather, R. I.; Darmenov, A.; da Silva, A.; Kurosu, T. P.

    2015-12-01

    Bromine radicals (Br + BrO) are important species owing to the ability to destroy ozone catalytically. They may also impact oxidative pathways of many trace gases including dimethylsulfide (DMS) and mercury. Bromine monoxide (BrO) is the most commonly observed bromine radical species. Since it absorbs ultraviolet (UV) radiation, it can be observed using remote sensing technique including Differential Optical Absorption Spectroscopy (DOAS). Previous studies have reported rapid enhancements tropospheric BrO (so called "bromine explosion") connected to near-surface ozone depletion events during springtime in the Arctic. Space-based observation of BrO through Ozone Monitoring Instrument (OMI) is an excellent tool for studying bromine chemistry particularly for the Arctic due to its frequent observations at high latitudes. We derive tropospheric columns BrO by subtracting estimates of stratospheric column BrO from OMI total column BrO and air mass factor (AMF) correction, and analyze the tropospheric columns BrO in conjunction with Modern-Era Retrospective analysis for Research and Application (MERRA) meteorological fields provided by NASA Global Modeling and Assimilation Office (GMAO) in order to investigate a link between bromine explosion and near-surface meteorological factors.

  4. [Oxidation of mercury by CuBr2 decomposition under controlled-release membrane catalysis condition].

    Science.gov (United States)

    Hu, Lin-Gang; Qu, Zan; Yan, Nai-Qiang; Guo, Yong-Fu; Xie, Jiang-Kun; Jia, Jin-Ping

    2014-02-01

    CuBr2 in the multi-porous ceramic membrane can release Br2 at high temperature, which was employed as the oxidant for Hg0 oxidation. Hg0 oxidation efficiency was studied by a membrane catalysis device. Meanwhile, a reaction and in situ monitoring device was designed to avoid the impact of Br2 on the downstream pipe. The result showed that the MnO(x)/alpha-Al2O3 catalysis membrane had a considerable "controlled-release" effect on Br2 produced by CuBr2 decomposition. The adsorption and reaction of Hg0 and Br2 on the surface of catalysis membrane obeyed the Langmuir-Hinshelwood mechanism. The removal efficiency of Hg0 increased with the rising of Br2 concentration. However, when Br2 reached a certain concentration, the removal efficiency was limited by adsorption rate and reaction rate of Hg0 and Br2 on the catalysis membrane. From 473 K to 573 K, the variation of Hg0 oxidation efficiency was relatively stable. SO2 in flue gas inhibited the oxidation of Hg0 while NO displayed no obvious effect.

  5. Closed Strings From Nothing

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, Albion

    2001-07-25

    We study the physics of open strings in bosonic and type II string theories in the presence of unstable D-branes. When the potential energy of the open string tachyon is at its minimum, Sen has argued that only closed strings remain in the perturbative spectrum. We explore the scenario of Yi and of Bergman, Hori and Yi, who argue that the open string degrees of freedom are strongly coupled and disappear through confinement. We discuss arguments using open string field theory and worldsheet boundary RG flows, which seem to indicate otherwise. We then describe a solitonic excitation of the open string tachyon and gauge field with the charge and tension of a fundamental closed string. This requires a double scaling limit where the tachyon is taken to its minimal value and the electric field is taken to its maximum value. The resulting flux tube has an unconstrained spatial profile; and for large fundamental string charge, it appears to have light, weakly coupled open strings living in the core. We argue that the flux tube acquires a size or order {alpha}' through sigma model and string coupling effects; and we argue that confinement effects make the light degrees of freedom heavy and strongly interacting.

  6. Isotope-based quantum information

    CERN Document Server

    G Plekhanov, Vladimir

    2012-01-01

    The present book provides to the main ideas and techniques of the rapid progressing field of quantum information and quantum computation using isotope - mixed materials. It starts with an introduction to the isotope physics and then describes of the isotope - based quantum information and quantum computation. The ability to manipulate and control electron and/or nucleus spin in semiconductor devices provides a new route to expand the capabilities of inorganic semiconductor-based electronics and to design innovative devices with potential application in quantum computing. One of the major challenges towards these objectives is to develop semiconductor-based systems and architectures in which the spatial distribution of spins and their properties can be controlled. For instance, to eliminate electron spin decoherence resulting from hyperfine interaction due to nuclear spin background, isotopically controlled devices are needed (i.e., nuclear spin-depleted). In other emerging concepts, the control of the spatial...

  7. Isotope Geochronology: Models Versus Reality

    National Research Council Canada - National Science Library

    Jan Burchart

    2015-01-01

    Majority of the papers on isotopic dating of minerals and rocks have been devoted to some new geochronological data important for geology or to developments of apparatus and improvements of laboratory...

  8. Production of medically useful bromine isotopes via alpha-particle induced nuclear reactions

    Science.gov (United States)

    Breunig, Katharina; Scholten, Bernhard; Spahn, Ingo; Hermanne, Alex; Spellerberg, Stefan; Coenen, Heinz H.; Neumaier, Bernd

    2017-09-01

    The cross sections of α-particle induced reactions on arsenic leading to the formation of 76,77,78Br were measured from their respective thresholds up to 37 MeV. Thin sediments of elemental arsenic powder were irradiated together with Al degrader and Cu monitor foils using the established stacked-foil technique. For determination of the effective α-particle energies and of the effective beam current through the stacks the cross-section ratios of the monitor nuclides 67Ga/66Ga were used. This should help resolve discrepancies in existing literature data. Comparison of the data with the available excitation functions shows some slight energy shifts as well as some differences in curve shapes. The calculated thick target yields indicate, that 77Br can be produced in the energy range Eα = 25 → 17 MeV free of isotopic impurities in quantities sufficient for medical application.

  9. Production of medically useful bromine isotopes via alpha-particle induced nuclear reactions

    Directory of Open Access Journals (Sweden)

    Breunig Katharina

    2017-01-01

    Full Text Available The cross sections of α-particle induced reactions on arsenic leading to the formation of 76,77,78Br were measured from their respective thresholds up to 37 MeV. Thin sediments of elemental arsenic powder were irradiated together with Al degrader and Cu monitor foils using the established stacked-foil technique. For determination of the effective α-particle energies and of the effective beam current through the stacks the cross-section ratios of the monitor nuclides 67Ga/66Ga were used. This should help resolve discrepancies in existing literature data. Comparison of the data with the available excitation functions shows some slight energy shifts as well as some differences in curve shapes. The calculated thick target yields indicate, that 77Br can be produced in the energy range Eα = 25 → 17 MeV free of isotopic impurities in quantities sufficient for medical application.

  10. Structural and electronic properties of silicene on MgX2 (X = Cl, Br, and I)

    KAUST Repository

    Zhu, Jiajie

    2014-07-23

    Silicene is a monolayer of Si atoms in a two-dimensional honeycomb lattice, being expected to be compatible with current Si-based nanoelectronics. The behavior of silicene is strongly influenced by the substrate. In this context, its structural and electronic properties on MgX2 (X = Cl, Br, and I) have been investigated using first-principles calculations. Different locations of the Si atoms are found to be energetically degenerate because of the weak van der Waals interaction with the substrates. The Si buckling height is below 0.55 Å, which is close to the value of free-standing silicene (0.49 Å). Importantly, the Dirac cone of silicene is well preserved on MgX2 (located slightly above the Fermi level), and the band gaps induced by the substrate are less than 0.1 eV. Application of an external electric field and stacking can be used to increase the band gap. © 2014 American Chemical Society.

  11. First fossil evidence of Connaraceae R. Br. from Indian Cenozoic and its phytogeographical significance

    Science.gov (United States)

    Khan, Mahasin Ali; Bera, Subir

    2016-07-01

    Fossil leaflet impression described here as a new species Rourea miocaudata sp. nov., showing close resemblance with the modern leaflets of Rourea caudata Planch. (Connaraceae R. Br.), has been recorded from the lower part of the Siwalik sediments (Dafla Formation, middle-upper Miocene) exposed at the road-cutting section of Pinjoli area in West Kameng district, Arunachal Pradesh. The important morphological characters of the fossil are its narrow elliptic leaflet, cuneate base, long caudate apex, entire margin, eucamptodromous to brochidodromous secondary veins, presence of intersecondary veins, percurrent and reticulate tertiary veins and orthogonally reticulate quaternary veins. This is the first authentic record of the occurrence of leaflet comparable to R. caudata of Connaraceae from the Cenozoic sediments of India and abroad. At present R. caudata does not grow in India and is restricted only in southeast Asia especially in China and Myanmar. This taxon probably migrated to these southeast Asian regions after lower Siwalik sedimentation (middle-upper Miocene) due to climatic change caused by post-Miocene orogenic movement of the Himalaya. The recovery of this species and other earlier-described evergreen taxa from the same formation, suggests the existence of a tropical, warm and humid climatic conditions during the depositional period.

  12. Stable Chlorine Isotope Fractionation

    Science.gov (United States)

    Sharp, Z.

    2006-12-01

    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  13. Nqrs Data for Al2BrH6LiO6 [Al2LiBr(OH)6] (Subst. No. 0056)

    Science.gov (United States)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for Al2BrH6LiO6 [Al2LiBr(OH)6] (Subst. No. 0056)

  14. NY-BR-1 Antigen Expression and anti-NY-BR-1 IgG in Egyptian Breast Cancer Patients: Clinicopathological and Prognostic Significance.

    Science.gov (United States)

    Abu El-Nazar, Salma Y; Ghazy, Amany A; Ghoneim, Hossam E; Zoheir, Malak; Ahmed, Ahmed S; Sorour, Sally S; Abouelella, Amira M

    2015-01-01

    Breast cancer is the most common gynecological malignancy in the world. In Egypt, it ranks the first among female malignancies with incidence of 37.7%. Over the last decades, the integration of prognostic and predictive markers in treatment decisions has led to more individualized and optimized therapy. NY-BR-1 antigen has been shown to be frequently expressed in breast cancers. The study aimed to assess the tissue expression of NY-BR-1 antigen and serum IgG antibody to this antigen in Egyptian breast cancer females. The study was conducted on 60 females (10 healthy, 10 having benign breast lesions, 40 with malignant breast cancer). NY-BR-1 Ag expression was evaluated by immunohistochemistry and anti-NY-BR-1 IgG was assessed by ELISA. Results revealed a significant difference in NY-BR-1 Ag expression between benign and malignant breast cancer patients. There was a significant correlation between NY-BR-1 antigen expression and estrogen receptor's status (P = 0.019), stage of the disease (P = 0.008), menopausal status (P = 0.008), lymph node involvement (P = 0.022) and anti-NY-BR-1 IgG (P = 0.032) among the studied individuals. In addition, there was a statistically significant increase in anti-NY-BR-1 IgG O.D. results among malignant breast cancer group. It is correlated with tumor type (P 1) and progesterone receptor status (P = 0.038). In conclusion, our work may represent a step towards identification of a new prognostic marker specific for breast cancer.

  15. Nitrogen isotope and mass balance approach in the Elbe Estuary

    Science.gov (United States)

    Sanders, Tina; Wankel, Scott D.; Dähnke, Kirstin

    2017-04-01

    The supply of bioavailable nitrogen is crucial to primary production in the world's oceans. Especially in estuaries, which act as a nutrient filter for coastal waters, microbial nitrogen turnover and removal has a particular significance. Nitrification as well as other nitrogen-based processes changes the natural abundance of the stable isotope, which can be used as proxies for sources and sinks as well as for process identification. The eutrophic Elbe estuary in northern Germany is loaded with fertilizer-derived nitrogen, but management efforts have started to reduce this load effectively. However, an internal nitrate source in turn gained in importance and the estuary changed from a sink to a source of dissolved inorganic nitrogen: Nitrification is responsible for significant estuarine nutrient regeneration, especially in the Hamburg Port. In our study, we aimed to quantify sources and sinks of nitrogen based on a mass and stable isotope budget in the Elbe estuary. A model was developed reproduce internal N-cycling and associated isotope changes. For that approach we measured dissolved inorganic nitrogen (DIN), particulate nitrogen and their stable isotopes in a case study in July 2013. We found an almost closed mass balance of nitrogen, with only low lost or gains which we attribute to sediment resuspension. The isotope values of different DIN components and the model approach both support a high fractionation of up to -25‰ during nitrification. However, the nitrogen balance and nitrogen stable isotopes suggest that most important processes are remineralization of organic matter to ammonium and further on the oxidation to nitrate. Denitrification and nitrate assimilation play a subordinate role in the Elbe Estuary.

  16. Seasonal variability of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in a temperate lake system

    Science.gov (United States)

    Loomis, Shannon E.; Russell, James M.; Heureux, Ana M.; D'Andrea, William J.; Sinninghe Damsté, Jaap S.

    2014-11-01

    Quantitative climate reconstructions are crucial for understanding the magnitude of and mechanisms behind natural and anthropogenic climate change, yet there are few proxies that can reliably reconstruct terrestrial temperature. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are increasingly used to reconstruct paleotemperature from lake sediments, but despite their potential, we have a poor understanding of (1) autochthonous vs. allochthonous sources of brGDGTs in lakes and (2) the seasonality of and environmental controls on brGDGT production within lakes. To investigate these factors, we examined water column suspended particulate matter (SPM) and settling particles from a sediment trap collected on a biweekly to monthly basis over a period of three years at Lower King Pond, a small kettle lake in northern Vermont, USA. We also compared the concentration and fractional abundances of brGDGTs in SPM and settling particles with those of catchment soils, river sediments, and lake surface sediments to constrain the relative importance of brGDGTs derived from the landscape versus brGDGTs produced within the lake itself. We find significant differences in concentrations and fractional abundances of brGDGTs between soil and river sediment samples from the catchment and lake sediments, indicating a mostly autochthonous source for lacustrine brGDGTs. BrGDGT concentrations, fluxes, and fractional abundances in SPM vary over the annual cycle, indicating that brGDGTs are produced throughout the year and respond to changes within the water column. The total annual flux of brGDGTs settling through the water column is comparable to the brGDGT accumulation rates in surface sediments, indicating that in this lake brGDGTs are mostly produced within the water column, not in the sediment itself. While brGDGTs are produced in all seasons within the water column, the flux to the sediments is highest during periods of spring and fall

  17. Science policy up close

    CERN Document Server

    Marburger, John H

    2015-01-01

    In a career that included tenures as president of Stony Brook University, director of Brookhaven National Laboratory, and science advisor to President George W. Bush, John Marburger (1941 2011) found himself on the front line of battles that pulled science ever deeper into the political arena. From nuclear power to global warming and stem cell research, science controversies, he discovered, are never just about science. Science Policy Up Close" presents Marburger s reflections on the challenges science administrators face in the twenty-first century. In each phase of public service Marburger came into contact with a new dimension of science policy. The Shoreham Commission exposed him to the problem of handling a volatile public controversy over nuclear power. The Superconducting Super Collider episode gave him insights into the collision between government requirements and scientists expectations and feelings of entitlement. The Directorship of Brookhaven taught him how to talk to the public about the risks ...

  18. Artificial photosynthesis: closing remarks.

    Science.gov (United States)

    Hammarström, Leif

    2017-06-02

    This paper derives from my closing remarks lecture at the 198th Faraday Discussion meeting on Artificial Photosynthesis, Kyoto, Japan, February 28-March 2. The meeting had sessions on biological approaches and fundamental processes, molecular catalysts, inorganic assembly catalysts, and integration of systems for demonstrating realistic devices. The field has had much progress since the previous Faraday Discussion on Artificial Photosynthesis in Edinburgh, UK, in 2011. This paper is a personal account of recent discussions and developments in the field, as reflected in and discussed during the meeting. First it discusses the general directions of artificial photosynthesis and some considerations for a future solar fuels technology. Then it comments on some scientific directions in the area of the meeting.

  19. Jealousy and Relationship Closeness

    Directory of Open Access Journals (Sweden)

    Mark Attridge

    2013-02-01

    Full Text Available This study confirmed a hypothesis from the Emotion-in-Relationships conceptual model, which predicts that greater interdependence between relationship partners—or closeness—creates the potential for jealousy. The study also sought to better define the positive side of romantic jealousy in addition to its more negative attributes. College students in premarital relationships (N = 229 completed a questionnaire, including 27 different measures and the Multidimensional Jealousy Scale. Select data were obtained from 122 cases at 3-month follow-up. Each jealousy scale was tested for associations with demographic (age, sex, and race, person (life satisfaction, loneliness, romantic attachment styles, love styles, and romantic beliefs, and relationship (affective, closeness, and social exchange theory constructs. Results clearly distinguished emotional/reactive jealousy as mostly “good” and cognitive/suspicious jealousy as “bad.” Behavioral jealousy was associated with few measures. Implications are discussed for the interdependence model of relationships and the transactional model of jealousy.

  20. Electron linac for medical isotope production with improved energy efficiency and isotope recovery

    Science.gov (United States)

    Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

    2015-09-08

    A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

  1. First measurement of beta decay half-lives in neutron-rich Tl and Bi isotopes

    Science.gov (United States)

    Benzoni, G.; Morales, A. I.; Valiente-Dobón, J. J.; Gottardo, A.; Bracco, A.; Camera, F.; Crespi, F. C. L.; Corsi, A. M.; Leoni, S.; Million, B.; Nicolini, R.; Wieland, O.; Gadea, A.; Lunardi, S.; Boutachkov, P.; Bruce, A. M.; Górska, M.; Grebosz, J.; Pietri, S.; Podolyak, Zs.; Pfützner, M.; Regan, P. H.; Weick, H.; Alcántara Núñez, J.; Algora, A.; Al-Dahan, N.; de Angelis, G.; Ayyad, Y.; Alkhomashi, N.; Allegro, P. R. P.; Bazzacco, D.; Benlliure, J.; Bowry, M.; Bunce, M.; Casarejos, E.; Cortes, M. L.; Denis Bacelar, A. M.; Deo, A. Y.; Domingo-Pardo, C.; Doncel, M.; Dombradi, Zs.; Engert, T.; Eppinger, K.; Farrelly, G. F.; Farinon, F.; Farnea, E.; Geissel, H.; Gerl, J.; Goel, N.; Gregor, E.; Habermann, T.; Hoischen, R.; Janik, R.; Klupp, S.; Kojouharov, I.; Kurz, N.; Mandal, S.; Menegazzo, R.; Mengoni, D.; Napoli, D. R.; Naqvi, F.; Nociforo, C.; Prochazka, A.; Prokopowicz, W.; Recchia, F.; Ribas, R. V.; Reed, M. W.; Rudolph, D.; Sahin, E.; Schaffner, H.; Sharma, A.; Sitar, B.; Siwal, D.; Steiger, K.; Strmen, P.; Swan, T. P. D.; Szarka, I.; Ur, C. A.; Walker, P. M.; Wollersheim, H.-J.

    2012-09-01

    Neutron-rich isotopes around lead, beyond N = 126, have been studied exploiting the fragmentation of an uranium primary beam at the FRS-RISING setup at GSI. For the first time β-decay half-lives of 219Bi and 211,212,213Tl isotopes have been derived. The half-lives have been extracted using a numerical simulation developed for experiments in high-background conditions. Comparison with state of the art models used in r-process calculations is given, showing a systematic underestimation of the experimental values, at variance from close-lying nuclei.

  2. Shell-model calculations for the semi-magic nucleus 85Br and systematic features of the N = 50 odd-A isotones

    Science.gov (United States)

    Guo, Rui-Ju; Li, Zhi-Quan; Liu, Chen; Tian, Yong-He; Wang, Shou-Yu

    2017-08-01

    Level structures of 85Br have been investigated using the shell-model code nushellx within a large model space containing the neutron-core excitations across the N = 50 closed shell. The calculated results have been compared with the available experimental data. Reasonable agreement between the experimental and calculated values is obtained, which indicates that the neutron-core excitations are essential to reproduce the level structures of 85Br. The systematic features of neutron-core excitations in the N = 50 isotones are investigated. Supported by Natural Science Foundation of China (11622540, 11461141001, U1432119) and Computations were Carried Out on an HP Proliant DL785G6 Server Hosted by the Institute of Space Science of Shandong University

  3. Numerical modeling of incline plate LiBr absorber

    Science.gov (United States)

    Karami, Shahram; Farhanieh, Bijan

    2011-03-01

    Among major components of LiBr-H2O absorption chillers is the absorber, which has a direct effect on the chillier size and whose characteristics have significant effects on the overall efficiency of absorption machines. In this article, heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water-cooled incline plate absorber in the Reynolds number range of 5 lithium bromide aqueous properties to the temperature and concentration is employed as well as dependence of film thickness to vapor absorption. An analysis for linear distribution of wall temperature condition carries out to investigate the reliability of the present numerical method through comparing with previous investigation. The effect of plate angle on heat and mass transfer parameters is investigated and the results show that absorption mass flux and heat and mass transfer coefficient increase as the angle of the plate increase. The main parameters of absorber design, namely Nusselt and Sherwood numbers, are correlated as a function of Reynolds Number and the plate angle.

  4. Nematocid effects of watercress (Nasturtium officinale R. Br.

    Directory of Open Access Journals (Sweden)

    Helena Zahradníková

    2013-01-01

    Full Text Available The watercress (Nasturtium officinale R. Br. is often grown as a forced leaf vegetable rich in vitamins and minerals. Its specific taste and curative effects result from the presence of mustard glycosides (glucosinolates that may also show nematocidic effects. The aim of this study was to evaluate the effect of watercress eluate and juice on tomato plants inoculated with the northern root-knot nematode (NRKN Meloidogyne hapla. It was found out that after the treatment of plants with solutions derived from watercress the yield of fruit was highly significantly increased. The highest yield increase (by 96 % to 165 % was observed in the variant with the highest concentration of watercress extracts (macerate + 200 ml of juice. Although at lower concentrations of watercress solution the increase in yields was also reduced (by 57–118 %, the difference was still statistically highly significant. The effect of this treatment on the content of vitamin C was similar and the increase was also highly significant and ranged from 24 to 67 %. When evaluating the occurrence of nematodes on roots of tomato plants, the presence of pathogens was equal to zero percent in all treated variants. The treatment with this phyto-solution corroborated not only a nematocidic effect of watercress but also its positive influence on the yield and level of vitamin C in dependence on increasing concentrations of the effective agent. It can be therefore concluded that the watercress solution showed a promoting effect on tomato plants.

  5. Systematic hardness measurements on CsClxBr(1–x) and ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Vickers hardness measurements have been made on polycrystalline blanks of CsClxBr(1–x) and single crystals of NH4ClxBr(1–x). The composition dependence of hardness is highly nonlinear in both systems and follows an empirical model that includes a lattice contribution and a disorder contribution.

  6. Diagnostics of low-pressure discharges containing InBr studied for lighting applications

    Science.gov (United States)

    Briefi, S.; Fantz, U.

    2013-10-01

    The utilization of InBr in low-pressure rare-gas plasmas for lighting applications may serve as an efficient alternative to hazardous mercury, which is used in common fluorescent lamps as a radiator. In order to perform systematic investigations of these discharges, diagnostic methods are required to gain insight into the relevant plasma parameters. This goal can be achieved by using white light absorption and optical emission spectroscopy supported by an extended corona model of the indium atom and a simulation of the relative intensity of the InBr emission. The set of diagnostic methods is exemplarily applied to measurements on an inductively coupled argon discharge at 100 W power with varying InBr content. The plasma parameters are derived and the processes determining their changes with varying InBr density are identified. Increasing the InBr density results in a decrease in Te but an increase in ne, which can be explained by considering the ionization and power balance. The relevant population processes for the rovibrational states of InBr are inelastic collisions with heavy particles with an increasing importance of electron impact excitation at a higher InBr density. The radiated power is maximal at a cold spot temperature between 210 and 220 °C as reabsorption occurs at a high InBr density.

  7. LaBr3 gamma?ray spectrometers for space applications

    NARCIS (Netherlands)

    Quarati, F.G.A.

    2013-01-01

    LaBr3 has been developed into large volume scintillator detectors within an ESA and TU Delft programme during this thesis work. The programme, which aimed at the space applications of LaBr3, also led to extensive experiments within a collaborative framework which included representatives for all the

  8. Tuning growth cycles of Brassica crops via natural antisense transcripts of BrFLC.

    Science.gov (United States)

    Li, Xiaorong; Zhang, Shaofeng; Bai, Jinjuan; He, Yuke

    2016-03-01

    Several oilseed and vegetable crops of Brassica are biennials that require a prolonged winter cold for flowering, a process called vernalization. FLOWERING LOCUS C (FLC) is a central repressor of flowering. Here, we report that the overexpression of natural antisense transcripts (NATs) of Brassica rapa FLC (BrFLC) greatly shortens plant growth cycles. In rapid-, medium- and slow-cycling crop types, there are four copies of the BrFLC genes, which show extensive variation in sequences and expression levels. In Bre, a biennial crop type that requires vernalization, five NATs derived from the BrFLC2 locus are rapidly induced under cold conditions, while all four BrFLC genes are gradually down-regulated. The transgenic Bre lines overexpressing a long NAT of BrFLC2 do not require vernalization, resulting in a gradient of shortened growth cycles. Among them, a subset of lines both flower and set seeds as early as Yellow sarson, an annual crop type in which all four BrFLC genes have non-sense mutations and are nonfunctional in flowering repression. Our results demonstrate that the growth cycles of biennial crops of Brassica can be altered by changing the expression levels of BrFLC2 NATs. Thus, BrFLC2 NATs and their transgenic lines are useful for the genetic manipulation of crop growth cycles. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  9. Clumped isotope effects during OH and Cl oxidation of methane

    Science.gov (United States)

    Whitehill, Andrew R.; Joelsson, Lars Magnus T.; Schmidt, Johan A.; Wang, David T.; Johnson, Matthew S.; Ono, Shuhei

    2017-01-01

    A series of experiments were carried out to determine the clumped (13CH3D) methane kinetic isotope effects during oxidation of methane by OH and Cl radicals, the major sink reactions for atmospheric methane. Experiments were performed in a 100 L quartz photochemical reactor, in which OH was produced from the reaction of O(1D) (from O3 photolysis) with H2O, and Cl was from photolysis of Cl2. Samples were taken from the reaction cell and analyzed for methane (12CH4, 12CH3D, 13CH4, 13CH3D) isotopologue ratios using tunable infrared laser direct absorption spectroscopy. Measured kinetic isotope effects for singly substituted species were consistent with previous experimental studies. For doubly substituted methane, 13CH3D, the observed kinetic isotope effects closely follow the product of the kinetic isotope effects for the 13C and deuterium substituted species (i.e., 13,2KIE = 13KIE × 2KIE). The deviation from this relationship is 0.3‰ ± 1.2‰ and 3.5‰ ± 0.7‰ for OH and Cl oxidation, respectively. This is consistent with model calculations performed using quantum chemistry and transition state theory. The OH and Cl reactions enrich the residual methane in the clumped isotopologue in open system reactions. In a closed system, however, this effect is overtaken by the large D/H isotope effect, which causes the residual methane to become anti-clumped relative to the initial methane. Based on these results, we demonstrate that oxidation of methane by OH, the predominant oxidant for tropospheric methane, will only have a minor (∼0.3‰) impact on the clumped isotope signature (Δ13CH3D, measured as a deviation from a stochastic distribution of isotopes) of tropospheric methane. This paper shows that Δ13CH3D will provide constraints on methane source strengths, and predicts that Δ12CH2D2 can provide information on methane sink strengths.

  10. Resonance quadripolaire nucleaire dans les halogenures d'actinides, ThBr 4, ThCl 4 ET UCl 4. II. Polymorphisme et transition de phase du premier ordre dans ThBr 4. Resonance du Brome dans UBr 4.

    Science.gov (United States)

    Gourdji, M.; Péneau, A.; Genet, M.; Guibé, L.

    1983-12-01

    La poursuite de recherches antérieures a permis de caractériser la résonance quadripolaire du brome dans la phase α de ThBr 4 et d'étudier la variation, en fonction de la température, entre 63 et 295 K, de la fréquence de résonance, ν Q(T), correspondante. Une première analyse des conditions expérimentales du passage de la transition α↔β à 426 C a été faite. La résonance du brome dans UBr 4 a également été observée et l'étude en fonction de la température des fréquences de résonance (il y a deux résonances distinctes pour chacun des deux isotopes du brome dans ce composé) a révélé un comportement inattendu en ce sens que les pentes dν Q/dT des courbes ν Q(T) correspondant aux deux résonances sont de signe contraire.

  11. Characterization of soluble bromide measurements and a case study of BrO observations during ARCTAS

    Directory of Open Access Journals (Sweden)

    J. Liao

    2012-02-01

    Full Text Available A focus of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS mission was examination of bromine photochemistry in the spring time high latitude troposphere based on aircraft and satellite measurements of bromine oxide (BrO and related species. The NASA DC-8 aircraft utilized a chemical ionization mass spectrometer (CIMS to measure BrO and a mist chamber (MC to measure soluble bromide. We have determined that the MC detection efficiency to molecular bromine (Br2, hypobromous acid (HOBr, bromine oxide (BrO, and hydrogen bromide (HBr as soluble bromide (Br was 0.9±0.1, 1.06+0.30/−0.35, 0.4±0.1, and 0.95±0.1, respectively. These efficiency factors were used to estimate soluble bromide levels along the DC-8 flight track of 17 April 2008 from photochemical calculations constrained to in situ BrO measured by CIMS. During this flight, the highest levels of soluble bromide and BrO were observed and atmospheric conditions were ideal for the space-borne observation of BrO. The good agreement (R2 = 0.76; slope = 0.95; intercept = −3.4 pmol mol−1 between modeled and observed soluble bromide, when BrO was above detection limit (>2 pmol mol−1 under unpolluted conditions (NO<10 pmol mol−1, indicates that the CIMS BrO measurements were consistent with the MC soluble bromide and that a well characterized MC can be used to derive mixing ratios of some reactive bromine compounds. Tropospheric BrO vertical column densities (BrOVCD derived from CIMS BrO observations compare well with BrOTROPVCD from OMI on 17 April 2008.

  12. Masses of exotic calcium isotopes pin down nuclear forces.

    Science.gov (United States)

    Wienholtz, F; Beck, D; Blaum, K; Borgmann, Ch; Breitenfeldt, M; Cakirli, R B; George, S; Herfurth, F; Holt, J D; Kowalska, M; Kreim, S; Lunney, D; Manea, V; Menéndez, J; Neidherr, D; Rosenbusch, M; Schweikhard, L; Schwenk, A; Simonis, J; Stanja, J; Wolf, R N; Zuber, K

    2013-06-20

    The properties of exotic nuclei on the verge of existence play a fundamental part in our understanding of nuclear interactions. Exceedingly neutron-rich nuclei become sensitive to new aspects of nuclear forces. Calcium, with its doubly magic isotopes (40)Ca and (48)Ca, is an ideal test for nuclear shell evolution, from the valley of stability to the limits of existence. With a closed proton shell, the calcium isotopes mark the frontier for calculations with three-nucleon forces from chiral effective field theory. Whereas predictions for the masses of (51)Ca and (52)Ca have been validated by direct measurements, it is an open question as to how nuclear masses evolve for heavier calcium isotopes. Here we report the mass determination of the exotic calcium isotopes (53)Ca and (54)Ca, using the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at CERN. The measured masses unambiguously establish a prominent shell closure at neutron number N = 32, in excellent agreement with our theoretical calculations. These results increase our understanding of neutron-rich matter and pin down the subtle components of nuclear forces that are at the forefront of theoretical developments constrained by quantum chromodynamics.

