Background electrolytes and pH effects on selenate adsorption using iron-impregnated granular activated carbon and surface binding mechanisms.

PubMed

Zhang, Ning; Gang, Daniel Dianchen; McDonald, Louis; Lin, Lian-Shin

2018-03-01

Iron-impregnated granular activated carbon (Fe-GAC) has been shown effective for selenite adsorptive removal from aqueous solutions, but similar effectiveness was not observed with selenate. This study examined the effects of background electrolytes and pH on selenate adsorption on to Fe-GAC, and surface bindings to elucidate the selenate adsorption mechanisms. The decrease magnitude of selenate adsorption capacity under three background electrolytes followed the order: LiCl > NaCl > KCl, as ionic strength increased from 0.01 to 0.1 M. Larger adsorption capacity differences among the three electrolytes were observed under the higher ionic strengths (0.05 and 0.1 M) than those under 0.01 M. Multiplet peak fittings of high resolution X-ray photoelectron spectra for O1s and Fe2p 3/2 indicated the presence of iron (III) on adsorbent surface. pH variations during the adsorbent preparation within 3-8 in NaCl solutions did not cause appreciable changes in the iron redox state and composition. Raman spectra showed the formation of both monodentate and bidentate inner sphere complexes under pHs <7 and a mixture of outer sphere and inner sphere complexes at pH 8. These results explained the lower selenate adsorption under alkaline conditions. Mechanisms for monodentate and bidentate formations and a stable six-member ring structure were proposed. Two strategies were recommended for modifying Fe-GAC preparation procedure to enhance the selenate adsorption: (1) mixed-metal oxide coatings to increase the point of zero charge (pH zpc ); and (2) ferrous iron coating to initially reduce selenate followed by selenite adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical Forms of Selenium in the Metal-Resistant Bacterium Ralstonia metallidurans CH34 Exposed to Selenite and Selenate

PubMed Central

Sarret, Géraldine; Avoscan, Laure; Carrière, Marie; Collins, Richard; Geoffroy, Nicolas; Carrot, Francine; Covès, Jacques; Gouget, Barbara

2005-01-01

Ralstonia metallidurans CH34, a soil bacterium resistant to a variety of metals, is known to reduce selenite to intracellular granules of elemental selenium (Se0). We have studied the kinetics of selenite (SeIV) and selenate (SeVI) accumulation and used X-ray absorption spectroscopy to identify the accumulated form of selenate, as well as possible chemical intermediates during the transformation of these two oxyanions. When introduced during the lag phase, the presence of selenite increased the duration of this phase, as previously observed. Selenite introduction was followed by a period of slow uptake, during which the bacteria contained Se0 and alkyl selenide in equivalent proportions. This suggests that two reactions with similar kinetics take place: an assimilatory pathway leading to alkyl selenide and a slow detoxification pathway leading to Se0. Subsequently, selenite uptake strongly increased (up to 340 mg Se per g of proteins) and Se0 was the predominant transformation product, suggesting an activation of selenite transport and reduction systems after several hours of contact. Exposure to selenate did not induce an increase in the lag phase duration, and the bacteria accumulated approximately 25-fold less Se than when exposed to selenite. SeIV was detected as a transient species in the first 12 h after selenate introduction, Se0 also occurred as a minor species, and the major accumulated form was alkyl selenide. Thus, in the present experimental conditions, selenate mostly follows an assimilatory pathway and the reduction pathway is not activated upon selenate exposure. These results show that R. metallidurans CH34 may be suitable for the remediation of selenite-, but not selenate-, contaminated environments. PMID:15870319

Effects of selenite and selenate application on distribution and transformation of selenium fractions in soil and its bioavailability for wheat (Triticum aestivum L.).

PubMed

Ali, Fayaz; Peng, Qin; Wang, Dan; Cui, Zewei; Huang, Jie; Fu, Dongdong; Liang, Dongli

2017-03-01

This study investigated the effect of selenate and selenite application on the distribution, transformation of selenium (Se) fractions in soil, as well as the accumulation and availability of Se in each part of wheat plants. A pot experiment was conducted using different concentrations of exogenous selenite or selenate (0.5, 1, 2.5, 5, and 10 mg Se kg -1 soil). Sequential extraction was used to determine the Se fractions in soil, and different models were used to study the behavior of Se in soil and its availability to wheat. Results showed that the distribution and availability of Se in soil and its accumulation in wheat affected both by Se concentrations and forms of exogenous Se. In selenite-treated soil, the proportion of exchangeable and carbonate-bound Se (EXC-Se) (21-42%) fraction increased compared to that in control (12%), while organic matter-bound Se (OM-Se) (23-33%) and Fe-Mn oxide-bound Se (FMO-Se) (11-15%) fractions decreased compare with those in control (37 and 32%, respectively). In selenate-treated soil, soluble-Se (SOL-Se) fraction (30-54%) increased and the OM-Se (9.8-20%) and FMO-Se (4.7-14.2%) fractions decreased compared with those in control. Residual Se (RES-Se) fraction was increased for selenite (7.4-13.4%) and selenate (12-20%) treatments compared with that in control (6.5%). In comparison with control, the available Se (SOL-Se + EXC-Se) fraction increased for both selenite (32-47%) or selenate (54-72%) treatments. Moreover, at the same rate of Se application, Se availability was higher in wheat grown in selenate-treated soils than that in selenite-treated soils. The redistribution index (U ts ) of Se increased from 1 (in control) to 1.2-1.9 and 1.5-2 for selenite and selenate treatments, respectively; additionally, the mobility factor (MF) in selenate-treated soil was 40-90% higher than that in selenite-treated soil. Furthermore, relative bonding intensity (I R ) for both selenite (0.38-0.45) and selenate treatment (0.33-0.41) decreased compared with that in control (0.55). These differences indicated that selenite and selenate varied in terms of fixation capacities in soil, in transformation and distribution of Se in soil fractions, and in their availability to plants. The results of Michaelis-Menten equation demonstrated the high affinity of leaf to selenate, and the high affinity of roots and grains to selenite. Selenate was dominant in nearly all parts of wheat plants and in each application level. However, the affinity of selenite to wheat grains suggests that selenite is a useful Se fertilizer that must be considered in biofortification programs. In-depth studies at the pot and field scales by using different wheat varieties and application methods of Se in different ecological zones must be conducted to elucidate the mechanism and biochemical properties of Se in soil-plant system and ultimately produce Se-rich staple foods.

Lunar and Planetary Science XXXV: Future Missions to the Moon

NASA Technical Reports Server (NTRS)

2004-01-01

This document contained the following topics: A Miniature Mass Spectrometer Module; SELENE Gamma Ray Spectrometer Using Ge Detector Cooled by Stirling Cryocooler; Lunar Elemental Composition and Investigations with D-CIXS X-Ray Mapping Spectrometer on SMART-1; X-Ray Fluorescence Spectrometer Onboard the SELENE Lunar Orbiter: Its Science and Instrument; Detectability of Degradation of Lunar Impact Craters by SELENE Terrain Camera; Study of the Apollo 16 Landing Site: As a Standard Site for the SELENE Multiband Imager; Selection of Targets for the SMART-1 Infrared Spectrometer (SIR); Development of a Telescopic Imaging Spectrometer for the Moon; The Lunar Seismic Network: Mission Update.

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria

NASA Technical Reports Server (NTRS)

Conrad, G. W.; Luer, C. A.; Paulsen, A. Q.; Funderburgh, J. L.; Spooner, B. S. (Principal Investigator)

1993-01-01

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

Immobilization of selenate by iron in aqueous solution under anoxic conditions and the influence of uranyl

NASA Astrophysics Data System (ADS)

Puranen, Anders; Jonsson, Mats; Dähn, Rainer; Cui, Daqing

2009-08-01

In proposed high level radioactive waste repositories a large part of the spent nuclear fuel (SNF) canisters are commonly composed of iron. Selenium is present in spent nuclear fuel as a long lived fission product. This study investigates the influence of iron on the uptake of dissolved selenium in the form of selenate and the effect of the presence of dissolved uranyl on the above interaction of selenate. The iron oxide, and selenium speciation on the surfaces was investigated by Raman spectroscopy. X-ray Absorption Spectroscopy was used to determine the oxidation state of the selenium and uranium on the surfaces. Under the simulated groundwater conditions (10 mM NaCl, 2 mM NaHCO 3, <0.1 ppm O 2) the immobilized selenate was found to be reduced to oxidation states close to zero or lower and uranyl was found to be largely reduced to U(IV). The near simultaneous reduction of uranyl was found to greatly enhance the rate of selenate reduction. These findings suggest that the presence of uranyl being reduced by an iron surface could substantially enhance the rate of reduction of selenate under anoxic conditions relevant for a repository.

Structure, vibrations and quantum chemical investigations of hydrogen bonded complex of bis(1-hydroxy-2-methylpropan-2-aminium)selenate

NASA Astrophysics Data System (ADS)

Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.

2017-04-01

The hydrogen bonded molecular complex bis(1-hydroxy-2-methylpropan-2-aminium)selenate (C8H24N2O6Se) has been prepared by the reaction of 2-amino-2-methyl propanol and selenic acid. The X-ray diffraction analysis revealed that the intermolecular proton transfer from selenic acid (SeO4H2) to 2-amino-2-methylpropanol results in the formation of bis(1-hydroxy-2-methylpropan-2-aminium)selenate (HMPAS) salt and the fragments are connected through H-bonding and ion pairing. The N-H⋯O and O-H⋯O interactions between 2-amino-2-methylpropanol and selenic acid determine the supramolecular arrangement in three-dimensional space. The salt crystallises in the space group P121/n1 of monoclinic system. The complete vibrational assignments of HMPAS have been performed by FTIR and FT-Raman spectroscopy. The experimental data are correlated with the structural properties namely the energy, thermodynamic parameters, atomic charges, hybridization concepts and vibrational frequencies determined by quantum chemical studies performed with B3LYP method using 6-311++G*, 6-31+G* and 6-31G** basis sets.

Identification and Characterization of Bacteria in a Selenium-Contaminated Hypersaline Evaporation Pond

PubMed Central

de Souza, M. P.; Amini, A.; Dojka, M. A.; Pickering, I. J.; Dawson, S. C.; Pace, N. R.; Terry, N.

2001-01-01

Solar evaporation ponds are commonly used to reduce the volume of seleniferous agricultural drainage water in the San Joaquin Valley, Calif. These hypersaline ponds pose an environmental health hazard because they are heavily contaminated with selenium (Se), mainly in the form of selenate. Se in the ponds may be removed by microbial Se volatilization, a bioremediation process whereby toxic, bioavailable selenate is converted to relatively nontoxic dimethylselenide gas. In order to identify microbes that may be used for Se bioremediation, a 16S ribosomal DNA phylogenetic analysis of an aerobic hypersaline pond in the San Joaquin Valley showed that a previously unaffiliated group of uncultured bacteria (belonging to the order Cytophagales) was dominant, followed by a group of cultured γ-Proteobacteria which was closely related to Halomonas species. Se K-edge X-ray absorption spectroscopy of selenate-treated bacterial isolates showed that they accumulated a mixture of predominantly selenate and a selenomethionine-like species, consistent with the idea that selenate was assimilated via the S assimilation pathway. One of these bacterial isolates (Halomonas-like strain MPD-51) was the best candidate for the bioremediation of hypersaline evaporation ponds contaminated with high Se concentrations because it tolerated 2 M selenate and 32.5% NaCl, grew rapidly in media containing selenate, and accumulated and volatilized Se at high rates (1.65 μg of Se g of protein−1 h−1), compared to other cultured bacterial isolates. PMID:11525968

Effects of selenizing angelica polysaccharide and selenizing garlic polysaccharide on immune function of murine peritoneal macrophage.

PubMed

Gao, Zhenzhen; Liu, Kuanhui; Tian, Weijun; Wang, Hongchao; Liu, Zhenguang; Li, Youying; Li, Entao; Liu, Cui; Li, Xiuping; Hou, Ranran; Yue, Chanjuan; Wang, Deyun; Hu, Yuanliang

2015-07-01

The effects of two selenizing polysaccharides (sCAP2 and sGPS6) on immune function of murine peritoneal macrophages taking two non-selenizing polysaccharides (CAP and GPS) and modifier Na2SeO3 as control. In vitro test, the changes of selenizing polysaccharides, non-selenizing polysaccharides and Na2SeO3 on murine macrophages function were evaluated by phagocytosis and nitric oxide (NO) secretion tests. In vivo test, the mice were injected respectively with 0.2, 0.4 and 0.6 mg of sCAP2, sGPS6, CAP and GPS, or Na2SeO3 80 μg or normal saline 0.4 mL. The peritoneal macrophages were collected and cultured to determine the contents of TNF-α, IL-6 and IL-10 in supernatants by enzyme-linked immunosorbent assay. The results showed that sCAP2 and sGPS6 could significantly promote the phagocytosis and secretion of NO and three cytokines of macrophages in comparison with CAP and GPS. sCAP2 possessed the strongest activity. This indicates that selenylation modification can further improve the immune-enhancing activity of polysaccharide, and sCAP2 could be as a new immunopotentiator. Copyright © 2015 Elsevier B.V. All rights reserved.

Changes in SeMSC, glucosinolates and sulforaphane levels, and in proteome profile in broccoli (Brassica oleracea var. Italica) fertilized with sodium selenate.

PubMed

Sepúlveda, Ignacio; Barrientos, Herna; Mahn, Andrea; Moenne, Alejandra

2013-05-07

The aim of this work was to analyze the effect of sodium selenate fortification on the content of selenomethyl selenocysteine (SeMSC), total glucosinolates and sulforaphane, as well as the changes in protein profile of the inflorescences of broccoli (Brassica oleracea var. Italica). Two experimental groups were considered: plants treated with 100 μmol/L sodium selenate (final concentration in the pot) and control plants treated with water. Fortification began 2 weeks after transplantation and was repeated once a week during 10 weeks. Broccoli florets were harvested when they reached appropriate size. SeMSC content in broccoli florets increased significantly with sodium selenate fortification; but total glucosinolates and sulforaphane content as well as myrosinase activity were not affected. The protein profile of broccoli florets changed due to fortification with sodium selenate. Some proteins involved in general stress-responses were up-regulated, whereas down-regulated proteins were identified as proteins involved in protection against pathogens. This is the first attempt to evaluate the physiological effect of fortification with sodium selenate on broccoli at protein level. The results of this work will contribute to better understanding the metabolic processes related with selenium uptake and accumulation in broccoli.

CZTSe solar cells prepared by electrodeposition of Cu/Sn/Zn stack layer followed by selenization at low Se pressure

PubMed Central

2014-01-01

Cu2ZnSnSe4 (CZTSe) thin films are prepared by the electrodeposition of stack copper/tin/zinc (Cu/Sn/Zn) precursors, followed by selenization with a tin source at a substrate temperature of 530°C. Three selenization processes were performed herein to study the effects of the source of tin on the quality of CZTSe thin films that are formed at low Se pressure. Much elemental Sn is lost from CZTSe thin films during selenization without a source of tin. The loss of Sn from CZTSe thin films in selenization was suppressed herein using a tin source at 400°C (A2) or 530°C (A3). A copper-poor and zinc-rich CZTSe absorber layer with Cu/Sn, Zn/Sn, Cu/(Zn + Sn), and Zn/(Cu + Zn + Sn) with metallic element ratios of 1.86, 1.24, 0.83, and 0.3, respectively, was obtained in a selenization with a tin source at 530°C. The crystallized CZTSe thin film exhibited an increasingly (112)-preferred orientation at higher tin selenide (SnSe x ) partial pressure. The lack of any obvious Mo-Se phase-related diffraction peaks in the X-ray diffraction (XRD) diffraction patterns may have arisen from the low Se pressure in the selenization processes. The scanning electron microscope (SEM) images reveal a compact surface morphology and a moderate grain size. CZTSe solar cells with an efficiency of 4.81% were produced by the low-cost fabrication process that is elucidated herein. PMID:25593559

Simultaneous reduction of nitrate and selenate by cell suspensions of selenium-respiring bacteria

USGS Publications Warehouse

Oremland, R.S.; Blum, J.S.; Bindi, A.B.; Dowdle, P.R.; Herbel, M.; Stolz, J.F.

1999-01-01

Washed-cell suspensions of Sulfurospirillum barnesii reduced selenate [Se(VI)] when cells were cultured with nitrate, thiosulfate, arsenate, or fumarate as the electron acceptor. When the concentration of the electron donor was limiting, Se(VI) reduction in whole cells was approximately fourfold greater in Se(VI)-grown cells than was observed in nitrate-grown cells; correspondingly, nitrate reduction was ~11-fold higher in nitrate-grown cells than in Se(VI)-grown cells. However, a simultaneous reduction of nitrate and Se(VI) was observed in both cases. At nonlimiting electron donor concentrations, nitrate- grown cells suspended with equimolar nitrate and selenate achieved a complete reductive removal of nitrogen and selenium oxyanions, with the bulk of nitrate reduction preceding that of selenate reduction. Chloramphenicol did not inhibit these reductions. The Se(VI)-respiring haloalkaliphile Bacillus arsenicoselenatis gave similar results, but its Se(VI) reductase was not constitutive in nitrate-grown cells. No reduction of Se(VI) was noted for Bacillus selenitireducens, which respires selenite. The results of kinetic experiments with cell membrane preparations of S. barnesii suggest the presence of constitutive selenate and nitrate reduction, as well as an inducible, high- affinity nitrate reductase in nitrate-grown cells which also has a low affinity for selenate. The simultaneous reduction of micromolar Se(VI) in the presence of millimolar nitrate indicates that these organisms may have a functional use in bioremediating nitrate-rich, seleniferous agricultural wastewaters. Results with 75Se-selenate tracer show that these organisms can lower ambient Se(VI) concentrations to levels in compliance with new regulations proposed for release of selenium oxyanions into the environment.

Genetic Identification of an Enzymatic Se(VI) Reduction Pathway

NASA Astrophysics Data System (ADS)

Yee, N.; Kobayashi, D. Y.

2006-12-01

Enterobacter cloacae is a biofilm-forming organism that colonizes the subterranean portions of plants. Because of its ability to catalyze the reduction of selenium oxyanions, this bacterium plays an important role in Se(0) biomineralization and Se cycling in soils. Identification of the genes that regulate selenate reductase activity is needed to elucidate the mechanisms employed by this organism to reduce Se(VI). However, the genes in E. cloacae involved in selenium reduction are currently unknown. In this study, transposon mutagenesis and direct cloning techniques were used to identify genetic regions in E. cloacae SLD1a-1 associated with selenate reductase activity. The mini-Tn5 transposon system was used to produce mutants that have lost the ability to reduce selenate. E. cloacae mutants and genomic library clones heterologously expressed in E. coli S17-1 were screened for activity on LB agar supplemented with sodium selenate. The rate of selenate reduction by the clones was measured in liquid minimal media, and the Se(0) minerals formed by the clones were examined using EXAFS, TEM, and XRD. The transposon mutagenesis experiments revealed that mutation of menaquinone biosynthesis genes inhibits selenate reduction. The direct cloning experiments showed that heterologous expression of the global anaerobic regulatory gene fnr from Enterobacter cloacae in the non Se-reducing strain E. coli S17-1 activated selenate reductase activity and the ability to precipitate Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at similar rates as E. cloacae and produced elemental selenium particles with identical morphologies and short range atomic order. These findings indicate that Se(VI) reduction by facultative anaerobes is regulated by anaerobic electron carriers and oxygen sensing transcription factors.

Influencing Mechanism of the Selenization Temperature and Time on the Power Conversion Efficiency of Cu2ZnSn(S,Se)4-Based Solar Cells.

PubMed

Xiao, Zhen-Yu; Yao, Bin; Li, Yong-Feng; Ding, Zhan-Hui; Gao, Zhong-Min; Zhao, Hai-Feng; Zhang, Li-Gong; Zhang, Zhen-Zhong; Sui, Ying-Rui; Wang, Gang

2016-07-13

Cu2ZnSn(S,Se)4 (CZTSSe) films were deposited on the Mo-coated glass substrates, and the CZTSSe-based solar cells were successfully fabricated by a facile solution method and postselenization technique. The influencing mechanisms of the selenization temperature and time on the power conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) of the solar cell are systematically investigated by studying the change of the shunt conductance (Gsh), series resistance (Rs), diode ideal factor (n), and reversion saturation current density (J0) with structure and crystal quality of the CZTSSe film and CZTSSe/Mo interface selenized at various temperatures and times. It is found that a Mo(S1-x,Sex)2 (MSSe) layer with hexagonal structure exists at the CZTSSe/Mo interface at the temperature of 500 °C, and its thickness increases with increasing selenization temperature and time. The MSSe has a smaller effect on the Rs, but it has a larger influence on the Gsh, n, and J0. The PCE, Voc, and FF change dominantly with Gsh, n, and J0, while Jsc changes with Rs and Gsh, but not Rs. These results suggest that the effect of the selenization temperature and time on the PCE is dominantly contributed to the change of the CZTSSe/CdS p-n junction and CZTSSe/MSSe interface induced by variation of the quality of the CZTSSe film and thickness of MSSe in the selenization process. By optimizing the selenization temperature and time, the highest PCE of 7.48% is obtained.

Launch of the SELENE(Kaguya) Mission and their Science Goals

NASA Astrophysics Data System (ADS)

Kato, M.; Takizawa, Y.; Sasaki, S.

2007-12-01

Implementation of Lunar orbiting satellite SELENE(Kaguya) has completed after final integration tests of thermal- vacuum and electromagnetic compatibility in the end of February 2007. Through pre-shipping reviews the satellite was carried to JAXA Tanegashima Space Center. The SELENE(Kaguya) is just being launched in September 2007. The mission has started in 1999 FY as a joint project of ISAS and NASDA, which have been merged into a space agency JAXA in October 2003. The SELENE certainly identified as a JAXA's science mission is operated from the newly installed SOAC (SELENE Operation and data Analysis Center) of Sagamihara/JAXA. The SELENE will be inserted into lunar orbit three weeks after launch using phasing orbit turning around Earth-Moon system. The main satellite will settle into a circular polar orbit with 100km altitude after releasing two sub-satellites in about 40 days after launch. After deploying magnetometer mast and a pair of sounder antenna, initial checks of scientific instruments will be carried for two months. Key questions on lunar science are "gWhat's origin of the Moon?"h, "gHow does the Moon have evolved?"h, and "gWhat history does the lunar environment have passed?"h Science topics to be studied by using fourteen science instruments are surface composition of chemistry and mineralogy, evolution tectonics of surface including subsurface to 5 km depth, gravity field of whole moon and magnetic field distribution for the study on origin and evolution of the Moon. Lunar environment are investigated in observing charged and neutral particles impinged on the surface. High definition TV cameras are also onboard the SELENE for public outreach.

Global Lunar Gravity Field Recovery from SELENE

NASA Technical Reports Server (NTRS)

Matsumoto, Koji; Heki, Kosuke; Hanada, Hideo

2002-01-01

Results of numerical simulation are presented to examine the global gravity field recovery capability of the Japanese lunar exploration project SELENE (Selenological and Engineering Explorer) which will be launched in 2005. New characteristics of the SELENE lunar gravimetry include four-way satellite-to-satellite Doppler tracking of main orbiter and differential VLBI tracking of two small free-flier satellites. It is shown that planned satellites configuration will improve lunar gravity field in wide range of wavelength as well as far-side selenoid.

Orbit Determination of the SELENE Satellites Using Multi-Satellite Data Types and Evaluation of SELENE Gravity Field Models

NASA Technical Reports Server (NTRS)

Goossens, S.; Matsumoto, K.; Noda, H.; Araki, H.; Rowlands, D. D.; Lemoine, F. G.

2011-01-01

The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis. It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an average level of 18m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the SELENE models, depending on whether l-day data overlaps or I-day predictions are used.

Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: biogeochemical significance of a novel, sulfate-independent respiration

USGS Publications Warehouse

Oremland, Ronald S.; Hollibaugh, James T.; Maest, Ann S.; Presser, Theresa S.; Miller, Laurence G.; Culbertson, Charles W.

1989-01-01

Interstitial water profiles of SeO42−, SeO32−, SO42−, and Cl− in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO42− occurred under anaerobic conditions, was more rapid with H2 or acetate, and was inhibited by O2, NO3−, MnO2, or autoclaving but not by SO42− or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO2. A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.

Identification of anaerobic selenate-respiring bacteria from aquatic sediments.

PubMed

Narasingarao, Priya; Häggblom, Max M

2007-06-01

The diversity population of microorganisms with the capability to use selenate as a terminal electron acceptor, reducing it to selenite and elemental selenium by the process known as dissimilatory selenate reduction, is largely unknown. The overall objective of this study was to gain an in-depth understanding of anaerobic biotransformation of selenium in the environment, particularly anaerobic respiration, and to characterize the microorganisms catalyzing this process. Here, we demonstrate the isolation and characterization of four novel anaerobic dissimilatory selenate-respiring bacteria enriched from a variety of sources, including sediments from three different water bodies in Chennai, India, and a tidal estuary in New Jersey. Strains S5 and S7 from India, strain KM from the Meadowlands, NJ, and strain pn1, categorized as a laboratory contaminant, were all phylogenetically distinct, belonging to various phyla in the bacterial domain. The 16S rRNA gene sequence shows that strain S5 constitutes a new genus belonging to Chrysiogenetes, while strain S7 belongs to the Deferribacteres, with greater than 98% 16S rRNA gene similarity to Geovibrio ferrireducens. Strain KM is related to Malonomonas rubra, Pelobacter acidigallici, and Desulfuromusa spp., with 96 to 97% 16S rRNA gene similarity. Strain pn1 is 99% similar to Pseudomonas stutzeri. Strains S5, S7, and KM are obligately anaerobic selenate-respiring microorganisms, while strain pn1 is facultatively anaerobic. Besides respiring selenate, all these strains also respire nitrate.

Effect of Sodium Selenate on Hippocampal Proteome of 3×Tg-AD Mice-Exploring the Antioxidant Dogma of Selenium against Alzheimer's Disease.

PubMed

Iqbal, Javed; Zhang, Kaoyuan; Jin, Na; Zhao, Yuxi; Liu, Qiong; Ni, Jiazuan; Shen, Liming

2018-04-19

Selenium (Se), an antioxidant trace element, is an important nutrient for maintaining brain functions and is reported to be involved in Alzheimer's disease (AD) pathologies. The present study has been designed to elucidate the protein changes in hippocampus of 3×Tg-AD mice after supplementing sodium selenate as an inorganic source of selenium. By using iTRAQ proteomics technology, 113 differentially expressed proteins (DEPs) are found in AD/WT mice with 37 upregulated and 76 downregulated proteins. Similarly, in selenate-treated 3×Tg-AD (ADSe/AD) mice, 115 DEPs are found with 98 upregulated and 17 downregulated proteins. The third group of mice (ADSe/WT) showed 75 DEPs with 46 upregulated and 29 downregulated proteins. Among these results, 42 proteins (40 downregulated and 2 upregulated) in the diseased group showed reverse expression when treated with selenate. These DEPs are analyzed with different bioinformatics tools and are found associated with various AD pathologies and pathways. Based on their functions, selenate-reversed proteins are classified as structural proteins, metabolic proteins, calcium regulating proteins, synaptic proteins, signaling proteins, stress related proteins, and transport proteins. Six altered AD associated proteins are successfully validated by Western blot analysis. This study shows that sodium selenate has a profound effect on the hippocampus of the triple transgenic AD mice. This might be established as an effective therapeutic agent after further investigation.

Selenization of CIS and CIGS layers deposited by chemical spray pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, B. J.; Egaas, B.; Velumani, S.

Cu(In1-xGax)Se2 (CIGS) thin films with x=0 (CIS) and x=0.3 (CIGS) were prepared on Mo-coated glass substrate by using chemical spray pyrolysis at a substrate temperature of 350 degrees C, followed by selenization treatment at 550 degrees C in selenium environment under N2 gas flow. X-ray diffraction patterns of as-deposited CIGS layers on Mo showed polycrystalline chalcopyrite phase with an intense (112) plane. Splitting of (204)/(220) and (116)/(312) planes for the film with x=0.3 reveals deviation of tetragonal nature. Field emission scanning electron microscopy cross-sectional images of selenized films showed clear re-crystallization of grains. During the selenization process of the CIGSmore » absorber, a thin interface layer of MoSe2 is formed. Line mapping of Mo/CIGS layer showed more gallium segregation at the interface of back contact resulting in band gap grading. Chemical composition and mapping of the as-deposited and selenized samples were determined by energy dispersive analysis of X-rays. This work leads to fabrication of low cost and large scale Mo/CIGS/CdS/ZnO/ZnO:Al device structure.« less

Variations in the accumulation, localization and rate of metabolization of selenium in mature Zea mays plants supplied with selenite or selenate.

PubMed

Longchamp, Mélanie; Castrec-Rouelle, Maryse; Biron, Philippe; Bariac, Thierry

2015-09-01

Quantification of selenium bioavailability from foods is a key challenge following the discovery of the antioxidant role of this micronutrient in human health. This study presents the uptake, accumulation and rate of metabolization in mature Zea mays plants grown in hydroponic solution supplemented with selenate or selenite. Selenium content was lower in plants supplemented with selenate and accumulated mainly in the leaves compared with selenite-treated plants where the selenium was retained in the roots. Selenite-treated grains accumulated more selenium. Selenate was metabolized less than selenite in whole plants, but in grains selenium was present exclusively as organic selenium compounds. For humans, the bioavailability of organic selenium was evaluated at 90% compared with only 50% for inorganic forms. Our results show that the potential for selenium bioavailability is increased with selenite treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adsorption mechanisms of selenium oxyanions at the aluminum oxide/water interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peak, Derek

2008-06-09

Sorption processes at the mineral/water interface typically control the mobility and bioaccessibility of many inorganic contaminants such as oxyanions. Selenium is an important micronutrient for human and animal health, but at elevated concentrations selenium toxicity is a concern. The objective of this study was to determine the bonding mechanisms of selenate (SeO{sub 4}{sup 2-}) and selenite (SeO{sub 3}{sup 2-}) on hydrous aluminum oxide (HAO) over a wide range of reaction pH using extended X-ray absorption fine structure (EXAFS) spectroscopy. Additionally, selenate adsorption on corundum ({alpha}-Al{sub 2}O{sub 3}) was studied to determine if adsorption mechanisms change as the aluminum oxide surfacemore » structure changes. The overall findings were that selenite forms a mixture of outer-sphere and inner-sphere bidentate-binuclear (corner-sharing) surface complexes on HAO, selenate forms primarily outer-sphere surface complexes on HAO, and on corundum selenate forms outer-sphere surface complexes at pH 3.5 but inner-sphere monodentate surface complexes at pH 4.5 and above. It is possible that the lack of inner-sphere complex formation at pH 3.5 is caused by changes in the corundum surface at low pH or secondary precipitate formation. The results are consistent with a structure-based reactivity for metal oxides, wherein hydrous metal oxides form outer-sphere complexes with sulfate and selenate, but inner-sphere monodentate surface complexes are formed between sulfate and selenate and {alpha}-Me{sub 2}O{sub 3}.« less

Organic Selenium, Selenate and Selenite Accumulation by Lake Plankton and the Alga Chlamydomonas reinhardtii at Different pH and Sulfate Concentrations.

PubMed

Ponton, Dominic E; Fortin, Claude; Hare, Landis

2018-04-19

Selenium (Se) concentrations measured in lake planktonic food chains (microplankton < 64 µm, copepods and Chaoborus larvae) were strongly correlated with the concentrations of dissolved organic Se. These correlations were strengthened slightly by adding the concentrations of dissolved selenate to those of organic Se. To better understand the role of Se species and the influence of water chemistry on Se uptake, we exposed the green alga Chlamydomonas reinhardtii to selenite, selenate or selenomethionine at various H + ion and sulfate concentrations under controlled laboratory conditions. At low sulfate concentrations, inorganic Se species (selenate > selenite) were more readily accumulated by this alga than was selenomethionine. However, at higher sulfate concentrations the uptake of selenite was higher than that of selenate while the uptake of selenomethionine remained unchanged. While pH of the exposure water did not influence the uptake of selenate by this alga, the accumulation of selenomethionine and selenite increased with pH because of their relative pH-related speciation. The Se concentrations that we measured in C. reinhardtii exposed to selenomethionine were 30 times lower than those that we measured in field-collected microplankton exposed in the same laboratory conditions. This difference is explained by the taxa present in the microplankton samples. Using our laboratory measurements of Se uptake in microplankton and our natural Se concentrations in lakewater allowed us to model Se concentrations in a lake pelagic food chain. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids.

PubMed

Schiavon, Michela; Berto, Chiara; Malagoli, Mario; Trentin, Annarita; Sambo, Paolo; Dall'Acqua, Stefano; Pilon-Smits, Elizabeth A H

2016-01-01

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2-3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20-30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7-15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5-10 μM selenate supply in hydroponics. The radishes metabolized selenate to the anticarcinogenic compound Se-methyl-selenocysteine. Selenate treatment enhanced levels of other nutraceuticals in radish roots, including glucoraphanin. Therefore, Se biofortification can produce plants with superior health benefits.

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids

PubMed Central

Schiavon, Michela; Berto, Chiara; Malagoli, Mario; Trentin, Annarita; Sambo, Paolo; Dall'Acqua, Stefano; Pilon-Smits, Elizabeth A. H.

2016-01-01

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2–3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20–30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7–15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5–10 μM selenate supply in hydroponics. The radishes metabolized selenate to the anticarcinogenic compound Se-methyl-selenocysteine. Selenate treatment enhanced levels of other nutraceuticals in radish roots, including glucoraphanin. Therefore, Se biofortification can produce plants with superior health benefits. PMID:27683583

Hazard assessment of inorganics to three endangered fish in the Green River, Utah

USGS Publications Warehouse

Hamilton, S.J.

1995-01-01

Acute toxicity tests were conducted with three life stages of Colorado squawfish (Ptychocheilus lucius), razorback sucker (Xyrauchen texanus), and bonytail (Gila elegans) in a reconstituted water quality simulating the middle part of the Green River of Utah. Tests were conducted with boron, lithium, selenate, selenite, uranium, vanadium, and zinc. The overall rank order of toxicity to all species and life stages combined from most to least toxic was vanadium = zinc > selenite > lithium = uranium > selenate > boron. There was no difference between the three species in their sensitivity to the seven inorganics based on a rank-order evaluation at the species level. Colorado squawfish were 2-5 times more sensitive to selenate and selenite at the swimup life stage than older stages, whereas razorback suckers displayed equal sensitivity among life stages. Bonytail exhibited equal sensitivity to selenite, but were five times more sensitive to selenate at the swimup life stage than the older stages. Comparison of 96-hr LC50 values with a limited number of environmental water concentrations in Ashley Creek, Utah, which receives irrigation drainwater, revealed moderate hazard ratios for boron, selenate, selenite, and zinc, low hazard ratios for uranium and vanadium, but unknown ratios for lithium. These inorganic contaminants in drainwaters may adversely affect endangered fish in the Green River.

Respiration of arsenate and selenate by hyperthermophilic archaea.

PubMed

Huber, R; Sacher, M; Vollmann, A; Huber, H; Rose, D

2000-10-01

A novel, strictly anaerobic, hyperthermophilic, facultative organotrophic archaeon was isolated from a hot spring at Pisciarelli Solfatara, Naples, Italy. The rod-shaped cells grew chemolithoautotrophically with carbon dioxide as carbon source, hydrogen as electron donor and arsenate, thiosulfate or elemental sulfur as electron acceptor. H2S was formed from sulfur or thiosulfate, arsenite from arsenate. Organotrophically, the new isolate grew optimally in the presence of an inorganic electron acceptor like sulfur, selenate or arsenate. Cultures, grown on arsenate and thiosulfate or arsenate and L-cysteine, precipitated realgar (As2S2). During growth on selenate, elemental selenium was produced. The G+C content of the DNA was 58.3 mol%. Due to 16S rRNA gene sequence analysis combined with physiological and morphological criteria, the new isolate belongs to the Thermoproteales order. It represents a new species within the genus Pyrobaculum, the type species of which we name Pyrobaculum arsenaticum (type strain PZ6*, DSM 13514, ATCC 700994). Comparative studies with different Pyrobaculum-species showed, that Pyrobaculum aerophilum was also able to grow organotrophically under anaerobic culture conditions in the presence of arsenate, selenate and selenite. During growth on selenite, elemental selenium was formed as final product. In contrast to P. arsenaticum, P. aerophilum could use selenate or arsenate for lithoautotrophic growth with carbon dioxide and hydrogen.

Effect of Selenization Processes on CIGS Solar Cell Performance.

PubMed

Wu, C H; Wu, P W; Chen, J H; Kao, J Y; Hsu, C Y

2018-07-01

Cu(In, Ga)Se2 (CIGS) films were fabricated by a two-step process method using sputtering from Cu0.7Ga0.3 and In targets. The metallic precursor structures of In/CuGa/In were prepared, and CuGa film was adjusted to the thicknesses of 150, 200, 250 and 300 nm, in order to optimize the CIGS film. After selenization, three independent CIGS (112), CIGS (220/204) and CIGS (312/116) began to crystallize at ~280 °C and phase peaks continued growing until 560 °C. Experimental results showed that with a single stage selenization method, the excessive stoichiometry of the CIGS films was obtained. Using three sequential stages for the selenization process, with a annealing time of 20 min, the stoichiometry of the CIGS absorbers with the Cu/(In + Ga) and Ga/(In + Ga) showed atomic ratios of 0.94 and 0.34, respectively. The intensity of the (112) XRD diffraction peak became stronger, indicating an improvement in the crystallinity. Raman spectra of CIGS absorbers showed a main peak (174 cm-1) and two weak signals (212 and 231 cm-1). TEM image for electron diffraction pattern showed that the grains were randomly oriented. CIGS solar cell device prepared with a proper selenization, a maximum efficiency of 12.45% was obtained.

Studies Based on Lunar Global Subsurface Radar Sounding Data Obtained by SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Haruyama, J.; Miyamoto, H.; Nishibori, T.; Tsuchiya, F.; Ohtake, M.

2018-04-01

Several studies based on lunar global subsurface radar sounding data obtained by SELENE/LRS will be reviewed. From the subsurface structures of the buried regolith layers, we can discuss the evolution of tectonic and volcanic processes in the maria.

Novel in situ resistance measurement for the investigation of CIGS growth in a selenization process

NASA Astrophysics Data System (ADS)

Liu, Wei; Tian, Jian-Guo; Li, Zu-Bin; He, Qing; Li, Feng-Yan; Li, Chang-Jian; Sun, Yun

2009-03-01

During the selenization process of CIGS thin films, the relation between the element loss rate and the precursor depositions are analyzed. The growth of the CIGS thin films during the selenization process is investigated by the novel in situ resistance measurement, by which the formation of compound semiconductors can be observed directly and simultaneously. Their structures, phase evolutions and element losses are analyzed by XRD and XRF. Based on the experimental results, it can be concluded that the phase transforms have nothing to do with the deposition sequences of precursors, while the element loss rates are related to the deposition sequences in this process. In addition, element loss mechanisms of CIGS thin films prepared by the selenization process are analyzed by the phase evolutions and chemical combined path in the In, Ga-Se reaction processes. Moreover it is verified that the element losses are depressed by increasing the ramping-up rate finally. The results provide effective methods to fabricate high-quality CIGS thin films with low element losses.

Theoretical crystal chemistry of M{sub x}(TO{sub 4}){sub y} sulfates and selenates: Topological analysis and classification of suprapolyhedral invariants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilyushin, G. D.; Blatov, V. A.

2006-05-15

A geometric topological analysis of orthotetrahedral phases M{sub x}(TO{sub 4}){sub y} (T = S or Se) is performed for 46 sulfates and 17 selenates with the TOPOS 3.2 software package. The values of coordination sequences {l_brace}N{sub k}{r_brace} of T atoms are used as classification parameters of topologically different MTO nets. The crystal structures are analyzed within 12 coordination spheres of T sites and assigned to 26 topological types. It is established that only 7 types are common for the structures of sulfates and selenates, 16 types include only sulfates, and 3 types include only selenates. The average values of themore » bond lengths are determined: = 1.48(2) A and = 1.63(2) A. The hierarchical ordering of the crystal structure is performed using the concept of a polyhedral microensemble of the structure.« less

Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

PubMed Central

Nishinaga, Osamu; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2013-01-01

Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing. PMID:24067318

Differential effects of selenite and selenate on human melanocytes, keratinocytes, and melanoma cells.

PubMed

Bandura, Laura; Drukala, Justyna; Wolnicka-Glubisz, Agnieszka; Björnstedt, Mikael; Korohoda, Wlodzimierz

2005-04-01

Among the substances that attracted the attention of oncologists in recent years are selenium-containing compounds, both inorganic and organic. Several epidemiological studies have shown an inverse correlation between selenium intake and cancer incidence. In the experiments reported here, we compared the effects of 2 inorganic selenium-containing salts that differed in the level of selenium oxidation, selenite IV and selenate VI. We tested the effects of these 2 compounds on cell survival and growth, cell cycle processing, cell morphology, cytoskeleton, and lipid peroxidation in 3 human skin cell types: normal keratinocytes, melanocytes, and human melanoma cell line HTB140. The different effects of selenite and selenate on the viability, growth, and morphology of normal cells and tumor cells are reported and provide a base for future research and treatment of some neoplastic diseases. The attention is paid to cell apoptosis induced by selenite and not by selenate, and the effects of tested substances on thioredoxin reductase system are postulated.

Global Lunar Gravity Field Determination Using Historical and Recent Tracking Data in Preparation for SELENE

NASA Astrophysics Data System (ADS)

Goossens, S.; Matsumoto, K.; Namiki, N.; Hanada, H.; Iwata, T.; Tsuruta, S.; Kawano, N.; Sasaki, S.

2006-12-01

In the near future, a number of satellite missions are planned to be launched to the Moon. These missions include initiatives by China, India, the USA, as well as the Japanese SELENE mission. These missions will gather a wealth of lunar data which will improve the knowledge of the Moon. One of the main topics to be addressed will be the lunar gravity field. Especially SELENE will contribute to improving the knowledge of the gravity field, by applying 4-way Doppler tracking between the main satellite and a relay satellite, and by applying a separate differential VLBI experiment. These will improve the determination of the global gravity field, especially over the far side and at the lower degrees (mostly for degrees lower than 30), as is shown by extensive simulations of the SELENE mission. This work focuses on the determination of the global lunar gravity field from all available tracking data to this date. In preparation for the SELENE mission, analysis using Lunar Prospector tracking data, as well as Clementine data and historical data from the Apollo and Lunar Orbiter projects is being conducted at NAOJ. Some SMART-1 tracking data are also included. The goal is to combine the good-quality data from the existing lunar missions up to this date with the tracking data from SELENE in order to derive a new lunar gravity field model. The focus therefore currently lies on processing the available data and extracting lunar gravity field information from them. It is shown that the historical tracking data contribute especially to the lower degrees of the global lunar gravity field model. Due to the large gap in tracking data coverage over the far side for the historical data, the higher degrees are almost fully determined by the a priori information in the form of a Kaula rule. The combination with SELENE data is thus expected to improve the estimate for the lower degrees even further, including coverage of the far side. Since historical tracking data are from orbits with different inclinations, this helps to break several correlations and assures better orbit predictions for those inclinations included, although the current models are still tuned heavily towards the polar orbit. Covariance analysis using the covariance of current solutions as well as the covariance from SELENE simulations also shows further improvement to be expected from the combination of the data sets. The expected improvement in the determination of the lower degrees also leads to an expectation of deriving stricter limits on the lunar k_2 Love number.

Detection of over 100 selenium metabolites in selenized yeast by liquid chromatography electrospray time-of-flight mass spectrometry.

PubMed

Gilbert-López, Bienvenida; Dernovics, Mihaly; Moreno-González, David; Molina-Díaz, Antonio; García-Reyes, Juan F

2017-08-15

The characterization of the selenometabolome of Selenized(Se)-yeast, that is the fraction of water soluble low-molecular weight Se-metabolites produced in Se-yeast is of paramount interest to expand the knowledge on the composition of this food supplement. In this work, we have applied liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) to search for Se-species from the low molecular weight range fraction of the selenized yeast used for food supplements. Prior to LC-TOFMS, sample treatment consisted of ultrasound assisted water extraction followed by size exclusion fractionation assisted with off-line inductively coupled plasma mass spectrometry detection of isotope 82 Se. The fraction corresponding to low-molecular weight species was subjected to LC-TOFMS using electrospray ionization in the positive ion mode. The detection of the suspected selenized species has been based on the information obtained from accurate mass measurements of both the protonated molecules and fragments from in-source CID fragmentation; along with the characteristic isotope pattern exhibited by the presence of Se. The approach enables the detection of 103 selenized species, most of them not previously reported, in the range from ca. 300-650Da. Besides the detection of selenium species, related sulphur derivate metabolites were detected based on the accurate mass shift due to the substitution of sulphur and selenium. Copyright © 2017. Published by Elsevier B.V.

ADSORPTION MECHANISMS AND TRANSPORT BEHAVIOR BETWEEN SELENATE AND SELENITE ON DIFFERENT SORBENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snyder, Michelle MV; Um, Wooyong

Adsorption of different oxidation species of selenium (Se), selenate (SeO42-) and selenite (SeO32-), with varying pHs (2 - 10) and ionic strengths (I = 0.01 M, 0.1 M and 1.0 M NaNO3) was measured on quartz, aluminum oxide, and synthetic iron oxide (ferrihydrite) using batch reactors to obtain a more detailed understanding of the adsorption mechanisms (e.g., inner- and outer-sphere complex). In addition to the batch experiments with single minerals contained in native Hanford Site sediment, additional batch adsorption studies were conducted with native Hanford Site sediment and groundwater as a function of 1) total Se concentration (from 0.01 tomore » 10 mg L-1) and 2) soil to solution ratios (1:20 and 1:2 grams per mL). Results from these batch studies were compared to a set of saturated column experiments that were conducted with natural Hanford sediment and groundwater spiked with either selenite or selenate to observe the transport behavior of these species. Both batch and column results indicated that selenite adsorption was consistently higher than that of selenate in all experimental conditions used. These different adsorption mechanisms between selenite and selenate result in the varying mobility of Se in the subsurface environment and explain the dependence on the oxidation species.« less

Macroscopic experimental and modeling evaluation of selenite and selenate adsorption mechanisms on gibbsite

USDA-ARS?s Scientific Manuscript database

Selenite Se(IV) and selenate Se(VI) selenium adsorption behavior was investigated on gibbsite as a function of solution pH and solution ionic strength. Adsorption of both Se redox states decreased with increasing solution pH. Electrophoretic mobility measurements showed downward shifts in point of...

Infrared spectroscopic study of SO₄²⁻ ions included in M'₂M''(SeO₄)₂⋅6H₂O (Me'=K, NH₄⁺; M''=Mg, Co, Ni, Cu, Zn) and NH₄⁺ ions included in K₂M(XO₄)₂⋅6H₂O (X=S, Se; M''=Mg, Co, Ni, Cu, Zn).

PubMed

Marinova, D; Karadjova, V; Stoilova, D

2015-01-05

Infrared spectra of Tutton compounds, M'₂M''(SeO₄)₂⋅6H₂O (M'=K, NH₄⁺; M''=Mg, Co, Ni, Cu, Zn; X=S, Se), as well as those of SO₄²⁻ guest ions included in selenate host lattices and of NH4(+) guest ions included in potassium host lattices are presented and discussed in the regions of ν₃ and ν₁ of SO₄²⁻ guest ions, ν₄ of NH₄⁺ guest ions and water librations. The SO₄²⁻ guest ions matrix-isolated in selenate matrices (approximately 2 mol%) exhibit three bands corresponding to ν₃ and one band corresponding to ν₁ in good agreement with the low site symmetry C₁ of the host selenate ions. When the larger SO₄²⁻ ions are replaced by the smaller SO₄²⁻ ions the mean values of the asymmetric stretching modes ν₃ of the included SO₄²⁻ ions are slightly shifted to lower frequencies as compared to those of the same ions in the neat sulfate compounds due to the smaller repulsion potential of the selenate matrices (larger unit-cell volumes of the selenates). It has been established that the extent of energetic distortion of the sulfate ions matrix-isolated in the ammonium selenates as deduced from the values of Δν₃ and Δν₃/νc is stronger than that of the same ions matrix-isolated in the potassium selenates due to the formation of hydrogen bonds between the SO₄²⁻ guest ions with both the water molecules in the host compounds and the NH₄⁺ host ions (for example, Δν₃ of the sulfate guest ions have values of 30 and 51 cm(-1) in the nickel potassium and ammonium compounds, and 33 and 49 cm(-1) in the zinc potassium and ammonium compounds, respectively). The infrared spectra of ammonium doped potassium sulfate matrices show three bands corresponding to Δν₄ of the included ammonium ions in agreement with the low site symmetry C₁ of the host potassium ions. However, the inclusion of ammonium ions in selenate matrices (with exception of the magnesium compound) leads to the appearance of four bands in the region of ν₄. At that stage of our knowledge we assume that some kind of disorder of the ammonium ions included in selenate lattices occurs due to the different proton acceptor capability of the SO₄²⁻ and SO₄²⁻ ions. The latter ions are known to exhibit stronger proton acceptor abilities. This fact will facilitate the formation of polyfurcate hydrogen bonds of the ammonium ions in the selenate matrices, thus leading to increasing in the coordination number of these ions, i.e. to a disorder of the ammonium guest ions. The strength of the hydrogen bonds formed in the title Tutton compounds as well as that of the hydrogen bonds in potassium compounds containing isomorphously included ammonium ions as deduced from the wavenumbers of the water librations are also discussed. The bands corresponding to water librations in the spectra of the mixed crystals K₁.₈(NH₄)₀.₂M(XO₄)₂⋅6H₂O (M=Mg, Co, Ni, Cu, Zn; X=S, Se) broaden and shift to lower frequencies as compared to those of the potassium host compounds, thus indicating that weaker hydrogen bonds are formed in the mixed crystals. These spectroscopic findings are owing to the decrease in the proton acceptor capacity of the SO₄²⁻ and SO₄²⁻ ions due to the formation of hydrogen bonds between the host anions and the guest ammonium cations additionally to water molecules (anti-cooperative or proton acceptor competitive effect). Furthermore, the band shifts in the spectra of the selenate matrices are generally larger than those observed in the spectra of the respective sulfates due to the stronger proton acceptor ability of the selenate ions. Copyright © 2014 Elsevier B.V. All rights reserved.

Infrared spectroscopic study of SO42- ions included in M‧2M‧‧(SeO4)2ṡ6H2O (Me‧ = K, NH4+; M‧‧ = Mg, Co, Ni, Cu, Zn) and NH4+ ions included in K2M(XO4)2ṡ6H2O (X = S, Se; M‧‧ = Mg, Co, Ni, Cu, Zn)

NASA Astrophysics Data System (ADS)

Marinova, D.; Karadjova, V.; Stoilova, D.

2015-01-01

Infrared spectra of Tutton compounds, M‧2M‧‧(XO4)2ṡ6H2O (M‧ = K, NH4+; M‧‧ = Mg, Co, Ni, Cu, Zn; X = S, Se), as well as those of SO42- guest ions included in selenate host lattices and of NH4+ guest ions included in potassium host lattices are presented and discussed in the regions of ν3 and ν1 of SO42- guest ions, ν4 of NH4+ guest ions and water librations. The SO42- guest ions matrix-isolated in selenate matrices (approximately 2 mol%) exhibit three bands corresponding to ν3 and one band corresponding to ν1 in good agreement with the low site symmetry C1 of the host selenate ions. When the larger SeO42- ions are replaced by the smaller SO42- ions the mean values of the asymmetric stretching modes νbar3 of the included SO42- ions are slightly shifted to lower frequencies as compared to those of the same ions in the neat sulfate compounds due to the smaller repulsion potential of the selenate matrices (larger unit-cell volumes of the selenates). It has been established that the extent of energetic distortion of the sulfate ions matrix-isolated in the ammonium selenates as deduced from the values of Δν3 and Δν3/νc is stronger than that of the same ions matrix-isolated in the potassium selenates due to the formation of hydrogen bonds between the SO42- guest ions with both the water molecules in the host compounds and the NH4+ host ions (for example, Δν3 of the sulfate guest ions have values of 30 and 51 cm-1 in the nickel potassium and ammonium compounds, and 33 and 49 cm-1 in the zinc potassium and ammonium compounds, respectively). The infrared spectra of ammonium doped potassium sulfate matrices show three bands corresponding to Δν4 of the included ammonium ions in agreement with the low site symmetry C1 of the host potassium ions. However, the inclusion of ammonium ions in selenate matrices (with exception of the magnesium compound) leads to the appearance of four bands in the region of ν4. At that stage of our knowledge we assume that some kind of disorder of the ammonium ions included in selenate lattices occurs due to the different proton acceptor capability of the SO42- and SeO42- ions. The latter ions are known to exhibit stronger proton acceptor abilities. This fact will facilitate the formation of polyfurcate hydrogen bonds of the ammonium ions in the selenate matrices, thus leading to increasing in the coordination number of these ions, i.e. to a disorder of the ammonium guest ions. The strength of the hydrogen bonds formed in the title Tutton compounds as well as that of the hydrogen bonds in potassium compounds containing isomorphously included ammonium ions as deduced from the wavenumbers of the water librations are also discussed. The bands corresponding to water librations in the spectra of the mixed crystals K1.8(NH4)0.2M(XO4)2ṡ6H2O (M = Mg, Co, Ni, Cu, Zn; X = S, Se) broaden and shift to lower frequencies as compared to those of the potassium host compounds, thus indicating that weaker hydrogen bonds are formed in the mixed crystals. These spectroscopic findings are owing to the decrease in the proton acceptor capacity of the SO42- and SeO42- ions due to the formation of hydrogen bonds between the host anions and the guest ammonium cations additionally to water molecules (anti-cooperative or proton acceptor competitive effect). Furthermore, the band shifts in the spectra of the selenate matrices are generally larger than those observed in the spectra of the respective sulfates due to the stronger proton acceptor ability of the selenate ions.

Preparation of Cu{sub 2}ZnSnSe{sub 4} solar cells by low-temperature co-evaporation and following selenization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Chao, E-mail: chao.gao@kit.edu; Hetterich, Michael; Schnabel, Thomas

2016-01-04

Cu{sub 2}ZnSnSe{sub 4} (CZTSe) thin films are prepared by a two-step method which involves co-evaporation of Cu, Zn, Sn, and Se on molybdenum-coated soda-lime glass at low substrate temperature and a following selenization. Solar cells with efficiencies of up to 6.5% can be achieved. The influence of the selenium deposition rates during co-evaporation and the nitrogen pressure during selenization on the properties of the CZTSe films are investigated. It is found that these two parameters can significantly affect the morphology and crystallinity of the CZTSe films. The possible reasons for the experimental results are discussed.

CyGaMEs Selene Player Log Dataset: Gameplay Assessment, Flow Dimensions and Non-Gameplay Assessments

ERIC Educational Resources Information Center

Reese, Debbie Denise

2015-01-01

The "Selene: A Lunar Construction GaME" instructional video game is a robust research environment (institutional review board approved) for investigating learning, affect, and the CyGaMEs Metaphorics approach to instructional video game design, embedded assessment, and informatics analysis and reporting. CyGaMEs applies analogical…

Macroscopic experimental and modeling evaluation of selenite and selenate adsorption mechanisms on gibbsite

USDA-ARS?s Scientific Manuscript database

Selenite Se(IV) and selenate Se(VI) adsorption behavior was investigated on gibbsite as a function of solution pH and solution ionic strength. Adsorption of both Se redox states decreased with increasing solution pH. Electrophoretic mobility measurements showed downward shifts in point of zero cha...

SELENE mission: mathematical model for SST Doppler measurements

NASA Astrophysics Data System (ADS)

Ping, J.; Kono, Y.; Kawano, N.; Hanada, H.; Matsumoto, K.

2001-09-01

Japanese lunar exploration mission, SELENE, has been planned to be launched into space by using H II-a rocket in the Summer of 2004. This mission is composed of 3 subsatellites, a main lunar orbiter, a relay satellite and a free flying VLBI radio source. One of its main scientific objectives is the estimation of high order and degree spherical harmonic coefficients for the lunar gravity field. Different tracking methods will be employed in SELENE. The key tracking method is 4 way Satellite-to-Satellite Tracking (SST) technique. By this way, the tracking data can be obtained through the relay when the low altitude main orbiter is flying at the far-side of the Moon and can not be "seen" from the Earth. To success the historical tracking data, a complete coverage of Doppler tracking from an orbiter at sufficiently low altitude with high tracking accuracy can be obtained. The 4 way SST has various configurations. For SELENE, the SST tracking mode is introduced here, the mathematical relation between range rate and 4 way Doppler count number is established, and a data processing stream frame by using GEODYN II is suggested.

Lunar Gravity Field Determination Using SELENE Same-Beam Differential VLBI Tracking Data

NASA Technical Reports Server (NTRS)

Goossens, S.; Matsumoto, K.; Liu, Q.; Kikuchi, F.; Sato, K.; Hanada, H.; Ishihara, Y.; Noda, H.; Kawano, N.; Namiki, N.;

Real-time observation of Cu2ZnSn(S,Se)4 solar cell absorber layer formation from nanoparticle precursors.

PubMed

Mainz, Roland; Walker, Bryce C; Schmidt, Sebastian S; Zander, Ole; Weber, Alfons; Rodriguez-Alvarez, Humberto; Just, Justus; Klaus, Manuela; Agrawal, Rakesh; Unold, Thomas

2013-11-07

The selenization of Cu-Zn-Sn-S nanocrystals is a promising route for the fabrication of low-cost thin film solar cells. However, the reaction pathway of this process is not completely understood. Here, the evolution of phase formation, grain size, and elemental distributions is investigated during the selenization of Cu-Zn-Sn-S nanoparticle precursor thin films by synchrotron-based in situ energy-dispersive X-ray diffraction and fluorescence analysis as well as by ex situ electron microscopy. The precursor films are heated in a closed volume inside a vacuum chamber in the presence of selenium vapor while diffraction and fluorescence signals are recorded. The presented results reveal that during the selenization the cations diffuse to the surface to form large grains on top of the nanoparticle layer and the selenization of the film takes place through two simultaneous reactions: (1) a direct and fast formation of large grained selenides, starting with copper selenide which is subsequently transformed into Cu2ZnSnSe4; and (2) a slower selenization of the remaining nanoparticles. As a consequence of the initial formation of copper selenides at the surface, the subsequent formation of CZTSe starts under Cu-rich conditions despite an overall Cu-poor composition of the film. The implications of this process path for the film quality are discussed. Additionally, the proposed growth model provides an explanation for the previously observed accumulation of carbon from the nanoparticle precursor beneath the large grained layer.

Impact of stacking order on the microstructural properties of Cu2ZnGeSe4 thin film absorber layer

NASA Astrophysics Data System (ADS)

Mary, G. Swapna; Chandra, G. Hema; Sunil, M. Anantha; Subbaiah, Y. P. Venkata; Gupta, Mukul; Rao, R. Prasada

2018-05-01

Six possible multiple stacks of Cu-ZnSe-Ge with selenium incorporation at a precursor stage were prepared using electron beam evaporation followed by vacuum selenization at 475 °C for 30 min to investigate the role of stacking order on the growth and properties of Cu2ZnGeSe4 films. The X-ray diffraction measurements affirm the existence of various binary and ternary phases (ZnSe, Cu2Se, GeSe2 and Cu2GeSe3) for all the precursor stacks. These phases are completely diminished after selenization at 475 °C except a minor co-existence of ZnSe (111) phase along with dominant Cu2ZnGeSe4 (112) phase for stack A: (Cu/Se/ZnSe/Se/Ge/Se) × 4. The Raman measurements for selenized multiple stack A, revealed two major A3, A1 modes at 206 cm-1 and 176 cm-1 and one minor E5 mode at 270 cm-1 corresponding to CZGSe phase. The surface morphology and the elemental distribution across the thickness found to vary significantly with the change of stacking order. The selenized multiple stacks A films shows densely packed flake and capsule shaped grains. The selenized stack A found to have a direct energy band gap of 1.60 eV, showing p-type conductivity with a Hall mobility of 22 cm2 (Vs)-1.

Selenium toxicity to honey bee (Apis mellifera L.) pollinators: effects on behaviors and survival.

PubMed

Hladun, Kristen R; Smith, Brian H; Mustard, Julie A; Morton, Ray R; Trumble, John T

2012-01-01

We know very little about how soil-borne pollutants such as selenium (Se) can impact pollinators, even though Se has contaminated soils and plants in areas where insect pollination can be critical to the functioning of both agricultural and natural ecosystems. Se can be biotransferred throughout the food web, but few studies have examined its effects on the insects that feed on Se-accumulating plants, particularly pollinators. In laboratory bioassays, we used proboscis extension reflex (PER) and taste perception to determine if the presence of Se affected the gustatory response of honey bee (Apis mellifera L., Hymenoptera: Apidae) foragers. Antennae and proboscises were stimulated with both organic (selenomethionine) and inorganic (selenate) forms of Se that commonly occur in Se-accumulating plants. Methionine was also tested. Each compound was dissolved in 1 M sucrose at 5 concentrations, with sucrose alone as a control. Antennal stimulation with selenomethionine and methionine reduced PER at higher concentrations. Selenate did not reduce gustatory behaviors. Two hours after being fed the treatments, bees were tested for sucrose response threshold. Bees fed selenate responded less to sucrose stimulation. Mortality was higher in bees chronically dosed with selenate compared with a single dose. Selenomethionine did not increase mortality except at the highest concentration. Methionine did not significantly impact survival. Our study has shown that bees fed selenate were less responsive to sucrose, which may lead to a reduction in incoming floral resources needed to support coworkers and larvae in the field. If honey bees forage on nectar containing Se (particularly selenate), reductions in population numbers may occur due to direct toxicity. Given that honey bees are willing to consume food resources containing Se and may not avoid Se compounds in the plant tissues on which they are foraging, they may suffer similar adverse effects as seen in other insect guilds.

Selenium Toxicity to Honey Bee (Apis mellifera L.) Pollinators: Effects on Behaviors and Survival

PubMed Central

Hladun, Kristen R.; Smith, Brian H.; Mustard, Julie A.; Morton, Ray R.; Trumble, John T.

2012-01-01

We know very little about how soil-borne pollutants such as selenium (Se) can impact pollinators, even though Se has contaminated soils and plants in areas where insect pollination can be critical to the functioning of both agricultural and natural ecosystems. Se can be biotransferred throughout the food web, but few studies have examined its effects on the insects that feed on Se-accumulating plants, particularly pollinators. In laboratory bioassays, we used proboscis extension reflex (PER) and taste perception to determine if the presence of Se affected the gustatory response of honey bee (Apis mellifera L., Hymenoptera: Apidae) foragers. Antennae and proboscises were stimulated with both organic (selenomethionine) and inorganic (selenate) forms of Se that commonly occur in Se-accumulating plants. Methionine was also tested. Each compound was dissolved in 1 M sucrose at 5 concentrations, with sucrose alone as a control. Antennal stimulation with selenomethionine and methionine reduced PER at higher concentrations. Selenate did not reduce gustatory behaviors. Two hours after being fed the treatments, bees were tested for sucrose response threshold. Bees fed selenate responded less to sucrose stimulation. Mortality was higher in bees chronically dosed with selenate compared with a single dose. Selenomethionine did not increase mortality except at the highest concentration. Methionine did not significantly impact survival. Our study has shown that bees fed selenate were less responsive to sucrose, which may lead to a reduction in incoming floral resources needed to support coworkers and larvae in the field. If honey bees forage on nectar containing Se (particularly selenate), reductions in population numbers may occur due to direct toxicity. Given that honey bees are willing to consume food resources containing Se and may not avoid Se compounds in the plant tissues on which they are foraging, they may suffer similar adverse effects as seen in other insect guilds. PMID:22514621

Selenium Sequestration in a Cationic Layered Rare Earth Hydroxide: A Combined Batch Experiments and EXAFS Investigation.

PubMed

Zhu, Lin; Zhang, Linjuan; Li, Jie; Zhang, Duo; Chen, Lanhua; Sheng, Daopeng; Yang, Shitong; Xiao, Chengliang; Wang, Jianqiang; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

2017-08-01

Selenium is of great concern owing to its acutely toxic characteristic at elevated dosage and the long-term radiotoxicity of 79 Se. The contents of selenium in industrial wastewater, agricultural runoff, and drinking water have to be constrained to a value of 50 μg/L as the maximum concentration limit. We reported here the selenium uptake using a structurally well-defined cationic layered rare earth hydroxide, Y 2 (OH) 5 Cl·1.5H 2 O. The sorption kinetics, isotherms, selectivity, and desorption of selenite and selenate on Y 2 (OH) 5 Cl·1.5H 2 O at pH 7 and 8.5 were systematically investigated using a batch method. The maximum sorption capacities of selenite and selenate are 207 and 124 mg/g, respectively, both representing the new records among those of inorganic sorbents. In the low concentration region, Y 2 (OH) 5 Cl·1.5H 2 O is able to almost completely remove selenium from aqueous solution even in the presence of competitive anions such as NO 3 - , Cl - , CO 3 2- , SO 4 2- , and HPO 4 2- . The resulting concentration of selenium is below 10 μg/L, well meeting the strictest criterion for the drinking water. The selenate on loaded samples could be desorbed by rinsing with concentrated noncomplexing NaCl solutions whereas complexing ligands have to be employed to elute selenite for the material regeneration. After desorption, Y 2 (OH) 5 Cl·1.5H 2 O could be reused to remove selenate and selenite. In addition, the sorption mechanism was unraveled by the combination of EDS, FT-IR, Raman, PXRD, and EXAFS techniques. Specifically, the selenate ions were exchanged with chloride ions in the interlayer space, forming outer-sphere complexes. In comparison, besides anion exchange mechanism, the selenite ions were directly bound to the Y 3+ center in the positively charged layer of [Y 2 (OH) 5 (H 2 O)] + through strong bidentate binuclear inner-sphere complexation, consistent with the observation of the higher uptake of selenite over selenate. The results presented in this work confirm that the cationic layered rare earth hydroxide is an emerging and promising material for efficient removal of selenite and selenate as well as other anionic environmental pollutants.

Selection of superior salt/boron tolerant Stanleya pinnata genotypes and quantification of their selenium phytoremediation abilities in drainage sediment.

USDA-ARS?s Scientific Manuscript database

The semi-metallic mineral Se, a naturally-occurring trace element, is primarily found as selenate originating from sedimentary and shale rock formations, e.g., in the western side of the San Joaquin Valley of central California (WSJV). Because selenate-Se is water soluble, bioavailable and biomagnif...

Dehydration-driven evolution of topological complexity in ethylamonium uranyl selenates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru; Krivovichev, Sergey V.; Tananaev, Ivan G.

Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C{sub 2}H{sub 8}N){sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) (I), (C{sub 2}H{sub 8}N){sub 3}[(UO{sub 2})(SeO{sub 4}){sub 2}(HSeO{sub 4})] (II), (C{sub 2}H{sub 8}N)[(UO{sub 2})(SeO{sub 4})(HSeO{sub 3})] (III), and (C{sub 2}H{sub 8}N)(H{sub 3}O)[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (IV) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H{sub 2}O content. - Graphical abstract: Single crystals ofmore » four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules have been prepared by isothermal evaporation from aqueous solutions. Structural analysis and information-based topological complexity calculations points to the possible sequence of crystalline phases formation, showing both topological and structural branches of evolution. - Highlights: • Single crystals of four novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • Dehydration processes drives the evolution of topological complexity of 1D and 2D structural units.« less

The role of interparticle heterogeneities in the selenization pathway of Cu-Zn-Sn-S nanoparticle thin films: A real-time study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Nathaniel J.; Mainz, Roland; Walker, Bryce C.

2015-06-10

Real-time energy dispersive x-ray diffraction (EDXRD) analysis has been utilized to observe the selenization of Cu-Zn-Sn-S nanoparticle films coated from three nanoparticle populations: Cu- and Sn-rich particles roughly 5 nm in size, Zn-rich nanoparticles ranging from 10 to 20 nm in diameter, and a mixture of both types of nanoparticles (roughly 1:1 by mass), which corresponds to a synthesis recipe yielding CZTSSe solar cells with reported total-area efficiencies as high as 7.9%. The EDXRD studies presented herein show that the formation of copper selenide intermediates during the selenization of mixed-particle films can be primarily attributed to the small, Cu- andmore » Sn-rich particles. Moreover, the formation of these copper selenide phases represents the first stage of the CZTSSe grain growth mechanism. The large, Zn-rich particles subsequently contribute their composition to form micrometer-sized CZTSSe grains. In conclusion, these findings enable further development of a previously proposed selenization pathway to account for the roles of interparticle heterogeneities, which in turn provides a valuable guide for future optimization of processes to synthesize high quality CZTSSe absorber layers.« less

Comparison of the metabolism of inorganic and organic selenium species between two selenium accumulator plants, garlic and Indian mustard.

PubMed

Ogra, Yasumitsu; Ogihara, Yurie; Anan, Yasumi

2017-01-25

The metabolism of selenomethionine (SeMet) in two major selenium (Se) accumulator plants, garlic and Indian mustard, was compared to that of stable isotope labeled selenate. Indian mustard more efficiently transported Se from roots to leaves than garlic. In addition, Indian mustard accumulated larger amounts of Se than garlic. γ-Glutamyl-Se-methylselenocysteine (γ-GluMeSeCys) and Se-methylselenocysteine (MeSeCys) were the common metabolites of selenate and SeMet in garlic and Indian mustard. Indian mustard had a specific metabolic pathway to selenohomolanthionine (SeHLan) from both inorganic and organic Se species. SeMet was a more effective fertilizer for cultivating Se-enriched plants than selenate in terms of the production of selenoamino acids.

Global lunar-surface mapping experiment using the Lunar Imager/Spectrometer on SELENE

NASA Astrophysics Data System (ADS)

Haruyama, Junichi; Matsunaga, Tsuneo; Ohtake, Makiko; Morota, Tomokatsu; Honda, Chikatoshi; Yokota, Yasuhiro; Torii, Masaya; Ogawa, Yoshiko

2008-04-01

The Moon is the nearest celestial body to the Earth. Understanding the Moon is the most important issue confronting geosciences and planetary sciences. Japan will launch the lunar polar orbiter SELENE (Kaguya) (Kato et al., 2007) in 2007 as the first mission of the Japanese long-term lunar exploration program and acquire data for scientific knowledge and possible utilization of the Moon. An optical sensing instrument called the Lunar Imager/Spectrometer (LISM) is loaded on SELENE. The LISM requirements for the SELENE project are intended to provide high-resolution digital imagery and spectroscopic data for the entire lunar surface, acquiring these data for scientific knowledge and possible utilization of the Moon. Actually, LISM was designed to include three specialized sub-instruments: a terrain camera (TC), a multi-band imager (MI), and a spectral profiler (SP). The TC is a high-resolution stereo camera with 10-m spatial resolution from a SELENE nominal altitude of 100 km and a stereo angle of 30° to provide stereo pairs from which digital terrain models (DTMs) with a height resolution of 20 m or better will be produced. The MI is a multi-spectral imager with four and five color bands with 20 m and 60 m spatial resolution in visible and near-infrared ranges, which will provide data to be used to distinguish the geological units in detail. The SP is a line spectral profiler with a 400-m-wide footprint and 300 spectral bands with 6-8 nm spectral resolution in the visible to near-infrared ranges. The SP data will be sufficiently powerful to identify the lunar surface's mineral composition. Moreover, LISM will provide data with a spatial resolution, signal-to-noise ratio, and covered spectral range superior to that of past Earth-based and spacecraft-based observations. In addition to the hardware instrumentation, we have studied operation plans for global data acquisition within the limited total data volume allotment per day. Results show that the TC and MI can achieve global observations within the restrictions by sharing the TC and MI observation periods, adopting appropriate data compression, and executing necessary SELENE orbital plane change operations to ensure global coverage by MI. Pre-launch operation planning has resulted in possible global TC high-contrast imagery, TC stereoscopic imagery, and MI 9-band imagery in one nominal mission period. The SP will also acquire spectral line profiling data for nearly the entire lunar surface. The east-west interval of the SP strip data will be 3-4 km at the equator by the end of the mission and shorter at higher latitudes. We have proposed execution of SELENE roll cant operations three times during the nominal mission period to execute calibration site observations, and have reached agreement on this matter with the SELENE project. We present LISM global surface mapping experiments for instrumentation and operation plans. The ground processing systems and the data release plan for LISM data are discussed briefly.

Selenium deficiency occurs in some patients with moderate-to-severe cirrhosis and can be corrected by administration of selenate but not selenomethionine: a randomized controlled trial123

PubMed Central

Burk, Raymond F; Hill, Kristina E; Motley, Amy K; Byrne, Daniel W; Norsworthy, Brooke K

2015-01-01

Background: Selenomethionine, which is the principal dietary form of selenium, is metabolized by the liver to selenide, which is the form of the element required for the synthesis of selenoproteins. The liver synthesizes selenium-rich selenoprotein P (SEPP1) and secretes it into the plasma to supply extrahepatic tissues with selenium. Objectives: We conducted a randomized controlled trial to determine whether cirrhosis is associated with functional selenium deficiency (the lack of selenium for the process of selenoprotein synthesis even though selenium intake is not limited) and, if it is, whether the deficiency is associated with impairment of selenomethionine metabolism. Design: Patients with Child-Pugh (C-P) classes A, B, and C (mild, moderate, and severe, respectively) cirrhosis were supplemented with a placebo or supranutritional amounts of selenium as selenate (200 or 400 μg/d) or as selenomethionine (200 μg/d) for 4 wk. Plasma SEPP1 concentration and glutathione peroxidase (GPX) activity, the latter due largely to the selenoprotein GPX3 secreted by the kidneys, were measured before and after supplementation. Results: GPX activity was increased more by both doses of selenate than by the placebo in C-P class B patients. The activity was not increased more by selenomethionine supplementation than by the placebo in C-P class B patients. Plasma selenium was increased more by 400 μg Se as selenate than by the placebo in C-P class C patients. Within the groups who responded to selenate, there was a considerable variation in responses. Conclusion: These results indicate that severe cirrhosis causes mild functional selenium deficiency in some patients that is associated with impaired metabolism of selenomethionine. This trial was registered at clinicaltrials.gov as NCT00271245. PMID:26468123

Uptake and speciation of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate.

PubMed

Larsen, Erik H; Lobinski, Ryszard; Burger-Meÿer, Karin; Hansen, Marianne; Ruzik, Rafal; Mazurowska, Lena; Rasmussen, Peter Have; Sloth, Jens J; Scholten, Olga; Kik, Chris

2006-07-01

The scope of the work was to investigate the influence of selenate fertilisation and the addition of symbiotic fungi (mycorrhiza) to soil on selenium and selenium species concentrations in garlic. The selenium species were extracted from garlic cultivated in experimental plots by proteolytic enzymes, which ensured liberation of selenium species contained in peptides or proteins. Separate extractions using an aqueous solution of enzyme-deactivating hydroxylamine hydrochloride counteracted the possible degradation of labile selenium species by enzymes (such as alliinase) that occur naturally in garlic. The selenium content in garlic, which was analysed by ICP-MS, showed that addition of mycorrhiza to the natural soil increased the selenium uptake by garlic tenfold to 15 microg g(-1) (dry mass). Fertilisation with selenate and addition of mycorrhiza strongly increased the selenium content in garlic to around one part per thousand. The parallel analysis of the sample extracts by cation exchange and reversed-phase HPLC with ICP-MS detection showed that gamma-glutamyl-Se-methyl-selenocysteine amounted to 2/3, whereas methylselenocysteine, selenomethionine and selenate each amounted to a few percent of the total chromatographed selenium in all garlic samples. Se-allyl-selenocysteine and Se-propyl-selenocysteine, which are selenium analogues of biologically active sulfur-containing amino acids known to occur in garlic, were searched for but not detected in any of the extracts. The amendment of soil by mycorrhiza and/or by selenate increased the content of selenium but not the distribution of detected selenium species in garlic. Finally, the use of two-dimensional HPLC (size exclusion followed by reversed-phase) allowed the structural characterisation of gamma-glutamyl-Se-methyl-selenocysteine and gamma-glutamyl-Se-methyl-selenomethionine in isolated chromatographic fractions by quadrupole time-of-flight mass spectrometry.

The intensity of tyrosine nitration is associated with selenite and selenate toxicity in Brassica juncea L.

PubMed

Molnár, Árpád; Feigl, Gábor; Trifán, Vanda; Ördög, Attila; Szőllősi, Réka; Erdei, László; Kolbert, Zsuzsanna

2018-01-01

Selenium phytotoxicity involves processes like reactive nitrogen species overproduction and nitrosative protein modifications. This study evaluates the toxicity of two selenium forms (selenite and selenate at 0µM, 20µM, 50µM and 100µM concentrations) and its correlation with protein tyrosine nitration in the organs of hydroponically grown Indian mustard (Brassica juncea L.). Selenate treatment resulted in large selenium accumulation in both Brassica organs, while selenite showed slight root-to-shoot translocation resulting in a much lower selenium accumulation in the shoot. Shoot and root growth inhibition and cell viability loss revealed that Brassica tolerates selenate better than selenite. Results also show that relative high amounts of selenium are able to accumulate in Brassica leaves without obvious visible symptoms such as chlorosis or necrosis. The more severe phytotoxicity of selenite was accompanied by more intense protein tyrosine nitration as well as alterations in nitration pattern suggesting a correlation between the degree of Se forms-induced toxicities and nitroproteome size, composition in Brassica organs. These results imply the possibility of considering protein tyrosine nitration as novel biomarker of selenium phytotoxicity, which could help the evaluation of asymptomatic selenium stress of plants. Copyright © 2017 Elsevier Inc. All rights reserved.

