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Sample records for au melange co2-ch4

  1. Modified ZIF-8 mixed matrix membrane for CO2/CH4 separation

    Science.gov (United States)

    Nordin, Nik Abdul Hadi Md; Ismail, Ahmad Fauzi; Misdan, Nurasyikin; Nazri, Noor Aina Mohd

    2017-10-01

    Tunability of metal-organic frameworks (MOFs) properties enables them to be tailored for specific applications. In this study, zeolitic imidazole framework 8 (ZIF-8), sub-class of MOF, underwent pre-synthesis and post-synthesis modifications. The pre-synthesis modification using GO (ZIF-8/GO) shows slight decrease in textural properties, while the post-synthesis modification using amine solution (ZIF-8/NH2) resulted in superior BET surface area and pore volume. Mixed matrix membranes (MMMs) derived from polysulfone (PSf) and the modified ZIF-8s were then prepared via dry/wet phase inversion. The polymer chain flexibility of the resulted MMMs shows rigidification, where ZIF-8/NH2 as filler resulting higher rigidification compared to ZIF-8/GO. The MMMs were further subjected to pure CO2 and CH4 gas permeation experiments. The PSf/ZIF-8/NH2 shows superior CO2/CH4 selectivity (88% increased) while sacrificing CO2 permeance due to combination of severe polymer chain rigidification and the presence of CO2-philic group, amine. Whereas, the PSf/ZIF-8/GO possess 64% increase in CO2 permeance without notable changes in CO2/CH4 selectivity.

  2. Airborne measurements of CO2, CH4 and HCN in boreal biomass burning plumes

    Science.gov (United States)

    O'Shea, Sebastian J.; Bauguitte, Stephane; Muller, Jennifer B. A.; Le Breton, Michael; Archibald, Alex; Gallagher, Martin W.; Allen, Grant; Percival, Carl J.

    2013-04-01

    Biomass burning plays an important role in the budgets of a variety of atmospheric trace gases and particles. For example, fires in boreal Russia have been linked with large growths in the global concentrations of trace gases such as CO2, CH4 and CO (Langenfelds et al., 2002; Simpson et al., 2006). High resolution airborne measurements of CO2, CH4 and HCN were made over Eastern Canada onboard the UK Atmospheric Research Aircraft FAAM BAe-146 from 12 July to 4 August 2011. These observations were made as part of the BORTAS project (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites). Flights were aimed at transecting and sampling the outflow from the commonly occurring North American boreal forest fires during the summer months and to investigate and identify the chemical composition and evolution of these plumes. CO2 and CH4 dry air mole fractions were determined using an adapted system based on a Fast Greenhouse Gas Analyser (FGGA, Model RMT-200) from Los Gatos Research Inc, which uses the cavity enhanced absorption spectroscopy technique. In-flight calibrations revealed a mean accuracy of 0.57 ppmv and 2.31 ppbv for 1 Hz observations of CO2 and CH4, respectively, during the BORTAS project. During these flights a number of fresh and photochemically-aged plumes were identified using simultaneous HCN measurements. HCN is a distinctive and useful marker for forest fire emissions and it was detected using chemical ionisation mass spectrometry (CIMS). In the freshest plumes, strong relationships were found between CH4, CO2 and other tracers for biomass burning. From this we were able to estimate that 8.5 ± 0.9 g of CH4 and 1512 ± 185 g of CO2 were released into the atmosphere per kg of dry matter burnt. These emission factors are in good agreement with estimates from previous studies and can be used to calculate budgets for the region. However for aged plumes the correlations between CH4 and other

  3. Role of cation in target adsorption of carbon dioxide from CO2-CH4 mixture by low silica X zeolites

    Science.gov (United States)

    Hasegawa, Keiichi; Matsumoto, Akihiko

    2017-07-01

    The adsorption features of CO2 from a model biogas CO2-CH4 mixture (CO2/CH4 = 2/3 v/v) on low-silica X zeolites (LSX) with different cations Li+, Na+ and Ca2+ (Li-, Na- and Ca-LSX) were characterized by adsorption microcalorimetry and vacuum pressure swing adsorption (VPSA) technique to reveal the effect of cation species on CO2 adsorption. The order of the differential heat of adsorption (Qdif) of CO2 on LSX zeolites was Li-LSX > Na-LSX > Ca-LSX, indicating the strongest interaction of Li-LSX due to the smallest ionic radius of Li+. In-situ FT-IR spectrum of Ca-LSX outgassed at 623 K and Qdif of ammonia (NH3) suggest that cation sites of Ca-LSX are Ca(OH)+ and acidic silanol (Si-OH) rather than bare Ca2+. Since the ionic radius of Ca(OH)+ is the largest among the cations and the H+ site doesn't form electrostatic field, Qdif of Ca-LSX was the lowest. The VPSA experiment showed that the breakthrough time of CO2 was the longest and the adsorption amount was the highest for Na-LSX among the LSX samples. These evidences indicate Na-LSX is the most preferable adsorbent zeolite in the CO2 separation from the CO2-CH4 mixture.

  4. Competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons: effects of edge-functionalization.

    Science.gov (United States)

    Lu, Xiaoqing; Jin, Dongliang; Wei, Shuxian; Zhang, Mingmin; Zhu, Qing; Shi, Xiaofan; Deng, Zhigang; Guo, Wenyue; Shen, Wenzhong

    2015-01-21

    The effect of edge-functionalization on the competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons (NPCs) has been investigated for the first time by combining density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation. Our results show that edge-functionalization has a more positive effect on the single-component adsorption of CO2 than CH4, therefore significantly enhancing the selectivity of CO2 over CH4, in the order of NH2-NPC > COOH-NPC > OH-NPC > H-NPC > NPC at low pressure. The enhanced adsorption originates essentially from the effects of (1) the conducive environment with a large pore size and an effective accessible surface area, (2) the high electronegativity/electropositivity, (3) the strong adsorption energy, and (4) the large electrostatic contribution, due to the inductive effect/direct interaction of the embedded edge-functionalized groups. The larger difference from these effects results in the higher competitive adsorption advantage of CO2 in the binary CO2-CH4 mixture. Temperature has a negative effect on the gas adsorption, but no obvious influence on the electrostatic contribution on selectivity. With the increase of pressure, the selectivity of CO2 over CH4 first decreases sharply and subsequently flattens out to a constant value. This work highlights the potential of edge-functionalized NPCs in competitive adsorption, capture, and separation for the binary CO2-CH4 mixture, and provides an effective and superior alternative strategy in the design and screening of adsorbent materials for carbon capture and storage.

  5. Hydrogenation of organic matter as a terminal electron sink sustains high CO 2 :CH 4 production ratios during anaerobic decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Rachel M.; Tfaily, Malak M.; Rich, Virginia I.; Keller, Jason K.; Bridgham, Scott D.; Zalman, Cassandra Medvedeff; Meredith, Laura; Hanson, Paul J.; Hines, Mark; Pfeifer-Meister, Laurel; Saleska, Scott R.; Crill, Patrick; Cooper, William T.; Chanton, Jeff P.; Kostka, Joel E.

    2017-10-01

    Once inorganic electron acceptors are depleted, organic matter in anoxic environments decomposes by hydrolysis, fermentation, and methanogenesis, requiring syntrophic interactions between microorganisms to achieve energetic favorability. In this classic anaerobic food chain, methanogenesis represents the terminal electron accepting (TEA) process, ultimately producing equimolar CO2 and CH4 for each molecule of organic matter degraded. However, CO2:CH4 production in Sphagnum-derived, mineral-poor, cellulosic peat often substantially exceeds this 1:1 ratio, even in the absence of measureable inorganic TEAs. Since the oxidation state of C in both cellulose-derived organic matter and acetate is 0, and CO2 has an oxidation state of +4, if CH4 (oxidation state -4) is not produced in equal ratio, then some other compound(s) must balance CO2 production by receiving 4 electrons. Here we present evidence for ubiquitous hydrogenation of diverse unsaturated compounds that appear to serve as organic TEAs in peat, thereby providing the necessary electron balance to sustain CO2:CH4 >1. While organic electron acceptors have previously been proposed to drive microbial respiration of organic matter through the reversible reduction of quinone moieties, the hydrogenation mechanism that we propose, by contrast, reduces C-C double bonds in organic matter thereby serving as 1) a terminal electron sink, 2) a mechanism for degrading complex unsaturated organic molecules, 3) a potential mechanism to regenerate electron-accepting quinones, and, in some cases, 4) a means to alleviate the toxicity of unsaturated aromatic acids. This mechanism for CO2 generation without concomitant CH4 production has the potential to regulate the global warming potential of peatlands by elevating CO2:CH4 production ratios.

  6. Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system

    Science.gov (United States)

    Qin, J.; Rosenbauer, R.J.; Duan, Zhenhao

    2008-01-01

    Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

  7. Modeling permeation of CO2/CH4, N2/CH4, and CO2/air mixtures across a DD3R zeolite membrane

    NARCIS (Netherlands)

    van den Bergh, J.; Mittelmeijer-Hazeleger, M.; Kapteijn, F.

    2010-01-01

    Single component (CO2, CH4, and N2) and equimolar binary mixture (CO2/CH4, N2/CH4, and CO2/Air) permeation data across a disk-shaped all-silica DDR zeolite membrane have been the subject of a thorough modeling study over a challenging broad temperature (220−373 K) and feed pressure (101−1500 kPa)

  8. Plasticization-resistant hollow fiber membranes for CO2/CH4 separation based on a thermally crosslinkable polyimide

    KAUST Repository

    Chen, Chien-Chiang

    2011-10-01

    Decarboxylation-induced thermal crosslinking has been demonstrated to be effective for stabilizing membranes against plasticization in dense films. This study extends this promising crosslinking approach from dense films to industrially relevant asymmetric hollow fiber membranes. Crosslinkable asymmetric hollow fiber membranes were spun from a carboxylic acid containing polyimide, 6FDA-DAM:DABA. Dope and spinning conditions were optimized to obtain fibers with a defect-free selective skin layer. It is found that slightly defective fibers suffered severe selectivity loss after thermal crosslinking, suggesting that defect-free property is essential to the performance of the resulting crosslinked hollow fiber membranes. The crosslinked fibers were tested for CO 2/CH 4 separation. The excellent plasticization resistance under high pressure feeds (with highest CO 2 partial pressure of 400psia) suggests that these robust membranes are promising for aggressive natural gas purification. © 2011 Elsevier B.V.

  9. Development and characterization of polyethersulfone/TiO2 mixed matrix membranes for CO2/CH4 separation

    Science.gov (United States)

    Galaleldin, S.; Mannan, H. A.; Mukhtar, H.

    2017-12-01

    In this study, mixed matrix membranes comprised of polyethersulfone as the bulk polymer phase and titanium dioxide (TiO2) nanoparticles as the inorganic discontinuous phase were prepared for CO2/CH4 separation. Membranes were synthesized at filler loading of 0, 5, 10 and 15 wt % via dry phase inversion method. Morphology, chemical bonding and thermal characteristics of membranes were scrutinized utilizing different techniques, namely: Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform InfraRed (FTIR) spectra and Thermogravimetric analysis (TGA) respectively. Membranes gas separation performance was evaluated for CO2 and CH4 gases at 4 bar feed pressure. The highest separation performance was achieved by mixed matrix membrane (MMM) at 5 % loading of TiO2.

  10. Estimating Landfill Methane Oxidation Using the Information of CO2/CH4 Fluxes Measured By the Eddy Covariance Method

    Science.gov (United States)

    Xu, L.; McDermitt, D. K.; Li, J.; Green, R. B.

    2016-12-01

    Methane plays a critical role in the radiation balance and chemistry of the atmosphere. Globally, landfill methane emission contributes about 10-19% of the anthropogenic methane burden into the atmosphere. In the United States, 18% of annual anthropogenic methane emissions come from landfills, which represent the third largest source of anthropogenic methane emissions, behind enteric fermentation and natural gas and oil production. One uncertainty in estimating landfill methane emissions is the fraction of methane oxidized when methane produced under anaerobic conditions passes through the cover soil. We developed a simple stoichiometric model to estimate the landfill methane oxidation fraction when the anaerobic CO2/CH4 production ratio is known. The model predicts a linear relationship between CO2 emission rates and CH4 emission rates, where the slope depends on anaerobic CO2/CH4 production ratio and the fraction of methane oxidized, and the intercept depends on non-methane-dependent oxidation processes. The model was tested with eddy covariance CO2 and CH4 emission rates at Bluff Road Landfill in Lincoln Nebraska. It predicted zero oxidation rate in the northern portion of this landfill where a membrane and vents were present. The zero oxidation rate was expected because there would be little opportunity for methane to encounter oxidizing conditions before leaving the vents. We also applied the model at the Turkey Run Landfill in Georgia to estimate the CH4 oxidation rate over a one year period. In contrast to Bluff Road Landfill, the Turkey Run Landfill did not have a membrane or vents. Instead, methane produced in the landfill had to diffuse through a 0.5 m soil cap before release to the atmosphere. We observed evidence for methane oxidation ranging from about 18% to above 60% depending upon the age of deposited waste material. The model will be briefly described, and results from the two contrasting landfills will be discussed in this presentation.

  11. CO2, CH4 and N2O fluxes from soil of a burned grassland in Central Africa

    Directory of Open Access Journals (Sweden)

    R. Valentini

    2010-11-01

    Full Text Available The impact of fire on soil fluxes of CO2, CH4 and N2O was investigated in a tropical grassland in Congo Brazzaville during two field campaigns in 2007–2008. The first campaign was conducted in the middle of the dry season and the second at the end of the growing season, respectively one and eight months after burning. Gas fluxes and several soil parameters were measured in each campaign from burned plots and from a close-by control area preserved from fire. Rain events were simulated at each campaign to evaluate the magnitude and duration of the generated gas flux pulses. In laboratory experiments, soil samples from field plots were analysed for microbial biomass, net N mineralization, net nitrification, N2O, NO and CO2 emissions under different water and temperature soil regimes. One month after burning, field CO2 emissions were significantly lower in burned plots than in the control plots, the average daily CH4 flux shifted from net emission in the unburned area to net consumption in burned plots, no significant effect of fire was observed on soil N2O fluxes. Eight months after burning, the average daily fluxes of CO2, CH4 and N2O measured in control and burned plots were not significantly different. In laboratory, N2O fluxes from soil of burned plots were significantly higher than fluxes from soil of unburned plots only above 70% of maximum soil water holding capacity; this was never attained in the field even after rain simulation. Higher NO emissions were measured in the lab in soil from burned plots at both 10% and 50% of maximum soil water holding capacity. Increasing the incubation temperature from 25 °C to 37 °C negatively affected microbial growth, mineralization and nitrification activities but enhanced N2O and CO2 production. Results indicate that fire did not increase post-burning soil GHG emissions in this tropical grasslands characterized by acidic, well drained and nutrient-poor soil.

  12. Fabrication of 6FDA-durene membrane incorporated with zeolite T and aminosilane grafted zeolite T for CO2/CH4 separation

    Science.gov (United States)

    Jusoh, Norwahyu; Fong Yeong, Yin; Keong Lau, Kok; Shariff, Azmi Mohd

    2017-08-01

    In the present work, zeolite T and aminosilane grafted zeolite T are embedded into 6FDA-durene polyimide phase for the fabrication of mixed matrix membranes (MMMs). FESEM images demonstrated that the improvement of interfacial adhesion between zeolite and polymer phases in MMM loaded with aminosilane grafted zeolite T was not significant as compared to zeolite T/6FDA-durene MMM. From the gas permeation test, CO2/CH4 selectivity up to 26.4 was achieved using MMM containing aminosilane grafted zeolite T, while MMM loaded with ungrafted zeolite T showed CO2/CH4 selectivity of 19.1. In addition, MMM incorporated with aminosilane grafted zeolite T particles successfully lies on Robeson upper bound 2008, which makes it an attractive candidate for CO2/CH4 separation.

  13. Transport Mechanisms for CO2-CH4 Exchange and Safe CO2 Storage in Hydrate-Bearing Sandstone

    Directory of Open Access Journals (Sweden)

    Knut Arne Birkedal

    2015-05-01

    Full Text Available CO2 injection in hydrate-bearing sediments induces methane (CH4 production while benefitting from CO2 storage, as demonstrated in both core and field scale studies. CH4 hydrates have been formed repeatedly in partially water saturated Bentheim sandstones. Magnetic Resonance Imaging (MRI and CH4 consumption from pump logs have been used to verify final CH4 hydrate saturation. Gas Chromatography (GC in combination with a Mass Flow Meter was used to quantify CH4 recovery during CO2 injection. The overall aim has been to study the impact of CO2 in fractured and non-fractured samples to determine the performance of CO2-induced CH4 hydrate production. Previous efforts focused on diffusion-driven exchange from a fracture volume. This approach was limited by gas dilution, where free and produced CH4 reduced the CO2 concentration and subsequent driving force for both diffusion and exchange. This limitation was targeted by performing experiments where CO2 was injected continuously into the spacer volume to maintain a high driving force. To evaluate the effect of diffusion length multi-fractured core samples were used, which demonstrated that length was not the dominating effect on core scale. An additional set of experiments is presented on non-fractured samples, where diffusion-limited transportation was assisted by continuous CO2 injection and CH4 displacement. Loss of permeability was addressed through binary gas (N2/CO2 injection, which regained injectivity and sustained CO2-CH4 exchange.

  14. Adsorptive behavior of CO2, CH4 and their mixtures in carbon nanospace: a molecular simulation study.

    Science.gov (United States)

    Palmer, Jeremy C; Moore, Joshua D; Roussel, Thomas J; Brennan, John K; Gubbins, Keith E

    2011-03-07

    Using molecular simulation, four types of nanoporous carbons are examined as adsorbents for the separation of CO(2)/CH(4) mixtures at ambient temperature and pressures up to 10 MPa. First, the adsorption selectivity of CO(2) is investigated in carbon slit pores and single-walled carbon nanotube bundles in order to find the optimal pore dimensions for CO(2) separation. Then, the adsorptive properties of the optimized slit pore and nanotube bundle are compared with two realistic nanoporous carbon models: a carbon replica of zeolite Y and an amorphous carbon. For the four carbon models, adsorption isotherms and isosteric heats of adsorption are presented for both pure components and mixtures. Special attention is given to the calculation of excess isotherms and isosteric heats, which are necessary to assess the performance of model nanoporous materials in the context of experimental measurements. From these results, we discuss the impact that variables such as pore size, pore morphology, pressure and mixture composition have on the performance of nanoporous carbons for CO(2) separation.

  15. Investigating cluster formation in adsorption of CO2, CH4, and Ar in zeolites and metal organic frameworks at subcritical temperatures

    NARCIS (Netherlands)

    Krishna, R.; van Baten, J.M.

    2010-01-01

    The critical temperatures, T-c, of CO2, CH4, and Ar are 304 K, 191 K, and 151 K, respectively. This paper highlights some unusual characteristics of adsorption and diffusion of these molecules in microporous structures such as zeolites and metal organic frameworks at temperatures T < T-c. Published

  16. A single gas chromatograph for accurate atmospheric mixing ratio measurements of CO2, CH4, N2O, SF6 and CO

    NARCIS (Netherlands)

    van der Laan, S.; Neubert, R. E. M.; Meijer, H. A. J.; Simpson, W.R.

    2009-01-01

    We present an adapted gas chromatograph capable of measuring simultaneously and semi-continuously the atmospheric mixing ratios of the greenhouse gases CO2, CH4, N2O and SF6 and the trace gas CO with high precision and long-term stability. The novelty of our design is that all species are measured

  17. Pure- and mixed-gas CO2/CH4 separation properties of PIM-1 and an amidoxime-functionalized PIM-1

    KAUST Repository

    Swaidan, Raja

    2014-05-01

    The prototypical solution-processable polymer of intrinsic microporosity, PIM-1, and derivatives thereof offer combinations of permeability and selectivity that make them potential candidate materials for membrane-based gas separations. Paramount to the design and evaluation of PIMs for economical natural gas sweetening is a high and stable CO2/CH4 selectivity under realistic, mixed-gas conditions. Here, amidoxime-functionalized PIM-1 (AO-PIM-1) was prepared and examined for fundamental structure/property relationships. Qualitative NLDFT pore-size distribution analyses of physisorption isotherms (N2 at -196 oC; CO2 at 0 oC) reveal a tightened microstructure indicating size-sieving ultra-microporosity (<7Å). AO-PIM-1 demonstrated a three-fold increase in αD(CO2/CH4) over PIM-1, surpassing the 2008 upper bound with P(CO2)=1153Barrer and ideal α(CO2/CH4)=34. Under a 50:50 CO2:CH4 mixed-gas feed, AO-PIM-1 showed less selectivity loss than PIM-1, maintaining a mixed-gas α(CO2/CH4) ~21 across a 20bar pressure range. Conversely, PIM-1 endured up to 60% increases in mixed-gas CH4 permeability over pure-gas values concurrent with a selectivity of only ~8 at 20bar. A pervasive intermolecular hydrogen bonding network in AO-PIM-1 predominantly yields a rigidified microstructure that mitigates CO2-induced matrix dilations, reducing detrimental mixed-gas CH4 copermeation. © 2014 Elsevier B.V.

  18. Pure- and Mixed-Gas Permeation Properties of Highly Selective and Plasticization Resistant Hydroxyl-Diamine-Based 6FDA Polyimides for CO2/CH4 Separation

    KAUST Repository

    Alaslai, Nasser Y.

    2016-01-05

    The effect of hydroxyl functionalization on the m-phenylene diamine moiety of 6FDA dianhydride-based polyimides was investigated for gas separation applications. Pure-gas permeability coefficients of He, H2, N2, O2, CH4, and CO2 were measured at 35 °C and 2 atm. The introduction of hydroxyl groups in the diamine moiety of 6FDA-diaminophenol (DAP) and 6FDA-diamino resorcinol (DAR) polyimides tightened the overall polymer structure due to increased charge transfer complex formation compared to unfunctionalized 6FDA-m-phenylene diamine (mPDA). The BET surface areas based on nitrogen adsorption of 6FDA-DAP (54 m2g−1) and of 6FDA-DAR (45 m2g−1) were ~18% and 32% lower than that of 6FDA-mPDA (66 m2g−1). 6FDA-mPDA had a pure-gas CO2 permeability of 14 Barrer and CO2/CH4 selectivity of 70. The hydroxyl-functionalized polyimides 6FDA-DAP and 6FDA-DAR exhibited very high pure-gas CO2/CH4 selectivities of 92 and 94 with moderate CO2 permeability of 11 and 8 Barrer, respectively. It was demonstrated that hydroxyl-containing polyimide membranes maintained very high CO2/CH4 selectivity (~ 75 at CO2 partial pressure of 10 atm) due to CO2 plasticization resistance when tested under high-pressure mixed-gas conditions. Functionalization with hydroxyl groups may thus be a promising strategy towards attaining highly selective polyimides for economical membrane-based natural gas sweetening.

  19. Role of intrachain rigidity in the plasticization of intrinsically microporous triptycene-based polyimide membranes in mixed-Gas CO2/CH4 separations

    KAUST Repository

    Swaidan, Raja

    2014-11-11

    Based on high-pressure pure- and mixed-gas (50:50) CO2/CH4 separation properties of two intrinsically microporous triptycene-based polyimides (TPDA-TMPD and TPDA-6FpDA), the intrachain rigidity central to "conventional PIM" design principles is not a singular solution to intrinsic plasticization resistance. Despite the significant intrachain rigidity in TPDA-TMPD, a 300% increase in PMIX(CH4), 50% decrease in α(CO2/CH4) from 24 to 12, and continuous increase in PMIX(CO2) occurred from 4 to 30 bar. On the other hand, the more flexible and densely packed TPDA-6FpDA exhibited a slight upturn in PMIX(CO2) at 20 bar similar to a dense cellulose acetate (CA) film, also reported here, despite a 4-fold higher CO2 sorption capacity. Microstructural investigations suggest that the interconnected O2- and H2-sieving ultramicroporosity of TPDA-TMPD is more sensitive to slight CO2-induced dilations and is the physical basis for a more extensive and accelerated plasticization. Interchain rigidity, potentially by interchain interactions, is emphasized and may be facilitated by intrachain mobility.

  20. Adsorption kinetics of CO2, CH4, and their equimolar mixture on coal from the Black Warrior Basin, West-Central Alabama

    Science.gov (United States)

    Gruszkiewicz, M.S.; Naney, M.T.; Blencoe, J.G.; Cole, D.R.; Pashin, J.C.; Carroll, R.E.

    2009-01-01

    Laboratory experiments were conducted to investigate the adsorption kinetic behavior of pure and mixed gases (CO2, CH4, approximately equimolar CO2 + CH4 mixtures, and He) on a coal sample obtained from the Black Warrior Basin at the Littleton Mine (Twin Pine Coal Company), Jefferson County, west-central Alabama. The sample was from the Mary Lee coal zone of the Pottsville Formation (Lower Pennsylvanian). Experiments with three size fractions (45-150????m, 1-2??mm, and 5-10??mm) of crushed coal were performed at 40????C and 35????C over a pressure range of 1.4-6.9??MPa to simulate coalbed methane reservoir conditions in the Black Warrior Basin and provide data relevant for enhanced coalbed methane recovery operations. The following key observations were made: (1) CO2 adsorption on both dry and water-saturated coal is much more rapid than CH4 adsorption; (2) water saturation decreases the rates of CO2 and CH4 adsorption on coal surfaces, but it appears to have minimal effects on the final magnitude of CO2 or CH4 adsorption if the coal is not previously exposed to CO2; (3) retention of adsorbed CO2 on coal surfaces is significant even with extreme pressure cycling; and (4) adsorption is significantly faster for the 45-150????m size fraction compared to the two coarser fractions. ?? 2008 Elsevier B.V.

  1. Molecular simulation of CO2/CH4 adsorption in brown coal: Effect of oxygen-, nitrogen-, and sulfur-containing functional groups

    Science.gov (United States)

    Dang, Yong; Zhao, Lianming; Lu, Xiaoqing; Xu, Jing; Sang, Pengpeng; Guo, Sheng; Zhu, Houyu; Guo, Wenyue

    2017-11-01

    The CO2/CH4 adsorption behaviors in brown coal at the temperatures of 298, 313, and 373 K and in the pressure range of 0.005-10 MPa were investigated by molecular dynamics (MD), density functional theory (DFT), and grand canonical Monte Carlo (GCMC) simulations. The absolute adsorption isotherms of single-component CH4 and CO2 exhibit type-I Langmuir adsorption behavior showing a negative influence of temperature. For the binary CO2/CH4 mixture, brown coal shows super high selectivity of CO2 over CH4 at pressures below 0.2 MPa, which then decreases quickly and finally tends to be constant when the pressure increases. The high competitive adsorption of CO2 originates from the effects of (i) the large electrostatic contributions, (ii) the conducive micropore environment with pore sizes below 0.56 nm, and (iii) the stronger adsorption of CO2 with respect to CH4. These effects are strengthened by the high-density oxygen-containing, pyridine, and thiophene functional groups contained in brown coal, which provide abundant and strong adsorption sites for CO2, but show weaker affinity to CH4. Furthermore, the influence of various nitrogen- and sulfur-containing functional groups on the CO2 adsorption capacity was also investigated. The results indicate that the basicity of the oxygen- and nitrogen-containing groups has a large influence on the CO2 adsorption, while for the sulfur functional groups the determining factor is the polarity.

  2. Tower measurement network of in-situ CO2, CH4, and CO in support of the Indianapolis FLUX (INFLUX Experiment

    Directory of Open Access Journals (Sweden)

    Scott J. Richardson

    2017-10-01

    Full Text Available A twelve-station tower-based observation network measuring CO2, CH4, and CO was deployed in and around the Indianapolis, IN metropolitan area as part of the Indianapolis Flux Experiment (INFLUX. Measurements began in 2010 and the full network was deployed by 2013. Observations were made at heights ranging from 39 to 136 m above ground level using existing communication towers. Several towers in the network had multiple measurement levels. Cavity ring-down spectrometers (CRDS were used at all twelve sites and at least one calibrated reference tank was sampled daily at each site. Real time data communications were performed via cellular modems and data were transmitted daily for processing and quality assurance checks. Data quality control procedures were utilized to ensure compatibility within the INFLUX tower network and with global standards. For example, field target/calibration tanks were used to detect long-term instrument drift and instrument failure. Network-wide round robin tests were performed every 1–2 years to detect possible target tank drift and ensure network-wide comparability between measurements. NOAA flask packages were deployed at six of the INFLUX towers to provide a flask to in-situ direct comparison of the atmospheric samples. Results from these activities demonstrate that the compatibility of the CO2, CH4, and CO INFLUX in-situ tower-based measurements are less than or equal to 0.18 ppm CO2, 1.0 ppb for CH4, and 6 ppb for CO.

  3. Diurnal variation of CO2, CH4, and N2O emission fluxes continuously monitored in-situ in three environmental habitats in a subtropical estuarine wetland.

    Science.gov (United States)

    Yang, Wen-Bin; Yuan, Chung-Shin; Tong, Chuan; Yang, Pin; Yang, Lei; Huang, Bang-Qin

    2017-06-15

    Wetlands play a crucial role in modulating atmospheric concentrations of greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The key factors controlling GHG emission from subtropical estuarine wetlands were investigated in this study, which continuously monitored the uptake/emission of GHGs (CO2, CH4, and N2O) by/from a subtropical estuarine wetland located in the Minjiang estuary in the coastal region of southeastern China. A self-designed floating chamber was used to collect air samples on-site at three environmental habitats (Phragmites australis marsh, mudflats, and river water). The CO2, CH4, and N2O concentrations were then measured using an automated nondispersive infrared analyzer. The magnitudes of the CO2 and N2O emission fluxes at the three habitats were ordered as river water>P. australis>mudflats. P. australis emitted GHGs through photosynthesis and respiration processes. Emissions of CH4 from P. australis and the mudflats were revealed to be slightly higher than those from the river water. The total GHG emission fluxes at the three environmental habitats were quite similar (4.68-4.78gm-2h-1). However, when the total carbon dioxide equivalent fluxes (CO2-e) were considered, the river water was discovered to emit the most CO2-e compared with P. australis and the mudflats. Based on its potential to increase global warming, N2O was the main contributor to the total GHG emission, with that emitted from the river water being the most considerable. Tidal water carried onto the marsh had its own GHG content and thus has acted as a source or sink of GHGs. However, water quality had a large effect on GHG emissions from the river water whereas the tidal water height did not. Both high salinity and large amounts of sulfates in the wetlands explicitly inhibited the activity of CH4-producing bacteria, particularly at nighttime. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Absolute accuracy and sensitivity analysis of OP-FTIR retrievals of CO2, CH4 and CO over concentrations representative of "clean air" and "polluted plumes"

    Directory of Open Access Journals (Sweden)

    D. W. T. Griffith

    2011-01-01

    Full Text Available When compared to established point-sampling methods, Open-Path Fourier Transform Infrared (OP-FTIR spectroscopy can provide path-integrated concentrations of multiple gases simultaneously, in situ and near-continuously. The trace gas pathlength amounts can be retrieved from the measured IR spectra using a forward model coupled to a non-linear least squares fitting procedure, without requiring "background" spectral measurements unaffected by the gases of interest. However, few studies have investigated the accuracy of such retrievals for CO2, CH4 and CO, particularly across broad concentration ranges covering those characteristic of ambient to highly polluted air (e.g. from biomass burning or industrial plumes. Here we perform such an assessment using data collected by a field-portable FTIR spectrometer. The FTIR was positioned to view a fixed IR source placed at the other end of an IR-transparent cell filled with the gases of interest, whose target concentrations were varied by more than two orders of magnitude. Retrievals made using the model are complicated by absorption line pressure broadening, the effects of temperature on absorption band shape, and by convolution of the gas absorption lines and the instrument line shape (ILS. Despite this, with careful model parameterisation (i.e. the optimum wavenumber range, ILS, and assumed gas temperature and pressure for the retrieval, concentrations for all target gases were able to be retrieved to within 5%. Sensitivity to the aforementioned model inputs was also investigated. CO retrievals were shown to be most sensitive to the ILS (a function of the assumed instrument field-of-view, which is due to the narrow nature of CO absorption lines and their consequent sensitivity to convolution with the ILS. Conversely, CO2 retrievals were most sensitive to assumed atmospheric parameters, particularly gas temperature. Our findings provide confidence that FTIR-derived trace gas retrievals of CO2, CH4 and CO

  5. Fluid geochemistry and soil gas fluxes (CO2-CH4-H2S) at a promissory Hot Dry Rock Geothermal System: The Acoculco caldera, Mexico

    Science.gov (United States)

    Peiffer, L.; Bernard-Romero, R.; Mazot, A.; Taran, Y. A.; Guevara, M.; Santoyo, E.

    2014-09-01

    The Acoculco caldera has been recognized by the Mexican Federal Electricity Company (CFE) as a Hot Dry Rock Geothermal System (HDR) and could be a potential candidate for developing an Enhanced Geothermal System (EGS). Apart from hydrothermally altered rocks, geothermal manifestations within the Acoculco caldera are scarce. Close to ambient temperature bubbling springs and soil degassing are reported inside the caldera while a few springs discharge warm water on the periphery of the caldera. In this study, we infer the origin of fluids and we characterize for the first time the soil degassing dynamic. Chemical and isotopic (δ18O-δD) analyses of spring waters indicate a meteoric origin and the dissolution of CO2 and H2S gases, while gas chemical and isotopic compositions (N2/He, 3He/4He, 13C, 15N) reveal a magmatic contribution with both MORB- and arc-type signatures which could be explained by an extension regime created by local and regional fault systems. Gas geothermometry results are in agreement with temperature measured during well drilling (260 °C-300 °C). Absence of well-developed water reservoir at depth impedes re-equilibration of gases upon surface. A multi-gas flux survey including CO2, CH4 and H2S measurements was performed within the caldera. Using the graphical statistical analysis (GSA) approach, CO2 flux measurements were classified in two populations. Population A, representing 95% of measured fluxes is characterized by low values (mean: 18 g m- 2 day- 1) while the remaining 5% fluxes belonging to Population B are much higher (mean: 5543 g m- 2 day- 1). This low degassing rate probably reflects the low permeability of the system, a consequence of the intense hydrothermal alteration observed in the upper 800 m of volcanic rocks. An attempt to interpret the origin and transport mechanism of these fluxes is proposed by means of flux ratios as well as by numerical modeling. Measurements with CO2/CH4 and CO2/H2S flux ratios similar to mass ratios

  6. Technical Note: Latitude-time variations of atmospheric column-average dry air mole fractions of CO2, CH4 and N2O

    Directory of Open Access Journals (Sweden)

    M. Rettinger

    2012-08-01

    Full Text Available We present a comparison of an atmospheric general circulation model (AGCM-based chemistry-transport model (ACTM simulation with total column measurements of CO2, CH4 and N2O from the Total Carbon Column Observing Network (TCCON. The model is able to capture observed trends, seasonal cycles and inter hemispheric gradients at most sampled locations for all three species. The model-observation agreements are best for CO2, because the simulation uses fossil fuel inventories and an inverse model estimate of non-fossil fuel fluxes. The ACTM captures much of the observed seasonal variability in CO2 and N2O total columns (~81 % variance, R>0.9 between ACTM and TCCON for 19 out of 22 cases. These results suggest that the transport processes in troposphere and stratosphere are well represented in ACTM. Thus the poor correlation between simulated and observed CH4 total columns, particularly at tropical and extra-tropical sites, have been attributed to the uncertainties in surface emissions and loss by hydroxyl radicals. While the upward-looking total column measurements of CO2 contains surface flux signals at various spatial and temporal scales, the N2O measurements are strongly affected by the concentration variations in the upper troposphere and stratosphere.

  7. AC plasma torch with a H2O/CO2/CH4 mix as the working gas for methane reforming

    Science.gov (United States)

    Rutberg, Ph G.; Nakonechny, Gh V.; Pavlov, A. V.; Popov, S. D.; Serba, E. O.; Surov, A. V.

    2015-06-01

    This paper presents results of investigations implemented during construction of the three-phase ac plasma torch working on a mixture of steam with carbon dioxide and methane (H2O/CO2/CH4) with power upto 120 kW. Such thermal plasma generators are needed in industrial technologies for methane reforming with the aim of producing the syngas comprising of the hydrogen and carbon mono-oxide (H2/CO). It was shown that during plasma torch work there are two character parts of the high-voltage arc. In these parts, the arc column has a different diameter and temperature about (8.5  -  8.3) · 103 K and (10.5  -  10.0) · 103 K, respectively. The plasma torch output characteristics have been obtained for working regimes with various flow rates of the methane (0.0-0.8 g s-1) in the plasma-forming mix and constant flow rates of the carbon dioxide and water steam (each of 3.0 g s-1). For the mentioned mix of gases, the unit generates plasma with the mass-average temperature ~(3.2-3.3) · 103K and the thermal efficiency ~94-96%. This provides effective reforming of methane.

  8. Transport and transformation of soil-derived CO2, CH4 and DOC sustain CO2 supersaturation in small boreal streams.

    Science.gov (United States)

    Rasilo, Terhi; Hutchins, Ryan H S; Ruiz-González, Clara; Del Giorgio, Paul A

    2017-02-01

    Streams are typically supersaturated in carbon dioxide (CO2) and methane (CH4), and are recognized as important components of regional carbon (C) emissions in northern landscapes. Whereas there is consensus that in most of the systems the CO2 emitted by streams represents C fixed in the terrestrial ecosystem, the pathways delivering this C to streams are still not well understood. We assessed the contribution of direct soil CO2 injection versus the oxidation of soil-derived dissolved organic C (DOC) and CH4 in supporting CO2 supersaturation in boreal streams in Québec. We measured the concentrations of CO2, CH4 and DOC in 43 streams and adjacent soil waters during summer base-flow period. A mass balance approach revealed that all three pathways are significant, and that the mineralization of soil-derived DOC and CH4 accounted for most of the estimated stream CO2 emissions (average 75% and 10%, respectively), and that these estimated contributions did not change significantly between the studied low order (≤3) streams. Whereas some of these transformations take place in the channel proper, our results suggest that they mainly occur in the hyporheic zones of the streams. Our results further show that stream CH4 emissions can be fully explained by soil CH4 inputs. This study confirms that these boreal streams, and in particular their hyporheic zones, are extremely active processors of soil derived DOC and CH4, not just vents for soil produced CO2. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. A 156 kyr smoothed history of the atmospheric greenhouse gases CO2, CH4, and N2O and their radiative forcing

    Science.gov (United States)

    Köhler, Peter; Nehrbass-Ahles, Christoph; Schmitt, Jochen; Stocker, Thomas F.; Fischer, Hubertus

    2017-06-01

    Continuous records of the atmospheric greenhouse gases (GHGs) CO2, CH4, and N2O are necessary input data for transient climate simulations, and their associated radiative forcing represents important components in analyses of climate sensitivity and feedbacks. Since the available data from ice cores are discontinuous and partly ambiguous, a well-documented decision process during data compilation followed by some interpolating post-processing is necessary to obtain those desired time series. Here, we document our best possible data compilation of published ice core records and recent measurements on firn air and atmospheric samples spanning the interval from the penultimate glacial maximum ( ˜ 156 kyr BP) to the beginning of the year 2016 CE. We use the most recent age scales for the ice core data and apply a smoothing spline method to translate the discrete and irregularly spaced data points into continuous time series. These splines are then used to compute the radiative forcing for each GHG using well-established, simple formulations. We compile only a Southern Hemisphere record of CH4 and discuss how much larger a Northern Hemisphere or global CH4 record might have been due to its interpolar difference. The uncertainties of the individual data points are considered in the spline procedure. Based on the given data resolution, time-dependent cutoff periods of the spline, defining the degree of smoothing, are prescribed, ranging from 5000 years for the less resolved older parts of the records to 4 years for the densely sampled recent years. The computed splines seamlessly describe the GHG evolution on orbital and millennial timescales for glacial and glacial-interglacial variations and on centennial and decadal timescales for anthropogenic times. Data connected with this paper, including raw data and final splines, are available at doi:10.1594/PANGAEA.871273.

  10. A single gas chromatograph for accurate atmospheric mixing ratio measurements of CO2, CH4, N2O, SF6 and CO

    Directory of Open Access Journals (Sweden)

    H. A. J. Meijer

    2009-09-01

    Full Text Available We present an adapted gas chromatograph capable of measuring simultaneously and semi-continuously the atmospheric mixing ratios of the greenhouse gases CO2, CH4, N2O and SF6 and the trace gas CO with high precision and long-term stability. The novelty of our design is that all species are measured with only one device, making it a very cost-efficient system. No time lags are introduced between the measured mixing ratios. The system is designed to operate fully autonomously which makes it ideal for measurements at remote and unmanned stations. Only a small amount of sample air is needed, which makes this system also highly suitable for flask air measurements. In principle, only two reference cylinders are needed for daily operation and only one calibration per year against international WMO standards is sufficient to obtain high measurement precision and accuracy. The system described in this paper is in use since May 2006 at our atmospheric measurement site Lutjewad near Groningen, The Netherlands at 6°21´ E, 53°24´N, 1 m a.s.l. Results show the long-term stability of the system. Observed measurement precisions at our remote research station Lutjewad were: ±0.04 ppm for CO2, ±0.8 ppb for CH4, ±0.8 ppb for CO, ±0.3 ppb for N2O, and ±0.1 ppt for SF6. The ambient mixing ratios of all measured species as observed at station Lutjewad for the period of May 2007 to August 2008 are presented as well.

  11. True eddy accumulation and eddy covariance methods and instruments intercomparison for fluxes of CO2, CH4 and H2O above the Hainich Forest

    Science.gov (United States)

    Siebicke, Lukas

    2017-04-01

    The eddy covariance (EC) method is state-of-the-art in directly measuring vegetation-atmosphere exchange of CO2 and H2O at ecosystem scale. However, the EC method is currently limited to a small number of atmospheric tracers by the lack of suitable fast-response analyzers or poor signal-to-noise ratios. High resource and power demands may further restrict the number of spatial sampling points. True eddy accumulation (TEA) is an alternative method for direct and continuous flux observations. Key advantages are the applicability to a wider range of air constituents such as greenhouse gases, isotopes, volatile organic compounds and aerosols using slow-response analyzers. In contrast to relaxed eddy accumulation (REA), true eddy accumulation (Desjardins, 1977) has the advantage of being a direct method which does not require proxies. True Eddy Accumulation has the potential to overcome above mentioned limitations of eddy covariance but has hardly ever been successfully demonstrated in practice in the past. This study presents flux measurements using an innovative approach to true eddy accumulation by directly, continuously and automatically measuring trace gas fluxes using a flow-through system. We merge high-frequency flux contributions from TEA with low-frequency covariances from the same sensors. We show flux measurements of CO2, CH4 and H2O by TEA and EC above an old-growth forest at the ICOS flux tower site "Hainich" (DE-Hai). We compare and evaluate the performance of the two direct turbulent flux measurement methods eddy covariance and true eddy accumulation using side-by-side trace gas flux observations. We further compare performance of seven instrument complexes, i.e. combinations of sonic anemometers and trace gas analyzers. We compare gas analyzers types of open-path, enclosed-path and closed-path design. We further differentiate data from two gas analysis technologies: infrared gas analysis (IRGA) and laser spectrometry (open path and CRDS closed

  12. Effects of hydroxyl-functionalization and sub-Tg thermal annealing on high pressure pure- and mixed-gas CO2/CH4 separation by polyimide membranes based on 6FDA and triptycene-containing dianhydrides

    KAUST Repository

    Swaidan, Raja

    2015-02-01

    A sub-Tg thermally-annealed (250°C, 24h) ultra-microporous PIM-polyimide bearing a 9,10-diisopropyl-triptycene contortion center and hydroxyl-functionalized diamine (2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, APAF) exhibited plasticization resistance up to 50bar for a 1:1 CO2/CH4 feed mixture, with a 9-fold higher CO2 permeability (30Barrer) and 2-fold increase in CO2/CH4 permselectivity (~50) over conventional dense cellulose acetate membranes at 10bar CO2 partial pressure. Interestingly, mixed-gas CO2/CH4 permselectivities were 10-20% higher than those evaluated under pure-gas conditions due to reduction of mixed-gas CH4 permeability by co-permeation of CO2. Gas transport, physisorption and fluorescence studies indicated a sieving pore-structure engaged in inter-chain charge transfer complexes (CTCs), similar to that of low-free-volume 6FDA-APAF polyimide. The isosteric heat of adsorption of CO2 as well as CO2/CH4 solubility selectivities varied negligibly upon replacement of OH with CH3 but CTC formation was hindered, CO2 sorption increased, CO2 permeability increased ~3-fold, CO2/CH4 permselectivity dropped to ~30 and CH4 mixed-gas co-permeation increased. These results suggest that hydroxyl-functionalization did not cause preferential polymer-gas interactions but primarily elicited diffusion-dominated changes owing to a tightened microstructure more resistant to CO2-induced dilations. Solution-processable hydroxyl-functionalized PIM-type polyimides provide a new platform of advanced materials that unites the high selectivities of low-free-volume polymers with the high permeabilities of PIM-type materials particularly for natural gas sweetening applications.

  13. Soil CO2 CH4 and N2O fluxes from an afforested lowland raised peatbog in Scotland: implications for drainage and restoration

    Directory of Open Access Journals (Sweden)

    J. I. L. Morison

    2013-02-01

    Full Text Available The effect of tree (lodgepole pine planting with and without intensive drainage on soil greenhouse gas (GHG fluxes was assessed after 45 yr at a raised peatbog in West Flanders Moss, central Scotland. Fluxes of CO2 CH4 and N2O from the soil were monitored over a 2-yr period every 2 to 4 weeks using the static opaque chamber method in a randomised experimental block trial with the following treatments: drained and planted (DP, undrained and planted (uDP, undrained and unplanted (uDuP and for reference also from an adjoining near-pristine area of bog at East Flanders Moss (n-pris. There was a strong seasonal pattern in both CO2 and CH4 effluxes which were significantly higher in late spring and summer months because of warmer temperatures. Effluxes of N2O were low and no significant differences were observed between the treatments. Annual CH4 emissions increased with the proximity of the water table to the soil surface across treatments in the order: DP 4 m−2 yr−1, respectively. For CO2, effluxes increased in the order uDP 2 m−2 yr−1, respectively. CO2 effluxes dominated the total net GHG emission, calculated using the global warming potential (GWP of the three GHGs for each treatment (76–98%, and only in the n-pris site was CH4 a substantial contribution (23%. Based on soil effluxes only, the near pristine (n-pris peatbog had 43% higher total net GHG emission compared with the DP treatment because of high CH4 effluxes and the DP treatment had 33% higher total net emission compared with the uDP because drainage increased CO2 effluxes. Restoration is likely to increase CH4 emissions, but reduce CO2 effluxes. Our study suggests that if estimates of CO2 uptake by vegetation from similar peatbog sites were included, the total net GHG emission of restored peatbog would still be higher than that of the peatbog with trees.

  14. The IAGOS-core greenhouse gas package: a measurement system for continuous airborne observations of CO2, CH4, H2O and CO

    Directory of Open Access Journals (Sweden)

    Annette Filges

    2015-09-01

    flights and laboratory tests that document the performance for CO2, CH4, CO and water vapour measurements.

  15. CO2, CH4 and N2O fluxes in an Ultisol treated with sewage sludge and cultivated with castor bean Fluxos de CO2, CH4 e N2O de um Argissolo tratado com lodo de esgoto e cultivado com mamona

    Directory of Open Access Journals (Sweden)

    Jonas Jacob Chiaradia

    2009-12-01

    Full Text Available Organic residue application into soil alter the emission of gases to atmosphere and CO2, CH4, N2O may contribute to increase the greenhouse effect. This experiment was carried out in a restoration area on a dystrophic Ultisol (PVAd to quantify greenhouse gas (GHG emissions from soil under castor bean cultivation, treated with sewage sludge (SS or mineral fertilizer. The following treatments were tested: control without N; FertMin = mineral fertilizer; SS5 = 5 t ha-1 SS (37.5 kg ha-1 N; SS10 = 10 t ha-1 SS (75 kg ha-1 N; and SS20 = 20 t ha-1 SS (150 kg ha-1 N. The amount of sludge was based on the recommended rate of N for castor bean (75 kg ha-1, the N level of SS and the mineralization fraction of N from SS. Soil gas emission was measured for 21 days. Sewage sludge and mineral fertilizers altered the CO2, CH4 and N2O fluxes. Soil moisture had no effect on GHG emissions and the gas fluxes was statistically equivalent after the application of FertMin and of 5 t ha-1 SS. The application of the entire crop N requirement in the form of SS practically doubled the Global Warming Potential (GWP and the C equivalent emissions in comparison with FertMin treatments.A aplicação de resíduos orgânicos no solo pode alterar a emissão de gases para atmosfera e dentre estes, CO2, CH4 e N2O, podem contribuir para o aumento do efeito estufa. Este ensaio foi realizado com o objetivo de quantificar a emissão de gases do efeito estufa (GEE de um Argissolo Vermelho-Amarelo distrófico (PVAd tratado com lodo de esgoto (LE e cultivado com mamoneira em área de reforma de canavial. Os tratamentos testados foram: Controle sem N; FertMin = fertilizante mineral; LE5 = 5 t ha-1 de LE, equivalente a 37,5 kg ha-1 de N; LE10 = 10 t ha-1 de LE, equivalente a 75 kg ha-1 de N; e LE20 = 20 t ha-1 de LE, equivalente a 150 kg ha-1 de N. A quantidade de lodo foi baseada na rate recomendada de N para a mamoneira (75 kg ha-1, nas quantidades de N no LE e na fração de mineraliza

  16. Fluxes of CO2, CH4 and N2O at two European beech forests: linking soil gas production profiles with soil and stem fluxes

    Science.gov (United States)

    Maier, Martin; Machacova, Katerina; Halaburt, Ellen; Haddad, Sally; Urban, Otmar; Lang, Friederike

    2016-04-01

    Soil and plant surfaces are known to exchange greenhouse gases with the atmosphere. Some gases like nitrous oxide (N2O) and methane (CH4) can be produced and re-consumed in different soil depths and soil compartments, so that elevated concentrations of CH4 or N2O in the soil do not necessarily mean a net efflux from the soil into the atmosphere. Soil aeration, and thus the oxygen status can underlay a large spatial variability within the soil on the plot and profile scale, but also within soil aggregates. Thus, conditions suitable for production and consumption of CH4 and N2O can vary on different scales in the soil. Plant surfaces can also emit or take up CH4 and N2O, and these fluxes can significantly contribute to the net ecosystem exchange. Since roots usually have large intercellular spaces or aerenchyma they may represent preferential transport ways for soil gases, linking possibly elevated soil gas concentrations in the subsoil in a "shortcut" to the atmosphere. We tested the hypothesis that the spatial variability of the soil-atmosphere fluxes of CO2, CH4 and N2O is caused by the heterogeneity in soil properties. Therefore, we measured soil-atmosphere gas fluxes, soil gas concentrations and soil diffusivity profiles and did a small scale field assessment of soil profiles on the measurments plots. We further tried to link vertical profiles of soil gas concentrations and diffusivity to derive the production and consumption profiles, and to link these profiles to the stem-atmosphere flux rates of individual trees. Measurements were conducted in two mountain beech forests with different geographical and climatic conditions (White Carpathians, Czech Republic; Black Forest, Germany). Gas fluxes at stem and soil levels were measured simultaneously using static chamber systems and chromatographic and continuous laser analyses. Monitoring simultaneously vertical soil gas profiles allowed to assess the within-soil gas fluxes, and thus to localize the production and

  17. High pressure pure- and mixed-gas separation of CO2/CH4 by thermally-rearranged and carbon molecular sieve membranes derived from a polyimide of intrinsic microporosity

    KAUST Repository

    Swaidan, Raja

    2013-11-01

    Natural gas sweetening, one of the most promising venues for the growth of the membrane gas separation industry, is dominated by polymeric materials with relatively low permeabilities and moderate selectivities. One strategy towards improving the gas transport properties of a polymer is enhancement of microporosity either by design of polymers of intrinsic microporosity (PIMs) or by thermal treatment of polymeric precursors. For the first time, the mixed-gas CO2/CH4 transport properties are investigated for a complete series of thermally-rearranged (TR) (440°C) and carbon molecular sieve (CMS) membranes (600, 630 and 800°C) derived from a polyimide of intrinsic microporosity (PIM-6FDA-OH). The pressure dependence of permeability and selectivity is reported up to 30bar for 1:1, CO2:CH4 mixed-gas feeds at 35°C. The TR membrane exhibited ~15% higher CO2/CH4 selectivity relative to pure-gas feeds due to reductions in mixed-gas CH4 permeability reaching 27% at 30bar. This is attributed to increased hindrance of CH4 transport by co-permeation of CO2. Interestingly, unusual increases in mixed-gas CH4 permeabilities relative to pure-gas values were observed for the CMS membranes, resulting in up to 50% losses in mixed-gas selectivity over the applied pressure range. © 2013 Elsevier B.V.

  18. Distribution of dissolved green-house gases (CO2, CH4, N2O) in Lakes Edward and George: Results from the first field cruise of the HIPE project

    Science.gov (United States)

    Borges, Alberto V.; Morana, Cédric D. T.; Lambert, Thibault; Okello, William; Bouillon, Steven

    2017-04-01

    Inland waters (streams, rivers, lakes, reservoirs) are quantitatively important components of the global budgets of atmospheric emissions of long-lived greenhouse gases (GHGs) (CO2, CH4, N2O). Available data indicate that a very large fraction of CO2 and CH4 emissions from rivers and reservoirs occurs at tropical latitudes. Data on GHGs at tropical latitudes from lakes however are much more scarse, and the relative importance of emissions, in particular in Africa, remains to be determined. Large tropical lakes are net autotrophic (hence potentially sinks for atmospheric CO2) due generally low dissolved organic carbon concentrations, seasonally near constant light and temperature conditions, and generally deep water columns favourable for export of organic matter to depth. This sharply contrasts with their much better documented temperate and boreal counterparts, usually considered as CO2 sources to the atmosphere sustained by net heterotrophy. Here, we report a data-set of dissolved CO2, CH4, N2O obtained in October 2016 in Lakes Edward and George and adjacent streams and crater lakes in the frame of Belgian Science Policy (BELSPO) HIPE (Human impacts on ecosystem health and resources of Lake Edward, http://www.co2.ulg.ac.be/hipe/) project. Lake George and part of Lake Edward were sinks for atmospheric CO2 and N2O due to high primary production and denitrification in sediments, respectively, and modest sources of CH4 to the atmosphere. Sampled rivers and streams were oversaturated in CO2 and CH4 and close to atmospheric equilibrium with regards to N2O. Spatial variations within rivers and streams were related to elevation and vegetation characteristics on the catchments (savannah versus forest). Levels of CO2, CH4, and N2O were within the range of those we reported in other African rivers. Crater lakes acted as sinks for atmospheric CO2 and N2O but were extremely over-saturated in CH4, due to intense primary production sustained by cyanobacteria. These CH4 levels

  19. A microporous MOF with a polar pore surface exhibiting excellent selective adsorption of CO2 from CO2-N2 and CO2-CH4 gas mixtures with high CO2 loading.

    Science.gov (United States)

    Pal, Arun; Chand, Santanu; Elahi, Syed Meheboob; Das, Madhab C

    2017-10-25

    A microporous MOF {[Zn(SDB)(L)0.5]·S}n (IITKGP-5) with a polar pore surface has been constructed by the combination of a V-shaped -SO2 functionalized organic linker (H2SDB = 4,4'-sulfonyldibenzoic acid) with an N-rich spacer (L = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene), forming a network with sql(2,6L1) topology. IITKGP-5 is characterized by TGA, PXRD and single crystal X-ray diffraction. The framework exhibits lozenge-shaped channels of an approximate size of 4.2 × 5.6 Å(2) along the crystallographic b axis with a potential solvent accessible volume of 26%. The activated IITKGP-5a revealed a CO2 uptake capacity of 56.4 and 49 cm(3) g(-1) at 273 K/1 atm and 295 K/1 atm, respectively. On the contrary, it takes up a much smaller amount of CH4 (17 cm(3) g(-1) at 273 K and 13.6 cm(3) g(-1) at 295 K) and N2 (5.5 cm(3) g(-1) at 273 K; 4 cm(3) g(-1) at 295 K) under 1 atm pressure exhibiting its potential for a highly selective adsorption of CO2 from flue gas as well as a landfill gas mixture. Based on the ideal adsorbed solution theory (IAST), a CO2/N2 selectivity of 435.5 and a CO2/CH4 selectivity of 151.6 have been realized at 273 K/100 kPa. The values at 295 K are 147.8 for CO2/N2 and 23.8 for CO2/CH4 gas mixtures under 100 kPa. In addition, this MOF nearly approaches the target values proposed for PSA and TSA processes for practical utility exhibiting its prospect for flue gas separation with a CO2 loading capacity of 2.04 mmol g(-1).

  20. Continuous multi-plot measurements of CO2, CH4, N2O and H2O in a managed boreal forest - The importance of accounting for all greenhouse gases

    Science.gov (United States)

    Vestin, P.; Mölder, M.; Sundqvist, E.; Båth, A.; Lehner, I.; Weslien, P.; Klemedtsson, L.; Lindroth, A.

    2015-12-01

    In order to assess the effects of different management practices on the exchange of greenhouse gases (GHG), it is desirable to perform repeated and parallel measurements on both experimental and control plots. Here we demonstrate how a system system combining eddy covariance and gradient techniques can be used to perform this assessment in a managed forest ecosystem.The net effects of clear-cutting and stump harvesting on GHG fluxes were studied at the ICOS site Norunda, Sweden. Micrometeorological measurements (i.e., flux-gradient measurements in 3 m tall towers) allowed for quantification of CO2, CH4 and H2O fluxes (from May 2010) as well as N2O and H2O fluxes (from June 2011) at two stump harvested plots and two control plots. There was one wetter and one drier plot of each treatment. Air was continuously sampled at two heights in the towers and gas concentrations were analyzed for CH4, CO2, H2O (LGR DLT-100, Los Gatos Research) and N2O, H2O (QCL Mini Monitor, Aerodyne Research). Friction velocities and sensible heat fluxes were measured by sonic anemometers (Gill Windmaster, Gill Instruments Ltd). Automatic chamber measurements (CO2, CH4, H2O) were carried out in the adjacent forest stand and at the clear-cut during 2010.Average CO2 emissions for the first year ranged between 14.4-20.2 ton CO2 ha-1 yr-1. The clear-cut became waterlogged after harvest and a comparison of flux-gradient data and chamber data (from the adjacent forest stand) indicated a switch from a weak CH4 sink to a significant source at all plots. The CH4 emissions ranged between 0.8-4.5 ton CO2-eq. ha-1 yr-1. N2O emissions ranged between 0.4-2.6 ton CO2-eq. ha-1 yr-1. Enhanced N2O emission on the drier stump harvested plot was the only clear treatment effect on GHG fluxes that was observed. Mean CH4 and N2O emissions for the first year of measurements amounted up to 29% and 20% of the mean annual CO2 emissions, respectively. This highlights the importance of including all GHGs when assessing

  1. Characterization of trace gases measured over Alberta oil sands mining operations: 76 speciated C2-C10 volatile organic compounds (VOCs), CO2, CH4, CO, NO, NO2, NOy, O3 and SO2

    Science.gov (United States)

    Simpson, I. J.; Blake, N. J.; Barletta, B.; Diskin, G. S.; Fuelberg, H. E.; Gorham, K.; Huey, L. G.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Yang, M.; Blake, D. R.

