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Sample records for chromium selenides

  1. Chromium

    Science.gov (United States)

    ... health risks of too much chromium? Chromium and medication interactions Supplemental sources of chromium Chromium and Healthful Diets References Disclaimer What foods provide chromium? Chromium is widely distributed in the ...

  2. Formation of copper-indium-selenide and/or copper-indium-gallium-selenide films from indium selenide and copper selenide precursors

    Science.gov (United States)

    Curtis, Calvin J.; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S.; Nekuda, Jennifer A.

    2011-11-15

    Liquid-based indium selenide and copper selenide precursors, including copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent, are used to form crystalline copper-indium-selenide, and/or copper indium gallium selenide films (66) on substrates (52).

  3. Magnetic properties of Cr telluride-selenide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mankovsky, Sergey; Polesya, Svetlana; Ebert, Hubert [Dept. Chemie und Biochemie, Universitaet Muenchen, Butenandtstr. 5-13, D-81377 Muenchen (Germany); Huang, Zhong-Le; Bensch, Wolfgang [Institute for Anorganic Chemistry, Olshausenstr. 40, D-24098, Kiel (Germany)

    2007-07-01

    Results of a theoretical study of the magnetic properties of Cr telluride-selenide alloys having trigonal crystal structure are presented in comparison with experimental results. Both ground state and temperature-dependent magnetic properties of Cr{sub 1-{delta}}Te and Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} (with ratio {alpha}:{beta}=7:1,6:2,5:3) have been investigated in a wide region of chromium content. For the alloys Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} a transition to the state with antiferromagnetic order in a fully occupied sub-lattice and with no order in a partially occupied sub-lattice was obtained. For the alloys Li{sub x}Cr{sub 0.5}Ti{sub 0.75}Se{sub 2}, a non-monotonic dependence of structural and magnetic properties have been found upon increase of Li concentration x, that is in agreement with experimental results. The ground state properties have been studied on the basis of electronic structure calculations using the Korringa-Kohn-Rostoker (KKR) band structure method combined with the CPA alloy theory. Using Monte Carlo simulations we obtained the magnetic configuration at T=0 K and studied the magnetic properties at T>0 K as well. The required exchange coupling parameters were obtained from our ab-initio electronic structure calculations.

  4. Selenide isotope generator for the Galileo mission

    International Nuclear Information System (INIS)

    A significantly improved thermoelectric generator has been developed to provide electric power for NASA's Galileo Mission in 1982. Nominal power requirements for Galileo will be about 450 watts at BOL (Beginning of Life), and this will be furnished by two Selenide Isotope Generators (SIG) each powered by a Multi Hundred Watt (MHW) radioisotopic heat source. A Ground Demonstration System (GDS) of a nominal 100 w(e) features a 3M - produced selenide ring module around a shortened MHW-dimensioned electrical heat source, newly developed axially-grooved heat pipes on a disc-shaped radiator, and other innovations which will allow a full-sized generator's weight to be held at about 90 lbs

  5. Cybernetic prediction of selenide Chevreul's phases

    International Nuclear Information System (INIS)

    The method of training a computer is used to forecast the possibility for the formation of selenide Chevreul's phases of the Asub(x)Bsub(6)Sesub(8) composition (where A is any chemical element, B-Mo, Cr, W, Re). The peculiarities of applying cybernetic forecasting systems in inorganic chemistry are considered. The critical temperature of transfer into the superconducting state of some phases forecasted is estimated

  6. One Pot Synthetic Method of New Keto Diphenyl Selenide Compounds

    OpenAIRE

    Youcef Mechehoud; Benayache, F.; Benayache, S.; Mosset, P.

    2010-01-01

    A series of hitherto unreported mono- and di-keto diphenyl selenides have been efficiently synthesized in high yields by treatment of diphenyl selenide (1) with appropriately substituted acyl chloride using anhydrous aluminum chloride as catalyst and methylene chloride as solvent. The structures of the synthesized compounds have been confirmed by elemental and spectral analysis.

  7. Limiting pump intensity for sulfur-doped gallium selenide crystals

    International Nuclear Information System (INIS)

    High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium selenide)

  8. Improved thermoelectric performance of Nb-doped lead selenide

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yemao; Chen, Zhen; Xin, Caini [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Zhou, Min, E-mail: mzhou@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Huang, Rongjin [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-05

    Highlights: • Thermoelectric performance of Nb-doped lead selenide was investigated. • Higher Seebeck coefficient was obtained in Nb-doped lead selenide. • The grain sizes are about 100-300 nm according to SEM. • There is little lattice thermal conductivity decrease. - Abstract: In present work, niobium is used as donor impurity in lead selenide to increase carrier concentration. Thermoelectric transport properties of n-type Pb{sub 1.04−x}Nb{sub x}Se are investigated from room temperature to 673 K. Higher Seebeck coefficient is reached by Nb-doping in lead selenide compared to other dopants. The Seebeck coefficient enhancement comes from band modification by Nb-doping, which results in the density of states effective mass increase. With the Seebeck coefficient enhancement, the dimensionless figure of merit ZT reaches ∼1.1 at 673 K.

  9. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  10. Superconductivity in alkali metal intercalated iron selenides.

    Science.gov (United States)

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  11. Amphoteric properties of gold in zinc selenide

    International Nuclear Information System (INIS)

    Hall effect, electric conductivity, and charge carriers mobility in n-ZnSe single crystals doped with gold during the process of a long-term high-temperature annealing in Zn+Au melt with various Au contents were investigated in the temperature range from 77 to 300 K. It has been established that, at low gold concentration, Au atoms form mainly donor-type interstitial Aui defects. The increase of Au concentration in Zn+Au melt leads to the formation of both simple AuZn defects and associative acceptors (AuZn-Aui) (AuZn-DZn), and (AuZn-VSe). These defects determine electrical properties of the crystals and they are responsible for the complex structure of excitonic and impurity radiation spectra. The influence of dopant concentration on both electrical and luminescent properties of n-ZnSe:Zn:Au crystals is investigated. The observed variations of electrical and luminescent properties are due to amphoteric properties of gold impurity in zinc selenide

  12. Superconductivity in alkali metal intercalated iron selenides

    Science.gov (United States)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  13. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

    International Nuclear Information System (INIS)

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII−) as the precursor. Biogenic SeII− was produced by the reduction of SeIV by Veillonella atypica and compared directly against borohydride-reduced SeIV for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII− formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII− included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII− is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, ‘green’ synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams. (paper)

  14. Hexavalent Chromium Workshop

    Science.gov (United States)

    EPA is developing an updated IRIS assessment of hexavalent chromium. This assessment will evaluate the potential health effects of hexavalent chromium from oral and inhalation exposures. An important component of determining the cancer causing potential of ingested hexavalent chr...

  15. Chromium and Genomic Stability

    OpenAIRE

    Wise, Sandra S.; Wise, John Pierce

    2011-01-01

    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as high...

  16. Oxidation of chromium telluride

    International Nuclear Information System (INIS)

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation

  17. Oxidation of chromium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Pakhomovskaya, N.S.; Iorga, E.V.; Sheveleva, T.F.; Solov' eva, A.E.

    1986-03-01

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation.

  18. Mechanochemical synthesis of nanocrystalline lead selenide. Industrial approach

    Energy Technology Data Exchange (ETDEWEB)

    Achimovicova, Marcela; Balaz, Peter [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Geotechnics; Durisin, Juraj [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Materials Research; Daneu, Nina [Josef Stefan Institute, Ljubljana (Slovenia). Dept. for Nanostructured Materials; Kovac, Juraj; Satka, Alexander [Slovak Univ. of Technology and International Laser Centre, Bratislava (Slovakia). Dept. of Microelectronics; Feldhoff, Armin [Leibniz Univ. Hannover (Germany). Inst. fuer Physikalische Chemie und Elektrochemie; Gock, Eberhard [Technical Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Mineral and Waste Processing and Dumping Technology

    2011-04-15

    Mechanochemical synthesis of lead selenide PbSe nanoparticles was performed by high-energy milling of lead and selenium powder in a laboratory planetary ball mill and in an industrial eccentric vibratory mill. Structural properties of the synthesized lead selenide were characterized using X-ray diffraction that confirmed crystalline nature of PbSe nanoparticles. The average size of PbSe crystallites of 37 nm was calculated from X-ray diffraction data using the Williamson-Hall method. The methods of particle size distribution analysis, specific surface area measurement, scanning electron microscopy and transmission electron microscopy were used for characterization of surface, mean particle size, and morphology of PbSe. An application of industrial mill verified a possibility of the synthesis of a narrow bandgap semiconductor PbSe at ambient temperature and in a relatively short reaction time. (orig.)

  19. Strukturelle und kinetische Charakterisierung von Ruthenium-Selenid Katalysatoren

    OpenAIRE

    Racz, Alexander

    2011-01-01

    Die Arbeit befasst sich mit Kohlenstoff-geträgerten Ruthenium-Selenid (RuSex) Katalysatoren für die kathodische Sauerstoffreduktion in Methanol-Brennstoffzellen. Ziel dieser Arbeit war es, RuSex/C Katalysatoren zu synthetisieren, welche eine vergleichbare elektrochemische Aktivität wie kommerzielle Pt/C Katalysatoren aufweisen. Neben der Optimierung der Synthese stand die elektrochemische Charakterisierung der Katalysatoren im Hinblick auf die elektrochemisch aktive Oberfläche, sowie deren Ak...

  20. Long-term physical ageing in vitreous arsenic selenides

    International Nuclear Information System (INIS)

    Effects of long-term physical aging (approx 20 years) studied in vitreous arsenic selenides using differential scanning calorimetry are compared with conventional short-term physical aging (up to 1 year). It is shown that these effects differ not only by their amplitudes but also by compositional dependences. These results clearly testify in a favour of a sufficient difference in microstructural origin for short- and long-term physical aging in chalcogenide glasses

  1. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

    KAUST Repository

    Xia, Chuan

    2015-11-05

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  2. Synthesis of cadmium selenide colloidal quantum dots in aquatic medium

    International Nuclear Information System (INIS)

    Cadmium selenide nanocrystals were prepared in water phase through facile wet chemistry technique with thioglycolic acid (TGA) acting as capping agent. Structures were characterized using X-ray diffraction (XRD), UV-vis absorption and photoluminescence spectroscopies. Depending on synthesis conditions nanoparticles exhibit photoluminescence with maximum in the region of 580 – 680 nm. Influence of technological parameters and component concentrations on nanocrystals average size and properties was studied

  3. Coulometric titration at low temperatures-nonstoichiometric silver selenide

    OpenAIRE

    Beck, Gesa K.; Janek, Jürgen

    2003-01-01

    A modified coulometric titration technique is described for the investigation of nonstoichiometric phases at low temperatures. It allows to obtain titration curves at temperatures where the conventional coulometric titration technique fails because of too small chemical diffusion coefficients of the mobile component. This method for indirect coulometric titration is applied to silver selenide between -100 and 100 °C. The titration curves are analyzed on the basis of a defect chemical model an...

  4. Raman study of gallium selenide single crystal oxidation

    Directory of Open Access Journals (Sweden)

    O.A. Balitskii

    2001-06-01

    Full Text Available The Raman investigations on thermally oxidized gallium selenide were conducted. It was established that the oxidation of the GaSe involves the formation of a-modification of Ga2Se3 at the temperature up to 450 °C. The Ga-(O2 complexes are also detected at this temperature but the formation of crystalline gallium oxide takes place at the temperature of 800°C

  5. Hair chromium concentration and chromium excretion in tannery workers.

    OpenAIRE

    Saner, G; Yüzbasiyan, V; Cigdem, S

    1984-01-01

    Hair and urine samples were collected from 34 male tannery workers and from 12 normal adults. Eighteen of the workers dealt directly with chromium and the remaining 16 (controls) worked in the offices and kitchen of the same factory. All were found to be clinically healthy. Chromium was determined by flameless atomic absorption spectroscopy. When compared with normal adult values, urinary chromium concentration, Cr/Creatinine ratio, daily chromium excretion, and hair chromium, concentrations ...

  6. High-Purity Chromium Targets

    OpenAIRE

    Rudoy, A.; Milman, Yu.; Korzhova, N.

    1995-01-01

    A procedure for producing large-scale chromium ingots by means of induction-arc melting was developed. From the high-purity, low-alloyed chromium ingots obtained, chromium targets were produced by of thermoplastic treatment techniques. The method of electron-beam evaporation of high-purity chromium was also used for production of targets.

  7. Microstructural characterisation of chromium slags

    OpenAIRE

    Burja, J.; F. Tehovnik; Vode, F.; Arh, B.

    2015-01-01

    In this chromium slags that form during melting of chromium alloyed steels are examined. During melting and oxidation of these steel grades a considerable amount of chromium is lost, and gained back with slag reduction. Laboratory experiments were performed to study the mechanism of chromium oxide reduction by silicon. Slags chemistry and phase composition have a strong effect on the steelmaking process. Phase analysis revealed two types of chromium oxides, calcium chromites and chromite spin...

  8. Sodium selenide toxicity is mediated by O2-dependent DNA breaks.

    Directory of Open Access Journals (Sweden)

    Gérald Peyroche

    Full Text Available Hydrogen selenide is a recurrent metabolite of selenium compounds. However, few experiments studied the direct link between this toxic agent and cell death. To address this question, we first screened a systematic collection of Saccharomyces cerevisiae haploid knockout strains for sensitivity to sodium selenide, a donor for hydrogen selenide (H(2Se/HSe(-/Se(2-. Among the genes whose deletion caused hypersensitivity, homologous recombination and DNA damage checkpoint genes were over-represented, suggesting that DNA double-strand breaks are a dominant cause of hydrogen selenide toxicity. Consistent with this hypothesis, treatment of S. cerevisiae cells with sodium selenide triggered G2/M checkpoint activation and induced in vivo chromosome fragmentation. In vitro, sodium selenide directly induced DNA phosphodiester-bond breaks via an O(2-dependent reaction. The reaction was inhibited by mannitol, a hydroxyl radical quencher, but not by superoxide dismutase or catalase, strongly suggesting the involvement of hydroxyl radicals and ruling out participations of superoxide anions or hydrogen peroxide. The (•OH signature could indeed be detected by electron spin resonance upon exposure of a solution of sodium selenide to O(2. Finally we showed that, in vivo, toxicity strictly depended on the presence of O(2. Therefore, by combining genome-wide and biochemical approaches, we demonstrated that, in yeast cells, hydrogen selenide induces toxic DNA breaks through an O(2-dependent radical-based mechanism.

  9. Substoichiometric extraction of chromium

    International Nuclear Information System (INIS)

    Substoichiometric extraction of chromium with tetraphenylarsonium chloride (TPACl), tri-n-octylamine (TNOA), diethylammonium diethyldithiocarbamate (DDDC) and ammonium pyrrolidinedithiocarbamate (APDC) was examined in detail. Chromium can be extracted substoichiometrically in a pH range, which is 1.1-2.6 for the TPACl compound, 0.6-2.3 for the TNOA compound, 5.1-6.4 for the DDDC chelate and 3.9-4.9 for the APDC chelate. Chromium in high-purity calcium carbonate, Orchard Leaves (NBS SRM-1571) and Brewers Yeast (NBS SRM-1569) was determined by neutron activation analysis combined with substoichiometric extraction by DDDC and APDC. The values of 2.0+-0.02 ppm and 2.6+-0.2 ppm were obtained for Brewers Yeast and Orchard Leaves, respectively. These values were in good agreement with those reported by NBS. The reaction mechanism and the reaction ratio between hexavalent chromium and dithiocarbamate are also discussed. (author)

  10. Chromium in diet

    Science.gov (United States)

    ... Chromium deficiency may be seen as impaired glucose tolerance. It occurs in older people with type 2 ... PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health Topics Minerals Browse the Encyclopedia ...

  11. The carcinogenicity of chromium

    OpenAIRE

    Norseth, Tor

    1981-01-01

    The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Pres...

  12. Double-Diffusive Convection During Growth of Halides and Selenides

    Science.gov (United States)

    Singh, N. B.; Su, Ching-Hua; Duval, Walter M. B.

    2015-01-01

    Heavy metal halides and selenides have unique properties which make them excellent materials for chemical, biological and radiological sensors. Recently it has been shown that selenohalides are even better materials than halides or selenides for gamma-ray detection. These materials also meet the strong needs of a wide band imaging technology to cover ultra-violet (UV), midwave infrared wavelength (MWIR) to very long wavelength infrared (VLWIR) region for hyperspectral imager components such as etalon filters and acousto-optic tunable filters (AO). In fact AOTF based imagers based on these materials have some superiority than imagers based on liquid crystals, FTIR, Fabry-Perot, grating, etalon, electro-optic modulation, piezoelectric and several other concepts. For example, broadband spectral and imagers have problems of processing large amount of information during real-time observation. Acousto-Optic Tunable Filter (AOTF) imagers are being developed to fill the need of reducing processing time of data, low cost operation and key to achieving the goal of covering long-wave infrared (LWIR). At the present time spectral imaging systems are based on the use of diffraction gratings are typically used in a pushbroom or whiskbroom mode. They are mostly used in systems and acquire large amounts of hyperspectral data that is processed off-line later. In contrast, acousto-optic tunable filter spectral imagers require very little image processing, providing new strategies for object recognition and tracking. They are ideally suited for tactical situations requiring immediate real-time image processing. But the performance of these imagers depends on the quality and homogeneity of acousto-optic materials. In addition for many systems requirements are so demanding that crystals up to sizes of 10 cm length are desired. We have studied several selenides and halide crystals for laser and AO imagers for MWIR and LWIR wavelength regions. We have grown and fabricated crystals of

  13. Obtaining decorative chromium plating from trivalent chromium solutions

    OpenAIRE

    Óscar Javier Suárez García

    2010-01-01

    The present work was aimed at a qualitative evaluation, in the laboratory, of different alternatives for assembling and operating a trivalent chromium bath for decorative chromium plating. Different chromium concentration solutions and different complexing agents were used. The initial result of this analysis was that chloride, formate and acetate solutions produced the best results. Solution preparation conditions were evaluated: temperature, chromium III complex formation time and also ...

  14. Lithium insertion in indium selenide films: application to microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Julien, C. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Khelfa, A. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Benramdane, N. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Guesdon, J.P. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Dzwonkowski, P. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Samaras, I. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Balkanski, M. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France))

    1994-04-10

    Indium selenide films are formed on silica slides and silicon wafers using a flash evaporation technique in which the material source stoichiometry is modified to obtain In[sub p]Se[sub q] films with various compositions. The structural and optical properties of indium selenide films are reported. These characterizations have shown that, using different growth conditions, either single phases, such as InSe, In[sub 4]Se[sub 3] or In[sub 2]Se[sub 3], are formed or a mixture of these compounds is present in the film structure. The products are examined by X-ray diffraction, and Raman and IR spectroscopies. The electrochemical properties of lithium-intercalated films are presented. It is observed that the morphology and stoichiometry play an important role in the lithium insertion process. The thermodynamics and kinetics of the insertion reaction are reported. Li/Li[sup +]-borate glass/InSe microbatteries have been built, and their characteristics are reported and discussed using a Butler-Volmer relationship. (orig.)

  15. The analytical biochemistry of chromium.

    OpenAIRE

    Katz, S A

    1991-01-01

    The essentiality and carcinogenicity of chromium depend on its chemical form. Oxidation state and solubility are particularly important in determining the biological effects of chromium compounds. For this reason, total chromium measurements are of little value in assessing its nutritional benefits or its toxicological hazards. Aqueous sodium carbonate-sodium hydroxide solutions have been successfully used for extracting hexavalent chromium from a variety of environmental and biological matri...

  16. Chromium in potatoes

    International Nuclear Information System (INIS)

    Chromium concentration in potatoes was determined, and tubes were labeled either intrinsically or extrinsically with radioactive chromate (51Cr). A labeled chromium complex was isolated from preparations of raw, baked, or fried potatoes and chromatographed on gel permeation media. Potato pulp and peel contained 1.63 and 2.70 μg of Cr/g tissue, respectively. There was no correlation between the two, nor did they respond similarly to changes of variety or locations. No significant differences were apparent in relative migration of the isolated complexes except between raw and cooked extrinsically labeled preparations

  17. Chromium and aging

    Science.gov (United States)

    Aging is associated with increased blood glucose, insulin, blood lipids, and fat mass, and decreased lean body mass leading to increased incidences of diabetes and cardiovascular diseases. Improved chromium nutrition is associated with improvements in all of these variables. Insulin sensitivity de...

  18. Polystyrene-supported Benzyl Selenide: An Efficient Reagent for Highly Stereocontrolled Synthesis of Substituted Olefins

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Polystyrene-supported benzyl selenide has been prepared. This novel reagent was treated with LDA to produce a selenium stabilized carbanion, which reacted with alkyl halide, followed by selenoxide syn-elimination, to give substituted olefins stereospecificly.

  19. Manipulation of cadmium selenide nanorods with an atomic force microscope

    International Nuclear Information System (INIS)

    We have used an atomic force microscope (AFM) to manipulate and study ligand-capped cadmium selenide nanorods deposited on highly oriented pyrolitic graphite (HOPG). The AFM tip was used to manipulate (i.e., translate and rotate) the nanorods by applying a force perpendicular to the nanorod axis. The manipulation result was shown to depend on the point of impact of the AFM tip with the nanorod and whether the nanorod had been manipulated previously. Forces applied parallel to the nanorod axis, however, did not give rise to manipulation. These results are interpreted by considering the atomic-scale interactions of the HOPG substrate with the organic ligands surrounding the nanorods. The vertical deflection of the cantilever was recorded during manipulation and was combined with a model in order to estimate the value of the horizontal force between the tip and nanorod during manipulation. This horizontal force is estimated to be on the order of a few tens of nN.

  20. Selenide isotope generator for the Galileo mission. Reliability program plan

    International Nuclear Information System (INIS)

    The reliability program plan for the Selenide Isotope Generator (SIG) program is presented. It delineates the specific tasks that will be accomplished by Teledyne Energy Systems and its suppliers during design, development, fabrication and test of deliverable Radioisotopic Thermoelectric Generators (RTG), Electrical Heated Thermoelectric Generators (ETG) and associated Ground Support Equipment (GSE). The Plan is formulated in general accordance with procedures specified in DOE Reliability Engineering Program Requirements Publication No. SNS-2, dated June 17, 1974. The Reliability Program Plan presented herein defines the total reliability effort without further reference to Government Specifications. The reliability tasks to be accomplished are delineated herein and become the basis for contract compliance to the extent specified in the SIG contract Statement of Work

  1. Selenide isotope generator for the Galileo Mission. Program final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-06-01

    This final report for the Selenide Isotope Generator for the Galileo Mission (SIG/GM) documents the work performed by Teledyne Energy Systems (TES) under US Department of Energy (DOE) Contract No. DE-AC01-78ET33009 (formerly ET-78-C-01-2865) during the period April 10, 1978 to June 30, 1979. Because of technical difficulties with the thermoelectric converter being developed by the 3M Company under separate DOE contract, a Stop Work Order, dated January 29, 1979, was issued by DOE. The TES effort up to the receipt of the Stop Work Order as well as limited technical activities up to the contract conclusion on June 30, 1979 are reported.

  2. Hollow Cobalt Selenide Microspheres: Synthesis and Application as Anode Materials for Na-Ion Batteries.

    Science.gov (United States)

    Ko, You Na; Choi, Seung Ho; Kang, Yun Chan

    2016-03-16

    The electrochemical properties of hollow cobalt oxide and cobalt selenide microspheres are studied for the first time as anode materials for Na-ion batteries. Hollow cobalt oxide microspheres prepared by one-pot spray pyrolysis are transformed into hollow cobalt selenide microspheres by a simple selenization process using hydrogen selenide gas. Ultrafine nanocrystals of Co3O4 microspheres are preserved in the cobalt selenide microspheres selenized at 300 °C. The initial discharge capacities for the Co3O4 and cobalt selenide microspheres selenized at 300 and 400 °C are 727, 595, and 586 mA h g(-1), respectively, at a current density of 500 mA g(-1). The discharge capacities after 40 cycles for the same samples are 348, 467, and 251 mA h g(-1), respectively, and their capacity retentions measured from the second cycle onward are 66, 91, and 50%, respectively. The hollow cobalt selenide microspheres have better rate performances than the hollow cobalt oxide microspheres. PMID:26918934

  3. Studies of chromium gettering

    International Nuclear Information System (INIS)

    Preliminary results have shown that hydrogen pumping by chromium is a surface effect. Unlike with titanium, the getter material used in many present day tokamaks, there is no significant diffusion into the bulk. Additional experiments have been carried out to measure the basic characteristics of chromium films for gases of interest in tokamak research. These gases include deuterium, oxygen and nitrogen. A vacuum system is described which allowed precise control of the test gas, a constant wall temperature and determination of the projected getter surface area. A quadrupole mass spectrometer, rather than simply a total pressure gauge, was utilized to measure the partial pressure of the test gas as well as the residual gas composition in the system. A quartz crystal monitor was used to measure film thickness. Pumping speeds and sticking coefficients are given as a function of surface coverage for each test gas. A comparison will be made with titanium films deposited in the same vacuum system and under similar conditions

  4. Catalytic Spectrophotometric Determination of Chromium

    OpenAIRE

    STOYANOVA, Angelina Miltcheva

    2005-01-01

    The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL-1, and for chromium(VI) up to 200 ng mL-1) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL-1 and 3.8 ng mL-1, respectively...

  5. CHROMIUM, METABOLIC SYNDROME AND DIABESITY

    Science.gov (United States)

    Suboptimal intakes of the essential nutrient, chromium, are characterized by elevated blood glucose, insulin resistance, obesity, hypertriglyceridemia, and low HDL. These are also signs and symptoms of the metabolic syndrome. Improvements due to increased intake of chromium are related to the degr...

  6. Structure and photoluminescence of molybdenum selenide nanomaterials grown by hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Plasma Nanoscience Laboratories, Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, P. O. Box 218, Lindfield, NSW 2070 (Australia); Zhu, M.K. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Ostrikov, K., E-mail: kostya.ostrikov@qut.edu.au [Plasma Nanoscience Laboratories, Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, P. O. Box 218, Lindfield, NSW 2070 (Australia); Institute for Future Environments, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); Shao, R.W.; Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

    2015-10-25

    Molybdenum selenide nanomaterials with different structures are synthesized on silicon substrates coated with gold films by hot filament chemical vapor deposition (HFCVD) in nitrogen environment, where molybdenum trioxide and selenium powders are used as source materials. The structure and composition of the synthesized molybdenum selenide nanomaterials are studied using field emission scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the structures of molybdenum selenide change from nanoflakes to nanoparticles with the increase of content of molybdenum trioxide precursor. The photoluminescence (PL) excitation using the 325 nm line of He–Cd laser as the excitation source generates green light with the wavelength of about 512–516 nm. The formation of molybdenum selenide nanomaterials is determined by the decomposition rates of molybdenum trioxide in HFCVD. The possible factors that affect the generation of green PL bands are analyzed. These outcomes of this work enrich our knowledge on the synthesis of transition metal dichalcogenides and contribute to the development of applications of these materials in optoelectronic devices. - Highlights: • Molybdenum selenide nanoflakes, nanoparticles and hybrids produced by HFCVD. • Uncommon MoO{sub 3} and Se precursor co-location and mixing and effective MoO{sub 3} decomposition. • Morphology change from nanoflakes to nanoparticles with higher ratio of MoO{sub 3} precursor. • Strong photoluminescence emission of green light with a wavelength of ∼512–516 nm.

  7. Structure and photoluminescence of molybdenum selenide nanomaterials grown by hot filament chemical vapor deposition

    International Nuclear Information System (INIS)

    Molybdenum selenide nanomaterials with different structures are synthesized on silicon substrates coated with gold films by hot filament chemical vapor deposition (HFCVD) in nitrogen environment, where molybdenum trioxide and selenium powders are used as source materials. The structure and composition of the synthesized molybdenum selenide nanomaterials are studied using field emission scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the structures of molybdenum selenide change from nanoflakes to nanoparticles with the increase of content of molybdenum trioxide precursor. The photoluminescence (PL) excitation using the 325 nm line of He–Cd laser as the excitation source generates green light with the wavelength of about 512–516 nm. The formation of molybdenum selenide nanomaterials is determined by the decomposition rates of molybdenum trioxide in HFCVD. The possible factors that affect the generation of green PL bands are analyzed. These outcomes of this work enrich our knowledge on the synthesis of transition metal dichalcogenides and contribute to the development of applications of these materials in optoelectronic devices. - Highlights: • Molybdenum selenide nanoflakes, nanoparticles and hybrids produced by HFCVD. • Uncommon MoO3 and Se precursor co-location and mixing and effective MoO3 decomposition. • Morphology change from nanoflakes to nanoparticles with higher ratio of MoO3 precursor. • Strong photoluminescence emission of green light with a wavelength of ∼512–516 nm

  8. Using different chemical methods for deposition of copper selenide thin films and comparison of their characterization.

    Science.gov (United States)

    Güzeldir, Betül; Sağlam, Mustafa

    2015-11-01

    Different chemical methods such as Successive Ionic Layer Adsorption and Reaction (SILAR), spin coating and spray pyrolysis methods were used to deposite of copper selenide thin films on the glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) spectroscopy and UV-vis spectrophotometry. The XRD and SEM studies showed that all the films exhibit polycrystalline nature and crystallinity of copper selenide thin films prepared with spray pyrolysis greater than spin coating and SILAR methods. From SEM and AFM images, it was observed copper selenide films were uniform on the glass substrates without any visible cracks or pores. The EDX spectra showed that the expected elements exist in the thin films. Optical absorption studies showed that the band gaps of copper selenide thin films were in the range 2.84-2.93 eV depending on different chemical methods. The refractive index (n), optical static and high frequency dielectric constants (ε0, ε∞) values were calculated by using the energy bandgap values for each deposition method. The obtained results from different chemical methods revealed that the spray pyrolysis technique is the best chemical deposition method to fabricate copper selenide thin films. This absolute advantage was lead to play key roles on performance and efficiency electrochromic and photovoltaic devices. PMID:26037495

  9. A magnetic x-ray diffraction investigation of gadolinium selenide

    Energy Technology Data Exchange (ETDEWEB)

    Costa, M.M.R.; Almeida, M.J.M. de [Departamento de Fisica, Universidade de Coimbra, Coimbra (Portugal); Nuttall, W.J.; Stirling, W.G. [Department of Physics, Keele University, Keele, Staffs (United Kingdom); Tang, C.C. [Daresbury Laboratory, Warrington, Cheshire (United Kingdom); Forsyth, J.B. [Rutherford Appleton Laboratory, Chilton, Oxon (United Kingdom); Cooper, M.J. [Department of Physics, University of Warwick, Coventry (United Kingdom)

    1996-04-01

    A single-crystal synchrotron radiation study of gadolinium selenide has been made in the temperature range 15-100 K. GdSe has the rocksalt structure and becomes antiferromagnetic below a reported Neel temperature of 65 K. At 15 K, magnetic reflections are observed at G+T with modulation wavevector T={l_brace}1/2:1/2:1/2{r_brace} propagating from reciprocal lattice point G. This is achieved by exploiting the resonant enhancement in the vicinity of the Gd L{sub II} and L{sub III} edges. Similar enhancements are observed at the two edges, with the maximum effect occurring approximately 3 eV above the absorption edge. The temperature dependence of the intensity of the magnetic reflections indicates a Neel temperature of 63(1) K. These measurements, together with high-resolution studies of the fundamental reflections (T=0), contribute further evidence of magnetic or structural changes in the sample at 37(1) K. Our observations are discussed and compared with previous x-ray diffraction and magnetic susceptibility measurements. (author)

  10. Groundwater contaminant by hexavalent chromium

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C. [Univ. of Texas, Austin, TX (United States)

    1995-11-01

    Oxidation of trivalent chromium to hexavalent chromium has been investigated as a function of total manganese in soils as well as various incubation conditions. Chromium and manganese contents were analyzed by atomic absorption (graphite furnace and flame emission respectively) following acid digestion. Total hexavalent chromium generation capacity was determined by addition of 0.001 M CrCL3, incubation, and analysis by s-diphenyl carbazide. Samples were then leached with CaSO{sub 4} and MgSO{sub 4} and incubated in various environments (oven, freeze-drier, field moist, ultrafreeze) to test for geogenic generation of Cr(IV). The degree of geogenic generation of hexavalent chromium was compared with total Mn and Cr content as well as hexavalent generational capacity.

  11. Role of paramagnetic chromium in chromium(VI)-induced damage in cultured mammalian cells.

    OpenAIRE

    Sugiyama, M

    1994-01-01

    Chromium(VI) compounds are known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to chromium(III), the formation of paramagnetic chromium such as chromium(V) and chromium(III) is believed to play a role in the adverse biological effects of chromium(VI) compounds. The present report, uses electron spin resonance (ESR) spectroscopy; the importance of the role of paramagnetic chromium in chromium(VI)-induced damage in intac...

  12. Atomic force microscopy study of thermal stability of silver selenide thin films grown on silicon

    International Nuclear Information System (INIS)

    Silver selenide thin films were grown on silicon substrates by the solid-state reaction of sequentially deposited Se and Ag films of suitable thickness. Transmission electron microscopy and particle-induced X-ray emission studies of the as-deposited films showed the formation of single phase polycrystalline silver selenide from the reaction of Ag and Se films. Atomic force microscopy images of the as-deposited and films annealed at different temperatures in argon showed the film morphology to evolve into an agglomerated state with annealing temperature. The results indicate that when annealed above 473 K, silver selenide films on silicon become unstable and agglomerate through holes generated at grain boundaries

  13. Two-dimensional tin selenide nanostructures for flexible all-solid-state supercapacitors.

    Science.gov (United States)

    Zhang, Chunli; Yin, Huanhuan; Han, Min; Dai, Zhihui; Pang, Huan; Zheng, Yulin; Lan, Ya-Qian; Bao, Jianchun; Zhu, Jianmin

    2014-04-22

    Due to their unique electronic and optoelectronic properties, tin selenide nanostructures show great promise for applications in energy storage and photovoltaic devices. Despite the great progress that has been achieved, the phase-controlled synthesis of two-dimensional (2D) tin selenide nanostructures remains a challenge, and their use in supercapacitors has not been explored. In this paper, 2D tin selenide nanostructures, including pure SnSe2 nanodisks (NDs), mixed-phase SnSe-SnSe2 NDs, and pure SnSe nanosheets (NSs), have been synthesized by reacting SnCl2 and trioctylphosphine (TOP)-Se with borane-tert-butylamine complex (BTBC) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone. Utilizing the interplay of TOP and BTBC and changing only the amount of BTBC, the phase-controlled synthesis of 2D tin selenide nanostructures is realized for the first time. Phase-dependent pseudocapacitive behavior is observed for the resulting 2D nanostructures. The specific capacitances of pure SnSe2 NDs (168 F g(-1)) and SnSe NSs (228 F g(-1)) are much higher than those of other reported materials (e.g., graphene-Mn3O4 nanorods and TiN mesoporous spheres); thus, these tin selenide materials were used to fabricate flexible, all-solid-state supercapacitors. Devices fabricated with these two tin selenide materials exhibited high areal capacitances, good cycling stabilities, excellent flexibilities, and desirable mechanical stabilities, which were comparable to or better than those reported recently for other solid-state devices based on graphene and 3D GeSe2 nanostructures. Additionally, the rate capability of the SnSe2 NDs device was much better than that of the SnSe NS device, indicating that SnSe2 NDs are promising active materials for use in high-performance, flexible, all-solid-state supercapacitors. PMID:24601530

  14. Effect of He+ irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    International Nuclear Information System (INIS)

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He+ ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He+. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  15. Spray pyrolysis deposited tin selenide thin films for thermoelectric applications

    International Nuclear Information System (INIS)

    Tin selenide thin films were prepared by spray pyrolysis technique using tin (II) chloride and selenourea as a precursor compounds using Se:Sn atomic ratio of 1:1 in the starting solution onto glass substrates. Deposition process was carried out in the substrate temperature range of 250 °C–400 °C using 1 ml/min flow rate. The films were investigated using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, optical absorption and thermoelectric studies. The X-ray diffraction patterns suggest that the major phase is hexagonal-SnSe2 was present when the deposition was carried out in 275–375 °C temperature range, while for the films deposited in the below and above to this range, Sn and Se precipitates into some impure and mixed phase. Raman scattering analysis allowed the assignment of peaks at ∼180 cm−1 to the hexagonal-SnSe2 phase. The optical absorption study shows that the direct band gap of the film decreases with increase in substrate temperature and increasing crystallite size. The thermo-electrical measurements have shown n-type conductivity in as deposited films and the magnitude of thermo EMF for films has been found to be increasing with increasing deposition temperature, except for 350 °C sample. 350 °C deposited samples shows enhance thermoelectric value as compared to other samples. Thermoelectric study reveal that although sample deposited between 275 °C and 375 °C are structurally same but 350 °C sample is thermoelectrically best. - Highlights: • Influence of substrate temperature on the deposition of SnSe has been shown. • Seebeck measurements at 275°C–375 °C confirms n-type conductivity. • Higher seebeck coefficient has been observed at 350 °C deposited film. • Decrease in band gap was observed on increasing Tsub and size of the crystallites

  16. Photoconductivity in reactively evaporated copper indium selenide thin films

    International Nuclear Information System (INIS)

    Copper indium selenide thin films of composition CuInSe2 with thickness of the order of 130 nm are deposited on glass substrate at a temperature of 423 ±5 K and pressure of 10−5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%), Indium (99.999%) and Selenium (99.99%) as the elemental starting materials. X-ray diffraction (XRD) studies shows that the films are polycrystalline in nature having preferred orientation of grains along the (112) plane. The structural type of the film is found to be tetragonal with particle size of the order of 32 nm. The structural parameters such as lattice constant, particle size, dislocation density, number of crystallites per unit area and strain in the film are also evaluated. The surface morphology of CuInSe2 films are studied using 2D and 3D atomic force microscopy to estimate the grain size and surface roughness respectively. Analysis of the absorption spectrum of the film recorded using UV-Vis-NIR Spectrophotometer in the wavelength range from 2500 nm to cutoff revealed that the film possess a direct allowed transition with a band gap of 1.05 eV and a high value of absorption coefficient (α) of 106 cm−1 at 570 nm. Photoconductivity at room temperature is measured after illuminating the film with an FSH lamp (82 V, 300 W). Optical absorption studies in conjunction with the good photoconductivity of the prepared p-type CuInSe2 thin films indicate its suitability in photovoltaic applications

  17. Fate and transport of chromium through soil

    International Nuclear Information System (INIS)

    Chromium chemistry relevant to the problem facing state of New Jersey (Usa) was examined. Transport of chromium through soil depends on its chemical forms. Transformation of chromium within bulk of soil depends on soil constituents, soil condition, such as pH, Eh and organic compounds applied onto soil or present in soil. Total chromium in soil can be determined. Speciation of chromium based on ionization, hydrolysis, complex formation, redox reactions and adsorption is predicted using MINIQ program

  18. Release of Chromium from Orthopaedic Arthroplasties

    OpenAIRE

    Afolaranmi, G.A.; Tettey, J; Meek, R.M.D; Grant, M.H

    2008-01-01

    Many orthopaedic implants are composed of alloys containing chromium. Of particular relevance is the increasing number of Cobalt Chromium bearing arthroplasies being inserted into young patients with osteoarthritis. Such implants will release chromium ions. These patients will be exposed to the released chromium for over 50 years in some cases. The subsequent chromium ion metabolism and redistribution in fluid and tissue compartments is complex. In addition, the potential biological effects o...

  19. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

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

  20. Chromium reduction in Pseudomonas putida.

    OpenAIRE

    Ishibashi, Y.; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.

  1. Chromium reduction in Pseudomonas putida.

    Science.gov (United States)

    Ishibashi, Y; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells. PMID:2389940

  2. Polystyrene-supported Selenides and Selenoxide:Versatile Routes to Synthesize Allylic Alcohols

    Institute of Scientific and Technical Information of China (English)

    Wei Ming XU; You Chu ZHANG; Xian HUANG

    2003-01-01

    Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.

  3. Effect of sulfur doping on thermoelectric properties of tin selenide – A first principles study

    International Nuclear Information System (INIS)

    In this work we present the thermoelectric properties of tin selenide (SnSe) and sulfur doped tin selenide(SnSe(1-x)Sx, x= 0.125 and 0.25) obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BOLTZTRAP code using the constant relaxation time approximation at three different temperatures 300, 600 and 800 K. Seebeck coefficient (S) was found to decrease with increasing temperature, electrical conductivity (σ/τ) was almost constant in the entire temperature range and thermal conductivity (κ/τ) increased with increasing temperature for all samples. Sulfur doped samples showed enhanced seebeck coefficient, decreased thermal conductivity and decreased electrical conductivity at all temperatures. At 300 K, S increased from 1500 µV/K(SnSe) to 1720μV/K(SnSe0.75S0.25), thermal conductivity decreased from 5 × 1015 W/mKs(SnSe) to 3 × 1015 W/mKs(SnSe0.75S0.25), electrical conductivity decreased from 7 × 1020/Ωms(SnSe) to 5 × 1020 /Ωms(SnSe0.75S0.25). These calculations show that sulfur doped tin selenide exhibit better thermoelectric properties than undoped tin selenide

  4. Formation of Silver Selenide Layers on Polyamide 6 Films by the Use of Potassium Selenotrithionate

    Directory of Open Access Journals (Sweden)

    Remigijus IVANAUSKAS

    2011-11-01

    Full Text Available A polyamide 6 films if treated with the potassium selenotrithionate, K2SeS2O6, solution in hydrochloric acid, absorbs selenium the form of selenotrithionate anion, SeS2O62-, and the anions decompose in polymer with time. Further interaction of selenized PA films with AgNO3 solution (10 min, 80 °C leads to the formation of silver selenide layers on the polymer surface. The mechanism of formation of silver selenide layers on PA 6 films was proposed. The chemical analyzes show that the concentrations of silver and selenium in polyamide 6 film increase when increase the duration of polymer seleniumization. The molar ratio of Ag/Se in the layers of silver selenide on polyamide films varied from 0.57 : 1 to 0.7 : 1. The X-ray diffraction analysis confirmed the formation of silver selenide layers with elemental selenium in the surface of polyamide 6. The phases of orthorhombic naumannite - Ag2Se (24-1041 and monoclinic selenium - Se8 (71-528 were identified in the formed layers.http://dx.doi.org/10.5755/j01.ms.17.4.775

  5. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    International Nuclear Information System (INIS)

    Highlights: ► Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ► The fabricated white LEDs show good white balance. ► CdSe QDs present well green to yellow band luminescence. ► CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors

  6. The bulk modulus of cubic spinel selenides: an experimental and theoretical study

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, Leif; Olsen, J.S.;

    2009-01-01

    It is argued that mainly the selenium sublattice determines the overall compressibility of the cubic spinel selenides, AB2Se4, and that the bulk modulus for these compounds is about 100GPa. The hypothesis is supported by experiments using high-pressure X-ray diffraction and synchrotron radiation...

  7. Spray pyrolysis deposited tin selenide thin films for thermoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Anwar, Sharmistha; Gowthamaraju, S.; Mishra, B.K.; Singh, S.K.; Shahid, Anwar, E-mail: shahidanwr@gmail.com

    2015-03-01

    Tin selenide thin films were prepared by spray pyrolysis technique using tin (II) chloride and selenourea as a precursor compounds using Se:Sn atomic ratio of 1:1 in the starting solution onto glass substrates. Deposition process was carried out in the substrate temperature range of 250 °C–400 °C using 1 ml/min flow rate. The films were investigated using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, optical absorption and thermoelectric studies. The X-ray diffraction patterns suggest that the major phase is hexagonal-SnSe{sub 2} was present when the deposition was carried out in 275–375 °C temperature range, while for the films deposited in the below and above to this range, Sn and Se precipitates into some impure and mixed phase. Raman scattering analysis allowed the assignment of peaks at ∼180 cm{sup −1} to the hexagonal-SnSe{sub 2} phase. The optical absorption study shows that the direct band gap of the film decreases with increase in substrate temperature and increasing crystallite size. The thermo-electrical measurements have shown n-type conductivity in as deposited films and the magnitude of thermo EMF for films has been found to be increasing with increasing deposition temperature, except for 350 °C sample. 350 °C deposited samples shows enhance thermoelectric value as compared to other samples. Thermoelectric study reveal that although sample deposited between 275 °C and 375 °C are structurally same but 350 °C sample is thermoelectrically best. - Highlights: • Influence of substrate temperature on the deposition of SnSe has been shown. • Seebeck measurements at 275°C–375 °C confirms n-type conductivity. • Higher seebeck coefficient has been observed at 350 °C deposited film. • Decrease in band gap was observed on increasing Tsub and size of the crystallites.