Toxicity of seleno-l-methionine, seleno-dl-methionine, high selenium wheat, and selenized yeast to mallard ducklings

USGS Publications Warehouse

Heinz, G.H.; Hoffman, D.J.; LeCaptain, L.J.

1996-01-01

The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 ?g/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 ?g/g selenium as seleno-DL-methionine (100%) or 30 ?g/g selenium from high selenium yeast (88%). In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 ?g/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. The greater toxicity of the L form of selenomethionine was probably related to the palatability or nutritional nature of the wheat-based diet used in experiment 1, but the exact reason for the difference between the DL and L forms is unknown. Biologically incorporated selenium, derived from high selenium wheat was no more toxic than selenium derived from the two purified forms of selenomethionine, and the selenium in selenized yeast was not as toxic as that in the two forms of selenomethionine.

Toxicity of nutritionally available selenium compounds in primary and transformed hepatocytes.

PubMed

Weiller, Markus; Latta, Markus; Kresse, Matthias; Lucas, Rudolf; Wendel, Albrecht

2004-09-01

The essential trace element selenium is also toxic at low doses. Since supplementation of selenium is discussed as cancer prophylaxis, we investigated whether or not bioavailable selenium compounds are selectively toxic on malignant cells by comparing primary and transformed liver cells as to the extent and mode of cell death. Sodium selenite and selenate exclusively induced necrosis in a concentration-dependent manner in all cell types investigated. In primary murine hepatocytes, the EC50 was 20 microM for selenite, 270 microM for selenate, and 30 microM for Se-methionine. In the human carcinoma cell line HepG2, the EC50 for selenite was 40 microM, and for selenate 1.1 mM, whereas Se-methionine was essentially non-toxic up to 10 mM. Similar results were found in murine Hepa1-6 cells. Exposure of primary murine cells to selenate or selenite resulted in increased lipid peroxidation. Toxicity was inhibited by superoxide dismutase plus catalase, indicating an important role for reactive oxygen intermediates. In primary hepatocytes, metabolical depletion of intracellular ATP by the ketohexose tagatose, significantly decreased the cytotoxicity of Se-methionine, while the one of selenite was increased. These data do not provide any in vitro evidence that bioavailable selenium compounds induce preferentially apoptotic cell death or selectively kill transformed hepatocytes.

Optimization of selenizing conditions for Seleno-Lentinan and its characteristics.

PubMed

Ren, Guangming; Li, Koukou; Hu, Yang; Yu, Min; Qu, Juanjuan; Xu, Xiuhong

2015-11-01

Lentinan was successfully modified with nitric acid-sodium selenite method based on L9(3(4)) orthogonal experiments. The optimum selenizing conditions were obtained according to selenium conversion rate as follows: Lentinan of 1.0g, pH of 4.5, temperature of 70°C and sodium selenite of 1.50g. The antioxidant activity assays in vitro (DPPH, reducing power, superoxide radicals and hydroxyl radicals) proved that Lentinan had stronger antioxidant activity after selenizing. The elevations of serum alanine aminotransferase and aspartate aminotransferase, as well as the abnormal hepatic architecture, verified that oral administration of Seleno-Lentinan (SL2-1) markedly alleviated oxidative damage in the liver of mice induced by D-gal. In addition, SL2-1 significantly increased total antioxidant capacity, activities and protein expressions of catalase and glutathione peroxidase and lowered malondialdehyde levels in serum and liver. Fourier transform infrared spectroscopy analysis indicated that selenium of SL2-1 was mostly existed as the formations of OSeO, SeO and SeOC. Scanning electron microscope coupled with energy dispersive X-ray spectroscopy analysis revealed that the surface structure and elemental components of Lentinan significantly changed after selenizing. The results are instructive for the development of organic selenium-supplement resource. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of selenium in dietary supplements using elemental speciation.

PubMed

Kubachka, Kevin M; Hanley, Traci; Mantha, Madhavi; Wilson, Robert A; Falconer, Travis M; Kassa, Zena; Oliveira, Aline; Landero, Julio; Caruso, Joseph

2017-03-01

Selenium-enriched dietary supplements containing various selenium compounds are readily available to consumers. To ensure proper selenium intake and consumer confidence, these dietary supplements must be safe and have accurate label claims. Varying properties among selenium species requires information beyond total selenium concentration to fully evaluate health risk/benefits A LC-ICP-MS method was developed and multiple extraction methods were implemented for targeted analysis of common "seleno-amino acids" and related oxidation products, selenate, selenite, and other species relatable to the quality and/or accuracy of the labeled selenium ingredients. Ultimately, a heated water extraction was applied to recover selenium species from non-selenized yeast supplements in capsule, tablet, and liquid forms. For selenized yeast supplements, inorganic selenium was monitored as a means of assessing selenium yeast quality. A variety of commercially available selenium supplements were evaluated and discrepancies between labeled ingredients and detected species were noted. Published by Elsevier Ltd.

Evaluation of selenium in dietary supplements using elemental speciation

PubMed Central

Kubachka, Kevin M.; Hanley, Traci; Mantha, Madhavi; Wilson, Robert A.; Falconer, Travis M.; Kassa, Zena; Oliveira, Aline; Landero, Julio; Caruso, Joseph

2016-01-01

Selenium-enriched dietary supplements containing various selenium compounds are readily available to consumers. To ensure proper selenium intake and consumer confidence, these dietary supplements must be safe and have accurate label claims. Varying properties among selenium species requires information beyond total selenium concentration to fully evaluate health risk/benefits A LC-ICP-MS method was developed and multiple extraction methods were implemented for targeted analysis of common “seleno-amino acids” and related oxidation products, selenate, selenite, and other species relatable to the quality and/or accuracy of the labeled selenium ingredients. Ultimately, a heated water extraction was applied to recover selenium species from non-selenized yeast supplements in capsule, tablet, and liquid forms. For selenized yeast supplements, inorganic selenium was monitored as a means of assessing selenium yeast quality. A variety of commercially available selenium supplements were evaluated and discrepancies between labeled ingredients and detected species were noted. PMID:27719915

Kesterite Cu2ZnSn(S,Se)4 Solar Cells with beyond 8% Efficiency by a Sol-Gel and Selenization Process.

PubMed

Liu, Fangyang; Zeng, Fangqin; Song, Ning; Jiang, Liangxing; Han, Zili; Su, Zhenghua; Yan, Chang; Wen, Xiaoming; Hao, Xiaojing; Liu, Yexiang

2015-07-08

A facile sol-gel and selenization process has been demonstrated to fabricate high-quality single-phase earth abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic absorbers. The structure and band gap of the fabricated CZTSSe can be readily tuned by varying the [S]/([S] + [Se]) ratios via selenization condition control. The effects of [S]/([S] + [Se]) ratio on device performance have been presented. The best device shows 8.25% total area efficiency without antireflection coating. Low fill factor is the main limitation for the current device efficiency compared to record efficiency device due to high series resistance and interface recombination. By improving film uniformity, eliminating voids, and reducing the Mo(S,Se)2 interfacial layer, a further boost of the device efficiency is expected, enabling the proposed process for fabricating one of the most promising candidates for kesterite solar cells.

Selenium adsorption to aluminum-based water treatment residuals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ippolito, James A.; Scheckel, Kirk G.; Barbarick, Ken A.

2009-09-02

Aluminum-based water treatment residuals (WTR) can adsorb water- and soil-borne P, As(V), As(III), and perchlorate, and may be able to adsorb excess environmental selenium. WTR, clay minerals, and amorphous aluminum hydroxide were shaken for 24 h in selenate or selenite solutions at pH values of 5-9, and then analyzed for selenium content. Selenate and selenite adsorption edges were unaffected across the pH range studied. Selenate adsorbed on to WTR, reference mineral phases, and amorphous aluminum hydroxide occurred as outer sphere complexes (relatively loosely bound), while selenite adsorption was identified as inner-sphere complexation (relatively tightly bound). Selenite sorption to WTR inmore » an anoxic environment reduced Se(IV) to Se(0), and oxidation of Se(0) or Se(IV) appeared irreversible once sorbed to WTR. Al-based WTR could play a favorable role in sequestering excess Se in affected water sources.« less

Sorption and speciation of selenium in boreal forest soil.

PubMed

Söderlund, Mervi; Virkanen, Juhani; Holgersson, Stellan; Lehto, Jukka

2016-11-01

Sorption and speciation of selenium in the initial chemical forms of selenite and selenate were investigated in batch experiments on humus and mineral soil samples taken from a 4-m deep boreal forest soil excavator pit on Olkiluoto Island, on the Baltic Sea coast in southwestern Finland. The HPLC-ICP-MS technique was used to monitor any possible transformations in the selenium liquid phase speciation and to determine the concentrations of selenite and selenate in the samples for calculation of the mass distribution coefficient, K d , for both species. Both SeO 3 2- and SeO 4 2- proved to be resistant forms in the prevailing soil conditions and no changes in selenium liquid phase speciation were seen in the sorption experiments in spite of variations in the initial selenium species, incubation time or conditions, pH, temperature or microbial activity. Selenite sorption on the mineral soil increased with time in aerobic conditions whilst the opposite trend was seen for the anaerobic soil samples. Selenite retention correlated with the contents of organic matter and weakly crystalline oxides of aluminum and iron, solution pH and the specific surface area. Selenate exhibited poorer sorption on soil than selenite and on average the K d values were 27-times lower. Mineral soil was more efficient in retaining selenite and selenate than humus, implicating the possible importance of weakly crystalline aluminum and iron oxides for the retention of oxyanions in Olkiluoto soil. Sterilization of the soil samples decreased the retention of selenite, thus implying some involvement of soil microbes in the sorption processes or a change in sample composition, but it produced no effect for selenate. There was no sorption of selenite by quartz, potassium feldspar, hornblende or muscovite. Biotite showed the best retentive properties for selenite in the model soil solution at about pH 8, followed by hematite, plagioclase and chlorite. The K d values for these minerals were 18, 14, 8 and 7 L/kg, respectively. It is proposed that selenite sorption is affected by the structural Fe(II) in biotite, which is capable of inducing the reduction of SeO 3 2- to Se(0). Selenite probably forms a surface complex with Fe(III) atoms on the surface of hematite, thus explaining its retention on this mineral. None of the minerals retained selenate to any extent. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Selenate on Viability and Selenomethionine Accumulation of Chlorella sorokiniana Grown in Batch Culture

PubMed Central

Vílchez, Carlos; Torronteras, Rafael; Vigara, Javier; Gómez-Jacinto, Veronica; Janzer, Nora; Gómez-Ariza, José-Luis; Márová, Ivana

2014-01-01

The aim of this work was to study the effect of Se(+VI) on viability, cell morphology, and selenomethionine accumulation of the green alga Chlorella sorokiniana grown in batch cultures. Culture exposed to sublethal Se concentrations of 40 mg·L−1 (212 μM) decreased growth rates for about 25% compared to control. A selenate EC50 value of 45 mg·L−1 (238.2 μM) was determined. Results showed that chlorophyll and carotenoids contents were not affected by Se exposure, while oxygen evolution decreased by half. Ultrastructural studies revealed granular stroma, fingerprint-like appearance of thylakoids which did not compromise cell activity. Unlike control cultures, SDS PAGE electrophoresis of crude extracts from selenate-exposed cell cultures revealed appearance of a protein band identified as 53 kDa Rubisco large subunit of Chlorella sorokiniana, suggesting that selenate affects expression of the corresponding chloroplast gene as this subunit is encoded in the chloroplast DNA. Results revealed that the microalga was able to accumulate up to 140 mg·kg−1 of SeMet in 120 h of cultivation. This paper shows that Chlorella sorokiniana biomass can be enriched in the high value aminoacid SeMet in batch cultures, while keeping photochemical viability and carbon dioxide fixation activity intact, if exposed to suitable sublethal concentrations of Se. PMID:24688385

Selenate as a novel ligand for keplerate chemistry. New {W72Mo60} keplerates with selenates inside the cavity.

PubMed

Korenev, Vladimir S; Abramov, Pavel A; Vicent, Cristian; Zhdanov, Artem A; Tsygankova, Alphiya R; Sokolov, Maxim N; Fedin, Vladimir P

2015-05-21

The synthesis and characterization of three novel keplerate-type compounds containing the {W72Mo60} mixed-metal core are reported. Complexes (NH4)72[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·150H2O·6(NH4)2SeO4 (1a) and (NH4)25(NH2Me2)47[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·130H2O·3(NH4)2SeO4 (1b) were prepared by ligand substitution from the acetate anionic complex [{W6O21(H2O)5(CH3COO)0.5}12{Mo2O4(CH3COO)}30](48-) and selenate. The selenate anions in keplerate ions [{W6O21(H2O)6}12{Mo2O4(SeO4)}30](72-) are very labile and easily aquate with the formation of [{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20](52-), which was isolated as (NH4)20(NH2Me2)32[{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20]·150H2O (2) and structurally characterized. In the crystal structure of 2 selenate has several coordination modes, preferentially bonding to the {Mo2O4}(2+) units, and, additionally, to the {(W)W5} pentagonal blocks. The compounds have been characterized by elemental analysis, Raman, IR and (77)Se NMR spectroscopy, and by ESI mass spectrometry. Capillary electrophoresis was used for characterization of keplerates in solution for the first time.

Distribution of selenoglucosinolates and their metabolites in Brassica treated with sodium selenate.

PubMed

Matich, Adam J; McKenzie, Marian J; Lill, Ross E; McGhie, Tony K; Chen, Ronan K-Y; Rowan, Daryl D

2015-02-25

In Brassica species, hydrolysis of (methylthio)glucosinolates produces sulfur-containing aglycons which have demonstrated anticancer benefits. Selenized Brassicaceae contain (methylseleno)glucosinolates and their selenium-containing aglycons. As a prelude to biological testing, broccoli, cauliflower, and forage rape plants were treated with sodium selenate and their tap roots, stems, leaves, and florets analyzed for selenoglucosinolates and their Se aglycons. Two new selenoglucosinolates were identified: glucoselenoraphanin in broccoli florets and glucoselenonasturtiin in forage rape roots. A new aglycon, selenoberteroin nitrile, was identified in forage rape. The major selenoglucosinolates were glucoselenoerucin in broccoli, glucoselenoiberverin in cauliflower, and glucoselenoerucin and glucoselenoberteroin in forage rape roots. In broccoli florets, the concentrations of selenglucosinolates exceeded those of their sulfur analogues. Fertilization with selenium slightly reduced (methylthio)glucosinolates and aglycons in the roots, but increased them in the florets, the leaves, and sometimes the stems. These discoveries provide a new avenue for investigating how consumption of Brassica vegetables and their organoselenides may promote human health.

Selenium mobility and distribution in irrigated and nonirrigated alluvial soils

USGS Publications Warehouse

Fio, John L.; Fujii, Roger; Deverel, S.J.

1991-01-01

Dissolution and leaching of soil salts by irrigation water is a primary source of Se to shallow groundwater in the western San Joaquin Valley, California. In this study, the mobility and distribution of selenite and selenate in soils with different irrigation and drainage histories was evaluated using sorption experiments and an advection-dispersion model. The sorption studies showed that selenate (15–12400 µg Se L−1) is not adsorbed to soil, whereas selenite (10–5000 µg Se L−1) is rapidly adsorbed. The time lag between adsorption and desorption of selenite is considerable, indicating a dependence of reaction rate on reaction direction (hysteresis). Selenite adsorption and desorption isotherms were different, and both were described with the Freundlich equation. Model results and chemical analyses of extracts from the soil samples showed that selenite is resistant to leaching and therefore can represent a potential long-term source of Se to groundwater. In contrast, selenate behaves as a conservative constituent under alkaline and oxidized conditions and is easily leached from soil.

Effect of Sn Content in a CuSnZn Metal Precursor on Formation of MoSe2 Film during Selenization in Se+SnSe Vapor

PubMed Central

Yao, Liyong; Ao, Jianping; Jeng, Ming-Jer; Bi, Jinlian; Gao, Shoushuai; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Chang, Liann-Be

2016-01-01

The preparation of Cu2ZnSnSe4 (CZTSe) thin films by the selenization of an electrodeposited copper–tin–zinc (CuSnZn) precursor with various Sn contents in low-pressure Se+SnSex vapor was studied. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) measurements revealed that the Sn content of the precursor that is used in selenization in a low-pressure Se+SnSex vapor atmosphere only slightly affects the elemental composition of the formed CZTSe films. However, the Sn content of the precursor significantly affects the grain size and surface morphology of CZTSe films. A metal precursor with a very Sn-poor composition produces CZTSe films with large grains and a rough surface, while a metal precursor with a very Sn-rich composition procures CZTSe films with small grains and a compact surface. X-ray diffraction (XRD) and SEM revealed that the metal precursor with a Sn-rich composition can grow a thicker MoSe2 thin film at CZTSe/Mo interface than one with a Sn-poor composition, possibly because excess Sn in the precursor may catalyze the formation of MoSe2 thin film. A CZTSe solar cell with an efficiency of 7.94%was realized by using an electrodeposited metal precursor with a Sn/Cu ratio of 0.5 in selenization in a low-pressure Se+SnSex vapor. PMID:28773366

Nutritional and supranutritional levels of selenate differentially suppress prostate tumor growth in adult but not young nude mice.

PubMed

Holmstrom, Alexandra; Wu, Ryan T Y; Zeng, Huawei; Lei, K Y; Cheng, Wen-Hsing

2012-09-01

The inhibitory effect of oral methylseleninic acid or methylselenocysteine administration on cancer cell xenograft development in nude mice is well characterized; however, less is known about the efficacy of selenate and age on selenium chemoprevention. In this study, we tested whether selenate and duration on diets would regulate prostate cancer xenograft in nude mice. Thirty-nine homozygous NU/J nude mice were fed a selenium-deficient, Torula yeast basal diet alone (Se-) or supplemented with 0.15 (Se) or 1.0 (Se+) mg selenium/kg (as Na₂SeO₄) for 6 months in Experiment 1 and for 4 weeks in Experiment 2, followed by a 47-day PC-3 prostate cancer cell xenograft on the designated diet. In Experiment 1, the Se- diet enhanced the initial tumor development on days 11-17, whereas the Se+ diet suppressed tumor growth on days 35-47 in adult nude mice. Tumors grown in Se- mice were loosely packed and showed increased necrosis and inflammation as compared to those in Se and Se+ mice. In Experiment 2, dietary selenium did not affect tumor development or histopathology throughout the time course. In both experiments, postmortem plasma selenium concentrations in Se and Se+ mice were comparable and were twofold greater than those in Se- mice. Taken together, dietary selenate at nutritional and supranutritional levels differentially inhibit tumor development in adult, but not young, nude mice engrafted with PC-3 prostate cancer cells. Copyright © 2012 Elsevier Inc. All rights reserved.

Colorimetric determination of selenium in mineral premixes .

PubMed

Hurlbut, J A; Burkepile, R G; Geisler, C A; Kijak, P J; Rummel, N G

1997-01-01

A method is described for determination of sodium selenite or sodium selenate in mineral-based premixes. It is based on the formation of intense-yellow piazselenol by Se(IV) and 3,3'-diaminobenzidine. Mineral premixes typically contain calcium carbonate as a base material and magnesium carbonate, silicon dioxide, and iron(III) oxide as minor components or additives. In this method, the premix is digested briefly in nitric acid, diluted with water, and filtered to remove any Iron(III) oxide. Ethylenediaminetetraacetic acid and HCl are added to the filtrate, which is heated to near boiling for 1 h to convert any selenate to selenite. After heating, the solution is buffered between pH 2 and 3 with NaOH and formic acid and treated with NH2OH and EDTA; any Se present forms a complex with 3,3'-diaminobenzidine at 60 degrees C. The solution is made basic with NH4OH, and the piazselenol is extracted into toluene. The absorbance of the complex in dried toluene is measured at 420 nm. The method was validated independently by 2 laboratories. Samples analyzed included calcium carbonate fortified with 100, 200, and 300 micrograms Se in the form of sodium selenite or sodium selenate, a calcium carbonate premix containing sodium selenite, a calcium carbonate premix containing sodium selenate, and a commercial premix; 5 replicates of each sample type were analyzed by each laboratory. Average recoveries ranged from 89 to 109% with coefficients of variation from 1.2 to 13.6%.

Progress Report on Landing Site Evaluation for the Next Japanese Lunar Exploration Project: SELENE-2

NASA Astrophysics Data System (ADS)

Saiki, K.; Arai, T.; Araki, H.; Ishihara, Y.; Ohtake, M.; Karouji, Y.; Kobayashi, N.; Sugihara, T.; Haruyama, J.; Honda, C.

2010-12-01

SELENE-2 is the next Japanese lunar exploration project that is planned to be launched by the end of fiscal year 2015. In order to select the landing site candidates which maximize the scientific return from the project, "SELENE-2 Landing Site Research Board" was organized in March, 2010. The board called for scientific proposals with landing site candidates from domestic researchers who are interested in lunar science and members of the Japanese Society for Planetary Sciences, Japan Association of Mineralogical Sciences, the Geochemical Society of Japan, Seismological society of Japan, or the Geodetic society of Japan. At present, we have 35 scientific proposals with over 70 landing site candidates submitted from 21 groups. The proposals were categorized into nine research subjects as follows: 1) Identification of mantle materials, 2) Temporal variation of igneous activity and thermal history of the moon, 3) Lava morphology, 4) Origin of swirl, 5) Crater formation mechanism, 6) Core size, 7) Internal structure (crust - mantle), 8) Origin of the region enriched in heat source elements, and 9) Origin of highland crust. We are evaluating the proposals with the landing sites, and discussing the scientific target of SELENE-2. Within 6 months, we will propose several model missions which execute the scientific exploration with the highest priority today. In our presentation, the present landing site candidates, the policy of the selection, and a plan of a further landing site selection process would be shown.

Variation in electrical properties of gamma irradiated cadmium selenate nanowires

NASA Astrophysics Data System (ADS)

Chauhan, R. P.; Rana, Pallavi; Narula, Chetna; Panchal, Suresh; Choudhary, Ritika

2016-07-01

Preparation of low-dimensional materials attracts more and more interest in the last few years, mainly due to the wide field of potential commercial applications ranging from life sciences, medicine and biotechnology to communication and electronics. One-dimensional systems are the smallest dimension structures that can be used for efficient transport of electrons and thus expected to be critical to the function and integration of nanoscale devices. Nanowires with well controlled morphology and extremely high aspect ratio can be obtained by replicating a nanoporous polymer ion-track membrane with cylindrical pores of controlled dimensions. With this technique, materials can be deposited within the pores of the membrane by electrochemical reduction of the desired ion. In the present study, cadmium selenate nanowires were synthesized potentiostatically via template method. These synthesized nanowires were then exposed to gamma rays by using a 60Co source at the Inter University Accelerator Centre, New Delhi, India. Structural, morphological, electrical and elemental characterizations were made in order to analyze the effect of gamma irradiation on the synthesized nanowires. I-V measurements of cadmium selenate nanowires, before and after irradiation were made with the help of Keithley 2400 source meter and Ecopia probe station. A significant change in the electrical conductivity of cadmium selenate nanowires was found after gamma irradiation. The crystallography of the synthesized nanowires was also studied using a Rigaku X-ray diffractrometer equipped with Cu-Kα radiation. XRD patterns of irradiated samples showed no variation in the peak positions or phase change.

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide

USGS Publications Warehouse

Balistrieri, L.S.; Chao, T.T.

1990-01-01

This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

Human metabolism and renal excretion of selenium compounds after oral ingestion of sodium selenite and selenized yeast dependent on the trimethylselenium ion (TMSe) status.

PubMed

Jäger, Thomas; Drexler, Hans; Göen, Thomas

2016-05-01

A human in vivo metabolism study was carried out to investigate the impact of the trimethylselenium ion (TMSe) status on metabolism and toxicokinetics of sodium selenite and selenized yeast. Nine healthy human volunteers were orally exposed to 200 µg selenium as sodium selenite and seven with selenized yeast (100 µg selenium). In each intervention group, three subjects belong to TMSe eliminators. Blood samples were withdrawn before and up to 6 h after administration. Urine samples were collected before and within 24 h after administration. Total selenium (Se) was quantified in blood plasma and urine and low molecular Se species in urine. Selenium concentration in plasma increased from 84.5 ± 13.2 µg Se/L before to 97.4 ± 13.2 µg Se/L 2-3 h after selenite supplementation and 89.5 ± 12.9 µg Se/L to 92.1 ± 13.9 µg Se/L after selenized yeast intake. The oral ingestion caused an additional Se elimination via urine of 16.9 ± 10.6 µg/24 h (TMSe elim.: 10.8 ± 6.9 µg/24 h; non-TMSe elim.: 20.0 ± 11.3 µg Se/24 h) after selenite exposure and 11.8 ± 4.1 µg/24 h (TMSe elim.: 10.8 ± 4.6 µg/24 h; non-TMSe elim.: 12.6 ± 4.2 µg Se/24 h) after selenized yeast exposure. Methyl-2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (SeSug1) was the main metabolite in all urine samples, whereas TMSe was another main metabolite in TMSe eliminators' urine. After selenite exposure, a small amount of the dose (0.5 ± 0.2 %) was oxidized to selenate and rapidly excreted via urine. With the exception of selenite exposure in TMSe eliminators, the comparison of total Se and the sum of quantified Se species revealed a high renal portion of unidentified species. The study indicated a different metabolism of inorganic and organic Se compounds in human, but also crucial differences of Se metabolism in TMSe eliminators and non-TMSe eliminators.

The effect of sulfate on selenate bioaccumulation in two freshwater primary producers: A duckweed (Lemna minor) and a green alga (Pseudokirchneriella subcapitata).

PubMed

Lo, Bonnie P; Elphick, James R; Bailey, Howard C; Baker, Josh A; Kennedy, Christopher J

2015-12-01

Predicting selenium bioaccumulation is complicated because site-specific conditions, including the ionic composition of water, affect the bioconcentration of inorganic selenium into the food web. Selenium tissue concentrations were measured in Lemna minor and Pseudokirchneriella subcapitata following exposure to selenate and sulfate. Selenium accumulation differed between species, and sulfate reduced selenium uptake in both species, indicating that ionic constituents, in particular sulfate, are important in modifying selenium uptake by primary producers. © 2015 SETAC.

Expression of the ubiE gene of Geobacillus stearothermophilus V in Escherichia coli K-12 mediates the evolution of selenium compounds into the headspace of selenite- and selenate-amended cultures.

PubMed

Swearingen, J W; Fuentes, D E; Araya, M A; Plishker, M F; Saavedra, C P; Chasteen, T G; Vásquez, C C

2006-01-01

The ubiE gene of Geobacillus stearothermophilus V, with its own promoter, was cloned and introduced into Escherichia coli. The cloned gene complemented the ubiE gene deficiency of E. coli AN70. In addition, the expression of this gene in E. coli JM109 resulted in the evolution of volatile selenium compounds when these cells were grown in selenite- or selenate-amended media. These compounds were dimethyl selenide and dimethyl diselenide.

Comparison of methods to determine selenium species in saturation extracts of soils from the western San Joaquin Valley, California

USGS Publications Warehouse

Fio, John L.; Fujii, Roger

1988-01-01

Undigested organic matter in some of the extracts inhibited selenium detection when using the digestion and Sep-Pac C18 methods, but the interference was removed by using the XAD-8 method. Combining XAD-8 resin and activated charcoal was an unacceptable method, because the activated charcoal removed selenite and selenate. Ninety-eight percent of the selenium in the extracts was selenate and about 100 percent of the isolated organic selenium was associated with the humic acid fraction of dissolved-organic matter.

Differential cytochrome content and reductase activity in Geospirillum barnesii strain SeS3

USGS Publications Warehouse

Stolz, J.F.; Gugliuzza, T.; Switzer, Blum J.; Oremland, R.; Martinez, Murillo F.

1997-01-01

The protein composition, cytochrome content, and reductase activity in the dissimilatory selenate-reducing bacterium Geospirillum barnesii strain SeS3, grown with thiosulfate, nitrate, selenate, or fumarate as the terminal electron acceptor, was investigated. Comparison of seven high-molecular-mass membrane proteins (105.3, 90.3, 82.6, 70.2, 67.4, 61.1, and 57.3 kDa) by SDS-PAGE showed that their detection was dependent on the terminal electron acceptor used. Membrane fractions from cells grown on thiosulfate contained a 70.2-kDa c-type cytochrome with absorbance maxima at 552, 522, and 421 nm. A 61.1-kDa c-type cytochrome with absorption maxima at 552, 523, and 423 nm was seen in membrane fractions from cells grown on nitrate. No c-type cytochromes were detected in membrane fractions of either selenate- or fumarate-grown cells. Difference spectra, however, revealed the presence of a cytochrome b554 (absorption maxima at 554, 523, and 422 nm) in membrane fractions from selenate-grown cells and a cytochrome b556 (absorption maxima at 556, 520, and 416 nm) in membrane fractions from fumarate-grown cells. Analysis of reductase activity in the different membrane fractions showed variability in substrate specificity. However, enzyme activity was greatest for the substrate on which the cells had been grown (e.g., membranes from nitrate-grown cells exhibited the greatest activity with nitrate). These results show that protein composition, cytochrome content, and reductase activity are dependent on the terminal electron acceptor used for growth.

Rumen Microorganisms Decrease Bioavailability of Inorganic Selenium Supplements.

PubMed

Galbraith, M L; Vorachek, W R; Estill, C T; Whanger, P D; Bobe, G; Davis, T Z; Hall, J A

2016-06-01

Despite the availability of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study was to determine whether rumen microorganisms (RMO) alter the bioavailability of Se sources commonly used in Se supplements. Rumen microorganisms were isolated from ewes (n = 4) and incubated ex vivo with no Se (control), with inorganic Na selenite or Na selenate, or with organic selenomethionine (SeMet). Total Se incorporated into RMO and the amount of elemental Se formed were determined under equivalent conditions. Incorporation of Se from Na selenite, Na selenate, or SeMet into RMO was measured as fold change compared with control (no added Se). Incorporation of Se into microbial mass was greater for SeMet (13.2-fold greater than no-Se control) compared with inorganic Se supplements (P = 0.02); no differences were observed between inorganic Na selenate (3.3-fold greater than no-Se control) and Na selenite (3.5-fold greater than no-Se control; P = 0.97). Formation of non-bioavailable, elemental Se was less for RMO incubated with SeMet compared with inorganic Se sources (P = 0.01); no differences were observed between Na selenate and Na selenite (P = 0.09). The clinical importance of these results is that the oral bioavailability of organic SeMet should be greater compared with inorganic Se sources because of greater RMO incorporation of Se and decreased formation of elemental Se by RMO.

Evaluation of simultaneous reduction and transport of selenium in saturated soil columns

NASA Astrophysics Data System (ADS)

Guo, Lei; Frankenberger, William T.; Jury, William A.

1999-03-01

Speciation plays an important role in determining the overall leachability of selenium in soil. In this study we present a mathematical model and results of miscible displacement experiments that were conducted to evaluate simultaneous reduction and transport of selenate in saturated soil columns. The experiments were carried out in organic amended (compost manure or gluten) or unamended soil, with O2-sparged or nonsparged influent solution. In all columns, reduction of selenate was fast enough to produce selenite flux in the effluent and elemental Se in the soil profile during a mean residence time of ˜30 hours. Reduction was accelerated in the presence of organic amendments and under low O2 concentrations, resulting in an increased retardation of selenium transport as a whole. The results of our experiments show that although selenate does not sorb to solid surfaces during transport, it reduces rapidly to forms that are strongly retarded. On the basis of simulation with the consecutive reaction and transport model using parameters derived from this study, selenium is expected to be retained near the soil surface, even under extreme leaching conditions.

Bacterial respiration of arsenic and selenium

USGS Publications Warehouse

Stolz, J.F.; Oremland, R.S.

1999-01-01

Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature. Although the bacterial species that have been isolated and characterized are still few in number, they are scattered throughout the bacterial domain and include Gram- positive bacteria, beta, gamma and epsilon Proteobacteria and the sole member of a deeply branching lineage of the bacteria, Chrysiogenes arsenatus. The oxidation of a number of organic substrates (i.e. acetate, lactate, pyruvate, glycerol, ethanol) or hydrogen can be coupled to the reduction of arsenate and selenate, but the actual donor used varies from species to species. Both periplasmic and membrane-associated arsenate and selenate reductases have been characterized. Although the number of subunits and molecular masses differs, they all contain molybdenum. The extent of the environmental impact on the transformation and mobilization of arsenic and selenium by microbial dissimilatory processes is only now being fully appreciated.

The Selenylation Modification of Epimedium Polysaccharide and Isatis Root Polysaccharide and the Immune-enhancing Activity Comparison of Their Modifiers.

PubMed

Li, Xiuping; Hou, Ranran; Yue, Chanjuan; Liu, Jie; Gao, Zhenzhen; Chen, Jin; Lu, Yu; Wang, Deyun; Liu, Cui; Hu, Yuanliang

2016-05-01

Epimedium polysaccharide (EPS) and isatis root polysaccharide (IRPS) were extracted, purified, and selenizingly modified by nitric acid-sodium selenite method to obtain nine selenizing EPSs (sEPSs), sEPS1-sEPS9 and nine selenizing IRPSs (sIRPSs), sIRPS1-sIRPS9, respectively. Their effects on chicken peripheral lymphocyte proliferation in vitro were compared by MTT assay. The results showed that selenium polysaccharides at appropriate concentration could promote lymphocyte proliferation more significantly than unmodified polysaccharides, sEPS5 and sIRPS5 with stronger actions were picked out and injected into the chickens vaccinated with Newcastle disease vaccine in vivo tests. The peripheral lymphocyte proliferation and serum antibody titer were determined. The results showed that sEPS5 and sIRPS5 could elevate serum antibody titer and promote lymphocyte proliferation more significantly than unmodified polysaccharides, sEPS5 possessed the strongest efficacy. These results indicate that selenylation modification can significantly enhance the immune-enhancing activity of EPS and IRPS, and sEPS5 can be as a new-type immunopotentiator of chickens.

Assessment of the anticancer compounds Se-methylselenocysteine and glucosinolates in Se-biofortified broccoli (Brassica oleracea L. var. italica) sprouts and florets.

PubMed

Ávila, Fabricio William; Faquin, Valdemar; Yang, Yong; Ramos, Silvio Junio; Guilherme, Luiz Roberto G; Thannhauser, Theodore W; Li, Li

2013-07-03

Broccoli (Brassica oleracea L. var. italica) is a rich source of chemopreventive compounds. Here, we evaluated and compared the effect of selenium (Se) treatment on the accumulation of anticancer compounds Se-methylselenocysteine (SeMSCys) and glucosinolates in broccoli sprouts and florets. Total Se and SeMSCys content in sprouts increased concomitantly with increasing Se doses. Selenate was superior to selenite in inducing total Se accumulation, but selenite is equally effective as selenate in promoting SeMSCys synthesis in sprouts. Increasing sulfur doses reduced total Se and SeMSCys content in sprouts treated with selenate, but not in those with selenite. Examination of five broccoli cultivars reveals that sprouts generally have better fractional ability than florets to convert inorganic Se into SeMSCys. Distinctive glucosinolate profiles between sprouts and florets were observed, and sprouts contained approximately 6-fold more glucoraphanin than florets. In contrast to florets, glucosinolate content was not affected by Se treatment in sprouts. Thus, Se-enriched broccoli sprouts are excellent for simultaneous accumulation of chemopreventive compounds SeMSCys and glucoraphanin.

Hybridation of different chiral separation techniques with ICP-MS detection for the separation and determination of selenomethionine enantiomers: chiral speciation of selenized yeast.

PubMed

Méndez, S P; González, E B; Sanz-Medel, A

2001-05-01

Enantioseparation and determination of selenomethionine enantiomers in selenized yeast was investigated using chiral separation techniques based on different principles, coupled on-line to inductively coupled plasma mass spectrometry (ICP-MS) for selenium-specific detection. High performance liquid chromatography (HPLC) on a beta-cyclodestrin (beta-CD) column, cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC), gas chromatography (GC) on a Chirasil-L-Val column, and HPLC on a Chirobiotic T column have been investigated as the chiral separation techniques. For HPLC separation on the beta-CD column, and also for CD-MEKC, selenomethionine enantiomers were derivatized with NDA/CN(-). For chiral separation by GC, selenomethionine enantiomers were converted into their N-trifluoroacetyl (TFA)-O-alkyl esters. The developed hybridation methodologies are compared with respect to enantioselectivity, sensitivity and analysis time. The usefulness of the best-suited method [HPLC (Chirobiotic T)-ICP-MS] was demonstrated by its application to the successful chiral speciation of selenium and D-and L-selenomethionine content determination in selenized yeast. Copyright 2001 John Wiley & Sons, Ltd.

Semimicrodetermination of tantalum with selenous acid

USGS Publications Warehouse

Grimaldi, F.S.; Schnepfe, M.M.

1958-01-01

Tantalum is separated and determined gravimetrically by precipitation with selenous acid from a highly acidic solution containing oxalic and tartaric acids. The method is selective for the determination of up to 30 mg. of tantalum pentoxide, and tolerates relatively large amounts of scandium, yttrium, cerium, titanium, zirconium, thorium, vanadium, niobium, molybdenum, tungsten, uranium, iron, aluminum, gallium, tin, lead, antimony, and bismuth. The separation of tantalum from niobium and titanium is not strictly quantitative, and correction is made colorimetrically for the small amounts of niobium and titanium co-precipitating with the tantalum. The method was applied to the determination of tantalum in tantaloniobate ores.

Gaia, Helios, Selene and Ouranos: the three principal celestial bodies and the sky in the ancient Greek cosmogony

NASA Astrophysics Data System (ADS)

Theodossiou, Efstratios; Manimanis, Vassilios N.; Dimitrijević, Milan S.; Mantarakis, Petros

In this article we consider the role of the three principal celestial bodies, the Earth (Gaia), the Sun (Helios) and the Moon (Selene), as well as the Sky (Ouranos) in the ancient Greek cosmogony. This is done by the analysis of antique Greek texts like Orphic Hymns and the literary remains of the writers and philosophers like Aeschylus, (Pseudo) Apollodorus, Apollonius Rhodius, Aristotle, Euripides, Hesiod, Homer, Hyginus, Nonnus, Pausanias, Pindar and Sophocles, as well as by the analysis of texts of Roman writers like Cicero, Ovid and Pliny.

Investigation into the effect on structure of oxoanion doping in Na{sub 2}M(SO{sub 4}){sub 2}·2H{sub 2}O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Driscoll, L.L.; Kendrick, E.; Sharp Laboratories Europe, Oxford Science Park, Edmund Halley Road, Oxford OX4 4GB

2016-10-15

In this paper an investigation into the effect of transition metal ion and selenate/fluorophosphate doping on the structures of Na{sub 2}M(SO{sub 4}){sub 2}·2H{sub 2}O (M=transition metal) materials is reported. In agreement with previous reports, the monoclinic (Kröhnkite) structure is adopted for M=Mn, Fe, Co, Cu, while for the smallest first row divalent transition metal ion, M=Ni, the triclinic (Fairfieldite structure) is adopted. On selenate doping there is a changeover in structure from monoclinic to triclinic for M=Fe, Co, Cu, with the larger Fe{sup 2+} system requiring the highest level of selenate to complete the changeover. Thus the results suggest thatmore » the relative stability of the two structure types is influenced by the relative size of the transition metal: oxoanion group, with the triclinic structure favoured for small transition metals/large oxoanions. The successful synthesis of fluorophosphate doped samples, Na{sub 2}M(SO{sub 4}){sub 2−x}(PO{sub 3}F){sub x}·2H{sub 2}O was also obtained for M=Fe, Co, Cu, with the results showing a changeover in structure from monoclinic to triclinic for M=Co, Cu for very low levels (x=0.1) of fluorophosphate. In the case of M=Fe, the successful synthesis of fluorophosphates samples was achieved for x≤0.3, although no change in cell symmetry was observed. Rather in this particular case, the X-ray diffraction patterns showed evidence for selective peak broadening, attributed to local disorder as a result of the fluorophosphate group disrupting the H-bonding network. Overall the work highlights how isovalent doping can be exploited to alter the structures of Na{sub 2}M(SO{sub 4}){sub 2}·2H{sub 2}O systems. - Graphical abstract: Partial substitution of sulfate in Na{sub 2}M(SO{sub 4}){sub 2}0.2H{sub 2}O (M=Co, Cu) by selenate or fluorophosphate leads to a structural change from the monoclinic Kröhnkite to the triclinic Fairfieldite structure. - Highlights: • The successful synthesis of Na{sub 2}M(SO{sub 4}){sub 2}·2H{sub 2}O (M=transition metal) phases doped with selenate and fluorophosphate. • A change in structure is observed on selenate doping for M=Fe, Co, Cu. • This change in structure is also observed on fluorophosphate doping for M=Co, Cu. • The work highlights how isovalent doping can be exploited to alter the structures of Na{sub 2}M(SO{sub 4}){sub 2}·2H{sub 2}O systems.« less

Contribution of SELENE-2 geodetic measurements to constrain the lunar internal structure

NASA Astrophysics Data System (ADS)

Matsumoto, K.; Kikuchi, F.; Yamada, R.; Iwata, T.; Kono, Y.; Tsuruta, S.; Hanada, H.; Goossens, S. J.; Ishihara, Y.; Kamata, S.; Sasaki, S.

2012-12-01

Internal structure and composition of the Moon provide important clue and constraints on theories for how the Moon formed and evolved. The Apollo seismic network has contributed to the internal structure modeling. Efforts have been made to detect the lunar core from the noisy Apollo data (e.g., [1], [2]), but there is scant information about the structure below the deepest moonquakes at about 1000 km depth. On the other hand, there have been geodetic studies to infer the deep structure of the Moon. For example, LLR (Lunar Laser Ranging) data analyses detected a displacement of the lunar pole of rotation, indicating that dissipation is acting on the rotation arising from a fluid core [3]. Bayesian inversion using geodetic data (such as mass, moments of inertia, tidal Love numbers k2 and h2, and quality factor Q) also suggests a fluid core and partial melt in the lower mantle region [4]. Further improvements in determining the second-degree gravity coefficients (which will lead to better estimates of moments of inertia) and the Love number k2 will help us to better constrain the lunar internal structure. Differential VLBI (Very Long Baseline Interferometry) technique, which was used in the Japanese lunar exploration mission SELENE (Sept. 2007 - June 2009), is expected to contribute to better determining the second-degree potential Love number k2 and low-degree gravity coefficients. SELENE will be followed by the future lunar mission SELENE-2 which will carry both a lander and an orbiter. We propose to put the SELENE-type radio sources on these spacecraft in order to accurately estimate k2 and the low-degree gravity coefficients. By using the same-beam VLBI tracking technique, these parameters will be retrieved through precision orbit determination of the orbiter with respect to the lander which serves as a reference. The VLBI mission with the radio sources is currently one of the mission candidates for SELENE-2. We have conducted a preliminary simulation study on the anticipated k2 accuracy. With the assumed mission duration of about 3 months and the arc length of 14 days, the k2 accuracy is estimated to be better than 1 %, where the uncertainty is evaluated as 10 times the formal error considering the errors in the non-conservative force modeling and in the lander position. We carried out a feasibility study using Bayesian inversion on how well we can constrain the lunar internal structure by the geodetic data to be improved by SELENE-2. It will be shown that such improved geodetic data contribute to narrow the range of the plausible internal structure models, but there are still trade-offs among crust, mantle, and core structures. Preliminary simulation results will be presented to show that the accuracy of core structure estimation will be improved in consequence of better determination of the mantle structure by combining the geodetic data with the seismic data. References [1] Weber et al. (2011), Science, 331, 309-312, doi:10.1126/science.1199375 [2] Garcia eta l. (2011), PEPI, doi:10.1016/j.pepi.2011.06.015 [3] Williams et al. (2001), JGR, 106, E11, 27,933-27,968 [4] Khan and Mosegaard (2005), GRL, 32, L22203, doi:10.1029/2005GL023985

Impact of ovariectomy, high fat diet, and lifestyle modifications on oxidative/antioxidative status in the rat liver.

PubMed

Vuković, Rosemary; Blažetić, Senka; Oršolić, Ivana; Heffer, Marija; Vari, Sandor G; Gajdoš, Martin; Krivošíková, Zora; Kramárová, Patrícia; Kebis, Anton; Has-Schön, Elizabeta

2014-06-01

To estimate the impact of high fat diet and estrogen deficiency on the oxidative and antioxidative status in the liver of the ovariectomized rats, as well as the ameliorating effect of physical activity or consumption of functional food containing bioactive compounds with antioxidative properties on oxidative damage in the rat liver. The study was conducted from November 2012 to April 2013. Liver oxidative damage was determined by lipid peroxidation levels expressed in terms of thiobarbituric acid reactive substances (TBARS), while liver antioxidative status was determined by catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) activities, and glutathione (GSH) content. Sixty-four female Wistar rats were divided into eight groups: sham operated and ovariectomized rats that received either standard diet, high fat diet, or high fat diet supplemented with cereal selenized onion biscuits or high fat diet together with introduction of physical exercise of animals. High fat diet significantly increased TBARS content in the liver compared to standard diet (P=0.032, P=0.030). Furthermore, high fat diet decreased the activities of CAT, GR, and GST, as well as the content of GSH (P<0.050). GPx activity remained unchanged in all groups. Physical activity and consumption of cereal selenized onion biscuits showed protective effect through increased GR activity in sham operated rats (P=0.026, P=0.009), while in ovariectomized group CAT activity was increased (P=0.018) in rats that received cereal selenized onion biscuits. Feeding rats with high fat diet was accompanied by decreased antioxidative enzyme activities and increased lipid peroxidation. Bioactive compounds of cereal selenized onion biscuits showed potential to attenuate the adverse impact of high fat diet on antioxidative status.

Effect of selenization time on the structural and morphological properties of Cu(In,Ga)Se2 thin films absorber layers using two step growth process

NASA Astrophysics Data System (ADS)

Korir, Peter C.; Dejene, Francis B.

2018-04-01

In this work two step growth process was used to prepare Cu(In, Ga)Se2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se2 film. The growth process was done at a fixed temperature of 515 °C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.

Effects on the accumulation of calcium, magnesium, iron, manganese, copper and zinc of adding the two inorganic forms of selenium to solution cultures of Zea mays.

PubMed

Longchamp, M; Angeli, N; Castrec-Rouelle, M

2016-01-01

The addition of selenate or selenite to common fertilizers for crop production could be an effective way of producing selenium-rich food and feed. However, this would be feasible only if the increase in plant selenium (Se) content did not negatively influence the uptake of other essential elements. We therefore need to understand the interactions between Se and other major and trace elements during uptake by the plant. This study aimed to evaluate the influence of inorganic forms of Se on the accumulation of selected macronutrients (Ca and Mg) and micronutrients (Fe, Zn, Mn and Cu). Those essential elements are involved in the oxidative balance of cells. Zea mays seedlings were grown hydroponically in growth chambers in nutrient solutions to which we added 10, 50 or 1000 μg.L(-1) of selenate and/or selenite. Cation accumulation was significantly affected by the addition of 50 μg.L(-1) or 1000 μg.L(-1) Se, but not by the presence of 10 μg.L(-1) of Se in the nutrient solution. The highest concentration (1000 μg.L(-1)) of Se in the nutrient solution affected the accumulation of essential cations in Zea mays: selenate tended to increase the accumulation of Mg, Zn and Mn, whereas a selenate/selenite mixture tended to decrease the accumulation of Ca, Mg, Zn and Mn. Only Fe accumulation was unaffected by Se whatever its form or concentration. Selenium may also affect the distribution of cations on Zea mays. For example, levels of Mg and Zn translocation to the shoots were lower in the presence of selenite. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Gamma-radiation and isotopic effect on the critical behavior in triglycine selenate crystals

NASA Astrophysics Data System (ADS)

Kassem, M. E.; Hamed, A. E.; Abulnasr, L.; Abboudy, S.

1994-11-01

Isotopic effects in pure and γ-irradiated triglycine selenate crystals were investigated using the specific heat ( Cp) technique. The obtained results showed an interesting dependence of the critical behavior of Cp on the deuterium content. With increasing content of deuterium, the character of the phase transition changed from a second order (γ-type) to a first order transition. After γ-irradiation, the behavior of Cp around the phase transition region was essentially affected. The transition temperature, Tc, decreased and Δ Cp depressed, and the transition became broad. It was noted that the effect of γ-irradiation is opposite to the isotopic effect.

Flow injection determination of Se in dietary supplements using TiO2 mediated ultraviolet-photochemical volatile species generation

NASA Astrophysics Data System (ADS)

Nováková, E.; Linhart, O.; Červený, V.; Rychlovský, P.; Hraníček, J.

2017-08-01

This paper proposes a method for determination of selenium content in samples of dietary supplements using TiO2 mediated UV-photochemical vapor generation with quartz furnace atomic spectrometric detection. The flow-injection method was optimized for determination of selenium in the form of selenite or selenate ions. The limits of detection of the proposed method are 0.89 ng mL- 1 and 0.68 ng mL- 1 for selenite and selenate, respectively. Extraction in neutral medium was used for the leaching of selenate and NaOH solution was used for the leaching of selenite. The methods accuracy was verified against the declared amounts of Se in five different samples of over-the-counter dietary supplements and on NIST SRM 3280. The method was also compared to results achieved with determination by electrothermal atomization atomic absorption spectrometry following microwave decomposition. The recovery of selenium during sample preparation was tested by spiking the tablets prior to extraction and estimated to be approximately 100%. An interference study has been carried out to estimate the effect of concomitant elements on the methods accuracy.

Improved efficiency of a large-area Cu(In,Ga)Se₂ solar cell by a nontoxic hydrogen-assisted solid Se vapor selenization process.

PubMed

Wu, Tsung-Ta; Hu, Fan; Huang, Jyun-Hong; Chang, Chia-ho; Lai, Chih-chung; Yen, Yu-Ting; Huang, Hou-Ying; Hong, Hwen-Fen; Wang, Zhiming M; Shen, Chang-Hong; Shieh, Jia-Min; Chueh, Yu-Lun

2014-04-09

A nontoxic hydrogen-assisted solid Se vapor selenization process (HASVS) technique to achieve a large-area (40 × 30 cm(2)) Cu(In,Ga)Se2 (CIGS) solar panel with enhanced efficiencies from 7.1 to 10.8% (12.0% for active area) was demonstrated. The remarkable improvement of efficiency and fill factor comes from improved open circuit voltage (Voc) and reduced dark current due to (1) decreased interface recombination raised from the formation of a widened buried homojunction with n-type Cd(Cu) participation and (2) enhanced separation of electron and hole carriers resulting from the accumulation of Na atoms on the surface of the CIGS film. The effects of microstructural, compositional, and electrical characteristics with hydrogen-assisted Se vapor selenization, including interdiffusion of atoms and formation of buried homojunction, were examined in detail. This methodology can be also applied to CIS (CuInSe2) thin film solar cells with enhanced efficiencies from 5.3% to 8.5% (9.4% for active area) and provides a facile approach to improve quality of CIGS and stimulate the nontoxic progress in the large scale CIGS PV industry.

Evaluation of genotypic variation of broccoli (Brassica oleracea var. italic) in response to selenium treatment.

PubMed

Ramos, Silvio J; Yuan, Youxi; Faquin, Valdemar; Guilherme, Luiz Roberto G; Li, Li

2011-04-27

Broccoli (Brassica oleracea var. italic) fortified with selenium (Se) has been promoted as a functional food. Here, we evaluated 38 broccoli accessions for their capacity to accumulate Se and for their responses to selenate treatment in terms of nutritional qualities and sulfur gene expresion. We found that the total Se content varied with over 2-fold difference among the leaf tissues of broccoli accessions when the plants were treated with 20 μM Na(2)SeO(4). Approximately half of total Se accumulated in leaves was Se-methylselenocysteine and selenomethionine. Transcriptional regulation of adenosine 5'-phosphosulfate sulfurylase and selenocysteine Se-methyltransferase gene expression might contribute to the different levels of Se accumulation in broccoli. Total glucosinolate contents were not affected by the concentration of selenate application for the majority of broccoli accessions. Essential micronutrients (i.e., Fe, Zn, Cu, and Mn) remained unchanged among half of the germplasm. Moreover, the total antioxidant capacity was greatly stimulated by selenate in over half of the accessions. The diverse genotypic variation in Se, glucosinolate, and antioxidant contents among accessions provides the opportunity to breed broccoli cultivars that simultaneously accumulate Se and other health benefit compounds.

Chemical Form and Distribution of Selenium and Sulfur in the Selenium Hyperaccumulator Astragalus bisulcatus1

PubMed Central

Pickering, Ingrid J.; Wright, Carrie; Bubner, Ben; Ellis, Danielle; Persans, Michael W.; Yu, Eileen Y.; George, Graham N.; Prince, Roger C.; Salt, David E.

2003-01-01

In its natural habitat, Astragalus bisulcatus can accumulate up to 0.65% (w/w) selenium (Se) in its shoot dry weight. X-ray absorption spectroscopy has been used to examine the selenium biochemistry of A. bisulcatus. High concentrations of the nonprotein amino acid Se-methylseleno-cysteine (Cys) are present in young leaves of A. bisulcatus, but in more mature leaves, the Se-methylseleno-Cys concentration is lower, and selenate predominates. Seleno-Cys methyltransferase is the enzyme responsible for the biosynthesis of Se-methylseleno-Cys from seleno-Cys and S-methyl-methionine. Seleno-Cys methyltransferase is found to be expressed in A. bisulcatus leaves of all ages, and thus the biosynthesis of Se-methylseleno-Cys in older leaves is limited earlier in the metabolic pathway, probably by an inability to chemically reduce selenate. A comparative study of sulfur (S) and Se in A. bisulcatus using x-ray absorption spectroscopy indicates similar trends for oxidized and reduced Se and S species, but also indicates that the proportions of these differ significantly. These results also indicate that sulfate and selenate reduction are developmentally correlated, and they suggest important differences between S and Se biochemistries. PMID:12644695

Microbial-enhanced Selenium and Iron Biofortification of Wheat (Triticum aestivum L.)--Applications in Phytoremediation and Biofortification.

PubMed

Yasin, Muhammad; El-Mehdawi, Ali Farag; Anwar, Aneela; Pilon-Smits, Elizabeth A H; Faisal, Muhammad

2015-01-01

Selenium (Se) is an essential trace element for humans and other mammals. Most dietary Se is derived from crops. To develop a Se biofortification strategy for wheat, the effect of selenate fertilization and bacterial inoculation on Se uptake and plant growth was investigated. YAM2, a bacterium with 99% similarity to Bacillus pichinotyi, showed many plant growth promoting characteristics. Inoculation with YAM2 enhanced wheat growth, both in the presence and absence of selenate: YAM2-inoculated plants showed significantly higher dry weight, shoot length and spike length compared to un-inoculated plants. Selenate also stimulated wheat growth; Un-inoculated Se-treated plants showed a significantly higher dry weight and shoot length compared to control plants without Se. Bacterial inoculation significantly enhanced Se concentration in wheat kernels (167%) and stems (252%), as well as iron (Fe) levels in kernels (70%) and stems (147%), compared to un-inoculated plants. Inoculated Se-treated plants showed a significant increase in acid phosphatase activity, which may have contributed to the enhanced growth. In conclusion; Inoculation with Bacillus sp. YAM2 is a promising Se biofortification strategy for wheat and potentially other crops.

Distribution and bioaccumulation of selenium in aquatic microcosms

USGS Publications Warehouse

Besser, John M.; Huckins, James N.; Little, Edward E.; La Point, Thomas W.

1989-01-01

Closed-system microcosms were used to study factors affecting the fate of selenium (Se) in aquatic systems. Distribution and bioaccumulation of Se varied among sediment types and Se species. A mixture of dissolved 75Se species (selenate, selenite and selenomethionine) was sorbed more rapidly to fine-textured, highly organic pond sediments than to sandy riverine sediments. Sulfate did not affect the distribution and bioaccumulation of 75Se over the range 80–180 mg SO4 liter−1. When each Se species was labeled separately, selenomethionine was lost from the water column more rapidly than selenate or selenite. Selenium lost from the water column accumulated primarily in sediments, but volatilization was also an important pathway for loss of Se added as selenomethionine. Loss rates of dissolved Se residues were more rapid than rates reported from mesocosm and field studies, suggesting that sediment: water interactions are more important in microcosms than in larger test systems. Daphnids accumulated highest concentrations of Se, followed by periphyton and macrophytes. Selenium added as selenomethionine was bioaccumulated preferentially compared to that added as selenite or selenate. Organoselenium compounds such as selenomethione may thus contribute disproportionately to Se bioaccumulation and toxicity in aquatic organisms.

Dynamics of the phase formation process upon the low temperature selenization of Cu/In-multilayer stacks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oertel, M., E-mail: michael.oertel@uni-jena.de; Ronning, C.

2015-03-14

Phase reactions occurring during a low temperature selenization of thin In/Cu-multilayer stacks were investigated by ex-situ x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS). Therefore, dc-sputtered In/Cu-multilayers onto molybdenum coated soda lime glass were selenized in a high vacuum system at temperatures between 260 and 340 °C with different dwell times and selenium supply. The combination of the results of the phase analysis by XRD and the measurements of the in-depth elemental distribution by EDS allowed a conclusion on the occurring reactions within the layer depth. We found two CuInSe{sub 2} formation processes depending on the applied temperature. Already, atmore » a heater temperature of 260 °C, the CuInSe{sub 2} formation can occur by the reaction of Cu{sub 2−x}Se with In{sub 4}Se{sub 3} and Se. At 340 °C, CuInSe{sub 2} is formed by the reaction of Cu{sub 2−x}Se with InSe and Se. Because both reactions need additional selenium, the selenium supply during the selenization can shift the reaction equilibria either to the metal binaries side or to the CuInSe{sub 2} side. Interestingly, a lower selenium supply shifts the equilibrium to the CuInSe{sub 2} side, because the amount of selenium incorporated into the metallic layer is higher for a lower selenium supply. Most likely, a larger number of grain boundaries are the reason for the stronger selenium incorporation. The results of the phase formation studies were used to design a two stage selenization process to get a defined structure of an indium selenide- and a copper selenide-layer at low temperatures as the origin for a controlled interdiffusion to form the CuInSe{sub 2}-absorber-layer at higher temperatures. The approach delivers a CuInSe{sub 2} absorber which reach total area efficiencies of 11.8% (13.0% active area) in a CuInSe{sub 2}-thin-film solar cell. A finished formation of CuInSe{sub 2} at low temperature was not observed in our experiments but is probably possible for longer dwell times.« less

Studies based on global subsurface radar sounding of the Moon by SELENE (Kaguya) Lunar Radar Sounder (LRS): A summary

NASA Astrophysics Data System (ADS)

Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Kobayashi, T.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Goto, Y.

2015-12-01

The Lunar Radar Sounder (LRS) onboard the SELENE (Kaguya) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 130 million pulses worth of radar sounder data have been obtained [Ono et al., 2010]. Based on the datasets of the first lunar global subsurface radar sounding, Ono et al. [2009] revealed that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Based on the further survey, Pommerol et al. [2010] pointed out the negative correlation of clear subsurface echoes with the maps of ilmenite, and suggested that dense ilmenite attenuates the radar pulse in the basaltic mare lava, and cause the absence of the clear subsurface echoes. That also suggests there are undetected subsurface reflectors especially below the young lava flow units with high ilmenite abundance. Kobayashi et al. [2012] applied synthetic aperture radar (SAR) processing to SELENE LRS data in order to obtain distinct radargram. Taking advantage of analyzing waveform data sent via high data rate telemetry from the Moon, we can perform advanced data analyses on the ground. We started providing the both SAR processed and waveform datasets via SELENE Data Archive (http://l2db.selene.darts.isas.jaxa.jp/index.html.en) since 2015. Oshigami et al. [2014] estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria. The volume was derived from the depth of subsurface reflectors measured by LRS. The volumes of the geologic units were 103 to 104 km3. The average eruption rates were 10-5 to 10-3 km3 yr-1. The estimated volumes of the geologic mare units and average eruption rate showed clear positive correlations with their ages. In the presentation, we are going to review not only the studies mentioned above but also some recent studies such as Ishiyama et al. [2013], and Bando et al. [2015].

Hydrazine-Free Solution-Deposited CuIn(S,Se)2 Solar Cells by Spray Deposition of Metal Chalcogenides.

PubMed

Arnou, Panagiota; van Hest, Maikel F A M; Cooper, Carl S; Malkov, Andrei V; Walls, John M; Bowers, Jake W

2016-05-18

Solution processing of semiconductors, such as CuInSe2 and its alloys (CIGS), can significantly reduce the manufacturing costs of thin film solar cells. Despite the recent success of solution deposition approaches for CIGS, toxic reagents such as hydrazine are usually involved, which introduce health and safety concerns. Here, we present a simple and safer methodology for the preparation of high-quality CuIn(S, Se)2 absorbers from metal sulfide solutions in a diamine/dithiol mixture. The solutions are sprayed in air, using a chromatography atomizer, followed by a postdeposition selenization step. Two different selenization methods are explored resulting in power conversion efficiencies of up to 8%.

Observation of Possible Lava Tube Skylights by SELENE cameras

NASA Astrophysics Data System (ADS)

Haruyama, Junichi; Hiesinger, Harald; van der Bogert, Carolyn

We have discovered three deep hole-structures on the Moon in the Terrain Camera and Multi-band Imager on the SELENE. These holes are large depth to diameter ratios: Marius Hills Hole (MHH) is 65 m in diameter and 88-90 m in depth, Mare Tranquillitatis Hole (MTH) is 120 x 110 m in diameter and 180 m in depth, and Mare Ingenii Hole (MIH) is 140 x 110 m in diameter and deeper than 90 m. No volcanic material from the holes nor dike-relating pit craters is seen around the holes. They are possible lava tube skylights. These holes and possibly connected tubes have a lot of scientific interests and high potentialities as lunar bases.

Status of flexible CIS research at ISET

NASA Technical Reports Server (NTRS)

Basol, B. M.; Kapur, V. K.; Minnick, A.; Halani, A.; Leidholm, C. R.

1994-01-01

Polycrystalline thin film solar cells fabricated on light-weight, flexible substrates are very attractive for space applications. In this work CulnSe2 (CIS) based thin film devices were processed on metallic foil substrates using the selenization technique. CIS deposition method involved reaction of electron-bean evaporated Cu-In precursor layers with a selenizing atmosphere at around 400 C. Several metallic foils such as Mo, Ti, Al, Ni, and Cu were evaluated as possible substrates for these devices. Solar cells with AM1.5 efficiencies of 9.0-9.34 percent and good mechanical integrity were demonstrated on Mo and Ti foils. Monolithic integration of these devices was also demonstrated up to 4 in x 4 in size.

Aggregation and charging of sulfate and amidine latex particles in the presence of oxyanions.

PubMed

Sugimoto, Takuya; Cao, Tianchi; Szilagyi, Istvan; Borkovec, Michal; Trefalt, Gregor

2018-08-15

Electrophoretic mobility and time resolved light scattering are used to measure the effect on charging and aggregation of amidine and sulfate latex particles of different oxyanions namely, phosphate, arsenate, sulfate, and selenate. In the case of negatively charged sulfate latex particles oxyanions represent the coions, while they represent counterions in the case of the positively charged amidine latex. Repulsive interaction between the sulfate latex surface and the coions results in weak ion specific effects on the charging and aggregation. On the other hand the interaction of oxyanions with the amidine latex surface is highly specific. The monovalent dihydrogen phosphate ion strongly adsorbs to the positively charged surface and reverses the charge of the particle. This charge reversal leads also to the restabilization of the amidine latex suspension at the intermediate phosphate concentrations. In the case of dihydrogen arsenate the adsorption to amidine latex surface is weaker and no charge reversal and restabilization occurs. Similar differences are seen between the sulfate and selenate analogues, where selenate adsorbs more strongly to the surface as compared to the sulfate ion and invokes charge reversal. The present results indicate that ion specificity is much more pronounced in the case of counterions. Copyright © 2018 Elsevier Inc. All rights reserved.

Microbial Transformations of Selenium Species of Relevance to Bioremediation

PubMed Central

Eswayah, Abdurrahman S.; Smith, Thomas J.

2016-01-01

Selenium species, particularly the oxyanions selenite (SeO32−) and selenate (SeO42−), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution. PMID:27260359

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization.

PubMed

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-11-04

Tungsten diselenide (WSe 2 ) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe 2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe 2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe 2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe 2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe 2 film texture. Based on the stress state of the W film, a model for growth of the WSe 2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe 2 film.

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization

PubMed Central

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-01-01

Tungsten diselenide (WSe2) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe2 film texture. Based on the stress state of the W film, a model for growth of the WSe2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe2 film. PMID:27812031

Effect of temperature on selenium removal from wastewater by UASB reactors.

PubMed

Dessì, Paolo; Jain, Rohan; Singh, Satyendra; Seder-Colomina, Marina; van Hullebusch, Eric D; Rene, Eldon R; Ahammad, Shaikh Ziauddin; Carucci, Alessandra; Lens, Piet N L

2016-05-01

The effect of temperature on selenium (Se) removal by upflow anaerobic sludge blanket (UASB) reactors treating selenate and nitrate containing wastewater was investigated by comparing the performance of a thermophilic (55 °C) versus a mesophilic (30 °C) UASB reactor. When only selenate (50 μM) was fed to the UASB reactors (pH 7.3; hydraulic retention time 8 h) with excess electron donor (lactate at 1.38 mM corresponding to an organic loading rate of 0.5 g COD L(-1) d(-1)), the thermophilic UASB reactor achieved a higher total Se removal efficiency (94.4 ± 2.4%) than the mesophilic UASB reactor (82.0 ± 3.8%). When 5000 μM nitrate was further added to the influent, total Se removal was again better under thermophilic (70.1 ± 6.6%) when compared to mesophilic (43.6 ± 8.8%) conditions. The higher total effluent Se concentration in the mesophilic UASB reactor was due to the higher concentrations of biogenic elemental Se nanoparticles (BioSeNPs). The shape of the BioSeNPs observed in both UASB reactors was different: nanospheres and nanorods, respectively, in the mesophilic and thermophilic UASB reactors. Microbial community analysis showed the presence of selenate respirers as well as denitrifying microorganisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tracking Se Assimilation and Speciation through the Rice Plant – Nutrient Competition, Toxicity and Distribution

PubMed Central

Eiche, Elisabeth; Riemann, Michael; Nick, Peter; Winkel, Lenny H. E.; Göttlicher, Jörg; Steininger, Ralph; Brendel, Rita; von Brasch, Matthias; Konrad, Gabriele; Neumann, Thomas

2016-01-01

Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations. We studied hydroponic Se uptake for 0–2500 ppb Se, potential phyto-toxicological effects of Se and the speciation of Se along the shoots and roots as a function of added Se species, concentrations and other nutrients supplied. We found that rice germinating directly in a Se environment increased plant-Se by factor 2–16, but that nutrient supplementation is required to prevent phyto-toxicity. XANES data showed that selenite uptake mainly resulted in the accumulation of organic Se in roots, but that selenate uptake resulted in accumulation of selenate in the higher part of the shoot, which is an essential requirement for Se to be transported to the grain. The amount of organic Se in the plant was positively correlated with applied Se concentration. Our results indicate that biofortification of seedlings with selenate is a successful method to increase Se levels in rice. PMID:27116220

Field evidence of selenium bioreduction in a uranium-contaminated aquifer.

PubMed

Williams, Kenneth H; Wilkins, Michael J; N'Guessan, A Lucie; Arey, Bruce; Dodova, Elena; Dohnalkova, Alice; Holmes, Dawn; Lovley, Derek R; Long, Philip E

2013-06-01

Removal of selenium from groundwater was documented during injection of acetate into a uranium-contaminated aquifer near Rifle, Colorado (USA). Bioreduction of aqueous selenium to its elemental form (Se0) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate-amended groundwater. Scanning and transmission electron microscopy revealed close association between Se0 precipitates and cell surfaces, with Se0 aggregates having a diameter of 50-60 nm. Accumulation of Se0 within biofilms occurred over a three-week interval at a rate of c. 9 mg Se0 m(-2) tubing day(-1). Removal was inferred to result from the activity of a mixed microbial community within the biofilms capable of coupling acetate oxidation to the reduction of oxygen, nitrate and selenate. Phylogenetic analysis of the biofilm revealed a community dominated by strains of Dechloromonas sp. and Thauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se0. Enrichment cultures of selenate-respiring microorganisms were readily established using Rifle site groundwater and acetate, with cultures dominated by strains closely related to D. aromatica (96-99% similarity). Predominance of Dechloromonas sp. in recovered biofilms and enrichments suggests this microorganism may play a role in the removal of selenium oxyanions present in Se-impacted groundwaters and sediments.

Selenium speciation methods and application to soil saturation extracts from San Joaquin Valley, California

USGS Publications Warehouse

Fio, John L.; Fujii, Roger

1990-01-01

Methods to determine soluble concentrations of selenite, selenate, and organic Se were evaluated on saturation extracts of soil samples collected from three sites on the Panoche Creek alluvial fan in the western San Joaquin Valley, California. The methods were used in combination with hydride-generation atomic-absorption spectrometry for detection of Se, and included a selective chemical-digestion method and three chromatographic methods using XAD-8 resin, Sep-Pak C18 cartridge, and a combination of XAD-8 resin and activated charcoal. The chromatography methods isolate dissolved organic matter that can inhibit Se detection by hydride-generation atomic-absorption spectrometry. Isolation of hydrophobic organic matter with XAD-8 did not affect concentrations of selenite and selenate, and the isolated organic matter represents a minimal estimation of organic Se. Ninety-eight percent of the Se in the extracts was selenate and about 100% of the isolated organic Se was associated with the humic acid fraction of dissolved organic matter. The depth distribution of Se species in the soil saturation extracts support a hypothesis that the distribution of soluble Se and salinity in these soils is the result of evaporation from a shallow water table and leaching by irrigation water low in Se and salinity.

Selenium biotransformations in an engineered aquatic ecosystem for bioremediation of agricultural wastewater via brine shrimp production.

PubMed

Schmidt, Radomir; Tantoyotai, Prapakorn; Fakra, Sirine C; Marcus, Matthew A; Yang, Soo In; Pickering, Ingrid J; Bañuelos, Gary S; Hristova, Krassimira R; Freeman, John L

2013-05-21

An engineered aquatic ecosystem was specifically designed to bioremediate selenium (Se), occurring as oxidized inorganic selenate from hypersalinized agricultural drainage water while producing brine shrimp enriched in organic Se and omega-3 and omega-6 fatty acids for use in value added nutraceutical food supplements. Selenate was successfully bioremediated by microalgal metabolism into organic Se (seleno-amino acids) and partially removed via gaseous volatile Se formation. Furthermore, filter-feeding brine shrimp that accumulated this organic Se were removed by net harvest. Thriving in this engineered pond system, brine shrimp ( Artemia franciscana Kellogg) and brine fly (Ephydridae sp.) have major ecological relevance as important food sources for large populations of waterfowl, breeding, and migratory shore birds. This aquatic ecosystem was an ideal model for study because it mimics trophic interactions in a Se polluted wetland. Inorganic selenate in drainage water was metabolized differently in microalgae, bacteria, and diatoms where it was accumulated and reduced into various inorganic forms (selenite, selenide, or elemental Se) or partially incorporated into organic Se mainly as selenomethionine. Brine shrimp and brine fly larva then bioaccumulated Se from ingesting aquatic microorganisms and further metabolized Se predominately into organic Se forms. Importantly, adult brine flies, which hatched from aquatic larva, bioaccumulated the highest Se concentrations of all organisms tested.

Field evidence of selenium bioreduction in a uranium-contaminated aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams , K. H.; Wilkins, Michael J.; N'Guessan, A. Lucie

2013-06-01

Removal of selenium from groundwater was documented during injection of acetate into a uraniumcontaminated aquifer near Rifle, Colorado (USA). Bioreduction of aqueous selenium to its elemental form (Se0) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate-amended groundwater. Scanning and transmission electron microscopy revealed close association between Se0 precipitates and cell surfaces, with Se0 aggregates having a diameter of 50-60 nm. Accumulation of Se0 within biofilms occurred over a three-week interval at a rate of c. 9 mg Se0m-2 tubing day-1. Removal was inferred to result from the activity of a mixed microbial community within the biofilmsmore » capable of coupling acetate oxidation to the reduction of oxygen, nitrate and selenate. Phylogenetic analysis of the biofilm revealed a community dominated by strains of Dechloromonas sp. and Thauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se0. Enrichment cultures of selenate-respiring microorganisms were readily established using Rifle site groundwater and acetate, with cultures dominated by strains closely related to D. aromatica (96-99% similarity). Predominance of Dechloromonas sp. in recovered biofilms and enrichments suggests this microorganism may play a role in the removal of selenium oxyanions present in Se-impacted groundwaters and sediments.« less

Comparison of glutathione peroxidase 1 and iodothyronine deiodinase 1 mRNA expression in murine liver after feeding selenite or selenized yeast.

PubMed

Qin, Shunyi; Huang, Kehe; Gao, Jianzhong; Huang, Da; Cai, Tanxi; Pan, Cuiling

2009-01-01

The experiment was conducted to compare the effect of different selenium sources on the expression of glutathione peroxidase 1 (GPx1) and iodothyronine deiodinase 1 (Dio1) mRNA in mice by quantitative real-time PCR. A total of 60 male Kunming mice at average body weight of 20 g were allotted to three groups in a randomized complete block design, namely two treatments and one control. Mice in Group 1 were fed a basal diet as control, while mice in Groups 2 and 3 were fed the basal diet supplemented with 0.1mg/kg selenium as sodium selenite or selenized yeast, respectively. Whole feeding experiment lasted for 30 d. At the end of the feeding trial, liver mRNA levels of GPx1 and Dio1 were determined by quantitative real-time PCR, as well as growth performance, body composition, blood and GPx activity were determined. The results showed that no significant differences in overall growth performance and body composition, including body weight, body length, heart weight, kidney weight and liver weight, were found between the experimental groups (P>0.05). Blood GPx activity increased in all of the selenium supplemented groups compared with control group (P<0.01). However, blood GPx activity in selenized yeast group was higher than that in sodium selenite group (P<0.05). Liver mRNA levels of GPx1 and Dio1 also increased in the two selenium supplemented groups compared with the control group (P<0.05), while there was no significant difference between the sodium selenite and selenized yeast groups (P>0.05). In conclusion, selenium increased the mRNA expression of GPx1 and Dio1 genes in murine liver, and there was no significant difference between the organic or inorganic form of selenium used.

The simulation of lunar gravity field recovery from D-VLBI of Chang’E-1 and SELENE lunar orbiters

NASA Astrophysics Data System (ADS)

Yan, Jianguo; Ping, Jingsong; Matsumoto, K.; Li, Fei

2008-07-01

The lunar gravity field is a foundation to study the lunar interior structure, and to recover the evolution history of the Moon. It is still an open and key topic for lunar science. For above mentioned reasons, it becomes one of the important scientific objectives of recent lunar missions, such as KAGUYA (SELENE) the Japanese lunar mission and Chang’E-1, the Chinese lunar mission. The Chang’E-1 and the SELENE were successfully launched in 2007. It is estimated that these two missions can fly around the Moon longer than 6 months simultaneously. In these two missions, the Chinese new VLBI (Very Long Baseline Interferometry) network will be applied for precise orbit determination (POD) by using a differential VLBI (D-VLBI) method during the mission period. The same-beam D-VLBI technique will contribute to recover the lunar gravity field together with other conventional observables, i.e. R&RR (Range and Range Rate) and multi-way Doppler. Taking VLBI tracking conditions into consideration and using the GEODYNII/SOVLE software of GSFC/NASA/USA [Rowlands, D.D., Marshall, J.A., Mccarthy, J., et al. GEODYN II System Description, vols. 1 5. Contractor Report, Hughes STX Corp. Greenbelt, MD, 1997; Ullman, R.E. SOLVE program: mathematical formulation and guide to user input, Hughes/STX Contractor Report, Contract NAS5-31760. NASA Goddard Space Flight Center, Greenbelt, Maryland, 1994], we simulated the lunar gravity field recovering ability with and without D-VLBI between the Chang’E-1 and SELENE main satellite. The cases of overlapped flying and tracking period of 30 days, 60 days and 90 days have been analyzed, respectively. The results show that D-VLBI tracking between two lunar satellites can improve the gravity field recovery remarkably. The results and methods introduced in this paper will benefit the actual missions.

Nanocrystalline hydroxyapatite doped with selenium oxyanions: a new material for potential biomedical applications.

PubMed

Kolmas, Joanna; Oledzka, Ewa; Sobczak, Marcin; Nałęcz-Jawecki, Grzegorz

2014-06-01

Selenium-substituted hydroxyapatites containing selenate SeO4(2-) or selenite SeO3(2-) ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test. Copyright © 2014 Elsevier B.V. All rights reserved.