    2010-12-01

    Oil sands comprise 30% of the world's oil reserves and the crude oil reserves in Canada's oil sands deposits are second only to Saudi Arabia. The extraction and processing of oil sands is much more challenging than for light sweet crude oils because of the high viscosity of the bitumen contained within the oil sands and because the bitumen is mixed with sand and contains chemical impurities such as sulphur. Despite these challenges, the importance of oil sands is increasing in the energy market. To our best knowledge this is the first peer-reviewed study to characterize volatile organic compounds (VOCs) emitted from Alberta's oil sands mining sites. We present high-precision gas chromatography measurements of 76 speciated C2-C10 VOCs (alkanes, alkenes, alkynes, cycloalkanes, aromatics, monoterpenes, oxygenated hydrocarbons, halocarbons and sulphur compounds) in 17 boundary layer air samples collected over surface mining operations in northeast Alberta on 10 July 2008, using the NASA DC-8 airborne laboratory as a research platform. In addition to the VOCs, we present simultaneous measurements of CO2, CH4, CO, NO, NO2, NOy, O3 and SO2, which were measured in situ aboard the DC-8. Carbon dioxide, CH4, CO, NO, NO2, NOy, SO2 and 53 VOCs (e.g., non-methane hydrocarbons, halocarbons, sulphur species) showed clear statistical enhancements (1.1-397×) over the oil sands compared to local background values and, with the exception of CO, were greater over the oil sands than at any other time during the flight. Twenty halocarbons (e.g., CFCs, HFCs, halons, brominated species) either were not enhanced or were minimally enhanced (coke combustion. By contrast, relatively poor correlations between CH4, ethane and propane suggest low levels of natural gas leakage despite its heavy use at the surface mining sites. Instead the elevated CH4 levels are attributed to methanogenic tailings pond emissions. In addition to the emission of many trace gases, the natural drawdown of OCS by

  2. Diverse melanges of an ancient subduction complex

    Energy Technology Data Exchange (ETDEWEB)

    Lash, G.G.

    1987-07-01

    Three lithologically and structurally diverse melanges occur within an early Paleozoic (Early-Middle Ordovician) subduction complex in the central Appalachian orogen. Type I melange, characterized by horizons of variably deformed sandstone and scaly mudstone that alternate with coherent sandstone-rich sequences, is interpreted to reflect accretion-related deformation of water-saturated trench deposits. Type II melange, composed of exotic radiolaria-bearing mudstone clasts in a scaly mudstone matrix, can be explained by remobilization and mixing of inner-trench slope sediments. Type III melange is a poorly sorted polymict assemblage of native lithology clasts in a scaly mudstone matrix. Evidence of forceful injection of matrix mud into clasts and inferred discordant contacts between melange and surrounding bedded deposits suggest that the type III melange formed from mud diapirism. The close association of these melanges points out the diversity of tectonic and sedimentary processes previously documented from modern convergent margins that may be reflected in older subduction complexes.

  3. Strain development in unconfined coals exposed to CO2, CH4 and Ar: Effect of moisture

    NARCIS (Netherlands)

    Bergen, F. van; Spiers, C.; Floor, G.; Bots, P.

    2009-01-01

    Field experiments and laboratory studies have shown that swelling of coal takes place upon contact with carbon dioxide at underground pressure and temperature conditions. Understanding this swelling behavior is crucial for predicting the performance of future carbon dioxide sequestration operations

  4. Hindering effects in diffusion of CO2/CH4 mixtures in ZIF-8 crystals

    NARCIS (Netherlands)

    Chmelik, C.; van Baten, J.; Krishna, R.

    2012-01-01

    Cage-type micro-porous materials such as LTA, CHA, SAPO-34, DDR, ERI, ZIF-7, and ZIF-8 have significant potential for use in membrane technologies for CO2 capture. The permeation selectivities are governed by a combination of adsorption and diffusion selectivities, each of which can be separately

  5. Adsorptive separation of CO2/CH4/CO gas mixtures at high pressures

    NARCIS (Netherlands)

    Krishna, R.

    2012-01-01

    The major objective of this communication is to compare the performance of three metal-organic frameworks (MOFs): CuBTC, MIL-101, and Zn(bdc)dabco, with that of NaX zeolite for selective adsorption of CO2 from mixtures containing CH4 and CO in a pressure swing adsorption (PSA) unit operating at

  6. Quantum and gravity. Blend or melange?

    Energy Technology Data Exchange (ETDEWEB)

    Wuethrich, Christian [University of Geneva (Switzerland)

    2016-07-01

    Do we need to quantize gravity, as it is tacitly assumed in much of fundamental physics? The standard lore falls short of justifying an affirmative answer. Black hole thermodynamics is widely considered, faint though it may be, our firmest hint at a quantum theory of gravity - despite the failure to date to observe Hawking radiation or any other effect that would require going beyond a classical description of black holes. Hawking radiation hitherto merely enjoys a theoretical derivation in a semi-classical theory combining quantum matter with classical gravity. But how can a semi-classical melange of physical principles possibly justify that the quantum and gravity are blended into a unified fundamental theory when the latter is generally expected to reject at least some of the principles in the former?.

  7. New Yorker Melange: Interactive Brew of Personalized Venue Recommendation

    NARCIS (Netherlands)

    Zahálka, J.; Rudinac, S.; Worring, M.

    2014-01-01

    In this paper we propose New Yorker Melange, an interactive city explorer, which navigates New York venues through the eyes of New Yorkers having a similar taste to the interacting user. To gain insight into New Yorkers' preferences and properties of the venues, a dataset of more than a million

  8. Temporal and spatial variations of soil CO2, CH4 and N2O fluxes at three differently managed grasslands

    Directory of Open Access Journals (Sweden)

    D. Imer

    2013-09-01

    Full Text Available A profound understanding of temporal and spatial variabilities of soil carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three soil greenhouse gas (GHG fluxes occur due to changes in environmental drivers as well as fertilizer applications, harvests and grazing. To assess how such changes affect soil GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed to 1000 m a.s.l. (moderately intensive managed to 2000 m a.s.l. (extensively managed. The alpine grassland was included to study both effects of extensive management on CH4 and N2O fluxes and the different climate regime occurring at this altitude. Temporal and spatial variabilities of soil GHG fluxes and environmental drivers on various timescales were determined along transects of 16 static soil chambers at each site. All three grasslands were N2O sources, with mean annual soil fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were weak CH4 sinks, with soil uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual soil and plant respiration losses of CO2, measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for soil N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42, CH4 and CO2 soil fluxes were much better constrained (adjusted r2 ranging from 0.46 to 0.80 by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for soil N2O and CH4 fluxes. We found permanent hot spots for soil N2O emissions as well as locations of permanently lower soil CH4 uptake rates at the extensively managed alpine site. Including hot spots was essential to obtain a representative mean soil flux for the respective ecosystem. At the intensively managed grassland, management effects clearly dominated over effects of environmental drivers on soil N2O fluxes. For CO2 and CH4, the importance of management effects did depend on the status of the vegetation (LAI.

  9. Effect of solvents on the morphology and performance of Polyethersulfone (PES) polymeric membranes material for CO2/CH4 separation

    Science.gov (United States)

    Ahmad, M. S.; Mohshim, D. F.; Nasir, R.; Mannan, H. A.; Mukhtar, H.

    2018-01-01

    Membrane technology has several advantages such as the ability to separate chemical species within compact plant footprints, low thermal energy requirements and simple process flow schemes. By optimizing the available materials and analysis, this work comes with the objective to synthesize the polymeric membrane, which has the best separation performance. In this work, three (03) membranes have been synthesized and a comparative analysis were conducted based on different types of solvent namely N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidinone (NMP). In characterizing the synthesized membrane, Thermo Gravimetric Analysis (TGA), Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis were used. A comparative study was carried out to compare the effects of each solvent towards CO2 separation performance.

  10. Zeolite Rho: a highly selective adsorbent for CO2/CH4 separation induced by a structural phase modification.

    Science.gov (United States)

    Palomino, Miguel; Corma, Avelino; Jordá, Jose L; Rey, Fernando; Valencia, Susana

    2012-01-07

    Zeolite Rho is able to successfully separate CO(2) from CH(4) with the highest selectivity ever observed on the basis of pore diameter and surface polarity. The adsorption of CO(2) provokes structural changes in the zeolite Rho. This journal is © The Royal Society of Chemistry 2012

  11. Tailoring the free volume of all-aromatic polyimide membranes for CO2/CH4 gas separation

    OpenAIRE

    Madzarevic, Z.

    2017-01-01

    Efficient and cost-effective technologies that will enable separation and capture of CO2 are needed. The development of high-performance all-aromatic poly(ether)imide (P(E)I) membranes is attractive as they offer a large degree of design freedom and they are cheap to operate. However, the molecular design rules towards P(E)I membranes that exhibit high selectivity and high permeability with no or little CO2 plasticization are still largely unknown. The main objective of the research presented...

  12. Tree species influence soil-atmosphere fluxes of the greenhouse gases CO2, CH4 and N2O

    Science.gov (United States)

    Steffens, Christina; Vesterdal, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    In the temperate zone, forests are the greatest terrestrial sink for atmospheric CO2, and tree species affect soil C stocks and soil CO2 emissions. When considering the total greenhouse gas (GHG) balance of the forest soil, the relevant GHGs CH4 and N2O should also be considered as they have a higher global warming potential than CO2. The presented data are first results from a field study in a common garden site in Denmark where tree species with ectomycorrhizal colonization (beech - Fagus sylvatica, oak - Quercus robur) and with arbuscular mycorrhizal colonization (maple - Acer pseudoplatanus, ash - Fraxinus excelsior) have been planted in monocultures in adjacent blocks of about 0.25 ha in the year 1973 on former arable land. The soil-atmosphere fluxes of all three gases were measured every second week since August 2015. The hypothesis is that the total GHG efflux from forest soil would differ between species, and that these differences could be related to the type of mycorrhizal association and leaf litter quality. Preliminary results (August to December 2015) indicate that tree species influence the fluxes (converted to CO2-eq) of the three GHGs. Total soil CO2 efflux was in the low end of the range reported for temperate broadleaved forests but similar to the measurements at the same site approximately ten years ago. It was highest under oak (9.6±2.4 g CO2 m-2 d-1) and lowest under maple (5.2±1.6 g CO2 m-2 d-1). In contrast, soil under oak was a small but significant sink for CH4(-0.005±0.003 g CO2-eq m-2 d-1), while there were almost no detectable CH4 fluxes in maple. Emissions of N2O were highest under beech (0.6±0.6 g CO2-eq m-2 d-1) and oak (0.2±0.09 g CO2-eq m-2 d-1) and lowest under ash (0.03±0.04 g CO2-eq m-2 d-1). In the total GHG balance, soil CH4 uptake was negligible (≤0.1% of total emissions). Emissions of N2O (converted to CO2-eq) contributed arbuscular mycorrhiza and produce leaf litter with a lower lignin:N ratio.

  13. Miniaturized Near Infrared Heterodyne Spectroradiometer for Monitoring CO2, CH4 and CO in the Earth Atmosphere

    Science.gov (United States)

    Klimchuk, A., Sr.; Rodin, A.; Nadezhdinskiy, A.; Churbanov, D.; Spiridonov, M.

    2014-12-01

    The paper describes the concept of a compact, lightweight heterodyne NIR spectro-radiometer suitable for atmospheric sounding with solar occultations, and the first measurement of CO2 and CH4 absorption near 1.60mm and 1.65 mm with spectral resolution l/dl ~ 5*107. Highly stabilized DFB laser was used as local oscillator, while single model quartz fiber Y-coupler served as a diplexer. Radiation mixed in the single mode fiber was detected by quadratic detector using p-i-n diode within the bandpass of ~10 MHz. Wavelength coverage of spectral measurement was provided by sweeping local oscillator frequency in the range 1,1 см-1. With the exposure time of 10 min, the absorption spectrum of the atmosphere over Moscow has been recorded with S/N ~ 300. We retrieved methane vertical profile using Tikhonov method of smooth functional, which takes into account a priori information about first guess profile. The reference to model methane profile means that the regularization procedure always selects a priorivalues unless the measurements contradict this assumption.The retrieved methane profile demonstrates higher abundances in the lower scale height compared to the assumed model profile, well expected in the megalopolis center. The retrievals sensitivity is limited by 10 ppb, with the exception of the lower part of the profile where the tendency to lower values is revealed. Thus the methane abundance variations may be evaluated with relative accuracy better than 1%, which fits the requirements of greenhouse gas monitoring. The retrievals sensitivity of CO2 is about 1-2 ppm. CO2 observations was also used to estimate stratoshere wind by doppler shift of absorption line. Due to higher spectral resolution, lower sensitivity to atmospheric temperatures and other external factors, compared to heterodyne measurements in the thermal IR spectral range, the described technique provides accuracy comparable with much more complicated high resolution measurements now used in TCCON stations. Relative simplicity of the proposed scheme opens a perspective to employ it for high resolution spectroscopy in various applications. In particular, it may allow solar occultation observations of CO2, CО, CH4, H2S, C2H4 and other gases from spacecraft, airborne or ground-based platforms.

  14. Tailoring the free volume of all-aromatic polyimide membranes for CO2/CH4 gas separation

    NARCIS (Netherlands)

    Madzarevic, Z.

    2017-01-01

    Efficient and cost-effective technologies that will enable separation and capture of CO2 are needed. The development of high-performance all-aromatic poly(ether)imide (P(E)I) membranes is attractive as they offer a large degree of design freedom and they are cheap to operate. However, the molecular

  15. Adsorption-induced deformation of microporous materials: coal swelling induced by CO2-CH4 competitive adsorption.

    Science.gov (United States)

    Brochard, Laurent; Vandamme, Matthieu; Pellenq, Roland J-M; Fen-Chong, Teddy

    2012-02-07

    Carbon dioxide injection in coal seams is known to improve the methane production of the coal seam, while ensuring a safe and long-term carbon sequestration. This improvement is due to the preferential adsorption of CO(2) in coal with respect to CH(4): an injection of CO(2) thus results in a desorption of CH(4). However, this preferential adsorption is also known to cause a differential swelling of coal, which results in a significant decrease in the reservoir permeability during the injection process. Recent studies have shown that adsorption in coal micropores (few angströms in size) is the main cause of the swelling. In this work, we focus on the competitive adsorption behavior of CO(2) and CH(4) in micropores. We perform molecular simulations of adsorption with a realistic atomistic model for coal. The competitive adsorption is studied at various temperatures and pressures representative of those in geological reservoirs. With the help of a poromechanical model, we then quantify the subsequent differential swelling induced by the computed adsorption behaviors. The differential swelling is almost insensitive to the geological temperatures and pressures considered here and is proportional to the CO(2) mole fraction in the coal.

  16. Integrated measurements and modeling of CO2, CH4, and N2O fluxes using soil microsite frequency distributions

    Science.gov (United States)

    Davidson, Eric; Sihi, Debjani; Savage, Kathleen

    2017-04-01

    Soil fluxes of greenhouse gases (GHGs) play a significant role as biotic feedbacks to climate change. Production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are affected by complex interactions of temperature, moisture, and substrate supply, which are further complicated by spatial heterogeneity of the soil matrix. Models of belowground processes of these GHGs should be internally consistent with respect to the biophysical processes of gaseous production, consumption, and transport within the soil, including the contrasting effects of oxygen (O2) as either substrate or inhibitor. We installed automated chambers to simultaneously measure soil fluxes of CO2 (using LiCor-IRGA), CH4, and N2O (using Aerodyne quantum cascade laser) along soil moisture gradients at the Howland Forest in Maine, USA. Measured fluxes of these GHGs were used to develop and validate a merged model. While originally intended for aerobic respiration, the core structure of the Dual Arrhenius and Michaelis-Menten (DAMM) model was modified by adding M-M and Arrhenius functions for each GHG production and consumption process, and then using the same diffusion functions for each GHG and for O2. The area under a soil chamber was partitioned according to a log-normal probability distribution function, where only a small fraction of microsites had high available-C. The probability distribution of soil C leads to a simulated distribution of heterotrophic respiration, which translates to a distribution of O2 consumption among microsites. Linking microsite consumption of O2 with a diffusion model generates microsite concentrations of O2, which then determine the distribution of microsite production and consumption of CH4 and N2O, and subsequently their microsite concentrations using the same diffusion function. At many moisture values, there are some microsites of production and some of consumption for each gas, and the resulting simulated microsite concentrations of CH4 and N2O range from below ambient to above ambient atmospheric values. As soil moisture or temperature increase, the skewness of the microsite distributions of heterotrophic respiration and CH4 concentrations shifts toward a larger fraction of high values, while the skewness of microsite distributions of O2 and N2O concentrations shifts toward a larger fraction of low values. This approach of probability distribution functions for each gas simulates the importance of microsite hotspots of methanogenesis and N2O reduction at high moisture (and temperature). In addition, the model demonstrates that net consumption of atmospheric CH4 and N2O can occur simultaneously within a chamber due to the distribution of soil microsite conditions, which is consistent with some episodes of measured fluxes. Because soil CO2, N2O and CH4 fluxes are linked through substrate supply and O2 effects, the multiple constraints of simultaneous measurements of all three GHGs proved to be effective when applied to our combined model. Simulating all three GHGs simultaneously in a parsimonious modeling framework provides confidence that the most important mechanisms are skillfully simulated using appropriate parameterization and good process representation.

  17. Tiber delta CO2-CH4 degassing: A possible hybrid, tectonically active Sediment-Hosted Geothermal System near Rome

    Science.gov (United States)

    Ciotoli, G.; Etiope, G.; Marra, F.; Florindo, F.; Giraudi, C.; Ruggiero, L.

    2016-01-01

    Fiumicino town in the Tiber River delta, near Rome International Airport (Italy), is historically affected by large amounts of carbon dioxide (CO2) in the ground and gas eruptions triggered by shallow drilling. While it is known that CO2 originates from carbonate thermometamorphism and/or mantle degassing, the origin of methane (CH4) associated with CO2 is uncertain and the outgassing spatial distribution is unknown. Combining isotope gas geochemistry, soil gas, and structural-stratigraphic analyses, we provide evidence for a hybrid fluid source system, classifiable as Sediment-Hosted Geothermal System (SHGS), where biotic CH4 from sedimentary rocks is carried by deep geothermic CO2 through active segments of a half-graben. Molecular and isotopic composition of CH4 and concentration of heavier alkanes (ethane and propane), obtained from gas vents and soil gas throughout the delta area, reveal that thermogenic CH4 (up to 3.7 vol% in soil gas; δ13CCH4: -37 to -40‰ VPDB-Vienna Peedee Belemnite, and δ2HCH4: -162 to -203‰ VSMOW - Vienna Standard Mean Ocean Water in gas vents) prevails over possible microbial and abiotic components. The hydrocarbons likely result from known Meso-Cenozoic petroleum systems of the Latium Tyrrhenian coast. Overmaturation of source rocks or molecular fractionation induced by gas migration are likely responsible for increased C1/C2+ ratios. CO2 and CH4 soil gas anomalies are scattered along NW-SE and W-E alignments, which, based on borehole, geomorphologic, and structural-stratigraphic analyses, coincide with active faults of a half-graben that seems to have controlled the recent evolution of the Tiber delta. This SHGS can be a source of considerable greenhouse gas emissions to the atmosphere and hazards for humans and buildings.

  18. Etude des melanges co-continus d'acide polylactique et d'amidon thermoplastique (PLA/TPS)

    Science.gov (United States)

    Chavez Garcia, Maria Graciela

    Les melanges co-continus sont des melanges polymeriques ou chaque composant se trouve dans une phase continue. Pour cette raison, les caracteristiques de chacun des composants se combinent et il en resulte un materiau avec une morphologie et des proprietes particulieres. L'acide polylactique (PLA) et l'amidon thermoplastique (TPS) sont des biopolymeres qui proviennent de ressources renouvelables et qui sont biodegradables. Dans ce projet, differents melanges de PLA et TPS a une haute concentration de TPS ont ete prepares dans une extrudeuse bi-vis afin de generer des structures co-continues. Grace a la technique de lixiviation selective, le TPS est enleve pour creer une structure poreuse de PLA qui a pu etre analysee au moyen de la microtomographie R-X et de la microscopie electronique a balayage MEB. L'analyse des images 2D et 3D confirme la presence de la structure co-continue dans les melanges dont la concentration en TPS. se situe entre 66% et 80%. L'effet de deux plastifiants, le glycerol seul et le melange de glycerol et de sorbitol, dans la formulation de TPS est etudie dans ce travail. De plus, nous avons evalue l'effet du PLA greffe a l'anhydride maleique (PLAg) en tant que compatibilisant. On a trouve que la phase de TPS obtenue avec le glycerol est plus grande. L'effet de recuit sur la taille de phases est aussi analyse. Grace aux memes techniques d'analyse, on a etudie l'effet du procede de moulage par injection sur la morphologie. On a constate que les pieces injectees presentent une microstructure heterogene et differente entre la surface et le centre de la piece. Pres de la surface, une peau plus riche en PLA est presente et les phases de TPS y sont allongees sous forme de lamelles. Plus au centre de la piece, une morphologie plus cellulaire est observee pour chaque phase continue. L'effet des formulations sur les proprietes mecaniques a aussi ete etudie. Les pieces injectees dont la concentration de TPS est plus grande presentent une moindre

  19. Estimating ice-melange properties with repeat UAV surveys over Store Glacier, West Greenland

    Science.gov (United States)

    Toberg, Nick; Ryan, Johnny; Christoffersen, Poul; Snooke, Neal; Todd, Joe; Hubbard, Alun

    2016-04-01

    In the past decade, tidewater outlet glaciers of the Greenland ice sheet (GrIS) have thinned and retreated when compared to the 1980s when the ice sheet was in a state of dynamic balance. With a growing amount of ice discharged into the sea by tidewater glaciers as well as more ice melting on the surface, the Greenland Ice Sheet has become the single largest cryospheric source of global sea level rise. Today, the ice sheet causes sea level rise of 1 mm per year, highlighting the need to understand the ice sheet's response to climate change. Atmospheric warming will inevitably continue to increase surface meltwater production, but the dynamic response, which includes hundreds of fast-flowing tidewater glaciers, is largely unknown. To develop new understanding of ice sheet dynamics, we investigated the mechanism whereby icebergs break off tidewater glaciers and form a proglacial ice melange. This melange is rigid in winter when sea ice and friction along the sidewalls of the fjord, or even at the sea floor, hold it together. The result is a resistive force, which reduces the rate of iceberg calving when the ice melange is rigid and is lost when the melange disappears in the summer. From early May to late July 2014, we launched unmanned aerial vehicles (UAVs) from a basecamp on a bluff overlooking the calving front of Store Glacier, a 5 km wide tidewater glacier flowing into Uummannaq Fjord in West Greenland. The Skywalker X8 UAVs had a wing-span of 2.1m and a payload containing a high resolution camera, an autopilot system and a GPS data logger. We generated almost 70,000 georeferenced images during 63 sorties over the glacier during a 10 week field season starting 13 May 2014. The images were used to construct orhorectified mosaics and digital elevation models of the proglacial melange with Photoscan structure-from-motion software. The imagery and the DEMs were analysed statistically to understand the spatial characteristics of the ice melange. By combining the

  20. Caracterisation des melanges developpes pour le moulage basse pression des poudres metalliques (LPIM) =

    Science.gov (United States)

    Fareh, Fouad

    Le moulage par injection basse pression des poudres metalliques est une technique de fabrication qui permet de fabriquer des pieces possedant la complexite des pieces coulees mais avec les proprietes mecaniques des pieces corroyees. Cependant, l'optimisation des etapes de deliantage et de frittage a ete jusqu'a maintenant effectuee a l'aide de melange pour lesquels la moulabilite optimale n'a pas encore ete demontree. Ainsi, la comprehension des proprietes rheologiques et de la segregation des melanges est tres limitee et cela presente le point faible du processus de LPIM. L'objectif de ce projet de recherche etait de caracteriser l'influence des liants sur le comportement rheologique des melanges en mesurant la viscosite et la segregation des melanges faible viscosite utilises dans le procede LPIM. Afin d'atteindre cet objectif, des essais rheologiques et thermogravimetriques ont ete conduits sur 12 melanges. Ces melanges ont ete prepares a base de poudre d'Inconel 718 de forme spherique (chargement solide constant a 60%) et de cires, d'agents surfactants ou epaississants. Les essais rheologiques ont ete utilises entre autre pour calculer l'indice d'injectabilite ?STV des melanges, tandis que les essais thermogravimetriques ont permis d'evaluer precisement la segregation des poudres dans les melanges. Il a ete demontre que les trois (3) melanges contenant de la cire de paraffine et de l'acide stearique presentent des indices alpha STV plus eleves qui sont avantageux pour le moulage par injection des poudres metalliques (MIM), mais segregent beaucoup trop pour que la piece fabriquee produise de bonnes caracteristiques mecaniques. A l'oppose, le melange contenant de la cire de paraffine et de l'ethylene-vinyle acetate ainsi que le melange contenant seulement de la cire de carnauba segregent peu voire pas du tout, mais possedent de tres faibles indices alphaSTV : ils sont donc difficilement injectables. Le meilleur compromis semble donc etre les melanges contenant de

  1. Supported Pd-Au Membrane Reactor for Hydrogen Production: Membrane Preparation, Characterization and Testing

    Directory of Open Access Journals (Sweden)

    Adolfo Iulianelli

    2016-05-01

    Full Text Available A supported Pd-Au (Au 7wt% membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H2, H2, N2, CO2, CH4 for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H2/N2 ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h−1, 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al2O3 catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane.

  2. Shipborne solar absorption measurements of CO2, CH4, N2O and CO and comparison with SCIAMACHY WFM-DOAS retrievals

    Directory of Open Access Journals (Sweden)

    T. Warneke

    2005-01-01

    Full Text Available CO, CH4, N2O and CO2 were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR of CH4 and CO2 are achieved using of O2 as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS retrieval algorithm show qualitatively the same latitudinal variations. WFM-DOAS data of CH4, N2O and CO2 measured over sea exhibit a great spread. The spread is significantly reduced for satellite measurements over land and a reasonable agreement can be obtained if the shipborne data are compared with the closest SCIAMACHY measurements over land. The number of comparisons is too small to draw conclusions. However, by including only WFM-DOAS data with small errors the shipborne and WFM-DOAS data compare within 5% for CH4 and CO2 and within 30% for N2O.

  3. Interactive Impacts of Nitrogen Input and Water Amendment on Growing Season Fluxes of CO2, CH4, and N2O in a Semiarid Grassland, Northern China

    Science.gov (United States)

    Zhang, L.

    2016-12-01

    Nitrogen and water are two primary limiting factors on the functioning of semiarid grasslands that play an important role on the climate system through land-atmosphere exchanges of greenhouse gases (GHG) (primarily CO2 - carbon dioxide; CH4 - methane, and N2O - nitrous oxide). However, the interactive effects of the nitrogen and water on GHG fluxes in semi-arid grasslands remain elusive. A 3-year (2010-2012) manipulative experiment in a semiarid grassland in Northern China was conducted to investigate the individual and interactive effects of nitrogen input and water amendment on GHG fluxes over growing seasons (May to September). Accumulated throughout one growing season, nitrogen input on average stimulated CO2 uptake by 3.3 ± 1.0 g C/m2/g N, enhanced N2O emission by 1.2 ± 0.3 mg N/m2/g N, and decreased CH4 uptake by 5.2 ± 0.9 mg C/m2/g N; water amendment stimulated CO2 uptake by 0.2 ± 0.1 g C/m2/mm H2O and N2O emission by 0.2 ± 0.02 mg N/m2/mm H2O, decreased CH4 uptake by 0.3 ± 0.1 mg C/m2/mm H2O. A synergistic effect between nitrogen and water additions was found on N2O flux in 2010 while the additive effects between nitrogen and water additions were found on CH4 and CO2 uptake during all experiment years, and on N2O emission in 2011 and 2012. The nitrogen addition had stronger impacts than water amendment on stimulating CH4 uptake in 2010 - the normal year, while water was the dominant factor affecting CH4 uptake in dry years. For N2O emission, the N-stimulating impact was stronger in un-watered than in watered plots, and water-stimulating impact was stronger in non-fertilized than in fertilized treatments in dry years. The mechanistic understanding of the interactive impacts of nitrogen and water additions on GHG fluxes obtained through this study provide valuable information for validating ecosystem models and understanding GHG fluxes in a multiple factors environment.

  4. Visualizing MOF Mixed Matrix Membranes at the Nanoscale : Towards Structure-Performance Relationships in CO 2 /CH 4 Separation Over NH 2 -MIL-53(Al)@PI

    NARCIS (Netherlands)

    Rodenas, T.; Van Dalen, M.; Garcia-Perez, E.; Serra-Crespo, P.; Zornoza, B.; Kapteijn, F.; Gascon, J.

    2013-01-01

    Mixed matrix membranes (MMMs) composed of metal organic framework (MOF) fi llers embedded in a polymeric matrix represent a promising alternative for CO 2 removal from natural gas and biogas. Here, MMMs based on NH 2 -MIL-53(Al) MOF and polyimide are successfully synthesized with MOF loadings up to

  5. Spatial variability and temporal dynamics of greenhouse gas (CO2, CH4, N2O) concentrations and fluxes along the Zambezi River mainstem and major tributaries

    Science.gov (United States)

    Teodoru, C. R.; Nyoni, F. C.; Borges, A. V.; Darchambeau, F.; Nyambe, I.; Bouillon, S.

    2014-11-01

    Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. As part of a~broader study on the riverine biogeochemistry in the Zambezi River basin, we present data on greenhouse gas (GHG, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHGs concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e. decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands, and the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the mainstream river were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic for the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River whereas low values were characteristic for more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to two fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced but generally higher values were found during the dry season. Overall, both concentrations and fluxes of CO2 and CH4 were well below the median/average values reported for tropical rivers, streams and reservoirs. A first-order mass balance suggests that carbon (C) transport to the ocean represents the major component (59%) of the budget (largely in the form of DIC), while only 38% of total C yield is annually emitted into the atmosphere, mostly as CO2 (98%), and 3% is removed by sedimentation in reservoirs.

  6. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget

    National Research Council Canada - National Science Library

    Teodoru, C. R; Nyoni, F. C; Borges, A. V; Darchambeau, F; Nyambe, I; Bouillon, S

    2015-01-01

    Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent...

  7. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget

    Science.gov (United States)

    Teodoru, C. R.; Nyoni, F. C.; Borges, A. V.; Darchambeau, F.; Nyambe, I.; Bouillon, S.

    2015-04-01

    Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. We present data on greenhouse gas (GHG: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes, as well as data that allow for characterization of sources and dynamics of carbon pools collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHG concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e., decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands as well as the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the main channel were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic of the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of the floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River, whereas low values were characteristic of more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to 2-fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced, but higher values were generally found during the dry season. Overall, both concentrations and fluxes of CO2 and CH4 were well below the median/average values for tropical rivers, streams and reservoirs reported previously in the literature and used for global extrapolations. A first-order mass balance suggests that carbon (C) transport to the ocean represents the major component (59%) of the budget (largely in the form of dissolved inorganic carbon, DIC), while 38% of the total C yield is annually emitted into the atmosphere, mostly as CO2 (98%), and 3% is removed by sedimentation in reservoirs.

  8. Sensitivity of the boreal forest-mire ecotone CO2, CH4, and N2O global warming potential to rainy and dry weather

    Science.gov (United States)

    Ťupek, Boris; Minkkinen, Kari; Vesala, Timo; Nikinmaa, Eero

    2015-04-01

    In a mosaic of well drained forests and poorly drained mires of boreal landscape the weather events such as drought and rainy control greenhouse gas dynamics and ecosystem global warming potential (GWP). In forest-mire ecotone especially in ecosystems where CO2 sink is nearly balanced with CO2 source, it's fairly unknown whether the net warming effect of emissions of gases with strong radiative forcing (CH4 and N2O) could offset the net cooling effect of CO2 sequestration. We compared the net ecosystem CO2 exchange (NEE) estimated from the carbon sequestrations of forest stands and forest floor CO2 fluxes against CH4 and N2O fluxes of nine forest/mire site types along the soil moisture gradient in Finland. The ground water of nine sites changed between 10 m in upland forests and 0.1 m in mires, and weather during three years ranged between exceptionally wet and dry for the local climate. The NEE of upland forests was typically a sink of CO2, regardless the weather. Though, xeric pine forest was estimated to be a source of CO2 during wet and intermediate year and became a weak sink only in dry year. The NEE of forest-mire transitions ranged between a sink in dry year, while increased stand carbon sequestration could offset the reduced forest floor CO2 emission, and a source in wet year. The NEE of two sparsely forested mires strongly differed. The lawn type mire was balanced around zero and the hummock type mire was relatively strong NEE sink, regardless the weather. Generally, nearly zero N2O emission could not offset the cooling effect of net CH4 sink and net CO2 sink of upland forest and forest-mire transitions. However in sparsely forested mires, with N2O emission also nearly zero, the CH4 emission during wet and intermediate year played important role in turning the net cooling effect of NEE into a net warming. When evaluating GWP of boreal landscapes, undisturbed forest-mire transitions should be regarded as net cooling ecosystems instead of hotspots of net warming.

  9. Post-synthetic modification of porphyrin-encapsulating metal-organic materials by cooperative addition of inorganic salts to enhance CO 2/CH 4 selectivity

    KAUST Repository

    Zhang, ZhenJie

    2012-08-21

    Keeping MOM: Reaction of biphenyl-3,4\\',5-tricarboxylate and Cd(NO 3) 2 in the presence of meso-tetra(N-methyl-4-pyridyl) porphine tetratosylate afforded porph@MOM-11, a microporous metal-organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. Porph@MOM-11 has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M +Cl -) in a stoichiometric fashion. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. CO2/CH4 Separation Performance of Ionic-Liquid-Based Epoxy-Amine Ion Gel Membranes under Mixed Feed Conditions Relevant to Biogas Processing.

    Czech Academy of Sciences Publication Activity Database

    Friess, K.; Lanč, M.; Pilnáček, Kryštof; Fíla, V.; Vopička, O.; Sedláková, Zuzana; Cowan, M.G.; McDaniel, W.M.; Noble, R.D.; Gin, D.L.; Izák, Pavel

    2017-01-01

    Roč. 528, APRIL (2017), s. 64-71 ISSN 0376-7388 R&D Projects: GA ČR GA14-12695S; GA MŠk LH14006; GA TA ČR TE01020080 Institutional support: RVO:67985858 Keywords : epoxy-amine-based ion gel membranes * biogas processing * humid mixed-gas permeation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 6.035, year: 2016

  11. Contributions to the Knowledge of Microbiological Quality of Pasteurized Melange Produced in Romania

    Directory of Open Access Journals (Sweden)

    Andreea Catalina NISTOR

    2016-11-01

    Full Text Available Today's consumers show an affinity for quality products produced under production conditions that strictly observes the principles of food safety. Bacterial contamination of eggs and egg products can thus be a source of disease for the human consumer with the necessary effects on the sector of activity. The term "egg products" defines the components of the egg (separate or as a mixture-melange released from their shell and submitted to a heat treatment, they are forming foods rich in protein, vitamins and trace elements of high quality . The purpose of this study was to establishing and monitoring the microbiological indicators of melange produced in our country. The study was carried out on the pasteurized egg mix, packaged "bag-in-box" (5 units package, and stored for a period of 25 days at the temperature recommended by the manufacturer (0 ... + 4 °C. The actual analysis is to determine NTGMA, Enterobacter spp., Bacillus spp., Pseudomonas spp., and Salmonella spp. Regarding developments of NTGMA in pasteurized melange stored for 25 days, our data showed an increase of 75.22% compared to the situation found on fresh product (3.656 log cfu/ml vs 6.406 log cfu/ml. The situation was similar for Enterobacter spp. (119.64% increase, Bacillus spp. (76.27% increase and Pseudomonas spp. (58.72% increase. Salmonella spp. was not identified in the product tested by us. The heat treatment of pasteurized liquid melange does not destroy completely the initial microbial load, therefore certain precautions are needed to store these foods.

  12. Etude des comportements rheologiques des melanges de farine ble ...

    African Journals Online (AJOL)

    Des tests de panification à base de farines composées incorporant 20 % des farines issues des différentes variétés de sorgho ont été effectués aussi au niveau de la boulangerie pilote de l'Institut de Technologie Alimentaire de Dakar. Les pains obtenus ont présenté un bon volume, une bonne texture de la mie, de la ...

  13. Studies on genesis of chromite and PGE in Naein ophiolite melange

    Directory of Open Access Journals (Sweden)

    Reza Shamsipour Dehkordi

    2011-10-01

    Full Text Available Nain ophiolite melange is located 140 Km east of Isfahan. Based on the geological studies, this area belongs to Mesozoic ophiolite of Urumieh – Dokhtar zone, west of central Iran. Country rocks are pridotite and serpentinized pridotite. The pridotite rocks are composed of Harzburgite, Lherzolite and replacement Dunite which is belong to spinel pridotite facies. Paragenesis of ore minerals are Chromite, Irarsite, Magnetite, Hematite, Pentlandite, Millerite, Chalcopyrite, Pyrite, and Covelline. Geochemical surveys of host rock and chromite show tholeiite series of magma and alpine type chromite. PGE (Ir, Pt, Pd, and Os are enriched in chromite. REE spider diagram pattern show the processes of boninitic magma and partial melting.

  14. Foliated breccias in the active Portuguese Bend landslide complex, California: bearing on melange genesis

    Energy Technology Data Exchange (ETDEWEB)

    Larue, D.K.; Hudleston, P.J.

    1987-05-01

    The active portion of the Portuguese Bend landslide complex is approximately 3 km/sup 2/ in area and 30-50 m thick. Measured displacement rates range from less than one to greater than 30 mm/day on different parts of the landslide, with total displacements over the last 30 yrs ranging from about 10 to greater than 150 m. Six types of breccia, each locally with a foliated matrix, were recognized in the active landslide complex and are absent outside the landslide complex. Slide-body breccias are of two types, the first formed by extensional fracturing during bulk pure shear at the top of the landslide (slide-top breccia) and the second by flow of tuffaceous shales and fracture of embedded siliceous shales during simple shear deep in the landslide to the basal decollement (slide-bottom breccias). Slide-margin breccias, also in simple shear, are produced on the lateral margins of individual slide blocks accompanying wrench-fault motion. Other breccias (fault-ramp breccias) are formed during motion over ramps. Colluvial deposits within tension gashes (crack-fill breccias) and at the toe of the slide (slide-toe breccias) represent a fifth breccia type. Diapirs originating from over-pressured zones at the slide base also contain breccia. Recognition of different breccia types in ancient rocks would be difficult, because fabrics in the different types are similar. Foliations are defined by: scaly cleavage, compositional banding and color banding (in shear zones), stretched mud clasts, and aligned hard grains. Foliated breccias are synonymous with melanges. The authors regard the six breccia types described herein as representing the principal types of melange that occur in ancient accretionary settings.

  15. Une alternative au cobalt pour la synthese de nanotubes de carbone monoparoi par plasma inductif thermique

    Science.gov (United States)

    Carrier, Jean-Francois

    Les nanotubes de carbone de type monoparoi (C-SWNT) sont une classe recente de nanomateriaux qui ont fait leur apparition en 1991. L'interet qu'on leur accorde provient des nombreuses proprietes d'avant-plan qu'ils possedent. Leur resistance mecanique serait des plus rigide, tout comme ils peuvent conduire l'electricite et la chaleur d'une maniere inegalee. Non moins, les C-SWNT promettent de devenir une nouvelle classe de plateforme moleculaire, en servant de site d'attache pour des groupements reactifs. Les promesses de ce type particulier de nanomateriau sont nombreuses, la question aujourd'hui est de comment les realiser. La technologie de synthese par plasma inductif thermique se situe avantageusement pour la qualite de ses produits, sa productivite et les faibles couts d'operation. Par contre, des recherches recentes ont permis de mettre en lumiere des risques d'expositions reliees a l'utilisation du cobalt, comme catalyseur de synthese; son elimination ou bien son remplacement est devenu une preoccupation importante. Quatre recettes alternatives ont ete mises a l'essai afin de trouver une alternative plus securitaire a la recette de base; un melange catalytique ternaire, compose de nickel, de cobalt et d'oxyde d'yttrium. La premiere consiste essentiellement a remplacer la proportion massique de cobalt par du nickel, qui etait deja present dans la recette de base. Les trois options suivantes contiennent de nouveaux catalyseurs, en remplacement au Co, qui sont apparus dans plusieurs recherches scientifiques au courant des dernieres annees: le dioxyde de zircone (ZrO2), dioxyde de manganese (MnO2) et le molybdene (Mo). La methode utilisee consiste a vaporiser la matiere premiere, sous forme solide, dans un reacteur plasma a haute frequence (3 MHz) a paroi refroidi. Apres le passage dans le plasma, le systeme traverse une section dite de "croissance", isolee thermiquement a l'aide de graphite, afin de maintenir une certaine plage de temperature favorable a la

  16. Study of total ionization by {alpha} particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature; Etude de l'ionisation totale par les paricules {alpha}, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-07-01

    effet de temperature sur W, dans les melanges gazeux binaires du type A - B contenant des atomes metastables A{sup *} et une 'impurete' B. On etudie systematiquement la variation {delta}W de W en fonction de la temperature et de la concentration de 'l'impurete' B dans les melanges Ne - Ar, Ne - Kr, Ne - H{sub 2}, Ne - N{sub 2}, Ne - CH{sub 4} et He - Ar. On realise des experiences sur un melange gazeux ternaire du type A - B - C, ou C est une deuxieme 'impurete' ionisable que l'on ajoute au melange binaire A - B, demontrant l'existence d'atomes excites B{sup *} de 'l'impurete' B. Enfin, on montre que la quantite d'atomes metastables formes dans un gaz pur, doit etre tres proche du nombre N{sub 0} de paires d'ions et qu'il doit y avoir correlation entre lenombre N{sub 0} de paires d'ions et le nombre {approx_equal} N{sub 0} d'atomes metastables crees dans les gaz rares purs. (auteur)

  17. Relationships between the potential production of the greenhouse gases CO2, CH4 and N2O and soil concentrations of C, N and P across 26 paddy fields in southeastern China

    Science.gov (United States)

    Wang, Weiqi; Sardans, Jordi; Wang, Chun; Zeng, Congsheng; Tong, Chuan; Asensio, Dolores; Peñuelas, Josep

    2017-09-01

    Paddy fields are a major global anthropogenic source of greenhouse gases. China has the second largest area under rice cultivation, so determining the relationships between the emission of greenhouse gases and soil carbon content, nutrient availabilities and concentrations and physical properties is crucial for minimizing the climatic impacts of rice agriculture. We examined soil nutrients and other properties, greenhouse-gas production and their relationships in 26 paddy fields throughout the province of Fujian in China, one of the most important provinces for rice production. High P and K concentrations, contents and availabilities were correlated with low rates of CO2 production, whereas high C and N contents were correlated with high rates of CH4 production. Mean annual precipitation (MAP) and rates of gas production were not clearly correlated, at least partly due to the management of flooding that can mask the effect of precipitation. Higher mean annual temperatures and soil Fe contents favored the production of N2O. C, N, P and K concentrations and their ratios, especially the C:K and N:K ratios, and P availability were correlated with CO2 and CH4 production across the province, with higher C:K and N:K ratios correlated positively with increased CO2 production and available P correlated negatively with CH4 production. A management strategy to avoid excessive C accumulation in the soil and to increase P availability and decrease available Fe contents would likely decrease the production of greenhouse gases.

  18. Design of Pore Size and Functionality in Pillar-Layered Zn-Triazolate-Dicarboxylate Frameworks and Their High CO2/CH4 and C2 Hydrocarbons/CH4 Selectivity.

    Science.gov (United States)

    Zhai, Quan-Guo; Bai, Ni; Li, Shu'ni; Bu, Xianhui; Feng, Pingyun

    2015-10-19

    In the design of new materials, those with rare and exceptional compositional and structural features are often highly valued and sought after. On the other hand, materials with common and more accessible modes can often provide richer and unsurpassed compositional and structural variety that makes them a more suitable platform for systematically probing the composition-structure-property correlation. We focus here on one such class of materials, pillar-layered metal-organic frameworks (MOFs), because different pore size and shape as well as functionality can be controlled and adjusted by using pillars with different geometrical and chemical features. Our approach takes advantage of the readily accessible layered Zn-1,2,4-triazolate motif and diverse dicarboxylate ligands with variable length and functional groups, to prepare seven Zn-triazolate-dicarboxylate pillar-layered MOFs. Six different gases (N2, H2, CO2, C2H2, C2H4, and CH4) were used to systematically examine the dependency of gas sorption properties on chemical and geometrical properties of those MOFs as well as their potential applications in gas storage and separation. All of these pillar-layered MOFs show not only remarkable CO2 uptake capacity, but also high CO2 over CH4 and C2 hydrocarbons over CH4 selectivity. An interesting observation is that the BDC ligand (BDC = benzenedicarboxylate) led to a material with the CO2 uptake outperforming all other metal-triazolate-dicarboxylate MOFs, even though most of them are decorated with amino groups, generally believed to be a key factor for high CO2 uptake. Overall, the data show that the exploration of the synergistic effect resulting from combined tuning of functional groups and pore size may be a promising strategy to develop materials with the optimum integration of geometrical and chemical factors for the highest possible gas adsorption capacity and separation performance.

  19. Inter-seasonal and spatial distribution of ground-level greenhouse gases (CO2, CH4, N2O) over Nagpur in India and their management roadmap.

    Science.gov (United States)

    Majumdar, Deepanjan; Rao, Padma; Maske, Nilam

    2017-03-01

    Ground-level concentrations of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) were monitored over three seasons, i.e., post-monsoon (September-October), winter (January-February), and summer (May-June) for 1 year during 2013-2014 in Nagpur City in India. The selected gases had moderate to high variation both spatially (residential, commercial, traffic intersections, residential cum commercial sites) and temporally (at 7:00, 13:00, 18:00, and 23:00 hours in all three seasons). Concentrations of gases were randomly distributed diurnally over city in all seasons, and there was no specific increasing or decreasing trend with time in a day. Average CO 2 and N 2 O concentrations in winter were higher over post-monsoon and summer while CH 4 had highest average concentration in summer. Observed concentrations of CO 2 were predominantly above global average of 400 ppmv while N 2 O and CH 4 concentrations frequently dropped down below global average of 327 ppbv and 1.8 ppmv, respectively. Two-tailed Student's t test indicated that post-monsoon CO 2 concentrations were statistically different from summer but not so from winter, while difference between summer and winter concentrations was statistically significant (P gases calculated for three seasons together were higher in commercial areas. Environmental management priorities vis a vis greenhouse gas emissions in the city are also discussed.

  20. Two-year record of trace gas (CO2, CH4, O2, and Hg0) concentrations and dynamics in arctic tundra soils of northern Alaska - seasonality, non-linear temperature controls, and effects of soil diffusivity

    Science.gov (United States)

    Obrist, D.; Agnan, Y.; Hedge, C.; Moore, C. W.; Helmig, D.; Hueber, J.; Paxton, D.

    2016-12-01

    The goal of this study was to assess the seasonality and temperature sensitivity of tundra soil trace gas evolution. Two years of in situ measurements of carbon dioxide (CO2), methane (CH4), oxygen (O2), and gaseous mercury (Hg0) concentrations were conducted in soils at Toolik Field station using six trace gas wells deployed across two soil profiles and different depths. Soil trace gases were sampled at regular intervals through heated tubing with gas analyzers housed in a field laboratory. Additional measurements included soil temperature and moisture profiles, trace gases in overlying snowpack, and whole-ecosystem trace gas exchange using micrometeorological methods. We show that soil CO2 concentrations exceeded concentrations in the atmosphere year-round, indicative of a consistent soil CO2 source that lasted throughout the arctic winter. Correlations between CO2 concentrations and soil temperatures were weak, and some of the highest soil CO2 concentrations, along with low O2 levels, were observed in December and January. We attribute these unexpected patterns to a strong control of soil diffusivity on trace gas concentrations as soil freezing and the development of the snowpack dramatically reduced gas diffusion rates from soils to the atmosphere. The two soil profiles within close proximity (pollutant, showed that tundra soils were consistent atmospheric Hg0 sinks. Along with corresponding ecosystem-level flux measurements showing pronounced net atmospheric Hg0 deposition, we determine that dry deposition of mercury to arctic ecosystems was the main source for soil accumulation. In conclusion, these results indicate a highly heterogeneous pattern of soil trace gas dynamics in tundra soils, with strong changes in diffusivity imposed by freeze-thaw cycles and strong and non-linear responses of trace gas dynamics to soil temperatures.

  1. Middle Jurassic Radiolaria from a siliceous argillite block in a structural melange zone near Viqueque, Timor Leste: Paleogeographic implications

    Science.gov (United States)

    Haig, David W.; Bandini, Alexandre Nicolas

    2013-10-01

    Thin-bedded siliceous argillite forming a large block within a structural melange zone at Viqueque, Timor Leste, has yielded a Middle Jurassic (late Bathonian-early Callovian) radiolarian assemblage belonging to Unitary Association Zone 7. Fifty-five species are recognized and illustrated, forming the most diverse radiolarian fauna yet documented from the Jurassic of Timor. The fauna shows little similarity in species content to the few other assemblages previously listed from the Middle or Late Jurassic of Timor, and also has few species in common with faunas known elsewhere in the region from Rotti, Sumatra, South Kalimantan, and Sula. Based on lithofacies similarities and age, the siliceous argillite succession in the melange block at Viqueque is included in the Noni Group originally described as the lower part of the Palelo Series in West Timor. In terms of lithofacies, the Noni Group is distinct from other stratigraphic units known in Timor. It may be associated with volcanic rocks but age relationships are uncertain, although some of the radiolarian cherts in the Noni Group in West Timor have been reported to include tuffaceous sediment. The deep-water character of the siliceous hemipelagite-pelagite facies, the probable volcanic association, and an age close to that of continental breakup in the region suggest deposition in a newly rifted Indian Ocean. In Timor's tectonostratigraphic classification scheme, the Noni Group is here placed in the "Indian Ocean Megasequence".

  2. Numerical model of ice melange expansion during abrupt ice-shelf collapse

    Science.gov (United States)

    Guttenberg, N.; Abbot, D. S.; Amundson, J. M.; Burton, J. C.; Cathles, L. M.; Macayeal, D. R.; Zhang, W.

    2010-12-01

    evolve into full-blown collapse of the ice shelf? What proportion of uncapsizable icebergs prevent a collapse?), (b) the rates of mobilization and their dependence on iceberg geometry (e.g., what determines the speed at which the expanding ice melange moves into the open, ice-free water?), and (c) the factors that promote the arrest of the system (e.g., are there circumstances where only partial collapses can occur?). Results of simulations are compared with observational parameters derived from satellite imagery, seismic analysis and laboratory experiment to determine what aspects of the numerical model's physical formulation may have most relevance to the disappearance of ice shelves.

  3. Bulk rheology and simulated episodic tremor and slip within a numerically-modeled block-dominated subduction melange

    Science.gov (United States)

    Webber, S.; Ellis, S. M.; Fagereng, A.

    2015-12-01

    We investigate the influence of melange rheology in a subduction thrust interface on stress and slip cycling constrained by observations from an exhumed subduction complex at Chrystalls Beach, New Zealand. A two-phase mélange dominated by large, competent brittle-viscous blocks surrounded by a weak non-linear viscous matrix is numerically modeled, and the evolution of bulk stress are analysed as the domain deforms. The models produce stress cycling behaviour under constant shear strain rate boundary conditions for a wide range of physical conditions that roughly corresponds to depths and strain rates calculated for instrumentally observed episodic tremor and slip (ETS) in presently-deforming subduction thrust interfaces. Stress cycling is accompanied by mixed brittle plastic-viscous deformation, and occurs as a consequence of geometric reorganisation and the progressive development and breakdown of stress bridges as blocks mutually obstruct one another. We argue that periods of low differential stress correspond to periods of rapid mixed-mode deformation and ETS. Stress cycling episodicities are a function of shear strain rate and pressure/temperature conditions at depth. The time period of stress cycling is principally controlled by the geometry (block distribution and density through time) and stress cycling amplitudes are controlled by effective stress. The duration of stress cycling events in the models (months-years) and rapid strain rates are comparable to instrumentally observed ETS. Shear strain rates are 1 - 2 orders of magnitude slower between stress cycling events, suggesting episodic return times within a single model domain are long duration (> centennial timescales), assuming constant flow stress. Finally, we derive a bulk viscous flow law for block dominated subduction mélanges for conditions 300 - 500°C and elevated pore fluid pressures. Bulk flow laws calculated for block-dominated subduction mélanges are non-linear, owing to a combination of

  4. L'Apprentissage de la Langue de l'Expose Litteraire au Laboratoire (The Learning of the Language of the Literary Essay in the Laboratory). Melanges Pedagogiques, 1970.

    Science.gov (United States)

    Jochum, C.

    This article describes an attempt to give university students of English as a second language instruction in writing literary essays. The students were given literary commentaries to listen to in the language laboratory, and then were asked to summarize these commentaries, using, as much as possible, the structures contained in the original…

  5. L'Apprentissage des Langues au Niveau Debutant: Le Probleme des Supports Ecrits (Second Language Learning at the Elementary Level: The Problem of Writing). Melanges Pedagogiques, 1976

    Science.gov (United States)

    Cembalo, M.; And Others

    The experiment reported on in this article is an attempt to cope satisfactorily with the problem of introducing writing in an elementary second language course. In the beginners' course set up at the C.R.A.P.E.L., the decision was made not to "introduce" the written language but to enable the learners, from the beginning of the course, to write…

  6. High-Pressure/Low-Temperature Melanges in the Cycladic Blueschist Belt, Greece: Results of an Ionprobe (SHRIMP) U-Pb Study

    Science.gov (United States)

    Bröcker, M.; Keasling, A.; Pidgeon, R. T.

    2005-12-01

    The Cycladic blueschist belt (CBB) in the central Aegean Sea has experienced epidote blueschist to eclogite facies metamorphism in the Eocene (c. 50-40 Ma) during collisional processes between the Apulian microplate and Eurasia. The general geological framework is well established, but many details of the tectonometamorphic history still are not fully understood. Unresolved issues concern the importance of pre-Eocene HP metamorphism [1, 2] and the geochronological record that is preserved in melange sequences. These aspects are addressed in an ionprobe (SHRIMP) U-Pb zircon study focusing on block-matrix associations from the islands of Syros and Andros. Melanges comprise in variable mixtures eclogites, glaucophanites, meta-gabbros, ultrabasic rocks, meta-acidic gneisses and jadeitites in a serpentinitic and/or metasedimentary matrix. The origin of the block-matrix associations is controversial and in many cases it remains unclear whether these melanges record sedimentary or tectonic processes. A tectonic slab from Syros, consisting of an interlayered meta-acidic gneiss - glaucophanite sequence, yielded 206Pb/238U ages of c. 237-245 Ma, similar to ages determined for rocks collected from structurally coherent sequences on other Cycladic islands. On Syros, we have also studied zircons from a metasomatic alteration profile, which developed around a compound eclogite-jadeitite net-veined block enclosed in a serpentinite matrix. From the outside in, distinct blackwall alteration zones (c. 5-30 cm in thickness) can be distinguished, which predominantly consist either of actinolite- chlorite, glaucophane or omphacite. Zircon from the unaltered jadeitite and all reaction zones yielded 206Pb/238U ages of c. 80 Ma. Across this profile, systematic changes are observed in zircon morphology and CL patterns. U- and Th-concentrations in zircon decrease towards the peripheral rinds. These observations are difficult to reconcile with a magmatic origin of the zircons and instead we

  7. Strongly foliated garnetiferous amphibolite clasts in ophiolitic melanges, Yarlung Zangbo Suture Zone, Tibet; Early Cretaceous disruption of a back-arc basin?

    Science.gov (United States)

    Guilmette, C.; Hebert, R.; Wang, C.; Indares, A. D.; Ullrich, T. D.; Dostal, J.; Bedard, E.

    2007-12-01

    Metre to decameter-size clasts of amphibolite are found embedded in ophiolitic melanges underlying the Yarlung Zangbo Suture Zone Ophiolites, South Tibet, China. These ophiolites and melanges occur at the limit between Indian and Tibetan-derived rocks and represent remnants of an Early Cretaceous intraoceanic supra-subduction zone domain, the Neo-Tethys. In the Saga-Dazuka segment (500 km along-strike), we discovered new occurrences of strongly foliated amphibolites found as clasts in the ophiolitic melange. In garnet-free samples, hornblende is green-blue magnesio-hornblende and cpx is low-Al diopside. In garnet- bearing samples, garnet is almandine with a strong pyrope component (up to 30 mol%) whereas coexisting hornblende is brown Ti-rich tschermakite and clinopyroxene is Al-diopside. Plagioclase composition was ubiquitously shifted to albite during a late metasomatic event. Geochemistry of these rocks indicates that their igneous protoliths crystallized from a slightly differentiated tholeiitic basaltic liquid that did not undergo major fractionation. Trace element patterns reveal geochemical characteristics identical to those of the overlying ophiolitic crust. These are 1) trace element abundances similar to that of N-MORBs or BABBs, 2) a slight depletion of LREE and 3) a moderate to strong Ta-Nb negative anomaly and a slight Ti anomaly. Such characteristics suggest genesis over a spreading center close to a subduction zone, possibly a back-arc basin. Step-heating Ar/Ar plateau ages were obtained from hornblende separates. All ages fall in the range of 123-128 Ma, overlapping the crystallization ages from the overlying ophiolite (126-131 Ma). Pseudosections were built with the THERMOCALC software in the system NCFMASH. Results indicate that the observed assemblage Hb+Pl+Gt+Cpx is stable over a wide range of P-T conditions, between 10-18 kbars and at more than 800°C. Measured mineral modes and solid solution compositions were successfully modeled, indicating

  8. Study of acid-base properties in various water-salt and water-organic solvent mixtures; Etude de proprietes acides-bases dans divers melanges eau-sels et eau-solvants organiques

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-02-01

    Acid-base reactions have been studied in water-salt mixtures and water organic solvent-mixtures. It has been possible to find some relations between the displacement of the equilibria and the numerical value of water activity in the mixture. First have been studied some equilibria H{sup +} + B {r_reversible} HB{sup +} in salt-water mixtures and found a relation between the pK{sub A} value, the solubility of the base and water activity. The reaction HO{sup -} + H{sup +} {r_reversible} H{sub 2}O has been investigated and a relation been found between pK{sub i} values, water activity and the molar concentration of the salt in the mixture. This relation is the same for every mixture. Then the same reactions have been studied in organic solvent-water mixtures and a relation found in the first part of the work have been used with success. So it has been possible to explain easily some properties of organic water-mixture as the shape of the curves of the Hammett acidity function Ho. (authors) [French] Nous avons envisage l'etude des reactions acides-bases dans des melanges eau-sels MX et des melanges d'eau et de solvants organiques. Les uns et les autres ont ete choisis de facon a ce que la basicite du solvant ou celle de l'anion X{sup -} soit negligeable devant celle de l'eau dans les melanges consideres. Dans un premier temps nous avons etudie dans les melanges eau-sels MX les equilibres H{sup +} + B {r_reversible} HB{sup +} et HA {r_reversible} H{sup +} + A{sup -}. On montre que connaissant la valeur de la solubilite de la base B et de l'acide HA dans le melange eau-sel considere et dans l'eau pure et celle de l'activite de l'eau dans le melange, il est possible de prevoir la valeur de la constante de l'equilibre acide-base etudiee. Dans un deuxieme temps nous avons cherche a generaliser ces resultats, lorsque l'on remplace le sel MX dans le melange avec l'eau par un solvant organique. De meme que precedemment

  9. AU BURKINA FASO

    African Journals Online (AJOL)

    Les moyennes sur la même ligne et possédant le même indice ne diffèrent pas significativement au seuil de 5 %. ME : mélange fourrager. 10-20-30 % : pourcentage de concentré. GMQ : Gain Moyen Quotidien. L'analyse des résultats des rations. 1 et 2 montre que l'accès au pâturage permet des performances supérieures.

