WorldWideScience

Sample records for compositionally zoned sulfide

  1. Chemistry, isotopic composition, and origin of a methane-hydrogen sulfide hydrate at the Cascadia subduction zone

    Science.gov (United States)

    Kastner, M.; Kvenvolden, K.A.; Lorenson, T.D.

    1998-01-01

    Although the presence of extensive gas hydrate on the Cascadia margin, offshore from the western U.S. and Canada, has been inferred from marine seismic records and pore water chemistry, solid gas hydrate has only been found at one location. At Ocean Drilling Program (ODP) Site 892, offshore from central Oregon, gas hydrate was recovered close to the sediment - water interface at 2-19 m below the seafloor, (mbsf) at 670 m water depth. The gas hydrate occurs as elongated platy crystals or crystal aggregates, mostly disseminated irregularly, with higher concentrations occurring in discrete zones, thin layers, and/or veinlets parallel or oblique to the bedding. A 2-to 3-cm thick massive gas hydrate layer, parallel to bedding, was recovered at ???17 mbsf. Gas from a sample of this layer was composed of both CH4 and H2S. This sample is the first mixed-gas hydrate of CH4-H2S documented in ODP; it also contains ethane and minor amounts of CO2. Measured temperature of the recovered core ranged from 2 to - 18??C and are 6 to 8 degrees lower than in-situ temperatures. These temperature anomalies were caused by the partial dissociation of the CH4-H2S hydrate during recovery without a pressure core sampler. During this dissociation, toxic levels of H2S (??34S, +27.4???) were released. The ??13C values of the CH4 in the gas hydrate, -64.5 to -67.5???(PDB), together with ??D values of - 197 to - 199???(SMOW) indicate a primarily microbial source for the CH4. The ??18O value of the hydrate H2O is +2.9???(SMOW), comparable with the experimental fractionation factor for sea-ice. The unusual composition (CH4-H2S) and depth distribution (2-19 mbsf) of this gas hydrate indicate mixing between a methane-rich fluid with a pore fluid enriched in sulfide; at this site the former is advecting along an inclined fault into the active sulfate reduction zone. The facts that the CH4-H2S hydrate is primarily confined to the present day active sulfate reduction zone (2-19 mbsf), and that from here

  2. Partition coefficients for Ni, Cu, Pd, Pt, Rh, and Ir between monosulfide solid solution and sulfide liquid and the formation of compositionally zoned Ni-Cu sulfide bodies by fractional crystallization of sulfide liquid

    DEFF Research Database (Denmark)

    Barnes, S.J.; Makovicky, E.; Makovicky, M.

    1996-01-01

    Many nickel–copper sulfide orebodies contain Cu- and Fe-rich portions. The Fe-rich ore is generally richer in Os, Ir, Ru, and Rh and poorer in Pt, Pd, and Au than the Cu-rich ore. In komatiite-hosted ores Ni tends to be concentrated in the Cu-rich ore, whereas in tholeiitic ores it tends to be co...

  3. Diamond growth history from in situ measurement of Pb and S isotopic compositions of sulfide inclusions

    Science.gov (United States)

    Rudnick, Roberta L.; Eldridge, C. Stewart; Bulanova, Galina P.

    1993-01-01

    In a continuing effort to understand crust-mantle dynamics, we have determined the S and Pb isotopic compositions of mantle sulfides encapsulated within diamonds from under the Siberian craton and compared these results to those of previously investigated African counterparts. Because diamond inclusions are isolated from exchange with surrounding mantle, they may preserve the history of diamond growth and act as direct tracers of the origins of mantle materials. Study of these inclusions may thus offer the best chance of recognizing global-scale interaction between Earth's crust and mantle. Although δ34S values of the Siberian sulfides do not deviate significantly from the mantle value of 0‰ ± 3‰, Pb isotopic compositions are highly variable. Pb isotopic compositions of sulfides from peridotitic suite diamonds generally plot near the terrestrial Pb growth curve, with model ages ranging between 0 and 2 Ga, whereas sulfides from eclogitic suite diamonds have radiogenic compositions, plotting beyond the growth curve. These results, which are similar to those for sulfides in African diamonds, suggest that the sulfides from eclogitic suite diamonds were derived from a source with an unusually high U/Pb ratio and may indicate a common process (such as subduction of crystal materials into the mantle) operating beneath Africa and Siberia. The absence of extremely radiogenic Pb in sulfides from eclogite xenoliths suggests that the radiogenic material from which eclogitic suite diamonds grew was a transient feature of the mantle, associated with diamond growth. The ultimate origin of this high U/Pb signature, however, remains enigmatic. Large variations in Pb isotopic composition of sulfides from different zones in a single peridotitic suite diamond document (1) crystallization of the diamond's core near 2.0 Ga, (2) growth of its outer zone in an environment with a high U/Pb ratio similar to the growth environment of eclogitic suite diamonds, and (3) growth of the

  4. EFFECTS OF SYNTHESIS TEMPERATURE ON PHASE COMPOSITION OF MAGNESIUM SULFIDE SYNTHESIZED BY THE TWO-ZONE FURNACE METHOD%合成温度对双温区合成硫化镁相组成的影响

    Institute of Scientific and Technical Information of China (English)

    刘涛; 李琳; 于景坤

    2009-01-01

    以金属镁和升华硫为原料,采用双温区反应炉合成了MgS,合成的MgS产量高且工艺安全.利用X射线衍射分析了合成产物的相组成,考察了合成温度(θh和θ1)对合成体系和相组成的影响.研究了合成体系内升华硫的蒸发量与合成体系容积大小、合成温度以及合成体系抗压强度等参数间的关系.结果表明:合成体系内的最大升华硫蒸发量应小于2.45 g,θh和θ1明显影响合成产物的相组成,随着θh和θ1和保温时间的提高,MgS衍射峰强度逐渐增大,反应进行得更加充分.反应的最佳工艺参数;θh为1000℃,θ1为100℃,保温时间为32h.%A large amount of magnesium sulfide was synthesized safely with a two-zone furnace method by using magnesium metal and sublimed sulfur as raw materials. The phase composition of the products was identified by X-ray diffraction. The influences of the synthesis temperature (θh and θ1) on the synthesis system and the phase composition were investigated. The relationships among the maximum amount of gaseous sulfur, the volume of the quartz tube, the synthesis temperature and the pressure in the quartz tube were studied. The results indicate that the maximum amount of gaseous sulfur in the quartz tube must be less than 2.45 g. The θh and θ1 have an obvious effect on the phase composition of the products. With the increase of θh and θ1, the intensity of the diffraction peaks of MgS increase gradually and the reaction proceeds more adequately. The optimum process parameters are a θh of 1 000 ℃, a θ1 of 100 ℃, and a holding time of 32 h.

  5. High conducting oxide--sulfide composite lithium superionic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chengdu; Rangasamy, Ezhiylmurugan; Dudney, Nancy J.; Keum, Jong Kahk; Rondinone, Adam Justin

    2017-01-17

    A solid electrolyte for a lithium-sulfur battery includes particles of a lithium ion conducting oxide composition embedded within a lithium ion conducting sulfide composition. The lithium ion conducting oxide composition can be Li.sub.7La.sub.3Zr.sub.2O.sub.12 (LLZO). The lithium ion conducting sulfide composition can be .beta.-Li.sub.3PS.sub.4 (LPS). A lithium ion battery and a method of making a solid electrolyte for a lithium ion battery are also disclosed.

  6. Benzothiazole sulfide compatibilized polypropylene/halloysite nanotubes composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu Mingxian [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China); Guo Baochun, E-mail: psbcguo@scut.edu.cn [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China); Lei Yanda; Du Mingliang; Jia Demin [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2009-02-15

    Clay-philic benzothiazole sulfide, capable of donating electrons, is grafted onto polypropylene (PP) backbones when N-cyclohexyl-2-benzothiazole sulfonamide (CBS), a commonly used accelerator in the tire industry, is included in the processing of PP/halloysite nanotubes (HNTs) composites. CBS decomposes at elevated temperature and yields benzothiazole sulfide radicals, which react with the PP polymeric free radicals generated during the processing of the composites. On the other hand, the benzothiazole group of CBS is reactive to HNTs via electron transferring. The compatibilization between HNTs and PP is thus realized via interfacial grafting and electron transferring mechanism. The interfacial interactions in the compatibilized systems were fully characterized. Compared with the control sample, the dispersion of HNTs and the interfacial bonding are enhanced substantially in the compatibilized composites. The significantly improved mechanical properties and thermal properties of benzothiazole sulfide compatibilized PP/HNTs composites are correlated to the enhanced interfacial property. The present work demonstrates a novel interfacial design via interfacial grafting/electron transferring for the compatibilization of PP/clay composites.

  7. Mineral systems and the thermodynamics of selenites and selenates in the oxidation zone of sulfide ores - a review

    Science.gov (United States)

    Charykova, Marina V.; Krivovichev, Vladimir G.

    2016-08-01

    Contemporary mineralogy and geochemistry are concerned with understanding and deciphering processes that occur near the surface of the Earth. These processes are especially important for resolving ecological challenges and developing principles of good environmental management. Selenium oxysalts, selenites and selenates, are relatively rare as minerals; there are presently only 34 known mineral species. Thirty-one "pure" selenites, which contain only selenite anionic groups, are known to occur naturally. The other three minerals each contain two anionic groups: selenate and selenite (schmiederite), selenate and sulphate (olsacherite), and selenate and iodate (carlosruizite). This work is intended to provide a classification of natural selenium oxysalts based on their chemical composition. Selenites belong to a particular mineral system, whose components are chemical elements required to construct the crystal structure of a mineral (species-defining constituents). The number of components represents the minimum number of independent elements necessary to define the composition of the system. All selenites and selenates are divided into two groups: anhydrous selenites (I) and hydrous selenites and selenates (II). The paper also presents systematized data published on the thermodynamics of selenites, which are formed in the weathering zone of sulfide and selenide ores, and determines approaches to the quantitative physicochemical modeling of formation conditions. The Eh-pH diagrams of the Me-Se-H2O systems (Me = Cu, Co, Ni, Fe, Zn, Ca, Al) were calculated and plotted for the average contents of these elements in aqueous weathering solutions in sulfide deposit oxidation zones.

  8. Microbial sulfide oxidation in the oxic–anoxic transition zone of freshwater sediment: involvement of lithoautotrophic Magnetospirillum strain J10

    NARCIS (Netherlands)

    Geelhoed, J.S.; Sorokin, D.; Epping, E.; Tourova, T.P.; Banciu, H.L.; Muyzer, G.; Stams, A.J.M.; Loosdrecht, van M.C.

    2009-01-01

    The oxic-anoxic transition zone (OATZ) of freshwater sediments, where opposing gradients exist of reduced iron and sulfide with oxygen, creates a suitable environment for microorganisms that derive energy from the oxidation of iron or sulfide. Gradient microcosms incubated with freshwater sediment

  9. Giant hydrogen sulfide plume in the oxygen minimum zone off Peru supports chemolithoautotrophy.

    Directory of Open Access Journals (Sweden)

    Harald Schunck

    Full Text Available In Eastern Boundary Upwelling Systems nutrient-rich waters are transported to the ocean surface, fuelling high photoautotrophic primary production. Subsequent heterotrophic decomposition of the produced biomass increases the oxygen-depletion at intermediate water depths, which can result in the formation of oxygen minimum zones (OMZ. OMZs can sporadically accumulate hydrogen sulfide (H2S, which is toxic to most multicellular organisms and has been implicated in massive fish kills. During a cruise to the OMZ off Peru in January 2009 we found a sulfidic plume in continental shelf waters, covering an area >5500 km(2, which contained ∼2.2×10(4 tons of H2S. This was the first time that H2S was measured in the Peruvian OMZ and with ∼440 km(3 the largest plume ever reported for oceanic waters. We assessed the phylogenetic and functional diversity of the inhabiting microbial community by high-throughput sequencing of DNA and RNA, while its metabolic activity was determined with rate measurements of carbon fixation and nitrogen transformation processes. The waters were dominated by several distinct γ-, δ- and ε-proteobacterial taxa associated with either sulfur oxidation or sulfate reduction. Our results suggest that these chemolithoautotrophic bacteria utilized several oxidants (oxygen, nitrate, nitrite, nitric oxide and nitrous oxide to detoxify the sulfidic waters well below the oxic surface. The chemolithoautotrophic activity at our sampling site led to high rates of dark carbon fixation. Assuming that these chemolithoautotrophic rates were maintained throughout the sulfidic waters, they could be representing as much as ∼30% of the photoautotrophic carbon fixation. Postulated changes such as eutrophication and global warming, which lead to an expansion and intensification of OMZs, might also increase the frequency of sulfidic waters. We suggest that the chemolithoautotrophically fixed carbon may be involved in a negative feedback loop that

  10. Influence of sulfides on the tribological properties of composites produced by pulse electric current sintering

    Institute of Scientific and Technical Information of China (English)

    Seung Ho Kim

    2014-01-01

    Self-lubricating Al2O3-15wt%ZrO2 composites with sulfides, such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) serving as solid lubricants, were fabricated by using the pulse electric current sintering (PECS) technique. The coefficient of friction (COF) of the Al2O3-15wt%ZrO2 composite without/with sulfides was in the range of 0.37-0.48 and 0.27-0.49, respectively. As the amount of sul-fides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.

  11. On the existence of free and metal complexed sulfide in the Arabian Sea and its oxygen minimum zone

    Science.gov (United States)

    Theberge, Stephen M.; Luther, George W.; Farrenkopf, Anna M.

    Free hydrogen sulfide was not detected in the oxygen minimum zone (OMZ) of the Arabian Sea during legs D1 (September 1992) and D3 (October-November 1992) of the Netherlands Indian Ocean Programme (NIOP). However, sulfide complexed to metals was detected by cathodic stripping square wave voltammetry at 2 nM or less throughout the water column. A slight increase in sulfide was measured in the OMZ relative to the surface waters and may be related to sulfur release from organic matter during decomposition. Sulfide complexes are of two general types at low concentrations of metal and sulfide. First, metals such as Mn, Fe, Co and Ni form complexes with bisulfide ion (HS -) that are kinetically labile to dissociation and are reactive. Second, metals such as Cu and Zn form multinuclear complexes with sulfide (S 2-) that are kinetically inert to dissociation; thus, they are less reactive than free (bi)sulfide and the labile metal bisulfide complexes. Zinc and copper sulfide complexes are important in allowing hydrogen sulfide to persist in seawater which contains measurable oxygen.

  12. Regulation of bacterial sulfate reduction and hydrogen sulfide fluxes in the central Namibian coastal upwelling zone

    DEFF Research Database (Denmark)

    Bruchert, V.; Jørgensen, BB; Neumann, K.;

    2003-01-01

    and the low capacity to oxidize and trap sulfide. The inner shelf break marks the seaward border of sulfidic bottom waters, and separates two different regimes of bacterial sulfate reduction. In the sulfidic bottom waters on the shelf, up to 55% of sulfide oxidation is mediated by the large nitrate...... to the sediment-water interface and reduce the hydrogen sulfide flux to the water column. Modeling of pore water sulfide concentration profiles indicates that sulfide produced by bacterial sulfate reduction in the uppermost 16 cm of sediment is sufficient to account for the total flux of hydrogen sulfide...... to the water column. However, the total pool of hydrogen sulfide in the water column is too large to be explained by steady state diffusion across the sediment-water interface. Episodic advection of hydrogen sulfide, possibly triggered by methane eruptions, may contribute to hydrogen sulfide in the water...

  13. Electrically Conducting Polymer-Copper Sulphide Composite Films, Preparation by Treatment of Polymer-Copper (2) Acetate Composites with Hydrogen Sulfide

    Science.gov (United States)

    Yamamoto, Takakazu; Kamigaki, Takahira; Kubota, Etsuo

    1988-01-01

    Polymer copper sulfide composite films were prepared by treatment of polymer poly(vinyl chloride), poly(acrylonitrile), copolymer of vinyl chloride and vinyl acetate (90:10), and ABS resin copper (2) acetate composites with hydrogen sulfide. The films showed electrical conductivity higher than 0.015 S/cm when they contained more than 20 wt percent of copper sulfide. A poly(acrylonitrile)-copper sulfide composite film containing 40 to 50 wt percent of copper sulfide showed electrical conductivity of 10 to 150.0 S/cm and had relatively high mechanical strength to be used in practical purposes.

  14. Compositional zoning of the bishop tuff

    Science.gov (United States)

    Hildreth, W.; Wilson, C.J.N.

    2007-01-01

    Compositional data for >400 pumice clasts, organized according to eruptive sequence, crystal content, and texture, provide new perspectives on eruption and pre-eruptive evolution of the >4600 km3 of zoned rhyolitic magma ejected as the BishopTuff during formation of Long Valley caldera. Proportions and compositions of different pumice types are given for each ignimbrite package and for the intercalated plinian pumice-fall layers that erupted synchronously. Although withdrawal of the zoned magma was less systematic than previously realized, the overall sequence displays trends toward greater proportions of less evolved pumice, more crystals (0-5 24 wt %), and higher FeTi-oxide temperatures (714-818??C). No significant hiatus took place during the 6 day eruption of the BishopTuff, nearly all of which issued from an integrated, zoned, unitary reservoir. Shortly before eruption, however, the zoned melt-dominant portion of the chamber was invaded by batches of disparate lower-silica rhyolite magma, poorer in crystals than most of the resident magma but slightly hotter and richer in Ba, Sr, andTi. Interaction with resident magma at the deepest levels tapped promoted growth ofTi-rich rims on quartz, Ba-rich rims on sanidine, and entrapment of near-rim melt inclusions relatively enriched in Ba and CO2.Varied amounts of mingling, even in higher parts of the chamber, led to the dark gray and swirly crystal-poor pumices sparsely present in all ashflow packages. As shown by FeTi-oxide geothermometry, the zoned rhyolitic chamber was hottest where crystal-richest, rendering any model of solidification fronts at the walls or roof unlikely.The main compositional gradient (75-195 ppm Rb; 0.8-2.2 ppm Ta; 71-154 ppm Zr; 0.40-1.73% FeO*) existed in the melt, prior to crystallization of the phenocryst suite observed, which included zircon as much as 100 kyr older than the eruption.The compositions of crystals, though themselves largely unzoned, generally reflect magma temperature and

  15. Sulfide Composition and Melt Stability Field in the Earth's Upper Mantle

    Science.gov (United States)

    Zhang, Z.; Hirschmann, M. M.

    2015-12-01

    In the Earth's upper mantle, sulfur occurs chiefly as (Fe, Ni)xS minerals and melts with near-monosulfide stoichiometries. These could have substantial influence on geochemical and geophysical properties of the Earth's interior. For example, sulfide mineral and melts are the major carriers of chalcophile and platinum group elements (PGEs) and sulfide melts are potentially responsible for mantle geophysical anomalies, as their physical properties (higher density, surface tension, electrical conductivity and lower melting points) differ greatly from those of silicates. Sulfide melts are a potential sink for reduced mantle carbon and perhaps be associated with carbon transport, including diamond precipitation. Sulfides may be molten in large parts of the mantle, but this is determined in part by sulfide composition, which is in turn a product of Fe-Ni exchange with olivine and of the effect of sulfur, oxygen, and carbon fugacities on metal/anion ratios of melts. Melting experiments define the monosulfide (Fe0.35Ni0.12Cu0.01S0.52) solidus from 1-8 GPa at carbon-free and graphite saturated conditions. The resulting carbon-free solidus is below the mantle adiabat to depths of at least 300 km, but does not indicate sulfide melting in continental lithosphere. In contrast, the graphite saturated solidus indicates melting in the lithosphere at 6-7 GPa (~200 km), close to the source conditions typical of diamond formation. To determine the composition of sulfide equilibrated with olivine, we performed experiments on monosulfide-olivine (crushed powders from San Carlos single crystal) under 2 GPa, 1400 ◦C. Our preliminary results suggests that Fe-Ni distribution coefficients KD, defined by (Ni/Fe)sulfide/(Ni/Fe)olivine, have significantly lower values than those determined previously at one atmosphere (Doyle and Naldrett 1987; Fleet and MacRae 1987; Gaetani and Grove 1997). This indicates that sulfide equilibrated with olivine in the mantle is richer in Fe than former

  16. Lithium sulfide compositions for battery electrolyte and battery electrode coatings

    Science.gov (United States)

    Liang, Chengdu; Liu, Zengcai; Fu, Wunjun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J

    2013-12-03

    Methods of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electroytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one or .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.

  17. Electrochemical properties of tungsten sulfide-carbon composite microspheres prepared by spray pyrolysis.

    Science.gov (United States)

    Choi, Seung Ho; Boo, Sung Jin; Lee, Jong-Heun; Kang, Yun Chan

    2014-01-01

    Tungsten sulfide (WS2)-carbon composite powders with superior electrochemical properties are prepared by a two-step process. WO3-carbon composite powders were first prepared by conventional spray pyrolysis, and they were then sulfidated to form WS2-carbon powders. Bare WS2 powders are also prepared by sulfidation of bare WO3 powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS2 and WS2-carbon composite powders. The amorphous bare WS2 and WS2-carbon composite powders have Brunauer-Emmett-Teller (BET) surface areas of 2.8 and 4 m(2) g(-1), respectively. The initial discharge and charge capacities of the WS2-carbon composite powders at a current density of 100 mA g(-1) are 1055 and 714 mA h g(-1), respectively, and the corresponding initial Coulombic efficiency is 68%. On the other hand, the initial discharge and charge capacities of the bare WS2 powders are 514 and 346 mA h g(-1), respectively. The discharge capacities of the WS2-carbon composite powders for the 2(nd) and 50(th) cycles are 716 and 555 mA h g(-1), respectively, and the corresponding capacity retention measured after first cycle is 78%.

  18. Hydrogen sulfide adsorption on MOFs and MOF/graphite oxide composites.

    Science.gov (United States)

    Petit, Camille; Mendoza, Barbara; Bandosz, Teresa J

    2010-12-03

    Composites of a copper-based metal-organic framework (MOF) and graphite oxide (GO) were tested for hydrogen sulfide removal at ambient conditions. In order to understand the mechanisms of adsorption, the initial and exhausted samples were analyzed by various techniques including X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analyses, and sorption of nitrogen. Compared to the parent materials, an enhancement in hydrogen sulfide adsorption was found. It was the result of physical adsorption of water and H(2)S in the pore space formed at the interface between the MOF units and the graphene layers where the dispersive forces are the strongest. Besides physisorption, reactive adsorption was found as the main mechanism of retention. H(2)S molecules bind to the copper centers of the MOF. They progressively react with the MOF units resulting in the formation of copper sulfide. This leads to the collapse of the MOF structure. Water enhances adsorption in the composites as it allows the dissolution of hydrogen sulfide.

  19. Tellurium-bearing minerals in zoned sulfide chimneys from Cu-Zn massive sulfide deposits of the Urals, Russia

    Science.gov (United States)

    Maslennikov, V. V.; Maslennikova, S. P.; Large, R. R.; Danyushevsky, L. V.; Herrington, R. J.; Stanley, C. J.

    2013-02-01

    Tellurium-bearing minerals are generally rare in chimney material from mafic and bimodal felsic volcanic hosted massive sulfide (VMS) deposits, but are abundant in chimneys of the Urals VMS deposits located within Silurian and Devonian bimodal mafic sequences. High physicochemical gradients during chimney growth result in a wide range of telluride and sulfoarsenide assemblages including a variety of Cu-Ag-Te-S and Ag-Pb-Bi-Te solid solution series and tellurium sulfosalts. A change in chimney types from Fe-Cu to Cu-Zn-Fe to Zn-Cu is accompanied by gradual replacement of abundant Fe-, Co, Bi-, and Pb- tellurides by Hg, Ag, Au-Ag telluride and galena-fahlore with native gold assemblages. Decreasing amounts of pyrite, both colloform and pseudomorphic after pyrrhotite, isocubanite ISS and chalcopyrite in the chimneys is coupled with increasing amounts of sphalerite, quatz, barite or talc contents. This trend represents a transition from low- to high sulphidation conditions, and it is observed across a range of the Urals deposits from bimodal mafic- to bimodal felsic-hosted types: Yaman-Kasy → Molodezhnoye → Uzelga → Valentorskoye → Oktyabrskoye → Alexandrinskoye → Tash-Tau → Jusa.

  20. Decomposition kinetic study of nanostructured composites of poly (phenylene sulfide) reinforced with carbon nanotubes

    OpenAIRE

    Bruno Ribeiro; Edson C. Botelho; Michelle L. Costa

    2014-01-01

    The aim of this work is to obtain nanostructured composites of poly (phenylene sulfide), PPS, reinforced with multiwalled carbon nanotubes, MWCNT, by melt mixing technique and further characterization of their morphological and thermal properties. Transmission Electron Microscopy analysis was carried out to evaluate the quality of MWCNT dispersion throughout the PPS matrix. Thermogravimetry shows an increase in the maximum degradation temperature by the addition of the nanofiller to the polym...

  1. Cu-Ni-PGE fertility of the Yoko-Dovyren layered massif (northern Transbaikalia, Russia): thermodynamic modeling of sulfide compositions in low mineralized dunite based on quantitative sulfide mineralogy

    Science.gov (United States)

    Ariskin, Alexey A.; Kislov, Evgeny V.; Danyushevsky, Leonid V.; Nikolaev, Georgy S.; Fiorentini, Marco L.; Gilbert, Sarah; Goemann, Karsten; Malyshev, Alexey

    2016-12-01

    The geology and major types of sulfide mineralization in the Yoko-Dovyren layered massif (northern Transbaikalia, Russia) are presented. This study focuses on the structure, mineralogy, and geochemistry of poorly mineralized plagiodunite and dunite in the lower part of the intrusion. Assuming these rocks contain key information on the timing of sulfide immiscibility in the original cumulate pile, we apply a novel approach which combines estimates of the average sulfide compositions in each particular rock with thermodynamic modeling of the geochemistry of the original sulfide liquid. To approach the goal, an updated sulfide version of the COMAGMAT-5 model was used. Results of simulations of sulfide immiscibility in initially S-undersaturated olivine cumulates demonstrate a strong effect of the decreasing fraction of the silicate melt, due to crystallization of silicate and oxide minerals, on the composition of the intercumulus sulfide liquid. Comparison of the observed and modeled sulfide compositions indicates that the proposed modeling reproduces well the average concentrations of Cu, Cd, Ag, and Pd in natural sulfides. This suggests the sulfide control on the distribution of these elements in the rocks. Conversely, data for Pt and Au suggest that a significant portion of these elements could present in a native form, thus depleting the intercumulus sulfide melt at an early stage of crystallization.

  2. Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    关耀辉

    2006-01-01

    Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying (APS). The microstructure and phase composition of the coating were characterized with SEM and XRD, respectively. In addition, the size distribution of the reconstituted powders and the porosity of the coating have been measured. It was found that the reconstitiuted powers with sizes in the range of 20 to 80 μm had excellent flowability and were suitable for plasma spraying process. The assprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains (30~80nm) and large grains (100~200nm). The coating was mainly composed of FeS and SiC, a small quantity of Fe1-x S and oxide were also found. The porosity of the coating was approximately 19 %.

  3. A high conductivity oxide–sulfide composite lithium superionic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Rangasamy, Ezhiylmurugan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Sahu, Gayatri [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Keum, Jong Kahk [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Rondinone, Adam J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Dudney, Nancy J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Liang, Chengdu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2014-01-14

    We fabricated a hybrid superionic conductor using the space charge effect between the LLZO and LPS interfaces. This space-charge effect resulted in an improvement over the individual bulk conductivities of the two systems. Sample with higher weight fractions of LLZO are limited by the porosity and grain boundary resistance arising from non-sintered membranes. Furthermore, by combining the properties of LLZO and LPS, the high temperature sintering step has been avoided thus facilitating easier materials processing. The interfacial resistances were also measured to be minimal at ambient conditions. Our procedure thus opens a new avenue for improving the ionic conductivity and electrochemical properties of existing solid state electrolytes. High frequency impedance analyses could aid in resolving the ionic conductivity contributions from the space charge layer in the higher conducting composites while mechanical property investigations could illustrate an improvement in the composite electrolyte in comparison with the crystalline LPS membranes.

  4. Flower-Like Beta-Cobalt Sulfide Microsphere and Activated Carbon/Cobalt Sulfide Composites for Capacitive Deionization

    Science.gov (United States)

    Wu, Xuechen

    Capacitive deionization (CDI) is an emerging technology for water desalination via facile removal of charged ionic species from aqueous solutions. The mechanism of CDI is based on ion adsorption by forming electric double layers at the electrode/electrolyte interface or conducting the reversible faradaic reaction at/near the electrode surface. Thus, electrode materials can significantly affect the CDI performance. Cobalt sulfide with demonstrated supercapacitor performance shows great potential for CDI electrode. In this thesis, flower-like beta-cobalt sulfide (CoS1.097) were successfully synthesized through hydrothermal reaction. It has been demonstrated that the morphology and structure of CoS 1.097 are greatly influenced by hydrothermal temperature. The sample of CoS1.097 synthesized at 140°C for 8 h exhibited the best electrochemical performance with a maximum specific capacity of 121 F/g at the current density of 0.2 A/g in 1M NaCl aqueous solution. However, further improvement of electrosorption capacity was constricted by poor conductivity and low surface area of CoS1.097. Therefore, the combination of activated carbon (AC) and CoS1.097 seems to be a feasible strategy by utilizing the high electrochemical activity of CoS1.097 and the high conductivity and the large surface area of AC. Herein, AC/CoS 1.097 composites were constructed by hydrothermal method and hot plate method, respectively. Hot plate AC/CoS1.097 possessed a specific capacity of 260 F/g at 0.2 A/g in 1M NaCl solution, which was higher than that of hydrothermal AC/CoS1.097 (197 F/g). It may be attributed to the excellent synergistic combination and the smaller size CoS1.097 particles of hot plate AC/CoS1.097. In addition, hot plate AC/CoS1.097 can reach a maximum electrosorption capacity of 3.1 mg/g at 1.2 V in 28 ml of 100 mg/l NaCl solution in flow-type CDI cell, which makes it a suitable electrode material for large-scale CDI application.

  5. Trace element composition of olivine - implications for the evolution of the olivine gabbro-troctolite-hosted Voisey's Bay Ni-Cu-Co sulfide deposit, Labrador

    Science.gov (United States)

    Bulle, F.; Layne, G. D.

    2011-12-01

    The Mesoproterozoic Voisey's Bay intrusion is part of the Nain Plutonic Suite, which transects the 1.85 Ga collisional boundary between the Proterozoic Churchill Province and the Archean Nain Province in Eastern Labrador. The intrusion comprises a group of troctolitic to olivine gabbroic bodies linked by olivine gabbro dikes; together these rocks host the world-class Voisey's Bay Ni-Cu-Co sulfide deposit. Zones of massive and disseminated sulfide mineralization (Reid Brook, Discovery Hill, Mini-Ovoid and Ovoid) occur within a dike and at the entry line of this dike into a larger intrusion termed the Eastern Deeps [1, 2, 3]. At least two pulses of magma have generated the intrusion and the associated sulfide mineralization; an initial surge that achieved sulfide saturation by interacting with upper crustal rocks, and a later pulse of fresh, undepleted magma that forced the initial magma upwards and both remobilized the immiscible sulfide liquid and upgraded it in metal content [1, 2, 3]. Previous research [1, 2] has shown that the Ni content of olivine from the distinct sulfide-bearing host rocks is highly variable, and also indicative of both magma mixing and interaction of silicate magmas with sulfide. To further validate the significance of the olivine chemistry as a tracer for ore-forming petrological processes, we have determined the abundances of Cr, Mn, Co, Ni, Zn in olivines from the various mafic lithologies of the Eastern Deeps intrusion using Secondary Ion Mass Spectrometry. We present systematic variations in Mn, Co, Ni and Zn with Fo-content in olivines for both sulfide-free and sulfide-bearing zones. Olivines from mineralized and brecciated troctolitic/gabbroic zones display significantly higher Mn (up to 11,000 ppm) and Zn (up to 550 ppm) concentrations than those from nominally barren counterparts. The barren troctolite, broadly termed normal troctolite (NT), is a petrographically homogenous plagioclase and olivine cumulate. However, olivine

  6. The influence of the silicate slag composition on copper losses during smelting of the sulfide concentrates

    Directory of Open Access Journals (Sweden)

    Živković Živan

    2009-01-01

    Full Text Available This paper presents the results of multi-linear regression analysis (MLRA of the slag composition (SiO2, FeO, Fe3O4, CaO, Al2O3 and the content of copper in the matte on resulting copper content in the slag during smelting of the sulfide concentrates in the reverberatory furnace. When comparing results obtained with MLRA model calculations with values measured at industrial level high degree of fitting is obtained (R2 = 0.974. This indicates that slag composition and content of copper in the matte influences the copper losses in the waste slag with the probability of 95 %.

  7. The influence of the silicate slag composition on copper losses during smelting of the sulfide concentrates

    OpenAIRE

    2009-01-01

    This paper presents the results of multi-linear regression analysis (MLRA) of the slag composition (SiO2, FeO, Fe3O4, CaO, Al2O3) and the content of copper in the matte on resulting copper content in the slag during smelting of the sulfide concentrates in the reverberatory furnace. When comparing results obtained with MLRA model calculations with values measured at industrial level high degree of fitting is obtained (R2 = 0.974). This indicates that slag composition and content of copper in t...

  8. The composition and temperature dependence of the sulfide capacity of metallurgical slags

    Science.gov (United States)

    Sosinsky, Nd. J.; Sommerville, I. D.

    1986-06-01

    The concept of optical basicity and its applicability as a means of correlating the available data on the sulfide capacity of metallurgical slags has been reviewed. An excellent correlation based on very extensive data at 1500 °C, which was discussed in a previous paper, is combined with good correlations based on considerably less data at 1550 °C and 1650 °C to quantify the effect of temperature on the sulfide capacity of slags. The combined effects of slag composition and temperature have been expressed in the equation, log C s = [(22690 - 54640A)/7] + 43.6A - 25.2. Use of this equation permits the calculation of the sulfide capacity of a slag at any temperature between 1400 °C and 1700 °C simply from a knowledge of its chemical composition, and can be employed for virtually any oxide slag of interest in the field of iron and steelmaking. This, in turn, permits calculation of the equilibrium distribution of sulfur between this slag and iron or steel, provided that the oxygen potential is known or can be calculated from the degree of deoxidation applied.

  9. Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

    Science.gov (United States)

    Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D.; Joslin, G.D.

    2008-01-01

    Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

  10. Iron sulfide (troilite) inclusion extracted from Sikhote-Alin iron meteorite: Composition, structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M.I., E-mail: oshtrakh@gmail.com [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Klencsár, Z. [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117 (Hungary); Petrova, E.V.; Grokhovsky, V.I. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Chukin, A.V. [Department of Theoretical Physics and Applied Mathematics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Shtoltz, A.K. [Department of Electrophysics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Maksimova, A.A. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Felner, I. [Racah Institute of Physics, The Hebrew University, Jerusalem (Israel); Kuzmann, E.; Homonnay, Z. [Institute of Chemistry, Eötvös Loránd University, Budapest (Hungary); Semionkin, V.A. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation)

    2016-05-01

    Iron sulfide (troilite) inclusion extracted from Sikhote-Alin IIAB iron meteorite was examined for its composition, structure and magnetic properties by means of several complementary analytical techniques such as: powder X-ray diffractometry, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, magnetization measurements, ferromagnetic resonance spectroscopy and {sup 57}Fe Mössbauer spectroscopy with a high velocity resolution. The applied techniques consistently indicated the presence of daubréelite (FeCr{sub 2}S{sub 4}) as a minority phase beside troilite proper (FeS). As revealed by {sup 57}Fe Mössbauer spectroscopy, the Fe atoms in troilite were in different microenvironments associated with either the ideal FeS structure or that of a slightly iron deficient Fe{sub 1–x}S. Phase transitions of troilite were detected above room temperature by ferromagnetic resonance spectroscopy. A novel analysis of 295 and 90 K {sup 57}Fe Mössbauer spectra was carried out and the hyperfine parameters associated with the ideal structure of troilite were determined by considering the orientation of the hyperfine magnetic field in the eigensystem of the electric field gradient at the {sup 57}Fe nucleus. - Highlights: • The presence of daubréelite in iron sulfide inclusion in Sikhote-Alin iron meteorite. • The presence of the ideal FeS and iron deficient Fe{sub 1–x}S in iron sulfide inclusion. • New way of the iron sulfide Mössbauer spectrum approximation.

  11. Normal zone propagation in adiabatic superconducting magnets: Pt. 1; Normal zone propagation velocity in superconducting composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z.P.; Iwasa, Y. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab. Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)

    1991-09-01

    A normal zone propagation model has been developed for superconducting composites under adiabatic conditions. It is based on the Whetstone-Roos model, originally developed for normal zone propagation in adiabatic wires of unclad superconductor. The model takes into account the temperature and magnetic field dependent material properties, for both superconductor and matrix metal. Analytical results agree well with experimental data. (author).

  12. Electrochemiluminescence of a nanoAg-carbon nanodot composite and its application to detect sulfide ions.

    Science.gov (United States)

    Wang, Zhong-Xia; Zheng, Chun-Lan; Li, Qi-Le; Ding, Shou-Nian

    2014-04-07

    This work presents the enhanced electrochemiluminescence (ECL) of a newly prepared nanosilver-carbon nanodot (Ag-C-dot) composite and its application for the sensitive detection of sulfide (S(2-)) ions. The Ag-C-dot composite was easily prepared by adding silver nitrate into C-dot colloids through an alkaline reduction. The obtained Ag-C-dots were characterized by UV-vis spectra, fluorescence spectra and transmission electron microscopy. The electrochemical and ECL behaviors of the Ag-C-dot composite were investigated by cyclic voltammetry. Moreover, a simple label-free method to detect S(2-) ions with a high selectivity and sensitivity has been developed based on the ECL of the Ag-C-dot composite in aqueous media. The sensing mechanism could be due to the strong and specific interaction between the S(2-) ions and the Ag atoms/ions on the surface of the Ag-C-dot composite, which dramatically affects the resulting ECL of the Ag-C-dot composite. The linear response to detect S(2-) ions ranges from 0.05 to 100 μM with a detection limit of 0.027 μM (~1 ppb). This work indicates that the Ag-C-dot nanocomposite possesses potential applications for environment sensing.

  13. Compositional Fragmentation Model for the Oxidation of Sulfide Particles in a Flash Reactor

    Science.gov (United States)

    Parra-Sánchez, Víctor Roberto; Pérez-Tello, Manuel; Duarte-Ruiz, Cirilo Andrés; Sohn, Hong Yong

    2014-04-01

    A mathematical model to predict the size distribution and chemical composition of a cloud of sulfide particles during high-temperature oxidation in a flash reactor is presented. The model incorporates the expansion and further fragmentation of the reacting particles along their trajectories throughout the reaction chamber. A relevant feature of the present formulation is its flexibility to treat a variety of flash reacting systems, such as the flash smelting and flash converting processes. This is accomplished by computing the chemical composition of individual particles and the size distribution and overall composition of the particle cloud in separate modules, which are coupled through a database of particle properties previously stored on disk. The flash converting of solid copper mattes is considered as an example. The model predictions showed good agreement with the experimental data collected in a large laboratory reactor in terms of particle size distribution and sulfur remaining in the population of particles. The cumulative contribution and distribution coefficients are introduced to quantify the relationship between specific particle sizes in the feed and those in the reacted products upon oxidation, the latter of which has practical implications on the amount and chemical composition of dust particles produced during the industrial operation.

  14. Upper anterior zone restoration with composites

    OpenAIRE

    Lamas Lara, César; CD, Docente del Área de Operatoria Dental y Endodoncia de la Facultad de Odontología de la UNMSM.; Angulo de la Vega, Giselle; CD, Alumna de la Especialidad de Rehabilitación Oral de la Facultad de Odontología de la UNMSM.

    2014-01-01

    The anterior sector problems are very common in our professional practice and became vital importance to make a suitable rehabilitation in these cases; we can not do a good rehabilitation if we do not know the basic characteristics, both aesthetic and functional. Today the composites are a valid alternative for the restoration of the anterior sector, since they offer to us a conservative and aesthetic possibility, but independently of the material to use we have to based on certain rules or p...

  15. Elemental and isotopic compositions of the hydrothermal sulfide on the East Pacific Rise near 13°N

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The mineralogical,elemental,and isotopic characteristics of a hydrothermal sulfide sample from one dredge station (12°42.30’N,103°54.48’W,water depth 2655 m) on the East Pacific Rise near 13°N were analyzed.The hydrothermal sulfide was composed mainly of sphalerite,chalcopyrite,and pyrite and was a Zn-rich sulfide;in layer ep-s-1,goethite formed by secondary oxidation was found.The concentrations of rare elements,such as Li (0.15×10-6-0.30×10-6),Be (0.01×10-6-0.05×10-6),Zr (73.8×10-9-1344×10-9),Nb (8.14×10-9-64.7×10-9),Hf (2.54×10-9-28.0×10-9),and Ta (0.203×10-9-1.21×10-9),were far lower in the hydrothermal sulfide than in the ocean crust,whereas the content of Au was higher and the contents of Co,Ni,Sr,Cs,Ba,Bi,and U were low.The correlations between Zn and Cr,Cd and Ga,Cu and P,P and In (R2 > 0.8) were positive,whereas those between Zn and Fe,Cu,and Ba (R2 > 0.8) were distinctly negative.From low-temperature mineral assemblages to high-temperature mineral assemblages,the spatial distributions of dispersive and rare elements (e.g.In,Li,Cs) in the hydrothermal sulfide displayed corresponding variations.The variations observed in some elements (e.g.,Cd,Cs,P) are controlled by Zn,Fe,and Cu sulfides,respectively.Seafloor weathering accounts for the enrichment of V,Mn,and rare earth elements (REE) in the henna sulfide-oxidation layer that bears the secondary oxide mineral,leading to identical REE patterns for this layer (ep-s-1) and seawater.Seafloor weathering also distinctly affects the correlations between the element ratios of the hydrothermal sulfide.From high-temperature mineral assemblages to low-temperature mineral assemblages,Fe content and δ 34S value of the hydrothermal sulfide increase gradually,and Zn content and lead isotopic ratios decrease gradually on the contrary,which indicate the influences of seawater on elements and the sulfur and lead isotopic compositions enhance gradually during the formation of hydrothermal sulfides.

  16. Rhenium - osmium heterogeneity of enriched mantle basalts explained by composition and behaviour of mantle-derived sulfides

    Science.gov (United States)

    Harvey, J.; Dale, C. W.; Gannoun, A.; Burton, K. W.

    2010-12-01

    Analyses of enriched mantle (EM) -basalts, using lithophile element-based isotope systems have long provided evidence for discrete, but variable mantle reservoirs [1]. Upon partial melting, the isotopic fingerprint of each reservoir is imparted upon the partial melt produced. However, recent work involving the Re-Os isotope systematics of EM-basalts [2] suggests that it may not be so simple to delimit these previously well defined mantle reservoirs; the “mantle zoo” [3] may contain more reservoirs than previously envisaged. However, a simple model, with varying contributions from two populations of compositionally distinct mantle sulfides can readily account for the observed heterogeneities in Re-Os isotope systematics of such basalts without additional mantle reservoirs. Rhenium-osmium elemental and isotopic analyses of individual sulfide grains separated from spinel lherzolites from Kilbourne Hole, NM, USA demonstrate that two discrete populations of mantle sulfide exist in terms of both Re-Os systematics and textural relationship with co-existing silicates. One population, with a rounded morphology, is preserved in silicate grains and typically possesses high [Os], low [Re] with unradiogenic, typically sub-chondritic, 187Os/188Os attributable to long term isolation in a low-Re environment. By contrast, irregular-shaped sulfides, preserved along silicate grain boundaries, possess low [Os], higher [Re] and a wider range of, but generally supra-chondritic, 187Os/188Os ([Os] typically ≤ 1-2 ppm, 187Os/188Os ≤ 0.3729; this study). This population is thought to represent metasomatic sulfide (e.g. [4,5]). Uncontaminated silicate phases contain negligible Os (mobilized and incorporated into the melt, adding their radiogenic 187Os/188Os signature. Only when sulfides armored within silicates are exposed to the melt through continued partial melting will enclosed sulfides add their high [Os] and unradiogenic 187Os/188Os to the aggregate melt. Platinum-group element

  17. Minerals of Fe in the oxidation zone of massive sulfide ore in the South Pechenga structure zone, Kola region: Identification by the Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Kompanchenko A. A.

    2017-03-01

    Full Text Available The paper presents data on the study of iron-bearing minerals formed in the oxidation zone of massive sulfide ores. The minerals are represented by two groups: oxides, i. e. goethite and lepidocrocite, and sulfates, i. e. melanterite and rozenit. Mineral identification has been produced by Raman spectroscopy, these data have been confirmed by scanning electron microscopy and X-ray powder diffraction. The resulting Raman spectra have been compared with the spectra of the known database and the results of previous studies of these minerals. Goethite and lepidocrocite are polymorphic modifications formed under the specific conditions by the influence of special solutions. Goethite has diagnostic bands at 243 cm–1, 300 cm–1, 391 cm–1, 480 cm–1, 552 cm–1, 681 cm–1 , and 995 cm–1, diagnostic bands of lepidocrocite – 252 cm–1, 381 cm–1, 528 cm–1, and 652 cm–1. Discovered small crystals in the lepidocrocite veins have been diagnosed as magnetite, with diagnostic bands at 678 cm–1, 549 cm–1 , and 316 cm–1. Goethite and lepidocrocite are formed on the surface of a complex pyrrhotite-marcasite aggregate with "bird's-eye" structure. The presence of pyrite and marcasite is confirmed by Raman spectrum which has pyrite bands (343 cm–1 and 403 cm–1 and marcasite bands (323 cm–1 and 386 cm–1. Melanterite and rozenite are formed under the influence of surface water on sulfide ores or other readily degradable iron-bearing minerals, as well as in confined spaces with high humidity. Raman spectra of these minerals well differ from each other allowing them reliably diagnose. There are sulfate anion [SO4]2– vibrations in the range of 990–1010 cm–1, and vibrations of the H–O–H in the range of 3 000–4000 cm–1 and 1 500–1700 cm–1 on the spectra. As a result of the research the authors can certainly confirm that Raman spectroscopy can be used as a reliable method for mineral identification

  18. Platinum-group element concentrations in pyrite from the Main Sulfide Zone of the Great Dyke of Zimbabwe

    Science.gov (United States)

    Piña, R.; Gervilla, F.; Barnes, S.-J.; Oberthür, T.; Lunar, R.

    2016-10-01

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world's second largest resource of platinum-group elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  19. Sodium-ion storage properties of nickel sulfide hollow nanospheres/reduced graphene oxide composite powders prepared by a spray drying process and the nanoscale Kirkendall effect

    Science.gov (United States)

    Park, G. D.; Cho, J. S.; Kang, Y. C.

    2015-10-01

    Spray-drying and the nanoscale Kirkendall diffusion process are used to prepare nickel sulfide hollow nanospheres/reduced graphene oxide (rGO) composite powders with excellent Na-ion storage properties. Metallic Ni nanopowder-decorated rGO powders, formed as intermediate products, are transformed into composite powders of nickel sulfide hollow nanospheres/rGO with mixed crystal structures of Ni3S2 and Ni9S8 phases by the sulfidation process under H2S gas. Nickel sulfide/rGO composite powders with the main crystal structure of Ni3S2 are also prepared as comparison samples by the direct sulfidation of nickel acetate-graphene oxide (GO) composite powders obtained by spray-drying. In electrochemical properties, the discharge capacities at the 150th cycle of the nickel sulfide/rGO composite powders prepared by sulfidation of the Ni/rGO composite and nickel acetate/GO composite powders at a current density of 0.3 A g-1 are 449 and 363 mA h g-1, respectively; their capacity retentions, calculated from the tenth cycle, are 100 and 87%. The nickel sulfide hollow nanospheres/rGO composite powders possess structural stability over repeated Na-ion insertion and extraction processes, and also show excellent rate performance for Na-ion storage.Spray-drying and the nanoscale Kirkendall diffusion process are used to prepare nickel sulfide hollow nanospheres/reduced graphene oxide (rGO) composite powders with excellent Na-ion storage properties. Metallic Ni nanopowder-decorated rGO powders, formed as intermediate products, are transformed into composite powders of nickel sulfide hollow nanospheres/rGO with mixed crystal structures of Ni3S2 and Ni9S8 phases by the sulfidation process under H2S gas. Nickel sulfide/rGO composite powders with the main crystal structure of Ni3S2 are also prepared as comparison samples by the direct sulfidation of nickel acetate-graphene oxide (GO) composite powders obtained by spray-drying. In electrochemical properties, the discharge capacities at the

  20. Remediation of Technetium in Vadose Zone Sediments Using Ammonia and Hydrogen Sulfide Gases

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhong, Lirong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McKinley, James P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qafoku, Nikolla [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lee, Brady D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Saurey, Sabrina D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-04-17

    The feasibility of applying a combination of H2S and NH3 gases for Tc-99 remediation in vadose zone sediments evaluated in laboratory experiments showed a significant mobility decrease from 75 to 95% leachable Tc-99 in untreated sediments to 15 to 48% leachable Tc-99 after gas treatment. Individual H2S or NH3 gas treatment of sediments had little lasting effect. For the combined gas treatment, the H2S gas created reducing conditions at the pore water/mineral interface that pertechnetate was temporarily reduced/precipitated. The NH3 gas created alkaline pore water, which induces some mineral dissolution and subsequent aluminosilicate precipitation as the pH neutralizes, which may coat Tc-99 surface phases and render them less mobile. Surface phase analysis showed Tc-99 associated with weathered basalt clasts and sulfur, possibly from the precipitation of TcSx. Treatment performance was nearly the same at different Tc-99 concentration (34 to 6500 pCi/g), water content (1 to 8%), and gas injection rate, but was sensitive to gas concentrations. Low gas concentrations (< 3%) had insufficient reductant or slower mineral dissolution. High gas concentrations (>30%) formed NH4SH precipitate. The 15 - 23% mobile Tc-99 remaining after gas treatment may be caused by limited time for aluminosilicates to precipitate in experiments. Nitrogen species concentrations showed no nitrate or nitrite production and a significant decrease in the sediment microbial population over three months, suggesting nitrification of added ammonia was inhibited. Overall, this study showed that combined H2S and NH3 gas treatment of low water content sediments was a robust technology to significantly decrease Tc-99 mobility.

  1. POROUS MICROSTRUCTURE OF THE INTERFACIAL TRANSITION ZONE IN GEOPOLYMER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Steinerová M.

    2013-12-01

    Full Text Available The study deals with a comparison of the differences in the structure, composition and micromechanical properties of a metakaolinite geopolymer composite matrix, inside and outside of the interfacial transition zone (ITZ with quartz grains of added silica sand. The microstructure is investigated by a measurement of the mercury porosimetry, microscopy and by a measurement in SEM and AFM, completed by Raman spectroscopy. Weaker mechanical properties, micropores in the ITZ, a higher concentration of Al atoms and hydroxyl groups than in the ambient matrix were detected. The water transport is probably the reason for the micropore formation, caused by disequilibrium in the course of solid-phase building from geopolymer dispersion.

  2. Photocatalytic Oxidation of Diethyl Sulfide Vapor over TiO2-Based Composite Photocatalysts

    Directory of Open Access Journals (Sweden)

    Dmitry Selishchev

    2014-12-01

    Full Text Available Composite TiO2/activated carbon (TiO2/AC and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO reaction of diethyl sulfide (DES vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products – H2O, CO2, CO and SO42− ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples’ stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2 for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2.

  3. Photocatalytic oxidation of diethyl sulfide vapor over TiO2-based composite photocatalysts.

    Science.gov (United States)

    Selishchev, Dmitry; Kozlov, Denis

    2014-12-19

    Composite TiO2/activated carbon (TiO2/AC) and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO) reaction of diethyl sulfide (DES) vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products - H2O, CO2, CO and SO42- ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples' stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF) were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2) for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2.

  4. Influence of diagenesis on the stable isotopic composition of biogenic carbonates from the Gulf of Tehuantepec oxygen minimum zone

    Science.gov (United States)

    Blanchet, C. L.; Kasten, S.; Vidal, L.; Poulton, S. W.; Ganeshram, R.; Thouveny, N.

    2012-04-01

    In order to evaluate the influence of diagenetic and post-sampling processes on the stable oxygen and carbon isotope compositions of biogenic carbonates, we conducted a multiproxy study of organic-rich sediments from the eastern Pacific oxygen minimum zone. Core MD02-2520, which was retrieved from the Gulf of Tehuantepec (Mexico), has seasonal laminations and covers the last 40 kyr. Together with the presence of gypsum crystals and inorganic calcite aggregates, the occurrence of large excursions in the stable oxygen and carbon isotope records of both planktonic and benthic foraminifera (as large as +3‰ in δ18O and -5‰ in δ13C) point to significant secondary transformations. Storage-related gypsum precipitation was ruled out since it implies sulfide reoxidation by oxygen that triggers biogenic calcite dissolution, which proved to be of minor importance here. Instead, precipitation of authigenic calcite during early diagenesis appears to be the most likely process responsible for the observed isotopic excursions. The δ13C composition for inorganic calcite aggregates (-5 to -7‰) suggests a major contribution from anaerobic oxidation of organic matter. The δ34S composition for gypsum crystals (-10 to +15‰) suggests a major contribution from anaerobic reoxidation of authigenic sulfides, potentially involving reactions with metal oxides and sulfur disproportionation. A minor part of the gypsum might possibly have formed as a result of local pore water salinity increases induced by gas hydrate formation.

  5. Hydrogen evolution at nanoporous gold/tungsten sulfide composite film and its optimization

    DEFF Research Database (Denmark)

    Xiao, Xinxin; Engelbrekt, Christian; Li, Zheshen

    2015-01-01

    Development of efficient and economical electrochemical systems for water splitting is a key part of renewable energy technology. Amorphous films of tungsten sulfide have been deposited by electrochemical reduction of tetrathiotungstate ions (WS42-) on dealloyed nanoporous gold (NPG) for electroc......Development of efficient and economical electrochemical systems for water splitting is a key part of renewable energy technology. Amorphous films of tungsten sulfide have been deposited by electrochemical reduction of tetrathiotungstate ions (WS42-) on dealloyed nanoporous gold (NPG...

  6. Interfacial effect on the electrochemical properties of the layered graphene/metal sulfide composites as anode materials for Li-ion batteries

    Science.gov (United States)

    Lv, Yagang; Chen, Biao; Zhao, Naiqin; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

    2016-09-01

    The layered graphene/metal sulfide composites exhibit excellent electrochemical properties as anode materials for lithium ion battery, due to the synergistic effect between metal sulfide and graphene which still needs to be further understood. In this study, Li adsorption and diffusion on MoS2 and SnS2 monolayers and Li2S surface, as well as at their interfaces with graphene, are systematically investigated through first-principles calculations. The analysis of charge density difference, Bader charge, and density of states indicates that the adsorbed Li atoms interact with both the S atoms at metal sulfide surfaces and C atoms in graphene, resulting in larger Li adsorption energies at the interfaces compared with that on the corresponding surfaces, but with almost no enhancement of the energy barriers for Li atom diffusion. The enhanced Li adsorption capability at Li2S/G interface contributes to the extra storage capacity of graphene/metal sulfide composites. Furthermore, the synergistic mechanism between metal sulfide and graphene is revealed. Moreover, band structure analysis shows the electronic conductivity is enhanced with the incorporation of graphene. The results corroborate the interfacial pseudocapacity-like Li atom storage mechanism, and are helpful for the design of layered graphene/metal sulfide composites as anode materials for lithium ion batteries.

  7. Enhanced reactive adsorption of hydrogen sulfide on the composites of graphene/graphite oxide with copper (hydr)oxychlorides.

    Science.gov (United States)

    Mabayoje, Oluwaniyi; Seredych, Mykola; Bandosz, Teresa J

    2012-06-27

    Composites of copper (hydr)oxychlorides with graphite oxide or graphene were synthesized and used as adsorbents of hydrogen sulfide at dynamic conditions at ambient temperatures. The materials were extensively characterized before and after adsorption in order to link their performance to the surface features. X-ray diffraction, FTIR, thermal analysis, TEM, SEM/EDX, and adsorption of nitrogen were used. It was found that the composite with graphene has the most favorable surface features enhancing reactive adsorption of hydrogen sulfide. The presence of moisture in the H2S stream has a positive effect on the removal process owing to the dissociation process. H2S is retained on the surface via a direct replacement of OH groups and via acid-base reactions with the copper (hydr)oxide. Highly dispersed reduced copper species on the surface of the composite with graphene enhance activation of oxygen and cause formation of sulfites and sulfates. Higher conductivity of the graphene phase than that of graphite oxide helps in electron transfer in redox reactions.

  8. Visible-light-enhanced interactions of hydrogen sulfide with composites of zinc (oxy)hydroxide with graphite oxide and graphene.

    Science.gov (United States)

    Seredych, Mykola; Mabayoje, Oluwaniyi; Bandosz, Teresa J

    2012-01-17

    Composites of zinc(oxy)hydroxide-graphite oxide and of zinc(oxy)hydroxide-graphene were used as adsorbents of hydrogen sulfide under ambient conditions. The initial and exhausted samples were characterized by XRD, FTIR, potentiometric titration, EDX, thermal analysis, and nitrogen adsorption. An increase in the amount of H(2)S adsorbed/oxidized on their surfaces in comparison with that of pure Zn(OH)(2) is linked to the structure of the composite, the relative number of terminal hydroxyls, and the kind of graphene-based phase used. Although terminal groups are activated by a photochemical process, the graphite oxide component owing to the chemical bonds with the zinc(oxy)hydroxide phase and conductive properties helps in electron transfer, leading to more efficient oxygen activation via the formation of superoxide ions. Elemental sulfur, zinc sulfide, sulfite, and sulfate are formed on the surface. The formation of sulfur compounds on the surface of zinc(oxy)hydroxide during the course of the breakthrough experiments and thus Zn(OH)(2)-ZnS heterojunctions can also contribute to the increased surface activity of our materials. The results show the superiority of graphite oxide in the formation of composites owing to its active surface chemistry and the possibility of interface bond formation, leading to an increase in the number of electron-transfer reactions.

  9. 30 CFR 250.808 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.808 Section 250.808... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Safety Systems § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of...

  10. Hydrogen Sulfide Mitigates Reperfusion Injury in a Porcine Model of Vascularized Composite Autotransplantation

    Science.gov (United States)

    2014-05-01

    supporting an allograft that can improve quality of life but is not lifesaving. The skin component of a VCA is highly immunogenic and, in combination with...insights into hydrogen sulfide-mediated cytoprotection. Antioxid Redox Signal. 2010;12:1203Y1217. Annals of Plastic Surgery & Volume 72, Number 5, May

  11. Mineralizing conditions and source fluid composition of base metal sulfides in the Lon District, southeastern Iceland

    Science.gov (United States)

    Kremer, C. H.; Thomas, D.; García del Real, P.; Zierenberg, R. A.; Bird, D. K.

    2014-12-01

    Hydrothermal base metal mineralization is rare in Iceland due to the scarcity of evolved magma bodies that discharge metal-rich aqueous fluids into bedrock. One exception is the Lon District of southeastern Iceland, where explosively emplaced rhyolitic breccias host base metal sulfide minerals. We performed petrographic, fluid inclusion, and stable isotope analyses on samples collected in Lon to constrain the conditions of sulfide mineral formation. Based on outcrop and hand sample observations, hot, early-stage hydrothermal fluids precipitated sulfide minerals, quartz, and epidote in rhyolitic breccia and basalt flows. Cooler late-stage fluids precipitated carbonates and quartz in rhyolitic breccia and basalt flows. The order of precipitation of the sulfides was: galena, sphalerite, then chalcopyrite. Homogenization temperatures of liquid-dominated multi-phase fluid inclusions in hydrothermal early-stage quartz coeval with chalcopyrite cluster around 303 °C and 330 °C, indicating precipitation of metallic sulfides in two main hydrothermal fluid pulses early in the period of hydrothermal activity in the Lon District. Freezing point depression analyses of fluid inclusions in quartz show that the sulfide minerals precipitated from a solution that was 4 wt. % NaCl. The 𝛿34S values of sulfides indicate that early-stage hydrothermal sulfur was derived from igneous rocks, either through leaching by non-magmatic hydrothermal fluids or by exsolution of magmatic waters. Early stage epidote 𝛿D values were on average -65.96 per mil, about 14 per mil higher than reported values in epidotes from elsewhere in southeastern Iceland. The 𝛿13C and 𝛿18O values of late-stage carbonates indicate that late stage hydrothermal fluids were meteoric in origin. Collectively, fluid inclusion and stable isotope analyses suggest that early-stage aqueous fluids derived from a mixture of magmatic waters exsolved from the proximal Geitafell intrusion and meteoric

  12. COMPOSITE MATERIALS BASED ON ZINC SULFIDE AND ZINC OXIDE: STRUCTURAL AND BIOCIDAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Sukhodub L.B

    2016-12-01

    Full Text Available Introduction. The widespread use of drugs with antimicrobial action has led to the formation of microorganism resistance against wide range of antibiotics. One of the approaches to dissolving this problem is the substances modification by inorganic bioactive ions in oder to initiate a controlled reaction in the bone tissues and provision of antimicrobial activity. It is known that ZnO-based materials have a pronounced biocompatibility, they are characterized by high limit strength, absolute mechanical hardness, as well as the ability to withstand the harsh operating conditions. The aim of this work is the study of structural and biocidal properties of composite material based on zinc oxide and zinc sulfide (ZnS-ZnO and its complex with an organic substance - sodium alginate (ZnS-ZnO-Alg for use in biomedical purpose. Materials and methods. For the synthesis of ZnS-ZnO composite 50 ml 0.2M solution zinc nitrate was added to the 50 ml 0.2M thiourea CS (NH ₂ ₂ solution and stirred in a shaker for 60 minutes. The formation of the compound took place when added to a mixture of 25 mas.% solution of ammonia with the subsequent heating at 80 oC for 30 minutes. Synthesis of the metalorganic complex of ZnS-ZnO-Alg was performed by above mentioned procedure, but to the thiourea solution was previously added 1 ml of 3 mas.% solution of sodium alginate under ultrasonic mixing.. For the next research composites were dried or lyophilized. Study of antibacterial activity of the ZnS-ZnO and ZnS-ZnO-Alg particles was carried out with the use of nutrient mediums: Muller Hinton, meat-pepton nutrient (MPN. As the reference cultures were used E. coli ATCC 25922, S. aureus ATCC 25923, S. aureus ATSS 29213, S. aureus ATSS-6538, C albicans ATCC 885-653. Determination of the minimum bactericidal concentration (MBC was carried out by a modified serial diluted method in liquid nutrient broth followed plating on solid Muller Hinton nutrient medium. In addition, the

  13. Cobalt (hydr)oxide/graphite oxide composites: importance of surface chemical heterogeneity for reactive adsorption of hydrogen sulfide.

    Science.gov (United States)

    Mabayoje, Oluwaniyi; Seredych, Mykola; Bandosz, Teresa J

    2012-07-15

    Composites of cobalt (hydr)oxide and graphite oxide (GO) were obtained and evaluated as adsorbents of hydrogen sulfide at ambient conditions. The surface properties of the initial and exhausted samples were studied by FTIR, TEM, SEM/EDX, XRD, adsorption of nitrogen, potentiometric titration, and thermal analysis. The results obtained show a significant improvement in their adsorption capacities compared to parent compounds. The importance of the OH groups of cobalt (hydr)oxide/GO composites and new interface chemistry for the adsorption of hydrogen sulfide on these materials is revealed. The oxygen activation by the carbonaceous component resulted in formation of sulfites. Water enhanced the removal process. This is the result of the basic environment promoting dissociation of H(2)S and acid-base reactions. Finally, the differences in the performance of the materials with different mass ratios of GO were linked to the availability of active sites on the surface of the adsorbents, dispersion of these sites, their chemical heterogeneity, and location in the pore system.

  14. Reactivity of sulfide-containing silane toward boehmite and in situ modified rubber/boehmite composites by the silane

    Science.gov (United States)

    Lin, Tengfei; Zhu, Lixin; Chen, Weiwei; Wu, Siwu; Guo, Baochun; Jia, Demin

    2013-09-01

    The silanization reaction between boehmite (BM) nanoplatelets and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) was characterized in detail. Via such modification process, the grafted sulfide moieties on the BM endow reactivity toward rubber and substantially improved hydrophobicity for BM. Accordingly, TESPT was employed as in situ modifier for the nitrile rubber (NBR)/BM compounds to improve the mechanical properties of the reinforced vulcanizates. The effects of BM content and in situ modification on the mechanical properties, curing characteristics and morphology were investigated. BM was found to be effective in improving the mechanical performance of NBR vulcanizates. The NBR/BM composites could be further strengthened by the incorporation of TESPT. The interfacial adhesion of NBR/BM composites was obviously improved by the addition of TESPT. The substantially improved mechanical performance was correlated to the interfacial reaction and the improved dispersion of BM in rubber matrix.

  15. Structural, chemical and optical properties of the polyethylene–copper sulfide composite thin films synthesized using polythionic acid as sulfur source

    Energy Technology Data Exchange (ETDEWEB)

    Ancutiene, Ingrida [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu st. 19, LT-50254 Kaunas (Lithuania); Navea, Juan G. [Chemistry Department, Skidmore College, 815N. Broadway, Saratoga Springs, NY 12866 (United States); Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2015-08-30

    Graphical abstract: Several crystalline copper sulfide phases (spionkopite, anilite, digenite, djurleite, chalcocite) were obtained in as synthesized samples (PE-Cu{sub x}S) and elucidated using XRD. Thickness of the films obtained ranged from several microns to ∼18 μm and depended on the Cu(II/I) exposure time. Bandgap of the materials obtained was measured and ranged from 1.88 to 1.17 eV. Importantly, heating samples, many copper sulfide crystalline phase containing films at 100 °C in inert atmosphere invariably resulted in a single copper sulfide, anilite (Cu{sub 1.75}S), phase. - Highlights: • We investigated deposition of a single phase copper sulfide on polyethylene. • A single sulfur precursor – H{sub 2}S{sub 33}O{sub 6} – was used. • Increasing exposure time to Cu(II/I) yielded Cu{sub x}S with higher x values. • Heating at 100 °C in N{sub 2} resulted in a single anilite (Cu{sub 1.75}S) phase. • Cu(I) and Cu(II) compounds were detected using XPS. - Abstract: Synthesis and properties of thin copper sulfide films deposited on polyethylene were explored for the development of low cost hybrid organic–inorganic photovoltaic materials. Polyethylene was used as a model organic host material for thin copper sulfide film formation. Adsorption–diffusion method was used which utilized consecutive exposure of polyethylene to polythionic acid followed by aqueous Cu(II/I) solution. Several crystalline copper sulfide phases were obtained in synthesized samples and elucidated using X-ray diffraction. Surface chemical composition determined using X-ray photoelectron spectroscopy showed the presence of copper sulfides in combination with copper hydroxide. Thickness of the composite material films ranged from several microns to ∼18 μm and depended on the Cu(II/I) exposure time. Bandgap of the materials obtained was measured and ranged from 1.88 to 1.17 eV. Importantly, heating these complex copper sulfide crystalline phase containing films at 100

  16. Hollow-spherical composites of Polyaniline/Cobalt Sulfide/Carbon nanodots with enhanced magnetocapacitance and electromagnetic wave absorption capabilities

    Science.gov (United States)

    Ge, Chuanjun; Zhang, Xiang; Liu, Jian; Jin, Feng; Liu, Jichang; Bi, Hong

    2016-08-01

    Hollow-spherical composites of polyaniline/cobalt sulfide/carbon nanodots (PANI/CoS/CDs-0.5T) have been synthesized by in situ polymerization under an applied magnetic field (MF) of 0.5 T. As a control, PANI/CoS/CDs-0T composites have been synthesized without a MF. Both composites acting as electrodes present obvious magnetocapacitances at a scan rate of 100 mV s-1 while the electrochemical cell tested under an external MF of 0.5 T. Notably, PANI/CoS/CDs-0.5T composites show larger magnetocapacitances than PANI/CoS/CDs-0T composites at different scan rates from 5 to 100 mV s-1. Electrochemical impedance spectroscopy (EIS) results indicate that MF can reduce charge transfer resistance at electrode/electrolyte interface. More importantly, PANI/CoS/CDs-0.5T composites show a much stronger electromagnetic wave (EMW) absorbing capability than PANI/CoS/CDs-0T in the range of 2-18 GHz which is attributed to an increased dielectric loss and a magnetic loss in low frequency range of 2-12.5 GHz. MF-induced ferromagnetic nanodomains of Co2+ clusters in the PANI/CoS/CDs-0.5T composites increase the complex permittivity and create more interfacial polarizations or the Maxwell-Wagner effect, which leads to increased dielectric loss. Compared with PANI/CoS/CDs-0T composites with diamagnetic behaviour, MF-induced weak ferromagnetism of CoS in the PANI/CoS/CDs-0.5T composites has caused additional magnetic loss. This work provides an efficient way for modulating electrochemical or electromagnetic properties of inorganic/polymer nanocomposites by employing an external MF.

