Ligand field effects in the nuclear magnetic shielding of nitrogen-15 and cobalt-59 in bent nitrosyl complexes of cobalt(III)

International Nuclear Information System (INIS)

Duffin, P.A.; Larkworthy, L.F.; Mason, J.; Stephens, A.N.; Thompson, R.M.

1987-01-01

A range of square-pyramidal complexes of cobalt(III) with a bent apical nitrosyl ligand has been prepared and examined by 15 N and 59 Co NMR spectroscopy, in a study of nephelauxetic and spectrochemical effects at the metal and nitrogen nuclei in the bent Co-NO chromophore. The basal ligands in this comparison include dithiocarbamate, quadridentate Schiff base or porphine, and bis-chelating diamine or oximate, so as to give S 4 , S 2 N 2 , N 4 , OONN, or ONON coordination in the plane and a range of substituents in the chelate and phenylene rings. The shielding of both cobalt and nitrogen tends to decrease with decrease in the M(d) → π*(NO) back-bonding, as indicated by the MN and NO bond distances, the MNO angle and the NO stretching frequency. The shieldings decrease from sulfur to nitrogen to oxygen coligators and also with electron withdrawal by ring substituents (and vice versa), i.e. with decrease in the ligand field splitting and in the nephelauxetism of the coligands. These parallelisms of the cobalt and nitrogen shielding accord with the orbital theory that was developed to explain the bending of the MNO ligand and influences of the metal and coligands. Significant interdependence of spectrochemical and nephelauxetic effects at cobalt and nitrogen arises from the degree of overlap and similarity in energies of the frontier orbitals for the paramagnetic circulation at nitrogen [n(N) → π* (NO)] and at cobalt (d-d). 43 references, 5 figures, 2 tables

Concerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization

KAUST Repository

Xia, Wei

2015-02-05

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides. CO2 saves: The deactivation of cobalt(III)-porphyrin and salen catalysts in propylene oxide/carbon dioxide copolymerization is systematically investigated, revealing a proposed mechanism for the catalyst reduction (see scheme).

Concerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization

KAUST Repository

Xia, Wei; Salmeia, Khalifah A.; Vagin, Sergei I.; Rieger, Bernhard

2015-01-01

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides. CO2 saves: The deactivation of cobalt(III)-porphyrin and salen catalysts in propylene oxide/carbon dioxide copolymerization is systematically investigated, revealing a proposed mechanism for the catalyst reduction (see scheme).

Studies of Binary Complexes of Tripodal Ligand cis,cis-1,3,5-tris(methylaminocyclohexane with Cr(III and Fe(III

Directory of Open Access Journals (Sweden)

S. Esakki Muthu

2005-01-01

Full Text Available The formation of binary complexes of Cr(III and Fe(III with a tripodal ligand cis,cis-1,3,5-tris(methylaminocyclohexane (tmach (L has been investigated in solution. The overall stability constants of tmach with Cr(III and Fe(III were determined by potentiometric method at an ionic strength of 0.1 M NaClO4 at 25±1°C in aqueous medium. The formation of species like MLH25+, MLH4+, ML3+, ML(OH2+ and ML(OH3 were observed. Fe(III was found to form more stable complexes than Cr(III. Molecular mechanics calculations were performed to explain the mode of coordination in solution.

Effect of heptadentate (N{sub 4}O{sub 3}) tripodal Schiff base ligand and its yttrium(III) complex on the luminescence and extraction of tris({beta}-diketonato)europium(III)

Energy Technology Data Exchange (ETDEWEB)

Hasegawa, Y. [Department of Chemistry, Faculty of Science, Science University of Tokyo, Tokyo 162-8601 (Japan)], E-mail: yhasegaw@rs.kagu.tus.ac.jp; Saitou, S.; Nagaoka, D.; Yajima, H. [Department of Chemistry, Faculty of Science, Science University of Tokyo, Tokyo 162-8601 (Japan); Kanesato, M. [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562 (Japan)

2008-02-28

In order to learn the effect of a Schiff base and the complex of Y{sup III} on the extraction of Eu{sup III} with {beta}-diketones and on the luminescence of the extracted species, the extraction of Eu{sup III} with 2-thenoyltrifluoroacetone (Htta) and/or these Schiff bases, tris(5-t-butyl)salicylidenaminoethyl amine (H{sub 3}L{sup 1}), and its Y{sup III} complex ([YL{sup 1}]) prepared, into CHCl{sub 3} was examined. Further, the luminescence and excited spectra of CHCl{sub 3} phases extracted Eu{sup III} complexes and the solutions containing tris({beta}-diketonato)Eu{sup III} and/or the Schiff bases were measured. On the measurement of the luminescence spectra, tris(pivaloyltrifluoroacetonato)Eu{sup III} (Eu(pta){sub 3}) as well as Eu(tta){sub 3} was used. Synergistic effect with Htta and these Schiff bases was observed. However, proper effect of Y{sup III} was not observed. The luminescence intensity of Eu(tta){sub 3} at 613 nm decreased with increasing concentration of H{sub 3}L{sup 1} or [YL{sup 1}], whereas that of Eu(pta){sub 3} increased with increasing concentration of the ligands, but no difference between both Schiff bases was observed, because of picking up of Y{sup III} from [YL{sup 1}] with the interaction between [YL{sup 1}] and water.

Phosphorescence Imaging of Living Cells with Amino Acid-Functionalized Tris(2-phenylpyridine)iridium(III) Complexes

NARCIS (Netherlands)

Steunenberg, P.; Ruggi, A.; Berg, van den N.S.; Buckle, T.; Kuil, J.; Leeuwen, van F.W.B.; Velders, A.H.

2012-01-01

A series of nine luminescent cyclometalated octahedral iridium(III) tris(2-phenylpyridine) complexes has been synthesized, functionalized with three different amino acids (glycine, alanine, and lysine), on one, two, or all three of the phenylpyridine ligands. All starting complexes and final

A New Approach toward Cyanotype Photography Using Tris-(Oxalato)ferrate(III): An Integrated Experiment

Science.gov (United States)

Fiorito, Pablo Alejandro; Polo, Andre´ Sarto

2015-01-01

This work presents an approach that integrates the preparation of a coordination compound, potassium tris- (oxalato)ferrate(III), with its photochemical behavior and provides a possible application, the printing of a photograph using the cyanotype technique. Through this experiment, students can be taught several concepts that occur in a…

Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

Science.gov (United States)

Maghami, Mahboobeh; Farzaneh, Faezeh; Simpson, Jim; Ghiasi, Mina; Azarkish, Mohammad

2015-08-01

A cobalt complex was prepared from CoCl2·6H2O and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in methanol and designated as [Co(tptz)(CH3OH)Cl2]·CH3OH·0.5H2O (1). It was characterized by several techniques including TGA analysis and FT-IR, UV-Vis and 1H NMR spectral studies. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The Co(II) metal center in 1 is six coordinated with a distorted octahedral geometry. The tptz ligand is tridentate and coordinates to the cobalt through coplanar nitrogen atoms from the triazine and two pyridyl rings. Two chloride anions and a methanol molecule complete the inner coordination sphere of the metal ion. The optimized geometrical parameters obtained by DFT calculation are in good agreement with single XRD data. The in vitro antibacterial activity of various tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) were evaluated against Gram-positive (Bacillus subtilis, Staphylococcus aureus and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Whereas all complexes exhibited good activity in comparison to standard antibacterial drugs, the inhibitory effects of complexes were found to be more than that of the parent ligand. Overall, the obtained results strongly suggest that the cobalt(II) complex is a suitable candidate for counteracting antibiotic resistant microorganisms.

Phosphorylated aminosugars: Synthesis, properties, and reactivity in enzymatic reactions

International Nuclear Information System (INIS)

Sem, D.S.; Cleland, W.W.

1991-01-01

A number of phosphorylated aminosugars have been prepared and tested as substrates for metabolic reactions. 6-Aminoglucose is a slow substrate for yeast hexokinase with a V max that is only 0.012% that of glucose. While V max is pH independent, V/K decreases below the pK of 9.0 of the amino group. 6-Aminoglucose is a competitive inhibitor vs glucose with a K i value increasing below the pK of 9 but leveling off at 33 mM below pH 7.16. Thus, protonation decreases binding affinity by 2.4 kcal/mol and only the neutral amine is catalytically competent. 6-Aminoglucose-6-P was synthesized enzymatically with hexokinase. Its pK's determined by 31 P NMR were 2.46 and 8.02 (α anomer) and 2.34 and 7.85 (β anomer), with a β:α ratio of 3.0. It is most stable at pH 12, while as a monoanion its half-life is 3 h. The 31 P NMR chemical shifts of the analogues are 8-8.5 ppm at pH 9.5. Their relative stability is 6-aminogluconate-6-P > 3-aminoglyceraldehyde-3-P > 6-aminoglucose-6-P > 6-aminofructose-1,6-bis-P≅6-aminofructose-6-P > 5-aminoribulose-5-P. These analogues were tested as substrates for their respective enzymes. Phosphorylated aminosugars are thus excellent isosteric analogues of normal metabolic intermediates, except for reactions catalyzed by kinases

GATA4-mediated cardiac hypertrophy induced by D-myo-inositol 1,4,5-tris-phosphate

International Nuclear Information System (INIS)

Zhu Zhiming; Zhu Shanjun; Liu Daoyan; Yu Zengping; Yang Yongjian; Giet, Markus van der; Tepel, Martin

2005-01-01

We evaluated the effects of D-myo-inositol 1,4,5-tris-phosphate on cardiac hypertrophy. D-myo-inositol 1,4,5-tris-phosphate augmented cardiac hypertrophy as evidenced by its effects on DNA synthesis, protein synthesis, and expression of immediate-early genes c-myc and c-fos, β-myosin heavy chain, and α-actin. The administration of D-myo-inositol 1,4,5-tris-phosphate increased the expression of nuclear factor of activated T-cells and cardiac-restricted zinc finger transcription factor (GATA4). Real-time quantitative RT-PCR showed that D-myo-inositol 1,4,5-tris-phosphate-induced GATA4 mRNA was significantly enhanced even in the presence of the calcineurin inhibitor, cyclosporine A. The effect of D-myo-inositol 1,4,5-tris-phosphate was blocked after inhibition of inositol-trisphosphate receptors but not after inhibition of c-Raf/mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (ERK) or p38 mitogen-activated protein kinase pathways. The study shows that D-myo-inositol 1,4,5-tris-phosphate-induced cardiac hypertrophy is mediated by GATA4 but independent from the calcineurin pathway

Coordination of different ligands to copper(II) and cobalt(III) metal centers enhances Zika virus and dengue virus loads in both arthropod cells and human keratinocytes.

Science.gov (United States)

Dutta, Shovan; Celestine, Michael J; Khanal, Supreet; Huddleston, Alexis; Simms, Colin; Arca, Jessa Faye; Mitra, Amlan; Heller, Loree; Kraj, Piotr J; Ledizet, Michel; Anderson, John F; Neelakanta, Girish; Holder, Alvin A; Sultana, Hameeda

2018-01-01

Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ligand-derived from citral (compound 3) and a cobalt(III) complex with a citral-thiosemicarbazone ligand (compound 4) increased DENV2 and ZIKV replication in both mosquito C6/36 cells and human keratinocytes (HaCaT cells). Treatment of both cell lines with compounds 2 or 4 showed increased dengue viral titers at all three tested doses. Enhanced dengue viral plaque formation was also noted at the tested dose of 100μM, suggesting higher production of infectious viral particles. Treatment with the compounds 2 or 4 enhanced ZIKV and DENV2 RNA levels in HeLa cell line and primary cultures of mouse bone marrow derived dendritic cells. Also, pre- or post treatments with conjugated compounds 2 or 4 showed higher loads of ZIKV or DENV2 envelope (E) protein in HaCaT cells. No changes in loads of E-protein were found in ZIKV-infected C6/36 cells, when compounds were treated after infection. In addition, we tested bis(1,10-phenanthroline)copper(II) chloride ([Cu(phen) 2 ]Cl 2 , (compound 5) and tris(1,10-phenanthroline)cobalt(III) chloride ([Co(phen) 3 ]Cl 3 , (compound 6) that also showed enhanced DENV2 loads. Also, we found that copper(II) chloride dehydrate (CuCl 2 ·2H 2 O) or cobalt(II) chloride hexahydrate (CoCl 2 ·6H 2 O) alone had no effects as "free" cations

Luminescence quenching of Ru(phen) by some polymer–cobalt(III ...

Indian Academy of Sciences (India)

TECS

2007-03-20

Mar 20, 2007 ... static binding between polymer-cobalt(III) complexes and DNA/micelles. Keywords. ... metal centres over long distances in proteins or protein pairs as a ..... curs predominantly at the interface of the dry core and the wet ethoxy ...

Probing the mer- to fac-isomerization of tris-cyclometallated homo- and heteroleptic (C,N)3 Iridium(III) complexes

NARCIS (Netherlands)

McDonald, A.R.; Lutz, M.; von Chrzanowski, L.S.; van Klink, G.P.M.; Spek, A.L.; van Koten, G.

2008-01-01

We have developed techniques which allow for covalent tethering, via a “hetero” cyclometallating ligand, of heteroleptic tris-cyclometallated iridium(III) complexes to polymeric supports (for application in light-emitting diode technologies). This involved the selective synthesis and thorough

Tris(trimethylsilyl)phosphate as electrolyte additive for self-discharge suppression of layered nickel cobalt manganese oxide

International Nuclear Information System (INIS)

Liao, Xiaolin; Zheng, Xiongwen; Chen, Jiawei; Huang, Ziyu; Xu, Mengqing; Xing, Lidan; Liao, Youhao; Lu, Qilun; Li, Xiangfeng; Li, Weishan

2016-01-01

Highlights: • TMSP is effective for self-discharge suppression of the charged NCM under 4.5 V. • TMSP oxidizes preferentially forming protective cathode interface film on NCM. • The film suppresses electrolyte decomposition and prevents NCM destruction. - Abstract: Application of layered nickel cobalt manganese oxide as cathode under higher potential than conventional 4.2 V yields a significant improvement in energy density of lithium ion battery. However, the cathode fully charged under high potential suffers serious self-discharge, in which the interaction between the cathode and electrolyte proceeds without potential limitation. In this work, we use tris(trimethylsilyl)phosphate (TMSP) as an electrolyte additive to solve this problem. A representative layered nickel cobalt manganese oxide, LiNi 1/3 Co 1/3 Mn 1/3 O 2 , is considered. The effect of TMSP on self-discharge behavior of LiNi 1/3 Co 1/3 Mn 1/3 O 2 is evaluated by physical and electrochemical methods. It is found that the self-discharge of charged LiNi 1/3 Co 1/3 Mn 1/3 O 2 can be suppressed significantly by using TMSP. TMSP is oxidized preferentially in comparison with the standard electrolyte during initial charging process forming a protective cathode interface film, which avoids the interaction between cathode and electrolyte at any potential and thus prevents electrolyte decomposition and protects LiNi 1/3 Co 1/3 Mn 1/3 O 2 from structure destruction.

Spectroscopic investigation on the interaction of some surfactant-cobalt(III) complexes with serum albumins

Energy Technology Data Exchange (ETDEWEB)

Vignesh, Gopalaswamy; Nehru, Selvan; Manojkumar, Yesaiyan; Arunachalam, Sankaralingam, E-mail: arunasurf@yahoo.com

2014-01-15

The interaction of HSA/BSA with single and double chain surfactant-cobalt(III) complexes, cis-[Co(phen){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (1), cis-[Co(phen){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (2), cis-[Co(en){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (3), cis-[Co(en){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (4), were investigated by steady state fluorescence, UV–vis absorption, synchronous, three dimensional fluorescence and circular dichroism spectroscopy. The results reveal that the quenching of HSA/BSA by all the four complexes takes place through static mechanism. The binding constant, binding sites and thermodymamic parameter were calculated. The results illustrate that the double chain surfactant-cobalt(III) complexes bind more strongly than the corresponding single chain complexes. The distance between donor (HSA/BSA) and acceptor (surfactant-cobalt(III) complexes) was obtained according to FRET. The results of synchronous, three dimensional and circular dichroism spectroscopy studies show that all the complexes caused considerable amount of conformational and some amount of environment changes in HSA/BSA. -- Highlights: • Binding of single and double chain surfactant-cobalt(III) complexes with serum albumins. • Hydrophobic attraction plays a major role in the binding process. • Binding induces considerable amount of conformational changes in the protein.

Cobalt(III)-oxo cubane clusters as catalysts for oxidation of organic ...

Indian Academy of Sciences (India)

been prepared by a general method and these have been characterized by analytical, spectroscopic, electro- chemical and ... alkylaromatics, alkenes and alcohols.1 Several indus- .... us to obtain the cobalt(III)-oxo clusters in good to very.

The electronic structure of adducts derived from tris(cyclopentadienyl)-lanthanide(III)

International Nuclear Information System (INIS)

Amberger, H.D.; Edelstein, N.M.

1985-01-01

On the basis of magneto-optical and optical data of adducts derived from tris (eta/sup 5/-cyclopentadienyl)-lanthanide(III) (Ln = Pr, Nd, Er) the underlying crystal field (CF) splitting patterns could be derived. Fitting the parameters of an empirical Hamiltonian to these CF splitting patterns, the CF eigenvalues and CF eigenfunctions were obtained. By means of these data the experimental temperature dependence of the paramagnetic susceptibility could be reproduced by choosing orbital reduction factors between 0.950 and 0.975, respectively. The contact contribution of the /sup 1/H-NMR shifts of the cyclopentadienide protons of Cp/sub 3/Pr . CNC/sub 6/H/sub 11/ could be simulated by adopting a hyperfine coupling parameter A/sub F/ = vertical bar 0.236 vertical bar MHz

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes.

Science.gov (United States)

Ushimaru, Richiro; Nishimura, Takuho; Iwatsuki, Toshiki; Naka, Hiroshi

2017-01-01

A fluorinated cobalt(III) porphyrin complex [Co(TPFPP)NTf 2 ·2C 2 H 5 OH, where TPFPP=5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, Tf=CF 3 SO 2 ] promotes hydroalkoxylation of alkynes to give acetals in good to excellent yields. The acetals can be directly functionalized with nucleophiles in a one-pot procedure.

THE COORDINATION COMPOUNDS OF COBALT (II, III WITH DITHIOCARBAMIC ACID DERIVATIVES — MODIFICATORS OF HYDROLYTIC ENZYMES ACTIVITY

Directory of Open Access Journals (Sweden)

L. D. Varbanets

2013-02-01

Full Text Available Chloride, bromide and isothiocyanate complexes of cobalt(II with N-substituted thiocarbamoyl-N?-pentamethylenesulfenamides (1–(12, and also complexes of cobalt(II, Ш with derivatives of morpholine-4-carbodithioic acid (13–(18 have been used as modificators of enzymes of hydrolytic action — Bacillus thurin-giensis ІМВ В-7324 peptidases, Bacillus subtilis 147 and Aspergillus flavus var. oryzae 80428 amylases, Eupenicillium erubescens 248 and Cryptococcus albidus 1001 rhamnosidases. It was shown that cobalt (II, Ш compounds influence differently on the activity of enzymes tested, exerted both inhibitory and stimulatory action. It gives a possibility to expect that manifestation of activity by complex molecule depends on ligand and anion presence — Cl–, Br– or NCS–. The high activating action of cobalt(II complexes with N-substituted thiocarbamoyl-N?-pentamethylenesulphenamides (1–(12 on elastase and fibrinolytic activity of peptidases compared to tris(4-morpholinecarbodithioatocobalt(ІІІ (14 and products of its interaction with halogens (15–(17, causes inhibitory effect that is probably due to presence of a weekly S–N link, which is easy subjected to homolytic breaking. The studies of influences of cobalt(II complexes on activity of C. аlbidus and E. еrubescens ?-Lrhamnosidases showed, that majority of compounds inhibits of its activity, at that the most inhibitory effect exerts to C. аlbidus enzyme.To sum up, it is possible to state that character of influence of cobalt(II complexes with N-substituted thiocarbamoyl-N?-pentamethylenesulphenamides, and also cobalt(II, Ш complexes with derivatives of morpholine-4-carbodithioic acid varies depending on both strain producer and enzyme tested. The difference in complex effects on enzymes tested are due to peculiarities of building and functional groups of their active centers, which are also responsible for binding with modificators.

Flow injection chemiluminescent determination of N-nitrosodimethylamine using photogenerated tris(2,2'-bipyridyl) ruthenium (III)

International Nuclear Information System (INIS)

Perez-Ruiz, Tomas; Martinez-Lozano, Carmen; Tomas, Virginia; Martin, Jesus

2005-01-01

A flow injection configuration was developed and evaluated for the chemiluminescent determination of N-nitrosodimethylamine. The method is based on the on-line cleavage of the N-NO bond of the nitrosamine by irradiation with ultraviolet light. The dimethylamine generated was subsequently reacted with tris(2,2'-bipyridyl) ruthenium (III), which was generated through the on-line photo-oxidation of tris(2,2'-bipyridyl) ruthenium (II) with peroxydisulfate. After selecting the best operating parameters, the emitted light showed a linear relationship with the concentration of N-nitrosodimethylamine between 1.5 and 148 ng ml -1 , with a detection limit of 0.29 ng ml -1 . The repeatability was 1.6% expressed as relative standard deviation (n = 10) and the reproducibility, studied on five consecutive days, was 3.2%. The sample throughput was 50 injections per hour. The method was applied to studying the recoveries of N-nitrosodimethylamine in water and different cured meat products

Synthesis, analysis and radiolysis of the cobalt III 8 hydroxyquinolinate complex

International Nuclear Information System (INIS)

Mestnik, S.A.C.; Silva, C.P.G. da.

1981-11-01

The cobalt III 8-hidroxyquinolinate complex was syntetized from a solution of cobalt II. The compound was analysed by IR absorption spectroscopy, elemental analysis and by the determination of number of ligands. The radiolytic degradation was verified by spectrophotometry after submitting samples of 10 - 3 M complex in ethanolic solution to different doses of gamma radiation from a 60 Co source. The change of maximum absorbance of the complex with different doses of gamma radiation and its UV-VIS absorption spectra are presented. The complex in the solid state was also irradiated with 6,9 Mrad of gamma radiation but it didn't present degradation. (Author) [pt

Cobalt(I) and Cobalt(III) Cyclopentadienyl Complexes with New Silicon-branched Fluorous Tags

Czech Academy of Sciences Publication Activity Database

Strašák, Tomáš; Čermák, Jan; Červenková Šťastná, Lucie; Sýkora, Jan; Fajgar, Radek

2014-01-01

Roč. 159, MAR 2014 (2014), s. 15-20 ISSN 0022-1139 R&D Projects: GA ČR(CZ) GAP106/12/1372 Institutional support: RVO:67985858 Keywords : fluorous tag * cobalt complex * cyclopentadienyl complex Subject RIV: CC - Organic Chemistry Impact factor: 1.948, year: 2014

The crystal structure of tris(thenoyltrifluoroacetonato)bis(triphenylphosphine oxide)neodymium(III)

International Nuclear Information System (INIS)

Leipoldt, J.G.; Bok, L.D.C.; Laubscher, A.E.; Basson, S.S.

1975-01-01

The crystal structure of tris(thenoyltrifluoroacetonato)bis= x (triphenylphosphine oxide)neodymium(III), (Nd(TTa) 3 .2TPPO), has been determined by single crystal X-ray diffraction. A total number of 5505 independent reflections was used for the structure determination. The complex crystallized in the triclinic space group P 1 - with two molecules in the unit cell. The cell dimensions are a = 23.64 A, b Z= 12.15 A, C 11.19 A, α = 109.4 0 , β = 104.2 0 , γ = 90.8 0 . The final calculated R vale is 8.4%. The molecule is monomeric and the neodymium atom is coordinated to eight oxygen atoms (six from the three thenoyltrifluoroacetone groups and two from the two triphenylphosphine groups) which form a dodecahedron. The average neodymium-oxygen bond length is 2.44 A. (author)

Crystal structures of two mononuclear complexes of terbium(III nitrate with the tripodal alcohol 1,1,1-tris(hydroxymethylpropane

Directory of Open Access Journals (Sweden)

Thaiane Gregório

2017-02-01

Full Text Available Two new mononuclear cationic complexes in which the TbIII ion is bis-chelated by the tripodal alcohol 1,1,1-tris(hydroxymethylpropane (H3LEt, C6H14O3 were prepared from Tb(NO33·5H2O and had their crystal and molecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris(hydroxymethylpropane]terbium(III nitrate dimethoxyethane hemisolvate, [Tb(NO32(H3LEt2]NO3·0.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-antiprismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-molecule of dimethoxyethane (completed by a crystallographic twofold rotation axis is also present. In product aquanitratobis[1,1,1-tris(hydroxymethylpropane]terbium(III dinitrate, [Tb(NO3(H3LEt2(H2O](NO32, 2, one bidentate nitrate ion and one water molecule are bound to the nine-coordinate terbium(III centre, while two free nitrate ions contribute to charge balance outside the tricapped trigonal-prismatic coordination polyhedron. No free water molecule was found in either of the crystal structures and, only in the case of 1, dimethoxyethane acts as a crystallizing solvent. In both molecular structures, the two tripodal ligands are bent to one side of the coordination sphere, leaving room for the anionic and water ligands. In complex 2, the methyl group of one of the H3LEt ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and intermolecular, are found in the crystal structures due to the number of different donor and acceptor groups present.

Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

International Nuclear Information System (INIS)

Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

1990-01-01

Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

Intramolecular electron transfer through a bridging carboxylate group coordinated to two cobalt(III)-ions

International Nuclear Information System (INIS)

Wieghardt, K.