A Solid-State NMR Study of Selenium Substitution into Nanocrystalline Hydroxyapatite

PubMed Central

Kolmas, Joanna; Kuras, Marzena; Oledzka, Ewa; Sobczak, Marcin

2015-01-01

The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface. PMID:25997001

Photovoltaic Properties of Selenized CuGa/In Films with Varied Compositions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzzillo, Christopher P.; Mansfield, Lorelle M.; Ramanathan, Kannan

2016-11-21

Thin CuGa/In films with varied compositions were deposited by co-evaporation and then selenized in situ with evaporated selenium. The selenized Cu(In, Ga)Se2 absorbers were used to fabricate 390 solar cells. Cu/(Ga+In) and Ga/(Ga+In) (Cu/III and Ga/III) were independently varied, and photovoltaic performance was optimal at Cu/III of 77-92% for all Ga/III compositions studied (Ga/III ~ 30, 50, and 70%). The best absorbers at each Ga/III composition were characterized with time-resolved photoluminescence, scanning electron microscopy, and secondary ion mass spectrometry, and devices were studied with temperature-dependent current density-voltage, light and electrical biased quantum efficiency, and capacitance-voltage. The best cells with Ga/IIImore » ~ 30, 50, and 70% had efficiencies of 14.5, 14.4, and 12.2% and maximum power temperature coefficients of -0.496, -0.452, and -0.413%/degrees C, respectively. This resulted in the Ga/III ~ 50% champion having the highest efficiency at temperatures greater than 40 degrees C, making it the optimal composition for practical purposes. This optimum is understood as a result of the absorber's band gap grading- where minimum band gap dominates short-circuit current density, maximum space charge region band gap dominates open-circuit voltage, and average absorber band gap dominates maximum power temperature coefficient.« less

Reproducibility and validity of a semi-quantitative FFQ for trace elements.

PubMed

Lee, Yujin; Park, Kyong

2016-09-01

The aim of this study was to test the reproducibility and validity of a self-administered FFQ for the Trace Element Study of Korean Adults in the Yeungnam area (SELEN). Study subjects were recruited from the SELEN cohort selected from rural and urban areas in Yeungnam, Korea. A semi-quantitative FFQ with 146 items was developed considering the dietary characteristics of cohorts in the study area. In a validation study, seventeen men and forty-eight women aged 38-62 years completed 3-d dietary records (DR) and two FFQ over a 3-month period. The validity was examined with the FFQ and DR, and the reproducibility was estimated using partial correlation coefficients, the Bland-Altman method and cross-classification. There were no significant differences between the mean intakes of selected nutrients as estimated from FFQ1, FFQ2 and DR. The median correlation coefficients for all nutrients were 0·47 and 0·56 in the reproducibility and validity tests, respectively. Bland-Altman's index and cross-classification showed acceptable agreement between FFQ1 and FFQ2 and between FFQ2 and DR. Ultimately, 78 % of the subjects were classified into the same and adjacent quartiles for most nutrients. In addition, the weighted κ value indicated that the two methods agreed fairly. In conclusion, this newly developed FFQ was a suitable dietary assessment method for the SELEN cohort study.

Reversal of memory and neuropsychiatric symptoms and reduced tau pathology by selenium in 3xTg-AD mice.

PubMed

Van der Jeugd, Ann; Parra-Damas, Arnaldo; Baeta-Corral, Raquel; Soto-Faguás, Carlos M; Ahmed, Tariq; LaFerla, Frank M; Giménez-Llort, Lydia; D'Hooge, Rudi; Saura, Carlos A

2018-04-24

Accumulation of amyloid-β plaques and tau contribute to the pathogenesis of Alzheimer's disease (AD), but it is unclear whether targeting tau pathology by antioxidants independently of amyloid-β causes beneficial effects on memory and neuropsychiatric symptoms. Selenium, an essential antioxidant element reduced in the aging brain, prevents development of neuropathology in AD transgenic mice at early disease stages. The therapeutic potential of selenium for ameliorating or reversing neuropsychiatric and cognitive behavioral symptoms at late AD stages is largely unknown. Here, we evaluated the effects of chronic dietary sodium selenate supplementation for 4 months in female 3xTg-AD mice at 12-14 months of age. Chronic sodium selenate treatment efficiently reversed hippocampal-dependent learning and memory impairments, and behavior- and neuropsychiatric-like symptoms in old female 3xTg-AD mice. Selenium significantly decreased the number of aggregated tau-positive neurons and astrogliosis, without globally affecting amyloid plaques, in the hippocampus of 3xTg-AD mice. These results indicate that selenium treatment reverses AD-like memory and neuropsychiatric symptoms by a mechanism involving reduction of aggregated tau and/or reactive astrocytes but not amyloid pathology. These results suggest that sodium selenate could be part of a combined therapeutic approach for the treatment of memory and neuropsychiatric symptoms in advanced AD stages.

Preparation of Hollow Fe2O3 Nanorods and Nanospheres by Nanoscale Kirkendall Diffusion, and Their Electrochemical Properties for Use in Lithium-Ion Batteries.

PubMed

Cho, Jung Sang; Park, Jin-Sung; Kang, Yun Chan

2016-12-13

A novel process for the preparation of aggregate-free metal oxide nanopowders with spherical (0D) and non-spherical (1D) hollow nanostructures was introduced. Carbon nanofibers embedded with iron selenide (FeSe) nanopowders with various nanostructures are prepared via the selenization of electrospun nanofibers. Ostwald ripening occurs during the selenization process, resulting in the formation of a FeSe-C composite nanofiber exhibiting a hierarchical structure. These nanofibers transform into aggregate-free hollow Fe 2 O 3 powders via the complete oxidation of FeSe and combustion of carbon. Indeed, the zero- (0D) and one-dimensional (1D) FeSe nanocrystals transform into the hollow-structured Fe 2 O 3 nanopowders via a nanoscale Kirkendall diffusion process, thus conserving their overall morphology. The discharge capacities for the 1000 th cycle of the hollow-structured Fe 2 O 3 nanopowders obtained from the FeSe-C composite nanofibers prepared at selenization temperatures of 500, 800, and 1000 °C at a current density of 1 A g -1 are 932, 767, and 544 mA h g -1 , respectively; and their capacity retentions from the second cycle are 88, 92, and 78%, respectively. The high structural stabilities of these hollow Fe 2 O 3 nanopowders during repeated lithium insertion/desertion processes result in superior lithium-ion storage performances.

Quantification of methionine and selenomethionine in biological samples using multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS).

PubMed

Vu, Dai Long; Ranglová, Karolína; Hájek, Jan; Hrouzek, Pavel

2018-05-01

Quantification of selenated amino-acids currently relies on methods employing inductively coupled plasma mass spectrometry (ICP-MS). Although very accurate, these methods do not allow the simultaneous determination of standard amino-acids, hampering the comparison of the content of selenated versus non-selenated species such as methionine (Met) and selenomethionine (SeMet). This paper reports two approaches for the simultaneous quantification of Met and SeMet. In the first approach, standard enzymatic hydrolysis employing Protease XIV was applied for the preparation of samples. The second approach utilized methanesulfonic acid (MA) for the hydrolysis of samples, either in a reflux system or in a microwave oven, followed by derivatization with diethyl ethoxymethylenemalonate. The prepared samples were then analyzed by multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS). Both approaches provided platforms for the accurate determination of selenium/sulfur substitution rate in Met. Moreover the second approach also provided accurate simultaneous quantification of Met and SeMet with a low limit of detection, low limit of quantification and wide linearity range, comparable to the commonly used gas chromatography mass spectrometry (GC-MS) method or ICP-MS. The novel method was validated using certified reference material in conjunction with the GC-MS reference method. Copyright © 2018. Published by Elsevier B.V.

Selenihalanaerobacter shriftii gen. nov., sp. nov., a halophilic anaerobe from Dead Sea sediments that respires selenate

USGS Publications Warehouse

Switzer, Blum J.; Stolz, J.F.; Oren, A.; Oremland, R.S.

2001-01-01

We isolated an obligately anaerobic halophilic bacterium from the Dead Sea that grew by respiration of selenate. The isolate, designated strain DSSe-1, was a gram-negative, non-motile rod. It oxidized glycerol or glucose to acetate+CO2 with concomitant reduction of selenate to selenite plus elemental selenium. Other electron acceptors that supported anaerobic growth on glycerol were nitrate and trimethylamine-N-oxide; nitrite, arsenate, fumarate, dimethylsulfoxide, thiosulfate, elemental sulfur, sulfite or sulfate could not serve as electron acceptors. Growth on glycerol in the presence of nitrate occurred over a salinity range from 100 to 240 g/l, with an optimum at 210 g/l. Analysis of the 16S rRNA gene sequence suggests that strain DSSe-1 belongs to the order Halanaerobiales, an order of halophilic anaerobes with a fermentative or homoacetogenic metabolism, in which anaerobic respiratory metabolism has never been documented. The highest 16S rRNA sequence similarity (90%) was found with Acetohalobium arabaticum (X89077). On the basis of physiological properties as well as the relatively low homology of 16S rRNA from strain DSSe-1 with known genera, classification in a new genus within the order Halanaerobiales, family Halobacteroidaceae is warranted. We propose the name Selenihalanaerobacter shriftii. Type strain is strain DSSe-1 (ATCC accession number BAA-73).

Growth of strain SES-3 with arsenate and other diverse electron acceptors

USGS Publications Warehouse

Laverman, A.M.; Blum, J.S.; Schaefer, J.K.; Phillips, E.J.P.; Lovley, D.R.; Oremland, R.S.

1995-01-01

The selenate-respiring bacterial strain SES-3 was able to use a variety of inorganic electron acceptors to sustain growth. SES-3 grew with the reduction of arsenate to arsenite, Fe(III) to Fe(II), or thiosulfate to sulfide. It also grew in medium in which elemental sulfur, Mn(IV), nitrite, trimethylamine N-oxide, or fumarate was provided as an electron acceptor. Growth on oxygen was microaerophilic. There was no growth with arsenite or chromate. Washed suspensions of cells grown on selenate or nitrate had a constitutive ability to reduce arsenate but were unable to reduce arsenite. These results suggest that strain SES-3 may occupy a niche as an environmental opportunist by being able to take advantage of a diversity of electron acceptors.

Farside gravity field of the moon from four-way Doppler measurements of SELENE (Kaguya).

PubMed

Namiki, Noriyuki; Iwata, Takahiro; Matsumoto, Koji; Hanada, Hideo; Noda, Hirotomo; Goossens, Sander; Ogawa, Mina; Kawano, Nobuyuki; Asari, Kazuyoshi; Tsuruta, Sei-Itsu; Ishihara, Yoshiaki; Liu, Qinghui; Kikuchi, Fuyuhiko; Ishikawa, Toshiaki; Sasaki, Sho; Aoshima, Chiaki; Kurosawa, Kosuke; Sugita, Seiji; Takano, Tadashi

2009-02-13

The farside gravity field of the Moon is improved from the tracking data of the Selenological and Engineering Explorer (SELENE) via a relay subsatellite. The new gravity field model reveals that the farside has negative anomaly rings unlike positive anomalies on the nearside. Several basins have large central gravity highs, likely due to super-isostatic, dynamic uplift of the mantle. Other basins with highs are associated with mare fill, implying basalt eruption facilitated by developed faults. Basin topography and mantle uplift on the farside are supported by a rigid lithosphere, whereas basins on the nearside deformed substantially with eruption. Variable styles of compensation on the near- and farsides suggest that reheating and weakening of the lithosphere on the nearside was more extensive than previously considered.

Hazard calculations of diffuse reflected laser radiation for the SELENE program

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Babb, Phillip D.

1993-01-01

The hazards from diffuse laser light reflections off water clouds, ice clouds, and fog and from possible specular reflections off ice clouds were assessed with the American National Standards (ANSI Z136.1-1986) for the free-electron-laser parameters under consideration for the Segmented Efficient Laser Emission for Non-Nuclear Electricity (SELENE) Program. Diffuse laser reflection hazards exist for water cloud surfaces less than 722 m in altitude and ice cloud surfaces less than 850 m in altitude. Specular reflections from ice crystals in cirrus clouds are not probable; however, any specular reflection is a hazard to ground observers. The hazard to the laser operators and any ground observers during heavy fog conditions is of such significant magnitude that the laser should not be operated in fog.

Topologically and geometrically flexible structural units in seven new organically templated uranyl selenates and selenite–selenates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru; Kovrugin, Vadim M.; Tyumentseva, Olga S.

2015-09-15

Single crystals of seven novel uranyl oxysalts of selenium with protonated methylamine molecules, [C{sub 2}H{sub 8}N]{sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (I), [C{sub 2}H{sub 8}N]{sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}(H{sub 2}O)] (II), [C{sub 4}H{sub 15}N{sub 3}][H{sub 3}O]{sub 0.5}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 2.93}(SeO{sub 3}){sub 0.07}(H{sub 2}O)](NO{sub 3}){sub 0.5} (III), [C{sub 2}H{sub 8}N]{sub 3}[H{sub 5}O{sub 2}][(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub 2}(H{sub 2}O){sub 5} (IV), [C{sub 2}H{sub 8}N]{sub 2}[H{sub 3}O][(UO{sub 2}){sub 3}(SeO{sub 4}){sub 4}(HSeO{sub 3})(H{sub 2}O)](H{sub 2}SeO{sub 3}){sub 0.2} (V), [C{sub 4}H{sub 12}N]{sub 3}[H{sub 3}O][(UO{sub 2}){sub 3}(SeO{sub 4}){sub 5}(H{sub 2}O)] (VI), and [C{sub 2}H{sub 8}N]{sub 3}(C{sub 2}H{sub 7}N)[(UO{sub 2}){sub 3}(SeO{sub 4}){submore » 4}(HSeO{sub 3})(H{sub 2}O)] (VII) have been prepared by isothermal evaporation from aqueous solutions. Their crystal structures have been solved by direct methods and their uranyl selenate and selenite–selenate units investigated using black-and-white graphs from the viewpoints of topology of interpolyhedral linkages and isomeric variations. The crystal structure of IV is based upon complex layers with unique topology, which has not been observed previously in uranyl selenates. Investigations of the statistics and local distribution of the U–O{sub br}–Se bond angles demonstrates that shorter angles associate with undulations, whereas larger angles correspond to planar areas of the uranyl selenite layers. - Graphical abstract: Crystal structures of the seven novel Se-contaning uranyl oxysalts that contain protonated organic molecules as interlayer species have been investigated from the viewpoints of topology of interpolyhedral linkages, isomeric variations and flexibility of structural units. - Highlights: • Single crystals of seven novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • The method of orientation matrices was applied to distinguish geometrical isomers. • The flexibility of structural complexes specifies the undulation of layered structural units.« less

Lethal and mutagenic effects of ion beams and γ-rays in Aspergillus oryzae.

PubMed

Toyoshima, Yoshiyuki; Takahashi, Akemi; Tanaka, Hisaki; Watanabe, Jun; Mogi, Yoshinobu; Yamazaki, Tatsuo; Hamada, Ryoko; Iwashita, Kazuhiro; Satoh, Katsuya; Narumi, Issay

2012-12-01

Aspergillus oryzae is a fungus that is used widely in traditional Japanese fermentation industries. In this study, the lethal and mutagenic effects of different linear energy transfer (LET) radiation in freeze-dried conidia of A. oryzae were investigated. The lethal effect, which was evaluated by a 90% lethal dose, was dependent on the LET value of the ionizing radiation. The most lethal ionizing radiation among that tested was (12)C(5+) ion beams with an LET of 121keV/μm. The (12)C(5+) ion beams had a 3.6-times higher lethal effect than low-LET (0.2keV/μm) γ-rays. The mutagenic effect was evaluated by the frequency of selenate resistant mutants. (12)C(6+) ion beams with an LET of 86keV/μm were the most effective in inducing selenate resistance. The mutant frequency following exposure to (12)C(6+) ion beams increased with an increase in dose and reached 3.47×10(-3) at 700Gy. In the dose range from 0 to 700Gy, (12)C(5+) ion beams were the second most effective in inducing selenate resistance, the mutant frequency of which reached a maximum peak (1.67×10(-3)) at 400Gy. To elucidate the characteristics of mutation induced by ionizing radiation, mutations in the sulphate permease gene (sB) and ATP sulfurylase gene (sC) loci, the loss of function of which results in a selenate resistant phenotype, were compared between (12)C(5+) ion beams and γ-rays. We detected all types of transversions and transitions. For frameshifts, the frequency of a +1 frameshift was the highest in all cases. Although the incidence of deletions >2bp was generally low, deletions >20bp were characteristic for (12)C(5+) ion beams. γ-rays had a tendency to generate mutants carrying a multitude of mutations in the same locus. Both forms of radiation also induced genome-wide large-scale mutations including chromosome rearrangements and large deletions. These results provide new basic insights into the mutation breeding of A. oryzae using ionizing radiation. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Correlative Cryo-Tem Cryo-Stxm and Cryo-Shxm Investigation of Selenium Bioreduction in a Contaminated Aquifer

NASA Astrophysics Data System (ADS)

Fakra, S.; Luef, B.; Tyliszczak, T.; Castelle, C. J.; Mullin, S. W.; Hug, L. A.; Williams, K. H.; Marcus, M.; Banfield, J. F.

2015-12-01

Accurate mapping of the composition and ultrastructure of minerals and cells is key to understanding biogeochemical process in contaminated environments. Here we developed two apparatus that allow correlation of cryogenic transmission electron microscopy (TEM), synchrotron hard X-ray microprobe (SHXM) and scanning transmission X-ray microscopy (STXM) datasets. These cryogenic methods enabled precise determination of the distribution, valence state and structure of selenium in intact biofilms sampled during a biostimulation experiment in a contaminated aquifer near Rifle, CO, USA. Results were replicated in the laboratory via anaerobic selenate-reducing enrichment cultures. 16S rRNA analyses of field-derived biofilm indicated the dominance of Betaproteobacteria from the Comamonadaceae family, and uncultivated members of the Simplicispira genus. The major product in field and culture-derived biofilms consists of ~25-300 nm red amorphous Se0 aggregates of colloidal nanoparticles. Correlative analyses of the cultures provided direct evidence for microbial dissimilatory reduction of Se(VI) to Se(IV) to Se0. X-ray diffraction and Se K-edge extended X-ray absorption fine structure spectroscopy revealed red amorphous Se0 with a first shell Se-Se interatomic distance of 2.339 ± 0.003 Å. STXM showed that these aggregates are strongly associated with a protein-rich biofilm matrix containing acidic polysaccharides. From Rifle groundwater, we isolated a strain that shares 98.9% 16S rRNA gene sequence identity with Dechloromonas aromatica RCB and grows anaerobically by oxidizing acetate and reducing selenate. We refer to this isolate as Dechloromonas selenatis strain RGW99. 3D cryo-electron tomography showed that Se0 particles do not form inside the cytoplasm but rather originate in the cell membrane. The end product of selenate reduction by D. selenatis is 240 ± 66 nm diameter red amorphous Se0 colloidal aggregates. This product was found to be stable for months. Overall, these results established a role for D. selenatis RGW99 in selenate reduction in the Rifle aquifer and provided new insights into the nature and stability of selenium bioreduction products in the subsurface.

First optical observation of the Moon's sodium exosphere from the lunar orbiter SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Kagitani, M.; Taguchi, M.; Yamazaki, A.; Yoshikawa, I.; Murakami, G.; Yoshioka, K.; Kameda, S.; Ezawa, F.; Toyota, T.; Okano, S.

2009-08-01

The first successful observations of resonant scattering emission from the lunar sodium exosphere were made from the lunar orbiter SELENE (Kaguya) using TVIS instruments during the period 17-19 December, 2008. The emission intensity of the NaD-line decreased by 12±6%, with an average value of 5.4 kR (kilorayleighs) in this period, which was preceded, by 1 day, by enhancement of the solar proton flux associated with a corotating interaction region. The results suggest that solar wind particles foster the diffusion of sodium atoms or ions in the lunar regolith up to the surface and that the time scale of the diffusion is a few tens of hours. The declining activity of the Geminid meteor shower is also one possible explanation for the decreasing sodium exosphere.

Extraordinarily High Leaf Selenium to Sulfur Ratios Define ‘Se-accumulator’ Plants

PubMed Central

White, Philip J.; Bowen, Helen C.; Marshall, Bruce; Broadley, Martin R.

2007-01-01

Background and Aims Selenium (Se) and sulfur (S) exhibit similar chemical properties. In flowering plants (angiosperms) selenate and sulfate are acquired and assimilated by common transport and metabolic pathways. It is hypothesized that most angiosperm species show little or no discrimination in the accumulation of Se and S in leaves when their roots are supplied a mixture of selenate and sulfate, but some, termed Se-accumulator plants, selectively accumulate Se in preference to S under these conditions. Methods This paper surveys Se and S accumulation in leaves of 39 angiosperm species, chosen to represent the range of plant Se accumulation phenotypes, grown hydroponically under identical conditions. Results The data show that, when supplied a mixture of selenate and sulfate: (1) plant species differ in both their leaf Se ([Se]leaf) and leaf S ([S]leaf) concentrations; (2) most angiosperms show little discrimination for the accumulation of Se and S in their leaves and, in non-accumulator plants, [Se]leaf and [S]leaf are highly correlated; (3) [Se]leaf in Se-accumulator plants is significantly greater than in other angiosperms, but [S]leaf, although high, is within the range expected for angiosperms in general; and (4) the Se/S quotient in leaves of Se-accumulator plants is significantly higher than in leaves of other angiosperms. Conclusion The traits of extraordinarily high [Se]leaf and leaf Se/S quotients define the distinct elemental composition of Se-accumulator plants. PMID:17525099

Toxicity of inorganic contaminants, individually and in environmental mixtures, to three endangered fishes (Colorado squawfish, bonytail, and razorback sucker)

USGS Publications Warehouse

Buhl, Kevin J.; Hamilton, S.J.

1996-01-01

Two life stages of three federally-listed endangered fishes, Colorado squawfish (Ptychocheilus lucius), bonytail (Gila elegans), and razorback sucker (Xyrauchen texanus) were exposed to copper, selenate, selenite, and zinc individually, and to mixtures of nine inorganics in a reconstituted water that simulated the water quality of the middle Green River, Utah. The mixtures simulated environmental ratios of arsenate, boron, copper, molybdenum, selenate, selenite, uranium, vanadium, and zinc in two tributaries, Ashley Creek and Stewart Lake outlet, of the middle Green River. The rank order of toxicity of the individual inorganics, from most to least toxic, was: copper > zinc > selenite > selenate. Colorado squawfish larvae were more sensitive to all four inorganics and the two mixtures than the juveniles, whereas there was no consistent response between the two life stages for the other two species. There was no consistent difference in sensitivity to the inorganics among the three endangered fishes. Both mixtures exhibited either additive or greater than additive toxicity to these fishes. The primary toxic components in the mixtures, based on toxic units, were copper and zinc. Acute toxicity values were compared to measured environmental concentrations in the two tributaries to derive margins of uncertainty. Margins of uncertainty were low for both mixtures (9–22 for the Stewart Lake outlet mixture, and 12–32 for the Ashley Creek mixture), indicating that mixtures of inorganics derived from irrigation activities may pose a hazard to endangered fishes in the Green River.

Selenium speciation in acidic environmental samples: application to acid rain-soil interaction at Mount Etna volcano.

PubMed

Floor, Geerke H; Iglesías, Mònica; Román-Ross, Gabriela; Corvini, Philippe F X; Lenz, Markus

2011-09-01

Speciation plays a crucial role in elemental mobility. However, trace level selenium (Se) speciation analyses in aqueous samples from acidic environments are hampered due to adsorption of the analytes (i.e. selenate, selenite) on precipitates. Such solid phases can form during pH adaptation up till now necessary for chromatographic separation. Thermodynamic calculations in this study predicted that a pH<4 is needed to prevent precipitation of Al and Fe phases. Therefore, a speciation method with a low pH eluent that matches the natural sample pH of acid rain-soil interaction samples from Etna volcano was developed. With a mobile phase containing 20mM ammonium citrate at pH 3, selenate and selenite could be separated in different acidic media (spiked water, rain, soil leachates) in <10 min with a LOQ of 0.2 μg L(-1) using (78)Se for detection. Applying this speciation analysis to study acid rain-soil interaction using synthetic rain based on H(2)SO(4) and soil samples collected at the flanks of Etna volcano demonstrated the dominance of selenate over selenite in leachates from samples collected close to the volcanic craters. This suggests that competitive behavior with sulfate present in acid rain might be a key factor in Se mobilization. The developed speciation method can significantly contribute to understand Se cycling in acidic, Al/Fe rich environments. Copyright © 2011 Elsevier Ltd. All rights reserved.

Selenium adsorption and speciation with Mg-FeCO₃ layered double hydroxides loaded cellulose fibre.

PubMed

Chen, Ming-Li; An, Myog-Il

2012-06-15

A novel adsorbent was developed by coating Mg-FeCO(3) layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO(3) LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 μ L of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L(-1) HCl at 80°C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L(-1) within a linear range of 0.04-4.0 μg L(-1). A relative standard deviation (RSD) of 3.3% (0.5 μg L(-1), n=11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Interactions of selenium hyperaccumulators and nonaccumulators during cocultivation on seleniferous or nonseleniferous soil--the importance of having good neighbors.

PubMed

Mehdawi, Ali F El; Cappa, Jennifer J; Fakra, Sirine C; Self, James; Pilon-Smits, Elizabeth A H

2012-04-01

• This study investigated how selenium (Se) affects relationships between Se hyperaccumulator and nonaccumulator species, particularly how plants influence their neighbors' Se accumulation and growth. • Hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and nonaccumulators Astragalus drummondii and Stanleya elata were cocultivated on seleniferous or nonseleniferous soil, or on gravel supplied with different selenate concentrations. The plants were analyzed for growth, Se accumulation and Se speciation. Also, root exudates were analyzed for Se concentration. • The hyperaccumulators showed 2.5-fold better growth on seleniferous than on nonseleniferous soil, and up to fourfold better growth with increasing Se supply; the nonaccumulators showed the opposite results. Both hyperaccumulators and nonaccumulators could affect growth (up to threefold) and Se accumulation (up to sixfold) of neighboring plants. Nonaccumulators S. elata and A. drummondii accumulated predominantly (88-95%) organic C-Se-C; the remainder was selenate. S. elata accumulated relatively more C-Se-C and less selenate when growing adjacent to S. pinnata. Both hyperaccumulators released selenocompounds from their roots. A. bisulcatus exudate contained predominantly C-Se-C compounds; no speciation data could be obtained for S. pinnata. • Thus, plants can affect Se accumulation in neighbors, and soil Se affects competition and facilitation between plants. This helps to explain why hyperaccumulators are found predominantly on seleniferous soils. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

Synthesis of perbromates

NASA Technical Reports Server (NTRS)

Appelman, E. H.; Studier, M. H.

1969-01-01

Salts of heptavalent bromine were synthesized by a hot atom process, the beta decay of radioactive selenium-83 incorporated into a selenate. Formation of an unreactive perbromate ion led to preparation of macro amounts of perborate. A rubidium salt was isolated.

Solution-Processed Cu2ZnSn(S,Se) 4 Thin-Film Solar Cells Using Elemental Cu, Zn, Sn, S, and Se Powders as Source.

PubMed

Guo, Jing; Pei, Yingli; Zhou, Zhengji; Zhou, Wenhui; Kou, Dongxing; Wu, Sixin

2015-12-01

Solution-processed approach for the deposition of Cu2ZnSn (S,Se)4 (CZTSSe) absorbing layer offers a route for fabricating thin film solar cell that is appealing because of simplified and low-cost manufacturing, large-area coverage, and better compatibility with flexible substrates. In this work, we present a simple solution-based approach for simultaneously dissolving the low-cost elemental Cu, Zn, Sn, S, and Se powder, forming a homogeneous CZTSSe precursor solution in a short time. Dense and compact kesterite CZTSSe thin film with high crystallinity and uniform composition was obtained by selenizing the low-temperature annealed spin-coated precursor film. Standard CZTSSe thin film solar cell based on the selenized CZTSSe thin film was fabricated and an efficiency of 6.4 % was achieved.

Separation of selenium species released from Se-exposed algae

USGS Publications Warehouse

Besser, John M.; Huckins, James N.; Clark, Randal C.

1994-01-01

We have assessed a fractionation scheme for selenium species that separates Se-containing amino acids and other organoselenium compounds in aqueous samples. We investigated the retention of standard solutions of selenate (Se+6), selenite (Se+4), and selenomethionine (Se−2) by fractionation media (Sephadex A-25 ion-exchange resin, copper-treated Chelex-100 ligand-exchange resin, and activated charcoal) and by several types of membrane filters. The fractionation method successfully isolated Se from the standard solutions into appropriate fractions for radiometric quantitation of 75Se. However, some filter media retained unacceptably large amounts of selenate and selenite. Mass balance microcosms were inoculated with green algae (Chlamydomonas">Chlamydomonasreinhardtii">reinhardtii) previously exposed to inorganic 75Se, and the fractionation scheme was used to examine the release of 75Se species into water and air. The results of the microcosm exposure indicate that seasonal blooms and crashes of phytoplankton populations may produce increased concentrations of organoselenium species.

Radio Navigation Beacons on the Moon, Lunar Geodetic VLBI System, Physical Libration of the Moon for Chang'E-3/4, Luna-Glob, Luna-Resource and SELENE-2 Projects

NASA Astrophysics Data System (ADS)

Gusev, Alexander; Ping, Jinsong; Hanada, Hideo; Kikuchi, Fuyuhiko; Kosov, Alexander; Li, Jinling; Titov, Oleg

2014-12-01

The future lunar missions of Chang'E-3/4, Luna-Glob, Luna-Resource, and SELENE-2 will consist of a lander and an orbiter. Using the Lunar Same Beam, Differential and Inverse VLBI technologies, we anticipate to determine the coordinates of the radio beacons on the lunar surface with an accuracy of 1 mm for various space projects on the Moon. Small radio telescopes being installed on the surface of the Moon and incorporated into the existing network will help to improve the traditional IVS products by a factor of ten or even more. The model of the two-layer Moon gives several normal rotational modes--Chandler Wobble and Free Core Nutation. They can play an important role in the determination of the core parameters.

Magnetic Cleanliness Program Under Control of Electromagnetic Compatibility for the SELENE (Kaguya) Spacecraft

NASA Astrophysics Data System (ADS)

Matsushima, Masaki; Tsunakawa, Hideo; Iijima, Yu-Ichi; Nakazawa, Satoru; Matsuoka, Ayako; Ikegami, Shingo; Ishikawa, Tomoaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi; Takahashi, Futoshi

2010-07-01

To achieve the scientific objectives related to the lunar magnetic field measurements in a polar orbit at an altitude of 100 km, strict electromagnetic compatibility (EMC) requirements were applied to all components and subsystems of the SELENE (Kaguya) spacecraft. The magnetic cleanliness program was defined as one of the EMC control procedures, and magnetic tests were carried out for most of the engineering and flight models. The EMC performance of all components was systematically controlled and examined through a series of EMC tests. As a result, the Kaguya spacecraft was made to be very clean, magnetically. Hence reliable scientific data related to the magnetic field around the Moon were obtained by the LMAG (Lunar MAGnetometer) and the PACE (Plasma energy Angle and Composition Experiment) onboard the Kaguya spacecraft. These data have been available for lunar science use since November 2009.

Reduction of biselenites into polyselenides in interlayer space of layered double hydroxides

NASA Astrophysics Data System (ADS)

Kim, Myeong Shin; Lee, Yongju; Park, Yong-Min; Cha, Ji-Hyun; Jung, Duk-Young

2018-06-01

A selenous acid (H2SeO3) precursor was intercalated as biselenite (HSeO3-) ions into the interlayer gallery of carbonated magnesium aluminum layered double hydroxide (MgAl-LDH) in aqueous solution. Reduction reaction of selenous ions by aqueous hydrazine solution produced polyselenide intercalated LDHs which were consecutively exchanged with iodide through redox reaction under iodine vapor. The polyselenide containing LDHs adsorbed iodine vapor spontaneously and triiodide was incorporated in the interlayer space followed by formation of selenium polycrystalline phase. Two dimensional framework of MgAl-LDH is strong enough to resist against the reducing power of hydrazine as well as oxidation condition of iodine. The SEM data demonstrated that the shapes of LDH polycrystalline have little changed after the above redox reactions. The polyselenide and iodide LDH products were analyzed by XRD, Infrared and Raman spectra which strongly suggested the horizontal arrangement of polyselenide and triiodide in gallery space of LDHs.

Crystal structure, vibrational spectra and DFT studies of hydrogen bonded 1,2,4-triazolium hydrogenselenate

NASA Astrophysics Data System (ADS)

Arjunan, V.; Thirunarayanan, S.; Marchewka, M. K.; Mohan, S.

2017-10-01

The new hydrogen bonded molecular complex 1,2,4-triazolium hydrogenselenate (THS) is prepared by the reaction of 1H-1,2,4-triazole and selenic acid. This complex is stabilised by N-H⋯O and C-H⋯O hydrogen bonding and electrostatic attractive forces between 1H and 1,2,4-triazolium cations and hydrogen selenate anions. The XRD studies revealed that intermolecular proton transfer occur from selenic acid to 1H-1,2,4-triazole molecule, results in the formation of 1,2,4-triazolium hydrogenselenate which contains 1,2,4-triazolium cations and hydrogenselenate anions. The molecular structure of THS crystal has also been optimised by using Density Functional Theory (DFT) using B3LYP/cc-pVTZ and B3LYP/6-311++G** methods in order to find the whole characteristics of the molecular complex. The theoretical structural parameters such as bond length, bond angle and dihedral angle determined by DFT methods are well agreed with the XRD parameters. The atomic charges and thermodynamic properties are also calculated and analysed. The energies of frontier molecular orbitals HOMO, LUMO, HOMO-1, LUMO+1 and LUMO-HUMO energy gap are calculated to understand the kinetic stability and chemical reactivity of the molecular complex. The natural bond orbital analysis (NBO) has been performed in order to study the intramolecular bonding interactions and delocalisation of electrons. These intra molecular charge transfer may induce biological activities such as antimicrobials, antiinflammatory, antifungal etc. The complete vibrational assignments of THS have been performed by using FT-IR and FT-Raman spectra.

Microbial Selenite Reduction and the Selenium Biogeochemical Cycle

NASA Astrophysics Data System (ADS)

Stolz, J. F.; Wells, M.

2016-12-01

Selenium is an essential trace element utilized by many species in the three domains of life. In most Bacteria and Archaea, selenium is primarily assimilated to form selenocysteine, the 21st amino acid (Sec). Additionally selenium can be methylated, demethylated, or used as a terminal electron acceptor in dissimilatory selenate or selenite reduction. Although progress has been made on elucidating the synthesis of selenoproteins, less is known of their occurrence, diversity, and functionality, primarily due to poor genome annotation (e.g., failure to recognize UGA as a Sec and not a stop codon) and proteomics analysis (e.g., failure to detect Sec in LC/MS-MS). Furthermore important parts of the selenium biogeochemical cycle remain to be fully explored, in particular the reduction of Se(IV) to Se(O). We have examined the selenoproteome of a selenate respiring bacterium Sulfurospirillum barnesii strain SES-3, which reduces Se(VI) to Se(0) and the dissimilatory selenite reducing bacterium, Bacillus selenitireducens, strain MLS-10, which reduces Se(IV) to Se(0). Candidate selenoproteins including D-proline reductase, formate dehydrogenase, and methionine-S sulfoxide reductase have been identified in the genomes. A putative dissimilatory selenate reducase (Ser) was found in the genome of S. barnesii. More significant was the discovery of a candidate for the respiratory selenite reductase in B. selenitireducens as determined by in gel assays and LC/MS-MS. The latter has provided a hint at the potential diversity of DSiR bacteria and the development of molecular probes for investigating DSiR in the selenium biogeochemical cycle.

Systems analysis on laser beamed power

NASA Technical Reports Server (NTRS)

Zeiders, Glenn W., Jr.

1993-01-01

The NASA SELENE power beaming program is intended to supply cost-effective power to space assets via Earth-based lasers and active optics systems. Key elements of the program are analyzed, the overall effort is reviewed, and recommendations are presented.

Selenium.

PubMed

Barceloux, D G

1999-01-01

The 4 natural oxidation states of selenium are elemental selenium (0), selenide (-2), selenite (+4), and selenate (+6). Inorganic selenate and selenite predominate in water whereas organic selenium compounds (selenomethionine, selenocysteine) are the major selenium species in cereal and in vegetables. The principal applications of selenium include the manufacture of ceramics, glass, photoelectric cells, pigments, rectifiers, semiconductors, and steel as well as use in photography, pharmaceutical production, and rubber vulcanizing. High concentrations of selenium in surface and in ground water usually occur in farm areas where irrigation water drains from soils with high selenium content (Kesterson Reservoir, California) or in lakes receiving condenser cooling water from coal-fired electric power plants (Belews Lake, North Carolina). For the general population, the primary pathway of exposure to selenium is food, followed by water and air. Both selenite and selenate possess substantial bioavailability. However, plants preferentially absorb selenates and convert them to organic compounds. Aquatic organisms (e.g., bivalves) can accumulate and magnify selenium in the food chain. Selenium is an essential component of glutathione peroxidase, which is an important enzyme for processes that protect lipids in polyunsaturated membranes from oxidative degradation. Inadequate concentrations of selenium in the Chinese diet account, at least in part, for the illness called Keshan disease. Selenium deficiency occurs in the geographic areas where Balkan nephropathy appears, but there is no direct evidence that selenium deficiency contributes to the development of this chronic, progressive kidney disease. Several lines of scientific inquiry suggest that an increased risk of cancer occurs as a result of low concentrations of selenium in the diet; however, insufficient evidence exists at the present time to recommend the use of selenium supplements for the prevention of cancer. The toxicity of most forms of selenium is low and the toxicity depends on the chemical form of selenium. The acute ingestion of selenious acid is almost invariably fatal, preceded by stupor, hypotension, and respiratory depression. Chronic selenium poisoning has been reported in China where changes in the hair and nails resulted from excessive environmental exposures to selenium. Garlic odor on the breath is an indication of excessive selenium exposure as a result of the expiration of dimethyl selenide. The US National Toxicology Program lists selenium sulfide as an animal carcinogen, but there is no evidence that other selenium compounds are carcinogens.

Selenium Treatment Technologies

EPA Science Inventory

Selenium (Se) is a metalloid that is a dietary requirement in small quantities, but toxic at higher quantities. It also is known to bioaccumulate. In oxic environments, it exists as selenate (+6) and selenite (+4), both of which are soluble. Selenite will sorb more strongly to...

SPECIATION OF SELENIUM AND ARSENIC COMPOUNDS BY CAPILLARY...

EPA Science Inventory

Capillary electrophoresis (CE) with hydride generation inductively coupled plasma mass spectrometry was used to determine four arsenicals and two selenium species. Selenate (SeVI) was reduced on-line to selenite (SeIV) by mixing the CE effluent with concentrated HCl. A microporou...

BACTERIAL RESPIRATION OF ARSENIC AND SELENIUM. (R826105)

EPA Science Inventory

Abstract

Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichme...

SELENIUM REMOVAL FROM DRINKING WATER BY ION EXCHANGE

EPA Science Inventory

Strong-base anion exchangers were shown to remove selenate and selenite ions from drinking water. Because selenium species are usually present at low concentrations, the efficiency of removal is controlled by the concentration of the common drinking water anions, the most importa...

Hazard evaluation of inorganics, singly and in mixtures, to Flannelmouth Sucker Catostomus latipinnis in the San Juan River, New Mexico

USGS Publications Warehouse

Hamilton, S.J.; Buhl, K.J.

1997-01-01

Larval flannelmouth sucker (Catostomus latipinnis) were exposed to arsenate, boron, copper, molybdenum, selenate, selenite, uranium, vanadium, and zinc singly, and to five mixtures of five to nine inorganics. The exposures were conducted in reconstituted water representative of the San Juan River near Shiprock, New Mexico. The mixtures simulated environmental ratios reported for sites along the San Juan River (San Juan River backwater, Fruitland marsh, Hogback East Drain, Mancos River, and McElmo Creek). The rank order of the individual inorganics, from most to least toxic, was: copper > zinc > vanadium > selenite > selenate > arsenate > uranium > boron > molybdenum. All five mixtures exhibited additive toxicity to flannelmouth sucker. In a limited number of tests, 44-day-old and 13-day-old larvae exhibited no difference in sensitivity to three mixtures. Copper was the major toxic component in four mixtures (San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek), whereas zinc was the major toxic component in the Fruitland marsh mixture, which did not contain copper. The Hogback East Drain was the most toxic mixture tested. Comparison of 96-h LC50values with reported environmental water concentrations from the San Juan River revealed low hazard ratios for arsenic, boron, molybdenum, selenate, selenite, uranium, and vanadium, moderate hazard ratios for zinc and the Fruitland marsh mixture, and high hazard ratios for copper at three sites and four environmental mixtures representing a San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek. The high hazard ratios suggest that inorganic contaminants could adversely affect larval flannelmouth sucker in the San Juan River at four sites receiving elevated inorganics.

Amelioration of CCl4-induced liver injury in rats by selenizing Astragalus polysaccharides: Role of proinflammatory cytokines, oxidative stress and hepatic stellate cells.

PubMed

Hamid, Mohammed; Liu, Dandan; Abdulrahim, Yassin; Liu, Yunhuan; Qian, Gang; Khan, Alamzeb; Gan, Fang; Huang, Kehe

2017-10-01

Selenizing Astragalus polysaccharides (sAPS) were prepared by nitric acid-sodium selenite method. Effect of sAPS on carbon tetrachloride (CCl4)-induced liver injury and the underlying mechanisms were investigated in the rat. Forty male Wistar rats were divided into five equal groups as follows: control group; CCl 4 group; CCl 4 +Astragalus polysaccharides group; CCl 4 +sodium selenite group and CCl 4 +selenizing Astragalus polysaccharides group. The results showed that sAPS significantly decreased the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase in the serum, malondialdehyde and hydroxyproline content in liver (P<0.01), and increased the levels of total protein, total antioxidant capacity, glutathione peroxidase, and superoxide dismutase in liver of rats induced by CCl 4. In addition, expression levels of antioxidant-related genes (GPX1, SOD1, and Nrf2) were significantly increased following supplementation of the sAPS (P<0.01). Furthermore, sAPS effectively ameliorated CCl 4 induced hepatic necrosis and inflammation, and it also reduced the expression levels of proinflammatory cytokines including TNF-α, IL-6, COX-2 and NFκB (P<0.01) . Moreover, sAPS significantly decreased the expression levels of α-smooth muscle actin, collagen 1, TGF-β1, but increased the Bcl-2/Bax mRNA ratio in rats administered CCl 4 (P<0.01). Taken together, it could be concluded that sAPS could increase the activities of Astragalus polysaccharides and sodium selenite to protect the liver from damage by attenuating hepatic inflammation, oxidative stress, fibrogenesis, and induces apoptosis and cell cycle arrest in hepatic stellate cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Pb2F2](SeO4): a heavier analogue of grandreefite, the first layered fluoride selenate

NASA Astrophysics Data System (ADS)

Charkin, Dmitri O.; Plokhikh, Igor V.; Zadoya, Anastasiya I.; Kazakov, Sergey M.; Zaloga, Alexander N.; Kozin, Michael S.; Depmeier, Wulf; Siidra, Oleg I.

2018-01-01

Co-precipitation of PbF2 and PbSeO4 in weakly acidic media results in the formation of [Pb2F2](SeO4), the selenate analogue of the naturally occurring mineral grandreefite, [Pb2F2](SO4). The new compound is monoclinic, C2/ c, a = 14.0784(2) Å, b = 4.6267(1) Å, c = 8.8628(1) Å, β = 108.98(1)°, V = 545.93(1) Å3. Its structure has been refined from powder data to R B = 1.55%. From thermal studies, it is established that the compound is stable in air up to about 300 °C, after which it gradually converts into a single phase with composition [Pb2O](SeO4), space group C2/ m, and lattice parameters a = 14.0332(1) Å, b = 5.7532(1) Å, c = 7.2113(1) Å, β = 115.07(1)°, V = 527.37(1) Å3. It is the selenate analogue of lanarkite, [Pb2O](SO4), and phoenicochroite, [Pb2O](CrO4), and its crystal structure was refined to R B = 1.21%. The formation of a single decomposition product upon heating in air suggests that this happens by a thermal hydrolysis mechanism, i.e., Pb2F2SeO4 + H2O (vapor) → Pb2OSeO4 + 2HF↑. This relatively low-temperature process involves complete rearrangement of the crystal structure—from a 2D architecture featuring slabs [Pb2F2]2+ formed by fluorine-centered tetrahedra into a structure characterized by 1D motifs based on [OPb2]2+ chains of oxocentered tetrahedra. The comparative crystal chemistry of the obtained anion-centered structural architectures is discussed.

Chiral speciation and determination of selenomethionine enantiomers in selenized yeast by ligand-exchange micellar electrokinetic capillary chromatography after solid phase extraction.

PubMed

Duan, Jiankun; He, Man; Hu, Bin

2012-12-14

A new phenylalanine derivative (L-N-(2-hydroxy-propyl)-phenylalanine, L-HP-Phe) was synthesized and its chelate with Cu(II) (Cu(II)-(L-HP-Phe)(2)) was used as the chiral selector for the ligand-exchange (LE) chiral separation of D,L-selenomethionine (SeMet) in selenized yeast samples by micelle electrokinetic capillary chromatography (MEKC). In order to improve the sensitivity of MEKC-UV, two-step preconcentration strategy was employed, off-line solid phase extraction (SPE) and on-line large volume sample stacking (LVSS). D,L-SeMet was first retained on the Cu(II) loaded mesoporous TiO(2), then eluted by 0.1 mL of 5 mol L(-1) ammonia, and finally introduced for MEKC-UV analysis by LVSS injection after evaporation of NH(3). With the enrichment factors of 1400 and 1378, the LODs of 0.44 and 0.60 ng mL(-1) for L-SeMet and D-SeMet was obtained, respectively. The developed method was applied to the analysis of D,L-SeMet in a certified reference material of SELM-1 and a commercial nutrition yeast, and the results showed that most of SeMet in the SELM-1 selenized yeast was l isomer and the recovery for L and D isomers in the spiked commercial nutrition yeast was 96.3% and 103%, respectively. This method is featured with low running cost, high sensitivity and selectivity, and exhibits application potential in chiral analysis of seleno amino acids in real world samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Probing the Influence of Acidity and Temperature to Th(IV) on Hydrolysis, Nucleation, and Structural Topology.

PubMed

Lin, Jian; Qie, Meiying; Zhang, Linjuan; Wang, Xiaomei; Lin, Yuejian; Liu, Wei; Bao, Hongliang; Wang, Jianqiang

2017-11-20

Systematic control of the molar ratio between thorium hydroxides and selenic acid and their reaction temperature under hydrothermal conditions results in four novel thorium-based selenate complexes, namely, [Th 8 O 4 (OH) 8 (SeO 4 ) 6 (H 2 O) 16 ]·(SeO 4 ) 2 ·13H 2 O (Th-1), [Th 8 O 4 (OH) 8 (SeO 4 ) 8 (H 2 O) 13 ]·7H 2 O (Th-2), Th(OH) 2 (SeO 4 )H 2 O (Th-3), and Th 3 (SeO 4 ) 6 (H 2 O) 6 ·2.5H 2 O (Th-4), as well as the thorium mixed selenite selenate compound Th(SeO 3 )(SeO 4 ) (Th-5). Smaller [H 2 SeO 4 ]/[Th(IV)] ratio or lower temperature give rise to the formation of octameric [Th 8 (μ 3 -O) 4 (μ 2 -OH) 8 ] 16+ cores in Th-1/Th-2 and infinite [Th(μ 2 -OH) 2 H 2 O] 2+ chains in Th-3, respectively. Increasing the [H 2 SeO 4 ]/[Th(IV)] ratio or elevating the temperature generates a microporous (11.3 Å voids) open-framework Th-4, a monomeric thorium species without oxo/hydroxyl ligands, and a three-dimensional thorium structure Th-5. Formation of these compounds suggests that variables including acidity and temperature play a critical role in the hydrolysis and oligomerization of Th IV ions. Increasing acidity limits the deprotonation of water molecules and formation of nucleophilic hydroxo/oxo-aquo Th species, and high temperature appears to suppress the olation/oxolation hydrolysis reactions, which in both ways limit the formation of the thorium oligomers.

Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill samples from the Powder River basin, Wyoming

USGS Publications Warehouse

See, R.B.; Reddy, K.J.; Vance, G.F.; Fadlelmawla, A.A.; Blaylock, M.J.

1995-01-01

Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill aquifers were investigated. Backfill and ground-water samples were collected at coal mines in the Powder River Basin, Wyoming. Backfill was generally dominated by aluminum (14,400 to 49,000 mg/kg (milligrams per kilogram)), iron (3,330 to 23,200 mg/kg), and potassium (7,950 to 18,000 mg/kg). Backfill saturated-paste selenium concentrations ranged from 1 to 156 mg/kg (microsiemens per kilogram). Ground-water total selenium concentrations ranged from 3 to 125 mg/L. Dissolved organic carbon in all ground-water samples was dominated by hydrophobic and hydrophilic acids (38 to 84 percent). Selenite sorption/desorption experiments were conducted using background solutions of distilled-deionized water, 0.1 molar calcium chloride, and isolated hydrophobic and hydrophilic acids. Selenite sorption was larger when 0.1 molar calcium chloride was used. The addition of hydrophilic acid decreased selenite sorption more than the addition of hydrophobic acids. Geochemical modelling was used to predict the solid phases controlling dissolved selenium concentrations and to evaluate the effects of dissolved organic carbon on selenium solubility. Results suggested that 55 to 90 percent of selenium in backfill precipitation/dissolution extracts was dominated by magnesium selenate ion pairs. Dissolved organic carbon had little effect on selenium speciation. A redox chamber was constructed to control Eh and pH in water and backfill-core sample suspensions. The response of selenite and selenate in water samples to redox conditions did not follow thermodynamic predictions. Reduction of selenate in water samples did not occur at any of the redox levels tested.

Rover exploration on the lunar surface; a science proposal for SELENE-B mission

NASA Astrophysics Data System (ADS)

Sasaki, S.; Kubota, T.; Akiyama, H.; Hirata, N.; Kunii, Y.; Matsumoto, K.; Okada, T.; Otake, M.; Saiki, K.; Sugihara, T.

LUNARSURFACE:ASCIENCES. Sasaki (1), T. Kubota (2) , H. Akiyama (1) , N. Hirata (3), Y. Kunii (4), K. Matsumoto (5), T. Okada (2), M. Otake (3), K. Saiki (6), T. Sugihara (3) (1) Department of Earth and Planetary Science, Univ. Tokyo, (2) Institute of Space and Astronautical Sciences, (3) National Space Development Agency of Japan, (4) Department of Electrical and Electronic Engineering, Chuo Univ., (5) National Aerospace Laboratory of Japan, (6) Research Institute of Materials and Resources, Akita Univ. sho@eps.s.u -tokyo.ac.jp/Fax:+81-3-5841-4569 A new lunar landing mission (SELENE-B) is now in consideration in Japan. Scientific investigation plans using a rover are proposed. To clarify the origin and evolution of the moon, the early crustal formation and later mare volcanic processes are still unveiled. We proposed two geological investigation plans: exploration of a crater central peak to discover subsurface materials and exploration of dome-cone structures on young mare region. We propose multi-band macro/micro camera using AOTF, X-ray spectrometer/diffractometer and gamma ray spectrometer. Since observation of rock fragments in brecciaed rocks is necessary, the rover should have cutting or scraping mechanism of rocks. In our current scenario, landing should be performed about 500m from the main target (foot of a crater central peak or a cone/dome). After the spectral survey by multi-band camera on the lander, the rover should be deployed for geological investigation. The rover should make a short (a few tens meter) round trip at first, then it should perform traverse observation toward the main target. Some technological investigations on SELENE-B project will be also presented.

Bioaccessibility of selenium after human ingestion in relation to its chemical species and compartmentalization in maize.

PubMed

Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Laplanche, Christophe; Pierart, Antoine; Longchamp, Mélanie; Besson, Philippe; Castrec-Rouelle, Maryse

2016-06-01

Selenium is a micronutrient needed by all living organisms including humans, but often present in low concentration in food with possible deficiency. From another side, at higher concentrations in soils as observed in seleniferous regions of the world, and in function of its chemical species, Se can also induce (eco)toxicity. Root Se uptake was therefore studied in function of its initial form for maize (Zea mays L.), a plant widely cultivated for human and animal food over the world. Se phytotoxicity and compartmentalization were studied in different aerial plant tissues. For the first time, Se oral human bioaccessibility after ingestion was assessed for the main Se species (Se(IV) and Se(VI)) with the BARGE ex vivo test in maize seeds (consumed by humans), and in stems and leaves consumed by animals. Corn seedlings were cultivated in hydroponic conditions supplemented with 1 mg L(-1) of selenium (Se(IV), Se(VI), Control) for 4 months. Biomass, Se concentration, and bioaccessibility were measured on harvested plants. A reduction in plant biomass was observed under Se treatments compared to control, suggesting its phytotoxicity. This plant biomass reduction was higher for selenite species than selenate, and seed was the main affected compartment compared to control. Selenium compartmentalization study showed that for selenate species, a preferential accumulation was observed in leaves, whereas selenite translocation was very limited toward maize aerial parts, except in the seeds where selenite concentrations are generally high. Selenium oral bioaccessibility after ingestion fluctuated from 49 to 89 % according to the considered plant tissue and Se species. Whatever the tissue, selenate appeared as the most human bioaccessible form. A potential Se toxicity was highlighted for people living in seleniferous regions, this risk being enhanced by the high Se bioaccessibility.

Characterisation of 1,3-diammonium propylselenate monohydrate by XRD, FT-IR, FT-Raman, DSC and DFT studies

NASA Astrophysics Data System (ADS)

Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.; Atalay, Yusuf

2016-03-01

The crystals of 1,3-diammonium propylselenate monohydrate (DAPS) were prepared and characterised X-ray diffraction (XRD), FT-IR, FT-Raman spectroscopy, and DFT/B3LYP methods. It comprises protonated propyl ammonium moieties (diammonium propyl cations), selenate anions and water molecule which are held together by a number of hydrogen bonds and form infinite chains. The XRD data confirm the transfer of two protons from selenic acid to 1,3-diaminopropane molecule. The DAPS complex is stabilised by the presence of O-H···O and N-H···O hydrogen bonds and the electrostatic interactions as well. The N···O and O···O bond distances are 2.82-2.91 and 2.77 Å, respectively. The FT-IR and FT-Raman spectra of 1,3-diammonium propyl selenate monohydrate are recorded and the complete vibrational assignments have been discussed. The geometry is optimised by B3LYP method using 6-311G, 6-311+G and 6-311+G* basis sets and the energy, structural parameters, vibrational frequencies, IR and Raman intensities are determined. Differential scanning colorimetry (DSC) data were also presented to analyse the possibility of the phase transition. Complete natural bonding orbital (NBO) analysis is carried out to analyse the intramolecular electronic interactions and their stabilisation energies. The electrostatic potential of the complex lies in the range +1.902e × 10-2 to -1.902e × 10-2. The limits of total electron density of the complex is +8.43e × 10-2 to -8.43e × 10-2.

Selenium Adsorption To Aluminum-Based Water Treatment Residuals

EPA Science Inventory

Aluminum-based water treatment residuals (WTR) can adsorb water-and soil-borne P, As(V), As(III), and perchlorate, and may be able to adsorb excess environmental selenium. WTR, clay minerals, and amorphous aluminum hydroxide were shaken for 24 hours in selenate or selenite solut...

21 CFR 573.920 - Selenium.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... Act; unless the Commissioner of Food and Drugs makes a determination that: (1) Selenium additives are... food additive selenium is a nutrient administered in animal feed as sodium selenite or sodium selenate...

21 CFR 573.920 - Selenium.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... Act; unless the Commissioner of Food and Drugs makes a determination that: (1) Selenium additives are... food additive selenium is a nutrient administered in animal feed as sodium selenite or sodium selenate...

21 CFR 573.920 - Selenium.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... Act; unless the Commissioner of Food and Drugs makes a determination that: (1) Selenium additives are... food additive selenium is a nutrient administered in animal feed as sodium selenite or sodium selenate...

21 CFR 573.920 - Selenium.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... Act; unless the Commissioner of Food and Drugs makes a determination that: (1) Selenium additives are... food additive selenium is a nutrient administered in animal feed as sodium selenite or sodium selenate...

21 CFR 573.920 - Selenium.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... Act; unless the Commissioner of Food and Drugs makes a determination that: (1) Selenium additives are... food additive selenium is a nutrient administered in animal feed as sodium selenite or sodium selenate...

Carbon- and oxygen-free Cu(InGa)(SSe)₂ solar cell with a 4.63% conversion efficiency by electrostatic spray deposition.

PubMed

Yoon, Hyun; Na, Seung Heon; Choi, Jae Young; Kim, Min Woo; Kim, Hayong; An, Hee Sang; Min, Byoung Koun; Ahn, SeJin; Yun, Jae Ho; Gwak, Jihye; Yoon, KyungHoon; Kolekar, Sanjay S; van Hest, Maikel F A M; Al-Deyab, Salem S; Swihart, Mark T; Yoon, Sam S

2014-06-11

We have demonstrated the first example of carbon- and oxygen-free Cu(In,Ga)(SSe)2 (CIGSSe) absorber layers prepared by electrospraying a CuInGa (CIG) precursor followed by annealing, sulfurization, and selenization at elevated temperature. X-ray diffraction and scanning electron microscopy showed that the amorphous as-deposited (CIG) precursor film was converted into polycrystalline CIGSSe with a flat-grained morphology after post-treatment. The optimal post-treatment temperature was 300 °C for annealing and 500 °C for both sulfurization and selenization, with a ramp rate of 5 °C/min. The carbon impurities in the precursor film were removed by air annealing, and oxide that was formed during annealing was removed by sulfurization. The fabricated CIGSSe solar cell showed a conversion efficiency of 4.63% for a 0.44 cm(2) area, with Voc = 0.4 V, Jsc = 21 mA/cm(2), and FF = 0.53.

Some physical investigations on ZnS 1- xSe x films obtained by selenization of ZnS sprayed films using the Boubaker polynomials expansion scheme

NASA Astrophysics Data System (ADS)

Fridjine, S.; Touihri, S.; Boubaker, K.; Amlouk, M.

2010-01-01

ZnS 1- xSe x thin films have been grown by selenization process, applied to ZnS sprayed thin films deposited on Pyrex glass substrates at 550 °C. The crystal structure and surface morphology were investigated by the XRD technique and by the atomic force microscopy. This structural study shows that selenium-free ( x=0) ZnS thin films, prepared at substrate temperature TS=450 °C, were well crystallized in cubic structure and oriented preferentially along (1 1 1) direction. The thermal and mechanical properties were also investigated using a photothermal protocol along with Vickers hardness measurements. On the other hand, the analyze of the transmittance T( λ) and the reflectance R( λ), optical measurements of these films depicts a decrease in the band gap energy value Eg with an increase in Se content ( x). Indeed, Eg values vary from 3.6 to 3.1 eV.

Detection of Intact Lava Tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder

NASA Astrophysics Data System (ADS)

Kaku, T.; Haruyama, J.; Miyake, W.; Kumamoto, A.; Ishiyama, K.; Nishibori, T.; Yamamoto, K.; Crites, Sarah T.; Michikami, T.; Yokota, Y.; Sood, R.; Melosh, H. J.; Chappaz, L.; Howell, K. C.

2017-10-01

Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon's composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00-15.00°N, 301.85-304.01°E around the MHH, and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.

Monolayer PtSe₂, a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt.

PubMed

Wang, Yeliang; Li, Linfei; Yao, Wei; Song, Shiru; Sun, J T; Pan, Jinbo; Ren, Xiao; Li, Chen; Okunishi, Eiji; Wang, Yu-Qi; Wang, Eryin; Shao, Yan; Zhang, Y Y; Yang, Hai-tao; Schwier, Eike F; Iwasawa, Hideaki; Shimada, Kenya; Taniguchi, Masaki; Cheng, Zhaohua; Zhou, Shuyun; Du, Shixuan; Pennycook, Stephen J; Pantelides, Sokrates T; Gao, Hong-Jun

2015-06-10

Single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. A combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrast to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.

Massively parallel algorithms for real-time wavefront control of a dense adaptive optics system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fijany, A.; Milman, M.; Redding, D.

1994-12-31

In this paper massively parallel algorithms and architectures for real-time wavefront control of a dense adaptive optic system (SELENE) are presented. The authors have already shown that the computation of a near optimal control algorithm for SELENE can be reduced to the solution of a discrete Poisson equation on a regular domain. Although, this represents an optimal computation, due the large size of the system and the high sampling rate requirement, the implementation of this control algorithm poses a computationally challenging problem since it demands a sustained computational throughput of the order of 10 GFlops. They develop a novel algorithm,more » designated as Fast Invariant Imbedding algorithm, which offers a massive degree of parallelism with simple communication and synchronization requirements. Due to these features, this algorithm is significantly more efficient than other Fast Poisson Solvers for implementation on massively parallel architectures. The authors also discuss two massively parallel, algorithmically specialized, architectures for low-cost and optimal implementation of the Fast Invariant Imbedding algorithm.« less

Semimicrodetermination of combined tantalum and niobium with selenous acid

USGS Publications Warehouse

Grimaldi, F.S.; Schnepfe, M.

1959-01-01

Tantalum and niobium are separated and determined gravimetrically by precipitation with selenous acid from highly acidic solutions in the absence of complexing agents. Hydrogen peroxide is used in the preparation of the solution and later catalytically destroyed during digestion of the precipitate. From 0.2 to 30 mg., separately or in mixtures, of niobium or tantalum pentoxide can be separated from mixtures containing 100 mg. each of the oxides of scandium, yttrium, cerium, vanadium, molybdenum, iron, aluminum, tin, lead, and bismuth with a single precipitation; and from 30 mg. of titanium dioxide, and 50 mg. each of the oxides of antimony and thorium, when present separately, with three precipitations. At least 50 mg. of uranium(VI) oxide can be separated with a single precipitation when present alone; otherwise, three precipitations may be needed. Zirconium does not interfere when the tantalum and niobium contents of the sample are small, but in general, zirconium as well as tungsten interfere. The method is applied to the determination of the earth acids in tantaloniobate ores.

Selenomethionine as a Safer Substitute for Barium Selenate in Long-Acting Injectable Se Supplements for Food-Producing Animals.

PubMed

Knowles, Scott O; Grace, Neville D

2017-09-20

Nutritional supplementation with selenium (Se) can prevent Se deficiency in food-producing animals. Injection with slow-release formulations is a preferred method for free-range grazing sheep and cattle, and barium selenate (BaSeO 4 ) provides optimal efficacy. This chemical can become a health risk to humans if the concentrated depot of an injection site is consumed, and consequently such use is recently banned in the EU. A possible replacement is selenomethionine (SeMet), a naturally occurring form of Se supplementation hitherto only administered orally. In four animal studies we found that injection with SeMet maintained nutritionally adequate concentrations of Se in blood and tissues of lambs for at least 191 days and in blood and milk of dairy cows for at least 95 days. Stereoisomer forms L- and DL-SeMet were functionally equivalent. This is the first demonstration that injectable SeMet can deliver efficacy similar to BaSeO 4 but with less risk of undesirable residues in edible tissues.

Around Marshall

NASA Image and Video Library

1993-03-01

The SELENE Optics project was designed to send powerful laser beams into space to repower satellites and to recharge their batteries, as well as sending laser beams to the moon for the same purpose instead of relying on solar power. This project also was intended to be used for repowering extended space flights.

Influence of the Organic Species and Oxoanion in the Synthesis of two Uranyl Sulfate Hydrates, (H 3 O) 2 [(UO 2 ) 2 (SO 4 ) 3 ­(H 2 O)]·7H 2 O and (H 3 O) 2 [(UO 2 ) 2 (SO 4 ) 3 (H 2 O)]·4H 2 O, and a Uranyl Selenate-Selenite [C 5 H 6 N][(UO 2 )(SeO 4 )(HSeO 3 )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jouffret, Laurent J.; Wylie, Ernest M.; Burns, Peter C.

2012-08-08

Two uranyl sulfate hydrates, (H3O)2[(UO2)2(SO4)3(H2O)]·7H2O (NDUS) and (H3O)2[(UO2)2(SO4)3(H2O)]·4H2O (NDUS1), and one uranyl selenate-selenite [C5H6N][(UO2)(SeO4)(HSeO3)] (NDUSe), were obtained and their crystal structures solved. NDUS and NDUSe result from reactions in highly acidic media in the presence of L-cystine at 373 K. NDUS crystallized in a closed vial at 278 K after 5 days and NDUSe in an open beaker at 278 K after 2 weeks. NDUS1 was synthesized from aqueous solution at room temperature over the course of a month. NDUS, NDUS1, and NDUSe crystallize in the monoclinic space group P21/n, a = 15.0249(4) Å,b = 9.9320(2) Å, c = 15.6518(4)more » Å, β = 112.778(1)°, V = 2153.52(9) Å3,Z = 4, the tetragonal space group P43212, a = 10.6111(2) Å,c = 31.644(1) Å, V = 3563.0(2) Å3, Z = 8, and in the monoclinic space group P21/n, a = 8.993(3) Å, b = 13.399(5) Å, c = 10.640(4) Å,β = 108.230(4)°, V = 1217.7(8) Å3, Z = 4, respectively.The structural units of NDUS and NDUS1 are two-dimensional uranyl sulfate sheets with a U/S ratio of 2/3. The structural unit of NDUSe is a two-dimensional uranyl selenate-selenite sheets with a U/Se ratio of 1/2. In-situ reaction of the L-cystine ligands gives two distinct products for the different acids used here. Where sulfuric acid is used, only H3O+ cations are located in the interlayer space, where they balance the charge of the sheets, whereas where selenic acid is used, interlayer C5H6N+ cations result from the cyclization of the carboxyl groups of L-cystine, balancing the charge of the sheets.« less

Lunar Dust Monitor to BE Onboard the Next Japanese Lunar Mission SELENE-2

NASA Astrophysics Data System (ADS)

Ohashi, Hideo

The next Japanese lunar mission SELENE-2, after a successful mission Kaguya (a project named SELENE), is planned to be launched in mid 2010s and is consisted of a lander, a rover, and an orbiter, as a transmitting satellite to the earth. A dust particle detector LDM (Lunar Dust Monitor) is proposed to be onboard the orbiter. The LDM is an impact ionization detector with dimensions 25 cm × 25 cm × 30 cm, and it has a sensor part (LDM-S, upper module) and an electronics part (LDM-E, lower module). The LDM-S has a large target (gold-plated Al) of 400 cm2 , to which a high voltage of +500 V is applied. The LDM-S also has two meshed grids parallel to the target. The grids are etched stainless steel with 90% transparency: the inner grid is 2 cm apart from the target and the outer grid is 15 cm from the target. When a charged dust particle passes through the outer and inner grids, it induces an electric signal on the grids separated by a certain time interval, determined by the velocity of the incident particle and the distance between the outer and inner grids. By measuring the time interval, we can calculate the velocity of the particle, with the ambiguity of its trajectory to the target. When the incident particle impacts on the target, plasma gas of electrons and ions is generated. The electrons of the plasma are collected by the target and the ions are accelerated toward the inner grids as a result of the electric field. Some of the ions drift through the inner grid and reach the outer grid. The outer and inner grids and the target are connected to charge-sensitive amplifiers, which convert charge signals induced by the electrons and ions to voltage signals that are fed to a following flash ADC driven with 10 MHz. The waveforms from two grids and the target can be stored and be sent back to ground for data analysis. We can deduce the mass and velocity information of the incident dust particle from the recorded waveforms. The orbiter of SELENE-2 is planned to be in operation for one year or more, and the LDM will observe circumlunar dust for as long as possible. We report scientific importance of dust measurement around the Moon, and current status of LDM in this conference.

Comparative oral dose toxicokinetics of selenium compounds commonly found in selenium accumulator plants

USDA-ARS?s Scientific Manuscript database

Consumption of Se accumulator plants by livestock can result in Se intoxication. Recent research indicates that the Se forms most common in Se accumulator plants are selenate and Se-methylselenocysteine (MeSeCys). In this study the absorption, distribution, and elimination kinetics of Se in serum ...

SELENIHALANAEROBACTER SHRIFTII GEN. NOV., SP. NOV., A HALOPHILIC ANAEROBE FROM DEAD SEA SEDIMENTS THAT RESPIRES SELENATE. (R826105)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

‘‘Omics’’ of Selenium Biology: A Prospective Study of Plasma Proteome Network Before and After Selenized-Yeast Supplementation in Healthy Men

USDA-ARS?s Scientific Manuscript database

Low selenium levels have been linked to a higher incidence of cancer and other diseases, including Keshan,Chagas, and Kashin–Beck, and insulin resistance. Additionally, muscle and cardiovascular disorders, immune dysfunction, cancer, neurological disorders, and endocrine function have been associate...

Reduction of Selenite to Elemental Red Selenium by Pseudomonas sp. strain CA5

USDA-ARS?s Scientific Manuscript database

A Pseudomonas sp. that may be useful in bioremediation projects was isolated from soil. The strain is of potential value because it reduces selenite to elemental red selenium and is unusual in that it was resistant to high concentrations of both selenate and selenite. Cell of the strain removed 1....

Biogenic selenium nanoparticles: current status and future prospects.

PubMed

Wadhwani, Sweety A; Shedbalkar, Utkarsha U; Singh, Richa; Chopade, Balu A

2016-03-01

Selenium nanoparticles (SeNPs) are gaining importance in the field of medicine owing to their antibacterial and anticancer properties. SeNPs are biocompatible and non-toxic compared to the counterparts, selenite (SeO3 (-2)) and selenate (SeO4 (-2)). They can be synthesized by physical, chemical, and biological methods and have distinct bright orange-red color. Biogenic SeNPs are stable and do not aggregate owing to natural coating of the biomolecules. Various hypotheses have been proposed to describe the mechanism of microbial synthesis of SeNPs. It is primarily a two-step reduction process from SeO4 (-2) to SeO3 (-2) to insoluble elemental selenium (Se(0)) catalyzed by selenate and selenite reductases. Phenazine-1-carboxylic acid and glutathione are involved in selenite reduction. Se factor A (SefA) and metalloid reductase Rar A present on the surface of SeNPs confer stability to the nanoparticles. SeNPs act as potent chemopreventive and chemotherapeutic agents. Conjugation with antibiotics enhances their anticancer efficacy. These also have applications in nanobiosensors and environmental remediation.

Phase-Engineered Type-II Multimetal-Selenide Heterostructures toward Low-Power Consumption, Flexible, Transparent, and Wide-Spectrum Photoresponse Photodetectors.

PubMed

Chen, Yu-Ze; Wang, Sheng-Wen; Su, Teng-Yu; Lee, Shao-Hsin; Chen, Chia-Wei; Yang, Chen-Hua; Wang, Kuangye; Kuo, Hao-Chung; Chueh, Yu-Lun

2018-05-01

Phase-engineered type-II metal-selenide heterostructures are demonstrated by directly selenizing indium-tin oxide to form multimetal selenides in a single step. The utilization of a plasma system to assist the selenization facilitates a low-temperature process, which results in large-area films with high uniformity. Compared to single-metal-selenide-based photodetectors, the multimetal-selenide photodetectors exhibit obviously improved performance, which can be attributed to the Schottky contact at the interface for tuning the carrier transport, as well as the type-II heterostructure that is beneficial for the separation of the electron-hole pairs. The multimetal-selenide photodetectors exhibit a response to light over a broad spectrum from UV to visible light with a high responsivity of 0.8 A W -1 and an on/off current ratio of up to 10 2 . Interestingly, all-transparent photodetectors are successfully produced in this work. Moreover, the possibility of fabricating devices on flexible substrates is also demonstrated with sustainable performance, high strain tolerance, and high durability during bending tests. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variation in the electrical properties of ion beam irradiated cadmium selenate nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauhan, R. P., E-mail: chauhanrpc@gmail.com; Narula, Chetna; Panchal, Suresh

The key feature of nanowires consists in the pronounced change in properties induced by the low dimensionality and high surface to volume ratio. The study of electrical transport properties of nanowires is important for electronic device applications. Energetic ions create changes, which may be structural or chemical, in a material along their track and these changes might alter the material’s properties. The demand of the modern technology is to understand the effect of radiation on the different properties of the material for its further applications. The present study is on the high-energy Nickel ion beam (160 MeV Ni{sup +12}) induced modificationsmore » in the electrical and structural properties of the cadmium selenate nanowires. An enhancement in the electrical conductivity of irradiated wires was observed as the ion fluence was increased especially in the forward I–V characteristics. The creation of defects by ion irradiation and the synergy of the ions during their passage in the sample with the intrinsic charge carriers may be responsible for the variation in the transport properties of the irradiated nanowires.« less

Toxicity and oxidative stress of different forms of organic selenium (Se) and dietary protein in mallard (Anas platyrhynchos) ducklings

USGS Publications Warehouse

Hoffman, D.; Heinz, G.; Eisemann, J.; Pendleton, G.

1994-01-01

High concentrations of Se have been found in aquatic food chains associated with irrigation drainwater and toxicity to fish and wildlife. Earlier studies have compared toxicities of Se as selenite and as seleno-DL-methionine (DL) in mallards. This study compares DL, seleno-L-methionine (L), selenized yeast (Y) and selenized wheat (W). Day-old mallard ducklings received an untreated diet (controls) containing 75% wheat (22% protein) or the same diet containing 15 or 30 ppm Se in the above forms. After 2 weeks blood and liver samples were collected for biochemical assays and Se analysis. All forms of selenium caused significant increases in plasma and hepatic glutathione peroxidase activities. Se as L was the most toxic, resulting in high mortality (64%) and impaired growth (>50%) and the greatest increase in ratio of oxidized to reduced glutathione with 30 ppm in the diet. Se as Y accumulated the least in liver. In a subsequent experiment with 30% dietary protein Se as L was less toxic.

Optimization of selenylation modification for garlic polysaccharide based on immune-enhancing activity.

PubMed

Gao, Zhenzhen; Chen, Jin; Qiu, Shulei; Li, Youying; Wang, Deyun; Liu, Cui; Li, Xiuping; Hou, Ranran; Yue, Chanjuan; Liu, Jie; Li, Hongquan; Hu, Yuanliang

2016-01-20

Garlic polysaccharide (GPS) was modified in selenylation respectively by nitric acid-sodium selenite (NA-SS), glacial acetic acid-selenous acid (GA-SA), glacial acetic acid-sodium selenite (GA-SS) and selenium oxychloride (SOC) methods each under nine modification conditions of L9(3(4)) orthogonal design and each to obtain nine selenizing GPSs (sGPSs). Their structures were identified, yields and selenium contents were determined, selenium yields were calculated, and the immune-enhancing activities of four sGPSs with higher selenium yields were compared taking unmodified GPS as control. The results showed that among four methods the selenylation efficiency of NA-SS method were the highest, the activity of sGPS5 was the strongest and significantly stronger than that of unmodified GPS. This indicates that selenylation modification can significantly enhance the immune-enhancing activity of GPS, NA-SS method is the best method and the optimal conditions are 0.8:1 weight ratio of sodium selenite to GPS, reaction temperature of 70 °C and reaction time of 10h. Copyright © 2015 Elsevier Ltd. All rights reserved.

Broadband and polarization reflectors in the lookdown, Selene vomer

PubMed Central

Zhao, Shulei; Brady, Parrish Clawson; Gao, Meng; Etheredge, Robert Ian; Kattawar, George W.; Cummings, Molly E.

2015-01-01

Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields. PMID:25673301

Monolayer PtSe 2 , a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt

DOE PAGES

Wang, Yeliang; Li, Linfei; Yao, Wei; ...

2015-05-21

For single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. We found that a combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrastmore » to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.« less

Barium selenate supplementation and its effect on intramammary infection in pasture-based dairy cows.

PubMed

Ceballos, A; Kruze, J; Barkema, H W; Dohoo, I R; Sanchez, J; Uribe, D; Wichtel, J J; Wittwer, F

2010-04-01

A significant proportion of cattle receive inadequate dietary Se because of its low content in soils and pastures of various regions of the world. Several economically important diseases in dairy cows, such as mastitis, have been associated with Se deficiency. The objective of this study was to evaluate the effect of a single injection of a long-acting form of Se at drying off on the risk and incidence rate of new intramammary infections and on milk somatic cell count in the subsequent lactation in pasture-based dairy cows. Forty-nine Chilean Holstein-Friesian cows were fed a diet containing <0.05 mg of Se/kg of ration dry matter. During the dry period, cows were allocated to 1 of 2 groups, a supplemented (n=24) group treated with a single subcutaneous injection of barium selenate 2 mo before calving and a control group (n=25) that remained unsupplemented. Duplicate foremilk samples were aseptically collected within 6 d after calving and every 2 wk until drying-off for bacteriological culture. Milk samples were also collected monthly for somatic cell count evaluation. Blood samples were collected before treatment and at 30, 90, 180, and 270 d after treatment for analysis of blood glutathione peroxidase (GPx) activity. The activity of glutathione peroxidase was higher in supplemented cows 30 d after the injection until the end of the study. The risk and incidence rate of new intramammary infections was not affected by supplementation. A progressive increase in somatic cell count was observed throughout lactation, but there was no effect of supplementation. In conclusion, a one-time injection of barium selenate 2 mo before calving in these pasture-based dairy cows did not affect udder health in the subsequent lactation, indicating that Se basal intake was adequate for preventing subclinical mastitis in pasture-based cows in southern Chile. Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Biological alkylation and colloid formation of selenium in methanogenic UASB reactors.