  17. Effects of Feed Composition and Feed Impurities in the Catalytic Conversion of Syngas to Higher Alcohols over Alkali-Promoted Cobalt–Molybdenum Sulfide

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt; Jensen, Peter Arendt; Jensen, Anker Degn

    2011-01-01

    Alkali-promoted cobalt–molybdenum sulfide is a potential catalyst for the conversion of syngas into higher alcohols. This work is an investigation of how the feed composition influences the behavior of the sulfide catalyst. In a sulfur-free syngas the production of higher alcohols is observed...... to be optimal with an equimolar mixture of CO and H2 in the feed, while the methanol production benefits from an increasing hydrogen content in the feed. The influence of NH3 and H2O in the syngas feed has also been investigated. Ammonia (741 ppmv) in the feed is observed to cause a general and largely...

  18. Novel Composite Hydrogen-Permeable Membranes for Nonthermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Morris Argyle; John Ackerman; Suresh Muknahallipatna; Jerry Hamann; Stanislaw Legowski; Gui-Bing Zhao; Sanil John; Ji-Jun Zhang; Linna Wang

    2007-09-30

    The goal of this experimental project was to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a nonthermal plasma and to recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), but it was not achieved at the moderate pressure conditions used in this study. However, H{sub 2}S was successfully decomposed at energy efficiencies higher than any other reports for the high H{sub 2}S concentration and moderate pressures (corresponding to high reactor throughputs) used in this study.

  19. Nanostructured Multilayer Composite Films of Manganese Dioxide/Nickel/Copper Sulfide Deposited on Polyethylene Terephthalate Supporting Substrate

    Directory of Open Access Journals (Sweden)

    Awangku Nabil Syafiq Bin Awangku Metosen

    2015-01-01

    Full Text Available Nanostructured multilayer manganese dioxide/nickel/copper sulfide (MnO2/Ni/CuS composite films were successfully deposited onto supporting polyethylene terephthalate (PET substrate through the sequential deposition of CuS, Ni, and MnO2 thin films by chemical bath deposition, electrodeposition, and horizontal submersion deposition techniques, respectively. Deposition of each thin-film layer was optimized by varying deposition parameters and conditions associated with specific deposition technique. Both CuS and Ni thin films were optimized for their electrical conductivity whereas MnO2 thin film was optimized for its microstructure and charge capacity. The electrochemical properties of nanostructured multilayer MnO2/Ni/CuS composite films were evaluated by cyclic voltammetry as electrode materials of an electrochemical capacitor prototype in a dual-planar device configuration. Cyclic voltammogram in mild Na2SO4 aqueous electrolyte exhibited a featureless and almost rectangular shape which was indicative of the ideal capacitive behavior and high cycling reversibility of the electrochemical capacitor prototype. Nanostructured multilayer MnO2/Ni/CuS composite films on supporting polyethylene terephthalate (PET substrate could potentially be utilized as electrode materials for the fabrication of high performance electrochemical capacitors.

  20. 30 CFR 250.604 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.604 Section 250.604... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Workover Operations § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  1. 30 CFR 250.504 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.504 Section 250.504... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Completion Operations § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  2. Direct electrochemistry and electrocatalysis of horseradish peroxidase with hyaluronic acid-ionic liquid-cadmium sulfide nanorod composite material

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhihong [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Li Xia; Wang Yan [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Zeng Yan [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Sun Wei, E-mail: sunwei@qust.edu.cn [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Huang Xintang [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China)

    2010-06-18

    A new composite material consisted of hyaluronic acid (HA), ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF{sub 4}) and cadmium sulfide (CdS) nanorod was fabricated and used for the immobilization of horseradish peroxidase (HRP) on the surface of a carbon ionic liquid electrode (CILE), which was prepared with 1-ethyl-3-methyl-imidazolium ethylsulphate ([EMIM]EtOSO{sub 3}) as modifier. Spectroscopic results indicated that HRP remained its native structure in the composite film. Based on the synergistic effect of the materials used, an obvious promotion to the direct electron transfer efficient between HRP and CILE was achieved with a pair of well-defined redox peaks appeared in 0.1 mol L{sup -1} phosphate buffer solution, indicating the realization of the direct electrochemistry of HRP. The immobilized HRP showed good electrocatalytic activity towards the reduction of trichloroacetic acid and H{sub 2}O{sub 2} with the electrochemical parameters calculated. Based on the fabricated electrode, a new third-generation electrochemical biosensor was constructed with good stability and reproducibility.

  3. Composite Zones Produced In Situ in the Ni3Al Phase

    Directory of Open Access Journals (Sweden)

    E. Olejnik

    2013-01-01

    Full Text Available The study presents the results of research on the development of composite zones in castings based on the intermetallic phase of Ni3Al.Composite zones were obtained by placing packets with substrates for the reaction of titanium carbide in a foundry mould. To provide avariable carbides content in the composite zone, two compositions of the packets were prepared. The first packet contained only substratesfor the reaction of TiC synthesis; the second one also contained a filler. The resulting composite zones in castings were examined for the filler effect on changes in the volume fraction, size and morphology of carbides in the zone. In addition, the effect of filler on the mechanical properties of the zone was verified, observing changes of Vickers hardness in this area. It was found that the presence of filler in the composition of the packet for synthesis reduced the content of carbides, as well as their size and morphology. Lower surface content of carbides reduced hardness of the zone, which enabled smooth control of the mechanical properties. At the same time, the use of the selected filler did not disturb the course of the TiC carbide synthesis.

  4. The iron isotope composition of enstatite meteorites: Implications for their origin and the metal/sulfide Fe isotopic fractionation factor

    Science.gov (United States)

    Wang, Kun; Savage, Paul S.; Moynier, Frédéric

    2014-10-01

    Despite their unusual chemical composition, it is often proposed that the enstatite chondrites represent a significant component of Earth’s building materials, based on their terrestrial similarity for numerous isotope systems. In order to investigate a possible genetic relationship between the Fe isotope composition of enstatite chondrites and the Earth, we have analyzed 22 samples from different subgroups of the enstatite meteorites, including EH and EL chondrites, aubrites (main group and Shallowater) and the Happy Canyon impact melt. We have also analyzed the Fe isotopic compositions of separated (magnetic and non-magnetic) phases from both enstatite chondrites and achondrites. On average, EH3-5 chondrites (δ56Fe = 0.003 ± 0.042‰; 2 standard deviation; n = 9; including previous literature data) as well as EL3 chondrites (δ56Fe = 0.030 ± 0.038‰; 2 SD; n = 2) have identical and homogeneous Fe isotopic compositions, indistinguishable from those of the carbonaceous chondrites and average terrestrial peridotite. In contrast, EL6 chondrites display a larger range of isotopic compositions (-0.180‰ < δ56Fe < 0.181‰; n = 11), a result of mixing between isotopically distinct mineral phases (metal, sulfide and silicate). The large Fe isotopic heterogeneity of EL6 is best explained by chemical/mineralogical fragmentation and brecciation during the complex impact history of the EL parent body. Enstatite achondrites (aubrites) also exhibit a relatively large range of Fe isotope compositions: all main group aubrites are enriched in the light Fe isotopes (δ56Fe = -0.170 ± 0.189‰; 2 SD; n = 6), while Shallowater is, isotopically, relatively heavy (δ56Fe = 0.045 ± 0.101‰; 2 SD; n = 4; number of chips). We take this variation to suggest that the main group aubrite parent body formed a discreet heavy Fe isotope-enriched core, whilst the Shallowater meteorite is most likely from a different parent body where core and silicate material remixed. This could be

  5. The Structure and Physical Properties of Composites Formed from Molybdenum Sulfide

    Directory of Open Access Journals (Sweden)

    L.S. Yablon

    2016-06-01

    Full Text Available It was found that the composite MoS2/C with increasing carbon content increases parameter of lattice с. In this composite Raman spectra revealed two intense phonon bands first order G and D at ~ 1591 cm – 1 and 1354 cm – 1, respectively, which are caused by inelastic scattering of light by fluctuations sp2-bound carbon atoms. Established that the molybdenum sulphide at a temperature of 650 °C is observed exothermic effect caused by desorption of oxygen and water. It is shown that the mechanical mixing nanoporous carbon disulfide molybdenum leads to a sharp increase in conductivity resulting composite.

  6. Cobalt Sulfide/Graphene Composite Hydrogel as Electrode for High-Performance Pseudocapacitors

    Science.gov (United States)

    Meng, Xiaoqian; Deng, Jin; Zhu, Junwu; Bi, Huiping; Kan, Erjun; Wang, Xin

    2016-02-01

    Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g-1 at a current density of 1 A g-1 (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications.

  7. Petrology, geochemistry and U-Pb geochronology of magmatic rocks from the high-sulfidation epithermal Au-Cu Chelopech deposit, Srednogorie zone, Bulgaria

    Science.gov (United States)

    Chambefort, Isabelle; Moritz, Robert; von Quadt, Albrecht

    2007-10-01

    The Chelopech deposit is one of the largest European gold deposits and is located 60 km east of Sofia, within the northern part of the Panagyurishte mineral district. It lies within the Banat-Srednegorie metallogenic belt, which extends from Romania through Serbia to Bulgaria. The magmatic rocks define a typical calc-alkaline suite. The magmatic rocks surrounding the Chelopech deposit have been affected by propylitic, quartz-sericite, and advanced argillic alteration, but the igneous textures have been preserved. Alteration processes have resulted in leaching of Na2O, CaO, P2O5, and Sr and enrichment in K2O and Rb. Trace element variation diagrams are typical of subduction-related volcanism, with negative anomalies in high field strength elements (HFSE) and light element, lithophile elements. HFSE and rare earth elements were relatively immobile during the hydrothermal alteration related to ore formation. Based on immobile element classification diagrams, the magmatic rocks are andesitic to dacitic in compositions. Single zircon grains, from three different magmatic rocks spanning the time of the Chelopech magmatism, were dated by high-precision U-Pb geochronology. Zircons of an altered andesitic body, which has been thrust over the deposit, yield a concordant 206Pb/238U age of 92.21 ± 0.21 Ma. This age is interpreted as the crystallization age and the maximum age for magmatism at Chelopech. Zircon analyses of a dacitic dome-like body, which crops out to the north of the Chelopech deposit, give a mean 206Pb/238U age of 91.95 ± 0.28 Ma. Zircons of the andesitic hypabyssal body hosting the high-sulfidation mineralization and overprinted by hydrothermal alteration give a concordant 206Pb/238U age of 91.45 ± 0.15 Ma. This age is interpreted as the intrusion age of the andesite and as the maximum age of the Chelopech epithermal high-sulfidation deposit. 176Hf/177Hf isotope ratios of zircons from the Chelopech magmatic rocks, together with published data on the

  8. Deciphering a multistage history affecting U-Cu(-Fe) mineralization in the Singhbhum Shear Zone, eastern India, using pyrite textures and compositions in the Turamdih U-Cu(-Fe) deposit

    Science.gov (United States)

    Pal, Dipak C.; Barton, Mark D.; Sarangi, A. K.

    2009-01-01

    The ˜200-km-long intensely deformed Singhbhum Shear Zone (SSZ) in eastern India hosts India’s largest U and Cu deposits and related Fe mineralization. The SSZ separates an Archaean cratonic nucleus to the south from a Mesoproterozoic fold belt in the North and has a complex geologic history that obscures the origin of the contained iron-oxide-rich mineral deposits. This study investigates aspects of the history of mineralization in the SSZ by utilizing new petrographic and electron microprobe observations of pyrite textures and zoning in the Turamdih U-Cu(-Fe) deposit. Mineralization at Turamdih is hosted in intensively deformed quartz-chlorite schist. Sulfides and oxides include, in inferred order of development: (a) magmatic Fe(-Ti-Cr) oxide and Fe-Cu(-Ni) sulfide minerals inferred to be magmatic (?) in origin; followed by (b) uranium, Fe-oxide, and Fe-Cu(-Co) sulfide minerals that predate most or all ductile deformation, and are inferred to be of hydrothermal origin; and (c) Fe-Cu sulfides that were generated during and postdating ductile deformation. These features are associated with the formation of three compositionally and texturally distinct pyrites. Pyrite (type-A), typically in globular-semiglobular composite inclusions of pyrite plus chalcopyrite in magnetite, is characterized by very high Ni content (up to 30,700 ppm) and low Co to Ni ratios (0.01-0.61). The textural and compositional characteristics of associated chalcopyrite and rare pyrrhotite suggest that this pyrite could be linked to the magmatic event via selective replacement of magmatic pyrrhotite. Alternatively, this pyrite and associated sulfide inclusions might be cogenetic with hydrothermal Fe-oxide. Type-B pyrite that forms elongate grains and irregular relics and cores of pyrite with high Co contents (up to 23,630 ppm) and high Co to Ni ratios (7.2-140.9) are interpreted to be related to hydrothermal mineralization predating ductile deformation. A third generation of pyrite (type C

  9. High temperature hydrogen sulfide adsorption on activated carbon - I. Effects of gas composition and metal addition

    Science.gov (United States)

    Cal, M.P.; Strickler, B.W.; Lizzio, A.A.

    2000-01-01

    Various types of activated carbon sorbents were evaluated for their ability to remove H2S from a simulated coal gas stream at a temperature of 550 ??C. The ability of activated carbon to remove H2S at elevated temperature was examined as a function of carbon surface chemistry (oxidation, thermal desorption, and metal addition), and gas composition. A sorbent prepared by steam activation, HNO3 oxidation and impregnated with Zn, and tested in a gas stream containing 0.5% H2S, 50% CO2 and 49.5% N2, had the greatest H2S adsorption capacity. Addition of H2, CO, and H2O to the inlet gas stream reduced H2S breakthrough time and H2S adsorption capacity. A Zn impregnated activated carbon, when tested using a simulated coal gas containing 0.5% H2S, 49.5% N2, 13% H2, 8.5% H2O, 21% CO, and 7.5% CO2, had a breakthrough time of 75 min, which was less than 25 percent of the length of breakthrough for screening experiments performed with a simplified gas mixture of 0.5% H2S, 50% CO2, and 49.5% N2.

  10. Layered nickel sulfide-reduced graphene oxide composites synthesized via microwave-assisted method as high performance anode materials of sodium-ion batteries

    Science.gov (United States)

    Qin, Wei; Chen, Taiqiang; Lu, Ting; Chua, Daniel H. C.; Pan, Likun

    2016-01-01

    Layered nickel sulfide (NS)-reduced graphene oxide (RGO) composites are prepared via a simple microwave-assisted method and subsequent annealing in N2/H2 atmosphere. A detailed array of characterization tools are used to study their morphology, structure and electrochemical performance. It was found that these composites exhibit significantly improved sodium-ion storage ability as compared with pure NS under galvanostatic cycling at a specific current of 100 mA g-1 in a potential limitation of 0.005-3.0 V. Furthermore, the composite with the RGO content of 35 wt.% achieves a high maximum reversible specific capacity of about 391.6 mAh g-1 at a specific current of 100 mA g-1 after 50 cycles. These results prove that NS-RGO composites are highly promising when applied directly as anode materials in sodium-ion batteries.

  11. Pinot noir wine volatile and anthocyanin composition under different levels of vine fruit zone leaf removal.

    Science.gov (United States)

    Feng, Hui; Skinkis, Patricia A; Qian, Michael C

    2017-01-01

    The impacts of fruit zone leaf removal on volatile and anthocyanin compositions of Pinot noir wine were investigated over two growing seasons. Wine volatiles were analyzed by multiple techniques, including headspace solid phase microextraction-GC-MS (HS-SPME-GC-MS), headspace-GC-FID (HS-GC-FID) and stir bar sorptive extraction-GC-MS (SBSE-GC-MS). Fruit zone leaf removal affected the concentration of many grape-derived volatile compounds such as terpene alcohols and C13-norisoprenoids in wine, although the degree of impact depended on the vintage year and severity of leaf removal. Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol and β-damascenone but had no impact on other terpene alcohols or β-ionone. Fruit zone leaf removal had no consistent impact on C6 alcohols, volatile phenols, lactones, fermentation-derived alcohols, acids, or most esters. Fruit zone leaf removal increased anthocyanins in final wine.

  12. The composition, structure, and stability of guinier-preston zones in lunar and terrestrial orthopyroxene

    Science.gov (United States)

    Nord, G.L.

    1980-01-01

    Lunar and terrestrial orthopyroxenes (Mg,Fe,Ca)2Si2O6 contain varying abundances of coherent, Ca-enriched Guinier-Preston (G.P.) zones. G.P. zones 5-6 unit cells thick have been found in one lunar sample whereas all other examples (lunar and terrestrial) are only one unit-cell-thick. Electron diffraction maxima from the larger lunar G.P. zones indicate that d100=18.52 A?? whereas, d100=18.2 A?? for the host. This increase in the a direction corresponds to an increase in calcium content in the G.P. zones over that of the host of ???25 mol% Ca2Si2O6. Diffraction patterns of the hk0 net from an area containing G.P. zones show extra spots (h=2 n+1) not observed in the host orthopyroxene (Pbca), that violate the a-glide of the host. The G.P. zones, therefore, have space group Pbc21 if it is assumed that the c-glide of pyroxene is retained and the space group of the G.P. zone is a subgroup of Pbca. The loss of the a-glide in the G.P. zones results in 4 distinct silica chains and 4 distinct cation sites M1A, M1B, M2A, M2B; by symmetry, equivalent M2A or M2B sites are clustered together in only one-half of the unit cell. As one-fourth of the divalent cations in the G.P. zones are calcium, ordering of Ca on M2A or M2B would produce a zone 9 A?? thick extended parallel to (100) with the composition of Ca(Mg,Fe)Si2O6, but constrained by the host to the structure of orthopyroxene. This zone and the Ca-poor half-unit-cell then constitute an 18 A?? thick G.P. zone. Heating experiments of varying duration indicate that the zones become unstable with respect to the host orthopyroxene at ???950??C for Wo0.6 and ???1,050??C for Wo2.5. The zones are interpreted in terms of the pyroxene subsolidus as a metastable phase having either a solvus relationship with orthopyroxene or originating as a distinct phase. The size, distribution, composition and structure of G.P. zones may be an important indicator of the low-temperature thermal history of orthopyroxene. ?? 1980 Springer-Verlag.

  13. He, Ne and Ar isotope compositions of fluid inclusions in hy-drothermal sulfides from the TAG hydrothermal field, Mid-Atlantic Ridge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Helium, neon and argon isotope compositions of fluid inclusionshave been measured in hydrothermal sulfide samples from the TAG hydrothermal field at the Mid-Atlantic Ridge. Fluid-inclusion 3He/4He ratios are 2.2-13.3 times the air value (Ra), and with a mean of 7.2 Ra. Com-parison with the local vent fluids (3He/4He=7.5-8.2 Ra) and mid-ocean ridge basalt values (3He/4He=6-11 Ra) shows that the variation range of 3He/4He ratios from sulfide-hosted fluid inclu-sions is significantly large. Values for 20Ne/22Ne are from 10.2 to 11.4, which are significantly higher than the atmospheric ratio (9.8). And fluid-inclusion 40Ar/36Ar ratios range from 287 to 359, which are close to the atmospheric values (295.5). These results indicate that the noble gases of fluid inclu-sions in hydrothermal sulfides are a mixture of mantle- and seawater-derived noble gases; the partial mantle-derived components of trapped hydrothermal fluids may be from the lower mantle; the helium of fluid inclusions is mainly from upper mantle; and the Ne and Ar components are mainly from seawater.

  14. Sulfur isotope composition of metasomatised mantle xenoliths from the Bultfontein kimberlite (Kimberley, South Africa): Contribution from subducted sediments and the effect of sulfide alteration on S isotope systematics

    Science.gov (United States)

    Giuliani, Andrea; Fiorentini, Marco L.; Martin, Laure A. J.; Farquhar, James; Phillips, David; Griffin, William L.; LaFlamme, Crystal

    2016-07-01

    Sulfur isotopes are a powerful geochemical tracer in high-temperature processes, but have rarely been applied to the study of mantle metasomatism. In addition, there are very limited S isotope data on sub-continental lithospheric mantle (SCLM) material. For cratonic regions, these data are restricted to sulfide inclusions in diamonds. To provide new constraints on the S isotope composition of the SCLM and on the source(s) of mantle metasomatic fluids beneath the diamondiferous Kimberley region (South Africa), we investigated the S isotope systematics of five metasomatised mantle xenoliths from the Bultfontein kimberlite. Pentlandite and chalcopyrite in these xenoliths were analysed by in situ secondary-ion mass spectrometry (SIMS), with bulk-rock material measured by gas source isotope ratio mass spectrometry techniques. Based on previous studies, the xenoliths experienced different types of metasomatism to one another at distinct times (∼180 and ∼90-80 Ma). Contained pentlandite grains show variable alteration to heazlewoodite (i.e. Ni sulfide) + magnetite. The in situ S isotope analyses of pentlandite exhibit a relatively restricted range between -5.9 and - 1.4 ‰δ34 S (compared to VCDT), with no statistically meaningful differences between samples. Chalcopyrite only occurs in one sample and shows δ34 S values between -5.4 and - 1.0 ‰. The bulk-rock Ssulfide isotope analyses vary between -3.4 and + 0.8 ‰δ34 S. Importantly, the only sample hosting dominantly fresh sulfides shows a bulk-rock δ34 S value consistent with the mean value for the sulfides, whereas the other samples exhibit higher bulk 34S/32S ratios. The differences between bulk-rock and average in situδ34 S values are directly correlated with the degree of sulfide alteration. This evidence indicates that the elevated 34S/32S ratios in the bulk samples are not due to the introduction of heavy S (commonly as sulfates) and are best explained by isotopic fractionation coupled with the removal

  15. Modelling of composite concrete block pavement systems applying a cohesive zone model

    DEFF Research Database (Denmark)

    Skar, Asmus; Poulsen, Peter Noe

    This paper presents a numerical analysis of the fracture behaviour of the cement bound base material in composite concrete block pavement systems, using a cohesive zone model. The functionality of the proposed model is tested on experimental and numerical investigations of beam bending tests...

  16. Effect of lighting conditions of coastal zone of Knyaginya lake on composition of macrophyte biohydrocenoses

    Directory of Open Access Journals (Sweden)

    B. O. Baranovsky

    2005-10-01

    Full Text Available In articlе the stuffs of researches of influence of a mode of illuminating intensity of coastal zone of a different exposition flood-land of lake Knyaginya (valley Samara on composition of highest aqueous green and macrozoobentos macrophytes biogeocenose are submitted.

  17. Diffuse-flow hydrothermal field in an oceanic fracture zone setting, Northeast Pacific: Deposit composition

    Science.gov (United States)

    Hein, J.R.; Koski, R.A.; Embley, R.W.; Reid, J.; Chang, S.-W.

    1999-01-01

    This is the first reported occurrence of an active hydrothermal field in an oceanic fracture zone setting. The hydrothermal field occurs in a pull-apart basin within the Blanco Fracture Zone (BFZ), which has four distinct mineral deposit types: (1) barite mounds and chimneys, (2) barite stockwork breccia, (3) silica-barite beds, and (4) silica, barite, and Fe-Mn oxyhydroxide in sediments. All deposit types contain minor amounts of sulfides. In barite stockwork, silica-barite beds, and mineralized sediment, Ba, Ph, Ag, S, Au, Zn, Cu, Hg, TI, As, Mo, Sb, U, Cd, and Cu are enriched relative to unmineralized rocks and sediments of the BFZ. Fe and Mn are not enriched in the barite stockwork or silica-barite beds, but along with P, Co, and Mg are enriched in the mineralized sediments. Silver contents in deposits of the hydrothermal field range up to 86 ppm, gold to 0.7 ppm, zinc to 3.2%, copper to 0.8%, and barium to 22%. Mineralization occurred by diffuse, low to intermediate temperature (mostly Metallurgy and Petroleum. All rights reserved.

  18. The δ 34S composition of sulfates and sulfides at the Los Humeros geothermal system, Mexico and their application to physicochemical fluid evolution

    Science.gov (United States)

    Martinez Serrano, Raymundo G.; Jacquier, Bertrand; Arnold, Michel

    1996-09-01

    The δ 34S isotopic composition of sulfur was determined in more than 105 pyrite samples found in volcanic formations as well as in the sulfates and sulfides dissolved in the present-day geothermal fluids in the Los Humeros system, Mexico. Analysis of the isotopic values demonstrated that the sulfur compounds of the geothermal system were derived from a magmatic source (δ 34S ΣS — 1%.). The calculation of the different pH-FO 2-(FS 2) diagrams showed that the sulfates and sulfides dissolved in the present-day fluids from well H1 do not show chemical equilibrium conditions as was indicated previuosly by Arnold and Gonzalez-P. (1987). The reason for this is that the physicochemical characteristics of the system have been evolving almost continuously as a result of the exploration and exploitation of the thermal fluids from the system. The residence time of the fluids in the geothermal reservoir is now reduced and the chemical and isotopic reactions that occur between fluids and minerals are not carried out completely. Due to the thermodynamic evolution of the fluids, equilibrium among the sulfur phases dissolved in the fluids could not be demonstrated. The δ 34S values of pyrite sampled at different depths in the geothermal system display evidence for different isotopic fractionation produced by boiling, fluid mixing, and vapor condensation in meteoric waters. The δ 34S values of sulfates in the present-day fluids suggest that these were derived from the oxidation of H 2S at relatively shallow depths (< 600 m). In fact, the isotopic compositions of these sulfates trend towards δ 34S values of sulfides found in the steam phase.

  19. Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone

    Science.gov (United States)

    Mal'tseva, L. A.; Tyushlyaeva, D. S.; Mal'tseva, T. V.; Pastukhov, M. V.; Lozhkin, N. N.; Inyakin, D. V.; Marshuk, L. A.

    2014-10-01

    The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1-1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

  20. Helium,neon and argon isotope compositions of fluid inclu-sions in massive sulfides from the Jade hydrothermal field,the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhigang; QIN Yunshan; ZHAI Shikui

    2004-01-01

    Helium, neon and argon isotope compositions of fluid inclusions have been measured in massive sulfide samples from the Jade hydrothermal field in the central Okinawa Trough. Huid-inclusion 3He/4He ratios are between 6.2 and 10.1 times the air value (Ra), and with a mean of 7.8Ra, which are consistent with the mid-ocean ridge basalt values [3He/4He≈(6Ra~11Ra)]. Values for 20Ne/22Ne are from 10.7 to 11.3, which are significantly higher than the atmospheric ratio (9.8).And the fluid-inclusion 40Ar/36Ar ratios range from 287 to 334, which are close to the atmosperic values (295.5). These results indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle- and seawater-derived components, and the helium of fluid inclusions is mainly from mantle, the nelium and argon isotope compositions are mainly from seawater.

  1. A REVIEW OF THE MEASUREMENT AND DEVELOPMENT OF CRYSTALLINITY AND ITS RELATION TO PROPERTIES IN NEAT POLY(PHENYLENE SULFIDE) AND ITS FIBER REINFORCED COMPOSITES

    Energy Technology Data Exchange (ETDEWEB)

    Spruiell, J.E.

    2005-01-31

    This literature review paper was prepared for the Department of Energy Automotive Lightweighting Program to address materials interest expressed by the Automotive Composites Consortium and it summarizes the measurement and development of crystallinity and its relation to properties in poly(phenylene sulfide) (PPS) and its fiber reinforced composites. The objective of this effort was to broaden the understanding of low-cost, semi-crystalline thermoplastic resins and composites for use in potential future automotive applications. PPS has an excellent combination of attributes including good mechanical properties and thermal stability, high chemical resistance, low moisture absorption, good weathering resistance, high dimensional stability, low flammability, and excellent processability. Specific areas addressed in this report include: Structure of PPS; Techniques for measuring crystallinity; Crystallinity as a function of prior treatment; Crystallization kinetics and morphology; Effect of variation of crystallinity on properties of PPS and its composites; Environmental stability; Unusual effects of cooling rates and degree of crystallinity on mechanical properties of AS4/PPS composites; Recent PPS laminate data (Ten Cate Advanced Composites); and Recommendations for future research.

  2. Composition Dependent Evolution in Mass Flux from Binary Trichloroethene/Tetrachloroethene-DNAPL Source Zones

    Science.gov (United States)

    Walker, D. I.; Cápiro, N. L.; Granbery, E. K.; Pennell, K. D.

    2010-12-01

    In order to accurately predict the efficacy of subsurface remediation for sites contaminated with multicomponent dense non-aqueous phase liquids (DNAPLs), it is necessary to link changes in aqueous phase contaminant discharge with source composition and distribution. Dissolution from a binary 1:1 (molar) mixture of trichloroethene- (TCE) and tetrachloroethene- (PCE) DNAPL was measured in three separate 2-dimensional aquifer cells (100 x 48 x 1.4 cm) that were packed with different background media (1:1 mixture 20:30 and 40:50 mesh; 20:30 mesh and 40:50 mesh Accusand) and low permeability zones. Initial DNAPL source zone architectures were varied to yield ganglia to pool (GTP) ratios of 0.44, 1.56, and 1.72. Down-gradient plume evolution and DNAPL spatial distribution were measured every 5 pore volumes (PV) from side port samples and a light transmission system that allowed non-invasive measurement of volumetric DNAPL saturation and source descriptive metrics at a resolution of 0.03 to 0.08 mm2. Flux-averaged PCE and TCE effluent concentrations were measured every 0.7 PVs from a fully screened effluent chamber. To accelerate changes in source zone architecture and overall mass removal, two surfactant floods (4% w/w Tween 80) were completed after mass discharge from the source zone reached a steady state. Mass flux reductions for a given amount of DNAPL mass removed were found to correspond strongly to the molar composition of DNAPL in the source zone and the initial DNAPL saturation distribution metric (e.g., GTP). Percent reductions in mass flux from the aquifer cells with ganglia dominated architectures were 98 and 72% for TCE and PCE respectively, with a final overall NAPL source zone molar ratio of 0.49:0.51 TCE: PCE ; and 97 and 79% for TCE and PCE with molar ratios of 0.19:0.81 TCE:PCE. Reductions in mass flux from the pool dominated source zone were 90 and 53% for TCE and PCE with a final overall DNAPL source zone mole fraction of 0.26:0.74 TCE:PCE. These

  3. Sulfide mineralization in ultramafic rocks of the Faryab ophiolite complex, southern Kerman

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Rajabzadeh

    2015-10-01

    melting of the upper mantle. Sulfide mineralization in the complex is confined to cumulate rocks in northern part of ophiolite column. The mineralization is olivine-rich clinopyroxene and wehrlite. Petrographic investigation of sulfides in host ultramafics indicated two sulfide generations. In the first generation, primary magmatic sulfides occurred as interstitial disseminations, generally as anhedral grains. In the second generation, sulfides formed as veinlets along host rock fractures. The primary sulfides include pyrrhotite, pentlandite, and secondary digenite and pyrite. The primary sulfide content increases with increasing size and amount of clinopyroxene in host rocks. Associated chromian spinels in host ultramafics display disseminated and massive textures. Discussion Generally, mineralization in ophiolites is controlled by two major steps: a partial melting of upper mantle rocks and b crystal fractionation in a magma chamber (Rajabzadeh and Moosavinasab, 2013. The chemical compositions of the analyzed minerals were then used in estimating the conditions in these two steps. The composition of chromian spinel corresponds to chromite of boninitic melts formed in supra-subduction zone environments. Boninitic melts are produced at high degrees of partial melting of mantle peridotites in the presence of water (Edwards et al., 2002. Silicates of the host rocks are mainly clinopyroxene (diopside and augite of the composition Wo47.50 En45.48 Fs3.4, olivine Fo92 and orthopyroxene (enstatite - bronzite of En85 to En88. The main host ultramafic rocks of sulfides are wehrlite and clinopyroxenite, indicating that the sulfide saturation occurred during magmatic evolution of these rocks. This suggests that sulfide mineralization will occur in the northern part the ophiolite. The sulfide grains are anhedral, amoeboidal in shape, and appeared as disseminated interstitial phases, indicating that they were trapped as liquid phases during increase in sulfur fugacity and decrease in

  4. Improved sodium-storage performance of stannous sulfide@reduced graphene oxide composite as high capacity anodes for sodium-ion batteries

    Science.gov (United States)

    Wu, Lin; Lu, Haiyan; Xiao, Lifen; Ai, Xinping; Yang, Hanxi; Cao, Yuliang

    2015-10-01

    Stannous sulfide@reduced graphene oxide (SnS@RGO) composite is successfully synthesized via a facile precipitation route. The structural and morphological characterizations reveal SnS@RGO composites are composed of SnS nanoparticles of the size 5-10 nm, which are uniformly anchored on the surface of RGO. The electrochemical measurements demonstrate the reversible capacity of the SnS@RGO composite - that includes contributions from the conversion reaction of SnS to Sn and NaxS and the alloying reaction of Sn to NaxSn. The SnS@RGO electrode exhibits a reversible capacity of 457 mAh g-1 at 20 mA g-1, superior cycling stability (94% capacity retention over 100 cycles at 100 mA g-1) and adequate rate performance. Compared to the neat SnS nanoparticles, the enhanced electrochemical performance of the SnS@RGO composite is primarily due to the incorporation of RGO as a highly conductive, flexible component as well as possessing a large available surface area, which provides desirable properties such as improved electronic contact between active materials, aggregation suppression of intermediate products, and alleviation of the volume change during sodiation and desodiation. Encouraging experimental results suggest that the SnS@RGO composite is a promising material to achieve a high-capacity and stable anode for NIBs.

  5. Spatial distribution and cellular composition of adult brain proliferative zones in the teleost, Gymnotus omarorum

    Directory of Open Access Journals (Sweden)

    Valentina eOlivera-Pasilio

    2014-09-01

    Full Text Available Proliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described. To address this, we used double thymidine analog pulse-chase labeling of proliferating cells to identify brain proliferation zones, characterize their cellular composition, and analyze the fate of newborn cells in adult G. omarorum. Short thymidine analog chase periods revealed the ubiquitous distribution of adult brain proliferation, similar to other teleosts, particularly Apteronotus leptorhynchus. Proliferating cells were abundant at the ventricular-subventricular lining of the ventricular-cisternal system, adjacent to the telencephalic subpallium, the diencephalic preoptic region and hypothalamus, and the mesencephalic tectum opticum and torus semicircularis. Extraventricular proliferation zones, located distant from the ventricular-cisternal system surface, were found in all divisions of the rombencephalic cerebellum. We also report a new adult proliferation zone at the caudal-lateral border of the electrosensory lateral line lobe. All proliferation zones showed a heterogeneous cellular composition. The use of short (24hs and long (30d chase periods revealed abundant fast cycling cells (potentially intermediate amplifiers, sparse slow cycling (potentially stem cells, cells that appear to have entered a quiescent state, and cells that might correspond to migrating newborn neural cells. Their abundance and migration distance differed among proliferation zones: greater numbers and longer range and/or pace of migrating cells were associated with subpallial and cerebellar proliferation zones.

  6. Soil organic matter content and composition in different pedoclimatic zones of Bulgaria

    OpenAIRE

    Biser Hristov; Ekaterina Filcheva

    2017-01-01

    The present paper focused on content, quality and composition of soil organic matter in different pedoclimatic zones of Bulgaria. The country has temperate continental climate with Mediterranean influence. There are six combinations of soil temperature and moisture regimes over the territory of Bulgaria, such as Thermic-Xeric, Mesic-Xeric, Mesic-Ustic, Mesic-Udic, Cryic-Udic and Pergelic – Udic. Typical soil types for Bulgaria are Chernozems, Luvisols. Vertisols, Cambisols, Phaeozems, Leptos...

  7. Geology, petrography, geochemistry, and genesis of sulfide-rich pods in the Lac des Iles palladium deposits, western Ontario, Canada

    Science.gov (United States)

    Duran, Charley J.; Barnes, Sarah-Jane; Corkery, John T.

    2016-04-01

    The Lac des Iles Pd deposits are known for their Pd-rich sulfide-poor mineralization. However, previously undocumented sulfide-rich pods also occur within the intrusion that hosts the deposits. Given the complex magmatic and hydrothermal history of the mineralization at Lac des Iles, the sulfide-rich pods could have crystallized from magmatic sulfide liquids or precipitated from hydrothermal fluids. Sulfide-rich pods occur throughout the stratigraphy, in all rock types, and along comagmatic shear zones, and contain net-textured to massive sulfides. They can be divided into four main groups based on the variation in mineral assemblages: (1) pyrrhotite-pentlandite ± pyrite-chalcopyrite-magnetite-ilmenite; (2) chalcopyrite ± pyrrhotite-pentlandite-pyrite-magnetite-ilmenite; (3) pyrite ± pentlandite-chalcopyrite-pyrrhotite-magnetite-ilmenite; and (4) magnetite ± ilmenite-pyrrhotite-pentlandite-pyrite-chalcopyrite. Whole rock metal contents and S isotopic compositions do not change with the amount of pyrite present, except for slight enrichments in As and Bi. The presence of an essentially magmatic sulfide mineral assemblage (pyrrhotite-pentlandite ± chalcopyrite) with pentlandite exsolution flames in pyrrhotite in some pods suggests that the pods crystallized from magmatic sulfide liquids. The very low Cu contents of the pods suggests that they are mainly cumulates of monosulfide solid solution (MSS). We propose a model whereby sulfide liquids were concentrated into dilation zones prior to crystallizing cumulus MSS. Intermediate solid solution crystallized from the fractionated liquids at the edges of some pods leaving residual liquids enriched in Pt, Pd, Au, As, Bi, Sb, and Te. These residual liquids are no longer associated with the pods. During subsequent alteration, pyrite replaced MSS/pyrrhotite, but this did not affect the platinum-group element contents of the pods.

  8. An ultrasensitive electrochemiluminescence sensor based on reduced graphene oxide-copper sulfide composite coupled with capillary electrophoresis for determination of amlodipine besylate in mice plasma.

    Science.gov (United States)

    Wei, Yanfen; Wang, Hao; Sun, Shuangjiao; Tang, Lifu; Cao, Yupin; Deng, Biyang

    2016-12-15

    A new electrochemiluminescence (ECL) sensor based on reduced graphene oxide-copper sulfide (rGO-CuS) composite coupled with capillary electrophoresis (CE) was constructed for the ultrasensitive detection of amlodipine besylate (AML) for the first time. In this work, rGO-CuS composite was synthesized by one-pot hydrothermal method and used for electrode modification. The electrochemical and ECL behaviors of the sensor were investigated. More than 5-fold enhance in ECL intensity was observed after modified with rGO-CuS composite. The results can be ascribed to the presence of rGO-CuS composite on the electrode surface that facilitates the electron transfer rate between the electroactive center of Ru(bpy)3(2+) and the electrode. The ECL sensor was coupled with CE to improve the selectivity and the CE-ECL parameters that affect separation and detection were optimized. Under the optimum conditions, the linear ranges for AML was 0.008-5.0μg/mL with a detection limit of 2.8ng/mL (S/N=3). The method displayed the advantages of high sensitivity, good selectivity, wide linear range, low detection limit and fine reproducibility, and was used to analyze AML in mice plasma with a satisfactory result, which holds a great potential in the field of pharmaceutical analysis.

  9. Sulfide composition and microthermometry of fluid inclusions in the leg 111 sheeted dike section of Ocean Drilling Program hole 504B, Costa Rica rift

    Energy Technology Data Exchange (ETDEWEB)

    Schoeps, D. (Technische Hochschule Aachen (West Germany)); Herzig, P.M. (Univ. of Toronto, Ontario (Canada))

    1990-06-10

    Hole 504B of the Ocean Drilling Program is dedicated to the study of crustal structure and hydrothermal processes in 5.9-m.y.-old oceanic basement. Continuing the work of previous legs, hole 504B was extended 212.3 m to a total depth of 1,562.3 m below seafloor (bsf) during leg 111 in 1986. Quartz-sulfide veins occur at a depth of 1,369-1,388 m bsf in basalts of the sheeted dike complex. The ore minerals are predominantly pyrite, less chalcopyrite, rare Co-rich Cu-Fe-S phases, and a thiospinel (linnaeite/carrollite). Microprobe analyses yield a high Co content in zoned vein pyrites (>8 wt%) as well as in the Cu-Fe-S phases (>5 wt%). Up to 35.8 wt% CO was detected in the thiospinel. A Co/Ni ratio of > 100 distinguishes the vein pyrite from pyrite in the basaltic wall rock and from pyrite formed as an alteration product of olivine (Co/Ni < 5). The Co/Ni ratios correlate positively with Cu and negatively with As. Co-rich, nonstoichiometric Cu-Fe-S sulfides in chalcopyrite are interpreted as metastable phases which have been quenched at a high temperature and prohibited from exsolution of the stable products chalcopyrite and pyrite. Fluid inclusions in quartz from the quartz-sulfide veins are two-phase and vary from liquid- to vapor-dominated. Their salinities range from 4.2 to 7.2 wt% equivalent NaCl and average 5.5 wt%. Pressure (360 bars) corrected average filling temperatures vary from 271 to 408 C with a maximum of 486 C. This is consistent with calculated quartz formation temperatures for a single quartz separate (+4.2{per thousand} {delta}{sup 18}O) using oxygen isotope thermometry. The {delta}{sup 18}O value of the hydrothermal fluid was determined to be +1.7{per thousand}. The temperature data indicate fluid alteration of the sheeted dikes at about 350 to 500 C.

  10. Hydrology controls dissolved organic matter export and composition in an Alpine stream and its hyporheic zone.

    Science.gov (United States)

    Fasching, Christina; Ulseth, Amber J; Schelker, Jakob; Steniczka, Gertraud; Battin, Tom J

    2016-03-01

    Streams and rivers transport dissolved organic matter (DOM) from the terrestrial environment to downstream ecosystems. In light of climate and global change it is crucial to understand the temporal dynamics of DOM concentration and composition, and its export fluxes from headwaters to larger downstream ecosystems. We monitored DOM concentration and composition based on a diurnal sampling design for 3 years in an Alpine headwater stream. We found hydrologic variability to control DOM composition and the coupling of DOM dynamics in the streamwater and the hyporheic zone. High-flow events increased DOM inputs from terrestrial sources (as indicated by the contributions of humic- and fulvic-like fluorescence), while summer baseflow enhanced the autochthonous imprint of DOM. Diurnal and seasonal patterns of DOM composition were likely induced by biological processes linked to temperature and photosynthetic active radiation (PAR). Floods frequently interrupted diurnal and seasonal patterns of DOM, which led to a decoupling of streamwater and hyporheic water DOM composition and delivery of aromatic and humic-like DOM to the streamwater. Accordingly, DOM export fluxes were largely of terrigenous origin as indicated by optical properties. Our study highlights the relevance of hydrologic and seasonal dynamics for the origin, composition and fluxes of DOM in an Alpine headwater stream.

  11. Distribution and Composition of Thiotrophic Mats in the Hypoxic Zone of the Black Sea (150–170 m Water Depth, Crimea Margin)

    Science.gov (United States)

    Jessen, Gerdhard L.; Lichtschlag, Anna; Struck, Ulrich; Boetius, Antje

    2016-01-01

    At the Black Sea chemocline, oxygen- and sulfide-rich waters meet and form a niche for thiotrophic pelagic bacteria. Here we investigated an area of the Northwestern Black Sea off Crimea close to the shelf break, where the chemocline reaches the seafloor at around 150–170 m water depth, to assess whether thiotrophic bacteria are favored in this zone. Seafloor video transects were carried out with the submersible JAGO covering 20 km2 on the region between 110 and 200 m depth. Around the chemocline we observed irregular seafloor depressions, covered with whitish mats of large filamentous bacteria. These comprised 25–55% of the seafloor, forming a belt of 3 km width around the chemocline. Cores from the mats obtained with JAGO showed higher accumulations of organic matter under the mats compared to mat-free sediments. The mat-forming bacteria were related to Beggiatoa-like large filamentous sulfur bacteria based on 16S rRNA sequences from the mat, and visual characteristics. The microbial community under the mats was significantly different from the surrounding sediments and enriched with taxa affiliated with polymer degrading, fermenting and sulfate reducing microorganisms. Under the mats, higher organic matter accumulation, as well as higher remineralization and radiotracer-based sulfate reduction rates were measured compared to outside the mat. Mat-covered and mat-free sediments showed similar degradability of the bulk organic matter pool, suggesting that the higher sulfide fluxes and subsequent development of the thiotrophic mats in the patches are consequences of the accumulation of organic matter rather than its qualitative composition. Our observations suggest that the key factors for the distribution of thiotrophic mat-forming communities near to the Crimean shelf break are hypoxic conditions that (i) repress grazers, (ii) enhance the accumulation and degradation of labile organic matter by sulfate-reducers, and (iii) favor thiotrophic filamentous bacteria

  12. Distribution and Composition of Thiotrophic Mats in the Hypoxic Zone of the Black Sea (150-170 m Water Depth, Crimea Margin).

    Science.gov (United States)

    Jessen, Gerdhard L; Lichtschlag, Anna; Struck, Ulrich; Boetius, Antje

    2016-01-01

    At the Black Sea chemocline, oxygen- and sulfide-rich waters meet and form a niche for thiotrophic pelagic bacteria. Here we investigated an area of the Northwestern Black Sea off Crimea close to the shelf break, where the chemocline reaches the seafloor at around 150-170 m water depth, to assess whether thiotrophic bacteria are favored in this zone. Seafloor video transects were carried out with the submersible JAGO covering 20 km(2) on the region between 110 and 200 m depth. Around the chemocline we observed irregular seafloor depressions, covered with whitish mats of large filamentous bacteria. These comprised 25-55% of the seafloor, forming a belt of 3 km width around the chemocline. Cores from the mats obtained with JAGO showed higher accumulations of organic matter under the mats compared to mat-free sediments. The mat-forming bacteria were related to Beggiatoa-like large filamentous sulfur bacteria based on 16S rRNA sequences from the mat, and visual characteristics. The microbial community under the mats was significantly different from the surrounding sediments and enriched with taxa affiliated with polymer degrading, fermenting and sulfate reducing microorganisms. Under the mats, higher organic matter accumulation, as well as higher remineralization and radiotracer-based sulfate reduction rates were measured compared to outside the mat. Mat-covered and mat-free sediments showed similar degradability of the bulk organic matter pool, suggesting that the higher sulfide fluxes and subsequent development of the thiotrophic mats in the patches are consequences of the accumulation of organic matter rather than its qualitative composition. Our observations suggest that the key factors for the distribution of thiotrophic mat-forming communities near to the Crimean shelf break are hypoxic conditions that (i) repress grazers, (ii) enhance the accumulation and degradation of labile organic matter by sulfate-reducers, and (iii) favor thiotrophic filamentous bacteria

  13. Pyrrhotite mineralization as a search criterion for sulfide deposits at sediment-covered spreading centers

    Science.gov (United States)

    Bogdanova, O. Yu.; Lein, A. Yu.; Dara, O. M.; Ozhogina, E. G.; Lisitzin, A. P.

    2016-09-01

    Pyrrhotite ores forming the hydrothermal vents of the Hydrothermal Hills in the Southern Trough of the Guaymas depression were studied. A series of features pointing to the occurrence of surface and buried sulfide deposits of pyrrhotite mineralization was revealed: the presence of pyrrhotite associations to hydrocarbons of oil series; low concentrations of Cu, Zn, and Pb; the enrichment of sulfur of pyrrhotite and hydrogen sulfide of hydrothermal solutions in heavy 34S isotope by 5-7%; and the heavy isotope composition of carbon in naphthoid compounds. The results obtained allow one to suggest searching for large sulfide deposits at active rifts of high spreading and sedimentation rates, i.e., at near-continental rifts of the humid zone of avalanche sedimentation.

  14. Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

    Directory of Open Access Journals (Sweden)

    L. P. Golobokova

    2016-01-01

    Full Text Available Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE, namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3 and Mirny (0,50 ág / m3. The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1. It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of

  15. Laboratory Measurements of Synthetic Pyroxenes and their Mixtures with Iron Sulfides as Inorganic Refractory Analogues for Rosetta/VIRTIS' Surface Composition Analysis of 67P/CG

    Science.gov (United States)

    Markus, Kathrin; Arnold, Gabriele; Moroz, Ljuba; Henckel, Daniela; Kappel, David; Capaccioni, Fabrizio; Filacchione, Gianrico; Schmitt, Bernard; Tosi, Federico; Érard, Stéphane; Bockelee-Morvan, Dominique; Leyrat, Cedric; VIRTIS Team

    2016-10-01

    The Visible and InfraRed Thermal Imaging Spectrometer VIRTIS on board Rosetta provided 0.25-5.1 µm spectra of 67P/CG's surface (Capaccioni et al., 2015). Thermally corrected reflectance spectra display a low albedo of 0.06 at 0.65 µm, different red VIS and IR spectral slopes, and a broad 3.2 µm band. This absorption feature is due to refractory surface constituents attributed to organic components, but other refractory constituents influence albedo and spectral slopes. Possible contributions of inorganic components to spectral characteristics and spectral variations across the surface should be understood based on laboratory studies and spectral modeling. Although a wide range of silicate compositions was found in "cometary" anhydrous IDPs and cometary dust, Mg-rich crystalline mafic minerals are dominant silicate components. A large fraction of silicate grains are Fe-free enstatites and forsterites that are not found in terrestrial rocks but can be synthesized in order to provide a basis for laboratory studies and comparison with VIRTIS data. We report the results of the synthesis, analyses, and spectral reflectance measurements of Fe-free low-Ca pyroxenes (ortho- and clinoenstatites). These minerals are generally very bright and almost spectrally featureless. However, even trace amounts of Fe-ions produce a significant decrease in the near-UV reflectance and hence can contribute to slope variations. Iron sulfides (troilite, pyrrhotite) are among the most plausible phases responsible for the low reflectance of 67P's surface from the VIS to the NIR. The darkening efficiency of these opaque phases is strongly particle-size dependent. Here we present a series of reflectance spectra of fine-grained synthetic enstatite powders mixed in various proportions with iron sulfide powders. The influence of dark sulfides on reflectance in the near-UV to near-IR spectral ranges is investigated. This study can contribute to understand the shape of reflectance spectra of 67P

  16. Cohesive Zone Model Based Numerical Analysis of Steel-Concrete Composite Structure Push-Out Tests

    Directory of Open Access Journals (Sweden)

    J. P. Lin

    2014-01-01

    Full Text Available Push-out tests were widely used to determine the shear bearing capacity and shear stiffness of shear connectors in steel-concrete composite structures. The finite element method was one efficient alternative to push-out testing. This paper focused on a simulation analysis of the interface between concrete slabs and steel girder flanges as well as the interface of the shear connectors and the surrounding concrete. A cohesive zone model was used to simulate the tangential sliding and normal separation of the interfaces. Then, a zero-thickness cohesive element was implemented via the user-defined element subroutine UEL in the software ABAQUS, and a multiple broken line mode was used to define the constitutive relations of the cohesive zone. A three-dimensional numerical analysis model was established for push-out testing to analyze the load-displacement curves of the push-out test process, interface relative displacement, and interface stress distribution. This method was found to accurately calculate the shear capacity and shear stiffness of shear connectors. The numerical results showed that the multiple broken lines mode cohesive zone model could describe the nonlinear mechanical behavior of the interface between steel and concrete and that a discontinuous deformation numerical simulation could be implemented.

  17. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O' Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah S.

    2008-09-11

    This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples.

  18. Composition of organic matter in sediments of the oxygen minimum zone of the Northeastern Mexican Pacific

    Science.gov (United States)

    Juarez, M.; Sanchez, A.; Aguiñiga-García, S.; Lara-Mendoza, A.

    2013-05-01

    Total organic carbon (TOC) content, total nitrogen (TN) content, elemental (C and N), and isotopic (δ13C-TOC) composition of organic matter derived from both marine and terrestrial sources constrain the relative contributions from marine productivity, the mangroves, and the continental wind erosion of 36 carbonate-free surface sediments along the southwestern coast of the Baja California Peninsula. In general, the spatial patterns of TOC, TN, C:N ratio and δ13C-TOC are similar. The maximum content of TOC (14.5%) and TN (1.6%) were measured inside the oxygen minimum zone (OMZ). The stable carbon isotopic compositions were enriched in 12C in surface sediments at suboxic sites within the OMZ. The C:N ratio and δ13C-TOC values indicated that the organic sediment material is predominantly of marine origin, with a minor contribution from the terrestrial source or mangroves. In the stations near to the coast, the high values of the C:N ratio and the depleted 13C values suggest a proportionally greater accumulation of terrestrial organic matter. The terrestrial-derived organic carbon content is 40% at the stations near to the coast, based on a Mixing Model of End Members. Keywords: Total organic carbon, total nitrogen, carbon stable isotopes, oxygen minimum zone, northeastern Pacific.

  19. He, Ne and Ar isotope compositions of fluid inclusions in hy-drothermal sulfides from the TAG hydrothermal field, Mid-Atlantic Ridge

    Institute of Scientific and Technical Information of China (English)

    ZENG; Zhigang; (

    2001-01-01

    [1]Rona, P. A. , Klinkhammer, G. , Nelsen, T. A. et al. , Black smokers, massive sulphides and vent biota at the Mid-Atlantic Ridge, Nature, 1986, 321: 33.[2]Edmonds, H. N. , German, C. R. , Green, D. R. H. et al. , Continuation of the hydrothermal fluid chemistry time series at TAG, and the effects of ODP drilling, Geophys. Res. Lett., 1996, 23: 3487.[3]Charlou, J. L. , Donval, J. P. , Jean-Baptiste, P. et al. , Gases and helium isotopes in high temperature solutions sampled before and after ODP Leg158 drilling at TAG hydrothermal field (26°N, MAR), Geophys. Res. Lett., 1996, 23: 3491. [4]Rudnicki, M. D. , Elderfield, H. , Helium, radon and manganese at the TAG and Snakepit hydrothermal vent fields, 26°and 23°N, Mid-Atlantic Ridge, Earth Planet. Sci. Lett., 1992, 113: 307. [5]Butterfield, D. A. , Massoth, G. J. , McDuff, R. E. et al. , Geochemistry of fluids from Axial Seamount hydrothermal emissions study vent field, Juan de Fuca Ridge: Subseafloor boiling and subsequent fluid-rock interaction, Journal of Geophysical Research, 1990, 95: 12895. [6]Baker, E. T. , Lupton, J. E. , Changes in submarine hydrothermal 3He/heat ratios as an indicator of magmatic/tectonic activity, Nature, 1990, 346: 556. [7]Jean-Baptiste, P. , Fouquet, Y. , Abundance and isotopic composition of helium in hydrothermal sulfides from the East Pacific Rise at 13°N, Geochimica et Cosmochimica Acta, 1996, 60: 87. [8]Stuart, F. M. , Turner, G. , Duckworth, R. C. et al. , Helium isotopes as tracers of trapped hydrothermal fluids in ocean-floor sulfides, Geology, 1994, 22: 823. [9]Stuart, F. M. , Duckworth, R. , Turner, G. et al. , Helium and sulfur isotopes in sulfide minerals from Middle Valley, Northern Juan de Fuca Ridge, Proceedings of the Ocean Drilling Program, Scientific Results, 1994, 139: 387. [10]Turner, G. , Stuart, F. , Helium/heat ratios and deposition temperatures of sulphides from the ocean floor, Nature, 1992, 357: 581.[11

  20. Differences in the Composition of Archaeal Communities in Sediments from Contrasting Zones of Lake Taihu

    Science.gov (United States)

    Fan, Xianfang; Xing, Peng

    2016-01-01

    In shallow lakes, different primary producers might impact the physiochemical characteristics of the sediment and the associated microbial communities. Until now, little was known about the features of sediment Archaea and their variation across different primary producer-dominated ecosystems. Lake Taihu provides a suitable study area with cyanobacteria- and macrophyte-dominated zones co-occurring in one ecosystem. The composition of the sediment archaeal community was assessed using 16S rRNA gene amplicon sequencing technology, based on which the potential variation with respect to the physiochemical characteristics of the sediment was analyzed. Euryarchaeota (30.19% of total archaeal sequences) and Bathyarchaeota (28.00%) were the two most abundant phyla, followed by Crenarchaeota (11.37%), Aigarchaeota (10.24%) and Thaumarchaeota (5.98%). The differences found in the composition of the archaeal communities between the two zones was significant (p = 0.005). Sediment from macrophyte-dominated zones had high TOC and TN content and an abundance of archaeal lineages potentially involved in the degradation of complex organic compounds, such as the order Thermoplasmatales. In the area dominated by Cyanobacteria, archaeal lineages related to sulfur metabolism, for example, Sulfolobales and Desulfurococcales, were significantly enriched. Among Bathyarchaeota, subgroups MCG-6 and MCG-15 were significantly accumulated in the sediment of areas dominated by macrophytes whereas MCG-4 was consistently dominant in both type of sediments. The present study contributes to the knowledge of sediment archaeal communities with different primary producers and their possible biogeochemical functions in sediment habitats. PMID:27708641

  1. Re-Os isotope measurements of single sulfide inclusions in a Siberian diamond and its nitrogen aggregation systematics

    Science.gov (United States)

    Pearson, D. G.; Shirey, S. B.; Bulanova, G. P.; Carlson, R. W.; Milledge, H. J.

    1999-03-01

    We have measured the Re-Os isotopic compositions of individual syngenetic sulfide inclusions from three different growth zones within a central cross section plate cut from a single Siberian diamond. Individual sulfides in their diamond host were isolated by laser cutting. The sulfides, and hence the different growth zones of the diamond have been suggested to differ in age by up to 2 Ga on the basis of their Pb isotope compositions. Re-Os model ages of the four inclusions range from 3.1 ± 0.3 to 3.5 ± 0.3 Ga and suggest a Middle Archaean age for the diamond. A sulfide inclusion in the rim of the diamond is very different in elemental composition from those of the core and intermediate zones. It is enriched in Os, Re, Pb, and Zn and has more radiogenic Os and Pb isotopes. The inclusion is connected to the surface of the diamond by a healed crack, revealed by cathodoluminescence. The compositional distinction may be caused either by postformational interaction between an ancient sulfide and a fluid, possibly at the time of kimberlite eruption, or later stage growth of new diamond plus sulfide. Such chemical complexities, and the presence of healed fractures within the host diamond, emphasize the desirability of analyzing individual inclusions from well-characterized diamonds if isotope data for inclusions are to be better understood. Nitrogen contents and aggregation state in the core and intermediate zone of the host diamond closely approximate theoretically calculated isotherms based on consideration of experimentally determined nitrogen aggregation kinetics. The nitrogen content of the rim diamond is too low to obtain spectra that allow accurate deconvolution of relative aggregation levels for use in residence time calculations. The aggregation state of nitrogen in the core and intermediate growth zones is compatible with a long, ca. 3 Ga mantle residence time at normal lithospheric temperatures. The similarity of the sulfide inclusion Re-Os model ages to the

  2. Sulfide oxidation as a process for the formation of copper-rich magmatic sulfides

    Science.gov (United States)

    Wohlgemuth-Ueberwasser, Cora C.; Fonseca, Raúl O. C.; Ballhaus, Chris; Berndt, Jasper

    2013-01-01

    Typical magmatic sulfides are dominated by pyrrhotite and pentlandite with minor chalcopyrite, and the bulk atomic Cu/Fe ratio of these sulfides is typically less than unity. However, there are rare magmatic sulfide occurrences that are dominated by Cu-rich sulfides (e.g., bornite, digenite, and chalcopyrite, sometimes coexisting with metallic Cu) with atomic Cu/Fe as high as 5. Typically, these types of sulfide assemblages occur in the upper parts of moderately to highly fractionated layered mafic-ultramafic intrusions, a well-known example being the Pd/Au reef in the Upper Middle Zone of the Skaergaard intrusion. Processes proposed to explain why these sulfides are so unusually rich in Cu include fractional crystallization of Fe/(Ni) monosulfide and infiltration of postmagmatic Cu-rich fluids. In this contribution, we explore and experimentally evaluate a third possibility: that Cu-rich magmatic sulfides may be the result of magmatic oxidation. FeS-dominated Ni/Cu-bearing sulfides were equilibrated at variable oxygen fugacities in both open and closed system. Our results show that the Cu/Fe ratio of the sulfide melt increases as a function of oxygen fugacity due to the preferential conversion of FeS into FeO and FeO1.5, and the resistance of Cu2S to being converted into an oxide component even at oxygen fugacities characteristic of the sulfide/sulfate transition (above FMQ + 1). This phenomenon will lead to an increase in the metal/S ratio of a sulfide liquid and will also depress its liquidus temperature. As such, any modeling of the sulfide liquid line of descent in magmatic sulfide complexes needs to address this issue.

  3. Clinopyroxene in postshield Haleakala ankaramite: 2. Texture, compositional zoning and supersaturation in the magma

    Science.gov (United States)

    Welsch, Benoit; Hammer, Julia; Baronnet, Alain; Jacob, Samantha; Hellebrand, Eric; Sinton, John

    2016-01-01

    We investigated the external morphologies and internal compositional zoning patterns of clinopyroxene phenocrysts in an ankaramite of Haleakala volcano (Hawaii) to constrain magma crystallization conditions in the volcano's postshield stage. The phenocrysts are characterized by euhedral faceted morphologies and crystallographically coherent subcrystals. Quantitative EPMA and X-ray element mapping reveal two domains within the crystals: porous, Si-Mg-Ca-Cr-rich zones associated with the forms {100}, {010} and {110}, and nonporous, Al-Ti-Na-rich zones associated with the forms {-111}. The chemical variations, internal porosity and parallel subcrystals are consistent with nonconcentric crystal growth at varying degrees of supersaturation. We infer that initial growth occurred in a diffusion-limited regime to produce dendritic crystals; subsequent growth was markedly slower, with lesser supersaturation allowing dendrites to infill and produce polyhedral external morphologies. This sequence promoted the evolution of crystals from an hourglass shape with dominant {-111} forms, to sector-zoned euhedral crystals in which elements were partitioned according to: (Al + Ti + Na){-111} = (Si + Mg + Cr + Ca){110},{100},{010}. Infilling of dendritic crystals occurred to a greater extent on faster-growing sectors and was interrupted by the eruption, resulting in porosity of the slower-growing {hk0} sectors. Outermost Na-poor rims formed on all sectors due to slower growth rate under interface-limited conditions. Paradoxically, high levels of supersaturation producing large crystals of clinopyroxene (and olivine) are indicated in the volcano's deep-seated reservoir and lower degrees of supersaturation characterize syn-eruptive crystal growth. The presence of vapor bubbles within the melt-filled crystal embayments and inclusions suggests rapid clinopyroxene growth caused volatile saturation and reservoir pressurization, leading to eruption of the ankaramite.

  4. High-Resolution P'P' Precursor Imaging of Nazca-South America Plate Boundary Zones and Inferences for Transition Zone Temperature and Composition

    Science.gov (United States)

    Gu, Y. J.; Schultz, R.

    2013-12-01

    Knowledge of upper mantle transition zone stratification and composition is highly dependent on our ability to efficiently extract and properly interpret small seismic arrivals. A promising high-frequency seismic phase group particularly suitable for a global analysis is P'P' precursors, which are capable of resolving mantle structures at vertical and lateral resolution of approximately 5 and 200 km, respectively, owing to their shallow incidence angle and small, quasi-symmetric Fresnel zones. This study presents a simultaneous analysis of SS and P'P' precursors based on deconvolution, Radon transform and depth migration. Our multi-resolution survey of the mantle near Nazca-South America subduction zone reveals both olivine and garnet related transitions at depth below 400 km. We attribute a depressed 660 to thermal variations, whereas compositional variations atop the upper-mantle transition zone are needed to explain the diminished or highly complex reflected/scattered signals from the 410 km discontinuity. We also observe prominent P'P' reflections within the transition zone, especially near the plate boundary zone where anomalously high reflection amplitudes result from a sharp (~10 km thick) mineral phase change resonant with the dominant frequency of the P'P' precursors. Near the base of the upper mantle, the migration of SS precursors shows no evidence of split reflections near the 660-km discontinuity, but potential majorite-ilmenite (590-640 km) and ilmenite-perovskite transitions (740-750 km) are identified based on similarly processed high-frequency P'P' precursors. At nominal mantle temperatures these two phase changes may be seismically indistinguishable, but colder mantle conditions from the descending Nazca plate, the presence of water and variable Fe contents may cause sufficient separation for a reliable analysis. In addition, our preliminary results provide compelling evidence for multiple shallow lower-mantle reflections (at ~800 km) along the

  5. Surfactant-controlled composition and crystal structure of manganese(II sulfide nanocrystals prepared by solvothermal synthesis

    Directory of Open Access Journals (Sweden)

    Elena Capetti

    2015-12-01

    Full Text Available We investigated how the outcome of the solvothermal synthesis of manganese(II sulfide (MnS nanocrystals (NCs is affected by the type and amount of long chain surfactant present in the reaction mixture. Prompted by a previous observation that a larger than stoichiometric amount of sulfur is required [Puglisi, A.; Mondini, S.; Cenedese, S.; Ferretti, A. M.; Santo, N.; Ponti A. Chem. Mater. 2010, 22, 2804–2813], we carried out a wide set of reactions using Mn(II carboxylates and Mn2(CO10 as precursors with varying amounts of sulfur and carboxylic acid. MnS NCs were obtained provided that the S/Mn ratio was larger than the L/Mn ratio, otherwise MnO NCs were produced. Since MnS can crystallize in three distinct phases (rock salt α-MnS, zincblende β-MnS, and wurtzite γ-MnS, we also investigated whether the surfactant affected the NC polymorphism. We found that MnS polymorphism can be controlled by appropriate selection of the surfactant. γ-MnS nanocrystals formed when a 1:2 mixture of long chain carboxylic acid and amine was used, irrespective of the presence of carboxylic acid as a free surfactant or ligand in the metal precursor. When we used a single surfactant (carboxylic acid, alcohol, thiol, amine, α-MnS nanocrystals were obtained. The peculiar role of the amine seems to be related to its basicity. The nanocrystals were characterized by TEM and electron diffraction; ATR-FTIR spectroscopy provided information about the surfactants adsorbed on the NCs.

