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Sample records for molybdenum phosphite complexes

  1. The Synthesis of Glycosyl Phosphite-Pt(Ⅱ) Complexes

    Institute of Scientific and Technical Information of China (English)

    Ling Hua CAO; Hong Yun GAO; Chuan Jian ZHOU; Yu Ting LIU

    2004-01-01

    Ethylene glycol phosphorochloridite 1 or catechol phosphorochloridite 2 reacted with isopropylidene derivatives of D-glucose, D-galactose, D-mannose and D-fructose, a series of glycosyl phosphites were obtained. These glycosyl phosphites form optically active complexes with simple Pt (Ⅱ) salts. Pt (Ⅱ) is coordinated to the phosphorus atom, most of the metal complexes are quite stable.

  2. Synthesis and Reactivity of Ruthenium Phosphite Indenylidene Complexes

    OpenAIRE

    Bantreil, Xavier; Poater, Albert; Urbina-Blanco, César A; Bidal, Yannick D.; Falivene, Laura; Randall, Rebecca A. M.; Cavallo, Luigi; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.

    2012-01-01

    The synthesis of the four olefin metathesis precatalysts Caz-1a-d, featuring the NHC ligand N,N'-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) and four different phosphites (P((OPr)-Pr-i)(3), P(OPh)(3), P(OEt)(3), and P(OMe)(3)), is reported. The complexes are readily synthesized from commercially available [RuCl2(3-phenylinden-1-ylidene)-(pyridine)(SIMes)] (Ind-III) in yields of up to 88%. These complexes adopt an unusual cis configuration between the phosphite and the NHC ligands. ...

  3. Hydroformylation of olefins catalyzed by chiral phosphite- Rh(I) complexes

    Institute of Scientific and Technical Information of China (English)

    YAN Ming; LI Xingshu; CHAN Albert Sunchi

    2003-01-01

    A series of chiral phosphite ligands based on chiral binaphthol have been designed and synthesized. Their Rhodium(I) complexes were found to be efficient catalysts for the asymmetric hydroformylation of styrene and vinyl acetate and showed excellent catalytic activities and chemos- electivities as well as good regioselectivities (branched aldehyde/linear aldehyde). The enantioselectivities up to 37.0% ee and 38.1% ee were achieved in the hydroformylation of styrene and vinyl acetate respectively. The chiral bidentate phosphite ligands provided better enantioselectivities, however lower regioselectivities than the chiral mono-dentate phosphite ligand.

  4. A Novel Catenarian Cyano(triphenyl phosphite) Copper(Ⅰ) Complex: Synthesis, Crystal Structure, Thermal, Voltammetric and Spectral Properties

    Institute of Scientific and Technical Information of China (English)

    QIAO,Yuan-Biao; WANG,Ke-Fei; HU,Li-Hong; JIAN,Fang-Fang

    2006-01-01

    Quantitative reaction between copper(Ⅰ) cyanide and triphenyl phosphite forms copper(Ⅰ) complex [(P(OPh)3)4Cu4(CN)4] (1). X-Ray crystal structure shows a catenarian polymer of tandem interconnected copper cyanide, with C and N connecting to proximal Cu atoms. The Cu atoms adopt two different conformations: one exhibits linear construction, while the other exhibits distorted tetrahedral geometry through coordinating to two cyano groups and the P donors of triphenyl phosphite molecules. The feature of 1 is the propagation pattern of two- and four-coordination along with the chain. IR and electronic absorption spectra also confirm the established single crystal structure. Thermal analysis indicates that 1 has a high thermal stability. 3-D fluorescence result shows the middle absorption peaks with the maximum excitement and emission wavelength 342 and 350 nm, respectively.Cyclic voltammogram in DMSO, DMF and MeCN gives a midpoint voltage of -0.003, 0.061 and 0.137 V versus SCE, respectively, showing the different solvent virtue on reduction potential.

  5. A solvent extraction study of molybdenum chloride and molybdenum thiocyanate complexes

    Science.gov (United States)

    Greenland, L.P.; Lillie, E.G.

    1974-01-01

    The effect of reducing agents on molybdenum(VI) solutions in hydrochloric acid was studied by a solvent extraction technique to elucidate the composition of the colored molybdenum thiocyanate complex. Neither copper(I) chloride nor ascorbic acid have any effect on the extraction of MoO2Cl2; it is inferred that tin(II) chloride reduces Mo(VI) stepwise to a polynuclear Mo(V)??Mo(VI) complex and then to Mo(V). The colored thiocyanate complex produced by copper(I) and by ascorbic acid differs only slightly in extraction characteristics from the uncolored Mo(VI) complex. It is suggested that the color may be produced by an isomerization reaction of MoO2(SCN)2, and thus that the colored species may be a hexavalent rather than pentavalent molybdenum complex. ?? 1974.

  6. Spectrophotometric determination of molybdenum by extraction of its thiosulphate complex.

    Science.gov (United States)

    Yatirajam, V; Ram, J

    1974-12-01

    A simple and rapid spectrophotometric determination of molybdenum is described. The molybdenum thiosulphate complex is extracted into isoamyl alcohol from 1.0-1.5M hydrochloric acid containing 36-40 mg of Na(2)S(2)O(3).5H(2)O per ml. The absorbance at lambda(max) = 475 nm obeys Beer's law over the range 0-32 microg of Mo per ml of solvent phase. Up to 5 mg/ml of Ti(IV), V(V), Cr(VI), Fe(III), Co(II), Ni(II), U(VI), W(VI), Sb(III), 1 mg/ml of Cu(II), Sn(II), Bi(V) and 10 microg/ml of Pt(IV) and Pd(II) do not interfere. Large amounts of complexing agents interfere. The method has been applied to analysis of synthetic and industrial samples.

  7. Phosphite disrupts the acclimation of Saccharomyces cerevisiae to phosphate starvation.

    Science.gov (United States)

    McDonald, A E; Niere, J O; Plaxton, W C

    2001-11-01

    The influence of phosphite (H2PO3-) on the response of Saccharomyces cerevisiae to orthophosphate (HPO4(2-); Pi) starvation was assessed. Phosphate-repressible acid phosphatase (rAPase) derepression and cell development were abolished when phosphate-sufficient (+Pi) yeast were subcultured into phosphate-deficient (-Pi) media containing 0.1 mM phosphite. By contrast, treatment with 0.1 mM phosphite exerted no influence on rAPase activity or growth of +Pi cells. 31P NMR spectroscopy revealed that phosphite is assimilated and concentrated by yeast cultured with 0.1 mM phosphite, and that the levels of sugar phosphates, pyrophosphate, and particularly polyphosphate were significantly reduced in the phosphite-treated -Pi cells. Examination of phosphite's effects on two PHO regulon mutants that constitutively express rAPase indicated that (i) a potential target for phosphite's action in -Pi yeast is Pho84 (plasmalemma high-affinity Pi transporter and component of a putative phosphate sensor-complex), and that (ii) an additional mechanism exists to control rAPase expression that is independent of Pho85 (cyclin-dependent protein kinase). Marked accumulation of polyphosphate in the delta pho85 mutant suggested that Pho85 contributes to the control of polyphosphate metabolism. Results are consistent with the hypothesis that phosphite obstructs the signaling pathway by which S. cerevisiae perceives and responds to phosphate deprivation at the molecular level.

  8. Storage and Bioavailability of Molybdenum in Soils Increased by Organic Matter Complexation

    Energy Technology Data Exchange (ETDEWEB)

    Wichard, T.; Mishra, B; Myneni, S; Bellenger, J; Kraepiel, A

    2009-01-01

    The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase1, 2. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching3, 4. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes3. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexes with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.

  9. Photodecomposition of Molybdenum andTungsten Carbonyl Complexes

    Directory of Open Access Journals (Sweden)

    Thamer A. Alwani

    2009-01-01

    Full Text Available The photodecomposition of four different colored organometallic molybdenum and tungsten carbonyl complexes, i.e. [Mo(CO52LA] (complex I, [(Mo(CO3(bipy2LB] (complex II, [(W(CO3(tmen2LB] (complex III and [Mo(CO2LC]2 (complex I V where LA 2-phenyl-1,3-indandionebis(2-methyl anilines, LB 2-phenyl-1,3-indandione bis (4-hydroxy anilines and LCbis (2-hydroxo-benzalydine benzidine ion have been performed at 365 nm in chloroform at 25 °C under oxygen atmosphere. The absorbance spectrum of these complexes has been recorded with the time of irradiation in order to examine the kinetics of photodecomposition. The rate of the photodecomposition process was investigated and the relative values of the rate constants of dissociation (Kd for the first-order reaction are tabulated. The apparent rate constant of photodecomposition was found to be (8.33-11.50 × 10-5 s-1.

  10. Synthesis, structures, and reactivity of the base-stabilized silanone molybdenum complexes.

    Science.gov (United States)

    Muraoka, Takako; Abe, Keisuke; Kimura, Haruhiko; Haga, Youhei; Ueno, Keiji; Sunada, Yusuke

    2014-11-28

    Base-stabilized silanone molybdenum complexes were synthesized by the oxygenation of the M=Si bond in the silyl(silylene)molybdenum complex with 1 eq. of PNO in the presence of Lewis base L. The PNO-coordinated silanone complex (L = PNO) was converted to cis-[Cp*(OC)2Mo{OSiMes2(OSiMe3)}(PMe3)] in the presence of excess PMe3.

  11. Solvent-Dependent Pyranopterin Cyclization in Molybdenum Cofactor Model Complexes.

    Science.gov (United States)

    Williams, Benjamin R; Gisewhite, Douglas; Kalinsky, Anna; Esmail, Alisha; Burgmayer, Sharon J Nieter

    2015-09-08

    The conserved pterin dithiolene ligand that coordinates molybdenum (Mo) in the cofactor (Moco) of mononuclear Mo enzymes can exist in both a tricyclic pyranopterin dithiolene form and as a bicyclic pterin-dithiolene form as observed in protein crystal structures of several bacterial molybdoenzymes. Interconversion between the tricyclic and bicyclic forms via pyran scission and cyclization has been hypothesized to play a role in the catalytic mechanism of Moco. Therefore, understanding the interconversion between the tricyclic and bicyclic forms, a type of ring-chain tautomerism, is an important aspect of study to understand its role in catalysis. In this study, equilibrium constants (K(eq)) as well as enthalpy, entropy, and free energy values are obtained for pyran ring tautomerism exhibited by two Moco model complexes, namely, (Et4N)[Tp*Mo(O)(S2BMOPP)] (1) and (Et4N)[Tp*Mo(O)(S2PEOPP)] (2), as a solvent-dependent equilibrium process. Keq values obtained from (1)H NMR data in seven deuterated solvents show a correlation between solvent polarity and tautomer form, where solvents with higher polarity parameters favor the pyran form.

  12. Reactions of alkyl malonates with molybdenum and tungsten complexes. Syntheses and structure of hydrido-malonato complexes

    Energy Technology Data Exchange (ETDEWEB)

    Minato, Makoto; Kurishima, Susumu; Nagai, Ko-ichiro; Ito, Takashi [Yokohama National Univ. (Japan). Faculty of Engineering; Yamasaki, Mikio

    1994-12-01

    Molybdenum and tungsten hydrido-malonato complexes have been prepared by the photochemical or thermal reactions of [MoH{sub 4}(dppe){sub 2}] or trans-[W(N{sub 2}){sub 2}(dppe){sub 2}] with an excess of alkyl malonates. The structure of the complex is reported, and a possible mechanism is proposed for the reaction. (author).

  13. Adaptive behavior of a redox-active gallium carbenoid in complexes with molybdenum.

    Science.gov (United States)

    Fedushkin, Igor L; Sokolov, Vladimir G; Piskunov, Alexander V; Makarov, Valentine M; Baranov, Eugeny V; Abakumov, Gleb A

    2014-09-11

    A gallium(I) carbenoid derived from redox-active diimine 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in complexes with molybdenum may serve either as a neutral [(dpp-bian)Ga:] or an anionic [(dpp-bian)Ga:](-) two-electron donor depending on the electronic state of the transition metal.

  14. The molybdenum cofactor biosynthesis complex interacts with actin filaments via molybdenum insertase Cnx1 as anchor protein in Arabidopsis thaliana.

    Science.gov (United States)

    Kaufholdt, David; Baillie, Christin-Kirsty; Bikker, Rolf; Burkart, Valentin; Dudek, Christian-Alexander; von Pein, Linn; Rothkegel, Martin; Mendel, Ralf R; Hänsch, Robert

    2016-03-01

    The pterin based molybdenum cofactor (Moco) plays an essential role in almost all organisms. Its biosynthesis is catalysed by six enzymes in a conserved four step reaction pathway. The last three steps are located in the cytoplasm, where a multimeric protein complex is formed to protect the intermediates from degradation. Bimolecular fluorescence complementation was used to test for cytoskeleton association of the Moco biosynthesis enzymes with actin filaments and microtubules using known cytoskeleton associated proteins, thus permitting non-invasive in vivo studies. Coding sequences of binding proteins were cloned via the GATEWAY system. No Moco biosynthesis enzyme showed any interaction with microtubules. However, alone the two domain protein Cnx1 exhibited interaction with actin filaments mediated by both domains with the Cnx1G domain displaying a stronger interaction. Cnx6 showed actin association only if unlabelled Cnx1 was co-expressed in comparable amounts. So Cnx1 is likely to be the anchor protein for the whole biosynthesis complex on actin filaments. A stabilization of the whole Moco biosynthesis complex on the cytoskeleton might be crucial. In addition a micro-compartmentation might either allow a localisation near the mitochondrial ATM3 exporter providing the first Moco intermediate or near one of the three molybdate transporters enabling efficient molybdate incorporation.

  15. Polarographic study of complexing in the molybdenum (6) - mandelic acid - sulphuric acid system

    Energy Technology Data Exchange (ETDEWEB)

    Zaitsev, P.M.; Zaitseva, Z.V.; Zhdanov, S.I.; Nikolaeva, T.D. (Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Okhrany Truda, Moscow (USSR); Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Khimicheskikh Reaktivov i Osobo Chistykh Veshchestv, Moscow (USSR))

    1980-09-01

    The studies of polarographic behaviour of molybdenum (6) in 0.05-2.5 M H/sub 2/SO/sub 4/ solutions, containing mandelic acid (HL), has shown that molybdenum (6) is reduced via two steps in the presence of HL. One electron is transferred in 0.05 M H/sub 2/SO/sub 4/ during the first step and two during the second one; one electron during each step is transferred if Csub(Hsub(2)SOsub(4))>=0.5 M. Such a difference is suggested to be due to the formation of a mixed-ligand complex MoO/sub 2/xHLx(H/sub 2/SO/sub 4/)/sup +/ which is reduced stepwise, one electron participating at each step. The complex formation is slow. The complex formation constant has been calculated to be 30+-2.7.

  16. Ruthenium indenylidene “1st generation” olefin metathesis catalysts containing triisopropyl phosphite

    Directory of Open Access Journals (Sweden)

    Stefano Guidone

    2015-09-01

    Full Text Available The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords “1st generation” cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L-type ligands.

  17. Ruthenium indenylidene "1(st) generation" olefin metathesis catalysts containing triisopropyl phosphite.

    Science.gov (United States)

    Guidone, Stefano; Nahra, Fady; Slawin, Alexandra M Z; Cazin, Catherine S J

    2015-01-01

    The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords "1(st) generation" cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L-type ligands.

  18. Ruthenium indenylidene “1st generation” olefin metathesis catalysts containing triisopropyl phosphite

    Science.gov (United States)

    Guidone, Stefano; Nahra, Fady; Slawin, Alexandra M Z

    2015-01-01

    Summary The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords “1st generation” cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L-type ligands. PMID:26425210

  19. UV/Vis, MCD and EPR Spectra of Mononuclear Manganese and Molybdenum Complexes

    OpenAIRE

    Westphal, Anne

    2012-01-01

    This PhD thesis deals with the spectroscopic characterization of the electronic structures of mononuclear manganese and molybdenum complexes. At this, in addition to UV/Vis absorption spectroscopy, electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopy were applied in this work. Additionally, new procedures for the general analysis of MCD C-term intensities were developed within the scope of this thesis. It is divided into four parts. Following a general p...

  20. Spectroscopic studies of molybdenum complexes as models for nitrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Walker, T.P.

    1981-05-01

    Because biological nitrogen fixation requires Mo, there is an interest in inorganic Mo complexes which mimic the reactions of nitrogen-fixing enzymes. Two such complexes are the dimer Mo/sub 2/O/sub 4/ (cysteine)/sub 2//sup 2 -/ and trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ (dppe = 1,2-bis(diphenylphosphino)ethane). The H/sup 1/ and C/sup 13/ NMR of solutions of Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ are described. It is shown that in aqueous solution the cysteine ligands assume at least three distinct configurations. A step-wise dissociation of the cysteine ligand is proposed to explain the data. The Extended X-ray Absorption Fine Structure (EXAFS) of trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ is described and compared to the EXAFS of MoH/sub 4/(dppe)/sub 2/. The spectra are fitted to amplitude and phase parameters developed at Bell Laboratories. On the basis of this analysis, one can determine (1) that the dinitrogen complex contains nitrogen and the hydride complex does not and (2) the correct Mo-N distance. This is significant because the Mo inn both complexes is coordinated by four P atoms which dominate the EXAFS. A similar sort of interference is present in nitrogenase due to S coordination of the Mo in the enzyme. This model experiment indicates that, given adequate signal to noise ratios, the presence or absence of dinitrogen coordination to Mo in the enzyme may be determined by EXAFS using existing data analysis techniques. A new reaction between Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ and acetylene is described to the extent it is presently understood. A strong EPR signal is observed, suggesting the production of stable Mo(V) monomers. EXAFS studies support this suggestion. The Mo K-edge is described. The edge data suggests Mo(VI) is also produced in the reaction. Ultraviolet spectra suggest that cysteine is released in the course of the reaction.

  1. Faster oxygen atom transfer catalysis with a tungsten dioxo complex than with its molybdenum analog.

    Science.gov (United States)

    Arumuganathan, T; Mayilmurugan, Ramasamy; Volpe, Manuel; Mösch-Zanetti, Nadia C

    2011-08-21

    The synthesis and characterization of a series of molybdenum ([MoO(2)Cl(L(n))]; L(1) (1), L(2) (3)) and tungsten ([WO(2)Cl(L(n))]; L(1) (2), L(2) (4)) dioxo complexes (L(1) = 1-methyl-4-(2-hydroxybenzyl)-1,4-diazepane and L(2) = 1-methyl-4-(2-hydroxy-3,5-di-tert-butylbenzyl)-1,4-diazepane) of tridentate aminomonophenolate ligands HL(1) and HL(2) are reported. The ligands were obtained by reductive amination of 1-methyl-1,4-diazepane with the corresponding aldehyde. Complexes 3 and 4 were obtained by the reaction of [MO(2)Cl(2)(dme)(n)] (M = Mo, n = 0; W, n = 1) with the corresponding ligand in presence of a base, whereas for the preparation of 1 and 2 the ligands were deprotonated by KH prior to the addition to the metal. They were characterized by NMR and IR spectroscopy, by cyclic voltammetry, mass spectrometry, elemental analysis and by single-crystal X-ray diffraction analysis. Solid-state structures of the molybdenum and tungsten cis-dioxo complexes reveal hexa-coordinate metal centers surrounded by two oxo groups, a chloride ligand and by the tridentate monophenolate ligand which coordinates meridionally through its [ONN] donor set. In the series of compounds 1-4, complexes 3 and 4 have been used as catalysts for the oxygen atom transfer reaction between dimethyl sulfoxide (DMSO) and trimethyl phosphine (PMe(3)). Surprisingly, faster oxygen atom transfer (OAT) reactivity has been observed for the tungsten complex [WO(2)Cl(L(2))] (4) in comparison to its molybdenum analog [MoO(2)Cl(L(2))] (3) at room temperature. The kinetic results are discussed and compared in terms of their reactivity. This journal is © The Royal Society of Chemistry 2011

  2. Synthesis and CD Spectra of Chiral Molybdenum-fullerenyl Complexes with Pineno-bipyridine Ligands

    Institute of Scientific and Technical Information of China (English)

    Hui ZHANG; Cai Fei ZHU; Li LI; Wei ZOU; Yong Qing HUANG; Jing Xing GAO

    2004-01-01

    The synthesis and characterization of two chiral fullerene complexes (+) CD430- [Mo(η2-C60)(CO)3(LRR)] 1 and (-)CD430-[Mo(η2-C60)(CO)3(LSS)] 2 were described. The CD spectra of 1 and 2 in the visible range show weak Cotton effects, which are approximately of mirror image, indicating that the appended pineno-groups with opposite chirality in bipyridines can perturb the fullerene chromophores through the molybdenum centers and lead to induced CD effects.

  3. Solid and Solution Structural Studies of Dimeric and Tetrameric Molybdenum(Ⅵ) Malate Complexes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rong-Hua; ZHOU Zhao-Hui; WAN Hui-Lin

    2008-01-01

    Reactions of potassium molybdate with racemic malic acid (H3mal = C4H6O5) result in the isolation of two mesomeric molybdenum malate complexes Ks[(MoO2)2O(R-mal)2][(MoO2)2O(S- mal)2]·4H2O 1 and (Him)2K6[(MoO2)4O3(R-mal)2][(MoO2)4O3(S-mal)2]·8H2O 2. Complex 1 belongs to the monoclinic system, space group C2/c with a = 14.8637(3), b = 6.9544(1), c = 19.6783(5) A, β = 100.081(2)°, V= 2002.70(7)A3, Mr = 1452.88, Z= 2, F(000) = 1416, T= 173 K, Dc = 2.409 g/cm3, μ(MoKa) = 2.167, R = 0.0283 and wR = 0.0733.2 is of triclinic system, space group P1 with a = 8.7707(2), b = 9.3310(3), c = 17.9093(7) A, α = 83.781(3), β = 85.626(2), γ= 84.822(2)°, V = 1447.84(8) A3, Mr = 2160.68, Z = 1, F(000) = 1048, T= 173 K, Dc = 2.478 g/cm3, μ(MoKα) = 2.230, R = 0.0234 and wR = 0.0584.1 is the first isolated dinuclear molybdenum(Ⅵ) malato complex in 1:1 molar ratio. The molybdenum atoms in the two complexes are six-coordinated in an approximately octahedral geometry. Two malates coordinate tridentately with the Mo atom via their α-alkoxy, α-carboxy and α-carboxy groups in 1 and 2. β-Carboxy group in 2 further links with the other two Mo atoms to give a tetrameric unit. The solution 1H and 13C NMR spectra indicate that dimeric malate molybdenum in 1 dissociates partly in solution and exists in an equilibrium with tetrameric species, while 2 is stable and retains its tetrameric structure without any dissociation.

  4. Structure effect of molybdenum (5) complexes on its activity in appearance of catalytic polarographic currents of chlorate- and perchlorate ions

    Energy Technology Data Exchange (ETDEWEB)

    Zajtsev, P.M.; Zhdanov, S.I.; Dergacheva, E.N.; Savchenko, E.N.; Nikolaeva, T.D. (Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Khimicheskikh Reaktivov i Osobo Chistykh Veshchestv, Moscow (USSR))

    1982-08-01

    Polarographic behaviour and reactivity of synthesized molybdenum (5) in reactions, conditioning catalytic currents of ClO/sub 3//sup -/ and ClO/sub 4//sup -/ have been studied. Their comparison with similar characteristics for molybdenum (5) appearing in the process of Mo (6) solution polarography is made. For the purpose a salt of molybdenum (5) in H/sub 2/SO/sub 4/, HCl and HClO/sub 4/ solutions have been synthesized by electrochemical and chemical ways. It has been established that in reactions conditioning catalytic currents of chlorate- and perchlorate-ions the preservation of structure of Mo (6) complex in the Mo (5) complex formed, i.e. processes of Mo (5) complex ageing, plays a very significant role.

  5. Crystal Structure and EPR Spectra of cis-Dioxo-molybdenum(Ⅴ) Complex with o-Aminophenol

    Institute of Scientific and Technical Information of China (English)

    LU,Xiao-Ming(鲁晓明); LU,Jing-Fen(卢景芬); MAO,Xi-An(毛希安)

    2002-01-01

    The paramagnetic cis-dioxo-molybdenum(V) complex,[NH2CH2CH2NH3]3[HNC6H4O)2] was obtained by the reaction of tetra-butyl ammonium β-octamolybdate with oaminophenol and ethylenediamine in the mixed solvent of CH3OH and CH3CN, and characterized by IR,NMR,EPR spectroscopy and X-ray diffraction analysis .The determination of single crystal X-ray analysis revealed octahedral coordination withcis-dioxo o-aminophenol.The EPR spectra of both the complex and flavoenzyme show similarly.Thus it suggests that the complex anion[MovO2(HNC6H49)2]3-and flavoenzyme have related structure feature.

  6. Dielectric properties of betaine phosphite and deuterated betaine phosphite films

    Science.gov (United States)

    Balashova, E. V.; Krichevtsov, B. B.; Zaitseva, N. V.; Pankova, G. A.; Frederiks, I. D.; Lemanov, V. V.

    2011-01-01

    Polycrystalline films of betaine phosphite (BPI) and deuterated BPI have been grown by evaporation on LiNbO3, α-SiO2, α-Al2O3, and NdGaO3 substrates. These films consist of large single-crystal blocks in which the polar axis ( b) lies in the substrate plane. The results of studying the dielectric properties of the films using interdigital electrodes, X-ray diffraction, and block images in a polarized-light microscope in reflection are reported. The film transition into the ferroelectric state at T = T c is accompanied by strong anomalies of the capacitance of the film/interdigital structure/substrate structure. The deuteration of BPI films leads to an increase in their temperature T c: from T c = 200 K for BPI-based structures to T c = 280 K for structures with a high degree of deuteration ( d ˜ 90%).

  7. Synthesis of molybdenum nitrido complexes for triple-bond metathesis of alkynes and nitriles.

    Energy Technology Data Exchange (ETDEWEB)

    Wiedner, E. S.; Gallagher, K. J.; Johnson, M. A.; Kampf, J. W. (Chemical Sciences and Engineering Division); (Univ. of Michigan)

    2011-06-04

    Complexes of the type N {triple_bond} Mo(OR){sub 3} (R = tertiary alkyl, tertiary silyl, bulky aryl) have been synthesized in the search for molybdenum-based nitrile-alkyne cross-metathesis (NACM) catalysts. Protonolysis of known N {triple_bond} Mo(NMe{sub 2}){sub 3} led to the formation of N {triple_bond} Mo(O-2,6-{sup i}Pr{sub 2}C{sub 6}H{sub 3}){sub 3}(NHMe{sub 2}) (12), N {triple_bond} Mo(OSiPh{sub 3}){sub 3}(NHMe{sub 2}) (5-NHMe{sub 2}), and N {triple_bond} Mo(OCPh{sub 2}Me){sub 3}(NHMe{sub 2}) (17-NHMe{sub 2}). The X-ray structure of 12 revealed an NHMe{sub 2} ligand bound cis to the nitrido ligand, while 5-NHMe{sub 2} possessed an NHMe{sub 2} bound trans to the nitride ligand. Consequently, 17-NHMe{sub 2} readily lost its amine ligand to form N {triple_bond} Mo(OCPh{sub 2}Me){sub 3} (17), while 12 and 5-NHMe{sub 2} retained their amine ligands in solution. Starting from bulkier tris-anilide complexes, N {triple_bond} Mo(N[R]Ar){sub 3} (R = isopropyl, tert-butyl; Ar = 3,5-dimethylphenyl) allowed for the formation of base-free complexes N {triple_bond} Mo(OSiPh3)3 (5) and N {triple_bond} Mo(OSiPh{sub 2}tBu){sub 3} (16). Achievement of a NACM cycle requires the nitride complex to react with alkynes to form alkylidyne complexes; therefore the alkyne cross-metathesis (ACM) activity of the complexes was tested. Complex 5 was found to be an efficient catalyst for the ACM of 1-phenyl-1-butyne at room temperature. Complexes 12 and 5-NHMe{sub 2} were also active for ACM at 75 C, while 17-NHMe{sub 2} and 16 did not show ACM activity. Only 5 proved to be active for the NACM of anisonitrile, which is a reactive substrate in NACM catalyzed by tungsten. NACM with 5 required a reaction temperature of 180 C in order to initiate the requisite alkylidyne-to-nitride conversion, with slightly more than two turnovers achieved prior to catalyst deactivation. Known molybdenum nitrido complexes were screened for NACM activity under similar conditions, and only N {triple_bond} Mo

  8. Synthesis of molybdenum nitrido complexes for triple-bond metathesis of alkynes and nitriles.

    Science.gov (United States)

    Wiedner, Eric S; Gallagher, Kimberley J; Johnson, Marc J A; Kampf, Jeff W

    2011-07-04

    Complexes of the type N≡Mo(OR)(3) (R = tertiary alkyl, tertiary silyl, bulky aryl) have been synthesized in the search for molybdenum-based nitrile-alkyne cross-metathesis (NACM) catalysts. Protonolysis of known N≡Mo(NMe(2))(3) led to the formation of N≡Mo(O-2,6-(i)Pr(2)C(6)H(3))(3)(NHMe(2)) (12), N≡Mo(OSiPh(3))(3)(NHMe(2)) (5-NHMe(2)), and N≡Mo(OCPh(2)Me)(3)(NHMe(2)) (17-NHMe(2)). The X-ray structure of 12 revealed an NHMe(2) ligand bound cis to the nitrido ligand, while 5-NHMe(2) possessed an NHMe(2) bound trans to the nitride ligand. Consequently, 17-NHMe(2) readily lost its amine ligand to form N≡Mo(OCPh(2)Me)(3) (17), while 12 and 5-NHMe(2) retained their amine ligands in solution. Starting from bulkier tris-anilide complexes, N≡Mo(N[R]Ar)(3) (R = isopropyl, tert-butyl; Ar = 3,5-dimethylphenyl) allowed for the formation of base-free complexes N≡Mo(OSiPh(3))(3) (5) and N≡Mo(OSiPh(2)(t)Bu)(3) (16). Achievement of a NACM cycle requires the nitride complex to react with alkynes to form alkylidyne complexes; therefore the alkyne cross-metathesis (ACM) activity of the complexes was tested. Complex 5 was found to be an efficient catalyst for the ACM of 1-phenyl-1-butyne at room temperature. Complexes 12 and 5-NHMe(2) were also active for ACM at 75 °C, while 17-NHMe(2) and 16 did not show ACM activity. Only 5 proved to be active for the NACM of anisonitrile, which is a reactive substrate in NACM catalyzed by tungsten. NACM with 5 required a reaction temperature of 180 °C in order to initiate the requisite alkylidyne-to-nitride conversion, with slightly more than two turnovers achieved prior to catalyst deactivation. Known molybdenum nitrido complexes were screened for NACM activity under similar conditions, and only N≡Mo(OSiPh(3))(3)(py) (5-py) displayed any trace of NACM activity. © 2011 American Chemical Society

  9. Phosphite determination in fertilizers after online sequential sample preparation in a flow injection system.

    Science.gov (United States)

    Dametto, Patrícia Roberta; Franzini, Vanessa Pezza; Gomes Neto, José Anchieta

    2007-07-25

    A flow injection spectrophotometric system is proposed for phosphite determination in fertilizers by the molybdenum blue method after the processing of each sample two times on-line without and with an oxidizing step. The flow system was designed to add sulfuric acid or permanganate solutions alternately into the system by simply displacing the injector-commutator from one resting position to another, allowing the determination of phosphate and total phosphate, respectively. The concentration of phosphite is obtained then by difference between the two measurents. The influence of flow rates, sample volume, and dimension of flow line connecting the injector-commutator to the main analytical channel was evaluated. The proposed method was applied to phosphite determination in commercial liquid fertilizers. Results obtained with the proposed FIA system were not statistically different from those obtained by titrimetry at the 95% confidence level. In addition, recoveries within 94 and 100% of spiked fertilizers were found. The relative standard deviation (n = 12) related to the phosphite-converted-phosphate peak alone was phosphite) solution. The sampling rate was calculated as 15 determinations per hour, and the reagent consumption was about 6.3 mg of KMnO4, 200 mg of (NH4)6Mo7O24.4H2O, and 40 mg of ascorbic acid per measurement.

  10. Molecular Assembly and Micellization of Molybdenum(V, IV) Thiolate and Selenolate Complexes with Long Hydrocarbon Chains

    National Research Council Canada - National Science Library

    Okamura, Taka-aki; Taniuchi, Kaku; Ueyama, Norikazu; Nakamura, Akira

    1999-01-01

    Molybdenum(IV, V) thiolate and selenolate complex with four long bundling hydrocarbon chains connected to the amide group, (Ph4P)[MoVO{S-2-CH3(CH2)10CONHC6H4}4] and (NEt4)2[MoIVO{Se-2-CH3(CH2)10CONHC6H4}4] were synthesized...

  11. Anaerobic utilization of phosphite and hypophosphite by Bacillus sp.

    Science.gov (United States)

    Foster, T. L.; Winans, L., Jr.; Helms, S. J. S.

    1978-01-01

    A Bacillus species capable of using phosphite and hypophosphite under anaerobic conditions was isolated from Cape Canaveral soil samples and grown on a glucose-mineral salts medium with phosphate omitted. The optimum hypophosphite concentration was 60 microg/ml, while the optimum phosphite concentration was greater than 1000 microg/ml. P-32-labeled hypophosphite was incorporated into the cell as organic phosphate, and little or no phosphate appeared in the medium when either hypophosphite or phosphite was the phosphorus source. When phosphate was present in the medium, phosphite was not metabolized. When both phosphite and hypophosphite were present, phosphite was used first and then hypophosphite.

  12. 1,2-Bis(imino)acenaphthene complexes of molybdenum and nickel.

    Science.gov (United States)

    Fedushkin, Igor L; Skatova, Alexandra A; Lukoyanov, Anton N; Khvoinova, Nalalie M; Piskunov, Alexander V; Nikipelov, Alexander S; Fukin, Georgy K; Lysenko, Konstantin A; Irran, Elisabeth; Schumann, Herbert

    2009-06-28

    Molybdenum hexacarbonyl reacts with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (, dpp-BIAN) and 1,2-bis[(trimethylsilyl)imino]acenaphthene (, tms-BIAN) in toluene to produce (dpp-BIAN)Mo(CO)(4) () and (tms-BIAN)Mo(CO)(4) (), respectively. The reaction of [CpNi(CO)](2) with yields (dpp-BIAN)NiCp (). Metathesis between Li(2)(tms-BIAN) and NiCl(2)(dppe) affords the Ni(0) complex (tms-BIAN)Ni(dppe) (). The diamagnetic compounds , and have been characterized by (1)H, (29)Si and (31)P NMR spectroscopy, IR spectroscopy and elemental analysis. The ESR spectrum of the paramagnetic compound indicates the presence of Ni(i) coordinated by Cp and a neutral dpp-BIAN ligand. The molecular structures of have been determined by single-crystal X-ray analysis.

  13. P450BM3 fused to phosphite dehydrogenase allows phosphite-driven selective oxidations

    NARCIS (Netherlands)

    Beyer, Nina; Kulig, Justyna K; Bartsch, Anette; Hayes, Martin A; Janssen, Dick B; Fraaije, Marco W

    2016-01-01

    To facilitate the wider application of the NADPH-dependent P450BM3, we fused the monooxygenase with a phosphite dehydrogenase (PTDH). The resulting monooxygenase-dehydrogenase fusion enzyme acts as a self-sufficient bifunctional catalyst, accepting phosphite as a cheap electron donor for the regener

  14. Structural and functional models in molybdenum and tungsten bioinorganic chemistry: description of selected model complexes, present scenario and possible future scopes.

    Science.gov (United States)

    Majumdar, Amit

    2014-06-28

    A brief description about some selected model complexes in molybdenum and tungsten bioinorganic chemistry is provided. The synthetic strategies involved and their limitations are discussed. Current status of molybdenum and tungsten bioinorganic modeling chemistry is presented briefly and synthetic problems associated therein are analyzed. Possible future directions which may expand the scope of modeling chemistry are suggested.

  15. Dielectric properties of betaine phosphite and deuterated betaine phosphite films

    Energy Technology Data Exchange (ETDEWEB)

    Balashova, E. V., E-mail: balashova@mail.ioffe.ru; Krichevtsov, B. B.; Zaitseva, N. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Pankova, G. A. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Frederiks, I. D.; Lemanov, V. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2011-01-15

    Polycrystalline films of betaine phosphite (BPI) and deuterated BPI have been grown by evaporation on LiNbO{sub 3}, {alpha}-SiO{sub 2}, {alpha}-Al{sub 2}O{sub 3}, and NdGaO{sub 3} substrates. These films consist of large single-crystal blocks in which the polar axis (b) lies in the substrate plane. The results of studying the dielectric properties of the films using interdigital electrodes, X-ray diffraction, and block images in a polarized-light microscope in reflection are reported. The film transition into the ferroelectric state at T = T{sub c} is accompanied by strong anomalies of the capacitance of the film/interdigital structure/substrate structure. The deuteration of BPI films leads to an increase in their temperature T{sub c}: from T{sub c} = 200 K for BPI-based structures to T{sub c} = 280 K for structures with a high degree of deuteration (d {approx} 90%).

  16. DFT calculations of magnetic parameters for molybdenum complexes and hydroxymethyl intermediates trapped on silica surface

    Science.gov (United States)

    Sojka, Zbigniew; Pietrzyk, Piotr

    2006-03-01

    Density functional theory (DFT) calculations of EPR parameters and their structure sensitivity for selected surface paramagnetic species involved in oxidative dehydrogenation of methanol over silica grafted molybdenum catalyst were investigated. Two surface complexes, Mo 4 c/SiO 2 and {O -sbnd Mo 4 c}/SiO 2, as well as rad CH 2OH radical trapped on the SiO 2 matrix were taken as the examples. The spin-restricted zeroth order regular approximation (ZORA) implemented in the Amsterdam Density Functional suite was used to calculate the electronic g tensor for those species. The predicted values were in satisfactory agreement with experimental EPR results. Five different coordination modes of the rad CH 2OH radical on the silica surface were considered and the isotropic 13C, 17O, and 1H hyperfine coupling constants (HFCC) of the resultant surface complexes were calculated. Structure sensitivity of the HFCC values was discussed in terms of the angular deformations caused by hydrogen bonding with the silica surface.

  17. Sulfide and sulfoxide oxidations by mono- and diperoxo complexes of molybdenum. A density functional study.

    Science.gov (United States)

    Sensato, Fabrício R; Custodio, Rogério; Longo, E; Safont, Vicent S; Andres, Juan

    2003-07-25

    The molecular mechanism for the oxidation of sulfides to sulfoxides and subsequent oxidation to sulfones by diperoxo, MoO(O(2))(2)(OPH(3)) (I), and monoperoxo, MoO(2)(O(2))(OPH(3)) (II), complexes of molybdenum was studied using density functional calculations at the b3lyp level and the transition state theory. Complexes I and II were both found to be active species. Sulfide oxidation by I or II shows similar activation free energy values of 18.5 and 20.9 kcal/mol, respectively, whereas sulfoxides are oxidized by I (deltaG = 20.6 kcal/mol) rather than by II (deltaG = 30.3 kcal/mol). Calculated kinetic and thermodynamic parameters account for the spontaneous overoxidation of sulfides to sulfones as has been experimentally observed. The charge decomposition analysis (CDA) of the calculated transition structures of sulfide and sulfoxide oxidations revealed that I and II are stronger electrophilic oxidants toward sulfides than they are toward sulfoxides.

  18. Molybdenum Trihydride Complexes: Computational Model of Oxidatively Induced Reductive Elimination of Dihydrogen.

    Science.gov (United States)

    Szatkowski, Lukasz; Hall, Michael B

    2017-08-21

    Recent experimental work shows that the 18-electron molybdenum complexes (1,2,4-C5H2tBu3)Mo(PMe3)2H3 (Cp(tBu)MoH3) and (C5HiPr4)Mo(PMe3)2H3 (Cp(iPr)MoH3) undergo oxidatively induced reductive elimination of dihydrogen (H2), slowly forming the 15-electron monohydride species in tetrahydrofuran and acetonitrile. The 17-electron [Cp(tBu)MoH3](+) derivative was stable enough to be characterized by X-ray diffraction, while [Cp(iPr)MoH3](+) was not. Density functional theory calculations of the H2 elimination pathways for both complexes in the gas phase and in a continuum solvent model indicate that H2 elimination from [Cp(iPr)MoH3](+) has a lower barrier than that from [Cp(tBu)MoH3](+). Further, a specific solvent association, which is stronger for [Cp(tBu)MoH3](+) than for [Cp(iPr)MoH3](+), contributes to the stability of the former. In agreement with the experimental observations, the calculations predict that [Cp(tBu)MoH3](+) would be in a quartet state at room temperature and a doublet state at 4.2 K, while [Cp(iPr)MoH3](+) is in a doublet state even at room temperature.

  19. Cloud Points of Water—soluble Polyether Phosphites and Their Application in the Biphasic Hydroformylation of Higher Olefins

    Institute of Scientific and Technical Information of China (English)

    LIU,Xiao-Zhong; WANG,Yan-Hua; KONG,Fan-Zhi; JIN,Zi-Lin

    2003-01-01

    Wate-soluble polyether phosphites alkyl polyethylene glycol ophenylene phosphite(APGPPS)were alcoholysis of phosphorus chloride with plyoxyethylene alkyl ether.With appropriate HLB(hydrophile-lypophile balance),the phosphites possess clear cloud points below 100℃,Addition of some inorganic salts decreases cloud points of the phosphites.When the phosphiites have long polyether chain binding to short-chain alkyl group,their cloud points could be extrapolated from figure of dependece of cloud points on addition of inorganic salts.Utilizing octylpolyglycol-phenylene-phosphite(OPGPP)(APGPP,R:Octyl)/Rh complex formed in situ as catalyst,over 90% conversion of 1-decene was obtained ,avoiding the limitation of water insolubility of substrates.Preliminary results indicated that micellar catalysis and thermoregulated phase-transfer catalysis(TRPTC)coexist in the reaction system.Below cloud point,micellar catalysis induced by plyether phosphites may be existed.When temperature is increased to above cloud point of the phosphies,this reaction works mainly in TRPTC.The catalysts could be easily spearated by simple decantation,but followed by considerable loss in activity after three successive reaction runs.Preliminary results indicated hydrolysis of OPGPP happened during the reaction.which may explain for the bad loss in activity.The catalyst was reused up to seven times with-out clear decrease in activity when OPGPP/Rh ratio was increased to 50.

  20. First insights on the molybdenum-copper Bled M'Dena complex (Eglab massif, Algeria)

    Science.gov (United States)

    Lagraa, Karima; Salvi, Stefano; Béziat, Didier; Debat, Pierre; Kolli, Omar

    2017-03-01

    Molybdenum-Copper showings in the Eglab massif (eastern part of the Reguibat rise of Algeria), are found in quartz-monzodiorite and granodiorite of the Bled M'Dena complex, a Paleoproterozoic circular structure of ∼5 km in diameter, comprising volcanic and intrusive suites. The latter consist of quartz-diorite, quartz-monzodiorite and granodiorite with a metaluminous normative composition. They display an "adakitic character" with moderate light rare-earth element (LREE) enrichment, minor Eu anomalies, high Sr/Y ratio and low Yb concentration, suggestive of a hydrous, arc magma of volcanic-arc affinity. The mineralization occurs mostly in quartz + molybdenite + chalcopyrite stockwork veins marked by widespread propylitic alteration along the selvages. Molybdenite and chalcopyrite are commonly associated with calcite, which precipitated at relatively late stages of the hydrothermal alteration. Fluid inclusions related to the mineralization stage, range from aqueous to aqueous-carbonic to solid bearing. The latter inclusions have the highest homogenization temperature (up to ∼400 °C), are salt saturated, and commonly contain molybdenite and/or chalcopyrite crystals. The petrology and geochemistry of the host rocks, the style of the hydrothermal alteration, the ore mineral associations, and the characteristics of the fluid inclusions, are all coherent in indicating that the Bled M'Dena represents a Paleoproterozoic porphyry style Mo mineralization, which is far unreported in the African continent.

  1. Dioxobridged complexes of molybdenum (IV) and tungsten (IV) with N-alkylphenothiazines and their interactions with L-cysteine and L-histidine

    Indian Academy of Sciences (India)

    B Keshavan; Kempe Gowda

    2001-06-01

    Six new dioxobridged complexes of molybdenum (IV) and tungsten (IV) with N-alkylphenothiazines having the general formula M2O4(L)2(H2O)2 [where M = molybdenum or tungsten and L = N-alkylphenothiazines] have been synthesised. The complexes have been characterised on the basis of analytical, molar conductance, magnetic susceptibility, spectral data, TGA and DTA. The low magnetic moments for the complexes are due to spin-spin interaction or metal-metal bonding. The interactions of these complexes with some biologically important amino acids have been studied.

  2. P450BM3 fused to phosphite dehydrogenase allows phosphite-driven selective oxidations.

    Science.gov (United States)

    Beyer, Nina; Kulig, Justyna K; Bartsch, Anette; Hayes, Martin A; Janssen, Dick B; Fraaije, Marco W

    2017-03-01

    To facilitate the wider application of the NADPH-dependent P450BM3, we fused the monooxygenase with a phosphite dehydrogenase (PTDH). The resulting monooxygenase-dehydrogenase fusion enzyme acts as a self-sufficient bifunctional catalyst, accepting phosphite as a cheap electron donor for the regeneration of NADPH.The well-expressed fusion enzyme was purified and analyzed in comparison to the parent enzymes. Using lauric acid as substrate for P450BM3, it was found that the fusion enzyme had similar substrate affinity and hydroxylation selectivity while it displayed a significantly higher activity than the non-fused monooxygenase. Phosphite-driven conversions of lauric acid at restricted NADPH concentrations confirmed multiple turnovers of the cofactor. Interestingly, both the fusion enzyme and the native P450BM3 displayed enzyme concentration dependent activity and the fused enzyme reached optimal activity at a lower enzyme concentration. This suggests that the fusion enzyme has an improved tendency to form functional oligomers.To explore the constructed phosphite-driven P450BM3 as a biocatalyst, conversions of the drug compounds omeprazole and rosiglitazone were performed. PTDH-P450BM3 driven by phosphite was found to be more efficient in terms of total turnover when compared with P450BM3 driven by NADPH. The results suggest that PTDH-P450BM3 is an attractive system for use in biocatalytic and drug metabolism studies.

  3. Molybdenum isotope fractionation during complexation with organic matter in the Critical Zone

    Science.gov (United States)

    King, E. K.; Pett-Ridge, J. C.; Perakis, S. S.

    2016-12-01

    Molybdenum (Mo) is a micronutrient and a redox sensitive trace metal that also forms strong complexes with organic matter (OM). The fractionation of Mo in sediments associated with adsorption onto both iron (Fe) and manganese (Mn) (oxyhydr)oxides under oxic conditions and sulfide phases under euxinic conditions has been used to constrain redox conditions in the ocean. Additionally, Mo isotope dynamics in terrestrial systems can shed light on the pedogenic mechanisms driving the riverine Mo isotopic composition and how atmospheric inputs alter the trace metal budget and isotopic composition of soils. As a result of these studies, it has been hypothesized that multiple mechanisms are responsible for fractionating Mo isotopes. In particular, Mo fractionation during adsorption onto OM is unknown, despite the fact this mechanism is 3x to more than 20x greater than adsorption onto Fe- and Mn- (oxyhydr)oxides across a range of soil types from Oregon, Iceland, and Hawaii1-3 (Marks et al., 2015; Siebert et al., 2015; King et al., 2016). In this study, we measured Mo adsorption and isotopic fractionation onto insolubilized humic acid (IHA), a proxy for OM, as a function of both adsorption time (2-170 h) and pH (2-7). Preliminary results suggest that for the time series experiment, Mo adsorption onto IHA increased from 35% to 64% and a plateau was reached after 24 hours. The average Mo isotope fractionation between the solution and the IHA was Δ98Mosolution-IHA = 1.8 ± 0.3‰. For the pH series experiment, the average Mo isotope fractionation was Δ98Mosolution-IHA = 2.0 ± 0.2‰. Next, we compared the Mo isotopic composition of foliage, O-horizon, and surface soil from 12 sites in the Oregon Coast Range to better understand the impact of OM on Mo isotope dynamics in natural samples. The potential isotopic offset between dissolved and adsorbed Mo onto OM is of the same order of magnitude and direction as fractionation onto Fe- and Mn- (oxyhydr)oxides such as ferrihydrite

  4. Molybdenum (VI Imido Complexes Derived from Chelating Phenols: Synthesis, Characterization and ɛ-Caprolactone ROP Capability

    Directory of Open Access Journals (Sweden)

    Yahya Al-Khafaji

    2015-11-01

    Full Text Available Reaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu2C6H2OH]2 (R = Me L1MeH2, Ph L1PhH2 with the bis(imido molybdenum(VI tert-butoxides [Mo(NR1(NR2(Ot-Bu2] (R1 = R2 = 2,6-C6H3-i-Pr2; R1 = t-Bu, R2 = C6F5 afforded, following the successive removal of tert-butanol, the complexes [Mo(NC6H3i-Pr2-2,62L1Me] (1, [Mo(NC6H3i-Pr2-2,62L1Ph] (2 and [Mo(Nt-Bu(μ-NC6F5(L1Me]2 (3. Similar use of the tri-phenol 2,6-bis(3,5-di-tert -butyl-2-hydroxybenzyl-4-methylphenol (L2H3 with [Mo(NC6H3i-Pr2-2,62(Ot-Bu2] afforded the oxo-bridged product [Mo(NC6H3i-Pr2-2,6(NCMe(μ-OL2H]2 (4, whilst use of the tetra-phenols α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl-p- or -m-xylene L3pH4/L3mH4 led to {[Mo(NC6H3i-Pr2-2,62]2(μ-L3p} (5 or {[Mo(NC6H3i-Pr2-2,62]2(μ-L3m} (6, respectively. Similar use of [Mo(NC6F52(Ot-Bu2] with L3pH4 afforded, after work-up, the complex {[Mo(NC6F5(Ot-Bu2]2(μ-L3p}·6MeCN (7·6MeCN. Molecular structures of 1, 2·CH2Cl2, 3, 4·6MeCN, 6·2C6H14, and 7·6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP ε-caprolactone; for comparative studies the precursor complex [Mo(NC6H3i-Pr2-2,62Cl2(DME] (DME = 1,2-dimethoxyethane has also been screened. Results revealed that good activity is only achievable at temperatures of ≥100 °C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (Mn were much lower than calculated values.

  5. Inorganic polarography in organic solvents-II: polarographic examination of the molybdenum(V) thiocyanate complex in diethyl ether.

    Science.gov (United States)

    Afghan, B K; Dagnall, R M

    1967-02-01

    A procedure involving the solvent extraction of molybdenum(V) thiocyanate into diethyl ether followed by a direct polarographic examination of the organic phase offers a selective method for the determination of molybdenum down to 0.5 ppm. Only molybdenum, amongst 21 elements examined, is observed to give a reduction wave under the recommended conditions. The method is evaluated with respect to various experimental factors and is applied to the determination of molybdenum in mild and alloy steels.

  6. Hydroformylation of Oleyl Alcohol Catalyzed by Rh-OPGPP Complex

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Polyether-tailored phosphite modified rhodium complex formed in situ was highly active in the hydroformylation of oleyl alcohol in nonaqueous phosphite/heptane system where the phosphite acted both as the ligand and the second phase. This catalyst was easily separated by simple decantation and can be used for five times with only a slight decrease in activity.

  7. Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Beitollahi, Hadi, E-mail: h.beitollahi@yahoo.com [Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Sheikhshoaie, Iran [Department of Chemistry, Faculty of Science, Shahid Bahonar University of Kerman, Kerman 76175-133 (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. > This electrode reduced the oxidation potential of isoproterenol by about 175 mV. > It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 {mu}M, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

  8. Solid-Phase Parallel Synthesis of Phosphite Ligands

    NARCIS (Netherlands)

    Swennenhuis, Bert H.G.; Chen, Ruifang; Leeuwen, Piet W.N.M. van; Vries, Johannes G. de; Kamer, Paul C.J.

    2008-01-01

    Various routes for the synthesis of polymer-bound phosphites and phosphoramidites have been investigated. In the presence of a suitable activator the supported phosphoramidites react cleanly with alcohols to give the corresponding monodentate phosphite ligands in solution. We have applied this novel

  9. Solvent Effects on Complexation of Molybdenum(VI) with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

    Institute of Scientific and Technical Information of China (English)

    MOHAMMADI Behrouz; MOHAMMADI Jalal

    2007-01-01

    By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H++Mo(VI)+nitrilotriacetic acid and H++nitrilotriacetic acid have been determined in aqueous solutions plex was determined by the continuous variation method. It was shown that molybdenum(VI) forms a mononuclear 1 : 1 complex with nitrilotriacetic acid of the type MoO3L-3 at -1g[H+]=5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Linear relationships were observed when 1g Ks was plotted versus p*. Finally, the results were discussed in terms of the effect of solvent on complexation.

  10. Synthesis, characterization and spectrochemical studies on a few binuclear -oxo molybdenum(V) complexes of pyrimidine derived Schiff base ligands

    Indian Academy of Sciences (India)

    Samik Gupta; Somnath Roy; Tarak Nath Mandal; Kinsuk Das; Sangita Ray; Ray J Butcher; Susanta Kumar Kar

    2010-03-01

    Ten new binuclear singly oxo-bridged molybdenum complexes (complexes 1-10) were prepared using five pyrimidine derived Schiff base ligands and two Mo(V) precursors (NH4)2MoOCl5 and (NH4)2MoOBr5. The ligands are prepared by the condensation of 4,6-dimethyl 2-hydrazino pyrimidine with salicylaldehyde (for HL1), -hydroxy acetophenone (for HL2) and substituted salicylaldehydes (for HL3, HL4 and HL5) respectively. These ligands are already reported as good donors for Mo(VI) state. The -oxo Mo(V) complexes reported here bears a distorted octahedral geometry around each Mo atom with either N2O2Cl or N2O2Br chromophores. Fine variations in the spectroscopic behaviour of the complexes are observed in accordance with the varying electron donating properties of the ligands. All the complexes are unstable in solution and X-ray quality crystal of complex 1 could be isolated. All the complexes are characterized by IR and UV-Vis spectra.

  11. 丙烯环氧化钼-醇配合物催化剂的研究%Study on Molybdenum-glycol Complex Catalyst for Epoxidation of Propylene

    Institute of Scientific and Technical Information of China (English)

    王晓晗; 卢冠忠

    2001-01-01

    Molybdenum-glycol complexes are synthesized by reacting ammonium molybdate with alkylene-glycol and characterized by IR and UV-Vis. Propylene has been epoxidized in the liquid phase with cumene hydroperoxide in the presence of molybdenum-glycol complex catalyst. Molybdenum-glycol complexes have stronger acidity and can decompose cumene hydroperoxide. Adding basic additives into the reactants may hinder the decomposition of cumene hydroperoxide. Molybdenum-glycol catalysts prepared with different glycols have different acidities and catalytic properties. Molybdenum-propylene-glycol catalyst (alcohol/molybdenum mass ratio is 4) containing lower than 10% of water and lower than 150 mg KOH/mL cat. of acidity sites, has almost similar catalytic property for the epoxidation of propylene.%合成了有机钼-醇配合物, 并用IR和UV-Vis进行了表征, 研究了对过氧化氢异丙苯(CHP)环氧化丙烯的催化性能. 研究表明, 合成的有机钼-醇化合物具有较强的酸性, 可分解CHP, 在反应物中加入碱性抑制剂可阻止CHP的分解; 不同二醇制备的化合物, 其酸性和氧化性能各不相同. 由丙二醇制备的钼-醇化合物的催化环氧化性能较好. 在醇/钼质量比为4、 水含量低于10%(质量分数)、 酸量低于150 mg KOH/mL cat.时, 催化剂的性能基本相同.

  12. Altering petrology through microbial dissimilatory phosphite oxidation

    Science.gov (United States)

    Zhu, H.; Figueroa, I.; Coates, J. D.

    2013-12-01

    Microbial enhanced oil recovery (MEOR) takes advantage of various microbial metabolisms to increase hydrocarbon and energy yield by improving oil flow and flood water sweep in a reservoir during tertiary recovery. Wormholing at the injection well is believed to be the result of the large drop in pressure when water exits the injection well and enters the unconsolidated reservoir matrix. One possible means of prevent this event is to consolidate the rock matrix immediately around the injection well to create a permeable zone of stable petrology. Many microbial processes are known to result in the precipitation of ionic components into their environment creating solid-phase minerals. Such processes could be judiciously applied to bind unconsolidated matrices in order to form a permeable concreted rock matrix, which would minimize wormholing events and thus improve floodwater sweep. However, to date, apart from the application of urea oxidation creating calcium carbonate precipitation, there has been little investigation of the applicability of these precipitated bioconcretions to MEOR strategies and none to control wormholing events. Here we present a novel approach to altering rock petrology to concrete unconsolidated matrices in the near well environment by the biogenesis of authigenic minerals through microbial dissimilatory phosphite oxidation. Desulfotignum phosphitoxidans, strain FiPS-3 is currently the only isolated organism capable of using phosphite (HPO32-) as an electron donor for growth. This process, known as dissimilatory phosphite oxidation (DPO), can be coupled to either sulfate reduction or homoacetogenesis and leads to the accumulation of inorganic phosphate in the medium. The resulting insoluble mineral phases can coat the rock environment resulting in a concretion binding the unconsolidated matrix particles into a single phase. In this study we demonstrate that DPO can effectively produce calcium or magnesium phosphate minerals in packed glass

  13. Determination of traces of Mo in soils and geological materials by solvent extraction of the molybdenum-thiocyanate complex and atomic absorption.

    Science.gov (United States)

    Kim, C H; Owens, C M; Smythe, L E

    1974-06-01

    Comprehensive studies of the extraction of the molybdenum-thiocyanate complex with methyl isobutyl ketone have resulted in an improved method for the determination of traces of molybdenum in soils and geological materials by atomic-absorption spectroscopy. The method is applicable in the range 1-500 ppm Mo, with 1-g samples, giving relative standard deviations not exceeding about 8% at a level of 1 ppm. The limit of detection is 0.1 ppm. There are few interferences, and large quantities of iron are without effect.

  14. Study on the Reaction of Proteins with 5′-Nitrosalicylfluorone-molybdenum(Ⅵ) Complex by Spectrophotometry in PVA 124 Microemulsion

    Institute of Scientific and Technical Information of China (English)

    WEI,Qin(魏琴); WU,Dana(吴丹); DU,Bina(杜斌); ZHANG,Hui(张慧); OU,Qing-Yu(欧庆瑜)

    2004-01-01

    The application of 5'-nitrosalicylfluorone (5'-NSF)-molybdenum(Ⅵ) complex as a spectroscopic probe was studied. In the buffer medium of HOAc-NaOAc at 3.45 and in the presence of PVA 124 microemulsion,5'-NSF-Mo(Ⅵ) complex combines protein rapidly to form a stable compound, leading to an absorbance decrease at 525 nm of 5'-NSF-Mo(Ⅵ) complex. According to this change, microdetermination of protein has been described.Bovine serum albumin (BSA) could be determined in the linear range of 0-16 μg·mL-1 with the detection limit of 11 ng·mL-1. Many amino acid and metal ions studied do not interfere with the assay. The method possesses high sensitivity as well as high selectivity. It can be used to determine protein in human urine and milk powder successfully. The relative standard deviations are in all instances less than 4.7%, and the recoveries are between 97.6% and 106.0%. Moreover, the binding number of BSA with the complex, which is determined by using molar ratio,Rosenthanl graphic and slope ratio methods, is in good agreement with each other.

  15. 复杂钼精矿湿法冶金工艺研究%Study on Hydrometallurgical Process for Complex Molybdenum Concentrate

    Institute of Scientific and Technical Information of China (English)

    李贺; 王海北; 王玉芳

    2013-01-01

    Rhenium-bearing complex molybdenum concentrate was oxygen pressure leached and solvent extracted.The effects of reaction time,oxygen partial pressure,ball-milling time and ratio of liquid to solid on molybdenum conversion and dissolution were investigated.The results show that molybdenum conversion rate is above 98% and molybdenum dissolution rate is about 20% under the conditions including temperature of 230 ℃,reaction time of 2.5 h,oxygen partial pressure of 600 kPa,and ratio of liquid to solid of 6.Molybdenum and rhenium are solvent extracted from pressure leaching solution.The extraction and stripping ratio of rhenium are over 97% and 99% respectively,and the extraction and stripping ratio of molybdenum are over 99% and 97%.%对低品位含铼复杂钼精矿进行氧压分解、萃取工艺研究.考察反应时间、氧分压、球磨时间、液固比等因素对钼转化率和溶出率的影响.结果表明,在230℃、反应时间2.5h、氧分压600 kPa、液固比6的条件下氧压分解,钼转化率可达到98%以上,溶出率为20%左右.氧压分解液采用分步萃取法回收钼、铼,铼萃取率和反萃率分别达到97%和99%以上,钼萃取率和反萃率分别达到99%和97%以上.

  16. Z-Selective Olefin Metathesis Processes Catalyzed by a Molybdenum Hexaisopropylterphenoxide Monopyrrolide Complex

    Science.gov (United States)

    Flook, Margaret M.; Jiang, Annie J.; Schrock, Richard R.; Müller, Peter; Hoveyda, Amir H.

    2009-01-01

    The molybdenum-based monoaryloxide monopyrrolide (MAP) species, Mo(NAd)(CHCMe2Ph)(C4H4N)(HIPTO) (2a), which contains “small” imido (Ad = 1-adamantyl) and “large” aryloxide (HIPTO = O-2,6(2,4,6-i-Pr3C6H2)C6H3) ligands, catalyzes Z-selective metathesis reactions as a consequence of intermediate metallacyclobutane species not being able to have a (anti) substituent pointing toward the HIPTO group. ROMP of dicarbomethoxynorbornadiene (DCMNBD) with 2% 2a in toluene leads to >99% cis and >99% syndiotactic poly(DCMNBD), while ROMP of cyclooctene and 1,5-cyclooctadiene (300 equiv)with initiator 2a leads to poly(cyclooctene) and poly(cyclooctadiene) that have cis contents of >99%; all are previously unknown microstructures. Z-selectivity is also observed in the metathesis of cis-4-octene and cis-3-hexene by initiator 2a to give cis-3-heptene. PMID:19462947

  17. Combination of redox-active ligand and lewis acid for dioxygen reduction with π-bound molybdenum-quinonoid complexes.

    Science.gov (United States)

    Henthorn, Justin T; Lin, Sibo; Agapie, Theodor

    2015-02-04

    A series of π-bound Mo-quinonoid complexes supported by pendant phosphines have been synthesized. Structural characterization revealed strong metal-arene interactions between Mo and the π system of the quinonoid fragment. The Mo-catechol complex (2a) was found to react within minutes with 0.5 equiv of O(2) to yield a Mo-quinone complex (3), H(2)O, and CO. Si- and B-protected Mo-catecholate complexes also react with O(2) to yield 3 along with (R(2)SiO)n and (ArBO)(3) byproducts, respectively. Formally, the Mo-catecholate fragment provides two electrons, while the elements bound to the catecholate moiety act as acceptors for the O(2) oxygens. Unreactive by itself, the Mo-dimethyl catecholate analogue reduces O(2) in the presence of added Lewis acid, B(C(6)F(5))(3), to generate a Mo(I) species and a bis(borane)-supported peroxide dianion, [[(F(5)C(6))(3)B](2)O(2)(2-)], demonstrating single-electron-transfer chemistry from Mo to the O(2) moiety. The intramolecular combination of a molybdenum center, redox-active ligand, and Lewis acid reduces O(2) with pendant acids weaker than B(C(6)F(5))(3). Overall, the π-bound catecholate moiety acts as a two-electron donor. A mechanism is proposed in which O(2) is reduced through an initial one-electron transfer, coupled with transfer of the Lewis acidic moiety bound to the quinonoid oxygen atoms to the reduced O(2) species.

  18. Substitution of gadolinium ethylenediaminetetraacetate with phosphites: towards gadolinium deposit in nephrogenic systemic fibrosis.

    Science.gov (United States)

    Gao, Song; Chen, Mao-Long; Zhou, Zhao-Hui

    2014-01-14

    In neutral media, reactions of gadolinium ethylenediaminetetraacetates with phosphorous acid result in the formation of the mixed-ligand polymeric complex K3n[Gd(EDTA)(HPO3)]n·7nH2O () and dimeric complex Na6[Gd2(EDTA)2(HPO3)2]·2.5NaCl·21H2O () (H4EDTA = ethylenediaminetetraacetic acid) in warm solution. Further substitution with citric acid gives the monomeric gadolinium citrate with EDTA (NH4)2Na[Gd(EDTA)(H2cit)]·4H2O (). The compounds were characterized by elemental analysis, single crystal X-ray diffraction, FT-IR, ESI-MS and thermogravimetric analysis. Structural analysis indicates that three coordinated water molecules in the gadolinium ethylenediaminetetraacetate trihydrates are replaced by phosphite ions (HPO3(2-)) in the compounds and . Gadolinium atoms are octa-coordinated by EDTA and the phosphite ion, the latter links adjacent Gd-EDTA units to generate an infinite one-dimensional chain in compound and a dimeric octatomic ring in . In complex , coordinated water molecules were substituted by the α-hydroxy, α-carboxy and β-carboxy groups of citrate. Citrate is favourable for inhibiting the formation of Gd-EDTA phosphite. All the complexes are very easily soluble in water. The solution behavior of the isostructural lanthanum complexes was probed with (13)C and (31)P NMR spectra in D2O for comparison. ESI-MS analysis and recrystallization proved that complexes and dissociate to the monomeric unit of Gd-EDTA and free HPO3(2-) in aqueous solution. Substitutions of gadolinium ethylenediaminetetraacetates to and are attributed to be the cause of nephrogenic systemic fibrosis in some way.