PubMed

Lenz, Markus; Smit, Martijn; Binder, Patrick; van Aelst, Adriaan C; Lens, Piet N L

2008-01-01

Bioalkylation and colloid formation of selenium during selenate removal in upflow anaerobic sludge bed (UASB) bioreactors was investigated. The mesophilic (30 degrees C) UASB reactor (pH = 7.0) was operated for 175 d with lactate as electron donor at an organic loading rate of 2 g COD L(-1) d(-1) and a selenium loading rate of 3.16 mg Se L(-1) d(-1). Combining sequential filtration with ion chromatographic analysis for selenium oxyanions and solid phase micro extraction gas chromatography mass spectrometry (SPME-GC-MS) for alkylated selenium compounds allowed to entirely close the selenium mass balance in the liquid phase for most of the UASB operational runtime. Although selenate was removed to more than 98.6% from the liquid phase, a less efficient removal of dissolved selenium was observed due to the presence of dissolved alkylated selenium species (dimethylselenide and dimethyldiselenide) and colloidal selenium particles in the effluent. The alkylated and the colloidal fractions contributed up to 15 and 31%, respectively, to the dissolved selenium concentration. The size fractions of the colloidal dispersion were: 4 to 0.45 mum: up to 21%, 0.45 to 0.2 mum: up to 11%, and particles smaller than 0.2 mum: up to 8%. Particles of 4 to 0.45 mum were formed in the external settler, but did not settle. SEM-EDX analysis showed that microorganisms form these selenium containing colloidal particles extracellularly on their surface. Lowering the temperature by 10 degrees C for 6 h resulted in drastically reduced selenate removal efficiencies (after a delay of 1.5 d), accompanied by the temporary formation of an unknown, soluble, organic selenium species. This study shows that a careful process control is a prerequisite for selenium treatment in UASB bioreactors, as disturbances in the operational conditions induce elevated selenium effluent concentrations by alkylation and colloid formation.

Molybdenum accumulation, tolerance and molybdenum-selenium-sulfur interactions in Astragalus selenium hyperaccumulator and nonaccumulator species.

PubMed

DeTar, Rachael Ann; Alford, Élan R; Pilon-Smits, Elizabeth A H

2015-07-01

Some species hyperaccumulate selenium (Se) upwards of 0.1% of dry weight. This study addressed whether Se hyperaccumulators also accumulate and tolerate more molybdenum (Mo). A field survey revealed on average 2-fold higher Mo levels in three hyperaccumulator Astragali compared to three nonaccumulator Astragali, which were not significantly different. Next, a controlled study was performed where hyperaccumulators Astragalus racemosus and Astragalus bisulcatus were compared with nonaccumulators Astragalus drummondii and Astragalus convallarius for Mo accumulation and tolerance, alone or in the presence of Se. When grown on agar media with 0, 12, 24 or 48 mg L(-1) molybdate and/or 0, 1.6 or 3.2 mg L(-1) selenate, all species decreased in biomass with increasing Mo supply. Selenium did not impact biomass at the supplied levels. All Astragali accumulated Mo upwards of 0.1% of dry weight. Selenium levels were up to 0.08% in Astragalus racemosus and 0.04% Se in the other species. Overall, there was no correlation between Se hyperaccumulation and Mo accumulation capacity. However, the hyperaccumulators and nonaccumulators differed in some respects. While none of the species had a higher tissue Mo to sulfur (S) ratio than the growth medium, nonaccumulators had a higher Mo/S ratio than hyperaccumulators. Also, while molybdate and selenate reduced S accumulation in nonaccumulators, it did not in hyperaccumulators. Furthermore, A. racemosus had a higher Se/S ratio than its medium, while the other species did not. Additionally, Mo and Se treatment affected S levels in nonaccumulators, but not in hyperaccumulators. In conclusion, there is no evidence of a link between Se and Mo accumulation and tolerance in Astragalus. Sulfate transporters in hyperaccumulating Astragali appear to have higher sulfate specificity over other oxyanions, compared to nonaccumulators, and A. racemosus may have a transporter with enhanced selenate specificity relative to sulfate or molybdate. Copyright © 2015 Elsevier GmbH. All rights reserved.

Transparency of Water: A Workshop on Math, Water, and Justice

ERIC Educational Resources Information Center

Gonzalez-Carillo, Selene; Merson, Martha

2013-01-01

If a teacher is an environmental organizer, like Selene Gonzales-Carillo, the classroom is a conference room, the community garden, or a church parking lot. Students are everyone--from toddlers to the elderly; they come with a variety of levels of formal education. The goal is to increase environmental justice, community well-being, and…

Nutritional and supranutritional levels of selenate differentially suppress prostate tumor growth in adult but not young nude mice

USDA-ARS?s Scientific Manuscript database

Selenium (Se) is known to regulate carcinogenesis and immunity at nutritional and 26 supranutritional levels. Because the immune system provides critical defenses against 27 cancer and the athymic, immune-deficient NU/J nude mice are known to gradually develop 28 CD8+ and CD4+ T cells extrathymicall...

Biological changes of green pea (Pisum sativum L.) by selenium enrichment.

PubMed

Garousi, Farzaneh; Kovács, Béla; Domokos-Szabolcsy, Éva; Veres, Szilvia

2017-03-01

Supplement of common fertilizers with selenium (Se) for crop production will be an effective way to produce selenium-rich food and feed. The value of green pea seeds and forages as alternative protein source can be improved by using agronomic biofortification. Therefore, biological changes of green pea (Pisum sativum L.) and influences of inorganic forms of Se (sodium selenite and sodium selenate) at different concentrations on the accumulation of magnesium (Mg) and phosphorus (P) were investigated in greenhouse experiment. 3 mg kg -1 of selenite had positive effects to enhance photosynthetic attributes and decrease lipid peroxidation significantly. At the same time, Se accumulation increased in all parts of plant by increasing Se supply. Moreover, Mg and P accumulations were significantly increased at 3 mg kg -1 selenite and 1 mg kg -1 selenate treatments, respectively. By contrast higher selenite concentrations (≥30 mg kg -1 ) exerted toxic effects on plants. Relative chlorophyll content, actual photochemical efficiency of PSII (Ф PSII ) and Mg accumulation showed significant decrease while membrane lipid peroxidation increased. Thus, the present findings prove Se biofortification has positive effects on biological traits of green pea to provide it as a proper functional product.

Aqueous Solution-Phase Selenized CuIn(S,Se)2 Thin Film Solar Cells Annealed under Inert Atmosphere.

PubMed

Oh, Yunjung; Yang, Wooseok; Kim, Jimin; Woo, Kyoohee; Moon, Jooho

2015-10-14

A nonvacuum solution-based approach can potentially be used to realize low cost, roll-to-roll fabrication of chalcopyrite CuIn(S,Se)2 (CISSe) thin film solar cells. However, most solution-based fabrication methods involve highly toxic solvents and inevitably require sulfurization and/or postselenization with hazardous H2S/H2Se gases. Herein, we introduce novel aqueous-based Cu-In-S and Se inks that contain an amine additive for producing a high-quality absorber layer. CISSe films were fabricated by simple deposition of Cu-In-S ink and Se ink followed by annealing under an inert atmosphere. Compositional and phase analyses confirmed that our simple aqueous ink-based method facilitated in-site selenization of the CIS layer. In addition, we investigated the molecular structures of our aqueous inks to determine how crystalline chalcopyrite absorber layers developed without sulfurization and/or postselenization. CISSe thin film solar cells annealed at 550 °C exhibited an efficiency of 4.55% under AM 1.5 illumination. The low-cost, nonvacuum method to deposit chalcopyrite absorber layers described here allows for safe and simple processing of thin film solar cells.

Lander and rover exploration on the lunar surface: A study for SELENE-B mission

NASA Astrophysics Data System (ADS)

Selene-B Rover Science Group; Sasaki, S.; Sugihara, T.; Saiki, K.; Akiyama, H.; Ohtake, M.; Takeda, H.; Hasebe, N.; Kobayashi, M.; Haruyama, J.; Shirai, K.; Kato, M.; Kubota, T.; Kunii, Y.; Kuroda, Y.

The SELENE-B, a lunar landing mission, has been studied in Japan, where a scientific investigation plan is proposed using a robotic rover and a static lander. The main theme to be investigated is to clarify the lunar origin and evolution, especially for early crustal formation process probably from the ancient magma ocean. The highest priority is placed on a direct in situ geology at a crater central peak, “a window to the interior”, where subcrustal materials are exposed and directly accessed without drilling. As a preliminary study was introduced by Sasaki et al. [Sasaki, S., Kubota, T., Okada, T. et al. Scientific exploration of lunar surface using a rover in Japanse future lunar mission. Adv. Space Res. 30, 1921 1926, 2002.], the rover and lander are jointly used, where detailed analyses of the samples collected by the rover are conducted at the lander. Primary scientific instruments are a multi-band stereo imager, a gamma-ray spectrometer, and a sampling tool on the rover, and a multi-spectral telescopic imager, a sampling system, and a sample analysis package with an X-ray spectrometer/diffractometer, a multi-band microscope as well as a sample cleaning and grinding device on the lander.

Use of olive leaves (whether or not fortified with sodium selenate) in rabbit feeding: Effect on performance, carcass and meat characteristics, and estimated indexes of fatty acid metabolism.

PubMed

Mattioli, Simona; Machado Duarte, Joana Margarida; Castellini, Cesare; D'Amato, Roberto; Regni, Luca; Proietti, Primo; Businelli, Daniela; Cotozzolo, Elisa; Rodrigues, Miguel; Dal Bosco, Alessandro

2018-09-01

Sixty New Zealand White weaned rabbits were divided into three groups and subjected to different dietary treatments: a standard diet for the control (C), a standard feed supplemented with 10% of plain olive leaves (OL) and a standard feed supplemented with 10% of selenium-fortified olive leaves (100 mg/L of foliar spray sodium selenate solution; SeOL). The productive performance was recorded at the time of slaughter (after 35 days); the carcass and meat traits were determined and estimated indexes of fatty acid metabolism were calculated. No significant differences were found on the rabbit productive performance and the physical-chemical characteristics of the meat. Both group of rabbits on the enriched diet showed leaner and thinner carcasses and a higher meat concentration of oleic acid. The estimated index of Δ5 + Δ6-desaturase, starting from n-6 fatty acids, was lower in both groups supplemented with leaves. The use of selenium-fortified olive leaves, positively affected the lipid oxidative stability of rabbit meat. Copyright © 2018 Elsevier Ltd. All rights reserved.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2007 and January 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2008-01-01

This report presents the results for two sampling periods (October 2007 and January 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (selenite, selenate, organoselenium), and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species?western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 0.97 to 64.5 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.95 to 5.99; plankton, 0.15 to 19.3; midges, 1.39 to 15.4; fish, 3.71 to 25.1; detritus, 0.85 to 21.7; sediment, 0.32 to 7.28.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (April 2008 and July 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples and total selenium was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species - western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.93 to 44.2 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.75 to 3.39; plankton, 0.88 to 4.03; midges, 2.52 to 44.3; fish, 3.37 to 18.9; detritus, 1.11 to 13.6; sediment, 0.11 to 8.93.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2008 and January 2009

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (October 2008 and January 2009) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples. Total selenium also was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species (western mosquitofish, Gambusia affinis, and sailfin molly, Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.00 to 33.6 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 1.52 to 8.26; plankton, 0.79 to 3.66; midges, 2.68 to 50.6; fish, 3.09 to 30.4; detritus, 1.78 to 58.0; and sediment, 0.42 to 10.0.

The antioxidative and hepatoprotective effects comparison of Chinese angelica polysaccharide(CAP)and selenizing CAP (sCAP) in CCl4 induced hepatic injury mice.

PubMed

Gao, Zhenzhen; Zhang, Chao; Tian, Weijun; Liu, Kuanhui; Hou, Ranran; Yue, Chanjuan; Wu, Yi; Wang, Deyun; Liu, Jiaguo; Hu, Yuanliang; Yang, Ying

2017-04-01

Chinese angelica polysaccharides (CAP) and selenizing CAP (sCAP) were prepared and identified through FTIR and SEM observation. Their antioxidant activities in vitro and hepatoprotective effects in vivo were compared by free radical-scavenging tests or with CCl 4 -induced hepatic injury model mice. The results showed that for DPPH radical, superoxide anion and hydroxyl radical, the scavenging capabilities of sCAP were significantly stronger than those of CAP . In hepatic injury model mice, sCAP could significantly reduce ALT, AST and ALP contents and raised TP content in serum, significantly reduce MDA and ROS contents and raised SOD and T-AOC activities in liver homogenate in comparison with CAP; obviously relieve the pathological changes of liver and significantly inhibit the expressions of p-ERK, p-JNK and p-p38 protein as compared with those in model control group. These results indicate that selenylation modification can enhance the antioxidant and hepatoprotective actions of Chinese angelica polysaccharide. A action mechanism of sCAP is suppressing the protein expression of MAPK signaling pathway. Copyright © 2017 Elsevier B.V. All rights reserved.

On-line pre-reduction of Se(VI) by thiourea for selenium speciation by hydride generation

NASA Astrophysics Data System (ADS)

Qiu, Jianhua; Wang, Qiuquan; Ma, Yuning; Yang, Limin; Huang, Benli

2006-07-01

In this study, thiourea (TU) was novelly developed as a reduction reagent for on-line pre-reduction of selenium(VI) before conventional hydride generation (HG) by KBH 4/NaOH-HCl. After TU on-line pre-reduction, the HG efficiency of Se(VI) has been greatly improved and because even higher than that of the same amount of Se(IV) obtained in the conventional HG system. The possible pre-reduction mechanism is discussed. The detection limit (DL) of selenate reaches 10 pg mL - 1 when using on-line TU pre-reduction followed by HG atomic fluorescence detection. When TU pre-reduction followed by HG is used as an interface between ion-pair high performance liquid chromatography and atomic fluorescence spectrometry, selenocystine, selenomethionine, selenite and selenate can be measured simultaneously and quantitatively. The DLs of these are 0.06, 0.08, 0.05 and 0.04 ng mL - 1 , respectively, and the relative standard deviations of 9 duplicate runs for all the 4 species are less than 5%. Furthermore, it was successfully applied to Se speciation analysis of cultured garlic samples, and validated by determination of total selenium and selenium species in certified reference material NIST 1946.

Sensory quality and chemical composition of meat from lambs fed diets enriched with fish and rapeseed oils, carnosic acid and seleno-compounds.

PubMed

Jaworska, Danuta; Czauderna, Marian; Przybylski, Wiesław; Rozbicka-Wieczorek, Agnieszka J

2016-09-01

The aim of the study was to evaluate longissimus muscle quality in lambs fed diets including fish oil (FO), rapeseed oil (RO), carnosic acid (CA) and seleno-compounds. Lambs were fed one of diets: Group I - the basal diet (BD) with 3% RO; Group II - BD with 2% RO and 1% FO; Group III - BD with 2% RO, 1% FO and 0.1% CA; Group IV - BD with 2% RO, 1% FO, 0.1% CA and 0.35ppm Se as selenized-yeast; Group V - BD with 2% RO, 1% FO, 0.1% CA and 0.35ppm Se as selenate. The addition of FO and FO, CA and selenium in the inorganic form was characterized by lowest tenderness and juiciness (P<0.05). The lowest concentration of fatty acids (ΣFAs), atherogenic-FAs (A(SFA)) and thrombogenic-FAs (T(SFA)) in the muscle was found for Group V (P<0.05). Experimental diets decreased indexes of A(SFA) and T(SFA) in muscle. The lowest ratio (P<0.05) of n-6polyunsaturated-FAs to n-3polyunsaturated-FAs was obtained for Group III. Copyright © 2016 Elsevier Ltd. All rights reserved.

Local Lunar Gravity Field Analysis over the South Pole-aitken Basin from SELENE Farside Tracking Data

NASA Technical Reports Server (NTRS)

Goossens, Sander Johannes; Ishihara, Yoshiaki; Matsumoto, Koji; Sasaki, Sho

2012-01-01

We present a method with which we determined the local lunar gravity field model over the South Pole-Aitken (SPA) basin on the farside of the Moon by estimating adjustments to a global lunar gravity field model using SELENE tracking data. Our adjustments are expressed in localized functions concentrated over the SPA region in a spherical cap with a radius of 45deg centered at (191.1 deg E, 53.2 deg S), and the resolution is equivalent to a 150th degree and order spherical harmonics expansion. The new solution over SPA was used in several applications of geophysical analysis. It shows an increased correlation with high-resolution lunar topography in the frequency band l = 40-70, and admittance values are slightly different and more leveled when compared to other, global gravity field models using the same data. The adjustments expressed in free-air anomalies and differences in Bouguer anomalies between the local solution and the a priori global solution correlate with topographic surface features. The Moho structure beneath the SPA basin is slightly modified in our solution, most notably at the southern rim of the Apollo basin and around the Zeeman crater

Broadband and polarization reflectors in the lookdown, Selene vomer.

PubMed

Zhao, Shulei; Brady, Parrish Clawson; Gao, Meng; Etheredge, Robert Ian; Kattawar, George W; Cummings, Molly E

2015-03-06

Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

SPECIATION OF SELENIUM AND ARSENIC COMPOUNDS BY CAPILLARY ELECTROPHORESIS WITH HYDRODYNAMICALLY MODIFIED ELECTROOSMOTIC FLOW AND ON-LINE REDUCTION OF SELENIUM(VI) TO SELENIUM(IV) WITH HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

EPA Science Inventory

Capillary electrophoresis (CE) with hydride generation inductively coupled plasma mass spectrometry was used to determine four arsenicals and two selenium species. Selenate (SeVI) was reduced on-line to selenite (SeIV') by mixing the CE effluent with concentrated HCl. A microporo...

Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi.

PubMed

Tran, Thi Anh Thu; Dinh, Quang Toan; Cui, Zeiwei; Huang, Jie; Wang, Dan; Wei, Tianjiao; Liang, Dongli; Sun, Xin; Ning, Ping

2018-01-01

Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se 4+ and Se 6+ ) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl 2 ) and selenite (Na 2 SeO 3 ) or selenate (Na 2 SeO 4 ) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg I R values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), I R values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the I R indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se 4+ or Se 6+ ). Copyright © 2017 Elsevier Inc. All rights reserved.

Thermal control unit for long-time survival of scientific instruments on lunar surface

NASA Astrophysics Data System (ADS)

Ogawa, Kazunori; Iijima, Yuichi; Tanaka, Satoshi

A thermal control unit (lunar survival module) is being developed for scientific instruments placed on the lunar surface. This unit is designed to be used on the future Japanese lunar landing mission SELENE-2. The lunar surface is a severe environment for scientific instruments. The absence of convective cooling by an atmosphere makes the ground surface temperature variable in the wide range of -200 to 100 degC, an environment in which space electronics can hardly survive. The surface elements must have a thermal control structure to maintain the inner temperature within the operable ranges of the instruments for long-time measurements, such as 1 month or longer beyond the lunar nights. The objectives of this study are to develop a thermal control unit for the SELENE-2 mission. So far, we conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. The basic structure of the thermal module is rather simple in that a heat insulating shell covers the scientific instruments. The concept is that the conical insulator retains heat in the regolith soil in the daylight, and it can keep the device warm in the night. Results of the model calculations indicated the high potential of long-time survival. A bread board model (BBM) was manufactured, and its thermal-vacuum tests were conducted in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The thermal condition of the lunar surface was simulated by glass beads paved in a vacuum chamber, and a temperature-controlled container. Temperature variations of the BBM in thermal cycling tests were compared to a thermal mathematical model, and the thermal parameters were finally assessed. Feeding the test results back into the thermal model for the lunar surface, some thermal parameters were updated but there was no critical effect on the survivability. The experimental results indicated a sufficient survivability potential of the concept of our thermal control system.

Biokinetic food chain modeling of waterborne selenium pulses into aquatic food chains: Implications for water quality criteria.

PubMed

DeForest, David K; Pargee, Suzanne; Claytor, Carrie; Canton, Steven P; Brix, Kevin V

2016-04-01

We evaluated the use of biokinetic models to predict selenium (Se) bioaccumulation into model food chains after short-term pulses of selenate or selenite into water. Both periphyton- and phytoplankton-based food chains were modeled, with Se trophically transferred to invertebrates and then to fish. Whole-body fish Se concentrations were predicted based on 1) the background waterborne Se concentration, 2) the magnitude of the Se pulse, and 3) the duration of the Se pulse. The models were used to evaluate whether the US Environmental Protection Agency's (USEPA's) existing acute Se criteria and their recently proposed intermittent Se criteria would be protective of a whole-body fish Se tissue-based criterion of 8.1 μg g(-1) dry wt. Based on a background waterborne Se concentration of 1 μg L(-1) and pulse durations of 1 d and 4 d, the Se pulse concentrations predicted to result in a whole-body fish Se concentration of 8.1 μg g(-1) dry wt in the most conservative model food chains were 144 and 35 μg L(-1), respectively, for selenate and 57 and 16 μg L(-1), respectively, for selenite. These concentrations fall within the range of various acute Se criteria recommended by the USEPA based on direct waterborne toxicity, suggesting that these criteria may not always be protective against bioaccumulation-based toxicity that could occur after short-term pulses. Regarding the USEPA's draft intermittent Se criteria, the biokinetic modeling indicates that they may be overly protective for selenate pulses but potentially underprotective for selenite pulses. Predictions of whole-body fish Se concentrations were highly dependent on whether the food chain was periphyton- or phytoplankton-based, because the latter had much greater Se uptake rate constants. Overall, biokinetic modeling provides an approach for developing acute Se criteria that are protective against bioaccumulation-based toxicity after trophic transfer, and it is also a useful tool for evaluating averaging periods for chronic Se criteria. © 2015 SETAC.

Methods of forming CIGS films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansfield, Lorelle; Ramanathan, Kannan

2017-09-19

Methods for forming CIGS films are provided. According to an aspect of the invention, a method of forming a CIGS film includes a precursor step, which includes simultaneously evaporating Cu, In, Ga, Se, and Sb onto a substrate. The Se is incident on the substrate at a rate of at least 20 .ANG./s. The method also includes a selenization step, which includes evaporating Se over the substrate after the precursor step.

In Situ Bioremediation of Perchlorate in Vadose Zone Soil Using Gaseous Electron Donors

DTIC Science & Technology

2009-11-01

National Aeronautics and Space Administration ND Non-detect NDMA N-Nitrosodimethylamine No. Number NO3- Nitrate OD Outside diameter O&M...Nitrite xv • Selenate • Arsenate • Chromate and dichromate (i.e., hexavalent chromium) • Uranylate • Pertechnetate • N-Nitrosodimethylamine ( NDMA ...Arsenate • Chromate and dichromate (i.e., hexavalent chromium) • Uranylate • Pertechnetate • N-Nitrosodimethylamine ( NDMA ) • Trichloroethene (TCE

A New Lunar Digital Elevation Model from the Lunar Orbiter Laser Altimeter and SELENE Terrain Camera

NASA Technical Reports Server (NTRS)

Barker, M. K.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Haruyama, J.; Smith, D. E.

2015-01-01

We present an improved lunar digital elevation model (DEM) covering latitudes within +/-60 deg, at a horizontal resolution of 512 pixels per degree ( approx.60 m at the equator) and a typical vertical accuracy approx.3 to 4 m. This DEM is constructed from approx.4.5 ×10(exp 9) geodetically-accurate topographic heights from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter, to which we co-registered 43,200 stereo-derived DEMs (each 1 deg×1 deg) from the SELENE Terrain Camera (TC) ( approx.10(exp 10) pixels total). After co-registration, approximately 90% of the TC DEMs show root-mean-square vertical residuals with the LOLA data of < 5 m compared to approx.50% prior to co-registration. We use the co-registered TC data to estimate and correct orbital and pointing geolocation errors from the LOLA altimetric profiles (typically amounting to < 10 m horizontally and < 1 m vertically). By combining both co-registered datasets, we obtain a near-global DEM with high geodetic accuracy, and without the need for surface interpolation. We evaluate the resulting LOLA + TC merged DEM (designated as "SLDEM2015") with particular attention to quantifying seams and crossover errors.

Pilot-Scale Selenium Bioremediation of San Joaquin Drainage Water with Thauera selenatis

PubMed Central

Cantafio, A. W.; Hagen, K. D.; Lewis, G. E.; Bledsoe, T. L.; Nunan, K. M.; Macy, J. M.

1996-01-01

This report describes a simple method for the bioremediation of selenium from agricultural drainage water. A medium-packed pilot-scale biological reactor system, inoculated with the selenate-respiring bacterium Thauera selenatis, was constructed at the Panoche Water District, San Joaquin Valley, Calif. The reactor was used to treat drainage water (7.6 liters/min) containing both selenium and nitrate. Acetate (5 mM) was the carbon source-electron donor reactor feed. Selenium oxyanion concentrations (selenate plus selenite) in the drainage water were reduced by 98%, to an average of 12 (plusmn) 9 (mu)g/liter. Frequently (47% of the sampling days), reactor effluent concentrations of less than 5 (mu)g/liter were achieved. Denitrification was also observed in this system; nitrate and nitrite concentrations in the drainage water were reduced to 0.1 and 0.01 mM, respectively (98% reduction). Analysis of the reactor effluent showed that 91 to 96% of the total selenium recovered was elemental selenium; 97.9% of this elemental selenium could be removed with Nalmet 8072, a new, commercially available precipitant-coagulant. Widespread use of this system (in the Grasslands Water District) could reduce the amount of selenium deposited in the San Joaquin River from 7,000 to 140 lb (ca. 3,000 to 60 kg)/year. PMID:16535401

Selenium speciation in malt, wort, and beer made from selenium-biofortified two-rowed barley grain.

PubMed

Rodrigo, Sara; Santamaria, Oscar; Chen, Yi; McGrath, Steve P; Poblaciones, Maria J

2014-06-25

Selenium (Se) biofortification of barley is a suitable strategy to increase the Se concentration in grain. In the present paper, the suitability of this Se-biofortified grain for making Se-enriched beer is analyzed. The aim of the present study was to evaluate the effect of different Se fertilizer doses (0, 10, and 20 g of Se ha(-1)) and forms (sodium selenate or sodium selenite) on the Se loss during the malting and brewing processes and Se speciation in grain, malt, wort, and beer. Samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS for total Se and speciation. Mashing-lautering was the process with the greatest Se loss (83.8%). After malting and brewing, only 7.3% of the initial Se was retained in beer, mainly in selenite form. Even so, the fertilizer application of sodium selenate at 20 g ha(-1) increased the total Se concentration almost 6-fold in the final beer in comparison to the use of grain derived from unfertilized barley. The present paper provides evidence that the use of Se-biofortified barley grain as a raw material to produce Se-enriched beer is possible, and the results are comparable to other methods in terms of efficiency.

A thermal control system for long-term survival of scientific instruments on lunar surface.

PubMed

Ogawa, K; Iijima, Y; Sakatani, N; Otake, H; Tanaka, S

2014-03-01

A thermal control system is being developed for scientific instruments placed on the lunar surface. This thermal control system, Lunar Mission Survival Module (MSM), was designed for scientific instruments that are planned to be operated for over a year in the future Japanese lunar landing mission SELENE-2. For the long-term operations, the lunar surface is a severe environment because the soil (regolith) temperature varies widely from nighttime -200 degC to daytime 100 degC approximately in which space electronics can hardly survive. The MSM has a tent of multi-layered insulators and performs a "regolith mound". Temperature of internal devices is less variable just like in the lunar underground layers. The insulators retain heat in the regolith soil in the daylight, and it can keep the device warm in the night. We conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. Thermal vacuum tests were also conducted by using a thermal evaluation model in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The numerical and experimental results indicated a sufficient survivability potential of the concept of our thermal control system.

Production and Release of Selenomethionine and Related Organic Selenium Species by Microorganisms in Natural and Industrial Waters.

PubMed

LeBlanc, Kelly L; Wallschläger, Dirk

2016-06-21

Laboratory algal cultures exposed to selenate were shown to produce and release selenomethionine, selenomethionine oxide, and several other organic selenium metabolites. Released discrete organic selenium species accounted for 1.6-13.1% of the selenium remaining in the media after culture death, with 1.3-6.1% of the added selenate recovered as organic metabolites. Analysis of water from an industrially impacted river collected immediately after the death of massive annual algal blooms showed that no selenomethionine or selenomethionine oxide was present. However, other discrete organic selenium species, including a cyclic oxidation product of selenomethionine, were observed, indicating the previous presence of selenomethionine. Industrial biological treatment systems designed for remediation of selenium-contaminated waters were shown to increase both the concentration of organic selenium species in the effluent, relative to influent water, and the fraction of organic selenium to up to 8.7% of the total selenium in the effluent, from less than 1.1% in the influent. Production and emission of selenomethionine, selenomethionine oxide, and other discrete organic selenium species were observed. These findings are discussed in the context of potentially increased selenium bioavailability caused by microbial activity in aquatic environments and biological treatment systems, despite overall reductions in total selenium concentration.

Selenium modification of β-lactoglobulin (β-Lg) and its biological activity.

PubMed

Zheng, GuoQiang; Liu, HaoYu; Zhu, ZhenYuan; Zheng, Jie; Liu, AnJun

2016-08-01

β-Lg is a major whey protein in cow's milk. This study was aimed to find a new kind of organic selenium compound synthesized with β-Lg and selenium dioxide as raw materials under the conditions of vacuum and low temperature. Fourier transformed infrared spectroscopy revealed that seleno-β-lactoglobulin (Se-β-Lg) displayed a strong band at 878cm(-1), belonging to SeO. Circular dichroism spectra results indicated that the conformation of Se-β-Lg was transformed and α-helical, and unordered structures were increased by 9% and 11.2%, respectively, while β-sheet and β-turn were reduced by 14.2% and 6%, respectively. Electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry results showed that there were two protein bands (1-Seβ-Lg and 2-Seβ-Lg) in Se-β-Lg, only one β-Lg connected with selenate in 1-Seβ-Lg, but two β-Lgs, connected to each other, and with selenate, in 2-Seβ-Lg. Morphological observation and hematoxylin and eosin staining indicated that Se-β-lg could induce K562 cell apoptosis. These results indicated that Se-β-Lg could be synthesized by selenium conjugating β-Lg and it had antitumor activity. Copyright © 2016. Published by Elsevier Ltd.

Simultaneous quantitation and identification of organic and inorganic selenium in diet supplements by liquid chromatography with tandem mass spectrometry.

PubMed

Zembrzuska, Joanna; Matusiewicz, Henryk; Polkowska-Motrenko, Halina; Chajduk, Ewelina

2014-01-01

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for selenium speciation in dietary supplements. Chromatographic separation was performed on a TSK-Gel ODS-100V column using a mixture of 5mM ammonium acetate water solution and methanol as a mobile phase. Conditions chosen for this process allowed to separate all investigated chemical compounds of selenium: seleno-l-methionine, methyl-seleno-l-cysteine, l-selenocystine, methaneseleninic acid, selenite and selenate. A tandem mass spectrometer with an ion trap operating in negative or positive ion mode according to the selenium form being determined was used as a detector. Three extraction procedures: water extraction, enzymatic hydrolysis and sequential extraction were used for preparation of samples for the determination of the actual forms of selenium in diet supplements. The developed method was used for analysis of six dietary supplements containing selenium bought in a pharmacy and supermarket. Apart from speciation analysis of selenium content in supplements total selenium content was determined using instrumental neutron activation analysis (INAA). All expected forms of selenium except for selenite were determined using LC-MS/MS technique. It should be stressed that amounts of selenate were smaller than expected. Copyright © 2013 Elsevier Ltd. All rights reserved.

Escherichia coli tRNA 2-selenouridine synthase (SelU) converts S2U-RNA to Se2U-RNA via S-geranylated-intermediate.

PubMed

Sierant, Malgorzata; Leszczynska, Grazyna; Sadowska, Klaudia; Komar, Patrycja; Radzikowska-Cieciura, Ewa; Sochacka, Elzbieta; Nawrot, Barbara

2018-06-04

To date the only tRNAs containing nucleosides modified with a selenium (5-carboxymethylaminomethyl-2-selenouridine and 5-methylaminomethyl-2-selenouridine) have been found in bacteria. By using tRNA anticodon-stem-loop fragments containing S2U, Se2U, or geS2U, we found that in vitro tRNA 2-selenouridine synthase (SelU) converts S2U-RNA to Se2U-RNA in a two-step process involving S2U-RNA geranylation (with ppGe) and subsequent selenation of the resulting geS2U-RNA (with SePO 3 3- ). No 'direct' S2U-RNA→Se2U-RNA replacement is observed in the presence of SelU/SePO 3 3- only (without ppGe). These results suggest that the in vivo S2U→Se2U and S2U→geS2U transformations in tRNA, so far claimed to be the elementary reactions occurring independently in the same domain of the SelU enzyme, should be considered a combination of two consecutive events - geranylation (S2U→geS2U) and selenation (geS2U→Se2U). © 2018 Federation of European Biochemical Societies.

Selenium supplementation in pediatric patients using parenteral nutrition: Is it time to do something?

PubMed

Freitas, Renata Germano Borges de Oliveira Nascimento; Nogueira, Roberto José Negrão; Hessel, Gabriel

2018-03-01

To analyze the nutritional status of selenium and verify the effect of its supplementation in pediatric patients during 14 days of parenteral nutrition (PN). This is a series of cases with patients followed for two weeks while using PN. Data collection was performed at the beginning (T0), in the 7th (T1) and 14th days of PN (T2). The supplemented group received 2 µg/kg/day of selenous acid. Weight and height were measured for nutritional status assessment. Tests requested: plasma selenium, albumin, pre-albumin, C-reactive protein (CRP), total cholesterol and HDL-cholesterol. Fourteen (14) patients with inflammatory process and with low or very low weight for their ages were evaluated. In both groups (with and without supplementation), all patients had low selenium levels. Median plasma selenium concentrations were 17.4 µg/L (T0), 23.0 µg/L (T1) and 20.7 µg/L (T2). Increase and reduction of selenium occurred both in patients with high CRP and in those presenting normalization of this parameter. Lower plasma selenium levels have been detected since the start of the research and supplementation (2 µg/kg/day of selenous acid) was not to enough to approach the reference values.

Photochemistry of 1,4-dihydronaphtho(1,8-de)(1,2)diazepine. Preparation and electron spin resonance observation of the unsubstituted 1,8-naphthoquinodimethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagni, R.M.; Burnett, M.N.; Dodd, J.R.

1977-03-16

In an attempt to prepare selenated tRNA, transformation of 4-thiouridine to selenouridine in tRNA was attempted. Feasibility studies were performed by spectrophotometrically monitored conversion of 1 methyl-4- thiocyanatouracil to 1-methyl-4-selenouracil by NaHSe. E.coli mixed tRNA were exposed to the same sequence of reactions and the identity of the products was confirmed. (DDA)

SSTAC/ARTS review of the draft Integrated Technology Plan (ITP). Volume 3: Space power and thermal management

NASA Technical Reports Server (NTRS)

1991-01-01

Viewgraphs of briefings from the SSTAC/ARTS review of the draft integrated technology plan on thermal power and thermal management are presented. Topics covered include: space energy conversion research and technology; space photovoltaic energy conversion; chemical energy conversion and storage; thermal energy conversion; power management; thermal management; space nuclear power; high capacity power; surface power and thermal management; space platforms power and thermal management; and project SELENE.

SSTAC/ARTS review of the draft Integrated Technology Plan (ITP). Volume 3: Space power and thermal management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Viewgraphs of briefings from the SSTAC/ARTS review of the draft integrated technology plan on thermal power and thermal management are presented. Topics covered include: space energy conversion research and technology; space photovoltaic energy conversion; chemical energy conversion and storage; thermal energy conversion; power management; thermal management; space nuclear power; high capacity power; surface power and thermal management; space platforms power and thermal management; and project SELENE.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer

PubMed Central

Zhang, Zhaojing; Yao, Liyong; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming‐Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2017-01-01

Abstract Double layer distribution exists in Cu2SnZnSe4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double‐layer distribution of CZTSe film is eliminated entirely and the formation of MoSe2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSex mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu‐Sn‐Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu2Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm2 and a CZTSe solar cell with efficiency of 7.2% is fabricated. PMID:29610727

Involvement of Silicon Influx Transporter OsNIP2;1 in Selenite Uptake in Rice1[W][OA

PubMed Central

Zhao, Xue Qiang; Mitani, Namiki; Yamaji, Naoki; Shen, Ren Fang; Ma, Jian Feng

2010-01-01

Rice (Oryza sativa) as a staple food, provides a major source of dietary selenium (Se) for humans, which essentially requires Se, however, the molecular mechanism for Se uptake is still poorly understood. Herein, we show evidence that the uptake of selenite, a main bioavailable form of Se in paddy soils, is mediated by a silicon (Si) influx transporter Lsi1 (OsNIP2;1) in rice. Defect of OsNIP2;1 resulted in a significant decrease in the Se concentration of the shoots and xylem sap when selenite was given. However, there was no difference in the Se concentration between the wild-type rice and mutant of OsNIP2;1 when selenate was supplied. A short-term uptake experiment showed that selenite uptake greatly increased with decreasing pH in the external solution. Si as silicic acid did not inhibit the Se uptake from selenite in both rice and yeast (Saccharomyces cerevisiae) at low pHs. Expression of OsNIP2;1 in yeast enhanced the selenite uptake at pH 3.5 and 5.5 but not at pH 7.5. On the other hand, defect of Si efflux transporter Lsi2 did not affect the uptake of Se either from selenite or selenate. Taken together, our results indicate that Si influx transporter OsNIP2;1 is permeable to selenite. PMID:20498338

A thermal control system for long-term survival of scientific instruments on lunar surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, K., E-mail: ogawa@astrobio.k.u-tokyo.ac.jp; Iijima, Y.; Tanaka, S.

2014-03-15

A thermal control system is being developed for scientific instruments placed on the lunar surface. This thermal control system, Lunar Mission Survival Module (MSM), was designed for scientific instruments that are planned to be operated for over a year in the future Japanese lunar landing mission SELENE-2. For the long-term operations, the lunar surface is a severe environment because the soil (regolith) temperature varies widely from nighttime −200 degC to daytime 100 degC approximately in which space electronics can hardly survive. The MSM has a tent of multi-layered insulators and performs a “regolith mound”. Temperature of internal devices is lessmore » variable just like in the lunar underground layers. The insulators retain heat in the regolith soil in the daylight, and it can keep the device warm in the night. We conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. Thermal vacuum tests were also conducted by using a thermal evaluation model in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The numerical and experimental results indicated a sufficient survivability potential of the concept of our thermal control system.« less

Synthesis, characterization and thermal decomposition of tetramethylammonium rare earth double selenates

NASA Astrophysics Data System (ADS)

Divekar, Sandesh K.; Achary, S. Nagabhusan; Ajgaonkar, Vishnu R.

2018-06-01

A series of double selenates, as (CH3)4NLn(SeO4)2rad 4H2O (Ln = Rare earth ion like La, Pr, Nd, Sm, Gd, Tb, Dy) was crystallized from mixed solution and characterized in detail for their structure, vibrational and optical properties as well as thermal stabilities. The crystal structure of the praseodymium compound was obtained by single crystal X-ray diffraction (XRD) and revealed a monoclinic (C2/c) lattice with chains formed by PrO8 and SeO4 units. The chains with compositions [Pr(SeO4)4(H2O)4]- are stacked in three dimensions and the (CH3)4N+ ions located in between them provide charge neutrality to the structure. The characterization of other compounds were carried out from powder XRD data and revealed that they all are isostructural to Pr-compound. All the functional groups were identified by Raman and IR spectroscopic studies. Solid state 77Se NMR revealed noticeable changes in selenium environment in these compounds. The optical absorption studies on the compounds show strong band edge absorptions in UV region. Thermal stabilities of the compounds, as investigated by simultaneous TG-DTA techniques indicate their sequential decompositions due to loss of H2O, (CH3)4N+ group, SeO2 and finally leaving their corresponding rare earth oxides.

The possible effect of reaction wheel unloading on orbit determination for Chang'E-1 lunar mission

NASA Astrophysics Data System (ADS)

Jianguo, Yan; Jingsong, Ping; Fei, Li

During the flight of 3-axis stabilized lunar orbiter i e SELENE main orbiter Chang E-1 due to the overflow of the accumulated angular momentum the reaction-wheel will be unloaded during certain period so as to release the angular momentum for initialization Then the momentum wheel will be reloaded for satellite attitude measurement and control Above action will not only change the attitude but also change the orbit of the spacecraft Assuming the reaction-wheel unloading is carried out twice a day according to the current engineering designation and plan for SELENE main orbiter and Chang E-1 missions considering the algebra configuration of the tracking stations the Moon and the lunar orbiter the orbit determination is simulated for 14 days evolution of lunar orbiter In the simulation the satellite orbit is generated using GEODYNII code Based on the generated orbit the common view time period of the satellite by VLBI and USB network in every day is computed the orbit determination is processed for all the arcs of the orbit The orbit determination result of 28 orbits in 14 days is provided The orbits cover most of the possible geometrical configuration among orbiter the Moon and the tracking network The analysis here can benefit the tracking designation and plan for Chang E-1 mission

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

PubMed

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

Lunar and Planetary Science XXXVI, Part 15

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Impact Metamorphism of Subsurface Organic Matter on Mars: A Potential Source for Methane and Surface Alteration. Preliminary Study of Polygonal Impact Craters in Argyre Region, Mars. Geochemistry of the Dark Veinlets in the Granitoids from the Souderfjarden Impact Structure, Finland: Preliminary Results. An Experimental Method to Estimate the Chemical Reaction Rate in Vapor Clouds: An Application to the K/T Impact. Study of the Apollo 16 Landing Site: Re-Visit as a Standard Site for the SELENE Multiband Imager. First X-Ray Observation of Lunar Farside from Hayabusa X-Ray Spectrometer. Lunar X-Ray Fluorescence Spectrometry from SELENE Lunar Polar Orbiter. Origin and Thermal History of Lithic Materials in the Begaa LL3 Chondrite. Evidence of Normal Faulting and Dike Intrusion at Valles Marineris from Pit Crater Topography. Evidence of Tharsis-Radial Dike Intrusion in Southeast Alba Patera from MOLA-based Topography of Pit Crater Chains. Are They Really Intact? Evaluation of Captured Micrometeoroid Analogs by Aerogel at the Flyby Speed of Stardust. Numerical Simulations of Impactor Penetration into Ice-Over-Water Targets. A Probable Fluid Lava Flow in the Hebes Mensa (Mars) Studied by HRSC Images. New Drill-Core Data from the Lockne Crater, Sweden: The Marine Excavation and Ejection Processes, and Post-Impact Environment. Cross-Sectional Profile of Baltis Vallis Channel on Venus: Reconstruction from Magellan SAR Brightness Data.

Speciation of Se and DOC in soil solution and their relation to Se bioavailability.

PubMed

Weng, Liping; Vega, Flora Alonso; Supriatin, Supriatin; Bussink, Wim; Van Riemsdijk, Willem H

2011-01-01

A 0.01 M CaCl(2) extraction is often used to asses the bioavailability of plant nutrients in soils. However, almost no correlation was found between selenium (Se) in the soil extraction and Se content in grass. The recently developed anion Donnan membrane technique was used to analyze chemical speciation of Se in the 0.01 M CaCl(2) extractions of grassland soils and fractionation of DOC (dissolved organic carbon). The results show that most of Se (67-86%) in the extractions (15 samples) are colloidal-sized Se. Only 13-34% of extractable Se are selenate, selenite and small organic Se (<1 nm). Colloidal Se is, most likely, Se bound to or incorporated in colloidal-sized organic matter. The dominant form of small Se compounds (selenate, selenite/small organic compounds) depends on soil. A total of 47-85% of DOC is colloidal-sized and 15-53% are small organic molecules (<1 nm). In combination with soluble S (sulfur) and/or P (phosphor), concentration of small DOC can explain most of the variability of Se content in grass. The results indicate that mineralization of organic Se is the most important factor that controls Se availability in soils. Competition with sulfate and phosphate needs to be taken into account. Further research is needed to verify if concentration of small DOC is a good indicator of mineralization of soil organic matter.

Synthesis and crystal structure of Fe[(Te1.5Se0.5)O5]Cl, the first iron compound with selenate(IV) and tellurate(IV) groups

NASA Astrophysics Data System (ADS)

Akhrorov, Akhmad Yu; Kuznetsova, Elena S.; Aksenov, Sergey M.; Berdonosov, Peter S.; Kuznetsov, Alexey N.; Dolgikh, Valery A.

2017-12-01

During the search for selenium analogues of FeTe2O5Cl, the new iron (III) tellurate(IV) selenate(IV) chloride with the composition Fe[(Te1.5Se0.5)O5]Cl was synthesized by chemical vapor transport (CVT) reaction and characterized by TGA-, EDX-,SCXRD-analysis, as well as IR and Raman spectroscopy. It was found that Fe[(Te1.5Se0.5)O5]Cl crystallizes in the monoclinic space group P21/c with unitcell parameters a = 5.183(3) Å, b = 15.521(9) Å, c = 7.128(5) Å and β = 107.16(1)°. The crystal structure of Fe[(Te1.5Se0.5)O5]Cl represents a new structure type and contains electroneutral heteropolyhedral layers formed by dimers of the [FeO5Cl]8- octahedra, linked via common O-O edges, and mixed [Te3SeO10]4- tetramers. Adjacent layers are stacked along the b axis and linked by weak residual bonds. The new compound is stable up to 420 °C. DFT calculations predict Fe[(Te1.5Se0.5)O5]Cl to be a wide-gap semiconductor with the band gap of ca. 2.7 eV.

Fullerene-like MoSe2 nanoparticles-embedded CNT balls with excellent structural stability for highly reversible sodium-ion storage

NASA Astrophysics Data System (ADS)

Choi, Seung Ho; Kang, Yun Chan

2016-02-01

Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls.Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07733h

Method of removing arsenic and other anionic contaminants from contaminated water using enhanced coagulation

DOEpatents

Teter, David M.; Brady, Patrick V.; Krumhansl, James L.; Khandaker, Nadim R.

2006-11-21

An improved water decontamination process comprising contacting water containing anionic contaminants with an enhanced coagulant to form an enhanced floc, which more efficiently binds anionic species (e.g., arsenate, arsenite, chromate, fluoride, selenate, and borate, and combinations thereof) predominantly through the formation of surface complexes. The enhanced coagulant comprises a trivalent metal cation coagulant (e.g., ferric chloride or aluminum sulfate) mixed with a divalent metal cation modifier (e.g., copper sulfate or zinc sulfate).

Geophysical Tests for Intermediate-Range Forces

DTIC Science & Technology

1993-11-01

34Feeble intermediate-range Gravitation, 1989, 154. Topics: AG,T, A forces from higher dimensions", Physical Review 60. Bell J. S., Perring J. K., ൝r...M., 134 Bell J. S., 60, 61 Coleman R., 389 Beltran-Lopez V., 359 Cabibbo N., 64 Coleman R. A ., 135 Bender P. L., 540 Calafiura P., 106 Cook A . H...of Zh. Eksp. Teor. Fiz., Selen M. A ., Shoemaker F. C., Smith A . J. S., 1985,88, 1946-1949.] Topics: SD,E,+ Blackmore E. W., Bryman D. A ., Felawka L

SELENE Translunar Trajectory Reconfiguration Plan Provided for the Case of Main Engine Anomaly

NASA Technical Reports Server (NTRS)

Kawakatsu, Yasuhiro

2007-01-01

In this paper, the reconfiguration of translunar trajectory in case of main engine anomaly is investigated. The objectives of the trajectory design are to reduce the excessive velocity at the Lunar encounter as well as to reduce the total required Delta-v to complete the sequence. 3-impulse Hohmann transfer based trajectory is adopted and possible trajectories are categorized under 2-body approximation. The solutions obtained are applied to more sophisticated models (3-body approximation and 4-body) and yields feasible trajectory.

The influence of different locations of sputter guns on the morphological and structural properties of Cu-In-Ga precursors and Cu(In,Ga)Se2 thin films

NASA Astrophysics Data System (ADS)

Wang, J.; Zhu, J.; He, Y. X.

2014-01-01

The influence of two different locations of sputter guns on the morphological and structural properties of Cu-In-Ga precursors and Cu(In,Ga)Se2 (CIGS) thin films was investigated. All the precursors contained cauliflower-like nodules, whereas smaller subnodules were observed on the background. All the precursors revealed apparent three-layered structures, and voids were observed at the CIGS/SLG interface of Sets 1 and 2 films rather than Set 3 film. EDS results indicated that all CIGS thin films were Cu-deficient. Based on the grazing incidence X-ray diffraction (GIXRD) patterns, as-selenized films showed peaks corresponding to the chalcopyrite-type CIGS structure. Depth-resolved Raman spectra showed the formation of a dominant CIGS phase inside the films for all the as-selenized samples investigated, and of an ordered vacancy compound (OVC) phase like Cu(In,Ga)3Se5 or Cu(In,Ga)2Se3.5 at the surface and/or CIGS/SLG interface region of Sets 2 and 3 films. No evidence was obtained on the presence of an OVC phase in Set 1 CIGS film, which may be speculated that long-time annealing is contributed to suppress the growth of OVC phases. The results of the present work suggest that the metallic precursors deposited with the upright-location sputter gun might be more appropriate to prepare CIGS thin films than those sputtered with the titled-location gun.

Open source software integrated into data services of Japanese planetary explorations

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Ishihara, Y.; Otake, H.; Imai, K.; Masuda, K.

2015-12-01

Scientific data obtained by Japanese scientific satellites and lunar and planetary explorations are archived in DARTS (Data ARchives and Transmission System). DARTS provides the data with a simple method such as HTTP directory listing for long-term preservation while DARTS tries to provide rich web applications for ease of access with modern web technologies based on open source software. This presentation showcases availability of open source software through our services. KADIAS is a web-based application to search, analyze, and obtain scientific data measured by SELENE(Kaguya), a Japanese lunar orbiter. KADIAS uses OpenLayers to display maps distributed from Web Map Service (WMS). As a WMS server, open source software MapServer is adopted. KAGUYA 3D GIS (KAGUYA 3D Moon NAVI) provides a virtual globe for the SELENE's data. The main purpose of this application is public outreach. NASA World Wind Java SDK is used to develop. C3 (Cross-Cutting Comparisons) is a tool to compare data from various observations and simulations. It uses Highcharts to draw graphs on web browsers. Flow is a tool to simulate a Field-Of-View of an instrument onboard a spacecraft. This tool itself is open source software developed by JAXA/ISAS, and the license is BSD 3-Caluse License. SPICE Toolkit is essential to compile FLOW. SPICE Toolkit is also open source software developed by NASA/JPL, and the website distributes many spacecrafts' data. Nowadays, open source software is an indispensable tool to integrate DARTS services.

Lentic, lotic, and sulfate-dependent waterborne selenium screening guidelines for freshwater systems.

PubMed

DeForest, David K; Brix, Kevin V; Elphick, James R; Rickwood, Carrie J; deBruyn, Adrian M H; Tear, Lucinda M; Gilron, Guy; Hughes, Sarah A; Adams, William J

2017-09-01

There is consensus that fish are the most sensitive aquatic organisms to selenium (Se) and that Se concentrations in fish tissue are the most reliable indicators of potential toxicity. Differences in Se speciation, biological productivity, Se concentration, and parameters that affect Se bioavailability (e.g., sulfate) may influence the relationship between Se concentrations in water and fish tissue. It is desirable to identify environmentally protective waterborne Se guidelines that, if not exceeded, reduce the need to directly measure Se concentrations in fish tissue. Three factors that should currently be considered in developing waterborne Se screening guidelines are 1) differences between lotic and lentic sites, 2) the influence of exposure concentration on Se partitioning among compartments, and 3) the influence of sulfate on selenate bioavailability. Colocated data sets of Se concentrations in 1) water and particulates, 2) particulates and invertebrates, and 3) invertebrates and fish tissue were compiled; and a quantile regression approach was used to derive waterborne Se screening guidelines. Use of a regression-based approach for describing relationships in Se concentrations between compartments reduces uncertainty associated with selection of partitioning factors that are generally not constant over ranges of exposure concentrations. Waterborne Se screening guidelines of 6.5 and 3.0 μg/L for lotic and lentic water bodies were derived, and a sulfate-based waterborne Se guideline equation for selenate-dominated lotic waters was also developed. Environ Toxicol Chem 2017;36:2503-2513. © 2017 SETAC. © 2017 SETAC.

Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.

PubMed

Qin, Hejie; Li, Jinxiang; Yang, Hongyi; Pan, Bingcai; Zhang, Weiming; Guan, Xiaohong

2017-05-02

Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe 0 was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe 0 core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe 0 to surface-located Se(VI).

Selenizing astragalus polysaccharide attenuates PCV2 replication promotion caused by oxidative stress through autophagy inhibition via PI3K/AKT activation.

PubMed

Liu, Dandan; Xu, Jing; Qian, Gang; Hamid, Mohammed; Gan, Fang; Chen, Xingxiang; Huang, Kehe

2018-03-01

Our previous studies have shown that oxidative stress could promote the porcine circovirus type 2 (PCV2) replication, and astragalus polysaccharide (APS)/selenium could suppress PCV2 replication. However, whether selenizing astragalus polysaccharide (sAPS) provides protection against oxidative stress-induced PCV2 replication promotion and the mechanism involved remain unclear. The present study aimed to explore the mechanism of the PCV2 replication promotion induced by oxidative stress and a novel pharmacotherapeutic approach involving the regulation of autophagy of sAPS. Our results showed that H 2 O 2 promoted PCV2 replication via enhancing autophagy by using 3-methyladenine (3-MA) and autophagy-related gene 5 (ATG5) knockdown. Sodium selenite, APS, the mixture of sodium selenite and APS, and sAPS significantly inhibited H 2 O 2 -induced PCV2 replication promotion, respectively. Among these, sAPS exerted maximal inhibitory effect. sAPS could also significantly inhibit autophagy activated by H 2 O 2 and increase the Akt and mTOR phosphorylation. Moreover, LY294002, the specific phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) inhibitor, significantly alleviated the effects of sAPS on autophagy and PCV2 replication. Taken together, we conclude that H 2 O 2 promotes PCV2 replication by inducing autophagy and sAPS attenuates the PCV2 replication promotion through autophagy inhibition via PI3K/AKT activation. Copyright © 2017 Elsevier B.V. All rights reserved.

Se(VI) Reduction and the Precipitation of Se(0) Precipitation by the Facultative Bacterium Enterobacter Cloacae SLD1a-1 is Regulated by FNR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yee,N.; Ma, J.; Dalia, A.

2007-01-01

The fate of selenium in the environment is controlled, in part, by microbial selenium oxyanion reduction and Se(0) precipitation. In this study, we identified a genetic regulator that controls selenate reductase activity in the Se-reducing bacterium Enterobacter cloacae SLD1a-1. Heterologous expression of the global anaerobic regulatory gene fnr (fumarate nitrate reduction regulator) from E. cloacae in the non-Se-reducing strain Escherichia coli S17-1 activated the ability to reduce Se(VI) and precipitate insoluble Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at rates similar to those for E. cloacae, with first-order reaction constants of k = 2.07more » x 10{sup -2} h{sup -1} and k = 3.36 x 10{sup -2} h{sup -1}, respectively, and produced elemental selenium particles with identical morphologies and short-range atomic orders. Mutation of the fnr gene in E. cloacae SLD1a-1 resulted in derivative strains that were deficient in selenate reductase activity and unable to precipitate elemental selenium. Complementation by the wild-type fnr sequence restored the ability of mutant strains to reduce Se(VI). Our findings suggest that Se(VI) reduction and the precipitation of Se(0) by facultative anaerobes are regulated by oxygen-sensing transcription factors and occur under suboxic conditions.« less

Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: II. Kinetic and reactive transport modeling.

PubMed

Tabelin, Carlito Baltazar; Sasaki, Ryosuke; Igarashi, Toshifumi; Park, Ilhwan; Tamoto, Shuichi; Arima, Takahiko; Ito, Mayumi; Hiroyoshi, Naoki

2017-12-01

Predicting the fates of arsenic (As) and selenium (Se) in natural geologic media like rocks and soils necessitates the understanding of how their various oxyanionic species behave and migrate under dynamic conditions. In this study, geochemical factors and processes crucial in the leaching and transport of arsenite (As III ), arsenate (As V ), selenite (Se IV ) and selenate (Se VI ) in tunnel-excavated rocks of marine origin were investigated using microscopic/extraction techniques, column experiments, dissolution-precipitation kinetics and one-dimensional reactive transport modeling. The results showed that evaporite salts were important because aside from containing As and Se, they played crucial roles in the evolution of pH and concentrations of coexisting ions, both of which had strong effects on adsorption-desorption reactions of As and Se species with iron oxyhydroxide minerals/phases. The observed leaching trends of As V , As III , Se IV and Se VI were satisfactorily simulated by one-dimensional reactive transport models, which predict that preferential adsorptions of As V and Se IV were magnified by geochemical changes in the columns due to water flow. Moreover, our results showed that migrations of As III , Se IV and Se VI could be predicted adequately by 1D solute transport with simple activity-K' d approach, but surface complexation was more reliable to simulate adsorption-desorption behavior of As V . Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of High-pH and High-Ionic-Strength Groundwater on Iodide, Pertechnetate, and Selenate Sorption to Hanford Sediments: Final Report for Subtask 3a

DOE Office of Scientific and Technical Information (OSTI.GOV)

DI Kaplan; KE Parker; RD Orr

1998-10-14

As part of the Immobilized Low-Activity Waste-Performance Assessment three experiments were conducted to evaluate the effect of the expected near-field chemistry on the sorption of iodide, selenate, and pertechnetate onto a sediment obtained from the Hanford Site. These experiments were performed in fiscal year 1998 at the Pacific Northwest National Laboratory.' During these experiments, attention was directed at the identification of the chemical mechanisms controlling the sorption processes to provide technical defensibility for the selection of the distribution coefficients (IQ to be used in the remainder of the performance assessment. It was found, during the conduct of the experiments, thatmore » selenium and technetium I&s increased as ionic strength increased. The cause for this is most likely to be that the higher ionic strength caused the double layer around the particles to decrease, thereby permitting greater interaction with the mineral surfaces. Further, the pH level had an effect on the sorption of these anions. These are the first-ever experiments conducted with Hanford Site sediment in which the IQ were measured as a function of ionic strength and pH. Overall, the observed trends were consistent with more generalized geochemical principles. One of the most important contributions of these experiments was that they quantified the & changes induced by variations in ionic strength and pH that are expected to exist in the near field.« less

Effects of supplementation of fertilizers on human selenium status in Finland.

PubMed

Aro, A; Alfthan, G; Varo, P

1995-03-01

The Se concentration of foods can be increased by supplementing fertilizers with soluble Se compounds. In Finland the availability of soil Se for plants is poor owing to the relatively low Se concentration, low pH and high iron content of the soil. Since 1984 multimineral fertilizers have been supplemented with Se (16 mg kg-1 to fertilizers for grain production and 6 mg kg-1 to those for fodder production) in the form of sodium selenate. Within two years a three-fold increase of mean Se intake was observed. The supplementation affected the Se content of all major food groups with the exception of fish. The concomitant human serum Se concentration increased by 70%. In 1990 the amount of Se that was supplemented was reduced to 6 mg kg-1 for all fertilizers. This reduced the mean Se intake by 30% and the serum Se concentration decreased by 25% from the highest levels observed in 1989. Plants take up part of the supplemented selenate and transform it into organic Se compounds, mainly selenomethionine. This affects human nutrition by increasing the Se content of foods of both animal and vegetable origin. According to data obtained in Finland, supplementation of fertilizers with Se is a safe and effective means of increasing the Se intake of both animals and humans that is feasible in countries with relatively uniform geochemical conditions. This kind of intervention requires careful monitoring of the effects on both animal and human nutrition and the environment.

Study of Pitch Attitude Estimation Using a High-Definition TV (HDTV) Camera on the Japanese Lunar Explorer SELENE (KAGUYA)

NASA Astrophysics Data System (ADS)

Sobue, Shinichi; Yamazaki, Junichi; Matsumoto, Shuichi; Konishi, Hisahiro; Maejima, Hironori; Sasaki, Susumu; Kato, Manabu; Mitsuhashi, Seiji; Tachino, Junichi

The lunar explorer SELENE (also called KAGUYA) carried thirteen scientific mission instruments to reveal the origin and evolution of Moon and to investigate the possible future utilization of Moon. In addition to the scientific instruments, a high-definition TV (HDTV) camera provided by the Japan Broadcasting Corporation (NHK) was carried on KAGUYA to promote public outreach. We usually use housekeeping telemetry data to derive the satellite attitude along with orbital determination and propagated information. However, it takes time to derive this information, since orbital determination and propagation calculation require the use of the orbital model. When a malfunction of the KAGUYA reaction wheel occurred, we could not have correct attitude information. This means that we don’t have a correct orbital determination in timely fashion. However, when we checked HDTV movies, we found that horizon information on the lunar surface derived from HDTV moving images as a horizon sensor was very useful for the detection of the attitude of KAGUYA. We then compared this information with the attitude information derived from orbital telemetry to validate the accuracy of the HDTV derived estimation. As a result of this comparison, there are good pitch attitude estimation using HDTV derived estimation and we could estimate the pitch angle change during the KAGUYA mission operation simplify and quickly. In this study, we show the usefulness of this HDTV camera as a horizon sensor.

Inorganic speciation analysis of selenium by ion chromatography-inductively coupled plasma-mass spectrometry and its application to effluents from a petroleum refinery

NASA Astrophysics Data System (ADS)

Miekeley, Norbert; Pereira, Rogério C.; Casartelli, Evelton A.; Almeida, Ana C.; de F. B. Carvalho, Maria

2005-06-01

A new method for the speciation analysis of selenite (Se-IV), selenate (Se-VI), and selenocyanate (SeCN -) is described and first results are presented on the distribution of these species in wastewater samples from a Brazilian oil refinery plant. The method is based on the ion chromatographic separation of these species followed by on-line detection of 77Se, 78Se, and 82Se using quadrupole inductively coupled plasma-mass spectrometry (ICPMS). The system employed consisted of a HPLC pump equipped with a manual syringe loading injector, and an anion exchange column (Metrosep A Supp1), the latter interfaced with the ICPMS via a concentric nebulizer-cyclonic spray chamber sample introduction device. Several eluents already described in the literature for the speciation analysis of inorganic selenium were tested, permitting in most cases a good separation of Se(IV) and Se(VI), however, resulting all in very long residence times (> 30 min) and associated peak broadening for the SeCN - ion. This drawback could be effectively avoided by using as the mobile phase a solution of cyanuric acid (3 mmol L -1), modified with acetonitrile (2% v/v) and percchlorate acid (2.5 mmol L -1). Typical retention times (s) for the three analyte species were: selenite (210) < selenate (250) < selenocyanate (450). Repeatabilities in peak position were better than 1% and in peak area evaluation about 3%. Absolute limits of detection (in ng) for these species using an ELAN 5000 instrument and a 500-μL sample injection loop are 0.04, 0.05 and 0.09, respectively. No certified reference materials were available for this study, however, results on spiked wastewater samples showed acceptable recoveries (80-110%) and repeatabilities (RSD < 5%), thus validating this method for its intended purpose. Once optimized, the method was applied to wastewater samples from an oil refinery plant. In all samples until now analyzed, selenocyanate was by far the most abundant selenium species reaching concentrations of up to 90 μg L -1. Selenite was detected only in one sample and selenate could not identified in any of the samples analyzed. Total concentrations of selenium in most samples, assessed by hydride generation ICPMS and by solution nebulization inductively coupled plasma optical emission spectrometry (ICPOES), exceeded those obtained from speciation analysis, indicating the presence of other selenium species not observed by the here used methodology.

Effect of Long Selenization Time on Co Films under a Low Temperature of 300 °C to Synthesize a Nanostructure CoSe2 and Optical Properties

NASA Astrophysics Data System (ADS)

Wu, Po-Feng; Shi, Jen-Bin; Cheng, Bo-Ci; Wu, Cheng-Han; Lee, Hsuan-Wei; Lin, Hsien-Sheng; Cheng, Fu-Chou; Chen, Kuan-Ping

2018-05-01

This work investigates a simple and non-toxic method to transform pre-deposited amorphous Co film into CoSe2 films at a fixed, low temperature of 300 °C. Single CoSe2-phase films having good crystallinity were obtained at a selenisation time ≧ 24 hours. A nanostructure CoSe2 having two different nano-morphological layers was observed. The CoSe2 films (72 hours) observed a large absorption and a direct band gap.

High incidence of selenite-resistant bacteria from a site polluted with selenium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, G.A. Jr.; Giddings, T.H.; DeBrine, P.

1987-01-01

The level of selenium-resistant bacteria in water, algal mats, and sediment from Kesterson reservoir, Calif., a site with known selenium pollution, was compared with that in nearby Volta reservoir, a site with low selenium levels. A high percentage (>50%) of all isolates from the Kesterson samples were resistant to 10 mM selenite. In contrast, only a small percentage of the Volta isolates were resistant to this level of selenite. The identity of some selenite-resistant isolates and MICs of selenite, selenate, arsenite, arsenate, tellurite, and tellurate were determined.

Synthesis of carrier-free tritium-labeled queen bee pheromone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Webster, F.X.; Prestwich, G.D.

A short synthesis of (4,5-/sup 3/H/sub 2/) (E)-9-oxo-2-decenoic acid (ODA), a high-specific-activity tritium-containing isotopomer of the queen bee pheromone, is described. Catalytic tritiation of the ketal of ethyl 9-oxo-4-decenoate introduces tritium into two positions, one of which is completely unactivated. Subsequent transformation by selenation, oxidation, and hydrolysis affords the labeled 9-ODA at >60 Ci/mmol. The material is suitable for biochemical studies of binding and catabolism in ovarian, antennal, and other target tissues.

Growth of Cu2ZnSnSe4 Film under Controllable Se Vapor Composition and Impact of Low Cu Content on Solar Cell Efficiency.

PubMed

Li, Jianjun; Wang, Hongxia; Wu, Li; Chen, Cheng; Zhou, Zhiqiang; Liu, Fangfang; Sun, Yun; Han, Junbo; Zhang, Yi

2016-04-27

It is a challenge to fabricate high quality Cu2ZnSnSe4 (CZTSe) film with low Cu content (Cu/(Zn + Sn) < 0.8). In this work, the growth mechanisms of CZTSe films under different Se vapor composition are investigated by DC-sputtering and a postselenization approach. The composition of Se vapor has important influence on the compactability of the films and the diffusion of elements in the CZTSe films. By adjusting the composition of Se vapor during the selenization process, an optimized two step selenization process is proposed and highly crystallized CZTSe film with low Cu content (Cu/(Zn + Sn) = 0.75) is obtained. Further study of the effect of Cu content on the morphology and photovoltaic performance of the corresponding CZTSe solar cells has shown that the roughness of the CZTSe absorber film increases when Cu content decreases. As a consequence, the reflection loss of CZTSe solar cells reduces dramatically and the short circuit current density of the cells improve from 34.7 mA/cm(2) for Cu/(Zn + Sn) = 0.88 to 38.5 mA/cm(2) for Cu/(Zn + Sn) = 0.75. In addition, the CZTSe solar cells with low Cu content show longer minority carrier lifetime and higher open circuit voltage than the high Cu content devices. A champion performance CZTSe solar cell with 10.4% efficiency is fabricated with Cu/(Zn + Sn) = 0.75 in the CZTSe film without antireflection coating.

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food.

PubMed

Hart, D J; Fairweather-Tait, S J; Broadley, M R; Dickinson, S J; Foot, I; Knott, P; McGrath, S P; Mowat, H; Norman, K; Scott, P R; Stroud, J L; Tucker, M; White, P J; Zhao, F J; Hurst, R

2011-06-15

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1μg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium. Copyright © 2010 Elsevier Ltd. All rights reserved.

Edge-selenated graphene nanoplatelets as durable metal-free catalysts for iodine reduction reaction in dye-sensitized solar cells

PubMed Central

Ju, Myung Jong; Jeon, In-Yup; Kim, Hong Mo; Choi, Ji Il; Jung, Sun-Min; Seo, Jeong-Min; Choi, In Taek; Kang, Sung Ho; Kim, Han Seul; Noh, Min Jong; Lee, Jae-Joon; Jeong, Hu Young; Kim, Hwan Kyu; Kim, Yong-Hoon; Baek, Jong-Beom

2016-01-01

Metal-free carbon-based electrocatalysts for dye-sensitized solar cells (DSSCs) are sufficiently active in Co(II)/Co(III) electrolytes but are not satisfactory in the most commonly used iodide/triiodide (I−/I3−) electrolytes. Thus, developing active and stable metal-free electrocatalysts in both electrolytes is one of the most important issues in DSSC research. We report the synthesis of edge-selenated graphene nanoplatelets (SeGnPs) prepared by a simple mechanochemical reaction between graphite and selenium (Se) powders, and their application to the counter electrode (CE) for DSSCs in both I−/I3− and Co(II)/Co(III) electrolytes. The edge-selective doping and the preservation of the pristine graphene basal plane in the SeGnPs were confirmed by various analytical techniques, including atomic-resolution transmission electron microscopy. Tested as the DSSC CE in both Co(bpy)32+/3+ (bpy = 2,2′-bipyridine) and I−/I3− electrolytes, the SeGnP-CEs exhibited outstanding electrocatalytic performance with ultimately high stability. The SeGnP-CE–based DSSCs displayed a higher photovoltaic performance than did the Pt-CE–based DSSCs in both SM315 sensitizer with Co(bpy)32+/3+ and N719 sensitizer with I−/I3− electrolytes. Furthermore, the I3− reduction mechanism, which has not been fully understood in carbon-based CE materials to date, was clarified by an electrochemical kinetics study combined with density functional theory and nonequilibrium Green’s function calculations. PMID:27386557

A bacterial process for selenium nanosphere assembly

PubMed Central

Debieux, Charles M.; Dridge, Elizabeth J.; Mueller, Claudia M.; Splatt, Peter; Paszkiewicz, Konrad; Knight, Iona; Florance, Hannah; Love, John; Titball, Richard W.; Lewis, Richard J.; Richardson, David J.; Butler, Clive S.

2011-01-01

During selenate respiration by Thauera selenatis, the reduction of selenate results in the formation of intracellular selenium (Se) deposits that are ultimately secreted as Se nanospheres of approximately 150 nm in diameter. We report that the Se nanospheres are associated with a protein of approximately 95 kDa. Subsequent experiments to investigate the expression and secretion profile of this protein have demonstrated that it is up-regulated and secreted in response to increasing selenite concentrations. The protein was purified from Se nanospheres, and peptide fragments from a tryptic digest were used to identify the gene in the draft T. selenatis genome. A matched open reading frame was located, encoding a protein with a calculated mass of 94.5 kDa. N-terminal sequence analysis of the mature protein revealed no cleavable signal peptide, suggesting that the protein is exported directly from the cytoplasm. The protein has been called Se factor A (SefA), and homologues of known function have not been reported previously. The sefA gene was cloned and expressed in Escherichia coli, and the recombinant His-tagged SefA purified. In vivo experiments demonstrate that SefA forms larger (approximately 300 nm) Se nanospheres in E. coli when treated with selenite, and these are retained within the cell. In vitro assays demonstrate that the formation of Se nanospheres upon the reduction of selenite by glutathione are stabilized by the presence of SefA. The role of SefA in selenium nanosphere assembly has potential for exploitation in bionanomaterial fabrication. PMID:21808043

Toxicity and oxidative stress of different forms of organic selenium and dietary protein in mallard ducklings

USGS Publications Warehouse

Hoffman, D.J.; Heinz, G.H.; LeCaptain, L.J.; Eisemann, J.D.; Pendleton, G.W.

1996-01-01

Concentrations of over 100 ppm (mg/kg) selenium (Se) have been found in aquatic plants and insects associated with irrigation drainwater and toxicity to fish and wildlife. Composition of diet for wild ducklings may vary in selenium-contaminated environments. Earlier studies have compared toxicities and oxidative stress of Se as selenite to those of seleno-DL-methionine (DL) in mallards (Anas platyrhynchos). This study compares DL, seleno-L-methionine (L), selenized yeast (Y) and selenized wheat (W). Day-old mallard ducklings received an untreated diet (controls) containing 75% wheat (22% protein) or the same diet containing 15 or 30 ppm Se in the above forms except for 30 ppm Se as W. After 2 weeks blood and liver samples were collected for biochemical assays and Se analysis. All forms of selenium caused significant increases in plasma and hepatic glutathione peroxidase activities. Se as L at 30 ppm in the diet was the most toxic form, resulting in high mortality (64%) and impaired growth (>50%) in survivors and the greatest increase in ratio of oxidized to reduced hepatic glutathione (GSH). Se as both L and DL decreased the concentrations of hepatic GSH and total thiols. Se as Y accumulated the least in liver (approximately 50% of other forms) and had less effect on GSH and total thiols. In a second experiment, in which the basal diet was a commercial duck feed (22 % protein), survival was not affected by 30 ppm Se as DL, L, or Y and oxidative effects on GSH metabolism were less pronounced than with the wheat diet.

Fullerene-like MoSe2 nanoparticles-embedded CNT balls with excellent structural stability for highly reversible sodium-ion storage.

PubMed

Choi, Seung Ho; Kang, Yun Chan

2016-02-21

Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250(th) discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g(-1), respectively, at a high current density of 1.0 A g(-1), and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10(th) discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g(-1) at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g(-1), respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls.

Chemical and structural evolution in the Th-SeO3(2-)/SeO4(2-) system: from simple selenites to cluster-based selenate compounds.

PubMed

Xiao, Bin; Langer, Eike; Dellen, Jakob; Schlenz, Hartmut; Bosbach, Dirk; Suleimanov, Evgeny V; Alekseev, Evgeny V

2015-03-16

While extensive success has been gained in the structural chemistry of the U-Se system, the synthesis and characterization of Th-based Se structures are widely unexplored. Here, four new Th-Se compounds, α-Th(SeO3)2, β-Th(SeO3)2, Th(Se2O5)2, and Th3O2(OH)2(SeO4)3, have been obtained from mild hydrothermal or low-temperature (180-220 °C) flux conditions and were subsequently structurally and spectroscopically characterized. The crystal structures of α-Th(SeO3)2 and β-Th(SeO3)2 are based on ThO8 and SeO3 polyhedra, respectively, featuring a three-dimensional (3D) network with selenite anions filling in the Th channels along the a axis. Th(Se2O5)2 is a 3D framework composed of isolated ThO8 polyhedra interconnected by [Se2O5](2-) dimers. Th3O2(OH)2(SeO4)3 is also a 3D framework constructed by octahedral hexathorium clusters [Th6(μ3-O)4(μ3-OH)4](12+), which are interlinked by selenate groups SeO4(2-). The positions of the vibrational modes associated with both Se(IV)O3(2-) and Se(VI)O4(2-) units, respectively, were determined for four compounds, and the Raman spectra of α- and β-Th(SeO3)2 are compared and discussed in detail.

The response of broccoli (Brassica oleracea convar. italica) varieties on foliar application of selenium: uptake, translocation, and speciation.

PubMed

Šindelářová, Kristýna; Száková, Jiřina; Tremlová, Jana; Mestek, Oto; Praus, Lukáš; Kaňa, Antonín; Najmanová, Jana; Tlustoš, Pavel

2015-01-01

A model small-scale field experiment was set up to investigate selenium (Se) uptake by four different varieties of broccoli plants, as well as the effect of Se foliar application on the uptake of essential elements for plants calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), sulfur (S), and zinc (Zn). Foliar application of sodium selenate (Na2SeO4) was carried out at two rates (25 and 50 g Se/ha), and an untreated control variant was included. Analyses of individual parts of broccoli were performed, whereby it was found that Se in the plant accumulates mainly in the flower heads and slightly less in the leaves, stems, and roots, regardless of the Se rate and broccoli variety. In most cases, there was a statistically significant increase of Se content in all parts of the plant, while there was no confirmed systematic influence of the addition of Se on the changing intake of other monitored elements. Selenization of broccoli leads to an effective increase in the Se content at a rate of 25 g/ha, whereas the higher rate did not result in a substantial increase of Se content compared to the lower rate in all varieties. Therefore, the rate of 25 g/ha can be recommended as effective to produce broccoli with an increased Se content suitable for consumption. Moreover, Se application resulted in an adequate increase of the main organic compounds of Se, such as selenocystine (SeCys2), selenomethionine (SeMet), and Se-methylselenocysteine (Se-MeSeCys).