  6. Fluid-mediated metal transport in subduction zones and its link to arc-related giant ore deposits: Constraints from a sulfide-bearing HP vein in lawsonite eclogite (Tianshan, China)

    Science.gov (United States)

    Li, Ji-Lei; Gao, Jun; John, Timm; Klemd, Reiner; Su, Wen

    2013-11-01

    High-pressure (HP) veins in eclogites provide insight into element mobility during fluid-rock interaction in subduction zones. Here, we present a petrological-geochemical study of a sulfide-bearing HP vein and its massive lawsonite eclogite host rock from the Chinese Tianshan (ultra-)high-pressure/low-temperature metamorphic belt. The omphacite-dominated vein is enveloped by a garnet-poor, sulfide-bearing eclogite-facies reaction selvage. Lawsonite, garnet, omphacite, glaucophane and other HP minerals occur as inclusions in pyrite porphyroblasts of the selvage rock, indicating that the selvage formed prograde under eclogite-facies conditions. Relicts of wall-rock garnet (Grt_I) cores in recrystallized selvage garnet (Grt_II) close to the wall rock and the Ca distribution in Grt_II, which images the overgrown selvage matrix, indicate that the selvage formed due to dissolution-precipitation processes as a consequence of fluid-rock interaction of the wall rock eclogite with the vein-forming fluid. The peak metamorphic P-T conditions of the wall-rock eclogite are estimated at ca. 590 °C and 23 kbar. Mass-balance calculations indicate that the reaction selvage experienced: (1) a depletion of the large-ion lithophile elements (K-Rb-Ba) of up to 100% relative to their concentrations in the wall-rock eclogite; (2) a moderate depletion of the HREE and some transition metal elements including Fe, Cu, Ni, Zn, Co, Cr, and Mn (10-40%); (3) a significant enrichment of CaO (up to 50-80%), Sr (up to ˜200%), Pb (up to ˜170%) and S (up to ˜210%); (4) a slight to moderate enrichment of the LREE (10-20%) and MREE (0-40%); whereas (5) the HFSE show no significant variations.

  7. NOVEL COMPOSITE HYDROGEN-PERMEABLE MEMBRANES FOR NON-THERMAL PLASMA REACTORS FOR THE DECOMPOSITION OF HYDROGEN SULFIDE

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Ji-Jun Zhang; Guibing Zhao; Robyn J. Alcanzare; Linna Wang; Ovid A. Plumb

    2004-07-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant. This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655 x 10{sup -6} m{sup 3}/s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C{sub 2} and C{sub 3} hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50%-60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a

  8. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-10-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. A pulsed corona discharge (PCD) reactor has been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. A nonthermal plasma cannot be produced in pure H{sub 2}S with our reactor geometry, even at discharge voltages of up to 30 kV, because of the high dielectric strength of pure H{sub 2}S ({approx}2.9 times higher than air). Therefore, H{sub 2}S was diluted in another gas with lower breakdown voltage (or dielectric strength). Breakdown voltages of H{sub 2}S in four balance gases (Ar, He, N{sub 2} and H{sub 2}) have been measured at different H{sub 2}S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H{sub 2}S and the balance gas. H{sub 2}S conversion and the reaction energy efficiency depend on the balance gas and H{sub 2}S inlet concentrations. With increasing H{sub 2}S concentrations, H{sub 2}S conversion initially increases, reaches a maximum, and then decreases. H{sub 2}S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gases, such as N{sub 2} and H{sub 2}. These observations can be explained by the proposed reaction mechanism of H{sub 2}S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H{sub 2}S into hydrogen and sulfur.

  9. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibing Zhao; Sanil John

    2006-09-30

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Several pulsed corona discharge (PCD) reactors have been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. Visual observation shows that the corona is not uniform throughout the reactor. The corona is stronger near the top of the reactor in argon, while nitrogen and mixtures of argon or nitrogen with H{sub 2}S produce stronger coronas near the bottom of the reactor. Both of these effects appear to be explainable base on the different electron collision interactions with monatomic versus polyatomic gases. A series of experiments varying reactor operating parameters, including discharge capacitance, pulse frequency, and discharge voltage were performed while maintaining constant power input to the reactor. At constant reactor power input, low capacitance, high pulse frequency, and high voltage operation appear to provide the highest conversion and the highest energy efficiency for H{sub 2}S decomposition. Reaction rates and energy efficiency per H{sub 2}S molecule increase with increasing flow rate, although overall H{sub 2}S conversion decreases at constant power input. Voltage and current waveform analysis is ongoing to determine the fundamental operating characteristics of the reactors. A metal infiltrated porous ceramic membrane was prepared using vanadium as the metal and an alumina tube. Experiments with this type of membrane are continuing, but the results thus far have been consistent with those obtained in previous project years: plasma driven permeation or superpermeability

  10. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-10-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. A pulsed corona discharge (PCD) reactor has been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. A nonthermal plasma cannot be produced in pure H{sub 2}S with our reactor geometry, even at discharge voltages of up to 30 kV, because of the high dielectric strength of pure H{sub 2}S ({approx}2.9 times higher than air). Therefore, H{sub 2}S was diluted in another gas with lower breakdown voltage (or dielectric strength). Breakdown voltages of H{sub 2}S in four balance gases (Ar, He, N{sub 2} and H{sub 2}) have been measured at different H{sub 2}S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H{sub 2}S and the balance gas. H{sub 2}S conversion and the reaction energy efficiency depend on the balance gas and H{sub 2}S inlet concentrations. With increasing H{sub 2}S concentrations, H{sub 2}S conversion initially increases, reaches a maximum, and then decreases. H{sub 2}S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gases, such as N{sub 2} and H{sub 2}. These observations can be explained by the proposed reaction mechanism of H{sub 2}S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H{sub 2}S into hydrogen and sulfur.

  11. NOVEL COMPOSITE HYDROGEN-PERMEABLE MEMBRANES FOR NON-THERMAL PLASMA REACTORS FOR THE DECOMPOSITION OF HYDROGEN SULFIDE

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Ji-Jun Zhang; Guibing Zhao; Robyn J. Alcanzare; Linna Wang; Ovid A. Plumb

    2004-07-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant. This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655 x 10{sup -6} m{sup 3}/s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C{sub 2} and C{sub 3} hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50%-60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a

  12. One-step solvothermal tailoring the compositions and phases of nickel cobalt sulfides on conducting oxide substrates as counter electrodes for efficient dye-sensitized solar cells

    Science.gov (United States)

    Huang, Niu; Li, Guowang; Huang, Hua; Sun, Panpan; Xiong, Tianli; Xia, Zhifen; Zheng, Fang; Xu, Jixing; Sun, Xiaohua

    2016-12-01

    Several nickel cobalt sulfide (Ni-Co-S) counter electrodes (CEs) are prepared, and the Ni-Co-S nanoparticles are in-situ grown on SnO2: F (FTO) transparent conductive glasses via a facile solvothermal process, in which thiourea is used as the sulfurizing reagent. The X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometer are employed to measure the microstructure and composition of the Ni-Co-S CEs. When a proper amount of thiourea is adopted, fine crystalline NiCo2S4 CE is obtained. When the amount of thiourea is small or large, (Ni,Co)4S3 or (Ni,Co)3S4 CE is acquired, respectively. Cyclic voltammetry, electrochemical impedance spectroscopy, Tafel polarization and open-circuit voltage decay (OCVD) measurements all demonstrate that the electrocatalytic activities and electrical conductivities of these Ni-Co-S CEs all approach or exceed those of Pt-pyrolysis CE. Their superior electrochemical performances are further confirmed by fabricating DSSCs with the Ni-Co-S CEs, they display similar or better photo-electric conversion efficiencies to/than the Pt-pyrolysis counterpart.

  13. Enhanced Lithium-Ion Storage Capability of a Bismuth Sulfide/Graphene Oxide/Poly(3,4-ethylenedioxythiophene) Composite.

    Science.gov (United States)

    Mukkabla, Radha; Deepa, Melepurath; Srivastava, Avanish Kumar

    2015-10-26

    A Bi2 S3 /graphene oxide (GO) composite enwrapped by a poly(3,4-ethylenedioxythiophene) (PEDOT) coating was prepared for the first time for use as an anode in Li-ion batteries. Pristine Bi2 S3 nanoflowers and composites of Bi2 S3 /GO and Bi2 S3 /GO/PEDOT were assembled into half cells with Li metal as the counter electrode, and initial discharge capacities of 833, 1020, and 1300 mAh g(-1) , respectively, were obtained. Composites of Bi2 S3 /GO/PEDOT and Bi2 S3 /GO showed superior cycling stability and better rate capability than pristine Bi2 S3 . GO provides highly conducting interconnections, which allow facile propagation of electrons during charge/discharge, and this improves the ion-uptake capability of the Bi2 S3 nanoflowers and also increases the rate capability. PEDOT furnishes a protective coating that prevents detachment of the material from the current collector during cycling, and it also imparts better cycling stability to the Bi2 S3 /GO/PEDOT composite.

  14. Deoxygenation alters bacterial diversity and community composition in the ocean's largest oxygen minimum zone.

    Science.gov (United States)

    Beman, J Michael; Carolan, Molly T

    2013-01-01

    Oceanic oxygen minimum zones (OMZs) have a central role in biogeochemical cycles and are expanding as a consequence of climate change, yet how deoxygenation will affect the microbial communities that control these cycles is unclear. Here we sample across dissolved oxygen gradients in the oceans' largest OMZ and show that bacterial richness displays a unimodal pattern with decreasing dissolved oxygen, reaching maximum values on the edge of the OMZ and decreasing within it. Rare groups on the OMZ margin are abundant at lower dissolved oxygen concentrations, including sulphur-cycling Chromatiales, for which 16S rRNA was amplified from extracted RNA. Microbial species distribution models accurately replicate community patterns based on multivariate environmental data, demonstrate likely changes in distributions and diversity in the eastern tropical North Pacific Ocean, and highlight the sensitivity of key bacterial groups to deoxygenation. Through these mechanisms, OMZ expansion may alter microbial composition, competition, diversity and function, all of which have implications for biogeochemical cycling in OMZs.

  15. MICROSTRUCTURAL STUDY OF Fe-Cr-Al/Al COMPOSITE COATINGS DURING OXIDATION AND SULFIDATION AT 900 ℃

    Institute of Scientific and Technical Information of China (English)

    Z.L. Zhang; D.Y. Li; X. Q. Dong

    2007-01-01

    The microstructure of a composite coating system, which was composed of an inner layer of Fe-Cr-Al and an outer layer of aluminum, was studied after it was respectively oxidized and sulfurdized at elevated temperatures. Apart from the Al2O3 scale formed on the surface, the microstructure of the composite coatings exposed at 900℃ in air for 4h was a three-layer structure. The first layer consisted of a solid solution of Cr and Fe in α aluminum and an intermetallic compound FeAl3, while the second layer was a single phase of the aluminide and the third layer still remained the same appearance as the original Fe-Cr-Al coating.The microstructural observation of the specimen tested at 850-900 ℃ at low oxygen pressure and high sulfur pressure for 576h revealed that the surface coatings of the specimen had transformed into a duplex structure containing an outer layer and a thicker aluminide layer beneath. X-ray diffraction results showed that the out layer was composed of Al2S3 and Al2O3 and that AlCrFe2 was the main phase composition of the aluminide layer, with a few of Al2S3 and Al2O3 accompanied.

  16. Pore-water isotopic compositions and unsaturated-zone flow, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Yang, In C.

    2001-04-29

    Isotopic compositions of core-water samples from boreholes USW SD-6 and USW WT-24 indicate that recent water has been introduced at depth. Tritium, carbon, oxygen, and deuterium isotopic compositions all support younger water at depth in the two boreholes. Peaks in tritium concentrations in pore-water samples, indicating younger water than the other samples, observed near the basal vitrophyre of the Topopah Spring Tuff and at the bottom of the CHF and the top of the PP in both boreholes SD-6 and WT-24. Larger {sup 14}C activities in two pore-water samples from WT-24 at the bottom of the CHF and the top of the PP indicate younger water than in other samples from WT-24. More positive {delta}{sup 18}O and {delta}D values indicate younger water in samples of pore water at the bottom of the CHF in boreholes SD-6 and WT-24. The isotopic compositions indicating younger water at depth in boreholes SD-6 and WT-24 occur at the basal vitrophyre zone of the Topopah Spring Tuff and the bottom of the CHF/upper part of the PP, probably from lateral preferential flow through connected fractures (fast-flow paths). The source of the young water at borehole WT-24 probably was recharge from The Prow to the north, which then flowed laterally southward through the highly fractured TSw. The source of the young water at borehole SD-6 probably was water flow from the Solitario Canyon fault to the west, which then flowed laterally through the TSw and CHF.

  17. A new estimate of the chondrule cooling rate deduced from an analysis of compositional zoning of relict olivine

    Energy Technology Data Exchange (ETDEWEB)

    Miura, H. [Graduate School of Natural Sciences, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8501 (Japan); Yamamoto, T., E-mail: miurah@nsc.nagoya-cu.ac.jp [Center for Planetary Science, Kobe University, 7-1-48, Minamimachi, Minatojima, Chuo-ku, Kobe 650-0047 (Japan)

    2014-03-01

    Compositional zoning in chondrule phenocrysts records the crystallization environments in the early solar nebula. We modeled the growth of olivine phenocrysts from a silicate melt and proposed a new fractional crystallization model that provides a relation between the zoning profile and the cooling rate. In our model, we took elemental partitioning at a growing solid-liquid interface and time-dependent solute diffusion in the liquid into consideration. We assumed a local equilibrium condition, namely, that the compositions at the interface are equal to the equilibrium ones at a given temperature. We carried out numerical simulations of the fractional crystallization in one-dimensional planar geometry. The simulations revealed that under a constant cooling rate the growth velocity increases exponentially with time and a linear zoning profile forms in the solid as a result. We derived analytic formulae of the zoning profile, which reproduced the numerical results for wide ranges of crystallization conditions. The formulae provide a useful tool to estimate the cooling rate from the compositional zoning. Applying the formulae to low-FeO relict olivine grains in type II porphyritic chondrules observed by Wasson and Rubin, we estimate the cooling rate to be ∼200-2000 K s{sup –1}, which is greater than that expected from furnace-based experiments by orders of magnitude. Appropriate solar nebula environments for such rapid cooling conditions are discussed.

  18. Nickel Sulfide/Graphene/Carbon Nanotube Composites as Electrode Material for the Supercapacitor Application in the Sea Flashing Signal System

    Institute of Scientific and Technical Information of China (English)

    Hailong Chen; Ji Li; Conglai Long; Tong Wei; Guoqing Ning; Jun Yan; Zhuangjun Fan

    2014-01-01

    This work presents NiS/graphene/carbon nanotube (NiS/GNS/CNT) composites as electrode material for the supercapacitor application in sea flashing signal systems. NiS nanosheets were closely anchored on the conductive GNS-CNT networks. As a result, the NiS/GNS/CNT electrode showed a high specific capacitance of 2 377 F·g-1 at 2 mV·s-1 and good cycling stability compared with the pure NiS (1 599 F·g-1 ). The enhanced electrochemical performances are attributed to the synergetic effect between the conductive carbon and the pseudo-capacitive NiS. The high performance supercapacitor may provide application in the sea flashing signal system.

  19. Gamma ray spectrometry for recognition of hydrothermal alteration zones related to a low sulfidation epithermal gold mineralization (eastern Pontides, NE Türkiye)

    Science.gov (United States)

    Maden, Nafiz; Akaryalı, Enver

    2015-11-01

    This study presents an interpretation of radiospectrometric and magnetic data of Arzular mineralization site, which is one of the best examples for epithermal gold deposits located in the southern zone of the Eastern Pontides (NE Türkiye). Potassium is generally the most useful pathfinder element for gold mineralization zones because of its high level in altered rock surrounding the deposits. Where gold is hosted within quartz veins, typically the vein is low in the radioelements, but the hydrothermally altered host rocks will usually have a distinct radioelement signature useful for exploration. In this study, magnetic, susceptibility and radiospectrometric survey data radiometric signatures associated with the host rocks favorable for the mineralization, enhancing techniques such as the ratio maps as well as potassium (%K), equivalent thorium (eTh ppm) and equivalent uranium (eU ppm) maps were utilized. Our analysis showed that the gold mineralization associated with the alteration is significantly related to increase in potassium, due to adularia, a low T K-feldspar, and decreases in uranium and thorium due to the hydrothermal alteration and magmatic intrusion processes during the regional tectonic activities.

  20. High temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites densified by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Saucedo-Acuna, R.A. [Instituto e Ingenieria y Tecnologia, Universidad Autonoma de Cd. Juarez, Av. Del Charro 450 Norte, Col. Partido Romero, C.P. 32310, Cd. Juarez, Chihuahua (Mexico); Monreal-Romero, H.; Martinez-Villafane, A. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Chacon-Nava, J.G. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico)], E-mail: jose.chacon@cimav.edu.mx; Arce-Colunga, U. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Universidad Autonoma de Tamaulipas, Matamoros 8 y 9 Col. Centro C.P. 87110, Cd. Victoria, Tamaulipas (Mexico); Gaona-Tiburcio, C. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); De la Torre, S.D. [Centro de Investigacion e Innovacion Tecnologica (CIITEC)-IPN, D.F. Mexico (Mexico)

    2007-12-15

    The high temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites prepared by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. These composite powders have a particular metal-ceramic interpenetrating network and excellent mechanical properties. Oxidation-sulfidation tests were carried out at 900 deg. C, in a 2.5%SO{sub 2} + 3.6%O{sub 2} + N{sub 2}(balance) atmosphere for 48 h. The results revealed the influence of the sintering conditions on the specimens corrosion resistance, i.e. the Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composite sintered at 1310 deg. C/4 min showed better corrosion resistance (lower weight gains) compared with those found for the 1440 deg. C/5 min conditions. For the former composite, a protective Cr{sub 2}O{sub 3} layer immediately forms upon heating, whereas for the later pest disintegration was noted. Thus, under the same sintering conditions the Nb-Al{sub 2}O{sub 3} composites showed the highest weight gains. The oxidation products were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy.

  1. SEDIMENT TOXICITY AND COMMUNITY COMPOSITION OF BENTHOS AND COLONIZED PERIPHYTON IN THE EVERGLADES - FLORIDA BAY TRANSITIONAL ZONE.

    Science.gov (United States)

    Lewis, Michael A., Larry R. Goodman, John M. Macauley and James C. Moore. 2004. Sediment Toxicity and Community Composition of Benthos and Colonized Periphyton in the Everglades-Florida Bay Transitional Zone. Ecotoxicology. 13(3):231-244. (ERL,GB 1164). This survey provid...

  2. Fungicide leaching from golf greens: effects of root zone composition and surfactant use.

    Science.gov (United States)

    Larsbo, Mats; Aamlid, Trygve S; Persson, Lave; Jarvis, Nick

    2008-01-01

    Soil water repellency in golf putting greens may induce preferential "finger flow," leading to enhanced leaching of surface applied fungicides. We examined the effects of root zone composition, treatment with a non-ionic surfactant, and the use of the fungicide iprodion or a combination of azoxystrobin and propiconazole on soil water repellency, soil water content distributions, fungicide leaching, and turf quality during 1 yr. Soil water repellency was measured using the water drop penetration time (WDPT) test and tension infiltrometers. Our study was made on a 3-yr-old experimental green seeded with creeping bentgrass (Agrostis stolonifera L.) 'Penn A-4' at Landvik in southeast Norway. The facility consists of 16 lysimeters with two different root zone materials: (i) straight sand (1% gravel, 96% sand, 3% silt and clay, 4 g kg(-1) organic matter) (SS) and (ii) straight sand mixed with garden compost to an organic matter content of 21 g kg(-1) (Green Mix [GM]). Surfactant treatment resulted in 96% lower average WDPTs at 1 cm depth, three times higher water infiltration rates at the soil surface, and reduced spatial variation in soil water contents. Fungicide leaching was close to zero for the GM lysimeters probably due to stronger sorption. Concentrations in the drainage water from SS lysimeters often exceeded surface water guideline values for all three fungicides, but surfactant treatment dramatically reduced fungicide leaching from these lysimeters. In autumn and winter, surfactant-treated plots were more infected with fungal diseases probably because of higher water content in the turfgrass thatch layer.

  3. Mount St. Augustine volcano fumarole wall rock alteration: Mineralogy, zoning, composition and numerical models of its formation process

    Science.gov (United States)

    Getahun, A.; Reed, M.H.; Symonds, R.

    1996-01-01

    Intensely altered wall rock was collected from high-temperature (640??C) and low-temperature (375??C) vents at Augustine volcano in July 1989. The high-temperature altered rock exhibits distinct mineral zoning differentiated by color bands. In order of decreasing temperature, the color bands and their mineral assemblages are: (a) white to grey (tridymite-anhydrite); (b) pink to red (tridymite-hematite-Fe hydroxide-molysite (FeCl3) with minor amounts of anhydrite and halite); and (c) dark green to green (anhydrite-halite-sylvite-tridymite with minor amounts of molysite, soda and potash alum, and other sodium and potassium sulfates). The alteration products around the low-temperature vents are dominantly cristobalite and amorphous silica with minor potash and soda alum, aphthitalite, alunogen and anhydrite. Compared to fresh 1986 Augustine lava, the altered rocks exhibit enrichments in silica, base metals, halogens and sulfur and show very strong depletions in Al in all alteration zones and in iron, alkali and alkaline earth elements in some of the alteration zones. To help understand the origins of the mineral assemblages in altered Augustine rocks, we applied the thermochemical modeling program, GASWORKS, in calculations of: (a) reaction of the 1987 and 1989 gases with wall rock at 640 and 375??C; (b) cooling of the 1987 gas from 870 to 100??C with and without mineral fractionation; (c) cooling of the 1989 gas from 757 to 100??C with and without mineral fractionation; and (d) mixing of the 1987 and 1989 gases with air. The 640??C gas-rock reaction produces an assemblage consisting of silicates (tridymite, albite, diopside, sanidine and andalusite), oxides (magnetite and hercynite) and sulfides (bornite, chalcocite, molybdenite and sphalerite). The 375??C gas-rock reaction produces dominantly silicates (quartz, albite, andalusite, microcline, cordierite, anorthite and tremolite) and subordinate amounts of sulfides (pyrite, chalcocite and wurtzite), oxides (magnetite

  4. Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

    Science.gov (United States)

    Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

    2017-03-01

    Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data ( 600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥ 0.3 apfu F) with 0.2-2.7 wt.% SrO, 0-4.5 wt.% LREE2O3, 0-0.8 wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000 ppm Mn, 2300 ppm Fe, 200 ppm Ba, 150 ppm Pb, 700 ppm Th and 150 ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2 - and (VO4)3 - anions, substituting for (PO4)3 -, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2 wt.% SiO2, 1.5 wt.% SO3 and 660 ppm V). Although (CO3)2 - groups are very likely present in some samples, Raman micro

  5. Weathering of the New Albany Shale, Kentucky, USA: I. Weathering zones defined by mineralogy and major-element composition

    Science.gov (United States)

    Tuttle, M.L.W.; Breit, G.N.

    2009-01-01

    Comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks. Here minerals that release and fix major elements during progressive weathering of a bed of Devonian New Albany Shale in eastern Kentucky are documented. Samples were collected from unweathered core (parent shale) and across an outcrop excavated into a hillside 40 year prior to sampling. Quantitative X-ray diffraction mineralogical data record progressive shale alteration across the outcrop. Mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange. Altered primary minerals include K-feldspars, plagioclase, calcite, pyrite, and chlorite. Secondary minerals include jarosite, gypsum, goethite, amorphous Fe(III) oxides and Fe(II)-Al sulfate salt (efflorescence). The mineralogy in weathered shale defines four weathered intervals on the outcrop-Zones A-C and soil. Alteration of the weakly weathered shale (Zone A) is attributed to the 40-a exposure of the shale. In this zone, pyrite oxidization produces acid that dissolves calcite and attacks chlorite, forming gypsum, jarosite, and minor efflorescent salt. The pre-excavation, active weathering front (Zone B) is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability. Acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt, jarosite and minor goethite. Intensely weathered shale (Zone C) is depleted in feldspars, chlorite, gypsum, jarosite and efflorescent salts, but has retained much of its primary quartz, illite and illite-smectite. Goethite and amorphous FE(III) oxides increase due to hydrolysis of jarosite. Enhanced permeability in this zone is due to a 14% loss of the original mass in parent shale. Denudation rates suggest that characteristics of Zone C

  6. Secondary melting events in Semarkona chondrules revealed by compositional zoning in low-Ca pyroxene

    Science.gov (United States)

    Baecker, Bastian; Rubin, Alan E.; Wasson, John T.

    2017-08-01

    It is well established that many chondrules contain relict grains formed in previous generations of chondrules. We here describe evidence that chondrules experienced multiple mesostasis melting events while remaining closed systems. Spheroidal chondrule shapes resulted from surface-tension effects following a primary heating event that caused substantial melting (≳40%) of the precursor assemblages. In some high-FeO chondrules in LL3.00 Semarkona, low-Ca pyroxene phenocrysts show multiple overgrowth layers produced by secondary melting events. We characterized these layers with the electron microprobe in terms of Fe, Ca and Cr in two Semarkona chondrules. The first low-Ca pyroxene overgrowth that forms after a minor heating/melting event has low Ca and Fe; concentrations of these incompatibles gradually increase over the next 8 ± 4 μm until falling temperatures and slowing diffusion caused growth to stop. The next melting event remelts and mixes the local mesostasis; cooling causes growth of a normal igneously zoned layer. In the simplest cases, the Ca concentrations at the minima gradually increase towards the edge of the phenocryst. Heat deposition during heating events varied over a wide range; the weakest events produced recognizable changes in slopes (that we call "inflections" rather than minima). Large fractions of the individual phenocrysts were formed by the process that produced the overgrowth layers. It appears that overgrowth formation stopped when the Ca content of the mesostasis became high enough to make high-Ca pyroxene a liquidus phase. Both Semarkona chondrules include olivine phenocrysts similar in size and modal abundance to the low-Ca pyroxene phenocrysts. Olivine compositional profiles show symmetrical, apparently normal zoning except for asymmetries attributable to the presence of relict grains. Surface compositions of different olivine phenocrysts in the same chondrule are very similar to one another, consistent with growth from

  7. Thermomechanical cohesive zone models for analysis of composites failure under thermal gradients and transients

    Science.gov (United States)

    Hattiangadi, Ashwin A.

    A numerical framework to study multi-physics problem involving coupled thermomechanical analyses for cracks is outlined. Using a thermomechanical cohesive zone model (TM-CZM), load transfer behavior is coupled to heat conduction across a crack. Non-linear effects due to coupling between the mechanical and thermal problem occur through the conductance-separation response between crack faces as well as through the temperature dependence of material constants of the CZM. The TM-CZM is implemented in a convenient framework within the finite element method and applied in the study of: (i) interface crack growth; (ii) crack bridging; and (iii) photo-thermal imaging. Interface fracture in a thermal protection system (TPS) under transient monotonic and cyclic thermal loading is studied using the new TM-CZM and an analytical model. TPS includes an oxidation protection coating (OPC) on a carbon-carbon (C-C) composite substrate. The description of the load transfer behavior uses a traction-separation law with an internal residual property variable that determines the extent of damage caused by mechanical separation. Temperature dependence is incorporated, such that the interfacial strength and therefore the tractions decrease with temperature. The description of thermal transport includes an accurate representation of breakdown of interface conductance with increase in separation. The current state of interface failure, the presence of gas entrapped in the crack as well as radiative heat transfer determines the crack conductance. Coupling between thermal-mechanical analyses affects the interface crack initiation and growth behavior. An analytical model is presented for the uncoupled thermal-mechanical problem to calculate temperature fields and energy release rates. The TM-CZM is also applied in the study of bridged delamination cracks in composite laminates loaded under a temperature gradient. A micromechanism based bridging law is used for load transfer coupled to heat

  8. The source of phosphate in the oxidation zone of ore deposits: Evidence from oxygen isotope compositions of pyromorphite

    Science.gov (United States)

    Burmann, Fabian; Keim, Maximilian F.; Oelmann, Yvonne; Teiber, Holger; Marks, Michael A. W.; Markl, Gregor

    2013-12-01

    Pyromorphite (Pb5[PO4]3Cl) is an abundant mineral in oxidized zones of lead-bearing ore deposits and due to its very low solubility product effectively binds Pb during supergene alteration of galena (PbS). The capacity of a soil or near-surface fluid to immobilize dissolved Pb depends critically on the availability of phosphate in this soil or fluid. Potential phosphorus sources in soil include (i) release during biological processes, i.e. leaching from litter/lysis of microbial cells (after intracellular enzyme activity) in soil and hydrolysis from soil organic matter by extracellular enzymes and (ii) inorganic phosphate from the dissolution of apatite in the adjacent basement rocks. Intracellular enzyme activity in plants/microorganisms associated with kinetic fractionation produces an oxygen isotope composition distinctly different from inorganic processes in soil. This study presents the first oxygen isotope data for phosphate (δ18OP) in pyromorphite and a comprehensive data set for apatite from crystalline rocks. We investigated 38 pyromorphites from 26 localities in the Schwarzwald (Southwest Germany) and five samples from localities outside the Schwarzwald in addition to 12 apatite separates from gneissic and granitic host rocks. Pyromorphites had δ18OP values between +10‰ and +19‰, comparable to literature data on δ18OP in the readily available P fraction in soil (resin-extractable P) from which minerals potentially precipitate in soils. δ18OP values below the range of equilibrium isotope fractionation can be attributed either to apatites that formed geochemically (δ18OP of apatites:+6‰ to +9‰) or less likely to biological processes (extracellular enzyme activity). However, for most of our samples isotopic equilibrium with ambient water was indicated, which suggests biological activity. Therefore, we conclude that the majority of pyromorphites in oxidized zones of ore bodies formed from biologically cycled phosphate. This study highlights that

  9. Analysis of the Mineral Composition of the Human Calcified Cartilage Zone

    Directory of Open Access Journals (Sweden)

    Ying Zhang, Fuyou Wang, Hongbo Tan, Guangxing Chen, Lin Guo, Liu Yang

    2012-01-01

    Full Text Available As the connecting tissue between the hyaline articular cartilage and the subchondral bone, calcified cartilage zone (CCZ plays a great role in the force transmission and materials diffusion. However, the questions that remain to be resolved are its mineral composition and organization. In this study, 40 healthy human knee specimens were harvested; first the CCZ was dissected and observed by Safranin O/fast green staining, then CCZ chemical characteristics were measured by using amino acid assay and X-ray diffraction. The percentage of dry weight of type II collagen as an organic compound of CCZ was 20.16% ± 0.96%, lower than that of the hyaline cartilage layer (61.39% ± 0.38%; the percentage of dry weight of hydroxyapatite as an inorganic compound was 65.09% ± 2.31%, less than that of subchondral bone (85.78% ± 3.42%. Our study provides the accurate data for the reconstruction of the CCZ in vitro and the elucidation of CCZ structure and function.

  10. Capillary Zone Electrophoresis with Amperometric Detection for Composition Analysis of Laminarin

    Institute of Scientific and Technical Information of China (English)

    王清江; 丁飞; 李辉; 何品刚; 方禹之

    2003-01-01

    The composition of laminartn was firstly determined by analyz-ing its hydrolysis monosaccharides with capillary zone elec.lected opamum conditions, fucose, galactose, glucose, man-nose and xylose, which are hydrolysis products of iaminarin,could be perfectly separated within 20 min and showed signifi-cant current responses at copper electrodes. The linear ranges of fucose, galactose and glucose were from 1.0 × 10-6 to 2.0 ×10-4 mol·L-1, those of mannose and xylose were from 1.0×10-6 to 2.0× 10-4 mol·L-1, and their detect/on limits were at 10-7mol·L-1 level (S/N =3). The molar ratio of fucose,galactose,glucose,mannose and xylose in laminartn was 10.5:2.8:1.0:7.3:3.4 and the purity of this polysaccharide leached by the introduced leaching method was 95.7%. Compared to usual UV-vis and other spectrometric methods, analyzing polysaccharide by this method has some merit sof quickness,low-volume sampling,simple instrumentation,high sensitivity and high reproducibility.

  11. Constraints from fluid inclusions in mantle minerals on the composition of subduction-zone fluids

    Science.gov (United States)

    Schiano, P.; Provost, A.; Cluzel, N.

    2013-12-01

    -carbonates. Step-heating experiments were performed using a heating stage placed under the Raman microscope to estimate the initial composition of the trapped fluid. At 930°C, the final homogenization temperature of the associated melt inclusions, the fluid inclusions are homogeneous and composed of H2O, H2S and CO2. Salinities in the H2O-NaCl system calculated using freezing point depression relationship indicate that total salt of less than 10 wt% NaCl-equivalent is dissolved in the aqueous fluids. Trace-element data for Cl-bearing H2O-rich fluid inclusions are obtained using LA-ICPMS at Clermont-Ferrand. Comparison with compositions of the associated silicate melt inclusions allows determination of fluid/melt partition coefficients Dfluid/melt for the slab-released phases. The resultant coefficients are compared with experimentally determined Dfluid/melt, discussed in terms of recycling rates of key elements in subduction zones, and considered for the generation of trace element patterns typical for calc-alkaline magmas. [1] Schiano et al. (1995) Nature 377, 595-600 ; [2] Eiler et al. (2007) G3 8(9) doi :10.1029/2006GC001503

  12. 30 CFR 250.490 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... been confirmed. Well-control fluid means drilling mud and completion or workover fluid as appropriate... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Drilling Operations Hydrogen Sulfide § 250.490 Hydrogen... section when conducting drilling, well-completion/well-workover, and production operations in zones...

  13. Microbial community compositions in different functional zones of Carrousel oxidation ditch system for domestic wastewater treatment

    National Research Council Canada - National Science Library

    Xu, Dong; Liu, Sitong; Chen, Qian; Ni, Jinren

    2017-01-01

    The microbial community diversity in anaerobic-, anoxic- and oxic-biological zones of a conventional Carrousel oxidation ditch system for domestic wastewater treatment was systematically investigated...

  14. Evaluation of capillary zone electrophoresis for the determination of protein composition in therapeutic immunoglobulins and human albumins.

    Science.gov (United States)

    Christians, Stefan; van Treel, Nadine Denise; Bieniara, Gabriele; Eulig-Wien, Annika; Hanschmann, Kay-Martin; Giess, Siegfried

    2016-07-01

    Capillary zone electrophoresis (CZE) provides an alternative means of separating native proteins on the basis of their inherent electrophoretic mobilities. The major advantage of CZE is the quantification by UV detection, circumventing the drawbacks of staining and densitometry in the case of gel electrophoresis methods. The data of this validation study showed that CZE is a reliable assay for the determination of protein composition in therapeutic preparations of human albumin and human polyclonal immunoglobulins. Data obtained by CZE are in line with "historical" data obtained by the compendial method, provided that peak integration is performed without time correction. The focus here was to establish a rapid and reliable test to substitute the current gel based zone electrophoresis techniques for the control of protein composition of human immunoglobulins or albumins in the European Pharmacopoeia. We believe that the more advanced and modern CZE method described here is a very good alternative to the procedures currently described in the relevant monographs.

  15. EVALUATION OF MEDICINAL PLANT VALERIAN (VALERIANA OFFICINALIS L. ESSENTIAL OIL COMPOSITIONS CULTIVATED AT GARMSAR ZONE IN IRAN

    Directory of Open Access Journals (Sweden)

    Elham Morteza

    2012-06-01

    Full Text Available This study was conducted on experimental field at Garmsar zone in Iran during 2010 – 2011 in order to Evaluation of medicinal plant valerian (Valeriana officinalis L. essential oil compositions cultivated at Garmsar zone in Iran. Sowing date was 20 September and planting densitiy was 80000 plant ha–1. The volatile constituents of the root part of cultivated Valeriana officinalis were isolated by steam distillation and analysed by GC and GC-MS systems that were identified the 69 compositions. The results showed that oil percentage was 1.65%. The basic oil components among the identified 69 compounds were α-Fenchene (6.1%, Camphene (11%, Borneol (6.6%, Bornyl acetate (10.1% and Valerenal (12.9%. and Our finding may give applicable advice to commercial and medicinal and aromatic plants researches for management for increase of quantity and quality yields in medicinal and aromatic plants farming.

  16. Influence of diagenesis on the stable isotopic composition of biogenic carbonates from the Gulf of Tehuantepec oxygen minimum zone

    OpenAIRE

    Blanchet, Cécile; Kasten, S.; Vidal, Laurence; Poulton, S.W.; Ganeshram, R.; Thouveny, Nicolas

    2012-01-01

    International audience; In order to evaluate the influence of diagenetic and post-sampling processes on the stable oxygen and carbon isotope compositions of biogenic carbonates, we conducted a multiproxy study of organic-rich sediments from the eastern Pacific oxygen minimum zone. Core MD02-2520, which was retrieved from the Gulf of Tehuantepec (Mexico), has seasonal laminations and covers the last 40 kyr. Together with the presence of gypsum crystals and inorganic calcite aggregates, the occ...

  17. Diet composition of common leopards in Bardia National Park and the adjacent buffer zones and habitat corridor in Nepal

    OpenAIRE

    Deo, Rima

    2014-01-01

    The common Leopard (Panthera pardus) is the most widely distributed species among the large felids. It is a great challenge to manage their depredation on livestock at global level. In this study, I examined spatiotemporal patterns of leopard diet composition in Bardia National Park, Nepal, the buffer zones surrounding the park and a recently established habitat corridor that extends towards a protected area in India. Based on analyses of leopard scat contents, I investigated how the proporti...

  18. Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

    Science.gov (United States)

    Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.

    2004-01-01

    The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water-column sulfate to form barite, and metals combined with H2S derived from bacterial sulfate reduction to form sulfides. Higher temperatures and salinities and relatively oxidized ore-stage fluids (stages 2 and 3) compared with stage 1 were probably important controls on the abundances and relative amounts of metals in the fluids and the resulting sulfide chemistry. Textural observations and isotopic data show that preexisting barite was reductively dissolved, providing a source of H2S for sulfide mineral formation. In stage 3, the continued flow of hydrothermal fluids caused thermal

  19. The chemical composition and source identification of soil dissolved organic matter in riparian buffer zones from Chongming Island, China.

    Science.gov (United States)

    Wang, Yulai; Yang, Changming; Li, Jianhua; Shen, Shuo

    2014-09-01

    Dissolved organic matter (DOM) that is derived from the soil of riparian buffer zones has a complex chemical composition, and it plays an important role in the transport and transformation of pollutants. To identify the source of DOM and to better understand its chemical and structural properties, we collected 33 soil samples from zones with fluctuating water levels along the major rivers on Chongming Island, evaluated the DOM contents in riparian soil, analyzed the chemical composition and functional groups and traced DOM origins by using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) combined with clustering analysis. All sampling sites were divided into four groups by principal component analysis (PCA) on the basis of the DOM molecules. The results showed that there was no significant difference in the DOM contents between every two groups; however, the DOM fractions differed significantly among the different site groups in the following order: Σ lipids and Σ proteins>Σ sugars and Σ fatty acids>Σ amino acids, Σ indoles and Σ alkaloids. DOM in the riparian buffer zones originated from riparian plants, domestic sewage and agricultural activities, and the hydrophobic and amphiphilic fractions accounting for over 60% of the identified molecules were the dominant fractions. Our study has confirmed the heterogeneous properties of DOM, and it is of vital importance to isolate and characterize the various DOM fractions at the molecular level for a better understanding of the behavior and roles of DOM in the natural environment.

  20. [Change in the composition and structure of the metal in the zone of the welded seam of dental drill blanks].

    Science.gov (United States)

    Altareva, G I; Bazhukhin, V I; Gerasev, G P; Matukhnov, V M; Shmyreva, T P

    1982-01-01

    Composition and structure of metals in the meld zone connecting a dental burr handpiece made of hard alloy BK-6 with a shank made of steel 20X13 are examined by the X-ary microanalyzer MS-46 and the X-ray diffractometer "dPOH-2". Representative interdiffusion processes of alloy components into steel and, converserly, iron from steel into hard alloy are found. After melding, the transition layer has been shown to represent the cobalt-iron solid solution with variable concentration of the components through the layer, tungsten carbid particles being uniformly spread all over the metallic matrix. The phasic composition change is analysed in the course of material welding. The enrichment of stell melt with carbon of tungsten carbid results in the formation of gamma-Fe phase in the meld zone. The failure of burr blanks is noted to occur at the interface of the second (10-20 micrometer) and the first (130-140 micrometer) zones. The increase in the concentration of both iron and iron-containing phases--alpha-Fe, gamma-Fe, Fe3W3C--at the surface of steel fracture is responsible for the failures.

  1. Sulfide Mineralogy and Geochemistry

    Science.gov (United States)

    Dilles, John

    2007-02-01

    Reviews in Mineralogy and Geochemistry Series, Volume 61 David J. Vaughan, Editor Geochemical Society and Mineralogical Society of America; ISBN 0-939950-73-1 xiii + 714 pp.; 2006; $40. Sulfide minerals as a class represent important minor rock-forming minerals, but they are generally known as the chief sources of many economic metallic ores. In the past two decades, sulfide research has been extended to include important roles in environmental geology of sulfide weathering and resultant acid mine drainage, as well as in geomicrobiology in which bacteria make use of sulfides for metabolic energy sources. In the latter respect, sulfides played an important role in early evolution of life on Earth and in geochemical cycling of elements in the Earth's crust and hydrosphere.

  2. Genetic Pd, Pt, Au, Ag, and Rh mineralogy in Noril'sk sulfide ores

    Science.gov (United States)

    Spiridonov, E. M.; Kulagov, E. A.; Serova, A. A.; Kulikova, I. M.; Korotaeva, N. N.; Sereda, E. V.; Tushentsova, I. N.; Belyakov, S. N.; Zhukov, N. N.

    2015-09-01

    The undeformed ore-bearing intrusions of the Noril'sk ore field (NOF) cut through volcanic rocks of the Late Permian-Early Triassic trap association folded in brachysynclines. Due to the nonuniform load on the roof of intrusive bodies, most sulfide melts were squeezed, up to the tops of ore-bearing intrusions; readily fusible Ni-Fe-Cu sulfide melts were almost completely squeezed. In our opinion, not only one but two stages of mineralization developed at the Noril'sk deposits: (i) syntrap magmatic and (ii) epigenetic post-trap metamorphic-hydrothermal. All platinum-group minerals (PGM) and minerals of gold are metasomatic in the Noril'sk ores. They replaced sulfide solid solutions and exsolution structures. All types of PGM and Au minerals occur in the ores, varying in composition from pyrrhotite to chalcopyrite, talnakhite, mooihoekite, and rich in galena; they are localized in the inner and outer contact zones and differ only in the quantitative proportions of ore minerals. The aureoles of PGM and Au-Ag minerals are wider than the contours of sulfide bodies and coincide with halos of fluid impact on orebodies and adjacent host rocks. The pneumatolytic PGM and Au-Ag minerals are correlated in abundance with the dimensions of sulfide bodies. Their amounts are maximal in veins of late fusible ore composed of eutectic PbS ss and iss intergrowths, as well as at their contacts. The Pd and Pt contents in eutectic sulfide ores of NOF are the world's highest. In the process of noble-metal mineral formation, the fluids supply Pd, Pt, Au, As, Sb, Sn, Bi, and a part of Te, whereas Fe, Ni, Cu, Pb, Ag, Rh, a part of Te and Pd are leached from the replaced sulfide minerals. The pneumatolytic PGM of the early stage comprises Pd and Pt intermetallic compounds enriched in Au along with Pd-Pt-Fe-Ni-Cu-Sn-Pb(As) and (Pd,Pt,Au)(Sn,Sb,Bi,Te,As) solid solutions. Pneumatolytic PGM and Au minerals of the middle stage are products of solid-phase transformation and recrystallization of

  3. Reflectance spectroscopy of natural organic solids, iron sulfides and their mixtures as refractory analogues for Rosetta/VIRTIS' surface composition analysis of 67P/CG

    Science.gov (United States)

    Moroz, Lyuba V.; Markus, Kathrin; Arnold, Gabriele; Henckel, Daniela; Kappel, David; Schade, Ulrich; Rousseau, Batiste; Quirico, Eric; Schmitt, Bernard; Capaccioni, Fabrizio; Bockelee-Morvan, Dominique; Filacchione, Gianrico; Érard, Stéphane; Leyrat, Cedric; VIRTIS Team

    2016-10-01

    Analysis of 0.25-5 µm reflectance spectra provided by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) onboard Rosetta orbiter revealed that the surface of 67P/CG is dark from the near-UV to the IR and is enriched in refractory phases such as organic and opaque components. The broadness and complexity of the ubiquitous absorption feature around 3.2 µm suggest a variety of cometary organic constituents. For example, complex hydrocarbons (aliphatic and polycyclic aromatic) can contribute to the feature between 3.3 and 3.5 µm and to the low reflectance of the surface in the visible. Here we present the 0.25-5 µm reflectance spectra of well-characterized terrestrial hydrocarbon materials (solid oil bitumens, coals) and discuss their relevance as spectral analogues for a hydrocarbon part of 67P/CG's complex organics. However, the expected low degree of thermal processing of cometary hydrocarbons (high (H+O+N+S)/C ratios and low carbon aromaticities) suggests high IR reflectance, intense 3.3-3.5 µm absorption bands and steep red IR slopes that are not observed in the VIRTIS spectra. Fine-grained opaque refractory phases (e.g., iron sulfides, Fe-Ni alloys) intimately mixed with other surface components are likely responsible for the low IR reflectance and low intensities of absorption bands in the VIRTIS spectra of the 67P/CG surface. In particular, iron sulfides are common constituents of cometary dust, "cometary" chondritic IDPs, and efficient darkening agents in primitive carbonaceous chondrites. Their effect on reflectance spectra of an intimate mixture is strongly affected by grain size. We report and discuss the 0.25-5 µm reflectance spectra of iron sulfides (meteoritic troilite and several terrestrial pyrrhotites) ground and sieved to various particle sizes. In addition, we present reflectance spectra of several intimate mixtures of powdered iron sulfides and solid oil bitumens. Based on the reported laboratory data, we discuss the ability of

  4. Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

    Institute of Scientific and Technical Information of China (English)

    FAN Qicheng; ZHANG Hongfu; SUI Jianli; ZHAI Mingguo; SUN Qian; LI Ni

    2005-01-01

    On the basis of mineral assemblage, mineralogy, petrology, and major, trace elemental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work constrained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumulates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly composed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean terrain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

  5. Analysis of a high intensity shear zone between overlapping fiber ends in a polymer matrix composite

    DEFF Research Database (Denmark)

    Lindgreen, Britta

    2008-01-01

    The formation of high intensity shear zones in a glass fiber reinforced thermoplast is studied numerically. The thermoplast is characterized by a finite strain elastic-viscoplastic constitutive relation and the calculations are carried out using a dynamic finite element program where plane strain...... conditions are assumed to prevail in the direction of the thickness. Different ratios of the elongation strain and the transverse strain are studied to consider the effect of different levels of stress triaxiality and the effect of these states on the shear zone development and emerging strain and stress...

  6. Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

    Science.gov (United States)

    Joslin, Steven M.

    1995-01-01

    A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

  7. Estimation of percolating water dynamics through the vadose zone of the Postojna cave on the basis of isotope composition

    Directory of Open Access Journals (Sweden)

    Janja Kogovšek

    2007-12-01

    Full Text Available Within the scope of monitoring water percolation through the 100-m thick vadose zone in the area of Postojnska jama continuous measurements of precipitation were carried out on the surface, and continuous measurements of water flowandphysicalandchemicalparametersof selected water trickles were performed under the surface. Occasional samples of percolating waters were taken for the analysis of water oxygen isotope composition. An exponential model of groundwater flowwaselaborated,bymeansofwhichtheretentiontime of water in individual trickles was estimated. Modelled retention times of groundwater range from 2.5 months to over one year.

  8. Compositional and Oxidation State Zoning in Martian Pyroxene: Paradox or Process Indicator

    Science.gov (United States)

    Delaney, Jeremy S.; Dyar, M. D.

    2002-01-01

    Coordinated zoning studies of major, minor, trace elements and oxidation states in Martian minerals elucidate the magmatic evolution of QUE94201 and suggest an important role for olivine and volatile fluxing in a complex magmatic history. Additional information is contained in the original extended abstract.

  9. Modeling of Sulfide Microenvironments on Mars

    Science.gov (United States)

    Schwenzer, S. P.; Bridges, J. C.; McAdam, A.; Steer, E. D.; Conrad, P. G.; Kelley, S. P.; Wiens, R. C.; Mangold, N.; Grotzinger, J.; Eigenbrode, J. L.; Franz, H. B.; Sutter, B.

    2016-01-01

    Yellowknife Bay (YKB; sol 124-198) is the second site that the Mars Science Laboratory Rover Curiosity investigated in detail on its mission in Gale Crater. YKB represents lake bed sediments from an overall neutral pH, low salinity environment, with a mineralogical composition which includes Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral phyllosilicates. We investigate whether sulfide alteration could be associated with ancient habitable microenvironments in the Gale mudstones. Some textural evidence for such alteration may be pre-sent in the nodules present in the mudstone.

  10. Iron-sulfide crystals in probe deposits

    DEFF Research Database (Denmark)

    Laursen, Karin; Frandsen, Flemming

    1998-01-01

    Iron-sulfides were observed in deposits collected on a probe inserted at the top of the furnace of a coal-fired power station in Denmark. The chemical composition of the iron-sulfides is equivalent to pyrrhotite (FeS). The pyrrhotites are present as crystals and, based on the shape of the crystals......, it was deduced that they were not deposited but instead grew within the deposit. The presence of unburned char particles within the deposits supports the concept that a reducing environment existed in the deposits. Two processes are proposed for explaining the existence of pyrrhotite crystals within a deposit...

  11. Influence of technology of growing on yield and oil chemical composition of linseed in Non-chernozem zone of Russia

    Directory of Open Access Journals (Sweden)

    Vinogradov Dmitriy V.

    2012-01-01

    Full Text Available The influence of the level of mineral nutrition and rate of seed sowing on yield and fatty acid composition of linseed (Linum usitatissimum L. in the Non-chernozem zone of Russia was studied. It was shown that the level of mineral fertilizers N - 90, P2O5 - 60, and K2O - 60 kg/ha under the rate of sowing of 8 million seeds/ha provided maximum seed yield of 1.94 t/ha. A clear correlation between oil content and rate of sowing has not been established. Under an increasing level of mineral nutrition, oil content was slightly increased. The composition of oil was slightly changed under the influence of the studied factors.

  12. Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

    Science.gov (United States)

    Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

    2016-10-01

    Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern

  13. Compositional evolution of the emplaced fuel source in the vadose zone field experiment at airbase Vaerlose, Denmark

    DEFF Research Database (Denmark)

    Broholm, Mette Martina; Christophersen, Mette; Maier, U.;

    2005-01-01

    A field experiment was performed in a sandy vadose zone, studying the fate of an emplaced fuel-NAPL source, composed of 13 hydrocarbons and a tracer. The UNIFAC model was used to test the nonideal behavior of the source, and the numerical model MIN3P was used for assessing the effect of biodegrad......A field experiment was performed in a sandy vadose zone, studying the fate of an emplaced fuel-NAPL source, composed of 13 hydrocarbons and a tracer. The UNIFAC model was used to test the nonideal behavior of the source, and the numerical model MIN3P was used for assessing the effect...... of biodegradation on source evolution. The diffusive loss to the surrounding vadose zone and the atmosphere created temporary gradients in mole fractions of the individual compounds within the source NAPL. The evolution of the source composition corresponded in general with expectations based on Raoult's Law....... Positive deviations were calculated for the aromatic compounds. The effect of biodegradation on source depletion, evaluated by numerical modeling, was greater for the aromatic as compared to the aliphatic compounds. Hence, the faster depletion of the aromatic relative to aliphatic compounds of similar...

  14. Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

    Science.gov (United States)

    Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

    2016-12-01

    Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

  15. Modelling of interfacial transition zone effect on resistance to crack propagation in fine-grained cement-based composites

    Directory of Open Access Journals (Sweden)

    H. Šimonová

    2017-07-01

    Full Text Available In this paper, the attention is paid to investigation of the importance of the interfacial transition zone (ITZ in selected fine-grained cement-based composites for the global fracture behaviour. This is a region of cement paste around the aggregate particles which specific features could have significant impact on the final behaviour of cement composites with a crack tip nearby this interface under applied tension. The aim of this work is to show the basic interface microstructure by scanning electron microscopy (SEM done by MIRA3 TESCAN and to analyse the behaviour of such composite by numerical modelling. Numerical studies assume two different ITZ thicknesses taken from SEM analysis. A simplified cracked geometry (consisting of three phases – matrix, ITZ, and aggregate is modelled by means of the finite element method with a crack terminating at the matrix–ITZ interface. ITZ’s modulus of elasticity is taken from generalized self-consistent scheme. A few conclusions are discussed based on comparison of the average values of the opening stress ahead of the crack tip with their critical values. The analyses dealing with the effect of ITZ’s properties on the stress distribution should contribute to better description of toughening mechanisms in silicate-based composites.

  16. The use of ERTS-1 images in the search for large sulfide deposits in the Chagai District, Pakistan

    Science.gov (United States)

    Schmidt, R. G. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Visual examination of color composites was tested under relatively ideal conditions for direct detection of large hydrothermal sulfide deposits at the low-grade porphyry copper deposit at Saindak, western Chagai District, Pakistan. The Saindak deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by a resistant rim of hornfels and propylitically altered rock. The geomorphic features related to the Saindak deposit are easily distinguished on ERTS-1 images. Attempts to detect a color anomaly using false-color composites were not successful. About 36,000 square km of the western Chagai District were examined on false-color composites for direct evidence of large sulfide deposits. New geologic information acquired from the images was used in conjunction with the known geology to evaluate two previously known proposed areas and to suggest seven additional targets for field checking, one of which is proposed on the basis of tonal anomaly alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District; and also that a rim like that at Saindak does not form if regional metamorphism has increased the resistance of the country rock to erosion.

  17. Interstellar hydrogen sulfide.

    Science.gov (United States)

    Thaddeus, P.; Kutner, M. L.; Penzias, A. A.; Wilson, R. W.; Jefferts, K. B.

    1972-01-01

    Hydrogen sulfide has been detected in seven Galactic sources by observation of a single line corresponding to the rotational transition from the 1(sub 10) to the 1(sub 01) levels at 168.7 GHz. The observations show that hydrogen sulfide is only a moderately common interstellar molecule comparable in abundance to H2CO and CS, but somewhat less abundant than HCN and much less abundant than CO.

  18. Sulfide and methane production in sewer sediments.

    Science.gov (United States)

    Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

    2015-03-01

    Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

  19. Sulfide Oxidation in the Anoxic Black-Sea Chemocline

    DEFF Research Database (Denmark)

    JØRGENSEN, BB; FOSSING, H.; WIRSEN, CO

    1991-01-01

    -99 m. Oxygen in the water column immediately overlying the sulfide zone was depleted to undetectable levels resulting in a 20-30-m deep intermediate layer of O2- and H2S-free water. Radiotracer studies with S-35-labelled H2S showed that high rates of sulfide oxidation, up to a few micromoles per liter...... per day, occurred in anoxic water at the top of the sulfide zone concurrent with the highest rates of dark CO2 assimilation. The main soluble oxidized products of sulfide were thiosulfate (68-82%) and sulfate. Indirect evidence was presented for the formation of elemental sulfur which accumulated...... that the measured H2S oxidation rates were 4-fold higher than could be explained by the downward flux of organic carbon and too high to balance the availability of electron acceptors such as oxidized iron or manganese. A nitrate maximum at the lower boundary of the O2 zone did not extend down to the sulfide zone....

  20. Cerro de Pasco and other massive sulfide deposits of central Peru

    Energy Technology Data Exchange (ETDEWEB)

    Cheney, E.S.

    1985-01-01

    The famous Cerro de Pasco Pb-Zn-Ag deposit historically has been considered to be hydrothermally derived from an adjacent Tertiary volcanic vent. However, texturally massive pyrite-chert and pyrite-sphalerite-galena in the deposit have the same strike and cross folds as the adjacent pre-Tertiary strata. Both the deposit and the strata are cut by one of the large Longitudinal Faults. Both dikes and pyrite-enargite veins associated with the vent cut the massive sulfides; fragments of massive pyrite occur in the vent. A few examples of laminated pyrite and chert, banded pyrite and chert, banded pyrite and sphalerite, and banded pyrite, sphalerite, and galena are preserved in the massive sulfide portion of the deposit. The deposit has the composition and zoning patterns typical of shale-hosted massive sulfides. Cerro de Pasco probably in part of the pelitic Devonian Excelsior formation. The Colquijirca deposit 8 km to the south and the San Cristobal district 110 km to the south likewise have been considered to be Tertiary volcanic hydrothermal deposits. Colquijirca consists of stratigraphically controlled mantos of layered pyrite, chert and tuff in the Tertiary Calera formation. The mantos of the San Cristobal district are along the upper contact of the pyritic, Permian, Catalina felsic volcanic rocks; some ore consists of laminated pyrite and sphalerite. Tertiary plutons are conspicuously absent at San Cristobal, and the ores are brecciated by Tertiary folding.

  1. The timing of compositionally-zoned magma reservoirs and mafic 'priming' weeks before the 1912 Novarupta-Katmai rhyolite eruption

    Science.gov (United States)

    Singer, Brad S.; Costa, Fidel; Herrin, Jason S.; Hildreth, Wes; Fierstein, Judy

    2016-10-01

    The June, 6, 1912 eruption of more than 13 km3 of dense rock equivalent (DRE) magma at Novarupta vent, Alaska was the largest of the 20th century. It ejected >7 km3 of rhyolite, ∼1.3 km3 of andesite and ∼4.6 km3 of dacite. Early ideas about the origin of pyroclastic flows and magmatic differentiation (e.g., compositional zonation of reservoirs) were shaped by this eruption. Despite being well studied, the timing of events that led to the chemically and mineralogically zoned magma reservoir remain poorly known. Here we provide new insights using the textures and chemical compositions of plagioclase and orthopyroxene crystals and by reevaluating previous U-Th isotope data. Compositional zoning of the magma reservoir likely developed a few thousand years before the eruption by several additions of mafic magma below an extant silicic reservoir. Melt compositions calculated from Sr contents in plagioclase fill the compositional gap between 68 and 76% SiO2 in whole pumice clasts, consistent with uninterrupted crystal growth from a continuum of liquids. Thus, our findings support a general model in which large volumes of crystal-poor rhyolite are related to intermediate magmas through gradual separation of melt from crystal-rich mush. The rhyolite is incubated by, but not mixed with, episodic recharge pulses of mafic magma that interact thermochemically with the mush and intermediate magmas. Hot, Mg-, Ca-, and Al-rich mafic magma intruded into, and mixed with, deeper parts of the reservoir (andesite and dacite) multiple times. Modeling the relaxation of the Fe-Mg concentrations in orthopyroxene and Mg in plagioclase rims indicates that the final recharge event occurred just weeks prior to the eruption. Rapid addition of mass, volatiles, and heat from the recharge magma, perhaps aided by partial melting of cumulate mush below the andesite and dacite, pressurized the reservoir and likely propelled a ∼10 km lateral dike that allowed the overlying rhyolite to reach the

  2. Composite Binary Sequences with a Large Ensemble and Zero Correlation Zone

    Directory of Open Access Journals (Sweden)

    S. S. Yudachev

    2015-01-01

    Full Text Available The article considers a proposed class of derived signals such as composite binary sequences for application in advanced spread spectrum radio systems of various purposes, using signals based on spectrum spreading by direct sequence method. Considered composite sequences, having a representative set of lengths and unique correlation properties, compares favorably with the widely used at present large ensembles formed on a single algorithmic basis. To evaluate the properties of the composite sequences generated on the basis of two components - the Barker code and Kerdock sequences, expressions of periodic and aperiodic correlation functions are given.An algorithm for generating practical ensembles of composite sequences is presented. On the basis of the algorithm and its software implementation in C #, the samples of the sequence ensembles of various lengths were obtained and their periodic and aperiodic correlation functions and statistical characteristics were studied in detail. As an illustration, some of the most typical correlation functions are presented. The most remarkable characteristics allowing a ssessing the feasibility of using this type of sequences in the design of specific types of radio systems are considered.On the basis of the proposed program and the performed calculations the conclusions can be drawn about the possibility of using the sequences of these classes, with the aim of reducing intra-system disturbance in the projected spread spectrum CDMA.

  3. Theoretical Investigation of Calculating Temperatures in the Combining Zone of Cu/Fe Composite Plate Jointed by Explosive Welding

    Science.gov (United States)

    Qu, Y. D.; Zhang, W. J.; Kong, X. Q.; Zhao, X.

    2016-03-01

    The heat-transfer behavior of the interface of Flyer plate (or Base Plate) has great influence on the microcosmic structures, stress distributions, and interface distortion of the welded interface of composite plates by explosive welding. In this paper, the temperature distributions in the combing zone are studied for the case of Cu/Fe composite plate jointed by explosive welding near the lower limit of explosive welding. The results show that Flyer plate (Cu plate) and Base Plate (Fe plate) firstly almost have the same melting rate in the explosive welding process. Then, the melting rate of Cu plate becomes higher than that of Fe plate. Finally, the melt thicknesses of Cu plate and Fe plate trend to be different constants, respectively. Meanwhile, the melting layer of Cu plate is thicker than that of Fe plate. The research could supply some theoretical foundations for calculating the temperature distribution and optimizing the explosive welding parameters of Cu/Fe composite plate to some extent.

  4. [XRD, FTIR and XPS analysis of oxidized particles from Dongshengmiao pyrite-polymetallic sulfide deposit, inner Mongolia].

    Science.gov (United States)

    Yuan, Xue-Ling; Cao, Jian-Jin; Xie, Fang-Yan; Yang, Xiao-Jie; Yan, Hong-Bin; Lai, Pei-Xin; Wang, Zheng-Hai; Zeng, Jian-Nian

    2013-01-01

    In the present paper, characteristics of material compositions, phase structures, surface element states, and transformation mechanism of oxidized particles from Dongshengmiao pyrite-polymetallic sulfide deposit were studied using modern analytical testing technology including XRD, FTIR and XPS. The results show that the samples consist of gypsum, calcite, quartz, muscovite, goethite, organic matter, etc. Primary ore in deep oxidation zone mainly under went such processes as oxidization, hydrolysis, dehydration and carbonation. Compared to the surface oxidation zone of arid and extremely arid regions in the northwestern China, the oxidation process and oxidizing condition of the deep oxidation zone were less complex. New mineral type was also not found, and extensively developed sulfate minerals were rare to be seen. The research results can not only be applied to mineral identification of oxidized particles from this type of ore deposit but also play an important role in ore exploration, mining, mineral processing, etc.

  5. Sulfur speciation and sulfide oxidation in the water column of the Black Sea

    Science.gov (United States)

    Luther, George W., III; Church, Thomas M.; Powell, David

    We have applied sulfur speciation techniques to understand the chemistry and cycling of sulfur in Black Sea waters. The only reduced dissolved inorganic sulfur species detected (above the low minimum detection limits of the voltammetric methods employed) in the water column was hydrogen sulfide. The maximum concentration of sulfide (423 μM) is similar to previous reports. Using a cathodic stripping square wave voltammetry (CSSWV) method for nanomolar levels of sulfide, we determined the precise boundary between the "free" hydrogen sulfide (sulfidic) zone and the upper (oxic/suboxic) water column at the two stations studied. This boundary has apparently moved up by about 50 m in the past 20 years. Our results help demonstrate three chemically distinct zones of water in the central basin of the Black Sea: (1) the oxic [0-65 m], (2) the anoxic/nonsulfidic [65-100 m] and (3) the sulfidic [>100 m]. Sulfide bound to metals ("complexed" sulfide) is observed in both the oxic and anoxic/nonsulfidic zones of the water column. This supports previous studies on metal sulfide forms. From the electrochemical data, it is possible to estimate the strength of the complexation of sulfide to metals (log K = 10 to 11). Thiosulfate and sulfite were below our minimum detectable limit (MDL) of 50 nM using CSSWV. Elemental sulfur (MDL 5 nM) was detected below the onset of the hydrogen sulfide zone (90-100 m) with a maximum of 30-60 nM near 120 m. The sulfur speciation results for the Black Sea are lower by one order of magnitude or more than other marine systems such as the Cariaco Trench and salt marshes. New HPLC techniques were applied to detect thiols at submicromolar levels. The presence of thiols (2-mercaptoethylamine, 2-mercaptoethanol, N-acetylcysteine and glutathione) is correlated with the remineralization of organic matter at the oxic and anoxic/nonsulfidic interface. Water samples collected from the upper 50 m of the sulfidic zone showed significant sulfide oxidation on

  6. Petrogenesis and ore genesis of the Permian Huangshanxi sulfide ore-bearing mafic-ultramafic intrusion in the Central Asian Orogenic Belt, western China

    Science.gov (United States)

    Mao, Ya-Jing; Qin, Ke-Zhang; Li, Chusi; Xue, Sheng-Chao; Ripley, Edward M.

    2014-07-01

    The Permian Huangshanxi mafic-ultramafic intrusion hosts one of the two largest magmatic sulfide deposits in the Eastern Tianshan which is situated in the southern margin of the Central Asian Orogenic Belt. In this paper we use mineral compositions and whole-rock geochemical data to decipher the genetic relationship between magma evolution and sulfide mineralization. The Huangshanxi intrusion consists of three separate intrusive units. Important sulfide mineralization occurs in the base of the last intrusive unit, an elongated, layered ultramafic body composed of lherzolite at the bottom, olivine websterite in the middle and websterite at the top. Based on olivine-liquid equilibria and mass balance, the MgO and FeO contents in the parental magma for a lherzolite sample are estimated to be 8.71 and 8.36 wt.%, respectively. The Huangshanxi mafic-ultramafic intrusive rocks and the estimated "trapped liquids" for several olivine-orthopyroxene cumulate rocks all show light rare earth element enrichments relative to heavy rare earth elements and significant Nb depletions relative to Th and La, which are similar to the characteristics of coeval basalts in the region. The arc-like geochemical features are attributed to pre-Permian mantle metasomatism by slab-derived fluids. Partial melting of the previously-modified mantle is thought to have resulted from heating by upwelling asthenosphere associated with post-subduction lithosphere delamination or by mantle plume activity. The relationship between the Fo and Ni contents of olivine crystals from the Huangshanxi sulfide-poor ultramafic rocks (source mantle. Stratigraphic reversals in olivine Fo contents and bulk sulfide PGE tenors suggest that multiple magma replenishments occurred during the development of the Huangshanxi magmatic Ni-Cu sulfide deposit. The sulfide ore formation can be divided into two stages: a conduit stage during which immiscible sulfide droplets and olivine crystals were brought up by ascending magma

  7. Study on Tribological Behavior of Fiber Reinforced Polyphenylene Sulfide Composites%纤维增强聚苯硫醚复合材料摩擦磨损性能的研究

    Institute of Scientific and Technical Information of China (English)

    牛军锋

    2012-01-01

    分别以玻璃纤维(GF)与碳纤维(CF)作为增强体制备了聚苯碳醚(PPS)纤维增强复合材料.研究了GF/PPS和CF/PPS复合材料的摩擦磨损性能,以及不同体积分数的纤维增强体、不同载荷与滑动速度对复合材料的摩擦磨损性能的影响.结果表明:GF与CF的引入有效地提高了复合材料的摩擦磨损性能;随纤维体积分数的增加复合材料的摩擦系数逐渐增加,随载荷的增加复合材料的摩擦系数逐渐降低,但磨损率增大.%Fiber reinforced polyphenylene sulfide(PPS)composites were prepared by means of adding glass fiber(GF)and carbon fiber(CF).The friction and wear properties of GF/PPS and CF/PPS composites were studied, in addition, the effects of fiber reinforcements with different volume fraction on the friction and wear properties of composites were researched, as well as the impacts of different load on friction and wear properties of composites.The results show that the GF and CF can effectively improve the friction and wear properties of composites, the friction coefficient decreases gradually with the increase of fiber volume fraction.Moreover, the friction coefficient also decreases with the increase of the load, but the wear rate increases.