  10. Contribution to the study of thermal diffusion in isotopic mixtures of hydrogen; Contribution a l'etude de la diffusion thermique dans les melanges isotopiques de l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Lemarechal-Dupuis, A. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-04-01

    Thermal diffusion constants of the mixtures H{sub 2}-HD and H{sub 2}-HT, where HD and HT were at trace concentrations, have been measured between 90 deg. K and 450 deg. K for H{sub 2}-HD and between 190 deg. K and 450 deg. K for H{sub 2}-HT, by using the elementary effect. Furthermore, the ratio of these constants has been measured by using a thermo-gravitational column of Clusius and Dickel, at temperatures of the hot wire between 455 deg. K and 1200 deg. K, the cold wall being at room temperature. Comparison with the predictions of existing theories shows that the Chapman-Enskog theory cannot account for the thermal diffusion of mixtures containing asymmetric molecules; the possible reasons for this disagreement are discussed. Our set of measurements, combined with the results of other authors, yields precise values at well defined conditions of temperature and concentration, useful for the determination of the coefficients of the semi-empirical expansion of Waldmann and Klemm. Furthermore some aspects of the column theory according to Furry and Jones have been tested. (author) [French] Les constantes de diffusion thermique des melanges H{sub 2}-HD et H{sub 2}-HT ou HD et HT figuraient, a l'etat de traces, ont ete mesurees a l'aide de l'effet elementaire entre 90 deg. K et 450 deg. K pour le melange H{sub 2}-HD,et entre 190 deg. K et 450 deg. K pour le melange H{sub 2}-HT. D'autre part, le rapport de ces constantes a ete mesure a l'aide d'une colonne de Clusius et Dickel pour des temperatures du fil chaud variant entre 455 deg. K et 1200 deg. K, la temperature de la paroi froide etant la temperature ambiante. La comparaison avec les predictions des theories existantes montre que la theorie de Chapman- Enskog ne peut rendre compte de la constante de diffusion thermique de melanges de molecules asymetriques; les raisons de ce desaccord sont discutees. L'ensemble de ces mesures, combine aux resultats d'autres auteurs, permet d

  11. Au pair trajectories

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send...

  12. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  13. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NARCIS (Netherlands)

    Popa, Maria Elena|info:eu-repo/dai/nl/375806407; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.|info:eu-repo/dai/nl/330541242; Rothe, M.; Röckmann, T.|info:eu-repo/dai/nl/304838233

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in

  14. Low energy {beta} counts at the radioactivity measurement laboratory of Grenoble; Les comptages {beta} de faibles energies effectues au L.M.R Grenoble

    Energy Technology Data Exchange (ETDEWEB)

    Duplaa, AM.; Chevalier, M.; Choudens, H. de [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1966-07-01

    Radioelements emitting {beta} low energy are very useful in biology specially in labelled compounds. The counting method with liquid scintillator is very often used. The radioactivity measurement laboratory of Grenoble uses for these measures a Tricarb-Packard. The samples to be counted are: tritiated water which is measured with a dioxane scintillator; animals textures which is measured with a dioxane scintillator; animals textures which contain {sup 14}C: these samples are dissolved in hyamine 10 X, then melted with a toluene scintillator, solid samples containing {sup 14}C or {sup 45}Ca (plant ashes); these samples are measured by suspension in scintillating mixtures. Gaseous samples {sup 14}CO{sub 2} are also counted, the gas is retained by hyamine, then mixed with a liquid scintillator. Counting of double labelled samples are also made {sup 4}5{sup C}a + {sup 32}P and {sup 14}C + {sup 32}P. The quenching corrections are made by internal standardization method, by channels ratio method or better by external standardization method. (author) [French] Les emetteurs {beta} de faible energie (C{sup 14}, H{sup 3}, Ca{sup 45}) sont tres utilises en biologie sous forme de molecules marquees. La methode de comptage par scintillateur liquide est celle qui est la plus employee. Le LMR de Grenoble effectue la mesure de ces emetteurs avec un appareil Tricarb-Packard. Les comptages portent sur des ehantillons d'eau titree comptee avec un scintillateur au dioxane; des echantillons de tissus animaux contenant du C{sup 14} sont dissous par de l'hyamine puis melange a un scintillateur au toluene. Des echantillons solides (cendres de vegetaux) contenant du C{sup 14} ou du Ca{sup 45} sont comptes sous forme de gels scintillants; des echantillons gazeux de {sup 14}CO{sub 2}, le gaz est retenu par de l'hyamine puis melange au scintillateur liquide. Enfin des comptages d'echantillons doublement marques CO{sup 45} + P{sup 32} et C{sup 14} + P{sup 32} sont effectues

  15. Mise au point

    African Journals Online (AJOL)

    31 mai 2013 ... laryngocèle interne. Une surinfection a été notée chez trois patients réalisant ainsi le tableau de pyolaryngocèle. Tous les patients ont eu un examen clinique complet comportant un examen OrL et cervico-facial ainsi qu'un examen laryngé au ... pas en communication avec la lumière laryngée. La taille.

  16. Le CRDI au Mali

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

    sur la sécurité alimentaire internationale. Le CRDI continue de soutenir des travaux de recherche au Mali, quoique dans une moindre mesure en raison de la .... souvent tenues à l'écart du processus décisionnel. Les chercheurs tentent de déterminer de quelles manières les jeunes femmes du Mali et des pays avoisinants ...

  17. Mise au point

    African Journals Online (AJOL)

    7 mai 2012 ... Le carcinome folliculaire est la deuxième tumeur maligne la plus fréquente de la thyroïde et l'invasion hématologique est le moyen de propagation le plus courant de ses métastases. Les localisations secondaires à ces cancers siègent principalement au niveau des poumons, suivi par les localisations.

  18. Le CRDI au Maroc

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

    visant à aider les secteurs de l'agriculture et du tourisme à s'adapter aux changements climatiques. Dans le cadre de recherches antérieures sur la mise au point .... France. Les manifestations et protestations survenues après 2010 et auxquelles on a donné le nom de Printemps arabe ont été annonciatrices de profondes ...

  19. Mise au point

    African Journals Online (AJOL)

    7 mai 2012 ... EPIdEMIOlOgIE ET ETIOPAThOgENIE. Les angiodysplasies osseuses des maxillaires sont rares. Les premiers cas rapportés sont ceux de Berard qui a décrit en 1842 une localisation au niveau du maxillaire supérieur et de Stanley qui a rapporté en 1849 une loca- lisation mandibulaire. une prédisposition ...

  20. Le CRDI au Kenya

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

    et de l'agriculture. En produisant des connaissances dans ces secteurs essentiels, le programme contribuera à la sécurité alimentaire et améliorera la santé au Kenya. Les noms et les frontières indiqués sur la carte n'impliquent ni reconnaissance ni acceptation officielle de la part du CRDI. C. U. R. T. C. A. R. N. EM. A. R. K.

  1. Mise au point

    African Journals Online (AJOL)

    31 mai 2013 ... L'attitude théra- peutique dépend du type de la laryngocèle. en effet, le traitement endoscopique au laser CO2 a gagné beaucoup d'intérêt ces dernières années. MATÉRIEL ET MÉTHOdES. Il s'agit d'une étude rétrospective portant sur 9 patients porteurs d'une laryngocèle colligés sur une période de 14.

  2. Le CRDI au Ghana

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

    poussée en mathématiques aux spécialistes de demain afin qu'ils puissent relever les défis pressants qui se posent en matière d'environnement, de santé et d'économie. La bourse de chercheur invité que le CRDI a octroyée en 2001 au regretté. John Atta-Mills, qui a par la suite été prési- dent du Ghana de 2009 à 2012, ...

  3. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Ethnographers are increasingly making use of Facebook to acquire access and general acquaintance with their field of study. However, little has been written on how Facebook is used methodologically in research that does not have social media sites as the main focus of interest. This article argues...... that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...... and on Facebook....

  4. Mise au point

    African Journals Online (AJOL)

    7 mai 2012 ... acquis et des anomalies génétiques associées ont été aussi incriminés (mutation du gène Fas ou de la p53, délétion au niveau du chromosome 6q, méthylation excessive de la p73) (15,16). Le mode de révélation de ces lymphomes est peu spéci- fique et parfois banal. L'obstruction nasale représente le.

  5. Charged particle density distributions in Au+ Au collisions at ...

    Indian Academy of Sciences (India)

    ... measured in Au + Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions of different parton scattering models and the important role of hard scattering processes at RHIC energies is discussed ...

  6. Magnetoresistance of Au films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D. L., E-mail: zhangdl@iphy.ac.cn; Song, X. H.; Zhang, X. [Institute of Physics, Chinese Academy of Sciences, Beijing 10081 (China); Zhang, X.-G., E-mail: xgz@ufl.edu [Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611 (United States); Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6493 (United States)

    2014-12-14

    Classical magnetoresistance (MR) in nonmagnetic metals are conventionally understood in terms of the Kohler rule, with violation usually viewed as anomalous electron transport, in particular, as evidence of non-Fermi liquid behavior. Measurement of the MR of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms. Consequently, the Kohler rule should not be used to distinguish normal and anomalous electron transport in solids.

  7. Multifragmentation in Au + Au collisions studied with AMD-V

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Akira [Tohoku Univ., Sendai (Japan). Faculty of Science

    1998-07-01

    AMD-V is an optimum model for calculation of multifragmentation in Au + Au collisions. AMD-V consider anti-symmetry of incident nucleus, target nucleus and fragments, furthermore, it treat the quantum effect to exist many channels in the intermediate and final state. 150 and 250 MeV/nucleon incident energy were used in the experiments. The data of multifragment atom in {sup 197}Au + {sup 197}Au collisions was reproduced by AMD-V calculation using Gognny force, corresponding to the imcompressibility of nuclear substance K = 228 MeV and its mean field depend on momentum. When other interaction (SKG 2 force, corresponding to K = 373 KeV) was used an mean field does not depend on momentum, the calculation results could not reproduce the experimental values, because nucleus and deuteron were estimated too large and {alpha}-particle and intermediate fragments estimated too small. (S.Y.)

  8. Face au risque

    CERN Document Server

    Grosse, Christian; November, Valérie

    2007-01-01

    Ce volume collectif sur le risque inaugure la collection L'ÉQUINOXE. Ancré dans l'histoire pour mesurer les continuités et les ruptures, il illustre la manière dont les sciences humaines évaluent et mesurent les enjeux collectifs du risque sur les plans politiques, scientifiques, énergétiques, juridiques et éthiques. Puisse-t-il nourrir la réflexion sur la culture et la prévention du risque. Ses formes épidémiques, écologiques, sociales, terroristes et militaires nourrissent les peurs actuelles, structurent les projets sécuritaires et constituent - sans doute - les défis majeurs à notre modernité. Dans la foulée de la richesse scientifique d'Equinoxe, L'ÉQUINOXE hérite de son esprit en prenant à son tour le pari de contribuer - non sans risque - à enrichir en Suisse romande et ailleurs le champ éditorial des sciences humaines dont notre société a besoin pour forger ses repères. Après Face au risque suivra cet automne Du sens des Lumières. (MICHEL PORRET Professeur Ordinaire à la F...

  9. Chiral magnetic effect search in p+Au, d+Au and Au+Au collisions at RHIC

    Science.gov (United States)

    Zhao, Jie; STAR Collaboration

    2017-09-01

    The chiral magnetic effect (CME) is a fundamental property of QCD. A major background source for CME measurements is the intrinsic particle correlations (such as resonances/jets decay) coupled with the azimuthal elliptical anisotropy v2. In heavy-ion collisions, the magnetic field direction and event plane azimuthal angle Ψ2 are correlated, thus the CME and the v2-induced background are entangled. In small system p+Au and d+Au collisions, the Ψ2 is mostly due to geometry fluctuations, and thus magnetic field direction and Ψ2 are uncorrelated. The correlation measurements in small system collisions with respect to Ψ2 are only sensitive to v2-induced background while any CME is averaged to zero. In this talk, we will present the STAR measurements of two-particle correlations with respect to Ψ2 in p+Au, d+Au and Au+Au collisions at √{sNN} = 200 GeV. These results are analyzed as a function of particle multiplicity to shed light on the background contaminations of the CME measurements in heavy-ion collisions. We will also report results from a new analysis approach as a function of the particle pair invariant mass in order to suppress non-CME related physics backgrounds.

  10. Borophene synthesis on Au(111)

    Science.gov (United States)

    Guisinger, Nathan; Kiraly, Brian; Zhang, Zhuhua; Mannix, Andrew; Hersam, Mark C.; Yakobson, Boris I.

    The recent experimental discovery of borophene, the metallic 2-dimensional allotrope of boron, has sparked tremendous interest in further exploration of this unique material. The initial synthesis of borophene was accomplished on Ag substrates and serves as a quintessential example of predictive modeling to experimental realization. In this talk, we expand the phase-space of borophene synthesis to Au. Borophene synthesis was accomplished by evaporating elemental boron onto a Au(111) substrate. The synthesized borophene retains its metallic character on Au as verified with scanning tunneling spectroscopy. Most fascinating is the difference in growth dynamics on the Au(111) substrate where the reconstructed surface presents a unique energy landscape for borophene nucleation and growth. We find that the initial low-coverage growth of borophene modifies the herringbone reconstruction into a ``trigonal'' network, where the 2D boron islands are uniformly templated across the surface. Increasing coverage results in the increasing size of the templated borophene islands until they coalesce into larger sheets. The observed growth dynamics are supported by the computational modeling of boron nucleation on Au.

  11. L’apprentissage au cern

    CERN Multimedia

    2007-01-01

    pour les professions d’électronicien(ne) et de laborantin(e) en physique L’apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le canton de Genève. En cas de réussite à l’examen de fin d’apprentissage, les apprentis obtiennent le Certificat fédéral de capacité suisse (CFC). 6 places au total sont ouvertes au recrutement pour les deux professions. L’apprentissage dure 4 ans. Minima requis pour faire acte de candidature : avoir au moins 15 ans et moins de 21 ans à la date de début de l’apprentissage ; avoir terminé la scolarité obligatoire, au minimum 9e du Cycle d’orientation genevois (3e en France) ; être ressortissant d’un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne, Finlande, France, Grèce, Hongrie, Italie, Norvège, Pays-Bas, Pologne, Portugal, Royaume-Uni, République tchèque, République slovaque , Suède, Suisse) ; pour les résidents en Suisse : être ressortissant su...

  12. Transverse Velocity Scaling in Au+Au Fragmentation

    OpenAIRE

    Lukasik, J.; Hudan, S.; Lavaud, F.; Turzo, K.; Auger, G.; Bacri, Ch.O.; Begemann-Blaich, M.L.; Bellaize, N.; Bittiger, R.; Bocage, F.; Borderie, B.; Buchet, P.; R. Bougault(LPCC); Bouriquet, B.; Charvet, J. L.

    2002-01-01

    Invariant transverse-velocity spectra of intermediate-mass fragments were measured with the 4-pi multi-detector system INDRA for collisions of Au on Au at incident energies between 40 and 150 MeV per nucleon. Their scaling properties as a function of incident energy and atomic number Z are used to distinguish and characterize the emissions in (i) peripheral collisions at the projectile and target rapidities, and in (ii) central and (iii) peripheral collisions near mid-rapidity. The importance...

  13. Multiscale Modeling of Au-Island Ripening on Au(100

    Directory of Open Access Journals (Sweden)

    Karin Kleiner

    2011-01-01

    Full Text Available We describe a multiscale modeling hierarchy for the particular case of Au-island ripening on Au(100. Starting at the microscopic scale, density functional theory was used to investigate a limited number of self-diffusion processes on perfect and imperfect Au(100 surfaces. The obtained structural and energetic information served as basis for optimizing a reactive forcefield (here ReaxFF, which afterwards was used to address the mesoscopic scale. Reactive force field simulations were performed to investigate more diffusion possibilities at a lower computational cost but with similar accuracy. Finally, we reached the macroscale by means of kinetic Monte Carlo (kMC simulations. The reaction rates for the reaction process database used in the kMC simulations were generated using the reactive force field. Using this strategy, we simulated nucleation, aggregation, and fluctuation processes for monoatomic high islands on Au(100 and modeled their equilibrium shape structures. Finally, by calculating the step line tension at different temperatures, we were able to make a direct comparison with available experimental data.

  14. Au36(SPh)23 nanomolecules.

    Science.gov (United States)

    Nimmala, Praneeth Reddy; Dass, Amala

    2011-06-22

    A new core size protected completely by an aromatic thiol, Au(36)(SPh)(23), is synthesized and characterized by MALDI-TOF mass spectrometry and UV-visible spectroscopy. The synthesis involving core size changes is studied by MS, and the complete ligand coverage by aromatic thiol group is shown by NMR.

  15. Differential systems of flux and concentrations of a mixture in the separation by a plant (1963); Systemes differente des flux et des concentrations d'un melange en separation par une usine etagee (1963)

    Energy Technology Data Exchange (ETDEWEB)

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

    1963-11-15

    The study of transient flux and concentrations of a mixture in the separation by a plant with different interdependent stages leads to an examination of the solutions of certain types of differential systems. These systems are obtained from the representative graph of the plant and have a structural form. By Olga TAUSSKY's theorem and the introduction of steerable distances, the solutions of these systems are chiefly examined in their asymptotic behaviour. The appendix shows that solutions of partial differential equations relative to plants made of cascades with a slight separation have analogous properties. (author) [French] La recherche des regimes transitoires des flux et des concentrations d'un melange en separation par une usine etagee de forme quelconque conduit a etudier les solutions de certains types de systemes differentiels. Ces systemes sont deduits du graphe representatif de l'usine, et apparaissent sous une forme structuree. A l'aide du theoreme d'Olga TAUSSKY et par l'introduction d'ecarts orientes, les solutions de ces systemes sont principalement examinees dans leur comportement asymptotique. Un appendice montre que les solutions des systemes d'equations aux derivees partielles des usines en cascades a tres faible separation admettent des proprietes analogues. (auteur)

  16. Global polarization measurement in Au+Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev,V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2007-08-02

    The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.

  17. d + Au hadron correlation measurements at PHENIX

    Energy Technology Data Exchange (ETDEWEB)

    Sickles, Anne M., E-mail: anne@bnl.gov

    2014-06-15

    In these proceedings, we discuss recent results from d + Au collisions in PHENIX ridge related measurements and their possible hydrodynamic origin. We present the v{sub 2} at midrapidity and measurements of the pseudorapidity dependence of the ridge, distinguishing between the d-going and Au-going directions. We investigate the possible geometrical origin by comparing v{sub 2} in d + Au to that in p + Pb, Au + Au and Pb + Pb collisions. Future plans to clarify the role of geometry in small collision systems at RHIC are discussed.

  18. Decay spectroscopy of $^{178}$Au

    CERN Document Server

    Whitmore, B

    In this thesis, the neutron-deficient nucleus $^{178}$Au is investigated through decay spectroscopy. Si and HPGe detectors were used to analyse the decay radiation of $^{178}$Au and its daughter nuclei. Previous studies have been unable to distinguish decay radiation from different isomeric states of this nucleus. This thesis represents the first time such isomeric discrimination has been achieved, and presents tentative spin assignments of both the ground state and an isomer. The neutron-deficient gold isotopes are an area of interest for the study of shape coexistence. This is the phenomenon exhibited by nuclei able to exist at a number of close lying energy minima, each reflecting a distinct type of deformation. It is hoped that studies such as this can help identify the evolution of nuclear deformation in this region of the nuclear chart.

  19. Le CRDI au Costa Rica

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

    La stabilité politique du Costa Rica a fait de ce pays un partenaire essen- tiel du CRDI en Amérique centrale pour la recherche portant sur l'agriculture, les politiques économiques, la démocratisation et la prévention des catastrophes naturelles. Le CRDI a beaucoup contribué à la recherche en agriculture au Costa Rica,.

  20. Cas de Cotonou au Benin

    African Journals Online (AJOL)

    Au nombre de ces nuisances, figurent entre autres, la perte de temps et par ricochet d'importantes recettes .... La méthodologie utilisée est basée sur deux types d'approches : l'approche théorique et celle empirique. Le premier volet de ...... Université de Bordeaux Talence, 456 pages. SEGBEDJI, E. (2001) : Impact du trafic ...

  1. L’apprentissage au CERN

    CERN Multimedia

    Staff Association

    2016-01-01

    En 1961, sur la base du constat que l’évolution du marché du travail nécessitait un besoin croissant de personnel qualifié, le 1er accord entre la République et canton de Genève et le CERN fut signé. Cet accord avait notamment pour objet la formation professionnelle de jeunes électroniciens et techniciens de laboratoires en physique. Le CERN, acteur local économique d’importance, soulignait par cet accord sa volonté de participer au développement économique et social local. Le 1er apprenti arriva au CERN en 1965. En 1971, le centre d’apprentissage fut créé ; il accueille aujourd’hui plus d’une vingtaine d’apprentis au total, à raison d’environ six nouveaux apprentis chaque année. Cet apprentissage est dédié aux jeunes âgés e...

  2. Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

    KAUST Repository

    Huang, Jianfeng

    2015-08-13

    Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

  3. Transport characteristics in Au/pentacene/Au diodes

    Science.gov (United States)

    Hayashi, Toshiaki; Naka, Akiyoshi; Hiroki, Masanobu; Yokota, Tomoyuki; Someya, Takao; Fujiwara, Akira

    2018-03-01

    We have used scanning and transmission electron microscopes (SEM and TEM) to study the structure of a pentacene thin film grown on a Au layer with and shown that it consists of randomly oriented amorphous pentacene clusters. We have also investigated the transport properties of amorphous pentacene in a metal–semiconductor–metal (MSM) diode structure and shown that the current is logarithmically proportional to the square root of the applied voltage, which indicates that transport occurs as the result of hopping between localized sites randomly distributed in space and energy.

  4. Acces au traitement anticancereux au Togo (access to treatment of ...

    African Journals Online (AJOL)

    Contexte : Au Togo, l'incidence et la mortalité des cancers ne cessent de croître en raison du diagnostic et de la prise en charge tardifs. D'autres raisons telles que l'absence d'oncologue spécialiste et la faible accessibilité aux médicaments anticancéreux sont de plus en plus évoquées. L'objectif de cette étude était de ...

  5. Application of resistivity measurements to the control of protein elutions using cellulose ion-exchangers; Application de la mesure de resistivite au controle d'une elution de proteines a partir de celluloses echangeuses d'ions

    Energy Technology Data Exchange (ETDEWEB)

    Duplaa, A.M.; Brandolin, G. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    The eluate obtained by chromatography of a mixture of proteins on columns of cellulose ion-exchangers (DEAE-cellulose and CM-cellulose) sometimes have very low proteins concentrations. The resistivity measurement gives more information than the UV control which is often inadequate. The modifications undergone by elution buffers are recorded and the best conditions for the extraction of an enzymatic protein are determined. The tests are performed without proteins on the columns; they consist in a double control of resistivity and ph of elution buffers after they pass on the exchangers columns. (author) [French] Apres chromatographie d'un melange de proteine; sur colonnes d'echangeurs d'ions tels que DEAE-cellulose et CM-cellulose, les eluats obtenus ont quelquefois des concentrations en proteines tres faibles. Au controle en UV souvent insuffisant, on a ajoute la mesure de resistivite apportant des donnees complementaires. Des essais, realises en l'absence de proteines et consistant a effectuer un double controle de resistivite et de pH des tampons d'elution apres leur passage sur colonnes d'echangeurs, ont permis d'enregistrer les modifications subies par ces tampons et de determiner leurs meilleures conditions d'utilisation pour l'extraction d'une proteine enzymatique. (auteur)

  6. High-p(T) Tomography of d+Au and Au+Au at SPS, RHIC, and LHC.

    Science.gov (United States)

    Vitev, Ivan; Gyulassy, Miklos

    2002-12-16

    The interplay of nuclear effects on the p(T)>2 GeV inclusive hadron spectra in d+Au and Au+Au reactions at sqrt[s(NN)]=17, 200, and 5500 GeV is compared to leading order perturbative QCD calculations for elementary p+p (p+p) collisions. The competition between nuclear shadowing, Cronin effect, and jet energy loss due to medium-induced gluon radiation is predicted to lead to a striking energy dependence of the nuclear suppression/enhancement pattern in A+A reactions. We show that future d+Au data can be used to disentangle the initial and final state effects.

  7. Profiling hot and dense nuclear medium with high transverse momentum hadrons produced in d+Au and Au+Au collisions by the PHENIX experiment at RHIC

    Directory of Open Access Journals (Sweden)

    Sakaguchi Takao

    2014-03-01

    Full Text Available PHENIX measurements of high transverse momentum (pT identified hadrons in d+Au and Au+Au collisions are presented. The nuclear modification factors (RdA and RAA for π0 and ƞ are found to be very consistent in both collision systems, respectively. Using large amount of p + p and Au+Au datasets, the fractional momentum loss (Sloss and the path-length dependent yield of π0 in Au+Au collisions are obtained. The hadron spectra in the most central d+Au and the most peripheral Au+Au collisions are studied. The spectra shapes are found to be similar in both systems, but the yield is suppressed in the most peripheral Au+Au collisions.

  8. Au38(SPh)24: Au38 Protected with Aromatic Thiolate Ligands.

    Science.gov (United States)

    Rambukwella, Milan; Burrage, Shayna; Neubrander, Marie; Baseggio, Oscar; Aprà, Edoardo; Stener, Mauro; Fortunelli, Alessandro; Dass, Amala

    2017-04-06

    Au38(SR)24 is one of the most extensively investigated gold nanomolecules along with Au25(SR)18 and Au144(SR)60. However, so far it has only been prepared using aliphatic-like ligands, where R = -SC6H13, -SC12H25 and -SCH2CH2Ph. Au38(SCH2CH2Ph)24 when reacted with HSPh undergoes core-size conversion to Au36(SPh)24, and existing literature suggests that Au38(SPh)24 cannot be synthesized. Here, contrary to prevailing knowledge, we demonstrate that Au38(SPh)24 can be prepared if the ligand exchanged conditions are optimized, under delicate conditions, without any formation of Au36(SPh)24. Conclusive evidence is presented in the form of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), electrospray ionization mass spectra (ESI-MS) characterization, and optical spectra of Au38(SPh)24 in a solid glass form showing distinct differences from that of Au38(S-aliphatic)24. Theoretical analysis confirms experimental assignment of the optical spectrum and shows that the stability of Au38(SPh)24 is not negligible with respect to that of its aliphatic analogous, and contains a significant component of ligand-ligand attractive interactions. Thus, while Au38(SPh)24 is stable at RT, it converts to Au36(SPh)24 either on prolonged etching (longer than 2 hours) at RT or when etched at 80 °C.

  9. Genre et migration au Maroc

    OpenAIRE

    KHACHANI, Mohamed

    2011-01-01

    Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) Une des principales caractéristiques récentes de la migration marocaine est sa tendance à une féminisation soutenue. Le projet migratoire - qui était un projet d’hommes - intéresse de plus en plus les femmes marocaines au point de constituer actuellement près de la moitié de l’effectif migratoire marocain. Cette reconnaissance de l'importance des femmes dans la construction de l'espace migratoire a placé ...

  10. Genre et migration au Liban

    OpenAIRE

    JOUNI, Hassan

    2011-01-01

    Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) La femme possède un statut bien avancé au sein de la société libanaise : la Constitution libanaise proclame l’égalité entre les citoyens. Quelques lois et pratiques restent, toutefois, discriminatoires à l’égard de la femme, notamment la loi sur la nationalité et la loi sur le statut personnel. Une discrimination sociale très grave existe en ce qui concerne les femmes travaillant à domicile; elles subi...

  11. Nuclear Data Sheets for 181Au

    Science.gov (United States)

    Baglin, Coral M.

    1999-06-01

    Nuclear structure data pertaining to 181Au have been compiled and evaluated, and incorporated into the ENSDF data file. This evaluation of 181Au supersedes the previous publication (R. B. Firestone, Nuclear Data Sheets 62, 101 (1991) (literature cutoff date October 1990)), and includes literature available by 2 July 1999. The newly incorporated references are: 1999Mu05, 1999So01, 1995Au04, 1995Bi01, 1991Ry01, 1979Ha10, 1970Ha18.

  12. Nuclear data sheets for 181Au

    Energy Technology Data Exchange (ETDEWEB)

    Baglin, Coral M.

    1999-07-02

    Nuclear structure data pertaining to 181Au have been compiled and evaluated, and incorporated into the ENSDF data file. This evaluation of 181Au supersedes the previous publication (R. B. Firestone, Nuclear Data Sheets 62, 101 (1991) (literature cutoff date October 1990)), and includes literature available by 2 July 1999. The newly incorporated references are: 1999Mu05, 1999So01, 1995Au04, 1995Bi01, 1991Ry01, 1979Ha10, 1970Ha18.

  13. Predicted Habitat Suitability for Montipora Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Montipora in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  14. Predicted Habitat Suitability for Porites in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Porites in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  15. Predicted Habitat Suitability for Porites Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Porites in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  16. Predicted Habitat Suitability for Leptoseris Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Leptoseris in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  17. Predicted Habitat Suitability for All Mesophotic Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for all mesophotic corals in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to...

  18. Predicted Habitat Suitability for Leptoseris in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Leptoseris in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  19. Predicted Habitat Suitability for All Mesophotic Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is located between the islands of Maui, Lanai, Molokai and Kahoolawe, and includes the Au'au Channel as well as parts of the Kealaikahiki, Alalakeiki...

  20. PHENIX results on collectivity in high-multiplicity p + Au, d + Au and 3He + Au collisions

    Science.gov (United States)

    Xu, Qiao

    2016-08-01

    We present recent PHENIX results for long-range two-particle correlation functions across a large pseudorapidity(η) gap in high-multiplicity p+Au, d+Au and 3He+Au collisions. Enhanced correlations are observed for particles with small azimuthal separation. Measurements of the second order Fourier coefficients (v 2) in p/d/3He+Au collisions, and the third order Fourier coefficient (v 3) in 3He+Au collision are performed using the event plane method. Scaling of v 2 with the initial eccentricity (ɛ 2) is performed in each system to investigate the role of the initial geometry in the development of a final-state anisotropy in the particle emission. The v 2 coefficients for identified π±, K± and (anti-)proton are measured as a function of transverse kinetic energy (KET) and their magnitudes are found to scale approximately with the number of constituent quarks in the hadron.

  1. Comparative study of anchoring groups for molecular electronics: structure and conductance of Au-S-Au and Au-NH{sub 2}-Au junctions

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, I S; Mowbray, D J; Thygesen, K S; Jacobsen, K W [Center for Atomic-scale Materials Design (CAMD), Department of Physics, Building 307, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)

    2008-09-17

    The electrical properties of single-molecule junctions, consisting of an organic molecule coupled to metal electrodes, are sensitive to the detailed atomic structure of the molecule-metal contact. This, in turn, is determined by the anchoring group linking the molecule to the metal. With the aim of identifying and comparing the intrinsic properties of two commonly used anchoring groups, namely thiol and amine groups, we have calculated the atomic structure and conductance traces of different Au-S-Au and Au-NH{sub 2}-Au nanojunctions using density functional theory (DFT). Whereas NH{sub 2} shows a strong structural selectivity towards atop-gold configurations, S shows large variability in its bonding geometries. As a result, the conductance of the Au-NH{sub 2}-Au junction is less sensitive to the structure of the gold contacts than the Au-S-Au junction. These findings support recent experiments which show that amine-bonded molecules exhibit more well-defined conductance properties than do thiol-bonded molecules.

  2. Travailler avec Windows 7 au CERN (FR)

    CERN Multimedia

    CERN. Geneva

    2010-01-01

    Vue d'ensemble des nouveaux concepts et des changements dans l'interface utilisateur survenus dans Windows 7 depuis les versions antérieures de Windows (XP ou Vista). La mise à disposition de Windows 7 au CERN et son intégration dans l’infrastructure de Windows au CERN seront présentées.

  3. English for au pairs the au pair's guide to learning English

    CERN Document Server

    Curtis, Lucy

    2014-01-01

    English for Au Pairs has interlinked stories about a group of au pairs new to England. Marta, an 18-year-old from Poland arrives in the UK to work as an au pair. Throughout her year-long stay she has many different experiences - some bad, some good - but with the support of her host family she finds new friends and improves her English. English for Au Pairs offers insight into the joys and difficulties of being an au pair while at the same time reinforcing English language learning through grammar explanations and exercises.

  4. Au microstructure and the functional properties of Ni/Au finishes on ceramic IC packages

    Energy Technology Data Exchange (ETDEWEB)

    Winters, E.D.; Baxter, W.K. [Coors Electronic Package Co., Chattanooga, TN (United States); Braski, D.N.; Watkins, T.R. [Oak Ridge National Lab., TN (United States)

    1995-12-31

    Ni/Au plated finishes used on thick-film metallized multilayer ceramic packages for integrated circuits must meet functional requirements such as bondability, sealability, and solderability. Their ability to do so is dependent, among other things, on the ability of the Au deposit to inhibit the grain boundary diffusion and subsequent surface oxidation of Ni. In this study, the relation between functional performance, Ni diffusionr ate, and Au microstructure was examined. Extent of Ni diffusion during heating was determined by Auger electron spectroscopy for several electrolytic and electroless Ni/Au finishing processes. Results were correlated with differences in Au microstructures determined by SEM, atomic force microscopy, and XRD.

  5. AU-EU “Strategic Partnership”

    DEFF Research Database (Denmark)

    Rodt, Annemarie Peen; Okeke, Jide

    2013-01-01

    This article appraises strategic partnership between the African Union (AU) and European Union (EU). It examines the context and nature of AU and EU security relations and explores the conditions under which partnership has a positive impact in this regard. This includes an evaluation of converge......This article appraises strategic partnership between the African Union (AU) and European Union (EU). It examines the context and nature of AU and EU security relations and explores the conditions under which partnership has a positive impact in this regard. This includes an evaluation...... of convergence between the two organizations and its effect or lack thereof on African security. The article concludes that events leading up to and initiatives following the 2007 Joint Africa–European Union Strategy have produced a degree of AU and EU convergence, which has had limited impact on the efficacy...

  6. Structure of the thiolated Au130 cluster.

    Science.gov (United States)

    Tlahuice-Flores, Alfredo; Santiago, Ulises; Bahena, Daniel; Vinogradova, Ekaterina; Conroy, Cecil V; Ahuja, Tarushee; Bach, Stephan B H; Ponce, Arturo; Wang, Gangli; José-Yacamán, Miguel; Whetten, Robert L

    2013-10-10

    The structure of the recently discovered Au130-thiolate and -dithiolate clusters is explored in a combined experiment-theory approach. Rapid electron diffraction in scanning/transmission electron microscopy (STEM) enables atomic-resolution imaging of the gold core and the comparison with density functional theory (DFT)-optimized realistic structure models. The results are consistent with a 105-atom truncated-decahedral core protected by 25 short staple motifs, incorporating disulfide bridges linking the dithiolate ligands. The optimized structure also accounts, via time-dependent DFT (TD-DFT) simulation, for the distinctive optical absorption spectrum, and rationalizes the special stability underlying the selective formation of the Au130 cluster in high yield. The structure is distinct from, yet shares some features with, each of the known Au102 and Au144/Au146 systems.

  7. Gas-phase experiments on Au(III) photochemistry.

    Science.gov (United States)

    Marcum, Jesse C; Kaufman, Sydney H; Weber, J Mathias

    2011-04-14

    Irradiation of AuCl(4)(-) and AuCl(2)(OH)(2)(-) in the gas-phase using ultraviolet light (220-415 nm) leads to their dissociation. Observed fragment ions for AuCl(4)(-) are AuCl(3)(-) and AuCl(2)(-) and for AuCl(2)(OH)(2)(-) are AuCl(2)(-) and AuClOH(-). All fragment channels correspond to photoreduction of the gold atom to either Au(II) or Au(I) depending on the number of neutral ligands lost. Fragment branching ratios of AuCl(4)(-) are observed to be highly energy dependent and can be explained by comparison of the experimental data to calculated threshold energies obtained using density functional theory. The main observed spectral features are attributed to ligand-to-metal charge transfer transitions. These results are discussed in the context of the molecular-level mechanisms of Au(III) photochemistry.

  8. Magnetic depth profiling of Fe/Au multilayer using neutron ...

    Indian Academy of Sciences (India)

    Au multilayer sample for characterizing the layer structure and magnetic moment density profile. Fe/Au multilayer shows strong spin-dependent scattering at interfaces, making it a prospective GMR material. Fe/Au multilayer with bilayer ...

  9. Contribution to the study and to the development of continuous infrared absorption analyzers; Contribution a l'etude et a la mise au point des analyseurs en continu par absorption infrarouge

    Energy Technology Data Exchange (ETDEWEB)

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

    1967-12-01

    The continuous infra-red absorption determination of corrosive gases implies the construction of an original single-beam spectrometer. The use of a vibration-rotation line means that the apparatus function has to undergo an alternating displacement: for one position this function is centered on the line, for other position it is placed close by, but away from any absorption. A non-linear relationship is derived between the concentration of the impurity under consideration, the optical density measured at the centre of the line and the total pressure of the gas mixture. The problem is then solved using an associated specific analog computer. The system is applicable to the determination of low concentrations. The principle proposed in then adapted to an analysis using a non-resolved vibration-rotation band. (authors) [French] Le dosage en continu par absorption infrarouge des gaz corrosifs, implique la construction d'un spectrometre original en simple faisceau. L'utilisation d'une raie de vibration - rotation, conduit a effectuer un deplacement alternatif de la fonction d'appareil: pour une position, celle-ci est centree sur la raie, pour l'autre position elle est placee a proximite mais en dehors de toute absorption. On etablit une relation non lineaire entre la concentration de l'impurete consideree, la densite optique mesuree au centre de la raie et la pression totale du melange gazeux. Le probleme est alors resolu par un calculateur analogique specifique associe. Le systeme s'applique au dosage des faibles concentrations. Le principe propose est ensuite adapte a l'analyse a partir d'une bande de vibration - rotation non resolue. (auteurs)

  10. Au dissolution during the anodic response of short-chain alkylthiols with polycrystalline Au electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Scott R. [Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Guerra, Eduard [School of Engineering, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Siemann, Stefan [Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Shepherd, Jeffrey L., E-mail: jshepherd@laurentian.ca [Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada)

    2011-10-01

    Highlights: > 3-Mercaptopropionic acid (MPA) or meso-2,3-dimercaptosuccinic acid (DMSA) mediated Au corrosion in aqueous electrolytes at anodic potentials. > Au is roughened and passivated by an insoluble Au-MPA product. > Au is leached into the aqueous electrolyte as a soluble Au-DMSA species ({approx}60 ppb, 12 h). - Abstract: The electrochemical characteristics of polycrystalline Au in LiClO{sub 4} electrolyte solutions containing 3-mercaptopropionic acid (MPA) or meso-2,3-dimercaptosuccinic acid (DMSA) were studied with linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) over a wide range of positive potentials vs. Ag/AgCl. The EIS data exhibited linear capacitive behaviour at 0.0 V with either MPA or DMSA added directly to the electrolyte suggesting the formation of an adsorbed layer of the alkylthiol on the electrode surface. Above this potential, a single well-defined impedance loop appeared for electrolyte solutions containing DMSA or MPA, an observation indicative of a charge transfer reaction that could be related to several processes including oxidative desorption, oxidation of the alkylthiol, or Au oxidation/dissolution. To test for Au dissolution, the electrode was held at 0.8 V vs. Ag/AgCl for 12 h in electrolytes containing MPA or DMSA followed by surface analysis with Atomic Force Microscopy and solution analysis with Atomic Absorption Spectroscopy. When the electrolyte contained MPA, the extended potential holding procedure resulted in significant roughening of the electrode with no detectable quantities of Au in the electrolyte. X-ray photoelectron spectroscopy (XPS) analysis of the Au surface revealed an additional species in the Au 4f{sub 7/2} spectrum indicating the presence of an insoluble electrochemically generated Au(I)-MPA species. When the electrolyte contained DMSA, the Au electrode appeared smoother, 56.6 {+-} 9.6 ppb of Au was detected in the electrolyte and the XPS analysis displayed a single species in the

  11. Au/Au@polythiophene core/shell nanospheres for heterogeneous catalysis of nitroarenes.

    Science.gov (United States)

    Shin, Hye-Seon; Huh, Seong

    2012-11-01

    Monodisperse Au/Au@polythiophene core/shell nanospheres were facilely prepared through the reduction of gold precursor, AuCl₄⁻, by 2-thiopheneacetonitrile in an aqueous solution. Concomitantly, 2-thiopheneacetonitrile polymerized during this redox process. As a result, Au nanoparticle was encapsulated by conductive polymer shell to afford novel core/shell nanospheres. Interestingly, the shell was composed of very tiny Au nanoparticles surrounded with thiophene polymers. Thus, the new material is best described as Au/Au@polythiophene core/shell nanospheres. FT-IR spectroscopy revealed that the Au nanoparticles were coordinated by the C≡N groups of the polythiophene shell. Some of the C≡N groups were partially hydrolyzed into COOH groups during the redox process because of the acidic reaction condition. The shell was conductive based on the typical ohmic behavior found in electrical measurement. The Au/Au@polythiophene core/shell nanospheres were found to be very active catalysts for the hydrogenation of various nitroarene compounds into corresponding aminoarene compounds in the presence of NaBH₄. Both hydrophilic and hydrophobic nitroarenes were efficiently hydrogenated under mild conditions.

  12. Filipino au pairs on the move

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    interdependence, whilst they continuously form their trajectories in relation to opportunities and restraints posed along the way by their local and transnational social relations. The article argues that examinations of migration trajectories benefit from broadening the research out in both time and space......Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial...

  13. Becoming independent through au pair migration

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    . This article argues that, despite this critique, au pairing does play an important formative role for young Filipinas because it opens up for experiences abroad that enable them to be recognised as independent adults in Philippine society. Rather than autonomy, however, au pairs define their independence...... in terms of their capacity to assume responsibility for others, thereby achieving a position of social respect. Based on ethnographic fieldwork in Denmark and the Philippines, this article explores how young Filipinas use the social, economic, and cultural resources they gain from their au pair stay abroad...

  14. Synthesis of ultrathin face-centered-cubic Au@Pt and Au@Pd core-shell nanoplates from hexagonal-close-packed Au square sheets

    KAUST Repository

    Fan, Zhanxi

    2015-03-17

    The synthesis of ultrathin face-centered-cubic (fcc) Au@Pt rhombic nanoplates is reported through the epitaxial growth of Pt on hexagonal-close-packed (hcp) Au square sheets (AuSSs). The Pt-layer growth results in a hcp-to-fcc phase transformation of the AuSSs under ambient conditions. Interestingly, the obtained fcc Au@Pt rhombic nanoplates demonstrate a unique (101)f orientation with the same atomic arrangement extending from the Au core to the Pt shell. Importantly, this method can be extended to the epitaxial growth of Pd on hcp AuSSs, resulting in the unprecedented formation of fcc Au@Pd rhombic nanoplates with (101)f orientation. Additionally, a small amount of fcc (100)f-oriented Au@Pt and Au@Pd square nanoplates are obtained with the Au@Pt and Au@Pd rhombic nanoplates, respectively. We believe that these findings will shed new light on the synthesis of novel noble bimetallic nanostructures. Phase change: Ultrathin Au@Pt and Au@Pd core-shell nanoplates were prepared from Au square sheets. A phase transformation from hexagonal close-packed (hcp) to face-centered cubic (fcc) is observed upon coating the hcp Au square sheets with Pt or Pd under ambient conditions. The prepared fcc Au@Pt and Au@Pd rhombic nanoplates demonstrate unique (101)f orientation (picture shows a typical fcc Au@Pt rhombic nanoplate). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Et pourquoi pas au CERN ?

    CERN Multimedia

    Staff Association

    2015-01-01

    Télétravail ou travail à distance, aménagement des horaires de travail et autres évolutions favorables à un meilleur équilibre vie privée et vie professionnelle sont adoptés par nombre d’entreprises et d’organisations !   Rendu possible grâce au développement de nouvelles technologies dont Internet, le travail à distance séduit de plus en plus de personnels, ainsi que de plus en plus de sociétés qui y trouvent des avantages en matière de gestion de l’espace, de sécurité (moins de trajets domicile-entreprise), de développement durable (moins de pollution), de motivation et de bien-être de leurs personnels. Les horaires aménagés, voire les « core-hours1 », sont également des pratiques de plus e...

  16. Comparative efficiencies of photothermal destruction of malignant cells using antibody-coated silica-Au nanoshells, hollow Au/Ag nanospheres and Au nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Fong-Yu; Chen, Chen-Tai; Yeh, Chen-Sheng, E-mail: csyeh@mail.ncku.edu.t [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China)

    2009-10-21

    Three Au-based nanomaterials (silica-Au nanoshells, hollow Au/Ag nanospheres and Au nanorods) were evaluated for their comparative photothermal efficiencies at killing three types of malignant cells (A549 lung cancer cells, HeLa cervix cancer cells and TCC bladder cancer cells) using a CW NIR laser. Photodestructive efficiency was evaluated as a function of the number of nanoparticles required to destroy the cancer cells under 808 nm laser wavelength at fixed laser power. Of the three nanomaterials, silica/Au nanoshells needed the minimum number of particles to produce effective photodestruction, whereas Au nanorods needed the largest number of particles. Together with the calculated photothermal conversion efficiency, the photothermal efficiency rankings are silica-Au nanoshells > hollow Au/Ag nanospheres > Au nanorods. Additionally, we found that HeLa cells seem to present better heat tolerance than the other two cancer cell lines.

  17. Initial Eccentricity in Deformed 197Au+197Au and 238U+238U Collisions at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Filip, Peter; Lednicky, Richard; Masui, Hiroshi; Xu, Nu

    2010-07-07

    Initial eccentricity and eccentricity fluctuations of the interaction volume created in relativistic collisions of deformed {sup 197}Au and {sup 238}U nuclei are studied using optical and Monte-Carlo (MC) Glauber simulations. It is found that the non-sphericity noticeably influences the average eccentricity in central collisions and eccentricity fluctuations are enhanced due to deformation. Quantitative results are obtained for Au+Au and U+U collisions at energy {radical}s{sub NN} = 200 GeV.

  18. Photovoltage responses of graphene-Au heterojunctions

    Science.gov (United States)

    Li, Kai; Ying, Xiangxiao; Wang, Juan; Wang, Jun; Jiang, Yadong; Liu, Zhijun

    2017-10-01

    As an emerging 2D material, graphene's several unique properties, such as high electron mobility, zero-bandgap and low density of states, present new opportunities for light detections. Here, we report on photovoltage responses of graphene-Au heterojunctions, which are made of monolayer graphene sheets atop Au electrodes designed as finger-shape and rectangle-shape, respectively. Besides confirming the critical role of space charge regions located at the graphene-Au boundary, photovoltage responses are measured in the visible to infrared spectral region with a cut-off wavelength at about 980 nm, which is likely imposed by the Pauli blocking of interband transition in the contact-doped graphene. The photoresponsivity is shown to decrease with increasing wavelength. A band diagram of the graphene-Au heterojunction is proposed to understand the photoresponse mechanism.

  19. Intense fluorescence of Au 20

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chongqi; Harbich, Wolfgang; Sementa, Luca; Ghiringhelli, Luca; Apra, Edoardo; Stener, Mauro; Fortunelli, Alessandro; Brune, Harald

    2017-08-21

    Ligand-protected Au clusters are non-bleaching fluorescence markers in bio- and medical applications. We show that their fluorescence is an intrinsic property of the Au cluster itself. We find a very intense and sharp fluorescence peak located at λ =739.2 nm (1.68 eV) for Au20 clusters in a Ne matrix held at 6 K. The fluorescence reflects the HOMO-LUMO diabatic bandgap of the cluster. The cluster shows a very rich absorption fine structure reminiscent of well defined molecule-like quantum levels. These levels are resolved since Au20 has only one stable isomer (tetrahedral), therefore our sample is mono-disperse in cluster size and conformation. Density-functional theory (DFT) and time-dependent DFT calculations clarify the nature of optical absorptionand predict both main absorption peaks and intrinsic fluorescence in good agreement with experiment.

  20. PHENIX results on jets in d + Au

    Science.gov (United States)

    Hanks, J. Ali

    2016-12-01

    We present recently published results [A. Adare, et al., arxiv:arXiv:1509.04657] on fully reconstructed R=0.3 anti-kt jets measured in p+p and d+Au collisions at 200 GeV center-of-mass energy. The jet yields for four centrality classes along with the p+p reference are presented, as well as both the minimum bias RdAu and centrality dependent RdAu and RCP. We find that while the minimum bias RdA is consistent with unity, providing a strong constraint on models including cold-nuclear-matter effects or energy loss in small systems, the centrality dependent RdAu show a striking variation which presents a challenge to models attempting to describe the interplay between soft and hard processes in these systems.

  1. 22 CFR 62.31 - Au pairs.

    Science.gov (United States)

    2010-04-01

    ....31 Au pairs. (a) Introduction. This section governs Department of State-designated exchange visitor... requirements set forth at § 62.10 sponsors shall: (1) Inform all host families of the philosophy, rules, and...

  2. Unravelling Thiol’s Role in Directing Asymmetric Growth of Au Nanorod–Au Nanoparticle Dimers

    KAUST Repository

    Huang, Jianfeng

    2015-12-15

    Asymmetric nanocrystals have practical significance in nanotechnologies but present fundamental synthetic challenges. Thiol ligands have proven effective in breaking the symmetric growth of metallic nanocrystals but their exact roles in the synthesis remain elusive. Here, we synthesized an unprecedented Au nanorod-Au nanoparticle (AuNR-AuNP) dimer structure with the assistance of a thiol ligand. On the basis of our experimental observations, we unraveled for the first time that the thiol could cause an inhomogeneous distribution of surface strains on the seed crystals as well as a modulated reduction rate of metal precursors, which jointly induced the asymmetric growth of monometallic dimers. © 2015 American Chemical Society.

  3. "Dealloying" Phase Separation during Growth of Au on Ni(110)

    DEFF Research Database (Denmark)

    Nielsen, L. Pleth; Besenbacher, Flemming; Stensgaard, I.

    1995-01-01

    Combined scanning tunneling microscopy and ion-scattering studies have revealed a new "dealloying" phase transition during the growth of Au on Ni(110). The Au atoms, which initially alloy into the Ni(110) surface, phase separate into a vacancy-stabilized Au dimer-trimer chain structure at Au...

  4. Enantioselective separation on chiral Au nanoparticles.

    Science.gov (United States)

    Shukla, Nisha; Bartel, Melissa A; Gellman, Andrew J

    2010-06-30

    The surfaces of chemically synthesized Au nanoparticles have been modified with d- or l-cysteine to render them chiral and enantioselective for adsorption of chiral molecules. Their enantioselective interaction with chiral compounds has been probed by optical rotation measurements during exposure to enantiomerically pure and racemic propylene oxide. The ability of optical rotation to detect enantiospecific adsorption arises from the fact that the specific rotation of polarized light by (R)- and (S)-propylene oxide is enhanced by interaction with Au nanoparticles. This effect is related to previous observations of enhanced circular dichroism by Au nanoparticles modified by chiral adsorbates. More importantly, chiral Au nanoparticles modified with either d- or l-cysteine selectively adsorb one enantiomer of propylene oxide from a solution of racemic propylene oxide, thus leaving an enantiomeric excess in the solution phase. Au nanoparticles modified with l-cysteine (d-cysteine) selectively adsorb the (R)-propylene oxide ((S)-propylene oxide). A simple model has been developed that allows extraction of the enantiospecific equilibrium constants for (R)- and (S)-propylene oxide adsorption on the chiral Au nanoparticles.

  5. Apprentissages techniques : L'apprentissage au CERN

    CERN Document Server

    2004-01-01

    APPRENTISSAGES TECHNIQUES GESTION ET DEVELOPPEMENT DU PERSONNEL HR/PMD L'APPRENTISSAGE AU CERN pour les professions d'électronicien(ne) et de laborantin(e) en physique L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 7 places au total sont ouvertes au recrutement pour les deux professions. L'apprentissage dure 4 ans. Minima requis pour faire acte de candidature : • avoir au moins 15 ans et moins de 21 ans à la date de début de l'apprentissage • avoir terminé la scolarité obligatoire, au minimum 9ème du Cycle d'orientation genevois (3ème en France) • être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgiqu...

  6. Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2009-04-11

    Identified charged particle spectra of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} at mid-rapidity (|y| < 0.1) measured by the dE/dx method in the STAR-TPC are reported for pp and d + Au collisions at {radical}s{sub NN} = 200 GeV and for Au + Au collisions at 62.4 GeV, 130 GeV, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm{sub 3} for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters due to the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase

  7. Fully Cationized Gold Clusters: Synthesis of Au25(SR+)18.

    Science.gov (United States)

    Ishida, Yohei; Narita, Kunihiro; Yonezawa, Tetsu; Whetten, Robert L

    2016-10-06

    Although many thiolate-protected Au clusters with different numbers of Au atoms and a variety of thiolate ligands have been synthesized, to date there has been no report of a fully cationized Au cluster protected with cationic thiolates. Herein, we report the synthesis of the first member of a new series of thiolate-protected Au cluster molecules: a fully cationized Au 25 (SR + ) 18 cluster.

  8. Suppression of ϒ production in d+Au and Au+Au collisions at √(s{sub NN})=200 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L. [AGH University of Science and Technology, Cracow (Poland); Adkins, J.K. [University of Kentucky, Lexington, KY, 40506-0055 (United States); Agakishiev, G. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Aggarwal, M.M. [Panjab University, Chandigarh 160014 (India); Ahammed, Z. [Variable Energy Cyclotron Centre, Kolkata 700064 (India); Alekseev, I. [Alikhanov Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Alford, J. [Kent State University, Kent, OH 44242 (United States); Anson, C.D. [Ohio State University, Columbus, OH 43210 (United States); Aparin, A. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Arkhipkin, D.; Aschenauer, E.C. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Averichev, G.S. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Balewski, J. [Massachusetts Institute of Technology, Cambridge, MA 02139-4307 (United States); Banerjee, A. [Variable Energy Cyclotron Centre, Kolkata 700064 (India); Barnovska, Z. [Nuclear Physics Institute AS CR, 250 68 Řež/Prague (Czech Republic); Beavis, D.R. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Bellwied, R. [University of Houston, Houston, TX, 77204 (United States); Bhasin, A. [University of Jammu, Jammu 180001 (India); Bhati, A.K. [Panjab University, Chandigarh 160014 (India); Bhattarai, P. [University of Texas, Austin, TX 78712 (United States); and others

    2014-07-30

    We report measurements of ϒ meson production in p+p, d+Au, and Au+Au collisions using the STAR detector at RHIC. We compare the ϒ yield to the measured cross section in p+p collisions in order to quantify any modifications of the yield in cold nuclear matter using d+Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p+p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for ϒ(1S+2S+3S) in the rapidity range |y|<1 in d+Au collisions of R{sub dAu}=0.79±0.24(stat.)±0.03(syst.)±0.10(p+p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au+Au collisions, we measure a nuclear modification factor of R{sub AA}=0.49±0.1(stat.)±0.02(syst.)±0.06(p+psyst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state ϒ mesons in Au+Au collisions. The additional suppression in Au+Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d+Au is still needed before any definitive statements about the nature of the suppression in Au+Au can be made.

  9. 100-MeV proton beam intensity measurement by Au activation analysis using {sup 197}Au(p, pn){sup 196}Au and {sup 197}Au(p, p3n){sup 194}Au reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari Oranj, Leila [Division of Advanced Nuclear Engineering, POSTECH, Pohang 37673 (Korea, Republic of); Jung, Nam-Suk; Oh, Joo-Hee [Pohang Accelerator Laboratory, POSTECH, Pohang 37673 (Korea, Republic of); Lee, Hee-Seock, E-mail: lee@postech.ac.kr [Pohang Accelerator Laboratory, POSTECH, Pohang 37673 (Korea, Republic of)

    2016-05-15

    The proton beam intensity of a 100-MeV proton linac at the Korea Multi-purpose Accelerator Complex (KOMAC) was measured by an Au activation analysis using {sup 197}Au(p, pn){sup 196}Au and {sup 197}Au(p, p3n){sup 194}Au reactions to determine the accuracy and precision of beam intensity measurement using Gafchromic film dosimetry method. The target, irradiated by 100-MeV protons, was arranged in a stack consisting of Au, Al foils and Pb plates. The yields of produced radio-nuclei in Au foils were obtained by gamma-ray spectroscopy. The FLUKA code was employed to calculate the energy spectrum of protons onto the front surface of Au foils located at three different depth points of the target and also to investigate the condition of incident beam on the target. A good agreement was found between the beam intensity measurements using the activation analysis method at three different depth points of the target. An excellent agreement was also observed between the beam intensity measurements using the Au activation analysis method and the dosimetry method using Gafchromic film.

  10. Toward hybrid Au nanorods @ M (Au, Ag, Pd and Pt) core-shell heterostructures for ultrasensitive SERS probes

    Science.gov (United States)

    Xie, Xiaobin; Gao, Guanhui; Kang, Shendong; Lei, Yanhua; Pan, Zhengyin; Shibayama, Tamaki; Cai, Lintao

    2017-06-01

    Being able to precisely control the morphologies of noble metallic nanostructures is of essential significance for promoting the surface-enhanced Raman scattering (SERS) effect. Herein, we demonstrate an overgrowth strategy for synthesizing Au @ M (M = Au, Ag, Pd, Pt) core-shell heterogeneous nanocrystals with an orientated structural evolution and highly improved properties by using Au nanorods as seeds. With the same reaction condition system applied, we obtain four well-designed heterostructures with diverse shapes, including Au concave nanocuboids (Au CNs), Au @ Ag crystalizing face central cube nanopeanuts, Au @ Pd porous nanocuboids and Au @ Pt nanotrepangs. Subsequently, the exact overgrowth mechanism of the above heterostructural building blocks is further analysed via the systematic optimiziation of a series of fabrications. Remarkably, the well-defined Au CNs and Au @ Ag nanopeanuts both exhibit highly promoted SERS activity. We expect to be able to supply a facile strategy for the fabrication of multimetallic heterogeneous nanostructures, exploring the high SERS effect and catalytic activities.

  11. Leading Hadron Production in d+Au and 3He+Au collisions in the PHENIX experiment

    Science.gov (United States)

    Sakaguchi, Takao; Phenix Collaboration

    2017-08-01

    Neutral pions have been measured in 3He+Au collisions at √{sNN } = 200 GeV up to 20 GeV/c in the RHIC Year-2014 run. The nuclear modification factor RAA was measured and compared with that from d+Au collisions. The integrated RAA as a function of Npart was calculated for d+Au, 3He+Au and Au+Au collisions at √{sNN } = 200 GeV, and found to converge for Npart > 12, while a clear system ordering RdAu >RHeAu >RAuAu was observed for Npart > 12. The fractional momentum loss for the most central 3He+Au collisions was also estimated.

  12. INDRA at GSI; INDRA au GSI

    Energy Technology Data Exchange (ETDEWEB)

    Bougault, R.; Bocage, F.; Durand, D.; Lopez, O.; Steckmeyer, J.C.; Tamain, B.; Vient, E. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France); Collaboration INDRA: IPN-Orsay, DAPNIA-Saclay, SUBATECH-Nantes, IPN- Lyon, GANIL-Caen

    1997-12-31

    In connection to the decision of installing the INDRA detector by the SIS synchrocyclotron at GSI (Darmstadt, Germany) the report presents the tasks taken into account by the LPC-Caen. These refer to the detector displacement and (mechanical) installation at GSI, the tests before beam (i.e. electronics acquisition software, detectors, etc.) as well as the data acquisition and processing. The physical pro-arguments mention the possibility of disposing of heavy ion beams in a range from 50 MeV to several GeV/nucleon so extending the study of multifragmentation done at GANIL between 30 and 90 MeV/nucleon. More specific, the scientific program of INDRA at GSI inserts studies between those done at around Fermi energy, were the reaction mechanisms are of type of deep inelastic scattering/incomplete fusion, and the studies in the relativistic energy domain where the individual properties of nucleons and transparency of nuclear matter implies mechanisms of the participant-spectator type (fire-ball creation). Also mentioned as fields of extensive studies are: the multifragmentation and its fundamental relation with the nuclear matter equation of state, the role of reaction dynamics in the appearance of collective effects of the radial flow type and its relations with the nuclear compressibility and phase transitions and the thermodynamics of nuclear matter. It appeared that the heavy systems Xe + Sn and Au + Au are the best compromise for the different topics to be approached. The bombarding energies extend from 50 to 150 MeV/nucleon. The report ends with the table giving for six heavy systems (Xe + Sn, Au + Au, C + Au, Ar + Au and P + Au) the required bombarding energies 15 refs.