  8. Formation of Cadmium Selenide Layers on the Polyamide Film Surface by Sorption-Diffusion Method

    Directory of Open Access Journals (Sweden)

    Neringa Petrašauskienė

    2015-03-01

    Full Text Available The layers containing cadmium selenide, CdxSe,were formed on the surface of semihydrophilic polymer – polyamide 6 (PA using acidified 0.10 mol/dm3 solution of potassium selenotrithionate, K2SeS2O6,as precursor of selenium. The concentration of sorbed selenium (at 60 oC increases with the increase of the duration of PA treatment in K2SeS2O6solution. The cadmium selenide containing layers are formed on the surface of PA after the treatment of seleniumized polymer with cadmium acetate, (Cd(CH3COO2·2H2O, solution (60–80 oC:the anions SeS2O62– containing selenium atoms of low oxidation state react with the cadmium(II ions. The conditions of a polymer initial seleniumization and of seleniumized PA treatment with cadmium acetate solution determine the concentration of cadmium and the composition of chalcogenide layer. The concentration of cadmium in the chalcogenide layer increases with the increase of initial chalcogenization duration only up to about 2 h and the temperature of selenotrithionate solution. The results of XPS and XRD confirmed the formation of cadmium selenide layers on the surface of PA. XRD patterns study of not earlier studied CdSe layers on PA showed their phase composition of two cadmium selenides phases – Zinc blende (cubic CdSe,wurtzite (hexagonal CdSe and cadmium(II hydroxide, Cd(OH2. Accordingly data of XRD and XPS analysis the macrostructure and composition ofCuSe layers depends on the conditions of these layers formation. The data determined enable formation of the layers of cadmium selenide on the surface of PA by thesorption-diffusion method using the solution of potassium selenotrithionate as a precursor of selenium.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5097

  9. Hydrogen permeation through chromium

    International Nuclear Information System (INIS)

    Steady state and non-steady state measurements of hydrogen permeation through metallic chromium are reported. The experiments have been conducted by use of hydrogen and deuterium within a pressure range of 10-8 - 1 bar and temperatures between 600 - 8000C. Numerical values for the physical quantities permeability, diffusion constant and solubility could be derived. At an upstream pressure above around 10-3 bar classical Sieverts-low was found (permeation rate proportional √p) with activation energies Qsub(perm) = 65 kJoule/mole, Qsub(Diff) = 4-8 kJoule/mole, Qsub(Sol) = 57-61 kJoule/mole for the respective processes involved. The isotopic effect between H and D of the permeabilities could be represented by a factor of 1,5 independence on temperature. All non steady-state measurements could be approximated reasonably well by classical diffusion kinetics. Below up-stream pressures of approx.= 10-7 bar the kinetics was no longer diffusion controlled, the dependence on up-stream pressure changed from √p -> p, the activation energy for permetation increased to 127 kJoule/mole and the isotopic factor resulted in about 2-3. (orig.)

  10. Trivalent chromium sorption on alginate beads

    OpenAIRE

    Araújo, M. Manuela; Teixeira, J.A.

    1997-01-01

    The applicability of trivalent chromium removal from aqueous solutions using calcium alginate beads was studied. The equilibrium isotherms were plotted at two temperatures. The relationship between the chromium sorbed and the calcium released was determined as well as the effect of alginate amount and initial pH on the equilibrium results. Chromium sorption kinetics were evaluated as a function of chromium initial concentration and temperature. Transport properties of trival...

  11. On texture formation of chromium electrodeposits

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Leisner, Peter; Horsewell, Andy

    1998-01-01

    The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been...

  12. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

    Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.; Gilheany, Declan G.

    2002-01-01

    The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall, the......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

  13. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    International Nuclear Information System (INIS)

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2-xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells

  14. Functional metal sulfides and selenides for the removal of hazardous dyes from Water.

    Science.gov (United States)

    Shamraiz, Umair; Hussain, Raja Azadar; Badshah, Amin; Raza, Bareera; Saba, Sonia

    2016-06-01

    Water contamination by organic dyes, is among the most alarming threats to healthy green environment. Complete removal of organic dyes is necessary to make water healthy for drinking, cooking, and for other useful aspects. Recently use of nanotechnology for removing organic dyes, became fruitful because of high surface to volume ratio and adsorption properties. Among these materials, metal chalcogenides emerge as new class of active materials for water purification. In this review article, we gathered information related to sulfide and selenide based nanomaterials which include metal sulfides and selenides, their binary composites, and use of different capping agents and dopants for enhancing photocatalysis. We have discussed in detail, about adsorption power of different dyes, relative percentage degradation, reaction time and concentration. PMID:27010842

  15. Chromium content of selected Greek foods.

    Science.gov (United States)

    Bratakos, Michael S; Lazos, Evangelos S; Bratakos, Sotirios M

    2002-05-01

    The total chromium content of a wide variety of Greek foods was determined by graphite furnace atomic absorption spectroscopy (GFAAS). Meat, fish and seafood, cereals and pulses were rich sources of chromium (>0.100 microg/g). Fruits, milk, oils and fats and sugar were poor sources. Differences in chromium content were found between different food classes from Greece and those from some other countries. Based on available food consumption data and chromium levels in this study, it was estimated that the chromium intake of Greeks is 143 microg/day, with vegetables, cereals and meat being the main contributors. PMID:12083715

  16. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    OpenAIRE

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M.

    2015-01-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, ...

  17. Enhancement of thermoelectric figure-of-merit by resonant states of aluminium doping in lead selenide

    OpenAIRE

    Zhang, Qinyong; Wang, Hui; Liu, Weishu; Wang, Hengzhi; Yu, Bo; Zhang, Qian; Tian, Zhiting; Lee, Sangyeop; Esfarjani, Keivan; Chen, Gang; Ren, Zhifeng; Ni, George Wei

    2011-01-01

    By adding aluminium (Al) into lead selenide (PbSe), we successfully prepared n-type PbSe thermoelectric materials with a figure-of-merit (ZT) of 1.3 at 850 K. Such a high ZT is achieved by a combination of high Seebeck coefficient caused by very possibly the resonant states in the conduction band created by Al dopant and low thermal conductivity from nanosized phonon scattering centers.

  18. Lattice Dynamics at Zone-Center of Sulphide and Selenide Spinels

    Institute of Scientific and Technical Information of China (English)

    A.K. Kushwaha

    2008-01-01

    A rigid-ion model is used to calculate the force constants and effective dynamical charges of sulphide and selenide spinels. The Raman and infrared phonon modes of normal cubic sulphide spinels MCr2S4 (M=Mn, Co, Fe, Hg, Zn, and Cd) and selenide spinels MCr2Se4 (M=Hg, Zn, and Cd) are calculated at the first Brillouin zone-centre using above model. The significant outcome of the present work is (I) the interatomic interaction between Cr-S (Se) dominates over the Cr-S(Se) and S-S(Se-Se) type of interatomic interactions, (ii) the effective dynamical charges of the bivalent metal ions are nearly zero, and (ⅲ) the selenide spinels are less ionic than the sulphide spinels and the ionicity decreases as MnCr2S4 FeCr2S4 CoCr2S4 > and CdCr2C4 > ZnCr2C4 > HgCr2C4 (C=S and Se). The zone-center phonon frequencies, calculated using these parameters, are found to be in very good agreement with the observed results.

  19. Determination of chromium combined with DNA, RNA and protein in chromium-rich brewer's yeast

    International Nuclear Information System (INIS)

    The contents of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast were determined with the neutron activation analysis in order to study the combination of Cr with DNA, RNA and protein in chromium-rich brewer's yeast. The results showed that the extracting rats and concentrations of DNA, RNA and protein had no significant difference in two types of yeast, but the chromium contents of DNA, RNA and protein in the chromium-rich yeast were significantly higher than those in the normal. In addition, the content of chromium in DNA was much higher than that in RNA and protein, which indicated that the inorganic chromium compounds entered into the yeast cell, during the yeast cultivation in the culture medium containing chromium were converted into organic chromium compounds combined with DNA, RNA and protein

  20. Tissues and urinary chromium concentrations in rats fed high-chromium diets

    International Nuclear Information System (INIS)

    Complete text of publication follows. Chromium is an essential trace elements and enhances the function of insulin as a form of chromodulin. In the subjects with a certain type of diabetics, 200 to 1,000 μg/d of chromium is administered to reduced the symptoms of diabetics. However, although there are not any health-promotive effects of chromium-administration in healthy subjects, various types of chromium supplements are commercially available in many countries; the adverse effects caused by an excessive chromium intake are feared. In the present study, to clarify the tolerable upper limit of chromium, tissue and urinary chromium concentrations, liver function and iron status were examined in rats fed high-chromium diets. Thirty-six male 4-weeks Wistar rats were divided into six groups and fed casein-based diets containing 1, 10 or 100 μg/g of chromium as chromium chloride (CrCl3) or chromium picolinate (CrPic) for 4 weeks. After the feeding, chromium concentrations in liver, kidney, small intestine and tibia were determined by inductively coupled plasma-mass spectrometry. In addition, urine samples were collected on 3rd to 4th week and their chromium concentrations were also determined. Chromium concentrations in liver, kidney, small intestine and tibia were elevated with increase of dietary chromium concentration. Urinary chromium excretion was also elevated with the increase of dietary chromium and the rate of urinary chromium excretion was less than 2% to dietary chromium intake in all the experimental groups. In the administration of 100 μg/g of chromium, rats given CrCl3 showed significantly higher tibia chromium concentration and lower urinary chromium excretion than those given CrPic. There were not any differences in iron status among the experimental groups. Activities of serum aspartate aminotransferase and alanine aminotransferase in rats fed diet containing 100 μg/g of chromium as CrPic were significantly higher than those in rats fed other diets.

  1. Food Chromium Contents, Chromium Dietary Intakes And Related Biological Variables In French Free-Living Elderly

    Science.gov (United States)

    Chromium (Cr III), an essential trace element, functions in potentiating insulin sensitivity, regulating glucose homeostasis, improving lipid profile, and maintaining lean body mass. Glucose intolerance and chromium deficiency increase with age, and could be aggravating factors of the metabolic synd...

  2. Soils contaminated with hexavalent chromium

    OpenAIRE

    Fonseca, Bruna Catarina da Silva

    2011-01-01

    Tese de doutoramento em Engenharia Química e Biológica The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. With this in mind, and because chromium and lead are two of the most toxic heavy metals frequently detected as soil contaminants in the Portuguese territory, the study and development of few remediation techniques and the indissociable description of the sorption and migration of...

  3. Carbon, chromium and molybdenum contents

    International Nuclear Information System (INIS)

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite

  4. Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

    OpenAIRE

    V. S. Protsenko; V. O Gordiienko; Danilov, F. I.; Kwon, S.C.

    2011-01-01

    A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40 oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

  5. REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

    OpenAIRE

    A. R. Asgari ، F. Vaezi ، S. Nasseri ، O. Dördelmann ، A. H. Mahvi ، E. Dehghani Fard

    2008-01-01

    Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide. It was found that granular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from ...

  6. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  7. Inoculation of chromium white cast iron

    OpenAIRE

    D. Kopyciński

    2009-01-01

    It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  8. Selenide and telluride glasses for mid-infrared bio-sensing

    Science.gov (United States)

    Cui, Shuo; Chahal, Radwan; Shpotyuk, Yaroslav; Boussard, Catherine; Lucas, Jacques; Charpentier, Frederic; Tariel, Hugues; Loréal, Olivier; Nazabal, Virginie; Sire, Olivier; Monbet, Valérie; Yang, Zhiyong; Lucas, Pierre; Bureau, Bruno

    2014-02-01

    Fiber Evanescent Wave Spectroscopy (FEWS) is an efficient way to collect optical spectra in situ, in real time and even, hopefully, in vivo. Thanks to selenide glass fibers, it is possible to get such spectra over the whole mid-infrared range from 2 to 12 μm. This working window gives access to the fundamental vibration band of most of biological molecules. Moreover selenide glasses are stable and easy to handle, and it is possible to shape the fiber and create a tapered sensing head to drastically increase the sensitivity. Within the past decades, numerous multi-disciplinary studies have been conducted in collaboration with the City Hospital of Rennes. Clinical trials have provided very promising results in biology and medicine which have led to the creation in 2011 of the DIAFIR Company dedicated to the commercialization of fiber-based infrared biosensors. In addition, new glasses based on tellurium only have been recently developed, initially in the framework of the Darwin mission led by the European Space Agency (ESA). These glasses transmit light further into the far-infrared and could also be very useful for medical applications in the near future. Indeed, they permit to reach the vibrational bands of biomolecules laying from 12 to 16 μm where selenide glasses do not transmit light anymore. However, while Se is a very good glass former, telluride glasses tend to crystallize easily due to the metallic nature of Te bonds. Hence, further work is under way to stabilize the glass composition for fibers drawing and to lower the optical losses for improving their sensitivity as bio-sensors.

  9. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C;

    1992-01-01

    of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...... barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration...... indicating a limited reduction ability of the skin in vitro....

  10. Effect of He{sup +} irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh Kumar, M.C., E-mail: santhoshmc@yahoo.co [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620 015 (India); Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India)

    2010-04-09

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He{sup +} ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He{sup +}. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  11. TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

    International Nuclear Information System (INIS)

    Highlights: • Ag2Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag2Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag2Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphine (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag2Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag2Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the structure of the PVP/Ag2Se

  12. TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

    Energy Technology Data Exchange (ETDEWEB)

    More, D.S. [Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Moloto, M.J., E-mail: makwenam@vut.ac.za [Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Moloto, N. [School of Chemistry, Faculty of Science, University of the Witwatersrand, Private Bag 3, Johannesburg 2050 (South Africa); Matabola, K.P. [Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 South Africa (South Africa)

    2015-05-15

    Highlights: • Ag{sub 2}Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag{sub 2}Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag{sub 2}Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphine (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag{sub 2}Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag{sub 2}Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the

  13. Analysis on the Performance of Copper Indium Gallium Selenide (CIGS) Based Photovoltaic Thermal

    OpenAIRE

    Zulkepli Afzam; Yong Lim Wei; Taib Mohd Yusof; Azran Zafri; Basrawi Firdaus

    2016-01-01

    This paper deals with the efficiency improvement of Copper Indium Gallium Selenide (CIGS) Photovoltaic (PV) and also solar thermal collector. Photovoltaic thermal (PV/T) can improve overall efficiency for PV and also solve the problem of limited roof space at urban area. Objective of this study is to clarify the effect of mass flow rate on the efficiency of the PV/T system. A CIGS solar cell is used with rated output power 65 W and 1.18 m2 of area. 4 set of experiments were carried out, which...

  14. Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

    KAUST Repository

    Lee, Kyu-Sung

    2011-12-01

    We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

  15. Polarity and structure peculiarities of trialkylphosphine oxides, sulfides, selenides and tellurides

    International Nuclear Information System (INIS)

    Using the quantum-chemical calculations structural characteristics of trialkylphosphine oxides, sulfates, selenides and tellurides (Alk3P=X; X O, S, Se, Te) are obtained, which are in good agreement with literature X-ray structural analysis and gas-phase electron diffraction data. The P=X bonds polarity is determined in the framework of vector-additive scheme on the base of experimental data on components dipole moments and using different base series of molecules geometry parameters. It is shown that increasing of bond moment P=X in the X = O, S, Se, Te series takes place through dipole length increasing

  16. Structural, optical and electrical properties of chemically deposited copper selenide films

    Indian Academy of Sciences (India)

    R H Bari; V Ganesan; S Potadar; L A Patil

    2009-02-01

    Stoichiometric and nonstoichiometric thin films of copper selenide have been prepared by chemical bath deposition technique at temperature below 60°C on glass substrate. The effect of nonstoichiometry on the optical, electrical and structural properties of the film was studied. The bandgap energy was observed to increase with the increase in at % of copper in composition. The grain size was also observed to increase with the decrease of at % of copper in composition. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), absorption spectroscopy, and AFM. The results are discussed and interpreted.

  17. Solution-Liquid-Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst.

    Science.gov (United States)

    Xu, Kun; Ding, Hui; Jia, Kaicheng; Lu, Xiuli; Chen, Pengzuo; Zhou, Tianpei; Cheng, Han; Liu, Si; Wu, Changzheng; Xie, Yi

    2016-01-26

    Inorganic nanowire arrays hold great promise for next-generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution-liquid-solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low-temperature solution synthesis. As a proof-of-concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires. PMID:26695560

  18. Electrical properties of silver selenide thin films prepared by reactive evaporation

    Indian Academy of Sciences (India)

    M C Santhosh Kumar; B Pradeep

    2002-10-01

    The electrical properties of silver selenide thin films prepared by reactive evaporation have been studied. Samples show a polymorphic phase transition at a temperature of 403 ± 2 K. Hall effect study shows that it has a mobility of 2000 cm2V–1s–1 and carrier concentration of 1018 cm–3 at room temperature. The carriers are of -type. X-ray diffraction study indicates that the as-prepared films are polycrystalline in nature. The lattice parameters were found to be = 4.353 Å, = 6.929 Å and = 7.805 Å.

  19. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    This study was undertaken to determine if chromium(+6) could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium(+3) to chromium(+6) by nitric acid; and the reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium(+3) to chromium(+6) was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the (+6) oxidation state and would not exist in the (+6) state in the final process waste solutions

  20. Alkane dehydrogenation over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The dehydrogenation of alkanes over supported chromium oxide catalysts in the absence of oxygen is of high interest for the industrial production of propene and isobutene. In this review, a critical overview is given of the current knowledge nowadays available about chromium-based dehydrogenation ca

  1. Compatibility of Pt-3008 with selected components of the selenide isotope generator system

    International Nuclear Information System (INIS)

    The first in a new generation of radioisotopic thermoelectric generators being built by Teledyne Energy Systems and designated the Selenide Isotope Generator has thermoelectric materials that can be degraded by reaction with O2, H2O, CO, and other gases. Consequently, for at least the first ground demonstration system a protective xenon atmosphere will be maintained over the thermoelectrics. The high-temperature portion of the atmosphere-retaining structure will be fabricated from the alloy Pt-3008 (Pt--30 wt % Rh--8 wt % W), which was developed at Oak Ridge National Laboratory. For this application Pt-3008 must be compatible with the various insulations and thermoelectric materials. A study of the compatibility of Pt-3008 with these materials and showed that Pt-3008 was embrittled after exposure to some of the insulations that were not adequately outgassed and by one of the thermoelectric materials (Cu2Se) in some of the isothermal tests. It is believed that Pt-3008 will be compatible with the Selenide Isotope Generator materials when they are well outgassed and under the temperature gradient conditions of the operating system

  2. Asymmetric supercapacitors with metal-like ternary selenides and porous graphene electrodes

    KAUST Repository

    Xia, Chuan

    2016-04-14

    Asymmetric supercapacitors provide a promising approach to fabricate capacitive energy storage devices with high energy and power densities. In this work, asymmetric supercapacitors with excellent performance have been fabricated using ternary (Ni, Co)0.85Se on carbon fabric as bind-free positive electrode and porous free-standing graphene films as negative electrode. Owing to their metal-like conductivity (~1.67×106 S m−1), significant electrochemical activity, and superhydrophilic nature, our nanostructured ternary nickel cobalt selenides result in a much higher areal capacitance (2.33 F cm−2 at 4 mA cm−2), better rate performance and cycling stability than their binary selenide equivalents, and other ternary oxides and chalcogenides. Those hybrid supercapacitors can afford impressive areal capacitance and stack capacitance of 529.3 mF cm−2 and 6330 mF cm−3 at 1 mA cm−2, respectively. More impressively, our optimized asymmetric device operating at 1.8 V delivers a very high stack energy density of 2.85 mWh cm−3 at a stack power density of 10.76 mW cm−3, as well as 85% capacitance retention after 10,000 continuous charge-discharge cycles. Even at a high stack power density of 1173 mW cm−3, this device still deliveries a stack energy density of 1.19 mWh cm−3, superior to most of the reported supercapacitors.

  3. Photoluminescence of Nitrogen-Doped Zinc Selenide by Photo-Assisted Mocvd.

    Science.gov (United States)

    Gillespie, Paul Matthew

    Zinc selenide is a wide band-gap (2.67 eV) II -VI compound semiconductor with potential use as a blue electro-optic device material. Problems with obtaining suitable p-type conductivity have limited device development. Zinc selenide epitaxial films, doped with nitrogen from NH _3, have been grown on gallium arsenide substrates by laser-assisted metal organic chemical vapor deposition (MOCVD). The effect of nitrogen doping was investigated with and without direct surface irradiation incident on the surface from a broad-band light source. Low temperature (8 K) photoluminescence spectroscopy has confirmed the incorporation of nitrogen as a shallow acceptor by the presence of acceptor-bound-excitons and associated donor -acceptor-pair recombination emissions. The MOCVD growth parameters have been optimized based on the presence of characteristic features in the photoluminescence spectra. Growth rate mechanisms have been proposed for both laser-assisted MOCVD and direct-irradiation MOCVD. Simultaneous interaction of the two photo-assisted techniques show that direct irradiation of the surface does not enhance the growth rate under the laser-assisted condition. This confirms that direct surface irradiation growth mechanisms involve the interaction of photo-generated carriers with alkyl groups from the precursors.

  4. Transparent metal selenide alloy counter electrodes for high-efficiency bifacial dye-sensitized solar cells.

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; Liu, Juan; He, Benlin; Yu, Liangmin

    2014-12-22

    The exploration of cost-effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye-sensitized solar cells (DSSCs). Transparent counter electrodes based on binary-alloy metal selenides (M-Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution-based method and employed in efficient bifacial DSSCs. Owing to superior charge-transfer ability for the I(-) /I3 (-) redox couple, electrocatalytic activity toward I3 (-) reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30 % and 4.63 % for Co0.85 Se, 7.85 % and 4.37 % for Ni0.85 Se, 6.43 % and 4.24 % for Cu0.50 Se, 7.64 % and 5.05 % for FeSe, and 9.22 % and 5.90 % for Ru0.33 Se in comparison with 6.18 % and 3.56 % for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels. PMID:25358619

  5. From zinc selenate to zinc selenide nano structures synthesized by reduction process

    International Nuclear Information System (INIS)

    One-dimensional nano structure materials are very attractive because of their electronic and optical properties depending on their size. It is well known that properties of material can be tuned by reducing size to nano scale because at the small sizes, that they behave differently with its bulk materials and the band gap will control by the size. The tunability of the band gap makes nano structured materials useful for many applications. As one of the wide band gaps semiconductor compounds, zinc selenide (ZnSe) nano structures (nanoparticles, nano wires, nano rods) have received much attention for the application in optoelectronic devices, such as blue laser diode, light emitting diodes, solar cells and IR optical windows. In this study, ZnSe nano structures have been synthesized by reduction process of zinc selenate using hydrazine hydrate (N2H4.2H2O). The reductive agent of hydrazine hydrate was added to the starting materials of zinc selenate were heat treated at 500 degree Celsius for 1 hour under argon flow to form one-dimensional nano structures. The SEM and TEM images show the formation of nano composite-like structure, which some small nano bar and nano pellets stick to the rod. The x-ray diffraction and elemental composition analysis confirm the formation of mixture zinc oxide and zinc selenide phases. (author)

  6. Neutron scattering and models: Chromium

    International Nuclear Information System (INIS)

    Differential neutron elastic-scattering cross sections of elemental chromium are measured from 4.5 ∼ 10 MeV in steps of ∼ 0.5 MeV and at ≥ 40 scattering angles distributed between ∼ 17 degree--160 degree. Concurrently differential cross sections for the inelastic neutron excitation of the yrast 2+ (1.434 MeV) level in d52Cr are determined. In addition, broad inelastically-scattered neutron groups are observed corresponding to composite excitation of levels up to ∼ 5.5 MeV in the various chromium isotopes. These experimental results are combined with low-energy values previously reported from this laboratory, with recent ∼ 8 → 15 MeV data measured at the Physikalisch-Technische Bundesanstalt and with a 21.6 MeV result from the literature to form an extensive neutron-scattering data base which is interpreted in the context of spherical-optical and coupled-channels (rotational and vibrational) models. These models reasonably describe the observables but indicate rather large energy-dependent parameter trends at low energies similar to those previously reported near the peak of the So strength function in studies at this laboratory. The physical implications of the measurements and models are discussed including deformation, coupling, dispersive and asymmetry effects

  7. Methylselenol formed by spontaneous methylation of selenide is a superior selenium substrate to the thioredoxin and glutaredoxin systems.

    Directory of Open Access Journals (Sweden)

    Aristi P Fernandes

    Full Text Available Naturally occurring selenium compounds like selenite and selenodiglutathione are metabolized to selenide in plants and animals. This highly reactive form of selenium can undergo methylation and form monomethylated and multimethylated species. These redox active selenium metabolites are of particular biological and pharmacological interest since they are potent inducers of apoptosis in cancer cells. The mammalian thioredoxin and glutaredoxin systems efficiently reduce selenite and selenodiglutathione to selenide. The reactions are non-stoichiometric aerobically due to redox cycling of selenide with oxygen and thiols. Using LDI-MS, we identified that the addition of S-adenosylmethionine (SAM to the reactions formed methylselenol. This metabolite was a superior substrate to both the thioredoxin and glutaredoxin systems increasing the velocities of the nonstoichiometric redox cycles three-fold. In vitro cell experiments demonstrated that the presence of SAM increased the cytotoxicity of selenite and selenodiglutathione, which could neither be explained by altered selenium uptake nor impaired extra-cellular redox environment, previously shown to be highly important to selenite uptake and cytotoxicity. Our data suggest that selenide and SAM react spontaneously forming methylselenol, a highly nucleophilic and cytotoxic agent, with important physiological and pharmacological implications for the highly interesting anticancer effects of selenium.

  8. Chemical Stability of Chromium Carbide and Chromium Nitride Powders Compared with Chromium Metal in Synthetic Biological Solutions

    OpenAIRE

    Tao Jiang; Inger Odnevall Wallinder; Gunilla Herting

    2012-01-01

    Chromium carbide (Cr-C) and chromium nitride (Cr-N) powders were compared with a chromium metal powder (Cr-metal) to evaluate their chemical stability in solution. All three powders were exposed in five different synthetic biological solutions of varying pH and chemical composition simulating selected human exposure conditions. Characterisation of the powders, using GI-XRD, revealed that the predominant bulk crystalline phases were Cr7C3 and Cr2N for Cr-C and Cr-N respectively. The outermost ...

  9. Low-chromium reduced-activation chromium-tungsten steels

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Maziasz, P.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Bainitic microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of non-classical bainite were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was found to be considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2 1/4Cr-2W and 2 1/4Cr-2WV steel compositions to increase their hardenability, and the microstructures and mechanical properties were examined.

  10. Bainitic chromium-tungsten steels with 3 pct chromium

    International Nuclear Information System (INIS)

    Previous work on 3Cr-1.5MoV (nominally Fe-3Cr-2.5Mo-0.25V-0.1C), 2.25Cr-2W (Fe-2.25Cr-2W-0.1C), and 2.25Cr-2WV (Fe-2.25Cr-2W-0.25V-0.1C) steels indicated that the impact toughness of these steels depended on the microstructure of the bainite formed during continuous cooling from the austenization temperature. Microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of nonclassical microstructures were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2.25Cr-2W and 2.25Cr-2WV steel compositions to increase their hardenability. Charpy testing indicated that the new 3Cr-W and 3Cr-WV steels had improved impact toughness, as demonstrated by lower ductile-brittle transition temperatures and higher upper-shelf energies. This improvement occurred with less tempering than was necessary to achieve similar toughness for the 2.25Cr steels and for high-chromium (9 to 12 pct Cr) Cr-W and Cr-Mo steels

  11. Reproductive toxicological aspects of chromium in males

    International Nuclear Information System (INIS)

    To expand our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and γ-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG)

  12. Formation of Cadmium Selenide Containing Layers on the Polyamide Film Surface by the Use of Potassium Selenotrithionate

    Directory of Open Access Journals (Sweden)

    Neringa PETRASAUSKIENE

    2015-05-01

    Full Text Available The layers containing cadmium selenide, CdxSe, were formed on the surface of semi hydrophilic polymer – polyamide 6 (PA for the first time by sorption-diffusion method using acidified solution of potassium selenotrithionate, K2SeS2O6, as a precursor of selenium. The concentration of sorbed selenium increases with the increase of the duration of PA treatment in K2SeS2O6 solution. The cadmium selenide containing layers form on the surface of PA after the treatment of seleniumized polymer with cadmium acetate, Cd(CH3COO2·2H2O, solution: the anions SeS2O62– containing selenium atoms of low oxidation state react with the cadmium(II ions. The conditions of a polymer initial seleniumization and of seleniumized PA treatment with cadmium acetate solution determine the concentration of cadmium and the composition of chalcogenide layer. The concentration of cadmium in the chalcogenide layer increases with the increase of initial chalcogenization duration only up to about 2 h and the temperature of selenotrithionate solution. XRD confirmed the formation of cadmium selenide containing layers on the surface of PA. The results of XPS and XRD patterns study of not earlier studied CdSe containing layers on PA showed their phase composition of two cadmium selenide phases – zinc blende (cubic CdSe, wurtzite (hexagonal CdSe, cadmium(II oxide, CdO, and cadmium(II hydroxide, Cd(OH2. Accordingly data of XRD and XPS analysis the composition of CdSe containing layers depends on the conditions of these layers formation. The data determined enable formation of the layers containing cadmium selenide on the surface of PA by the sorption-diffusion method using the solution of potassium selenotrithionate as a precursor of selenium.

  13. Synthesis of Chromium (Ⅲ) 5-aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin

    2004-01-01

    As we all known that diabetes is a chronic disease with major health consequences.Research has revealed that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF) [1], no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr) [2] . So there is potential for the design of new chromium drugs .5-Aminosalicylic acid (5-ASA) is identified as an active component in the therapy of inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis . The therapeutic action of 5-ASA is believed to be coupled to its ability to act as a free radical scavenger [3-4],acting locally on the inflamed colonic mucosa [5-7]. However, the clinical use of 5-ASA is limited, since orally administered 5-ASA is rapidly and completely absorbed from the upper gastrointestinal tract and therefore the local therapeutic effects of 5-ASA in the colon is hardly expected.In this paper, we report the synthesis of chromium(Ⅲ)5-aminosalicylate from 5-ASA and CrCl3. 6H2O.The synthesis route is as follow:The complex has been characterized by elemental analysis, IR spectra, X-ray powder diffractionand TG-DTA . They indicate that the structure is tris(5-ASA) Chromium . Experiments show that thecomplex has a good activity for supplement tiny dietary chromium, lowering blood glucose levels,lowering serum lipid levels and in creasing lean body mass .

  14. Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B;

    2012-01-01

    Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

  15. Characteristics of chromium-allergic dermatitis patients prior to regulatory intervention for chromium in leather

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus;

    2014-01-01

    BACKGROUND: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states. OBJECTIVES: To characterize patients with...... chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather. METHODS: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched...... control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations. RESULTS: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather...

  16. Chromium intensification of a processed dental radiograph

    International Nuclear Information System (INIS)

    This study was undertaken to determine (1) the usefulness of chromium intensifier to improve the diagnostic quality of light radiograph; (2) the effect of chromium intensifier on density contrast; and (3) the effect of various chemical concentrations on density. The following results obtained: 1. CHROMIUM INTENSIFIER is useful for intensifying and improving the diagnostic quality of a light dental radiograph. 2. The degree of intensification can be controlled by varying bleaching time, repeating the processing, varying the proportions of the potassium bicarbonate and hydrochloric acid solutions. 3. The image produced is black and permanent. 4. The intensifier increases density and contrast

  17. Chromium (VI) adsorption on boehmite

    Energy Technology Data Exchange (ETDEWEB)

    Granados-Correa, F. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)], E-mail: fgc@nuclear.inin.mx; Jimenez-Becerril, J. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)

    2009-03-15

    Boehmite was synthesized and characterized in order to study the adsorption behavior and the removal of Cr(VI) ions from aqueous solutions as a function of contact time, initial pH solution, amount of adsorbent and initial metal ion concentration, using batch technique. Adsorption data of Cr(VI) on the boehmite were analyzed according to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption models. Thermodynamic parameters for the adsorption system were determinated at 293, 303, 313 and 323 K temperatures. The kinetic values and thermodynamic parameters from the adsorption process show that the Cr(VI) ions adsorption on boehmite is an endothermic and spontaneous process. These results show that the boehmite could be considered as a potential adsorbent for chromium ions in aqueous solutions.

  18. Chromium – An essential mineral

    Directory of Open Access Journals (Sweden)

    Merlin D Lindemann

    2009-09-01

    Full Text Available The status of chromium (Cr is not a new question. Cr is clearly an essential nutrient; this is a position that has been held for over three decades by individual scientists, groups of scientists, and governmental committees. The most uniform response across species with regard to Cr deficiency symptoms that are responsive to Cr supplementation are alterations in glucose metabolism with special reference to peripheral tissue sensitivity to insulin. Because the body’s ability to control blood glucose is critical to many life functions, and loss of ability to adequately control blood glucose can lead to many health debilitations, a consequence of Cr supplementation can be improved health and reproductive outcomes as well as improved survival rate or life span.

  19. Occupational asthma due to chromium.

    Science.gov (United States)

    Leroyer, C; Dewitte, J D; Bassanets, A; Boutoux, M; Daniel, C; Clavier, J

    1998-01-01

    We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated. PMID:9782225

  20. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past....... Processes that potentially fractionate Cr isotopes, perhaps during deposition, burial and alteration need to be constrained.Previous studies have shown that Cr isotopes are fractionated during oxidative weathering on land, where heavy Cr isotopes are preferentially removed with Cr(VI) while residual soils...... retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...

  1. Colloidally stable selenium@copper selenide core@shell nanoparticles as selenium source for manufacturing of copper-indium-selenide solar cells.

    Science.gov (United States)

    Dong, Hailong; Quintilla, Aina; Cemernjak, Marco; Popescu, Radian; Gerthsen, Dagmar; Ahlswede, Erik; Feldmann, Claus

    2014-02-01

    Selenium nanoparticles with diameters of 100-400nm are prepared via hydrazine-driven reduction of selenious acid. The as-prepared amorphous, red selenium (a-Se) particles were neither a stable phase nor were they colloidally stable. Due to phase transition to crystalline (trigonal), grey selenium (t-Se) at or even below room temperature, the particles merged rapidly and recrystallized as micronsized crystal needles. As a consequence, such Se particles were not suited for layer deposition and as a precursor to manufacture thin-film CIS (copper indium selenide/CuInSe2) solar cells. To overcome this restriction, Se@CuSe core@shell particles are presented here. For these Se@CuSe core@shell nanoparticles, the phase transition a-Se→t-Se is shifted to temperatures higher than 100°C. Moreover, a spherical shape of the particles is retained even after phase transition. Composition and structure of the Se@CuSe core@shell nanostructure are evidenced by electron microscopy (SEM/STEM), DLS, XRD, FT-IR and line-scan EDXS. As a conceptual study, the newly formed Se@CuSe core@shell nanostructures with CuSe acting as a protecting layer to increase the phase-transition temperature and to improve the colloidal stability were used as a selenium precursor for manufacturing of thin-film CIS solar cells and already lead to conversion efficiencies up to 3%. PMID:24267336

  2. Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jøns, O; Nielsen, B

    1992-01-01

    A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both sp....... The detection limit was 0.5 micrograms l-1 for both species. Data were in agreement with Zeeman-effect background corrected atomic absorption spectrometry measurements....

  3. Reduction of Diaryldiselenides by System of Cp2TiCl2/ BuiMgBr/ THF and Its Application in Synthesis of Unsymmetrical Diaryl Selenides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Reduction of diaryldiselenides by the system of Cp2TiCl2/BuiMgBr/THF gave the nucleophilic arylselenium complex. They reacted with diaryl iodonium salts to afford unsymmetrical diaryl selenides in high yields.

  4. AEROSOL BEHAVIOR IN CHROMIUM WASTE INCINERATION

    Institute of Scientific and Technical Information of China (English)

    Suyuan Yu

    2003-01-01

    Cr2O3 is considered as the dominant incineration product during the combustion disposal of chromium waste. A hydrogen/air diffusion flame was employed to simulate the industrial process of incineration. Cr2O3 aerosols were generated inside the flame by the gas phase reaction of chromium and oxygen. Chromium came from the rapid decomposition of chromium hexacarbonyl (Cr(CO)6) at room temperature and was carried into the combustion chamber by hydrogen. Aerosol and clusters can then be easily formed in the flame by nucleation and coagulation. A two dimensional Discrete-Sectional Model (DSM) was adopted to calculate the Cr2O3 aerosol behavior. The experimental measurement method was Dynamic Light Scattering. The numerically predicted results agreed well with those of the experimental measurement. Both results show that the Cr2O3 aerosol size reached about 70 nanometers at the flame top.

  5. Potentiometry: A Chromium (III) -- EDTA Complex

    Science.gov (United States)

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  6. Kinetics of growth and crystal structure of cadmium selenide films during vacuum condensation

    International Nuclear Information System (INIS)

    The growth and crystal structure of cadmium selenide films on mica are studied by electron-microscopic and electron-diffraction methods. The film condensation was carried out in wide temperature ranges of sublayers and densities of falling molecular flows. It is found that to describe the film nucleation processes in the first approximation the atomistic Wolton-Rodin method may be applied. Calculated is a number of atoms in the critical nucleus and energy nucleation parameters: activation energies of nucleation energies of adsorption and surface diffusion. It is shown that the crystal structure of thick films may be determined by the correlation of areas occupied by each type of particles up to the coalescence moment, and by the kinetics of autoepitaxial growth (depending on the mica type)

  7. A Rapid and Cost-Effective Laser Based Synthesis of High Purity Cadmium Selenide Quantum Dots.

    Science.gov (United States)

    Gondall, M A; Qahtan, Talal F; Dastageer, M A; Yamani, Z H; Anjum, D H

    2016-01-01

    A rapid and cost effective method is developed to synthesize high purity cadmium Selenide (CdSe) quantum dots in acetone medium using second harmonic of Nd:YAG nanosecond pulsed laser of 532 nm wavelength. The thermal agglomeration due the nanosecond pulse duration of the laser was successfully eliminated by using unfocussed laser beam and thereby providing a favorable conditions for the synthesis of quantum dots having the grain size of 3 nm. The morphological and optical characterizations like XRD, HRTEM, optical absorption of the synthesized CdSe quantum dots, reveal that the material possesses the similar characteristics of the one synthesized through cumbersome wet chemical methods. Relative to the CdSe bulk material, the synthesized CdSe quantum dots showed a blue shift in the measured band gap energy from near infrared spectral region to visible region, making this material very attractive for many solar energy harvesting applications like photo-catalysis and solar cells. PMID:27398538

  8. Photo-induced cooperative covalent-bond switching in amorphous arsenic selenide

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Balitska, V [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Filipecki, J [Institute of Physics of Jan Dlugosz University, 13/15, Al. Armii Krajowej, Czestochowa, PL-42201 (Poland)

    2005-01-01

    A microstructural mechanism of photoinduced transformations in amorphous arsenic selenide films was studied with IR Fourier-spectroscopy technique in 300-100 cm{sup -1} region. It was shown that stage of irreversible photostructural changes was connected with cooperative process of coordination defect formation accompanied by homopolar chemical bonds switching in heteropolar ones. On the contrary, reversible photoinduced effects were caused by heteropolar chemical bonds switching in homopolar ones, as well as additional channel of bridge heteropolar bonds switching in short-layer ones. The both processes were associated with formation of anomalously coordinated defect pairs and accompanying atomic displacements at the level of medium-range ordering. The developed mathematical simulation procedure testified in a favour of defect-related origin of the reversible photo-thermallyinduced transformations, since their kinetics corresponded to known stretched-exponential dependence, tending to bimolecular behaviour rather then to single-exponential one.

  9. Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O, E-mail: shpotyuk@novas.lviv.ua

    2010-11-15

    Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As{sub x}Se{sub 100-x} (10 {<=} x {<=} 42) and As{sub x}S{sub 100-x} (30 {<=} x {<=} 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As{sub x}S{sub 100-x} within 30 {<=} x < 40 range, while As{sub x}Se{sub 100-x} glasses from the same compositional interval do not show any measurable changes in DSC curves after {gamma}-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of {gamma}-induced excitations within sulfur-based network in comparison with selenium-based one.

  10. Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

    International Nuclear Information System (INIS)

    Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in AsxSe100-x (10 ≤ x ≤ 42) and AsxS100-x (30 ≤ x ≤ 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy AsxS100-x within 30 ≤ x xSe100-x glasses from the same compositional interval do not show any measurable changes in DSC curves after γ-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of γ-induced excitations within sulfur-based network in comparison with selenium-based one.

  11. Searching for new thermoelectric materials: some examples among oxides, sulfides and selenides

    International Nuclear Information System (INIS)

    Different families of thermoelectric materials have been investigated since the discovery of thermoelectric effects in the mid-19th century, materials mostly belonging to the family of degenerate semi-conductors. In the last 20 years, new thermoelectric materials have been investigated following different theoretical proposals, showing that nanostructuration, electronic correlations and complex crystallographic structures (low dimensional structures, large number of atoms per lattice, presence of ‘rattlers’…) could enhance the thermoelectric properties by enhancing the Seebeck coefficient and/or reducing the thermal conductivity. In this review, the different strategies used to optimize the thermoelectric properties of oxides and chalcogenides will be presented, starting with a review on thermoelectric oxides. The thermoelectric properties of sulfides and selenides will then be discussed, focusing on layered materials and low dimensional structures (TiS2 and pseudo-hollandites). Some sulfides with promising ZT values will also be presented (tetrahedrites and chalcopyrites). (topical review)

  12. Effect of cadmium selenide quantum dots on the dielectric and physical parameters of ferroelectric liquid crystal

    International Nuclear Information System (INIS)

    The effect of cadmium selenide quantum dots (CdSe QDs) on the dielectric relaxation and material constants of a ferroelectric liquid crystal (FLC) has been investigated. Along with the characteristic Goldstone mode, a new relaxation mode has been induced in the FLC material due to the presence of CdSe QDs. This new relaxation mode is strongly dependent on the concentration of CdSe QDs but is found to be independent of the external bias voltage and temperature. The material constants have also been modified remarkably due to the presence of CdSe QDs. The appearance of this new relaxation phenomenon has been attributed to the concentration dependent interaction between CdSe QDs and FLC molecules.

  13. Synthesis and characterization of lead selenide nanocrystal quantum dots and wires.

    Science.gov (United States)

    Seo, Weonsik; Yun, Ju-Hyung; Park, Yun Chang; Han, Chang-Soo; Lee, Jihye; Jeong, Sohee

    2011-05-01

    Lead chalcogenide nanocrystalline materials offer possibilities of improving the efficiency of various optoelectric/thermoelectric applications, especially in solar cells, by generating more carriers with incoming photons, or by extending the bandgap toward the infra-red region. In this work, we suggest the synthetic approach of creating extended PbSe structures which shows better performances when incorporated into an electric device. Firstly, we synthesized monodisperse cubic-structured single-crystalline lead selenide nanocrystal quantum dots using lead acetate and oleic acid in non-coordinating solvent without additional surfactants. Also, single-crystal cubic PbSe nanowires were synthesized in a mixture of surfactants such as trioctylphosphine and phenyl ether. Morphologies of wires and dots were precisely controlled via reaction temperature and the surface ligands. Phenyl ether was found to facilitate the oriented attachment. Further, current-voltage characteristics of drop-casted 2D arrays of nanocrystalline materials were examined. PMID:21780455

  14. Searching for new thermoelectric materials: some examples among oxides, sulfides and selenides

    Science.gov (United States)

    Hébert, S.; Berthebaud, D.; Daou, R.; Bréard, Y.; Pelloquin, D.; Guilmeau, E.; Gascoin, F.; Lebedev, O.; Maignan, A.

    2016-01-01

    Different families of thermoelectric materials have been investigated since the discovery of thermoelectric effects in the mid-19th century, materials mostly belonging to the family of degenerate semi-conductors. In the last 20 years, new thermoelectric materials have been investigated following different theoretical proposals, showing that nanostructuration, electronic correlations and complex crystallographic structures (low dimensional structures, large number of atoms per lattice, presence of ‘rattlers’…) could enhance the thermoelectric properties by enhancing the Seebeck coefficient and/or reducing the thermal conductivity. In this review, the different strategies used to optimize the thermoelectric properties of oxides and chalcogenides will be presented, starting with a review on thermoelectric oxides. The thermoelectric properties of sulfides and selenides will then be discussed, focusing on layered materials and low dimensional structures (TiS2 and pseudo-hollandites). Some sulfides with promising ZT values will also be presented (tetrahedrites and chalcopyrites).