  8. Microfluidic free-flow zone electrophoresis and isotachophoresis using carbon black nano-composite PDMS sidewall membranes.

    Science.gov (United States)

    Fu, Xiaotong; Mavrogiannis, Nicholas; Ibo, Markela; Crivellari, Francesca; Gagnon, Zachary R

    2017-01-01

    We present a new type of free-flow electrophoresis (FFE) device for performing on-chip microfluidic isotachophoresis and zone electrophoresis. FFE is performed using metal gallium electrodes, which are isolated from a main microfluidic flow channel using thin micron-scale polydimethylsiloxane/carbon black (PDMS/CB) composite membranes integrated directly into the sidewalls of the microfluidic channel. The thin membrane allows for field penetration and effective electrophoresis, but serves to prevent bubble generation at the electrodes from electrolysis. We experimentally demonstrate the ability to use this platform to perform on-chip free-flow electrophoretic separation and isotachophoretic concentration. Due to the small size and simple fabrication procedure, this PDMS/CB platform could be used as a part of an on-chip upstream sample preparation toolkit for portable microfluidic diagnostic applications.

  9. Composition and structure of aggregates from compacted soil horizons in the southern steppe zone of European Russia

    Science.gov (United States)

    Sorokin, A. S.; Abrosimov, K. N.; Lebedeva, M. P.; Kust, G. S.

    2016-03-01

    The composition and structure of aggregates from different agrogenic soils in the southern steppe zone of European Russia have been studied. It is shown that the multi-level study (from the macro- to microlevel) of these horizons makes it possible to identify soil compaction caused by different elementary soil processes: solonetz-forming, vertisol-forming, and mechanical (wheel) compaction in the rainfed and irrigated soils. The understanding of the genesis of the compaction of soil horizons (natural or anthropogenic) is important for the economic evaluation of soil degradation. It should enable us to make more exact predictions of the rates of degradation processes and undertake adequate mitigation measures. The combined tomographic and micromorphological studies of aggregates of 1-2 and 3-5 mm in diameter from compacted horizons of different soils have been performed for the first time. Additional diagnostic features of negative solonetz- forming processes (low open porosity of aggregates seen on tomograms and filling of a considerable part of the intraped pores with mobile substance) and the vertisol-forming processes (large amount of fine intraaggregate pores seen on tomograms and a virtual absence of humus-clay plasma in the intraped zone)—have been identified. It is shown that the combination of microtomographic and micromorphological methods is helpful for studying the pore space of compacted horizons in cultivated soils.

  10. Neoproterozic Re-Os age of a sulfide inclusion in a superdeep diamond: Implications for mantle convection beneath Juina, Brazil

    Science.gov (United States)

    Shirey, S. B.; Smit, K.; Nestola, F.; Steele, A.; Bulanova, G.; Smith, C. B.

    2015-12-01

    Diamonds from the Juina area Brazil have long been known for their sublithospheric or superdeep (e.g. from depths of 300-800 km) origins. These diamonds have yielded new information about high pressure mantle mineralogy, deep crustal recycling, diamond source fluids, and mantle transition zone water content. A type II (low N) diamond (sample J1) from the 93.1±1.5 myr old (Heaman 7IKC 1998 ) Collier 4 kimberlite was studied previously (Walter et al. Nature 2008; Bulanova et al. CMP 2010) as part of a larger suite of eclogitic-composition, inclusion-bearing type II Collier 4 diamonds with complex internal growth structure. Major and trace element analyses of mineral inclusions in these diamonds include Ca-Ti-Si perovskite, Ca-rich majoritic-garnet, clinopyroxene, olivine, jeffbenite, minerals with stoichiometries of CAS and K-hollandite phases, SiO2, FeO, native iron, low-Ni sulfides, and Ca-Mg-carbonate. The C isotopic compositions of the diamond hosts range from a δ13C of -25 to -5‰ ( J1 being -15‰). Collier 4 diamonds have been interpreted to crystallize from carbonatitic melts derived from the recycling of oceanic lithosphere at TransitionZone depths (Walter et al. Nature 2008; Bulanova et al. CMP 2010). A rare Fe-sulfide inclusion in the core of diamond J1 has been dated with the Re-Os system in order to provide age and compositional constraints on the proposed oceanic slab recycling. The rim of J1 contained inclusions of Ca-Ti-Si perovskite that yielded U-Pb age of 101±7 Ma and eclogitic (low Cr, high Ca) majorite that yielded formation pressures (Si - Al+Cr geobarometry) >8 GPa (Bulanova et al. CMP 2010). The Fe-sulfide analyzed was low Ni pyrrhotite determined to be Fe10S11 of a rare 11T polytype by single-crystal X-ray diffraction. The 27 ug interior pyrrhotite had a high Re/Os (187Re/188Os = 854) typical of MORB (Re/Os ~100) and radiogenic Os isotopic composition (187Os/188Os = 8.50±1.38) that yields a 602±16 Ma model age relative to normal mantle

  11. Tracking photosynthetic sulfide oxidation in a meromictic lake using sulfate δ34S and δ18O

    Science.gov (United States)

    Gilhooly, W. P.; Reinhard, C.; Lyons, T. W.; Glass, J. B.

    2012-12-01

    Phototrophic sulfur bacteria oxidize sulfide and fix carbon dioxide in the presence of sunlight without producing oxygen. Environmental conditions in the Paleo- and Mesoproterozoic, when atmospheric oxygen concentrations were at low levels and portions of the oceans were anoxic and sulfidic (euxinic), were conducive to widespread carbon fixation by anoxygenic photosynthesis. This pathway may have helped sustain euxinic conditions in the Proterozoic water column. With limited organic biomarker and geochemical evidence for widespread production of anoxygenic phototrophs, however, additional proxies are needed to fingerprint paleoecological and biogeochemical signals associated with photic zone euxinia. Paired δ34S and δ18O from ancient sulfates (gypsum, barite, or CAS) may offer an added constraint on the history and ecological dominance of photosynthetic S-oxidation. Sulfate-oxygen can fractionate during sulfate reduction, but the extent of isotopic enrichment is controlled either by kinetic isotope effects imparted during intracellular enzymatic steps or equilibrium oxygen exchange with ambient water. An improved understanding of these processes can be gained from modern natural environments. Mahoney Lake is a density-stratified lake located within the White Lake Basin of British Columbia. The euxinic water column supports a dense plate of purple sulfur bacteria (Amoebobacter purpureus) that thrives where free sulfide intercepts the photic zone at ~7 m water depth. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within this meromictic lake. Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S >50‰) are consistent with sulfate reduction in both the sediments and the anoxic

  12. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Dezhao, Liu; Hansen, Michael Jørgen;

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  13. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen;

    2012-01-01

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  14. Depth profiles of the inorganic chemical composition of soil water in the unsaturated zone; Tiefenprofile der anorganisch-chemischen Zusammensetzung von Bodenwasser in der ungesaettigten Zone

    Energy Technology Data Exchange (ETDEWEB)

    Hoess, J.

    1992-04-01

    Soil water up to a depth of 4 m below ground surface was analysed for its inorganic-chemical composition. It was obtained as `soil solution` by centrifuging original moist soil samples. The analysis provides depth profiles of the concentration of the major inorganic ions in soil water of well evidence. The studies were made on the environmental research test site called `Horkheimer Insel`, 70 km north of Stuttgart, which is a joint research site within the project `Wasser-Abfall-Boden` of the country of Baden-Wuerttemberg. Samples were collected mainly on two parts of the test site, one being operated by `conventional` farming techniques, the other by `sustainable` techniques, i.e. lower quantities of agrochemical and reduced tillage. The nitrat content of soil water in 4 m depth under the field of sustainable argriculture during the three tested years of cultivation was on an average only 30% of the concentration under the field of conventional agriculture. This means, the amount of nitrat, which is carried in groundwater, could be reduced to the same extend by the chosen way of sustainable agriculture. In respect to the overall salt content of soil water the analysis showed, that it is already very high in the upper soil layer (0 - 25 cm) and does not increase with increasing depth. It can be concluded, that it is determined by processes within this zone of the plant roots and of main microbiological activity. Percolation through the layers beneath this zone only provides a change in the proportion of cation or anion concentrations. (orig.). [Deutsch] Bodenwasser bis zu einer Tiefe von 4 m Flurabstand wurde auf seine anorganisch-chemische Zusammensetzung hin untersucht. Es wurde durch Zentrifugieren original feuchter Bodenproben als `Bodenloesung` gewonnen. Die Untersuchung liefert aussagekraeftige Konzentrationsprofile der anorganischen Ionen im Bodenwasser. Die Probenahme erfolgte auf dem Naturmessfeld `Horkheimer Insel`, 70 km noerdlich von Stuttgart, einem

  15. Changes in the composition of an acid mine drainage microbial community upon successive transfers in medium containing low-grade copper sulfide.

    Science.gov (United States)

    Liu, Yi; Yin, Huaqun; Liang, Yili; Shen, Li; Liu, Yao; Fu, Xian; Baba, Ngom; Zeng, Weimin; Qiu, Guanzhou; Liu, Xueduan

    2011-10-01

    A consortium of microorganisms from acid mine drainage samples was cultured in modified 9 K medium containing low-grade copper sulfide. The culture was maintained for sixty days and then transferred to fresh medium. This process was repeated three more times and a final consortium exhibiting a copper extraction rate of 89.3% was obtained. RFLP and microarrays analysis of 16S rRNA sequences retrieved from the consortia showed that Acidithiobacilluscaldus, Leptospirillumferriphilum, Sulfobacillus sp., Acidiphilium sp., and Sulfolobus spp. were represented in higher numbers in the consortia obtained in the copper-containing medium than in the original consortium. In contrast, a decrease in Acidithiobacillus ferrooxidans, Alicyclobacillus sp., Pseudomonas sp., and Sulfobacillus thermosulfidooxidans was observed. The abundance of genes related to sulfur metabolism from At. caldus and Sulfolobus spp., iron oxidation from Leptospirillum sp. and metal resistance from most of the detected microorganisms increased as the consortium was successively transferred into fresh medium. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Influence of Strain-Hardened Zones and Intermetallic Layers of Explosion Welded and Heat Treated Al/Cu Laminated Metal Composites on the Evolution of Thermal Conductivity Coefficient

    Directory of Open Access Journals (Sweden)

    Yuriy TRYKOV

    2014-09-01

    Full Text Available In this study laminated Al/Cu composite was obtained by explosion welding. The effect of strain-hardened zones and the intermetallic layer on thermal conductivity coefficient was investigated. For this purpose the specimens after explosion welding and after subsequent annealing to obtain the intermetallic layer were studied by X-ray methods and means of optical microscopy to determine the phase composition and the width of intermetallic layer. The microhardness tests were carried out to identify the width of the strain-hardened zones and the intermetallic layer. The thermal conductivity coefficient of the composite was experimentally measured to calculate the thermal properties of the strain-hardened zones and intermetallic layer. The width of the strain-hardened zone and the intermetallic layer was 80 μm and 160 μm respectively. The heat conductivity coefficients of the strain-hardened zones and intermetallic layer were 108 W/(m×K and less than 35 W/(m×K respectively. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4602

  17. Quantifying elemental compositions of primary minerals from granitic rocks and saprolite within the Santa Catalina Mountain Critical Zone Observatory

    Science.gov (United States)

    Lybrand, R. A.; Rasmussen, C.

    2011-12-01

    Granitic terrain comprises a significant area of the earth's land surface (>15%). Quantifying weathering processes involved in the transformation of granitic rock to saprolite and soil is central to understanding landscape evolution in these systems. The quantification of primary mineral composition is important for assessing subsequent mineral transformations and soil production. This study focuses on coupling detailed analysis of primary mineral composition to soil development across an array of field sites sampled from the Santa Catalina Mountain Critical Zone observatory (SCM-CZO) environmental gradient. The gradient spans substantial climate-driven shifts in vegetation, ranging from desert scrub to mixed conifer forests. The parent material is a combination of Precambrian and Tertiary aged granites and quartz diorite. Primary mineral type and composition are known to vary among the various aged granitic materials and this variability is hypothesized to manifest as significant variation in regolith forming processes across the SCM-CZO. To address this variability, the mineral composition and mineral formulae of rock and saprolite samples were determined by electron microprobe chemical analyses. The rocks were pre-dominantly quartz, biotite, muscovite, orthoclase and calcium/sodium-rich plagioclase feldspars. Trace minerals observed in the samples included sphene, rutile, zircon, garnet, ilmenite, and apatite. Mineral formulae from electron microprobe analyses were combined with quantitative x-ray diffraction (QXRD) and x-ray fluorescence (XRF) data to quantify both primary and secondary mineralogical components in soil profiles from each of the field sites. Further, electron microprobe analyses of <2mm mixed conifer saprolite revealed weathered plagioclase grains coated with clay-sized particles enriched in silica and aluminum (~25% and 15%, respectively), suggesting kaolin as the secondary phase. The coatings were interspersed within each plagioclase grain, a

  18. Monitoring sulfide and sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.S.

    1995-12-31

    Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

  19. Iron sulfides in mudstones within the carbonaceous sequence of Donets Basin

    Energy Technology Data Exchange (ETDEWEB)

    Kizilshtein, L.Y.; Nastavkin, A.V. [Rostov State University, Rostov Na Donu (Russian Federation)

    2003-02-01

    The genesis of local compact segregations of iron sulfide (pyrite) in mudstones at the roof of some coal seams in the Donets Basin (Donbas) is examined. Arguments presented in the work show that sulfides were formed as a result of bacterial sulfate reduction and hydrogen sulfide generation in zones of organic matter concentration. The lack of any signs of influx of alien components testifies to in situ sulfide accumulations at the syngenetic or early diagenetic stage in bottom sediments of the basin. The shape and structure of pyrite segregations suggest that they could be 'sulfide bioherms' occasionally subjected to mechanical deformation in a liquid mud under the influence of gravitational force or external mechanical (possibly seismic) loads. The obtained data can serve as an additional source of information pertaining to the formation conditions of sulfide ore deposits.

  20. Water composition in the unsaturated zone at Sete Cidades central volcano (S. Miguel, Azores, Portugal)

    Science.gov (United States)

    Cruz, J.; Silva, M.; Mendonça, J.; Dias, I.; Prudêncio, I.

    2009-04-01

    A field study was developed at Sete Cidades, the westernmost of the three active composite volcanoes that dominate the geology of São Miguel, the largest of the nine islands from the Azores archipelago. Research methodology comprehends the characterization of soil-water composition at several depths, sampled by means of ceramic suction cups. Previously to their installation, cups were all submitted to several stages of washing, first in the laboratory with supra pure water, until aliquot conductivity stabilizes, and after in the field. This study was planned in order to study the water pollution due to agriculture, one of the main economic activities in the Azores, as shown by the gross value added to regional product. The negative effects of groundwater pollution due to agriculture have been reported in the majority of the nine islands, reflected by high contents of nitrogen species, derived from the inadequate use of synthetic and organic fertilizers, as well as from animal wastes leaching, or also by microbiology parameters. The relation between water pollution and agriculture results in some cases in the failure to comply regarding EU and national water quality regulations, through quality deterioration and compromising groundwater as strategic natural resource in the Azores. The studied area corresponds to Sete Cidades volcano caldera, a 5 km-diameter circular shaped depression, contoured by steep walls from 30 m high up to 400 m. In order to characterize unsaturated water composition in the caldera floor, five pasture locations were selected and monitored, as well as one site with the same physical conditions, but without agricultural activity. From the 5 pasture lands we discuss further results obtained in the so-called Pavão I (Pa I), which corresponds to the most extensive data set. On this site, 6 suction cups were installed, at depths 0.35 m, 0.7 m, 1 m, 1.3 m, 1.6 m and 1.9 m. In the site without agricultural activity, in the vicinity of Sete Cidades

  1. Synthesis and characterization of CdS nanocrystallites and OMWCNT-supported cadmium sulfide composite and their photocatalytic activity under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Amol S. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India); Garje, Shivram S., E-mail: ssgarje@chem.mu.ac.in [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India); Revaprasadu, Neerish [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa, 3886 (South Africa)

    2016-11-01

    CdS nanocrystallites and CdS- oxidized multiwalled carbon nanotubes (OMWCNT) composite were prepared by the solvothermal decomposition of a single-source molecular precursor, [Cd(pip.dtc){sub 2}] (pip.dtc = piperidine dithiocarbamate) in the presence of ethylene glycol. The as prepared CdS nanocrystallites and CdS-OMWCNT composite were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-vis and Raman spectroscopy. Peak broadening in the XRD shows the formation of nanocrystalline CdS. TEM images of CdS nanocrystallites revealed the nearly spherical shape morphology of the particles, whereas, TEM images of composite showed the deposition of CdS nanocrystallites on the OMWCNT. EDX measurements matches with a 1:1 stoichiometry of Cd and S in CdS nanocrystallites, whereas, that of the composite showed the presence of Cd and S along with C. The vibrational properties of CdS nanocrystallites and their composite with OMWCNT were studied by Raman spectroscopy. Furthermore, the photocatalytic activity studies for the degradation of methylene blue under visible light irradiation using these materials were carried out. The surface area calculated using BET surface analyzer for CdS-OMWCNT composite (148.31 m{sup 2}/g) was found to be more compared to bare CdS nanocrystallites (56.78 m{sup 2}/g). The CdS-OMWCNT composite exhibited very good photocatalytic activity for the degradation of methylene blue under visible light irradiation which has been attributed to the increased surface area and synergistic effect in the composite compared to bare CdS nanocrystallites. - Highlights: • The carbon based nanocomposite of CdS (CdS-OMWCNT) have been prepared. • Simple solvothermal decomposition method has been used. • Single-source molecular precursor in presence of carbon nanotubes has been employed. • The photocatalytic activity of CdS NPs and CdS-OMWCNT composite

  2. Changes in composition and pore space of sand rocks in the oil water contact zone (section YU1 3-4, Klyuchevskaya area, Tomsk region)

    Science.gov (United States)

    Nedolivko, N.; Perevertailo, T.; Pavlovec, T.

    2016-09-01

    The article provides an analysis of specific features in changes of rocks in the oil water contact zone. The object of study is the formation YU1 3-4 (J3o1) of Klyuchevskaya oil deposit (West Siberian oil-gas province, Tomsk region). The research data allow the authors to determine vertical zoning of the surface structure and identify the following zones: oil saturation (weak alteration), bitumen-content dissolution, non-bitumen-content dissolution, cementation, including rocks not affected by hydrocarbon deposit. The rocks under investigation are characterized by different changes in composition, pore space, as well as reservoir filtration and volumetric parameters. Detection of irregularity in distribution of void- pore space in oil-water contact zones is of great practical importance. It helps to avoid the errors in differential pressure drawdown and explain the origin of low-resistivity collectors.

  3. [The characteristics of microstructure and chemical compositions of K-feldspar, sphene and zircon with zoning structure].

    Science.gov (United States)

    Liu, Chun-Hua; Wu, Cai-Lai; Lei, Min; Qin, Hai-Peng; Li, Ming-Ze

    2013-08-01

    K-feldspar, sphene and zircon in quartz monzonite from Shahewan, south Qinling, showing strong zoning structure. Characteristics of microstructure and chemical compositions of K-feldspar, sphene and zircon with zoning structure were investigated using advanced instruments of electron probe micro analyses equipped with wavelength dispersive spectrometer (EPM-WDS), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and laser ablation--inductively coupled plasma--mass spectrometry (LA-ICP-MS). Our study suggests that K+ could be substituted by small amounts of Na+, Ca2+, Ba2+, Fe2+ and Ce3+. Ca2+ in sphene could be replaced by V3+, Ce3+, Ba2+ and Ti4+ could be substituted by both Fe2+ and Al3+. Zircon contains trace elements like Fe, Th, U, Nb, Ta, Y, Hf, Yb and Pb. Concentration of Si, Al, K, Ca, Na, Mg and Ba in K-feldspar ranked from high to low, among which the contents of K and Na are negatively correlated, the lighter part of BSE images featuring K-feldspar is attributed to comparably higher Ba content, additionally, Si and K contents are elevated while Na content decreased rimward. Ca, Si, Ti, Ba, V, Ce, Al and Fe concentration listed downward, among which higher iron content corresponds to brighter portion of BSE images. Element concentration of zircon could be ranked from high to low as Zr, Si, Nd, Ce, Hf, U, Pb and Th, in which Hf and Zr exhibit negatively correlated. Zr concentration increased while Hf, U and Th concentration decreased from core to rim.

  4. RESEARCH ON TOUGHENING OF POLY(PHENYLENE SULFIDE)/HIGH DENSITY POLYETHYLENE/GLASS FIBER COMPOSITES%聚苯硫醚/高密度聚乙烯/玻纤复合材料增韧研究

    Institute of Scientific and Technical Information of China (English)

    孙海青; 谭洪生; 王延刚; 李丽平

    2011-01-01

    The maleic anhydride grafted polyethylene ( PE-g-MAH ) was used as the interfacial compatibilizer, poly ( phenylene sulfide ) ( PPS ), high density polyethylene ( PE-HD ) and glass fiber ( GF ) were blended by a mixer, and the composites were gained. The impact toughness, morphology of impact fracture surfaces of the specimens were investigated, and toughening mechanism was discussed. The results showed that the notch impact strength of the composite was improved efficiently by the blending of PE-HD and GF, and increased obviously with increase of PE-HD content. The impact toughness increased with increase of PE-g-MAH content at first, but it decreased slowly when the mass fraction of PE-g-MAH exceeded 8%. The analysis of SEM showed that the interfacial bond of the composite was improved obviously by PE-g-MAH. In the composite of PPS/PE-HD/ GF, flexile PE-HD could run through the composite system and PE-g-MAH could enhance the interfacial bond, which increased the toughness of the composites obviously.%以马来酸酐接枝聚乙烯( PE-g-MAH)作为界面增容剂,将聚苯硫醚(PPS)、高密度聚乙烯(PE-HD)和玻璃纤维(GF)在转矩流变仪中混炼制得复合材料,并对其冲击性能、断面形貌及增韧机理进行了分析.结果表明,PPS基体中添加PE-HD与GF可有效提高复合材料的缺口冲击强度,且随PE-HD含量的增加显著提高.随着PE-g-MAH含量的增加,复合材料的缺口冲击强度显著提高.但当PE-g-MAH质量分数达到8%时,缺口冲击强度反而下降.扫描电子显微镜( SEM)分析表明,PE-g-MAH明显地改善了复合材料界面粘结性.PPS/PE-HD/GF复合材料中,韧性良好的PE-HD贯穿于复合材料,PE-g-MAH作为增容剂对界面的改进起到了明显的增韧效果.

  5. Distribution and Composition of Particulate Organic Carbon along Oregon's Upwelling Zone

    Science.gov (United States)

    Goni, M. A.; Holser, R. R.; Hales, B. R.; Succes Team

    2010-12-01

    Direct measurements of particulate organic carbon (POC) concentrations are needed to quantitatively understand the carbon cycle in Eastern Boundary ocean margins. However, in the past these measurements have been somewhat restricted due to the time-intensive nature of the sample collection and manual filtration procedures. To increase temporal and spatial coverage of POC distributions, we designed and built a semi-automated filtration system (SAFS) linked to a towed profiling vehicle with pumping capabilities. This set up allowed us to perform filtrations at high frequency and measure POC concentrations throughout the entire water column along several shore-perpendicular transects across the Oregon shelf. We combined these data with in-situ optical measurements (i.e., beam transmission, chlorophyll fluorescence and optical backscatter) and characterized several distinct pools of particles within different geographical and depth regions of the water column off the central Oregon Coast. For example, early in the upwelling season (May 2009) surface waters were characterized by elevated POC concentrations (> 20 uM) and displayed significant patchiness with areas of very high concentrations (> 80 uM). Below 50 m POC concentrations were uniformly low (water particles were carbon and chlorophyll rich but had elevated backscatter properties that approached those of particles in the BBL. These compositions indicate phytoplankton contributed predominantly to the particle pool in both surface and mid-depth waters, with the main differences between them being overall concentration (much higher at the surface) and particle size (much smaller at the mid-depths). The lack of fresh algal materials in the BBL suggests labile OM transport to the deeper regions of the water column had not occurred at this early stage in the upwelling season. The elevated backscatter properties of BBL particles are consistent with high lithogenic content and resuspended seabed provenance.

  6. Impact of fuel composition on the recirculation zone structure and its role in lean premixed flame anchoring

    KAUST Repository

    Hong, Seunghyuck

    2015-01-01

    © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. We investigate the dependence of the recirculation zone (RZ) size and structure on the fuel composition using high-speed particle image velocimetry (PIV) and chemiluminescence measurements for C3H8/H2/air lean premixed flames stabilized in a backward-facing step combustor. Results show an intricate coupling between the flame anchoring and the RZ structure and length. For a fixed fuel composition, at relatively low equivalence ratios, the time-averaged RZ is comprised of two counter rotating eddies: a primary eddy (PE) between the shear layer and the bottom wall; and a secondary eddy (SE) between the vertical step wall and the PE. The flame stabilizes downstream of the saddle point of the dividing streamline between the two eddies. As equivalence ratio is raised, the flame moves upstream, pushing the saddle point with it and reducing the size of the SE. Higher temperature of the products reduces the velocity gradient in the shear layer and thus the reattachment length. As equivalence ratio approaches a critical value, the saddle point reaches the step and the SE collapses while the flame starts to exhibit periodic flapping motions, suggesting a correlation between the RZ structure and flame anchoring. The overall trend in the flow field is the same as we add hydrogen to the fuel at a fixed equivalence ratio, demonstrating the impact of fuel composition on the flow field. We show that the reattachment lengths (LR), which are shown to encapsulate the mean RZ structure, measured over a range of fuel composition and equivalence ratio collapse if plotted against the strained consumption speed (Sc). Results indicate that for the flame to remain anchored, the RZ structure should satisfy lR,isothermal/L R,reacting · S c/U ∞ ∼ 0.1. If this criterion cannot be met, the flame blows off, flashes back or becomes thermoacoustically unstable, suggesting a Damköhler-like criterion for

  7. Geology, ore facies and sulfur isotopes geochemistry of the Nudeh Besshi-type volcanogenic massive sulfide deposit, southwest Sabzevar basin, Iran

    Science.gov (United States)

    Maghfouri, Sajjad; Rastad, Ebrahim; Mousivand, Fardin; Lin, Ye; Zaw, Khin

    2016-08-01

    . Chloritization, silicification, sericitization and epidotization are the main wall-rock alterations; alteration intensity increases towards the stringer zone. The δ34S composition of the sulfides ranges from -1.5‰ to +3.69‰ with a general increase of δ34S ratios of massive ore facies to stockwork zone. The heavier values indicate that some of the sulfur was derived from seawater sulfate that was ultimately thermochemically reduced in deep hydrothermal reaction zones. Sulfur isotopes, along with sedimentological, textural, petrological, mineralogical, and geochemical evidences, suggest that this deposit should be classified as a Besshi-type VMS ore deposit.

  8. Pyritization processes and greigite formation in the advancing sulfidization front in the Upper Pleistocene sediments of the Black Sea

    DEFF Research Database (Denmark)

    Neretin, LN; Bottcher, ME; Jørgensen, BB

    2004-01-01

    Pyritization in late Pleistocene sediments of the Black Sea is driven by sulfide formed during anaerobic methane oxidation. A sulfidization front is formed by the opposing gradients of sulfide and dissolved iron. The sulfidization processes are controlled by the diffusion flux of sulfide from above...... and by the solid reactive iron content. Two processes of diffusion-limited pyrite formation were identified. The first process includes pyrite precipitation with the accumulation of iron sulfide precursors with the average chemical composition of FeSn (n = 1.10-1.29), including greigite. Elemental sulfur...... and polysulfides, formed from H,S by a reductive dissolution of Fe(Ill)-containing minerals, serve as intermediates to convert iron sulfides into pyrite. In the second process, a "direct" pyrite precipitation occurs through prolonged exposure of iron-containing minerals to dissolved sulfide. Methane-driven sulfate...

  9. Diffused vs. Focused Flow - Metaproteogenomic Insights into Effects of Hydrothermal Fluid Flow on Metal-Sulfide Chimney Colonizing Biofilms

    Science.gov (United States)

    Pjevac, P.; Markert, S.; Richter, M.; Gruber-Vodicka, H.; Schweder, T.; Amann, R.; Meyerdierks, A.

    2014-12-01

    At many sites of hydrothermal discharge in the deep-sea, the deposition of metal sulfides from hydrothermal fluids leads to the formation of geological structures known as hydrothermal chimneys. The mixing of reduced hydrothermal fluids with oxygenated seawater leads to the formation of steep redox gradients within the chimney walls. These gradients facilitate the co-existence of metabolically diverse microorganisms in the narrow habitable zone of hydrothermal chimney walls. However, the overall composition of chimney-associated microbial community is usually of low complexity and represents an environment suitable for metaomic-based studies. We used metagenomic and metaproteomic tools to compare microbial communities colonizing two metal-sulfide chimneys from the Manus Basin back-arc spreading center in the Bismarck Sea off Papua New Guinea. These chimneys were supplied by the same source hydrothermal fluids, but exhibited different fluid flow regimes. One chimney (RMR5) had a focused venting edifice, while the other (RMR-D) displayed diffuse fluid efflux on its entire outer surface. Although the microbial diversity of both chimneys is similar and dominated by mesophilic Epsilonproteobacteria, our results indicate a strong structuring effect of hydrothermal fluid flow regime on chimney-associated biofilms. The microbial community composition indicates a homogeneous colonization of the diffuse chimney walls. In contrast, the walls of the focused venting chimney appear to be colonized in layers reflecting different temperature tolerances of the dominant microorganisms. Sulfide-oxidation is likely the key metabolism in both chimneys, which is in line with the high sulfide content of the source hydrothermal fluid. However, preliminary metaproteome analysis indicates high activity of low-abundant methanotrophic Bacteria in the diffuser chimney walls. This finding is particularly interesting in light of the very low methane content of the source hydrothermal fluid

  10. Sulfide detoxification in plant mitochondria.

    Science.gov (United States)

    Birke, Hannah; Hildebrandt, Tatjana M; Wirtz, Markus; Hell, Rüdiger

    2015-01-01

    In contrast to animals, which release the signal molecule sulfide in small amounts from cysteine and its derivates, phototrophic eukaryotes generate sulfide as an essential intermediate of the sulfur assimilation pathway. Additionally, iron-sulfur cluster turnover and cyanide detoxification might contribute to the release of sulfide in mitochondria. However, sulfide is a potent inhibitor of cytochrome c oxidase in mitochondria. Thus, efficient sulfide detoxification mechanisms are required in mitochondria to ensure adequate energy production and consequently survival of the plant cell. Two enzymes have been recently described to catalyze sulfide detoxification in mitochondria of Arabidopsis thaliana, O-acetylserine(thiol)lyase C (OAS-TL C), and the sulfur dioxygenase (SDO) ethylmalonic encephalopathy protein 1 (ETHE1). Biochemical characterization of sulfide producing and consuming enzymes in mitochondria of plants is fundamental to understand the regulatory network that enables mitochondrial sulfide homeostasis under nonstressed and stressed conditions. In this chapter, we provide established protocols to determine the activity of the sulfide releasing enzyme β-cyanoalanine synthase as well as sulfide-consuming enzymes OAS-TL and SDO. Additionally, we describe a reliable and efficient method to purify OAS-TL proteins from plant material.

  11. The acute 1-week effects of the Zone diet on body composition, blood lipid levels, and performance in recreational endurance athletes.

    Science.gov (United States)

    Jarvis, Mark; McNaughton, Lars; Seddon, Alan; Thompson, Dylan

    2002-02-01

    The aim of this study was to examine the effects of a 7-day Zone diet compared with a normal diet on maximal oxygen uptake (V(O)2 max), running time to exhaustion during endurance performance, and body composition. Eight men, with the following physical characteristics (mean +/- SE), participated in this study: age, 26.1 +/- 1.9 years; height, 178 +/- 1.7 cm; mass, 70.7 +/- 2.1 kg; and V(O)2 max, 54.6 +/- 3.1 ml x kg(-1) x min(-1). All subjects undertook pretesting for V(O)2 max, time to exhaustion (80% V(O)2 max), and body composition (Biostat 1500) before following either the normal diet or the Zone diet for 7 days. These performance trials were performed before and after the dietary period. There was a significant (p diet to 1,994 +/- 438 kcal on the Zone diet. Subjects showed a significant reduction (p diet to 34.11 +/- 7.01 minutes for the Zone diet. In conclusion, the claim of the authors of the Zone diet that performance time and V(O)2 max can be improved was not shown in this 1-week research trial. We would suggest that this is not a nutritional strategy that athletes should use until further work has been conducted.

  12. Maternal Genetic Composition of a Medieval Population from a Hungarian-Slavic Contact Zone in Central Europe.

    Science.gov (United States)

    Csákyová, Veronika; Szécsényi-Nagy, Anna; Csősz, Aranka; Nagy, Melinda; Fusek, Gabriel; Langó, Péter; Bauer, Miroslav; Mende, Balázs Gusztáv; Makovický, Pavol; Bauerová, Mária

    2016-01-01

    The genetic composition of the medieval populations of Central Europe has been poorly investigated to date. In particular, the region of modern-day Slovakia is a blank spot in archaeogenetic research. This paper reports the study of mitochondrial DNA (mtDNA) in ancient samples from the 9th-12th centuries originating from the cemeteries discovered in Nitra-Šindolka and Čakajovce, located in western Slovakia (Central Europe). This geographical region is interesting to study because its medieval multi-ethnic population lived in the so-called contact zone of the territory of the Great Moravian and later Hungarian state formations. We described 16 different mtDNA haplotypes in 19 individuals, which belong to the most widespread European mtDNA haplogroups: H, J, T, U and R0. Using comparative statistical and population genetic analyses, we showed the differentiation of the European gene pool in the medieval period. We also demonstrated the heterogeneous genetic characteristics of the investigated population and its affinity to the populations of modern Europe.

  13. Microplastics in the surface sediments from the Beijiang River littoral zone: Composition, abundance, surface textures and interaction with heavy metals.

    Science.gov (United States)

    Wang, Jundong; Peng, Jinping; Tan, Zhi; Gao, Yifan; Zhan, Zhiwei; Chen, Qiuqiang; Cai, Liqi

    2017-03-01

    While large quantities of studies on microplastics in the marine environment have been widely carried out, few were available in the freshwater environment. The occurrence and characteristics, including composition, abundance, surface texture and interaction with heavy metals, of microplastics in the surface sediments from Beijiang River littoral zone were investigated. The concentrations of microplastics ranged from 178 ± 69 to 544 ± 107 items/kg sediment. SEM images illustrated that pits, fractures, flakes and adhering particles were the common patterns of degradation. Chemical weathering of microplastics was also observed and confirmed by μ-FTIR. EDS spectra displayed difference in the elemental types of metals on the different surface sites of individual microplastic, indicating that some metals carried by microplastics were not inherent but were derived from the environment. The content of metals (Ni, Cd, Pb, Cu, Zn and Ti) in microplastics after ultrasonic cleaning has been analyzed by ICP-MS. Based on data from the long-term sorption of metals by microplastics and a comparison of metal burden between microplastics, macroplastics and fresh plastic products, we suggested that the majority of heavy metals carried by microplastics were derived from inherent load.

  14. A study of cathodoluminescence and trace element compositional zoning in natural quartz from volcanic rocks: mapping titanium content in quartz.

    Science.gov (United States)

    Leeman, William P; MacRae, Colin M; Wilson, Nick C; Torpy, Aaron; Lee, Cin-Ty A; Student, James J; Thomas, Jay B; Vicenzi, Edward P

    2012-12-01

    This article concerns application of cathodoluminescence (CL) spectroscopy to volcanic quartz and its utility in assessing variation in trace quantities of Ti within individual crystals. CL spectroscopy provides useful details of intragrain compositional variability and structure but generally limited quantitative information on element abundances. Microbeam analysis can provide such information but is time-consuming and costly, particularly if large numbers of analyses are required. To maximize advantages of both approaches, natural and synthetic quartz crystals were studied using high-resolution hyperspectral CL imaging (1.2-5.0 eV range) combined with analysis via laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Spectral intensities can be deconvolved into three principal contributions (1.93, 2.19, and 2.72 eV), for which intensity of the latter peak was found to correlate directly with Ti concentration. Quantitative maps of Ti variation can be produced by calibration of the CL spectral data against relatively few analytical points. Such maps provide useful information concerning intragrain zoning or heterogeneity of Ti contents with the sensitivity of LA-ICPMS analysis and spatial resolution of electron microprobe analysis.

  15. Oxygen and hydrogen isotope compositions of eclogites and associated rocks from the Eastern Sesia zone (Western Alps, Italy)

    Science.gov (United States)

    Desmons, J.; O'Neil, J.R.

    1978-01-01

    Oxygen and hydrogen isotope analyses have been made of mineral separates from eclogites, glaucophanites and glaucophane schists from the eastern Sesia zone (Italian Western Alps). Regularities in (1) hydrogen isotope compositions, (2) order of 18O enrichment among coexisting minerals, and (3) ?? 18O (quartz-rutile) and ?? 18O (quartz-phengite) imply attainment of a high degree of isotopic equilibrium. However, some scattering of ??18O values of individual minerals indicates that the eclogitic assemblage did not form in the presence of a thoroughly pervasive fluid. Minerals from an eclogitic lens enclosed in marble have ??18O values distinctly different from those measured in the other rocks. The ??18O values are high in comparison with other type C eclogites of the world, and it is proposed that the fluid present during the high pressure metamorphism has to a large extent been inherited from the precursor rocks of amphibolite facies. An average formation temperature of 540 ?? C is inferred from the oxygen isotope fractionations between quartz and rutile and between quartz and white mica. This temperature is in accordance with petrologic considerations and implies subduction of the precursor rocks into the upper mantle to achieve the high pressures required. ?? 1978 Springer-Verlag.

  16. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen

    2012-01-01

    oxidizing bacteria but several fungal families including Trichocomaceae. A positive correlation was found between the presence of mold and sulfide uptake. However there have been no reports on fungi metabolizing hydrogen sulfide. We hypothesize that the mold increases the air exposed surface, enabling...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  17. XAFS characterization of industrial catalysts: in situ study of phase transformation of nickel sulfide

    Science.gov (United States)

    Wang, J.; Jia, Z.; Wang, Q.; Zhao, S.; Xu, Z.; Yang, W.; Frenkel, A. I.

    2016-05-01

    The online sulfiding process for nickel-contained catalyst often ends up with a nickel sulfide mixture in refinery plant. To elucidate the local environment of nickel and its corresponding sulfur species, a model catalyst (nickel sulfide) and model thermal process were employed to explore the possibilities for characterization of real catalysts in industrial conditions. The present investigation shows effectiveness of in situ XANES and EXAFS measurements for studying the phase stability and phase composition in these systems, which could be used to simulate real sulfiding process in industrial reactions, such as hydrodesulfurizations of oil.

  18. Progressive assembly of a massive layer of ignimbrite with a normal-to-reverse compositional zoning: the Zaragoza ignimbrite of central Mexico

    Science.gov (United States)

    Carrasco-Núñez, Gerardo; Branney, Michael J.

    2005-11-01

    The Zaragoza ignimbrite and two enclosing rhyodacite pumice fall layers were emplaced during the 15 km3 (DRE), ˜0.1 Ma Zaragoza eruption from Los Humeros volcanic centre, 180 km east of Mexico City. The ignimbrite comprises several massive flow-units, the largest of which locally exceeds 20 m in thickness and is regionally traceable. It comprises massive lapilli-ash with vertical elutriation pipes, and has a fine-grained inverse-graded base and a pumice concentration zone at the top. It also exhibits an unusual gradational ‘double’ vertical compositional zonation that is widely traceable. A basal rhyodacitic (67.6-69 wt% SiO2) zone grades up via a mixed zone into a central andesitic (58-62 wt% SiO2) zone, which, in turn, grades up into an upper rhyodacitic (67.6-69 wt% SiO2) zone. Zoning is also defined by vertical variations in lithic clast populations. We infer that pyroclastic fountaining fed initially rhyodacite pumice clasts to a sustained granular fluid-based pyroclastic density current. The composition of the pumice clasts supplied to the current then gradually changed, first to andesite and then back to rhyodacite. Inverse grading at the base of the massive layer may reflect initial waxing flow competence. The pumice concentration at the top of the massive layer is entirely rhyodacitic and was probably deposited during waning stages of the current, when the supply of andesitic pumice clasts had ceased. The return to rhyodacitic composition may have been the result of eruption-conduit modification during collapse of Los Potreros caldera, marked in the ignimbrite by a widespread influx of hydrothermally altered lithic blocks, and/or a decrease in draw-up depth from a compositionally stratified magma chamber as the eruptive mass flux waned. The massive layer of ignimbrite thins locally to less than 2 m, yet it still shows the double zonation. Correlation of the zoning suggests that the thin massive layer is stratigraphically condensed, and aggraded

  19. Intrusive rocks of the Holden and Lucerne quadrangles, Washington; the relation of depth zones, composition, textures, and emplacement of plutons

    Science.gov (United States)

    Cater, Fred W.

    1982-01-01

    serpentine. These occur either as included irregular masses in later intrusives or as tectonically emplaced lenses in metamorphic rocks. Also of uncertain age but probably much younger, perhaps as young as Eocene, are larger masses of hornblendite and hornblende periodotite that grade into hornblende gabbro. These are exposed on the surface and in the underground workings of the Holden mine. Oldest of the granitoid intrusives are the narrow, nearly concordant Dumbell Mountain plutons, having a radiometric age of about 220 m.y. They consist of gneissic hornblende-quartz diorite and quartz diorite gneiss. Most contacts consist of lit-par-lit zones, but some are gradational or more rarely sharp. The plutons are typically catazonal. Closely resembling the Dumbell Mountain plutons in outcrop appearance, but differing considerably in composition, are the Bearcat Ridge plutons. These consist of gneissic quartz diorite and granodiorite. The Bearcat Ridge plutons are not in contact with older dated plutons, but because their textural and structural characteristics so closely resemble those of the Dumbell Mountain plutons, they are considered to be the same age. Their composition, however, is suggestive of a much younger age. Cutting the Dumbell Mountain plutons is the Leroy Creek pluton, consisting of gneissic biotite-quartz diorite and trondjhemite. The gneissic foliation in the Leroy Creek is characterized by a strong and pervasive swirling. Cutting both the Dumbell Mountain and Leroy Creek plutons are the almost dikelike Seven-fingered Jack plutons. These range in composition from gabbro to quartz diorite; associated with them are contact complexes of highly varied rocks characterized by gabbro and coarse-grained hornblendite. Most of the rocks are gneissic, but some are massive and structureless. Radiometric ages by various methods range from 100 to 193 m.y. Dikes, sills, small stocks, and irregular clots of leucocratic quartz diorite and granodiorite are abundant in t

  20. A facile one-pot synthesis of copper sulfide-decorated reduced graphene oxide composites for enhanced detecting of H2O2 in biological environments.

    Science.gov (United States)

    Bai, Jing; Jiang, Xiue

    2013-09-03

    The high levels of H2O2 are closely associated with cancer and progressive neurodegenerative diseases, such as Parkinson's disease. In this study, we developed a novel CuS nanoparticle-decorated reduced graphene oxide-based electrochemical biosensor for the reliable detection of H2O2. The new electrocatalyst, CuS/RGO composites was successfully prepared by heating the mixture of CuCl2 and Na2S aqueous solutions in the presence of PVP-protected graphene oxide at 180 °C. A potential application of CuS/RGO composite-modified electrode as a biosensor to monitor H2O2 has been investigated. The steady-state current response increases linearly with H2O2 concentration from 5 to 1500 μM with a fast response time of less than 2 s. The detection limit (3σ) for determination of H2O2 has been estimated to be 0.27 μM, which was lower than certain enzymes and noble metal nanomaterial-based biosensors. In addition, the study of storage time on the amperometric response of the sensor indicates super stability. Due to these remarkable analytical advantages, the as-made sensor was applied to determine the H2O2 levels in human serum and urine samples and H2O2 released from human cervical cancer cells with satisfactory results. These results demonstrate that this new nanocomposite with the high surface area and electrocatalytic activity is a promising candidate for use as an enhanced electrochemical sensing platform in the design of nonenzymatic biosensors.

  1. The influence of sulfur pressure on sulfidation behaviour of NiCoCrAl(Y) alloys at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska, E. (School of Mining and Metallurgy, Krakow (Poland). Dept. of Solid State Chemistry); Roszczynialska, E. (School of Mining and Metallurgy, Krakow (Poland). Dept. of Solid State Chemistry); Zurek, Z. (Cracow Univ. of Technology (Poland). Inst. of Inorganic Chemistry and Technology)

    1994-06-01

    Sulfidation of alloy having nominal composition Ni-23Co-19Cr-12Al (wt%) with and without the addition of 0.6% yttrium was studied at temperatures 1073-1273 K in sulfur vapor at atmospheric pressure and in H[sub 2]/H[sub 2]S gas mixtures at sulfur pressure of 10[sup -3] and 10[sup -1.5] Pa. Sulfidation runs were followed thermogravimetrically. Phase and chemical composition of sulfide scales and scale morphologies were determined by means of XRD, EDX, EPM and SEM analyses. After certain initial period sulfidation of both materials followed approximately a parabolic rate law. The estimated sulfidation rates for each alloy increased with sulfur pressure and temperature. The sulfide scales on both materials showed complex microstructures and compositions, depending on sulfidation conditions, with several sulfide and sulfospinel phases present, such as (Ni, Co)S, (Ni, Co)[sub 3]S[sub 4], (Ni, Co)Cr[sub 2]S[sub 4], (Cr, Ni, Co)Al[sub 2]S[sub 4] or (Cr, Ni, Co)S and (Cr, Ni, Co)[sub 3]S[sub 4]. There was no evidence of yttrium segregation either to the grain boundary regions in the scale or to the alloy/scale interface. Yttrium dissolved in the sulfide phases and accelerated the sulfidation process. This behaviour was ascribed to the doping effect. (orig.)

  2. Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

    Science.gov (United States)

    Chang, Y.; Zhou, D.; Wang, Y. L.; Huang, H. H.

    2016-12-01

    This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker's micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

  3. Nitrogen Isotopic Composition of Proteinaceous Coral Skeletal Amino Acids Records Change in Source Nitrate to the Euphotic Zone in the Western Tropical Pacific

    Science.gov (United States)

    Williams, B.; Thibodeau, B.; Chikaraishi, Y.; Ohkouchi, N.; Grottoli, A. G.

    2014-12-01

    Instrumental and proxy data and global climate model experiments indicate a multi-decadal shoaling of the western tropical Pacific (WTP) thermocline potentially related to a shift in ENSO frequency. In the WTP, the nutricline coincides with the thermocline, and a shoaling of the nutricline brings more nitrate-rich seawater higher in the water column and within the sunlit euphotic zone. In the nutrient-poor WTP, this incursion of nitrate-rich water at the bottom of the euphotic zone may stimulate productivity in the water column. However, there is a general paucity of measurements below the surface with which to investigate recent changes in seawater chemistry. Nitrogen isotope (δ15N) measurements of particulate organic matter (POM) can elucidate the source of nitrogen to the WTP and related trophic dynamics. This POM is the food source to the long-lived proteinaceous corals, and drives the nitrogen isotopic composition of their skeleton. Here, we report time series δ15N values from the banded skeletons of proteinaceous corals from offshore Palau in the WTP that provide proxy information about past changes in euphotic zone nitrogen dynamics. Bulk skeletal δ15N values declined between 1977 and 2010 suggesting a progressively increasing contribution of deep water with isotopically-light nitrate to the euphotic zone and/or a shortening of the planktonic food web. Since only some amino acids are enriched in δ15N with each trophic transfer in a food web, we measured the δ15N composition of seven individual amino acids in the same coral skeleton. The δ15N time series of the individual amino acids also declined over time, mirroring the bulk values. These new data indicate that the changes in the source nitrogen to the base of the euphotic zone drives a decline in coral skeletal δ15N values, consistent with the shoaling nutricline, with no coinciding alteration of the trophic structure in the WTP.

  4. Determination of the compositions of the DIGM zone in nanocrystalline Ag/Au and Ag/Pd thin films by secondary neutral mass spectrometry

    Directory of Open Access Journals (Sweden)

    Gábor Y. Molnár

    2016-03-01

    Full Text Available Alloying by grain boundary diffusion-induced grain boundary migration is investigated by secondary neutral mass spectrometry depth profiling in Ag/Au and Ag/Pd nanocrystalline thin film systems. It is shown that the compositions in zones left behind the moving boundaries can be determined by this technique if the process takes place at low temperatures where solely the grain boundary transport is the contributing mechanism and the gain size is less than the half of the grain boundary migration distance. The results in Ag/Au system are in good accordance with the predictions given by the step mechanism of grain boundary migration, i.e., the saturation compositions are higher in the slower component (i.e., in Au or Pd. It is shown that the homogenization process stops after reaching the saturation values and further intermixing can take place only if fresh samples with initial compositions, according to the saturation values, are produced and heat treated at the same temperature. The reversal of the film sequence resulted in the reversal of the inequality of the compositions in the alloyed zones, which is in contrast to the above theoretical model, and explained by possible effects of the stress gradients developed by the diffusion processes itself.

  5. Facile one-pot synthesis of spherical zinc sulfide-carbon nanocomposite powders with superior electrochemical properties as anode materials for Li-ion batteries.

    Science.gov (United States)

    Jang, Yong Seung; Kang, Yun Chan

    2013-10-21

    A novel and simple one-pot method of systematically synthesizing spherical metal sulfide-carbon composite powders is reported for the first time. The zinc sulfide-carbon composite is selected as the first target material. The prepared composite powders show superior electrochemical properties as anode materials for lithium-ion batteries.

  6. Compositional Zoning and Mn-Cr Systematics in Carbonates from the Y791198 CM2 Carbonaceous Chondrite

    Science.gov (United States)

    Brearley, Adrian J.; Hutcheon, Ian D.; Browning, Lauren

    2001-01-01

    Cathodoluminescence and microprobe analyses show that carbonates in Y791198 exhibit complex zoning. Cr-Mn dating suggests formation of carbonates 10 Ma after CAI formation Additional information is contained in the original extended abstract..

  7. Formation of Microelement Composition and Hydrogeochemical Anomalous Zones of Ground-water of the Kama PreUrals Region

    Directory of Open Access Journals (Sweden)

    I. S. Kopylov

    2014-09-01

    Full Text Available The results of hydrogeochemical studies and groundwater mapping in the Kama PreUrals are given in the article. Analytical data (more than 2000 spectral analyses of water samples, mainly from the springs are analyzed. Regularities of distribution of the background values of basic geochemical parameters (macro – and microelements in groundwater has been studied. Hydrogeochemical particularities are revealed. Hydro-geochemical zoning was conducted and the geochemical anomalous zones were deter-mined. Studies provided for the first time an integrated assessment of microelements hydrogeochemistry of the Western Urals and the PreUrals at the regional level. A large number of hydrogeochemical anomalies are located on the territory of the Perm region. It was established that concentration for 18 elements exceeds a legislation admissible limit. The large anomalous zones are characteristic for high concentrations of Br, B, Ba, Mn, and Ti, but anomalies of Sb, Be, Cd, V, Cr, Ni, Pb, Sr, F, Zn, Co, Mo, and P are observed locally. Anomalies in the zone of active water exchange form 14 complex geochemical anomalous zones of areas from 2 000 up to 9 000 km2. The natural environments of formation of hydrogeochemical fields are the main factors of generation of the geochemical anomalies with predominant role of structural, tectonic conditions, and geodynamic (neotectonic activity. The major hydrogeochemical anomalies spatially coincide with litho-geochemical, geophysical anomalies, and geodynamic active zones.

  8. The compositionally zoned eruption of 1912 in the Valley of Ten Thousand Smokes, Katmai National Park, Alaska

    Science.gov (United States)

    Hildreth, Wes

    1983-10-01

    andesite. The zoning ranges of phenocrysts in the rhyolitic and intermediate ejecta do not overlap. New chemical data show the bulk SiO 2 range to be: rhyolite 77 ± 0.6, dacite 66-64.5, and andesite 61.5-58.5%. The dacitic and andesitic ejecta contrast in color and density, and it is not certain whether they form a compositional continuum. Analyses reported by Fenner within the 66-76% SiO 2 range were of banded pumice and lava and of bulk tephra that mechanically fractionated and mixed during flight. Despite the gap of 10% SiO 2, Fe-Ti-oxide temperatures show a continuous range from rhyolite (805-850°C) through dacite (855-955°C) to andesite (955-990°C). Thermal continuity and isotopic and trace-element data suggest that all were derived from a single magmatic system, whether or not they were physically contiguous before eruption. If the rhyolitic liquid separated from dacitic magma, extraction was so efficient that no dacitic phenocrysts were retained and no bulk compositions in the range 66-76% SiO 2 were created; if it were a partial melt of roof rocks atop an intermediate magma body, then such rocks had no O- or Sr-isotopic contrast with the andesite-dacite magma and clearly did not include the Jurassic arkosic or granitic basement. The presence of Holocene domes of pre-1912 glassy dacite adjacent to the 1912 vent suggest that the 7 km 3 (or more) of high-silica rhyolitic magma (a composition rare in the Aleutian arc) was generated in less than a few thousand years. The 1912 vent is semi-encircled by several andesitic stratocones and is as close to Mageik, Trident, and Griggs volcanoes as it is to Mt. Katmai. The erupted magma probably occupied only shallow levels of an extensive system of injection and storage under a cluster of several stratovolcanoes. Although Quaternary basalt is not known to have erupted here, the intrusion of basaltic magma probably sustains the greater-VTTS magmatic system.

  9. Sulfide intrusion and detoxification in Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2014-01-01

    nutrition in general. By a global review of sulfide intrusion, coupled with a series of field studies and in situ experiments we elucidate sulfide intrusion and different strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis...... indicating a possible role of sulfide in the sulfur nutrition beside the detoxification function. Our results suggest different adaptations of Z. marina to reduced sediments and sulfide intrusion ranging from bacterial and chemical reoxidation of sulfide to sulfate to incorporation of sulfide into organic...

  10. A novel method for improving cerussite sulfidization

    Institute of Scientific and Technical Information of China (English)

    Qi-cheng Feng; Shu-ming Wen; Wen-juan Zhao; Qin-bo Cao; Chao L

    2016-01-01

    Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sul-fide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

  11. Prevention of sulfide oxidation in sulfide-rich waste rock

    Science.gov (United States)

    Nyström, Elsa; Alakangas, Lena

    2015-04-01

    The ability to reduce sulfide oxidation in waste rock after mine closure is a widely researched area, but to reduce and/or inhibit the oxidation during operation is less common. Sulfide-rich (ca 30 % sulfur) waste rock, partially oxidized, was leached during unsaturated laboratory condition. Trace elements such as As and Sb were relatively high in the waste rock while other sulfide-associated elements such as Cu, Pb and Zn were low compared to common sulfide-rich waste rock. Leaching of unsaturated waste rock lowered the pH, from around six down to two, resulting in continuously increasing element concentrations during the leaching period of 272 days. The concentrations of As (65 mg/L), Cu (6.9 mg/L), Sb (1.2 mg/L), Zn (149 mg/L) and S (43 g/L) were strongly elevated at the end of the leaching period. Different alkaline industrial residues such as slag, lime kiln dust and cement kiln dust were added as solid or as liquid to the waste rock in an attempt to inhibit sulfide oxidation through neo-formed phases on sulfide surfaces in order to decrease the mobility of metals and metalloids over longer time scale. This will result in a lower cost and efforts of measures after mine closure. Results from the experiments will be presented.

  12. Investigation of chemical suppressants for inactivation of sulfide ores

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to investigate the effective control method of spontaneous combustion in the mining of sulfide ore deposits, This paper presents the testing results of several selected chemicals (water glass, calcium chloride, calcium oxide, magnesium oxide and their composites) as oxidation suppressants for sulfide ores. A weight increment scaling method was used to measure suppressant performance, and this method proved to be accurate, simple and convenient. Based on a large number of experiments, the test results show that four types of chemical mixtures demonstrate a good performance in reducing the oxidation rate of seven active sulfide ore samples by up to 27% to 100% during an initial 76 d period. The mixtures of water glass mixed with calcium chloride and magnesium oxide mixed with calcium chloride can also act as fire suppressants when used with fire sprinkling systems.

  13. Mechanochemical reduction of copper sulfide

    DEFF Research Database (Denmark)

    Balaz, P.; Takacs, L.; Jiang, Jianzhong

    2002-01-01

    The mechanochemical reduction of copper sulfide with iron was induced in a Fritsch P-6 planetary mill, using WC vial filled with argon and WC balls. Samples milled for specific intervals were analyzed by XRD and Mossbauer spectroscopy. Most of the reaction takes place during the first 10 min...... of milling and only FeS and Cu are found after 60 min. The main chemical process is accompanied by phase transformations of the sulfide phases as a result of milling. Djurleite partially transformed to chalcocite and a tetragonal copper sulfide phase before reduction. The cubic modification of FeS was formed...... first, transforming to hexagonal during the later stages of the process. The formation of off-stoichiometric phases and the release of some elemental sulfur by copper sulfide are also probable....

  14. Hydrogen sulfide in signaling pathways.

    Science.gov (United States)

    Olas, Beata

    2015-01-15

    For a long time hydrogen sulfide (H₂S) was considered a toxic compound, but recently H₂S (at low concentrations) has been found to play an important function in physiological processes. Hydrogen sulfide, like other well-known compounds - nitric oxide (NO) and carbon monoxide (CO) is a gaseous intracellular signal transducer. It regulates the cell cycle, apoptosis and the oxidative stress. Moreover, its functions include neuromodulation, regulation of cardiovascular system and inflammation. In this review, I focus on the metabolism of hydrogen sulfide (including enzymatic pathways of H₂S synthesis from l- and d-cysteine) and its signaling pathways in the cardiovascular system and the nervous system. I also describe how hydrogen sulfide may be used as therapeutic agent, i.e. in the cardiovascular diseases.

  15. Electrical Resistivity Correlation to Vadose Zone Sediment and Pore-Water Composition for the BC Cribs and Trenches Area

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey; Ward, Anderson L.; Um, Wooyong; Bjornstad, Bruce N.; Rucker, Dale F.; Lanigan, David C.; Benecke, Mark W.

    2009-06-01

    This technical report documents the results of geochemical and soil resistivity characterization of sediment obtained from four boreholes drilled in the BC Cribs and Trench area. Vadose zone sediment samples were obtained at a frequency of about every 2.5 ft from approximately 5 ft bgs to borehole total depth. In total, 505 grab samples and 39 six-inch long cores were obtained for characterization. The pore-water chemical composition data, laboratory-scale soil resistivity and other ancillary physical and hydrologic measurements and analyses described in this report are designed to provide a crucial link between direct measurements on sediments and the surface-based electrical-resistivity information obtained via field surveys. A second goal of the sediment characterization was to measure the total and water-leachable concentrations of key contaminants of concern as a function of depth and distance from the footprints of inactive disposal facilities. The total and water-leachable concentrations of key contaminants will be used to update contaminant distribution conceptual models and to provide more data for improving base-line risk predictions and remedial alternative selections. The ERC “ground truthing” exercise for the individual boreholes showed mixed results. In general, the high concentrations of dissolved salts in the pore waters of sediments from C5923, C5924 and C4191 produced a low resistivity “target” in the processed resistivity field surveys, and variability could be seen in the resistivity data that could relate to the variability in pore- water concentrations but the correlations (regression R2 were mediocre ranging from 0.2 to 0.7 at best; where perfect correlation is 1.0). The field-based geophysical data also seemed to suffer from a sort of vertigo, where looking down from the ground surface, the target (e.g., maximum pore-water salt concentration) depth was difficult to resolve. The best correlations between the field electrical

  16. Chemical and sulphur isotope compositions of pyrite in the Jaduguda U (-Cu-Fe) deposit, Singhbhum shear zone, eastern India: Implications for sulphide mineralization

    Science.gov (United States)

    Pal, Dipak C.; Sarkar, Surajit; Mishra, Biswajit; Sarangi, A. K.

    2011-06-01

    The Jaduguda U (-Cu-Fe) deposit in the Singhbhum shear zone has been the most productive uranium deposit in India. Pyrite occurs as disseminated grains or in sulphide stringers and veins in the ore zone. Veins, both concordant and discordant to the pervasive foliation, are mineralogically either simple comprising pyrite ± chalcopyrite or complex comprising pyrite + chalcopyrite + pentlandite + millerite. Nickel-sulphide minerals, though fairly common in concordant veins, are very rare in the discordant veins. Pyrite in Ni-sulphide association is commonly replaced by pentlandite at the grain boundary or along micro-cracks. Based on concentrations of Co and Ni, pyrite is classified as: type-A - high Co (up to 30800 ppm), no/low Ni; type-B - moderate Co (up to 16500 ppm) and moderate to high Ni (up to 32700 ppm); type-C - no/low Co and high Ni (up to 43000 ppm); type-D - neither Co nor Ni. Textural and compositional data of pyrites suggest that the hydrothermal fluid responsible for pre-/early-shearing mineralization evolved from Co-rich to Ni-rich and the late-/post-shearing fluid was largely depleted in minor elements. Sulphur isotope compositions of pyrite mostly furnish positive values ranging between -0.33 and 12.06‰. Composite samples of pyrites with only type-A compositions and mixed samples of type-A and type-B are consistently positive. However, pyrite with mixed type-A and type-C and pyrite with type-D compositions have negative values but close to 0‰. By integrating minor element and sulphur isotope compositions of pyrite in conjunction with other published data on the Jaduguda deposit, it is proposed that reduced sulphur for the precipitation of most pyrites (type-A, type-B) was likely derived from isotopically heavy modified seawater. However, some later sulphur might be magmatic in origin remobilized from existing sulphides in the mafic volcanic rocks in the shear zone.

  17. Chemical and sulphur isotope compositions of pyrite in the Jaduguda U (–Cu–Fe) deposit, Singhbhum shear zone, eastern India: Implications for sulphide mineralization

    Indian Academy of Sciences (India)

    Dipak C Pal; Surajit Sarkar; Biswajit Mishra; A K Sarangi

    2011-06-01

    The Jaduguda U (–Cu–Fe) deposit in the Singhbhum shear zone has been the most productive uranium deposit in India. Pyrite occurs as disseminated grains or in sulphide stringers and veins in the ore zone. Veins, both concordant and discordant to the pervasive foliation, are mineralogically either simple comprising pyrite ± chalcopyrite or complex comprising pyrite + chalcopyrite + pentlandite + millerite. Nickel-sulphide minerals, though fairly common in concordant veins, are very rare in the discordant veins. Pyrite in Ni-sulphide association is commonly replaced by pentlandite at the grain boundary or along micro-cracks. Based on concentrations of Co and Ni, pyrite is classified as: type-A — high Co (up to 30800 ppm), no/low Ni; type-B — moderate Co (up to 16500 ppm) and moderate to high Ni (up to 32700 ppm); type-C — no/low Co and high Ni (up to 43000 ppm); type-D — neither Co nor Ni. Textural and compositional data of pyrites suggest that the hydrothermal fluid responsible for pre-/early-shearing mineralization evolved from Co-rich to Ni-rich and the late-/post-shearing fluid was largely depleted in minor elements. Sulphur isotope compositions of pyrite mostly furnish positive values ranging between -0.33 and 12.06%. Composite samples of pyrites with only type-A compositions and mixed samples of type-A and type-B are consistently positive. However, pyrite with mixed type-A and type-C and pyrite with type-D compositions have negative values but close to 0. By integrating minor element and sulphur isotope compositions of pyrite in conjunction with other published data on the Jaduguda deposit, it is proposed that reduced sulphur for the precipitation of most pyrites (type-A, type-B) was likely derived from isotopically heavy modified seawater. However, some later sulphur might be magmatic in origin remobilized from existing sulphides in the mafic volcanic rocks in the shear zone.

  18. Compositional diversity of near-, far-side transitory zone around Naonobu, Webb and Sinus Successus craters: Inferences from Chandrayaan-1 Moon Mineralogy Mapper (M3) data

    Indian Academy of Sciences (India)

    Rishikesh Bharti; D Ramakrishnan; K D Singh

    2014-02-01

    This study investigated the potential of Moon Mineralogy Mapper (M3) data for studying compositional variation in the near-, far-side transition zone of the lunar surface. For this purpose, the radiance values of the M3 data were corrected for illumination and emission related effects and converted to apparent reflectance. Dimensionality of the calibrated reflectance image cube was reduced using Independent Component Analysis (ICA) and endmembers were extracted by using Pixel Purity Index (PPI) algorithm. The selected endmembers were linearly unmixed and resolved for mineralogy using United States Geological Survey (USGS) library spectra of minerals. These mineralogically resolved endmembers were used to map the compositional variability within, and outside craters using Spectral Angle Mapper (SAM) algorithm. Cross validation for certain litho types was attempted using band ratios like Optical Maturity (OMAT), Color Ratio Composite and Integrated Band Depth ratio (IBD). The identified lithologies for highland and basin areas match well with published works and strongly support depth related magmatic differentiation. Prevalence of pigeonite-basalt, pigeonite-norite and pyroxenite in crater peaks and floors are unique to the investigated area and are attributed to local, lateral compositional variability in magma composition due to pressure, temperature, and rate of cooling.

  19. Revisiting the Numerical Convergence of Cohesive-Zone Models in Simulating the Delamination of Composite Adhesive Joints by Using the Finite-Element Analysis

    Science.gov (United States)

    Liu, P. F.; Gu, Z. P.; Hu, Z. H.

    2016-11-01

    Delamination is the dominating failure mechanism in composite adhesive joints. A deep insight into the delamination failure mechanism requires advanced numerical methods. Currently, cohesive-zone models (CZMs), in combination with the finite-element analysis (FEA), have become powerful tools for modeling the initiation and growth of delaminations in composites. However, ensuring the numerical convergence in the CZMs used for a delamination analysis of three-dimensional (3D) composite structures is always a challenging issue due to the "snap-back" instability in the nonlinear implicit FEA, which arises mainly from the cohesive softening behavior. Based on the midplane interpolation technique, first numerical techniques for implementing 3D bilinear and exponential CZMs by using ABAQUS-UEL (user element subroutine) are developed in this paper. In particular, a viscous regularization by introducing the damping effect into the stiffness equation is used to improve the convergence. Two examples, a single-lap composite joint and a composite skin/stiffener panel under tension, demonstrate the numerical technique developed. Then, the effect of cohesion parameters on the numerical convergence based on the viscous regularization is studied.

  20. Oxidation sulfidation resistance of Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, Ken (Naperville, IL); Baxter, David J. (Woodridge, IL)

    1984-01-01

    High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1-8 wt. % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500.degree.-1000.degree. C.