1978-01-01

Reduction of the binuclear μ-p-nitrobenzoato -di-μ-hydroxo -bis[triammine cobalt(III)] cation with (CH 3 ) 2 COH radicals yields a radical cation with the p-nitrobenzoato radical being coordinated to two cobalt(III) ions at the carboxylic group. The unprotonated form of this species undergoes intramolecular electron transfer producing Co(II) (k = (3.3 +- 0.3). x 10 3 s -1 ). The role of the carboxylate group in the intramolecular electron transfer process is tentatively assessed in terms of an intramolecular outer-sphere reaction because of lack of overlap of the donor orbitals (π) and the acceptor orbital (sigma). The protonated form of the radical cation (pKsub(a) = 2.5) disproportionates via a bimolecular process without production of Co(II). The effect of two coordinated Co(III) ions as compared to only one on the properties of the nitrobenzoate radical anion are discussed. (orig.) 891 HK 892 GM [de

XAS Investigation of bio-relevant cobalt complexes in aqueous media

International Nuclear Information System (INIS)

Bresson, C.; Lamouroux, C.; Esnouf, S.; Solari, P.L.; Den Auwer, C.

2006-01-01

Cobalt is an essential element of biological cycles involved in numerous metallo-biomolecules, but it becomes a toxic element at high concentration or a radio-toxic element because of its use in the nuclear industry. 'Molecular speciation' in biological media is an essential prerequisite to evaluate its chemical behaviour as well as its toxic or beneficial effects. In this scheme, we have focused on the coordination properties of the thiol-containing amino acid cysteine (Cys) and the pseudo-peptide N-(2-mercapto-propionyl) glycine (MPG) towards the Co 2+ cation in aqueous media. XAS at the Co K edge and traditional spectroscopic techniques have been coupled in order to structurally characterize the cobalt coordination sphere. Oxidation states and geometries of the bis- and tris-cysteinato Co(III) complexes are in agreement with the literature data. In addition, bond lengths between the metallic centre and the donor atoms have been determined. The structure of a new dimeric N-(2-mercapto-propionyl) glycinato Co(II) complex in solution is also reported. The coordination of MPG to Co(II) through the thiolate and carboxylate functions is ascertained. This work provides fundamental structural information about bio-relevant complexes of cobalt, which will contribute to our understanding of the chemical behaviour and the biological role of this radionuclide. (authors)

Synthesis Characterization and Decomposition Studies of tris[N-N-dibenzyidithocarbaso)Indium (III) Chemical Spray Deposition of Polycrystalline CuInS2 on Copper Films

Science.gov (United States)

Hehemann, David G.; Lau, J. Eva; Harris, Jerry D.; Hoops, Michael D.; Duffy, Norman V.

2005-01-01

This paper presents the results of the synthesis characterization and decomposition studies of tris[N-N-dibenzyidithocarbaso)Indium (III) with chemical spray deposition of polycrystalline CuInS2 on Copper Films.

and cobalt(III) octahedral monomer complexes: Synthesis and ...

Indian Academy of Sciences (India)

In compound 2 the central cobalt is in +3 oxidation state while `in' compound 2, the nickel ion is in +2 oxidation state. The two complexes are isostructural with octahedral coordination environment exhibiting helical twist topology. They also display strong H-bonding as well as CH- interactions to generate 1D chain.

Kinetics of Oxidation of Cobalt(III Complexes of a Acids by Hydrogen Peroxide in the Presence of Surfactants

Directory of Open Access Journals (Sweden)

Mansur Ahmed

2008-01-01

Full Text Available Hydrogen peroxide oxidation of pentaamminecobalt(III complexes of α-hydroxy acids at 35°C in micellar medium has been attempted. In this reaction the rate of oxidation shows first order kinetics each in [cobalt(III] and [H2O2]. Hydrogen peroxide induced electron transfer in [(NH35 CoIII-L]2+ complexes of α-hydroxy acids readily yields 100% of cobalt(II with nearly 100% of C-C bond cleavage products suggesting that it behaves mainly as one equivalent oxidant in micellar medium. With unbound ligand also it behaves only as C-C cleavage agent rather than C-H cleavage agent. With increasing micellar concentration an increase in the rate is observed.

Electronic structure and optical properties of Eu(III) tris-β-diketonate adducts with 1,10-phenanthroline

Science.gov (United States)

Shurygin, A. V.; Korochentsev, V. V.; Cherednichenko, A. I.; Mirochnik, A. G.; Kalinovskaya, I. V.; Vovna, V. I.

2018-03-01

Adducts of tris-β-diketonates of the rare earth metal Eu(III) with 1,10-phenanthroline are studied by photoelectron spectroscopy and quantum chemistry methods. The electronic structure, peculiarities of the nature of chemical bonds, and the geometric structure of the adducts are determined. The interpretation of UV photoelectron spectra of vapors and X-ray photoelectron spectra of solid is carried out with the chosen technique. DFT/TDDFT methods make it possible to study the 1,10-phenanthroline molecule influence on the adduct electronic structure and to analyze the electronic effects of substitution of methyl groups by trifluoromethyl groups in the ligands. At transition from the tris-β-diketonate complexes to the adducts, it is observed an increase of the absorption region and a decrease in the energy gap that contributes to the efficiency growth in electronic excitation energy transfer in the ligand-metal. Moreover, phenanthroline displaces water groups, that are luminescence quenchers, from the first coordination sphere, closes coordination in the adduct, and blocks their further attachment. Both factors contribute to an increase in the luminescence intensity.

Bis({tris[2-(3,5-di-tert-butyl-2-oxidobenzylideneaminoethyl]amine}cerium(III diethyl ether solvate

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Peter Dröse

2010-11-01

Full Text Available The title compound, 2[Ce(C51H75N4O3]·C4H10O, was obtained in high yield (92% by reduction of (TRENDSALCeIVCl [TRENDSAL is N,N′,N′′-tris(3,5-di-tert-butylsalicylidenatoaminotriethylamine] with potassium in THF. The bulky tripodal TRENDSAL ligand effectively encapsulates the central CeIII cation with a Ce—N(imine distance of 2.860 (2 Å and an average C—N(amine distance of 2.619 Å within a distorted monocapped octahedral coordination.

Bibenzimidazole containing mixed ligand cobalt(III) complex as a selective receptor for iodide

Digital Repository Service at National Institute of Oceanography (India)

Indumathy, R.; Parameswarana, P.S.; Aiswarya, C.V.; Nair, B.U.

Two new mixed ligand cobalt(III) complexes containing bibenzimidazole (bbenzimH₂) ligand with composition [Co(phen)₂bbenzimH₂](ClO₄)₃ (1) and [Co(bpy)₂bbenzimH₂](ClO_4...

Crystal structures of fac-tri?chlorido?tris?(tri?methyl?phosphane-?P)rhodium(III) monohydrate and fac-tri?chlorido?tris?(tri?methyl?phosphane-?P)rhodium(III) methanol hemisolvate: rhodium structures that are isotypic with their iridium analogs

OpenAIRE

Merola, Joseph S.; Franks, Marion A.

2015-01-01

The crystal structures of two solvates of fac-tri-chlorido-tris-(tri-methyl-phosphane-κP)rhodium(III) are reported, i.e. one with water in the crystal lattice, fac-[RhCl3(Me3P)3]·H2O, and one with methanol in the crystal lattice, fac-[RhCl3(Me3P)3]·0.5CH3OH. These rhodium compounds exhibit distorted octahedral coordination spheres at the metal and are isotypic with the analogous iridium compounds previously reported by us [Merola et al. (2013 ▶). Polyhedron, 54, 67-73]. Comparison is made bet...

fac-Tris(pyridine-2-carboxyl­ato-κ2 N,O)cobalt(III)

Science.gov (United States)

Golenia, Irina A.; Boyko, Alexander N.; Kotova, Natalia V.; Haukka, Matti; Kalibabchuk, Valentina A.

2011-01-01

In the title compound, [Co(C6H4NO2)3], the CoIII ion lies on a threefold rotation axis and is in a distorted octa­hedral environment defined by three N and three O donor atoms from three fac-disposed pyridine-2-carboxyl­ate ligands. The ligands are coordinated in a chelate fashion, forming three five-membered rings. In the crystal, translationally related complex molecules are organized into columns along [001] via C—H⋯O hydrogen bonds. PMID:22219826

Cobalt(III) complexes of [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane. Report of an inert, chelate hydrogen carbonate ion

DEFF Research Database (Denmark)

Broge, Louise; Søtofte, Inger; Olsen, Carl Erik

2001-01-01

.H2O (3a). The coordination geometry around the cobalt(III) ion is a distorted octahedron with the inorganic ligands at cis-positions. Complex 2 is the second example of a cobalt(III) complex for which the X-ray structure,sfiows a chelate binding mode of the hydrogen carbonate entity. The pK(a) value...

Correlation between morphology and magnetic properties of electrochemically produced cobalt powder particles

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Maksimović Vesna M.

2015-01-01

Full Text Available Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, Energy Dispersive Spectroscopy (EDS analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exhibited a decreased saturation magnetization (MS, but an enhanced coercivity (HC which is explained by their peculiar morphology. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

Anionic carbonato and oxalato cobalt(III) nitrogen mustard complexes.

Science.gov (United States)

Craig, Peter R; Brothers, Penelope J; Clark, George R; Wilson, William R; Denny, William A; Ware, David C

2004-02-21

Synthetic approaches to cobalt(III) complexes [Co(L)(L')2] containing the bidentate dialkylating nitrogen mustard N,N-bis(2-chloroethyl)-1,2-ethanediamine (L = dce) together with anionic ancilliary ligands (L') which are either carbonato (CO3(2-)), oxalato (ox2-), bis(2-hydroxyethyl)dithiocarbamato (bhedtc-), 2-pyridine carboxylato (pico-) or 2-pyrazine carboxylato (pyzc-) were investigated. Synthetic routes were developed using the related amines N,N-diethyl-1,2-ethanediamine (dee) and 1,2-ethanediamine (en). The complexes [Co(CO3)2(L)]- (L = dee 1, dce 2), [Co(ox)2(L)]- (L = dee 3, dce 4), [Co(bhedtc)2(dee)]+ 5, [Co(bhedtc)2(en)]+ 6, mer-[Co(pico)3], mer-[Co(pyzc)]3 7 and [Co(pico)2(dee)]+ 8 were prepared and were characterised by IR, UV-Vis, 1H and 13C[1H] NMR spectroscopy, mass spectrometry and cyclic voltammetry. [Co(bhedtc)2(en)]BPh4 6b and trans(O)-[Co(pico)2(dee)]ClO4 8 were characterised by X-ray crystallography. In vitro biological tests were carried out on complexes 1-4 in order to assess the degree to which coordination of the mustard to cobalt attenuated its cytotoxicity, and the differential toxicity in air vs. nitrogen.

Removal of Cobalt Ion by Adsorbing Colloidal Flotation

Energy Technology Data Exchange (ETDEWEB)

Jung, In Ha; Lee, Jung Won [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-09-30

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(III) as flocculant and a sodium lauryl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., were considered. The flotation with Fe(III) showed 99.8% removal efficiency of cobalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution was treated with 35% H{sub 2}O{sub 2} prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of H{sub 2}O{sub 2}. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation wider. Foreign ions such as, NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, Na{sup +}, Ca{sup 2+} were adopted and their effects were observed, Of which sulfate ion was found to be detrimental to removal of cobalt ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in better removal efficiency of cobalt ion in the presence of sulfate ion. (author). 14 refs., 13 figs.

Development of Acoustic Devices Functionalized with Cobalt Corroles or Metalloporphyrines for the Detection of Carbon Monoxide at Low Concentration

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Meddy VANOTTI

2012-03-01

Full Text Available Progresses in synthetic chemistry methodologies has pushed to develop a large variety of artificial receptors of particular interest for chemical sensor applications. We investigate here the behavior of gas sensors based on surface acoustic wave (SAW devices. The use of Love waves that are specially sensitive to surface perturbation enables to exploit the molecular recognition processes occurring in non conductive sensing layers of cobalt corroles [5,10,15-Tris(2,6-dichlorophenylcorrolato]cobalt(III] for CO detection. We have monitored phase variations of Love-wave-based delay lines under various operation conditions and studied the detection efficiency of a differential version of our sensors. A test bench also has especially been developed to allow for the regeneration of the sensor by freeing the CO trapping sites and therefore to provide an accurate control of the operation conditions. The detection threshold reached using the proposed SAW sensor is experimentally found below one ppm.

Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique

International Nuclear Information System (INIS)

Sankar, Gopinathan; Fiddy, Steven; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham; Beale, Andrew M.

2007-01-01

Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III); DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state

Electron transfer. 88. Cobalt(III)-bound phosphite and hypophosphite

International Nuclear Information System (INIS)

Linn, D.E. Jr.; Gould, E.S.

1987-01-01

Phosphite and hypophosphite coordinate to cobalt(III) in (NH 3 ) 5 Co/sup III/ through oxygen, rather than through phosphorus. The resulting complexes undergo electron-transfer reactions with Ru(NH 3 ) 6 2+ much more slowly than with Eu 2+ or V 2+ , indicating that the latter two reactants preferentially utilize ligand bridging. Reductions with Cr 2+ are shown to accompanied by transfer of the phosphorus-containing ligands, and reaction of the protonated phosphito (biphosphito) derivative (pK/sub A/ = 3.06 at 23 0 C) proceeds through a combination of acid-independent and inverse-acid paths, both routes yielding the same phosphito-bound Cr(III) product. The hypophosphito, but not the biphosphito, complex reacts with Ce(IV), producing Co 2+ in an induced electron-transfer process. The yield of Co 2+ falls off progressively as [Ce/sup IV/] is increased, pointing to a sequence in which a Co(III)-bound P(II) radical is formed in initial attack by Ce(IV) but subsequently undergoes partition between competing reaction paths, i.e. internal electron transfer to Co(III) vs external oxidation by a second Ce(IV) center. The hypophosphito complex, but not the biphosphito complex, smoothly decomposes in basic media via an internal redox reaction, yielding Co(II) quantitatively, along with a 1:1 mixture of phosphite, and hypophosphite. This transformation, which fails with mixtures of (NH 3 ) 5 Co(H 2 O) 3+ and H 2 PO 2 - appears to be catalyzed specifically by OH - . Deuterium-labeling experiments disclose a solvent isotope effect. Reaction mechanisms are suggested for all the observed results. 54 references, 5 tables

Calcium ferrite formation from the thermolysis of calcium tris (maleato)

Indian Academy of Sciences (India)

For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to ...

Crystal structures of salicylideneguanylhydrazinium chloride and its copper(II) and cobalt(III) chloride complexes

International Nuclear Information System (INIS)

Chumakov, Yu. M.; Tsapkov, V. I.; Bocelli, G.; Antosyak, B. Ya.; Shova, S. G.; Gulea, A. P.

2006-01-01

The crystal structures of salicylideneguanylhydrazinium chloride hydrate hemiethanol solvate (I), salicylideneguanylhydrazinium trichloroaquacuprate(II) (II), and bis(salicylideneguanylhydrazino)cobalt(III) chloride trihydrate (III) are determined using X-ray diffraction. The structures of compounds I, II, and III are solved by direct methods and refined using the least-squares procedure in the anisotropic approximation for the non-hydrogen atoms to the final factors R = 0.0597, 0.0212, and 0.0283, respectively. In the structure of compound I, the monoprotonated molecules and chlorine ions linked by hydrogen bonds form layers aligned parallel to the (010) plane. In the structure of compound II, the salicylaldehyde guanylhydrazone cations and polymer chains consisting of trichloroaquacuprate(II) anions are joined by an extended three-dimensional network of hydrogen bonds. In the structure of compound III, the [Co(LH) 2 ] + cations, chloride ions, and molecules of crystallization water are linked together by a similar network

Cytotoxic property of surfactant-cobalt(III) complexes on a human breast cancer cell line.

Science.gov (United States)

Kumar, Rajendran Senthil; Riyasdeen, Anvarbatcha; Dinesh, Mohanakrishnan; Paul, Christo Preethy; Srinag, Suresh; Krishnamurthy, Hanumanthappa; Arunachalam, Sankaralingam; Akbarsha, Mohammad Abdulkadher

2011-07-01

The cancer chemotherapeutic potential of surfactant-cobalt(III) complexes, cis-[Co(bpy)(2)(C(14)H(29)NH(2))Cl](ClO(4))(2)·3 H(2)O (1) and cis-[Co(phen)(2)(C(14)H(29)NH(2))Cl](ClO(4))(2)·3 H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) on MCF-7 breast cancer cell was determined adopting MTT assay and specific staining techniques. The complexes affected the viability of the cells significantly and the cells succumbed to apoptosis as seen in the changes in the nuclear morphology and cytoplasmic features. Since the complex 2 appeared to be more potent, further assays were carried out on the complex 2. Single-cell electrophoresis indicated DNA damage. The translocation of phosphatidyl serine and loss of mitochondrial potential was revealed by annexin V-Cy3 staining and JC-1 staining respectively. Western blot analysis revealed up-regulation of pro-apoptotic p53 and down-regulation of anti-apoptotic Bcl-2 protein. Taken together, the surfactant-cobalt(III) complex 2 would be a potential candidate for further investigation for application as a chemotherapeutic for cancers in general and estrogen receptor-positive breast cancer in particular. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bowl adamanzanes--bicyclic tetraamines: syntheses and crystal structures of complexes with cobalt(III) and chelating coordinated oxo-anions.

Science.gov (United States)

Broge, Louise; Søtofte, Inger; Jensen, Kristian; Jensen, Nicolai; Pretzmann, Ulla; Springborg, Johan

2007-09-14

Seven cobalt(III) complexes of the macrobicyclic tetraamine ligand [2(4).3(1)]adamanzane ([2(4).3(1)]adz) are reported along with the crystal structure of six of these complexes. The solid state and solution structures are discussed, and a detailed assignment of the NMR spectra of the sulfato complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion (sulfate, formiate, nitrate, carbonate). Equilibration of these species with the corresponding diaqua complex is generally slow. The rates of equilibration in 5 mol dm(-3) perchloric acid at 25 degrees C have been measured, yielding half lives of 20 min, 10 min and 3 h for the sulfato, formiato and carbonato species respectively. The corresponding reaction for the nitrato complex occurs with a half life of less than 3 min. The concentration acid dissociation constant for the Co([2(4).3(1)]adz)(HCO(3))(2+) ion has been measured to K(a) = 0.33 mol dm(-3) [25 degrees C, I = 2 mol dm(-3)] and K(a) = 0.15 mol dm(-3) [25 degrees C, I = 5 mol dm(-3)]. The propensity for coordination of sulfate was found to be large enough for a quantitative conversion of the carbonato complex to the sulfato complex to occur in 3 mol dm(-3) triflic acid containing a small sulfate contamination. On this basis the decarboxylation in 5 mol dm(-3) triflic acid of the corresponding cobalt(III) carbonato complex of the larger macrobicyclic tetraamine ligand [3(5)]adz was reinvestigated and found to lead to the sulfato complex as well. The difference in exchange rate of the oxo-anion ligands for the cobalt(III) complexes of the two adamanzane ligands is discussed and attributed to fundamental differences in the molecular structure where an inverted configuration of the secondary non-bridged amine groups is seen for the complexes of the larger [3(5)]adz ligand. The high affinity for chelating coordination of oxo-anions for these two cobalt(iii)-adamanzane-moieties is rationalised on basis of the N-Co-N angles. N

Recovery of Cobalt as Cobalt Oxalate from Cobalt Tailings Using Moderately Thermophilic Bioleaching Technology and Selective Sequential Extraction

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Guobao Chen

2016-07-01

Full Text Available Cobalt is a very important metal which is widely applied in various critical areas, however, it is difficult to recover cobalt from minerals since there is a lack of independent cobalt deposits in nature. This work is to provide a complete process to recover cobalt from cobalt tailings using the moderately thermophilic bioleaching technology and selective sequential extraction. It is found that 96.51% Co and 26.32% Cu were extracted after bioleaching for four days at 10% pulp density. The mean compositions of the leach solutions contain 0.98 g·L−1 of Co, 6.52 g·L−1 of Cu, and 24.57 g·L−1 of Fe (III. The copper ion was then recovered by a solvent extraction process and the ferric ions were selectively removed by applying a goethite deironization process. The technological conditions of the above purification procedures were deliberately discussed. Over 98.6% of copper and 99.9% of ferric ions were eliminated from the leaching liquor. Cobalt was finally produced as cobalt oxalate and its overall recovery during the whole process was greater than 95%. The present bioleaching process of cobalt is worth using for reference to deal with low-grade cobalt ores.

Characterisation of different polymorphs of tris(8-hydroxyquinolinatoaluminium(III using solid-state NMR and DFT calculations

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Periasamy N

2009-11-01

Full Text Available Abstract Background Organic light emitting devices (OLED are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato-aluminium(III, known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. Results We report here 27Al one-dimensional (1D and two-dimensional (2D multiple-quantum magic-angle spinning (MQMAS NMR studies of the meridional (α-phase and the facial (δ-phase isomeric forms of Alq3. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory quantum-chemical calculations. We have also studied solvated phase of Alq3 containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the α-phase and the δ-phase, although the fluorescence emission shows no substantial difference between the α-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq3 has similar XRD patterns and quadrupolar parameters to that of the α-phase. Conclusion The 2D MQMAS experiments have shown that all the different modifications of Alq3 have 27Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq3 containing ethanol has structural difference from the α-phase of Alq3 (containing meridional isomer from the solid-state NMR studies

Crystal structure of [(1,2,3,4,11,12-η-anthracene]tris(trimethylstannylcobalt(III

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William W. Brennessel

2014-11-01

Full Text Available The asymmetric unit of the title structure, [Co(η6-C14H10{Sn(CH33}3], contains two independent molecules. Each anthracene ligand is η6-coordinating to a CoIII cation and is nearly planar [fold angles of 5.4 (3 and 9.7 (3°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co—C bond lengths to the ring junction carbon atoms than to the other four. Each CoIII cation is further coordinated by three Sn(CH33 ligands, giving each molecule a three-legged piano-stool geometry. In each of the two independent molecules, the trio of SnMe3 ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one molecule, the disorder ratio refined to 0.9365 (8:0.0635 (8, while that for the other refined to 0.9686 (8:0.0314 (8. The molecules are well separated, and thus no significant intermolecular interactions are observed. The compound is of interest as the first structure report of an η6-anthracene cobalt(III complex.

Titanium (III) cation selective electrode based on synthesized tris(2pyridyl) methylamine ionophore and its application in water samples

Science.gov (United States)

Rezayi, Majid; Karazhian, Reza; Abdollahi, Yadollah; Narimani, Leila; Sany, Seyedeh Belin Tavakoly; Ahmadzadeh, Saeid; Alias, Yatimah

2014-04-01

The introduction of low detection limit ion selective electrodes (ISEs) may well pave the way for the determination of trace targets of cationic compounds. This research focuses on the detection of titanium (III) cation using a new PVC-membrane sensor based on synthesized tris(2pyridyl) methylamine (tpm) ionophore. The application and validation of the proposed sensor was done using potentiometric titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). The membrane sensor exhibited a Nernstian response to the titanium (III) cation over a concentration range of 1.0 × 10-6-1.0 × 10-2 M and pH range from 1-2.5. The Nernstian slope, the lower of detection (LOD), and the response time (t95%) of the proposed sensor were 29.17 +/- 0.24 mV/dec, 7.9 × 10-7 M, and 20 s, respectively. The direct determination of 4-39 μg/ml of titanium (III) standard solution showed an average recovery of 94.60 and a mean relative standard deviation of 1.8 at 100.0 μg/ml. Finally, the utilization of the electrodes as end-point indicators for potentiometric titration with EDTA solutions for titanium (III) sensor was successfully carried out.

Synthesis, characterization and decomposition studies of tris(N,N-dibenzyldithiocarbamato)indium(III): chemical spray deposition of polycrystalline CuInS2 on copper films

International Nuclear Information System (INIS)

Hehemann, David G.; Lau, J. Eva; Harris, Jerry D.; Hoops, Michael D.; Duffy, Norman V.; Fanwick, Philip E.; Khan, Osman; Jin, Michael H.-C.; Hepp, Aloysius F.

2005-01-01

Tris(bis(phenylmethyl)carbamodithioato-S,S'), commonly referred to as tris(N,N-dibenzyldithiocarbamato)indium(III), In(S 2 CNBz 2 ) 3 , was synthesized and characterized by single crystal X-ray crystallography. The compound crystallizes in the triclinic space group P1-bar with two molecules per unit cell. The material was further characterized using a novel analytical system employing the combined powers of thermogravimetric analysis, gas chromatography/mass spectrometry, and Fourier transform infrared (FT-IR) spectroscopy to investigate its potential use as a precursor for the chemical vapor deposition (CVD) of thin film materials for photovoltaic applications. Upon heating, the material thermally decomposes to release CS 2 and benzyl moieties in to the gas phase, resulting in bulk In 2 S 3 . Preliminary spray CVD experiments indicate that In(S 2 CNBz 2 ) 3 decomposed on a Cu substrate reacts to produce stoichiometric CuInS 2 films

Synthesis, Characterization and Decomposition Studies of Tris(N,N-dibenzyldithiocarbamato) Indium(III): Chemical Spray Deposition of Polycrystalline CuInS2 on Copper Films

Science.gov (United States)

Hehemann, David G.; Lau, J. Eva; Harris, Jerry D.; Hoops, Michael D.; Duffy, Norman V.; Fanwick, Philip E.; Khan, Osman; Jin, Michael H.-C.; Hepp, Aloysius F.

2005-01-01

Tris(bis(phenylmethyl)carbamodithioato-S,S ), commonly referred to as tris(N,Ndibenzyldithiocarbamato) indium(III), In(S2CNBz2)3, was synthesized and characterized by single crystal X-ray crystallography. The compound crystallizes in the triclinic space group P1 bar with two molecules per unit cell. The material was further characterized using a novel analytical system employing the combined powers of thermogravimetric analysis, gas chromatography/mass spectrometry and Fourier-Transform infrared spectroscopy to investigate its potential use as a precursor for the chemical vapor deposition (CVD) of thin film materials for photovoltaic applications. Upon heating, the material thermally decomposes to release CS2 and benzyl moieties in to the gas phase, resulting in bulk In2S3. Preliminary spray CVD experiments indicate that In(S2CNBz2)3 decomposed on a Cu substrate reacts to produce stoichiometric CuInS2 films.