  13. The extraction characteristic of Au-Ag from Au concentrate by thiourea solution

    Science.gov (United States)

    Kim, Bongju; Cho, Kanghee; On, Hyunsung; Choi, Nagchoul; Park, Cheonyoung

    2013-04-01

    The cyanidation process has been used commercially for the past 100 years, there are ores that are not amenable to treatment by cyanide. Interest in alternative lixiviants, such as thiourea, halogens, thiosulfate and malononitrile, has been revived as a result of a major increase in gold price, which has stimulated new developments in extraction technology, combined with environmental concern. The Au extraction process using the thiourea solvent has many advantages over the cyanidation process, including higher leaching rates, faster extraction time and less than toxicity. The purpose of this study was investigated to the extraction characteristic of Au-Ag from two different Au concentrate (sulfuric acid washing and roasting) under various experiment conditions (thiourea concentration, pH of solvent, temperature) by thiourea solvent. The result of extraction experiment showed that the Au-Ag extraction was a fast extraction process, reaching equilibrium (maximum extraction rate) within 30 min. The Au-Ag extraction rate was higher in the roasted concentrate than in the sulfuric acid washing. The higher the Au-Ag extraction rate (Au - 70.87%, Ag - 98.12%) from roasted concentrate was found when the more concentration of thiourea increased, pH decreased and extraction temperature increased. This study informs extraction method basic knowledge when thiourea was a possibility to eco-/economic resources of Au-Ag utilization studies including the hydrometallurgy.

  14. Multistep production of eta and hard pi(0) mesons in subthreshold Au-Au collisions

    NARCIS (Netherlands)

    Appenheimer, M; Averbeck, R; Charbonnier, Y; Diaz, J; Doppenschmidt, A; Hejny, [No Value; Hlavac, S; Holzmann, R; Kugler, A; Lohner, H; Marin, A; Metag, [No Value; Novotny, R; Ostendorf, RW; Pleskac, R; Schubert, A; Schutz, Y; Simon, RS; Stratmann, R; Stroher, H; Tlusty, P; Vogt, PH; Wagner, [No Value; Weiss, J; Wilschut, HW; Wissmann, F; Wolf, M

    1998-01-01

    The neutral pi(o) and eta mesons are studied in Au-197-Au-197 collisions at an incident energy of 800A MeV, substantially below the threshold for eta production in N-N collisions. While the gross pi(o) multiplicity increases almost linearly with the number of participant nucleons, the multiplicities

  15. Au/ZnO nanoarchitectures with Au as both supporter and antenna of visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tianyu; Chen, Wei; Hua, Yuxiang; Liu, Xiaoheng, E-mail: xhliu@mail.njust.edu.cn

    2017-01-15

    Highlights: • An inversed Au/ZnO nanostructure was fabricated with ZnO loaded onto Au. • The Au/ZnO nanocomposites showed enhanced properties in visible-light photocatalysis. • The SPR effect of Au was considered important for visible-light photocatalysis. - Abstract: In this paper, we fabricate Au/ZnO nanostructure with smaller ZnO nanoparticles loaded onto bigger gold nanoparticles via combining seed-mediated method and sol-gel method. The obtained Au/ZnO nanocomposites exhibit excellent properties in photocatalysis process like methyl orange (MO) degradation and oxidative conversion of methanol into formaldehyde under visible light irradiation. The enhanced properties were ascribed to the surface plasmon resonance (SPR) effect of Au nanoparticles, which could contribute to the separation of photo-excited electrons and holes and facilitate the process of absorbing visible light. This paper contributes to the emergence of multi-functional nanocomposites with possible applications in visible-light driven photocatalysts and makes the Au/ZnO photocatalyst an exceptional choice for practical applications such as environmental purification of organic pollutants in aqueous solution and the synthesis of fine chemicals and intermediates.

  16. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Alberto [Universita di Milano, Italy; Prati, Laura [Universita di Milano, Italy; Su, Dangshen [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  17. Directed flow of antiprotons in Au+Au collisions at AGS

    OpenAIRE

    Barrette, J.; Bellwied, R.; Bennett, S.; Bersch, R.; Braun-Munzinger, P.; Chang, W. C.; Cleland, W. E.; Clemen, M.; Cole, J.; Cormier, T. M.; Dai, Y.; David, G.; Dee, J.; Dietzsch, O.; Drigert, M.

    2000-01-01

    Directed flow of antiprotons is studied in Au+Au collisions at a beam momentum of 11.5A GeV/c. It is shown that antiproton directed flow is anti-correlated to proton flow. The measured transverse momentum dependence of the antiproton flow is compared with predictions of the RQMD event generator.

  18. Stability of gold cages (Au16 and Au17) at finite temperature

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... We have employed ab initio molecular dynamics to investigate the stability of the smallest gold cages, namely Au16 and Au17, at finite temperatures. First, we obtain the ground state structure along with at least 50 distinct isomers for both the clusters. This is followed by the finite temperature simulations of ...

  19. Charged particle density distributions in Au·Au collisions at ...

    Indian Academy of Sciences (India)

    Charged particle pseudorapidity distributions have been measured in Au·Au collisions using the BRAHMS ... Relativistic heavy-ion collisions; charged hadron production; pseudorapidity distribu- tions; centrality .... the predictions of two different theoretical models: (i) the high density gluon saturation model of Kharzeev and ...

  20. Low-temperature solution synthesis of the non-equilibrium ordered intermetallic compounds Au3Fe, Au3Co, and Au3Ni as nanocrystals.

    Science.gov (United States)

    Vasquez, Yolanda; Luo, Zhiping; Schaak, Raymond E

    2008-09-10

    Alloys and intermetallic compounds of Au with the 3d transition metals Fe, Co, and Ni are nonequilibrium phases that have many useful potential applications as catalytic, magnetic, optic, and multifunctional magneto-optic materials. However, the atomically ordered Au-M (M = Fe, Co, Ni) intermetallics are particularly elusive from a synthetic standpoint. Here we report the low-temperature solution synthesis of the L12 (Cu3Au-type) intermetallic compounds Au3Fe, Au3Co, and Au3Ni using n-butyllithium as a reducing agent. Reaction pathway studies for the Au3Co system indicate that Au nucleates first, followed by Co incorporation to form the intermetallic. The nonequilibrium intermetallic nanocrystals have been characterized by powder XRD, TEM, EDS, selected area electron diffraction, and nanobeam electron diffraction, which collectively confirm the compositions and superlattice structures.

  1. Jets and dijets in Au+Au and p+p collisions at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Hardtke, D.; STAR Collaboration

    2002-12-09

    Recent data from RHIC suggest novel nuclear effects in the production of high p{sub T} hadrons. We present results from the STAR detector on high p{sub T} angular correlations in Au+Au and p+p collisions at {radical}S = 200 GeV/c. These two-particle angular correlation measurements verify the presence of a partonic hard scattering and fragmentation component at high p{sub T} in both central and peripheral Au+Au collisions. When triggering on a leading hadron with p{sub T}>4 GeV, we observe a quantitative agreement between the jet cone properties in p+p and all centralities of Au+Au collisions. This quantitative agreement indicates that nearly all hadrons with p{sub T}>4 GeV/c come from jet fragmentation and that jet fragmentation properties are not substantially modified in Au+Au collisions. STAR has also measured the strength of back-to-back high p{sub T} charged hadron correlations, and observes a small suppression of the back-to-back correlation strength in peripheral collisions, and a nearly complete disappearance o f back-to-back correlations in central Au+Au events. These phenomena, together with the observed strong suppression of inclusive yields and large value of elliptic flow at high p{sub T}, are consistent with a model where high p{sub T} hadrons come from partons created near the surface of the collision region, and where partons that originate or propagate towards the center of the collision region are substantially slowed or completely absorbed.

  2. Rapidity density distributions in Au+Au and Au+Ag interactions at 11.6 A GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Nystrand, J.I. [Div. of Cosmic and Subatomic Physis, Lund Univ. (Sweden); Adamovich, M.I.; Aggarwal, M.M.; Alexandrov, Y.A.; Andreeva, N.P.; Anzon, Z.V.; Arora, R.; Avetyan, F.A.; Badyal, S.K.; Basova, E.; Bazarov, I.K.; Bhalla, K.B.; Bhasin, A.; Bhatia, V.S.; Bogdanov, V.G.; Bubnov, V.I.; Burnett, T.H.; Cai, X.; Carshiev, D.A.; Ceitimbetov, A.M.; Chasnikov, I.Y.; Chernova, L.P.; Chernyavsky, M.M.; Eligbaeva, G.Z.; Eremenko, L.E.; Gaitinov, A.S.; Ganssauge, E.R.; Garpman, S.; Gerassimov, S.G.; Graf, C.; Grote, J.; Gulamov, K.G.; Gupta, S.K.; Gupta, V.K.; Jakobsson, B.; Just, L.; Kachroo, S.; Kalyachkina, G.S.; Kanygina, E.K.; Karabova, M.; Kharlamov, S.P.; Kitroo, S.; Krasnov, S.A.; Kumar, V.; Larionova, V.G.; Li, Y.D.; Liu, L.S.; Lokanatan, S.; Lord, J.J.; Lukicheva, N.S.; Luo, S.B.; Maksimkina, T.N.; Mangotra, L.K.; Marutyan, N.A.; Maslennikova, N.V.; Mittra, I.S.; Mookerjee, S.; Musulmanbekov, J.J.; Nasyrov, S.Z.; Navotny, V.S.; Ochs, M.; Orlova, G.I.; Otterlund, I.; Peresadko, N.G.; Petrov, N.V.; Plyushchev, V.A.; Qian, W.Y.; Qin, Y.M.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Roeper, M.; Saidkhanov, N.; Salmanova, N.A.; Sarkisova, L.G.; Sarkisyan, V.R.; Shabratova, G.S.; Shakhova, T.I.; Shpilev, S.N.; Skelding, D.; Soederstrom, K.; Solovjeva, Z.I.; Stenlund, E; Surin, E.L.; Svechnikova, L.N.; Tolstov, K.D.; Tothova, M.; Tretyakova, M.I.; Trofimova, T.P.; Tuleeva, U.; Tursunov, B.P.; Vokal, S.; Vrlakova, J.; Wang, H.Q.; Weng, Z.Q.; Wilkes, R.J.; Xia, Y.L.; Yang, C.B.; Zhang, D.H.; Zheng, P.Y.; Zhokhova, S.I.; Zhou, D.C.; EMU01 Collaboration

    1994-01-03

    Pseudorapidity density distributions of charged particles in heavy-ion collisions have been studied. The results from EMU01 have been compared to the results from the experiments WA80 and E802. The recently obtained pseudorapidity distributions from Au+Au and Au+Ag interactions have been compared to a linear extrapolation from lighter systems. (orig.)

  3. Synthesis and characterization in AuCu–Si nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Novelo, T.E., E-mail: tenovelo@hotmail.com [Centro de Investigación en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnología, Av. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Chihuahua Mexico (Mexico); Amézaga-Madrid, P. [Centro de Investigación en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnología, Av. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Chihuahua Mexico (Mexico); Maldonado, R.D. [Universidad Anáhuac-Mayab, Carretera Mérida-Progreso Km. 15.5 A.P. 96-Cordemex, CP. 97310 Mérida, Yucatán Mexico (Mexico); Oliva, A.I. [Centro de Investigación y de Estudios Avanzados el IPN Unidad Mérida, Departamento de Física Aplicada, Km 6 Antigua Carretera a Progreso, A.P. 73-Cordemex, 97310 Mérida, Yucatán Mexico (Mexico); Alonzo-Medina, G.M. [Universidad Anáhuac-Mayab, Carretera Mérida-Progreso Km. 15.5 A.P. 96-Cordemex, CP. 97310 Mérida, Yucatán Mexico (Mexico)

    2015-03-15

    Au/Cu bilayers with different Au:Cu concentrations (25:75, 50:50 and 75:25 at.%) were deposited on Si(100) substrates by thermal evaporation. The thicknesses of all Au/Cu bilayers were 150 nm. The alloys were prepared by thermal diffusion into a vacuum oven with argon atmosphere at 690 K during 1 h. X-ray diffraction analysis revealed different phases of AuCu and CuSi alloys in the samples after annealing process. CuSi alloys were mainly obtained for 25:75 at.% samples, meanwhile the AuCuII phase dominates for samples prepared with 50:50 at.%. Additionally, the Au:Cu alloys with 75:25 at.%, produce Au{sub 2}Cu{sub 3} and Au{sub 3}Cu phases. The formed alloys were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to study the morphology and the elemental concentration of the formed alloys. - Highlights: • AuCu/Si alloy thin films were prepared by thermal diffusion. • Alloys prepared with 50 at.% of Au produce the AuCuII phase. • Alloys prepared with 75 at.% of Au produce Au{sub 3}Cu and Au{sub 2}Cu{sub 3} phases. • All alloys present diffusion of Si and Cu through the CuSi alloy formation.

  4. Au nanoparticles films used in biological sensing

    Energy Technology Data Exchange (ETDEWEB)

    Rosales Perez, M; Delgado Macuil, R; Rojas Lopez, M; Gayou, V L [Centro de Investigacion en BiotecnologIa Aplicada del IPN, Tepetitla Tlaxcala Mexico C.P. 90700 (Mexico); Sanchez Ramirez, J F, E-mail: mrosalespe@ipn.m [CICATA Legaria Instituto Politecnico Nacional, Mexico Distrito Federal (Mexico)

    2009-05-01

    Lactobacillus para paracasei are used commonly as functional food and probiotic substances. In this work Au nanoparticles self-assembled films were used for Lactobacillus para paracasei determination at five different concentrations. Functionalized substrates were immersed in a colloidal solution for one and a half hour at room temperature and dried at room temperature during four hours. After that, drops of Lactobacillus para paracasei in aqueous solution were put into the Au nanoparticles film and let dry at room temperature for another two hours. Infrared spectroscopy in attenuated total reflectance sampling mode was used to observe generation peaks due to substrate silanization, enhancement of Si-O band intensity due to the Au colloids added to silanized substrate and also to observe the enhancement of Lactobacillus para paracasei infrared intensity of the characteristic frequencies at 1650, 1534 and 1450 cm{sup -1} due to surface enhancement infrared absorption.

  5. PHENIX Results in d + Au Collisions

    Science.gov (United States)

    Chen, Chin-Hao

    2016-04-01

    The PHENIX experiment at the Relativistic Heavy Ion Collider has performed a comprehensive set of measurements in d + Au collisions. Observables in d + Au collisions were originally conceived as a control experiment where no quark-gluon plasma is formed and one could isolate so-called cold nuclear matter effects, including nuclear modified parton distributions and parton multiple scattering. However, recent data from the PHENIX experiment in d + Au, in conjunction with new p + Pb results at the Large Hadron Collider, give strong evidence for a very different picture. We present new results that hint at the formation of a small quark-gluon plasma, that though short lived, leaves a fingerprint of evidence on final state observables. These new results will be discussed in the context of competing theoretical interpretations.

  6. Total structure determination of thiolate-protected Au38 nanoparticles.

    Science.gov (United States)

    Qian, Huifeng; Eckenhoff, William T; Zhu, Yan; Pintauer, Tomislav; Jin, Rongchao

    2010-06-23

    We report the total structure of Au(38)(SC(2)H(4)Ph)(24) nanoparticles determined by single crystal X-ray crystallography. This nanoparticle is based upon a face-fused Au(23) biicosahedral core, which is further capped by three monomeric Au(SR)(2) staples at the waist of the Au(23) rod and six dimeric staples with three on the top icosahedron and other three on the bottom icosahedron. The six Au(2)(SR)(3) staples are arranged in a staggered configuration, and the Au(38)S(24) framework has a C(3) rotation axis.

  7. Au nanorice assemble electrolytically into mesostars.

    Science.gov (United States)

    Bardhan, Rizia; Neumann, Oara; Mirin, Nikolay; Wang, Hui; Halas, Naomi J

    2009-02-24

    Star-shaped mesotructures are formed when an aqueous suspension of Au nanorice particles, which consist of prolate hematite cores and a thin Au shell, is subjected to an electric current. The nanorice particles assemble to form hyperbranched micrometer-scale mesostars. To our knowledge, this is the first reported observation of nanoparticle assembly into larger ordered structures under the influence of an electrochemical process (H(2)O electrolysis). The assembly is accompanied by significant modifications in the morphology, dimensions, chemical composition, crystallographic structure, and optical properties of the constituent nanoparticles.

  8. On the Stark broadening in the Au I and Au II spectra from a helium plasma

    Science.gov (United States)

    Djeniže, S.

    2009-03-01

    The Stark FWHM (Full-Width at Half of the Maximal line intensity, W) of 5 neutral and 26 singly ionized gold (Au I and Au II, respectively) spectral lines have been measured in laboratory helium plasma at approximately 16,600 K electron temperature and 7.4 × 10 22 m - 3 electron density. Five Au I and ten Au II W values are reported for the first time. The Au II W values are compared with recent theoretical data, calculated based on a modified semi-empirical approach, and also with existing experimental W values. Our normalized Stark widths are six times higher than those measured in a laser-produced plasma. Possible explanation of this is recommended here. An agreement (within the accuracy of the experiment and uncertainties of the theoretical approach used) with the recently calculated W data was found in the 6p-7s Au II transition. The calculated hyperfine splitting for the five Au II lines in the 6s-6p transition is also presented. At the stated helium plasma conditions, Stark broadening has been found to be the dominant mechanism in the Au I and Au II line shape formation. A modified version of the linear low-pressure pulsed arc was used as a plasma source operated in helium, with gold atoms as impurities evaporated from the thin gold cylindrical plates located in the homogeneous part of the discharge, providing conditions free of self-absorption. This plasma source ensures good conditions for generation of excited gold ions due to Penning and charge exchange effects.

  9. A novel Au SINE sequence found in a gymnosperm.

    Science.gov (United States)

    Yagi, Eiki; Akita, Toru; Kawahara, Taihachi

    2011-01-01

    Although many SINE families have been identified in the animal kingdom, only a few SINE families have been identified in plants, and their distribution is somewhat limited. The Au SINE (Au) has been found discontinuously in basal angiosperms, monocots, and eudicots. In this study, we examined the presence of the Au in gymnosperms and ferns by PCR using internal primers for Au. As a result, we found Au in a gymnosperm species, Ephedra ciliata. Therefore, Au was supposed to be present in the common ancestor of angiosperms and gymnosperms. The Au in E. ciliate was 15 bp shorter than the consensus sequence, which is similar to the Au SINE found in Glycine. However, the 3'end of the Au found in E. ciliate was more similar to the 3'end of the Medicago-type Au than that of the Glycine-type Au. A phylogenetic tree indicated that the Au sequence from E. ciliate is more closely related to the sequence found in Glycine than that found in Medicago/Lotus. These results indicated that Au were present in both angiosperms and gymnosperms.

  10. Contribution to the study of the biological properties of compounds labeled with radio-chromium {sup 51}Cr; Contribution a l'etude des proprietes biologiques des composes marques au radiochrome {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-07-15

    Among the radioisotopes commonly used in biology and medicine which are controlled Individually in the Radioelement Departement of the Saclay Nuclear Research Centre before being sent to the users, the author has chosen chromium 51 incorporated in inorganic salts or in organic substrates for a study of the biological properties of the compounds. In the first part, he has compared the pathways followed by the radioactive sodium chromate and chromic chloride mixed with blood or given to the whole animal, the object being to determine whether a reduction of hexavalent chromium occurs, both in vitro and in vivo. In the second part, the author has tried to show the validity of using, various substrates labeled with chromium 51, red cells, haemoglobin, plasma proteins and cytochrome c. The results obtained have contributed to underline the interest of using such compounds for biological applications. (author) [French] Parmi les radioisotopes d'utilisation courants en biologie et en medecine qui sont l'objet d'un controle particulier dans le Departement des Radioelements du Centre d'Etudes Nucleaires de Saclay avant leur diffusion aux utilisateurs, l'auteur a choisi le chrome 51 incorpore a des sels mineraux ou a des substrats organiques, afin d'en etudier les proprietes biologiques. Dans la premiere partie, il a compare le sort du chromate de sodium et du chlorure chromique radioactifs melanges a du sang ou administres a l'animal entier en s'efforcant de mettre en evidence une reduction du chrome hexavalent aussi bien in vitro qu'in vivo. Dans la deuxieme partie, il a cherche a etablir la validite de l'emploi de differents substrats marques au chrome 51, l'hematie, l'hemoglobine, les proteines plasmatiques et le cytochrome c. Les resultats obtenus ont permis de souligner le reel interet des applications biologiques des composes marques par le radioisotope. (auteur)

  11. Charged hadron transverse momentum distributions in Au+Au collisions at {radical}S{sub NN} = 200 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Back, B.B.; Baker, M.D.; Barton, D.S.; Betts, R.R.; Ballintijn, M.; Bickley, A.A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M.P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G.A.; Henderson, C.; Hofman, D.J.; Hollis, R.S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C.M.; Lin, W.T.; Manly, S.; McLeod, D.; Michalowski, J.; Mignerey, A.C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I.C.; Pernegger, H.; Reed, C.; Remsberg, L.P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S.G.; Steinberg, P.; Stephans, G.S.F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G.J. van; Verdier, R.; Wadsworth, B.; Wolfs, F.L.H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A.H.; Wyslouch, B

    2003-04-01

    We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at {radical}S{sub NN} = 200 GeV. The evolution of the spectra for transverse momenta p{sub T} from 0.25 to 5 GeV/C is studied as a function of collision centrality. We find a significant change of the spectral shape between proton-antiproton and peripheral Au+Au collisions. When comparing peripheral to central Au+Au collisions, we find that the yields at the highest p{sub T} exhibit approximate scaling with the number of participating nucleons, rather than scaling with the number of binary collisions.

  12. La cardiomyopathie dilatee au centre hospitalier Universitaire ...

    African Journals Online (AJOL)

    La cardiomyopathie dilatee au centre hospitalier Universitaire Tokoin de Lome : A propos de 74 cas hospitalises. ... Le traitement médical a fait appel aux diurétiques (85,1%), aux inhibiteurs de l'enzyme de conversion de l'angiotensine (83,8%) et aux digitaliques (55,4%). Des antiarythmiques, des antiaggrégants ...

  13. Nanoporous Au: an unsupported pure gold catalyst?

    Energy Technology Data Exchange (ETDEWEB)

    Wittstock, A; Neumann, B; Schaefer, A; Dumbuya, K; Kuebel, C; Biener, M; Zielasek, V; Steinrueck, H; Gottfried, M; Biener, J; Hamza, A; B?umer, M

    2008-09-04

    The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nm and specific particle-support interactions have been shown to play important roles. On the contrary, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail taking mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface resulting in surface concentrations of up to 10 at%. Our data suggest that this Ag plays a significant role in activation of molecular oxygen. Therefore, npAu should be considered as a bimetallic catalyst rather than a pure Au catalyst.

  14. Anomalies hematologiques au cours des accidents vasculaires ...

    African Journals Online (AJOL)

    Anomalies hematologiques au cours des accidents vasculaires cerebraux a Abidjan des (Cote d'Ivoire) ... Introduction: En Côte d'Ivoire, les accidents vasculaires cérébraux (AVC) sont de plus en ... The objective of the study was to report the hematological abnormalities in the stroke among black African patients in Abidjan.

  15. Didaktik des außerschulischen Lernens

    CERN Document Server

    Sauerborn, Petra

    2012-01-01

    Kernprobleme schulischer Bildung sind die zunehmenden Verluste an Realitäts- und Praxisbezug sowie die einseitige Betonung der fachwissenschaftlichen Kenntnisse. In jüngster Zeit werden insbesondere moderne didaktisch-methodische Konzepte näher diskutiert und praktiziert. So finden sich etwa die Stichwörter Handlungsorientierter Unterricht und Offener Unterricht in der fachdidaktischen Diskussion wieder. Eine wesentlich aktuellere Form stellt das außerschulische Lernen dar. Ein modernes pädagogisches Verständnis sieht den Unterricht heute nicht mehr als ausschließliche Tätigkeit des Lehrers an, sondern als Aktivität der Lernenden. Außerschulisches Lernen beschreibt die originale Begegnung im Unterricht außerhalb des Klassenzimmers. An außerschulischen Lernorten findet eine unmittelbare AuseinanderSetzung des Lernenden mit seiner räumlichen Umgebung statt. Charakteristisch sind hierbei vor allem die aktive(Mit-)Gestaltung sowie die eigenständige Wahrnehmung mehrperspektivischer Bildungsinhalte d...

  16. Melamine structures on the Au(111) surface

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Castell, Martin R.; Briggs, G. A. D.; Mura, Manuela; Martsinovich, Natalia; Kantorovich, Lev

    2008-01-01

    We report on a joint experimental and theoretical study of the ordered structures of melamine molecules formed on the Au(111)-(22 x root 3) surface. Scanning tunneling microscopy (STM) images taken under UHV conditions reveal two distinct monolayers one of which has never been reported before on

  17. Surface structure of AU3Cu(001)

    DEFF Research Database (Denmark)

    Eckstein, G.A.; Maupai, S.; Dakkouri, A.S.

    1999-01-01

    The surface morphology, composition, and structure of Au3Cu(001) as determined by scanning tunneling microscopy and surface x-ray diffraction are presented. Atomic resolution STM images reveal distinctive geometric features. The analysis of the surface x-ray diffraction data provides clear evidence...... for the surface structure. [S0163-1829(99)04535-X]....

  18. Le CRDI au Pérou

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

    Arequipa. Trujillo. Chiclayo. Piura. Cuzco. Pucallpa. Iquitos. 914. ○ Tumbes. Quelques activités en cours. Voici quelques exemples des travaux de recherche appuyés par le CRDI au Pérou. □ Amélioration des pratiques agricoles pour lutter contre le paludisme. Financement : 500 400 CAD. Période visée : de 2012 à 2016.

  19. Characterization of Au and Bimetallic PtAu Nanoparticles on PDDA-Graphene Sheets as Electrocatalysts for Formic Acid Oxidation

    Science.gov (United States)

    Yung, Tung-Yuan; Liu, Ting-Yu; Huang, Li-Ying; Wang, Kuan-Syun; Tzou, Huei-Ming; Chen, Po-Tuan; Chao, Chi-Yang; Liu, Ling-Kang

    2015-09-01

    Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20-50 and 5-10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°-3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous H2SO4 and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene.

  20. Des institutions au service de villes sûres et inclusives au Venezuela

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

    Caracas, au Venezuela, est l'une des villes les plus violentes au monde; il s'y commet 122 homicides par tranche de 100 000 habitants. Selon les experts en violence urbaine, les inégalités sociales et la disparité des revenus sont étroitement liées à l'ampleur de la violence, mais cette théorie ne tient pas dans le cas ...

  1. Prévention de la violence chez les jeunes au Guatemala, au ...

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

    La violence chez les jeunes, que ceux-ci en soient victimes ou responsables, est l'un des problèmes les plus importants en Amérique centrale. Ce projet de recherche servira à évaluer les stratégies actuelles de prévention de la violence chez les jeunes dans le triangle nord de la région, soit au Salvador, au Guatemala et ...

  2. Directed Flow of Light Nuclei in Au+Au Collisions at AGS Energies

    OpenAIRE

    E877 Collaboration; Barrette, J.; Bellwied, R.; Bennett, S.; Bersch, R.; Braun-Munzinger, P.; Chang, W. C.; Cleland, W. E.; Clemen, M.; Cole, J.; Cormier, T. M.; Dai, Y.; David, G.; Dee, J.; Dietzsch, O.

    1998-01-01

    Directed flow of deuterons, tritons, $^3$He, and $^4$He is studied in Au+Au collisions at a beam momentum of about 10.8 $A$ GeV/c. Flow of all particles is analyzed as a function of transverse momentum for different centralities of the collision. The directed flow signal, $v_1(p_t)$, is found to increase with particle mass. This mass dependence is strongest in the projectile rapidity region.

  3. A first look at Au·Au collisions at RHIC energies using the PHOBOS ...

    Indian Academy of Sciences (India)

    A first look at Au·Au collisions at RHIC energies using the PHOBOS detector. BIRGER BACK1, for the PHOBOS Collaboration. M D Baker2, D S Barton2, R R Betts6, R Bindel7, A Budzanowski3, W Busza4,. A Carroll2, J Corbo2, M P Decowski4, E Garcia6, N George1, K Gulbrandsen4, S Gushue2,. C Halliwell6, J Hamblen8, ...

  4. Flow and bose-einstein correlations in Au-Au collisions at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Manly, Steven; Back, B.B.; Baker, M.D.; Barton, D.S.; Betts, R.R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M.P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hofman, D.; Hollis, R.S.; Holyinski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C.M.; Lin, W.T.; Manly, S.; McLeod, D.; Michalowski, J.; Mignerey, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I.C.; Pernegger, H.; Reed, C.; Remsberg, L.P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S.G.; Steinberg, P.; Stephans, G.S.F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G.J. van; Verdier, R.; Wadsworth, B.; Wolfs, F.L.H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A.H.; Wyslouch, B

    2003-03-10

    Argonne flow and Bose-Einstein correlations have been measured in Au-Au collisions at {radical}S{sub NN} = 130 and 200 GeV using the PHOBOS detector at RHIC. The systematic dependencies of the flow signal on the transverse momentum, pseudorapidity, and centrality of the collision, as well as the beam energy are shown. In addition, results of a 3-dimensional analysis of two-pion correlations in the 200 GeV data are presented.

  5. Femmes, migration et droits au Mali et au Sénégal | CRDI - Centre ...

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

    En Afrique de l'Ouest, notamment au Mali et au Sénégal, les migrations féminines concernent majoritairement les flux d'une part à l'intérieur des pays et d'autre part entre les pays. Du fait de la pauvreté, manque d'opportunités économiques et manque d'éducation, les jeunes filles migrantes risquent de subir des violations ...

  6. A reagentless amperometric immunosensor based on nano-au and ...

    African Journals Online (AJOL)

    In this paper, carboxyl-ferrocene (Fc-COOH) was explored to label alphafetoprotein antibody (anti-AFP), which was then mixed with AU nanoparticles (nano-Au) and multi-walled carbon nanotubes (MWCNTs) dispersed by chitosan (CS) to form the nano-Au/MWCNTs/anti-AFP-Fc chitosan composite. After that, the composite ...

  7. Au pair på ulige vilkår

    DEFF Research Database (Denmark)

    Christiansen, Connie Carøe

    2008-01-01

    Antallet af au pairs i Danmark fra Fillipinerne er steget markant i de seneste år. Mens danske myndigheder betragter au pair-ordningen som kulturudveksling blandt unge mennesker, ser fillipinske au pairs derimod den som en mulighed for at tjene penge så de kan forsørge deres egen familie i Fillip...

  8. The point-defect of carbon nanotubes anchoring Au nanoparticles

    DEFF Research Database (Denmark)

    Lv, Y. A.; Cui, Y. H.; Li, X. N.

    2010-01-01

    between Au clusters and CNTs by means of density functional theory calculations. Both experimental and theoretical studies show that point defects are the anchoring sites of Au nanoparticles. The mechanisms of enhanced bond between Au and CNTs via the point defects are explained by the analysis of density...

  9. Common suppression pattern of η and π0 mesons at high transverse momentum in Au+Au collisions at VsNN=200 GeV

    NARCIS (Netherlands)

    Peitzmann, T.

    2006-01-01

    Inclusive transverse momentum spectra of η mesons have been measured within pT=2–10 GeV/c at midrapidity by the PHENIX experiment in Au+Au collisions at VsNN=200 GeV. In central Au+Au the η yields are significantly suppressed compared to peripheral Au+Au, d+Au, and p+p yields scaled by the

  10. Electronic and geometric structures of Au30 clusters: a network of 2e-superatom Au cores protected by tridentate protecting motifs with u3-S.

    Science.gov (United States)

    Tian, Zhimei; Cheng, Longjiu

    2016-01-14

    Density functional theory calculations have been performed to study the experimentally synthesized Au30S(SR)18 and two related Au30(SR)18 and Au30S2(SR)18 clusters. The patterns of thiolate ligands on the gold cores for the three thiolate-protected Au30 nanoclusters are on the basis of the "divide and protect" concept. A novel extended protecting motif with u3-S, S(Au2(SR)2)2AuSR, is discovered, which is termed the tridentate protecting motif. The Au cores of Au30S(SR)18, Au30(SR)18 and Au30S2(SR)18 clusters are Au17, Au20 and Au14, respectively. The superatom-network (SAN) model and the superatom complex (SAC) model are used to explain the chemical bonding patterns, which are verified by chemical bonding analysis based on the adaptive natural density partitioning (AdNDP) method and aromatic analysis on the basis of the nucleus-independent chemical shift (NICS) method. The Au17 core of the Au30S(SR)18 cluster can be viewed as a SAN of one Au6 superatom and four Au4 superatoms. The shape of the Au6 core is identical to that revealed in the recently synthesized Au18(SR)14 cluster. The Au20 core of the Au30(SR)18 cluster can be viewed as a SAN of two Au6 superatoms and four Au4 superatoms. The Au14 core of Au30S2(SR)18 can be regarded as a SAN of two pairs of two vertex-sharing Au4 superatoms. Meanwhile, the Au14 core is an 8e-superatom with 1S(2)1P(6) configuration. Our work may aid understanding and give new insights into the chemical synthesis of thiolate-protected Au clusters.

  11. The effect of Au amount on size uniformity of self-assembled Au nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S-H; Wang, D-C; Chen, G-Y; Chen, K-Y [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Taiwan (China)

    2008-03-15

    The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl{sub 4}{sup -} and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl{sub 4}{sup -} and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl{sub 4}{sup -} and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

  12. Effects of Excimer Irradiation Treatment on Thermocompression Au-Au Bonding

    Science.gov (United States)

    Naoko Unami,; Katsuyuki Sakuma,; Jun Mizuno,; Shuichi Shoji,

    2010-06-01

    We studied the feasibility of using vacuum ultraviolet (VUV) treatment as a surface improvement technique with Au-Au flip-chip bonding. For fine-pitch electrical interconnections in three-dimensional (3D) stack applications, robust and reliable bonding is desirable; in this case, surface modification treatment is needed before the bonding process. A VUV surface treatment was used to remove organic contaminants. Samples of electroplated Au pads were examined by X-ray photoelectron spectroscopy (XPS) to evaluate the chemical composition of the Au surfaces. The XPS results revealed that the carbon-based contaminants on the surface were removed by the VUV treatment. The shear strength of the bonded sample was also improved. The average shear strength of a bump with VUV treatment is 1.6 times larger than that of a bump without VUV treatment. Cross-sectional scanning electron microscopy (SEM) images of the bonded samples confirmed the absence of voids and cracks. The results show that VUV treatment has clear effects on Au-Au flip-chip bonding.

  13. Results from the PHOBOS Experiment on Au+Au Collisions at RHIC

    CERN Document Server

    Wozniak, K; Baker, M D; Barton, D S; Basilev, S N; Baum, R; Betts, R R; Bialas, A; Bindel, R; Bogucki, W; Budzanowski, A; Busza, W; Carroll, A; Ceglia, M; Chang, Y H; Chen, A E; Coghen, T; Conner, C L; Czyz, W; Dabrowski, B; Decowski, M P; Despet, M; Fita, P; Fitch, J; Friedl, M; Galuszka, K; Ganz, R E; García-Solis, E; George, N; Godlewski, J; Gomes, C; Griesmayer, E; Gulbrandsen, K H; Gushue, S; Halik, J; Halliwell, C; Haridas, P; Hayes, A; Heintzelman, G A; Henderson, C; Hollis, R; Holynski, R; Holzman, B; Johnson, E; Kane, J; Katzy, J M; Kita, W; Kotula, J; Kraner, H W; Kucewicz, W; Kulinich, P A; Law, C; Lemler, M A; Ligocki, T J; Lin, W T; Manly, S L; McLeod, D; Michalowski, J; Mignerey, A C; Mülmenstädt, J; Neal, M; Nouicer, R; Olszewski, A; Pak, R; Park, I C; Patel, M; Pernegger, H; Plesko, M; Reed, C; Remsberg, L P; Reuter, M; Roland, C; Roland, G; Ross, D; Rosenberg, L J; Ryan, J; Sanzgiri, A; Sarin, P; Sawicki, P; Scaduto, J; Shea, J; Sinacore, J; Skulski, W; Steadman, S G; Stephans, G S F; Steinberg, P; Straczek, A; Stodulski, M; Strek, M; Stopa, Z; Sukhanov, A; Surowiecka, K; Tang, J L; Teng, R; Trzupek, A; Vale, C J; van Nieuwenhuizen, G J; Verdier, R; Wadsworth, B; Wolfs, F L H; Wosiek, B; Wozniak, K; Wuosmaa, A H; Wyslouch, B; Zalewski, Kasper

    2001-01-01

    PHOBOS is one of four experiments studying the Au-Au interactions at RHIC. The data collected during the first few weeks after the RHIC start-up, using the initial configuration of the PHOBOS detector, were sufficient to obtain the first physics results for the most central collisions of Au nuclei at the center of mass energy of 56 and 130 AGeV. The pseudorapidity density of charged particles near midrapidity is shown and compared with data at lower energies and from $pp$ and $p\\bar{p}$ collisions. The progress of the analysis of the data is also presented.PHOBOS is one of four experiments studying the Au-Au interactions at RHIC. The data collected during the first few weeks after the RHIC start-up, using the initial configuration of the PHOBOS detector, were sufficient to obtain the first physics results for the most central collisions of Au nuclei at the center of mass energy of 56 and 130 AGeV. The pseudorapidity density of charged particles near midrapidity is shown and compared with data at lower energie...

  14. Au(I/Au(III-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

    Directory of Open Access Journals (Sweden)

    Deyun Qian

    2011-06-01

    Full Text Available A straightforward, efficient, and reliable redox catalyst system for the Au(I/Au(III-catalyzed Sonogashira cross-coupling reaction of functionalized terminal alkynes with arylboronic acids under mild conditions has been developed.

  15. From the Ternary Eu(Au/In)2 and EuAu4(Au/In)2 with Remarkable Au/In Distributions to a New Structure Type: The Gold-Rich Eu5Au16(Au/In)6 Structure.

    Science.gov (United States)

    Steinberg, Simon; Card, Nathan; Mudring, Anja-Verena

    2015-09-08

    The ternary Eu(Au/In)2 (EuAu(0.46)In(1.54(2))) (I), EuAu4(Au/In)2 (EuAu(4+x)In(2-x) with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2-"EuAu4In2". The site preferences of the disordered Au/In positions in II were investigated for different hypothetical "EuAu4(Au/In)2" models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au-In contacts. A chemical bonding analysis on two "EuAu5In" and "EuAu4In2" models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.

  16. In-situ STM study of phosphate adsorption on Cu(111), Au(111) and Cu/Au(111) electrodes

    DEFF Research Database (Denmark)

    Schlaup, Christian; Horch, Sebastian

    2013-01-01

    The interaction of Cu(111), Au(111) and Cu-covered Au(111) electrodes with a neutral phosphate buffer solution has been studied by means of cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). Under low potential conditions, both the Cu(111) and the Au(111) ...

  17. Tuning the kondo effect in thin Au films by depositing a thin layer of Au on molecular spin-dopants

    NARCIS (Netherlands)

    Ataç, Derya; Gang, T.; Yilmaz, M.D.; Bose, Saurabh; Lenferink, Aufrid T.M.; Otto, Cornelis; de Jong, Machiel Pieter; Huskens, Jurriaan; van der Wiel, Wilfred Gerard

    2013-01-01

    We report on the tuning of the Kondo effect in thin Au films containing a monolayer of cobalt(II) terpyridine complexes by altering the ligand structure around the Co2+ ions by depositing a thin Au capping layer on top of the monolayer on Au by magnetron sputtering (more energetic) and e-beam

  18. Probing the quenching of CdSe/ZnS qdots by Au, Au/Ag, and Au/Pd nanoparticles.

    Science.gov (United States)

    Han, Hyunjoo; Valle, Valerie; Maye, Mathew M

    2012-11-02

    The resonance energy transfer between CdSe/ZnS quantum dots (qdots) and three metallic nanoparticles (NPs) with different surface plasmon resonance (SPR) characteristics were studied. Gold, gold/silver and gold/palladium NPs were used as energy acceptors for qdots with donor emission at 570 nm. Due to the different spectral overlaps between the SPR signatures and qdot emission, varied energy transfer characteristics were observed. The energy transfer was quantified via the Stern-Volmer relationship, since in this study the energy transfer was collision based. The Au/Ag and Au/Pd NPs in particular showed high K(SV) values, while the Au NPs showed much lower energy transfer efficiency. Since the NPs used in this study were relatively large (d ~ 15-20 nm), the experimental system was also influenced by the NP extinction coefficients of ≈10(8) M(-1) cm(-1). To address this potential inner filter effect, the quenching profiles were normalized by SPR transmittance. The results are important to the field, as many of these classes of nanomaterials are being employed in energy transfer based studies, as well as in colorimetric sensing.

  19. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L. [AGH University of Science and Technology, Cracow 30-059 (Poland); Adkins, J.K. [University of Kentucky, Lexington, KY, 40506-0055 (United States); Agakishiev, G. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Aggarwal, M.M. [Panjab University, Chandigarh 160014 (India); Ahammed, Z. [Variable Energy Cyclotron Centre, Kolkata 700064 (India); Alekseev, I. [Alikhanov Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Aparin, A. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Arkhipkin, D.; Aschenauer, E.C. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Averichev, G.S. [Joint Institute for Nuclear Research, Dubna, 141 980 (Russian Federation); Bai, X. [University of Illinois at Chicago, Chicago, IL 60607 (United States); Bairathi, V. [National Institute of Science Education and Research, Bhubaneswar 751005 (India); Banerjee, A. [Variable Energy Cyclotron Centre, Kolkata 700064 (India); Bellwied, R. [University of Houston, Houston, TX 77204 (United States); Bhasin, A. [University of Jammu, Jammu 180001 (India); Bhati, A.K. [Panjab University, Chandigarh 160014 (India); Bhattarai, P. [University of Texas, Austin, TX 78712 (United States); Bielcik, J. [Czech Technical University in Prague, FNSPE, Prague, 115 19 (Czech Republic); Bielcikova, J. [Nuclear Physics Institute AS CR, 250 68 Řež/Prague (Czech Republic); Bland, L.C. [Brookhaven National Laboratory, Upton, NY 11973 (United States); and others

    2015-12-17

    The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au + Au and minimum-bias d + Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  20. Di-hadron correlations with identified leading hadrons in 200 GeV Au+Au and d+Au collisions at STAR

    Directory of Open Access Journals (Sweden)

    L. Adamczyk

    2015-12-01

    Full Text Available The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au+Au and minimum-bias d+Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au+Au data with respect to the d+Au reference and the absence of such an enhancement for leading non-pions (protons and kaons are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  1. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L; Adkins, JK; Agakishiev, G; Aggarwal, MM; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, EC; Averichev, GS; Bai, X; Bairathi, V; Banerjee, A; Bellwied, R; Bhasin, A; Bhati, AK; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, LC; Bordyuzhin, IG; Bouchet, J; Brandenburg, D; Brandin, AV; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, JM; Cebra, D; Cervantes, MC; Chakaberia, I; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, X; Chen, JH; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, HJ; Das, S; De Silva, LC; Debbe, RR; Dedovich, TG; Deng, J; Derevschikov, AA; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, JL; Draper, JE; Du, CM; Dunkelberger, LE; Dunlop, JC; Efimov, LG; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, CE; Fulek, L; Gagliardi, CA; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, DS; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A; Hamed, A; Haque, R; Harris, JW; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, GW; Hofman, DJ; Horvat, S; Huang, T; Huang, B; Huang, HZ; Huang, X; Huck, P

    2015-10-23

    The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au + Au and minimum-bias d + Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  2. THE VALENCE OF AU IN AUTE2 AND AUSE STUDIED BY X-RAY-ABSORPTION SPECTROSCOPY

    NARCIS (Netherlands)

    ETTEMA, ARHF; STEGINK, TA; HAAS, C

    The gold compounds AuTe2 and AuSe contain Au atoms in two different chemical surroundings. In the literature these different coordinations have been associated with a difference in valency of the Au atoms. In this paper the occupation of the 5d shell in AuSe and AuTe2 is deduced from a study of the

  3. Thermal desorption of Au from W(001) surface

    CERN Document Server

    Blaszczyszyn, R; Godowski, P J

    2002-01-01

    Adsorption of Au on W(001) at 450 K up to multilayer structures was investigated. Temperature programmed desorption technique was used in determination of coverage dependent desorption energy (region up to one monolayer). Results were discussed in terms of competitive interactions of Au-Au and Au-W atoms. Simple procedure for prediction of faceting behavior on the interface, basing on the desorption data, was postulated. It was deduced that the Au/W(001) interface should not show faceting tendency after thermal treatment. (author)

  4. [Hyp-Au-Sn9(Hyp)3-Au-Sn9(Hyp)3-Au-Hyp]-: the longest intermetalloid chain compound of tin.

    Science.gov (United States)

    Binder, Mareike; Schrenk, Claudio; Block, Theresa; Pöttgen, Rainer; Schnepf, Andreas

    2017-10-12

    The reaction of the metalloid tin cluster [Sn10(Hyp)4]2- with (Ph3P)Au-SHyp (Hyp = Si(SiMe3)3) gave an intermetalloid cluster [Au3Sn18(Hyp)8]-1, which is the longest intermetalloid chain compound of tin to date. 1 shows a structural resemblance to binary AuSn phases, which is expected for intermetalloid clusters.

  5. Photoswitchable Faraday effect in EuS-Au nanosystems

    Energy Technology Data Exchange (ETDEWEB)

    Kawashima, Akira; Nakanishi, Takayuki; Kitagawa, Yuichi; Fushimi, Koji; Hasegawa, Yasuchika [Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, North-13 West-8, Kita-ku, 060-8628, Sapporo (Japan)

    2016-01-15

    Effective photoswitchable europium sulfide nanocrystals with gold nanoparticles using dithiol (DDT: 1,10-decanedithiol) joint molecules, EuS-Au nanosystems, are demonstrated. The TEM image indicates the formation of EuS-Au nanosystems composed of cube-shaped EuS nanocrystals and spherical Au nanoparticles. Under visible-light irradiation, a drastic change of absorption band of EuS-Au nanosystems at around 600 nm was observed. The Faraday effects of EuS-Au nanosystems were estimated using magnetic circular dichroism (MCD) measurements. The effective change of the MCD spectra of EuS-Au nanosystems under visible-light irradiation was successfully observed at around 670 nm for the first time. The effective reversible changes in MCD spectra with the alternative irradiation cycles of visible light (>440 nm) and dark are also presented. The decrease rate of rotation angle at 670 nm of EuS-Au nanosystems is larger than that of absorbance. These results indicate that the effective change of MCD spectra of EuS-Au nanosystems would be dominated not only by a drastic change of absorption band related to enhanced LSPR of Au nanoparticles but also by specific interaction between EuS and Au in nanosystem under irradiation. Illustration of photoswitch and TEM image of EuS-Au nanosystems. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Introduction au numéro

    Directory of Open Access Journals (Sweden)

    Diane-Gabrielle Tremblay

    2005-07-01

    Full Text Available Depuis quelques années, le thème de l’économie sociale fait couler beaucoup d’encre au Québec, comme ailleurs. Ce numéro présente un bilan de l’économie sociale au Québec, coordonné par Jean-Marc Fontan et Denis Bussières. Toutefois, afin d’avoir un portrait plus global et une perspective théorique sur la question, Interventions économiques a sollicité un texte de Jacques Defourny, afin de compléter le dossier. En effet, l’économie sociale, les secteurs non-marchands, les services de proximi...

  7. Le fonds Gabriel Tarde au CHEVS

    OpenAIRE

    Louise Salmon

    2016-01-01

    Le fonds d’archives « Gabriel Tarde » déposé au CHEVS nous permet de mieux saisir l’érudit autodidacte que fut Gabriel Tarde. De la genèse de sa pensée à ses réseaux de sociabilité, de l’homme de sciences à l’homme de lettres, ses archives témoignent à la fois des usages et des enjeux des ressources archivistiques en histoire, mais elles permettent surtout un renouvellement du regard sur Gabriel Tarde en l’inscrivant au cœur de son temps que fut la fin du XIXème siècle.At the CHEVS in Paris, ...

  8. Identification of sup 186 Au. alpha. activity

    Energy Technology Data Exchange (ETDEWEB)

    Akovali, Y.A.; Toth, K.S. (Oak Ridge National Laboratory, Oak Ridge, TN (USA)); Bingham, C.R. (University of Tennessee, Knoxville, TN (USA) Oak Ridge National Laboratory, Oak Ridge, TN (USA)); Kassim, M.B.; Zhang, M. (University of Tennessee, Knoxville, TN (USA)); Carter, H.K. (UNISOR, Oak Ridge Associated Universities, Oak Ridge, TN (USA)); Hamilton, W.D. (Joint Institute for Heavy Ion Research, Holifield Heavy Ion Research Facility, Oak Ridge, TN (USA) Vanderbilt University, Nashville, TN (USA)); Kormicki, J. (Vanderbilt University, Nashville, TN (USA))

    1990-09-01

    With the use of an on-line isotope separator, the {alpha} activity of {sup 186}Au was identified for the first time. Only one {alpha} group ({ital E}{sub {alpha}}=4653{plus minus}15 keV) was observed. This transition was found not to be in coincidence with {gamma} rays so that it probably proceeds either to the {sup 182}Ir ground state or to a low-lying level whose deexciting {gamma} rays could not be detected. The {alpha}-decay branching was determined to be (8{plus minus}2){times}10{sup {minus}4}% from which a hindrance factor of 1.9{plus minus}0.9 was deduced. The 4653-keV {alpha} transition must therefore connect the 3{sup {minus}} {sup 186}Au ground state with a {sup 182}Ir level with the same spin and configuration.

  9. Au Based Nanocomposites Towards Plasmonic Applications

    Science.gov (United States)

    Panniello, A.; Curri, M. L.; Placido, T.; Reboud, V.; Kehagias, N.; Sotomayor Torres, C. M.; Mecerreyes, D.; Agostiano, A.; Striccoli, M.

    2010-06-01

    Incorporation of nano-sized metals in polymers can transfer their unique features to the host matrix, providing nanocomposite materials with improved optical, electric, magnetic and mechanical properties. In this work, colloidal Au nanorods have been incorporated into PMMA based random co-polymer, properly functionalized with amino groups and the optical and morphological properties of the resulting nanocomposite have been investigated by spectroscopic and AFM measurements. Au nanorods have demonstrated to preserve the plasmon absorption and to retain morphological features upon the incorporation, thus making the final metal modified polymer composite exploitable for the fabrication of plasmonic devices. The prepared nanocomposites have been then patterned by Nano Imprint Lithography technique in order to demonstrate the viability of the materials towards optical applications.

  10. Near-infrared-responsive, superparamagnetic Au@Co nanochains

    Directory of Open Access Journals (Sweden)

    Varadee Vittur

    2017-08-01

    Full Text Available This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains with optical extinctions in the near infrared (NIR. The Au@Co nanochains were synthesized via a one-pot galvanic replacement route involving a redox-transmetalation process in aqueous medium, where Au salt was reduced to form Au shells on Co seed templates, affording hollow Au@Co nanochains. The Au shells serve not only as a protective coating for the Co nanochain cores, but also to give rise to the optical properties of these unique nanostructures. Importantly, these bifunctional, magneto-optical Au@Co nanochains combine the advantages of nanophotonics (extinction at ca. 900 nm and nanomagnetism (superparamagnetism and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field.

  11. Tuning the collective switching behavior of azobenzene/Au hybrid materials: flexible versus rigid azobenzene backbones and Au(111) surfaces versus curved Au nanoparticles.

    Science.gov (United States)

    Liu, Chunyan; Zheng, Dong; Hu, Weigang; Zhu, Qiang; Tian, Ziqi; Zhao, Jun; Zhu, Yan; Ma, Jing

    2017-11-09

    The combination of photo-responsive azobenzene (AB) and biocompatible Au nanomaterials possesses potential applications in diverse fields such as biosensing and thermotherapy. To explore the influence of azobenzene moieties and Au substrates on the collective switching behavior, two different azobenzene derivatives (rigid biphenyl-controlled versus flexible alkoxyl chain-linked) and three different Au substrates (a planar Au(111) surface, curved Au 102 (SR) 44 and Au 25 (SR) 18 clusters) were chosen to form six Au@AB combinations. A reactive molecular dynamics (RMD) model considering both the torsion and inversion path was implemented to simulate the collective photo-induced cis-to-trans switching process of AB monolayers on Au substrates. The major driving force for isomerization is demonstrated to be the torsion of the C-N[double bond, length as m-dash]N-C dihedral angle, in addition to the minor contribution from an inversion pathway. The isomerization process can be divided into the preliminary conformation switching stage and the later relaxation stage, in which a gradual self-organization is observed for 40 ps. The Au substrate affects the packing structure of the AB monolayer, while the choice of different kinds of ABs tunes the intermolecular interaction in the monolayer. Flexible alkoxyl-linked F-AB may achieve much faster conversion on Au clusters than on the surface. For rigid biphenyl-based R-AB anchored on Au nanoparticles (AuNPs), a competitive torsion between the biphenyl and C-N[double bond, length as m-dash]N-C dihedral may delay the C-N[double bond, length as m-dash]N-C dihedral torsion and the following isomerization process. After the R-AB molecules were anchored on the Au(111) surface, the strong π-π stacking between biphenyl units accelerates the collective isomerization process. A curvature-dependent effect is observed for R-AB SAMs on different-sized substrates. The cooperation between functional AB monolayers and the Au substrate

  12. Les entreprises au Royaume-Uni

    OpenAIRE

    Appay, Beatrice

    1987-01-01

    This chapter of the book "Formations et emplois qualifiés. Les transformations dans le Bâtiment en France et au Royaume-Uni" analyses management strategies and organisational changes during a period of continuous crisis. The concept of cascading subcontracting (sous-traitance en cascade) introduced here encapsulates a new phenomenon observed simultaneously in the ever changing organisation of work between and within the firms. This is an important result of a research based on a 34 firm monog...

  13. la lutte contre le SIDA au Cameroun

    African Journals Online (AJOL)

    Chantel

    plurielles'). Tsala Tsala, J.-Ph. (2001). Medicina tradicional y sistema de salud publica en Camerun. Siso/Saude. 35: 48 -57. UNICEF, ONUSIDA, OMS (2001). Suivi et évaluation (au niveau local) de la prévention intégrée de la transmission mère-enfant du VIH dans les pays à revenus faibles.(doc ined. Projet 03/2001). 156.

  14. Le CRDI au Népal

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

    et visant à évaluer et à faire connaître les innovations en matière de production agricole, de transformation et de mise en marché. Le CRDI collabore avec le Fonds international de développement agricole à la mise sur pied de ce réseau, dont les membres sont reliés au moyen de technologies numériques. TE. K. G. U. R.

  15. Interstellar Pickup Ion Observations to 38 au

    Science.gov (United States)

    McComas, D. J.; Zirnstein, E. J.; Bzowski, M.; Elliott, H. A.; Randol, B.; Schwadron, N. A.; Sokół, J. M.; Szalay, J. R.; Olkin, C.; Spencer, J.; Stern, A.; Weaver, H.

    2017-11-01

    We provide the first direct observations of interstellar H+ and He+ pickup ions in the solar wind from 22 to 38 au. We use the Vasyliunas and Siscoe model functional form to quantify the pickup ion distributions, and while the fit parameters generally lie outside their physically expected ranges, this form allows fits that quantify variations in the pickup H+ properties with distance. By ∼20 au, the pickup ions already provide the dominant internal pressure in the solar wind. We determine the radial trends and extrapolate them to the termination shock at ∼90 au, where the pickup H+ to core solar wind density reaches ∼0.14. The pickup H+ temperature and thermal pressure increase from 22 to 38 au, indicating additional heating of the pickup ions. This produces very large extrapolated ratios of pickup H+ to solar wind temperature and pressure, and an extrapolated ratio of the pickup ion pressure to the solar wind dynamic pressure at the termination shock of ∼0.16. Such a large ratio has profound implications for moderating the termination shock and the overall outer heliospheric interaction. We also identify suprathermal tails in the H+ spectra and complex features in the He+ spectra, likely indicating variations in the pickup ion history and processing. Finally, we discover enhancements in both H+ and He+ populations just below their cutoff energies, which may be associated with enhanced local pickup. This study serves to document the release and serves as a citable reference of these pickup ion data for broad community use and analysis.

  16. Functionalized Au@Ag-Au nanoparticles as an optical and SERS dual probe for lateral flow sensing.

    Science.gov (United States)

    Bai, Tingting; Wang, Meng; Cao, Min; Zhang, Juan; Zhang, Kangzhen; Zhou, Ping; Liu, Zhengxia; Liu, Ying; Guo, Zhirui; Lu, Xiang

    2018-02-14

    Lateral flow assay strips (LFASs) with Au nanoparticles (NPs) have been widely used as a probe for biomarkers in point-of-care testing; however, there still remain challenges in detection sensitivity and quantitative analysis. In this study, we developed a surface-enhanced Raman scattering (SERS)-based LFAS for quantitative analysis of a biomarker in the low concentration range. Moreover, apart from conventional Au NPs, three other types of citrate-capped Au-Ag bimetallic NPs: Au core with Ag shell NPs (Au@Ag NPs), rattle-like Au core in Ag-Au shell NPs (Au@Ag-Au NPs) and Ag-Au NPs were prepared and functionalized, and their solution-based SERS activities were comprehensively studied by experimental measurement and theoretical analysis. The results clearly indicated that the citrate-capped Au@Ag-Au NPs exhibited the highest SERS activity among the probes tested. Au@Ag-Au NPs were used as both optical and SERS probes in a SERS-based LFAS. In the presence of the analyte at high concentrations, a purple color appeared in the test zone. Highly sensitive and quantitative analysis was realized by measurement of SERS signals from the test lines. One of the most specific markers for cardiac injury, cardiac troponin I (cTnI), was chosen as the detection model. The detection limit of the SERS-based LFAS for cardiac troponin I was 0.09 ng/mL, lowered by nearly 50 times compared with visual results, and could be further lowered by optimization. These results demonstrated that the SERS-based LFAS using citrate-capped Au@Ag-Au NPs as probes can be a powerful tool for highly sensitive and quantitative detection of biomarkers. Graphical abstract A surface-enhanced Raman scattering (SERS)-based lateral flow assay strip using rattle-like Au core in Ag-Au shell (Au@Ag-Au) nanoparticles as probes was developed for quantitative analysis of a biomarker, with a detection limit nearly 50 times lower than that of visual assessment. C control line, T test line.