  19. Infrared Multiple Photon Dissociation Spectroscopy of a Gas-Phase Oxo-Molybdenum Complex with 1,2-Dithiolene Ligands

    Science.gov (United States)

    2015-01-01

    Electrospray ionization (ESI) in the negative ion mode was used to create anionic, gas-phase oxo-molybdenum complexes with dithiolene ligands. By varying ESI and ion transfer conditions, both doubly and singly charged forms of the complex, with identical formulas, could be observed. Collision-induced dissociation (CID) of the dianion generated exclusively the monoanion, while fragmentation of the monoanion involved decomposition of the dithiolene ligands. The intrinsic structure of the monoanion and the dianion were determined by using wavelength-selective infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The IRMPD spectrum for the dianion exhibits absorptions that can be assigned to (ligand) C=C, C–S, C—C≡N, and Mo=O stretches. Comparison of the IRMPD spectrum to spectra predicted for various possible conformations allows assignment of a pseudo square pyramidal structure with C2v symmetry, equatorial coordination of MoO2+ by the S atoms of the dithiolene ligands, and a singlet spin state. A single absorption was observed for the oxidized complex. When the same scaling factor employed for the dianion is used for the oxidized version, theoretical spectra suggest that the absorption is the Mo=O stretch for a distorted square pyramidal structure and doublet spin state. A predicted change in conformation upon oxidation of the dianion is consistent with a proposed bonding scheme for the bent-metallocene dithiolene compounds [Lauher, J. W.; Hoffmann, R. J. Am. Chem. Soc.1976, 98, 1729−1742], where a large folding of the dithiolene moiety along the S···S vector is dependent on the occupancy of the in-plane metal d-orbital. PMID:24988369

  20. Chromatographic Separation Method for the Simulant Mixture of Triisopropyl Phosphite and Bis(2-Ethylhexyl) Hydrogen Phosphite

    Science.gov (United States)

    1991-08-01

    that of diisopropyl hydrogen phosphite (DIP) that could yield an error in the purity results if coelu- tion with TIP occurs. The DIP component is a...source of potential error if it is not completely separated from the TIP. The purpose of this investigation is to perform the initial GC development...8217 Retention Time 2 (min) Area3 1. 2-propanol 1.1 981078 2. TIP 3.44 15685456 3. DIP 5.68 7205570 4. TIPO 1.15 3584104 5. --- 14.63 720318 6. 17.63

  1. Macromolecular peroxo complexes of Vanadium(V) and Molybdenum(VI): Catalytic activities and biochemical relevance

    Indian Academy of Sciences (India)

    Nashreen S Islam; Jeena Jyoti Boruah

    2015-05-01

    Our recent achievements concerning the synthesis and characterization of water soluble peroxo complexes of V(V) and Mo(VI) in macroligand environment, as well as some key features of biological relevance of these compounds, such as their hydrolytic stability, activity with phosphohydrolase enzyme vis-à-vis free peroxovanadium (pV) or peroxomolybdenum (pMo) complexes, and their activity in biomimetic oxidative bromination are presented here. Immobilization of pMo species on insoluble polymer matrices viz., amino acid functionalized Merrifield resins and poly(acrylonitrile) on the other hand, afforded a set of heterogeneous catalysts highly effective in facile organic transformations such as selective oxidation of organic sulfides and oxidative bromination of aromatic substrates by H2O2, at ambient temperature. The methodologies are straightforward, high-yielding, halogen-free and the catalysts afford easy regeneration. Our findings illustrate the various features which make the procedures sustainable and synthetically useful.

  2. Catalytic currents of hydrogen in solutions of molybdenum complexes of 8-quinolinol

    Energy Technology Data Exchange (ETDEWEB)

    Toropova, V.F.; Polyakov, Yu.N.; Bondar' , I.I.

    1987-11-20

    In the electroreduction of Mo(VI) at a dropping mercury electrode in the presence of 8-quinolinol in 2 x 10/sup -3/ M HCl in the potential range from -1.1 to -1.15 V a catalytic wave of hydrogen is observed. The catalytic current attains a maximum value in the pH range 2.4-2.8 and depends linearly on the Mo(VI) concentration in the range 10/sup -7/-2 x 10/sup -8/ M. The catalytic effect is determined by the protonation of the complex of Mo(V) with 8-quinolinol adsorbed on the electrode. An important part in the catalytic process is played by the adsorption of the Mo(V) complex, which causes a considerable rise in the catalytic current in comparison with the diffusion current.

  3. A STUDY OF FUNDAMENTAL REACTION PATHWAYS FOR TRANSITION METAL ALKYL COMPLEXES. I. THE REACTION OF A NICKEL METHYL COMPLEX WITH ALKYNES. II. THE MECHANISM OF ALDEHYDE FORMATION IN THE REACTION OF A MOLYBDENUM HYDRIDE WITH MOLYBDENUM ALKYLS

    Energy Technology Data Exchange (ETDEWEB)

    Huggins, John Mitchell

    1980-06-01

    mixed dimers MeCpMo(CO){sub 3}-(CO){sub 3}MoCp (3b) and MeCpMo(CO){sub 2}{triple_bond}(CO){sub 2}MoCp (4b) are the predominant kinetic products of the reaction. Additionally labeling the carbonyl ligands of 1a with {sup 13}CO led to the conclusion that all three of the carbonyl ligands in 1a end up in the tetracarbonyl dimers 4a if the reaction is carried out under a continuous purge of argon Trapping studies failed to find any evidence for the intermediacy of either [CpMo(CO){sub 3}]{sup -} or [CpMo(CO){sub 3}]{sup +} in this reaction. A mechanism is proposed that involves the initial migration of the alkyl ligand in 2 to CO forming an unsaturated acyl complex which reacts with 1a to give a binuclear complex containing a three center-two electron Mo-H-Mo bond. This complex then selectively looses a carbonyl from the acyl molybdenum, migrates the hydride to that same metal, and forms a metal-metal bond. This binuclear complex with the hydride and acyl ligands on one metal reductively eliminates aldehyde, and migrates a carbonyl ligand, to give 4a directly. The other product 3a is formed by addition of two molecules of free CO to 4a.

  4. Synthesis, characterization and crystal structure of new nickel molybdenum complex with the pyridine dicarboxylic acid ligand: Novel precursors for nickel molybdate nanoparticles

    Indian Academy of Sciences (India)

    HAMID EMADI; BAHAREH TAMADDONI JAHROMI; ALI NEMATI KHARAT

    2017-03-01

    A novel nickel molybdenum complex with the 2,6-pyridine dicarboxylic acid ligand was successfully synthesized and characterized by thermogravimetric analysis and single crystal X-ray crystallography. The single-crystal X-ray data revealed that the structure is a hydrated 1-D polymer with two different Ni sites.The synthesized complex was then used as a new precursor for the preparation of the related nickel molybdate nanoparticles. The crystallinity and morphology of the nickel molybdate nanoparticles were characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), and Photoluminescence (PL) spectroscopy.

  5. Coordination versus coupling of dicyanamide in molybdenum and manganese pyrazole complexes.

    Science.gov (United States)

    Arroyo, Marta; Gómez-Iglesias, Patricia; Martín-Alvarez, Jose Miguel; Alvarez, Celedonio M; Miguel, Daniel; Villafañe, Fernando

    2012-06-04

    The reactions of cis-[MoCl(η(3)-methallyl)(CO)(2)(NCMe)(2)] (methallyl = CH(2)C(CH(3))CH(2)) with Na(NCNCN) and pz*H (pzH, pyrazole, or dmpzH, 3,5-dimethylpyrazole) lead to cis-[Mo(η(3)-methallyl)(CO)(2)(pz*H)(μ-NCNCN-κ(2)N,N)](2) (pzH, 1a; dmpzH, 1b), where dicyanamide is coordinated as bridging ligand. Similar reactions with fac-[MnBr(CO)(3)(NCMe)(2)] lead to the pyrazolylamidino complexes fac-[Mn(pz*H)(CO)(3)(NH═C(pz*)NCN-κ(2)N,N)] (pzH, 2a; dmpzH, 2b), resulting from the coupling of pyrazol with one of the CN bonds of dicyanamide. The second CN bond of dicyanamide in 2a undergoes a second coupling with pyrazole after addition of 1 equiv of fac-[MnBr(CO)(3)(pzH)(2)], yielding the dinuclear doubly coupled complex [{fac-Mn(pzH)(CO)(3)}(2)(μ-NH═C(pz)NC(pz)=NH-κ(4)N,N,N,N)]Br (3). The crystal structure of 3 reveals the presence of two isomers, cis or trans, depending on whether the terminal pyrazoles are coordinated at the same or at different sides of the approximate plane defined by the bridging bis-amidine ligand. Only the cis isomer is detected in the crystal structure of the perchlorate salt of the same bimetallic cation (4), obtained by metathesis with AgClO(4). All the N-bound hydrogen atoms of the cations in 3 or 4 are involved in hydrogen bonds. Some of the C-N bonds of the pyrazolylamidino ligand have a character intermediate between single and double, and theoretical studies were carried out on 2a and 3 to confirm its electronic origin and discard packing effects. Calculations also show the essential role of bromide in the planarity of the tetradentate ligand in the bimetallic complex 3.

  6. Determining the magnitude and direction of photoinduced ligand field switching in photochromic metal-organic complexes: molybdenum-tetracarbonyl spirooxazine complexes.

    Science.gov (United States)

    Paquette, Michelle M; Patrick, Brian O; Frank, Natia L

    2011-07-06

    The ability to optically switch or tune the intrinsic properties of transition metals (e.g., redox potentials, emission/absorption energies, and spin states) with photochromic metal-ligand complexes is an important strategy for developing "smart" materials. We have described a methodology for using metal-carbonyl complexes as spectroscopic probes of ligand field changes associated with light-induced isomerization of photochromic ligands. Changes in ligand field between the ring-closed spirooxazine (SO) and ring-opened photomerocyanine (PMC) forms of photochromic azahomoadamantyl and indolyl phenanthroline-spirooxazine ligands are demonstrated through FT-IR, (13)C NMR, and computational studies of their molybdenum-tetracarbonyl complexes. The frontier molecular orbitals (MOs) of the SO and PMC forms differ considerably in both electron density distributions and energies. Of the multiple π* MOs in the SO and PMC forms of the ligands, the LUMO+1, a pseudo-b(1)-symmetry phenanthroline-based MO, mixes primarily with the Mo(CO)(4) fragment and provides the major pathway for Mo(d)→phen(π*) backbonding. The LUMO+1 is found to be 0.2-0.3 eV lower in energy in the SO form relative to the PMC form, suggesting that the SO form is a better π-acceptor. Light-induced isomerization of the photochromic ligands was therefore found to lead to changes in the energies of their frontier MOs, which in turn leads to changes in π-acceptor ability and ligand field strength. Ligand field changes associated with photoisomerizable ligands allow tuning of excited-state and ground-state energies that dictate energy/electron transfer, optical/electrical properties, and spin states of a metal center upon photoisomerization, positioning photochromic ligand-metal complexes as promising targets for smart materials.

  7. Microbial Phosphite Oxidation and Its Potential Role in the Global Phosphorus and Carbon Cycles.

    Science.gov (United States)

    Figueroa, I A; Coates, J D

    2017-01-01

    Phosphite [Formula: see text] is a highly soluble, reduced phosphorus compound that is often overlooked in biogeochemical analyses. Although the oxidation of phosphite to phosphate is a highly exergonic process (E(o)(')=-650mV), phosphite is kinetically stable and can account for 10-30% of the total dissolved P in various environments. There is also evidence that phosphite was more prevalent under the reducing conditions of the Archean period and may have been involved in the development of early life. Its role as a phosphorus source for a variety of extant microorganisms has been known since the 1950s, and the pathways involved in assimilatory phosphite oxidation have been well characterized. More recently, it was demonstrated that phosphite could also act as an electron donor for energy metabolism in a process known as dissimilatory phosphite oxidation (DPO). The bacterium described in this study, Desulfotignum phosphitoxidans strain FiPS-3, was isolated from brackish sediments and is capable of growing by coupling phosphite oxidation to the reduction of either sulfate or carbon dioxide. FiPS-3 remains the only isolated organism capable of DPO, and the prevalence of this metabolism in the environment is still unclear. Nonetheless, given the widespread presence of phosphite in the environment and the thermodynamic favorability of its oxidation, microbial phosphite oxidation may play an important and hitherto unrecognized role in the global phosphorus and carbon cycles. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Molybdenum: Industrial applications

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, W.; Fairhurst, W.; King, P.

    1982-12-01

    Molybdenum availability and molybdenum consumption are reviewed. About 9% of the total amount of molybdenum consumed is used in the production of nonferrous metals. The authors list applications for which molybdenum materials, owing to their physical and high-temperature characteristics, are particularly well suited.

  9. Molybdenum 1,4-diazabuta-1,3-diene tricarbonyl solvento complexes revisited: from solvatochromism to attractive ligand-ligand interaction.

    Science.gov (United States)

    Oelkers, Benjamin; Venker, Alexander; Sundermeyer, Jörg

    2012-04-16

    Various complexes of the types [Mo(DAD)(CO)(3)L] (L = CO, MeCN, MeOH, THF, DMSO, DMF, Me(2)CO, EtOAc, THT, Im(H), Im(1), tBuNC, nBu(3)P), (ER(4))[Mo(DAD)(CO)(3)X] (ER(4) = NEt(4)(+); X(-) = Cl(-), Br(-), I(-), NCS(-), CN(-) and ER(4)(+) = PPh(4)(+); X(-) = N(3)(-)), and (ER(4))[{Mo(DAD)(CO)(3)}(2)(μ-X)] (ER(4)(+) = NEt(4)(+); X(-) = CN(-), OAc(-) and ER(4)(+) = PPh(4)(+); X(-) = N(3)(-); DAD = N,N'-bis(2,6-dimethylphenyl)butane-2,3-diimine) were prepared by ligand exchange from cycloheptatriene molybdenum tricarbonyl. A total of 19 crystal structures were determined, including unprecedented structural characterization of molybdenum(0) coordination by dimethyl sulfoxide (DMSO), methanol, ethyl acetate (EtOAc), acetone, and N,N-dimethylformamide (DMF). Correlation of (13)C NMR shifts with the complex geometry suggests a direct ligand-ligand interaction between DAD and O-bonded coligands with C═O and S═O double bonds, such as EtOAc, Me(2)CO, DMF, and DMSO. Unexpectedly, the solvatochromic properties of these tricarbonyl complexes [Mo(DAD)(CO)(3)L] are unfavorable for the determination of Kamlet-Taft parameters of the corresponding solvent L. Contrastingly, the UV/vis absorption of [Mo(DAD)(CO)(4)] is strongly correlated with the Kamlet-Taft parameter π*, which is shown for 22 solvents, including seven room temperature ionic liquids.

  10. HYDROGEN VACANCY INTERACTION IN MOLYBDENUM

    NARCIS (Netherlands)

    Abd El Keriem, M.S.; van der Werf, D.P.; Pleiter, F

    1993-01-01

    Vacancy-hydrogen interaction in molybdenum was investigated by means of the perturbed angular correlation technique, using the isotope In-111 as a probe. The complex InV2 turned out to trap up to two hydrogen atoms: trapping of a single hydrogen atom gives rise to a decrease of the quadrupole

  11. 21 CFR 189.300 - Hydrogenated 4,4′-isopropyl-idene-diphenol-phosphite ester resins.

    Science.gov (United States)

    2010-04-01

    ...-phosphite ester resins. 189.300 Section 189.300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Surfaces § 189.300 Hydrogenated 4,4′-isopropyl-idene-diphenol-phosphite ester resins. (a) Hydrogenated 4,4′-isopropylidene-diphenolphosphite ester resins are the condensation product of 1 mole of triphenyl phosphite and...

  12. Well-Defined Molybdenum Oxo Alkyl Complex Supported on Silica by Surface Organometallic Chemistry: A Highly Active Olefin Metathesis Precatalyst.

    Science.gov (United States)

    Merle, Nicolas; Le Quéméner, Frédéric; Bouhoute, Yassine; Szeto, Kai C; De Mallmann, Aimery; Barman, Samir; Samantaray, Manoja K; Delevoye, Laurent; Gauvin, Régis M; Taoufik, Mostafa; Basset, Jean-Marie

    2017-02-15

    The well-defined silica-supported molybdenum oxo alkyl species (≡SiO-)MoO(CH2(t)Bu)3 was selectively prepared by grafting of MoO(CH2(t)Bu)3Cl onto partially dehydroxylated silica (silica700) using the surface organometallic chemistry approach. This surface species was fully characterized by elemental analysis and DRIFT, solid-state NMR, and EXAFS spectroscopy. This new material is related to the active species of industrial supported MoO3/SiO2 olefin metathesis catalysts. It displays very high activity in propene self-metathesis at mild (turnover number = 90 000 after 25 h). Remarkably, its catalytic performance outpaces those of the parent imido derivative and its tungsten oxo analogue.

  13. The efficient synthesis of a molybdenum carbide catalyst via H2-thermal treatment of a Mo(VI)-hexamethylenetetramine complex.

    Science.gov (United States)

    Wang, Zhi-Qiang; Zhang, Zhong-Biao; Zhang, Ming-Hui

    2011-02-07

    An efficient method for preparation of Mo(2)C catalyst is described, where Mo(2)C is obtained by the heat treatment of a single solid precursor containing (NH(4))(6)Mo(7)O(24) and hexamethylenetetramine (HMT) at 923 K in H(2) flow without conventional prolonged carbonization. The catalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area measurement, and transmission electron microscopy (TEM). Furthermore, these catalysts are evaluated in the dibenzothiophene (DBT) hydrodesulfurization (HDS) reaction, and proved to be superior to those prepared by a temperature-programmed reduction (TPRe) method. The better catalytic performance is ascribed to higher dispersion of Mo(2)C on the support and a lower surface polymeric carbon content. This hydrogen thermal treatment (HTT) method provided a new strategy for the preparation of a highly active molybdenum carbide catalyst.

  14. The development of a phosphite-mediated fertilization and weed control system for rice

    Science.gov (United States)

    Manna, Mrinalini; Achary, V. Mohan M.; Islam, Tahmina; Agrawal, Pawan K.; Reddy, Malireddy K.

    2016-01-01

    Fertilizers and herbicides are two vital components of modern agriculture. The imminent danger of phosphate reserve depletion and multiple herbicide tolerance casts doubt on agricultural sustainability in the future. Phosphite, a reduced form of phosphorus, has been proposed as an alternative fertilizer and herbicide that would address the above problems to a considerable extent. To assess the suitability of a phosphite-based fertilization and weed control system for rice, we engineered rice plants with a codon-optimized ptxD gene from Pseudomonas stutzeri. Ectopic expression of this gene led to improved root growth, physiology and overall phenotype in addition to normal yield in transgenic plants in the presence of phosphite. Phosphite functioned as a translocative, non-selective, pre- and post-emergent herbicide. Phosphite use as a dual fertilizer and herbicide may mitigate the overuse of phosphorus fertilizers and reduce eutrophication and the development of herbicide resistance, which in turn will improve the sustainability of agriculture. PMID:27109389

  15. 微合金钢中钛钼复合析出的第一性原理研究%Study on First Principle of Complex Precipitation of Titanium and Molybdenum in Micro-alloyed Steel

    Institute of Scientific and Technical Information of China (English)

    赵冬伟; 曹建春; 周晓龙; 彭谦之

    2012-01-01

    The formation energy of complex carbonitrides of titanium and molybdenum, which may precipitate in low alloyed steel, was computed using materials studiq-CASTEP module. The calculated results indicate that the effect of molybdenum on the formation energy of (Ti1-xMox)C presents a parasol trend. The formation energy of (Ti1-x Mox)C first decreases and then increases with increasing molybdenum content, and the maximum appears when Ti/Mo is 1. The formation energy of titanium carbide is lower than that of molybdenum carbide. Molybdenum can reduce the formation energy of (Ti1-x Mox)(CyN1-y) and the impact becomes sluggish as molybdenum content increasing. The formation energy of nitrogen-rich carbonitrides is lower than that of carbon-rich carbonitrides.%利用Materials Studio中CASTEP模块对钢中出现的钛钼复合析出相的形成能进行计算.结果表明,Mo含量对碳化钛钼形成能的影响趋势呈抛物线状,以Ti/Mo值等于1为界,随着Mo含量的增加,碳化钛钼的形成能先降低后升高;TiC的形成能比MoC的低,Mo会降低碳氮化钛钼的形成能,且降低幅度随钼含量增加逐渐减小;富氮的碳氮化钛钼比富碳的碳氮化钛钼具有更低的形成能.

  16. Potassium phosphite primes defense responses in potato against Phytophthora infestans.

    Science.gov (United States)

    Machinandiarena, Milagros Florencia; Lobato, María Candela; Feldman, Mariana Laura; Daleo, Gustavo Raúl; Andreu, Adriana Balbina

    2012-09-15

    Although phosphite is widely used to protect plants from pathogenic oomycetes on a wide range of horticultural crops, the molecular mechanisms behind phosphite induced resistance are poorly understood. The aim of this work was to assess the effects of potassium phosphite (KPhi) on potato plant defense responses to infection with Phytophtora infestans (Pi). Pathogen development was severely restricted and there was also an important decrease in lesion size in infected KPhi-treated leaves. We demonstrated that KPhi primed hydrogen peroxide and superoxide anion production in potato leaves at 12 h post-inoculation with Pi. Moreover, the KPhi-treated leaves showed an increased and earlier callose deposition as compared with water-treated plants, beginning 48 h after inoculation. In contrast, callose deposition was not detected in water-treated leaves until 72 h after inoculation. In addition, we carried out RNA gel blot analysis of genes implicated in the responses mediated by salicylic (SA) and jasmonic acid (JA). To this end, we examined the temporal expression pattern of StNPR1 and StWRKY1, two transcription factors related to SA pathway, and StPR1 and StIPII, marker genes related to SA and JA pathways, respectively. The expression of StNPR1 and StWRKY1 was enhanced in response to KPhi treatment. In contrast, StIPII was down regulated in both KPhi- and water-treated leaves, until 48 h after infection with Pi, suggesting that the regulation of this gene could be independent of the KPhi treatment. Our results indicate that KPhi primes the plant for an earlier and more intense response to infection and that SA would mediate this response.

  17. Molybdenum, molybdenum oxides, and their electrochemistry.

    Science.gov (United States)

    Saji, Viswanathan S; Lee, Chi-Woo

    2012-07-01

    The electrochemical behaviors of molybdenum and its oxides, both in bulk and thin film dimensions, are critical because of their widespread applications in steels, electrocatalysts, electrochromic materials, batteries, sensors, and solar cells. An important area of current interest is electrodeposited CIGS-based solar cells where a molybdenum/glass electrode forms the back contact. Surprisingly, the basic electrochemistry of molybdenum and its oxides has not been reviewed with due attention. In this Review, we assess the scattered information. The potential and pH dependent active, passive, and transpassive behaviors of molybdenum in aqueous media are explained. The major surface oxide species observed, reversible redox transitions of the surface oxides, pseudocapacitance and catalytic reduction are discussed along with carefully conducted experimental results on a typical molybdenum glass back contact employed in CIGS-based solar cells. The applications of molybdenum oxides and the electrodeposition of molybdenum are briefly reviewed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Synthesis and structures of bis(dithiolene)tungsten(IV,VI) thiolate and selenolate complexes: approaches to the active sites of molybdenum and tungsten formate dehydrogenases.

    Science.gov (United States)

    Groysman, Stanislav; Holm, R H

    2007-05-14

    Formate dehydrogenases are molybdenum- or tungsten-containing enzymes that catalyze the oxidation of formate to carbon dioxide. Among the significant characteristics of the mononuclear active sites are coordination of two pyranopterindithiolene ligands and selenocysteinate to the metal in oxidation states IV-VI. The first detailed investigation of the synthesis and structures of bis(dithiolene)tungsten selenolate and analogous thiolate complexes of relevance to formate dehydrogenases has been undertaken. Some 17 complexes of the types [WIV(QR)(S2C2Me2)2]-, [WVIO(QR)(S2C2Me2)2]-, and [WVIS(QR)(S2C2Me2)2]- (Q = S, Se; R = tert-butyl, 1-adamantyl) and the desoxo species [WVI(SR)(OSiR'3)(S2C2Me2)2] (R' = Me, Ph) were prepared. Ten structures of representative members of these types were determined; WIV complexes are square-pyramidal and WVI complexes are six-coordinate, with geometries intermediate between octahedral and trigonal-prismatic. Selenolate complexes are less stable than similar thiolate species; decomposition products were identified as [WV2(mu2-Q)2(S2C2Me2)2]2- and [WIV,V2(mu2-Se)(S2C2Me2)4]-. The several [MoIV(QR)(S2C2Me2)2]- complexes prepared earlier and the tungsten compounds synthesized in this work form a family of molecules whose overall stereochemistry and metric features are those expected in the absence of protein structural constraints.

  19. Determination of phosphite in a eutrophic freshwater lake by suppressed conductivity ion chromatography.

    Science.gov (United States)

    Han, Chao; Geng, Jinju; Xie, Xianchuan; Wang, Xiaorong; Ren, Hongqiang; Gao, Shixiang

    2012-10-01

    The establishment of a sensitive and specific method for the detection of reduced phosphorus (P) is crucial for understanding P cycle. This paper presents the quantitative evidence of phosphite (P, +3) from the freshwater matrix correspondent to the typically eutrophic Lake Taihu in China. By ion chromatography coupled with gradient elution procedure, efficient separation of micromolar levels of phosphite is possible in the presence of millimolar levels of interfering ions, such as chloride, sulfate, and hydrogen carbonate in freshwater lakes. Optimal suppressed ion chromatography conditions include the use of 500 μL injection volumes and an AS11 HC analytical column heated to 30 °C. The method detection limit of 0.002 μM for phosphite was successfully applied for phosphite determination in natural water samples with recoveries ranging from 90.7 ± 3.2% to 108 ± 1.5%. Phosphite in the freshwater matrix was also verified using a two-dimensional capillary ion chromatography and ion chromatography coupled with mass spectrometry. Results confirmed the presence of phosphite in Lake Taihu ranging from 0.01 ± 0.01 to 0.17 ± 0.01 μM, which correlated to 1-10% of the phosphate. Phosphite is an important component of P and may influence biogeochemical P cycle in lakes.

  20. Spectrophotometric determination of some anti-tussive and anti-spasmodic drugs through ion-pair complex formation with thiocyanate and cobalt(II) or molybdenum(V)

    Science.gov (United States)

    El-Shiekh, Ragaa; Zahran, Faten; El-Fetouh Gouda, Ayman Abou

    2007-04-01

    Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of anti-tussive drugs, e.g., dextromethorphan hydrobromide (DEX) and pipazethate hydrochloride (PiCl) and anti-spasmodic drugs, e.g., drotaverine hydrochloride (DvCl) and trimebutine maleate (TM) in bulk and in their pharmaceutical formulations. The proposed methods depend upon the reaction of cobalt(II)-thiocyanate (method A) and molybdenum(V)-thiocyanate ions (method B) with the cited drugs to form stable ion-pair complexes which extractable with an n-butnol-dichloromethane solvent mixture (3.5:6.5) and methylene chloride for methods A and B, respectively. The blue and orange red color complexes are determined either colorimetrically at λmax 625 nm (using method A) and 467 or 470 nm for (DEX and PiCl) or (DvCl and TM), respectively (using method B). The concentration range is 20-400 and 2.5-50 μg mL -1 for methods A and B, respectively. The proposed method was successfully applied for the determination of the studied drugs in pure and in pharmaceutical formulations applying the standard additions technique and the results obtained in good agreement well with those obtained by the official method.

  1. Modular chiral gold(i) phosphite complexes†Electronic supplementary information (ESI) available: Experimental results and NMR data. CCDC 933751 (L11(AuCl)), 933752 (L12(AuCl)a), 933753 (L9(AuCl)), 933754 (L10(AuCl)), 933756 (L8(AuCl)), 933757 (L12(AuCl)e). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3cy00250kClick here for additional data file.Click here for additional data file.

    Science.gov (United States)

    Delpont, Nicolas; Escofet, Imma; Pérez-Galán, Patricia; Spiegl, Dirk; Raducan, Mihai; Bour, Christophe; Sinisi, Riccardo; Echavarren, Antonio M

    2013-10-07

    Chiral gold(i) phosphite complexes are readily prepared modularly from 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol. These chiral gold(i) phosphite complexes are very reactive precatalysts for the [4+2] cycloaddition of aryl-substituted 1,6-enynes with enantiomeric ratios ranging from 86 : 14 up to 94 : 6.

  2. Microwave assisted synthesis of molybdenum and tungsten tetracarbonyl complexes with a pyrazolylpyridine ligand. Crystal structure of cis-[Mo(CO)4{ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate}].

    Science.gov (United States)

    Coelho, Ana C; Almeida Paz, Filipe A; Klinowski, Jacek; Pillinger, Martyn; Gonçalves, Isabel S

    2006-12-06

    We report the one-step syntheses in good yields of the complexes cis-[M(CO)4(pzpy)] {M = Mo, W; pzpy = ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate} directly from the corresponding M(CO)6 starting materials by using microwave-assisted heating and reaction times of either 30 s (M = Mo) or 15 min (M = W). The structure of the molybdenum tetracarbonyl complex was determined by single crystal X-ray diffraction. The compound is monomeric and the molybdenum atom has a highly distorted octahedral geometry. The close packing of the individual cis-[Mo(CO)4(pzpy)] species is essentially driven by the need to fill the space effectively, closely mediated by weak C-H-O and pi-pi interactions.

  3. Dielectric properties of ferroelectric betaine phosphite crystals with a high degree of deuteration

    Science.gov (United States)

    Balashova, E. V.; Krichevtsov, B. B.; Yurko, E. I.; Svinarev, F. B.; Pankova, G. A.

    2015-12-01

    The dielectric properties of deuterated betaine phosphite crystals with a high degree of deuteration in the region of the antiferrodistorsive (at T = T c1) and ferroelectric (at T = T c2) phase transitions have been investigated. The temperature behavior of the dielectric permittivity of betaine phosphite and deuterated betaine phosphite has been described within the framework of the Landau thermodynamic model taking into account the biquadratic coupling between the polar order parameter of the ferroelectric transition and the nonpolar order parameter of the antiferrodistorsive phase transition. It has been shown that an increase in the degree of deuteration leads to a decrease in the coupling between the order parameters. An increase in the temperature of the ferroelectric phase transition due to the deuteration of betaine phosphite is caused by an increase in the dielectric permittivity in the symmetric phase above the temperature of the antiferrodistorsive phase transition.

  4. Synthesis, characterization and biological activities of some new chromium molybdenum and tungsten complexes with 2,6-diaminopyridine.

    Science.gov (United States)

    Soliman, Ahmed A; Ali, Saadia A; Marei, Amany H; Nassar, Doaa H

    2012-04-01

    The reactions of [M(CO)6], M=Cr, Mo, W with 2,6-diaminopyridine (dap) in ethanol was carried out under sun light and microwave irradiation routes of synthesis and compared with the traditional thermal reflux method. All routes resulted in the formation of the binuclear oxo complexes with the general formulas [M2(O)4(dap)2]. The prepared complexes were characterized using elemental analysis, IR, 1HNMR, mass spectrometry and magnetic measurement. The biological activity of dap and its complexes as antibacterial and antifungal reagents have been screened.

  5. Chromium(0), molybdenum(0), and tungsten(0) isocyanide complexes as luminophores and photosensitizers with long-lived excited states

    Energy Technology Data Exchange (ETDEWEB)

    Bueldt, Laura A. [Institute of Inorganic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076, Tuebingen (Germany); Wenger, Oliver S. [Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel (Switzerland)

    2017-05-15

    Arylisocyanide complexes based on earth-abundant Group 6 d{sup 6} metals are interesting alternatives to photoactive complexes made from precious metals such as Ru{sup II}, Re{sup I}, Os{sup II}, or Ir{sup III}. Some of these complexes have long-lived {sup 3}MLCT excited states that exhibit luminescence with good quantum yields as well as nano- to microsecond lifetimes, and they are very strongly reducing. Recent studies have demonstrated that Cr{sup 0}, Mo{sup 0}, and W{sup 0} arylisocyanide complexes have great potential for applications in luminescent devices, photoredox catalysis, and dye-sensitized solar cells. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Foliar phosphite application has minor phytotoxic impacts across a diverse range of conifers and woody angiosperms.

    Science.gov (United States)

    Scott, Peter; Bader, Martin Karl-Friedrich; Williams, Nari Michelle

    2016-10-01

    Phytophthora plant pathogens cause tremendous damage in planted and natural systems worldwide. Phosphite is one of the only effective chemicals to control broad-scale Phytophthora disease. Little work has been done on the phytotoxic effects of phosphite application on plant communities especially in combination with plant physiological impacts. Here, we tested the phytotoxic impact of phosphite applied as foliar spray at 0, 12, 24 and 48 kg a.i. ha(-1) . Eighteen-month-old saplings of 13 conifer and angiosperm species native to New Zealand, and two exotic coniferous species were treated and the development of necrotic tissue and chlorophyll-a-fluorescence parameters (optimal quantum yield, Fv /Fm ; effective quantum yield of photosystem II, ΦPSII ) were assessed. In addition, stomatal conductance (gs ) was measured on a subset of six species. Significant necrosis assessed by digital image analysis occurred in only three species: in the lauraceous canopy tree Beilschmiedia tawa (8-14%) and the understory shrub Dodonaea viscosa (5-7%) across phosphite concentrations and solely at the highest concentration in the myrtaceous pioneer shrub Leptospermum scoparium (66%). In non-necrotic tissue, Fv /Fm , ΦPSII and gs remained unaffected by the phosphite treatment. Overall, our findings suggest minor phytotoxic effects resulting from foliar phosphite application across diverse taxa and regardless of concentration. This study supports the large-scale use of phosphite as a management tool to control plant diseases caused by Phytophthora pathogens in plantations and natural ecosystems. Long-term studies are required to ascertain potential ecological impacts of repeated phosphite applications. © 2016 Scandinavian Plant Physiology Society.

  7. Cyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditions

    KAUST Repository

    Li, Shenyu

    2010-04-26

    A series of N-heterocyclic carbene (NHC) complexes CpMo(CO) 2(NHC)X (NHC = IMe = 1,3-dimethylimidazol-2-ylidene, X = Br, 1; NHC = 1,3-dipropylimidazol-2-ylidene, X = Br, 2; NHC = IMes = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene, X = Br, 3; NHC = IBz = 1,3-dibenzylimidazol- 2-ylidene, X = Br, 4a, and X = Cl, 4b; NHC = 1-methyl-3-propylimidazol-2- ylidene, X = Br, 5) and [CpMo(CO)2(IMes)(CH3CN)][BF 4] (6) have been synthesized and fully characterized. The stability of metal-NHC ligand bonds in these compounds under oxidative conditions has been investigated. The thermally stable Mo(VI) dioxo NHC complex [CpMoO 2(IMes)][BF4] (9) has been isolated by the oxidation of the ionic complex 6 by TBHP (tert-butyl hydrogen peroxide). Complex 6 can be applied as a very active (TOFs up to 3400 h-1) and selective olefin epoxidation catalyst. While under oxidative conditions (in the presence of TBHP), compounds 1-5 decompose into imidazolium bromide and imidazolium polyoxomolybdate. The formation of polyoxomolybdate as oxidation products had not been observed in a similar epoxidation catalyzed by Mo(II) and Mo(VI) complexes. DFT studies suggest that the presence of Br- destabilizes the CpMo(VI) oxo NHC carbene species, consistent with the experimental observations. © 2010 American Chemical Society.

  8. Optical characterization of ferroelectric glycinium phosphite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Perumal, R.; Senthil Kumar, K. [Crystal Growth Centre, Anna University, Sardar Patel Road, Chennai, Tamil Nadu 600025 (India); Moorthy Babu, S., E-mail: babu@annauniv.ed [Crystal Growth Centre, Anna University, Sardar Patel Road, Chennai, Tamil Nadu 600025 (India); Bhagavannarayana, G. [Crystal Growth and Crystallography Section, National Physical Laboratory, CSIR, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

    2010-02-04

    Single crystals of glycinium phosphite (GPI) were grown by isothermal evaporation and conventional temperature-lowering techniques. Single crystal and powder X-ray diffraction analysis confirm the monoclinic structure of the as grown crystals. The structural perfection of the as grown crystal was determined through HRXRD analysis. FTIR and Raman analysis revealed the functional groups present in the grown crystals. The optical absorption of the grown crystal was analyzed and the refractive index values for different wavelengths were measured by prism coupling technique. Thermal stability, melting temperature and phase transition temperature of the as grown crystals were identified from TGA/DSC analysis. The dielectric impedance analysis indicates the continuous phase transition nature of the grown crystals. The mechanical strength and hardening co-efficient were determined from Vicker's microhardness measurements for different loads with constant dwell time. The growth mechanism and the defects were analyzed through chemical etching analysis from various crystallographic planes and etching periods.

  9. Potassium phosphite increases tolerance to UV-B in potato.

    Science.gov (United States)

    Soledad, Oyarburo Natalia; Florencia, Machinandiarena Milagros; Laura, Feldman Mariana; Raúl, Daleo Gustavo; Balbina, Andreu Adriana; Pía, Olivieri Florencia

    2015-03-01

    The use of biocompatible chemical compounds that enhance plant disease resistance through Induced Resistance (IR) is an innovative strategy to improve the yield and quality of crops. Phosphites (Phi), inorganic salts of phosphorous acid, are environment friendly, and have been described to induce disease control. Phi, similar to other plant inductors, are thought to be effective against different types of biotic and abiotic stress, and it is assumed that the underlying signaling pathways probably overlap and interact. The signaling pathways triggered by UV-B radiation, for instance, are known to crosstalk with other signaling routes that respond that biotic stress. In the present work, the effect of potassium phosphite (KPhi) pre-treatment on UV-B stress tolerance was evaluated in potato leaves. Plants were treated with KPhi and, after 3 days, exposed to 2 h/day of UV-B (1.5 Watt m(-2)) for 0, 3 and 6 days. KPhi pre-treatment had a beneficial effect on two photosynthetic parameters, specifically chlorophyll content and expression of the psbA gene. Oxidative stress caused by UV-B was also prevented by KPhi. A decrease in the accumulation of hydrogen peroxide (H2O2) in leaves and an increase in guaiacol peroxidase (POD) and superoxide dismutase (SOD) activities were also observed. In addition, the expression levels of a gene involved in flavonoid synthesis increased in UV-B-stressed plants only when pre-treated with KPhi. Finally, accumulation of glucanases and chitinases was induced by UV-B stress and markedly potentiated by KPhi pre-treatment. Altogether, this is the first report that shows a contribution of KPhi in UV-B stress tolerance in potato plants.

  10. CATALYTIC WAVE OF CHLORATE IONS IN THE PREZENCE OF THE MOLYBDENUM (VI - 2,3-DIHYDROXYBENZALDEHYDE COMPLEX

    Directory of Open Access Journals (Sweden)

    Ludmila Kiriyak

    2010-12-01

    Full Text Available The polarographic catalytic current in acid solutions of Mo(VI, 2,3-dihydroxybenzaldehyde (2,3-DHBA and chlorate ions has been investigated. The scheme of reactions taking place in the solutions and on the electrode has been elaborated. The increase of the catalytic current is explained by the formation of the active intermediate complex [Mo(V×2,3-DHBA (ClO3-]. The rate constant of formation for the active intermediate complex K = 2.5 × 106 mol-1 × dm3 × s-1, the activation energy of reaction Ea=14.0 kcal×mol-1 and the activation entropy ∆Sa¹= -28.3 e.u. have also been determined.

  11. Complexes of osmium, uranium, molybdenum, and tungsten with the catechol amines adrenaline, noradrenaline, dopamine, dopa, and isoproterenol

    Energy Technology Data Exchange (ETDEWEB)

    El-Hendawy, A.M.; Griffith, W.P.; Pumphrey, C.A.

    1988-07-01

    New complexes of the form trans-(OsO/sub 2/L/sub 2/)/sup 2-/ and UO/sub 2/Lcenter dotnH/sub 2/O (H/sub 2/L = adrenaline (H/sub 2/ad), noradrenaline (H/sub 2/nad), dopamine (H/sub 2/dpm), dopa (H/sub 2/dp), and isoproterenol (H/sub 2/prot)) are reported, as are cis(MO/sub 2/L/sub 2/)/sup 2-/(L = nad, dp, prot for M = Mo or W, and ad for M = W), (MO/sub 2/(Hdpm)/sub 2/) (M = Mo or W), and (Mo/sub 2/O/sub 5/(Had)/sub 2/). The structures of these species are discussed on the basis of their Raman, infrared, /sup 1/H and /sup 13/C n.m.r. spectra.

  12. Organometallic Chemistry of Molybdenum.

    Science.gov (United States)

    Lucas, C. Robert; Walsh, Kelly A.

    1987-01-01

    Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

  13. Study on the Complexation of Molybdenum(Ⅵ) with Iminodi acetic Acid and Ethylenediamine-N,N'-diacetic Acid by Specific Ion Interaction and Debye-H(u)ckel Theories

    Institute of Scientific and Technical Information of China (English)

    MAJLESI Kavosh; REZAIENEJAD Saghar

    2007-01-01

    Complexation of two ligands,iminodiacetic acid and ethylenediamine-N,N'-diacetic acid,with molybdenum(Ⅵ)was studied in aqueous solutions.Molybdenum(Ⅵ) forms a mononuclear complex with the aforementioned ligands of the type MoO3L2-.All measurements have been carried out at 25 °C and different ionic strengths ranging from 0.1 to 1.0 mol·L-1 of NaClO4,with the pH justified to 6.0.Equilibrium concentration products and stoichiometry of the complexes have been determined from a combination of potentiometric and UV spectroscopic measurements.Comparison of the ionic strength effect on these complex formation reactions has been made using a Debye-Hückel type equation and Bronsted-Guggenheim-Scatchard specific ion interaction theory (SIT).Debye-Hückel theory predicted the first order effects on simple electrolyte solutions.Interactions between the reacting species and the ionic medium were taken into account in the SIT model.All of the calculations have been done by the computer program Excel 2000.

  14. Behavior of anionic molybdenum(IV, VI) and tungsten(IV, VI) complexes containing bulky hydrophobic dithiolate ligands and intramolecular NH···S hydrogen bonds in nonpolar solvents.

    Science.gov (United States)

    Hasenaka, Yuki; Okamura, Taka-aki; Tatsumi, Miki; Inazumi, Naoya; Onitsuka, Kiyotaka

    2014-11-07

    Molybdenum(IV, VI) and tungsten(IV, VI) complexes, (Et4N)2[M(IV)O{1,2-S2-3,6-(RCONH)2C6H2}2] and (Et4N)2[M(VI)O2{1,2-S2-3,6-(RCONH)2C6H2}2] (M = Mo, W; R = (4-(t)BuC6H4)3C), with bulky hydrophobic dithiolate ligands containing NH···S hydrogen bonds were synthesized. These complexes are soluble in nonpolar solvents like toluene, which allows the detection of unsymmetrical coordination structures and elusive intermolecular interactions in solution. The (1)H NMR spectra of the complexes in toluene-d8 revealed an unsymmetrical coordination structure, and proximity of the counterions to the anion moiety was suggested at low temperatures. The oxygen-atom-transfer reaction between the molybdenum(IV) complex and Me3NO in toluene was considerably accelerated in nonpolar solvents, and this increase was attributed to the favorable access of the substrate to the active center in the hydrophobic environment.

  15. Transport and compartmentation of phosphite in higher plant cells - kinetic and 31P nuclear magnetic resonance studies

    NARCIS (Netherlands)

    Danova-Alt, R.; Dijkema, C.; Waard, de P.; Köck, M.

    2008-01-01

    Phosphite (Phi, H(2)PO(3)(-)), being the active part of several fungicides, has been shown to influence not only the fungal metabolism but also the development of phosphate-deficient plants. However, the mechanism of phosphite effects on plants is still widely unknown. In this paper we analysed upta

  16. Coordinated bifluoride ions in the first thiofluoride molybdenum triangular cluster complex: synthesis and crystal structure of K5[Mo3S4F7(FHF)2]·2H2O

    Science.gov (United States)

    Mironov, Yu. V.; Yarovoi, S. S.; Solodovnikov, S. F.; Fedorov, V. E.

    2003-08-01

    The first triangular thiofluoride cluster complex of molybdenum K5[Mo3S4F7(FHF)2]·2H2O with unexpected coordination of bifluoride ions has been synthesized by the reaction of Mo3S7Br4 with molten KHF2. The compound was characterized by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Cmc21 with four formulas in unit cell of dimensions a=15.1060(20) Å,b=8.7820(9) Å,c=14.3358(13) Å,V=1901.8(4) Å3.

  17. Neutral and Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes: Reactivity in Selected Olefin Metathesis Reactions and Immobilization on Silica.

    Science.gov (United States)

    Sen, Suman; Schowner, Roman; Imbrich, Dominik A; Frey, Wolfgang; Hunger, Michael; Buchmeiser, Michael R

    2015-09-21

    The synthesis and single-crystal X-ray structures of the novel molybdenum imido alkylidene N-heterocyclic carbene complexes [Mo(N-2,6-Me2C6H3)(IMesH2)(CHCMe2Ph)(OTf)2] (3), [Mo(N-2,6-Me2C6H3)(IMes)(CHCMe2Ph)(OTf)2] (4), [Mo(N-2,6-Me2C6H3)(IMesH2)(CHCMe2Ph)(OTf){OCH(CF3)2}] (5), [Mo(N-2,6-Me2C6H3)(CH3CN)(IMesH2)(CHCMe2Ph)(OTf)](+)BArF(-) (6), [Mo(N-2,6-Cl2C6H3)(IMesH2)(CHCMe3)(OTf)2] (7) and [Mo(N-2,6-Cl2C6H3)(IMes)(CHCMe3)(OTf)2] (8) are reported (IMesH2=1,3-dimesitylimidazolidin-2-ylidene, IMes=1,3-dimesitylimidazolin-2-ylidene, BArF(-)=tetrakis-[3,5-bis(trifluoromethyl)phenyl] borate, OTf=CF3SO3(-)). Also, silica-immobilized versions I1 and I2 were prepared. Catalysts 3-8, I1 and I2 were used in homo-, cross-, and ring-closing metathesis (RCM) reactions and in the cyclopolymerization of α,ω-diynes. In the RCM of α,ω-dienes, in the homometathesis of 1-alkenes, and in the ethenolysis of cyclooctene, turnover numbers (TONs) up to 100,000, 210,000 and 30,000, respectively, were achieved. With I1 and I2, virtually Mo-free products were obtained (<3 ppm Mo). With 1,6-hepta- and 1,7-octadiynes, catalysts 3, 4, and 5 allowed for the regioselective cyclopolymerization of 4,4-bis(ethoxycarbonyl)-1,6-heptadiyne, 4,4-bis(hydroxymethyl)-1,6-heptadiyne, 4,4-bis[(3,5-diethoxybenzoyloxy)methyl]-1,6-heptadiyne, 4,4,5,5-tetrakis(ethoxycarbonyl)-1,7-octadiyne, and 1,6-heptadiyne-4-carboxylic acid, underlining the high functional-group tolerance of these novel Group 6 metal alkylidenes.

  18. New insights into the mechanism of oxodiperoxomolybdenum catalysed olefin epoxidation and the crystal structures of several oxo-peroxo molybdenum complexes.

    Science.gov (United States)

    Herbert, Matthew; Montilla, Francisco; Álvarez, Eleuterio; Galindo, Agustín

    2012-06-21

    [Mo(O)(O(2))(2)(L)(2)] compounds (L = pz, pyrazole; dmpz, 3,5-dimethylpyrazole) were reacted stoichiometrically, in the absence of an oxidant, with cis-cyclooctene in an ionic liquid medium where selective formation of the corresponding epoxide was observed. However, this oxo-transfer reaction was not observed for some other olefins, suggesting that alternative reaction pathways exist for these epoxidation processes. Subsequently, DFT studies investigating the oxodiperoxomolybdenum catalysed epoxidation model reaction for ethylene with hydrogen peroxide oxidant were performed. The well known Sharpless mechanism was first analysed for the [Mo(O)(O(2))(2)(dmpz)(2)] model catalyst and a low energy reaction pathway was found, which fits well with the observed experimental results for cis-cyclooctene. The structural parameters of the computed dioxoperoxo intermediate [Mo(O)(2)(O(2))(dmpz)(2)] in the Sharpless mechanism compare well with those found for the same moiety within the [Mo(4)O(16)(dmpz)(6)] complex, for which the full X-ray report is presented here. A second mechanism for the model epoxidation reaction was theoretically investigated in order to clarify why some olefins, which do not react stoichiometrically in the absence of an oxidant, showed low level conversions in catalytic conditions. A Thiel-type mechanism, in which the oxidant activation occurs prior to the oxo-transfer step, was considered. The olefin attack of the hydroperoxide ligand formed upon activation of hydrogen peroxide with the [Mo(O)(O(2))(2)(dmpz)(2)] model catalyst was not possible to model. The presence of two dmpz ligands coordinated to the molybdenum centre prevented the olefin attack for steric reasons. However, a low energy reaction pathway was identified for the [Mo(O)(O(2))(2)(dmpz)] catalyst, which can be formed from [Mo(O)(2)(O(2))(dmpz)(2)] by ligand dissociation. Both mechanisms, Sharpless- and Thiel-type, were found to display comparable energy barriers and both are accessible

  19. Molybdenum complexes of biochemical interest. New coordination complexes of oxomolybdenum(V) with the tridentate ONO donor Schiff bases derived from salicylaldehydes and ethanolamine

    Energy Technology Data Exchange (ETDEWEB)

    Syamal, A.; Niazi, M.A.B.

    1985-02-01

    New oxomolybdenum(V) complexes MoOClL (where LH/sub 2/ = Schiff base) derived from ethanolamine and salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3-ethoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterised by elemental analyses, conductance, molecular weight, I.R. and electronic spectra and magnetic measurements. The Schiff bases behave as dibasic tridentate ONO donor ligands. The complexes are non-electrolytes and dimers. The complexes exhibit subnormal magnetic moments and are involved in antiferromagnetic exchange with S = 0 ground state. The complexes exhibit electronic spectral bands at ca. 13000 and ca. 17000 cm/sup -1/ due to the transitions dsub(xy)- > dsub(xz,yz) (/sup 2/B/sub 2/- > /sup 2/E) and dsub(xy)- > dsub(x2-y2) (/sup 2/B/sub 2/- > /sup 2/B/sub 1/), respectively. The ..nu..(Mo = O) frequency of the complexes is observed in the 900-970 cm/sup -1/ region. On the basis of the magnetic susceptibility, I.R. and molecular weight data a dimetallic structure with alcoholic oxygen atoms as the bridging atoms is suggested.

  20. Chemical rescue and inhibition studies to determine the role of Arg301 in phosphite dehydrogenase.

    Directory of Open Access Journals (Sweden)

    John E Hung

    Full Text Available Phosphite dehydrogenase (PTDH catalyzes the NAD(+-dependent oxidation of phosphite to phosphate. This reaction requires the deprotonation of a water nucleophile for attack on phosphite. A crystal structure was recently solved that identified Arg301 as a potential base given its proximity and orientation to the substrates and a water molecule within the active site. Mutants of this residue showed its importance for efficient catalysis, with about a 100-fold loss in k cat and substantially increased K m,phosphite for the Ala mutant (R301A. The 2.35 Å resolution crystal structure of the R301A mutant with NAD(+ bound shows that removal of the guanidine group renders the active site solvent exposed, suggesting the possibility of chemical rescue of activity. We show that the catalytic activity of this mutant is restored to near wild-type levels by the addition of exogenous guanidinium analogues; Brønsted analysis of the rates of chemical rescue suggests that protonation of the rescue reagent is complete in the transition state of the rate-limiting step. Kinetic isotope effects on the reaction in the presence of rescue agents show that hydride transfer remains at least partially rate-limiting, and inhibition experiments show that K i of sulfite with R301A is ∼400-fold increased compared to the parent enzyme, similar to the increase in K m for phosphite in this mutant. The results of our experiments indicate that Arg301 plays an important role in phosphite binding as well as catalysis, but that it is not likely to act as an active site base.

  1. Eight-term cyclic phosphites as coke deposit inhibitors and a method for producing them

    Energy Technology Data Exchange (ETDEWEB)

    Vershinin, P.V.; Chebotareva, E.G.; Kadyrova, V.Kh.; Kirpichnikov, P.A.; Pozdnev, V.V.; Vershinin, Yu.P.; Zharkova, V.M.

    1982-01-01

    It is proposed that a eight-term cyclic phosphite formula be used where R = methyl, R' = tertiary-butyl or alpha-methylcyclohexyl, R'' = tertiary-butyl, R''' = hydrogen, methyl, tertiary-butyle, bromine, X = methylene and sulfur as coke deposit inhibitors in the pyrolysis of petroleum raw materials. A method for producing the eight-term cyclic phosphite formula is proposed where a cyclic chlorophosphite formula interacts with a phenol formula in a medium of polar aprotic solvent using a base at 80-100 degrees.

  2. Molybdenum oxide nanowires: synthesis & properties

    Directory of Open Access Journals (Sweden)

    Liqiang Mai

    2011-07-01

    Full Text Available Molybdenum oxide nanowires have been found to show promise in a diverse range of applications, ranging from electronics to energy storage and micromechanics. This review focuses on recent research on molybdenum oxide nanowires: from synthesis and device assembly to fundamental properties. The synthesis of molybdenum oxide nanowires will be reviewed, followed by a discussion of recent progress on molybdenum oxide nanowire based devices and an examination of their properties. Finally, we conclude by considering future developments.

  3. Novel synthetic route to molybdenum hydrido-thiocarbamoyl and hydrosulfido-carbyne complexes by reactions of trans-Mo(N{sub 2}){sub 2}(R{sub 2}PC{sub 2}H{sub 4}PR{sub 2}){sub 2} with N,N-dimethylthioformamide

    Energy Technology Data Exchange (ETDEWEB)

    Luo, X.L.; Kubas, G.J.; Burns, C.J.; Butcher, R.J. [Los Alamos National Lab., NM (United States)

    1995-07-01

    The reactions of bis(dinitrogen)molybdenum complexes trans-Mo(N{sub 2}){sub 2}(R{sub 2}PC{sub 2}H{sub 4}PR{sub 2}){sub 2} (R = Ph, Et) with N,N-dimethylthioformamide (HC(S)NMe{sub 2}) in refluxing benzene under argon give the molybdenum hydrido-thiocarbamoyl complexes MoH({eta}{sup 2}-C(S)NMe{sub 2})(R{sub 2}PC{sub 2}H{sub 4}PR{sub 2}){sub 2} (R = Ph (1a), Et (1b)). On heating at 125{degree}C in toluene solutions, compounds 1a and 1b rearrange to form the molybdenum hydrosulfido-aminocarbyne complexes trans-Mo(SH)-(=CNMe{sub 2})(R{sub 2}PC{sub 2}H{sub 4}PR{sub 2}){sub 2} (R = Ph (2a), Et (2b)). A mechanism is proposed for this thermal rearrangement which involves migration of the hydride ligand from molybdenum to the sulfur atom of the thiocarbamoyl ligand to give the 16-electron Fischer carbene intermediate Mo-(=C(SH)NMe{sub 2})(R{sub 2}PC{sub 2}H{sub 4}PR{sub 2}){sub 2}, followed by migration of the hydrosulfido group from the carbene carbon to molybdenum. The molecular structures of compounds 1a and 2a have been determined by single-crystal X-ray diffraction studies. 30 refs., 4 figs., 4 tabs.

  4. Microwave Assisted Synthesis of Molybdenum and Tungsten Tetracarbonyl Complexes with a Pyrazolylpyridine Ligand. Crystal structure of cis-[Mo(CO4{ethyl[3-(2-pyridyl-1-pyrazolyl]acetate}

    Directory of Open Access Journals (Sweden)

    Isabel S. Gonçalves

    2006-12-01

    Full Text Available We report the one-step syntheses in good yields of the complexes cis-[M(CO4(pzpy] {M = Mo, W; pzpy = ethyl[3-(2-pyridyl-1-pyrazolyl]acetate} directlyfrom the corresponding M(CO6 starting materials by using microwave-assisted heatingand reaction times of either 30 s (M = Mo or 15 min (M = W. The structure of themolybdenum tetracarbonyl complex was determined by single crystal X-ray diffraction.The compound is monomeric and the molybdenum atom has a highly distorted octahedralgeometry. The close packing of the individual cis-[Mo(CO4(pzpy] species is essentiallydriven by the need to fill the space effectively, closely mediated by weak C–H···O andπ···π interactions.

  5. Electromembrane extraction with alkylated phosphites and phosphates as supported liquid membranes

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2017-01-01

    A range of alkylated phosphates and phosphites were for the first time investigated as potential supported liquid membranes (SLMs) for electromembrane extraction (EME) of basic drugs from human plasma samples. Six polar basic drugs were used as model analytes for initial testing of the different ...

  6. Hydroformylation of methyl-3-pentenoate over a phosphite ligand modified Rh/SiO2 catalyst

    Institute of Scientific and Technical Information of China (English)

    Xianming Li; Yunjie Ding; Guiping Jiao; Jingwei Li; Li Yan; Hejun Zhu

    2008-01-01

    A phosphite ligand modified Rh/SiO2 catalyst has been developed for hydroformylation of internal olefins to linear aldehydes, which showed high activity and regioselectivity and could be separated easily by filtration after reaction in an autoclave. Effects of reaction temperature and syngas pressure on the performances of the catalyst in the reaction were also investigated.

  7. Trunk applications of phosphite for the control of foliar and fruit scab

    Science.gov (United States)

    Pecan scab (Fusicladium effusum) is the major disease of pecan in the south-eastern US. Apart from issues of fungicide resistance and the need to test efficacy of novel fungicides such as phosphites, management of the disease in tall trees is challenging due to the technical difficulties of getting ...

  8. One-pot conversion reactions of glycosyl boranophosphates into glycosyl phosphate derivatives via acyl phosphite intermediates.

    Science.gov (United States)

    Sato, Kazuki; Wada, Takeshi

    2016-11-29

    A one-pot synthesis of glycosyl phosphates and their P-modified analogs from glycosyl boranophosphates under mild basic conditions has been conducted. (31)P NMR monitoring of the reaction mixture revealed that the key intermediates of these reactions were acyl phosphites, which could not be formed from the corresponding H-phosphonate diesters.

  9. Phosphite Ligand Modified Supported Rhodium Catalyst for Hydroformylation of Internal Olefins to Linear Aldehydes

    Institute of Scientific and Technical Information of China (English)

    LI Xian-ming; DING Yun-jie; JIAO Gui-ping; LI Jing-wei; YAN Li; ZHU He-jun

    2009-01-01

    A phosphite ligand modified heterogeneous catalyst was developed for the hydroformylation of internal olefins to linear aldehydes, which showed a high activity and high regioselectivity and could be separated easily by filtration after reaction in an autoclave. Three nanoporous silica sieves were used to investigate the influence of pore structure and shape selective performance of support on the regioselectivity to the linear products.

  10. Silylene hydride complexes of molybdenum with silicon-hydrogen interactions: neutron structure of (eta(5)-C(5)Me(5))(Me(2)PCH(2)CH(2)PMe(2))Mo(H)(SiEt(2)).

    Science.gov (United States)

    Mork, Benjamin V; Tilley, T Don; Schultz, Arthur J; Cowan, John A

    2004-08-25

    Reduction of CpMoCl(4) with 3.1 equiv of Na/Hg amalgam (1.0% w/w) in the presence of 1 equiv of dmpe and 1 equiv of trimethylphosphine afforded the molybdenum(II) chloride complex Cp(dmpe)(PMe(3))MoCl (1) (Cp = 1,2,3,4,5-pentamethylcyclopentadienyl, dmpe = 1,2-bis(dimethylphosphino)ethane). Alkylation of 1 with PhCH(2)MgCl proceeded in high yield to liberate PMe(3) and give the 18-electron pi-benzyl complex Cp(dmpe)Mo(eta(3)-CH(2)Ph) (2). Variable temperature NMR experiments provided evidence that 2 is in equilibrium with its 16-electron eta(1)-benzyl isomer [Cp(dmpe)Mo(eta(1)-CH(2)Ph)]. This was further supported by reaction of 2 with CO to yield the carbonyl benzyl complex Cp(dmpe)(CO)Mo(eta(1)-CH(2)Ph) (3). Complex 2 was found to react with disubstituted silanes H(2)SiRR' (RR' = Me(2), Et(2), MePh, and Ph(2)) to form toluene and the silylene complexes Cp(dmpe)Mo(H)(SiRR') (4a: RR' = Me(2); 4b: RR' = Et(2); 4c: RR' = MePh; 4d: RR' = Ph(2)). Reactions of 2 with monosubstituted silanes H(3)SiR (R = Ph, Mes, Mes = 2,4,6-trimethylphenyl) produced rare examples of hydrosilylene complexes Cp(dmpe)Mo(H)Si(H)R (5a: R = Ph; 5b: R = Mes; 5c: R = CH(2)Ph). Reactivity of complexes 4a-c and 5a-d is dominated by 1,2-hydride migration from metal to silicon, and these complexes possess H.Si bonding interactions, as supported by spectroscopic and structural data. For example, the J(HSi) coupling constants in these species range in value from 30 to 48 Hz and are larger than would be expected in the absence of H.Si bonding. A neutron diffraction study on a single crystal of diethylsilylene complex 4b unequivocally determined the hydride ligand to be in a bridging position across the molybdenum-silicon bond (Mo-H 1.85(1) A, Si-H 1.68(1) A). The synthesis and reactivity properties of these complexes are described in detail.

  11. Extraction and determination of molybdenum with tributyl phosphate Application to analysis of copper-molybdenum ores.

    Science.gov (United States)

    Caiozzi, M; Zunino, H; Sepúlveda, L

    1969-12-01

    A differential spectrophotometric method is described for the determination of molybdenum by means of solvent extraction with tributylphosphate of the peroxymolybdate complex formed with H(2)O(2) in 3.5N H(2)SO(4). The extraction parameters are studied, and the behaviour of some other ions is reported. The method is used for ore analysis.

  12. Ionic Liquid-Mediated, Rapid N-Alkylation of Heterocyclic Compounds with Trialkyl Phosphites in the Presence of Dialkyl Acetylenedicarboxylates

    Directory of Open Access Journals (Sweden)

    Alireza Hassanabadi

    2012-01-01

    Full Text Available Ionic liquids such as 1,3-dialkylimidazolium bromides and make excellent solvents for N-alkylation of heterocyclic compounds such as saccharin and rhodanine with trialkyl phosphites in the presence of dialkyl acetylenedicarboxylates.

  13. An efficient method for the synthesis of dialkyl chlorophosphates from trialkyl phosphites using bis(trichloromethyl) carbonate

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Chuan Ming Yu; Zhi Wei Chen; Wei Ke Su

    2008-01-01

    A mild and simple method for the synthesis of dialkyl clalorophosphates is described, bis(trichloromethyl) carbonate (BTC) is used as the effective reagent for the conversion of dialkyl phosphites to their corresponding dialkyl chlorophosphates under mild conditions.

  14. Studies on the Reaction of Salicylic Acid with Dialkyl Phosphite by Electrospray Ionization Mass Spectrometry and 31p NMR

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Lan; QU Lin-Bo; GUO Lei; LU Jian-Sha; LIAO Xin-Cheng; ZHAO Yu-Fen

    2003-01-01

    @@ The Atherton-Todd reaction has been extensively applied to the synthesis of phosphates and phosphoroami dates. [1] Zeng et al. [2] suggested that under Atheron-Todd reaction conditions, dialkyl phosphites are transformed into diakyl phosphorochloridates.

  15. Isolation and assessment of the molecular and electronic structures of azo-anion-radical complexes of chromium and molybdenum. Experimental and theoretical characterization of complete electron-transfer series.

    Science.gov (United States)

    Joy, Sucheta; Krämer, Tobias; Paul, Nanda D; Banerjee, Priyabrata; McGrady, John E; Goswami, Sreebrata

    2011-10-17

    The reaction of 3 equiv of the ligand 2-[(2-chlorophenyl)azo]pyridine (L(a)) or 2-[(4-chlorophenyl)azo]pyridine (L(b)) with 1 equiv of Cr(CO)(6) or Mo(CO)(6) in boiling n-octane afforded [Cr(L(a/b))(3)](0) (1a and 1b) and [Mo(L(a/b))(3)](0) (2a and 2b). The chemical oxidation reaction of these neutral complexes with I(2) in CH(2)Cl(2) provided access to air-stable one-electron-oxidized species as their triiodide (I(3)(-)) salts. The electronic structures of chromium and molybdenum centers coordinated by the three redox noninnocent ligands L(a/b) along with their redox partners have been elucidated by using a host of physical methods: X-ray crystallography, magnetic susceptibility measurements, nuclear magnetic resonance, cyclic voltammetry, absorption spectroscopy, electron paramagnetic resonance spectroscopy, and density functional theory. The four representative complexes, 1a, [1a]I(3), 2a, and [2a]I(3), have been characterized by X-ray crystallography. The results indicate a predominant azo-anion-radical description of the ligands in the neutral chromium(III) species, [Cr(III)(L(•-))(3)], affording a singlet ground state through strong metal-ligand antiferromagnetic coupling. All of the electrochemical processes are ligand-based; i.e., the half-filled (t(2g))(3) set of the Cr(III) d(3) ion remains unchanged throughout. The description of the molybdenum analogue is less clear-cut because mixing between metal- and ligand-based orbitals is more significant. On the basis of variations in net spin densities and orbital compositions, we argue that the oxidation events are again primarily ligand-based, although the electron density at the molybdenum center is clearly more variable than that at the chromium center in the corresponding series [1a](+), 1a, and [1a](-).