Genesis of Co/SiO2 catalysts : XAS study at the cobalt L-III,L- II absorption edges

NARCIS (Netherlands)

Bazin, D.; Kovacs, I.; Guczi, L.; Parent, P.; Laffon, C.; De Groot, F.; Ducreux, O.; Lynch, J.

2000-01-01

Silica-supported cobalt catalysts have been investigated by soft X-ray absorption techniques. Soft X-ray absorption spectra were collected at the Co LII,III edge during in situ reduction of calcined samples in a stream of hydrogen in the temperature range between 300 and 650°C. Using reference

Characterisation of different polymorphs of tris(8-hydroxyquinolinato)aluminium(III) using solid-state NMR and DFT calculations.

Science.gov (United States)

Goswami, Mithun; Nayak, Pabitra K; Periasamy, N; Madhu, P K

2009-11-09

Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. We report here 27Al one-dimensional (1D) and two-dimensional (2D) multiple-quantum magic-angle spinning (MQMAS) NMR studies of the meridional (alpha-phase) and the facial (delta-phase) isomeric forms of Alq3. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory) quantum-chemical calculations. We have also studied solvated phase of Alq3 containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the alpha-phase and the delta-phase, although the fluorescence emission shows no substantial difference between the alpha-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq3 has similar XRD patterns and quadrupolar parameters to that of the alpha-phase. The 2D MQMAS experiments have shown that all the different modifications of Alq3 have 27Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq3 containing ethanol has structural difference from the alpha-phase of Alq3 (containing meridional isomer) from the solid-state NMR studies. Solid-state NMR can hence be

Synthesis and novel fluorescence phenomenon of terbium(III) complex with N, N',N' -tris (2-benzimidazolmethyl) amine

International Nuclear Information System (INIS)

Yang, Tianlin; Gao, Min; Yang, Jinhui; Qin, Wenwu

2010-01-01

A benzimidazole ligand with a tripodal structure, N, N', N' -tris (2-benzimidazolmethyl) amine, and its terbium (III) complex has been synthesized. The complex has been characterized by element analysis, IR spectra, mass spectra, thermal analysis and molar conductivity. The terbium ion is found to coordinate with the nitrogen atoms (= N-) of imidazole ring and the bridgehead nitrogen atom. The fluorescence properties of the complex in aqueous solutions have been studied. Under excitation of UV light, the complex exhibits characteristic fluorescence of terbium ion. The luminescence of terbium complex in aqueous solutions is strongly enhanced by H + concentration. This phenomenon makes the new complex favorable for use in fluorescence switches and sensors. The mechanism of the fluorescence enhancement by protonation of the nitrogen atoms (-NH-) of imidazole ring is due to the suppressed photoinduced electron transfer fluorescence quenching on addition of acid. (author)

Synthesis, structure and photoluminescence of novel lanthanide (Tb(III), Gd(III)) complexes with 6-diphenylamine carbonyl 2-pyridine carboxylate

International Nuclear Information System (INIS)

An Baoli; Gong Menglian; Cheah, Kok-Wai; Wong, Wai-Kwok; Zhang Jiming

2004-01-01

A novel organic ligand, 6-diphenylamine carbonyl 2-pyridine carboxylic acid (HDPAP), and the corresponding lanthanide complexes, tris(6-diphenylamine carbonyl 2-pyridine carboxylato) terbium(III) (Tb-DPAP) and tris(6-diphenylamine carbonyl 2-pyridine carboxylato) gadolinium(III) (Gd-DPAP) have been designed and synthesized. The crystal structure and photoluminescence of Tb-DPAP and Gd-DPAP have been studied. The results showed that the lanthanide complexes have electroneutral structures, and the solid terbium complex emits characteristic green fluorescence of Tb(III) ions at room temperature while the gadolinium complex emits the DPAP ligand phosphorescence. The lowest triplet level of DPAP ligand was calculated from the phosphorescence spectrum of Gd-DPAP in N,N-dimethyl formamide (DMF) dilute solution determined at 77 K, and the energy transfer mechanisms in the lanthanide complexes were discussed. The lifetimes of the 5 D 4 levels of Tb 3+ ions in the terbium complex were examined using time-resolved spectroscopy, and the values are 0.0153±0.0001 ms for solid Tb(DPAP) 3 ·11.5H 2 O and 0.074±0.007 ms for 2.5x10 -5 mol/l Tb-DPAP ethanol solution

TRIS buffer in simulated body fluid distorts the assessment of glass-ceramic scaffold bioactivity.

Science.gov (United States)

Rohanová, Dana; Boccaccini, Aldo Roberto; Yunos, Darmawati Mohamad; Horkavcová, Diana; Březovská, Iva; Helebrant, Aleš

2011-06-01

The paper deals with the characterisation of the bioactive phenomena of glass-ceramic scaffold derived from Bioglass® (containing 77 wt.% of crystalline phases Na(2)O·2CaO·3SiO(2) and CaO·SiO(2) and 23 wt.% of residual glass phase) using simulated body fluid (SBF) buffered with tris-(hydroxymethyl) aminomethane (TRIS). A significant effect of the TRIS buffer on glass-ceramic scaffold dissolution in SBF was detected. To better understand the influence of the buffer, the glass-ceramic scaffold was exposed to a series of in vitro tests using different media as follows: (i) a fresh liquid flow of SBF containing tris (hydroxymethyl) aminomethane; (ii) SBF solution without TRIS buffer; (iii) TRIS buffer alone; and (iv) demineralised water. The in vitro tests were provided under static and dynamic arrangements. SBF buffered with TRIS dissolved both the crystalline and residual glass phases of the scaffold and a crystalline form of hydroxyapatite (HAp) developed on the scaffold surface. In contrast, when TRIS buffer was not present in the solutions only the residual glassy phase dissolved and an amorphous calcium phosphate (Ca-P) phase formed on the scaffold surface. It was confirmed that the TRIS buffer primarily dissolved the crystalline phase of the glass-ceramic, doubled the dissolving rate of the scaffold and moreover supported the formation of crystalline HAp. This significant effect of the buffer TRIS on bioactive glass-ceramic scaffold degradation in SBF has not been demonstrated previously and should be considered when analysing the results of SBF immersion bioactivity tests of such systems. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

1D and 2D Cobalt(II) Coordination Polymers, Co(ox)(en):Synthesis, Structures and Magnetic Properties

International Nuclear Information System (INIS)

Kang, Jae Un; Lee, Yu Mi; Kim, Seung Joo; Yun, Ho Seop; Do, Jung Hwan

2014-01-01

Two ethylenediamine cobalt(II) oxalate complexes Co(ox)(en), 1 and Co(ox)(en)·2H 2 O, 2 have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR spectrum, TG analysis, and magnetic measurements. In 1, Co atoms are coordinated by two bis-bidentate oxalate ions in transconfiguration to form Co(ox) chains, which are further bridged by ethylenediamine molecules to produce 2D grid layers, Co(ox)(en). In 2, Co atoms are coordinated by bridging oxalate ions in cis - configuration to form Co(ox) chains, and the additional chelation of ethylenediamine to Co atoms completes 1D zigzag chain, Co(en)(ox). Two lattice water molecules stabilize the chains through hydrogen bonding. Magnetic susceptibility measurements indicate that both complexes exhibit weak antiferromagnetic coupling between cobalt(II) ions with the susceptibility maxima at 23 K for 1 and 20 K for 2, respectively. In 1 and 2, the oxalate ligands afford a much shorter and more effective pathway for the magnetic interaction between cobalt ions compared to the ethylenediamine ligands, so the magnetic behaviors of both complexes could be well described with 1D infinite magnetic chain model

Carbon-Based Oxamate Cobalt(III) Complexes as Bioenzyme Mimics for Contaminant Elimination in High Backgrounds of Complicated Constituents.

Science.gov (United States)

Li, Nan; Zheng, Yun; Jiang, Xuemei; Zhang, Ran; Pei, Kemei; Chen, Wenxing

2017-10-12

Complex wastewater with massive components is now a serious environmental issue facing humanity. Selective removal of low-concentration contaminants in mixed constituents holds great promise for increasing water supplies. Bioenzymes like horseradish peroxidase exhibit oxidizing power and selectivity. Here, we manufactured its mimic through immobilizing non-heme oxamate anionic cobalt(III) complex ([Co III (opba)] - , opba = o-phenylenebis(oxamate)) onto pyridine (Py) modified multiwalled carbon nanotubes ([Co III (opba)] - -Py-MWCNTs, MWCNTs = multiwalled carbon nanotubes), where MWCNTs captured substrates and Py functioned as the fifth ligand. We chose typical azo dye (C.I. Acid Red 1) and antibiotic (ciprofloxacin) as model substrates. Without •OH, this catalyst could detoxify target micropollutants efficiently at pH from 8 to 11. It also remained efficient in repetitive tests, and the final products were non-poisonous OH-containing acids. Combined with radical scavenger tests and electron paramagnetic resonance result, we speculated that high-valent cobalt-oxo active species and oxygen atom transfer reaction dominated in the reaction pathway. According to density functional theory calculations, the electron spin density distribution order showed that electron-withdrawing ligand was beneficial for inward pulling the excess electron and lowering the corresponding energy levels, achieving an electrophilic-attack enhancement of the catalyst. With target removal property and recyclability, this catalyst is prospective in water detoxication.

Manipulating radicals: Using cobalt to steer radical reactions

OpenAIRE

Chirilă, A.

2017-01-01

This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

Spinterface between tris(8-hydroxyquinoline)metal(III) molecules and magnetic surfaces: a first-principles study

Science.gov (United States)

Jiang, W.; Wang, Jingying; Dougherty, Daniel; Liu, Feng; Feng Liu Team; Daniel Dougherty Team

Using first-principles calculations, we have systematically investigated the hybridization between tris(8-hydroxyquinoline)metal(III) (Mq3, M = Fe, Cr, Al) molecules and magnetic substrates (Co and Cr). Mq3 with different central metal elements but the same organic framework has dramatically different interaction with different magnetic substrates, which affect the interface state significantly. AFM coupling was observed between magnetic Mq3 molecules and ferromagnetic (Co) as well as antiferromagnetic (Cr) substrate, manifested with a superexchange and direct exchange interaction, respectively. Such strong magnetic interfacial coupling may open a gap around the Fermi level and significantly change interface transport properties. Nonmagnetic Alq3 molecule was found to enhance the interface spin polarization due to hybridization between the lowest unoccupied molecular orbitals (LUMO) of Alq3 and metallic surface state. These findings will help better understand spinterface and shed new light on future application of Mq3 molecules in spintronics devices. This work was support by NSF-MRSEC (DMR-1121252) and DOE-BES (DE-FG02-04ER46148).

Radiation induced ligand loss from cobalt complexes

International Nuclear Information System (INIS)

Funston, A. M.; McFadyen, W.D.; Tregloan, P.A.

2000-01-01

Full text: Due to the rapid nature of ligand dissociation from cobalt(II) complexes the study of the rate of ligand dissociation necessitates the use of a technique such as pulse radiolysis. This allows the rapid reduction of the corresponding cobalt(III) complex by a reducing radical, such as the aquated electron, to form the cobalt(II) complex. However, to date, no systematic study of either the mechanism of reduction or the influence of the electronic structure on the rate of ligand dissociation has been carried out. In order to understand these processes more fully the mechanism of reduction of a range of related cobalt(III) complexes by the aquated electron and the subsequent rate of ligand dissociation from the resulting cobalt(II) complexes is being investigated. It has been found that a number of processes are observed following the initial rapid reaction of the cobalt(III) complex with the aquated electron. Ultimately ligand loss is observed. Depending upon the complex, the initial processes observed may include the formation of coordinated radicals and electron transfer within the complex. For complexes containing aromatic ligands such as 2,2'-bipyridine, 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine the formation of a coordinated radical is observed as the initial reduction step. The kinetics of ligand dissociation of these complexes has been determined. The loss of monodentate ligands is fast and has been indistinguishable from the reduction processes when aromatic ligands are also present in the complex. However, for diamine chelates and diimine chelates spectra of the transient species can be resolved

Tris-(1,3-diaryltriazenide) complexes of rhodium – Synthesis ...

Indian Academy of Sciences (India)

Administrator

structure and, spectral and electrochemical properties. CHHANDASI ... Cl, NO2) with [Rh(PPh3)2(CO)Cl] in ethanol in the presence of NEt3 produces a series of tris- ... Rh(III)–Rh(IV) oxidation (within 0⋅84–1⋅67 V vs SCE), followed by an oxidation of the coordinated tri- ..... bient temperature (298 K) all the complexes have.

Cobalt Ion Promoted Redox Cascade: A Route to Spiro Oxazine-Oxazepine Derivatives and a Dinuclear Cobalt(III) Complex of an N-(1,4-Naphthoquinone)-o-aminophenol Derivative.

Science.gov (United States)

Mondal, Sandip; Bera, Sachinath; Maity, Suvendu; Ghosh, Prasanta

2017-11-06

The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-aminophenol derivatives (L R H 2 ) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. L R H 2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2-) (L R 2- ) and SQ-N-(1,4-naphthoquinone) (L R •- ) states in the complexes. Reactions of L R H 2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine derivatives ( OX L R ) in good yields, when R = H, Me, t Bu. Spiro oxazine-oxazepine derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of L R H 2 → OX L R in MeOH is a (6H + + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C-O coupling reactions, where MeOH is the source of a proton and the ester function. It was established that the active cascade precursor is [(L Me •- )Co III Cl 2 ] (A). Notably, formation of a spiro derivative was not detected in CH 3 CN and the reaction ends up furnishing A. The route of the reaction is tunable by R, when R = NO 2 , it is a (2e + 4H + ) oxidation reaction affording a dinuclear L R 2- complex of cobalt(III) of the type [(L NO2 2- ) 2 Co III 2 (OMe) 2 (H 2 O) 2 ] (1) in good yields. No cascade occurs with zinc(II) ion even in MeOH and produces a L Me •- complex of type [(L Me •- )Zn II Cl 2 ] (2). The intermediate A and 2 exhibit strong EPR signals at g = 2.008 and 1.999, confrming the existence of L Me •- coordinated to low-spin cobalt(III) and zinc(II) ions. The intermediates of L R H 2 → OX L R conversion were analyzed by ESI mass spectrometry. The molecular geometries of OX L R and 1 were confirmed by X-ray crystallography, and the spectral features were elucidated by TD DFT calculations.

Kinetics and mechanism of aquation and formation reactions of carbonato complexes. XII. Deuterium solvent isotope effect on the rate of acid-catalyzed decarboxylation of the carbonatobis (ethylenediamine) cobalt(III) complex ion. A mechanistic reappraisal

International Nuclear Information System (INIS)

Harris, G.M.; Hyde, K.E.

1978-01-01

A recent study of the acid-catalyzed decarboxylation of the carbonatotetrakis(pyridine)cobalt(III) complex ion showed there to be rate acceleration in D 2 O solvent, consistent with a proton-preequilibration mechanism. This observation directly contradicts the results of a similar study made some years ago of the analogous ion, carbonatobis(ethylenediamine)cobalt(III), for which there appeared to be deceleration in D 2 O solvent. A reinvestigation of the latter reaction over a much wider acidity range has now shown the earlier work to be in error. The previously proposed generalized mechanism for aquation of chelated carbonato complex ions of the form CoN 4 CO 3 + (N 4 identical with various tetramine ligand groupings of uni-, bi-, or quadridentate type) has thus been revised to include a proton equilibration step. An unexpected complication arises in the interpretation of the data for the bis(ethylenediamine) complex ion in the acidity range 0.1 + ] + ] term, overtakes and exceeds the true first-order rate constant for CO 2 release. The interesting implications of this unusual first-order successive reaction system are fully explored in the context of the present study

Nickel acts as an adjuvant during cobalt sensitization

DEFF Research Database (Denmark)

Bonefeld, Charlotte Menne; Nielsen, Morten Milek; Vennegaard, Marie T.

2015-01-01

Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We...... investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found...... that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses...

Synergistic extraction of Eu(III) with N-phosphorylated bis-ureas and chlorinated cobalt bis(dicarbollide) ion

Energy Technology Data Exchange (ETDEWEB)

Selucky, P.; Bubenikova, M.; Rais, J. [UJV Rez, a.s., Rez near Prague (Czech Republic); Gruener, B. [Academy of Sciences of the Czech Republic, Rez near Prague (Czech Republic). Inst. of Inorganic Chemistry; Brusko, V.V. [JSC NIIneftepromchim, Kazan (Russian Federation)

2013-03-01

Extraction of Eu(III) with a synergistic mixture of polydentate N-phosphorylated bis-ureas with the general formula (i-PrO){sub 2}P(O)NHC(O)NHXNHC(O)NHP(O)(Oi-Pr){sub 2} (X = (CH{sub 2}){sub 7}, (CH{sub 2}){sub 2}O(CH{sub 2}){sub 2} and (CH{sub 2}){sub 2}O(CH{sub 2}){sub 2}O(CH{sub 2}){sub 2}) and chlorinated cobalt bis(dicarbollide) ion (CCD-) with formula closo-[(1,2-C{sub 2}B{sub 9}H{sub 8}Cl{sub 3}){sub 2}-3-Co]{sup -} was studied using nitrobenzene as the solvent. Extraction of Eu(III) was very effective up to high concentrations of nitric acid. Eu(III) is most likely extracted into the organic phase as the [EuL{sub 2}]{sup 3+} species whereas the positive charge of extracted complex is compensated by CCD and/or nitrate anions. (orig.)

Ultraviolet determination of cobalt (III) with EDDHA (Ethylenediam-ine N N' bis o-Hydroxyphenilacetic acid)

International Nuclear Information System (INIS)

Herrero, C.; Bollain, M.H.; Bermejo, F.

1990-01-01

A method for the u.v. determination of cobalt with EDDHA is proposed. Between pH 4-7 the spectrum show and absorption maximum at 255 nm. The effect of amount of reagent, anount of oxidant, acidity, time and temperature have also been studied. Beer's Law is obeyed over the range 0.1 to 2,34 μg Co(III) mL -1 with a minimum photometric error of 3.0%. The molar absortivity was (2.71 ± 0.02) 10 4 L mol -1 cm -1 . The reproducibility, precision, stoichiometry of the complex and interferences have been investigated. (Author)

The effect of heterocyclic S,S’-ligands on the electrochemical properties of some cobalt(III complexes in acid

Directory of Open Access Journals (Sweden)

V. M. JOVANOVIC

2005-02-01

Full Text Available Eight mixed-ligand cobalt(III complexes with the macrocyclic amine 1,4,8,11-tetraazacyclotetradecane (cyclam and a heterocyclic dithiocarbamate (Rdtc- i.e., morpholine- (Morphdtc, thiomorpholine- (Timdtc, piperazine- (Pzdtc, N-methylpiperazine-(Mepzdtc, piperidine- (Pipdtc, 2-, 3- or 4-methylpiperidine- (2-, 3- and 4-Mepipdtc carbodithionato-S,S ions, of the general formula [Co(cyclamRdtc](ClO42, were investigated in deoxygenated 0.1MHClO4 solutions. Cyclic voltammetry data at a glassy carbon (GC electrode demonstrate a redox reaction of cobalt(III from the complexes at potentials strongly influenced by the presence of different heterocyclic Rdtc- ligands. In this respect, the complexes were separated into two groups: the first, with a heteroatom O, S or N in the heterocyclic ring, and the second, with a methyl group on the piperidine ring of the Rdtc- ligand. Anodic polarization of an Fe electrode in the presence of the complexes shows their influence not only on the dissolution of iron but also on the hydrogen evolution reactions and on this basis complexes the complexes could be divided into the same two groups. It was found that the weaker the inhibiting effect of the free heterocyclic amines is, the significantly higher is the efficiency of the corresponding complexes.

Effect of dissimilatory Fe(III) reducers on bio-reduction and nickel-cobalt recovery from Sukinda chromite-overburden.

Science.gov (United States)

Esther, Jacintha; Panda, Sandeep; Behera, Sunil K; Sukla, Lala B; Pradhan, Nilotpala; Mishra, Barada K

2013-10-01

The effect of an adapted dissimilatory iron reducing bacterial consortium (DIRB) towards bio-reduction of Sukinda chromite overburden (COB) with enhanced recovery of nickel and cobalt is being reported for the first time. The remarkable ability of DIRB to utilize Fe(III) as terminal electron acceptor reducing it to Fe(II) proved beneficial for treatment of COB as compared to previous reports for nickel leaching. XRD studies showed goethite as the major iron-bearing phase in COB. Under facultative anaerobic conditions, goethite was reduced to hematite and magnetite with the exposure of nickel oxide. FESEM studies showed DIRB to be associated with COB through biofilm formation with secondary mineral precipitates of magnetite deposited as tiny globular clusters on the extra polymeric substances. The morphological and mineralogical changes in COB, post DIRB application, yielded a maximum of 68.5% nickel and 80.98% cobalt in 10 days using 8M H2SO4. Copyright © 2013 Elsevier Ltd. All rights reserved.

Construction of an apparatus for nuclear orientation measurements at low temperatures. Application to neodymium-cobalt alloy; Realisation d'un appareil pour des mesures d'orientation nucleaire a basse temperature. Application a l'alliage neodyme-cobalt

Energy Technology Data Exchange (ETDEWEB)

Mayer, E [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1965-10-01

We describe experiments along which has been studied the anisotropy of {gamma} radiations emitted by oriented nuclei. We have used the great hyperfine fields acting on nuclei in ferromagnetic metals so as to produce alignment at low temperature. By irradiation we obtained a few cobalt 60 nuclei in our samples which were then cooled down to 0,01 K. The anisotropic rate of the 1,33 MeV {gamma} radiation was measured in function of the sample temperature, using as thermometer the anisotropy of {gamma} radiation emitted by cobalt 60 nuclei in a cobalt single crystal. Cobalt 60 was lined up in a cobalt nickel alloy (40% Ni). The hyperfine field at the cobalt was measured compared to the effective field in metallic cobalt: Heff(Co Ni)/Heff(Co metal) = 0.71 {+-} 0.12. These results are in good agreement with specific heat measurements made previously. Cobalt 60 has been polarised in a neodymium-cobalt alloy (NdCo{sub 5}). The field at the cobalt in NdCo{sub 5} has been measured compared to the field in metallic cobalt and taking the non-saturation into account we found 165000 oersteds < Heff(NdCo{sub 5}) < 220000 oersteds. (author) [French] Nous decrivons des experiences au cours desquelles nous avons etudie l'anisotropie de rayonnements {gamma} emis par des noyaux orientes. Nous avons utilise les grands champs hyperfins agissant sur las noyaux dans les metaux ferromagnetiques pour produire l'alignement a basse temperature. Par irradiation nous avons obtenu quelques noyaux de cobalt 60 dans nos echantillons qui furent ensuite refroidis a 0,01 K. Le degre d'anisotropie du rayonnement {gamma} de 1,33 MeV fut mesure en fonction de la temperature de l'echantillon en utilisant l'anisotropie du rayonnement {gamma} de noyaux de cobalt 60 dans un monocristal de cobalt metallique utilise comme thermometre. Le cobalt 60 a ete aligne dans un alliage de cobalt-nickel (40% Ni). Le champ hyperfin au niveau du cobalt a ete mesure par rapport au champ effectif dans le cobalt metallique

Soluble dendrimers europium(III) β-diketonate complex for organic memory devices

International Nuclear Information System (INIS)

Wang Binbin; Fang Junfeng; Li Bin; You Han; Ma Dongge; Hong Ziruo; Li Wenlian; Su Zhongmin

2008-01-01

We report the synthesis of a soluble dendrimers europium(III) complex, tris(dibenzoylmethanato)(1,3,5-tris[2-(2'-pyridyl) benzimidazoly]methylbenzene)-europium(III), and its application in organic electrical bistable memory device. Excellent stability that ensured more than 10 6 write-read-erase-reread cycles has been performed in ambient conditions without current-induced degradation. High-density, low-cost memory, good film-firming property, fascinating thermal and morphological stability allow the application of the dendrimers europium(III) complex as an active medium in non-volatile memory devices

Tris(2,2′-bipyridine-κ2N,N′cobalt(III bis[bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6cobaltate(III] perchlorate dimethylformamide hemisolvate 1.3-hydrate

Directory of Open Access Journals (Sweden)

Irina A. Golenya

2012-10-01

Full Text Available In the title compound, [Co(C10H8N23][Co(C7H3NO42]2(ClO4·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudooctahedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxylate O atoms of two doubly deprotonated pyridine-2,6-dicarboxylate ligands in a distorted octahedral geometry. One dimethylformamide solvent molecule and two water molecules are half-occupied and one water molecule is 0.3-occupied. O—H...O hydrogen bonds link the water molecules, the perchlorate anions and the complex anions. π–π interactions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3 Å].