  17. A photoresponsive Au25 nanocluster protected by azobenzene derivative thiolates

    Science.gov (United States)

    Negishi, Yuichi; Kamimura, Ukyo; Ide, Mao; Hirayama, Michiyo

    2012-06-01

    An Au25 cluster protected by azobenzene derivative thiolates (S-Az) ([Au25(S-Az)18]-) was synthesized with the aim of producing a photoresponsive Au25 cluster. The matrix-assisted laser desorption/ionization mass spectrum of the product revealed that [Au25(S-Az)18]- was synthesized in high purity. Optical absorption spectra of [Au25(S-Az)18]- obtained before and after photoirradiation suggest that the azobenzenes in the ligands of Au25(S-Az)18 isomerize with an efficiency of nearly 100%, both from the trans to cis conformation and from the cis to trans conformation. Furthermore, the redox potential and optical absorption of Au25(S-Az)18 were found to change reversibly due to photoisomerization of azobenzenes.An Au25 cluster protected by azobenzene derivative thiolates (S-Az) ([Au25(S-Az)18]-) was synthesized with the aim of producing a photoresponsive Au25 cluster. The matrix-assisted laser desorption/ionization mass spectrum of the product revealed that [Au25(S-Az)18]- was synthesized in high purity. Optical absorption spectra of [Au25(S-Az)18]- obtained before and after photoirradiation suggest that the azobenzenes in the ligands of Au25(S-Az)18 isomerize with an efficiency of nearly 100%, both from the trans to cis conformation and from the cis to trans conformation. Furthermore, the redox potential and optical absorption of Au25(S-Az)18 were found to change reversibly due to photoisomerization of azobenzenes. Electronic supplementary information (ESI) available: Details of the experimental procedure and characterization of the products. See DOI: 10.1039/c2nr30830d

  18. Photocatalysis enhancement of Au/BFO nanoparticles using plasmon resonance of Au NPs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Cai, Zhongyang; Ma, Xueming, E-mail: xmma@phy.ecnu.edu.cn

    2015-12-15

    BiFeO{sub 3} (BFO) nanoparticles was synthesized via sol–gel technique, and successfully loaded with small sizes of gold nanoparticles (Au NPs) by impregnation-reduction method to extremely enhance the BFO photocatalytic activity. The obviously stronger optical absorption of Au/BFO observed from the UV–vis diffuse reflectance spectrum confirmed that the surface plasmon resonance (SPR) effect occured on the surface of Au NPs. And the surface plasmon-induced localized electric field could allow the formation of electron/hole pairs in the near surface region of BFO which can migrate to the surface without undergoing electron/hole (e{sup −}/h{sup +}) pair recombination. The more electrons and holes formed, the more ·OH will be generated to decompose the CR solution. When the gold loading in Au/BFO nanoparticles is 3.36 wt%, the obtained Au/BFO catalyst exhibits best photocatalytic activity evaluated by photocatalysis degradation of Congo red (CR) solution under the visible light irradiation.

  19. Virus-templated Au and Au/Pt Core/shell Nanowires and Their Electrocatalytic Activitives for Fuel Cell Applications

    Science.gov (United States)

    LEE, YOUJIN; KIM, JUNHYUNG; YUN, DONG SOO; NAM, YOON SUNG; SHAO-HORN, YANG; BELCHER, ANGELA M.

    2014-01-01

    A facile synthetic route was developed to make Au nanowires (NWs) from surfactant-mediated bio-mineralization of a genetically engineered M13 phage with specific Au binding peptides. From the selective interaction between Au binding M13 phage and Au ions in aqueous solution, Au NWs with uniform diameter were synthesized at room temperature with yields greater than 98 % without the need for size selection. The diameters of Au NWs were controlled from 10 nm to 50 nm. The Au NWs were found to be active for electrocatalytic oxidation of CO molecules for all sizes, where the activity was highly dependent on the surface facets of Au NWs. This low-temperature high yield method of preparing Au NWs was further extended to the synthesis of Au/Pt core/shell NWs with controlled coverage of Pt shell layers. Electro-catalytic studies of ethanol oxidation with different Pt loading showed enhanced activity relative to a commercial supported Pt catalyst, indicative of the dual functionality of Pt for the ethanol oxidation and Au for the anti-poisoning component of Pt. These new one-dimensional noble metal NWs with controlled compositions could facilitate the design of new alloy materials with tunable properties. PMID:24910712

  20. Au 38 (SPh) 24 : Au 38 Protected with Aromatic Thiolate Ligands

    Energy Technology Data Exchange (ETDEWEB)

    Rambukwella, Milan; Burrage, Shayna; Neubrander, Marie; Baseggio, Oscar; Aprà, Edoardo; Stener, Mauro; Fortunelli, Alessandro; Dass, Amala

    2017-03-21

    Au38(SR)24 is one of the most extensively investigated gold nanomolecules along with Au25(SR)18 and Au144(SR)60. However, so far it has only been prepared using aliphatic-like ligands, where R = –SC6H13, -SC12H25 and –SCH2CH2Ph. Au38(SCH2CH2Ph)24 when reacted with HSPh undergoes core-size conversion to Au36(SPh)24, and existing literature suggest that Au38(SPh)24 cannot be synthesized. Here, contrary to prevailing knowledge, we demonstrate that Au38(SPh)24 can be prepared if the ligand exchanged conditions are optimized, without any formation of Au36(SPh)24. Conclusive evidence is presented in the form of MALDI-MS, ESI-MS characterization, and optical spectra of Au38(SPh)24 in a solid glass form showing distinct differences from that of Au38(S-aliphatic)24. Theoretical analysis confirms experimental assignment of the optical spectrum and shows that the stability of Au38(SPh)24 is comparable to that of its aliphatic analogues, but results from different physical origins, with a significant component of ligand-ligand attractive interactions.

  1. Au99(SPh)42 nanomolecules: aromatic thiolate ligand induced conversion of Au144(SCH2CH2Ph)60.

    Science.gov (United States)

    Nimmala, Praneeth Reddy; Dass, Amala

    2014-12-10

    A new aromatic thiolate protected gold nanomolecule Au99(SPh)42 has been synthesized by reacting the highly stable Au144(SCH2CH2Ph)60 with thiophenol, HSPh. The ubiquitous Au144(SR)60 is known for its high stability even at elevated temperature and in the presence of excess thiol. This report demonstrates for the first time the reactivity of the Au144(SCH2CH2Ph)60 with thiophenol to form a different 99-Au atom species. The resulting Au99(SPh)42 compound, however, is unreactive and highly stable in the presence of excess aromatic thiol. The molecular formula of the title compound is determined by high resolution electrospray mass spectrometry (ESI-MS) and confirmed by the preparation of the 99-atom nanomolecule using two ligands, namely, Au99(SPh)42 and Au99(SPh-OMe)42. This mass spectrometry study is an unprecedented advance in nanoparticle reaction monitoring, in studying the 144-atom to 99-atom size evolution at such high m/z (∼12k) and resolution. The optical and electrochemical properties of Au99(SPh)42 are reported. Other substituents on the phenyl group, HS-Ph-X, where X = -F, -CH3, -OCH3, also show the Au144 to Au99 core size conversion, suggesting minimal electronic effects for these substituents. Control experiments were conducted by reacting Au144(SCH2CH2Ph)60 with HS-(CH2)n-Ph (where n = 1 and 2), bulky ligands like adamantanethiol and cyclohexanethiol. It was observed that conversion of Au144 to Au99 occurs only when the phenyl group is directly attached to the thiol, suggesting that the formation of a 99-atom species is largely influenced by aromaticity of the ligand and less so on the bulkiness of the ligand.

  2. Charge transport through O-deficient Au-MgO-Au junctions

    KAUST Repository

    Fadlallah, M. M.

    2009-12-29

    Metal-oxide heterostructures have been attracting considerable attention in recent years due to various technological applications. We present results of electronic structure and transport calculations for the Au-MgO-Au (metal-insulator-metal) heterostructure based on density-functional theory and the nonequilibrium Green’s functions method. The dependence of the conductance of the heterostructure on the thickness of the MgO interlayer and the interface spacing is studied. In addition, we address the effects of O vacancies. We observe deviations from an exponentially suppressed conductance with growing interlayer thickness caused by Au-O chemical bonds. Electronic states tracing back to O vacancies can increase the conductance. Furthermore, this effect can be enhanced by enlarging the interface spacing as the vacancy induced Mg states are shifted toward the Fermi energy.

  3. Elliptic flow in Au+Au collisions at $\\sqrt{S_{NN}}$=130 GeV

    CERN Document Server

    Ackermann, K H; Adler, C; Ahammed, Z; Ahmad, S; Allgower, C; Amsbaugh, J; Anderson, M; Anderssen, E; Arnesen, H; Arnold, L; Averichev, G S; Baldwin, A R; Balewski, J T; Barannikova, O Yu; Barnby, L S; Baudot, J; Beddo, M E; Bekele, S; Belaga, V V; Bellwied, R; Bennett, S; Bercovitz, J; Berger, J; Betts, W; Bichsel, H; Bieser, F; Bland, L C; Bloomer, M A; Blyth, C O; Böhm, J; Bonner, B E; Bonnet, D; Bossingham, R R; Botlo, M; Boucham, A; Bouillo, N; Bouvier, S; Bradley, K; Brady, F P; Braithwaite, E S; Braithwaite, W; Brandin, A B; Brown, R L; Brugalette, G; Byrd, C; Caines, H; Calderón de la Barca-Sanchez, M; Cardenas, A; Carr, L; Carroll, J; Castillo, J; Caylor, B; Cebra, D; Chathopadhyay, S; Chen, M L; Chen, W; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Chrin, J; Christie, W; Coffin, J P; Conin, L; Consiglio, C; Cormier, T M; Cramer, J G; Crawford, H J; Danilov, V I; Dayton, D; De Mello, M; Deng, W S; Derevshchikov, A A; Dialinas, M; Díaz, H; De Young, P A; Didenko, L; Dimassimo, D; Dioguardi, J; Dominik, Wojciech; Drancourt, C; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Edwards, W R; Efimov, L G; Eggert, T; Emelyanov, V I; Engelage, J; Eppley, G; Erazmus, B; Etkin, A; Fachini, P; Feliciano, C; Ferenc, D; Ferguson, M I; Fessler, H; Finch, E; Fine, V; Fisyak, Yu; Flierl, D; Flores, I; Foley, Kenneth J; Fritz, D; Gagunashvili, N D; Gans, J; Gazdzicki, M; Germain, M; Geurts, F J M; Ghazikhanian, V; Gojak, C; Grabski, J; Grachov, O A; Grau, M; Greiner, D E; Greiner, L; Grigoriev, V; Grosnick, D P; Gross, J; Guilloux, G; Gushin, E M; Hall, J; Hallman, T J; Hardtke, D; Harper, G; Harris, J W; He, P; Heffner, M; Heppelmann, S; Herston, T; Hill, D; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Howe, M; Huang, H Z; Humanic, T J; Hümmler, H; Hunt, W; Hunter, J; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Jacobson, S; Jared, R; Jensen, P; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kenney, V P; Khodinov, A; Klay, J L; Klein, S R; Klyachko, A A; Koehler, G; Konstantinov, A S; Kormilitsyne, V; Kotchenda, L; Kotov, I V; Kovalenko, A D; Krämer, M; Kravtsov, P; Krüger, K; Krupien, T; Kuczewski, P; Kühn, C E; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T J; Leonhardt, W; Leontiev, V M; Leszczynski, P; Le Vine, M J; Li, Q; Li, Z; Liaw, C J; Lin, J; Lindenbaum, S J; Lindenstruth, V; Lindstrom, P J; Lisa, M A; Liu, H; Ljubicic, T; Llope, W J; Lo Curto, G; Long, H; Longacre, R S; López-Noriega, M; Lopiano, D; Love, W A; Lutz, Jean Robert; Lynn, D; Madansky, L; Maier, R S; Majka, R; Maliszewski, A; Margetis, S; Marks, K; Marstaller, R; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; Matyushevsky, E A; McParland, C P; McShane, T S; Meier, J; Melnik, Yu M; Meshchanin, A P; Middlekamp, P; Mikhalin, N; Miller, B; Milosevich, Z; Minaev, N G; Minor, B; Mitchell, J; Mogavero, E; Moiseenko, V A; Moltz, D M; Moore, C F; Morozov, V; Morse, R; De Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Ngo, T; Nguyen, M; Nguyen, T; Nikitin, V A; Nogach, L V; Noggle, T; Norman, B; Nurushev, S B; Nussbaum, T; Nystrand, J; Odyniec, Grazyna Janina; Ogawa, A; Ogilvie, C A; Olchanski, K; Oldenburg, M; Olson, D; Ososkov, G A; Ott, G; Padrazo, D; Paic, G; Pandey, S U; Panebratsev, Yu A; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Pentia, M; Perevozchikov, V; Peryt, W; Petrov, V; Pinganaud, W; Pirogov, S; Platner, E D; Pluta, J; Polk, I; Porile, N T; Porter, J; Poskanzer, A M; Potrebenikova, E V; Prindle, D J; Pruneau, C A; Puskar-Pasewicz, J; Rai, G; Rasson, J E; Ravel, O; Ray, R L; Razin, S V; Reichhold, D M; Reid, J; Renfordt, R E; Retière, F; Ridiger, A; Riso, J; Ritter, H G; Roberts, J B; Röhrich, D; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V L; Sakrejda, I; Sánchez, R; Sandler, Z; Sandweiss, J; Sappenfield, P; Saulys, A C; Savin, I A; Schambach, J; Scharenberg, R P; Scheblien, J; Scheetz, R; Schlüter, R; Schmitz, N; Schröder, L S; Schulz, M; Schüttauf, A; Sedlmeir, J; Seger, J E; Seliverstov, D M; Seyboth, J; Seyboth, P; Seymour, R; Shakaliev, E I; Shestermanov, K E; Shi, Y; Shimansky, S S; Shuman, D B; Shvetcov, V S; Skoro, G P; Smirnov, N; Smykov, L P; Snellings, R; Solberg, K; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, Reinhard; Stolpovsky, A; Stone, N; Stone, R; Strikhanov, M N; Stringfellow, B C; Ströbele, H; Struck, C; Suaide, A A P; Sugarbaker, E R; Suire, C; Symons, T J M; Takahashi, J; Tang, A H; Tarchini, A; Tarzian, J; Thomas, J H; Tikhomirov, V; Szanto de Toledo, A; Tonse, S R; Trainor, T; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V N; Tsai, O; Turner, K; Ullrich, T S; Underwood, D G; Vakula, I; Van Buren, G; Van der Molen, A; Vanyashin, A V; Vasilevskii, I M; Vasilev, A N; Vigdor, S E; Visser, G; Voloshin, S A; Vu, C; Wang, F; Ward, H; Weerasundara, D D; Weidenbach, R; Wells, R; Wenaus, T J; Westfall, G D; Whitfield, J P; Whitten, C; Wieman, H H; Willson, R; Wilson, K; Wirth, J; Wisdom, J; Wissink, S W; Witt, R; Wolf, J; Wood, L; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevsky, Yu V; Zhang, J; Zhang, W M; Zhu, J; Zimmerman, D; Zoulkarneev, R; Zubarev, A N

    2001-01-01

    Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at sqrt(s_NN)=130 GeV using the STAR TPC at RHIC. The elliptic flow signal, v_2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

  4. D and $^{3}He$ production in $\\sqrt{s}$ = 130 GeV Au + Au collisions

    CERN Document Server

    Adler, C; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J T; Barannikova, O Yu; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A B; Cadman, R V; Caines, H; Calderón de la Barca-Sanchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Cormier, T M; Cramer, J G; Crawford, H J; De Mello, M; Deng, W S; Derevshchikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Finch, E; Fisyak, Yu; Flierl, D; Foley, Kenneth J; Fu, J; Gagunashvili, N D; Gans, J; Gaudichet, L; Germain, M; Geurts, F J M; Ghazikhanian, V; Grabski, J; Grachov, O A; Greiner, D E; Grigoriev, V; Guedon, M; Guschin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J L; Klein, S R; Klyachko, A A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Krämer, M; Kravtsov, P; Krüger, K; Kuhn, C; Kulikov, A V; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T J; Lednicky, R; Leontiev, V M; Le Vine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; Lo Curto, G; Long, H; Longacre, R S; López-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnik, Yu M; Meshchanin, A P; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; De Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, Grazyna Janina; Ogawa, A; Okorokov, V; Oldenburg, M; Oson, D; Paic, G; Pandey, S U; Panebratsev, Yu A; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevozchikov, V; Peryt, W; Petrov, V A; Platner, E D; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E V; Prindle, D J; Pruneau, C A; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D M; Reid, J G; Retière, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V L; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schröder, L S; Schüttauf, A; Schweda, K; Seger, J E; Seliverstov, D M; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimansky, S S; Shvetcov, V S; Skoro, G P; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, Reinhard; Stolpovsky, A; Strikhanov, M N; Stringfellow, B C; Struck, C; Suaide, A A P; Sugarbaker, E R; Suire, C; Sumbera, M; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Tikhomirov, V; Trainor, T A; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T S; Underwood, D G; Van Buren, G; Van der Molen, A; Vanyashin, A V; Vasilevski, I M; Vasilev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T J; Westfall, G D; Whitten, C; Wieman, H H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevsky, Yu V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N; 10.1103/PhysRevLett.87.262301

    2001-01-01

    The first measurements of light antinucleus production in Au + Au collisions at the Relativistic Heavy-Ion Collider are reported. The observed production rates for d and /sup 3/He are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at CERN SPS energy. These analyses also indicate that the 3He freeze-out volume is smaller than the d freeze-out volume. (22 refs).

  5. Nuclear Stopping in Central Au+Au Collisions at RHIC Energies

    Directory of Open Access Journals (Sweden)

    Ying Yuan

    2014-01-01

    Full Text Available Nuclear stopping in central Au+Au collisions at relativistic heavy-ion collider (RHIC energies is studied in the framework of a cascade mode and the modified ultrarelativistic quantum molecular dynamics (UrQMD transport model. In the modified mode, the mean field potentials of both formed and “preformed” hadrons (from string fragmentation are considered. It is found that the nuclear stopping is increasingly influenced by the mean-field potentials in the projectile and target regions with the increase of the reaction energy. In the central region, the calculations of the cascade model considering the modifying factor can describe the experimental data of the PHOBOS collaboration.

  6. Coût des soins de santé attribuables au tabagisme au Cambodge ...

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

    Au Cambodge, l'incidence de la tuberculose et du tabagisme est élevée de sorte que le coût du tabagisme comprendra aussi le coût des décès " supplémentaires " occasionnés par la tuberculose liée au tabagisme. Dans ce pays, les systèmes d'information sur la santé ne sont ni rigoureux, ni fiables. Par conséquent, on ne ...

  7. Relativistic multireference many-body perturbation theory calculations on Au64+ - Au69+ ions

    Energy Technology Data Exchange (ETDEWEB)

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2006-03-31

    Many-body perturbation theory (MBPT) calculations are an adequate tool for the description of the structure of highly charged multi-electron ions and for the analysis of their spectra. They demonstrate this by way of a re-investigation of n=3, {Delta}n=0 transitions in the EUV spectra of Na-, Mg-, Al-like, and Si-like ions of Au that have been obtained previously by heavy-ion accelerator based beam-foil spectroscopy. They discuss the evidence and propose several revisions on the basis of the multi-reference many-body perturbation theory calculations of Ne- through P-like ions of Au.

  8. Measurements of direct photons in Au+Au collisions with PHENIX

    CERN Document Server

    Bannier, Benjamin

    2014-01-01

    The PHENIX experiment has published direct photon yields and elliptic flow coefficients $v_2$ from Au+Au collisions at RHIC energies. These results have sparked much theoretical discussion. The measured yields and flow parameters are difficult to reconcile in current model calculations of thermal radiation based on hydrodynamic time evolution of the collision volume. Our latest analyses which use high statistics data from the 2007 and 2010 runs allow the determination of direct photon yields with finer granularity in centrality and photon momentum and down to $p_T$ as low as 0.4 GeV/$c$. We will summarize the current status and present new results from PHENIX.

  9. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    Science.gov (United States)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  10. Conductive Au nanowires regulated by silk fibroin nanofibers

    Science.gov (United States)

    Dong, Bo-Ju; Lu, Qiang

    2014-03-01

    Conductive Au-biopolymer composites have promising applications in tissue engineering such as nerve tissue regeneration. In this study, silk fibroin nanofibers were formed in aqueous solution by regulating silk self-assembly process and then used as template for Au nanowire fabrication. We performed the synthesis of Au seeds by repeating the seeding cycles for several times in order to increase the density of Au seeds on the nanofibers. After electroless plating, densely decorated Au seeds grew into irregularly shaped particles following silk nanofiber to fill the gaps between particles and finally form uniform continuous nanowires. The conductive property of the Au-silk fibroin nanowires was studied with current-voltage ( I-V) measurement. A typical ohmic behavior was observed, which highlighted their potential applications in nerve tissue regeneration.

  11. Lateral spreading of Au contacts on InP

    Science.gov (United States)

    Fatemi, Navid S.; Weizer, Victor G.

    1990-01-01

    The contact spreading phenomenon observed when small area Au contacts on InP are annealed at temperatures above about 400 C was investigated. It was found that the rapid lateral expansion of the contact metallization which consumes large quantities of InP during growth is closely related to the third stage in the series of solid state reactions that occur between InP and Au, i.e., to the Au3In-to-Au9In4 transition. Detailed descriptions are presented of both the spreading process and the Au3In-to-Au9In4 transition along with arguments that the two processes are manifestations of the same basic phenomenon.

  12. Que faisons-nous au CERN ?

    CERN Multimedia

    1999-01-01

    Le CERN a pour vocation la science pure, l'étude des questions les plus fondamentales de la nature:Qu'est-ce que la matière ?D'ou vient-elle ? Comment s'agglomère-t-elle en formes complexes comme les étoiles, les planètes et les êtres humains ? Au CERN, les collisions de particules servent à sonder le coeur de la matière et les chercheurs du Laboratoire étudient ces millions de collisions de particules afin de trouver des réponses à ces questions.

  13. Caroline Datchary, La Dispersion au travail

    Directory of Open Access Journals (Sweden)

    Guillaume Lecoeur

    2012-12-01

    Full Text Available Impression de ne pas pouvoir faire totalement son travail, insatisfaction, Trouble Musculo- Squelettique, mais aussi sentiment d’efficacité, d’excitation et parfois de plénitude. Ces sensations, bien qu’ambivalentes, ont néanmoins un point commun selon Caroline Datchary : elles sont engendrées par des situations de « dispersion au travail ». Mutation du travail oblige, les toujours Nouvelles Technologies de l’Information et de la Communication (NTIC ont fait leur apparition, la pression conc...

  14. Quantum interference effects in nanostructured Au

    Science.gov (United States)

    Pratumpong, P.; Cochrane, R. F.; Evans, S. D.; Johnson, S.; Howson, M. A.

    2002-11-01

    We present results on the magnetoresistance and temperature dependence of the resistivity for nanostructured Au produced by chemical means. The magnetoresistance was typical of highly disordered metals exhibiting quantum interference effects. We fitted the data and were able to determine the spin-orbit scattering relaxation time to be 10-12 s and we found the inelastic scattering time at 10 K to be 10-11 s. The inelastic scattering rate varied as T3 between 4 and 20 K, which is typical for electron-phonon scattering in disordered metals.

  15. Quantum interference effects in nanostructured Au

    CERN Document Server

    Pratumpong, P; Evans, S D; Johnson, S; Howson, M A

    2002-01-01

    We present results on the magnetoresistance and temperature dependence of the resistivity for nanostructured Au produced by chemical means. The magnetoresistance was typical of highly disordered metals exhibiting quantum interference effects. We fitted the data and were able to determine the spin-orbit scattering relaxation time to be 10 sup - sup 1 sup 2 s and we found the inelastic scattering time at 10 K to be 10 sup - sup 1 sup 1 s. The inelastic scattering rate varied as T sup 3 between 4 and 20 K, which is typical for electron-phonon scattering in disordered metals.

  16. Quantum interference effects in nanostructured Au

    Energy Technology Data Exchange (ETDEWEB)

    Pratumpong, P [Department of Materials, University of Leeds, Leeds LS2 9JT (United Kingdom); Cochrane, R F [Department of Materials, University of Leeds, Leeds LS2 9JT (United Kingdom); Evans, S D [Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Johnson, S [Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Howson, M A [Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2002-11-18

    We present results on the magnetoresistance and temperature dependence of the resistivity for nanostructured Au produced by chemical means. The magnetoresistance was typical of highly disordered metals exhibiting quantum interference effects. We fitted the data and were able to determine the spin-orbit scattering relaxation time to be 10{sup -12} s and we found the inelastic scattering time at 10 K to be 10{sup -11} s. The inelastic scattering rate varied as T{sup 3} between 4 and 20 K, which is typical for electron-phonon scattering in disordered metals.

  17. Phase behavior of Au and Pt surfaces

    DEFF Research Database (Denmark)

    Grübel, G.; Gibbs, D.; Zehner, D.M.

    1993-01-01

    We summarize the results of X-ray scattering studies of the Au(001) and Pt(001) surfaces between 300 K and their respective bulk melting temperatures (T(m)). Both surfaces exhibit three distinct structural phases. At high temperatures (0.88T(m) surfaces are disordered. The Pt(001......) surface is rough. At a temperature of T/T(m) almost-equal-to 0.88 there are reversible phase transformations to incommensurate, corrugated-hexagonal phases. Below T/T(m) almost-equal-to 0.8 hexagonal domains rotate with respect to the substrate orientation. In Pt, the rotational transformation...

  18. Caracterisation Du Regime Alimentaire Des Personnes Agees Au ...

    African Journals Online (AJOL)

    L'étude s'est déroulée dans la ville de Cotonou au cours de la période transitionnelle entre la soudure et l'abondance alimentaire (octobre-novembre), avec 225 hommes et femmes ayant au moins 60 ans, apparemment en bonne santé mentale, sélectionnés au hasard par la méthode d'échantillonnage en grappes à 3 ...

  19. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    Directory of Open Access Journals (Sweden)

    Nisha Shabnam

    Full Text Available In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant and Spinacia oleracea (a terrestrial plant turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles.

  20. principales écologies rizicoles au Burkina Faso

    African Journals Online (AJOL)

    Un inventaire des nématodes parasites du riz au Burkina Faso a été réalisé au cours de la campagne agricole humide 2016-2017. Ce travail de recherche vise à étudier la prévalence et l'abondance des principaux nématodes parasites associés au riz dans les 3 principales écologies rizicoles que sont la riziculture pluviale ...

  1. Complications liees a la fibroscopie bronchique au CHU Sylvanus ...

    African Journals Online (AJOL)

    Durant une période allant de 1er février 2012 au 31 janvier 2013, les données portant sur les incidents ou accidents survenus au cours de la fibroscopie bronchique (au cours de la prémédication, pendant l'examen et les 7 jours suivants) ont étés collectées chez les patients ayant subi une fibroscopie bronchique dans le ...

  2. Acteurs et strategies face aux nouveaux defis securitaires au Benin ...

    African Journals Online (AJOL)

    De même, de nouveaux acteurs dont la communauté des chasseurs au centre et au nord du Bénin, les adeptes du ''Zangbéto'' au sud, les ONG et autres sont nés avec leurs stratégies. Mots clés: acteurs, stratégies, sécurité, développement. English Abstract. Although the security constitute the essential condition for all ...

  3. Plasmonic welding of hybrid Au-ZnO nanostructure

    Science.gov (United States)

    Chen, Z. Y.; Yang, H. B.; Ghosh, P.; Li, Q.; Qiu, M.

    2017-06-01

    We report that 532 nm CW laser can be used to obtain non-wetting metal-semiconductor (Au-ZnO) Schottky heterojunctions by plasmonic welding. Single crystal Au and n-type ZnO nanowires are placed on gold (Au) and titanium (Ti) electrodes, respectively, and the junction welding is realized. The current-voltage (I-V) characteristic curve of the single Schottky rectifier is also measured.

  4. Resistance aux antibiotiques des bacteries isolees en 2009 au ...

    African Journals Online (AJOL)

    Objectif : Contribuer à la surveillance de la résistance bactérienne aux antibiotiques au Togo en étudiant la résistance aux antibiotiques des bactéries. Méthode Il s'agit d'une étude descriptive transversale portant sur les comptes rendus des antibiogrammes réalisés du 1er janvier au 31 décembre 2009 au Laboratoire de ...

  5. Conjugated electrical properties of Au nanoparticle–polyaniline network

    Science.gov (United States)

    Usami, Yuki; Otsuka, Yoichi; Naitoh, Yasuhisa; Matsumoto, Takuya

    2017-12-01

    We investigated the electrical properties of a two-dimensional (2D) network consisting of multiple Au nanoparticles (AuNPs) and self-doped polyaniline sulfonate (SPAN). Nonlinear current–voltage (I–V) characteristics with wide variations were observed in the networks. The temperature dependence of the I–V characteristics exhibited a short localization length, suggesting conjugated electronic properties of the AuNP–SPAN network. This result provides a new direction for network-based molecular electronic devices.

  6. Measurement of the dielectron continuum in p+p and Au+Au collisions at RHIC

    CERN Document Server

    Dahms, Torsten

    2010-01-01

    PHENIX has measured the e^+e^- pair continuum in sqrt(s_NN) = 200 GeV Au+Au and p+p collisions over a wide range of mass and transverse momenta. While the p+p data in the mass range below the phi meson are well described by known contributions from light meson decays, the Au+Au minimum bias inclusive mass spectrum shows an enhancement by a factor of 4.7 +/- 0.4(stat)} +/- 1.5(syst) +/- 0.9(model) in the mass range 0.15

  7. Experimental evidence for electron localization on Au upon photo-activation of Au/anatase catalysts

    NARCIS (Netherlands)

    Carneiro, J.T.; Carneiro, Joana T.; Savenije, Tom J.; Mul, Guido

    2009-01-01

    Time resolved microwave conductivity (TRMC) measurements show that the presence of Au on anatase Hombikat UV100 significantly reduces the lifetime of mobile electrons formed by photo-excitation of this photocatalyst at 300 nm, providing evidence for the widely acclaimed electron localization effect

  8. تهیه و ارزیابی غشاهای شبکه آمیخته پلی وینیل کلراید-نانوذرات اکسیدروی به منظور جداسازی CO2 /N2 ،ا CO2/CH4 و N2/CH4

    Directory of Open Access Journals (Sweden)

    2013-12-01

    Full Text Available در این پژوهش غشاهای شبکه آمیخته پلی وینیل کلراید- نانوذرات اکسیدروی تهیه شده و به منظور بررسی خواص جداسازی گاز، مورد ارزیابی قرار گرفتند. اثر افزایش اکسید روی و نیز فشار خوراک بر عملکرد جداسازی گاز این غشاها برای گازهای هلیم، نیتروژن، متان و دی اکسید کربن مورد بررسی قرار گرفت. نتایج به دست آمده نشان می‏دهد که تراوایی همه گازها با افزایش نانوذرات اکسیدروی روند افزایشی داشته است. تراوایی گازهای هلیم، متان، دی اکسید کربن و نیتروژن در غشاهای شبکه آمیخته حاوی 15% وزنی اکسید روی در فشار bar 8، به ترتیب از 56/3، 007/0، 21/0 و 01/0 به 9/49، 12، 4/26 و 6/1 نسبت به غشاهای بدون نانو ذرات افزایش یافته است. همچنین، تراوایی هر یک از گازهای مورد مطالعه با افزایش فشار خوراک ورودی، افزایش یافته و انتخاب پذیری جفت‏های گازی مذکور با افزایش فشار، روند ‌کاهشی را دنبال کرده است. نتایج آزمون مقاومت مکانیکی نشان می‏دهد که استفاده از نانوذرات اکسید روی در ساختار غشا توانسته است مدول کششی را به میزان 11% بهبود دهد.

  9. Preparations for p-Au run in 2015

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-12-31

    The p-Au particle collision is a unique category of collision runs. This is resulted from the different charge mass ratio of the proton and fully stripped Au ion (1 vs.79/197). The p-Au run requires a special acceleration ramp, and movement of a number of beam components as required by the beam trajectories. The DX magnets will be moved for the first time in the history of RHIC. In this note, the planning and preparations for p-Au run will be presented.

  10. Divided café-au-lait macule of the mouth.

    Science.gov (United States)

    Sergay, Amanda; Silverberg, Nanette B

    2007-05-01

    We describe a 4-year-old, otherwise healthy boy with a congenital history of a perioral and labial segmental café-au-lait macule, who was noted to have unilateral localized gingival hyperpigmentation that aligned with the café-au-lait macule. This case is highly illustrative of the embryologic timing of the genetic event locally, which leads to café-au-lait type hyperpigmentation. Because the facial features and the ectoderm overlying the facial muscles develop around the third to fourth week of gestation, the distribution of this café-au-lait macule suggests development at the same time.

  11. The self assembly of thymine at Au(110)/liquid interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Molina Contreras, J.R. [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Mexico (Mexico); Smith, C.I.; Bowfield, A.; Weightman, P. [Physics Department, University of Liverpool (United Kingdom); Tillner, F. [Fachbereich Physik, Universitaet Konstanz (Germany)

    2012-06-15

    We show that thymine self-assembles into an ordered structure when adsorbed at a Au(110)/liquid interface. Reflection anisotropy spectroscopy (RAS) shows that as found for cytosine and adenine the adsorbed thymine molecules are oriented essentially vertically on the Au(110) surface with the molecule aligned along one of the principal axes of the Au(110) surface. Simulations of the RA spectra to an empirical model indicates that as found for adsorbed cytosine and adenine, thymine is aligned along the [1 anti 10] direction on the Au(110) surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Design of Au/SPIO composite nanoparticle for facile and biocompatible surface functionalization via Au-S bond

    Energy Technology Data Exchange (ETDEWEB)

    Seino, Satoshi, E-mail: seino@mit.eng.osaka-u.ac.jp; Shibata, Yujin; Yamanaka, Masayuki; Nakagawa, Takashi [Osaka University, Graduate School of Engineering (Japan); Mukai, Yohei; Nakagawa, Shinsaku [Osaka University, Graduate School of Pharmaceutical Sciences and Center for Advanced Medical Engineering and Informatics (Japan); Yamamoto, Takao A. [Osaka University, Graduate School of Engineering (Japan)

    2013-01-15

    Immobilization of Au nanoparticles on super-paramagnetic iron-oxide (SPIO) enables facile and biocompatible surface functionalization via Au-S bond. Au/SPIO composite nanoparticle is easily modified by thiol-modified polyethylene glycol (PEG-SH), and they are successfully applied on MR tumor imaging. However, its large hydrodynamic size ({approx}150 nm) still causes the accumulation to liver in vivo. In this study, we controlled the hydrodynamic size of Au/SPIO by testing different raw SPIOs and stabilizing polymers. As the best candidate, Au/Molday-ION which was synthesized from Molday-ION and polyvinyl alcohol comprised the hydrodynamic size of 56 nm. Moreover, PEGylated Au/Molday-ION showed excellent dispersibility in blood serum, with the hydrodynamic size of 65 nm. This surface functionalization strategy is effective for the constructions of magnetic nanocarriers for in vivo applications.

  13. Approche historiographique des pratiques sportives au Cameroun

    Directory of Open Access Journals (Sweden)

    Biwole M. Claude Emmanuel Abolo

    2016-01-01

    En 50 ans d'indépendance, le sport camerounais a beaucoup évolué. De 11 en 1970, les fédérations sportives sont passées à plus de 40 aujourd'hui et les titres, trophées et médailles ne se comptent plus depuis lors. Le Cameroun est devenu progressivement une nation où le sport compte et où l'exploit sportif n'est plus méprisé, rejeté, voire vilipendé. Hier assimilés à des brutes épaisses, les sportifs sont aujourd'hui admirés et adulés. Finie l'image négative de marginaux qui leur collait au corps : finis les sous-entendus ridicules où ils étaient classés au bas de l'échelle sociale, juste bons pour bander les muscles et réaliser des performances. C'est cela la plus grande victoire du sport camerounais en 50 ans d'existence. Il a réussi à faire l'unanimité et les performances des sportifs devenues pour toute la nation un modèle, une référence et un réel motif de fierté.

  14. IMAGING PROMINENCE ERUPTIONS OUT TO 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Brian E.; Howard, Russell A.; Linton, Mark G., E-mail: brian.wood@nrl.navy.mil [Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)

    2016-01-10

    Views of two bright prominence eruptions trackable all the way to 1 AU are here presented, using the heliospheric imagers on the Solar TErrestrial RElations Observatory (STEREO) spacecraft. The two events first erupted from the Sun on 2011 June 7 and 2012 August 31, respectively. Only these two examples of clear prominence eruptions observable this far from the Sun could be found in the STEREO image database, emphasizing the rarity of prominence eruptions this persistently bright. For the 2011 June event, a time-dependent 3D reconstruction of the prominence structure is made using point-by-point triangulation. This is not possible for the August event due to a poor viewing geometry. Unlike the coronal mass ejection (CME) that accompanies it, the 2011 June prominence exhibits little deceleration from the Sun to 1 AU, as a consequence moving upwards within the CME. This demonstrates that prominences are not necessarily tied to the CME's magnetic structure far from the Sun. A mathematical framework is developed for describing the degree of self-similarity for the prominence's expansion away from the Sun. This analysis suggests only modest deviations from self-similar expansion, but close to the Sun the prominence expands radially somewhat more rapidly than self-similarity would predict.

  15. Apprentissage administratif : L'apprentissage au CERN

    CERN Multimedia

    2004-01-01

    APPRENTISSAGE ADMINISTRATIF FORMATION ET DEVELOPPEMENT HR/PMD/RCC L'APPRENTISSAGE AU CERN pour les professions d'employé(e) de commerce et d'assistant(e) en information documentaire L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 1 place est offerte pour la formation d'employé(e) de commerce 2 places sont offertes pour la formation d'assistant(e) en information documentaire L'apprentissage dure 3 ans. Minima requis pour faire acte de candidature : • avoir terminé la scolarité obligatoire • être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne,Finlande, France, Grèce, Hongrie, Italie, Norvège...

  16. Mesomorphic Lamella Rolling of Au in Vacuum

    Directory of Open Access Journals (Sweden)

    Chen Shuei-Yuan

    2009-01-01

    Full Text Available Abstract Lamellar nanocondensates in partial epitaxy with larger-sized multiply twinned particles (MTPs or alternatively in the form of multiple-walled tubes (MWTs having nothing to do with MTP were produced by the very energetic pulse laser ablation of Au target in vacuum under specified power density and pulses. Transmission electron microscopic observations revealed (111-motif diffraction and low-angle scattering. They correspond to layer interspacing (0.241–0.192 nm and the nearest neighbor distance (ca. 0.74–0.55 nm of atom clusters within the layer, respectively, for the lamella, which shows interspacing contraction with decreasing particle size under the influence of surface stress and rolls up upon electron irradiation. The uncapped MWT has nearly concentric amorphous layers interspaced by 0.458–0.335 nm depending on dislocation distribution and becomes spherical onions for surface-area reduction upon electron dosage. Analogous to graphene-derived tubular materials, the lamella-derived MWT of Au could have pentagon–hexagon pair at its zig-zag junction and useful optoelectronic properties worthy of exploration.

  17. Hollow Au@Pd and Au@Pt core-shell nanoparticles as electrocatalysts for ethanol oxidation reactions

    KAUST Repository

    Song, Hyon Min

    2012-09-27

    Hybrid alloys among gold, palladium and platinum become a new category of catalysts primarily due to their enhanced catalytic effects. Enhancement means not only their effectiveness, but also their uniqueness as catalysts for the reactions that individual metals may not catalyze. Here, preparation of hollow Au@Pd and Au@Pt core-shell nanoparticles (NPs) and their use as electrocatalysts are reported. Galvanic displacement with Ag NPs is used to obtain hollow NPs, and higher reduction potential of Au compared to Ag, Pd, and Pt helps to produce hollow Au cores first, followed by Pd or Pt shell growth. Continuous and highly crystalline shell growth was observed in Au@Pd core-shell NPs, but the sporadic and porous-like structure was observed in Au@Pt core-shell NPs. Along with hollow core-shell NPs, hollow porous Pt and hollow Au NPs are also prepared from Ag seed NPs. Twin boundaries which are typically observed in large size (>20 nm) Au NPs were not observed in hollow Au NPs. This absence is believed to be due to the role of the hollows, which significantly reduce the strain energy of edges where the two lattice planes meet. In ethanol oxidation reactions in alkaline medium, hollow Au@Pd core-shell NPs show highest current density in forward scan. Hollow Au@Pt core-shell NPs maintain better catalytic activities than metallic Pt, which is thought to be due to the better crystallinity of Pt shells as well as the alloy effect of Au cores. © 2012 The Royal Society of Chemistry.

  18. Method and device for the determination of the make-up of an alcohol-gasoline mixture, intended for automatic control of engine performance. Precede et dispositif pour determiner la composition d'un melange alcool-essence, adaptes au reglange automatique de moteurs

    Energy Technology Data Exchange (ETDEWEB)

    Degobert, P.; Maute, M.; Banet, G.

    1987-09-22

    This patent describes a process for determining the composition of an alcohol-gasoline mixture. According to this process, a light beam is emitted across the mixture for at least one wavelength. This wavelength is chosen in the wavelength interval corresponding to the near infrared and the degree of absorptivity is linked to the alcohol content of the mixture. Such a process of determination can be used to regulate automatically the parameters of operation of an internal combustion engine fueled by an alcohol-gasoline mixture. In order to do this, a light beam is emitted across the mixture fueling the engine, the degree of absorptivity of this beam in a wavelength band chosen in the near infrared range is determined, and the regulation of the operating parameters of the engine is directed as a function of the absorptivity thus measured. An apparatus for carrying out such automatic regulation is also disclosed.

  19. The Au-S bond in biomolecular adsorption and electrochemical electron transfer

    DEFF Research Database (Denmark)

    Ford, M. J.; Hush, N. S.; Marcuccio, S.

    is the electronic structure of the Au-S link and the packing of the SAMs. We have, first disentangled a wealth of data to identify the nature of the core Au-S contact. All data suggest that the electronic Au-S link is dominated by a Au(0)-thiyl radical with strong vander Waals forces and not by a Au...

  20. Correlation of magnetism and structure for ultra thin Au/Co/Au films: Evidence for magnetoelastic effects

    Energy Technology Data Exchange (ETDEWEB)

    Sakamaki, M; Konishi, T; Fujikawa, T [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoicho, Inage, Chiba 263-8522 (Japan); Persson, A; Andersson, C; Karis, O; Arvanitis, D [Department of Physics and Material Science, Uppsala University, Box 530, SE-75121 Uppsala (Sweden); Rossner, H; Holub-Krappe, E, E-mail: holub-krappe@helmholtz-berlin.d [Helmholtz Centre Berlin for Materials and Energy, Lise Meitner Campus, Glienicker Str. 100, D-14109 Berlin (Germany)

    2009-11-15

    The spin-reorientation transition of thin Au/Co/Au films, grown in-situ on W(110), is studied in XMCD and EXAFS experiments. At 300 K, for in-situ grown Co on a Au(111) film, the dominant easy magnetization direction was found to be in the surface plane, for the uncapped Co/Au bilayers. This is a novel observation, in terms of easy magnetization direction for low thickness Co on Au. After capping with Au, a sizeable out-of-plane magnetization is observed below a thickness of four atomic Co layers. When the spin-reorientation transition occurs because of Au capping, a 5 A thin Co layer undergoes structural changes of lattice parameters {Delta}a/a = -1.2 % and {Delta}c/c = +6.6 %. The observation of structural changes which accompany the spin reorientation transition, contradicts previous work on Co/Au(111), and allows to quantify the magnetoelastic energy contribution, connected with the presence of the Co/Au interface.

  1. Role of ceramic matrix and Au fraction on the morphology and optical properties of cosputtered Au-ceramic thin films

    Science.gov (United States)

    Hazra, S.; Gibaud, A.; Sella, C.

    2007-06-01

    Surface sensitive x-ray scattering studies were carried out to understand the morphology of cermet thin films prepared by cosputtering metallic gold and ceramic materials on float glass substrates. It has been observed that the morphology of Au clusters in cermet thin films depends strongly on the matrix during growth, even if, all other conditions are kept identical. In particular, nearly isotropic growth of Au clusters, to form nanoparticles, is found in silica and alumina matrices, while anisotropic columnar-like growth of Au clusters, to form a nanorod-like shape, is found in a titanium oxide matrix. Thickness of the films was also found very different, which is likely to be related to the different sputtering yields of the ceramic materials. The volume fraction of Au estimated from the electron density profile shows that the total volume or the amount of Au is different in films of different ceramic matrices. This suggests that even the sputtering yield of Au is very different in the presence of different ceramic atmosphere, which is likely to be responsible for having a different morphology of Au clusters in different matrices. Optical absorption spectra of the films, on the other hand, show linear dependence of the absorption peak position with the volume fraction of Au and independent of both the ceramic matrix and morphology of Au clusters.

  2. Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form

    DEFF Research Database (Denmark)

    Reimers, Jeffrey R.; Ford, Michael J.; Halder, Arnab

    2016-01-01

    The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates...... that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method...

  3. Production et commercialisation durables de l'indigo au Salvador ...

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

    Asociación Balsamo tente de mettre au point un nouveau modèle agroindustriel de production d'indigo, au Salvador, qui permettra aux petits exploitants de faire de cette culture leur principale source de revenus. Le projet permettra à une équipe ...

  4. Fuzzy analytical hierarchy process and GIS for predictive cu -au ...

    African Journals Online (AJOL)

    In the Mokhtaran sheet for predictive Cu -Au porphyry this method was used. Combining this way with geographic information systems GIS is effective approach for predictive Mineral prospectively mapping (MPM) for Cu -Au porphyry. For preparing MPM, the criteria were geological data (host rocks, heat rocks, alteration), ...

  5. AuAg alloy nanomolecules with 38 metal atoms

    Science.gov (United States)

    Kumara, Chanaka; Dass, Amala

    2012-06-01

    Au38-nAgn(SCH2CH2Ph)24 alloy nanomolecules were synthesized, purified and characterized by MALDI TOF mass spectrometry. Similar to 25 and unlike 144 metal atom count AuAg alloy nanomolecules, incorporation of Ag atoms here results in loss or smearing out of distinct UV-vis features. We propose that the short and long staples contain Au atoms, while the inner core consists of both Au and Ag atoms.Au38-nAgn(SCH2CH2Ph)24 alloy nanomolecules were synthesized, purified and characterized by MALDI TOF mass spectrometry. Similar to 25 and unlike 144 metal atom count AuAg alloy nanomolecules, incorporation of Ag atoms here results in loss or smearing out of distinct UV-vis features. We propose that the short and long staples contain Au atoms, while the inner core consists of both Au and Ag atoms. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11781a

  6. Synthesis and stability of monolayer-protected Au38 clusters

    NARCIS (Netherlands)

    Toikkanen, O.; Ruiz, V.; Rönnholm, G.; Kalkkinen, N.; Liljeroth, P.W.|info:eu-repo/dai/nl/314007423; Quinn, B.M.

    2008-01-01

    A synthesis strategy to obtain monodisperse hexanethiolate-protected Au38 clusters based on their resistance to etching upon exposure to a hyperexcess of thiol is reported. The reduction time in the standard Brust−Schiffrin two-phase synthesis was optimized such that Au38 were the only clusters that

  7. Facile Growth of Multi-twined Au Nanostructures

    Indian Academy of Sciences (India)

    We describe a facile growth of chain-like Au nanostructures and their spontaneous transformation to multi-twined nanostructure using a mild reducing agent bisphenol A (BPA). The growth Au nanostructures involves the chemical reduction of HAuCl4 by BPA in the presence of cetyltrimethylammonium bromide (CTAB) as ...

  8. Microstructural evolution of eutectic Au-Sn solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Geon [Univ. of California, Berkeley, CA (United States)

    2002-05-01

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  9. Giant magnetoresistance of dissymmetrical Co/Au multilayers

    Science.gov (United States)

    Kolb, E.; Walker, M. J.; Vélu, E.; Howson, M. A.; Veillet, P.; Greig, D.; Renard, J. P.; Dupas, C.

    1996-04-01

    Results are presented for the magnetoresistance (MR) of sapphire/Nb 3/Cu 3/Au 8/(Co/Au 8) n dissymmetrical multilayers built by alternating a 0.3 nm discontinuous Co layer with a 0.7 nm continuous one. The observed enhanced MR is related to a higher spin scattering asymmetry for the granular Co layers.

  10. CO oxidation on Alsbnd Au nano-composite systems

    Science.gov (United States)

    Rajesh, C.; Majumder, C.

    2018-03-01

    Using first principles method we report the CO oxidation behaviour of Alsbnd Au nano-composites in three different size ranges: Al6Au8, Al13Au42 and a periodic slab of Alsbnd Au(1 1 1) surface. The clusters prefer enclosed structures with alternating arrangement of Al and Au atoms, maximising Auδ-sbnd Alδ+ bonds. Charge distribution analysis suggests the charge transfer from Al to Au atoms, corroborated by the red shift in the density of states spectrum. Further, CO oxidation on these nano-composite systems was investigated through both Eley - Rideal and Langmuir Hinshelwood mechanism. While, these clusters interact with O2 non-dissociatively with an elongation of the Osbnd O bond, further interaction with CO led to formation of CO2 spontaneously. On contrary, the CO2 evolution by co-adsorption of O2 and CO molecules has a transition state barrier. On the basis of the results it is inferred that nano-composite material of Alsbnd Au shows significant promise toward effective oxidative catalysis.

  11. Growth and structure of Co/Au magnetic thin films; Croissance et structure des couches minces magnetiques Co/Au

    Energy Technology Data Exchange (ETDEWEB)

    Marsot, N

    1999-01-14

    We have studied the growth and the crystallographic structure of magnetic ultra thin cobalt/gold films (Co/Au), in order to investigate the correlations between their magnetic and structural properties. Room temperature (R.T.) Co growth on Au (111) proceeds in three stages. Up to 2 Co monolayers (ML), a bilayer island growth mode is observed. Between 2 and 5 ML, coalescence of the islands occurs, covering the substrate surface and a Co/Au mixing is observed resulting from the de-construction of the Herringbone reconstruction. Finally, beyond 5 ML, the CoAu mixing is buried and the Co growth continues in a 3-D growth. Annealing studies at 600 K on this system show a smoothing effect of the Co film, and at the same time, segregation of Au atoms. The quality of the Co/Au interface (sharpness) is not enhanced by the annealing. The local order was studied by SEXAFS and the long range order by GIXRD showing that the Co film has a hexagonal close packed structure, with an easy magnetization axis perpendicular to the surface. From a local order point of view, the Co grows with an incoherent epitaxy and keeps its own bulk parameters. The GIXRD analysis shows a residual strain in the Co film of 4%. The difference observed between the local order analysis and the long range order results is explained in terms of the low dimensions of the diffracting domains. The evolution of film strains, as a function of the Co coverage, shows a marked deviation from the elastic strain theory. Modification of the strain field in the Co film as a function of the Au coverage is studied by GIXRD analysis. The Au growth study, at R.T., shows no evidence of a Au/Co mixing in the case of the Au/Co interface. The Au overlayer adopts a twinned face centred cubic structure on the rough Co film surface. (author)

  12. Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC.

    Science.gov (United States)

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-08-15

    We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.

  13. Au@PdOx with a PdOx-rich shell and Au-rich core embedded in Co3O4 nanorods for catalytic combustion of methane.

    Science.gov (United States)

    Yang, Nating; Liu, Jingwei; Sun, Yuhan; Zhu, Yan

    2017-02-09

    Au@PdOx with a PdOx-rich shell and Au-rich core nested in Co3O4 nanorods exhibited enhanced catalytic performance in the reaction of methane catalytic combustion, compared to monometallic Pd or Au/Co3O4 nanorods as well as conventional PdAu/Co3O4 nanorods. The superior catalysis of Au@PdOx/Co3O4 nanorods is mainly due to the architectural style of the PdOx-rich shell and Au-rich core, which shows strong interaction of Pd, Au, and Co3O4.

  14. Panorama du roman policier au Mexique

    OpenAIRE

    Lara-Alengrin, Alba

    2013-01-01

    Malgré sa diffusion depuis les années quarante par des collections de poche autochtones, le roman policier fut longtemps, au Mexique, un genre méprisé par la critique et les écrivains. Paco Ignacio Taibo II est le premier écrivain mexicain a légitimer et valoriser le genre policier, en particulier le roman noir, qui connaît simultanément un regain d’intérêt critique et commercial. Ce changement de perception vis-à-vis du roman noir s’accompagne de la création d’un nouveau terme pour le qualif...

  15. Interface stress in Au/Ni multilayers

    DEFF Research Database (Denmark)

    Schweitz, K.O.; Böttiger, J.; Chevallier, J.

    2000-01-01

    The effect of intermixing on the apparent interface stress is studied in -textured dc-magnetron sputtered Au/Ni multilayers by use of two methods commonly used for determining interface stress. The method using profilometry and in-plane x-ray diffraction does not take intermixing...... into account and yields an apparent interface stress of -8.46 +/- 0.99 J m(-2). However, observed discrepancies between model calculations and measured high-angle x-ray diffractograms indicate intermixing, and by use of the profilometry and sin(2) psi method the real interface stress value of -2.69 +/- 0.43 J...... m(-2) is found. This method also reveals a significant and systematic change of the stress-free lattice parameter of both constituents as a function of modulation period which is shown to account for the difference between the two findings. The method using in-plane diffraction is thus shown...

  16. La Physique au LHC - Partie I

    CERN Multimedia

    CERN. Geneva

    2004-01-01

    Le LHC devrait permettre l'observation du boson de Higgs et pouvoir lever le voile sur l'un des scénarios de nouvelle physique présentés dans la cours précédent. Ce cours détaillera les perspectives de physique au LHC (découvertes possibles et mesures de précision) ainsi que les méthodes et difficultés expérimentales. L'accent sera mis sur les problèmes liés à la brisure de la symétrie electrofaible. Les possibilités de développement futur à plus haute luminosité et/ou énergie seront également discutées.

  17. and Au nanoparticles for SERS applications

    Directory of Open Access Journals (Sweden)

    Fazio Enza

    2018-01-01

    Full Text Available The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

  18. Une barque au bout du lac

    OpenAIRE

    El-Kharrat, Edouard

    2008-01-01

    Quand la terre resplendit sous le soleil et que vint le jour, je m'en fus vers l'étang. C'est là que je la vis, l'inhumaine. Ma chair frémit quand je la regardai. Sa peau était fraîche et douce. Et depuis son amour vit toujours en mon corps. L'éblouissement qui s'écoulait pourtant par la voûte du monde avait un instant pâli derrière une blanche nuée. Et l'auberge, grêlée, murs de pierre grise, larges portes au treillis vermoulu mouchetées de trous creusé par le soleil et le vent salé, se dres...

  19. Unique Properties of Core Shell Ag@Au Nanoparticles for the Aptasensing of Bacterial Cells

    National Research Council Canada - National Science Library

    Hamidi-Asl, Ezat; Dardenne, Freddy; Pilehvar, Sanaz; Blust, Ronny; De Wael, Karolien

    2016-01-01

    ...) such as gold nanoparticles (Au), silver nanoparticles (Ag), hollow gold nanospheres (HGN), hollow silver nanospheres (HSN), silver–gold core shell (Ag@Au), gold–silver core shell (Au@Ag), and silver...

  20. Spin-polarized ballistic conduction through correlated Au-NiMnSb-Au heterostructures

    Science.gov (United States)

    Morari, C.; Appelt, W. H.; Östlin, A.; Prinz-Zwick, A.; Schwingenschlögl, U.; Eckern, U.; Chioncel, L.

    2017-11-01

    We examine the ballistic conduction through Au-NiMnSb-Au heterostructures consisting of up to four units of the half-metallic NiMnSb in the scattering region, using density functional theory (DFT) methods. For a single NiMnSb unit the transmission function displays a spin polarization of around 50 % in a window of 1 eV centered around the Fermi level. By increasing the number of layers, an almost complete spin polarization of the transmission is obtained in this energy range. Supplementing the DFT calculations with local electronic interactions, of Hubbard-type on the Mn sites, leads to a hybridization between the interface and many-body states. The significant reduction of the spin polarization seen in the density of states is not apparent in the spin polarization of the conduction electron transmission, which suggests that the hybridized interface and many-body induced states are localized.

  1. On Productions of Net-Baryons in Central Au-Au Collisions at RHIC Energies

    Directory of Open Access Journals (Sweden)

    Ya-Hui Chen

    2015-01-01

    Full Text Available The transverse momentum and rapidity distributions of net-baryons (baryons minus antibaryons produced in central gold-gold (Au-Au collisions at 62.4 and 200 GeV are analyzed in the framework of a multisource thermal model. Each source in the model is described by the Tsallis statistics to extract the effective temperature and entropy index from the transverse momentum distribution. The two parameters are used as input to describe the rapidity distribution and to extract the rapidity shift and contribution ratio. Then, the four types of parameters are used to structure some scatter plots of the considered particles in some three-dimensional (3D spaces at the stage of kinetic freeze-out, which are expected to show different characteristics for different particles and processes. The related methodology can be used in the analyses of particle production and event holography, which are useful for us to better understand the interacting mechanisms.

  2. Spin-polarized ballistic conduction through correlated Au-NiMnSb-Au heterostructures

    KAUST Repository

    Morari, C.

    2017-11-20

    We examine the ballistic conduction through Au-NiMnSb-Au heterostructures consisting of up to four units of the half-metallic NiMnSb in the scattering region, using density functional theory (DFT) methods. For a single NiMnSb unit the transmission function displays a spin polarization of around 50% in a window of 1eV centered around the Fermi level. By increasing the number of layers, an almost complete spin polarization of the transmission is obtained in this energy range. Supplementing the DFT calculations with local electronic interactions, of Hubbard-type on the Mn sites, leads to a hybridization between the interface and many-body states. The significant reduction of the spin polarization seen in the density of states is not apparent in the spin polarization of the conduction electron transmission, which suggests that the hybridized interface and many-body induced states are localized.

  3. PHENIX Measurements of Single Electrons from Charm and Bottom Decays at Midrapidity in Au + Au Collisions

    Science.gov (United States)

    McGlinchey, D.

    2016-12-01

    Heavy quarks are an ideal probe of the quark gluon plasma created in heavy ion collisions. They are produced in the initial hard scattering and therefore experience the full evolution of the medium. PHENIX has previously measured the modification of heavy quark production in Au+Au collisions at √{sNN} = 200 GeV via electrons from semileptonic decays, which indicated substantial modifications of the parent hadron momentum distribution. The PHENIX barrel silicon vertex detector (VTX), installed in 2011, allows for the separation of electrons from charm and bottom hadron decays through the use of displaced vertex measurements. These proceedings present the results of the completed analysis of the 2011 data set using the VTX.

  4. PHENIX results on low pT direct photons in Au + Au collisions

    Science.gov (United States)

    Petti, Richard

    2016-12-01

    Since soft photons are unmodified once produced in heavy ion collisions, they give information about the entire thermal evolution of the medium. Excess photon yield over the expectation from initial hard scattering has been measured by PHENIX. In addition, PHENIX has measured a large azimuthal anisotropy, v2, of these soft photons with respect to the reaction plane. The large yield and v2 have been difficult to describe quantitatively and raise important questions about the early time dynamics in the medium. It is thus important to make more differential measurements to distinguish various potential explanations for this thermal photon puzzle. In this proceedings, we present yields, v2, and v3 of direct photons from √{sNN} = 200 GeV Au + Au collisions.

  5. $\\Upsilon$ production in p+p and Au+Au collisions in STAR

    CERN Document Server

    Das, Debasish

    2008-01-01

    The study of quarkonium production in relativistic heavy ion collisions provides insight into the properties of the produced medium. The lattice studies show a sequential suppression of quarkonia states when compared to normal nuclear matter; which further affirms that a full spectroscopy including bottomonium can provide us a better thermometer for the matter produced under extreme conditions in relativistic heavy ion collisions. With the completion of the STAR Electromagnetic Calorimeter and with the increased luminosity provided by RHIC in Run 6 and 7, the study of $\\Upsilon$ production via the di-electron channel becomes possible. We present the results on $\\Upsilon$ measurements in p+p collisions (from Run 6) along with the first results from Au+Au collisions (in Run 7) at $\\sqrt{s_{\\rm{NN}}} = 200$ GeV from the STAR experiment.