  13. Masses of exotic calcium isotopes pin down nuclear forces

    CERN Document Server

    Wienholtz, F; Blaum, K; Borgmann, Ch; Breitenfeldt, M; Cakirli, R B; George, S; Herfurth, F; Holt, J D; Kowalska, M; Kreim, S; Lunney, D; Manea, V; Menéndez, J; Neidherr, D; Rosenbusch, M; Schweikhard, L; Schwenk, A; Simonis, J; Stanja, J; Wolf, R N; Zuber, K

    2013-01-01

    The properties of exotic nuclei on the verge of existence play a fundamental part in our understanding of nuclear interactions. Exceedingly neutron-rich nuclei become sensitive to new aspects of nuclear forces. Calcium, with its doubly magic isotopes $^{40}$Ca and $^{48}$Ca, is an ideal test for nuclear shell evolution, from the valley of stability to the limits of existence. With a closed proton shell, the calcium isotopes mark the frontier for calculations with three-nucleon forces from chiral effective field theory. Whereas predictions for the masses of $^{51}$Ca and $^{52}$Ca have been validated by direct measurements$^4$, it is an open question as to how nuclear masses evolve for heavier calcium isotopes. Here we report the mass determination of the exotic calcium isotopes $^{53}$Ca and $^{54}$Ca, using the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at CERN. The measured masses unambiguously establish a prominent shell closure at neutron number N = 32, in excellent agreement with our t...

  14. X-ray imaging plate using CsBr:Eu phosphors for computed radiography

    Science.gov (United States)

    Nanto, H.; Nishimura, A.; Kuroda, M.; Takei, Y.; Nakano, Y.; Shoji, T.; Yanagita, T.; Kasai, S.

    2007-09-01

    It is shown that X-ray-irradiated Eu-doped CsBr (CsBr:Eu) exhibits intense photostimulated luminescence (PSL). The peak wavelengths of PSL emission and stimulation spectra of CsBr:Eu phosphor ceramic samples are 450 and 690 nm, respectively. The dependence of PSL properties on preparing conditions of phosphor ceramic samples, such as Eu concentration, sintering temperature and sintering time, is studied. It is found that the PSL intensity of CsBr:Eu phosphor ceramics fabricated under optimum preparation condition is higher than that of commercially available imaging plates (IP) using BaFBr:Eu and BaFI:Eu. The image quality of the IP using CsBr:Eu phosphor film is better than that of commercially available IP.

  15. The carcinogenicity of 1-methyl-3(p-bromophenyl)-1-nitrosourea (Br-MPNU).

    Science.gov (United States)

    Warzok, R; Martin, J; Mendel, J; Thust, R; Schwarz, H

    1983-01-01

    In long-term experiments with Hooded rats the carcinogenic potential of 1-methyl-3(p-bromophenyl)-1-nitrosourea (Br-MPNU) could be demonstrated for the first time. Br-MPNU is formed also endogenously after combined administration of 1-methyl-3(p-bromophenyl)-urea (Br-MPU) and sodium nitrite. After repeated intragastric administration of 0.33 mmol Br-MPU and 0.73 mmol NaNO2 per kg b.w. papillomas and carcinomas of the forestomach developed in 83%. After repeated administration of 0.28 mmol Br-MPNU per kg b.w. these neoplasms were observed in 88%. The comparison of results obtained in similar experiments with 1-methyl-3-phenyl-1-nitrosourea shows that bromine substitution led to a reduction of the carcinogenic activity. The present paper is part of a complex program studying the interrelationships between structure, physico-chemical properties, mutagenicity and carcinogenicity of nitrosoureas.

  16. Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events

    Directory of Open Access Journals (Sweden)

    S. C. Lewis

    2010-06-01

    Full Text Available Water isotope records such as speleothems provide extensive evidence of past tropical hydrological changes. During Heinrich events, isotopic changes in monsoon regions have been interpreted as implying a widespread drying through the Northern Hemisphere tropics and an anti-phased precipitation response in the south. Here, we examine the sources of this variability using a water isotope-enabled general circulation model, Goddard Institute for Space Studies ModelE. We incorporate a new suite of vapour source distribution tracers to help constrain the impact of precipitation source region changes on the isotopic composition of precipitation and to identify nonlocal amount effects. We simulate a collapse of the North Atlantic meridional overturning circulation with a large freshwater input to the region as an idealised analogue to iceberg discharge during Heinrich events. An increase in monsoon intensity, defined by vertical wind shear, is modelled over the South American domain, with small decreases simulated over Asia. Simulated isotopic anomalies agree well with proxy climate records, with lighter isotopic values simulated over South America and enriched values across East Asia. For this particular abrupt climate event, we identify which climatic change is most likely linked to water isotope change – changes in local precipitation amount, monsoon intensity, water vapour source distributions or precipitation seasonality. We categorise individual sites according to the climate variability that water isotope changes are most closely associated with, and find that the dominant isotopic controls are not consistent across the tropics – simple local explanations, in particular, fall short of explaining water isotope variability at all sites. Instead, the best interpretations appear to be site specific and often regional in scale.

  17. Development of analytical techniques of vanadium isotope in seawater

    Science.gov (United States)

    Huang, T.; Owens, J. D.; Sarafian, A.; Sen, I. S.; Huang, K. F.; Blusztajn, J.; Nielsen, S.

    2015-12-01

    value of 0‰. The average yield of 96% further shows that our method is not associated with any loss of V. Preliminary results for un-spiked BATS seawater samples reveal V isotopic compositions close to that of the AA standard. Further analyses of BATS seawater as well as the NASS-6 seawater reference material are in progress.

  18. Isotope shifts in francium isotopes Fr-213206 and 221Fr

    Science.gov (United States)

    Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L. A.; Aubin, S.; Gomez, E.; FrPNC Collaboration

    2014-11-01

    We present the isotope shifts of the 7 s1 /2 to 7 p1 /2 transition for francium isotopes 206 -213Fr with reference to 221Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7 s1 /2 to 7 p3 /2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D1 and D2 transitions, of sufficient precision to differentiate between ab initio calculations.

  19. Localisation of gamma-ray interaction points in thick monolithic CeBr3 and LaBr3:Ce scintillators

    Science.gov (United States)

    Ulyanov, Alexei; Morris, Oran; Roberts, Oliver J.; Tobin, Isaac; Hanlon, Lorraine; McBreen, Sheila; Murphy, David; Nelms, Nick; Shortt, Brian

    2017-02-01

    Localisation of gamma-ray interaction points in monolithic scintillator crystals can simplify the design and improve the performance of a future Compton telescope for gamma-ray astronomy. In this paper we compare the position resolution of three monolithic scintillators: a 28×28×20 mm3 (length×breadth × thickness) LaBr3:Ce crystal, a 25×25×20 mm3 CeBr3 crystal and a 25×25×10 mm3 CeBr3 crystal. Each crystal was encapsulated and coupled to an array of 4×4 silicon photomultipliers through an optical window. The measurements were conducted using 81 keV and 356 keV gamma-rays from a collimated 133Ba source. The 3D position reconstruction of interaction points was performed using artificial neural networks trained with experimental data. Although the position resolution was significantly better for the thinner crystal, the 20 mm thick CeBr3 crystal showed an acceptable resolution of about 5.4 mm FWHM for the x and y coordinates, and 7.8 mm FWHM for the z-coordinate (crystal depth) at 356 keV. These values were obtained from the full position scans of the crystal sides. The position resolution of the LaBr3:Ce crystal was found to be considerably worse, presumably due to the highly diffusive optical interface between the crystal and the optical window of the enclosure. The energy resolution (FWHM) measured for 662 keV gamma-rays was 4.0% for LaBr3:Ce and 5.5% for CeBr3. The same crystals equipped with a PMT (Hamamatsu R6322-100) gave an energy resolution of 3.0% and 4.7%, respectively.

  20. Closed suction drain with bulb

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000039.htm Closed suction drain with bulb To use the sharing features on this page, please enable JavaScript. A closed suction drain is used to remove fluids that build ...

  1. BR-SIPP: PETROBRAS Integrated Scheduling System; BR-SIPP: Sistema Integrado de Progamacao de Producao da PETROBRAS

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Cristiane S.; Joly, Marcel; Hassimotto, Marcelo K.; Magalhaes, Marcus Vinicius O. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The lack of a computational aided technology to support short-term scheduling activity in the oil and petrochemical sector has been identified as one of the major obstacles to the harmonic integration of production objectives subsequent to the implementation of the advanced control systems and the consolidation of important benefits at the process unit level. Such technology refers to an analytical tool able to capture plant operational information consistent with the scheduling layer demands, modeling the production system economic performance, and providing mechanisms to consider commercial, operation and technological uncertainties. In this context, PETROBRAS has continuously dedicated effort to develop, implement and enhance its own refinery scheduling solution. Nowadays at its second version, the PETROBRAS Integrated Scheduling System (BR-SIPP - INPI grant 00067400) has become the focus of corporate care, given its critical role on the link between planning objectives and plant operations, according to the hierarchical decision strategy currently adopted by PETROBRAS. This paper presents an overview of the tool and illustrates some real-world applications and main realized benefits. (author)

  2. Theoretical study on the rate constants for the C2H5 + HBr --> C2H6 + Br reaction.

    Science.gov (United States)

    Sheng, Li; Li, Ze-Sheng; Liu, Jing-Yao; Xiao, Jing-Fa; Sun, Chia-Chung

    2004-02-01

    The reaction C(2)H(5) + HBr --> C(2)H(6) + Br has been theoretically studied over the temperature range from 200 to 1400 K. The electronic structure information is calculated at the BHLYP/6-311+G(d,p) and QCISD/6-31+G(d) levels. With the aid of intrinsic reaction coordinate theory, the minimum energy paths (MEPs) are obtained at the both levels, and the energies along the MEP are further refined by performing the single-point calculations at the PMP4(SDTQ)/6-311+G(3df,2p)//BHLYP and QCISD(T)/6-311++G(2df,2pd)//QCISD levels. The calculated ICVT/SCT rate constants are in good agreement with available experimental values, and the calculate results further indicate that the C(2)H(5) + HBr reaction has negative temperature dependence at T 850 K. The current work predicts that the kinetic isotope effect for the title reaction is inverse in the temperature range from 200 to 482 K, i.e., k(HBr)/k(DBr) < 1. Copyright 2003 Wiley Periodicals, Inc.

  3. Alkaline hydrothermal treatment of brominated high impact polystyrene (HIPS-Br) for bromine and bromine-free plastic recovery

    OpenAIRE

    Brebu, Mihai; Bhaskar, Thallada; Muto, Akinori; Sakata, Yusaku

    2006-01-01

    A method to recover both Br and Br-free plastic from brominated flame retardant high impact polystyrene (HIPS-Br) was proposed. HIPS-Br containing 15% Br was treated in autoclave at 280℃ using water or KOH solution of various amounts and concentrations. Hydrothermal treatment (30 ml water) leads to 90% debromination of 1 g HIPS-Br but plastic is strongly degraded and could not be recovered. previous termAlkalinenext term hydrothermal treatment (45 ml or 60 ml KOH 1 M) showed similar debromina...

  4. Abyssnian pea (Lathyrus schaeferi Kosterin pro Pisum abyssinicum A. Br. – a problematic taxon

    Directory of Open Access Journals (Sweden)

    O. E. Kosterin

    2017-12-01

    Full Text Available This is an English translation of a paper published in Russian (but with proper Latin formulations at taxonomical novelties to make them validly published on March 15, 2017 in Vavilov Journal of Genetics and Plant Breeding, Vol. 22 (2: 158-169. The Abyssinian pea (Pisum abyssinicum A. Br., concerned in this review, is known from Ethiopia and Yemen, where it is cultivated along with the common pea (Pisum sativum L. subsp. sativum. The continuously reproduced notion of its possible spontaneous occurrence in the wild ascends to suppositions made in the XIX century and is not based on any actual data. P. abyssinicum is of practical interest owing to its extra early ripening and resistance to bacterial blight. Morphologically it is very similar to P. sativum but its crossability with it is bad as either seed or pollen parent. Traditionally this reproductive barrier was associated with karyological differences. The Abyssinian pea karyotype is variable as 1–2 reciprocal translocations were reported. At the same time there are accessions not differing from the standard karyotype of P. sativum with respect to reciprocal translocations, yet their crossability with the latter is very low and the pollen fertility of F1 and F2 hybrids is lowered. Data were reported on influence of the region of Linkage Group III, containing a gene known to participate in the conflict of nucleus and plastids in remote crosses of peas, on the pollen fertility of hybrids with abyssinian pea. With their karyological variability, the known accessions of the Abyssinian pea are very close to each other genetically, as they diverged just about 4 000 years ago. The presence of alleles of molecular markers common with Pisum fulvum Sibth. et Smith on the one hand and with P. sativum L. subsp. elatius (Bieb. Schmalh. on the other hand evidences in favour of an old hypotheses by L.I. Govorov that the Abyssinian pea originated from their spontaneous hybrid. This spontaneous cross may

  5. Airborne Measurements of BrO and the Sum of HOBr and Br2 over the Tropical West Pacific from 1 to 15 Km During the CONvective TRansport of Active Species in the Tropics (CONTRAST) Experiment

    Science.gov (United States)

    Chen, Dexian; Huey, L. Gregory; Tanner, David J.; Salawitch, Ross J.; Anderson, Daniel C.; Wales, Pamela A.; Pan, Laura L.; Atlas, Elliot L.; Hornbrook, Rebecca S.; Apel, Eric C.; hide

    2016-01-01

    A chemical ionization mass spectrometer was used to measure BrO and HOBr + Br2 over the Tropical West Pacific Ocean within the altitude range of 1 to 15 km, during the CONvective TRansport of Active Species in the Tropics (CONTRAST) campaign in 2014. Isolated episodes of elevated BrO (up to 6.6 pptv) and/or HOBr + Br2 (up to 7.3 pptv) were observed in the tropical free troposphere (TFT) and were associated with biomass burning. However, most of the time we did not observe significant BrO or HOBr + Br2 in the TFT and the tropical tropopause layer (TTL) above our limits of detection (LOD). The 1 min average LOD for BrO ranged from 0.6 to 1.6 pptv and for HOBr + Br2 ranged from 1.3 to 3.5 pptv. During one flight, BrO observations from the TTL to the extratropical lowermost stratosphere were used to infer a profile of inorganic bromine (Br(sub y)). Based on this profile, we estimated the product gas injection of bromine species into the stratosphere to be 2 pptv. Analysis of Br(sub y) partitioning further indicates that BrO levels are likely very low in the TFT environment and that future studies should target the measurement of HBr or atomic Br.

  6. A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis

    Directory of Open Access Journals (Sweden)

    Mariano Goldberg

    2016-08-01

    Full Text Available Starting from (S-β-phenylalanine, easily accessible by lipase-catalyzed kinetic resolution, a chiral triamine was assembled by a reductive amination and finally cyclized to form the title compound 10. In the crystals of the guanidinium benzoate salt the six membered rings of 10 adopt conformations close to an envelope with the phenyl substituents in pseudo-axial positions. The unprotonated guanidine 10 catalyzes Diels–Alder reactions of anthrones and maleimides (25–30% ee. It also promotes as a strong Brønsted base the retro-aldol reaction of some cycloadducts with kinetic resolution of the enantiomers. In three cases, the retro-aldol products (48–83% ee could be recrystallized to high enantiopurity (≥95% ee. The absolute configuration of several compounds is supported by anomalous X-ray diffraction and by chemical correlation.

  7. Isotopes a very short introduction

    CERN Document Server

    Ellam, Rob

    2016-01-01

    An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable while others are radioactive, and some may only exist fleetingly before decaying into other elements. In this Very Short Introduction, Rob Ellam explains how isotopes have proved enormously important across all the sciences and in archaeology. Radioactive isotopes may be familiar from their use in nuclear weapons, nuclear power, and in medicine, as well as in carbon dating. They have been central to establishing the age of the Earth and the origins of the solar system. Combining previous and new research, Ellam provides an overview of the nature of stable and radioactive isotopes, and considers their wide range of modern applications. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subjec...

  8. Close to the Sky

    Science.gov (United States)

    2007-11-01

    Today, a new ALMA outreach and educational book was publicly presented to city officials of San Pedro de Atacama in Chile, as part of the celebrations of the anniversary of the Andean village. ESO PR Photo 50a/07 ESO PR Photo 50a/07 A Useful Tool for Schools Entitled "Close to the sky: Biological heritage in the ALMA area", and edited in English and Spanish by ESO in Chile, the book collects unique on-site observations of the flora and fauna of the ALMA region performed by experts commissioned to investigate it and to provide key initiatives to protect it. "I thank the ALMA project for providing us a book that will surely be a good support for the education of children and youngsters of San Pedro de Atacama. Thanks to this publication, we expect our rich flora and fauna to be better known. I invite teachers and students to take advantage of this educational resource, which will be available in our schools", commented Ms. Sandra Berna, the Mayor of San Pedro de Atacama, who was given the book by representatives of the ALMA global collaboration project. Copies of the book 'Close to the sky' will be donated to all schools in the area, as a contribution to the education of students and young people in northern Chile. "From the very beginning of the project, ALMA construction has had a firm commitment to environment and local culture, protecting unique flora and fauna species and preserving old estancias belonging to the Likan Antai culture," said Jacques Lassalle, who represented ALMA at the hand-over. "Animals like the llama, the fox or the condor do not only live in the region where ALMA is now being built, but they are also key elements of the ancient Andean constellations. In this sense they are part of the same sky that will be explored by ALMA in the near future." ESO PR Photo 50c/07 ESO PR Photo 50c/07 Presentation of the ALMA book The ALMA Project is a giant, international observatory currently under construction on the high-altitude Chajnantor site in Chile

  9. Speciation and Sources of Brown Carbon in Precipitation at Seoul, Korea: Insights from Excitation-Emission Matrix Spectroscopy and Carbon Isotopic Analysis.

    Science.gov (United States)

    Yan, Ge; Kim, Guebuem

    2017-10-17

    Brown carbon (BrC) plays a significant role in the Earth's radiative balance, yet its sources and chemical composition remain poorly understood. In this work, we investigated BrC in the atmospheric environment of Seoul by characterizing dissolved organic matter in precipitation using excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). The two independent fluorescent components identified by PARAFAC were attributed to humic-like substance (HULIS) and biologically derived material based on their significant correlations with measured HULIS isolated using solid-phase extraction and total hydrolyzable tyrosine. The year-long observation shows that HULIS contributes to 66 ± 13% of total fluorescence intensity of our samples on average. By using dual carbon ( 13 C and 14 C) isotopic analysis conducted on isolated HULIS, the HULIS fraction of BrC was found to be primarily derived from biomass burning and emission of terrestrial biogenic gases and particles (>70%), with minor contributions from fossil-fuel combustion. The knowledge derived from this study could contribute to the establishment of a characterizing system of BrC components identified by EEM spectroscopy. Our work demonstrates that, EEM fluorescence spectroscopy is a powerful tool in BrC study, on the basis of its chromophore resolving power, allowing investigation into individual components of BrC by other organic matter characterization techniques.

  10. Germanium Isotopic Fractionation in Iron Meteorites : Comparison with Experimental Data

    Science.gov (United States)

    Luais, B.; Toplis, M.; Tissandier, L.; Roskosz, M.

    2009-05-01

    t, values being isotopically lighter than the reference Ge standard after 2 hours (δ74Ge ˜ - 0.5 ‰), reaching a δ 74Ge of ˜ +3‰ after 60 hours. For a series of experiments running for 24 hours, an increase in δ74Ge (from ˜ -0.3 to +10‰) is observed with increasing fO2. The slight enrichment of light isotopes in the metallic phase at very low fO2 and short t could reflect the consequence of Ge diffusion from the silicate to the metal. This small extent of fractionation can be compared with the nearly constant δ74Ge values in magmatic Fe-meteorites, indicating that diffusion-induced metal-silicate segregation would produce very small if detectable isotopic fractionation. Therefore, Ge isotopic composition of Fe-meteorites would be close to that of their parent bodies. On the other hand, strong enrichment in heavy isotopes at high fO2 and/or long t is indicative of Ge loss by evaporation, and would explain the large isotopic fractionation toward heavy δ 74Ge values for the IIE non-magmatic irons, interpreted as impact-induced evaporation of Ge. [1] Luais B (2007) EPSL 262 p. 21

  11. Vertebrados silvestres atropelados na BR 158, RS, Brasil

    Directory of Open Access Journals (Sweden)

    Daniela da Silva Oliveira

    2012-09-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2012v25n4p229   Entre os problemas que ameaçam a fauna silvestre, o atropelamento de animais é uma importante causa de mortalidade para várias espécies. O presente estudo visou identificar as espécies vitimadas por atropelamento em 98km da rodovia BR 158, entre o município de Cruz Alta e o distrito de Val de Serra, município de Júlio de Castilhos, RS e analisar as variações mensais nas taxas de atropelamento e sua correlação com o volume mensal de chuvas. Foram realizadas expedições mensais, entre os meses de abril a setembro de 2007, onde se registrou 61 animais atropelados pertencentes a 15 espécies, com uma taxa de atropelamento de 0,10 ind./km/mês. As espécies com maior número de atropelamentos foram o zorrilho (Conepatus chinga, com 17 indivíduos (28%, seguida pelo graxaim-do-campo (Lycalopex gymnocercus, com sete (11% e o graxaim-do-mato (Cerdocyon thous, com cinco (8%. Não foi encontrada diferença nas taxas de atropelamento entre os meses amostrados, contudo, o mês com maior registro de atropelamentos foi setembro (n=18. Também não foi verificada correlação entre os atropelamentos e a precipitação mensal, no entanto, há uma tendência entre a ocorrência dos atropelamentos com um volume maior de chuvas.

  12. Integrated hydrogeochemical, isotopic and geomorphological depiction of the groundwater salinization in the aquifer system of Delhi, India

    Science.gov (United States)

    Kumar, Manish; Rao, M. Someshwar; Deka, Jyoti Prakash; Ramanathan, AL.; Kumar, Bhishm

    2015-11-01

    The problem of salinization in the Delhi aquifer, that currently exhibits rapid landuse change, is conspicuous and severe. Salinization may be caused either by a single process, or a combination of different processes; including anthropogenic related activities, water logging and evaporative concentration of salts, influx of natural saline water, upconing of brines from the deeper parts of the aquifer, and airborne salts depositions. However, there is a lack of well-proven theory that can explain the salinity of the order of 5000 μS/cm in the deeper aquifers of Delhi. This work identifies inconclusiveness in the previous theories of marine ingression, evaporation enrichment and subsequent leaching of salt. Further, the study depicts a conceptual understanding of the origin of salinity in groundwater based on the integrated investigations of groundwater quality, age and stable isotopic fingerprinting as well as GIS based mapping of geomorphic features. In order to explain the salinity observed in groundwater of NCT Delhi, a phenomenological scenario is illustrated and supported by additional evidences. The highest average EC value was for the shallow aquifer and is strongly symptomatic of anthropogenic influences on groundwater chemistry. Piper diagram showed heterogeneous water type and sufficient recharge/mixing of the groundwater from different aquifers. The relationship between Cl-/Br- ratios vs. Cl- indicated dissolution of salt deposits containing evaporative fraction present in the unsaturated zones or in the sediments of deeper aquifers and leaching of evaporative minerals from dunes of the adjacent Thar Desert. Cl-/SO42- ratio suggested the presence of connate seawater, halite dissolution and concentration of dissolved salts by evapo-transpiration of river water diverted for irrigation. The results show, that the closed inland marine conditions developed and buried with the active sedimentation in the geological past in this region, and further intensive

  13. Surface area dependence of calcium isotopic reequilibration in carbonates: Implications for isotopic signatures in the weathering zone

    Science.gov (United States)

    Fernandez, N. M.; Druhan, J. L.; Potrel, A.; Jacobson, A. D.

    2016-12-01

    The concept of dynamic equilibrium carries the implicit assumption of continued isotopic exchange between a mineral and the surrounding fluid. While this effect has received much attention in the marine paleoproxy literature, it has been relatively overlooked in application to the terrestrial environment. In weathering systems, a potential consequence is that rapid reequilibration may alter or erase isotopic signatures generated during secondary mineral formation. The extent and timescale over which isotopic signatures are reset in these hydrologic systems is unknown. Using reactive transport modeling, we show isotopic reequilibration under conditions reflecting terrestrial hydrologic settings to be significant and dependent on the reactive surface area of the solid. In particular, we suggest that the non-traditional stable isotopes commonly used in application to carbonates (e.g., Ca, Mg, Sr) are sensitive to these effects due to their rapid reaction rates. We aim to characterize the dependence of Ca isotopic reequilibration on surface area during calcite precipitation via batch experiments conducted at ambient temperature over 48-hour time periods. Calcite precipitation was performed in a closed batch reactor utilizing a controlled free-drift method. The batch reactors contained mixed supersaturated solutions of CaCl2 and NaHCO3 at an initial pH of 8.54. Precipitation was initiated by seed inoculation of calcite crystals with two distinct, pre-constrained surface areas. All experiments achieved the same final state of chemical equilibrium, but as expected, the fastest approach to equilibrium occurred for experiments employing calcite seeds with the highest surface area. This implies that differences in equilibrated Ca isotope ratios (δ44/40Ca) should reflect differences in surface area. This prediction is upheld by models of the experiments, indicating a measureable difference in δ44Ca during calcite precipitation where the higher surface area corresponds to

  14. Satellite observations of long range transport of a large BrO plume in the Arctic

    Directory of Open Access Journals (Sweden)

    M. Begoin

    2010-07-01

    Full Text Available Ozone Depletion Events (ODE during polar springtime are a well known phenomenon in the Arctic and Antarctic boundary layer. They are caused by the catalytic destruction of ozone by halogens producing reactive halogen oxides like bromine monoxide (BrO. The key halogen bromine can be rapidly transferred into the gas phase in an autocatalytic process – the so called "Bromine Explosion". However, the exact mechanism, which leads to an initial bromine release as well as the influence of transport and chemical processes on BrO, is still not clearly understood. <br>> In this study, BrO measurements from the satellite instrument GOME-2 are used together with model calculations with the dispersion model FLEXPART to study an arctic BrO event in March 2007, which could be tracked over several days and a large area. Full BrO activation was observed within one day east of Siberia with subsequent transport to Hudson Bay. The event was linked to a cyclone with very high surface wind speeds, which could have been involved in the production and lifting of aerosols or blowing snow. Considering the short life time of BrO, transported aerosols or snow can also provide the surface for BrO recycling within the plume for several days. The evolution of the BrO plume could be reproduced by FLEXPART simulations of a passive tracer indicating that the activated air mass was transported all the way from Siberia to Hudson Bay. To localise the most probable transport height, model runs initialised in different heights have been performed showing similar transport patterns throughout the troposphere but best agreement with the measurements between the surface and 3 km. The influence of changes in tropopause height on measured BrO values has been considered, but cannot completely explain the observed high BrO values. Backward trajectories from the area of BrO initialisation show upward lifting from the surface up to 3 km and no indication for intrusion of stratospheric

  15. Neutron-rich polonium isotopes studied with in-source laser spectroscopy

    CERN Document Server

    Dexters, Wim; Cocolios, T E

    This work studies the unknown region of neutron rich polonium isotopes. The polonium isotopes, with Z=84, lie above the magic lead nuclei (Z=82). The motivation for this research can mainly be found in these lead nuclei. When looking at the changes in the mean square charge radii beyond the N=126 shell gap, a kink is observed. This kink is also found in the radon (Z=86) and radium (Z=88) isotopes. The observed effect cannot be reproduced with our current models. The polonium isotopes yield more information on the kink and they are also able to link the known charge radii in lead isotopes to those in radon and radium. Additionally, the nuclear moments of the odd-neutron isotope $^{211}$Po are investigated. This nucleus has two protons and one neutron more than the doubly magic nucleus $^{208}$Pb. Nuclear moments of isotopes close to this doubly magic nucleus are good tests for the theoretic models. Besides pushing the models to their limits, the nuclear moments of $^{211}$Po also yield new information on the f...

  16. Sulphur and carbon isotopic composition of power supply coals in the Pannonian Basin, Hungary

    Energy Technology Data Exchange (ETDEWEB)

    Hamor-Vido, Maria [Eoetvoes Lorand Geophysical Institute of Hungary, H-1145 Budapest, Kolumbusz st. 17-23 (Hungary); Hamor, Tamas [Hungarian Geological Survey, H-1143 Budapest, Stefania st. 14 (Hungary)

    2007-08-01

    The present work is an attempt to establish the stable isotope database for Mesozoic to Tertiary coals from the Pannonian Basin, Hungary. Maceral composition, proximate analysis, sulphur form, sulphur isotopes (organic and pyritic), and carbon isotopes were determined. This database supports the assessment of the environmental risks associated with energy generation, the characterization of the formation and the distribution of sulphur in the coals used. The maceral composition, the sulphur composition, the C, S isotopic signatures, and some of the geological evidences published earlier show that the majority of these coals were deposited in freshwater and brackish water environments, despite the relatively high average sulphur content. However, the Upper Cretaceous, Eocene, and Lower Miocene formations also contain coal seams of marine origin, as indicated by their maceral composition and sulphur and carbon chemistry. The majority of the sulphur in these coals occurs in the organic form. All studied sulphur phases are relatively rich in {sup 34}S isotopes ({delta}{sup 34}S{sub organic} = + 12.74 permille, {delta}{sup 34}S{sub pyrite} = + 10.06 permille, on average). This indicates that marine bacterial sulphate reduction played a minor role in their formation, in the sense that isotopic fractionation was limited. It seems that the interstitial spaces of the peat closed rapidly during early diagenesis due to a regime of high depositional rate, leading to a relative enrichment of the heavy sulphur isotopes. (author)

  17. Study of polonium isotopes ground state properties by simultaneous atomic- and nuclear-spectroscopy

    CERN Multimedia

    Koester, U H; Kalaninova, Z; Imai, N

    2007-01-01

    We propose to systematically study the ground state properties of neutron deficient $^{192-200}$Po isotopes by means of in-source laser spectroscopy using the ISOLDE laser ion source coupled with nuclear spectroscopy at the detection setup as successfully done before by this collaboration with neutron deficient lead isotopes. The study of the change in mean square charge radii along the polonium isotope chain will give an insight into shape coexistence above the mid-shell N = 104 and above the closed shell Z = 82. The hyperfine structure of the odd isotopes will also allow determination of the nuclear spin and the magnetic moment of the ground state and of any identifiable isomer state. For this study, a standard UC$_{x}$ target with the ISOLDE RILIS is required for 38 shifts.