Tris(8-hydroxyquinoline)aluminum (III) (Alq3) nanowires templated from an eggshell membrane

Energy Technology Data Exchange (ETDEWEB)

Lee, Tu, E-mail: tulee@cc.ncu.edu.t [Department of Chemical and Materials Engineering, National Central University, 300 Jhong-Da Rd, Jhong-Li City 320, Taiwan (China); Chang, Shih Chia; Peng, Jen Fan [Department of Chemical and Materials Engineering, National Central University, 300 Jhong-Da Rd, Jhong-Li City 320, Taiwan (China)

2010-07-30

One to 2-{mu}m long, {<=} 400-nm wide amorphous tris(8-hydroxyquinoline)aluminum (III) (Alq3) nanowires (NWs) grown from the 15-min boiled outer shell membrane (OSM) of the hen's egg and from the OSM solution cast film via thermal evaporation with a source temperature of 260 {sup o}C and a substrate temperature of 138 {sup o}C under 6.7 x 10{sup -2} Pa gave about 1.4 to 1.7 times more photoluminescence emission than the control Alq3 sample did, which was grown from the plain glass surface. The characteristic bonding energies of C 1s X-ray photoelectron signal at 282 eV, O 1s signal at 529 eV and N 1s signal at 397 eV suggested that the relatively high NW density for the 15-min boiled OSM and the OSM solution cast film, was mainly caused by the formation of the O=C-O-C=O anhydride moiety and the C=N group in the proteinaceous OSM at high temperature of 90 {sup o}C to 100 {sup o}C. Therefore, we proposed that the 15-min boiled OSM and the OSM solution cast film apparently served as good templates by providing nano-regions of high concentration of the O=C-O-C=O anhydride groups and the C=N groups for nesting the Alq3 gas molecules to form nano-conical Alq3 nuclei for the growth of long and narrow NWs.

Emission properties of Sm(III) complex having ten-coordination structure

International Nuclear Information System (INIS)

Hasegawa, Yasuchika; Tsuruoka, Shin-ichi; Yoshida, Takahiko; Kawai, Hideki; Kawai, Tsuyoshi

2008-01-01

Sammarium(III) complex having ten-coordination structure, bis-(1,10-phenanthroline)tris-(hexafluoroacetylacetonato)samarium(III) (Sm(hfa) 3 (phen) 2 ) was prepared by chelation of tris-(hexafluoroacetylacetonato) samarium(III) (Sm(hfa) 3 (H 2 O) 2 ) with 1,10-phenantroline (phen). The characteristic ten-coordination structure of Sm(hfa) 3 (phen) 2 was determined by 1 H NMR and elemental analyses. Strong deep-red emission (λ max =643 nm) and narrow emission band (FWHM=5 nm) of Sm(hfa) 3 (phen) 2 originated from electronic allowed transition from characteristics ten coordinate structure. The emission quantum yields Sm(hfa) 3 (phen) 2 excited at absorption bands of ligands and Sm(III) ion were found to be 0.36 and 1.4%, respectively

Cobalt(III) complex

Indian Academy of Sciences (India)

Administrator

e, 40 µM complex, 10 hrs after dissolution, f, 40 µM complex, after irradiation dose 15 Gy. and H-atoms result in reduction of Co(III) to Co. (II). 6. It is interesting to see in complex containing multiple ligands what is the fate of electron adduct species formed by electron addition. Reduction to. Co(II) and intramolecular transfer ...

Electron transfer reactions of macrocyclic compounds of cobalt

Energy Technology Data Exchange (ETDEWEB)

Heckman, R.A.

1978-08-01

The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

Ultraviolet determination of cobalt (III) with EDDHA (Ethylenediam- ine N N' bis o-Hydroxyphenilacetic acid)

Energy Technology Data Exchange (ETDEWEB)

Herrero, C.; Bollain, M.H.; Bermejo, F. (Santiago dse Compostela, Univ. (Spain). Dept. de Quimica Analitica)

1990-01-01

A method for the u.v. determination of cobalt with EDDHA is proposed. Between pH 4-7 the spectrum show and absorption maximum at 255 nm. The effect of amount of reagent, anount of oxidant, acidity, time and temperature have also been studied. Beer's Law is obeyed over the range 0.1 to 2,34 {mu}g Co(III) mL{sup -1} with a minimum photometric error of 3.0%. The molar absortivity was (2.71 {plus minus} 0.02) 10{sup 4} L mol{sup -} {sup 1} cm{sup -1}. The reproducibility, precision, stoichiometry of the complex and interferences have been investigated. (Author)

Uranyl tris-beta-diketonate complexes

International Nuclear Information System (INIS)

Sidorenko, G.V.; Adamov, V.M.; Shcherbakova, L.L.; Suglubov, D.N.

1986-01-01

Uranyl tris-pivaloyltrifluoroacetonates (M/IOTA/UO 2 L 3 ; M/IOTA/ = Na, K, Cs, 1/2Ba, NR 4 ; R = C 8 H 17 ) and tris-dipivaloylmethanate (M/IOTA/UO 2 L/IOTA/ 3 , M/IOTA/ = K) have been synthesized for the first time. The compounds were characterized by chemical analysis and IR, NMR, and mass spectra. NaUO 2 L 3 , KUO 2 L 3 , CsUO 2 L 3 and Ba(UO 2 ) 2 L 6 sublime in high vacuum with partial decomposition. Specifically, decomposition gives UL 4 , identified by mass spectrometry. All the tris-complexes except those with outer-sphere NR 4 cation are characterized by an asymmetric structure of the uranyl group, recorded by IR spectroscopy using isotopic substitution of 18 O in uranyl. NMR spectra of the tris-complexes indicate the equivalence of all beta-diketonate groups, i.e., a coordination number of six for uranyl

Trapping of superoxido cobalt and peroxido dicobalt species formed reversibly from CoII and O2.

Science.gov (United States)

Corona, Teresa; Padamati, Sandeep K; Acuña-Parés, Ferran; Duboc, Carole; Browne, Wesley R; Company, Anna

2017-08-22

The formation and spectroscopic characterization of a superoxido cobalt(iii) and a peroxido dicobalt(iii) species formed in the temperature dependent reversible reaction of a cobalt(ii) precursor with O 2 is described. The electronic nature of each species is explored in their reactivity with organic substrates.

Mechanistic Studies of Cobalt-Catalyzed C(sp2)-H Borylation of Five-Membered Heteroarenes with Pinacolborane.

Science.gov (United States)

Obligacion, Jennifer V; Chirik, Paul J

2017-07-07

Studies into the mechanism of cobalt-catalyzed C(sp 2 )-H borylation of five-membered heteroarenes with pinacolborane (HBPin) as the boron source established the catalyst resting state as the trans -cobalt(III) dihydride boryl, ( iPr PNP)Co(H) 2 (BPin) ( iPr PNP = 2,6-( i Pr 2 PCH 2 ) 2 (C 5 H 3 N)), at both low and high substrate conversions. The overall first-order rate law and observation of a normal deuterium kinetic isotope effect on the borylation of benzofuran versus benzofuran-2- d 1 support H 2 reductive elimination from the cobalt(III) dihydride boryl as the turnover-limiting step. These findings stand in contrast to that established previously for the borylation of 2,6-lutidine with the same cobalt precatalyst, where borylation of the 4-position of the pincer occurred faster than the substrate turnover and arene C-H activation by a cobalt(I) boryl is turnover-limiting. Evaluation of the catalytic activity of different cobalt precursors in the C-H borylation of benzofuran with HBPin established that the ligand design principles for C- H borylation depend on the identities of both the arene and the boron reagent used: electron-donating groups improve catalytic activity of the borylation of pyridines and arenes with B 2 Pin 2 , whereas electron-withdrawing groups improve catalytic activity of the borylation of five-membered heteroarenes with HBPin. Catalyst deactivation by P-C bond cleavage from a cobalt(I) hydride was observed in the C-H borylation of arene substrates with C-H bonds that are less acidic than those of five-membered heteroarenes using HBPin and explains the requirement of B 2 Pin 2 to achieve synthetically useful yields with these arene substrates.

Synergistic extraction of Eu(III) with N-phosphorylated bis-ureas and chlorinated cobalt bis(dicarbollide) ion

Czech Academy of Sciences Publication Activity Database

Selucký, P.; Bubeníková, M.; Rais, J.; Grüner, Bohumír; Brusko, V.V.

2013-01-01

Roč. 101, č. 1 (2013), s. 27-31 ISSN 0033-8230 R&D Projects: GA ČR GA104/09/0668 Institutional support: RVO:61388980 Keywords : liquid-liquid extraction * lanthanides * actinides * N-phosphorylated bis-ureas * chlorinated cobalt bis(dicarbollide) ion * high level liquid waste Subject RIV: CA - Inorganic Chemistry Impact factor: 1.411, year: 2013

Solvent extractions applications to hydrometallurgy. Pt.III: Nickel, cobalt, manganese and ocean nodules

International Nuclear Information System (INIS)

Amer, S.

1981-01-01

The main applications of solvent extraction to the hydrometallurgy of nickel, cobalt, manganese and manganese rich ocean nodules, which also contain nickel, cooper and cobalt, are exposed. A short description of the processes with commercial applications is made. (author)

Moessbauer spectroscopic studies of the chemical effects associated with 57Co(electron capture)57Fe decay in tris-β-diketonatocobalt(III) compounds

International Nuclear Information System (INIS)

Sakai, Yoichi; Endo, Kazutoyo; Sano, Hirotoshi

1980-01-01

Magnetic hyperfine structures (hfs) were found in the absorption Moessbauer spectra at 78 K of a paramagnetic iron(III) complex diluted in a diamagnetic cobalt(III) or aluminium(III) complex such as 57 Fe(acac) 3 in Co(acac) 3 , 57 Fe(oxin) 3 in Al(oxin) 3 , and 57 Fe(dbm) 3 in Co(dbm) 3 (acac=acetylacetonato, oxin=8-quinolinolato, and dbm=dibenzoylmethanato), showing that the magnetic hfs is caused by the spin-spin relaxation through the surrounding diamagnetic species. In the emission Moessbauer experiments, magnetic hfs was observed at 78 K in 57 Co-labelled Co(dbm) 3 , Co(oxin) 3 , and polystyrene-diluted Co(acac) 3 , while it was not observed in 57 Co-labelled Co(acac) 3 and Co(dpm) 3 (dpm=dipivaloylmethanato). The former possess pi -conjugated systems to a greater extent than the latter, either in the ligands or in the vicinity of the 57 Co-labelled Co(III) species. These results were explained in terms of the radiolytic stabilities of the matrices as well as those of 57 Co-labelled compounds by showing that the paramagnetic radicals produced in a diamagnetic matrix quench the magnetic hfs because of the increased spin-spin interaction, as a consequence of the local radiolysis by EC-decay. (author)

Temperature dependent viscosity of cobalt ferrite / ethylene glycol ferrofluids

Science.gov (United States)

Kharat, Prashant B.; Somvanshi, Sandeep B.; Kounsalye, Jitendra S.; Deshmukh, Suraj S.; Khirade, Pankaj P.; Jadhav, K. M.

2018-04-01

In the present work, cobalt ferrite / ethylene glycol ferrofluid is prepared in 0 to 1 (in the step of 0.2) volume fraction of cobalt ferrite nanoparticles synthesized by co-precipitation method. The XRD results confirmed the formation of single phase spinel structure. The Raman spectra have been deconvoluted into individual Lorentzian peaks. Cobalt ferrite has cubic spinel structure with Fd3m space group. FT-IR spectra consist of two major absorption bands, first at about 586 cm-1 (υ1) and second at about 392 cm-1 (υ2). These absorption bands confirm the formation of spinel-structured cobalt ferrite. Brookfield DV-III viscometer and programmable temperature-controlled bath was used to study the relationship between viscosity and temperature. Viscosity behavior with respect to temperature has been studied and it is revealed that the viscosity of cobalt ferrite / ethylene glycol ferrofluids increases with an increase in volume fraction of cobalt ferrite. The viscosity of the present ferrofluid was found to decrease with increase in temperature.

Feasibility Study for Cobalt Bundle Loading to CANDU Reactor Core

International Nuclear Information System (INIS)

Park, Donghwan; Kim, Youngae; Kim, Sungmin

2016-01-01

CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor’s full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly. But the neutron absorption characteristic of cobalt bundle is too high, so optimizing design study is needed in the future

Feasibility Study for Cobalt Bundle Loading to CANDU Reactor Core

Energy Technology Data Exchange (ETDEWEB)

Park, Donghwan; Kim, Youngae; Kim, Sungmin [KHNP Central Research Institute, Daejeon (Korea, Republic of)

2016-10-15

CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor’s full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly. But the neutron absorption characteristic of cobalt bundle is too high, so optimizing design study is needed in the future.

Synthesis and magneto-structural studies on a new family of carbonato bridged 3d-4f complexes featuring a [CoLn(CO3)] (Ln = La, Gd, Tb, Dy and Ho) core: slow magnetic relaxation displayed by the cobalt(ii)-dysprosium(iii) analogue.

Science.gov (United States)

Majee, Mithun Chandra; Towsif Abtab, Sk Md; Mondal, Dhrubajyoti; Maity, Manoranjan; Weselski, Marek; Witwicki, Maciej; Bieńko, Alina; Antkowiak, Michał; Kamieniarz, Grzegorz; Chaudhury, Muktimoy

2018-03-06

A new family of [3 + 3] hexanuclear 3d-4f complexes [(μ 3 -CO 3 ){Co II Ln III L(μ 3 -OH)(OH 2 )} 3 ]-(ClO 4 )·mC 2 H 5 OH·nH 2 O (1-5) [Ln = La (1), Gd (2), Tb (3), Dy (4), and Ho (5)] have been prepared in moderate to high yields (62-78%) following a self-assembly reaction between the ligand 6,6',6''-(nitrilotris(methylene))tris-(2-methoxy-4-methylphenol) (H 3 L), Co(OAc) 2 ·4H 2 O and the lanthanide ion precursors in the mandatory presence of tetrabutylammonium hydroxide. During the reaction, atmospheric carbon dioxide is fixed in the product molecule as a bridging carbonato ligand which connects all the three lanthanide centers of this molecular assembly through a rare η 2 :η 2 :η 2 -μ 3 mode of bridging as revealed from X-ray crystallography. The metal centers in all these compounds, except the Gd III analogue (2), are coupled in antiferromagnetic manner while the nature of coupling in the CoGd complex is ferromagnetic. DFT calculations revealed that this ferromagnetic interaction occurs most likely by the Co II -Gd III superexchange, mediated via the bridging oxygen atoms. Only the Co II -Dy III compound (4) displayed a slow relaxation of the magnetization at a very low temperature as established by AC susceptibility measurements. The data provides an estimation of the activation energy U/k B = 9.2 K and the relaxation time constant τ 0 = 1.0 × 10 -7 s.

Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

International Nuclear Information System (INIS)

Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho

2016-01-01

Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic

Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

Energy Technology Data Exchange (ETDEWEB)

Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho [Dept. of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan (Korea, Republic of)

2016-12-15

Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic.

Tris(O-cyclohexyl dithiocarbonato-κSantimony(III

Directory of Open Access Journals (Sweden)

Wenkuan Li

2009-01-01

Full Text Available In the molecule of the title compound, [Sb(C7H11OS23], the antimony(III is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination.

Thermodynamic and kinetic studies of the equilibration reaction between the sulfur and carbon bonded forms of a cobalt(III) complex with the ligands 1,4,7-triazycyclononane and 1,4-diaza-7-thiacyclodecane

DEFF Research Database (Denmark)

Song, Y.S.; Becker, J.; Kofod, Pauli

1996-01-01

The new cyclic thioether 1,4-diaza-7-thiacyclodecane, dathicd, has been synthesized and used for the prepn. of the sulfur- and carbon-bonded cobalt(III) complexes: [Co(tacn)(S-dathicd)]Cl3.5H2O and [Co(tacn)(C-dathicd)](ClO4)2 (tacn, 1,4,7-triazacyclononane; C-dathicd, 1,4-diamino-7-thiacyclodecan......-sulfur complex to form the alkyl complex gave 100% loss of deuterium. It is concluded that the labile methylene proton is bound to the carbon atom which in the alkyl complex is bound to cobalt(III). From the kinetic data it is estd. that the carbanion reacts with water 270 times faster than it is captured...

A rational route to SCM materials based on a 1-D cobalt selenocyanato coordination polymer.

Science.gov (United States)

Boeckmann, Jan; Näther, Christian

2011-07-07

Thermal annealing of a discrete complex with terminal SeCN anions and monodentate coligands enforces the formation of a 1D cobalt selenocyanato coordination polymer that shows slow relaxation of the magnetization. Therefore, this approach offers a rational route to 1D materials that might show single chain magnetic behaviour. This journal is © The Royal Society of Chemistry 2011

Aquachlorido{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilodimethylidyne]diphenolato-κ2O1,N,N′,O1′}cobalt(III monohydrate

Directory of Open Access Journals (Sweden)

Jianxin Xing

2009-04-01

Full Text Available The title compound, [Co(C18H18N2O4Cl(H2O]·H2O, contains a distorted octahedral cobalt(III complex with a 6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilodimethylidyne]diphenolate ligand, a chloride and an aqua ligand, and also a disordered water solvent molecule (half-occupancy. The CoIII ion is coordinated in an N2O3Cl manner. Weak O—H...O hydrogen bonds may help to stabilize the crystal packing.

Vapor pressures of dimethylcadmium, trimethylbismuth, and tris(dimethylamino)antimony

Czech Academy of Sciences Publication Activity Database

Morávek, Pavel; Fulem, Michal; Pangrác, Jiří; Hulicius, Eduard; Růžička, K.

2013-01-01

Roč. 360, Dec (2013), s. 106-110 ISSN 0378-3812 R&D Projects: GA ČR GA13-15286S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : vapor pressure * dimethylcadmium * trimethylbismuth * tris(dimethylamino)antimony * sublimation and vaporization enthalpy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.241, year: 2013

Cobalt

Science.gov (United States)

Slack, John F.; Kimball, Bryn E.; Shedd, Kim B.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Cobalt is a silvery gray metal that has diverse uses based on certain key properties, including ferromagnetism, hardness and wear-resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, multiple valences, and production of intense blue colors when combined with silica. Cobalt is used mostly in cathodes in rechargeable batteries and in superalloys for turbine engines in jet aircraft. Annual global cobalt consumption was approximately 75,000 metric tons in 2011; China, Japan, and the United States (in order of consumption amount) were the top three cobalt-consuming countries. In 2011, approximately 109,000 metric tons of recoverable cobalt was produced in ores, concentrates, and intermediate products from cobalt, copper, nickel, platinum-group-element (PGE), and zinc operations. The Democratic Republic of the Congo (Congo [Kinshasa]) was the principal source of mined cobalt globally (55 percent). The United States produced a negligible amount of byproduct cobalt as an intermediate product from a PGE mining and refining operation in southeastern Montana; no U.S. production was from mines in which cobalt was the principal commodity. China was the leading refiner of cobalt, and much of its production came from cobalt ores, concentrates, and partially refined materials imported from Congo (Kinshasa).The mineralogy of cobalt deposits is diverse and includes both primary (hypogene) and secondary (supergene) phases. Principal terrestrial (land-based) deposit types, which represent most of world’s cobalt mine production, include primary magmatic Ni-Cu(-Co-PGE) sulfides, primary and secondary stratiform sediment-hosted Cu-Co sulfides and oxides, and secondary Ni-Co laterites. Seven additional terrestrial deposit types are described in this chapter. The total terrestrial cobalt resource (reserves plus other resources) plus past production, where available, is calculated to be 25.5 million metric tons. Additional resources of

Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System.

Science.gov (United States)

Venkatesan, Shanmuganathan; Liu, I-Ping; Chen, Li-Tung; Hou, Yi-Chen; Li, Chiao-Wei; Lee, Yuh-Lang

2016-09-21

Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions.

Self-Assembled Hierarchical Formation of Conjugated 3D Cobalt Oxide Nanobead-CNT-Graphene Nanostructure Using Microwaves for High-Performance Supercapacitor Electrode.

Science.gov (United States)

Kumar, Rajesh; Singh, Rajesh Kumar; Dubey, Pawan Kumar; Singh, Dinesh Pratap; Yadav, Ram Manohar

2015-07-15

Here we report the electrochemical performance of a interesting three-dimensional (3D) structures comprised of zero-dimensional (0D) cobalt oxide nanobeads, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, stacked hierarchically. We have synthesized 3D self-assembled hierarchical nanostructure comprised of cobalt oxide nanobeads (Co-nb), carbon nanotubes (CNTs), and graphene nanosheets (GNSs) for high-performance supercapacitor electrode application. This 3D self-assembled hierarchical nanostructure Co3O4 nanobeads-CNTs-GNSs (3D:Co-nb@CG) is grown at a large scale (gram) through simple, facile, and ultrafast microwave irradiation (MWI). In 3D:Co-nb@CG nanostructure, Co3O4 nanobeads are attached to the CNT surfaces grown on GNSs. Our ultrafast, one-step approach not only renders simultaneous growth of cobalt oxide and CNTs on graphene nanosheets but also institutes the intrinsic dispersion of carbon nanotubes and cobalt oxide within a highly conductive scaffold. The 3D:Co-nb@CG electrode shows better electrochemical performance with a maximum specific capacitance of 600 F/g at the charge/discharge current density of 0.7A/g in KOH electrolyte, which is 1.56 times higher than that of Co3O4-decorated graphene (Co-np@G) nanostructure. This electrode also shows a long cyclic life, excellent rate capability, and high specific capacitance. It also shows high stability after few cycles (550 cycles) and exhibits high capacitance retention behavior. It was observed that the supercapacitor retained 94.5% of its initial capacitance even after 5000 cycles, indicating its excellent cyclic stability. The synergistic effect of the 3D:Co-nb@CG appears to contribute to the enhanced electrochemical performances.

Interaction mode between methylene blue-Sm(III) complex and ...

African Journals Online (AJOL)

Spectroscopic and viscosity methods were applied to investigate the interaction between methylene blue (MB)-Sm(III) complex and herring sperm DNA by using acridine orange as a spectral probe in Tris-HCl buffer (pH 7.40). By means of molar ratio method, the binding ratios between MB-Sm(III)and DNA were determined ...

Cobalt(2) and nickel(2) tris-acetylacetonates with alkali metal cations in outer sphere

International Nuclear Information System (INIS)

Steblyanko, A.Yu.; Grigor'ev, A.N.; Martynenko, L.I.

1996-01-01

Anhydrous tris-acetylacetonates of Co(2) and Ni(2) with alkali metal cations in outer sphere were synthesized and investigated by different physicochemical methods. Chemical analysis and IR-spectroscopy show, that complex composition corresponds to the formula Eh[MA 3 ] (where Eh + - Li + , Na + , K + , Rb + , Cs + ; M - Co(2), Ni(2); A - - acetyacetonate-ion). Eh[MA 3 ] heating in vacuum leads to transition of volatile Co(2) and Ni(2) acetylacetonates to gaseous phase. The data of photoelectron spectroscopy and vacuum sublimation show, that Li[MA 3 ] is transformed to gaseous phase congruently and only partially dissociates to EhA and MA 2 . Li[MA 3 ] and Cs[MA 3 ] are characterized by the lowest thermal stability at atmospheric pressure. Low stability of Li[MA 3 ] is related with detachment of one of A - radical from [MA 3 ] complex anion by Li + cation under conditions, when LiA and Li[MA 3 ] are volatile. 11 refs.; 2 figs.; 3 tabs

HAEM SYNTHASE AND COBALT PORPHYRIN SYNTHASE IN VARIOUS MICRO-ORGANISMS.

Science.gov (United States)

PORRA, R J; ROSS, B D

1965-03-01

1. The preparation of a crude extract of Clostridium tetanomorphum containing cobalt porphyrin synthase but little haem-synthase activity is described. 2. The properties of cobalt porphyrin synthase in the clostridial extracts is compared with the properties of a haem synthase present in crude extracts of the yeast Torulopsis utilis. 3. Cobalt porphyrin synthase in extracts of C. tetanomorphum inserts Co(2+) ions into the following dicarboxylic porphyrins in descending order of rate of insertion: meso-, deutero- and proto-porphyrins. Esterification renders meso- and deutero-porphyrins inactive as substrates. Neither the tetracarboxylic (coproporphyrin III) nor the octacarboxylic (uroporphyrin III) compounds are converted into cobalt porphyrins by the extract, but the non-enzymic incorporation of Co(2+) ions into these two porphyrins is rapid. These extracts are unable to insert Mn(2+), Zn(2+), Mg(2+) or Cu(2+) ions into mesoporphyrin. 4. Crude extracts of T. utilis readily insert both Co(2+) and Fe(2+) ions into deutero-, meso, and proto-porphyrins. Unlike the extracts of C. tetanomorphum, these preparations catalyse the insertion of Co(2+) ions into deuteroporphyrin more rapidly than into mesoporphyrin. This parallels the formation of haems by the T. utilis extract. 5. Cobalt porphyrin synthase is present in the particulate fraction of the extracts of C. tetanomorphum but requires a heat-stable factor present in the soluble fraction. This soluble factor can be replaced by GSH. 6. Cobalt porphyrin synthase in the clostridial extract is inhibited by iodoacetamide and to a smaller extent by p-chloromercuribenzoate and N-ethylmaleimide. The haem synthases of T. utilis and Micrococcus denitrificans are also inhibited by various thiol reagents.

Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

Science.gov (United States)

AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

2007-07-01

Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

Contribution to the study of the chemical consequences of the (n, {gamma}) reaction in solid Co(3) tris-acetylacetone; Contribution a l'etude des consequences chimiques de la reaction (n, {gamma}) dans le tris-acetylacetonate de cobalt (3)

Energy Technology Data Exchange (ETDEWEB)

Magnane Machado, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-07-01

The fragmentation and annealing of thermal neutron irradiated Co(III) tris-acetylacetone was investigated using the thin layer chromatographic technique (silica-gel 1 mm thickness). Low temperature irradiations (0 C - -72 C and -180 C) lead to {sup 60}Co retentions as low as (1,1 {+-} 0,2) per cent. Annealing by linear temperature programming at different heating rates has shown the existence of eight reactions. The influences of pile dose and of gases (air and helium) as well as of thermal decomposition on the annealing processes were confirmed. A temperature and dose dependent effect was found out for the retentions of the {sup 60m}Co - {sup 60}Co isomers. (author) [French] On a etudie par chromatographie en couches minces (silicagel 1 mm), les phenomenes de fragmentation et de recuit sur l'acetylacetonate de Co(III) irradie aux neutrons thermiques. La valeur minimale de la retention observee pour des irradiations a basse temperature (0 C, -72 C, -180 C) se situe a (1,1 {+-} 0,2) pour cent. Le recuit thermique, par montee lineaire de la temperature a differentes vitesses de chauffage, montre l'existence de huit reactions. On confirme, de plus, l'influence sur les processus de recuit de la dose recue en pile, de l'atmosphere dans laquelle l'echantillon se trouve (air et helium) ainsi que de la decomposition thermique. Cette dependance de la temperature et de la dose est prouvee par les valeurs des retentions mesurees sur les isomeres {sup 60m}Co - {sup 60}Co. (auteur)

Tuning size and catalytic activity of nano-clusters of cobalt oxide

Indian Academy of Sciences (India)

Unknown

oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sul- .... Co(NO3)2 + Na2CO3 → CoCO3 + 2NaNO3,. CoCO3. ∆. → ∆ CoO + CO2,. CoO → (in air and heating) Co3O4. In method III, cobalt nitrate, sodium dodecyl sul- .... The conversion of cyclohexane on the current po-.