  1. Evolution of the habitable zone of low-mass stars. Detailed stellar models and analytical relationships for different masses and chemical compositions

    CERN Document Server

    Valle, G; Moroni, P G Prada; Degl'Innocenti, S

    2014-01-01

    We study the temporal evolution of the habitable zone (HZ) of low-mass stars - only due to stellar evolution - and evaluate the related uncertainties. These uncertainties are then compared with those due to the adoption of different climate models. We computed stellar evolutionary tracks from the pre-main sequence phase to the helium flash at the red-giant branch tip for stars with masses in the range [0.70 - 1.10] Msun, metallicity Z in the range [0.005 - 0.04], and various initial helium contents. We evaluated several characteristics of the HZ, such as the distance from the host star at which the habitability is longest, the duration of this habitability, the width of the zone for which the habitability lasts one half of the maximum, and the boundaries of the continuously habitable zone (CHZ) for which the habitability lasts at least 4 Gyr. We developed analytical models, accurate to the percent level or lower, which allowed to obtain these characteristics in dependence on the mass and the chemical composit...

  2. Seasonal variability in particulate matter source and composition to the depositional zone of Baltimore Canyon, U.S. Mid-Atlantic Bight

    Science.gov (United States)

    Prouty, Nancy G.; Mienis, Furu; Campbell, P.; Roark, E. Brendan; Davies, Andrew; Robertson, Craig M.; Duineveld, Gerard; Ross, Steve W.; Rhodes, M.; Demopoulos, Amanda W.J.

    2017-01-01

    Submarine canyons are often hotspots of biomass and productivity in the deep sea. However, the majority of deep-sea canyons remain poorly sampled. Using a multi-tracer approach, results from a detailed geochemical investigation from a year-long sediment trap deployment reveals details concerning the source, transport, and fate of particulate matter to the depositional zone (1318 m) of Baltimore Canyon on the US Mid-Atlantic Bight (MAB). Both organic biomarker composition (sterol and n-alkanes) and bulk characteristics (δ13C, Δ14C, Chl-a) suggest that on an annual basis particulate matter from marine and terrestrially-derived organic matter are equally important. However, elevated Chlorophyll-a and sterol concentrations during the spring sampling period highlight the seasonal influx of relatively fresh phytodetritus. In addition, the contemporaneous increase in the particle reactive elements cadmium (Cd) and molybdenum (Mo) in the spring suggest increased scavenging, aggregation, and sinking of biomass during seasonal blooms in response to enhanced surface production within the nutricline. While internal waves within the canyon resuspend sediment between 200 and 600 m, creating a nepheloid layer rich in lithogenic material, near-bed sediment remobilization in the canyon depositional zone is minimal. Instead, vertical transport and lateral transport across the continental margin are the dominant processes driving seasonal input of particulate matter. In turn, seasonal variability in deposited particulate organic matter may be linked to benthic faunal composition and ecosystem scale carbon cycling.

  3. Variation in phytoplankton composition between two North Pacific frontal zones along 158°W during winter-spring 2008-2011

    Science.gov (United States)

    Howell, Evan A.; Bograd, Steven J.; Hoover, Aimee L.; Seki, Michael P.; Polovina, Jeffrey J.

    2017-01-01

    Data from three research cruises along the 158°W meridian through the North Pacific Subtropical Frontal Zone (STF) during spring 2008, 2009, and 2011 were used to estimate phytoplankton functional types and size classes. These groups were used to describe phytoplankton composition at the North Pacific Subtropical (STF) and Transition Zone Chlorophyll (TZCF) Fronts, which represent ecologically important large-scale features in the central North Pacific. Phytoplankton class composition was consistent at each front through time, yet significantly different between fronts. The STF contained lower integrated chlorophyll-a concentrations, with surface waters dominated by picophytoplankton and a deep chlorophyll maximum equally comprised of pico- and nanophytoplankton. The TZCF contained significantly higher concentrations of nanophytoplankton through the water column, specifically the prymnesiophyte group. Integrated chlorophyll-a concentrations at the TZCF were 30-90% higher than at the STF, with the dominant increase in the signal from the nanophytoplanktonic prymnesiophyte group. The meridional position of the STF was consistently located near 32°N through these three years, with the more spatially variable TZCF ranging from 2° to 4° further north of the STF. This variability in the frontal position of the TZCF may lead to ecological impacts though the food web. Continued in-situ and remote monitoring, specifically during El Niño and ENSO neutral phases, will provide additional ecological information to help understand mechanistic causes of phytoplankton variability in this important ecological region.

  4. A novel biological approach on extracellular synthesis and characterization of semiconductor zinc sulfide nanoparticles

    Science.gov (United States)

    Malarkodi, Chelladurai; Annadurai, Gurusamy

    2013-10-01

    The expansion of reliable and eco-friendly process for synthesis of semiconductor nanoparticle is an important step in the emerging field of biomedical nanotechnology. In this communication, the zinc sulfide nanoparticles were biologically synthesized by using Serratia nematodiphila which was isolated from chemical company effluent. The surface plasmon resonance centered at 390 nm on the UV spectrum indicates the presence of zinc sulfide nanoparticles in the reaction mixture ( S. nematodiphila and zinc sulfate); EDAX analysis also confirmed the presence of zinc sulfide nanoparticles. Scanning electron microscope image showed that the synthesized zinc sulfide nanoparticles were spherical in nature and nanoparticles of about 80 nm in size were obtained from transmission electron microscope images. The peaks in the XRD spectrum corresponding to (111), (220) and (311) show that the zinc sulfide nanoparticles are crystalline in nature. Fourier transforms infrared spectroscopy shows the functional groups of the nanoparticle in the range of 4,000-400 cm-1. Further, the antibacterial activity of zinc sulfide nanoparticles was examined against Bacillus subtilis and Klebsiella planticola. The maximum zone of inhibition occurred at 200 μl of silver nanoparticles. Due to potent antimicrobial and intrinsic properties of zinc sulfide, it is actively used for biomedical and food packaging applications.

  5. Compositional variations in spinel-hosted pargasite inclusions in the olivine-rich rock from the oceanic crust-mantle boundary zone

    Science.gov (United States)

    Tamura, Akihiro; Morishita, Tomoaki; Ishimaru, Satoko; Hara, Kaori; Sanfilippo, Alessio; Arai, Shoji

    2016-05-01

    The crust-mantle boundary zone of the oceanic lithosphere is composed mainly of olivine-rich rocks represented by dunite and troctolite. However, we still do not fully understand the global variations in the boundary zone, and an effective classification of the boundary rocks, in terms of their petrographical features and origin, is an essential step in achieving such an understanding. In this paper, to highlight variations in olivine-rich rocks from the crust-mantle boundary, we describe the compositional variations in spinel-hosted hydrous silicate mineral inclusions in rock samples from the ocean floor near a mid-ocean ridge and trench. Pargasite is the dominant mineral among the inclusions, and all of them are exceptionally rich in incompatible elements. The host spinel grains are considered to be products of melt-peridotite reactions, because their origin cannot be ascribed to simple fractional crystallization of a melt. Trace-element compositions of pargasite inclusions are characteristically different between olivine-rich rock samples, in terms of the degree of Eu and Zr anomalies in the trace-element pattern. When considering the nature of the reaction that produced the inclusion-hosting spinel, the compositional differences between samples were found to reflect a diversity in the origin of the olivine-rich rocks, as for example in whether or not a reaction was accompanied by the fractional crystallization of plagioclase. The differences also reflect the fact that the melt flow system (porous or focused flow) controlled the melt/rock ratios during reaction. The pargasite inclusions provide useful data for constraining the history and origin of the olivine-rich rocks and therefore assist in our understanding of the crust-mantle boundary of the oceanic lithosphere.

  6. Calculation of sulfide capacities of multicomponent slags

    Science.gov (United States)

    Pelton, Arthur D.; Eriksson, Gunnar; Romero-Serrano, Antonio

    1993-10-01

    The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A12O3 and TiO2 as components. The model has been extended to calculate a priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO2-Al2O3-TiO2-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria.

  7. Preliminary investigation of the nature and origin of the Sierra Mojada Non-sulfide Zn deposits, Coahuila, Mexico

    Science.gov (United States)

    Ahn, H.; Kyle, J.; Gilg, H.; Kolvoord, R.

    2009-05-01

    The Sierra Mojada district consists of multiple types of mineral concentrations ranging from polymetallic sulfide deposits, 'non-sulfide Zn' deposits (separate smithsonite and hemimorphite zones), and a Pb carbonate manto hosted by Upper Jurassic to Lower Cretaceous carbonates. The district is typically grouped with other polymetallic carbonate replacement deposits of southwestern North America, but the intrusive rocks that commonly are associated with these types of deposits are not known at Sierra Mojada. The Sierra Mojada district located near the boundary of the Coahuila Platform and the Sabinas Basin that formed during Late Jurassic and Cretaceous tectonic extension. The east-trending San Marcos fault runs through the Sierra Mojada district and is thought to have acted as the major conduit for basinal fluids, responsible for local dolomitization, sulfide mineralization, and petroleum in the region. The polymetallic sulfides are the stratigraphically and structurally highest ore zone and occur north of the San Marcos fault. Non-sulfide Zn (hemimorphite, smithsonite and sauconite) and lead (cerussite) concentrations occur south of the fault in the Aurora and La Pena Formations. The Iron Oxide Manto consists of stratabound zones of dominantly of hemimorphite pore-filling in Fe-oxide rich dolostones giving the ore a distinct red to orange color. The Smithsonite Manto has distinct karst features, including internal sediments interbanded with smithsonite in the lower part of the orebody. The non-sulfide Zn ores are being studied to document their morphologies, growth patterns, and paragenetic relationships using conventional petrography, SEM, and CL-based ESEM. In the Smithsonite Manto, banded and colloform smithsonite consists of aggregates of rhombohedral crystals that grew into open space and also occurs within internal sediment bands with hemimorphite or Zn clays and Zn oxides. Black dendrites of Mn oxides with Fe oxides are encased in banded smithsonite

  8. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH, β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group. β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  9. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    PENG LingLing; ZHANG Xiu; MA Jie; ZHONG ZhenZhen; ZHANG Zhe; ZHANG Yan; WANG JianBo

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH.,β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group.β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  10. Sulfide capacities of Na2O-SiO2 melts

    Science.gov (United States)

    Reddy, R. G.; Zhao, W.

    1995-10-01

    Sulfide capacities of Na2O-SiO2 melts at 1473, 1523, 1573, 1623, and 1673 K were calculated a priori using the revised Reddy Blander model. An expression for C S in the composition range of 0≤ X SiO 2sulfide capacities of slags are found to be directly related to two independent quantities: the equilibrium constant K and the activity of the base oxide.

  11. Microstructure of reaction zone in WCp/duplex stainless steels matrix composites processing by laser melt injection

    NARCIS (Netherlands)

    Do Nascimento, A. M.; Ocelik, V.; Ierardi, M. C. F.; De Hosson, J. Th. M.

    2008-01-01

    The laser melt injection (LMI) process has been used to create a metal matrix composite consisting of 80gm sized multi-grain WC particles embedded in three cast duplex stainless steels. The microstruture was investigated by scanning electron microscopy with integrated EDS and electron back-scatter d

  12. Nanostructured metal sulfides for energy storage.

    Science.gov (United States)

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-07

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

  13. Influence of arsenic on iron sulfide transformations

    NARCIS (Netherlands)

    Wolthers, M.; Butler, I.B.; Rickard, D.

    2007-01-01

    The association of arsenate, As(V), and arsenite, As(III), with disordered mackinawite, FeS, was studied in sulfide-limited (Fe:S = 1:1) and excess-sulfide (Fe:S = 1:2) batch experiments. In the absence of arsenic, the sulfide-limited experiments produce disordered mackinawite while the

  14. Replacive sulfide formation in anhydrite chimneys from the Pacmanus hydrothermal field, Papua New Guinea

    Science.gov (United States)

    Los, Catharina; Bach, Wolfgang; Plümper, Oliver

    2016-04-01

    Hydrothermal flow within the oceanic crust is an important process for the exchange of energy and mass between the lithosphere, hydrosphere and biosphere. Infiltrated seawater heats up and interacts with wall rock, causing mineral replacement reactions. These play a large role in the formation of ore deposits; at the discharge zone, a hot, acidic and metal-rich potential ore fluid exits the crust. It mixes with seawater and forms chimneys, built up of sulfate minerals such as anhydrite (CaSO4), which are subsequently replaced by sulfide minerals. Sulfide formation is related to fluid pathways, defined by cracks and pores in the sulfate chimney. Over time, these systems might develop into massive sulfide deposits. The big question is then: how is sulfate-sulfide replacement related to the evolution of rock porosity? To address this question, sulfide-bearing anhydrite chimneys from the Pacmanus hydrothermal field (Manus Basin, Papua New Guinea) were studied using X-ray tomography, EMPA, FIB-SEM and -TEM. The apparently massive anhydrite turns out highly porous on the micro scale, with sulfide minerals in anhydrite cleavage planes and along grain boundaries. The size of the sulfide grains relates to the pores they grew into, suggesting a tight coupling between dissolution (porosity generation) and growth of replacive minerals. Some of the sulfide grains are hollow and apparently used the dissolving anhydrite as a substrate to start growth in a pore. Another mode of sulfide development is aggregates of euhedral pyrite cores surrounded by colloform chalcopyrite. This occurrence implies that fluid pathways have remained open for some time to allow several stages of precipitation during fluid evolution. To start the replacement and to keep it going, porosity generation is crucial. Our samples show that dissolution of anhydrite occurred along pathways where fluid could enter, such as cleavage planes and grain boundaries. It appears that fluids ascending within the inner

  15. The Voisey's Bay Ni-Cu-Co Sulfide Deposit,Labrador,Canada:Emplacement of Silicate and Sulfide-Laden Magmas into Spaces Created within a Structural Corridor%The Voisey's Bay Ni-Cu-Co Sulfide Deposit,Labrador, Canada: Emplacement of Silicate and Sulfide-Laden Magmas into Spaces Created within a Structural Corridor

    Institute of Scientific and Technical Information of China (English)

    Peter C.Lightfoot; Dawn Evans-Lamswood; Robert Wheeler

    2012-01-01

    Abstract:The Voisey's Bay Ni-Cu-Co sulfide deposit is hosted in a 1.34 Ga mafic intrusion that is part of the Nain Plutonic Suite in Labrador,Canada.The Ni-Cu-Co sulfide mineralization is associated with magmatic breccias that are typically contained in weakly mineralized olivine gabbros,troctolites and ferrogabbros,but also occur as veins in adjacent paragneiss.The mineralization is associated with a dyke-like body which is termed the feeder dyke.This dyke connects the shallow differentiated Eastern Deeps chamber in the east to a deeper intrusion in the west termed the Western Deeps Intrusion.Where the conduit is connected to the Eastern Deeps Intrusion,the Eastern Deeps Deposit is developed at the entry line of the dyke along the steep north wall of the Eastern Deeps Intrusion.The Eastern Deeps Deposit is surrounded by a halo of moderately to weakly mineralized Variable-Textured Troctolite (VTT) that reaches a maximum thickness above the ENE-WSW axis of the Eastern Deeps Deposit.At depth to the west,the conduit is adjacent to the south side of the Western Deeps Intrusion,where the dyke and intrusion contain disseminated magmatic sulfide mineralization.The Reid Brook Zone plunges to the east within the dyke,and both the dyke and adjacent paragneiss are mineralized.The Ovoid Deposit comprises a bowl-shaped body of massive sulfide where the dyke widens near to the present-day surface.It is not clear whether this deposit was developed as a widened-zone within the conduit or at the entry point into a chamber that is now lost to erosion.The massive sulfides and breccia sulfides of the Eastern Deeps are petrologically and chemically different when compared to the disseminated sulfides in the VTT; there is a marked break in Ni tenor (Ni content in 100% sulfide,abbreviated to [Ni] 100) and Ni/Co of sulfide between the two.The boundary of the sulfide types is often marked by strong sub-horizontal alignment of heavily digested and metamorphosed paragneiss fragments

  16. Experimental constraints on gold and silver solubility in iron sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Pal' yanova, Galina [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation); Mikhlin, Yuri [Institute of Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Kokh, Konstantin, E-mail: k.a.kokh@gmail.com [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation); Siberian Physical–Technical Institute of Tomsk State University, 1, Novosobornaya, Tomsk, 634050 (Russian Federation); Karmanov, Nick [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Seryotkin, Yurii [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation)

    2015-11-15

    Experiments were performed to determine crystallization of Fe,S-melts (pyriti≿ and troilitic with molar ratio S/Fe ratios of 2 and 1, respectively) containing traces of gold and silver at (Ag/Au){sub wt} ratios varying from 10 to 0.1. The solid products were studied by optical microscopy, scanning electron microscopy, X-ray powder diffraction (XRD), microprobe analysis, and X-ray photoelectron spectroscopy (XPS) in order to reveal the concentration limits of “invisible” gold and silver in magmatic iron sulfides, and to determine the influence of sulfur on forms of precious metals in the Fe–S system with different Ag/Au ratios. Au–Ag phases do not form inclusions but instead concentrate on the grain boundaries in the synthetic pyrrhotite and troilite, while pyrite comprises micro- (1–5 μm) and macroinclusions of Au–Ag alloys and Au–Ag sulfides. In “pyriti≿” systems, the fineness of alloys increases from 650 to 970‰ and the composition of sulfides changes from acanthite (Ag{sub 2}S) to uytenbogaardtite (Ag{sub 3}AuS{sub 2}) and petrovskaite (AgAuS) as the Ag/Au ratio decreases. The concentrations of “invisible” precious metals revealed in troilite were 0.040 ± 0.013 wt.% Au and 0.079 ± 0.016 wt.% Ag. Measured concentrations in pyrite and pyrrhotite were <0.024 wt.% Au and <0.030 wt.% Ag. The surface layers of iron sulfides probed with XPS were enriched in the precious metals, and in silver relative to gold, especially in the systems with Fe/S = 1, probably, due to depletion of the metallic alloy surfaces with gold. Au- and Ag-bearing iron sulfides crystallized primarily from melts may be the source of redeposited phases in hydrothermal and hypergene processes. - Highlights: • The samples of Fe–S–Au–Ag system were synthesized. • Coupled solubility of gold and silver in iron sulfides was specified. • Ag–Au inclusions on surfaces of iron sulfides are likely to be enriched in silver. • Au–Ag sulfides can exist along with

  17. Regularities in changes of chemical composition of waters from the tenth zone of Bibieibat field during the development period

    Energy Technology Data Exchange (ETDEWEB)

    Markarova, O.A.

    1967-01-01

    While the tenth zone of Bibieibat oilfield was being flooded with seawater, advance of the flood front was determined by mineral analysis of produced water from several wells. Connate water had considerably greater mineral content than the injected seawater. Chloride content of produced water was determined before and during injection of seawater, and from these data the distribution of floodwater in the field is shown in 3 maps. The data show that floodwater did not advance uniformly everywhere. In most areas floodwater advanced at rates of 2 to 25 m per month; in some places advances of 40 m per month were found. Such nonuniformity in rates is caused by unequal pressure drops from place to place and by rock heterogeneity.

  18. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    Directory of Open Access Journals (Sweden)

    Xuejun Dong

    2016-05-01

    Full Text Available High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm

  19. Community Composition of Nitrous Oxide Consuming Bacteria in the Oxygen Minimum Zone of the Eastern Tropical South Pacific

    Directory of Open Access Journals (Sweden)

    Xin Sun

    2017-06-01

    Full Text Available The ozone-depleting and greenhouse gas, nitrous oxide (N2O, is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA and transcriptionally active (RNA nitrous oxide reductase (nosZ genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments. In addition to nosZ genes related to those of known marine denitrifiers, atypical nosZ genes, related to those of soil bacteria that do not possess a complete denitrification pathway, were also detected, especially in surface waters. The community composition of the total nosZ assemblage was significantly different from the active assemblage. The community composition of the total nosZ assemblage was significantly different between coastal and off-shore stations. The low oxygen assemblages from both stations were similar to each other, while the higher oxygen assemblages were more variable. Community composition of the active nosZ assemblage was also significantly different between stations, and varied with N2O concentration but not O2. Notably, nosZ assemblages were not only present but also active in oxygenated seawater: the abundance of total and active nosZ bacteria from oxygenated surface water (indicated by nosZ gene copy number was similar to or even larger than in anoxic waters, implying the potential for N2O consumption even in the oxygenated surface water.

  20. Hydrolysis of Carbonyl Sulfide in Binary Mixture of Diethylene Glycol Diethyl Ether and Water

    Institute of Scientific and Technical Information of China (English)

    李新学; 刘迎新; 魏雄辉

    2005-01-01

    The solubility and hydrolysis of carbonyl sulfide in binary mixture of diethylene glycol diethyl ether and water are studied as a function of composition. The use of an aqueous solution of diethylene glycol diethyl ether enhances the solubility and hydrolysis rate of carbonyl sulfide compared with that in pure water. The composition of the mixture with maximum hydrolysis rate varies with temperature. The thermophysical properties including density, viscosity, and surface tension as a function of composition at 20℃ under atmospheric pressure as well as liquid-liquid equilibrium (LLE) data over the temperature range from 28℃ to 90℃ are also measured for the binary mixture.

  1. Quantitative comparison of the water permeable zone among four types of dental adhesives used with a dual-cured composite.

    Science.gov (United States)

    Chang, Juhea; Platt, Jeffrey A; Yi, Keewook; Cochran, Michael A

    2006-01-01

    This study compared silver penetration in the adhesive interface among four versions of adhesives from the same manufacturer: OptiBond FL, OptiBond Solo Plus, OptiBond Solo Plus Dual Cure, and OptiBond Solo Plus Self-Etch, when coupled with dual-cured composite, CoreRestore 2 (Kerr). Twenty flat dentin surfaces were prepared using one of the adhesives and bonded with the composite, following the manufacturer's instructions. The surfaces were sectioned into 2-mm slabs and immersed in ammoniacal silver nitrate for 24 hours. Each specimen was exposed to a photodeveloping solution for eight hours and examined with a scanning electron microscope (SEM). The water permeable area occupied by the silver nitrate tracer was determined, and the relative weight of silver was analyzed by wavelength dispersive spectrometry (WDS). The OptiBond FL group had a significantly lower silver content than the other groups (p < 0.0001). Each group demonstrated different patterns of silver deposition within the adhesive layer and within various features of artifactual fracture from dehydration stress of the SEM. This may be indicative of weak links in the bonded interfaces. Simplified-step adhesives showed increased permeability, which can lead to disruption of coupling with composites.

  2. Characterization of fruit products by capillary zone electrophoresis and liquid chromatography using the compositional profiles of polyphenols: application to authentication of natural extracts.

    Science.gov (United States)

    Navarro, Meritxell; Núñez, Oscar; Saurina, Javier; Hernández-Cassou, Santiago; Puignou, Lluis

    2014-02-01

    Capillary zone electrophoresis (CZE) and high performance liquid chromatography (HPLC) were applied to the authentication of fruit products based on the compositional profiles of polyphenols. Various sample treatments were used to maximize the overall recovery of polyphenols or specific fractions, such as phenolic acids or anthocyanins. The resulting CZE and HPLC data were treated with Principal Component Analysis (PCA) showing that samples were mainly clustered according to the fruit of origin, with cranberry- and grape-based products clearly separated in groups. A possible adulterated cranberry extract was analyzed more deeply by high resolution mass spectrometry (HRMS) in order to identify the presence of A-type proanthocyanidins, which are characteristic and more abundant in cranberry-based products. In accordance with PCA interpretation, HRMS results indicated that the suspicious sample was not a cranberry-based product, allowing us to validate and demonstrate the suitability of both CZE- and HPLC-proposed methods for the characterization of fruit-based products.

  3. Effect of surfactant species and electrophoretic medium composition on the electrophoretic behavior of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis.

    Science.gov (United States)

    Fukai, Nao; Kitagawa, Shinya; Ohtani, Hajime

    2017-07-01

    We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation. The order of the interaction between the polymers and the surfactants depended on both the surfactant species and the composition of the electrophoretic medium. Their investigation revealed that the separation is majorly affected by the hydrophobic interactions between the polymers and the ionic surfactants. In addition, the electrophoretic behavior of polycarbonate suggested that electrostatic interaction also affects the selectivity of the polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Luminescence in Sulfides: A Rich History and a Bright Future

    Directory of Open Access Journals (Sweden)

    Philippe F. Smet

    2010-04-01

    Full Text Available Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs. The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles.

  5. STUDY OF HYDROGEN SULFIDE REMOVAL FROM GROUNDWATER

    Directory of Open Access Journals (Sweden)

    T. Lupascu

    2013-06-01

    Full Text Available The process of the hydrogen sulfide removal from the underground water of the Hancesti town has been investigated. By oxygen bubbling through the water containing hydrogen sulfide, from the Hancesti well tube, sulfur is deposited in the porous structure of studied catalysts, which decreases their catalytic activity. Concomitantly, the process of adsorption / oxidation of hydrogen sulfide to sulfate take place. The kinetic research of the hydrogen sulfide removal from the Hancesti underground water, after its treatment by hydrogen peroxide, proves greater efficiency than in the case of modified carbonic adsorbents. As a result of used treatment, hydrogen sulfide is completely oxidized to sulfates

  6. Mantle Composition and Temperature of Western North America Revealed from Direct P and S Wave Velocities of KLB-1 Peridotite to the Condition of Transition Zone

    Science.gov (United States)

    Wang, X.; Chen, T.; Qi, X.; Zou, Y.; Liebermann, R. C.; Li, B.

    2015-12-01

    Comparing the elasticity of candidate compositional models with seismic profiles (e.g., PREM and AK135) is one of the most important geophysical approaches to constrain the mineralogical composition of the mantle. However in such averaging schemes (e.g., Voigt-Reuss-Hill), it is difficult to take into account all of the mineralogical and chemical complexities; we therefore undertook elasticity study of a natural mantle rock sample at high pressures and temperatures. In this study, a series of polycrystalline aggregates of peridotite KLB-1 (from Kilbourne Hole, New Mexico) were hot-pressed at pressures of 3-15 GPa and temperatures of 1200-1400°C. Scanning electron microscopy (SEM), Electron Microprobe Analysis (EPMA) and X-ray diffraction (XRD) were used to characterize the texture, grain size, and composition of these well-sintered specimens. For the first time in history, the P and S wave velocities of a pyrolitic multiphase aggregate were directly measured at mantle transition zone pressures and temperatures using ultrasonic interferometry. Based on the phase fractions from EPMA and the P and S wave velocities from in situ measurement at high pressure and high temperature, the velocities of the KLB-1 peridotite along 1200-1400 oC adiabatic mantle geotherms were obtained and compare well with the seismic models of western North America, the region where these peridotite KLB-1 samples were collected. The comparison with regional seismic models of western North America (e.g., GCA and TNA/TNA2) as well as global seismic models (PREM and AK135) place unprecedented constraints on the composition, temperature and density profiles for the upper mantle in this region, which can help us understand the nature of thermal and tectonic processes of the Rio Grande Rift.

  7. Sulfide Capacity in Ladle Slag at Steelmaking Temperatures

    Science.gov (United States)

    Allertz, Carl; Sichen, Du

    2015-12-01

    Sulfide capacity measurements were conducted at 1823 K and 1873 K (1550 °C and 1600 °C) for the quaternary Al2O3-CaO-MgO-SiO2 system, for typical compositions used in the ladle in steelmaking. A copper-slag equilibrium was used under controlled oxygen and sulfur potentials. The sulfide capacity is strongly dependent on the composition and it was found to increase with the basic oxides, while it decreases with increase of the acidic components. It was found that CaO is more effective in holding sulfur in the slag compared to MgO when replacing SiO2. For the present slag compositions, Al2O3 and SiO2 behaved similar with respect to sulfur, and no considerable effect could be recorded when replacing one for the other. The sulfide capacity was also found to be strongly dependent on the temperature, increasing with temperature. The present results were compared with industrial data from the ladle, after vacuum treatment, and they were in good agreement.

  8. Recent (2008-10) concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone, south-central Texas, and their potential relation to urban development in the contributing zone

    Science.gov (United States)

    Mahler, Barbara J.; Musgrove, MaryLynn; Herrington, Chris; Sample, Thomas L.

    2011-01-01

    During 2008–10, the U.S. Geological Survey, in cooperation with the City of Austin, the City of Dripping Springs, the Barton Springs/Edwards Aquifer Conservation District, the Lower Colorado River Authority, Hays County, and Travis County, collected and analyzed water samples from five streams (Barton, Williamson, Slaughter, Bear, and Onion Creeks), two groundwater wells (Marbridge well [YD–58–50–704] and Buda well [LR–58–58–403]), and the main orifice of Barton Springs in Austin, Texas, with the objective of characterizing concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone. The Barton Springs zone is in south-central Texas, an area undergoing rapid growth in population and in land area affected by development, with associated increases in wastewater generation. Over a period of 17 months, during which the hydrologic conditions transitioned from dry to wet, samples were collected routinely from the streams, wells, and spring and, in response to storms, from the streams and spring; some or all samples were analyzed for nitrate, nitrogen and oxygen isotopes of nitrate, and waste­water compounds. The median nitrate concentrations in routine samples from all sites were higher in samples collected during the wet period than in samples collected during the dry period, with the greatest difference for stream samples (0.05 milligram per liter during the dry period to 0.96 milligram per liter for the wet period). Nitrate concentrations in recent (2008–10) samples were elevated relative to concentrations in historical (1990–2008) samples from streams and from Barton Springs under medium- and high-flow conditions. Recent nitrate concentrations were higher than historical concentrations at the Marbridge well but the reverse was true at the Buda well. The elevated concentrations likely are related to the cessation of dry conditions coupled with increased nitrogen loading in the

  9. Novel one pot stoichiometric synthesis of nickel sulfide nanomaterials as counter electrodes for QDSSCs

    Energy Technology Data Exchange (ETDEWEB)

    Mani, A. Daya; Deepa, Melepurath [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India); Xanthopoulos, N. [Ecole Polytechnique Federale de Lausanne (EPFL), CH-Lausanne (Switzerland); Subrahmanyam, Ch, E-mail: csubbu@iith.ac.in [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India)

    2014-11-14

    Solution combustion synthesis has been used for the first time to synthesize metal sulfide nanomaterials. Selective stoichiometric synthesis of nickel sulfide nanomaterials was achieved in a single step by using combustion synthesis under ambient conditions and the samples were tested as counter electrodes in a typical quantum dot sensitized solar cell (QDSSC). By varying the oxidant/fuel ratio, different stoichiometric nickel sulfide nanomaterials were obtained. Interestingly, a maximum of fourfold increase in efficiency (1.1%) was achieved with nickel sulfide counter electrode when compared to the Pt counter electrode (0.25%). This can be attributed to the less charge transfer resistance offered by nickel sulfide samples compared to Pt, which was confirmed by electrochemical impedance spectroscopy. Among different stoichiometric compositions of nickel sulfide, Ni{sub 3}S{sub 2} was found to exhibit the least charge transfer resistance and superior solar cell efficiency. The present study describes a novel selective stoichiometric synthetic approach and facile fabrication procedure for low cost counter electrode materials in QDSSCs. - Highlights: • Novel and facile phase selective synthesis of nickel sulfide nanomaterials. • A different sensitization approach of TiO{sub 2} with CdS. • A simple paint approach for working and counter electrode fabrication. • Fourfold increase of efficiency with Ni{sub 3}S{sub 2} compared to the conventional Pt.

  10. Enrichment and immobilization of sulfide removal microbiota applied for environmental biological remediation of aquaculture area.

    Science.gov (United States)

    Zhao, Yang-Guo; Zheng, Yu; Tian, Weijun; Bai, Jie; Feng, Gong; Guo, Liang; Gao, Mengchun

    2016-07-01

    To remove sulfide in the deteriorating aquaculture sediment and water, sulfide-oxidizing microbiota was enriched from Jiaozhou Bay, China, by using sulfide-rich medium. Composition and structure of microbial communities in the enrichments were investigated by 16S rDNA molecular biotechniques. Results showed that microbial community structure continuously shifted and the abundance of sulfate reducing bacteria, i.e., Desulfobacterium, Desulfococcus and Desulfobacca apparently declined. Several halophile genera, Vibrio, Marinobacter, Pseudomonas, Prochlorococcus, Pediococcus and Thiobacillus predominated finally in the microbiota. The enriched microbiota was capable of removing a maximum of 1000 mg/L sulfide within 12 h with 10% inoculum at pH 7.0, 20-30 °C. After immobilized, the microbiota presented excellent resistance to impact and could completely remove 600 mg/L sulfide in 12 h. Moreover, the immobilized microbiota recovered well even recycled for five times. In conclusion, the immobilized sulfide-removing microbiota showed a quite promising application for biological restoring of sulfide-rich aquaculture environment.

  11. Anhydrous ringwoodites in the mantle transition zone: Their bulk modulus, solid solution behavior, compositional variation, and sound velocity feature

    Directory of Open Access Journals (Sweden)

    Xi Liu

    2016-06-01

    Full Text Available The isothermal bulk moduli of anhydrous Mg2SiO4-ringwoodite (Rw and Fe2SiO4-Rw, and other 4–2 oxide spinels at ambient P-T condition have been evaluated, and empirically fitted to a model as KT0 = 270.8(300 + 0.343(59*V0 + 23.04(269*EN-total, where KT0 is the isothermal bulk modulus in GPa, V0 the unit-cell volume in Å3 and EN-total the electronegativity total of all cations in the chemical formula. This model well reproduces all data used in its calibration, and may be used to predict the KT0 of other 4–2 oxide spinels. Combined with the generally linear volume–composition relationship of the Rw solid solutions along the join Mg2SiO4–Fe2SiO4, this model leads to a much smaller composition effect on the KT0: KT0 = 185.0(1 + 7.0(1*XFe, where XFe is the atomic ratio Fe/(Fe + Mg. Furthermore, a bulk composition-independent compositional variation with P has been disclosed for the Rw at the P-T conditions of the lower part of the mantle transition zone (MTZ: XFe = 0.222(41 – 0.0053(19*P, with P in GPa. The nearly ideal mixing behavior, much smaller composition effect on the bulk modulus, and significant compositional variation of the Rw in the lower part of the MTZ substantially increase the gradients of the Vs-P and Vp-P profiles to generally match those constrained by the seismic reference models PREM and AK135. If there is any global low-T anomaly at the depth of 660 km, its required magnitude is most likely not larger than 200 K.

  12. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  13. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  14. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  15. Influence of groundwater depth on species composition and community structure in the transition zone of Cele oasis

    Institute of Scientific and Technical Information of China (English)

    Frank; M.; THOMAS

    2010-01-01

    The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins.

  16. Influence of groundwater depth on species composition and community structure in the transition zone of Cele oasis

    Institute of Scientific and Technical Information of China (English)

    XiangYi LI; LiSha LIN; Qiang ZHAO; XiMing ZHANG; Frank M.THOMAS

    2010-01-01

    The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth.The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities.However,besides groundwater depth,the community composition and species diversity were also influenced by physiognomy of the habitat.Based on the similarity coefficient,the differences between dominant plant communities were significant at different groundwater depths.Compared with other results relating to desert vegetation and groundwater depth,variations of community distribution were similar at the large spatial scale.However,in this extremely arid region,there were significant differences in community type and community succession when compared with other arid regions,especially in relationship to deep groundwater depth.With groundwater depth from deep to shallow,communities transformed with the sequence of Alhagi communities,Tamarix spp.communities,Populus communities,Phragmites communities,and Sophora communities.At groundwater depth of less than 6.0m,the community type and composition changed,and the species diversity increased.Among these dominant species,Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth,which means it possessed the best adaptability to environmental conditions at the oasis margins.

  17. Composition and interactions among bacterial, microeukaryotic and T4-like viral assemblages in lakes from both polar zones

    Directory of Open Access Journals (Sweden)

    Daniel eAguirre De Cárcer

    2016-03-01

    Full Text Available In this study we assess global biogeography and correlation patterns among three components of microbial life: bacteria, microeukaryotes, and T4-like myoviruses. In addition to environmental and biogeographical considerations, we have focused our study on samples from high-latitude pristine lakes from both poles, since these simple island-like ecosystems represent ideal ecological models to probe the relationships among microbial components and with the environment. Bacterial assemblages were dominated by members of the same groups found to dominate freshwater ecosystems elsewhere, and microeukaryotic assemblages were dominated by photosynthetic microalgae. Despite inter-lake variations in community composition, the overall percentages of OTUs shared among sites was remarkable, indicating that many microeukaryotic, bacterial, and viral OTUs are globally-distributed. We observed an intriguing negative correlation between bacterial and microeukaryotic diversity values. Notably, our analyses show significant global correlations between bacterial and microeukaryotic community structures, and between the phylogenetic compositions of bacterial and T4-like virus assemblages. Overall, environmental filtering emerged as the main factor driving community structures.

  18. Detecting Safety Zone Drill Process Parameters for Uncoated HSS Twist Drill in Machining GFRP Composites by Integrating Wear Rate and Wear Transition Mapping

    Directory of Open Access Journals (Sweden)

    Sathish Rao Udupi

    2016-01-01

    Full Text Available The previous research investigations informed that the tool wear of any machining operation could be minimized by controlling the machining factors such as speed, feed, geometry, and type of cutting tool. Hence the present research paper aims at controlling the process parameters to minimize the drill tool wear, during the machining of Glass Fiber Reinforced Polymer (GFRP composites. Experiments were carried out to find the tool wear rate and a wear mechanism map of uncoated High Speed Steel (HSS drill of 10 mm diameter was developed for the drilling of GFRP composite laminates. The surface micrograph images on the drill land surface displayed dominant wear mechanisms induced on HSS drill during machining of GFRP and they were found to be adhesive wear, adhesive and abrasive wear, abrasive wear, and diffusion and fatigue wear. A “safety wear zone” was identified on the wear mechanism map, where the minimum tool wear of the HSS drill occurs. From the safety zone boundaries, it was inferred that the drill spindle speed should be set between 1200 and 1590 rpm and feed rate must be set within a range of 0.10–0.16 mm/rev for GFRP work and HSS tool combination to enhance the service life of 10 mm HSS drills and to minimize the tool wear.

  19. Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand.

    Science.gov (United States)

    Kaur, Gurpreet; Mountain, Bruce W; Stott, Matthew B; Hopmans, Ellen C; Pancost, Richard D

    2015-03-01

    Microbial adaptations to environmental extremes, including high temperature and low pH conditions typical of geothermal settings, are of interest in astrobiology and origin of life investigations. The lipid biomarkers preserved in silica deposits associated with six geothermal areas in the Taupo Volcanic Zone were investigated and variations in lipid composition as a function of temperature and pH were assessed. Lipid analyses reveal highly variable abundances and distributions, reflecting community composition as well as adaptations to extremes of pH and temperature. Biomarker profiles reveal three distinct microbial assemblages across the sites: the first in Champagne Pool and Loop Road, the second in Orakei Korako, Opaheke and Ngatamariki, and the third in Rotokawa. Similar lipid distributions are observed in sinters from physicochemically similar springs. Furthermore, correlation between lipid distributions and geothermal conditions is observed. The ratio of archaeol to bacterial diether abundance, bacterial diether average chain length, degree of GDGT cyclisation and C31 and C32 hopanoic acid indices typically increase with temperature. At lower pH, the ratio of archaeol to bacterial diethers, degree of GDGT cyclisation and C31 and C32 hopanoic acid indices are typically higher. No trends in fatty acid distributions with temperature or pH are evident, likely reflecting overprinting due to population influences.

  20. S/Se In Sulfide Inclusion In Diamond

    Science.gov (United States)

    Thomassot, E.; Couffignal, F.; Lorand, J.; Bureau, H.; Cartigny, P.; Harris, J. W.

    2009-05-01

    Sulfides are among the most common minerals found as inclusions in diamonds. Being protected from any alteration after diamond formation, they likely represent the most pristine sulfide sample of mantle rocks. Their chemical composition in major and minor elements (mainly Ni, Cu and Cr), as determined using Electron Probe Micro Analyse (EPMA), is commonly used to determine the rock type in which the diamond formed. Here we propose to apply the same technique to the trace element abundance determination. We performed selenium (Se) on sulfide inclusion in diamonds. The S/Se value could help understanding whether the diamond formed in an eclogitic or peridotitic environment and may also constrain on the magmatic differentiation of diamonds host rock as well as provide a potential surface (hydrothermal) signature in diamond inclusions. A trace element measurement scheme has been developed by EPMA at the CAMPARIS centre (Paris). Se-abundance was obtained using a 30 kV accelerating voltage and 100nA probe current. Total counting time was 800s for peak (1.1 Å ) and 400s for background on both side of peak. Analyses were duplicated by μPIXE using the LPS nuclear microprobe facility (SIS2M CEA Saclay, France). Maps from 30x30 μm2 to 70x70 μm2 were obtained by scanning a 4x4 μm2 proton beam of 3MeV, 600 pA, (0.4 to 2 μC). The two techniques show good agreement and we conclude that EPMA is well suited for accurate and precise Se measurements. We analysed five samples; two monosulfide solid solution (MSS) (Ni>22wt%) typical of the peridotitic paragenesis (P-type), and three Ni-poor sulfides (Ni<7wt%) typical of the eclogitic paragenesis (E-type). In P-type sulfides, Se-content (260 ppm) is significantly higher than previously reported in sulfides from mantle-derived lherzolites (40-160 ppm), pyroxenites (25-45 ppm) or harzburgite. The value of S/Se in MSS is low (˜1400) compared to those of the primitive mantle reservoir (3,300; McDounough et al., 1995 Chemical Geology

  1. Formation of mercury sulfide from Hg(II)−thiolate complexes in natural organic matter

    Science.gov (United States)

    Alain Manceau,; Cyprien Lemouchi,; Mironel Enescu,; Anne-Claire Gaillot,; Martine Lanson,; Valerie Magnin,; Pieter Glatzel,; Poulin, Brett; Ryan, Joseph N.; Aiken, George R.; Isabelle Gautier-Lunea,; Kathryn L. Nagy,

    2015-01-01

    Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, TN, in the United States. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified a chemical reaction mechanism that is thermodynamically favorable in which thiol-bound mercury polymerizes to mercury–sulfur clusters. The clusters form by elimination of sulfur from the thiol complexes via breaking of mercury–sulfur bonds as in an alkylation reaction. Addition of sulfide is not required. This nucleation mechanism provides one explanation for how mercury may be immobilized, and eventually sequestered, in oxygenated surface environments.

  2. Hydrogen sulfide waste treatment by microwave plasma-chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, J.B.L.; Doctor, R.D.

    1994-03-01

    A waste-treatment process that recovers both hydrogen and sulfur from industrial acid-gas waste streams is being developed to replace the Claus technology, which recovers only sulfur. The proposed process is derived from research reported in the Soviet technical literature and uses microwave (or radio-frequency) energy to initiate plasma-chemical reactions that dissociate hydrogen sulfide into elemental hydrogen and sulfur. This process has several advantages over the current Claus-plus-tail-gas-cleanup technology, which burns the hydrogen to water. The primary advantage of the proposal process is its potential for recovering and recycling hydrogen more cheaply than the direct production of hydrogen. Since unconverted hydrogen sulfide is recycled to the plasma reactor, the plasma-chemical process has the potential for sulfur recoveries in excess of 99% without the additional complexity of the tail-gas-cleanup processes associated with the Claus technology. There may also be some environmental advantages to the plasma-chemical process, because the process purge stream would primarily be the carbon dioxide and water contained in the acid-gas waste stream. Laboratory experiments with pure hydrogen sulfide have demonstrated the ability of the process to operate at or above atmospheric pressure with an acceptable hydrogen sulfide dissociation energy. Experiments with a wide range of acid-gas compositions have demonstrated that carbon dioxide and water are compatible with the plasma-chemical dissociation process and that they do not appear to create new waste-treatment problems. However, carbon dioxide does have negative impacts on the overall process. First, it decreases the hydrogen production, and second, it increases the hydrogen sulfide dissociation energy.

  3. Biogeographic Congruency among Bacterial Communities from Terrestrial Sulfidic Springs

    Directory of Open Access Journals (Sweden)

    Brendan eHeadd

    2014-09-01

    Full Text Available Terrestrial sulfidic springs support diverse microbial communities by serving as stable conduits for geochemically diverse and nutrient-rich subsurface waters. Microorganisms that colonize terrestrial springs likely originate from groundwater, but may also be sourced from the surface. As such, the biogeographic distribution of microbial communities inhabiting sulfidic springs should be controlled by a combination of spring geochemistry and surface and subsurface transport mechanisms, and not necessarily geographic proximity to other springs. We examined the bacterial diversity of seven springs to test the hypothesis that occurrence of taxonomically similar microbes, important to the sulfur cycle, at each spring is controlled by geochemistry. Complementary Sanger sequencing and 454 pyrosequencing of 16S rRNA genes retrieved five proteobacterial classes, and Bacteroidetes, Chlorobi, Chloroflexi, and Firmicutes phyla from all springs, which suggested the potential for a core sulfidic spring microbiome. Among the putative sulfide-oxidizing groups (Epsilonproteobacteria and Gammaproteobacteria, up to 83% of the sequences from geochemically similar springs clustered together. Abundant populations of Hydrogenimonas-like or Sulfurovum-like spp. (Epsilonproteobacteria occurred with abundant Thiothrix and Thiofaba spp. (Gammaproteobacteria, but Arcobacter-like and Sulfurimonas spp. (Epsilonproteobacteria occurred with less abundant gammaproteobacterial populations. These distribution patterns confirmed that geochemistry rather than biogeography regulates bacterial dominance at each spring. Potential biogeographic controls were related to paleogeologic sedimentation patterns that could control long-term microbial transport mechanisms that link surface and subsurface environments. Knowing the composition of a core sulfidic spring microbial community could provide a way to monitor diversity changes if a system is threatened by anthropogenic processes or

  4. Zinc sulfide in intestinal cell granules of Ancylostoma caninum adults

    Energy Technology Data Exchange (ETDEWEB)

    Gianotti, A.J.; Clark, D.T.; Dash, J. (Portland State Univ., OR (USA))

    1991-04-01

    A source of confusion has existed since the turn of the century about the reddish brown, weakly birefringent 'sphaerocrystals' located in the intestines of strongyle nematodes, Strongylus and Ancylostoma. X-ray diffraction and energy dispersive spectrometric analyses were used for accurate determination of the crystalline order and elemental composition of the granules in the canine hookworm Ancylostoma caninum. The composition of the intestinal pigmented granules was identified unequivocally as zinc sulfide. It seems most probable that the granules serve to detoxify high levels of metallic ions (specifically zinc) present due to the large intake of host blood.

  5. Composition and abundance of zooplankton in the limnetic zone of seven reservoirs of the Paranapanema River, Brazil

    Directory of Open Access Journals (Sweden)

    E. V. SAMPAIO

    Full Text Available The species composition and abundance of the zooplankton community of seven reservoirs of the Paranapanema River, located between 22º37'-23º11'S and 48º55'-50º32'W, were analysed over four periods, in the year of 1979. The zooplankton community was composed of 76 species of Rotifera, 26 species of Cladocera and 7 species of Copepoda. For a large part of the period under study the Rotifera were dominant, followed by Copepoda. The Piraju and Salto Grande reservoirs, which occupy intermediate positions in the cascade of reservoirs, were richest in species, most of them belonging to Rotifera and Cladocera. In the reservoirs Rio Pari and Rio Novo, lateral to the cascade of reservoirs, a lower species richness was observed, although higher densities of organisms were found than in the other reservoirs located in the main river body. Different rotifer species occurred in succession, being abundant in different periods, with no defined pattern. Among the copepods, Thermocyclops decipiens predominated in the majority of the reservoirs. Ceriodaphnia cornuta was the most abundant cladoceran in the intermediate reservoirs of the cascade, and Daphnia gessneri, Bosminopsis deitersi and Moina minuta, in the reservoirs lateral to the cascade. The most frequent zooplankton species were Notodiaptomus conifer, Thermocyclops decipiens, Ceriodaphnia cornuta cornuta and C. cornuta rigaudi, Daphnia gessneri, Bosmina hagmanni, Keratella cochlearis and Polyarthra vulgaris. Some relationships were found between the trophic state of the reservoirs and the zooplankton community.

  6. Redox Biochemistry of Hydrogen Sulfide*

    OpenAIRE

    Kabil, Omer; Banerjee, Ruma

    2010-01-01

    H2S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of γ-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H2S production in the vasculature. However, patients with inherited deficiency in γ-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxid...

  7. Hydrogen sulfide and translational medicine

    OpenAIRE

    Guo, Wei; Cheng, Ze-yu; Zhu, Yi-Zhun

    2013-01-01

    Hydrogen sulfide (H2S) along with carbon monoxide and nitric oxide is an important signaling molecule that has undergone large numbers of fundamental investigations. H2S is involved in various physiological activities associated with the regulation of homeostasis, vascular contractility, pro- and anti-inflammatory activities, as well as pro- and anti-apoptotic activities etc. However, the actions of H2S are influenced by its concentration, reaction time, and cell/disease types. Therefore, H2S...

  8. Origin of the deep fluids in the paleosubduction zones in western Tianshan: Evidence from Pb- and Sr-isotope compositions of high-pressure veins and host rocks

    Institute of Scientific and Technical Information of China (English)

    HUANG; Dezhi; GAO; Jun; DAI; Tageng; ZOU; Haiyang; XIONG; X

    2005-01-01

    Fluids in the deep subduction zones play an important role in crust-mantle exchange related to the subduction process. Identification of fluids origin, internal or external, can help us to evaluate the contribution of crust materials to mantle during this process. High-pressure veins, which developed in the western Tianshan HP-metamorphic belt extensively, are the direct products of the fluids in subduction zones. In western Tianshan, high-pressure veins and host rocks have overall Pb- and Sr-isotope compositions. At t = 340 Ma, the high-pressure metamorphic time, the ratios of 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb and 87Sr/86Sr of high pressure veins are 17.122―18.431, 15.477―15.611, 37.432―38.689 and 0.70529―0.70705, and are 17.605―17.834, 15.508―15.564, 37.080―38.145 and 0.70522―0.70685 for host rocks. However, high-pressure veins show a much larger variation in Pb-isotope compositions than host rocks. Plots of samples are distributed roughly along a line parallel to and far away from the Northern Hemisphere reference line (NHRL) on the plot of 206Pb/204Pb vs 207Pb/204Pb. On the plot of 206Pb/204Pb vs 208Pb/204Pb, plots of data are distributed nearby mid-ocean-ridge basalts (MORB) area or along a line parallel to and not far away from NHRL, which shows that the data plots are farther away from MORB and ocean island basalts (OIB) areas on the plot of 206Pb/204Pb vs 207Pb/204Pb than on the plot of 206Pb/204Pb vs 208Pb/204Pb. The compositions of Pb- and Sr-isotopes of these high-pressure metamorphic rocks are between that of enriched mantle 1(EMI) and of sediments or upper crust. A notable characteristic can be seen from plots of Pb-isotope ratio vs Pb-isotope ratio and 206Pb/204Pb vs 87Sr/86Sr that array of plots shows an evident tendency of mixture of two end members. Ratios of Rb/Ba, Ce/Pb, Nb/U and Ta/U of high-pressure veins and host rocks are between that of OIB or MORB and that of continental crust, which indicates that continental crust

  9. Trace elements in sulfide inclusions from Yakutian diamonds

    Science.gov (United States)

    Bulanova, G. P.; Griffin, W. L.; Ryan, C. G.; Shestakova, O. Y.; Barnes, S.-J.

    1996-07-01

    Sulfide inclusions in diamonds may provide the only pristine samples of mantle sulfides, and they carry important information on the distribution and abundances of chalcophile elements in the deep lithosphere. Trace-element abundances were measured by proton microprobe in >50 sulfide inclusions (SDI) from Yakutian diamonds; about half of these were measured in situ in polished plates of diamonds, providing information on the spatial distribution of compositional variations. Many of the diamonds were identified as peridotitic or eclogitic from the nature of coexisting silicate or oxide inclusions. Known peridotitic diamonds contain SDIs with Ni contents of 22 36%, consistent with equilibration between olivine, monosulfide solid solution (MSS) and sulfide melt, whereas SDIs in eclogitic diamonds contain 0 12% Ni. A group of diamonds without silicate or oxide inclusions has SDIs with 11 18% Ni, and may be derived from pyroxenitic parageneses. Eclogitic SDIs have lower Ni, Cu and Te than peridotitic SDIs; the ranges of the two parageneses overlap for Se, As and Mo. The Mo and Se contents range up to 700 and 300 ppm, respectively; the highest levels are found in peridotitic diamonds. Among the in-situ SDIs, significant Zn and Pb levels are found in those connected by cracks to diamond surfaces, and these elements reflect interaction with kimberlitic melt. Significant levels of Ru (30 1300 ppm) and Rh (10 170 ppm) are found in many peridotitic SDIs; SDIs in one diamond with wustite and olivine inclusions and complex internal structures have high levels of other platinum-group elements (PGEs) as well, and high chondrite-normalized Ir/Pd. Comparison with experimental data on element partitioning between crystals of monosulfide solid solution (MSS) and sulfide melts suggests that most of the inclusions in both parageneses were trapped as MSS, while some high-Cu SDIs with high Pd±Rh may represent fractionated sulfide melts. Spatial variations of SDI composition within

  10. Growth and chemosensory behavior of sulfate-reducing bacteria in oxygen-sulfide gradients

    DEFF Research Database (Denmark)

    Sass, Andrea M.; Wieland, Andrea Eschemann; Kühl, Michael;

    2002-01-01

    Growth and chemotactic behavior in oxic–anoxic gradients were studied with two freshwater and four marine strains of sulfate-reducing bacteria related to the genera Desulfovibrio, Desulfomicrobium or Desulfobulbus. Cells were grown in oxygen–sulfide counter-gradients within tubes filled with agar...... chemotactically to lactate, nitrate, sulfate and thiosulfate, and even sulfide functioned as an attractant. In oxic–anoxic gradients the bacteria moved away from high oxygen concentrations and formed bands at the outer edge of the oxic zone at low oxygen concentration (

  11. Nanoparticles of noble metals in the supergene zone

    Science.gov (United States)

    Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

    2012-04-01

    Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon

  12. Controls on Highly Siderophile Element Concentrations in Martian Basalt: Sulfide Saturation and Under-Saturation

    Science.gov (United States)

    Righter, Kevin

    2009-01-01

    Highly siderophile elements (HSE; Re, Au and the platinum group elements) in shergottites exhibit a wide range from very high, similar to the terrestrial mantle, to very low, similar to sulfide saturated mid ocean ridge basalt (e.g., [1]). This large range has been difficult to explain without good constraints on sulfide saturation or under-saturation [2]. A new model for prediction of sulfide saturation places new constraints on this problem [3]. Shergottite data: For primitive shergottites, pressure and temperature estimates are between 1.2-1.5 GPa, and 1350-1470 C [4]. The range of oxygen fugacities is from FMQ-2 to IW, where the amount of Fe2O3 is low and thus does not have a significant effect on the S saturation values. Finally, the bulk compositions of shergottites have been reported in many recent studies (e.g., [5]). All of this information will be used to test whether shergottites are sulfide saturated [3]. Modeling values and results: The database for HSE partition coefficients has been growing with many new data for silicates and oxides [6-8] to complement a large sulfide database [9- 11]. Combining these data with simple batch melting models allows HSE contents of mantle melts to be estimated for sulfide-bearing vs. sulfide-free mantle. Combining such models with fractional crystallization modeling (e.g., [12]) allows HSE contents of more evolved liquids to be modeled. Most primitive shergottites have high HSE contents (and low S contents) that can be explained by sulfide under-saturated melting of the mantle. An exception is Dhofar 019 which has high S contents and very low HSE contents suggesting sulfide saturation. Most evolved basaltic shergottites have lower S contents than saturation, and intermediate HSE contents that can be explained by olivine, pyroxene, and chromite fractionation. An exception is EET A79001 lithology B, which has very low HSE contents and S contents higher than sulfide saturation values . evidence for sulfide saturation

  13. Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms.

    Directory of Open Access Journals (Sweden)

    Desirée Villahermosa

    Full Text Available Nitrate decreases sulfide release in wastewater treatment plants (WWTP, but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm showed low sulfide production (0.31 μmol cm-3 h-1 and oxygen consumption rates (0.01 μmol cm-3 h-1. The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1. Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB. This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1 an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2 a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR

  14. Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms

    Science.gov (United States)

    Villahermosa, Desirée; Corzo, Alfonso; Garcia-Robledo, Emilio; González, Juan M.; Papaspyrou, Sokratis

    2016-01-01

    Nitrate decreases sulfide release in wastewater treatment plants (WWTP), but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm) showed low sulfide production (0.31 μmol cm-3 h-1) and oxygen consumption rates (0.01 μmol cm-3 h-1). The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1). Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR) in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB). This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB) were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1) an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2) a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR-SOB syntrophic

  15. Sulfide intrusion and detoxification in seagrasses ecosystems

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis, tracing sulfur compounds combined with ecosystem parameters we found different spatial, intraspecific and interspecific strategies to cope with sulfidic sediments. 1......) Tolerance, by elimination (eg. Zostera marina); where we found precipitation of sulfide as non-toxic elemental sulfur on the inner wall of the root lacunae. 2) Utilization (eg. Z. marina), where seagrasses detoxify and incorporate sulfides by active uptake and metabolize to sulfate, representing a non...

  16. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  17. Multiple magmatism in an evolving suprasubduction zone mantle wedge: The case of the composite mafic-ultramafic complex of Gaositai, North China Craton

    Science.gov (United States)

    Yang, Fan; Santosh, M.; Tsunogae, T.; Tang, Li; Teng, Xueming

    2017-07-01

    The suprasubduction zone mantle wedge of active convergent margins is impregnated by melts and fluids leading to the formation of a variety of magmatic and metasomatic rock suites. Here we investigate a composite mafic-ultramafic intrusion at Gaositai, in the northern margin of the North China Craton (NCC). The hornblende gabbro-serpentinite-dunite-pyroxenite-gabbro-diorite suite surrounded by hornblendites of this complex has long been considered to represent an ;Alaskan-type; zoned pluton. We present petrologic, mineral chemical, geochemical and zircon U-Pb and Lu-Hf data from the various rock types from Gaositai including hornblende gabbro, serpentinite, dunite, pyroxenite, diorite and the basement hornblendite which reveal the case of multiple melt generation and melt-peridotite interaction. Our new mineral chemical data from the mafic-ultramafic suite exclude an ;Alaskan-type; affinity, and the bulk geochemical features are consistent with subduction-related magmatism with enrichment of LILE (K, Rb, and Ba) and LREE (La and Ce), and depletion of HFSE (Nb, Ta, Zr, and Hf) and HREE. Zircon U-Pb geochronology reveals that the hornblendites surrounding the Gaositai complex are nearly 2 billion years older than the intrusive complex and yield early Paleoproterozoic emplacement ages (2433-2460 Ma), followed by late Paleoproterozoic metamorphism (1897 Ma). The serpentinites trace the history of a long-lived and replenished ancient sub-continental lithospheric mantle with the oldest zircon population dated as 2479 Ma and 1896 Ma, closely corresponding with the ages obtained from the basement rock, followed by Neoproterozoic and Phanerozoic zircon growth. The oldest member in the Gaositai composite intrusion is the dunite that yields emplacement age of 755 Ma, followed by pyroxenite formed through the interaction of slab melt and wedge mantle peridotite at 401 Ma. All the rock suites also carry multiple population of younger zircons ranging in age from Paleozoic to

  18. Abundance and species composition of planktonic Ciliophora from the wastewater discharge zone in the Bahía Blanca Estuary, Argentina

    Directory of Open Access Journals (Sweden)

    María Sonia Barría de Cao

    2003-09-01

    Full Text Available The specific composition and abundance variation of the ciliate community from a wastewater discharge zone in the Bahía Blanca estuary, Argentina, were studied all throughout a year, from June 1995 to May 1996. The polluted area exhibited high values of particulate organic matter and nutrients, particularly phosphates. Aloricate ciliates were represented by 15 species belonging to the genera Strombidium Claparède & Lachmann, 1859; Strombidinopsis Kent, 1881; Cyrtostrombidium Lynn & Gilron, 1993; Strobilidium Schewiakoff, 1983; Lohmmanniella Leegaard, 1915 and Tontonia Fauré-Fremiet, 1914. Tintinnids were represented by nine species belonging to the genera Tintinnidium Kent, 1881, Tintinnopsis Stein, 1867 and Codonellopsis Jörgensen, 1924. The total abundance of aloricate ciliates reached a peak of 1,800 ind. 1-1 and the total abundance of tintinnids reached a peak of 9,400 ind. 1-1. Tintinnidium balechi Barría de Cao, 1981 was the most abundant ciliate in the community. Considerations on the presence and abundance of ciliates are made in relation to physicochemical and biochemical parameters.

  19. Short-term variability and long-term change in the composition of the littoral zone fish community in Spirit Lake, Iowa

    Science.gov (United States)

    Pierce, C.L.; Sexton, M.D.; Pelham, M.E.; Larscheid, J.G.

    2001-01-01

    We assessed short-term variability and long-term change in the composition of the littoral fish community in Spirit Lake, Iowa. Fish were sampled in several locations at night with large beach seines during spring, summer and fall of 1995-1998. Long-term changes were inferred from comparison with a similar study conducted over 70 y earlier in Spirit Lake. We found 26 species in the littoral zone. The number of species per sample ranged from 4 to 18, averaging 11.8. The average number of species per sample was higher at stations with greater vegetation density. A distinct seasonal pattern was evident in the number of species collected per sample in most years, increasing steadily from spring to fall. Patterns of variability within our 1995-1998 study period suggest that: (1) numerous samples are necessary to adequately characterize a littoral fish community, (2) sampling should be done when vegetation and young-of-year densities are highest and (3) sampling during a single year is inadequate to reveal the full community. The number of native species has declined by approximately 25% over the last 70 y. A coincident decline in littoral vegetation and associated habitat changes during the same period are likely causes of the long-term community change.

  20. Optimisation for the separation of the oligosaccharide, sodium Pentosan Polysulfate by reverse polarity capillary zone electrophoresis using a central composite design.

    Science.gov (United States)

    Prochazka, S; Mulholland, M; Lloyd-Jones, A

    2003-02-01

    The separation by reverse polarity capillary zone electrophoresis of the therapeutically developed sodium salt of Pentosan Polysulfate was optimised through the analysis of response surface methodologies, modeled using a central composite design. The optimisation investigated injection pressure, injection time and voltage and the effect of the conditions on retention times, peak areas, separation efficiency and the method sensitivity. The overall goal was to develop the most sensitive results with no decrease in separation efficiency. The following results were obtained: (1) retention times generally decreased as injection pressure, injection time and voltage increased, injection time having the least effect; (2) as expected peak areas increased as injection pressure and injection time increased but decreased as voltage increased; (3) separation efficiencies generally increased as injection pressure and injection time decreased, with voltage having almost no effect. For the optimum condition, the sample was introduced at the inlet vial at the cathode hydrodynamically, at optimal setting of 44 s at 35 mbar. The optimal voltage was -20 kV. In comparison with other methods, the optimum showed increased sensitivity, resolution and separation efficiency. Repeatability studies were performed on the optimum parameter conditions. Relative standard deviation values obtained were between 0.9 and 5.4%.

  1. Treatment of teeth in the esthetic zone in a patient with amelogenesis imperfecta using composite veneers and the clear matrix technique: A case report

    Directory of Open Access Journals (Sweden)

    Bogosavljević Aleksandar

    2016-01-01

    Full Text Available Introduction. Restorative dental treatment of patients with a generalized form of amelogenesis imperfecta (AI remains a challenge even today. The treatment approach is multidisciplinary and includes action of several dental disciplines such as restorative, orthodontic, and prosthetic dental specialties. Case report. A 18-year-old female patent was referred to the Department of Restorative Dentistry and Periodontology at the Military Medical Academy of Belgrade, Serbia. She was diagnosed with AI and formerly had been treated for a long period of time at the Department of Pediatric Dentistry and Orthodontics. Her primary concern upon arrival was discomfort and concern for the esthetic appearance of the anterior teeth. The treatment was done with the modified clear matrix technique used in composite veneer restoration of teeth in the esthetic zone. Conclusion. Because fixed prosthetic restoration with crowns, is the final treatment of AI patients it involves severe tooth structure loss. The clear matrix method which was done in this case allowed for greater comfort, functionality, simplicity, speed, greater economic efficiency and tooth structure preservation.

  2. The geology and petrology of Volcán San Juan (Nayarit, México) and the compositionally zoned Tepic Pumice

    Science.gov (United States)

    Luhr, James F.

    2000-01-01

    Volcán San Juan is the westernmost Quaternary composite volcano in the Mexican Volcanic Belt. Its activity is divided into three stages of decreasing eruptive volume. During stage-1 activity, the main cone of San Juan and the adjacent Cerro Alto grew to a combined volume of ˜60 km 3 through eruption of hornblende-bearing andesites, dacites, and rhyodacites. Stage 1 included explosive eruptions of hornblende-dacite and an andesite dated at 33,750 a (years ago) and 23,010 a. Stage-2 activity involved a major Plinian eruption 14,770 a that produced the hypersthene-hornblende-bearing, compositionally zoned, rhyodacitic-andesitic Tepic Pumice and led to formation of an oval-shaped caldera 4×1 km in diameter. Tepic, the capital city of Nayarit State, with a population of ˜250,000, lies at the NE foot of Volcán San Juan. This location was buried under 2-9 m of rhyodacitic pumice-fall deposits from the Tepic Pumice eruption. Erosion has since removed virtually all exposures of Tepic Pumice >15 km from the caldera. The estimated volume of erupted tephra is 5.6 km 3, equivalent to 1.2 km 3 of magma. Modeling of the eruption dynamics indicates that as the eruption evolved the column height increased from ˜15 km to ˜24 km and maximum mass discharge rate increased from ˜3×10 6 kg/s to ˜6×10 7 kg/s. During stage-3 activity, a hornblende-andesitic lava dome partially filled the caldera and sent block lava flows down the north slope of the cone; total erupted volume was ˜0.55 km 3. Compared to other composite volcanoes of the western Mexican Volcanic Belt, the products from San Juan have the highest Sr contents and the lowest Rb, Y, Yb, and Lu contents, resulting in high La/Yb and Sr/Y, with low Rb/Sr. These observations indicate a strong slab-melt component at San Juan, consistent with its proximity to the Middle America Trench where young, hot lithosphere is subducting. The San Juan andesites, dacites, and rhyodacites also have relatively high 87Sr/ 86Sr, 206Pb/ 204

  3. Detecting Naturally-Produced Sulfide Nanoparticles by Adsorptive, Cathodic Stripping Voltammetry.

    Science.gov (United States)

    Helz, G. R.; Krznaric, D.; Bura-Nakic, E.; Ciglenecki, I.

    2007-12-01

    Growing evidence implies that metal sulfide nanoparticles of natural origin exist in some aquatic environments. These nanoparticles could play important roles as mediators of trace metal nutrition and toxicity. Thermodynamics suggests that in sulfidic environments (total transition metaltotal sulfide) the most insoluble metal sulfide (usually Hg or Cu) will form the predominant sulfide nanoparticle. New experimental methods for detecting and distinguishing between such nanoparticles are needed. We report that mercury electrodes effectively preconcentrate a number of different metal sulfide nanoparticles, enabling their detection by adsorptive cathodic stripping voltammetry. Voltammetrically, nanoparticulate analytes differ fundamentally from dissolved analytes; e.g. analyte accumulation is very sensitive to electrolyte composition and concentration in accord with the Schulze-Hardy Rule. EDTA or acid treatment of samples is useful for distinguishing highly insoluble nanoparticles (HgS, CuS) from FeS. Nanoparticulate sulfur potentially interferes. Supersaturated solutions can generate artifactual analyte on Hg electrode surfaces. Despite such potential pitfalls, progress is encouraging. Preliminary, qualitative results from natural waters will be reported.