  15. Structural, morphological and optical properties of nanocrystalline cadmium selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khomane, A.S., E-mail: ashok_khomane@rediffmail.co [Department of Chemistry, Government Rajaram College, S.U. Road, Vidyanagar, Kolhapur 416004, Maharashtra (India)

    2010-09-17

    Research highlights: {yields} CdSe thin films deposited first time by using malic acid as a complexing agent. {yields} The film samples were characterized by XRD, SEM, UV-vis-NIR spectroscopy and TEP techniques. {yields} Nanocrystalline CdSe film can be synthesized at room temperature. - Abstract: Nanocrystalline cadmium selenide thin films have been deposited on non-conducting glass substrates. The film samples were characterized by XRD, SEM, UV-vis-NIR reflection/absorption spectroscopy and TEP techniques. The annealed film samples showed a crystalline nature with a cubic crystal structure. The optical analysis showed direct band to band type of transition. The band gap of film sample was found to be in the order of 1.7 eV. The electrical conductivity of the film sample was found to be in the order of 10{sup -6} ({Omega} cm){sup -1}. TEP measurements show n-type of conductivity.

  16. Surface structure and optical property of amorphous carbon nanotubes hybridized with cadmium selenide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Kim Han, E-mail: kimhan8419@gmail.com; Johan, Mohd Rafie [University of Malaya, Nanomaterials Engineering Research Group, Advanced Materials Research Laboratory, Department of Mechanical Engineering (Malaysia)

    2013-09-15

    Amorphous carbon nanotubes ({alpha}-CNTs) were synthesized by a chemical reaction between ferrocene and ammonium chloride at low temperature. The as-synthesized {alpha}-CNTs were then hybridized with cadmium selenide quantum dots (CdSe QDs) through a simple chemical process. Raman spectra reveal the amorphous nature of the {alpha}-CNTs surface. X-ray diffraction pattern confirmed the amorphous phase of carbon and the formation of CdSe QDs crystalline phase. Field emission scanning electron microscopy and transmission electron microscopy (TEM and HRTEM) indicate that the successfully formed hybridized {alpha}-CNTs-CdSe QDs possess an average outer diameter in the range of 110-130 nm. The CdSe QDs fall in the size range of 15-40 nm. UV-visible spectroscopy showed quantum confinement effect due to the attachment of CdSe QDs on the surface of {alpha}-CNTs.

  17. Bifacial quantum dot-sensitized solar cells with transparent cobalt selenide counter electrodes

    Science.gov (United States)

    Ma, Chunqing; Tang, Qunwei; Zhao, Zhiyuan; Hou, Mengjin; Chen, Yuran; He, Benlin; Yu, Liangmin

    2015-03-01

    Elevation of power conversion efficiency and reduction of electricity-generation cost have been two persistent objectives for quantum dot-sensitized solar cells (QDSSCs). Here we report a bifacial QDSSC structure having impressive power conversion efficiencies of 2.11% and 1.28% for front and rear irradiations, respectively. The device comprises a CdS-sensitized TiO2 anode, a transparent cobalt selenide (Co-Se) counter electrode (CE), and a liquid electrolyte containing S2-/Sn2- redox couples. Due to high optical transparency of the binary Co-Se alloy CE, incident light can penetrate the QDSSC from either front or rear side for electron excitation. A fast start-up and modest photocurrent stability are determined in the bifacial QDSSCs due to the high electron transfer kinetics in CdS-sensitized TiO2 photoanode and electrocatalytic kinetics in Co-Se CE.

  18. The role of isomorphous substitutions in natural selenides belonging to the pyrite group

    Energy Technology Data Exchange (ETDEWEB)

    Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it; Cipriani, Curzio [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Pratesi, Giovanni [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Trosti-Ferroni, Renza [Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)

    2008-07-14

    The present paper reports chemical and structural data of selenide minerals belonging to the pyrite group. Eighteen samples of minerals in this group with variable chemical composition (7 samples of penroseite, NiSe{sub 2}; 10 samples of krutaite, CuSe{sub 2}; 1 sample of trogtalite, CoSe{sub 2}) were studied by means of X-ray single-crystal diffraction and electron microprobe. On the basis of information gained from the chemical characterization, we can conclude that a complete solid solution between NiSe{sub 2} and CuSe{sub 2} exists in nature with the absence of pure end-members. Although verified only for the Ni-rich members, we also infer a solid solution between NiSe{sub 2} and CoSe{sub 2}. The unit-cell parameters were modeled using a multiple regression method as a function of the Co, Ni, and Cu contents.

  19. Photo-induced cooperative covalent-bond switching in amorphous arsenic selenide

    International Nuclear Information System (INIS)

    A microstructural mechanism of photoinduced transformations in amorphous arsenic selenide films was studied with IR Fourier-spectroscopy technique in 300-100 cm-1 region. It was shown that stage of irreversible photostructural changes was connected with cooperative process of coordination defect formation accompanied by homopolar chemical bonds switching in heteropolar ones. On the contrary, reversible photoinduced effects were caused by heteropolar chemical bonds switching in homopolar ones, as well as additional channel of bridge heteropolar bonds switching in short-layer ones. The both processes were associated with formation of anomalously coordinated defect pairs and accompanying atomic displacements at the level of medium-range ordering. The developed mathematical simulation procedure testified in a favour of defect-related origin of the reversible photo-thermallyinduced transformations, since their kinetics corresponded to known stretched-exponential dependence, tending to bimolecular behaviour rather then to single-exponential one

  20. Effect of capping agents on optical and antibacterial properties of cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Deepika; Rakesh Dhar; Suman Singh; Atul Kumar

    2015-09-01

    Cadmium selenide quantum dots (CdSe QDs) were synthesized in aqueous phase by the freezing temperature injection technique using different capping agents (viz. thioglycolic acid, 1-thioglycerol, L-cysteine). Absorption spectra of CdSe QDs exhibited a blue shift as compared to its bulk counterpart, which is an indication of quantum confinement effect. The photoluminescence spectra of CdSe QDs confirmed that the particles are poly-dispersed and possess enhanced luminescent property, depending upon the chemical nature of capping agents. The QDs have been characterized by Fourier-transform infrared spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. Further, antimicrobial activity of as-prepared QDs has also been investigated using the disk diffusion method.

  1. Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts.

    Science.gov (United States)

    Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

    2013-10-21

    Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields. PMID:24056899

  2. Transparent nickel selenide alloy counter electrodes for bifacial dye-sensitized solar cells exceeding 10% efficiency

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2014-10-01

    In the current work, we report a series of bifacial dye-sensitized solar cells (DSSCs) that provide power conversion efficiencies of more than 10% from bifacial irradiation. The device comprises an N719-sensitized TiO2 anode, a transparent nickel selenide (Ni-Se) alloy counter electrode (CE), and liquid electrolyte containing I-/I3- redox couples. Because of the high optical transparency, electron conduction ability, electrocatalytic activity of Ni-Se CEs, as well as dye illumination, electron excitation and power conversion efficiency have been remarkably enhanced. Results indicate that incident light from a transparent CE has a compensation effect to the light from the anode. The impressive efficiency along with simple preparation of the cost-effective Ni-Se alloy CEs highlights the potential application of bifacial illumination technique in robust DSSCs.In the current work, we report a series of bifacial dye-sensitized solar cells (DSSCs) that provide power conversion efficiencies of more than 10% from bifacial irradiation. The device comprises an N719-sensitized TiO2 anode, a transparent nickel selenide (Ni-Se) alloy counter electrode (CE), and liquid electrolyte containing I-/I3- redox couples. Because of the high optical transparency, electron conduction ability, electrocatalytic activity of Ni-Se CEs, as well as dye illumination, electron excitation and power conversion efficiency have been remarkably enhanced. Results indicate that incident light from a transparent CE has a compensation effect to the light from the anode. The impressive efficiency along with simple preparation of the cost-effective Ni-Se alloy CEs highlights the potential application of bifacial illumination technique in robust DSSCs. Electronic supplementary information (ESI) available: Schematic diagram, repeated J-V curves, CV curves of Ni0.85Se electrode at various scan rates, relationship between peak current density and square root of scan rates. See DOI: 10.1039/c4nr03900a

  3. Bioremediation of chromium solutions and chromium containing wastewaters.

    Science.gov (United States)

    Malaviya, Piyush; Singh, Asha

    2016-08-01

    Cr(VI) represents a serious threat to human health, living resources and ecological system as it is persistent, carcinogenic and toxic, whereas, Cr(III), another stable oxidation state of Cr, is less toxic and can be readily precipitated out of solution. The conventional methods of Cr(VI) removal from wastewaters comprise of chemical reduction followed by chemical precipitation. However, these methods utilize large amounts of chemicals and generate toxic sludge. This necessitates the need for devising an eco-technological strategy that would use the untapped potential of the biological world for remediation of Cr(VI) containing wastewaters. Among several viable approaches, biotransformation of Cr(VI) to relatively non-toxic Cr(III) by chromium resistant bacteria offers an economical- and environment-friendly option for its detoxification. Various studies on use of Cr(VI) tolerant viable bacterial isolates for treatment of Cr(VI) containing solutions and wastewater have been reported. Therefore, a detailed account of mechanisms and processes involved in bioreduction of Cr(VI) from solutions and wastewaters by bacterial isolates are the focus of this review article in addition to a discussion on toxicity of Cr(VI) on bacterial strains and various factors affecting Cr(VI) bioreduction. PMID:25358056

  4. Diminishing Chromium Use on Combined Chromium-Gambier Tanning Process Upon the Characteristics of Tanned Leather

    Directory of Open Access Journals (Sweden)

    A. Kasim

    2014-04-01

    Full Text Available The research was aimed to investigate the influence of minimizing chromium use on combined chromium-gambier process upon the characteristics of tanned leather. At the first stage of tanning process, chromium was used and in the second stage it was replaced by gambier. The raw material used was dried saline-preserved goat skin. The treatments applied on the tanning process were the different concentrations of chromium ranging from the highest level of 6% to the lowest level of 1% which was then re-tanned by using 8% concentration of gambier. The examination parameters included chemical and physical properties as well as visual investigation on the tanned leather in accordance with SNI-06-0463-1989-A. The result showed that the tanning process by using 2% chromium in the first step and 8% gambier in the second step was a treatment combination producing tanned leather that met the standard. The examination on tanned leather resulted from such treatment showed 56.33% rawhide, 17.45% of bound tannin, 31.22% of tanning level, tensile strength 386.30 kg/cm2, flexibility 31.91%, leather width 1.3 mm, density 0.75 g/cm3, the leather was quite elastic with light brownish color. In conclusion, minimizing the use of chromium in the combined tanning process of chromium and gambier can be implemented to the lowest of 2% chromium concentration and 8% gambier in the first and second step, respectively.

  5. Lateral stress evolution in chromium sulfide cermets with varying excess chromium

    Science.gov (United States)

    Petel, O. E.; Appleby-Thomas, G. J.; Wood, D. C.; Capozzi, A.; Nabavi, A.; Goroshin, S.; Frost, D. L.; Hazell, P. J.

    2016-04-01

    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a one-dimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium contents.

  6. One-Step Synthesis of Colloidal Quantum Dots of Iron Selenide Exhibiting Narrow Range Fluorescence in the Green Region

    International Nuclear Information System (INIS)

    The instantaneous isolation of green fluorescent colloidal quantum dots of iron selenide capped with biocompatible oleic acid is reported in this study. These iron-containing quantum dots also serve as a safe alternative to the conventionally used metal-chalcogenide systems in which the heavy metal component is usually toxic. The isolated colored colloidal solutions exhibited intense green fluorescence on exposure to ultraviolet light, which was also confirmed by photoluminescence spectroscopy. The isolated product was subjected to dynamic light scattering and transmission electron microscopy, and the particles were found to exhibit spherical morphology with an average diameter of 6-8 nm, confirming the isolation of quantum dots. The isolated iron selenide quantum dots have promising potential towards bioimaging and sensing, due to the biocompatible coating of oleic acid and iron, which also allows possibility of further chemical derivatization.

  7. SIMS study of effect of Cr adhesion layer on the thermal stability of silver selenide thin films on Si

    International Nuclear Information System (INIS)

    Effect of heat treatment on silver selenide films grown from diffusion-reaction of Ag and Se films on Cr-buffered Si substrates was investigated up to 400 deg. C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the films. XRD patterns of the films showed stress assisted change in preferential orientation of the films upon annealing: the films annealed at 200 deg. C exhibited a strong orientation along (2 0 0) plane, which changed to (0 1 3) after annealing at 300 and 400 deg. C. Dynamic SIMS measurements showed that Cr is confined to the interface and that there is no diffusion of Cr into silver selenide

  8. The Short Series of the Oxygen-Poor Lanthanide Oxide Selenides M10OSe14 with M = La–Nd

    Directory of Open Access Journals (Sweden)

    Frank A. Weber

    2012-08-01

    Full Text Available Single crystals and phase pure samples of oxygen-poor ternary lanthanide oxide selenides with the composition M10OSe14 (M = La–Nd; tetragonal, I41/acd; a = 1592.0–1559.8 pm, c = 2106.5–2062.9 pm could be obtained by reacting the corresponding metals, selenium and selenium dioxide as oxygen source. Their crystal structures are isotypic with Pr10OS14 and thus contain isolated [OM4]10+ tetrahedra (d(O2––M3+ = 243–248 pm embedded in a complex anionic {[M6Se14]10–} lanthanide selenide matrix (d(M3+–Se2– = 288–358 pm. All three crystallographically independent M3+ cations exhibit eight contacts to chalcogenide anions (O2– and/or Se2– resulting in the formation of bicapped trigonal prismatic coordination polyhedra. The optical band gaps of the oxide selenides M10OSe14 amount to values between 1.89 and 2.04 eV indicating wide band-gap semiconductors.

  9. The enriched chromium neutrino source for GALLEX

    International Nuclear Information System (INIS)

    The preparation and study of an intense source of neutrinos in the form of neutron irradiated materials which are enriched in Cr-50 for use in the GALLEX solar neutrino experiment are discussed. Chromyl fluoride gas is enriched in the Cr-50 isotope by gas centrifugation and subsequently converted to a very stable form of chromium oxide. The results of neutron activation analyses of such chromium samples indicate low levels of any long-lived activities, but show that short-lived activities, in particular Na-24, may be of concern. These results show that irradiating chromium oxide enriched in Cr-50 is preferable to irradiating either natural chromium or argon gas as a means of producing a neutrino source to calibrate the GALLEX detector. These results of the impurity level analysis of the enriched chromyl fluoride gas and its conversion to the oxide are also of interest to work in progress by other members of the Collaboration investigating an alternative conversion of the enriched gas to chromium metal. 35 refs., 12 figs., 5 tabs

  10. Serum chromium levels in gestational diabetes mellitus

    Directory of Open Access Journals (Sweden)

    P G Sundararaman

    2012-01-01

    Full Text Available Objective: To measure serum chromium level in women with gestational diabetes mellitus (GDM from Chennai, South India. Materials and Methods: Thirty women with gestational diabetes, 60 age matched controls. Inclusion criteria: Gestational age 22-28 weeks, age group 20-35 years. Exclusion Criteria: Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer. Results: Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml (P < 0.001. However, there were no significant differences among cases and controls when subdivided by parity. Conclusions: Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

  11. Occupational exposure to chromium(VI compounds

    Directory of Open Access Journals (Sweden)

    Jolanta Skowroń

    2015-07-01

    Full Text Available This article discusses the effect of chromium(VI (Cr(VI on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV for chromium(VI of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL document chromium(VI concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2–14 cases per 1000 exposed workers. Exposure to chromium(VI compounds expressed in Cr(VI of 0.01 mg Cr(VI/m3 is responsible for the increased number of lung cancer cases in 1–6 per 1000 people employed in this condition for the whole period of professional activity. Med Pr 2015;66(3:407–427

  12. [Occupational exposure to chromium(VI) compounds].

    Science.gov (United States)

    Skowroń, Jolanta; Konieczko, Katarzyna

    2015-01-01

    This article discusses the effect of chromium(VI) (Cr(VI)) on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI) compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV) for chromium(VI) of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL) document chromium(VI) concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2-14 cases per 1000 exposed workers. Exposure to chromium(VI) compounds expressed in Cr(VI) of 0.01 mg Cr(VI)/m3; is responsible for the increased number of lung cancer cases in 1-6 per 1000 people employed in this condition for the whole period of professional activity. PMID:26325053

  13. Flashlamp-pumped lasing of chromium-doped GSG garnet

    International Nuclear Information System (INIS)

    The implications for the practical use of chromium:GSGG in lamp-pumped tunable lasers are discussed in this paper. The authors report here some major improvements in the performance of the flashlamp-pumped chromium:GSGG laser

  14. Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

    OpenAIRE

    Weckhuysen, B. M.; Wachs, I.E.; Schoonheydt, R. A.

    1996-01-01

    Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

  15. Studies of Some Novel Chromium Pyridine Dicarboxylate Complexes

    OpenAIRE

    Chauhan Jayprakash S; Patel Rameshchandra P; Pandya Ajit V

    2014-01-01

    Chromium pyridine di-carboxylate complexes are synthesized from Chromium (III) with pyridine 2, 6- dicarboxylic acid, pyridine 2, 3 and 2, 5- dicarboxylic acids. Chromium forms colored complexes. Chromium (III) forms a violate complex with pyridine 2, 6- dicarboxylic acid and purple violate complex with pyridine 2, 3 and 2, 5- dicarboxylic acids. The job’s method indicates metal ligand ratio to be 1:2. The interpretation of UV-VIS spectra indicates octahedral geometry and IR spectra give clue...

  16. Determination of chromium combined with DNA, RNA and proteins in chromium-rich brewer's yeast by NAA

    International Nuclear Information System (INIS)

    The content of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast was determined by neutron activation analysis (NAA). Our results show that the extracted relative amounts and concentrations of DNA, RNA and proteins have no significant difference for two types of yeast, but the chromium content in DNA, RNA and proteins fractions extracted from the chromium-rich yeast are substantially higher than those from the normal. In addition, the concentration of chromium in DNA is much higher than that in RNA and proteins. It is evident that the inorganic chromium compounds can enter the yeast cell during the yeast cultivation in the chromium-containing culture medium and are converted into organic chromium species, which are combined with DNA, RNA and proteins. (author)

  17. Chromium allergy and dermatitis: prevalence and main findings

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl;

    2015-01-01

    The history of chromium as an allergen goes back more than a century, and includesan interventional success with national legislation that led to significant changes inthe epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium...

  18. 21 CFR 73.1326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  19. 21 CFR 73.2326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  20. Thermodynamic properties of chromium bearing slags and minerals. A review

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Yanping; Holappa, L.

    1996-12-31

    In this report, the thermodynamic properties of chromium bearing slags and minerals were reviewed based on the available information in the literature. It includes the analysing methods for oxidation state of chromium in slags, oxidation state of chromium and activities of chromium oxides in slags and minerals. The phase diagrams of chromium oxide systems and chromium distributions between slag and metal phases are also covered ill this review. Concerning the analysing methods, it was found that most of the available approaches are limited to iron free slag systems and the sample preparation is very sensitive to the analysing results. In silicate slags under reducing atmosphere, divalent and trivalent chromium co-exist in the slags. It is agreed that the fraction of divalent chromium to total chromium increases with higher temperature, lower slag basicity and oxygen potential. For the slags under oxidising atmosphere, trivalent, pentavalent and hexavalent states were reported to be stable. The activities of CrO and CrO{sub 1.5} were concluded to have positive deviation from ideal solution. Slag basicity has a positive effect and temperature has a negative effect on the activities of chromium oxides. The phase diagrams of the Cr-O, binary, and ternary chromium containing oxide systems have been examined systematically. The analysis shows that the data on the quaternary and quinary systems are insufficient, and require further investigation. The most important features of the chromium containing silicate slags are the large miscibility gaps and the stability of the chromite spinel. (orig.) (76 refs.)

  1. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining...

  2. Hexavalent and trivalent chromium in leather: What should be done?

    Science.gov (United States)

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions. PMID:26361854

  3. SAFETY OF TRIVALENT CHROMIUM COMPLEXES USED IN NUTRIENT SUPPLEMENTS

    Science.gov (United States)

    Toxicity studies regarding trivalent chromium have often been completed under conditions that are not designed to reflect conditions that would be encountered under normal physiological conditions. We have shown that the incorporation of chromium into tissues of rats from chromium chloride and chro...

  4. Strategies for chromium bioremediation of tannery effluent.

    Science.gov (United States)

    Garg, Satyendra Kumar; Tripathi, Manikant; Srinath, Thiruneelakantan

    2012-01-01

    Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and

  5. Collisional properties of trapped cold chromium atoms

    CERN Document Server

    Pavlovich, Z; Côté, R; Sadeghpour, H R; Pavlovic, Zoran; Roos, Bjoern O.; Côté, Robin

    2004-01-01

    We report on calculations of the elastic cross section and thermalization rate for collision between two maximally spin-polarized chromium atoms in the cold and ultracold regimes, relevant to buffer-gas and magneto-optical cooling of chromium atoms. We calculate ab initio potential energy curves for Cr2 and the van der Waals coefficient C6, and construct interaction potentials between two colliding Cr atoms. We explore the effect of shape resonances on elastic cross section, and find that they dramatically affect the thermalization rate. Our calculated value for the s-wave scattering length is compared in magnitude with a recent measurement at ultracold temperatures.

  6. Influence of nitrogen on the structure and properties of chromium, chromium-molybdenum and chromium-manganese steels

    International Nuclear Information System (INIS)

    Phase transformations, precipitation processes and properties of the chromium, chromium-molybdenum and chromium-manganese steels with a high content of nitrogen as the dependence on thermal treatment were investigated. In case of Fe-0.08C-18Cr-18Mn-N and Fe-0.08C-18Cr-18Mn-2Mo-N steels the samples in the state after solution at temperature 1050oC and 1150oC and 1250oC and after subsequent annealing in 600oC and 800oC were investigated. heat treatment of the Fe-0.5C-10Cr-N and Fe-0.5C-10Cr-1Mo-N steels included austenitizment from 1000oC with air cooling and hardening from 1000oC with oil cooling and tempering in 650oC and 750oC in two hours with cooling in the air. These investigations show that the influence of nitrogen as an alloy element on the phase transformations, precipitation processes, mechanical and corrosion properties is connected with the presence of molybdenum and chromium in the steel. Nitrogen with these elements creates complex ions with the coordinate number 6. This statement is formed on the base of both calculations and investigation results. (author)

  7. Development of the data base for a degradation model of a selenide RTG

    International Nuclear Information System (INIS)

    A new class of high temperature thermoelectric materials composed of copper, silver and selenium for the p-type and gadolinium-selenium for the n-type has been developed by the 3M Company, who also assembles the thermopile. The use of these materials for space applications (commonly referred to as the selenides) is being actively pursued by the Teledyne Corporation, under the sponsorship of ERDA. Application of this new generation of thermoelectric generators as the primary power source for unmanned spaceflight missions is under consideration by JPL. The viability of a radioisotope thermoelectric generator (RTG) strongly depends upon the long-term electrical, thermal and dimensional stability of this newly developed TPM-217 thermoelectric material. To determine independently this material's time and temperature dependent stability parameters is the goal of an extensive experimental and analytical project conducted at JPL. To realize this goal, a threefold approach is being used: (1) to determine if, and at what rate, the thermal conductance of the TPM material changes, (2) to investigate the long-term stability of the material's Seebeck voltage and electrical resistivity under current and temperature gradient conditions, and (3) to ascertain the physical behavior and compatibility of the material with surrounding insulation at elevated temperatures

  8. Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

    Science.gov (United States)

    Bercegol, Adrien; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch.; Liero, Matthias

    2016-04-01

    For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

  9. Highly efficient copper-zinc-tin-selenide (CZTSe) solar cells by electrodeposition.

    Science.gov (United States)

    Jeon, Jong-Ok; Lee, Kee Doo; Seul Oh, Lee; Seo, Se-Won; Lee, Doh-Kwon; Kim, Honggon; Jeong, Jeung-hyun; Ko, Min Jae; Kim, BongSoo; Son, Hae Jung; Kim, Jin Young

    2014-04-01

    Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties. PMID:24692285

  10. Multifunctional Bismuth Selenide Nanocomposites for Antitumor Thermo-Chemotherapy and Imaging.

    Science.gov (United States)

    Li, Zhenglin; Hu, Ying; Howard, Kenneth A; Jiang, Tingting; Fan, Xuelei; Miao, Zhaohua; Sun, Ye; Besenbacher, Flemming; Yu, Miao

    2016-01-26

    To integrate real-time monitoring and therapeutic functions into a single nanoagent, we have designed and synthesized a drug-delivery platform based on a polydopamine(PDA)/human serum albumin (HSA)/doxorubicin (DOX) coated bismuth selenide (Bi2Se3) nanoparticle (NP). The resultant product exhibits high stability and biocompatibility both in vitro and in vivo. In addition to the excellent capability for both X-ray computed tomography (CT) and infrared thermal imaging, the NPs possess strong near-infrared (NIR) absorbance, and high capability and stability of photothermal conversion for efficient photothermal therapy (PTT) applications. Furthermore, a bimodal on-demand pH/photothermal-sensitive drug release has been achieved, resulting in a significant chemotherapeutic effect. Most importantly, the tumor-growth inhibition ratio achieved from thermo-chemotherapy of the Bi2Se3@PDA/DOX/HSA NPs was 92.6%, in comparison to the chemotherapy (27.8%) or PTT (73.6%) alone, showing a superior synergistic therapeutic effect. In addition, there is no noticeable toxicity induced by the NPs in vivo. This multifunctional platform is, therefore, promising for effective, safe and precise antitumor treatment and may stimulate interest in further exploration of drug loading on Bi2Se3 and other competent PTT agents combined with in situ imaging for biomedical applications. PMID:26655250

  11. Light-emitting diodes made from cadmium selenide nanocrystals and a semiconducting polymer

    Science.gov (United States)

    Colvin, V. L.; Schlamp, M. C.; Alivisatos, A. P.

    1994-08-01

    ELECTROLUMINESCENT devices have been developed recently that are based on new materials such as porous silicon1 and semiconducting polymers2,3. By taking advantage of developments in the preparation and characterization of direct-gap semiconductor nanocrystals4-6, and of electroluminescent polymers7, we have now constructed a hybrid organic/inorganic electroluminescent device. Light emission arises from the recombination of holes injected into a layer of semiconducting p-paraphenylene vinylene (PPV)8-10 with electrons injected into a multilayer film of cadmium selenide nanocrystals. Close matching of the emitting layer of nanocrystals with the work function of the metal contact leads to an operating voltage11 of only 4V. At low voltages emission from the CdSe layer occurs. Because of the quantum size effect19-24 the colour of this emission can be varied from red to yellow by changing the nanocrystal size. At higher voltages green emission from the polymer layer predominates. Thus this device has a degree of voltage tunability of colour.

  12. Synthesis of Co-Electrospun Lead Selenide Nanostructures within Anatase Titania Nanotubes for Advanced Photovoltaics

    Directory of Open Access Journals (Sweden)

    Evan K. Wujcik

    2015-06-01

    Full Text Available Inorganic nano-scale heterostructures have many advantages over hybrid organic-inorganic dye-sensitized solar cells (DSSC or Grätzel cells, including their resistance to photo-bleaching, thermal stability, large specific surface areas, and general robustness. This study presents a first-of-its-kind low-cost all-inorganic lead selenide-anatase titania (PbSe/TiO2 nanotube heterostructure material for photovoltaic applications. Herein, PbSe nanostructures have been co-electrospun within a hollow TiO2 nanotube with high connectivity for highly efficient charge carrier flow and electron-hole pair separation. This material has been characterized by transmission electron microscopy (TEM, electron diffraction, energy dispersive X-ray spectroscopy (EDX to show the morphology and material composition of the synthesized nanocomposite. Photovoltaic characterization has shown this newly synthesized proof-of-concept material can easily produce a photocurrent under solar illumination, and, with further refinement, could reveal a new direction in photovoltaic materials.

  13. New route for preparation of luminescent mercaptoethanoate capped cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Manoj E Wankhede; Shaukatali N Inamdar; Aparna Deshpande; Aniket R Thete; Renu Pasricha; Sulabha K Kulkarni; Santosh K Haram

    2008-06-01

    We report a synthesis of cadmium selenide quantum dots (Q-CdSe) by refluxing a mixture of cadmium acetate, selenium powder, sodium sulfite and 2-mercaptoethanol in N,N′-dimethyl formamide (DMF)/water solution. X-ray and electron diffractions suggest the formation of hexagonal phase of size quantized CdSe. Based on TEM analysis, the formation of nanoparticles with an average diameter of 3.5 ± 0.5 nm is inferred. Their sols in DMF and dimethyl sulphoxide (DMSO) gave characteristic absorption peaks at 300 nm and 327 nm, which is attributed to the formation of high quality, size quantized CdSe particles. Extracted particles from the sol were readily redispersed in DMF and DMSO, which were diluted further with water without losing their optical and colloidal properties. FTIR spectroscopy suggested the formation of 2-mercaptoethanol thiolate on the particle surface, with free –OH groups available for linkage. Sols in DMSO and their solutions in water displayed an intense photoluminescence (PL).

  14. Bifacial dye-sensitized solar cells with transparent cobalt selenide alloy counter electrodes

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; He, Benlin; Zhao, Zhiyuan; Zhu, Ling; Yu, Liangmin

    2015-06-01

    High power conversion efficiency and cost-effectiveness are two persistent objectives for dye-sensitized solar cell (DSSC). Electricity generation from either front or rear side of a bifacial DSSC has been considered as a facile avenue of bringing down the cost of solar-to-electric conversion. Therefore, the fabrication of a transparent counter electrode (CE) with a high electrocatalytic activity is a prerequisite to realize this goal. We present here the feasibility of utilizing transparent cobalt selenide (Co-Se) binary alloy counter electrode for bifacial DSSC application, in which binary Co-Se alloy electrode is synthesized by a mild solution strategy and the cell device is irradiated by either front or rear side. Due to the high optical transparency, charge-transfer ability, and electrocatalytic activity, maximum front and rear efficiencies of 8.30% and 4.63% are recorded under simulated air mass 1.5 (AM1.5) irradiation, respectively. The impressive efficiency along with fast start-up, multiple start capability, and simple preparation highlights the potential application of cost-effective and transparent Co-Se alloy CE in robust bifacial DSSCs.

  15. DFT Study on the Carrier Concentration and Temperature-Dependent Thermoelectric Properties of Antimony Selenide

    Directory of Open Access Journals (Sweden)

    Aditya Jayaraman

    2016-01-01

    Full Text Available We present the thermoelectric properties of Antimony Selenide (Sb2Se3 obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BoltzTrap code using the constant relaxation time (τ approximation at three different temperatures 300 K, 600 K, and 800 K. Seebeck coefficient (S was found to decrease with increasing temperature, electrical conductivity (σ/τ was almost constant in the entire temperature range, and electronic thermal conductivity (κ/τ increased with increasing temperature. With increase in temperature S decreased from 1870 μV/K (at 300 K to 719 μV/K (at 800 K, electronic thermal conductivity increased from 1.56 × 1015 W/m K s (at 300 K to 3.92 × 1015 W/m K s (at 800 K, and electrical conductivity decreased from 22 × 1019/Ω m s (at 300 K to 20 × 1019/Ω m s (at 800 K. The thermoelectric properties were also calculated for different hole concentrations and the optimum concentration for a good thermoelectric performance over a large range of temperatures (from 300 K to 1000 K was found for hole concentration around 1019 cm−3.

  16. Femtosecond Transient Absorption Studies in Cadmium Selenide Nanocrystal Thin Films Prepared by Chemical Bath Deposition Method

    Directory of Open Access Journals (Sweden)

    M. C. Rath

    2007-01-01

    Full Text Available Dynamics of photo-excited carrier relaxation processes in cadmium selenide nanocrystal thin films prepared by chemical bath deposition method have been studied by nondegenerate femtosecond transient pump-probe spectroscopy. The carriers were generated by exciting at 400 nm laser light and monitored by several other wavelengths. The induced absorption followed by a fast bleach recovery observed near and above the bandgap indicates that the photo-excited carriers (electrons are first trapped by the available traps and then the trapped electrons absorb the probe light to show a delayed absorption process. The transient decay kinetics was found to be multiexponential in nature. The short time constant, <1 picosecond, was attributed to the trapping of electrons by the surface and/or deep traps and the long time constant, ≥20 picoseconds, was due to the recombination of the trapped carriers. A very little difference in the relaxation processes was observed in the samples prepared at bath temperatures from 25∘C to 60∘C.

  17. A new wide band gap thermoelectric quaternary selenide Cu2MgSnSe4

    Science.gov (United States)

    Pavan Kumar, V.; Guilmeau, Emmanuel; Raveau, Bernard; Caignaert, Vincent; Varadaraju, U. V.

    2015-10-01

    Cu2MgSnSe4 based compounds composed of high earth abundant elements have been identified to exhibit good thermoelectric performance in the mid-temperature range. The pristine phase shows a band gap of 1.7 eV, which is slightly higher than similar ternary and quaternary copper based stannite compounds. Cu2MgSnSe4 crystallizes in the tetragonal I 4 ¯ 2m space group. Substitution of In at Sn site tends to decrease the tetragonal distortion toward the cubic symmetry. The electrical and thermal transport properties of Cu and In-doped Cu2MgSnSe4 in the temperature range of 300 K-700 K are studied. The substitution of In3+ for Sn4+ and Cu2+ for Mg2+ induces charge carriers as holes, which in turn lead to improvement in thermoelectric efficiency. The role of mass fluctuations and structural disorder in the evolution of the thermal conductivity of the doped selenides is discussed. A maximum ZT of 0.42 is attained for Cu2MgSn0.925In0.075Se4 around 700 K, and this value is comparable to that of Cu2ZnSnSe4.

  18. Noncentrosymmetric selenide Ba4Ga4GeSe12: Synthesis, structure, and optical properties

    Science.gov (United States)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Lin, Xinsong; Yao, Jiyong; Mar, Arthur

    2016-09-01

    The selenide Ba4Ga4GeSe12, synthesized by reaction of BaSe, Ga2Se3, and GeSe2 at 1173 K, adopts a noncentrosymmetric tetragonal structure (space group P 4 bar21 c , Z=2, a=13.5468(4) Å, c=6.4915(2) Å) consisting of a three-dimensional network built from two types of corner-sharing MSe4 tetrahedra, with Ba cations occupying the intervening voids. It is isostructural to Pb4Ga4GeS12, Pb4Ga4GeSe12, and Ba4Ga4SnSe12, but differs subtly in site ordering. Structural refinements and bond valence sum analysis suggest partial disorder manifested by mixing of 0.75 Ga and 0.25 Ge within one tetrahedral site, and occupation of exclusively Ga within the other tetrahedral site. The optical band gap of 2.18(2) eV, measured from the UV/VIS/NIR diffuse reflectance spectrum, agrees with a calculated gap of 2.35 eV between valence and conduction bands and is consistent with the orange-yellow color of the crystals. Nonlinear optical measurements on powder samples revealed a weak second harmonic generation signal using 2.09 μm as the fundamental laser wavelength.

  19. Ab-Initio Computations of Electronic and Related Properties of cubic Lithium Selenide (Li2Se)

    Science.gov (United States)

    Goita, Abdoulaye; Nwigboji, Ifeanyi H.; Malozovsky, Yuriy; Bagayoko, Diola

    We present theoretical predictions, from ab-initio, self-consistent calculations, of electronic and related properties of cubic lithium selenide (Li2Se). We employed a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). We performed the computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Our results include electronic energies, total and partial densities of states, effective masses, and the bulk modulus. The theoretical equilibrium lattice constant is 5.882 Å. We found cubic Li2Se to have a direct band gap of 4.363 eV (prediction), at Γ. This gap is 4.065 eV for a room temperature lattice constant of 6.017 Å. The calculated bulk modulus is 31.377 GPa. Acknowledgments: This work was funded in part by the National Science Foundation (NSF) and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR] and NSF HRD-1002541, the US Department of Energy - National, Nuclear Security Administration (NNSA) (Award No. DE- NA0002630), LaSPACE, and LONI-SUBR.

  20. Layered bismuth selenide utilized as hole transporting layer for highly stable organic photovoltaics

    KAUST Repository

    Yuan, Zhongcheng

    2015-11-01

    Abstract Layered bismuth selenide (L-Bi2Se3) nanoplates were implemented as hole transporting layers (HTLs) for inverted organic solar cells. Device based on L-Bi2Se3 showed increasing power conversion efficiency (PCE) during ambient condition storage process. A PCE of 4.37% was finally obtained after 5 days storage, which outperformed the ones with evaporated-MoO3 using poly(3-hexylthiophene) (P3HT) as donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The improved device efficiency can be attributed to the high conductivity and increasing work function of L-Bi2Se3. The work function of L-Bi2Se3 increased with the storage time in ambient condition due to the oxygen atom doping. Ultraviolet photoelectron spectroscopy and high resolution X-ray photoelectron spectroscopy were conducted to verify the increased work function, which originated from the p-type doping process. The device based on L-Bi2Se3 exhibited excellent stability in ambient condition up to 4 months, which was much improved compared to the device based on traditional HTLs. © 2015 Elsevier B.V.

  1. Electrodeposition of black chromium thin films from trivalent chromium-ionic liquid solution

    OpenAIRE

    Eugénio, S.; Vilar, Rui; C. M. Rangel; Baskaran, I.

    2009-01-01

    In the present study, black chromium thin films were electrodeposited from a solution of 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIm][BF4] ionic liquid containing trivalent chromium (Cr(III)). Homogeneous and well adherent coatings have been obtained on nickel, copper and stainless steel substrates. The nucleation and growth of the films were investigated by cyclic voltammetry and current-density/time transient techniques. SEM/EDS, XPS and XRD were used to study the morphology, chem...

  2. Reduction of Hexavalent Chromium by Viable Cells of Chromium Resistant Bacteria Isolated from Chromite Mining Environment

    OpenAIRE

    Satarupa Dey; Baishali Pandit; A. K. Paul

    2014-01-01

    Environmental contamination of hexavalent chromium [Cr(VI)] is of serious concern for its toxicity as well as mutagenic and carcinogenic effects. Bacterial chromate reduction is a cost-effective technology for detoxification as well as removal of Cr(VI) from polluted environment. Chromium resistant and reducing bacteria, belonging to Arthrobacter, Pseudomonas, and Corynebacterium isolated from chromite mine overburden and seepage samples of Orissa, India, were found to tolerate 12–18 mM Cr(VI...

  3. Reduction of Chromium-VI by Chromium Resistant Lactobacilli: A Prospective Bacterium for Bioremediation

    OpenAIRE

    Mishra, Ritesh; Sinha, Vartika; Kannan, Ambrose; Upreti, Raj K.

    2012-01-01

    Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr (VI) and Cr (III). Highly soluble hexavalent chromium is carcinogenic due to its oxidizing nature. It is well established that the intestinal bacteria including Lactobacilli have regulatory effect on intestinal homeostasis and a breakdown in the relationship between intestinal cells and bacteria results in the manifestation of gastrointestinal (GI) disorders. In this study Cr (VI) resistance was developed in La...

  4. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    OpenAIRE

    Mirković Nemanja

    2007-01-01

    Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimenta...

  5. Chromium-manganese steels of transition class

    International Nuclear Information System (INIS)

    Possibilities of nickel replacing by manganese and preparing the same level of mechanical properties as in chromium-nickel steels due to γ-α transformations taking place during property tests, are studied. Chromium-manganese steels with the composition of 0.05-0.1%C, 13-14%Cr, 5.0-6.5%Mn, 0.2-0.5%Si, 0.03-0.13%N, 0.05-0.01%Al and additionally alloyed 0.3-2.0%Cu, 0.05-0.6%V, 0.3-1.0%Mo, 0.02-0.05%Ca in various combinations have been melted. It is shown, that using alloying and heat treatment one can control the phase composition, austenite resistance to martensite transformation during loading and mechanical properties of chromium-manganese steels of the transition class. The use of the phase transformation in the process of testing determines the level of mechanical properties. The optimum development of the transformation accompanied by a sufficient development of processes of hardening and microstresses relaxation permits to obtain a high level of mechanical properties: σsub(B)=1500 MPa, σsub(0.2)-1130MPa, delta=15%, psi=37%, asub(H)=1000 kJ/msup(2) which exceeds the level for chromium-nickel steels. Steels have a lower cost and do not require any complecated heat treatment regime

  6. Defect structure of electrodeposited chromium layers

    International Nuclear Information System (INIS)

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  7. Defect structure of electrodeposited chromium layers

    CERN Document Server

    Marek, T; Vertes, A; El-Sharif, M; McDougall, J; Chisolm, C U

    2000-01-01

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  8. Flashlamp-pumped lasing of chromium: GSGG

    International Nuclear Information System (INIS)

    Lasing action in chromium-doped gadolinium scandium gallium garnet (Cr:GSGG) is well established for both CW/sup (1)/ and flashlamp/sup (2)/ pumping. This paper describes an investigation of flashlamp-pumped Cr:GSGG lasers and indicates some of the factors which limit performance

  9. Trace Elements Excluding Iron - Chromium and Zinc

    Science.gov (United States)

    The percentage of middle-aged US adults who are participating in leisure-time physical activities is growing. These adults also seek credible information about specific supplements that the public press routinely describes as necessary to enable increases in physical performance. Chromium and zinc a...

  10. HEALTH ASSESSMENT DOCUMENT FOR CHROMIUM. FINAL REPORT

    Science.gov (United States)

    The full document represents a comprehensive data base that considers all sources of chromium in the environment, the likelihood for its exposure to humans, and the possible consequences to man and lower organisms from its absorption. This information is integrated into a format ...

  11. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1926.51 Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1926.51. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  12. 29 CFR 1910.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1910.141. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  13. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1915.97. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  14. Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects.

    Science.gov (United States)

    Lindström, David; Hedberg, Yolanda; Odnevall Wallinder, Inger

    2010-06-01

    The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site. PMID:20462267

  15. Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

    Science.gov (United States)

    Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

    2016-06-01

    The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively. PMID:26971177

  16. Nephrotoxic and hepatotoxic effects of chromium compounds in rats

    Energy Technology Data Exchange (ETDEWEB)

    Laborda, R.; Diaz-Mayans, J.; Nunez, A.

    1986-03-01

    The nephrotoxic, hepatotoxic and cardiotoxic actions of hexavalent chromium compounds, as well as their effects on lung, blood and circulation may contribute to the fatal outcome of chromium intoxication. Although trivalent chromium have been regarded as relatively biologically inert, there are a few salts of chromium III that have been found to be carcinogenic when inhaled, ingested or brought in contact with the tissues. Sensitive persons and industry workers have been subjects of dermatitis, respiratory tract injuries and digestive ulcers due to chromium compounds. In this work, the authors have studied the effect of trivalent and hexavalent chromium compounds on rats measuring the transaminases (GOT and GPT), urea and creatinine levels in serum of chromium poisoned animals at different times.

  17. A Kinetic Model of Chromium in a Flame

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chromium has been identified as a carcinogenic metal.Incineration is the useful method for disposal of toxic chromium hazard waste and a chromium kinetic model in a flame is very important to study chromium oxidation.Chromium chemical kinetics over a range of temperatures of a hydrogen/air flame is proposed.Nine chromium compounds and fifty-eight reversible chemical reactions were considered The forward reaction rates are calculated based on the molecular collision approach for unknown ones and Arrhenius's Law for known ones.The backward reaction rates were calculated according to forward reaction rates, the equilibrium constants and chemical thermodynamics.It is verified by several equilibrium cases and is tested by a hydrogen/air diffusion flame.The results show that the kinetic model could be used in cases in which the chromium kinetics play an important role in a flame

  18. The Chromium is an essential element in the human

    International Nuclear Information System (INIS)

    The Chromium is an essential element for human and animals, because it a preponderant function in the insulin metabolism as a glucose tolerance factor (GTF). The deficiency of chromium engenders a deterioration in the glucose metabolism due to bad efficiency of insulin. Because the importance of this element an exhaustive reference review was made and this presents some studies realized in laboratory animals and in human beings where it is prove with resuits the effect of chromium over the improvement of patients with non-insulin dependant diabetes. Three substances are presented as chromium active biological forms: a material rich in chromium known as glucose tolerance factor, chromium picolinate and a substance of low molecular weight LMWCr in its forms of apo and holo that contains chromium and it links the insulin receptor and improves its activity. Also this paper presents information about the condition of diabetes in Costa Rica. (Author)

  19. Reaction of chromium(VI) with glutathione or with hydrogen peroxide: identification of reactive intermediates and their role in chromium(VI)-induced DNA damage.

    OpenAIRE

    Aiyar, J; Berkovits, H J; Floyd, R A; Wetterhahn, K E

    1991-01-01

    The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI) with glutathione led to formation of two chromium(V) complexes and the glutathione thiyl radical. When chromium(VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chrom...