  6. Un nouvel oxyde naturel de Au et Sb

    Science.gov (United States)

    Johan, Zdenek; Šrein, Vladimir

    1998-04-01

    A gold-antimony X-ray amorphous oxide, resulting from a hydrothermal alteration of aurostibite, AuSb 2, occurs in the Krásná Hora gold deposit, Czech Republic. Its reflectivity is close to that of goethite. The average composition obtained by electron microprobe analyses (wt. %) is: Au - 68.32; Cu - 0.10; Sb - 21.26; As - 0.30; Si - 0.21; O - 8.44; total 98.63. This yields the empirical formula (Au 0.677Cu 0.003Sb 0.341As 0.008) 1.029O. The[(Au + Cu)/(Sb + As)] at ratio varies from 1.86 to 1.95. Among possible formulae satisfying the equilibrium of charges, that implying unique valence states for Au and/or Sb was retained. It can be written Au 1+2Sb 3+O 2(OH) with the theoretical composition (wt, %): Au - 69.76; Sb - 21.54; O - 8.50; H - 0.20. This Au- and Sb-bearing oxide is associated with native gold, electrum, aurostibite, arsenopyrite and pyrite in a quartz gangue. The powder pattern of AuSbO 3 was indexedon an orthorhombic unit-cell with a = 5.00(2); b = 12.46(4); c = 5.43(2) Å, Z = 4, Q calc = 7.20 g.cm 3, assuming a replacement of Sb 3+ by Au 3+ in the valentinite-type crystal structure.

  7. Devenir De l'azote de L'engrais enrichi au n applique au tournesol ...

    African Journals Online (AJOL)

    L'utilisation de I' azote de I' engrais par la culture de toumesol a ete appreciee par Ia determination du coefficient d'utilisation apparent (CUA) estime par Ia methode de difference et du coefficient d'utilisation reel (CUR) estime par Ia methode isotopique. 80 kg N ha-1 a 4.87% d'atomes en exces de 15N ont ete appliques au ...

  8. Mise au point d'un test in vitro de comportement au sel de quatre ...

    African Journals Online (AJOL)

    agrumes, en termes de résistance à la salinité in vitro au niveau des cals et des cellules cultivées parallèlement sur milieu liquide et solide. Méthodologie et résultat : À cet égard, des cals de quatre génotypes d'agrumes : mandarinier Cléopâtre ...

  9. Seropositivite au vih et grossesse au Togo: vecu et representation a ...

    African Journals Online (AJOL)

    Introduction : Ce travail avait pour objectifs d'identifier les indicateurs de la représentation et du vécu des femmes enceintes séropositives d'une part, et de rechercher un lien entre ces indicateurs chez ces femmes au sud du Togo. Méthodologie : Le cadre de notre étude ont été l'hôpital de Bè, le centre de santé de Lomé, ...

  10. Les Modalites Evolutives Du Zona Au Cours De L\\'infection A Vih Au ...

    African Journals Online (AJOL)

    Introduction et But Peu d\\'informations sont disponibles sur les complications du zona et la prise en charge globale de cette maladie chez les patients VIH-positifs dans les pays d\\'Afrique sub Saharienne à l\\'instar du Cameroun. Le taux de séroprévalence du VIH dans la population adulte générale au Cameroun à été ...

  11. Characterization of Au3+ species in Au/C catalysts for the hydrochlorination reaction of acetylene

    OpenAIRE

    Conte, M.; Davies, C.J.; Morgan, D.J.; Carley, A.F.; Johnston, P.; Hutchings, G.J.

    2014-01-01

    A set of Au/C catalysts for the gas phase hydrochlorination of acetylene to vinyl chloride monomer were prepared using a range of strong acids as impregnating solvents and varying the preparation drying temperature. The most active catalyst is the material prepared using aqua regia as solvent with an intermediate drying temperature of 140 °C. The effects of the catalyst preparation parameters on the catalytic activity are examined using XPS and TPR as analytical tools. In particular, the use ...

  12. Au Kenya, des oiseaux nuisent à une culture adaptée au climat ...

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

    23 août 2013 ... KITUI, Kenya (Thomson Reuters Foundation) – Le gadam, une variété de sorgho à croissance rapide résistante à la sécheresse, a été introduit au Kenya comme solution d'adaptation aux changements climatiques. Or, il se trouve que le gadam comporte un inconvénient imprévu : les oiseaux sauvages ...

  13. Emploi et revenu en Bolivie, au Paraguay et au Pérou : analyse des ...

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

    Comme beaucoup d'autres pays d'Amérique latine, la Bolivie, le Paraguay et le Pérou ont entrepris des réformes structurelles au cours des années 1980 et 1990 dans le but d'atteindre la stabilité macroéconomique et de susciter la croissance économique. On s'attendait à ce que la croissance s'accompagne d'emplois ...

  14. Amélioration de la nutrition au Cambodge au moyen de l ...

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

    Le régime alimentaire des ménages en milieu rural au Cambodge est habituellement pauvre en protéines et en micronutriments, et il en résulte des taux élevés de retard de croissance chez les enfants et d'anémie chez les femmes. Studies. Biochemical correlates of anemia in Cambodian women of reproductive age ...

  15. Biosynthesis of Au, Ag and Au-Ag nanoparticles using edible mushroom extract

    Science.gov (United States)

    Philip, Daizy

    2009-07-01

    Integration of green chemistry principles to nanotechnology is one of the key issues in nanoscience research. There is growing need to develop environmentally benign metal nanoparticle synthesis process that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on extracellular synthesis method for the preparation of Au, Ag and Au-Ag nanoparticles in water, using the extract of Volvariella volvacea, a naturally occurring edible mushroom, as reducing and protecting agents. Gold nanoparticles of different sizes (20-150 nm) and shapes from triangular nanoprisms to nearly spherical and hexagonal are obtained by this novel method. The size and shape of gold nanoparticles are also found to depend on temperature of the extract. The silver nanoparticles are spherical with size ˜15 nm. There is increased productivity of nanoparticles as shown by sharp and intense surface plasmon resonance bands for the nanoparticles prepared using an excess of the extract. The Au-Ag nanoparticles prepared by co-reduction has only one plasmon band due to alloying of the constituents. All the synthesized nanoparticles are found to be photoluminescent and are highly crystalline as shown by SAED and XRD patterns with fcc phase oriented along the (1 1 1) plane. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. It is found that Au nanoparticles are bound to proteins through free amino groups and silver nanoparticles through the carboxylate group of the amino acid residues. The position and intensity of the emission band is found to depend on composition of the nanoparticles indicating the possible use in therapeutic applications.

  16. Prévention de la violence chez les jeunes au Guatemala, au ...

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

    Même si les gouvernements associent la plupart de ces infractions au crime organisé, aux gangs de rue et aux criminels de droit commun, ils ne disposent que de peu de preuves pour étayer leurs conclusions, étant donné que leurs capacités de recherche sont extrêmement faibles. D'ailleurs, le taux de crimes impunis (ne ...

  17. Direct virtual photon production in Au plus Au collisions at root s(NN)=200 GeV STAR Collaboration

    Czech Academy of Sciences Publication Activity Database

    Adamczyk, L.; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Federič, Pavol; Federičová, P.; Harlenderová, A.; Kocmánek, Martin; Kvapil, J.; Lidrych, J.; Rusňák, Jan; Rusňáková, O.; Šaur, Miroslav; Šimko, Miroslav; Šumbera, Michal; Trzeciak, B. A.

    2017-01-01

    Roč. 770, JUL (2017), s. 451-458 ISSN 0370-2693 R&D Projects: GA ČR GA13-20841S Institutional support: RVO:61389005 Keywords : STAR collaboration * transverse mementum * Au Au collisions Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 4.807, year: 2016

  18. Exécution de penalties et de tirs au but au football : maîtrise ...

    African Journals Online (AJOL)

    Exécution de penalties et de tirs au but au football : maîtrise technique ou gestion des émotions chez les tireurs et les gardiens de but. KP Edoh, F Messan, F Dosseville, L Tanimomo, CH Gnidete ...

  19. Two-pion correlations in Au + Au collisions at 10.8 GeV/c per nucleon

    CERN Document Server

    Barrette, J; Bennett, S; Bersch, R; Braun-Munzinger, P; Chang, W C; Cleland, W E; Cole, J D; Cormier, T M; Dávid, G; Dee, J; Dietzsch, O; Drigert, M W; Gilbert, S J; Hall, J R; Hemmick, T K; Herrmann, N; Hong, B H; Jiang, C L; Johnson, S C; Kwon, Y; Lacasse, R; Lukaszew, A; Li, Q; Ludlam, Thomas W; McCorkle, S; Mark, S K; Mathéus, R D; Miskowiec, D; O'Brien, E; Panitkin, S; Piazza, T; Pollack, M E; Pruneau, C A; Rao, M N; Rosati, M; Da Silva, N C; Sedykh, S N; Sonnadara, U; Stachel, J J; Takagui, E M; Trzaska, M; Voloshin, S A; Vongpaseuth, T B; Wang, G; Wessels, J P; Woody, C L; Xu, N; Zhang, Y; Zou, C

    1997-01-01

    Two-particle correlation functions for positive and negative pions have been measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed using one- and three-dimensional correlation functions. From the results of the three-dimensional fit the phase space density of pions was calculated. It is consistent with local thermal equilibrium.

  20. Two-pion correlations in Au+Au collisions at 10.8 GeV/c per nucleon

    OpenAIRE

    E877 Collaboration; Barrette, J.; Bellwied, R.; Bennett, S.; Bersch, R.; Braun-Munzinger, P.; Chang, W. C.; Cleland, W. E.; Cole, J. D.; Cormier, T. M.; David, G.; Dee, J.; Dietzsch, O.; Drigert, M. W.; Gilbert, S.

    1997-01-01

    Two-particle correlation functions for positive and negative pions have been measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed using one- and three-dimensional correlation functions. From the results of the three-dimensional fit the phase space density of pions was calculated. It is consistent with local thermal equilibrium.

  1. Identified particles in Au+Au collisions at {radical}S{sub NN} = 200 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Wosiek, Barbara; Back, B.B.; Baker, M.D.; Barton, D.S.; Betts, R.R.; Ballintijn, M.; Bickley, A.A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M.P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G.A.; Henderson, C.; Hofman, D.J.; Hollis, R.S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C.M.; Manly, S.; McLeod, D.; Michalowski, J.; Mignerey, A.C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I.C.; Pernegger, H.; Reed, C.; Remsberg, L.P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S.G.; Steinberg, P.; Stephans, G.S.F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G.J. van; Verdier, R.; Wadsworth, B.; Wolfs, F.L.H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A.H.; Wysouch, B

    2003-03-10

    The yields of identified particles have been measured at RHIC for Au+Au collisions at {radical}S{sub NN} = 200 GeV using the PHOBOS spectrometer. The ratios of antiparticle to particle yields near mid-rapidity are presented. The first measurements of the invariant yields of charged pions, kaons and protons at very low transverse momenta are also shown.

  2. Neutron diffraction study of La 4LiAuO 8: Understanding Au 3+ in an oxide environment

    Science.gov (United States)

    Kurzman, Joshua A.; Moffitt, Stephanie L.; Llobet, Anna; Seshadri, Ram

    2011-06-01

    Owing to gold's oxophobicity, its oxide chemistry is rather limited, and elevated oxygen pressures are usually required to prepare ternary and quaternary oxide compounds with gold ions. The Au 3+ oxide, La 4LiAuO 8, is remarkable both because it can be prepared at ambient pressure in air, and because of its unusual stability toward thermal decomposition and reduction. The structure of La 4LiAuO 8 was established by Pietzuch et al. using single crystal X-ray diffraction [1]. The compound adopts an ordered modification of the Nd 2CuO 4 structure, containing two-dimensional sheets in which AuO 4 square planes are separated from one another by LiO 4 square planes. In light of the meager X-ray scattering factors of Li and O, relative to La and Au, we report here a neutron powder diffraction study of La 4LiAuO 8, definitively confirming the structure. To our knowledge, this is the first reported neutron diffraction study of any stoichiometric oxide compound of gold. X- N maps, which make use of nuclear positions obtained from Rietveld refinement of time-of-flight neutron diffraction data and electron densities obtained from synchrotron X-ray powder diffraction data, point to the highly covalent nature of the Au-O bonding in La 4LiAuO 8. This is in good agreement with charge densities and Bader charges obtained from full density functional relaxation of the structure.

  3. Promotion of Phenol Photodecomposition over TiO2 Using Au, Pd, and AuPd Nanoparticles

    DEFF Research Database (Denmark)

    Su, Ren; Tiruvalam, Ramchandra; He, Qian

    2012-01-01

    Noble metal nanoparticles (Au, Pd, AuPd alloys) with a narrow size distribution supported on nanocrystalline TiO2 (M/TiO2) have been synthesized via a sol-immobilization route. The effect of metal identity and size on the photocatalytic performance of M/TiO2 has been systematically investigated u...

  4. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    OpenAIRE

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-01-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction...

  5. Temperature measurement of fragment emitting systems in Au+Au 35 MeV/nucleon collisions

    Science.gov (United States)

    Milazzo, P. M.; Vannini, G.; Azzano, M.; Fontana, D.; Margagliotti, G. V.; Mastinu, P. F.; Rui, R.; Tonetto, F.; Colonna, N.; Botvina, A.; Bruno, M.; D'agostino, M.; Fiandri, M. L.; Gramegna, F.; Iori, I.; Moroni, A.; Dinius, J. D.; Gaff, S.; Gelbke, C. K.; Glasmacher, T.; Huang, M. J.; Kunde, G. J.; Lynch, W. G.; Martin, L.; Montoya, C. P.; Xi, H.

    1998-08-01

    We report on the results of experiments performed to investigate the Au+Au 35 MeV/nucleon reaction. The reaction products generated in the disassembly of the unique source formed in central collisions and those coming from the decay of the quasiprojectile in peripheral and midperipheral ones (five different impact parameters) were identified through a careful data selection based on the study of energy and angular distributions. The excitation energies of the fragment sources have been extracted through a calorimetric method and by means of a comparison with model calculations. The nuclear temperatures of these decaying systems have been measured from the relative isotopic abundances and, also for central collisions, from the relative populations of excited states. The temperatures of the quasiprojectile disassembling systems are slowly increasing going towards smaller impact parameter. The relationship between temperature and excitation energy seems to be almost independent of the characteristics of the emitting source. The extracted caloric curve shows a slow monotonic increase with increasing excitation energy. A comparison with data derived from Au fragmentation at much higher incident energies is discussed.

  6. Au@AuPt nanoparticles embedded in B-doped graphene: A superior electrocatalyst for determination of rutin

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianlan; Yang, Guangming; Feng, Shaoping; Shi, Ling; Huang, Zhaolong [School of Science, Honghe University (China); Key Laboratory of Natural Pharamaceutical & Chemical Biology of Yunnan Province Mengzi, Yunnan 661100 (China); Pan, Haibo [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Liu, Wei, E-mail: liuwei4728@126.com [School of Science, Honghe University (China); Key Laboratory of Natural Pharamaceutical & Chemical Biology of Yunnan Province Mengzi, Yunnan 661100 (China)

    2017-04-30

    Highlights: • The formation of B-doped graphene (BG) with high content of a total B species use hydrothermal method with B{sub 2}O{sub 3} as reducing agent and boron source. • BG was exfoliated into monolayer nanosheet impregnated by Au@AuPt NPs because B atom creates a net positive charge to facilitate NPs adsorption. • The dispersed carboxyl units of BG can form hydrogen bonding with the phenolic hydroxyl groups of rutin, making more rutin participate in reaction. • Au@AuPt NPs can form charge accumulation or valence change on prominent part of the surface, improving the catalytic effect to rutin. • More electroactive sites were generated by doping B atoms into graphene structures, which act as multidimensional electron transport pathways. - Abstract: A hydrothermal approach was used to prepare B-doped graphene with B{sub 2}O{sub 3} as reductant and boron source. Results reveal that the boron atoms have been successfully embedded into graphene with a high content of a total B species (2.85 at.%). Then, B-doped graphene was exfoliated further into monolayer nanosheet by impregnating Au@AuPt core-shell nanoparticles (Au@AuPt NPs) because boron atom creates a net positive charge, which facilitates Au@AuPt NPs adsorption to form Au@AuPt NPs/B-doped graphene hybrid nanocatalysts. After that, the Au@AuPt NPs/B-doped hybrid suspension was dropped on glassy carbon electrode for sensing rutin. In this way, the dispersed carboxyl units of B-doped graphene can form hydrogen bonding with the phenolic hydroxyl groups of rutin, making rutin enrich easily on modified electrode surface to enhance the electrochemical response. At the same time, its electrochemical mechanism on the modified electrode was elucidated using cyclic voltammetry. It was found that its electrochemical behavior on modified electrode surface was a surface-controlled quasi-reversible process, and the charge transfer coefficient (α) and electron transfer number (n) were 0.296 and 2, respectively

  7. Structure and Mobility of Metal Clusters in MOFs: Au, Pd, and AuPd Clusters in MOF-74

    DEFF Research Database (Denmark)

    Vilhelmsen, Lasse; Walton, Krista S.; Sholl, David S.

    2012-01-01

    Understanding the adsorption and mobility of metal–organic framework (MOF)-supported metal nanoclusters is critical to the development of these catalytic materials. We present the first theoretical investigation of Au-, Pd-, and AuPd-supported clusters in a MOF, namely MOF-74. We combine density...... functional theory (DFT) calculations with a genetic algorithm (GA) to reliably predict the structure of the adsorbed clusters. This approach allows comparison of hundreds of adsorbed configurations for each cluster. From the investigation of Au8, Pd8, and Au4Pd4 we find that the organic part of the MOF......’s adsorption energy and diffusion barrier is established, confirming that Au clusters are highly mobile in the MOF-74 framework and Pd clusters are less mobile....

  8. High-temperature stability of Au/Pd/Cu and Au/Pd(P)/Cu surface finishes

    Science.gov (United States)

    Ho, C. E.; Hsieh, W. Z.; Lee, P. T.; Huang, Y. H.; Kuo, T. T.

    2018-03-01

    Thermal reliability of Au/Pd/Cu and Au/Pd(4-6 wt.% P)/Cu trilayers in the isothermal annealing at 180 °C were investigated by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and transmission electron microscopy (TEM). The pure Pd film possessed a nanocrystalline structure with numerous grain boundaries, thereby facilitating the interdiffusion between Au and Cu. Out-diffusion of Cu through Pd and Au grain boundaries yielded a significant amount of Cu oxides (CuO and Cu2O) over the Au surface and gave rise to void formation in the Cu film. By contrast, the Pd(P) film was amorphous and served as a good diffusion barrier against Cu diffusion. The results of this study indicated that amorphous Pd(P) possessed better oxidation resistance and thermal reliability than crystalline Pd.

  9. Au@AuPt nanoparticles embedded in B-doped graphene: A superior electrocatalyst for determination of rutin

    Science.gov (United States)

    Chen, Xianlan; Yang, Guangming; Feng, Shaoping; Shi, Ling; Huang, Zhaolong; Pan, Haibo; Liu, Wei

    2017-04-01

    A hydrothermal approach was used to prepare B-doped graphene with B2O3 as reductant and boron source. Results reveal that the boron atoms have been successfully embedded into graphene with a high content of a total B species (2.85 at.%). Then, B-doped graphene was exfoliated further into monolayer nanosheet by impregnating Au@AuPt core-shell nanoparticles (Au@AuPt NPs) because boron atom creates a net positive charge, which facilitates Au@AuPt NPs adsorption to form Au@AuPt NPs/B-doped graphene hybrid nanocatalysts. After that, the Au@AuPt NPs/B-doped hybrid suspension was dropped on glassy carbon electrode for sensing rutin. In this way, the dispersed carboxyl units of B-doped graphene can form hydrogen bonding with the phenolic hydroxyl groups of rutin, making rutin enrich easily on modified electrode surface to enhance the electrochemical response. At the same time, its electrochemical mechanism on the modified electrode was elucidated using cyclic voltammetry. It was found that its electrochemical behavior on modified electrode surface was a surface-controlled quasi-reversible process, and the charge transfer coefficient (α) and electron transfer number (n) were 0.296 and 2, respectively. This electrochemical sensor for rutin provided a wide linear response range of 2.00 × 10-9-4.00 × 10-6 M with the detection limit (S/N = 3) of 2.84 × 10-10 M. The proposed method was applied successfully to selective determination of rutin in Tablets with acceptable recovery range (97.23-101.65%).

  10. Deep level anomalies in silicon doped with radioactive Au atoms

    CERN Document Server

    Bollmann, J; Henry, M O; McGlynn, E; Knack, S

    1999-01-01

    DLTS investigations on n- and p-type silicon samples implanted with various radioactive Hg isotopes which decay fully or partly through the series Au/Pt/(Ir) are reported. The deep Au-donor level at E/sub v/+0.374(3) eV is observed in all cases. In p-type silicon its energy differs significantly (E/sub v/+0.438(3) eV). Both Au and Pt are found to produce two acceptor levels in n-type material. An additional donor-like level at E/sub v/+0.499(4) eV is shown to be due to Au. In all detected levels, one atom of Au or Pt is involved and the concentration decreases towards crystal surface. A key result is that, despite the presence of the Au donor in the samples, for all decay series involving Au to Pt conversion we have never observed the appearance of the Pt-donor. (6 refs).

  11. SORPTION OF Au(III BY Saccharomyces cerevisiae BIOMASS

    Directory of Open Access Journals (Sweden)

    Amaria Amaria

    2010-07-01

    Full Text Available Au(III sorption by S. cerevisiae biomass extracted from beer waste industry was investigated. Experimentally, the sorption was conducted in batch method. This research involved five steps: 1 identification the functional groups present in the S. cerevisiae biomass by infrared spectroscopic technique, 2 determination of optimum pH, 3 determination of the sorption capacity and energy, 4 determination of the sorption type by conducting desorption of sorbed Au(III using specific eluents having different desorption capacity such as H2O (van der Waals, KNO3 (ion exchange, HNO3 (hydrogen bond, and tiourea (coordination bond, 5 determination of effective eluents in Au(III desorption by partial desorption of sorbed Au(III using thiourea, NaCN and KI. The remaining Au(III concentrations in filtrate were analyzed using Atomic Absorption Spectrophotometer. The results showed that: 1 Functional groups of S. cerevisiae biomass that involved in the sorption processes were hydroxyl (-OH, carboxylate (-COO- and amine (-NH2, 2 maximum sorption was occurred at pH 4, equal to 98.19% of total sorption, 3 The sorption capacity of biomass was 133.33 mg/g (6.7682E-04 mol/g and was involved sorption energy 23.03 kJ mol-1, 4 Sorption type was dominated by coordination bond, 5 NaCN was effective eluent to strip Au(III close to 100%.   Keywords: sorption, desorption, S. cerevisiae biomass, Au(III

  12. Structural, electronic and magnetic properties of Au-based monolayer derivatives in honeycomb structure

    Energy Technology Data Exchange (ETDEWEB)

    Kapoor, Pooja, E-mail: pupooja16@gmail.com; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Centre for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

    2016-05-23

    We present electronic properties of atomic layer of Au, Au{sub 2}-N, Au{sub 2}-O and Au{sub 2}-F in graphene-like structure within the framework of density functional theory (DFT). The lattice constant of derived monolayers are found to be higher than the pristine Au monolayer. Au monolayer is metallic in nature with quantum ballistic conductance calculated as 4G{sub 0}. Similarly, Au{sub 2}-N and Au{sub 2}-F monolayers show 4G{sub 0} and 2G{sub 0} quantum conductance respectively while semiconducting nature with calculated band gap of 0.28 eV has been observed for Au{sub 2}-O monolayer. Most interestingly, half metalicity has been predicted for Au{sub 2}-N and Au{sub 2}-F monolayers. Our findings may have importance for the application of these monolayers in nanoelectronic and spintronics.

  13. Extreme interplanetary rotational discontinuities at 1 AU

    Science.gov (United States)

    Lepping, R. P.; Wu, C.-C.

    2005-11-01

    This study is concerned with the identification and description of a special subset of four Wind interplanetary rotational discontinuities (from an earlier study of 134 directional discontinuities by Lepping et al. (2003)) with some "extreme" characteristics, in the sense that every case has (1) an almost planar current sheet surface, (2) a very large discontinuity angle (ω), (3) at least moderately strong normal field components (>0.8 nT), and (4) the overall set has a very broad range of transition layer thicknesses, with one being as thick as 50 RE and another at the other extreme being 1.6 RE, most being much thicker than are usually studied. Each example has a well-determined surface normal (n) according to minimum variance analysis and corroborated via time delay checking of the discontinuity with observations at IMP 8 by employing the local surface planarity. From the variance analyses, most of these cases had unusually large ratios of intermediate-to-minimum eigenvalues (λI/λmin), being on average 32 for three cases (with a fourth being much larger), indicating compact current sheet transition zones, another (the fifth) extreme property. For many years there has been a controversy as to the relative distribution of rotational (RDs) to tangential discontinuities (TDs) in the solar wind at 1 AU (and elsewhere, such as between the Sun and Earth), even to the point where some authors have suggested that RDs with large ∣Bn∣s are probably not generated or, if generated, are unstable and therefore very rare. Some of this disagreement apparently has been due to the different selection criteria used, e.g., some allowed eigenvalue ratios (λI/λmin) to be almost an order of magnitude lower than 32 in estimating n, usually introducing unacceptable error in n and therefore also in ∣Bn∣. However, we suggest that RDs may not be so rare at 1 AU, but good quality cases (where ∣Bn∣ confidently exceeds the error in ∣Bn∣) appear to be uncommon, and further

  14. Insuffisance renale et infection au vih : Aspects epidemiologique ...

    African Journals Online (AJOL)

    But : Déterminer le profil épidémiologique, clinique et évolutif des personnes séropositives au VIH (PVVIH) présentant une insuffisance rénale (IR) hospitalisées en réanimation médicale au CHU Tokoin de Lomé. Méthodologie : Il s'est agit d'une étude rétrospective concernant les patients séropositives au VIH présentant ...

  15. Radiation effects on dielectric losses of Au-doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Molla, J.; Vila, R.; Ibarra, A. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain). Inst. de Investigacion Basica; Heidinger, R. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Materialforschung

    1998-10-01

    Effects of electron and neutron irradiation on dielectric properties of Au-doped silicon are examined as a function of the frequency between 1 kHz and 150 GHz. The studies compare the Au-doped Si with a high resistivity (HR) pure Si in the as-received state and after electron irradiation. The obtained data for both materials show that electron irradiation and neutron irradiation do not cause degradation of the dielectric loss behaviour, but even improve it. This beneficial effect already observed earlier in pure silicon is also observed in Au-doped silicon. Loss data obtained in-beam under electron irradiation are also reported. (orig.) 15 refs.

  16. Au(111) and Pt(111) surface phase behavior

    DEFF Research Database (Denmark)

    Sandy, A.R.; Mochrie, S.G.J.; Zehner, D.M.

    1993-01-01

    We describe our recent X-ray scattering studies of the structure and phases of the clean Au(111) and Pt(111) surfaces. Below 0.65 of their respective bulk melting temperatures, the Au(111) surface has a well-ordered chevron reconstruction and the Pt(111) surface is unreconstructed. Above...... these temperatures, both surfaces reconstruct to form layers that are isotropically compresses and have only short-range order. Throughout their reconstructed phases, the densities of the Au and Pt(111) surfaces increase with increasing temperature....

  17. Au plasmonics in a WS{sub 2}-Au-CuInS{sub 2} photocatalyst for significantly enhanced hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Zhongzhou [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Zhenxing, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn; Shifa, Tofik Ahmed; Wang, Fengmei; Zhan, Xueying; Xu, Kai; He, Jun, E-mail: wangzx@nanoctr.cn, E-mail: hej@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Liu, Quanlin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-11-30

    Promoting the activities of photocatalysts is still the critical challenge in H{sub 2} generation area. Here, a Au plasmon enhanced photocatalyst of WS{sub 2}-Au-CuInS{sub 2} is developed by inserting Au nanoparticles between WS{sub 2} nanotubes and CuInS{sub 2} (CIS) nanoparticles. Due to the localized surface plasmonic resonance properties from Au nanoparticles, WS{sub 2}-Au-CIS shows the best performance as compared to Au-CIS, CIS, WS{sub 2}-CIS, CIS-Au, WS{sub 2}-Au, and WS{sub 2}-CIS-Au. The surface plasmonic resonance effects dramatically intensify the absorption of visible light and help to inject hot electrons into the semiconductors. Our findings open up an efficient method to optimize the type-II structures for photocatalytic water splitting.

  18. Chemical and electrical characteristics of annealed Ni/Au and Ni/Ir/Au contacts on AlGaN

    Energy Technology Data Exchange (ETDEWEB)

    Ngoepe, P.N.M., E-mail: phuti.ngoepe@up.ac.za [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Meyer, W.E.; Auret, F.D.; Omotoso, E.; Diale, M. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Swart, H.C.; Duvenhage, M.M.; Coetsee, E. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2016-01-01

    The evolution of Ni/Au and Ni/Ir/Au metal contacts deposited on AlGaN was investigated at different annealing temperatures. The samples were studied with electrical and chemical composition techniques. I–V characteristics of the Schottky diodes were optimum after 500 and 600 °C annealing for Ni/Au and Ni/Ir/Au based diodes, respectively. The depth profiles of the contacts were measured by x-ray photoelectron spectroscopy and time of flight secondary ion mass spectroscopy. These chemical composition techniques were used to examine the evolution of the metal contacts in order to verify the influence the metals have on the electrical properties of the diodes. The insertion of Ir as a diffusion barrier between Ni and Au effected the electrical properties, improving the stability of the contacts at high temperatures. Gold diffused into the AlGaN film, degrading the electrical properties of the Ni/Au diode. At 500 °C, the insertion of Ir, however, prevented the in-diffusion of Au into the AlGaN substrate.

  19. Evaluation of the Olympus AU-510 analyser.

    Science.gov (United States)

    Farré, C; Velasco, J; Ramón, F

    1991-01-01

    The selective multitest Olympus AU-510 analyser was evaluated according to the recommendations of the Comision de Instrumentacion de la Sociedad Española de Quimica Clinica and the European Committee for Clinical Laboratory Standards. The evaluation was carried out in two stages: an examination of the analytical units and then an evaluation in routine work conditions. The operational characteristics of the system were also studied.THE FIRST STAGE INCLUDED A PHOTOMETRIC STUDY: dependent on the absorbance, the inaccuracy varies between +0.5% to -0.6% at 405 nm and from -5.6% to 10.6% at 340 nm; the imprecision ranges between -0.22% and 0.56% at 405 nm and between 0.09% and 2.74% at 340 nm. Linearity was acceptable, apart from a very low absorbance for NADH at 340 nm; and the imprecision of the serum sample pipetter was satisfactory.TWELVE SERUM ANALYTES WERE STUDIED UNDER ROUTINE CONDITIONS: glucose, urea urate, cholesterol, triglycerides, total bilirubin, creatinine, phosphate, iron, aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase.The within-run imprecision (CV%) ranged from 0.67% for phosphate to 2.89% for iron and the between-run imprecision from 0.97% for total bilirubin to 7.06% for iron. There was no carryover in a study of the serum sample pipetter. Carry-over studies with the reagent and sample pipetters shows some cross contamination in the iron assay.

  20. Decontamination by fractional distillation of a radioactive mixture of perchlorethylene, bitumen, and sludges from chemical co-precipitations; Decontamination par distillation fractionnee d'un melange radioactif constitue par du perchlorethylene, du bitume et des boues de coprecipitation chimique

    Energy Technology Data Exchange (ETDEWEB)

    Lefillatre, G.; Hullo, R. [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1969-07-01

    It is not possible to incinerate the contaminated organic waste containing chlorine, produced at the Marcoule Centre. The only valid method for these solvents of average activity is fractional distillation. This report presents a pilot fractional distillation plant designed for decontaminating the residual solvents produced by the Centre's Waste Processing Station. These contaminated solvents come from the decontamination of a screw extrusion apparatus with perchlorethylene; this equipment is used for coating the radioactive sludges with bitumen. The pilot plant operates discontinuously and is used to decontaminate the perchlorethylene, to separate the perchlorethylene from the water, and to process the distillation residue. The electrically heated boiler is fitted with a removable base in the form of a disposable container. The installations decontamination factor is 3.4 x 10{sup 6} when solvents with a specific activity of 0.23 Ci/m{sup 3} are used. The average flow-rate for a distillation run is 10 l/hr at atmospheric pressure, and 21 l/hr at a residual pressure of 40 torr. The decontamination factor for the installation is better at atmospheric pressure than in a vacuum. (authors) [French] Les effluents organiques contamines chlores du Centre de Marcoule ne peuvent etre incineres. Le seul mode de traitement qui s'impose pour ces solvants de moyenne activite s'avere etre la distillation fractionnee. Ce rapport presente une installation pilote de distillation fractionnee qui a ete concue pour decontaminer des solvants residuaires provenant de la Station de Traitement des Effluents du Centre. Ces solvants contamines resultent de la decontamination au moyen de perchlorethylene d'une extrudeuse a vis servant a l'enrobage par le bitume des boues radioactives de cette station. L'installation pilote fonctionne en discontinu et assure a la fois la decontamination du perchlorethylene, la separation du perchlorethylene et de l'eau et le

  1. Comparison of the space-time extent of the emission source in $d$$+$Au and Au$+$Au collisions at $\\sqrt{s_{{NN}}}=200$ GeV

    CERN Document Server

    Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Bataineh, H; Alexander, J; Alfred, M; Angerami, A; Aoki, K; Apadula, N; Aramaki, Y; Asano, H; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bandara, N S; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Beaumier, M; Beckman, S; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bhom, J H; Bickley, A A; Black, D; Blau, D S; Bok, J; Bok, J S; Boyle, K; Brooks, M L; Bryslawskyj, J; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Caringi, A; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; del Valle, Z Conesa; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; Daugherity, M S; David, G; Dayananda, M K; DeBlasio, K; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Ding, L; Dion, A; Do, J H; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Feege, N; Fields, D E; Finger, M; Jr., \\,; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gal, C; Gallus, P; Garg, P; Garishvili, I; Ge, H; Giordano, F; Glenn, A; Gong, H; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Grim, G; Perdekamp, M Grosse; Gu, Y; Gunji, T; Guragain, H; Gustafsson, H -Å; Hachiya, T; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Han, S Y; Hanks, J; Hartouni, E P; Hasegawa, S; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Hoshino, T; Huang, J; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Imazu, Y; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Ivanishchev, D; Iwanaga, Y; Jacak, B V; Jeon, S J; Jezghani, M; Jia, J; Jiang, X; Jin, J; Johnson, B M; Jones, T; Joo, E; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Key, J A; Khachatryan, V; Khanzadeev, A; Kihara, K; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, C; Kim, D H; Kim, D J; Kim, E; Kim, E -J; Kim, H -J; Kim, M; Kim, S H; Kim, Y -J; Kim, Y K; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Klatsky, J; Kleinjan, D; Kline, P; Koblesky, T; Kochenda, L; Kofarago, M; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kotov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Lee, S H; Leitch, M J; Leite, M A L; Leitgab, M; Leitner, E; Lenzi, B; Li, X; Lichtenwalner, P; Liebing, P; Lim, S H; Levy, L A Linden; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Makek, M; Malakhov, A; Malik, M D; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Meles, A; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Mikeš, P; Miki, K; Miller, A J; Milov, A; Mishra, D K; Mishra, M; Mitchell, J T; Miyasaka, S; Mizuno, S; Mohanty, A K; Montuenga, P; Moon, H J; Moon, T; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murakami, T; Murata, J; Mwai, A; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakagomi, H; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Nattrass, C; Netrakanti, P K; Newby, J; Nguyen, M; Nihashi, M; Niida, T; Nouicer, R; Novitzky, N; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Koop, J D Orjuela; Oskarsson, A; Ouchida, M; Ozaki, H; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S; Park, S K; Park, W J; Pate, S F; Patel, L; Patel, M; Pei, H; Peng, J -C; Pereira, H; Perepelitsa, D V; Perera, G D N; Peresedov, V; Peressounko, D Yu; Perry, J; Petti, R; Pinkenburg, C; Pinson, R; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Reynolds, D; Riabov, V; Riabov, Y; Richardson, E; Riveli, N; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rowan, Z; Rubin, J G; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Sako, H; Samsonov, V; Sano, S; Sarsour, M; Sato, S; Sato, T; Sawada, S; Schaefer, B; Schmoll, B K; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Sen, A; Seto, R; Sett, P; Sexton, A; Sharma, D; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stepanov, M; Stoll, S P; Sugitate, T; Sukhanov, A; Sumita, T; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, D; Thomas, T L; Timilsina, A; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, M; Towell, R; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vargyas, M; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; Wessels, J; Whitaker, S; White, S N; Winter, D; Wolin, S; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xia, B; Xie, W; Xue, L; Yalcin, S; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; Yoon, I; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zelenski, A; Zhang, C; Zhou, S; Zolin, L

    2014-01-01

    Two-pion interferometry measurements in $d$$+$Au and Au$+$Au collisions at $\\sqrt{s_{{NN}}}=200$ GeV are used to extract and compare the Gaussian source radii R$_{{\\rm out}}$, R$_{{\\rm side}}$, and R$_{{\\rm long}}$, which characterize the space-time extent of the emission sources. The comparisons, which are performed as a function of collision centrality and the mean transverse momentum for pion pairs, indicate strikingly similar patterns for the $d$$+$Au and Au$+$Au systems. They also indicate a linear dependence of R$_{{\\rm side}}$ on the initial transverse geometric size $\\bar{R}$, as well as a smaller freeze-out size for the $d$$+$Au system. These patterns point to the important role of final-state rescattering effects in the reaction dynamics of $d$$+$Au collisions.

  2. Solvent: A Key in Digestive Ripening for Monodisperse Au Nanoparticles

    Science.gov (United States)

    Wang, Peng; Qi, Xuan; Zhang, Xuemin; Wang, Tieqiang; Li, Yunong; Zhang, Kai; Zhao, Shuang; Zhou, Jun; Fu, Yu

    2017-01-01

    This work has mainly investigated the influence of the solvent on the nanoparticles distribution in digestive ripening. The experiments suggested that the solvents played a key role in digestive ripening of Au nanoparticles (Au NPs). For the benzol solvents, the resulting size distribution of Au NPs was inversely related to the solvent polarity. It may be interpreted by the low Gibbs free energy of nanoparticles in the high polarity medium, which was supposedly in favor of reducing the nanoparticles distribution. Through digestive ripening in the highly polar benzol solvent of p-chlorotoluene, monodisperse Au NPs with relative standard deviation (RSD) of 4.8% were achieved. This indicated that digestive ripening was an effective and practical way to prepare high-quality nanoparticles, which holds great promise for the nanoscience and nanotechnology.

  3. Fe magnetic impurity effect in Au atomic sized conductor

    Energy Technology Data Exchange (ETDEWEB)

    Ienaga, Koichiro; Inagaki, Yuji; Kawae, Tatsuya [Department of Applied Quantum Physics, Kyushu University, Moto-oka, Fukuoka 819-0395 (Japan); Tsujii, Hiroyuki, E-mail: te208276@s.kyushu-u.ac.j [Department of Education, Kanazawa University, Kanazawa, 920-1192 (Japan)

    2010-01-01

    We have studied the electrical conductance in Au nanowire containing 0.07 at.%Fe ions (AuFe nanowire) with mechanically controllable break junction technique to investigate the magnetic impurity effects in the atomic-sized conductance. At room temperature, we observe not only conductance steps at the integer multiples of G{sub 0} = 2e{sup 2}/h, but also steps deviating from them in AuFe nanowire. Moreover, these features persist down to T = 4.2 K. The scattering between the conduction electrons and Fe magnetic ions may lift the spin degeneracy of the transmission probability, which is responsible for the deviation. Zero bias anomaly is observed in the AuFe nanowire with the contact diameter larger than {approx}3 nm in the current-voltage (I-V) measurements at T = 4.2 K, which may be caused by Kondo effect.

  4. Hydrogen adsorption on bimetallic PdAu(111) surface alloys

    DEFF Research Database (Denmark)

    Takehiro, Naoki; Liu, Ping; Bergbreiter, Andreas

    2014-01-01

    The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining the stru...... into the physical effects underlying the observed adsorption behavior. Consequences of these findings for the understanding of hydrogen adsorption on bimetallic surfaces in general are discussed.......The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining...... and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight...

  5. On the structure of the thiolated Au15 cluster.

    Science.gov (United States)

    Tlahuice-Flores, Alfredo; Jose-Yacamán, Miguel; Whetten, Robert L

    2013-12-07

    The structure of the Au15-thiolate cluster has been elucidated using a DFT approach, and it is demonstrated to comprise a Au4-tetrahedron core protected solely by the combination of two concatenated staple motifs. The longer motif efficiently wraps the core, and threads the shorter one. The structural assignment is supported by comparison to the powder X-ray diffraction pattern and, via time dependent-DFT calculations, to the optical and chiroptical (CD) absorption spectra. The calculated CD spectrum features a characteristic strong peak centered at 3.48 eV in accordance with the experimental profile. These results confirm the existence of long Au(I)-thiolate motifs as protecting units of small thiolated gold clusters with a thiolate-to-gold ratio comparable to the Au15(SR)13 cluster.

  6. Malformations vasculaires au cours du syndrome de Williams-Beuren

    African Journals Online (AJOL)

    Malformations vasculaires au cours du syndrome de Williams-Beuren: à propos de trois nouvelles observations. Hicham Sator, Fatima Ezzahra Rhouni, Ibitihale Benjouad, Fatima Ezzahra Rhouni, Ibitihale Benjouad, Rachida Dafiri, Latifa Chat ...

  7. Assembling Bare Au Nanoparticles at Positively Charged Templates

    Science.gov (United States)

    Wang, Wenjie; Zhang, Honghu; Kuzmenko, Ivan; Mallapragada, Surya; Vaknin, David

    2016-05-01

    In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits short-range in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), display less in-plane regular packing compared to bare AuNPs.

  8. Assembling Bare Au Nanoparticles at Positively Charged Templates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenjie; Zhang, Honghu; Kuzmenko, Ivan; Mallapragada, Surya; Vaknin, David

    2016-05-26

    In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the chargedinterfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits shortrange in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), display less in-plane regular packing compared to bare AuNPs.

  9. PHENIX results on jets in d + Au

    Energy Technology Data Exchange (ETDEWEB)

    Hanks, J. Ali

    2016-12-15

    We present recently published results [A. Adare, et al., (arXiv:1509.04657)] on fully reconstructed R=0.3 anti-k{sub t} jets measured in p+p and d+Au collisions at 200 GeV center-of-mass energy. The jet yields for four centrality classes along with the p+p reference are presented, as well as both the minimum bias R{sub dAu} and centrality dependent R{sub dAu} and R{sub CP}. We find that while the minimum bias R{sub dA} is consistent with unity, providing a strong constraint on models including cold-nuclear-matter effects or energy loss in small systems, the centrality dependent R{sub dAu} show a striking variation which presents a challenge to models attempting to describe the interplay between soft and hard processes in these systems.

  10. Café-au-lait spots in schoolchildren.

    Science.gov (United States)

    Burwell, R G; James, N J; Johnston, D I

    1982-01-01

    This paper reports a study of café-au-lait spots of a minimum diameter of 1 cm in 732 white schoolchildren. Three groups were identified, according to the number of café-au-lait spots on each child: (1) those with none (74%), (2) those with fewer than 5 (25%), and (3) those with at least 5 (5 children, 2 considered to be normal, and 3 siblings each presumed to have neurofibromatosis, one having died from leukaemia). Excluding the last group, the number of café-au-lait spots in the sample was not significantly related to age or sex. Some support is given for using the number of café-au-lait spots as an empirical threshold to diagnose neurofibromatosis. PMID:6810767

  11. Prolonged reorganization of thiol-capped Au nanoparticles layered structures

    Directory of Open Access Journals (Sweden)

    Sarathi Kundu

    2013-09-01

    Full Text Available Prolonged reorganization behaviour of mono-, di-, tri- and multi-layer films of Au nanoparticles prepared by Langmuir-Blodgett method on hydrophobic Si(001 substrates have been studied by using X-ray scattering techniques. Out-of-plane study shows that although at the initial stage the reorganization occurs through the compaction of the films keeping the layered structure unchanged but finally all layered structures modify to monolayer structure. Due to this reorganization the Au density increases within the nanometer thick films. In-plane study shows that inside the reorganized films Au nanoparticles are distributed randomly and the particle size modifies as the metallic core of Au nanoparticles coalesces.

  12. Ordered Au Nanodisk and Nanohole Arrays: Fabrication and Applications

    KAUST Repository

    Zheng, Yue Bing

    2010-01-01

    We have utilized nanosphere lithography (NSL) to fabricate ordered Au nanodisk and nanohole arrays on substrates and have studied the localized surface plasmon resonance (LSPR) of the arrays. Through these investigations, we demonstrate that the angle- dependent behavior of the LSPR in the Au nanodisk arrays enables real-time observation of exciton-plasmon couplings. In addition, we show that the NSL-fabricated Au nanohole arrays can be applied as templates for patterning micro-/nanoparticles under capillary force. The unique structural and plasmonic characteristics of the Au nanodisk and nano- hole arrays, as well as the low-cost and high-throughput NSL-based nanofabrication technique, render these arrays excellent platforms for numerous engineering applications. © 2010 by ASME.

  13. Programmes de nutrition au sein des centres de sante ...

    African Journals Online (AJOL)

    Au Mali, l'incidence de l'anémie ferriprive au cours de la grossesse est élevée. Pour contribuer à la réduction de cette anémie, un projet visant à renforcer les connaissances des professionnels de la santé en nutrition périnatale et sensibiliser les femmes enceintes pour une bonne supplémentation en fer/folate a été initié ...

  14. Chirurgie endoscopique de l'appareil urinaire au CHU Sylvanus ...

    African Journals Online (AJOL)

    Après un bilan assez limite, des cinq (05) dernières années des activités de chirurgie endoscopique sur l'appareil urinaire, au CHU SO, cette étude analyse les résultats, fait l'état des lieux du matériel endoscopique disponible, des ressources biomédicales au Togo puis situe la place de la maintenance biomédicale dans ...

  15. Relance de l'aquaculture au Sri Lanka | IDRC - International ...

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

    29 avr. 2016 ... Au Sri Lanka, le gouvernement a pour objectif de doubler la consommation de poisson par personne, de 11 kilos à 22 kilos par année, d'ici à la fin de 2014, afin d'augmenter la teneur en protéines du régime alimentaire. Aussi des chercheurs de la Wayamba University, au Sri Lanka, de l'Université de ...

  16. Opportunistes du VIH/SIDA en milieu hospitalier neurologique au ...

    African Journals Online (AJOL)

    Introduction La morbi-mortalité au cours du VIH/sida est souvent liée à des infections opportunistes (IO) neurologiques. L'objectif de cette étude est de déterminer en milieu hospitalier neurologique au Togo, les principales IO et celles qui sont liées à un fort taux de létalité. Méthodes Il s'agissait d'une étude descriptive ...

  17. L'entrepreneuriat au Canada dans le contexte mondial | IDRC ...

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

    24 nov. 2014 ... Également selon le rapport, au Canada, les immigrants de première génération se lancent en affaires dans une proportion plus élevée que le reste de la population, et les femmes participent davantage à l'activité entrepreneuriale que dans les autres pays du G7. En outre, au Canada, contrairement à ce ...

  18. Gouvernance et gestion des ressources communes au Vietnam ...

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

    Gouvernance et gestion des ressources communes au Vietnam. La subvention permettra au Collège d'agriculture et de foresterie de l'Université de Huê de se pencher sur des questions reliées à la gestion des ressources communes et à la pauvreté dans un contexte de décentralisation dans le centre du Vietnam. Le projet ...

  19. Soutien institutionnel au Centre for Population and Environmental ...

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

    Le Centre for Population and Environmental Development (CPED), établi au Nigeria, est un organisme indépendant à but non lucratif qui a été constitué officiellement en 1998. Il se consacre à la recherche-action sur la réduction de la pauvreté et le développement durable au Nigeria en général et dans la région du delta ...

  20. Tabac et pauvreté au Niger | IDRC - International Development ...

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

    Tabac et pauvreté au Niger. La majorité des pays africains sud du Sahara sont au premier stade de l'épidémie du tabac mais la consommation du tabac augmente rapidement. Consciente de la menace mondiale, l'Organisation mondiale de santé (OMS) a initié la Convention-cadre pour la lutte anti-tabac et la majorité des ...

  1. Intrinsic spin Seebeck effect in Au/YIG.

    Science.gov (United States)

    Qu, D; Huang, S Y; Hu, Jun; Wu, Ruqian; Chien, C L

    2013-02-08

    The acute magnetic proximity effects in Pt/YIG compromise the suitability of Pt as a spin current detector. We show that Au/YIG, with no anomalous Hall effect and a negligible magnetoresistance, allows the measurements of the intrinsic spin Seebeck effect with a magnitude much smaller than that in Pt/YIG. The experiment results are consistent with the spin polarized density functional calculations for Pt with a sizable and Au with a negligible magnetic moment near the interface with YIG.

  2. Programmation religieuse au Moyen-Orient : analyse du contenu de ...

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

    Depuis dix ans, la télévision contribue beaucoup au façonnement des attitudes au Moyen-Orient. Dans un contexte de gouvernements autoritaires, d'instabilité politique, de guerre et d'interventions militaires étrangères récurrentes, la télévision a permis la diffusion d'opinions et de points de vue qui, autrement, auraient ...

  3. EST Table: AU311143 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU311143 TT1-27 11/12/09 GO hit GO:0000785(chromatin)|GO:0003682(chromatin binding)...|GO:0005634(nucleus)|GO:0006333(chromatin assembly or disassembly) 10/09/28 n.h 10/08/28 n.h 10/08/27 n.h 10/09/10 n.h 10/09/10 n.h 10/09/10 n.h AU311143 L7 ...

  4. L'entrepreneuriat au Canada dans le contexte mondial | CRDI ...

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

    Également selon le rapport, au Canada, les immigrants de première génération se lancent en affaires dans une proportion plus élevée que le reste de la population, et les femmes participent davantage à l'activité entrepreneuriale que dans les autres pays du G7. En outre, au Canada, contrairement à ce que l'on observe ...

  5. Alloying Au surface with Pd reduces the intrinsic activity in catalyzing CO oxidation

    KAUST Repository

    Qian, Kun

    2016-03-30

    © 2016. Various Au-Pd/SiO2 catalysts with a fixed Au loading but different Au:Pd molar ratios were prepared via deposition-precipitation method followed by H2 reduction. The structures were characterized and the catalytic activities in CO oxidation were evaluated. The formation of Au-Pd alloy particles was identified. The Au-Pd alloy particles exhibit enhanced dispersions on SiO2 than Au particles. Charge transfer from Pd to Au within Au-Pd alloy particles. Isolated Pd atoms dominate the surface of Au-Pd alloy particles with large Au:Pd molar ratios while contiguous Pd atoms dominate the surface of Au-Pd alloy particles with small Au:Pd molar ratios. Few synergetic effect of Au-Pd alloy occurs on catalyzing CO oxidation under employed reaction conditions. Alloying Au with Pd reduces the intrinsic activity in catalyzing CO oxidation, and contiguous Pd atoms on the Au-Pd alloy particles are capable of catalyzing CO oxidation while isolated Pd atoms are not. These results advance the fundamental understandings of Au-Pd alloy surfaces in catalyzing CO oxidation.

  6. Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Boomi, Pandi [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Prabu, Halliah Gurumallesh, E-mail: hgprabu2010@gmail.com [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Manisankar, Paramasivam [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Ravikumar, Sundaram [Department of Oceanography and Coastal Area Studies, School of Marine Sciences, Alagappa University, Thondi Campus 623 409, Tamil Nadu (India)

    2014-05-01

    Graphical abstract: - Highlights: • New method of synthesizing PANI-Ag-Au nanocomposite. • Surface Plasmon resonance and formation of composite at nano level were analyzed. • HR-TEM study revealed uniform distribution of nanoparticles. • PANI-Ag-Au nanocomposite exhibited good antibacterial activity. - Abstract: Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

  7. Au nanoparticles decorated graphene/nickel foam nanocomposite for sensitive detection of hydrogen peroxide

    National Research Council Canada - National Science Library

    Xiaojuan Wang Xinli Guo Jian Chen Chuang Ge Hongyi Zhang Yuanyuan Liu Li Zhao Yao Zhang Zengmei Wang Litao Sun

    The Au nanoparticles decorated graphene(AuNPs@Gr)/nickel foam(Gr/NiF) nanocomposite(AuNPs@Gr/NiF) was prepared by chemical vapor deposition followed by electrophoretic deposition of AuNPs on Gr/NiF...

  8. Controlled electrodeposition of Au monolayer film on ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Qiang; Pang, Liuqing; Li, Man; Zhang, Yunxia; Ren, Xianpei [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China); Liu, Shengzhong Frank, E-mail: szliu@dicp.ac.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China); Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian 116023 (China)

    2016-05-15

    Highlights: • We fabricate Au monolayer film on Ionic liquid substrate using an electrochemical deposition technique. • Au monolayer film was deposited on a “soft substrate” for the first time. • Au monolayer film can contribute extra Raman enhancement. - Abstract: Gold (Au) nanoparticles have been attractive for centuries for their vibrant appearance enhanced by their interaction with sunlight. Nowadays, there have been tremendous research efforts to develop them for high-tech applications including therapeutic agents, sensors, organic photovoltaics, medical applications, electronics and catalysis. However, there remains to be a challenge to fabricate a monolayer Au coating with complete coverage in controlled fashion. Here we present a facile method to deposit a uniform Au monolayer (ML) film on the [BMIM][PF{sub 6}] ionic liquid substrate using an electrochemical deposition process. It demonstrates that it is feasible to prepare a solid phase coating on the liquid-based substrate. Moreover, the thickness of the monolayer coating can be controlled to a layer-by-layer accuracy.

  9. Transient FTIR spectroscopy for probing reaction pathways on Au catalysts

    Science.gov (United States)

    Overbury, Steven H.

    2008-03-01

    Au is now well known to be an active catalyst if the Au particles are sufficiently small, less than about 5 nm. The causes for this structure sensitivity are now beginning to be better understood. Computational modeling and measurements of size dependence on a single catalyst are consistent with activity at sites with low coordination numbers, due in part to flexibility of adsorbate geometry in these sites. Although small size and low coordinate sites are important in catalyzing, e.g. the CO oxidation reaction, there appear to be other factors which control the observed activity as demonstrated by catalyst deactivation and unusual temperature dependence. We have performed studies of CO oxidation over Au/TiO2, Au/SiO2, Au/ZnO/TiO2 and Au/FePO4 catalysts to explore reaction pathways and the causes for activation and deactivation. Three different reactor systems, a fast gas transient FTIR spectrometer, a slower transient DRIFTS cell and a steady state plug flow reactor have been used to correlate activity with surface species. Using this operando approach the elementary steps in the CO oxidation reaction have been explored. Striking differences between the supports are found. The effect of various pre-treatments, the evolution of the surface species during ``steady state'' reaction and the role of carbonate, oxygen storage, water, hydroxyl upon catalyst activation and deactivation have been explored and will be described. Reaction pathways and mechanisms will be proposed and compared for the different catalysts.

  10. Biosupported Bimetallic Pd Au Nanocatalysts for Dechlorination of Environmental Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    De Corte, S.; Fitts, J.; Hennebel, T.; Sabbe, T.; Bliznuk, V.; Verschuere, S.; van der Lelie, D.; Verstraete, W.; Boon, N.

    2011-08-30

    Biologically produced monometallic palladium nanoparticles (bio-Pd) have been shown to catalyze the dehalogenation of environmental contaminants, but fail to efficiently catalyze the degradation of other important recalcitrant halogenated compounds. This study represents the first report of biologically produced bimetallic Pd/Au nanoparticle catalysts. The obtained catalysts were tested for the dechlorination of diclofenac and trichloroethylene. When aqueous bivalent Pd(II) and trivalent Au(III) ions were both added to concentrations of 50 mg L{sup -1} and reduced simultaneously by Shewanella oneidensis in the presence of H{sub 2}, the resulting cell-associated bimetallic nanoparticles (bio-Pd/Au) were able to dehalogenate 78% of the initially added diclofenac after 24 h; in comparison, no dehalogenation was observed using monometallic bio-Pd or bio-Au. Other catalyst-synthesis strategies did not show improved dehalogenation of TCE and diclofenac compared with bio-Pd. Synchrotron-based X-ray diffraction, (scanning) transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the simultaneous reduction of Pd and Au supported on cells of S. oneidensis resulted in the formation of a unique bimetallic crystalline structure. This study demonstrates that the catalytic activity and functionality of possibly environmentally more benign biosupported Pd-catalysts can be improved by coprecipitation with Au.

  11. Spin Polarization and Quantum Spins in Au Nanoparticles

    Directory of Open Access Journals (Sweden)

    Wen-Hsien Li

    2013-08-01

    Full Text Available The present study focuses on investigating the magnetic properties and the critical particle size for developing sizable spontaneous magnetic moment of bare Au nanoparticles. Seven sets of bare Au nanoparticle assemblies, with diameters from 3.5 to 17.5 nm, were fabricated with the gas condensation method. Line profiles of the X-ray diffraction peaks were used to determine the mean particle diameters and size distributions of the nanoparticle assemblies. The magnetization curves M(Ha reveal Langevin field profiles. Magnetic hysteresis was clearly revealed in the low field regime even at 300 K. Contributions to the magnetization from different size particles in the nanoparticle assemblies were considered when analyzing the M(Ha curves. The results show that the maximum particle moment will appear in 2.4 nm Au particles. A similar result of the maximum saturation magnetization appearing in 2.3 nm Au particles is also concluded through analysis of the dependency of the saturation magnetization MP on particle size. The MP(d curve departs significantly from the 1/d dependence, but can be described by a log-normal function. Magnetization can be barely detected for Au particles larger than 27 nm. Magnetic field induced Zeeman magnetization from the quantum confined Kubo gap opening appears in Au nanoparticles smaller than 9.5 nm in diameter.

  12. Au/Fe/Au multilayer transducers for magneto-optic surface plasmon resonance sensing

    Science.gov (United States)

    Regatos, D.; Fariña, D.; Calle, A.; Cebollada, A.; Sepúlveda, B.; Armelles, G.; Lechuga, L. M.

    2010-09-01

    In this paper, we analyze the magnetoplasmonic (MP) features and sensing capabilities of Au/Fe/Au trilayer structures, as transducers of the magneto-optic surface plasmon resonance (MOSPR) biosensor. This biosensor, which can surpass the sensitivity of the standard SPR sensor, is based on a MP modulation technique generated by the simultaneous stimulation of the surface plasmon polaritons (SPP) and the transversal magneto-optical Kerr effect (TMOKE). We study the magneto-optical activity of the trilayers as a function of the thickness and position of the Fe layer. We first demonstrate that this kind of structure allows modulating the SPP through an external magnetic field and moreover, induce a strong enhancement of the TMOKE effect. The modulation of the SPP is linearly proportional to the thickness of Fe layer and inversely proportional to the distance between the Fe layer and the external dielectric medium. Finally, we experimentally confirm a twofold increase in the MOSPR sensitivity with respect to the intensity-interrogated SPR biosensor in bulk refractive-index changes, keeping a similar chemical resistance and stability, unprecedented in other MP transducers, and biofunctionalization protocols.

  13. Multi-spacecraft observations of ICMEs propagating from 1 AU to 1.5 AU

    Science.gov (United States)

    Guo, J.; von Forstner, J.; Wimmer-Schweingruber, R. F.; Hassler, D.; Zeitlin, C. J.; Ehresmann, B.; Lohf, H.; Appel, J. K.; Heber, B.; Steigies, C. T.; Jian, L.

    2016-12-01

    The Radiation Assessment Detector (RAD) instrument on the Curiosity rover (Mars Science Laboratory mission) has been measuring galactic cosmic rays on the surface of Mars since its landing 4 years ago. Using this data, we can detect Forbush decreases caused by ICMEs passing Mars. To gain a better understanding of the propagation of individual ICMEs from 1 AU (Earth orbit) to 1.5 AU (Mars orbit), we investigate events that took place close to the oppositions of Earth (as well as STEREO A and B) and Mars, i.e., when they were nearly in a straight line on the same side of the Sun in the ecliptic plane. Such lineups allow us to estimate the ICMEs' transit time by estimating the delay time of the corresponding Forbush decreases between data from Earth's orbit (such as neutron monitors on Earth and HEP on both STEREOs) and Mars (RAD). Based on the radial distance between the two measurement locations, the ambient solar wind speeds and the properties of these ICMEs determined in previous studies, we investigate the evolution of the ICME's speed and/or shape during its propagation in the interplanetary medium beyond Earth orbit.