Extension of the analysis of the three lowest configurations in the third spectrum of cobalt (Co III)

International Nuclear Information System (INIS)

Raassen, A.J.J.; Orti Ortin, S.

1984-01-01

The emission spectrum of cobalt has been observed in the wavelength region 450-3100 A using a hollow cathode as well as a sliding spark lightsource. In this region 680 lines belonging to transitions from the 3d 6 4p configuration to the 3d 7 configuration and 630 lines belonging to transitions from 3d 6 4p to 3d 6 4s are now classified. All 19 levels of the 3d 7 configuration have been established while in 3d 6 4s and 3d 6 4p 59(64) and 178(180) levels have been determined respectively. The numbers in parentheses give the total number of theoretically possible levels in the two configurations. Parametric fits to the levels of the three configurations as well as eigenvector compositions of the levels are presented. The parameter values are compared to Hartree-Fock predictions. (orig.)

Possible pore size effects on the state of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas and their temperature dependence.

Science.gov (United States)

Tagaya, Motohiro; Ogawa, Makoto

2008-12-07

The states of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas with different pore sizes (2.5, 3.1 and 5.0 nm) were investigated. Alq3 was successfully occluded into the mesoporous silicas from solution and the adsorbed amount of Alq3 per BET surface area was effectively controlled by changing the added amount Alq3 to the solution. The state of Alq3 in the mesopore varied depending on the pore size as well as the adsorbed amount of Alq3 as revealed by variation of the photoluminescence spectra. The luminescence of the adsorbed Alq3 was found to be temperature-dependent, indicating the mobility of the adsorbed Alq3 to temperature variations. The temperature-dependence also depended on the pore size. The guest-guest interactions between Alq3 molecules as well as the host-guest interactions between Alq3 and the mesopore were controlled by the pore size.

Thermophysical property characterization of tris(hydroxymethyl)aminomethane

International Nuclear Information System (INIS)

Soriano, Allan N.; Cabahug, Denise Irene V.; Li Menghui

2011-01-01

In this present work, a thermophysical property characterization of aqueous solution of tris(hydroxymethyl)aminomethane (TRIS), a biological buffer, was done. The investigated properties were refractive index (n), density (ρ), and electrolytic conductivity (κ). These properties were measured for temperatures up to 353.15 K (at normal atmospheric condition) and for the entire composition range where TRIS is still soluble in water. The measured properties were reported as functions of temperature and composition. A modified form of the Vogel-Tamman-Fulcher equation which leads to an Arrhenius-type asymptotic exponential function was used to generally correlate the temperature and compositional dependence of the considered properties and satisfactory results were obtained.

Synthesis, structures and urease inhibitory activity of cobalt(III) complexes with Schiff bases.

Science.gov (United States)

Jing, Changling; Wang, Cunfang; Yan, Kai; Zhao, Kedong; Sheng, Guihua; Qu, Dan; Niu, Fang; Zhu, Hailiang; You, Zhonglu

2016-01-15

A series of new cobalt(III) complexes were prepared. They are [CoL(1)(py)3]·NO3 (1), [CoL(2)(bipy)(N3)]·CH3OH (2), [CoL(3)(HL(3))(N3)]·NO3 (3), and [CoL(4)(MeOH)(N3)] (4), where L(1), L(2), L(3) and L(4) are the deprotonated form of N'-(2-hydroxy-5-methoxybenzylidene)-3-methylbenzohydrazide, N'-(2-hydroxybenzylidene)-3-hydroxylbenzohydrazide, 2-[(2-dimethylaminoethylimino)methyl]-4-methylphenol, and N,N'-bis(5-methylsalicylidene)-o-phenylenediamine, respectively, py is pyridine, and bipy is 2,2'-bipyridine. The complexes were characterized by infrared and UV-Vis spectra, and single crystal X-ray diffraction. The Co atoms in the complexes are in octahedral coordination. Complexes 1 and 4 show effective urease inhibitory activities, with IC50 values of 4.27 and 0.35 μmol L(-1), respectively. Complex 2 has medium activity against urease, with IC50 value of 68.7 μmol L(-1). While complex 3 has no activity against urease. Molecular docking study of the complexes with Helicobacter pylori urease was performed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electroremovable Traceless Hydrazides for Cobalt-Catalyzed Electro-Oxidative C-H/N-H Activation with Internal Alkynes.

Science.gov (United States)

Mei, Ruhuai; Sauermann, Nicolas; Oliveira, João C A; Ackermann, Lutz

2018-06-27

Electrochemical oxidative C-H/N-H activations have been accomplished with a versatile cobalt catalyst in terms of [4 + 2] annulations of internal alkynes. The electro-oxidative C-H activation manifold proved viable with an undivided cell setup under exceedingly mild reaction conditions at room temperature using earth-abundant cobalt catalysts. The electrochemical cobalt catalysis prevents the use of transition metal oxidants in C-H activation catalysis, generating H 2 as the sole byproduct. Detailed mechanistic studies provided strong support for a facile C-H cobaltation by an initially formed cobalt(III) catalyst. The subsequent alkyne migratory insertion was interrogated by mass spectrometry and DFT calculations, providing strong support for a facile C-H activation and the formation of a key seven-membered cobalta(III) cycle in a regioselective fashion. Key to success for the unprecedented use of internal alkynes in electrochemical C-H/N-H activations was represented by the use of N-2-pyridylhydrazides, for which we developed a traceless electrocleavage strategy by electroreductive samarium catalysis at room temperature.

Construction of Pyrrolo[1,2-a]indoles via Cobalt(III)-Catalyzed Enaminylation of 1-(Pyrimidin-2-yl)-1H-indoles with Ketenimines and Subsequent Base-Promoted Cyclization.

Science.gov (United States)

Zhou, Xiaorong; Fan, Zili; Zhang, Zhiyin; Lu, Ping; Wang, Yanguang

2016-09-16

A cobalt(III)-catalyzed cross-coupling reaction of 1-(pyrimidin-2-yl)-1H-indoles with ketenimines is reported. The reaction provided 2-enaminylated indole derivatives in moderate to excellent yields with a broad substrate scope. The prepared 2-enaminylated indoles could be conveniently converted into pyrrolo[1,2-a]indoles, which are an important class of compounds in medicinal chemistry.

Operationally defined species characterization and bioaccessibility evaluation of cobalt, copper and selenium in Cape gooseberry (Physalis Peruviana L.) by SEC-ICP MS.

Science.gov (United States)

Wojcieszek, Justyna; Ruzik, Lena

2016-03-01

Physalis peruviana could attract great interest because of its nutritional and industrial properties. It is an excellent source of vitamins, minerals, essential fatty acids and carotenoids. Physalis Peruviana is also known to have a positive impact on human health. Unfortunately, still little is known about trace elements present in Physalis Peruviana and their forms available for the human body. Thus, the aim of this study was to estimate bioaccessibility and characterization of species of cobalt, copper and selenium in Physalis Peruviana fruits. Total and extractable contents of elements were determined by mass spectrometer with inductively coupled plasma (ICP MS). In order to separate the different types of metal complexes Physalis peruviana fruits were treated with the following solvents: Tris-HCl (pH 7.4), sodium dodecyl sulfate (SDS) (pH 7.4) and ammonium acetate (pH 5.5). The best efficiency of extraction of: cobalt was obtained for ammonium acetate (56%) and Tris-HCl (60%); for copper was obtained for SDS (66%), for selenium the best extraction efficiency was obtained after extraction with SDS (48%). To obtain information about bioaccessibility of investigated elements, enzymatic extraction based on in vitro simulation of gastric (pepsin) and intestinal (pancreatin) digestion was performed. For copper and selenium the simulation of gastric digestion leads to the extraction yield above 90%, while both steps of digestion method were necessary to obtain satisfactory extraction yield in the case of cobalt. Size exclusion chromatography (SEC) coupled to on-line ICP MS detection was used to investigate collected metal species. The main fraction of metal compounds was found in the 17 kDa region. Cobalt and copper create complexes mostly with compounds extracted by means of ammonium acetate and SDS, respectively. Cobalt, copper and selenium were found to be highly bioaccessible from Physalis Peruviana. Investigation of available standards of cobalt and selenium

Synthesis of homochiral tris-indanyl molecular rods

DEFF Research Database (Denmark)

Kjeldsen, Niels Due; Funder, Erik Daa; Gothelf, Kurt Vesterager

2014-01-01

Homochiral tris-indanyl molecular rods designed for supramolecular surface self-assembly were synthesized. The chiral indanol moiety was constructed via a Ti-mediated alkyne trimerization. Further manipulations resulted in a homochiral indanol monomer. This was employed as the precursor for succe...... for successive Sonogashira and Ohira-Bestman reactions towards the homochiral tris-indanyl molecular rods. The molecular rods will be applied for scanning tunnelling microscopy studies of their surface self-assembly and chirality.......Homochiral tris-indanyl molecular rods designed for supramolecular surface self-assembly were synthesized. The chiral indanol moiety was constructed via a Ti-mediated alkyne trimerization. Further manipulations resulted in a homochiral indanol monomer. This was employed as the precursor...

Kinetics and mechanism of the conversion of a coordinated thiol to a coordinated disulfide by the one-equivalent oxidants neptunium(VI) and cobalt(III) in aqueous perchloric acid

International Nuclear Information System (INIS)

Woods, M.; Karbwang, J.; Sullivan, J.C.; Deutsch, E.

1976-01-01

Reaction of excess (2-mercaptoethylamine-N,S)bis(ethylenediamine)cobalt(III), I, with the 1-equiv oxidant Np(VI) (or Co 3+ (aq)) in aqueous perchloric acid media is shown to lead to (2-aminoethyl-N 2-ammonioethyl disulfide-S 1 ) bis(ethylenediamine)cobalt(III), II, according to the stoichiometry 5H + + 2I + Np(VI) → II + Co 2+ (aq) + Np(V) + 2enH 2 2+ . This reaction follows the rate law -d[I]/dt = k'' [I] [oxidant]. For Np(VI) as oxidant k'' is independent of [H + ]; at 25 0 C, μ = 1.00 M (LiClO 4 ), k'' = k 0 = 2842 +- 15 M -1 s -1 , ΔH 0 * = 7.57 +- 0.08 kcal/mol, and ΔS 0 * = -17.4 +- 0.3 eu. For Co 3+ (aq) as oxidant, k'' = k 0 + k/sub -1/[H + ] -1 where the inverse acid path is taken to reflect oxidation by CoOH 2+ (aq); at 25 0 C, μ = 1.00 M (LiClO 4 ), k 0 = 933 +- 32 M -1 s -1 , k/sub -1/ = 1152 +- 22 s -1 , ΔH 0 * = 12.5 +- 0.7 kcal/mol, ΔH*/sub -1/ = 18.0 +- 0.4 kcal/mol, ΔS 0 *= -3.1 +- 2.4 eu, and ΔS*/sub -1/ = 15.8 +- 1.2 eu. It is proposed that the conversion of I to II proceeds by initial 1-equiv oxidation of the coordinated thiol, reaction of the resultant coordinated thiol radical (RS.) with additional I to form a relatively stable radical ion dimer (RSSR. - ), and then internal electron transfer within the dimer to yield Co 2+ (aq) and II which contains a coordinated disulfide. The possible generality of this mechanism and its relevance to biological metal-thiol-disulfide interactions are noted

Production of 203Pb-tris-hydroxymethyl amino methane

International Nuclear Information System (INIS)

Lambrecht, R.M.; Packer, S.; Merrill, J.C.; Atkins, H.L.; Wolf, A.P.; Bradley-Moore, P.R.

1977-01-01

203 Pb-tris complex is injected for use in the detection and localization of tumors. The lead-203 is produced from the deuteron bombardment of a thallium target and chemically separated from the thallium. The tris is added which complexes with the lead-203

Preparation of Chloro Penta Amine Cobalt(III Chloride and Study of Its Influence on the Structural and Some Optical Properties of Polyvinyl Acetate

Directory of Open Access Journals (Sweden)

Nada K. Abbas

2015-01-01

Full Text Available Chloro penta amine cobalt(III cloride [Co(NH35Cl]Cl2 was prepared and then characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The obtained results indicated the formation of orthorhombic [Co(NH35Cl]Cl2 nanoparticles of ≈28.75 nm size. Polymeric films based on polyvinyl acetate (PVAc doped with chloro penta amine cobalt(III cloride [Co(NH35Cl]Cl2 in different weight percent ratios were prepared using the solvent cast technique. The complexation of the additive with the polymer was confirmed by FTIR and SEM studies. The XRD pattern revealed that the amorphousicity of PVAc polymer matrix increased with raising the [Co(NH35Cl]Cl2 content. Parameters such as extinction coefficient, refractive index, real and imaginary parts, and optical conductivity were studied by using the absorbance and measurements from computerized UV-visible spectrophotometer in the spectral range 190–800 nm. This study showed that the optical properties of PVAc were affected by the doping of [Co(NH35Cl]Cl2 where the absorption increased by leveling up [Co(NH35Cl]Cl2 concentration. The nature of electronic transition from valence band to conduction band was determined and the energy band gaps of the composite films samples were estimated by UV-visible spectrum. It was observed that the optical conductivity increased with photon energy and with the increase of [Co(NH35Cl]Cl2 concentration.

Synthesis and characterization ligand tris-(2-thiosalicylamidoethyl)amine and its iron complexes and indium

International Nuclear Information System (INIS)

Guerra-Garcia, Pedro Pablo; Valle Bourrouet, Grettel

2006-01-01

The synthesis of coordination chemistry ligand tris-(2-tiosalicilamidoetil)amine is presented within the framework of study of tripod ligands, the corresponding complexes of iron and indium. Also, its spectroscopic characterization by proton magnetic resonance is showed; so the influence of ligand on a redox active metal and an inactive is compared. Electrochemical methods have been used. The presence of sulfur atoms modifies the redox and magnetic behavior of iron ion (III), as has been found in other similar ligands [es

Redetermination of dicerium(III tris(sulfate tetrahydrate

Directory of Open Access Journals (Sweden)

Xin Xu

2008-01-01

Full Text Available Ce2(SO43(H2O4 was obtained hydrothermally from an aqueous solution of cerium(III oxide, trimethylamine and sulfuric acid. The precision of the structure determination has been significantly improved compared with the previous result [Dereigne (1972. Bull. Soc. Fr. Mineral. Cristallogr. 95, 269–280]. The coordination about the two Ce atoms is achieved by seven and six bridging O atoms from sulfate anions. Each S atom makes four S—O—Ce linkages through bridging O atoms. The coordination sphere of each Ce is completed by two water molecules, which act as terminal ligands.

Lactose and ''tris'' lyoluminescence dosimetry systems and ESR correlation studies

International Nuclear Information System (INIS)

Oommen, I.K.; Nambi, K.S.V.; Sengupta, S.; Rao, T.K.G.; Ravikumar, M.

1989-01-01

Lyoluminescence (LL) dosimeters have been developed using lactose monohydrate (disaccharide) and tris(hydroxymethyl)aminomethane (''Tris'') systems and attempts have been made to understand the LL mechanism through ESR correlation studies. Tris LL dosimeter has a γ-ray sensitivity with a linear response in the absorbed-dose range 0.05-200 Gy (5-2 x 10 4 rad), while the lactose response extends to a higher range from 1 to 10 4 Gy (10 2 -10 6 rad). The LL output of lactose and Tris did not show any appreciable decay for a period of 6 months after irradiation. ESR measurements show that free-radical concentration in both the systems increases with γ-ray dose in the range 10 2 -10 5 Gy. The minimum dose required to measure the radiation-induced ESR signal for Tris is ∼ 500 Gy, the dose at which the LL output saturates, while lactose shows a radiation-induced ESR signal right at the minimum dose where LL could be detected. The estimated spin density on the radical carbon atom is 0.7. ESR signal stabilities of lactose and Tris were also studied. Lactose did not show any appreciable ESR decay for a period of 3 months after irradiation, while, for Tris, one of the radicals showed a decay of 45% for the same period. (author)

Lyoluminescence of tris (hydroxymethyl) aminomethane in gamma dosimetry

International Nuclear Information System (INIS)

Azorin, J.; Gutierrez, A.; Guadarrama, L.

1986-01-01

Gamma dosimetry using lyoluminescence (LL) has advantages over other conventional systems because of its low cost and simplicity of use. Results of the investigation of the LL properties of tris (hydroxymethyl) aminomethane irradiated with 60 Co gamma radiation are presented and compared with the results of the LL of mannose and sucrose. Tris on dissolution in luminol shows a higher LL response than that of mannose and lower than that of sucrose, and has the highest stability of the three systems. The LL response of tris was linear in the range 5 Gy to 1kGy and showed no fading during one week. A comparison with the results of other authors as well as with measurements by ESR techniques are also reported. From these results we conclude that tris (hydroxymethyl) aminomethane on dissolution in luminol provides a LL dosimetric system useful for gamma dosimetry in the radiation processing of foods. (author)

Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

Energy Technology Data Exchange (ETDEWEB)

Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Akhtari, Keivan [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Soltanian, Saied [Department of Physics, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

2013-07-01

Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO{sub 3}){sub 2}, (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic

Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

International Nuclear Information System (INIS)

Hallaj, Rahman; Akhtari, Keivan; Salimi, Abdollah; Soltanian, Saied

2013-01-01

Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO 3 ) 2 , (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H 2 O 2 and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic activity decreased

Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

KAUST Repository

Anderson, Carly E.; Vagin, Sergei I.; Hammann, Markus; Zimmermann, Leander; Rieger, Bernhard

2013-01-01

Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

KAUST Repository

Anderson, Carly E.

2013-09-18

Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

40 CFR 180.415 - Aluminum tris (O-ethylphosphonate); tolerances for residues.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Aluminum tris (O-ethylphosphonate... Tolerances § 180.415 Aluminum tris (O-ethylphosphonate); tolerances for residues. (a) General. Tolerances are established for residues of the fungicide aluminum tris(O-ethylphosphonate) in or on the following food...

Testing of cobalt-free alloys for valve applications using a special test loop

International Nuclear Information System (INIS)

Benhamou, C.

1992-01-01

Considering that use of cobalt alloys should be avoided as far as possible in PWR components, a programme aimed at establishing the performance of cobalt-free alloys has been performed for valve applications, where cobalt alloys are mainly used. Referring to past work, two types of cobalt-free alloys were selected: Ni-Cr-B-Si and Ni-Cr-Fe alloys. Cobalt-free valves' behaviour has been evaluated comparatively with cobalt valves by implementation of a programme in a special PWR test loop. At the issue of the loop test programme, which included endurance, thermal shock and erosion tests, cobalt-free alloys candidate to replace cobalt alloys are proposed in relation with valve type (globe valve and swing check valve). The following was established: (i) Colmonoy 4-26 (Ni-Cr-B-Si alloy) and Cenium Z20 (Ni-Cr-Fe alloy) deposited by plasma arc process were found suitable for use in 3inch swing check valves; (ii) for integral parts acting as guide rings, Nitronic 60 and Cesium Z20/698 were tested successfully; (iii) for small-bore components such as 2inch globe valves, no solution can yet be proposed; introduction of cobalt-free alloys is dependent on the development of automatic advanced arc surfacing techniques applied to small-bore components

The cobalt-60 container scanner

International Nuclear Information System (INIS)

Jigang, A.; Liye, Z.; Yisi, L.; Haifeng, W.; Zhifang, W.; Liqiang, W.; Yuanshi, Z.; Xincheng, X.; Furong, L.; Baozeng, G.; Chunfa, S.

1997-01-01

The Institute of Nuclear Energy Technology (INET) has successfully designed and constructed a container (cargo) scanner, which uses cobalt-60 of 100-300 Ci as radiation source. The following performances of the Cobalt-60 container scanner have been achieved at INET: a) IQI (Image Quality Indicator) - 2.5% behind 100 mm of steel; b) CI (Contrast Indicator) - 0.7% behind 100 mm of steel; c) SP (Steel Penetration) - 240 mm of steel; d) Maximum Dose per Scanning - 0.02mGy; e) Throughput - twenty 40-foot containers per hour. These performances are equal or similar to those of the accelerator scanners. Besides these nice enough inspection properties, the Cobalt-60 scanner possesses many other special features which are better than accelerator scanners: a) cheap price - it will be only or two tenths of the accelerator scanner's; b) low radiation intensity - the radiation protection problem is much easier to solve and a lot of money can be saved on the radiation shielding building; c) much smaller area for installation and operation; d) simple operation and convenient maintenance; e) high reliability and stability. The Cobalt-60 container (or cargo) scanner is satisfied for boundary customs, seaports, airports and railway stations etc. Because of the nice special features said above, it is more suitable to be applied widely. Its high properties and low price will make it have much better application prospects

Preparation of rare earth-cobalt magnet alloy by reduction-diffusion process

International Nuclear Information System (INIS)

Krishnan, T.S.

1980-01-01

Preparation of rare earth-cobalt alloys by reduction-diffusion (R-D) process is described. The process essentially involves mixing of the rare earth oxide and cobalt/cobalt oxide powders in proper proportion and high temperature reduction of the charge in hydrogen atmosphere, followed by aqueous leaching of the reduced mass to yield the alloy powder. Comparison is made of the magnetic properties of the R-D powder with those of the powder prepared by the direct melting (DM) route and it is observed from the reported values for SmCo 5 that the energy product of the R-D powder (approximately 22 MGOe) is only marginally lower than that of the directly melted alloy (approximately 25 MGOe). The paper also includes the results of studies carried out at the Bhabha Atomic Research Centre, Bombay, on the preparation of misch metal-cobalt alloy by the R-D process. (auth.)

3D WO3 /BiVO4 /Cobalt Phosphate Composites Inverse Opal Photoanode for Efficient Photoelectrochemical Water Splitting.

Science.gov (United States)

Zhang, Haifeng; Zhou, Weiwei; Yang, Yaping; Cheng, Chuanwei

2017-04-01

A novel 3D WO 3 /BiVO 4 /cobalt phosphate composite inverse opal is designed for photoeletrochemical (PEC) water splitting, yielding a significantly improved PEC performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Ascorbate on the Cyanide-Scavenging Capability of Cobalt(III) meso-Tetra(4-N-methylpyridyl)porphine Pentaiodide: Deactivation by Reduction?

Science.gov (United States)

Benz, Oscar S; Yuan, Quan; Cronican, Andrea A; Peterson, Jim; Pearce, Linda L

2016-03-21

The Co(III)-containing water-soluble metalloporphyrin cobalt(III) meso-tetra(4-N-methylpyridyl)porphine pentaiodide (Co(III)TMPyP) is a potential cyanide-scavenging agent. The rate of reduction of Co(III)TMPyP by ascorbate is facile enough that conversion to the Co(II)-containing Co(II)TMPyP should occur within minutes at prevailing in vivo levels of the reductant. It follows that any cyanide-decorporating capability of the metalloporphyrin should depend more on the cyanide-binding characteristics of Co(II)TMPyP than those of the administered form, Co(III)TMPyP. Addition of cyanide to buffered aqueous solutions of Co(II)TMPyP (pH 7.4, 25-37 °C) results in quite rapid (k2 = ∼10(3) M(-1) s(-1)) binding/substitution of cyanide anion in the two available axial positions with high affinity (K'β = 10(10) to 10(11)). Electron paramagnetic resonance spectroscopic measurements and cyclic voltammetry indicate that cyanide induces oxidation to the Co(III)-containing dicyano species. The constraints that these observations put on plausible mechanisms for the reaction of Co(II)TMPyP with cyanide are discussed. Experiments in which Co(III)TMPyP and cyanide were added to freshly drawn mouse blood showed the same sequence of reactions (metalloporphyrin reduction → cyanide binding/substitution → reoxidation) to occur. Therefore, in cyanide-scavenging applications with this metalloporphyrin, we should be taking advantage of both the improved rate of ligand substitution at Co(II) compared to that at Co(III) and the increased affinity of Co(III) for anionic ligands compared to that of Co(II). Finally, using an established sublethal mouse model for cyanide intoxication, Co(III)TMPyP, administered either 5 min before (prophylaxis) or 1 min after the toxicant, is shown to have very significant antidotal capability. Possible explanations for the results of a previous contradictory study, which failed to find any prophylactic effect of Co(III)TMPyP toward cyanide intoxication, are

Study of the point defects formed in cobalt by electron bombardment; Etude des defauts ponctuels crees par bombardement electronique dans le cobalt

Energy Technology Data Exchange (ETDEWEB)

Sulpice, G [Commissariat a l' Energie Atomique, 38 - Grenoble (France). Centre d' Etudes Nucleaires

1968-12-01

A study of the point defects formed in cobalt by electron bombardment is presented. The results are compared with those previously obtained for two other ferromagnetic metals of different structure, iron and nickel. In the first part we give a review of the literature concerning the creation of point defects, their contribution to resistivity and their annihilation mode in the three structure types. We then describe the experimental techniques adapted, in particular the study of the resistivity increase during a linear temperature rise. Our investigations concern the following, essential points : the observation of the successive annihilation stages of the point defects formed in pure cobalt, a study of the variations with respect to the doses and energy of the incident particles, and the determination of the annealing kinetics and the corresponding activation energies. The results are finally compared with the various models of point defect annihilation proposed for other metals: none of these interpretations is in perfect agreement with our results. In the case of cobalt we are thus led to modify the model proposed by our laboratory for iron an nickel. The difference between these three metals is explained by the anisotropic character of the cobalt matrix. (author) [French] Nous presentons une etude des defauts ponctuels crees par bombardement electronique dans le cobalt et comparons nos resultats a ceux obtenus precedemment dans deux autres metaux ferromagnetiques de structure differente, le fer et le nickel. Dans une premiere partie nous faisons une mise au point bibliographique comparee sur la creation des defauts, leur contribution a la resistivite et leur mode d'annihilation dans les trois types de structure. Nous decrivons ensuite les techniques experimentales mises au point, en particulier l'etude du revenu de la resistivite au cours d'une montee lineaire de temperature. Au cours de ce travail, nous avons mis en evidence les stades successifs d

Potassium bis(carbonato-O,O')(ethylenediamine-N,N')cobaltate(III) monohydrate at 173 K.