  18. Experimental determination of isotope enrichment factors – bias from mass removal by repetitive sampling

    DEFF Research Database (Denmark)

    Buchner, Daniel; Jin, Biao; Ebert, Karin

    2017-01-01

    Application of compound-specific stable isotope approaches often involves comparisons of isotope enrichment factors (ε). Experimental determination of ε-values is based on the Rayleigh equation, which relates the change in measured isotope ratios to the decreasing substrate fractions and is valid...... for closed systems. Even in well-controlled batch experiments, however, this requirement is not necessarily fulfilled, since repetitive sampling can remove a significant fraction of the analyte. For volatile compounds the need for appropriate corrections is most evident and various methods have been proposed....... Application of inappropriate methods may lead to incorrect and inconsistent ε-values entailing misinterpretations regarding the processes underlying isotope fractionation. In fact, our results suggest that artifacts arising from inappropriate data evaluation might contribute to the variability of published ε...

  19. Energetics and control of ultracold isotope-exchange reactions between heteronuclear dimers in external fields

    Science.gov (United States)

    Tomza, Michal

    2017-04-01

    We show that isotope-exchange reactions between ground-state alkali-metal, alkaline-earth-metal, and lanthanide heteronuclear dimers consisting of two isotopes of the same atom are exothermic with an energy change in the range of 1-8000 MHz, thus resulting in cold or ultracold products. For these chemical reactions, there are only one rovibrational and at most several hyperfine possible product states. The number and energetics of open and closed reactive channels can be controlled by the laser and magnetic fields. We suggest a laser-induced isotope- and state-selective Stark shift control to tune the exothermic isotope-exchange reactions to become endothermic, thus providing the ground for testing models of the chemical reactivity. The present proposal opens the way for studying the state-to-state dynamics of ultracold chemical reactions beyond the universal limit with a meaningful control over the quantum states of both reactants and products.

  20. Non-linear Isotope Effects

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht

    The isotopic fractionation associated with photodissociation of N2O, OCS and CO2, at different altitudes in Earth’s atmosphere, is investigated theoretically using constructed quantum mechanical models of the dissociation processes (i.e. potential energy surfaces and relevant coupling elements......’s stratosphere is nearly mass dependent, and only a small fraction of the observed anomalous oxygen-17 excess can be attributed to N2O photolysis. In contrast, stratospheric photolysis produces a significant inverse clumped isotope effect.(ii) Stratospheric OCS photolysis significantly enrich the remaining OCS...... in heavy carbon. The sulfur fractionation is weak and photolysis of OCS in the stratosphere produces only a small and mass dependent enrichment of heavy sulfur isotopes in the remaining OCS. Sulfur fractionation from the two remaining chemical sinks (oxidation by O(3P) and OH, respectively) is weak...

  1. Isotope specific arbitrary material sorter

    Science.gov (United States)

    Barty, Christopher P.J.

    2015-12-08

    A laser-based mono-energetic gamma-ray source is used to provide a rapid and unique, isotope specific method for sorting materials. The objects to be sorted are passed on a conveyor in front of a MEGa-ray beam which has been tuned to the nuclear resonance fluorescence transition of the desired material. As the material containing the desired isotope traverses the beam, a reduction in the transmitted MEGa-ray beam occurs. Alternately, the laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.

  2. Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites.

    Science.gov (United States)

    Cao, Weiwei; Zhang, Yu; Wang, Xi; Chen, Yinyan; Li, Qiang; Xing, Xiaodong; Xiao, Yuhong; Peng, Xuefeng; Ye, Zhiwen

    2017-07-01

    Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag+ ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag+ ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag+ ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

  3. Geografia do trabalho no Brasil Géographie du travail au Brésil

    Directory of Open Access Journals (Sweden)

    Alexandre Gori Maia

    2009-06-01

    ídos do país. A área mais contígua de municípios mais desenvolvidos ocorre próxima aos dois principais estados brasileiros, São Paulo e Rio de Janeiro, além de importantes bolsões de desenvolvimento próximos à faixa litorânea. Os municípios rurais menos desenvolvidos, por sua vez, predominam nas áreas do semi-áridas do país, na floresta amazônica e na tríplice fronteira com os países do Mercosul.L'article traite de la configuration territoriale du travail au Brésil par l'analyse des structures d'activité et des rémunérations à l'échelle des municipes: la combinaison entre les catégories socio-professionnelles et les classes de salaire informe sur les niveaux de développement socio-économique des municipes et sur les inégalités du territoire brésilien. La profession est plus ou moins favorable en termes de revenus, mais elle a aussi des conséquences en termes de prestige social et de pouvoir politique. Compte tenu de l'extrême inégalité des salaires au Brésil, même dans des catégories professionnelles relativement homogènes, l'article prend le montant de salaire de l'activité principale comme second critère de classification. L'analyse statistique multivariée à partir des informations du recensement démographique de 2000 donne matière à une carte qui donne à voir une hiérarchie socio-économique des municipes brésiliens. La plupart des municipes pauvres  présentent des activités agricoles dominantes et  comptent beaucoup de travailleurs à bas salaire. Les municipes urbains les plus développés  concentrent une bonne partie de la population brésilienne et comptent à la fois beaucoup de personnes dans les strates de revenus élevées et beaucoup d'exclus. Les zones contiguës à ces municipes se trouvent à proximité des Etats de Sao Paulo et de Rio de Janeiro, ainsi que près du littoral. Les municipes ruraux les moins développés se trouvent, eux, dans la zone semi-aride, dans la forêt amazonienne et près de la

  4. Electromigration in molten salts and application to isotopic separation of alkaline and alkaline-earth elements; Electromigration en sels fondus et application a la separation des isotopes des elements alcalins et alcalino-terreux

    Energy Technology Data Exchange (ETDEWEB)

    Menes, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The separation of the isotopes of the alkaline-earth elements has been studied using counter-current electromigration in molten bromides. The conditions under which the cathode operates as a bromine electrode for the highest possible currents have been examined. For the separation of calcium, it has been necessary to use a stable CaBr{sub 2} - (CaBr{sub 2} + KBr) 'chain'. In the case of barium and strontium, it was possible to employ the pure bromides. Enrichment factors of the order of 10 for {sup 48}Ca and of the order of 1.5 for the rare isotopes of barium and strontium have been obtained. In the case of magnesium the method is slightly more difficult to apply because of material loss due to the relatively high vapour pressure of the salt requiring the use of electrolyte chains, MgBr{sub 2} - CeBr{sub 3}. A study has been made that has led to a larger-scale application of the method. These are essentially the inhibition of reversible operation of the cathode by traces of water, limiting the intensity which can be tolerated; evacuation of the heat produced by the Joule effect, in the absence of which the separation efficiency is reduced by thermal gradients; corrosion of the materials by molten salts at high temperature. Several cells capable of treating a few kilograms of substance have been put into operation; none of these has lasted long enough to produce a satisfactory enrichment. The method is thus limited actually to yields of the order of a few grams. (author) [French] On a etudie la separation des isotopes des elements alcalino-terreux par electromigration a contre-courant en bromures fondus. On a etudie les conditions dans lesquelles la cathode fonctionne en electrode a brome pour des intensites les plus elevees possibles. Pour la separation du calcium, il a ete necessaire d'utiliser une chaine stable CaBr{sub 2} - (CaBr{sub 2} + KBr). Pour le baryum et le strontium, on a pu operer sur les bromures purs. On a obtenu des facteurs d

  5. Dependence of the four-atom reaction HBr + OH → Br + H2O on temperatures between 20 and 2000 K.

    Science.gov (United States)

    Ree, J; Kim, Y H; Shin, H K

    2015-04-02

    A quasiclassical trajectory method is used to study the temperature dependence of HBr + OH → Br + H2O using analytic forms of two-, three-, and four-body and long-range interaction potentials. Below 300 K, the reaction is attraction-driven and occurs through formation of a collision complex BrH···OH, which is sufficiently long-lived to enhance H atom tunneling. Strong negative temperature dependence of the complex-mode rate is found between 20 and 300 K, consistent with experimental data reported by various authors. Above 300 K, the reaction occurs primarily through a direct-reaction mechanism. The sum of the complex- and direct-mode rates is shown to describe the reaction over the wide range 20-2000 K. The primary kinetic isotope effect is nearly constant with the normal H reaction faster by a factor of ∼1.7 over the entire temperature range. The product energy distribution in vibration, rotation, and translation at 300 K is found to be 48, 8, and 44%, respectively. The 1:1 resonance leads to efficient flow of energy between the stretching modes. Less than a quarter of the H2O vibrational energy deposits in the bending mode through intramolecular flow from the two stretching modes.

  6. Cosmology: Rare isotopic insight into the Universe

    Science.gov (United States)

    Prantzos, Nikos

    2016-01-01

    Light isotopes of hydrogen and helium formed minutes after the Big Bang. The study of one of these primordial isotopes, helium-3, has now been proposed as a useful strategy for constraining the physics of the standard cosmological model.

  7. AgBr-Coupled TiO2: A Visible Heterostructured Photocatalyst for Degrading Dye Pollutants

    Directory of Open Access Journals (Sweden)

    Jianjun Liu

    2012-01-01

    Full Text Available A series of AgBr/TiO2 visible photocatalysts with heterojunction structure was synthesized using Ti(OC4H94, KBr, and AgNO3 as precursors. The phase composition, particle morphology and size, microstructures, and absorbance of these photocatalysts were characterized by X-ray diffraction, transmission electron microscope (TEM, high-resolution TEM, and UV-vis spectra. It was found that the coupled AgBr/TiO2 was an effective photocatalyst to degrade the methylene blue under visible light irradiation, compared with the other noncoupled photocatalysts of AgBr, AgBr/P25, and P25. The photocatalytic activities of AgBr/TiO2 increase first and then decrease with increasing the mass ratio of mAgNO3/mTiO2 and the photocatalyst with the mass ratio of 3.35 has the highest photocatalytic activity. The results showed that the coupled photocatalyst has the particle size of about 15 nm with homogeneous dispersion and has the strongest absorption in whole UV-vis light region (250∼800 nm originated from the synergetic effect of heterostructured AgBr/TiO2. The coupled AgBr/TiO2 photocatalyst can keep stable photocatalytic activity after five-circle runs.

  8. Novel x-ray image sensor using CsBr:Eu phosphor for computed radiography

    Science.gov (United States)

    Nanto, H.; Takei, Y.; Nishimura, A.; Nakano, Y.; Shouji, T.; Yanagita, T.; Kasai, S.

    2006-03-01

    CsBr phosphor ceramics doped with different luminescence center such as In IIO 3, Eu IIO 3, EuCl 3, SmCl 3, TbCl 3, GdCl 3 or NdCl 3 as a candidate of a new photosimulable phosphor for medical x-ray imaging sensor are prepared using a conventional ceramic fabrication process. It is found that x-ray-irradiated Eu-doped CsBr (CsBr:Eu) exhibits intense photostimulated luminescence (PSL). The peak wavelength of the PSL emission and stimulation spectra of CsBr:Eu phosphor ceramic sample is 450 nm and 690 nm, respectively. The dependence of PSL properties on preparing conditions of phosphor ceramic samples, such as Eu concentration, sintering temperature and sintering time, is studied and the optimum preparing condition is also studied. It is found that the PSL intensity of CsBr:Eu phosphor ceramics fabricated under optimum preparation condition is higher than that of commercially available imaging plate (IP) using BafBr:Eu. The image quality of the IP using CsBr:Eu phosphor film is better than that of commercially available IP.

  9. Pure Cs4PbBr6: Highly Luminescent Zero-Dimensional Perovskite Solids

    KAUST Repository

    Saidaminov, Makhsud I.

    2016-09-26

    So-called zero-dimensional perovskites, such as Cs4PbBr6, promise outstanding emissive properties. However, Cs4PbBr6 is mostly prepared by melting of precursors that usually leads to a coformation of undesired phases. Here, we report a simple low-temperature solution-processed synthesis of pure Cs4PbBr6 with remarkable emission properties. We found that pure Cs4PbBr6 in solid form exhibits a 45% photoluminescence quantum yield (PLQY), in contrast to its three-dimensional counterpart, CsPbBr3, which exhibits more than 2 orders of magnitude lower PLQY. Such a PLQY of Cs4PbBr6 is significantly higher than that of other solid forms of lower-dimensional metal halide perovskite derivatives and perovskite nanocrystals. We attribute this dramatic increase in PL to the high exciton binding energy, which we estimate to be ∼353 meV, likely induced by the unique Bergerhoff–Schmitz–Dumont-type crystal structure of Cs4PbBr6, in which metal-halide-comprised octahedra are spatially confined. Our findings bring this class of perovskite derivatives to the forefront of color-converting and light-emitting applications.

  10. Thinning CsPb2Br5 perovskite down to monolayers: Cs-dependent stability

    Science.gov (United States)

    Iyikanat, F.; Sari, E.; Sahin, H.

    2017-10-01

    Using first-principles density functional theory calculations, we systematically investigate the structural, electronic, and vibrational properties of bulk and potential single-layer structures of perovskitelike CsPb2Br5 crystal. It is found that while Cs atoms have no effect on the electronic structure, their presence is essential for the formation of stable CsPb2Br5 crystals. The calculated vibrational spectra of the crystal reveal that not only the bulk form but also the single-layer forms of CsPb2Br5 are dynamically stable. Predicted single-layer forms can exhibit either semiconducting or metallic character. Moreover, the modification of the structural, electronic, and magnetic properties of single-layer CsPb2Br5 upon formation of vacancy defects is investigated. It is found that the formation of Br vacancy (i) has the lowest formation energy, (ii) significantly changes the electronic structure, and (iii) leads to ferromagnetic ground state in the single-layer CsPb2Br5 . However, the formation of Pb and Cs vacancies leads to p -type doping of the single-layer structure. Results reported herein reveal that the single-layer CsPb2Br5 crystal is a novel stable perovskite with enhanced functionality and a promising candidate for nanodevice applications.

  11. Studies on Ca2+-Doped CeBr3 Scintillating Materials

    Energy Technology Data Exchange (ETDEWEB)

    Guss, P. [NSTec; Foster, M. E. [SNL; Wong, B. M. [SNL; Doty, F. P. [SNL; Shah, K. [RMD; Squillante, M. [RMD; Glodo, J. [RMD; Yuan, D. [NSTec

    2013-07-03

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide (LaBr3:Ce), their commercial availability and application is limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. The objective of this investigation was to employ aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was investigated as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using the density functional theory within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  12. Isotopic depletion of soluble boron in a PWR

    Energy Technology Data Exchange (ETDEWEB)

    Aragones, J.M.; Ahnert, C.; Crespo, A.; Leon, J.R.

    1988-01-01

    The purpose of the work reported in this paper is to determine the isotopic depletion of the soluble boron in the primary of a pressurized water reactor (PWR) along cycle operation under the limiting condition of continuous boron dilution without fresh boron feeding, which maximizes the boron isotopic depletion effect. Presented here are the results for cycle 4 of the C.N. Almaraz-II PWR, which has been operated close to these continuous dilution conditions at rated power throughout most of the cycle. The limiting continuous boron dilution model with the /sup 10/B depletion calculations based on the COBAYA code is in quite good agreement with the measured boron concentrations for this cycle, explaining very well the differences found with the expected design letdown curve, which increased up to +60 ppm at middle of cycle when this work was done.

  13. Strontium, boron, oxygen, and hydrogen isotope geochemistry of brines from basal strata of the Gulf Coast sedimentary basin, USA

    Science.gov (United States)

    Moldovanyi, Eva P.; Walter, Lynn M.; Land, Lynton S.

    1993-05-01

    Significant spatial heterogeneities exist in the stable isotopic composition of saline formation waters from reservoirs of the Smackover Formation (Upper Jurassic). We focused on the southwest Arkansas shelf, a structurally simple portion of one of the interior basins of the northern Gulf Coast sedimentary basin. Here, faulting and facies changes juxtapose dominantly oolitic carbonate strata against basal evaporites, red beds, and siliciclastics, as well as metamorphosed basement rocks. Brines from this area have exceptionally high Br and alkali element concentrations and have spatially heterogeneous hydrogen sulfide concentrations. Strontium, boron, oxygen, and hydrogen isotope compositions exhibit coherent relations with other aspects of brine geochemistry. Sr isotope compositions range from those expected for carbonates and evaporites deposited from Jurassic seawater (0.7071) to radiogenic ratios as high as 0.7107. Generally, most radiogenic Sr isotope values are associated with H 2S-rich waters which also have elevated alkali element (Li, B, K, Rb) concentrations. These alkali element-rich waters are associated with portions of the South Arkansas fault system which reach basement. Boron isotope compositions are similarly heterogeneous, ranging from values of +26 to +50%.. Brines with highest B contents are most depleted in 11B, consistent with boron input from brines generated from high-temperature siliciclastic diagenetic reactions. Normalizing B contents to Br in the brines reveals a reasonable mixing trend between a Dead Sea-type composition and Texas Gulf Coast-type shale/sand reservoir waters. Oxygen and hydrogen isotope data exhibit regional variations which are controlled by meteoric water invasion along the northern limb of the southwest Arkansas Fault, which has surface expression. Although oxygen isotope compositions are often near equilibrium with respect to reservoir carbonate, it is more difficult to ascribe trends in δD values to local water

  14. Developmentand Application of Accelerator Isotopes in China

    OpenAIRE

    YANG Yuan-you; LI Fei-ze; LIAO Jia-li; Liu, Ning

    2015-01-01

    Compared with the isotopes generated by nuclear reactor, the isotopes prepared by accelerator always show high specific activity and short half-life period. And most of such isotopes always were neutron-deficient nuclides, giving β+ or single energy γ ray. As one of the most important methods preparing radionuclides, the preparation of isotopes by accelerator has attracted more and more attention from the beginning of 21th century. The development of the preparation and application of the acc...

  15. New ab initio potential energy surface for BrH2 and rate constants for the H + HBr → H2 + Br abstraction reaction.

    Science.gov (United States)

    Jiang, Bin; Xie, Changjian; Xie, Daiqian

    2011-03-21

    A global potential energy surface (PES) for the electronic ground state of the BrH(2) system was constructed based on the multireference configuration interaction (MRCI) method including the Davidson's correction using a large basis set. In addition, the spin-orbit correction were computed using the Breit-Pauli Hamiltonian and the unperturbed MRCI wavefunctions in the Br + H(2) channel and the transition state region. Adding the correction to the ground state potential, the lowest spin-orbit correlated adiabatic potential was obtained. The characters of the new potential are discussed. Accurate initial state specified rate constants for the H + HBr → H(2) + Br abstraction reaction were calculated using a time-dependent wave packet method. The predicted rate constants were found to be in excellent agreement with the available experimental values and much better than those obtained from a previous PES.

  16. Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC

    National Research Council Canada - National Science Library

    Choi, S; Wang, Y Yuanyue; Salawitch, RJ; Canty, T; Joiner, J; Zeng, T; Kurosu, TP; Chance, K; Richter, A; Huey, LG; Liao, J; Neuman, JA; Nowak, JB; Dibb, JE; Weinheimer, AJ; Diskin, G; Ryerson, TB; Silva, A da; Curry, J; Kinnison, D; Tilmes, S; Levelt, PF Pieternel

    2012-01-01

    We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative...

  17. Optical properties of Pb-based aggregated phases in CsBr crystal

    Energy Technology Data Exchange (ETDEWEB)

    Voloshinovskii, A. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Myagkota, S. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Garapyn, I. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Stryganyuk, G. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Rodnyi, P. [St. Petersburg State Polytechnical University, 29 Polyteknicheskaya Str., 195251 St. Petersburg (Russian Federation); Eijk, C.W.E. van [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail: vaneijk@iri.tudelft.nl

    2005-01-01

    The emission and excitation spectra as well as luminescence decay kinetics of a CsBr:Pb (1.0mol%) crystal have been measured under pulsed synchrotron radiation excitation. The heat-treated ({approx}200 deg. C) crystal shows evidence of single lead centres and aggregated phases such as CsPbBr3 nanocrystals. The latter have been identified from comparison of the spectral-kinetic characteristics of the CsPbBr3 aggregated phases and single crystals. The process of energy transfer from the host to the aggregates is considered.

  18. Brändin johtamisen ja siirtohinnoittelun haasteet : case: Battery® Energy Drink

    OpenAIRE

    Tuominen, Harry

    2013-01-01

    Tämä opinnäytetyö käsittelee brändin johtamisen ja siirtohinnoittelun haasteita Oy Sinebrychoff Ab:n Battery® Energy Drink –energiajuoman kannalta. Tutkimuksen tavoitteena on selvittää Battery® Energy Drink -brändin johtamiseen ja siirtohinnoitteluun liittyviä sekä konsernin sisäisiä että konsernin ulkopuolisia haasteita. Opinnäytetyö tehdään Oy Sinebrychoff Ab:n vientiosastolle toimeksiantona. Tutkimuksen teoriaosuudessa perehdytään brändin johtamisen eri näkökulmiin ja siirtohinnoittelu...

  19. Phase topology of a NR/BR elastomer blend with active filler

    Directory of Open Access Journals (Sweden)

    Plavšić Milenko B.

    2003-01-01

    Full Text Available The relations between the structure and mechanical properties of a polymer blend of natural (NR and polybutadiene (BR rubber (i.e. a NR/BR blend with the weight ratio of the components 70/30 filled with active carbon black were analysed. The properties of the individual phases in the blend were resolved by modeling the stress-strain relationship according to the Bauer procedure for high extensions. The obtained results indicated that BR is the dispersed phase, having a higher modulus, which was also confirmed by the much better fit of the experimental data to the series type of phase coupling according to the Takanayagy theory.

  20. Stable isotopes and biomarkers in microbial ecology

    NARCIS (Netherlands)

    Boschker, H.T.S.; Middelburg, J.J.

    2002-01-01

    The use of biomarkers in combination with stable isotope analysis is a new approach in microbial ecology and a number of papers on a variety of subjects have appeared. We will first discuss the techniques for analysing stable isotopes in biomarkers, primarily gas chromatography-combustion-isotope

  1. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    In the first part of this series, we discussed how isotopes can be used as markers to determine the nature of intermediates in chemical reactions. The second part covered the effect of isotopes on equilibria and reactions, in processes where the bond to the isotopic a tom is broken. We showed with specific examples how.

  2. PSP Program close out documentation

    Energy Technology Data Exchange (ETDEWEB)

    Andringa, K.; Hootman, H.E.; Ferrara, A.S.; Smith, P.K.; Congdon, J.W.; Randolph, H.W.; Young, R.H.; Driggers, F.E.; Topp, S.V.

    1985-12-31

    In December 1982 DOE-SR directed SRL to study the feasibility and impact of a program to lower the U-236 content of the Highly Enriched Uranium (HEU) stockpile used as fuel for the SRP reactors. In response to this request SRL assessed four technologies, Atomic Vapor Laser Isotope Separation (AVLIS), Molecular Laser Isotope Separation (MLIS), Gas Centrifuge, and the Plasma Separation Process (PSP) for this purpose with the assistance of the Engineering Department. In April 1983 cost/benefit analyses for these processes, high spot cost estimates for production facilities, and process uncertainties were submitted to DOE-SR with a recommendation to proceed with the conceptual design and supporting development programs for a facility based on the use of the PSP process. The current program status for the PSP development program at SRL and the design and documentation of a production facility at SRP, referred to as the Fuel Improvement Demonstration Facility (FIDF), is described in this report.

  3. A comparative study of LaBr3(Ce(3+)) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications.

    Science.gov (United States)

    Kozyrev, A; Mitrofanov, I; Owens, A; Quarati, F; Benkhoff, J; Bakhtin, B; Fedosov, F; Golovin, D; Litvak, M; Malakhov, A; Mokrousov, M; Nuzhdin, I; Sanin, A; Tretyakov, V; Vostrukhin, A; Timoshenko, G; Shvetsov, V; Granja, C; Slavicek, T; Pospisil, S

    2016-08-01

    The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce(3+)) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce(3+)) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce(3+)) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

  4. Time dependence of the luminescence intensity in CdBr2: AgCl,PbBr2 crystals under N2-laser excitation at room temperature

    Science.gov (United States)

    Bolesta, I. M.; Kalivoshka, B. M.; Karbovnyk, I. D.; Lesivtsiv, V. M.; Novosad, I. S.; Novosad, S. S.; Rovetskyy, I. M.; Velgosh, S. R.

    2014-12-01

    Results of optical-luminescence studies of polydoped photochromic CdBr2: AgCl,PbBr2 crystals are presented. It is shown that the luminescence decrease vs. time under N2-laser excitation in the range of A-band of Pb2+ absorption is due to photochemical reactions. The empirical model describing the decrease of the luminescence related to silver impurities due to photochemical processes is suggested. Model parameters (trapping cross-section — σ — and the amount of centres destroyed by irradiation — β) were determined using the comparative analysis of experimental and calculated luminescence decay curves.

  5. Fragmentation of exotic oxygen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Leistenschneider, A.; Elze, Th.W.; Gruenschloss, A.; Palit, R. [Johann Wolfgang Goethe-Univ., Frankfurt (Germany). Inst. fuer Kernphysik; Aumann, T.; Cortina, D.; Datta Pramanik, U.; Emling, H.; Geissel, H.; Helariutta, K.; Hellstroem, M.; Ilievski, S.; Jones, K.; Muenzenberg, G.; Scheidenberger, C.; Schmidt, K.-H.; Suemmerer, K. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Boretzky, K.; Kratz, J.V.; Le Hong, Khiem [Johannes Gutenberg-Univ., Mainz (Germany). Inst. fue Kernchemie; Canto, L.F. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Carlson, B.V. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica (ITA). Dept. de Fisica; Hussein, M.S. [Sao Paulo Univ. (USP), SP (Brazil). Inst. de Fisica; Kulessa, R.; Lubkiewicz, E.; Wajda, E.; Walus, W. [Uniwersytet Jagellonski, Krakow (Poland). Instytut Fizyki; Reiter, P. [Ludwig-Maximilians-Univ., Garching (Germany). Sektion Physik; Simon, H. [Technische Univ., Darmstadt (Germany). Inst. fuer Kernphysik

    2003-06-01

    Abrasion-ablation models and the empirical EPAX parametrization of projectile fragmentation are described. Their cross section predictions are compared to recent data of the fragmentation of secondary beams of neutron-rich, unstable {sup 19,20,21} O isotopes at beam energies near 600 MeV/nucleon as well as data for stable {sup 17,18} O beams. (author)

  6. Isotope Harvesting Opportunities at FRIB

    Science.gov (United States)

    Morrissey, David

    2017-01-01

    The fragmentation of fast heavy ion beams now at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotope Beams (FRIB) under construction produce an unprecedentedly broad spectrum of radionuclides but only a small fraction are used in the on-line rare-isotope program. Projectile fragmentation facilities provide an electromagnetically purified beam of a single projectile fragment for nuclear physics experiments ranging from low energy astrophysics, through nuclear structure studies, to probing fundamental symmetries. By augmenting the NSCL and FRIB production facilities with complimentary collection and purification of discarded ions, called isotope harvesting with chemical purification, many other nuclides will become available for off-line experiments in parallel with the primary experiment. A growing user community has established a list of key target isotopes and is working with the FRIB design team to allow inclusion of necessary equipment in the future. An overview of the possibilities and the techniques will be presented in this talk. Supported by Office of Science, US DOE and Michigan State University.

  7. Charge radii of radium isotopes

    NARCIS (Netherlands)

    Wansbeek, L. W.; Schlesser, S.; Sahoo, B. K.; Dieperink, A. E. L.; Onderwater, C. J. G.; Timmermans, R. G. E.

    2012-01-01

    We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra+ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra+ are used. The nuclear radial differences delta for the radium

  8. Crystal growth and characterization of mixed lead halides PbCl2xBr2(1-x)

    NARCIS (Netherlands)

    Lumbreras, M.; Protas, J.; Jebbari, S.; Dirksen, G.J.; Schoonman, J.

    1985-01-01

    Single crystals of PbCl2-type solid solutions PbCl2xBr2(1−x) have been grown using the Bridgeman technique. XRD measurements reveal preferential site occupancy for Cl and Br, while the anion array of PbClBr is completely ordered. The temperature and composition dependence of the ionic conductivity

  9. Neodymium isotopes and the Neogene evolution of Arctic intermediate water

    Science.gov (United States)

    Haley, B. A.; Frank, M.; Spielhagen, R.

    2006-12-01

    We present the first Nd isotope record of Arctic intermediate water obtained from metal-oxide coatings weakly leached off sediments from the IODP Leg 302 (ACEX) cores drilled on the Lomonosov Ridge in the central Arctic Ocean. The ACEX cores provide the first archive of Arctic Ocean sedimentation covering most of the Cenozoic, and show that detrital sediments dominate the most recent 17 Ma, deposited above a condensed section spanning the period from ~17 to 45 Ma. Comparison of core top sediment leaches to direct seawater measurements demonstrate the Nd isotopic signal of the leaches robustly records the ambient Arctic bottom water Nd isotopic composition (typical Nd of Arctic core top sediment leachates is ~-10.5, compared with measured deep water Nd of ~-11; Andersson, Porcelli, Frank et al., unpublished). This is critical, as the Arctic sediments in the upper 200 m are essentially barren of other authigenic phases- such as carbonates - from which seawater Nd could potentially be extracted. Sampling resolution was generally low (Myr) with the exception of sections showing distinct glacial/interglacial cyclicities during the Late Quaternary, where sampling was increased to kyr resolution. This cyclicity was reproduced in the well-dated nearby piston core PS2185. The Nd isotopic variations are pronounced, for both the glacial-interglacial cycles of the Quaternary (Nd ranges from ~-7.5 to ~-10.5, respectively), and for the Nd on the million year time scale (maxima at ~-6 and minima at ~-8.5). On the long time scale, the Nd isotopic record is argued to reflect tectonically- driven changes in gateways to the Arctic. The Nd isotopic record becomes more positive from 17 to 8 Ma, reflecting the subsidence of the Greenland-Scotland Ridge with a closed Fram Strait, which increased the hydrological cycle and erosion over N.Europe/ W. Siberia. Opening of the Fram Strait at 8 Ma allowed N. Atlantic-sourced Intermediate water forming in the Greenland-Iceland-Norwegian Seas to

  10. Modeling equilibrium Fe isotope fractionation

    Science.gov (United States)

    Anbar, A.; Jarzecki, A.; Spiro, T.