  4. Genesis of hydrogen sulfide of the Dauletabad-Donmezskiy gas field

    Energy Technology Data Exchange (ETDEWEB)

    Semenovich, V.V.; Guriyeva, S.M.; Maksimov, S.P.; Mekhtiyeva, V.L.; Pankina, R.G.

    1983-01-01

    An analysis was made of the content of hydrogen sulfide in isotope composition of sulfur in samples of condensation water (from a separator) at the gas-condensate field of DauletabadDonmez. Hydrogen sulfide was very enriched with heavy isotope deltaS/sup 34/ (deltaS/sup 34/ from +9.3 to +15.8 0/00) and close to sulfur of the evaporites of the Jurassic age. The findings are compared to the data of studying isotope composition of sulfur in gas fields of the Maudarya syneclise. A hypothesis is advanced for the origin of hydrogen sulfide in the Dauletabad-Donmezskiy field because of migration from the underlying Jurassic deposits.

  5. Hydrogen sulfide and vascular relaxation

    Institute of Scientific and Technical Information of China (English)

    SUN Yan; TANG Chao-shu; DU Jun-bao; JIN Hong-fang

    2011-01-01

    Objective To review the vasorelaxant effects of hydrogen sulfide (H2S) in arterial rings in the cardiovascular system under both physiological and pathophysiological conditions and the possible mechanisms involved.Data sources The data in this review were obtained from Medline and Pubmed sources from 1997 to 2011 using the search terms "hydrogen sulfide" and ""vascular relaxation".Study selection Articles describing the role of hydrogen sulfide in the regulation of vascular activity and its vasorelaxant effects were selected.Results H2S plays an important role in the regulation of cardiovascular tone.The vasomodulatory effects of H2S depend on factors including concentration,species and tissue type.The H2S donor,sodium hydrosulfide (NarS),causes vasorelaxation of rat isolated aortic rings in a dose-dependent manner.This effect was more pronounced than that observed in pulmonary arterial rings.The expression of KATP channel proteins and mRNA in the aortic rings was increased compared with pulmonary artery rings.H2S is involved in the pathogenesis of a variety of cardiovascular diseases.Downregulation of the endogenous H2S pathway is an important factor in the pathogenesis of cardiovascular diseases.The vasorelaxant effects of H2S have been shown to be mediated by activation of KATP channels in vascular smooth muscle cells and via the induction of acidification due to activation of the CI/HCO3 exchanger.It is speculated that the mechanisms underlying the vasoconstrictive function of H2S in the aortic rings involves decreased NO production and inhibition of cAMP accumulation.Conclusion H2S is an important endogenous gasotransmitter in the cardiovascular system and acts as a modulator of vascular tone in the homeostatic regulation of blood pressure.

  6. Molybdenum sulfide/carbide catalysts

    Science.gov (United States)

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  7. Medical Functions of Hydrogen Sulfide.

    Science.gov (United States)

    Olas, Beata

    2016-01-01

    Hydrogen sulfide (H(2)S) is a gasomediator synthesized from L- and D-cysteine in various tissues. It is involved in a number of physiological and pathological processes. H(2)S exhibits antiatherosclerotic, vasodilator, and proangiogenic properties, and protects the kidney and heart from damage following ischemia/reperfusion injury. H(2)S donors may be natural or synthetic, and may be used for the safe treatment of a wide range of diseases. This review article summarizes the current state of knowledge of the therapeutic function of H(2)S.

  8. Subduction of fracture zones

    Science.gov (United States)

    Constantin Manea, Vlad; Gerya, Taras; Manea, Marina; Zhu, Guizhi; Leeman, William

    2013-04-01

    Since Wilson proposed in 1965 the existence of a new class of faults on the ocean floor, namely transform faults, the geodynamic effects and importance of fracture zone subduction is still little studied. It is known that oceanic plates are characterized by numerous fracture zones, and some of them have the potential to transport into subduction zones large volumes of water-rich serpentinite, providing a fertile water source for magma generated in subduction-related arc volcanoes. In most previous geodynamic studies, subducting plates are considered to be homogeneous, and there is no clear indication how the subduction of a fracture zone influences the melting pattern in the mantle wedge and the slab-derived fluids distribution in the subarc mantle. Here we show that subduction of serpentinized fracture zones plays a significant role in distribution of melt and fluids in the mantle wedge above the slab. Using high-resolution tree-dimensional coupled petrological-termomechanical simulations of subduction, we show that fluids, including melts and water, vary dramatically in the region where a serpentinized fracture zone enters into subduction. Our models show that substantial hydration and partial melting tend to concentrate where fracture zones are being subducted, creating favorable conditions for partially molten hydrous plumes to develop. These results are consistent with the along-arc variability in magma source compositions and processes in several regions, as the Aleutian Arc, the Cascades, the Southern Mexican Volcanic Arc, and the Andean Southern Volcanic Zone.

  9. Ammonia and hydrogen sulfide removal using biochar

    Science.gov (United States)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  10. Micro and nano sulfide solid lubrication

    CERN Document Server

    Wang, Haidou; Liu, Jiajun

    2014-01-01

    Sulfide solid lubrication is a vital field of tribology with the potential to save both energy and materials. This book examines the low-temperature sulfuration technology developed in China, as well as two-step methods for preparing sulfide lubrication films.

  11. Structural studies of copper sulfide films: effect of ambient atmosphere

    Directory of Open Access Journals (Sweden)

    Manisha Kundu et al

    2008-01-01

    Full Text Available We examined the structural properties of copper sulfide films as a function of the sulfurization time of 70-nm-thick Cu films. Copper sulfide films with various phases such as mixed metallic Cu-chalcocite, chalcocite, roxbyite, and covellite phases were formed with increasing sulfurization time. To evaluate the structural stability of various films, all the films were exposed to the ambient atmosphere for the same amount of time. Although the phase structure and stoichiometry of the films were maintained at a greater depth, the near-surface region of the films was oxidized and covered with overlayers of oxide, hydroxide, and/or sulfate species due to the exposure and reaction with the ambient atmosphere. The oxygen uptake and its reactivity with the copper sulfide film surfaces were enhanced with increasing sulfur content of the films. In addition, the type of divalent state of copper formed on the film surfaces depended on the phase structure, composition, and stoichiometry of the films.

  12. Sulfide ceramics in molten-salt electrolyte batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kaun, T.D.; Hash, M.C.; Simon, D.R.

    1995-06-01

    Sulfide ceramics are finding application in the manufacture of advanced batteries with molten salt electrolyte. Use of these ceramics as a peripheral seal component has permitted development of bipolar Li/FeS{sub 2} batteries. This bipolar battery has a molten lithium halide electrolyte and operates at 400 to 450C. Initial development and physical properties evaluations indicate the ability to form metal/ceramic bonded seal (13-cm ID) components for use in high-temperature corrosive environments. These sealants are generally CaAl{sub 2}S{sub 4}-based ceramics. Structural ceramics (composites with oxide or nitride fillers), highly wetting sealant formulations, and protective coatings are also being developed. Sulfide ceramics show great promise because of their relatively low melting point, high-temperature viscous flow, chemical stability, high-strength bonding, and tailored coefficients of thermal expansion. Our methodology of generating laminated metal/ceramic pellets (e.g., molybdenum/sulfide ceramic/molybdenum) with which to optimize materials formulation and seal processing is described.

  13. Sulfide toxicity kinetics of a uasb reactor

    Directory of Open Access Journals (Sweden)

    D. R. Paula Jr.

    2009-12-01

    Full Text Available The effect of sulfide toxicity on kinetic parameters of anaerobic organic matter removal in a UASB (up-flow anaerobic sludge blanket reactor is presented. Two lab-scale UASB reactors (10.5 L were operated continuously during 12 months. The reactors were fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. One of the reactors also received increasing concentrations of sodium sulfide. For both reactors, the flow rate of 16 L.d-1 was held constant throughout the experiment, corresponding to a hydraulic retention time of 15.6 hours. The classic model for non-competitive sulfide inhibition was applied to the experimental data for determining the overall kinetic parameter of specific substrate utilization (q and the sulfide inhibition coefficient (Ki. The application of the kinetic parameters determined allows prediction of methanogenesis inhibition and thus the adoption of operating parameters to minimize sulfide toxicity in UASB reactors.

  14. Hydrothermal sulfide accumulation along the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Jamieson, J. W.; Clague, D. A.; Hannington, M. D.

    2014-06-01

    on the sizes and distribution of hydrothermally-active deposits, may be similarly underestimating the amount of sulfide along the global submarine neovolcanic zones.

  15. Crustal contamination and sulfide immiscibility history of the Permian Huangshannan magmatic Ni-Cu sulfide deposit, East Tianshan, NW China

    Science.gov (United States)

    Mao, Ya-Jing; Qin, Ke-Zhang; Tang, Dong-Mei; Feng, Hong-Ye; Xue, Sheng-Chao

    2016-11-01

    The Huangshannan mafic-ultramafic intrusion is a Permian Ni-Cu sulfide-bearing intrusion in the southern margin of the Central Asian Orogenic Belt. The intrusion consists of an ultramafic unit, which is composed of lherzolite and olivine websterite, and a mafic unit, which is composed of olivine gabbronorite, gabbronorite and leuco-gabbronorite. This intrusion was formed by two separate pulses of magma: a more primitive magma for the early ultramafic unit and a more evolved magma for the late mafic unit. U-Pb isotope geochronology of zircon from the mafic unit yields an age of 278 ± 2 Ma. According to its olivine and Cr-rich spinel compositions, the estimated parental magma of lherzolite for the Huangshannan intrusion has 12.4 wt.% MgO, indicating picritic affinity. Fractional crystallization modeling results and the presence of rounded sulfide inclusions in an olivine crystal (Fo 86.7) indicate that sulfide immiscibility was achieved at the beginning of olivine fractionation. Co-magmatic zircon crystals from gabbronorite have a δ18O value close to 6.5‰, which is 1.2‰ higher than the typical mantle value and suggests significant crustal contamination (∼20%). The positive εHf(t) values of co-magmatic zircon (which vary from +9.2 to +15.3) and positive whole rock εNd(t) values (which vary from +4.7 to +7.8) also indicate that the parental magma was derived from a depleted mantle source and contaminated by 5-20% juvenile arc crust and then by ∼5% upper crustal materials. However, modeling results of sulfur content at sulfide saturation reveal that such a large amount of crustal contamination is not sufficient to trigger sulfide saturation in the parental magma, which strongly suggests that external sulfur addition, probably during contamination, has played a critical role in causing sulfide immiscibility. Furthermore, the arc magmatism geochemical signatures of the Huangshannan intrusion, such as significant Nb and Ta depletion relative to La and low Ca

  16. THE SULFIDATION/OXIDATION RESISTANCE OF TWO Ni-Cr-Al-Y ALLOYS AT 700℃

    Institute of Scientific and Technical Information of China (English)

    Y.X.Lu; W.X.Chen; R.Eadie

    2004-01-01

    The high temperature corrosion resistance of Ni-25.gCr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4 Cr-16.0A l-0.5 Y-0.2Hf alloys was assessed in sulfidation/oxidation environments.In the environment with a sulfur partial pressure of 1Pa.and an oxygen partial pressure of 10-19Pa,both these alloys exhibited three distinct stages in the weight gain-time curve when tested at 700℃.In the initial stage,selective sulfidation of Cr suppressed the formation of the other metal sulfides,resulting in lower weight gains.In the transient stage,breakdown and cracking of Cr sulfides and insufficient concentration of Cr at the outer zone led to the rapid formation of Ni sulfides and a rapid increase in weight.In the steady-state stage,corrosion was controlled by the diffusion of anions and/or cations,which led to a parabolic rate law.

  17. 230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

    Science.gov (United States)

    Yang, Weifang; Tao, Chunhui; Li, Huaiming; Liang, Jin; Liao, Shili; Long, Jiangping; Ma, Zhibang; Wang, Lisheng

    2016-11-01

    Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28'E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230Th/238U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

  18. Self-template synthesis of hollow ellipsoid Ni-Mn sulfides for supercapacitors, electrocatalytic oxidation of glucose and water treatment.

    Science.gov (United States)

    Cheng, Cheng; Kong, Dechen; Wei, Chengzhen; Du, Weimin; Zhao, Jianbo; Feng, Yeqin; Duan, Qingling

    2017-04-19

    In this work, we have successfully developed a simple self-template route for preparation of hollow ellipsoid Ni-Mn sulfides. This route involves the synthesis of solid Ni-Mn ellipsoids via a chemical precipitation method. Then, using thioacetamide (TAA) as the sulfur source, the solid Ni-Mn ellipsoids can be easily converted to hollow ellipsoid Ni-Mn sulfides in ethanol via sulfidation reaction. The as-synthesized hollow ellipsoid Ni-Mn sulfides possess large specific surface areas and porous structures. Benefiting from these structural and compositional advantages, the electrochemical performance of the hollow ellipsoid Ni-Mn sulfides is studied. As expected, the hollow ellipsoid Ni-Mn sulfides show a high specific capacitance of 1636.8 F g(-1) at 2.0 A g(-1) and good cycling stability (only 4.9% loss after 4000 cycles) as electrode materials for supercapacitors. Furthermore, electrocatalytic oxidation of glucose based on the synthesized hollow ellipsoid Ni-Mn sulfides is also performed. The hollow ellipsoid Ni-Mn sulfides present high sensitivity and selectivity, good stability and a low detection limit (0.02 μM). In addition, the as-synthesized hollow ellipsoid Ni-Mn sulfides exhibit good ability to remove the Congo red dyes from water, which gives them potential application in water treatment. The current work makes a major contribution to the design and preparation of hollow metal sulfide structures, as well as their potential applications in supercapacitors, electrocatalytic oxidation of glucose and water treatment.

  19. Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in Martian Meteorite ALH84001

    Science.gov (United States)

    Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.

    2006-01-01

    Magnetite and sulfides in the black rims of carbonate globules in Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the meteorite. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.

  20. Diet composition of roe deer (Capreolus capreolus in the Natural Park of the Garrotxa volcanic zone (Catalonia, Spain

    Directory of Open Access Journals (Sweden)

    Bartolomé, J.

    2002-12-01

    Full Text Available The present work outlines the results of a study on the food consumed by roe deer carried out in the Natural Park of the Garrotxa Volcanic Zone, where 49 roe deer were reintroduced from 1995 to 1998. This is a protected area of about 12,000 ha, in which oak and beech forests predominate. Faecal analysis was chosen as the most appropriate method for sampling diet composition despite the scarcity of faecal samples encountered from 1998 to 2001 (n=30. A total of 7,500 epidermal fragments were identified from these samples. Results showed that ivy (Hedera helix and bramble (Rubus sp. formed the bulk of the diet (23% and 21%, respectively. Woody species also formed an important part, reaching 33% of total fragments. Herbs and grasses were only notable in the spring-summer period. Some major vegetation components such as beech (Fagus sylvatica were rarely consumed by deer.

    [fr]
    Voici le résultat d'une étude sur l'alimentation du chevreuil dans le Parc Naturel de la Zone Volcanique de la Garrotxa, où 49 individus furent introduits entre 1995 et 1998. Il s'agit d'un espace protégé de 12 000 ha environ, dominé par les forêts de chênes et de hêtres. Malgré le nombre très bas d'excréments rencontrés entre 1998 et 2001 (n=30, leur analyse nous a paru la meilleure méthode pour tester la composition de l'alimentation. À partir de ces échantillons, nous avons identifié 7 500 fragments d'épiderme. Les résultats nous montrent que le lierre (Hedera helix et la ronce (Rubus sp. sont l'alimentation principale (23 et 21% respectivement. Toutefois, les espèces ligneuses sont également à considérer, puisqu'elles forment 33% des fragments totaux. Les herbes et les graminées s'avèrent importantes au cours du printemps-été. Il est à noter que les principaux composants de la végétation tel le hêtre (Fagus sylvatica étaient très rarement consommés.
    [es]
    Se exponen los

  1. Characterization of particulate organic matter in the Lena River Delta and adjacent nearshore zone, NE Siberia – Part 1: Lignin-derived phenol compositions

    Directory of Open Access Journals (Sweden)

    M. Winterfeld

    2014-10-01

    Full Text Available The Lena River in central Siberia is one of the major pathways translocating terrestrial organic matter (OM from its vast catchment area to the coastal zone of the Laptev Sea and the Arctic Ocean. The permafrost soils of its far south stretching catchment, which store huge amounts of OM, will most likely respond differently to climate warming and remobilize previously frozen OM with distinct properties specific for the source vegetation and soil. To characterize the material discharged by the Lena River, we analyzed the lignin phenol composition in total suspended matter (TSM from surface water collected in spring and summer, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene and third terraces (Pleistocene ice complex, and plant samples. Our results show that lignin-derived cinnamyl:vanillyl (C/V and syringyl:vanillyl (S/V ratios are >0.14 and 0.25, respectively, in TSM and surface sediments, whereas in delta soils they are >0.16 and >0.51, respectively. These lignin compositions are consistent with significant inputs of organic matter from non-woody angiosperm sources mixed with organic matter derived from woody gymnosperm sources. We applied a simple linear mixing model based on the C/V and S/V ratios and the results indicate the organic matter in delta TSM samples and Buor Khaya Bay surface sediments contain comparable contributions from gymnosperm material, which is primarily derived from the taiga forests south of the delta, and angiosperm material typical for tundra vegetation. Considering the small catchment area covered by tundra (∼12%, the input is substantial and tundra-derived OM input is likely to increase in a warming Arctic. The similar and high acid to aldehyde ratios of vanillyl and syringyl (Ad/AlV, S in Lena Delta summer TSM (>0.7 and >0.5, respectively and Buor Khaya Bay surface sediments (>1.0 and >0.9, respectively suggest that the OM is highly degraded and Lena River summer

  2. Durations Of Magma Storage And Mixing: The Record In Compositional Zoning Of Minerals And Its Connection To Surface Monitoring Data From Mt. Etna

    Science.gov (United States)

    Kahl, M.; Chakraborty, S.; Costa, F.

    2008-12-01

    Understanding the magmatic processes that occur within the plumbing systems of active volcanoes and the duration of magma storage beneath these are some of the main objectives of igneous petrology and volcanology. Over the past years, detailed petrological (e.g. thermobarometry) and geophysical (seismicity, ground deformation, microgravity etc.) work has considerably advanced our knowledge of the depth, size and shape of magma storage systems beneath volcanoes. Continuous monitoring provides time series data from the surface, but the actual processes involved in the dynamic evolution of the storage systems and their connection to the surface observations remain elusive. Temperature-dependent partitioning of elements, on which element exchange thermometry is based, combined with our knowledge of diffusion rates of the relevant elements allow us to model the continuous record stored in the compositional variations of minerals to access the dynamic evolution of plumbing systems. We have modeled the compositional zoning in olivine crystals from the eruptive products at Mt. Etna to study the time gap between intrusion of magma and their mixing at depth, and their eventual eruption at the surface. We consider data from the 1991/1993 eruptions, the two major flank eruptions in 2001 and 2002 and the very recent eruptive episodes in 2006 and 2007. We find that the time scales of magma mixing in this highly active and continually erupting system range between a few days and 2 years and that this interval has not varied significantly over the past two decades. Eruptive products fed by different plumbing systems (e.g. some 2001 and 2002 eruptions) are characterized by different time scales. This may provide a means of identifying different plumbing systems in historic eruptive products. Our inferences on timing of magma intrusion and movement at depth for the 1991/1993 period correlate well with real time monitoring data from the surface (seismicity, ground deformation, gas

  3. Modulation of calcium oxalate dihydrate growth by selective crystal-face binding of phosphorylated osteopontin and polyaspartate peptide showing occlusion by sectoral (compositional) zoning.

    Science.gov (United States)

    Chien, Yung-Ching; Masica, David L; Gray, Jeffrey J; Nguyen, Sarah; Vali, Hojatollah; McKee, Marc D

    2009-08-28

    Calcium oxalate dihydrate (COD) mineral and the urinary protein osteopontin/uropontin (OPN) are commonly found in kidney stones. To investigate the effects of OPN on COD growth, COD crystals were grown with phosphorylated OPN or a polyaspartic acid-rich peptide of OPN (DDLDDDDD, poly-Asp(86-93)). Crystals grown with OPN showed increased dimensions of the {110} prismatic faces attributable to selective inhibition at this crystallographic face. At high concentrations of OPN, elongated crystals with dominant {110} faces were produced, often with intergrown, interpenetrating twin crystals. Poly-Asp(86-93) dose-dependently elongated crystal morphology along the {110} faces in a manner similar to OPN. In crystal growth studies using fluorescently tagged poly-Asp(86-93) followed by imaging of crystal interiors using confocal microscopy, sectoral (compositional) zoning in COD was observed resulting from selective binding and incorporation (occlusion) of peptide exclusively into {110} crystal sectors. Computational modeling of poly-Asp(86-93) adsorption to COD {110} and {101} surfaces also suggests increased stabilization of the COD {110} surface and negligible change to the natively stable {101} surface. Ultrastructural, colloidal-gold immunolocalization of OPN by transmission electron microscopy in human stones confirmed an intracrystalline distribution of OPN. In summary, OPN and its poly-Asp(86-93) sequence similarly affect COD mineral growth; the {110} crystallographic faces become enhanced and dominant attributable to {110} face inhibition by the protein/peptide, and peptides can incorporate into the mineral phase. We, thus, conclude that the poly-Asp(86-93) domain is central to the OPN ability to interact with the {110} faces of COD, where it binds to inhibit crystal growth with subsequent intracrystalline incorporation (occlusion).

  4. Catalytic activity of in situ synthesized MoWNi sulfides in hydrogenation of aromatic hydrocarbons

    Science.gov (United States)

    Topolyuk, Yu. A.; Maksimov, A. L.; Kolyagin, Yu. G.

    2017-02-01

    MoWNi-sulfide catalysts were obtained in situ by thermal decomposition of metal-polymer precursors based on the copolymers of polymaleic anhydride in a hydrocarbon raw material. The activity of the synthesized catalysts in hydrogenation of bicyclic aromatic hydrocarbons was studied, and the composition and structure of active phase nanoparticles were determined.

  5. Embedding of colloidal Cadmium sulfide nanoparticles into poly-methylmetacrylate matrix

    OpenAIRE

    M. Bissengaliyeva; M. Zhukush; Irina Irgibayeva

    2012-01-01

    The technique of synthesis of polymethylmethacrylate – cadmium sulfide nanocomposites involving precipitation of CdS nanoparticles from polymethylmethacrylate solution in methylmethacrylate monomer with its subsequent polymerization is presented. A difference between the spectral-luminescent properties of the surface composite layer and the nanomaterial bulk, connected with redistribution of particles with higher degree of imperfection closer to the surface during polymerization is revealed.

  6. Formation of Submicron Copper Sulfide Particles Using Spray Pyrolysis Method

    Science.gov (United States)

    Lenggoro, I.; Kang, Yun; Komiya, Takafumi; Okuyama, Kikuo; Tohge, Noboru

    1998-03-01

    The morphology and crystalline phase of submicron copper sulfide particles prepared by spray pyrolysis method have been studied. In a nitrogen gas atmosphere, the covellite phase (CuS) spherical particles could be prepared using the solution with molar ratio of copper nitrate to thiourea and furnace temperatures of 1:2 at 200 300°C, as well as of 1:5 at 200 600°C. The crystalline phase of particles was highly depended on the composition of the precursors and the pyrolysis temperature. The sphericity of particles could be enhanced by increasing the temperature and prolonging the residence time of the droplets or particles in the furnace.

  7. Physical setting and characteristics of high-sulfidation epithermal gold-silver deposits of the Andes and controls on mineralizing processes

    Science.gov (United States)

    Bissig, T.

    2013-05-01

    Gold and silver mineralization in the vast majority of Andean high-sulfidation epithermal deposits occurs 200-700 m below low relief but high elevation landforms situated at 3500 to 5200 m a.s.l. Stratovolcanoes, in contrast, are uncommon ore hosts. Most deposits are middle Miocene and younger and include the California-Vetas mining district ( Colombia), Quimsaocha (Ecuador), Yanacocha, Lagunas Norte, Pierina, Cerro de Pasco (Peru), Pascua-Lama, Veladero, El Indio and Tambo (Chile/Argentina), jointly accounting for > 130 Moz Au resources. Older examples are restricted to the Atacama Desert and include the middle Eocene El Guanaco and El Hueso and the late Oligocene La Coipa deposits. Mineralization coincides with transpressional tectonics and surface uplift. Volcanic rocks coincident with mineralization are volumetrically restricted or absent, although dacitic domes are important at, e.g., Yanacocha, Lagunas Norte and La Coipa. Mineralization is typically located near the backscarps of pediments or heads of valleys incising into the high-elevation, low relief surfaces. In the California-Vetas district and El Indio belt, hydrothermal alunite ages become generally younger upstream along the incising valleys, indicating that the focus of mineralization migrated upstream over time. The lowering of the water table and reduction of hydrostatic and lithostatic pressure at locations where erosion rates are highest are believed to facilitate boiling and mixing of magmatic with meteoric fluids, ultimately enhancing hydrothermal activity and ore deposition. The host rock composition, permeability and location of the water table control the distribution of alteration zones and ore. The surface near steam-heated zone can attain a thickness of several hundred meters in dry climates but is typically less than 20-50 m thick in humid climatic zones. Felsic to intermediate volcanic rocks are the most common ore-hosts but high-sulfidation epithermal mineralization can be hosted in

  8. Composites

    Science.gov (United States)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  9. 21 CFR 177.2490 - Polyphenylene sulfide resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyphenylene sulfide resins. 177.2490 Section 177... Components of Articles Intended for Repeated Use § 177.2490 Polyphenylene sulfide resins. Polyphenylene sulfide resins (poly(1,4-phenylene sulfide) resins) may be safely used as coatings or components...

  10. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Energy Technology Data Exchange (ETDEWEB)

    Osuntokun, Jejenija; Ajibade, Peter A., E-mail: pajibade@ufh.ac.za

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato–κS,S’–bis (N,N-dimethylthiourea–κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33–7.21 nm for ZnS and 4.95–7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  11. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Science.gov (United States)

    Osuntokun, Jejenija; Ajibade, Peter A.

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato-κS,S'-bis(N,N-dimethylthiourea-κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33-7.21 nm for ZnS and 4.95-7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  12. Adequate hydrogen sulfide, healthy circulation

    Institute of Scientific and Technical Information of China (English)

    DU Jun-bao; CHEN Stella; JIN Hong-fang; TANG Chao-shu

    2011-01-01

    Previously,hydrogen sulfide (H2S) was considered to be a toxic gas.However,recently it was discovered that it could be produced in mammals and even in plants,throughtheproductionandmetabolismof sulfur-containing amino acids.In mammals,H2S is mainly catalyzed by cystathionine-γ-lyase (CSE),cystathionin-β-lyase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) with the substrate of L-cysteine.Endogenous H2S exerts many important physiological and pathophysiological functions,including hypotensive action,vasorelaxation,myocardial dilation,inhibition of smooth muscle cell proliferation,and antioxidatve actions.Importantly,it plays a very important role in the pathogenesis of systemic hypertension,pulmonary hypertension,atherosclerosis,myocardialinjury,angiogenesis,hyperhomocysteinemi aandshock.Therefore,H2S is now being considered to be a novel gasotransmitter after nitric oxide and carbon monoxide in the regulation of circulatory system.

  13. Redox biochemistry of hydrogen sulfide.

    Science.gov (United States)

    Kabil, Omer; Banerjee, Ruma

    2010-07-16

    H(2)S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of gamma-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H(2)S production in the vasculature. However, patients with inherited deficiency in gamma-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxidative phosphorylation while also exposing cytochrome c oxidase to this metabolic poison. This report focuses on the biochemistry of H(2)S biogenesis and clearance, on the molecular mechanisms of its action, and on its varied biological effects.

  14. Molybdenum evidence for expansive sulfidic water masses in ~ 750 Ma oceans

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Canfield, Donald Eugene; Rosing, Minik Thorleif

    2011-01-01

    composition of ancient seawater. Further, we investigate the ~ 750 Ma Walcott Member of the Chuar Group, Grand Canyon, which accumulated in a rift basin with open connection to the ocean. Iron speciation data from upper Walcott shales indicate that local bottom waters were anoxic and sulfidic, consistent......-Neoproterozoic oceans, bridging a nearly 700 million-year gap in previous Mo data. We propose that anoxic and sulfidic (euxinic) conditions governed Mo cycling in the oceans even as ferruginous subsurface waters re-appeared 800–750 Ma, and we interpret this anoxic ocean state to reflect a markedly lower atmospheric...

  15. Microbial control of hydrogen sulfide production

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J. [Univ. of Oklahoma, Tulsa, OK (United States)] [and others

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  16. Effect of nitrite and nitrate on in situ sulfide production in an activated sludge immobilized agar gel film as determined by use of microelectrodes.

    Science.gov (United States)

    Okabe, Satoshi; Santegoeds, Cecilia M; De Beer, Dirk

    2003-03-01

    Microelectrode, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) analyses were used to investigate the effect of nitrite and nitrate on in situ sulfide production in an activated sludge immobilized agar gel film. Microelectrode measurements of O(2), H(2)S, NO(3)(-), NO(2)(-), and pH revealed that the addition of NO(2)(-) and NO(3)(-) forced sulfate reduction zones deeper in the agar gel and significantly reduced the in situ sulfide production levels. The sulfate reduction zone was consequently separated from O(2) and NO(2)(-) or NO(3)(-) respiration zones with increasing the concentrations of NO(2)(-) and NO(3)(-). These NO(2)(-) and NO(3)(-) treatments had only a transient effect on sulfide production. The in situ sulfide production quickly recovered to the previous levels when NO(2)(-) and NO(3)(-) were removed. The PCR-DGGE and FISH analyses revealed that 2-day-continuous addition of 500 microM NO(3)(-) did not change the metabolically active sulfate-reducing bacterial (SRB) community. On the basis of these data, it could be concluded that the addition of NO(2)(-) and NO(3)(-) did not kill SRB, but induced the interspecies competition for common carbon source (i.e., acetate) between nitrate-reducing heterotrophic bacteria and SRB and enhanced the oxidation of the produced sulfide, which were main possible causes of the suppression of in situ sulfide production in the agar gel.

  17. Structural studies in limestone sulfidation

    Energy Technology Data Exchange (ETDEWEB)

    Fenouil, Laurent A. [Univ. of California, Berkeley, CA (United States)

    1993-05-01

    This study investigates the sulfidation of limestone at high temperatures (700--900°C) as the first step in the design of a High-Temperature Coal-Gas Clean-Up system using millimeter-size limestone particles. Several workers have found that the rate of this reaction significantly decreases after an initial 10 to 15% conversion of CaCO3 to CaS. The present work attempts to explain this feature. It is first established that millimeter-size limestone particles do not sinter at temperatures up to the CaCO3 calcination point (899°C at 1.03 bar CO2} partial pressure). It is then shown that CaS sinters rapidly at 750 to 900°C if CO2 is present in the gas phase. Scanning Electron Microscope (SEM) photographs and Electron Dispersive Spectroscopy (EDS) data reveal that the CaS product layer sinters and forms a quasi-impermeable coating around the CaCO3 grains that greatly hinders more H2S from reaching the still unreacted parts of the stone. Moreover, most of the pores initially present within the limestone structure begin to disappear or, at least, are significantly reduced in size. From then on, subsequent conversion is limited by diffusion of H2S through the CaS layer, possibly by S2- ionic diffusion. The kinetics is then adequately described by a shrinking-core model, in which a sharp front of completely converted limestone is assumed to progress toward the center of the pellet. Finally, experimental evidence and computer simulations using simple sintering models suggest that the CaS sintering, responsible for the sharp decrease in the sulfidation rate, is surface-diffusion controlled.

  18. Silicate sulfidation and chemical differences between enstatite chondrites and Earth

    Science.gov (United States)

    Lehner, S. W.; Petaev, M. I.; Buseck, P. R.

    2013-12-01

    Isotopic similarity between the Earth-Moon system and enstatite chondrites (ECs) led to the idea that ECs were Earth's building blocks [1-3]. However, compared to Earth's mantle, ECs have low Fe0/Fe ratios, are enriched in volatile elements, and depleted in refractory lithophile elements and Mg [4]. Therefore, deriving Earth composition from ECs requires a loss of volatiles during or prior to accretion and sequestering a large fraction of Si in the deep Earth. Alternatively, the isotopic similarity between the Earth and ECs is explained by their formation from a common precursor that experienced different evolutionary paths resulting in the chemical difference [4]. The vestiges of such a precursor are still present in the unequilibrated ECs as FeO-rich silicates with O isotopic compositions identical to bulk ECs and Earth [5]. Conversion of such a precursor into the characteristic EC mineral assemblage requires high-temperature processing in an H-poor environment with high fS2 and fO2 close to that of the classic solar nebula [6], consistent with redox conditions inferred from Ti4+/Ti3+ ratios in EC pyroxene [7]. Under such conditions reaction of FeO-rich silicates with S-rich gas results in their replacement by the assemblage of FeO-poor silicates; Fe, Mg, Ca sulfides; free silica; and Si-bearing Fe,Ni metal alloy. The progressive sulfidation of ferromagnesian silicates in chondrules results in loss of Mg and addition of Fe, Mn, S, Na, K and, perhaps, other volatiles [6]. At the advanced stages of silicate sulfidation recorded in the metal-sulfide nodules [8], a portion of Si is reduced and dissolved in the Fe,Ni metal. This process is known to fractionate Si isotopes [9,10] and would explain the differences between the ECs and Earth's mantle [11]. The sulfidation of silicates also produces porous S-rich silica, a peculiar phase observed so far only in the ECs. It consists of a sinewy SiO2-rich framework enclosing numerous vesicles filled with beam

  19. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    OpenAIRE

    Klatt, Judith M.; Al-Najjar, Mohammad A. A.; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39,...

  20. Removal of methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide from contaminated air by Thiobacillus thioparus TK-m.

    OpenAIRE

    Kanagawa, T; Mikami, E.

    1989-01-01

    Methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide were efficiently removed from contaminated air by Thiobacillus thioparus TK-m and oxidized to sulfate stoichiometrically. More than 99.99% of dimethyl sulfide was removed when the load was less than 4.0 g of dimethyl sulfide per g (dry cell weight) per day.

  1. Hydrogen Sulfide Induces Oxidative Damage to RNA and DNA in a Sulfide-Tolerant Marine Invertebrate

    OpenAIRE

    Joyner-Matos, Joanna; Predmore, Benjamin L.; Stein, Jenny R.; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes ...

  2. Oxygen and sulfur isotope fractionation during sulfide oxidation by anoxygenic phototrophic bacteria

    Science.gov (United States)

    Brabec, Michelle Y.; Lyons, Timothy W.; Mandernack, Kevin W.

    2012-04-01

    Sulfide-mediated anoxygenic photosynthesis (SMAP) carried out by anaerobic phototrophic bacteria may have played an important role in sulfur cycling, formation of sulfate, and, perhaps, primary production in the Earth’s early oceans. Determination of ε34SSO4-Sulfide- and ε18OSO4-H2O values for bacterial sulfide oxidation will permit more refined interpretation of the δ34S and δ18OSO4 values measured in modern anoxic environments, such as meromictic lakes where sulfide commonly extends into the photic zone, and in the ancient rock record, particularly during periods of the Precambrian when anoxic and sulfidic (euxinic) conditions were believed to be more pervasive than today. Laboratory experiments with anaerobic purple and green sulfur phototrophs, Allochromatium vinosum and Chlorobaculum tepidum, respectively, were conducted to determine the sulfur and oxygen isotope fractionation during the oxidation of sulfide to sulfate. Replicate experiments were conducted at 25 °C for A. vinosum and 45 °C for C. tepidum, and in duplicate at three different starting oxygen isotope values for water to determine sulfate-water oxygen isotope fractionations accurately (ε18OSO4-H2O). ε18OSO4-H2O values of 5.6 ± 0.2‰ and 5.4 ± 0.1‰ were obtained for A. vinosum and C. tepidum, respectively. Temperature had no apparent effect on the ε18OSO4-H2O values. By combining all data from both cultures, an average ε18OSO4-H2O value of 5.6 ± 0.3‰ was obtained for SMAP. This value falls between those previously reported for bacterial oxidation of sphalerite and elemental sulfur (7-9‰) and abiotic and biotic oxidation of pyrite and chalcopyrite (2-4‰). Sulfur isotope fractionation between sulfide and sulfate formed by A.vinosum was negligible (0.1 ± 0.2‰) during all experiments. For C. tepidum an apparent fractionation of -2.3 ± 0.5‰ was observed during the earlier stages of oxidation based on bulk δ34S measurements of sulfate and sulfide and became smaller (-0.7

  3. Ecological release and niche partitioning under stress: Lessons from dorvilleid polychaetes in sulfidic sediments at methane seeps

    Science.gov (United States)

    Levin, Lisa A.; Ziebis, Wiebke; Mendoza, Guillermo F.; Bertics, Victoria J.; Washington, Tracy; Gonzalez, Jennifer; Thurber, Andrew R.; Ebbe, Brigitte; Lee, Raymond W.

    2013-08-01

    assemblages (measured by Total Hull Area and Standard Elliptical Area using species averages) and functional redundancy or species packing (measured as distance to nearest neighbor) among species and individuals were generally higher at ER, where sulfide levels were lower than at HR. In contrast, average trophic diversity among individuals within a species was greater at HR than ER. In colonization experiments involving agar-based manipulations of sulfide in tray sediments that mimicked clam bed and mat conditions, dorvilleids comprised 68% and 48% of colonists at ER and HR, respectively. Dorvilleid species richness was higher in trays that were initially more sulfidic. However, habitat exerted stronger influence on the composition of colonizing dorvilleids than did sulfide additions. In the NE Pacific, regional, habitat and vertical (down-core) variation in hydrogen sulfide creates complex environmental heterogeneity at methane seeps, promoting high diversity of stress-tolerant taxa such as dorvilleid polychaetes.

  4. Oxidative Weathering and Microbial Diversity of an Inactive Seafloor Hydrothermal Sulfide Chimney.

    Science.gov (United States)

    Li, Jiangtao; Cui, Jiamei; Yang, Qunhui; Cui, Guojie; Wei, Bingbing; Wu, Zijun; Wang, Yong; Zhou, Huaiyang

    2017-01-01

    When its hydrothermal supply ceases, hydrothermal sulfide chimneys become inactive and commonly experience oxidative weathering on the seafloor. However, little is known about the oxidative weathering of inactive sulfide chimneys, nor about associated microbial community structures and their succession during this weathering process. In this work, an inactive sulfide chimney and a young chimney in the early sulfate stage of formation were collected from the Main Endeavor Field of the Juan de Fuca Ridge. To assess oxidative weathering, the ultrastructures of secondary alteration products accumulating on the chimney surface were examined and the presence of possible Fe-oxidizing bacteria (FeOB) was investigated. The results of ultrastructure observation revealed that FeOB-associated ultrastructures with indicative morphologies were abundantly present. Iron oxidizers primarily consisted of members closely related to Gallionella spp. and Mariprofundus spp., indicating Fe-oxidizing species likely promote the oxidative weathering of inactive sulfide chimneys. Abiotic accumulation of Fe-rich substances further indicates that oxidative weathering is a complex, dynamic process, alternately controlled by FeOB and by abiotic oxidization. Although hydrothermal fluid flow had ceased, inactive chimneys still accommodate an abundant and diverse microbiome whose microbial composition and metabolic potential dramatically differ from their counterparts at active vents. Bacterial lineages within current inactive chimney are dominated by members of α-, δ-, and γ-Proteobacteria and they are deduced to be closely involved in a diverse set of geochemical processes including iron oxidation, nitrogen fixation, ammonia oxidation and denitrification. At last, by examining microbial communities within hydrothermal chimneys at different formation stages, a general microbial community succession can be deduced from early formation stages of a sulfate chimney to actively mature sulfide

  5. Catalysis of Dissolved and Adsorbed Iron in Soil Suspension for Chromium(Ⅵ) Reduction by Sulfide

    Institute of Scientific and Technical Information of China (English)

    LAN Ye-Qing; YANG Jun-Xiang; B. DENG

    2006-01-01

    The kinetics of Cr(Ⅵ) reduction by sulfide in soil suspensions with various pHs, soil compositions, and Fe(Ⅱ) concentrations was examined using batch anaerobic experimental systems at constant temperature. The results showed that the reaction rate of Cr(Ⅵ) reduction was in the order of red soil < yellow-brown soil < chernozem and was proportional to the concentration of HCl-extractable iron in the soils. Dissolved and adsorbed iron in soil suspensions played an important role in accelerating Cr(Ⅵ) reduction. The reaction involved in the Cr(Ⅵ) reduction by Fe(Ⅱ) to produce Fe(Ⅲ), which was reduced to Fe(Ⅱ) again by sulfide, could represent the catalytic pathway until about 70% of the initially present Cr(Ⅵ)was reduced. The catalysis occurred because the one-step reduction of Cr(Ⅵ) by sulfide was slower than the two-step process consisting of rapid Cr(Ⅵ) reduction by Fe(Ⅱ) followed by Fe(Ⅲ) reduction by sulfide. In essence, Fe(Ⅱ)/Fe(Ⅲ)species shuttle electrons from sulfide to Cr(Ⅵ), facilitating the reaction. The effect of iron, however, could be completely blocked by adding a strong Fe(Ⅱ)-complexing ligand, 1,10-phenanthroline, to the soil suspensions. In all the experiments,initial sulfide concentration was much higher than initial Cr(Ⅵ) concentration. The plots of ln c[Cr(Ⅵ)] versus reaction time were linear up to approximately 70% of Cr(Ⅵ) reduction, suggesting a first-order reaction kinetics with respect to Cr(Ⅵ). Elemental sulfur, the product of sulfide oxidation, was found to accelerate Cr(Ⅵ) reduction at a later stage of the reaction, resulting in deviation from linearity for the ln c[Cr(Ⅵ)] versus time plots.

  6. Adsorption of dimethyl sulfide from aqueous solution by a cost-effective bamboo charcoal.

    Science.gov (United States)

    Wang, Ming; Huang, Zheng-Hong; Liu, Guangjia; Kang, Feiyu

    2011-06-15

    The adsorption of dimethyl sulfide from an aqueous solution by a cost-effective bamboo charcoal from Dendrocalamus was studied in comparison with other carbon adsorbents. The bamboo charcoal exhibited superior adsorption on dimethyl sulfide compared with powdered activated carbons at different adsorbent dosages. The adsorption characteristics of dimethyl sulfide onto bamboo charcoal were investigated under varying experimental conditions such as particle size, contact time, initial concentration and adsorbent dosage. The dimethyl sulfide removal was enhanced from 31 to 63% as the particle size was decreased from 24-40 to >300 mesh for the bamboo charcoal. The removal efficiency increased with increasing the adsorbent dosage from 0.5 to 10mg, and reached 70% removal efficiency at 10mg adsorbed. The adsorption capacity (μg/g) increased with increasing concentration of dimethyl sulfide while the removal efficiency decreased. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of dimethyl sulfide is more appropriately described by the Freundlich isotherm (R(2), 0.9926) than by the Langmuir isotherm (R(2), 0.8685). Bamboo charcoal was characterized by various analytical methods to understand the adsorption mechanism. Bamboo charcoal is abundant in acidic and alcohol functional groups normally not observed in PAC. A distinct difference is that the superior mineral composition of Fe (0.4 wt%) and Mn (0.6 wt%) was detected in bamboo charcoal-elements not found in PAC. Acidic functional group and specific adsorption sites would be responsible for the strong adsorption of dimethyl sulfide onto bamboo charcoal of Dendrocalamus origin.

  7. Composites

    Science.gov (United States)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  8. Nitrate-reducing, sulfide-oxidizing bacteria as microbial oxidants for rapid biological sulfide removal.

    Science.gov (United States)

    De Gusseme, Bart; De Schryver, Peter; De Cooman, Michaël; Verbeken, Kim; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2009-01-01

    The emission of hydrogen sulfide into the atmosphere of sewer systems induces the biological production of sulfuric acid, causing severe concrete corrosion. As a possible preventive solution, a microbial consortium of nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) was enriched in a continuously stirred tank reactor in order to develop a biological technique for the removal of dissolved sulfide. The consortium, dominated by Arcobacter sp., was capable of removing 99% of sulfide. Stable isotope fractioning of the sulfide indicated that the oxidation was a biological process. The capacity of the NR-SOB consortium for rapid removal of sulfide was demonstrated by using it as an inoculum in synthetic and real sewage. Removal rates up to 52 mg sulfide-S g VSS(-1) h(-1) were achieved, to our knowledge the highest removal rate reported so far for freshwater species in the absence of molecular oxygen. Further long-term incubation experiments revealed the capacity of the bacteria to oxidize sulfide without the presence of nitrate, suggesting that an oxidized redox reserve is present in the culture.

  9. Alternative waste residue materials for passive in situ prevention of sulfide-mine tailings oxidation: a field evaluation.

    Science.gov (United States)

    Nason, Peter; Johnson, Raymond H; Neuschütz, Clara; Alakangas, Lena; Öhlander, Björn

    2014-02-28

    Novel solutions for sulfide-mine tailings remediation were evaluated in field-scale experiments on a former tailings repository in northern Sweden. Uncovered sulfide-tailings were compared to sewage-sludge biosolid amended tailings over 2 years. An application of a 0.2m single-layer sewage-sludge amendment was unsuccessful at preventing oxygen ingress to underlying tailings. It merely slowed the sulfide-oxidation rate by 20%. In addition, sludge-derived metals (Cu, Ni, Fe, and Zn) migrated and precipitated at the tailings-to-sludge interface. By using an additional 0.6m thick fly-ash sealing layer underlying the sewage sludge layer, a solution to mitigate oxygen transport to the underlying tailings and minimize sulfide-oxidation was found. The fly-ash acted as a hardened physical barrier that prevented oxygen diffusion and provided a trap for sludge-borne metals. Nevertheless, the biosolid application hampered the application, despite the advances in the effectiveness of the fly-ash layer, as sludge-borne nitrate leached through the cover system into the underlying tailings, oxidizing pyrite. This created a 0.3m deep oxidized zone in 6-years. This study highlights that using sewage sludge in unconventional cover systems is not always a practical solution for the remediation of sulfide-bearing mine tailings to mitigate against sulfide weathering and acid rock drainage formation. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Alternative waste residue materials for passive in situ prevention of sulfide-mine tailings oxidation: A field evaluation

    Science.gov (United States)

    Nason, Peter; Johnson, Raymond H.; Neuschutz, Clara; Alakangas, Lena; Ohlander, Bjorn

    2014-01-01

    Novel solutions for sulfide-mine tailings remediation were evaluated in field-scale experiments on a former tailings repository in northern Sweden. Uncovered sulfide-tailings were compared to sewage-sludge biosolid amended tailings over 2 years. An application of a 0.2 m single-layer sewage-sludge amendment was unsuccessful at preventing oxygen ingress to underlying tailings. It merely slowed the sulfide-oxidation rate by 20%. In addition, sludge-derived metals (Cu, Ni, Fe, and Zn) migrated and precipitated at the tailings-to-sludge interface. By using an additional 0.6 m thick fly-ash sealing layer underlying the sewage sludge layer, a solution to mitigate oxygen transport to the underlying tailings and minimize sulfide-oxidation was found. The fly-ash acted as a hardened physical barrier that prevented oxygen diffusion and provided a trap for sludge-borne metals. Nevertheless, the biosolid application hampered the application, despite the advances in the effectiveness of the fly-ash layer, as sludge-borne nitrate leached through the cover system into the underlying tailings, oxidizing pyrite. This created a 0.3 m deep oxidized zone in 6-years. This study highlights that using sewage sludge in unconventional cover systems is not always a practical solution for the remediation of sulfide-bearing mine tailings to mitigate against sulfide weathering and acid rock drainage formation.

  11. The Effect of Oxygen Potential on the Sulfide Capacity for Slags Containing Multivalent Species

    Science.gov (United States)

    Allertz, Carl; Selleby, Malin; Sichen, Du

    2016-10-01

    The dependence of sulfide capacity on the oxygen partial pressure for slags containing multivalent species was investigated experimentally using a slag containing vanadium oxide. Copper-slag equilibration experiments were carried out at 1873 K (1600 °C) in the approximate oxygen partial pressure range 10-15.4 to 10-9 atm. The sulfide capacity was found to be strongly dependent on the oxygen potential in this slag system, increasing with the oxygen partial pressure. The sulfide capacity changed by more than two orders of magnitude over the oxygen partial pressure range. The effect of changing oxygen partial pressure was found to be much greater than the effect of changing slag composition at a fixed oxygen partial pressure.

  12. Precise tuning in platinum-nickel/nickel sulfide interface nanowires for synergistic hydrogen evolution catalysis

    Science.gov (United States)

    Wang, Pengtang; Zhang, Xu; Zhang, Jin; Wan, Sheng; Guo, Shaojun; Lu, Gang; Yao, Jianlin; Huang, Xiaoqing

    2017-01-01

    Comprising abundant interfaces, multicomponent heterostructures can integrate distinct building blocks into single entities and yield exceptional functionalities enabled by the synergistic components. Here we report an efficient approach to construct one-dimensional metal/sulfide heterostructures by directly sulfuring highly composition-segregated platinum-nickel nanowires. The heterostructures possess a high density of interfaces between platinum-nickel and nickel sulfide components, which cooperate synergistically towards alkaline hydrogen evolution reaction. The platinum-nickel/nickel sulfide heterostructures can deliver a current density of 37.2 mA cm−2 at an overpotential of 70 mV, which is 9.7 times higher than that of commercial Pt/C. The heterostructures also offer enhanced stability revealed by long-term chronopotentiometry measurements. The present work highlights a potentially powerful interface-engineering strategy for designing multicomponent heterostructures with advanced performance in hydrogen evolution reaction and beyond. PMID:28239145

  13. [Biooxidation of a Double-Refractory Gold-Bearing Sulfide Ore Concentrate].

    Science.gov (United States)

    Bulaev, A G; Kanaeva, Z K; Kanaev, A T; Kondrat'eva, T F

    2015-01-01

    The efficiency of biooxidation for treatment of a double-refractory gold-bearing sulfide ore concentrate from the Bakyrchik deposit (East Kazakhstan) was defined. The experiments were conducted in two different modes, i.e., with the standard liquid medium and the medium imitating the chemical composition of the Bakyrchik deposit groundwater and containing high concentrations of sodium, magnesium, and chloride. The concentrate contained 17.5% of organic carbon, 6% of pyrite and 13% arsenopyrite. Gold content was 57.5 g t@-1@. Direct gold recovery by cyanidation was very low (2.8%). While biooxidation was efficient in both cases (approximately 90% of sulfide sulfur was oxidized), the efficiency of cyanidation was low (39 and 32%, respectively). This fact suggests high efficiency of biooxidation is insufficient for efficient treatment of double-refractory gold-bearing sulfide ore concentrates.

  14. Understanding hydrodenitrogenation on novel unsupported sulfide Mo-W-Ni catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hein, J.; Hrabar, A.; Gutierrez, O.Y.; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

    2011-07-01

    WNi, NiMo and Mo-W-Ni unsupported catalysts were synthesized, characterized and tested with respect to their hydrodenitrogenation properties using o-propylaniline as test reactant. The bimetallic oxide precursors are crystalline metallates, whereas the trimetallic materials are amorphous. In the sulfide form, the catalysts are mixtures of agglomerated Mo(W)S{sub 2} and Ni sulfides. The performance of all catalysts is similar, suggesting the same nature of active sites regardless the composition. Due to the lack of correlation between activity and density of coordinatively unsaturated sites of the catalysts, two kinds of active sites are proposed, i.e. coordinatively unsaturated sites and electron rich sites at the edges of the sulfides. (orig.)

  15. [Fatal outcome of an hydrogen sulfide poisoning].

    Science.gov (United States)

    Querellou, E; Jaffrelot, M; Savary, D; Savry, C; Perfus, J-P

    2005-10-01

    We report a case of fatal outcome poisoning by massive exposure to hydrogen sulfide of a sewer worker. This rare event was associated with a moderate intoxication of two members of the rescue team. The death was due to asystole and massive lung oedema. Autopsy analysis showed diffuse necrotic lesions in lungs. Hydrogen sulfide is a direct and systemic poison, produced by organic matter decomposition. The direct toxicity mechanism is still unclear. The systemic toxicity is due to an acute toxicity by oxygen depletion at cellular level. It is highly diffusable and potentially very dangerous. At low concentration, rotten egg smell must trigger hydrogen sulfide suspicion since at higher concentration it is undetectable, making intoxication possible. In case of acute intoxication, there is an almost instantaneous cardiovascular failure and a rapid death. Hydrogen sulfide exposure requires prevention measures and more specifically the use of respiratory equipment for members of the rescue team.

  16. Hydrogen sulfide in hemostasis: friend or foe?

    Science.gov (United States)

    Olas, Beata

    2014-06-25

    Hydrogen sulfide (H2S) is a well known toxic gas that is synthesized from the amino acids: cysteine (Cys) and homocysteine (Hcy) by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and mercaptopyruvate sulfurtransferase (3-MST). Hydrogen sulfide, like carbon monoxide (CO) or nitric oxide (NO) is a signaling molecule in different biological systems, including the cardiovascular system. Moreover, hydrogen sulfide plays a role in the pathogenesis of various cardiovascular diseases. It modulates different elements of hemostasis (activation of blood platelet, and coagulation process) as well as proliferation and apoptosis of vascular smooth muscle cells. However, the biological role and the therapeutic potential of H2S is not clear. This review summarizes the different functions of hydrogen sulfide in hemostasis.

  17. Localized sulfate-reducing zones in a coastal plain aquifer

    Science.gov (United States)

    Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

    1999-01-01

    High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

  18. Relationships between microbial communities and environmental parameters at sites impacted by mining of volcanogenic massive sulfide deposits, Prince William Sound, Alaska

    Science.gov (United States)

    Foster, A.L.; Munk, L.; Koski, R.A.; Shanks, Wayne C.; Stillings, L.L.

    2008-01-01

    produced a very different sample arrangement. Specifically, the sediment parameter PCA grouped samples with high bulk trace metal concentration regardless of whether the metals were incorporated into secondary precipitates or primary sulfides. The water chemistry PCA and FAMEs PCA appear to be less prone to this type of artifact. Signature lipids in sulfide-rich sediments could indicate the presence of acid-tolerant and/or acidophilic members of the genus Thiobacillus or they could indicate the presence of SO4-reducing bacteria. The microbial community documented in subtidal and offshore sediments is rich in SRB and/or facultative anaerobes of the Cytophaga-Flavobacterium group; both could reasonably be expected in PWS coastal environments. The results of this study provide evidence for substantial feedback between local (meter to centimeter-scale) geochemical variations, and sediment microbial community composition, and show that microbial community signatures in the intertidal zone are significantly altered at sites where ARD drainage is present relative to sites where it is not, even if the sediment geochemistry indicates net accumulation of ARD-generated trace metals in the intertidal zone. ?? 2007 Elsevier Ltd. All rights reserved.

  19. Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127°04.5′E, 27°15′N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the 210Pb radioactivity ratios and 210Pb/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the 210Pb/Pb ratios of hydrothermal sulfide samples (3.99×10-5-5.42×10?5), their U isotopic composition (238U content 1.15-2.53 ppm, 238U activity 1.07-1.87 dpm/g, 234U activity 1.15-2.09 dpm/g and 234U/238U ratio 1.07-1.14) and their 232Th and 230Th contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

  20. Thermodynamic Model and Database for Sulfides Dissolved in Molten Oxide Slags

    Science.gov (United States)

    Kang, Youn-Bae; Pelton, Arthur D.

    2009-12-01

    A thermodynamic model has been developed in the framework of the modified quasichemical model in the quadruplet approximation to permit the calculation of solubilities of various gaseous species (sulfide, sulfate, nitride, carbide, water, etc.) in molten slags. The model calculates the solubilities solely from knowledge of the thermodynamic activities of the component oxides and the Gibbs energies of the pure liquid components (oxides, sulfides, sulfates, etc.). In the current article, it is shown that solubilities of sulfur as sulfide in Al2O3-CaO-FeO-Fe2O3-MgO-MnO-SiO2-TiO2-Ti2O3 multicomponent slags, which are predicted from the current model with no adjustable model parameters, are in good agreement with all available experimental data. The article also provides a thorough review of experimental sulfide capacity data for this system. The model applies at all compositions from pure oxides to pure sulfides and from basic to acidic slags. By coupling this database with other evaluated databases, such as those for molten metal and gaseous phases, and with general software for Gibbs energy minimization, practically important slag/metal/gas/solid equilibria can be computed such as S-distribution ratios.

  1. Nitrate stimulation of indigenous nitrate-reducing, sulfide-oxidising bacterial community in wastewater anaerobic biofilms.

    Science.gov (United States)

    Garcia-de-Lomas, Juan; Corzo, Alfonso; Carmen Portillo, M; Gonzalez, Juan M; Andrades, Jose A; Saiz-Jimenez, Cesáreo; Garcia-Robledo, Emilio

    2007-07-01

    The role of the nitrate-reducing, sulfide-oxidising bacteria (NR-SOB) in the nitrate-mediated inhibition of sulfide net production by anaerobic wastewater biofilms was analyzed in two experimental bioreactors, continuously fed with the primary effluent of a wastewater treatment plant, one used as control (BRC) and the other one supplemented with nitrate (BRN). This study integrated information from H(2)S and pH microelectrodes, RNA-based molecular techniques, and the time course of biofilm growth and bioreactors water phase. Biofilms were a net source of sulfide for the water phase (2.01 micromol S(2-)(tot)m(-2)s(-1)) in the absence of nitrate dosing. Nitrate addition effectively led to the cessation of sulfide release from biofilms despite which a low rate of net sulfate reduction activity (0.26 micromol S(2-)(tot)m(-2)s(-1)) persisted at a deep layer within the biofilm. Indigenous NR-SOB including Thiomicrospira denitrificans, Arcobacter sp., and Thiobacillus denitrificans were stimulated by nitrate addition resulting in the elimination of most sulfide from the biofilms. Active sulfate reducing bacteria (SRB) represented comparable fractions of total metabolically active bacteria in the libraries obtained from BRN and BRC. However, we detected changes in the taxonomic composition of the SRB community suggesting its adaptation to a higher level of NR-SOB activity in the presence of nitrate.

  2. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.

    2004-01-01

    The emissions process of hydrogen sulfide was studied to quantify air–water transfer of hydrogen sulfide in sewer networks. Hydrogen sulfide transfer across the air–water interface was investigated at different turbulence levels (expressed in terms of the Froude number) and pH using batch...... experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...

  3. Mechanism of mechanical activation for sulfide ores

    Institute of Scientific and Technical Information of China (English)

    HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun

    2007-01-01

    Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.

  4. Sulfide as a soil phytotoxin - A review

    Directory of Open Access Journals (Sweden)

    Leon P M Lamers

    2013-07-01

    Full Text Available In wetland soils and underwater sediments of marine, brackish and freshwater systems, the strong phytotoxin sulfide may accumulate as a result of microbial reduction of sulfate during anaerobiosis, its level depending on prevailing edaphic conditions. In this review, we compare an extensive body of literature on phytotoxic effects of this reduced sulfur compound in different ecosystem types, and review the effects of sulfide at multiple ecosystem levels: the ecophysiological functioning of individual plants, plant-microbe associations, and community effects including competition and facilitation interactions. Recent publications on multi-species interactions in the rhizosphere show even more complex mechanisms explaining sulfide resistance. It is concluded that sulfide is a potent phytotoxin, profoundly affecting plant fitness and ecosystem functioning in the full range of wetland types including coastal systems, and at several levels. Traditional toxicity testing including hydroponic approaches generally neglect rhizospheric effects, which makes it difficult to extrapolate results to real ecosystem processes. To explain the differential effects of sulfide at the different organizational levels, profound knowledge about the biogeochemical, plant physiological and ecological rhizosphere processes is vital. This information is even more important, as anthropogenic inputs of sulfur into freshwater ecosystems and organic loads into freshwater and marine systems are still much higher than natural levels, and are steeply increasing in Asia. In addition, higher temperatures as a result of global climate change may lead to higher sulfide production rates in shallow waters.

  5. Vesicle-metal-sulfide assemblages from the Chelyabinsk meteorite

    Science.gov (United States)

    Andronikov, A.; Lauretta, D.; Hill, D.; Andronikova, I.

    2014-07-01

    On February 15, 2013, an ET object entered the Earth's atmosphere over the Russian city of Chelyabinsk. It entered at a preatmospheric velocity of 18.6 km/sec at the angle of 17--20°. The bolide responsible for this event was estimated to be 17-20 m in diameter and had a mass of ˜10 Ktons; the ensuing airburst occurred at an altitude >20 km and released a total energy of ˜440 kT [1,2]. The Chelyabinsk meteorite is an equilibrated LL5 ordinary chondrite, shock stage S4, and weathering grade WG0 similar to other LL5 falls [1,2]. Our studied sample is an impact melt breccia consisting of shock-darkened chondrite clasts (SDC) and vesicular impact melt lithology (IML). The SDC have recrystallized textures and contain barred- and porphyritic-olivine, porphyritic-olivine-pyroxene and radial-pyroxene chondrules in the intrachondrule matrix. A dense network of thin fractures in the SDC is filled up with opaque minerals [cf. 3]. Metals in the SDC are kamacite (4.7--8.5 % Ni), taenite (21.4--33.5 % Ni), and martensite (14.5--18.6 % Ni). The IML consists mostly of tiny (bearing troilite (62.2--64.2 % Fe; 35.2--37.2 % S; 3000--5000 ppm Ni), with rare pentlandite (41.2--48.6 % Fe, 33.2--34.3 % S, 19.4--23.9 % Ni). The presence of abundant vesicles in the IML indicates strong heating and volatilization. Since no other phase except for sulfide-metal assemblages were observed to fill up vesicles, the likely source of volatiles is S vapor formed by vaporization of FeS during impact melting [cf. 4]. Molten metal and sulfide coalesced into droplets of metal-sulfide liquids forming eventually sulfide-metal assemblages. A notable compositional difference is observed between sulfides not containing metals and those with metals. The metal-free sulfides display higher concentrations of such elements as Ni, Co, Ga, Ge, As, Mo, Ru, Pd, Sn, Sb, Te, Au, and Hg, and lower amounts of Cu than their metal-bearing counterparts. The metal-free sulfides may represent loci of former ''parental'' Fe

  6. 复合处理技术在硫化物自润滑薄膜制备中的应用%Applications of the Composite Processing Technology in the Preparation of Sulfide Self-lubricating Film

    Institute of Scientific and Technical Information of China (English)

    张蒙科; 韩彬

    2014-01-01

    Sulfurizing layer can effectively decrease the coefficient of friction, improve the anti-scratch properties and wear re-sistance of the parts, but solely low-temperature ion sulphurization cannot guarantee to meet the production requirements of specific conditions, the composite processing method of other technologies and low-temperature ion sulfurization result in ideal solid self-lu-bricating coating with soft surface and hard subsurface, which meets the needs of the production environment. This paper reviewed the characteristics and part of the research instances for the ion multiple composite infiltration method ( S-N, S-C-N, S-O, S-Mo) , two-step method ( shot peening processing, supersonic nanocrystallization processing and low temperature ion sulphurization;preset film coating and low temperature ion sulphurization;laser processing technology and low temperature ion sulphurization) , combined method involving a variety of composite processing technologies. Each process of composite processing technology was introduced in detail. The direction of development of composite processing technology was suggested based on the current problems of complex processing techniques in self-lubricating solid preparation.%渗硫层能有效降低零件的摩擦系数,提高零件的抗擦伤性能和耐磨性能,但是单纯的低温离子渗硫不能保证特定工况的生产要求,选用其它处理技术与低温离子渗硫相结合的复合处理方法可以制得表层软、亚表层硬的理想固体自润滑涂层。综述了离子多元复合渗法( S-N, S-C-N, S-O, S-Mo),两步法(喷丸和超音速纳米化处理与低温离子渗硫、预置薄膜涂层与低温离子渗硫、激光处理技术与低温离子渗硫),以及多种复合处理技术相结合法的特点和部分应用实例,着重介绍了每种复合处理技术的工艺。针对目前复合处理技术在固体自润滑薄膜制备中存在的问题,提出复合处理技术的发展方向。

  7. Hydrogen sulfide at high pressure: Change in stoichiometry

    Science.gov (United States)

    Goncharov, Alexander F.; Lobanov, Sergey S.; Kruglov, Ivan; Zhao, Xiao-Miao; Chen, Xiao-Jia; Oganov, Artem R.; Konôpková, Zuzana; Prakapenka, Vitali B.

    2016-05-01

    Hydrogen sulfide (H2S ) was studied by x-ray synchrotron diffraction and Raman spectroscopy up to 150 GPa at 180-295 K and by quantum-mechanical variable-composition evolutionary simulations. The experiments show that H2S becomes unstable with respect to formation of compounds with different structure and composition, including Cccm and a body-centered cubic like (R 3 m or I m -3 m ) H3S , the latter one predicted previously to show a record-high superconducting transition temperature, a Tc of 203 K. These experiments provide experimental ground for understanding of this record-high Tc. The experimental results are supported by theoretical structure searches that suggest the stability of H3S , H4S3 , H5S8 , H3S5 , and H S2 compounds that have not been reported previously at elevated pressures.

  8. Tribological Performance of Green Lubricant Enhanced by Sulfidation IF-MoS2

    Directory of Open Access Journals (Sweden)

    Shih-Chen Shi

    2016-10-01

    Full Text Available Biopolymers reinforced with nanoparticle (NP additives are widely used in tribological applications. In this study, the effect of NP additives on the tribological properties of a green lubricant hydroxypropyl methylcellulose (HPMC composite was investigated. The IF-MoS2 NPs were prepared using the newly developed gas phase sulfidation method to form a multilayered, polyhedral structure. The number of layers and crystallinity of IF-MoS2 increased with sulfidation time and temperature. The dispersity of NPs in the HPMC was investigated using Raman and EDS mapping and showed great uniformity. The use of NPs with HPMC enhanced the tribological performance of the composites as expected. The analysis of the worn surface shows that the friction behavior of the HPMC composite with added NPs is very sensitive to the NP structure. The wear mechanisms vary with NP structure and depend on their lubricating behaviors.

  9. Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors.

    Science.gov (United States)

    Villa-Gomez, D K; Cassidy, J; Keesman, K J; Sampaio, R; Lens, P N L

    2014-03-01

    Step changes in the organic loading rate (OLR) through variations in the influent chemical oxygen demand (CODin) concentration or in the hydraulic retention time (HRT) at constant COD/SO4(2-) ratio (0.67) were applied to create sulfide responses for the design of a sulfide control in sulfate reducing bioreactors. The sulfide was measured using a sulfide ion selective electrode (pS) and the values obtained were used to calculate proportional-integral-derivative (PID) controller parameters. The experiments were performed in an inverse fluidized bed bioreactor with automated operation using the LabVIEW software version 2009(®). A rapid response and high sulfide increment was obtained through a stepwise increase in the CODin concentration, while a stepwise decrease to the HRT exhibited a slower response with smaller sulfide increment. Irrespective of the way the OLR was decreased, the pS response showed a time-varying behavior due to sulfide accumulation (HRT change) or utilization of substrate sources that were not accounted for (CODin change). The pS electrode response, however, showed to be informative for applications in sulfate reducing bioreactors. Nevertheless, the recorded pS values need to be corrected for pH variations and high sulfide concentrations (>200 mg/L). Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors

    NARCIS (Netherlands)

    Villa Gomez, D.K.; Cassidy, J.; Keesman, K.J.; Sampaio, R.M.; Lens, P.N.L.