  16. Asymmetric induction by the cholestanic moiety on tropos species: synthesis and stereochemical characterization of bile acid-based biphenyl phosphites.

    Science.gov (United States)

    Iuliano, A; Facchetti, S; Uccello-Barretta, G

    2006-06-23

    Three different bile acid-derived biphenyl phosphites were synthesized, starting from cholic and deoxycholic acids and biphenol, and their stereochemical features were checked by CD and NMR spectroscopies. On the basis of the spectroscopic results, the capability of the cholestanic system to induce a prevalent sense of twist on the biphenyl moiety of the bile acid-derived phosphites as well as their tropos nature was inferred.

  17. On the discovery and development of tandem 1,4- and 1,2-addition of phosphites to 1-azadienes

    OpenAIRE

    Van Waes, Frederik; Debrouwer, Wouter; Heugebaert, Thomas; Stevens, Christian

    2014-01-01

    Over the past 15 years we have developed a one-step protocol for the synthesis of 3-phosphonylated aminophosphonates from alpha,beta-unsaturated imines through tandem 1,4-1,2-phosphite addition. This account covers the initial development, mechanistic implications of using different phosphite nucleophiles and the expansion towards oximes, hydrazones and unsaturated imines included in aromatic sextets, e. g. quinolines, phenanthrolines and napthyridines.

  18. Well-defined silica supported bipodal molybdenum oxo alkyl complexes: a model of the active sites of industrial olefin metathesis catalysts

    KAUST Repository

    Merle, Nicolas

    2017-09-25

    A well-defined, silica-supported molybdenum oxo alkyl species, ([triple bond, length as m-dash]SiO-)2Mo([double bond, length as m-dash]O)(CH2tBu)2, was prepared by the selective grafting of Mo([double bond, length as m-dash]O)(CH2tBu)3Cl onto a silica partially dehydroxylated at 200 °C using a rigorous surface organometallic chemistry approach. The immobilized bipodal surface species, partly resembling the active species of industrial MoO3/SiO2 olefin metathesis catalysts, exhibited excellent functional group tolerance in conjunction with its high activity in homocoupling, self and ring closing olefin metathesis.

  19. On Separating Molybdenum from Tungsten by Solvent Extraction with Mixed Extractant Using H2O2 as Complex Agent%混合萃取剂双氧水络合萃取分离钨钼的初步研究

    Institute of Scientific and Technical Information of China (English)

    欧惠; 张贵清; 关文娟; 肖连生

    2011-01-01

    This paper studies the separation of molybdenum from tungsten by solvent extraction using the hydrogen peroxide as complex agent from ammonium tungstate solution containing high molybdenum. The effects of equilibrium time, the dosage of H2O2, equilibrium pH value of water phase, temperature on separation of Mo from WO3 are investigated. The extraction isothermal for Mo was plotted and stripping method was explored. The results indicate that, the extraction system has a favorable capability for molybdenum extraction and a good separation efficiency for molybdenum and tungsten. The saturated capacity of organic phase containing 45 % mixed extrantant for molybdenum is 9.2 g/L. The separation coefficient for molybdenum and tungsten can be more than 50. The loaded organic phase can be stripped easily with NaOH solution.%以双氧水为络合剂,采用混合萃取剂进行了高铝钨酸铵工业料液络合萃取分离钨钢的初步试验研究.试验考察了振荡平衡时间、双氧水用量、水相平衡pH值、温度等因素对钨钼萃取分离的影响,绘制了钼的萃取等温线并探索了反萃取方法.研究结果表明,该萃取体系具有良好的萃钼能力和钨钼分离性能,混合萃取剂浓度为45%的有机相对铝的饱和萃取容量达9.2g/L,单级萃取钼钨分离系数可达50以上,NaOH溶液能有效反萃负载有机相.

  20. A novel 3D framework indium phosphite-oxalate based on a pcu-type topology

    Science.gov (United States)

    Zuo, Mengmeng; Zhou, Mingdong; Hu, Dianwen; Gao, Fan; Dong, Sijie; Huang, Liangliang

    2016-05-01

    A new inorganic-organic hybrid indium phosphite-oxalate, formulated as H[In5(HPO3)6(H2PO3)2(C2O4)2]·(C4N2H11)2·H2O 1 has been hydrothermally synthesized in the presence of piperazine acting as a structure directing agent (SDA). The single crystal X-ray diffraction reveals that compound 1 shows three-dimensional open-framework with intersecting 12-ring channels along the [010] and [001] directions, which is constructed from strictly alternating double 6-ring units (D6Rs), [C2O4]2- groups and [H2PO3]- pseudo-pyramids. It is noted that the classical D6R SBU is firstly reported in main metal phosphite/phosphite-oxalate. By regarding D6R as the 6-connected nodes, the inorganic-organic hybrid framework is based on a pcu-type topology. The as-synthesized product was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), ICP-AES and elemental analyses.

  1. Theoretic Insight into CO2 Reduction at Active Sites of Molybdenum and Tungsten Enzymes: a {\\pi} Interaction between CO2 and Tungsten Bis-Dithiolene Complexes

    CERN Document Server

    Yan, Yong

    2014-01-01

    Active sites of molybdenum and tungsten enzymes, particularly mononuclear tungsten formate dehydrogenase (FDH) have been theoretically investigated towards their interaction with CO2. Obvious {\\pi} interaction has been found between the 2e reduced metallodithiole moiety and the molecular CO2. This weak {\\pi} bonding is predicated both at gas phase, noted as -6.0 kcal/mol and aqueous solvation level, -3.6 kcal/mol. Such interaction is not only limited to CO2, but also to the CO2 reduced product, i.e. formate, in the form of anion- {\\pi} interaction, noted as -6.8 kcal/mol and -4.1 kcal/mol respectively in gas and aqueous solvation model. The Bailar twisted angles from 60o to 0o, governing structure preference of tungsten dithiolene from octahedron to triangle prism in their restricted structures, has been explored to evaluate such {\\pi} in-terrelations with CO2 and formate. An octahedral structure with 3 kcal/mol energy lower is preferred over the triangle prismatic when such interactions are concerned.

  2. Preparation and Characterization of a Molybdenum(VI Schiff Base Complex as Magnetic Nanocatalyst for Synthesis of 2-Amino-4H-benzo[h]chromenes

    Directory of Open Access Journals (Sweden)

    Naghmeh Divsalar

    2016-10-01

    Full Text Available A new recoverable molybdenum nanocatalyst was prepared by immobilization  of a Schiff base ligand on the surface of silica coated magnetite nanoparticles (Fe3O4@SiO2 through condensation reaction between 3-aminopropyl triethoxysilane and 2-hydroxy1-naphthaldehyde and succeeding reaction with dioxomolybdenum(VI acetylacetonate (MoO2(acac2. The synthesized catalyst was characterized by inductively coupled plasma, thermogravimetric analysis, scanning electron microscopy, vibrating sample magnetometry, Energy-dispersive X-ray, Fourier transform infrared and X-raydiffraction spectroscopy. Catalytic performance of the synthesized nanocatalyst was investigated for the preparation of 2-amino-4H-benzo[h]chromenes. The compounds were prepared high yield through one-pot, three-component reaction of 1-naphthol, various of aldehydes and malonitrile in the presence of nanocatalyst, Fe3O4@SiO2@Mo-Schiff base, under solvent-free conditions. The benefits of this protocol are short reaction time, simple work-up procedure, high yields and use of the concept of green chemistry. The magnetic nanocatalyst could be separated easily from the reaction media using an external magnetic field and reused in subsequent catalytic runs without significant deterioration of its activity.

  3. Sulphur-bridged ruthenium-molybdenum complexes: [(R-aapm)2Ru(-S)2 Mo(OH)2]. Synthesis, spectroscopic and electro-chemical characterization. R-aapm = 2-(arylazo)pyrimidine

    Indian Academy of Sciences (India)

    Prithwiraj Byabartta

    2006-03-01

    The reaction of ctc-[Ru(R-aapm)2Cl2] (1) with (NH4)2MoS4 in aqueous MeOH afforded redviolet mixed ligand complexes of the type [(R-aapm)2Ru(-S)2Mo(OH)2] (2a-2e) [R-aapm = 2-(arylazo) pyrimidine, -R-C6H4-N=N-C4H3NN, R = H (2a), Me (2b), Cl (2c), OMe (2d), NO2 (2e)]. In complexes (2a-2e) the terminal Mo=S bonds of the MoS$_{4}^{2-}$ unit get hydroxylated and the molybdenum ion is reduced from the starting MoVI in MoS$_{4}^{2-}$ to MoIV in the final product. The solution electronic spectra exhibit a strong MLCT band at 550-570 nm in DCM. The 1H NMR spectra confirms the geometry of the complexes as being that of cis-trans-cis isomers. Cyclic voltammograms show a Ru(III)/Ru(II) couple at 1.10-1.4 V, irreversible Mo(IV)/Mo(V) oxidations in the 1.66-1.72 V range, along with four successive reversible ligand reductions in the range -0.45-0.67 V (one electron), -0.82-1.12 V (one electron), -1.44-1.90 V (simultaneously two electrons).

  4. Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

    Science.gov (United States)

    Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

    2017-01-01

    The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

  5. Mineral resource of the month: molybdenum

    Science.gov (United States)

    Polyak, Désire E.

    2011-01-01

    The article offers information about the mineral molybdenum. Sources includes byproduct or coproduct copper-molybdenum deposits in the Western Cordillera of North and South America. Among the uses of molybdenum are stainless steel applications, as an alloy material for manufacturing vessels and as lubricants, pigments or chemicals. Also noted is the role played by molybdenum in renewable energy technology.

  6. Molybdenum Metallopharmaceuticals Candidate Compounds - The "Renaissance" of Molybdenum Metallodrugs?

    Science.gov (United States)

    Jurowska, Anna; Jurowski, Kamil; Szklarzewicz, Janusz; Buszewski, Boguslaw; Kalenik, Tatiana; Piekoszewski, Wojciech

    2016-01-01

    Metal-based drugs, also called "metallopharmaceuticals" or "metallodrugs", are examples of sophisticated compounds that have been used in inorganic medicinal chemistry as therapeutic agents for a long time. Few of them have shown substantially promising results and many of them have been used in different phases of clinical trials. The Mo-based metallodrugs were successfully applied in the past for treating conditions such as anemia or Wilson's disease. Moreover, Mo complexes are supposed to exert their effect by intercalation/ cleavage of DNA/RNA, arrest of the cell cycle, and alteration of cell membrane functions. However, in the current literature, there are no reliable and in-depth reviews about the hypothetical therapeutic applications of all of the known molybdenum complexes as metallopharmaceuticals/ metallodrugs. The main emphasis was on the in-depth review of the potential applications of Mo-based complexes in medicinal chemistry as metallopharmaceuticals in treating diseases such as cancer and tumors, Wilson's disease, diabetes mellitus, Huntington's disease, atherosclerosis, and anemia. It must be emphasized that today the development of innovative and new Mo-based metalo-pharmaceuticals is not rapid, and hence the aim of this paper was also to inspire colleagues working in the field of Mo compounds who are trying to find "signpost" for research. The authors hope that this article will increase interest and initiate the Renaissance of Mo-compounds among medicinal inorganic chemists. This paper is the first review article in the literature that refers to and emphasizes many different and complex aspects of possible applications and capabilities of Mo-based metallodrugs.

  7. PRE-PLANTING TREATMENTS WITH PHOSPHITE-BASED PRODUCTS AGAINST DIFFERENT FOLIAR AND SOIL-BORNE PATHOGENS OF VEGETABLE CROPS.

    Science.gov (United States)

    Gilardi, G; Demarchi, S; Ramon, I; Gullino, M L; Garibaldi, A

    2015-01-01

    Fifteen experimental trials were carried out under greenhouse conditions to evaluate the efficacy of preventative treatments based on phosphite salts on the following pathosystems: tomato/Phytophthora nicotianae, zucchini/P. capsici, lettuce/Fusarium oxysporum f.sp. Iactucae, rocket/Fusarium oxysporum f. sp. raphani, wild rocket/Plectosphaerella cucumerina and basii/Peronospora belbahrii. The possible use of phosphite salts in nursery cultivation systems is considered in comparison with chemical fungicides. Phosphites-based products reduced 66-88% and 56-72% the severity of Phytophthora crown root rot of tomato and zucchini, respectively. Four application with the phosphites-based products provided a disease reduction of Fusarium wilt of lettuce from of 33 to 83% and of 45 to 68% on cultivated rocket. These products provide the most constant results when applied in three treatments against Plectosphaerella cucumerina with a disease reduction ranging between 34%-82%. Phosphite-based products showed results statistically similar to mefenoxam when tested against downy mildew of basil. Their contribution to disease management can be very interesting, because they can complement other control measures.

  8. Molybdenum Tube Characterization report

    Energy Technology Data Exchange (ETDEWEB)

    Beaux II, Miles Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Usov, Igor Olegovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-07

    Chemical vapor deposition (CVD) techniques have been utilized to produce free-standing molybdenum tubes with the end goal of nuclear fuel clad applications. In order to produce tubes with properties desirable for this application, deposition rates were lowered requiring long deposition durations on the order of 50 hours. Standard CVD methods as well as fluidized-bed CVD (FBCVD) methods were applied towards these objectives. Characterization of the tubes produced in this manner revealed material suitable for fuel clad applications, but lacking necessary uniformity across the length of the tubes. The production of freestanding Mo tubes that possess the desired properties across their entire length represents an engineering challenge that can be overcome in a next iteration of the deposition system.

  9. Facile synthesis of tin phosphite nanosheets via exfoliated bulk crystals: Electronic structure and piezoelectric property.

    Science.gov (United States)

    Song, Jun-Ling; Zhang, Xi-Rui; Lu, Rui-Feng

    2016-08-01

    Tin phosphite nanosheets were synthesized by a facile exfoliation method. SnHPO3 nanosheets with a thickness of ∼2.6nm readily form a stable colloidal suspension in ethanol using ultrasonic method. Structures and optical properties of the obtained nanosheets were investigated. The prepared SnHPO3 nanosheets exhibit an obvious blue-shift in UV absorbance compared with bulk SnHPO3 crystal materials. Moreover, the piezoelectric coefficients of SnHPO3 monolayer were calculated based on density functional theory, which are larger than that of h-BN monolayer, indicating this material could be a good candidate for designing electro-optical nano-devices.

  10. The investigation of molybdenum migration in aqueous media landscape of the Khibiny massif to develop environmental activities

    Directory of Open Access Journals (Sweden)

    Sulimenko L.P.

    2015-06-01

    Full Text Available Relations of natural and technogenic factors at forming of molybdenum making streams in superficial and underground waters in the Khibiny massif have been studied. The priority sources of receipt of molybdenum in water objects have been considered. Taking into account hydrogeochemistrical properties of molybdenum the terms of strategy of decline of its negative influence on superficial currents in the conditions of productive mining complex activity have been defined

  11. A novel tridentate Schiff base dioxo-molybdenum(VI) complex: synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, ¹H NMR and ¹³C NMR spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

    2012-09-01

    A new dioxo-molybdenum(VI) complex [MoO(2)(L)(H(2)O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H(2)L) and MoO(2)(acac)(2). The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the UV-visible, FTIR, (1)H NMR and (13)C NMR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TDDFT) method is used to calculate the electronic transitions of the complex. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental (1)H NMR spectra. However, the (13)C NMR shielding tensors computed at the B3LYP level, employing a combined basis set of DGDZVP for Mo and 6-31+G(2df,p) for other atoms, are in better agreement with experimental (13)C NMR spectra. The electronic transitions calculated at the B3LYP/DGDZVP level by using TD-DFT method is in accordance with the observed UV-visible spectrum of the compound. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. DFT Study of the Molybdenum-Catalyzed Deoxydehydration of Vicinal Diols

    DEFF Research Database (Denmark)

    Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes Rytter

    2015-01-01

    The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an MoVI oxo complex, oxidative cleavage of the diol resulting in an MoIV complex......, and extrusion of the alkene. We have compared the proposed pathway with several alternatives, and the results have been corroborated by comparison with the molybdenum- catalyzed sulfoxide reduction recently published by Sanz et al. and with experimental observations for the DODH itself. Improved understanding...... of the mechanism should expedite future optimization of molybdenum-catalyzed biomass transformations....

  13. Synthesis and characterization of three new beryllium phosphate/phosphites with different structure-directing agents

    Science.gov (United States)

    Pan, Jie; Xue, Zhen-Zhen; Li, Jin-Hua; Wei, Li; Wang, Guo-Ming

    2017-03-01

    Three new organically templated beryllium phosphate and phosphites, [C2H8N][Be2(PO4) (HPO4) (H2O)]·(H2O)0.5 (1), [C3H12N2][Be3(HPO3)4] (2) and [C6H18N2][Be3(HPO3)4] (3), have been synthesized and structurally characterized by single-crystal X-ray diffraction analyses. The structure of 1 consists of BeO4 and PO4 tetrahedra, displaying a double-layered structure with [Be4(PO4)2(HPO4)2(H2O)2] D4R-analogue as SBUs. Compound 2 presents a three-dimensional (3D) interrupted open-framework, constructed from two-dimensional layers pillared by phosphite nodes. Left- and right-handed helical channels occurred along the [010] direction in 2. For 3, adjacent sheets arrange in an -ABAB- staggered stacking mode to give a (3,4)-connected 3D structure with zigzag 12-ring channels. In 1-3, different protonated amine templates reside in the voids of structures and interact with the inorganic frameworks through hydrogen-bonds.

  14. The Activity and Theoretical Interpretation of Role of Trimethyl Phosphite Modified HZSM-5 Zeolite

    Institute of Scientific and Technical Information of China (English)

    Lü Renqing; Zhao Zhiyong; Cao Zuogang; Liu Chenguang

    2004-01-01

    The catalytic activity of trimethyl phosphite modified HZSM-5 zeolite and un-modified HZSM-5zeolite treated with 100% steam at 673,773,873,973 and 1073K, respectively, were investigated using heptanecracking as a probe reaction. The results showed that the heptane conversion of both trimethyl phosphitetreated samples and un-phosphated samples decreased with an increase in treating temperature, but trimethylphosphite modified samples showed higher activity in comparison with the un-modified samples, which weresteam-treated at a higher temperature. The results were firstly elucidated by the model cluster method andcomputational quantum chemistry method. Full optimization and frequency analysis of all cluster model havebeen carried out using the Gaussian 94 software-package with the PM 3 semi-empirical method performed onsmall cluster models. The computational results showed that the dealumination of trimethyl phosphite modi-fied zeolite model cluster was more difficult than that of un-modified zeolite model cluster when they weretreated with steam while investigating the heat of reaction.

  15. Synthesis, Characterization and Magnetic Properties of a New Manganese(Ⅱ) Phosphite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; WANG Li-ping; SHI Su-hua; HUANG Liang-liang; WANG Li

    2012-01-01

    A new manganese(Ⅱ) phosphite,Mn2F2(HPO3)(1),was synthesized with tetraethylene pentamine as structure directing agent under hydrothermal conditions.The as-synthesized product was characterized by single crystal X-ray diffraction,powder X-ray diffraction,infrared(IR),UV-Vis spectrum,thermogravimetric analysis(TGA),inductive coupled plasma-atomic emission spectroscopy(ICP-AES),elemental analyses and magnetic susceptibility measurement.Single crystal X-ray diffraction analysis reveals that compound 1 crystallized in the orthorhombic space group Pnma,with a=0.75667(15) nm,b=1.0247(2) nm,c=0.55432(11) nm,V=0.42980(15) nm3,Z=4.The 3Dcompact framework of compound 1 was built up by the Mn2O6F4 dimers and HPO3 pseudo-pyramids.Compound 1,a new metal-rich manganese phosphite,shows a high thermal stability limit of 550 ℃.Magnetic measurement indicates that compound 1 exhibits the global antiferromagnetic interactions with a ferromagnetic transition at 28 K.

  16. Study on the Reaction of Salicylic Acid with Dialkyl Phosphite by NMR and Electrospray Ionization Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    陈晓岚; 屈凌波; 郭蕾; 卢建莎; 刘艳; 吴建丽; 赵玉芬

    2005-01-01

    The reaction between salicylic acid and dialkyl phosphite was traced by electrospray ionization mass spectrometry and 31P NMR. All reactants, unstable intermediates and products were detected. The mechanism was proposed based on ESI-MS results and 31P NMR profiles.

  17. Construction of two novel indium phosphites with (3,6)- and (3,5)-connected frameworks: Synthesis, structure and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Li Huiduan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Department of Chemistry and Life Science, Chuxiong Normal University, Chuxiong 675000 (China); Zhang Lirong; Huo Qisheng [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu Yunling, E-mail: yunling@jlu.edu.cn [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)

    2013-01-15

    Two novel anionic indium phosphites, formulated as [H{sub 3}O][In(HPO{sub 3}){sub 2}] (1) and [C{sub 4}H{sub 12}N{sub 2}][In{sub 2}(HPO{sub 3}){sub 3}(C{sub 2}O{sub 4})] (2), were prepared under hydrothermal conditions by using piperazine (PIP) as a structure-directing agent (SDA). Single-crystal X-ray diffraction analysis reveals that compounds 1 and 2 crystallize in the hexagonal space group P6{sub 3}mc (No. 186) and orthorhombic space group Cmcm (No. 63), respectively. Compound 1, constructed from InO{sub 6} octahedra and HPO{sub 3} pseudo-pyramids, exhibits a rare (3,6)-connected layer structure with kgd (Kagome dual) topology. Compound 2, on the other hand, features a 3D phosphite-oxalate hybrid structure with intersecting 8- and 12-MRs channels. From a topological perspective 2 can be regarded as a (3, 5)-connected binodal net with the Schlaefli symbol (4{sup 2}.6)(4{sup 2}.6{sup 5}.8{sup 3}). Highlights: Black-Right-Pointing-Pointer Two novel indium phosphite and indium phosphite-oxalate hybrid compounds are synthesized. Black-Right-Pointing-Pointer (3, 6)-connected layer structure with kgd topology. Black-Right-Pointing-Pointer (3,5)-connected binodal net with the Schlaefli symbol (4{sup 2}.6)(4{sup 2}.6{sup 5}.8{sup 3}).

  18. Simultaneous biosynthesis of putrebactin, avaroferrin and bisucaberin by Shewanella putrefaciens and characterisation of complexes with iron(III), molybdenum(VI) or chromium(V).

    Science.gov (United States)

    Soe, Cho Zin; Telfer, Thomas J; Levina, Aviva; Lay, Peter A; Codd, Rachel

    2016-09-01

    Cultures of Shewanella putrefaciens grown in medium containing 10mM 1,4-diamino-2-butanone (DBO) as an inhibitor of ornithine decarboxylase and 10mM 1,5-diaminopentane (cadaverine) showed the simultaneous biosynthesis of the macrocyclic dihydroxamic acids: putrebactin (pbH2), avaroferrin (avH2) and bisucaberin (bsH2). The level of DBO did not completely repress the production of endogenous 1,4-diaminobutane (putrescine) as the native diamine substrate of pbH2. The relative concentration of pbH2:avH2:bsH2 was 1:2:1, which correlated with the substrate selection of putrescine:cadaverine in a ratio of 1:1. The macrocycles were characterised using LC-MS as free ligands and as 1:1 complexes with Fe(III) of the form [Fe(pb)](+), [Fe(av)](+) or [Fe(bs)](+), with labile ancillary ligands in six-coordinate complexes displaced during ESI-MS acquisition; or with Mo(VI) of the form [Mo(O)2(pb)], [Mo(O)2(av)] or [Mo(O)2(bs)]. Chromium(V) complexes of the form [CrO(pb)](+) were detected from solutions of Cr(VI) and pbH2 in DMF using X-band EPR spectroscopy. Supplementation of S. putrefaciens medium with DBO and 1,3-diaminopropane, 1,6-diaminohexane or 1,4-diamino-2(Z)-butene (Z-DBE) resulted only in the biosynthesis of pbH2. The work has identified a native system for the simultaneous biosynthesis of a suite of three macrocyclic dihydroxamic acid siderophores and highlights both the utility of precursor-directed biosynthesis for expanding the structural diversity of siderophores, and the breadth of their coordination chemistry. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Molybdenum sulfide/carbide catalysts

    Science.gov (United States)

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

    2007-05-29

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

  20. Coordination studies of 1,2-bis(diphenylphosphinoethane with di-μ-hydroxo dinuclear complexes of tungsten(IV and molybdenum(IV

    Directory of Open Access Journals (Sweden)

    Minato Makoto

    2016-01-01

    Full Text Available The new trifluoroethoxo phosphine complexes [Cp2M(η1-dppe(CF3CH2O]+ and [Cp2(CF3CH2OM(μ-dppeMCp2(CF3CH2O]2+ (M = Mo or W, Cp = η-C5H5 and dppe = Ph2PCH2CH2PPh2 have been prepared by reaction of cationic di-μ-hydroxo dinuclear complex of molybdenocene or tungstenocene [Cp2M(μ-OH2MCp2]2+ with dppe. From the 1H and 31P NMR data, the configurations of the products could be assigned. Furtheremore, X-ray crystallography was used to definitively identify one of the product [Cp2(CF3CH2OMo(μ-dppeMoCp2(CF3CH2O]2+, which crystallizes in space group P21/c(#14 with a = 12.230(5 Å, b = 11.149(5 Å, c = 28.966(7 Å, β = 101.07(3°, V = 3876(2 Å3, and Z = 2. It was ascertained that the amount of dppe added to the reaction mixture could influence the product distribution. A mechanism involving initial replacement of the hydroxo ligand by the alkoxo group followed by nucleophilic attack of the phosphine is proposed on the basis of the reaction profile.

  1. Immobilized molybdenum-thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins

    Science.gov (United States)

    Mohammadikish, M.; Masteri-Farahani, M.; Mahdavi, S.

    2014-03-01

    In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.

  2. Study of molybdenum (VI) complexation and precipitation by zirconium (IV) in strongly acid medium. Application to nuclear spent fuel dissolution; Etude de la complexation et de la precipitation du molybdene (VI) par le zirconium (IV) en milieu tres acide. Application a la dissolution du combustible nucleaire irradie

    Energy Technology Data Exchange (ETDEWEB)

    Esbelin, E

    1999-07-01

    These last years the formation of solid deposits has been observed in the dissolution workshops of the La Hague plant. A sample of the solid was withdrawn for expertise: molybdenum and zirconium are the two major components of the solid, identified as zirconium molybdate. This thesis consisted in the approach of the mechanisms in solution liable to induce precipitate formation. After a bibliographical overview on the chemistry of Mo(VI) in highly acidic solution, this system was studied by absorption spectrophotometry in perchloric medium. The implication of two major forms of Mo(VI) in a dimerization equilibrium was confirmed by this way and by {sup 95}Mo NMR. The principal parameters governing this equilibrium were identified. It is thus shown that the molybdenum dimerization reaction is exothermic. Disturbance of the Mo(VI) system in highly acidic solution by Zr(IV) was also studied. In a restricted experimental field, for which 'conventional' exploitation methodologies had to be adapted to the system, a main complex of stoichiometry 1:1 between Mo(VI) and Zr(IV) was found. The precipitation study of Mo(VI) by Zr(IV) under conditions close to those of the dissolution medium of nuclear spent fuel was undertaken. The main parameters which control precipitation kinetics were identified. The results obtained reveal that precipitation is controlled by a single macroscopic process and therefore can be described by a single equation. The solid obtained is composed of only one phase presenting a Mo:Zr non-stoichiometry when compared to the theoretical formula ZrMo{sub 2}O{sub 7}(OH){sub 2},2H{sub 2}O. At last, on the basis of the research results, a descriptive mechanism of the system is proposed in which intervenes a 1:1 intermediate complex, much more soluble than a probable 2:1 precipitation precursor. (author)

  3. Gel Fabrication of Molybdenum “Beads”

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Richard Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Cooley, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2016-11-01

    Spherical molybdenum particles or “beads” of various diameters are of interest as feedstock materials for the additive manufacture of targets and assemblies used in the production of 99Mo medical isotopes using accelerator technology. Small metallic beads or ball bearings are typically fabricated from wire; however, small molybdenum spheres cannot readily be produced in this manner. Sol-gel processes are often employed to produce small dense microspheres of metal oxides across a broad diameter range that in the case of molybdenum could be reduced and sintered to produce metallic spheres. These Sol-gel type processes were examined for forming molybdenum oxide beads; however, the molybdenum trioxide was chemically incompatible with commonly used gelation materials. As an alternative, an aqueous alginate process being assessed for the fabrication of oxide spheres for catalyst applications was employed to form molybdenum trioxide beads that were successfully reduced and sintered to produce small molybdenum spheres.

  4. High-throughput syntheses of iron phosphite open frameworks in ionic liquids

    Science.gov (United States)

    Wang, Zhixiu; Mu, Ying; Wang, Yilin; Bing, Qiming; Su, Tan; Liu, Jingyao

    2017-02-01

    Three open-framework iron phosphites: Feп5(NH4)2(HPO3)6 (1), Feп2Fe♯(NH4)(HPO3)4 (2) and Fe♯2(HPO3)3 (3) have been synthesized under ionothermal conditions. How the different synthesis parameters, such as the gel concentrations, synthetic times, reaction temperatures and solvents affect the products have been monitored by using high-throughput approaches. Within each type of experiment, relevant products have been investigated. The optimal reaction conditions are obtained from a series of experiments by high-throughput approaches. All the structures are determined by single-crystal X-ray diffraction analysis and further characterized by PXRD, TGA and FTIR analyses. Magnetic study reveals that those three compounds show interesting magnetic behavior at low temperature.

  5. Photooxidation of Trimethyl Phosphite in Nitrogen, Oxygen, and para-Hydrogen Matrixes at Low Temperatures.

    Science.gov (United States)

    Ramanathan, N; Sundararajan, K; Gopi, R; Sankaran, K

    2017-03-16

    Trimethyl phosphite (TMPhite) was photooxidized to trimethyl phosphate (TMP) in N2, O2, and para-H2 matrixes at low temperatures to correlate the conformational landscape of these two molecules. The photooxidation produced the trans (TGG)-rich conformer with respect to the ground state gauche (GGG) conformer of TMP in N2 and O2 matrixes, which has diverged from the conformational composition of freshly deposited pure TMP in the low-temperature matrixes. The enrichment of the trans conformer in preference to the gauche conformer of TMP during photooxidation is due to the TMPhite precursor, which exists exclusively in the trans conformer. Interestingly, whereas the photooxidized TMP molecule suffers site effects possibly due to the local asymmetry in N2 and O2 matrixes, in the para-H2 matrix owing to the quantum crystal nature the site effects were observed to be self-repaired.

  6. Response of Winter Wheat Grain Yield and Phosphorus Uptake to Foliar Phosphite Fertilization

    Directory of Open Access Journals (Sweden)

    Muaid S. Ali

    2014-01-01

    Full Text Available One of the major problems that potentially hinders the use of foliar fertilization as a tool to improve nutrient use efficiency is the lack of effective formulations. A phosphite based product, Nutri-phite (3% N, 8.7% P, and 5.8% K was used as model phosphite formulation for foliar application in winter wheat (Triticum aestivum L. Five field trials were established in the fall of 2009 and 2010 at Perkins, Perry, and Morrison, OK. Treatments encompassed the application of nitrogen (N at 100 or 75% of crop need and phosphorus at 100 (P 100% and 80% (P 80% sufficiency with and without Nutri-phite. Nutri-phite was applied at one and/or two stages of wheat; GS 13 to 14 and GS 49 to 53 at the rate of 433 and 148 g ha−1 P and N, respectively. Grain yield was increased by Nutri-phite treatments, especially at Morrison. Grain P concentration of plots treated with two applications of Nutri-phite ranged from 13 to 55% more than the nontreated and standard NP received plots at Perkins in 2009/10 and Perry in 2010/11. Grain P uptake was increased due to application of Nutri-phite at Perkins in 2009/10 and Morrison and Perry in 2010/11. Combined over three year-locations, Nutri-phite increased grain P concentration by 11.6%. The higher grain P concentration of plots treated with Nutri-phite compared to the other treatments clearly demonstrates its potential in improving P status of wheat grain.

  7. Simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys.

    Science.gov (United States)

    Dupraw, W A

    1972-06-01

    A simple analytical procedure is described for determining zirconium or hafnium in molybdenum-base alloys by formation of the Arsenazo III complex of zirconium or hafnium in 9 M hydrochloric acid medium. The absorbance is measured at 670 nm. Molybdenum (10 mg), titanium (1 mg), and rhenium (10 mg) have no adverse effect. No prior separation is needed. The relative standard deviation is 1.3-2.7%.

  8. The involvement of molybdenum in life.

    Science.gov (United States)

    Williams, R J P; Fraústo da Silva, J J R

    2002-03-29

    Quite extraordinarily molybdenum is an essential element in life for the uptake of nitrogen from both nitrogen gas and nitrate, yet it is a relatively rare heavy trace element. It also functions in a few extremely important oxygen-atom transfer reactions at low redox potential. This review poses the question "Why does life depend upon molybdenum?" The answer has to be based upon the availability of the element and on chemical superiority in carrying out the essential tasks. We illustrate here the peculiarities of molybdenum chemistry and how they have become part of certain enzymes. The uptake and incorporation of molybdenum are dependent on its availability, selective pumps, and carriers (chaperones), but 4.5 x 10(9) years ago molybdenum was not available when both tungsten and vanadium or even iron were possibly used in its place. While these possibilities are explored, they leave many unanswered questions concerning the selection today of molybdenum. (c)2002 Elsevier Science (USA).

  9. [Molybdenum as an air pollutant].

    Science.gov (United States)

    Lindner, R; Junker, E; Hoheiser, H

    1990-07-01

    Investigations into the reasons for the retarded growth and discolouration of a small area of a field of rape situated on the outskirts of Vienna revealed higher than normal levels of molybdenum in the soil (up to 430 micrograms/l) and in the water (up to 9.7 mg/l). The source of the pollution was traced to a neighbouring industrial plant that was emitting the metal via the chimney stack. A review of the literature on the toxic effects of molybdenum in general and as an air pollutant in particular is provided. This shows that, in contrast to animals, this effect is relatively small in humans and plants. Nevertheless, the occupation-related inhalation of the metal has been shown to be associated with pneumoconiosis and gout-like symptoms.

  10. Zirconia-molybdenum disilicide composites

    Science.gov (United States)

    Petrovic, John J.; Honnell, Richard E.

    1991-01-01

    Compositions of matter comprised of molybdenum disilicide and zirconium oxide in one of three forms: pure, partially stabilized, or fully stabilized and methods of making the compositions. The stabilized zirconia is crystallographically stabilized by mixing it with yttrium oxide, calcium oxide, cerium oxide, or magnesium oxide and it may be partially stabilized or fully stabilized depending on the amount of stabilizing agent in the mixture.

  11. Non-noble metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jun-Ling, E-mail: s070054@e.ntu.edu.sg [China-Australia Joint Research Centre for Functional Molecular Materials, School of Chemical & Material Engineering, Jiangnan University, Wuxi 214122 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Zhang, Jian-Han; Mao, Jiang-Gao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

    2016-05-15

    We reported the synthesis and crystal structures of alkali metal and alkali-earth metal phosphite, namely, CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} (1), and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO{sub 6} octahedra which are connected by HPO{sub 3} tetrahedra via corner-sharing. Alkali or alkali earth metal cations are filled in the different channels of the frameworks. Topological analysis shows that the framework of CsV{sub 2}(H{sub 3}O) (HPO{sub 3}){sub 4} (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.6"2}{sub 2}{4"2.6"6.8"2}{6"3}{6"5.8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H{sub 2} evolution and degradation of methylene blue, which shows that both compounds exhibit activity under visible-light irradiation. IR spectrum, UV–vis-NIR spectrum and thermogravimetric analysis (TGA) of compounds were also investigated. - Graphical abstract: Metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution and the degradation of methylene blue aqueous solution. - Highlights: • Two new vanadium phosphites, CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6}, are reported. • CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} feature complicated 3D framework structures with different channels. • CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} exhibit strong and broad absorptions in the visible and Near IR region. • Photocatalytic properties of CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} are investigated. • The magnetic

  12. Development of an ion-pair reversed-phase HPLC method with indirect UV detection for determination of phosphates and phosphites as impurities in sodium risedronate.

    Science.gov (United States)

    Breuzovska, Katerina; Dimitrovska, Aneta; Kitanovski, Zoran; Petrusevska, Jelena; Ribarska, Jasmina Tonic; Jolevska, Suzana Trajkovic

    2010-01-01

    A method based on RP-HPLC with indirect UV detection was developed for the determination of phosphates and phosphites as impurities in sodium risedronate. RP separation of the phosphates and phosphites was achieved by adding tetrabutylammonium hydroxide as an ion-pairing agent in the mobile phase. Potassium hydrogen phthalate was added to the mobile phase as an ionic chromophore in order to obtain high background absorption of the mobile phase. Separation was performed on a C18 column using a mixture of pH 8.2 buffer (containing 0.5 mM tetrabutylammonium hydroxide and 1 mM phthalate) and acetonitrile (95 + 5, v/v) as the mobile phase, with indirect UV detection at 248 nm. The validation of the method included determination of specificity/selectivity, linearity, LOD, LOQ, accuracy, precision, and robustness. The LOD was 0.86 microg/mL for phosphates and 0.76 microg/mL for phosphites. The LOQ was 2.60 microg/mL for phosphates and 2.29 microg/mL for phosphites. The developed method is suitable for quantitative determination of phosphates and phosphites as impurities in QC of sodium risedronate.

  13. Homoleptic coordination of arsenine C5H5As to molybdenum(0) and tungsten(0): further observations on the eta1,eta6-dilemma.

    Science.gov (United States)

    Elschenbroich, Christoph; Six, Jörg; Harms, Klaus

    2008-01-07

    By means of metal-atom ligand-vapor cocondensation (CC) hexa(eta1-arsenine)molybdenum (11) and hexa(eta1-arsenine)tungsten (12) have been prepared; in the molybdenum case, the sandwich complex bis(eta6-arsenine)molybdenum (10) has been isolated as the primary product. The structure of 12 follows from a single-crystal X-ray diffraction study. Based on the results of CC synthesis, chromium binds to arsenine in the eta6-mode exclusively, molybdenum features both options eta1 and eta6, and for tungsten only eta1 coordination is observed.

  14. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States); PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Mendoza-Sanchez, Beatriz [CRANN, Chemistry School, Trinity College Dublin, Dublin (Ireland); Fernandez, Vincent [Institut des Matériaux Jean Rouxel, 2 rue de la Houssinière, BP 32229, F-44322 Nantes Cedex 3 (France); Veenstra, Rick [PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Dukstiene, Nijole [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas (Lithuania); Roberts, Adam [Kratos Analytical Ltd, Trafford Wharf Road, Wharfside, Manchester, M17 1GP (United Kingdom); Fairley, Neal [Casa Software Ltd, Bay House, 5 Grosvenor Terrace, Teignmouth, Devon TQ14 8NE (United Kingdom)

    2015-01-30

    Highlights: • We analyzed and modeled spectral envelopes of complex molybdenum oxides. • Molybdenum oxide films of varying valence and crystallinity were synthesized. • MoO{sub 3} and MoO{sub 2} line shapes from experimental data were created. • Informed amorphous sample model (IASM) developed. • Amorphous molybdenum oxide XPS envelopes were interpreted. - Abstract: Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  15. Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue.

    Science.gov (United States)

    Yatirajam, V; Ram, J

    1973-09-01

    A simple method is described for the separation of molybdenum from titanium, zirconium, chromium, manganese, iron, cobalt, nickel, uranium and aluminium in a wide variety of samples in molybdenum concentration of 0.6-5 my/ml in 0.4-0.5N sulphuric acid. The phosphomolybdenum blue is 99.5% extracted with methyl isobutyl ketone in a single extraction. The residual molybdenum and hydrazine in the aqueous phase are oxidized with a few drops of liquid bromine and the molybdenum is quantitatively extracted with the same solvent from 1N sulphuric acid as its reddish brown thiosulphato complex. The molybdenum is stripped by ammonia-hydrogen peroxide solution. The back-extract is heated to boiling and filtered to remove the insoluble hydroxides of traces of accompanying elements. The thiosulphate in the filtrate is destroyed by boiling for 4-5 min with excess of hydrogen peroxide in slightly ammoniacal medium. The molybdenum is determined finally by cerimetry or other standard methods.

  16. In depth study of molybdenum silicon compound formation at buried interfaces

    Science.gov (United States)

    Zoethout, Erwin; Louis, Eric; Bijkerk, Fred

    2016-09-01

    Angle resolved x-ray photoelectron spectroscopy (ARXPS) has been employed to determine non-destructively the in-depth interface formation during thin film growth. Buried interfaces underneath the nanometer thick layers are probed by identifying the chemical shift of compound materials in photoelectron spectroscopy and using the angular response to quantify the compound amounts from the measured intensities. The thin interfaces in molybdenum-silicon multilayers grown at ambient temperature are investigated. This system is an example of an almost perfect 1D-system, where the interface region is only a small part of the individual layer thicknesses of 3 to 5 nm. Despite the low growth temperature, both the interfaces of this multilayer show layer thickness dependent interface formation. While the silicon-on-molybdenum interface shows a limited interface thickness of 0.4 nm of Mo5Si3, the molybdenum-on-silicon interface shows a more complex evolution. For this interface, the composition of the first 2.0 nm of deposited layer thickness is best described as a molybdenum-silicon compound layer with a molybdenum rich top and a MoSi2 bottom layer. After 2.5 nm of the deposited layer thickness, the molybdenum rich compound at the top has transformed into polycrystalline molybdenum on top of 1.8 nm MoSi2 at the interface. The formation of the 1.8 nm MoSi2 precedes the formation of polycrystalline molybdenum on top. Angle resolved x-ray photoelectron spectroscopy (ARXPS) is shown to be a good tool to study the interface phenomena beneath the nanometer thick top layers. In the case of Mo/Si multilayer mirrors, this ARXPS study shows that the compound formation at the interface accounts for the majority of the extreme ultraviolet reflectance loss.

  17. From Bola-Surfactant Templated Bimetal Phosphites to the Design of Crystalline Inorganic Mesoporous Frameworks.

    Science.gov (United States)

    Huang, Hui-Lin; Huang, Wen-Yen; Wang, Sue-Lein

    2017-04-11

    Reproducing inorganic modules in situ for pore augmentation of pure inorganic frameworks is challenging but can be a key to rational synthesis. After the first success of using monoamines of varied lengths as a template in producing a set of building blocks that led to a series of growing channels up to a 72-membered ring (72R), research continued into those building blocks to seek any new topologies from them. In this study, another type of template is reported that can control the same building blocks to repeatedly form in situ. By using long linear-chain bola-type surfactants, two new bimetal phosphites, a monoclinic phase exhibiting remarkable quasi-channels of 1.15 nm and an orthorhombic phase with 28R channels of 1.06 nm have been created. By taking them as the first members, two series of novel topologies can be devised, each having a general formula to predict the size and channel wall compositions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Nonlinear dielectric properties of planar structures based on ferroelectric betaine phosphite films

    Science.gov (United States)

    Balashova, E. V.; Krichevtsov, B. B.; Svinarev, F. B.; Yurko, E. I.

    2014-02-01

    Ferroelectric films of partly deuterated betaine phosphite are grown on NdGaO3(001) substrates with an interdigitated system of electrodes on their surfaces by evaporation at room temperature. These films have a high capacitance in the ferroelectric phase transition range. The dielectric nonlinearity of the grown structures is studied in small-signal and strong-signal response modes and in the intermediate region between these two modes by measuring the capacitance in a dc bias field, dielectric hysteresis loops, and the Fourier spectra of an output signal in the Sawyer-Tower circuit. In the phase transition range, the capacitance control ratio at a bias voltage U bias = 40 V is K ≅ 7. The dielectric nonlinearity of the structures in the paraelectric phase is described by the Landau theory of second-order phase transitions. The additional contribution to the nonlinearity in the ferroelectric phase is related to the motion of domain walls and manifests itself when the input signal amplitude is higher than U st ˜ 0.7-1.0 V. The relaxation times of domain walls are determined from an analysis of the frequency dependences of the dielectric hysteresis.

  19. Structural, thermal and electrical studies of a novel rubidium phosphite tellurate compound

    DEFF Research Database (Denmark)

    Beyribey, Didem Berceste; Hallinder, Jonathan

    2012-01-01

    Structural, thermal and electrical properties studies of rubidium phosphite tellurate, RbH(PO3H)·Te(OH)6, were performed. An endothermic peak, which reached a completion at about 315 °C accompanied with a weight loss of 4.6 wt.%, was attributed to dehydration. Four types of pellets were produced...... to room temperature, a second measurement with pellet C was carried out under the same conditions as used for pellets A and B. Pellet D, on the other hand, was heated up to 450 °C, kept at that temperature for 2 h and then cooled down to room temperature prior to the conductivity measurements....... It was observed that the conductivities of pellets A and B decreased to values of 5.2 × 10−8 S cm−1 and 6.6 × 10−7 S cm−1 at 317 °C, respectively, and an unexpected rise in the conductivity (9.89 × 10−6 S cm−1 at 317 °C) was seen with pellet C. Dehydration of RbH(PO3H)·Te(OH)6 might be responsible...

  20. Non-noble metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution

    Science.gov (United States)

    Song, Jun-Ling; Zhang, Jian-Han; Mao, Jiang-Gao

    2016-05-01

    We reported the synthesis and crystal structures of alkali metal and alkali-earth metal phosphite, namely, CsV2(H3O)(HPO3)4 (1), and Ba3V2(HPO3)6 (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO6 octahedra which are connected by HPO3 tetrahedra via corner-sharing. Alkali or alkali earth metal cations are filled in the different channels of the frameworks. Topological analysis shows that the framework of CsV2(H3O) (HPO3)4 (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.62}2{42.66.82}{63}{65.8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV2(H3O)(HPO3)4 suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H2 evolution and degradation of methylene blue, which shows that both compounds exhibit activity under visible-light irradiation. IR spectrum, UV-vis-NIR spectrum and thermogravimetric analysis (TGA) of compounds were also investigated.

  1. Price Hike in Molybdenum Industrial Chain Picked Up Speed

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    Affected by industry-wide joint production restriction,prices of molybdenum concentrate,molybdenum oxide and ferromolybdenum surged across the board.Following the average rising margin up to 1%to 2%on May 23,on May 24,prices of molybdenum concentrate and molybdenum oxide again were adjusted upward by 50 yuan per tonne,rising by 5%,which

  2. Phosphite-Thiother Ligands Derived from Carbohydrates allow the Enantioswitchable Hydrogenation of Cyclic β-Enamides by using either Rh or Ir Catalysts.

    Science.gov (United States)

    Margalef, Jèssica; Pàmies, Oscar; Diéguez, Montserrat

    2017-01-18

    Phosphite-thioether ligands with a simple modular architecture, derived from inexpensive l-(+)-tartaric acid and d-mannitol, have been for the first time successfully applied (ee values up to 99 %) in the synthesis of 2-aminotetralines and 3-aminochromanes by metal-catalyzed asymmetric hydrogenation of cyclic β-enamides. The ligands have the advantages of the robustness of the thioether/phosphite moieties and the extra control provided by the flexibility of the chiral pocket through the presence of a biaryl phosphite group and a modular carbohydrate-derived backbone. Moreover, they are solid and stable to air and they are therefore easy to handle, manipulate, and store. Usefully, both enantiomers of the hydrogenated products were obtained by simply switching from Rh to Ir. Low hydrogen pressure and environmentally friendly propylene carbonate can be used, with no loss of selectivity.

  3. Chemistry of dihydrogen complexes containing only phosphorus co-ligands

    Indian Academy of Sciences (India)

    Balaji R Jagirdar; Nisha Mathew

    2002-08-01

    A series of new dicationic dihydrogen complexes of ruthenium of the type cis-[(dppm)2Ru(2-H2)(L)][BF4]2 (dppm = Ph2PCH2PPh2; L = phosphite) have been prepared by protonating the precursor hydride complexes cis-[(dppm)2Ru(H)(L)][BF4] using HBF4$\\cdot$Et2O. The precursor hydride complexes have been obtained from trans-[(dppm)2Ru(H)(L)][BF4] (L = phosphite) via a rare acidcatalysed isomerization reaction in six coordinate species. The trans-[(dppm)2Ru(H)(L)][BF4] complexes (L = phosphine) upon protonation gave the isomerized derivatives, however, further addition of acid resulted in a five-coordinate species, [(dppm)2RuCl]+ presumably via an intermediate phosphine dihydrogen complex. The electronic as well as the steric properties of the co-ligands seem to strongly influence the structure-reactivity behaviour of this series of complexes.

  4. MOLYBDENUM

    African Journals Online (AJOL)

    electron donor), have been found to have 3:4 square pyramidal structures with the cyclopentadienyl .... The relative ratios of the cis to trans ring proton resonances gives the proportion of cis to .... relationship is not obvious by our analysis.

  5. Chain Extension and Thermal Behavior of Recycled Poly(Ethylene Terephthalate Modified by Reactive Extrusion with Triphenyl Phosphite

    Directory of Open Access Journals (Sweden)

    Qin Dan

    2016-01-01

    Full Text Available Reactive extrusion experiments of recycled PET fabrics (R-PET were carried out in a Haake torque rheometer with triphenyl phosphite (TPP and thermal behavior of modified R-PET was investigated by differential scanning calorimetry (DSC. The reaction mechanism which TPP acts as a cross-linker is verified by the experiment of phosphorus elemental analysis. DSC results show the presence of reaction residues may not modify melting temperature Tm and crystallization temperature Tc is controlled by the combined effect of molecular weight and reaction residues.

  6. Process for Functionalizing Biomass using Molybdenum Catalysts

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention concerns a process for converting biomass into useful organic building blocks for the chemical industry. The process involves the use of molybdenum catalysts of the formula Aa+a(MovXxR1yR2zR3e)a*3-, which may be readily prepared from industrial molybdenum compounds.......The present invention concerns a process for converting biomass into useful organic building blocks for the chemical industry. The process involves the use of molybdenum catalysts of the formula Aa+a(MovXxR1yR2zR3e)a*3-, which may be readily prepared from industrial molybdenum compounds....

  7. Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, Low-Carbon Nickel-Chromium-Molybdenum-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Tungsten, and Low-Carbon Nickel-Molybdenum-Chromium Alloy Plate, Sheet, and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, Low-Carbon Nickel-Chromium-Molybdenum-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Tungsten, and Low-Carbon Nickel-Molybdenum-Chromium Alloy Plate, Sheet, and Strip

  8. Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium, Low-Carbon Nickel-Molybdenum-Chromium-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, and Low-Carbon Nickel-Chromium-Molybdenum-Tungsten Alloy Rod

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium, Low-Carbon Nickel-Molybdenum-Chromium-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, and Low-Carbon Nickel-Chromium-Molybdenum-Tungsten Alloy Rod

  9. Double nucleophilic 1,2-addition of silylated dialkyl phosphites to 4-phosphono-1-aza-1,3-dienes: synthesis of gamma-phosphono-alpha-aminobisphosphonates.

    Science.gov (United States)

    Masschelein, Kurt G R; Stevens, Christian V

    2007-11-23

    gamma-Phosphono-alpha-aminobisphosphonates were synthesized from a new class of 4-phosphono-1-aza-1,3-dienes by the addition of dialkyl trimethylsilyl phosphites to these azadienes in the presence of acid. Depending on the steric demand of the group on nitrogen, double 1,2-addition or tandem 1,4-1,2-addition occurred.

  10. The Densification of Molybdenum and Molybdenum Alloy Powders Using Hot Isostatic Pressing.

    Science.gov (United States)

    1985-08-01

    TECHNICAL REPORT ARLCB-TR-85025 00 THE DENSIFICATION OF MOLYBDENUM (n AND MOLYBDENUM ALLOY POWDERS USING HOT ISOSTATIC PRESSING J. BARRANCO I. AHMAD S...ISOSTATIC PRESSING Final 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(o) . CONTRACT OR GRANT NUMBER(e) J. Barranco , I. Ahmad, S. Isserow, and R. Warenchak

  11. Well-Defined Silica Grafted Molybdenum Bis(imido) Catalysts for Imine Metathesis Reactions

    KAUST Repository

    Barman, Samir

    2017-04-06

    Novel site-isolated tetracoordinated molybdenum complexes possessing bis(imido) ligands, [(≡Si–O)2Mo(═NR)2] (R = t-Bu, 2,6-C6H3-i-Pr2), were immobilized on partially dehydroxylated silica (SiO2-200) by a rigorous surface organometallic chemistry protocol. The newly developed materials adorned with bis(imido) functional units, which were previously exploited mainly as spectator ligands on silica-supported olefin metathesis molybdenum catalysts, are found to be efficient heterogeneous catalytic systems for imine cross metathesis under mild conditions.

  12. Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger.

    Science.gov (United States)

    Fritz, J S; Topping, J J

    1971-09-01

    In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.

  13. Properties and analytical applications of the heteropolymolybdates of phosphorus, arsenic, silicon and germanium-IV Determination of phosphomolybdic and silicomolybdic acids via the molybdenum content, with phenylfluorone.

    Science.gov (United States)

    Halász, A; Polyák, K; Pungor, E

    1971-07-01

    Procedures are proposed for the determination of phosphorus and silicon in the ppM range, by extraction of phosphomolybdic and silicomolybdic acids with organic solvent, decomposition of the complex and spectrophotometric determination of its molybdenum content.

  14. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II) carbohydrate organometallic complexes

    NARCIS (Netherlands)

    Hanif, Muhammad; Meier, Samuel M; Nazarov, Alexey A; Risse, Julie; Legin, Anton; Casini, Angela; Jakupec, Michael A; Keppler, Bernhard K; Hartinger, Christian G

    2013-01-01

    The synthesis and in vitro cytotoxicity of a series of Ru(II)(arene) complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well

  15. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II) carbohydrate organometallic complexes

    NARCIS (Netherlands)

    Hanif, Muhammad; Meier, Samuel M; Nazarov, Alexey A; Risse, Julie; Legin, Anton; Casini, Angela; Jakupec, Michael A; Keppler, Bernhard K; Hartinger, Christian G

    2013-01-01

    The synthesis and in vitro cytotoxicity of a series of Ru(II)(arene) complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well

  16. Preparation of selective molybdenum concentrate from collective coppermolybdenum concentrate

    Directory of Open Access Journals (Sweden)

    N. Tusupbaev

    2016-06-01

    Full Text Available The paper considers possibilities of selective separation of the concentrate of copper and molybdenum from a collective copper-molybdenum concentrate of Aktogay deposit using regrinding and conventional flotation reagents. In the case of conventional flotoreagents, the content of molybdenum in a molybdenum concentrate was 8.0% at extraction effectiveness 83.12%. At 27.96% extraction degree of copper, it’s content in the concentrate equaled to 21.3%. After regrinding, molybdenum content in the concentrate was 24.0% at the extraction effectiveness 59.63%, and copper content in the concentrate was 21.9% at the recovery of 61.23%. Thus, the regrinding of a collective copper-molybdenum concentrate resulted in an increase in the content of molybdenum in molybdenum concentrate by 16%, and the copper concentration increased by 0.6%.

  17. Zunyi Molybdenum & Nickel Mining Enterprises Are Still in Suspension Status

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    According to the 2015 mid-year report of Tiancheng Holding,because Guizhou Province is still enforcing policy regulation&environmental; protection policy for molybdenum&nickel; mining industry,currently all molybdenum and nickel mining

  18. Reduction property of rare earth oxide doped molybdenum oxide

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rare earth oxide doped molybdenum powders were prepared by the reduction of rare earth nitrites doped MoO3. The effect of rare earth oxide on the reduction behavior of molybdenum oxide had been studied by means of Temperature Programmed Reduction (TPR), thermal analysis, X-ray diffraction. Doping rare earth oxide in the powder could lower the reduction temperature of molybdenum oxide and decrease the particle size of molybdenum. The mechanism for the effects had been discussed in this paper.

  19. Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625), Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219), and Nickel-Chromium-Molybdenum-Tungsten Alloy (UNS N06650) Rod and Bar

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625), Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219), and Nickel-Chromium-Molybdenum-Tungsten Alloy (UNS N06650) Rod and Bar

  20. Crystal structure of (NH42[FeII5(HPO36], a new open-framework phosphite

    Directory of Open Access Journals (Sweden)

    Teresa Berrocal

    2014-11-01

    Full Text Available Diammonium hexaphosphitopentaferrate(II, (NH42[Fe5(HPO36], was synthesized under mild hydrothermal conditions and autogeneous pressure, yielding twinned crystals. The crystal structure exhibits an [FeII5(HPO36]2− open framework with NH4+ groups as counter-cations. The anionic skeleton is based on (001 sheets of [FeO6] octahedra (one with point-group symmetry 3.. and one with .2. linked along [001] through [HPO3]2− oxoanions. Each sheet is constructed from 12-membered rings of edge-sharing [FeO6] octahedra, giving rise to channels with a radius of ca 3.1 Å in which the disordered NH4+ cations are located. The IR spectrum shows vibrational bands typical for phosphite and ammonium groups.

  1. Thermal study on the impurity effect on thermodynamic stability of the glacial phase in triphenyl phosphite-triphenyl phosphate system

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, Ikue [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan); Takeda, Kiyoshi [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)]. E-mail: takeda@naruto-u.ac.jp; Murata, Katsuo [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)

    2005-06-15

    To investigate the impurity effect on thermodynamic stability of the glacial phase, an apparently amorphous metastable phase observed in triphenyl phosphite (TPP), the differential scanning calorimetry (DSC) was carried out in the temperature range 120-350 K for binary mixtures between TPP and triphenyl phosphate (TPPO). Heating up from the glassy liquid, supercooled liquid phase transformed into glacial phase below the crystallization temperature for all the samples with x < 0.2, where x denotes the mole fraction of TPPO. Both transformation temperatures from liquid to glacial and from glacial to crystal increased and temperature range that glacial phase appears narrowed with the content of TPPO. The peak intensity of exothermic effect due to the transformation from liquid to glacial becomes larger whereas that from glacial to crystal reduced. The kinetic and thermodynamic stabilities were discussed for liquid and glacial phases based on the DSC results.

  2. An unknown coordination mode of the phosphite unit and a carbon-free heterocycle in two different heterobimetallic alumophosphites.

    Science.gov (United States)

    Gómora-Figueroa, A Paulina; Jancik, Vojtech; Cea-Olivares, Raymundo; Toscano, Rubén A

    2007-12-10

    The unique alumophosphite reagent LAl(SH)(mu-O)P(OEt)2 was prepared and used for the synthesis of the heterobimetallic alumophosphites [{kappa2-S,P-LAl(S)(mu-O)P(OEt)2}2Zn] and [{kappa4-S,O,O-LAl(SLi)(mu-O)P(OEt)2}2]. The first contains a rare example of two carbon-free five-membered heterocycles (Al-S-Zn-P-O) connected in a spiro fashion through the zinc atom, whereas the second possesses an unknown example of a coordination environment of a phosphite unit M-O-P(mu-OEt)2M with an uncoordinated lone electron pair on the phosphorus center.

  3. Syntheses and reactions of polymer-bound molybdenum complexes and hydrogenolyses of an alkynyl cobalt carbonyl cluster. [Co/sub 3/(CO)/sub 9/CCH/sub 2/CCH/sub 2/C(CH/sub 3/)/sub 3/; cyclopentadienyl-(tricarbonyl) hydridomolybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Frommer, J.E.

    1980-08-01

    Co/sub 3/(CO)/sub 9/CCH/sub 2/C(CH/sub 3/)/sub 3/ reacted with hydrogen in aromatic solvents to yield 3,3-dimethylbutene, 2,2-dimethylbutane, and 4,4-dimethylpentanal. First order decomposition of starting material and a hydrogen pressure dependence for the rate of appearance of total products were indicated. The hydrogenation was inhibited in the presence of carbon monoxide (CO:H/sub 2/, 3.7:3.7 atm, 60/sup 0/C), but at 85/sup 0/ under the same CO/H/sub 2/ atmosphere, aldehyde production became the predominant reaction pathway at the expense of earlier-formed olefin. Incorporation of independently added olefins in the hydrogenation suggested the intermediacy of olefin aldehyde ad alkane production. A polystyrene-attached n/sup 5/-cyclopentadienyl(tricarbonyl)-hydridomolybdenum complex was prepared and its reactions with several THF-soluble bases were investigated. Enolates of ..beta..-dicarbonyl compounds quantitatively deprotonated this complex, giving polymer-bound salts of the corresponding anion. Little change in pKa in THF was induced by binding the molybdenum hydride to the polymer. Even though the polymer-supported partners rendered the reactions heterogeneous, the systems adhered reasonably well to conventional equilibrium behavior. A polymer-bound carboxylic acid and its conjugate base also displayed essentially conventional equilibrium dynamics.

  4. Direct determination of molybdenum in seawater by adsorption cathodic stripping square-wave voltammetry.

    Science.gov (United States)

    Sun, Y C; Mierzwa, J; Lan, C R

    2000-06-30

    A reliable and very sensitive procedure for the determination of trace levels of molybdenum in seawater is proposed. The complex of molybdenum with 8-hydroxyquinoline (Oxine) is analyzed by cathodic stripping square-wave voltammetry based on the adsorption collection onto a hanging mercury drop electrode (HMDE). This procedure of molybdenum determination was found to be more favorable than differential pulse cathodic stripping voltammetry because of inherently faster scan rate and much better linearity obtained through the one-peak (instead of one-of-two peaks) calibration. The variation of polarographic peak and peak current with a pH, adsorption time, adsorption potential, and some instrumental parameters such as scan rate and pulse height were optimized. The alteration of polarographic wave and its likely mechanism are also discussed. The relationship between peak current and molybdenum concentration is linear up to 150 mug l(-1). Under the optimal analytical conditions, the determination limit of 0.5 mug l(-1) Mo was reached after 60 s of the stirred collection. The estimated detection limit is better than 0.1 mug l(-1) of Mo. The applicability of this method to analysis of seawater was assessed by the determination of molybdenum in two certified reference seawater samples (CASS-2 and NASS-2) and the comparison of the analytical results for real seawater samples (study on a vertical distribution of Mo in the seawater column) with the results obtained by Zeeman-corrected electrothermal atomization atomic absorption spectrometry (Zeeman ETAAS). A good agreement between two used methods of molybdenum determination was obtained.

  5. Chemical nature and reaction mechanisms of the molybdenum cofactor of xanthine oxidoreductase.

    Science.gov (United States)

    Okamoto, Ken; Kusano, Teruo; Nishino, Takeshi

    2013-01-01

    Xanthine oxidoreductase (XOR), a complex flavoprotein, catalyzes the metabolic reactions leading from hypoxanthine to xanthine and from xanthine to urate, and both reactions take place at the molybdenum cofactor. The enzyme is a target of drugs for therapy of gout or hyperuricemia. We review the chemical nature and reaction mechanisms of the molybdenum cofactor of XOR, focusing on molybdenum-dependent reactions of actual or potential medical importance, including nitric oxide (NO) synthesis. It is now generally accepted that XOR transfers the water-exchangeable -OH ligand of the molybdenum atom to the substrate. The hydroxyl group at OH-Mo(IV) can be replaced by urate, oxipurinol and FYX-051 derivatives and the structures of these complexes have been determined by xray crystallography under anaerobic conditions. Although formation of NO from nitrite or formation of xanthine from urate by XOR ischemically feasible, it is not yet clear whether these reactions have any physiological significance since the reactions are catalyzed at a slow rate even under anaerobic conditions.

  6. Spectrophotometric determination of molybdenum after separation by the adsorption of its trifluoroethylxanthate on naphthalene

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, M.F.; Katyal, Mohan; Puri, B.K.; Satake, Masatada

    1986-10-01

    Molybdenum reacts with potassium trifluoroethylxanthate to form a water-insoluble complex in the acid concentration range 0.1-3 M, pH 1.0-3.5. This complex is easily adsorbed on to microcrystalline naphthalene from an acetone solution and absorbs in the range 360-370 nm. Beer's law is obeyed over the concentration range 5.0-75.0 ..mu..g of molybdenum in 10 ml of chloroform solution. The molar absorptivity and Sandell sensitivity are 1.041 x 10/sup 4/ l mol/sup -1/ cm-/sup 11/ and 0.0092 ..mu..g cm/sup -2/, respectively. Ten replicate analyses of a sample solution containing 30 ..mu..g of molybdenum gave a mean absorbance of 0.325 with a relative standard deviation of 0.60%. The interferences of various ions were studied and conditions were developed for the determination of molybdenum in some alloy samples.