    2003-04-01

    Research into the stable isotope biogeochemistry of Fe and other transition metals has been driven primarily by analytical innovations which have revealed significant isotope effects in nature and the laboratory. Further development of these new isotope systems requires complementary theoretical research to guide analytical efforts. The results of the first such studies show some discrepancies with experiments. For example, Johnson et al. (2002) report an experimentally-determined 56Fe/54Fe equilibrium fractionation factor between Fe(II) and Fe(III) aquo complexes of ˜1.0025. This effect is ˜50% smaller than predicted theoretically by Schauble et al. (2001). It is important to resolve such discrepancies. Equilibrium isotope fractionation factors can be predicted from vibrational spectroscopic data of isotopically-substituted complexes, or from theoretical predictions of some or all of these frequencies obtained using force field models. The pioneering work of Schauble et al. (2001) utilized a modified Urey-Bradley force field (MUBFF) model. This approach is limiting in at least three ways: First, it is not ab initio, requiring as input some measured vibrational frequencies. Such data are not always available, or may have significant uncertainties. Second, the MUBFF does not include potentially important effects of solvent interaction. Third, because it makes certain assumptions about molecular symmetry, the MUBFF-based approach is not able to model the spectra of mixed-ligand complexes. To address these limitations, we are evaluating the use of density functional theory (DFT) as an ab initio method to predict vibrational frequencies of isotopically-substituted complexes and, hence, equilibrium fractionation factors. In a preliminary examination of the frequency shift upon isotope substitution of the bending and asymmetric stretching modes of the tetrahedral FeCl_42- complex, we find substantial differences between MUBFF and DFT predictions. Results for other Fe

  11. Small changes in Cu redox state and speciation generate large isotope fractionation during adsorption and incorporation of Cu by a phototrophic biofilm

    Science.gov (United States)

    Coutaud, Margot; Méheut, Merlin; Glatzel, Pieter; Pokrovski, Gleb S.; Viers, Jérôme; Rols, Jean-Luc; Pokrovsky, Oleg S.

    2018-01-01

    Despite the importance of phototrophic biofilms in metal cycling in freshwater systems, metal isotope fractionation linked to metal adsorption and uptake by biofilm remains very poorly constrained. Here, copper isotope fractionation by a mature phototrophic biofilm during Cu surface adsorption and incorporation was studied in batch reactor (BR) and open drip flow reactor (DFR) systems at ambient conditions. X-ray Absorption Spectroscopy (both Near Edge Structure, XANES, and Extended Fine Structure, EXAFS) at Cu K-edge of the biofilm after its interaction with Cu in BR experiments allowed characterizing the molecular structure of assimilated Cu and quantifying the degree of CuII to CuI reduction linked to Cu assimilation. For both BR and DFR experiments, Cu adsorption caused enrichment in heavy isotope at the surface of the biofilm relative to the aqueous solution, with an apparent enrichment factor for the adsorption process, ε65Cuads, of +1.1 ± 0.3‰. In contrast, the isotope enrichment factor during copper incorporation into the biofilm (ε65Cuinc) was highly variable, ranging from -0.6 to +0.8‰. This variability of the ε65Cuinc value was likely controlled by Cu cellular uptake via different transport pathways resulting in contrasting fractionation. Specifically, the CuII storage induced enrichment in heavy isotope, whereas the toxicity response of the biofilm to Cu exposure resulted in reduction of CuII to CuI, thus yielding the biofilm enrichment in light isotope. EXAFS analyses suggested that a major part of the Cu assimilated by the biofilm is bound to 5.1 ± 0.3 oxygen or nitrogen atoms, with a small proportion of Cu linked to sulfur atoms (NS biofilm exhibited a similar trend over time of exposure. Our study demonstrates the complexity of biological processes associated with live phototrophic biofilms, which produce large and contrasting isotope fractionations following rather small Cu redox and speciation changes during uptake, storage or release of

  12. The isotopic contamination in electromagnetic isotope separators; La contagion isotopique dans les separateurs electromagnetiques d'isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Cassignol, Ch. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    In the early years of isotope separation, and in particular electromagnetic isotope separation, needs for rapid results have conducted to empiric research. This paper describes fundamental research on the electromagnetic isotope separation to a better understanding of isotope separators as well as improving the performances. Focus has been made on the study of the principle of isotope contamination and the remedial action on the separator to improve the isotope separation ratio. In a first part, the author come back to the functioning of an electromagnetic separator and generalities on isotope contamination. Secondly, it describes the two stages separation method with two dispersive apparatus, an electromagnetic separation stage followed by an electrostatic separation stage, both separated by a diaphragm. The specifications of the electrostatic stage are given and its different settings and their consequences on isotope separation are investigated. In a third part, mechanisms and contamination factors in the isotope separation are discussed: natural isotope contamination, contamination by rebounding on the collector, contamination because of a low resolution, contamination by chromatism and diffusion effect, breakdown of condenser voltage. Analysis of experimental results shows the diffusion as the most important contamination factor in electromagnetic isotope separation. As contamination factors are dependent on geometric parameters, sector angle, radius of curvature in the magnetic field and clearance height are discussed in a fourth part. The better understanding of the mechanism of the different contamination factors and the study of influential parameters as pressure and geometric parameters lead to define a global scheme of isotope contamination and determinate optima separator design and experimental parameters. Finally, the global scheme of isotope contamination and hypothesis on optima specifications and experimental parameters has been checked during a

  13. Parasiticidal effect of 16alpha-bromoepiandrosterone (EpiBr) in amoebiasis and cysticercosis.

    Science.gov (United States)

    Carrero, Julio César; Cervantes-Rebolledo, Claudia; Vargas-Villavicencio, José Antonio; Hernández-Bello, Romel; Dowding, Charles; Frincke, James; Reading, Chris; Morales-Montor, Jorge

    2010-08-01

    The effect of the dehydroepiandrosterone analog 16alpha-bromoepiandrosterone (EpiBr) was tested on the tapeworm Taenia crassiceps and the protist Entamoeba histolytica, both in vivo and in vitro. Administration of EpiBr prior to infection with cysticerci in mice reduced the parasite load by 50% compared with controls. EpiBr treatment induced 20% reduction on the development of amoebic liver abscesses in hamsters. In vitro treatment of T. crassiceps and E. histolytica cultures with EpiBr, reduced reproduction, motility and viability in a dose- and time-dependent fashion. These results leave open the possibility of assessing the potential of this hormonal analog as a possible anti-parasite drug, including cysticercosis and amoebiasis. Copyright 2010 Elsevier Masson SAS. All rights reserved.

  14. Best Western - tuntud ja tunnustatud ülemaailmne hotelliketi bränd

    Index Scriptorium Estoniae

    2012-01-01

    1946. aastal Californias M. K. Guertini poolt asutatud Best Western hotelliketist, mis pakub just sõltumatutele hotellipidajatele ühtset turundus- ja müügistrateegiat, brändi- ja teeninduskontseptsiooni

  15. Longpath DOAS observations of surface BrO at Summit, Greenland

    Directory of Open Access Journals (Sweden)

    J. Stutz

    2011-09-01

    Full Text Available Reactive halogens, and in particular bromine oxide (BrO, have frequently been observed in regions with large halide reservoirs, for example during bromine catalyzed coastal polar ozone depletion events. Much less is known about the presence and impact of reactive halogens in areas without obvious halide reservoirs, such as the polar ice sheets or continental snow. <br>> We report the first LP-DOAS measurements of BrO at Summit research station in the center of the Greenland ice sheet at an altitude of 3200 m. BrO mixing ratios in May 2007 and June 2008 were typically between 1–3 pmol mol−1, with maxima of up to 5 pmol mol−1. These measurements unequivocally show that halogen chemistry is occurring in the remote Arctic, far from known bromine reservoirs, such as the ocean. During periods when FLEXPART retroplumes show that airmasses resided on the Greenland ice sheet for 3 or more days, BrO exhibits a clear diurnal variation, with peak mixing ratios of up to 3 pmol mol−1 in the morning and at night. The diurnal cycle of BrO can be explained by a changing boundary layer height combined with photochemical formation of reactive bromine driven by solar radiation at the snow surface. The shallow stable boundary layer in the morning and night leads to an accumulation of BrO at the surface, leading to elevated BrO despite the expected smaller release from the snowpack during these times of low solar radiation. During the day when photolytic formation of reactive bromine is expected to be highest, efficient mixing into a deeper neutral boundary layer leads to lower BrO mixing ratios than during mornings and nights. <br>> The extended period of contact with the Greenland snowpack combined with the diurnal profile of BrO, modulated by boundary layer height, suggests that photochemistry in the snow is a significant source of BrO measured at Summit during the 2008 experiment. In addition, a rapid transport event

  16. Atmospheric lifetime of CHF sub 2 Br, a proposed substitute for halons

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, R.; Mellouki, A.; Gierczak, T.; Burkholder, J.B.; McKeen, S.A.; Ravishankara, A.R. (National Oceanic and Atmospheric Administration, Boulder, CO (United States) Univ. of Colorado, Boulder (United States))

    1991-05-03

    The rate coefficients, k{sub 1}, for the reaction of OH with CHF{sub 2}Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be k{sub 1} = (7.4 {plus minus} 1.6) {times} 10{sup {minus}13} exp({minus}(1,300 {plus minus} 100)/T) cubic centimeters per molecule per second. The ultraviolet absorption cross sections, {sigma}, of this molecule between 190 and 280 nanometers were measured at 296 K. The k{sub 1} and {sigma} values were used in a one-dimensional model to obtain an atmospheric lifetime of approximately 7 years for CHF{sub 2}Br. This lifetime is shorter by approximately factors of 10 and 2 than those for CF{sub 3}Br and CF{sub 2}ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these lifetimes.

  17. Eesti ajaloo kotkaperspektiivist : minu vaidlus Brüggermanniga / Jaan Undusk

    Index Scriptorium Estoniae

    Undusk, Jaan, 1958-

    2002-01-01

    Märkusi Jaan Unduski "metahistooriliste" zhestide kohta, varasema eestikeelse kirjanduse seotusest baltisaksa kirjandusega. Artiklist - Brüggemann, Karl. Rahvusliku vaenlasekuju demontaazhist ehk Carl Schirren kui Eesti iseseisvuse rajaja? // Tuna, 2002, nr. 3, lk. 93-98

  18. Kallas valmistus Brüsselis voliniku tööks / Ahto Lobjakas

    Index Scriptorium Estoniae

    Lobjakas, Ahto, 1970-

    2004-01-01

    Siim Kallas kohtus Brüsselis Euroopa Komisjoni presidendi Romano Prodi ning komisjoni volinikega. Suure tõenäosusega saab Kallas oma juhendajaks ettevõtluse ja infoühiskonna valdkonnaga tegeleva Erkki Liikaneni

  19. Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics

    Science.gov (United States)

    Burt, Michael; Boll, Rebecca; Lee, Jason W. L.; Amini, Kasra; Köckert, Hansjochen; Vallance, Claire; Gentleman, Alexander S.; Mackenzie, Stuart R.; Bari, Sadia; Bomme, Cédric; Düsterer, Stefan; Erk, Benjamin; Manschwetus, Bastian; Müller, Erland; Rompotis, Dimitrios; Savelyev, Evgeny; Schirmel, Nora; Techert, Simone; Treusch, Rolf; Küpper, Jochen; Trippel, Sebastian; Wiese, Joss; Stapelfeldt, Henrik; de Miranda, Barbara Cunha; Guillemin, Renaud; Ismail, Iyas; Journel, Loïc; Marchenko, Tatiana; Palaudoux, Jérôme; Penent, Francis; Piancastelli, Maria Novella; Simon, Marc; Travnikova, Oksana; Brausse, Felix; Goldsztejn, Gildas; Rouzée, Arnaud; Géléoc, Marie; Geneaux, Romain; Ruchon, Thierry; Underwood, Jonathan; Holland, David M. P.; Mereshchenko, Andrey S.; Olshin, Pavel K.; Johnsson, Per; Maclot, Sylvain; Lahl, Jan; Rudenko, Artem; Ziaee, Farzaneh; Brouard, Mark; Rolles, Daniel

    2017-10-01

    The dynamics following laser-induced molecular photodissociation of gas-phase CH2BrI at 271.6 nm were investigated by time-resolved Coulomb-explosion imaging using intense near-IR femtosecond laser pulses. The observed delay-dependent photofragment momenta reveal that CH2BrI undergoes C-I cleavage, depositing 65.6% of the available energy into internal product states, and that absorption of a second UV photon breaks the C-Br bond of CH2Br . Simulations confirm that this mechanism is consistent with previous data recorded at 248 nm, demonstrating the sensitivity of Coulomb-explosion imaging as a real-time probe of chemical dynamics.

  20. Kuidas eristavad ostjad Eesti brände? / Lele Aak, Aivar Voog

    Index Scriptorium Estoniae

    Aak, Lele

    2003-01-01

    Eesti Konverentsikeskuse ja Emori koostöös läbi viidud uuringust eesmärgiga selgitada välja Eesti turundusspetsialistide arvamus brändide eristumisekohta Diagrammid. Kommenteerib Endrik Randoja.

  1. BrO vertical distributions from SCIAMACHY limb measurements: comparison of algorithms and retrieval results

    Directory of Open Access Journals (Sweden)

    A. Rozanov

    2011-07-01

    Full Text Available This study presents two scientific and one operational retrieval algorithms used to obtain vertical distributions of bromine monoxide (BrO from observations of the scattered solar light performed by the SCIAMACHY instrument in limb viewing geometry. The study begins with a discussion of the theoretical basis of all algorithms followed by an investigation of the retrieval sensitivity. Simulations with three different radiative transfer models allow us to analyze influence of the forward model implementation upon the retrieval results. By means of synthetic retrievals we analyze major sources of uncertainties in the resulting BrO profiles such as different BrO cross sections, their temperature dependence, and stratospheric aerosols. Finally, the reliability of SCIAMACHY BrO profile retrievals is demonstrated comparing results from different algorithms to each other and to balloon-borne observations.

  2. [Memel als Brücke zu den baltischen Ländern] / Ralph Tuchtenhagen

    Index Scriptorium Estoniae

    Tuchtenhagen, Ralph, 1961-

    2014-01-01

    Arvustus: Memel als Brücke zu den baltischen Ländern. Kulturgeschichte Klaipedas vom Mittelalter bis ins 20. Jahrhundert. (Tagungsberichte der Historischen Kommission für ost- und westpreussische Landesforschung. Bd. 26)

  3. Brüsselis kõneldi GMO vastu / Nastja Pertsjonok

    Index Scriptorium Estoniae

    Pertsjonok, Nastja

    2005-01-01

    Brüsselis toimunud konverentsil nõudsid Euroopa Liidu maade regionaalministrid ja Europarlamendi liikmed õigust otsustada geneetiliselt muundatud põllukultuuride keelamise üle piirkondlikul tasandil

  4. High yield direct 76Br-bromination of monoclonal antibodies using chloramine-T.

    Science.gov (United States)

    Sundin, J; Tolmachev, V; Koziorowski, J; Carlsson, J; Lundqvist, H; Welt, S; Larson, S; Sundin, A

    1999-11-01

    Monoclonal antibody (MAb) A33 was labeled with the positron emitter 76Br (T(1/2) = 16.2 h). Direct labeling was done using the conventional chloramine-T method. After optimization of the labeling conditions, a maximum yield (mean +/- max error) of 77 +/- 2% was obtained at pH 6.8. In vitro binding of 76Br-A33 to SW1222 colonic cancer cells showed that the immunoreactivity was retained. Also, the MAbs 38S1 and 3S193 and the peptide hEGF were 76Br-labeled, resulting in labeling yields (mean +/- max error) of 75 +/- 3%, 63 +/- 4%, and 73 +/- 0.1%, respectively. We conclude that antibodies and peptides can be labeled conveniently with 76Br for the purpose of whole-body tumour imaging by positron emission tomography.

  5. Isotopic Compositions of the Elements 1989

    Science.gov (United States)

    De Laeter, J. R.; Heumann, K. G.; Rosman, K. J. R.

    1991-11-01

    The Subcommittee for Isotopic Abundance Measurements (SIAM) of the IUPAC Commission on Atomic Weights and Isotopic Abundances has carried out its biennial review of isotopic compositions, as determined by mass spectrometry and other relevant methods. The Subcommittee's critical evaluation of the published literature element by element forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry 1989, which is presented in this Report. Atomic Weights calculated from the tabulated isotopic abundances are consistent with Ar(E) values listed in the Table of Standard Atomic Weights 1989.

  6. Stable isotope compounds - production, detection, and application.

    Science.gov (United States)

    Zachleder, Vilém; Vítová, Milada; Hlavová, Monika; Moudříková, Šárka; Mojzeš, Peter; Heumann, Hermann; Becher, Johannes R; Bišová, Kateřina

    2018-01-19

    Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies. Copyright © 2018. Published by Elsevier Inc.

  7. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.

    2010-12-01

    Full Text Available Modelling of stable water isotopes H2 18O and HDO within various parts of the Earth’s hydrological cycle has clearly improved our understanding of the interplay between climatic variations and related isotope fractionation processes. In this article key principles and major research results of stable water isotope modelling studies are described. Emphasis is put on research work using explicit isotope diagnostics within general circulation models as this highly complex model setup bears many resemblances with studies using simpler isotope modelling approaches.

  8. Nomenclatural notes on the Eurytomids (Chalcidoidea: Eurytomidae) described by Jean Brèthes housed in Museo Argentino de Ciencias Naturales "Bernardino Rivadavia".

    Science.gov (United States)

    Gates, Michael W

    2014-04-16

    Ten Eurytomidae (Hymenoptera) parasitic wasp species described by Jean Brèthes and deposited in the Museo Argentino de Ciencias Naturales in Buenos Aires are treated and their nomenclature stabilized. The condition of the type material is described. Lectotypes are designated for Decatoma cecidosiphaga Brèthes, Prodecatoma parodii Brèthes, Eudecatoma opposita Brèthes, and Eurytoma caridei Brèthes. One new generic synonymy, Xanthosomodes Brèthes with Tetramesa Walker, n. syn., and five new combinations are proposed: Tetramesa albiangulata (Brèthes), n. comb.; Phylloxeroxenus caridei (Brèthes), n. comb.; Aximopsis vulgata (Brèthes), n. comb.; Proseurytoma parodii (Brèthes), n. comb.; and Bruchophagus opposita (Brèthes), n. comb. Sycophila paranensis Brèthes is declared incertae sedis.

  9. Direct conversion of methane to higher hydrocarbons using AlBr3-HBr superacid catalyst.

    Science.gov (United States)

    Vasireddy, Sivakumar; Ganguly, Sreemoyee; Sauer, Joe; Cook, Wyndham; Spivey, James J

    2011-01-14

    The direct gas phase catalytic oligomerization of methane at temperatures ≤673 K has been demonstrated using AlBr(3)-HBr superacid. The reaction produces C(2)+ hydrocarbons and hydrogen in a single step at 1 atm in a continuous flow reactor at a nominal residence time of 60 s. The essentially complete conversion of methane appears to be due to protolytic activation of methane in the presence of H(+)AlBr(4)(-).

  10. Thermogalvanic effects on the corrosion of copper in heavy brine LiBr solutions

    OpenAIRE

    Fernández Domene, Ramón Manuel; Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José

    2012-01-01

    Thermogalvanic corrosion of copper in heavy brine LiBr solutions has been investigated using a zero-resistance ammeter (ZRA). The temperature gradients between copper electrodes immersed in the same LiBr solution result in the formation of thermogalvanic cells with hot anodes, leading to high and sustained thermogalvanic currents. Copper loss rates, calculated using Faraday's law, substantially exceed 0.025mmyear -1, a value regarded as the threshold of low corrosion rates. The effects of the...

  11. Thermodynamic and structural properties of high temperature solid and liquid EuBr2

    DEFF Research Database (Denmark)

    Rycerz, L.; Gadzuric, S.; Ingier-Stocka, E.

    2005-01-01

    Heat capacity of solid and liq. EuBr2 was measured by differential scanning calorimetry in the temp. range 300-1100 K. The temp. and enthalpy of fusion were also detd. exptl. By combination of these results with the literature data on the entropy at 298.15 K, S(o,m) (EuBr2, s, 298.15 K) , and the...

  12. Super-high photocatalytic activity, stability and improved photocatalytic mechanism of monodisperse AgBr doped with In

    Energy Technology Data Exchange (ETDEWEB)

    Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Shujuan, E-mail: zhangshujuan@tust.edu.cn [College of Science, Tianjin University of Science & Technology, Tianjin 300457 (China); Zhang, Shuna [College of Textile Engineering, Zhejiang Industry Polytechnic College, Shaoxing 312000 (China)

    2015-12-15

    Highlights: • In(III)-AgBr with higher photodegradation ability was synthesized successfully. • ·OH radicals and Br{sup 0} were the main active species in the oxidation of MO. • In(III) substantially reduced the recombination rate of photon-generated carriers. - Abstract: Monodisperse In{sup 3+} doped AgBr (In-AgBr) nanoparticles were synthesized by a hydrothermal route. The pure AgBr and In-AgBr samples were investigated by X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. In-AgBr was more photocatalytically active than pure AgBr in photodegradation of 20 mg/L methyl orange under visible light irradiation (λ > 420 nm). The 0.05 mol/L In-AgBr sample showed the highest photodegradation efficiency and high stability. The doped In{sup 3+} expanded the light absorption range, reduced the band gap of AgBr and improved the utilization of photons. The additional In{sup 3+} can inhibit the formation of Ag particles on the surface of AgBr, which can further stabilize AgBr. The doped In{sup 3+} in AgBr served as a temporary site for trapping of photoinduced electrons, and thereby obviously restrained the recombination of photoinduced electron-hole pairs on the surface of AgBr. The enhanced photocatalytic ability of In-AgBr may be mainly attributed to the improved separation efficiency of photogenerated charges.

  13. Zinc isotopic compositions of breast cancer tissue.

    Science.gov (United States)

    Larner, Fiona; Woodley, Laura N; Shousha, Sami; Moyes, Ashley; Humphreys-Williams, Emma; Strekopytov, Stanislav; Halliday, Alex N; Rehkämper, Mark; Coombes, R Charles

    2015-01-01

    An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.

  14. Measuring SNM Isotopic Distributions using FRAM

    Energy Technology Data Exchange (ETDEWEB)

    Geist, William H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  15. Cross section measurements of {sup 75}As(α,xn){sup 76,77,78}Br and {sup 75}As(α,x){sup 74}As nuclear reactions using the monitor radionuclides {sup 67}Ga and {sup 66}Ga for beam evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Breunig, Katharina; Spahn, Ingo; Spellerberg, Stefan; Scholten, Bernhard; Coenen, Heinz H. [Forschungszentrum Juelich (Germany). Inst. for Neuroscience and Medicine, INM-5: Nuclear Chemistry; Hermanne, Alex [Vrije Univ. Brussel (VUB) (Belgium). Cyclotron Lab.

    2017-08-01

    For the production of the medically interesting radionuclides {sup 76}Br and {sup 77}Br cross sections of α-particle induced reactions on arsenic, leading to the formation of {sup 76,77,78}Br as well as to the non-isotopic impurity {sup 74}As, were measured from their thresholds up to 37 MeV. Sediments of elemental arsenic were used as targets and irradiated, using the established stacked-foil technique. In order to remove discrepancies of the existing literature data, the cross section ratios of the monitor nuclides {sup 67}Ga/{sup 66}Ga were used for determination of the α-particle energies as well as the effective beam current through all the stacks, thus inferring the experimental cross sections. Compared with the available excitation functions the new data indicate slightly divergent curve shapes. In the case of {sup 76}Br the excitation function seems to be shifted to somewhat lower α-particle energies, and also the maximum cross section of the formation of {sup 77}Br tends to be slightly lower compared with the curve recommended to date. In the case of a re-evaluation, these new data should be taken into account, as they may contribute to enhance the accuracy of the excitation functions.

  16. Effect of antiorthostatic BedRest (BR) on GastroIntestinal Motility (GIM) of normal subjects

    Science.gov (United States)

    Putcha, L.; Hunter, R. P.; Tietze, K. J.; Cintron, N. M.

    1992-01-01

    The combined effects of postural changes, fluid shifts and diuresis associated with the absence of the gravity vector may decrease gastrointestinal motility (GIM) during space flight. GIM can be estimated from the mouth to cecum transit time (MCTT) of orally administered lactulose (LAC); this test is used to assess changes in GIM in normal subjects and in patients with GI pathology and related disease conditions. Since bedrest (BR) mimics some of the physiological changes that occur during space flight, the effect of ten days of BR on GIM was evaluated from the MCTT of LAC. Methods: Subjects were 12 nonsmoking males between the ages of 35 and 50. After an 8-10 hour fast, subjects ingested Cephulac (registered) (20 g solution) with a low-fiber breakfast on four different days (45, 30, 25, and 20) before BR and on three separate days (4, 7, and 10) during BR. Breath-H2 concentrations were measured before and at 10 minute intervals for 4 hours after breakfast using a Quintron breathalyzer and MCTT was determined from these data. Results: MCTT ranged between 10 and 122 minutes during ambulation and 80 to 120 minutes during BR with means of 79 minutes and 122 minutes respectively. Conclusion: Mean MCTT during BR was 54 percent longer than during ambulation, suggesting that absorption and availability of orally administered medications and nutrients may be delayed or impaired as a result of decreased GIM during bedrest.

  17. Enriching Glucoraphanin in Brassica rapa Through Replacement of BrAOP2.2/BrAOP2.3 with Non-functional Genes

    Directory of Open Access Journals (Sweden)

    Zhiyuan Liu

    2017-08-01

    Full Text Available Sulforaphane, the hydrolytic product of glucoraphanin glucosinolate, is a potent anticarcinogen that reduces the risk of several human cancers. However, in most B. rapa vegetables, glucoraphanin is undetectable or only present in trace amounts, since the glucoraphanin that is present is converted to gluconapin by three functional BrAOP2 genes. In this study, to enrich beneficial glucoraphanin content in B. rapa, the functional BrAOP2 alleles were replaced by non-functional counterparts through marker-assisted backcrossing (MAB. We identified non-functional mutations of two BrAOP2 genes from B. rapa. The backcross progenies with introgression of both non-functional braop2.2 and braop2.3 alleles significantly increased the glucoraphanin content by 18 times relative to the recurrent parent. In contrast, replacement or introgression of single non-functional braop2.2 or braop2.3 locus did not change glucoraphanin content. Our results suggest that replacement of these two functional BrAOP2 genes with non-functional alleles has the potential for producing improved Brassica crops with enriched beneficial glucoraphanin content.

  18. Precision measurement of the ratio BR($K_{S} \\to \\pi^{+}\\pi^{-}e^{+}e^{-}$)/BR($K_{L} \\to \\pi^{+}\\pi^{-}\\pi^{0}_{D}$)

    CERN Document Server

    Batley, J R; Lazzeroni, C; Munday, D J; Patel, M; Slater, M W; Wotton, S A; Arcidiacono, R; Bocquet, G; Ceccucci, A; Cundy, D; Doble, N; Falaleev, V; Gatignon, L; Gonidec, A; Grafström, P; Kubischta, W; Marchetto, F; Mikulec, I; Norton, A; Panzer-Steindel, B; Rubin, P; Wahl, H; Goudzovski, E; Hristov, P; Kekelidze, V; Kozhuharov, V; Litov, L; Madigozhin, D; Molokanova, N; Potrebenikov, Yu.; Stoynev, S; Zinchenko, A; Monnier, E; Swallow, E C; Winston, R; Sacco, R; Walker, A; Baldini, W; Dalpiaz, P; Frabetti, P L; Gianoli, A; Martini, M; Petrucci, F; Scarpa, M; Savrié, M; Bizzeti, A; Calvetti, M; Collazuol, E; Iacopini, E; Lenti, M; Ruggiero, G; Veltri, M; Behler, M; Eppard, K; Eppard, M; Hirstius, A; Kleinknecht, K; Koch, U; Marouelli, P; Masetti, L; Moosbrugger, U; Morales Morales, C; Peters, A; Wanke, R; Winhart, A; Dabrowski, A; Fonseca Martin, T; Szleper, M; Velasco, M; Anzivino, G; Cenci, P; Imbergamo, E; Lamanna, G; Lubrano, P; Michetti, A; Nappi, A; Pepe, M; Petrucci, M C; Piccini, M; Valdata, M; Cerri, C; Costantini, F; Fantechi, R; Fiorini, L; Giudici, S; Mannelli, I; Pierazzini, G; Sozzi, M; Cheshkov, C; Chèze, J B; De Beer, M; Debu, P; Gouge, G; Marel, G; Mazzucato, E; Peyaud, B; Vallage, B; Holder, M; Maier, A; Ziolkowski, M; Biino, C; Cartiglia, N; Clemencic, M; Goy Lopez, S; Menichetti, E; Pastrone, N; Wislicki, W; Dibon, H; Jeitler, M; Markytan, M; Neuhofer, G; Widhalm, L

    2011-01-01

    The $K_{S} \\rightarrow \\pi^{+}\\pi^{-}e^{+}e^{-}$ decay mode was investigated using the data collected in 2002 by the NA48/1 collaboration. With about 23,k $K_{S} \\rightarrow \\pi^{+}\\pi^{-}e^{+}e^{-}$ events and 59,k $K_{L} \\rightarrow \\pi^{+}\\pi^{-}\\pi^{0}_{D}$ normalization decays, the $K_{S} \\rightarrow \\pi^{+}\\pi^{-}e^{+}e^{-}$ branching ratio relative to the $K_{L}\\rightarrow \\pi^{+}\\pi^{-}\\pi^{0}_{D}$ one was determined to be BR($K_{S} \\rightarrow \\pi^{+}\\pi^{-}e^{+}e^{-}$)/BR($K_{L} \\rightarrow \\pi^{+}\\pi^{-}\\pi^{0}_{D}$) = $ (3.28 \\pm 0.06_{stat}\\pm 0.04_{syst})\\times 10^{-2}$. This result was used to set the upper limit $|g_{E1}/g_{BR}| \\lt 3.0$ at $90%$ CL on the presence, in the decay amplitude, of an E1 direct emission ($g_{E1}$) term relative to the dominant inner bremsstrahlung ($g_{BR}$) term. The CP-violating asymmetry ${cal A}_{\\phi}$ in the sin$\\phi$,cos$\\phi$ distribution of $K_{S} \\rightarrow \\pi^{+}\\pi^{-}e^{+}e^{-}$ events, where $\\phi$ is the angle between the $\\pi^{+} \\pi^{-}$ and the $...