  20. Design and performance of chromium mist generator

    Directory of Open Access Journals (Sweden)

    Tirgar Aram

    2006-01-01

    Full Text Available Chromium mist generator is an essential tool for conducting researches and making science-based recommendations to evaluate air pollution and its control systems. The purpose of this research was to design and construct a homogenous chromium mist generator and the study of some effective factors including sampling height and distances between samplers in side-by-side sampling on chromium mist sampling method. A mist generator was constructed, using a chromium electroplating bath in pilot scale. Concentration of CrO3 and sulfuric acid in plating solution was 125 g L-1 and 1.25 g L-1, respectively. In order to create permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d was installed the bath overhead. Sixty holes were produced on the chamber in 3 rows (each 20. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and effective factors were studied via side-by-side air sampling method. So, 48 clusters of samples were collected on polyvinyl chloride (PVC filters housed in sampling cassettes. Cassettes were located in 35, 50, and 65 cm above the solution surface with less than 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed according to the NIOSH method 7600. According to the ANOVA test, no significant differences were observed between different sampling locations in side-by-side sampling (P=0.82 and between sampling heights and different samplers distances (P=0.86 and 0.86, respectively. However, there were notable differences between means of coefficient of variations (CV in various heights and distances. It is concluded that the most chromium mist homogeneity could be obtained at height 50 cm from the bath solution surface and samplers distance of < 7.5 cm.

  1. Self-standing nanoribbons of antimony selenide and antimony sulfide with well-defined size and band gap

    Energy Technology Data Exchange (ETDEWEB)

    Vadapoo, Rajasekarakumar; Krishnan, Sridevi; Yilmaz, Hulusi [Department of Physics, University of Puerto Rico, San Juan, PR 00936 (Puerto Rico); Marin, Carlos [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States)

    2011-04-29

    Sub-10 nm semiconducting nanostructures are crucial for the realization of nanoscale devices. Fabrication of nanostructures at this scale with homogeneous properties is challenging. Using ab initio calculations, we show that self-standing ribbons of antimony selenide and antimony sulfide of width 1.1 nm exhibit well-defined bandgaps of 1.66 and 2.16 eV, respectively. Molecular dynamics studies show that these ribbons are stable at 500 K. The one-dimensional (1D) heterostructure of these nanoribbons (Sb{sub 2}Se{sub 3}/Sb{sub 2}S{sub 3}) along the [001] direction shows a straddling type behavior.

  2. The Non-Isotypical Nitride Selenides Dy3NSe3 and Ho3NSe3: Chains and Dimers

    OpenAIRE

    Lissner, Falk; Schleid, Thomas

    2009-01-01

    Abstract The non-isotypical lanthanoid(III) nitride selenides M3NSe3 of dysprosium (Dy3NSe3) and holmium (Ho3NSe3) are formed by the reaction of the respective rare-earth metal (M = Dy and Ho) with sodium azide (NaN3), selenium and an excess of iodine at 900 ?C from torch-sealed evacuated silica ampoules within seven days. Dy3NSe3 crystallizes orthorhombically (a = 1245.38(9), b = 393.69(3), c = 1303.74(9) pm) in space group Pnma with Z = 4, whereas monoclinic Ho3NSe3 (a = 1152.93(...

  3. Vacancies ordered in screw form (VOSF) and layered indium selenide thin film deposition by laser back ablation

    International Nuclear Information System (INIS)

    Indium selenide thin films are important due to their applications in non-volatile memory and solar cells. In this work, we present an initial study of a new application of deposition-site selective laser back ablation (LBA) for making thin films of In2Se3. Invacuo annealing and subsequent characterization of the films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that control of substrate temperature during deposition and post-deposition annealing temperature is critical in determining the phase and composition of the films. The initial laser fluence and target film thickness determine the amount of material deposited onto the substrate.

  4. Fluorescence imaging technology (FI) for high-throughput screening of selenide-modified nano-TiO2 catalysts.

    Science.gov (United States)

    Wang, Liping; Lee, Jianchao; Zhang, Meijuan; Duan, Qiannan; Zhang, Jiarui; Qi, Hailang

    2016-02-18

    A high-throughput screening (HTS) method based on fluorescence imaging (FI) was implemented to evaluate the catalytic performance of selenide-modified nano-TiO2. Chemical ink-jet printing (IJP) technology was reformed to fabricate a catalyst library comprising 1405 (Ni(a)Cu(b)Cd(c)Ce(d)In(e)Y(f))Se(x)/TiO2 (M6Se/Ti) composite photocatalysts. Nineteen M6Se/Tis were screened out from the 1405 candidates efficiently. PMID:26777131

  5. Analysis on the Performance of Copper Indium Gallium Selenide (CIGS Based Photovoltaic Thermal

    Directory of Open Access Journals (Sweden)

    Zulkepli Afzam

    2016-01-01

    Full Text Available This paper deals with the efficiency improvement of Copper Indium Gallium Selenide (CIGS Photovoltaic (PV and also solar thermal collector. Photovoltaic thermal (PV/T can improve overall efficiency for PV and also solve the problem of limited roof space at urban area. Objective of this study is to clarify the effect of mass flow rate on the efficiency of the PV/T system. A CIGS solar cell is used with rated output power 65 W and 1.18 m2 of area. 4 set of experiments were carried out, which were: thermal collector with 0.12 kg/s flow rate, PV/T with 0.12 kg/s flow rate, PV/T with 0.09 kg/s flow rate and PV. It was found that PV/T with 0.12 kg/s flow rate had the highest electrical efficiency, 2.92 %. PV/T with 0.09 kg/s flow rate had the lowest electrical efficiency, 2.68 %. It also had 2 % higher overall efficiency. The efficiency gained is low due to several factors. The rated output power of the PV is low for the area of 1.18 m2. The packing factor of the PV also need to be considered as it may not be operated at the optimal packing factor. Furthermore, aluminium sheet of the PV may affect the PV temperature due to high thermal conductivity. Further study on more values of mass flow rate and also other parameters that affect the efficiency of the PV/T is necessary.

  6. Formation of dimethyl selenide and trimethylselenonium from selenobetaine in the rat

    International Nuclear Information System (INIS)

    The 24-h respiratory excretion of dimethyl selenide (DMSe) and urinary excretion of trimethylselenonium (TMSe) were studied in adult male rats injected with 2 mg Se/kg as selenobetaine [(CH3)2Se+CH2COOH] or its methyl ester, labeled with 75Se and 14C. The DMSe was trapped by means of 20% benzyl chloride in xylene. TMSe was measured by cation exchange high performance liquid chromatography. There was extensive respiratory excretion of DMSe from selenobetaine methyl ester (about 50% of the dose) and from selenobetaine (about 25%). About 12% of the dose was converted to TMSe for both compounds. When the Se-methyl carbons were labeled with 14C and the selenium with 75Se, doubly labeled DMSe and TMSe were formed; the 14C/75Se ratio in DMSe formed from selenobetaine methyl ester was almost unchanged from that administered, and the ratio in TMSe was only slightly lower than in DMSe. In contrast to its ester, doubly labeled selenobetaine yielded DMSe having a lower 14C/75Se ratio (approximately one-half of that administered) and a further decrease was observed between DMSe and TMSe. These data indicate that the (CH3)2Se moiety in selenobetaine methyl ester undergoes facile release to form DMSe, which is directly methylated to form TMSe. Selenobetaine, however, appears to lose a methyl group prior to scission of the Se-CH2COOH bond. The results with selenobetaine also suggest that TMSe generated metabolically is not inert, and can undergo demethylation followed by remethylation; confirmatory evidence for this metabolic instability is provided by the exhalation of [75Se]DMSe after the direct administration of [75Se]TMSe. When [75Se]selenobetaine or its ester was given with the methylene carbon in the acetic acid molabeled with 14C, only 75Se was present in the DMSe and TMSe

  7. Exploring the doping effects of copper on thermoelectric properties of lead selenide

    Science.gov (United States)

    Gayner, Chhatrasal; Sharma, Raghunandan; Mallik, Iram; Das, Malay K.; Kar, Kamal K.

    2016-07-01

    In this work, we have explored the effect of dopant concentration (copper (Cu)) on the thermoelectric performance of Cu doped lead selenide (Pb1‑x Cu x Se (0  ⩽  x  ⩽  0.1)). With increasing the dopant concentration, sign inversion of majority charge carriers takes place for x  ⩾  0.04 due to the donor behaviour of Cu in the P-type pristine PbSe. The room temperature Seebeck coefficients of Pb1‑x Cu x Se with x  =  0.01, 0.02, 0.04, 0.06 and 0.08 are observed to be 233, 337, ‑473.7, ‑392.5 and  ‑257.6 μV K‑1, respectively as compared to that of 186.4 μV K‑1 of the pristine PbSe. This increment in Seebeck coefficient is the result of low carrier concentration and is not related to the resonance states created by Cu dopant. At room temperature, the lattice thermal conductivity of pristine PbSe is 0.52 W m‑1 K‑1 while for Cu doped PbSe, it varies from 0.8 to 1.1 W m‑1 K‑1. Finally, with ZT of ~0.59 and power factor of ~700 at 500 K, Pb0.98Cu0.02Se exhibits the highest thermoelectric performance among the studied Pb1‑x Cu x Se systems. Owing to the high ZT and power factor, a single thermoelement of Pb0.98Cu0.02Se exhibits thermovoltage of  >100 mV at a temperature gradient of 200 °C.

  8. Chromium supplementation improved post-stroke brain infarction and hyperglycemia.

    Science.gov (United States)

    Chen, Wen-Ying; Mao, Frank Chiahung; Liu, Chia-Hsin; Kuan, Yu-Hsiang; Lai, Nai-Wei; Wu, Chih-Cheng; Chen, Chun-Jung

    2016-04-01

    Hyperglycemia is common after acute stroke and is associated with a worse outcome of stroke. Thus, a better understanding of stress hyperglycemia is helpful to the prevention and therapeutic treatment of stroke. Chromium is an essential nutrient required for optimal insulin activity and normal carbohydrate and lipid metabolism. Beyond its nutritional effects, dietary supplement of chromium causes beneficial outcomes against several diseases, in particular diabetes-associated complications. In this study, we investigated whether post-stroke hyperglycemia involved chromium dynamic mobilization in a rat model of permanent focal cerebral ischemia and whether dietary supplement of chromium improved post-stroke injury and alterations. Stroke rats developed brain infarction, hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Post-stroke hyperglycemia was accompanied by elevated secretion of counter-regulatory hormones including glucagon, corticosterone, and norepinephrine, decreased insulin signaling in skeletal muscles, and increased hepatic gluconeogenesis. Correlation studies revealed that counter-regulatory hormone secretion showed a positive correlation with chromium loss and blood glucose increased together with chromium loss. Daily chromium supplementation increased tissue chromium levels, attenuated brain infarction, improved hyperglycemia, and decreased plasma levels of glucagon and corticosterone in stroke rats. Our findings suggest that stroke rats show disturbance of tissue chromium homeostasis with a net loss through urinary excretion and chromium mobilization and loss might be an alternative mechanism responsible for post-stroke hyperglycemia. PMID:26477944

  9. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

    2014-12-01

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

  10. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    International Nuclear Information System (INIS)

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr2O3 layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr2O3 layer. The α-Cr2O3 layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%

  11. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    Science.gov (United States)

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept. PMID:20031309

  12. Inelastic Scattering of Neutrons in Chromium

    International Nuclear Information System (INIS)

    The phonon spectrum of chromium has been studied by neutron inelastic scattering. The dispersion curves are very similar, in form to those of tungsten and molybdenum, indicating similar interionic force constants. The neutron groups broaden but do not shift appreciably when the temperature is raised. No effect has been observed which can be attributed to the interaction between the phonons and the crystal magnetization in the antiferromagnetic phase. (author)

  13. Observational Approach to Chromium Site Remediation - 13266

    International Nuclear Information System (INIS)

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the observational

  14. Stainless chromium-nickel steels. Chapter I

    International Nuclear Information System (INIS)

    The chemical composition is tabulated of 90 chromium-nickel stainless steels and alloys given in volume %. The values are also given of the corrosion resistance of the steels and alloys. The tables show data on the surface condition or the methods of material working, types and chemical composition of the medium where corrosion resistance tests were carried out, temperature, pressure, time of tests, corrosion rates, corrosion types, and literature references. A total of 35 references is given. (J.B.)

  15. Loading chromium atoms in a magnetic guide

    OpenAIRE

    Greiner, A; Sebastian, J.; Rehme, P.; Aghajani-Talesh, A.; Griesmaier, A.; Pfau, T.

    2007-01-01

    We have realized a magnetic guide for ultracold chromium atoms by continuously loading atoms directly from a Zeeman slower into a horizontal guide. We observe an atomic flux of $2 \\cdot 10^7$ atoms/s and are able to control the mean velocity of the guided atoms between 0 m/s and 3 m/s. We present our experimental results on loading and controlling the mean velocity of the guided atoms and discuss the experimental techniques that are used.

  16. X-616 Chromium Sludge Lagoons pictorial overview, Piketon, Ohio

    International Nuclear Information System (INIS)

    The Portsmouth Gaseous Diffusion Plant uses large quantities of water for process cooling. The X-616 Liquid Effluent Control Facility was placed in operation in December 1976 to treat recirculation cooling water blowdown from the process cooling system. A chromium-based corrosion inhibitor was used in the cooling water system. A chromium sludge was produced in a clarifier to control chromium levels in the water. Chromium sludge produced by this process was stored in two surface impoundments called the X-616 Chromium Sludge Lagoons. The sludge was toxic due to its chromium concentration and therefore required treatment. The sludge was treated, turning it into a sanitary waste, and buried in an Ohio EPA approved landfill. The plant's process cooling water system has changed to a more environmentally acceptable phosphate-based inhibitor. Closure activities at X-616 began in August 1990, with all construction activities completed in June 1991, at a total cost of $8.0 million

  17. Chromium oxidation state mapping in human cells

    Science.gov (United States)

    Ortega, R.; Fayard, B.; Salomé, M.; Devès, G.; Susini, J.

    2003-03-01

    The widespread use of chromium in industrial applications such as chemical production of pigments, refractory brick production, tanning, metallurgy, electroplating, and combustion of fuels has lead to human occupational exposure and to its increased introduction into the environment. Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation is not known. Up to now, no microanalytical technique was sensitive enough to allow the observation of chromium distribution, and oxidation state identification, within isolated cells at carcinogenic concentrations. In this experiment, we used successfully the ID-21 X-ray microscope to map Cr(VI) and total Cr distributions in cells exposed in vitro to soluble, and insoluble, Cr(VI) compounds. Exposure to soluble compounds, weak carcinogens, resulted in a homogeneous intracellular distribution of Cr, confirming by in situ measurement that Cr is present in the cell nucleus. Cr(VI) was never detected in cells which suggests a mechanism of rapid intracellular reducticn. On the other hand, exposure to insoluble compounds, strong carcinogens, also resulted in a homogeneous distribution of reduced forms of Cr in cells, and their nucleus. However, in this case, Cr(VI)-rich structures were observed into the cells suggesting that carcinogenicity is enhanced when oxidation reactions due to Cr(VI) chronic exposure are associated to Cr-DNA alterations.

  18. Dimensionally Controlled Lithiation of Chromium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fister, Tim T. [Argonne National Lab. (ANL), Argonne, IL (United States); Hu, Xianyi [Northwestern Univ., Evanston, IL (United States); Esbenshade, Jennifer [Univ. of Illinois, Urbana-Champaign, IL (United States); Chen, Xiao [Northwestern Univ., Evanston, IL (United States); Wu, Jinsong [Northwestern Univ., Evanston, IL (United States); Dravid, Vinayak [Northwestern Univ., Evanston, IL (United States); Bedzyk, Michael [Northwestern Univ., Evanston, IL (United States); Long, Brandon [Argonne National Lab. (ANL), Argonne, IL (United States); Gewirth, Andrew A. [Univ. of Illinois, Urbana-Champaign, IL (United States); Shi, Bing [Argonne National Lab. (ANL), Argonne, IL (United States); Schlepütz, Christian M. [Argonne National Lab. (ANL), Argonne, IL (United States); Fenter, Paul [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-12

    Oxide conversion reactions are an alternative approach for high capacity lithium ion batteries but are known to suffer from structural irreversibility associated with the phase separation and reconstitution of reduced metal species and Li2O. In particular, the morphology of the reduced metal species is thought to play a critical role in the electrochemical properties of a conversion material. Here we use a model electrode with alternating layers of chromium and chromium oxide to better understand and control these phase changes in real-time and at molecular length scales. Despite lacking crystallinity at the atomic scale, this superstructure is observed (with X-ray reflectivity, XR) to lithiate and delithiate in a purely one-dimensional manner, preserving the layered structure. The XR data show that the metal layers act as nucleation sites for the reduction of chromium in the conversion reaction. Irreversibility during delithiation is due to the formation of a ternary phase, LiCrO2, which can be further delithiated at higher potentials. The results reveal that the combination of confining lithiation to nanoscale sheets of Li2O and the availability of reaction sites in the metal layers in the layered structure is a strategy for improving the reversibility and mass transport properties that can be used in a wide range of conversion materials.

  19. Chromium--a material for fusion technology

    International Nuclear Information System (INIS)

    Due to their low neutron-induced radioactivity chromium based materials are considered to be candidates for structure materials in fusion technology. In this paper investigations are presented of unirradiated chromium with a purity of 99.96% (DUCROPUR) and a dispersion strengthened chromium alloy Cr5Fe1Y2O3 (DUCROLLOY). Both materials have been produced in a powder metallurgical route. Mechanical tests of smooth and pre-cracked specimens have been performed in a wide temperature range. Below 280 deg. C the fracture toughness values of DUCROPUR are very low (1/2), above the transition temperature they exceed 500 MPa m1/2. Large plastic deformations have been observed. DUCROLLOY does not indicate such a significant increase of fracture toughness in the tested temperature range. But above 400 deg. C large plastic deformations can be obtained in bending samples, too. The fatigue crack propagation behaviour of DUCROPUR at 300 deg. C is similar to that of a ductile metal

  20. Growth and evaluation of nonlinear optical crystals for laser applications: Lithium borate, barium borate and silver gallium selenide

    Science.gov (United States)

    Feigelson, Robert S.; Route, Roger K.

    1994-12-01

    This report summarizes a four year program on the development of high efficiency nonlinear optical materials. Major achievements were the development of effective top-seeded solution growth techniques for beta-barium borate (BBO) and lithium triborate (LBO). BBO crystals were also grown for the first time in the US by the direct melt growth technique, a metastable method that leads to significantly higher growth rates than the commercial solution-growth technique. High quality crystals were made available for optical property determinations and nonlinear optical device development at government and commercial laboratories. Additional accomplishments involved development of an optimum heat-treatment technology for eliminating optical scattering centers from as-grown crystals of silver gallium selenide. Cooperative programs were carried out with NRL to quantify the effects of intrinsic and extrinsic defects on residual absorption. It was discovered that silver gallium selenide and silver gallium sulfide crystals grown from silver-rich solutions are free of anomolous absorption in the 2 micron waveband which is currently the major problem limiting generation of high intensity, tunable 3-5 micron radiation by OPO methods using these materials. A new nonlinear optical material, (La,Gd)Sc3(BO3)4 has been identified for future study.

  1. A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

    OpenAIRE

    Inga Zinicovscaia

    2012-01-01

    Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The main source of chromium pollution including the Republic o Moldova is industry. It is a great need to develop new eco-friendly methods of chromium removal. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. This article is an extended abstract of a communication presented at the...

  2. CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.)

    OpenAIRE

    A. Chidambaram ، P. Sundaramoorthy ، A. Murugan ، K. Sankar Ganesh ، L. Baskaran

    2009-01-01

    Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations (0, 10, 25, 50, 100 and 200 mg/L) of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper). The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such...

  3. Processes affecting the remediation of chromium-contaminated sites.

    OpenAIRE

    Palmer, C.D.; Wittbrodt, P R

    1991-01-01

    The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitat...

  4. Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

    International Nuclear Information System (INIS)

    The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

  5. Production of a chromium Bose-Einstein condensate

    OpenAIRE

    Griesmaier, Axel; Stuhler, Jürgen; Pfau, Tilman

    2005-01-01

    The recent achievement of Bose-Einstein condensation of chromium atoms [1] has opened longed-for experimental access to a degenerate quantum gas with long-range and anisotropic interaction. Due to the large magnetic moment of chromium atoms of 6 {$\\mu$}B, in contrast to other Bose- Einstein condensates (BECs), magnetic dipole-dipole interaction plays an important role in a chromium BEC. Many new physical properties of degenerate gases arising from these magnetic forces have been predicted in ...

  6. Removal of chromium(VI) from saline wastewaters by

    OpenAIRE

    AKSU, Zümriye

    2002-01-01

    Some industrial wastewaters contain higher quantities of salts besides chromium(VI) ions so the effect of these salts on the biosorption of chromium(VI) should be investigated. The biosorption of chromium (VI) from saline solutions on two strains of living Dunaliella algae were tested under laboratory conditions as a function of pH, initial metal ion and salt (NaCl) concentrations in a batch system. The biosorption capacity of both Dunaliella strains strongly de...

  7. Increase of chromium utilization in stainless steel melting

    International Nuclear Information System (INIS)

    The processes of deoxidizing when melting stainless 18-10 steels in electric are furnaces by the method of remelting with wastes are investigated. The dependences of amount of reduced chromium on silicon consumption are made more precise. It is shown that it is useful to apply aluminium for deoxidation of acid high-chromium slags. Based on the data on pilot melts the extent to which aluminium can be used as a reducing agent for chromium is estimated. 3 refs., 2 figs

  8. Scientific Opinion on ChromoPrecise® cellular bound chromium yeast added for nutritional purposes as a source of chromium in food supplements and the bioavailability of chromium from this source

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)

    2012-01-01

    The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of ChromoPrecise® cellular bound chromium yeast added for nutritional purposes as a source of chromium in food supplements and the bioavailability of chromium from this source. ChromoPrecise® is a yeast preparation with an enriched trivalent chromium content, obtained by culture of Saccharomyces cerevisiae in the presence of chromium chloride. A daily intake of 100 µg ch...

  9. Chromium depletion from stainless steels during vacuum annealing

    International Nuclear Information System (INIS)

    The behaviour of chromium during selective evaporation by high temperature vacuum annealing has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that the rate of chromium loss from austenitic stainless steels 316 and 321 is controlled by chromium inter-diffusion rather than tracer diffusion in the alloy. Two important parameters in selective removal of chromium from alloy steels are the variation in the chromium surface concentration with time and the depletion profile in the alloy. The present work gives support for the model in which loss of chromium is dependent on its diffusivity in the alloy and on an interface transfer coefficient. The results showed that the surface concentration of chromium decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in accord with the previous derived model, apart from an anomalous near surface region. Here the higher resolution of a neutron activation technique indicated a region within approximately 2 microns of the surface where the chromium concentration decreased more steeply than expected. (author)

  10. Stabilization and solidification of chromium-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  11. Method of trivalent chromium concentration determination by atomic spectrometry

    Science.gov (United States)

    Reheulishvili, Aleksandre N.; Tsibakhashvili, Neli Ya.

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  12. Tribological Characteristics of Chromium-active Carbon Electroplated Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    GUKa-fi; HUAMeng; Yi-min

    2004-01-01

    A process of chromium electroplating using a standard bath with additives and active carbon particles was reported, and the tribological behaviors of the composite coatings using the pin-on-disk tester and the table wear tester were i nvestig(aed. Experimental results indicate that the electroplated chromium-active carbon composite coatings exhibited the low friction coefficient anti excellent anti-wear properties whets coffered with the normal chromium electroplated ones. The formation of active carbon particles within the chromium matrices can be explained by SEM analysis and the mechanis of wear resistance of the composite coatings were studied.

  13. Defect transformation in GSGG crystals during chromium ion activation

    International Nuclear Information System (INIS)

    Absorption and induced absorption spectra, dose dependence of induced absorption, thermoluminescence of GSGG crystals, nominally pure and activated with chromium and neodymium ions in different concentrations, are investigated. It is shown that it is chromium ion presence in large concentration that decreases the induced coloration in GSGG crystals after γ-irradiation at 300 K. Optimum concentration of chromium ions for the minimum of induced coloration are found. The mechanism of decrease of induced coloration consisting in Fermi level displacement by chromium ion activation is established. Defect concentration and localization and recombination possibilities of electrons and holes in GSGG crystals are estimated by computer simulation

  14. Oral bioavailability of chromium from a specific site.

    OpenAIRE

    Witmer, C M; Harris, R.; Shupack, S I

    1991-01-01

    Analysis of soil from a specific site in New Jersey indicated a low level of sodium and chromium present as a calcium compound. Chromium was then administered orally to young, mature male rats at a level of 240 micrograms/kg for 14 days as chromium-contaminated soil, as CaCrO4, and as an equimolar mixture of the soil and calcium salts for 14 days. The rats were sacrificed 24 hr after the last dosing, and tissues were taken immediately for chromium analysis. Blood, muscle, and liver contained ...

  15. MICRO-SEGREGATION OF CHROMIUM IN Fe-Cr ALLOY

    OpenAIRE

    Igata, N.; Sato, S; ANDO, T.; H. Doi; Nishikawa, O.; Shibata, M.

    1984-01-01

    The objective of this investigation is to clarify the behavior of chromium atoms in iron-5at.% chromium alloy. When the specimens were quenched after soultion annealing at 1150°C for 1hr, FIM image was only a bright area, but when they were tempered from 450°C to 650°C, both bright areas and dark areas were observed in the FIM image. In these quenched specimens there was microsegregation of chromium atoms : In bright areas the chromium concentration was lower, and in dark areas it was higher ...

  16. Influence of Chelating Agents on Chromium Fate in Sediment

    Institute of Scientific and Technical Information of China (English)

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

    A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment.The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the removal of Cr(Ⅲ)by sediment from solutions and the inhibiting effect was in the order:citric acid>tartaric acid>EDTA,Salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.

  17. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    Science.gov (United States)

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Leisch, Jennifer; Taylor, Matthew; Stanbery, Billy J.

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  18. A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers

    NARCIS (Netherlands)

    Xu, M.; Wachters, A.J.H.; Deelen, J. van; Mourad, M.C.D.; Buskens, P.J.P.

    2014-01-01

    We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIG

  19. Analysing the chromium-chromium multiple bond using multiconfigurational quantum chemistry

    OpenAIRE

    Brynda, Marcin; Gagliardi, Laura; Roos, Björn O.

    2009-01-01

    This Letter discusses the nature of the chemical bond between two chromium atoms in different di-chromium complexes with the metal atoms in different oxidation states. Starting with the Cr diatom, with its formally sextuple bond and oxidation number zero, we proceed to analyse the bonding in some Cr(I)–Cr(I) XCrCrX complexes with X varying from F, to Phenyl, and Aryl. The bond distance in these complexes varies over a large range: 1.65–1.83 Å and we suggest explanations for these variations. ...

  20. The effect of chromium picolinate on serum cholesterol and apolipoprotein fractions in human subjects.

    OpenAIRE

    Press, R. I.; Geller, J.; Evans, G. W.

    1990-01-01

    Chromium has been implicated as a cofactor in the maintenance of normal lipid and carbohydrate metabolism. A deficiency of chromium results from diets low in biologically available chromium. Picolinic acid, a metabolite of tryptophan, forms stable complexes with transitional metal ions, which results in an improved bioavailability of the metal ion chromium. To determine whether or not chromium picolinate is effective in humans, 28 volunteer subjects were given either chromium tripicolinate (3...

  1. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Torres, Marcos R. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Velez, Christian; Zayas, Beatriz [Universidad Metropolitana, ChemTox Laboratory, School of Environmental Affairs (United States); Rivera, Osvaldo [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Arslan, Zikri [Jackson State University, Department of Chemistry (United States); Gonzalez-Vega, Maxine N. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo [University of Puerto Rico, Molecular Science Research Center (United States); Primera-Pedrozo, Oliva M., E-mail: oprimera1@suagm.edu [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States)

    2015-06-15

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd{sup 2+}]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to

  2. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    International Nuclear Information System (INIS)

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd2+]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate

  3. The Effect of Chromium Added into Basal Diet on Serum Total Protein, Urea, Triglyceride, Cholesterol and Serum and Tissue Chromium, Zinc, Copper Levels in Rabbits

    OpenAIRE

    *, Kâzim ŞAHİN; *, Talat GÜLER; +, N. ŞAHİN; *, O. N. ERTAS; +, N. ERKAL

    1999-01-01

    This study was conducted to determine the effect of supplemantal dietary chromium on serum total protein, urea, triglycerides, cholesterol, and serum and tissue chromium, zinc, and copper contents of pregnant rabbits, their offspring and their young rabbits. Treatment groups consisted of chromium level as follows: Control Group no supplementation chromium into basal diet, Treatment I (200 ppb Group) contained 200 ppb of supplemental chromium into basal diet, and Treatment II (400 ppb Group...

  4. STABILITY AND ABSORPTION OF CHROMIUM AND ABSORPTION OF CHROMIUM HISTIDINE BY HUMANS

    Science.gov (United States)

    Increased intake of chromium has been shown to lead to improvements in glucose, insulin, lipids, and related variables in studies involving humans, experimental and farm animals. However, the results are often variable depending not only upon the selection of subjects, but also dietary conditions a...

  5. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: • In4Se2.85@graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In4Se2.85 is notably changed upon the composite formation with graphene. • In4Se2.85@graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In4Se2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In4Se2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In4Se2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In4Se2.85. Both the nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In4Se2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In4Se2.85@graphene nanocomposite is superior to that of the In4Se2.85@carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In4Se2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence on the chemical bonds and electrode activity of indium

  6. Chromium and Polyphenols From Cinnamon Improve Insulin Sensitivity

    Science.gov (United States)

    Naturally occurring compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in cinnamon. These compounds also have similar effects on insulin signaling and glucose control. The signs of chromium deficiency are similar to those for the metabolic syndrome ...

  7. IRIS Toxicological Review of Hexavalent Chromium (2010 External Review Draft)

    Science.gov (United States)

    [UPDATE] New Schedule for IRIS Hexavalent Chromium Assessment In Feb 2012, EPA developed a new schedule for completing the IRIS hexavalent chromium assessment. Based on the recommendations of the external peer review panel, which met in May 2011 to review the dra...

  8. Composition and structure of plasma sprayed chromium steel powders

    Czech Academy of Sciences Publication Activity Database

    Schneeweiss, O.; Voleník, Karel; Kolman, Blahoslav Jan

    Praha, 2005, s. 105-111. ISBN 1899072 18 7. [EURO Powder Metallurgy Congress & Exhibition. Prague (CZ), 02.10.2005-05.10.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : chromium steel * plasma spraying * chromium depletion * Mössbauer spectroscopy Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  9. Safety, absorption, and antioxidant effects of chromium histidine

    Science.gov (United States)

    Supplemental chromium has been shown to be involved in the alleviation of the metabolic syndrome, glucose intolerance, polycystic ovary syndrome, depression, excess body fat, and gestational, steroid-induced, and type 2 diabetes. Chromium amino acid complexes that contained histidine displayed cons...

  10. Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination.

    Science.gov (United States)

    Sánchez-Fortún, Sebastián; López-Rodas, Victoria; Navarro, Macarena; Marvá, Fernando; D'ors, Ana; Rouco, Mónica; Haigh-Florez, David; Costas, Eduardo

    2009-09-01

    Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals. Because the mechanisms allowing heavy metal tolerance of algae are not yet known, the present study analyzed the effect of hexavalent chromium on growth and photosynthetic performance of Dictyosphaerium chlorelloides, stressing on the adaptation mechanisms to chromium contamination. Growth and photosynthetic performance of algal cells were inhibited by Cr(VI) at 10 mg/L, and the 72-h median inhibition concentration was established as 1.64 and 1.54 mg/L, respectively. However, after further incubation for a three month period in an environment with 25 mg/L of chromium, some rare, chromium-resistant cells occasionally were found. A Luria-Delbrück fluctuation analysis was performed to distinguish between resistant algae arising from rare, spontaneous mutations and resistant algae arising from physiological adaptation and other adaptive mechanisms. Resistant cells arose only by spontaneous mutations before the addition of chromium, with a rate of 1.77 x 10(-6) mutants per cell division. From a practical point of view, the use of both chromium-sensitive and chromium-resistant genotypes could make possible a specific algal biosensor for chromium. PMID:19323601

  11. Residual Chromium in Leather by Instrumental Neutron Activation Analysis

    Directory of Open Access Journals (Sweden)

    S. Okoh

    2012-01-01

    Full Text Available Problem statement: Most tanning processes employ the use of chromium sulphate. For chromium tanned leather, finished products may contain high amount of residual chromium. This may pose some health hazards, since chromium is known to be toxic at elevated concentration. This justifies the need for the study. Approach: Various samples of leather were collected from a tannery, a leather crafts market, a leather dump site and from local tanners all in Kano, Nigeria in 2009. The samples were irradiated for 6 h in the inner site of the Nigerian Research Reactor (NIRR-1 at a flux of 5×1011 ncm-2 sec-1. Results: After evaluating the spectrum, the mean results for chromium in the samples were determined as 2.33±0.3, 2.23±0.3 and 2.93±0.4% for samples from the tannery, leather crafts market and leather dump sites respectively. Chromium concentration in samples collected from local tanners who use tannins from Acacia nilotica as tanning agent was below the detection limit of Instrumental Neutron Activation Analysis (INAA technique used in the study. Conclusion: Although, the concentrations of chromium in the analysed samples were not much higher than what were obtained in literature, they may be enough to sensitize the population that is allergic to chromium.

  12. AMORPHOUS ALLOY SURFACE COATINGS FOR HARD CHROMIUM REPLACEMENT - PHASE I

    Science.gov (United States)

    Hard chromium coatings (0.25 to10 mil thick) are used extensively for imparting wear and erosion resistance to components in both industrial and military applications. The most common means of depositing hard chromium has been through the use of chromic acid baths containing ...

  13. ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    NESHEM DO; RIDDELLE J

    2012-01-30

    At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a weak base anion single-use resin, ResinTech SIR-700, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently on site, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation and return of resin for regeneration. This resin was installed in Hanford's newest groundwater treatment facility, called 100-DX, which began operations in November, 2010, and used in a sister facility, 100-HX, which started up in September of 2011. This increased chromium treatment capacity to 25 trains (100 vessels). The resin is also being tested in existing facilities that utilize Dowex 21 K for

  14. Chromium-Makes stainless steel stainless

    Science.gov (United States)

    Kropschot, S.J.; Doebrich, Jeff

    2010-01-01

    Chromium, a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point, is a silvery white, hard, and bright metal plating on steel and other material. Commonly known as chrome, it is one of the most important and indispensable industrial metals because of its hardness and resistance to corrosion. But it is used for more than the production of stainless steel and nonferrous alloys; it is also used to create pigments and chemicals used to process leather.

  15. The electronic structure of antiferromagnetic chromium

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1981-01-01

    The author has used the local spin density formalism to perform self-consistent calculations of the electronic structure of chromium in the non-magnetic and commensurate antiferromagnetic phases, as a function of the lattice parameter. A change of a few per cent in the atomic radius brings...... the calculated ground state properties into agreement with experiment. The magnetisation is studied as function of volume in several models, and it is shown that a Stoner picture provides an extremely accurate description of the full calculation provided the sp-d hybridisation is taken into account. It is found...

  16. Effects of UV light and chromium ions on wood flavonoids

    International Nuclear Information System (INIS)

    The individual and simultaneous effect of UV light and chromium ions was investigated by spectrophotometric methods on inert surfaces impregnated with quercetin or robinetin. The UV-VIS spectra of the silica gel plates impregnated with these flavonoids were modified characteristically after irradiating ultraviolet light. Even a half an hour of irradiation has caused irreversible changes in the molecule structure. A certain chemical - presumably complexation - was concluded from the change of spectral bands assigned to flavonoids when impregnated with chromic ions. Hexavalent chromium caused more complex changes in the absorption spectra. The differences in the spectra could indicate either the oxidation and decomposition of flavonoids, or some kind of coordination process and the reduction of hexavalent chromium. The simultaneous application of UV light and chromium ions caused more pronounced effects. The complexation process between chromium(III) and flavonoid was completed

  17. CHROMIUM BIOACCUMULATION FROM COMPOSTS AND VERMICOMPOSTS BASED ON TANNERY SLUDGES

    Directory of Open Access Journals (Sweden)

    Krzysztof GONDEK

    2008-07-01

    Full Text Available Storage of waste substances is not indifferent to ecological equilibrium in the environment therefore should not be the ultimate way to limit waste arduousness. Therefore, the conducted investigations aimed to determine the effect of tannery composts and vermicomposts loaded with chromium on this element bioaccumulation in earthworm bodies and biomass of selected plants. Chromium in composts and vermicomposts based on tannery sludges occurred in small quantities and easily soluble compounds. Chromium concentrations in redworm biomass points to this metal accumulation in Eisenia fetida body tissues. This element content in redworm biomass was signifi cantly positively correlated with its content in composts. Chromium content in plants was diversifi ed and on treatments was generally smaller than on mineral treatment or farmyard manure. Chromium absorbed by plants was stored mainly in the root systems, and over the norm content of this element found in vermicomposts did not cause its excessive accumulation in plant biomass.

  18. Biosorption potency of Aspergillus niger for removal of chromium (VI).

    Science.gov (United States)

    Srivastava, Shaili; Thakur, Indu Shekhar

    2006-09-01

    Aspergillus niger isolated from soil and effluent of leather tanning mills had higher activity to remove chromium. The potency of Aspergillus niger was evaluated in shake flask culture by absorption of chromium at pH 6 and temperature 30 degrees C. The results of the study indicated removal of more than 75% chromium by Aspergillus niger determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometry after 7 days. Study of microbial Cr(VI) reduction and identification of reduction intermediates has been hindered by the lack of analytical techniques that can identify the oxidation state with subcellular spatial resolution. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which indicated an accumulation of chromium in the fungal mycelium. PMID:16874547

  19. Specific features of the electrocrystallization of chromium together with molybdenum

    International Nuclear Information System (INIS)

    A study was made on molybdenum effect on surface structure and some physicomechanical properties of electrolytic chromium during Cr-Mo electrodeposition from CrO3 solutions with additions of SO42- and SiFe62- anions. Cr-Mo deposition was conducted at 55 deg C and 0.5 A/cm2 current density which corresponds to conditions of hard chromizing. It is shown that the change hardness, hydridation and internal stresses of chromium coatings during their alloying with molybdenum is conditioned by structure change. Mo introduction into chromium is not manifested clearly in these characteristics. The change of chromium structure during deposition with molybdenum is probably related both with change of anion relation in cathode film (decrease of catalytic anion content in it) and peculiarities of chromium electrocrystallization. This requires special study with application of methods for investigation into fine and surface structure

  20. Post-test analysis of components from selenide isotope generator modules M-7, M-15, and M-18

    International Nuclear Information System (INIS)

    Several critical components removed from SIG (Selenide Isotope Generator) thermoelectric modules M-7, M-15C, M-15D, and M-18 were examined. These modules failed to show the predicted stability and conversion efficiency. Understanding the degradation and identifying means for preventing it necessitated detailed post-test examinations of key parts in the modules. Steel springs, which provided pressure for contacts at the hot and cold ends of P- or N-legs, relaxed more than expected. Beryllium oxide insulators had dark deposits that caused electrical shorts. The GdSe149 N-leg exhibited cracking. The (Cu,Ag)2Se P-leg lost weight or sublimed excessively in module M-7 and more than expected in the other modules

  1. Post-test analysis of components from selenide isotope generator modules M-7, M-15, and M-18

    Energy Technology Data Exchange (ETDEWEB)

    Wei, G.C.; Keiser, J.R.; Crouse, R.S.; Allen, M.D.; Schaffhauser, A.C.

    1979-05-01

    Several critical components removed from SIG (Selenide Isotope Generator) thermoelectric modules M-7, M-15C, M-15D, and M-18 were examined. These modules failed to show the predicted stability and conversion efficiency. Understanding the degradation and identifying means for preventing it necessitated detailed post-test examinations of key parts in the modules. Steel springs, which provided pressure for contacts at the hot and cold ends of P- or N-legs, relaxed more than expected. Beryllium oxide insulators had dark deposits that caused electrical shorts. The GdSe/sub 1/ /sub 49/ N-leg exhibited cracking. The (Cu,Ag)/sub 2/Se P-leg lost weight or sublimed excessively in module M-7 and more than expected in the other modules.

  2. A novel polysaccharide isolated from mulberry fruits (Murus alba L.) and its selenide derivative: structural characterization and biological activities.

    Science.gov (United States)

    Chen, Chun; Zhang, Bin; Fu, Xiong; Liu, Rui Hai

    2016-06-15

    A novel polysaccharide (MFP3P) was isolated from Murus alba L. through the hot water extraction method followed by chromatographic purification. The chemical structure of MFP3P was elucidated by acid hydrolysis, Smith degradation and methylation analysis, along with FT-IR, GC-MS, (1)H and (13)C NMR spectroscopy. Its morphological properties were further characterized by SEM and AFM. The selenide of the polysaccharide (MFP3P-Se) was obtained by the Na2SeO3/BaCl2 method. The antioxidant properties showed that MFP3P-Se exhibited higher peroxy radical-scavenging capacity than MFP3P in vitro. Moreover, MFP3P-Se had more significant hypoglycemic effects than MFP3P through promoting pancreatic cell proliferation and increasing glucose metabolism and insulin secretion. PMID:27241036

  3. Cuprous Iodide Catalyzed Synthesis of Diaryl Selenide and Telluride from Organoboronic Acids with Diphenyl Diselenide and Ditelluride

    Institute of Scientific and Technical Information of China (English)

    WANG,Lei; WANG,Min; YAN,Jin-Can; LI,Pin-Hua

    2004-01-01

    @@ Organoselenium and tellurium compounds have received much attention not only as synthetic reagents or intermediates in organic synthesis but also as promising donor molecules for conductive materials.[1] A number of synthetic methods have been reported to prepare organoselenium and tellurium derivatives. A convenient and general method to introduce a selenium or tellurium moiety into organic molecules is the reaction of a metal selenolate or tellurolate with appropriate electrophiles such as organic halides, acyl chlorides, epoxides, and α, β-enones.[2] However, it is difficult to synthesize the unsymmetrical diarylselenides and tellurides through the reaction of selenide anion with organic halides because of the less reactivity of aryl halides. To accomplish this purpose, the reaction (iodobenzene with phenylselenol)was generally carried out in the presence of catalysts, ligands and strong bases. But, the reaction needs longer time to accomplish and form the products in moderate yields.

  4. Selenium protection from cadmium and chromium poisoning

    International Nuclear Information System (INIS)

    The interaction of selenium with cadmium and chromium was studied in 168 chicken-broilers (DWCxWR) divided into four equal groups. Eight-week old control animals received an intravenous dose of /sup 115m/Cd Chloride 370 KBq/Kg (Group I), or 51Cr Chloride 370 KBq/Kg (Group II). The kinetics of these isotopes were studied by scintillation spectrometry (NaI/TI) carried out for whole blood, plasma, plasma proteins, urine, feces and homogenates of all organs at various time intervals. Animals in Groups III and IV received eight subcutaneous doses of sodium selenate (5ug) at 8-week intervals prior to /sup 115m/Cd or 51Cr. The kinetics of these elements were studied as in the previous two groups. It was found that selenium affected those kinetics in two ways: (a) by increasing the excretion of Cd by 11 +/- 3% (P < 0.001) and that of Cr by 7 +/- 1% (P < 0.001); and (b) by favoring redistribution of those elements, with significant (P < 0.001) reductions in liver, endocrine glands and kidney and increases (P < 0.01) in bone. The study suggests that selenium protects the animals' vital organs from environmental pollutants, such as cadmium and chromium

  5. The hydrogen anode in chromium electrowinning

    International Nuclear Information System (INIS)

    The use of a hydrogen anode for electrowinning of chromium from an ammonium chromium sulfate electrolyte (chrome alum process) was investigated in a laboratory-scale cell equipped with a diaphragm. The composition of the solution and the temperature followed industrial practice. Current density, pH, and anolyte flow rate through the diaphragm were varied and optimized for the cell. For a cathodic current density of 915 A/m2 at 50oC, the optimum initial pH was 2.37. The hydrogen anode was made of a platinized Toray carbon paper (0.35 mg Pt per cm2) supplied by E-TEK. The hydrogen pressure was maintained at 2 cm H20 above ambient atmosphere. The potential of the hydrogen anode was about 1 V lower than that of a Pb-Ag anode (1%Ag) in a similar cell. As expected, no Cr+6 was generated in the anolyte. The cathodic current efficiency was slightly lower with the hydrogen anode than with the Pb-Ag anode. (author)

  6. Biliary excretion of chromium in the rat

    International Nuclear Information System (INIS)

    The relative amount of chromium excreted in rat bile after injection of Cr-III is much less than after injection of Cr-VI, about 0.1% and from 6-8% during 5 hours respectively, for corresponding dose levels. The liver to bile ratio was 50-100 for Cr-III injection for Cr-VI the ratio was 2-3. With doses up to 18 μmol Cr/kg, only Cr-III was found in bile even after injection of CR-VI.Glutathione depletion of the liver with cyclohexene oxide decreased chromium excretion in bile. Such treatment also decresed the reduction of Cr-VI to Cr-III in the liver cell as only Cr-VI was found in bile. A different distribution of Cr-III in the liver dependent on whether derived from Cr-VI or taken up by the liver as such must be assumed. Taking into account the usual low penetration of biological membranes by Cr-III, a possible active transport mechanism or a specific diffusable Cr-III compound must be postulated. (author)

  7. Workshop on effects of chromium coating on Nb3Sn superconductor strand: Proceedings

    International Nuclear Information System (INIS)

    This report discusses the following topics: Chromium coating on superconductor strand -- an overview; technology of chromium plating; comparison of wires plated by different platers; search for chromium in copper; strand manufactures' presentations; chromium plating at the Lawrence Livermore National Laboratory; a first look at a chromium plating process development project tailored for T.P.X. and I.T.E.R. strand; and influence of chromium diffusion and related phenomena on the reference ratios of bare and chromium plated Nb3Sn strand

  8. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Damir Barbir; Pero Dabić; Petar Krolo

    2012-12-01

    Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration. The microcalorimetrical results show that with increasing the share of chromium salt, heat maximums assume lower values and the occurrence of the maximum registered in the earlier hydration times. Conductometrical measurements show that with increasing addition of chromium salt, curve did not show any specific shape, immediate drop in specific conductivity is noticed and the maximum is reached earlier. This coincides with microcalorimetrical results. It can be concluded that the addition of chromium does not affect the mechanism of the hydration process, but it does affect the kinetic parameters and dynamics of the cement hydration process. It was found that chromium salt addition to the cement–water system is acceptable up to 2 wt.%. According to standard EN 196-3 for OPC, the beginning of binding time should occur after 60 minutes. Increased amount of chromium over 2 wt.% significantly accelerate the beginning of binding time and for the system it is not acceptable.