Synthesis, Deposition, and Microstructure Development of Thin Films Formed by Sulfidation and Selenization of Copper Zinc Tin Sulfide Nanocrystals

NASA Astrophysics Data System (ADS)

Chernomordik, Boris David

Significant reduction in greenhouse gas emission and pollution associated with the global power demand can be accomplished by supplying tens-of-terawatts of power with solar cell technologies. No one solar cell material currently on the market is poised to meet this challenge due to issues such as manufacturing cost, material shortage, or material toxicity. For this reason, there is increasing interest in efficient light-absorbing materials that are comprised of abundant and non-toxic elements for thin film solar cell. Among these materials are copper zinc tin sulfide (Cu2ZnSnS4, or CZTS), copper zinc tin selenide (Cu2ZnSnSe4, or CZTSe), and copper zinc tin sulfoselenide alloys [Cu2ZnSn(SxSe1-x )4, or CZTSSe]. Laboratory power conversion efficiencies of CZTSSe-based solar cells have risen to almost 13% in less than three decades of research. Meeting the terawatt challenge will also require low cost fabrication. CZTSSe thin films from annealed colloidal nanocrystal coatings is an example of solution-based methods that can reduce manufacturing costs through advantages such as high throughput, high material utilization, and low capital expenses. The film microstructure and grain size affects the solar cell performance. To realize low cost commercial production and high efficiencies of CZTSSe-based solar cells, it is necessary to understand the fundamental factors that affect crystal growth and microstructure evolution during CZTSSe annealing. Cu2ZnSnS4 (CZTS) nanocrystals were synthesized via thermolysis of single-source cation and sulfur precursors copper, zinc and tin diethyldithiocarbamates. The average nanocrystal size could be tuned between 2 nm and 40 nm, by varying the synthesis temperature between 150 °C and 340 °C. The synthesis is rapid and is completed in less than 10 minutes. Characterization by X-ray diffraction, Raman spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy confirm that the nanocrystals are nominally stoichiometric kesterite CZTS. The ~2 nm nanocrystals synthesized at 150 °C exhibit quantum confinement, with a band gap of 1.67 eV. Larger nanocrystals have the expected bulk CZTS band gap of 1.5 eV. Several micron thick films deposited by drop casting colloidal dispersions of ~40 nm CZTS nanocrystals were crack-free, while those cast using 5 nm nanocrystals had micron-scale cracks. We showed the applicability of these nanocrystal coatings for thin film solar cells by demonstrating a CZTS thin film solar cell using coatings annealed in a sulfur atmosphere. We conducted a systematic study of the factors controlling crystal growth and microstructure development during sulfidation annealing of films cast from colloidal dispersions of CZTS nanocrystals. The film microstructure is controlled by concurrent normal and abnormal grain growth. At 600 °C to 800 °C and low sulfur pressures (50 Torr), abnormal CZTS grains up to 10 microm in size grow on the surface of the CZTS nanocrystal film via transport of material from the nanocrystals to the abnormal grains. Meanwhile, the nanocrystals coarsen, sinter, and undergo normal grain growth. The driving force for abnormal grain growth is the reduction in total energy associated with the high surface area nanocrystals. The eventual coarsening of the CZTS nanocrystals reduces the driving force for abnormal crystal growth. Increasing the sulfur pressure by an order of magnitude to 500 Torr accelerates both normal and abnormal crystal growth though sufficient acceleration of the former eventually reduces the latter by reducing the driving force for abnormal grain growth. For example, at high temperatures (700-800 oC) and sulfur pressures (500 Torr) normal grains quickly grow to ~500 nm which significantly reduces abnormal grain growth. The use of soda lime glass as the substrate, instead of quartz, accelerates normal grain growth. Normal grains grow to ~500 nm at lower temperatures and sulfur pressures (i.e., 600 °C and 50 Torr) than those required to grow the same size grains on quartz (700 °C and 500 Torr). Moreover, carbon is removed by volatilization from films where normal crystal growth is fast. There are significant differences in the chemistry and in the thermodynamics involved during selenization and sulfidation of CZTS colloidal nanocrystal coatings to form CZTSSe or CZTS thin films, respectively. To understand these differences, the roles of vapor pressure, annealing temperature, and heating rate in the formation of different microstructures of CZTSSe films were investigated. Selenization produced a bi-layer microstructure where a large CZTSSe-crystal layer grew on top of a nanocrystalline carbon-rich bottom layer. Differences in the chemistry of carbon and selenium and that of carbon and sulfur account for this segregation of carbon during selenization. For example, CSe 2 and CS2, both volatile species, may form as a result of chalcogen interactions with carbon during annealing. Unlike CS2, however, CSe2 may readily polymerize at room temperature and one atmosphere. Carbon segregation may be occurring only during selenization due to the formation of a Cu-Se polymer [i.e., (CSe 2-x)] within the nanocrystal film. The (CSe2-x) inhibits sintering of nanocrystals in the bottom layer. Additionally, a fast heating rate results in temperature variations that lead to transient condensation of selenium on the film. This is observed only during selenization because the equilibrium vapor pressure of selenium is lower than that of sulfur. The presence of liquid selenium during sintering accelerates coarsening and densification of the normal crystal layer (no abnormal crystal layer) by liquid phase sintering. Carbon segregation does not occur where liquid selenium was present.

Unprecedented Zipangu Underworld of the Moon Exploration (UZUME)

NASA Astrophysics Data System (ADS)

Haruyama, J.; Kawano, I.; Kubota, T.; Otsuki, M.; Kato, H.; Nishibori, T.; Iwata, T.; Yamamoto, Y.; Nagamatsu, A.; Shimada, K.; Ishihara, Y.; Hasenaka, T.; Morota, T.; Nishino, M. N.; Hashizume, K.; Saiki, K.; Shirao, M.; Komatsu, G.; Hasebe, N.; Shimizu, H.; Miyamoto, H.; Kobayashi, K.; Yokobori, S.; Michikami, T.; Yamamoto, S.; Yokota, Y.; Arisumi, H.; Ishigami, G.; Furutani, K.; Michikawa, Y.

2014-04-01

On the Moon, three huge vertical holes (several tens to a hundred meters in diameter and depth) were discovered in SELENE (nicknamed Kaguya) Terrain Camera data of 10 m pixel resolution. These holes are probably skylights of underground large caverns such as lava tubes, or magma chambers. The huge holes and their associated subsurface caverns are among the most important future exploration targets from the viewpoint of constructing lunar bases and many scientific aspects. We are now planning to explore the caverns through the skylight holes. We name the project as UZUME (Unprecedented Zipangu (Japan) Underworld of the Moon Exploration).

10.3%-efficient submicron-thick Cu(In,Ga)Se2 solar cells with absorber fabricated by sputtering In2Se3, CuGaSe2 and Cu2Se targets

NASA Astrophysics Data System (ADS)

Peng, Xiao; Zhao, Ming; Zhuang, Daming; Sun, Rujun; Zhang, Leng; Wei, Yaowei; Lv, Xunyan; Wu, Yixuan; Ren, Guoan

2018-06-01

We reported a new method to fabricate submicron-thick CIGS with smooth surface by sputtering In2Se3, CuGaSe2 and Cu2Se targets with post-selenization. The influence of gallium content on the properties of CIGS thin film was evaluated by the crystallinity and the cells performance. The most suitable value of Ga content in our submicron-thick CIGS is 0.32 and cells based on it demonstrated the highest efficiency of 10.3%.

New Gel-Like Polymers as Selective Weak-Base Anion Exchangers

PubMed Central

Gierczyk, Błażej; Cegłowski, Michał; Zalas, Maciej

2015-01-01

A group of new anion exchangers, based on polyamine podands and of excellent ion-binding capacity, were synthesized. The materials were obtained in reactions between various poly(ethyleneamines) with glycidyl derivatives of cyclotetrasiloxane. The final polymeric, strongly cross-linked materials form gel-like solids. Their structures and interactions with anions adsorbed were studied by spectroscopic methods (CP-MAS NMR, FR-IR, UV-Vis). The sorption isotherms and kinetic parameters were determined for 29 anions. Materials studied show high ion capacity and selectivity towards some important anions, e.g., selenate(VI) or perrhenate. PMID:25946220

Method for crater detection from digital topography data: interpolation based improvement and application to Lunar SELENE LALT data

NASA Astrophysics Data System (ADS)

Salamunićcar, Goran; Lončarić, Sven

Crater detection algorithms (CDAs) are an important subject of recent scientific research, as evident from the numerous recent publications in the field [ASR, 42 (1), 6-19]. In our previous work: (1) all the craters from the major currently available manually assembled catalogues have been merged into the catalogue with 57633 known Martian impact-craters [PSS, 56 (15), 1992-2008]; and (2) the CDA (developed to search for still uncatalogued impact-craters using 1/128° MOLA data) has been used to extend GT-57633 catalogue with 57592 additional craters resulting in GT-115225 catalog [GRS, 48 (5), in press, doi:10.1109/TGRS.2009.2037750]. On the other hand, the most complete catalog for Moon is the Morphological catalog of Lunar craters [edited by V. V. Shevchenko], which includes information on 14923 craters larger than 10km, visible on the lunar nearside and farside. This was the main motivation for application of our CDA to newly available Lunar SELENE LALT data. However, one of the main differences between MOLA and LALT data is the highest available resolution, wherein MOLA is available in 1/128° and LALT in 1/16° . The consequence is that only the largest craters can be detected using LALT dataset. However, this is still an excellent opportunity for further work on CDA in order to prepare it for forthcoming LRO LOLA data (which is expected to be in even better resolution than MOLA). The importance is in the fact that morphologically Martian and Lunar craters are not the same. Therefore, it is important to use the dataset for Moon in order to work on the CDA which is meant for detection of Lunar craters as well. In order to overcome the problem of currently available topography data in low resolution only, we particularly concentrated our work on the CDA's capability to detect very small craters relative to available dataset (up to the extreme case wherein the radius is as small as only two pixels). For this purpose, we improved the previous CDA with a new algorithm for sub-pixel interpolation of elevation samples, before subsequent computations. For elevation samples on larger distances from the crater's center, linear interpolation was used in order to speed-up the computations. For samples closer to the crater's center, the elevation value at the crater's center and relative sub-pixel distance to the selected elevation sample is additionally taken into account. The purpose is to compute the most realistic values for estimated elevation at a selected point. The results are, according to the initial visual evaluation, that numerous craters were successfully detected using SELENE LALT data.

Acute exposure to selenium disrupts associative conditioning and long-term memory recall in honey bees (Apis mellifera).

PubMed

Burden, Christina M; Elmore, Christopher; Hladun, Kristen R; Trumble, John T; Smith, Brian H

2016-05-01

A plethora of toxic compounds - including pesticides, heavy metals, and metalloids - have been detected in honey bees (Apis mellifera) and their colonies. One such compound is selenium, which bees are exposed to by consuming nectar and pollen from flowers grown in contaminated areas. Though selenium is lethal at high concentrations, sublethal exposure may also impair honey bees' ability to function normally. Examining the effect of selenium exposure on learning and memory provides a sensitive assay with which to identify sublethal effects on honey bee health and behavior. To determine whether sublethal selenium exposure causes learning and memory deficits, we used proboscis extension reflex conditioning coupled with recall tests 30min and 24h post-conditioning. We exposed forager honey bees to a single sublethal dose of selenium, and 3h later we used an olfactory conditioning assay to train the bees to discriminate between one odor associated with sucrose-reinforcement and a second unreinforced odor. Following conditioning we tested short- and long-term recall of the task. Acute exposure to as little as 1.8ng of an inorganic form of selenium (sodium selenate) before conditioning caused a reduction in behavioral performance during conditioning. And, exposure to 18ng of either an inorganic form (sodium selenate) or an organic form (methylseleno-l-cysteine) of selenium caused a reduction in the bees' performance during the long-term recall test. These concentrations of selenium are lower than those found in the nectar of plants grown in selenium-contaminated soil, indicating that even low-grade selenium toxicity produces significant learning and memory impairments. This may reduce foragers' ability to effectively gather resources for the colony or nurse bees' ability to care for and maintain a healthy colony. Copyright © 2016. Published by Elsevier Inc.

"Omics" of Selenium Biology: A Prospective Study of Plasma Proteome Network Before and After Selenized-Yeast Supplementation in Healthy Men.

PubMed

Sinha, Indu; Karagoz, Kubra; Fogle, Rachel L; Hollenbeak, Christopher S; Zea, Arnold H; Arga, Kazim Y; Stanley, Anne E; Hawkes, Wayne C; Sinha, Raghu

2016-04-01

Low selenium levels have been linked to a higher incidence of cancer and other diseases, including Keshan, Chagas, and Kashin-Beck, and insulin resistance. Additionally, muscle and cardiovascular disorders, immune dysfunction, cancer, neurological disorders, and endocrine function have been associated with mutations in genes encoding for selenoproteins. Selenium biology is complex, and a systems biology approach to study global metabolomics, genomics, and/or proteomics may provide important clues to examining selenium-responsive markers in circulation. In the current investigation, we applied a global proteomics approach on plasma samples collected from a previously conducted, double-blinded placebo controlled clinical study, where men were supplemented with selenized-yeast (Se-Yeast; 300 μg/day, 3.8 μmol/day) or placebo-yeast for 48 weeks. Proteomic analysis was performed by iTRAQ on 8 plasma samples from each arm at baseline and 48 weeks. A total of 161 plasma proteins were identified in both arms. Twenty-two proteins were significantly altered following Se-Yeast supplementation and thirteen proteins were significantly changed after placebo-yeast supplementation in healthy men. The differentially expressed proteins were involved in complement and coagulation pathways, immune functions, lipid metabolism, and insulin resistance. Reconstruction and analysis of protein-protein interaction network around selected proteins revealed several hub proteins. One of the interactions suggested by our analysis, PHLD-APOA4, which is involved in insulin resistance, was subsequently validated by Western blot analysis. Our systems approach illustrates a viable platform for investigating responsive proteomic profile in 'before and after' condition following Se-Yeast supplementation. The nature of proteins identified suggests that selenium may play an important role in complement and coagulation pathways, and insulin resistance.

NCI calculations for understanding a physical phase transition in (C6H14N2)[Mn(H2O)6](SeO4)2

NASA Astrophysics Data System (ADS)

Naïli, Houcine; François, Michel; Norquist, Alexander J.; Rekik, Walid

2017-12-01

An organically templated manganese selenate, (C6H14N2)[Mn(H2O)6](SeO4)2, has been synthesized by slow evaporation and crystallographically characterized. The title compound crystallizes at room temperature in the monoclinic centrosymmetric space group P21/n, with the following unit cell parameters: a = 7.2373(4) Å; b = 12.5600(7) Å; c = 10.1945(7) Å; β = 91.155(4)°, V = 926.50(10) Å3and Z = 2. Its crystal structure is built of manganese(II) cations coordinated by six water molecules in octahedral geometry, disordered dabcodiium cations and selenate anions, resulting in an extensive hydrogen-bonding network. Differential scanning calorimetry (DSC) measurement indicated that the precursor undergoes a reversible phase transition at about 216 and 218 K during the cooling and heating processes respectively. Below this temperature the title compound is noncentrosymmetric with space group P21 and lattice parameters a = 7.2033(8) Å; b = 12.4981(13) Å; c = 10.0888(11) Å; β = 91.281(2)°, V = 908.04(17) Å3 and Z = 2. The disorder-order transformation of the C atoms of (C6H14N2)2+ cation may drive the structural phase transition. The low temperature phase obtained by breaking symmetry presents a fully ordered structure. The noncovalent interaction (NCI) method was used not only to locate, quantify, and visualize intermolecular interactions in the high and low temperature phases but also to confirm the phase transition detected by DSC measurement. The thermal decomposition of this new compound proceeds through four stages giving rise to the manganese oxide as final product at 850 °C.

Selenium speciation profiles in biofortified sangiovese wine.

PubMed

Fontanella, Maria Chiara; D'Amato, Roberto; Regni, Luca; Proietti, Primo; Beone, Gian Maria; Businelli, Daniela

2017-09-01

Biofortification is an agronomic-based strategy, utilized by farmers, to produce selenium (Se)-enriched food products that may help reduce dietary deficiencies of Se occurring throughout susceptible regions of the world. The foliar exposure route application ensures a high efficiency of Se assimilation by the plant since it does not depend on root-to-shoot translocation. In this study we treated grapevines of Sangiovese variety in the pre-flowering period with sodium selenate (100mg Se L -1 ). Se content was measured in leaves, fruit at harvest time and in wine respectively in treated and not treated samples with ICP-MS. At harvest, a higher amount of Se in the treated leaves compared to untreated ones was found, 16.0±3.1mgkg -1 dry weight (dw) against 0.17±0.006mgkg -1 dw in the untreated ones. The treated grapes had a content of Se of 0.800±0.08mgkg -1 dw, while that untreated one 0.065±0.025mgkg -1 dw. Immediately after the malolactic fermentation, the wine obtained from treated and untreated vines had a Se content of 0.620±0.09mg Se L -1 and 0.024±0.010mg Se L -1 respectively. In our case the percentage of inorganic Se is 26% of the total Se in the untreated wine, while in Se enriched wine this percentage increase to 47.5% of the total Se. The Se(VI) was the inorganic chemical form more present in enriched wine, probably due to foliar application with selenate. Distributions of Se species suggested being careful to the choice of the enrichment solutions to promote a balanced distribution of different chemical forms, perhaps favouring the accumulation of organic forms. Copyright © 2016 Elsevier GmbH. All rights reserved.

Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: I. Column experiments under intermittent and unsaturated flow.

PubMed

Tabelin, Carlito Baltazar; Sasaki, Ryosuke; Igarashi, Toshifumi; Park, Ilhwan; Tamoto, Shuichi; Arima, Takahiko; Ito, Mayumi; Hiroyoshi, Naoki

2017-11-01

Rocks excavated in tunnel construction projects for roads and railways throughout Japan often leached out hazardous trace elements like arsenic (As) and selenium (Se) upon their exposure to the environment. In nature, the various oxyanionic species of As and Se not only coexist but also exhibit contrasting adsorption-desorption behaviors, so speciation is a crucial factor in their migration through natural geologic media. In this study, the leaching and transport of arsenite (As III ), arsenate (As V ), selenite (Se IV ) and selenate (Se VI ) in four tunnel-excavated rocks from the Cretaceous-Paleocene Yezo forearc basin were investigated using laboratory column experiments supplemented by batch leaching experiments. The single- and consecutive-batch leaching results revealed that As III , As V , Se IV and Se VI were released simultaneously, which could be attributed to the rapid dissolution of trace evaporite salts found in the rocks. Arsenic in the leachates was also predominated by As V while Se IV and Se VI concentrations were nearly equal, which are both consistent with predictions of equilibrium Eh-pH diagrams. Under intermittent and unsaturated flow, however, periods when As III and Se VI predominated in the effluents were observed. Spatial distributions of As and Se species with depth at the end of the column experiments suggest that migrations of As III , As V and Se IV were delayed, the extent of which depended on the rock. These results indicate that migration and speciation of As and Se in the rocks are controlled by preferential adsorption-desorption reactions, the effects of which were most probably magnified by changes in the pH and concentrations of coexisting ions due to intermittent and unsaturated flow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Involvement of a Broccoli COQ5 Methyltransferase in the Production of Volatile Selenium Compounds[C][OA

PubMed Central

Zhou, Xin; Yuan, Youxi; Yang, Yong; Rutzke, Michael; Thannhauser, Theodore W.; Kochian, Leon V.; Li, Li

2009-01-01

Selenium (Se) is an essential micronutrient for animals and humans but becomes toxic at high dosage. Biologically based Se volatilization, which converts Se into volatile compounds, provides an important means for cleanup of Se-polluted environments. To identify novel genes whose products are involved in Se volatilization from plants, a broccoli (Brassica oleracea var italica) cDNA encoding COQ5 methyltransferase (BoCOQ5-2) in the ubiquinone biosynthetic pathway was isolated. Its function was authenticated by complementing a yeast coq5 mutant and by detecting increased cellular ubiquinone levels in the BoCOQ5-2-transformed bacteria. BoCOQ5-2 was found to promote Se volatilization in both bacteria and transgenic Arabidopsis (Arabidopsis thaliana) plants. Bacteria expressing BoCOQ5-2 produced an over 160-fold increase in volatile Se compounds when they were exposed to selenate. Consequently, the BoCOQ5-2-transformed bacteria had dramatically enhanced tolerance to selenate and a reduced level of Se accumulation. Transgenic Arabidopsis expressing BoCOQ5-2 volatilized three times more Se than the vector-only control plants when treated with selenite and exhibited an increased tolerance to Se. In addition, the BoCOQ5-2 transgenic plants suppressed the generation of reactive oxygen species induced by selenite. BoCOQ5-2 represents, to our knowledge, the first plant enzyme that is not known to be directly involved in sulfur/Se metabolism yet was found to mediate Se volatilization. This discovery opens up new prospects regarding our understanding of the complete metabolism of Se and may lead to ways to modify Se-accumulator plants with increased efficiency for phytoremediation of Se-contaminated environments. PMID:19656903

Low-cost fabrication of ternary CuInSe{sub 2} nanocrystals by colloidal route using a novel combination of volatile and non-volatile capping agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chawla, Parul; Narain Sharma, Shailesh, E-mail: shailesh@nplindia.org; Singh, Son

2014-11-15

Wet-route synthesis of CuInSe{sub 2} (CISe) nanocrystals has been envisaged with the utilization of the unique combination of coordinating ligand and non coordinating solvent. Our work demonstrates the formation of a single-phase, nearly stoichiometric and monodispersive, stable and well-passivated colloidal ternary CISe nanocrystals (band gap (E{sub g})∼1.16 eV) using a novel combination of ligands; viz. volatile arylamine aniline and non-volatile solvent 1-octadecene. The synthesis and growth conditions have been manoeuvred using the colligative properties of the mixture and thus higher growth temperature (∼250 °C) could be attained that promoted larger grain growth. The beneficial influence of the capping agents (anilinemore » and 1-octadecene) on the properties of chalcopyrite nanocrystals has enabled us to pictorally model the structural, morphological and optoelectronic aspects of CISe nanoparticles. - Graphical abstract: Without resorting to any post-selenization process and using the colligative properties of the mixture comprising of volatile aniline and non-volatile 1-octadecene to manoeuvre the growth conditions to promote Ostwald ripening, a single phase, monodispersive and nearly stoichiometric ternary CISe nanocrystals are formed by wet-synthesis route. - Highlights: • Wet-route synthesis of CISe nanocrystals reported without post-selenization process. • Single-phase, stable and well-passivated colloidal ternary CISe nanocrystals formed. • Novel combination of capping agents: volatile aniline and non-volatile 1-octadecene. • Higher growth temperature attained using the colligative properties of the mixture. • Metallic salts presence explains exp. and theoretical boiling point difference.« less

CdS-Free p-Type Cu2ZnSnSe4/Sputtered n-Type In x Ga1- x N Thin Film Solar Cells

NASA Astrophysics Data System (ADS)

Chen, Wei-Liang; Kuo, Dong-Hau; Tuan, Thi Tran Anh

2017-03-01

Cu2ZnSnSe4 (CZTSe) films for solar cell devices were fabricated by sputtering with a Cu-Zn-Sn metal target, followed by two-step post-selenization at 500-600°C for 1 h in the presence of single or double compensation discs to supply Se vapor. After that, two kinds of n-type III-nitride bilayers were prepared by radio frequency sputtering for CdS-free CZTSe thin film solar cell devices: In0.15Ga0.85N/GaN/CZTSe and In0.15Ga0.85N/In0.3Ga0.7N/CZTSe. The p-type CZTSe and the n-type In x Ga1- x N films were characterized. The properties of CZTSe changed with the selenization temperature and the In x Ga1- x N with its indium content. With the CdS-free modeling for a solar cell structure, the In0.15Ga0.85N/In0.3Ga0.7N/CZTSe solar cell device had an improved efficiency of 4.2%, as compared with 1.1% for the conventional design with the n-type conventional ZnO/CdS bilayer. Current density of ˜48 mA/cm2, the maximum open-circuit voltage of 0.34 V, and fill factor of 27.1% are reported. The 3.8-fold increase in conversion efficiency for the CZTSe thin film solar cell devices by replacing n-type ZnO/CdS with the III-nitride bilayer proves that sputtered III-nitride films have their merits.

An intermediate in the synthesis of glucobrassicins from 3-indoleacetaldoxime by woad leaves.

PubMed

Mahadevan, S; Stowe, B B

1972-07-01

Leaves of woad (Isatis tinctoria L.) were found to incorporate efficiently tritiated indoleacetaldoxime and (35)S from (35)S-l-cystine into glucobrassicin and sulfoglucobrassicin. Time course of incorporation of (35)S from (35)S-cystine into the glucosinolates indicated that glucobrassicin was formed first and then sulfoglucobrassicin. Simultaneous administration of tritiated indoleacetaldoxime and (35)S-cystine gave doubly labeled glucobrassicin and sulfoglucobrassicin. About twice as much (35)S was present in sulfoglucobrassicin as compared to glucobrassicin per unit of (3)H incorporated, indicating that a second, probably oxidized, atom of (35)S was later introduced into sulfoglucobrassicin. However, the (35)S incorporated from cystine into both glucosinolates during the first 8 hours of metabolism was almost exclusively in the divalent sulfur moiety. The incorporation patterns of (35)S and titritated indoleacetaldoxime into the glucosinolates suggested a fast turnover of glucobrassicin in the metabolizing leaves.A new indolic, sulfur-containing neutral compound X was found to accumulate in woad leaves when administered (3)H-3-indoleacetaldoxime and cold cystine or (35)S-cystine and cold 3-indoleacetaldoxime. This accumulation was enhanced about 2- to 2.5-fold by the simultaneous administration of postassium selenate, an inhibitor of biological sulfation processes. Selenate also appeared to inhibit the conversion of glucobrassicin to 1-sulfoglucobrassicin. Partially purified compound X was efficiently converted (56-60%) to glucobrassicin and 1-sulfoglucobrassicin on readministration to woad leaves, indicating it to be a precursor of the glucosinolates. Compound X, on treatment with myrosinase, slowly yielded a less polar, indolic, sulfur containing compound Y and glucose. Compound Y decomposed with time into indoleacetonitrile suggesting that it may be indoleacetothiohydroximate. Compound X has been tentatively assigned the structure of desthioglucobrassicin, the nonsulfated form of glucobrassicin.

An Intermediate in the Synthesis of Glucobrassicins from 3-Indoleacetaldoxime by Woad Leaves 1

PubMed Central

Mahadevan, S.; Stowe, Bruce B.

1972-01-01

Leaves of woad (Isatis tinctoria L.) were found to incorporate efficiently tritiated indoleacetaldoxime and 35S from 35S-l-cystine into glucobrassicin and sulfoglucobrassicin. Time course of incorporation of 35S from 35S-cystine into the glucosinolates indicated that glucobrassicin was formed first and then sulfoglucobrassicin. Simultaneous administration of tritiated indoleacetaldoxime and 35S-cystine gave doubly labeled glucobrassicin and sulfoglucobrassicin. About twice as much 35S was present in sulfoglucobrassicin as compared to glucobrassicin per unit of 3H incorporated, indicating that a second, probably oxidized, atom of 35S was later introduced into sulfoglucobrassicin. However, the 35S incorporated from cystine into both glucosinolates during the first 8 hours of metabolism was almost exclusively in the divalent sulfur moiety. The incorporation patterns of 35S and titritated indoleacetaldoxime into the glucosinolates suggested a fast turnover of glucobrassicin in the metabolizing leaves. A new indolic, sulfur-containing neutral compound X was found to accumulate in woad leaves when administered 3H-3-indoleacetaldoxime and cold cystine or 35S-cystine and cold 3-indoleacetaldoxime. This accumulation was enhanced about 2- to 2.5-fold by the simultaneous administration of postassium selenate, an inhibitor of biological sulfation processes. Selenate also appeared to inhibit the conversion of glucobrassicin to 1-sulfoglucobrassicin. Partially purified compound X was efficiently converted (56-60%) to glucobrassicin and 1-sulfoglucobrassicin on readministration to woad leaves, indicating it to be a precursor of the glucosinolates. Compound X, on treatment with myrosinase, slowly yielded a less polar, indolic, sulfur containing compound Y and glucose. Compound Y decomposed with time into indoleacetonitrile suggesting that it may be indoleacetothiohydroximate. Compound X has been tentatively assigned the structure of desthioglucobrassicin, the nonsulfated form of glucobrassicin. PMID:16658130

Adsorption-desorption reactions of selenium (VI) in tropical cultivated and uncultivated soils under Cerrado biome.

PubMed

Lessa, J H L; Araujo, A M; Silva, G N T; Guilherme, L R G; Lopes, G

2016-12-01

Soil management may affect selenium (Se) adsorption capacity. This study investigated adsorption and desorption of Se (VI) in selected Brazilian soils from the Cerrado biome, an area of ever increasing importance for agriculture expansion in Brazil. Soil samples were collected from cultivated and uncultivated soils, comprising clayed and sandy soils. Following chemical and mineralogical characterization, soil samples were subjected to Se adsorption and desorption tests. Adsorption was evaluated after a 72-h reaction with increasing concentrations of Se (0-2000 μg L -1 ) added as Na 2 SeO 4 in a NaCl electrolyte solution (pH 5.5; ionic strength 15 mmol L -1 ). Desorption, as well as distribution coefficients (K d ) for selenate were also assessed. Soil management affected Se adsorption capacity, i.e., Se adsorbed amounts were higher for uncultivated soils, when compared to cultivated ones. Such results were also supported by data of K d and maximum adsorption capacity of Se. This fact was attributed mainly to the presence of greater amounts of competing anions, especially phosphate, in cultivated soils, due to fertilizer application. Phosphate may compete with selenate for adsorption sites, decreasing Se retention. For the same group of soils (cultivated and uncultivated), Se adsorption was greater in the clayed soils compared to sandy ones. Our results support the idea that adding Se (VI) to the soil is a good strategy to increase Se levels in food crops (agronomic biofortification), especially when crops are grown in soils that have been cultivated over the time due to their low Se adsorption capacity (high Se availability). Copyright © 2016 Elsevier Ltd. All rights reserved.

In vivo bioavailability of selenium in enriched Pleurotus ostreatus mushrooms.

PubMed

da Silva, Marliane C S; Naozuka, Juliana; Oliveira, Pedro V; Vanetti, Maria C D; Bazzolli, Denise M S; Costa, Neuza M B; Kasuya, Maria C M

2010-02-01

The in vivo bioavailability of Se was investigated in enriched Pleurotus ostreatus mushrooms. A bioavailability study was performed using 64 Wistar male rats separated in 8 groups and fed with different diets: without Se, with mushrooms without Se, with enriched mushrooms containing 0.15, 0.30 or 0.45 mg kg(-1) Se and a normal diet containing 0.15 mg kg(-1) of Se using sodium selenate. The experiment was performed in two periods: depletion (14 days) and repletion (21 days), according to the Association of Official Analytical Chemists. After five weeks, the rats were sacrificed under carbon dioxide, and blood was drawn by heart puncture. Blood plasma was separated by centrifugation. The total Se concentration in the plasma of rats fed with enriched mushrooms was higher than in rats fed with a normal diet containing sodium selenate. The plasma protein profiles were obtained using size exclusion chromatography (SEC) and UV detectors. Aliquots of effluents (0.5 mL per minute) were collected throughout in the end of the chromatographic column. However, Se was determined by graphite furnace atomic absorption spectrometry (GF AAS) only in the aliquots where proteins were detected by SEC-UV. The plasma protein profile of rats fed with different diets was similar. The highest Se concentration was observed in a peptide presenting 8 kDa. Furthermore, the higher Se concentration in this peptide was obtained for rats fed with a diet using enriched mushrooms (7 μg L(-1) Se) compared to other diets (2-5 μg L(-1) Se). These results showed that Se-enriched mushrooms can be considered as an alternative Se food source for humans, due to their high bioavailability.

Subacute toxicity of nano-selenium compared to other selenium species in mice.

PubMed

Benko, Ilona; Nagy, Gabor; Tanczos, Bence; Ungvari, Eva; Sztrik, Attila; Eszenyi, Peter; Prokisch, Jozsef; Banfalvi, Gaspar

2012-12-01

Sixteen groups of mice were fed diets containing different selenium species to compare their toxicity. Inorganic sodium selenate and sodium hydroselenite, elementary nanoSe, organic Sel-Plex, and Lacto-MicroSelenium were administered for 14 d at concentrations of 0.5, 5, and 50 ppm Se, equivalent to 0.5, 5, and 50 mg Se/kg food, corresponding to an estimated 4, 40, and 400 µg/kg body weight/d Se uptake, respectively. At the end of the treatment, body, liver, spleen, kidney, heart, and brain weights were measured, mice were subjected to necropsy, and histological examinations were performed on the liver. At lower Se doses (0.5 and 5 ppm) a moderate reduction was observed in the number of bone marrow and white blood cells and in granulocyte-macrophage colony-forming units (GM-CFUs) relative to the untreated control group of mice. A comparison of lowest toxic doses of sodium selenite in mice (0.5 ppm) and mallard (10 ppm) indicates that birds are more resistant to Se than rodents. In mice, a small but measurable weight loss was observed after 5 ppm selenate and LactoMicroSe treatment. The most significant changes took place after 50-ppm administration in body and spleen weight, hematology, and liver histology. Toxicity was more pronounced when inorganic Se was applied than after subacute application of Sel-Plex, nanoSe, or LactoMicroSe. To summarize the effects, the authors' 14-d murine subacute toxicity study showed that the toxicity of Se species decreased in the following order: selenate > selenite > nanoSe > Sel-Plex > LactoMicroSe. Copyright © 2012 SETAC.

Towards a selective adsorbent for arsenate and selenite in the presence of phosphate: Assessment of adsorption efficiency, mechanism, and binary separation factors of the chitosan-copper complex.

PubMed

Yamani, Jamila S; Lounsbury, Amanda W; Zimmerman, Julie B

2016-01-01

The potential for a chitosan-copper polymer complex to select for the target contaminants in the presence of their respective competitive ions was evaluated by synthesizing chitosan-copper beads (CCB) for the treatment of (arsenate:phosphate), (selenite:phosphate), and (selenate:sulfate). Based on work by Rhazi et al., copper (II) binds to the amine moiety on the chitosan backbone as a monodentate complex (Type I) and as a bidentate complex crosslinking two polymer chains (Type II), depending on pH and copper loading. In general, the Type I complex exists alone; however, beyond threshold conditions of pH 5.5 during synthesis and a copper loading of 0.25 mol Cu(II)/mol chitosan monomer, the Type I and Type II complexes coexist. Subsequent chelation of this chitosan-copper ligand to oxyanions results in enhanced and selective adsorption of the target contaminants in complex matrices with high background ion concentrations. With differing affinities for arsenate, selenite, and phosphate, the Type I complex favors phosphate chelation while the Type II complex favors arsenate chelation due to electrostatic considerations and selenite chelation due to steric effects. No trend was exhibited for the selenate:sulfate system possibly due to the high Ksp of the corresponding copper salts. Binary separation factors, α12, were calculated for the arsenate-phosphate and selenite-phosphate systems, supporting the mechanistic hypothesis. While, further research is needed to develop a synthesis method for the independent formation of the Type II complexes to select for target contaminants in complex matrices, this work can provide initial steps in the development of a selective adsorbent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bioaccumulation of organic and inorganic selenium in a laboratory food chain

USGS Publications Warehouse

Besser, John M.; Canfield, Timothy J.; La Point, Thomas W.

1993-01-01

Aquatic organisms accumulated selenium (Se) from inorganic and organic Se species via aqueous and food-chain exposure routes. We measured aqueous and food-chain Se bioaccumulation from selenate, selenite, and seleno-L-methionine in a laboratory food chain of algae (Chlamydomonas reinhardtii), daphnids (Daphnia magna), and fish (bluegill, Lepomis macrochirus). Selenium concentrations were monitored radiometrically with 75Se-labeled compounds. All three organisms concentrated Se more strongly from aqueous selenomethionine than from either inorganic Se species. Bioconcentration factors (BCFs) estimated from 1 μg Se/L Se-methionine exposures were approximately 16,000 for algae, 200,000 for daphnids, and 5,000 for bluegills. Algae and daphnids concentrated Se more strongly from selenite (BCFs = 220–3,600) than selenate (BCFs = 65–500) whereas bluegills concenrated Se about equally from both inorganic species (estimated BCFs = 13 to 106). Bioaccumulation of foodborne Se by daphnids and bluegills was similar in food chains dosed with different Se species. Daphnids and bluegills did not accumulate Se concentrations greater than those in their diet, except at very low dietary Se concentrations. Food-chain concentration factors (CFs) for daphnids decreased from near 1.0 to 0.5 with increases in algal Se concentrations, whereas CFs estimated from bluegill exposures averaged 0.5 over a range of foodborne Se concentrations. In exposures based on selenite, bluegills accumulated greater Se concentrations from food than from water. Aqueous and food-chain Se uptakes were approximately additive, and depuration rates were similar in aqueous, food-chain, and combined exposures. Our results suggest that bluegills in Secontaminated habitats accumulate inorganic Se species primarily via food-chain uptake, although organoselenium compounds such as Se-methionine may contribute significantly to Se bioaccumulation by bluegills via both aqueous and food-chain uptake.

Isolation and characterization of Sulfurospirillum carboxydovorans sp. nov., a new microaerophilic carbon monoxide oxidizing epsilon Proteobacterium.

PubMed

Jensen, Anders; Finster, Kai

2005-05-01

A new microaerophilic, Gram-negative, motile, 2-3 microm long and 0.3 microm wide, vibrioid to spirillum-shaped, CO oxidizing bacterium, designated strain MV, isolated from marine sediment (The North Sea) is described. Strain MV was able to couple the oxidation of CO to the reduction of elemental sulphur, DMSO and thiosulphate. Growth occurred with up to 100% (v/v) CO in the headspace. Acetate was needed as carbon source. No growth on CO was observed with nitrate and selenate as electron acceptor. Sulphite, elemental sulphur, DMSO, thiosulphate, nitrate, nitrite, perchloroethylene, arsenate and selenate were used as electron acceptors with pyruvate as energy and carbon source. Microaerophilic growth was observed. In non-agitated cultures growth occurred at atmospheric oxygen concentrations in the headspace. Hydrogen (with acetate as carbon source), formate (with acetate as carbon source), pyruvate, lactate, succinate, fumarate, malate alpha-ketoglutaric acid, aspartate and yeast extract (1% (w/v)) supported growth with nitrate as electron acceptor. Fumarate and malate were fermented. Vitamins were not required for growth. The strain was cytochrome C oxidase and catalase positive. The DNA mol G+C content was 30.5%. 16S rRNA gene sequence comparison showed that strain MV grouped within the genus Sulfurospirillum with Sulfurospirillum arcachonense (sequence similarity 98.3%) as closest relative. The relative DNA-DNA relatedness between strain MV and S. arcachonense was 33.1%. Based on a detailed phenotypic and phylogenetic analysis, inclusion of strain MV in the genus Sulfurospirillum as a well separated new species is proposed. As species name we propose Sulfurospirillum carboxydovorans. The type strain is strain MV (ATCC BAA-937 = DSM 16295, GenBank accession number: AY740528).

Data Visualization of Lunar Orbiter KAGUYA (SELENE) using web-based GIS

NASA Astrophysics Data System (ADS)

Okumura, H.; Sobue, S.; Yamamoto, A.; Fujita, T.

2008-12-01

The Japanese Lunar Orbiter KAGUYA (SELENE) was launched on Sep.14 2007, and started nominal observation from Dec. 21 2007. KAGUYA has 15 ongoing observation missions and is obtaining various physical quantity data of the moon such as elemental abundance, mineralogical composition, geological feature, magnetic field and gravity field. We are working on the visualization of these data and the application of them to web-based GIS. Our purpose of data visualization is the promotion of science and education and public outreach (EPO). As for scientific usage and public outreach, we already constructed KAGUYA Web Map Server (WMS) at JAXA Sagamihara Campus and began to test it among internal KAGUYA project. KAGUYA science team plans the integrated science using the data of multiple instruments with the aim of obtaining the new findings of the origin and the evolution of the moon. In the study of the integrated science, scientists have to access, compare and analyze various types of data with different resolution. Web-based GIS will allow users to map, overlay and share the data and information easily. So it will be the best way to progress such a study and we are developing the KAGUYA WMS as a platform of the KAGUYA integrated science. For the purpose of EPO, we are customizing NASA World Wind (NWW) JAVA for KAGUYA supported by NWW project. Users will be able to search and view many images and movies of KAGUYA on NWW JAVA in the easy and attractive way. In addition, we are considering applying KAGUYA images to Google Moon with KML format and adding KAGUYA movies to Google/YouTube.

Recrystallization method to selenization of thin-film Cu(In,Ga)Se.sub.2 for semiconductor device applications

DOEpatents

Albin, David S.; Carapella, Jeffrey J.; Tuttle, John R.; Contreras, Miguel A.; Gabor, Andrew M.; Noufi, Rommel; Tennant, Andrew L.

1995-07-25

A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550.degree. C.) at which Cu(In,Ga)Se.sub.2 is solid and Cu.sub.x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu.sub.x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu.sub.x (In,Ga).sub.y Se.sub.z. The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450.degree. C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100.degree. C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.

Characterization of the selenite uptake mechanism in the coccolithophore Emiliania huxleyi (Haptophyta).

PubMed

Araie, Hiroya; Sakamoto, Kou; Suzuki, Iwane; Shiraiwa, Yoshihiro

2011-07-01

The marine coccolithophore Emiliania huxleyi (Haptophyta) requires selenium as an essential element for growth, and the active species absorbed is selenite, not selenate. This study characterized the selenite uptake mechanism using ⁷⁵Se as a tracer. Kinetic analysis of selenite uptake showed the involvement of both active and passive transport processes. The active transport was suppressed by 0.5 mM vanadate, a membrane-permeable inhibitor of H⁺-ATPase, at pH 8.3. When the pH was lowered from 8.3 to 5.3, the selenite uptake activity greatly increased, even in the presence of vanadate, suggesting that the H⁺ concentration gradient may be a motive force for selenite transport. [⁷⁵Se]Selenite uptake at selenite-limiting concentrations was hardly affected by selenate, sulfate and sulfite, even at 100 μM. In contrast, 3 μM orthophosphate increased the K(m) 5-fold. These data showed that HSeO₃⁻, a dominant selenite species at acidic pH, is the active species for transport through the plasma membrane and transport is driven by ΔpH energized by H⁺-ATPase. Kinetic analysis showed that the selenite uptake activity was competitively inhibited by orthophosphate. Furthermore, the active selenite transport mechanism was shown to be induced de novo under Se-deficient conditions and induction was suppressed by the addition of either sufficient selenite or cycloheximide, an inhibitor of de novo protein synthesis. These results indicate that E. huxleyi cells developed an active selenite uptake mechanism to overcome the disadvantages of Se limitation in ecosystems, maintaining selenium metabolism and selenoproteins for high viability.

Suspended Ga2Se3 film and epitaxial Bi2Se3(221) on GaSb(001) by molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Li, Bin; Xia, Yipu; Ho, Wingkin; Xie, Maohai

2017-02-01

High-index Bi2Se3(221) has been successfully grown on partially suspended Ga2Se3(001). The Ga2Se3 layer was formed by selenation of GaSb(001) surface, which revealed a suspended structure supported only by some GaSb nano-pillars. Such a growth behavior may be beneficial for achieving heterostructures with large lattice misfits and suppressing the coupling between the substrate and deposit. Bi2Se3, a typical topological insulator, has been grown on Ga2Se3 along the high-index [221] direction despite of the large lattice mismatch.

The solar wind - Moon interaction discovered by MAP-PACE on KAGUYA

NASA Astrophysics Data System (ADS)

Saito, Y.; Yokota, S.; Tanaka, T.; Asamura, K.; Nishino, M. N.; Yamamoto, T.; Tsunakawa, H.; Shibuya, H.; Shimizu, H.; Takahashi, F.

2009-12-01

Magnetic field And Plasma experiment - Plasma energy Angle and Composition Experiment (MAP-PACE) on KAGUYA (SELENE) completed its ˜1.5-year observation of the low energy charged particles around the Moon. SELENE was successfully launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. SELENE was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to ˜50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of ˜10km after April 2009. The newly observed data showed characteristic ion distributions around the Moon. Besides the solar wind, one of the MAP-PACE sensors MAP-PACE-IMA (Ion Mass Analyzer) discovered four clearly distinguishable ion distributions on the dayside of the Moon: 1) Solar wind ions backscattered at the lunar surface, 2) Solar wind ions reflected by magnetic anomalies on the lunar surface, 3) Ions that are originating from the reflected / backscattered solar wind ions and are pick-up accelerated by the solar wind convection electric field, and 4) Ions originating from the lunar surface / lunar atmosphere. One of the most important discoveries of the ion mass spectrometer (MAP-PACE-IMA) is the first in-situ measurements of the alkali ions originating from the Moon surface / atmosphere. The ions generated on the lunar surface by solar wind sputtering, solar photon stimulated desorption, or micro-meteorite vaporization are accelerated by the solar wind convection electric field and detected by IMA. The mass profiles of these ions show ions including He+, C+, O+, Na+, and K+/Ar+. The heavy ions were also observed when the Moon was in the Earth’s magnetotail where no solar wind ions impinged on the lunar surface. This discovery strongly restricts the possible generation mechanisms of the ionized alkali atmosphere around the Moon. When KAGUYA flew over South Pole Aitken region, where strong magnetic anomalies exist, solar wind ions reflected by magnetic anomalies were observed. These reflected ions had nearly the same energy as the incident solar wind ions, and their flux was more than 10% of the incident solar wind ions. At 100km altitude, when the reflected ions were observed, the simultaneously measured electrons were often heated and the incident solar wind ions were sometimes slightly decelerated. At ~50km altitude, when the reflected ions were observed, proton scattering at the lunar surface clearly disappeared. At ~10km altitude, the interaction between the solar wind ions and the lunar magnetic anomalies was remarkable with clear deceleration of the incident solar wind ions and heating of the reflected ions as well as significant heating of the electrons. These newly discovered plasma signatures around the Moon are the evidences of the smallest magnetosphere ever observed.

Selective Se-for-S substitution in Cs-bearing uranyl compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru; Tyumentseva, Olga S.; Krivovichev, Sergey V.

Phase formation in the mixed sulfate-selenate aqueous system of uranyl nitrate and cesium nitrate has been investigated. Two types of crystalline compounds have been obtained and characterized using a number of experimental (single crystal XRD, FTIR, SEM) and theoretical (information-based complexity calculations, topological analysis) techniques. No miscibility gaps have been observed for Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}] (T= S, Se), which crystallizes in tetragonal system, P-42{sub 1}m, a =9.616(1)–9.856(2), c =8.105(1)–8.159(1) Å, V =749.6(2)–792.5(3) Å{sup 3}. Nine phases with variable amount of S and Se have been structurally characterized. The structures of the Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}]more » (T= S, Se) compounds are based upon the [(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}]{sup 2-} layers of corner-sharing uranyl pentagonal bipyramids and TO{sub 4} tetrahedra. The layers contain two types of tetrahedral sites: T1 (3-connected, i.e. having three O atoms shared by adjacent uranyl polyhedra) and T2 (4-connected). The Se-for-S substitution in tetrahedral sites is highly selective with smaller S{sup 6+} cation showing a strong preference for the more tightly bonded T2 site. Crystallization in the pure Se system starts with the formation of Cs{sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) crystals, its subsequent dissolution and formation of Cs{sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}]. The information-based structural complexity calculations for these two phases support the rule that more topologically complex structures form at the latest stages of crystallization. - Graphical abstract: Nine phases representing the Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}] (T= S, Se) solid solution series with variable amount of S and Se have been prepared by isothermal evaporation from aqueous solutions and characterized using a number of experimental and theoretical techniques. No immiscibility is observed between the pure sulfate and selenate compounds. The Se-for-S substitution in tetrahedral sites is highly selective with smaller S{sup 6+} cation showing a strong preference for the more tightly bonded 4-connected site. - Highlights: • Single crystals of novel mixed sulfate-selenate uranyl oxysalts were prepared by evaporation method. • Topological analysis and information-based complexity calculations were used for structure description. • The selective Se-for-S substitution was observed. • Evolution of phase formation in the aqueous Cs{sup +}–UO{sub 2}{sup 2+}–SO{sub 4}{sup 2–}–SeO{sub 4}{sup 2–} system was analyzed.« less

Selenium Speciation and Management in Wet FGD Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Searcy, K; Richardson, M; Blythe, G

2012-02-29

This report discusses results from bench- and pilot-scale simulation tests conducted to determine the factors that impact selenium speciation and phase partitioning in wet FGD systems. The selenium chemistry in wet FGD systems is highly complex and not completely understood, thus extrapolation and scale-up of these results may be uncertain. Control of operating parameters and application of scrubber additives have successfully demonstrated the avoidance or decrease of selenite oxidation at the bench and pilot scale. Ongoing efforts to improve sample handling methods for selenium speciation measurements are also discussed. Bench-scale scrubber tests explored the impacts of oxidation air rate, tracemore » metals, scrubber additives, and natural limestone on selenium speciation in synthetic and field-generated full-scale FGD liquors. The presence and concentration of redox-active chemical species as well as the oxidation air rate contribute to the oxidation-reduction potential (ORP) conditions in FGD scrubbers. Selenite oxidation to the undesirable selenate form increases with increasing ORP conditions, and decreases with decreasing ORP conditions. Solid-phase manganese [Mn(IV)] appeared to be the significant metal impacting the oxidation of selenite to selenate. Scrubber additives were tested for their ability to inhibit selenite oxidation. Although dibasic acid and other scrubber additives showed promise in early clear liquor (sodium based and without calcium solids) bench-scale tests, these additives did not show strong inhibition of selenite oxidation in tests with higher manganese concentrations and with slurries from full-scale wet FGD systems. In bench-tests with field liquors, addition of ferric chloride at a 250:1 iron-to-selenium mass ratio sorbed all incoming selenite to the solid phase, although addition of ferric salts had no impact on native selenate that already existed in the field slurry liquor sample. As ORP increases, selenite may oxidize to selenate more rapidly than it sorbs to ferric solids. Though it was not possible to demonstrate a decrease in selenium concentrations to levels below the project'ale testing were evident at the pilot scale. Specifically, reducing oxidation air rate and ORP tends to either retain selenium as selenite in the liquor or shift selenium phase partitioning to the solid phase. Oxidation air flow rate control may be one option for managing selenium behavior in FGD scrubbers. Units that cycle load widely may find it more difficult to impact ORP conditions with oxidation air flow rate control alone. Because decreasing oxidation air rates to the reaction tank showed that all new selenium reported to the solids, the addition of ferric chloride to the pilot scrubber could not show further improvements in selenium behavior. Ferric chloride addition did shift mercury to the slurry solids, specifically to the fine particles. Several competing pathways may govern the reporting of selenium to the slurry solids: co-precipitation with gypsum into the bulk solids and sorption or co-precipitation with iron into the fine particles. Simultaneous measurement of selenium and mercury behavior suggests a holistic management strategy is best to optimize the fate of both of these elements in FGD waters. Work conducted under this project evaluated sample handling and analytical methods for selenium speciation in FGD waters. Three analytical techniques and several preservation methods were employed. Measurements of selenium speciation over time indicated that for accurate selenium speciation, it is best to conduct measurements on unpreserved, filtered samples as soon after sampling as possible. The capital and operating costs for two selenium management strategies were considered: ferric chloride addition and oxidation air flow rate control. For ferric chloride addition, as might be expected the reagent makeup costs dominate the overall costs, and range from 0.22 to 0.29 mills/kWh. For oxidation air flow rate control, a cursory comparison of capital costs and turndown capabilities for multi-stage and single-stage centrifugal blowers and several flow control methods was completed. For greenfield systems, changing the selection of blower type and flow control method may have payback periods of 4 to 5 years or more if based on energy savings alone. However, the benefits to managing redox chemistry in the scrubber could far outweigh the savings in electricity costs under some circumstances.« less

Expulsion of selenium/protein nanoparticles through vesicle-like structures by Saccharomyces cerevisiae under microaerophilic environment.

PubMed

Zhang, Liang; Li, Daping; Gao, Ping

2012-12-01

Nano-selenium/protein is a kind of lower toxic supplement to human. Many microorganisms can reduce selenite/selenate to intracellular or extracellular selenium nanoparticles. This study examined the influence of dissolved oxygen on the expulsion of extracellular selenium/protein produced in Saccharomyces cerevisiae. More of the added selenite was reduced to extracellular selenium nanoparticles by yeast cells only under oxygen-limited condition than under aerobic or anaerobic condition. For the first time, we evidenced that selenium/protein nanoparticles synthesized in vivo were transported out of the cells by vesicle-like structures under microaerophilic environment. The characterizations of the extracellular spherical selenium/protein nanoparticles were also examined by SEM, TEM, EDX and FTIR.

Dimethylselenide and Dimethyltelluride Formation by a Strain of Penicillium

PubMed Central

Fleming, R. W.; Alexander, M.

1972-01-01

A strain of Penicillium which produced dimethylselenide from inorganic selenium compounds was isolated from raw sewage. Sulfate and methionine enhanced growth of the fungus and its production of dimethylselenide in media containing selenite. In solutions containing selenate, methionine inhibited dimethylselenide formation while stimulating proliferation of the fungus. Dimethylselenide was also generated from inorganic selenide. Alkylation did not appear to be a significant mechanism of selenium detoxication by this organism. Dimethyltelluride was also produced by the organism from several tellurium compounds, but this product was synthesized only in the presence of both tellurium and selenium. The yields of dimethylselenide and dimethyltelluride varied with the relative concentrations of selenium and tellurium in the medium. PMID:5079352

Investigation of Sb-Containing Precursors for Cu(In, Ga)Se2 Thin Films Through Design of Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansfield, Lorelle M.; To, Bobby; Reedy, Robert C.

2016-11-21

The Design of Experiments (DoE) module in JMP statistical software was used to determine the best parameters for Sb-containing CIGS precursors with a fixed selenization step. Solar cells were fabricated and measured for all completed films. The most important factor influencing the current-voltage device parameters was identified as the temperature and antimony flux interaction. The DoE prediction profiler and predictive contour plots provided guidance to further improve the device parameters. In one follow-up run, we increased device efficiency from 14.9% to 15.5% Additional gains in efficiency to 16.9% were realized by introducing an intentional Ga gradient and an antireflective coating.

Anions coordinating anions: analysis of the interaction between anionic Keplerate nanocapsules and their anionic ligands.

PubMed

Melgar, Dolores; Bandeira, Nuno A G; Bonet Avalos, Josep; Bo, Carles

2017-02-15

Keplerates are a family of anionic metal oxide spherical capsules containing up to 132 metal atoms and some hundreds of oxygen atoms. These capsules holding a high negative charge of -12 coordinate both mono-anionic and di-anionic ligands thus increasing their charge up to -42, even up to -72, which is compensated by the corresponding counter-cations in the X-ray structures. We present an analysis of the relative importance of several energy terms of the coordinate bond between the capsule and ligands like carbonate, sulphate, sulphite, phosphinate, selenate, and a variety of carboxylates, of which the overriding component is contributed by solvation/de-solvation effects.

Selenization of Cu2ZnSnS4 Enhanced the Performance of Dye-Sensitized Solar Cells: Improved Zinc-Site Catalytic Activity for I3.

PubMed

Wang, Xiuwen; Xie, Ying; Bateer, Buhe; Pan, Kai; Jiao, Yanqing; Xiong, Ni; Wang, Song; Fu, Honggang

2017-11-01

Cu 2 ZnSnS 4 (CZTS) and Cu 2 ZnSn(S,Se) 4 (CZTSSe) as promising photovoltaic materials have drawn much attention because they are environmentally benign and earth-abundant elements. In this work, the monodispersed, low-cost Cu 2 ZnSnS 4 nanocrystals with small size have been controllably synthesized via a wet chemical routine. And CZTSSe could be easily prepared after selenization of CZTS. When they are employed as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), the power conversion efficiency (PCE) has been improved from 3.54% to 7.13% as CZTS is converted to CZTSSe, which is also compared to that of Pt (7.62%). The exact reason for the enhanced catalytic activity of I 3 - is discussed with the work function and density functional theory (DFT) when CZTSSe converted from CZTS. The results of a Kelvin probe suggest that the work function of CZTSSe (5.61 eV) is closer to that of Pt (5.65 eV) and higher than that of CZTS, which matched the redox shuttle potential better. According to the theory calculation, all the atomic and bond populations changed significantly when Se replaced partly the S on the CZTS system, especially in the Zn site. During the catalytic process as CEs, the adsorption energy obviously increased compared to those at other sites when I 3 - adsorbed on the Zn site in CZTSSe. So, Zn plays an important role for the reduction of I 3 - after CZTS is converted to CZTSSe. Based on above analysis, the reason for enhanced performance of DSSCs when CZTS converted to CZTSSe is mainly due to the enhancement of Zn-site activity. This work is beneficial for understanding the catalytic reaction mechanism of CZTS(Se) as CEs of DSSCs.

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods1[OA

PubMed Central

Bañuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.; Marcus, Matthew A.; Yang, Soo In; Pickering, Ingrid J.; Pilon-Smits, Elizabeth A.H.; Freeman, John L.

2011-01-01

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping (μXRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). μXRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tips contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a “free” nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. μXRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers. PMID:21059825

Surface Modification of Cu(In,Ga)Se2 Grains

NASA Astrophysics Data System (ADS)

Alruqobah, Essam H.

Nearly all of the world’s energy demand today is being met by the use of non-renewable energy sources. With the worldwide energy demand projected to increase in the coming years, it is vital to find alternative and renewable energy sources. Among the available renewable energy sources, solar energy is the most promising in meeting the worldwide energy demand. Recently, thin film solar cells have garnered attention due to their thinner architecture and relatively high optical absorption coefficients, as opposed to the conventional crytslline silicon solar cells. One of the most promising thin-film solar cell absorber materials is Cu(In,Ga)Se2 (CIGSe), achieving power conversion efficiencies approaching those of crystalline Si. The highest efficiency CIGSe devices were made via costly vacuum-based co-evaporation process. CIGSe devices made from solution-processed methods have also garnered attention due to their lower costs, and their efficiencies have increased considerably in recent years. In this thesis, CIGSe absorber layers are fabricated via the solution-processed from nanoparticle-based sulfide CIGS. The most important step in fabrication of a CIGSe solar cell absorber layer is the selenization step, which is the thermal sintering of a CIGSe precursor layer in the presence of selenium vapor to achieve large, dense selenide grains that are required for adequate PV performance. It is determined that maintaining adequate selenium vapor pressure on the substrate during the selenization and subsequent cooldown is crucial in producing high efficiency solar cell devices. Furthermore, exposing the CIGSe grains to a Se-deficient atmosphere causes Se to evaporate from the grains, and subsequently modifying the CIGSe grain surface. The modified grain surface adversely impacts the PV performance of the final solar cell device by forming defects due to the decrease in selenium concentration. These defects are manifested in increased current shunting, and decrease the overall efficiency of the device.

Selenium speciation and partitioning within Burkholderia cepacia biofilms formed on α-Al 2O 3 surfaces

NASA Astrophysics Data System (ADS)

Templeton, Alexis S.; Trainor, Thomas P.; Spormann, Alfred M.; Brown, Gordon E.

2003-10-01

The distribution and speciation of Se within aerobic Burkholderia cepacia biofilms formed on α-Al 2O 3 (1-102) surfaces have been examined using grazing-angle X-ray spectroscopic techniques. We present quantitative information on the partitioning of 10 -6 M to 10 -3 M selenate and selenite between the biofilms and underlying alumina surfaces derived from long-period X-ray standing wave (XSW) data. Changes in the Se partitioning behavior over time are correlated with microbially induced reduction of Se(VI) and Se(IV) to Se(0), as observed from X-ray absorption near edge structure (XANES) spectroscopy. Selenite preferentially binds to the alumina surfaces, particularly at low [Se], and is increasingly partitioned into the biofilms at higher [Se]. When B. cepacia is metabolically active, B. cepacia rapidly reduces a fraction of the SeO 32- to red elemental Se(0). In contrast, selenate is preferentially partitioned into the B. cepacia biofilms at all [Se] tested due to a lower affinity for binding to the alumina surface. Rapid reduction of SeO 42- by B. cepacia to Se(IV) and Se(0) subsequently results in a vertical segregation of Se species at the B. cepacia/α-Al 2O 3 interface. Elemental Se(0) accumulates within the biofilm with Se(VI), whereas Se(IV) intermediates preferentially sorb to the alumina surface. B. cepacia/α-Al 2O 3 samples incubated with SeO 42- and SeO 32- when the bacteria were metabolically active result in a significant reduction in the mobility of Se vs. X-ray treated biofilms. Remobilization experiments show that a large fraction of the insoluble Se(0) produced within the biofilm is retained during exchange with Se-free solutions. In addition, Se(IV) intermediates generated during Se(VI) reduction are preferentially bound to the alumina surface and do not fully desorb. In contrast, Se(VI) is rapidly and extensively remobilized.

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping ({micro}XRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). {micro}XRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tipsmore » contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a 'free' nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. {micro}XRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers.« less

Selenium Uptake and Volatilization by Marine Algae

NASA Astrophysics Data System (ADS)

Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.

2015-04-01

Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se, especially in low phosphate regimes such as oligotrophic waters and late stage phytoplankton blooms.

Nanocrystal synthesis and thin film formation for earth abundant photovoltaics

NASA Astrophysics Data System (ADS)

Carter, Nathaniel J.

Providing access to on-demand energy at the global scale is a grand challenge of our time. The fabrication of solar cells from nanocrystal inks comprising earth abundant elements represents a scalable and sustainable photovoltaic technology with the potential to meet the global demand for electricity. Solar cells with Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers are of particular interest due to the high absorption coefficient of CZTSSe, its band gap in the ideal range for efficient photovoltaic power conversion, and the relative abundance of its constituent elements in the earth's crust. Despite the promise of this material system, CZTSSe solar cell efficiencies reported throughout literature have failed to exceed 12.6%, principally due to the low open-circuit voltage (VOC) achieved in these devices compared to the absorber band gap. The work presented herein primarily aims to address the low VOC problem. First, the fundamental cause for such low VOC's is investigated. Interparticle compositional inhomogeneities identified in the synthesized CZTS nanocrystals and their effect on the absorber layer formation and device performance are characterized. Real-time energy-dispersive x-ray diffraction (EDXRD) elucidates the role of these inhomogeneities in the mechanism by which a film of CZTS nanocrystals converts into a dense absorber layer comprising micron-sized CZTSSe grains upon annealing in a selenium atmosphere (selenization). Additionally, a direct correlation between the nanocrystal inhomogeneities and the VOC in completed devices is observed. Detailed characterization of CZTSSe solar cells identifies electrical potential fluctuations in the CZTSSe absorber - due to spatial composition variations not unlike those observed in the nanocrystals - as a primary V OC inhibitor. Additional causes for low VOC's in CZTSSe solar cells proposed in the literature involve recombination at the interface between the CZTSSe absorber and: (1) the n-type, CdS buffer layer, or (2) the Mo back contact, and work is presented to address these issues. A chemical-mechanical polishing procedure is developed to afford modification of the CZTSSe absorber surface, and in turn the CZTSSe/CdS interface. However, such treatment results in a failure of the resultant solar cells to produce any photogenerated current without annealing/selenizing the absorber again prior to the deposition of CdS. For nanocrystal-based CZTSSe solar cells, the possibility of V OC limitations due to back surface recombination may be related to the formation of the C- and Se-rich layer of fine grains between the CZTSSe layer and the Mo contact, which is largely attributed to the long-chain organic solvent and ligand typically utilized in formulating the nanocrystal ink. CZTS nanocrystals are synthesized using a lighter but chemically similar organic solvent, and while films selenized from these particles appear to contain qualitatively less carbon, devices with these absorbers fail to produce noteworthy efficiencies. Finally, Cu2ZnSn(S,Se)4 (CMTSSe) is investigated as a proof-of-concept PV material due to its structural similarity to CZTSSe and the magnetic properties of Mn, which may prove advantageous in spintronic photovoltaic hybrid devices. While initial results demonstrate diode behavior and photoresponse from a CMTSSe/CdS junction, further processing optimization is necessary to realize meaningful device efficiencies.

A Simulation Model of the Common Strategic Rotary Launcher for Availability.

DTIC Science & Technology

1984-11-01

8217.iii . QI) I-;IC! SY ’.*,O[Q I, OF MUNI10HIN-G 0hf-,ANiZATIO𔃾 _) 110( C rri C’ir If apr-Ue __fAF IT/L,.S 11 It, Sluie arid / - ,,dc Th ,70)FL7, fc~fy...importaUnt dimce 0-cmt clodhis CREATE oRESAT. TONISL . M.VM. Nabe ube o ets ntte t h crrn tm SELEN ON. mAK(N. OLILS;) mltied from t il mouererai ucto...032 23.195 .!00 .25075 .L0734 c., ’ i3F 1.529 .307 4.972 .045 .53239 .1337) SY L V.L 377 .193 3.313 .)52 .6579 .23 15 𔃺lSfAqf 74.919 5.974 157.303

Thermodynamic Properties of M2EO4, M2Mo x O3 x + 1 and Double Chromates (M = Li, Na, K, Rb, Cs; E = Cr, Mo, W)

NASA Astrophysics Data System (ADS)

Suponitskiy, Yu. L.; Zolotova, E. S.; Dyunin, A. G.; Liashenko, S. E.

2018-03-01

The phase transition temperatures of chromates and molybdates of certain alkali metals, and the melting temperature and enthalpy of polymorphic transformations for tungstates, are determined by means of thermal analysis. Enthalpies of dissolution of rubidium and cesium chromates in water and enthalpies of dissolution of alkali metal tungstates in a melt at 923 K are measured via calorimetry. Standard enthalpies of formation of sought chromates are calculated. The linear correlations between the enthalpies of formation of sulfates, selenates, chromates, tungstates, and molybdates are established, and a linear correlation within - (Δ G o ox)-1-(Δ MV)ox)-1 coordinates is found for isopolymolybdates.

Geomycology. [fungal biosolubilization and accumulation of metals

NASA Technical Reports Server (NTRS)

Puerner, N. J.; Siegel, S. M.

1976-01-01

Fungi have long been known to have capabilities for reduction and alkylation of arsenate and selenate but their general capabilities for solubilizing and accumulating metallic substances have been given serious attention only in recent years. Common members of the Aspergillaceae cultured on boron, copper, lead and other metals or oxides can solubilize and concentrate the elements or their compounds. To account for biosolubilization of the metals, we have set up a model study, incubating selected metals, e.g., mercury, in solutions of various metabolites including L-lysine and citric acid. Results of 100-300 days incubation showed that many metals can in fact be readily solubilized, and in some cases more effectively at pH 6-7 than at pH 1.5-2.

Microbial Transformations of Selenium

PubMed Central

Doran, J. W.; Alexander, M.

1977-01-01

Resting cell suspensions of a strain of Corynebacterium isolated from soil formed dimethyl selenide from selenate, selenite, elemental selenium, selenomethionine, selenocystine, and methaneseleninate. Extracts of the bacterium catalyzed the production of dimethyl selenide from selenite, elemental selenium, and methaneseleninate, and methylation of the inorganic Se compounds was enhanced by S-adenosylmethionine. Neither trimethylselenonium nor methaneselenonate was metabolized by the Corynebacterium. Resting cell suspensions of a methionine-utilizing pseudomonad converted selenomethionine to dimethyl diselenide. Six of 10 microorganisms able to grow on cystine used selenocystine as a sole source of carbon and formed elemental selenium, and one of the isolates, a pseudomonad, was found also to produce selenide. Soil enrichments converted trimethylselenonium to dimethyl selenide. Bacteria capable of utilizing trimethylselenonium, dimethyl selenide, and dimethyl diselenide as carbon sources were isolated from soil. PMID:16345188

Speciation of inorganic selenium and selenoamino acids by an HPLC-UV-HG-AFS system.

PubMed

Ipolyi, I; Corns, W; Stockwell, P; Fodor, P

2001-01-01

For the on-line speciation of selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (SeEt), selenite (Se(IV)) and selenate (Se(VI)), a high-performance liquid chromatography-UV irradiation-hydride generation-atomic fluorescence spectro- metric method is described. Separation was carried out on a conventional reversed-phase C18 column modified with didodecyl- dimethylammonium bromide with gradient elution applying two concentrations of ammonium acetate as the mobile phase. UV irradiation and hydride generation parameters were optimized. The obtained detection limits for SeCys, SeMet, SeEt, Se(IV) and Se(VI) were 0.31, 0.43, 0.7, 0.44 and 0.32 ng ml(-1), respectively, using a 100-microl loop. The method was tested with spiked mineral water and two volunteers' urine samples.

Speciation of inorganic selenium and selenoamino acids by an HPLC-UV-HG-AFS system

PubMed Central

Ipolyi, I.; Corns, W.; Stockwell, P.; Fodor, P.

2001-01-01

For the on-line speciation of selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (SeEt), selenite (Se(IV)) and selenate (Se(VI)), a high-performance liquid chromatography-UV irradiation-hydride generation-atomic fluorescence spectro- metric method is described. Separation was carried out on a conventional reversed-phase C18 column modified with didodecyl- dimethylammonium bromide with gradient elution applying two concentrations of ammonium acetate as the mobile phase. UV irradiation and hydride generation parameters were optimized. The obtained detection limits for SeCys, SeMet, SeEt, Se(IV) and Se(VI) were 0.31, 0.43, 0.7, 0.44 and 0.32 ng ml−1, respectively, using a 100-wl loop. The method was tested with spiked mineral water and two volunteers' urine samples. PMID:18924707

The Kaguya Mission: Present Status and its Lunar Science.

NASA Astrophysics Data System (ADS)

Kato, M.; Takizawa, Y.; Sasaki, S.; Kaguya Team

2009-04-01

Lunar orbiter Kaguya(SELENE) has been successfully launched on September 14, 2007. After insertion into lunar orbit　on October 4 , release of two subsatellites into the elliptical orbits of 100 km perilune, and 2400 km and 800 km apolune, reach the nominal observation orbit with 100 km circular and polar on October 18, and the extension of four sounder antennas with 15 m length and the 12 m mast for magnetometer, and deployment of plasma imager, Kaguya has started nominal observation for ten months on December 21. Most of science instruments show excellent performance for ten months, and continue to acquire their data in extention mission term using saved fuel. New information and insights have been brought to lunar sciences in topography, gravimetry, geology, mineralogy, lithology, plasma physics.

The Influence of Glass Leachate on the Hydraulic, Physical, Mineralogical and Sorptive Properties of Hanford Sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplan, Daniel I.; Serne, R. Jeffrey; Schaef, Herbert T.

2003-08-26

The Immobilized Low Activity Waste (ILAW) generated from the Hanford Site will be disposed of in a vitrified form. It is expected that leachate from the vitrified waste will have a high pH and high ionic strength. The objective of this study was to determine the influence of glass leachate on the hydraulic, physical, mineralogical, and sorptive properties of Hanford sediments. Our approach was to put solutions of NaOH, a simplified surrogate for glass leachate, in contact with quartz sand, a simplified surrogate for the Hanford subsurface sediment, and Warden soil, an actual Hanford sediment. Following contact with three differentmore » concentrations of sodium hydroxide solutions, changes in hydraulic conductivity, porosity, moisture retention, mineralogy, aqueous chemistry, and soil-radionuclide distribution coefficients were determined. Under chemical conditions approaching the most caustic glass leachate conditions predicted in the near-field of the ILAW disposal site, approximated by 0.3 M NaOH, significant changes in mineralogy were observed. The clay minerals of the Hanford sediment evidenced the greatest dissolution thereby increasing the relative proportions of the more resistant minerals, e.g., quartz, feldspar, and calcite, in the remaining mass. Some re-precipitation of solids (mostly amorphous gels) was observed after caustic contact with both solids; these precipitates increased the moisture retention in both sediments, likely because of water retained within the gel coatings. The hydraulic conductivities were slightly lower but, because of experimental artifacts, these reductions should not be considered significant. Thus, there does not seem to be large differences in the hydraulic properties of the quartz sand or Warden silt loam soil after 192 days of contact with caustic fluids similar to glass leachate. The long term projected impact of the increased moisture retention has not been evaluated but likely will not make past simplified performance projections invalid. Despite the fact that some clay minerals, smectites and kaolinite, almost totally dissolved within a year of contact with 3.0 M NaOH (and by inference after longer time frames for 0.3 M NaOH, a more realistic surrogate for ILAW glass leachate) other sorbing minerals such as illite and chlorite do not appreciably react. The net result on sorption of common and risk relevant mobile radionuclides is not expected to be significant. Specifically, little change in Cs-Kd values and a significant increase in Sr-Kd values were measured in the simulated glass leachates versus natural groundwater. The difference in the sorptive responses of the radionuclides was attributed to differences in sorption mechanisms (Cs sorbs strongly to high-energy sites, whereas Sr sorbs primarily by cation exchange but also is sensitive to pH mediated precipitation reactions). Caustic treated sediments contacted with NaOH solutions radiotraced with Sr exhibited high Kd’s likely because of precipitation with CaCO3. In caustic solutions there was no appreciable adsorption for the three anions I-, SeO42-, or TcO4-. In the “far field” vadose zone in past performance projections, some sorption has been allowed for selenate. Even if the caustic glass leachate completely dominates the entire vadose zone below the repository, such that there will be no sorption of selenate, the dilution and pH neutralization that will occur in the upper unconfined aquifer will allow selenate adsorption to occur onto the aquifer sediments. It is recommended that a future performance assessment sensitivity run be performed to address this point.« less

Lunar Dust Monitor for the orbiter of the next Japanese lunar mission SELENE2

NASA Astrophysics Data System (ADS)

Hirai, Takayuki; Sasaki, Sho; Ohashi, Hideo; Kobayashi, Masanori; Fujii, Masayuki; Shibata, Hiromi; Iwai, Takeo; Nogami, Ken-Ichi; Kimura, Hiroshi; Nakamura, Maki

2010-05-01

The next Japanese lunar mission SELENE2, after a successful mission Kaguya (a project named SELENE), is planned to launch in mid 2010 and to consists of a lander, a rover, and an orbiter, as a transmitting satellite to the earth [1]. A dust particle detector is proposed to be onboard the orbiter that is planned to be in operation for one year or more. Dust particles around the Moon include interplanetary dust, beta-meteoroids, interstellar dust, and possibly lunar dust that originate from the subsurface materials of the Moon. It is considered that several tens of thousands of tons of dust particles per year fall onto the Moon and supply materials to its surface layer. "Inflow" and "outflow" dust particles are very important for understanding material compositions of lunar surface. In past missions, dust detectors onboard the Hiten and Nozomi (Hiten-MDC and Nozomi-MDC) measured the flues of dust particles in the lunar orbit [2, 3]. These observations by Hiten- and Nozomi-MDCs created a small dataset of statistics of dust particles excluding earth-orbiting dust once in a week, because the dust detectors had small sensitive areas, 0.01 m2 and 0.014 m^2, respectively. The Lunar Dust EXperiment (LDEX) is designed to map a spatial and temporal variability of the dust size and density distributions in the lunar environment and will be onboard LADEE, which will be launched in 2012 [4]. LDEX will observe the lunar environment for 90 days in a nominal case or for a maximum of 9 months. It has a sensor area of 0.01 m2 at 50 km altitude. For a quantitative study of circumlunar dust, we propose a dust monitoring device with a large aperture size and a large sensor area, called the lunar dust monitor (LDM). The LDM is an impact ionization detector with dimensions 25 cm × 25 cm × 30 cm, and it has a large target (gold-plated Al) of 400 cm^2, to which a high voltage of +500 V is applied. The LDM also has two meshed grids parallel to the target. The grids are 90% transparent: the inner grid is 2 cm apart from the target and the outer grid is 15 cm from the target. We can deduce the mass and velocity information of the impacted dust particle from the recorded signal waveforms generated by the impacts of dust particles. Dust particles around the Moon are classified based on their origins: interstellar dust, interplanetary dust, beta meteoroids, and possibly dust that originated on the Moon. They can be inferred from their kinematic properties: the velocities and the arrival directions. If the proportion of dust components around the Moon is determined by observation, we can increase our knowledge of the contribution of inflow and outflow dust particles to lunar surface materials. References: [1] Matsumoto, K. et al., Joint Annual Meeting of LEAG-ICEUM-SRR (2008) LPI Contribution No.1446, 86. [2] Iglseder H. et al., Adv. Space Res. 17 (1996) 177-182. [3] Sasaki S., et al., Adv. Space Res., 39 (2007), 485-488. [4] Horanyi, M. et al., (2009) LPSC 40th, Abstract #1741.

Comparative effects of selenite and selenate on nitrate assimilation in barley seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Harbit, K. B.; Huffaker, R. C.

1990-01-01

The effect of SeO3= and SeO4= on NO3- assimilation in 8-d-old barley (Hordeum vulgare L.) seedlings was studied over a 24-h period. Selenite at 0.1 mol m-3 in the uptake solutions severely inhibited the induction of NO3- uptake and active nitrate reductases. Selenate, at 1.0 mol m-3 in the nutrient solution, had little effect on induction of activities of these systems until after 12 h; however, when the seedlings were pretreated with 1.0 mol m-3 SeO4= for 24 h, subsequent NO3- uptake from SeO4(=) -free solutions was inhibited about 60%. Sulphate partially alleviated the inhibitory effect of SeO3= when supplied together in the ambient solutions, but had no effect in seedlings pretreated with SeO3=. By contrast, SO4= partially alleviated the inhibitory effect of SeO4= even in seedlings pretreated with SeO4=. Since uptake of NO3- by intact seedlings was also inhibited by SO3=, the percentage of the absorbed NO3- that was reduced was not affected. By contrast, SeO4=, which affected NO3- uptake much less, inhibited the percentage reduced of that absorbed. However, when supplied to detached leaves, both SeO3= and SeO4= inhibited the in vivo reduction of NO3- as well as induction of nitrate reductase and nitrite reductase activities. Selenite was more inhibitory than SeO4= ; approximately a five to 10 times higher concentration of SeO4= than SeO3= was required to achieve similar inhibition. In detached leaves, the inhibitory effect of both SeO3= and SeO4= on in vivo NO3- reduction as well as on the induction of nitrate reductase activity was partially alleviated by SO4=. The inhibitory effects of Se salts on the induction of the nitrite reductase were, however, completely alleviated by SO4=. The results show that in barley seedlings SeO3= is more toxic than SeO4=. The reduction of SeO4= to SeO3= may be a rate limiting step in causing Se toxicity.

Fractionation of selenium isotopes during bacterial respiratory reduction of selenium oxyanions

USGS Publications Warehouse

Herbel, M.J.; Johnson, T.M.; Oremland, R.S.; Bullen, T.D.