  19. Precision measurement of the ratio BR (KS →π+π-e+e-) / BR (KL →π+π-πD0)

    Science.gov (United States)

    Batley, J. R.; Kalmus, G. E.; Lazzeroni, C.; Munday, D. J.; Patel, M.; Slater, M. W.; Wotton, S. A.; Arcidiacono, R.; Bocquet, G.; Ceccucci, A.; Cundy, D.; Doble, N.; Falaleev, V.; Gatignon, L.; Gonidec, A.; Grafström, P.; Kubischta, W.; Marchetto, F.; Mikulec, I.; Norton, A.; Panzer-Steindel, B.; Rubin, P.; Wahl, H.; Goudzovski, E.; Hristov, P.; Kekelidze, V.; Kozhuharov, V.; Litov, L.; Madigozhin, D.; Molokanova, N.; Potrebenikov, Yu.; Stoynev, S.; Zinchenko, A.; Monnier, E.; Swallow, E. C.; Winston, R.; Sacco, R.; Walker, A.; Baldini, W.; Dalpiaz, P.; Frabetti, P. L.; Gianoli, A.; Martini, M.; Petrucci, F.; Savrié, M.; Scarpa, M.; Calvetti, M.; Collazuol, G.; Iacopini, E.; Ruggiero, G.; Bizzeti, A.; Lenti, M.; Veltri, M.; Behler, M.; Eppard, K.; Eppard, M.; Hirstius, A.; Kleinknecht, K.; Koch, U.; Marouelli, P.; Masetti, L.; Moosbrugger, U.; Morales Morales, C.; Peters, A.; Wanke, R.; Winhart, A.; Dabrowski, A.; Fonseca Martin, T.; Szleper, M.; Velasco, M.; Anzivino, G.; Imbergamo, E.; Lamanna, G.; Lubrano, P.; Michetti, A.; Nappi, A.; Piccini, M.; Valdata-Nappi, M.; Cenci, P.; Pepe, M.; Petrucci, M. C.; Cerri, C.; Fantechi, R.; Mannelli, I.; Costantini, F.; Fiorini, L.; Giudici, S.; Pierazzini, G.; Sozzi, M.; Cheshkov, C.; Chèze, J. B.; De Beer, M.; Debu, P.; Gouge, G.; Marel, G.; Mazzucato, E.; Peyaud, B.; Vallage, B.; Holder, M.; Maier, A.; Ziolkowski, M.; Biino, C.; Cartiglia, N.; Clemencic, M.; Lopez, S. Goy; Menichetti, E.; Pastrone, N.; Wislicki, W.; Dibon, H.; Jeitler, M.; Markytan, M.; Neuhofer, G.; Widhalm, L.; NA48/1 Collaboration

    2011-01-01

    The KS →π+π-e+e- decay mode was investigated using the data collected in 2002 by the NA48/1 Collaboration. With about 23 k KS →π+π-e+e- events and 59 k KL →π+π-πD0 normalization decays, the KS →π+π-e+e- branching ratio relative to the KL →π+π-πD0 one was determined to be BR (KS →π+π-e+e-) / BR (KL →π+π-πD0) = (3.28 ±0.06stat ±0.04syst) ×10-2. This result was used to set the upper limit |gE1 /gBR | < 3.0 at 90% CL on the presence, in the decay amplitude, of an E1 direct emission (gE1) term relative to the dominant inner bremsstrahlung (gBR) term. The CP-violating asymmetry Aϕ in the sin ϕcos ϕ distribution of KS →π+π-e+e- events, where ϕ is the angle between the π+π- and the e+e- decay planes in the kaon centre of mass, was found to be Aϕ = (- 0.4 ± 0.8)%, consistent with zero. These results are in good agreement with a description of the KS →π+π-e+e- decay amplitude dominated by the CP-even inner bremsstrahlung process.

  20. Measurement of BR(Bu to phi K)/BR(Bu to J/psi K) at the collider detector at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Napora, Robert A. [Johns Hopkins Univ., Baltimore, MD (United States)

    2004-01-01

    This thesis presents evidence for the decay mode B± → ΦK± in p$\\bar{p}$ collisions at √s = 1.96 TeV using (120 ± 7)pb-1 of data collected by the Collider Detector at Fermilab (CDF). This signal is then used to measure the branching ratio relative to the decay mode B± → J/ΨK±. The measurement starts from reconstructing the two decay modes: B± → ΦK±, where Φ → K+K- and B± → J/ΨK±, where J/Ψ → μ+μ-. The measurement yielded 23 ± 7 B± → ΦK± events, and 406 ± 26 B± → J/ΨK± events. The fraction of B± → J/ΨK± events where the J/Ψ subsequently decayed to two muons (as opposed to two electrons) was found to be fμμ = 0.839 ± 0.066. The relative branching ratio of the two decays is then calculated based on the equation: BR(B± → ΦK±)/BR(B± → J/ΨK±) = N ΦK/NΨK • fμμ BR(J/Ψ → μ+μ-)/BR(Φ → K+K-) ϵμμK/ϵKKK R(ϵiso). The measurement finds BR(B± → ΦK±)/BR(B± → J/ΨK±) = 0.0068 ± 0.0021(stat.) ± 0.0007(syst.). The B± → ΦK± branching ratio is then found to be BR(B± → ΦK±) = [6.9 ± 2.1(stat.) ± 0.8(syst.)] x 10-6. This value is consistent with similar measurements reported by the e+e- collider experiments BaBar[1], Belle[2], and CLEO[3].

  1. Methane clumped isotopes: Progress and potential for a new isotopic tracer

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, Peter M. J.; Stolper, Daniel A.; Eiler, John M.; Sessions, Alex L.; Lawson, Michael; Shuai, Yanhua; Bishop, Andrew; Podlaha, Olaf G.; Ferreira, Alexandre A.; Santos Neto, Eugenio V.; Niemann, Martin; Steen, Arne S.; Huang, Ling; Chimiak, Laura; Valentine, David L.; Fiebig, Jens; Luhmann, Andrew J.; Seyfried, William E.; Etiope, Giuseppe; Schoell, Martin; Inskeep, William P.; Moran, James J.; Kitchen, Nami

    2017-11-01

    The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding hydrocarbon systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a potentially valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. We review different processes affecting methane clumped isotope compositions, describe the relationships between conventional isotope and clumped isotope data, and summarize the types of information that this measurement can provide in different Earth and planetary environments.

  2. Study of the Doubly-closed Shell Nucleus $^{132}$Sn and its Valence Nuclei

    CERN Multimedia

    2002-01-01

    The aim of the experiment is to study the level structure of nuclei close to the shell closures (Z,N)~=~(50,50) and (50,82). \\\\ \\\\ The decay of the isotopes |9|8Cd, |1|3|2In, |1|3|3In and|1|3|1Cd are invesigated by means of $\\gamma$; electron- and neutron spectroscopy. Gamma-gamma and electron-gamma coincidences are also recorded.\\\\ \\\\ The experimental equipment (Ge(Li) detectors, Si(Li) detectors and |3He neutron spectrometers) are connected on-line to the ISOLDE on-line isotope separator.

  3. Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism

    Science.gov (United States)

    2016-01-01

    . Importantly, it will detail how this development has been closely aligned to the technological development within the area of mass spectrometry. Without the dedicated development provided by these mass spectrometrists over the past century, the use of stable isotope tracers within the field of protein metabolism would not be as widely applied as it is today, this relationship will no doubt continue to flourish in the future and stable isotope tracers will maintain their importance as a tool within the biological sciences for many years to come. © 2016 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Mass Spec Rev PMID:27182900

  4. New retrieval of BrO from SCIAMACHY limb: an estimate of the stratospheric bromine loading during April 2008

    Directory of Open Access Journals (Sweden)

    J. P. Parrella

    2013-10-01

    Full Text Available We present a new retrieval of stratospheric BrO (bromine monoxide from channel 2 SCIAMACHY (SCanning Imaging Absorption spectrometer for Atmospheric CHartographY limb observations. Retrievals are shown to agree with independent balloon observations to within one standard deviation of the retrieval noise. We retrieve BrO profiles for all of April 2008, and apply simulated [BrO]/[Bry] (bromine monoxide : stratospheric inorganic bromine ratios to estimate the stratospheric Bry loading. We find 23.5 ± 6 ppt Br, suggesting 7 ppt Br from short-lived bromocarbons to be at the high end of the current best estimate (3–8 ppt. The 6 ppt Br uncertainty estimate is dominated by the 21% uncertainty in the simulated [BrO] / [Bry] ratio due to propagation of errors from the underlying chemical kinetics.

  5. Trophic structure in a seabird host-parasite food web: insights from stable isotope analyses.

    Directory of Open Access Journals (Sweden)

    Elena Gómez-Díaz

    Full Text Available Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C ((13C/(12C, delta(13C and N ((15N/(14N, delta(15N of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters. delta(13C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in delta(15N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5 per thousand depending on the species. Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems.

  6. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead

    Science.gov (United States)

    Yang, Sha; Liu, Yun

    2015-01-01

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs. PMID:26224248

  7. Competition of Invertebrates Mixed Culture in the Closed Aquatic System

    Science.gov (United States)

    Pisman, Tamara

    The study considers the experimental model of interactions between invertebrates (the cilates Paramecium caudatum, Paramecium bursaria and the rotifers Brachionis plicatilis) in the closed aquatic system. The infusoria P.caudatum can feed on yeast, bacteria and chlorella; in this experiment growth and reproduction were maintained by bacteria only. The P.bursaria - zoochlorella endosymbiosis is a natural model of a simple biotic cycle. P.bursaria consumes glucose and oxygen released by zoochlorella in the process of biosynthesis and releases nitrogenous compounds and carbon dioxide necessary for algal photosynthesis. The rotifers Br. plicatilis can consume algae, bacteria and detritus. Thus in experiment with the mixed culture of invertebrates they can use different food sources. However with any initial percentage of the invertebrates the end portion of P.bursaria reaches 90-99

  8. Anthropogenic lead isotopes in Antarctica

    Science.gov (United States)

    Rosman, K. J. R.; Chisholm, W.; Boutron, C. F.; Candelone, J.-P.; Patterson, C. C.

    1994-12-01

    We report the first measurements of Pb isotopes in Antarctic snow, which show that even recent snow containing 2.3 pg/g is highly polluted with anthropogenic Pb. This follows from a comparison of isotope abundances of Pb in surface snow and terrestrial dust extracted from ancient Antarctic ice (Dome C, depth 308 m, approximate age 7,500 a BP), the latter being distinctly more radiogenic. This result is dependent of geochemical arguments based on measurements of Al, Na and SO4. South America is suggested as a likely source of this anthropogenic Pb. The presence of significantly less radiogenic Pb in the snow adjacent to two Antarctic base stations indicates that there is contamination from station emissions, although emission from Australia is an alternative explanation for a site 33 km from Dumont d'Urville.

  9. Ca isotopic geochemistry of an Antarctic aquatic system

    Science.gov (United States)

    Lyons, W. Berry; Bullen, Thomas D.; Welch, Kathleen A.

    2017-01-01

    The McMurdo Dry Valleys, Antarctica, are a polar desert ecosystem. The hydrologic system of the dry valleys is linked to climate with ephemeral streams that flow from glacial melt during the austral summer. Past climate variations have strongly influenced the closed-basin, chemically stratified lakes on the valley floor. Results of previous work point to important roles for both in-stream processes (e.g., mineral weathering, precipitation and dissolution of salts) and in-lake processes (e.g., mixing with paleo-seawater and calcite precipitation) in determining the geochemistry of these lakes. These processes have a significant influence on calcium (Ca) biogeochemistry in this aquatic ecosystem, and thus variations in Ca stable isotope compositions of the waters can aid in validating the importance of these processes. We have analyzed the Ca stable isotope compositions of streams and lakes in the McMurdo Dry Valleys. The results validate the important roles of weathering of aluminosilicate minerals and/or CaCO3 in the hyporheic zone of the streams, and mixing of lake surface water with paleo-seawater and precipitation of Ca-salts during cryo-concentration events to form the deep lake waters. The lakes in the McMurdo Dry Valleys evolved following different geochemical pathways, evidenced by their unique, nonsystematic Ca isotope signatures.

  10. Hafnium isotope results from mid-ocean ridges and Kerguelen.

    Science.gov (United States)

    Patchett, P.J.

    1983-01-01

    176Hf/177Hf ratios are presented for oceanic volcanic rocks representing both extremes of the range of mantle Hf-Nd-Sr isotopic variation. Hf from critical mid-ocean ridge basalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/Sr-Sm/Nd-Lu/Hf fractionation relationships. At the other extreme of mantle isotopic compositions, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of Hf-Nd-Sr isotopic relatonships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean-island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation.-G.R.

  11. Zinc isotope fractionation during mantle melting and constraints on the Zn isotope composition of Earth's upper mantle

    Science.gov (United States)

    Wang, Ze-Zhou; Liu, Sheng-Ao; Liu, Jingao; Huang, Jian; Xiao, Yan; Chu, Zhu-Yin; Zhao, Xin-Miao; Tang, Limei

    2017-02-01

    The zinc (Zn) stable isotope system has great potential for tracing planetary formation and differentiation processes due to its chalcophile, lithophile and moderately volatile character. As an initial approach, the terrestrial mantle, and by inference, the bulk silicate Earth (BSE), have previously been suggested to have an average δ66Zn value of ∼+0.28‰ (relative to JMC 3-0749L) primarily based on oceanic basalts. Nevertheless, data for mantle peridotites are relatively scarce and it remains unclear whether Zn isotopes are fractionated during mantle melting. To address this issue, we report high-precision (±0.04‰; 2SD) Zn isotope data for well-characterized peridotites (n = 47) from cratonic and orogenic settings, as well as their mineral separates. Basalts including mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) were also measured to avoid inter-laboratory bias. The MORB analyzed have homogeneous δ66Zn values of +0.28 ± 0.03‰ (here and throughout the text, errors are given as 2SD), similar to those of OIB obtained in this study and in the literature (+0.31 ± 0.09‰). Excluding the metasomatized peridotites that exhibit a wide δ66Zn range of -0.44‰ to +0.42‰, the non-metasomatized peridotites have relatively uniform δ66Zn value of +0.18 ± 0.06‰, which is lighter than both MORB and OIB. This difference suggests a small but detectable Zn isotope fractionation (∼0.1‰) during mantle partial melting. The magnitude of inter-mineral fractionation between olivine and pyroxene is, on average, close to zero, but spinels are always isotopically heavier than coexisting olivines (Δ66ZnSpl-Ol = +0.12 ± 0.07‰) due to the stiffer Zn-O bonds in spinel than silicate minerals (Ol, Opx and Cpx). Zinc concentrations in spinels are 11-88 times higher than those in silicate minerals, and our modelling suggests that spinel consumption during mantle melting plays a key role in generating high Zn concentrations and heavy Zn isotopic

  12. A Fourier transform infrared trace gas and isotope analyser for atmospheric applications

    Directory of Open Access Journals (Sweden)

    D. W. T. Griffith

    2012-10-01

    Full Text Available Concern in recent decades about human impacts on Earth's climate has led to the need for improved and expanded measurement capabilities of greenhouse gases in the atmosphere. In this paper we describe in detail an in situ trace gas analyser based on Fourier Transform Infrared (FTIR spectroscopy that is capable of simultaneous and continuous measurements of carbon dioxide (CO2, methane (CH4, carbon monoxide (CO, nitrous oxide (N2O and 13C in CO2 in air with high precision. High accuracy is established by reference to measurements of standard reference gases. Stable water isotopes can also be measured in undried airstreams. The analyser is automated and allows unattended operation with minimal operator intervention. Precision and accuracy meet and exceed the compatibility targets set by the World Meteorological Organisation – Global Atmosphere Watch for baseline measurements in the unpolluted troposphere for all species except 13C in CO2. <br>> The analyser is mobile and well suited to fixed sites, tower measurements, mobile platforms and campaign-based measurements. The isotopic specificity of the optically-based technique and analysis allows its application in isotopic tracer experiments, for example in tracing variations of 13C in CO2 and 15N in N2O. We review a number of applications illustrating use of the analyser in clean air monitoring, micrometeorological flux and tower measurements, mobile measurements on a train, and soil flux chamber measurements.

  13. Isotope fractionation of cadmium in lunar material

    Science.gov (United States)

    Schediwy, S.; Rosman, K. J. R.; de Laeter, J. R.

    2006-03-01

    The double spike technique has been used to measure the isotope fractionation and elemental abundance of Cd in nine lunar samples, the Brownfield meteorite and the Columbia River Basalt BCR-1, by thermal ionisation mass spectrometry. Lunar soil samples give a tightly grouped set of positive isotope fractionation values of between + 0.42% and + 0.50% per mass unit. Positive isotope fractionation implies that the heavy isotopes are enhanced with respect to those of the Laboratory Standard. A vesicular mare basalt gave zero isotope fractionation, indicating that the Cd isotopic composition of the Moon is identical to that of the Earth. A sample of orange glass from the Taurus-Littrow region gave a negative isotope fractionation of - 0.23 ± 0.06% per mass unit, presumably as a result of redeposition of Cd from the Cd-rich vapour cloud associated with volcanism. Cadmium is by far the heaviest element to show isotope fractionation effects in lunar samples. The volatile nature of Cd is of importance in explaining these isotope fractionation results. Although a number of mechanisms have been postulated to be the cause of isotope fractionation of certain elements in lunar soils, we believe that the most likely mechanisms are ion and particle bombardment of the lunar surface.

  14. Anthropogenic lead isotopes in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, K.J.R.; Chisholm, W. [Curtin Univ. of Technology, Bentley (Australia); Boutron, C.F. [Laboratoire de Glaciologie et Geophysique de l`Environnement du CNRS, St. Martin d`Heres (France)]|[Domaine Universitaire, Grenoble (France); Candelone, J.P. [Laboratoire de Glaciologie et Geophysique de l`Environnement du CNRS, St. Martin d`Heres (France); Patterson, C.C. [California Institute of Technology, Pasadena, CA (United States)

    1994-12-01

    The authors present results from the first Pb isotopic study of the sources of lead in snow samples from the Antarctic. Samples of recent snow fields were compared with measurements of samples taken from deep cores, and they reveal that recent snows show pronounced influence of anthropogenic sources. These results are independent of geochemical arguments based on influences of Al, Na, or SO{sub 4}.

  15. Comparative isotope ecology of African great apes.

    Science.gov (United States)

    Oelze, Vicky M; Fahy, Geraldine; Hohmann, Gottfried; Robbins, Martha M; Leinert, Vera; Lee, Kevin; Eshuis, Henk; Seiler, Nicole; Wessling, Erin G; Head, Josephine; Boesch, Christophe; Kühl, Hjalmar S

    2016-12-01

    The isotope ecology of great apes is a useful reference for palaeodietary reconstructions in fossil hominins. As extant apes live in C3-dominated habitats, variation in isotope signatures is assumed to be low compared to hominoids exploiting C4-plant resources. However, isotopic differences between sites and between and within individuals are poorly understood due to the lack of vegetation baseline data. In this comparative study, we included all species of free-ranging African great apes (Pan troglodytes, Pan paniscus, Gorilla sp.). First, we explore differences in isotope baselines across different habitats and whether isotopic signatures in apes can be related to feeding niches (faunivory and folivory). Secondly, we illustrate how stable isotopic variations within African ape populations compare to other extant and extinct primates and discuss possible implications for dietary flexibility. Using 701 carbon and nitrogen isotope data points resulting from 148 sectioned hair samples and an additional collection of 189 fruit samples, we compare six different great ape sites. We investigate the relationship between vegetation baselines and climatic variables, and subsequently correct great ape isotope data to a standardized plant baseline from the respective sites. We obtained temporal isotopic profiles of individual animals by sectioning hair along its growth trajectory. Isotopic signatures of great apes differed between sites, mainly as vegetation isotope baselines were correlated with site-specific climatic conditions. We show that controlling for plant isotopic characteristics at a given site is essential for faunal data interpretation. While accounting for plant baseline effects, we found distinct isotopic profiles for each great ape population. Based on evidence from habituated groups and sympatric great ape species, these differences could possibly be related to faunivory and folivory. Dietary flexibility in apes varied, but temporal variation was overall

  16. WWW Table of Radioactive Isotopes

    Science.gov (United States)

    Firestone, R. B.; Ekstrom, L. P.; Chu, S. Y. F.

    1999-10-01

    An electronic sequel to the Table of Radioactive Isotopes (John Wiley, 1986) is being developed for use on the WWW. Updated adopted and decay data from the Evaluated Nuclear Structure Decay File (ENSDF) and other sources have been combined and edited. Decay scheme normalizations are revised when necessary. Gamma-ray and alpha-particle energies can be searched interactively by energy or parent half-life, mass, and atomic or neutron number. Summary data including half-lives, Q-values, production mode(s), genetic feedings, and a list of references published since the last full evaluation are available. Users can display energy or intensity ordered tables of gamma-rays, K and L x-rays, alpha-particles, and beta endpoints. Spectra of betas and bremsstrahlung, and Auger/conversion electrons can be viewed with an interactive JAVA applet. Decay schemes can be displayed with the JAVA version of Isotope Explorer 3.0. The URL for the Table of Radioactive Isotopes is http://nucleardata.nuclear.lu.se/nucleardata/toi/.

  17. Synthesis and single crystal growth of perovskite semiconductor CsPbBr3

    Science.gov (United States)

    Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Chen, Zheng; He, Jianle; Zhang, Sen; Chen, Cheng; Luo, Wei

    2018-02-01

    As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has attracted significant attention in recent years. The direct band gap semiconductor CsPbBr3 has a wide band gap of 2.25 eV and high average atomic number (Cs: 55, Pb: 82 and Br: 35), which meet most of the requirements for detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response. However, the growth of large volume CsPbBr3 single crystals remains a challenge. In this paper, the synthesis of CsPbBr3 polycrystalline powders by a chemical co-precipitation method was investigated and the optimum synthesis conditions were obtained. A large CsPbBr3 single crystal of 8 mm diameter and 60 mm length was obtained by a creative electronic dynamic gradient (EDG) method. X-ray diffraction (XRD) patterns and X-ray rocking curve showed that the CsPbBr3 crystal preferentially oriented in the (1 1 0) direction and had a low dislocation density and small residual stress in the crystal. The IR and UV-Vis transmittance and temperature-dependent photoluminescence (PL) spectra showed the crystal had a good basic optical performance. The almost linear current-voltage (I-V) curves implied good ohmic contact between the electrodes and crystal surfaces. The resistivity of the crystal was calculated 109-1010 Ω cm. The above results showed that the quality of the obtained crystal had met the demand of optoelectronic applications.

  18. Dielectric properties of a CsPbBr3 quantum dot solution in the terahertz region.

    Science.gov (United States)

    Yang, Dongsheng; Cheng, Xiangai; Liu, Yu; Shen, Chao; Xu, Zhongjie; Zheng, Xin; Jiang, Tian

    2017-04-01

    In recent years, CsPbBr3 quantum dots (QDs) have attracted much attention due to their bright prospects in solar cell studies. Dielectric properties are important for the fabrication of optoelectronic devices. Here, the dielectric properties of a CsPbBr3 QD solution are investigated between 0.1 and 2.0 THz by terahertz time-domain spectroscopy. The measured frequency-dependent transmitted ratio is found to decrease from 0.96 to 0.80 in this range. By comparing different concentrations of the QD solution, the frequency-averaged absorption is linearly increased with the increase in QD concentration. After that, the frequency-dependent dielectric constant, including the complex refractive index, complex dielectric constant, and conductivity, is extracted by Fourier transform of the time-domain spectrum. An effective medium approach method is adopted to extract the complex dielectric constant of a CsPbBr3 QD inclusion, and a slight peak around 0.4 THz is found in the imaginary part of the dielectric constant. The result of Drude-Lorentz fitting shows that the phonon plays a dominant role in the dielectric properties of a CsPbBr3 QD solution. Moreover, the THz response of a CsPbBr3 QD is found to be unchanged when the test is conducted under illumination. We attribute this phenomenon to the discrete energy level of excitons in CsPbBr3 QDs due to quantum confinement, and design a comparative experiment to validate it. This study is significant for its deeper insight into the dielectric properties of CsPbBr3 QDs, and thus is helpful through its applications in optoelectronics.

  19. Isotope labeling of proteins in insect cells.

    Science.gov (United States)

    Skora, Lukasz; Shrestha, Binesh; Gossert, Alvar D

    2015-01-01

    Protein targets of contemporary research are often membrane proteins, multiprotein complexes, secreted proteins, or other proteins of human origin. These are difficult to express in the standard expression host used for most nuclear magnetic resonance (NMR) studies, Escherichia coli. Insect cells represent an attractive alternative, since they have become a well-established expression system and simple solutions have been developed for generation of viruses to efficiently introduce the target protein DNA into cells. Insect cells enable production of a larger fraction of the human proteome in a properly folded way than bacteria, as insect cells have a very similar set of cytosolic chaperones and a closely related secretory pathway. Here, the limited and defined glycosylation pattern that insect cells produce is an advantage for structural biology studies. For these reasons, insect cells have been established as the most widely used eukaryotic expression host for crystallographic studies. In the past decade, significant advancements have enabled amino acid type-specific as well as uniform isotope labeling of proteins in insect cells, turning them into an attractive expression host for NMR studies. © 2015 Elsevier Inc. All rights reserved.

  20. Image segmentation for uranium isotopic analysis by SIMS: Combined adaptive thresholding and marker controlled watershed approach

    Energy Technology Data Exchange (ETDEWEB)

    Willingham, David G.; Naes, Benjamin E.; Heasler, Patrick G.; Zimmer, Mindy M.; Barrett, Christopher A.; Addleman, Raymond S.

    2016-05-31

    A novel approach to particle identification and particle isotope ratio determination has been developed for nuclear safeguard applications. This particle search approach combines an adaptive thresholding algorithm and marker-controlled watershed segmentation (MCWS) transform, which improves the secondary ion mass spectrometry (SIMS) isotopic analysis of uranium containing particle populations for nuclear safeguards applications. The Niblack assisted MCWS approach (a.k.a. SEEKER) developed for this work has improved the identification of isotopically unique uranium particles under conditions that have historically presented significant challenges for SIMS image data processing techniques. Particles obtained from five NIST uranium certified reference materials (CRM U129A, U015, U150, U500 and U850) were successfully identified in regions of SIMS image data 1) where a high variability in image intensity existed, 2) where particles were touching or were in close proximity to one another and/or 3) where the magnitude of ion signal for a given region was count limited. Analysis of the isotopic distributions of uranium containing particles identified by SEEKER showed four distinct, accurately identified 235U enrichment distributions, corresponding to the NIST certified 235U/238U isotope ratios for CRM U129A/U015 (not statistically differentiated), U150, U500 and U850. Additionally, comparison of the minor uranium isotope (234U, 235U and 236U) atom percent values verified that, even in the absence of high precision isotope ratio measurements, SEEKER could be used to segment isotopically unique uranium particles from SIMS image data. Although demonstrated specifically for SIMS analysis of uranium containing particles for nuclear safeguards, SEEKER has application in addressing a broad set of image processing challenges.

  1. Influence of sea ice cover on evaporation and water vapour isotopic composition in the Arctic

    Science.gov (United States)

    Bonne, Jean-Louis; Werner, Martin; Meyer, Hanno; Kipfstuhl, Sepp; Rabe, Benjamin; Behrens, Melanie; Schönicke, Lutz; Steen-Larsen, Hans Christian

    2017-04-01

    Since July 2015, water stable isotopes (HDO and H218O) have been measured at two Arctic facilities: during the summer on board of the research vessel Polarstern, and year-round at the Siberian coastal site of Samoylov, situated in the Lena delta (N 72°22', E 126°29'), close to the Laptev Sea. In both places, the isotopic composition of water vapour is analysed continuously in surface air. Additional isotopic measurements are performed on a daily basis in ocean surface water samples taken on Polarstern and on an event basis from precipitation sampled in Samoylov. The two Polarstern summer campaigns cover a large region of the western Artic Ocean, including a one-month campaign in the central and eastern Arctic crossing the North Pole in September 2015, with very cold conditions (up to -20°C). Combining ocean and atmospheric observations from Polarstern allows an evaluation of local surface water evaporation and its isotopic fingerprint relative to the oceanic and meteorological conditions as well as the partial sea ice cover. In the central and eastern Arctic, a large area of complete sea ice cover also revealed a strong impact on the advected moisture above the ice cap under very cold conditions. A first year of Siberian observations at Samoylov depicted a large seasonal variability, with extremely dry and isotopically depleted winter values. Contrasted seasonal isotopic regimes might be utilized for identifying moisture sources changes in the region, such as ocean surface closure by sea ice, or freezing of the Lena River. Besides documenting the present meteorology and changes in the Arctic, our measurements will contribute to a better interpretation of regional paleoclimate records based on water isotopes and to the evaluation of climate models in the Arctic. A first model-data comparison of our measurements with simulation results by the isotope-enabled atmospheric general circulation model ECHAM5-wiso have revealed relevant model biases in the Arctic realm.

  2. Using multiple isotopes to understand the source of ingredients used in golden beverages

    Science.gov (United States)

    Wynn, J. G.

    2011-12-01

    Traditionally, beer contains 4 simple ingredients: water, barley, hops and yeast. Each of these ingredients used in the brewing process contributes some combination of a number of "traditional" stable isotopes (i.e., isotopes of H, C, O, N and S) to the final product. As an educational exercise in an "Analytical Techniques in Geology" course, a group of students analyzed the isotopic composition of the gas, liquid and solid phases of a variety of beer samples collected from throughout the world (including other beverages). The hydrogen and oxygen isotopic composition of the water followed closely the isotopic composition of local meteoric water at the source of the brewery, although there is a systematic offset from the global meteoric water line that may be due to the effects of CO2-H2O equilibration. The carbon isotopic composition of the CO2 reflected that of the solid residue (the source of carbon used as a fermentation substrate), but may potentially be modified by addition of gas-phase CO2 from an inorganic source. The carbon isotopic composition of the solid residue similarly tracks that of the fermentation substrate, and may indicate some alcohol fermented from added sugars in some cases. The nitrogen isotopic composition of the solid residue was relatively constant, and may track the source of nitrogen in the barley, hops and yeast. Each of the analytical methods used is a relatively standard technique used in geological applications, making this a "fun" exercise for those involved, and gives the students hands-on experience with a variety of analytes from a non-traditional sample material.

  3. Chlorine isotope behavior during prograde metamorphism of sedimentary rocks

    Science.gov (United States)

    Selverstone, Jane; Sharp, Zachary D.

    2015-05-01

    Chlorine stable isotope compositions of two sedimentary sequences and their metamorphic equivalents were measured in order to study fractionation effects during prograde metamorphism and devolatilization. Protoliths (n = 25) were collected from a 50 m section of Triassic fluvial and playa-lake strata and Jurassic (Liassic) marine black shales in a well-characterized quarry. Low greenschist to middle amphibolite facies equivalents (n > 80) were collected from the Glarus Alps, Urseren Zone, and Lucomagno region. Bulk δ37Cl values are constant within individual sedimentary layers, but vary from -2.0 to + 2.4 ‰ in Triassic rocks and from -3.0 to 0‰ in the black shales. Dolomitic and gypsiferous samples have positive δ37Cl values, but marls and shales are isotopically negative. Bulk Cl contents show only small declines during the earliest stages of metamorphism. Metamorphic equivalents of the Triassic and Liassic protoliths record the same overall ranges in δ37Cl as their protoliths. Samples with highly correlated bulk compositions but different metamorphic grade show no statistically significant difference in δ37Cl. These data lead to the following conclusions: (1) Terrestrial and marine sedimentary rocks display large primary heterogeneities in chlorine isotope composition. As a result, an unambiguous "sedimentary signature" does not exist in the chlorine stable isotope system. (2) No isotopic fractionation is discernable during metamorphic devolatilization, even at low temperatures. Alpine-style metamorphism thus has little to no effect on bulk chlorine isotopic compositions, despite significant devolatilization. (3) Cl is largely retained in the rocks during devolatilization, contrary to the normally assumed hydrophilic behavior of chlorine. Continuous release of mixed-volatile C-O-H fluids likely affected Cl partitioning between fluid and minerals and allowed chlorine to remain in the rocks. (4) There is no evidence for fluid communication across (meta

  4. Proposed Closing Order : St. Vincent

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The attached letter directed to Secretary Morton from the Florida Chapter of The Nature Conservancy recommends the establishment of a Secretarial closing order on...