  9. Chromium speciation in rainwater: temporal variability and atmospheric deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry

    2002-12-15

    Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs.

  10. Bioavailability of a potato chromium complex to the laboratory rat

    International Nuclear Information System (INIS)

    Research objectives were to study the effect of food source, preparation method and chemical form on bioavailability of chromium. Chromium concentration in potatoes was determined and tubers labeled either intrinsically or extrinsically with radioactive chromate. A labeled chromium complexes was isolated from preparations of raw, baked or fried potatoes and chromatographed on gel permeation media. Availability of the potato chromium complex to the rat was examined in three feeding studies. Animals were dosed with radioactive extrinsically or intrinsically labeled potato extract or with chromate. A labeled chromium complex was isolated from gastrointestinal contents of rats and chromatographed. Potato pulp and peel contained 1.63 and 2.70 μg Cr/g tissue respectively. True and apparent absorption from extrinsically labeled feedings were 33.4 +/- 4.7 and 29.8 +/- 11.2% respectively, and no differences existed between absorption from raw and cooked potatoes. Absorption from the extrinsic labeled potatoes differed significantly from absorption of inorganic chromatium. Apparent absorption of raw (11.1 +/- 7.9%) and cooked (-0.7 +/- 2.8%) intrinsically labeled feedings differed significantly. Absorption of inorganic chromium was 17.8% (true) and 11.5% (apparent). Examination of the chromium complex isolated from gastrointestinal tract contents showed enlargement of the complex in the stomach after consumption

  11. Chromium-induced membrane damage: protective role of ascorbic acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80 - 100gbody weight). It has been observed that the intoxication with chromium ( i. p. ) at the dose of 0.8 mg/100g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospbolipid of both liver and kidney. The alkaline pbosphatase, total ATPase and Na + -K + -ATPase activities were significantly decreased in both liver and kidney after chromium treatment,except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid ( i.p. at the dose of 0.5 mg,/100g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium-induced membrane damage.

  12. Fertilizers and Mixed Crop Cultivation of Chromium Tolerant and Sensitive Plants under Chromium Toxicity

    OpenAIRE

    B. Dheeba; Sampathkumar, P; Kannan, K.

    2015-01-01

    Zea mays (maize) and Vigna radiata (green gram) are found to be the chromium (Cr) tolerant and sensitive plants, respectively. In the present paper, we investigate the reduction of the toxicity of Cr in the sensitive plants by the mixed crop cultivation in the field using various amendments. Further, the potassium dichromate was used as the source of hexavalent Cr. The results indicated that Cr adversely affects both the growth and yield of plants. The soil properties vary with Cr and differe...

  13. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria

    Science.gov (United States)

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L-1.

  14. Chromium removal from tannery wastewater by using of flying ash

    International Nuclear Information System (INIS)

    A simple and economic method to chromium removal from tannery wastewater by means of flying ash is presented. The chromium removal operation is a discontinuous process that involve the mass of flying ash, time of contact and temperature or ph as variables, their which are optimized through Box-Wilson type experimental design. The results were successful: From an initial fluid whit chromium concentration of 1850m ppm, final concentrations of 0.008 ppm and 0.5 ppm of Cr+3 and Cr+6 respectively were achieved. These post-treatment concentrations are into the approved range definite by Government's Laws to this waste type

  15. A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    Inga Zinicovscaia

    2012-12-01

    Full Text Available Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The main source of chromium pollution including the Republic o Moldova is industry. It is a great need to develop new eco-friendly methods of chromium removal. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. This article is an extended abstract of a communication presented at the Conference Ecological Chemistry 2012

  16. Thermal incorporation behavior during the reduction and stabilization of chromium wastes

    OpenAIRE

    Yang, Jun; 楊駿

    2015-01-01

    The possibility of employing periclase to stabilize chromium in chromium wastes into spinel-based ceramics through thermal method was investigated by heating mixture of simulated chromium waste and magnesium oxide. Different types of magnesium oxide precursors were introduced to incorporate chromium oxide into magnesiochromite (MgCr2O4) ranging from 550 ºC to 1350 ºC. Magnesium oxide precursors of both types can effectively incorporate chromium oxide but via different mechanisms. Three main f...

  17. Effects of Supplemental Dietary Chromium on Yield and Nutrient Digestibility of Laying Hens Under Low Temperature

    OpenAIRE

    ŞAHİN, Kazım; ERTAŞ, O. Nihat; GÜLER, Talat; ÇİFTÇİ, Mehmet

    2001-01-01

    This study was conducted to determine the effects of chromium picolinate (CrPi) added into diet containing 710.3 ppb chromium on yield and nutrient digestibility of laying hens at low temperature. Forty-six-week-old laying hens were randomly assigned to four groups of 30 hens per group. Treatment groups were fed different supplemental dietary chromium levels. Thus, hens were fed diets with no supplemental chromium (Control Group), 100 ppb of supplemental chromium (100 Group), 200 ppb of s...

  18. Evaluation of the comprehensiveness and reliability of the chromium composition of foods in the literature ☆

    OpenAIRE

    Thor, Mayly Y.; Harnack, Lisa; King, Denise; Jasthi, Bhaskarani; Pettit, Janet

    2011-01-01

    In the early 1960s, trivalent chromium Cr3+ became recognized as an essential trace element due to its potential metabolic and cardiovascular benefits. No comprehensive chromium database currently exists; thus a thorough review of the literature was conducted to examine the availability and reliability of chromium data for foods. A number of key issues were identified that challenge the feasibility of adding chromium to a food and nutrient database. Foremost, dietary chromium data reported in...

  19. Chromium(III) complexation to natural organic matter : Mechanisms and modeling

    OpenAIRE

    Gustafsson, Jon Petter; Persson, I.; Oromieh, A. G.; Van Schaik, J. W. J.; Sjöstedt, Carin; Kleja, D. B.

    2014-01-01

    Chromium is a common soil contaminant, and it often exists as chromium(III). However, limited information exists on the coordination chemistry and stability of chromium(III) complexes with natural organic matter (NOM). Here, the complexation of chromium(III) to mor layer material and to Suwannee River Fulvic Acid (SRFA) was investigated using EXAFS spectroscopy and batch experiments. The EXAFS results showed a predominance of monomeric chromium(III)-NOM complexes at low pH (<5), in which o...

  20. Abatement of Chromium Emissions from Steelmaking Slags - Cr Stabilization by Phase Separation

    OpenAIRE

    Albertsson, Galina

    2013-01-01

    Chromium is an important alloying element in stainless steel but also environmentally harmful element. A number of mineralogical phases present in the slag matrix can contain chromium and lead to chromium leaching. Chromium in slag if not stabilized, could oxidize to the cancerogenic hexavalent state, and leach out if exposed to acidic and oxygen rich environment. Other environmental concerns are slag dusting and chromium escape to the atmosphere. Despite the fact that there is a certain risk...

  1. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    OpenAIRE

    Arh, B.; F. Tehovnik

    2011-01-01

    The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming sla...

  2. Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

    Institute of Scientific and Technical Information of China (English)

    HUANG Shun-hong; PENG Bing; YANG Zhi-hui; CHAI Li-yuan; ZHOU Li-cheng

    2009-01-01

    The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.

  3. Evaluation of chromium in red blood cells as an indicator of exposure to hexavalent chromium: An in vitro study.

    Science.gov (United States)

    Devoy, Jérôme; Géhin, Antoine; Müller, Samuel; Melczer, Mathieu; Remy, Aurélie; Antoine, Guillaume; Sponne, Isabelle

    2016-07-25

    Chromium(VI) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and whole blood (i.e., including plasma) are indicative of recent exposure, chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure. Before recommending Cr in RBC as a biological indicator of Cr(VI) exposure, in-vitro studies must be undertaken to assess its reliability. The present study examines the relationship between the chromium added to a blood sample and that subsequently found in the RBC. After incubation of total blood with chromium, RBC were isolated, counted and their viability assessed. Direct analysis of chromium in RBC was conducted using Atomic Absorption Spectrometry. Hexavalent, but not trivalent Cr, was seen to accumulate in the RBC and we found a strong correlation between the Cr(VI) concentration added to a blood sample and the amount of Cr in RBC. This relationship appears to be independent of the chemical properties of the human blood samples (e.g., different blood donors or different reducing capacities). Even though in-vivo studies are still needed to integrate our understanding of Cr(VI) toxicokinetics, our findings reinforce the idea that a single determination of the chromium concentration in RBC would enable biomonitoring of critical cases of Cr(VI) exposure. PMID:27178267

  4. Crystal and electronic structures of two new iron selenides: Ba4Fe3Se10 and BaFe2Se4

    International Nuclear Information System (INIS)

    The new ternary selenides, Ba4Fe3Se10 and BaFe2Se4, were synthesized from a reaction of appropriate amounts of elements at high temperature in a silica sealed tube, and their structures were resolved using X-ray single crystal diffraction. BaFe2Se4 crystallizes in the tetragonal space group I4/m with a=8.008(9) Å and c=5.483(3) Å as cell parameters. It is a new compound with a structure isotypical to the sulfide BaFe2S4 which belongs to the infinitely adaptive structures series Ba1+xFe2S4. The second compound, Ba4Fe3Se10, crystallizes in the monoclinic space group P21/n with a=8.8593(1) Å, b=8.8073(1) Å, c=12.2724(1) Å and β=109.037(6)° as cell parameters. It exhibits an original structure with a new type of iron selenide polyhedra. These data were consistent with the powder X-ray diffraction and TEM analyses. Their electronic structures point towards metallicity and electronic correlations for both selenides. - Graphical abstract: Experimental [010] oriented ED pattern and corresponding HREM image of Ba4Fe3Se10. Image calculated with a focus and thickness to 15nm and 8 nm respectively is inserted. Bright contrasts are correlated to Se rows belonging to FeSe3(Se2)2−–FeSe6–FeSe3(Se2)2− trimers. The corresponding structure projection is also shown. - Highlights: • Two new barium iron selenide compounds. • An original structure type Ba4Fe3Se10. • Electronic structure calculations

  5. The fate of chromium during tropical weathering

    DEFF Research Database (Denmark)

    Berger, Alfons; Frei, Robert

    2014-01-01

    We performed a mineral, geochemical and Cr–Sr–Pb isotope study on a laterite profile developed on ca. 540 Ma old tonalitic bedrock in Madagascar with special emphasis on the behavior of chromium during tropical weathering. The observed strong depletions of Ca, Si, and P, and enrichment of Fe and Al...... weathering profile. The negatively fractionated δ53Cr values measured in the weathering profile relative to the unaltered tonalitic bedrock characterized by a high temperature magmatic inventory Cr isotope signature are consistent with loss of a positively fractionated Cr(VI) pool formed during weathering...... highly oxidative conditions, which in well drained sulfide-bearing parent bedrocks potentially lead to both, acid dissolution of sulfide-hosted Cr and redox-promoted mobilization of Cr(VI) from silicates during later stages of weathering under basic pH conditions....

  6. Neutron capture by the chromium isotopes

    International Nuclear Information System (INIS)

    Capture cross sections of the chromium isotopes have been measured at neutron energies up to 350 keV using the capture cross section facility at the 40 m station of the Oak Ridge Electron Linear Accelerator. Parameters have been derived for 180 resonances. A moderate correlation [rho(gamma-n-0,gamma-gamma) approximately 0.45] is observed between reduced neutron widths and radiative widths for s-wave resonances. Calculations of valence widths show that valence capture can only account for the correlated component of the observed radiative widths. An additional mechanism such as a 2p-1h doorway state must therefore be occurring to explain the uncorrelated component. (author)

  7. Synthesis and characterization of (Ni1-xCox)Se2 based ternary selenides as electrocatalyst for triiodide reduction in dye-sensitized solar cells

    Science.gov (United States)

    Theerthagiri, J.; Senthil, R. A.; Buraidah, M. H.; Raghavender, M.; Madhavan, J.; Arof, A. K.

    2016-06-01

    Ternary metal selenides of (Ni1-xCox)Se2 with 0≤x≤1 were synthesized by using one-step hydrothermal reduction route. The synthesized metal selenides were utilized as an efficient, low-cost platinum free counter electrode for dye-sensitized solar cells. The cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that the Ni0.5Co0.5Se2 counter electrode exhibited higher electrocatalytic activity and lower charge transfer resistance at the counter electrode/electrolyte interface than the other compositions for reduction of triiodide to iodide. Ternary selenides of Ni0.5Co0.5Se2 offer a synergistic effect to the electrocatalytic activity for the reduction of triiodide that might be due to an increase in active catalytic sites and small charge transfer resistance. The DSSC with Ni0.5Co0.5Se2 counter electrode achieved a high power conversion efficiency of 6.02%, which is comparable with that of conventional platinum counter electrode (6.11%). This present investigation demonstrates the potential application of Ni0.5Co0.5Se2 as counter electrode in dye-sensitized solar cells.

  8. Investigation of deep level defects in epitaxial semiconducting zinc sulpho-selenide. Progress report, 15 June 1979-14 June 1980

    International Nuclear Information System (INIS)

    In an effort to understand the defect structure of the ternary II-VI compound zinc sulpho-selenide, the binary compound zinc selenide was investigated. Thin single crystalline films of zinc selenide were heteroepitaxially grown on (100) GaAs. Epitaxial layers from 5 to 50 microns thick could be readily grown using a chemical vapor transport technique. The layers had an excellent morphology with few stacking faults and hillocks. Detailed epitaxial growth kinetics were examined as a function of temperature and reactant concentration. It was found that hydrogen flow rate, source and substrate temperature affect the growth rate of the epitaxial films. Au - ZnSe Schottky barrier diodes and ZnSe - GaAs n-p heterojunctions were prepared from the epitaxial layers. Current-voltage characteristics were measured on both types of diodes. From capacitance-voltage measurements the residual doping density of the epitaxial layers were found to be of the order of 1014 - 1015 cm-3. Finally, we have begun to measure the deep level spectrum of both the Schottky barrier diodes and the heterojunctions. Deep level transient spectroscopy appears to be well suited for determining trapping states in ZnSe provided the material has a low enough resistivity

  9. Chromium and Polyphenols from Cinnamon and Insulin Sensitivity

    Science.gov (United States)

    Factors that improve insulin sensitivity usually lead to improvements in risk factors associated with the metabolic syndrome, diabetes, and cardiovascular diseases. Naturally occurring bioactive compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in ...

  10. Contingency plans for chromium utilization. Publication NMAB-335

    International Nuclear Information System (INIS)

    The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. This vulnerability results because chromium is essential for the fabrication of corrosion-resisting steels and high-temperature, oxidation-resisting alloys in applications that are vital to the nation's technological well-being; because no substitutes are known for these materials in those applications; and because the known, substantial deposits of chromite ore are only in a few geographical locations that could become inaccessible to the United States as a result of political actions. The effectiveness of programs such as stockpiling, conservation, and research and development for substitutes to reduce the impact of disruption of imports of chromite and ferrochromium are discussed. Alternatives for decreasing chromium consumption also are identified for chromium-containing materials in the areas of design, processing, and substitution

  11. Synthesis and characterization of novel chromium pillared clays

    International Nuclear Information System (INIS)

    New chromium pillared clays of basal spacing 2.45 nm were synthesized and characterized. The chromium oligomers used for intercalation were prepared by quick addition of base and acid to Cr(III) monomeric solutions followed by reflux. The synthesized clays exhibit increased BET surface area and higher micropore volume compared to clays with lower galleries, pillared either by smaller Cr(III) oligomers or by Cr(III) monomers. Important parameters affecting the d001 basal spacing were studied, e.g. the pH of the pillaring solution, the intercalation time, the chromium concentration and the counter-anion present in the chromium solutions. Scanning electron micrographs were acquired to demonstrate changes of the clay texture before and after pillaring. The thermal behavior of the synthesized clays was also examined

  12. Adsorption Properties of Chromium (VI by Chitosan Coated Montmorillonite

    Directory of Open Access Journals (Sweden)

    Dahe Fan

    2006-01-01

    Full Text Available The adsorption of chromium (VI by Chitosan Coated Montmorillonite (CCM from aqueous solution was studied. To evaluate the adsorption capacity, the effects of pH, initial concentration and temperature on the adsorption were investigated. The isothermal data was applied to Langmuir linear and the Freundlich linear isotherm equation and the thermodynamic parameters (ΔH, ΔG, ΔS were calculated according to the values of binding Langmuir constant, KL. Results indicated that the adsorption between CCM and chromium (VI was significantly physical, the negative ΔH constant at lower temperature confirmed that the more chromium (VI was adsorbed by chitosan coated montmorillonite at lower temperature. The kinetics of the sorption process of chromium (VI on chitosan coated montmorillonite were investigated using the pseudo-first order and pseudo-second order kinetics, results showed that the pseudo-second order equation model provided the best correlation with the experimental results.

  13. IRIS Toxicological Review of Hexavalent Chromium (Peer Review Plan)

    Science.gov (United States)

    EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessment of hexavalent chromium that will appear on the Integrated Risk Information System (IRIS) database.

  14. Fabrication of high rate chromium getter sources for fusion applications

    International Nuclear Information System (INIS)

    Design and fabrication techniques are described for the manufacture of large-capacity chromium getter sources, analogous to the commercially available titanium getter source known as Ti-Ball, manufactured by Varian Associates

  15. Detecting Grain-Boundary Chromium Depletion in Inconel 600

    Science.gov (United States)

    Airey, G. P.; Vaia, A. R.; Pessall, N.; Aspden, R. G.

    1981-11-01

    Techniques to evaluate grain-boundary chromium depletion in Inconel Alloy 600 were investigated. Procedures studied were a modified Huey test, reactivation polarization, magnetic permeability measurements, and eddy current measurements. Results from these tests were correlated with susceptibility to stress-assisted intergranular cracking in polythionic acid. Thermally treated Inconel Alloy 600 steam generator tubing was the principal source of material evaluated, but experimental heats of Ni-Cr-Fe alloys with 8-18 wt.% Cr were prepared to determine the critical chromium level below which stress-assisted intergranular cracking occurs; this critical chromium content was found to be between 9.8 and 11.7 wt.%. All four techniques were considered suitable to evaluate grain-boundary chromium depletion; the modified Huey test and reactivation polarization technique showed a greater sensitivity than the magnetic permeability and eddy current measurements.

  16. The diffusion of chromium in a duplex alloy steel

    International Nuclear Information System (INIS)

    Diffusion of chromium in a duplex stainless steel containing approximately 8% ferrite has been investigated in the temperature range 600 to 10000C using the standard serial sectioning technique. The resulting concentration profiles exhibited up to four distinct regions. The two main regions are attributed to volume diffusion in the austenite and ferrite phases, the other zones being due to short circuiting paths. Volume diffusion in the austenite phase is in good agreement with chromium diffusion in Type 316 steel. The chromium diffusion coefficient in the ferrite phase of approximate composition 25 wt % Cr, 5 wt % Ni is given by: Dsub(α) = (6.0(+11,-3)) x 10-6 exp - ((212+-5)/RT) m2s-1 the activation energy being expressed in kJ.mol-1. Little evidence was found for enhanced chromium diffusion along austenite/ferrite interface boundaries. (author)

  17. Chromium plating pollution source reduction by plasma source ion implantation

    International Nuclear Information System (INIS)

    There is growing concern over the environmental toxicity and workers' health issues due to the chemical baths and rinse water used in the hard chromium plating process. In this regard the significant hardening response of chromium to nitrogen ion implantation can be environmentally beneficial from the standpoint of decreasing the thickness and the frequency of application of chromium plating. In this paper the results of a study of nitrogen ion implantation of chrome plated test flats using the non-line-of-sight Plasma Source Ion Implantation (PSII) process, are discussed. Surface characterization was performed using Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), and Electron Spectroscopy for Chemical Analysis (ESCA). The surface properties were evaluated using a microhardness tester, a pin-on-disk wear tester, and a corrosion measurement system. Industrial field testing of nitrogen PSII treated chromium plated parts showed an improvement by a factor of two compared to the unimplanted case

  18. New Chromium Carbonyl Catalysts for [6+2] Cycloaddition Reactions

    OpenAIRE

    Kundig, Ernst Peter; Robvieux, Fabrice; Kondratenko, Mikhail

    2002-01-01

    The complexes, (benzene)chromiumdicarbonyl(methyl acrylate) and chromiumdicarbonylbis(cyclohexadiene), are precursors for the highly coordinatively unsaturated chromium dicarbonyl fragment 3, a catalyst for the cycloaddition of activated olefins to cycloheptatriene.

  19. Biosorption of Chromium (VI) from Aqueous Solutions onto Fungal Biomass

    OpenAIRE

    Ismael Acosta R.; Xöchitl Rodríguez; Conrado Gutiérrez; Ma. de Guadalupe Moctezuma

    2004-01-01

    The biosorption of chromium (VI) on eighteen different natural biosorbents: Natural sediment, chitosan, chitin, Aspergillus flavus I-V, Aspergillus fumigatus I-ll, Helmintosporium sp, Cladosporium sp, Mucor rouxii mutant, M. rouxii IM-80, Mucor sp-I and 2, Candida albicans and Cryptococcus neoformans was studied in this work. It was found that the biomass of C. neoformans, natural sediment, Helmintosporium sp and chitosan was more efficient to remove chromium (VI) (determined spectrophotometr...

  20. Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

    OpenAIRE

    Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

    2013-01-01

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel sau...

  1. Genetic Predisposition for Dermal Problems in Hexavalent Chromium Exposed Population

    OpenAIRE

    Priti Sharma; Vipin Bihari; Agarwal, Sudhir K.; Goel, Sudhir K.

    2012-01-01

    We studied the effect of genetic susceptibility on hexavalent chromium induced dermal adversities. The health status of population was examined from the areas of Kanpur (India) having the elevated hexavalent chromium levels in groundwater. Blood samples were collected for DNA isolation to conduct polymorphic determination of genes, namely: NQO1 (C609T), hOGG1 (C1245G), GSTT1, and GSTM1 (deletion). Symptomatic exposed subjects (n = 38) were compared with asymptomatic exposed subjects (n = 108)...

  2. Chromium (V) compounds as cathode material in electrochemical power sources

    Science.gov (United States)

    Delnick, F.M.; Guidotti, R.A.; McCarthy, D.K.

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca/sub 5/(CrO/sub 4/)/sub 3/Cl, Ca/sub 5/(CrO/sub 4/)OH, and Cr/sub 2/O/sub 5/. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  3. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    Energy Technology Data Exchange (ETDEWEB)

    PETERSEN SW

    2009-07-02

    {sm_bullet} Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage {sm_bullet} Secondary Objective: Reduce hexavalent chromium to <48 parts per billion (ppb) in aquifer (drinking water standard) - Large plumes with isolated areas of high chromium concentrations (> 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  4. DANGER OF HEXAVALENT CHROMIUM AND STRATEGY FOR THE REMEDITATION

    OpenAIRE

    Aniruddha Roy; Ayan Das; Nirmal Paul

    2013-01-01

    Some metals as micronutrients have a major role in the life and growth process of plants and animals. However, certain forms of some metals may also act as toxic material even in relatively small quantities. Chromium is such a metal, whose concentration above a certain limit may cause a serious problem to the health of living organisms. Chromium (Cr) may occur in several chemical forms in organic and inorganic systems. In biological systems only Cr (III) and Cr (VI) are signifi...

  5. Stereology of carbide phase in modified hypereutectic chromium cast iron

    Directory of Open Access Journals (Sweden)

    J. Suchoń

    2010-04-01

    Full Text Available In paper are presented results of studies of carbide phase stereology modified hypereutectic wear resistance chromium cast iron which contains carbon about 3,5% and chromium about 25%. Three substances were applied to the modification: boron carbide (B4C, ferroniobium (FeNb and mixture of ferroniobium and rare-earth (RE. The measurements of geometrical features of carbides were conducted on microsection taken from castings wich were cooled with various velocities.

  6. Stereology of carbide phase in modified hypereutectic chromium cast iron

    OpenAIRE

    J. Suchoń; A. Studnicki; M. Przybył

    2010-01-01

    In paper are presented results of studies of carbide phase stereology modified hypereutectic wear resistance chromium cast iron which contains carbon about 3,5% and chromium about 25%. Three substances were applied to the modification: boron carbide (B4C), ferroniobium (FeNb) and mixture of ferroniobium and rare-earth (RE). The measurements of geometrical features of carbides were conducted on microsection taken from castings wich were cooled with various velocities.

  7. Chromium reduction from slag on electromelting of stainless steel

    International Nuclear Information System (INIS)

    Specific features of chromium reduction from the slag on electromelting of stainless steel type Kh18N10T according to one- or two-slag procedure were studied. It was shown that one-slag melting technology allows double decrease of chromium losses in the form of incompletely reduced oxides. This occurs due to additional chemical reactions between metal and slag on their combined pouring into the ladle. 1 ref.; 3 figs

  8. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery Furnaces XII Appendix XII to Part 266... FACILITIES Pt. 266, App. XII Appendix XII to Part 266—Nickel or Chromium-Bearing Materials that may...

  9. Evaluating trivalent chromium toxicity on wild terrestrial and wetland plants.

    Science.gov (United States)

    Lukina, A O; Boutin, C; Rowland, O; Carpenter, D J

    2016-11-01

    Elevated chromium levels in soil from mining can impact the environment, including plants. Mining of chromium is concentrated in South Africa, several Asian countries, and potentially in Northern Ontario, Canada, raising concerns since chromium toxicity to wild plants is poorly understood. In the first experiment, concentration-response tests were conducted to evaluate effects of chromium on terrestrial and wetland plants. Following established guidelines using artificial soil, seeds of 32 species were exposed to chromium (Cr(3+)) at concentrations simulating contamination (0-1000 mg kg(-1)). This study found that low levels of chromium (250 mg kg(-1)) adversely affected the germination of 22% of species (33% of all families), while higher levels (500 and 1000 mg kg(-1)) affected 69% and 94% of species, respectively, from 89% of the families. Secondly, effects on seedbanks were studied using soil collected in Northern Ontario and exposed to Cr(3+) at equivalent concentrations (0-1000 mg kg(-1)). Effects were less severe in the seedbank study with significant differences only observed at 1000 mg kg(-1). Seeds exposed to Cr(3+) during stratification were greatly affected. Seed size was a contributing factor as was possibly the seed coat barrier. This study represents an initial step in understanding Cr(3+) toxicity on wild plants and could form the basis for future risk assessments. PMID:27543852

  10. Wear resistance of chromium cast iron – research and application

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2006-04-01

    Full Text Available Purpose: A short characteristic of wear resistance chromium cast iron has been presented as well as possibilities of this material researches realization in Foundry Department have been discussed.Design/methodology/approach: Main attention was given on research process of crystallization and analysis of chromium cast iron microstructure and its resistance on erosion wears. Separate part of paper was devoted to discuss the bimetallic castings with chromium cast iron layer as well as typical applications of chromium cast iron castings in minig, proccesing, metallurgical and power industry.Findings: The new method of crystallization process research with three testers (DTA-K3 was found in the work. The method makes possible to characterize sensitivity of chromium cast iron on cooling kinetic.Research limitations/implications: DTA-K3 method can be used for research of crystallization proccess of cast materials particularly for abrasion-resisting alloy.Practical implications: Wide scope researches of chromium cast iron in Foundry Department enable extending applications its material in many industries.Originality/value: Value of the paper is the presentation of researches possibilities which undertaken in Foundry Department within the range of wear resistant materials.

  11. Experimental skin deposition of chromium on the hands following handling of samples of leather and metal

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P.; Jellesen, Morten Stendahl;

    2016-01-01

    Background: Chromium is an important skin sensitizer. Exposure to it has been regulated in cement, and recently in leather. Studies on the deposition of chromium ions on the skin as a result of handling different chromium-containing materials are sparse, but could improve the risk assessment of...... contact sensitization and allergic contact dermatitis caused by chromium. Objectives: To determine whether the handling of chromium-containing samples of leather and metal results in the deposition of chromium onto the skin. Methods: Five healthy volunteers participated. For 30 min, they handled samples...... of leather and metal known to contain and release chromium. Skin deposition of chromium was assessed with the acid wipe sampling technique. Results: Acid wipe sampling of the participants' fingers showed chromium deposition on the skin in all participants who had been exposed to leather (range 0...

  12. Effect of recasting on the thickness of metal-ceramic interface of nickel-chromium and cobalt-chromium alloys

    OpenAIRE

    Mirković Nemanja; Draganjac Miroslav; Stamenković Dragoslav; Ristić Ljubiša

    2008-01-01

    Introduction/Aim. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the thickness of their metal-ceramic interface in making fixed partial dentures. Metal-ceramic interface determines their functional integrity and prevents damages on ceramics during mastication. Investigation of metal-ceramic samples is supposed to show if base metal alloys for metalceramics are successfully recycled without any risk of reduction of metal-ceramic interface...

  13. USE OF TWO DIGESTION METHODS IN THE EVALUATION OF CHROMIUM CONTENT IN CATTLE'S MEAT SUPPLEMENTED WITH CHROMIUM CHELATES

    OpenAIRE

    R. L. T. Andrade; P.S.A. Moreira; R. Arruda; F. J. Lourenço; C. Palhari, F. F. Faria, V. B. Arevalo; Faria, F. F.; V. B. Arevalo

    2015-01-01

    The present study aimed to analyze the chromium content in beef using two digestion methods. There were used samples from 24 18-month-old male cattle, and twelve of them were supplemented and twelve were not supplemented with chromium chelate. These samples were evaluated by atomic absorption spectroscopy, previously submitted to digestion method using nitric acid (65%) with hydrogen peroxide (35%) and to digestion method, using solution of nitric perchloric acid in the proportion 3:1. Immedi...

  14. Activation of bentonite to remove the chromium from waste water produced by panning industry, and studying the chromium recovery efficiency

    International Nuclear Information System (INIS)

    The fast development of tanning industry led to an increase in environmental problems resulting from discharging its wastes to the surrounding environment. Thus solving this problem became one of the most important aims that the researchers work on. The chromium content of the industrial water wastes of the tanning industry considered as the main pollutant for the environment. The Aleppo Bentonite is used in early research to remove the chromium from the industrial waste water.The current research aims to find a method to activate the Aleppo Bentonite in order to increase the effective removal of chromium from the industrial waste water which is produced by tanning industry, as well as to specify the optimal conditions for chromium recovery.This study used the Aleppo Bentonite, whose origin is Tal Ajar-Aleppo to study the activation aspects using Sulfuric Acid, Hydrochloric Acid and Nitric Acid, in addition to study the recovery aspects using the same acids and hydrogen peroxide and to specify the optimal conditions for chromium recovery through applying some experiments based on three main factors: concentration, settling time and temperature.It was observed from the applied experiments that it is possible to recover chromium from Bentonite efficiently up to (80% - 90%) by treating the Bentonite with hydrogen peroxide(33% concentration) at room temperature, or by treating it with hydrogen peroxide(8.25% concentration) at 75oC, while the settling time factor proved that full recovery of chromium is obtained during the first hour, and increasing the time factor does not affect the efficiency of chromium recovery. (author)

  15. Scientific Opinion on chromium(III) lactate tri-hydrate as a source of chromium added for nutritional purposes to foodstuff

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)

    2012-01-01

    The Panel on Food Additives and Nutrient Sources added to Food provides a scientific opinion on the safety and bioavailability of chromium(III) lactate tri-hydrate as a source of chromium(III) added for nutritional purposes to foodstuffs. The safety of chromium itself, in terms of the amounts that may be consumed, is outside the remit of this Panel. No new data have been provided as regards the safety and bioavailability of chromium from chromium(III) lactate tri-hydrate. The Panel c...

  16. Iron selenide films by aerosol assisted chemical vapor deposition from single source organometallic precursor in the presence of surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Raja Azadar [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Badshah, Amin, E-mail: aminbadshah@yahoo.com [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Younis, Adnan [School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia); Khan, Malik Dilshad [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Akhtar, Javeed [Department of Physics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, Islamabad (Pakistan)

    2014-09-30

    This article presents the synthesis and characterization (multinuclear nuclear magnetic resonance, Fourier transform infrared spectroscopy, carbon–hydrogen–nitrogen–sulfur analyzer, atomic absorption spectrometry and thermogravimetric analysis) of a single source organometallic precursor namely 1-acetyl-3-(4-ferrocenylphenyl)selenourea for the fabrication of iron selenide (FeSe) films on glass substrates using aerosol assisted chemical vapor deposition (AACVD). The changes in the morphologies of the films have been monitored by the use of two different surfactants i.e. triton X-100 and tetraoctylphosphonium bromide during AACVD. The role of surfactant has been evaluated by examining the interaction of the surfactants with the precursor by using UV–vis spectroscopy and cyclic voltammetry. The fabricated FeSe films have been characterized with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. - Highlights: • Ferrocene incorporated selenourea (FIS) has been synthesized and characterized. • FeSe thin films have been fabricated from FIS. • Mechanism of film growth was studied with cyclic voltammetry and UV–vis spectroscopy.

  17. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    International Nuclear Information System (INIS)

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 2250C without any signs of thermal performance degradation

  18. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors

    Science.gov (United States)

    Wang, Qisi; Park, J. T.; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J. W.; Ivanov, A.; Chi, Songxue; Matsuda, M.; Cao, Huibo; Birgeneau, R. J.; Efremov, D. V.; Zhao, Jun

    2016-05-01

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s -wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s± or d -wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in Tc in the S-doped iron selenide superconductors KxFe2 -y(Se1-zSz) 2 . We show that a rather sharp magnetic resonant mode well below the superconducting gap (2 Δ ) in the undoped sample (z =0 ) is replaced by a broad hump structure above 2 Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

  19. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    Science.gov (United States)

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. PMID:26615488

  20. Structural and Optical Studies of 100 MeV Ni+7 Irradiated Cadmium Selenide Thin Films

    Directory of Open Access Journals (Sweden)

    Rajesh Singh

    2015-10-01

    Full Text Available The effect of irradiation with Swift (100 MeV Ni+ 7 ions on the structural and optical properties of Cadmium Selenide (CdSe thin films have been investigated at different fluencies in the range of 1  1011-1  1013 ions/cm – 2. The CdSe films on glass substrates were prepared by thermal evaporation. The structural and optical changes with respect to increasing fluence were observed by the means of X-ray diffraction (XRD, UV-VIS and Raman spectroscopy. After irradiating the films with Ni+ 7 ions XRD show the increased in peak intensity and crystallite size with increasing fluence. The UV-VIS-IR spectroscopy revealed that there is decrease in band gap energy of the films after irradiation with increasing fluencies. Raman spectrum for as deposited and irradiated films show two peak, one at 209 cm – 1 and at 410 cm – 1 which is assigned to the longitudinal optical (LO phonon mode.

  1. Influence of growth and photocatalytic properties of copper selenide (CuSe) nanoparticles using reflux condensation method

    International Nuclear Information System (INIS)

    Influence of reaction conditions on the synthesis of copper selenide (CuSe) nanoparticles and their photo degradation activity is studied. Nearly monodispersed uniform size (23–44 nm) nanoparticles are synthesized by varying the reaction conditions using reflux condensation method. The obtained nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV–visible absorption spectroscopy. The X-ray diffraction analysis of the sample shows the formation of nanoparticles with hexagonal CuSe structure. The result indicates that on increasing the reaction time from 4 to 12 h, the particle size decreases from 44 to 23 nm, but an increase in the reaction temperature increases the particle size. The calculated band gap Eg is ranging from 2.34 to 3.05 eV which is blue shifted from the bulk CuSe (2.2 eV). The photocatalytic degradation efficiency of the CuSe nanoparticles on two organic dyes Methylene blue (MB) and Rhodamine-B (RhB) in aqueous solution under UV region is calculated as 76 and 87% respectively.

  2. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    Energy Technology Data Exchange (ETDEWEB)

    Strazza, N.P.

    1979-06-30

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 225/sup 0/C without any signs of thermal performance degradation. (TFD)

  3. Highly Efficient Copper-Indium-Selenide Quantum Dot Solar Cells: Suppression of Carrier Recombination by Controlled ZnS Overlayers.

    Science.gov (United States)

    Kim, Jae-Yup; Yang, Jiwoong; Yu, Jung Ho; Baek, Woonhyuk; Lee, Chul-Ho; Son, Hae Jung; Hyeon, Taeghwan; Ko, Min Jae

    2015-11-24

    Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date. PMID:26431392

  4. Production of no-carrier-added radiobromine. new nickel selenide target and optimized separation by dry distillation

    Energy Technology Data Exchange (ETDEWEB)

    Breunig, Katharina; Spahn, Ingo; Spellerberg, Stefan; Coenen, Heinz H. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5)

    2015-07-01

    Nickel(II) selenide (NiSe) was investigated as a new high-current target material for cyclotron production of radiobromine, as it contains a higher amount of selenium and has a lower melting point than the widely used Cu{sub 2}Se. Using a slanted target system, NiSe was successfully tested up to beam currents of 16 μA so far. With regard to the isolation of no-carrier-added (n.c.a.) radiobromide from the target material, an improved dry distillation device with high yields of 76%-86% was developed. The implementation of a special custom-made quartz funnel decreased the dead volume of the apparatus and a quartz capillary for trapping the radiobromine allowed to concentrate the radioactivity in a small volume of less than 100 μL of 0.1 M NaOH, ready for immediate subsequent radiosyntheses. Thus, the new apparatus improves the handling of the isolation procedure and the radioactive product. The radiochemical purity of the resulting solution of n.c.a. [*Br]bromide was verified by radio-IC where no other species were detected.

  5. Temperature anomaly of the coefficient of ultrasonic absorption by electrons of hybridized states of cobalt impurities in mercury selenide

    Science.gov (United States)

    Zhevstovskikh, I. V.; Okulov, V. I.; Gudkov, V. V.; Mayakin, V. Yu.; Sarychev, M. N.; Andriichuk, M. D.; Paranchich, L. D.

    2015-05-01

    The effects of the interaction of ultrasound with donor d electrons of cobalt impurity atoms at low concentrations in mercury selenide crystals have been investigated. The temperature dependences of the electronic contribution to the absorption coefficient at a frequency of 53 MHz in crystals with cobalt concentrations from 1018 to 1020 cm-3 and in the undoped crystal have been observed experimentally. It has been found that crystals with impurities are characterized by an anomalous nonmonotonic temperature dependence of the absorption coefficient of the slow transverse wave in a narrow temperature range near 10 K. A smooth monotonic temperature dependence has been observed for longitudinal and fast transverse waves. Based on the developed theoretical interpretation, it has been established that the anomaly in the temperature dependence of the absorption coefficient of a slow transverse wave is associated with the hybridization of impurity d states in the conduction band of the crystal. A comparison of the theoretical and experimental dependences has made it possible to determine the parameters characterizing the hybridized electronic states.

  6. Iron selenide films by aerosol assisted chemical vapor deposition from single source organometallic precursor in the presence of surfactants

    International Nuclear Information System (INIS)

    This article presents the synthesis and characterization (multinuclear nuclear magnetic resonance, Fourier transform infrared spectroscopy, carbon–hydrogen–nitrogen–sulfur analyzer, atomic absorption spectrometry and thermogravimetric analysis) of a single source organometallic precursor namely 1-acetyl-3-(4-ferrocenylphenyl)selenourea for the fabrication of iron selenide (FeSe) films on glass substrates using aerosol assisted chemical vapor deposition (AACVD). The changes in the morphologies of the films have been monitored by the use of two different surfactants i.e. triton X-100 and tetraoctylphosphonium bromide during AACVD. The role of surfactant has been evaluated by examining the interaction of the surfactants with the precursor by using UV–vis spectroscopy and cyclic voltammetry. The fabricated FeSe films have been characterized with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. - Highlights: • Ferrocene incorporated selenourea (FIS) has been synthesized and characterized. • FeSe thin films have been fabricated from FIS. • Mechanism of film growth was studied with cyclic voltammetry and UV–vis spectroscopy

  7. Loading of atorvastatin and linezolid in β-cyclodextrin-conjugated cadmium selenide/silica nanoparticles: A spectroscopic study.

    Science.gov (United States)

    Antony, Eva Janet; Shibu, Abhishek; Ramasamy, Sivaraj; Paulraj, Mosae Selvakumar; Enoch, Israel V M V

    2016-08-01

    The preparation of β-cyclodextrin-conjugated cadmium selenide-silica nanoparticles, the loading of two drugs viz., Atorvastatin and linezolid in the cyclodextrin cavity, and the fluorescence energy transfer between CdSe/SiO2 nanoparticles and the drugs encapsulated in the cyclodextrin cavity are reported in this paper. IR spectroscopy, X-ray diffractometry, transmission electron microscopy, and particle size analysis by light-scattering experiment were used as the tools of characterizing the size and the crystal system of the nanoparticles. The nanoparticles fall under hexagonal system. The silica-shell containing CdSe nanoparticles were functionalized by reaction with aminoethylamino-β-cyclodextrin. Fluorescence spectra of the nanoparticles in their free and drug-encapsulated forms were studied. The FÖrster distances between the encapsulated drugs and the CdSe nanoparticles are below 3nm. The change in the FÖrster resonance energy parameters under physiological conditions may aid in tracking the release of drugs from the cavity of the cyclodextrin. PMID:27157743

  8. Syntheses and characterization of two new selenides Ba5Al2Se8 and Ba5Ga2Se8

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Research highlights: → Two new compounds Ba5M2Se8 (M = Al, Ga) have been synthesized for the first time. → The crystal structures contain isolated MSe4 tetrahedra separated by Ba atoms. → The measured optical band gap is 2.51(2) eV for Ba5Ga2Se8. → The Ba 5d orbitals were found to have significant contribution to the energy bands around Fermi level. - Abstract: Two new barium selenides Ba5Al2Se8 and Ba5Ga2Se8 have been synthesized by solid-state reactions. The structures of Ba5Ga2Se8 and Ba5Al2Se8 were determined by single-crystal X-ray diffraction method and the Rietveld method, respectively. The two isostructural compounds crystallize in space group Cmca of the orthorhombic system with isolated MSe4 (M = Al, Ga) tetrahedra separated by Ba atoms. The optical band gap of 2.51(2) eV for Ba5Ga2Se8 was deduced from the diffuse reflectance spectrum. Band structure calculation indicates that Ba5Ga2Se8 is a direct-gap semiconductor. The valence band maximum is dominated by Se 4p orbitals, while the Ba 5d orbitals have the largest contribution to bottom of the conduction band.