Science.gov (United States)

Belai, N; Dickman, M H; Pope, M T

2001-07-01

The title salt, K[Co(C2H8N2)(CO3)2].H2O, consists of a distorted octahedral cobalt complex anion and a seven-coordinate potassium cation. Both metal atoms have crystallographic twofold symmetry, one C2 axis passing through the Co atom and C--C bond, and another along a short K--O (water) bond of 2.600 A (corrected for libration). The carbonate is bidentate to both cobalt and potassium and the water forms a hydrogen bond to a carbonate O atom.

Syntheses, Characterization, Resolution, and Biological Studies of Coordination Compounds of Aspartic Acid and Glycine

Science.gov (United States)

Akinkunmi, Ezekiel; Ojo, Isaac; Adebajo, Clement; Isabirye, David

2017-01-01

Enantiomerically enriched coordination compounds of aspartic acid and racemic mixtures of coordination compounds of glycine metal-ligand ratio 1 : 3 were synthesized and characterized using infrared and UV-Vis spectrophotometric techniques and magnetic susceptibility measurements. Five of the complexes were resolved using (+)-cis-dichlorobis(ethylenediamine)cobalt(III) chloride, (+)-bis(glycinato)(1,10-phenanthroline)cobalt(III) chloride, and (+)-tris(1,10-phenanthroline)nickel(II) chloride as resolving agents. The antimicrobial and cytotoxic activities of these complexes were then determined. The results obtained indicated that aspartic acid and glycine coordinated in a bidentate fashion. The enantiomeric purity of the compounds was in the range of 22.10–32.10%, with (+)-cis-dichlorobis(ethylenediamine)cobalt(III) complex as the more efficient resolving agent. The resolved complexes exhibited better activity in some cases compared to the parent complexes for both biological activities. It was therefore inferred that although the increase in the lipophilicity of the complexes may assist in the permeability of the complexes through the cell membrane of the pathogens, the enantiomeric purity of the complexes is also of importance in their activity as antimicrobial and cytotoxic agents. PMID:28293149

DDT performance of energetic cobalt coordination compounds. [Dozen of compounds similar to 2-(5-cyanotetrazolato)pentaaminecobalt perchlorate, trinitrotriamine cobalt, dinitrobis(ethylenediamine) cobalt perchlorate

Energy Technology Data Exchange (ETDEWEB)

Lieberman, M.L.; Fleming, W.

1986-01-01

The compound 2-(5-cyanotetrazolato)pentaamminecobalt(III) perchlorate (CP) has been utilized in low-voltage detonators because it reliably undergoes deflagration-to-detonation transition (DDT). In the present investigation, we have compared the performance of over a dozen similar compounds. These compounds all have cobalt as the coordinating metal, most are ammine complexes, and all except one incorporate the perchlorate anion as an oxidizer. Chemical factors such as fuel-to-oxidizer ratio, trigger group, and organic content have been varied. 18 refs., 7 figs., 2 tabs.

Field Effect Devices Sensitive to CO at Room Temperature

Directory of Open Access Journals (Sweden)

Ricardo ARAG?N

2014-10-01

Full Text Available [5,10,15-Tris(2,6-dichlorophenylcorrolate] cobalt(III was used to chemisorb CO selectively, on the gap-gate of MOS capacitors and the state of charge monitored by voltage shifts of the photocurrent induced by pulsed illumination under constant D. C. bias, proportionally to CO concentration in air. Negative chemically induced charges at room temperature induce positive responses above and negative shifts below the threshold voltage, conforming to acceptor behavior, and the dynamic range (125 ppm is limited by the silicon doping concentration. The linear proportionality between CO concentration and surface charge (6.46[ppm.m2.µC-1] corresponds to the low concentration limit of the Langmuir isotherm. Sluggish CO desorption can be compensated by photo stimulation at 395 nm.

Comparison and analysis of zinc and cobalt-based systems as catalytic entities for the hydration of carbon dioxide.

Directory of Open Access Journals (Sweden)

Edmond Y Lau

Full Text Available In nature, the zinc metalloenzyme carbonic anhydrase II (CAII efficiently catalyzes the conversion of carbon dioxide (CO2 to bicarbonate under physiological conditions. Many research efforts have been directed towards the development of small molecule mimetics that can facilitate this process and thus have a beneficial environmental impact, but these efforts have met very limited success. Herein, we undertook quantum mechanical calculations of four mimetics, 1,5,9-triazacyclododedacane, 1,4,7,10-tetraazacyclododedacane, tris(4,5-dimethyl-2-imidazolylphosphine, and tris(2-benzimidazolylmethylamine, in their complexed form either with the Zn(2+ or the Co(2+ ion and studied their reaction coordinate for CO2 hydration. These calculations demonstrated that the ability of the complex to maintain a tetrahedral geometry and bind bicarbonate in a unidentate manner were vital for the hydration reaction to proceed favorably. Furthermore, these calculations show that the catalytic activity of the examined zinc complexes was insensitive to coordination states for zinc, while coordination states above four were found to have an unfavorable effect on product release for the cobalt counterparts.

Determination of stability constants of aminoglycoside antibiotics with their metal complexes

Science.gov (United States)

Tiwow, Vanny M. A.

2014-03-01

One group of aminoglycoside antibiotics contains aminosugars. The aminosugar neomycin B with its derivate product neamine (2-Deoxy-4-0-(2,6-diamino-2,6-dideoxy-α-D-glucopyranosyl)-D-Streptamine) was identified as a free ligands and metal complexes. In particular, the stability constants of metal complexes by potentiometric titration techniques were investigated. Our previous study had determined the acid dissociation constants of these aminosugars with few metal complexes in fair depth. In this work, the complexation of two pyridine-containing amino alcohols and an amino sugar (neamine) have been measured potentiometrically. For instance, the stability constant of copper(II) complexation were determine and the model system generated an excellent fit. Stability constants with several metals have been determined and will be reported.

Black and green pigments based on chromium-cobalt spinels

Energy Technology Data Exchange (ETDEWEB)

Eliziario, Sayonara A., E-mail: sayonaraea@iq.unesp.br [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Andrade, Jeferson M. de [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Lima, Severino J.G. [Departamento de Engenharia Mecanica, CT, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Paskocimas, Carlos A. [Universidade Federal do Rio Grande do Norte, CT, Natal, RN (Brazil); Soledade, Luiz E.B. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Hammer, P.; Longo, E. [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Souza, Antonio G.; Santos, Ieda M.G. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil)

2011-09-15

Highlights: {yields} Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were prepared by the polymeric precursor method. {yields} Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4} displayed a dark color and CoCr{sub 2}O{sub 4} was green. {yields} The colors were related to the different oxidation states of Cr and Co. {yields} Cobalt enrichment result in an increasing presence of Co(III) and a decrease amount of Cr(VI). - Abstract: Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 deg. C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV-vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4}, displayed a dark color, without the Co{sup 3+} reduction observed in Co{sub 3}O{sub 4} between 900 and 950 deg. C. The spinel with higher chromium amount, CoCr{sub 2}O{sub 4}, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV-vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment.

Tris(2,2′-bipyridine-κ2 N,N′)cobalt(III) bis­[bis­(pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)cobaltate(III)] perchlorate dimethyl­formamide hemisolvate 1.3-hydrate

Science.gov (United States)

Golenya, Irina A.; Boyko, Alexander N.; Kotova, Natalia V.; Haukka, Matti; Iskenderov, Turganbay S.

2012-01-01

In the title compound, [Co(C10H8N2)3][Co(C7H3NO4)2]2(ClO4)·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudoocta­hedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxyl­ate O atoms of two doubly deprotonated pyridine-2,6-dicarboxyl­ate ligands in a distorted octa­hedral geometry. One dimethyl­formamide solvent mol­ecule and two water mol­ecules are half-occupied and one water mol­ecule is 0.3-occupied. O—H⋯O hydrogen bonds link the water mol­ecules, the perchlorate anions and the complex anions. π–π inter­actions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3) Å]. PMID:23125573

Cobalt Cardiomyopathy Secondary to Hip Arthroplasty: An Increasingly Prevalent Problem

Directory of Open Access Journals (Sweden)

Russel Tilney

2017-01-01

Full Text Available A forty-year-old man experienced worsening heart failure four years following bilateral complicated total hip replacement. His condition was extensively worked up but no underlying pathology was immediately evident. Given the cobalt-chromium alloy component present in the hip arthroplasties, the raised cobalt blood levels, and a fitting clinical picture coupled with radiological findings, the patient underwent right hip revision. Evidence of biotribocorrosion was present on direct visualisation intraoperatively. The patient subsequently experienced symptomatic improvement (NYHA class III to class I and echocardiography showed recovery of ejection fraction. Cobalt exists as a bivalent and trivalent molecule in circulation and produces a cytotoxicity profile similar to nanoparticles, causing neurological, thyroid, and cardiological pathology. Blood levels are not entirely useful as there is no identifiable conversion factor for levels in whole blood, serum, and erythrocytes which seem to act independently of each other. Interestingly cobalt cardiomyopathy is frequently compounded by other possible causes of cardiomyopathy such as alcohol and a link has been postulated. Definitive treatment is revision of the arthroplasty as other treatments are unproven.

Cryosurvival of goat spermatozoa in tris-egg yolk extender ...

African Journals Online (AJOL)

The effect of vitamin E supplementation in tris-egg yolk extender on sperm parameters of West African Dwarf (WAD) goat bucks was determined. Tris-egg yolk extenders supplemented with different levels of ... of WAD goat bucks during cryopreservation. Keywords: Antioxidants, bucks, freezing, oxidative stress, sperm ...

Synthesis, structure, properties and immobilization on a gold surface of the monoribbed-functionalized tris-dioximate cobalt(II) clathrochelates and an electrocatalytic hydrogen production from H+ ions.

Science.gov (United States)

Voloshin, Y Z; Belov, A S; Vologzhanina, A V; Aleksandrov, G G; Dolganov, A V; Novikov, V V; Varzatskii, O A; Bubnov, Y N

2012-05-28

The cycloaddition of the mono- and dichloroglyoximes to the cobalt(II) bis-α-benzyldioximate afforded the cobalt(II) mono- and dichloroclathrochelates in moderate yields (40-60%). These complexes undergo nucleophilic substitution of their reactive chlorine atoms with aliphatic amines, alcohols and thiolate anions. In the case of ethylenediamine and 1,2-ethanedithiol, only the macrobicyclic products with α,α'-N(2)- and α,α'-S(2)-alicyclic six-numbered ribbed fragments were obtained. The cobalt(II) cage complexes with terminal mercapto groups were synthesized using aliphatic dithiols. The crystal and molecular structures of the six cobalt(II) clathrochelates were obtained by X-ray diffraction. Their CoN(6)-coordination polyhedra possess a geometry intermediate between a trigonal prism and a trigonal antiprism, and the encapsulated cobalt(II) ions are shifted from their centres due to the structural Jahn-Teller effect with the Co-N distances varying significantly (by 0.10-0.26 Å). The electrochemistry of the complexes obtained was studied by cyclic voltammetry (CV). The anodic waves correspond to the quasi-reversible Co(2+/3+) oxidations, whereas the cathodic ranges contain the quasi-reversibile waves assigned to the Co(2+/+) reductions; all the cobalt(i)-containing clathrochelate anions formed are stable in the CV time scale. The electrocatalytic properties of the cobalt complexes obtained were studied in the production of hydrogen from H(+) ions: the addition of HClO(4) resulted in the formation of the same catalytic cathodic reduction Co(2+/+) waves. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H(2) in high Faraday yields. The efficiency of this electrocatalytic process was enhanced by an immobilization of the complexes with terminal mercapto groups on a surface of the working gold electrode.

Piezoelectric properties and thermal stabilities of cobalt-modified potassium bismuth titanate

International Nuclear Information System (INIS)

Guo, Zhen-Lei; Wang, Chun-Ming; Zhao, Tian-Long; Yu, Si-Long; Cao, Zhao-Peng

2013-01-01

The cobalt-modified potassium bismuth titanate (K 0.5 Bi 4.5 Ti 4 O 15 , KBT) piezoelectric ceramics have been prepared using conventional solid–state reaction. X-ray diffraction analysis revealed that the cobalt-modified KBT ceramics have a pure four-layer (m = 4) Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of cobalt-modified KBT ceramics were investigated in detail. The piezoelectric activities of KBT ceramics were significantly improved by the cobalt modification. The reasons for piezoelectric activities enhancement with cobalt modification were given. The piezoelectric coefficient d 33 and Curie temperature T c for the 5 mol% cobalt-modified KBT ceramics (KBT-Co5) were found to be 28 pC/N and 575 °C, respectively. The DC resistivity, frequency constants (N p and N t ), and electromechanical properties at elevated temperature were investigated, indicating the cobalt-modified KBT piezoelectric ceramics possess stable piezoelectric properties up to 500 °C. The results show the cobalt-modified KBT ceramics are potential materials for high temperature piezoelectric applications. - Highlights: • We examine the piezoelectric properties of the cobalt-modified K 0.5 Bi 4.5 Ti 4 O 15 . • A high level of piezoelectric activities (d 33 = 28 pC/N) are obtained. • High Curie temperature (T c = 575 °C) is acquired for the optimal composition. • The Co-modified K 0.5 Bi 4.5 Ti 4 O 15 is promising as high temperature materials

In situ fabrication and characterization of cobalt ferrite nanorods/graphene composites

International Nuclear Information System (INIS)

Fu, Min; Jiao, Qingze; Zhao, Yun

2013-01-01

Cobalt ferrite nanorods/graphene composites were prepared by a one-step hydrothermal process using NaHSO 3 as the reducing agent and 1-propyl-3-hexadecylimidazolium bromide as the structure growth-directing template. The reduction of graphene oxide and the in situ formation of cobalt ferrite nanorods were accomplished in a one-step reaction. The structure and morphology of as-obtained composites were characterized by field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, atomic force microscope, X-ray diffractometer, Fourier transform infrared spectra, X-ray photoelectron spectroscopy and Raman spectroscopy. Uniform rod-like cobalt ferrites with diameters of about 100 nm and length of about 800 nm were homogeneously distributed on the graphene sheets. The hybrid materials showed a saturation magnetization of 42.5 emu/g and coercivity of 495.1 Oe at room temperature. The electromagnetic parameters were measured using a vector network analyzer. A minimum reflection loss (RL) of − 25.8 dB was observed at 16.1 GHz for the cobalt ferrite nanorods/graphene composites with a thickness of 2 mm, and the effective absorption frequency (RL < − 10 dB) ranged from 13.5 to 18.0 GHz. The composites exhibited better absorbing properties than the cobalt ferrite nanorods and the mixture of cobalt ferrite nanorods and graphene. - Highlights: • Reduction of GO and formation of ferrites were accomplished in a one-step reaction. • Ionic liquid was used to control 1D growth of ferrite nanorods for the first time. • Cobalt ferrite nanorods/graphene composites showed dielectric and magnetic loss. • Cobalt ferrite nanorods/graphene composites exhibited better absorbing properties

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds.

Science.gov (United States)

Pindwal, Aradhana; Yan, KaKing; Patnaik, Smita; Schmidt, Bradley M; Ellern, Arkady; Slowing, Igor I; Bae, Cheolbeom; Sadow, Aaron D

2017-11-22

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe 2 ) 3 } 3 (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI 3 THF n and 3 equiv of KC(SiHMe 2 ) 3 . X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C 3 -symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe 2 ) 3 } 3 and DFT calculations. The Ln↼HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in 1a (ΔH ⧧ = 8.2(4) kcal·mol -1 ; ΔS ⧧ = -1(2) cal·mol -1 K -1 ) and 1a-d 9 (ΔH ⧧ = 7.7(3) kcal·mol -1 ; ΔS ⧧ = -4(2) cal·mol -1 K -1 ). Comparisons of lineshapes, rate constants (k H /k D ), and slopes of ln(k/T) vs 1/T plots for 1a and 1a-d 9 reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five β-Si-H⇀Ln and one γ-C-H⇀Ln. The calculations also suggest the pathway for Ln↼HSi/SiH exchange involves rotation of a single C(SiHMe 2 ) 3 ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 °C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe 2 ) 3 } 3 and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox Me2 ) 2 ) give {MeC(Ox Me2 ) 2 }Ln{C(SiHMe 2 ) 3 } 2 , and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).

Gamma dosimetry using lyoluminescence of Tris (hydroxymethyl) aminomethane

International Nuclear Information System (INIS)

Mehta, S.K.; Oommen, I.K.; Sengupta, S.; Soman, S.D.

1983-01-01

Lyoluminescence (LL) of Tris (hydroxymethyl) aminomethane has been studied and compared with the LL of glucose, mannose, valine and glutamine. Among these materials, Tris (hydroxymethyl) aminomethane on dissolution in luminol shows the highest LL sensitivity and stability. The linear dosimetric range of this system is 0.1-2x10 2 Gy which makes it useful in the fields of radiotherapy and radiation processing of food. (orig.)

Few studies of the effect of diluents on extraction of cobalt with D2EHPA. D2EHPA ni yoru Co no chushutsu ni ataeru kishakuzai no eikyo ni kansuru jakkan no kento

Energy Technology Data Exchange (ETDEWEB)

Aranae, M.; Nakataka, Y.; Wakamatsu, T. (Kyoto Univ., Kyoto (Japan). Faculty of Engineering); Saito, I.; Sakamoto, H. (Environment Research Inst. Resources Technical Tsukuba (Japan))

1991-12-27

Study was made on extraction of cobalt from weak acid solution with di-(2-ethylhexyl) phosphoric acid (D2EHPA) using various polar diluents such as benzene, toluene, o-xylene, m-xylene, n-heptane, cyclohexane and n-hepatne-benzene mixtures. Extraction efficiency of cobalt has decreased in the order, n-heptane > cyclohexane > m-xylene > o-xylene > toluene > benzene and this order has been in good agreement with the decreasing order of solubility parameters of diluents,and has shown the possibility of application of regular solution theory. When n-heptane and cyclohexane as diluents, in low loading ratio(L),were used Co-D2EHPA polymer were formed compared to other diluents. On the other hand when mixture of n-heptane/benzene was used as diluent, the efficiency of extraction, salting-out effect and formation of Co-D2EHPA polymer has changed with the texture of mixture.This change may be due to the effect of L and it has been thought for the necessity of investigation of extraction of cobalt in low polar diluents. 13 refs., 5 figs., 2 tabs.

New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries

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Shintaro Iwamoto

2015-07-01

Full Text Available Derivatives of tris-fused TTF extended with two ethanediylidenes (5, tris- and pentakis-fused TTFs extended with two thiophene-2,5-diylidenes (6–9 were successfully synthesized. Cyclic voltammograms of the tetrakis(n-hexylthio derivative of 5 and 7 (5d, 7d consisted of two pairs of two-electron redox waves and two pairs of one-electron redox waves. On the other hand, four pairs of two-electron redox waves and two pairs of one-electron redox waves were observed for the tetrakis(n-hexylthio derivative of 9 (9d. Coin-type cells using the bis(ethylenedithio derivatives of 5 (5b, 6 (6b and the tetrakis(methylthio derivatives of 5 (5c and 8 (8c as positive electrode materials showed initial discharge capacities of 157–190 mAh g−1 and initial energy densities of 535–680 mAh g−1. The discharge capacities after 40 cycles were 64–86% of the initial discharge capacities.

Cobalt(II Complexes with N,N,N-Scorpionates and Bidentate Ligands: Comparison of Hydrotris(3,5-dimethylpyrazol-1-ylborate Tp* vs. Phenyltris(4,4-dimethyloxazolin-2-ylborate ToM to Control the Structural Properties and Reactivities of Cobalt Centers

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Toshiki Nishiura

2018-06-01

Full Text Available Scorpionate ligands Tp* (hydrotris(3,5-dimethylpyrazol-1-ylborate and ToM (tris(4,4-dimethyloxazolin-2-ylphenylborate complexes of cobalt(II with bidentate ligands were synthesized. Both Tp* and ToM coordinate to cobalt(II in a tridentate fashion when the bidentate ligand is the less hindered acetylacetonate. In crystal structures, the geometry of cobalt(II supported by the N3O2 donor set in the Tp* complex is a square-pyramid, whereas that in the ToM complex is close to a trigonal-bipyramid. Both Tp*- and ToM-acac complexes exhibit solvatochromic behavior, although the changing structural equilibria of these complexes in MeCN are quite different. In the bis(1-methylimidazol-2-ylmethylphenylborate (LPh complexes, Tp* retains the tridentate (к3 mode, whereas ToM functions as the bidentate (к2 ligand, giving the tetrahedral cobalt(II complex. The bowl-shaped cavity derived from the six methyl groups on ToM lead to susceptibility to the bulkiness of the opposite bidentate ligand. The entitled scorpionate compounds mediate hydrocarbon oxidation with organic peroxides. Allylic oxidation of cyclohexene occurs mainly on the reaction with tert-butyl hydroperoxide (TBHP, although the catalytic efficiency of the scorpionate ligand complexes is lower than that of Co(OAc2 and Co(acac2. On cyclohexane oxidation with meta-chloroperbenzoic acid (mCPBA, both ToM and Tp* complexes function as catalysts for hydroxylation. The higher electron-donating ToM complexes show faster initial reaction rates compared to the corresponding Tp* complexes.

Theoretical analysis of the influence of chelate-ring size and vicinal effects on electronic circular dichroism spectra of cobalt(III) EDDA-type complexes.

Science.gov (United States)

Wang, Ai; Wang, Yuekui; Jia, Jie; Feng, Lixia; Zhang, Chunxia; Liu, Linlin

2013-06-20

To assess the contributions of configurational and vicinal effects as well as chelate-ring size to rotational strengths, the geometries of a series of cobalt(III) complexes [Co(EDDA-type)(L)](±) with the tetradentate EDDA-type ligands, EDDA (ethylenediamine-N,N'-diacetate), DMEDDA (N,N'-dimethylethylenediamine-N,N'-diacetate), DEEDDA (N,N'-diethylethylenediamine-N,N'-diacetate), and a bidentate ancillary ligand L (L = ethylenediamine, oxalate, carbonate, (S)-alanine, and malonate) in aqueous solution have been optimized at the DFT/B3LYP/6-311++G(2d,p) level of theory. Based on the optimized geometries, the excitation energies and oscillator and rotational strengths have been calculated using the time-dependent density functional theory (TDDFT) method with the same functional and basis set. The calculated circular dichroism (CD) curves are in excellent agreement with the observed ones except for some small red or blue shifts in peak wavelengths. For the influence of chelate-ring size of the bidentate ligands on the CD intensities, a qualitative analysis together with the quantitative TDDFT calculation reveal that it depends on the symmetry of the cobalt-EDDA backbone. For the s-cis-isomers, the influence is negligible due to the perturbation is symmetric. For the uns-cis-isomers, the perturbation is unsymmetric. Since a small ring size means a large perturbation, this leads to the integral CD intensities decreasing with increasing the chelate ring size. The vicinal effects of asymmetric nitrogens incorporate both the substitutent effects and conformational relaxation effects, with the former being dominant. By analyzing the contributions of chiral arrays to rotational strengths, we found that the part of contributions dominated by the S-type chiral nitrogens could be considered as a good measure for the vicinal effects of chiral nitrogens. In addition, we found that the twist form (δ/λ) of the backbone ethylenediamine ring (E-ring) of the coordinated EDDA

Complexation of f elements by tripodal ligands containing aromatic nitrogens. Application to the selective extraction of actinides(III)

International Nuclear Information System (INIS)

Wietzke, Raphael

1999-01-01

This work initiates a research project, whose aim is the actinides(lll)/lanthanides(III) separation by liquid-liquid extraction. We were interested in the study of the coordination chemistry of lanthanides(III) and uranium(III) (uranium(III) as model for the actinides(III)), with the aim to show differences between the two families and to better understand the coordination properties involved in the extraction process. We studied the lanthanide(III) and uranium(III) complexation with tripodal ligands containing aromatic nitrogens. Several tripodal ligands were synthesized varying the type and the number of the donor atoms. The lanthanide(III) complexes have been characterized in the solid state and in solution (by several techniques: "1H NMR, ESMS, luminescence, UV spectrophotometry, conductometry). Differences in the coordination were found depending on the nature of the donor atoms. The new ligands, tris(2-pyrazinylmethyl)amine (tpza) et tris(N,N-diethyl-2-carbamoyl-6- pyridylmethyl)amine (tpaa), have shown a selectivity for the actinides(III) with promising results in liquid-liquid extraction. The comparison between the lanthanum(III) and uranium(III) complexes with the ligand tpza showed differences in the bonding nature, which could be attributed to a covalent contribution to the metal-ligand bond. (author) [fr

2-Vinylpyridine–tris(pentafluorophenylborane hexane monosolvate

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Marcus Klahn

2012-04-01

Full Text Available The title compound, C7H7N·B(C6F53·C6H14, was obtained by the stoichiometric reaction of 2-vinylpyridine and tris(pentafluorophenylborane in toluene. The formed adduct exhibits a restricted rotation along the B—N bond resulting in an asymmetry, which can be also observed in the 19F NMR spectra. The B—N distance is equivalent to the distances found for 2-methylpyridine and 2-ethylpyridine B(C6F53 adducts. For the final refinement, the contributions of disordered solvent molecules were removed from the diffraction data with SQUEEZE in PLATON [van der Sluis & Spek (1990. Acta Cryst. A46, 194–201; Spek (2009. Acta Cryst. D65, 148–155].

Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

International Nuclear Information System (INIS)

Ramesh, Thimmasandra Narayan

2010-01-01

The isothermal decomposition of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature leads to the formation of Co 3 O 4 . The phase evolution during the decomposition process was monitored using powder X-ray diffraction. The transformation of cobalt hydroxide to cobalt oxide occurs via three phase mixture while cobalt hydroxynitrate to cobalt oxide occurs through a two phase mixture. The nature of the sample and its preparation method controls the decomposition mechanism. The comparison of topotactical relationship between the precursors to the decomposed product has been reported in relation to polytypism. - Graphical abstract: Isothermal thermal decomposition studies of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature show the metastable phase formed prior to Co 3 O 4 phase.

Redetermination of dicerium(III) tris-(sulfate) tetra-hydrate.

Science.gov (United States)

Xu, Xin

2007-12-06

Ce(2)(SO(4))(3)(H(2)O)(4) was obtained hydro-thermally from an aqueous solution of cerium(III) oxide, trimethyl-amine and sulfuric acid. The precision of the structure determination has been significantly improved compared with the previous result [Dereigne (1972 ▶). Bull. Soc. Fr. Mineral. Cristallogr.95, 269-280]. The coordination about the two Ce atoms is achieved by seven and six bridging O atoms from sulfate anions. Each S atom makes four S-O-Ce linkages through bridging O atoms. The coordination sphere of each Ce is completed by two water molecules, which act as terminal ligands.

Trigonal Prismatic Tris-pyridineoximate Transition Metal Complexes: A Cobalt(II) Compound with High Magnetic Anisotropy.

Science.gov (United States)

Pavlov, Alexander A; Savkina, Svetlana A; Belov, Alexander S; Nelyubina, Yulia V; Efimov, Nikolay N; Voloshin, Yan Z; Novikov, Valentin V

2017-06-19

High magnetic anisotropy is a key property of paramagnetic shift tags, which are mostly studied by NMR spectroscopy, and of single molecule magnets, for which magnetometry is usually used. We successfully employed both these methods in analyzing magnetic properties of a series of transition metal complexes, the so-called clathrochelates. A cobalt complex was found to be both a promising paramagnetic shift tag and a single molecule magnet because of it having large axial magnetic susceptibility tensor anisotropy at room temperature (22.5 × 10 -32 m 3 mol -1 ) and a high effective barrier to magnetization reversal (up to 70.5 cm -1 ). The origin of this large magnetic anisotropy is a negative value of zero-field splitting energy that reaches -86 cm -1 according to magnetometry and NMR measurements.

Highly dispersive ion exchangers in the analytical chemistry of uranium, particularly regarding separation methods

International Nuclear Information System (INIS)

Schoening, R.

1975-01-01

The reaction of water-insoluble polyvinyl pyrrolidon with uranium VI was investigated and a determination method for uranium was worked out in which the polyvinyl pyrrolidon was used as specific exchanger. Good separations of uranium from numerous transition metal ions were achieved here. The application of this exchanger for a fast and simple elution and determination method was of particular importance. A possible sorption mechanism was suggested based on the capacity curve of uranium with polyvinyl pyrrolidon and nitrogen and chloride content at maximum load. The sorption occurs by coordination of the carbonyl oxygen of single pyrrolidon rings with the protons of the complex acides and uranium. This assumption is supported by IR investigations. The sorbability of other inorganic acids was also investigated and possible structures were formulated for the sorption mechanism. In addition to this, ion exchangers were prepared based on cellulose by converting cellulose powder with aziridine and tris-1-aziridinyl-phosphine oxide. A polyethylene imine cellulose of high capacity was obtained in the conversion of cellulose powder with aziridine. This exchanger absorbs cobalt III very strongly. The exchanger loaded with cobalt III was used to separate the uranium as cyanato complex. The exchanger obtained in converting chlorated cellulose with tris-1-aziridinyl phosphine oxide also absorbs uranium VI very strongly. Thus a separation method of high specifity and selectivity was developed. (orig.) [de

Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

Indian Academy of Sciences (India)

of 60 mV were observed at. 100 mV s. −1 for CoOx−MWNT/GCE. An anodic peak at. 100 mV attributed to Co(II)/Co(III) redox transition associated with the electrode surface. The cathodic peak at 20 mV corre- spond to the reduction of various cobalt oxide species formed during the anodic sweep. The stability of the modified ...

Blood doping by cobalt. Should we measure cobalt in athletes?

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Guidi Gian

2006-07-01

Full Text Available Abstract Background Blood doping is commonplace in competitive athletes who seek to enhance their aerobic performances through illicit techniques. Presentation of the hypothesis Cobalt, a naturally-occurring element with properties similar to those of iron and nickel, induces a marked and stable polycythemic response through a more efficient transcription of the erythropoietin gene. Testing the hypothesis Although little information is available so far on cobalt metabolism, reference value ranges or supplementation in athletes, there is emerging evidence that cobalt is used as a supplement and increased serum concentrations are occasionally observed in athletes. Therefore, given the athlete's connatural inclination to experiment with innovative, unfair and potentially unhealthy doping techniques, cobalt administration might soon become the most suited complement or surrogate for erythropoiesis-stimulating substances. Nevertheless, cobalt administration is not free from unsafe consequences, which involve toxic effects on heart, liver, kidney, thyroid and cancer promotion. Implications of the hypothesis Cobalt is easily purchasable, inexpensive and not currently comprehended within the World Anti-Doping Agency prohibited list. Moreover, available techniques for measuring whole blood, serum, plasma or urinary cobalt involve analytic approaches which are currently not practical for antidoping laboratories. Thus more research on cobalt metabolism in athletes is compelling, along with implementation of effective strategies to unmask this potentially deleterious doping practice

Uranyl(VI) and lanthanum(III) complexes with functionalized macrocyclic and macroacyclic Schiff bases

International Nuclear Information System (INIS)

Aguiari, A.; Brianese, N.; Tamburini, S.; Vigato, P.A.

1995-01-01

Acyclic Schiff bases have been prepared by [2 + 1] condensation of 2,6-diformyl-4-chlorophenol and H 2 NCH 2 [CH 2 XCH 2 ] n CH 2 NH 2 (n =3D 0 H 2 -I; X =3D NH, S, O n =3D 1 H 2 -II...H 2 -IV; X =3D 0 n =3D 2 H 2 -V; X =3D 0 n =3D 3 H 2 -VI). The related uranlyl(VI) and lanthanum (III) complexes have bee synthesized by reaction by reaction of the preformed ligands with the appropriate salt or by the template procedure, in the presence of base. No base was employed in the preparation of lanthanum (III) complexes, La(H 2 -II)(NO 3 ) 3 , La(H 2 -IV)(NO 3 ) 3 where the Schiff bases coordinate as neutral chelate ligands. These acyclic complexes have been used for further condensation, and symmetric and asymmetric cyclic complexes have been obtained by their reaction with the polyamines H 2 NCH 2 [CH 2 XCH 2 ]nCH 2 NH 2 or with 4,4'-diaminodibenzo -18-crown-6. By reaction with 4-aminobenzo-15-crown-5 or 2-amino-methyl-15-crown-5, the same acyclic complexes give rise to functionalized complexes bearing crown-ether moieties. Analogously, the acyclic ligand H 3 -IXX, prepared by condensation of 2,6 diformyl-4-chlorophenol and tris(aminoethyl)amine, forms mono and homodinuclear lanthanum (III) complexes, which may undergo further condensation when reacted with primary functionalized amines. (authors). 42 refs., 2 figs., 2 schemes, 1 tab

Lump Kinetic Analysis of Syngas Composition Effect on Fischer-Tropsch Synthesis over Cobalt and Cobalt-Rhenium Alumina Supported Catalyst

Directory of Open Access Journals (Sweden)

Dewi Tristantini

2016-03-01

Received: 10th November 2015; Revised: 10th February 2016; Accepted: 16th February 2016 How to Cite: Tristantini, D., Suwignjo, R.K. (2016. Lump Kinetic Analysis of Syngas Composition Effect on Fischer-Tropsch Synthesis over Cobalt and Cobalt-Rhenium Alumina Supported Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 84-92. (doi:10.9767/bcrec.11.1.424.84-92 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.424.84-92

Energetic co-ordination compounds: synthesis, characterization and thermolysis studies on bis-(5-nitro-2H-tetrazolato-N2)tetraammine cobalt(III) perchlorate (BNCP) and its new transition metal (Ni/Cu/Zn) perchlorate analogues

International Nuclear Information System (INIS)

Talawar, M.B.; Agrawal, A.P.; Asthana, S.N.

2005-01-01

Bis-(5-nitro-2H-tetrazolato-N 2 )tetraammine[cobalt(III)/nickel(III)] perchlorates (BNCP/BNNP) and mono-(5-nitro-H-tetrazolato-N)triammine [copper(II)/zinc(II)] perchlorates (MNCuP/MNZnP) have been synthesized during this work. The synthesis was carried out by addition of carbonato tetraammine metal [Co/Ni/Cu/Zn] nitrate [CTCN/CTNN/CTCuN/CTZnN] to the aqueous solution of sodium salt of 5-nitrotetrazole followed by reaction with perchloric acid. The precursors were synthesized by the reaction of aqueous solution of their respective nitrates with ammonium carbonate at 70 deg. C. The complexes and their precursors were characterized by determining metal and perchlorate content as well as infrared (IR), electron spectra for chemical analysis (ESCA) and X-ray diffraction (XRD) techniques. The TG profiles indicated that BNCP, BNNP and MNCuP are thermally stable up to the temperature of 260-278 deg. C unlike MNZnP (150 deg. C). Sudden exothermic decomposition was observed in case of bis-(5-nitro-2H-tetrazolato-N 2 )tetraammine cobalt(III) perchlorate, bis-(5-nitro-2H-tetrazolato-N 2 )tetraammine nickel(III) perchlorate and mono-(5-nitro-H-tetrazolato-N)triammine zinc(II) perchlorate resulting in the severe damage of the sample cup. Sensitivity data indicated that the Co/Ni/Cu complexes are more friction sensitive (3-4.8 kg) than mono-(5-nitro-H-tetrazolato-N)triammine zinc(II) perchlorate (14 kg). The impact sensitivity results of the complexes corresponded to h 50% of 30-36 cm

Spectroscopic studies of an europium(III) tris-β-diketonate complex bearing a pyrazolylpyridine ligand

International Nuclear Information System (INIS)

Moreira dos Santos, Antonio; Coelho, Ana C.; Almeida Paz, Filipe A.; Rocha, Joao; Goncalves, Isabel S.; Carlos, Luis D.

2008-01-01

A new europium(III) complex, Eu(BTA) 3 (ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate) (where BTA: 1-benzoyl-3,3,3-trifluoroacetonate), was synthesised by simple ligand exchange with the solvent adduct Eu(BTA) 3 (H 2 O) 2 . The compound was characterised by elemental analysis, thermogravimetry, FTIR, FT Raman and photoluminescence spectroscopies. A significant increase of the 5 D 0 lifetime of the complex, relative to the value found for the water-coordinated adduct (from 0.657 ± 0.001 to 0.835 ± 0.002 ms), and a larger contribution of the ligand levels to the excitation spectrum indicate a better photoluminescence performance for the former complex

ssDNA degradation along capillary electrophoresis process using a Tris buffer.

Science.gov (United States)

Ric, Audrey; Ong-Meang, Varravaddheay; Poinsot, Verena; Martins-Froment, Nathalie; Chauvet, Fabien; Boutonnet, Audrey; Ginot, Frédéric; Ecochard, Vincent; Paquereau, Laurent; Couderc, François

2017-06-01

Tris-Acetate buffer is currently used in the selection and the characterization of ssDNA by capillary electrophoresis (CE). By applying high voltage, the migration of ionic species into the capillary generates a current that induces water electrolysis. This phenomenon is followed by the modification of the pH and the production of Tris derivatives. By injecting ten times by capillary electrophoresis ssDNA (50 nM), the whole oligonucleotide was degraded. In this paper, we will show that the Tris buffer in the running vials is modified along the electrophoretic process by electrochemical reactions. We also observed that the composition of the metal ions changes in the running buffer vials. This phenomenon, never described in CE, is important for fluorescent ssDNA analysis using Tris buffer. The oligonucleotides are degraded by electrochemically synthesized species (present in the running Tris vials) until it disappears, even if the separation buffer in the capillary is clean. To address these issues, we propose to use a sodium phosphate buffer that we demonstrate to be electrochemically inactive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploration of spectroscopic properties of solvated tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III)red hybrid organic complex for solution processed OLEDs and displays

International Nuclear Information System (INIS)

Chitnis, Dipti; Thejokalyani, N.; Dhoble, S.J.

2017-01-01

In order to explore the spectroscopic properties of a novel europium activated hybrid organic tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III), Eu(TTA) 3 bipy phosphor in various solvents at different pH and molar concentrations, UV–vis optical absorption and photoluminescence spectra were carried out. With a variation in the solvent from basic (chloroform, toluene, tetrahydrofuran) to acidic (acetic acid, formic acid) media, staggering differences in optical absorptions and optical densities were noticed with hypsochromic shift in the absorption peaks. The optical density was found to be maximum for the complex with pH= 7.0 and the intensity as well as optical density gradually decreased when pH is lowered to 6.0 or raised to 8.0 (at an interval of 0.5), proving that the complex is pH sensitive. It's optical energy gap and stokes shift values in various organic solvents were also calculated on the basis of Lippert-Mataga plot. The exploration of spectroscopic properties of solvated Eu(TTA) 3 bipy complex demonstrates its prospective for solution processed OLEDs and display devices. - Graphical abstract: Pictorial depiction of photoluminescence in solvated Eu(TTA) 3 bipy complex under UV light.

Cobalt products from real waste fractions of end of life lithium ion batteries.

Science.gov (United States)

Pagnanelli, Francesca; Moscardini, Emanuela; Altimari, Pietro; Abo Atia, Thomas; Toro, Luigi

2016-05-01

An innovative process was optimized to recover Co from portable Lithium Ion Batteries (LIB). Pilot scale physical pretreatment was performed to recover electrodic powder from LIB. Co was extracted from electrodic powder by a hydrometallurgical process including the following main stages: leaching (by acid reducing conditions), primary purification (by precipitation of metal impurities), solvent extraction with D2EPHA (for removal of metal impurities), solvent extraction with Cyanex 272 (for separation of cobalt from nickel), cobalt recovery (by precipitation of cobalt carbonate). Tests were separately performed to identify the optimal operating conditions for precipitation (pH 3.8 or 4.8), solvent extraction with D2EHPA (pH 3.8; Mn/D2EHPA=4; 10% TBP; two sequential extractive steps) and solvent extraction with Cyanex 272 (pH 3.8; Cyanex/Cobalt=4, 10% TBP, one extractive step). The sequence of optimized process stages was finally performed to obtain cobalt carbonate. Products with different degree of purity were obtained depending on the performed purification steps (precipitation with or without solvent extraction). 95% purity was achieved by implementation of the process including the solvent extraction stages with D2EHPA and Cyanex 272 and final washing for sodium removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interfacial exciplex electroluminescence between diamine derivatives with starburst molecular structure and tris(acetylacetonato)-(mono-phenothroline) thulium

International Nuclear Information System (INIS)

He Hong; Li Wenlian; Su Zisheng; Chu Bei; Bi Defeng; Chen Yiren; Wang Dan; Su Wenming; Li Bin

2009-01-01

The authors demonstrate the interfacial exciplex electroluminescence (EL) between tris(acetylacetonato)-(mono-phenothroline) thulium [Tm(AcA) 3 phen] and two diamine derivatives with starburst molecular structure- 4,4',4''-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA) and 4,4',4''-tris[3-methyl-pheny(phenyl)-amino]triphenyl-amine (m-MTDATA), both of which have the same ionization potential (IP) (approximately 5.1 eV). When the Tm-complex and the two diamine derivatives are respectively used as the electron accepter and donors, the two EL devices exhibit different exciplex emissions, which verifies our previously reported opinion regarding the effect of the different substitutes on exciplex emission [W.M. Su, W.L. Li, Q. Xin, Z.S. Su, B. Chu, D.F. Bi, H. He, J.H. Niu, Appl. Phys. Lett. 91 (2007) 043508]. When the mixture of the two diamine derivatives is used as a donor, a white EL device with the Commission International de l'Eclairage (CIE) coordinates of (0.277, 0.323) is achieved. The exciplex formation mechanisms of the devices with the two different donors are discussed

Cobalt release from inexpensive jewellery

DEFF Research Database (Denmark)

Thyssen, Jacob Pontoppidan; Jellesen, Morten Stendahl; Menné, Torkil

2010-01-01

. Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future......Objectives: The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. Methods: The cobalt spot test was used to assess cobalt release from all items...

THE COORDINATION COMPOUNDS OF COBALT (II, III) WITH DITHIOCARBAMIC ACID DERIVATIVES — MODIFICATORS OF HYDROLYTIC ENZYMES ACTIVITY

OpenAIRE

L. D. Varbanets; О. V. Matselyukh; N. А. Nidyalkova; Е. V. Аvdiyuk; А. V. Gudzenko; I. I. Seifullina; G. N. Маsаnоvets; N. V. Khitrich

2013-01-01

Chloride, bromide and isothiocyanate complexes of cobalt(II) with N-substituted thiocarbamoyl-N?-pentamethylenesulfenamides (1)–(12), and also complexes of cobalt(II, Ш) with derivatives of morpholine-4-carbodithioic acid (13)–(18) have been used as modificators of enzymes of hydrolytic action — Bacillus thurin-giensis ІМВ В-7324 peptidases, Bacillus subtilis 147 and Aspergillus flavus var. oryzae 80428 amylases, Eupenicillium erubescens 248 and Cryptococcus albidus 1001 rhamnosidases. It was...

Silver Nanoparticle-Enhanced Resonance Raman Sensor of Chromium(III) in Seawater Samples.

Science.gov (United States)

Ly, Nguyễn Hoàng; Joo, Sang-Woo

2015-04-29

Tris(hydroxymethyl)aminomethane ethylenediaminetetraacetic acid (Tris-EDTA), upon binding Cr(III) in aqueous solutions at pH 8.0 on silver nanoparticles (AgNPs), was found to provide a sensitive and selective Raman marker band at ~563 cm-1, which can be ascribed to the metal-N band. UV-Vis absorption spectra also supported the aggregation and structural change of EDTA upon binding Cr(III). Only for Cr(III) concentrations above 500 nM, the band at ~563 cm-1 become strongly intensified in the surface-enhanced Raman scattering spectra. This band, due to the metal-EDTA complex, was not observed in the case of 50 mM of K+, Cd2+, Mg2+, Ca2+, Mn2+, Co2+, Na+, Cu2+, NH4+, Hg2+, Ni2+, Fe3+, Pb2+, Fe2+, and Zn2+ ions. Seawater samples containing K, Mg, Ca, and Na ion concentrations higher than 8 mM also showed the characteristic Raman band at ~563 cm-1 above 500 nM, validating our method. Our approach may be useful in detecting real water samples by means of AgNPs and Raman spectroscopy.

Axial Ligation and Redox Changes at the Cobalt Ion in Cobalamin Bound to Corrinoid Iron-Sulfur Protein (CoFeSP or in Solution Characterized by XAS and DFT.

Directory of Open Access Journals (Sweden)

Peer Schrapers

Full Text Available A cobalamin (Cbl cofactor in corrinoid iron-sulfur protein (CoFeSP is the primary methyl group donor and acceptor in biological carbon oxide conversion along the reductive acetyl-CoA pathway. Changes of the axial coordination of the cobalt ion within the corrin macrocycle upon redox transitions in aqua-, methyl-, and cyano-Cbl bound to CoFeSP or in solution were studied using X-ray absorption spectroscopy (XAS at the Co K-edge in combination with density functional theory (DFT calculations, supported by metal content and cobalt redox level quantification with further spectroscopic methods. Calculation of the highly variable pre-edge X-ray absorption features due to core-to-valence (ctv electronic transitions, XANES shape analysis, and cobalt-ligand bond lengths determination from EXAFS has yielded models for the molecular and electronic structures of the cobalt sites. This suggested the absence of a ligand at cobalt in CoFeSP in α-position where the dimethylbenzimidazole (dmb base of the cofactor is bound in Cbl in solution. As main species, (dmbCoIII(OH2, (dmbCoII(OH2, and (dmbCoIII(CH3 sites for solution Cbl and CoIII(OH2, CoII(OH2, and CoIII(CH3 sites in CoFeSP-Cbl were identified. Our data support binding of a serine residue from the reductive-activator protein (RACo of CoFeSP to the cobalt ion in the CoFeSP-RACo protein complex that stabilizes Co(II. The absence of an α-ligand at cobalt not only tunes the redox potential of the cobalamin cofactor into the physiological range, but is also important for CoFeSP reactivation.

Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

Science.gov (United States)

Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil; Lidén, Carola; Julander, Anneli; Møller, Per; Johansen, Jeanne Duus

2010-08-01

Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these. This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem.

Biomimetic Nanohydroxyapatite Synthesized With/Without Tris-Buffered Simulated Body Fluid: A Comparative Analysis.

Science.gov (United States)

Rana, Deepti; Wang, Xiumei; Webster, Thomas J; Ramalingam, Murugan

2018-06-01

Nano hydroxyapatite (nHAp) mimics the inorganic phase of hard tissue such as bone and teeth and, thus, has a wide range of clinical applications. The present study reports on the biomimetic synthesis of nHAp with and without Tris-buffered simulated body fluid (SBF) and investigated the role of buffering conditions on nHAp formation. The hypothesis of this study was that the nucleation and growth rate of nHAp may depend on buffering conditions during the precipitation process. The results of this study suggest that both of the above methods effectively synthesized carbonated "bone-like" nHAp. However, an increased incubation period of 8 hrs was necessary for nHAp synthesized using non Tris-buffered SBF as compared to Tris-buffered SBF which synthesized nHAp in just 3 hrs. Interestingly, there was no change in the chemical functionality for both samples. XRD and TGA analysis confirmed that Tris-buffered SBF facilitated more carbonate ion substitution than the non-Tris-buffered SBF approach. Therefore, this study concluded for the first time that the addition of Tris in SBF accelerates nHAp formation with more carbonate ion substitution. Nevertheless, carbonate ion substituted nHAp could also be synthesized using non Tris-buffered SBF, but would require longer incubation periods. This analysis highlights the importance of pH stability in the SBF for biomimetic nHAp synthesis which is useful for the synthesis of nHAp for a wide range of biomedical applications.

Cobalt

International Nuclear Information System (INIS)

Stolyarova, I.A.; Bunakova, N.Yu.

1983-01-01

The neutron-activation method for determining cobalt in rocks, polymetallic and iron ores and rockforming minerals at 2x10 -6 -5x10 -3 % content is developed. Cobalt determination is based on the formation under the effect of thermal neutrons of nuclear reactor of the 60 Co radioactive isotope by the 59 Co (n, γ) 60 Co reaction with radiation energy of the most intensive line of 1333 keV. Cobalt can be determined by the scheme of the multicomponent analysis from the sample with other elements. Co is determined in the solution after separation of all determinable by the scheme elements. The 60 Co intensity is measured by the mUltichannel gamma-spectrometer with Ge(Li)-detector

Microwave assisted synthesis of bis and tris(ω-bromoacetophenones): versatile precursors for novel bis(imidazo[1,2-a]pyridines), bis(imidazo[1,2-a]pyrimidines) and their tris-analogs

Science.gov (United States)

2013-01-01

Background α-Bromination of the side chain of aromatic ketones using NBS in the presence of p-toluenesulfonic acid (p-TsOH) in acetonitrile is very common. However, regioselective bromination of bis and tris(ω-bromoacetophenones) with NBS in the presence of p-TsOH in acetonitrile under microwave irradiation is quite novel. The bis- and tris(ω-bromoacetophenones) are used in synthesis of bis and tris(heterocycles). bis(heterocycles) have received a great deal of attention, because many biologically active natural and synthetic products have molecular symmetry. The use of the pressurized microwave irradiation is very advantageous to many syntheses and provide a large rate enhancement. Results Bis and tris(ω-bromoacetophenones) were obtained as single monobrominated derivatives in a shorter time than the conventional conditions. The results clearly demonstrate the better reactivity and selectivity of NBS/p-TsOH/CH3CN as a brominating mixture under microwave conditions. The reaction of bis and tris(ω-bromoacetophenone) with 2-aminopyridine and 2-aminopyrimidine proceeded smoothly in a mixture of anhydrous ethanol and DMF under reflux or using 300 W/105°C/ 20 min microwave irradiation conditions to afford the corresponding bis(imidazo[1,2-a]pyridine), bis(imidazo[1,2-a]pyrimidine) and tris(imidazo[1,2-a]pyridine) derivatives in moderate to excellent yields. The carbonyl analogue of the targeted bis(imidazopyridines) could be synthesized by the reaction of N,N-dimethyl-N'-(pyridin-2-yl)formimidamide with bis(ω-bromoacetophenone) in refluxing ethanol. The structures of the newly synthesized compounds were confirmed by their spectral data as well as their elemental analyses. Conclusion In conclusion, selective α-bromination of bis- and tris(acetophenones) has been accomplished efficiently utilizing NBS/p-TsOH/CH3CN under microwave irradiation. In addition, a facile synthesis of novel series of bis- and tris(imidazopyridine) and bis(imidazopyrimidine) derivatives

Cobalt release from implants and consumer items and characteristics of cobalt sensitized patients with dermatitis

DEFF Research Database (Denmark)

Thyssen, Jacob Pontoppidan; Menne, Torkil; Liden, Carola

2012-01-01

-containing dental alloys and revised hip implant components.Results. Six of eight dental alloys and 10 of 98 revised hip implant components released cobalt in the cobalt spot test, whereas none of 50 mobile phones gave positive reactions. The clinical relevance of positive cobalt test reactions was difficult......-tested dermatitis patients in an attempt to better understand cobalt allergy.Materials and methods. 19 780 dermatitis patients aged 4-99 years were patch tested with nickel, chromium or cobalt between 1985 and 2010. The cobalt spot test was used to test for cobalt ion release from mobile phones as well as cobalt...