  5. Pollution hazard closes neutrino lab

    CERN Multimedia

    Jones, Nicola

    2003-01-01

    "A leading astrophysics laboratory in Italy has closed down all but one of its experiments over concerns that toxic polluants could leak form the underground lab into the local water supply" (0.5 page)

  6. Social thermoregulation in close relationships

    OpenAIRE

    Wagemans, Fieke

    2014-01-01

    This poster presents data from Wagemans, F. M. A. & IJzerman, H. (2014, February). Social thermoregulation in close relationships. Poster presented at the annual meeting of the Society for Personality and Social Psychology, Austin, USA. 

  7. The stable isotope ecology of Pan in Uganda and beyond.

    Science.gov (United States)

    Loudon, James E; Sandberg, Paul A; Wrangham, Richard W; Fahey, Babette; Sponheimer, Matt

    2016-10-01

    Stable isotope analysis has long been used to study the dietary ecology of living and fossil primates, and there has been increasing interest in using stable isotopes to study primate habitat use and anthropogenic impacts on non-human primates. Here, we examine the stable carbon and nitrogen isotope compositions of chimpanzees (Pan troglodytes) from seven communities in Uganda across a continuum of habitat structure (closed to more open) and access to anthropogenic resources (no reliance to heavy reliance). In general, the hair δ(13) C, but not δ(15) N, values of these communities vary depending on forest structure and degree of anthropogenic influence. When integrated with previously published hair δ(13) C and δ(15) N values for Pan, it is apparent that modern "savanna" and "forest" Pan form discrete clusters in carbon and nitrogen isotope space, although there are exceptions probably relating to microhabitat specialization. The combined dataset also reveals that Pan δ(13) C values (but not δ(15) N values) are inversely related to rainfall (r(2)  = 0.62). We converted Pan hair δ(13) C values to enamel equivalents and made comparisons to the fossil hominoids Sivapithecus sp., Gigantopithecus blacki, Ardipithecus ramidus, and Australopithecus anamensis. The δ(13) C values of the fossil hominins Ar. ramidus and Au. anamensis do not cluster with the δ(13) C values of modern Pan in "forest" habitats, or with fossil hominoids that are believed to have inhabited forests. Am. J. Primatol. 78:1070-1085, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Radiogenic isotopes of arc lavas constrain uplift of the Andes

    Science.gov (United States)

    Scott, Erin; Allen, Mark B.; Macpherson, Colin; McCaffrey, Ken; Davidson, Jon; Saville, Christopher

    2017-04-01

    Orogenic plateaux are an ultimate expression of continental tectonics, but the timings and mechanisms of their formation are far from understood. The elevation history of the Andes is of particular importance for climatic reconstructions, as they pose the only barrier to atmospheric circulation in the Southern Hemisphere. Many varied techniques have been utilized over the last two decades to constrain Andean Plateau (AP) surface uplift. Two conflicting schools of thought are prominent: (1) recent, rapid rise since 10-6 Ma (Late Miocene), and (2) slow, continued uplift from 40 Ma. We propose a new, independent, approach to constrain AP surface uplift through time. By comparing isotopic compositions of Andean Quaternary arc lavas to present day crustal thickness and topography, we show that Sr and Nd isotopes are effective discriminants for the modern extent of the AP. As previously described, these isotopic systems are sensitive to crustal contamination, which in turn relates to crustal thickness, and, via isostasy, to regional surface elevation. We apply this relationship to a new compilation of published, age corrected, isotopic compositions of arc lavas, to constrain the surface uplift history of the Andes from the Jurassic to present day. Our results are consistent with significant AP surface uplift beginning in the Mid to Late Paleogene. We show that by 23 Ma, the AP was established at close to its modern elevations between at least 16-28 deg. S, thereby predating models for Late Miocene surface uplift. Between 23-10 Ma, surface uplift propagated south of 28 deg. S by a further 400 km. Our model has implications for understanding magma plumbing systems in regions of thick, wide crust, especially other orogenic plateaux.

  9. Isotopic fractionation during soil uptake of atmospheric hydrogen

    Directory of Open Access Journals (Sweden)

    A. Rice

    2011-03-01

    Full Text Available Soil uptake of atmospheric hydrogen (H2 and the associated hydrogen isotope effect were studied using soil chambers in a Western Washington second-growth coniferous forest. Chamber studies were conducted during both winter and summer seasons to account for large natural variability in soil moisture content (4–50% and temperature (6–22 °C. H2 deposition velocities were found to range from 0.01–0.06 cm s−1 with an average of 0.033 ± 0.008 cm s−1 (95% confidence interval. Consistent with prior studies, deposition velocities were correlated with soil moisture below 20% soil moisture content during the summer season. During winter, there was considerable variability observed in deposition velocity that was not closely related to soil moisture. The hydrogen kinetic isotope effect with H2 uptake was found to range from −24‰ to −109‰. Aggregate analysis of experimental data results in an average KIE of −57 ± 5‰ (95% CI. Some of the variability in KIE can be explained by larger isotope effects at lower (<10% and higher (>30% soil moisture contents. The measured KIE was also found to be correlated with deposition velocity, with smaller isotope effects occurring at higher deposition velocities. If correct, these findings will have an impact on the interpretation of atmospheric measurements and modeling of δD of H2.

  10. Isotope Geochemistry for Comparative Planetology of Exoplanets

    Science.gov (United States)

    Mandt, K. E.; Atreya, S.; Luspay-Kuti, A.; Mousis, O.; Simon, A.; Hofstadter, M. D.

    2017-01-01

    Isotope geochemistry has played a critical role in understanding processes at work in and the history of solar system bodies. Application of these techniques to exoplanets would be revolutionary and would allow comparative planetology with the formation and evolution of exoplanet systems. The roadmap for comparative planetology of the origins and workings of exoplanets involves isotopic geochemistry efforts in three areas: (1) technology development to expand observations of the isotopic composition of solar system bodies and expand observations to isotopic composition of exoplanet atmospheres; (2) theoretical modeling of how isotopes fractionate and the role they play in evolution of exoplanetary systems, atmospheres, surfaces and interiors; and (3) laboratory studies to constrain isotopic fractionation due to processes at work throughout the solar system.

  11. Linearity for Ca2+-Doped CeBr3 Scintillating Materials

    Energy Technology Data Exchange (ETDEWEB)

    Guss, Paul [NSTec

    2014-02-03

    The Remote Sensing Laboratory (RSL) developed an aliovalently calcium-doped cerium tribromide (CeBr3:Ca2+) crystal with 3.2% resolution. RSL completed a crystal assessment, and Sandia National Laboratories calculated the predictive performance and physical characteristics using proven density functional theory (DFT) formalism. Results are reported for the work done to map the detector performance, characteristics, calcium doping concentration, and crystal strength. Preliminary scintillation measurements for this aliovalently calcium-doped CeBr3 scintillator exhibit a slight blue shift in fluorescence emission at 371 nm excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using DFT within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated. Specifically, we report excellent linearity with the aliovalently calcium-doped CeBr3 crystal. Proportionality of light yield is one area of performance in which Ce-doped and Ce-based lanthanide halides excel. Maintaining proportionality is key to producing a strong, high-performance scintillator. Relative light yield proportionality was measured for both doped and undoped samples of CeBr3 to ensure no loss in performance was incurred during doping. The light output and proportionality, however, appear to be similar to CeBr3. There was a reduced yield at low energy. Relative light yield proportionality measurements suggest that dopants do not significantly affect proportionality at higher energies. RSL completed additional testing and evaluation of the new crystal and assessed benchmark spectroscopy measurements. Results, which present energy resolution as a function of energy, are summarized. Typical spectroscopy results using a 137Cs radiation source are shown

  12. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    Science.gov (United States)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    ratios showed distinct differences between the closed CANDU primary coolant system and radiopharmaceutical production releases. According to the concept proposed by Kalinowski and Pistner (2006), the relationship between different isotopic activity ratios based on three or four radioxenon isotopes was plotted in a log-log diagram for source characterisation (civil vs. nuclear test). The multiple isotopic activity ratios were distributed in three distinct areas: HC atmospheric monitoring ratios extended to far left; the CANDU primary coolant system ratios lay in the middle; and 99Mo stack monitoring ratios for ANSTO and CRL were located on the right. The closed CANDU primary coolant has the lowest logarithmic mean ratio that represents the nuclear power reactor operation. The HC atmospheric monitoring exhibited a broad range of ratios spreading over several orders of magnitude. In contrast, the ANSTO and CRL stack emissions showed the smallest range of ratios but the results indicate at least two processes involved in the 99Mo productions. Overall, most measurements were found to be shifted towards the reactor domain. The hypothesis is that this is due to an accumulation of the isotope 131mXe in the stack or atmospheric background as it has the longest half-life and extra 131mXe emissions from the decay of 131I. The contribution of older 131mXe to a fresh release shifts the ratio of 133mXe/131mXe to the left. It was also very interesting to note that there were some situations where isotopic ratios from 99Mo production emissions fell within the nuclear test domain. This is due to operational variability, such as shorter target irradiation times. Martin B. Kalinowski and Christoph Pistner, (2006), Isotopic signature of atmospheric xenon released from light water reactors, Journal of Environmental Radioactivity, 88, 215-235.

  13. CsPbBr{sub 3} nanocrystal saturable absorber for mode-locking ytterbium fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yan; Li, Yue; Xu, Jianqiu; Tang, Yulong, E-mail: yulong@sjtu.edu.cn [Key Laboratory for Laser Plasmas (MOE), Department of Physics and Astronomy, Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240 (China); Hu, Zhiping; Tang, Xiaosheng [Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2016-06-27

    Cesium lead halide perovskite nanocrystals (CsPbX{sub 3}, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr{sub 3} nanocrystal films and characterize their physical properties. Broadband linear absorption from ∼0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr{sub 3} saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr{sub 3} liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm{sup 2}, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ∼216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ∼1076 nm. This work shows that CsPbBr{sub 3} films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

  14. A2BR adenosine receptor modulates sweet taste in circumvallate taste buds.

    Directory of Open Access Journals (Sweden)

    Shinji Kataoka

    Full Text Available In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3 on taste nerves as well as metabotropic (P2Y purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate, but not anterior (fungiform, palate taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields.

  15. A2BR Adenosine Receptor Modulates Sweet Taste in Circumvallate Taste Buds

    Science.gov (United States)

    Yang, Dan; Shultz, Nicole; Vandenbeuch, Aurelie; Ravid, Katya; Kinnamon, Sue C.; Finger, Thomas E.

    2012-01-01

    In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3) on taste nerves as well as metabotropic (P2Y) purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR) is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate), but not anterior (fungiform, palate) taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields. PMID:22253866

  16. Intrinsic Lead Ion Emissions in Zero-Dimensional Cs4PbBr6 Nanocrystals

    KAUST Repository

    Yin, Jun

    2017-11-07

    We investigate the intrinsic lead ion (Pb2+) emissions in zero-dimensional (0D) perovskite nanocrystals (NCs) using a combination of experimental and theoretical approaches. The temperature-dependent photoluminescence experiments for both “nonemissive” (highly suppressed green emission) and emissive (bright green emission) Cs4PbBr6 NCs show a splitting of emission spectra into high- and low-energy transitions in the ultraviolet (UV) spectral range. In the nonemissive case, we attribute the high-energy UV emission at approximately 350 nm to the allowed optical transition of 3P1 to 1S0 in Pb2+ ions and the low-energy UV emission at approximately 400 nm to the charge-transfer state involved in the 0D NC host lattice (D-state). In the emissive Cs4PbBr6 NCs, in addition to the broad UV emission, we demonstrate that energy transfer occurs from Pb2+ ions to green luminescent centers. The optical phonon modes in Cs4PbBr6 NCs can be assigned to both Pb–Br stretching and rocking motions from density functional theory calculations. Our results address the origin of the dual broadband Pb2+ ion emissions observed in Cs4PbBr6 NCs and provide insights into the mechanism of ionic exciton–optical phonon interactions in these 0D perovskites.

  17. Structure of ^69Br and the rp-process in X-ray bursts

    Science.gov (United States)

    Nesaraja, Caroline; Smith, Michael

    2010-02-01

    The long (35.5 sec.) positron decay lifetime of ^68Se, coupled with the low estimated probability of proton capture into ^69Br, make ^68Se a waiting point in the rp-process powering explosions in X-ray binaries. The thermonuclear reaction flow in X-ray bursts (XRB) depends sensitively on the properties of ^69Br, especially whether or not the ground state is proton bound [1]. Recent studies of the mass of ^68Se and the decay of ^69Br prompt a reassessment of the ^69Br properties relevant for rp-process burning in XRB. In our current project to evaluate the structure of nuclei with mass 69, we will focus on ^69Br. Our assessment, which will be included in the ENSDF database at the U.S. National Nuclear Data Center, will be used to generate a new reaction rate for proton capture on ^68Se, and subsequently for new X-ray burst nucleosynthesis calculations. [4pt] [1] H.Schatz et al., Phys. Rep. 294, 167 (1988) )

  18. Stratospheric BrO abundance measured by a balloon-borne submillimeterwave radiometer

    Directory of Open Access Journals (Sweden)

    R. A. Stachnik

    2013-03-01

    Full Text Available Measurements of mixing ratio profiles of stratospheric bromine monoxide (BrO were made using observations of BrO rotational line emission at 650.179 GHz by a balloon-borne SIS (superconductor-insulator-superconductor submillimeterwave heterodyne limb sounder (SLS. The balloon was launched from Ft. Sumner, New Mexico (34° N on 22 September 2011. Peak mid-day BrO abundance varied from 16 ± 2 ppt at 34 km to 6 ± 4 ppt at 16 km. Corresponding estimates of total inorganic bromine (Bry, derived from BrO vmr (volume mixing ratio using a photochemical box model, were 21 ± 3 ppt and 11 ± 5 ppt, respectively. Inferred Bry abundance exceeds that attributable solely to decomposition of long-lived methyl bromide and other halons, and is consistent with a contribution from bromine-containing very short lived substances, BryVSLS, of 4 ppt to 8 ppt. These results for BrO and Bry were compared with, and found to be in good agreement with, those of other recent balloon-borne and satellite instruments.

  19. Synthesis and characterization of Ag/AgBrO{sub 3} photocatalyst with high photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin, 300387 (China); Li, Tongtong [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin, 300387 (China); Zhang, Shujuan [College of Science, Tianjin University of Science & Technology, Tianjin, 300457 (China)

    2016-10-01

    A new Ag/AgBrO{sub 3} photocatalyst was prepared by mixing aqueous solutions of AgNO{sub 3} and NaBrO{sub 3}. The catalyst’s structure and performance were investigated with X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The UV–vis absorption spectrum of Ag/AgBrO{sub 3} exhibits a band gap of 3.97 eV. The results show that the Ag/AgBrO{sub 3} semiconductor can be excited by ultraviolet–visible light. The photodegradation of Rhodamine B displayed much higher photocatalytic activity than that of N-doped TiO{sub 2} under the same experimental conditions. Moreover, ·OH and ·O{sub 2}{sup −} generated in the photocatalysis played a key role of the photodegradation of Rhodamine B. - Highlights: • Ag/AgBrO{sub 3} with higher photodegradation ability was synthesized. • ·OH and ·O{sub 2}{sup −} radicals were the main active species in the oxidation of RhB. • The possible reaction mechanism was discussed in details.

  20. CsPbBr3 nanocrystal saturable absorber for mode-locking ytterbium fiber laser

    Science.gov (United States)

    Zhou, Yan; Hu, Zhiping; Li, Yue; Xu, Jianqiu; Tang, Xiaosheng; Tang, Yulong

    2016-06-01

    Cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr3 nanocrystal films and characterize their physical properties. Broadband linear absorption from ˜0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr3 saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr3 liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm2, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ˜216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ˜1076 nm. This work shows that CsPbBr3 films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

  1. XeBr excilamp based on a non-toxic component mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kelman, V A; Shpenik, Yu O; Zhmenyak, Yu V, E-mail: mironkle@rambler.ru [Institute of Electron Physics, National Academy of Sciences of Ukraine, Universitetska 21, 88017 Uzhgorod (Ukraine)

    2011-06-29

    This paper presents the results of experimental studies on obtaining UV luminescence of XeBr* molecules at the excitation of a non-toxic Xe-CsBr gas-vapour mixture by a longitudinal pulse-periodic discharge. Effective UV emission yield of the exciplex XeBr* molecules (spectral maximum at 282 nm) is observed within a wide range of excitation conditions. The spectral distribution in the UV emission under the optimal excitation conditions does not differ essentially from that in other XeBr excilamps based on toxic components. The emission of the B {yields} X band of the XeBr* molecules provides the main contribution to the total power of the discharge UV emission. The determined average power of the UV emission for the experimental discharge tube is 12 W at an efficiency of 1%. Spectral, power-related and time-dependent parameters of the laboratory excilamp are presented for a wide range of excitation parameters. A new mechanism of exciplex molecule formation at the excitation of a rare gas/alkali halide vapour mixture is discussed.

  2. Photostriction of CH3NH3PbBr3 Perovskite Crystals

    KAUST Repository

    Wei, Tzu-Chiao

    2017-07-17

    Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

  3. Photostriction of CH3 NH3 PbBr3 Perovskite Crystals.

    Science.gov (United States)

    Wei, Tzu-Chiao; Wang, Hsin-Ping; Li, Ting-You; Lin, Chun-Ho; Hsieh, Ying-Hui; Chu, Ying-Hao; He, Jr-Hau

    2017-09-01

    Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Expression of BAFF and BR3 in patients with systemic lupus erythematosus

    Directory of Open Access Journals (Sweden)

    J.H. Duan

    2016-03-01

    Full Text Available The objective of this study was to examine the relationship between the expression of B cell activating factor (BAFF and BAFF receptor in patients with disease activity of systemic lupus erythematosus (SLE. Real-time RT-PCR was used to examine BAFF mRNA expression in peripheral blood monocytes of active and stable SLE patients and healthy controls. The percentage of BAFF receptor 3 (BR3 on B lymphocytes was measured by flow cytometry. Soluble BAFF levels in serum were assayed by ELISA. Microalbumin levels were assayed by an automatic immune analysis machine. BAFF mRNA and soluble BAFF levels were highest in the active SLE group, followed by the stable SLE group, and controls (P<0.01. The percentage of BR3 on B lymphocytes was downregulated in the active SLE group compared with the stable SLE group and controls (P<0.01. BAFF mRNA levels and soluble BAFF levels were higher in patients who were positive for proteinuria than in those who were negative (P<0.01. The percentage of BR3 on B lymphocytes was lower in patients who were positive for proteinuria than in those who were negative (P<0.01. The BAFF/BR3 axis may be over-activated in SLE patients. BAFF and BR3 levels may be useful parameters for evaluating treatment.

  5. Intrinsic ferromagnetism and quantum anomalous Hall effect in a CoBr2 monolayer.

    Science.gov (United States)

    Chen, Peng; Zou, Jin-Yu; Liu, Bang-Gui

    2017-05-31

    The electronic, magnetic, and topological properties of a CoBr2 monolayer are studied in the framework of density-functional theory (DFT) combined with tight-binding (TB) modeling in terms of the Wannier basis. Our DFT investigation and Monte Carlo simulation show that there exists intrinsic two-dimensional ferromagnetism in the CoBr2 monolayer, thanks to the large out-of-plane magnetocrystalline anisotropic energy. Our further study indicates that the spin-orbit coupling makes it become a topologically nontrivial insulator with a quantum anomalous Hall effect and topological Chern number [script C] = 4 and its edge states can be manipulated by changing the width of its nanoribbons and applying strains. The CoBr2 monolayer can be exfoliated from the layered CoBr2 bulk material because its exfoliation energy is between those of graphene and the MoS2 monolayer and it is dynamically stable. These results make us believe that the CoBr2 monolayer can make a promising spintronic material for future high-performance devices.

  6. Fast-neutron induced background in LaBr{sub 3}:Ce detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kiener, J., E-mail: Jurgen.Kiener@csnsm.in2p3.fr [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Tatischeff, V.; Deloncle, I. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Séréville, N. de [Institut de Physique Nucléaire d' Orsay, CNRS-IN2P3 and Université Paris-Sud, 91406 Orsay (France); Laurent, P. [CEA/IRFU Service d' Astrophysique, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Laboratoire Astroparticules et Cosmologie (APC), 10, rue A. Domon et L. Duquet, 75205 Paris (France); Blondel, C. [Laboratoire AIM, CEA/IRFU, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Chabot, M. [Institut de Physique Nucléaire d' Orsay, CNRS-IN2P3 and Université Paris-Sud, 91406 Orsay (France); Chipaux, R. [CEA/DMS/IRFU/SEDI, CEA Saclay, 91191 Gif sur Yvette (France); Coc, A. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); Dubos, S. [Laboratoire AIM, CEA/IRFU, Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette (France); Gostojic, A. [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3 et Université Paris-Sud, 91405 Campus Orsay (France); and others

    2015-10-21

    The response of a scintillation detector with a cylindrical 1.5-in. LaBr{sub 3}:Ce crystal to incident neutrons has been measured in the energy range E{sub n} = 2–12 MeV. Neutrons were produced by proton irradiation of a Li target at E{sub p} = 5–14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr{sub 3}:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced γ rays emitted by the LaBr{sub 3}:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr{sub 3}:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr{sub 3}:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range E{sub n} = 0.5–10 MeV.

  7. Constraints on the vital effect in coccolithophore and dinoflagellate calcite by oxygen isotopic modification of seawater

    Science.gov (United States)

    Hermoso, Michaël; Horner, Tristan J.; Minoletti, Fabrice; Rickaby, Rosalind E. M.

    2014-09-01

    In this study, we show that there are independent controls of 18O/16O and 13C/12C fractionation in coccolithophore and dinoflagellate calcite due to the contrasting kinetics of each isotope system. We demonstrate that the direction and magnitude of the oxygen isotope fractionation with respect to equilibrium is related to the balance between calcification rate and the replenishment of the internal pool of dissolved inorganic carbon (DIC). As such, in fast growing cells, such as those of Emiliania huxleyi and Gephyrocapsa oceanica (forming the so-called ;heavy group;), calcification of the internal carbon pool occurs faster than complete isotopic re-adjustment of the internal DIC pool with H2O molecules. Hence, coccoliths reflect the heavy oxygen isotope signature of the CO2 overprinting the whole DIC pool. Conversely, in large and slow growing cells, such as Coccolithus pelagicus ssp. braarudii, complete re-equilibration is achieved due to limited influx of CO2 leading to coccoliths that are precipitated in conditions close to isotopic equilibrium (;equilibrium group;). Species exhibiting the most negative oxygen isotope composition, such as Calcidiscus leptoporus (;light group;), precipitate coccolith under increased pH in the coccolith vesicle, as previously documented by the ;carbonate ion effect;. We suggest that, for the carbon isotope system, any observed deviation from isotopic equilibrium is only ;apparent;, as the carbon isotopic composition in coccolith calcite is controlled by a Rayleigh fractionation originating from preferential incorporation of 12C into organic matter. Therefore, species with low PIC/POC ratios as E. huxleyi and G. oceanica are shifted towards positive carbon isotope values as a result of predominant carbon fixation into the organic matter. By contrast, cells with higher PIC/POC as C. braarudii and C. leptoporus maintain, to some extent, the original negative isotopic composition of the CO2. The calcareous dinoflagellate

  8. Isotope techniques in hydrology and sedimentology; Tecnicas isotopicas em hidrologia e sedimentologia

    Energy Technology Data Exchange (ETDEWEB)

    Bomtempo, Virgilio Lopardi [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil). Coordenacao de Desenvolvimento Cientifico e Tecnologico. Supervisao de Tecnicas Nucleares

    1999-11-01

    Water is the foundation of all life on Earth. Although two thirds of the terrestrial surface are covered by water (estimated volume is 1.5 billion cubic meters), just 2% of this total are fresh water, most of it locked in glaciers, ice caps and in deep groundwater reservoirs. Only 2,000 cubic kilometers are estimated to be available for consumption. Water resources have become more and more scarce, and the utilization becomes increasingly costly, due to the impact caused by over-exploitation and by diversified fronts of pollution. Specialists have been working in the development and in the application of several techniques to face this problem and to produce sustainable solutions. Isotope techniques represent a group of widespread tools that have been used along many years, and have become outstanding in hydrological investigation. This paper introduces a comprehensive review of the isotope techniques, taking into account environmental isotopes (stable and radioactive), artificial tracers and the use of radioactive sealed sources. Potentialities and limitations, future perspectives, as well as risks and benefits are also discussed. (author) 6 refs., 1 tab.; e-mail: vlb at urano.cdtn.br

  9. Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements

    Directory of Open Access Journals (Sweden)

    H. Sihler

    2012-11-01

    Full Text Available During polar spring, halogen radicals like bromine monoxide (BrO play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2. Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution.

  10. Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC

    Directory of Open Access Journals (Sweden)

    S. Choi

    2012-02-01

    Full Text Available We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative transfer model and stratospheric column BrO from a photochemical simulation. We conduct a comprehensive comparison of satellite-derived tropospheric BrO column to aircraft in-situ observations of BrO and related species. The aircraft profiles reveal that tropospheric BrO, when present during April 2008, was distributed over a broad range of altitudes rather than being confined to the planetary boundary layer (PBL. Perturbations to the total column resulting from tropospheric BrO are the same magnitude as perturbations due to longitudinal variations in the stratospheric component, so proper accounting of the stratospheric signal is essential for accurate determination of satellite-derived tropospheric BrO. We find reasonably good agreement between satellite-derived tropospheric BrO and columns found using aircraft in-situ BrO profiles, particularly when satellite radiances were obtained over bright surfaces (albedo >0.7, for solar zenith angle <80° and clear sky conditions. The rapid activation of BrO due to surface processes (the bromine explosion is apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low surface pressure, strong wind, and high PBL height are associated with an observed BrO activation event, supporting the notion of bromine activation by high winds over snow.

  11. Compound-specific hydrogen isotope analysis of fluorine-, chlorine-, bromine- and iodine-bearing organics using gas chromatography-chromium-based high-temperature conversion (Cr/HTC) isotope ratio mass spectrometry.

    Science.gov (United States)

    Renpenning, Julian; Schimmelmann, Arndt; Gehre, Matthias

    2017-07-15

    The conventional high-temperature conversion (HTC) approach towards hydrogen compound-specific isotope analysis (CSIA) of halogen-bearing (F, Cl, Br, I) organics suffers from incomplete H2 yields and associated hydrogen isotope fractionation due to generation of HF, HCl, HBr, and HI byproducts. Moreover, the traditional off-line combustion of highly halogenated compounds results in incomplete recovery of water as an intermediary compound for hydrogen isotope ratio mass spectrometry (IRMS), and hence also leads to isotope fractionation. This study presents an optimized chromium-based high-temperature conversion (Cr/HTC) approach for hydrogen CSIA of various fluorinated, chlorinated, brominated and iodinated organic compounds. The Cr/HTC approach is fast, economical, and not affected by low H2 yields and associated isotope fractionation. The performance of the modified gas chromatography/chromium-based high-temperature conversion (GC-Cr/HTC) system was monitored and optimized using an ion trap mass spectrometer. Quantitative conversion of organic hydrogen into H2 analyte gas was achieved for all halogen-bearing compounds. The corresponding accuracy of CSIA was validated using (i) manual dual-inlet (DI)-IRMS after off-line conversion into H2 , and (ii) elemental analyzer (EA)-Cr/HTC-IRMS (on-line conversion). The overall hydrogen isotope analysis of F-, Cl-, Br- and I-bearing organics via GC-Cr/HTC-IRMS achieved a precision σ ≤ 3 mUr and an accuracy within ±5 mUr along the VSMOW-SLAP scale compared with the measured isotope compositions resulting from both validation methods, off-line and on-line. The same analytical performance as for single-compound GC-Cr/HTC-IRMS was achieved compound-specifically for mixtures of halogenated organics following GC separation to baseline resolution. GC-Cr/HTC technology can be implemented in existing analytical equipment using commercially available materials to provide a versatile tool for hydrogen CSIA of halogenated and non

  12. A Measurement of the Relative Branching Ratio $BR(B^- \\to D^0 K^-) / BR(B^- \\to D^0 \\pi^-)$ in Three $D^0$ Decay Modes

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Hung-Chung [Univ. of California, Berkeley, CA (United States)

    2011-01-01

    Using 1.3 fb-1 of data from p$\\bar{p}$ collisions at √s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we have measured the relative branching ratio $BR(B^- \\to D^0 K^-) / BR(B^- \\to D^0 \\pi^-)$ in Three $D^0$ and its charge conjugate in the D0 flavor decay mode D$0\\atop{f}$ → K-π+ and the CP-even decay modes D0 → K-K+ and D0 → π-π+

  13. High temperature infrared spectra and vibrational analysis of GaBr 3 and AlBr 3NH 3 in the vapour phase

    Science.gov (United States)

    Rytter, E.; Einarsrud, M.-A.; Sjøgren, Carl E.

    The i.r. vapour spectra of monomeric and dimeric gallium bromide and of tribromoammine aluminium at 523-723 K were recorded in the 50-1800 and 2300-3500 cm -1 regions. An evacuable nickel cell equipped with a type IIa diamond window and sealed with a gold O-ring was employed. With the exception of the dimer ring puckering, all i.r. active gallium bromide fundamentals were observed. The monomer spectra were found to be consistent with a planar D3 h structure. All i.r. active modes of tribromoammine aluminium, except the symmetric NH stretch and AlBr 3 rock vibrations, were assigned. The interpretation was supported by normal coordinate analyses. An attempt was made to correlate the valence stretching force constants of several MX 3, M 2X 6, M 2X -7 (M = Al, Ga; X  Cl, Br, I) compounds with the MX bond lengths.