  9. Production of no-carrier-added radiobromine. new nickel selenide target and optimized separation by dry distillation

    International Nuclear Information System (INIS)

    Nickel(II) selenide (NiSe) was investigated as a new high-current target material for cyclotron production of radiobromine, as it contains a higher amount of selenium and has a lower melting point than the widely used Cu2Se. Using a slanted target system, NiSe was successfully tested up to beam currents of 16 μA so far. With regard to the isolation of no-carrier-added (n.c.a.) radiobromide from the target material, an improved dry distillation device with high yields of 76%-86% was developed. The implementation of a special custom-made quartz funnel decreased the dead volume of the apparatus and a quartz capillary for trapping the radiobromine allowed to concentrate the radioactivity in a small volume of less than 100 μL of 0.1 M NaOH, ready for immediate subsequent radiosyntheses. Thus, the new apparatus improves the handling of the isolation procedure and the radioactive product. The radiochemical purity of the resulting solution of n.c.a. [*Br]bromide was verified by radio-IC where no other species were detected.

  10. An approach to global rovibrational analysis based on anharmonic ladder operators: Application to Hydrogen Selenide (H280Se)

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic diagram of a bent triatomic molecule, depicting the atom numbering, and molecular axis system. An algebraic approach to perform global rovibrational analysis is presented. Highlights: ► Novel approach for a global rovibrational analysis of polyatomic molecules spectra. ► One-dimensional vibron model limit combined with rotational degrees of freedom. ► Phase space Hamiltonian written in terms of anharmonic ladder operators. ► Algebraic calculations performed with a symmetry-adapted rovibrational basis. ► Description of the rovibrational spectrum of H2Se in the ground electronic state. - Abstract: An algebraic approach to perform global rovibrational analysis of molecular spectra is presented. The approach combines the one-dimensional limit of the vibron model with rotational degrees of freedom. The model is based on the expression of the phase space Hamiltonian in terms of anharmonic ladder operators and the use of a symmetry-adapted basis set given by the linear combination of products of local vibrational and rotational wavefunctions. As an example we model the rovibrational spectra of a bent triatomic molecule, providing a global analysis for vibrational bands up to polyad 12 and Jmax = 5 of Hydrogen Selenide (H2Se). Satisfactory fits of vibrational and rovibrational energies are obtained. A prediction of 2579 rovibrational energies up to J ⩽ 5 and polyad 12 for the 140 lowest vibrational bands is also obtained. A possible extension of the model to reach spectroscopic quality results in larger molecular systems is also given.

  11. Digital radiology using active matrix readout of amorphous selenium: radiation hardness of cadmium selenide thin film transistors.

    Science.gov (United States)

    Zhao, W; Waechter, D; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector using active matrix readout of amorphous selenium (a-Se) is being investigated for digital radiography and fluoroscopy. The active matrix consists of a two-dimensional array of thin film transistors (TFTs). Radiation penetrating through the a-Se layer will interact with the TFTs and it is important to ensure that radiation induced changes will not affect the operation of the x-ray imaging detector. The methodology of the present work is to investigate the effects of radiation on the characteristic curves of the TFTs using individual TFT samples made with cadmium selenide (CdSe) semiconductor. Four characteristic parameters, i.e., threshold voltage, subthreshold swing, field effect mobility, and leakage current, were examined. This choice of parameters was based on the well established radiation damage mechanisms for crystalline silicon metal-oxide-semiconductor field-effect transistors (MOSFETs), which have a similar principle of operation as CdSe TFTs. It was found that radiation had no measurable effect on the leakage current and the field effect mobility. However, radiation shifted the threshold voltage and increased the subthreshold swing. But even the estimated lifetime dose (50 Gy) of a diagnostic radiation detector will not affect the normal operation of an active matrix x-ray detector made with CdSe TFTs. The mechanisms of the effects of radiation will be discussed and compared with those for MOSFETs and hydrogenated amorphous silicon (a-Si:H) TFTs. PMID:9571621

  12. Pulsed voltage deposited lead selenide thin film as efficient counter electrode for quantum-dot-sensitized solar cells

    Science.gov (United States)

    Jin, Bin Bin; Wang, Ye Feng; Wang, Xue Qing; Zeng, Jing Hui

    2016-04-01

    Lead selenide (PbSe) thin films were deposited on fluorine doped tin oxide (FTO) glass by a facile one-step pulse voltage electrodeposition method, and used as counter electrode (CE) in CdS/CdSe quantum dot-sensitized solar cells (QDSSCs). A power conversion efficiency of 4.67% is received for the CdS/CdSe co-sensitized solar cells, which is much better than that of 2.39% received using Pt CEs. The enhanced performance is attributed to the extended absorption in the near infrared region, superior electrocatalytic activity and p-type conductivity with a reflection of the incident light at the back electrode in addition. The physical and chemical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), reflectance spectra, electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The present work provides a facile pathway to an efficient CE in the QDSSCs.

  13. Thin-film copper indium gallium selenide solar cell based on low-temperature all-printing process.

    Science.gov (United States)

    Singh, Manjeet; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-09-24

    In the solar cell field, development of simple, low-cost, and low-temperature fabrication processes has become an important trend for energy-saving and environmental issues. Copper indium gallium selenide (CIGS) solar cells have attracted much attention due to the high absorption coefficient, tunable band gap energy, and high efficiency. However, vacuum and high-temperature processing in fabrication of solar cells have limited the applications. There is a strong need to develop simple and scalable methods. In this work, a CIGS solar cell based on all printing steps and low-temperature annealing is developed. CIGS absorber thin film is deposited by using dodecylamine-stabilized CIGS nanoparticle ink followed by printing buffer layer. Silver nanowire (AgNW) ink and sol-gel-derived ZnO precursor solution are used to prepare a highly conductive window layer ZnO/[AgNW/ZnO] electrode with a printing method that achieves 16 Ω/sq sheet resistance and 94% transparency. A CIGS solar cell based on all printing processes exhibits efficiency of 1.6% with open circuit voltage of 0.48 V, short circuit current density of 9.7 mA/cm(2), and fill factor of 0.34 for 200 nm thick CIGS film, fabricated under ambient conditions and annealed at 250 °C. PMID:25180569

  14. Creep deformation of TD--nickel chromium

    International Nuclear Information System (INIS)

    The creep behavior of thoria dispersed nickel-chromium (TD-NiCr) was examined at 10930C. Major emphasis was placed on 1) the effects of the material and the test related variables (grain size, temperature, stress, strain and strain rate) on the deformation characteristics, and 2) the evaluation of single crystal TD-NiCr material produced by a directional recrystallization technique. Creep activation enthalpies were found to increase with increasing grain size reaching maximum values for the single crystal TD-NiCr. Stress exponent of the steady state creep rate was also significantly higher for the single crystal material as compared with that determined for the polycrystalline TD-NiCr. The elevated temperature deformation of TD-NiCr was analyzed in terms of two parallel-concurrent processes: 1) diffusion controlled grain boundary sliding and 2) dislocation motion. The characteristics of the dislocation motion deformation mode (as observed in the single crystal TD-NiCr) suggest that strong particle-dislocation interactions are present. The relative contributions of dislocation motion and grain boundary sliding in TD-NiCr were estimated. In creep, grain boundary sliding was found to predominate for the small, equiaxed grain structures, whereas the dislocation deformation mode became significant for only the large grain TD-NiCr and the single crystal material

  15. Low energy spin excitations in chromium metal

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R. [Los Alamos National Lab., NM (United States); Azuah, R.T. [Hahn-Meitner-Inst., Berlin (Germany); Stirling, W.G. [Univ. of Liverpool (United Kingdom). Dept. of Physics; Kulda, J. [Inst. Laue Langevin, Grenoble (France)

    1997-12-31

    Neutron scattering experiments with full polarization analysis have been performed with a single crystal of chromium to study the low-energy spin fluctuations in the transverse spin density wave (TSDW) state. A number of remarkable results have been found. Inelastic scattering observed close to the TSDW satellite positions at (1 {+-} {delta},0,0) does not behave as expected for magnon scattering. In particular, the scattering corresponds to almost equally strong magnetization fluctuations both parallel and perpendicular to the ordered moments of the TSDW phase. As the Neel temperature is approached from below, scattering at the commensurate wavevector (1,0,0) increases in intensity as a result of critical scattering at silent satellites (1,0, {+-} {delta}) being included within the spectrometer resolution function. This effect, first observed by Sternlieb et al, does not account for all of the inelastic scattering around the (1,0,0) position, however, Rather, there are further collective excitations, apparently emanating from the TSDW satellites, which correspond to magnetic fluctuations parallel to the ordered TSDW moments. These branches have a group velocity that is close to that of (1,0,0) longitudinal acoustic (LA) phonons, but assigning their origin to magneto-elastic scattering raises other unanswered questions.

  16. A Rare Terminal Dinitrogen Complex of Chromium

    Energy Technology Data Exchange (ETDEWEB)

    Mock, Michael T.; Chen, Shentan; Rousseau, Roger J.; O' Hagan, Molly J.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.; Bullock, R. Morris

    2011-10-12

    The reduction of dinitrogen to ammonia from N2 and H2 is currently carried out by the Haber-Bosch process, an energy intensive process that requires high pressures and high temperatures and accounts for the production of millions of tons of ammonia per year. The development of a catalytic, energy-efficient process for N2 reduction is of great interest and remains a formidable challenge. In this communication, we are reporting the preparation, characterization and computational electronic structure analysis of a rare 'Chatt-type' ((P-P)2M(N2)2, P-P = diphosphine ligand) complex of chromium, cis-[Cr(N2)2(PPh2NBn2)2] and its reactivity with CO. This complex is supported by the diphosphine ligand PPh2NBn2, containing non-coordinating pendant amine bases, to serve as proton relays. Future studies for this complex are aimed at answering fundamental questions regarding the role of proton relays in the second coordination sphere in their ability to facilitate proton movement from an external acid to metal-bound dinitrogen ligands in the challenging multi-proton/electron reduction of N2 to ammonia.

  17. A Rare Terminal Dinitrogen Complex of Chromium

    International Nuclear Information System (INIS)

    The reduction of dinitrogen to ammonia from N2 and H2 is currently carried out by the Haber-Bosch process, an energy intensive process that requires high pressures and high temperatures and accounts for the production of millions of tons of ammonia per year. The development of a catalytic, energy-efficient process for N2 reduction is of great interest and remains a formidable challenge. In this communication, we are reporting the preparation, characterization and computational electronic structure analysis of a rare 'Chatt-type' ((P-P)2M(N2)2, P-P = diphosphine ligand) complex of chromium, cis-(Cr(N2)2(PPh2NBn2)2) and its reactivity with CO. This complex is supported by the diphosphine ligand PPh2NBn2, containing non-coordinating pendant amine bases, to serve as proton relays. Future studies for this complex are aimed at answering fundamental questions regarding the role of proton relays in the second coordination sphere in their ability to facilitate proton movement from an external acid to metal-bound dinitrogen ligands in the challenging multi-proton/electron reduction of N2 to ammonia.

  18. Hexavalent Chromium Reduction and Its Distribution in the Cell and Medium by Chromium Resistant Fusarium solani

    Directory of Open Access Journals (Sweden)

    Mousumi Sen

    2013-01-01

    Full Text Available In the present work, batch biosorption of Cr(VI was studied using the fungal strain isolated from soil. The fungal strain was characterized as Fusarium solani. The total Cr distribution in the biomass (fungus and in the media obtained from the experiment conducted at 500 mg l -1 initial Cr(VI concentration and pH 5.0. The results indicated both intracellular and extracellular accumulation and enzymatic reduction of Cr(VI and this was supported by the Transmission Electron Microscopic (TEM observation at the same Cr(VI concentration and pH value. Chromium elution from Fusarium solani containing Cr was then tried out using a number of chromium eluting reagents and a maximum Cr could be eluted using 0.5N sodium hydroxide solution without destructing the biomass structure. The total Cr was recovered by pH adjustment from both biomass and media was found to be 44% of the initial Cr(VI concentration (500 mg l-1.

  19. Electron transfer. 75. Reduction of carboxylato-bound chromium(V) with vanadium(IV). Intervention of chromium(IV)

    International Nuclear Information System (INIS)

    The chelated (carboxylato)chromium(V) anion bis(2-hydroxy-2-ethylbutyrato)oxochromate(V) (I), [(Lig)2Cr(O)]-, reacts with oxovanadium(IV) to form a strongly absorbing species (lambda/sub max/ = 515 nm; epsilon = 1.7 x 103 M-1) in the presence of 2-hydroxy-2-ethylbutyric acid buffers (pH 2-4). EPR data support 1:1 stoichiometry with VO2+ in deficiency, indicating the formation of a chromium(IV) species by reduction. With excess VO2+ a chromium(III) product was obtained. Spectral and ion-exchange properties of this product correspond to those observed for the titanium(III) and iron(II) reductions of chromium(V) and are consistent with the formulation of the product as a bis(hydroxycarboxylate) chelate of (H2O)2Cr/sup III/. With excess vanadium(IV), the reaction exhibits triphasic kinetics. The remaining step of the reaction is the reduction of the chromium(IV) intermediate with VO2+. Rates for all steps increase with decreasing [H+] and level off at low [H+]. The limiting rate constants for the formation of the chromium(IV) intermediate by the (Lig)3Cr(O)2- and (Lig)2Cr(O)- pathways are 2.8 x 103 and 2.2 x 102 M-1s-1. The bimolecular limiting rate constant for the reduction of chromium(IV) is computed to be 7.7 x 102 M-1 s-1. 33 references, 7 tables

  20. Obtenção de filmes espessos de seleneto de cobre sobre carbono vítreo, ouro, titânio e cobre Obtaining copper selenide thick films on vitreous carbon, gold, titanium and copper

    Directory of Open Access Journals (Sweden)

    Adriano César Rabelo

    2007-04-01

    Full Text Available Copper selenide (berzelianite films were prepared on the title substrates using the chemical bath deposition technique (CBD. Film composition was determined by energy dispersion of x-rays. The kinetics of film growth is parabolic and film adherence limits the film thickness. On titanium, copper selenide forms islands that do not completely cover the surface, unless the substrate is prepared with a tin oxide layer; film composition also depends on the titanium oxide layer. On vitreous carbon, CBD and mechanical immobilization techniques lead to films with similar resistances for the electron transfer across the film/substrate interface. On gold, composition studies revealed that film composition is always the same if the pH is in the range from 8 to 12, in contrast to films prepared by an ion-ion combination route. On copper, a new procedure for obtaining copper selenide films as thick as 5 µm has been developed.

  1. Chromium propionate enhances adipogenic differentiation of bovine intramuscular adipocytes

    Directory of Open Access Journals (Sweden)

    Rebecca eTokach

    2015-09-01

    Full Text Available In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate on mRNA and protein abundance of different enzymes and receptors. Intramuscular and subcutaneous preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4 and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were treated with differentiation media plus either sodium propionate or different concentrations of chromium propionate (CrPro for 96, 120, and 144 h before harvest. This study indicated adipogenesis of the bovine intramuscular adipocytes were more sensitive to the treatment of chromium propionate as compared to subcutaneous adipocytes. Enhancement of adenosine monophosphate-activated protein kinase and GLUT4 mRNA by CrPro treatment may enhance glucose uptake in intramuscular adipocytes. Chromium propionate decreased GLUT4 protein levels in muscle cell cultures suggesting those cells have increased efficiency of glucose uptake due to exposure to increased levels of CrPro. In contrast, each of the two adipogenic lines had opposing responses to the CrPro. It appeared that CrPro had the most stimulative effect of GLUT4 response in the intramuscular adipocytes as compared to subcutaneous adipocytes. These findings indicated opportunities to potentially augment marbling in beef cattle fed chromium propionate during the finishing phase.

  2. Anthropogenic chromium emissions in china from 1990 to 2009.

    Science.gov (United States)

    Cheng, Hongguang; Zhou, Tan; Li, Qian; Lu, Lu; Lin, Chunye

    2014-01-01

    An inventory of chromium emission into the atmosphere and water from anthropogenic activities in China was compiled for 1990 through to 2009. We estimate that the total emission of chromium to the atmosphere is about 1.92×10⁵ t. Coal and oil combustion were the two leading sources of chromium emission to the atmosphere in China, while the contribution of them showed opposite annual growth trend. In total, nearly 1.34×10⁴ t of chromium was discharged to water, mainly from six industrial categories in 20 years. Among them, the metal fabrication industry and the leather tanning sector were the dominant sources of chromium emissions, accounting for approximately 68.0% and 20.0% of the total emissions and representing increases of 15.6% and 10.3% annually, respectively. The spatial trends of Cr emissions show significant variation based on emissions from 2005 to 2009. The emission to the atmosphere was heaviest in Hebei, Shandong, Guangdong, Zhejiang and Shanxi, whose annual emissions reached more than 1000t for the high level of coal and oil consumption. In terms of emission to water, the largest contributors were Guangdong, Jiangsu, Shandong and Zhejiang, where most of the leather production and metal manufacturing occur and these four regions accounted for nearly 47.4% of the total emission to water. PMID:24505309

  3. Anthropogenic chromium emissions in china from 1990 to 2009.

    Directory of Open Access Journals (Sweden)

    Hongguang Cheng

    Full Text Available An inventory of chromium emission into the atmosphere and water from anthropogenic activities in China was compiled for 1990 through to 2009. We estimate that the total emission of chromium to the atmosphere is about 1.92×10⁵ t. Coal and oil combustion were the two leading sources of chromium emission to the atmosphere in China, while the contribution of them showed opposite annual growth trend. In total, nearly 1.34×10⁴ t of chromium was discharged to water, mainly from six industrial categories in 20 years. Among them, the metal fabrication industry and the leather tanning sector were the dominant sources of chromium emissions, accounting for approximately 68.0% and 20.0% of the total emissions and representing increases of 15.6% and 10.3% annually, respectively. The spatial trends of Cr emissions show significant variation based on emissions from 2005 to 2009. The emission to the atmosphere was heaviest in Hebei, Shandong, Guangdong, Zhejiang and Shanxi, whose annual emissions reached more than 1000t for the high level of coal and oil consumption. In terms of emission to water, the largest contributors were Guangdong, Jiangsu, Shandong and Zhejiang, where most of the leather production and metal manufacturing occur and these four regions accounted for nearly 47.4% of the total emission to water.

  4. Enhancement of chromium uptake in tanning using oxazolidine.

    Science.gov (United States)

    Sundarapandiyan, S; Brutto, Patrick E; Siddhartha, G; Ramesh, R; Ramanaiah, B; Saravanan, P; Mandal, A B

    2011-06-15

    Monocyclic and bicyclic oxazolidines were offered at three different junctures of chrome tanning process viz. prior to BCS offer, along with BCS and after basification. It was found that oxazolidine when offered after basification brought about better chromium uptake and reduction of chromium load in the wastewater. Offer of oxazolidine was also varied. Increase in offer of oxazolidine from 0.25% to 1% was found to enhance the chromium uptake and decrease the chromium load in wastewater. But the increase in uptake was not proportionate to the increase in oxazolidine offer more than 0.75%. Offer of 1% Zoldine ZA 78 (monocyclic oxazolidine) and Zoldine ZE (bicyclic oxazolidine) after basification brought about 63.4% and 73.1% enhancement in chrome content in leather compared to control where oxazolidine was not offered. The tone of the wetblue was found to be altered moderately. However this did not call for any process adjustments in wet-finishing. The oxazolidine treated leathers were found to be immensely fuller and tighter. It was found experimentally that offer of 1% of oxazolidine facilitated reduction in the offer of syntans administered for filling and grain tightening by around 46%. Oxazolidine could bring about significant reduction in cost of chemicals apart from resulting environmental benefits due to enhancement of chromium uptake during tanning. PMID:21536383

  5. Low-chromium reduced-activation ferritic steels for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Kenik, E.A. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Development of reduced-activation ferritic steels has concentrated on high-chromium (8-10 wt% Cr) steels. However, there are advantages for a low-chromium steel, and initial ORNL studies on reduced-activation steels were on compositions with 2.25 to 12% Cr. Those studies showed an Fe-2.25Cr-2W-0.25V-0.1C (2 1/4Cr-2WV) steel to have the highest strenglth of the steels studied. Although this steel had the best strength, Charpy impact properties were inferior to those of an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) and an Fe-2.25Cr-2W-0.1C (2 1/4Cr-2W) steel. Therefore, further development of the low-chromium Cr-W steels was required. These results indicate that it is possible to develop low-chromium reduced-activation ferritic steels that have tensile and impact properties as good or better than those of high-chromium (7-9% Cr) steels. Further improvement of properties should be possible by optimizing the composition.

  6. FORMATION AND DESTRUCTION OF HEXAVALENT CHROMIUM IN A LABORATORY SWIRL FLAME INCINERATOR

    Science.gov (United States)

    The partitioning of chromium (Cr) in combustion systems was investigated theoretically and experimentally. Theoretical predictions were based on chemical equilibrium and suggested that hexavalent chromium [Cr(VI)] was favored by the presence of chlorine (Cl) and diminished by the...

  7. Chromium solubility in anhydrous Phase B

    Science.gov (United States)

    Bindi, Luca; Sirotkina, Ekaterina A.; Bobrov, Andrey V.; Nestola, Fabrizio; Irifune, Tetsuo

    2016-02-01

    The crystal structure and chemical composition of a crystal of (Mg14- x Cr x )(Si5- x Cr x )O24 ( x ≈ 0.30) anhydrous Phase B (Anh-B) synthesized in the model system MgCr2O4-Mg2SiO4 at 12 GPa and 1600 °C have been investigated. The compound was found to be orthorhombic, space group Pmcb, with lattice parameters a = 5.900(1), b = 14.218(2), c = 10.029(2) Å, V = 841.3(2) Å3 and Z = 2. The structure was refined to R 1 = 0.065 using 1492 independent reflections. Chromium was found to substitute for both Mg at the M3 site (with a mean bond distance of 2.145 Å) and Si at the octahedral Si1 site (mean bond distance: 1.856 Å), according to the reaction Mg2+ + Si4+ = 2Cr3+. Such substitutions cause a reduction in the volume of the M3 site and an increase in the volume of the Si-dominant octahedron with respect to the values typically observed for pure Anh-B and Fe2+-bearing Anh-B. Taking into account that Cr3+ is not expected to be Jahn-Teller active, it appears that both the Cr3+-for-Mg and Cr3+-for-Si substitutions in the Anh-B structure decrease the distortion of the octahedra. Electron microprobe analysis gave the Mg13.66(8)Si4.70(6)Cr0.62(4)O24 stoichiometry for the studied phase. The successful synthesis of this phase provides new information for the possible mineral assemblages occurring in the Earth's deep upper mantle and shed new light on the so-called X discontinuity that has been observed at 275-345 km depth in several subcontinental and subduction zone environments.

  8. Scientific Opinion on chromium(III lactate tri-hydrate as a source of chromium added for nutritional purposes to foodstuff

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS

    2012-10-01

    Full Text Available

    The Panel on Food Additives and Nutrient Sources added to Food provides a scientific opinion on the safety and bioavailability of chromium(III lactate tri-hydrate as a source of chromium(III added for nutritional purposes to foodstuffs. The safety of chromium itself, in terms of the amounts that may be consumed, is outside the remit of this Panel. No new data have been provided as regards the safety and bioavailability of chromium from chromium(III lactate tri-hydrate. The Panel concurs with its earlier views stating that no evidence was provided supporting the bioavailability of chromium from chromium(III lactate tri-hydrate. Chromium(III lactate tri-hydrate is claimed to be freely soluble in water, however, chromium(III lactate tri-hydrate exists as a weak complex that may influence the bioavailability of chromium(III in the gastrointestinal tract. The Panel re-iterates that because of the complex chemistry of chromium(III lactate tri-hydrate in aqueous solutions and its limited solubility at pH >5, the bioavailability of chromium(III from chromium(III lactate tri-hydrate is low. Based on a conservative exposure estimate, the Panel calculated the combined intake of chromium(III from supplements and from foods fortified with chromium(III lactate tri-hydrate, for both adults and children, to be approximately 240 μg chromium(III/day, which is below the value of 250 µg/day established by the WHO for supplemental intake of chromium that should not be exceeded. The Panel noted that the use of chromium(III lactate tri-hydrate in the form of a premix with lactose, added to foods, would result in an exposure at the mean for adults of approximately 7-37 mg lactose/day (0.12-0.62 μg lactose/kg bw/day and to 36-192 μg lactate/day (0.60-3.20 μg/kg bw/day. Given that subjects with lactose maldigestion will tolerate up to 12 g of lactose with no or minor symptoms, these levels are not of safety concern.

  9. Biosorption of hexavalent chromium in a tannery industry wastewater using fungi species

    OpenAIRE

    Sivakumar, D.

    2016-01-01

    The isolated fungi species of different kinds from chromium contaminated soil sites located in Nagalkeni, Chennai were used for reducing chromium(VI) in a tannery industry wastewater of Nagalkeni, Chennai.  The experiments were conducted to know biosorption potential of isolated fungi species for removing chromium(VI) in a tannery industry wastewater against the different pH, fungi biomass and chromium(VI) concentration (dilution ratio).  The results of this study indicated that the order of ...

  10. Investigation of hexavalent chromium removal from Synthetic wastewater by using Peaganum

    OpenAIRE

    Ali Akbar Taghizadeh; Maryam khodadadi; Taher Shahriary; Hadighe Dorri; mahla zaferanieh; rasoul khosravi

    2012-01-01

    Background and Aim: Discharge of industrial wastewater containing hexavalent chromium into the environment can have harmful effects to the types of organisms. So, chromium should remove before discharging to the environment with an effective method. The purpose of this study of is hexavalent chromium removed with Peganum harmala granular seeds(PGS).   Materials and Methods: In this experimental study, The removal of hexavalent chromium with using PGS, with changes in time, pH, adsorbent dose,...

  11. Chromium Exposure and Hygienic Behaviors in Printing Workers in Southern Thailand

    OpenAIRE

    Somsiri Decharat

    2015-01-01

    Objectives. The main objective of this study was to assess the chromium exposure levels in printing workers. The study evaluated the airborne, serum, and urinary chromium levels and determines any correlation between level of chromium in specimen and airborne chromium levels. Material and Methods. A cross-sectional study was conducted with 75 exposed and 75 matched nonexposed subjects. Air breathing zone was measured by furnace atomic absorption spectrophotometer. Serum and urine samples were...

  12. Structure and morphology studies of chromium film at elevated temperature in hypersonic environment

    OpenAIRE

    Hegde, GM; Kulkarni, V; Nagaboopathy, M; Reddy, KPJ

    2012-01-01

    This paper presents the after shock heated structural and morphological studies of chromium film coated on hypersonic test model as a passive drag reduction element. The structural changes and the composition of phases of chromium due to shock heating (2850 K) are characterized using X-ray diffraction studies. Surface morphology changes of chromium coating have been studied using scanning electron microscopy (SEM) before and after shock heating. Significant amount of chromium ablation and sub...

  13. Cutaneous absorption of trivalent chromium: tissue levels and treatment by exchange transfusion

    OpenAIRE

    Kelly, W F; Ackrill, P; Day, J P; O'Hara, Maureen; Tye, C T; Burton, I.; Orton, C.; Harris, M.

    1982-01-01

    ABSTRACT A man was accidentally immersed in hot acidic trivalent chromium sulphate solution but none was swallowed. The clinical course was dominated by burns, intravascular haemolysis, and acute renal failure. Blood concentrations of chromium were measured during treatment and tissue concentrations were measured at death. Exchange transfusion reduced blood chromium concentrations by two-thirds. The total quantities of chromium absorbed and removed by various routes were calculated. In-vitro ...

  14. The risk to groundwater from wastewater irrigation using high chromium tannery effluent

    OpenAIRE

    Stuart, M E; Milne, C. J.

    2001-01-01

    Wastewater from Leon containing high concentrations of chromium from the tanning industry is used to irrigate agricultural land overlying an aquifer used for to supply potable water. Chromium from irrigation water is accumulating in agricultural soils, and in the lagoon and canal sediments, but groundwater appears to be unaffected and chromium concentrations remain low. A limited area of very high chromium concnetrations in groundwater was confirmed to be derived from a factory supplying the ...

  15. Exploring the electronic structure and optical properties of the quaternary selenide compound, Ba4Ga4SnSe12: For photovoltaic applications

    International Nuclear Information System (INIS)

    Due to huge demand on discovering new materials for energy, we used first-principle calculations to explore the electronic structure and optical properties of a recent quaternary selenide, namely Ba4Ga4SnSe12. The electronic structure and the optical properties of Ba4Ga4SnSe12 were calculated through a reliable approach of Engle Vosko-GGA (EV-GGA). We found that Ba4Ga4SnSe12 has a direct band gap of 2.14 eV positioned at Γ. Acquiring the fundamental characteristics of Ba4Ga4SnSe12, we studied the linear optical properties like dielectric function in the energy range of 0–14 eV. From the dielectric function we noticed a weak directional anisotropy for the two components. The absorption spectrum indicates the possibility of greater multiple direct and indirect inter-band transitions in the visible regions and shows similar behavior with experimental spectrum. Ba4Ga4SnSe12 can be used as shielding material from UV radiations. Present study predicts that the Ba4Ga4SnSe12 is promising for photovoltaic applications due to their high absorption of solar radiations and photoconductivity in the visible range. - Graphical abstract: Interesting quaternary selenide compound, Ba4Ga4SnSe12, for photovoltaic applications. - Highlights: • Ba4Ga4SnSe12 is a quaternary selenide designed for PV and thermoelectric. • Ba4Ga4SnSe12 has a direct band gap of 2.14 eV. • Ba4Ga4SnSe12, has a maximum reflectivity in the visible and UV regions

  16. Liver Toxicity Resulted From Ingestion of Chromium Picolinate

    Directory of Open Access Journals (Sweden)

    Baltacı D et al.

    2010-03-01

    Full Text Available Herein, liver toxicity resulted from chronic ingestion of chromium picolinate, recommended daily allowance of over-the-counter (OTC have been presented. A woman of 32 years-old presented with pruritis since three days. On physical examination, she had no skin rashes, discoloration and urticarial lesions. With detailed inquiry of the patient, it has been determined that she had been using over-the-counter medicine containing chromium picolinate to enhance weight loss and increase lean body mass. On blood test examination follows: ALT: 484 U/I, AST: 182, Total/direct Bilirubin: 0,43/0,88 mg/dl. Complete Blood Count (CBC was normal. Chromium supplements may cause serious liver function impairment although when ingested within normal doses. Medication histories should include attention to the use of OTC nutritional supplements.

  17. Influence of chromium, oxygen, carbon and nitrogen on iron viscosity

    International Nuclear Information System (INIS)

    Kinetic viscosity of 70 beforehand melted iron samples with additions of chromium (up to 2%) and carbon (up to 1%) has been investigated. Different conditions of melting brought about differences in oxygen and nitrogen contents. Viscosity of most samples has been determined in the 1550-1650 deg C temperature range. It is stated that small additions to pure iron of each of the investigated elements (O, Cr, C, N) decrease its viscosity. Combined effect of these additions on viscosity is inadditive. Simultaneous introduction of oxygen and carbon may result in increase of melt viscosity. The same fact is observed at combined introduction of chromium and nitrogen. Simultaneous introduction of other impurities-chromium with oxygen or carbon, nitrogen with oxygen causes amplification of their individual effect. Reasons for the observed regularities result from changes in energies of interparticle interactions in the melt and therefore rebuilding of structure of its short-range order

  18. A study of the process of desorption of hexavalent chromium

    Directory of Open Access Journals (Sweden)

    W.B. Amorim

    2003-09-01

    Full Text Available In this work the process of desorption of hexavalent chromium, a toxic metal ion, from the marine algae Sargassum sp, following biosorption experiments 2³ factorial design was studied. A technique was applied to three eluents: HCl, H2SO4 and EDTA. Three factors of importance were evaluated: concentration of eluent, the ratio between mass of biosorbent and volume of eluent (S/L and process time. A statistical analysis of the experimental results showed that the three variables evaluated are significant for all three eluents. The models for chromium desorption were validated, as the results agreed well with the observed values. Through use of the response surface methodology, a factorial design based optimization technique; it was possible to identify the most suitable eluent and the interval of values for the process variables that resulted in the most significant desorption of chromium, which is relevant information for work aiming at process optimization.

  19. Structural and magnetic properties of chromium doped zinc ferrite

    International Nuclear Information System (INIS)

    Zinc chromium ferrites with chemical formula ZnCrxFe2−xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  20. Chromium Resistant Bacteria: Impact on Plant Growth in Soil Microcosm

    Directory of Open Access Journals (Sweden)

    Sayel Hanane

    2014-07-01

    Full Text Available Three chromium resistant bacterial strains, Pseudomonas fluorescens PF28, Enterobacter amnigenus EA31 and Enterococcus gallinarum S34 isolated from tannery waste contaminated soil were used in this study. All strains could resist a high concentration of K2Cr2O7 that is up to 300 mg/L. The effect of these strains on clover plants (Trifolium campestre in the presence of two chromium salts CrCl3 and K2Cr2O7 was studied in soil microcosm. Application of chromium salts adversely affected seed germination, root and shoot length. Bacterial inoculation improved the growth parameters under chromate stress when compared with non inoculated respective controls. There was observed more than 50% reduction of Cr(VI in inoculated soil microcosms, as compared to the uninoculated soil under the same conditions. The results obtained in this study are significant for the bioremediation of chromate pollution.

  1. Studies of removal of chromium by model constructed wetland

    Directory of Open Access Journals (Sweden)

    C. Mant

    2005-09-01

    Full Text Available Chromium is a pollutant present in tannery wastewater, its removal is necessary for protection of the environment. Penisetum purpureum, Brancharia decumbens and Phragmites australis were grown hydroponically in experimental gravel beds to determine their potential for the phytoremediation of solutions containing 10 and 20 mg Cr dm-3. These concentrations, similar to tannery wastewater after initial physico-chemical treatment were used with the aim of developing an economic secondary treatment to protect the environment. All the systems achieved removal efficiencies of 97 - 99.6% within 24 hours. P. purpureum and B. decumbens removed 78.1% and 68.5% respectively within the first hour. Both P. purpureum and B. decumbens were tolerant of the concentrations of chromium applied, but P. purpureum showed the greatest potential because its faster growth and larger biomass achieved a much greater chromium removal over the whole length of time of the experiment.

  2. On the rational alloying of structural chromium-nickel steels

    International Nuclear Information System (INIS)

    A study was made on the influence of chromium nickel, phosphorus on the critical brittleness temperature of Cr-Ni-Mo-V structural steels. It is shown that the critical brittleness temperature of these steels increases at chromium content more over than 2% and nickel content more than 2% in the result of carbide transformations during tempering. Increase of nickel content in Cr-Ni-Mo-V-steels strengthens the tendency to embrittlement during slow cooling, from tempering temperature owing to development of process of phosphorus grain-boundary segregation. Two mentioned mechanisms of embrittlement determine principles of rational steel alloying. The extreme dependence of the critical brittleness temperature on chromium and nickel content, which enables to choose the optimum composition of Cr-Ni-Mo-V-steels, was established

  3. Thin film metallic glass as a diffusion barrier for copper indium gallium selenide solar cell on stainless steel substrate: A feasibility study

    Science.gov (United States)

    Diyatmika, Wahyu; Xue, Lingjun; Lin, Tai-Nan; Chang, Chia-wen; Chu, Jinn P.

    2016-08-01

    The feasibility of using Zr53.5Cu29.1Al6.5Ni10.9 thin-film metallic glass (TFMG) as a diffusion barrier for copper indium gallium selenide (CIGS) solar cells on stainless steel (SS) is investigated. The detrimental Fe diffusion from SS into CIGS is found to be effectively hindered by the introduction of a 70-nm-thick TFMG barrier; the cell performance is thus improved. Compared with the 2.73% of CIGS on bare SS, a higher efficiency of 5.25% is obtained for the cell with the Zr52Cu32Al9Ni7 TFMG barrier.

  4. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    Science.gov (United States)

    Sandoval-Paz, M. G.; Rodríguez, C. A.; Porcile-Saavedra, P. F.; Trejo-Cruz, C.

    2016-07-01

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films.

  5. The stability domain of the selenide kesterite photovoltaic materials and NMR investigation of the Cu/Zn disorder in Cu2ZnSnSe4 (CZTSe).

    Science.gov (United States)

    Choubrac, Léo; Lafond, Alain; Paris, Michaël; Guillot-Deudon, Catherine; Jobic, Stéphane

    2015-06-21

    Bulk compounds, prepared via the ceramic route, related to Cu2ZnSnSe4 (CZTSe), a material considered for use in photovoltaic devices, were investigated using NMR spectroscopy, electron-probe microanalyses and X-ray diffraction. These materials adopt the kesterite structure regardless of the Cu and Zn contents. It is also shown that the stability domain of the copper-poor quaternary phases is wider for selenide derivatives than for sulphides. Finally, the Cu/Zn disorder level in CZTSe is found to be higher when the samples are quenched, which is reminiscent of the behaviour of the parent sulphide compounds CZTS. PMID:25990030

  6. Chromium accumulation by the hyperaccumulator plant Leersia hexandra Swartz.

    Science.gov (United States)

    Zhang, Xue-Hong; Liu, Jie; Huang, Hai-Tao; Chen, Jun; Zhu, Yi-Nian; Wang, Dun-Qiu

    2007-04-01

    Leersia hexandra Swartz (Gramineae), which occurs in Southern China, has been found to be a new chromium hyperaccumulator by means of field survey and pot-culture experiment. The field survey showed that this species had an extraordinary accumulation capacity for chromium. The maximum Cr concentration in the dry leaf matter was 2978 mg kg(-1) on the side of a pond near an electroplating factory. The average concentration of chromium in the leaves was 18.86 times as that in the pond sediment, and 297.41 times as that in the pond water. Under conditions of the nutrient solution culture, it was found that L. hexandra had a high tolerance and accumulation capacity to Cr(III) and Cr(VI). Under 60 mg l(-1) Cr(III) and 10 mg l(-1) Cr(VI) treatment, there was no significant decrease of biomass in the leaves of L. hexandra (p>0.05). The highest bioaccumulation coefficients of the leaves for Cr(III) and Cr(VI) were 486.8 and 72.1, respectively. However, L. hexandra had a higher accumulation capacity for Cr(III) than for Cr(VI). At the Cr(III) concentration of 10 mg l(-1) in the culture solution, the concentration of chromium in leaves was 4868 mg kg(-1), while at the same Cr(VI) concentration, the concentration of chromium in leaves was only 597 mg kg(-1). These results confirmed that L. hexandra is a chromium hyperaccumulator which grows rapidly with a great tolerance to Cr and broad ecological amplitude. This species could provide a new plant resource that explores the mechanism of Cr hyperaccumulation, and has potential for usage in the phytoremediation of Cr-contaminated soil and water. PMID:17207838

  7. Heat resistance of carbon steel with chromium-based gas-thermal sprayed coatings

    International Nuclear Information System (INIS)

    Heat resistance of steel with chromium-base plasma sprayed coating is studied in comparison with chromium coating and base material. The specimens were oxidized at the air under 1250 K during 48 h. Investigations into steel-chromium coating interface were carried out and the structure of cinder was studied. Refs. 7, figs. 2

  8. Evaluation of flexural bond strength of porcelain to used nickel-chromium alloy in various percentages

    Directory of Open Access Journals (Sweden)

    VNV Madhav

    2012-01-01

    Fresh nickel-chromium alloy shows the greatest porcelain adherence.There is no significant change in bond strength of ceramic to alloy with up to 75% of used nickel-chromium alloy.At least 25%- of new alloy should be added when recycled nickel-chromium alloy is being used for metal ceramic restorations.

  9. 75 FR 60454 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Science.gov (United States)

    2010-09-30

    ... AGENCY Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the..., ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated Risk..., 2010. The listening session on the draft assessment for hexavalent chromium will be held on November...

  10. 76 FR 20349 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Science.gov (United States)

    2011-04-12

    ... AGENCY Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the..., ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated Risk... workshop on the draft assessment for Hexavalent Chromium will be held on May 12, 2011, beginning at 8:30...

  11. 77 FR 61431 - Hexavalent Chromium Standards; Extension of the Office of Management and Budget's (OMB) Approval...

    Science.gov (United States)

    2012-10-09

    ... Occupational Safety and Health Administration Hexavalent Chromium Standards; Extension of the Office of...) approval of the information collection requirements specified in the Hexavalent Chromium Standards for... requirements specified in the Hexavalent Chromium (Cr(VI)) Standards for General Industry (29 CFR...

  12. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  13. Speciation dependent radiotracer studies on chromium preconcentration using iron doped calcium alginate biopolymer

    International Nuclear Information System (INIS)

    The work aims to study the differential attitude of Ca-alginate (CA) and Fe-doped calcium alginate (Fe-CA) and towards Cr(III) and Cr (IV) so that, depending on the oxidation state of chromium effluent, environmentally sustainable methodologies can be prescribed for removal of chromium. Throughout the experiment 51Cr has been used as the precursor of stable chromium

  14. 40 CFR 749.68 - Hexavalent chromium-based water treatment chemicals in cooling systems.

    Science.gov (United States)

    2010-07-01

    ... Cooling Systems § 749.68 Hexavalent chromium-based water treatment chemicals in cooling systems. (a... distribution in commerce of hexavalent chromium-based water treatment chemicals for use in cooling systems. (d... holds hexavalent chromium-based water treatment chemicals for use in cooling systems. (6) Cooling...

  15. Chromium supplementation alters both glucose and lipid metabolism in feedlot cattle during the receiving period

    Science.gov (United States)

    Crossbred steers (n = 20; 235 +/- 4 kg) were fed 53 days during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brandChromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0...

  16. Enhancement of the acute phase response to lipopolysaccharide (LPS) challenge in steers supplemented with chromium

    Science.gov (United States)

    The study examined the effect of chromium supplementation on the response of steers to an LPS challenge. Twenty steers received a premix that added 0 (control) or 0.2 mg/kg of chromium (KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) to the total diet on a dry matter basis for 55 d. Steer...

  17. Chromium supplementation alters the glucose and lipid metabolism of feedlot cattle during the receiving period

    Science.gov (United States)

    Crossbreed steers (n = 20; 235 ± 4 kg) were fed 53 d during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brand Chromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0 (C...

  18. Soil dehydrogenase activity in the presence of chromium (III) and (VI)

    OpenAIRE

    Wolińska A.; Stępniewska Z.

    2005-01-01

    The paper presents the influence of chromium forms (III) and (VI) on the soil dehydrogenase activity. Enzyme activities can be considered effective indicators of soil quality changes resulting from environmental stress or management practices. It was found that chromium compounds have detrimental effects on soil dehydrogenase activity. After the addition of chromium, a rapid and significant decrease in enzymatic activities was observed.

  19. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Science.gov (United States)

    2010-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  20. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  1. Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

    Energy Technology Data Exchange (ETDEWEB)

    Ivanauskas, Remigijus; Samardokas, Linas [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu str. 19, Kaunas LT-50254 (Lithuania); Mikolajunas, Marius; Virzonis, Darius [Department of Technology, Kaunas University of Technology, Panevezys Faculty, Daukanto 12, 35212 Panevezys (Lithuania); Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2014-10-30

    Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N{sub 2} at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N{sub 2} at 100 °C, polycrystalline PA-Tl{sub x}Se{sub y} composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials.

  2. Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

    International Nuclear Information System (INIS)

    Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N2 at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N2 at 100 °C, polycrystalline PA-TlxSey composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials

  3. Hot corrosion resistance of nickel-chromium-aluminum alloys

    Science.gov (United States)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  4. Primary and secondary crystallization of modified hypoeutectic chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2010-04-01

    Full Text Available The paper presents investigations of crystallization of modified hypoeutectic wear resistant chromium cast iron which contains carbon about 2% and chromium on three levels (12%, 18% and 25%. Three substances were applied to the modification ( boron carbide (B4C, ferroniobium (FeNb and mixture of ferroniobium and mischmetal (RE. The investigations of crystallization were conducted the DTA method in DTA-C and DTA-Is testers. The influence on the course of the process of primary and secondary crystallization was observed.

  5. Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium

    International Nuclear Information System (INIS)

    Chromium, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome

  6. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    Directory of Open Access Journals (Sweden)

    B. Arh

    2011-07-01

    Full Text Available The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming slag are discussed.

  7. Possibility of sorption purification of chromium comprising waste waters of galvanic production by inorganic ion exchangers

    International Nuclear Information System (INIS)

    Present work is devoted to possibilities of sorption purification of chromium comprising waste waters of galvanic production by inorganic ion exchangers. Thus, the comparative study of sorption of chromium ions on anion exchanger A B-17 and on inorganic ion exchangers on the basis of hydrated titanium and zirconium dioxides in static and dynamic conditions is conducted. The influence of chromium ions concentration, solutions acidity (ph=1÷12) and presence of base electrolyte on sorption is studied. The state of chromium ions sorbed by inorganic ion exchangers is studied by means of infrared spectroscopy and spectroscopy. It is defined that inorganic sorbents could be used for chromium extraction from different solutions.