2000-01-01

Reduction of selenium oxyanions by microorganisms is an important process in the biogeochemical cycling of selenium. Numerous bacteria can reduce Se oxyanions, which are used as electron acceptors during the oxidation of organic matter in anoxic environments. In this study, we used a double spike (82Se and 74Se) thermal ionization mass spectrometry technique to quantify the isotopic fractionation achieved by three different species of anaerobic bacteria capable of accomplishing growth by respiratory reduction of selenate [SeO42- or Se(VI)] or selenite [SeO32- or Se(IV)] to Se(IV) or elemental selenium [Se(0)] coupled with the oxidation of lactate. Isotopic discrimination in these closed system experiments was evaluated by Rayleigh fractionation equations and numerical models. Growing cultures of Bacillus selenitireducens, a haloalkaliphile capable of growth using Se(IV) as an electron acceptor, induced a 80Se/76Se fractionation of -8.0 ?? 0.4??? (instantaneous ?? value) during reduction of Se(IV) to Se(0). With Bacillus arsenicoselenatis, a haloalkaliphile capable of growth using Se(VI) as an electron acceptor, fractionations of -5.0 ?? 0.5??? and -6.0 ?? 1.0??? were observed for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(0), respectively. In growing cultures of Sulfurospirillum barnesii, a freshwater species capable of growth using Se(VI), fractionation was small initially, but near the end of the log growth phase, it increased to -4.0 ?? 1.0??? and -8.4 ?? 0.4??? for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(O), respectively. Washed cell suspensions of S. barnesii induced fractionations of -1.1 ?? 0.4??? during Se(VI) reduction, and -9.1 ?? 0.5% for Se(IV) reduction, with some evidence for smaller values (e.g., -1.7???) in the earliest-formed Se(0) results. These results demonstrate that dissimilatory reduction of selenate or selenite induces significant isotopic fractionation, and suggest that significant Se isotope ratio variation will be found in nature. Copyright (C) 2000 Elsevier Science Ltd.

Lunar plasma measurement by MAP-PACE onboard KAGUYA (SELENE)

NASA Astrophysics Data System (ADS)

Saito, Yoshifumi

Low energy charged particles around the Moon were vigorously observed by Moon orbiting satellites and plasma instrumentation placed on the lunar surface in 1960s and 1970s. Though there were some satellites that explored the Moon afterwards, most of them were dedicated to the global mapping of the lunar surface. KAGUYA(SELENE) is a Japanese lunar orbiter that studies the origin and evolution of the Moon by means of global mapping of element abundances, mineralogical composition, and surface geographical mapping from 100km altitude. KAGUYA was successfully launched on 14 September 2007 by HIIA launch vehicle from Tanegashima Space Center in Japan. KAGUYA was inserted into a circular lunar polar orbit of 100km altitude and started continuous observation in mid-December 2007. One of the fourteen science instruments MAP-PACE (MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment) was developed for the comprehensive three-dimensional plasma measurement around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measure the distribution function of low energy electrons below 15keV. IMA and IEA measure the distribution function of low energy ions below 28keV/q. IMA has an ability to discriminate the ion mass with high mass resolution. PACE sensors have been measuring solar wind, plasmas in the wake region of the Moon and plasmas in the Earth's magnetosphere. ESA sensors have discovered electron heating over magnetic anomalies on the lunar surface. ESA sensors have also observed electrons accelerated from the lunar surface in the wake region. PACE ion sensors have discovered new features of low energy ions around the Moon. IMA has discovered the existence of alkali ions that are originated from the lunar surface or lunar atmosphere and are picked up by the solar wind. IEA and IMA sensors discovered solar wind reflection by the Moon. PACE ion sensors also discovered that ions are rarefied over the magnetic anomaly on the lunar surface while electrons are heated. MAP-PACE has been revealing unexpectedly active plasma environment around the Moon.

Lemna paucicostata Hegelm. 6746

PubMed Central

Datko, Anne H.; Mudd, S. Harvey; Giovanelli, John

1980-01-01

Photoautotrophic and mixotrophic growth of Lemna paucicostata Hegelm. 6746 (formerly Lemna perpusilla Torr. 6746) was investigated to establish standardized conditions for biochemical studies. Optimal temperature for growth was 29 to 30 C. The medium used previously (Datko AH, Mudd SH, Giovanelli J 1977 J Biol Chem 252: 3436-3445) was modified by inclusion of NH4Cl, decreasing macronutrient and ethylenediamine tetraacetate concentration, increasing micronutrient concentration, and inclusion of bicarbonate (for photoautotrophic growth) or 2-(N-morpholino)ethanesulfonic acid (for mixotrophic growth) buffers. Varying the sulfate concentration between 14 and 1 millimolar had no effect on growth. For photoautotrophic growth in the new medium (medium 4), the effects of CO2 concentration, light intensity, and pH were measured. Under the optimal conditions, a multiplication rate (MR) of 300 to 315, equivalent to a doubling time of 23 to 24 hours was obtained. Addition of glutamine or asparagine did not increase this MR. For mixotrophic growth in low light, the effects of sucrose concentration and pH were determined. Under optimal conditions, MR was 210. A concentration of sucrose less than maximal for growth was chosen for the medium for experiments which will include 14C-labeling of intermediates. MR under these conditions was 184. Growth was equally good in medium 4 and in half-strength Hutner's medium when sulfate was high (0.4 to 1 millimolar), but better in medium 4 when sulfate was low (20 micromolar). Growth rates could be restored to normal in half-strength Hutner's with low sulfate by decreasing the molybdate concentration. By modifying medium 4 to contain very low amounts of sulfate, and by preconditioning medium and plants, it was shown that there was an increment in plant protein of approximately 2.5 micrograms per nanomole of added MgSO4. Colonies undergoing sulfur limitation exhibited a slow growth rate and a high frond to colony ratio. Molybdate and selenate produced growth inhibition reversible by sulfate. Conditions were developed in which the plants could be maintained indefinitely in the presence of either molybdate or selenate in altered metabolic steady-states with lowered growth rates and protein per frond. Images PMID:16661306

Critical evaluation of the ability of sequential extraction procedures to quantify discrete forms of selenium in sediments and soils.

PubMed

Wright, Michael T; Parker, David R; Amrhein, Christopher

2003-10-15

Sequential extraction procedures (SEPs) have been widely used to characterize the mobility, bioavailibility, and potential toxicity of trace elements in soils and sediments. Although oft-criticized, these methods may perform best with redox-labile elements (As, Hg, Se) for which more discrete biogeochemical phases may arise from variations in oxidation number. We critically evaluated two published SEPs for Se for their specificity and precision by applying them to four discrete components in an inert silica matrix: soluble Se(VI) (selenate), Se(IV) (selenite) adsorbed onto goethite, elemental Se, and a metal selenide (FeSe; achavalite). These were extracted both individually and in a mixed model sediment. The more selective of the two procedures was modified to further improve its selectivity (SEP 2M). Both SEP 1 and SEP 2M quantitatively recovered soluble selenate but yielded incomplete recoveries of adsorbed selenite (64% and 81%, respectively). SEP 1 utilizes 0.1 M K2S2O8 to target "organically associated" Se, but this extractant also solubilized most of the elemental (64%) and iron selenide (91%) components of the model sediment. In SEP 2M, the Na2SO3 used in step III is effective in extracting elemental Se but also extracted 17% of the Se from the iron selenide, such that the elemental fraction would be overestimated should both forms coexist. Application of SEP 2M to eight wetland sediments further suggested that the Na2SO3 in step III extracts some organically associated Se, so a NaOH extraction was inserted beforehand to yield a further modification, SEP 2OH. Results using this five-step procedure suggested that the four-step SEP 2M could overestimate elemental Se by as much as 43% due to solubilization of organic Se. Although still imperfect in its selectivity, SEP 20H may be the most suitable procedure for routine, accurate fractionation of Se in soils and sediments. However, the strong oxidant (NaOCl) used in the final step cannot distinguish between refractory organic forms of Se and pyritic Se that might form under sulfur-reducing conditions.

GEMAS: prediction of solid-solution phase partitioning coefficients (Kd) for oxoanions and boric acid in soils using mid-infrared diffuse reflectance spectroscopy.

PubMed

Janik, Leslie J; Forrester, Sean T; Soriano-Disla, José M; Kirby, Jason K; McLaughlin, Michael J; Reimann, Clemens

2015-02-01

The authors' aim was to develop rapid and inexpensive regression models for the prediction of partitioning coefficients (Kd), defined as the ratio of the total or surface-bound metal/metalloid concentration of the solid phase to the total concentration in the solution phase. Values of Kd were measured for boric acid (B[OH]3(0)) and selected added soluble oxoanions: molybdate (MoO4(2-)), antimonate (Sb[OH](6-)), selenate (SeO4(2-)), tellurate (TeO4(2-)) and vanadate (VO4(3-)). Models were developed using approximately 500 spectrally representative soils of the Geochemical Mapping of Agricultural Soils of Europe (GEMAS) program. These calibration soils represented the major properties of the entire 4813 soils of the GEMAS project. Multiple linear regression (MLR) from soil properties, partial least-squares regression (PLSR) using mid-infrared diffuse reflectance Fourier-transformed (DRIFT) spectra, and models using DRIFT spectra plus analytical pH values (DRIFT + pH), were compared with predicted log K(d + 1) values. Apart from selenate (R(2)  = 0.43), the DRIFT + pH calibrations resulted in marginally better models to predict log K(d + 1) values (R(2)  = 0.62-0.79), compared with those from PSLR-DRIFT (R(2)  = 0.61-0.72) and MLR (R(2)  = 0.54-0.79). The DRIFT + pH calibrations were applied to the prediction of log K(d + 1) values in the remaining 4313 soils. An example map of predicted log K(d + 1) values for added soluble MoO4(2-) in soils across Europe is presented. The DRIFT + pH PLSR models provided a rapid and inexpensive tool to assess the risk of mobility and potential availability of boric acid and selected oxoanions in European soils. For these models to be used in the prediction of log K(d + 1) values in soils globally, additional research will be needed to determine if soil variability is accounted on the calibration. © 2014 SETAC.

Temporal variations in dissolved selenium in Lake Kinneret (Israel)

USGS Publications Warehouse

Nishri, A.; Brenner, I.B.; Hall, G.E.M.; Taylor, Howard E.

1999-01-01

Selenium is an essential micronutrient for the growth of the dinoflagellate Peridinium gatunense that dominates the spring algal bloom in Lake Kinneret (LK). The relationship between the levels of dissolved selenium species and the occurance of algal blooms in this lake was studied. During algal blooms of P. gatunense in spring and of the blue-green Aphanizomenon ovalisporum in fall (in 1994) the concentration of epilimnetic dissolved organic Se (Se(org)) increased whereas that of selenite (SeIV) decreased, to levels below the limit of detection: 5 ng/l. The disappearance of SeIV during these blooms is attributed to algal uptake and it is suggested that the growth of both algae may have depended on Se(org) regeneration. A budget performed for selenate (SeVI) suggests that this species is also consumed by algae but to a lesser extent than SeIV (in 1994 ~40% of the epilimnetic load). During the stratification period the hypolimnion of Lake Kinneret becomes anoxic, with high levels of dissolved sulfide. The affects of this environment on the distribution of Se oxy-anions, selenite (SeIV) and selenate(SeVI), were also studied. At the onset of thermal stratification (March) about 35% of the lake inventory of both Se oxidized species are entrapped in the hypolimnion. During stages of oxygen depletion and H2S accumulation, SeIV is completely and SeVI partially removed from this layer. The removal is attributed to reduction followed by formation of particulate reduced products, such as elemental selenium Se(o). The ratio between SeVI to total dissolved selenium (SE(T)) in water sources to the lake is ~0.84, about twice the corresponding ratio in the lake (~0.44, during holomixis). In the lake about 75% of annual SeVI inflow from external sources undergoes reduction to selenide (Se-II) and Se(o) through epilimnetic algal assimilation and hypolimnetic anoxic reduction, respectively. It is suggested that the latter oxidation of the dissolved organic selenide released from biogenic particles and of Se(o) only to the tetravalent species is the cause for the lower ratio of SeVI/Se(T) in the lake.

Ecology and Biotechnology of Selenium-Respiring Bacteria

PubMed Central

2015-01-01

SUMMARY In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications. PMID:25631289

Radio science electron density profiles of lunar ionosphere based on the service module of circumlunar return and reentry spacecraft

NASA Astrophysics Data System (ADS)

Wang, M.; Han, S.; Ping, J.; Tang, G.; Zhang, Q.

2017-09-01

The existence of lunar ionosphere has been under debate for a long time. Radio occultation experiments had been performed by both Luna 19/22 and SELENE missions and electron column density of lunar ionosphere was provided. The Apollo 14 mission also acquired the electron density with in situ measurements. But the results of these missions don't well-matched. In order to explore the lunar ionosphere, radio occultation with the service module of Chinese circumlunar return and reentry spacecraft has been performing. One coherent S-band and X-band radio signals were recorded by China deep space stations, and local correlation was adopted to compute carrier phases of both signals. Based on the above work, the electron density profiles of lunar ionosphere was obtained and analyzed.

Ecology and biotechnology of selenium-respiring bacteria.

PubMed

Nancharaiah, Y V; Lens, P N L

2015-03-01

In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Seeing the Missing Half

NASA Technical Reports Server (NTRS)

Neumann, Gregory A.; Mazarico, Erwan

2009-01-01

The Moon is our closest planetary neighbor and the only extraterrestrial body to which humans have traveled, yet many questions about its origin and early history remain unanswered. Four papers published in this issue by scientific teams of the Japanese SELENE (Kaguya) mission offer a new global view of the Moon that helps to elucidate how the Moon evolved to its present state. The Moon is lopsided: Its visible nearside (tidally locked to face the Earth) is covered with smooth, dark volcanic mare, whereas the farside mainly consists of more heavily cratered, bright highland material. The differences in crustal thickness and density, apparent surface age, composition, and volcanic activity between the two sides are variously ascribed to external causes (such as a giant impact) or to internal causes (such as core formation, mantle convection, and crustal differentiation). The key to resolving these questions will be better data.

Isolation and Metabolic Characteristics of Previously Uncultured Members of the Order Aquificales in a Subsurface Gold Mine

PubMed Central

Takai, Ken; Hirayama, Hisako; Sakihama, Yuri; Inagaki, Fumio; Yamato, Yu; Horikoshi, Koki

2002-01-01

Culture-dependent and -independent techniques were combined to characterize the physiological properties and the ecological impacts of culture-resistant phylotypes of thermophiles within the order Aquificales from a subsurface hot aquifer of a Japanese gold mine. Thermophilic bacteria phylogenetically associated with previously uncultured phylotypes of Aquificales were successfully isolated. 16S ribosomal DNA clone analysis of the entire microbial DNA assemblage and fluorescence in situ whole-cell hybridization analysis indicated that the isolates dominated the microbial population in the subsurface aquifer. The isolates were facultatively anaerobic, hydrogen- or sulfur/thiosulfate-oxidizing, thermophilic chemolithoautotrophs utilizing molecular oxygen, nitrate, ferric iron, arsenate, selenate, and selenite as electron acceptors. Their versatile energy-generating systems may reflect the geochemical conditions of their habitat in the geothermally active subsurface gold mine. PMID:12039766

International Collaboration in Lunar Exploration

NASA Technical Reports Server (NTRS)

Morris, K. Bruce; Horack, John M.; Nall, Mark; Leahy, Bart. D.

2007-01-01

The U.S. Vision for Space Exploration commits the United States to return astronauts to the moon by 2020 using the Ares I Crew Launch Vehicle and Ares V Cargo Launch Vehicle. Like the Apollo program of the 1960s and 1970s, this effort will require preliminary reconnaissance in the form of robotic landers and probes. Unlike Apollo, some of the data NASA will rely upon to select landing sites and conduct science will be based on international missions as well, including SMART-1, SELENE, and Lunar Reconnaissance Orbiter (LRO). Opportunities for international cooperation on the moon also lie in developing lunar exploration technologies. The European Space Agency's SMART-1 orbiter (Figure 1) is making the first comprehensive inventory of key chemical elements in the lunar surface. It is also investigating the impact theory of the moon's formation.'

Direct evidence of void passivation in Cu(InGa)(SSe){sub 2} absorber layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dongho; Kim, Young-Su; Mo, Chan B.

We have investigated the charge collection condition around voids in copper indium gallium sulfur selenide (CIGSSe) solar cells fabricated by sputter and a sequential process of selenization/sulfurization. In this study, we found direct evidence of void passivation by using the junction electron beam induced current method, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The high sulfur concentration at the void surface plays an important role in the performance enhancement of the device. The recombination around voids is effectively suppressed by field-assisted void passivation. Hence, the generated carriers are easily collected by the electrodes. Therefore, when the S/(S + Se)more » ratio at the void surface is over 8% at room temperature, the device performance degradation caused by the recombination at the voids is negligible at the CIGSSe layer.« less

Expanded potential of seleno-carbohydrates as a molecular tool for X-ray structural determination of a carbohydrate-protein complex with single/multi-wavelength anomalous dispersion phasing.

PubMed

Suzuki, Tatsuya; Makyio, Hisayoshi; Ando, Hiromune; Komura, Naoko; Menjo, Masanori; Yamada, Yusuke; Imamura, Akihiro; Ishida, Hideharu; Wakatsuki, Soichi; Kato, Ryuichi; Kiso, Makoto

2014-04-01

Seleno-lactoses have been successfully synthesized as candidates for mimicking carbohydrate ligands for human galectin-9 N-terminal carbohydrate recognition domain (NCRD). Selenium was introduced into the mono- or di-saccharides using p-methylselenobenzoic anhydride (Tol2Se) as a novel selenating reagent. The TolSe-substituted monosaccharides were converted into selenoglycosyl donors or acceptors, which were reacted with coupling partners to afford seleno-lactoses. The seleno-lactoses were converted to the target compounds. The structure of human galectin-9 NCRD co-crystallized with 6-MeSe-lactose was determined with single/multi-wavelength anomalous dispersion (SAD/MAD) phasing and was similar to that of the co-crystal with natural lactose. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sulphur interferes with selenium accumulation in Tartary buckwheat plants.

PubMed

Golob, Aleksandra; Gadžo, Drena; Stibilj, Vekoslava; Djikić, Mirha; Gavrić, Teofil; Kreft, Ivan; Germ, Mateja

2016-11-01

Tartary buckwheat (Fagopyrum tataricum Gaertn.) and common buckwheat (Fagopyrum esculentum Moench.) plants grown in the field were treated foliarly with 126 μM solutions of selenate and/or sulphate in order to study the effect of sulphur (S) on selenium (Se) concentration in plants. In both species, the concentration of Se in all plant parts was similar in control and S treated plants. In Tartary buckwheat the concentration of Se was higher in S and Se treated plants than in plants treated with Se alone. S was shown to enhance Se accumulation in Tartary buckwheat. It was also shown that it is possible to produce grain and herb of Tartary and common buckwheat containing appropriate amounts of Se for food without affecting the yield of the plants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Selenium recovery from kiln powder of cement manufacturing by chemical leaching and bioreduction.

PubMed

Soda, S; Hasegawa, A; Kuroda, M; Hanada, A; Yamashita, M; Ike, M

2015-01-01

A novel process by using chemical leaching followed by bacterial reductive precipitation was proposed for selenium recovery from kiln powder as a byproduct of cement manufacturing. The kiln powder at a slurry concentration of 10 w/v% with 0.25 M Na2CO3 at 28°C produced wastewater containing about 30 mg-Se/L selenium. The wastewater was diluted four-fold and adjusted to pH 8.0 as preconditioning for bioreduction. A bacterial strain Pseudomonas stutzeri NT-I, capable of reducing selenate and selenite into insoluble elemental selenium, could recover about 90% selenium from the preconditioned wastewater containing selenium of 5 mg-Se/L when supplemented with lactate or glycerol. The selenium concentrations in the treated wastewater were low around the regulated effluent concentration of 0.1 mg-Se/L in Japan.

Preliminary observations of the SELENE Gamma Ray Spectrometer

NASA Astrophysics Data System (ADS)

Forni, O.; Diez, B.; Gasnault, O.; Munoz, B.; D'Uston, C.; Reedy, R. C.; Hasebe, N.

2008-09-01

Introduction We analyze the spectra measured by the Gamma Ray Spectrometer (GRS) on board the SELENE satellite [1]. SELENE was inserted in lunar orbit on 4 Oct. 2007. After passing through a health check and a function check, the GRS was shifted to nominal observation on 21 Dec. 2007. The spectra consist in various lines of interest (O, Mg, Al, Si, Ti, Ca, Fe, K, Th, U, and possibly H) superposed on a continuum. The energies of the gamma rays identify the nuclides responsible for the gamma ray emission and their intensities relate to their abundance. Data collected through 17 Feb. 2008 are studied here, corresponding to an accumulation time (Fig. 1) sufficiently good to allow preliminary mapping. Analysis of the global gamma ray spectrum In order to obtain spectra with counting statistics sufficient for peak analysis, we accumulate all observations. The identification of lines is performed on this global lunar spectrum (Fig 2). Fit of individual lines The gamma ray lines that arise from decay of longlived radioactive species are among the easiest to analyze. So far the abundance of two species is studied thanks to such lines: potassium (1461 keV) and thorium (2614 keV). Secondary neutrons from cosmic ray interactions also produce gamma ray when reacting with the planetary material, according to scattering or absorption reactions. However these lines need substantial corrections before an interpretation in terms of abundance can be performed. Lines have been examined with different techniques. The simplest method consists in summing the spectra in a window containing the line of interest. The continuum is adjusted with a polynomial and removed. Such a method was used for the gamma ray spectra collected by Lunar Prospector [2]. This method is especially robust for isolated lines, such as those of K and Th mentioned above, or with very low statistics. The second method consists in fitting the lines by summing a quadratic continuum with Gaussian lines and exponential tails. We presently fit the spectra thanks to a program developed at CESR: Aquarius. Afterwards the areas associated with the parameters of these ideal lines are calculated. This method is welladapted for interfering lines, such as U, Al, and H around 2210 keV, but it requires good statistics. These two methods were used to analyze the Mars Odyssey gamma-ray spectra [3]. Prettyman et al. [4] applied a third method where theoretical spectra are simulated and matched against the observations. Below we propose a fourth approach based on statistical analyzes. Mapping of elemental abundances Data returned by the spacecraft are time-tagged records acquired with a resolution of 17 seconds. The angular distance covered by the spacecraft during this interval corresponds to about 1° at the surface. However the true resolution of the instrument is lower because gamma rays come from all directions onto the spacecraft. The resolution is therefore set by the field of view of the instrument, which depends on the spacecraft altitude and the geometry of the instrument. The full width half maximum of the instrumental response has been estimated to be 130 km at 1 MeV by the SELENE GRS team. We have tiled the data in agreement with the better resolution we could obtain depending on the intensity of a given line. The thorium line at 2614 keV was thus mapped at a resolution of 3° with the first method described above (sum over 2550-2640 keV). Then this map was smoothed with a 5° filter (152 km radius) to approximate the response function of the instrument. Finally the counting rate was converted into abundance (Fig. 3), using the compositions at landing sites and in the highlands as did Gillis et al. [5]. Statistical analysis We have also analysed the data with various multivariate techniques, one of them being the Independent Component Analysis (ICA) [6, 7]. ICA defines a generative model for the observed multivariate data, which is typically given as a large database of samples. In the model, the data variables are assumed to be linear mixtures of some unknown latent variables, and the mixing system is also unknown. The latent variables are assumed non- Gaussian and mutually independent and they are called the independent components of the observed data. These independent components, also called sources or factors, can be found by ICA. This is done by maximising a non-gaussianity criterion of the sources. As in [8], we have used the JADE algorithm developed and described in [9] for our analysis that we focused in the energy range from 750 to 3000 keV. We identify at least three meaningful components. The first one is correlated to the Thorium map (Fig. 4). The corresponding correlation coefficient spectrum exhibits the lines of Thorium, Potassium and Uranium (Fig. 5). The second component (Fig. 6) is clearly correlated with the Iron as shown on its corresponding spectrum (Fig. 5). A third component, identified at lower resolution, seems to be partly correlated with the altitude of the spacecraft (not shown). Further improvement in the data reduction, like corrections for altitude, cosmic ray, and neutron current variations should allow a better interpretation of the data. Acknowledgement. The SELENE GRS team members are: N. Hasebe, O. Okudaira, N. Yamashita, S. Kobayashi, Y. Karouji, M. Hareyama, S. Kodaira, S. Komatsu, K. Hayatsu, K. Iwabuchi, S. Nemoto, E. Shibamura, M.-N. Kobayashi, R.C. Reedy, K.J. Kim, C. d'Uston, S. Maurice, O. Gasnault, O. Forni, B. Diez. References. [1] Hasebe, N. et al. (2008) Earth, Planets and Space, 60, 299-312.. [2] Lawrence, D.J. et al. (1999) Geophys. Res. Lett., 26 (17), 2681-2684. [3] Evans, L.E. et al. (2006) J. Geophys. Res., 111, E03S04. [4] Prettyman, T.H. et al. (2006) J. Geophys. Res., 111, E12007. [5] Gillis, J.J. et al. (2004) Geo. et Cosmo. Acta, 68 (18), 3791-3805. [6] Comon P. (1994) Signal Processing, 36, 287-314. [7] Hyvärinen, A. and E. Oja (2000) Neural Networks, 13(4-5), 411-430. [8] Forni O. et al. (2005) LPSC, 36, 1623 [9] Cardoso, J.-F. (1997) IEEE Letters on Signal Processing, 4, 112-114.

Copper localization, elemental content, and thallus colour in the copper hyperaccumulator lichen Lecanora sierrae from California

USGS Publications Warehouse

Purvis, O.W.; Bennett, J.P.; Spratt, J.

2011-01-01

An unusual dark blue-green lichen, Lecanora sierrae, was discovered over 30 years ago by Czehura near copper mines in the Lights Creek District, Plumas County, Northern California. Using atomic absorption spectroscopy, Czehura found that dark green lichen samples from Warren Canyon contained 4% Cu in ash and suggested that its colour was due to copper accumulation in the cortex. The present study addressed the hypothesis that the green colour in similar material we sampled from Warren Canyon in 2008, is caused by copper localization in the thallus. Optical microscopy and electron microprobe analysis of specimens of L. sierrae confirmed that copper localization took place in the cortex. Elemental analyses of L. sierrae and three other species from the same localities showed high enrichments of copper and selenium, suggesting that copper selenates or selenites might occur in these lichens and be responsible for the unusual colour. Copyright ?? 2011 British Lichen Society.

Copper localization, elemental content, and thallus colour in the copper hyperaccumulator lichen Lecanora sierra from California

USGS Publications Warehouse

Purvis, O.W.; Bennett, J.P.; Spratt, J.

2011-01-01

An unusual dark blue-green lichen, Lecanora sierrae, was discovered over 30 years ago by Czehura near copper mines in the Lights Creek District, Plumas County, Northern California. Using atomic absorption spectroscopy, Czehura found that dark green lichen samples from Warren Canyon contained 4% Cu in ash and suggested that its colour was due to copper accumulation in the cortex. The present study addressed the hypothesis that the green colour in similar material we sampled from Warren Canyon in 2008, is caused by copper localization in the thallus. Optical microscopy and electron microprobe analysis of specimens of L. sierrae confirmed that copper localization took place in the cortex. Elemental analyses of L. sierrae and three other species from the same localities showed high enrichments of copper and selenium, suggesting that copper selenates or selenites might occur in these lichens and be responsible for the unusual colour.

High-quality draft genome sequence of Sedimenticola selenatireducens strain AK4OH1T, a gammaproteobacterium isolated from estuarine sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louie, Tiffany S.; Giovannelli, Donato; Yee, Nathan

Sedimenticola selenatireducens strain AK4OH1 T (= DSM 17993 T = ATCC BAA-1233 T) is a microaerophilic bacterium isolated from sediment from the Arthur Kill intertidal strait between New Jersey and Staten Island, NY. S. selenatireducens is Gram-negative and belongs to the Gammaproteobacteria. Strain AK4OH1 T was the first representative of its genus to be isolated for its unique coupling of the oxidation of aromatic acids to the respiration of selenate. It is a versatile heterotroph and can use a variety of carbon compounds, but can also grow lithoautotrophically under hypoxic and anaerobic conditions. Furthermore, the draft genome comprises 4,588,530 bpmore » and 4276 predicted protein-coding genes including genes for the anaerobic degradation of 4-hydroxybenzoate and benzoate. We report the main features of the genome of S. selenatireducens strain AK4OH1 T.« less

Numerical modelling of impact crater formation associated with isolated lunar skylight candidates on lava tubes

NASA Astrophysics Data System (ADS)

Martellato, E.; Foing, B. H.; Benkhoff, J.

2013-09-01

Skylights are openings on subsurface voids as lava tubes and caves. Recently deep hole structures, possibly skylights, were discovered on lunar photo images by the JAXA SELenological and ENgineering Explorer (SELENE)-Kaguya mission, and successively confirmed by the NASA Lunar Reconnaissance Orbiter (LRO) mission. Vertical hole structures and possibly underlying subsurface voids have high potential as resources for scientific study, and future unmanned and manned activities on the Moon. One mechanism proposed for their formation is impact cratering. The collapse of craters is due to the back spallation phenomena on the rear surface of the lava tube roofs. Previous analysis in this topic was based on small-scales laboratory experiments. These have pointed out that (i) the target thickness-to-crater diameter ratio is 0.7, and (ii) the projectile diameter-to-target thickness ratio is 0.16, at the ballistic limit once extrapolated to planetary conditions.

Speciation of selenium and arsenic compounds by capillary electrophoresis with hydrodynamically modified electroosmotic flow and on-line reduction of selenium(VI) to selenium(IV) with hydride generation inductively coupled plasma mass spectrometric detection.

PubMed

Magnuson, M L; Creed, J T; Brockhoff, C A

1997-10-01

Capillary electrophoresis (CE) with hydride generation inductively coupled plasma mass spectrometry was used to determine four arsenicals and two selenium species. Selenate (SeVI) was reduced on-line to selenite (SeIV) by mixing the CE effluent with concentrated HCl. A microporous PTFE tube was used as a gas-liquid separator to eliminate the 40Ar37Cl and 40Ar35Cl interference from 77Se and 75As, respectively. The direction of the electroosmotic flow during CE was reversed with hydrodynamic pressure, which allowed increased freedom of buffer choice. For conventional pressure injection, method detection limits for SeIV and SeVI based on seven replicate injections were 10 and 24 pg, respectively. Recoveries of SeIV and SeVI in drinking water were measured.

Optoelectrical, structural and morphological characterization of Cu2ZnSnSe4 compound used in photovoltaic applications

NASA Astrophysics Data System (ADS)

Mesa, F.; Leguizamon, A.; Dussan, A.; Gordillo, G.

2016-10-01

In this work, results are reported concerning the effect of the deposition parameters on the structural properties of Cu2ZnSnSe4 (CZTSe) thin films, grown through a chemical reaction of the metallic precursors by co-evaporation in a two-stage process. XRD measurements revealed that the samples deposited by selenization of Cu and Sn grow in the kesterite phase (CZTSe), respectively. Effect of the deposition temperature and mass ratio Cu/ZnSe on the transport properties of CZTSe films were analyzed. It was also found that the electrical conductivity of the thin films is affected by the transport of free carriers in extended states of the conduction band as well as for variable range hopping transport mechanisms, each one predominating in a different temperature range. The molecular and morphological effect on the compound through Raman and AFM measurements was studied.

Potential use of quadrivalent selenium as a systemic deer-browsing repellent: A cautionary note

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jobidon, R.; Prevost, M.

1994-06-01

This study evaluates the potential usefulness and toxicity of applying quadrivalent selenium (selenite ion) to the soil to discourage white-tailed deer from browsing conifer seedlings. After adsorption by the root system and internal transport, organoselenium compounds are volatilized by the foliage, and the characteristic garlic odor is hypothesized to protect coniferous tree seedlings from browsing damage. Results indicate that either 5, 17, or 24 months after treatment, selenized white spruce seedlings did not show significantly different deer-browsing damage from control seedlings when deer numbers were high. Five and seventeen months after treatment, selenium had not leached but had accumulated inmore » the top soil. Large-scale application of selenium may represent a potential environmental risk, hence the authors do not recommend use of selenite ion to prevent damage from deer-browsing of white spruce seedlings.« less

High-quality draft genome sequence of Sedimenticola selenatireducens strain AK4OH1T, a gammaproteobacterium isolated from estuarine sediment

DOE PAGES

Louie, Tiffany S.; Giovannelli, Donato; Yee, Nathan; ...

2016-09-08

Sedimenticola selenatireducens strain AK4OH1 T (= DSM 17993 T = ATCC BAA-1233 T) is a microaerophilic bacterium isolated from sediment from the Arthur Kill intertidal strait between New Jersey and Staten Island, NY. S. selenatireducens is Gram-negative and belongs to the Gammaproteobacteria. Strain AK4OH1 T was the first representative of its genus to be isolated for its unique coupling of the oxidation of aromatic acids to the respiration of selenate. It is a versatile heterotroph and can use a variety of carbon compounds, but can also grow lithoautotrophically under hypoxic and anaerobic conditions. Furthermore, the draft genome comprises 4,588,530 bpmore » and 4276 predicted protein-coding genes including genes for the anaerobic degradation of 4-hydroxybenzoate and benzoate. We report the main features of the genome of S. selenatireducens strain AK4OH1 T.« less

Ring opening of azetidine cycle: First examples of 1-azetidinepropanamine molecules as a template in hybrid organic-inorganic compounds

NASA Astrophysics Data System (ADS)

Gurzhiy, Vladislav V.; Tyumentseva, Olga S.; Britvin, Sergey N.; Krivovichev, Sergey V.; Tananaev, Ivan G.

2018-01-01

Three novel uranyl selenate and sulfate oxysalts templated by protonated azetidine molecules, [AzH]+, and its ring-opened counterpart 1-azetidinepropanamine, [AzH(CH2)3NH3]2+, have been prepared and studied by X-ray structural analysis. Conformations of azetidinium cations were analysed by means of infrared vibrational assignments supported by the DFT calculations. Crystallization of [AzH]2 [(UO2)2(SeO4)3(H2O)] (I) from highly acidic solutions suggests that low pH does not necessarily result in the opening of azetidine ring. [AzH(CH2)3NH3][(UO2)2(SeO4)3(H2O)](H2O) (II) and [AzH(CH2)3NH3](H5O2)[(UO2)2(SO4)3(HSO4)] (III) are the first structurally characterized crystalline compounds bearing isolated ring-opened azetidine moiety.

Plants and microbes assisted selenium nanoparticles: characterization and application

PubMed Central

2014-01-01

Selenium is an essential trace element and is an essential component of many enzymes without which they become inactive. The Se nanoparticles of varying shape and size may be synthesized from Se salts especially selenite and selenates in presence of reducing agents such as proteins, phenols, alcohols and amines. These biomolecules can be used to reduce Se salts in vitro but the byproducts released in the environment may be hazardous to flora and fauna. In this review, therefore, we analysed in depth, the biogenic synthesis of Se nanoparticles, their characterization and transformation into t- Se, m-Se, Se-nanoballs, Se-nanowires and Se-hollow spheres in an innocuous way preventing the environment from pollution. Their shape, size, FTIR, UV–vis, Raman spectra, SEM, TEM images and XRD pattern have been analysed. The weak forces involved in aggregation and transformation of one nano structure into the other have been carefully resolved. PMID:25128031

Spray pyrolysis synthesized Cu(In,Al)(S,Se)2 thin films solar cells

NASA Astrophysics Data System (ADS)

Aamir Hassan, Muhammad; Mujahid, Mohammad; Woei, Leow Shin; Wong, Lydia Helena

2018-03-01

Cu(In,Al)(S,Se)2 thin films are prepared by the Spray pyrolysis of aqueous precursor solutions of copper, indium, aluminium and sulphur sources. The bandgap of the films was engineered by aluminium (Al) doping in CISSe films deposited on molybdenum (Mo) coated glass substrate. The as-sprayed thin films were selenized at 500 °C for 10 min. Cadmium sulphide (CdS) buffer layer was deposited by chemical bath deposition process. Solar cell devices were fabricated with configuration of glass/Mo/CIASSe/CdS/i-ZnO/AZO. The solar cell device containing thin film of Cu(In,Al)(S,Se)2 with our optimized composition shows j-V characteristics of Voc = 0.47 V, jsc = 21.19 mA cm-2, FF = 52.88% and power conversion efficiency of 5.27%, under AM 1.5, 100 mW cm-2 illumination.

Polarized IR-microscope spectra of guanidinium hydrogenselenate single crystal.

PubMed

Drozd, M; Baran, J

2005-10-01

The polarized IR-microscope spectra of C(NH2)3.HSeO4 small single crystal samples were measured at room temperature. The spectra are discussed with the framework of oriented gas model approximation and group theory. The stretching nuOH vibration of the hydrogen bond with the O...O distance of 2.616 A gives characteristic broad AB-type absorption in the IR spectra. The changes of intensity of the AB bands in function of polarizer angle are described. Detailed assignment for bands derived from stretching and bending modes of selenate anions and guanidinium cations were performed. The observed intensities of these bands in polarized infrared spectra were correlated with theoretical calculation of directional cosines of selected transition dipole moments for investigated crystal. The vibrational studies seem to be helpful in understanding of physical and chemical properties of described compound and also in design of new complexes with exactly defined behaviors.

Plants and microbes assisted selenium nanoparticles: characterization and application.

PubMed

Husen, Azamal; Siddiqi, Khwaja Salahuddin

2014-08-16

Selenium is an essential trace element and is an essential component of many enzymes without which they become inactive. The Se nanoparticles of varying shape and size may be synthesized from Se salts especially selenite and selenates in presence of reducing agents such as proteins, phenols, alcohols and amines. These biomolecules can be used to reduce Se salts in vitro but the byproducts released in the environment may be hazardous to flora and fauna. In this review, therefore, we analysed in depth, the biogenic synthesis of Se nanoparticles, their characterization and transformation into t- Se, m-Se, Se-nanoballs, Se-nanowires and Se-hollow spheres in an innocuous way preventing the environment from pollution. Their shape, size, FTIR, UV-vis, Raman spectra, SEM, TEM images and XRD pattern have been analysed. The weak forces involved in aggregation and transformation of one nano structure into the other have been carefully resolved.

Arsenic and selenium in microbial metabolism

USGS Publications Warehouse

Stolz, John F.; Basu, Partha; Santini, Joanne M.; Oremland, Ronald S.

2006-01-01

Arsenic and selenium are readily metabolized by prokaryotes, participating in a full range of metabolic functions including assimilation, methylation, detoxification, and anaerobic respiration. Arsenic speciation and mobility is affected by microbes through oxidation/reduction reactions as part of resistance and respiratory processes. A robust arsenic cycle has been demonstrated in diverse environments. Respiratory arsenate reductases, arsenic methyltransferases, and new components in arsenic resistance have been recently described. The requirement for selenium stems primarily from its incorporation into selenocysteine and its function in selenoenzymes. Selenium oxyanions can serve as an electron acceptor in anaerobic respiration, forming distinct nanoparticles of elemental selenium that may be enriched in (76)Se. The biogenesis of selenoproteins has been elucidated, and selenium methyltransferases and a respiratory selenate reductase have also been described. This review highlights recent advances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.

The membrane biofilm reactor: the natural partnership of membranes and biofilm.

PubMed

Rittmann, B E

2006-01-01

Many exciting new technologies for water-quality control combine microbiological processes with adsorption, advanced oxidation, a membrane or an electrode to improve performance, address emerging contaminants or capture renewable energy. An excellent example is the H2-based membrane biofilm reactor (MBfR), which delivers H2 gas to a biofilm that naturally accumulates on the outer surface of a bubbleless membrane. Autotrophic bacteria in the biofilm oxidise the H2 and use the electrons to reduce NO3-, CIO4- and other oxidised contaminants. This natural partnership of membranes and biofilm makes it possible to gain many cost, performance and simplicity advantages from using H2 as the electron donor for microbially catalysed reductions. The MBfR has been demonstrated for denitrification in drinking water; reduction of perchlorate in groundwater; reduction of selenate, chromate, trichloroethene and other emerging contaminants; advanced N removal in wastewater treatment and autotrophic total-N removal.

Solar-wind proton access deep into the near-Moon wake

NASA Astrophysics Data System (ADS)

Nishino, M. N.; Fujimoto, M.; Maezawa, K.; Saito, Y.; Yokota, S.; Asamura, K.; Tanaka, T.; Tsunakawa, H.; Matsushima, M.; Takahashi, F.; Terasawa, T.; Shibuya, H.; Shimizu, H.

2009-08-01

We study solar wind (SW) entry deep into the near-Moon wake using SELENE (KAGUYA) data. It has been known that SW protons flowing around the Moon access the central region of the distant lunar wake, while their intrusion deep into the near-Moon wake has never been expected. We show that SW protons sneak into the deepest lunar wake (anti-subsolar region at ˜100 km altitude), and that the entry yields strong asymmetry of the near-Moon wake environment. Particle trajectory calculations demonstrate that these SW protons are once scattered at the lunar dayside surface, picked-up by the SW motional electric field, and finally sneak into the deepest wake. Our results mean that the SW protons scattered at the lunar dayside surface and coming into the night side region are crucial for plasma environment in the wake, suggesting absorption of ambient SW electrons into the wake to maintain quasi-neutrality.

Selenium concentrations in waters tributary to and in the vicinity of the Kesterson National Wildlife Refuge, Fresno and Merced counties, California

USGS Publications Warehouse

Presser, T.S.; Barnes, Ivan

1984-01-01

Analyses were made for selenium in waters and other materials of the Kesterson National Wildlife Refuge. Analyses were also made of source agricultural drainage waters from the San Luis Drain discharged into the refuge, and surrounding irrigation supply and return waters. Selenium concentrations range from 140 to 1 ,400 micrograms per liter (microgram/L) in irrigation drain waters supplied to the San Luis Drain. The selenium supplied to the Kesterson National Wildlife Refuge is to a small extent precipitated in sodium sulfate (thenardite) but a higher concentration was found in an alagal mat. Most other waters of the area contain less than detectable < 2 micrograms per liter concentrations of selenium. Oxidation of organic matter and reduction of selenate to selenite were found to be necessary for a quantitative analysis of total selenium. (USGS)

Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

PubMed

Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

2017-11-22

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and completely overwhelmed the diode current at a measurement temperature of 200 °C. This is due to interlayer diffusion of metal that increases the shunt leakage current and decreases the efficiency of the CZTSe thin film solar cells.

Effects of feeding pregnant beef cows selenium-enriched alfalfa hay on selenium status and antibody titers in their newborn calves.

PubMed

Wallace, L G; Bobe, G; Vorachek, W R; Dolan, B P; Estill, C T; Pirelli, G J; Hall, J A

2017-06-01

In newborn dairy calves, it has been demonstrated that supranutritional maternal and colostral Se supplementation using Se yeast or sodium selenite, respectively, improves passive transfer of IgG. In beef cattle, agronomic biofortification with Se is a more practical alternative for Se supplementation, whereby the Se concentration of hay is increased through the use of Se-containing fertilizer amendments. It has been previously demonstrated that agronomic Se biofortification is an effective strategy to improve immunity and performance in Se-replete weaned beef calves. The objective of this experiment was to determine the effects of feeding beef cows Se-enriched alfalfa () hay during the last 8 to 12 wk of gestation on passive transfer of antibodies to calves. At 10 wk ± 16 d before calving, 45 cows were assigned to 1 of 3 treatment groups with 3 pens (5 cows/pen) per treatment: Control cows were fed non-Se-fortified alfalfa hay plus a mineral supplement containing 120 mg/kg Se from sodium selenite, Med-Se cows were fed alfalfa hay fertilized with 45.0 g Se/ha as sodium selenate, and High-Se cows were fed alfalfa hay fertilized with 89.9 g Se/ha as sodium selenate; both the Med-Se and the High-Se groups received mineral supplement without added Se. Colostrum and whole blood (WB) were collected from cows at calving, and WB was collected from calves within 2 h of calving and at 12, 24, 36, and 48 h of age. Concentrations of IgG1 and J-5 antibody in cow colostrum and calf serum were quantified using ELISA procedures. Selenium concentrations linearly increased in WB ( < 0.001) and colostrum ( < 0.001) of cows and in WB of newborn calves ( < 0.001) with increasing Se concentration in alfalfa hay. Colostrum concentrations of IgG1 ( = 0.03) were increased in cows fed Se-biofortified alfalfa hay, but J-5 antibody ( = 0.43) concentrations were not. Calf serum IgG1 ( = 0.43) and J-5 antibody ( = 0.44) concentrations during the first 48 h of age were not affected by prior Se treatment of cows. These data suggest that feeding Se-biofortified alfalfa hay promotes the accumulation of Se and antibodies in colostrum but does not affect short-term serum antibody concentrations in calves.

Laboratory-Scale Bismuth Phosphate Extraction Process Simulation To Track Fate of Fission Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serne, R. JEFFREY; Lindberg, Michael J.; Jones, Thomas E.

2007-02-28

Recent field investigation that collected and characterized vadose zone sediments from beneath inactive liquid disposal facilities at the Hanford 200 Areas show lower than expected concentrations of a long-term risk driver, Tc-99. Therefore laboratory studies were performed to re-create one of the three processes that were used to separate the plutonium from spent fuel and that created most of the wastes disposed or currently stored in tanks at Hanford. The laboratory simulations were used to compare with current estimates based mainly on flow sheet estimates and spotty historical data. Three simulations of the bismuth phosphate precipitation process show that lessmore » that 1% of the Tc-99, Cs-135/137, Sr-90, I-129 carry down with the Pu product and thus these isotopes should have remained within the metals waste streams that after neutralization were sent to single shell tanks. Conversely, these isotopes should not be expected to be found in the first and subsequent cycle waste streams that went to cribs. Measurable quantities (~20 to 30%) of the lanthanides, yttrium, and trivalent actinides (Am and Cm) do precipitate with the Pu product, which is higher than the 10% estimate made for current inventory projections. Surprisingly, Se (added as selenate form) also shows about 10% association with the Pu/bismuth phosphate solids. We speculate that the incorporation of some Se into the bismuth phosphate precipitate is caused by selenate substitution into crystal lattice sites for the phosphate. The bulk of the U daughter product Th-234 and Np-237 daughter product Pa-233 also associate with the solids. We suspect that the Pa daughter products of U (Pa-234 and Pa-231) would also co-precipitate with the bismuth phosphate induced solids. No more than 1 % of the Sr-90 and Sb-125 should carry down with the Pu product that ultimately was purified. Thus the current scheme used to estimate where fission products end up being disposed overestimates by one order of magnitude the partitioning Sr-90, Cs-137, and Sb-125 and by at least two orders of magnitude the portioning of Tc-99 to the first and subsequent cycle waste streams that went to cribs. Conversely, the current scheme underestimates the lanthanide and yttrium fission product quantities that went to cribs by a factor of about 3.« less

Probing Selenium-Ion Distributions and Changes in Redox-State at Biofilm/Mineral Interfaces by Coupling Long-period X-ray Standing Wave and XANES Measurements

NASA Astrophysics Data System (ADS)

Templeton, A. S.; Trainor, T. P.; Spormann, A. M.; Brown, G. E.

2002-12-01

Metal sorption and precipitation reactions at biological as well as mineral surfaces are important controls on metal speciation and bioavailability in natural environments. When highly hydrated biofilms form on mineral surfaces, numerous competitive and synergistic effects are predicted to occur. Experimentally, it is challenging to determine where the sorbed metal ions are localized, the relative affinity of the biological vs. mineral surface sites, or to monitor biomineralization reactions or changes in metal speciation that may also occur. A large part of the difficulty is due to the low concentrations of sorbed ions, the small length-scale of the biofilm-mineral interface, and the complex interplay between microbially-catalayzed redox transformations vs. sorption and/or transport processes. Long-period x-ray standing wave (XSW) techniques are well-suited to determining the vertical distribution of metal(oid) species within biofilms overlying mineral surfaces. We will discuss experiments where Se fluorescence yield profiles are used to compare the affinity of Burkholderia cepacia biofilms for binding Se(IV) and Se(VI) species relative to underlying alpha-Al2O3 substrates over three orders of magnitude in [Se]. In addition, we will discuss how coupling the XSW experiments to grazing-incidence, spatially-resolved Se K-edge XANES spectroscopy can be used to differentiate between the oxidation state of the Se complexes localized within the biofilm vs. the mineral surface. This approach is used to monitor changes in the relative distributions of Se(VI), Se(IV) and Se(0) species as a function of time and proximity to the mineral surface. The long-period XSW data show that selenite preferentially binds to the oxide surfaces, particularly at low [Se]. When B. cepacia is metabolically active, B. cepacia rapidly reduces a fraction of the Se(IV) to the red elemental Se form. In contrast, selenate is preferentially partitioned into the B. cepacia biofilms at all [Se] tested due to a lower affinity for binding to the mineral surface. XANES spectra show that rapid reduction of selenate by B. cepacia to Se(IV) and Se(0) species subsequently results in a vertical segregation of Se species at the B. cepacia/alpha-Al2O3 interface. Elemental Se accumulates within the biofilm with the Se(VI), whereas selenite intermediates preferentially sorb to the underlying oxide surface.

Non-toxic novel route synthesis and characterization of nanocrystalline ZnS{sub x}Se{sub 1−x} thin films with tunable band gap characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agawane, G.L., E-mail: agawaneganesh@gmail.com; Shin, Seung Wook; Vanalakar, S.A.

2014-07-01

Highlights: • A simple, inexpensive, and non-toxic CBD route is used to deposit ZnS thin films. • The ZnS{sub x}Se{sub 1−x} thin films formation takes place via annealing of ZnS thin films in Se atmosphere. • S/(S + Se) ratio found to be temperature dependent and easy tuning of band gap has been done by Se atom deposition. - Abstract: An environmentally benign chemical bath deposition (CBD) route was employed to deposit zinc sulfide (ZnS) thin films. The CBD-ZnS thin films were further selenized in a furnace at various temperatures viz. 200, 300, 400, and 500 °C and the S/(Smore » + Se) ratio was found to be dependent on the annealing temperature. The effects of S/(S + Se) ratio on the structural, compositional and optical properties of the ZnS{sub x}Se{sub 1−x} (ZnSSe) thin films were investigated. EDS analysis showed that the S/(S + Se) ratio decreased from 0.8 to 0.6 when the film annealing temperature increased from 200 to 500 °C. The field emission scanning electron microscopy and atomic force microscopy studies showed that all the films were uniform, pin hole free, smooth, and adhered well to the glass substrate. The X-ray diffraction study on the ZnSSe thin films showed the formation of the cubic phase, except for the unannealed ZnSSe thin film, which showed an amorphous phase. The X-ray photoelectron spectroscopy revealed Zn-S, Zn-Se, and insignificant Zn-OH bonds formation from the Zn 2p{sub 3/2}, S 2p, Se 3d{sub 5/2}, and O 1s atomic states, respectively. The ultraviolet–visible spectroscopy study showed ∼80% transmittance in the visible region for all the ZnSSe thin films having various absorption edges. The tuning of the band gap energy of the ZnSSe thin films was carried out by selenizing CBD-ZnS thin films, and as the S/(S + Se) ratio decreased from 0.8 to 0.6, the band gap energy decreased from 3.20 to 3.12 eV.« less

Global High Resolution Crustal Magnetic Field Mapping at the Surface of the Moon from Lunar Prospector and SELENE/Kaguya Satellites

NASA Astrophysics Data System (ADS)

Ravat, D.; Purucker, M.; Olsen, N.; Finlay, C.

2017-12-01

We derive new models of the lunar crustal magnetic field at the lunar surface with data from Lunar Prospector (LP) and SELENE/Kaguya (K) satellite using a global set of 35820 1° equal area monopoles (O'Brien and Parker, 1994; Olsen et al., 2017). The resulting fields have similar features to surface fields obtained by Tsunakawa et al. (2015) using 230 subset regions and the primary differences are due to our stringent data selection (see below). The use of monopoles allows closer spacing than dipoles with lesser amount of regularization and moderate cluster computer resources. We use the scheme of iteratively reweighted least-squares inversion to compute the initial model. Then the amplitudes of these monopoles are determined by minimizing the misfit to the components together with the global average of |Br| at the ellipsoid surface (i.e. applying a L1 model regularization of Br). In a final step we transform the point-source representation to a spherical harmonic expansion. We extract high quality data segments using a processing scheme based on internal/external dipole field removal, low order polynomial removal, and a new processing scheme called Joint Equivalent Source Cross-validation. In the cross-validation procedure we analyze the fit of modeled components to data in 10° latitudinal segments from an inversion of triplets of nearby passes to a single set of dipoles along the passes. We evaluate the fit using four criteria in each segment: correlation coefficient, amplitude ratio, RMS of the misfit, and standard deviation of field values themselves. We fine-tune the criteria to the choice we would have made in visually retaining pass segments and this yields a global dataset of more than 2.87 million (x 3 components) points at altitudes <60 km. The selected Lunar Prospector and Kaguya magnetic data independently show similar features and statistics for altitudes, observed and modeled components, and their misfit (number of observation locations: LP 1.8 million and K 1.07 million x 3 components). We use these data to make a regional assessment of key magnetic features on the Moon (including impacts and swirls), the depth of magnetization of regional sources, and source parameters of isolated anomalies.

Comparative study of compensation mechanism of lunar impact basins from new gravity field model of SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Namiki, N.; Sugita, S.; Matsumoto, K.; Goossens, S.; Ishihara, Y.; Noda, H.; Ssasaki, S.; Iwata, T.; Hanada, H.; Araki, H.

2009-04-01

The gravity field is a fundamental physical quantity for the study of the internal structure and the evolution of planetary bodies. The most significant problem of the previous lunar gravity models, however, is the lack of direct observations of the far side gravity signals [1]. We then developed a satellite-to-satellite Doppler tracking sub-system for SELENE [2]. In this study, we adopt our new gravity field model with nearly full coverage of the lunar far side to discuss dichotomy of the lunar basins. Because all the nearside impact basins are filled with extensive mare basalt deposits, it is difficult to estimate the subsurface structures, such as uplift of the Moho surface, from gravity measurements. In contrast, far-side impact basins have much less or no mare basalt coverage. This may allow us to investigate the internal structure underneath impact basins. Such knowledge will be important in understanding the response of a solid planetary body to large meteoritic impacts and also the thermal state of the Moon during the late heavy bombardment period. There are distinctive differences between the anomalies of the near side principal mascons and the far side basins. As shown previously [1, 3], the near side principal mascons have sharp shoulders with a gravity plateau and a weakly negative gravity anomaly in the surroundings. In contrast, the far side basins are characterized by concentric rings of positive and negative anomalies. The circular gravity highs agree well with the topographic rims of the basins revealed by SELENE topography model STM-359_grid-02 [4]. In our gravity model, Orientale, Mendel-Rydberg, Lorentz, and Humboldtianum show more affinity with the far side basins than the near side principal mascons [5]. Korolev, Mendeleev, Planck, and Lorentz basins have sharp central peaks of which magnitude in free-air anomalies is almost equivalent to the one in Bouguer anomalies. On the other hand, Orientale, Mendel-Rydberg, Humboldtianum, Moscoviense, and Freundlich-Sharonov basins have a broad peak of which magnitude in free-air anomalies is 20 to 60 % smaller than the one in Bouguer anomalies. We call the former basins Type I and the latter Type II. The central gravity high of Type I basins in Bouguer anomalies suggests the existence of excess mass below the center. Because mare fill is absent from Type I basins, the central gravity high is most likely a manifestation of mantle uplift beneath the basin. The peak height of positive Bouguer anomalies of Type II ranges from 400 to 900 mGal in comparison to those in free-air anomalies from 250 to 500 mGal. This difference can be attributed to local compensation at the center of the Type II basins. We propose a brittle deformation resulting from a load of uplifted mantle. Little relation between the class and formation age is found. On the other hand, there are fewer large lunar basins on the far side. It is unlikely that large impacts concentrated on one side of the Moon and smaller impacts on the other side, as crater diameter depends mostly on impacting energy and momentum, not the properties of the target [6]. A plausible hypothesis is that the primary mascon basins on the near side have deformed more after their initial formation. References: [1] A. S. Konopliv et al., Icarus, 150, 1 (2001). [2] T. Iwata et al., JGSJ, 47, 558 (2001). [3] F. G. Lemoine et al., JGR, 102, 16,339, (1997). [4] H. Araki et al., submitted to Science (2009). [5] N. Namiki et al., accepted by Science (2009). [6] H. J. Melosh, Impact Cratering: A Geologic Process (1989).

Chemical Form of Selenium in Naturally Selenium-Rich Lentils (Lens Culinaris L.) From Saskatchewan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thavarajah, D.; Vandenberg, A.; George, G.N.

2009-06-04

Lentils (Lens culinaris L.) are a source of many essential dietary components and trace elements for human health. In this study we show that lentils grown in the Canadian prairies are additionally enriched in selenium, an essential micronutrient needed for general well-being, including a healthy immune system and protection against cancer. Selenium K near-edge X-ray absorption spectroscopy (XAS) has been used to examine the selenium biochemistry of two lentil cultivars grown in various locations in Saskatchewan, Canada. We observe significant variations in total selenium concentration with geographic location and cultivar; however, almost all the selenium (86--95%) in these field-grown lentilsmore » is present as organic selenium modeled as selenomethionine with a small component (5--14%) as selenate. As the toxicities of certain forms of arsenic and selenium are antagonistic, selenium-rich lentils may have a pivotal role to play in alleviating the chronic arsenic poisoning in Bangladesh.« less

Structure and photoelectrochemistry of silver-copper-indium-diselenide ((AgCu)InSe2) thin film

NASA Astrophysics Data System (ADS)

Zhang, Lin Rui; Li, Tong; Wang, Hao; Pang, Wei; Chen, Yi Chuan; Song, Xue Mei; Zhang, Yong Zhe; Yan, Hui

2018-02-01

In this work, silver (Ag) precursors with different thicknesses were sputtered on the surfaces of CuIn alloys, and (AgCu)InSe2 (ACIS) films were formed after selenization at 550 °C under nitrogen condition using a rapid thermal process furnace. The structure and electrical properties of the ACIS films were investigated. The result showed that the distribution of Ag+ ion was more uniform with increasing the thickness of Ag precursor, and the surface of the thin-film became more homogeneous and denser. When Ag/Cu ratio ≥0.249, the small grain particles disappeared. The band gap can be rationally controlled by adjusting Ag content. When (Ag + Cu)/In ratio ≥ 1.15, the surface of the ACIS thin-film mainly exhibited n-type semiconductor. Through the photoelectrochemistry measurement, it was observed that the incorporation of Ag+ ions could improve photocurrent by adjusting the band gap. With the Ag precursor thickness increased, the dark current decreased at the more negative potential.

Interface engineering of Cu(In,Ga)Se2 and atomic layer deposited Zn(O,S) heterojunctions

NASA Astrophysics Data System (ADS)

Schmidt, Sebastian S.; Merdes, Saoussen; Steigert, Alexander; Klenk, Reiner; Kaufmann, Christian A.; Simsek Sanli, Ekin; van Aken, Peter A.; Oertel, Mike; Schneikart, Anja; Dimmler, Bernhard; Schlatmann, Rutger

2017-08-01

Atomic layer deposition of Zn(O,S) is an attractive dry and Cd-free process for the preparation of buffer layers for chalcopyrite solar modules. As we previously reported, excellent cell and module efficiencies were achieved using absorbers from industrial pilot production. These absorbers were grown using a selenization/sulfurization process. In this contribution we report on the interface engineering required to adapt the process to sulfur-free multi source evaporated absorbers. Different approaches to a local sulfur enrichment at the heterojunction have been studied by using surface analysis (XPS) and scanning transmission electron microscopy. We correlate the microstructure and element distribution at the interface with device properties obtained by electronic characterization. The optimized completely dry process yields cell efficiencies >16% and 30 × 30 cm2 minimodule efficiencies of up to 13.9% on industrial substrates. Any degradation observed in the dry heat stress test is fully reversible after light soaking.

Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry

NASA Astrophysics Data System (ADS)

Nishitsuji, Yohei; Rowe, C. A.; Wapenaar, Kees; Draganov, Deyan

2016-04-01

The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2-2.0 Hz).

Transition from CZTSe to CZTS via multicomponent CZTSSe: Potential low cost photovoltaic absorbers

NASA Astrophysics Data System (ADS)

Chawla, Parul; Jain, Shefali; Vashishtha, Parth; Ahamed, Mansoor; Sharma, Shailesh Narain

2018-01-01

A quintessential perspective for elaborating the pivotal role of quinary chalogenides such as CZTSSe plunges the thrust for exploration of non-vacuum approach for development of multicomponent chalcogenides utilizing organic surfactants and solvents for the nanocrystals ideal for photovoltaic applications. The piece of study envisages employment of TOPO-TOP as capping agents-cum-solvents for the very first time and have not been reported for CZTSSe-based materials till date. The work has been forwarded with the variation of anionic ratios in pristine counterparts of CZTSSe; i.e. CZTSe and CZTS in order to envision the potential of quinary chalcogenides wherein properties of two different materials coalesce to impart improved characteristics in CZTSSe. Varying Se:S ratios gradually during nanocrystals' synthesis by high-temperature colloidal route ensued precise control over the phase formation and morphology. With the employment of these capping agents, as-synthesized nanocrystals' are inherently Se-rich and high crystallinity restrains the need for selenization and high temperature annnealing respectively.

Band-limited Bouguer gravity identifies new basins on the Moon

NASA Astrophysics Data System (ADS)

Featherstone, W. E.; Hirt, C.; Kuhn, M.

2013-06-01

Spectral domain forward modeling is used to generate topography-implied gravity for the Moon using data from the Lunar Orbiter Laser Altimeter instrument operated on board the Lunar Reconnaissance Orbiter mission. This is subtracted from Selenological and Engineering Explorer (SELENE)-derived gravity to generate band-limited Bouguer gravity maps of the Moon so as to enhance the gravitational signatures of anomalous mass densities nearer the surface. This procedure adds evidence that two previously postulated basins on the lunar farside, Fitzgerald-Jackson (25°N, 191°E) and to the east of Debye (50°N, 180°E), are indeed real. When applied over the entire lunar surface, band-limited Bouguer gravity reveals the locations of 280 candidate basins that have not been identified when using full-spectrum gravity or topography alone, showing the approach to be of utility. Of the 280 basins, 66 are classified as distinct from their band-limited Bouguer gravity and topographic signatures, making them worthy of further investigation.

Space Weathering of the Lunar Surface by Solar Wind Particles

NASA Astrophysics Data System (ADS)

Kim, Sungsoo S.; Sim, Chaekyung

2017-08-01

The lunar regolith is space-weathered to a different degree in response to the different fluxes of incident solar wind particles and micrometeoroids. Crater walls, among other slating surfaces, are good tracers of the space-weathering process because they mature differently depending on the varying incident angles of weathering agents. We divide a crater wall into four quadrants (north, south, east, and west) and analyze the distribution of 950-nm/750-nm reflectance-ratio and 750-nm reflectance values in each wall quadrant, using the topography-corrected images by Multispectral Imager (MI) onboard SELENE (Kaguya). For thousands of impact craters across the Moon, we interpret the spectral distributions in the four wall quadrants in terms of the space weathering by solar wind particles and micrometeoroids and of gardening by meteroids. We take into account the solar-wind shielding by the Earth’s magnetotail to correctly assess the different spectral behaviors between east- and west-facing walls of the craters in the near-side of the Moon.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2007

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2007-01-01

This report presents the results for two sampling periods during a 4-year monitoring survey to provide a characterization of selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species, and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species-western mosquitofish (Gambusia affinis), and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Total selenium concentrations in water for both sampling periods ranged from 1.43 to 47.1 micrograms per liter, predominately as selenate, which is typical of waters leached out of selenium-contaminated marine shales under alkaline and oxidizing conditions. Total selenium concentrations ranged from 0.88 to 20.2 micrograms per gram in biota, and from 0.15 to 28.9 micrograms per gram in detritus and sediment.

Lunar surface exploration using mobile robots

NASA Astrophysics Data System (ADS)

Nishida, Shin-Ichiro; Wakabayashi, Sachiko

2012-06-01

A lunar exploration architecture study is being carried out by space agencies. JAXA is carrying out research and development of a mobile robot (rover) to be deployed on the lunar surface for exploration and outpost construction. The main target areas for outpost construction and lunar exploration are mountainous zones. The moon's surface is covered by regolith. Achieving a steady traversal of such irregular terrain constitutes the major technical problem for rovers. A newly developed lightweight crawler mechanism can effectively traverse such irregular terrain because of its low contact force with the ground. This fact was determined on the basis of the mass and expected payload of the rover. This paper describes a plan for Japanese lunar surface exploration using mobile robots, and presents the results of testing and analysis needed in their development. This paper also gives an overview of the lunar exploration robot to be deployed in the SELENE follow-on mission, and the composition of its mobility, navigation, and control systems.

Effects of Different Forms of Selenium Fertilizers on Se Accumulation, Distribution, and Residual Effect in Winter Wheat-Summer Maize Rotation System.

PubMed

Wang, Qi; Yu, Yao; Li, Jixiang; Wan, Yanan; Huang, Qingqing; Guo, Yanbin; Li, Huafen

2017-02-15

Foliar Se fertilizers were applied to investigate the effects of Se forms on Se accumulation and distribution in the wheat-maize rotation system and residual concentration of Se in subsequent crops. Sodium selenite, sodium selenate, selenomethionine, chemical nano-Se, humic acid + sodium selenite, and compound fertilizer + sodium selenite were applied once at the flowering stage of wheat (30 g ha -1 ) and at the bell stage of maize (60 g ha -1 ). Compared with the control treatment, foliar Se applications significant increased the grain Se concentration of wheat and maize by 0.02-0.31 and 0.07-1.09 mg kg -1 , respectively. Wheat and maize grain Se recoveries were 3.0-10.4 and 4.1-18.5%, respectively. However, Se concentrations in the grain of subsequent wheat and maize significantly decreased by 77.9 and 91.2%, respectively. The change of Se concentration in soil was a dynamic process with Se depletion after harvest of maize.

Effects of pH and anions on the sorption of selenium ions onto magnetite.

PubMed

Kim, Seung Soo; Min, Je Ho; Lee, Jae Kwang; Baik, Min Hoon; Choi, Jong-Won; Shin, Hyung Seon

2012-02-01

This study analyzes the influence of carbonate and silicate, which are generally abundant in granitic groundwater, on the sorption of selenium ions onto magnetite in order to understand the behaviors of selenium in a radioactive waste repository. Selenite was sorbed onto magnetite very well below pH 10, but silicate and carbonate hindered the sorption of selenite onto magnetite. On the other hand, little selenate was sorbed onto magnetite in neutral and weak alkaline solutions of 0.02 M NaNO(3) or NaClO(4), matching the ionic strength in a granitic groundwater, even though silicate or carbonate was not contained in the solutions. The surface complexation constants between selenite and magnetite were obtained by using a geochemical program, FITEQL 4.0, from the experimental data, and the formation of an inner-sphere surface complex such as =FeOSeO(2)(-) was suggested for the sorption of selenite onto magnetite from the diffuse double layer model calculation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Implications for the origins of pure anorthosites found in the feldspathic lunar meteorites, Dhofar 489 group

NASA Astrophysics Data System (ADS)

Nagaoka, Hiroshi; Takeda, Hiroshi; Karouji, Yuzuru; Ohtake, Makiko; Yamaguchi, Akira; Yoneda, Shigekazu; Hasebe, Nobuyuki

2014-12-01

Remote observation by the reflectance spectrometers onboard the Japanese lunar explorer Kaguya (SELENE) showed the purest anorthosite (PAN) spots (>98% plagioclase) at some large craters. Mineralogical and petrologic investigations on the feldspathic lunar meteorites, Dhofar 489 and Dhofar 911, revealed the presence of several pure anorthosite clasts. A comparison with Apollo nearside samples of ferroan anorthosite (FAN) indicated that of the FAN samples returned by the Apollo missions, sample 60015 is the largest anorthosite with the highest plagioclase abundance and homogeneous mafic mineral compositions. These pure anorthosites (>98% plagioclase) have large chemical variations in Mg number (Mg# = molar 100 × Mg/(Mg + Fe)) of each coexisting mafic mineral. The variations imply that these pure anorthosites underwent complex formation processes and were not formed by simple flotation of plagioclase. The lunar highland samples with pure anorthosite and the PAN observed by Kaguya suggest that pure anorthosite is widely distributed as lunar crust lithology over the entire Moon.

Selenium Biofortification in Rice ( Oryza sativa L.) Sprouting: Effects on Se Yield and Nutritional Traits with Focus on Phenolic Acid Profile.

PubMed

D'Amato, Roberto; Fontanella, Maria Chiara; Falcinelli, Beatrice; Beone, Gian Maria; Bravi, Elisabetta; Marconi, Ombretta; Benincasa, Paolo; Businelli, Daniela

2018-04-25

The contents of total Se and of inorganic and organic Se species, as well as the contents of proteins, chlorophylls, carotenoids, and phenolic acids, were measured in 10-day old sprouts of rice ( Oryza sativa L.) obtained with increasing levels (15, 45, 135, and 405 mg Se L -1 ) of sodium selenite and sodium selenate and with distilled water as control. Increasing Se levels increased organic and inorganic Se contents of sprouts, as well as the content of phenolic acids, especially in their soluble conjugated forms. Moderate levels of sodium selenite (i.e., not higher that 45 mg L -1 ) appeared the best compromise to obtain high Se and phenolic acid yields together with high proportion of organic Se while limiting residual Se in the germination substrate waste. Se biofortification of rice sprouts appears a feasible and efficient way to promote Se and phenolic acid intake in human diet, with well-known health benefits.

The preparation of three selenium-containing Cordyceps militaris polysaccharides: Characterization and anti-tumor activities.

PubMed

Liu, Fei; Zhu, Zhen-Yuan; Sun, Xiaoli; Gao, Hui; Zhang, Yong-Min

2017-06-01

In the present work, three fractions of selenized Cordyceps militaris polysaccharides (SeCPS) named SeCPS- I, SeCPS- II and SeCPS- III were isolated and purified by ultra-filtration. Their selenium content were measured as 541.3, 863.7 and 623.3μg/g respectively by a graphite furnace atomic absorption spectroscopy. The monosaccharide comformation analysis showed that they were mainly consisted of D-Mannose, D-Glucose, and D-Galactose in mole ratios of 1:7.63:0.83, 1:1.34:0.31 and 1:3.77:0.41 respectively. Their structure characteristics were compared by IFR and NMR spectroscopy. Scanning electron microscopy (SEM) and Congo red (CR) spectrophotometric method were used to investigate their morphological characteristics and conformational transition. SeCPS-II showed the strongest anti-tumor effects judging from the result of in vitro anti-tumor assays against two tumor cell lines (hepatocellular carcinoma HepG-2 cells and lung adenocarcinom A549 cells). Copyright © 2017 Elsevier B.V. All rights reserved.

Celebrating Two Centuries of Research in Selenium Chemistry: State of the Art and New Prospective.

PubMed

Santi, Claudio; Bagnoli, Luana

2017-12-02

In 2017, the 200th anniversary of the discovery of selenium was celebrated. In 1817, the Swedish chemists, Berzelius and Gahn, on roasting 200 kg of sulfur from a pyrite from the Falun mine, obtained about 3 g of a precipitate that they first wrongly identified as tellurium. Berzelius doubted this result and repeated the analysis some months later realizing that a new element was in his hands and he named this element Selenium (Greek: Selene, moon) in consideration of its resemblance to Tellurium (Latin: Tellus, earth). Several events were organized in the year for this special celebration and this Special Issue would like to be an additional contribution to the success of a research that, especially during the last decades, rapidly grew in different fields: synthesis, medicinal chemistry, biology, material, and environment. These studies are strongly characterized by multi- and interdisciplinary connections, and, for this reason, we collected here contributions coming from different areas and disciplines, not exclusively synthetic organic chemistry.

The Kaguya Mission: Science Achievements and Data Release

NASA Astrophysics Data System (ADS)

Kato, Manabu; Sasaki, Susumu; Takizawa, Yoshisada

2010-05-01

Lunar orbiter Kaguya (SELENE) has impacted the Moon on July 10, 2009. The Kaguya mission has completed to observe the whole Moon for total twenty months; checkout term of three months, nominal one of ten months, and the extension of seven months. In the extended mission before the impact the measurements of magnetic field and gamma-ray from lower orbits have been perrformed successfully in addition to low altitude observation by Terraine Camera, Multiband Imager, and HDTV Camera. New data of intense magnetic anomaly and GRS data with higher spacial resolution has been acquired to study elemental distribution and magnetism of the Moon. New information and insights have been brought to lunar sciences in topography, gra-vimetry, geology, mineralogy, lithology, plasma physics. On November 1, 2009 the Kaguya team has released science data to the public as an international promise. The archive data can be accessed through Kaguya homepage of JAXA. Image gallary and 3D GIS system have been also put on view from the same homepage.

A lunar construction shack vehicle: Final design

NASA Technical Reports Server (NTRS)

1988-01-01

A lunar construction shack vehicle is a critical component in most of the plans proposed for the construction of a permanent base on the moon. The Selene Engineering Company (SEC) has developed a concept for this vehicle which is both innovative and practical. The design makes use of the most advanced technology available to meet the goals for a safe, versatile and durable habitat that will serve as a starting point for the initial phase of the construction of a permanent lunar base. This document outlines SEC's proposed design for a lander vehicle which will be fully self-sufficient and will provide for all necessary life support, including consumables and radiation protection, needed by the construction crew until they can complete the assembly of a more permanent habitat. Since it is highly likely that it will take more than one crew to complete the construction of a permanent lunar base, the design emphasis is on systems which can be easily maintained and resupplied and which will take a minimum of start up preparation by succeeding crews.

Selenium delays tomato fruit ripening by inhibiting ethylene biosynthesis and enhancing the antioxidant defense system.

PubMed

Zhu, Zhu; Chen, Yanli; Shi, Guoqing; Zhang, Xueji

2017-03-15

The antioxidant activity of selenium (Se) detoxifies reactive oxygen species (ROS) in plants and animals. In the present study, we elucidated the mechanism underlying Se induced fruit development and ripening. Our study showed that foliar pretreatment with 1mgL -1 sodium selenate effectively delayed fruit ripening and maintained fruit quality. Gene expression studies revealed that the repression of ethylene biosynthetic genes 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase decreased ethylene production and respiration rate. Moreover, Se treatment probably boosted the antioxidant defense system to reduce ROS generation and membrane damage. The enhanced antioxidative effect was attributed to higher glutathione content and increased activity of enzymes such as glutathione peroxidase and glutathione reductase. The upregulation of respiratory burst oxidase homologue genes in tomato fruit may also contribute to the enhanced antioxidative effect. Selenium treatment represents a promising strategy for delaying ripening and extending the shelf life of tomato fruit. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of selenium accumulation on phytotoxicity, herbivory, and pollination ecology in radish (Raphanus sativus L.).

PubMed

Hladun, Kristen R; Parker, David R; Tran, Khoa D; Trumble, John T

2013-01-01

Selenium (Se) has contaminated areas in the western USA where pollination is critical to the functioning of both agricultural and natural ecosystems, yet we know little about how Se can impact pollinators. In a two-year semi-field study, the weedy plant Raphanus sativus (radish) was exposed to three selenate treatments and two pollination treatments to evaluate the effects on pollinator-plant interactions. Honey bee (Apis mellifera L.) pollinators were observed to readily forage on R. sativus for both pollen and nectar despite high floral Se concentrations. Se treatment increased both seed abortion (14%) and decreased plant biomass (8-9%). Herbivory by birds and aphids was reduced on Se-treated plants, indicating a potential reproductive advantage for the plant. Our study sheds light on how pollutants such as Se can impact the pollination ecology of a plant that accumulates even moderate amounts of Se. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of nationwide addition of selenium to fertilizers on foods, and animal and human health in Finland: From deficiency to optimal selenium status of the population.

PubMed

Alfthan, Georg; Eurola, Merja; Ekholm, Päivi; Venäläinen, Eija-Riitta; Root, Tarja; Korkalainen, Katja; Hartikainen, Helinä; Salminen, Pirjo; Hietaniemi, Veli; Aspila, Pentti; Aro, Antti

2015-01-01

Despite different geological features the Nordic countries are generally selenium-poor areas. In each country various factors such as food importation and life-style determine the selenium (Se) intake. Due to an extremely low Se intake in the 1970s in Finland, 0.025 mg/day, an official decision was made in 1984 to supplement multinutrient fertilizers with Se in the chemical form of sodium selenate. Almost all fertilizers used in Finland since 1985 have contained Se. Currently all crop fertilizers contain 15 mg Se/kg. Finland is still the only country to take this country-wide measure. In a national monitoring programme, sampling of cereals, basic foodstuffs, feeds, fertilizers, soils, and human tissues has been carried out annually since 1985 by four governmental research organizations. Sampling of foods has been done four times per year and human blood has been obtained annually from the same (n=60) adults. The accuracy of analyses has been verified by annual interlaboratory quality control. During this programme the selenium concentration of spring cereals has increased on average 15-fold compared with the level before the Se fertilization. The mean increase in the Se concentration in beef, pork and milk was 6-, 2- and 3-fold. In terms of Se, organically grown foods of plant origin are generally comparable to products produced before the Se supplementation of fertilizers. Milk from organically fed cows is 50% lower in Se than the usual milk. The average dietary human intake increased from 0.04 mg Se/day/10 MJ in 1985 to a present plateau of 0.08 mg Se/day/10 MJ, which is well above the current nutrition recommendations. Foods of animal origin contribute over 70% of the total daily Se intake. The mean human plasma Se concentration increased from 0.89 μmol/L to a general level of 1.40 μmol/L that can be considered to be an optimal status. The absence of Se deficiency diseases and a reference population have made conclusions on the impact on human health difficult. However, the rates of cardiovascular diseases and cancers have remained similar during the pre- and post-supplementation indicating medical and life-style factors to be much stronger determinants than Se. The nationwide supplementation of fertilizers with sodium selenate is shown to be effective and safe in increasing the Se intake of the whole population. Also, the health of animals has improved. Copyright © 2014 Elsevier GmbH. All rights reserved.