    2014-01-01

    Step changes in the organic loading rate (OLR) through variations in the influent chemical oxygen demand (CODin) concentration or in the hydraulic retention time (HRT) at constant COD/SO4 2- ratio (0.67) were applied to create sulfide responses for the design of a sulfide control in sulfate reducing

  11. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    Science.gov (United States)

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  12. Hydrogen sulfide induces oxidative damage to RNA and DNA in a sulfide-tolerant marine invertebrate.

    Science.gov (United States)

    Joyner-Matos, Joanna; Predmore, Benjamin L; Stein, Jenny R; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes exposed in vitro to sulfide (0-3 mmol L(-1) for 1 h) showed dose-dependent increases in oxidative stress (as 2',7'-dichlorofluorescein fluorescence) and superoxide production (as dihydroethidine fluorescence). Coelomocytes exposed in vitro to sulfide (up to 0.73 mmol L(-1) for 2 h) also acquired increased oxidative damage to RNA (detected as 8-oxo-7,8-dihydroguanosine) and DNA (detected as 8-oxo-7,8-dihydro-2'-deoxyguanosine). Worms exposed in vivo to sulfide (0-10 mmol L(-1) for 24 h) acquired elevated oxidative damage to RNA and DNA in both coelomocytes and body wall tissue. While the consequences of RNA and DNA oxidative damage are poorly understood, oxidatively damaged deoxyguanosine bases preferentially bind thymine, causing G-T transversions and potentially causing heritable point mutations. This suggests that sulfide can be an environmental mutagen in sulfide-tolerant invertebrates.

  13. Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors

    NARCIS (Netherlands)

    Villa Gomez, D.K.; Cassidy, J.; Keesman, K.J.; Sampaio, R.M.; Lens, P.N.L.

    2014-01-01

    Step changes in the organic loading rate (OLR) through variations in the influent chemical oxygen demand (CODin) concentration or in the hydraulic retention time (HRT) at constant COD/SO4 2- ratio (0.67) were applied to create sulfide responses for the design of a sulfide control in sulfate reducing

  14. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  15. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  16. sulfide – reality or fantasy?

    Directory of Open Access Journals (Sweden)

    Paulina Brodek

    2016-08-01

    Full Text Available Hydrogen sulfide (H2S is a signaling gasotransmitter, involved in different physiological and pathological processes. H2S regulates apoptosis, the cell cycle and oxidative stress. H2S exerts powerful effects on smooth muscle cells, endothelial cells, inflammatory cells, endoplasmic reticulum, mitochondria and nuclear transcription factors. H2S is known to be produced from L-cysteine, D-cysteine and L-homocysteine in the body. Four enzymes – cystathionine-b synthase (CBS, mercaptopyruvate sulfurtransferase (3-MST, cystathionine-γ lyase (CSE and cysteine aminotransferase (CAT – are involved in H2S synthesis. The biosynthetic pathway for the production of H2S from D-cysteine involves 3-MST and D-amino acid oxidase (DAO. The therapeutic potential of H2S is not clear. However, recently results have demonstrated that H2S has protective action for ischemic heart disease or hypertension, and protects against ischemia of the brain. This review summarizes the negative and the positive roles of H2S in various biological systems, for example the cardiovascular system and nervous system. We also discuss the function of classical, therapeutic and natural (for example garlic donors of H2S in pre-clinical and clinical studies.

  17. Thermal decomposition of mercuric sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Leckey, J.H.; Nulf, L.E.

    1994-10-28

    The rate of thermal decomposition of mercuric sulfide (HgS) has been measured at temperatures from 265 to 345 C. These data have been analyzed using a first-order chemical reaction model for the time dependence of the reaction and the Arrhenius equation for the temperature dependence of the rate constant. Using this information, the activation energy for the reaction was found to be 55 kcal/mol. Significant reaction vessel surface effects obscured the functional form of the time dependence of the initial portion of the reaction. The data and the resulting time-temperature reaction-rate model were used to predict the decomposition rate of HgS as a function of time and temperature in thermal treatment systems. Data from large-scale thermal treatment studies already completed were interpreted in terms of the results of this study. While the data from the large-scale thermal treatment studies were consistent with the data from this report, mass transport effects may have contributed to the residual amount of mercury which remained in the soil after most of the large-scale runs.

  18. Data collection and assessment of commonly consumed foods and recipes in six geo-political zones in Nigeria: important for the development of a National Food Composition Database and Dietary Assessment.

    Science.gov (United States)

    Ene-Obong, Henrietta N; Sanusi, Rasaki A; Udenta, Elizabeth A; Williams, Ima O; Anigo, Kola M; Chibuzo, Elizabeth C; Aliyu, Hassan M; Ekpe, Onot O; Davidson, Gloria I

    2013-10-01

    A cross-sectional study was undertaken to collect and assess commonly consumed foods/recipes from the six geopolitical zones in Nigeria for the production of food composition database (FCDB) for dietary assessment. Communities used were selected using a multi-stage sampling plan. Focus group discussions, interviews, recipe documentation, food preparations and literature reviews were employed. Qualitative methods were used to analyse and present data. SWOT (strengths, weaknesses, opportunities, and threats) analysis was used to evaluate the project. A total of 322 recipes were collected out of which 110 were soups. Food consumption patterns across the geographical zones were found to be changing. Variations in recipes and methods of preparation of similar foods were observed. Factors to be considered in the development of a country-specific FCDB were identified. There were challenges with the use of values reported in literature for Nigerian foods. The study justifies the need for a country-specific FCDB that will include traditional recipes.

  19. A study of the trace sulfide mineral assemblages in the Stillwater Complex, Montana, USA

    Science.gov (United States)

    Aird, Hannah M.; Ferguson, Katherine M.; Lehrer, Malia L.; Boudreau, Alan E.

    2017-03-01

    The sulfide assemblages of the Stillwater Complex away from the well-studied ore zones are composed mainly of variable proportions of pyrrhotite, chalcopyrite, pentlandite, and ±pyrite. Excluding vein assemblages and those affected by greenschist and lower temperature alteration, the majority can be classified into two broad assemblages, defined here as pristine (multiphase, often globular in shape) or volatile-bearing (multiphase, high-temperature, volatile-rich minerals such as biotite, hornblende, or an unmixed calcite-dolomite assemblage). The volatile-bearing assemblages are mainly found within and below the J-M reef, where native copper and sphalerite are also locally present. Pristine sulfides are found throughout the stratigraphy. Both groups can be affected by apparent S loss in the form of pyrite being converted to magnetite and chalcopyrite to a Cu-Fe-oxide (delafossite), with little to no silicate alteration. An upward trend from pentlandite-rich to pyrrhotite-rich to pyrite-rich assemblages is observed in the footwall rocks in upper GN-I, and the same trend repeats from just below the reef and continues into the overlying N-II and GN-II. Modeling suggests that the sulfide Ni in the Peridotite Zone is largely controlled by silicate Ni. When taken together, observations are most readily explained by the remobilization of selected elements by a high-temperature fluid with the apparent loss of S > Cu > Ni. This could concentrate ore metals by vapor refining, eventually producing a platinum group element-enriched sulfide ore zone, such as the J-M reef.

  20. A study of the trace sulfide mineral assemblages in the Stillwater Complex, Montana, USA

    Science.gov (United States)

    Aird, Hannah M.; Ferguson, Katherine M.; Lehrer, Malia L.; Boudreau, Alan E.

    2016-07-01

    The sulfide assemblages of the Stillwater Complex away from the well-studied ore zones are composed mainly of variable proportions of pyrrhotite, chalcopyrite, pentlandite, and ±pyrite. Excluding vein assemblages and those affected by greenschist and lower temperature alteration, the majority can be classified into two broad assemblages, defined here as pristine (multiphase, often globular in shape) or volatile-bearing (multiphase, high-temperature, volatile-rich minerals such as biotite, hornblende, or an unmixed calcite-dolomite assemblage). The volatile-bearing assemblages are mainly found within and below the J-M reef, where native copper and sphalerite are also locally present. Pristine sulfides are found throughout the stratigraphy. Both groups can be affected by apparent S loss in the form of pyrite being converted to magnetite and chalcopyrite to a Cu-Fe-oxide (delafossite), with little to no silicate alteration. An upward trend from pentlandite-rich to pyrrhotite-rich to pyrite-rich assemblages is observed in the footwall rocks in upper GN-I, and the same trend repeats from just below the reef and continues into the overlying N-II and GN-II. Modeling suggests that the sulfide Ni in the Peridotite Zone is largely controlled by silicate Ni. When taken together, observations are most readily explained by the remobilization of selected elements by a high-temperature fluid with the apparent loss of S > Cu > Ni. This could concentrate ore metals by vapor refining, eventually producing a platinum group element-enriched sulfide ore zone, such as the J-M reef.

  1. Indium sulfide buffer/CIGSSe interface engineering: Improved cell performance by the addition of zinc sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Allsop, N.A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)]. E-mail: allsop@hmi.de; Camus, C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Haensel, A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Gledhill, S.E. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lauermann, I. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lux-Steiner, M.C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Fischer, Ch.-H. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)

    2007-05-31

    Indium sulfide buffer layers deposited by the spray-ion layer gas reaction (Spray-ILGAR) technique are a viable alternative to the traditional cadmium sulfide buffer layer in thin film solar cells. In the present work we report on the results of manipulating the absorber/buffer interface between the chalcopyrite Cu(In,Ga)(S,Se){sub 2} absorber (CIGSSe) and the indium sulfide buffer. It is shown that the deposition of a small amount of zinc sulfide at the absorber/buffer interface can be used to increase the open circuit voltage. A small but significant increase of 20 mV (up to 580 mV), as compared to the pure indium sulfide buffered cells is possible leading to an increase in the overall efficiency.

  2. Controlling sulfidic tailings oxidation with surface application of crude glycerol : column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Behrooz, M.; Borden, R.C. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Civil, Construction and Environmental Engineering

    2010-07-01

    In this study, crude glycerol was used to control acid mine drainage (AMD) production in sulfidic tailings samples obtained from the Ore Knob tailings pile in Ash County, North Carolina (NC). AMD is produced when mining activities expose sulfidic materials to a moist, oxidative environment. The tailings release high sulfate heavy metal-laden effluents into the New River basin. Four experimental columns were installed in the field for a 15-month period. The glycerol was applied to the surface of unweathered sulfidic tailings. The columns were left exposed to the atmosphere at the surface and buried within the existing tailings pile to simulate naturally occurring variations in temperature and rainfall. Platinum redox electrodes and porous cup lysimeters were installed to monitor redox and geochemical conditions within the unsaturated tailings. Water samples were collected throughout the experimental period and monitored for dissolved oxygen (DO), hydrogen sulfide (H{sub 2}S), and pH. Major cations and metals were analyzed using inductively coupled plasma spectroscopy. Results of the pilot tests demonstrated that the glycerol additions resulted in large and statistically significant decreases in Fe, sulfate (SO{sub 4}), and hot acidity. Changes in sodium (Na) and potassium (K) were limited. The glycerol additions reduced the rate of AMD production and treated the AMD after it was formed through H{sub 2}S production. Results of the study will be used to create a geochemical model for characterizing AMD production in the vadose zone of the tailing pile. 10 refs., 1 tab., 2 figs.

  3. Microbial Sulfide Filter along a Benthic Redox Gradient in the Eastern Gotland Basin, Baltic Sea

    Science.gov (United States)

    Yücel, Mustafa; Sommer, Stefan; Dale, Andrew W.; Pfannkuche, Olaf

    2017-01-01

    The sediment-water interface is an important site for material exchange in marine systems and harbor unique microbial habitats. The flux of nutrients, metals, and greenhouse gases at this interface may be severely dampened by the activity of microorganisms and abiotic redox processes, leading to the “benthic filter” concept. In this study, we investigate the spatial variability, mechanisms and quantitative importance of a microbially-dominated benthic filter for dissolved sulfide in the Eastern Gotland Basin (Baltic Sea) that is located along a dynamic redox gradient between 65 and 173 m water depth. In August-September 2013, high resolution (0.25 mm minimum) vertical microprofiles of redox-sensitive species were measured in surface sediments with solid-state gold-amalgam voltammetric microelectrodes. The highest sulfide consumption (2.73–3.38 mmol m−2 day−1) occurred within the top 5 mm in sediments beneath a pelagic hypoxic transition zone (HTZ, 80–120 m water depth) covered by conspicuous white bacterial mats of genus Beggiatoa. A distinct voltammetric signal for polysulfides, a transient sulfur oxidation intermediate, was consistently observed within the mats. In sediments under anoxic waters (>140 m depth), signals for Fe(II) and aqueous FeS appeared below a subsurface maximum in dissolved sulfide, indicating a Fe(II) flux originating from older sediments presumably deposited during the freshwater Ancylus Lake that preceded the modern Baltic Sea. Our results point to a dynamic benthic sulfur cycling in Gotland Basin where benthic sulfide accumulation is moderated by microbial sulfide oxidation at the sediment surface and FeS precipitation in deeper sediment layers. Upscaling our fluxes to the Baltic Proper; we find that up to 70% of the sulfide flux (2281 kton yr−1) toward the sediment-seawater interface in the entire basin can be consumed at the microbial mats under the HTZ (80–120 m water depth) while only about 30% the sulfide flux effuses

  4. A study of the stability of cadmium sulfide/copper sulfide and cadmium sulfide copper-indium-diselenide solar cells

    Science.gov (United States)

    Noel, G.; Richard, N.; Gaines, G.

    1984-08-01

    Groups of high efficiency cadmium sulfide/copper sulfide solar cells were exposed to combinations of stresses designed to isolate and accelerate intrinsic degradation mechanisms. Stresses included elevated temperature, illumination intensity, and cell loading conditions. All stress exposures and tests were conducted in a benign (high purity argon) atmosphere. Two primary intrinsic modes of degradation were identified: degradation of the open circuit voltage under continuous illumination and nonzero loading was found to be self recovering upon interruption of illumination or upon shorting or reverse biasing the cells. It was attributed to traps in the depletion region. Recovery from decay of light generated current was not spontaneous but could be partially accomplished by annealing in a reducing (hydrogen) environment. It was attributed to changes in the stoichiometry of the copper sulfide under the influence of electric fields and currents.

  5. Lithologic controls on mineralization at the Lagunas Norte high-sulfidation epithermal gold deposit, northern Peru

    Science.gov (United States)

    Cerpa, Luis M.; Bissig, Thomas; Kyser, Kurt; McEwan, Craig; Macassi, Arturo; Rios, Hugo W.

    2013-06-01

    The 13.1-Moz high-sulfidation epithermal gold deposit of Lagunas Norte, Alto Chicama District, northern Peru, is hosted in weakly metamorphosed quartzites of the Upper Jurassic to Lower Cretaceous Chimú Formation and in overlying Miocene volcanic rocks of dacitic to rhyolitic composition. The Dafne and Josefa diatremes crosscut the quartzites and are interpreted to be sources of the pyroclastic volcanic rocks. Hydrothermal activity was centered on the diatremes and four hydrothermal stages have been defined, three of which introduced Au ± Ag mineralization. The first hydrothermal stage is restricted to the quartzites of the Chimú Formation and is characterized by silice parda, a tan-colored aggregate of quartz-auriferous pyrite-rutile ± digenite infilling fractures and faults, partially replacing silty beds and forming cement of small hydraulic breccia bodies. The δ34S values for pyrite (1.7-2.2 ‰) and digenite (2.1 ‰) indicate a magmatic source for the sulfur. The second hydrothermal stage resulted in the emplacement of diatremes and the related volcanic rocks. The Dafne diatreme features a relatively impermeable core dominated by milled slate from the Chicama Formation, whereas the Josefa diatreme only contains Chimú Formation quartzite clasts. The third hydrothermal stage introduced the bulk of the mineralization and affected the volcanic rocks, the diatremes, and the Chimú Formation. In the volcanic rocks, classic high-sulfidation epithermal alteration zonation exhibiting vuggy quartz surrounded by a quartz-alunite and a quartz-alunite-kaolinite zone is observed. Company data suggest that gold is present in solid solution or micro inclusions in pyrite. In the quartzite, the alteration is subtle and is manifested by the presence of pyrophyllite or kaolinite in the silty beds, the former resulting from relatively high silica activities in the fluid. In the quartzite, gold mineralization is hosted in a fracture network filled with coarse alunite

  6. Sulfide capacities of fayalite-base slags

    Science.gov (United States)

    Simeonov, S. R.; Sridhar, R.; Toguri, J. M.

    1995-04-01

    The sulfide capacities of fayalite-base slags were measured by a gas-slag equilibration technique under controlled oxygen and sulfur potentials similar to those encountered in the pyrometallurgical processing of nonferrous metals. The oxygen pressure range was from 10-9.5 to 10-11 MPa and the sulfur pressure range from 10-3 to 10-4.5 MPa, over a temperature range of 1473 to 1623 K. The slags studied were FeO-SiO2 at silica saturation and those with addition of CaO, MgO, and Al2O3 to determine their effect on sulfide capacities. For these slags, the sulfide capacities were found to vary from 10-3.3 to 10-5. The sulfide capacities increased with increasing temperature from 1473 to 1623 K. A comparison of the reported plant data on sulfur content of industrial slags shows good agreement with the present experimental results. The present data will be useful in estimating metal losses in slag due to metal sulfide entrainment in nonferrous smelters.

  7. Hydrogen sulfide: neurochemistry and neurobiology.

    Science.gov (United States)

    Qu, K; Lee, S W; Bian, J S; Low, C-M; Wong, P T-H

    2008-01-01

    Current evidence suggests that hydrogen sulfide (H2S) plays an important role in brain functions, probably acting as a neuromodulator as well as an intracellular messenger. In the mammalian CNS, H2S is formed from the amino acid cysteine by the action of cystathionine beta-synthase (CBS) with serine (Ser) as the by-product. As CBS is a calcium and calmodulin dependent enzyme, the biosynthesis of H2S should be acutely controlled by the intracellular concentration of calcium. In addition, it is also regulated by S-adenosylmethionine which acts as an allosteric activator of CBS. H2S, as a sulfhydryl compound, has similar reducing properties as glutathione. In neurons, H2S stimulates the production of cAMP probably by direct activation of adenylyl cyclase and thus activate cAMP-dependent processes. In astrocytes, H2S increases intracellular calcium to an extent capable of inducing and propagating a "calcium wave", which is a form of calcium signaling among these cells. Possible physiological functions of H2S include potentiating long-term potentials through activation of the NMDA receptors, regulating the redox status, maintaining the excitatory/inhibitory balance in neurotransmission, and inhibiting oxidative damage through scavenging free radicals and reactive species. H2S is also involved in CNS pathologies such as stroke and Alzheimer's disease. In stroke, H2S appears to act as a mediator of ischemic injuries and thus inhibition of its production has been suggested to be a potential treatment approach in stroke therapy.

  8. Band offset in zinc oxy-sulfide/cubic-tin sulfide interface from X-ray photoelectron spectroscopy

    Science.gov (United States)

    K. C., Sanal; Nair, P. K.; Nair, M. T. S.

    2017-02-01

    Zinc oxy-sulfide, ZnOxS1-x, has been found to provide better band alignment in thin film solar cells of tin sulfide of orthorhombic crystalline structure. Here we examine ZnOxS1-x/SnS-CUB interface, in which the ZnOxS1-x thin film was deposited by radio frequency (rf) magnetron sputtering on SnS thin film of cubic (CUB) crystalline structure with a band gap (Eg) of 1.72 eV, obtained via chemical deposition. X-ray photoelectron spectroscopy provides the valence band maxima of the materials and hence places the conduction band offset of 0.41 eV for SnS-CUB/ZnO0.27S0.73 and -0.28 eV for SnS-CUB/ZnO0.88S0.12 interfaces. Thin films of ZnOxS1-x with 175-240 nm in thickness were deposited from targets prepared with different ZnO to ZnS molar ratios. With the target of molar ratio of 1:13.4, the thin films are of composition ZnO0.27S0.73 with hexagonal crystalline structure and with that of 1:1.7 ratio, it is ZnO0.88S0.12. The optical band gap of the ZnOxS1-x thin films varies from 2.90 eV to 3.21 eV as the sulfur to zinc ratio in the film increases from 0.12:1 to 0.73:1 as determined from X-ray diffraction patterns. Thus, band offsets sought for absorber materials and zinc oxy-sulfide in solar cells may be achieved through a choice of ZnO:ZnS ratio in the sputtering target.

  9. Microbial oceanography of anoxic oxygen minimum zones

    DEFF Research Database (Denmark)

    Ulloa, Osvaldo; Canfield, Donald E; DeLong, Edward F

    2012-01-01

    Vast expanses of oxygen-deficient and nitrite-rich water define the major oxygen minimum zones (OMZs) of the global ocean. They support diverse microbial communities that influence the nitrogen economy of the oceans, contributing to major losses of fixed nitrogen as dinitrogen (N(2)) and nitrous...... environmental genomics and geochemical studies show the presence of other relevant processes, particularly those associated with the sulfur and carbon cycles. AMZs correspond to an intermediate state between two "end points" represented by fully oxic systems and fully sulfidic systems. Modern and ancient AMZs...... and sulfidic basins are chemically and functionally related. Global change is affecting the magnitude of biogeochemical fluxes and ocean chemical inventories, leading to shifts in AMZ chemistry and biology that are likely to continue well into the future....

  10. Influence of Metal Sulfides as Anode Catalysts on Performance of H2S SOFC

    Institute of Scientific and Technical Information of China (English)

    钟理; 刘曼; 韩国林; CHUANGKar

    2003-01-01

    Two anode catalysts with Pt, MoS2 and composite metal sulfides (MoS2+NiS), are investigated for electrochemical oxidation of hydrogen sulfide in solid oxide fuel cell (SOFC) at temperatures 750-850℃. The catalysts comprising MoS2 and MoS2+NiS exhibited good electrical conductivity and catalytic activity. MoS2 and composite catalysts were found to be more active than Pt, a widely used catalyst for high temperature H2S/O2 fuel cell at 750-850℃. However, MoS2 itself sublimes above 450℃. In contrast, composite catalysts containing both Mo and transition metal (Ni) are shown to be stable and effective in promoting the oxidation of H2S in SOFC up to 850℃. However, electric contact is poor between the platinum current collecting layer and the composite metal sulfide layer, so that the cell performance becomes worse. This problem is overcome by adding conductive Ag powder into the anode layer (forming MoS2+NiS+Ag anode material) to increase anode electrical conductance instead of applying a thin laver of platinum on the top of anode.

  11. Solar thermal extraction of copper from sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Guesdon, C.; Sturzenegger, M.

    2003-03-01

    With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates re-search on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite (Cu{sub 2}S) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS{sub 2}) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO{sub 2}, and is beneficial to the removal of volatile impurities. Chemical equilibrium calculations for CuFeS{sub 2} contaminated with enargite (Cu{sub 3}AsS{sub 4}) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation. (author)

  12. The Anarraaq Zn-Pb-Ag and barite deposit, northern Alaska: Evidence for replacement of carbonate by barite and sulfides

    Science.gov (United States)

    Kelley, K.D.; Dumoulin, J.A.; Jennings, S.

    2004-01-01

    The Anarraaq deposit in northern Alaska consists of a barite body, estimated to be as much as 1 billion metric tons, and a Zn-Pb-Ag massive sulfide zone with an estimated resource of about 18 Mt at 18 percent Zn, 5.4 percent Pb, and 85 g/t Ag. The barite and sulfide minerals are hosted by the uppermost part of the Mississippian Kuna Formation (Ikalukrok unit) that consists of carbonaceous and siliceous mudstone or shale interbedded with carbonate. The amount of interbedded carbonate in the Anarraaq deposit is atypical of the district as a whole, comprising as much as one third of the section. The total thickness of the Ikalukrok unit is considerably greater in the area of the deposit (210 to almost 350 m) than to the north and south (maximum of 164 m). The mineralized zone at Anarraaq is lens shaped and has a relatively flat top and a convex base. It also ranges greatly in thickness, from a few meters to more than 100 m. Textures of some of the carbonate layers are distinctive, consisting of nodules within siliceous mudstone or layers interbedded with shale. Many of the layers contain calcitized sponge spicules or radiolarians in a carbonate matrix. Textures of barite and sulfide minerals mimic those of carbonate and provide unequivocal evidence that replacement of precursor carbonate was an important process. Barite and sulfide textures include either nodular, bladed grains of various sizes that resemble spicules (observed only with iron sulfides) or well-rounded forms that are replaced radiolarians. Mineralization at Anarraaq probably occurred in a fault-bounded Carboniferous basin during early diagenesis in the shallow subsurface. The shape and size of the mineralized body suggest that barite and sulfides replaced calcareous mass flow deposits in a submarine channel. The distribution of biogenic and/or early diagenetic silica may have served as impermeable barriers to the fluids, thereby focusing and controlling fluid flow through unreplaced carbonate layers

  13. Membrane for hydrogen recovery from streams containing hydrogen sulfide

    Science.gov (United States)

    Agarwal, Pradeep K.

    2007-01-16

    A membrane for hydrogen recovery from streams containing hydrogen sulfide is provided. The membrane comprises a substrate, a hydrogen permeable first membrane layer deposited on the substrate, and a second membrane layer deposited on the first layer. The second layer contains sulfides of transition metals and positioned on the on a feed side of the hydrogen sulfide stream. The present invention also includes a method for the direct decomposition of hydrogen sulfide to hydrogen and sulfur.

  14. Acute inhalation toxicity of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Benson, J.M.; Hahn, F.F.; Barr, E.B. [and others

    1995-12-01

    Carbonyl sulfide (COS), a colorless gas, is a side product of industrial procedures sure as coal hydrogenation and gasification. It is structurally related to and is a metabolite of carbon disulfide. COS is metabolized in the body by carbonic anhydrase to hydrogen sulfide (H{sub 2}S), which is thought to be responsible for COS toxicity. No threshold limit value for COS has been established. Results of these studies indicate COS (with an LC{sub 50} of 590 ppm) is slightly less acutely toxic than H{sub 2}S (LC{sub 50} of 440 ppm).

  15. Use of biogenic sulfide for ZnS precipitation

    NARCIS (Netherlands)

    Esposito, G.; Veeken, A.; Weijma, J.; Lens, P.N.L.

    2006-01-01

    A 600 ml continuously stirred tank reactor was used to assess the performance of a zinc sulfide precipitation process using a biogenic sulfide solution (the effluent of a sulfate-reducing bioreactor) as sulfide source. In all experiments, a proportional-integral (PI) control algorithm was used to co

  16. A physiologically based kinetic model for bacterial sulfide oxidation

    NARCIS (Netherlands)

    Klok, J.B.; Graaff, M. de; Bosch, P.L. van den; Boelee, N.C.; Keesman, K.J.; Janssen, A.J.W.M.

    2013-01-01

    In the biotechnological process for hydrogen sulfide removal from gas streams, a variety of oxidation products can be formed. Under natron-alkaline conditions, sulfide is oxidized by haloalkaliphilic sulfide oxidizing bacteria via flavocytochrome c oxidoreductase. From previous studies, it was concl

  17. Finding Massive Sulfides at Mid-Ocean Ridges

    Science.gov (United States)

    Barckhausen, Udo; Dressel, Ingo; Ehrhardt, Axel; Heyde, Ingo; Schwarz-Schampera, Ulrich; Schreckenberger, Bernd; Schwalenberg, Katrin

    2017-04-01

    hydrothermal activity. In cases where these magnetic anomalies coincide with structural features like major or crossing fault zones, a detailed investigation with deep towed instruments follows. A combination of particle and redox-anomaly observation in the water column a few hundred meters above the seafloor and an ultra high resolution (1m) deep tow bathymetric survey has proven capable of detecting active and inactive hydrothermal vent sites with their associated Massive Sulfides deposits. Once these deposits have been detected and confirmed by video camera observation and geologic sampling, further geophysical surveying at the seafloor with specialized electromagnetic tools provides the opportunity to map the horizontal extension of the deposits, even where buried under sediments or talus, and ultimately to give estimates on the volume of the ore body. Further geophysical surveys including reflection and refraction seismic studies can be helpful to understand the large scale tectonic setting of the hydrothermal systems.

  18. Sulfide remediation by pulsed injection of nitrate into a low temperature Canadian heavy oil reservoir.

    Science.gov (United States)

    Voordouw, Gerrit; Grigoryan, Aleksandr A; Lambo, Adewale; Lin, Shiping; Park, Hyung Soo; Jack, Thomas R; Coombe, Dennis; Clay, Bill; Zhang, Frank; Ertmoed, Ryan; Miner, Kirk; Arensdorf, Joseph J

    2009-12-15

    Sulfide formation by oil field sulfate-reducing bacteria (SRB) can be diminished by the injection of nitrate, stimulating the growth of nitrate-reducing bacteria (NRB). We monitored the field-wide injection of nitrate into a low temperature (approximately 30 degrees C) oil reservoir in western Canada by determining aqueous concentrations of sulfide, sulfate, nitrate, and nitrite, as well as the activities of NRB in water samples from 3 water plants, 2 injection wells, and 15 production wells over 2 years. The injection water had a low sulfate concentration (approximately 1 mM). Nitrate (2.4 mM, 150 ppm) was added at the water plants. Its subsequent distribution to the injection wells gave losses of 5-15% in the pipeline system, indicating that most was injected. Continuous nitrate injection lowered the total aqueous sulfide output of the production wells by 70% in the first five weeks, followed by recovery. Batchwise treatment of a limited section of the reservoir with high nitrate eliminated sulfide from one production well with nitrate breakthrough. Subsequent, field-wide treatment with week-long pulses of 14 mM nitrate gave breakthrough at an additional production well. However, this trend was reversed when injection with a constant dose of 2.4 mM (150 ppm) was resumed. The results are explained by assuming growth of SRB near the injection wellbore due to sulfate limitation. Injection of a constant nitrate dose inhibits these SRB initially. However, because of the constant, low temperature of the reservoir, SRB eventually grow back in a zone further removed from the injection wellbore. The resulting zonation (NRB closest to and SRB further away from the injection wellbore) can be broken by batch-wise increases in the concentration of injected nitrate, allowing it to re-enter the SRB-dominated zone.

  19. Magmatic Conduit Metallogenic System in Jinchuan Cu-Ni (PGE) Sulfide Deposit

    Science.gov (United States)

    Su, S.; Tang, Z.; Zhou, M.; Song, C.

    2014-12-01

    The Jinchuan Cu-Ni (PGE) sulfide deposit is located in the southwestern margin of North China Craton. Jinchuan ultramafic intrusion hosts the third largest magmatic Cu-Ni deposit in the world. There are mainly four orebodies, namely, orebody-58, orebody-24, orebody-1, and orebody-2, respectively from west to east in the deposit. The primary characteristics of Jinchuan Cu-Ni sulfide deposit are the following: (1) There is an obvious boundary between orebodys and country rocks, usually orebodys intruded into country rocks. (2) "sulfide melts" migrate and settle in the later stage of magma evolution. (3) Fluid Minerals Assemblages are found in the sulfide ores, there is Phl+Cc+Pn+Ccp+Po in orebody-2; Phl+Dol+AP+Pn+Ccp+Po in orebody-24; Q+Mag+AP+Pn+Ccp+Po in orebody-58. (4) Massive sulfides mainly occur in orebody-2, and its PGE content is very rare. Pt-Pd enrichment zones mainly occur in orebody-1; orebody-24 and orebody-58. Ir vs. Ru, Rh, Pt, Pd show positive relationship in orebody-2, but Ir vs. Ru, Rh show positive relationship, Ir vs. Pt, Pd exhibit negative relationship in orebody-1, orebody-24 and orebody-58. The modeling of Ir-Pd shows that the massive sulfide in orebody-2 maybe the origin of MSS. Pt-Pd enrichment zones in orebody-1 orebody-24 and orebody-58 are the relic liquid of monosulfide solid solution segregation; (5) Cu/Ni value is 1.24 in orebody-58, 1.56 in orebody-24, 1.83 in orebody-1, and 2.06 in orebody-2. These features imply that (1) "ore magma" or "melt-fluid bearing metal" formed in the staging chamber in depth; (2) "ore magma" might contain a lot of fluids; (3) "melt-fluid bearing metal" flow moves as a whole; (4) The moving direction of melt-fluid bearing metal flow is form west to east. The ores are enriched in Ni in the front, and enriched in Cu, Pt, Pd in the back of Jinchuan Magmatic Conduit Metallogenic System.

  20. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices.

    NARCIS (Netherlands)

    Tangerman, A.

    2009-01-01

    This review deals with the measurement of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  1. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices

    NARCIS (Netherlands)

    Tangerman, Albert

    2009-01-01

    This review deals with the measurement of the volatile Sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  2. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices

    NARCIS (Netherlands)

    Tangerman, Albert

    2009-01-01

    This review deals with the measurement of the volatile Sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol

  3. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices.

    NARCIS (Netherlands)

    Tangerman, A.

    2009-01-01

    This review deals with the measurement of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol

  4. Sulfur and oxygen isotope geochemistry of acid mine drainage--the polymetallic sulfide deposit "himmelfahrt fundgrube" in Freiberg (Germany).

    Science.gov (United States)

    Haubrich, F; Tichomirowa, M

    2002-06-01

    We investigated physical, chemical and isotope (S, O) parameters of sulfate from acid mine drainage from the polymetallic sulfide ore deposit Freiberg (Gennany), which was mined for more than eight hundred years. Two main groups of water were distinguished: 1. Flowing mine water with sulfate concentrations of less than 9,000 mg/l and pH values higher than 3.2, 2. Pore water in weathered low grade ores and pools with sulfate concentrations higher than 9000mg/l and pH values below 3.2. The sulfur and oxygen isotope composition of sulfate from flowing mine waters reflects mixing of sulfate from two sulfur sources: a) atmospheric sulfur from precipitation and b) sulfate formed as a result of sulfide oxidation processes. Sulfur isotope values of mine water sulfate were used to estimate the contribution of sulfate derived through oxidation of sulfides. The sulfur isotope composition of pore water sulfate and precipitated sulfate (jarosite) from weathered low grade ore samples is identical to the sulfur isotope composition of primary sulfides. The oxygen isotope composition of pore water sulfate from low grade ore samples indicates that the oxidation process proceeds relatively slowly in 02-depleted waters, probably without significant microbial catalysis.

  5. The Influence of Hydrogen on the Properties of Zinc Sulfide Thin Films Deposited by Magnetron Sputtering

    OpenAIRE

    2014-01-01

    Zinc sulfide thin films have been deposited with hydrogen in Ar and Ar+H2 atmosphere by radio frequency magnetron sputtering. The thickness, structural properties, composition, surface morphology, and optical and electrical properties of the films have been investigated. Effect of hydrogen on the properties of the film was studied. The results showed that hydrogen leads to better crystallinity and larger crystallite size of ZnS polycrystalline films. The band gaps of the films in Ar+H2 are ab...

  6. In Situ Synthesis of Metal Sulfide Nanoparticles Based on 2D Metal-Organic Framework Nanosheets.

    Science.gov (United States)

    Lu, Qipeng; Zhao, Meiting; Chen, Junze; Chen, Bo; Tan, Chaoliang; Zhang, Xiao; Huang, Ying; Yang, Jian; Cao, Feifei; Yu, Yifu; Ping, Jianfeng; Zhang, Zhicheng; Wu, Xue-Jun; Zhang, Hua

    2016-09-01

    A facile in situ synthetic method is developed to synthesize metal sulfide nanoparticles based on 2D M-TCPP (M = Cu, Cd, or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin)) metal-organic framework nanosheets. The obtained CuS/Cu-TCPP composite nanosheet is used as the active material in photoelectrochemical cells, showing notably increased photocurrent due to the improved exciton separation and charge carrier transport.

  7. Changes in Dimethyl Sulfide Oceanic Distribution due to Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Cameron-Smith, P; Elliott, S; Maltrud, M; Erickson, D; Wingenter, O

    2011-02-16

    Dimethyl sulfide (DMS) is one of the major precursors for aerosols and cloud condensation nuclei in the marine boundary layer over much of the remote ocean. Here they report on coupled climate simulations with a state-of-the-art global ocean biogeochemical model for DMS distribution and fluxes using present-day and future atmospheric CO{sub 2} concentrations. They find changes in zonal averaged DMS flux to the atmosphere of over 150% in the Southern Ocean. This is due to concurrent sea ice changes and ocean ecosystem composition shifts caused by changes in temperature, mixing, nutrient, and light regimes. The largest changes occur in a region already sensitive to climate change, so any resultant local CLAW/Gaia feedback of DMS on clouds, and thus radiative forcing, will be particularly important. A comparison of these results to prior studies shows that increasing model complexity is associted with reduced DMS emissions at the equator and increased emissions at high latitudes.

  8. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco

    DEFF Research Database (Denmark)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild

    2015-01-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree...... such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers...... (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit...

  9. Trace elements in tourmalines from massive sulfide deposits and tourmalinites: Geochemical controls and exploration applications

    Science.gov (United States)

    Griffin, W.L.; Slack, J.F.; Ramsden, A.R.; Win, T.T.; Ryan, C.G.

    1996-01-01

    Trace element contents of tourmalines from massive sulfide deposits and tourmalinites have been determined in situ by proton microprobe; >390 analyses were acquired from 32 polished thin sections. Concentrations of trace elements in the tourmalines vary widely, from zones are relatively homogeneous, suggesting that these trace elements are contained within the crystal structure of the tourmaline, and are not present in inclusions. The highest base metal contents are in ore-related tourmaline samples from Kidd Creek (Ontario), Broken Hill (Australia), and Sazare (Japan). Tourmaline data from these and many other massive sulfide deposits cluster by sample and display broadly linear trends on Zn vs. Fe plots, suggesting chemical control by temperature and hydrothermal and/or metamorphic fluid-mineral equilibria. Significant Ni occurs only in samples from the Kidd Creek Cu-Zn-Pb-Ag deposit, which is associated with a large footwall ultramafic body. An overall antithetic relationship between Zn and Ni probably reflects fluid source controls. Mn is correlated with Fe in tourmalines from barren associations, and possibly in some tourmalines associated with sulfide vein deposits. Sn increases systematically with Fe content irrespective of association; the highest values are found in schorls from granites. Other trace elements are generally uncorrelated with major element concentrations (e.g., Sr-Ca). Base metal proportions in the tourmalines show systematic patterns on ternary Cu-Pb-Zn diagrams that correlate well with the major commodity metals in the associated massive sulfide deposits. For example, data for tourmalines from Cu-Zn deposits (e.g., Ming mine, Newfoundland) fall mainly on the Cu-Zn join, whereas those from Pb-Zn deposits (e.g., Broken Hill, Australia) plot on the Pb-Zn join; no data fall on the Cu-Pb join, consistent with the lack of this metal association in massive sulfide deposits. The systematic relationship between base metal proportions in the

  10. A batch assay to measure microbial hydrogen sulfide production from sulfur-containing solid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Mei, E-mail: msun8@uncc.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States); Sun, Wenjie, E-mail: wsun@smu.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States); Department of Civil and Environmental Engineering, Southern Methodist University, PO Box 750340, Dallas, TX (United States); Barlaz, Morton A., E-mail: barlaz@ncsu.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States)

    2016-05-01

    Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H{sub 2}S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often necessitates the installation of expensive removal systems. For landfill operators to understand the cost of managing sulfur-containing wastes, an estimate of the H{sub 2}S production potential is needed. The objective of this study was to develop and demonstrate a biochemical sulfide potential (BSP) test to measure the amount of H{sub 2}S produced by different types of sulfur-containing wastes in a relatively fast (30 days) and inexpensive (125 mL serum bottles) batch assay. This study confirmed the toxic effect of H{sub 2}S on both sulfate reduction and methane production in batch systems, and demonstrated that removing accumulated H{sub 2}S by base adsorption was effective for mitigating inhibition. H{sub 2}S production potentials of coal combustion fly ash, flue gas desulfurization residual, municipal solid waste combustion ash, and construction and demolition waste were determined in BSP assays. After 30 days of incubation, most of the sulfate in the wastes was converted to gaseous or aqueous phase sulfide, with BSPs ranging from 0.8 to 58.8 mL H{sub 2}S/g waste, depending on the chemical composition of the samples. Selected samples contained solid phase sulfide which contributed to the measured H{sub 2}S yield. A 60 day incubation in selected samples resulted in 39–86% additional sulfide production. H{sub 2}S production measured in BSP assays was compared with that measured in simulated landfill reactors and that calculated from chemical analyses. H{sub 2}S production in BSP assays and in reactors was lower than the stoichiometric values calculated from chemical composition for all wastes tested, demonstrating

  11. A batch assay to measure microbial hydrogen sulfide production from sulfur-containing solid wastes.

    Science.gov (United States)

    Sun, Mei; Sun, Wenjie; Barlaz, Morton A

    2016-05-01

    Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H2S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often necessitates the installation of expensive removal systems. For landfill operators to understand the cost of managing sulfur-containing wastes, an estimate of the H2S production potential is needed. The objective of this study was to develop and demonstrate a biochemical sulfide potential (BSP) test to measure the amount of H2S produced by different types of sulfur-containing wastes in a relatively fast (30days) and inexpensive (125mL serum bottles) batch assay. This study confirmed the toxic effect of H2S on both sulfate reduction and methane production in batch systems, and demonstrated that removing accumulated H2S by base adsorption was effective for mitigating inhibition. H2S production potentials of coal combustion fly ash, flue gas desulfurization residual, municipal solid waste combustion ash, and construction and demolition waste were determined in BSP assays. After 30days of incubation, most of the sulfate in the wastes was converted to gaseous or aqueous phase sulfide, with BSPs ranging from 0.8 to 58.8mLH2S/g waste, depending on the chemical composition of the samples. Selected samples contained solid phase sulfide which contributed to the measured H2S yield. A 60day incubation in selected samples resulted in 39-86% additional sulfide production. H2S production measured in BSP assays was compared with that measured in simulated landfill reactors and that calculated from chemical analyses. H2S production in BSP assays and in reactors was lower than the stoichiometric values calculated from chemical composition for all wastes tested, demonstrating the importance of assays to estimate the microbial sulfide production

  12. Self-assembly of biomorphic carbon/sulfur microstructures in sulfidic environments

    Science.gov (United States)

    Cosmidis, Julie; Templeton, Alexis S.

    2016-09-01

    In natural and laboratory-based environments experiencing sustained counter fluxes of sulfide and oxidants, elemental sulfur (S0)--a key intermediate in the sulfur cycle--can commonly accumulate. S0 is frequently invoked as a biomineralization product generated by enzymatic oxidation of hydrogen sulfide and polysulfides. Here we show the formation of S0 encapsulated in nanometre to micrometre-scale tubular and spherical organic structures that self-assemble in sulfide gradient environments in the absence of any direct biological activity. The morphology and composition of these carbon/sulfur microstructures so closely resemble microbial cellular and extracellular structures that new caution must be applied to the interpretation of putative microbial biosignatures in the fossil record. These reactions between sulfide and organic matter have important implications for our understanding of S0 mineralization processes and sulfur interactions with organic carbon in the environment. They furthermore provide a new pathway for the synthesis of carbon-sulfur nanocomposites for energy storage technologies.

  13. Optimum injection dose rate of hydrogen sulfide scavenger for treatment of petroleum crude oil

    Directory of Open Access Journals (Sweden)

    T.M. Elshiekh

    2016-03-01

    Full Text Available Hydrogen sulfide H2S scavengers are chemicals that favorably react with hydrogen sulfide gas to eliminate it and produce environmental friendly products. These products depend on the type and composition of the scavenger and the conditions at which the reaction takes place. The scavenger should be widely available and economical for industry acceptance by having a low unit cost. The optimum values of H2S scavenger injection dose rate of scavenging hydrogen sulfide from the multiphase fluid produced at different wells conditions in one of the Petroleum Companies in Egypt were studied. The optimum values of H2S scavenger injection dose rate depend on pipe diameter, pipe length, gas molar mass velocity, inlet H2S concentration and pressure. The optimization results are obtained for different values of these parameters using the software program Lingo. In general, the optimum values of H2S scavenger injection dose rate of the scavenging of hydrogen sulfide are increased by increasing of the pipe diameter and increasing the inlet H2S concentration, and decreased by increasing the pipe length, gas molar mass velocity and pressure.

  14. Platinum metals in magmatic sulfide ores

    Science.gov (United States)

    Naldrett, A.J.; Duke, J.M.

    1980-01-01

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. Copyright ?? 1980 AAAS.

  15. Hydrogen Sulfide in Preeclampsia : Potential Therapeutic Implications

    NARCIS (Netherlands)

    Holwerda, Kim

    2015-01-01

    The thesis provide insights into the production and possible therapeutic effect of the gaseous molecule hydrogen sulfide (H2S) in preeclampsia (PE). H2S is an important molecule in the (human) body. It is among others involved in blood pressure regulation, stimulation of vascular growth and

  16. Nucleation of mercury sulfide by dealkylation

    Science.gov (United States)

    Enescu, Mironel; Nagy, Kathryn L.; Manceau, Alain

    2016-12-01

    Metal sulfide minerals are assumed to form naturally at ambient conditions via reaction of a metallic element with (poly)sulfide ions, usually produced by microbes in oxygen-depleted environments. Recently, the formation of mercury sulfide (β-HgS) directly from linear Hg(II)-thiolate complexes (Hg(SR)2) in natural organic matter and in cysteine solutions was demonstrated under aerated conditions. Here, a detailed description of this non-sulfidic reaction is provided by computations at a high level of molecular-orbital theory. The HgS stoichiometry is obtained through the cleavage of the S-C bond in one thiolate, transfer of the resulting alkyl group (R’) to another thiolate, and subsequent elimination of a sulfur atom from the second thiolate as a thioether (RSR’). Repetition of this mechanism leads to the formation of RS-(HgS)n-R chains which may self-assemble in parallel arrays to form cinnabar (α-HgS), or more commonly, quickly condense to four-coordinate metacinnabar (β-HgS). The mechanistic pathway is thermodynamically favorable and its predicted kinetics agrees with experiment. The results provide robust theoretical support for the abiotic natural formation of nanoparticulate HgS under oxic conditions and in the absence of a catalyst, and suggest a new route for the (bio)synthesis of HgS nanoparticles with improved technological properties.

  17. Microaeration reduces hydrogen sulfide in biogas

    Science.gov (United States)

    Although there are a variety of biological and chemical treatments for removal of hydrogen sulfide (H2S) from biogas, all require some level of chemical or water inputs and maintenance. In practice, managing biogas H2S remains a significant challenge for agricultural digesters where labor and opera...

  18. Microbial Fuel Cells for Sulfide Removal

    NARCIS (Netherlands)

    Rabaey, K.; Sompel, van de S.; Maignien, L.; Boon, N.; Aelterman, P.; Clauwaert, P.; Schamphelaire, de L.; The Pham, H.; Vermeulen, J.; Verhaege, M.; Lens, P.N.L.; Verstraete, W.

    2006-01-01

    Thus far, microbial fuel cells (MFCs) have been used to convert carbon-based substrates to electricity. However, sulfur compounds are ubiquitously present in organic waste and wastewater. In this study, a MFC with a hexacyanoferrate cathodic electrolyte was used to convert dissolved sulfide to eleme

  19. Acid volatile sulfide (AVS)- a comment

    NARCIS (Netherlands)

    Meysman, F.J.R.; Middelburg, J.J.

    2005-01-01

    The review by Rickard and Morse (this volume) adequately summarizes our current understanding with respect to acid-volatile sulfides (AVS). At the same time, this review addresses some of the misunderstandings with regard to measurements and dynamics of this important sedimentary sulfur pool. In

  20. Comparison of Hydrogen Sulfide Analysis Techniques

    Science.gov (United States)

    Bethea, Robert M.

    1973-01-01

    A summary and critique of common methods of hydrogen sulfide analysis is presented. Procedures described are: reflectance from silver plates and lead acetate-coated tiles, lead acetate and mercuric chloride paper tapes, sodium nitroprusside and methylene blue wet chemical methods, infrared spectrophotometry, and gas chromatography. (BL)

  1. Hydrogen Sulfide in Preeclampsia : Potential Therapeutic Implications

    NARCIS (Netherlands)

    Holwerda, Kim

    2015-01-01

    The thesis provide insights into the production and possible therapeutic effect of the gaseous molecule hydrogen sulfide (H2S) in preeclampsia (PE). H2S is an important molecule in the (human) body. It is among others involved in blood pressure regulation, stimulation of vascular growth and modulati

  2. Sulfide Precipitation in Wastewater at Short Timescales

    DEFF Research Database (Denmark)

    Kiilerich, Bruno; van de Ven, Wilbert; Nielsen, Asbjørn Haaning

    2017-01-01

    that this is not the case for sulfide precipitation by ferric iron. Instead, the reaction time was found to be on a timescale where it must be considered when performing end-of-pipe treatment. For real wastewaters at pH 7, a stoichiometric ratio around 14 mol Fe(II) (mol S(−II))−1 was obtained after 1.5 s, while the ratio......Abatement of sulfides in sewer systems using iron salts is a widely used strategy. When dosing at the end of a pumping main, the reaction kinetics of sulfide precipitation becomes important. Traditionally the reaction has been assumed to be rapid or even instantaneous. This work shows...... dropped to about 5 mol Fe(II) (mol S(−II))−1 after 30 s. Equilibrium calculations yielded a theoretic ratio of 2 mol Fe(II) (mol S(−II))−1, indicating that the process had not equilibrated within the span of the experiment. Correspondingly, the highest sulfide conversion only reached 60%. These findings...

  3. Oxidation and Precipitation of Sulfide in Sewer Networks

    DEFF Research Database (Denmark)

    Nielsen, A. H.

    were studied in both wastewater and biofilms. Particular emphasis was on the importance of iron in the sulfur cycle. Iron is typically among the dominant metals in wastewater. The experiments showed that, ferric iron (Fe(III)) that was added to anaerobic wastewater was rapidly reduced to ferrous iron...... (Fe(II)) and precipitated subsequently with dissolved sulfide as ferrous sulfide (FeS). The ferrous sulfide precipitation was relatively fast, but not immediate. Despite the very low solubility of ferrous sulfide, initially present iron did not react completely with sulfide. This observation...

  4. Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.

    Science.gov (United States)

    Zhang, Haiming; Yu, Xinzhi; Guo, Di; Qu, Baihua; Zhang, Ming; Li, Qiuhong; Wang, Taihong

    2013-08-14

    Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-μm structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors.

  5. Evolution of chemical and isotopic composition of inorganic carbon in a complex semi-arid zone environment: Consequences for groundwater dating using radiocarbon

    Science.gov (United States)

    Meredith, K. T.; Han, L. F.; Hollins, S. E.; Cendón, D. I.; Jacobsen, G. E.; Baker, A.

    2016-09-01

    Estimating groundwater age is important for any groundwater resource assessment and radiocarbon (14C) dating of dissolved inorganic carbon (DIC) can provide this information. In semi-arid zone (i.e. water-limited environments), there are a multitude of reasons why 14C dating of groundwater and traditional correction models may not be directly transferable. Some include; (1) the complex hydrological responses of these systems that lead to a mixture of different ages in the aquifer(s), (2) the varied sources, origins and ages of organic matter in the unsaturated zone and (3) high evaporation rates. These all influence the evolution of DIC and are not easily accounted for in traditional correction models. In this study, we determined carbon isotope data for; DIC in water, carbonate minerals in the sediments, sediment organic matter, soil gas CO2 from the unsaturated zone, and vegetation samples. The samples were collected after an extended drought, and again after a flood event, to capture the evolution of DIC after varying hydrological regimes. A graphical method (Han et al., 2012) was applied for interpretation of the carbon geochemical and isotopic data. Simple forward mass-balance modelling was carried out on key geochemical processes involving carbon and agreed well with observed data. High values of DIC and δ13CDIC, and low 14CDIC could not be explained by a simple carbonate mineral-CO2 gas dissolution process. Instead it is suggested that during extended drought, water-sediment interaction leads to ion exchange processes within the top ∼10-20 m of the aquifer which promotes greater calcite dissolution in saline groundwater. This process was found to contribute more than half of the DIC, which is from a mostly 'dead' carbon source. DIC is also influenced by carbon exchange between DIC in water and carbonate minerals found in the top 2 m of the unsaturated zone. This process occurs because of repeated dissolution/precipitation of carbonate that is dependent on

  6. Sulfide removal by moderate oxygenation of anaerobic sludge environments

    Energy Technology Data Exchange (ETDEWEB)

    Van der Zee, F.P.; Villaverde, S.; Polanco, F. [Valladolid Univ., Valladolid (Spain). Dept. of Chemical Engineering; Garcia, P.A.

    2004-07-01

    Treating wastewater through anaerobic bioreactors results in the formation of hydrogen sulfide. The sulfide can be removed from the biogas by introducing air directly into the anaerobic bioreactor system. This study presents the results of batch experiments that provided a better insight into the fate of sulfur compounds and oxygen during microaerobic sulfide oxidation in granular sludge. It was shown that sulfide could be removed rapidly upon introduction of low amounts of oxygen to the sulfide-amended batch vials with granular sludge treating vinasse. Initially, the sulfide was oxidized to elemental sulfur, thiosulfate and polysulfide. Significant production of sulfate did not occur. The introduction of oxygen, however, could result in the growth of aerobic organic-chemical oxygen demand-oxidizing bacteria that compete with sulfide oxidation for oxygen. 6 refs., 1 tab., 1 fig.

  7. Species Composition and Diversity of Planktonic Copepods in Culture Zone of Eucheuma%麒麟菜养殖区海域浮游桡足类种类组成与多样性

    Institute of Scientific and Technical Information of China (English)

    张钰; 王仁恩; 黄勃; 杨文杰

    2012-01-01

    [目的]研究麒麟菜养殖区海域浮游桡足类种类组成与多样性.[方法]于2011年1~12月对麒麟菜养殖区海尾镇海域进行生态环境调查,分析麒麟菜养殖海区浮游桡足类种类组成与多样性,并对其与季节及麒麟菜养殖的关系进行了初步探讨.[结果]此次调查期间共出现了浮游桡足类56种,其中有13种是全年出现的,以夏、秋季较多,春、冬较少;四季共出现优势桡足类9种,出现的生态类型有近岸低盐型、广温广盐型、高温广盐型,其中以近岸低盐类型占主导.麒麟菜丰富区域浮游桡足类种类多样性高于麒麟菜不丰富区域.[结论]麒麟菜养殖和季节变化对浮游桡足类多样性有一定的影响.%[Objective] The research aimed to study the species composition and diversity of planktonic copepods in culture zone of Eucheuma. [Method] The ecological environment of sea area in Haiwei Town of culture zone of Eucheuma was surveyed during 2011.1 -2011. The species composition and diversity of planktonic copepod in culture zone of Eucheuma were analyzed and its relationship with the culture of Eucheuma was preliminarily discussed. [Result] 56 species of Copepod were identified in this survey. Among them, 13 species occurred yearly. More species of Copepod were found in summer and autumn, while less species were found in spring and winter. 9 dominant species found in 4 seasons were neritic and hypohaline type, eurythermal and euryhaline type , hyperthermal and euryhaline type. The dominant ecological type was neritic and hypohaline type . The diversity of the planktonic eopepods in richer region in the culture zone of Eucheuma was higher. [Conclusion] The diversity of Copepods were affected by Eucheuma culture and seasonal variation.

  8. Optimizing Culture Medium Composition to Improve Oligodendrocyte Progenitor Cell Yields In Vitro from Subventricular Zone-Derived Neural Progenitor Cell Neurospheres

    Science.gov (United States)

    Franco, Paula G.; Pasquini, Juana M.; Silvestroff, Lucas

    2015-01-01

    Neural Stem and Progenitor Cells (NSC/NPC) are gathering tangible recognition for their uses in cell therapy and cell replacement therapies for human disease, as well as a model system to continue research on overall neural developmental processes in vitro. The Subventricular Zone is one of the largest NSC/NPC niches in the developing mammalian Central Nervous System, and persists through to adulthood. Oligodendrocyte progenitor cell (OPC) enriched cultures are usefull tools for in vitro studies as well as for cell replacement therapies for treating demyelination diseases. We used Subventricular Zone-derived NSC/NPC primary cultures from newborn mice and compared the effects of different growth factor combinations on cell proliferation and OPC yield. The Platelet Derived Growth Factor-AA and BB homodimers had a positive and significant impact on OPC generation. Furthermore, heparin addition to the culture media contributed to further increase overall culture yields. The OPC generated by this protocol were able to mature into Myelin Basic Protein-expressing cells and to interact with neurons in an in vitro co-culture system. As a whole, we describe an optimized in vitro method for increasing OPC. PMID:25837625

  9. Optimizing culture medium composition to improve oligodendrocyte progenitor cell yields in vitro from subventricular zone-derived neural progenitor cell neurospheres.

    Science.gov (United States)

    Franco, Paula G; Pasquini, Juana M; Silvestroff, Lucas

    2015-01-01

    Neural Stem and Progenitor Cells (NSC/NPC) are gathering tangible recognition for their uses in cell therapy and cell replacement therapies for human disease, as well as a model system to continue research on overall neural developmental processes in vitro. The Subventricular Zone is one of the largest NSC/NPC niches in the developing mammalian Central Nervous System, and persists through to adulthood. Oligodendrocyte progenitor cell (OPC) enriched cultures are usefull tools for in vitro studies as well as for cell replacement therapies for treating demyelination diseases. We used Subventricular Zone-derived NSC/NPC primary cultures from newborn mice and compared the effects of different growth factor combinations on cell proliferation and OPC yield. The Platelet Derived Growth Factor-AA and BB homodimers had a positive and significant impact on OPC generation. Furthermore, heparin addition to the culture media contributed to further increase overall culture yields. The OPC generated by this protocol were able to mature into Myelin Basic Protein-expressing cells and to interact with neurons in an in vitro co-culture system. As a whole, we describe an optimized in vitro method for increasing OPC.

  10. Gold in the Brunswick No. 12 volcanogenic massive sulfide deposit, Bathurst Mining Camp, Canada: Evidence from bulk ore analysis and laser ablation ICP-MS data on sulfide phases

    Science.gov (United States)

    McClenaghan, Sean H.; Lentz, David R.; Martin, Jillian; Diegor, Wilfredo G.

    2009-07-01

    The 329-Mt Brunswick No. 12 volcanogenic massive sulfide deposit (total resource of 163 Mt at 10.4% Zn, 4.2% Pb, 0.34% Cu, and 115 g/t Ag) is hosted within a Middle Ordovician bimodal volcanic and sedimentary sequence. Massive sulfides are for the most part syngenetic, and the bulk of the sulfide ore occurs as a Zn-Pb-rich banded sulfide facies that forms an intimate relationship with a laterally extensive Algoma-type iron formation and defines the Brunswick Horizon. Zone refining of stratiform sulfides is considered to have resulted in the development of a large replacement-style Cu-rich basal sulfide facies, which is generally confined between the banded sulfide facies and an underlying stringer sulfide zone. Complex polyphase deformation and associated lower- to upper-greenschist facies regional metamorphism is responsible for the present geometry of the deposit. Textural modification has resulted in a general increase in grain size through the development of pyrite and arsenopyrite porphyroblasts, which tend to overprint primary mineral assemblages. Despite the heterogeneous ductile deformation, primary features have locally been preserved, such as fine-grained colloform pyrite and base and precious metal zonation within the Main Zone. Base metal and trace element abundances in massive sulfides from the Brunswick No. 12 deposit indicate two distinct geochemical associations. The basal sulfide facies, characterized by a proximal high-temperature hydrothermal signature (Cu-Co-Bi-Se), contains generally low Au contents averaging 0.39 ppm ( n = 34). Conversely, Au is enriched in the banded sulfide facies, averaging 1.1 ppm Au ( n = 21), and is associated with an exhalative suite of elements (Zn-Pb-As-Sb-Ag-Sn). Finely laminated sulfide lenses hosted by iron formation at the north end of the Main Zone are further enriched in Au, averaging 1.7 ppm ( n = 41) and ranging up to 8.2 ppm. Laser ablation inductively coupled plasma-mass spectrometry (ICP-MS) analyses of

  11. Immiscibility of Fluid Phases at Magmatic-hydrothermal Transition: Formation of Various PGE-sulfide Mineralization for Layered Basic Intrusions

    Science.gov (United States)

    Zhitova, L.; Borisenko, A.; Morgunov, K.; Zhukova, I.

    2007-12-01

    Fluid inclusions in quartz of the Merensky Reef (Bushveld Complex, South Africa) and the Chineisky Pluton (Transbaikal Region, Russia) were studied using cryometry, microthermometry, Raman-spectroscopy, LA ICP- MS, scanning electronic microscopy, gas-chromatography and isotopic methods. This allowed us to document some examples of fluid phase separation resulting in formation of different types of PGE-sulfide mineralization for layered basic intrusions. The results obtained show at least three generations of fluid separated from boiling residual alumosilicate intercumulus liquid of the Merensky Reef. The earliest fluid phase composed of homogenous high-dense methane and nitrogen gas mixture was identified in primary gas and co-existing anomalous fluid inclusions from symplectitic quartz. The next generation, heterophase fluid, composed of brines containing a free low-dense (mostly of carbon dioxide) gas phase, was observed in primary multiphase and coexisting gas-rich inclusions of miarolitic quartz crystals. The latest generation was also a heterophase fluid (low salinity water-salt solution and free low-dense methane gas phase) found in primary water-salt and syngenetic gas inclusions from peripheral zones of miarolitic quartz crystals. For the Chineisky Pluton reduced endocontact magmatogene fluids changed to oxidized low salinity hydrothermal fluids in exocontact zone. This resulted in formation of sulfide-PGE enrichment marginal zones of intrusion. The results obtained give us a possibility to suggest that: 1) Fluid phase separation is a typical feature of magmatogene fluids for layered basic intrusions. 2) Reduced fluids can extract and transport substantial PGE and sulfide concentrations. 3) Oxidation of reduced fluids is one of the most important geochemical barriers causing abundant PGE minerals and sulfides precipitation. This in turn results in both formation of PGE reefs or enriched contact zones of layered basic intrusions. This work was supported by

  12. Study of crystallization behavior of poly(phenylene sulfide

    Directory of Open Access Journals (Sweden)

    Liliana B. Nohara

    2006-06-01

    Full Text Available Poly(phenylene sulfide (PPS is an engineering thermoplastic polymer that presents high temperature resistance (glass transition temperature around 85 ºC and melting point at 285 ºC. These properties combined with its mechanical properties and its high chemical resistance allows its use in technological applications such as molding resins and as matrix for structural thermoplastic composites. During the manufacture of thermoplastic composites, the polymer is exposed to repeated melting, quenching and crystallization processes. The properties of semicrystalline polymers, such as PPS, depend on its crystallization behavior. This work deals with the PPS crystallization kinetics under different thermal cycles. This study was performed under isothermal conditions in a differential scanning calorimetry (DSC, coupled to Perkin Elmer crystallization software referred to as Pyris Kinetics - Crystallization. The results were correlated with microscopic analyses carried out in a polarized light microscope, equipped with a controlled heating and cooling accessory. In this case, the experimental conditions were the same adopted for the DSC analyses. From the results, parameters could be established to be used in the composite manufacture.

  13. P-O-rich sulfide phase in CM chondrites: Constraints on its origin on the CM parent body

    Science.gov (United States)

    Zhang, Ai-Cheng; Itoh, Shoichi; Yurimoto, Hisayoshi; Hsu, Wei-Biao; Wang, Ru-Cheng; Taylor, Lawrence A.

    2016-01-01

    CM chondrites are a group of primitive meteorites that have recorded the alteration history of the early solar system. We report the occurrence, chemistry, and oxygen isotopic compositions of P-O-rich sulfide phase in two CM chondrites (Grove Mountains [GRV] 021536 and Murchison). This P-O-rich sulfide is a polycrystalline aggregate of nanometer-size grains. It occurs as isolated particles or aggregates in both CM chondrites. These grains, in the matrix and in type-I chondrules from Murchison, were partially altered into tochilinite; however, grains enclosed by Ca-carbonate are much less altered. This P-O-rich sulfide in Murchison is closely associated with magnetite, FeNi phosphide, brezinaite (Cr3S4), and eskolaite (Cr2O3). In addition to sulfur as the major component, this sulfide contains ~6.3 wt% O, ~5.4 wt% P, and minor amounts of hydrogen. Analyses of oxygen isotopes by SIMS resulted in an average δ18O value of -22.5 ‰ and an average Δ17O value of 0.2 ± 9.2 ‰ (2σ). Limited variations in both chemical compositions and electron-diffraction patterns imply that the P-O-rich sulfide may be a single phase rather than a polyphase mixture. Several features indicate that this P-O-rich sulfide phase formed at low temperature on the parent body, most likely through the alteration of FeNi metal (a) close association with other low-temperature alteration products, (b) the presence of hydrogen, (c) high Δ17O values and the presence in altered mesostasis of type-I chondrules and absence in type-II chondrules. The textural relations of the P-O-rich sulfide and other low-temperature minerals reveal at least three episodic-alteration events on the parent body of CM chondrites (1) formation of P-O-rich sulfide during sulfur-rich aqueous alteration of P-rich FeNi metal, (2) formation of Ca-carbonate during local carbonation, and (3) alteration of P-O-rich sulfide and formation of tochilinite during a period of late-stage intensive aqueous alteration.

  14. Screening of genes related to sulfide metabolism in Urechis unicinctus (Echiura, Urechidae) using suppression subtractive hybridization and cDNA microarray analysis.

    Science.gov (United States)

    Shi, Xiaoli; Shao, Mingyu; Zhang, Litao; Ma, Yubin; Zhang, Zhifeng

    2012-09-01

    Exogenous sulfide can generally induce metabolic injuries in most organisms and even cause death. However, organisms inhabiting intertidal zones, hydrothermal vents, and cold seeps, can tolerate, metabolize, and utilize sulfide. In this study, both suppression subtractive hybridization and cDNA microarray analysis were employed to screen sulfide metabolism-related genes from the body wall in echiuran worm Urechis unicinctus, a marine sediment species. A total of 3456 monoclones were isolated and 82 were identified as differentially expressed genes in worms exposed to 50 μM sulfide for 24 h, compared to controls. The identified genes encoded proteins with multiple processes, including metabolism, cellular process, biological regulation, response to stimulus, multicellular organismal process, localization, development, and cellular component organization. Eight genes, serase, vacuolar protein, src tyrosine kinase, sulfide oxidase-like oxidoreductase, aprataxin, SN-RNP, aminopeptidase, and predicted protein, were selected to verify expression in the worm using qRT-PCR. The agreement of gene expression evaluation was 62.5% between the results of microarray analysis and qRT-PCR. These new data will provide clues for further probing of the molecular mechanism of sulfide metabolism.

  15. Poly(methyl methacrylate)/layered zinc sulfide nanocomposites: Preparation, characterization and the improvements in thermal stability, flame retardant and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Biao; Zhou, Keqing; Jiang, Saihua [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Shi, Yongqian [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road, Suzhou, Jiangsu 215123 (China); Wang, Bibo [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Gui, Zhou, E-mail: zgui@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road, Suzhou, Jiangsu 215123 (China)

    2014-08-15

    Highlights: • Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method. • We prepare PMMA/LZnS nanocomposites by in situ bulk polymerization of MMA. • PMMA/LZnS nanocomposites were investigated by TGA, DSC, MCC, UV–vis and PL test. • The thermal stability, flame retardant and optical properties of PMMA are improved. - Abstract: Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method and poly(methyl methacrylate) (PMMA)/layered zinc sulfide nanocomposites were obtained by in situ bulk polymerization of methyl methacrylate (MMA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-synthesized layered zinc sulfide and PMMA/layered zinc sulfide nanocomposites. Microscale combustion calorimeter (MCC), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were used to test the thermal properties of the composites. Ultraviolet visible (UV–vis) transmittance spectra and photoluminence (PL) spectra were obtained to investigate the optical properties of the composites. From the results, the thermal degradation temperature is increased by 20–50 °C, the peak of heat release rate (pHRR) and total heat release (THR) are both decreased by above 30%, and the photoluminence intensity is enhanced with the increasing loading of layered zinc sulfide.