  8. Half life of chromium in serum and urine in a former plasma cutter of stainless steel

    OpenAIRE

    Petersen, R.; Thomsen, J. F.; Jorgensen, N. K.; Mikkelsen, S

    2000-01-01

    For 8 years chromium in serum and urine has been followed up in a former plasma cutter of stainless steel who was exposed to airborne dust and fumes containing chromium during this work. After the first examination for serum chromium the exposure ended. Serum chromium concentration has been measured seven times during the period and was initially very high and has subsequently dropped slowly. The half life was 40 months in serum. Urinary chromium has been measured five times. The half life wa...

  9. Reactor target from metal chromium for "pure" high-intensive artificial neutrino source

    Science.gov (United States)

    Gavrin, V. N.; Kozlova, Yu. P.; Veretenkin, E. P.; Logachev, A. V.; Logacheva, A. I.; Lednev, I. S.; Okunkova, A. A.

    2016-03-01

    The paper presents the first results of development of manufacturing technology of metallic chromium targets from highly enriched isotope 50Cr for irradiation in a high flux nuclear reactor to obtain a compact high intensity neutrino source with low content of radionuclide impurities and minimum losses of enriched isotope. The main technological stages are the hydrolysis of chromyl fluoride, the electrochemical reduction of metallic chromium, the hot isostatic pressing of chromium powder and the electrical discharge machining of chromium bars. The technological stages of hot isostatic pressing of chromium powder and of electrical discharge machining of Cr rods have been tested.

  10. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  11. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    Science.gov (United States)

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3). PMID:27483873

  12. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    International Nuclear Information System (INIS)

    (smbullet) Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage (smbullet) Secondary Objective: Reduce hexavalent chromium to 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  13. Intestinal absorption of chromium as affected by wheat bran

    International Nuclear Information System (INIS)

    This study was designed to investigate the influence of dietary fiber, as found in wheat bran, on the absorption of chromium. Twenty male Sprague-Dawley rats were divided into two groups of 10. The control was fed a semi-purified diet containing casein, methionine, cornstarch, sucrose, corn oil, mineral and vitamin mix, and choline bitartrate. The experimental group was fed the same diet but with soft red winter wheat bran added to a level of 35% of the diet at the expense of sucrose. To determine chromium absorption and uptake by selected tissues, rats were fasted for 24 hr, fed 5 g of the respective diet, 2 hr later intubated with 100μCi of Cr-51of sacrificed 24 hr later. The rats wee housed in metabolic cages after the Cr-51 intubation. The addition of wheat brand to the diet did not significantly affect chromium absorption as measured by percent dose of Cr-51 in the 24 hr urine. The percent dose in the control group was 0.68 +/- 0.20% (mean +/- SEM) and in the experimental group 0.63 +/- 0.24% (mean +/-SEM) (N.S.). The cr-51 uptake of liver, spleen, jejunum, and blood was not statistically different between groups. These results indicate that dietary fiber as found in wheat bran does not impair intestinal absorption of chromium

  14. Differents remediation methodos for lead, chromium and cadmium contaminated soils

    International Nuclear Information System (INIS)

    The usage of phosphates in the remediation of plots contaminated with heavy metals appears to be a good strategy to lessen the danger of these metals. This study analyses the effect of the mobilization of: Lead, chromium and cadmium by utilizing diverse forms of phosphates in contaminated soils of three different origins with ph modification and without it

  15. FEATURES OF CHROMIUM DOPING OF WEAR-RESISTANT CAST IRON

    Directory of Open Access Journals (Sweden)

    V. V. Netrebko

    2015-05-01

    Full Text Available The aim of this work analysis of the influence of chromium on the process of carbide formation, changes in chemical composition of the metal substrate in the areas adjacent to the carbides and at the hardness of iron while economy nickel and manganesealloying.

  16. DANGER OF HEXAVALENT CHROMIUM AND STRATEGY FOR THE REMEDITATION

    Directory of Open Access Journals (Sweden)

    Aniruddha Roy

    2013-02-01

    Full Text Available Some metals as micronutrients have a major role in the life and growth process of plants and animals. However, certain forms of some metals may also act as toxic material even in relatively small quantities. Chromium is such a metal, whose concentration above a certain limit may cause a serious problem to the health of living organisms. Chromium (Cr may occur in several chemical forms in organic and inorganic systems. In biological systems only Cr (III and Cr (VI are significant. Among these two states, trivalent chromium (Cr-III is considered as an essential component, while hexavalent Chromium (Cr-VI in biological system has been detected as responsible for so many diseases, even some specific forms of cancer. This paper intends to present the adverse effect of Cr(VI on environment as well as on human beings and also try to find a way out to dissolve the problem by a newly developed efficient and cost effective technique.

  17. IRIS TOXICOLOGICAL REVIEW OF HEXAVALENT CHROMIUM (INTERAGENCY SCIENCE CONSULTATION DRAFT)

    Science.gov (United States)

    On Septemeber 30, 2010, the draft Toxicological Review of Hexavalent Chromium and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agenc...

  18. Chromium toxicity to nitrifying bacteria: implications to wastewater treatment

    Science.gov (United States)

    Chromium, a heavy metal that enters wastewater treatment plants (WWTPs) through industrial discharges, can be toxic to microorganisms carrying out important processes within biological wastewater treatment systems. The effect of Cr(III) and Cr(VI) on ammonia dependent specific ox...

  19. Electrochemistry of active chromium. Part III. Effects of temperature

    Directory of Open Access Journals (Sweden)

    J. P. POPIC

    2003-11-01

    Full Text Available It was shown that the temperature in the range 20 – 65 ºC has considerable effects on the electrochemical anodic dissolution of chromium in the active potential range as well as on the electrochemical hydrogen evolution reactions on bare and oxide covered chromium surfaces. Also, the chemical dissolution of chromium is strongly affected. The apparent energy of activation for anodic dissolution is 63.1 kJ mol-1, for hydrogen evolution on a bare Cr surface 19.5 kJ mol-1, for the same reaction on an oxide covered surface 44.0 kJ mol-1 and for the chemical (“anomalous” dissolution 66.9 kJ mol-1. The temperature dependences of the total corrosion rate, and the electrochemical corrosion rate alone, are presented in polynomial forms with the appropriate constants obtained by the best fit of the experimental data. For the hydrogen evolution reaction on both bare and oxide covered chromium, the Volmer-Heyrovsky reaction mechanism with the second step as rate determining was proposed.

  20. 76 FR 8773 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2011-02-15

    ... applicable deadline.'' (75 FR 80457). Accordingly, pursuant to section 751(c) of the Tariff Act of 1930 (19 U... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... Japan would be likely to lead to continuation or recurrence of material injury. On December 22,...

  1. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... superalloy degassed chromium from Japan (70 FR 76030). The Commission is conducting a review to determine..., subparts A, D, E, and F (19 CFR part 207), as most recently amended at 74 FR 2847 (January 16, 2009). \\1... rule 201.15(b)(19 CFR 201.15(b)), 73 FR 24609 (May 5, 2008). This advice was developed in...

  2. Microbial biotechnology for remediation of aquatic habitats polluted with chromium

    Directory of Open Access Journals (Sweden)

    Viorica Coşier

    2008-12-01

    Full Text Available Chromium may occur in nine different forms of oxidation ranging from ?II to +VI, with forms II, III and VI as the most commonly encountered. In Cluj county, chromium pollution dates well back in time and has caused important dysfunction to the mechanical-biological wastewater purification station of the city of Cluj (Coşier & Diţă 1996. The purpose of this study was to develop one microbial method able to reduce hexavalent chromium (mobile, permeable to cell membrane, carcinogenic and mutagenic (Ishikawa et al 1994 to the trivalent form (insoluble and an essential element for humans (Song et al 2006. Different sources of chromium-reducing bacteria and many sources of carbon and energy added to the Kvasnikov mineral basal medium (Komori et al 1990 with increasing amount of chromate (200- 1000 mg/l were tested. Two bacterial strains, able to reduce even 1000 mg chromate/l, were isolated in pure culture. For one of these bacterial strains, we determined the optimum conditions for the reduction of Cr (VI.

  3. Developing of chromium cast steel on sleeves of heavy machines

    Directory of Open Access Journals (Sweden)

    J. Kilarski

    2010-10-01

    Full Text Available The results of investigations of hardness, impact resistance, abrasive and corrosive wear of selected chromium cast steel with destination on sleeves of heavy machines were introduced in the article. First results of exploational investigations talked over on the end.

  4. Production performance of quails given chromium organic in ration

    Directory of Open Access Journals (Sweden)

    Deden Sudrajat

    2014-12-01

    Full Text Available Egg production of quails depends on quality of ration. Nutrient manipulation by chromiun inclusion in ration is a possible way to improve production. It is known that chromium mineral in form of GTF in blood has a role not only in enhancement of glucose entering cells through improvement of insulin activity but also in metabolism of lipid and synthesis of protein and elimination of heat stress to improve egg production. This study aimed at assessing egg production of quails fed ration containing chromium-yeast. Sixty-four quails aged 40 days were used. A completely randomized design with 4 treatments and 4 replication was applied in this study. Treatment consisted of commercial ration + Cr 0 ppm (R1, commercial ration + Cr 0.5 ppm (R2, commercial ration + Cr 1 ppm (R3, and commercial ration+ Cr 1.5 ppm (R4. Measurements were taken on feed intake, egg weight, egg mass production, hen day, feed conversion rate, egg index, and egg shell thickness. Results showed that A ration containing organic chromium as much as 1,5 ppm did not affect feed intake, egg production, egg weight, and eggshell thickness, however lowered feed conversion rate by up to 32.25% from that of control. Supplementation of 0,5 ppm chromium in the ration lowered the value of eggs index in the fourth week.

  5. New alloys to conserve critical elements. [replacing chromium in steels

    Science.gov (United States)

    Stephens, J. R.

    1978-01-01

    Previous studies and surveys on availability of domestic reserves have shown that chromium is a most critical element within the U.S. metal industry. More precisely, the bulk of chromium is consumed in the production of stainless steels, specifically Type 304 stainless steel (304SS) which contains 18% Cr. The present paper deals with means of reducing chromium in commercial stainless steels by substituting more abundant or less expensive elements with the intent of maintaining the properties of 304SS. The discussion focuses on some of the oxidation and corrosion properties of new substitute stainless steels with only 12% Cr, which represents a potential saving of 33% of the chromium consumed in the production of 304SS. The alloying elements substituted for Cr in 304SS are selected according to their potential for protective oxide formation during high-temperature oxidation; these are Al, Si, Ti, Y, and misch metal which is 99.7% rare-earth metals containing 50 to 55% cerium. Other alloying elements to impart corrosion resistance are Mn, Mo, and V.

  6. Discovery of Chromium, Manganese, Nickel, and Copper Isotopes

    OpenAIRE

    Garofali, K.; Robinson, R; Thoennessen, M

    2010-01-01

    Twenty-seven chromium, twenty-five manganese, thirty-one nickel and twenty-six copper isotopes have so far been observed and the discovery of these isotopes is discussed. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  7. Invariant coefficients of diffusion in iron-chromium-nickel system

    Energy Technology Data Exchange (ETDEWEB)

    Mokrov, A.P.; Akimov, V.K.; Golubev, V.G.

    1984-02-01

    The temperature and concentration dependences of the Dsub(c) coefficients in the ..gamma..-phase of iron-chromium-nickel system are determined. It is proposed to described mutual diffusion in multicomponent systems using invariant, i.e. independent of the choice of solvent, coefficients of diffusion. The assumption that their temperature dependence follows the Arrhenius law is confirmed by the experiment.

  8. Invariant coefficients of diffusion in iron-chromium-nickel system

    International Nuclear Information System (INIS)

    The temperature and concentration dependences of the Dsub(c) coefficients in the γ-phase of iron-chromium-nickel system are determined. It is proposed to described mutual diffusion in mul-- ticomponent systems using invariant, i. e. independent of the choice of solvent, coefficients of diffusion. The assumption that their temperature dependence follows the Arrhenius law is confirmed by the experiment

  9. Friction and wear behavior of chromium carbide coatings

    International Nuclear Information System (INIS)

    Chromium carbides, tungsten carbide, and chromium oxide have been tested and evaluated as coatings to protect high-temperature gas-cooled reactor (HTGR) steam generator and other HTGR components from adhesion, galling associated with sliding wear or from fretting. Tests were performed in commercially-pure helium and in helium doped with various gaseous impurities (H2, H2O, CH4, CO) to simulate the primary coolant of an HTGR. Several types of chromium carbide coatings including Cr3C2, Cr7C3, and Cr23C6, were tested for wear resistance and resistance to long-term spalling. Tungsten carbide and chromium oxide coatings were tested in sliding wear tests. Cr23C6-NiCr coatings showed the best performance (from 400 to 8160C) whether they were applied by detonation gun or plasma gun spraying methods. The presence of the Cr23C6-NiCr coatings did not affect the creep rupture properties of Alloy 800H substrates at temperatures up to 7600C. Low-cycle fatigue life of similar specimens at 5930C was reduced to 10 to 20% when tested in the 1 to 0.6% strain range

  10. Porosity of detonation coatings on the base of chromium carbide

    International Nuclear Information System (INIS)

    Porosity of detonation coatings on the base of chromium carbide is estimated by the hydrostatic weighing. The open porosity value dependence on the distance of spraying, depth of the charge, ratio and volume of the detonator barrie filing with gas components is established. Pore distribution in the cross section of a specimen tested for porosity is studied by the methods of metallographic analysis

  11. The chromium accumulation and its physiological effects in juvenile rockfish, Sebastes schlegelii, exposed to different levels of dietary chromium (Cr(6+)) concentrations.

    Science.gov (United States)

    Kim, Jun-Hwan; Kang, Ju-Chan

    2016-01-01

    Juvenile rockfish (mean length 13.7±1.7 cm, and mean weight 55.6±4.8 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr(6+)) at 0, 30, 60, 120 and 240 mg/kg. The profile of chromium in the tissues of rockfish is dependent on the exposure periods and chromium concentration. After 4 weeks, the order of chromium accumulation in tissues was liver>kidney>spleen>intestine>gill>muscle. The dietary chromium exposure decreased the growth rate and hepatosomatic index of rockfish. The major hematological findings were significant decrease in the red blood cell (RBC) count, hematocrit (Ht) value, and hemoglobin (Hb) concentration exposed to ≥120 mg/kg chromium concentrations. The dietary chromium exposure (≥120 mg/kg) led to notable increase in glucose, cholesterol, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) in plasma, whereas there was no considerable change in calcium, magnesium, total protein, and alkaline phosphatase (ALP). The results indicated that the dietary chromium exposure to rockfish can induce significant chromium accumulation in the specific tissues, inhibition of growth, and hematological alterations. PMID:26705966

  12. Structure and morphology studies of chromium film at elevated temperature in hypersonic environment

    Indian Academy of Sciences (India)

    G M Hegde; V Kulkarni; M Nagaboopathy; K P J Reddy

    2012-06-01

    This paper presents the after shock heated structural and morphological studies of chromium film coated on hypersonic test model as a passive drag reduction element. The structural changes and the composition of phases of chromium due to shock heating (2850 K) are characterized using X-ray diffraction studies. Surface morphology changes of chromium coating have been studied using scanning electron microscopy (SEM) before and after shock heating. Significant amount of chromium ablation and sublimation from the model surface is noticed from SEM micrographs. Traces of randomly oriented chromium oxides formed along the coated surface confirm surface reaction of chromium with oxygen present behind the shock. Large traces of amorphous chromium oxide phases are also observed.

  13. Contribution of photoelectron spectrometry and infrared spectrometry to the study of various oxidised forms of chromium

    International Nuclear Information System (INIS)

    Securate knowledge of internal surface of primary coolant circuits of PWR is required for an estimation of dissolution of used materials and for estimation of decontamination efficiency. The binding energies of various electron levels of chromium were determined by photoelectron spectrometry (ESCA), both for the metal and for certain compounds. Because of the intensities of the signals obtained the 2 p 3/2 level alone can be used for analytical purposes. Owing to a possible interference between this level due to hexavalent chromium and a satellite peak caused by trivalent chromium the method is not able to show up small amounts of chromium VI in chromium III. Simultaneous detection of the hexavalent and trivalent forms was achieved by infrared spectrometry. The problem of revealing traces of chromium VI in surface layers of trivalent chromium oxide has thus been solved

  14. The new mineral species brodtkorbite, Cu2HgSe2, and the associated selenide assemblage from Tuminico, Sierra de Cacho, La Rioja, Argentina

    International Nuclear Information System (INIS)

    Brodtkorbite, ideally Cu2HgSe2, a new mineral species, occurs in a telethermal selenide vein-type assemblage at the Tuminico Ia selenium deposit, Sierra de Cacho (Sierra de Umango) district, La Rioja, Argentina. The selenide assemblage also contains berzelianite, bellidoite, cadmoselite (mercurian, cuprian), chameanite, crookesite, eskebornite, eucairite, ferroselite, hakite, klockmannite, a luanheite-type phase, trogtalite-krutaite, tiemannite, tyrrellite, umangite and uraninite. Minor constituents are undefined phases that belong to the Cd-(Cu)-Hg-Se and (Co,Ni,Cu)-As-Se systems. The selenides occur as veinlets, as impregnations and as massive ores in calcite veins, and are hosted by altered (hematite-stained) amphibolites of the Sierra de Pampeanas, the Precambrian basement of the Precordillera terrane. Brodtkorbite was observed as anhedral grains; they range in size from 10 X 20 up to 50 X 100 μm and as aggregates of composite grains up to 150 X 250 μm, commonly intergrown with berzelianite, tiemannite and (rarely) umangite and clausthalite. The mineral is dark grey, opaque, has a metallic luster, and a dark grey streak. VHN10 ranges from 91.4 to 131 (mean 118) kg/mm2, which corresponds to a calculated Mohs hardness of about 2 1/2 to 3. The density is 7.77 g/cm3 and was calculated for the ideal formula with Z = 2, In plane-polarized reflected light, the mineral is white, is weakly to moderately pleochroic from pinkish to bluish white, and lacks internal reflections. It has a weak to strong bireflectance; the anisotropy is weak to strong with rotation tints from mauve-grey to yellowish grey. The reflectance spectra and color values in air and in oil are tabulated. The chemical composition, which was obtained with an electron microprobe, shows very little variation within individual grains and between grains. The average composition is: Cu 26.2, Hg 40.7, Se 32.9, total 99.8 wt%. This leads to an empirical formula (total atoms = 5) of Cu2.00Hg0.98Se2

  15. Laboratory scale studies on removal of chromium from industrial wastes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr 3+) and hexavalent (Cr 6+) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr3+ is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases.In phase I, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase II showed that lower dose of sodium meta bisulfate was sufficient to obtain 100 % efficiency in reducing Cr6+ to Cr3+, and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents.Phase III studies indicated the best pH was 8.5 for precipitation of Cr 3+ to chromium hydroxide by using lime. An efficiency of 100 % was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase IV actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100 % efficiency at a settling time of 30 minutes and confirmed that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.

  16. Sorption of chromium in soils of the Cerrado Goias, Brazil

    Directory of Open Access Journals (Sweden)

    Welershon José de Castro

    2010-08-01

    Full Text Available Land application of tannery sludge, which usually contain high levels of chromium, and considerable amounts of organic matter, macronutrients and micronutrients may contribute to the improvement of soil fertility and plant nutrition, and constitutes a form of disposal residue in the environment. The objective of this work was to determine the sorption isotherms of metal chromium (Cr+3 in a Ultisol, Oxisol Typic Acrustox, Quartzipsamment and Kandic Oxisol, identify soil classes that are prone to chromium mobility, and characterize the potential of agricultural soils of Goiás that are subject to groundwater contamination by the potentially toxic metal. For the establishment of sorption isotherms, solutions were prepared at 1:10 in volume. Air dried samples of 5.0 cm3 of each class of soil were placed in triplicates in beakers of 250.0 cm3. A solution containing 50.0 cm3 of the potentially toxic metal was added to solution. The solutions were prepared in CaCl2.(2H2O (0.01 mol.L-1 as electrolyte support and employing the basic chromium sulphate as a source of metal. Adjustments were made to the polynomial regression between the concentrations of potentially toxic levels of metal contaminants in the solution depending on the concentration of metal in the filtered solution after equilibrium. The Quartzipsamment showed lower retention compared to other classes of soils. Therefore it is more vulnerable to groundwater contamination if industrial wastes containing trivalent chromium are used as fertilizer.

  17. Phase equilibria in the uranium-chromium-carbon system

    International Nuclear Information System (INIS)

    The alloys for this study (40 different compositions) were prepared by melting a charge comprising appropriate amounts of the various components and a 'master' alloy under an argon atmosphere on a water-cooled copper tray in an arc furnace equipped with a tungsten electrode. The starting components were uranium of 99.7% purity, graphite with an 0.004% ash content and electrolytically prepared chromium. The alloys were analysed by X-ray spectroscopy, X-ray diffraction analysis and microstructural methods, and a selective chemical analysis was made. As a result of these studies, a new compound of composition 45 at.%Cr - 10 at.%U - 45 at.%C was found; it was subjected to X-ray diffraction analysis. The composition of the compound x(UCr2C3) was refined. The crystallization characteristics of the alloys were established over the entire composition range, a diagram of the non- and monovariant equilibria was drawn and the section for the sub-solidus temperature was constructed over the entire range of concentrations. The isothermal section at 1500-16000C was constructed for the UC2-UC-UCrC2 region; this is characterized by a broad region consisting of a homogeneous solid solution of chromium in the high-temperature (UC-β-UC2) solid solution, which the chromium stabilizes down to a lower temperature. The observed increase of the carbon content in the solid solution with increase in the content of iron can apparently explain the improvement of chromium-modified monocarbide nuclear fuel reported in the literature. The carbon content in uranium-based monocarbide fuel can be increased to approximately 55 at.% by the addition of approximately 7 at.% chromium without change in the crystal structure. The parameters of the tetragonal (UC-β-UC2) lattice were determined to be a=5.041 A and c=5.128 A

  18. Raman spectroscopy of supported chromium oxide catalysts : determination of chromium-oxygen bond distances and bond orders

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    An empirical correlation is described for relating Raman stretching frequencies of chromium—oxygen (Cr—O) bonds to their bond lengths in chromium oxide reference compounds. An exponential fit of crystallographically determined Cr—O bond lengths to Cr—O Raman symmetric stretching frequencies (800–130

  19. Reduction of hexavalent chromium by ferrous iron: A process of chromium isotope fractionation and its relevance to natural environments

    DEFF Research Database (Denmark)

    Døssing, Lasse Nørbye; Dideriksen, Knud; Stipp, Susan Louise Svane;

    2011-01-01

    Stable chromium (Cr) isotopes can be used as a tracer for changing redox conditions in modern marine systems and in the geological record. We have investigated isotope fractionation during reduction of Cr(VI)aq by Fe(II)aq. Reduction of Cr(VI)aq by Fe(II)aq in batch experiments leads to significant...

  20. The effect of dietary supplementation with different forms and levels of organic chromium on broilers meat quality

    OpenAIRE

    Keleman Svetlana P.; Kevrešan Slavko E.; Supić Boriša; Perić Lidija; Strugar Vladimir

    2006-01-01

    This paper deals with the effect of supplementation with the three different preparations of organic chromium complexes: the ethylenediaminetetraacetic acid complex with chromium; chromium (III)­lysine and chromium picolinate, on broilers meat quality. In every preparation supplementing broilers diet chromium was present at the three different levels: 0.2; 0.4 and 0.6 mg/kg. The meat quality was monitored with respect to the following parameters: the contents of fat, protein, minerals and wat...

  1. Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

    Science.gov (United States)

    Izbicki, J.A.; Ball, J.W.; Bullen, T.D.; Sutley, S.J.

    2008-01-01

    Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 ??g/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 ??g/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 ??g/L at pH < 7.5 regardless of geology. ??53Cr values in native ground-water ranged from 0.7 to 5.1??? and values were fractionated relative to the average ??53Cr composition of 0??? in the earth's crust. Positive ??53Cr values of 1.2 and 2.3??? were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. ??53Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing ??53Cr values were observed as dissolved O2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest ??53Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. ??53Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from -0.1 to 3.2???. Near zero ??53Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased ??53Cr values at the site. Although ??53Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the ??53Cr values in conjunction with major-ion data, and the ??18O and ??D composition of water from wells.

  2. a Study of Volatile Precursors for the Growth of Cadmium Sulphide and Cadmium Selenide by Metal Organic Chemical Vapour Deposition.

    Science.gov (United States)

    Beer, Michael P.

    Available from UMI in association with The British Library. The wide-band-gap semiconductors, cadmium sulphide and cadmium selenide, may be grown by Metal Organic Chemical Vapour Deposition (MOCVD). This method typically involves the reaction of gaseous streams of Me_2 Cd and H_2Y (Y = S, Se) over a heated substrate (usually gallium arsenide) on which the desired compound is grown as an epitaxial layer. Unfortunately, the precursors start to react in the cold zone of the reactor, that is before they reach the heated substrate. This problem is known as prereaction. The problem of prereaction is partially reduced by the use of adducts of dimethyl cadmium in place of the free dialkyl compound although the mechanism by which such adducts block prereaction is unknown. Accordingly, a study of adducts of dimethyl cadmium was undertaken with a view to determining their properties in all phases. The adduct of Me_2Cd with 2,2^ '-bipyridyl was found to be monomeric in the solid state while that with 1,4-dioxane, a volatile compound used for prereaction reduction, was found to be polymeric. A study of adducts in the gas phase using mass spectrometry and gas phase Fourier transform infrared spectroscopy gave no evidence to suggest there is any gas phase association between 1,4-dioxane and dimethyl cadmium. With the 2,2 ^'-bipyridyl adduct some evidence for partial retention of coordinate bonds upon sublimation was obtained. The solid adduct of Me _2Cd with N,N,N^' ,N^'-tetramethylethylenediamine (TMEDA) was prepared as it was hoped that the flexibility of the aliphatic Lewis base would permit the formation of an adduct containing strong co-ordinate bonds which would remain intact upon sublimation. Using gas phase electron diffraction, the structure of the adduct of Me_2Cd and TMEDA was determined. It was shown to exist in the gas phase purely as the associated monomeric species. The adduct was then employed for the growth of CdS and CdSe in an industrial MOCVD apparatus. The

  3. Effect of recasting on the thickness of metal-ceramic interface of nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2008-01-01

    Full Text Available Introduction/Aim. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the thickness of their metal-ceramic interface in making fixed partial dentures. Metal-ceramic interface determines their functional integrity and prevents damages on ceramics during mastication. Investigation of metal-ceramic samples is supposed to show if base metal alloys for metalceramics are successfully recycled without any risk of reduction of metal-ceramic interface thickness. Methods. The research was performed as an experimental study. Per six metal-ceramic samples of nickel-chromium alloy (Wiron99 and cobalt-chromium alloy (Wirobond C were made each. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Analysis Energy Dispersive X-ray (EDX (Oxford Instruments and Scanning Electon Microscop (SEM analysis (JEOL were used to determine thickness of metal-ceramic interface together with PC Software for quantification of visual information's (KVI POPOVAC. Results. Results of this research introduced significant differences between thickness of metal-ceramic interface in every examined recycle generation. Recasting had negative effect on thickness of metal-ceramic interface of the examined alloys. This research showed almost linear reduction of elastic modulus up to the 12th generation of recycling. Conclusion. Recasting of nickel-chromium and cobaltchromium alloys is not recommended because of reduced thickness of metal-ceramic interface of these alloys. Instead of recycling, the alloy residues should be returned to the manufacturers.

  4. Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: a mechanisms for chromium resistance.

    Science.gov (United States)

    Pereira, M; Bartolomé, M C; Sánchez-Fortún, S

    2013-10-01

    Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M(wt)) and Cr(III)-tolerant (Dc1M(Cr(III)R30)) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC₅₀(₇₂) values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism. PMID:23810518

  5. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys

    Institute of Scientific and Technical Information of China (English)

    Bo Chen; Gang Xia; Xin-Ming Cao; Jue Wang; Bi-Yao Xu; Pu Huang; Yue Chen; Qing-Wu Jiang

    2013-01-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of 〈 1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of 〈1, 1 to 〈3 and 3 to 〈6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  6. A Study of the High Temperature on Chromium Carbide

    International Nuclear Information System (INIS)

    The oxidation rates of chromium carbide have been measured at 900 to 1300 .deg. C and oxygen pressures between 2x10-2 8 x 10-2 Pa using thermogravimetric analysis method. Oxidation behavior of chromium carbide appeared to change very sensitively with both temperature and oxygen pressure. In case with the oxygen pressure lower than 8 x 10-2 Pa, the weight gain in the specimen due to the formation of chromium oxide occurred linearly with time at the every temperature studied, but when the oxygen pressure was increased up to 8 x 10-2Pa, the weight gain behavior versus time showed entirely different tendency. That is, in the temperature range of 900 .deg. C to 1000 .deg. C weight gain occurred, however in the range of 1000 .deg. C to 1300 .deg. C weight lost was observed. The reason for the observed linear kinetics could be inferred as follows. As the oxidation of carbide proceeded carbon monoxide would build up at the interface of the chromium oxide and carbide. If the equilibrium pressure of carbon monoxide at the interface exceeds the gas pressure at the outer specimen surface, the oxide scale formed on it might be cracked exposing new carbide sites on which oxidation could occur successively. Through a thermodynamic consideration it was judged that the above deduction was reasonable. On the other hand, the weight lost mentioned above was explained that it could occur mainly due to the further oxidation of Cr2O3 to the volatile CrO3 at the corresponding experimental conditions. Weight loss phenomenon mentioned before which was observed in the oxidation of chromium carbide was also clearified by X-ray diffraction method and SEM. That is, at 900 .deg. C stable oxide of chromium, (Cr2O3) was identified easily on the specimen surface. However, at 1300 .deg. C, only a few amount of this stable oxide could be found on to specimen surface, indicating Cr2O3 had been evaporated to CrO3 gas

  7. Investigation of the surface composition of electrodeposited black chromium by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Survilienė, S., E-mail: sveta@ktl.mii.lt; Češūnienė, A.; Jasulaitienė, V.; Jurevičiūtė, I.

    2015-01-01

    Highlights: • Black chromium electrodeposited from a Cr(III) bath is composed of oxide, hydroxide and metallic chromium. • Metallic phase is absent in black chromium electrodeposited from a Cr(III) + ZnO bath. • The near-surface layer is rich in hydroxides, whereas oxides of both metals predominate in the depth of the coatings. - Abstract: The paper reviews black chromium electrodeposited from a trivalent chromium bath containing ZnO as a second main component. The chemical compositions of the top layers of the black chromium coatings were studied by the X-ray photoelectron spectroscopy method. The surface of black chromium was found to be almost entirely covered with organic substances. To gain information on the state of each element in the deposit bulk, the layer-by-layer etching of the black chromium surface with argon gas was used. Analysis of XPS spectra has shown that the top layers of black chromium without zinc are composed of various Cr(III) components, organic substances and metallic Cr, whereas metallic Cr is almost absent in black chromium containing some amount of Zn(II) compounds. The ratios of metal/oxide phases were found to be 10/27 and 2/28 for black chromium without and with zinc, respectively. It has been determined that owing to the presence of ZnO in the Cr(III) bath, the percentage of metallic chromium is substantially reduced in black chromium which is quite important for good solar selective characteristics of the coating. The results confirm some of earlier observations and provide new information on the composition of the near-surface layers.

  8. Investigation of the surface composition of electrodeposited black chromium by X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Highlights: • Black chromium electrodeposited from a Cr(III) bath is composed of oxide, hydroxide and metallic chromium. • Metallic phase is absent in black chromium electrodeposited from a Cr(III) + ZnO bath. • The near-surface layer is rich in hydroxides, whereas oxides of both metals predominate in the depth of the coatings. - Abstract: The paper reviews black chromium electrodeposited from a trivalent chromium bath containing ZnO as a second main component. The chemical compositions of the top layers of the black chromium coatings were studied by the X-ray photoelectron spectroscopy method. The surface of black chromium was found to be almost entirely covered with organic substances. To gain information on the state of each element in the deposit bulk, the layer-by-layer etching of the black chromium surface with argon gas was used. Analysis of XPS spectra has shown that the top layers of black chromium without zinc are composed of various Cr(III) components, organic substances and metallic Cr, whereas metallic Cr is almost absent in black chromium containing some amount of Zn(II) compounds. The ratios of metal/oxide phases were found to be 10/27 and 2/28 for black chromium without and with zinc, respectively. It has been determined that owing to the presence of ZnO in the Cr(III) bath, the percentage of metallic chromium is substantially reduced in black chromium which is quite important for good solar selective characteristics of the coating. The results confirm some of earlier observations and provide new information on the composition of the near-surface layers

  9. Internal Friction In The PFN Ceramics With Chromium Dopand

    OpenAIRE

    Zachariasz R.; Bochenek D.; Bruś B.

    2015-01-01

    An aim of this work was to determine an influence of an admixture, the chromium (for x from 0.01 to 0.06), on the mechanical properties of the PFN ceramics. The ceramics with chemical composition Pb(Fe0.5−xCrxNb0.5)O3 was synthesized in two steps from simple oxides PbO, Fe2O3, Nb2O5, Cr2O3. The first stage was based on obtaining the FeNbO4 from the Fe2O3 and Nb2O5 simple oxides. At this stage an admixture in a form the Cr2O3 chromium oxide was added to the solution. In the second stage the Pb...

  10. Hexavalent chromium effects on carbon assimilation in Selenastrum capricornutum

    International Nuclear Information System (INIS)

    One of the difficulties in assessing toxic substances such as metals and complex organic compounds is the duration of the necessary tests. It would be beneficial to have available standardized tests of short duration that would allow a reduction in necessary manpower and overall cost as well as provide a method to evaluate chemicals that are readily degraded (i.e., within a few hours). One method available is the short-term photosynthesis response of algae to a given toxicant. Photosynthesis is not only a critical physiological response but is also one for which standard, accurate methods are available. The 14C method has been used to study the effects of chromium on algae. More recently, it was proposed that the 14C method be used to measure short-term photosynthetic response as a standard algal bioassay. The present study was designed to further evaluate, via photosynthetic response, the potential effects of hexavalent chromium on Selenastrum capricornutum

  11. How to Bypass Verified Boot Security in Chromium OS

    CERN Document Server

    Husain, Mohammad Iftekhar; Qiao, Chunming; Sridhar, Ramalingam

    2012-01-01

    Verified boot is an interesting feature of Chromium OS that should detect any modification in the firmware, kernel or the root file system (rootfs) by a dedicated adversary. However, by exploiting a design flaw in verified boot, we show that an adversary can replace the original rootfs by a malicious rootfs containing exploits such as a spyware and still pass the verified boot process. The exploit is based on the fact that although a kernel partition is paired with a rootfs, verification of kernel partition and rootfs are independent of each other. We experimentally demonstrate an attack using both the base and developer version of Chromium OS in which the adversary installs a spyware in the target system to send cached user data to the attacker machine in plain text which are otherwise inaccessible in encrypted form. We also discuss possible directions to mitigate the vulnerability.

  12. Statistical screening of hexavalent chromium biosorption by Sargassum

    Directory of Open Access Journals (Sweden)

    Abbas Rezaee

    2014-01-01

    Full Text Available The aim of this study was to investigate the statistical screening of hexavalent chromium, Cr (VI, from an aqueous solution using brown seaweed Sargassum as a biosorbent. The biosorption process conditions were evaluated with the statistical screening followed by Plackett-Burman design. The effect of solution pH, contact time, initial chromium and nitrate concentrations were studied. The experimental data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Plackett-Burman design showed the contact time and pH are the most important parameters influencing the Cr (VI biosorption onto Sargassum. The optimum pH, contact time, the initial biosorbent dosage and initial Cr (VI and nitrate concentration were found to be 3, 120 min, 1.3 g, 50 mg/L and 1000 mg/L, respectively. The results indicated that the Freundlich model was the most suitable for Cr (VI biosorption onto Sargassum.

  13. Intragranular Chromium Nitride Precipitates in Duplex and Superduplex Stainless Steel

    OpenAIRE

    Iversen, Torunn Hjulstad

    2012-01-01

    Intragranular chromium nitrides is a phenomenon with detrimental effects on material properties in superduplex stainless steels which have not received much attention. Precipitation of nitrides occurs when the ferritic phase becomes supersaturated with nitrogen and there is insufficient time during cooling for diffusion of nitrogen into austenite. Heat treatment was carried out at between 1060◦C and 1160◦C to study the materials susceptibility to nitride precipitation with...

  14. Identification Trial of Crystallization Parameters of Modified Chromium Cast Iron

    OpenAIRE

    A. Studnicki

    2007-01-01

    In the paper results of researches of abrasion-resisting chromium cast iron inoculated with boron carbide B4C primary crystallization are presented. The main aim of work was make an attempt to identification of crystallization parameters that changed in reason of inoculation. Essential primary crystallization parameters, with the help of which, will be possible to evaluate the inoculation capacity were searched. It was found that in the result of inoculant actions characteristic temperatures ...

  15. Fabrication and characterisation of uranium, molybdenum, chromium, niobium and aluminium

    International Nuclear Information System (INIS)

    This paper describes fabrication of binary uranium alloys by melting and casting. The following alloys with nominal composition were obtained by melting in the vacuum furnace: uranium with niobium contents from 0.5%- 4.0% and uranium with molybdenum contents from 0.4% - 1.2%. Uranium alloys with chromium content from 0.4% - 1.2% and uranium alloy with 0.12% of aluminium were obtained by vacuum induction furnace (electric arc melting)

  16. Recovery of Chromium from Waste Taning Liquors by Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Mahmood M. Barbooti

    2010-10-01

    Full Text Available This is a case study of AL-Za’afaraniya tanning factory, 15 km to the south of Baghdad, to spot light on simple chemical treatment of the discharged water to solve the environmental problems associated with its chromium content management. The treatment was extended to the recovery and reuse of chromium. Chromium was precipitated by the addition of magnesium oxide which also aid as a neutralizer for the acidic effluent. The laboratory treatment was carried out to find the optimum conditions. The wastewater samples were taken from the outline area of the tannery. Box-Wilson method was adopted to find useful relationships between the operating variables (temperature, mixing period and magnesium oxide dose and the pH and chromium content of effluent. The experimental data were successfully fitted to second order polynomial mathematical models for the treatment. The most favorable operating conditions for the treatment were: temperature, 30 ºC; mixing period, 50 min and magnesium oxide concentration, 3000 mg/L. On using the optimum conditions a mathematical model simulating the operation for the treatment was obtained as follows:Cr = 6.0848 – 0.001839 X11 – 0.105334 X12 – 0.041038 X13pH = 10.29086 – 0.001223 X11 – 0.140043 X12 – 0.00953 X13Experimentally Cr concentration was decreased to about (0.5 mg/L in wastewater after raising the pH value to (7.35 by adding magnesium oxide.

  17. Analysis of chromium behaviour and speciation during the electrodialytic process

    OpenAIRE

    Gonçalves, Ana Rita Sarmento

    2015-01-01

    The interest in chromium (Cr) arises from the widespread use of this heavy metal in various industrial processes that cause its release as liquid, solid and gaseous waste into the environment. The impact of Cr on the environment and living organisms primarily depends on its chemical form, since Cr(III) is an essential micronutrient for humans, other animals and plants, and Cr(VI) is highly toxic and a known human carcinogen. This study aimed to evaluate if the electrodialytic process (ED) ...

  18. Soils contaminated with hexavalent chromium : sorption, migration and remediation

    OpenAIRE

    Fonseca, Bruna

    2011-01-01

    The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. In this work, a representative sample of a typical loamy sand soil was collected in Porto, Portugal, in a zone of intensive agriculture activity. This soil was used for a series of tests concerning the adsorption, transport and fate of hexavalent chromium. The adsorption equilibrium and sorption kinetics were evaluated through the fitting of several m...

  19. Bioleaching of hexavalent chromium from soils using acidithiobacillus thiooxidans

    OpenAIRE

    Fonseca, Bruna; Rodrigues, Joana; Queiroz, A.M.; Tavares, Teresa

    2010-01-01

    The continuous and growing degradation of the environment, due to several anthropogenic activities, is a main concern of the scientific community. Consequently, the development of low cost techniques to clean air, water and soils are under intense investigation. In this study, the focused problem is the soil contamination by hexavalent chromium, which is known for its several industrial applications - production of stainless steel, textile dyes, wood preservation and leather tanning - its hig...

  20. Biosorption of Hexavalent Chromium from Aqueous Medium with Opuntia Biomass

    OpenAIRE

    José A. Fernández-López; Angosto, José M.; María D. Avilés

    2014-01-01

    The biosorption of hexavalent chromium from aqueous solutions by Opuntia cladodes and ectodermis from cactus fruits was investigated. Both types of biomass are considered low-cost, natural, and ecofriendly biosorbents. Batch experiments were carried out to determine Cr(VI) biosorption capacity and the efficiency of the biosorption process under different pH, initial Cr(VI) concentration, and sorbent dosage. The biosorption of Cr(VI) by Opuntia biomass was highly pH dependent, favoring higher ...

  1. Low energy magnetic fluctuations in the TSDW phase of chromium

    Energy Technology Data Exchange (ETDEWEB)

    Azuah, R.T. [Hahn-Meitner Inst., Berlin (Germany); Kulda, J. [Inst. Laue Langevin, Grenoble (France); Pynn, R. [Los Alamos National Lab., NM (United States); Stirling, W.G. [Univ. of Liverpool (United Kingdom). Dept. of Physics

    1997-12-01

    A polarized neutron study of chromium carried out in a field of 6T applied to a single-domain single-Q crystal indicates that the inelastic intensity observed close to the transverse spin density wave (TSDW) satellite positions (1 {+-} {delta}, 0,0) does not behave as expected for spin-wave scattering. In particular, the signal corresponds to magnetization fluctuations of almost equal magnitude both parallel and perpendicular to the ordered moments in the TSDW phase.

  2. Characterisation of chromium nitride films produced by PVD techniques

    OpenAIRE

    Barata, A.; CUNHA L.; Moura, C.

    2001-01-01

    Chromium nitride thin films have been deposited on stainless steel substrates by r.f. reactive magnetron sputtering. The influence of process parameters such as substrate bias and partial pressure of reactive gas have been investigated. The characterisation of the coatings was performed by X-ray diffraction (XRD), Raman Spectroscopy (RS) and nano-indentation experiments. These studies allow to analyse the influence of deposition parameters in crystal phases, crystal orientationytextu...

  3. Chromium speciation in solid matrices and regulation: a review.

    Science.gov (United States)

    Unceta, N; Séby, F; Malherbe, J; Donard, O F X

    2010-06-01

    In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na(2)CO(3) solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future. PMID:20099060

  4. Study of Chromium Oxide Activities in EAF Slags

    Science.gov (United States)

    Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

    2016-02-01

    The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

  5. Fretting damage of high carbon chromium bearing steel

    OpenAIRE

    Kuno, Masato

    1988-01-01

    This thesis consists of four sections, the fretting wear properties of high carbon chromium bearing steel; the effect of debris during fretting wear; an introduction of a new fretting wear test apparatus used in this study; and the effects of fretting damage parameters on rolling bearings. The tests were operated under unlubricated conditions. Using a crossed cylinder contact arrangement, the tests were carried out with the normal load of 3N, slip amplitude of 50µm, and frequency of 30Hz ...

  6. Cytokine detection for the diagnosis of chromium allergy *

    OpenAIRE

    Martins, Luis Eduardo Agner Machado; dos Reis, Vitor Manoel Silva

    2013-01-01

    BACKGROUND Patch testing remains the gold standard method for the identification of the etiologic agent of allergic contact dermatitis. However, it is a subjective, time-consuming exam whose technique demands special care and which presents some contraindications, which hamper its use. In a recent study, we showed that the proliferation assay can suitably replace patch testing for the diagnosis of chromium allergy, which had been previously demonstrated only for nickel allergy. In this study,...

  7. Chromium propionate enhances adipogenic differentiation of bovine intramuscular adipocytes

    OpenAIRE

    Rebecca eTokach; Flavio eRibeiro; Ki Yong eChung; Whitney eRounds; Johnson, Bradley J.

    2015-01-01

    In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate on mRNA and protein abundance of different enzymes and receptors. Intramuscular and subcutaneous preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4) and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were treated with diffe...

  8. Chromium Propionate Enhances Adipogenic Differentiation of Bovine Intramuscular Adipocytes

    OpenAIRE

    Tokach, Rebecca J.; Ribeiro, Flavio R. B.; Chung, Ki Yong; Rounds, Whitney; Johnson, Bradley J.

    2015-01-01

    In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate (CrPro) on mRNA and protein abundance of different enzymes and receptors. Intramuscular (IM) and subcutaneous (SC) preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4) and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were t...