Cu(In,Ga)Se2 thin films annealed using a continuous wave Nd:YAG laser (λ0 = 532 nm): Effects of laser-annealing time

NASA Astrophysics Data System (ADS)

Yoo, Myoung Han; Ko, Pil Ju; Kim, Nam-Hoon; Lee, Hyun-Yong

2017-12-01

Preparation of Cu(In,Ga)Se2 (CIGS) thin films has continued to face problems related to the selenization of sputtered Cu-In-Ga precursors when using H2Se vapor in that the materials are highly toxic and the facilities extremely costly. Another obstacle facing the production of CIGS thin films has been the required annealing temperature, as it relates to the decomposition temperature of a typical flexible polymer substrate. A novel laser-annealing process for CIGS thin films, which does not involve the selenization process and which can be performed at a lower temperature, has been proposed. Following sputtering with a Cu0.9In0.7Ga0.3Se2 target, the laser-annealing of the CIGS thin film was performed using a continuous 532-nm Nd:YAG laser with an annealing time of 200 - 1000 s at a laser optical power of 2.75 W. CIGS chalcopyrite (112), (220/204), and (312/116) phases, with some weak diffraction peaks corresponding to the Cu-Se- or the In-Se-related phases, were successfully obtained for all the CIGS thin films that had been laser-annealed at 2.75 W. The lattice parameters, the d-spacing, the tetragonal distortion parameter, and the strain led to the crystallinity being worse and grain size being smaller at 600 s while better crystallinity was obtained at 200 and 800 s, which was closely related to the deviations from molecularity and stoichiometry, which were greatest at 600 s while the values exhibited near-stoichiometric compositions at 200 and 800 s. The band gaps of the laser-annealed CIGS thin films were within a range of 1.765 - 1.977 eV and depended on the internal stress. The mean absorbance of the laser-annealed CIGS thin films was within a range of 1.598 - 1.900, suggesting that approximately 97.47 - 98.74% of the incident photons in the visible spectral region were absorbed by this 400-nm film. The conductivity types exhibited the same deviations (Δ m > 0 and Δ s < 0) in all the laser-annealed CIGS thin films. After laser-annealing, the resistivity fell abruptly to a range of 3.551 × 10 -2 - 1.022 × 10 -1 Ω·cm. The carrier concentration was on the order of 1019 - 1021 cm -3, and the carrier mobility was 5.7 × 10 -2 - 5.7 × 100 cm2/V·s.

Dietary selenium disrupts hepatic triglyceride stores and transcriptional networks associated with growth and Notch signaling in juvenile rainbow trout.

PubMed

Knight, Rosalinda; Marlatt, Vicki L; Baker, Josh A; Lo, Bonnie P; deBruyn, Adrian M H; Elphick, James R; Martyniuk, Christopher J

2016-11-01

Dietary Se has been shown to adversely affect adult fish by altering growth rates and metabolism. To determine the underlying mechanisms associated with these observations, we measured biochemical and transcriptomic endpoints in rainbow trout following dietary Se exposures. Treatment groups of juvenile rainbow trout were fed either control Lumbriculus variegatus worms or worms cultured on selenized yeast. Selenized yeast was cultured at four nominal doses of 5, 10, 20 or 40mg/kg Se dry weight (measured dose in the worms of 7.1, 10.7, 19.5, and 31.8mg/kgSedw respectively) and fish were fed for 60days. At 60 d, hepatic triglycerides, glycogen, total glutathione, 8-isoprostane and the transcriptome response in the liver (n=8/group) were measured. Fish fed the nominal dose of 20 and 40mg/kg Se dry weight had lower body weight and a shorter length, as well as lower triglyceride in the liver compared to controls. Evidence was lacking for an oxidative stress response and there was no change in total glutathione, 8-isoprostane levels, nor relative mRNA levels for glutathione peroxidase isoforms among groups. Microarray analysis revealed that molecular networks for long-chain fatty acid transport, lipid transport, and low density lipid oxidation were increased in the liver of fish fed 40mg/kg, and this is hypothesized to be associated with the lower triglyceride levels in these fish. In addition, up-regulated gene networks in the liver of 40mg/kg Se treated fish included epidermal growth factor receptor signaling, growth hormone receptor, and insulin growth factor receptor 1 signaling pathways. These molecular changes are hypothesized to be compensatory and related to impaired growth. A gene network related to Notch signaling, which is involved in cell-cell communication and gene transcription regulation, was also increased in the liver following dietary treatments with both 20 and 40mg/kg Se. Transcriptomic data support the hypothesis that dietary Se increases the expression of networks for growth-related signaling cascades in addition to those related to fatty acid synthesis and metabolism. We propose that the disruption of metabolites related to triglyceride processing and storage, as well as gene networks for epidermal growth factor and Notch signaling in the liver, represent key molecular initiating events for adverse outcomes related to growth and Se toxicity in fish. Copyright © 2016 Elsevier B.V. All rights reserved.

HEKATE-A novel grazing incidence neutron scattering concept for the European Spallation Source.

PubMed

Glavic, Artur; Stahn, Jochen

2018-03-01

Structure and magnetism at surfaces and buried interfaces on the nanoscale can only be accessed by few techniques, one of which is grazing incidence neutron scattering. While the technique has its strongest limitation in a low signal and large background, due to the low scattering probability and need for high resolution, it can be expected that the high intensity of the European Spallation Source in Lund, Sweden, will make many more such studies possible, warranting a dedicated beamline for this technique. We present an instrument concept, Highly Extended K range And Tunable Experiment (HEKATE), for surface scattering that combines the advantages of two Selene neutron guides with unique capabilities of spatially separated distinct wavelength frames. With this combination, it is not only possible to measure large specular reflectometry ranges, even on free liquid surfaces, but also to use two independent incident beams with tunable sizes and resolutions that can be optimized for the specifics of the investigated samples. Further the instrument guide geometry is tuned for reduction of high energy particle background and only uses low to moderate supermirror coatings for high reliability and affordable cost.

HEKATE—A novel grazing incidence neutron scattering concept for the European Spallation Source

NASA Astrophysics Data System (ADS)

Glavic, Artur; Stahn, Jochen

2018-03-01

Structure and magnetism at surfaces and buried interfaces on the nanoscale can only be accessed by few techniques, one of which is grazing incidence neutron scattering. While the technique has its strongest limitation in a low signal and large background, due to the low scattering probability and need for high resolution, it can be expected that the high intensity of the European Spallation Source in Lund, Sweden, will make many more such studies possible, warranting a dedicated beamline for this technique. We present an instrument concept, Highly Extended K range And Tunable Experiment (HEKATE), for surface scattering that combines the advantages of two Selene neutron guides with unique capabilities of spatially separated distinct wavelength frames. With this combination, it is not only possible to measure large specular reflectometry ranges, even on free liquid surfaces, but also to use two independent incident beams with tunable sizes and resolutions that can be optimized for the specifics of the investigated samples. Further the instrument guide geometry is tuned for reduction of high energy particle background and only uses low to moderate supermirror coatings for high reliability and affordable cost.

Large-area synthesis and photoelectric properties of few-layer MoSe2 on molybdenum foils

NASA Astrophysics Data System (ADS)

Wu, Zenghui; Tai, Guoan; Wang, Xufeng; Hu, Tingsong; Wang, Rui; Guo, Wanlin

2018-03-01

Compared with MoS2 and WS2, selenide analogs have narrower band gaps and higher electron mobilities, which make them more applicable to real electrical devices. In addition, few-layer metal selenides have higher electrical conductivity, carrier mobility and light absorption than the corresponding monolayers. However, the large-scale and high-quality growth of few-layer metal selenides remains a significant challenge. Here, we develop a facile method to grow large-area and highly crystalline few-layer MoSe2 by directly selenizing the Mo foil surface at 550 °C within 60 min under ambient pressure. The atomic layers were controllably grown with thicknesses between 3.4 and 6 nm, which just met the thickness range required for high-performance electrical devices. Furthermore, we fabricated a vertical p-n junction photodetector composed of few-layer MoSe2 and p-type silicon, achieving photoresponsivity higher by two orders of magnitude than that of the reported monolayer counterpart. This technique provides a feasible approach towards preparing other 2D transition metal dichalcogendes for device applications.

Relation of pH and other soil variables to concentrations of Pb, Cu, Zn, Cd, and Se in earthworms

USGS Publications Warehouse

Beyer, W.N.; Hensler, G.L.; Moore, J.

1987-01-01

Various soil treatments (clay, composted peat, superphosphate, sulfur, calcium carbonate, calcium chloride, zinc chloride, selenous acid) were added to experimental field plots to test the effect of different soil variables on the concentrations of 5 elements in earthworms (Pb, Cu, Zn, Cd, Se). Concentrations of the 5 elements were related to 9 soil variables (soil Pb, soil Cu, soil Zn, pH, organic matter, P, K, Mg, and Ca) with linear multiple regression. Lead concentrations in earthworms were positively correlated with soil Pb and soil organic matter, and negatively correlated with soil pH and soil Mg, with an R2 of 64%. Se concentrations were higher in earthworms from plots amended with Se, and Zn concentrations were higher in earthworms from plots amended with Zn. However, none of the other soil variables had important effects on the concentrations of Cu, Zn, Cd and Se in earthworms. Although some significant statistical relations were demonstrated, the values of r2 of all relations (> 20%) were so low that they had little predictive value.

Strategy of Planetary Data Archives in Japanese Missions for Planetary Data System

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Ishihara, Y.; Murakami, S. Y.

2017-12-01

To preserve data acquired by Japanese planetary explorations for a long time, we need a data archiving strategy in a form suitable for resources. Planetary Data System(PDS) developed by NASA is an excellent system for saving data over a long period. Especially for the current version 4 (PDS4), it is possible to create a data archive with high completeness using information technology. Historically, the Japanese planetary missions have archived data by scientists in their ways, but in the past decade, JAXA has been aiming to conform data to PDS considering long term preservation. Hayabusa, Akatsuki are archived in PDS3. Kaguya(SELENE) data have been newly converted from the original format to PDS3. Hayabusa2 and BepiColombo, and future planetary explorations will release data in PDS4. The cooperation of engineers who are familiar with information technology is indispensable to create data archives for scientists. In addition, it is essential to have experience, information sharing, and a system to support it. There is a challenge in Japan about the system.

The Central Symmetry Analysis of Wrinkle Ridges in Lunar Mare Serenitatis

NASA Astrophysics Data System (ADS)

Yao, Meijuan; Chen, Jianping

2018-03-01

Wrinkle ridges are one of the most common structures usually found in lunar mare basalts, and their formations are closely related to the lunar mare. In this paper, wrinkle ridges in Mare Serenitatis were identified and mapped via high-resolution data acquired from SELENE, and a quantitative method was introduced to analyze the degree of central symmetry of the wrinkle ridges distributed in a concentric or radial pattern. Meanwhile, two methods were used to measure the lengths and orientations of wrinkle ridges before calculating their central symmetry value. Based on the mapped wrinkle ridges, we calculated the central symmetry value of the wrinkle ridges for the whole Mare Serenitatis as well as for the four circular ridge systems proposed by a previous study via this method. We also analyzed the factors that would cause discrepancies when calculating the central symmetry value. The results indicate that the method can be used to quantitatively analyze the degree of central symmetry of the linear features that were concentrically or radially oriented and can reflect the stress field characteristics.

Content and chemical form of mercury and selenium in Lake Ontario salmon and trout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cappon, C.J.

1984-01-01

The content and chemical form of mercury and selenium were determined in the edible tissue of salmon (coho, chinook) and trout (lake, brown) taken offshore from Lake Ontario near Rochester, New York. For all species, total mercury content ranged from 0.3 to 0.8 micro g/g (fresh-weight), which is similar to concentrations commonly found in canned tuna. Most of the total mercury (63 to 79%) was present as methylmercury, the remainder being divalent inorganic mercury. For all species, 6 to 45% of the total selenium content was present as selenate (SeVI), the remainder being selenite (SeIV) and selenide (SEII). On amore » molar basis, total selenium content usually exceeded that of total mercury. Samples of smoked and unsmoked brown trout fillets were also examined. Based on the results of this study there is no immediate human health hazard from mercury and selenium. However, there is a need to report specific forms of these metals in Lake Ontario salmonid fish so that elevated concentrations can be better evaluated. 42 references, 1 figure, 4 tables.« less

Characterization and quantitation of phenolic compounds in new apricot (Prunus armeniaca L.) varieties.

PubMed

Ruiz, David; Egea, José; Gil, María I; Tomás-Barberán, Francisco A

2005-11-30

Thirty-seven apricot varieties, including four new releases (Rojo Pasión, Murciana, Selene, and Dorada) obtained from different crosses between apricot varieties and three traditional Spanish cultivars (Currot, Mauricio, and Búlida), were separated according to flesh color into four groups: white, yellow, light orange, and orange (mean hue angles in flesh were 88.1, 85.0, 77.6, and 72.4, respectively). Four phenolic compound groups, procyanidins, hydroxycinnamic acid derivatives, flavonols, and anthocyanins, were identified by HPLC-MS/MS and individually quantified using HPLC-DAD. Chlorogenic and neochlorogenic acids, procyanidins B1, B2, and B4, and some procyanidin trimers, quercetin 3-rutinoside, kaempferol 3-rhamnosyl-hexoside and quercetin 3-acetyl-hexoside, cyanidin 3-rutinoside, and 3-glucoside, were detected and quantified in the skin and flesh of the different cultivars. The total phenolics content, quantified as the addition of the individual compounds quantified by HPLC, ranged between 32.6 and 160.0 mg 100 g(-1) of edible tissue. No correlation between the flesh color and the phenolic content of the different cultivars was observed.

Influence of composition on the performance of sintered Cu(In,Ga)Se2 nanocrystal thin-film photovoltaic devices.

PubMed

Akhavan, Vahid A; Harvey, Taylor B; Stolle, C Jackson; Ostrowski, David P; Glaz, Micah S; Goodfellow, Brian W; Panthani, Matthew G; Reid, Dariya K; Vanden Bout, David A; Korgel, Brian A

2013-03-01

Thin-film photovoltaic devices (PVs) were prepared by selenization using oleylamine-capped Cu(In,Ga)Se2 (CIGS) nanocrystals sintered at a high temperature (>500 °C) under Se vapor. The device performance varied significantly with [Ga]/[In+Ga] content in the nanocrystals. The highest power conversion efficiency (PCE) observed in the devices studied was 5.1 % under air mass 1.5 global (AM 1.5 G) illumination, obtained with [Ga]/[In+Ga]=0.32. The variation in PCE with composition is partly a result of bandgap tuning and optimization, but the main influence of nanocrystal composition appeared to be on the quality of the sintered films. The [Cu]/[In+Ga] content was found to be strongly influenced by the [Ga]/[In+Ga] concentration, which appears to be correlated with the morphology of the sintered film. For this reason, only small changes in the [Ga]/[In+Ga] content resulted in significant variations in device efficiency. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Model of Relation between Fluctuation of Double Differential Total Ionospheric Electron Content and Angular Distance of the Two Satellites Observed by Same-beam VLBI

NASA Astrophysics Data System (ADS)

Xiao, Yao; Qing-hui, Liu

2018-01-01

Time delay and phase fluctuation are produced when the signals of a spacecraft are transmitted through the ionosphere of the earth, which give rise to a great influence on the measurement precision of VLBI (Very Long Baseline Interferometry). Using the 1-year same-beam VLBI data of 2 satellites (Rstar and Vstar) in the Japanese lunar exploration project SELENE, we obtained a model of the relation between the fluctuation of double differential total electron content in the ionosphere and the angular distance of the two satellites. For the 6 baselines, the root mean square r of fluctuation (in units of TECU) and the angular distance of the two satellites θ (in units of ∘) has a relation of r = 0.773θ + 0.562, and for the 4 VLBI stations, the relation is r = 0.554θ + 0.399 from the baselines inversion. The results can serve as a reference for the derivation of differential phase delay and for the occultation observation and study of planetary ionospheres.

Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: a review.

PubMed

Herrero Latorre, C; Barciela García, J; García Martín, S; Peña Crecente, R M

2013-12-04

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

The behavior of dissolved inorganic selenium in the Changjiang Estuary

NASA Astrophysics Data System (ADS)

Chang, Yan; Zhang, Jing; Qu, Jianguo; Zhang, Guosen; Zhang, Anyu; Zhang, Ruifeng

2016-02-01

To investigate the behavior of inorganic selenium species in the Changjiang Estuary, samples were taken during summer (July 2011) and winter (March 2012). Dissolved inorganic selenium (DISe) concentrations averaged 1.79 nmol/L in summer and 1.24 nmol/L in winter; the average selenite [Se(IV)] to selenate [Se(VI)] ratio [Se(IV)/Se(VI)] was 0.42 in summer and 0.61 in winter. The data show that Se(IV) and Se(VI) concentrations in the estuary behaved strictly conservatively during winter but non-conservatively during summer due to adsorption by suspended particulate matter (SPM) and assimilation by phytoplankton. In addition, the Se concentration distributions in the Changjiang Estuary were controlled by three water masses, each with a specific Se(IV)/Se(VI) ratio "signature": the Changjiang Water input, the Taiwan Warm Current, and the Yellow Sea Coastal Current. The Se(IV) concentrations were related to the nitrate, silicate, and phosphate concentrations in the estuary. The DISe and Se(IV) concentrations were comparable to those found in other coastal regions and estuaries, which were considered to be natural levels.

Lunar International Science Coordination/Calibration Targets

NASA Technical Reports Server (NTRS)

Head, J. W.; Issacson, P.; Petro, N.; Runyon, C.; Ohtake, M.; Foing, B.; Grande, M.

2007-01-01

A new era of international lunar exploration has begun and will expand over the next four years with data acquired from at least four sophisticated remote sensing missions: KAGUYA (SELENE) [Japan], Chang'E [China], Chandrayaan-l [India], and LRO [United States]. It is recognized that this combined activity at the Moon with modern sophisticated sensors wi II provide unprecedented new information about the Moon and will dramatically improve our understanding of Earth's nearest neighbor. It is anticipated that the blooming of scientific exploration of the Moon by nations involved in space activities will seed and foster peaceful international coordination and cooperation that will benefit all. Summarized here are eight Lunar International Science Coordination/Calibration Targets (L-ISCT) that are intended to a) allow cross-calibration of diverse multi-national instruments and b) provide a focus for training young scientists about a range of lunar science issues. The targets, discussed at several scientific forums, were selected for coordinated science and instrument calibration of orbital data. All instrument teams are encouraged to participate in a coordinated activity of early-release data that will improve calibration and validation of data across independent and diverse instruments.

[Selenium requirements of dairy goats].

PubMed

Dercksen, D P; Counotte, G H M; Hazebroek, M Klein; Arts, W; van Rijn, T

2007-06-15

Selenium is an essential part of the enzyme glutathione-peroxidase (GSH-Px) and plays an important role in the intracellular aspecific immune defence. Reference values for blood levels of GSH-Px are not available for dairy goats. The EU has authorized the addition of selenium (as E), in the form of sodium selenite or sodium selenate, to animal feeds, to a maximum of 0.5 mg selenium/kg complete feed. Dairy goats given feed containing the maximum level of selenium (0.5 mg/kg) had GSH-Px levels of more than 1000 U/g Hb. The reference values for GSH-Px in cattle, horses, and pigs are between 120 and 600 U/g Hb. Newborn kids had GSH-Px levels between 350 and 400 U/g Hb, comparable with those ofnewborn calves. In conclusion, the addition of selenium to feeds for dairy goats in amounts authorized by the EU leads to blood GSH-Px levels that are substantially higher than those in other species, such as horses, cattle, and pigs. Thus the maximum level of supplemental selenium in feeds for dairy goats should be less than 0.5 mg/kg.

Purification and characterization of a liver-derived beta-N-Acetylhexosaminidase from marine mammal Sotalia fluviatilis.

PubMed

Gomes Júnior, J E; Souza, D S L; Nascimento, R M; Lima, A L M; Melo, J A T; Rocha, T L; Miller, R N G; Franco, O L; Grossi-de-Sa, M F; Abreu, L R D

2010-04-01

A beta-N-Acetylhexosaminidase (EC 3.2.1.52) was purified from hepatic extracts of Sotalia fluviatilis, order Cetacea. The protein was purified by using ammonium sulfate fractionation and four subsequent chromatographies (Biogel A 1.5 m, Chitin, Deae-Biogel and hydroxyapatite resins). After these purification steps, the enzyme was purified 380.5-fold with an 8.4% yield. The molecular mass (10 kDa) was estimated by SDS-PAGE and MALDI-TOF analysis. A Km of 2.72 mM and Vmax 9.5 x 10(-6) micromol/(min x mg) were found for this enzyme, determined by p-nitrophenyl-beta-D: -hexosaminide substrate digestion. Optimal pH and temperature for beta-N-Acetylhexosaminidase activity were 5.0 and 60 degrees C, respectively. Enzyme activity was inhibited by sodium selenate (Na(2)SeO(4)), mercuric chloride (HgCl(2)) and sodium dodecyl sulfate (C(12)H(25)SO(4)Na), and activated by zinc, calcium, barium and lithium ions. Characterization of the beta-N-Acetylhexosaminidase in Sotalia fluviatilis can be a basis for physiological studies in this species.

Effects of Selenylation Modification on Immune-Enhancing Activity of Garlic Polysaccharide

PubMed Central

Qin, Tao; Hu, Yuanliang; Wang, Deyun; Fan, Qiang; Zhang, Cunshuai; Chen, Xingying; Chen, Xiaolan; Liu, Cui; Gao, Zhenzhen; Li, Xiuping

2014-01-01

The garlic polysaccharide was modified by HNO3-Na2SeO3 method according to orthogonal design L9(34) to obtain nine selenizing garlic polysaccharides, sGPS1-sGPS9. Their effects on chicken peripheral lymphocytes proliferation in vitro were compared by MTT assay. The results showed that sGPSs could significantly promote lymphocytes proliferation, sGPS3, sGPS5 and sGPS6 presented stronger efficacy. In vivo experiment, 14-day-old chickens were injected respectively with sGPS3, sGPS5 and sGPS6 when they were vaccinated with ND vaccine taking unmodified GPS as control. The results showed that three sGPSs could significantly promote lymphocyte proliferation, enhance serum antibody titer, IFN-γ and IL-2 contents. These results indicated that selenylation modification could significantly enhance the immune-enhancing activity of GPS, sGPS6 possessed the best efficacy and could be as a candidate drug of immunoenhancer. Its optimal modification conditions were 400 mg of sodium selenite for 500 mg of GPS, reaction temperature of 70°C and reaction time of 6 h. PMID:24497946

Effects of selenylation modification on immune-enhancing activity of garlic polysaccharide.

PubMed

Qiu, Shulei; Chen, Jin; Qin, Tao; Hu, Yuanliang; Wang, Deyun; Fan, Qiang; Zhang, Cunshuai; Chen, Xingying; Chen, Xiaolan; Liu, Cui; Gao, Zhenzhen; Li, Xiuping

2014-01-01

The garlic polysaccharide was modified by HNO3-Na2SeO3 method according to orthogonal design L9(3(4)) to obtain nine selenizing garlic polysaccharides, sGPS1-sGPS9. Their effects on chicken peripheral lymphocytes proliferation in vitro were compared by MTT assay. The results showed that sGPSs could significantly promote lymphocytes proliferation, sGPS3, sGPS5 and sGPS6 presented stronger efficacy. In vivo experiment, 14-day-old chickens were injected respectively with sGPS3, sGPS5 and sGPS6 when they were vaccinated with ND vaccine taking unmodified GPS as control. The results showed that three sGPSs could significantly promote lymphocyte proliferation, enhance serum antibody titer, IFN-γ and IL-2 contents. These results indicated that selenylation modification could significantly enhance the immune-enhancing activity of GPS, sGPS6 possessed the best efficacy and could be as a candidate drug of immunoenhancer. Its optimal modification conditions were 400 mg of sodium selenite for 500 mg of GPS, reaction temperature of 70°C and reaction time of 6 h.

Biogeographical affinities of fish associated to the shrimp trawl fishery in the Gulf of Tehuantepec, Mexico.

PubMed

Martínez-Muñoz, Marco A; Lloris, Domènec; Gracia, Adolfo; Ramírez-Murillo, Ricardo; Sarmiento-Nafáte, Saul; Ramos-Cruz, Sebastián; Fernández, Felipe

2016-06-01

Fish by-catch of shrimp fishery from the Gulf of Tehuantepec is composed of several species that are mainly discarded. In this study, fish by-catch species composition, distribution and biogeographical affinities were analyzed. For this, a total of 15 cruises were carried out on the continental shelf, at depths from 15 to 64 m, during 2003, 2004, 2005 and 2013. Results showed that fish by-catch was represented by 58 families, 129 genera and 242 species. The families Haemulidae, Sciaenidae, Paralichthyidae, Gerreidae and Carangidae accounted for > 70 % of the catch. Haemulopsis axillaris, Syacium ovale, Selene peruviana, Diapterus peruvianus, Larimus acclivins and Stellifer erycimba were the most frequent species at < 40 m depth (inner shelf), and Prionotus stephanophrys, Scorpaena russula, Porichthys analis and Synodus scituliceps were dominant at 40-60 m depth (outer shelf). Analysis of biogeographical affinities showed that 36.1 % of species had a wide distribution, from San Diego Province to the Panamic Province, while 13.2 % had a restricted distribution in the Mexican and Panamic Provinces. The ichthyofaunal composition was markedly influenced by the local environment and seasonal conditions.

Geomorphologic mapping of the lunar crater Tycho and its impact melt deposits

NASA Astrophysics Data System (ADS)

Krüger, T.; van der Bogert, C. H.; Hiesinger, H.

2016-07-01

Using SELENE/Kaguya Terrain Camera and Lunar Reconnaissance Orbiter Camera (LROC) data, we produced a new, high-resolution (10 m/pixel), geomorphological and impact melt distribution map for the lunar crater Tycho. The distal ejecta blanket and crater rays were investigated using LROC wide-angle camera (WAC) data (100 m/pixel), while the fine-scale morphologies of individual units were documented using high resolution (∼0.5 m/pixel) LROC narrow-angle camera (NAC) frames. In particular, Tycho shows a large coherent melt sheet on the crater floor, melt pools and flows along the terraced walls, and melt pools on the continuous ejecta blanket. The crater floor of Tycho exhibits three distinct units, distinguishable by their elevation and hummocky surface morphology. The distribution of impact melt pools and ejecta, as well as topographic asymmetries, support the formation of Tycho as an oblique impact from the W-SW. The asymmetric ejecta blanket, significantly reduced melt emplacement uprange, and the depressed uprange crater rim at Tycho suggest an impact angle of ∼25-45°.

Adsorption study of selenium ions from aqueous solutions using MgO nanosheets synthesized by ultrasonic method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Wenwen; Li, Ping; Wang, Zheming

tMgO nanosheets with thickness ranges of 3–10 molecule layers and high specific area (166.44 m2g-1)were successfully fabricated by an ultrasound-assisted exfoliation method and used as adsorbent forthe removal of both selenite (Se(IV)) and selenate (Se(VI)) from aqueous solutions. The resulting MgOnanosheets displayed high maximum adsorption capacities of 103.52 and 10.28 mg g-1for Se(IV) andSe(VI), respectively. ATR-FTIR and XPS spectroscopic results suggested that both Se(IV) and Se(VI) formedinner-sphere surface complexes on MgO nanosheets under the present experimental conditions. Fur-thermore, high adsorption capacity for Se(IV/VI) in the presence of coexistent anions (SO 4 2-, PO43-, Cl-,and F-) and efficient regeneratability of adsorbentmore » by NaOH solution were observed in the competitiveadsorption and regeneration steps. The simple one-step synthesis process of MgO nanosheets and highadsorption capacities offer a promising method for Se(IV/VI) removal in water treatment.« less

Improper ferroelectricity: A theoretical and experimental investigation

NASA Astrophysics Data System (ADS)

Hardy, J. R.; Ullman, F. G.

1984-02-01

A combined theoretical and experimental study has been made of the origins and properties of the improper ferroelectricity associated with structural modulations of non-zero wavelengths. Two classes of materials have been studied: rare earth molybdates (specifically, gadolinium molybdate: GMO), and potassium selenate and its isomorphs. In the former, the modulation is produced by a zone boundary phonon instability, and in the latter by the instability of a phonon of wave vector approximately two-thirds of the way to the zone-boundary. In the second case the initial result is a modulated structure whose repeat distance is not a rational multiple of the basic lattice repeat distance. This result is a modulated polarization which, when the basic modulation locks in to a rational multiple of the lattice spacing, becomes uniform, and improper ferroelectricity results. The origins of these effects have been elucidated by theoretical studies, initially semi-empirical, but subsequently from first-principles. These complemented the experimental work, which primarily used inelastic light scattering, uniaxial stress, and hydrostatic pressure, to probe the balance between the interionic forces through the effects on the phonons and dielectric properties.

Detection of betanodaviruses in apparently healthy aquarium fishes and invertebrates.

PubMed

Gomez, Dennis Kaw; Lim, Dong Joo; Baeck, Gun Wook; Youn, Hee Jeong; Shin, Nam Shik; Youn, Hwa Young; Hwang, Cheol Yong; Park, Jun Hong; Park, Se Chang

2006-12-01

Betanodaviruses are the causative agents of viral nervous necrosis (VNN) in cultured marine fish. A total of 237 apparently healthy aquarium fish, marine (65 species) and freshwater (12 species) fishes and marine invertebrates (4 species), which were stocked in a commercial aquarium in Seoul, South Korea, were collected from November 2005 to February 2006. The brains of the fish and other tissues of the invertebrates were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR to detect betanodavirus. Positive nested PCR results were obtained from the brains of 8 marine fish species (shrimp fish Aeoliscus strigatus, milkfish Chanos chanos, three spot damsel Dascyllus trimaculatus, Japanese anchovy Engraulis japonicus, pinecone fish Monocentris japonica, blue ribbon eel Rhinomuraena quaesita, look down fish Selene vomer, yellow tang Zebrasoma flavesenes), 1 marine invertebrate species (spiny lobster Pamulirus versicolor), and 2 freshwater fish species (South American leaf fish Monocirrhus polyacanthus and red piranha Pygocentrus nattereri). The detection rate in nested PCR was 11/237 (4.64%). These subclinically infected aquarium fish and invertebrates may constitute an inoculum source of betanodaviruses for cultured fishes in the Korean Peninsula.

Detection of betanodaviruses in apparently healthy aquarium fishes and invertebrates

PubMed Central

Gomez, Dennis Kaw; Lim, Dong Joo; Baeck, Gun Wook; Youn, Hee Jeong; Shin, Nam Shik; Youn, Hwa Young; Hwang, Cheol Yong; Park, Jun Hong

2006-01-01

Betanodaviruses are the causative agents of viral nervous necrosis (VNN) in cultured marine fish. A total of 237 apparently healthy aquarium fish, marine (65 species) and freshwater (12 species) fishes and marine invertebrates (4 species), which were stocked in a commercial aquarium in Seoul, South Korea, were collected from November 2005 to February 2006. The brains of the fish and other tissues of the invertebrates were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR to detect betanodavirus. Positive nested PCR results were obtained from the brains of 8 marine fish species (shrimp fish Aeoliscus strigatus, milkfish Chanos chanos, three spot damsel Dascyllus trimaculatus, Japanese anchovy Engraulis japonicus, pinecone fish Monocentris japonica, blue ribbon eel Rhinomuraena quaesita, look down fish Selene vomer, yellow tang Zebrasoma flavesenes), 1 marine invertebrate species (spiny lobster Pamulirus versicolor), and 2 freshwater fish species (South American leaf fish Monocirrhus polyacanthus and red piranha Pygocentrus nattereri). The detection rate in nested PCR was 11/237 (4.64%). These subclinically infected aquarium fish and invertebrates may constitute an inoculum source of betanodaviruses for cultured fishes in the Korean Peninsula. PMID:17106229

Improvement of the photovoltaic performance of Cu2ZnSn(S x Se1-x )4 solar cells by adding polymer in the precursor solution

NASA Astrophysics Data System (ADS)

Yang, Gang; Li, Yong-Feng; Yao, Bin; Ding, Zhan-Hui; Deng, Rui; Zhao, Hai-Feng; Zhang, Li-Gong; Zhang, Zhen-Zhong

2018-03-01

Kesterite Cu2ZnSn(S x Se1-x )4 (CZTSSe) thin films and related solar cells were successfully fabricated by a facile sol-gel method and selenization process. The influence of Polyvinylpyrrolidone (PVP) additive on the properties of the CZTSSe films and the power conversion efficiency (PCE) of the solar cells were investigated. The results reveal that the qualities of CZTSSe films can be manipulated by incorporating a small amount of PVP. With addition of 1 wt% of PVP, the smoothness and grain size of the CZTSSe films were greatly improved. The contact at the CZTSSe/Mo interface was also improved. As a result, the optimized PCE of solar cells improved from 2.24% to 4.34% after the addition of 1 wt% PVP due to the decrease of recombination at the interfaces. These results suggest that polymer addition in the precursor solution is a promising method for obtaining high quality of CZTSSe films and high-performance solar cells.

Cold adaptation of the mononuclear molybdoenzyme periplasmic nitrate reductase from the Antarctic bacterium Shewanella gelidimarina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, Philippa J.L.; Codd, Rachel, E-mail: rachel.codd@sydney.edu.au; School of Medical Sciences

2011-11-04

Highlights: Black-Right-Pointing-Pointer Cold-adapted phenotype of NapA from the Antarctic bacterium Shewanella gelidimarina. Black-Right-Pointing-Pointer Protein homology model of NapA from S. gelidimarina and mesophilic homologue. Black-Right-Pointing-Pointer Six amino acid residues identified as lead candidates governing NapA cold adaptation. Black-Right-Pointing-Pointer Molecular-level understanding of designing cool-temperature in situ oxyanion sensors. -- Abstract: The reduction of nitrate to nitrite is catalysed in bacteria by periplasmic nitrate reductase (Nap) which describes a system of variable protein subunits encoded by the nap operon. Nitrate reduction occurs in the NapA subunit, which contains a bis-molybdopterin guanine dinucleotide (Mo-MGD) cofactor and one [4Fe-4S] iron-sulfur cluster. The activity ofmore » periplasmic nitrate reductase (Nap) isolated as native protein from the cold-adapted (psychrophilic) Antarctic bacterium Shewanella gelidimarina (Nap{sub Sgel}) and middle-temperature adapted (mesophilic) Shewanella putrefaciens (Nap{sub Sput}) was examined at varied temperature. Irreversible deactivation of Nap{sub Sgel} and Nap{sub Sput} occurred at 54.5 and 65 Degree-Sign C, respectively. When Nap{sub Sgel} was preincubated at 21-70 Degree-Sign C for 30 min, the room-temperature nitrate reductase activity was maximal and invariant between 21 and 54 Degree-Sign C, which suggested that Nap{sub Sgel} was poised for optimal catalysis at modest temperatures and, unlike Nap{sub Sput}, did not benefit from thermally-induced refolding. At 20 Degree-Sign C, Nap{sub Sgel} reduced selenate at 16% of the rate of nitrate reduction. Nap{sub Sput} did not reduce selenate. Sequence alignment showed 46 amino acid residue substitutions in Nap{sub Sgel} that were conserved in NapA from mesophilic Shewanella, Rhodobacter and Escherichia species and could be associated with the Nap{sub Sgel} cold-adapted phenotype. Protein homology modeling of Nap{sub Sgel} using a mesophilic template with 66% amino acid identity showed the majority of substitutions occurred at the protein surface distal to the Mo-MGD cofactor. Two mesophilic {r_reversible} psychrophilic substitutions (Asn {r_reversible} His, Val {r_reversible} Trp) occurred in a region close to the surface of the NapA substrate funnel resulting in potential interdomain {pi}-{pi} and/or cation-{pi} interactions. Three mesophilic {r_reversible} psychrophilic substitutions occurred within 4.5 A of the Mo-MGD cofactor (Phe {r_reversible} Met, Ala {r_reversible} Ser, Ser {r_reversible} Thr) resulting in local regions that varied in hydrophobicity and hydrogen bonding networks. These results contribute to the understanding of thermal protein adaptation in a redox-active mononuclear molybdenum enzyme and have implications in optimizing the design of low-temperature environmental biosensors.« less

Seasonal Changes of Fish Assemblages in a Subtropical Lagoon in the SE Gulf of California

PubMed Central

Amezcua, F.; Amezcua-Linares, F.

2014-01-01

The composition and seasonal changes of the fish assemblage in a coastal lagoon system in southeastern Gulf of California were assessed from December 2001 to July 2005. A total of 20,877 organisms belonging to 191 species and 47 families were analyzed. We determined that almost all the species inhabiting the system were found; however some rare species were not captured in our study. The majority of the species found were demersal but in every season at least one pelagic or benthopelagic species showed high abundances. The moonfish, Selene peruviana, was the most abundant species, whilst the puffer, Sphoeroides annulatus, was the main species in terms of biomass. The species composition changed seasonally; results from the Simpson diversity index and the cumulative species curve show that seasonally almost all the species in the system for a given season were found. These changes were also reflected in the multivariate results. The seasonal variations could be attributed to the migration of species out of the system as they grow and the arrival of new ones, which could also be related to temperature patterns since this environmental factor changes considerably through the year. PMID:24672403

Synthesis and Characterization of an Earth-Abundant Cu2BaSn(S,Se)4 Chalcogenide for Photoelectrochemical Cell Application.

PubMed

Shin, Donghyeop; Ngaboyamahina, Edgard; Zhou, Yihao; Glass, Jeffrey T; Mitzi, David B

2016-11-17

Cu 2 BaSnS 4-x Se x films consisting of earth-abundant metals have been examined for photocathode application. Films with different Se contents (i.e., Cu 2 BaSnS 4-x Se x with x ≤ 2.4) were synthesized using a cosputter system with post-deposition sulfurization/selenization annealing treatments. Each film adopts a trigonal P3 1 crystal structure, with progressively larger lattice constants and with band gaps shifting from 2.0 to 1.6 eV, as more Se substitutes for S in the parent compound Cu 2 BaSnS 4 . Given the suitable bandgap and earth-abundant elements, the Cu 2 BaSnS 4-x Se x films were studied as prospective photocathodes for water splitting. Greater than 6 mA/cm 2 was obtained under illumination at -0.4 V versus reversible hydrogen electrode for Pt/Cu 2 BaSnS 4-x Se x films with ∼60% Se content (i.e., x = 2.4), whereas a bare Cu 2 BaSnS 4-x Se x (x = 2.4) film yielded ∼3 mA/cm 2 at -0.4 V/RHE.

Contribution of Sediment Compaction/Loading to the Ganges-Bangladesh Delta Subsidence

NASA Astrophysics Data System (ADS)

Karpytchev, Mikhail; Krien, Yann; Ballu, Valerie; Becker, Melanie; Calmant, Stephane; Spada, Giorgio; Guo, Junyi; Khan, Zahirul; Shum, Ck

2016-04-01

A pronounced spatial variability characterizes the subsidence/uplift rates in the Ganges-Bangladesh delta estimated from both sediment cores and modern geodetic techniques. The large variability of the subsidence rates suggests an interplay of different natural and anthropogenic processes including tectonics, sediment loading and sediment compaction, groundwater extaction among many others drivers of the delta vertical land movements.In this study, we focus on estimating the subsidence rates due to the sediments transported by the Ganges-Brahmaputra since the last 18 000 years. The delta subsidence induced by the sediment loading and the resulting sea level changes are modelled by the TABOO and SELEN software (Spada, 2003; Stocchi and Spada, 2007) in the framework of a gravitationally self-consistent Earth model. The loading history was obtained from available sediment cores and from the isopach map of Goodbread and Kuehl (2000). The results demonstrate that the delta loading enhanced by the Holocene sedimention can be responsable for a regular subsidence across the Ganges-Brahmaputra delta with an amplitude of 1-5 mm/yr along the Bengal coast. These estimates demonstrate that the contribution of the Holocene as well as modern sediment loading should be taken into account in climate change mitigation politicy for Bangladesh.

Seasonal changes of fish assemblages in a subtropical lagoon in the SE Gulf of California.

PubMed

Amezcua, F; Amezcua-Linares, F

2014-01-01

The composition and seasonal changes of the fish assemblage in a coastal lagoon system in southeastern Gulf of California were assessed from December 2001 to July 2005. A total of 20,877 organisms belonging to 191 species and 47 families were analyzed. We determined that almost all the species inhabiting the system were found; however some rare species were not captured in our study. The majority of the species found were demersal but in every season at least one pelagic or benthopelagic species showed high abundances. The moonfish, Selene peruviana, was the most abundant species, whilst the puffer, Sphoeroides annulatus, was the main species in terms of biomass. The species composition changed seasonally; results from the Simpson diversity index and the cumulative species curve show that seasonally almost all the species in the system for a given season were found. These changes were also reflected in the multivariate results. The seasonal variations could be attributed to the migration of species out of the system as they grow and the arrival of new ones, which could also be related to temperature patterns since this environmental factor changes considerably through the year.

Detailed Visualization of Phase Evolution during Rapid Formation of Cu(InGa)Se2 Photovoltaic Absorber from Mo/CuGa/In/Se Precursors.

PubMed

Koo, Jaseok; Kim, Sammi; Cheon, Taehoon; Kim, Soo-Hyun; Kim, Woo Kyoung

2018-03-02

Amongst several processes which have been developed for the production of reliable chalcopyrite Cu(InGa)Se 2 photovoltaic absorbers, the 2-step metallization-selenization process is widely accepted as being suitable for industrial-scale application. Here we visualize the detailed thermal behavior and reaction pathways of constituent elements during commercially attractive rapid thermal processing of glass/Mo/CuGa/In/Se precursors on the basis of the results of systematic characterization of samples obtained from a series of quenching experiments with set-temperatures between 25 and 550 °C. It was confirmed that the Se layer crystallized and then melted between 250 and 350 °C, completely disappearing at 500 °C. The formation of CuInSe 2 and Cu(InGa)Se 2 was initiated at around 450 °C and 550 °C, respectively. It is suggested that pre-heat treatment to control crystallization of Se layer should be designed at 250-350 °C and Cu(InGa)Se 2 formation from CuGa/In/Se precursors can be completed within a timeframe of 6 min.

Involvement of Superoxide Dismutases in the Response of Escherichia coli to Selenium Oxides

PubMed Central

Bébien, Magali; Lagniel, Gilles; Garin, Jérôme; Touati, Danièle; Verméglio, André; Labarre, Jean

2002-01-01

Selenium can provoke contrasting effects on living organisms. It is an essential trace element, and low concentrations have beneficial effects, such as the reduction of the incidence of cancer. However, higher concentrations of selenium salts can be toxic and mutagenic. The bases for both toxicity and protection are not clearly understood. To provide insights into these mechanisms, we analyzed the proteomic response of Escherichia coli cells to selenate and selenite treatment under aerobic conditions. We identified 23 proteins induced by both oxides and ca. 20 proteins specifically induced by each oxide. A striking result was the selenite induction of 8 enzymes with antioxidant properties, particularly the manganese and iron superoxide dismutases (SodA and SodB). The selenium inductions of sodA and sodB were controlled by the transcriptional regulators SoxRS and Fur, respectively. Strains with decreased superoxide dismutase activities were severely impaired in selenium oxide tolerance. Pretreatment with a sublethal selenite concentration triggered an adaptive response dependent upon SoxRS, conferring increased selenite tolerance. Altogether, our data indicate that superoxide dismutase activity is essential for the cellular defense against selenium salts, suggesting that superoxide production is a major mechanism of selenium toxicity under aerobic conditions. PMID:11872706

Monofluorophosphate is a selective inhibitor of respiratory sulfate-reducing microorganisms.

PubMed

Carlson, Hans K; Stoeva, Magdalena K; Justice, Nicholas B; Sczesnak, Andrew; Mullan, Mark R; Mosqueda, Lorraine A; Kuehl, Jennifer V; Deutschbauer, Adam M; Arkin, Adam P; Coates, John D

2015-03-17

Despite the environmental and economic cost of microbial sulfidogenesis in industrial operations, few compounds are known as selective inhibitors of respiratory sulfate reducing microorganisms (SRM), and no study has systematically and quantitatively evaluated the selectivity and potency of SRM inhibitors. Using general, high-throughput assays to quantitatively evaluate inhibitor potency and selectivity in a model sulfate-reducing microbial ecosystem as well as inhibitor specificity for the sulfate reduction pathway in a model SRM, we screened a panel of inorganic oxyanions. We identified several SRM selective inhibitors including selenate, selenite, tellurate, tellurite, nitrate, nitrite, perchlorate, chlorate, monofluorophosphate, vanadate, molydate, and tungstate. Monofluorophosphate (MFP) was not known previously as a selective SRM inhibitor, but has promising characteristics including low toxicity to eukaryotic organisms, high stability at circumneutral pH, utility as an abiotic corrosion inhibitor, and low cost. MFP remains a potent inhibitor of SRM growing by fermentation, and MFP is tolerated by nitrate and perchlorate reducing microorganisms. For SRM inhibition, MFP is synergistic with nitrite and chlorite, and could enhance the efficacy of nitrate or perchlorate treatments. Finally, MFP inhibition is multifaceted. Both inhibition of the central sulfate reduction pathway and release of cytoplasmic fluoride ion are implicated in the mechanism of MFP toxicity.

New insights into the Mo/Cu(In,Ga)Se2 interface in thin film solar cells: Formation and properties of the MoSe2 interfacial layer.

PubMed

Klinkert, T; Theys, B; Patriarche, G; Jubault, M; Donsanti, F; Guillemoles, J-F; Lincot, D

2016-10-21

Being at the origin of an ohmic contact, the MoSe 2 interfacial layer at the Mo/Cu(In,Ga)Se 2 interface in CIGS (Cu(In,Ga)Se 2 and related compounds) based solar cells has allowed for very high light-to-electricity conversion efficiencies up to 22.3%. This article gives new insights into the formation and the structural properties of this interfacial layer. Different selenization-steps of a Mo covered glass substrate prior to the CIGS deposition by co-evaporation led to MoSe 2 interfacial layers with varying thickness and orientation, as observed by x-ray diffraction and atomic resolution transmission electron microscopy. A novel model based on the anisotropy of the Se diffusion coefficient in MoSe 2 is proposed to explain the results. While the series resistance of finished CIGS solar cells is found to correlate with the MoSe 2 orientation, the adhesion forces between the CIGS absorber layer and the Mo substrate stay constant. Their counter-intuitive non-correlation with the configuration of the MoSe 2 interfacial layer is discussed and related to work from the literature.

Few-layer MoSe₂ possessing high catalytic activity towards iodide/tri-iodide redox shuttles.

PubMed

Lee, Lawrence Tien Lin; He, Jian; Wang, Baohua; Ma, Yaping; Wong, King Young; Li, Quan; Xiao, Xudong; Chen, Tao

2014-02-14

Due to the two-dimensional confinement of electrons, single- and few-layer MoSe₂ nanostructures exhibit unusual optical and electrical properties and have found wide applications in catalytic hydrogen evolution reaction, field effect transistor, electrochemical intercalation, and so on. Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I₃(-) to I(-) at the counter electrode. The few-layer MoSe₂ is fabricated by surface selenization of Mo-coated soda-lime glass. Our results show that the few-layer MoSe₂ displays high catalytic efficiency for the regeneration of I(-) species, which in turn yields a photovoltaic energy conversion efficiency of 9.00%, while the identical photoanode coupling with "champion" electrode based on Pt nanoparticles on FTO glass generates efficiency only 8.68%. Thus, a Pt- and FTO-free counter electrode outperforming the best conventional combination is obtained. In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance. Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost.

Structural investigation of MF, RF and DC sputtered Mo thin films for backside photovoltaic electrode

NASA Astrophysics Data System (ADS)

Małek, Anna K.; Marszałek, Konstanty W.; Rydosz, Artur M.

2016-12-01

Recently photovoltaics attracts much attention of research and industry. The multidirectional studies are carried out in order to improve solar cells performance, the innovative materials are still searched and existing materials and technology are optimized. In the multilayer structure of CIGS solar cells molybdenum (Mo) layer is used as a back contact. Mo layers meet all requirements for back side electrode: low resistivity, good adhesion to the substrate, high optical reflection in the visible range, columnar structure for Na ions diffusion, formation of an ohmic contact with the ptype CIGS absorber layer, and high stability during the corrosive selenization process. The high adhesion to the substrate and low resistivity in single Mo layer is difficult to be achieved because both properties depend on the deposition parameters, particularly on working gas pressure. Therefore Mo bilayers are applied as a back contact for CIGS solar cells. In this work the Mo layers were deposited by medium frequency sputtering at different process parameters. The effect of substrate temperature within the range of 50°C-200°C and working gas pressure from 0.7 mTorr to 7 mTorr on crystalline structure of Mo layers was studied.

Reduction of elemental selenium to selenide: Experiments with anoxic sediments and bacteria that respire Se-oxyanions

USGS Publications Warehouse

Herbel, M.J.; Blum, J.S.; Oremland, R.S.; Borglin, S.E.

2003-01-01

A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe-) when supplied with Se(O). B. selenitireducens was also able to reduce selenite [Se(IV)] through Se(O) to Se(-II). Reduction of Se(O) by B.selenitireducens was more rapid in cells grown on colloidal sulfur [S(O)] or Se(IV) as their electron acceptor than for cell lines grown on fumarate. In contrast, three cultures of selenate-respiring bacteria, Sulfurospirillum barnesii, B. arsenicoselenatis, and Selenihalanaerobacter shriftii either were unable to reduce Se(O) to Se(-II) or had only a very limited capacity to achieve this reduction. Biological reduction of Se(O) to Se(-II) was observed during incubation of estuarine sediment slurries, while no such activity was noted in formalin-killed controls. The majority of the Se(-II) produced was found in the sediments as a solid precipitate of FeSe, rather than in solution as HSe-. These results demonstrate that certain anaerobic bacteria have the capacity to reduce Se(O) to Se(-II), providing a possible biological explanation for the occurrence of the selenide species in some sedimentary rocks.

Cancer chemoprevention research with selenium in the post-SELECT era: Promises and challenges

PubMed Central

Lü, Junxuan; Zhang, Jinhui; Jiang, Cheng; Deng, Yibin; Özten, Nur; Bosland, Maarten C.

2016-01-01

The negative efficacy outcomes of double-blinded, randomized, placebo-controlled Phase III human clinical trials with selenomethionine (SeMet) and SeMet-rich selenized-yeast (Se-yeast) for prostate cancer prevention and Se-yeast for prevention of non-small cell lung cancer (NSCLC) in North America lead to rejection of SeMet/Se-yeast for cancer prevention in Se-adequate populations. We identify two major lessons from the outcomes of these trials: 1) The antioxidant hypothesis was tested in wrong subjects or patient populations. 2) The selection of Se agents was not supported by cell culture and preclinical animal efficacy data as is common in drug development. We propose that next-generation forms of Se (next-gen Se), such as methylselenol precursors, offer biologically appropriate approaches for cancer chemoprevention but these are faced with formidable challenges. Solid mechanism-based preclinical efficacy assessments and comprehensive safety studies with next-gen Se will be essential to re-vitalize the idea of cancer chemoprevention with Se in the post-SELECT era. We advocate smaller mechanism-driven Phase I/II trials with these next-gen Se to guide and justify future decisions for definitive Phase III chemoprevention efficacy trials. PMID:26595411

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

USGS Publications Warehouse

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.; Zawislanski, P.T.

1999-01-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are needed to confirm this preliminary assessment. We have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields ??0.2??? precision on 80Se/76Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 ??g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.

Cancer chemoprevention research with selenium in the post-SELECT era: Promises and challenges.

PubMed

Lü, Junxuan; Zhang, Jinhui; Jiang, Cheng; Deng, Yibin; Özten, Nur; Bosland, Maarten C

2016-01-01

The negative efficacy outcomes of double-blinded, randomized, placebo-controlled Phase III human clinical trials with selenomethionine (SeMet) and SeMet-rich selenized-yeast (Se-yeast) for prostate cancer prevention and Se-yeast for prevention of nonsmall cell lung cancer (NSCLC) in North America lead to rejection of SeMet/Se-yeast for cancer prevention in Se-adequate populations. We identify 2 major lessons from the outcomes of these trials: 1) the antioxidant hypothesis was tested in wrong subjects or patient populations, and 2) the selection of Se agents was not supported by cell culture and preclinical animal efficacy data as is common in drug development. We propose that next-generation forms of Se (next-gen Se), such as methylselenol precursors, offer biologically appropriate approaches for cancer chemoprevention but these are faced with formidable challenges. Solid mechanism-based preclinical efficacy assessments and comprehensive safety studies with next-gen Se will be essential to revitalize the idea of cancer chemoprevention with Se in the post-SELECT era. We advocate smaller mechanism-driven Phase I/II trials with these next-gen Se to guide and justify future decisions for definitive Phase III chemoprevention efficacy trials.

Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, T.M.; Herbel, M.J.; Bullen, T.D.

1999-09-01

Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. The authors report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are neededmore » to confirm this preliminary assessment. The authors have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields {+-}0.2% precision on {sup 80}Se/{sup 76}Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 {micro}g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.« less

Rescue of impaired late-phase long-term depression in a tau transgenic mouse model.

PubMed

Ahmed, Tariq; Blum, David; Burnouf, Sylvie; Demeyer, Dominique; Buée-Scherrer, Valérie; D'Hooge, Rudi; Buée, Luc; Balschun, Detlef

2015-02-01

Cognitive decline, the hallmark of Alzheimer's disease, and accompanying neuropsychiatric symptoms share dysfunctions of synaptic processes as a common cellular pathomechanism. Long-term potentiation has proven to be a sensitive tool for the "diagnosis" of such synaptic dysfunctions. Much less, however, is known about how long-term depression (LTD), an alternative mechanism for the storage of memory, is affected by Alzheimer's disease progression. Here, we demonstrate that impaired late LTD (>3 hours) in THY-Tau22 mice can be rescued by either inhibition of glycogen synthase kinase-3 (GSK3β) activity or by application of the protein-phosphatase 2A agonist selenate. In line with these findings, we observed increased phosphorylation of GSK3β at Y216 and reduced total phosphatase activity in biochemical assays of hippocampal tissue of THY-Tau22 mice. Interestingly, LTD induction and pharmacologic inhibition of GSK3β appeared to downregulate GSK3ß activity via a marked upregulation of phosphorylation at the inhibitory Ser9 residue. Our results point to alterations in phosphorylation and/or dephosphorylation homeostasis as key mechanisms underlying the deficits in LTD and hippocampus-dependent learning found in THY-Tau22 mice. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparative effect of Al, Se, and Mo toxicity on NO3(-) assimilation in sunflower (Helianthus annuus L.) plants.

PubMed

Ruiz, Juan M; Rivero, Rosa M; Romero, Luis

2007-04-01

Here, we study the effect caused by three trace elements--Al, Se, and Mo--applied at the same concentration (100 microM) and in their oxyanionic forms--NaAl(OH)(4), Na(2)SeO(4), and Na(2)MoO(4)--on NO(3)(-) assimilation (NO(3)(-), nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) activities, and concentrations of amino acids and proteins) in sunflower (Helianthus annuus L. var. Kasol) plants. The most harmful element for sunflower plants proved to be selenate, followed by aluminate. On the contrary, the application of molybdate had no negative effect on the growth of this plant, suggesting the possibility of using sunflower for the phytoremediation of this metal, mainly in agricultural zones used for grazing where the excess of this element can provoke problems of molybdenosis in ruminants (particularly in cattle). In addition, we found that the alteration of NO(3)(-) assimilation by SeO(4)(2-) and Al(OH)(4)(-) directly influences the growth and development of plants, foliar inhibition of NR activity by SeO(4)(2-) being more harmful than the decrease in foliar availability of NO(3)(-) provoked by Al(OH)(4)(-).

Steps Towards Industrialization of Cu–III–VI2Thin‐Film Solar Cells:Linking Materials/Device Designs to Process Design For Non‐stoichiometric Photovoltaic Materials

PubMed Central

Chang, Hsueh‐Hsin; Sharma, Poonam; Letha, Arya Jagadhamma; Shao, Lexi; Zhang, Yafei; Tseng, Bae‐Heng

2016-01-01

The concept of in‐line sputtering and selenization become industrial standard for Cu–III–VI2 solar cell fabrication, but still it's very difficult to control and predict the optical and electrical parameters, which are closely related to the chemical composition distribution of the thin film. The present review article addresses onto the material design, device design and process design using parameters closely related to the chemical compositions. Its variation leads to change in the Poisson equation, current equation, and continuity equation governing the device design. To make the device design much realistic and meaningful, we need to build a model that relates the opto‐electrical properties to the chemical composition. The material parameters as well as device structural parameters are loaded into the process simulation to give a complete set of process control parameters. The neutral defect concentrations of non‐stoichiometric CuMSe2 (M = In and Ga) have been calculated under the specific atomic chemical potential conditions using this methodology. The optical and electrical properties have also been investigated for the development of a full‐function analytical solar cell simulator. The future prospects regarding the development of copper–indium–gallium–selenide thin film solar cells have also been discussed. PMID:27840790

Tailoring Vacancies Far Beyond Intrinsic Levels Changes the Carrier Type and Optical Response in Monolayer MoSe 2-x Crystals

DOE PAGES

Mahjouri-Samani, Masoud; Liang, Liangbo; Oyedele, Akinola; ...

2016-01-01

Defect engineering has been a critical step in controlling the transport characteristics of electronic devices, and the ability to create, tune, and annihilate defects is essential to enable the range of next-generation devices. Whereas defect formation has been well-demonstrated in three-dimensional semiconductors, similar exploration of the heterogeneity in atomically thin two-dimensional semiconductors and the link between their atomic structures, defects, and properties has not yet been extensively studied. In this paper, we demonstrate the growth of MoSe 2–x single crystals with selenium (Se) vacancies far beyond intrinsic levels, up to ~20%, that exhibit a remarkable transition in electrical transport propertiesmore » from n- to p-type character with increasing Se vacancy concentration. A new defect-activated phonon band at ~250 cm -1 appears, and the A 1g Raman characteristic mode at 240 cm -1 softens toward ~230 cm -1 which serves as a fingerprint of vacancy concentration in the crystals. We show that post-selenization using pulsed laser evaporated Se atoms can repair Se-vacant sites to nearly recover the properties of the pristine crystals. Finally, first-principles calculations reveal the underlying mechanisms for the corresponding vacancy-induced electrical and optical transitions.« less

Characterization of microbial communities in subsurface nuclear blast cavities of the Nevada Test Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moser, Duane P; Czerwinski, Ken; Russell, Charles E

2010-07-13

This US Department of Energy (DOE) Environmental Remediation Sciences Project (ERSP) was designed to test fundamental hypotheses concerning the existence and nature of indigenous microbial populations of Nevada Test Site subsurface nuclear test/detonation cavities. Now called Subsurface Biogeochemical Research (SBR), this program's Exploratory Research (ER) element, which funded this research, is designed to support high risk, high potential reward projects. Here, five cavities (GASCON, CHANCELLOR, NASH, ALEMAN, and ALMENDRO) and one tunnel (U12N) were sampled using bailers or pumps. Molecular and cultivation-based techniques revealed bacterial signatures at five sites (CHANCELLOR may be lifeless). SSU rRNA gene libraries contained diverse andmore » divergent microbial sequences affiliated with known metal- and sulfur-cycling microorganisms, organic compound degraders, microorganisms from deep mines, and bacteria involved in selenate reduction and arsenite oxidation. Close relatives of Desulforudis audaxviator, a microorganism thought to subsist in the terrestrial deep subsurface on H2 and SO42- produced by radiochemical reactions, was detected in the tunnel waters. NTS-specific media formulations were used to culture and quantify nitrate-, sulfate-, iron-reducing, fermentative, and methanogenic microorganisms. Given that redox manipulations mediated by microorganisms can impact the mobility of DOE contaminants, our results should have implications for management strategies at this and other DOE sites.« less

Characterization of Microbial Communities in Subsurface Nuclear Blast Cavities of the Nevada Test Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moser, Duane P.; Bruckner, Jim; Fisher, Jen

2010-09-01

This U.S. Department of Energy (DOE) Environmental Remediation Sciences Project (ERSP) was designed to test fundamental hypotheses concerning the existence and nature of indigenous microbial populations of Nevada Test Site subsurface nuclear test/detonation cavities. Now called Subsurface Biogeochemical Research (SBR), this program’s Exploratory Research (ER) element, which funded this research, is designed to support high risk, high potential reward projects. Here, five cavities (GASCON, CHANCELLOR, NASH, ALEMAN, and ALMENDRO) and one tunnel (U12N) were sampled using bailers or pumps. Molecular and cultivation-based techniques revealed bacterial signatures at five sites (CHANCELLOR may be lifeless). SSU rRNA gene libraries contained diverse andmore » divergent microbial sequences affiliated with known metal- and sulfur-cycling microorganisms, organic compound degraders, microorganisms from deep mines, and bacteria involved in selenate reduction and arsenite oxidation. Close relatives of Desulforudis audaxviator, a microorganism thought to subsist in the terrestrial deep subsurface on H2 and SO42- produced by radiochemical reactions, was detected in the tunnel waters. NTS-specific media formulations were used to culture and quantify nitrate-, sulfate-, iron-reducing, fermentative, and methanogenic microorganisms. Given that redox manipulations mediated by microorganisms can impact the mobility of DOE contaminants, our results should have implications for management strategies at this and other DOE sites.« less

Comparison of Chemical Sensitivity of Fresh and Long-Stored Heat Resistant Neosartorya fischeri Environmental Isolates Using BIOLOG Phenotype MicroArray System

PubMed Central

Panek, Jacek; Frąc, Magdalena; Bilińska-Wielgus, Nina

2016-01-01

Spoilage of heat processed food and beverage by heat resistant fungi (HRF) is a major problem for food industry in many countries. Neosartorya fischeri is the leading source of spoilage in thermally processed products. Its resistance to heat processing and toxigenicity makes studies about Neosartorya fischeri metabolism and chemical sensitivity essential. In this study chemical sensitivity of two environmental Neosartorya fischeri isolates were compared. One was isolated from canned apples in 1923 (DSM3700), the other from thermal processed strawberry product in 2012 (KC179765), used as long-stored and fresh isolate, respectively. The study was conducted using Biolog Phenotype MicroArray platforms of chemical sensitivity panel and traditional hole-plate method. The study allowed for obtaining data about Neosartorya fischeri growth inhibitors. The fresh isolate appeared to be much more resistant to chemical agents than the long-stored isolate. Based on phenotype microarray assay nitrogen compounds, toxic cations and membrane function compounds were the most effective in growth inhibition of N. fischeri isolates. According to the study zaragozic acid A, thallium(I) acetate and sodium selenate were potent and promising N. fischeri oriented fungicides which was confirmed by both chemical sensitivity microplates panel and traditional hole-plate methods. PMID:26815302

Accumulation of heavy metals and trace elements in fluvial sediments received effluents from traditional and semiconductor industries

PubMed Central

Hsu, Liang-Ching; Huang, Ching-Yi; Chuang, Yen-Hsun; Chen, Ho-Wen; Chan, Ya-Ting; Teah, Heng Yi; Chen, Tsan-Yao; Chang, Chiung-Fen; Liu, Yu-Ting; Tzou, Yu-Min

2016-01-01

Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention. Moreover, we used Se XANES as an example to test the species transformation during metal transportation from effluent outlets to bed sediments and found a portion of Se inventory shifted from less soluble elemental Se to the high soluble and toxic selenite and selenate. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for bed sediments. PMID:27681994

Accumulation of heavy metals and trace elements in fluvial sediments received effluents from traditional and semiconductor industries.

PubMed

Hsu, Liang-Ching; Huang, Ching-Yi; Chuang, Yen-Hsun; Chen, Ho-Wen; Chan, Ya-Ting; Teah, Heng Yi; Chen, Tsan-Yao; Chang, Chiung-Fen; Liu, Yu-Ting; Tzou, Yu-Min

2016-09-29

Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention. Moreover, we used Se XANES as an example to test the species transformation during metal transportation from effluent outlets to bed sediments and found a portion of Se inventory shifted from less soluble elemental Se to the high soluble and toxic selenite and selenate. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for bed sediments.

Cancer incidence following long-term consumption of drinking water with high inorganic selenium content.

PubMed

Vinceti, Marco; Vicentini, Massimo; Wise, Lauren A; Sacchettini, Claudio; Malagoli, Carlotta; Ballotari, Paola; Filippini, Tommaso; Malavolti, Marcella; Rossi, Paolo Giorgi

2018-04-16

Selenium, a trace element to which humans are exposed mainly through diet, has been involved in the etiology of human cancer. We investigated the long-term effects of selenium exposure on cancer incidence using data from a natural experiment in Northern Italy. During the 1970s-1980s, in a part of the Italian municipality of Reggio Emilia, residents were inadvertently exposed to unusually high levels of inorganic hexavalent selenium (selenate) through drinking water. We followed the exposed residents for 28years, generating data on incidence (when available) and mortality rates for selected cancer sites; the remaining municipal residents comprised the unexposed (reference) group. We observed no substantial difference in overall cancer incidence comparing exposed and unexposed cohorts. We detected, however, a higher incidence of cancer at some sites, and for a few of them, namely cancers of the buccal cavity and pharynx, melanoma, urinary tract and lymphoid tissue, the excess incidence was particularly evident in the first period of follow-up but decreased over time. Overall, these results suggest that consumption of water with levels of selenium in its inorganic hexavalent form close to the European standard, 10μg/L, may have unfavourable effects on cancer incidence. Copyright © 2018 Elsevier B.V. All rights reserved.

Accumulation of heavy metals and trace elements in fluvial sediments received effluents from traditional and semiconductor industries

NASA Astrophysics Data System (ADS)

Hsu, Liang-Ching; Huang, Ching-Yi; Chuang, Yen-Hsun; Chen, Ho-Wen; Chan, Ya-Ting; Teah, Heng Yi; Chen, Tsan-Yao; Chang, Chiung-Fen; Liu, Yu-Ting; Tzou, Yu-Min

2016-09-01

Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention. Moreover, we used Se XANES as an example to test the species transformation during metal transportation from effluent outlets to bed sediments and found a portion of Se inventory shifted from less soluble elemental Se to the high soluble and toxic selenite and selenate. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for bed sediments.

Production of selenium nanoparticles in Pseudomonas putida KT2440.

PubMed

Avendaño, Roberto; Chaves, Nefertiti; Fuentes, Paola; Sánchez, Ethel; Jiménez, Jose I; Chavarría, Max

2016-11-15

Selenium (Se) is an essential element for the cell that has multiple applications in medicine and technology; microorganisms play an important role in Se transformations in the environment. Here we report the previously unidentified ability of the soil bacterium Pseudomonas putida KT2440 to synthesize nanoparticles of elemental selenium (nano-Se) from selenite. Our results show that P. putida is able to reduce selenite aerobically, but not selenate, to nano-Se. Kinetic analysis indicates that, in LB medium supplemented with selenite (1 mM), reduction to nano-Se occurs at a rate of 0.444 mmol L -1 h -1 beginning in the middle-exponential phase and with a final conversion yield of 89%. Measurements with a transmission electron microscope (TEM) show that nano-Se particles synthesized by P. putida have a size range of 100 to 500 nm and that they are located in the surrounding medium or bound to the cell membrane. Experiments involving dynamic light scattering (DLS) show that, in aqueous solution, recovered nano-Se particles have a size range of 70 to 360 nm. The rapid kinetics of conversion, easy retrieval of nano-Se and the metabolic versatility of P. putida offer the opportunity to use this model organism as a microbial factory for production of selenium nanoparticles.

Production of selenium nanoparticles in Pseudomonas putida KT2440

PubMed Central

Avendaño, Roberto; Chaves, Nefertiti; Fuentes, Paola; Sánchez, Ethel; Jiménez, Jose I.; Chavarría, Max

2016-01-01

Selenium (Se) is an essential element for the cell that has multiple applications in medicine and technology; microorganisms play an important role in Se transformations in the environment. Here we report the previously unidentified ability of the soil bacterium Pseudomonas putida KT2440 to synthesize nanoparticles of elemental selenium (nano-Se) from selenite. Our results show that P. putida is able to reduce selenite aerobically, but not selenate, to nano-Se. Kinetic analysis indicates that, in LB medium supplemented with selenite (1 mM), reduction to nano-Se occurs at a rate of 0.444 mmol L−1 h−1 beginning in the middle-exponential phase and with a final conversion yield of 89%. Measurements with a transmission electron microscope (TEM) show that nano-Se particles synthesized by P. putida have a size range of 100 to 500 nm and that they are located in the surrounding medium or bound to the cell membrane. Experiments involving dynamic light scattering (DLS) show that, in aqueous solution, recovered nano-Se particles have a size range of 70 to 360 nm. The rapid kinetics of conversion, easy retrieval of nano-Se and the metabolic versatility of P. putida offer the opportunity to use this model organism as a microbial factory for production of selenium nanoparticles. PMID:27845437

In situ diselenide-crosslinked polymeric micelles for ROS-mediated anticancer drug delivery.

PubMed

Deepagan, V G; Kwon, Seunglee; You, Dong Gil; Nguyen, Van Quy; Um, Wooram; Ko, Hyewon; Lee, Hansang; Jo, Dong-Gyu; Kang, Young Mo; Park, Jae Hyung

2016-10-01

Stimuli-responsive micelles have emerged as the drug carrier for cancer therapy since they can exclusively release the drug via their structural changes in response to the specific stimuli of the target site. Herein, we developed the in situ diselenide-crosslinked micelles (DCMs), which are responsive to the abnormal ROS levels of tumoral region, as anticancer drug carriers. The DCMs were spontaneously derived from selenol-bearing triblock copolymers consisting of polyethylene glycol (PEG) and polypeptide derivatives. During micelle formation, doxorubicine (DOX) was effectively encapsulated in the hydrophobic core, and diselenide crosslinks were formed in the shell. The DCMs maintained their structural integrity, at least for 6 days in physiological conditions, even in the presence of destabilizing agents. However, ROS-rich conditions triggered rapid release of DOX from the DOX-encapsulating DCMs (DOX-DCMs) because the hydrophobic diselenide bond was cleaved into hydrophilic selenic acid derivatives. Interestingly, after their systemic administration into the tumor-bearing mice, DOX-DCMs delivered significantly more drug to tumors (1.69-fold and 3.73-fold higher amount compared with their non-crosslinked counterparts and free drug, respectively) and effectively suppressed tumor growth. Overall, our data indicate that DCMs have great potential as drug carriers for anticancer therapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carotenoids from new apricot (Prunus armeniaca L.) varieties and their relationship with flesh and skin color.

PubMed

Ruiz, David; Egea, José; Tomás-Barberán, Francisco A; Gil, María I

2005-08-10

Thirty-seven apricot varieties, including four new releases (Rojo Pasión, Murciana, Selene, and Dorada) obtained from different crosses between apricot varieties and three traditional Spanish cultivars (Currot, Mauricio, and Búlida), were separated according to flesh color into four groups. The L*, a*, b*, hue angle, and chroma color measurements on the skin and flesh as well as other quality indices including flesh firmness, soluble solids, titratable acidity, and pH were plotted against the total carotenoid content measured by HPLC. Among the 37 apricot varieties, the total carotenoid content ranged from 1,512 to 16,500 microg 100 g(-1) of edible portion, with beta-carotene as the main pigment followed by beta-cryptoxanthin and gamma-carotene. The wide range of variability in the provitamin A content in the apricot varieties encouraged these studies in order to select the breeding types with enhanced carotenoid levels as the varieties with a higher potential health benefit. The carotenoid content was correlated with the color measurements, and the hue angle in both flesh and peel was the parameter with the best correlation (R = 0.92 and 0.84, respectively). An estimation of the carotenoid content in apricots could be achieved by using a portable colorimeter, as a simple and easy method for field usage applications.

Steps Towards Industrialization of Cu-III-VI2Thin-Film Solar Cells:Linking Materials/Device Designs to Process Design For Non-stoichiometric Photovoltaic Materials.

PubMed

Hwang, Huey-Liang; Chang, Hsueh-Hsin; Sharma, Poonam; Letha, Arya Jagadhamma; Shao, Lexi; Zhang, Yafei; Tseng, Bae-Heng

2016-10-01

The concept of in-line sputtering and selenization become industrial standard for Cu-III-VI 2 solar cell fabrication, but still it's very difficult to control and predict the optical and electrical parameters, which are closely related to the chemical composition distribution of the thin film. The present review article addresses onto the material design, device design and process design using parameters closely related to the chemical compositions. Its variation leads to change in the Poisson equation, current equation, and continuity equation governing the device design. To make the device design much realistic and meaningful, we need to build a model that relates the opto-electrical properties to the chemical composition. The material parameters as well as device structural parameters are loaded into the process simulation to give a complete set of process control parameters. The neutral defect concentrations of non-stoichiometric CuMSe 2 (M = In and Ga) have been calculated under the specific atomic chemical potential conditions using this methodology. The optical and electrical properties have also been investigated for the development of a full-function analytical solar cell simulator. The future prospects regarding the development of copper-indium-gallium-selenide thin film solar cells have also been discussed.

Controllable Growth of Ga Film Electrodeposited from Aqueous Solution and Cu(In,Ga)Se2 Solar Cells.

PubMed

Bi, Jinlian; Ao, Jianping; Gao, Qing; Zhang, Zhaojing; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Zhang, Yi

2017-06-07

Electrodepositon of Ga film is very challenging due to the high standard reduction potential (-0.53 V vs SHE for Ga 3+ ). In this study, Ga film with compact structure was successfully deposited on the Mo/Cu/In substrate by the pulse current electrodeposition (PCE) method using GaCl 3 aqueous solution. A high deposition rate of Ga 3+ and H + can be achieved by applying a large overpotential induced by high pulse current. In the meanwhile, the concentration polarization induced by cation depletion can be minimized by changing the pulse frequency and duty cycle. Uniform and smooth Ga film was fabricated at high deposition rate with pulse current density 125 mA/cm 2 , pulse frequency 5 Hz, and duty cycle 0.25. Ga film was then selenized together with electrodeposited Cu and In films to make a CIGSe absorber film for solar cells. The solar cell based on the Ga film presents conversion efficiency of 11.04%, fill factor of 63.40%, and V oc of 505 mV, which is much better than those based on the inhomogeneous and rough Ga film prepared by the DCE method, indicating the pulse current electrodeposition process is promising for the fabrication of CIGSe solar cell.

Improved performance of low cost CuInS2 superstrate-type solar cells using Zinc assisted spray pyrolysis processing

NASA Astrophysics Data System (ADS)

Cheshme Khavar, Amir Hossein; Mahjoub, Ali Reza; Taghavinia, Nima

2017-12-01

Superstrate configuration CuInS2 (CIS) solar cells are fabricated using a spray pyrolysis method. We avoided selenization process, cyanide etching and CdS buffer layer, to keep the process ‘green’. CIS layers are formed by spray pyrolysis of an aqueous precursor ink containing metal chloride salts and thiourea at 350 °C. We investigated the effect of intentional Zn doping on structural, morphological and photovoltaic response of the fabricated CIS films by dissolving ZnCl2 in aqueous precursor solution. At a zinc doping level ranging between 0.25 and 1.00 mol%, Zn doping is found to improve the CIS crystal growth and surface morphology of CIS films. Compared with the performance of the non-doped CIS cell, the Zn-doped CIS solar cell displayed a remarkable efficiency enhancement of 58-97% and the maximum enhancement was obtained at a Zn content of 0.5 mol%. The device structure consists of    and show promising PCE of 4.29 % without any anti-reflection coating. Over the course of 300 d under ambient condition, the fabricated device showed only 1% loss in efficiency.

Selenizing Hericium erinaceus polysaccharides induces dendritic cells maturation through MAPK and NF-κB signaling pathways.

PubMed

Qin, Tao; Ren, Zhe; Huang, Yifan; Song, Yulong; Lin, Dandan; Li, Jian; Ma, Yufang; Wu, Xiuqin; Qiu, Fuan; Xiao, Qi

2017-04-01

In this study, polysaccharides extracted from Hericium erinaceus were modified to obtain its nine selenium derivatives, sHEP 1 -sHEP 9 . Their structures were identified, yields and selenium contents were determined, the phenotypic and functional maturation of murine bone marrow-derived dendritic cells (DCs) and relevant mechanisms were compared taking unmodified HEP as control. The results revealed that the selenylation were successful. sHEP 1 , sHEP 2 and sHEP 8 treatment of DCs increased their surface expression of MHC-II and CD86 and indicated that sHEP 1 , sHEP 2 and sHEP 8 induced DC maturation. Furthermore, sHEP 2 and sHEP 8 also significantly decreased DCs endocytosis and significantly enhanced cytokine (IL-12 and IFN-γ) production. In line with TLR4 activation, sHEP 2 increased the phosphorylation of ERK, p38, and JNK, and the nuclear translocation of p-c-Jun, p-CREB, and c-Fos. sHEP 2 also activated NF-κB signaling, as evidenced by degradation of IκBα/β and nuclear translocation of p65 and p50. Together, these results suggest that sHEP is a strong immunostimulant. Copyright © 2017 Elsevier B.V. All rights reserved.