  7. Effect of La203 nanoparticles on properties of molybdenum powder

    Institute of Scientific and Technical Information of China (English)

    王金淑; 周美玲; 左铁镛; 聂祚仁; 张久兴; 刘娟

    2001-01-01

    The properties of La2O3-doped molybdenum powder were studied. The La2O3 nanoparticles on the surface of molybdenum powder which is produced by the reduction of La(NO3)3-doped MoO2 in hydrogen decrease the intensity of feature energy loss peak of molybdenum substrate; but increase that of peak of Mo 3d. The surface of molybdenum powder exposed to the atmosphere can be reduced because the surface is mainly covered with La2O3 nanoparticles. As a result, the capability of anti-oxidation of molybdenum is improved.

  8. Enhanced photochromism in nanostructured molybdenum trioxide films

    Science.gov (United States)

    Beydaghyan, Gisia; Doiron, Serge; Haché, Alain; Ashrit, P. V.

    2009-08-01

    We present evidence of enhancement of photochromism in nanostructured thin films of molybdenum oxide fabricated by glancing angle deposition. The strong correlation of coloration response with the internal surface area of the films provides evidence of the importance of nanostructuring on the photochromic effect and the vital role played by the availability of water in the photochromic mechanism.

  9. Exploring atomic defects in molybdenum disulphide monolayers

    KAUST Repository

    Hong, Jinhua

    2015-02-19

    Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment-theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 10 13 cm \\'2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.

  10. A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys

    Science.gov (United States)

    Dupraw, W. A.

    1972-01-01

    A simple analytical procedure is described for accurately and precisely determining the zirconium or hafnium content of molybdenum-base alloys. The procedure is based on the reaction of the reagent Arsenazo III with zirconium or hafnium in strong hydrochloric acid solution. The colored complexes of zirconium or hafnium are formed in the presence of molybdenum. Titanium or rhenium in the alloy have no adverse effect on the zirconium or hafnium complex at the following levels in the selected aliquot: Mo, 10 mg; Re, 10 mg; Ti, 1 mg. The spectrophotometric measurement of the zirconium or hafnium complex is accomplished without prior separation with a relative standard deviation of 1.3 to 2.7 percent.

  11. Multiscale structural and electronic control of molybdenum disulfide foam for highly efficient hydrogen production

    Science.gov (United States)

    Deng, Jiao; Li, Haobo; Wang, Suheng; Ding, Ding; Chen, Mingshu; Liu, Chuan; Tian, Zhongqun; Novoselov, K. S.; Ma, Chao; Deng, Dehui; Bao, Xinhe

    2017-04-01

    Hydrogen production through water splitting has been considered as a green, pure and high-efficient technique. As an important half-reaction involved, hydrogen evolution reaction is a complex electrochemical process involving liquid-solid-gas three-phase interface behaviour. Therefore, new concepts and strategies of material design are needed to smooth each pivotal step. Here we report a multiscale structural and electronic control of molybdenum disulfide foam to synergistically promote the hydrogen evolution process. The optimized three-dimensional molybdenum disulfide foam with uniform mesopores, vertically aligned two-dimensional layers and cobalt atoms doping demonstrated a high hydrogen evolution activity and stability. In addition, density functional theory calculations indicate that molybdenum disulfide with moderate cobalt doping content possesses the optimal activity. This study demonstrates the validity of multiscale control in molybdenum disulfide via overall consideration of the mass transport, and the accessibility, quantity and capability of active sites towards electrocatalytic hydrogen evolution, which may also be extended to other energy-related processes.

  12. Homogeneous liquid-liquid extraction method for the selective separation and preconcentration of ultra trace molybdenum.

    Science.gov (United States)

    Ghiasvand, A R; Shadabi, S; Mohagheghzadeh, E; Hashemi, P

    2005-05-15

    A new simple and efficient homogeneous liquid-liquid extraction method for the selective separation and preconcentration of molybdenyl ions was developed. alpha-Benzoin oxime (ABO) was investigated as a complexing ligand, and perfluorooctanoate ion (PFOA(-)) was applied as a phase-separator agent under strongly acidic conditions. Under the optimal conditions ([ABO]=2.1x10(-3)M, [PFOA(-)]=1.8x10(-2)M, [HNO(3)]=1.7M, [acetone]=11.8% (v/v)), 10mug of molybdenum in 5ml aqueous phase could be extracted quantitatively into 40mul of the sedimented phase. The maximum concentration factor was 125-fold. Thiocyanate was applied as a chromogenic reagent for the direct spectrophotometric determination of molybdenum in the sedimented phase. The reproducibility of the proposed method is at the most 2.4%. The influence of the type and concentration of acid solution, the concentration of ABO, the type and volume of the water-miscible organic solvent, the concentration of PFOA(-), and the effect of different diverse ions on the extraction and determination of molybdenum(VI) were investigated. The proposed method was applied to the extraction and determination of molybdenum(VI) in natural water, Spinach, and Lucerne samples. A satisfactory agreement exists between the results obtained by the proposed method and those reported by GF-AAS.

  13. Molybdenum-catalyzed deoxydehydration of vicinal diols

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Rytter; Lupp, Daniel; Oh, Byung Chang

    2014-01-01

    The commercially available (NH4)6Mo7O24 and other molybdenum compounds are shown to be viable substitutes for the typically employed rhenium compounds in the catalytic deoxydehydration of aliphatic diols into the corresponding alkenes. The transformation, which represents a model system for the v......The commercially available (NH4)6Mo7O24 and other molybdenum compounds are shown to be viable substitutes for the typically employed rhenium compounds in the catalytic deoxydehydration of aliphatic diols into the corresponding alkenes. The transformation, which represents a model system...... for the various hydroxyl groups found in biomass-derived carbohydrates, can be conducted in an inert solvent (dodecane), under solvent-free conditions, and in a solvent capable of dissolving biomass-derived polyols (1,5-pentanediol). The reaction is driven by the simultaneous oxidative deformylation of the diol...

  14. Application of chromatography and mass spectrometry to the characterization of cobalt, copper, manganese and molybdenum in Morinda citrifolia.

    Science.gov (United States)

    Rybak, Justyna; Ruzik, Lena

    2013-03-15

    An analytical procedure was proposed to determine the manganese species and to study the fractionation of microelements such as copper, cobalt and molybdenum in Noni juice. Morinda citrifolia is known as a noni fruit, Indian mulberry, nunaakai, dog dumpling, mengkudu, beach mulberry, vomit fruit and cheese fruit. It is a tropical plant with a long tradition of medicinal use in Polynesia and tropical parts of eastern Asia and Australia. This article covers the determination of manganese species in Noni juice and established by fractionation by size exclusion chromatography inductively coupled plasma mass spectrometry (SEC ICP MS) and next characterization of species by electrospray ionization mass spectrometry (ESI MS). Also presented the fractionation analysis of copper, cobalt and molybdenum in Noni juice sample using SEC ICP MS - juice was treated with buffer and enzymatic extraction media and analyzed. For the evaluation of the amounts of the metal fractions distinguished, the ICP MS was used off-line prior to the determination of copper, cobalt, molybdenum and manganese concentrations in the juice. It was established that elements are present in the analyzed samples in different species and their concentration is μg mL(-1) and ng mL(-1) range in fruit. The accuracy of the entire fractionation scheme and sample preparation procedures involved was verified by the performance of the recovery test. For the information about the bioavailability of these elements, in vitro bioavailability investigation was used by SEC ICP MS technique. Two step digestion model simulating gastric (pepsin digestion) and intestinal (pancreatin digestion) juices. In Noni juice, manganese is complexed from flavonoids - rutin, from dye like anthraquinone (alizarin) and glycosides - asperulosidic acid (ESI MS - characterization). The study shows that copper and molybdenum contained in Noni juice are complexed by peptides, and cobalt by organic acids (which are 3.6% of juice). Molybdenum in

  15. Deformation localization and cyclic strength in polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, O.T.; Rakshin, A.F.; Fenyuk, M.I.

    1983-06-01

    Conditions of deformation localization and its interrelation with cyclic strength in polycrystalline molybdenum were investigated. A fatigue failure of polycrystalline molybdenum after rolling and in an embrittled state reached by recrystallization annealing under cyclic bending at room temperature takes place under nonuniform distribution of microplastic strain resulting in a temperature rise in separate sections of more than 314 K. More intensive structural changes take place in molybdenum after rolling than in recrystallized state.

  16. Gigantic Copper-Molybdenum Mining Project Contract Signed in Guangdong

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>With the reserves of nearly 1,000,000 tons of copper and approximately 250,000 tons of molybdenum and a total investment of RMB 5 billion, Guangdong Fengkai Yuanzhushan copper-molybdenum mining project contract was inked on October 13, 2011. It is reported that this is China’s second largest open-cast copper molybdenum mine next only to Dexing Copper Mine.

  17. Selection of molybdenum sheet for deep drawing applications

    Energy Technology Data Exchange (ETDEWEB)

    Salt, P.J. (Marconi Elliott Avionic Systems Ltd., Borehamwood (UK))

    1982-06-01

    Finished tubes are considered to be an extreme example of the art of deep drawing thin molybdenum sheet. This paper describes an investigation into the manufacture of unalloyed molybdenum tube from sheet material 0.5 mm thick. Metallographic examination of different starting materials revealed the most suitable molybdenum sheet materials for this application and so avoid the conditions that bring about undesirable structures or properties.

  18. Scientific Opinion on Dietary Reference Values for molybdenum

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA

    2013-08-01

    Full Text Available Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA derived Dietary Reference Values (DRVs for molybdenum. Molybdenum is efficiently and rapidly absorbed at a wide range of intakes, and the body is able to maintain homeostasis through the regulation of excretion via the urine. Molybdenum deficiency in otherwise healthy humans has not been observed and there are no biomarkers of molybdenum status. Various metabolic balance studies have been performed to establish molybdenum requirements. However, only one balance study, which was performed with a constant diet and under controlled conditions in adult men, was considered to be of sufficient duration. In this small study, balance was reported to be near zero when molybdenum intakes were 22 µg/day. Biochemical changes or symptoms suggestive of molybdenum deficiency were not observed, and it is possible that humans may be able to achieve molybdenum balance at even lower intakes. Data on molybdenum intakes and health outcomes were unavailable for the setting of DRVs for molybdenum. As the evidence required to derive an Average Requirement and a Population Reference Intake was considered insufficient, an Adequate Intake (AI is proposed. Observed molybdenum intakes from mixed diets in Europe were taken into consideration in setting this value. An AI of 65 µg/day is proposed for adults; a figure that is based on molybdenum intakes at the lower end of the wide range of observed intakes. It is suggested that the adult AI also applies to pregnant and lactating women. An AI is also proposed for infants from seven months and for children based on extrapolation from the adult AI using isometric scaling and the reference body weights of the respective age groups.

  19. Biomass as biosorbent for molybdenum ions

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Mitiko; Santos, Jacinete L. dos; Damasceno, Marcos O.; Egute, Nayara dos S.; Moraes, Adeniane A.N.; Santos, Bruno Z., E-mail: myamaura@ipen.br, E-mail: jlsantos@ipen.br, E-mail: molidam@ipen.br, E-mail: nayara.egute@usp.br, E-mail: adenianemrs@ig.com.br, E-mail: bzsantos@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Biosorbents have been focused as renewable materials of low cost, and have been used for metal removal from the wastewater by adsorption phenomenon. Biosorbents are prepared of biomass, whose reactive sites in its chemical structure have affinity to bind to metal ions. In this work, performance of corn husk, sugarcane bagasse, coir, banana peel, fish scale, chitin and chitosan as biosorbents of molybdenum (VI) ions in aqueous medium was evaluated. The adsorption experiments were investigated in a batch system varying the pH solution from 0.5 to 12 and the contact time between the phases from 2 min to 70 min. {sup 99}Mo radioisotope was used as radioactive tracer for analysis of molybdenum ions by gamma spectroscopy using a HPGe detector. Results revealed that acidity of the solution favored the adsorption of Mo (VI) ions on the all biosorbents. Adsorption values higher than 85% were found on sugarcane bagasse, coir, corn husk, chitin and chitosan at pH 2.0. Only the chitosan was dissolved at pH 0.5 and a gel was formed. The models of pseudo-second order and external film diffusion described the kinetics of adsorption of Mo ions on the coir. This work showed that the studied biomass has high potential to be used as biosorbent of molybdenum ions from acidic wastewater, and the kinetics of Mo adsorption on the coir suggested high-affinity adsorption governed by chemisorption. (author)

  20. Syntheses Characterization of Chloro-cyclopentadienyltricarbonyl-molybdenum with

    Institute of Scientific and Technical Information of China (English)

    ZHANG; YouMing

    2001-01-01

    Organotransition metal complex have been extensively used as homogeneous catalysts in organic reactions and much effort has been paid to improve their activity and selectively. Cyclodextrins have been studied as a model of enzyme for selective catalysis. However, so far there are only a few reports on the inclusion compounds of organometallic complexes with cyclodextrins. Breslow et al.repored high acylation rates for β-CD using ferrocene derivatives and assumed β-CD substrate complexes as intermediate [1]..larad et al reported the preparation and propertics of cyclodextrin-ferrocen inclusion compounds as the first example of cyclodextrin inclusion compounds of organotransition metal complexes[2]. Song Le-Xin et al reported the supramolecular inclusion compound of β-cyclodextrin with cyclopentadieny-tricarbonylmanganese [3] .To our knowledge, there are no reports of inclusion compounds of β-CD with molybdenum organometallic complexes. In the present work we described the preparation and properties of the supramolecular of CpMo(CO)3Cl with β-CD in details.  ……

  1. Extraction and Separation of Molybdenum by Using Homogeneous Liquid-Liquid Microextraction via Flotation Assistance

    OpenAIRE

    Rezaee, Mohammad; Mozaffari,Maryam; Haddadi,Hedayat; Pourjavid,Mohammad R.; SEMNANI, Abolfazl

    2015-01-01

    Homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA) was investigated for the extraction of molybdenum from the water samples. Alizarin Red S and cetyl trimethylammonium bromide (CTAB) were used as a complexing ligand and ion-pairing reagent, respectively. The enriched analyte in the floated organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). In this work, low density organic solvent was used and no centrifugation was required in thi...

  2. Molybdenum(VI) Oxosulfato Complexes in MoO3–K2S2O7–K2SO4 Molten Mixtures: Stoichiometry, Vibrational Properties, and Molecular Structures

    DEFF Research Database (Denmark)

    Kalampounias, Angelos G.; Tsilomelekis, George; Berg, Rolf W.

    2012-01-01

    configuration as a core. The stoichiometry of the dissolution reaction MoO3 + nS2O72– → C2n– was inferred by exploiting the Raman band intensities, and it was found that n = 1. Therefore, depending on the MoO3 content, monomeric MoO2(SO4)22– and/or associated [MoO2(SO4)2]m2m– complexes are formed in the binary...

  3. The (Calix[4]arene)chloromolybdate(IV) anion [MoCl(Calix)](-): a convenient entry into molybdenum Calix[4]arene chemistry.

    Science.gov (United States)

    Radius, Udo; Attner, J

    2004-12-27

    The complex (HNEt(3))[MoCl(NCMe)(Calix)] (1), prepared from the reaction of [MoCl(4)(NCMe)(2)] with p-tert-butylcalix[4]arene, H(4)Calix, in the presence of triethylamine, has been used as a source of the d(2)-[Mo(NCMe)(Calix)] fragment. Complex 1 is readily oxidized with PhICl(2) to afford the molybdenum(VI) dichloro complex [MoCl(2)(Calix)] (2). Both complexes are a convenient entry point into molybdenum(VI) and molybdenum(IV) calixarene chemistry. The reaction of 1 with trimethylphosphine and pyridine in the presence of catalytic amounts [Ag(OTf)] led to the formation of neutral d(2) complexes [Mo(PMe(3))(NCMe)(Calix)] (3) and [Mo(NC(5)H(5))(NCMe)(Calix)] (4). The role of the silver salt in the reaction mixture is presumably the oxidation of the chloromolybdate anion of 1 to give a reactive molybdenum(V) species. The same reactions can also be initiated with ferrocenium cations such as [Cp(2)Fe](BF(4)). Without the presence of coordinating ligands, the dimeric complex [[Mo(NCMe)(Calix)](2)] (5) was isolated. The reaction of 1 with Ph(2)CN(2) led to the formation of a metallahydrazone complex [Mo(N(2)CPh(2))(NCMe)(Calix)] (6), in which the diphenyldiazomethane has been formally reduced by two electrons. Molybdenum(VI) complexes were also obtained from reaction of 1 with azobenzene and sodium azide in the presence of catalytic amounts of silver salt. The reaction with azobenzene led under cleavage of the nitrogen nitrogen bond to an imido complex [Mo(NPh)(NCMe)(Calix)] (7), whereas the reaction with sodium azide afforded the mononuclear molybdenum(VI) nitrido complex (HNEt(3))[MoN(Calix)] (8).

  4. Spectrophotometric determination of molybdenum with Alizarin Red S in the presence of poly(sulfonylpiperidinylmethylene hydroxide).

    Science.gov (United States)

    Alkan, Mahir; Kharun, Myroslava; Chmilenko, Fedor

    2003-03-01

    The present work describes a selective and rapid method for the determination of molybdenum with Alizarin Red S (ARS) in the presence of a water soluble polymer, poly(sulfonylpiperidinylmethylene hydroxide) (PSPMH). The ARS modified by PSPMH reacts with molybdenum(VI) in the solutions of pH 3.4-4.0 to produce a red complex. The composition of the complex is 1:4:1 mol ratio of Mo(VI): ARS:PSPMH. The complex obeys Beer's law from 0.05 to 5.50 mug ml(-1) with an optimum range. The molar absorptivity is 2.1x10(4) l mol(-1) cm(-1) at 500 nm. The interference effects of the foreign cations have been examined and it has been determined that only Cu(II), Al(III) and Fe(III) have to be masked by EDTA and tungsten can be tolerated till 4-fold of molybdenum in case of masking by citrate. The method has been applied to the determination of geological samples without solvent extraction or separation steps.

  5. Phosphite protects Fagus sylvatica seedlings towards Phytophthora plurivora via local toxicity, priming and facilitation of pathogen recognition.

    Science.gov (United States)

    Dalio, Ronaldo J D; Fleischmann, Frank; Humez, Martina; Osswald, Wolfgang

    2014-01-01

    Phytophthora plurivora causes severe damage on Fagus sylvatica and is responsible for the extensive decline of European Beech throughout Europe. Unfortunately, no effective treatment against this disease is available. Phosphite (Phi) is known to protect plants against Phytophthora species; however, its mode of action towards P. plurivora is still unknown. To discover the effect of Phi on root infection, leaves were sprayed with Phi and roots were subsequently inoculated with P. plurivora zoospores. Seedling physiology, defense responses, colonization of root tissue by the pathogen and mortality were monitored. Additionally the Phi concentration in roots was quantified. Finally, the effect of Phi on mycelial growth and zoospore formation was recorded. Phi treatment was remarkably efficient in protecting beech against P. plurivora; all Phi treated plants survived infection. Phi treated and infected seedlings showed a strong up-regulation of several defense genes in jasmonate, salicylic acid and ethylene pathways. Moreover, all physiological parameters measured were comparable to control plants. The local Phi concentration detected in roots was high enough to inhibit pathogen growth. Phi treatment alone did not harm seedling physiology or induce defense responses. The up-regulation of defense genes could be explained either by priming or by facilitation of pathogen recognition of the host.

  6. Study of Antiherpetic Efficiency of Phosphite of Acycloguanosine Ableto Over come the Barrier of Resistance to Acyclovir

    Science.gov (United States)

    Andronova, V. L.; Jasko, M.V.; Kukhanova, M.K.; Galegov, G.A.; Skoblov, Yr.S.; Kochetkov, S.N.

    2016-01-01

    As has been shown previously, phosphite of acycloguanosine (Hp-ACG) exhibits equal efficacy against ACV-sensitive and ACV-resistant HSV-1 strains in cell culture. Intraperitoneal administration of Hp-ACG to model mice with herpetic encephalitis caused by HSV-1 infection was shown to be effective in protecting against death. In the present work, we continue the study of the antiviral efficiency of Hp-ACG against HSV administered non-invasively; namely in vivo, orally and in the form of ointment formulations. It has been first shown that oral administration of Hp-ACG twice daily for five days prevents systemic infection in mice caused by HSV-1. Mortality in the control group of animals was 57%. Administration of Hp-ACG at doses of 600, 800 and 1,000 mg/kg per day significantly increased the survival and median day of death of the animals compared to the placebo-treated control group. A comparative evaluation of the therapeutic efficacy parameters of polyethylene glycol-based ACV ointment and Hp-ACG ointment was carried out after a 5-day course in the model of an experimental cutaneous infection of HSV-1 in guinea pigs. It was found that Hp-ACG has a significant therapeutic effect resulting in a statistically significant reduction in the lesion’s surface area and the amount of vesicular structures. The exhibited therapeutic effect of 10% Hp-ACG in ointment form compares well with that of 5% ACG ointment. PMID:27099786

  7. Small- and strong-signal dielectric response in a single-crystal film of partially deuterated betaine phosphite

    Science.gov (United States)

    Balashova, E. V.; Krichevtsov, B. B.; Lemanov, V. V.

    2011-06-01

    Poly- and single-crystal films of betaine phosphite deuterated to ˜20% have been grown by evaporation on NdGaO3 (001) substrates with a preliminarily deposited planar interdigital structure of electrodes. The small-signal dielectric response in the 0.1-100.0-kHz frequency range has revealed a strong anomaly in capacitance upon the transition of the films to the ferroelectric state. Application of a bias field brings about suppression and a slight shift of the dielectric anomaly toward higher temperatures. The strong-signal dielectric response has been studied by the Sawyer-Tower method over the frequency range 0.06-3.00 kHz both in the para- and ferroelectric phases. In contrast to the case of a plane-parallel capacitor, in the planar structure studied, the dielectric hysteresis loops exhibit a very small coercivity at low frequencies, which grows with increasing frequency. This difference should be assigned to different domain structures formed in a planeparallel capacitor and in a planar structure in a saturating field. The growth of hysteresis with increasing frequency in a planar structure is considered to be associated with the domain wall motion.

  8. The response of growth and patulin production of postharvest pathogen Penicillium expansum to exogenous potassium phosphite treatment.

    Science.gov (United States)

    Lai, Tongfei; Wang, Ying; Fan, Yaya; Zhou, Yingying; Bao, Ying; Zhou, Ting

    2017-03-06

    In this study, the effects of exogenous potassium phosphite (Phi) on growth and patulin production of postharvest pathogen Penicillium expansum were assessed. The results indicated that P. expansum under 5mmol/L Phi stress presented obvious development retardation, yield reduction of patulin and lower infectivity to apple fruit. Meanwhile, expression analysis of 15 genes related to patulin biosynthesis suggested that Phi mainly affected the early steps of patulin synthetic route at transcriptional level. Furthermore, a global view of proteome and transcriptome alteration of P. expansum spores during 6h of Phi stress was evaluated by iTRAQ (isobaric tags for relative and absolute quantitation) and RNA-seq (RNA sequencing) approaches. A total of 582 differentially expressed proteins (DEPs) and 177 differentially expressed genes (DEGs) were acquired, most of which participated in carbohydrate metabolism, amino acid metabolism, lipid metabolism, genetic information processing and biosynthesis of secondary metabolites. Finally, 39 overlapped candidates were screened out through correlational analysis between iTRAQ and RNA-seq datasets. These findings will afford more precise and directional clues to explore the inhibitory mechanism of Phi on growth and patulin biosynthesis of P. expansum, and be beneficial to develop effective controlling approaches based on Phi.

  9. Isotopic age dating of the alkaline intrusive complex and its related molybdenum polymetallic deposit at Hekanzi, western Liaoning Province%辽西河坎子碱性侵入杂岩体及钼多金属矿床同位素年代学研究

    Institute of Scientific and Technical Information of China (English)

    刘勇; 聂凤军; 方俊钦

    2012-01-01

    The newly discovered Hekanzi deposit is a medium-size porphyry molybdenum deposit in western Liaoning Province. Intrusive complexes are widely distributed in the study area, with the Mesozoic alkaline and calc-alka-line rocks being the most developed alkaline rocks. They intruded into the Precambrian and Paleozoic volcanic-sedimentary rocks in the forms of batholiths, stocks, and dykes. Alkaline intrusive rocks are mainly miascite, alkaline syenite and alkaline diabase. The calc-alkaline rocks are mainly granite porphyry, granodiorite, biotite granite and K-feldspar granite. Isotopic ages of the Hekanzi alkaline granite and its related Mo polymetallic deposit have been determined. The rock-forming age of the biotite-orthoclase granite is (235.3 ± 1.0) Ma with MSWD value of 0.68. Re-Os isotopic data of six molybdenite separates define a correlation line corresponding to an age of (224.0 ?1.3) Ma with MSWD value of 0.72. The metallic minerals in the ore are pyrite, chalcopy-rite, molybdenite, pyrrhotite, marcasite and a little scheetine. Gangue minerals are mainly calcite, fluorite, garnet, serpentine, peridotite, dolomite, feldspar, plagioclase and quartz. The NE-trending, NS-trending and NW-trending fault zones are widely distributed in the alkaline intrusive complex and its related molybdenum polymetallic deposit at Hekanzi.%对辽西河坎子地区与碱性杂岩体相关的钼多金属矿床进行了同位素年代学研究.所获黑云母正长花岗岩锆石LA-ICP-MS U-Pb同位素加权平均年龄为(235.3±1.0) Ma,MSWD值为0.68;河坎子钼多金属矿床内辉钼矿的Re-Os同位素等时线年龄为(224.0±1.3) Ma,MSWD值为0.72.碱性杂岩体与相关的钼多金属矿床具有密切的空间关系,两者的形成时间亦比较接近,据此可推测,河坎子碱性杂岩体与相关的钼多金属矿床均为印支期构造-岩浆作用及流体活动的产物.印支期内频繁的岩浆-热液活动为该地区内钼、铜、金多金属元素的活

  10. The LaH(PO sub 3 ) sub 2. 3H sub 2 O crystal structure; comparison with crystal structures of other phosphites acid compounds. Structure cristalline de LaH(PO sub 3 H) sub 2. 3H sub 2 O. Comparaison avec les autres phosphites acides

    Energy Technology Data Exchange (ETDEWEB)

    Loukili, M. (Ecole Superieure de Technologie, Fes (MA)); Rafiq, M.; Durand, J. (Faculte des Sciences, Fes (MA)); Cot, L. (Ecole Nationale Superieure de Chimie, 34 - Montpellier (FR))

    1991-10-01

    The end value R = 0.032 for the reliability factor is obtained for the 1018 considered, for absorption corrected independent reflections. All the atoms of the formula are located except the hydrogen atoms of the water molecule. The comparison of the stereochemistry with the other phosphite acid anions shows the existence of three types of arrangement anions, the Ln{sup 3+} cation is eight coordinated by seven oxygen atoms of phophite anions and one oxygen of one water molecule.

  11. Purification of molybdenum-99, obtained from uranium-235 fission, employing the resin Chelex-100

    CERN Document Server

    Lavinas, T

    1998-01-01

    The present work has the purpose of studying the purification of sup 9 sup 9 Mo employing the chelating resin Chelex-100 (Bio-Rad), due to the high distribution coefficient (10 sup 4) of the molybdenum when compared to the impurities. This fact is based on the complexation of Mo with thiocyanate ions producing a stable complex which is retained by the nitrilodiacetate groups present in the Chelex-100. Prior to the purification of sup 9 sup 9 Mo , the formation and stability of the Mo-SCN complex in different conditions were studied. The spectrophotometric studies showed the optimum conditions to obtain a stable complex: KI + Na sub 2 SO sub 3 solution was the more effective reducing agent; when in 6M sulfuric medium the complexation was faster and 6M potassium thiocyanate (complexing agent) guaranteed that all reduced molybdenum was complexed. Both the retention of Mo-SCN complex by the Chelex-100 and the elution of sup 9 sup 9 Mo, showed satisfactory, (99.6 +- 0,5)% and (96.8 +-2)% respectively, which confir...

  12. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    Science.gov (United States)

    Lowden, Richard A.

    1994-01-01

    A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

  13. REDUCTION AND CONSOLIDATION OF SUPERIOR QUALITY MOLYBDENUM ALLOYS

    Science.gov (United States)

    diameter bomb. Techniques were developed for the electron beam melting of hydrogen-reduced molybdenum powder. Although this material contains low... beam melting of the thermitically-reduced molybdenum presented difficulties; primarily because of the melting configuration. The use of a remote...interstitial elements, it exhibited severe grain boundary brittleness. Physical properties of these single crystals are being determined. The electron

  14. Molybdenum limitation of asymbiotic nitrogen fixation in tropical forest soils

    Science.gov (United States)

    Barron, Alexander R.; Wurzburger, Nina; Bellenger, Jean Phillipe; Wright, S. Joseph; Kraepiel, Anne M. L.; Hedin, Lars O.

    2009-01-01

    Nitrogen fixation, the biological conversion of di-nitrogen to plant-available ammonium, is the primary natural input of nitrogen to ecosystems, and influences plant growth and carbon exchange at local to global scales. The role of this process in tropical forests is of particular concern, as these ecosystems harbour abundant nitrogen-fixing organisms and represent one third of terrestrial primary production. Here we show that the micronutrient molybdenum, a cofactor in the nitrogen-fixing enzyme nitrogenase, limits nitrogen fixation by free-living heterotrophic bacteria in soils of lowland Panamanian forests. We measured the fixation response to long-term nutrient manipulations in intact forests, and to short-term manipulations in soil microcosms. Nitrogen fixation increased sharply in treatments of molybdenum alone, in micronutrient treatments that included molybdenum by design and in treatments with commercial phosphorus fertilizer, in which molybdenum was a `hidden' contaminant. Fixation did not respond to additions of phosphorus that were not contaminated by molybdenum. Our findings show that molybdenum alone can limit asymbiotic nitrogen fixation in tropical forests and raise new questions about the role of molybdenum and phosphorus in the tropical nitrogen cycle. We suggest that molybdenum limitation may be common in highly weathered acidic soils, and may constrain the ability of some forests to acquire new nitrogen in response to CO2 fertilization.

  15. Structural state of native molybdenum in the lunar regolith

    Science.gov (United States)

    Mokhov, A. V.; Gornostaeva, T. A.; Kartashov, P. M.; Bogatikov, O. A.; Sakharov, O. A.; Trubkin, N. V.

    2016-11-01

    The structural state was determined for zero-valence molybdenum in the lunar regolith. The body- and face-centered molybdenum forms (BCC and FCC, respectively) were identified. Disruption of the structure down to complete amorphization was noted. This might be caused by the long-term influence of the solar wind.

  16. Cationic and Neutral Cp*M(NO)(κ(2)-Ph2PCH2CH2PPh2) Complexes of Molybdenum and Tungsten: Lewis-Acid-Induced Intramolecular C-H Activation.

    Science.gov (United States)

    Handford, Rex C; Wakeham, Russell J; Patrick, Brian O; Legzdins, Peter

    2017-03-20

    Treatment of CH2Cl2 solutions of Cp*M(NO)Cl2 (Cp* = η(5)-C5(CH3)5; M = Mo, W) first with 2 equiv of AgSbF6 in the presence of PhCN and then with 1 equiv of Ph2PCH2CH2PPh2 affords the yellow-orange salts [Cp*M(NO)(PhCN)(κ(2)-Ph2PCH2CH2PPh2)](SbF6)2 in good yields (M = Mo, W). Reduction of [Cp*M(NO)(PhCN)(κ(2)-Ph2PCH2CH2PPh2)](SbF6)2 with 2 equiv of Cp2Co in C6H6 at 80 °C produces the corresponding 18e neutral compounds, Cp*M(NO)(κ(2)-Ph2PCH2CH2PPh2) which have been isolated as analytically pure orange-red solids. The addition of 1 equiv of the Lewis acid, Sc(OTf)3, to solutions of Cp*M(NO)(κ(2)-Ph2PCH2CH2PPh2) at room temperature results in the immediate formation of thermally stable Cp*M(NO→Sc(OTf)3)(H)(κ(3)-(C6H4)PhPCH2CH2PPh2) complexes in which one of the phenyl substituents of the Ph2PCH2CH2PPh2 ligands has undergone intramolecular orthometalation. In a similar manner, addition of BF3 produces the analogous Cp*M(NO→BF3)(H)(κ(3)-(C6H4)PhPCH2CH2PPh2) complexes. In contrast, B(C6F5)3 forms the 1:1 Lewis acid-base adducts, Cp*M(NO→B(C6F5)3)(κ(2)-Ph2PCH2CH2PPh2) in CH2Cl2 at room temperature. Upon warming to 80 °C, Cp*Mo(NO→B(C6F5)3)(κ(2)-Ph2PCH2CH2PPh2) converts cleanly to the orthometalated product Cp*Mo(NO→B(C6F5)3)(H)(κ(3)-(C6H4)PhPCH2CH2PPh2), but Cp*W(NO→B(C6F5)3)(κ(2)-Ph2PCH2CH2PPh2) generates a mixture of products whose identities remain to be ascertained. Attempts to extend this chemistry to include related Ph2PCH2PPh2 compounds have had only limited success. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

  17. Improvement of copper-molybdenum ore beneficiation using a combined flotation and biohydrometallurgy method

    Institute of Scientific and Technical Information of China (English)

    Irina Pestryak; Valery Morozov; Jamsranjav Baatarhuu

    2013-01-01

    The authors present the results of analysis of material composition and experimental investigations of acid and biohydrometallurgical leaching of middlings on grain size,pH level,leaching process duration,temperature and slurry density.The rational parameters of flotation and acid-bacterial leaching of middlings providing an efficient release of valuable components from mineral complexes and recovery to flotation concentrate and leaching solution have been determined.A combined flowsheet and a beneficiation process for bulk flotation middlings of copper-molybdenum ore have been suggested,which include middlings grinding,sulfide minerals flotation,bacterial leaching of sulfide flotation tailings,liquid-phase extraction of dissolved copper and electrolysis of re-extraction eluates.The suggested combined method of cleaning of middlings of copper-molybdenum ores beneficiation provides the total copper recovery increase by 0.8% with a reduction of the cost price of saleable material by 0.5%.

  18. Preparation of copper-coated fine molybdenum powders with electroless technique

    Institute of Scientific and Technical Information of China (English)

    WANG Guang-jun; WANG De-zhi; ZHOU Jie; WU Zhuang-zhi

    2009-01-01

    The molybdenum powders with average particle size of 3 μm were coated with copper by electroless plating. The influence of pretreatment, solution composition and plating conditions on electroless copper plating was studied. The copper-coated molybdenum powders were examined by SEM and XRD. Results indicate that a series of optimization methods is used to add activated sites before electroless copper plating. Taking TEA and EDTA as chief and assistant complex agents respectively, 2,2'-bipyridyl and PEG as double stabilizers, the Mo powders are coated with copper successfully with little Cu2O contained, at the same time, Mo-Cu composite powders with copper content of 15 - 85 wt% can be obtained. The optimal values of pH, temperature and HCHO concentration are 12- 13, 60-65 ℃ and 22-26 mL/L, respectively.

  19. Kinetics of Molybdenum Reduction to Molybdenum Blue by Bacillus sp. Strain A.rzi

    Directory of Open Access Journals (Sweden)

    A. R. Othman

    2013-01-01

    Full Text Available Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v glucose, 50 mM molybdate, between 28 and 30°C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong’s constants pmax, Ks, Sm, and n was 5.88 μmole Mo-blue hr−1, 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.

  20. Selective laser sintering mechanism of polymer-coated molybdenum powder

    Institute of Scientific and Technical Information of China (English)

    BAI Pei-kang; WANG Wen-feng

    2007-01-01

    A type of polymer-coated molybdenum powder used in selective laser sintering technology was prepared by coating polymer on molybdenum particles and frozen grinding techniques, with the maximum particle diameter of 71 μm. The laser sintering experiments of polymer-coated molybdenum powder were conducted by using the self-developed selective laser sintering machine (HLRP-350I). The method of microscopic analysis was used to investigate the dynamic laser sintering process of polymer-coated molybdenum powder. Based on the study, the laser sintering mechanisms of polymer-coated molybdenum powder were presented. It is found that the mechanism is viscous flow when the laser sintering temperature is between 100 ℃ and 160 ℃, which can be described by a two-sphere model; and the mechanism is melting /solidification when the temperature is above 160 ℃.

  1. Hot rolling of thick uranium molybdenum alloys

    Science.gov (United States)

    DeMint, Amy L.; Gooch, Jack G.

    2015-11-17

    Disclosed herein are processes for hot rolling billets of uranium that have been alloyed with about ten weight percent molybdenum to produce cold-rollable sheets that are about one hundred mils thick. In certain embodiments, the billets have a thickness of about 7/8 inch or greater. Disclosed processes typically involve a rolling schedule that includes a light rolling pass and at least one medium rolling pass. Processes may also include reheating the rolling stock and using one or more heavy rolling passes, and may include an annealing step.

  2. Behaviour of helium after implantation in molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Viaud, C. [Commissariat a l' Energie Atomique (CEA), Cadarache (France)], E-mail: viaud@dircad.cea.fr; Maillard, S.; Carlot, G.; Valot, C. [Commissariat a l' Energie Atomique (CEA), Cadarache (France); Gilabert, E. [Chimie Nucleaire Analytique and Bio-environnementale (CNAB), Gradignan (France); Sauvage, T. [CEMHTI-CNRS, Orleans (France); Peaucelle, C.; Moncoffre, N. [Institut de Physique Nucleaire de Lyon (IPNL), Lyon (France)

    2009-03-31

    This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature.

  3. Molybdenum oxide nanocubes: Synthesis and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai -600025 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600025 (India)

    2015-06-24

    Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO{sub 3} nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO{sub 3} has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO{sub 3} nanoparticles. DRS-UV analysis shows that MoO{sub 3} has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

  4. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

  5. Molybdenum protective coatings adhesion to steel substrate

    Science.gov (United States)

    Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.; Teplouhov, A. A.; Tyukin, A. V.; Tkachenko, E. A.

    2017-06-01

    Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings’ forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings’ durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary «steel-coating» systems.

  6. Molybdenum oxide nanocubes: Synthesis and characterizations

    Science.gov (United States)

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Stephen, A.; Narayanan, V.

    2015-06-01

    Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO3 nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO3 has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO3 nanoparticles. DRS-UV analysis shows that MoO3 has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

  7. A New Convenient Method for the Resolution of 1, 1'-Binaphthalene-2, 2'-diol Via a Phosphite Using (-)-Menthol as Resolving Agent

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    (-)-Menthol reacts with phosphorus trichloride to afford menthyl phosphorodichloridite 2,which further reacts with racemic 1, 1'-binaphthalene-2, 2'-diol to give phosphite (±)-3 in the presence of triethylamine. +(±)-3 can be easily separated by fractional crystallization to form the crystal (+)-(S)-3 and the mother liquor (-)-(R)-3. Then both the crystal and the mother liquor are treated with AcOH-H20 to obtain enantiomeric pure (-)-(S)-1 and (+)-(R)-1 respectively, with enantiomeric excess up to 99.7%.

  8. The effect of an additional phosphite stabilizer on the properties of radiation cross-linked vitamin E blends of UHMWPE.

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew; Yabannavar, Pooja; Muratoglu, Orhun K

    2014-06-01

    Antioxidant stabilization of radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) has been introduced to improve the oxidative stability of total joint implant bearing surfaces. Blending of an antioxidant with UHMWPE resin powder followed by consolidation and radiation cross-linking has been cleared by the FDA for use in both total hips and total knees for designs incorporating two antioxidants, namely vitamin E and Covernox™ (a medical grade version of Irganox™ 1010). The antioxidants in the polymer are expected to protect the polymer during consolidation, during radiation cross-linking, on the shelf before implantation, and in vivo after implantation. To maximize the protection of the polymer afforded by the antioxidant in vivo, a novel approach may be the use of multiple antioxidants, especially to protect the primary antioxidant for a longer period of time. We hypothesized that the addition of a phosphite stabilizer (Irgafos 168™) commonly used in conjunction with hindered phenolic antioxidants in polymer processing could improve the oxidative stability of radiation cross-linked blends of vitamin E. To test our hypothesis, we prepared UHMWPE blends with 0.05 wt% Irgafos and 0.05 wt% vitamin E and compared its cross-link density, wear resistance, tensile properties, and impact strength to control blends containing only vitamin E. Our hypothesis was not supported; the cross-link density of UHMWPE was significantly decreased by the additive without additional benefit to oxidative stability. To our knowledge, this was the first attempt at using multiple stabilizers in medical grade UHMWPE.

  9. Climax-Type Porphyry Molybdenum Deposits

    Science.gov (United States)

    Ludington, Steve; Plumlee, Geoffrey S.

    2009-01-01

    Climax-type porphyry molybdenum deposits, as defined here, are extremely rare; thirteen deposits are known, all in western North America and ranging in age from Late Cretaceous to mainly Tertiary. They are consistently found in a postsubduction, extensional tectonic setting and are invariably associated with A-type granites that formed after peak activity of a magmatic cycle. The deposits consist of ore shells of quartz-molybdenite stockwork veins that lie above and surrounding the apices of cupola-like, highly evolved, calc-alkaline granite and subvolcanic rhyolite-porphyry bodies. These plutons are invariably enriched in fluorine (commonly >1 percent), rubidium (commonly >500 parts per million), and niobium-tantalum (Nb commonly >50 parts per million). The deposits are relatively high grade (typically 0.1-0.3 percent Mo) and may be very large (typically 100-1,000 million tons). Molybdenum, as MoS2, is the primary commodity in all known deposits. The effect on surface-water quality owing to natural influx of water or sediment from a Climax-type mineralized area can extend many kilometers downstream from the mineralized area. Waste piles composed of quartz-silica-pyrite altered rocks will likely produce acidic drainage waters. The potential exists for concentrations of fluorine or rare metals in surface water and groundwater to exceed recommended limits for human consumption near both mined and unmined Climax-type deposits.

  10. In Situ Generation of Molybdenum-Based Catalyst for Alkyne Metathesis: Further Developments and Mechanistic Insights

    Directory of Open Access Journals (Sweden)

    Geng Lopez Joaquin

    2016-03-01

    Full Text Available Molybdenum-based catalysts are among the best candidates to achieve alkyne metathesis. They can be either well-defined carbynes, previously synthesized before their use, but also prepared in situ upon using stable molybdenum carbonyl complexes, or high oxidation state molybdenum salts that need a previous alkylation, both type of precursors being “activated” by hydroxyl-containing compounds such as phenols and silanols. This paper is presenting studies made on these systems, directed towards the knowledge of the reaction paths leading to the active species, and in particular to define the essential role of hydroxyl-containing co-catalyst in the formation of the active species, still ill-defined. From an analysis of the byproducts formed during the reaction, as well as of the initial products, reaction paths to access catalytic carbyne species is suggested, where the ligand environment consists of phenoxy (or siloxy groups, typically required and identified to lead to alkyne metathesis in the case of well-defined catalysts.

  11. NMR investigation on isotope effect of glycinium phosphite H sub 3 NCH sub 2 COOH centre dot H sub 2 PO sub 3

    CERN Document Server

    Ishibashi, T

    2003-01-01

    The motions of the phosphite anions and glycinium cations in H sub 3 NCH sub 2 COOH centre dot H sub 2 PO sub 3 (GPI) and its deuterated analogue (DGPI) were investigated by sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P spin-lattice relaxation times T sub 1. For both GPI and DGPI, T sub 1 's of the sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P nuclei reflect the amino rotation, methylene libration and motion of the phosphite anions, respectively. Activation energies obtained from T sub 1 's of sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P nuclei are 28.6(2), 26.0(4) and 26.2(4) kJ/mol for GPI and are 34.9(6), 27(1), 47(2) kJ/mol for DGPI, respectively. The deuterium substitution increases E sub a for the motion influenced by the hydrogen bonding. In all the observed motions, correlation times of DGPI are larger than those of GPI. (author)

  12. The role of structural effects on the reactions of alkoxyl radicals with trialkyl and triaryl phosphites. A time-resolved kinetic study.

    Science.gov (United States)

    Bietti, Massimo; Calcagni, Alessandra; Salamone, Michela

    2010-07-02

    A time-resolved kinetic study on the reactions of alkoxyl radicals with trialkyl and triaryl phosphites ((RO)(3)P: R = Me, Et, i-Pr, t-Bu; (ArO)(3)P: Ar = C(6)H(5), 2,4-(t-Bu)(2)C(6)H(3)) has been carried out. In the (RO)(3)P series, the alkoxyl radicals (cumyloxyl (CumO(*)) and benzyloxyl (BnO(*))) undergo addition to the phosphorus center with formation of intermediate tetraalkoxyphosphoranyl radicals (R'OP(*)(OR)(3): R = Me, Et, i-Pr, t-Bu; R' = Bn, Cum). The addition rate constants are influenced by steric effects, decreasing on going from R = Me to R = t-Bu and from BnO(*) to CumO(*). Rate constants for beta-scission of the phosphoranyl radicals R'OP(*)(OR)(3) have also been determined, increasing, for a given alkyl group R, in the order R' = tert-butyl < R' = benzyl < R' = cumyl and, for a given R' group, on going from R = Me to R = i-Pr. This behavior has been explained in terms of the relative stability of the radicals formed after beta-scission, suggesting moreover that steric effects play in this case a minor role. CumO(*) reacts with triaryl phosphites (ArO)(3)P to give phenoxyl radicals, with rate constants that are influenced to a limited extent by substitution of the aromatic rings. The radical scavenging ability of these substrates is briefly discussed.

  13. Método titrimétrico para determinar fosfito em amostras agroindustriais Titrimetric method for phosphite determination in agricultural chemical samples

    Directory of Open Access Journals (Sweden)

    Vanessa Pezza Franzini

    2007-04-01

    Full Text Available A new titrimetric method for the determination of phosphite in fertilizer samples, based on reaction of H3PO3 with standard iodine solution in neutral media, is proposed. Diluted samples containing ca. 0.4% m/v P2O5 are heated and titrated with 0.05 mol L-1 iodine standard until the solution becomes faint yellow. Back titration is also feasible: a slight excess of titrant is added followed by starch indicator and titration is completed taking as the end point the change in color from blue to colorless. The influence of chemical composition and pH of buffers, temperature and foreign species on waiting time and end-point detection were investigated. For the Na2HPO4/NaH2PO4 buffer (pH 6.8 at 70 °C, the titration time was 10 min, corresponding to about 127 mg iodine, 200 mg KI and 174 mg Na2HPO4 and 176 mg NaH2PO4 consumed per determination. Accuracy was checked for phosphite determination in seven fertilizer samples. Results obtained by the proposed procedure were in agreement with those obtained by spectrophotometry at 95% confidence level. The R.S.D. (n=10 for direct and back titration was 0.4% and 1.3% respectively.

  14. PURIFICATION OF URANIUM FROM URANIUM/MOLYBDENUM ALLOY

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, R; Ann Visser, A; James Laurinat, J

    2007-10-15

    The Savannah River Site will recycle a nuclear fuel comprised of 90% uranium-10% molybdenum by weight. The process flowsheet calls for dissolution of the material in nitric acid to a uranium concentration of 15-20 g/L without the formation of precipitates. The dissolution will be followed by separation of uranium from molybdenum using solvent extraction with 7.5% tributylphosphate in n-paraffin. Testing with the fuel validated dissolution and solubility data reported in the literature. Batch distribution coefficient measurements were performed for the extraction, strip and wash stages with particular focus on the distribution of molybdenum.

  15. X-ray crystal structure of arsenite-inhibited xanthine oxidase: μ-sulfido,μ-oxo double bridge between molybdenum and arsenic in the active site.

    Science.gov (United States)

    Cao, Hongnan; Hall, James; Hille, Russ

    2011-08-17

    Xanthine oxidoreductase is a molybdenum-containing enzyme that catalyzes the hydroxylation reaction of sp(2)-hybridized carbon centers of a variety of substrates, including purines, aldehydes, and other heterocyclic compounds. The complex of arsenite-inhibited xanthine oxidase has been characterized previously by UV-vis, electron paramagnetic resonance, and X-ray absorption spectroscopy (XAS), and the catalytically essential sulfido ligand of the square-pyrimidal molybdenum center has been suggested to be involved in arsenite binding through either a μ-sulfido,μ-oxo double bridge or a single μ-sulfido bridge. However, this is contrary to the crystallographically observed single μ-oxo bridge between molybdenum and arsenic in the desulfo form of aldehyde oxidoreductase from Desulfovibrio gigas (an enzyme closely related to xanthine oxidase), whose molybdenum center has an oxo ligand replacing the catalytically essential sulfur, as seen in the functional form of xanthine oxidase. Here we use X-ray crystallography to characterize the molybdenum center of arsenite-inhibited xanthine oxidase and solve the structures of the oxidized and reduced inhibition complexes at 1.82 and 2.11 Å resolution, respectively. We observe μ-sulfido,μ-oxo double bridges between molybdenum and arsenic in the active sites of both complexes. Arsenic is four-coordinate with a distorted trigonal-pyramidal geometry in the oxidized complex and three-coordinate with a distorted trigonal-planar geometry in the reduced complex. The doubly bridged binding mode is in agreement with previous XAS data indicating that the catalytically essential sulfur is also essential for the high affinity of reduced xanthine oxidoreductase for arsenite.

  16. Single-step thermal carburization synthesis of supported molybdenum carbides from molybdenum-containing methyl-silica

    Institute of Scientific and Technical Information of China (English)

    Juan Zou; Minglin Xiang; Bo Hou; Dong Wu; Yuhan Sun

    2011-01-01

    A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica (Mo-M-SiO2) in argon atmosphere at 973 K. Mo-M-SiO2 precursor was facilely obtained via a one-pot synthesis route, using (NH4)6Mo7O24·4H2O (AHM) as molybdenum sources and polymethylhydrosiloxane (PMHS) as silica sources at the initial synthetic step. The optimal C/Mo molar ratio in reaction system for complete carburization of molybdenum species was 7. The carburization process of molybdenum species followed a nontopotactic route involving a MoO2 intermediate phase, which was evidenced by XRD, N2 adsorption-desorption and in situ XPS. Formation mechanism of Mo-M-SiO2 precursor was also proposed by observation of the reaction between AHM and PMHS with TEM. Furthermore, by adding TEOS into silica sources and adjusting TEOS/PMHS mass ratio, crystal phase of molybdenum carbides transferred fromβ-Mo2C to α-MoC1-x, and SiO2 structure changed from microporous to micro/mesoporous. Catalytic performances of samples were tested using CO hydrogenation as a probe reaction. The supported molybdenum carbides exhibited high selectivity for higher alcohol synthesis compared with bulkβ-Mo2C and α-MoC1-x.

  17. Thermal ripples in model molybdenum disulfide monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Remsing, Richard C.; Klein, Michael L. [Institute for Computational Molecular Science, Center for the Computational, Design of Functional Layered Materials, and Department of Chemistry, Temple University, 1925 N. 12th St., 19122, Philadelphia, PA (United States); Waghmare, Umesh V. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, 560 064, Jakkur, Bangalore (India)

    2017-01-15

    Molybdenum disulfide (MoS{sub 2}) monolayers have the potential to revolutionize nanotechnology. To reach this potential, it will be necessary to understand the behavior of this two-dimensional (2D) material on large length scales and under thermal conditions. Herein, we use molecular dynamics (MD) simulations to investigate the nature of the rippling induced by thermal fluctuations in monolayers of the 2H and 1T phases of MoS{sub 2}. The 1T phase is found to be more rigid than the 2H phase. Both monolayer phases are predicted to follow long wavelength scaling behavior typical of systems with anharmonic coupling between vibrational modes as predicted by classic theories of membrane-like systems. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Microplastic relaxations of single and polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Pichl, W.; Weiss, B. [Wien Univ. (Austria). Inst. fuer Materialphysik; Chen, D.L.

    1998-05-01

    The microplasticity of high-purity molybdenum single crystals and of Mo polycrystals of technical purity has been investigated by relaxation step tests in uniaxial compression. A new model for the evaluation of relaxation tests in the microplastic range of b.c.c metals is presented which takes into account the decrease of the mobile dislocation density due to exhaustion of non-screw dislocations. The model allows an independent determination of the activation volume and of the microstructure parameters controlling dislocation exhaustion. The results indicate that in the high-purity single crystals the deformation rate is controlled by interactions of non-screw dislocations with the grown-in network. In the polycrystals additional interactions with impurity atoms seem to occur. In the single crystals the activity and subsequent exhaustion of two different glide systems was observed, followed by a gradual onset of screw dislocation motion. (orig.) 26 refs.

  19. Radio Frequencv Induction Plasma Spraying of Molybdenum

    Institute of Scientific and Technical Information of China (English)

    Jiang Xianliang(蒋显亮); Maher Boulos

    2003-01-01

    Radio frequency (RF) induction plasma was used to make free-standing depositionof molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were inves-tigated. The effect of process parameters such as plasma power, chamber pressure, and spraydistance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM)was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Exper-imental results show that less Mo particles are spheroidized when compared to the number ofspheroidized tungsten (W) particles at the same powder feed rate under the same plasma spraycondition. Molten Mo particles can be sufficiently flattened on substrate. The influence of theprocess parameters on the flattening behavior is not significant. Mo deposit is not as dense as Wdeposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powderwith a large particle size is not evident under the low pressure plasma spray.

  20. Innovative Molybdenum Alloy for Extreme Operating Conditions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Molybdenum has been identified as a promising material for many high temperature NASA applications due to its high melting temperature, resistance to liquid metals,...

  1. Electroanalytical determination of tungsten and molybdenum in proteins.

    Science.gov (United States)

    Hagedoorn, P L; van't Slot, P; van Leeuwen, H P; Hagen, W R

    2001-10-01

    Recent crystal structure determinations accelerated the progress in the biochemistry of tungsten-containing enzymes. In order to characterize these enzymes, a sensitive determination of this metal in protein-containing samples is necessary. An electroanalytical tungsten determination has successfully been adapted to determine the tungsten and molybdenum content in enzymes. The tungsten and molybdenum content can be measured simultaneously from 1 to 10 microg of purified protein with little or no sample handling. More crude protein samples require precipitation of interfering surface active material with 10% perchloric acid. This method affords the isolation of novel molybdenum- and tungsten-containing proteins via molybdenum and tungsten monitoring of column fractions, without using radioactive isotopes. A screening of soluble proteins from Pyrococcus furiosus for tungsten, using anion-exchange column chromatography to separate the proteins, has been performed. The three known tungsten-containing enzymes from P. furiosus were recovered with this screening.

  2. Isotopically Modified Molybdenum: Production for Application in Nuclear Energy

    Science.gov (United States)

    Smirnov, A. Yu.; Bonarev, A. K.; Sulaberidze, G. A.; Borisevich, V. D.; Kulikov, G. G.; Shmelev, A. N.

    The possibility to use the isotopically modified molybdenum as a constructive material for the fuel rods of light water and fast reactors is discussed. The calculations demonstrate that the isotopically modified molybdenum with an average neutron absorption cross-section comparable to that of zirconium can be obtained with the reasonable for practice cost by a cascade of gas centrifuges, specially designed for separation of non-uranium isotopes.

  3. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  4. Speciation of aluminium, arsenic and molybdenum in excessively limed lakes.

    Science.gov (United States)

    Sjöstedt, Carin; Wällstedt, Teresia; Gustafsson, Jon Petter; Borg, Hans

    2009-09-01

    The possible existence of the potentially toxic oxyanions of Al (Al(OH)(4)(-)), As (HAsO(4)(2-)), and Mo (MoO(4)(2-)) was examined in excessively limed lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively limed lakes (pH 7.1-7.7) and one acidic lake (pH approximately 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively limed lakes were to a large extent present in the dialysable fraction (>79% and >92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH)(4)(-) ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.

  5. Speciation of aluminium, arsenic and molybdenum in excessively limed lakes

    Energy Technology Data Exchange (ETDEWEB)

    Sjoestedt, Carin, E-mail: carinsj@kth.se [Department of Land and Water Resources Engineering, KTH (Royal Institute of Technology), Teknikringen 76, SE-100 44 Stockholm (Sweden); Waellstedt, Teresia [Department of Aquatic Sciences and Assessment, SLU (Swedish University of Agricultural Sciences), P.O. Box 7050, SE-750 07 Uppsala (Sweden); Gustafsson, Jon Petter [Department of Land and Water Resources Engineering, KTH (Royal Institute of Technology), Teknikringen 76, SE-100 44 Stockholm (Sweden); Borg, Hans [Department of Applied Environmental Science, SU (Stockholm University), SE-106 91 Stockholm (Sweden)

    2009-09-01

    The possible existence of the potentially toxic oxyanions of Al (Al(OH){sub 4}{sup -}), As (HAsO{sub 4}{sup 2-}), and Mo (MoO{sub 4}{sup 2-}) was examined in excessively limed lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively limed lakes (pH 7.1-7.7) and one acidic lake (pH {approx} 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively limed lakes were to a large extent present in the dialysable fraction (> 79% and > 92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH){sub 4}{sup -} ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.

  6. Risk of overestimation of urinary cadmium concentrations: interference from molybdenum

    Directory of Open Access Journals (Sweden)

    Cañas A.I.

    2013-04-01

    Full Text Available We show here that the selection of analytical method is critical when measuring low levels of cadmium in human urine. Cadmium is today usually analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS, which has a higher sensitivity than Atomic Absorption Spectroscopy (AAS. ICP-MS cadmium measurements show interference from tin (114Sn and molybdenum oxides, which can result in an overestimation of cadmium levels. The 114Sn interference is stable and can be mathematically corrected. Molybdenum concentrations in urine are variable and different from individual to individual. We have estimated the degree of error which molybdenum interference introduces in the measurement of cadmium in urine by conventional ICP-MS. 268 urine samples from mothers and their children were measured. Removal of the molybdenum oxide interference (DRC-ICP-MS method reduced urinary cadmium concentrations significantly (47.8%. The urinary molybdenum concentration in children was higher than in their mothers, resulting in greater overestimation. Our results clearly show that the DRC method is essential for reliable measurements of urinary cadmium concentrations, particularly in children. Furthermore, care should be taken when comparing Human Biomonitoring data for cadmium in urine and attention should be paid to which analytical method has been used (e.g. AAS and ICP-Ms, and especially if the measurements have been corrected for molybdenum interference.

  7. Solvent extraction, ion chromatography, and mass spectrometry of molybdenum isotopes.

    Science.gov (United States)

    Dauphas, N; Reisberg, L; Marty, B

    2001-06-01

    A procedure was developed that allows precise determination of molybdenum isotope abundances in natural samples. Purification of molybdenum was first achieved by solvent extraction using di(2-ethylhexyl) phosphate. Further separation of molybdenum from isobar nuclides was obtained by ion chromatography using AG1-X8 strongly basic anion exchanger. Finally, molybdenum isotopic composition was measured using a multiple collector inductively coupled plasma hexapole mass spectrometer. The abundances of molybdenum isotopes 92, 94, 95, 96, 97, 98, and 100 are 14.8428(510), 9.2498(157), 15.9303(133), 16.6787(37), 9.5534(83), 24.1346(394), and 9.6104(312) respectively, resulting in an atomic mass of 95.9304(45). After internal normalization for mass fractionation, no variation of the molybdenum isotopic composition is observed among terrestrial samples within a relative precision on the order of 0.00001-0.0001. This demonstrates the reliability of the method, which can be applied to searching for possible isotopic anomalies and mass fractionation.

  8. Extraction and Spectrophotometric Determination of Molybdenum with o-Hydroxythiophenols and Aromatic Amines

    OpenAIRE

    A. Z. Zalov; N. A. Verdizade; A. B. Hadjieva

    2015-01-01

    The interaction of molybdenum (VI) with o-hydroxythiophenol derivatives (HTPDs) and aromatic amines (AAs) was studied. The following three HTPDs, which contain different halogen atoms at position 5, were used: 2-hydroxy-5-chlorothiophenol(HCTP), 2-hydroxy-5-bromothiophenol (HBTP), 2-hydroxy-5-iodothiophenol (HITP)]. The examined AAs were aniline (An), N-methylaniline (mAn) and N,N-dimethylaniline (dAn). The obtained ternary complexes have a composition of 1:2:2 {Mo(V):HBTP:AA}.Optimal conditi...

  9. Fosfitos para o controle de podridões pós-colheita em maçãs ‘Fuji’ durante o armazenamento refrigerado Use of phosphites for rot control during cold storage of ‘Fuji’ apples

    Directory of Open Access Journals (Sweden)

    Auri Brackmann

    2004-08-01

    Full Text Available Foi conduzido um experimento com o objetivo de avaliar o efeito da aplicação de adubos foliares contendo fosfitos de potássio e fosfitos de cálcio mais boro sobre o controle de podridões em maçãs ‘Fuji’ durante a frigoconservação. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições de 25 frutos. Foram realizadas quatro lesões distribuídas de forma eqüidistante na região equatorial dos frutos, com 3mm de diâmetro e 5mm de profundidade. Os frutos foram submersos em uma solução com suspensão de esporos, onde permaneceram por 20 segundos. Após, foram aplicados os tratamentos: 1 - Testemunha (água; 2 - Iprodione (75g 100L-1; 3 - cloreto de cálcio( CaCl2 a 2%; 4 - fosfito de potássio (250mL 100L-1 + CaCl2 (2%; 5 - fosfito de potássio (250mL 100L-1; 6 - fosfito de cálcio mais boro (300mL 100L-1; e 7 - fosfito de potássio (250mL 100L-1 na suspensão de esporos por uma hora. Os frutos foram armazenados em ambiente refrigerado à temperatura de 0°C durante 14 dias. As avaliações foram realizadas na saída da câmara e aos 2, 4, 6 e 8 dias a 20°C. Verificou-se que os frutos tratados com fosfito de potássio (250mL 100L-1 + CaCl2 (2% apresentaram a menor incidência de podridões e o menor diâmetro de lesão. Esses resultados foram semelhantes aos obtidos com a aplicação do fungicida padrão Iprodione e superiores à aplicação de fosfito de potássio isoladamente. O uso de fosfito de cálcio mais boro não foi eficiente.This experiment aimed to evaluate the effectiveness of potassium (K phosphite and calcium (Ca + borum (B phosphite to control rot during cold storage of ‘Fuji’ apples. Four equidistant lesions were made in the central region of the fruits, measuring 5mm wide and 3mm deep. After the treatments, fruits were submerged for 20 seconds in a spore suspension, except for the last treatment, in wich the immersion lasted one hour. The treatments were as follow: 1

  10. Chemiluminescence Determination of Molybdenum by on-Line Reduction with a Flow Injection System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (Ⅲ) produced by a Jones reductor was investigated using a flow injection system. On the basis of this, a novel method for the determination of trace amount of molybdenum has been established. The emission intensity was linear with molybdenum concentration in the range of 0.1-1000 ng/mL; the detection limit was 0.02 ng/mL molybdenum; the relative standard deviation was less than 2% for the determination of 0.1 ng/mL molybdenum (n=11). The method has been applied successfully to the analysis of trace molybdenum in water and steel samples.

  11. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    Science.gov (United States)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  12. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Tsechanski, A. [Ben-Gurion University of the Negev, Department of Nuclear Engineering, P.O. Box 653, Beer-Sheva 84105 (Israel); Bielajew, A.F. [Department of Nuclear Engineering and Radiological Sciences, The University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Archambault, J.P.; Mainegra-Hing, E. [National Research Council of Canada, Ionizing Radiation Standards Laboratory, Ottawa, ON K1A 0R6 (Canada)

    2016-01-01

    A new “one-stage” approach for production of {sup 99}Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of {sup 99}Mo via the photoneutron reaction {sup 100}Mo(γ,n){sup 99}Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r{sub 0}) W target, for target thickness z > 1.84r{sub 0}, where r{sub 0} is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r{sub 0}) for target thickness case: z ⩾ 2.0r{sub 0}. It is shown for the one-stage approach with thicknesses of (1.84–2.0)r{sub 0}, that the {sup 99}Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r{sub 0}) in the traditional two-stage approach (W converter and separate {sup 99}Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the {sup 99}Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity

  13. Effect of molybdenum addition on the mechanical properties of sinter-forged Fe–Cu–C alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rathore, Sanjay S., E-mail: rathore.sanjaysingh@gmail.com; Salve, Milind M., E-mail: milindrowling@gmail.com; Dabhade, Vikram V., E-mail: vvdabfmt@iitr.ac.in

    2015-11-15

    Molybdenum provides solid solution strengthening, enhances hardenability and has thus been used to improve mechanical properties of ferrous alloys significantly. The present study reports the effect of molybdenum addition on the properties of sinter-forged Fe–Cu–C alloys prepared using elemental powders under various heat treatment conditions. The elemental powder mixtures were compacted at a pressure of 500 MPa followed by sintering at 1120 °C in N{sub 2}–20%H{sub 2} atmosphere. Further, the sintered compacts were immediately forged at the sintering temperature in a closed die. The sinter-forged compacts were further homogenized and then heat treated under different cooling rates. Enhancement of the mechanical properties (hardness and tensile strength) were observed with Mo addition and increase in severity of quench. Hardness of air cooled samples was slightly lower than that of the water quenched samples but comparable with oil quenched samples. However, no significant increase in hardness was observed beyond 1.5 wt% Mo addition for all cooling conditions. At higher molybdenum content ductility was retained due to stabilization of ferrite phase by molybdenum. The microstructural study showed mostly ferrite–pearlite structure in furnace cooled condition whereas a complex microstructure was observed in the faster cooling conditions. Grain refinement was also observed with molybdenum addition. - Highlights: • Mo (0.25–4.0 wt%) addition in sinter-forged Fe–2Cu–0.65C alloys was investigated. • Effect of heat treatment on mechanical properties and microstructure was discussed. • Hardness and strength increased with Mo addition at the expense of ductility. • Hardness in air cooled condition was comparable with oil/water cooled conditions.