  14. Iron isotopic fractionation in industrial emissions and urban aerosols.

    Science.gov (United States)

    Flament, Pascal; Mattielli, Nadine; Aimoz, Laure; Choël, Marie; Deboudt, Karine; de Jong, Jeroen; Rimetz-Planchon, Juliette; Weis, Dominique

    2008-12-01

    A study on tropospheric aerosols involving Fe particles with an industrial origin is tackled here. Aerosols were collected at the largest exhausts of a major European steel metallurgy plant and around its near urban environment. A combination of bulk and individual particle analysis performed by SEM-EDX provides the chemical composition of Fe-bearing aerosols emitted within the factory process (hematite, magnetite and agglomerates of these oxides with sylvite (KCl), calcite (CaCO(3)) and graphite carbon). Fe isotopic compositions of those emissions fall within the range (0.08 per thousandclose urban area, 5km away from the steel plant, individual particle analysis of collected aerosols presents, in addition to the industrial particle type, aluminosilicates and related natural particles (gypsum, quartz, calcite and reacted sea salt). The Fe isotopic composition (delta(56)Fe=0.14+/-0.11 per thousand) measured in the close urban environment of the steel metallurgy plant appears coherent with an external mixing of industrial and continental Fe-containing tropospheric aerosols, as evidenced by individual particle chemical analysis. Our isotopic data provide a first estimation of an anthropogenic source term as part of the study of photochemically promoted dissolution processes and related Fe fractionations in tropospheric aerosols.

  15. Isotopic Compositions of the Elements 1997

    Science.gov (United States)

    Rosman, K. J. R.; Taylor, P. D. P.

    1998-11-01

    The Commission's Subcommittee for the Isotopic Composition of the Elements has carried out its biennial review of isotopic compositions, as determined by mass spectrometry and other relevant methods. This involves a critical evaluation of the published literature, element by element, and forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry presented here. New guidelines have been used to arrive at the uncertainties on the isotopic abundances and there are numerous changes to the table since it was last published in 1991. Atomic Weights calculated from this table are consistent with Ar(E) values listed in the Table of Standard Atomic Weights 1997.

  16. Stable isotope labeling methods for DNA.

    Science.gov (United States)

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A

    2016-08-01

    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Isotopic investigation of an Australian island environment

    Energy Technology Data Exchange (ETDEWEB)

    Groecke, D.R. [Australian National Univ., Canberra, ACT (Australia). Research School of Earth Sciences; Bocherens, H. [Paris-6 Univ., 75 (France)

    1996-12-31

    Collagen has been extracted from fossil bones of mega-fauna herbivores from Kangaroo Island, South Australia (Australia). Carbon and nitrogen stable isotope analyses of collagen have provided an insight into the palaeo-ecology of these late Pleistocene herbivores. In comparison with continental fossil localities in South Australia, the island herbivores have elevated nitrogen isotopic abundances. Carbon isotopic abundances suggest that browsing species had a mixed diet of grasses and leaves on the island, in contrast to the specimens from mainland Australia. Possible causes regarding elevated nitrogen isotope abundances and dietary shifts in this palaeo-ecology are discussed. (authors). 24 refs., 2 figs., 1 tab.

  18. Impact of glacial activity on the weathering of Hf isotopes - Observations from Southwest Greenland

    Science.gov (United States)

    Rickli, Jörg; Hindshaw, Ruth S.; Leuthold, Julien; Wadham, Jemma L.; Burton, Kevin W.; Vance, Derek

    2017-10-01

    Data for the modern oceans and their authigenic precipitates suggest incongruent release of hafnium (Hf) isotopes by chemical weathering of the continents. The fact that weathering during recent glacial periods is associated with more congruent release of Hf isotopes has led to the hypothesis that the incongruency may be controlled by retention of unradiogenic Hf by zircons, and that glacial grinding enhances release of Hf from zircons. Here we study the relationship between glacial weathering processes and Hf isotope compositions released to rivers fed by land-terminating glaciers of the Greenland Ice Sheet, as well as neighbouring non-glacial streams. The weathered source rocks in the studied area mostly consist of gneisses, but also include amphibolites of the same age (1.9 Ga). Hafnium and neodymium isotope compositions in catchment sediments and in the riverine suspended load are consistent with a predominantly gneissic source containing variable trace amounts of zircon and different abundances of hornblende, garnet and titanite. Glacially sourced rivers and non-glacial streams fed by precipitation and lakes show very unradiogenic Nd isotopic compositions, in a narrow range (ɛNd= -42.8 to -37.9). Hafnium isotopes, on the other hand, are much more radiogenic and variable, with ɛHf between -18.3 and -0.9 in glacial rivers, and even more radiogenic values of +15.8 to +46.3 in non-glacial streams. Although relatively unradiogenic Hf is released by glacial weathering, glacial rivers actually fall close to the seawater array in Hf-Nd isotope space and are not distinctly unradiogenic. Based on their abundance in rocks and sediments and their isotope compositions, different minerals contribute to the radiogenic Hf in solution with a decreasing relevance from garnet to titanite, hornblende and apatite. Neodymium isotopes preclude a much stronger representation of titanite, hornblende and apatite in solution, such as might result from differences in dissolution rates

  19. Strontium isotope fractionation during strontianite (SrCO3) dissolution, precipitation and at equilibrium

    Science.gov (United States)

    Mavromatis, Vasileios; Harrison, Anna L.; Eisenhauer, Anton; Dietzel, Martin

    2017-12-01

    In this study we examine the behavior of stable Sr isotopes between strontianite [SrCO3] and reactive fluid during mineral dissolution, precipitation, and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 0.01 M NaCl solutions wherein the pH was adjusted by bubbling of a water saturated gas phase of pure CO2 or atmospheric air. The equilibrium Sr isotope fractionation between strontianite and fluid after dissolution of the solid under 1 atm CO2 atmosphere was estimated as Δ88/86SrSrCO3-fluid = δ88/86Sr SrCO3 - δ88/86Srfluid = -0.05 ± 0.01‰. On the other hand, during strontianite precipitation, an enrichment of the fluid phase in 88Sr, the heavy isotopomer, was observed. The evolution of the δ88/86Srfluid during strontianite precipitation can be modeled using a Rayleigh distillation approach and the estimated, kinetically driven, fractionation factor αSrCO3-fluid between solid and fluid is calculated to be 0.99985 ± 0.00003 corresponding to Δ88/86SrSrCO3-fluid = -0.15‰. The obtained results further support that under chemical equilibrium conditions between solid and fluid a continuous exchange of isotopes occurs until the system approaches isotopic equilibrium. This isotopic exchange is not limited to the outer surface layer of the strontianite crystal, but extends to ∼7-8 unit cells below the crystal surface. The behavior of Sr isotopes in this study is in excellent agreement with the concept of dynamic equilibrium and it suggests that the time needed for achievement of chemical equilibrium is generally shorter compared to that for isotopic equilibrium. Thus it is suggested that in natural Sr-bearing carbonates an isotopic change may still occur close to thermodynamic equilibrium, despite no observable change in aqueous elemental concentrations. As such, a secondary and ongoing change of Sr isotope signals in carbonate minerals caused by isotopic re-equilibration with fluids has to be considered in order to use Sr

  20. Lifetimes of excited states in neutron-rich Xe isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ilieva, Stoyanka; Kroell, Thorsten [Institut fuer Kernphysik, TU Darmstadt (Germany); Collaboration: EXILL-FATIMA-Collaboration

    2016-07-01

    The EXILL and FATIMA campaign at ILL, Grenoble is the first prompt-fission γ-ray spectroscopy experiment performed with a mixed array of Ge detectors (EXILL) and fast LaBr{sub 3}(Ce) scintillators (FATIMA). The lifetimes of excited states, populated by neutron-induced fission of {sup 235}U and {sup 241}Pu targets, were directly measured. The high-resolution EXILL detector gives us the possibility to identify the nuclides of interest among the large amount of produced fission fragments. Using the generalized centroid difference method to analyse the data from FATIMA we could measure lifetimes down to ∼ 10 ps. The lifetime of an excited state is a direct measure for the strength (collectivity) of a transition. The properties of the excited states in even-even nuclei can be largely described by quadrupole and octupole degrees of freedom. This contribution will present the current status of the analysis for the neutron-rich even-even {sup 138,140,142}Xe isotopes which lie in the vicinity of the double shell closure Z=50 and N=82. Through the direct lifetime measurement we aim to study the evolution of quadrupole and octupole collectivity above {sup 132}Sn.

  1. The reaction ensemble method for the computer simulation of chemical and phase equilibria. II. The Br2+Cl2+BrCl system

    Science.gov (United States)

    Lísal, Martin; Nezbeda, Ivo; Smith, William R.

    1999-05-01

    The reaction ensemble Monte Carlo (REMC) method [W. R. Smith and B. Třı´ska, J. Chem. Phys. 100, 3019 (1994)] is used to study combined reaction and vapor-liquid equilibrium of the Br2+Cl2+BrCl system. The substances are modeled as nonpolar and dipolar two-site Lennard-Jones molecules with Lorentz-Berthelot mixing rules for unlike atoms. No parameters were fitted to any mixture properties in our calculations. The simulated data are compared with experimental results, and with previous simulation data for the mixture obtained by an indirect semigrand ensemble approach. The REMC method efficiently calculates the complete phase compositions, whereas only a limited subset is available experimentally. The agreement of the simulations with experiment is good. In the course of this work, we used the Gibbs ensemble Monte Carlo method (which may be regarded as a special case of the REMC method) to calculate the vapor-liquid equilibrium properties of pure BrCl; since this compound is chemically unstable, such data is experimentally inaccessible.

  2. Pyomelanin is produced by Shewanella algae BrY and affected by exogenous iron.

    Science.gov (United States)

    Turick, Charles E; Caccavo, Frank; Tisa, Louis S

    2008-04-01

    Melanin production by Shewanella algae BrY occurred during late- and (or) post-exponential growth in lactate basal salts liquid medium supplemented with tyrosine or phenylalanine. The antioxidant ascorbate inhibited melanin production but not production of the melanin precursor homogentisic acid. In the absence of ascorbate, melanin production was inhibited by the 4-hydroxyphenylpyruvate dioxygenase inhibitor sulcotrione and by concentrations of Fe >or= 0.38 mmol L(-1). These data support the hypothesis that pigment production by S. algae BrY was a result of the conversion of tyrosine or phenylalanine to homogentisic acid, which was excreted, auto-oxidized, and self-polymerized to form pyomelanin. Pyomelanin production by S. algae BrY may play an important role in the biogeochemical cycling of Fe in the environment.

  3. Localized optical absorption in Cs{sub 4}PbBr{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, S.; Amaya, K.; Saito, T. [Research Center for Development of Far-Infrared Region, Fukui University, Bunkyo, Fukui (Japan)

    2002-03-04

    The fundamental optical absorption of Cs{sub 4}PbBr{sub 6} crystals, which are built up of nearly regular Pb{sup 2+}(Br{sup -}){sub 6} octahedra mutually bound by Cs{sup +} ions, exhibits novel features: despite the crystalline entity of Cs{sub 4}PbBr{sub 6}, it shows oscillator-like absorption peaks and a wide window just above the first peak. The Cs{sup +} ions prevent the Pb{sup 2+} 6s and 6p states from taking part in the construction of extended states. These states form a set of localized states confined to within respective octahedra, similar to the case of isolated Pb{sup 2+} ions doped in face-centred cubic alkali halide crystals. (author)

  4. Spectral studies related to dissociation of HBr, HCl and BrO

    Science.gov (United States)

    Ginter, M. L.

    1986-01-01

    Concern over halogen catalyzed decomposition of O3 in the upper atmosphere has generated need for data on the atomic and molecular species X, HX and XO (where X is Cl and Br). Of special importance are Cl produced from freon decomposition and Cl and Br produced from natural processes and from other industrial and agricultural chemicals. Basic spectral data is provided on HCl, HBr, and BrO necessary to detect specific states and energy levels, to enable detailed modeling of the processes involving molecular dissociation, ionization, etc., and to help evaluate field experiments to check the validity of model calculations for these species in the upper atmosphere. Results contained in four published papers and two major spectral compilations are summarized together with other results obtained.

  5. A measurement of the semileptonic branching ratio BR(b-baryon $\\rightarrow p l\\overline{\

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Boix, G; Casado, M P; Chmeissani, M; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Graugès-Pous, E; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bright-Thomas, P G; Casper, David William; Cattaneo, M; Cerutti, F; Ciulli, V; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Lehraus, Ivan; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Teubert, F; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Badaud, F; Chazelle, G; Deschamps, O; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Boccali, T; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Lynch, J G; Negus, P; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Buchmüller, O L; Dhamotharan, S; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Williams, M D; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Buck, P G; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Williams, M I; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Antonelli, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Mannert, C; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Rizzo, G; Sanguinetti, G; Sciabà, A; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Konstantinidis, N P; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Reeve, J; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; Gao, Y; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G

    1998-01-01

    Inclusive pi^+/-, K^+/- (p,pbar) production is investigated using data recorded by the ALEPH detector between 1992 and 1994. The momentum spectra and multiplicities are measured separately in Z -->bbar, Z-->ccbar and Z-->uubar,ddbar,ssbar decays. The number of protons found in b-hadron decays is used to estimate the fraction of b-baryons in b-events to be (10.2 +/- 0.7 +/- 2.7)%. From an additional study of proton-lepton correlations in b events the branching ratio Br(b-baryon --> plnuX) = (4.63 +/- 0.72 +/- 0.98)% is obtained. The ratio Br(b-baryon --> plnuX)/ Br(b-baryon --> pX) is found to be 0.080 +/- 0.012 +/- 0.014.

  6. Energy-Dependent Peak Shifts in LaBr3 Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Stinnett, Jacob [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vo, Duc Ta [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-28

    Significant peak shifts were noted in a laboratory LaBr3 detector. To investigate these issues, three LaBr3 detectors were used to collect spectra of Cs-137 with either Co-57, Co-60, or no secondary source included. The cobalt source locations were varied to control the deadtime, while the Cs-137 source remained in a fixed position relative to the detectors. Each setup was measured with a 0.8 μs and a 3.2 μs shaping time. All spectra were measured for a 100 second live time. All three LaBr3 detectors were experienced peak-shifting as a function of deadtime and gamma-ray energies. However, the first detector (Detector A, described below) had significantly more severe peakshifting which was also affected by the shaping time.

  7. Inflation in a closed universe

    Science.gov (United States)

    Ratra, Bharat

    2017-11-01

    To derive a power spectrum for energy density inhomogeneities in a closed universe, we study a spatially-closed inflation-modified hot big bang model whose evolutionary history is divided into three epochs: an early slowly-rolling scalar field inflation epoch and the usual radiation and nonrelativistic matter epochs. (For our purposes it is not necessary to consider a final dark energy dominated epoch.) We derive general solutions of the relativistic linear perturbation equations in each epoch. The constants of integration in the inflation epoch solutions are determined from de Sitter invariant quantum-mechanical initial conditions in the Lorentzian section of the inflating closed de Sitter space derived from Hawking's prescription that the quantum state of the universe only include field configurations that are regular on the Euclidean (de Sitter) sphere section. The constants of integration in the radiation and matter epoch solutions are determined from joining conditions derived by requiring that the linear perturbation equations remain nonsingular at the transitions between epochs. The matter epoch power spectrum of gauge-invariant energy density inhomogeneities is not a power law, and depends on spatial wave number in the way expected for a generalization to the closed model of the standard flat-space scale-invariant power spectrum. The power spectrum we derive appears to differ from a number of other closed inflation model power spectra derived assuming different (presumably non de Sitter invariant) initial conditions.

  8. Program plan for the Brayton isotope power system. Phase I. design, fabrication and test of the Brayon isotope power system

    Energy Technology Data Exchange (ETDEWEB)

    1975-10-22

    This program plan covers Phase I of an overall program for the development of a 500 to 2000 W/sub e/ (EOM), 7-year life, power system for space vehicles. The system uses a closed Brayton dynamic system to convert energy from an isotope heat source at a net efficiency greater than 25 percent. This first phase, a 35-months effort, is for the conceptual design of a 1300 W/sub e/, 450 lb flight system and the design, fabrication, and test of a ground demonstration system. The flight system will use, for the baseline design, two of the multihundred-watt (MHW) heat sources being developed for the ERDA by the General Electric Company. The Ground Demonstration System will simulate, as closely as possible, the Brayton Isotope Power Flight System and will utilize components and technology being developed by NASA for the Mini-Brayton rotating unit, recuperator and heat source assembly, respectively. The Ground Demonstration System includes a performance test and a 1000-hour endurance test.

  9. BrEPS 2.0: Optimization of sequence pattern prediction for enzyme annotation.

    Directory of Open Access Journals (Sweden)

    Christian-Alexander Dudek

    Full Text Available The prediction of gene functions is crucial for a large number of different life science areas. Faster high throughput sequencing techniques generate more and larger datasets. The manual annotation by classical wet-lab experiments is not suitable for these large amounts of data. We showed earlier that the automatic sequence pattern-based BrEPS protocol, based on manually curated sequences, can be used for the prediction of enzymatic functions of genes. The growing sequence databases provide the opportunity for more reliable patterns, but are also a challenge for the implementation of automatic protocols. We reimplemented and optimized the BrEPS pattern generation to be applicable for larger datasets in an acceptable timescale. Primary improvement of the new BrEPS protocol is the enhanced data selection step. Manually curated annotations from Swiss-Prot are used as reliable source for function prediction of enzymes observed on protein level. The pool of sequences is extended by highly similar sequences from TrEMBL and SwissProt. This allows us to restrict the selection of Swiss-Prot entries, without losing the diversity of sequences needed to generate significant patterns. Additionally, a supporting pattern type was introduced by extending the patterns at semi-conserved positions with highly similar amino acids. Extended patterns have an increased complexity, increasing the chance to match more sequences, without losing the essential structural information of the pattern. To enhance the usability of the database, we introduced enzyme function prediction based on consensus EC numbers and IUBMB enzyme nomenclature. BrEPS is part of the Braunschweig Enzyme Database (BRENDA and is available on a completely redesigned website and as download. The database can be downloaded and used with the BrEPScmd command line tool for large scale sequence analysis. The BrEPS website and downloads for the database creation tool, command line tool and database are

  10. Novel Ge-Ga-Te-CsBr glass system with ultrahigh resolvability of halide.

    Science.gov (United States)

    Cheng, Ci; Wang, Xunsi; Xu, Tiefeng; Zhu, Qingde; Sun, Lihong; Pan, Zhanghao; Nie, Qiuhua; Zhang, Peiqing; Wu, Yuehao; Dai, Shixun; Shen, Xiang; Zhang, Xianghua

    2015-11-05

    CO2 molecule, one of the main molecules to create new life, should be probed accurately to detect the existence of life in exoplanets. The primary signature of CO2 molecule is approximately 15 μm, and traditional S- and Se-based glass fibers are unsuitable. Thus, Te-based glass is the only ideal candidate glass for far-infrared detection. In this study, a new kind of Te-based chalcohalide glass system was discovered with relatively stable and large optical band gap. A traditional melt-quenching method was adopted to prepare a series of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glass samples. Experiment results indicate that the glass-forming ability and thermal properties of glass samples were improved when CsBr was added in the host of Ge-Ga-Te glass. Ge-Ga-Te glass could remarkably dissolve CsBr content as much as 85 at.%, which is the highest halide content in all reports for Te-based chalcohalide glasses. Moreover, ΔT values of these glass samples were all above 100 °C. The glass sample (Ge15Ga10Te75)65 (CsBr)35 with ΔT of 119 °C was the largest, which was 7 °C larger than that of Ge15Ga10Te75 host glass. The infrared transmission spectra of these glasses show that the far-infrared cut-off wavelengths of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses were all beyond 25 μm. In conclusion, (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses are potential materials for far-infrared optical application. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Observation of Enhanced Hole Extraction in Br Concentration Gradient Perovskite Materials.

    Science.gov (United States)

    Kim, Min-Cheol; Kim, Byeong Jo; Son, Dae-Yong; Park, Nam-Gyu; Jung, Hyun Suk; Choi, Mansoo

    2016-09-14

    Enhancing hole extraction inside the perovskite layer is the key factor for boosting photovoltaic performance. Realization of halide concentration gradient perovskite materials has been expected to exhibit rapid hole extraction due to the precise bandgap tuning. Moreover, a formation of Br-rich region on the tri-iodide perovskite layer is expected to enhance moisture stability without a loss of current density. However, conventional synthetic techniques of perovskite materials such as the solution process have not achieved the realization of halide concentration gradient perovskite materials. In this report, we demonstrate the fabrication of Br concentration gradient mixed halide perovskite materials using a novel and facile halide conversion method based on vaporized hydrobromic acid. Accelerated hole extraction and enhanced lifetime due to Br gradient was verified by observing photoluminescence properties. Through the combination of secondary ion mass spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy analysis, the diffusion behavior of Br ions in perovskite materials was investigated. The Br-gradient was found to be eventually converted into a homogeneous mixed halide layer after undergoing an intermixing process. Br-substituted perovskite solar cells exhibited a power conversion efficiency of 18.94% due to an increase in open circuit voltage from 1.08 to 1.11 V and an advance in fill-factor from 0.71 to 0.74. Long-term stability was also dramatically enhanced after the conversion process, i.e., the power conversion efficiency of the post-treated device has remained over 97% of the initial value under high humid conditions (40-90%) without any encapsulation for 4 weeks.

  12. Temperature dependence of the rate constant and product channels for the BrO + ClO reaction

    OpenAIRE

    Hills, AJ; Cicerone, RJ; Calvert, JG; Birks, JW

    1988-01-01

    We have measured the rate constant for the reactions BrO + ClO → Br + OClO (6a), BrO + ClO → Br + Cl + O 2 (6b), and BrO + ClO → BrCl + O 2 (6c) over the temperature range 241-408 K and found k 6 = (8.2 ± 1.0) × 10 -12 cm 3 molecule -1 s independent of temperature. Measurement of the individual product branching ratios yielded values for channels 6a, 6b, and 6c equal to 0.55 ± 0.10, 0.45 ± 0.10, and < 0.02, respectively. Measurements of ozone in the stratosphere over Antarctica have s...

  13. Characterization of extreme ultraviolet laser ablation mass spectrometry for actinide trace analysis and nanoscale isotopic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Green, Tyler; Kuznetsov, Ilya; Willingham, David; Naes, Benjamin E.; Eiden, Gregory C.; Zhu, Zihua; Chao, W.; Rocca, Jorge J.; Menoni, Carmen S.; Duffin, Andrew M.

    2017-01-01

    The purpose of this research was to characterize Extreme Ultraviolet Time-of-Flight (EUV TOF) Laser Ablation Mass Spectrometry for high spatial resolution elemental and isotopic analysis. We compare EUV TOF results with Secondary Ionization Mass Spectrometry (SIMS) to orient the EUV TOF method within the overall field of analytical mass spectrometry. Using the well-characterized NIST 61x glasses, we show that the EUV ionization approach produces relatively few molecular ion interferences in comparison to TOF SIMS. We demonstrate that the ratio of element ion to element oxide ion is adjustable with EUV laser pulse energy and that the EUV TOF instrument has a sample utilization efficiency of 0.014%. The EUV TOF system also achieves a lateral resolution of 80 nm and we demonstrate this lateral resolution with isotopic imaging of closely spaced particles or uranium isotopic standard materials.

  14. Closed suction drainage versus closed simple drainage in the ...

    African Journals Online (AJOL)

    Objective: To compare the outcome of modified radical mastectomy wounds managed by closed wound drainage with suction and without suction. Methods: A prospective randomized trial was conducted at the University College Hospital Ibadan and University of Nigeria Teaching Hospital Enugu, Nigeria. Fifty women who ...

  15. Crafting Creative Nonfiction: From Close Reading to Close Writing

    Science.gov (United States)

    Dollins, Cynthia A.

    2016-01-01

    A process writing project in a third-grade classroom explored the idea of using nonfiction mentor texts to assist students in writing their own creative informational texts about animals. By looking at author craft and structure during close reading activities with nonfiction Twin Texts, students were taught how to emulate these techniques in…

  16. The Mechanism Underlying the Brückner Effect Studied with an Automated, High-Resolution, Continuously Scanning Brückner Device.

    Science.gov (United States)

    de Groot, Matthijs J; van der Helm, Frans C T; Simonsz, Huib J

    2015-01-01

    When an eye is illuminated by a light coaxial with the observing eye or camera, the light is reflected by the back of the eye and a red reflex will be observed through the pupil. The intensity of this red reflex varies with the angle of eccentric gaze. The red reflex darkens as the eye fixates at the light source. Brückner described this principle in 1962. Although this effect has been used as a screening test for strabismus ever since, the mechanism that causes this effect is only partly known. None of the current explanations are accepted as conclusively proven. We developed an automated, high-resolution, continuously scanning Brückner device to study the mechanisms underlying the Brückner effect. The right eyes of 6 subjects, students aged 22-31 years, were measured. A subject sat in front of a camera at a distance of about 0.75 m. The luminance of the red fundus reflex and the eye movements were measured continuously while the subject followed a fixation target that moved in two dimensions. Eye movement was also recorded objectively and in the analysis this was used in addition to the position of the fixation target. The eyes were illuminated coaxially using an infrared light source and a beam splitter. By using two methods to record eye rotation and relating this to the continuously measured pupillary luminous intensity and pupillary area, we were able to construct 2-dimensional maps of pupillary luminance. All 6 subjects showed the expected general darkening of the pupil as fixation changed from eccentric fixation to foveal fixation at the center of the camera. However, there were many local fluctuations. The global minimum in pupillary luminance, the "dark spot," was often roughly circle-shaped with a radius of about 1°. The pupillary luminance kept increasing beyond 2° eccentricity. We measured the Brückner effect continuously in two dimensions. Brückner's original explanation--absorption by the macular pigment--cannot explain our findings as the

  17. Exploring the isotopic niche: isotopic variance, physiological incorporation, and the temporal dynamics of foraging

    Directory of Open Access Journals (Sweden)

    Justin Douglas Yeakel

    2016-01-01

    Full Text Available Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer's physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic `landscape' of its prey, i.e. the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contribution of a set of prey to a consumer's diet based on their respective isotopic distributions, however they are disconnected from ecological process. Here we build a mechanistic framework that links the ecological and physiological processes of an individual consumer to the isotopic distribution that describes its diet, and ultimately to the isotopic composition of its own tissues, defined as its `isotopic niche’. By coupling these processes, we systematically investigate under what conditions the isotopic niche of a consumer changes as a function of both the geometric properties of its mixing space and foraging strategies that may be static or dynamic over time. Results of our derivations reveal general insight into the conditions impacting isotopic niche width as a function of consumer specialization on prey, as well as the consumer's ability to transition between diets over time. We show analytically that moderate specialization on isotopically unique prey can serve to maximize a consumer's isotopic niche width, while temporally dynamic diets will tend to result in peak isotopic variance during dietary transitions. We demonstrate the relevance of our theoretical findings by examining a marine system composed of nine invertebrate species commonly consumed by sea otters. In general, our analytical framework highlights the complex interplay of mixing space geometry and consumer dietary behavior in driving expansion and contraction of the isotopic niche. Because this approach is established on ecological mechanism, it is well-suited for enhancing the

  18. Cierco Pb-Zn-Ag vein deposits: Isotopic and fluid inclusion evidence for formation during the mesozoic extension in the pyrenees of Spain

    Science.gov (United States)

    Johnson, C.A.; Cardellach, E.; Tritlla, J.; Hanan, B.B.

    1996-01-01

    The Cierco Pb-Zn-Ag vein deposits, located in the central Pyrenees of Spain, crosscut Paleozoic metasedimentary rocks and are in close proximity to Hercynian granodiorite dikes and plutons. Galena and sphalerite in the deposits have average ??34S values of -4.3 and -0.8 per mil (CDT), respectively. Coexisting mineral pairs give an isotopic equilibration temperature range of 89?? to 163??C which overlaps with the 112?? to 198??C range obtained from primary fluid inclusions. Coexisting quartz has a ??18O value of 19 ?? 1 per mil (VSMOW). The fluid which deposited these minerals is inferred to have had ??18OH2o and ??34SH2s values of 5 ?? 1 and -1 ?? 1 per mil, respectively. Chemical and microthermometric analyses of fluid inclusions in quartz and sphalerite indicate salinities of 3 to 29 wt percent NaCl equiv with Na+ and Ca2+ as the dominant cations in solution. The Br/Cl and I/Cl ratios differ from those characteristic of magmatic waters and pristine seawater, but show some similarity to those observed in deep ground waters in crystalline terranes, basinal brines, and evaporated seawater, Barite, which postdates the sulfides, spans isotopic ranges of 13 to 21 per mil, 10 to 15 per mil, and 0.7109 to 0.7123 for ??34S, ??18O, and 87Sr/86Sr, respectively. The three parameters are correlated providing strong evidence that the barites are products of fluid mixing. We propose that the Cierco deposits formed along an extensional fault system at the margin of a marine basin during the breakup of Pangea at some time between the Early Triassic and Early Cretaceous. Sulfide deposition corresponded to an upwelling of hydrothermal fluid from the Paleozoic basement and was limited by the amount of metals carried by the fluid. Barite deposition corresponded to the waning of upward flow and the collapse of sulfate-rich surface waters onto the retreating hydrothermal plume. Calcite precipitated late in the paragenesis as meteoric or marine waters descended into the fault system

  19. Futebol et hiérarchies urbaines au Brésil.

    Directory of Open Access Journals (Sweden)

    Hervé Théry

    2006-03-01

    Full Text Available Le football n’est pas seulement la passion nationale du Brésil, il peut être aussi un bon indicateur des hiérarchies urbaines du pays. Les classements disponibles sur le site de la fédération brésilienne de futebol peuvent être mis en rapport avec d’autres données pour vérifier la corrélation entre les performances sportives des clubs et le degré de centralité des villes où ils sont basés.

  20. Optical characterization of TlBr single crystals for radiation detection applications

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon Ho; Kim, Dong Jin; Kim, Han Soo; Lee, Seung Hee; Ha, Jang Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2016-06-15

    TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and γ-rays are of prime importance. However, there were few reports on investigating optical properties of TlBr itself for deeper understandings of this material and for making better radiation detection devices. Thus, in this paper, we report on the optical characterizations of TlBr single crystals. Spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements at RT were performed for this work. A 2-inch TlBr single crystalline ingot was grown by using the vertical Bridgman furnace. SE measurements were performed at RT within the photon energy range from 1.1 to 6.5 eV. PL measurements were performed at RT by using a home-made PL system equipped with a 266 nm-laser and a spectrometer. Dielectric responses from SE analysis were shown to be slightly different among the different samples possibly due to the different structural/optical properties. Also from the PL measurements, it was observed that the peak intensities of the middle samples were significantly higher than those of the other two samples. With the given values for permittivity of free space (ε0 = 8.854x10{sup -1}2 F·m{sup -1}), thickness (d = 1 mm), and area (A = 10x10 mm{sup 2}) of the TlBr sample, capacitances of TlBr were 6.9 pF (at hν = 3 eV) and 4.4 pF (at hν = 6 eV), respectively. SE and PL measurement and analysis were performed to characterize TlBr samples from the optical perspective. It was observed that dielectric responses of different TlBr samples were slightly different due to the different material properties. PL measurements showed that the middle sample exhibited much stronger PL emission peaks due to the better material quality. From the SE analysis, optical, dielectric constants were extracted, and calculated capacitances were in the few pF range.