Selenium content in sulfide ores from the Chalkidiki peninsula, Greece.

PubMed

Nicolaidou, A E

1998-01-01

Selenium (Se) was assessed in galena, sphalerite, and pyrite samples. These are components of mixed sulfide ores from the Olympias and Madem Lakkos-Mavres Petres deposits and the Skouries porphyry-copper deposit. We used atomic absorption spectroscopy (AAS) with a hydride generator system. The highest concentration of Se (516 ppm) was found in the fine-grained galena at the -135 level of the Olympias deposits. In the Madem Lakkos-Mavres Petres deposit, the highest concentration of Se (33 ppm) was found in the pyrites of the level 30. The concentration of Se in the arsenopyrites and chalcopyrites is lower than the detection limit of the analytical method (< 100 ppb). The concentrated chalcopyrite from the porphyry copper deposit at Skouries exhibits a significant Se content (average 200 ppm) in contrast to the chalcopyrite from the Olympias and the Madem Lakkos-Mavres Petres. Variations in the Se content of the sulfide minerals studied could be caused by redox-pH and/or temperature conditions, as well as by the difference in crystal structure. The Se found in the areas studied may positively affect the environment. Sulfide minerals are oxidized by microorganisms, infiltrate in the soil-water in the form of selenate or selenite ion, and directly or indirectly influence the human organism.

One Moon, many measurements 1: Radiance values

NASA Astrophysics Data System (ADS)

Pieters, C. M.; Boardman, J. W.; Ohtake, M.; Matsunaga, T.; Haruyama, J.; Green, R. O.; Mall, U.; Staid, M. I.; Isaacson, P. J.; Yokota, Y.; Yamamoto, S.; Besse, S.; Sunshine, J. M.

2013-09-01

Several modern optical instruments orbited the Moon during 2008 and 2009 onboard the SELENE and Chandrayaan-1 spacecraft and provided a welcomed feast of spectroscopic data to be used for scientific analyses. The different spatial and spectral resolutions of these sensors along with diverse illumination geometry during data acquisition make each set of data unique, and each instrument contributes special value to integrated science analyses. In order to provide the maximum science benefit, we have undertaken a careful cross-validation of radiance data among these orbital instruments and also a set of systematic data acquired using Earth-based telescopes. Most radiance values at 750 nm fall between 0 and 100 W/(m2 μm sr), but a small important fraction can be up to ×2 to ×3 that value, with the largest values occurring at the highest spatial resolution. All instruments are in agreement about overall spectral properties of lunar materials, but small systematic differences are documented between instruments. Lunar radiance values measured with remote sensors for landing sites are all not as high as that estimated from laboratory measurements of returned soil. This is largely because laboratory measurements of lunar soils cannot retain or duplicate the fine structure of lunar regolith found in the natural space environment.

Compositional evidence for an impact origin of the Moon's Procellarum basin

NASA Astrophysics Data System (ADS)

Nakamura, Ryosuke; Yamamoto, Satoru; Matsunaga, Tsuneo; Ishihara, Yoshiaki; Morota, Tomokatsu; Hiroi, Takahiro; Takeda, Hiroshi; Ogawa, Yoshiko; Yokota, Yasuhiro; Hirata, Naru; Ohtake, Makiko; Saiki, Kazuto

2012-11-01

The asymmetry between the nearside and farside of the Moon is evident in the distribution of mare basalt, crustal thickness and concentrations of radioactive elements, but its origin remains controversial. According to one attractive scenario, a gigantic impact early in the Moon's history produced the observed dichotomy; the putative 3,000-km-diameter Procellarum basin has been suggested to be a relic of this ancient impact. Low-calcium pyroxene can be formed during an impact by melting a mixture of crust and mantle materials or by excavating differentiated cumulates from the lunar magma ocean. Therefore, the association of low-calcium pyroxene with a lunar basin could indicate an impact origin. Here we use spectral mapping data from KAGUYA/SELENE (ref. ) to show that low-calcium pyroxene is concentrated around two established impact structures, the South Pole-Aitken and Imbrium basins. In addition, we detect a high concentration of low-calcium pyroxene at Procellarum, which supports an impact origin of the ancient basin. We propose that, in forming the largest known basin on the Moon, the impact excavated the nearside's primary feldspathic crust, which derived from the lunar magma ocean. A secondary feldspathic crust would have later recrystallized from the sea of impact melt, leading to two distinct sides of the Moon.

Sequential extractions of selenium soils from Stewart Lake: total selenium and speciation measurements with ICP-MS detection.

PubMed

Ponce de León, Claudia A; DeNicola, Katie; Montes Bayón, Maria; Caruso, Joseph A

2003-06-01

Different techniques have been employed in order to evaluate the most efficient procedure for the extraction of selenium from soil as required for speciation. Selenium contaminated sediments from Stewart Lake Wetland, California were used. A strong acid mineralization of the samples gives quantitative total selenium, which is then used to estimate recoveries for the milder extraction methods. The different extraction methodologies involve the sequential use of water, buffer (phosphate, pH 7) and either acid solution (e.g. HNO3 or HCl) or basic solutions (e.g. ammonium acetate, NaOH or TMAH). Pyrophosphate extraction was also evaluated and showed that selenium was not associated with humic acids. The extractants were subsequently analyzed by size exclusion chromatography (SEC) with UV (254 and 400 nm) and on-line ICP-MS detection; anion exchange chromatography, and ion-pair reversed phase chromatography with ICP-MS detection. For sequential extractions the extraction efficiencies showed that the basic extractions were more efficient than the acidic. The difference between the acidic and the basic extraction efficiency is carried to the sulfite extraction, suggesting that whatever is not extracted by the acid is subsequently extracted by the sulfite. The species identified with the different chromatographies were selenate, selenite, elemental selenium and some organic selenium.

Rhizosphere Bacteria Enhance Selenium Accumulation and Volatilization by Indian Mustard1

PubMed Central

de Souza, Mark P.; Chu, Dara; Zhao, May; Zayed, Adel M.; Ruzin, Steven E.; Schichnes, Denise; Terry, Norman

1999-01-01

Indian mustard (Brassica juncea L.) accumulates high tissue Se concentrations and volatilizes Se in relatively nontoxic forms, such as dimethylselenide. This study showed that the presence of bacteria in the rhizosphere of Indian mustard was necessary to achieve the best rates of plant Se accumulation and volatilization of selenate. Experiments with the antibiotic ampicillin showed that bacteria facilitated 35% of plant Se volatilization and 70% of plant tissue accumulation. These results were confirmed by inoculating axenic plants with rhizosphere bacteria. Compared with axenic controls, plants inoculated with rhizosphere bacteria had 5-fold higher Se concentrations in roots (the site of volatilization) and 4-fold higher rates of Se volatilization. Plants with bacteria contained a heat-labile compound in their root exudate; when this compound was added to the rhizosphere of axenic plants, Se accumulation in plant tissues increased. Plants with bacteria had an increased root surface area compared with axenic plants; the increased area was unlikely to have caused their increased tissue Se accumulation because they did not accumulate more Se when supplied with selenite or selenomethionine. Rhizosphere bacteria also possibly increased plant Se volatilization because they enabled plants to overcome a rate-limiting step in the Se volatilization pathway, i.e. Se accumulation in plant tissues. PMID:9952452

Towards environmentally benign approaches for the synthesis of CZTSSe nanocrystals by a hot injection method: a status review.

PubMed

Ghorpade, Uma; Suryawanshi, Mahesh; Shin, Seung Wook; Gurav, Kishor; Patil, Pramod; Pawar, Sambhaji; Hong, Chang Woo; Kim, Jin Hyeok; Kolekar, Sanjay

2014-10-07

With the earth's abundance of kesterite, recent progress in chalcogenide based Cu2ZnSn(Sx,Se1-x)4 (CZTSSe) thin films has drawn prime attention in thin film solar cells (TFSCs) research and development. This review is focused on the current developments in the synthesis of CZTS nanocrystals (NCs) using a hot injection (HI) technique and provides comprehensive discussions on the current status of CZTSSe TFSCs. This article begins with a description of the advantages of nanoparticulate based thin films, and then introduces the basics of this technique and the corresponding growth mechanism is also discussed. A brief overview further addresses a series of investigations on the developments in the HI based CZTSSe NCs using different solvents in terms of their high toxicity to environmentally benign materials. A variety of recipes and techniques for the NCs ink formulation and thereby the preparation of absorber layers using NC inks are outlined, respectively. The deposition of precursor thin films, post-deposition processes such as sulfurization or selenization treatments and the fabrication of CZTSSe NCs based solar cells and their performances are discussed. Finally, we discussed concluding remarks and the perspectives for further developments in the existing research on CZTSSe based nanoparticulate (NP) TFSCs towards future green technology.

Purification and Characterization of (Per)Chlorate Reductase from the Chlorate-Respiring Strain GR-1

PubMed Central

Kengen, Servé W. M.; Rikken, Geoffrey B.; Hagen, Wilfred R.; van Ginkel, Cees G.; Stams, Alfons J. M.

1999-01-01

Strain GR-1 is one of several recently isolated bacterial species that are able to respire by using chlorate or perchlorate as the terminal electron acceptor. The organism performs a complete reduction of chlorate or perchlorate to chloride and oxygen, with the intermediate formation of chlorite. This study describes the purification and characterization of the key enzyme of the reductive pathway, the chlorate and perchlorate reductase. A single enzyme was found to catalyze both the chlorate- and perchlorate-reducing activity. The oxygen-sensitive enzyme was located in the periplasm and had an apparent molecular mass of 420 kDa, with subunits of 95 and 40 kDa in an α3β3 composition. Metal analysis showed the presence of 11 mol of iron, 1 mol of molybdenum, and 1 mol of selenium per mol of heterodimer. In accordance, quantitative electron paramagnetic resonance spectroscopy showed the presence of one [3Fe-4S] cluster and two [4Fe-4S] clusters. Furthermore, two different signals were ascribed to Mo(V). The Kmvalues for perchlorate and chlorate were 27 and <5 μM, respectively. Besides perchlorate and chlorate, nitrate, iodate, and bromate were also reduced at considerable rates. The resemblance of the enzyme to nitrate reductases, formate dehydrogenases, and selenate reductase is discussed. PMID:10542172

Few-Layer MoSe2 Possessing High Catalytic Activity towards Iodide/Tri-iodide Redox Shuttles

PubMed Central

Lee, Lawrence Tien Lin; He, Jian; Wang, Baohua; Ma, Yaping; Wong, King Young; Li, Quan; Xiao, Xudong; Chen, Tao

2014-01-01

Due to the two-dimensional confinement of electrons, single- and few-layer MoSe2 nanostructures exhibit unusual optical and electrical properties and have found wide applications in catalytic hydrogen evolution reaction, field effect transistor, electrochemical intercalation, and so on. Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I3− to I− at the counter electrode. The few-layer MoSe2 is fabricated by surface selenization of Mo-coated soda-lime glass. Our results show that the few-layer MoSe2 displays high catalytic efficiency for the regeneration of I− species, which in turn yields a photovoltaic energy conversion efficiency of 9.00%, while the identical photoanode coupling with “champion” electrode based on Pt nanoparticles on FTO glass generates efficiency only 8.68%. Thus, a Pt- and FTO-free counter electrode outperforming the best conventional combination is obtained. In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance. Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost. PMID:24525919

Yeast as a model system to study metabolic impact of selenium compounds

PubMed Central

Herrero, Enrique; Wellinger, Ralf E.

2015-01-01

Inorganic Se forms such as selenate or selenite (the two more abundant forms in nature) can be toxic in Saccharomyces cerevisiae cells, which constitute an adequate model to study such toxicity at the molecular level and the functions participating in protection against Se compounds. Those Se forms enter the yeast cell through other oxyanion transporters. Once inside the cell, inorganic Se forms may be converted into selenide through a reductive pathway that in physiological conditions involves reduced glutathione with its consequent oxidation into diglutathione and alteration of the cellular redox buffering capacity. Selenide can subsequently be converted by molecular oxygen into elemental Se, with production of superoxide anions and other reactive oxygen species. Overall, these events result in DNA damage and dose-dependent reversible or irreversible protein oxidation, although additional oxidation of other cellular macromolecules cannot be discarded. Stress-adaptation pathways are essential for efficient Se detoxification, while activation of DNA damage checkpoint and repair pathways protects against Se-mediated genotoxicity. We propose that yeast may be used to improve our knowledge on the impact of Se on metal homeostasis, the identification of Se-targets at the DNA and protein levels, and to gain more insights into the mechanism of Se-mediated apoptosis. PMID:28357286

Proceedings of the 39th Lunar and Planetary Science Conference

NASA Technical Reports Server (NTRS)

2008-01-01

Sessions with oral presentations include: A SPECIAL SESSION: MESSENGER at Mercury, Mars: Pingos, Polygons, and Other Puzzles, Solar Wind and Genesis: Measurements and Interpretation, Asteroids, Comets, and Small Bodies, Mars: Ice On the Ground and In the Ground, SPECIAL SESSION: Results from Kaguya (SELENE) Mission to the Moon, Outer Planet Satellites: Not Titan, Not Enceladus, SPECIAL SESSION: Lunar Science: Past, Present, and Future, Mars: North Pole, South Pole - Structure and Evolution, Refractory Inclusions, Impact Events: Modeling, Experiments, and Observations, Mars Sedimentary Processes from Victoria Crater to the Columbia Hills, Formation and Alteration of Carbonaceous Chondrites, New Achondrite GRA 06128/GRA 06129 - Origins Unknown, The Science Behind Lunar Missions, Mars Volcanics and Tectonics, From Dust to Planets (Planetary Formation and Planetesimals):When, Where, and Kaboom! Astrobiology: Biosignatures, Impacts, Habitability, Excavating a Comet, Mars Interior Dynamics to Exterior Impacts, Achondrites, Lunar Remote Sensing, Mars Aeolian Processes and Gully Formation Mechanisms, Solar Nebula Shake and Bake: Mixing and Isotopes, Lunar Geophysics, Meteorites from Mars: Shergottite and Nakhlite Invasion, Mars Fluvial Geomorphology, Chondrules and Chondrule Formation, Lunar Samples: Chronology, Geochemistry, and Petrology, Enceladus, Venus: Resurfacing and Topography (with Pancakes!), Overview of the Lunar Reconnaissance Orbiter Mission, Mars Sulfates, Phyllosilicates, and Their Aqueous Sources, Ordinary and Enstatite Chondrites, Impact Calibration and Effects, Comparative Planetology, Analogs: Environments and Materials, Mars: The Orbital View of Sediments and Aqueous Mineralogy, Planetary Differentiation, Titan, Presolar Grains: Still More Isotopes Out of This World, Poster sessions include: Education and Public Outreach Programs, Early Solar System and Planet Formation, Solar Wind and Genesis, Asteroids, Comets, and Small Bodies, Carbonaceous Chondrites, Chondrules and Chondrule Formation, Chondrites, Refractory Inclusions, Organics in Chondrites, Meteorites: Techniques, Experiments, and Physical Properties, MESSENGER and Mercury, Lunar Science Present: Kaguya (SELENE) Results, Lunar Remote Sensing: Basins and Mapping of Geology and Geochemistry, Lunar Science: Dust and Ice, Lunar Science: Missions and Planning, Mars: Layered, Icy, and Polygonal, Mars Stratigraphy and Sedimentology, Mars (Peri)Glacial, Mars Polar (and Vast), Mars, You are Here: Landing Sites and Imagery, Mars Volcanics and Magmas, Mars Atmosphere, Impact Events: Modeling, Experiments, and Observation, Ice is Nice: Mostly Outer Planet Satellites, Galilean Satellites, The Big Giant Planets, Astrobiology, In Situ Instrumentation, Rocket Scientist's Toolbox: Mission Science and Operations, Spacecraft Missions, Presolar Grains, Micrometeorites, Condensation-Evaporation: Stardust Ties, Comet Dust, Comparative Planetology, Planetary Differentiation, Lunar Meteorites, Nonchondritic Meteorites, Martian Meteorites, Apollo Samples and Lunar Interior, Lunar Geophysics, Lunar Science: Geophysics, Surface Science, and Extralunar Components, Mars, Remotely, Mars Orbital Data - Methods and Interpretation, Mars Tectonics and Dynamics, Mars Craters: Tiny to Humongous, Mars Sedimentary Mineralogy, Martian Gullies and Slope Streaks, Mars Fluvial Geomorphology, Mars Aeolian Processes, Mars Data and Mission,s Venus Mapping, Modeling, and Data Analysis, Titan, Icy Dwarf Satellites, Rocket Scientist's Toolbox: In Situ Analysis, Remote Sensing Approaches, Advances, and Applications, Analogs: Sulfates - Earth and Lab to Mars, Analogs: Remote Sensing and Spectroscopy, Analogs: Methods and Instruments, Analogs: Weird Places!. Print Only Early Solar System, Solar Wind, IDPs, Presolar/Solar Grains, Stardust, Comets, Asteroids, and Phobos, Venus, Mercury, Moon, Meteorites, Mars, Astrobiology, Impacts, Outer Planets, Satellites, and Rings, Support for Mission Operations, Analog Education and Public Outreach.

The Red de Monitoreo de BosquesAndinos: A communication platform for science and policy in the Andean countries

NASA Astrophysics Data System (ADS)

Baez, S.; Cuesta, F. X.; Malizia, A.; Carilla, J.; Bustamante, M.; Yepes, A.

2013-05-01

A workshop held in October 2012 in Lima, Peru, brought together more than 40 scientists and policy makers working in Andean forest ecosystems, one of the richer and most threatened ecosystems of the world. Among the various results of the workshop, there is the formation of the network "Red de Bosques Andinos". The goals of the network include to stimulate scientific research in Andean forest ecosystems by promoting collaboration among scientists, and to serve as a platform to facilitate applied research and communication between scientists and policy makers. Current members of the network include scientists of Argentina, Colombia, Ecuador, Germany, Peru, USA, and representatives of Ministries of Environment and the National Climate Change Adaptation Programs of Colombia, Bolivia, Ecuador, and Peru. The network has started to work in two critical documents for the region. The first one is an extended protocol to monitor diversity and carbon in Andean forests. This protocol, partly based on unpublished efforts, has been developed by the Instituto de Ecología Regional, Universidad de Tucuman, Argentina, and has been revised and improved by experts working in the Andes. The document describe methods to document ecological changes that take place over mid- and long periods of time. It focuses on monitoring changes on the diversity and growth of trees, shrubs and lianas, cover of herbaceous species, and carbon content in forests. This extended protocol will be a useful tool for students and researchers interested in conducting long-term ecological research. Moreover, the use of this tool will produce standardized data needed to understand ecological processes that take place at large spatial scales. The document will be freely available at www.condesan.org. The second document consists of an analysis of the dynamics of trees and carbon in the Andean region. The members of the network have contributed with data of more than 70 permanent forest plots located from Colombia to Argentina, some of them monitored since 1990. The initial results indicate that warmer, wetter, and more seasonal forests had higher rates of turnover of individuals, and biomass. Most of these patterns held for both, tropical and subtropical forest plots. The study will be completed in 2013, and will be the first study of forest dynamics and carbon content for the countries in the region. Finally, it is the aim of the Andean Forest Network to bring together scientists and policy-makers interested in research, management and conservation of the Andean forest. The creation of the network and the development of its first two products have been possible thanks to the financial support of the Swiss Agency of International Cooperation (COSUDE) through the CIMA project, the Dutch Technical Agency (GIZ), and the endorsement of the Secretaría General de Naciones (SG-CAN). The coordination of the network is currently held by Selene Báez, at CONDESAN (selene.baez@condesan.org). Please contact us if you need more information or if you are interested in becoming part of the network.

Short-term microbial effects of a large-scale mine-tailing storage facility collapse on the local natural environment

PubMed Central

Baldwin, Susan A.; Taylor, Jon; Gurr, David B.; Denesiuk, Daniel R.; Van Hamme, Jonathan D.; Fraser, Lauchlan H.

2018-01-01

We investigated the impacts of the Mount Polley tailings impoundment failure on chemical, physical, and microbial properties of substrates within the affected watershed, comprised of 70 hectares of riparian wetlands and 40 km of stream and lake shore. We established a biomonitoring network in October of 2014, two months following the disturbance, and evaluated riparian and wetland substrates for microbial community composition and function via 16S and full metagenome sequencing. A total of 234 samples were collected from substrates at 3 depths and 1,650,752 sequences were recorded in a geodatabase framework. These data revealed a wealth of information regarding watershed-scale distribution of microbial community members, as well as community composition, structure, and response to disturbance. Substrates associated with the impact zone were distinct chemically as indicated by elevated pH, nitrate, and sulphate. The microbial community exhibited elevated metabolic capacity for selenate and sulfate reduction and an abundance of chemolithoautotrophs in the Thiobacillus thiophilus/T. denitrificans/T. thioparus clade that may contribute to nitrate attenuation within the affected watershed. The most impacted area (a 6 km stream connecting two lakes) exhibited 30% lower microbial diversity relative to the remaining sites. The tailings impoundment failure at Mount Polley Mine has provided a unique opportunity to evaluate functional and compositional diversity soon after a major catastrophic disturbance to assess metabolic potential for ecosystem recovery. PMID:29694379

Anion inhibition profiles of the γ-carbonic anhydrase from the pathogenic bacterium Burkholderia pseudomallei responsible of melioidosis and highly drug resistant to common antibiotics.

PubMed

Del Prete, Sonia; Vullo, Daniela; Di Fonzo, Pietro; Osman, Sameh M; AlOthman, Zeid; Supuran, Claudiu T; Capasso, Clemente

2017-01-15

Burkholderia pseudomallei is a Gram-negative saprophytic bacterium responsible of melioidosis, an endemic disease of tropical and sub-tropical regions of the world. A recombinant γ-CA (BpsγCA) identified in the genome of this bacterium was cloned and purified. Its catalytic activity and anion inhibition profiles were investigated. The enzyme was an efficient catalyst for the CO 2 hydration showing a k cat of 5.3×10 5 s -1 and k cat /K m of 2.5×10 7 M -1 ×s -1 . The best BpsγCA inhibitors were sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid, which showed K I in the range of 49-83μM (these inhibitors showed millimolar inhibition constant against hCA II), followed by diethyldithiocarbamate, selenate, tellurate, perrhenate, selenocyanate, trithiocarbonate, tetraborato, pyrophosphate, stannate, carbonate, bicarbonate, azide, cyanide, thiocyanate and cyanate with K I s in the range of 0.55-9.1mM. In our laboratories, work is in progress to resolve the X-ray crystal structures of BpsγCA, which may allow the development of small molecule inhibitors with desired properties for targeting and inhibiting specifically the bacterial over the human CAs, considering the fact that B. pseudomallei is involved in a serious bacterial disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

A short-term intervention with selenium affects expression of genes implicated in the epithelial-to-mesenchymal transition in the prostate

PubMed Central

Kok, Dieuwertje E.G.; Kiemeney, Lambertus A.L.M.; Verhaegh, Gerald W.; Schalken, Jack A.; van Lin, Emile N.J.T.; Michiel Sedelaar, J.P.; Alfred Witjes, J.; Hulsbergen - van de Kaa, Christina A.; van't Veer, Pieter; Kampman, Ellen; Afman, Lydia A.

2017-01-01

In parallel with the inconsistency in observational studies and chemoprevention trials, the mechanisms by which selenium affects prostate cancer risk have not been elucidated. We conducted a randomized, placebo-controlled trial to examine the effects of a short-term intervention with selenium on gene expression in non-malignant prostate tissue. Twenty-three men received 300 μg selenium per day in the form of selenized yeast (n=12) or a placebo (n=11) during 5 weeks. Prostate biopsies collected from the transition zone before and after intervention were analysed for 15 participants (n=8 selenium, n=7 placebo). Pathway analyses revealed that the intervention with selenium was associated with down-regulated expression of genes involved in cellular migration, invasion, remodeling and immune responses. Specifically, expression of well-established epithelial markers, such as E-cadherin and epithelial cell adhesion molecule EPCAM, was up-regulated, while the mesenchymal markers vimentin and fibronectin were down-regulated after intervention with selenium. This implies an inhibitory effect of selenium on the epithelial-to-mesenchymal transition (EMT). Moreover, selenium was associated with down-regulated expression of genes involved in wound healing and inflammation; processes which are both related to EMT. In conclusion, our explorative data showed that selenium affected expression of genes implicated in EMT in the transition zone of the prostate. PMID:28076331

A short-term intervention with selenium affects expression of genes implicated in the epithelial-to-mesenchymal transition in the prostate.

PubMed

Kok, Dieuwertje E G; Kiemeney, Lambertus A L M; Verhaegh, Gerald W; Schalken, Jack A; van Lin, Emile N J T; Sedelaar, J P Michiel; Witjes, J Alfred; Hulsbergen-van de Kaa, Christina A; van 't Veer, Pieter; Kampman, Ellen; Afman, Lydia A

2017-02-07

In parallel with the inconsistency in observational studies and chemoprevention trials, the mechanisms by which selenium affects prostate cancer risk have not been elucidated. We conducted a randomized, placebo-controlled trial to examine the effects of a short-term intervention with selenium on gene expression in non-malignant prostate tissue. Twenty-three men received 300 µg selenium per day in the form of selenized yeast (n=12) or a placebo (n=11) during 5 weeks. Prostate biopsies collected from the transition zone before and after intervention were analysed for 15 participants (n=8 selenium, n=7 placebo). Pathway analyses revealed that the intervention with selenium was associated with down-regulated expression of genes involved in cellular migration, invasion, remodeling and immune responses. Specifically, expression of well-established epithelial markers, such as E-cadherin and epithelial cell adhesion molecule EPCAM, was up-regulated, while the mesenchymal markers vimentin and fibronectin were down-regulated after intervention with selenium. This implies an inhibitory effect of selenium on the epithelial-to-mesenchymal transition (EMT). Moreover, selenium was associated with down-regulated expression of genes involved in wound healing and inflammation; processes which are both related to EMT. In conclusion, our explorative data showed that selenium affected expression of genes implicated in EMT in the transition zone of the prostate.

Selenium accumulation and metabolism in algae.

PubMed

Schiavon, Michela; Ertani, Andrea; Parrasia, Sofia; Vecchia, Francesca Dalla

2017-08-01

Selenium (Se) is an intriguing element because it is metabolically required by a variety of organisms, but it may induce toxicity at high doses. Algae primarily absorb selenium in the form of selenate or selenite using mechanisms similar to those reported in plants. However, while Se is needed by several species of microalgae, the essentiality of this element for plants has not been established yet. The study of Se uptake and accumulation strategies in micro- and macro-algae is of pivotal importance, as they represent potential vectors for Se movement in aquatic environments and Se at high levels may affect their growth causing a reduction in primary production. Some microalgae exhibit the capacity of efficiently converting Se to less harmful volatile compounds as a strategy to cope with Se toxicity. Therefore, they play a crucial role in Se-cycling through the ecosystem. On the other side, micro- or macro-algae enriched in Se may be used in Se biofortification programs aimed to improve Se content in human diet via supplementation of valuable food. Indeed, some organic forms of selenium (selenomethionine and methylselenocysteine) are known to act as anticarcinogenic compounds and exert a broad spectrum of beneficial effects in humans and other mammals. Here, we want to give an overview of the developments in the current understanding of Se uptake, accumulation and metabolism in algae, discussing potential ecotoxicological implications and nutritional aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrafast and sensitive photodetector based on a PtSe2/silicon nanowire array heterojunction with a multiband spectral response from 200 to 1550 nm

NASA Astrophysics Data System (ADS)

Zeng, Longhui; Lin, Shenghuang; Lou, Zhenhua; Yuan, Huiyu; Long, Hui; Li, Yanyong; Lu, Wei; Lau, Shu Ping; Wu, Di; Tsang, Yuen Hong

2018-04-01

The newly discovered Group-10 transition metal dichalcogenides (TMDs) like PtSe2 have promising applications in high-performance microelectronic and optoelectronic devices due to their high carrier mobilities, widely tunable bandages and ultrastabilities. However, the optoelectronic performance of broadband PtSe2 photodetectors integrated with silicon remains undiscovered. Here, we report the successful preparation of large-scale, uniform and vertically grown PtSe2 films by simple selenization method for the design of a PtSe2/Si nanowire array heterostructure, which exhibited a very good photoresponsivity of 12.65 A/W, a high specific detectivity of 2.5 × 1013 Jones at -5 V and fast rise/fall times of 10.1/19.5 μs at 10 kHz without degradation while being capable of responding to high frequencies of up to 120 kHz. Our work has demonstrated the compatibility of PtSe2 with the existing silicon technology and ultrabroad band detection ranging from deep ultraviolet to optical telecommunication wavelengths, which can largely cover the limitations of silicon detectors. Further investigation of the device revealed pronounced photovoltaic behavior at 0 V, making it capable of operating as a self-powered photodetector. Overall, this representative PtSe2/Si nanowire array-based photodetector offers great potential for applications in next-generation optoelectronic and electronic devices.

Melatonin mediates selenium-induced tolerance to cadmium stress in tomato plants.

PubMed

Li, Meng-Qi; Hasan, Md Kamrul; Li, Cai-Xia; Ahammed, Golam Jalal; Xia, Xiao-Jian; Shi, Kai; Zhou, Yan-Hong; Reiter, Russel J; Yu, Jing-Quan; Xu, Ming-Xing; Zhou, Jie

2016-10-01

Both selenium (Se) and melatonin reduce cadmium (Cd) uptake and mitigate Cd toxicity in plants. However, the relationship between Se and melatonin in Cd detoxification remains unclear. In this study, we investigated the influence of three forms of Se (selenocysteine, sodium selenite, and sodium selenate) on the biosynthesis of melatonin and the tolerance against Cd in tomato plants. Pretreatment with different forms of Se significantly induced the biosynthesis of melatonin and its precursors (tryptophan, tryptamine, and serotonin); selenocysteine had the most marked effect on melatonin biosynthesis. Furthermore, Se and melatonin supplements significantly increased plant Cd tolerance as evidenced by decreased growth inhibition, photoinhibition, and electrolyte leakage (EL). Se-induced Cd tolerance was compromised in melatonin-deficient plants following tryptophan decarboxylase (TDC) gene silencing. Se treatment increased the levels of glutathione (GSH) and phytochelatins (PCs), as well as the expression of GSH and PC biosynthetic genes in nonsilenced plants, but the effects of Se were compromised in TDC-silenced plants under Cd stress. In addition, Se and melatonin supplements reduced Cd content in leaves of nonsilenced plants, but Se-induced reduction in Cd content was compromised in leaves of TDC-silenced plants. Taken together, our results indicate that melatonin is involved in Se-induced Cd tolerance via the regulation of Cd detoxification. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method.

PubMed

Diao, Chien-Chen; Kuo, Hsin-Hui; Tzou, Wen-Cheng; Chen, Yen-Lin; Yang, Cheng-Fu

2014-01-03

In this study, a new thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CuInSe₂ absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe₂ precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe₂ absorber layers. After spraying on Mo/glass substrates, the CuInSe₂ thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N₂ as atmosphere. When the CuInSe₂ thin films were annealed, without extra Se or H₂Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe₂ absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe₂ absorber layers could be controlled as the volume of used dispersed CuInSe₂-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe₂ absorber layers obtained by the Spray Coating Method.

Rational Design of Hierarchical Nanotubes through Encapsulating CoSe2 Nanoparticles into MoSe2/C Composite Shells with Enhanced Lithium and Sodium Storage Performance.

PubMed

Gao, Jingyu; Li, Yapeng; Shi, Liang; Li, Jingjing; Zhang, Genqiang

2018-06-20

Transition-metal diselenides have been extensively studied as desirable anode candidates for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical capacities. However, it is of great challenge to achieve satisfactory cycling performance, especially for larger sodium ion storage, originated from electrode deterioration upon large volume change. Herein, we reported the construction of hierarchical tubular hybrid nanostructures through encapsulating CoSe 2 nanoparticles into MoSe 2 /C composite shells via a simple two-step strategy including a hydrothermal method followed by vapor-phase selenization process. The unique tubular structure enables the highly reversible Li/Na storage with high specific capacity, enhanced cycling stability, and superior rate performance. It is indicated that the contribution of partial pseudocapacitive behavior greatly improves the rate capability for SIBs, where a high capacity retention of 81.5% can be obtained when the current densities range from 0.1 to 3 A g -1 (460 mA h g -1 at 0.1 A g -1 vs 379 mA h g -1 at 3 A g -1 ). This work provides an effective design rationale on transition-metal diselenide-based tubular nanostructures as superior hosts for both Li and Na ions, which could push forward the development of practical applications of transition-metal diselenide-based anodes in LIBs and SIBs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horowitz, Kelsey A. W.; Fu, Ran; Woodhouse, Michael

This article examines current cost drivers and potential avenues to reduced cost for monolithic, glass-glass Cu(In,Ga)(Se,S)2 (CIGS) modules by constructing a comprehensive bottom-up cost model. For a reference case where sputtering plus batch sulfurization after selenization (SAS) is employed, we compute a manufacturing cost of $69/m2 if the modules are made in the United States at a 1 GW/year production volume. At 14% module efficiency, this corresponds to a manufacturing cost of $0.49/WDC and a minimum sustainable price (MSP) of $0.67/WDC. We estimate that MSP could vary within +/-20% of this value given the range of quoted input prices, andmore » existing variations in module design, manufacturing processes, and manufacturing location. Potential for reduction in manufacturing costs to below $0.40/WDC may be possible if average production module efficiencies can be increased above 17% without increasing $/m2 costs; even lower costs could be achieved if $/m2 costs could be reduced, particularly via innovations in the CIGS deposition process or balance-of-module elements. We present the impact on cost of regional factors, CIGS deposition method, device design, and price fluctuations. One metric of competitiveness-levelized cost of energy (LCOE) -- is also assessed for several U.S. locations and compared to that of standard multi-crystalline silicon (m(c-Si)) and cadmium telluride (CdTe).« less

Enrichment and isolation of Bacillus beveridgei sp. nov., a facultative anaerobic haloalkaliphile from Mono Lake, California, that respires oxyanions of tellurium, selenium, and arsenic

USGS Publications Warehouse

Baesman, S.M.; Stolz, J.F.; Kulp, T.R.; Oremland, R.S.

2009-01-01

Mono Lake sediment slurries incubated with lactate and tellurite [Te(IV)] turned progressively black with time because of the precipitation of elemental tellurium [Te(0)]. An enrichment culture was established from these slurries that demonstrated Te(IV)-dependent growth. The enrichment was purified by picking isolated black colonies from lactate/Te(IV) agar plates, followed by repeated streaking and picking. The isolate, strain MLTeJB, grew in aqueous Te(IV)-medium if provided with a small amount of sterile solid phase material (e.g., agar plug; glass beads). Strain MLTeJB grew at high concentrations of Te(IV) (~8 mM) by oxidizing lactate to acetate plus formate, while reducing Te(IV) to Te(0). Other electron acceptors that were found to sustain growth were tellurate, selenate, selenite, arsenate, nitrate, nitrite, fumarate and oxygen. Notably, growth on arsenate, nitrate, nitrite and fumarate did not result in the accumulation of formate, implying that in these cases lactate was oxidized to acetate plus CO2. Strain MLTeJB is a low G + C Gram positive motile rod with pH, sodium, and temperature growth optima at 8.5-9.0, 0.5-1.5 M, and 40??C, respectively. The epithet Bacillus beveridgei strain MLTeJBT is proposed. ?? 2009 Springer.

Molecular properties of the SLC13 family of dicarboxylate and sulfate transporters

PubMed Central

Pajor, Ana M.

2006-01-01

The SLC13 gene family consists of five members in humans, with corresponding orthologs from different vertebrate species. All five genes code for sodium-coupled transporters that are found on the plasma membrane. Two of the transporters, NaS1 and NaS2, carry substrates such as sulfate, selenate and thiosulfate. The other members of the family (NaDC1, NaDC3, and NaCT) are transporters for di- and tri-carboxylates including succinate, citrate and α-ketoglutarate. The SLC13 transporters from vertebrates are electrogenic and they produce inward currents in the presence of sodium and substrate. Substrate-independent leak currents have also been described. Structure–function studies have identified the carboxy terminal half of these proteins as the most important for determining function. Transmembrane helices 9 and 10 may form part of the substrate permeation pathway and participate in conformational changes during the transport cycle. This review also discusses new members of the SLC13 superfamily that exhibit both sodium-dependent and sodium-independent transport mechanisms. The Indy protein from Drosophila, involved in determining lifespan, and the plant vacuolar malate transporter are both sodium-independent dicarboxylate transporters, possibly acting as exchangers. The purpose of this review is to provide an update on new advances in this gene family, particularly on structure–function studies and new members of the family. PMID:16211368

Development of a titanium dioxide-coated microfluidic-based photocatalyst-assisted reduction device to couple high-performance liquid chromatography with inductively coupled plasma-mass spectrometry for determination of inorganic selenium species.

PubMed

Shih, Tsung-Ting; Lin, Cheng-Hsing; Hsu, I-Hsiang; Chen, Jian-Yi; Sun, Yuh-Chang

2013-11-05

We developed a selective and sensitive hyphenated system employing a microfluidic-based vapor generation (VG) system in conjunction with high-performance liquid chromatography (HPLC) separation and inductively coupled plasma-mass spectrometry (ICPMS) detection for the determination of trace inorganic selenium (Se) species. The VG system exploited poly(methyl methacrylate) (PMMA) substrates of high optical quality to fabricate a microfluidic-based photocatalyst-assisted reduction device (microfluidic-based PCARD). Moreover, to reduce the consumption of photocatalysts during analytical procedures, a microfluidic-based PCARD coated with titanium dioxide nanoparticles (nano-TiO2) was employed to avoid consecutive loading. Notably, to simplify the coating procedure and improve the stability of the coating materials, a dynamic coating method was utilized. Under the optimized conditions for the selenicals of interest, the online HPLC/TiO2-coated microfluidic-based PCARD/ICPMS system enabled us to achieve detection limits (based on 3σ) of 0.043 and 0.042 μg L(-1) for Se(IV) and Se(VI), respectively. Both Se(IV) and Se(VI) could be efficiently vaporized within 15 s, while a series of validation experiments indicated that our proposed method could be satisfactorily applied to the determination of inorganic Se species in the environmental water samples.

Electrochemical vapor generation of selenium species after online photolysis and reduction by UV-irradiation under nano TiO2 photocatalysis and its application to selenium speciation by HPLC coupled with atomic fluorescence spectrometry.

PubMed

Liang, Jing; Wang, Qiuquan; Huang, Benli

2005-01-01

An online UV photolysis and UV/TiO2 photocatalysis reduction device (UV-UV/TiO2 PCRD) and an electrochemical vapor generation (ECVG) cell have been used for the first time as an interface between high-performance liquid chromatography (HPLC) and atomic fluorescence spectrometry (AFS) for selenium speciation. The newly designed ECVG cell of approximately 115 microL dead volume consists of a carbon fiber cathode and a platinum loop anode; the atomic hydrogen generated on the cathode was used to reduce selenium to vapor species for AFS determination. The noise was greatly reduced compared with that obtained by use of the UV-UV/TiO2 PCRD-KBH4-acid interface. The detection limits obtained for seleno-DL: -cystine (SeCys), selenite (Se(IV)), seleno-DL: -methionine (SeMet), and selenate (Se(VI)) were 2.1, 2.9, 4.3, and 3.5 ng mL(-1), respectively. The proposed method was successfully applied to the speciation of selenium in water-soluble extracts of garlic shoots cultured with different selenium species. The results obtained suggested that UV-UV/TiO2 PCRD-ECVG should be an effective interface between HPLC and AFS for the speciation of elements amenable to vapor generation, and is superior to methods involving KBH4.

Determination of changes in the concentration and distribution of elements within olive drupes (cv. Leccino) from Se biofortified plants, using laser ablation inductively coupled plasma mass spectrometry.

PubMed

D'Amato, Roberto; Petrelli, Maurizio; Proietti, Primo; Onofri, Andrea; Regni, Luca; Perugini, Diego; Businelli, Daniela

2018-03-25

Biofortification of food crops has been used to increase the intake of Se in the human diet, even though this may change the concentration of other elements and modify the nutritional properties of the enriched food. Selenium biofortification programs should include routine assessment of the overall mineral composition of enriched plants. Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) was used for the assessment of mineral composition of table olives. Olive trees were fertilized with sodium selenate before flowering. At harvest, the edible parts of drupes proved to be significantly enriched in Se, delivering 6.1 μg g -1 (39% of the RDA for five olives). Such enrichment was followed by significant changes in the concentrations of B, Mg, K, Cr, Mn, Fe and Cu in edible parts, which are discussed for their impact on food quality. The biofortification of olive plants has allowed the enrichment of fruits with selenium. Enrichment with selenium has caused an increase in the concentration of other elements, which can change the nutritional quality of the drupes. The analytical technique used well as a valuable tool for routinely determining the chemical composition of all fruit parts. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

Transport of chromium and selenium in the suboxic zone of a shallow aquifer: Influence of redox and adsorption reactions

USGS Publications Warehouse

Kent, D.B.; Davis, J.A.; Anderson, L.C.D.; Rea, B.A.; Waite, T.D.

1994-01-01

Breakthrough of Cr(VI) (chromate), Se(VI) (selenate), and O2 (dissolved oxygen) was observed in tracer tests conducted in a shallow, sand and gravel aquifer with mildly reducing conditions. Loss of Cr, probably due to reduction of Cr(VI) to Cr(III) and irreversible sorption of Cr(III), occurred along with slight retardation of Cr(VI), owing to reversible sorption. Reduction of Se(VI) and O2 was thermodynamically feasible but did not occur, indicating conditions, were unfavorable to microbial reduction. Cr(VI) reduction by constituents of aquifer sediments did not achieve local equilibrium during transport. The reduction rate was probably limited by incomplete contact between Cr(VI) transported along predominant flow paths and reductants located in regions within aquifer sediments of comparatively low permeability. Scatter in the amount of Cr reduction calculated from individual breakthrough curves at identical distances downgradient probably resulted from heterogeneities in the distribution of reductants in the sediments. Predictive modeling of the transport and fate of redox-sensitive solutes cannot be based strictly on thermodynamic considerations; knowledge of reaction rates is critical. Potentially important mass transfer rate limitations between solutes and reactants in sediments as well as heterogeneities in the distribution of redox properties in aquifers complicate determination of limiting rates for use in predictive simulations of the transport of redox-sensitive contaminants in groundwater.

Lunar Pit Craters Presumed to be the Entrances of Lava Caves by Analogy to the Earth Lava Tube Pits

NASA Astrophysics Data System (ADS)

Hong, Ik-Seon; Yi, Yu; Kim, Eojin

2014-06-01

Lava caves could be useful as outposts for the human exploration of the Moon. Lava caves or lava tubes are formed when the external surface of the lava flows cools more quickly to make a hardened crust over subsurface lava flows. The lava flow eventually ceases and drains out of the tube, leaving an empty space. The frail part of the ceiling of lava tube could collapse to expose the entrance to the lava tubes which is called a pit crater. Several pit craters with the diameter of around 100 meters have been found by analyzing the data of SELENE and LRO lunar missions. It is hard to use these pit craters for outposts since these are too large in scale. In this study, small scale pit craters which are fit for outposts have been investigated using the NAC image data of LROC. Several topographic patterns which are believed to be lunar caves have been found and the similar pit craters of the Earth were compared and analyzed to identify caves. For this analysis, the image data of satellites and aerial photographs are collected and classified to construct a database. Several pit craters analogous to lunar pit craters were derived and a morphological pit crater model was generated using the 3D printer based on this database.

Understanding reduced inorganic mercury accumulation in rice following selenium application: Selenium application routes, speciation and doses.

PubMed

Tang, Wenli; Dang, Fei; Evans, Douglas; Zhong, Huan; Xiao, Lin

2017-02-01

Selenium (Se) has recently been demonstrated to reduce inorganic mercury (IHg) accumulation in rice plants, while its mechanism is far from clear. Here, we aimed at exploring the potential effects of Se application routes (soil or foliar application with Se), speciation (selenite and selenate), and doses on IHg-Se antagonistic interactions in soil-rice systems. Results of our pot experiments indicated that soil application but not foliar application could evidently reduce tissue IHg concentrations (root: 0-48%, straw: 15-58%, and brown rice: 26-74%), although both application routes resulted in comparable Se accumulation in aboveground tissues. Meanwhile, IHg distribution in root generally increased with amended Se doses in soil, suggesting antagonistic interactions between IHg and Se in root. These results provided initial evidence that IHg-Se interactions in the rhizosphere (i.e., soil or rice root), instead of those in the aboveground tissues, could probably be more responsible for the reduced IHg bioaccumulation following Se application. Furthermore, Se dose rather than Se speciation was found to be more important in controlling IHg accumulation in rice. Our findings regarding the importance of IHg-Se interactions in the rhizosphere, together with the systematic investigation of key factors affecting IHg-Se antagonism and IHg bioaccumulation, advance our understanding of Hg dynamics in soil-rice systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of vertical and lateral distances between target and substrate in deposition process of CuGaSe 2 thin films using one-step sputtering

DOE PAGES

Park, Jae -Cheol; Al-Jassim, Mowafak; Kim, Tae -Won

2017-02-01

Here, copper gallium selenide (CGS) thin films were fabricated using a combinatorial one-step sputtering process without an additional selenization process. The sample libraries as a function of vertical and lateral distance from the sputtering target were synthesized on a single soda-lime glass substrate at the substrate temperature of 500 °C employing a stoichiometric CGS single target. As we increased the vertical distance between the target and substrate, the CGS thin films had more stable and uniform characteristics in structural and chemical properties. Under the optimized conditions of the vertical distance (150 mm), the CGS thin films showed densely packed grainsmore » and large grain sizes up to 1 μm in scale with decreasing lateral distances. The composition ratio of Ga/[Cu+Ga] and Se/[Cu+Ga] showed 0.50 and 0.93, respectively, in nearly the same composition as the sputtering target. X-ray diffraction and Raman spectroscopy revealed that the CGS thin films had a pure chalcopyrite phase without any secondary phases such as Cu–Se or ordered vacancy compounds, respectively. In addition, we found that the optical bandgap energies of the CGS thin films are shifted from 1.650 to 1.664 eV with decreasing lateral distance, showing a near-stoichiometric region with chalcopyrite characteristics.« less

The need for a reassessment of the safe upper limit of selenium in drinking water.

PubMed

Vinceti, Marco; Crespi, Catherine M; Bonvicini, Francesca; Malagoli, Carlotta; Ferrante, Margherita; Marmiroli, Sandra; Stranges, Saverio

2013-01-15

Results of recent epidemiologic studies suggest the need to reassess the safe upper limit in drinking water of selenium, a metalloid with both toxicological and nutritional properties. Observational and experimental human studies on health effects of organic selenium compounds consumed through diet or supplements, and of inorganic selenium consumed through drinking water, have shown that human toxicity may occur at much lower levels than previously surmised. Evidence indicates that the chemical form of selenium strongly influences its toxicity, and that its biological activity may differ in different species, emphasizing the importance of the few human studies on health effects of the specific selenium compounds found in drinking water. Epidemiologic studies that investigated the effects of selenate, an inorganic selenium species commonly found in drinking water, together with evidence of toxicity of inorganic selenium at low levels in from in vitro and animal studies, indicate that health risks may occur at exposures below the current European Union and World Health Organization upper limit and guideline of 10 and 40 μg/l, respectively, and suggest reduction to 1 μg/l in order to adequately protect human health. Although few drinking waters are currently known to have selenium concentrations exceeding this level, the public health importance of this issue should not be overlooked, and further epidemiologic research is critically needed in this area. Copyright © 2012 Elsevier B.V. All rights reserved.

Mechanistic understanding of MeHg-Se antagonism in soil-rice systems: the key role of antagonism in soil

PubMed Central

Wang, Yongjie; Dang, Fei; Evans, R. Douglas; Zhong, Huan; Zhao, Jiating; Zhou, Dongmei

2016-01-01

Methylmercury (MeHg) accumulation in rice has great implications for human health. Here, effects of selenium (Se) on MeHg availability to rice are explored by growing rice under soil or foliar fertilization with Se. Results indicate that soil amendment with Se could reduce MeHg levels in soil and grain (maximally 73%). In contrast, foliar fertilization with Se enhanced plant Se levels (3–12 folds) without affecting grain MeHg concentrations. This evidence, along with the distinct distribution of MeHg and Se within the plant, demonstrate for the first time that Se-induced reduction in soil MeHg levels (i.e., MeHg-Se antagonism in soil) rather than MeHg-Se interactions within the plant might be the key process triggering the decreased grain MeHg levels under Se amendment. The reduction in soil MeHg concentrations could be mainly attributed to the formation of Hg-Se complexes (detected by TEM-EDX and XANES) and thus reduced microbial MeHg production. Moreover, selenite and selenate were equally effective in reducing soil MeHg concentrations, possibly because of rapid changes in Se speciation. The dominant role of Se-induced reduction in soil MeHg levels, which has been largely underestimated previously, together with the possible mechanisms advance our mechanistic understanding about MeHg dynamics in soil-rice systems. PMID:26778218

Toenail selenium as an indicator of environmental exposure: A cross-sectional study.

PubMed

Filippini, Tommaso; Ferrari, Angela; Michalke, Bernhard; Grill, Peter; Vescovi, Luciano; Salvia, Chiara; Malagoli, Carlotta; Malavolti, Marcella; Sieri, Sabina; Krogh, Vittorio; Bargellini, Annalisa; Martino, Antonio; Ferrante, Margherita; Vinceti, Marco

2017-05-01

The relation between toxicity and essentiality of selenium (Se) is of growing interest in human health, as the effects may widely differ depending of its different chemical species and the exposure levels. Toenail Se has been proposed as a reliable biomarker of long-term Se exposure, but few studies investigated the correlation between its toenail content and environmental determinants (i.e., dietary food intake). We aimed to determine the relation of toenail Se levels with serum Se species as well as food items. We recruited a random sample of Modena (Northern Italy) municipal residents, from whom we collected detailed personal information, dietary habits, toenail specimen for Se determination and a blood sample for serum Se speciation analysis. Toenail Se mean value was 0.96 µg/g (range, 0.47‑1.60), with slightly higher levels in females, in non-obese subjects and in Se supplements users, while it was lower in current smokers. Toenail Se positively correlated with organic Se forms, mainly selenoprotein P and selenocysteine, and inversely with the inorganic forms (selenite and selenate). Toenail Se was not associated with meat, cereals and dairy products consumption, positively correlated with fruit and slightly with vegetable intake, and negatively with fish and seafood consumption. Finally, no clear association emerged with estimated air Se exposure.

Distribution of selenium in zebrafish larvae after exposure to organic and inorganic selenium forms.

PubMed

Dolgova, N V; Hackett, M J; MacDonald, T C; Nehzati, S; James, A K; Krone, P H; George, G N; Pickering, I J

2016-03-01

Selenium is an essential micronutrient for many organisms, and in vertebrates has a variety of roles associated with protection from reactive oxygen species. Over the past two decades there have been conflicting reports upon human health benefits and detriments arising from consumption of selenium dietary supplements. Thus, early studies report a decrease in the incidence of certain types of cancer, whereas subsequent studies did not observe any anti-cancer effect, and adverse effects such as increased risks for type 2 diabetes have been reported. A possible contributing factor may be that different chemical forms of selenium were used in different studies. Using larval stage zebrafish (Danio rerio) as a model organism, we report a comparison of the toxicities and tissue selenium distributions of four different chemical forms of selenium. We find that the organic forms of selenium tested (Se-methyl-l-selenocysteine and l-selenomethionine) show considerably more toxicity than inorganic forms (selenite and selenate), and that this appears to be correlated with the level of bioaccumulation. Despite differences in concentrations, the tissue specific pattern of selenium accumulation was similar for the chemical forms tested; selenium was found to be highly concentrated in pigment (melanin) containing tissues especially for the organic selenium treatments, with lower concentrations in eye lens, yolk sac and heart. These results suggest that pigmented tissues might serve as a storage reservoir for selenium.

Opposing impacts on healthspan and longevity by limiting dietary selenium in telomere dysfunctional mice.

PubMed

Wu, Ryan T; Cao, Lei; Mattson, Elliot; Witwer, Kenneth W; Cao, Jay; Zeng, Huawei; He, Xin; Combs, Gerald F; Cheng, Wen-Hsing

2017-02-01

Selenium (Se) is a trace metalloid essential for life, but its nutritional and physiological roles during the aging process remain elusive. While telomere attrition contributes to replicative senescence mainly through persistent DNA damage response, such an aging process is mitigated in mice with inherently long telomeres. Here, weanling third generation telomerase RNA component knockout mice carrying short telomeres were fed a Se-deficient basal diet or the diet supplemented with 0.15 ppm Se as sodium selenate to be nutritionally sufficient throughout their life. Dietary Se deprivation delayed wound healing and accelerated incidence of osteoporosis, gray hair, alopecia, and cataract, but surprisingly promoted longevity. Plasma microRNA profiling revealed a circulating signature of Se deprivation, and subsequent ontological analyses predicted dominant changes in metabolism. Consistent with this observation, dietary Se deprivation accelerated age-dependent declines in glucose tolerance, insulin sensitivity, and glucose-stimulated insulin production in the mice. Moreover, DNA damage and senescence responses were enhanced and Pdx1 and MafA mRNA expression were reduced in pancreas of the Se-deficient mice. Altogether, these results suggest a novel model of aging with conceptual advances, whereby Se at low levels may be considered a hormetic chemical and decouple healthspan and longevity. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE PAGES

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.; ...

2016-08-22

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

The fascinating facets of plant selenium accumulation - biochemistry, physiology, evolution and ecology.

PubMed

Schiavon, Michela; Pilon-Smits, Elizabeth A H

2017-03-01

Contents 1582 I. 1582 II. 1583 III. 1588 IV. 1590 V. 1592 1592 References 1592 SUMMARY: The importance of selenium (Se) for medicine, industry and the environment is increasingly apparent. Se is essential for many species, including humans, but toxic at elevated concentrations. Plant Se accumulation and volatilization may be applied in crop biofortification and phytoremediation. Topics covered here include beneficial and toxic effects of Se on plants, mechanisms of Se accumulation and tolerance in plants and algae, Se hyperaccumulation, and ecological and evolutionary aspects of these processes. Plant species differ in the concentration and forms of Se accumulated, Se partitioning at the whole-plant and tissue levels, and the capacity to distinguish Se from sulfur. Mechanisms of Se hyperaccumulation and its adaptive significance appear to involve constitutive up-regulation of sulfate/selenate uptake and assimilation, associated with elevated concentrations of defense-related hormones. Hyperaccumulation has evolved independently in at least three plant families, probably as an elemental defense mechanism and perhaps mediating elemental allelopathy. Elevated plant Se protects plants from generalist herbivores and pathogens, but also gives rise to the evolution of Se-resistant specialists. Plant Se accumulation affects ecological interactions with herbivores, pollinators, neighboring plants, and microbes. Hyperaccumulation tends to negatively affect Se-sensitive ecological partners while facilitating Se-resistant partners, potentially affecting species composition and Se cycling in seleniferous ecosystems. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

The effect of selenium and UV radiation on leaf traits and biomass production in Triticum aestivum L.

PubMed

Golob, Aleksandra; Kavčič, Jan; Stibilj, Vekoslava; Gaberščik, Alenka; Vogel-Mikuš, Katarina; Germ, Mateja

2017-02-01

UV radiation as an evolutionarily important environmental factor, significantly affects plants traits and alters the effects of other environmental factors. Single and combined effects of ambient UV radiation, its exclusion, and Se foliar treatments on Si concentrations and production of Si phytoliths in wheat (Triticum aestivum L.) cv. 'Reska' were studied. The effects of these treatments on growth parameters of the plants, structural and biochemical traits of the leaves, and interactions of the leaves with light, as Si incrustation is the first barrier to light at the leaf surface were also examined. Under ambient UV radiation and foliar treatment with 10mgL -1 sodium selenate solution, there was a trade-off between the plant investment in primary and secondary metabolism, as the production of UV-absorbing compounds was enhanced while photosynthetic pigment levels were reduced. Independent of Se treatment, ambient UV radiation lowered respiratory potential, Ca concentration, and leaf thickness, and increased Si concentration, Si phytoliths formation, and cuticle thickness. The Se treatment has little effect on plant traits and biomass production but it increased Se concentrations in the plants by >100-fold, independent of UV radiation. In combination with UV radiation Se strengthen the protection of plants against stress by increasing the amount of UV absorbing compounds, light reflectance and transmittance. Copyright © 2016 Elsevier Inc. All rights reserved.

Toxicity of inorganic and organic selenium to Daphnia magna (cladocera) and Chironomus riparius (diptera)

USGS Publications Warehouse

Ingersoll, Christopher G.; Dwyer, F.J.; May, T.W.

1990-01-01

Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase (r) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.

Pulse electro-deposition of copper on molybdenum for Cu(In,Ga)Se2 and Cu2ZnSnSe4 solar cell applications

NASA Astrophysics Data System (ADS)

Bi, Jinlian; Yao, Liyong; Ao, Jianping; Gao, Shoushuai; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Zhang, Yi

2016-09-01

The issues of rough surface morphology and the incorporated additives of the electro-deposited Cu layers, which exists in electrodeposition-based processes, is one of the major obstacles to improve the efficiency of Cu(In,Ga)Se2 (CIGSe) and Cu2ZnSnSe4 (CZTSe) solar cells. In this study, the pulse current electro-deposition method is employed to deposit smooth Cu film on Mo substrate in CuSO4 solution without any additives. Grain size of the deposited Cu film is decreased by high cathode polarization successfully. And the concentration polarization, which results from high pulse current density, is controlled successfully by adjusting the pulse frequency. Flat Cu film with smooth surface and compact structure is deposited as pulse current density @ 62.5 mA cm-2, pulse frequency @100,000 Hz, and duty cycle @ 25%. CIGSe and CZTSe absorber films with flat surface and uniform elemental distribution are prepared by selenizing the stacking metal layers electro-deposited by pulse current method. Finally, the CIGSe and CZTSe solar cells with conversion efficiency of 10.39% and 7.83% respectively are fabricated based on the smooth Cu films, which are better than the solar cells fabricated by the rough Cu film deposited by direct current electro-deposition method.

Glacial isostatic adjustment using GNSS permanent stations and GIA modelling tools

NASA Astrophysics Data System (ADS)

Kollo, Karin; Spada, Giorgio; Vermeer, Martin

2013-04-01

Glacial Isostatic Adjustment (GIA) affects the Earth's mantle in areas which were once ice covered and the process is still ongoing. In this contribution we focus on GIA processes in Fennoscandian and North American uplift regions. In this contribution we use horizontal and vertical uplift rates from Global Navigation Satellite System (GNSS) permanent stations. For Fennoscandia the BIFROST dataset (Lidberg, 2010) and North America the dataset from Sella, 2007 were used respectively. We perform GIA modelling with the SELEN program (Spada and Stocchi, 2007) and we vary ice model parameters in space in order to find ice model which suits best with uplift values obtained from GNSS time series analysis. In the GIA modelling, the ice models ICE-5G (Peltier, 2004) and the ice model denoted as ANU05 ((Fleming and Lambeck, 2004) and references therein) were used. As reference, the velocity field from GNSS permanent station time series was used for both target areas. Firstly the sensitivity to the harmonic degree was tested in order to reduce the computation time. In the test, nominal viscosity values and pre-defined lithosphere thicknesses models were used, varying maximum harmonic degree values. Main criteria for choosing the suitable harmonic degree was chi-square fit - if the error measure does not differ more than 10%, then one might use as well lower harmonic degree value. From this test, maximum harmonic degree of 72 was chosen to perform calculations, as the larger value did not significantly modify the results obtained, as well the computational time for observations was kept reasonable. Secondly the GIA computations were performed to find the model, which could fit with highest probability to the GNSS-based velocity field in the target areas. In order to find best fitting Earth viscosity parameters, different viscosity profiles for the Earth models were tested and their impact on horizontal and vertical velocity rates from GIA modelling was studied. For every tested model the chi-square misfit for horizontal, vertical and three-dimensional velocity rates from the reference model was found (Milne, 2001). Finally, the best fitting models from GIA modelling were compared with rates obtained from GNSS data. Keywords: Fennoscandia, North America, land uplift, glacial isostatic adjustment, visco-elastic modelling, BIFROST. References Lidberg, M., Johannson, J., Scherneck, H.-G. and Milne, G. (2010). Recent results based on continuous GPS observations of the GIA process in Fennoscandia from BIFROST. Journal of Geodynamics, 50. pp. 8-18. Sella, G. F., Stein, S., Dixon, T. H., Craymer, M., James, T. S., Mazotti, S. and Dokka, R. K. (2007). Observations of glacial isostatic adjustment in "stable" North America with GPS. Geophysical Research Letters, 34, L02306. Spada, G., Stocchi, P. (2007). SELEN: A Fortran 90 program for solving the "sea-level equation". Computers & Geosciences, 33:538-562, 2007. Peltier, W. R. (2004). Global glacial isostasy and the surface of the ice-age Earth: The Ice-5G (VM2) model and GRACE. Annu. Rev. Earth Planet. Sci., 32:111-149, 2004. Fleming, K. and Lambeck, K. (2004). Constraints on the Greenland Ice Sheet since the Last Glacial Maximum from sea-level observations and glacial-rebound models. Quaternary Science Reviews 23 (2004), pp. 1053-1077. Milne, G. A. and Davis, J. L. and Mitrovica, J. X. and Scherneck, H.-G. and Johansson, J. M. and Vermeer, M. and Koivula, H. (2001). Space-geodetic constraints on glacial isostatic adjustment in Fennoscandia. Science 291 (2001), pp. 2381-2385.

Rapid thermal processing for production of chalcopyrite thin films for solar cells: Design, analysis, and experimental implementation

NASA Astrophysics Data System (ADS)

Lovelett, Robert J.

The direct conversion of solar energy to electricity, or photovoltaic energy conversion, has a number of environmental, social, and economic advantages over conventional electricity generation from fossil fuels. Currently, the most commonly-used material for photovoltaics is crystalline silicon, which is now produced at large scale and silicon-based devices have achieved power conversion efficiencies over 25% However, alternative materials, such as inorganic thin films, offer a number of advantages including the potential for lower manufacturing costs, higher theoretical efficiencies, and better performance in the field. One of these materials is the chalcopyrite Cu(InGa)(SeS) 2, which has demonstrated module efficiencies over 17% and cell efficiencies over 22%. Cu(InGa)(SeS)2 is now in the early stages of commercialization using a precursor reaction process referred to as a "selenization/sulfization" reaction. The precursor reaction process is promising because it has demonstrated high efficiency along with the large area (approximately 1 m2) uniformity that is required for modules. However, some challenges remain that limit the growth of the chalcopyrite solar cell industry including: slow reactions that limit process throughput, a limited understanding of complex reaction kinetics and transport phenomena that affect the through-film composition, and the use of highly toxic H2Se in the reaction process. In this work, I approach each of these challenges. First, to improve process throughput, I designed and implemented a rapid thermal processing (RTP) reactor, whereby the samples are heated by a 1000 W quartz-halogen lamp that is capable of fast temperature ramps and high temperature dwells. With the reactor in place, however, achieving effective temperature control in the thin film material system is complicated by two intrinsic process characteristics: (i) the temperature of the Cu(InGa)(SeS)2 film cannot be measured directly, which leaves the system without complete state feedback; and (ii), the process is significantly nonlinear due to the dominance of radiative heat transfer at high temperatures. Therefore, I developed a novel control system using a first principles-based observer and a specialized temperature controller. Next, to understand the complex kinetics governing the selenization/sulfization processes, a stochastic model of solid state reaction kinetics was developed and applied to the system. The model is capable of predicting several important phenomena observed experimentally, including steep through-film gradients in gallium mole fraction. Furthermore, the model is mathematically general and can be useful for understanding a number of solid state reaction systems. Finally, the RTP system was then used to produce and characterize chalcopyrite films using two general methods: (i) single stage and multi stage reactions in H2Se and H2S, and (ii), reaction of a selenium "capped" precursor in H2S, where selenium was deposited on the precursor by thermal evaporation and the use of toxic H2Se was avoided. It was found that the processing conditions could be used to control material properties including relative sulfur incorporation, crystallinity, and through-film gallium and sulfur profiles. Films produced using the selenium-capped precursor reaction process were used to fabricate solar cell devices using a Mo/Cu(InGa)(SeS)2/CdS/ZnO/ITO substrate device structure, and the devices were tested by measuring the current-voltage characteristic under standard conditions. Devices with approximately 10% efficiency were obtained over a range of compositions and the best device obtained in this work had an efficiency of 12.7%.

Water selenium speciation and sediment fractionation in a California flow-through wetland system

USGS Publications Warehouse

Gao, S.; Tanii, K.K.; Peters, D.W.; Herbel, M.J.

2000-01-01

A flow-through wetland system was established in the Tulare Lake Drainage District (TLDD) in California to determine if selenium (Se) from saline irrigation drainage can be removed prior to impoundment in evaporation basins to reduce potential toxicity to waterbirds. The objective of this research was to evaluate Se speciation, accumulation, and fractionation in the waters and sediments of the newly developed wetland system. The inlet water was dominated by selenate [Se(VI), 92%], with smaller percentages of selenite [Se(IV), 5%] and organic Se [org-Se(-II), 3%]. For the outflow water, the average percentage of Se(VI) was 72% in November 1997 and 59% in February 1999. This change may be due to an increase in either residence time and/or accumulation of organic detrital matter, which may enhance Se(VI) reduction processes. Selenium accumulation, transformation, and incorporation with the solid phase were all intensified in the surface sediment (<20 cm). The highest total Se concentrations in the sediments were found in the top 5 cm and concentrations dramatically decreased with depth. Elemental Se [Se(0)], as extracted by Na2SO3, was the largest fraction (average of 46%) of the total sediment Se, followed by organic matter-associated Se (OM-Se) extracted by NaOH (average of 34%). Soluble, adsorbed, and carbonate-associated Se, as extracted by KCl, K2HPO4 (pH 8.0), and NaOAc (pH 5.0), were about 3, 10, and 3% of the total sediment Se, respectively. After establishing the wetland for 2 yr, significant Se removal from the flowing water was observed. The major sink mechanisms in the sediment are reduction to Se(0) and immobilization into the organic phase.A flow-through wetland system was established in the Tulare Lake Drainage District (TLDD) in California to determine if selenium (Se) from saline irrigation drainage can be removed prior to impoundment in evaporation basins to reduce potential toxicity to waterbirds. The objective of this research was to evaluate Se speciation, accumulation, and fractionation in the waters and sediments of the newly developed wetland system. The inlet water was dominated by selenate [Se(VI), 92%], with smaller percentages of selenite [Se(IV), 5%] and organic Se [org-Se(-II), 3%]. For the outflow water, the average percentage of Se(VI) was 72% in November 1997 and 59% in February 1999. This change may be due to an increase in either residence time and/or accumulation of organic detrital matter, which may enhance Se(VI) reduction processes. Selenium accumulation, transformation, and incorporation with the solid phase were all intensified in the surface sediment (<20 cm). The highest total Se concentrations in the sediments were found in the top 5 cm and concentrations dramatically decreased with depth. Elemental Se [Se(0)], as extracted by Na2SO3, was the largest fraction (average of 46%) of the total sediment Se, followed by organic matter-associated Se (OM-Se) extracted by NaOH (average of 34%). Soluble, adsorbed, and carbonate-associated Se, as extracted by KCl, K2HPO4 (pH 8.0), and NaOAc (pH 5.0), were about 3, 10, and 3% of the total sediment Se, respectively. After establishing the wetland for 2 yr, significant Se removal from the flowing water was observed. The major sink mechanisms in the sediment are reduction to Se(0) and immobilization into the organic phase.

Selenoamino Acid-Enriched Green Pea as a Value-Added Plant Protein Source for Humans and Livestock.

PubMed

Garousi, Farzaneh; Domokos-Szabolcsy, Éva; Jánószky, Mihály; Kovács, Andrea Balláné; Veres, Szilvia; Soós, Áron; Kovács, Béla

2017-06-01

Selenium deficiency in various degrees affects around 15% of the world's population, contributing to a variety of health problems. In this study, we examined the accumulation and biotransformation of soil applied Se-supplementation (sodium selenite and sodium selenate forms) at different concentrations, along with growth and yield formation of green pea, in a greenhouse experiment. Biotransformation of inorganic Se was evaluated using HPLC-ICP-MS for Se-species separation in the above ground parts of green pea. Results showed 3 mg kg -1 Se IV increased green pea growth biomarkers and also caused an increase in protein content in leaves by 17%. Selenomethionine represented 65% of the total selenium content in shoots, but was lower in pods and seeds (54 and 38%, respectively). Selenomethionine was the major species in all plant parts and the only organic selenium form in the lower Se IV concentration range. Elevating the dose of Se IV (≥30 mg kg -1 ) triggered detrimental effects on growth and protein content and caused higher accumulation of inorganic Se in forms of Se VI and Se IV . Selenocysteine, another organic form of proteinogenic amino acid, was determined when Se IV (≥10 mg kg -1 ) was applied in higher concentrations. Thus, agronomic biofortification using the appropriate chemical form and concentration of Se will have positive effects on green pea growth and its enriched shoots and seeds provide a value-added protein source for livestock and humans with significant increased selenomethionine.

Null Activity of Selenium and Vitamin E as Cancer Chemopreventive Agents in the Rat Prostate1

PubMed Central

McCormick, David L.; Rao, K.V.N.; Johnson, William D.; Bosland, Maarten C.; Lubet, Ronald A.; Steele, Vernon E.

2009-01-01

To evaluate the potential efficacy of selenium and vitamin E as inhibitors of prostate carcinogenesis, four chemoprevention studies using a common protocol were performed in a rat model of androgen-dependent prostate cancer. After stimulation of prostate epithelial cell proliferation by a sequential regimen of cyproterone acetate followed by testosterone propionate, male Wistar-Unilever rats received a single intravenous injection of N-methyl-N-nitrosourea (MNU) followed by chronic androgen stimulation via subcutaneous implantation of testosterone pellets. At one week post-MNU, groups of carcinogen-treated rats (39–44/group) were fed either basal diet or basal diet supplemented with L-selenomethionine (3 or 1.5 mg/kg diet; Study 1); DL-α-tocopherol (Vitamin E; 4000 or 2000 mg/kg diet; Study 2); L-selenomethionine + Vitamin E (3 + 2000 mg/kg diet or 3 + 500 mg/kg diet; Study 3), or selenized yeast (target selenium levels of 9 or 3 mg/kg diet; Study 4). Each chemoprevention study was terminated at 13 months post-MNU, and prostate cancer incidence was determined by histopathologic evaluation. No statistically significant reductions in prostate cancer incidence were identified in any group receiving dietary supplementation with selenium and/or vitamin E. These data do not support the hypotheses that selenium and vitamin E are potent cancer chemopreventive agents in the prostate, and when considered with the recent clinical data reported in the SELECT trial, demonstrate the predictive nature of this animal model for human prostate cancer chemoprevention. PMID:20145190

Magma source transition of lunar mare volcanism at 2.3 Ga

NASA Astrophysics Data System (ADS)

Kato, Shinsuke; Morota, Tomokatsu; Yamaguchi, Yasushi; Watanabe, Sei-Ichiro; Otake, Hisashi; Ohtake, Makiko

2017-09-01

Mare basalts provide insights into the composition and thermal history of the lunar mantle. The ages of mare basalts suggest a first peak of magma activity at 3.2-3.8 Ga and a second peak at 2 Ga. In this study, we reassess the correlation between the titanium contents and the eruption ages of mare basalt units using the compositional and chronological data updated by SELENE (Kaguya). Using morphological and geological criteria, we calculated the titanium content of 261 mare units across a representative area of each mare unit. In the Procellarum KREEP Terrane, where the latest eruptions are located, an increase in the mean titanium content is observed during the Eratosthenian period, as reported by previous studies. We found that the increase in the mean titanium content occurred within a relatively short period near approximately 2.3 Ga, suggesting that the magma source of the mare basalts changed at this particular age. Moreover, the high-titanium basaltic eruptions are correlated with a second peak in volcanic activity near 2 Ga. The high-titanium basaltic eruptions occurring during the last volcanic activity period can be explained by the three possible scenarios (1) the ilmenite-bearing cumulate rich layer in the core-mantle boundary formed after the mantle overturn, (2) the basaltic material layers beneath the lunar crust formed through upwelling magmas, and (3) ilmenite-bearing cumulate blocks remained in the upper mantle after the mantle overturn.

Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method

PubMed Central

Diao, Chien-Chen; Kuo, Hsin-Hui; Tzou, Wen-Cheng; Chen, Yen-Lin; Yang, Cheng-Fu

2014-01-01

In this study, a new thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CuInSe2 absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe2 precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe2 absorber layers. After spraying on Mo/glass substrates, the CuInSe2 thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N2 as atmosphere. When the CuInSe2 thin films were annealed, without extra Se or H2Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe2 absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe2 absorber layers could be controlled as the volume of used dispersed CuInSe2-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe2 absorber layers obtained by the Spray Coating Method. PMID:28788451

Identification of trace levels of selenomethionine and related organic selenium species in high-ionic-strength waters.

PubMed

LeBlanc, Kelly L; Ruzicka, Josef; Wallschläger, Dirk

2016-02-01

A new anion-exchange chromatographic separation method was used for the simultaneous speciation analysis of selenoamino acids and the more ubiquitous inorganic selenium oxyanions, selenite and selenate. For quantification, this separation was coupled to inductively coupled plasma-mass spectrometry to achieve an instrumental detection limit of 5 ng Se L(-1) for all species. This chromatographic method was also coupled to electrospray tandem mass spectrometry to observe the negative ion mode fragmentation of selenomethionine and one of its oxidation products. Low detection limits were achieved, which were similar to those obtained using inductively coupled plasma-mass spectrometry. An extensive preconcentration and cleanup procedure using cation-exchange solid-phase extraction was developed for the identification and quantification of trace levels of selenomethionine in environmental samples. Preconcentration factors of up to five were observed for selenomethionine, which in addition to the removal of high concentrations of sulphate and chloride from industrial process waters, allowed for an unambiguous analysis that would have been impossible otherwise. Following these methods, selenomethionine was identified at an original concentration of 3.2 ng Se L(-1) in samples of effluent collected at a coal-fired power plant's biological remediation site. It is the first time that this species has been identified in the environment, outside of a biological entity. Additionally, oxidation products of selenomethionine were identified in river water and laboratory algal culture samples. High-resolution mass spectrometry was employed to postulate the chemical structures of these species.

Laboratory studies of magnetic anomaly effects on electric potential distributions near the lunar surface

NASA Astrophysics Data System (ADS)

Wang, X.; Robertson, S. H.; Horanyi, M.; NASA Lunar Science Institute: Colorado CenterLunar Dust; Atmospheric Studies

2011-12-01

The Moon does not have a global magnetic field, unlike the Earth, rather it has strong crustal magnetic anomalies. Data from Lunar Prospector and SELENE (Kaguya) observed strong interactions between the solar wind and these localized magnetic fields. In the laboratory, a configuration of a horseshoe permanent magnet below an insulating surface is used as an analogue of lunar crustal magnetic anomalies. Plasmas are created above the surface by a hot filament discharge. Potential distributions are measured with an emissive probe and show complex spatial structures. In our experiments, electrons are magnetized with gyro-radii r smaller than the distance from the surface d (r < d) and ions are un-magnetized with r > d. Unlike negative charging on surfaces with no magnetic fields, the surface potential at the center of the magnetic dipole is found close to the plasma bulk potential. The surface charging is dominated by the cold unmagnetized ions, while the electrons are shielded away. A potential minimum is formed between the center of the surface and the bulk plasma, most likely caused by the trapped electrons between the two magnetic mirrors at the cusps. The value of the potential minimum with respect to the bulk plasma potential decreases with increasing plasma density and neutral pressure, indicating that the mirror-trapped electrons are scattered by electron-electron and electron-neutral collisions. The potential at the two cusps are found to be more negative due to the electrons following the magnetic field lines onto the surface.

Respiratory enzymes of Thiobacillus ferrooxidans. Kinetic properties of an acid-stable iron:rusticyanin oxidoreductase.

PubMed

Blake, R C; Shute, E A

1994-08-09

Rusticyanin is an acid-stable, soluble blue copper protein found in abundance in the periplasmic space of Thiobacillus ferrooxidans, an acidophilic bacterium capable of growing autotrophically on soluble ferrous sulfate. An acid-stable iron:rusticyanin oxidoreductase activity was partially purified from cell-free extracts of T. ferrooxidans. The enzyme-catalyzed, iron-dependent reduction of the rusticyanin exhibited three kinetic properties characteristic of aerobic iron oxidation by whole cells. (i) A survey of 14 different anions indicated that catalysis by the oxidoreductase occurred only in the presence of sulfate or selenate, an anion specificity identical to that of whole cells. (ii) Saturation with both sulfatoiron(II) and the catalyst produced a concentration-independent rate constant of 3 s-1 for the reduction of the rusticyanin, which is an electron transfer reaction sufficiently rapid to account for the flux of electrons through the iron respiratory chain. (iii) Values for the enzyme-catalyzed pseudo-first-order rate constants for the reduction of the rusticyanin showed a hyperbolic dependence on the concentration of sulfatoiron(II) with a half-maximal effect at 300 microM, a value similar to the apparent KM for iron shown by whole cells. On the basis of these favorable comparisons between the behavior patterns of isolated biomolecules and those of whole cells, this iron:rusticyanin oxidoreductase is postulated to be the primary cellular oxidant of ferrous ions in the iron respiratory electron transport chain of T. ferrooxidans.