  14. Molybdenum oxide and molybdenum oxide-nitride back contacts for CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Drayton, Jennifer A., E-mail: drjadrayton@yahoo.com; Geisthardt, Russell M., E-mail: Russell.Geisthardt@gmail.com; Sites, James R., E-mail: james.sites@colostate.edu [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); Williams, Desiree D., E-mail: daisyw@rams.colostate.edu; Cramer, Corson L., E-mail: clcramer@rams.colostate.edu; Williams, John D., E-mail: john.d.williams@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

    2015-07-15

    Molybdenum oxide (MoO{sub x}) and molybdenum oxynitride (MoON) thin film back contacts were formed by a unique ion-beam sputtering and ion-beam-assisted deposition process onto CdTe solar cells and compared to back contacts made using carbon–nickel (C/Ni) paint. Glancing-incidence x-ray diffraction and x-ray photoelectron spectroscopy measurements show that partially crystalline MoO{sub x} films are created with a mixture of Mo, MoO{sub 2}, and MoO{sub 3} components. Lower crystallinity content is observed in the MoON films, with an additional component of molybdenum nitride present. Three different film thicknesses of MoO{sub x} and MoON were investigated that were capped in situ in Ni. Small area devices were delineated and characterized using current–voltage (J-V), capacitance–frequency, capacitance–voltage, electroluminescence, and light beam-induced current techniques. In addition, J-V data measured as a function of temperature (JVT) were used to estimate back barrier heights for each thickness of MoO{sub x} and MoON and for the C/Ni paint. Characterization prior to stressing indicated the devices were similar in performance. Characterization after stress testing indicated little change to cells with 120 and 180-nm thick MoO{sub x} and MoON films. However, moderate-to-large cell degradation was observed for 60-nm thick MoO{sub x} and MoON films and for C/Ni painted back contacts.

  15. Complex

    African Journals Online (AJOL)

    CLEMENT O BEWAJI

    Schiff bases and their complex compounds have been studied for their .... establishing coordination of the N–(2 – hydroxybenzyl) - L - α - valine Schiff base ..... (1967); “Spectrophotometric Identification of Organic Compounds”, Willey, New.

  16. Tris(2,2,2-trifluoroethyl) phosphite as an electrolyte additive for high-voltage lithium-ion batteries using lithium-rich layered oxide cathode

    Science.gov (United States)

    Pires, Julie; Castets, Aurore; Timperman, Laure; Santos-Peña, Jesùs; Dumont, Erwan; Levasseur, Stéphane; Tessier, Cécile; Dedryvère, Rémi; Anouti, Mérièm

    2015-11-01

    In this paper, we report positive effect of Tris(2,2,2-trifluoroethyl) phosphite (TTFP) as additive during initial activation and cycling of Li-rich-NMC xLi2MnO3-(1 - x)LiMO2 (x >> 1; M = Ni, Co, Mn) cathode in EC/DMC + 1 M LiPF6 electrolyte. Firstly conductivity and viscosity of electrolyte with x wt.% TTFP; 0 wt.% NMC full cell is maintained after 50 cycles at C rate. Finally, XPS analysis of Li-rich -NMC electrodes show presence of TTFP on the surface during cycling and confirm the presence of Mn3+ at the end of discharge. The convergence of all characterizations indicates that TTFP should act as a catalyst to several surface reactions which are beneficial to long cycling cell performances.

  17. Reaction of 3-Amino-1,2,4-Triazole with Diethyl Phosphite and Triethyl Orthoformate: Acid-Base Properties and Antiosteoporotic Activities of the Products

    Directory of Open Access Journals (Sweden)

    Patrycja Miszczyk

    2017-02-01

    Full Text Available The reaction of diethyl phosphite with triethyl orthoformate and a primary amine followed by hydrolysis is presented, and the reaction was suitable for the preparation of (aminomethylenebisphosphonates. 3-Amino-1,2,4-triazole was chosen as an interesting substrate for this reaction because it possesses multiple groups that can serve as the amino component in the reaction—namely, the side-chain and triazole amines. This substrate readily forms 1,2,4-triazolyl-3-yl-aminomethylenebisphosphonic acid (compound 1 as a major product, along with N-ethylated bisphosphonates as side products. The in vitro antiproliferative effects of the synthesized aminomethylenebisphosphonic acids against J774E macrophages were determined. These compounds exhibit similar activity to zoledronic acid and higher activity than incadronic acid.

  18. Prototropic migrations in the phosphorylation of imidoyl chlorides containing hydrogen on the N-. cap alpha. -carbon atom. III. Phosphorylation of substituted N-benzylbenzimidoyl chlorides with triethyl phosphite

    Energy Technology Data Exchange (ETDEWEB)

    Onys' ko, P.P.; Kim, T.V.; Kiseleva, E.I.; Sinitsa, A.D.

    1987-11-20

    The reactions of substituted N-benzylbenzimidoyl chlorides with triethyl phosphite lead to imidoylphosphonates, which suffer a 1,3-H shift with the formation of ..cap alpha..-phosphorylated azomethines. In phosphorylated 1,3-diaryl-substituted azaallyl systems the most stable isomer is that in which the phosphoryl group is linked to the sp/sup 3/-carbon atom of the C=N-CH triad. Substituents in the benzene nucleus do not influence the position of the prototropic equilibrium. The spectra were recorded with the external standards HMDS and 85% H/sub 3/PO/sub 4/ and the internal standard CCl/sub 3/F for /sup 1/H, /sup 31/P, and /sup 19/P nuclei, respectively.

  19. Structure, activity and kinetics of supported molybdenum oxide and mixed molybdenum-vanadium oxide catalysts prepared by flame spray pyrolysis for propane OHD

    DEFF Research Database (Denmark)

    Høj, Martin; Kessler, Thomas; Beato, Pablo

    2013-01-01

    reflectance UV-vis spectroscopy and evaluated as catalysts for the oxidative dehydrogenation (ODH) of propane. The results show that samples with high specific surface areas between 122 and 182 m2/g were obtained, resulting in apparent MoOx and VOx surface densities from 0.7 to 7.7 nm -2 and 1.5 to 1.9 nm-2......, respectively. Raman spectroscopy, UV-vis spectroscopy and XRD confirmed the high dispersion of molybdenum and vanadia species on γ-Al2O3 as the main crystalline phase. Only at the highest loading of 15 wt% Mo, with theoretically more than monolayer coverage, some crystalline molybdenum oxide was observed....... For the mixed molybdenum-vanadium oxide catalysts the surface species were separate molybdenum oxide and vanadium oxide monomers at low loadings of molybdenum, but with increasing molybdenum loading interactions between surface molybdenum and vanadium oxide species were observed with Raman spectroscopy...

  20. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Science.gov (United States)

    Baltrusaitis, Jonas; Mendoza-Sanchez, Beatriz; Fernandez, Vincent; Veenstra, Rick; Dukstiene, Nijole; Roberts, Adam; Fairley, Neal

    2015-01-01

    Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  1. Ionic liquid-based dispersive liquid-liquid microextraction and enhanced spectrophotometric determination of molybdenum (VI) in water and plant leaves samples by FO-LADS.

    Science.gov (United States)

    Gharehbaghi, Maysam; Shemirani, Farzaneh

    2011-02-01

    A new simple and rapid ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) has been applied to preconcentrate trace levels of molybdenum (VI) as a prior step to its enhanced determination by fiber optic-linear array detection spectrophotometry (FO-LADS). In this method, a small amount of [Hmim][Tf(2)N] (1-hexyl-3-methylimmidazolium bis (trifluormethylsulfonyl) imid) as an extraction solvent was applied to extract molybdenum - pyrogallol red complex, which was formed in an aqueous solution in the presence of N-cetyl-N-N-N-trimethyl ammonium chloride as a sensitizing agent. Under optimum conditions, enhancement factor, detection limit and relative standard deviation (n=5, for 30 μg L(-1) of molybdenum (VI)) in 10 mL water sample were 72.6, 1.43 μg L(-1) and 2.8%, respectively.

  2. Molybdenum oxides versus molybdenum sulfides: geometric and electronic structures of Mo₃X(y)⁻ (X = O, S and y = 6, 9) clusters.

    Science.gov (United States)

    Mayhall, Nicholas J; Becher, Edwin L; Chowdhury, Arefin; Raghavachari, Krishnan

    2011-03-24

    We have conducted a comparative computational investigation of the molecular structure and water adsorption properties of molybdenum oxide and sulfide clusters using density functional theory methods. We have found that while Mo₃O₆⁻ and Mo₃S₆⁻ assume very similar ring-type isomers, Mo₃O₉⁻ and Mo₃S₉⁻ clusters are very different with Mo₃O₉⁻ having a ring-type structure and Mo₃S₉⁻ having a more open, linear-type geometry. The more rigid ∠(Mo-S-Mo) bond angle is the primary geometric property responsible for producing such different lowest energy isomers. By computing molecular complexation energies, it is observed that water is found to adsorb more strongly to Mo₃O₆⁻ than to Mo₃S₆⁻, due to a stronger oxide-water hydrogen bond, although dispersion effects reduce this difference when molybdenum centers contribute to the binding. Investigating the energetics of dissociative water addition to Mo₃X₆⁻ clusters, we find that, while the oxide cluster shows kinetic site-selectivity (bridging position vs terminal position), the sulfide cluster exhibits thermodynamic site-selectivity.

  3. Extraction and Spectrophotometric Determination of Molybdenum with o-Hydroxythiophenols and Aromatic Amines

    Directory of Open Access Journals (Sweden)

    A. Z. Zalov

    2015-06-01

    Full Text Available The interaction of molybdenum (VI with o-hydroxythiophenol derivatives (HTPDs and aromatic amines (AAs was studied. The following three HTPDs, which contain different halogen atoms at position 5, were used: 2-hydroxy-5-chlorothiophenol(HCTP, 2-hydroxy-5-bromothiophenol (HBTP, 2-hydroxy-5-iodothiophenol (HITP]. The examined AAs were aniline (An, N-methylaniline (mAn and N,N-dimethylaniline (dAn. The obtained ternary complexes have a composition of 1:2:2 {Mo(V:HBTP:AA}.Optimal conditions for their liquid-liquid extraction (LLE were found: organic solvent (chloroform, pH (4-6, concentration of the reagents ((1.3-1.510–3moldm–3 (HTPD and (1.2-1.510–3moldm–3 (AA and extraction time(colour develops almost immediately after the reagents addition. The absorbance of the extracts is stable for at least 48 hours. The optimum shaking time is 10 min.. Under the optimal conditions, the complexes have absorption maxima (max at 515-538 nm and molar absorptivities (max between 3.1104dm3mol–1 cm–1. The degrees of extraction were 98.4%. The results suggested that linear relationships exist between the spectral characteristics (max or max and some fundamental properties of the halogen substituent in the HTPD (atomic mass and electronegativity. The effect of foreign ions on the LLE-spectrophotometric determination of molybdenum was examined and two sensitive, selective and precise procedures for molybdenum determination were proposed. The relative standard deviations for Mo content of (3-510–4 % were 4% (HCTP-An procedure and 3% (HBTP-An procedure.

  4. Amorphous molybdenum silicon superconducting thin films

    Directory of Open Access Journals (Sweden)

    D. Bosworth

    2015-08-01

    Full Text Available Amorphous superconductors have become attractive candidate materials for superconducting nanowire single-photon detectors due to their ease of growth, homogeneity and competitive superconducting properties. To date the majority of devices have been fabricated using WxSi1−x, though other amorphous superconductors such as molybdenum silicide (MoxSi1−x offer increased transition temperature. This study focuses on the properties of MoSi thin films grown by magnetron sputtering. We examine how the composition and growth conditions affect film properties. For 100 nm film thickness, we report that the superconducting transition temperature (Tc reaches a maximum of 7.6 K at a composition of Mo83Si17. The transition temperature and amorphous character can be improved by cooling of the substrate during growth which inhibits formation of a crystalline phase. X-ray diffraction and transmission electron microscopy studies confirm the absence of long range order. We observe that for a range of 6 common substrates (silicon, thermally oxidized silicon, R- and C-plane sapphire, x-plane lithium niobate and quartz, there is no variation in superconducting transition temperature, making MoSi an excellent candidate material for SNSPDs.

  5. Vertically aligned biaxially textured molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Rahul [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Riley, Michael [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lee, Sabrina [US Army Armament Research, Development and Engineering Center, Benet Labs, Watervliet, New York 12189 (United States); Lu, Toh-Ming [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2011-09-15

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

  6. Groundwater Molybdenum from Emerging Industries in Taiwan.

    Science.gov (United States)

    Tsai, Kuo-Sheng; Chang, Yu-Min; Kao, Jimmy C M; Lin, Kae-Long

    2016-01-01

    This study determined the influence of emerging industries development on molybdenum (Mo) groundwater contamination. A total of 537 groundwater samples were collected for Mo determination, including 295 samples from potentially contaminated areas of 3 industrial parks in Taiwan and 242 samples from non-potentially contaminated areas during 2008-2014. Most of the high Mo samples are located downstream from a thin film transistor-liquid crystal display (TFT-LCD) panel factory. Mean groundwater Mo concentrations from potentially contaminated areas (0.0058 mg/L) were significantly higher (p groundwater and surface water contamination. Nine samples of groundwater exceed the World Health Organization's suggested drinking water guideline of 0.07 mg/L. A non-carcinogenic risk assessment for Mo in adults and children using the Mo concentration of 0.07 mg/L yielded risks of 0.546 and 0.215, respectively. These results indicate the importance of the development of a national drinking water quality standard for Mo in Taiwan to ensure safe groundwater for use. According to the human health risk calculation, the groundwater Mo standard is suggested as 0.07 mg/L. Reduction the discharge of Mo-contaminated wastewater from factories in the industrial parks is also the important task in the future.

  7. Electro-oxidation process for molybdenum concentrates

    Institute of Scientific and Technical Information of China (English)

    FU Jian-gang; ZHONG Hong; BU Xiang-ming; WANG Fu-li

    2005-01-01

    Sodium hypochlorite was used to treat the standard molybdenum concentrates; the oxidization conditions for sodium hypochlorite were investigated, and the electro-oxidation process was performed. The results indicate that in the suitable conditions, such as temperature around 25 ℃, NaCl concentration 4.0 mol/L, mass ratio of ore slurry liquid to solid (mL/mS) 20, electric charge per gram Mo 0.522 C, pH value of original slurry 8, anodic current density 700 A·m-2 (cell potential 2.7-2.9 V), the Mo leaching rate and the current efficiency reach 98% and 36%, respectively. In order to overcome some shortages of the electro-oxidation process, such as low current efficiency, low Mo concentration in the leaching solution, ultrasonic was adopted to intensify the leaching process. The results show that the Mo leaching rate exceeds 98%, current efficiency increases from 36% to 50% and the Mo concentration in the leaching solution reaches about 60 g/L at low mL/mS of 8 and low electric charge of 0.373 C.

  8. Structural phase transitions in monolayer molybdenum dichalcogenides

    Science.gov (United States)

    Choe, Duk-Hyun; Sung, Ha June; Chang, Kee Joo

    2015-03-01

    The recent discovery of two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) has provided opportunities to develop ultimate thin channel devices. In contrast to graphene, the existence of moderate band gap and strong spin-orbit coupling gives rise to exotic electronic properties which vary with layer thickness, lattice structure, and symmetry. TMDs commonly appear in two structures with distinct symmetries, trigonal prismatic 2H and octahedral 1T phases which are semiconducting and metallic, respectively. In this work, we investigate the structural and electronic properties of monolayer molybdenum dichalcogenides (MoX2, where X = S, Se, Te) through first-principles density functional calculations. We find a tendency that the semiconducting 2H phase is more stable than the metallic 1T phase. We show that a spontaneous symmetry breaking of 1T phase leads to various distorted octahedral (1T') phases, thus inducing a metal-to-semiconductor transition. We discuss the effects of carrier doping on the structural stability and the modification of the electronic structure. This work was supported by the National Research Foundation of Korea (NRF) under Grant No. NRF-2005-0093845 and Samsung Science and Technology Foundation under Grant No. SSTFBA1401-08.

  9. The potential roles of lime and molybdenum on the growth, nitrogen ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-04-26

    Apr 26, 2010 ... Experiments with soybean have shown that molybdenum fertilization in .... Evidence in the literature shows that lime, organic and different ...... Foliar application of molybdenum in common beans. I. Nitrogenase and reductase ...

  10. Ultra-rapid processing of refractory carbides; 20 s synthesis of molybdenum carbide, Mo2C.

    Science.gov (United States)

    Vallance, Simon R; Kingman, Sam; Gregory, Duncan H

    2007-02-21

    The microwave synthesis of molybdenum carbide, Mo(2)C, from carbon and either molybdenum metal or the trioxide has been achieved on unprecedented timescales; Ex- and in-situ characterisation reveals key information as to how the reaction proceeds.

  11. Largest domestic tungsten and molybdenum deep processing project finding its home in Luan-chuan

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>Recently, a tungsten and molybdenum deep processing project was formally executed with a joint investment of 300 million yuan from Luanchuan Molybdenum Mining & Smelting Co., Ltd, Beijing Tian-Long Tungsten & Mo-

  12. Flotation technology of refractory low-grade molybdenum ore

    Institute of Scientific and Technical Information of China (English)

    Du Shuhua; Luo Zhenfu

    2013-01-01

    Because of the low grade,high oxidation rate and the accumulation of little associated metal sulfide ore in the molybdenum concentrate during flotation,the Qingyang molybdenum ore is difficult to beneflciate.The experimental studies of grinding fineness,the amount of roughing modifier,depressant and collector were completed.In the cleaning process,the contrast experiments of one regrinding.the regrinding and scrubbing,two-stage regrinding was carried.The result shows that the grade of molybdenum ore concentrate is 45.31%,the recovery is 65.98% and the rich ore ratio reaches 20.59% by the regrinding and scrubbing seven cleaning,the regrinding of concentrations from middling of molybdenum-sulfur separation.The regularly-concentrated material from the apparatus was as the middling products.Hence,ideal beneficiation index can be obtained with a rational mineral processing,which offers new beneficiating technology for the refractory low-grade molybdenum ore in China.

  13. Molybdenum (VI) binded to humic and nitrohumic acid models in aqueous solutions salicylic, 3-nitrosalicylic, 5-nitrosalicylic and 3,5 dinitrosalicylic acids, Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Merce, Ana Lucia R.; Lopes, Priscilla P.; Mangricha, Antonio S. [Parana Univ., Curitiba, PR (Brazil). Dept. de Quimica]. E-mail: anamerce@ufpr.br; Levy, Noel M. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil)

    2006-05-15

    In this work electrochemical and Ultraviolet-Visible studies were performed in solutions of salicylic acid models of humic and nitrohumic acids, a laboratory artifact, and molybdenum in order to determine the affinity of these models towards the metal ion. Molybdenum, which plays a very important role in the soil chemistry, and together with humic substances, impart fertility to soil and water and is a key element in the activity of nitrogenase. The obtained results showed that at least one complexed species is present at the pH range of 6.3 to 8.0, even for the less basic chosen models, the nitrosalicylic acids. Previous study showed that phthalic and nitrophthalic, also humic and nitrohumic acids model compounds, presented complexed species with molybdenum only till pH 6.5. The calculated formation constants showed that the substitution of the nitro group in the orto position was less favoured than in the para substitution, probably due to a steric hindrance in the former, which was clearly seen in the double substituted salicylic nitro derivative. The cyclic voltammetry as well as the Ultraviolet-Visible obtained spectra were able to show that the chemistry of molybdenum in aqueous solutions as the pH is increased is very complex, and the molybdate stops acting as an anion only after pH around 4, when it finally becomes a cation MoO{sub 2}{sup 2+} (M). (author)

  14. Molybdenum (VI binded to humic and nitrohumic acid models in aqueous solutions. Salicylic, 3-nitrosalicylic, 5-nitrosalicylic and 3,5 dinitrosalicylic acids: part 2

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia R.

    2006-01-01

    Full Text Available In this work electrochemical and Ultraviolet-Visible studies were performed in solutions of salicylic acid models of humic and nitrohumic acids, a laboratory artifact, and molybdenum in order to determine the affinity of these models towards the metal ion. Molybdenum, which plays a very important role in the soil chemistry, and together with humic substances, impart fertility to soil and water and is a key element in the activity of nitrogenase. The obtained results showed that at least one complexed species is present at the pH range of 6.3 to 8.0, even for the less basic chosen models, the nitrosalicylic acids. Previous study showed that phthalic and nitrophthalic, also humic and nitrohumic acids model compounds, presented complexed species with molybdenum only till pH 6.5. The calculated formation constants showed that the substitution of the nitro group in the orto position was less favoured than in the para substitution, probably due to a steric hindrance in the former, which was clearly seen in the double substituted salicylic nitro derivative. The cyclic voltammetry as well as the Ultraviolet-Visible obtained spectra were able to show that the chemistry of molybdenum in aqueous solutions as the pH is increased is very complex, and the molybdate stops acting as an anion only after pH around 4, when it finally becomes a cation MoO2(2+ (M.

  15. Fosfitos aplicados em pós-colheita reduzem o mofo-azul em maçãs 'Fuji' e 'Gala' Postharvest application of phosphites reduces blue mold on 'Fuji' and 'Gala' apples

    Directory of Open Access Journals (Sweden)

    Luiz Eduardo Bassay Blum

    2007-08-01

    Full Text Available O mofo-azul (Penicillium expansum é uma podridão pós-colheita comum em maçãs (Malus domestica. O uso de substâncias menos ofensivas ao ambiente, como o fosfito (ácido fosforoso, é uma das alternativas de controle dessa doença. Visou-se, então, a avaliar neste estudo a eficiência de fosfito-K (40% de P2O5 e 30% de K2O e fosfito-CaB (10,7% de P2O5, 3,89% de Ca e 0,5% de B no controle do mofo-azul em maçãs 'Fuji' e 'Gala'. Os testes foram delineados em blocos ao acaso com seis repetições de 20 frutos cada. Os frutos foram desinfestados em hipoclorito de Na (1% por três minutos, lavados em água esterilizada, feridos (1mm de diâmetro e de profundidade com agulha em quatro pontos eqüidistantes, imersos nos tratamentos por 15 minutos e armazenados a 15-20ºC. Nas suspensões contaminadas com Penicillium expansum (10² conídios.mL-1, foram adicionadas as seguintes substâncias: benomil (150 mg.L-1, fosfito-K (0,5 a 1,5 mL.L-1 e fosfito-CaB (1,5 a 3,0 mL.L-1. As maçãs 'Fuji' e 'Gala' imersas em água com fosfito-CaB (1,5 mL.L-1, fosfito-K (0,5-1,5 mL.L-1 ou benomil (150 mg.L-1 foram menos afetadas pelo mofo-azul. A aplicação de fosfito-K (1,5 mL.L-1 ou benomil (150 mg.L-1 nos frutos foi mais eficiente do que os demais tratamentos no controle do mofo-azul.Blue mold (Penicillium expansum is a common postharvest disease of apples (Malus domestica. Applications of less hazardous substances to the environment, such as phosphite (phosphonic acid, is an alternative to the control of blue mold. The main goal of this study was to evaluate the efficiency of phosphite-K (40% P2O5 and 30% K2O and phosphite-CaB (10.7% P2O5, 3.89% Ca, and 0.5% B for the control of blue mold on 'Fuji' and 'Gala' apples. Tests were designed in randomized blocks with six replications of 20 fruits. Fruits were decontaminated with Na hypochlorite (1% for three minutes, washed with sterilized water, needle wounded (with a diameter and deepness of 1mm in four

  16. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory.

    Science.gov (United States)

    Lima, Frederico A; Bjornsson, Ragnar; Weyhermüller, Thomas; Chandrasekaran, Perumalreddy; Glatzel, Pieter; Neese, Frank; DeBeer, Serena

    2013-12-28

    X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.

  17. Purification of molybdenum oxide, growth and characterization of medium size zinc molybdate crystals for the LUMINEU program

    Directory of Open Access Journals (Sweden)

    Shlegel V.N.

    2014-01-01

    Full Text Available The LUMINEU program aims at performing a pilot experiment on neutrinoless double beta decay of 100Mo using radiopure ZnMoO4 crystals operated as scintillating bolometers. Growth of high quality radiopure crystals is a complex task, since there are no commercially available molybdenum compounds with the required levels of purity and radioactive contamination. This paper discusses approaches to purify molybdenum and synthesize compound for high quality radiopure ZnMoO4 crystal growth. A combination of a double sublimation (with addition of zinc molybdate with subsequent recrystallization in aqueous solutions (using zinc molybdate as a collector was used. Zinc molybdate crystals up to 1.5 kg were grown by the low-thermal-gradient Czochralski technique, their optical, luminescent, diamagnetic, thermal and bolometric properties were tested.

  18. Purification of molybdenum oxide, growth and characterization of medium size zinc molybdate crystals for the LUMINEU program

    CERN Document Server

    Shlegel, V N; Boiko, R S; Chapellier, M; Chernyak, D M; Coron, N; Danevich, F A; Decourt, R; Degoda, V Ya; Devoyon, L; Drillien, A; Dumoulin, L; Enss, C; Fleischmann, A; Gastaldo, L; Giuliani, A; Gros, M; Herve, S; Ivanov, I M; Kobychev, V V; Kogut, Ya P; Koskas, F; Loidl, M; Magnier, P; Makarov, E P; Mancuso, M; de Marcillac, P; Marnieros, S; Marrache-Kikuchi, C; Nasonov, S G; Navick, X F; Nones, C; Olivieri, E; Paul, B; Penichot, Y; Pessina, G; Plantevin, O; Poda, D V; Redon, T; Rodrigues, M; Strazzer, O; Tenconi, M; Torres, L; Tretyak, V I; Vasiliev, Ya V; Velazquez, M; Viraphong, O; Zhdankov, V N

    2013-01-01

    The LUMINEU program aims at performing a pilot experiment on neutrinoless double beta decay of 100Mo using radiopure ZnMoO4 crystals operated as scintillating bolometers. Growth of high quality radiopure crystals is a complex task, since there are no commercially available molybdenum compounds with the required levels of purity and radioactive contamination. This paper discusses approaches to purify molybdenum and synthesize compound for high quality radiopure ZnMoO4 crystal growth. A combination of a double sublimation (with addition of zinc molybdate) with subsequent recrystallization in aqueous solutions (using zinc molybdate as a collector) was used. Zinc molybdate crystals up to 1.5 kg were grown by the low-thermal-gradient Czochralski technique, their optical, luminescent, diamagnetic, thermal and bolometric properties were tested.

  19. Supported molybdenum carbide for higher alcohol synthesis from syngas

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Christensen, Jakob Munkholt; Chiarello, Gian Luca

    2013-01-01

    Molybdenum carbide supported on active carbon, carbon nanotubes, and titanium dioxide, and promoted by K2CO3, has been prepared and tested for methanol and higher alcohol synthesis from syngas. At optimal conditions, the activity and selectivity to alcohols (methanol and higher alcohols) over...... supported molybdenum carbide are significantly higher compared to the bulk carbide. The CO conversion reaches a maximum, when about 20wt% Mo2C is loaded on active carbon. The selectivity to higher alcohols increases with increasing Mo2C loading on active carbon and reaches a maximum over bulk molybdenum...... carbide, while the selectivity to methanol follows the opposite trend. The effect of Mo2C loading on the alcohol selectivity at a fixed K/Mo molar ratio of 0.14 could be related to the amount of K2CO3 actually on the active Mo2C phase and the size, structure and composition of the supported carbide...

  20. Molybdenum sputtering film characterization for high gradient accelerating structures

    Institute of Scientific and Technical Information of China (English)

    S.Bini; B.Spataro; A.Marcelli; S.Sarti; V.A.Dolgashev; S.Tantawi; A.D.Yeremian

    2013-01-01

    Technological advancements are strongly required to fulfill the demands of new accelerator devices with the highest accelerating gradients and operation reliability for the future colliders.To this purpose an extensive R&D regarding molybdenum coatings on copper is in progress.In this contribution we describe chemical composition,deposition quality and resistivity properties of different molybdenum coatings obtained via sputtering.The deposited films are thick metallic disorder layers with different resistivity values above and below the molibdenum dioxide reference value.Chemical and electrical properties of these sputtered coatings have been characterized by Rutherford backscattering,XANES and photoemission spectroscopy.We will also consider multiple cells standing wave section coated by a molybdenum layer designed to improve the performance of X-Band accelerating systems.

  1. Molybdenum removal from copper ore concentrate by sodium hypochlorite leaching

    Institute of Scientific and Technical Information of China (English)

    Liu Youcai; Zhong Hong; Cao Zhanfang

    2011-01-01

    The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time, liquid to solid ratio, leaching ternperature, agitation speed, and sodium hypochlorite and sodium hydroxide concentrations all have a significant effect on the removal of molybdenum. The optimum process operating parameters were found to be: time, 4 h: sodium hydroxide concentration, 10%; sodium hypochlorite concentration, 8%; liquid to solid ratio, 10:1; temperature, 50℃; and,agitation speed, 500 r/min. Under these conditions the extraction of molybdenum is greater than 99.9% and the extraction of copper is less than 0.01%. A shrinking particle model could be used to describe the leaching process. The apparent activation energy of the dissolution reaction was found to be approximately 8.8 kJ/mol.

  2. Adsorption behavior of molybdenum onto D314 ion exchange resin

    Institute of Scientific and Technical Information of China (English)

    王明玉; 蒋长俊; 王学文

    2014-01-01

    The adsorption behavior of molybdenum onto D314 was studied with the static adsorption method. The adsorption process was analyzed from thermodynamic and kinetic aspects. The experimental results show that the equilibrium adsorption data conform satisfactorily to the Langmuir equation. In the adsorption process of D314 for molybdenum, the enthalpy changeΔH is positive when temperature is in the range of 298−338 K, which indicates that the adsorption is an endothermic process, and the elevated temperature benefits to the adsorption. Kinetic analysis shows that the adsorption rate is controlled by intraparticle diffusion and chemical diffusion at the same time. The adsorption mechanism of molybdenum onto D314 was discussed based on IR spectra.

  3. Molybdenum sputtering film characterization for high gradient accelerating structures

    CERN Document Server

    Bini, S; Marcelli, A; Sarti, S; Dolgashev, V A; Tantawi, S; Yeremian, A D; Higashi, Y; Grimaldi, M G; Romano, L; Ruffino, F; Parodi, R; Cibin, G; Marrelli, C; Migliorati, M; Caliendo, C

    2012-01-01

    Technological advancements are strongly required to fulfill the demands of new accelerator devices with the highest accelerating gradients and operation reliability for the future colliders. To this purpose an extensive R&D regarding molybdenum coatings on copper is in progress. In this contribution we describe chemical composition, deposition quality and resistivity properties of different molybdenum coatings obtained via sputtering. The deposited films are thick metallic disorder layers with different resistivity values above and below the molibdenum dioxide reference value. Chemical and electrical properties of these sputtered coatings have been characterized by Rutherford backscattering, XANES and photoemission spectroscopy. We will also present a three cells standing wave section coated by a molybdenum layer $\\sim$ 500 nm thick designed to improve the performance of X-Band accelerating systems.

  4. The behaviour of molybdenum dialkyldithiocarbamate friction modifier additives

    CERN Document Server

    Graham, J C H

    2001-01-01

    In recent years there has been growing concern to produce energy-efficient lubricated components and modem engine oil specifications require lubricants to demonstrate fuel efficiency in standardised engine tests. One important method of producing low friction and thus fuel-efficient lubricants is to use oil-soluble, molybdenum-containing, friction modifier additives. In optimal conditions these additives are able to produce very low friction coefficients, in the range 0.045 to 0.075 in boundary lubrication conditions. Very little is known about the chemical and physical mechanisms by which oil soluble molybdenum additives form low friction films in tribological contacts. Information about their activity could lead to optimal use of these additives in lubricants and, therefore, more efficient engine running. The work outlined in this thesis investigated the behaviour of oil-soluble molybdenum additives and showed that these additives were able to effectively reduce friction in the absence of other additives su...

  5. Sulphate radical generation through interaction of peroxymonosulphate with Co(II) for in-line sample preparation aiming at spectrophotometric flow-based determination of phosphate and phosphite in fertilizers.

    Science.gov (United States)

    Crispino, Carla C; Kamogawa, Marcos Y; Ferreira, José R; Zagatto, Elias A G

    2016-09-01

    An advanced oxidative process relying on the interaction of peroxymonosulphate and cobalt(II) was implemented for generating the sulphate radicals in flow analysis, in order to accomplish in-line sample preparation thus improving the spectrophotometric determination of phosphate and phosphite in liquid foliar fertilizers. To this end, a flow-batch system with a heated chamber was designed. The sample was handled twice, with and without the step of phosphite oxidation to phosphate, and the formed orthophosphate was quantified after interaction with the vanadate-molybdate reagent. Phosphite was determined as the difference in analytical signals corresponding to sample handling with and without the oxidation step. Influence of Co(II) on the peroxymonosulphate activation, reagent concentrations and added volumes, acidity, temperature and heating time were investigated like aiming at to improve analytical recovery and measurement repeatability, as well as the and system ruggedness. The 6.6-20.0mgL(-1) P2O5 standards were in-line prepared from a single stock solution. Detection limits were estimated as 0.8 and 0.1mgL(-1) for P2O5 and P-PO4. Twenty-four samples are were run per hour, and results are were in agreement with those obtained by the official procedure.

  6. Complex chemistry with complex compounds

    Directory of Open Access Journals (Sweden)

    Eichler Robert

    2016-01-01

    Full Text Available In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the investigation of fragile single molecular species by gas-phase chromatography. The latest success with the heaviest group 6 transactinide seaborgium is highlighted. The formation of a very volatile hexacarbonyl compound Sg(CO6 was observed similarly to its lighter homologues molybdenum and tungsten. The interactions of these gaseous carbonyl complex compounds with quartz surfaces were investigated by thermochromatography. Second-generation experiments are under way to investigate the intramolecular bond between the central metal atom of the complexes and the ligands addressing the influence of relativistic effects in the heaviest compounds. Our contribution comprises some aspects of the ongoing challenging experiments as well as an outlook towards other interesting compounds related to volatile complex compounds in the gas phase.

  7. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at; Schmid, Ulrich, E-mail: ulrich.e366.schmid@tuwien.ac.at [Institute of Sensor and Actuator Systems, TU Wien, Gußhausstraße 27-29, A-1040 Vienna (Austria); Konrath, Jens Peter, E-mail: jenspeter.konrath@infineon.com; Haberl, Verena, E-mail: verena.haberl@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria)

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  8. Study on process mineralogy refractory molybdenum ore in Hebei province%河北某难选钼矿工艺矿物学研究

    Institute of Scientific and Technical Information of China (English)

    马驰; 卞孝东; 王守敬

    2013-01-01

    对河北某难选钼矿,通过光学显微镜、人工重砂、X射线衍射分析以及电子探针分析,确定了该矿主要矿物的组成及含量,详细研究了含钼矿物的化学成分和嵌布特征,以及钼的赋存状态,查清了该矿难选的原因.该矿性质复杂,氧化程度高,矿泥含量多,约71.2%的钼赋存在褐铁矿中.褐铁矿是钼的主要载体矿物,但是褐铁矿集合体多呈胶状、细脉-微细脉结构充填在矿石的裂隙、微裂隙中,粒度多在10um左右,这些不利于选矿富集.%There is a refractory molybdenum mine in Hebei province, Using a optical microscopy, manual artificial heavy concentrate, X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), molybdenum minerals and accompany minerals category and content of samples were studied, including chemical compositions, species, grain size, embedded characteristics, modes of occurrence of molybdenum minerals. ,and the reasons of this refractory molybdenum mine. This mine is complex mineral assemblages. Results also showed high oxidation rate of molybdenum and mudding degree. Perlimonite is the main carrier mineral of molybdenum,but the perlimonite collection which is filling in the fissures,micro-cracks of the ore show colloidal structure and veinlets structure The grain size of perlimonite is more about l0um. These are not conducive to dressing enrichment.

  9. Preparation and characterization of molybdenum disilicide coating on molybdenum substrate by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Dezhi, E-mail: dzwang68@163.com [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yan, Jianhui [Advanced Materials Synthesis and Application Technology Laboratory, Hunan University of Science and Technology, Xiangtan 411201 (China); Sun, Aokui [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2013-11-01

    MoSi{sub 2} oxidation protective coatings on molybdenum substrate were prepared by air plasma spraying technique (APS). Microstructure, phase composition, porosity, microhardness and bonding strength of the coatings were investigated and determined. Oxidation behavior of the coating at high temperature was also examined. Results show that composition of the coatings is constituted with MoSi{sub 2} and Mo{sub 5}Si{sub 3}, the surface morphology is described as flattened lamellar features, insufficiently flattened protuberance with some degree of surface roughness, a certain quantity of spherical particles, microcracks and pores. Testing results reveal that microhardness and bonding strength of the coatings increase, and porosity decreases with increasing power or decreasing Ar gas flow rate. Moreover, with decreasing the porosity, the microhardness of the coatings increases. The bonding strength of the coatings also increases with increasing spray distance. The MoSi{sub 2} coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

  10. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

  11. Corrosion Evaluation of RERTR Uranium Molybdenum Fuel

    Energy Technology Data Exchange (ETDEWEB)

    A K Wertsching

    2012-09-01

    As part of the National Nuclear Security Agency (NNSA) mandate to replace the use of highly enriched uranium (HEU) fuel for low enriched uranium (LEU) fuel, research into the development of LEU fuel for research reactors has been active since the late 1970’s. Originally referred to as the Reduced Enrichment for Research and Test Reactor (RERTR) program the new effort named Global Threat Reduction Initiative (GTRI) is nearing the goal of replacing the standard aluminum clad dispersion highly enriched uranium aluminide fuel with a new LEU fuel. The five domestic high performance research reactors undergoing this conversion are High Flux Isotope reactor (HFIR), Advanced Test Reactor (ATR), National Institute of Standards and Technology (NIST) Reactor, Missouri University Research Reactor (MURR) and the Massachusetts Institute of Technology Reactor II (MITR-II). The design of these reactors requires a higher neutron flux than other international research reactors, which to this point has posed unique challenges in the design and development of the new mandated LEU fuel. The new design utilizes a monolithic fuel configuration in order to obtain sufficient 235U within the LEU stoichoimetry to maintain the fission reaction within the domestic test reactors. The change from uranium aluminide dispersion fuel type to uranium molybdenum (UMo) monolithic configuration requires examination of possible corrosion issues associated with the new fuel meat. A focused analysis of the UMo fuel under potential corrosion conditions, within the ATR and under aqueous storage indicates a slow and predictable corrosion rate. Additional corrosion testing is recommended for the highest burn-up fuels to confirm observed corrosion rate trends. This corrosion analysis will focus only on the UMo fuel and will address corrosion of ancillary components such as cladding only in terms of how it affects the fuel. The calculations and corrosion scenarios are weighted with a conservative bias to

  12. Phosphite effect on hot and sweet pepper reaction to Phytophthora capsici Efeito do fosfito na reação de pimentão e pimenteira a Phytophthora capsici

    Directory of Open Access Journals (Sweden)

    Fernando Cesar Sala

    2004-10-01

    Full Text Available Phosphite has been recommended to enhance plant resistance against Phytophthora. This work evaluated the response of hot and sweet pepper (Capsicum annuum L. to Phytophthora capsici from juvenile up to the adult stage following treatment with phosphite. Sweet pepper hybrids considered to be resistant to P. capsici, like Reinger, Nathalie and Athenas, were evaluated. The susceptible checks were hybrid Magali R and cvs. Myr 10 and Ikeda. Hot pepper Criollo de Morelos 328, CM 334, BGH 3756, BGH 5122, CNPH 294 and Locorte were used as referential resistant lines. Phosphite did not have an effect on the hot pepper resistant lines because of their genetic homozygozity, while no protection was observed for the Athenas hybrid claimed to be resistant. Heterozygous hybrids recognized as resistant, like Reinger and Nathalie, showed higher survival following phosphite treatment, and their reaction was equivalent to the resistant cvs. CM 328 and CM 334, except for the fruiting stage. Depending of the hybrid heterozygous genotype, phosphite possibly acts through indirect phytoalexin induction through the inhibited pathogen.Fosfito tem sido recomendado para aumentar o sistema de resistência de plantas atacadas por fitopatógenos. Este trabalho avaliou a ação do fosfito nas reações de pimentão e pimenteiras (Capsicum annuum L. a Phytophthora capsici na fase juvenil até a fase adulta, tratadas com fosfito. Os híbridos de pimentão considerados resistentes a P. capsici foram Reinger, Nathalie e Athenas, enquanto que o híbrido Magali R e as cvs. Myr 10 e Ikeda constituíram as referenciais suscetíveis. As linhagens de pimenta Criollo de Morelos 328, CM 334, BGH 3756, BGH 5122, CNPH 294 e Locorte, foram usadas como padrão referencial de resistência ao patógeno. O fosfito não afetou a reação das linhagens resistentes devido sua homozigosidade genética. Não houve ação protetora do fosfito nos hospedeiros suscetíveis, inclusive no híbrido Athenas

  13. Directional uv photoemission from (100) and (110) molybdenum surfaces

    DEFF Research Database (Denmark)

    Cinti, R. C.; Khoury, E. Al; Chakraverty, B. K.;

    1976-01-01

    A study of the (100) and (110) molybdenum surfaces by directional photoemission spectroscopy is presented. Energy distribution spectra formed by photoelectrons emitted normal to the surfaces have been measured for photon energies between 10.2 and 21.2 eV. The results are discussed in terms of cal...

  14. Molybdenum incorporation in tungsten aldehyde oxidoreductase enzymes from Pyrococcus furiosus

    NARCIS (Netherlands)

    Sevcenco, A.M; Bevers, L.E.; Pinkse, M.W.H.; Krijger, G.C.; Wolterbeek, H.T.; Verhaert, P.D.E.M.; Hagen, W.R.; Hagedoorn, P.L.

    2010-01-01

    The hyperthermophilic archaeon Pyrococcus furiosus expresses five aldehyde oxidoreductase (AOR) enzymes, all containing a tungsto-bispterin cofactor. The growth of this organism is fully dependent on the presence of tungsten in the growth medium. Previous studies have suggested that molybdenum is no

  15. Femtosecond laser surface structuring of molybdenum thin films

    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, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Mthunzi, P. [Council for Scientific and Industrial Research (CSIR), Biophotonics Lab: National Laser Centre Pretoria, 0001 (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, Itala (Italy); Sechoghela, P.; Mongwaketsi, N. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Ramponi, R. [Institute for Photonics and Nanotechnologies (IFN)–CNR, Piazza Leanardo 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, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa)

    2015-10-30

    Highlights: • Color change of the molybdenum thin film from shinny to violet–yellowish color after laser irradiation at various laser powers. • Formation of the molybdenum dioxide coating after laser exposure, as confirmed by the X-ray diffraction spectrometry. • Selective solar absorbing nature of the laser exposed films. • Study of the binding energies is presented in this contribution using the XPS spectrometry. - Abstract: This contribution reports on the femtosecond surface structuring of molybdenum thin coatings deposited by electron beam evaporation onto Corning glass substrates. The 1-D type periodic grating lines created by such an ablation showed that the widths of the shallow grooves followed a logarithmic dependence with the laser energy incident on the molybdenum film. The electronic valence “x” of the created oxide surface layer MoO{sub x} was found to be incident laser power dependent via Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction investigations. Such a photo-induced MoO{sub x}–Mo nanocomposite exhibited effective selective solar absorption in the UV–vis–IR spectral range.

  16. GEMAS: Molybdenum Spatial Distribution Patterns in European Soil

    Science.gov (United States)

    Cicchella, Domenico; Zuzolo, Daniela; Demetriades, Alecos; De Vivo, Benedetto; Eklund, Mikael; Ladenberger, Anna; Negrel, Philippe; O'Connor, Patrick

    2017-04-01

    Molybdenum is an essential trace element for both plants and animals as well as for human being. It is one such trace element for which potential health concerns have been raised but for which few data exist and little investigation or interpretation of distributions in soils has been made. The main goal of this study was to fill this gap. Molybdenum (Mo) concentrations are reported for the governed by geology (parent material and mineralisation), as well as weathering, soil formation and climate since the last glaciations period. The dominant feature is represented by low Mo concentrations over the coarse-grained sandy deposits of the last glaciations in central northern Europe while the most extensive anomalies occur in Scandinavian soils. The highest Mo concentration value occurs to the North of Oslo close to one of the largest porphyry Mo deposit of the World. Some interesting anomalous patterns occur also in Italy in correspondence with alkaline volcanics, in Spain and Greece associated with sulfides mineralizations and in Slovenia and Croatia where are probably related to the long weathering history of karstic residual soils. Anomalous concentrations in some areas of Ireland represent a clear example of how an excess of molybdenum has produced potentially toxic pastures. In fact, these give rise to problems particularly in young cattle when excess molybdenum in the herbage acts as an antagonist, which militates against efficient copper absorption by the animal.

  17. Molybdenum incorporation in tungsten aldehyde oxidoreductase enzymes from Pyrococcus furiosus

    NARCIS (Netherlands)

    Sevcenco, A.M; Bevers, L.E.; Pinkse, M.W.H.; Krijger, G.C.; Wolterbeek, H.T.; Verhaert, P.D.E.M.; Hagen, W.R.; Hagedoorn, P.L.

    2010-01-01

    The hyperthermophilic archaeon Pyrococcus furiosus expresses five aldehyde oxidoreductase (AOR) enzymes, all containing a tungsto-bispterin cofactor. The growth of this organism is fully dependent on the presence of tungsten in the growth medium. Previous studies have suggested that molybdenum is no

  18. Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors.

    Science.gov (United States)

    Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini

    2016-07-18

    Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process.

  19. Research on the effect of phosphorus and molybdenum applications ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-05-02

    May 2, 2008 ... applications on the yield and yield parameters in lentil ... and from 6 g/kg seed molybdenum with 1231 kg ha-1 in the first year, the values were 80 kg ha-1 P with ... easier for the plant to benefit from the other nutritional.

  20. Preparation of isotopic molybdenum foils utilizing small quantities of material

    Science.gov (United States)

    Lipski, A. R.; Lee, L. L.; Liang, J. F.; Mahon, J. C.

    1993-09-01

    A simple method utilizing a small amount of isotopic material for production of molybdenum foils is discussed. An e-gun is used in the procedure. The Mo powder undergoes reduction-sintering and melting-solidifying steps leading to the creation of a metallic droplet suitable for further cold rolling or vacuum deposition.

  1. Synthesis and characterization of molybdenum incorporated mesoporous aluminophosphate

    Science.gov (United States)

    Ho, Li-Ngee; Ikegawa, Tasuku; Nishiguchi, Hiroyasu; Nagaoka, Katsutoshi; Takita, Yusaku

    2006-07-01

    A synthesis of molybdenum incorporated mesoporous aluminophosphate with long-chain n-alkylamine as template material had been prepared under non-aqueous condition. These materials were extensively characterized by using X-ray diffraction (XRD), nitrogen sorption isotherms, nuclear magnetic resonance of 27Al and 31P (NMR), inductive coupled plasma (ICP), electron spin resonance (ESR), Fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG-DTA). Morphology of the materials had been observed by using transmission electron microscope (TEM) that revealed the mesoporous materials possessed wormhole-like structures. Alkaline solvent extraction using n-butylamine/ethanol had been efficiently removed the n-alkylamine from the mesoporous samples which yielded BET surface areas around 550-730 m 2/g. BJH analysis showed a narrow pore size distribution which increased with increasing of the carbon chain length of alkylamine (template). Valence state and coordination of the molybdenum in the obtained samples were investigated by using ESR and FTIR where it was found that Mo 4+ and Mo 6+ molybdenum species existed in the molybdenum incorporated mesoporous aluminophosphate in tetrahedral coordination.

  2. A chemical approach toward low temperature alloying of immiscible iron and molybdenum metals

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Applied Chemistry Research Centre, Pakistan Council of Scientific and Industrial Research Laboratories Complex, Lahore 54600 (Pakistan); Ahmed, Sohail [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad, E-mail: mazhar42pk@yahoo.com [Department of Chemistry, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Akhtar, Muhammad Javed; Siddique, Muhammad [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Khan, Nawazish Ali [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shah, Muhammad Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Nadeem, Muhammad [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2013-11-15

    Graphical abstract: - Highlights: • Low temperature pyrolysis of [Fe(bipy){sub 3}]Cl{sub 2} and [Mo(bipy)Cl{sub 4}] homogeneous powder. • Easy low temperature alloying of immiscible metals like Fe and Mo. • Uniform sized Fe–Mo nanoalloy with particle size of 48–68 nm. • Characterization by EDXRF, AFM, XRPD, magnetometery, {sup 57}Fe Mössbauer and impedance. • Alloy behaves as almost superparamagnetic obeying simple –R(CPE)– circuit. - Abstract: The present research is based on a low temperature operated feasible method for the synthesis of immiscible iron and molybdenum metals’ nanoalloy for technological applications. The nanoalloy has been synthesized by pyrolysis of homogeneous powder precipitated, from a common solvent, of the two complexes, trisbipyridineiron(II)chloride, [Fe(bipy){sub 3}]Cl{sub 2}, and bipyridinemolybedenum(IV) chloride, [Mo(bipy)Cl{sub 4}], followed by heating at 500 °C in an inert atmosphere of flowing argon gas. The resulting nanoalloy has been characterized by using EDXRF, AFM, XRD, magnetometery, {sup 57}Fe Mössbauer and impedance spectroscopies. These results showed that under provided experimental conditions iron and molybdenum metals, with known miscibility barrier, alloy together to give (1:1) single phase material having particle size in the range of 48–66 nm. The magnetism of iron is considerably reduced after alloy formation and shows its trend toward superparamagnetism. The designed chemical synthetic procedure is equally feasible for the fabrication of other immiscible metals.

  3. Comparison between the effects of potassium phosphite and chitosan on changes in the concentration of Cucurbitacin E and on antibacterial property of Cucumis sativus.

    Science.gov (United States)

    Ramezani, Moazzameh; Rahmani, Fatemeh; Dehestani, Ali

    2017-06-05

    Cucurbitacins are mostly found in the members of the family Cucurbitaceae and are responsible for the bitter taste of cucumber. Pharmacological activities such as anti-bacterial and anti-tumor effects have been attributed to these structurally divers triterpens. The aim of this study was to investigate the effect of potassium phosphite (KPhi) and chitosan on Cucurbitacin E (CuE) concentration in different tissues of Cucumis sativus. The antibacterial effect of plant ethanolic extracts was also examined against E.coli PTCC 1399 and Pseudomonas aeruginosa PTCC 1430 bacterial strains. After emergence of secondary leaves, cucumber plants were divided into 4 groups (each group consisted of 6 pots and each pot contained one plant) and different treatments performed as follows: group1. Leaves were sprayed with distilled water (Control), group 2. The leaves were solely treated with potassium phosphite (KPhi), group 3. Leaves were solely sprayed with chitosan (Chitosan), group 4. Leaves were treated with KPhi and chitosan (KPhi + chitosan). The KPhi (2 g L(-1)) and chitosan (0.2 g L(-1)) were applied twice every 12 h for one day. Fruits, roots and leaves were harvested 24 h later. The ethanolic extract of plant organs was used for determination of CuE concentration using HPLC approach. The antimicrobial activity was evaluated by the agar well diffusion method. The experiments were arranged in a completely randomized design (CRD) and performed in six biological replications for each treatment. Analysis of variance was performed by one-way ANOVA and Dunnette multiple comparison using SPSS. The highest level of CuE was recorded in fruit (2.2 g L(-1)) of plants under concomitant applications of KPhi and chitosan. Result of antibacterial activity evaluation showed that under concomitant treatments of KPhi and chitosan, fruit extract exhibited the highest potential for activity against E. coli PTCC 1399 (with mean zone of inhibition equal to 36 mm) and Pseudomonas

  4. Cloud-point preconcentration and spectrophotometric determination of trace amounts of molybdenum(VI) in steels and water samples.

    Science.gov (United States)

    Madrakian, Tayyebeh; Ghazizadeh, Fariba

    2008-05-01

    A cloud-point extraction process using micelle of the cationic surfactant CTAB to extract Mo(VI) from aqueous solutions was investigated. The method is based on the color reaction of molybdenum with bromopyrogallol red in the presence of potassium iodide at pH 1.0 glycine/HCl buffer media and micelle-mediated extraction of complex. The optimal extraction and reaction conditions (e.g., surfactant concentration, reagent concentration and effect of time) were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration and improvement factors) were obtained. Linearity was obeyed in the range of 0.3-320.0 ng mL(-1) of molybdenum(VI) ion and the detection limit of the method was 0.1 ng mL(-1). The relative standard deviation (R.S.D.) and relative error for five replicate measurements of 65.0 ng mL(-1) Mo(VI) were 1.1% and 1.9%, respectively. The interference effect of some anions and cations was also tested. The method was applied to the determination of molybdenum(VI) in steels and tap water and well water samples.

  5. Determination of molybdenum in plants by vortex-assisted emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Oviedo, Jenny A.; Fialho, Lucimar L.; Nóbrega, Joaquim A., E-mail: djan@terra.com.br

    2013-08-01

    A fast and sensitive procedure for extraction and preconcentration of molybdenum in plant samples based on solidified floating organic drop microextraction combined with flame atomic absorption spectrometry and discrete nebulization was developed. 8-Hydroxyquinoline (8-HQ) was used as complexing agent. The experimental conditions established were: 0.5% m v{sup −1} of 8-HQ, 60 μL of 1-undecanol as the extractant phase, 2 min vortex extraction time, centrifugation for 2 min at 2000 rpm, 10 min into an ice bath and discrete nebulization by introducing 200 μL of solution. The calibration curve was linear from 0.02 to 4.0 mg L{sup −1} with a limit of detection of 4.9 μg L{sup −1} and an enhancement factor of 67. The relative standard deviations for ten replicate measurements of 0.05 and 1.0 mg L{sup −1} Mo were 6.0 and 14.5%, respectively. The developed procedure was applied for determining molybdenum in corn samples and accuracy was proved using certified reference materials. - Highlights: ► Molybdenum was determined in plants by flame AAS. ► Flame AAS sensitivity was improved using microextraction and discrete nebulization. ► The developed procedure can be easily implemented in routine analysis. ► Green chemistry principles are followed.

  6. Cloud-point preconcentration and spectrophotometric determination of trace amounts of molybdenum(VI) in steels and water samples

    Energy Technology Data Exchange (ETDEWEB)

    Madrakian, Tayyebeh [Faculty of Chemistry, Bu-Ali Sina University, Hamadan (Iran, Islamic Republic of)], E-mail: madrakian@basu.ac.ir; Ghazizadeh, Fariba [Faculty of Chemistry, Bu-Ali Sina University, Hamadan (Iran, Islamic Republic of)

    2008-05-01

    A cloud-point extraction process using micelle of the cationic surfactant CTAB to extract Mo(VI) from aqueous solutions was investigated. The method is based on the color reaction of molybdenum with bromopyrogallol red in the presence of potassium iodide at pH 1.0 glycine/HCl buffer media and micelle-mediated extraction of complex. The optimal extraction and reaction conditions (e.g., surfactant concentration, reagent concentration and effect of time) were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration and improvement factors) were obtained. Linearity was obeyed in the range of 0.3-320.0 ng mL{sup -1} of molybdenum(VI) ion and the detection limit of the method was 0.1 ng mL{sup -1}. The relative standard deviation (R.S.D.) and relative error for five replicate measurements of 65.0 ng mL{sup -1} Mo(VI) were 1.1% and 1.9%, respectively. The interference effect of some anions and cations was also tested. The method was applied to the determination of molybdenum(VI) in steels and tap water and well water samples.

  7. Interaction of Tryptophane and Phenylalanine with Cadmium and Molybdenum Ferrocyanides and Its Implications in Chemical Evolution and Origins of Life.

    Science.gov (United States)

    Tewari, Brij

    2016-07-01

    Insoluble metal hexacyanoferrate(II) complexes could have concentrated biomonomers from dilute prebiotic soup during course of chemical evolution and origin of life or primitive earth. In the light of above hypothesis, adsorption of tryptophane and phenylalanine was studied on cadmium and molybdenum ferrocyanides at neutral pH (7.0 ± 0.01) and at a temperature of 30 ± 1º C. Interaction of amino acids with metal ferrocyanides are found to be maximum at neutral pH. Neutral pH is chosen for the adsorption studies because most of the reactions in biological systems taken place at neutral pH range. Adsorption trend follow Langmuir isotherm model. The Langmuir constants b and Qo were calculated at neutral pH, tryptophane was found to more adsorbed than phenylalanine on both metal ferrocyanides studied. Molybdenum ferrocyanides studied. Molybdenum ferrocyanides was found to have more uptake capacity for both adsorbates than cadmium ferrocyanides. The present study suggests that metal ferrocyanides might have played a role in the stabilization of biomolecules through their surface activity during course of chemical solution and origins of life on primitive earth.

  8. In-situ molybdenum nano-attached particle synthesis from spent Mo scrap.

    Science.gov (United States)

    Han, Chulwoong; Kim, Byungmoon; Choi, Hanshin

    2014-10-01

    Radio frequency thermal plasma is a versatile process for engineering powder preparation owing to its high energy density and reactivity. Molybdenum powders were prepared from molybdenum sheet scrap by RF thermal plasma in association with powder comminution process. Molybdenum scrap which was used in high temperature environment was friable enough to be broken into micropowders by hammer milling. Spherical molybdenum micro-powder was obtained from the hammer milled powders were treated via thermal plasma. On the other hand, vaporization and condensation pathway for nanoparticle synthesis is largely dependent on both thermo-physical properties and thermal plasma properties. In this regard, molybdenum trioxide was chosen for the feedstock of nanoparticle synthesis. Additional reactivity of argon-hydrogen thermal plasma, oxide feedstock was fully reduced to bcc molybdenum. Considering different reaction pathway of each feedstock, molybdenum nanoparticle attached molybdenum spherical micro-powder could be effectively synthesized by feeding a blended feedstock of molybdenum micro-powder and molybdenum trioxide micro-powder into argon-hydrogen thermal plasma.

  9. Use of long-chain alkylamines for preconcentration and determination of traces of molybdenum, tungsten and rhenium by atomic-absorption spectroscopy-II: molybdenum in soils, sediments and natural waters.

    Science.gov (United States)

    Kim, C H; Alexander, P W; Smythe, L E

    1976-03-01

    Molybdenum is extracted as the thiocyanate complex with the quaternary long-chain aliphatic amine Aliquat 336 in chloroform, followed by evaporation of the solvent, dissolution in MIBK, and atomic-absorption spectroscopy. The method is simple, rapid and sensitive, with few interference problems for the determination of the Mo content of soils and sediments in the range 0.1-1.0 ppm with a relative standard deviation better than 5% when 1-g samples are used. Quantitative extraction from large volumes of aqueous solution has also been confirmed, allowing the determination of Mo in natural waters in the ppM range.

  10. Molybdenum isotope fractionation in the mantle

    Science.gov (United States)

    Liang, Yu-Hsuan; Halliday, Alex N.; Siebert, Chris; Fitton, J. Godfrey; Burton, Kevin W.; Wang, Kuo-Lung; Harvey, Jason

    2017-02-01

    We report double-spike molybdenum (Mo) isotope data for forty-two mafic and fifteen ultramafic rocks from diverse locations and compare these with results for five chondrites. The δ98/95Mo values (normalized to NIST SRM 3134) range from -0.59 ± 0.04 to +0.10 ± 0.08‰. The compositions of one carbonaceous (CI) and four ordinary chondrites are relatively uniform (-0.14 ± 0.01‰, 95% ci (confidence interval)) in excellent agreement with previous data. These values are just resolvable from the mean of 10 mid-ocean ridge basalts (MORBs) (0.00 ± 0.02‰, 95% ci). The compositions of 13 mantle-derived ultramafic xenoliths from Kilbourne Hole, Tariat and Vitim are more diverse (-0.39 to -0.07‰) with a mean of -0.22 ± 0.06‰ (95% ci). On this basis, the isotopic composition of the bulk silicate Earth (BSE or Primitive Mantle) is within error identical to chondrites. The mean Mo concentration of the ultramafic xenoliths (0.19 ± 0.07 ppm, 95% ci) is similar in magnitude to that of MORB (0.48 ± 0.13 ppm, 95% ci), providing evidence, either for a more compatible behaviour than previously thought or for selective Mo enrichment of the subcontinental lithospheric mantle. Intraplate and ocean island basalts (OIBs) display significant isotopic variability within a single locality from MORB-like to strongly negative (-0.59 ± 0.04‰). The most extreme values measured are for nephelinites from the Cameroon Line and Trinidade, which also have anomalously high Ce/Pb and low Mo/Ce relative to normal oceanic basalts. δ98/95Mo correlates negatively with Ce/Pb and U/Pb, and positively with Mo/Ce, explicable if a phase such as an oxide or a sulphide liquid selectively retains isotopically heavy Mo in the mantle and fractionates its isotopic composition in low degree partial melts. If residual phases retain Mo during partial melting, it is possible that the [Mo] for the BSE may be misrepresented by values estimated from basalts. This would be consistent with the high Mo

  11. Effect of molybdenum on the microstructure and wear resistance of Fe-based hardfacing coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.H. [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)], E-mail: xinhongwang@sdu.edu.cn; Han, F. [Department of Mechanical and Electrical Engineering, College of Weifang, Weifang 261021 (China); Liu, X.M.; Qu, S.Y.; Zou, Z.D. [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

    2008-08-20

    Fe-based hardfacing alloys containing molybdenum compound have been deposited on AISI 1020 steel substrates by shield manual arc welding (SMAW) process. The effect of Mo on the microstructure and wear resistance of the Fe-based hardfacing alloys were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis, as well as wear test. The results indicated that cuboidal and rod-type complex carbides were synthesized in the lath martensite matrix. The fraction of carbides in hardfacing layer increased with an increasing of Mo content. The hardfacing layer with good cracking resistance and wear resistance could be obtained when the amounts of Fe-Mo was controlled within a range of 3-4 wt.%. The improvement of hardness and wear resistance of the hardfacing layers attributed to the formation of Mo{sub 2}C carbide and the solution strengthening of Mo.

  12. Quantum transport model for zigzag molybdenum disulfide nanoribbon structures : A full quantum framework

    Directory of Open Access Journals (Sweden)

    Chun-Nan Chen

    2016-08-01

    Full Text Available Mainly based on non-equilibrium Green’s function technique in combination with the three-band model, a full atomistic-scale and full quantum method for solving quantum transport problems of a zigzag-edge molybdenum disulfide nanoribbon (zMoSNR structure is proposed here. For transport calculations, the relational expressions of a zMoSNR crystalline solid and its whole device structure are derived in detail and in its integrity. By adopting the complex-band structure method, the boundary treatment of this open boundary system within the non-equilibrium Green’s function framework is so straightforward and quite sophisticated. The transmission function, conductance, and density of states of zMoSNR devices are calculated using the proposed method. The important findings in zMoSNR devices such as conductance quantization, van Hove singularities in the density of states, and contact interaction on channel are presented and explored in detail.

  13. Synthesis and characterization of new magnetically recoverable molybdenum nanocatalyst for epoxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Masteri-Farahani, M., E-mail: mfarahany@yahoo.com [Faculty of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Kashef, Z. [Faculty of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of)

    2012-04-15

    New heterogeneous molybdenum catalyst was prepared through covalent attachment of a Schiff base ligand on the surface of silica coated magnetite nanoparticles via aminopropyl spacer and subsequent complexation with MoO{sub 2}(acac){sub 2}. The prepared nanocatalyst was characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies and vibrating sample magnetometry. Catalytic epoxidation of some olefins and allylic alcohols by prepared nanocatalyst using tert-butyl hydroperoxide and cumene hydroperoxide as oxidants was achieved with good activities and selectivities. - Highlights: Black-Right-Pointing-Pointer Silica coated magnetite nanoparticles were modified with a Schiff base ligand. Black-Right-Pointing-Pointer Next reaction with MoO{sub 2}(acac){sub 2} afforded magnetically recoverable nanocatalyst. Black-Right-Pointing-Pointer The prepared nanocatalyst catalyzed the epoxidation of olefins with TBHP.

  14. Molecular molybdenum persulfide and related catalysts for generating hydrogen from water

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; Chang, Christopher J.; Karunadasa, Hemamala I.; Majda, Marcin

    2016-11-22

    New metal persulfido compositions of matter are described. In one embodiment the metal is molybdenum and the metal persulfido complex mimics the structure and function of the triangular active edge site fragments of MoS.sub.2, a material that is the current industry standard for petroleum hydro desulfurization, as well as a promising low-cost alternative to platinum for electrocatalytic hydrogen production. This molecular [(PY5W.sub.2)MoS.sub.2].sup.x+ containing catalyst is capable of generating hydrogen from acidic-buffered water or even seawater at very low overpotentials at a turnover frequency rate in excess of 500 moles H.sub.2 per mole catalyst per second, with a turnover number (over a 20 hour period) of at least 19,000,000 moles H.sub.2 per mole of catalyst.