  14. Thermodynamical features of multifragmentation in peripheral Au + Au collisions at 35 A MeV

    Science.gov (United States)

    D'Agostino, M.; Botvina, A. S.; Bruno, M.; Bonasera, A.; Bondorf, J. P.; Bougault, R.; Désesquelles, P.; Geraci, E.; Gulminelli, F.; Iori, I.; Le Neindre, N.; Margagliotti, G. V.; Mishustin, I. N.; Moroni, A.; Pagano, A.; Vannini, G.

    1999-04-01

    The distribution of fragments produced in events involving the multifragmentation of excited sources is studied for peripheral Au + Au reactions at 35 A MeV. The Quasi-Projectile has been reconstructed from its de-excitation products. An isotropic emission in its rest frame has been observed, indicating that an equilibrated system has been formed. The excitation energy of the Quasi-Projectile has been determined via calorimetry. A new event by event effective thermometer is proposed based on the energy balance. A peak in the energy fluctuations is observed related to the heat capacity suggesting that the system undergoes a liquid-gas type phase transition at an excitation energy ˜ 5 A MeV and a temperature 4-6 MeV, dependent on the freeze-out hypothesis. By analyzing different regions of the Campiplot, the events associated with the liquid and gas phases as well as the critical region are thermodynamically characterized. The critical exponents, τ, β, γ, extracted from the high moments of the charge distribution are consistent with a liquid-gas type phase transition.

  15. Dielectron production in Au$+$Au collisions at $\\sqrt{s_{NN}}$=200 GeV

    CERN Document Server

    Adare, A; Ajitanand, N N; Akiba, Y; Akimoto, R; Alexander, J; Alfred, M; Al-Ta'ani, H; Angerami, A; Aoki, K; Apadula, N; Aramaki, Y; Asano, H; Aschenauer, E C; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Bandara, N S; Bannier, B; Barish, K N; Bassalleck, B; Bathe, S; Baublis, V; Baumgart, S; Bazilevsky, A; Beaumier, M; Beckman, S; Belmont, R; Berdnikov, A; Berdnikov, Y; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Bryslawskyj, J; Buesching, H; Bumazhnov, V; Butsyk, S; Campbell, S; Castera, P; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choi, S; Choudhury, R K; Christiansen, P; Chujo, T; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Csanád, M; Csörgő, T; Dairaku, S; Danley, D; Datta, A; Daugherity, M S; David, G; DeBlasio, K; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Ding, L; Dion, A; Diss, P B; Do, J H; Donadelli, M; D'Orazio, L; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Edwards, S; Efremenko, Y V; Engelmore, T; Enokizono, A; Esumi, S; Eyser, K O; Fadem, B; Feege, N; Fields, D E; Finger, M; Jr., \\,; Fleuret, F; Fokin, S L; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fusayasu, T; Gainey, K; Gal, C; Gallus, P; Garg, P; Garishvili, A; Garishvili, I; Ge, H; Giordano, F; Glenn, A; Gong, X; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Gunji, T; Guo, L; Gustafsson, H -Å; Hachiya, T; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamilton, H F; Han, S Y; Hanks, J; Hasegawa, S; Haseler, T O S; Hashimoto, K; Haslum, E; Hayano, R; He, X; Hemmick, T K; Hester, T; Hill, J C; Hollis, R S; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hoshino, T; Hotvedt, N; Huang, J; Huang, S; Ichihara, T; Iinuma, H; Ikeda, Y; Imai, K; Imrek, J; Inaba, M; Iordanova, A; Isenhower, D; Issah, M; Ivanishchev, D; Jacak, B V; Javani, M; Jezghani, M; Jia, J; Jiang, X; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kamin, J; Kanda, S; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kazantsev, A V; Kempel, T; Key, J A; Khachatryan, V; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, C; Kim, D J; Kim, E -J; Kim, G W; Kim, H J; Kim, K -B; Kim, M; Kim, Y -J; Kim, Y K; Kimelman, B; Kinney, E; Kiss, Á; Kistenev, E; Kitamura, R; Klatsky, J; Kleinjan, D; Kline, P; Koblesky, T; Komatsu, Y; Komkov, B; Koster, J; Kotchetkov, D; Kotov, D; Král, A; Krizek, F; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, B; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Leitgab, M; Lewis, B; Li, X; Lim, S H; Levy, L A Linden; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Makek, M; Manion, A; Manko, V I; Mannel, E; Masumoto, S; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Meles, A; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Milov, A; Mishra, D K; Mitchell, J T; Miyachi, Y; Miyasaka, S; Mizuno, S; Mohanty, A K; Mohapatra, S; Montuenga, P; Moon, H J; Moon, T; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Mwai, A; Nagae, T; Nagamiya, S; Nagashima, K; Nagle, J L; Nagy, M I; Nakagawa, I; Nakagomi, H; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nattrass, C; Nederlof, A; Netrakanti, P K; Nihashi, M; Niida, T; Nishimura, S; Nouicer, R; Novak, T; Novitzky, N; Nyanin, A S; O'Brien, E; Ogilvie, C A; Okada, K; Koop, J D Orjuela; Osborn, J D; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, J S; Park, S; Park, S K; Pate, S F; Patel, L; Patel, M; Pei, H; Peng, J -C; Pereira, H; Perepelitsa, D V; Perera, G D N; Peressounko, D Yu; Perry, J; Petti, R; Pinkenburg, C; Pinson, R; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ramson, B J; Ravinovich, I; Read, K F; Reynolds, D; Riabov, V; Riabov, Y; Richardson, E; Rinn, T; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rowan, Z; Rubin, J G; Sahlmueller, B; Saito, N; Sakaguchi, T; Sako, H; Samsonov, V; Sano, M; Sarsour, M; Sato, S; Sawada, S; Schaefer, B; Schmoll, B K; Sedgwick, K; Seidl, R; Sen, A; Seto, R; Sett, P; Sexton, A; Sharma, D; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Snowball, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sukhanov, A; Sumita, T; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Tieulent, R; Timilsina, A; Todoroki, T; Tomášek, L; Tomášek, M; Torii, H; Towell, C L; Towell, R; Towell, R S; Tserruya, I; Tsuchimoto, Y; Tsuji, T; Vale, C; van Hecke, H W; Vargyas, M; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; White, A S; White, S N; Winter, D; Wolin, S; Woody, C L; Wysocki, M; Xia, B; Xue, L; Yalcin, S; Yamaguchi, Y L; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; Yoo, J H; Yoon, I; You, Z; Younus, I; Yu, H; Yushmanov, I E; Zajc, W A; Zelenski, A; Zhou, S; Zou, L

    2015-01-01

    We present measurements of $e^+e^-$ production at midrapidity in Au$+$Au collisions at $\\sqrt{s_{_{NN}}}$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($m_{ee} <$ 5 GeV/$c^2$) and pair transverse momentum ($p_T$ $<$ 5 GeV/$c$), for minimum bias and for five centrality classes. The \\ee yield is compared to the expectations from known sources. In the low-mass region ($m_{ee}=0.30$--0.76 GeV/$c^2$) there is an enhancement that increases with centrality and is distributed over the entire pair \\pt range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $2.3\\pm0.4({\\rm stat})\\pm0.4({\\rm syst})\\pm0.2^{\\rm model}$ or to $1.7\\pm0.3({\\rm stat})\\pm0.3({\\rm syst})\\pm0.2^{\\rm model}$ for minimum bias collisions when the open-heavy-flavor contribution is calculated with {\\sc pythia} or {\\sc mc@nlo}, respectively. The inclusive mass and $p_T$ distributions as well as the centrality dependence are well repr...

  16. Electrochemical Investigations of 4-Methoxypyridine Adsorption on Au(111) Predict Its Suitability for Stabilizing Au Nanoparticles.

    Science.gov (United States)

    Unni, Bipinlal; Simon, Sajna; Burgess, Ian J

    2015-09-15

    A thermodynamic analysis of the adsorption of 4-methoxypyridine (MOP) on Au(111) surfaces is presented in an effort to determine its propensity to stabilize metal nanoparticles. The adsorption of MOP is compared and contrasted to the adsorption of 4-dimethylaminopyridine (DMAP), the latter of which is well-known to form stable Au nanoparticles. Electrochemical studies show that MOP, like most pyridine derivatives, can exhibit two different adsorption states. The electrical state of the metal, the pH of the solution, and the surface crystallography determine whether MOP adopts a low-coverage, π-bonded orientation or a high-coverage, σ-type orientation. A modified Langmuir adsorption isotherm is used to extract free energies of adsorption which are roughly 10% stronger for DMAP compared to MOP at equivalent conditions when expressed on a rational basis. The higher adsorption strength is attributed to DMAP's greater Lewis basicity. Qualitatively, MOP and DMAP adsorption are found to be completely analogous, implying that MOP-protected gold particles should be stable under conditions that favor the high-coverage adsorption state. Using a previously reported, single-phase synthesis, this is shown to be the case.

  17. Azimuthal Anisotropy in U+U and Au+Au Collisions at RHIC.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandin, A V; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Cervantes, M C; Chakaberia, I; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, H Z; Huang, B; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, W; Li, Y; Li, C; Li, Z M; Li, X; Li, X; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, L; Ma, R; Ma, Y G; Ma, G L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; Meehan, K; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V; Olvitt, D L; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Peterson, A; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Sharma, M K; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Skoby, M J; Smirnov, D; Smirnov, N; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B J; Sun, X; Sun, X M; Sun, Z; Sun, Y; Surrow, B; Svirida, D N; Szelezniak, M A; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A N; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Trzeciak, B A; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbaek, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, Y; Wang, H; Wang, J S; Wang, Y; Wang, G; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, Y F; Xu, N; Xu, Z; Xu, Q H; Xu, H; Yang, Y; Yang, Y; Yang, C; Yang, S; Yang, Q; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, J B; Zhang, J; Zhang, Z; Zhang, S; Zhang, Y; Zhang, J L; Zhao, F; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2015-11-27

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v_{2}{2} and v_{2}{4}, for charged hadrons from U+U collisions at sqrt[s_{NN}]=193  GeV and Au+Au collisions at sqrt[s_{NN}]=200  GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v_{2}{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. We also show that v_{2} vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  18. Bimodality in binary Au + Au collisions from 60 to 100 MeV/u

    Energy Technology Data Exchange (ETDEWEB)

    Pichon, M.; Tamain, B.; Bougault, R. [Caen Univ., Lab. de Physique Corpusculaire, IN2P3-CNRS, ISMRA, 14 (France)] [and others

    2003-03-01

    The deexcitation of quasi-projectiles (QP) released in binary Au on Au collisions as been studied from 60 to 100 MeV/u. Bimodality between two different decay patterns has been observed for intermediate violence collisions. The main experimental result is that the system jumps from one mode to the other on a narrow range of energy deposit and/or impact parameter. The sorting of the events (according to the violence of the collision) has been provided by the perpendicular energy of the light charged particles emitted on the quasi-target side. Such a sorting prevents spurious autocorrelation effects between the sorting variable and the observed mechanism. The two modes of the QP decay correspond on the one side to residue or fission fragments production, and on the other side to the multifragmentation channel. A detailed study has been performed in order to try to establish the origin of the observed bimodality in disentangling dynamical or geometrical effects from bulk matter properties linked with a liquid-gas type phase transition. The whole set of data is coherent with a dominant role of the deposited excitation energy as it is expected from theoretical arguments.(lattice gas model) in the framework of a liquid-gas phase transition picture. (authors)

  19. Influence of Bottom Quark Jet Quenching on Single ElectronTomography of Au+Au

    Energy Technology Data Exchange (ETDEWEB)

    Djordjevic, Magdalena; Gyulassy, Miklos; Vogt, Ramona; Wicks, Simon

    2005-07-12

    High transverse momentum single (non-photonic) electrons are shown to be sensitive to the stopping power of both bottom, b, and charm, c, quarks in AA collisions. We apply the DGLV theory of radiative energy loss to predict c and b quark jet quenching and compare the FONLL and PYTHIA heavy flavor fragmentation and decay schemes. We show that single electrons in the p{sub T} = 5-10 GeV range are dominated by the decay of b quarks rather than the more strongly quenched c quarks in Au+Au collisions at {radical}s = 200 AGeV. The smaller b quark energy loss, even for extreme opacities with gluon rapidity densities up to 3500, is predicted to limit the nuclear modification factor, R{sub AA}, of single electrons to the range R{sub AA} {approx} 0.5-0.6, in contrast to previous predictions of R{sub AA} {le} 0.2-0.3 based on taking only c quark jet fragmentation into account.

  20. PHENIX results on low-mass dileptons in Au + Au collisions with the Hadron Blind Detector

    Science.gov (United States)

    Makek, M.

    2016-12-01

    We present e+e- continuum measurement in Au+Au collisions at √{sNN} = 200 GeV from the RHIC 2010 run with the Hadron Blind Detector upgrade of PHENIX. The measurement reaches a high purity of the electron sample of ≥ 95% at all centralities and provides an excellent qualitative and quantitative understanding of the background. The e+e- invariant yields show an enhancement in the low-mass region (mee = 0.30 - 0.76 GeV /c2) compared to the expectations from hadronic sources, but not as large as the one previously reported by PHENIX. The observed excess is well reproduced by models incorporating the broadening of the ρ meson due to scattering off baryons in the hot hadronic gas. The measured invariant yields in the intermediate-mass region (mee = 1.2 - 2.8 GeV /c2) leave room for additional sources when compared to the cocktail dominated by the semileptonic decays of heavy flavor mesons.

  1. Measurement of Direct Photons in Ultra-Relativistic Au+Au Collisions

    Science.gov (United States)

    Gong, Haijiang

    Direct photons provide a tool to study the different stages of a heavy ion collision, especially the formation of the quark-gluon-plasma (QGP), without being influenced by the strong reaction and hadronization processes. The yield of direct photons can be determined from the inclusive photon yield and the photon yield from hadronic decays. At low pT, where a significant fraction of direct photon is expected to come from the thermalized medium of deconfined quarks and gluons and interacting hadrons, the measurement is very challenging. These so-called thermal photons carry information about the initial temperature of the medium. We present a new analysis technique that was developed to improve direct photon production measurement in the low and medium pT range. The technique was applied to the PHENIX Run4 Au+Au sqrt(sNN)=200GeV/c collisions dataset. It uses strict particle identification (PID) in the Electromagnetic Calorimeter (EMCal) and a charged particle veto to extract a clean photon signal. These photons are then tagged with EMCal photon candidates with loose PID cuts, which can be reconstructed with high efficiency, to determine the fraction of photons originating from neutral pion decays. Most systematic uncertainties and detector effects cancel in this method. The results are compared with recent PHENIX direct photon measurement through external conversion method and theoretical calculation predicting thermal photon production.

  2. Synthesis of Au/C and Au/Pani for anode electrodes in glucose microfluidic fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Balcazar, M.; Morales-Acosta, D.; Castaneda, F.; Arriaga, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, 76703 Queretaro (Mexico); Ledesma-Garcia, J. [Division de Investigacion y Posgrado, Facultad de Ingenieria, Universidad Autonoma de Queretaro, 76010 Queretaro (Mexico)

    2010-06-15

    Gold nanoparticles have been prepared by two methods: chemical (ex-situ, Au/C) by two phase protocol, and electrochemical (in-situ, Au/Pani) by electroreduction of gold ions on a polyaniline film and compared as anode catalysts in a glucose microfluidic fuel cell. In this paper the structural characteristics and electrocatalytic properties were investigated by X-ray diffraction and electrochemical measurements. The catalytic behavior of both anodes was tested in a microfluidic fuel cell with a reference electrode incorporated, by means of linear sweep voltammetry (LSV), showing a cathodic shift in the glucose oxidation peak for Au/Pani. Results show a higher power density (0.5 mW cm{sup -} {sup 2}) for Au/C anode compared with an already reported value, where a glucose microfluidic fuel cell was used in similar conditions. (author)

  3. Wetting - Dewetting Transitions of Au/Ni Bilayer Films

    Science.gov (United States)

    Cen, Xi

    Thin films deposited at low temperatures are often kinetically constrained and will dewet the underlying substrate when annealed. Solid state dewetting is driven by the minimization of the total free energy of thin film-substrate interface and free surface, and mostly occurs through surface diffusion. Dewetting is a serious concern in microelectronics reliability. However, it can also be utilized for the self-assembly of nanostructures with potentials in storage, catalysis, or transistors. Therefore, a fundamental understanding of the dewetting behavior of thin metal films is critical for improving the thermal stability of microelectronics and controlling the order of self-assembled nanostructures. Mechanisms for dewetting of single layer films have been studied extensively. However little work has been reported on multilayer or alloyed thin films. In the thesis, the solid state dewetting of Au/Ni bilayer films deposited on SiO2/Si substrates was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and aberration corrected scanning TEM (STEM). Ex-situ SEM and TEM studies were performed with in-situ TEM heating characterization to identify the mechanisms during the dewetting process of Au/Ni bilayer films. The solid state dewetting of Au/Ni bilayer films from SiO2/Si substrates exhibits both homogeneous and localized dewetting of Ni and long-edge retraction for Au under isothermal annealing condition. The top Au layer retracts up to 1 mm from the edge of the substrate wafer to reduce the energetically unfavored Au/Ni interface. In contrast, Ni dewets and agglomerates locally due to its limited diffusivity compared to Au. Film morphology and local chemical composition varies significantly across hundreds of microns along the direction normal to the retracting edge. Besides long range edge receding, localized dewetting shows significant changes in film morphology and chemical distribution. Both Au and Ni shows texturing. Despite

  4. Proton-Λ correlations in central Au+Au collisions at VsNN=200 GeV

    NARCIS (Netherlands)

    Bai, Y.; Botje, M.A.J.|info:eu-repo/dai/nl/070139032; Grebenyuk, O.|info:eu-repo/dai/nl/304848883; Mischke, A.|info:eu-repo/dai/nl/325781435; Peitzmann, T.|info:eu-repo/dai/nl/304833959; Russcher, M.J.|info:eu-repo/dai/nl/304847844; Snellings, R.J.M.|info:eu-repo/dai/nl/165585781; van der Kolk, N.

    2006-01-01

    We report on p-Λ,p-Λ̅ ,p̅ -Λ, and p̅ -Λ̅ correlation functions constructed in central Au-Au collisions at √sNN=200 GeV by the STAR experiment at RHIC. The proton and lambda source size is inferred from the p-Λ and p̅ -Λ̅ correlation functions. It is found to be smaller than the pion source size also

  5. Partonic flow and ϕ-meson production in Au+Au collisions at VsNN=200 = GeV

    NARCIS (Netherlands)

    Bai, Y.; Benedosso, F.; Botje, M.A.J.; Grebenyuk, O.; Mischke, A.; Peitzmann, T.; Russcher, M.J.; Snellings, R.J.M.; van der Kolk, N.

    2007-01-01

    We present first measurements of the ϕ-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from √sNN=200  GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the ϕ meson is consistent with the trend observed for mesons. The ratio of the yields

  6. Unique Properties of Core Shell Ag@Au Nanoparticles for the Aptasensing of Bacterial Cells

    OpenAIRE

    Ezat Hamidi-Asl; Freddy Dardenne; Sanaz Pilehvar; Ronny Blust; Karolien De Wael

    2016-01-01

    In this article, it is shown that the efficiency of an electrochemical aptasensing device is influenced by the use of different nanoparticles (NPs) such as gold nanoparticles (Au), silver nanoparticles (Ag), hollow gold nanospheres (HGN), hollow silver nanospheres (HSN), silver–gold core shell (Ag@Au), gold–silver core shell (Au@Ag), and silver–gold alloy nanoparticles (Ag/Au). Among these nanomaterials, Ag@Au core shell NPs are advantageous for aptasensing applications because the core impro...

  7. Amperometric Immunosensor for Carbofuran Detection Based on MWCNTs/GS-PEI-Au and AuNPs-Antibody Conjugate

    Directory of Open Access Journals (Sweden)

    Xiangyou Wang

    2013-04-01

    Full Text Available In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au nanocomposites were modified onto the surface of a glass carbon electrode (GCE via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD, ultraviolet and visible absorption spectroscopy (UV-vis and scanning electron microscopy (SEM, respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3. The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.

  8. Au crystal growth on natural occurring Au-Ag aggregate elucidated by means of precession electron diffraction (PED)

    Science.gov (United States)

    Roqué Rosell, Josep; Portillo Serra, Joaquim; Aiglsperger, Thomas; Plana-Ruiz, Sergi; Trifonov, Trifon; Proenza, Joaquín A.

    2018-02-01

    In the present work, a lamella from an Au-Ag aggregate found in Ni-laterites has been examined using Transmission Electron Microscope to produce a series of Precision Electron Diffraction (PED) patterns. The analysis of the structural data obtained, coupled with Energy Dispersive X-ray microanalysis, made it possible to determine the orientation of twinned native gold growing on the Au-Ag aggregate. The native Au crystal domains are found to have grown at the outermost part of the aggregate whereas the inner core of the aggregate is an Au-Ag alloy (∼4 wt% Ag). The submicron structural study of the natural occurring Au aggregate points to the mobilization and precipitation of gold in laterites and provides insights on Au aggregates development at supergene conditions. This manuscript demonstrates the great potential of electron crystallographic analysis, and in particular, PED to study submicron structural features of micron sized mineral aggregates by using the example of a gold grain found in a Ni-laterite deposits.

  9. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    Science.gov (United States)

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-05-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction time. The results indicated that metallic Au0 exhibits considerable catalytic activity and that Au nano-particle aggregation may be another reason for the AuCl3/AC catalytic activity in acetylene hydrochlorination.

  10. Jet-hadron correlations in √[s(NN)]=200  GeV p+p and central Au+Au collisions.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-03-28

    Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at √[s(NN)]=200  GeV in STAR are presented. The trigger jet population in Au+Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.

  11. First-principles study of the binary intermetallics in the Au-Rb system

    Science.gov (United States)

    Benmechri, Achraf; Djaballah, Yassine; Amer, Ahmed Said; Belgacem-Bouzida, Aissa; Bouderba, Hichem

    2014-06-01

    First-principles calculations within density functional theory (DFT) with the projector augmented wave (PAW) technique were used to investigate the stabilities of intermetallics in the Au-Rb system at 0 K. Four intermetallics: Au7Rb3, Au3Rb2, Au5Rb and AuRb were investigated in their observed experimental structures. The Au2Rb compound, reported in the Au-Rb phase diagrams without specifying explicitly its structure, was also investigated by inspecting several hypothetical structures. A suspect compound (AuRb2) was also investigated. Results show that: (i) The Au3Rb2 and Au7Rb3 compounds, which were never reported in any Au-Rb phase diagram, are stable at 0 K. (ii) The Au2Rb compound is not a ground state for all the tested structures. (iii) Stability of the Au5Rb and AuRb compounds was confirmed. (iv) The new compound AuRb2, not yet reported experimentally, is found mechanically stable at 0 K.

  12. Thiol ligand-induced transformation of Au38(SC2H4Ph)24 to Au36(SPh-t-Bu)24.

    Science.gov (United States)

    Zeng, Chenjie; Liu, Chunyan; Pei, Yong; Jin, Rongchao

    2013-07-23

    We report a disproportionation mechanism identified in the transformation of rod-like biicosahedral Au38(SCH2CH2Ph)24 to tetrahedral Au36(TBBT)24 nanoclusters. Time-dependent mass spectrometry and optical spectroscopy analyses unambiguously map out the detailed size-conversion pathway. The ligand exchange of Au38(SCH2CH2Ph)24 with bulkier 4-tert-butylbenzenethiol (TBBT) until a certain extent starts to trigger structural distortion of the initial biicosahedral Au38(SCH2CH2Ph)24 structure, leading to the release of two Au atoms and eventually the Au36(TBBT)24 nanocluster with a tetrahedral structure, in which process the number of ligands is interestingly preserved. The other product of the disproportionation process, i.e., Au40(TBBT)m+2(SCH2CH2Ph)24-m, was concurrently observed as an intermediate, which was the result of addition of two Au atoms and two TBBT ligands to Au38(TBBT)m(SCH2CH2Ph)24-m. The reaction kinetics on the Au38(SCH2CH2Ph)24 to Au36(TBBT)24 conversion process was also performed, and the activation energies of the structural distortion and disproportionation steps were estimated to be 76 and 94 kJ/mol, respectively. The optical absorption features of Au36(TBBT)24 are interpreted on the basis of density functional theory simulations.

  13. Au3+/Au0 Supported on Chromium(III Terephthalate Metal Organic Framework (MIL-101 as an Efficient Heterogeneous Catalystfor Three-Component Coupling Synthesis of Propargylamines

    Directory of Open Access Journals (Sweden)

    Lili Liu

    2017-01-01

    Full Text Available Post-synthesis modification is a useful method for the functionalization of metal–organic frameworks (MOFs. A novel catalyst Au@MIL-101-ED-SA (ED = ethylenediamine, SA = salicylaldehyde, containing coexisting Au3+ ions and Au0 nanoparticles, was prepared successfully by post-synthesis modification with ethylenediamine, salicylaldehyde and gold. Gold nanoparticles supported on MIL-101 (Au@MIL-101 were prepared successfully by the impregnation method. Au@MIL-101-ED-SA and Au@MIL-101 were characterized by N2 adsorption–desorption, X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and inductively coupled plasma-optical emission spectrometry. Au@MIL-101-ED-SA and Au@MIL-101 were applied as environmentally friendly catalysts in the three-component coupling reaction of aldehydes, amines, and alkynes for the preparation of diverse propargylamines. Au@MIL-101-ED-SA contained a fraction of cationic gold (Au3+/Au0 = 0.9 and showed higher catalytic activity than Au@MIL-101, which was prepared by the impregnation method. Furthermore, the reactions were performed under heterogeneous conditions and the novel catalyst was successfully recycled for four consecutive runs.

  14. Au rendez-vous allemand (2

    Directory of Open Access Journals (Sweden)

    Agnès Bouvier

    2010-12-01

    Full Text Available La parution en 1857 des Études d’histoire religieuse d’Ernest Renan marque l’entrée en France des conceptions allemandes du mythe appliquées à l’histoire des textes sacrés. Or, cette date est aussi celle de la rencontre intellectuelle entre Renan et Flaubert, rencontre qui se matérialisera deux ans plus tard : au moment où Flaubert entreprend Salammbô, il accède aux travaux philologiques de la « nouvelle école » représentée en France par Renan. La supériorité de l’école allemande tient essentiellement selon Renan à sa capacité de penser le mythe comme un tout « indivis » irréductible à toute interprétation univoque : en dépit de certaines outrances des « rationalistes » et des « mythologues », dont il distingue nettement les deux types d’approche, Renan envisage l’exégèse allemande comme un progrès dont il montre les étapes et qu’il se propose d’achever en développant ce qu’il appelle une critique « sympathique ». Davantage qu’une méthode, il définit une posture critique d’adhésion à l’objet que Flaubert pourra mettre en oeuvre dans son roman.The publication in 1857 of Ernest Renan’s Études d’histoire religieuse signals the introduction in France of German ideas about myths applied to the history of religious texts. Now this date is also that of the intellectual encounter between Renan and Flaubert. Their actual meeting came about two years later. Indeed, while Flaubert was starting Salammbô, he discovered the philological studies of the “New School” represented in France by Renan. According to Renan the superiority of the German School was due to its capacity to comprehend the myth as an undivided whole irreducible to a univocal interpretation. Thus, despite the excesses of the “rationalists” and “mythologs”, whose methods he clearly distinguished, Renan considered the German exegesis a progress. He outlined its stages which he sought to complete by

  15. Structure investigation of organic molecules on Au(111) surfaces; Strukturuntersuchung organischer Molekuele auf Au(111)-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kazempoor, Michel

    2009-02-02

    The present work covers two topics namely the coadsorption of formic acid and water on Au(111) and the structure of biphenylalkanthiole SAMs on Au(111) surfaces. The coadsorption of formic acid and water on Au(111) surfaces has been investigated by means of vibrational and photoelectron spectroscopy (HREELS, XPS). Formic acid adsorbs at 90 K molecularly with vibrational modes characteristic for flat lying zig-zag chains in the mono- and multilayer regime, like in solid formic acid. The structure of the flat lying formic acid chains was determined by low energy electron diffraction (LEED) as a (2r3 x r19) unit cell. Annealing results in a complete desorption at 190 K. Sequential adsorption of formic acid and water at 90 K shows no significant chemical interaction. Upon annealing the coadsorbed layer to 140 K a hydrogenbonded cyclic complex of formic acid with one water molecule could be identified using isotopically labelled adsorbates. Upon further annealing this complex decomposes leaving molecularly adsorbed formic acid on the surface at 160 K, accompanied by a proton exchange between formic acid and water. The influence of the alkane spacer chain length on the structure of biphenylalkanethiols on Au(111) surfaces was investigated as well. A systematic study was done on BPn-SAMs deposited from the gas phase. For every chain length a structure was found by LEED. Furthermore the influence of temperature on the structure was investigated in the range from room temperature up to about 400 K. To obviate influences from different preparation methods BP3 and BP4 was deposited from gas phase and from solution. No LEED spots were observed on BP4 SAMs deposited from solution. For BP3 an influence of the preparation could be excluded. For all BPn-SAMs a good agreement between LEED and STM data's was found. Nevertheless different unit cells were determined by LEED and STM consistent structures could be suggested considering the unit cell size given by LEED and the

  16. Gestion des ressources minérales et conflits au Mali et au Niger

    OpenAIRE

    Deltenre, Damien

    2012-01-01

    Les ressources minérales représentent des secteurs importants des économies du Mali (or) et du Niger (uranium et pétrole). Dans le contexte incertain qui suit la crise libyenne de 2011 et l’effondrement du Mali début 2012, il convient d’étudier dans quelle mesure les richesses naturelles de ces deux pays possèdent un potentiel de prévention ou d’aggravation des conflits. La gestion malienne et nigérienne des ressources naturelles est examinée au départ d’un cadre analytique centré sur les not...

  17. Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands

    Science.gov (United States)

    Grigg, R.W.; Grossman, E.E.; Earle, S.A.; Gittings, S.R.; Lott, D.; McDonough, J.

    2002-01-01

    During the last glacial maximum (LGM), about 21,000 years ago, the Hawaiian Islands of Maui, Lanai, and Molokai were interconnected by limestone bridges, creating a super-island known as Maui-Nui. Approximately 120 m of sea-level rise during the Holocene Transgression flooded, and then drowned, these bridges separating the islands by inter-island channels. A new multibeam high-resolution bathymetric survey of the channels between the islands, coupled with observations and video-transects utilizing DeepWorker-2000 submersibles, has revealed the existence of numerous drowned reef features including concentric solution basins, solution ridges (rims), sand and sediment plains, and conical-shaped reef pinnacles. The concentric basins contain flat lagoon-like bottoms that are rimmed by steep-sided limestone walls. Undercut notches rim the basins at several depths, marking either sea-level still stands or paleo-lake levels. All of the solution basins shallower than 120 m were subaerial at the LGM, and at one stage or another may have been shallow shoreline lakes. Today, about 70 drowned reef pinnacles are scattered across the Maui-Lanai underwater bridge and all are situated in wave-sheltered positions. Most drowned during the interval between 14,000 and 10,000 years ago when sea-level rise averaged 15 mm/year. Virtually all of the surficial topography in the Au'au Channel today is a product of karst processes accentuated by marginal reef growth during the Holocene. Both the submerged basins and the drowned reefs represent an archive of sea-level and climate history in Hawaii during the late Quaternary.

  18. Relégation au village

    Directory of Open Access Journals (Sweden)

    Nicolas Renahy

    2010-12-01

    Full Text Available Les thèses de l’individualisation des sociétés occidentales, ou de l’exclusion de ceux qui resteraient en marge d’une vaste classe moyenne aux modes de vie homogénéisés, ont sans doute permis de sortir d’une grille de lecture rigide héritée du marxisme. Mais elles résistent aujourd’hui mal aux faits et sont vivement contredites par le renouvellement des études sur les inégalités sociales pensées en termes de stratification. Enquêtant la population ouvrière d’un village industriel de Bourgogne au cours des années 1990, l’auteur a pu mesurer tout autant la force socialisatrice continue du groupe ouvrier sur sa jeunesse que le lent processus de délitement de ses cadres de références, longtemps stabilisés autour d’une mono-industrie métallurgique, provoquant une crise dans la reproduction de ce monde ouvrier. C’est cette crise de reproduction qui est évoquée ici. Dans un premier temps sont explicitées les formes passées de la présence industrielle au village, qui n’a jamais été celle d’un bastion de la grande industrie – la population locale n’est pas structurellement différenciée de celle de son environnement rural immédiat. L’exemple d’une lignée familiale d’artisans montre pour finir l’étroit maillage entre usine et structures sociales plus classiquement rurales, favorisant la constitution d’un capital d’autochtonie, déclinaison populaire du capital social.Relegation to the villageArguments demonstrating the individualisation of western societies, or the exclusion of those who stay on the margins of a vast middle class homogeneous life style, have no doubt allowed the move away from the rigid interpretations inherited from Marxism. However, these arguments resist today in spite of the facts and they are even keenly contradicted by the renewal of stratification studies on social inequalities. Analyzing the working population of an industrial village in Bourgogne during the

  19. Synthesis of Au38(SCH2CH2Ph)24, Au36(SPh-tBu)24, and Au30(S-tBu)18 Nanomolecules from a Common Precursor Mixture.

    Science.gov (United States)

    Rambukwella, Milan; Dass, Amala

    2017-10-17

    Phenylethanethiol protected nanomolecules such as Au25, Au38, and Au144 are widely studied by a broad range of scientists in the community, owing primarily to the availability of simple synthetic protocols. However, synthetic methods are not available for other ligands, such as aromatic thiol and bulky ligands, impeding progress. Here we report the facile synthesis of three distinct nanomolecules, Au38(SCH2CH2Ph)24, Au36(SPh-tBu)24, and Au30(S-tBu)18, exclusively, starting from a common Aun(glutathione)m (where n and m are number of gold atoms and glutathiolate ligands) starting material upon reaction with HSCH2CH2Ph, HSPh-tBu, and HStBu, respectively. The systematic synthetic approach involves two steps: (i) synthesis of kinetically controlled Aun(glutathione)m crude nanocluster mixture with 1:4 gold to thiol molar ratio and (ii) thermochemical treatment of the purified nanocluster mixture with excess thiols to obtain thermodynamically stable nanomolecules. Thermochemical reactions with physicochemically different ligands formed highly monodispersed, exclusively three different core-size nanomolecules, suggesting a ligand induced core-size conversion and structural transformation. The purpose of this work is to make available a facile and simple synthetic method for the preparation of Au38(SCH2CH2Ph)24, Au36(SPh-tBu)24, and Au30(S-tBu)18, to nonspecialists and the broader scientific community. The central idea of simple synthetic method was demonstrated with other ligand systems such as cyclopentanethiol (HSC5H9), cyclohexanethiol(HSC6H11), para-methylbenzenethiol(pMBT), 1-pentanethiol(HSC5H11), 1-hexanethiol(HSC6H13), where Au36(SC5H9)24, Au36(SC6H11)24, Au36(pMBT)24, Au38(SC5H11)24, and Au38(SC6H13)24 were obtained, respectively.

  20. New systematic features in the neutron-deficient Au isotopes

    Science.gov (United States)

    Venhart, M.; Wood, J. L.; Sedlák, M.; Balogh, M.; Bírová, M.; Boston, A. J.; Cocolios, T. E.; Harkness-Brennan, L. J.; Herzberg, R.-D.; Holub, L.; Joss, D. T.; Judson, D. S.; Kliman, J.; Klimo, J.; Krupa, L.; Lušnák, J.; Makhathini, L.; Matoušek, V.; Motyčák, Š.; Page, R. D.; Patel, A.; Petrík, K.; Podshibyakin, A. V.; Prajapati, P. M.; Rodin, A. M.; Špaček, A.; Urban, R.; Unsworth, C.; Veselský, M.

    2017-07-01

    A recently developed portable, on-line capability for γ-ray and conversion-electron spectroscopy, HIGH-TATRA is demonstrated with its application to the study of 183Hg \\to 183Au at ISOLDE. Key details of the low-energy level scheme of the neutron-deficient nuclide 183Au populated in this decay are presented. A broad energy germanium detector is employed to achieve this (the first-ever use of such a device in decay-scheme spectroscopy), by way of a combination of high-gain γ-ray singles spectroscopy and γ-γ coincidence spectroscopy. Further, by combining the γ-ray detectors with a liquid-nitrogen-cooled Si(Li) detector operated under high vacuum, conversion-electron singles and e-γ coincidences are obtained. These data lead to the determination of transition multipolarities and the location of a highly converted (E0 + M1 + E2) transition in the 183Au decay scheme, suggesting a possible new shape coexisting structure in this nucleus. Identification of new intruder and normal states fixes their relative energies in 183Au for the first time. New systematic features in the odd-Au isotopes are presented.

  1. Acetanilide mediated reversible assembly and disassembly of Au nanoparticles.

    Science.gov (United States)

    Murugadoss, A; Kar, Manoranjan; Chattopadhyay, Arun

    2008-08-01

    Herein we report the generation of Au nanoparticles (NPs) by sparingly soluble acetanilide in water. We also report the formation of linear chain-like superstructures of self-assembled Au NPs, in the presence of excess acetanilide. This was achieved in two different ways. In the first method, acetanilide was added, with increasing concentration, into aqueous HAuCl(4) to produce Au NPs as well as for the formation of assembly, which varied according to the concentration of acetanilide. The other route involved formation of spherical Au NPs at the lowest concentration of acetanilide, which was followed by the formation of assembly of various lengths upon further addition of variable amount of acetanilide. The assemblies were stable in aqueous solution for days with characteristic UV-vis absorption spectra consisting of two peaks. While the wavelength of the first peak remained the same, the position of the second peak changed to longer wavelength with increasing acetanilide concentration. Interestingly, the linear chain-like arrays could be broken into individual particles by first dilution of the solution concentration followed by treatment with ultrasonic waves. The individual Au NPs again formed linear chain-like arrays upon addition of excess acetanilide.

  2. Exotic high activity surface patterns in PtAu nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2013-05-09

    The structure and chemical ordering of PtAu nanoclusters of 79, 135, and 201 atoms are studied via a combination of a basin hopping atom-exchange technique (to locate the lowest energy homotops at fixed composition), a symmetry orbit technique (to find the high symmetry isomers), and density functional theory local reoptimization (for determining the most stable homotop). The interatomic interactions between Pt and Au are derived from the empirical Gupta potential. The lowest energy structures show a marked tendency toward PtcoreAushell chemical ordering by enrichment of the more cohesive Pt in the core region and of Au in the shell region. We observe a preferential segregation of Pt atoms to (111) facets and Au atoms to (100) facets of the truncated octahedron cluster motif. Exotic surface patterns are obtained particularly for Pt-rich compositions, where Pt atoms are being surrounded by Au atoms. These surface arrangements boost the catalytic activity by creating a large number of active sites. © 2013 American Chemical Society.

  3. L'APPRENTISSAGE AU CERN - French version only

    CERN Document Server

    2003-01-01

    APPRENTISSAGES TECHNIQUES FORMATION ET DEVELOPPEMENT HR/TD/AP L'APPRENTISSAGE AU CERN pour les professions d'électronicien(ne) et de laborantin(e) en physique L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 7 places au total sont ouvertes au recrutement pour les deux professions. L'apprentissage dure 4 ans. Minima requis pour faire acte de candidature : - avoir terminé la scolarité obligatoire - être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne, Finlande, France, Grèce, Hongrie, Italie, Norvège, Pays-Bas, Pologne, Portugal, République slovaque, République tchèque, Royaume-Uni, Suède, Suisse) - avoir au moins 15 ans et moins de 21 ans à la date de début de l'apprentissage - avoir un niveau scolaire correspondant à la 9ème générale ou moderne...

  4. Formation of Au nanoparticle arrays on hydrogel two-dimensional patterns based on poly(vinylpyrrolidone)

    Science.gov (United States)

    Tsukuda, Satoshi; Okamoto, Kazumasa; Yamamoto, Hiroki; Kozawa, Takahiro; Omata, Takahisa

    2017-06-01

    In this study, we demonstrated the formation of Au nanoparticle (NP) arrays on two-dimensional gel patterns based on poly(vinylpyrrolidone) (PVP), which were fabricated by electron beam (EB) lithography. Au NPs were preferentially formed on PVP patterns by photoreduction in HAuCl4-containing MeOH solutions without any surface treatment. The number density of the Au NPs was highly controlled by changing the UV irradiation time; therefore, increasing the UV irradiation time produced Au NP arrays with highly packed Au NPs on the PVP patterns. The size of the cross-linking networks of PVP, which depended on the cross-linking density induced by EB irradiation, plays a very important role in the formation of Au NPs in the Au ion-containing solution under UV irradiation. We discussed the difference in the fabricated Au NP arrays at different EB exposure doses in terms of the interaction between the gel networks and the Au NPs formed.

  5. Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

    Science.gov (United States)

    Boomi, Pandi; Prabu, Halliah Gurumallesh; Manisankar, Paramasivam; Ravikumar, Sundaram

    2014-05-01

    Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

  6. Au rendez-vous allemand (1

    Directory of Open Access Journals (Sweden)

    Agnès Bouvier

    2010-12-01

    Full Text Available Comment traduire, transporter un monde dans un autre, et y faire croire ? La solution de Flaubert pour Salammbô a été d’investir cette difficulté en se plaçant du côté des discours et récits de l’Antiquité, depuis les Anciens et avec eux, retrouvant la parole de l’autre à partir d’une attitude « sympathique » au savoir recueilli. Cette attitude est conforme aux injonctions contemporaines de la « nouvelle école » critique et historique venue d’Allemagne où la pensée de Herder, relayée par Renan, occupe de ce point de vue une place centrale. L’Histoire de la poésie des Hébreux de Herder, paru en 1783, est traduit en français en 1845. Il s’agit d’un ouvrage fondateur de la critique allemande en ce qu’il aborde le texte sacré dans sa dimension exclusivement textuelle. Son titre même est une invitation à envisager la Bible du point de vue de l’art, c’est-à-dire du côté de ses effets : l’exégèse biblique selon Herder doit passer par le déplacement du lieu critique et le développement chez le lecteur moderne d’une sensibilité esthétique identique à celle du lecteur original.How can you translate or transpose one world into another and make it believable?  Flaubert’s solution for Salammbô was to adopt the point of view of Antiquity.  Going back to Antiquity’s speeches and tales, from and with the Classics and our knowledge of them, he chose a sympathetic stance.  This attitude is in line with contemporary admonitions of the “new” critical and historical school that came from Germany where Herder’s thought, passed on by Renan, had a central role.  Herder’s History of Hebrew Poetry, published in 1783, was translated in 1845.  It is a seminal text of German criticism in that it approaches the sacred text in an exclusively textual dimension.  Even the title of his book is an invitation to consider the Bible from the point of view of art, that is, for its effects.

  7. Arnaud Cathrine : des autres au moi

    Directory of Open Access Journals (Sweden)

    Donatella Antonellis

    2012-12-01

    Full Text Available Nos vies romancées est un essai autobiographique où Arnaud Cathrine mélange des souvenirs personnels aux vies et aux livres de six de ses écrivains préférés (Carson McCullers, Françoise Sagan, Roland Barthes, Fritz Zorn, Sarah Kane et Jean Rhys pour s’interroger sur la littérature, sur l’écriture intime et sur la question identitaire. Cet article analyse d'abord l’aspect autobiographique du livre d’Arnaud Cathrine pour en dévoiler les stratégies stylistiques et thématiques aptes à créer une écriture personnelle, comme la présence du je, l’utilisation du temps présent, ainsi que la fonction des adjectifs, des adverbes et du discours direct. Il dévoile ensuite les modalités par lesquelles notre écrivain approche autrui par deux mécanismes en particulier : l’identification et la projection. La rencontre avec l’autre est souvent une défaite mais, malgré tout, l’homme continue sa recherche de quelqu’un auquel appartenir parce qu’« on ne peut pas exister sans double de soi-même ». Existe-t'il alors un lieu où le sujet découvre, par le biais de l’autre, une identité unique et en même temps multiple ? Arnaud Cathrine nous suggère que c’est la littérature qui permet le passage du je au nous : chacun a une vie mais peut la partager et vivre celle d'autrui grâce à la lecture.Nos vies romancées is an autobiographical essay where Arnaud Cathrine blends the personal memories to the life and to the books of his favourite authors (Carson McCullers, Françoise Sagan, Roland Barthes, Fritz Zorn, Sarah Kane and Jean Rhys to talk about literature, private writing and identity. In this text we’ll analyze first the autobiographical side of Arnaud Cathrine’s book to reveal stylistic and thematic strategies used to create a personal writing, such as the presence of I, the use of simple present, the function of adjectives, adverbs and direct speech. Then we’ll show us the modalities to come up to others

  8. Au-Based Catalysts: Electrochemical Characterization for Structural Insights

    Directory of Open Access Journals (Sweden)

    Valentina Pifferi

    2016-02-01

    Full Text Available Au-based catalysts are widely used in important processes because of their peculiar characteristics. The catalyst performance depends strongly on the nature and structure of the metal nanoparticles, especially in the case of bimetallic catalysts where synergistic effects between the two metals can be occasionally seen. In this paper, it is shown that electrochemical characterisation (cyclovoltammetry CV and electrochemical impedance spectroscopy EIS of AuPd systems can be used to determine the presence of an electronic interaction between the two metals, thus providing a strong support in the determination of the nature of the synergy between Au and Pd in the liquid phase oxidation of alcohols. However, it seems likely that the strong difference in the catalytic behavior between the single metals and the bimetallic system is connected not only to the redox behaviour, but also to the energetic balance between the different elementary steps of the reaction.

  9. Hydrogen evolution on Au(111) covered with submonolayers of Pd

    DEFF Research Database (Denmark)

    Björketun, Mårten; Karlberg, Gustav; Rossmeisl, Jan

    2011-01-01

    . The energetics of adsorption and desorption of hydrogen on/from different types of sites on the Pd-Au(111) surface are assessed by means of density functional theory calculations combined with thermodynamic modeling. Based on the density functional and Monte Carlo data, the hydrogen evolution activity......A theoretical investigation of electrochemical hydrogen evolution on Au(111) covered with submonolayers of Pd is presented. The size and shape of monoatomically high Pd islands formed on the Au(111) surface are determined using Monte Carlo simulations, for Pd coverages varying from 0.02 to 0.95 ML...... line defects for Pd island formation and hydrogen evolution are discussed. It is argued, with support from theoretical data, that this kind of defects is likely to be responsible for a dramatic increase in activity observed experimentally [ChemPhysChem 7, 985 (2006); Electrochim. Acta 52, 5548 (2007...

  10. The Adsorption of Nitromethane on the Au (111 Surface

    Directory of Open Access Journals (Sweden)

    F. Illas

    2001-11-01

    Full Text Available The density functional theory (DFT based hybrid-method B3LYP has been used to study the interaction of the nitromethane molecule (CH3NO2 with the Au(111 surface. The perfect Au(111 surface has been represented by a rather large cluster model, Au22, that was in turn used to extract information about the preferred adsorption geometry of the CH3NO2 species. In order to extract energetic information about the stability of adsorbed nitromethane, calculations were also performed for the gas-phase CH3NO2 molecule. The results obtained here are used to interpret experimental data. The computed geometry for adsorbed CH3NO2 agrees with the structure proposed from a previous experimental work.

  11. Triptycene-terminated thiolate and selenolate monolayers on Au(111

    Directory of Open Access Journals (Sweden)

    Jinxuan Liu

    2017-04-01

    Full Text Available To study the implications of highly space-demanding organic moieties on the properties of self-assembled monolayers (SAMs, triptycyl thiolates and selenolates with and without methylene spacers on Au(111 surfaces were comprehensively studied using ultra-high vacuum infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy and thermal desorption spectroscopy. Due to packing effects, the molecules in all monolayers are substantially tilted. In the presence of a methylene spacer the tilt is slightly less pronounced. The selenolate monolayers exhibit smaller defect densities and therefore are more densely packed than their thiolate analogues. The Se–Au binding energy in the investigated SAMs was found to be higher than the S–Au binding energy.

  12. Preparation and evaluation of Au nanoparticle–silica aerogel nanocomposite

    Directory of Open Access Journals (Sweden)

    Naruhito Katagiri

    2015-06-01

    Full Text Available A Au nanoparticle–silica aerogel nanocomposite was prepared by the gelling of a tetramethyl orthosilicate (TMOS/ethanol solution together with Au nanoparticles and drying the wet gel in supercritical carbon dioxide. The aerogel nanocomposite contained Au nanoparticles at a concentration of 0.268 ppm. The bulk density, porosity, and specific surface area of the obtained nanocomposite were 0.126 g/cm3, 94%, and 890 m2/g, respectively. The nanocomposite was reddish-violet in color and transparent, and had a relative permittivity of approximately 6 with a dielectric loss of ca. 1 × 10−3 in the range of 10 MHz to 1 GHz.

  13. Introduction au dossier n°11 Catastrophes et Territoires

    Directory of Open Access Journals (Sweden)

    Philippe Duez

    2008-11-01

    Full Text Available Les risques sont aujourd'hui omniprésents, à tel point que certains voient dans les mutations sociales et organisationnelles actuelles, l'émergence d'une société du risque, avatar, malheureux, d'une société industrielle ayant contribué certes à l'augmentation des richesses, mais au prix d'une absence de maîtrise technique, politique et scientifique des risques inhérents au progrès technique (Beck, 2001.Les sociétés dans leur globalité sont intéressées au premier chef par ces transformations....

  14. Metal(Ni,Au)-vacancy complexes in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Pezold, J. von; Bristowe, P.D. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2006-06-15

    The stability and electronic properties of metal (Ni, Au)-vacancy complexes in GaN were studied using density functional calculations. Two complexes (Ni{sub Ga}-V{sub N} and V{sub Ga}-Au{sub i}-V{sub N}) were found to exhibit relatively low formation energies in their neutral charge state under p-type conditions and are predicted to act as deep acceptors in GaN. As such they are unlikely to contribute to the hole carrier concentration in p-GaN and are probably not responsible for the low electrical resistance of Au/Ni contacts. They may, however, act as compensation centres in n-GaN. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. First principles study on the adsorption of Au dimer on metal-oxide surfaces: The implications for Au growing

    Science.gov (United States)

    Dong, Shan; Zhang, Yanxing; Zhang, Xilin; Mao, Jianjun; Yang, Zongxian

    2017-12-01

    The adsorption of Au dimer on MgO(100), CaO(100), BaO(100), TiO2(110) and YSZ(100) surfaces is comparatively studied using ab initio density functional theory calculations. It is found that Au dimer prefers upright adsorption on MgO(100), CaO(100), BaO(100) surfaces and parallel adsorption on TiO2(110) and YSZ(111) surfaces. According to the analysis of the metal-metal cohesive energy (EAu-Au) and the metal-substrate adhesion energy (EAu-Support), we find that Au adatoms prefer 2D cluster on BaO(100) and TiO2(110) surfaces and 3D cluster on MgO(100), CaO(100) and YSZ(111) surfaces. We also find a linear relationship between EAu-Support/EAu-Au and Eb (binding energy of metal atom on the substrate). Furthermore, an interesting correlation between association energies and the amount of transferred charge is found. The findings may help to gain further insight into the structure-property correlation and provide valuable information on crucial parameters in catalyst design.

  16. Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV.

    Science.gov (United States)

    Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Campbell, S; Chai, J-S; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Chujo, T; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Das, K; David, G; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Fields, D E; Fleuret, F; Fokin, S L; Forestier, B; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S-Y; Gadrat, S; Gastineau, F; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Hachiya, T; Hadj Henni, A; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hiejima, H; Hill, J C; Hobbs, R; Holmes, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hur, M G; Ichihara, T; Iinuma, H; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Kawagishi, T; Kazantsev, A V; Kelly, S; Khanzadeev, A; Kim, D J; Kim, E; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Kochenda, L; Kochetkov, V; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Masui, H; Matathias, F; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakamura, T; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Omiwade, O O; Oskarsson, A; Otterlund, I; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sato, H D; Sato, S; Sawada, S; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Vale, C; Valle, H; van Hecke, H W; Velkovska, J; Vértesi, R; Vinogradov, A A; Vznuzdaev, E; Wagner, M; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Woody, C L; Wysocki, M; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zimányi, J; Zolin, L

    2012-10-12

    We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/cphotons from the inclusive photon sample. The direct photon nuclear modification factor R(AA) was calculated as a function of p(T) for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

  17. The unexpected formation of Au δ+ -Si δ- by the resonance neutralization of Ar + during the low energy bombardment of Au nanoparticles on c-Si

    Science.gov (United States)

    Yang, De-Quan; Sacher, Edward

    2009-05-01

    Nanoscale Au layers, with irregular porosities, have been formed by the low energy Ar + bombardment of Au nanoparticles that were sputter-deposited onto native oxide-covered Si surfaces. High-resolution field emission scanning electron microcopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) have been used to characterize the formation and evolution of the nanoporous layer. Under Ar + bombardment, the Au nanoparticles that were initially deposited were observed to flatten and spread across the native oxide surface, without diffusing, finally coalescing at their edges to form a nanoporous film having irregular pore dimensions. XPS showed that this evolution was accompanied by the loss of Au as a result of sputtering. The formation of such porous films necessitates strong interfacial bonding to avoid the lateral diffusion of the Au nanoparticles, and their ultimate coalescence into larger nanoparticles. We demonstrated that Ar + beam bombardment invariably caused the formation of Au δ+ -Si δ- bonding, rather than the expected Au δ- -Si δ+ bonding, and we explain this to be due to the resonance neutralization of the Ar + beam on impacting the Au layer. We also reveal that the presumed formation of AuSi x is not quantifiable by XPS, due to the superposition of the chemical shift of the Au nanoparticles with that of the quantum size effect, during Au loss on sputtering.

  18. Nuclear ground-state spin of $^{185}$Au and magnetic moments of $^{187, 188}$Au Further evidence for coexisting nuclear shapes in this mass region

    CERN Document Server

    Ekström, C; Ragnarsson, I; Robertsson, L; Wannberg, G

    1980-01-01

    Hyperfine structure measurements have been performed in some neutron- deficient gold isotopes, using online atomic-beam magnetic resonance (ABMR) techniques at the ISOLDE facility, CERN. The following results have been obtained: /sup 185/Au, I=/sup 5///sub 2/; /sup 187/Au, Delta nu =44.35(60) GHz, mu =0.72(7) nm and /sup 188/Au, Delta nu =+or-2992 (30) MHz. The influence of the hyperfine anomaly was discussed. With due regard to this effect, the magnetic moments of /sup 188/Au may be given as mu =+or-0.07(3) nm. The experimental data were compared with the results from calculations based on the particle-asymmetric rotor model. Strong evidence for coexisting nuclear shapes in /sup 185/Au and for a much larger ground-state deformation in /sup 185/Au than in /sup 187/Au was presented. (43 refs).

  19. Expedient Syntheses of Neutral and Cationic Au(I)–NHC Complexes

    KAUST Repository

    Veenboer, Richard M. P.

    2017-09-08

    The synthesis and isolation of gold(I) precatalysts often requires the generation of several isolable intermediates as well as numerous purification steps. New protocols for the expedient synthesis of neutral [Au(OH)(NHC)] and [Au(CH2COCH3)(NHC)] species from [AuCl(NHC)] or [AuCl(DMS)] precursors bearing a variety of N-heterocyclic carbene (NHC) ligands are presented. These methods can be employed in a telescoping manner for the synthesis of catalytically relevant [Au(NTf2)(NHC)] and [Au(NHC)(NCCH3)][BF4] complexes. These attractive methods are straightforward and practical leading to various complexes in high isolated yields and purity.

  20. The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

    Science.gov (United States)

    Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

    2014-09-01

    The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ∼30 to ∼600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ∼200 to ∼500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and

  1. The nucleus 198Au investigated with neutron capture and transfer reactions. I. Experiments and evaluation.

    Science.gov (United States)

    Mayerhofer, Ulrich; von Egidy, Till; Klora, Jörg; Lindner, Helmut; Börner, Hans G.; Judge, Stephen; Krusche, Bernd; Robinson, Stephen; Schreckenbach, Klaus; Sukhovoj, Anatoly M.; Khitrov, Valery A.; Boneva, Stefka T.; Paar, Vladimir; Brant, Slobodan; Pezer, Robert

    The transfer reaction 197Au(d,p)198Au was measured at the Tandem Accelerator in Munich. The 197Au(n,g)198Au and 197Au(n,e)198Au reactions were performed at the High Flux Reactor of ILL, Grenoble. Up to 1560 keV a total of 111 levels were observed by the (d,p) reaction and 125 by the (n,g) reaction. For many of the levels, spins and parities were assigned. Additional information was obtained from summed (n,gg) coincidences measured in Dubna.

  2. Tuning the chemical activity through PtAu nanoalloying: a first principles study

    KAUST Repository

    Mokkath, Junais Habeeb

    2013-06-21

    The electronic structure and adsorption properties of 1.5 nm sized Pt, Au, and PtAu nanoclusters are studied by density functional theory. We explain the recent experimental finding that 20% Au content in PtAu nanoparticles is optimal to induce a dramatically different catalytic behavior. Our results show that the d-band center together with the density of states at the Fermi energy can be used as an indicator of the chemical activity of PtAu nanoclusters. The most favorable adsorption sites on the cluster surfaces as a function of the Pt/Au ratio are identified using atomic H as a probe.

  3. Hexagonal-diamond-like gold lattices, Ba and (Au,T)3 interstitials, and delocalized bonding in a family of intermetallic phases Ba2Au6(Au,T)3 (T = Zn, Cd, Ga, In, or Sn).

    Science.gov (United States)

    Lin, Qisheng; Mishra, Trinath; Corbett, John D

    2013-07-31

    Au-rich polar intermetallics exhibit a wide variety of structural motifs, and this hexagonal-diamond-like gold host is unprecedented. The series Ba2Au6(Au,T)3 (T = Zn, Cd, Ga, In, or Sn), synthesized through fusion of the elements at 700-800 °C followed by annealing at 400-500 °C, occur in space group R3[overline]c (a ≈ 8.6-8.9 Å, c ≈ 21.9-22.6 Å, and Z = 6). Their remarkable structure, generated by just three independent atoms, features a hexagonal-diamond-like gold superstructure in which tunnels along the 3-fold axes are systematically filled by interstitial Ba atoms (blue) and triangles of disordered (Au,T)3 atoms (green) in 2:1 proportions. The Au/Zn mixing in the latter spans ~34 to 87% Zn, whereas the Au/Sn result is virtually invariant compositionally. Complementary bonding between the gold lattice and the disordered (Au,T)3 units is substantial and very regular. Bonding and charge density analyses indicate delocalized bonding within the gold host and the (Au,T)3 triangular units, and moderately polarized bonding between Ba and the electronegative framework. The new structure can also be viewed empirically as the result of an atom-by-triad [i.e., Ba by (Au,T)3 triangle] topological substitution in a BaAu2 (AlB2-type) superstructure.

  4. Dialogue avec les groupes islamistes au Moyen-Orient | CRDI ...

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

    De plus, les gouvernements européens et nord-américains ont tendance à considérer l'Islam politique comme un phénomène uniformément négatif bien que l'idéologie de certains groupes ait considérablement évolué au cours des dernières décennies. Par exemple, les groupes islamistes en Égypte, en Jordanie, au ...

  5. Soutien institutionnel au Groupe de recherche en économie ...

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

    Il a contribué de manière importante au processus d'élaboration des politiques grâce au dynamisme de son directeur qui a porté le tout à bout de bras. ... Le soutien apporté par le CRDI à BetterEvaluation, un réseau international visant à améliorer la théorie et la pratique de l'évaluation, a mené à la création d'un guide en ...