  1. Observations of BrO Using Limb Scanning DOAS During the 2013 NOMADSS Campaign

    Science.gov (United States)

    Festa, J.; Stutz, J.; Tsai, J. Y.; Spolaor, M.; Zhou, X.; Ye, C.; Jaffe, D. A.; Gratz, L.; Ambrose, J. L., II; Jaegle, L.; Shah, V.; Selin, N. E.; Song, S.

    2014-12-01

    Bromine monoxide (BrO) is an important atmospheric constituent, participating in the destruction of tropospheric and stratospheric ozone and the oxidation of gaseous elemental Hg (GEM) to form reactive Hg (RM). During the Nitrogen, Oxidants, Mercury and Aerosol Distributions, Sources and Sinks (NOMADSS) campaign in the summer of 2013, our group operated a limb-scanning Differential Optical Absorption Spectroscopy (DOAS) instrument onboard the NSF/NCAR C-130 aircraft with the goal of quantifying BrO, formaldehyde (HCHO), nitrogen dioxide (NO2), and other trace gases. Here we present observations of Differential Slant Column Densities (DSCD) obtained in the limb derived using the DOAS analysis technique. A radiative transfer model (McArtim [Deutschmann et al., 2011]), constrained by in-situ measurement on the aircraft or from published literature, was utilized to simulate the DSCDs and to derive BrO mixing ratios at flight altitude. BrO mixing ratios were typically below our 2σ detection limit (ranging from 0.5 - 1 ppt) with the exception of a high altitude (~7km asl) portion of a flight over Central and West Texas (RF 6), and a marine boundary layer (~0.2km asl) flight leg off the coast of South Carolina (RF 16). Around 1.9 ± 0.25 ppt of BrO was detected for about 1.5 hours in the high altitude flight, and around 1.0 ±0.5 ppt of BrO was detected in the marine boundary layer. Several features were present in the higher altitude air-mass with detectable BrO: O3 and humidity were significantly depressed relative to other flight legs at the same altitude and large concentrations of RM were simultaneously observed. We will present possible sources for the anomalously high BrO mixing ratios in the sampled air mass and discuss the implications of our knowledge on free-tropospheric bromine chemistry and its effects on GEM oxidation.

  2. Investigation of the PGNAA using the LaBr{sub 3} scintillation detector

    Energy Technology Data Exchange (ETDEWEB)

    Favalli, A. [European Commission, Joint Research Centre, Institute for the Protection and Security of Citizen, TP800, Via E. Fermi, 21027 Ispra (Italy)], E-mail: andrea.dr.favalli@gmail.com; Mehner, H-C.; Ciriello, V.; Pedersen, B. [European Commission, Joint Research Centre, Institute for the Protection and Security of Citizen, TP800, Via E. Fermi, 21027 Ispra (Italy)

    2010-04-15

    The Joint Research Centre of the European Commission develops instrumentation for detection of hazardous materials. In relation to this a new experimental facility was constructed for research into methods applying the detection of characteristic gamma rays subsequent to neutron irradiation. This includes the detection of prompt gamma rays from neutron inelastic scattering and neutron capture. For this purpose the device employs LaBr{sub 3} scintillation detectors. The paper investigates the applicability of the LaBr{sub 3} scintillation detector to PGNAA.

  3. BR(Bs to mu+ mu-) as an electroweak precision test

    CERN Document Server

    Guadagnoli, Diego

    2013-01-01

    Using an effective-theory approach, we analyze the impact of BR(Bs to mu+ mu-) in constraining new-physics models that predict modifications of the Z-boson couplings to down-type quarks. Under motivated assumptions about the flavor structure of the effective theory, we show that the bounds presently derived from BR(Bs to mu+ mu-) on the effective Z-boson couplings are comparable (in the case of minimal flavor violation) or significantly more stringent (in the case of generic partial compositeness) with respect to those derived from observables at the Z peak.

  4. Silicon Isotopic Fractionation in a Tropical Soil-Plant System

    Science.gov (United States)

    Opfergelt, S.; Delstanche, S.; Cardinal, D.; Andre, L.; Delvaux, B.

    2006-12-01

    -0.33 (Ovs) and -0.56 permil (Yvs), close to the fractionation factor previously measured in hydroponics (-0.40 permil). The average delta29Si of phytoliths in banana plants was +0.17 permil. In the topsoil, the isotopic composition of Yvs ( 0.21 permil) was close to that of unweathered pumice (-0.20 permil). The Ovs were significantly lighter (-0.73 permil), confirming published data pointing to lighter isotopic composition with increased weathering. Heavier bulk plants at Ovs might be related to a heavier residual soil solution due to: (i) the formation of lighter clay minerals at Ovs (clay fraction: -0.94 permil) than at Yvs (-0.60 permil), and (ii) the quantitative adsorption of silica onto iron oxides (see Delstanche et al., 2006, AGU), more abundant in weathered Ovs. Our data support the view that plants can induce a strong imprint on the continental cycle of silicon, just as clay formation and possibly Si adsorption onto iron oxides can do. The quantification of Si-isotopic fractionation in the soil-plant system requires, however, further studies involving all the Si pools to achieve a comprehensive understanding of this cycle.

  5. The complex story of a simple Brønsted acid: unusual speciation of HBr in an ionic liquid medium.

    Science.gov (United States)

    Driver, Gordon W; Mutikainen, Ilpo

    2011-11-07

    Crystalline solids, co-existing in equilibrium with the 3-methyl-1H-imidazolium bromohydrogenates(I) ionic liquid, have been characterised by X-ray diffraction analysis. The Brønsted acidic, homo-conjugate [H(2)Br(3)](-) anions presented are discussed in terms of their structure and reactivity, in efforts to advance the understanding of Brønsted acidity in ionic liquid media.

  6. An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Desong, E-mail: dswang06@126.com; Zhao, Mangmang; Luo, Qingzhi; Yin, Rong; An, Jing; Li, Xueyan

    2016-04-15

    Highlights: • An efficient visible-light photocatalyst was prepared by modifying AgBr particles. • A small amount of activated carbon was used to modify AgBr particles. • The modified AgBr exhibited improved visible-light photocatalytic performances. - Abstract: An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO) and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.

  7. Cold atoms close to surfaces

    DEFF Research Database (Denmark)

    Krüger, Peter; Wildermuth, Stephan; Hofferberth, Sebastian

    2005-01-01

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold (T atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to ... be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial...

  8. Evolution of Close Binary Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  9. Selected scientific topics of the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds.

    Science.gov (United States)

    Atzrodt, Jens; Derdau, Volker

    2013-01-01

    This micro-review describes hot topics and new trends in isotope science discussed at the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds from a personal perspective. Copyright © 2013 John Wiley & Sons, Ltd.

  10. physico-chemical and stable isotopes

    African Journals Online (AJOL)

    This paper details the mineralogical, chemical and stable isotope abundances of calcrete in the Letlhakeng fossil valley. The stable isotope abundances (O and C) of calcretes yielded some values which were tested against the nature of the calcretes – pedogenic or groundwater type. The Kgalagadi (Kalahari) is a vast ...

  11. Advanced Mass Spectrometers for Hydrogen Isotope Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Chastagner, P.

    2001-08-01

    This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

  12. Dual Carbon and Nitrogen Isotope Analysis

    African Journals Online (AJOL)

    According to Hemminga & Mateo. (1996), values of carbon and nitrogen isotope ratios vary considerably between seagrass species. It might also be expected that the remaining seagrass species could have some influence on the shrimp carbon signal. Isotopic evidence for mangroves being a carbon source for shrimps ...

  13. Isotopic niches support the resource breadth hypothesis.

    Science.gov (United States)

    Rader, Jonathan A; Newsome, Seth D; Sabat, Pablo; Chesser, R Terry; Dillon, Michael E; Martínez Del Rio, Carlos

    2017-03-01

    Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges. We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology. We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology. Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  14. Isotopic niches support the resource breadth hypothesis

    Science.gov (United States)

    Rader, Jonathan A.; Newsome, Seth D.; Sabat, Pablo; Chesser, R. Terry; Dillon, Michael E.; Martinez del Rio, Carlos

    2017-01-01

    Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges.We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology.We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology.Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies.

  15. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  16. The isotopic dipole moment of HDO

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Mohallem, Jose R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, CP 702, 30123-970, Belo Horizonte, MG (Brazil)

    2007-03-14

    An adiabatic variational approximation is used to study the monodeuterated water molecule, HDO, accounting for the isotopic effect. The isotopic dipole moment, pointing from D to H, is then calculated for the first time, yielding (1.5 {+-} 0.1) x 10{sup -3} Debye, being helpful in the interpretation of experiments. (fast track communication)

  17. Environmental isotopes investigation in groundwater of Challaghatta ...

    African Journals Online (AJOL)

    Radiogenic isotopes (3H and 14C) and stable isotope (18O) together with TDS, EC and salinity of water were used to discriminate qualitative and quantitative groundwater age, probable recharge time, flow respectively in groundwater of Challaghatta valley, Bangalore. The variations between TDS and EC values of sewage ...

  18. Isotope Program Report June FY2016

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jr, Benjamin E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Egle, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    Isotope Program Monthly Highlights are briefly described. These include data on isotopes shipped, updates on equipment fabrication and testing, a potential new approach for nondestructive measurement of the amount of Cf-252 deposited on a surface, and efforts to recover and purify uranium-234 obtained from old PuBe sources.

  19. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 8. Use of Isotopes for Studying Reaction Mechanisms-Secondary Kinetic Isotope Effect. Uday Maitra J Chandrasekhar. Series Article Volume 2 Issue 8 August 1997 pp 18-25 ...

  20. Tracing thallium contamination in soils using isotopes

    Science.gov (United States)

    Vaněk, Aleš; Grösslová, Zuzana; Mihaljevič, Martin; Ettler, Vojtěch; Trubač, Jakub; Teper, Leslaw; Cabala, Jerzy; Rohovec, Jan; Penížek, Vít; Zádorová, Tereza; Pavlů, Lenka; Holubík, Ondřej; Drábek, Ondřej; Němeček, Karel; Houška, Jakub; Ash, Christopher

    2017-04-01

    We report the thallium (Tl) isotope record in moderately contaminated soils, which have been historically affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ɛ205Tl -1) naturally occurs. The results show a positive linear relationship (R2 = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ɛ205Tl 0), followed by fly ash (ɛ205Tl between -2.5 and -2.8) and volatile Tl fractions (ɛ205Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistribution, we demonstrate that Tl contamination can be traced in soils, and propose that the isotope data represent a possible tool to aid our understanding of post-depositional Tl dynamics in surface environments for the future. This research was supported by the Czech Science Foundation (grant no. 14-01866S and 17-03211S).

  1. Correction of MS data for naturally occurring isotopes in isotope labelling experiments.

    Science.gov (United States)

    Millard, Pierre; Letisse, Fabien; Sokol, Serguei; Portais, Jean-Charles

    2014-01-01

    Mass spectrometry (MS) in combination with isotope labelling experiments is widely used for investigations of metabolism and other biological processes. Quantitative applications-e.g., (13)C metabolic flux analysis-require correction of raw MS data (isotopic clusters) for the contribution of all naturally abundant isotopes. This chapter describes how to perform such correction using the software IsoCor. This flexible, user-friendly software can be used to exploit any isotopic tracer, from well-known ((13)C, (15)N, (18)O, etc.) to unusual ((57)Fe, (77)Se, etc.) isotopes. It also provides options-e.g., correction for the isotopic purity of the tracer-to improve the accuracy of quantitative isotopic studies, and allows automated correction of large datasets that can be collected with modern MS methods.

  2. Experimental studies and nuclear model calculations on proton-induced reactions on (nat)Se, (76)Se and (77)Se with particular reference to the production of the medically interesting radionuclides (76)Br and (77)Br.

    Science.gov (United States)

    Hassan, H E; Qaim, S M; Shubin, Yu; Azzam, A; Morsy, M; Coenen, H H

    2004-06-01

    Excitation functions of the reactions (nat)Se(p,x)(75,76,77,82)Br, (76)Se(p,xn)(75,76)Br, (76)Se(p,x)(75)Se and (77)Se(p,xn)(76,77)Br were measured from their respective thresholds up to 40 MeV, with particular emphasis on data for the production of the medically important radionuclides (76)Br and (77)Br. The conventional stacked-foil technique was used. The samples were prepared by a sedimentation process. Irradiations were performed using the compact cyclotron CV 28 and the injector of COSY, both at the Research Centre Jülich. In order to validate the data, nuclear model calculations were performed using the code ALICE-IPPE which is based on the preequilibrium-evaporation model. Good agreement was found between the experimental and theoretical data, except in the high-energy region where the calculated data were somewhat higher. All the measured excitation curves were compared with the data available in the literature. From the experimental data the theoretical yields of all the investigated radionuclides were calculated and plotted as a function of proton energy. The calculated yield of (77)Br from the (nat)Se(p,x)(77)Br process over the energy range E(p)=25-->15 is 72.7 MBq/microAh and from the (77)Se(p,n)(77)Br reaction over E(p)=15-->6 MeV it is 86.2 MBq/microAh. The yield of (76)Br from the (76)Se(p,n)(76)Br reaction for E(p)=15-->8 is 360.1 MBq/microAh and from the (77)Se(p,2n)(76)Br reaction for E(p)=28-->18 MeV it is 879.2 MBq/microAh. The radionuclidic impurity levels are discussed.

  3. Brookhaven leak reactor to close

    CERN Multimedia

    MacIlwain, C

    1999-01-01

    The DOE has announced that the High Flux Beam Reactor at Brookhaven is to close for good. Though the news was not unexpected researchers were angry the decision had been taken before the review to assess the impact of reopening the reactor had been concluded (1 page).

  4. Ecological Challenges for Closed Systems

    Science.gov (United States)

    Nelson, Mark; Dempster, William; Allen, John P.

    2012-07-01

    Closed ecological systems are desirable for a number of purposes. In space life support systems, material closure allows precious life-supporting resources to be kept inside and recycled. Closure in small biospheric systems facilitates detailed measurement of global ecological processes and biogeochemical cycles. Closed testbeds facilitate research topics which require isolation from the outside (e.g. genetically modified organisms; radioisotopes) so their ecological interactions and fluxes can be studied separate from interactions with the outside environment. But to achieve and maintain closure entails solving complex ecological challenges. These challenges include being able to handle faster cycling rates and accentuated daily and seasonal fluxes of critical life elements such as carbon dioxide, oxygen, water, macro- and mico-nutrients. The problems of achieving sustainability in closed systems for life support include how to handle atmospheric dynamics including trace gases, producing a complete human diet and recycling nutrients and maintaining soil fertility, the sustaining of healthy air and water and preventing the loss of crucial elements from active circulation. In biospheric facilities the challenge is also to produce analogues to natural biomes and ecosystems, studying processes of self-organization and adaptation in systems that allow specification or determination of state variables and cycles which may be followed through all interactions from atmosphere to soils. Other challenges include the dynamics and genetics of small populations, the psychological challenges for small isolated human groups and measures and options which may be necessary to ensure long-term operation of closed ecological systems.

  5. Works close to gate B

    CERN Multimedia

    GS Department

    2011-01-01

    In connection to the TRAM project, drainage works will be carried out close to gate B until the end of next week. In order to avoid access problems, if arriving by car, please use gates A and E. Department of General Infrastructure Services (GS) GS-SE Group

  6. Opening up closed policy communities.

    NARCIS (Netherlands)

    Termeer, C.J.A.M.; Werkman, R.A.

    2010-01-01

    Agricultural policy networks have served as classic cases of closed policy communities, facing pressure to open up. However attempts to involve new stakeholders slowly move forward. This paper addresses the question why it is so difficult to open up agricultural communities and what might help to

  7. Changing closed agricultural policy communities

    NARCIS (Netherlands)

    Termeer, C.J.A.M.; Werkman, R.A.

    2011-01-01

    Agricultural policy networks have served as classic examples of closed policy communities facing pressure to open up. However, attempts to change them are slowly moving forward. The dialogues on Common Agricultural Policy reforms in which the Dutch Ministry of Agriculture is engaged with a range of

  8. Police close unsolved 'climategate' investigation

    Science.gov (United States)

    Lavender, Gemma

    2012-09-01

    Police in Norfolk in the UK have closed an investigation into the hacking of e-mails at the University of East Anglia's Climate Research Unit (CRU) after admitting that they will not be able to find the hackers who broke into CRU computer servers.

  9. Determination of equilibrium fuel composition for fast reactor in closed fuel cycle

    Directory of Open Access Journals (Sweden)

    Ternovykha Mikhail

    2017-01-01

    Full Text Available Technique of evaluation of multiplying and reactivity characteristics of fast reactor operating in the mode of multiple refueling is presented. We describe the calculation model of the vertical section of the reactor. Calculation validations of the possibility of correct application of methods and models are given. Results on the isotopic composition, mass feed, and changes in the reactivity of the reactor in closed fuel cycle are obtained. Recommendations for choosing perspective fuel compositions for further research are proposed.

  10. Determination of equilibrium fuel composition for fast reactor in closed fuel cycle

    Science.gov (United States)

    Ternovykha, Mikhail; Tikhomirov, Georgy; Khomyakov, Yury; Suslov, Igor

    2017-09-01

    Technique of evaluation of multiplying and reactivity characteristics of fast reactor operating in the mode of multiple refueling is presented. We describe the calculation model of the vertical section of the reactor. Calculation validations of the possibility of correct application of methods and models are given. Results on the isotopic composition, mass feed, and changes in the reactivity of the reactor in closed fuel cycle are obtained. Recommendations for choosing perspective fuel compositions for further research are proposed.

  11. Second international conference on isotopes. Conference proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, C.J. [ed.

    1997-10-01

    The Second International Conference on Isotopes (2ICI) was hosted by the Australian Nuclear Association in Sydney, NSW, Australia. The Theme of the Second Conference: Isotopes for Industry, Health and a Better Environment recognizes that isotopes have been used in these fields successfully for many years and offer prospects for increasing use in the future. The worldwide interest in the use of research reactors and accelerators and in applications of stable and radioactive isotopes, isotopic techniques and radiation in industry, agriculture, medicine, environmental studies and research in general, was considered. Other radiation issues including radiation protection and safety were also addressed. International and national overviews and subject reviews invited from leading experts were included to introduce the program of technical sessions. The invited papers were supported by contributions accepted from participants for oral and poster presentation. A Technical Exhibition was held in association with the Conference. This volume contains the full text or extended abstracts of papers number 61- to number 114

  12. Selected Isotopes for Optimized Fuel Assembly Tags

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, David C.; Mitchell, Mark R.; Reid, Bruce D.; Gesh, Christopher J.; Hurley, David E.

    2008-10-01

    In support of our ongoing signatures project we present information on 3 isotopes selected for possible application in optimized tags that could be applied to fuel assemblies to provide an objective measure of burnup. 1. Important factors for an optimized tag are compatibility with the reactor environment (corrosion resistance), low radioactive activation, at least 2 stable isotopes, moderate neutron absorption cross-section, which gives significant changes in isotope ratios over typical fuel assembly irradiation levels, and ease of measurement in the SIMS machine 2. From the candidate isotopes presented in the 3rd FY 08 Quarterly Report, the most promising appear to be Titanium, Hafnium, and Platinum. The other candidate isotopes (Iron, Tungsten, exhibited inadequate corrosion resistance and/or had neutron capture cross-sections either too high or too low for the burnup range of interest.

  13. Oxygen isotope fractionation in stratospheric CO2

    Science.gov (United States)

    Thiemens, M. H.; Jackson, T.; Mauersberger, K.; Schueler, B.; Morton, J.

    1991-01-01

    A new cryogenic collection system has been flown on board a balloon gondola to obtain separate samples of ozone and carbon dioxide without entrapping major atmospheric gases. Precision laboratory isotopic analysis of CO2 samples collected between 26 and 35.5 km show a mass-independent enrichment in both O-17 and O-18 of about 11 per mil above tropospheric values. Ozone enrichment in its heavy isotopes was 9 to 16 percent in O3-50 and 8 to 11 percent in O3-49, respectively (Schueler et al., 1990). A mechanism to explain the isotope enrichment in CO2 has been recently proposed by Yung et al. (1991). The model is based on the isotope exchange between CO2 and O3 via O(1D), resulting in a transfer of the ozone isotope enrichment to carbon dioxide. Predicted enrichment and measured values agree well.

  14. Use of Multiple Isotopic Systems to Interpret Ecosystem Processes in Hawaii

    Science.gov (United States)

    Chadwick, O.; Derry, L.; Vitousek, P.

    2007-12-01

    The Hawaiian Islands are an excellent natural laboratory for studying the way in which ecosystems develop and function under varying climates. The mantle-derived basalt parent material provides a constant reaction matrix, the trade winds provide an asymmetric climate pattern that means that the same-age lava flows can be studied under different forcing factors, the relatively few plant species that made it to Hawaii provide a simplified biotic influence on substrate. In essence, we find that the geochemical evolution of basalt weathering provides shifting boundary conditions that constrain ecosystem potentialities, and allows us to apply a number of isotopic systems to enhance the specificity of our interpretation of ecosystem processes. We have applied the following isotopes to assist us in understanding the processes that impact ecosystems: O, C, Sr, Ca, N, Si and Be, and are presently exploring the use of S and Mg. We use these isotopic systems within a matrix of controls that allows us to focus on specific questions. The isotopic signatures from different isotopic systems can define climate- response patterns that are non-linear with each defining different threshold and plateau in rainfall space. Measurement of these isotopic systems allows us to evaluate multiple chemical behaviors at once and to evaluate expected responses to perturbations to any of these tracers in response to past or future changes in climate or other ecosystem drives such as land cover change. For instance, based on deep-soil samples, the plants that grew before humans reached Hawaii have C13 values that drop from -14 per mil to -26 per mil as rainfall increases from 200 mm to 3000 mm. Today the surface-soil values remain close to -14 per mil throughout the rainfall gradient due to the introduction of C4 grasses for pasture. Along the same rainfall gradient, Sr isotopes demonstrate that as C3 plants began to predominate there was a fundmental shift in nutrients supplied from rocks to

  15. Structures of the CAGE, Prism, and Book Hexamer Water Clusters from Multiple Isotopic Substitution

    Science.gov (United States)

    Lobsiger, Simon; Perez, Cristobal; Zaleski, Daniel P.; Seifert, Nathan; Pate, Brooks H.; Kisiel, Zbigniew; Temelso, Berhane; Shields, George C.

    2013-06-01

    The rotational spectra of the three lowest energy conformers of the water hexamer have recently been observed and assigned using chirped-pulse Fourier-transform microwave spectroscopy. In that study single ^{18}O isotopic substitution allowed determination of oxygen framework geometries for all three clusters. Further isotopic spectra have been recorded since then: of water samples with ^{18}O:^{16}O ratios of 3:1 and 1:3, and of weakly deuterated water. Each spectrum results from averaging of around 10M free-induction-decays and the achieved high S/N ratio allowed assignment for each cluster of isotopic species with practically all possible ^{16}O,^{18}O isotopic combinations, ranging from all ^{16}O to all ^{18}O species. In addition, all 12 single deuterium species of each conformer have been assigned. This unprecedented abundance of isotopic information, resulting in rotational constants for close to 228 different species, is combined in new determinations of the structures of these clusters, providing a deeper insight into the properties of the underlying hydrogen bonding. C. Perez, M. T. Muckle, D. P. Zaleski, N. A. Seifert, B. Temelso, G. C. Shields, Z. Kisiel, and B. H. Pate, Science {336}, 897 (2012).

  16. Sea ice control of water isotope transport to Antarctica and implications for ice core interpretation

    Science.gov (United States)

    Noone, David; Simmonds, Ian

    2004-04-01

    Sea ice in the Southern Ocean is important for Antarctic climate and hydrology. The dependence of water isotope abundance (δ18O and deuterium excess) on the winter sea ice state is examined with the isotopic version of the Melbourne University general circulation model. Reductions in the ice concentration provide warmer temperatures in winter and allow higher precipitation totals further south, while the reverse occurs with increased ice extent. The model shows clear demarcation between the changes in the isotopic conditions over the sea ice pack, where local changes in surface exchange dominate, and those of the continent interior, which depend on the long-ranged transport aloft. While less sensitive to the forcing, the interior response is influenced by changes in turbulent mixing over the ice pack and modification of the vertical transport associated with diabatic heating. The interior deuterium excess response is more strongly affected by sea ice as it captures changes in temperature over the ice rather than just the final vapor mass. Traditional reconstruction of temperature from a single isotopic nuclide would give erroneous interpretation of change in the global mean temperature unless the sea ice changes in parallel; instead, the spatial structure of the sea ice response gives some hope for extracting past sea ice conditions from multicore analysis. This study begins to explore the role of entropy production during transport such that the isotopic interpretation is more closely tied to the dynamics of the atmosphere than is expressed by idealized parcel analysis.

  17. Calculation of site-specific carbon-isotope fractionation in pedogenic oxide minerals

    Science.gov (United States)

    Rustad, James R.; Zarzycki, Piotr

    2008-01-01

    Ab initio molecular dynamics and quantum chemistry techniques are used to calculate the structure, vibrational frequencies, and carbon-isotope fractionation factors of the carbon dioxide component [CO2(m)] of soil (oxy)hydroxide minerals goethite, diaspore, and gibbsite. We have identified two possible pathways of incorporation of CO2(m) into (oxy)hydroxide crystal structures: one in which the C4+ substitutes for four H+ [CO2(m)A] and another in which C4+ substitutes for (Al3+,Fe3+) + H+ [CO2(m)B]. Calculations of isotope fractionation factors give large differences between the two structures, with the CO2(m)A being isotopically lighter than CO2(m)B by ≈10 per mil in the case of gibbsite and nearly 20 per mil in the case of goethite. The reduced partition function ratio of CO2(m)B structure in goethite differs from CO2(g) by 10 per mil higher, close to those measured for calcite and aragonite. The surprisingly large difference in the carbon-isotope fractionation factor between the CO2(m)A and CO2(m)B structures within a given mineral suggests that the isotopic signatures of soil (oxy)hydroxide could be heterogeneous. PMID:18641124

  18. Lead isotope variations across terrane boundaries of the Tien Shan and Chinese Altay

    Science.gov (United States)

    Chiaradia, Massimo; Konopelko, Dmitry; Seltmann, Reimar; Cliff, Robert A.

    2006-08-01

    The Altaid orogen was formed by aggregation of Paleozoic subduction-accretion complexes and Precambrian basement blocks between the Late Proterozoic and the Early Mesozoic. Because the Altaids are the site of abundant granitic plutonism and host some of the largest gold deposits in the world, understanding their formation has important implications on the comprehension of Phanerozoic crustal growth and metallogeny. In this study, we present the first extensive lead isotope data on magmatic and metasedimentary rocks as well as ore deposits of the southern part of the Altaids, including the Tien Shan (Tianshan) and southern Altay (Altai) orogenic belts. Our results show that each terrane investigated within the Tien Shan and southern Altay is characterized by a distinct Pb isotope signature and that there is a SW-NE Pb isotope gradient suggesting a progressive transition from a continental crust environment in the West (the Kyzylkum and Kokshaal segments of the Southern Tien Shan) to an almost 100% juvenile (MORB-type mantle-derived) crust environment in the East (Altay). The Pb isotope signatures of the studied ore deposits follow closely those of magmatic and metasedimentary rocks of the host terranes, thus supporting the validity of lead isotopes to discriminate terranes. Whereas this apparently suggests that no unique reservoir has been responsible for the huge gold concentration in this region, masking of a preferential Pb-poor Au-bearing reservoir by mixing with Pb-rich crustal reservoirs during the mineralizing events cannot be excluded.

  19. Fractionation of sulfur and hydrogen isotopes in Desulfovibrio vulgaris with perturbed DsrC expression.

    Science.gov (United States)

    Leavitt, William D; Venceslau, Sofia S; Pereira, Inês A C; Johnston, David T; Bradley, Alexander S

    2016-10-01

    Dissimilatory sulfate reduction is the central microbial metabolism in global sulfur cycling. Understanding the importance of sulfate reduction to Earth's biogeochemical S cycle requires aggregating single-cell processes with geochemical signals. For sulfate reduction, these signals include the ratio of stable sulfur isotopes preserved in minerals, as well as the hydrogen isotope ratios and structures of microbial membrane lipids preserved in organic matter. In this study, we cultivated the model sulfate reducer, Desulfovibrio vulgaris DSM 644T, to investigate how these parameters were perturbed by changes in expression of the protein DsrC. DsrC is critical to the final metabolic step in sulfate reduction to sulfide. S and H isotopic fractionation imposed by the wild type was compared to three mutants. Discrimination against 34S in sulfate, as calculated from the residual reactant, did not discernibly differ among all strains. However, a closed-system sulfur isotope distillation model, based on accumulated sulfide, produced inconsistent results in one mutant strain IPFG09. Lipids produced by IPFG09 were also slightly enriched in 2H. These results suggest that DsrC alone does not have a major impact on sulfate-S, though may influence sulfide-S and lipid-H isotopic compositions. While intriguing, a mechanistic explanation requires further study under continuous culture conditions. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Manus Water Isotope Investigation Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Jessica L [University of Illinois, Urbana-Champaign; Cobb, Kim M [Georgia Institute of Technology; Noone, David [University of Colorado, Boulder

    2016-03-01

    The objective of this field campaign was to investigate climatic controls on the stable isotopic composition of water vapor, precipitation, and seawater in the western tropical Pacific. Simultaneous measurements of the stable isotopic composition of vapor and precipitation from April 28 to May 8, 2013, at the Manus Tropical Western Pacific Atmospheric Radiation Measurement site, provided several key insights into the nature of the climate signal archived in precipitation and vapor isotope ratios. We observed a large shift from lower to higher isotopic values in vapor and precipitation because of the passage of a mesoscale convective system west of the site and a transition from a regional stormy period into a more quiescent period. During the quiescent period, the stable isotopic composition of vapor and precipitation indicated the predominance of oceanic evaporation in determining the isotopic composition of boundary-layer vapor and local precipitation. There was not a consistent relationship between intra-event precipitation amount at the site and the stable isotopic composition of precipitation, thus challenging simplified assumptions about the isotopic “amount effect” in the tropics on the time scale of individual storms. However, some storms did show an amount effect, and deuterium excess values in precipitation had a significant relationship with several meteorological variables, including precipitation, temperature, relative humidity, and cloud base height across all measured storms. The direction of these relationships points to condensation controls on precipitation deuterium excess values on intra-event time scales. The relationship between simultaneous measurements of vapor and precipitation isotope ratios during precipitation events indicates the ratio of precipitation-to-vapor isotope ratios can diagnose precipitation originating from a vapor source unique from boundary-layer vapor and rain re-evaporation.