  15. Molecular molybdenum persulfide and related catalysts for generating hydrogen from water

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; Chang, Christopher J.; Karunadasa, Hemamala I.; Majda, Marcin

    2016-04-19

    New metal persulfido compositions of matter are described. In one embodiment the metal is molybdenum and the metal persulfido complex mimics the structure and function of the triangular active edge site fragments of MoS.sub.2, a material that is the current industry standard for petroleum hydro desulfurization, as well as a promising low-cost alternative to platinum for electrocatalytic hydrogen production. This molecular [(PY5W.sub.2)MoS.sub.2].sup.x+ containing catalyst is capable of generating hydrogen from acidic-buffered water or even seawater at very low overpotentials at a turnover frequency rate in excess of 500 moles H.sub.2 per mole catalyst per second, with a turnover number (over a 20 hour period) of at least 19,000,000 moles H.sub.2 per mole of catalyst.

  16. Solvent extraction and photometric determination of molybdenum (VI) with 2-aminobenzenethiol.

    Science.gov (United States)

    Chakrabarti, A K; Bag, S P

    1976-10-01

    A new extractive photometric method is described for estimation of molybdenum with 2-aminobenzenethiol. The green complex in chloroform has its absorbance maximum at 700 nm and is stable for 2 hr when extracted from a solution of optimum pH range 1.4-2.8. The extraction is quantitative. The sensitivity is 0.0075 microg cm (2). Beer's law is obeyed over the range 0.25-10 ppm with optimum range 0.5-4.5 ppm. The molar absorptivity is 7.08 x 10(4) 1.mole(-1). cm(-1). The overall stability constant is 2.0 x 10(8) at 25 +/- 0.1 degrees.

  17. In situ hydrogenation of molybdenum oxide nanowires for enhanced supercapacitors

    KAUST Repository

    Shakir, Imran

    2014-01-01

    In situ hydrogenation of orthorhombic molybdenum trioxide (α-MoO 3) nanowires has been achieved on a large scale by introducing alcohol during the hydrothermal synthesis for electrochemical energy storage supercapacitor devices. The hydrogenated molybdenum trioxide (H xMoO3) nanowires yield a specific capacitance of 168 F g-1 at 0.5 A g-1 and maintain 108 F g-1 at 10 A g-1, which is 36-fold higher than the capacitance obtained from pristine MoO3 nanowires at the same conditions. The electrochemical devices made with HxMoO3 nanowires exhibit excellent cycling stability by retaining 97% of their capacitance after 3000 cycles due to an enhanced electronic conductivity and increased density of hydroxyl groups on the surface of the MoO3 nanowires. This journal is © The Royal Society of Chemistry.

  18. Induction plasma spheroidization of tungsten and molybdenum powders

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.

  19. Cranial ultrasound and chronological changes in molybdenum cofactor deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Mercedes; Dias, Anna P.; Perez-Duenas, Belen; Campistol, Jaume; Garcia-Cazorla, Angels [Hospital Sant Joan de Deu, Department of Pediatric Neurology, Paseo de Sant Joan de Deu, Barcelona (Spain); Lizarraga, Isabel [Hospital Sant Joan de Deu, Department of Neonatology, Barcelona (Spain); Reiss, Jochen [University of Goettingen, Institute for Human Genetics, Goettingen (Germany); Vilaseca, Maria A.; Artuch, Rafael [Hospital Sant Joan de Deu, Clinical Biochemistry Department, Barcelona (Spain)

    2007-10-15

    Molybdenum cofactor is essential for the function of three human enzymes: sulphite oxidase, xanthine dehydrogenase, and aldehyde oxidase. Molybdenum cofactor deficiency is a rare autosomal recessively inherited disease. Disturbed development and damage to the brain may occur as a result of accumulation of toxic levels of sulphite. The CT and MRI findings include severe early brain abnormalities and have been widely reported, but the cranial US imaging findings have seldom been reported. We report a chronological series of cranial US images obtained from an affected infant that show the rapid development of cerebral atrophy, calcifications and white matter cysts. Our report supports the utility of cranial US, a noninvasive bed-side technique, in the detection and follow-up of these rapidly changing lesions. (orig.)

  20. The Structure and Stability of Molybdenum Ditelluride Thin Films

    Directory of Open Access Journals (Sweden)

    Zhouling Wang

    2014-01-01

    Full Text Available Molybdenum-tellurium alloy thin films were fabricated by electron beam evaporation and the films were annealed in different conditions in N2 ambient. The hexagonal molybdenum ditelluride thin films with well crystallization annealed at 470°C or higher were obtained by solid state reactions. Thermal stability measurements indicate the formation of MoTe2 took place at about 350°C, and a subtle weight-loss was in the range between 30°C and 500°C. The evolution of the chemistry for Mo-Te thin films was performed to investigate the growth of the MoTe2 thin films free of any secondary phase. And the effect of other postdeposition treatments on the film characteristics was also investigated.

  1. Production of Molybdenum-99 using Neutron Capture Methods

    Energy Technology Data Exchange (ETDEWEB)

    Toth, James J; Greenwood, Lawrence R; Soderquist, Chuck Z; Wittman, Richard S; Pierson, Bruce D; Burns, Kimberly A; Lavender, Curt A; Painter, Chad L; Love, Edward F; Wall, Donald E

    2011-01-01

    Pacific Northwest National Laboratory (PNNL), operated by Battelle, has identified a reference process for the production of molybdenum-99 (99Mo) for use in a chromatographic generator to separate the daughter product, technetium-99m (99mTc). The reference process uses the neutron capture reaction of natural or enriched molybdenum oxide via the reaction 98Mo(n,γ)99Mo. The irradiated molybdenum is dissolved in an alkaline solution, whereby the molybdenum, dissolved as the molybdate anion, is loaded on a proprietary ion exchange material in the chromatographic generator. The approach of this investigation is to provide a systematic collection of technologies to make the neutron capture method for Mo-99 production economically viable. This approach would result in the development of a technetium Tc99m generator and a new type of target. The target is comprised of molybdenum, either natural or enriched, and is tailored to the design of currently operating U.S. research reactors. The systematic collection of technologies requires evaluation of new metallurgical methods to produce the target, evaluation of target geometries tailored to research reactors, and chemical methods to dissolve the irradiated target materials for use in a chromatographic generator. A Technical specification for testing the target and neutron capture method in a research reactor is also required. This report includes identification of research and demonstration activities needed to enable deployment of neutron capture production method, including irradiations of prototypic targets, chemical processing of irradiated targets, and loading and extraction tests of Mo99 and Tc99m on the sorbent material in a prototypic generator design. The prototypical generator design is based on the proprietary method and systems for isotope product generation. The proprietary methods and systems described in this report are clearly delineated with footnotes. Ultimately, the Tc-99m generator solution provided by

  2. Control of wheat diseases using phosphites and acibenzolar-s-methyl alone or associated with piraclostrobina + epoxiconazoleControle de doenças do trigo com fosfitos e acibenzolar-s-metil isoladamente ou associados a piraclostrobina + epoxiconazole

    Directory of Open Access Journals (Sweden)

    Olavio Correa Silva

    2011-07-01

    Full Text Available The objective of this study was to evaluate the effect of different sources of phosphite to control leaf rust, powdery mildew, yellow and brown spot in the wheat crop in Palmeira, Paraná state, Brazil. The treatments were: four commercial sources of phosphites (A, B, C and D, applied at 1500 mL ha-1, (applied in rate of active product acibenzolar-S-methyl (ASM at 500 mL ha-1 (isolad or association, pyraclostrobin + epoxiconazole (fungicide at 400 mL ha-1 and phosphite A with pyraclostrobin + epoxiconazole (at 300 mL ha-1, phosphite A with pyraclostrobin + epoxiconazole (400 mL ha-1, acibenzolar-S-methyl with pyraclostrobin + epoxiconazole (400 mL ha-1 and control (water, . The experimental design adopted was complete randomized blocks with four replications. Regarding diseases, evaluations were done on the determination of severity and the calculation of the area below the curve of the disease progress in the flag leaf and entire plant. Leaf area index, thousand seeds weight, hectoliter weight and yield were also evaluated. Phosphite, independently source, did not act on leaf rust, powdery mildew, yellow and brown spot. The resistance inducer acibenzolar-S-methyl either isolated or associated to other fungicides affected leaf rust and powdery mildew of the wheat. Only phosphites associated to the fungicide controlled diseases, however there was no additional increase in yield whether compared to the control promoted by the fungicide.Foi realizado um experimento no município de Palmeira-PR, visando avaliar o efeito de diferentes fontes de fosfitos no controle da ferrugem da folha, do oídio e das manchas amarela e marrom na cultura do trigo. Os tratamentos foram: quatro fontes comerciais de fosfitos (A, B, C e D aplicados na dose de 1500 mL ha-1 (dose de produto ativo isolado ou associado aos demais produtos, acibenzolar-S-metil (ASM na dose de 500 mL ha-1 (isolado ou associado, piraclostrobina + epoxiconazole (fungicida na dose de 500 mL ha-1

  3. Concentrations of boron, molybdenum, and selenium in chinook salmon

    Science.gov (United States)

    Hamilton, Steven J.; Wiedmeyer, Raymond H.

    1990-01-01

    The concentrations of boron, molybdenum, and selenium in young chinook salmon Oncorhynchus tshawytscha were determined in three partial life cycle chronic toxicity studies. In each study, fish were exposed to a mixture of boron, molybdenum, selenate, and selenite in the proportions found in subsurface agricultural drainage water in the basin of the San Joaquin Valley, California. Tests were conducted in well water and in site-specific fresh and brackish waters. No boron or molybdenum was detected in fish exposed to concentrations as high as 6,046 μg boron/L and 193 μg molybdenum/L for 90 d in well water or fresh water; however, whole-body concentrations of selenium increased with increasing exposure concentrations in well water and fresh water, but not in brackish water. Concentrations of selenium in chinook salmon were strongly correlated with reduced survival and growth of fish in well water and with reduced survival in a 15-d seawater challenge test of fish from fresh water. Concentrations of selenium in fish seemed to reach a steady state after 60 d of exposure in well water or fresh water. Fish in brackish water had only background concentrations of selenium after 60 d of exposure, and no effects on survival and growth in brackish water or on survival in a 10-d seawater challenge test were exhibited. This lack of effect in brackish water was attributed to initiation of the study with advanced fry, which were apparently better able to metabolize the trace element mixture than were the younger fish used in studies with well water and fresh water. In all three experimental waters, concentration factors (whole-body concentration/waterborne concentration) for selenium decreased with increasing exposure concentrations, suggesting decreased uptake or increased excretion, or both, of selenium at the higher concentrations.

  4. Bulk molybdenum field emitters by inductively coupled plasma etching.

    Science.gov (United States)

    Zhu, Ningli; Cole, Matthew T; Milne, William I; Chen, Jing

    2016-12-07

    In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realised for masks consisting of aperture arrays some 4.45 μm in diameter and whose field electron emission performance has been herein assessed.

  5. Molybdenum work function determined by electron emission microscopy.

    Science.gov (United States)

    Jacobson, D. L.; Campbell, A. E.

    1971-01-01

    A polycrystalline molybdenum sample was recrystallized and thermally stabilized. Quantitative measurements of the emission from each individual grain were obtained with an electron emission microscope. The effective work function for each grain was then calculated. The crystallographic orientation of each grain was determined by Laue back-reflection techniques. A polar plot of effective work function vs crystallographic orientation for the sample was constructed to provide a correlation between effective work function and crystallographic orientation.

  6. Structural properties of molybdenum-lead-borate glasses

    Science.gov (United States)

    Rada, M.; Rada, S.; Pascuta, P.; Culea, E.

    2010-11-01

    Glasses and glass ceramics in the system xMoO 3·(100 - x)[3B 2O 3·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO 3] units containing non-bridging oxygens and [MoO 4] 2- molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO 4 crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO 6] and [Mo 2O 7] structural units. Pb 2+ ions with 6s 2 configuration show strong absorption in the ultraviolet due to parity allowed s 2-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ˜ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo 6+ to the Mo 5+ and Mo 4+ to the Mo 3+ states.

  7. Molybdenum Carbide Synthesis Using Plasmas for Fuel Cells

    Science.gov (United States)

    2013-06-01

    THIS PAGE INTENTIONALLY LEFT BLANK i REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704–0188 Public reporting burden for this collection of...per Minute H Hydrogen H2 Hydrogen Gas H2S Hydrogen Sulfide K Kelvin kV Kilovolt KeV Kilo Electron Volt LANL Los Alamos National Lab MeV Mega...solve the durability issues. While conducting research into molybdenum nitrides, scientists at Los Alamos National Lab ( LANL ) recently discovered

  8. Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum.

    Science.gov (United States)

    Lotfi, Samira; Boffito, Daria C; Patience, Gregory S

    2015-10-26

    Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the β-O-4 and 5-5' linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600 K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25 % selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride.

  9. The ineluctable requirement for the trans-iron elements molybdenum and/or tungsten in the origin of life

    Science.gov (United States)

    Schoepp-Cothenet, Barbara; van Lis, Robert; Philippot, Pascal; Magalon, Axel; Russell, Michael J.; Nitschke, Wolfgang

    2012-02-01

    An evolutionary tree of key enzymes from the Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily distinguishes ``ancient'' members, i.e. enzymes present already in the last universal common ancestor (LUCA) of prokaryotes, from more recently evolved subfamilies. The majority of the presented subfamilies and, as a consequence, the Molybdo-enzyme superfamily as a whole, appear to have existed in LUCA. The results are discussed with respect to the nature of bioenergetic substrates available to early life and to problems arising from the low solubility of molybdenum under conditions of the primordial Earth.

  10. Feasibility of preparing patterned molybdenum coatings on bismuth telluride thermoelectric modules.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Hall, Aaron Christopher; Miller, Stephen Samuel; Knight, Marlene E.; LePage, William S.; Sobczak, Catherine Elizabeth.; Wesolowski, Daniel Edward

    2013-09-01

    Molybdenum electrical interconnects for thermoelectric modules were produced by air plasma spraying a 30%CE%BCm size molybdenum powder through a laser-cut Kapton tape mask. Initial feasibility demonstrations showed that the molybdenum coating exhibited excellent feature and spacing retention (~170%CE%BCm), adhered to bismuth-telluride, and exhibited electrical conductivity appropriate for use as a thermoelectric module interconnect. A design of experiments approach was used to optimize air plasma spray process conditions to produce a molybdenum coating with low electrical resistivity. Finally, a molybdenum coating was successfully produced on a fullscale thermoelectric module. After the addition of a final titanium/gold layer deposited on top of the molybdenum coating, the full scale module exhibited an electrical resistivity of 128%CE%A9, approaching the theoretical resistivity value for the 6mm module leg of 112%CE%A9. Importantly, air plasma sprayed molybdenum did not show significant chemical reaction with bismuth-telluride substrate at the coating/substrate interface. The molybdenum coating microstructure consisted of lamellar splats containing columnar grains. Air plasma sprayed molybdenum embedded deeply (several microns) into the bismuth-telluride substrate, leading to good adhesion between the coating and the substrate. Clusters of round pores (and cracks radiating from the pores) were found immediately beneath the molybdenum coating. These pores are believed to result from tellurium vaporization during the spray process where the molten molybdenum droplets (2623%C2%B0C) transferred their heat of solidification to the substrate at the moment of impact. Substrate cooling during the molybdenum deposition process was recommended to mitigate tellurium vaporization in future studies.

  11. Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium

    Directory of Open Access Journals (Sweden)

    S. A. Ahmad

    2013-01-01

    Full Text Available A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue. Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.

  12. Molybdate reduction to molybdenum blue by an Antarctic bacterium.

    Science.gov (United States)

    Ahmad, S A; Shukor, M Y; Shamaan, N A; Mac Cormack, W P; Syed, M A

    2013-01-01

    A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo⁶⁺ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.

  13. Bandgap tunability at single-layer molybdenum disulphide grain boundaries

    KAUST Repository

    Huang, Yu Li

    2015-02-17

    Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85±0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

  14. Basic ammonothermal GaN growth in molybdenum capsules

    Science.gov (United States)

    Pimputkar, S.; Speck, J. S.; Nakamura, S.

    2016-12-01

    Single crystal, bulk gallium nitride (GaN) crystals were grown using the basic ammonothermal method in a high purity growth environment created using a non-hermetically sealed molybdenum (Mo) capsule and compared to growths performed in a similarly designed silver (Ag) capsule and capsule-free René 41 autoclave. Secondary ion mass spectrometry (SIMS) analysis revealed transition metal free (<1×1017 cm-3) GaN crystals. Anomalously low oxygen concentrations ((2-6)×1018 cm-3) were measured in a {0001} seeded crystal boule grown using a Mo capsule, despite higher source material oxygen concentrations ((1-5)×1019 cm-3) suggesting that molybdenum (or molybdenum nitrides) may act to getter oxygen under certain conditions. Total system pressure profiles from growth runs in a Mo capsule system were comparable to those without a capsule, with pressures peaking within 2 days and slowly decaying due to hydrogen diffusional losses. Measured Mo capsule GaN growth rates were comparable to un-optimized growth rates in capsule-free systems and appreciably slower than in Ag-capsule systems. Crystal quality replicated that of the GaN seed crystals for all capsule conditions, with high quality growth occurring on the (0001) Ga-face. Optical absorption and impurity concentration characterization suggests reduced concentrations of hydrogenated gallium vacancies (VGa-Hx).

  15. Syntheses Characterization of Chloro-cyclopentadienyltricarbonyl-molybdenum with β-Cyclodextrin Supramolecular

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Organotransition metal complex have been extensively used as homogeneous catalysts in organic reactions and much effort has been paid to improve their activity and selectively. Cyclodextrins have been studied as a model of enzyme for selective catalysis. However, so far there are only a few reports on the inclusion compounds of organometallic complexes with cyclodextrins. Breslow et al.repored high acylation rates for β-CD using ferrocene derivatives and assumed β-CD substrate complexes as intermediate [1]..larad et al reported the preparation and propertics of cyclodextrin-ferrocen inclusion compounds as the first example of cyclodextrin inclusion compounds of organotransition metal complexes[2]. Song Le-Xin et al reported the supramolecular inclusion compound of β-cyclodextrin with cyclopentadieny-tricarbonylmanganese [3] .To our knowledge, there are no reports of inclusion compounds of β-CD with molybdenum organometallic complexes. In the present work we described the preparation and properties of the supramolecular of CpMo(CO)3Cl with β-CD in details.

  16. A New Convenient Method for the Resolution of 1,1′—Binaphthalene—2,2′—diol Via a Phosphite Using(—)—Menthol as Resolving Agnet

    Institute of Scientific and Technical Information of China (English)

    JueXiaoCAI; ChihuangYEUNG; 等

    2002-01-01

    (-)-Menthol reacts with phosphorus trichloride to afford menthyl phosphorodichloridite 2,which further reacts with racemic 1,1′-binaphthalene-2,2′- diol to give phosphite (±)-3 in the presence of triethylamine.(±)-3 can be easily separated by fractional crystallization to from the crystal (+)-(S)-3 and the mother liquor(-)-(R)-3. Then both the crystal and the mother liquor are treated with AcOH-H2O to obtain enantiomeric pure(-)-(S)-1 and (+)-(R)-1 respectively, with enantiomeric excess up to 99.7%.

  17. Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

    2015-03-02

    A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

  18. Ab initio study of the operating mechanisms of tris(trimethylsilyl) phosphite as a multifunctional additive for Li-ion batteries

    Science.gov (United States)

    Kim, Dong Young; Park, Hosang; Choi, Woon Ih; Roy, Basab; Seo, Jinah; Park, Insun; Kim, Jin Hae; Park, Jong Hwan; Kang, Yoon-Sok; Koh, Meiten

    2017-07-01

    Tris(trimethylsilyl) phosphite (P(OSi(CH3)3)3) is a multifunctional electrolyte additive for scavenging HF and forming a cathode electrolyte interphase (CEI). Systematic analysis of the HF reaction pathways and redox potentials of P(OSi(CH3)3)3, OP(OSi(CH3)3)3, P(OSiF3)3, and OP(OSiF3)3, and their reaction products, using ab initio calculations allowed us to elucidate the operating mechanism of P(OSi(CH3)3)3 and verify the rules that determine its HF reaction pathways and electrochemical stability. While Osbnd Si cleavage is the predominant HF scavenging pathway for P(OSi(CH3)3)3, Osbnd P cleavage is stabilized by replacing CH3 with an electron-withdrawing group. Thus, P(OSiF3)3 scavenges HF mainly through Osbnd P cleavage to produce PF3, which has high oxidation stability. However, the Osbnd Si cleavage pathway produces P(OSi(CH3)3)2OH, P(OSi(CH3)3) (OH)2, and P(OH)3 sequentially, along with Si(CH3)3F. These PO3 systems, which are oxidized earlier than carbonate solutions and form tightly bonded units following oxidation, act as seed units for compact CEI growth. Moreover, the HF scavenging ability of PO3 systems is maintained during oxidation until all Osbnd Si bonds are broken. As a strategy for developing additives with enhanced functionality, modifying P(OSi(CH3)3)3 by replacing CH3 with an electron-donating group to exclusively utilize the Osbnd Si cleavage pathway for HF scavenging is recommended.

  19. LC-MS/MS analytical procedure to quantify tris(nonylphenyl)phosphite, as a source of the endocrine disruptors 4-nonylphenols, in food packaging materials.

    Science.gov (United States)

    Mottier, Pascal; Frank, Nancy; Dubois, Mathieu; Tarres, Adrienne; Bessaire, Thomas; Romero, Roman; Delatour, Thierry

    2014-01-01

    Tris(nonylphenyl)phosphite, an antioxidant used in polyethylene resins for food applications, is problematic since it is a source of the endocrine-disrupting chemicals 4-nonylphenols (4NP) upon migration into packaged foods. As a response to concerns surrounding the presence of 4NP-based compounds in packaging materials, some resin producers and additive suppliers have decided to eliminate TNPP from formulations. This paper describes an analytical procedure to verify the "TNPP-free" statement in multilayer laminates used for bag-in-box packaging. The method involves extraction of TNPP from laminates with organic solvents followed by detection/quantification by LC-MS/MS using the atmospheric pressure chemical ionisation (APCI) mode. A further acidic treatment of the latter extract allows the release of 4NP from potentially extracted TNPP. 4NP is then analysed by LC-MS/MS using electrospray ionisation (ESI) mode. This two-step analytical procedure ensures not only TNPP quantification in laminates, but also allows the flagging of other possible sources of 4NP in such packaging materials, typically as non-intentionally added substances (NIAS). The limits of quantification were 0.50 and 0.48 µg dm⁻² for TNPP and 4NP in laminates, respectively, with recoveries ranging between 87% and 114%. Usage of such analytical methodologies in quality control operations has pointed to a lack of traceability at the packaging supplier level and cross-contamination of extrusion equipment at the converter level, when TNPP-containing laminates are processed on the same machine beforehand.

  20. Mechanistic Insight in the Function of Phosphite Additives for Protection of LiNi0.5Co0.2Mn0.3O2 Cathode in High Voltage Li-Ion Cells.

    Science.gov (United States)

    He, Meinan; Su, Chi-Cheung; Peebles, Cameron; Feng, Zhenxing; Connell, Justin G; Liao, Chen; Wang, Yan; Shkrob, Ilya A; Zhang, Zhengcheng

    2016-05-11

    Triethlylphosphite (TEP) and tris(2,2,2-trifluoroethyl) phosphite (TTFP) have been evaluated as electrolyte additives for high-voltage Li-ion battery cells using a Ni-rich layered cathode material LiNi0.5Co0.2Mn0.3O2 (NCM523) and the conventional carbonate electrolyte. The repeated charge/discharge cycling for cells containing 1 wt % of these additives was performed using an NCM523/graphite full cell operated at the voltage window from 3.0-4.6 V. During the initial charge process, these additives decompose on the cathode surface at a lower oxidation potential than the baseline electrolyte. Impedance spectroscopy and post-test analyses indicate the formation of protective coatings by both additives on the cathode surface that prevent oxidative breakdown of the electrolyte. However, only TTFP containing cells demonstrate the improved capacity retention and Coulombic efficiency. For TEP, the protective coating is also formed, but low Li(+) ion mobility through the interphase layer results in inferior performance. These observations are rationalized through the inhibition of electrocatalytic centers present on the cathode surface and the formation of organophosphate deposits isolating the cathode surface from the electrolyte. The difference between the two phosphites clearly originates in the different properties of the resulting phosphate coatings, which may be in Li(+) ion conductivity through such materials.

  1. Extraction of transplutionium and rare-earth elements, molybdenum and iron with zirconium salt of dibutyl phosphoric acid

    Science.gov (United States)

    Zilberman, B. Ya.; Fedorov, Yu. S.; Shmidt, O. V.; Goletsky, N. D.; Sukhareva, S. Yu.; Puzikov, E. A.; Suglobov, D. N.; Mashirov, L. G.; Choppin, G. R.

    2003-01-01

    Zirconium salt of dibutyl phosphoric acid (ZS-HDBP) dissolved in dilute tributyl phosphate (TBP) is proposed as a solvent for separation of transplutonium and rare-earth elements (TPE, RE), including yttrium, from high-level waste in the presence of molybdenum and iron. The optimum HDBP:Zr ratio is 9 for RE and TPE extraction and is 12.5 for Mo. IR spectra indicate formation of Zr(DBP)4(HDBP)4 complex as a base of solvation. HNO3 depresses RE and TPE extraction, while Mo extraction is characterised by a minimum at 2.5 mol/L HNO3. Presence of TBP in the solvent, independently of the used diluent, leads to reduction of the distribution coefficients, but ZS-HDBP extraction capacity for the above elements is increased, as well as solubility of their solvates. Two types of complexes M(DBP)3 and MNO3(DBP)2 are formed at RE and TPE extraction by ZS-HDBP in dilute TBP. Molybdenum extraction is based both on cation exchange and on Mo solvation with HDBP as a neutral ligand. Iron extraction is formally similar to that of Mo, being influenced by the latter if both metals are present in the solution.

  2. Preconcentration by Using Microcrystalline Phenolphthalein for Determining Trace Molybdenum(Ⅵ) in Water by GFAAS

    Institute of Scientific and Technical Information of China (English)

    LI Quan-min; OUYANG Rui-zhuo; ZHU Gui-fen; LIU Guo-guang

    2005-01-01

    @@ Introduction Molybdenum(Ⅵ) is a biologically essential trace element and its role in an extremely wide variety of systems has been reported. Most common methods often fail to determine trace Mo(Ⅵ) in the analysis of molybdenum-containing samples, due to limitations such as inadequate detection limits and matrix interference, which make the direct determinations impossible.

  3. Measurement of Actinides in Molybdenum-99 Solution Analytical Procedure

    Energy Technology Data Exchange (ETDEWEB)

    Soderquist, Chuck Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weaver, Jamie L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-11-01

    This document is a companion report to a previous report, PNNL 24519, Measurement of Actinides in Molybdenum-99 Solution, A Brief Review of the Literature, August 2015. In this companion report, we report a fast, accurate, newly developed analytical method for measurement of trace alpha-emitting actinide elements in commercial high-activity molybdenum-99 solution. Molybdenum-99 is widely used to produce 99mTc for medical imaging. Because it is used as a radiopharmaceutical, its purity must be proven to be extremely high, particularly for the alpha emitting actinides. The sample of 99Mo solution is measured into a vessel (such as a polyethylene centrifuge tube) and acidified with dilute nitric acid. A gadolinium carrier is added (50 µg). Tracers and spikes are added as necessary. Then the solution is made strongly basic with ammonium hydroxide, which causes the gadolinium carrier to precipitate as hydrous Gd(OH)3. The precipitate of Gd(OH)3 carries all of the actinide elements. The suspension of gadolinium hydroxide is then passed through a membrane filter to make a counting mount suitable for direct alpha spectrometry. The high-activity 99Mo and 99mTc pass through the membrane filter and are separated from the alpha emitters. The gadolinium hydroxide, carrying any trace actinide elements that might be present in the sample, forms a thin, uniform cake on the surface of the membrane filter. The filter cake is first washed with dilute ammonium hydroxide to push the last traces of molybdate through, then with water. The filter is then mounted on a stainless steel counting disk. Finally, the alpha emitting actinide elements are measured by alpha spectrometry.

  4. Pyranopterin Coordination Controls Molybdenum Electrochemistry in Escherichia coli Nitrate Reductase*

    Science.gov (United States)

    Wu, Sheng-Yi; Rothery, Richard A.; Weiner, Joel H.

    2015-01-01

    We test the hypothesis that pyranopterin (PPT) coordination plays a critical role in defining molybdenum active site redox chemistry and reactivity in the mononuclear molybdoenzymes. The molybdenum atom of Escherichia coli nitrate reductase A (NarGHI) is coordinated by two PPT-dithiolene chelates that are defined as proximal and distal based on their proximity to a [4Fe-4S] cluster known as FS0. We examined variants of two sets of residues involved in PPT coordination: (i) those interacting directly or indirectly with the pyran oxygen of the bicyclic distal PPT (NarG-Ser719, NarG-His1163, and NarG-His1184); and (ii) those involved in bridging the two PPTs and stabilizing the oxidation state of the proximal PPT (NarG-His1092 and NarG-His1098). A S719A variant has essentially no effect on the overall Mo(VI/IV) reduction potential, whereas the H1163A and H1184A variants elicit large effects (ΔEm values of −88 and −36 mV, respectively). Ala variants of His1092 and His1098 also elicit large ΔEm values of −143 and −101 mV, respectively. An Arg variant of His1092 elicits a small ΔEm of +18 mV on the Mo(VI/IV) reduction potential. There is a linear correlation between the molybdenum Em value and both enzyme activity and the ability to support anaerobic respiratory growth on nitrate. These data support a non-innocent role for the PPT moieties in controlling active site metal redox chemistry and catalysis. PMID:26297003

  5. Molybdenum and copper levels in white-tailed deer near uranium mines in Texas

    Science.gov (United States)

    King, K.A.; LeLeux, J.; Mulhern, B.M.

    1984-01-01

    Molybdenum toxicity, molybdenosis, in ruminant animals has been identified in at least 15 states and in Canada, England, Australia, and New Zealand. In most western states, molybdenosis has been associated with strip-mine spoil deposits. Molybdenum toxicity has been diagnosed in cattle pastured near uranium strip-mine spoils in several Texas counties. Recent reports from hunters and the authors' observations indicated that white-tailed deer (Odocoileus virginianus ) that fed near uranium-mine spoil deposits may also have been exposed to high levels of molybdenum. The objectives of this study were to determine if white-tailed deer from a South Texas uranium mining district were accumulating harmful levels of molybdenum and to compare molybdenum and copper levels with antler development in deer from the mined area vs. an unmined control area.

  6. Dry sliding friction and wear characteristics of Fe-C-Cu alloy containing molybdenum di sulphide

    Energy Technology Data Exchange (ETDEWEB)

    Dhanasekaran, S. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Gnanamoorthy, R. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India)]. E-mail: gmoorthy@iitm.ac.in

    2007-07-01

    Sintered steels find increasing application as bearings and gears due to economical and technical reasons. Materials used for making these machine elements need to have high strength, good wear resistance and low coefficient of friction. An attempt is made to develop molybdenum di sulphide added iron-copper-carbon sintered steels using simple single stage compaction and sintering elemental powders. Friction and wear characteristics of the developed materials were evaluated using cylindrical specimens in a pin-on-disc sliding apparatus. Addition of molybdenum di sulphide increases the compressibility and increases the part density. Strength and hardness of the molybdenum di sulphide added compositions are better than the base composition. Addition of the 3% molybdenum di sulphide is found to be beneficial in improving friction and wear characteristics. Higher amount of brittle phases in the 5% molybdenum di sulphide added sample contributes to the reduction in the wear resistance.

  7. Investigation on the Performance of Supported Molybdenum Carbide for the Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Quanli Zhu; Jian Yang; Jiaxin Wang; Shengfu Ji; Hanqing Wang

    2003-01-01

    The performance of supported and unsupported molybdenum carbide for the partial oxida-tion of methane (POM) to syngas was investigated. An evaluation of the catalysts indicates that bulkmolybdenum carbide has a higher methane conversion during the initial stage but a lower selectivity toCO and H2/CO ratio in the products. The rapid deactivation of the catalyst is also a significant problem.However, the supported molybdenum carbide catalyst shows a much higher methane conversion, increasedselectivity and significantly improved catalytic stability. The characterization by XRD and BET specificarea measurements depict an improved dispersion of molybdenum carbide when using alumina as a carrier.The bulk or the supported molybdenum carbide exists in the β-Mo2C phase, while it is transformed intomolybdenum dioxide postcatalysis which is an important cause of molybdenum carbide deactivation.

  8. Leaching of molybdenum and arsenic from uranium ore and mill tailings

    Science.gov (United States)

    Landa, E.R.

    1984-01-01

    A sequential, selective extraction procedure was used to assess the effects of sulfuric acid milling on the geochemical associations of molybdenum and arsenic in a uranium ore blend, and the tailings derived therefrom. The milling process removed about 21% of the molybdenum and 53% of the arsenic initially present in the ore. While about one-half of the molybdenum in the ore was water soluble, only about 14% existed in this form in the tailings. The major portion of the extractable molybdenum in the tailings appears to be associated with hydrous oxides of iron, and with alkaline earth sulfate precipitates. In contrast with the pattern seen for molybdenum, the partitioning of arsenic into the various extractable fractions differs little between the ore and the tailings. ?? 1984.

  9. Disposition of plutonium-239 via production of fission molybdenum-99.

    Science.gov (United States)

    Mushtaq, A

    2011-04-01

    A heritage of physical consequences of the U.S.-Soviet arms race has accumulated, the weapons-grade plutonium (WPu), which will become excess as a result of the dismantlement of the nuclear weapons under the arms reduction agreements. Disposition of Pu has been proposed by mixing WPu with high-level radioactive waste with subsequent vitrification into large, highly radioactive glass logs or fabrication into mixed oxide fuel with subsequent irradiation in existing light water reactors. A potential option may be the production of medical isotope molybdenum-99 by using Pu-239 targets.

  10. Wettability and photochromic behaviour of Molybdenum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Allogho, Guy-Germain, E-mail: guy-germain.allogho@umoncton.ca; Ashrit, P.V., E-mail: pandurang.ashrit@umoncton.ca

    2012-01-01

    The temporal wettability (hydrophobic-hydrophilic) behaviour of thermally evaporated Molybdenum oxide thin films is examined via water droplet contact angle and water droplet lifetime measurements. Super-hydrophilic state is quickly achieved in these films and the rapidity of this conversion depends strongly on the film preparation conditions. It is found that film microstructure, humidity content and UV irradiation have a profound influence on the wettability behaviour of these films. The ensuing photochromic effect under UV irradiation is also followed through the optical changes occurring in the film. Films deposited at higher chamber pressure have a generally smaller initial contact angle and lifetime.

  11. Transcriptional regulation of nitrogen fixation by molybdenum in Azotobacter vinelandii.

    OpenAIRE

    Jacobson, M.R.; Premakumar, R; Bishop, P E

    1986-01-01

    Multiple genomic regions homologous to nifH were found in the diazotroph Azotobacter vinelandii. The nifHDK gene cluster, located on a 12.8-kilobase (kb) XhoI fragment and two additional XhoI fragments (7.4 and 8.4 kb) hybridized to a nifH-specific DNA template but the 7.4- and 8.4-kb fragments did not hybridize to nifD- or nifK-specific DNA probes. In vivo transcription of the nifHDK gene cluster was ammonia-repressible and required the presence of at least 50 nM molybdenum in the derepressi...

  12. Growth of molybdenum disulphide using iodine as transport material

    Indian Academy of Sciences (India)

    Rajiv Vaidya; Madhavi Dave; S S Patel; S G Patel; A R Jani

    2004-09-01

    In the present paper an attempt has been made to describe the chemical vapor transport (CVT) technique used for the growth of molybdenum disulphide (MoS2) single crystals. Iodine (I2) is used as transporting material for this purpose. The energy dispersive analysis by X-ray (EDAX) confirmed the stoichiometry of the as-grown crystals. The lattice parameters of these crystals were determined from the X-ray diffraction analysis. The grown crystals were examined under the optical zoom microscope for their surface microstructure study.

  13. Choice of anesthesia in molybdenum cofactor deficiency: A case report

    Directory of Open Access Journals (Sweden)

    Metin Alkan

    2014-01-01

    Full Text Available Molybdenum cofactor (MC deficiency is defined as a progressive neurodegenerative and neurometabolic disease, characterized by convulsions, severe mental and motor retardation resistant to the treatment. Patients with MC deficiency usually need at least sedation for even minor interventions such as dental examination or treatment. Sedation or general anesthesia for these patients may be complicated due to accompanying disorders. However, we were unable to find any reports on anesthetic management of patients with MC deficiency in the literature. In this article, we intend to share our experience of a patient with MC deficiency, who had undergone dental treatment under deep sedation.

  14. Geology of the Starr molybdenum mine, Okanogan County, Washington

    Science.gov (United States)

    Creasey, S.C.

    1954-01-01

    The Starr molybdenum mine, Okanogan County, Wash., is about 5 airline miles west of Tonasket in the north-central part of the State. The mineralized zone has been explored to a depth of 250 feet by means of three adit levels, one sublevel, and a raise which connects two of the adits and the sublevel. In all, there are about 2,700 feet of underground workings. The mine has neither machinery nor a developed water supply adequate for any work other than a small exploratory program.

  15. Influence of added molybdenum on the activity of DESONOX catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Marcewicz-Kuba, A.; Nazimek, D.

    2002-07-01

    The catalytic removal of SO{sub 2} from combustion gases has been studied on the grain plane of a hard coal, being competitive with classical desulphurization processes. The method proposed for the removal of SO{sub 2} from combustion gases described in this paper is quite different from wet classical desulphurization methods. Studies of the influence of molybdenum concentration on the catalytic activity of a number of DESONOX catalysts are reported. The influence of the total surface area and other physicochemical properties of the catalyst on its behaviour have been studied.

  16. Procedure for Uranium-Molybdenum Density Measurements and Porosity Determination

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-08-13

    The purpose of this document is to provide guidelines for preparing uranium-molybdenum (U-Mo) specimens, performing density measurements, and computing sample porosity. Typical specimens (solids) will be sheared to small rectangular foils, disks, or pieces of metal. A mass balance, solid density determination kit, and a liquid of known density will be used to determine the density of U-Mo specimens using the Archimedes principle. A standard test weight of known density would be used to verify proper operation of the system. By measuring the density of a U-Mo sample, it is possible to determine its porosity.

  17. Standard Specification for Pressure Consolidated Powder Metallurgy Iron-Nickel-Chromium-Molybdenum (UNS N08367), Nickel-Chromium-Molybdenum-Columbium (Nb) (UNS N06625), Nickel-Chromium-Iron Alloys (UNS N06600 and N06690), and Nickel-Chromium-Iron-Columbium-Molybdenum (UNS N07718) Alloy Pipe Flanges, Fittings, Valves, and Parts

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Pressure Consolidated Powder Metallurgy Iron-Nickel-Chromium-Molybdenum (UNS N08367), Nickel-Chromium-Molybdenum-Columbium (Nb) (UNS N06625), Nickel-Chromium-Iron Alloys (UNS N06600 and N06690), and Nickel-Chromium-Iron-Columbium-Molybdenum (UNS N07718) Alloy Pipe Flanges, Fittings, Valves, and Parts

  18. 含钼铜精矿氧化焙烧-浸出分离钼研究%Study on sepatation of molybdenum ftom molybdenum-containing coppet concenttate by oxidizing toasting-leaching

    Institute of Scientific and Technical Information of China (English)

    肖军辉; 施哲; 陈金花

    2016-01-01

    Absttact:An oxidizing roasting-leaching flowsheet was proposed to further separate molybdenum because of complex minerals composition and tightness paragenetic relationship of molybdenum and copper in the molybdenum-containing copper concentrate in western Panzhihua of Sichuan province.Samples were put into the roasting furnace to conduct oxidizing roasting,and sulphide ore was oxidized into CuO,MoO3 , Fe2 O3 ,etc.Then,NaOH and H2 O were added to react with MoO3 ,and Na2 MoO4 was produced,and leaching residue was taken as the copper concentrate.Study results indicate that copper and molybdenum occur in the form of oxide in the roasting ores.The sulfur content is 0.53%in the roasting ores,and sulfur volatilizes in the form of SO2 .The leaching ratio of molybdenum is 94.24%and the copper mass fraction in the copper concentrate(leaching residue)is 24.27% when the roasting temperature is 650 ℃,roasting time is 120 min,NaOH dosage is 30%,leaching temperature is 60℃,leaching time is 120 min,and leaching liquid-solid ratio is 2∶1 .The effect of molybdenum separation is obvious.%四川攀西地区的含钼铜精矿中,由于钼、铜矿物组成复杂,共生关系紧密,提出了氧化焙烧-浸出工艺进一步分离钼。将试样置入焙烧炉中进行氧化焙烧,使硫化物转化为CuO、MoO3、Fe2 O3等氧化物后;添加NaOH、H2 O 与 MoO3反应生成可溶性Na2 MoO4,浸出渣作为铜精矿产品。研究结果表明:铜、钼等以氧化物形式赋存于焙烧矿中,氧化焙烧矿中的硫含量较低为0.53%,硫以SO2气相形式挥发;在焙烧温度650℃、焙烧时间120 min、氢氧化钠用量为30%、浸出温度60℃、浸出时间120 min、浸出液固比2∶1的综合条件下,钼的浸出率为94.24%,铜精矿(浸出渣)中铜的质量分数为24.27%,钼分离效果明显。

  19. Oxygen isotope studies of phosphite oxidation: purification and analysis of reactants and products by high-temperature conversion elemental analyzer/isotope ratio mass spectrometry.

    Science.gov (United States)

    Chang, Sae Jung; Blake, Ruth E

    2015-11-15

    Increased attention has been recently focused on the origin and reactions of reduced-P oxyanions such as phosphite [PO3 (III)] in terrestrial and biological systems. We present new methods for studying O-isotopic reactions between PO3 (III) and other oxygen sources during oxidation of PO3 (III) to PO4 (V). Na2 (HPO3 )·5H2 O, used as a PO3 (III) source, contains structural water due to its hygroscopic nature; thus, we developed a method for determining the δ(18) O value of PO3 (III) after the removal of structural water. Next, we tested two techniques for purifying PO4 (V) from aqueous PO3 (III)/PO4 (V) mixtures: (1) precipitation of PO4 (V) as ammonium phosphomolybdate (APM); and (2) precipitation of PO4 (V) as magnesium ammonium phosphate (MAP). The O-isotope compositions, (18) O:(16) O (δ(18) O values), of Na2 (HPO3 ) and Ag3 PO4 were analyzed by TC/EA/IRMS. Structural water was removed from Na2 (HPO3 )·5H2 O after drying at 100 °C under vacuum and the δ(18) O value of PO3 (III) was obtained. The δ(18) O values of PO4 (V), which was extracted from (18) O-labeled PO3 (III)/PO4 (V) mixtures by APM and MAP precipitations, were not altered by the precipitation process. This result confirms that PO3 (III) is not converted into PO4 (V) by oxidation or hydrolysis under either strong acidic/oxidizing (APM) or alkaline (MAP) conditions for up to a 24-h period. We conclude that both APM and MAP precipitation are reliable and effective methods for the separation and purification of PO4 (V) from aqueous PO3 (III)/PO4 (V) mixtures. The methods described here will permit the study of the isotopic evolution of various pathways of geochemical as well as biological PO3 (III) oxidation. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Plant growth in amended molybdenum mine waste rock.

    Science.gov (United States)

    Burney, Owen T; Redente, Edward F; Lambert, Charles E

    2017-04-01

    This greenhouse study examined the use of organic and inorganic soil amendments in waste rock material from the former Questa Molybdenum Mine in northern New Mexico to promote beneficial soil properties. Waste rock material was amended with 11 soil amendment treatments that included municipal composted biosolids, Biosol®, inorganic fertilizer, and two controls (pure waste rock and sand). Elymus trachycaulus and Robinia neomexicana growth performance and plant chemistry were assessed across all treatments over a period of 99 and 141 days, respectively. Even though waste rock material had more than 200 times the molybdenum concentration of native soils, adverse effects were not observed for either species. The two main limiting factors in this study were soil nutritional status and soil water retention. The biosolid amendment was found to provide the greatest buffer against these limiting factors due to significant increases in both nutrition and soil water retention. As a result, both species responded with the highest levels of biomass production and the least amount of required water demands. Use of organic amendments such as biosolids, even though short lived in the soil, may provide plants the necessary growth stimulus to become more resilient to the harsh conditions found on many mine reclamation sites.

  1. Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide.

    Science.gov (United States)

    van der Zande, Arend M; Huang, Pinshane Y; Chenet, Daniel A; Berkelbach, Timothy C; You, YuMeng; Lee, Gwan-Hyoung; Heinz, Tony F; Reichman, David R; Muller, David A; Hone, James C

    2013-06-01

    Recent progress in large-area synthesis of monolayer molybdenum disulphide, a new two-dimensional direct-bandgap semiconductor, is paving the way for applications in atomically thin electronics. Little is known, however, about the microstructure of this material. Here we have refined chemical vapour deposition synthesis to grow highly crystalline islands of monolayer molybdenum disulphide up to 120 μm in size with optical and electrical properties comparable or superior to exfoliated samples. Using transmission electron microscopy, we correlate lattice orientation, edge morphology and crystallinity with island shape to demonstrate that triangular islands are single crystals. The crystals merge to form faceted tilt and mirror twin boundaries that are stitched together by lines of 8- and 4-membered rings. Density functional theory reveals localized mid-gap states arising from these 8-4 defects. We find that mirror twin boundaries cause strong photoluminescence quenching whereas tilt boundaries cause strong enhancement. Meanwhile, mirror twin boundaries slightly increase the measured in-plane electrical conductivity, whereas tilt boundaries slightly decrease the conductivity.

  2. Reprocessability of molybdenum and magnesia based inert matrix fuels

    Directory of Open Access Journals (Sweden)

    Ebert Elena L.

    2015-12-01

    Full Text Available This work focuses on the reprocessability of metallic 92Mo and ceramic MgO, which is under investigation for (Pu,MA-oxide (MA = minor actinide fuel within a metallic 92Mo matrix (CERMET and a ceramic MgO matrix (CERCER. Magnesium oxide and molybdenum reference samples have been fabricated by powder metallurgy. The dissolution of the matrices was studied as a function of HNO3 concentration (1-7 mol/L and temperature (25-90°C. The rate of dissolution of magnesium oxide and metallic molybdenum increased with temperature. While the MgO rate was independent of the acid concentration (1-7 mol/L, the rate of dissolution of Mo increased with acid concentration. However, the dissolution of Mo at high temperatures and nitric acid concentrations was accompanied by precipitation of MoO3. The extraction of uranium, americium, and europium in the presence of macro amounts of Mo and Mg was studied by three different extraction agents: tri-n-butylphosphate (TBP, N,Nʹ-dimethyl-N,Nʹ-dioctylhexylethoxymalonamide (DMDOHEMA, and N,N,N’,N’- -tetraoctyldiglycolamide (TODGA. With TBP no extraction of Mo and Mg occurred. Both matrix materials are partly extracted by DMDOHEMA. Magnesium is not extracted by TODGA (D < 0.1, but a weak extraction of Mo is observed at low Mo concentration.

  3. Synthesis and characterization of several molybdenum chloride cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Beers, W.W.

    1983-06-01

    Investigation into the direct synthesis of Mo/sub 4/Cl/sub 8/(P(C/sub 2/H/sub 5/)/sub 3/)/sub 4/ from Mo/sub 2/(OAc)/sub 4/ led to a synthetic procedure that produces yields greater than 80%. The single-crystal structure disclosed a planar rectangular cluster of molybdenum atoms. Metal-metal bond distances suggest that the long edges of the rectangular cluster should be considered to be single bonds and the short metal-metal bonds to be triple bonds. This view is reinforced by an extended Hueckel calculation. Attempts to add a metal atom to Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 4/ to form Mo/sub 5/Cl/sub 10/(PR/sub 3/)/sub 3/ led instead to a compound with the composition Mo/sub 8/Cl/sub 16/(PR/sub 3/)/sub 4/. Solution and reflectance uv-visible spectra and x-ray photoelectron spectra suggest that tetranuclear molybdenum units are present. The facile reaction between Mo/sub 8/Cl/sub 16/(PR/sub 3/)/sub 4/ and PR/sub 3/ imply that the linkage between tetrameric units is weak.

  4. 极谱法测定钼矿石中的总钼氧化钼硫化钼%Determination of Total Molybdenum, Molybdic Oxide and Molybdenum Sulfide in Molybdenum Ore by Polarography

    Institute of Scientific and Technical Information of China (English)

    薛静

    2012-01-01

    Molybdenite is the major mineral in molybdenum ore. The phase analysis of molybdenum ore is required to determine sulfide minerals and oxide minerals. The phase analyses of molybdenum ores such as molybdenite, molybdite, powellite and molybdate galena were taken by photometry and Inductively Coupled Plasma-Atomic Emission Spectrometry ( ICP-AES). In this paper, the molybdenum ore sample was dissolved with aqua regia-sulfuric acid. The total molybdenum was extracted by alkali solution and the majority of the other elements were separated by precipitation. Molybdic oxides were leached by sodium carbonate and ammonium hydroxide solution. Molybdenum sulfides were obtained to dissolve residue. The contents of total molybdenum, molybdic oxide and molybdenum sulfide were determined by rapid polarography in a sulfuric acid-potassium chlorate-diphenyl glycollic acid system. The linear range of the method was 0. 04 -0. 4 mg/L, and the detection limit was 0. 028 mg/L. Three molybdenum ore samples were carried on phase analysis and the results were consistent with those obtained by photometry. The sum contents of molybdic oxide and molybdenum sulfide conformed to the total molybdenum content. RSDs (n=8) were 1.69% -3.56% for total molybdenum, molybdic oxide and molybdenum sulfide. This method was fast and suitable for practical batch samples.%钼的物相分析要求测定硫化矿物相和氧化矿物相,常用比色法和电感耦合等离子体发射光谱法等对辉钼矿、钼华矿、钼钨钙矿、钼酸铅矿等钼矿石进行物相分析,但分离物相的品种较多,方法繁琐耗时.本文用王水-硫酸消解钼矿石样品,碱溶液复溶浸提得到钼总量,使其他大多数元素形成沉淀而分离,用碳酸钠-氢氧化铵混合溶液浸取钼的氧化矿物,将残渣进一步溶解得到硫化矿物含量,在硫酸-氯酸钾-二苯羟乙酸体系中用极谱法简单快速测定钼总量、氧化钼和硫化钼含量.方法的线性范围为0.04~0

  5. 钼冶金技术发展近况%THE RECENT DEVELOPMENT OF METALLURGICAL TECHNOLOGY FOR MOLYBDENUM

    Institute of Scientific and Technical Information of China (English)

    张文钲; 刘燕

    2013-01-01

    评介了钼冶金产品生产技术的最近进展,如钼精矿转化工业氧化钼、钼精矿氧压煮生产化学纯三氧化钼、用氧化剂和浸出剂同时处理钼精矿生产化学纯三氧化钼,从钼精矿直接制取钼铁,用双十三胺萃取钼酸盐,反萃工艺生产二钼酸铵和钼粉、钼造粒粉等.%The latest development of molybdenum metallurgical technology has been discussed,including turning molybdenum concentrate into industrial-grade molybdenum oxide,producing chemically-pure molybdenum trioxide from molybdenum concentrate by MAP,producing chemically-pure molybdenum trioxide by simultaneously processing molybdenum concentrate with oxidant and leaching agent,directly making ferro-molybdenum from molybdenum concentrate,extracting molybdate using ditridecylamine,producing ammonium dimolybdate,molybdenum powder and molybdenum granulated power through re-extraction technology.

  6. Highly dispersed molybdenum carbide as non-noble electrocatalyst for PEM fuel cells: Performance for CO electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Guil-Lopez, R.; Martinez-Huerta, M.V.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie 2, Cantoblanco, E-28049 Madrid (Spain); Guillen-Villafuerte, O.; Pastor, E. [Departamento de Quimica Fisica, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, E-38071 La Laguna, Tenerife (Spain)

    2010-08-15

    CO electrooxidation on nanocrystalline molybdenum carbide has been studied through CO stripping measurements using cyclic voltammetry. The active molybdenum carbide was obtained from the carbothermic reduction of really very small molybdenum oxide particles supported on Vulcan XC-72 carbon black (CB). In order to obtain highly dispersed molybdenum carbide particles, low molybdenum loading and control of the carbothermic reduction conditions of CB-supported molybdenum oxide were employed to avoid Mo sintering during the carburization process. This work provides experimental evidence on the CO electrooxidation capability of the Mo carbide phase, which to the best of our knowledge is reported for the first time. The small particle size of carbide electrocatalyst exhibited better performance for CO electrooxidation than the commercial bulk molybdenum carbide sample. (author)

  7. Environmental Benign Process for Production of Molybdenum Metal from Sulphide Based Minerals

    Science.gov (United States)

    Rajput, Priyanka; Janakiram, Vangada; Jayasankar, Kalidoss; Angadi, Shivakumar; Bhoi, Bhagyadhar; Mukherjee, Partha Sarathi

    2017-02-01

    Molybdenum is a strategic and high temperature refractory metal which is not found in nature in free state, it is predominantly found in earth's crust in the form of MoO3/MoS2. The main disadvantage of the industrial treatment of Mo concentrate is that the process contains many stages and requires very high temperature. Almost in every step many gaseous, liquid, solid chemical substances are formed which require further treatment. To overcome the above drawback, a new alternative one step novel process is developed for the treatment of sulphide and trioxide molybdenum concentrates. This paper presents the results of the investigations on molybdenite dissociation (MoS2) using microwave assisted plasma unit as well as transferred arc thermal plasma torch. It is a single step process for the preparation of pure molybdenum metal from MoS2 by hydrogen reduction in thermal plasma. Process variable such as H2 gas, Ar gas, input current, voltage and time have been examined to prepare molybdenum metal. Molybdenum recovery of the order of 95% was achieved. The XRD results confirm the phases of molybdenum metal and the chemical analysis of the end product indicate the formation of metallic molybdenum (Mo 98%).

  8. Variation in molybdenum content across broadly distributed populations of Arabidopsis thaliana is controlled by a mitochondrial molybdenum transporter (MOT1.

    Directory of Open Access Journals (Sweden)

    Ivan Baxter

    2008-02-01

    Full Text Available Molybdenum (Mo is an essential micronutrient for plants, serving as a cofactor for enzymes involved in nitrate assimilation, sulfite detoxification, abscisic acid biosynthesis, and purine degradation. Here we show that natural variation in shoot Mo content across 92 Arabidopsis thaliana accessions is controlled by variation in a mitochondrially localized transporter (Molybdenum Transporter 1 - MOT1 that belongs to the sulfate transporter superfamily. A deletion in the MOT1 promoter is strongly associated with low shoot Mo, occurring in seven of the accessions with the lowest shoot content of Mo. Consistent with the low Mo phenotype, MOT1 expression in low Mo accessions is reduced. Reciprocal grafting experiments demonstrate that the roots of Ler-0 are responsible for the low Mo accumulation in shoot, and GUS localization demonstrates that MOT1 is expressed strongly in the roots. MOT1 contains an N-terminal mitochondrial targeting sequence and expression of MOT1 tagged with GFP in protoplasts and transgenic plants, establishing the mitochondrial localization of this protein. Furthermore, expression of MOT1 specifically enhances Mo accumulation in yeast by 5-fold, consistent with MOT1 functioning as a molybdate transporter. This work provides the first molecular insight into the processes that regulate Mo accumulation in plants and shows that novel loci can be detected by association mapping.

  9. Role of electron concentration in softening and hardening of ternary molybdenum alloys

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R.

    1975-01-01

    Effects of various combinations of hafnium, tantalum, rhenium, osmium, iridium, and platinum in ternary molybdenum alloys on alloy softening and hardening were determined. Hardness tests were conducted at four test temperatures over the temperature range 77 to 411 K. Results showed that hardness data for ternary molybdenum alloys could be correlated with anticipated results from binary data based upon expressions involving the number of s and d electrons contributed by the solute elements. The correlation indicated that electron concentration plays a dominant role in controlling the hardness of ternary molybdenum alloys.

  10. Comparison of effects on crustaceans: carbon nanoparticles and molybdenum compounds nanowires

    Science.gov (United States)

    Baumerte, A.; Sakale, G.; Zavickis, J.; Putna, I.; Balode, M.; Mrzel, A.; Knite, M.

    2013-04-01

    Carbon nanomaterials (CNM) and molybdenum compound nanostructures are materials with various applications yet little is known regarding the toxicity of these nanoparticles in pristine form in aquatic environment. Daphnia magna standard acute toxicity test (EN ISO 6341:1996; freshwater) and Artemia salina standard acute toxicity test (ArtoxKit standard method; 15 ppt saltwater) were applied to assess the toxicity of non-modified CNM and molybdenum compound nanowires in water. It has been observed that CNM are more toxic in freshwater suspensions and somewhat more toxic than the tested molybdenum compound nanowires.

  11. Synthesis of molybdenum oxide microsheets via close-spaced vapor transport

    Energy Technology Data Exchange (ETDEWEB)

    Goiz, O., E-mail: ogoiza@gmail.com [Department of Electrical Engineering, CINVESTAV-IPN, 07360 Mexico, D.F. (Mexico); Chavez, F. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72050 Puebla, Pue. (Mexico); Felipe, C. [Department of Biosciences and Engineering, CIIEMAD-IPN, 07340 Mexico, D.F. (Mexico); Morales, N. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72050 Puebla, Pue. (Mexico); Pena-Sierra, R. [Department of Electrical Engineering, CINVESTAV-IPN, 07360 Mexico, D.F. (Mexico)

    2010-10-25

    Growth of molybdenum oxide microsheets on silicon (1 0 0) substrates using the close-spaced vapor transport (CSVT) technique is proposed. Molybdenum oxide powder is employed as source, the synthesis is carried out at atmospheric pressure with a nitrogen ambient by employing short times (a few minutes), water as reactant and moderate temperatures. The growth process is efficient, fast, and without the use of catalysts. Changes in morphology and structure of products when temperature varies are reported. The produced molybdenum oxide microsheets are analyzed with SEM, XRD and micro-Raman techniques.

  12. Differential pulse polarographic determination of molybdenum after separation by 8-hydroxyquinoline extraction into dichloromethane.

    Science.gov (United States)

    Nagaosa, Y; Kobayashi, K

    1984-08-01

    A polarographic investigation of several metal 8-hydroxyquinolinates in dichloromethane medium following solvent extraction has been made. From the data obtained, a selective, specific and sensitive method for the determination of molybdenum at ng ml levels has been developed involving direct differential pulse polarographic measurement on the dichloromethane extract. In this work, EDTA is used as an effective masking agent to separate molybdenum from other metals. The proposed method has been applied to the determination of molybdenum in a variety of steels and NBS-SRM 1577 bovine liver with good accuracy and precision.

  13. Acidic ammonothermal growth of gallium nitride in a liner-free molybdenum alloy autoclave

    Science.gov (United States)

    Malkowski, Thomas F.; Pimputkar, Siddha; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji

    2016-12-01

    This paper discusses promising materials for use as internal, non-load bearing components as well as molybdenum-based alloys for autoclave structural components for an ammonothermal autoclave. An autoclave was constructed from the commercial titanium-zirconium-molybdenum (TZM) alloy and was found to be chemically inert and mechanically stable under acidic ammonothermal conditions. Preliminary seeded growth of GaN was demonstrated with negligible incorporation of transition metals (including molybdenum) into the grown material (560 °C). The possibility of a 'universal', inexpensive, liner-free ammonothermal autoclave capable of exposure to basic and acidic chemistry is demonstrated.

  14. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    Science.gov (United States)

    Hilsenbeck, Shane J.; McCarley, Robert E.; Schrader, Glenn L.; Xie, Xiaobing

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  15. Molybdenum Disilicide Oxidation Kinetics in High Temperature Steam

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Elizabeth Sooby [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Stephen Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andrew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-07

    The Fuel Cycle Research and Development program’s Advanced Fuels Campaign is currently supporting a range of experimental efforts aimed at the development and qualification of ‘accident tolerant’ nuclear fuel forms. One route to enhance the accident tolerance of nuclear fuel is to replace the zirconium alloy cladding, which is prone to rapid oxidation in steam at elevated temperatures, with a more oxidation resistant cladding. Several cladding replacement solutions have been envisaged. The cladding can be completely replaced with a more oxidation resistant alloy, a layered approach can be used to optimize the strength, creep resistance, and oxidation tolerance of various materials, or the existing zirconium alloy cladding can be coated with a more oxidation resistant material. Molybdenum is one candidate cladding material favored due to its high temperature creep resistance. However, it performs poorly under autoclave testing and suffers degradation under high temperature steam oxidation exposure. Development of composite cladding architectures consisting of a molybdenum core shielded by a molybdenum disilicide (MoSi2) coating is hypothesized to improve the performance of a Mo-based cladding system. MoSi2 was identified based on its high temperature oxidation resistance in O2 atmospheres (e.g. air and “wet air”). However, its behavior in H2O is less known. This report presents thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and x-ray diffraction (XRD) results for MoSi2 exposed to 670-1498 K water vapor. Synthetic air (80-20%, Ar-O2) exposures were also performed and those results are presented here for a comparative analysis. It was determined that MoSi2 displays drastically different oxidation behavior in water vapor than in dry air. In the 670-1498 K temperature range, four distinct behaviors are observed. Parabolic oxidation is exhibited in only 670-773 K

  16. Molybdenum Disilicide Oxidation Kinetics in High Temperature Steam

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Elizabeth Sooby [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Stephen Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andrew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-07

    The Fuel Cycle Research and Development program’s Advanced Fuels Campaign is currently supporting a range of experimental efforts aimed at the development and qualification of ‘accident tolerant’ nuclear fuel forms. One route to enhance the accident tolerance of nuclear fuel is to replace the zirconium alloy cladding, which is prone to rapid oxidation in steam at elevated temperatures, with a more oxidation-resistant cladding. Several cladding replacement solutions have been envisaged. The cladding can be completely replaced with a more oxidation resistant alloy, a layered approach can be used to optimize the strength, creep resistance, and oxidation tolerance of various materials, or the existing zirconium alloy cladding can be coated with a more oxidation-resistant material. Molybdenum is one candidate cladding material favored due to its high temperature creep resistance. However, it performs poorly under autoclave testing and suffers degradation under high temperature steam oxidation exposure. Development of composite cladding architectures consisting of a molybdenum core shielded by a molybdenum disilicide (MoSi2) coating is hypothesized to improve the performance of a Mo-based cladding system. MoSi2 was identified based on its high temperature oxidation resistance in O2 atmospheres (e.g. air and “wet air”). However, its behavior in H2O is less known. This report presents thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and x-ray diffraction (XRD) results for MoSi2 exposed to 670-1498 K water vapor. Synthetic air (80-20%, Ar-O2) exposures were also performed, and those results are presented here for a comparative analysis. It was determined that MoSi2 displays drastically different oxidation behavior in water vapor than in dry air. In the 670-1498 K temperature range, four distinct behaviors are observed. Parabolic oxidation is exhibited in only 670

  17. Powder Metallurgy Fabrication of Molybdenum Accelerator Target Disks

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Richard Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kiggans Jr., James O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nunn, Stephen D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parten, Randy J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-07-01

    Powder metallurgy approaches for the fabrication of accelerator target disks are being examined to support the development of Mo-99 production by NorthStar Medical Technologies, LLC. An advantage of powder metallurgy is that very little material is wasted and, at present, dense, quality parts are routinely produced from molybdenum powder. The proposed targets, however, are thin wafers, 29 mm in diameter with a thickness of 0.5 mm, with very stringent dimensional tolerances. Although tooling can be machined to very high tolerance levels, the operations of powder feed, pressing and sintering involve complicated mechanisms, each of which affects green density and shrinkage, and therefore the dimensions and shape of the final product. Combinations of powder morphology, lubricants and pressing technique have been explored to produce target disks with minimal variations in thickness and little or no distortion. In addition, sintering conditions that produce densities for optimum target dissolvability are being determined.

  18. Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation

    Science.gov (United States)

    Zhu, Gaohua; Liu, Jun; Zheng, Qiye; Zhang, Ruigang; Li, Dongyao; Banerjee, Debasish; Cahill, David G.

    2016-10-01

    Thermal conductivity of two-dimensional (2D) materials is of interest for energy storage, nanoelectronics and optoelectronics. Here, we report that the thermal conductivity of molybdenum disulfide can be modified by electrochemical intercalation. We observe distinct behaviour for thin films with vertically aligned basal planes and natural bulk crystals with basal planes aligned parallel to the surface. The thermal conductivity is measured as a function of the degree of lithiation, using time-domain thermoreflectance. The change of thermal conductivity correlates with the lithiation-induced structural and compositional disorder. We further show that the ratio of the in-plane to through-plane thermal conductivity of bulk crystal is enhanced by the disorder. These results suggest that stacking disorder and mixture of phases is an effective mechanism to modify the anisotropic thermal conductivity of 2D materials.