  16. Formation of Zn- and Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: implications for sulfide bioavailability to chemoautotrophs

    Directory of Open Access Journals (Sweden)

    Yucel Mustafa

    2008-05-01

    Full Text Available Abstract Background The speciation of dissolved sulfide in the water immediately surrounding deep-ocean hydrothermal vents is critical to chemoautotrophic organisms that are the primary producers of these ecosystems. The objective of this research was to identify the role of Zn and Fe for controlling the speciation of sulfide in the hydrothermal vent fields at the Eastern Lau Spreading Center (ELSC in the southern Pacific Ocean. Compared to other well-studied hydrothermal systems in the Pacific, the ELSC is notable for unique ridge characteristics and gradients over short distances along the north-south ridge axis. Results In June 2005, diffuse-flow ( 250°C vent fluids were collected from four field sites along the ELSC ridge axis. Total and filtered Zn and Fe concentrations were quantified in the vent fluid samples using voltammetric and spectrometric analyses. The results indicated north-to-south variability in vent fluid composition. In the high temperature vent fluids, the ratio of total Fe to total Zn varied from 39 at Kilo Moana, the most northern site, to less than 7 at the other three sites. The concentrations of total Zn, Fe, and acid-volatile sulfide indicated that oversaturation and precipitation of sphalerite (ZnS(s and pyrite (FeS2(s were possible during cooling of the vent fluids as they mixed with the surrounding seawater. In contrast, most samples were undersaturated with respect to mackinawite (FeS(s. The reactivity of Zn(II in the filtered samples was tested by adding Cu(II to the samples to induce metal-exchange reactions. In a portion of the samples, the concentration of labile Zn2+ increased after the addition of Cu(II, indicating the presence of strongly-bound Zn(II species such as ZnS clusters and nanoparticles. Conclusion Results of this study suggest that Zn is important to sulfide speciation at ELSC vent habitats, particularly at the southern sites where Zn concentrations increase relative to Fe. As the hydrothermal

  17. Elevated corrosion rates and hydrogen sulfide in homes with 'Chinese Drywall'

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Joseph G.; MacIntosh, David L. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Harvard School of Public Health, 677 Huntington Avenue, Boston, MA (United States); Saltzman, Lori E. [U.S. Consumer Product Safety Commission, Bethesda, MD (United States); Baker, Brian J. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Matheson, Joanna M.; Recht, Joel R. [U.S. Consumer Product Safety Commission, Bethesda, MD (United States); Minegishi, Taeko; Fragala, Matt A.; Myatt, Theodore A. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Spengler, John D.; Stewart, James H. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Harvard School of Public Health, 677 Huntington Avenue, Boston, MA (United States); McCarthy, John F., E-mail: jmcccarthy@eheinc.com [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States)

    2012-06-01

    In December 2008, the U.S. Consumer Product Safety Commission (CPSC) began receiving reports about odors, corrosion, and health concerns related to drywall originating from China. In response, a detailed environmental health and engineering evaluation was conducted of 41 complaint and 10 non-complaint homes in the Southeast U.S. Each home investigation included characterization of: 1) drywall composition; 2) indoor and outdoor air quality; 3) temperature, moisture, and building ventilation; and 4) copper and silver corrosion rates. Complaint homes had significantly higher hydrogen sulfide concentrations (mean 0.82 vs. < LOD {mu}g/m{sup 3}, p < 0.05), and significantly greater rates of copper sulfide and silver sulfide corrosion compared to non-complaint homes (Cu{sub 2}S: 476 vs. < 32 A/30 d, p < 0.01; Ag{sub 2}S: 1472 vs. 389 A/30 d, p < 0.01). The abundance of carbonate and strontium in drywall was also elevated in complaint homes, and appears to be useful objective marker of problematic drywall in homes that meet other screening criteria (e.g., constructed or renovated in 2006-2007, reports of malodor and accelerated corrosion). This research provides empirical evidence of the direct association between homes constructed with 'Chinese Drywall' in 2006-2007 and elevated corrosion rates and hydrogen sulfide concentrations in indoor air. - Highlights: Black-Right-Pointing-Pointer Environmental measurements in homes with and without 'Chinese Drywall' Black-Right-Pointing-Pointer Homes with 'Chinese Drywall' had higher hydrogen sulfide concentrations Black-Right-Pointing-Pointer Homes with 'Chinese Drywall' had elevated corrosion rates Black-Right-Pointing-Pointer Study provides empirical evidence of reported associations.

  18. Gold contents of both mantle-derived xenoliths and sulfides in them from eastern China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The gold contents of 59 samples of mantle-derived xenoliths, along with 85 samples of sulfide assem-blages in them, of Cenozoic basalt from eight districts in eastern China are analyzed. The gold contents of mantle xenoliths usually fall in the range of 10-9―10-8, whereas those of the sulfide assemblages fall in the range of 10-4―10-2. This implies that the latter are several hundred thousand times higher than the former, and thus that Au in the mantle is concentrated mostly in sulfide assemblages. Gold con-tents of both mantle-derived xenoliths and sulfide assemblages in them are inhomogeneous spatially, but their distribution rules are similar. Except the samples from Hainan Province, either the mantle xenoliths with high gold content or sulfide assemblages of the mantle-derived xenoliths with high gold content are distributed mostly on the north and south margins of the North China platform (Hannuoba of Hebei Province and Linqu, Changle of Shandong Province), corresponding to districts with concen-trated gold deposits in northwest Hebei Province and Jiaodong Peninsula of Shandong Province. This may reflect the correlativity in age, nature and composition between the continental crust and the un-derlying lithospheric mantle. The underlying lithospheric mantle of the North China platform is an an-cient gold-rich lithospheric mantle. The gold-rich lithospheric mantle may be the material source of later activation, enrichment, transportation and mineralization of gold by auriferous CO2 mantle fluids.

  19. Stratigraphic setting and mineralogy of the Arctic volcanogenic massive sulfide prospect, Ambler district, Alaska.

    Science.gov (United States)

    Schmidt, J.M.

    1986-01-01

    The Arctic prospect, south central Brooks Range, is among the 30 largest of 508 volcanic-hosted massive sulphide deposits in the world. The massive sulphide lenses are interlayered with graphitic schist between metamorphosed rhyolite porphyries in Middle Devonian to early Mississippian metamorphosed volcanic, volcaniclastic and sedimentary rocks. Hydrothermal alteration is of three types: chloritic, phyllic s.l., and pyrite-phengite, each type strata-distinctively and respectively below, in, and above the sulphides. Maximum alteration conforms with metal zoning in the sulfides to suggest predominantly northwestward dispersal from a linear vent area in the elongate basin containing the deposit.-G.J.N.

  20. Characterization of Fe-S Minerals influenced by buried ancient woods in the intertidal zone,East China Sea

    Institute of Scientific and Technical Information of China (English)

    YUAN LinXi; SUN LiGuang; FORTIN Danielle; WANG YuHong; WU ZiJun; YIN XueBin

    2009-01-01

    An ancient wood layer dated at about 5600 cal. a BP by AMS14C dating was discovered in the intertidal zone, East China Sea. Samples affected by ancient woods, including fresh coast bedrock, weathering bedrock, seepage water from coast, seepage water from ancient wood layer, intertidal seawater, fresh water, beach mud, ancient wood barks and ancient peat, were collected for geochemical analysis. The beach mud and the bacteriogenic iron oxides (BIOS) in coastal seepage water were analyzed by min-eralogical and high-resolution transmission electron microscopy (HRTEM)-selected area electron dif-fraction (SAED) analysis. Inorganic sulfur compositions and δ34S of the ancient peat and the beach mud were determined. The results showed that Fe, Mn, S (SO42-) were enriched in the intertidal area at different levels, very likely caused by fermentation of ancient woods. The presence of abundant iron-oxidizing bacteria (FeOB) and sulfate-reducing bacteria (SRB) in this intertidal zone was confirmed by HRTEM-SAED observation, and these bacteria were involved in Fe-S cycle to induce extracellular biomineralization. The negative δ34Sv-CDT (-2.9%.) likely indicated the biogenic origin of iron-sulfide minerals in the beach mud at high sulfate reduction rate (SRR). These findings are helpful for under-standing the biogeochemical Fe-S cycle and biomineralization process at high organic matter deposition rate and high SRR in the intertidal zone, estuary, or near shoreline.

  1. Sulfide, the first inorganic substrate for human cells.

    Science.gov (United States)

    Goubern, Marc; Andriamihaja, Mireille; Nübel, Tobias; Blachier, François; Bouillaud, Frédéric

    2007-06-01

    Hydrogen sulfide (H2S) is produced inside the intestine and is known as a poison that inhibits cellular respiration at the level of cytochrome oxidase. However, sulfide is used as an energetic substrate by many photo- and chemoautotrophic bacteria and by animals such as the lugworm Arenicola marina. The concentrations of sulfide present in their habitats are comparable with those present in the human colon. Using permeabilized colonic cells to which sulfide was added by an infusion pump we show that the maximal respiratory rate of colonocyte mitochondria in presence of sulfide compares with that obtained with succinate or L-alpha-glycerophosphate. This oxidation is accompanied by mitochondrial energization. In contrast, other cell types not naturally exposed to high concentration of sulfide showed much lower oxidation rates. Mitochondria showed a very high affinity for sulfide that permits its use as an energetic substrate at low micromolar concentrations, hence, below the toxic level. However, if the supply of sulfide exceeds the oxidation rate, poisoning renders mitochondria inefficient and our data suggest that an anaerobic mechanism involving partial reversion of Krebs cycle already known in invertebrates takes place. In conclusion, this work provides additional and compelling evidence that sulfide is not only a toxic compound. According to our study, sulfide appears to be the first inorganic substrate for mammalian cells characterized thus far.

  2. The Evolution of Sulfide Tolerance in the Cyanobacteria

    Science.gov (United States)

    Miller, Scott R.; Bebout, Brad M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Understanding how the function of extant microorganisms has recorded both their evolutionary histories and their past interactions with the environment is a stated goal of astrobiology. We are taking a multidisciplinary approach to investigate the diversification of sulfide tolerance mechanisms in the cyanobacteria, which vary both in their degree of exposure to sulfide and in their capacity to tolerate this inhibitor of photosynthetic electron transport. Since conditions were very reducing during the first part of Earth's history and detrital sulfides have been found in Archean sediments, mechanisms conferring sulfide tolerance may have been important for the evolutionary success of the ancestors of extant cyanobacteria. Two tolerance mechanisms have been identified in this group: (1) resistance of photosystem II, the principal target of sulfide toxicity; and (2) maintenance of the ability to fix carbon despite photosystem II inhibition by utilizing sulfide as an electron donor in photosystem I - dependent, anoxygenic photosynthesis. We are presently collecting comparative data on aspects of sulfide physiology for laboratory clones isolated from a variety of habitats. These data will be analyzed within a phylogenetic framework inferred from molecular sequence data collected for these clones to test how frequently different mechanisms of tolerance have evolved and which tolerance mechanism evolved first. In addition, by analyzing these physiological data together with environmental sulfide data collected from our research sites using microelectrodes, we can also test whether the breadth of an organism's sulfide tolerance can be predicted from the magnitude of variation in environmental sulfide concentration it has experienced in its recent evolutionary past and whether greater average sulfide concentration and/or temporal variability in sulfide favors the evolution of a particular mechanism of sulfide tolerance.

  3. Plasma-chemical treatment of hydrogen sulfide in natural gas processing. Final report, May 1991--December 1992

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, J.B.L.; Doctor, R.D. [Argonne National Lab., IL (United States)

    1993-05-01

    A new process for the treatment of hydrogen sulfide waste that uses microwave plasma-chemical technology has been under development in Russia and the United States. Whereas the present waste-treatment technology, at best, only recovers sulfur, this novel process recovers both hydrogen and sulfur by dissociating hydrogen sulfide in a plasma by means of a microwave or radio-frequency reactor. A research project has been undertaken to determine the suitability of the plasma process in natural gas processing applications. The experiments tested acid-gas compositions with 30--65% carbon dioxide, 0--7% water, and 0--0.2% of a standard mixture of pipeline gas. The balance gas in all cases was hydrogen sulfide. The reactor pressure for the experiments was 50 torr, and the microwave power was 1.0 kW. Conversions of hydrogen sulfide ranged from 80 to 100%, while 35--50% of the carbon dioxide was converted to carbon monoxide. This conversion of carbon dioxide resulted in a loss of hydrogen production and an energy loss from a hydrogen sulfide waste-treatment perspective. Tests of a direct natural gas treatment concept showed that hydrocarbon losses were unacceptably high; consequently, the concept would not be economically viable.

  4. Experimental Studies on the Sulfide Capacities of CaO-SiO2-CrOx Slags

    Science.gov (United States)

    Wang, Lijun; Seetharaman, Seshadri

    2010-04-01

    To understand the desulfurization process during the refining of Cr-containing steel grades, this work was initiated to study the reactions between Cr-sulfur and chromium-containing slags. The sulfide capacities of CaO-SiO2-CrOx pseudo-ternary slags were measured using the traditional gas-slag equilibration technique between 1823 K and 1923 K. Sixteen different slag compositions were examined, and two different equilibrium oxygen partial pressures were used to understand the impact of the varying valence of Cr on the sulfide capacities. The results showed that log10 Cs varied linearly with the reciprocal T, and the slope was higher than the corresponding value reported for the binary CaO-SiO2 of corresponding composition. It was difficult to isolate the relative effects of the bi- and trivalent Cr in the slags because the Cr2+/Cr3+ ratio was influenced by the basicity of the slag. By using the equation developed by these authors earlier that related Cr2+/Cr3+ with basicity, oxygen partial pressure, and temperature, it was possible to obtain an approximate trend of the CrO effect on the sulfide capacities; viz. the sulfide shows a decreasing trend as Cr2+ replaces Ca2+ in the slag. With a continued increase of Cr2+ content, indications of the occurrence of a minimum point were observed; beyond which the sulfide capacities showed a slight increasing trend. The latter was attributed, based on slag-structure analysis by Gaskell et al., to the increasing extent of the polymerization reaction releasing oxygen ions for sulfide reactions.

  5. Iron-sulfide redox flow batteries

    Science.gov (United States)

    Xia, Guan-Guang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2013-12-17

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  6. Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2013-01-01

    A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts satisfact......A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts...... by the competition between chain‐branching and ‐propagating steps; modeling predictions are particularly sensitive to the branching fraction for the OCS + O reaction to form CO + SO or CO2 + S....

  7. Speciation of arsenic in sulfidic waters

    Directory of Open Access Journals (Sweden)

    Ford Robert G

    2003-03-01

    Full Text Available Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH2S from 10-7.5 to 10-3.0 M, ΣAs from 10-5.6 to 10-4.8 M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH30, and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10-4.3 M at neutral pH. Conversion from neutral As(OH30 to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions.

  8. Iron-sulfide redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Guanguang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2016-06-14

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  9. Effects of humic substances on precipitation and aggregation of zinc sulfide nanoparticles

    Science.gov (United States)

    Deonarine, Amrika; Lau, Boris L.T.; Aiken, George R.; Ryan, Joseph N.; Hsu-Kim, Heileen

    2011-01-01

    Nanoparticulate metal sulfides such as ZnS can influence the transport and bioavailability of pollutant metals in anaerobic environments. The aim of this work was to investigate how the composition of dissolved natural organic matter (NOM) influences the stability of zinc sulfide nanoparticles as they nucleate and aggregate in water with dissolved NOM. We compared NOM fractions that were isolated from several surface waters and represented a range of characteristics including molecular weight, type of carbon, and ligand density. Dynamic light scattering was employed to monitor the growth and aggregation of Zn−S−NOM nanoparticles in supersaturated solutions containing dissolved aquatic humic substances. The NOM was observed to reduce particle growth rates, depending on solution variables such as type and concentration of NOM, monovalent electrolyte concentration, and pH. The rates of growth increased with increasing ionic strength, indicating that observed growth rates primarily represented aggregation of charged Zn−S−NOM particles. Furthermore, the observed rates decreased with increasing molecular weight and aromatic content of the NOM fractions, while carboxylate and reduced sulfur content had little effect. Differences between NOM were likely due to properties that increased electrosteric hindrances for aggregation. Overall, results of this study suggest that the composition and source of NOM are key factors that contribute to the stabilization and persistence of zinc sulfide nanoparticles in the aquatic environment.

  10. Studies on ternary silver sulfides; Fukugo gin ryukabutsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-31

    Some sulfides containing silver show high ion mobility based on movability of silver, whose application is expected. Studies have been carried out centrally on synthesis of new compounds of ternary silver sulfides by elucidating the relationship among their compositions, structures and properties by means of crystal chemical studies mainly on their phase relationship. A few new compounds have been synthesized, such as the ones having the argyrodite family compound structure including transition metals. The synthesizing process takes a kind of turbulent liquid state structure at elevated temperatures because of movability of silver, but silver is fixed at low temperatures in different sites between skeleton structures made by other atoms. These studies on phase transfer, structures, and silver movability have been based on X-ray diffraction, infrared and Raman spectroscopic measurements, NMR, measurements of electric and thermal characteristics. For the studies related to compositions and structures of ternary metal sulfides which take compound crystalline structure, a structure analyzing method based on multi-dimensional hyperspatial groups was used. This paper reports the summary of the studies in seven chapters, and dwells on the remaining problems and future prospects. 158 refs., 114 figs., 65 tabs.

  11. Effects of humic substance on precipitation and aggregation of zinc sulfide nanoparticles

    Science.gov (United States)

    Deonarine, Amrika; Lau, Boris L.T.; Aiken, George R.; Ryan, Joseph N.; Hsu-Kim, Heileen

    2011-01-01

    Nanoparticulate metal sulfides such as ZnS can influence the transport and bioavailability of pollutant metals in anaerobic environments. The aim of this work was to investigate how the composition of dissolved natural organic matter (NOM) influences the stability of zinc sulfide nanoparticles as they nucleate and aggregate in water with dissolved NOM. We compared NOM fractions that were isolated from several surface waters and represented a range of characteristics including molecular weight, type of carbon, and ligand density. Dynamic light scattering was employed to monitor the growth and aggregation of Zn-S-NOM nanoparticles in supersaturated solutions containing dissolved aquatic humic substances. The NOM was observed to reduce particle growth rates, depending on solution variables such as type and concentration of NOM, monovalent electrolyte concentration, and pH. The rates of growth increased with increasing ionic strength, indicating that observed growth rates primarily represented aggregation of charged Zn-S-NOM particles. Furthermore, the observed rates decreased with increasing molecular weight and aromatic content of the NOM fractions, while carboxylate and reduced sulfur content had little effect. Differences between NOM were likely due to properties that increased electrosteric hindrances for aggregation. Overall, results of this study suggest that the composition and source of NOM are key factors that contribute to the stabilization and persistence of zinc sulfide nanoparticles in the aquatic environment.

  12. Subsurface heaters with low sulfidation rates

    Energy Technology Data Exchange (ETDEWEB)

    John, Randy Carl; Vinegar, Harold J

    2013-12-10

    A system for heating a hydrocarbon containing formation includes a heater having an elongated ferromagnetic metal heater section. The heater is located in an opening in a formation. The heater section is configured to heat the hydrocarbon containing formation. The exposed ferromagnetic metal has a sulfidation rate that goes down with increasing temperature of the heater, when the heater is in a selected temperature range.

  13. Hydrogen sulfide prodrugs—a review

    Directory of Open Access Journals (Sweden)

    Yueqin Zheng

    2015-09-01

    Full Text Available Hydrogen sulfide (H2S is recognized as one of three gasotransmitters together with nitric oxide (NO and carbon monoxide (CO. As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications.

  14. Hydrogen sulfide prodrugs—a review

    Science.gov (United States)

    Zheng, Yueqin; Ji, Xingyue; Ji, Kaili; Wang, Binghe

    2015-01-01

    Hydrogen sulfide (H2S) is recognized as one of three gasotransmitters together with nitric oxide (NO) and carbon monoxide (CO). As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications. PMID:26579468

  15. Soil Development and Fertility Characteristics of Inland Valleys in the Rain Forest Zone of Nigeria:Mineralogical Composition and Particle-Size Distribution

    Institute of Scientific and Technical Information of China (English)

    S.S.ABE; G.O.OYEDIRAN; T.MASUNAGA; S.YAMAMOTO; T.HONNA; T.WAKATSUKI

    2009-01-01

    The particle-size distribution and mineralogical composition of the clay (<2 μm) and fine-sand (0.25-0.10 mm)fractions in soils of two inland valleys in Abakaliki and Bende,Southeast Nigeria,were investigated to provide basic information on soil-forming processes and agricultural potentials.These soils were silty or clayey,deriving from Cretaceous or Tertiary shale materials.The particle-size distribution and its computation on a clay-free basis revealed relatively remarkable lithologic breaks in a couple of pedons.The effect of lithologic discontinuities on soil mineralogical composition was not,however,conspicuous.Petrographic investigation revealed that quartz predominantly comprised the fine-sand fraction in the soils at both study sites.Nevertheless,the clay mineralogical composition of the soils was a mixture of kaolinite,irregularly interstratified smectite-illite intergrades (S/I),hydroxyl-Al interlayered 2:1 type clays (HICs),vermiculite,smectite,halloysite and illite along with fine-sized quartz in Abakaliki.The soils of Bende predominantly contained smectite,which was partially interlayered with hydroxyl-A1 and kaolinite.It is suggested that seasonal floodwater has slowed the disintegration of weatherable clay minerals inherited from the shale,while quartz originating from the sandstone is predominant in the fine-sand fraction.Additionally,a possible soil-forming process observed at the both study sites was ferrolysls,which was indicated by a clear decreasing pattern of HICs downward in the soil profiles.The entry of S/I and vertical distribution patterns for a couple of clay minerals in the pedon suggested that the soils in Abakaliki have developed under the significant influence of aeolian dust delivered by the Harmattan.The findings might describe a site-specific deposition pattern of Harmattan dusts as well as hydromorphic soil-forming processes in the wetlands of the inland valleys.

  16. Formes urbaines, modes d’occupation du sol et composition sociale en zone urbaine dense : des relations inattendues à Paris

    Directory of Open Access Journals (Sweden)

    Catherine Rhein

    2014-07-01

    Full Text Available Quelle place occupe la végétation dans les zones urbaines les plus denses ? Selon que l’on soit riche ou pauvre, réside-t-on plutôt dans des quartiers végétalisés ou dans des quartiers dépourvus d’espaces verts publics ou privés ? La place de la végétation dans les zones urbaines denses a été peu étudiée de manière systématique, faute de sources. L’accès à une image Haute Définition de la végétation de Paris a permis la constitution d’une base de données sur les modes d’occupation du sol et sur les générations de tissu urbain dans Paris. Cette base a été complétée par des données sociodémographiques. Trois grands paradoxes sont mis en lumière, sur les quartiers haussmanniens, aisés, mais peu végétalisés, sur les gentrifieurs, ou plutôt sur un segment précis d’entre eux, celui des professionnels de l’information, des arts et des spectacles, concentrés dans les quartiers les moins végétalisés de la capitale, enfin sur les retraités, pauvres ou riches, concentrés aujourd’hui dans les quartiers les plus végétalisés. Ces informations sur les modes d’occupation du sol permettent ainsi de nouvelles interprétations des processus de gentrification et, de manière plus générale, des transformations du tissu urbain et des couches sociales.

  17. The Study of the Chemical Composition of Essential Oils Mentha Piperita L. are Grown in Non-Chernozem Zone of Russia

    Directory of Open Access Journals (Sweden)

    L. SUSHKOVA

    2014-07-01

    Full Text Available By gas-liquid chromatography and mass spectrometry has been investigated the composition of essential oils and the change in the ontogenesis and exogenous effects on the plant Mentha piperita L. drugs retardant type. With the introduction of oil crops from the southern regions to the more northern regions of the component composition of the essential oil practically does not change. There are only minor variations in the content of some terpenoids oils. Exogenous preharvest treatment plant growth regulators can in some cases deliberately influence the activity of various terpenoid biosynthesis and increase the content of the most valuable components of the essential oil.Content and composition of EM is largely determined by factors such as age and leaves of plants, as well as different climatic cal, soil and agronomic conditions. Processing plants different phytoregulators also affects the content and composition of oil. Biosynthesis of terpenoids polyenzyme performed in centers, the activity and the nature of which is determined primarily genetic characteristics of plants, in addition, the activity of certain enzymes of these centers is under the control of hormonal balance and changes in ontogeny, as well as under the influence of exogenous factors.It is shown that the formation of the maximum bioefficiency in ontogeny of aromatic plants, it is advisable to use a two-stage technology to grow them. Plants producing terpenoids of essential oils, the initial step is to create the conditions for the formation of the maximum yield of aboveground mass of plants, including the use of synthetic plant growth regulators. In the second stage "biosynthetic" upon the occurrence of the reproductive phase before harvesting plants, we recommend that inhibit the growth of phytoregulators retardant type. In this case, we observe stimulation accumulation in aboveground mass of secondary metabolites. Inhibition of growth in the preharvest period, aromatic plants

  18. Redetermination of piperidinium hydrogen sulfide structure

    Science.gov (United States)

    Andras, Maria T.; Hepp, Aloysius F.; Fanwick, Phillip E.; Duraj, Stan A.; Gordon, Edward M.

    1994-01-01

    The presence of adventitious water in a reaction between dicyclopentamethylene thiuram-disulfide (C5H10NCS2)(sub 2) and a picoline solution of tricyclopentadienyl indium(III) (C5H5)(sub 3). It resulted in the formation of piperidinium hydrogen sulfide (C5H13NS). The piperidinium hydrogen sulfide produced in this way was unambiguously characterized by X-ray crystallography. The structure determination showed that the piperidinium hydrogen sulfide crystal (MW = 119.23 g/mol) has an orthorhombic (Pbcm) unit cell whose parameters are: a = 9.818(2), b = 7.3720(1), c = 9.754(1) A, V = 706.0(3) A(exp 3), Z=4. D(sub chi) = 1.122 g cm(exp -3), Mo K(alpha) (lamda = 0.71073), mu= 3.36 cm(exp -1), F(000) = 264.0, T =293 K, R = 0.036 for 343 reflections with F(sub O)(sup 2) greater than 3 sigma (F(sub O)(sup 2)) and 65 variables. The compound consists of (C5H10NH2)(+) cations and (SH)(-) anions with both species residing on crystallographic mirror planes. N-H -- S hydrogen bonding contributes to the interconnection of neighboring piperidinium components of the compound.

  19. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.

    2004-01-01

    experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...... differences in KLaH2S at pH values between 4.5 and 8.0 became larger as the turbulence level increased, whereas those at pH between 4.5 and 7.0 did not statistically show any change. At constant pH, KLaH2S/KLaO2 was observed not to be dependent on the turbulence range studied. KLaH2S/KLaO2 ratio was 0...

  20. Uranium, thorium and REE partitioning into sulfide liquids: Implications for reduced S-rich bodies

    Science.gov (United States)

    Wohlers, Anke; Wood, Bernard J.

    2017-05-01

    We have performed experiments at 1.5 GPa over the temperature range 1400-2100 °C to determine the partitioning of lithophile elements (U, Th, Eu, Sm, Nd, Zr, La, Ce, Yb) between sulfide liquid, low-S metals and silicate melt. The data demonstrate pronounced increases in partitioning of all the lithophile elements into sulfide at very low FeO contents (10 in some cases. Similarly DSm may be >2 under the same conditions of low silicate FeO. This strong partitioning behaviour is found only be important in S-rich metals, however because the observed effect of low FeO on partitioning is uniquely confined to metallic melts close to stoichiometric FeS in composition.

  1. A chemostratigraphic study of the Campanian Ignimbrite eruption (Campi Flegrei, Italy): Insights on magma chamber withdrawal and deposit accumulation as revealed by compositionally zoned stratigraphic and facies framework

    Science.gov (United States)

    Fedele, L.; Scarpati, C.; Sparice, D.; Perrotta, A.; Laiena, F.

    2016-09-01

    Petrochemical analyses of juvenile samples from twenty stratigraphic sections of the Campanian Ignimbrite medial deposits, located from 30 to 79 km from the vent, are presented here. Sampling has accurately followed a well-defined stratigraphic framework and the new component facies scheme. The Campanian Ignimbrite succession is formed by a basal plinian pumice fall deposit, overlain by a complex architecture of pyroclastic density current deposits emplaced from a single sustained pyroclastic density current through a mechanism of vertical and lateral accretion. The deposit is broadly zoned, from more evolved trachyte at its base to less evolved trachyte at its top, and is similarly less evolved with increasing distance from the area of emission. Irregular chemical trends are locally observed and interpreted to represent only a limited, "patchy" record of the entire vertical geochemical trend. The petrochemical variation observed horizontally was ascribed to changes in the flow dynamics and interaction between the advancing flow and the underlying topography. The results of this study were used to propose a unified volcanological-petrological model for the Campanian Ignimbrite eruption, taking into account the emplacement of both the proximal (i.e., the "Breccia Museo" formation) and medial deposits.

  2. Comparison of the stable-isotopic composition of soil water collected from suction lysimeters, wick samplers, and cores in a sandy unsaturated zone

    Science.gov (United States)

    Landon, M. K.; Delin, G. N.; Komor, S. C.; Regan, C. P.

    1999-10-01

    Soil water collected from suction lysimeters and wick samplers buried in the unsaturated zone of a sand and gravel aquifer and extracted from soil cores were analyzed for stable oxygen and hydrogen isotope values. Soil water isotopic values differed among the three sampling methods in most cases. However, because each sampling method collected different fractions of the total soil-water reservoir, the isotopic differences indicated that the soil water at a given depth and time was isotopically heterogeneous. This heterogeneity reflects the presence of relatively more and less mobile components of soil water. Isotopic results from three field tests indicated that 95-100% of the water collected from wick samplers was mobile soil water while samples from suction lysimeters and cores were mixtures of more and less mobile soil water. Suction lysimeter samples contained a higher proportion of more mobile water (15-95%) than samples from cores (5-80%) at the same depth. The results of this study indicate that, during infiltration events, soil water collected with wick samplers is more representative of the mobile soil water that is likely to recharge ground water during or soon after the event than soil water from suction lysimeters or cores.

  3. Organization of the human mitochondrial hydrogen sulfide oxidation pathway.

    Science.gov (United States)

    Libiad, Marouane; Yadav, Pramod Kumar; Vitvitsky, Victor; Martinov, Michael; Banerjee, Ruma

    2014-11-07

    Sulfide oxidation is expected to play an important role in cellular switching between low steady-state intracellular hydrogen sulfide levels and the higher concentrations where the physiological effects are elicited. Yet despite its significance, fundamental questions regarding how the sulfide oxidation pathway is wired remain unanswered, and competing proposals exist that diverge at the very first step catalyzed by sulfide quinone oxidoreductase (SQR). We demonstrate that, in addition to sulfite, glutathione functions as a persulfide acceptor for human SQR and that rhodanese preferentially synthesizes rather than utilizes thiosulfate. The kinetic behavior of these enzymes provides compelling evidence for the flow of sulfide via SQR to glutathione persulfide, which is then partitioned to thiosulfate or sulfite. Kinetic simulations at physiologically relevant metabolite concentrations provide additional support for the organizational logic of the sulfide oxidation pathway in which glutathione persulfide is the first intermediate formed.

  4. Sulfide scaling in low enthalpy geothermal environments; A survey

    Energy Technology Data Exchange (ETDEWEB)

    Criaud, A.; Fouillac, C. (Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France))

    1989-01-01

    A review of the sulfide scaling phenomena in low-temperature environments is presented. While high-temperature fluids tend to deposit metal sulfides because of their high concentrations of dissolved metals and variations of temperature, pressure and fluid chemistry, low temperature media are characterized by very low metal content but much higher dissolved sulfide. In the case of the goethermal wells of the Paris Basin, detailed studies demonstrate that the relatively large concentrations of chloride and dissolved sulfide are responsible for corrosion and consequent formation of iron sulfide scale composed of mackinawite, pyrite and pyrrhotite. The effects of the exploitation schemes are far less important than the corrosion of the casings. The low-enthalpy fluids that do not originate from sedimentary aquifers (such as in Iceland and Bulgaria), have a limited corrosion potential, and the thin sulfide film that appears may prevent the progress of corrosion.

  5. Measurement of plasma hydrogen sulfide in vivo and in vitro

    OpenAIRE

    Shen, Xinggui; Pattillo, Christopher B.; Pardue, Sibile; Bir, Shyamal C.; Wang, Rui; Kevil, Christopher G.

    2011-01-01

    The gasotransmitter hydrogen sulfide is known to regulate multiple cellular functions during normal and pathophysiological states. However, a paucity of concise information exists regarding quantitative amounts of hydrogen sulfide involved in physiological and pathological responses. This is primarily due to disagreement among various methods employed to measure free hydrogen sulfide. In this article, we describe a very sensitive method of measuring the presence of H2S in plasma down to nanom...

  6. Roasting of a sulfide polymetallic concentrate in a fluidized bed furnace

    Science.gov (United States)

    Savinova, Yu. A.; Popov, V. A.; Portov, A. B.; Tsemekhman, L. Sh.

    2014-05-01

    Three series of experiments on oxidizing roasting of sulfide polymetallic concentrates in a laboratory fluidized bed furnace are performed to develop an economically efficient technology of processing the sulfide polymetallic ore concentrate of the Artem'evsk deposit (Kazakhstan). The composition of the initial concentrate and the products of its oxidizing roasting are studied. The mineral composition of the concentrate is determined, and it demonstrates that this material tends toward intense spinel formation under oxidizing roasting conditions. The main structural constituents of the cinder are found to be sulfate-spinel conglomerates and oxide and sulfide particles. The possible ways of formation of these constituents are discussed using the obtained experimental data, the existing theoretical concepts, and the results of thermodynamic analysis. The calculations are performed using the FactSage software package and database. The formation of oxide and spinel components are found to be caused by both direct oxidation of sulfide minerals (primary processes) and the interaction of primary products with sulfuric anhydride and each other (secondary processes). In turn, all sulfates in the cinder are the products of secondary processes, and primary sulfate formation does not take place in roasting under the chosen conditions. Spinels cannot be completely removed from the cinder using their sulfation because of predominant consumption of sulfuric anhydride for interaction with oxide components. The optimum roasting conditions that ensure the formation of the best cinder for subsequent hydrometallurgical processing are chosen on the basis of the obtained data. The degree of extraction of nonferrous metals achieved upon leaching of the cinder is 94-96 wt %.

  7. Comparison of Polythionates as Precursors for the Formation of Thallium Sulfide Layers

    Directory of Open Access Journals (Sweden)

    Vitalijus JANICKIS

    2011-11-01

    Full Text Available The processes of obtaining layers of thallium, sulfides, TlxSy, by the sorption-diffusion method on polyamide 6 using solutions of lower polythionates - sodium trithionate and tetrathionate, Na2S3O6, Na2S4O6, potassium pentathionate, K2S5O6, and of dodecathionic acid, H2S12O6, as precursors of sulfur are compared. The concentration of sorbed sulfur increases with increasing the duration of treatment, the concentration and temperature of precursor solution. It rather significantly also depends on the nature - sulfurity of polythionate, i. e. on the number of sulfur atoms in the polythionate anion: effectiveness of sulfurization using solutions of dodecathionic acid is significantly higher than that of lower polythionates. Thallium sulfide layers are formed on the surface of polyamide after the treatment of sulfurized polymer with Tl(I salt solution. The concentration of thallium in the layer increases with the increase of initial sulfurization duration and in case of H2S12O6 solution used - on the temperature of this process. The results of X-ray diffraction analysis confirmed the formation of thallium sulfide layers in the surface of polyamide 6. The phase composition of layer changes depending on the conditions of initial treatment in a H2S12O6 solution. Five thallium sulfide phases, two forms of TlS, Tl2S2, Tl4S3 and Tl2S5 were identified in the composition of the layers treated for different time with a solution of dodecathionic acid at the temperature of 20 °C and 30 °C and then with Tl(I salt solution by X-ray diffraction but the maxima of TlS and Tl2S5 phases predominate in the diffractograms.http://dx.doi.org/10.5755/j01.ms.17.4.774

  8. Origin and fate of sulfide liquids in hotspot volcanism (La Réunion): Pb isotope constraints from residual Fe-Cu oxides

    Science.gov (United States)

    Vlastélic, I.; Gannoun, A.; Di Muro, A.; Gurioli, L.; Bachèlery, P.; Henot, J. M.

    2016-12-01

    Immiscible sulfide liquids in basaltic magmas play an important role in trace metal transport and the sulfur budget of volcanic eruptions. However, sulfides are transient phases, whose origin and fate are poorly constrained. We address these issues by analyzing sulfide destabilization products preserved in lavas from La Réunion Island. Iron oxide globules and coatings, typically 20-80 μm in size, were found to occur in vesicles of differentiated lavas from Piton des Neiges, and recent pumice samples from Piton de la Fournaise. Field and mineralogical evidence indicates that the iron oxides are syn-eruptive phases not resulting from hydrothermal processes. Samples were first studied by Scanning Electron Microscopy. The globules were separated, whereas the smaller spherules and coatings were concentrated by magnetic sorting and acid leaching, and samples were processed through wet chemistry. The Fe oxide phases comprise 49-74 wt.% Fe, 26-40 wt.% O, and up to 6 wt.% Cu, 811 ppm Ni, 140 ppm Bi, and 8.5 ppm Pb. Compared to the host lava, Cu, Ni, and Bi are enriched by a factor of 101-103. Systematic Pb isotope disequilibrium (between 500 ppm and 2.9% for 206Pb/204Pb) exists between Fe oxides and host rocks, with Fe oxides generally displaying less radiogenic ratios. Unradiogenic Pb is a typical signature of sulfide, which tends to concentrate Pb, but not its parent elements U and Th. Thus, both the chemical and isotopic compositions of the vesicle-hosted Fe oxides suggest that they are more or less direct products of the destabilization of immiscible sulfide liquids. Although Pb dominantly partitions into the gas phase during sulfide breakdown, the original Pb isotope signature of sulfide is preserved in the residual oxide. The composition estimated for the parent sulfides (206Pb/204Pb = 18.20-18.77, 207Pb/204Pb = 15.575, and 208Pb/204Pb = 38.2-38.8) precludes a genetic link with the La Réunion plume, and suggests a lithospheric or crustal origin. It is estimated

  9. Limitation of Sulfide Capacity Concept for Molten Slags

    Science.gov (United States)

    Jung, In-Ho; Moosavi-Khoonsari, Elmira

    2016-04-01

    The sulfide capacity concept has been widely used in pyrometallurgy to define sulfur removal capacities of slags. Typically, the sulfide capacity is considered to be a unique slag property depending only on temperature regardless of partial pressures of oxygen and sulfur. In the present study, it is demonstrated that sulfide capacities of slags in particular those of Na2O-containing slags can vary with partial pressures of oxygen and sulfur due to large solubility of sulfide in Na2O-containing slag systems.

  10. Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy.

    Science.gov (United States)

    Song, Kai; Wang, Fen; Li, Qian; Shi, Yong-Bing; Zheng, Hui-Fen; Peng, Hanjing; Shen, Hua-Ying; Liu, Chun-Feng; Hu, Li-Fang

    2014-06-01

    Hydrogen sulfide has recently been found decreased in chronic kidney disease. Here we determined the effect and underlying mechanisms of hydrogen sulfide on a rat model of unilateral ureteral obstruction. Compared with normal rats, obstructive injury decreased the plasma hydrogen sulfide level. Cystathionine-β-synthase, a hydrogen sulfide-producing enzyme, was dramatically reduced in the ureteral obstructed kidney, but another enzyme cystathionine-γ-lyase was increased. A hydrogen sulfide donor (sodium hydrogen sulfide) inhibited renal fibrosis by attenuating the production of collagen, extracellular matrix, and the expression of α-smooth muscle actin. Meanwhile, the infiltration of macrophages and the expression of inflammatory cytokines including interleukin-1β, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in the kidney were also decreased. In cultured kidney fibroblasts, a hydrogen sulfide donor inhibited the cell proliferation by reducing DNA synthesis and downregulating the expressions of proliferation-related proteins including proliferating cell nuclear antigen and c-Myc. Further, the hydrogen sulfide donor blocked the differentiation of quiescent renal fibroblasts to myofibroblasts by inhibiting the transforming growth factor-β1-Smad and mitogen-activated protein kinase signaling pathways. Thus, low doses of hydrogen sulfide or its releasing compounds may have therapeutic potentials in treating chronic kidney disease.

  11. INVESTIGATION OF THIN FILM CADMIUM SULFIDE SOLAR CELLS.

    Science.gov (United States)

    SOLAR CELLS , *CADMIUM COMPOUNDS, FILMS, SULFIDES, VAPOR PLATING, VACUUM APPARATUS, SINGLE CRYSTALS, TITANIUM, COPPER COMPOUNDS, CHLORIDES, INDIUM, MOLYBDENUM, SILICON COMPOUNDS, MONOXIDES, SURFACE PROPERTIES, ENERGY CONVERSION.

  12. Influence of iron on sulfide inhibition in dark biohydrogen fermentation.

    Science.gov (United States)

    Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Nakhla, George

    2012-12-01

    Sulfide impact on biohydrogen production using dark fermentation of glucose at 37 °C was investigated. Dissolved sulfide (S(2-)) at a low concentration (25mg/L) increased biohydrogen production by 54% relative to the control (without iron addition). Whereas on initial dissolved S(2-) concentration of 500 mg/L significantly inhibited the biohydrogen production with total cumulative biohydrogen decreasing by 90% compared to the control (without iron addition). At sulfide concentrations of 500 mg S(2-)/L, addition of Fe(2+) at 3-4 times the theoretical requirement to precipitate 100% of the dissolved S(2-) entirely eliminated the inhibitory effect of sulfide.

  13. Cherts from the Yangla copper deposit, western Yunnan Province: geochemical characteristics and relationship with massive sulfide mineralization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Four layers of cherts were found for the first time in the Yanglacopper deposit, western Yunnan Province. The cherts possessed the following geochemical characteristics: ① Low TiO2 and Al2O3 contents, but high ore-forming element (e.g. Cu, Au, Ag) contents; ② low total REE contents and clear negative Eu anomalies when normalized to chondrite similar to the REE contents and distribution patterns of associated massive sulfide ores; ③ silicon isotopic compositions of cherts in the Yangla deposit being the same as cherts and geyserite of hot-water sedimentary origin; ④ lead and sulfur isotopic compositions of cherts in the Yangla deposit being similar to those of the massive sulfide ores in the Yangla deposit; ⑤ Rb-Sr isochron age of cherts from the Yangla deposit being identical with that of host strata. Hence, we conclude that the cherts in the Yangla deposit are of hot-water sedimentary origin, which have a close relationship with the massive sulfide ores. The discovery of hydrothermal cherts from the Yangla copper deposit provides further evidence for the hydrothermal exhalative origin of the massive sulfide deposits.

  14. MEASURING METAL SULFIDE COMPLEXES IN OXIC RIVER WATERS WITH SQUARE WAVE VOLTAMMETRY. (R825395)

    Science.gov (United States)

    A sulfide identification protocol was developed to quantify specific metal sulfides that could exist in river water. Using a series of acid additions, nitrogen purges, and voltammetric analyses, metal sulfides were identified and semiquantified in three specific gr...

  15. Authigenic mineral formation in fluid permeability zones in the West Siberia Permafrost

    Science.gov (United States)

    Kurchatova, A. N.; Melnikov, V. P.; Rogov, V. V.; Slagoda, E. A.

    2016-06-01

    Basic chemical and mineralogical anomalies in permafrost caused by hydrocarbon migration are considered. Direct evidence for bacterial oxidation of light hydrocarbons, primarily methane, were first obtained in fluid permeability zones in the permafrost as a stepwise formation of authigenic minerals such as iron sulfides and oxides, carbonates, silicates, and gypsum.

  16. Toxicological analysis of 17 autopsy cases of hydrogen sulfide poisoning resulting from the inhalation of intentionally generated hydrogen sulfide gas.

    Science.gov (United States)

    Maebashi, Kyoko; Iwadate, Kimiharu; Sakai, Kentaro; Takatsu, Akihiro; Fukui, Kenji; Aoyagi, Miwako; Ochiai, Eriko; Nagai, Tomonori

    2011-04-15

    Although many cases of fatal hydrogen sulfide poisoning have been reported, in most of these cases, it resulted from the accidental inhalation of hydrogen sulfide gas. In recent years, we experienced 17 autopsy cases of fatal hydrogen sulfide poisoning due to the inhalation of intentionally generated hydrogen sulfide gas. In this study, the concentrations of sulfide and thiosulfate in blood, urine, cerebrospinal fluid and pleural effusion were examined using GC/MS. The sulfide concentrations were blood: 0.11-31.84, urine: 0.01-1.28, cerebrospinal fluid: 0.02-1.59 and pleural effusion: 2.00-8.59 (μg/ml), while the thiosulfate concentrations were blood: 0-0.648, urine: 0-2.669, cerebrospinal fluid: 0.004-0.314 and pleural effusion: 0.019-0.140 (μmol/ml). In previous reports, the blood concentration of thiosulfate was said to be higher than that of sulfide in hydrogen sulfide poisoning cases, although the latter was higher than the former in 8 of the 14 cases examined in this study. These results are believed to be strongly influenced by the atmospheric concentration of hydrogen sulfide the victims were exposed to and the time interval between exposure and death.

  17. Cupriavidus necator H16 uses flavocytochrome c-sulfide dehydrogenase to oxidize self-produced and spiked sulfide.

    Science.gov (United States)

    Lü, Chuanjuan; Xia, Yongzhen; Liu, Daixi; Zhao, Rui; Gao, Rui; Liu, Honglei; Xun, Luying

    2017-09-01

    Heterotrophic bacteria producing sulfide (H2S, HS(-), and S(2-)) during aerobic growth is a common phenomenon. Some with sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO) can oxidize self-produced sulfide to sulfite and thiosulfate, but others without these enzymes will release sulfide into the medium, from which H2S can volatilize into the gas phase. Here, we report Cupriavidus necator H16 with the fccAB genes, encoding flavocytochrome c-sulfide dehydrogenases (FCSDs), also oxidized self-produced H2S. The mutant with fccAB being deleted accumulated and released H2S. When fccAB were expressed in a Pseudomonas aeruginosa strain Pa3K with deletions of its sqr and pdo genes, the recombinant rapidly oxidized sulfide to sulfane sulfur. When PDO was also cloned into the recombinant, the recombinant with both FCSD and PDO oxidized sulfide to sulfite and thiosulfate. Thus, the proposed pathway is similar to the pathway catalyzed by SQR and PDO, in which FCSD oxidizes sulfide to polysulfide, polysulfide spontaneously reacts with GSH to produce GSSH, and PDO oxidizes GSSH to sulfite, which chemically reacts with polysulfide to produce thiosulfate. About 20.6% of sequenced bacterial genomes contain SQR, and only 3.9% contain FCSD. This is not a surprise since SQR is more efficient in conserving energy because it passes electrons from sulfide oxidation into the electron transport chain at the quinone level, while FCSD passes electrons to cytochrome c The transport of electrons from the latter to O2 conserves less energy. FCSDs are grouped into three subgroups, well conserved at taxonomic levels. Thus, our data show the diversity in sulfide oxidation by heterotrophic bacteria.Importance Heterotrophic bacteria with SQR and PDO can oxidize self-produced sulfide and do not release H2S into the gas phase. C. necator H16 has FCSD but not SQR, and it does not release H2S. We confirmed that the bacterium used FCSD for the oxidation of self-produced sulfide. The

  18. Evidence supporting biologically mediated sulfide oxidation in hot spring ecosystems

    Science.gov (United States)

    Cox, A. D.; Shock, E.

    2011-12-01

    The sulfide concentration of fluids in hydrothermal ecosystems is one of several factors determining the transition to microbial photosynthesis (Cox et al., 2011, Chem. Geol. 280, 344-351). To investigate the loss of sulfide in Yellowstone hot spring systems, measurements of total dissolved sulfide with respect to time were made in incubation experiments conducted on 0.2-micron filtered (killed controls) vs. unfiltered hot spring water at locations with three different pH:sulfide combinations (pH 2.5 with 50 μM sulfide, 5.2 with 5.6 μM sulfide, and 8.3 with 86 μM sulfide). At the higher pH values, the experiments yielded similar rates of sulfide loss in filtered and unfiltered water of approximately 0.8 (pH 5.2) and 7.6 nmol sulfide L-1s-1 (pH 8.3). At the acidic spring, the unfiltered water lost sulfide at a rate 1.6 times that of the filtered water (8.2 vs. 5 nmol sulfide L-1s-1). These results suggest that the pelagic biomass at the pH 5.2 and 8.3 springs may not affect sulfide loss, whereas in the pH 2.5 spring there appears to be an effect. In addition, the incubation of filamentous biomass with unfiltered water increased the rate of sulfide loss by approximately two-fold at a pH of 2.5 (59 vs. 31 nmol L-1s-1; Cox et al., 2011), five-fold at a pH of 5.2 (3.9 vs. 0.8 nmol sulfide L-1s-1), and barely increased the rate of sulfide loss at a pH of 8.3 (9.1 vs. 8.4 nmol sulfide L-1s-1). Sulfide is predominately present as HS- at a pH of 8.3, which may not be taken up as easily by microorganisms as the H2S (aq) that dominates sulfide speciation at pH 2.5 and 5.2. That the loss of sulfide at acidic pH is due to biotic rather than abiotic factors is further supported by studies with whole mat samples that show greater sulfide consumption than killed controls (D'Imperio et al., 2008, AEM 74, 5802-5808). Taken together, the results of these experiments suggest that the majority of sulfide oxidation occurs in the filamentous biomass of hot spring ecosystems, although

  19. Technetium Reduction and Permanent Sequestration by Abiotic and Biotic Formation of Low-Solubility Sulfide Mineral Phases

    Energy Technology Data Exchange (ETDEWEB)

    Tratnyek, Paul G. [Oregon Health & Science Univ., Beaverton, OR (United States); Tebo, Bradley M. [Oregon Health & Science Univ., Beaverton, OR (United States); Fan, Dimin [Oregon Health & Science Univ., Beaverton, OR (United States); Anitori, Roberto [Oregon Health & Science Univ., Beaverton, OR (United States); Szecsody, Jim [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jansik, Danielle [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-11-14

    One way to minimize the mobility of the TcVII oxyanion pertechnetate (TcO4-) is to effect reduction under sulfidogenic conditions (generated abiotically by Fe0 or biotically) to form TcSx, which is significantly slower to oxidize than TcIVO2. In sediment systems, TcSx and other precipitates may oxidize more slowly due to oxygen diffusion limitations to these low permeability precipitate zones. In addition, the TcO4- reduction rate may be more rapid in the presence of sediment because of additional reductive surface phases. This project aims to provide a fundamental understanding of the feasibility of immobilization of TcO4- as TcSx in the vadose zone or groundwater by application nano zero-valent iron (nZVI), and sulfide or sulfate. Biotic batch experiments have used the sulfate-reducing bacterium (SRB) Desulfotomaculum reducens. The iron sulfide mineral mackinawite was generated under these conditions, while vivianite was formed in nZVI only controls. The sulfide/bacteria-containing system consistently reduced aqueous pertechnetate rapidly (> 95% in the first hour), a rate similar to that for the sulfide-free, nZVI only system. Reduced Tc (aged for 3 months) generated in both SRB/nZVI systems was highly resistant to reoxidation. In reduced samples, Tc was found associated with solid phases containing Fe and S (D. reducens/nZVI) or Fe (nZVI only). Experiments using D. reducens without nZVI provided some additional insights. Firstly, stationary phase cultures were able to slowly reduce pertechnetate. Secondly, addition of pertechnetate at the beginning of cell growth (lag phase) resulted in a faster rate of Tc reduction, possibly indicating a direct (e.g. enzymatic) role for D. reducens in Tc reduction. Abiotic batch experiments were conducted with Na2S as the sulfide source. Pertechnetate reduction was

  20. GROWTH PERFORMANCE EVALUATION OF JUVENILES OF Archachatina marginata OVUM AND Archachatina marginata saturalis SNAIL SUBSPECIES FED FORAGES AND THEIR NUTRIENT COMPOSITION IN CROSS RIVER RAINFOREST ZONE, NIGERIA

    Directory of Open Access Journals (Sweden)

    J. A. UBUA

    2013-11-01

    Full Text Available The growth performance characteristics of juveniles of Archachatina marginata ovum and Archachatina marginata saturalis snail subspecies were evaluated using a feeding regime of forages. The forages of choice utilized were: Sweet potato (T1, Cocoyam (T2, Banana (T3, pawpaw (T4 and Okra (T5 respectively. The nutrient composition of these forages was equally determined. Results from this study revealed that juveniles of Archachatina marginata ovum recorded better feed intake than those of Archachatina marginata saturalis. The weight gain showed significant difference (P0.05 in Ether extract among the forages. Result of CF showed relative increase across the five forages. Banana leaves had the highest value and was significantly different (P<0.05 from those of sweet Potato and pawpaw leaves. The highest NFE content was recorded in sweet potato leaves. There was significant difference (P<0.05 in the Ash content among all the forages except sweet potato. Results from this study were within the normal proximate values of these forages and confirmed that these leaves (plant protein sources are good forages for farm animals especially micro-livestock like snails and can enhanced optimum growth characteristics.

  1. GIS-based colour composites and overlays to delineate heavy metal contamination zones in the shallow alluvial aquifers, Ankaleshwar industrial estate, south Gujarat, India

    Science.gov (United States)

    Kumar, Suyash; Shirke, K. D.; Pawar, N. J.

    2008-03-01

    In an attempt to delineate heavy metal contamination precincts and to evaluate the extent and degree of toxic levels, besides their possible sources, 38 water samples from Ankaleshwar Industrial Estate, south Gujarat, India were analyzed. By clutching geochemical analyses and GIS-based colour composites areas depicting anomalously high concentration of heavy metals (Mo, Zn, Pb, Ni, Co, Cd, etc.) in the groundwater were revealed. The multicomponent overlays in grey-scale facilitated in identifying situates of heavy metal ‘hot spots’, and lateral protuberances of the contamination plume around defile stretch of the main stream Amla Khadi flowing through the area. The multiple pollution plumes emerging from other parts of the area further coincide with effluent laden streams and small channels indicating industrial establishments as major sources of groundwater contamination. Influent nature of the streams, accelerated infiltration process, high mass influx and shallow groundwater table are the factors conducive for easy access of heavy metals to the phreatic aquifers affecting over 20 km2 area. On the basis of P/ U ratios (concentration of metals in polluted water to unpolluted water), geogenic and anthropogenic sources have been identified. Very high levels of technogenic elements present in the ground water raise concerns about possible migration into food crops, as the area is an important horticultural locale and is highly cultivated.

  2. Growth variability and stable isotope composition of two larval carangid fishes in the East Australian Current: The role of upwelling in the separation zone

    Science.gov (United States)

    Syahailatua, Augy; Taylor, Matthew D.; Suthers, Iain M.

    2011-03-01

    The larvae of two carangid fishes, silver trevally ( Pseudocaranx dentex) and yellowtail scad ( Trachurus novaezelandiae), were compared among coastal water masses and the East Australian Current (EAC). Samples followed a north to south gradient including a southern region of upwelling, generated as the EAC separated from the coast. Mean larval carangid densities were greater in the mixed layer (10-30 m) than the surface, but there was no difference between inshore and offshore stations or along latitudinal gradients. Overall, P. dentex recent larval growth over two days pre-capture was faster than T. novaezelandiae, and faster at inshore, coastal stations than in the EAC. Integrated larval growth rate (mm d -1) was usually faster at inshore stations for both species. T. novaezelandiae were enriched in both nitrogen (δ 15N) and carbon (δ 13C) stable isotopes relative to P. dentex. Larvae of both species captured within the upwelling region were enriched in δ 15N and depleted in δ 13C relative to other sites. Recent larval growth had a significant positive relationship with fluorescence (as a proxy of chlorophyll a biomass), and integrated larval growth rate had a significant positive relationship with fluorescence and larval isotope (δ 15N) composition. Recent and integrated growth of larval T. novaezelandiae and P. dentex was enhanced by EAC separation and upwelling, and also in coastal water; stimulated by food availability, and potentially through exploitation of a different trophic niche.

  3. A new interpretation for the origin of the Norilsk type PGE–Cu–Ni sulfide deposits

    Directory of Open Access Journals (Sweden)

    V.I. Starostin

    2011-10-01

    Full Text Available The origin of PGE–Cu–Ni sulfide deposits of Norilsk and Talnakh located in the northwest flank of the Triassic basalt trap formation of Siberia is considered. It is shown that ore elements of these deposits (probably, except Fe are derived from the crust rather than from the mantle. They entered the basalts owing to a remobilization (recycling of ore elements from the Paleoproterozoic sediments and from the rocks of the Siberian platform’s basement. Prospecting criteria for similar deposits are as follows: (1 a presence of a large Paleoproterozoic aulacogen and a related magmatic sulfide Cu–Ni mineralization; (2 a confinement of perspective areas to troughs associated with long-lived deep fault zones; (3 association with mobile orogenic belts, island-arc systems and tectonomagmatic activation zones; (4 temporal association with boundaries of global periods characterized by active processes of continental breakup and large-scale trap magmatism. A combination of several factors (the first one is obligatory is favorable for the discovery of a large ore body.

  4. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco.

    Science.gov (United States)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild; Nielsen, Asbjørn Haaning

    2015-11-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit with some uncertainty. It was concluded that the model could be applied for the purpose in mind.

  5. The behavior of molybdenum and its isotopes across the chemocline and in the sediments of sulfidic Lake Cadagno

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Anbar, Ariel; Gordon, Gwyneth

    2010-01-01

    concentrations correlate with total organic carbon and yield Mo levels which are two orders of magnitude higher than typical crustal values found in rocks from the catchment area. Solid-phase Mo in the sediment shows a slightly positive d98Mo trend with depth, from d98Mo = 1.2&to 1.4&while the pore waters show...... to H2S 200 lM in the bottom waters (or about 300 lM total sulfide: RS2=H2S + HS + S2). We find that Mo behaves conservatively in the oxic zone and non-conservatively in the sulfidic zone, where dissolved Mo concentrations decrease from 14 nM to 2–8 nM across this transition. Dissolved Mo in the upper...... collect particles increasingly enriched in Mo with depth, with d98Mo values significantly fractionated at 0.8& to 1.2& both near the chemocline and in the deepest trap. Suspended particulates in the sulfidic waters carry lighter Mo than the ambient dissolved Mo pool by 0.3–1.5&. Sedimentary Mo...

  6. The behavior of molybdenum and its isotopes across the chemocline and in the sediments of sulfidic Lake Cadagno, Switzerland

    DEFF Research Database (Denmark)

    Dahl, Tais W.; Anbar, Ariel D.; Gordon, Gwyneth W.

    2010-01-01

    concentrations correlate with total organic carbon and yield Mo levels which are two orders of magnitude higher than typical crustal values found in rocks from the catchment area. Solid-phase Mo in the sediment shows a slightly positive d98Mo trend with depth, from d98Mo = 1.2‰ to 1.4‰ while the pore waters show...... to H2S  200 µM in the bottom waters (or about 300 µM total sulfide: SS2- = H2S + HS- + S2-). We find that Mo behaves conservatively in the oxic zone and non-conservatively in the sulfidic zone, where dissolved Mo concentrations decrease from 14 nM to 2-8 nM across this transition. Dissolved Mo...... collect particles increasingly enriched in Mo with depth, with d98Mo values significantly fractionated at -0.8‰ to -1.2‰ both near the chemocline and in the deepest trap. Suspended particulates in the sulfidic waters carry lighter Mo than the ambient dissolved Mo pool by 0.3-1.5‰. Sedimentary Mo...

  7. Transparent zinc sulfide processed from nanocrystalline powders

    Science.gov (United States)

    Gao, De; Stefanik, Todd S.

    2013-06-01

    Nanocerox produces oxide nanopowders via flame spray pyrolysis that have proven effective in the processing of a host of high quality optical ceramic materials. In order to produce LWIR windows to compete with ZnS, however, oxide materials are not suitable. Nanocerox has therefore developed aqueous synthesis techniques for the production of zinc sulfide nanopowders. The proprietary processing technique allows control of primary particle size, high purity, low levels of agglomeration, and cost effective synthesis. Crystallinity, particle size, and purity of the powders will be presented. Characterization of parts fabricated from these powders via sinter/HIP processing will also be discussed, including optical performance and microstructural characterization.

  8. Iron Sulfide Minerals in Black Sea Sediments

    Science.gov (United States)

    Franke, Christine; Robin, Eric; Henkel, Susann; Courtin-Nomade, Alexandra; Bleil, Ulrich

    2010-05-01

    This study presents a mutidisciplinary geochemical and environmental magnetic approach, integrating advanced mineralogical techniques to better understand the physicochemical syn-sedimentary and post-depositional processes in the anoxic sediments from the northwestern Black Sea. The investigated gravity core GC 214 was retrieved in 2007 during RV METEOR cruise M72/1 west of the Crimean Peninsula in a water depth of 1686 mbsf. Geochemical analyses of the pore water and solid phase indicate non-steady state sedimentation. The oxygen-depleted water column conditions, anaerobic oxidation of methane (AOM), and related microbial-driven sulfate reduction favor a highly complex iron sulfide mineral assemblage in the sediment column. The detailed magnetic susceptibility and remanence measurements indicate an irregularly stratified depth profile showing intervals of particularly high values. Further environmental magnetic analyses of hysteresis loops depict strongly elevated coercivity values for those depth horizons, suggesting metastable ferrimagnetic greigite (Fe3S4) as the main magnetic carrier phase. Automated chemical classification (ACC), using electron dispersive spectrometer (EDS) attached to a JEOL 840 scanning electron microscope (SEM) on dispersed particle samples permitted the absolutequantification of the various present iron mineral phases with depth, identified as greigite (Fe3S4), pyrrhotite (Fe7S8), pyrite (FeS2), and monosulfides (FeS), such as troilite or markasite. The statistically stable ACC analyses were carried out on magnetic extracts and density separates to be able to calculate budgets between the different present iron sulfides. We also obtained excellent correlations between the different iron sulfide concentrations and the magnetic signal, which open the possibility to link the absolute particle concentrations to the magnetic signal. Additional synchrotron based micro-XRD analyses on polished sections yield inside into the details of the

  9. Mercury Sulfide Dimorphism in Thioarsenate Glasses

    OpenAIRE

    KASSEM, Mohammad; Sokolov, Anton; Cuisset, Arnaud,; Usuki, Takeshi; Khaoulani, Sohayb; Masselin, Pascal; Le Coq, David,; Feygenson, M.; Benmore, C. J.; Hannon, Alex,; Neuefeind, J. C.; Bychkov, Eugene

    2016-01-01

    International audience; Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding pattern are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity o...

  10. Zoning Districts, Zoning, Published in 2002, Freelance.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Zoning Districts dataset, was produced all or in part from Hardcopy Maps information as of 2002. It is described as 'Zoning'. Data by this publisher are often...

  11. Trace-element fingerprints of chromite, magnetite and sulfides from the 3.1 Ga ultramafic-mafic rocks of the Nuggihalli greenstone belt, Western Dharwar craton (India)

    Science.gov (United States)

    Mukherjee, Ria; Mondal, Sisir K.; González-Jiménez, José M.; Griffin, William L.; Pearson, Norman J.; O'Reilly, Suzanne Y.

    2015-06-01

    The 3.1 Ga Nuggihalli greenstone belt in the Western Dharwar craton is comprised of chromitite-bearing sill-like ultramafic-mafic rocks that are surrounded by metavolcanic schists (compositionally komatiitic to komatiitic basalts) and a suite of tonalite-trondhjemite-granodiorite gneissic rocks. The sill-like plutonic unit consists of a succession of serpentinite (after dunite)-peridotite-pyroxenite and gabbro with bands of titaniferous magnetite ore. The chromitite ore-bodies (length ≈30-500 m; width ≈2-15 m) are hosted by the serpentinite-peridotite unit. Unaltered chromites from massive chromitites (>80 % modal chromite) of the Byrapur and Bhaktarhalli chromite mines in the greenstone belt are characterized by high Cr# (100Cr/(Cr + Al)) of 78-86 and moderate Mg# (100 Mg/(Mg + Fe2+)) of 45-55. In situ trace-element analysis (LA-ICPMS) of unaltered chromites indicates that the parental magma of the chromitite ore-bodies was a komatiite lacking nickel-sulfide mineralization. In the Ga/Fe3+# versus Ti/Fe3+# diagram, the Byrapur chromites plot in the field of suprasubduction zone (SSZ) chromites while those from Bhaktarhalli lie in the MOR field. The above results corroborate our previous results based on major-element characteristics of the chromites, where the calculated parental melt of the Byrapur chromites was komatiitic to komatiitic basalt, and the Bhaktarhalli chromite was derived from Archean high-Mg basalt. The major-element chromite data hinted at the possibility of a SSZ environment existing in the Archean. Altered and compositionally zoned chromite grains in our study show a decrease in Ga, V, Co, Zn, Mn and enrichments of Ni and Ti in the ferritchromit rims. Trace-element heterogeneity in the altered chromites is attributed to serpentinization. The trace-element patterns of magnetite from the massive magnetite bands in the greenstone belt are similar to those from magmatic Fe-Ti-V-rich magnetite bands in layered intrusions, and magnetites from

  12. Induced polarization imaging applied to exploration for low-sulfidation epithermal Au-Ag deposits, Seongsan mineralized district, South Korea

    Science.gov (United States)

    Han, Man-Ho; Shin, Seung Wook; Park, Samgyu; Cho, Seong-Jun; Kim, Jung-Ho

    2016-10-01

    The determination of mineralization boundaries during mineral exploration for undiscovered low-sulfidation epithermal Au-Ag deposits is a significant challenge because of the extensive survey areas required. Induced polarization (IP) imaging is an effective geophysical technique for the detection of sulfides or clay. Thus, this method is considered useful to determine the boundaries of subsurface mineralization and hydrothermal alteration associated with epithermal deposits. We used 2D and 3D IP imaging to define the silicification and mineralization boundaries of the Moisan deposit in the Seongsan mineralized district, which is geologically well-known. The boundaries of the silicification zone were defined by high resistivity values of 600 Ω-m, and those of the mineralization zone were defined by high global chargeability values of 3 mV V-1. The continuity of the high resistivity anomaly corresponded well to the silicification (quartz veins) exposed in outcrop. In addition, it is geologically reasonable that the chargeability anomaly, ⩾3 mV V-1, associated with the mineralization/hydrothermal alteration zone was concentrated at near-surface depths, and extensively surrounding the resistivity anomaly, ⩾600 Ω-m, associated with the silicification zone.

  13. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    Science.gov (United States)

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  14. Recent findings on sinks for sulfide in gravity sewer networks

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2006-01-01

    summarizes this newly obtained knowledge and emphasizes important implications of the findings. Model simulations of the in-sewer processes important for the sulfur cycle showed that sulfide oxidation in the wetted biofilm is typically the most important sink for dissolved sulfide in gravity sewers. However...