  6. Plasmon-polariton modes of dense Au nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hongdan; Lemmens, Peter; Wulferding, Dirk; Cetin, Mehmet Fatih [IPKM, TU-BS, Braunschweig (Germany); Tornow, Sabine; Zwicknagl, Gertrud [IMP, TU-BS, Braunschweig (Germany); Krieg, Ulrich; Pfnuer, Herbert [IFP, LU Hannover (Germany); Daum, Winfried; Lilienkamp, Gerhard [IEPT, TU Clausthal (Germany); Schilling, Meinhard [EMG, TU-BS, Braunschweig (Germany)

    2011-07-01

    Using optical absorption and other techniques we study plasmon-polariton modes of dense Au nanowire arrays as function of geometrical parameters and coupling to molecular degrees of freedom. For this instance we electrochemically deposit Au nanowires in porous alumina with well controlled morphology and defect concentration. Transverse and longitudinal modes are observed in the absorption spectra resulting from the anisotropic plasmonic structure. The longitudinal mode shows a blue shift of energy with increasing length of the wires due to the more collective nature of this response. We compare our observations with model calculations and corresponding results on 2D Ag nanowire lattices.

  7. Electrochemical characterization of the Au-In-Sb system

    Directory of Open Access Journals (Sweden)

    Gomidželović Lidija D.

    2009-01-01

    Full Text Available The Au-In-Sb system belongs to the group of potential candidates for new lead-free solder materials. Therefore, a lot of investigations concerning its phase diagram and thermodynamic, mechanical, physical characteristics are going on at the moment. Having in mind the significance of such materials application in electronics, it is also very important to study their electrochemical characteristics. In order to give such a characterization, the results of cyclic voltammetry measurements for some alloys in the Au-In-Sb system are presented in this paper.

  8. Nanoshells made easy: improving Au layer growth on nanoparticle surfaces.

    Science.gov (United States)

    Brinson, Bruce E; Lassiter, J Britt; Levin, Carly S; Bardhan, Rizia; Mirin, Nikolay; Halas, Naomi J

    2008-12-16

    The growth of a continuous, uniform Au layer on a dielectric nanoparticle is the critical step in the synthesis of nanoparticles such as nanoshells or nanorice, giving rise to their unique geometry-dependent plasmon resonant properties. Here, we report a novel, streamlined method for Au layer metallization on prepared nanoparticle surfaces using carbon monoxide as the reducing agent. This approach consistently yields plasmonic nanoparticles with highly regular shell layers and is immune to variations in precursor or reagent preparation. Single particle spectroscopy combined with scanning electron microscopy reveal that thinner, more uniform shell layers with correspondingly red-shifted optical resonances are achievable with this approach.

  9. Mechanical behavior of nanoporous Au with fine ligaments

    Science.gov (United States)

    Pia, Giorgio; Delogu, Francesco

    2015-08-01

    A theoretical model relating the overall mechanical behavior of NP metals to the bending response of thick ligaments is developed based on an idealized regular lattice of massive cubic nodes and thick ligaments with square cross section. The model predictions are compared with the Young's modulus and yield strength of nanoporous Au with ligaments a few nanometers in size obtained by numerical simulation and available in literature. It is shown that the model provides a quantitative description of the elastic and plastic deformation of nanoporous Au, reproducing to a considerable extent the numerically estimated Young's modulus and yield strength values.

  10. Organisation and Control of Nanoscale Structures on Au(111)

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Andersen, Jens Enevold Thaulov

    2001-01-01

    We address the formation and characterisation of three different nanoscale systems on single-crystal Au(lll) electrode surfaces in aqueous electrolyte solutions. The systems are investigated particularly by single-crystal electrochernistry and in situ scanning tunnelling rnicroscopy (STM). The [mt...... constitutes a new case for the lise of in situ STM as a tool for manufacturing nanoscale pit structures on IDe Au(lll) surface at small bias voltage. Individually and in combination these data hold perspectives for preparation of atornically planar electrochernical surfaces willi controlled functionalisation...

  11. Cafe au lait has hue of its own.

    Science.gov (United States)

    Orion, Edith; Matz, Hagit; Wolf, Danny; Wolf, Ronni

    2003-12-01

    Segmental pigmentation disorder is a pigmentation disorder (hypo- or hyperpigmentation) first described some 20 years ago. It appears early in life, is segmental, and usually has a sharp border in the midline. It can be confused clinically and histologically with several pigmentary disorders, especially with giant or segmental cafe-au-lait macules. The purpose of this article is to promote, revive, and refresh this somewhat neglected entity, and to further subdivide it into two types: segmental pigmentation disorder simplex and segmental cafe-au-lait. We illustrate our contention with case reports.

  12. Catalytically favorable surface patterns in Pt-Au nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2013-01-01

    Motivated by recent experimental demonstrations of novel PtAu nanoparticles with highly enhanced catalytic properties, we present a systematic theoretical study that explores principal catalytic indicators as a function of the particle size and composition. We find that Pt electronic states in the vicinity of the Fermi level combined with a modified electron distribution in the nanoparticle due to Pt-to-Au charge transfer are the origin of the outstanding catalytic properties. From our model we deduce the catalytically favorable surface patterns that induce ensemble and ligand effects. © The Royal Society of Chemistry 2013.

  13. Metal (Ni, Au)-vacancy complexes in GaN

    Science.gov (United States)

    von Pezold, J.; Bristowe, P. D.

    2006-06-01

    The stability and electronic properties of metal (Ni, Au)-vacancy complexes in GaN were studied using density functional calculations. Two complexes (NiGa-VN and VGa-Aui-VN) were found to exhibit relatively low formation energies in their neutral charge state under p-type conditions and are predicted to act as deep acceptors in GaN. As such they are unlikely to contribute to the hole carrier concentration in p-GaN and are probably not responsible for the low electrical resistance of Au/Ni contacts. They may, however, act as compensation centres in n-GaN.

  14. Site-specific growth of Au-Pd alloy horns on Au nanorods: A platform for highly sensitive monitoring of catalytic reactions by surface enhancement raman spectroscopy

    KAUST Repository

    Huang, Jianfeng

    2013-06-12

    Surface-enhanced Raman scattering (SERS) is a highly sensitive probe for molecular detection. The aim of this study was to develop an efficient platform for investigating the kinetics of catalytic reactions with SERS. To achieve this, we synthesized a novel Au-Pd bimetallic nanostructure (HIF-AuNR@AuPd) through site-specific epitaxial growth of Au-Pd alloy horns as catalytic sites at the ends of Au nanorods. Using high-resolution electron microscopy and tomography, we successfully reconstructed the complex three-dimensional morphology of HIF-AuNR@AuPd and identified that the horns are bound with high-index {11l} (0.25 < l < 0.43) facets. With an electron beam probe, we visualized the distribution of surface plasmon over the HIF-AuNR@AuPd nanorods, finding that strong longitudinal surface plasmon resonance concentrated at the rod ends. This unique crystal morphology led to the coupling of high catalytic activity with a strong SERS effect at the rod ends, making HIF-AuNR@AuPd an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. Using the hydrogenation of 4-nitrothiophenol as a model reaction, we demonstrated that its first-order reaction kinetics could be accurately determined from this platform. Moreover, we clearly identified the superior catalytic activity of the rod ends relative to that of the rod bodies, owing to the different SERS activities at the two positions. In comparison with other reported Au-Pd bimetallic nanostructures, HIF-AuNR@AuPd offered both higher catalytic activity and greater detection sensitivity. © 2013 American Chemical Society.

  15. Competing mechanisms for ordering tendencies in BCC CuAuZn{sub 2} and FCC AuFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.D.; Althoff, J.D. [Sandia National Labs., Livermore, CA (United States); Staunton, J.B.; Ling, M.F. [Warwick Univ., Coventry (United Kingdom). Dept. of Physics; Pinski, F.J. [Cincinnati Univ, OH (United States). Dept. of Physics

    1995-07-01

    We have briefly discussed the ASRO (atomic short-range order) in AuFe and CuAuZn{sub 2}. General points are that (1) we have implemented a first-principles theory of ASRO in N-component alloys which allows determination of the electronic origins of said ASRO; (2) such calculations can provide much information on the high- and (sometimes) low-temperature alloys; and (3) this approach has identified the origin for the novel special-point ASRO in AuFe. Displacement effects, i.e., non-rigid lattice effects, as well as the other contributions beyond band-energy, are being incorporated into the multicomponent alloy calculations. Such improvements will allow us to investigate other alloys, where charge effects may play a role, to ``design`, for example, higher temperature intermetallics through alloying.

  16. Facile preparation of SERS and catalytically active Au nanostructures using furfuryl derivatives

    Science.gov (United States)

    Kim, Ki-Jung; Kim, Hyun-Chul; Park, Minsun; Huh, Seong

    2017-08-01

    Six different types of Au nanostructures with rough surfaces were readily prepared through the redox reactions between Au precursor, AuCl4-, and furfuryl derivatives without extra metal surface capping ligands, in deionized water at room temperature. Furfuryl alcohol (FA) or furfurylamine (FFA) was used as a sole reducing agent for the reduction of Au precursor. Both FA and FFA effectively polymerized during the redox reactions to form polyfuran polymers. These polymers are thought to act as surface capping ligands during the formation of Au nanostructures. Experiments were conducted with three different concentrations of each furfuryl derivative. Interestingly, Au particles prepared from the reaction with varying concentration of FA or FFA showed large differences in size, and revealed that the higher the ratios of [FA]/[AuCl4-] or [FFA]/[AuCl4-], the smaller the size of Au particles. The size of Au particles was in the range of 1 μm to under 30 nm. Among these samples, two nanostructured Au particles, AuFA-4 and AuFFA-1, deposited on a Si wafer by a simple drop-casting method, were revealed as highly active surface-enhanced Raman scattering (SERS) substrates for the detection of methylene blue (MB) and crystal violet (CV). High SERS enhancement factors (EFs) of 106 ∼ 108 for MB and CV were observed. Small size Au nanoparticles (AuFFA-2 and AuFFA-4) were also found to be very active for the catalytic hydrogenation of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 at room temperature. AuFFA-2 could be recycled eight times, without losing its activity.

  17. Antiproton production in Au + Au collisions at 11.7 A{center_dot}GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Sako, Hiroyuki [Tokyo Univ. (Japan)

    1997-02-01

    We investigated the dependence of antiproton yields on the number of wounded projectile nucleons (N{sub proj}). The dN/dy/N{sub proj} of antiprotons with the beam energy correction is almost constant from p+A to Si+A collisions, while it decreases in Au+Au collisions to 30-60% of the constant. Next, we have compared dependence of ratios of dN/dy, p-bar/{pi}{sup -}, p/{pi}{sup -}, K{sup -}/{pi}{sup -}, K{sup +}/{pi}{sup -}, and {pi}{sup +}/{pi}{sup -} at 1.2Au+Au collisions. Only the ratio of p-bar/{pi}{sup -} decreases rapidly, while the ratios of p/{pi}{sup -}, K{sup +}/{pi}{sup -}, and K{sup -}/{pi}{sup -} increase, and {pi}{sup +}/{pi}{sup -} stays constant. These observations suggest that in the AGS energy regime, the absorption effect of antiprotons in Au+Au collisions is much stronger than in p+A and Si+A collisions. We have compared the antiproton data with the RQMD model. In RQMD, antiprotons are produced initially from multi-step excitation processes and some of them are absorbed by nucleons with free NN-bar annihilation cross sections. RQMD reproduces overall tendencies of antiproton yields from p+A to Au+Au collisions within 50%. Finally, we explored the relation between baryon densities and antiproton yields in A+A collisions. We used a model in a static participant volume with the RQMD initial production and the absorption length with the free NN-bar annihilation cross section. In the model, only the antiprotons produced around the surface of the participant volume can survive. The model reproduces the scaling of experimental antiproton yields with the 2/3 power of the number of participants. By comparing the model with the experimental data, it is found that the ratio of the mean baryon density to the surface baryon density is 3-4 independent of collision systems. (J.P.N.). 109 refs.

  18. Freeze-out configuration properties in the 197Au + 197Au reaction at 23 AMeV

    CERN Document Server

    Najman, R; Sochocka, A; Amorini, F; Auditore, L; Cap, T; Cardella, G; De Filippo, E; Geraci, E; Grzeszczuk, A; Kowalski, S; Kozik, T; Lanzalone, G; Lombardo, I; Majka, Z; Nicolis, N G; Pagano, A; Piasecki, E; Pirrone, S; Politi, G; Rizzo, F; Russotto, P; Siwek-Wilczynska, K; Skwira-Chalot, I; Trifiro, A; Trimarchi, M; Wilczynski, J; Zipper, W

    2015-01-01

    Data from the experiment on the 197Au + 197Au reaction at 23 AMeV are analyzed with an aim to find signatures of exotic nuclear configurations such as toroid-shaped objects. The experimental data are compared with predictions of the ETNA code dedicated to look for such configurations and with the QMD model. A novel criterion of selecting events possibly resulting from the formation of exotic freeze-out configurations, "the efficiency factor", is tested. Comparison between experimental data and model predictions may indicate for the formation of flat/toroidal nuclear systems.

  19. Impedance analysis of oxygen reduction in Au nanoparticles; Analisis por impedancia de la reduccion de oxigeno sobre nanoparticulas de Au

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez-Huerta, G.; Ramos-Sanchez, G. [Cinvestav-IPN, Mexico, D.F. (Mexico)]. E-mail: gervazkez@gmail.com; Antano-Lopez, R. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S. C., Pedro Escobedo, Queretaro (Mexico); Solorza-Feria, O. [Cinvestav-IPN, Mexico, D.F. (Mexico)

    2009-09-15

    Nanometric-sized ({approx}5nm) Au particles were synthesized using the chemical reduction of AuCl{sub 3} with NaBH{sub 4}. The Au particles were analyzed with x-ray diffraction (XRD), finding that the particles are highly crystalline, with a face-centered cubic (FCC) structure. The impedance spectrums obtained in 0.5M H{sub 2}SO{sub 4} solution saturated with O{sub 2}, at potentials greater than 0.38 V vs NHE, show one single temperature constant associated with the reduction in O{sub 2} on Au particles, producing hydrogen peroxide (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). At potentials less than 0.38 V, a second constant temperature appears associated with a second process, that is, the reduction of H{sub 2}O{sub 2} to H{sub 2}O. [Spanish] Particulas de Au con tamano nanometrico ({approx}5nm) fueron sintetizadas a partir de la reduccion quimica del AuCl{sub 3} con NaBH{sub 4}. Las particulas de Au fueron analizadas con difraccion de rayos X (XRD), se encontro que las particulas son altamente cristalinas, con una estructura cubica centrada en las caras (FCC). Los espectros de impedancia obtenidos en solucion 0.5M H{sub 2}SO{sub 4} saturada con O{sub 2}, a potenciales mayores de 0.38 V vs NHE muestran una sola constante de tiempo, asociada a la reduccion de O{sub 2} sobre las particulas de Au, dando como producto peroxido de hidrogeno (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). A potenciales menores de 0.38 V aparece una segunda constante de tiempo, asociada a un segundo proceso, i.e. la reduccion del H{sub 2}O{sub 2} a H{sub 2}O.

  20. Pion Interferometry of square root of (s(NN)) =130 GeV Au + Au collisions at RHIC.

    Science.gov (United States)

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Bossingham, R; Boucham, A; Brandin, A; Cadman, R V; Caines, H; Calderón De La Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Conin, L; Cormier, T M; Cramer, J G; Crawford, H J; DeMello, M; Deng, W S; Derevschikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grabski, J; Grachov, O; Greiner, D; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Y I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; McShane, T S; Meissner, F; Melnick, Y; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Pinganaud, W; Platner, E; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schweda, K; Schmitz, N; Schroeder, L S; Schüttauf, A; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Stroebele, H; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Sumbera, M; Symons, T J; Szanto De Toledo, A; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Tikhomirov, V; Trainor, T A; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2001-08-20

    Two-pion correlation functions in Au+Au collisions at square root of [s(NN)] = 130 GeV have been measured by the STAR (solenoidal tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The Hanbury Brown-Twiss parameters display a weak energy dependence over a broad range in square root of [s(NN)].

  1. Elliptic flow due to charged hadrons for Au+Au collisions at RHIC energy 62.4 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Somani Ajit, E-mail: ajit.somani@gmail.com [Department of Physics, Suresh Gyan Vihar University, Jaipur, Rajasthan, INDIA (Presently working at Govt. Polytechnic College, Hanumangarh, Rajasthan, INDIA) (India); Sudhir, Bhardwaj [Govt. College of Engineering & Technology, Bikaner, Rajasthan (India); Ashish, Agnihotri [Department of Physics, SBCET, Jaipur, Rajasthan (India)

    2016-05-06

    Elliptic flow is an important observable in search of Quark Gluon Plasma. The elliptic flow parameter dependence on centrality due to charged hadrons were studied using events generated by event generator AMPT at center of mass energy of 62.4 GeV per nucleon pair for Au+Au collisions. This study performed for pseudorapidity range from −0.35 to 0.35 and transverse momentum bins p{sub t} = 0.2 to 1 GeV/c and 1 to 2 GeV/c. We compared the results obtained from simulated data and RHIC-PHENIX data.

  2. manifestations ophtalmologiques au cours du syndrome d'apert

    African Journals Online (AJOL)

    Il faut insister sur la nécessité d'un bilan ophtalmologique soigneux avant et après la chirurgie. J. TUN ORL - N° 18 JUIN 2007. 47. MANIFESTATIONS OPHTALMOLOGIQUES AU COURS DU SYNDROME D'APERT. Fig. 3 : Champ visuel automatique: scotomes absolus. Fig. 1 : Syndrome d'Apert :exophtalmie. Fig. 2 : Photo ...

  3. EST Table: AU000257 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU000257 e40305 10/09/28 100 %/168 aa ref|NP_001040343.1| peripheral-type benzodiazepine... receptor [Bombyx mori] gb|ABF51223.1| peripheral-type benzodiazepine receptor [Bombyx mori] 10/08/27 5

  4. EST Table: AU005167 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU005167 ws30338 11/12/09 GO hit GO:0016021(integral to membrane)|GO:0019645(anaerobic... electron transport chain) 10/09/28 70 %/200 aa emb|CBG33812.1| anaerobic dimethyl sulfoxide reductase ch

  5. EST Table: AU005278 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU005278 ws30487 10/09/28 88 %/235 aa ref|NP_001036933.1| molting fluid carboxypept...idase A [Bombyx mori] dbj|BAD60916.1| molting fluid carboxypeptidase A [Bombyx mori] 10/08/28 40 %/243 aa FB

  6. EST Table: AU004198 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU004198 ws20048 10/09/28 85 %/202 aa ref|NP_001036933.1| molting fluid carboxypept...idase A [Bombyx mori] dbj|BAD60916.1| molting fluid carboxypeptidase A [Bombyx mori] 10/08/28 39 %/115 aa FB

  7. Inverse photoemission studies of C-60 on Au(110)

    NARCIS (Netherlands)

    Pedio, M.; Grilli, M.L.; Ottaviani, C.; Capozi, M.; Quaresima, C.; Perfetti, P.; Thiry, P.A.; Caudano, R.; Rudolf, P.

    1995-01-01

    The unoccupied states of C60 have been studied for single monolayer and multilayer coverages on Au(110) with Inverse Photoemission Spectroscopy (IPES). In agreement with previous results on C60 on gold, we find that only the first monolayer, which is chemisorbed, shows a different spectrum compared

  8. Electronic Structure of Au25 Clusters: Between Discrete and Continuous

    KAUST Repository

    Katsiev, Khabiboulakh

    2016-07-15

    Here, an approach based on synchrotron resonant photoemission is emplyed to explore the transition between quantization and hybridization of the electronic structure in atomically precise ligand-stabilized nanoparticles. While the presence of ligands maintains quantization in Au25 clusters, their removal renders increased hybridization of the electronic states at the vicinity of the Fermi level. These observations are supported by DFT studies.

  9. Au nanoparticles improve amorphous carbon to be gas sensors

    Science.gov (United States)

    Liu, Keng-Wen; Lee, Jian-Heng; Chou, Hsiung; Lin, Tzu-Ching; Lin, Si-Ting; Shih-Jye Sun Collaboration

    In order to make the amorphous carbon possess the gas sensing capability transferring some sp3 orbits to sp2 is necessary. It is proposed that the metallic materials having a large charge exchange with sp3 carbon orbits are being catalysts to transfer the carbon orbits. We found embedding gold nanoparticles to the amorphous carbon will induce many compact sp2 orbits around the nanoparticles, which make the amorphous carbon be the candidate material for the gas sensors. The orbits of amorphous carbon near the interface of Au nanoparticles can be changed from sp3 to compact sp2 to reduce the surface energy of Au nanoparticles. Meanwhile, our molecular dynamics simulation has confirmed the fact, when an Au nanoparticle is embedded in the amorphous carbon system the ratio of sp2 orbits increases dramatically. Similar results also have been confirmed from the Raman spectrum measurements. We controlled the carrier transport by changing the hopping barriers formed by amorphous carbon matrix between the Au nanoparticles to modify the resistance. These nanocomposites exhibit a superior sensitivity to NH3 at room temperature as well as good reproducibility and short response/recovery times, which could have potential applications in gas sensors. Dept. of Applied Physics,NUK, Kaohsiung, Taiwan.

  10. EST Table: AU005545 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available 00163009 [Acyrthosiphon pisum] dbj|BAH72916.1| ACYPI004125 [Acyrthosiphon pisum] dbj|BAH72917.1| ACYPI004125 [Acyrthosiphon pisum...AU005545 ws30838 10/09/28 45 %/117 aa ref|NP_001156155.1| hypothetical protein LOC1

  11. EST Table: AU000418 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU000418 e40523 11/12/09 GO hit GO:0016747(transferase activity, transferring acyl groups... other than amino-acyl groups) 10/09/28 100 %/162 aa emb|CBG34003.1| putative acyltransferase [Escheri

  12. Pratique de l'échocardiographie transoesophagienne au Burkina ...

    African Journals Online (AJOL)

    Pratique de l'échocardiographie transoesophagienne au Burkina Faso: analyse situationnelle et perspectives de développement. N.V. Yaméogo, L.J. Kagambèga, G.R.C. Millogo, A Niankara, K.J. Kologo, B.J.Y. Toguyéni, A Samadoulougou, P Zabsonré ...

  13. La participation citoyenne en contexte local au Cameroun. Entre ...

    African Journals Online (AJOL)

    d'une urgence participative, il analyse les principaux modèles de participation en œuvre au. Cameroun en mobilisant le ... Mots-clés : Action publique, Cameroun, échelle locale, mini-public, participation citoyenne. Abstract: This paper ...... réticents à cette approche de cooptation, les CAD deviennent formellement et parfois.

  14. COMPORTEMENT DE CLONES DE PALMIER A HUILE AU CHAMP ...

    African Journals Online (AJOL)

    AISA

    Agronomie Africaine 15 (1) : 29-38 (2003). 29. COMPORTEMENT DE CLONES DE PALMIER A HUILE AU. CHAMP EN ZONES DE HAUTE DENSITE DE Fusarium oxysporum f. sp. elaeidis EN COTE D'IVOIRE. K. ALLOU1 , N. AHOUSSOU2, S. AKE2, S. DIABATE3. ET DE H. FRANQUEVILLE4. 1CNRA station de recherche ...

  15. EST Table: AU000330 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available 8 100 %/240 aa ref|NP_001170882.1| tan protein [Bombyx mori] dbj|BAI87831.1| Tan [Bombyx mori] 10/08/27 50 %...|ref|XP_971848.1| PREDICTED: similar to tan CG12120-PA [Tribolium castaneum] AU000330 e4 ...

  16. Facile Growth of Multi-twined Au Nanostructures

    Indian Academy of Sciences (India)

    controlling the shape and morphology of the metal particles. Umar and Oyama have reported the high yield synthesis of branched Au nanostructures using binary mixture of CTAB and hexamethylenetetramine by the seed-mediated growth approach.32 Liz-Marzan reported the synthesis of thorned nanowires by the.

  17. Compositional changes of Pd-Au bimetallic nanoclusters upon hydrogenation

    NARCIS (Netherlands)

    Di Vece, M.|info:eu-repo/dai/nl/248753355; Bals, S.; Verbeeck, J.; Lievens, P.; Van Tendeloo, G.

    2009-01-01

    Changes in the size distribution and composition of bimetallic Pd-Au nanoclusters have been observed after hydrogen exposure. This effect is caused by hydrogen-induced Ostwald ripening whereby the hydrogen reduces the binding energy of the cluster atoms leading to their detachment from the cluster.

  18. Lightcurve Analysis for Minor Planet 138925 2001 AU43

    Science.gov (United States)

    Mollica, Maurizio; Noschese, Alfonso; Vecchione, Antonio; D'Avino, Luca

    2018-01-01

    From 2017 July 27-30, CCD images were collected with the aim to determine the rotation period of (138925) 2001AU43. The data analysis gives a complex lightcurve with a rotation period of 5.251 ± 0.001 h.

  19. Formation of Au and tetrapyridyl porphyrin complexes in superfluid helium.

    Science.gov (United States)

    Feng, Cheng; Latimer, Elspeth; Spence, Daniel; Al Hindawi, Aula M A A; Bullen, Shem; Boatwright, Adrian; Ellis, Andrew M; Yang, Shengfu

    2015-07-14

    Binary clusters containing a large organic molecule and metal atoms have been formed by the co-addition of 5,10,15,20-tetra(4-pyridyl)porphyrin (H2TPyP) molecules and gold atoms to superfluid helium nanodroplets, and the resulting complexes were then investigated by electron impact mass spectrometry. In addition to the parent ion H2TPyP yields fragments mainly from pyrrole, pyridine and methylpyridine ions because of the stability of their ring structures. When Au is co-added to the droplets the mass spectra are dominated by H2TPyP fragment ions with one or more Au atoms attached. We also show that by switching the order in which Au and H2TPyP are added to the helium droplets, different types of H2TPyP-Au complexes are clearly evident from the mass spectra. This study suggests a new route for the control over the growth of metal-organic compounds inside superfluid helium nanodroplets.

  20. Using Dawn to Observe SEP Events Past 2 AU

    Science.gov (United States)

    Villarreal, Michaela; Russell, Christopher T.; Prettyman, Thomas H.

    2017-10-01

    The launch of the STEREO spacecraft provided much insight into the longitudinal and radial distribution of solar energetic particles (SEPs) relative to their origin site. However, almost all of the observations of SEP events have been made exclusively near 1 AU. The Dawn mission, which orbited around Vesta before arriving at Ceres, provides an opportunity to analyze these events at much further distances. Although Dawn's Gamma Ray and Neutron Detector (GRaND) is not optimized for SEP characterization, it is sensitive to protons greater than 4 MeV, making it capable of detecting a solar energetic particle event in its vicinity. Solar energetic particles in this area of the solar system are important as they are believed to cause sputtering at bodies such as Ceres and comets (Villarreal et al., 2017; Wurz et al., 2015). In this study, we use Dawn’s GRaND data from 2011-2015 when Dawn was at distances between 2-3 AU. We compare the SEP events seen by Dawn with particle measurements at 1 AU using STEREO, Wind, and ACE to understand how the SEP events evolved past 1 AU.References: Villarreal, M. N., et al. (2017), The dependence of the Cerean exosphere on solar energetic particle events, Astrophys. J. Lett., 838, L8.Wurz, P. et al. (2015), Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko, A&A, 583, A22.

  1. Statistical Evaluation of Geochemical Au Sample Quality | Affam ...

    African Journals Online (AJOL)

    To prevent the frequency of these occurrences, quality control checks coupled with classical statistical probe can form an integral part of the checklist to eliminate these errors. Although duplicate results have often accompanied original Au assays in most analytical reports submitted by laboratories, it is not immediately ...

  2. Pratiques manageriales et stress au travail chez les salaries ...

    African Journals Online (AJOL)

    Par ailleurs, le management centré sur les résultats de l'entreprise contribue plus au développement du stress que celui axé sur le social (le personnel). Mots-clés: stress, relations hiérarchiques, communication, management, salarié. English Title: Managerial practices and work stress on Abidjan employees.

  3. EST Table: AU006246 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU006246 wv40750 10/09/28 52 %/103 aa ref|XP_973163.1| PREDICTED: similar to jumpin...gnl|Amel|GB14856-PA 10/09/10 52 %/103 aa gi|91086783|ref|XP_973163.1| PREDICTED: similar to jumping translocation breakpoint protein [Tribolium castaneum] FS906679 wv4 ...

  4. Density functional theory investigation of benzenethiol adsorption on Au(111)

    DEFF Research Database (Denmark)

    Nara, Jun; Higai, Shin’ichi; Morikawa, Yoshitada

    2004-01-01

    We have studied the adsorption of benzenethiol molecules on the Au(111) surface by using first principles total energy calculations. A single thiolate molecule is adsorbed at the bridge site slightly shifted toward the fcc-hollow site, and is tilted by 61degrees from the surface normal. As for th...

  5. PHENIX results on flow observables in asymmetric Cu + Au collisions

    Science.gov (United States)

    Schaefer, B.

    2016-12-01

    Measurements of anisotropic flow from Cu+Au √{sNN} = 200 GeV collisions in PHENIX at RHIC in 2012 are presented for inclusive charged particles and identified hadrons π±, K±, p, and p ‾ at midrapidity. Fourier coefficients characterizing the azimuthal distribution of produced particles with respect to the event plane measured at forward rapidity are examined over a broad range of pT and collision centrality. Directed, elliptic, and triangular moments (v1, v2, v3 as functions of pT) all exhibit mass ordering. Comparisons are made to Cu+Cu and Au+Au systems as well as to hydrodynamical and transport model calculations [A. Adare, et al., "Measurements of directed, elliptic, and triangular flow in Cu+Au collisions at √{sNN} = 200 GeV", arXiv:1509.07784.]. Unlike v2 and v3, v1 decreases with centrality, mass ordering is seen for all three, and v2 and v3 with respect to transverse momentum feature common scaling with 1 / (εnNpart1/3).

  6. Tuberculose hépatique nodulaire: complication inhabituelle au ...

    African Journals Online (AJOL)

    -tumorale dont le tableau clinico-biologique et radiologique initial était aspécifique. Il s'agit d'un jeune marocain suivi pour maladie de Wilson et présentant une fièvre au long cours. L'imagerie met en évidence une lésion nodulaire hépatique ...

  7. New ideally absorbing Au plasmonic nanostructures for biomedical applications

    Science.gov (United States)

    Zakomirnyi, Vadim I.; Rasskazov, Ilia L.; Karpov, Sergey V.; Polyutov, Sergey P.

    2017-01-01

    In this paper a new set of plasmonic nanostructures operating at the conditions of an ideal absorption (Grigoriev et al., 2015 [1]) was proposed for novel biomedical applications. We consider spherical x/Au nanoshells and Au/x/Au nanomatryoshkas, where 'x' changes from conventional Si and SiO2 to alternative plasmonic materials (Naik and Shalaev, 2013 [2]), such as zinc oxide doped with aluminum, gallium and indium tin oxide. The absorption peak of proposed nanostructures lies within 700-1100 nm wavelength region and corresponds to the maximal optical transparency of hemoglobin and melanin as well as to the radiation frequency of available pulsed medical lasers. It was shown that the ideal absorption takes place in a given wavelength region for Au coatings with thickness less than 12 nm. In this case finite quantum size effects for metallic nanoshells play a significant role. The mathematical model for the search of the ideal absorption conditions was modified by taking into account the finite quantum size effects.

  8. January 2010 Port-au-Prince, Haiti Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — According to official estimates, 222,570 people killed, 300,000 injured, 1.3 million displaced, 97,294 houses destroyed and 188,383 damaged in the Port-au-Prince...

  9. EST Table: AU002521 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available AU002521 n0069 11/12/09 n.h 10/09/28 41 %/103 aa ref|XP_002431503.1| enzymatic poly...protein; Endonuclease; Reverse transcriptase, putative [Pediculus humanus corporis] gb|EEB18765.1| enzymatic

  10. Au-Biocompatible metallic nanostructures in metalloprotein electrochemistry and electrocatalysis

    DEFF Research Database (Denmark)

    Jensen, Palle Skovhus; Engelbrekt, Christian; Sørensen, Karsten Holm

    2012-01-01

    Molecular scale metallic nanoparticles coated by molecular monolayers and immobilized on single-crystal Au-electrode surfaces are efficient catalysts in metalloprotein voltammetry. Nanoparticles prepared by a new ‘‘green’’ method also exhibit strong electrocatalysis in both protein electrochemist...

  11. Nitrogen mineralization from 'AU Golden' sunn hemp residue

    Science.gov (United States)

    The tropical legume sunn hemp (Crotalaria juncea) cultivar ‘AU Golden’ has the potential to provide substantial amounts of nitrogen (N) to subsequent crops that could reduce recommended application rates of synthetic N fertilizers. Nitrogen fertilization problems via legumes are often due to asynch...

  12. L'APPRENTISSAGE AU CERN - French version only

    CERN Document Server

    Roland Gay

    2002-01-01

    APPRENTISSAGES TECHNIQUES FORMATION ET DEVELOPPEMENT HR/TD/AP L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 7 places au total sont ouvertes au recrutement pour les deux professions. L'apprentissage dure 4 ans. Minima requis pour faire acte de candidature :   avoir terminé la scolarité obligatoire être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne, Finlande, France, Grèce, Hongrie, Italie, Norvège, Pays-Bas, Pologne, Portugal, République slovaque, République tchèque, Royaume-Uni, Suède, Suisse) avoir au moins 15 ans et moins de 21 ans à la date de début de ...

  13. L'APPRENTISSAGE AU CERN - French version only

    CERN Document Server

    Roland GAY

    2002-01-01

    APPRENTISSAGES TECHNIQUES FORMATION ET DEVELOPPEMENT HR/TD/AP L'APPRENTISSAGE AU CERN pour les professions d'électronicien(ne) et de laborant(ine) en physique L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 7 places au total sont ouvertes au recrutement pour les deux professions. L'apprentissage dure 4 ans. Minima requis pour faire acte de candidature :   avoir terminé la scolarité obligatoire être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne, Finlande, France, Grèce, Hongrie, Italie, Norvège, Pays-Bas, Pologne, Portugal, République slovaque, République tchèque, Royaume-Uni, Su&a...

  14. au gmented local anaesthesia in selected cases of thyroidectomy in ...

    African Journals Online (AJOL)

    June 200i, Vol. 7(1); 31 — 32. AU GMENTED LOCAL ANAESTHESIA IN SELECTED CASES OF. THYROIDECTOMY IN RURAL PRACTICE. E. F. A1uf0hai* O. O. Odusanya** ... immediately relieved after the administration of general anaesthesia. The result ... 1% lidocaine hydrochloride with adrenaline acid tartrate .BP in.

  15. IRAS investigation of a catenane adsorption on Au(111)

    NARCIS (Netherlands)

    Fustin, CA; Haq, S; Wingen, A; Gregoire, C; Raval, R; Dumas, P; Hannam, JS; Leigh, DA; Rudolf, P

    2005-01-01

    The adsorption of a benzylic amide [2]catenane on a Au(1 1 1) single crystal has been studied using infrared reflection absorption spectroscopy. The evolution of the infrared spectra during catenane deposition at different temperatures of the gold substrate (300 and 90 K) has been compared. Evidence

  16. Trypanosomoses animales dans la Plaine de Mô au Togo | Talaki ...

    African Journals Online (AJOL)

    Les trypanosomoses animales africaines (TAA) demeurent une des contraintes majeures au développement de l'élevage en Afrique subsaharienne. La présente étude a été conduite en mars 2013 dans cinq (5) localités correspondant aux cantons (Boulohou, Djarkpanga, Kangnigbara, Saiboudè et Tindjassi) de la Plaine ...

  17. Au Cern, premières collisions de protons hier

    CERN Multimedia

    Galeazzi, Juliette

    2009-01-01

    "Hier, les scientifiques du monde entier ont salué le redémarrage du LHC, grand collisionneur de hadrons, au Cern à Genève. Après quatorze mois d'arrêt, à la suite d'une panne, les expériences ont pris et les premières collisions ont eu lieu" (2 pages)

  18. Templated Control of Au nanospheres in Silica Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, J W; Vanamu, G; Zaidi, S H

    2007-03-15

    The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with minimum area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

  19. Sécurité alimentaire et changements climatiques au Cambodge ...

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

    Sécurité alimentaire et changements climatiques au Cambodge. Le Cambodge est l'un des pays les plus pauvres d'Asie. Quelque 70 % de la population gagne sa vie grâce à l'agriculture. L'insécurité alimentaire, dont souffre un nombre grandissant de personnes, touche particulièrement les populations rurales.

  20. Facile one-pot synthesis of luminescent-thiolated Au nanocluster and Au(I)-thiolate complexes as highly selective Cu2+ probes

    Science.gov (United States)

    Pal, Nabin Kumar; Kryschi, Carola

    2015-05-01

    Here in this paper, we reported of a facile photo-induced one-step method for synthesizing highly luminescent Au(I)-thiolate complexes (size 2-3 nm) and thiolated Au nanocluster (AuNC, size 1.6 nm). The hydrophilic thiol being 3-mercaptopropanoic acid (3-MPA) was used as stabilizing agent. The as-prepared Au(I)-thiolate complexes exhibit bright red photoluminescence (PL) and were used as an efficient sensor for the selective detection of Cu2+ ions. We also observed the formation of thiol-stabilized Au nanoparticles through continuous electron beam irradiation of Au(I)-thiolated complexes. The Au(I)-thiolate complexes show a PL lifetime on the μs time scale, whereas the PL lifetime of the thiolated AuNC is on the ns time scales. The photo-physical, electronic, structural and morphological properties of the thiolated AuNC and Au(I)-thiolate complexes were examined upon performing UV-Vis absorption spectroscopy, stationary and time-resolved PL spectroscopy, X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy and transmission electron microscopy experiments.

  1. Facile one-pot synthesis of luminescent-thiolated Au nanocluster and Au(I)–thiolate complexes as highly selective Cu{sup 2+} probes

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Nabin Kumar; Kryschi, Carola, E-mail: carola.kryschi@fau.de [Friedrich-Alexander University of Erlangen-Nuremberg, Department of Chemistry and Pharmacy and ICMM (Germany)

    2015-05-15

    Here in this paper, we reported of a facile photo-induced one-step method for synthesizing highly luminescent Au(I)–thiolate complexes (size ∼2–3 nm) and thiolated Au nanocluster (AuNC, size ∼1.6 nm). The hydrophilic thiol being 3-mercaptopropanoic acid (3-MPA) was used as stabilizing agent. The as-prepared Au(I)–thiolate complexes exhibit bright red photoluminescence (PL) and were used as an efficient sensor for the selective detection of Cu{sup 2+} ions. We also observed the formation of thiol-stabilized Au nanoparticles through continuous electron beam irradiation of Au(I)–thiolated complexes. The Au(I)–thiolate complexes show a PL lifetime on the μs time scale, whereas the PL lifetime of the thiolated AuNC is on the ns time scales. The photo-physical, electronic, structural and morphological properties of the thiolated AuNC and Au(I)–thiolate complexes were examined upon performing UV–Vis absorption spectroscopy, stationary and time-resolved PL spectroscopy, X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy and transmission electron microscopy experiments.

  2. Spin reorientation transition in Co/Au multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Quispe-Marcatoma, J., E-mail: jquispem@unmsm.edu.pe [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Tarazona, H. [Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Pandey, B. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Pune 412 115, India. (India); Sousa, M.A. de [Instituto de Física, Universidade Federal de Goiás, Goiânia 74001-970 (Brazil); Carvalho, M. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Landauro, C.V. [Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, P.O. Box 14-0149, Lima 14, Perú (Peru); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia 74001-970 (Brazil); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil)

    2014-10-01

    We report a study about the spin reorientation transition (SRT) from perpendicular easy axis to in-plane easy axis of magnetization in Co/Au multilayers. A series of multilayers of Si/Au(100 Å)/{[Co(t_C_o)/Au(20 Å)]_2_0}/Au(50 Å) family were studied, with Co layer thickness varying between 6 Å to 30 Å. The thickness of the Au layer was chosen large enough in order to minimize the interlayer exchange coupling between Co layers. In such thick Au-layer samples the magnetic properties are mainly the result of competition between interlayer magnetostatic coupling due to stray field, perpendicular magnetic anisotropy and shape anisotropy. The effective anisotropy constant K{sub eff} and the second order anisotropy K{sub 2} were deduced from the fit of the resonant magnetic field obtained from out of plane dependence Ferromagnetic Resonance (FMR) experiments. To study the SRT, we have plotted the phase diagram between K{sub eff} and K{sub 2}. The results show that SRT occurs through the metastable region with K{sub 2} ≤ −½ K{sub eff}, (K{sub eff} > 0). It is interesting to note that FMR shows the coexistence of two modes with different anisotropy for small Co thickness, while for thick Co layers the modes have the same anisotropy. Moreover, in thick Co layer samples, volume and surface spin wave resonance (SWR) modes were also excited by the microwave field, around the perpendicular FMR geometry, giving a clear evidence of a magnetic coupling between the Co layers. - Highlights: • Co/Au multilayers with varying Co layer thickness are prepared by DC-magnetron sputtering. • The spin reorientation transition (SRT) and flipping of magnetic moment are studied. • Effective anisotropy constant (K) and 2nd order anisotropy constant (K{sub 2}) are calculated. • K Vs K{sub 2} plot showed that SRT occurs through the metastable region with K{sub 2} ≤ −½ K, (K > 0). • Ferromagnetic Resonance spectra showed the coexistence of two resonance modes.

  3. Carlin-type Au Deposits in Nevada: Unique Hydrothermal Systems?

    Science.gov (United States)

    Cline, J. S.

    2006-05-01

    Carlin-type gold deposits (CTGD) in Nevada have huge Au endowments that have made Nevada one of the leading Au producers in the world. Although they form one of the three most productive Au districts in the world, the deposits were not discovered until the early 1960's owing primarily to the lack of visible Au. Numerous studies have provided a detailed geologic picture of the deposits, yet a comprehensive and widely accepted genetic model remains elusive because of 1) difficulties in identifying and analyzing the fine-grained, volumetrically minor, and common ore and gangue minerals, 2) approximately contemporaneous mineralization that overprinted or was overprinted by Carlin-type mineralization, and 3) post-ore weathering and oxidation. Geologic data from all districts indicate compelling similarities, suggesting that all deposits formed in response to similar geologic processes. Yet, stable isotope studies suggest multiple sources for ore fluids and components. Because of these inconsistencies, current models relate deposits to 1) metal leaching and transport by convecting meteoric water, 2) hydrothermal fluids exsolved from epizonal intrusions, and 3) deep metamorphic and/or magmatic fluids. Proterozoic to early Paleozoic rifting produced a passive margin sequence of reactive calcareous host rocks, and NNW- and WNW-striking basement and Paleozoic normal faults that may control the trends. Following rifting, the host rocks were subjected to compressional orogenies, developing a pre-mineral architecture of steeply dipping fluid conduits and shallow dipping traps. NNW- and WNW-striking basement and Paleozoic normal faults were inverted during these compressional events and formed structural culminations including anticlines and domes that served as depositional sites for ore fluids. Au-bearing pyrite precipitated 42-36 m.y. ago as northwesterly to westerly extension reopened favorably oriented older structures. Fluid flow and mineral deposition appear to have been

  4. The Au-Hosting Minerals and Process of Formation of the Carlin-Type Bojitian Deposit, Southwestern China

    Directory of Open Access Journals (Sweden)

    Kai Hu

    2017-01-01

    Full Text Available The recently discovered middle-sized Bojitian Carlin-type Au deposit is located in southwestern Guizhou Province, China, near the well-known Shuiyindong super-large-sized deposit. To improve the understanding on this deposit, here we investigate the minerals that host Au and the occurrence of Au in the deposit, using a combination of microscopic work and electron probe microanalysis (EPMA. Based on the results, the formation of the deposit was addressed. Results indicate that the dominant minerals that host Au include arsenian pyrite and arsenopyrite. Au in the cores of zoned pyrite exists mainly as natural nanoscale Au (Au0, while Au in the rims exists mainly as solid solution Au (Au+, but it likely also exists in the rims as natural nanoscale Au. The framboidal, coarse-grained, and banded pyrite types contain both natural nanoscale Au0 and solid solution Au+. The arsenopyrite is of hydrothermal origin, and Au within the arsenopyrite exists as gold solution Au+. The Bojitian deposit was formed from As-bearing, H2S-rich, low-to-medium-temperature fluids that migrated along faults and other channels. Au that was already present in the strata or source beds migrated with the fluids in the form of Au(HS− and ore-forming fluids were then formed in the reducing environment. The ore-forming fluids interacted with Fe-rich carbonates to form an abundance of Au-hosting arsenian sulfides.

  5. Au Pair and Trafficked? - Recruitment, Residence in Denmark and Dreams for the Future

    DEFF Research Database (Denmark)

    Korsby, Trine Mygind

    Report on the prevalence and risk of human trafficking in the situations and experiences of a group of au pairs in Denmark. The report is based on a qualitative study with interviews with 27 au pairs living in Denmark. The au pairs come from the Philippines, Belarus, Ukraine, Serbia, Nepal and Ke...

  6. Low-pressure ETEM Studies of Au assisted MgO Nanorod Growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum

    2014-01-01

    Environmental transmission electron microscopy (ETEM) studies MgO nanorod growth from Au catalyst nanoparticles in a controlled gas atmosphere have been performed, in order to elucidate the mobility of Au surface atoms and the configuration of the Au/MgO interface. MgO nanorod growth is driven...

  7. Pt–Au/C cathode with enhanced oxygen-reduction activity in PEFCs

    Indian Academy of Sciences (India)

    ... 1:1 Pt–Au/C catalysts, (3:1) Pt–Au/C exhibits maximum electrochemical activity towards ORR. Powder X-ray diffraction pattern and transmission electron micrograph suggest Pt–Au alloy nanoparticles to be well dispersed onto the carbon-support. Energy dispersive X-ray analysis and inductively coupled plasma-optical ...

  8. Ethanol Sensing Properties of Au-functionalized NiO Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sunghoon; Kheel, Hyejoon; Sun, Gun-Joo; Hyun, Soong Keun; Park, Sang Eon; Lee, Chongmu [Inha University, Incheon (Korea, Republic of)

    2016-05-15

    Pristine and Au-functionalized nickel oxide (NiO) nanoparticles were synthesized via a simple solvo thermal route and the ethanol sensing properties of multiple-networked Au-doped and undoped NiO nanoparticle sensors were examined. The pristine and Au-functionalized NiO nanoparticle sensor showed responses of 442 and 273%, respectively, to 1000 ppm of ethanol at 325 .deg. C. The Au-functionalized NiO nanoparticle sensor showed faster response than the pristine NiO counterpart, whereas the recovery time of the former was similar to that of the latter. The optimal operating temperature of the pristine and Au-functionalized NiO nanoparticles was 325 and 350 .deg. C, respectively, by Au-doping. Both the pristine and Au-functionalized NiO nanoparticle sensors showed selectivity for ethanol gas over methanol, acetone, benzene, and toluene gases. The underlying mechanism of the enhanced sensing performance of the Au-functionalized NiO nanoparticles toward ethanol might be due to modulation of the depletion layer formed around Au particles and the Schottky barriers formed at the Au-NiO junction accompanying ethanol adsorption and desorption, the spill-over effect and high catalytic activity of Au nanoparticles and the smaller diameter of the particles in the Au-functionalized NiO sensor.

  9. 357 Datation des carbonates impurs au Maroc à l'aide de la ...

    African Journals Online (AJOL)

    youness

    Les résultats isotopiques obtenus montrent que: (1) le Plateau Central. Marocain a connu au moins, deux phases ... déséquilibres radioactifs, spectrométrie alpha, carbonates impurs, travertin, plateau central marocain, Abda- ..... d'oursins et coquilles, et sur la côte atlantique du Haut Atlas au. Maroc, au moyen de coquilles.

  10. Systematic studies of the centrality dependence of soft photon production in Au+Au collision with PHENIX

    CERN Document Server

    Bannier, Benjamin

    2014-01-01

    Since the earliest days of Heavy Ion Physics thermal soft photon radiation emitted during the reaction had been theorized as a smoking gun signal for formation of a quark-gluon plasma and as a tool to characterize its properties. In recent years the existence of excess photon radiation in heavy ion collisions over the expectation from initial hard interactions has been confirmed at both RHIC and LHC energies by PHENIX and ALICE respectively. There the radiation has been found to exhibit elliptic flow $v_2$ well above what can currently be reconciled with a picture of early emission from a plasma phase. During the 2007 and 2010 Au+Au runs PHENIX has measured a high purity sample of soft photons down to $p_T>0.4\\,\\text{GeV}/c$ using an external conversion method. We present recent systematic studies by PHENIX from that sample on the centrality dependence of the soft photon yield, and elliptic and triangular flow $v_2$ and $v_3$ in Au+Au collisions which fill in the experimental picture and enable discrimination...

  11. Effective Dielectric Properties of Au-ZnS and Au-ZnO Plasmonics Nanocomposites in the Terahertz Regime

    Science.gov (United States)

    Zolanvar, A.; Sadeghi, H.; Ranjgar, A.

    2014-10-01

    Composite materials based on plasmonic nanoparticles allow building metamaterials with very large effective permittivity (positive or negative). Moreover, if clustered or combined with other nanoparticles, it is also possible to generate effective magnetic permeability (positive or negative), and an ad-hoc design would result in the generation of double negative materials, and therefore backward wave propagation. In this work, the optical properties such as the effective permittivity, permeability and refractive index of Au-ZnS and Au-ZnO nanocomposites in a broad frequency range are studied. The enhancement is attributed to energy transfer from ZnS or ZnO to Au followed by a large local electromagnetic field on or near the surface of the Au nanoparticles. Local surface plasmon resonance could be the key reason for this enhancement. The surface plasmon, in response to changes in the refractive index of the local environment, also depends on the type of metal through the bulk plasma wavelength and the nano-particle compositions and geometry.

  12. Elevated Temperature Creep Properties of Conventional 50Au-50Cu and 47Au 50Cu-3Ni Braze Alloys

    Energy Technology Data Exchange (ETDEWEB)

    STEPHENS JR.,JOHN J.; SCHMALE,DAVID T.

    2000-12-18

    The elevated temperature creep properties of the 50Au-50Cu wt% and 47Au-50Cu-3Ni braze alloys have been evaluated over the temperature range 250-850 C. At elevated temperatures, i.e., 450-850 C, both alloys were tested in the annealed condition (2 hrs. 750 C/water quenched). The minimum strain rate properties over this temperature range are well fit by the Garofalo sinh equation. At lower temperatures (250 and 350 C), power law equations were found to characterize the data for both alloys. For samples held long periods of time at 375 C (96 hrs.) and slowly cooled to room temperature, an ordering reaction was observed. For the case of the 50Au-50Cu braze alloy, the stress necessary to reach the same, strain rate increased by about 15% above the baseline data. The limited data for ordered 47Au-50Cu-3Ni alloy reflected a,smaller strength increase. However, the sluggishness of this ordering reaction in both alloys does not appear to pose a problem for braze joints cooled at reasonable rates following brazing.

  13. Mettre l'emploi au coeur des priorités au Mexique : étude de cas ...

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

    La recherche empirique sur les rapports entre l'emploi et le développement économique et social au Mexique aidera à repérer les obstacles à une création ... Labour market regulations, particularly minimum wage policies, remain highly contentious and poorly understood issues, both within academic and policy circles.

  14. One pot green synthesis of Ag, Au and Au-Ag alloy nanoparticles using isonicotinic acid hydrazide and starch.

    Science.gov (United States)

    Malathi, Sampath; Ezhilarasu, Tamilarasu; Abiraman, Tamilselvan; Balasubramanian, Sengottuvelan

    2014-10-13

    Gold-silver alloy nanoparticles were synthesized via chemical reduction of varying mole fractions of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) by environmentally benign isonicotinic acid hydrazide (INH) in the presence of starch as a capping agent in aqueous medium. The absorption spectra of Au-Ag nanoparticles show blue shift with increasing silver content indicating the formation of alloy nanoparticles. When the Ag content in the alloy decreases the size of the nanoparticles increases and as a result of which the oxidation potential also increases. The emission maximum undergoes a red shift from 443 to 614 nm. The nanoparticles are monodisperse and spherical with an average particle size of 3-18 nm. The catalytic behavior of alloy nanoparticles indicate that the rate constant for the reduction of 4-nitro phenol to 4-amino phenol increases exponentially from metallic Ag to metallic Au as Au content increases in the Au-Ag alloy nanoparticles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Numerical simulations of high-speed solar wind streams within 1 AU and their signatures at 1 AU

    Science.gov (United States)

    Smith, Z.; Dryer, M.

    1991-01-01

    A parametric study of the evolution within, and signatures at, 1 AU of high-speed streams is performed with the use of a MHD two-and-a-half-dimensional time-dependent model. This study is an extension of an earlier one by Smith and Dryer (1990) who examined the ecliptic plane consequences of relatively short-duration, energetic solar disturbances. The present study examines both the erupting and corotating parts of long-duration, high-speed streams characteristic of coronal hole flows. By examining the variation of the simulated plasma velocity, density, temperature, and magnetic field at 1 AU, as well as the location of the solar coronal hole sources relative to the observer at 1 AU, it was possible to provide some insight into the identification of the solar sources of interplanetary disturbances. Two definitions for angle locating the solar source of interplanetary disturbances at 1 AU are presented and discussed. The results are applied to the suggestion by Hewish (1988) that low-latitude coronal holes are suitably positioned to be the sources of major geomagnetic storms when the holes are in the eastern half of the solar hemisphere at the time of the commencement of the storm. The results indicate that, for these cases, the streams emanating from within the hole must be very fast, greater than 1000 km/s, or very wide, greater than 60 deg, at the inner boundary of 18 solar radii.

  16. Enhanced magneto-plasmonic effect in Au/Co/Au multilayers caused by exciton–plasmon strong coupling

    Energy Technology Data Exchange (ETDEWEB)

    Hamidi, S.M., E-mail: m_hamidi@sbu.ac.ir; Ghaebi, O.

    2016-09-15

    In this paper, we have investigated magneto optical Kerr rotation using the strong coupling of exciton–plasmon. For this purpose, we have demonstrated strong coupling phenomenon using reflectometry measurements. These measurements revealed the formation of two split polaritonic extrema in reflectometry as a function of wavelength. Then we have shown exciton–plasmon coupling in dispersion diagram which presented an anti-crossing between the polaritonic branches. To assure the readers of strong coupling, we have shown an enhanced magneto-optical Kerr rotation by comparing the reflectometry results of strong coupling of surface Plasmon polariton of Au/Co/Au multilayer and R6G excitons with surface Plasmon polariton magneto-optical kerr effect experimental setup. - Highlights: • The magneto optical Kerr rotation has been investigated by using the strong coupling of exciton–plasmon. • We have shown exciton–plasmon coupling in dispersion diagram which presented an anti-crossing between the polaritonic branches. • Strong coupling of surface plasmon polariton and exciton have been yielded to the enhanced magneto-optical Kerr effect. • Plasmons in Au/Co/Au multilayer and exciton in R6G have been coupled to enhance magneto-optical activity.

  17. Energy and system size dependence of phi meson production in Cu+Cu and Au+Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2008-10-28

    We study the beam-energy and system-size dependence of {phi} meson production (using the hadronic decay mode {phi} {yields} K{sup +}K{sup -}) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from midrapidity (|y| < 0.5) for 0.4 < p{sub T} < 5 GeV/c. At a given beam energy, the transverse momentum distributions for {phi} mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The {phi} meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions with a different trend compared to strange baryons. The enhancement for {phi} mesons is observed to be higher at {radical}s{sub NN} = 200 GeV compared to 62.4 GeV. These observations for the produced {phi}(s{bar s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.

  18. Developing an aqueous approach for synthesizing Au and M@Au (M = Pd, CuPt) hybrid nanostars with plasmonic properties

    CERN Document Server

    Du, Jingshan; Xiong, Yalin; Lin, Zhuoqing; Zhang, Hui; Yang, Deren

    2014-01-01

    Anisotropic Au nanoparticles show unique localized surface plasmon resonance (LSPR) properties, which make it attractive in optical, sensing, and biomedical applications. In this contribution, we report a general and facile strategy towards aqueous synthesis of Au and M@Au (M = Pd, CuPt) hybrid nanostars by reducing HAuCl4 with ethanolamine in the presence of cetyltrimethylammonium bromide (CTAB). According to electron microscopic observation and spectral monitoring, we found that the layered epitaxial growth mode (i.e., Frank-van der Merwe mechanism) contributes to the enlargement of the core, while, the random attachment of Au nanoclusters onto the cores accounts for the formation of the branches. Both of them are indispensable for the formation of the nanostars. The LSPR properties of the Au nanoparticles have been well investigated with morphology control via precursor amount and growth temperature. The Au nanostars showed improved surface-enhanced Raman spectroscopy (SERS) performance for rhodamine 6G du...

  19. Application of Turkevich Method for Gold Nanoparticles Synthesis to Fabrication of SiO2@Au and TiO2@Au Core-Shell Nanostructures

    Directory of Open Access Journals (Sweden)

    Paulina Dobrowolska

    2015-05-01

    Full Text Available The Turkevich synthesis method of Au nanoparticles (AuNPs was adopted for direct fabrication of SiO2@Au and TiO2@Au core-shell nanostructures. In this method, chloroauric acid was reduced with trisodium citrate in the presence of amine-functionalized silica or titania submicroparticles. Core-shells obtained in this way were compared to structures fabricated by mixing of Turkevich AuNPs with amine-functionalized silica or titania submicroparticles. It was found that by modification of reaction conditions of the first method, such as temperature and concentration of reagents, control over gold coverage on silicon dioxide particles has been achieved. Described method under certain conditions allows fabrication of semicontinuous gold films on the surface of silicon dioxide particles. To the best of our knowledge, this is the first report describing use of Turkevich method to direct fabrication of TiO2@Au core-shell nanostructures.

  20. Tuning plasmonic and chemical enhancement for SERS detection on graphene-based Au hybrids

    Science.gov (United States)

    Liang, Xiu; Liang, Benliang; Pan, Zhenghui; Lang, Xiufeng; Zhang, Yuegang; Wang, Guangsheng; Yin, Penggang; Guo, Lin

    2015-11-01

    Various graphene-based Au nanocomposites have been developed as surface-enhanced Raman scattering (SERS) substrates recently. However, efficient use of SERS has been impeded by the difficulty of tuning SERS enhancement effects induced from chemical and plasmonic enhancement by different preparation methods of graphene. Herein, we developed graphene-based Au hybrids through physical sputtering gold NPs on monolayer graphene prepared by chemical vapor deposition (CVD) as a CVD-G/Au hybrid, as well as graphene oxide-gold (GO/Au) and reduced-graphene oxide (rGO/Au) hybrids prepared using the chemical in situ crystallization growth method. Plasmonic and chemical enhancements were tuned effectively by simple methods in these as-prepared graphene-based Au systems. SERS performances of CVD-G/Au, rGO/Au and GO/Au showed a gradually monotonic increasing tendency of enhancement factors (EFs) for adsorbed Rhodamine 6G (R6G) molecules, which show clear dependence on chemical bonds between graphene and Au, indicating that the chemical enhancement can be steadily controlled by chemical groups in a graphene-based Au hybrid system. Most notably, we demonstrate that the optimized GO/Au was able to detect biomolecules of adenine, which displayed high sensitivity with a detection limit of 10-7 M as well as good reproducibility and uniformity.Various graphene-based Au nanocomposites have been developed as surface-enhanced Raman scattering (SERS) substrates recently. However, efficient use of SERS has been impeded by the difficulty of tuning SERS enhancement effects induced from chemical and plasmonic enhancement by different preparation methods of graphene. Herein, we developed graphene-based Au hybrids through physical sputtering gold NPs on monolayer graphene prepared by chemical vapor deposition (CVD) as a CVD-G/Au hybrid, as well as graphene oxide-gold (GO/Au) and reduced-graphene oxide (rGO/Au) hybrids prepared using the chemical in situ crystallization growth method. Plasmonic