  19. Structural and electrical properties of DC sputtered molybdenum films

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo, G.; Grizalez, M.; Hernandez, L.C. [Laboratorio de Celdas Solares, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)

    1998-02-27

    A method is described for the fabrication of low-resistivity molybdenum films on soda-lime glass substrates. Films have been deposited using a DC magnetron sputtering system with a S-gun configuration, and have been characterized through X-ray diffraction, electrical conductivity, and Hall mobility measurements. The influence of the deposition parameters on both the resistivity of the Mo and on the contact resistivity of the Mo/CuInSe{sub 2}/Mo structure has been studied. Values of resistivity ranging from 1.2x10{sup -5} to 36x10{sup -5} {Omega} cm and of contact resistivity ranging from 0.025 to 0.15 {Omega} cm{sup 2} were found

  20. Powder Metallurgy Fabrication of Molybdenum Accelerator Target Disks

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Richard Andrew [ORNL; Kiggans Jr, James O [ORNL; Bryan, Chris [ORNL; Nunn, Stephen D [ORNL; Parten, Randy J [ORNL

    2015-12-01

    Powder metallurgy approaches for the fabrication of accelerator target disks are being examined to support the development of Mo-99 production by NorthStar Medical Technologies, LLC. An advantage of powder metallurgy is that very little material is wasted and at present, dense, quality parts are routinely produced from molybdenum powder. The proposed targets, however, are thin wafers, 29 mm in diameter with a thickness of 0.5 mm, with very stringent dimensional tolerances. Although tooling can be machined to very high tolerance levels, the operations of powder feed, pressing and sintering involve complicated mechanisms, each of which affects green density and shrinkage, and therefore the dimensions and shape of the final product. Combinations of powder morphology, lubricants and pressing technique have been explored to produce target disks with minimal variations in thickness and little or no distortion. In addition, sintering conditions that produce densities for optimum target dissolvability are being determined.

  1. Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation.

    Science.gov (United States)

    Zhu, Gaohua; Liu, Jun; Zheng, Qiye; Zhang, Ruigang; Li, Dongyao; Banerjee, Debasish; Cahill, David G

    2016-10-21

    Thermal conductivity of two-dimensional (2D) materials is of interest for energy storage, nanoelectronics and optoelectronics. Here, we report that the thermal conductivity of molybdenum disulfide can be modified by electrochemical intercalation. We observe distinct behaviour for thin films with vertically aligned basal planes and natural bulk crystals with basal planes aligned parallel to the surface. The thermal conductivity is measured as a function of the degree of lithiation, using time-domain thermoreflectance. The change of thermal conductivity correlates with the lithiation-induced structural and compositional disorder. We further show that the ratio of the in-plane to through-plane thermal conductivity of bulk crystal is enhanced by the disorder. These results suggest that stacking disorder and mixture of phases is an effective mechanism to modify the anisotropic thermal conductivity of 2D materials.

  2. A New Method for Preparation of Nanocrystalline Molybdenum Nitride

    Institute of Scientific and Technical Information of China (English)

    SHEN Long-Hai; CUI Qi-Liang; ZHANG Jian; LI Xue-Fei; ZHOU Qiang; ZOU Guang-Tian

    2005-01-01

    @@ Nanocrystalline molybdenum nitride (γ-Mo2N) with the cubic structure is prepared by the direct-current arc discharge method in N2 gas, using metal Mo or W rod as a cathode. The x-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to characterize the product. It is found that the conversion of Mo to γ-Mo2N and affinity of Mo to N2 are determined by the nitrogen pressur e. Moreover, we compare the effect of Mo and W rod as a cathode for preparing γ-Mo2N. The average size of γ-Mo2N particles is about 5nm. The rapid quenching mechanism can be used to explain the formation of nanocrystalline γ-Mo2N.

  3. Simple Formation of Nanostructured Molybdenum Disulfide Thin Films by Electrodeposition

    Directory of Open Access Journals (Sweden)

    S. K. Ghosh

    2013-01-01

    Full Text Available Nanostructured molybdenum disulfide thin films were deposited on various substrates by direct current (DC electrolysis form aqueous electrolyte containing molybdate and sulfide ions. Post deposition annealing at higher temperatures in the range 450–700°C transformed the as-deposited amorphous films to nanocrystalline structure. High temperature X-ray diffraction studies clearly recorded the crystal structure transformations associated with grain growth with increase in annealing temperature. Surface morphology investigations revealed featureless structure in case of as-deposited surface; upon annealing it converts into a surface with protruding nanotubes, nanorods, or dumbbell shape nanofeatures. UV-visible and FTIR spectra confirmed about the presence of Mo-S bonding in the deposited films. Transmission electron microscopic examination showed that the annealed MoS2 films consist of nanoballs, nanoribbons, and multiple wall nanotubes.

  4. Plastic anisotropy of straight and cross rolled molybdenum sheets

    Energy Technology Data Exchange (ETDEWEB)

    Oertel, C.-G. [Institut fuer Strukturphysik, Technische Universitaet Dresden, D-01062 Dresden (Germany)], E-mail: oertel@physik.tu-dresden.de; Huensche, I.; Skrotzki, W. [Institut fuer Strukturphysik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Knabl, W.; Lorich, A.; Resch, J. [PLANSEE Metall GmbH, A-6600 Reutte, Tyrol (Austria)

    2008-06-15

    The microstructure, texture and mechanical properties of molybdenum sheets produced by different rolling processes were investigated by orientation imaging in the scanning electron microscope, X-ray diffraction and tensile tests, respectively. For comparable recrystallization degree of the sheets investigated, straight rolling with low reduction ratio produces {alpha}-fiber textures with a maximum at {l_brace}100{r_brace} <110>. At higher rolling degrees the maximum shifts to {l_brace}112{r_brace} <110>. Cross rolling increases the rotated cube component {l_brace}100{r_brace} <110>. The strong differences in the texture measured are reflected in the plastic anisotropy characterized by differences in the yield stress and Lankford parameter which were measured along directions in the rolling plane at angles of 0 deg., 45 deg. and 90 deg. with the rolling direction. The Taylor-Bishop-Hill theory is used successfully to qualitatively explain the plastic anisotropy.

  5. Graphene and molybdenum disulfide hybrids: synthesis and applications

    Directory of Open Access Journals (Sweden)

    Nanjundan Ashok Kumar

    2015-06-01

    Full Text Available Graphene and related inorganic two-dimensional (2D nanomaterials are an exceptional class of compounds with exotic properties that are technologically intriguing. While graphene itself is chemically inert and a gapless semimetal, its isostructural analog, molybdenum disulfide (MOS2 is chemically versatile with band gaps, thereby finding significant use in a myriad of applications. Although these 2D nanomaterials individually possess tremendous authority for various applications, the combination of these materials in the recent past has created a new paradigm in emerging applications. Here, we summarize the current state-of-the-art and progress over the past three years on the development of hybrids of these layered materials. We highlight their pivotal role in electrochemical energy storage, sensing, hydrogen generation by photochemical water splitting and electronic device applications such as field-effect transistors. Perspectives on the challenges and opportunities for the exploration of these 2D layered hybrid materials are put forward.

  6. Advances in Thermionic Cathode of Tungsten and Molybdenum

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungsten, La-Mo cathode has higher emission current density at lower temperature, but it has poor emission stability. In order to improve the emission stability, systematical study on the emission mechanism of La-Mo cathode has been carried out. The life of La-Mo cathode has been improved and has achieved 1400 h, which exceeds the minimum life for practical uses (1000 h). As another alternative for thoriated tungsten cathode, Y-Mo cathode has shown better performance. The thermionic emission capability of Y-Mo cathode is between that of La-Mo cathode and Th-W cathode.

  7. Spreading of Viscous Liquids at High Temperature: Silicate Glasseson Molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Esteban, Sonia; Saiz, Eduardo; Moya, Jose S.; Tomsia,Antoni P.

    2004-12-15

    The spreading of Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. By controlling the oxygen activity in the furnace, spreading can take place under reactive or non-reactive conditions. As the nucleation of the reaction product under reactive conditions is slow in comparison to the spreading kinetics, in both cases the glass front moves on the metal surface with similar spreading velocities. Spreading can be described using a molecular dynamics model where the main contribution to the wetting activation energy comes from the viscous interactions in the liquid. Enhanced interfacial diffusions in low-oxygen activities (reactive cases) form triple-line ridges that can pin the wetting front and cause a stick-slip motion.

  8. Extraction of Molybdenum from Molybdenite Concentrates with Hydrometallurgical Processing

    Science.gov (United States)

    Jiang, Kaixi; Wang, Yufang; Zou, Xiaoping; Zhang, Lei; Liu, Sanping

    2012-11-01

    Molybdenite concentrates are usually treated by roasting, but low-concentration SO2 pollution is an associated problem. A hydrometallurgical process with pressure oxidation leaching (POX) and solvent extraction (SX) was developed in recent years. During POX, the oxidation of molybdenum (Mo) is above 98%. More than 95% of the rhenium (Re) and 15% to 20% of the Mo are leached into solution. The sulfur in the concentrate is converted to H2SO4, which results in high acidity of the solution. SX was used to recover the Re and Mo from the solution. The extraction of Re and Mo were above 98%. The loaded organic reagent is stripped with ammonia. More than 98% of the Mo can be stripped from the organic phase. Compared with the roasting process, the total recovery of Mo increased from 93% to 97% and that of Re from 60% to 90% when POX and SX are utilized.

  9. Towards slide enhancement with the titanium-molybdenum wire?

    Science.gov (United States)

    Thiry, Pol; Barthélémi, Stéphane

    2010-12-01

    This study aims to improve the tribological properties of titanium-molybdenum wire. Following an analysis of the wire/bracket/ligation friction parameters and an overview of the technological research into means of reducing such friction,we set up several types of surface treatment in the laboratory by physical deposition in the vapor phase and using cold plasma technology. The specimens obtained underwent two types of tribological tests and were then subjected to traction and bending tests in order to determine the variations in their mechanical properties induced by the different types of treatment. For purposes of comparison, all the tests were conducted on untreated wire, TMA® Low-friction® wire and stainless steel wire and with two types of elastomeric ties. We were able to demonstrate some remarkable slide performances obtained using cold plasma nitriding while preserving the mechanical properties. A significant difference was observed relative to the other surface treatments.

  10. Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation

    Science.gov (United States)

    Zhu, Gaohua; Liu, Jun; Zheng, Qiye; Zhang, Ruigang; Li, Dongyao; Banerjee, Debasish; Cahill, David G.

    2016-01-01

    Thermal conductivity of two-dimensional (2D) materials is of interest for energy storage, nanoelectronics and optoelectronics. Here, we report that the thermal conductivity of molybdenum disulfide can be modified by electrochemical intercalation. We observe distinct behaviour for thin films with vertically aligned basal planes and natural bulk crystals with basal planes aligned parallel to the surface. The thermal conductivity is measured as a function of the degree of lithiation, using time-domain thermoreflectance. The change of thermal conductivity correlates with the lithiation-induced structural and compositional disorder. We further show that the ratio of the in-plane to through-plane thermal conductivity of bulk crystal is enhanced by the disorder. These results suggest that stacking disorder and mixture of phases is an effective mechanism to modify the anisotropic thermal conductivity of 2D materials. PMID:27767030

  11. Development of Solvent Extraction Approach to Recycle Enriched Molybdenum Material

    Energy Technology Data Exchange (ETDEWEB)

    Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Brown, M. Alex [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Sen, Sujat [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Bowers, Delbert L. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Wardle, Kent [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Pupek, Krzysztof Z. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Dzwiniel, Trevor L. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Pereira, Candido [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Krumdick, Gregory K. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    Argonne National Laboratory, in cooperation with Oak Ridge National Laboratory and NorthStar Medical Technologies, LLC, is developing a recycling process for a solution containing valuable Mo-100 or Mo-98 enriched material. Previously, Argonne had developed a recycle process using a precipitation technique. However, this process is labor intensive and can lead to production of large volumes of highly corrosive waste. This report discusses an alternative process to recover enriched Mo in the form of ammonium heptamolybdate by using solvent extraction. Small-scale experiments determined the optimal conditions for effective extraction of high Mo concentrations. Methods were developed for removal of ammonium chloride from the molybdenum product of the solvent extraction process. In large-scale experiments, very good purification from potassium and other elements was observed with very high recovery yields (~98%).

  12. Highly enantioselective hydrogenation of N-aryl imines derived from acetophenones by using Ru-pybox complexes under hydrogenation or transfer hydrogenation conditions in isopropanol.

    Science.gov (United States)

    Menéndez-Pedregal, Estefanía; Vaquero, Mónica; Lastra, Elena; Gamasa, Pilar; Pizzano, Antonio

    2015-01-07

    The asymmetric reduction of N-aryl imines derived from acetophenones by using Ru complexes bearing both a pybox (2,6-bis(oxazoline)pyridine) and a monodentate phosphite ligand has been described. The catalysts show good activity with a diverse range of substrates, and deliver the amine products in very high levels of enantioselectivity (up to 99 %) under both hydrogenation and transfer hydrogenation conditions in isopropanol. From deuteration studies, a very different labeling is observed under hydrogenation and transfer hydrogenation conditions, which demonstrates the different nature of the hydrogen source in both reactions.

  13. Soil organic matter regulates molybdenum storage and mobility in forests

    Science.gov (United States)

    Marks, Jade A; Perakis, Steven; King, Elizabeth K; Pett-Ridge, Julie

    2015-01-01

    The trace element molybdenum (Mo) is essential to a suite of nitrogen (N) cycling processes in ecosystems, but there is limited information on its distribution within soils and relationship to plant and bedrock pools. We examined soil, bedrock, and plant Mo variation across 24 forests spanning wide soil pH gradients on both basaltic and sedimentary lithologies in the Oregon Coast Range. We found that the oxidizable organic fraction of surface mineral soil accounted for an average of 33 %of bulk soil Mo across all sites, followed by 1.4 % associated with reducible Fe, Al, and Mn-oxides, and 1.4 % in exchangeable ion form. Exchangeable Mo was greatest at low pH, and its positive correlation with soil carbon (C) suggests organic matter as the source of readily exchangeable Mo. Molybdenum accumulation integrated over soil profiles to 1 m depth (τMoNb) increased with soil C, indicating that soil organic matter regulates long-term Mo retention and loss from soil. Foliar Mo concentrations displayed no relationship with bulk soil Mo, and were not correlated with organic horizon Mo or soil extractable Mo, suggesting active plant regulation of Mo uptake and/or poor fidelity of extractable pools to bioavailability. We estimate from precipitation sampling that atmospheric deposition supplies, on average, over 10 times more Mo annually than does litterfall to soil. In contrast, bedrock lithology had negligible effects on foliar and soil Mo concentrations and on Mo distribution among soil fractions. We conclude that atmospheric inputs may be a significant source of Mo to forest ecosystems, and that strong Mo retention by soil organic matter limits ecosystem Mo loss via dissolution and leaching pathways.

  14. Molybdenum Evidence for Inherited Planetary Scale Isotope Heterogeneity of the Protosolar Nebula

    CERN Document Server

    Dauphas, N; Reisberg, L

    2001-01-01

    Isotope anomalies provide important information about early solar system evolution. Here we report molybdenum isotope abundances determined in samples of various meteorite classes. There is no fractionation of molybdenum isotopes in our sample set within 0.1 permil and no contribution from the extinct radionuclide 97Tc at mass 97 (97Tc/92Mo<3E-6). Instead, we observe clear anomalies in bulk iron meteorites, mesosiderites, pallasites, and chondrites characterized by a coupled excess in p- and r- or a mirror deficit in s-process nuclides (Mo-HL). This large scale isotope heterogeneity of the solar system observed for molybdenum must have been inherited from the interstellar environment where the sun was born, illustrating the concept of ``cosmic chemical memory''. The presence of molybdenum anomalies is used to discuss the filiation between planetesimals.

  15. Thermal treatment of solution-processed nano-sized thin films of molybdenum oxide

    Science.gov (United States)

    Ganchev, M.; Sendova-Vassileva, M.; Popkirov, G.; Vitanov, P.

    2016-10-01

    A solution based deposition method to form nano-sized thin films of molybdenum oxide suitable for photovoltaic device applications is presented. The samples were deposited by spin-coating from molybdenum metal organic precursor solution on soda lime glass substrates. The influence of the process parameters such as spinning regime and concentration of the precursor solutions on the thickness and morphology of the films were investigated. The thermal decomposition of the molybdenum precursor and oxide formation were investigated by differential scanning calorimetry and characteristic patterns showed transitions up to 300oC followed by a zone of stability. Optical spectroscopy measurements in the wavelength range from 300 to 1800 nm presented an increase in transparency when temperature of annealing was raised up to 400oC. Raman scattering analysis revealed the presence of mixed molybdenum oxides. Measurements of the electrical conductivity were performed by the 4-point method.

  16. Interface confined hydrogen evolution reaction in zero valent metal nanoparticles-intercalated molybdenum disulfide

    Science.gov (United States)

    Chen, Zhongxin; Leng, Kai; Zhao, Xiaoxu; Malkhandi, Souradip; Tang, Wei; Tian, Bingbing; Dong, Lei; Zheng, Lirong; Lin, Ming; Yeo, Boon Siang; Loh, Kian Ping

    2017-01-01

    Interface confined reactions, which can modulate the bonding of reactants with catalytic centres and influence the rate of the mass transport from bulk solution, have emerged as a viable strategy for achieving highly stable and selective catalysis. Here we demonstrate that 1T′-enriched lithiated molybdenum disulfide is a highly powerful reducing agent, which can be exploited for the in-situ reduction of metal ions within the inner planes of lithiated molybdenum disulfide to form a zero valent metal-intercalated molybdenum disulfide. The confinement of platinum nanoparticles within the molybdenum disulfide layered structure leads to enhanced hydrogen evolution reaction activity and stability compared to catalysts dispersed on carbon support. In particular, the inner platinum surface is accessible to charged species like proton and metal ions, while blocking poisoning by larger sized pollutants or neutral molecules. This points a way forward for using bulk intercalated compounds for energy related applications. PMID:28230105

  17. FY16 Status Report for the Uranium-Molybdenum Fuel Concept

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, Wendy D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Doherty, Ann L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Montgomery, Robert O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Omberg, Ronald P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Mark T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Webster, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-22

    The Fuel Cycle Research and Development program of the Office of Nuclear Energy has implemented a program to develop a Uranium-Molybdenum metal fuel for light water reactors. Uranium-Molybdenum fuel has the potential to provide superior performance based on its thermo-physical properties. With sufficient development, it may be able to provide the Light Water Reactor industry with a melt-resistant, accident-tolerant fuel with improved safety response. The Pacific Northwest National Laboratory has been tasked with extrusion development and performing ex-reactor corrosion testing to characterize the performance of Uranium-Molybdenum fuel in both these areas. This report documents the results of the fiscal year 2016 effort to develop the Uranium-Molybdenum metal fuel concept for light water reactors.

  18. Influence of organic amendments on the mobilization of molybdenum in soils

    Energy Technology Data Exchange (ETDEWEB)

    Calderone, S.J.; Frankenberger, W.T. Jr. (Univ. of California, Riverside (USA))

    1990-08-01

    Recent attention has been focused on toxic levels of selenium (Se), arsenic, chromium, mercury, boron and molybdenum (Mo) accumulating in saline agricultural evaporation pond waters. Although this is an effective disposal practice for agricultural drainage water, the ponds attract wildlife and waterfowl which may create adverse environmental risks. There is a major concern with the Mo content in these saline waters and its effect on the upper food chain. Molybdenum can be fixed in soil or liberated into soil solution and become available for biotic uptake. Molybdenum is a metallic element that can exist in different valences and oxidation states. Oxidation and alkaline conditions favor Mo mobility. The objective of this study was to determine the effect of various organic materials on the solubilization and mobilization of molybdenum in soil.

  19. RECYCLING TECHNOLOGY INTO INDUSTRIAL TURNOVER OF BISMUTH AND MOLYBDENUM FROM DEAD CATALYST

    Directory of Open Access Journals (Sweden)

    O. S. Komarov

    2013-01-01

    Full Text Available The technology of separate extraction of bismuth and molybdenum from spent catalyst was presented and information on the effectiveness of its use in a composition of comprehensive modifier in the iron-carbon alloy was given.

  20. Nuclear emulsion with molybdenum filling for observation of $\\beta\\beta$ decay

    CERN Document Server

    Ashitkov, V D; Barabash, A S; Bradnova, V Ya; Chernyavsky, M M; Konovalov, S I; Okat'eva, N M; Orlova, G I; Polukhina, N G; Pozharova, E A; Smirnitsky, V A; Starkov, N I; Vladimirov, M S; Umatov, V I

    2010-01-01

    The usage of nuclear emulsion with molybdenum filling for observation of $\\beta\\beta$ decay are shown to be possible. Estimates for 1 kg of $^{100}$Mo with zero background give the sensitivity for the $0\

  1. Mapping the formation areas of giant molybdenum blue clusters: a spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Botar, Bogdan; Ellern, Arkady; Kogerler, Paul

    2012-05-18

    The self-assembly of soluble molybdenum blue species from simple molybdate solutions has primarily been associated with giant mixed-valent wheel-shaped cluster anions, derived from the {MoV/VI154/176} archetypes, and a {MoV/VI368} lemon-shaped cluster. The combined use of Raman spectroscopy and kinetic precipitation as self-assembly monitoring techniques and single-crystal X-ray diffraction is key to mapping the realm of molybdenum blue species by establishing spherical {MoV/VI102}-type Keplerates as an important giant molybdenum blue-type species. We additionally rationalize the empirical effect of reducing agent concentration on the formation of all three relevant skeletal types: wheel, lemon and spheres. Whereas both wheels and the lemon-shaped {MoV/VI368} cluster are obtained from weakly reduced molybdenum blue solutions, considerably higher reduced solutions lead to {MoV/VI102}-type Keplerates.

  2. Edge eigen-stress and eigen-displacement of armchair molybdenum disulfide nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Quan; Li, Xi [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A., E-mail: volinsky@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States); Su, Yanjing, E-mail: yjsu@ustb.edu.cn [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China)

    2017-05-10

    Edge effects on mechanical properties of armchair molybdenum disulfide nanoribbons were investigated using first principles calculations. The edge eigen-stress model was applied to explain the relaxation process of forming molybdenum disulfide nanoribbon. Edge effects on surface atoms fluctuation degree were obtained from each fully relaxed nanoribbon with different width. Changes of the relaxed armchair molybdenum disulfide nanoribbons structure can be expressed using hexagonal perimeters pattern. Based on the thickness change, relaxed armchair molybdenum disulfide nanoribbons tensile/compression tests were simulated, providing intrinsic edge elastic parameters, such as eigen-stress, Young's modulus and Poisson's ratio. - Highlights: • Edge effects on mechanical properties of armchair MoS{sub 2} nanoribbons were investigated. • Structure changes of different width armchair MoS{sub 2} nanoribbons were obtained. • Tensile/compressive tests were conducted to determine elastic constants. • Mechanical properties are compared for two and three dimensional conditions.

  3. Molybdenum and tungsten nanostructures and methods for making and using same

    Science.gov (United States)

    Kotaro, Sasaki; Chen, Wei-Fu; Muckerman, James T; Adzic, Radoslav R

    2015-01-06

    The present invention provides molybdenum and tungsten nanostructures, for example, nanosheets and nanoparticles, and methods of making and using same, including using such nanostructures as catlysts for hydrogen evolution reactions.

  4. The Application of Gravity and CSAMT Survey on Baishan Molybdenum Deposit, Hami, Xinjiang,China

    Science.gov (United States)

    Yang, Y.; Lu, H.; Zhang, K.

    2014-12-01

    Baishan molybdenum deposit is located in the eastern Tianshan Carboniferous rift at Hami, Xinjiang, China, where exposed upper Carboniferous Gandun formation. Molybdenum ore appeared at thermal contact metamorphism hornfelsed banded quartz stockwork in the concealed porphyritic granite top, Potassium and metal sulfide mineralization existed in the top of concealed rockbody.The Baishan molybdenum ore bodies were delineated 2700 meters long and 40 meters thickness, with molybdenum @ 0.59%. The main orebody shows in stratoid, small orebody appears in lenticular and vein.In order to predict potential resources, we proposes a combined method of CSAMT and GS technology,and has applied it to the survey of concealed molybdenum deposit in the Baishan.This combind method can explore to larger depths, discriminate anomalies well and has higher resolution to deep objects, thus it is an efficient tool for surveys.By drilling, we found there exsit a hidden granite body in 1400 meters deep of Hami Baishan molybdenum mine, it confirmed that Baishan molybdenum mine is a porphyry molybdenum ore. Cataclastic hornfelsed zone in the coping granite are the product of heat contact metamorphism, the ore materials are mainly derived from deep magma hydrothermal solution. The CSAMT and Gravity Survey were able to reflect the space and intrusive boundary in rough of buried granite body clearly, deep hidden granite showed high-resistivity and high-gravity anomaly and the low-resistivity anomaly distributied around them, drilling verified that 200-2500Ω low-resistivity anomaly range at top of high-resistivity corresponded to the molybdenum ore horizon. Line 15 of southern section shows two low resistance anomaly zone, and the surface of them is corresponding to the granite and intrusive contact parts,inferring it was caused by the fault structure.In granite gravity anomaly is obviously high and the width is about 560m,Δg residual value is 400 × 10-8m/s2. According to the control of

  5. Arc-related porphyry molybdenum deposit model: Chapter D in Mineral deposit models for resource assessment

    Science.gov (United States)

    Taylor, Ryan D.; Hammarstrom, Jane M.; Piatak, Nadine M.; Seal, Robert R., II

    2012-01-01

    This report provides a descriptive model for arc-related porphyry molybdenum deposits. Presented within are geological, geochemical, and mineralogical characteristics that differentiate this deposit type from porphyry copper and alkali-feldspar rhyolite-granite porphyry molybdenum deposits. The U.S. Geological Survey's effort to update existing mineral deposit models spurred this research, which is intended to supplement previously published models for this deposit type that help guide mineral-resource and mineral-environmental assessments.

  6. Material and Energy Flows Associated with Select Metals in GREET 2. Molybdenum, Platinum, Zinc, Nickel, Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dai, Qiang [Argonne National Lab. (ANL), Argonne, IL (United States); Sullivan, John L. [Argonne National Lab. (ANL), Argonne, IL (United States); Kelly, Jarod C. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    In this work, we analyzed the material and energy consumption from mining to production of molybdenum, platinum, zinc, and nickel. We also analyzed the production of solar- and semiconductor-grade silicon. We described new additions to and expansions of the data in GREET 2. In some cases, we used operating permits and sustainability reports to estimate the material and energy flows for molybdenum, platinum, and nickel, while for zinc and silicon we relied on information provided in the literature.

  7. Note: Laser-cut molybdenum grids for a retarding field energy analyzer

    Science.gov (United States)

    Landheer, K.; Kobelev, A. A.; Smirnov, A. S.; Bosman, J.; Deelen, S.; Rossewij, M.; de Waal, A. C.; Poulios, I.; Benschop, A. F.; Schropp, R. E. I.; Rath, J. K.

    2017-06-01

    A retarding field energy analyzer (RFEA) with grids created by laser-cutting a honeycomb mesh in a 50 μm thick molybdenum foil is presented. The flat grids span an area of 1 cm2 and have high transmission (20 μm wide walls between 150 μm wide meshes). The molybdenum grids were tested in a 3-grid RFEA configuration with an analyzer depth of 0.87 mm.

  8. Active carbon supported molybdenum carbides for higher alcohols synthesis from syngas

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Chiarello, Gian Luca; Christensen, Jakob Munkholt

    This work provides an investigation of the high pressure CO hydrogenation to higher alcohols on K2CO3 promoted active carbon supported molybdenum carbide. Both activity and selectivity to alcohols over supported molybdenum carbides increased significantly compared to bulk carbides in literatures....... spectroscopy were applied for determining the carburization temperature and evaluating the composition of the carbide clusters of different samples through determinations of the Mo-C and Mo-Mo coordination numbers....

  9. Synthesis and Characterization of Vanadium Molybdenum Oxynitrides Nanoparticles in the Channels of MCM-41

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cunman; XU Zheng; LIU Qian

    2005-01-01

    Vanaadium molybdenum oxynitrides nanoparticles were synthesized successfully in the channels of MCM-41 after surface modification, vacuum co-impregnation ami nitridation technology. The products were investigated by nitrogen sorption measurement, X-ray powder diffraction ( XRD ), high-resolution transmission electron microscopy (HRTEM), energy dispersive analysis of X-rays (EDAX) and CNH element analysis. The investigation results show that superfine nanoparticles of vanadium molybdenum oxynitrides exist in the channels of MCM-41.

  10. Molybdenum-containing acidic catalysts to convert cellulosic biomass to glycolic acid

    KAUST Repository

    Han, Yu

    2014-09-30

    Embodiments of the present invention include methods and compositions related to catabolic conversion of cellulosic biomass to glycolic acid using molybdenum-containing acidic catalysts. The invention includes the use of heteropoly and isopoly acids and salts as the molybdenum-containing multi-functional catalysts for biomass conversion. In embodiments of the invention, the reactions employ successive hydrolysis, retro-aldol fragmentation, and selective oxidation in a noble metal-free system.

  11. Toxicity of molybdenum and its trace analysis in animal tissues and plants.

    Science.gov (United States)

    Abbasi, S A

    1981-01-01

    A sensitive, selective, rapid and reproducible method is presented for the analysis of submicrogram levels of molybdenum in animal tissues (Liver) and plants. The method is based on solvent extraction of Molybdenum (VI) using isoamyl alcohol solution of N-o-tolyl-o-methoxy-benzohydroxamic acid at pH 1.5-2.5, and subsequent spectrophotometric determination of the yellow extract at 350 nm.

  12. Studies of the mechanism of the olefin metathesis reaction and the process of active site formation on photoreduced molybdenum-silicate catalysts. I. Mechanism of formation of molybdenum-carbene intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Elev, I.V.; Shelimov, B.N.; Kazanskii, V.B.

    1987-10-01

    The products of the initial stages of the reaction of ethylene and propylene with Mo/sup 4 +/ ions in photoreduced molybdenum-silicate olefin metathesis catalysts have been studied by mass spectroscopy. The reaction of C/sub 2/H/sub 4/ with Mo/sup 4 +/ has been found to yield propylene, whereas interaction of C/sub 3/H/sub 6/ with Mo/sup 4 +/ gives a superequilibrium concentration of butenes and a small amount of pentenes. A significant kinetic isotope effect for the metathesis reaction was observed upon substitution of C/sub 3/H/sub 6/ by C/sub 3/D/sub 6/. The results can be interpreted in terms of a stepwise mechanism involving carbene intermediates, which are formed via isomerization of surface-bound ..pi..-complexes of olefins with Mo/sup 4 +/ ions as a result of intramolecular 1,2-H atom transfer.

  13. Correlation of optical properties with the fractal microstructure of black molybdenum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Enrique; Gonzalez, Federico [Area de Energia, Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico, D.F. 09340 (Mexico); Rodriguez, Eduardo [Area de Computacion y Sistemas, Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico, D.F. 09340 (Mexico); Alvarez-Ramirez, Jose, E-mail: jjar@xanum.uam.mx [Area de Energia, Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico, D.F. 09340 (Mexico)

    2010-01-01

    Coating is commonly used for improving the optical properties of surfaces for solar collector applications. The coating morphology depends on the deposition conditions, and this determines the final optical characteristics. Coating morphologies are irregular and of fractal nature, so a suitable approach for its characterization should use methods borrowed from fractal analysis. The aim of this work is to study the fractal characteristics of black molybdenum coatings on copper and to relate the fractal parameters to the optical properties. To this end, coating surfaces were prepared via immersion in a solution of ammonium paramolybdate for different deposition periods. The fractal analysis was carried out for SEM and AFM images of the coating surface and the fractal properties were obtained with a recently developed high-dimensional extension of the well-known detrended fluctuation analysis (DFA). The most salient parameter drawn from the application of the DFA is the Hurst index, a parameter related to the roughness of the coating surface, and the multifractality index, which is related to the non-linearity features of the coating morphology. The results showed that optical properties, including absorptance and emittance, are decreasing functions of the Hurst and multifractality indices. This suggests that coating surfaces with high absorptance and emittance values are related to complex coating morphologies conformed within a non-linear structure.

  14. Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

    Science.gov (United States)

    Wagner, Meghan; Chappaz, Anthony; Lyons, Timothy W.

    2017-06-01

    Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth's history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain concerning the geochemical mechanism(s) leading to Mo burial in anoxic sediments. Better characterization of Mo speciation should provide mechanistic insight into sedimentary Mo accumulation, and therefore in this study we investigate Mo speciation from both modern (Castle Lake, USA) and ancient (Doushantuo Formation, China) environments using X-ray Absorption Near Edge Structure (XANES) spectroscopy. By utilizing a series of laboratory-synthesized oxythiomolybdate complexes-many containing organic ligands-we expand the number of available standards to encompass a greater range of known Mo chemistry and test the linkage between Mo and total organic carbon (TOC). In weakly euxinic systems ([H2S(aq)] < 11 μM), or where sulfide is restricted to pore waters, natural samples are best represented by a linear combination of MoO3, MoOxS4-x2- (intermediate thiomolybdates), and [MoOx(cat)4-x]2- (cat = catechol, x = 2 or 3). These results suggest a revised model for how Mo accumulates in weakly sulfidic sediments, including a previously unrecognized role for organic matter in early sequestration of Mo and a de-emphasized importance for MoS42- (tetrathiomolybdate).

  15. Nanocomposites of Molybdenum Disulfide/Methoxy Polyethylene Glycol-co-Polypyrrole for Amplified Photoacoustic Signal.

    Science.gov (United States)

    Lee, Hohyeon; Kim, Haemin; Nguyen, Thang Phan; Chang, Jin Ho; Kim, Soo Young; Kim, Hyuncheol; Kang, Eunah

    2016-11-02

    Photoacoustic activity is the generation of an ultrasonic signal via thermal expansion or bubble formation, stimulated by laser irradiation. Photoacoustic nanoplatforms have recently gained focus for application in bioelectric interfaces. Various photoacoustic material types have been evaluated, including gold nanoparticles, semiconductive π-conjugating polymers (SP), etc. In this study, surfactant-free methoxy-polyethylene glycol-co-polypyrrole copolymer (mPEG-co-PPyr) nanoparticles (NPs) and mPEG-co-PPyr NP/molybdenum disulfide (mPEG-co-PPyr/MoS2) nanocomposites (NCs) were prepared and their photoacoustic activity was demonstrated. The mPEG-co-PPyr NPs and mPEG-co-PPyr/MoS2 NCs both showed photoacoustic signal activity. The mPEG-co-PPyr/MoS2 NCs presented a higher photoacoustic signal amplitude at 700 nm than the mPEG-co-PPyr NPs. The enhanced photoacoustic activity of the mPEG-co-PPyr/MoS2 NCs might be attributed to heterogeneous interfacial contact between mPEG-co-PPyr and the MoS2 nanosheets due to complex formation. Laser ablation of MoS2 might elevate the local temperature and facilitate the thermal conductive transfer in the mPEG-co-PPyr/MoS2 NCs, amplifying PA signal. Our study, for the first time, demonstrates enhanced PA activity in SP/transition metal disulfide (TMD) composites as photoacoustic nanoplatforms.

  16. Molybdenum-Loaded Anatase TiO2 Nanoparticles With Enhanced Optoelectronics Properties

    Science.gov (United States)

    Bargougui, R.; Bouazizi, N.; Ammar, S.; Azzouz, A.

    2017-01-01

    The structural, optical and electrical properties of molybdenum nanoparticles (Mo-NPs)-loaded anatase TiO2 were investigated using x-ray diffraction, UV-Vis diffuse reflectance, and Fourier transform infrared and complex impedance spectroscopy. x-ray diffraction showed that Mo-NPs incorporation induced a decrease in particle size from 30 nm to 21 nm of TiO2 and TiO2-Mo, respectively, producing a slight structure expansion. Mo-NPs dispersion resulted in a slight decrease in the optical band gap energy from 3.85 eV to 3.51 eV. Slight shifts towards higher wavelengths were attributed to the change in the acceptor capacity level induced by Mo-NPs. In addition, the ac impedance studies show the effect of Mo-NPs incorporation that appeared to be responsible for conductance of enhancement. The conduction mechanism is based on space charge-limited current via deep levels with different energy positions in the band gap. The temperature dependence of electrical properties showed that both capacitance and conductance of TiO2-Mo samples increased with increasing temperature. At low frequency, the relaxation phenomenon is related to the surface effect. The results will be beneficial to further developing titanium dioxide photo-catalysts.

  17. Molybdenum and phosphorus interact to constrain asymbiotic nitrogen fixation in tropical forests.

    Directory of Open Access Journals (Sweden)

    Nina Wurzburger

    Full Text Available Biological di-nitrogen fixation (N(2 is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P is thought to limit N(2 fixation in many tropical soils, yet both molybdenum (Mo and P are crucial for the nitrogenase reaction (which catalyzes N(2 conversion to ammonia and cell growth. We have limited understanding of how and when fixation is constrained by these nutrients in nature. Here we show in tropical forests of lowland Panama that the limiting element on asymbiotic N(2 fixation shifts along a broad landscape gradient in soil P, where Mo limits fixation in P-rich soils while Mo and P co-limit in P-poor soils. In no circumstance did P alone limit fixation. We provide and experimentally test a mechanism that explains how Mo and P can interact to constrain asymbiotic N(2 fixation. Fixation is uniformly favored in surface organic soil horizons--a niche characterized by exceedingly low levels of available Mo relative to P. We show that soil organic matter acts to reduce molybdate over phosphate bioavailability, which, in turn, promotes Mo limitation in sites where P is sufficient. Our findings show that asymbiotic N(2 fixation is constrained by the relative availability and dynamics of Mo and P in soils. This conceptual framework can explain shifts in limitation status across broad landscape gradients in soil fertility and implies that fixation depends on Mo and P in ways that are more complex than previously thought.

  18. Molybdenum and phosphorus interact to constrain asymbiotic nitrogen fixation in tropical forests.

    Science.gov (United States)

    Wurzburger, Nina; Bellenger, Jean Philippe; Kraepiel, Anne M L; Hedin, Lars O

    2012-01-01

    Biological di-nitrogen fixation (N(2)) is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P) is thought to limit N(2) fixation in many tropical soils, yet both molybdenum (Mo) and P are crucial for the nitrogenase reaction (which catalyzes N(2) conversion to ammonia) and cell growth. We have limited understanding of how and when fixation is constrained by these nutrients in nature. Here we show in tropical forests of lowland Panama that the limiting element on asymbiotic N(2) fixation shifts along a broad landscape gradient in soil P, where Mo limits fixation in P-rich soils while Mo and P co-limit in P-poor soils. In no circumstance did P alone limit fixation. We provide and experimentally test a mechanism that explains how Mo and P can interact to constrain asymbiotic N(2) fixation. Fixation is uniformly favored in surface organic soil horizons--a niche characterized by exceedingly low levels of available Mo relative to P. We show that soil organic matter acts to reduce molybdate over phosphate bioavailability, which, in turn, promotes Mo limitation in sites where P is sufficient. Our findings show that asymbiotic N(2) fixation is constrained by the relative availability and dynamics of Mo and P in soils. This conceptual framework can explain shifts in limitation status across broad landscape gradients in soil fertility and implies that fixation depends on Mo and P in ways that are more complex than previously thought.

  19. 某钼尾矿氧化钼选矿试验研究%EXPERIMENTAL STUDY ON THE BENEFICIATION OF MOLYBDENUM OXIDE FROM A MOLYBDENUM FLOATATION TAILINGS

    Institute of Scientific and Technical Information of China (English)

    肖骏; 李晓东; 陈代雄; 杨建文; 董艳红

    2016-01-01

    某硫化-氧化混合钼矿生产钼尾矿Mo含量过高造成资源的极大浪费. 试验研究在矿石性质研究的基础上,通过药剂制度和工艺流程的优化确定了尾矿再磨—预先脱泥—氧化钼浮选的工艺流程. 针对氧化钼矿物难选的现象,研究开发了新型两性捕收剂α-氨基酸,实现了对钼酸钙矿物的有效回收. 最终选矿指标:在Mo 尾矿含Mo 0.095%条件下,所得氧化钼精矿含Mo 8.120%,精矿中Mo总回收率达到了77.467%.%Great waste of molybdenum resources was caused by high content of Mo in the molybdenum tailings which was produced from a sulfide-oxidized molybdenum ore .On the basis of the properties of the ore , the technological process including regrinding for tailings-preliminary desliming-floatation of molybdenum oxide was determined through optimization of process and reagents rules .The study developed a new-style amphoteric collector-α-amino acid to re-cycle the refractory calcium molybdate focused on the phenomenon of difficulty to recycling for molybdenum ox -ide.The final index is as following:while the run-of-time ores have 0.34%of Mo , the molybdenum oxide concentrate contains 8.120%Mo, the recovery rate of Mo is 77.467%

  20. Aspects of designing an optimized molybdenum back contact in CIGS-technology

    Energy Technology Data Exchange (ETDEWEB)

    Oertel, Michael; Goetz, Stefan; Haarstrich, Jakob; Metzner, Heinrich; Reisloehner, Udo; Ronning, Carsten; Wesch, Werner [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany)

    2011-07-01

    In Cu(In,Ga)Se{sub 2}(CIGS)-solar cell and module production, the sputtering of the molybdenum back contact is the first step in nearly all process lines. We present our results of experiments to elucidate the different aspects which have to be kept in mind when depositing the molybdenum back contact by dc-magnetron sputtering. These aspects include: I) The adhesion of the molybdenum to the glass substrate as well as the adhesion of the CIGS-layer to the molybdenum, II) electrical conductivity, III) sodium diffusion and IV) the specific contact resistance of the molybdenum to the aluminium doped zinc oxide (Al:ZnO) window layer. We present our three layer design of the back contact which combines an optimized adhesion to both the substrate and the absorber and also a high electrical conductivity. X-ray diffraction measurements (XRD) are employed to characterize each single layer. We also discuss I-U-measurements of CuInSe{sub 2}-solar cells made in a sequential absorber layer process in order to study the sodium transport behaviour of molybdenum back contacts sputtered at different argon sputter pressures. The sodium content in the absorber and the different back contact layers is measured by secondary ion mass spectroscopy (SIMS). A lowest value of the specific contact resistance between the Mo and the Al:ZnO of (1.37{+-}0.14).10{sup 5} {omega}cm{sup 2} was determined.

  1. Numerical Simulation of Rectangular Deep Draw Containers Made from Thin Molybdenum Sheet

    Science.gov (United States)

    Žmindák, M.; Donič, T.; Jurík, P.

    2016-11-01

    The paper presents numerical simulation-FEM variations in the technological and design parameters of deformation at different levels during the plastic deformation of complexly shaped hollow parts of a pure molybdenum sheet in terms of the thermo forming. Variations of the process parameters such as deformation temperature, blank holder force, shape and geometry of the drawbeads, the shape and geometry of the blank thin sheet of the molybdenum metal allow making optimisation procedures for hot forming of the thin molybdenum sheet when the products of these processes have no rotational symmetry. The results of the numerical simulations in programming environments PAM-STAMP 2015 enable implementing the validation of each technological and design elements of the deformation system for an optimal process of plastic deformation of the rotationally asymmetrical hollow containers of the thin molybdenum metal as well as determining the critical deformation and stress zones in the discrete volumes of the molybdenum sheet metal. In the area of allowance, attention is to be paid to the shape and geometry of the drawbeads, friction ratios in the critical zones of deformation and to the aspect of their positive effect on the flow of molybdenum metal to unbalanced holeforming tool to apply the criterion of the maximum allowable wall thinning yield.

  2. Determination of aluminium in molybdenum and tungsten metals, iron, steel and ferrous and non-ferrous alloys with pyrocatechol violet.

    Science.gov (United States)

    Donaldson, E M

    1971-09-01

    A method for determining 0.001-0.10% of aluminium in molybdenum and tungsten metals is described. After sample dissolution, aluminium is separated from the matrix materials by chloroform extraction of its acetylacetone complex, at pH 6.5, from an ammonium acetate-hydrogen peroxide medium, then back-extracted into 12M hydrochloric add. Following separation of most co-extracted elements, except for beryllium and small amounts of chroinium(III) and copper(II), by a combined ammonium pyrrolidincdithiocarbamate-cupfen-on-chlorofonn extraction, aluminium is determined spectrophotometrically with Pyrocatechol Violet at 578 nm. Chromium interferes during colour development but beryllium, in amounts equivalent to the aluminium concentration, does not cause significant error in the results. Interference from copper(II) is eliminated by reduction with ascorbic acid. The proposed method is also applicable to iron, steel, ferrovanadium, and copper-base alloys after preliminary removal of the matrix elements by a mercury cathode separation.

  3. The History of the Discovery of the Molybdenum Cofactor and Novel Aspects of its Biosynthesis in Bacteria.

    Science.gov (United States)

    Leimkühler, Silke; Wuebbens, Margot M; Rajagopalan, K V

    2011-05-01

    Biosynthesis of the molybdenum cofactor in bacteria is described with a detailed analysis of each individual reaction leading to the formation of stable intermediates during the synthesis of molybdopterin from GTP. As a starting point, the discovery of molybdopterin and the elucidation of its structure through the study of stable degradation products are described. Subsequent to molybdopterin synthesis, the molybdenum atom is added to the molybdopterin dithiolene group to form the molybdenum cofactor. This cofactor is either inserted directly into specific molybdoenzymes or is further modified by the addition of nucleotides to the molybdopterin phosphate group or the replacement of ligands at the molybdenum center.

  4. QUANTITY DETERMINATION OF MOLYBDENUM FROM PISUM SATIVUM PLANTS AND THE INFLUENCE OF HEAVY METAL TO CHEMICAL ELEMENTS ACCUMULATION

    Directory of Open Access Journals (Sweden)

    MONICA BUTNARIU

    2013-12-01

    Full Text Available The aim of this study was to test the pea plant as sentinel specie for the heavy metal molybdenum. Evaluation of soil quality after the molybdenum uptake by pea revealed the following results: Pea plant is a bioindicator that concentrates molybdenum with fast reaction to increasing concentrations in soil. Molybdenum had a positive effect concerning the plant growth (throughout all experimental process, pea plants treated with highest concentrated metal solution reached the largest dimensions. Accumulated molybdenum was directly proportional to increasing concentration of the applied solution to roots, stem, leaves and flowers of the experimental plants; however it resided in flowerpot soil too .In the leguminous roots where the nitroreductase and nitrogenese activity is increased, molybdenum content was much higher compared to the aerial parts of the plant. All the way through molybdenum accumulation in the experimental plants up to high concentrations, other chemical elements revealed lower concentration although within the normal limits, with the exception of phosphorus. These plants were found to assimilate high molybdenum quantities without any detrimental consequences for them since molybdenum accumulation occurred in vacuoles in innocuous chemical forms.

  5. Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Spink, D.

    1990-09-21

    Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{center dot}6PEt{sub 3} and Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} were isolated and characterized. Phosphorus-31 nuclear magnetic resonance, electron paramagnetic resonance, and UV/visible spectra were obtained for each fraction. The completely sulfided cluster, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3}, was prepared similarly and used in various experiments as a possible precursor to Chevrel phase materials of the type Mo{sub 6}S{sub 8}or M{sub n}Mo{sub 6}S{sub 8}. With the goal of removing all of the triethylphosphine ligands, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} was reacted with the transition metal carbonyls molybdenum hexacarbonyl and dicobalt octacarbonyl. Reaction on the molecular sulfide cluster with copper(I) chloride in toluene gave a completely insoluble product. The reaction of Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} with propylene sulfide gave a product whose infrared spectra showed only very weak peaks associated with coordinated triethylphosphine. The elemental analysis of this product fit the formula Mo{sub 6}S{sub 8}{center dot}5SPEt{sub 3}. Reactivity of the outer ligands of the Mo{sub 6}S{sub 8}{center dot}npy and Mo{sub 6}S{sub 8}{center dot}(6{minus}x)PrNH{sub x} clusters were investigated. Crystalline Mo{sub 6}S{sub 8}{center dot}6THT was recovered from the reaction of the n-propylamine derivative with THT. A crystal structure determination was done. 87 refs., 12 fig., 15 tabs.

  6. Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

    Science.gov (United States)

    Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

    2015-08-01

    The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys.

  7. Assessment of density functionals and paucity of non-covalent interactions in aminoylyne complexes of molybdenum and tungsten [(η(5)-C5H5)(CO)2M≡EN(SiMe3)(R)] (E = Si, Ge, Sn, Pb): a dispersion-corrected DFT study.

    Science.gov (United States)

    Pandey, Krishna K; Patidar, Pankaj; Bariya, Pankaj K; Patidar, Sunil K; Vishwakarma, Ravi

    2014-07-14

    Electronic, molecular structure and bonding energy analyses of the metal-aminosilylyne, -aminogermylyne, -aminostannylyne and -aminoplumbylyne complexes [(η(5)-C5H5)(CO)2M[triple bond, length as m-dash]EN(SiMe3)(Ph)] (M = Mo, W) and [(η(5)-C5H5)(CO)2Mo[triple bond, length as m-dash]GeN(SiMe3)(Mes)] have been investigated at DFT, DFT-D3 and DFT-D3(BJ) levels using BP86, PBE, PW91, RPBE, TPSS and M06-L functionals. The performance of metaGGA functionals for the geometries of aminoylyne complexes is better than GGA functionals. Significant dispersion interactions between OH, EC(O) and EH pairs appeared in the dispersion-corrected geometries. The non-covalent distances of these interactions follow the order DFT > DFT-D3(BJ) > DFT-D3. The values of Nalewajski-Mrozek bond order (1.22-1.52) and Pauling bond order (2.23-2.59) of the optimized structures at BP86/TZ2P indicate the presence of multiple bonds between metal and E atoms. The overall electronic charges transfer from transition-metal fragments to ligands. The topological analysis based on QTAIM has been performed to determine the analogy of non-covalent interactions. The strength of M[triple bond, length as m-dash]EN(SiMe3)(R) bonds has been evaluated by energy decomposition analysis. The electrostatic interactions are almost equal to orbital interactions. The M ← E σ-donation is smaller than the M → E π-back donation. Upon going from E = Si to E = Pb, the M-E bond orders decrease as Si > Ge > Sn > Pb, consistent with the observed geometry trends. The M-E uncorrected bond dissociation energies vary with the density functionals as RPBE DFT-D3 dispersion corrections to the BDEs correspond to the BP86 functional, ranging between 5.6-8.1 kcal mol(-1), which are smaller than the DFT-D3(BJ) dispersion corrections (10.1-12.0 kcal mol(-1)). The aryl substituents on nitrogen have an insignificant effect on M-E-N bending. The bending of the M-E-N bond angle has been discussed in terms of Jahn-Teller distortion. The

  8. Hydrogen reduction of molybdenum oxide at room temperature

    Science.gov (United States)

    Borgschulte, Andreas; Sambalova, Olga; Delmelle, Renaud; Jenatsch, Sandra; Hany, Roland; Nüesch, Frank

    2017-01-01

    The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

  9. Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst.

    Science.gov (United States)

    Vyas, Shruti; Ting, Yen-Peng

    2016-10-01

    Spent catalyst bioleaching with Acidithiobacillus ferrooxidans has been widely studied and low Mo leaching has often been reported. This work describes an enhanced extraction of Mo via a two stage sequential process for the bioleaching of hydrodesulphurization spent catalyst containing Molybdenum, Nickel and, Aluminium. In the first stage, two-step bioleaching was performed using Acidithiobacillus ferrooxidans, and achieved 89.4% Ni, 20.9% Mo and 12.7% Al extraction in 15 days. To increase Mo extraction, the bioleached catalyst was subjected to a second stage bioleaching using Escherichia coli, during which 99% of the remaining Mo was extracted in 25 days. This sequential bioleaching strategy selectively extracted Ni in the first stage and Mo in the second stage, and is a more environmentally friendly alternative to sequential chemical leaching with alkaline reagents for improved Mo extraction. Kinetic modelling to establish the rate determining step in both stages of bioleaching showed that in the first stage, Mo extraction was chemical reaction controlled whereas in the subsequent stage, product layer diffusion model provided the best fit.

  10. Thermochemical Analysis of Molybdenum Thin Films on Porous Alumina.

    Science.gov (United States)

    Lee, Kyoungjin; de Lannoy, Charles-François; Liguori, Simona; Wilcox, Jennifer

    2017-01-12

    Molybdenum (Mo) thin films (thickness thin-film composites were stable below 300 °C but had no reactivity toward gases. Mo thin films showed nitrogen incorporation on the surface as well as in the subsurface at 450 °C, as confirmed by X-ray photoelectron spectroscopy. The reactivity toward nitrogen was diminished in the presence of CO2, although no carbon species were detected either on the surface or in the subsurface. The Mo thin films have a very stable native oxide layer, which may further oxidize to higher oxidation states above 500 °C due to the reaction with the porous anodized alumina substrate. The oxidation of Mo thin films was accelerated in the presence of oxidizing gases. At 600 °C in N2, the Mo thin film on anodized alumina was completely oxidized and may also have been volatilized. The results imply that choosing thermally stable and inactive porous supports and operating in nonoxidizing conditions below 500 °C will likely maintain the stability of the Mo composite. This study provides key information about the chemical and structural stability of a Mo thin film on a porous substrate for future membrane applications and offers further insights into the integrity of thin-film composites when exposed to harsh conditions.

  11. Alternative production methods to face global molybdenum-99 supply shortage.

    Science.gov (United States)

    Lyra, Maria; Charalambatou, Paraskevi; Roussou, Eirini; Fytros, Stavros; Baka, Irini

    2011-01-01

    The sleeping giant of molybdenum-99 ((99)Mo) production is grinding to a halt and the world is wondering how this happened. Fewer than 10 reactors in the world are capable of producing radio nuclides for medicine; approximately 50% of the world's supply of raw material comes from National Research Universal (NRU) reactor in Canada. Many of these reactors, like the NRU, are old and aging. No one of these reactors, and probably not even all of them in combination, can replace the production of NRU. As the healthcare industry faces an aging population and the demand for diagnostic services using (99m)Tc continues to rise, the need for a consistent, reliable supply of (99)Mo has become increasingly important, so alternative methods to produce (99)Mo or even directly (99m)Tc had to be considered to avoid a supply shortage in the coming years. This need guides to the production of (99)Mo by replacing the Highly Enriched Uranium (HEU) target in a nuclear reactor with Low Enriched Uranium (LEU) and furthermore to the use of accelerators for manufacturing (99)Mo or for directly producing (99m)Tc.

  12. Assessing the standard Molybdenum projector augmented wave VASP potentials

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, Ann E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Multi-Scale Science

    2014-07-01

    Density Functional Theory (DFT) based Equation of State (EOS) construction is a prominent part of Sandia’s capabilities to support engineering sciences. This capability is based on augmenting experimental data with information gained from computational investigations, especially in those parts of the phase space where experimental data is hard, dangerous, or expensive to obtain. A key part of the success of the Sandia approach is the fundamental science work supporting the computational capability. Not only does this work enhance the capability to perform highly accurate calculations but it also provides crucial insight into the limitations of the computational tools, providing high confidence in the results even where results cannot be, or have not yet been, validated by experimental data. This report concerns the key ingredient of projector augmented-wave (PAW) potentials for use in pseudo-potential computational codes. Using the tools discussed in SAND2012-7389 we assess the standard Vienna Ab-initio Simulation Package (VASP) PAWs for Molybdenum.

  13. Synthesis, Crystal Structure and Electrical Properties of the Molybdenum Oxide

    Directory of Open Access Journals (Sweden)

    Ennajeh Ines

    2013-01-01

    Full Text Available New molybdenum oxide Na1.92Mg2.04Mo3O12 has been synthesized by the solid state method. The title compound crystallizes in the triclinic system (space group P-1. The unit cell parameters are a = 6.9660(7 Å, b = 8.6352(8 Å, c = 10.2501(8 Å, α = 106.938(1°, β = 104.825(1°, γ = 103.206(1°, V = 538.72(9 Å3, and Z = 2. The compound is isotypical to Ag2M2(MoO43 (M = Zn, Mg, Co, Mn. The structure can be described as a three-dimensional anionic mixed framework of MoO4 tetrahedra and pairs of Mg2O10 octahedra sharing common edges. The Na+ ions are disordered and located in the voids forming infinite channels running along the direction [100]. The electrical conductivity investigated from 693 K to 793 K by AC impedance spectroscopy is low ( S cm−1 at 683 K.

  14. EUV nanosecond laser ablation of silicon carbide, tungsten and molybdenum

    Science.gov (United States)

    Frolov, Oleksandr; Kolacek, Karel; Schmidt, Jiri; Straus, Jaroslav; Choukourov, Andrei; Kasuya, Koichi

    2015-09-01

    In this paper we present results of study interaction of nanosecond EUV laser pulses at wavelength of 46.9 nm with silicon carbide (SiC), tungsten (W) and molybdenum (Mo). As a source of laser radiation was used discharge-plasma driver CAPEX (CAPillary EXperiment) based on high current capillary discharge in argon. The laser beam is focused with a spherical Si/Sc multilayer-coated mirror on samples. Experimental study has been performed with 1, 5, 10, 20 and 50 laser pulses ablation of SiC, W and Mo at various fluence values. Firstly, sample surface modification in the nanosecond time scale have been registered by optical microscope. And the secondly, laser beam footprints on the samples have been analyzed by atomic-force microscope (AFM). This work supported by the Czech Science Foundation under Contract GA14-29772S and by the Grant Agency of the Ministry of Education, Youth and Sports of the Czech Republic under Contract LG13029.

  15. Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

    Directory of Open Access Journals (Sweden)

    Pravas Kumar Panigrahi

    2013-01-01

    Full Text Available Synthesis of poorly crystalline, randomly oriented rag-like structures of molybdenum disulfide has been reported starting from aqueous solutions of ammonium molybdate, and thioacetamide in presence of sodium dodecyl sulfate via calcination of the amorphous precipitates, obtained through acidification of the in situ generated intermediate of ammonium tetrathiomolybdate. X-ray photoelectron spectroscopy, UV-visible spectroscopy, and X-ray diffraction of the calcined samples reveal the formation of single-phase MoS2, while the amorphous precipitates have been found to be a mixture of Mo2S5, MoS3, and a trace amount of H2MoS4. Highly folded and disordered layers of rag-like MoS2 have been confirmed through high-resolution transmission electron microscopy. The electrical conductivity for the cold pressed pellet of the MoS2 sample is found to be significantly higher than that of 2H-MoS2 and increases further on annealing.

  16. Microstructure and texture development during recrystallization of rolled molybdenum sheets

    Energy Technology Data Exchange (ETDEWEB)

    Huensche, I.; Oertel, C.G.; Tamm, R.; Skrotzki, W. [Dresden Univ. of Technology, Inst. of Structural Physics (Germany); Knabl, W. [Plansee AG, Technologiezentrum, Reutte/Tyrol (Austria)

    2004-07-01

    Recrystallization is an important tool to adjust the grain size and texture of polycrystalline materials in order to optimize their properties. In the present work recrystallization and the related changes of texture have been studied on rolled molybdenum sheets as a function of temperature and time. The microstructure was investigated by orientation contrast in a scanning electron microscope. The kinetics of recrystallization displayed in a JMAK plot yields avrami coefficients decreasing with temperature from 2.5 to 1.1. The activation energy amounts to 5 eV, which agrees well with the volume self-diffusion coefficient. The textures of the sheet surface and central layer were measured by X-ray diffraction. The rolling texture in the centre of the sheets is characterized by a strong {alpha}-fibre with the rotated cube component {l_brace}100{r_brace}<110> dominating. Besides that, there exists a weak {gamma}-fibre. In contrast, the surface layer is characterized by a weak cube component. During recrystallization changes in texture are insignificant. With long annealing times all texture components tend to degrade. Conclusions regarding the deep-drawability are drawn. (orig.)

  17. Preparation and characterization of DC sputtered molybdenum thin films

    Directory of Open Access Journals (Sweden)

    Abd El-Hady B. Kashyout

    2011-03-01

    Full Text Available Molybdenum (Mo thin films have been deposited on soda-lime glass substrates using a DC magnetron sputtering system. Their electrical resistivity, and their morphological, structural and adhesive properties have been examined with respect to the deposition power, deposition time and substrate temperature. The electrical resistivity of the Mo films could be reduced by increasing any of the above parameters. Within the range of the investigated deposition parameters, the films showed a mono-crystalline nature with a preferred orientation along the (1 1 0 plane. The Mo films adhesion to the soda-lime glass could be improved by increasing the substrate temperature. At a deposition power of 200 W, deposition time of 20 min and substrate temperature of 450 °C, Mo thin film exhibiting mono-crystalline structure with thickness equal to 450 nm and electrical resistivity equal to 1.85 × 10−4 Ω cm was obtained.

  18. DNA origami deposition on native and passivated molybdenum disulfide substrates

    Directory of Open Access Journals (Sweden)

    Xiaoning Zhang

    2014-04-01

    Full Text Available Maintaining the structural fidelity of DNA origami structures on substrates is a prerequisite for the successful fabrication of hybrid DNA origami/semiconductor-based biomedical sensor devices. Molybdenum disulfide (MoS2 is an ideal substrate for such future sensors due to its exceptional electrical, mechanical and structural properties. In this work, we performed the first investigations into the interaction of DNA origami with the MoS2 surface. In contrast to the structure-preserving interaction of DNA origami with mica, another atomically flat surface, it was observed that DNA origami structures rapidly lose their structural integrity upon interaction with MoS2. In a further series of studies, pyrene and 1-pyrenemethylamine, were evaluated as surface modifications which might mitigate this effect. While both species were found to form adsorption layers on MoS2 via physisorption, 1-pyrenemethylamine serves as a better protective agent and preserves the structures for significantly longer times. These findings will be beneficial for the fabrication of future DNA origami/MoS2 hybrid electronic structures.

  19. Iron binary and ternary coatings with molybdenum and tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Yar-Mukhamedova, Gulmira, E-mail: gulmira-alma-ata@mail.ru [Institute Experimental and Theoretical Physics Al-Farabi Kazakh National University, 050038, Al-Farabi av., 71, Almaty (Kazakhstan); Ved, Maryna; Sakhnenko, Nikolay; Karakurkchi, Anna; Yermolenko, Iryna [National Technical University “Kharkov Polytechnic Institute”, Kharkov (Ukraine)

    2016-10-15

    Highlights: • High quality coatings of double Fe-Mo and ternary Fe-Mo-W electrolytic alloys can be produced both in a dc and a pulsed mode. • Application of unipolar pulsed current allows receiving an increased content of the alloying components and their more uniform distribution over the surface. • It is established that Fe-Mo and Fe-Mo-W coatings have an amorphous structure and exhibit improved corrosion resistance and microhardness as compared with the steel substrate due to the inclusion molybdenum and tungsten. - Abstract: Electrodeposition of Fe-Mo-W and Fe-Mo layers from a citrate solution containing iron(III) on steel and iron substrates is compared. The utilization of iron(III) compounds significantly improved the electrolyte stability eliminating side anodic redox reactions. The influence of concentration ratios and electrodeposition mode on quality, chemical composition, and functional properties of the alloys is determined. It has been found that alloys deposited in pulse mode have more uniform surface morphology and chemical composition and contain less impurities. Improvement in physical and mechanical properties as well as corrosion resistance of Fe-Mo and Fe-Mo-W deposits when compared with main alloy forming metals is driven by alloying components chemical passivity as well as by alloys amorphous structure. Indicated deposits can be considered promising materials in surface hardening technologies and repair of worn out items.

  20. "Non-hydrolytic" sol-gel synthesis of molybdenum sulfides

    Science.gov (United States)

    Leidich, Saskia; Buechele, Dominique; Lauenstein, Raphael; Kluenker, Martin; Lind, Cora

    2016-10-01

    Non-hydrolytic sol-gel reactions provide a low temperature solution based synthetic approach to solid-state materials. In this paper, reactions between molybdenum chloride and hexamethyldisilthiane in chloroform were explored, which gave access to both MoS2 and Mo2S3 after heat treatment of as-recovered amorphous samples to 600-1000 °C. Interesting morphologies were obtained for MoS2, ranging from fused spherical particles to well-defined nanoplatelets and nanoflakes. Both 2H- and 3R-MoS2 were observed, which formed thin hexagonal and triangular platelets, respectively. The platelets exhibited thicknesses of 10-30 nm, which corresponds to 15-50 MoS2 layers. No attempts to prevent agglomeration were made, however, well separated platelets were observed for many samples. Heating at 1000 °C led to formation of Mo2S3 for samples that showed well-defined MoS2 at lower temperatures, while less crystalline samples had a tendency to retain the MoS2 structure.

  1. Molybdenum (VI) binded to humic and nitrohumic acid models in aqueous solutions: phthalic, 3- and 4-nitrophthalic acids, catechol and 4-nitrocathecol, part 1

    Energy Technology Data Exchange (ETDEWEB)

    Merce, Ana Lucia R.; Greboge, Cristiane; Mendes, Giovani; Mangrich, Antonio S. [Parana Univ., Curitiba, PR (Brazil). Dept. de Quimica]. E-mail: anamerce@ufpr.br

    2005-02-01

    Many mathematical models have been tested in the literature in the search of how humic acids (HA) from many natural sources complex to metal ions. HA are composed of natural degradation sources of C, N, P and S, bearing hydroxyl and carboxyl aromatic units in their inner structure. The presence of metal ions binded to these basic sites promotes fertility to the soil as well as can hold metal ions to be slowly released as the mineralization of the soil occurs. Nitrohumic substances are a laboratory artifact with higher N content then humic acids with an electron withdrawing group - NO{sub 2}. However they still bear the main HA constituent chemical groups such as salicylate, catecholate and phthalate derivatives, all prone to bind to metal ions depending on the chemical conditions of the environment. This work intended to study the complexing behaviour of some HA models having very different Lewis basic binding sites in the presence of molybdenum (VI) ions, in aqueous systems, with varying pH values using some analytical tools. The formation constants of phthalic acid, 3- and 4-nitrophthalic acids, catechol and 4-nitrocatechol with Mo(VI) as well as the speciation of the complex species according to varying pH values were determined. Potentiometric and cyclic voltammetric titrations were employed to calculate the formation constants and to monitor the formation and decomposition of some complexed species. The results showed that although there is complexation between phthalic derived acids and molybdenum, the speciation favours it only until pH 6.0 at the best. On the other hand, salicylic and catechol derived models showed existence of complexation until basic pH values, allowing a compromising complexation pH range when humic and nitrohumic substances are involved. (author)

  2. Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum

    Science.gov (United States)

    Liu, Rong; Yao, J. H.; Zhang, Q. L.; Yao, M. X.; Collier, Rachel

    2015-12-01

    Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.