  9. The behaviour of chromium in aquatic and terrestrial food chains

    International Nuclear Information System (INIS)

    Chromium has been considered both as potential radioactive and conventional pollutant. Chromium-51 is produced by the activation of 50Cr, which may be present either as a component of steel alloys used in reactors, or in Na2CrO4 added as an anticorrosion agent to the cooling water. Only small amounts of 51Cr are normally found in the liquid waste of nuclear power plants before discharge into rivers. In exceptional situations, however, as a result of the direct release of cooling waters, the aquatic environments may receive relatively large quantities of 51Cr. Part of this 51Cr is adsorbed e.g. to the sediments, but a fraction remains in solution in the river water. Somme accumulation of the radionuclide is observed in fresh water and marine organisms. Therefore, although 51Cr has a relatively short physical half life (27.8d), it is of interest to acquire better information on its accumulation by different species of fresh water organisms and plants, as well as on its behaviour in soils, in order to evaluate the relative importance of this nuclide in the radioactive contamination of the aquatic and terrestrial food chains. As a related and sometimes associated pollutant, stable chromium is also taken into consideration. This element occurs fairly frequently as an environmental pollutant in many countries, either because of its abundance in soils derived from serpentine or because of its release to the environment from industrial wastes. The sequence of presentation of the experiment data is based on the consecutive steps of the contamination process: aquatic environment, soils, plant link of the food chain. Special attention is paid, in the different chapters, to the behaviour of various chemical forms of chromium and to their distribution in different fractions: soluble in water, adsorbed, precipitated on particles or complexed with organic material

  10. Plasma source ion implantation of ammonia into electroplated chromium

    International Nuclear Information System (INIS)

    Ammonia gas (NH3) has been used as a nitrogen source for plasma source ion implantation processing of electroplated chromium. No evidence was found of increased hydrogen concentrations in the bulk material, implying that ammonia can be used without risking hydrogen embrittlement. The retained nitrogen dose of 2.1 x 1017 N-at/cm2 is sufficient to increase the surface hardness of electroplated Cr by 24% and decrease the wear rate by a factor of 4

  11. Occupational Exposure to Chromium of Assembly Workers in Aviation Industries.

    Science.gov (United States)

    Genovese, G; Castiglia, L; Pieri, M; Novi, C; d'Angelo, R; Sannolo, N; Lamberti, M; Miraglia, N

    2015-01-01

    Aircraft are constructed by modules that are covered by a "primer" layer, which can often contain hexavalent chromium [Cr(VI)], known carcinogen to humans. While the occupational exposure to Cr(VI) during aircraft painting is ascertained, the exposure assessment of assembly workers (assemblers) requires investigations. Three biological monitoring campaigns (BM-I,II,III) were performed in an aviation industry, on homogeneous groups of assemblers (N = 43) and controls (N = 23), by measuring chromium concentrations in end-shift urine collected at the end of the working week and the chromium concentration difference between end- and before-shift urines. BM-I was conducted on full-time workers, BM-II was performed on workers after a 3-4 day absence from work, BM-III on workers using ecoprimers with lower Cr(VI) content. Samples were analyzed by atomic absorption spectroscopy and mean values were compared by T-test. Even if Cr concentrations measured during BM-I were lower than Biological Exposure Indices by ACGIH, statistically significant differences were found between urinary Cr concentrations of workers and controls. Despite 3-4 days of absence from work, urinary chromium concentrations measured during BM-II were still higher than references from nonoccupationally exposed populations. In the BM-III campaign, the obtained preliminary results suggested the efficacy of using ecoprimers. The healthcare of workers exposed to carcinogenic agents follows the principle of limiting the exposure to "the minimum technically possible". The obtained results evidence that assemblers of aviation industries, whose task does not involve the direct use of primers containing Cr(VI), show an albeit slight occupational exposure to Cr(VI), that must be carefully taken into consideration in planning suitable prevention measures during risk assessment and management processes. PMID:25793365

  12. Chronic Maternal Dietary Chromium Restriction Modulates Visceral Adiposity

    OpenAIRE

    Padmavathi, Inagadapa J.N.; Rao, K Rajender; Venu, Lagishetty; Ganeshan, Manisha; Kumar, K. Anand; Rao, Ch. Narasima; Harishankar, Nemani; Ismail, Ayesha; Raghunath, Manchala

    2009-01-01

    OBJECTIVE We demonstrated previously that chronic maternal micronutrient restriction altered the body composition in rat offspring and may predispose offspring to adult-onset diseases. Chromium (Cr) regulates glucose and fat metabolism. The objective of this study is to determine the long-term effects of maternal Cr restriction on adipose tissue development and function in a rat model. RESEARCH DESIGN AND METHODS Female weanling WNIN rats received, ad libitum, a control diet or the same with ...

  13. Performance characteristics of mill rolls from graphite chromium cast iron

    OpenAIRE

    Lecomte-Beckers, Jacqueline; Terziev, L.; Breyer, J. P.

    2000-01-01

    The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite...

  14. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    International Nuclear Information System (INIS)

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions

  15. Determination of Chromium(III) Picolinate Using High Performance Liquid Chromatography-Ultraviolet Spectrophotometry

    International Nuclear Information System (INIS)

    Cr-(pic)3 has been widely used as food additives, drugs, and feed additives. Accordingly, its determination method should be established. In the present paper, we have studied the determination method of chromium(III) picolinate accurately using ESI-MS on-lined with HPLC. Chromium(III) picolinate in feed products was determined successfully. Chromium(III) is very well known as an essential mineral. It is suggested as a cofactor in the maintenance of both normal lipid and carbohydrate metabolism by assisting the action of insulin on a cell membrane. According to the National Research Council, the daily recommended intake of chromium(III) is 50-200 μg. Several organic chromium(III) complexes have been reported to have significantly higher absorption and tissue incorporation activity than inorganic salts such as chromium(III) chloride

  16. Chemical composition and structural transformations of amorphous chromium coatings electrodeposited from Cr(III) electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Safonova, Olga V. [Swiss-Norwegian Beamlines at European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Vykhodtseva, Ludmila N. [Department of Electrochemistry, Faculty of Chemistry, Moscow State University, 119991 Moscow (Russian Federation); Polyakov, Nikolai A. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119991 Moscow (Russian Federation); Swarbrick, Janine C. [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Sikora, Marcin [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Department of Solid State Physics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Av. Mickiewicza 30, 30-059 Krakow (Poland); Glatzel, Pieter [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Safonov, Viktor A., E-mail: safon@elch.chem.msu.r [Department of Electrochemistry, Faculty of Chemistry, Moscow State University, 119991 Moscow (Russian Federation)

    2010-12-15

    Amorphous chromium coatings were electrodeposited from Cr(III)-based solutions containing organic (HCOONa) or phosphorus-containing (NaH{sub 2}PO{sub 2}) additives. Their structure was studied by a combination of X-ray diffraction (XRD), valence-to-core X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) at the Cr K-edge. Metalloid atoms (C or P) incorporated in electroplates structure are chemically bonded to chromium (i.e. are located in the first coordination shell). Upon annealing at elevated temperatures in vacuum, these amorphous coatings crystallize into a mixture of phases containing metallic chromium and chromium carbides or chromium phosphides. Quantitative analysis of valence-to-core XES data demonstrates that the average local structure of chromium in the amorphous coatings does not change significantly during crystallization.

  17. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    Science.gov (United States)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  18. Eolian transport of geogenic hexavalent chromium to ground water

    Science.gov (United States)

    Wood, W.W.; Clark, D.; Imes, J.L.; Councell, T.B.

    2010-01-01

    A conceptual model of eolian transport is proposed to address the widely distributed, high concentrations of hexavalent chromium (Cr+6) observed in ground water in the Emirate of Abu Dhabi, United Arab Emirates. Concentrations (30 to more than 1000 μg/L Cr+6) extend over thousands of square kilometers of ground water systems. It is hypothesized that the Cr is derived from weathering of chromium-rich pyroxenes and olivines present in ophiolite sequence of the adjacent Oman (Hajar) Mountains. Cr+3 in the minerals is oxidized to Cr+6 by reduction of manganese and is subsequently sorbed on iron and manganese oxide coatings of particles. When the surfaces of these particles are abraded in this arid environment, they release fine, micrometer-sized, coated particles that are easily transported over large distances by wind and subsequently deposited on the surface. During ground water recharge events, the readily soluble Cr+6 is mobilized by rain water and transported by advective flow into the underlying aquifer. Chromium analyses of ground water, rain, dust, and surface (soil) deposits are consistent with this model, as are electron probe analyses of clasts derived from the eroding Oman ophiolite sequence. Ground water recharge flux is proposed to exercise some control over Cr+6 concentration in the aquifer.

  19. Bioremediation of hexavalent chromium by a cyanobacterial mat

    Science.gov (United States)

    Shukla, Dhara; Vankar, Padma S.; Srivastava, Sarvesh Kumar

    2012-12-01

    The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2-10, 15-30 and 300 ppm at pH 5.5-6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform-infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5-6.2.

  20. Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

    Science.gov (United States)

    Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

    2016-03-01

    Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

  1. Response of soil catalase activity to chromium contamination

    Institute of Scientific and Technical Information of China (English)

    Zofia St(e)pniewska; Agnieszka Woli(n)ska; Joanna Ziomek

    2009-01-01

    The impact of chromium (III) and (VI) forms on soil catalase activity is presented.The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from different depths were used in the experiment.The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control.Catalase activity was assayed by one of the commonly used spectrophotometric methods.As it is demonstrated in the experiment, both Cr(III) and Cr(VI) forms have ability to reduce soil catalase activity.A chromium dose of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control.Catalase activity reached maximum in the soil material from surface layers (0-25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.

  2. Selective Chromium(VI) Ligands Identified Using Combinatorial Peptoid Libraries

    Science.gov (United States)

    Knight, Abigail S.; Zhou, Effie Y.; Pelton, Jeffrey G.; Francis, Matthew B.

    2013-01-01

    Hexavalent chromium (Cr(VI)) is a world-wide water contaminant that is currently without cost-effective and efficient remediation strategies. This is in part due to a lack of ligands that can bind it amid an excess of innocuous ions in aqueous solution. We present herein the design and application of a peptoid-based library of ligand candidates for toxic metal ions. A selective screening process was used to identify members of the library that can bind to Cr(VI) species at neutral pH and in the presence of a large excess of spectator ions. Eleven sequences were identified, and their affinities were compared using titrations monitored with UV-Vis spectroscopy. To identify the interactions involved in coordination and specificity, we evaluated the effects of sequence substitutions and backbone variation in the highest affinity structure. Additional characterization of the complex formed between this sequence and Cr(VI) was performed using NMR spectroscopy. To evaluate the ability of the developed sequences to remediate contaminated solutions, the structures were synthesized on a solid-phase resin and incubated with environmental water samples that contained simulated levels of chromium contamination. The synthetic structures demonstrated the ability to reduce the amount of toxic chromium to levels within the range of the EPA contamination guidelines. In addition to providing some of the first selective ligands for Cr(VI), these studies highlight the promise of peptoid sequences as easily-prepared components of environmental remediation materials. PMID:24195610

  3. Structure and growth of oxide on iron-chromium alloys

    International Nuclear Information System (INIS)

    Several oxides form during the initial stages of oxidation of iron-chromium alloys at 400 to 6000C in CO2-1%CO gas. The nature of the oxidation product depends upon crystallographic orientation and composition of the substrate, and can be explained by considering the maximum solubility of chromium in different oxide phases together with interfacial and strain energy factors. Kinetics of oxidation together with micrographic observations indicate that, as oxidation proceeds spinel oxide M3O4 nucleates at sites on the substrate surface associated with asperities. The spinel nuclei grow laterally and vertically until they coalesce and the scale subsequently thickens according to a parabolic rate law. The duplex structure of scales is interpreted in terms of an outward diffusion of cations together with simultaneous growth of an inner layer in the space created by this outward movement. Scale porosity provides a route for gas-phase transport of oxidant to support the growth of the inner layer. Regularly spaced lamellar voids which may form in the inner layer are believed to be associated with a cyclic vacancy condensation process. Enrichment of the inner layer in chromium is explained by analysis of the possible diffusion path networks in close-packed oxides. Some comments are made concerning possible practical applications of these data. (author)

  4. Design and fabrication of anti-reflection coating on Gallium Phosphide, Zinc Selenide and Zinc Sulfide substrates for visible and infrared application

    Czech Academy of Sciences Publication Activity Database

    Vápenka, David; Václavík, Jan; Mokrý, Pavel

    Cedex: EDP Sciences, 2013 - (Šulc, M.; Kopecký, V.; Lédl, V.; Melich, R.; Skeren, M.), s. 00029. (Book Series: EPJ Web of Conferences. 48). ISSN 2100-014X. [OaM 2012 International Conference on Optics and Measurement. Liberec (CZ), 16.10.2012-18.10.2012] R&D Projects: GA MŠk(CZ) OE10003; GA MŠk(CZ) ED2.1.00/03.0079 Institutional support: RVO:61389021 Keywords : gallium phosphide * zinc selenide * zinc sulfide Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.epj-conferences.org/articles/epjconf/pdf/2013/09/epjconf_OAM2012_00029.pdf

  5. Chromium related degradation of solid oxide fuel cells; Chrom-bezogene Degradation von Festoxid-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Anita

    2011-05-04

    Solid Oxide Fuel Cells (SOFCs) offer a high potential for application as an auxiliary power unit (APU) for heavy goods vehicles as well as combined heat and power (CHP) systems. SOFCs are especially attractive due to their high efficiencies and the use of different fuel types. However, optimization in terms of long term stability and costs are still necessary. This work characterized the degradation of SOFCs with lanthanum strontium manganite (LSM) cathodes under chromium influence. Galvanostatic cell tests were carried out at 800 C with operation times from 250 - 3000 h and variation of the chromium source and current density. The current densities of j = 0 (A)/(cm{sup 2}), j = 0,3 (A)/(cm{sup 2}) and j = 0,5 (A)/(cm{sup 2}) were applied. The high temperature ferritic alloy Crofer22APU was used as a chromium source. Variation of the chromium source was realized by coating the Crofer22APU insert with the chromium retention layer Mn{sub 3}O{sub 4} and the cathode contact layer LCC10. Cell degradation was analyzed with regard to cell voltage, current density and area specific resistance (ASR). Microstructural alterations of the cathode as well as chromium content and distribution across the cell were investigated after completion of the cell tests. For cells with a chromium source present and operation with a nonzero current density, the course of cell degradation was divided into three phases: a run-in, weak linear degradation and strong linear degradation. A decrease of the chromium release rate by means of different coatings stretched the course of degradation along the timescale. Strong degradation, which is characterized by a significant increase in ASR as well as a decrease of current density at the operating point, was only observed when a chromium source in the setup was comb ined with operation of the cell with a non-zero current density. Operation of the cell with a chromium source but no current density caused a degradation of current density at the

  6. Determination of Chromium Content in Human Skin by Means of Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Chromium eczema is a well-known phenomenon in dermatological practice. Different explanations may be given for it. According to one of these the specific texture of the skin of patients is assumed to allow more chromium to pass through the upper layers. As a result, the chromium accumulates faster in the dermis of patients so that a critical value is reached sooner. Another explanation might be that die sensitivity threshold for chromium in patients is lower than in normal persons and can more easily be exceeded. To distinguish between these possibilities and to obtain more information, an investigation was started in which the chromium content in the skin was compared for eczema patients and normal people. The sample weight (10 mg) and the chromium content (0.2 - 0.4 ppm) involved require a sensitive technique. Neutron activation analysis is well suited to this purpose. Under our operation conditions (irradiation time 10 days, neutron flux 1014n/cm2s) it is possible to determine quantities as low as 5 x 10-11 g of chromium. Preliminary experiments show relatively large variations in chromium content of comparable samples, even in skin samples taken from the back of a single person. It is further suggested by the results of these experiments that the chromium content in the skin of eczema patients is lower than in that of normal patients. The results of the analysis may be seriously affected by chromium contamination during sample preparation. Therefore chromium-free instruments must be used. To avoid chromium migration in the skin due to degeneration processes, samples must be taken from persons alive or shortly after their death. (author)

  7. Characteristics of Aerosols Containing Chromium and Nickel From Some Thermal Spraying Operations

    OpenAIRE

    Bohgard, Mats; Welinder, Hans; Akselsson, Roland

    1983-01-01

    Characterization of aerosols, emitted from five methods of thermal spraying with materials containing chromium and nickel were carried out. The characterization procedure includes the determinations of the metal content, the particle size distribution, the oxidation state of chromium and a measure of the solubility of chromium. Three different kinds of samplers and the analytical methods PIXE (Particle Induced X-ray Emission analysis), ESCA (Electron Spectroscopy for Chemical Analysis), AAS (...

  8. Optimization and Modeling of Hexavalent Chromium Removal from Aqueous Solution Via Adsorption on Multiwalled Carbon Nanotubes

    OpenAIRE

    Mina Gholipour; Hassan Hashemipour Rafsanjani; Ataollah Soltani Goharrizi

    2011-01-01

    Hexavalent chromium and its derivatives are potential pollutant due to their mortal affects. Therefore, It is essential to remove these components from wastewaters before disposal. Adsorption can be effective and versatile method for removing of hexavalent chromium. In this article, removal of hexavalent chromium via adsorption on multiwalled carbon nanotubes was investigated as a function of adsorbent dosage, initial solution pH, initial Cr(VI) concentrations, contact time and temperature. T...

  9. Enhancing phytoremediation of chromium-stressed soils through plant-growth-promoting bacteria

    OpenAIRE

    Munees Ahemad

    2015-01-01

    Chromium, specifically hexavalent chromium is one of the most toxic pollutants that are released into soils by various anthropogenic activities. It has numerous adverse effects not only on plant system but also on beneficial soil microorganisms which are the indicators of soil fertility and health. Recent emergence of phytoremediation as an environmental friendly and economical approach to decontaminate the chromium stressed soils has received wider attention. But major drawback of this proce...

  10. Si doped and undoped chromium nitride coatings : a comparative study of physical properties

    OpenAIRE

    CUNHA L.; Moura, C.

    2011-01-01

    Chromium nitride and silicon doped chromium nitride thin films have been deposited by r.f. reactive magnetron sputtering. This study corresponds to the investigation of the influence of processing parameters and of the addition of silicon on the chromium nitride matrix on the properties of the produced films. The characterization of the coatings was performed by X-ray diffraction (XRD), and nano-indentation experiments. Results concerning the crystalline phases, crystal orientation/texture...

  11. Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers

    OpenAIRE

    Fonseca, Bruna; Pazos, M.; Tavares, M. T.; Sanromán, M. A.

    2012-01-01

    PURPOSE: In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this t...

  12. Evaluation of a method for the determination of chromium in urine by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    A method for the determination of chromium in urine by atomic absorption spectrometry, using electrothermic atomization with pyrolytic graphite tubes, is proposed. The determinations are performed by standard addition. The method is applicable to biologic monitoring of populations with different degrees of exposition. It is also used in the analysis of chromium in sediments. Results of chromium in urine of a population group non-exposed to the metal are presented. 11 refs

  13. Chromium does not belong in the diabetes treatment arsenal: Current evidence and future perspectives

    OpenAIRE

    Landman, Gijs WD; Bilo, Henk JG; Houweling, Sebastiaan T.; Kleefstra, Nanne

    2014-01-01

    Chromium is considered to have positive effects on insulin sensitivity and is marketed as an adjunctive therapy for inducing glucose tolerance in cases of insulin resistance (“the glucose tolerance factor”). Case reports on patients who received prolonged parenteral nutrition indeed showed that the absence of trivalent chromium caused insulin resistance and diabetes. However, whether patients with type 2 diabetes can develop a clinically relevant chromium deficiency is unclear. This review su...

  14. Environmental optimization of chromium recovery from tannery sludge using a life cycle assessment approach

    OpenAIRE

    Kiliç, Eylem; Puig Vidal, Rita; Baquero Armans, Grau; Font Vallès, Joaquim; Colak, Selime; Gürler, Deniz

    2011-01-01

    Life cycle assessment (LCA) was used to evaluate the environmental impact of an oxidative chromium recovery method from tannery sludge, in comparison with the usual landfilling process. Three improvement options (water reduction, byproduct use and anaerobic sludge digestion) were considered. The results showed that the proposed chromium recovery process would be better environmentally than conventional landfilling in all the evaluated impact categories if the amount of chromium recovered w...

  15. Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium.

    OpenAIRE

    Gao, M; Levy, L S; Faux, S. P.; AW, T C; Braithwaite, R. A.; Brown, S. S.

    1994-01-01

    OBJECTIVES--Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. METHOD...

  16. Effects of chromic-acid concentration on the structure and properties of chromium coatings

    Energy Technology Data Exchange (ETDEWEB)

    Solodkova, L.N.; Solov' eva, Z.A.; Monev, M.; Nikolova, S.; Rashkov, S.; Dobrev, Ts.

    1987-10-01

    In the interest of decreasing the amount of chromium and other electrolytic effluents that enter the waste stream during chromium electrodeposition processes, and of optimizing plating speeds at reduced chromic acid concentrations, the authors seek to establish the effects of decreasing the chromic acid concentration in the electrolyte on the microstructure, microhardness, internal stress behavior, and tendency toward hydridation of chromium coatings obtained from various electrolyte compositions. Plating kinetics and lattice parameters were also investigated.

  17. Severe insulin resistance treatment with intravenous chromium in septic shock patient

    OpenAIRE

    2012-01-01

    Insulin resistance has been well documented in critically ill patients. Adequate blood sugar control has been associated with better wound healing, and better outcomes in selected patient populations. Chromium is an essential component of human diet. It is believed to affect changes in glucose uptake. Several studies have shown beneficial effects of oral chromium in diabetic patients with insulin resistance, but role of intravenous chromium infusion has not been completely evaluated. We prese...

  18. Chromium picolinate improves insulin sensitivity in obese subjects with polycystic ovary syndrome.

    Science.gov (United States)

    Lydic, Michael L; McNurlan, Margaret; Bembo, Shirley; Mitchell, Lina; Komaroff, Eugene; Gelato, Marie

    2006-07-01

    Trivalent chromium (1000 microg), as chromium picolinate, given without change in diet or activity level, caused a 38% mean improvement in glucose disposal rate in five obese subjects with polycystic ovary syndrome who were tested with a euglycemic hyperinsulinemic clamp technique. This suggests that chromium picolinate, an over-the-counter dietary product, may be useful as an insulin sensitizer in the treatment of polycystic ovary syndrome. PMID:16730719

  19. Tellurides, selenides and Bi-mineral assemblages from the Río Narcea Gold Belt, Asturias, Spain: genetic implications in Cu-Au and Au skarns

    Science.gov (United States)

    Cepedal, A.; Fuertes-Fuente, M.; Martín-Izard, A.; González-Nistal, S.; Rodríguez-Pevida, L.

    2006-07-01

    Gold ores in skarns from the Río Narcea Gold Belt are associated with Bi-Te(-Se)-bearing minerals. These mineral assemblages have been used to compare two different skarns from this belt, a Cu-Au skarn (calcic and magnesian) from the El Valle deposit, and a Au-reduced calcic skarn from the Ortosa deposit. In the former, gold mineralization occurs associated with Cu-(Fe)-sulfides (chalcopyrite, bornite, chalcocite-digenite), commonly in the presence of magnetite. Gold occurs mainly as native gold and electrum. Au-tellurides (petzite, sylvanite, calaverite) are locally present; other tellurides are hessite, clausthalite and coloradoite. The Bi-bearing minerals related to gold are Bi-sulfosalts (wittichenite, emplectite, aikinite, bismuthinite), native bismuth, and Bi-tellurides and selenides (tetradymite, kawazulite, tsumoite). The speciation of Bi-tellurides with Bi/Te(Se + S) ≤ 1, the presence of magnetite and the abundance of precious metal tellurides and clausthalite indicate fO2 conditions within the magnetite stability field that locally overlap the magnetite-hematite buffer. In Ortosa deposit, gold essentially occurs as native gold and maldonite and is commonly related to pyrrhotite and to the replacement of löllingite by arsenopyrite, indicating lower fO2 conditions for gold mineralization than those for El Valle deposit. This fact is confirmed by the speciation of Bi-tellurides and selenides (hedleyite, joséite-B, joséite-A, ikunolite-laitakarite) with Bi/Te(+ Se + S) ≥ 1.

  20. USE OF TWO DIGESTION METHODS IN THE EVALUATION OF CHROMIUM CONTENT IN CATTLE'S MEAT SUPPLEMENTED WITH CHROMIUM CHELATES

    Directory of Open Access Journals (Sweden)

    R. L. T. de Andrade

    2015-06-01

    Full Text Available The present study aimed to analyze the chromium content in beef using two digestion methods. There were used samples from 24 18-month-old male cattle, and twelve of them were supplemented and twelve were not supplemented with chromium chelate. These samples were evaluated by atomic absorption spectroscopy, previously submitted to digestion method using nitric acid (65% with hydrogen peroxide (35% and to digestion method, using solution of nitric perchloric acid in the proportion 3:1. Immediately after the slaughter, the carcasses were sent to sanitary maturation. After 24 hours, samples between 12th and 13th rib in the muscle Longissimus Thoracis were taken. For evaluation, it was used completely randomized design (Die and analysis of variance (ANOVA at 5% of significance level. The results didn't evidenced any significant difference (p>0,05 between the (cromo content, regardless the supplementation. The same happened with the digestion methods used.

  1. Corrosion behavior of HVOF-sprayed and Nd-YAG laser-remelted high-chromium, nickel-chromium coatings

    Science.gov (United States)

    Tuominen, J.; Vuoristo, P.; Mäntylä, T.; Ahmaniemi, S.; Vihinen, J.; Andersson, P. H.

    2002-06-01

    Thermal spray processes are widely used to deposit high-chromium, nickel-chromium coatings to improve high temperature oxidation and corrosion behavior. However, despite the efforts made to improve the present spraying techniques, such as high-velocity oxyfuel (HVOF) and plasma spraying, these coatings may still exhibit certain defects, such as unmelted particles, oxide layers at splat boundaries, porosity, and cracks, which are detrimental to corrosion performance in severe operating conditions. Because of the process temperature, only mechanical bonding is obtained between the coating and substrate. Laser remelting of the sprayed coatings was studied in order to overcome the drawbacks of sprayed structures and to markedly improve the coating properties. The coating material was high-chromium, nickel-chromium alloy, which contains small amounts of molybdenum and boron (53.3% Cr, 42.5% Ni, 2.5% Mo, 0.5% B). The coatings were prepared by HVOF spraying onto mild steel substrates. A high-power, fiber-coupled, continuous-wave Nd:YAG laser equipped with large beam optics was used to remelt the HVOF-sprayed coating using different levels of scanning speed and beam width (10 or 20 mm). Coating that was remelted with the highest traverse speed suffered from cracking because of the rapid solidification inherent to laser processing. However, after the appropriate laser parameters were chosen, nonporous, crack-free coatings with minimal dilution between coating and substrate were produced. Laser remelting resulted in the formation of a dense oxide layer on top of the coatings and full homogenization of the sprayed structure. The coatings as sprayed and after laser remelting were characterized by optical and electron microscopy (OM, SEM, respectively). Dilution between coating and substrate was studied with energy dispersive spectrometry (EDS). The properties of the laser-remelted coatings were directly compared with properties of as-sprayed HVOF coatings.

  2. Progress in the chemistry of chromium(V) doping agents used in polarized target materials

    Energy Technology Data Exchange (ETDEWEB)

    Krumpolc, M. (Illinois Univ., Chicago, IL (USA)); Hill, D. (Argonne National Lab., IL (USA)); Struhrmann, H.B. (Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.). Hamburger Synchrotronstrahlungslabor)

    1990-01-01

    We wish to report progress in two areas of the chromium (V)-based doping agents: Two commonly used chromium (V) complexes, I and II, have been synthesized in perdeuterated form (i.e., all hydrogens replaced by deuterium). They are sodium bis(2-ethyl-2-deuteroxy-butyrato)oxochromate(V)monodeuterate, IV, (acronym EDBA-Cr(V)), and sodium bis(2-deuteroxy-2-methylpropionato)oxochromate(V), III, (acronym DMPA-Cr(V)). A synthetic route leading to the preparation of stable, chromium(III)-free solutions of chromium(V) in diols (1,2-ethanediol/ethylene glycol/and 1,2-propanediol/propylene glycol/) has been outlined.

  3. Improvement on simultaneous determination of chromium species in aqueous solution by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Liao, Y.P.; Jons, O.

    sulphite, whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Parameters affecting retention times and resolution of the separator columns, such as eluent pH, eluent composition, reductant pH and concentration, and flow rates were optimized. Furthermore......, the stabilities of reductant and luminol solutions were studied. The linear range of the calibration curve for chromium(III) and chromium(VI) was 1-400 mu g l(-1). The detection limit was 0.12 mu g l(-1) for chromium(III) and 0.09 mu g l(-1) for chromium(VI), respectively. The precision at the 20 mu g...

  4. Detergents and bleaches are sources of chromium contact dermatitis in Israel

    DEFF Research Database (Denmark)

    Ingber, A; Gammelgaard, Bente; David, M

    1998-01-01

    Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products......, from 1 to 5 ppm in 16 (32%), and lower than 1 ppm in only 6 (12%). Among the 5 imported products, only 1 had a chromium level below 1 ppm and the other 4 (1 from Germany, 3 from the USA) had high levels. Since a most 90% of the detergents and bleaches examined contained chromium levels higher than 1...

  5. The determination of nanogram amounts of Chromium in urine by x-ray fluorescence spectroscopy

    Science.gov (United States)

    Beyermann, K.; Rose, H.J., Jr.; Christian, R.P.

    1969-01-01

    Nanogram amounts of chromium can be extracted as oxinate into chloform. By treatment of the chloroform layer 3 M hydrochloric acid, oxinates of other elements and excess of reagent are removed, leaving a chloroform solution of the chromium chelate only. This solution is concentrated and transferred to the top of a small brass rod acting as sample holder. The intensity of the X-ray fluorescence of the Cr K?? line is measured with curved crystal optics. Chromium amounts greater than 5 ng can be detected. The application of the procedure to the analysis of the chromium content of urine is demonstrated. ?? 1969.

  6. Hexavalent chromium and its effect on health: possible protective role of garlic (Allium sativum Linn).

    Science.gov (United States)

    Das, Kusal K; Dhundasi, Salim A; Das, Swastika N

    2011-01-01

    Hexavalent chromium or chromium (VI) is a powerful epithelial irritant and a confirmed human carcinogen. This heavy metal is toxic to many plants, aquatic animals, and bacteria. Chromium (VI) which consists of 10%-15% total chromium usage, is principally used for metal plating (H2Cr2O7), as dyes, paint pigments, and leather tanning, etc. Industrial production of chromium (II) and (III) compounds are also available but in small amounts as compared to chromium (VI). Chromium (VI) can act as an oxidant directly on the skin surface or it can be absorbed through the skin, especially if the skin surface is damaged. The prooxidative effects of chromium (VI) inhibit antioxidant enzymes and deplete intracellular glutathione in living systems and act as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agents. In this review, we particularly address the hexavalent chromium-induced generation of reactive oxygen species and increased lipid peroxidation in humans and animals, and the possible role of garlic (Allium sativum Linn) as a protective antioxidant. PMID:22865357

  7. Biosorption and biotransformation of chromium by Serratia sp. isolated from tannery effluent.

    Science.gov (United States)

    Srivastava, Shaili; Thakur, Indu Shekhar

    2012-01-01

    A bacterium isolated from soil and sediment ofa leather tanning mill's effluent was identified as Serratia sp. by the analysis of 16S rDNA. Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and transmission electron microscopy (TEM) were used to assess morphological changes and confirm chromium biosorption in Serratia sp. both in a shake-flask culture containing chromium and in a tannery wastewater. The SEMEDX and the elemental analysis of the chromate-containing samples confirmed the binding of chromium with the bacterial biomass. The TEM exhibited chromium accumulation throughout the bacterial cell, with some granular deposits in the cell periphery and in the cytoplasm. X-ray diffraction analysis (XRD) was used to quantify the chromium and to determine the chemical nature of the metal-microbe interaction. The XRD data showed the crystalline character of the precipitates, which consisted of mainly calcium chromium oxide, chromium fluoride phosphate and related organo-Cr(III) complex crystals. The XRD data also revealed a strong involvement of cellular carboxyl and phosphate groups in chromium binding by the bacterial biomass. The results of the study indicated that a combined mechanism of ion-exchange, complexation, croprecipitation and immobilization was involved in the biosorption of chromium by bacterial cells in contaminated environments. PMID:22519094

  8. Chromium recovery from exhausted baths generated in plating processes and its reuse in the tanning industry.

    Science.gov (United States)

    Torras, Josep; Buj, Irene; Rovira, Miquel; de Pablo, Joan

    2012-03-30

    Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution. PMID:22326242

  9. Progress in the chemistry of chromium(V) doping agents used in polarized target materials

    International Nuclear Information System (INIS)

    We wish to report progress in two areas of the chromium (V)-based doping agents: Two commonly used chromium (V) complexes, I and II, have been synthesized in perdeuterated form (i.e., all hydrogens replaced by deuterium). They are sodium bis(2-ethyl-2-deuteroxy-butyrato)oxochromate(V)monodeuterate, IV, (acronym EDBA-Cr(V)), and sodium bis(2-deuteroxy-2-methylpropionato)oxochromate(V), III, (acronym DMPA-Cr(V)). A synthetic route leading to the preparation of stable, chromium(III)-free solutions of chromium(V) in diols (1,2-ethanediol/ethylene glycol/and 1,2-propanediol/propylene glycol/) has been outlined

  10. ANTIBIOTIC RESISTANCE AND CHROMIUM REDUCTION PATTERN AMONG ACTINOMYCETES

    Directory of Open Access Journals (Sweden)

    Preeti Jain

    2012-01-01

    Full Text Available Actinomycetes, one of the most important groups of microbes, exhibit many interesting activities such as degradation and transformation of organic and metal substrates together with production of antibiotics. With these bioactivities, actinomycetes would play an important role in the webs of the marine environment. The present study was designed to evaluate the antibiotic resistance pattern, antibiotic producing potential and chromium resistance as well as chromium reduction potential of a range of actinomycetes isolated from marine environments. Actinomycetes were isolated from marine sediment samples obtained from St. Martin’s Island in Bangladesh. Antibiotic resistance among the selected isolates was studied against 10 different antibiotics by disc diffusion method and antibiotic producing potential was assessed by the perpendicular streak method. The isolates were screened for resistance towards heavy metal Cr(VI on culture plates supplemented with Cr(VI at concentrations ranging from 1-5 mM of Cr(VI. Highly resistant isolates were subjected to screening for Cr(VI reduction activity, which was estimated using the Cr(VI specific colorimetric reagent 1, 5-diphenylcarbazide. Out of the total 30 different selected isolates, 25 (83.33% showed resistance against more than three antibiotics and 6 (20% showed resistance to more than six antibiotics. Ninety three percent of the isolates showed MAR index greater than 0.2 and tolerance to Cr(VI at 1mM of initial Cr(VI. None of the isolates displayed antimicrobial activity against the organisms tested. Among the isolates tested for chromate reduction, two were most efficient showing complete reduction of 1mM Cr(VI within 24 h. These two isolates (SM-11, SM-20 were capable of reducing chromate even at high initial Cr(VI concentrations. Remarkably, the isolate SM-11 was found to reduce 82.67%, 44.34% of Cr(VI at 2.5mM, 5mM of initial Cr(VI concentrations respectively, within 72h of incubation. The

  11. Effect of Chromium Supplementation on Glucose Metabolism and Lipids: A Systematic Review with Meta-Analysis of Randomized Controlled Trials

    Science.gov (United States)

    Objective. A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels. Research Design and Methods. Literature search conducted in MEDLINE and Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium ...

  12. High temperature oxidation of iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, Lars

    2003-06-15

    The high temperature oxidation of the ferritic alloy Fe78Cr22 has been investigated in the present work. The effect of small alloying additions of cerium and/or silicon was also investigated. The alloys were oxidized at 973, 1173 and 1373 K in either air or a hydrogen/argon mixture. The various reaction atmospheres contained between 0.02 and 50% water vapour. The oxide scales formed on the various alloys at 973 K consisted of thin chromia layers. The oxide scales grown on the alloys at 1173 K also consisted of a chromia layer. The microstructure of the chromia scales was found to depend on the reaction atmosphere. The chromia scales grown in hydrogen/argon atmospheres formed oxide whiskers and oxide ridges at the surface of the scales, while the chromia scales grown in air formed larger oxide grains near the surface. This difference in oxide microstructure was due to the vaporization of chromium species from the chromia scales grown in air. Two different growth mechanisms are proposed for the growth of oxide whiskers. The growth rate of the chromia scales was independent of the oxygen activity. This is explained by a growth mechanism of the chromia scales, where the growth is governed by the diffusion of interstitial chromium. The addition of silicon to the iron-chromium alloy resulted in the formation of silica particles beneath the chromia scale. The presence of silicon in the alloy was found to decrease the growth rate of the chromia scale. This is explained by a blocking mechanism, where the silica particles beneath the chromia scale partly block the outwards diffusion of chromium from the alloy to the chromia scale. The addition of cerium to the iron-chromium alloy improved the adhesion of the chromia scale to the alloy and decreased the growth rate of chromia. It was observed that the minimum concentration of cerium in the alloy should be 0.3 at.% in order to observe an effect of the cerium addition. The effect of cerium is explained by the &apos

  13. Skin permeation and cutaneous hypersensitivity as a basis for making risk assessments of chromium as a soil contaminant.

    OpenAIRE

    Bagdon, R E; Hazen, R E

    1991-01-01

    A literature review of experimental and human exposure studies of skin permeation and cutaneous hypersensitivity reactions evoked by chromium was carried out to provide a basis for making a risk assessment of chromium as a soil contaminant. In vitro and in vivo studies demonstrated that 1 to 4% of the applied dose of hexavalent and trivalent chromium to guinea pig skin penetrated skin within 5 to 24 hr after application. Ultrastructural investigations showed that hexavalent chromium localized...

  14. BIOSORPTION OF CHROMIUM (VI) FROM INDUSTRIAL EFFLUENT BY WILD ANDMUTANT TYPE STRAIN OF SACCHAROMYCES CEREVISIAE AND ITS IMMOBILIZED FORM

    OpenAIRE

    K Selvam, K Arungandhi, B Vishnupriya, T Shanmuga priya and M Yamuna

    2013-01-01

    Biosorption of chromium was studied by wild type Saccharomyces cerevisiae strain, mutant strain, immobilized-wild type and mutant strain. Chromium absorption pattern was observed in all experimental conditions. Hexavalent chromium (VI) was analyzed by diphenyl carbazide method, by oxidizing the trivalent chromium (III). The percentage efficiency of wild type S. cerevisiae and its mutant strain, immobilized-wild type and mutant strain were 94.8%, 98.7%, 97.4% and 100% respectively. S. cerevisi...

  15. O impacto do crômio nos sistemas biológicos The impact of chromium on biological systems

    OpenAIRE

    Alba Denise de Queiroz Ferreira

    2002-01-01

    The impact of biological chromium's activity may be beneficial or not. This review presents the most relevant chemical aspects of these "two faces" of chromium by covering first, the efforts toward a clearer understanding of the carcinogenic properties of chromium compounds. The biomimetic chemistry of Cr(V) complexes illustrates the interactions of the intermediates formed by Cr(VI) reduction with DNA or oligonucleotides. The importance of trivalent chromium as an essential element is also e...

  16. [Effect of food diet supplements with chromium on the clinical and metabolic parameters in type 2 diabetic patients].

    Science.gov (United States)

    Sharafetdinov, Kh Kh; Meshcheriakova, V A; Plotnikova, O A; Mazo, V K; Gmoshinskiĭ, I V; Nechaeva, S V

    2004-01-01

    It was investigated the influence of food diet supplements with chromium on dynamic of glycaemia, lipid profile, blood pressure and weight in type 2 diabetic patients. Traditional hypocaloric diet was supplemented with chromium-spirulina (50 mcg chromium per day). The results investigations indicated that a chromium-enriched diet has beneficial effects on basal and postprandial glycaemia, the content of cholesterol and triglycerides in serum in compared with a traditional hypocaloric diet. PMID:15754482

  17. Thermal stabilization of chromium(VI) in kaolin.

    Science.gov (United States)

    Wei, Yu-Ling; Chiu, Shu-Yuan; Tsai, Hsien-Neng; Yang, Yaw-Wen; Lee, Jyh-Fu

    2002-11-01

    Reduction of Cr(VI) by heating may be a useful detoxification mechanism for thermal immobilization. Using X-ray absorption spectroscopy, the change of speciation of chromium in 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin further heated at 500, 900, or 1100 degrees C was studied. The 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin sample was prepared by mixing 1.5 L of 0.257 M CrO3 solution (pH 0.71) with 0.5 kg of kaolin powder for 48 h, and then the slurry was heated (dried) at 105 degrees C until a constant weight was reached. The toxicity characteristic leaching procedure method was used to determine the percentage of leached chromium from all heated samples. In all 500-900 degrees C heated Cr(VI)-sorbed kaolin samples, Cr2O3 transformed from the hydrated Cr(VI) by a 4-h heat application was identified by the X-ray absorption near edge structure and extended X-ray absorption fine structure (EXAFS) spectroscopy as the key species that is leaching-resistant due to its low solubility. For the 1100 degrees C heated Cr(VI)-sorbed kaolin sample, the Fourier transform of its EXAFS spectrum indicates that the intensity of the peaks at 2.45 (Cr-Cr shell of Cr2O3) and 5.00 A (Cr-Cr and Cr-O shells of Cr2O3) without phase shift correction is either relatively smaller or disappearing, compared with that of the 500-900 degrees C heated Cr(VI)-sorbed kaolin samples. It is suggested that chromium octahedra were bridged to silica tetrahedra and incorporated in minerals formed at 1100 degrees C, such as mullite or sillimanite, since these phases were detected by XRD. Cr of this form is not easily leached. PMID:12433175

  18. Evaluation of chromium concentration in cattle feces using different acid digestion and spectrophotometric quantification techniques

    Directory of Open Access Journals (Sweden)

    N.K.P. Souza

    2013-10-01

    Full Text Available The objective of this work was to evaluate combinations between acid digestion techniques and spectrophotometric quantification to measure chromium concentration in cattle feces. Digestion techniques were evaluated based on the use of nitric and perchloric acids, sulfuric and perchloric acids, and phosphoric acid. The chromium quantification in the solutions was performed by colorimetry and by atomic absorption spectrophotometry (AAS. When AAS was used, the addition of calcium chloride to the solutions as a releasing agent was also evaluated. Several standard samples containing known chromium contents were produced (0, 2, 4, 6, 8 and 10g of chromium per kg of feces using cattle feces obtained from three different animals to evaluate the accuracy of the different combinations of techniques. The accuracy was evaluated by adjusting a simple linear regression model of the estimated values on the actual values of chromium content in the standard samples. Regardless of the digestion technique, the chromium content estimates in the standard samples obtained by colorimetry were not accurate (P0.05. The use of the digestion technique in phosphoric acid provided incomplete recovery of the fecal chromium (P0.05 fecal chromium contents.

  19. TOXICITY OF TRIVALENT CHROMIUM TO EARLY LIFE STAGES OF STEELHEAD TROUT

    Science.gov (United States)

    Acute and early life stage toxicity tests were conducted with trivalent chromium and steelhead trout (Salmo gairdneri). A 96-h LC50 of 4,400 micrograms/l chromium was obtained with two-month-old juvenile fish. Early life stage exposure from newly fertilized eggs to 30-d post-swim...

  20. Chromium trace determination in inorganic, organic and aqueous samples with isotope dilution mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, A.; Heumann, K.G.

    1988-06-01

    It is shown that chromium traces in different inorganic, organic and aqueous samples can be determined over a wide concentration range with isotope dilution mass spectrometry. Electrolytic or chromatographic isolation steps are added to a system of sample preparation units for oligo-element determinations to analyse chromium besides other heavy metals. The isotope ratio /sup 52/Cr//sup 53/Cr is measured in a thermal quadrupole mass spectrometer using a single-filament ion source with additions of silica gel and boric acid. In water samples, which contain humic substances, chromium concentrations of a few ng/g and less can be determined with relative standard deviations of about 1% and better. A differentiation is possible into the total chromium content and into chromium species which carry out isotope exchange reactions and those which are inert for an isotope exchange reaction. The chromium concentrations of four standard reference materials (two plants BCR 60 and 61, one tissue BCR 278, one sewage sludge BCR 144), which are not certified for chromium, are determined to be 29.4 ..mu..g/g, 534 ..mu..g/g, 0.78 ..mu..g/g, and 466.1 ..mu..g/g, respectively. In three different sediments total chromium concentrations between 100 ..mu..g/g and 180 ..mu..g/g are analysed with relative standard deviations of 0.6%-1.2%.