  3. Reduction of molybdenum oxide from steelmaking slags by pure liquid iron

    Directory of Open Access Journals (Sweden)

    Gao Y.M.

    2012-01-01

    Full Text Available The effects of reaction temperature, slag basicity and FeO concentration on the reduction of molybdenum oxide from steelmaking slags by pure liquid iron were investigated experimently. The reduction kinetics of molybdenum oxide by liquid iron was analysed. The reaction models were developed based on the condition that diffusion of [Mo] in liquid iron and CaMoO4 in slag is the control steps, respectively. These reaction models were tested using data from a series of experiments. The results indicate that under the present experimental conditions, the temperature and the FeO content, other than slag basicity, have some effects on the reduction of molybdenum oxide from steelmaking slags by pure liquid iron. Both the molybdenum oxide reduction rate and final reduction ratio increase with an increase of temperature and a decrease of FeO content. The diffusion of CaMoO4 in slag which dominated overall reduction process is the only one ratecontrolling step with its apparent activation energy 294 kJ/mol. The reduction of molybdenum oxide used directly as alloy additive can be further enhanced by strong stirring in the converter practice.

  4. Oxidation states of molybdenum in oxide films formed in sulphuric acid and sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo, I.A.; Doff, J.; Baron-Wiechec, A. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Jones, G. [Waters Corporation, Floats Rd, Roundthorn Ind. Est., Manchester M23 9LZ (United Kingdom); Koroleva, E.V. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Skeldon, P., E-mail: p.skeldon@manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2012-07-31

    X-ray photoelectron spectroscopy is used to investigate the oxidation states of molybdenum in thin films formed potentiostatically, over a range of potentials, in either 1 mol dm{sup -3} H{sub 2}SO{sub 4} or 10 mol dm{sup -3} NaOH at 20 Degree-Sign C. Mo 3d spectra suggested that MoO{sub 2} and Mo(OH){sub 2} were the main components of the films, with smaller amounts of MoO{sub 3} and possibly Mo{sub 2}O{sub 5}. O 1s spectra indicated the presence of oxygen as oxide and hydroxide species and as bound water. Ion beam analysis revealed the formation of thin films at all potentials, with significant losses of oxidized molybdenum to the electrolyte. - Highlights: Black-Right-Pointing-Pointer Oxides are formed on molybdenum in sulphuric acid and sodium hydroxide solutions. Black-Right-Pointing-Pointer Molybdenum IV and VI are identified by XPS, with MoO2 species dominating. Black-Right-Pointing-Pointer Thicknesses of films are determined by ion beam analysis for a range of potentials. Black-Right-Pointing-Pointer Films form at low efficiency due to loss of molybdenum species to electrolyte.

  5. Reduction of molybdate to molybdenum blue by Enterobacter sp. strain Dr.Y13.

    Science.gov (United States)

    Shukor, M Y; Rahman, M F; Shamaan, N A; Syed, M A

    2009-09-01

    Extensive use of metals in various industrial applications has caused substantial environmental pollution. Molybdenum-reducing bacteria isolated from soils can be used to remove molybdenum from contaminated environments. In this work we have isolated a local bacterium with the capability to reduce soluble molybdate to the insoluble molybdenum blue. We studied several factors that would optimize molybdate reduction. Electron donor sources such as glucose, sucrose, lactose, maltose and fructose (in decreasing efficiency) supported molybdate reduction after 24 h of incubation with optimum glucose concentration for molybdate reduction at 1.5% (w/v). The optimum pH, phosphate and molybdate concentrations, and temperature for molybdate reduction were pH 6.5, 5.0, 25 to 50 mM and 37 degrees C, respectively. The Mo-blue produced by cellular reduction exhibited a unique absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Metal ions such as chromium, cadmium, copper, silver and mercury caused approximately 73, 71, 81, 77 and 78% inhibition of the molybdenum-reducing activity, respectively. All of the respiratory inhibitors tested namely rotenone, azide, cyanide and antimycin A did not show any inhibition to the molybdenum-reducing activity suggesting components of the electron transport system are not responsible for the reducing activity. The isolate was tentatively identified as Enterobacter sp. strain Dr.Y13 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny.

  6. Reduction of molybdate to molybdenum blue by Klebsiella sp. strain hkeem.

    Science.gov (United States)

    Lim, H K; Syed, M A; Shukor, M Y

    2012-06-01

    A novel molybdate-reducing bacterium, tentatively identified as Klebsiella sp. strain hkeem and based on partial 16s rDNA gene sequencing and phylogenetic analysis, has been isolated. Strain hkeem produced 3 times more molybdenum blue than Serratia sp. strain Dr.Y8; the most potent Mo-reducing bacterium isolated to date. Molybdate was optimally reduced to molybdenum blue using 4.5 mM phosphate, 80 mM molybdate and using 1% (w/v) fructose as a carbon source. Molybdate reduction was optimum at 30 °C and at pH 7.3. The molybdenum blue produced from cellular reduction exhibited absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide, and potassium cyanide did not inhibit the molybdenum-reducing enzyme. Mercury, silver, and copper at 1 ppm inhibited molybdenum blue formation in whole cells of strain hkeem.

  7. Low-temperature irradiation behavior of uranium-molybdenum alloy dispersion fuel

    Science.gov (United States)

    Meyer, M. K.; Hofman, G. L.; Hayes, S. L.; Clark, C. R.; Wiencek, T. C.; Snelgrove, J. L.; Strain, R. V.; Kim, K.-H.

    2002-08-01

    Irradiation tests have been conducted to evaluate the performance of a series of high-density uranium-molybdenum (U-Mo) alloy, aluminum matrix dispersion fuels. Fuel plates incorporating alloys with molybdenum content in the range of 4-10 wt% were tested. Two irradiation test vehicles were used to irradiate low-enrichment fuels to approximately 40 and 70 at.% 235U burnup in the advanced test reactor at fuel temperatures of approximately 65 °C. The fuel particles used to fabricate dispersion specimens for most of the test were produced by generating filings from a cast rod. In general, fuels with molybdenum contents of 6 wt% or more showed stable in-reactor fission gas behavior, exhibiting a distribution of small, stable gas bubbles. Fuel particle swelling was moderate and decreased with increasing alloy content. Fuel particles with a molybdenum content of 4 wt% performed poorly, exhibiting extensive fuel-matrix interaction and the growth of relatively large fission gas bubbles. Fuel particles with 4 or 6 wt% molybdenum reacted more rapidly with the aluminum matrix than those with higher-alloy content. Fuel particles produced by an atomization process were also included in the test to determine the effect of fuel particle morphology and microstructure on fuel performance for the U-10Mo composition. Both of the U-10Mo fuel particle types exhibited good irradiation performance, but showed visible differences in fission gas bubble nucleation and growth behavior.

  8. Controle da podridão parda do pessegueiro com fungicidas e fosfitos avaliados em pré e pós-colheita Control of peach tree brown rot by fungicides and phosphites evaluated during preharvest and postharvest

    Directory of Open Access Journals (Sweden)

    Luciene Martins Moreira

    2009-04-01

    Full Text Available A podridão parda é a doença mais importante para a cultura do pessegueiro, entretanto, no Brasil são escassos os trabalhos realizados a campo visando o seu controle. Objetivou-se, neste trabalho, selecionar fungicidas em laboratório e avaliar a sua eficiência e de fosfitos a campo, para o controle da podridão parda monitorando as fases de desenvolvimento de frutos e pós-colheita, além de avaliar as características qualitativas dos frutos. O experimento de campo foi realizado com seis tratamentos e quatro repetições: três fungicidas pré-selecionados in vitro (iminoctadine tris albesilate, myclobutanil e iprodione, dois fosfitos (CaB e de K e testemunha. Foi avaliada a incidência de infecções latentes de Monilinia fructicola em frutos em desenvolvimento e em frutos maduros após a colheita. Para os frutos em desenvolvimento observou-se maior incidência nas duas últimas coletas. No campo, o iprodione e o iminoctadine mostraram eficiência no controle da doença durante as avaliações. Após três dias no ambiente o iminoctadine foi melhor que os demais tratamentos mantendo a incidência da podridão parda em 1,0% contra 31,4% no tratamento com iprodione e 91,2% na testemunha. O fosfito de CaB não mostrou diferença em relação à testemunha no decorrer das avaliações, mas o fosfito de K, reduziu em 60 e 28% o número de frutos doentes aos três e cinco dias, respectivamente, em relação à testemunha. Quanto aos parâmetros de qualidade, o peso médio dos frutos, o diâmetro e a firmeza da polpa, não mostraram diferenças significativas em relação à testemunha.Brown rot is the most important disease in peach tree cultivation, but field studies with control methods are currently rare in Brazil. One of the objectives of this study was to select fungicides in the laboratory then test them in the field, additionally to phosphites, for the control of the brown rot. The control was performed by observing the fruit development

  9. Phosphite as phosphorus source to grain yield of common bean plants grown in soils under low or adequate phosphate availability Fosfito como fonte de fósforo para produção de grãos em feijoeiro cultivado em solos sob baixa ou adequada disponibilidade de fosfato

    Directory of Open Access Journals (Sweden)

    Fabricio William Ávila

    2012-12-01

    Full Text Available The effects of foliar and soil applied phosphite on grain yield in common bean (Phaseolus vulgaris L. grown in a weathered soil under low and adequate phosphate availability were evaluated. In the first experiment, treatments were composed of a 2 x 7 + 2 factorial scheme, with 2 soil P levels supplied as phosphate (40 e 200 mg P dm-3 soil, 7 soil P levels supplied as phosphite (0-100 mg P dm-3 soil, and 2 additional treatments (without P supply in soil, and all P supplied as phosphite. In the second experiment, treatments were composed of a 2 x 3 x 2 factorial scheme, with 2 soil phosphate levels (40 e 200 mg P dm-3 soil, combined with 3 nutrient sources applied via foliar sprays (potassium phosphite, potassium phosphate, and potassium chloride as a control, and 2 foliar application numbers (single and two application. Additional treatments showed that phosphite is not P source for common bean nutrition. Phosphite supply in soil increased the P content in shoot (at full physiological maturity stage and grains, but at the same time considerably decreased grain yield, regardless of the soil phosphate availability. Foliar sprays of phosphite decreased grain yield in plants grown under low soil phosphate availability, but no effect was observed in plants grown under adequate soil phosphate availability. In general, foliar sprays of phosphate did not satisfactorily improve grain yield of the common bean plants grown under low soil phosphate availability.Os efeitos de fosfito aplicado via solo ou foliar sobre produção de grãos em feijoeiro (Phaseolus vulgaris L., cultivado em um solo intemperizado sob baixa ou adequada disponibilidade de fosfato foram avaliados. No primeiro experimento, o delineamento consistiu de um esquema fatorial 2 x 7 + 2, sendo 2 doses de P fornecidas na forma de fosfato (40 e 200 mg P dm-3 de solo x 7 doses de P no solo fornecidas na forma de fosfito (0-100 mg P dm-3 de solo, mais 2 tratamentos adicionais (sem fornecimento

  10. X-ray Diffraction Study of Molybdenum to 900 GPa

    Science.gov (United States)

    Wang, J.; Coppari, F.; Smith, R.; Eggert, J.; Boehly, T.; Collins, G. W.; Duffy, T. S.

    2013-12-01

    Molybdenum (Mo) is a transition metal that is important as a high-pressure standard. Its equation of state, structure, and melting behavior have been explored extensively in both experimental and theoretical studies. Melting data up to the Mbar pressure region from static compression experiments in the diamond anvil cell [Errandonea et al. 2004] are inconsistent with shock wave sound velocity measurements [Hixson et al., 1989]. There are also conflicting reports as to whether body-centered cubic (BCC) Mo transforms to a face-centered cubic (FCC), hexagonal close packed (HCP) or double hexagonal close packed (DHCP) structure at either high pressure or high pressure and temperature conditions [Belonoshko et al. 2008, Mikhaylushkin et al., 2008 and Cazorla et al., 2008]. Recently, a phase transition from BCC to the DHCP phase at 660 GPa and 0 K was predicted using the particle swam optimization (PSO) method (Wang et al, 2013). Here we report an x-ray diffraction study of dynamically compressed molybdenum. Experiments were conducted using the Omega laser at the Laboratory for Laser Energetics at the University of Rochester. Mo targets were either ramp or shock compressed using a laser drive. In ramp loading, the sample is compressed sufficiently slowly that a shock wave does not form. This results in lower temperatures, keeping the sample in the solid state to higher pressures. X-ray diffraction measurements were performed using quasi-monochromatic x-rays from a highly ionized He-α Cu source and image plate detectors. Upon ramp compression, we found no evidence of phase transition in solid Mo up to 900 GPa. The observed peaks can be assigned to the (110) and (200) or (220) reflections of BCC Mo up to the highest pressure, indicating that Mo does not melt under ramp loading to maximum pressure reached. Under shock loading, we did not observe any evidence for the solid-solid phase transformation around 210 GPa as reported in previous work (Hixson et al, 1989). The BCC

  11. Kinetics and Mechanism of Deoxygenation Reactions over Proton-Form and Molybdenum-Modified Zeolite Catalysts

    Science.gov (United States)

    Bedard, Jeremy William

    The depletion of fossil fuel resources and the environmental consequences of their use have dictated the development of new sources of energy that are both sustainable and economical. Biomass has emerged as a renewable carbon feedstock that can be used to produce chemicals and fuels traditionally obtained from petroleum. The oxygen content of biomass prohibits its use without modification because oxygenated hydrocarbons are non-volatile and have lower energy content. Chemical processes that eliminate oxygen and keep the carbon backbone intact are required for the development of biomass as a viable chemical feedstock. This dissertation reports on the kinetic and mechanistic studies conducted on high and low temperature catalytic processes for deoxygenation of biomass precursors to produce high-value chemicals and fuels. Low temperature, steady state reaction studies of acetic acid and ethanol were used to identify co-adsorbed acetic acid/ethanol dimers as surface intermediates within specific elementary steps involved in the esterification of acetic acid with ethanol on zeolites. A reaction mechanism involving two dominating surface species, an inactive ethanol dimeric species adsorbed on Bronsted sites inhibiting ester formation and a co-adsorbed complex of acetic acid and ethanol on the active site reacting to produce ethyl acetate, is shown to describe the reaction rate as a function of temperature (323 -- 383 K), acetic acid (0.5 -- 6.0 kPa), and ethanol (5.0 -- 13.0 kPa) partial pressure on proton-form BEA, FER, MFI, and MOR zeolites. Measured differences in rates as a function of zeolite structure and the rigorous interpretation of these differences in terms of esterification rate and equilibrium constants is presented to show that the intrinsic rate constant for the activation of the co-adsorbed complex increases in the order FER carbon dioxide with methane (CH3COOH/CH4 = 0.04-0.10, HCOOH/CH 4 = 0.01-0.03, CO2/CH4 = 0.01-0.03) on Mo/H-ZSM-5 formulations at

  12. Molybdenum Storage in Cyanobacteria: "Mopping" Up Excess Mo

    Science.gov (United States)

    Glass, J. B.; Wolfe-Simon, F.; Anbar, A. D.

    2008-12-01

    The heavy metal molybdenum (Mo) plays an essential role in the nitrogen (N) cycle. In order to acquire N from the environment, microorganisms utilize Mo-containing enzymes such as nitrogenase (for N2 fixation) and nitrate reductase (for NO3- assimilation). N2-fixing cyanobacteria likely played an important role in both marine and terrestrial N cycling throughout Earth history. Low Mo levels in Precambrian oceans may have necessitated evolution of cyanobacterial Mo-storage ("Mop") proteins. If so, mop genes were likely lost in marine cyanobacteria after the rise of Mo (to approximately 100 nanomolar (nM) 600 Ma (Scott et al., 2008)). The distribution of mop genes in N2-fixing cyanobacteria supports this hypothesis; freshwater species contain this gene whereas marine species lack it. To assess the importance of Mo-storage in modern environments we are integrating laboratory and field investigations. In the lab, we grew N2-fixing freshwater cyanobacteria possessing the mop gene at high Mo levels (1500 nM) to assess whether excess Mo is accumulated Extremely high intracellular accumulation of Mo, much higher than could be accounted for by nitrogenase requirements alone, was observed. Investigation of mop gene expression and protein localization in Mo-replete and deplete conditions is underway. In the field, we are isolating indigenous cyanobacteria and cloning mop genes from Castle Lake, California. This field locale is of particular interest because previous studies show that periphyton consortia in this lake assimilate large quantities of N, even though Mo concentrations are <5 nM. This adaptation to low Mo may be aided by intracellular Mo storage.

  13. Aqueous corrosion behavior of uranium-molybdenum alloys

    Science.gov (United States)

    Gardner, Levi D.

    Nuclear fuel characterization requires understanding of the various conditions to which materials are exposed in-reactor. One of these important conditions is corrosion, particularly that of fuel constituents. Therefore, corrosion behavior is of special interest and an essential part of nuclear materials characterization efforts. In support of the Office of Material Management and Minimization's Reactor Conversion Program, monolithic uranium-10 wt% molybdenum alloy (U-Mo) is being investigated as a low enriched uranium alternative to highly enriched uranium dispersion fuel currently used in domestic high performance research reactors. The aqueous corrosion behavior of U-Mo is being examined at Pacific Northwest National Laboratory (PNNL) as part of U-Mo fuel fabrication capability activity. No prior study adequately represents this behavior given the current state of alloy composition and thermomechanical processing methods, and research reactor water chemistry. Two main measurement techniques were employed to evaluate U-Mo corrosion behavior. Low-temperature corrosion rate values were determined by means of U-Mo immersion testing and subsequent mass-loss measurements. The electrochemical behavior of each processing condition was also qualitatively examined using the techniques of corrosion potential and anodic potentiodynamic polarization. Scanning electron microscopy (SEM) and optical metallography (OM) imagery and hardness measurements provided supplemental corrosion analysis in an effort to relate material corrosion behavior to processing. The processing effects investigated as part of this were those of homogenization heat treatment (employed to mitigate the effects of coring in castings) and sub-eutectoid heat treatment, meant to represent additional steps in fabrication (such as hot isostatic pressing) performed at similar temperatures. Immersion mass loss measurements and electrochemical results both showed very little appreciable difference between

  14. First principles investigation of copper and silver intercalated molybdenum disulfide

    Science.gov (United States)

    Guzman, D. M.; Onofrio, N.; Strachan, A.

    2017-02-01

    We characterize the energetics and atomic structures involved in the intercalation of copper and silver into the van der Waals gap of molybdenum disulfide as well as the resulting ionic and electronic transport properties using first-principles density functional theory. The intercalation energy of systems with formula (Cu,Ag)xMoS2 decreases with ion concentration and ranges from 1.2 to 0.8 eV for Cu; Ag exhibits a stronger concentration dependence from 2.2 eV for x = 0.014 to 0.75 eV for x = 1 (using the fcc metal as a reference). Partial atomic charge analysis indicates that approximately half an electron is transferred per metallic ion in the case of Cu at low concentrations and the ionicity decreases only slightly with concentration. In contrast, while Ag is only slightly less ionic than Cu for low concentrations, charge transfer reduces significantly to approximately 0.1 e for x = 1. This difference in ionicity between Cu and Ag correlates with their intercalation energies. Importantly, the predicted values indicate the possibility of electrochemical intercalation of both Cu and Ag into MoS2 and the calculated activation energies associated with ionic transport within the gaps, 0.32 eV for Cu and 0.38 eV for Ag, indicate these materials to be good ionic conductors. Analysis of the electronic structure shows that charge transfer leads to a shift of the Fermi energy into the conduction band resulting in a semiconductor-to-metal transition. Electron transport calculations based on non-equilibrium Green's function show that the low-bias conductance increases with metal concentration and is comparable in the horizontal and vertical transport directions. These properties make metal intercalated transition metal di-chalcogenides potential candidates for several applications including electrochemical metallization cells and contacts in electronics based on 2D materials.

  15. Ergonomic study of an operator's work of a molybdenum plant.

    Science.gov (United States)

    Oñate, Esteban; Meyer, Felipe

    2012-01-01

    This study was part of an ergonomic program which is being carried out through an agreement between the University of Concepción and a Chilean private mining company. The purpose of this case study was to identify working conditions in which the physical and mental workload could be over the capabilities of the operator. He was responsible for loading trucks with sacks of molybdenum and for downloading reagents and handles them. The methods employed in this study included electronic records, interviews, surveys, review of the company standards, a time study and physical and mental workload analysis. Results showed that 84% of the time the operator was carrying out principal and secondary activities and no break periods were detected. It was found that the pace of work and the shift system generated unfavorable conditions by imbalance in the workload on the different days of the week. In the light of the results recommendations were made for a number of ergonomic changes. Most of them were accepted by the company. The most important achievement was a change in the shift system. The overload of the operator was due to the fact that he was in a shift working 5 days and resting on weekends. The imbalance was mainly because the work of the week end was accumulated for Monday. As a result of the study, the company contracted a second worker for this job and adopted a 7x7 shift system, meaning that they work seven days and rest seven days. An evaluation carried out two month after adopting the new shift revealed that changes were well accepted by the worker.

  16. The in vitro toxicity of cobalt-chrome-molybdenum alloy and its constituent metals.

    Science.gov (United States)

    Evans, E J; Thomas, I T

    1986-01-01

    Cobalt-chrome-molybdenum alloys are widely used in orthopaedic implants. Although they are relatively well tolerated, complications (including loosening and tissue necrosis) still occur and sometimes appear to be due to incomplete biocompatibility of the alloy. To investigate the local effect of the alloy on cells derived from the musculo-skeletal system, primary lines of fibroblastic cells from newborn rats were exposed to powders of cobalt-chrome-molybdenum alloy and its main constituents cobalt, chromium nickel and molybdenum. The toxicity of the metals was determined by counts of total cell number and of abnormal cells at intervals from 2 to 12 d. The alloy was much less toxic than cobalt or nickel and the pattern of toxicity was different for each metal. The results emphasize the difficulty of devising a single tissue culture test of toxicity which will measure the toxicity of any potential implant material.

  17. Progressive dissolution of molybdenum foils in liquid uranium at 1160/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Kuznietz, M.; Cotler, C.

    1988-12-01

    Immersion experiments have been performed to investigate the progressive dissolution of 0.3-mm-thick foils of molybdenum metal in liquid uranium at 1160/sup 0/C, for immersion times of 3, 6, 10, and 60 min, and 20 h, in a zirconia crucible. The original foils, as-received and heat-treated at 1160/sup 0/C, and the uranium-reacted foils have been studied microscopically (SEM-EDAX) and the internal morphology has been determined. The flow lines in as-received molybdenum disappear under heat-treatment, while the undistinguishable grains recrystallize upon heating into grains with average size of 20 m, persisting in samples immersed in liquid uranium. The recrystallization is not uranium-assisted, as uranium does not penetrate into intergranular regions. After incubation time of 3-4 min, outer molybdenum grains dissolve in liquid uranium, thereby reducing the foil thickness progressively. Full dissolution occurs for about 15-min immersion.

  18. Effect of electron-phonon scattering anisotropy on the Hall effect in molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Cherepanov, V.I.; Startsev, V.E.; Volkenshtein, N.V.

    1979-10-01

    The Hall effect is studied in the temperature interval 2--150 K in monocrystalline molybdenum with resistance ratio rho/sub 273.2//rho/sub 4.2/ =32000. For T<80 /sup 0/K the Hall coefficient is anisotropic and has a nonmonotonic temperature dependence. An extremum in R/sub H/(T) is observed at hydrogen temperatures and is sensitive to the magnitude of the magnetic field. The observed behavior of R/sub H/(T) is explained by the Fermi surface geometry of molybdenum and by the influence of the electron-phonon scattering anisotropy. The interpretation of the experimental data is supported by a comparison of the temperature dependences of the Hall coefficient for molybdenum and tungsten.

  19. Comparison of Tungsten and Molybdenum Based Emitters for Advanced Thermionic Space Nuclear Reactors

    Science.gov (United States)

    Lee, Hsing H.; Dickinson, Jeffrey W.; Klein, Andrew C.; Lamp, Thomas R.

    1994-07-01

    Variations to the Advanced Thermionic Initiative thermionic fuel element are analyzed. Analysis included neutronic modeling with MCNP for criticality determination and thermal power distribution, and thermionic performance modeling with TFEHX. Changes to the original ATI configuration include the addition of W-HfC wire to the emitter for high temperature creep resistance improvement and substitution of molybdenum for the tungsten base material. Results from MCNP showed that all the tungsten used in the coating and base material must be 100% W-184 to obtain criticality. The presence of molybdenum in the emitter base affects the neutronic performance of the TFE by increasing the emitter neutron absorption cross section. Due to the reduced thermal conductivity for the molybdenum based emitter, a higher temperature is obtained resulting in a greater electrical power production. The thermal conductivity and resistivity of the composite emitter region were derived for the W-Mo composite and used in TFEHX.

  20. The Extreme Overabundance of Molybdenum in Two Metal-Poor Stars

    CERN Document Server

    Peterson, Ruth C

    2011-01-01

    We report determinations of the molybdenum abundances in five mildly to extremely metal-poor turnoff stars using five Mo II lines near 2000A. In two of the stars, the abundance of molybdenum is found to be extremely enhanced, as high or higher than the neighboring even-Z elements ruthenium and zirconium. Of the several nucleosynthesis scenarios envisioned for the production of nuclei in this mass range in the oldest stars, a high-entropy wind (HEW) acting in a core-collapse supernova seems uniquely capable of the twin aspects of a high molybdenum overproduction confined to a narrow mass range. Whatever the details of the nucleosynthesis mechanism, however, this unusual excess suggests that very few individual nucleosynthesis events were responsible for the synthesis of the light trans-Fe heavy elements in these cases, an unexpected result given that both are only moderately metal-poor.

  1. A redox-assisted molecular assembly of molybdenum oxide amine composite nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Luo Haiyan [Institute of New Energy Technology and Nano-Materials, Fuzhou University, Fuzhou, Fujian 350002 (China); Wei Mingdeng, E-mail: wei-mingdeng@fzu.edu.cn [Institute of New Energy Technology and Nano-Materials, Fuzhou University, Fuzhou, Fujian 350002 (China); National Engineering Research Center for Chemical Fertilizer Catalyst, Fuzhou University, Fuzhou, Fujian 350002 (China); Wei Kemei [National Engineering Research Center for Chemical Fertilizer Catalyst, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2011-01-21

    Research highlights: > Nanobelts of molybdenum oxide amine were first synthesized via a redox-assisted molecular assembly route. > These nanobelts are highly crystalline with a several tens of micrometers in length and 20-30 nm in thickness. - Abstract: In this paper, the nanobelts of molybdenum oxide amine composite were successfully synthesized via a redox-assisted molecular assembly route under the hydrothermal conditions. The synthesized nanobelts were characterized by XRD, SEM, TEM, TG and FT-IR measurements. The thickness of nanobelts is found to be ca. 20-30 nm and their lengths are up to several tens of micrometers. Based on a series of the experimental results, a possible model, redox-intercalation-exfoliation, was suggested for the formation of nanobelts of molybdenum oxide amine composite.

  2. Molybdenum and tungsten oxygen transferases--and functional diversity within a common active site motif.

    Science.gov (United States)

    Pushie, M Jake; Cotelesage, Julien J; George, Graham N

    2014-01-01

    Molybdenum and tungsten are the only second and third-row transition elements with a known function in living organisms. The molybdenum and tungsten enzymes show common structural features, with the metal being bound by a pyranopterin-dithiolene cofactor called molybdopterin. They catalyze a variety of oxygen transferase reactions coupled with two-electron redox chemistry in which the metal cycles between the +6 and +4 oxidation states usually with water, either product or substrate, providing the oxygen. The functional roles filled by the molybdenum and tungsten enzymes are diverse; for example, they play essential roles in microbial respiration, in the uptake of nitrogen in green plants, and in human health. Together, the enzymes form a superfamily which is among the most prevalent known, being found in all kingdoms of life. This review discusses what is known of the active site structures and the mechanisms, together with some recent insights into the evolution of these important enzyme systems.

  3. Investigations on bactericidal properties of molybdenum-tungsten oxides combinatorial thin film material libraries.

    Science.gov (United States)

    Mardare, Cezarina Cela; Hassel, Achim Walter

    2014-11-10

    A combinatorial thin film material library from the molybdenum-tungsten refractory metals oxides system was prepared by thermal coevaporation, and its structural and morphological properties were investigated after a multiple step heat treatment. A mixture of crystalline and amorphous oxides and suboxides was obtained, as well as surface structuring caused by the enrichment of molybdenum oxides in large grains. It was found that the oxide phases and the surface morphology change as a function of the compositional gradient. Tests of the library antimicrobial activity against E. coli were performed and the antimicrobial activity was proven in some defined compositional ranges. A mechanism for explaining the observed activity is proposed, involving a collective contribution from (i) increased local acidity due to the enrichment in large grains of molybdenum oxides with different stoichiometry and (ii) the release of free radicals from the W18O49 phase under visible light.

  4. The bioconcentration and bioaccumulation factors for molybdenum in the aquatic environment from natural environmental concentrations up to the toxicity boundary

    Energy Technology Data Exchange (ETDEWEB)

    Regoli, Lidia, E-mail: dagobert.heijerick@arche-consulting.be [IMOA, 4 Heathfield Terrace, Chiswick, London, W4 4JE (United Kingdom); Van Tilborg, Wim [VTBC Beekhuizenseweg 46, 6881Al Plaats, Velp (Netherlands); Heijerick, Dagobert [ARCHE Consulting, Stapelplein 70 box 104, 9000 Gent (Belgium); Stubblefield, William [Oregon State University, Department of Environmental and Molecular Toxicology, 421 Weniger Hall, Corvallis, OR 97331 (United States); Carey, Sandra [IMOA, 4 Heathfield Terrace, Chiswick, London, W4 4JE (United Kingdom)

    2012-10-01

    In a regulatory context, bioaccumulation or bioconcentration factors are used for considering secondary poisoning potential and assessing risks to human health via the food chain. In this paper, literature data on the bioaccumulation of molybdenum in the aquatic organisms are reviewed and assessed for relevance and reliability. The data available in the literature were generated at exposure concentrations below those recommended in the REACH registration dossiers for molybdenum compounds i.e. PNEC{sub freshwater} 12.7 mg Mo/L. To address possible environmental concerns at regulatorily-relevant molybdenum concentrations, both a field study and a laboratory study were conducted. In the field study, whole body and organ-specific molybdenum levels were evaluated in fish (eel, stickleback, perch, carp bream, roach) held in the discharge water collector tanks of a molybdenum processing plant, containing a mean measured molybdenum level of 1.03 mg Mo/L. In the laboratory study, rainbow trout were exposed to two different nominal molybdenum levels (1.0 and 12.7 mg Mo/L), for 60 days followed by a 60-day depuration period. Whole body concentrations in rainbow trout during the exposure period were between < 0.20 and 0.53 mg Mo/L. Muscle tissue molybdenum concentrations in fish taken from both experiments remained below 0.2 mg/kg dry wt. These studies show an inverse relationship between exposure concentration and bioconcentration or bioaccumulation factor for molybdenum. In aquatic organisms, and in fish in particular, internal molybdenum concentrations are maintained in the presence of variation in external molybdenum concentrations. These observations must be considered when evaluating potential risks associated with the bioconcentration and/or bioaccumulation of molybdenum in the aquatic environment. -- Highlights: Black-Right-Pointing-Pointer Addressing environmental concerns at regulatory-relevant molybdenum concentrations. Black-Right-Pointing-Pointer Inverse

  5. A model for recovery of scrap monolithic uranium molybdenum fuel by electrorefining

    Science.gov (United States)

    Van Kleeck, Melissa A.

    The goal of the Reduced Enrichment for Research and Test Reactors program (RERTR) is toreduce enrichment at research and test reactors, thereby decreasing proliferation risk at these facilities. A new fuel to accomplish this goal is being manufactured experimentally at the Y12 National Security Complex. This new fuel will require its own waste management procedure,namely for the recovery of scrap from its manufacture. The new fuel is a monolithic uraniummolybdenum alloy clad in zirconium. Feasibility tests were conducted in the Planar Electrode Electrorefiner using scrap U-8Mo fuel alloy. These tests proved that a uranium product could be recovered free of molybdenum from this scrap fuel by electrorefining. Tests were also conducted using U-10Mo Zr clad fuel, which confirmed that product could be recovered from a clad version of this scrap fuel at an engineering scale, though analytical results are pending for the behavior of Zr in the electrorefiner. A model was constructed for the simulation of electrorefining the scrap material produced in the manufacture of this fuel. The model was implemented on two platforms, Microsoft Excel and MatLab. Correlations, used in the model, were developed experimentally, describing area specific resistance behavior at each electrode. Experiments validating the model were conducted using scrap of U-10Mo Zr clad fuel in the Planar Electrode Electrorefiner. The results of model simulations on both platforms were compared to experimental results for the same fuel, salt and electrorefiner compositions and dimensions for two trials. In general, the model demonstrated behavior similar to experimental data but additional refinements are needed to improve its accuracy. These refinements consist of a function for surface area at anode and cathode based on charge passed. Several approximations were made in the model concerning areas of electrodes which should be replaced by a more accurate function describing these areas.

  6. Multiple Coordination of CO on Molybdenum Nanoparticles: Evidence for Intermediate Mox(CO)y Species by XPS and UPS.

    Science.gov (United States)

    Jiang, Zhiquan; Huang, Weixin; Zhang, Zhen; Zhao, Hong; Tan, Dali; Bao, Xinhe

    2006-12-28

    CO chemisorption on the metallic molybdenum nanoparticles supported on the thin alumina film was investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). A binary compound of molybdenum and CO is found to be formed on the surface upon CO dose, accompanied with a positive binding energy shift of the Mo 3d doublet and a localized Mo 4d valence band. A loose packing of the metallic molybdenum favors the formation of this intermediate Mox(CO)y species. The formation of the Mox(CO)y species implies that the property of the metallic molybdenum nanoparticles on the thin alumina film is much different from that of the bulk molybdenum, indicating a significant nanometer size effect.

  7. Influence of ambient gases on the dc saturated breakdown field of molybdenum, tungsten, and copper during intense breakdown conditioning

    CERN Document Server

    Ramsvik, T; Reginelli, A; Taborelli, M

    2007-01-01

    A comprehensive investigation of the effect of Ar, H2, air, and CO on the saturated breakdown field (Esat) of molybdenum, tungsten, and copper has been performed at intensive breakdown conditioning. A significant decrease in Esat is observed for molybdenum and tungsten when exposed to air. Specifically, at air pressures of ∼10-5   mbar, the decrease in Esat is found to be up to 50% and ∼30% compared to UHV conditions for molybdenum and tungsten, respectively. In addition, a ∼30% decrease is found when molybdenum is conditioned with a ∼10-5   mbar CO pressure. Surface analysis measurements and breakdown conditioning in O2 ambience imply that the origin of the decrease in Esat is closely linked to oxide formation on the electrode surfaces. Ex situ heat treatment of molybdenum is shown to improve the breakdown characteristics drastically.

  8. Low resistivity molybdenum thin film towards the back contact of dye-sensitized solar cell

    Indian Academy of Sciences (India)

    Vuong Son; Tran Thi Ha; Luong T Thu Thuy; Nguyen Ngoc Ha; Nguyen Duc Chien; Mai Anh Tuan

    2015-12-01

    This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150Wat 18 sccm flow rate of Ar. At such sputtering parameters, the Mo film can reach the lowest resistivity of 1.28E−6 cm at 400 nm thick. And the reflection of Mo membrane was 82%. This value is considered as a very good result for preparation of the back contact of DSSC.

  9. Investigation of welding and brazing of molybdenum and TZM alloy tubes

    Science.gov (United States)

    Lundblad, Wayne E.

    1991-01-01

    This effort involved investigating the welding and brazing techniques of molybdenum tubes to be used as cartridges in the crystal growth cartridge. Information is given in the form of charts and photomicrographs. It was found that the recrystallization temperature of molybdenum can be increased by alloying it with 0.5 percent titanium and 0.1 percent zirconium. Recrystallization temperatures for this alloy, known as TZM, become significant around 2500 F. A series of microhardness tests were run on samples of virgin and heat soaked TZM. The test results are given in tabular form. It was concluded that powder metallurgy TZM may be an acceptable cartridge material.

  10. Investigation of top-emitting OLEDs using molybdenum oxide as anode buffer layer

    Institute of Scientific and Technical Information of China (English)

    LIN Hui; YU Jun-sheng; ZHANG Wei

    2012-01-01

    A high-effective bottom anode is essential for high-performance top-emitting organic light-emitting devices (OLEDs).In this paper,Ag-based top-emitting OLEDs are investigated.Ag has the highest reflectivity for visible light among all metals,yet its hole-injection properties are not ideal for anodes of top-emitting OLED.The performance of the devices is significantly improved using the molybdenum oxide as anode buffer layer at the surface of Ag.By introducing the molybdenum oxide,the hole injection from Ag anodes into top-emitting OLED is largely enhanced with rather high reflectivity retained.

  11. Nanoscal design of molybdenum sulfides for more efficient electro- and photoelectrocatalytic hydrogen evolution

    DEFF Research Database (Denmark)

    Laursen, Anders Bo

    . The electrochemical oxidation behavior of MoSx was investigated compared to that of MoS2, and MoS3. It was found that the MoSx demonstrated a unique oxidation behavior indicating that the active sites were not MoS2 or MoS3-like - further experiments are needed to clarify the relation between oxidation behavior and H2...... of active molybdenum sulfide based H2 evolution catalysts. This demonstrated the potential of molybdenum sulfides as electro- and photoelectrochemical catalysts for the H2 evolution reaction....

  12. Formation and Oxidation of Hydrogen Molybdenum Bronze on platinum electrode in sulfuric acid solution

    Institute of Scientific and Technical Information of China (English)

    Jin LU; Jun Hua DU; Wei Shan Li; Jia Mo FU

    2004-01-01

    Hydrogen molybdenum bronze (HxMoO3) can be electrodeposited on platinum and oxidized in two steps to the hydrogen molybdenum bronze with less amount of hydrogen HyMoO3 (y

  13. Nuclear emulsion with molybdenum filling for observation of {beta}{beta} decay

    Energy Technology Data Exchange (ETDEWEB)

    Ashitkov, V.D. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Bagulya, A.V. [Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Barabash, A.S., E-mail: barabash@itep.r [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Bradnova, V.Ya. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Chernyavsky, M.M. [Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Konovalov, S.I. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Okat' eva, N.M.; Orlova, G.I.; Polukhina, N.G. [Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Pozharova, E.A.; Smirnitsky, V.A. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Starkov, N.I.; Vladimirov, M.S. [Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Umatov, V.I. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation)

    2010-09-21

    The usage of nuclear emulsion with molybdenum powder filling ({approx}5% by weight of dry emulsion) for observation of {beta}{beta} decay is shown to be possible. Estimates for 1 kg of {sup 100}Mo with zero background give the sensitivity for the 0{nu}{beta}{beta} decay of {sup 100}Mo at the level of {approx}1.5x10{sup 24}yr for 1 yr of measurement. Promising elements for the double beta decay search, besides molybdenum ({sup 100}Mo), are also {sup 82}Se, {sup 150}Nd, {sup 96}Zr, {sup 130}Te, {sup 116}Cd, and {sup 48}Ca.

  14. Spectrographic analysis of uranium-molybdenum alloys; Analisis espectrografico de aleaciones uranio-molibdeno

    Energy Technology Data Exchange (ETDEWEB)

    Roca, M.

    1967-07-01

    A spectrographic method of analysis has been developed for uranium-molybdenum alloys containing up to 10 % Mo. The carrier distillation technique, with gallium oxide and graphite as carriers, is used for the semiquantitative determination of Al, Cr, Fe, Ni and Si, involving the conversion of the samples into oxides. As a consequence of the study of the influence of the molybdenum on the line intensities, it is useful to prepare only one set of standards with 0,6 % MoO{sub 3}. Total burning excitation is used for calcium, employing two sets of standards with 0,6 and 7.5 MoO{sub 3}. (Author) 5 refs.

  15. 22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

    Energy Technology Data Exchange (ETDEWEB)

    Geissbühler, Jonas, E-mail: jonas.geissbuehler@epfl.ch; Werner, Jérémie; Martin de Nicolas, Silvia; Hessler-Wyser, Aïcha; Tomasi, Andrea; Niesen, Bjoern; De Wolf, Stefaan [Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, CH-2000 Neuchâtel (Switzerland); Barraud, Loris; Despeisse, Matthieu; Nicolay, Sylvain [CSEM PV-Center, Jaquet-Droz 1, CH-2000 Neuchâtel (Switzerland); Ballif, Christophe [Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, CH-2000 Neuchâtel (Switzerland); CSEM PV-Center, Jaquet-Droz 1, CH-2000 Neuchâtel (Switzerland)

    2015-08-24

    Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with molybdenum oxide films. In this article, we evidence that annealing above 130 °C—often needed for the curing of printed metal contacts—detrimentally impacts hole collection of such devices. We circumvent this issue by using electrodeposited copper front metallization and demonstrate a silicon heterojunction solar cell with molybdenum oxide hole collector, featuring a fill factor value higher than 80% and certified energy conversion efficiency of 22.5%.

  16. Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Barriga Arceo, L. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico) and ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Orozco, E. [Instituto de Fisica UNAM, Apdo Postal 20-364, C.P. 01000 D.F. Mexico (Mexico)]. E-mail: eorozco@fisica.unam.mx; Mendoza-Leon, H. [ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Palacios Gonzalez, E. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: epalacio@imp.mx; Leyte Guerrero, F. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: fleyte@imp.mx; Garibay Febles, V. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: vgaribay@imp.mx

    2007-05-31

    Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 {sup o}C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 {mu}m in length were obtained after heating at 800 {sup o}C, by means of this process.

  17. Molybdenum-99 production from reactor irradiation of molybdenum targets: a viable strategy for enhanced availability of technetium-99m.

    Science.gov (United States)

    Pillai, M R A; Knapp, F F Russ

    2012-08-01

    Fission-produced 99Mo (F 99Mo) is traditionally used for fabrication of 99Mo/99mTc alumina-based column generators. In this paper, several emerging strategies are discussed which are being pursued or have been suggested to overcome the continuing shortages of F 99Mo. In addition to the hopeful eventual success of these proposed new 99Mo and 99mTc production technologies, an additional attractive strategy is the alternative production and use of low specific activity (LSA) 99Mo. This strategy avoids fission and is accomplished by direct activation of molybdenum targets in nuclear reactors, which would preclude sole continued reliance on F 99Mo. The principal focus of this paper is a detailed discussion on the advantages and strategies for enhanced production of LSA 99Mo using an international network of research reactors. Several effective strategies are discussed to obtain 99mTc from LSA 99Mo as well as more efficient use of the alumina-based generator system. The delayed time period between 99Mo production and traditional 99Mo/99mTc alumina column generator manufacture and distribution to user sites results in the loss of more than 50% of 99Mo activity. Another strategy is a paradigm shift in the use of 99Mo by recovering clinical-grade 99mTc from 99Mo solution as an alternative to use of 99Mo/99mTc column generators, thereby avoiding substantial decreased availability of 99Mo from radioactive decay. Implementation of the suggested strategies would be expected to increase availability of 99mTc to the clinical user community by several fold. Additional important advantages for the use of LSA 99Mo include eliminating the need for fission product waste management and precluding proliferation concerns by phasing out the need for high (HEU)- and low (LEU)-enriched uranium targets required for F 99Mo production.

  18. Removing Molybdenum with the Microalgae Extracted from the Wastewater in Semiconductor Plants

    Science.gov (United States)

    Chiu, Yi-Chuan

    2017-04-01

    It has been well recognized that algae biomass can treat highly contaminated water in an effective way. Algae can grows in the natural environment without any care and can be efficiently cultivated. Both of living algae and dry algae biomass have been tested to absorb many kinds of toxic pollutants, because there are multiple functional groups on the algae surface capable of binding molybdenum. Therefore, algae become a good choice for the treatment of molybdenum in contaminated waters. In addition, in Taiwan, semiconductor industry is highly developed in the recent three decades. Subsequently, it is believed that some pollutants, such as molybdenum in this study, have become a threat to the surface water, groundwater and even the whole environment. In the previous studies, molybdenum is a well-known essential nutrient for the algae; therefore, the potential to remove molybdenum with algae from the wastewater is worth to be evaluated. The algae species, Chloroidium saccharophilum, was extracted from the wastewater in semiconductor plants for the study of removing molybdenum. A few sorption experiments have been conducted for evaluating the efficiency of removing molybdenum under different values of pH and molybdenum concentration. The absorption of Chloroidium saccharophilum can reach equilibrium in short times, which are 60 and 120 mins for molybdenum concentrations of 600 and 1200 ppb, respectively. The sorption experiments would accept the duration of 120 mins as the contact time and were performed at pH values of 6, 4 and 2 with different concentrations of molybdenum diluted by deionized water. The experiment data confirms that the isotherm has an excellent agreement on Langmuir adsorption model with the correlation coefficients (r2) of > 0.97. It demonstrates that the adsorption capacity (qmax) has an inverse relationship with pH value, which are 826, 2564 and 4761 mgkg-1 for pH 6, 4 and 2, respectively, while those of net enthalpy of adsorption (KL) are 3

  19. RESEARCH PROGRESS FOR THE RECYCLING OF RENEWABLE MOLYBDENUM RESOURCE%可再生钼资源回收研究进展

    Institute of Scientific and Technical Information of China (English)

    张亨

    2014-01-01

    Renewable molybdenum resources include low grade molybdenum ,waste catalyst ,waste molybdenum powder ,molybdenum metal products processing leftovers ,ammonium molybdate and sodium molybdate production waste water and waste residue.Research progress for the recycling of renewable molybdenum resources were re-viewed.%可再生钼资源包括低品位钼矿、废催化剂、废钼粉、钼金属制品生产下脚料、钼酸铵和钼酸钠生产废渣废水等。本文对可再生钼资源的回收利用研究进行了综述。

  20. Heavy metals mobility associated with the molybdenum mining-concentration complex in the Buryatia Republic, Germany.

    Science.gov (United States)

    Sarapulova, Angelina; Dampilova, Bayarma V; Bardamova, Irina; Doroshkevich, Svetlana G; Smirnova, Olga

    2017-04-01

    Mining of Dzhida ore deposits in Russia has caused the formation of a large tailings dam with technogenic sands and contamination of nearby district soils. Geochemical fractions of technogenic sands were divided by a sequential extraction procedure. The sampling points with maximum concentration of Pb, Cu, and Zn were selected for investigation of heavy metal mobility. Two previously described methods of heavy metal fractionation using selective extraction were applied: a procedure developed by the Community Bureau of Reference of the Commission of the European Communities (BCR procedure) and Tessier's fractionation scheme. Despite some differences in Pb extractions, the two procedures describe equally well the distribution of heavy metals on geochemical fractions. BCR procedure was chosen as a fast method of heavy metal mobile form estimation. For considered mining object, it is revealed that there are different characters of heavy metal mobility sequence in the soils Zn > Cu > Pb and technogenic sands Pb > Zn > Cu.

  1. Optimization of the dissolution of molybdenum disks. FY-16 results

    Energy Technology Data Exchange (ETDEWEB)

    Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States); Rotsch, David A. [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey D. [Argonne National Lab. (ANL), Argonne, IL (United States); Bailey, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Krebs, John F. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    Argonne National Laboratory is providing technical development assistance to NorthStar Medical Technologies LLC in its pursuit of two pathways for production of molybdenum-99: the 98Mo(n,γ) 99Mo reaction and the photonuclear reaction, 100Mo(γ,n)99Mo. Processing of irradiated targets, from either production mode, requires dissolution of the target material in H2O2 followed by a concentration step, addition of ferric ion to precipitate impurities, and conversion of the final solution to 5M potassium hydroxide solution of potassium molybdate. Currently, NorthStar is using pressed and sintered Mo disks as targets. Several options are being considered for the design of Mo targets for the production of 99Mo using the (γ,n) reaction. In the current design, the target holder contains a series of sintered Mo disks lined up perpendicular to two incident electron beams, one entering from each side of the target stack. In this configuration, the front-most disks absorb most of the heat from the electron beam and need to be thinner to allow for better cooling, while the middle of the target can be thicker. Distribution of the total mass of Mo allows for larger masses of Mo material and thus larger production batches of 99Mo. A limitation of the sintering approach is the production of very thin disks. Recent advances in 3D printing allow for much thinner target components can be achieved than when the traditional press-and-sinter approach is used. We have demonstrated that several factors can play important roles in dissolution behavior: particle size of Mo metal used for production of targets, sintering conditions, degree of open porosity, and thickness of the sintered Mo targets. Here we report experimental results from studies of small-scale dissolution of sintered Mo disks fabricated from various recycled and commercial Mo materials, and dissolution of 3D-printed Mo disks that were

  2. SOLVENT EXTRACTION FOR URANIUM MOLYBDENUM ALLOY DISSOLUTION FLOWSHEET

    Energy Technology Data Exchange (ETDEWEB)

    Visser, A; Robert Pierce, R

    2007-06-07

    H-Canyon Engineering requested the Savannah River National Laboratory (SRNL) to perform two solvent extraction experiments using dissolved Super Kukla (SK) material. The SK material is an uranium (U)-molybdenum (Mo) alloy material of 90% U/10% Mo by weight with 20% 235U enrichment. The first series of solvent extraction tests involved a series of batch distribution coefficient measurements with 7.5 vol % tributylphosphate (TBP)/n-paraffin for extraction from 4-5 M nitric acid (HNO{sub 3}), using 4 M HNO{sub 3}-0.02 M ferrous sulfamate (Fe(SO3NH2)2) scrub, 0.01 M HNO3 strip steps with particular emphasis on the distribution of U and Mo in each step. The second set of solvent extraction tests determined whether the 2.5 wt % sodium carbonate (Na2CO3) solvent wash change frequency would need to be modified for the processing of the SK material. The batch distribution coefficient measurements were performed using dissolved SK material diluted to 20 g/L (U + Mo) in 4 M HNO{sub 3} and 5 M HNO{sub 3}. In these experiments, U had a distribution coefficient greater than 2.5 while at least 99% of the nickel (Ni) and greater than 99.9% of the Mo remained in the aqueous phase. After extraction, scrub, and strip steps, the aqueous U product from the strip contains nominally 7.48 {micro}g Mo/g U, significantly less than the maximum allowable limit of 800 {micro}g Mo/g U. Solvent washing experiments were performed to expose a 2.5 wt % Na2CO3 solvent wash solution to the equivalent of 37 solvent wash cycles. The low Mo batch distribution coefficient in this solvent extraction system yields only 0.001-0.005 g/L Mo extracted to the organic. During the solvent washing experiments, the Mo appears to wash from the organic.

  3. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal-Val, P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, H.J. (Akademie der Wissenschaften der DDR, Berlin)

    1984-08-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation.

  4. The wetting behaviour of silver on carbon, pure and carburized nickel, cobalt and molybdenum substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hula, Robert C., E-mail: robert.hula@tuwien.ac.at [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, A-1060 Wien (Austria); Edtmaier, Christian; Holzweber, Markus; Hutter, Herbert [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, A-1060 Wien (Austria); Eisenmenger-Sittner, Christoph [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A 1040 Wien (Austria)

    2010-05-01

    Properties such as thermal and electrical conductivity or the expansion behaviour of silver matrix composites with carbon based inclusions are strongly affected by the contact angle between carbon and silver. In order to promote wetting of carbon, insertion of metallic interlayers such as nickel, cobalt or molybdenum is a feasible approach. This paper presents contact angle measurements done with the sessile drop method on carbon substrates (glassy carbon, polycrystalline graphite) and on pure nickel, cobalt and molybdenum foils. The ability of these interlayer elements to lower the high contact angles of silver on glassy carbon (117 deg.) and polycrystalline graphite (124 deg.) under vacuum conditions was verified. Unlike nickel (30 deg.) and cobalt (26 deg.), molybdenum (107 deg.) nevertheless was not wettable by liquid silver (at 1273 K) under vacuum conditions. ToF-SIMS was used to identify oxygen on the surface, causing higher contact angles than expected. After oxide reduction a contact angle of 18 deg. on molybdenum was detected. Furthermore, the influence of carbon diffusion on the contact angle was investigated by gas phase carburization of the metal foils. ToF-SIMS and XRD identified dissolved carbon (Ni, Co) and carbide formation (Mo). However, only nickel and cobalt showed a slight decrease of the contact angle due to carbon uptake.

  5. A ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum sheet in thermal forming

    Directory of Open Access Journals (Sweden)

    Wang Chu

    2015-01-01

    Full Text Available Formability of pure molybdenum in thermal forming process has been greatly improved, but it is still hard to avoid the generation of rupture and other quality defects. In this paper, a ductile fracture criterion of pure molybdenum sheet in thermal forming was established by considering the plastic deformation capacity of material and stress states, which can be used to describe fracture behaviour and critical rupture prediction of pure molybdenum sheet during hot forming process. Based on the isothermal uniaxial tensile tests which performed at 993 to 1143 K with strain rate range from 0.0005 to 0.2 s−1, the material parameters are calculated by the combination method of experiment with FEsimulation. Based on the observation, new fracture criteria can be expressed as a function of Zener-Hollomon parameter. The critical fracture value that calculated by Oyane-Sato criterion increases with increasing temperature and decreasing strain rate. The ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum in thermal forming is proposed.

  6. Chemical Vapor Deposition of Atomically-Thin Molybdenum Disulfide (MoS2)

    Science.gov (United States)

    2015-03-01

    photoluminescence. 15. SUBJECT TERMS Chemical vapor deposition (CVD) Nanotechnology Molybdenum disulfide (MoS2) Raman spectroscopy 16...by ANSI Std. Z39.18 UNCLASSIFIED Approved for public release; distribution is unlimited. i CONTENTS Page Introduction 1...UNCLASSIFIED Approved for public release; distribution is unlimited. 1 INTRODUCTION Recently, an explosion of interest in low-dimensional

  7. Recovery of molybdenum using alumina microspheres and precipitation with selective organic reagents

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Fatima Maria Sequeira de; Abrao, Alcidio [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Dept. de Engenharia Quimica e Ambiental]. E-mail: fatimamc@net.ipen.br; aabrao@net.ipen.br

    1998-07-01

    In this paper is presented a study for the optimization of dissolution of the UAL{sub x} plates used for irradiation and production of radiomolybdenum. The alloy is dissolved in nitric acid with mercury as catalyst. The separation and concentration of the molybdenum was achieved using a chromatographic grade alumina microspheres column. the purified eluted molybdenum is finally precipitated using one of the selective reagents: alizarine blue, {alpha},{alpha}'- bipyridine and 1,10-phenanthroline. Any one of the obtained precipitate can be fired to the molybdenum trioxide. The interference of the following elements was studied: Re(VII), U(VI), Cr(VI), W(VI), V(V), Te(IV), Ti(IV), Zr(IV), Th(IV), Fe(III), Au(III), Ru(III), Al(III), Bi(III), Sb(III), Ce(IV), Pr(III), Sc(III), Y(III), Sm(III), Ba(II), Sr(II), Ni(II), Co(II), Cs(I). The molybdenum precipitates were characterized by gravimetric, CHN, TG, DTG, IR and X-ray diffraction analyses. (author)

  8. High-Sulfur-Vacancy Amorphous Molybdenum Sulfide as a High Current Electrocatalyst in Hydrogen Evolution

    KAUST Repository

    Lu, Ang-Yu

    2016-08-31

    The remote hydrogen plasma is able to create abundant S-vacancies on amorphous molybdenum sulfide (a-MoSx) as active sites for hydrogen evolution. The results demonstrate that the plasma-treated a-MoSx exhibits superior performance and higher stability than Pt in a proton exchange membrane based electrolyzers measurement as a proof-of-concept of industrial application.

  9. Electrosprayed molybdenum trioxide aqueous solution and its application in organic photovoltaic cells.

    Science.gov (United States)

    Suzuki, Katsumi; Fukuda, Takeshi; Liao, Yingjie

    2014-01-01

    A molybdenum trioxide thin film with smooth surface and uniform thickness was successfully achieved by an electrospray deposition method using an aqueous solution with a drastically low concentration of 0.05 wt%. Previous papers demonstrated that an additive solvent technique is useful for depositing the thin film by the electrospray deposition, and the high vapor pressure and a low surface tension of an additive solvent were found to be important factors. As a result, the smooth molybdenum trioxide thin film was obtained when the acetonitrile was used as the additive solvent. Furthermore, the vapor pressure of acetone is much higher than that of aqueous solution, and this indicates that the acetone is easily evaporated after spraying from the glass capillary. By optimizing a concentration of acetone in the molybdenum aqueous solution, a minimum root mean square roughness of the MoO3 thin film became 3.7 nm. In addition, an organic photovoltaic cell was also demonstrated using the molybdenum trioxide as a hole transport layer. Highest photoconversion efficiency was 1.72%, a value comparable to that using conventional thermal evaporation process even though the aqueous solution was used for the solution process. The photovonversion efficiency was not an optimized value, and the higher value can be achieved by optimizing the coating condition of the active layer.

  10. Electrosprayed molybdenum trioxide aqueous solution and its application in organic photovoltaic cells.

    Directory of Open Access Journals (Sweden)

    Katsumi Suzuki

    Full Text Available A molybdenum trioxide thin film with smooth surface and uniform thickness was successfully achieved by an electrospray deposition method using an aqueous solution with a drastically low concentration of 0.05 wt%. Previous papers demonstrated that an additive solvent technique is useful for depositing the thin film by the electrospray deposition, and the high vapor pressure and a low surface tension of an additive solvent were found to be important factors. As a result, the smooth molybdenum trioxide thin film was obtained when the acetonitrile was used as the additive solvent. Furthermore, the vapor pressure of acetone is much higher than that of aqueous solution, and this indicates that the acetone is easily evaporated after spraying from the glass capillary. By optimizing a concentration of acetone in the molybdenum aqueous solution, a minimum root mean square roughness of the MoO3 thin film became 3.7 nm. In addition, an organic photovoltaic cell was also demonstrated using the molybdenum trioxide as a hole transport layer. Highest photoconversion efficiency was 1.72%, a value comparable to that using conventional thermal evaporation process even though the aqueous solution was used for the solution process. The photovonversion efficiency was not an optimized value, and the higher value can be achieved by optimizing the coating condition of the active layer.

  11. Tungsten coating prepared on molybdenum substrate by electrodeposition from molten salt in air atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Fan; Zhang, Yingchun, E-mail: zycustb@163.com; Sun, Ningbo; Leng, Jiaxun

    2015-02-01

    Highlights: • Tungsten coatings were electroplated on molybdenum substrate for the first time. • The electrodeposition was studied in the air atmosphere. • The coating has columnar structure with preferential growth orientation of (1 1 0). • The columnar structure was disappeared after high-temperature annealing. • The coating has an extremely low oxygen content with the value of 0.032 wt%. - Abstract: Compact and smooth tungsten coating on molybdenum substrate was obtained by electrodeposition from Na{sub 2}WO{sub 4}–WO{sub 3} molten salt at 1173 K in atmosphere. Microstructure, morphology and properties were performed on the tungsten coating. The tungsten coating had columnar structure with the preferential growth orientation of (2 0 0). There was about 2 μm thick diffusion layer of tungsten in the molybdenum substrate. The bending test and thermal shock test showed the tungsten coating had good adhesion with the molybdenum substrate. The microhardness of the coating was about 492 HV and the oxygen content of the coating was 0.032 wt%. The high-temperature could enhance the high-temperature oxidation resistance and bond strength of the tungsten coating.

  12. Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, S R; Bonner, B P; Ryerson, F J; Hart, M M

    2006-01-27

    Pressure-volume relationships were measured at room temperature for eight granular materials and one specimen of epoxy foam. The granular materials included hollow ceramic microspheres, spherical molybdenum powder, Ottawa sand, aluminum, copper, titanium and silicon carbide powders and glassy carbon spheres. Measurements were made to 0.9 GPa in a liquid medium press for all of the granular materials and to 3 GPa in a solid medium press for the ceramic microspheres and molybdenum powder. A single specimen of epoxy foam was compressed to 30 MPa in the liquid medium press. Bulk moduli were calculated as a function of pressure for the ceramic microspheres, the molybdenum powder and three other granular materials. The energy expended in compacting the granular materials was determined by numerically integrating pressure-volume curves. More energy was expended per unit volume in compacting the molybdenum powder to 1 GPa than for the other materials, but compaction of the ceramic microspheres required more energy per gram due to their very low initial density. The merge pressure, the pressure at which all porosity is removed, was estimated for each material by plotting porosity against pressure on a semi-log plot. The pressure-volume curves were then extrapolated to the predicted merge pressures and numerically integrated to estimate the energy required to reach full density for each material. The results suggest that the glassy carbon spheres and the ceramic microspheres would require more energy than the other materials to attain full density.

  13. Tungsten and Molybdenum Ores in China and the Management Policies(Part Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>China is traditionally a leading producer of tungsten and molybdenum ores in the world. The ores are densely distributed and easy to exploit,and the production accounts for a large share of the world’s total.But China has yet to dominate the market and the advantage that China has long enjoyed is being weakened,giv-

  14. Process for reducing the oxygen content of biomass using molybdenum-based catalysts

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention concerns a process for converting biomass into useful organic building blocks for the chemical industry. The process involves the reduction of a polyol wherein at least two of the hydroxyl groups are located on adjacent carbon atoms in the presence of a molybdenum...

  15. Structural dynamics of gas-phase molybdenum nanoclusters : A transmission electron microscopy study

    NARCIS (Netherlands)

    Vystavel, T; Koch, SA; Palasantzas, G; De Hosson, JTM

    2005-01-01

    In this paper we study structural aspects of molybdenum clusters by transmission electron microscopy. The deposited clusters with sizes 4 nm or larger show a body-centered crystal (bcc) structure. The clusters are self-assembled from smaller structural units and form cuboids with a typical size of 4

  16. Inner Mongolia Wunugetu Copper & Molybdenum Mine Launched into Full-load Trial Run

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>Recently,the Inner Mongolia Wunugetu Moun-tain Copper and Molybdenum Mine officially entered full load trial operation stage.This Pro-ject is constructed by Inner Mongolia MiningCo Ltd under the China National Gold GroupCorporation with an initial investment of

  17. Favorable outcome in a newborn with molybdenum cofactor type A deficiency treated with cPMP

    NARCIS (Netherlands)

    Hitzert, Marrit M; Bos, Arend F; Bergman, Klasien A.; Veldman, Alex; Schwarz, Guenter; Santamaria-Araujo, José Angel; Heiner-Fokkema, Rebecca; Sival, Deborah A; Lunsing, Roelineke J; Arjune, Sita; Kosterink, Jos G W; van Spronsen, FrancJan

    2012-01-01

    Molybdenum cofactor deficiency (MoCD) is a lethal autosomal recessive inborn error of metabolism with devastating neurologic manifestations. Currently, experimental treatment with cyclic pyranopterin monophosphate (cPMP) is available for patients with MoCD type A caused by a mutation in the MOCS-1 g

  18. The impact of selenisation on damp heat degradation of the CIGS back contact molybdenum

    NARCIS (Netherlands)

    Theelen, M.; Tomassini, M.; Barreau, N.; Steijvers, H.; Branca, A.; Harel, S.; Vroon, Z.; Zeman, M.

    2012-01-01

    Molybdenum (Mo) degrades under the influence of damp heat, thereby reducing the output of CIGS PV. In this study, Mo layers were deposited on a glass substrate by magnetron sputtering, thereby varying the deposition pressure and the addition of selenium. These samples were thoroughly analysed and de

  19. The Sulfidation of gamma-Alumina and Titania Supported (Cobalt) Molybdenum Oxide Catalysts Monitored by EXAFS.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Leliveld, R.G.; Dillen, A.J. van; Geus, John W.

    1997-01-01

    The sulfidation of @c-alumina- and titania-supported(cobalt)molybdenum oxide catalysts has been studied with X-rayabsorption spectroscopy and temperature programmed sulfidation (TPS).The catalysts were stepwise sulfided at temperatures between 298 and673 K and their structure was determined with EXA

  20. Selective autooxidation of ethanol over titania-supported molybdenum oxide catalysts: structure and reactivity

    NARCIS (Netherlands)

    Caro, C.; Thirunavukkarasu, K.; Anilkumar, M.; Shiju, N.R.; Rothenberg, G.

    2012-01-01

    We study the selective catalytic oxidation of ethanol with air as a sustainable alternative route to acetaldehyde. The reaction is catalysed by molybdenum oxide supported on titania, in a flow reactor under ambient pressure. High selectivity to acetaldehyde (70%-89%, depending on the Mo loading) is