Coordination chemistry of the tiing tris(2-sallicilamidoetil)amina

International Nuclear Information System (INIS)

Fernandez Montalto, A. C.

1997-01-01

Synthesizes a new one tiing hexadented denominated tris (2-salicilamidoetil)amina, starting from the tris (2-aminoetil) amina and three equivalent of fenilo salicilato (salol). The aductos that are formed starting from this tiing with metallic ions of transition di- and trivalent, they are complex of the type LHM and LM respectively, showing a sphere of coordination pseudooctaedrica. The complex Lfe, Lcr and LHCu were synthesized, which were characterized by means of methods spectroscopy and magnetic [es

Detection of pyrrolizidine alkaloids using flow analysis with both acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

International Nuclear Information System (INIS)

Gorman, Bree A.; Barnett, Neil W.; Bos, Richard

2005-01-01

For the first time, analytically useful chemiluminescence was elicited from the reactions of the pyrrolizidine alkaloids. Heliotrine, retronecine, supinine, monocrotaline and echinatine N-oxide yielded chemiluminescence upon reaction with tris(2,2'-bipyridyl)ruthenium(II) whilst lasiocarpine, its N-oxide and supinine elicited light upon reaction with acidic potassium permanganate. Detection limits for heliotrine were 1.25 x 10 -7 M and 9 x 10 -9 M for tris(2,2'-bipyridyl)ruthenium(III) perchlorate with flow injection analysis (FIA) and the silica-immobilised reagent (4-[4-(dichloromethylsilanyl)-butyl]-4'-methyl-2,2'-bipyridine)bis (2,2'-bipyridyl)ruthenium(II) with sequential injection analysis (SIA), respectively. Lasiocarpine was detectable at 1.4 x 10 -7 M using acidic potassium permanganate with FIA. Additionally, the silica-immobilised reagent was optimised with respect to the oxidant (ammonium ceric nitrate) concentration and the aspiration times which afforded a detection limit for codeine of 5 x 10 -10 M using SIA

hermo-Physical and Mechanical Properties of Unsaturated Polyester /Cobalt Ferrite Composites

Directory of Open Access Journals (Sweden)

Lamees Salam Faiq

2017-04-01

Full Text Available Unsaturated polyester was used as a matrix which was filled with different percentages of cobalt ferrite using hand lay-up method. Cobalt ferrite was synthesized using solid state ceramic method with reagent of CoO and Fe2O3. Mechanical properties such tensile strength, Young's modulus and shore D hardness of the composite have been studied. All these properties have increased by 10% with increasing cobalt ferrite contents. Also the thermal properties such thermal conductivity and specific heat capacity are highly increased as the ferrite content increased, while the thermal diffusivity increased by 22 %. On the other hand dielectric strength of composite has been measured which increased by 50% by increasing the cobalt ferrite content.

Interfacial exciplex electroluminescence between diamine derivatives with starburst molecular structure and tris(acetylacetonato)-(mono-phenothroline) thulium

Energy Technology Data Exchange (ETDEWEB)

He Hong [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Li Wenlian [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)], E-mail: wllioel@yahoo.com.cn; Su Zisheng; Chu Bei; Bi Defeng; Chen Yiren; Wang Dan; Su Wenming; Li Bin [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2009-02-20

The authors demonstrate the interfacial exciplex electroluminescence (EL) between tris(acetylacetonato)-(mono-phenothroline) thulium [Tm(AcA){sub 3}phen] and two diamine derivatives with starburst molecular structure- 4,4',4''-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA) and 4,4',4''-tris[3-methyl-pheny(phenyl)-amino]triphenyl-amine (m-MTDATA), both of which have the same ionization potential (IP) (approximately 5.1 eV). When the Tm-complex and the two diamine derivatives are respectively used as the electron accepter and donors, the two EL devices exhibit different exciplex emissions, which verifies our previously reported opinion regarding the effect of the different substitutes on exciplex emission [W.M. Su, W.L. Li, Q. Xin, Z.S. Su, B. Chu, D.F. Bi, H. He, J.H. Niu, Appl. Phys. Lett. 91 (2007) 043508]. When the mixture of the two diamine derivatives is used as a donor, a white EL device with the Commission International de l'Eclairage (CIE) coordinates of (0.277, 0.323) is achieved. The exciplex formation mechanisms of the devices with the two different donors are discussed.

Strong and anisotropic superexchange in the single-molecule magnet (SMM) [MnIII(6)OsIII]3+: promoting SMM behavior through 3d-5d transition metal substitution.

Science.gov (United States)

Hoeke, Veronika; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen; Glaser, Thorsten

2014-01-06

The reaction of the in situ generated trinuclear triplesalen complex [(talent-Bu2)MnIII3(solv)n]3+ with (Ph4P)3[OsIII(CN)6] and NaClO4·H2O affords [MnIII6OsIII](ClO4)3 (= [{(talent-Bu2)MnIII3}2{OsIII(CN)6}](ClO4)3) in the presence of the oxidizing agent [(tacn)2NiIII](ClO4)3 (tacn =1,4,7-triazacyclononane), while the reaction of [(talent-Bu2)MnIII3(solv)n]3+ with K4[OsII(CN)6] and NaClO4·H2O yields [MnIII6OsII](ClO4)2 under an argon atmosphere. The molecular structure of [MnIII6OsIII]3+ as determined by single-crystal X-ray diffraction is closely related to the already published [MnIII6Mc]3+ complexes (Mc = CrIII, FeIII, CoIII, MnIII). The half-wave potential of the OsIII/OsII couple is E1/2 = 0.07 V vs Fc+/Fc. The FT-IR and electronic absorption spectra of [MnIII6OsII]2+ and [MnIII6OsIII]3+ exhibit distinct features of dicationic and tricationic [MnIII6Mc]n+ complexes, respectively. The dc magnetic data (μeff vs T, M vs B, and VTVH) of [MnIII6OsII]2+ are successfully simulated by a full-matrix diagonalization of a spin-Hamiltonian including isotropic exchange, zero-field splitting with full consideration of the relative orientation of the D-tensors, and Zeeman interaction, indicating antiferromagnetic MnIII–MnIII interactions within the trinuclear triplesalen subunits (JMn–Mn(1) = −(0.53 ± 0.01) cm–1, Ĥex = −2∑iSMM [MnIII6OsIII]3+ compared to the 3d analogue [MnIII6FeIII]3+ due to the stronger and anisotropic Mc–MnIII exchange interaction.

Cobalt-Catalyzed C(sp(2))-H Borylation: Mechanistic Insights Inspire Catalyst Design.

Science.gov (United States)

Obligacion, Jennifer V; Semproni, Scott P; Pappas, Iraklis; Chirik, Paul J

2016-08-24

A comprehensive study into the mechanism of bis(phosphino)pyridine (PNP) cobalt-catalyzed C-H borylation of 2,6-lutidine using B2Pin2 (Pin = pinacolate) has been conducted. The experimentally observed rate law, deuterium kinetic isotope effects, and identification of the catalyst resting state support turnover limiting C-H activation from a fully characterized cobalt(I) boryl intermediate. Monitoring the catalytic reaction as a function of time revealed that borylation of the 4-position of the pincer in the cobalt catalyst was faster than arene borylation. Cyclic voltammetry established the electron withdrawing influence of 4-BPin, which slows the rate of C-H oxidative addition and hence overall catalytic turnover. This mechanistic insight inspired the next generation of 4-substituted PNP cobalt catalysts with electron donating and sterically blocking methyl and pyrrolidinyl substituents that exhibited increased activity for the C-H borylation of unactivated arenes. The rationally designed catalysts promote effective turnover with stoichiometric quantities of arene substrate and B2Pin2. Kinetic studies on the improved catalyst, 4-(H)2BPin, established a change in turnover limiting step from C-H oxidative addition to C-B reductive elimination. The iridium congener of the optimized cobalt catalyst, 6-(H)2BPin, was prepared and crystallographically characterized and proved inactive for C-H borylation, a result of the high kinetic barrier for reductive elimination from octahedral Ir(III) complexes.

Exploration of spectroscopic properties of solvated tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III)red hybrid organic complex for solution processed OLEDs and displays

Energy Technology Data Exchange (ETDEWEB)

Chitnis, Dipti [Department of Physics, RTM Nagpur University, Nagpur 440033 (India); Thejokalyani, N., E-mail: thejokalyani@rediffmail.com [Department of Applied Physics, Laxminarayan Institute of Technology, Nagpur 440033 (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India)

2017-05-15

In order to explore the spectroscopic properties of a novel europium activated hybrid organic tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III), Eu(TTA){sub 3}bipy phosphor in various solvents at different pH and molar concentrations, UV–vis optical absorption and photoluminescence spectra were carried out. With a variation in the solvent from basic (chloroform, toluene, tetrahydrofuran) to acidic (acetic acid, formic acid) media, staggering differences in optical absorptions and optical densities were noticed with hypsochromic shift in the absorption peaks. The optical density was found to be maximum for the complex with pH= 7.0 and the intensity as well as optical density gradually decreased when pH is lowered to 6.0 or raised to 8.0 (at an interval of 0.5), proving that the complex is pH sensitive. It's optical energy gap and stokes shift values in various organic solvents were also calculated on the basis of Lippert-Mataga plot. The exploration of spectroscopic properties of solvated Eu(TTA){sub 3}bipy complex demonstrates its prospective for solution processed OLEDs and display devices. - Graphical abstract: Pictorial depiction of photoluminescence in solvated Eu(TTA){sub 3}bipy complex under UV light.

Radiation regression patterns after cobalt plaque insertion for retinoblastoma

International Nuclear Information System (INIS)

Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

1983-01-01

An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy)

Radiation regression patterns after cobalt plaque insertion for retinoblastoma

Energy Technology Data Exchange (ETDEWEB)

Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

1983-08-01

An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy).

Magnetic anisotropy of cobalt nanoparticle 2D arrays grown on corrugated MnF{sub 2}(1 1 0) and CaF{sub 2}(1 1 0) surfaces

Energy Technology Data Exchange (ETDEWEB)

Baranov, D.A., E-mail: dbaranov@mail.ioffe.ru [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 26 Polytechnicheskaya str., St. Petersburg 194021 (Russian Federation); Krichevtsov, B.B.; Gastev, S.V.; Banschikov, A.G.; Fedorov, V.V. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 26 Polytechnicheskaya str., St. Petersburg 194021 (Russian Federation); Koshmak, K.V. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 26 Polytechnicheskaya str., St. Petersburg 194021 (Russian Federation); Dipartimento di Ingegneria dei Materiali e dell’Ambiente, Università di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena (Italy); Suturin, S.M.; Sokolov, N.S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 26 Polytechnicheskaya str., St. Petersburg 194021 (Russian Federation)

2013-02-15

Cobalt nanoparticle 2D arrays with different effective thicknesses of cobalt layer (2 nm < d{sub eff} < 10 nm) were grown by molecular beam epitaxy on CaF{sub 2}(1 1 0)/Si(0 0 1) and MnF{sub 2}(1 1 0)/CaF{sub 2}(1 1 0)/Si(0 0 1) substrates with corrugated morphology of the surface. Surface morphology analysis showed that for effective thickness of cobalt layer d{sub eff} = 5 nm the lateral dimensions of cobalt islands are about 5–10 nm and the distances between the islands differs in a half along and across the grooves. In both types of the heterostructures the shape of hysteresis loops measured by LMOKE depend on orientation of in-plane magnetic field relative to the direction of the grooves. The azimuthal dependence of coercive field H{sub c} in Co/CaF{sub 2}(1 1 0)/Si(0 0 1) structures corresponds to Stoner–Wohlfarth model's predictions, which takes into account the anisotropy of individual particles. In contrast to that, in Co/MnF{sub 2}(1 1 0)/CaF{sub 2}(1 1 0)/Si(0 0 1) structures these dependences are analogous to those predicted by the model based on account of magnetic–dipole interaction between particles which are placed in chains (chain-of-spheres-model). Possible explanations of the difference in magnetic anisotropy are suggested.

Interaction of zinc and cobalt with dipeptides and their DNA binding ...

Indian Academy of Sciences (India)

Unknown

Concentrated CT DNA stock solutions were pre- pared in tris .... the SH, NH and NH2 hydrogen exchange with D2O the changes in ... which is an index of the interaction between the. DNA and ... Since ESI-MS is a powerful new approach for.

Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) cobalt hydride for Kumada coupling reactions.

Science.gov (United States)

Qi, Xinghao; Sun, Hongjian; Li, Xiaoyan; Fuhr, Olaf; Fenske, Dieter

2018-02-20

The electron-rich silylene Co(i) chloride 5 was obtained through the reaction of CoCl(PMe 3 ) 3 with chlorosilylene. Complex 5 reacted with 1,3-siladiazole HSiMe(NCH 2 PPh 2 ) 2 C 6 H 4 to give the silylene Co(iii) hydride 6 through chelate-assisted Si-H activation. To the best of our knowledge, complex 6 is the first example of Co(iii) hydride supported by N-heterocyclic silylene. Complexes 5 and 6 were fully characterized by spectroscopic methods and X-ray diffraction analysis. Complex 6 was used as an efficient precatalyst for Kumada cross-coupling reactions. Compared with the related complex 3 supported by only trimethylphosphine, complex 6 as a catalyst supported by both chlorosilylene and trimethylphosphine exhibits a more efficient performance for the Kumada cross-coupling reactions. A novel catalytic radical mechanism was suggested and experimentally verified. As an intermediate silylene cobalt(ii) chloride 6d was isolated and structurally characterized.

File list: Pol.NoD.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available Pol.NoD.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III No des...cription http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.NoD.50.RNA_polymerase_III.AllCell.bed ...

File list: Pol.NoD.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available Pol.NoD.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III No des...cription http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.NoD.10.RNA_polymerase_III.AllCell.bed ...

File list: Pol.NoD.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available Pol.NoD.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III No des...cription http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.NoD.20.RNA_polymerase_III.AllCell.bed ...

H₃O_2-, O₂^2- and O₂•- bridging ligands in cobalt(III) complexes of an acyclic phenolate-hinged dinucleating ligand

DEFF Research Database (Denmark)

Ghiladi, Morten; Gomez, Jonnes T.; Hazell, A.

2003-01-01

The dicobalt(III) complex, [Co2(bpbp)(μ-H3O2)2](ClO4)3 (bpbp− = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-tert-butylphenolate), obtained by reaction of cobalt(II) perchlorate with Hbpbp under ambient conditions contains two μ-H3O2− bridging ligands. The H-bonded O⋯O distances in this motif are 2...

High performance liquid chromatographic determination of vanadium in crude oils and cobalt and iron in pharmaceutical preparations

International Nuclear Information System (INIS)

Khuhawar, M.Y.; Lanjwani, S.N.; Khaskhely, G.Q.

1993-01-01

High performance liquid Chromatographic (HPLC) method has ben developed for the determination of vanadium in crude oils, based on acid decomposition of oils, followed by complexation with bis (salicylaldehyde) tetramethyl ethylenediamine (H2SA2Ten). The complex is extracted in organic phase and is separated from copper and nickel using normal phase HPLC column. Detection is achieved using spectrophtmetric detector. The vanadium in oil is obtained at sub microgram/g level. Similarly cobalt(II), cobalt(III) and iron(II) are separated on reversed phase HPLC column. Pre column derivatization is used to develop HPLC method for the determination of cobalt and iron in pharmaceutical preparations. Finally results are compared using atomic absorption spectrometer. (author)

Structural, kinetic, and thermodynamic characterization of the interconverting isomers of MS-325, a gadolinium(III)-based magnetic resonance angiography contrast agent.

Science.gov (United States)

Tyeklar, Zoltan; Dunham, Stephen U; Midelfort, Katarina; Scott, Daniel M; Sajiki, Hirano; Ong, Karen; Lauffer, Randall B; Caravan, Peter; McMurry, Thomas J

2007-08-06

The amphiphilic gadolinium complex MS-325 ((trisodium-{(2-(R)-[(4,4-diphenylcyclohexyl) phosphonooxymethyl] diethylenetriaminepentaacetato) (aquo)gadolinium(III)}) is a contrast agent for magnetic resonance angiography (MRA). MS-325 comprises a GdDTPA core with an appended phosphodiester moiety linked to a diphenylcyclohexyl group to facilitate noncovalent binding to serum albumin and extension of the plasma half-life in vivo. The chiral DTPA ligand (R) was derived from L-serine, and upon complexation with gadolinium, forms two interconvertible diastereomers, denoted herein as isomers A and B. X-ray crystallography of the tris(ethylenediamine)cobalt(III) salt derivative of isomer A revealed a structure in the polar acentric space group P32. The structure consisted of three independent molecules of the gadolinium complex in the asymmetric unit along with three Delta-[Co(en)3]3+ cations, and it represents an unusual example of spontaneous Pasteur resolution of the cobalt cation. The geometry of the coordination core was best described as a distorted trigonal prism, and the final R factor was 5.6%. The configuration of the chiral central nitrogen of the DTPA core was S. The Gd-water (2.47-2.48 A), the Gd-acetate oxygens (2.34-2.42 A), and the Gd-N bond distances (central N, 2.59-2.63 A; terminal N, 2.74-2.80 A) were similar to other reported GdDTPA structures. The structurally characterized single crystal was one of two interconvertable diastereomers (isomers A and B) that equilibrated to a ratio of 1.81 to 1 at pH 7.4 and were separable at elevated pH by ion-exchange chromatography. The rate of isomerization was highly pH dependent: k1 = (1.45 +/- 0.08) x 102[H+] + (4.16 +/- 0.30) x 105[H+]2; k-1 = (2.57 +/- 0.17) x 102[H+] + (7.54 +/- 0.60) x 105[H+]2.

Detection of pyrrolizidine alkaloids using flow analysis with both acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

Energy Technology Data Exchange (ETDEWEB)

Gorman, Bree A. [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia); Barnett, Neil W. [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia)]. E-mail: barnie@deakin.edu.au; Bos, Richard [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia)

2005-06-13

For the first time, analytically useful chemiluminescence was elicited from the reactions of the pyrrolizidine alkaloids. Heliotrine, retronecine, supinine, monocrotaline and echinatine N-oxide yielded chemiluminescence upon reaction with tris(2,2'-bipyridyl)ruthenium(II) whilst lasiocarpine, its N-oxide and supinine elicited light upon reaction with acidic potassium permanganate. Detection limits for heliotrine were 1.25 x 10{sup -7} M and 9 x 10{sup -9} M for tris(2,2'-bipyridyl)ruthenium(III) perchlorate with flow injection analysis (FIA) and the silica-immobilised reagent (4-[4-(dichloromethylsilanyl)-butyl]-4'-methyl-2,2'-bipyridine)bis (2,2'-bipyridyl)ruthenium(II) with sequential injection analysis (SIA), respectively. Lasiocarpine was detectable at 1.4 x 10{sup -7} M using acidic potassium permanganate with FIA. Additionally, the silica-immobilised reagent was optimised with respect to the oxidant (ammonium ceric nitrate) concentration and the aspiration times which afforded a detection limit for codeine of 5 x 10{sup -10} M using SIA.

Trace cobalt speciation in bacteria and at enzymic active sites using emission Moessbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kamnev, A.A.; Antonyuk, L.P.; Smirnova, V.E.; Serebrennikova, O.B. [Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov (Russian Federation); Kulikov, L.A.; Perfiliev, Yu.D. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, Moscow State University (Russian Federation)

2002-02-01

{sup 57}Co emission Moessbauer spectroscopy (EMS) allows the chemical state of cobalt, as influenced by its coordination environment, to be monitored in biological samples at its physiological (trace) concentrations. To draw attention to EMS as a valuable tool for speciation of cobalt in biocomplexes, the process of cobalt(II) metabolism in cells of the plant growth-promoting rhizobacterium Azospirillum brasilense Sp245 was investigated using EMS of {sup 57}Co{sup II}-doped bacterial cells. EMS measurements also showed {sup 57}Co{sup II}-activated glutamine synthetase (GS, a key enzyme of nitrogen metabolism, isolated from this bacterium) to have two different cobalt(II) forms at its active sites, in agreement with data available on other bacterial GSs. Chemical after-effects following electron capture by the nucleus of the parent {sup 57}Co{sup II} during the {sup 57}Co{yields}{sup 57}Fe transition, which contribute to the formation of a stabilised daughter {sup 57}Fe{sup III} component along with the nucleogenic {sup 57}Fe{sup II} forms, are also briefly considered. (orig.)

Synthesis, multi-nonlinear dielectric resonance and electromagnetic absorption properties of hcp-cobalt particles

International Nuclear Information System (INIS)

Wen, Shulai; Liu, Ying; Zhao, Xiuchen; Cheng, Jingwei; Li, Hong

2014-01-01

Hcp-cobalt particles were successfully prepared by a liquid phase reduction method, and the microstructure, static magnetic properties, electromagnetic and microwave absorption properties of the cobalt particles with irregular shape were investigated in detail. The measured results indicate that the saturation magnetization was less than that of hcp-Co single crystals, and the coercivity was larger than that of bulk cobalt crystal. The permittivity presents multi-nonlinear dielectric resonance, which may result from the irregular shape containing parts of cutting angle of dodecahedron of cobalt particles. The real part of permeability decreases with the frequency, and the imaginary part has a wide resonant peak. The paraffin-based composite containing 70 wt% cobalt particles possessed strong absorption characteristics with a minimum RL of −38.97 dB at 10.81 GHz and an absorption band with RL under −10 dB from 8.72 to 13.26 GHz when the thickness is 1.8 mm, which exhibits excellent microwave absorption in middle and high frequency. The architectural design of material morphologies is important for improving microwave absorption properties toward future application. - Highlights: • Hcp-cobalt particles were prepared by a liquid phase reduction method. • The saturation magnetization was less than that of hcp-Co single crystals. • The permittivity presents multi-nonlinear dielectric resonance. • The real part of permeability decreases with frequency, and the imaginary part presents a wide resonant peak. • The paraffin-based composite possessed a minimum RL of −38.97 dB at 10.81 GHz

Design, synthesis and in vitro evaluation on glucosamine-6P synthase of aromatic analogs of 2-Aminohexitols-6P

Energy Technology Data Exchange (ETDEWEB)

Dias, Danielle F.; Alves, Ricardo J., E-mail: ricardodylan@farmacia.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Faculdade de Farmacia; Roux, Celine; Durand, Philippe; Iorga, Bogdan; Badet-Denisot, Marie A.; Badet, Bernard [Centre National de la Recherche Scientifique (CNRS), Gif-sur-Yvette (France). Inst. de Chimie des Substances Naturelles

2010-07-01

The aminosugars are very important structural components of bacterial and fungi cell walls. Glucosamine-6-phosphate synthase (GlmS), which catalyses the first step of the aminosugar biosynthetic pathway i.e. the formation of D-glucosamine-6-phosphate from D-fructose-6-phosphate, is therefore an interesting target in the fight against microorganisms. In this work is described the synthesis of aromatic analogs of 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP) and its epimer 2-amino-2-deoxy-D-manitol-6-phosphate (ADMP), two important inhibitors of GlmS. The aromatic analogs displayed modest inhibitory activity against GlmS, with IC{sub 50} in the mmol L{sup -1} range. (author)

Passivation and corrosion behaviours of cobalt and cobalt-chromium-molybdenum alloy

International Nuclear Information System (INIS)

Metikos-Hukovic, M.; Babic, R.

2007-01-01

Passivation and corrosion behaviour of the cobalt and cobalt-base alloy Co30Cr6Mo was studied in a simulated physiological solution containing chloride and bicarbonate ions and with pH of 6.8. The oxido-reduction processes included solid state transformations occurring at the cobalt/electrolyte interface are interpreted using theories of surface electrochemistry. The dissolution of cobalt is significantly suppressed by alloying it with chromium and molybdenum, since the alloy exhibited 'chromium like' passivity. The structural and protective properties of passive oxide films formed spontaneously at the open circuit potential or during the anodic polarization were studied using electrochemical impedance spectroscopy in the wide frequency range

Luminescent amine sensor based on europium(III) chelate.

Science.gov (United States)

Petrochenkova, Nataliya V; Mirochnik, Anatolii G; Emelina, Tatyana B; Sergeev, Alexander A; Leonov, Andrei A; Voznesenskii, Sergey S

2018-07-05

The effect of methylamine vapor on luminescence of Eu(III) tris-benzoylacetonate (I) immobilized in thin-layer chromatography plates has been investigated. It has been revealed that interaction of I with analyte vapor results in increase of the intensity of Eu(III) luminescence. The mechanism of the effect of methylamine vapors on intensification of the Eu(III) luminescence has been suggested using the data of IR spectroscopy and quantum chemistry calculations. The mechanism of luminescence sensitization consists in bonding of an analyte molecule with a water molecule into the coordination sphere of Eu(III). As a result, the bond of a water molecule with the luminescence centre weakens, rigid structural fragment including europium ion, water and methylamine molecules forms. The presence of such fragment must naturally promote decrease of influence of OH-vibrations on luminescence of the complex I. Copyright © 2018 Elsevier B.V. All rights reserved.

Tris(2-(1 H -pyrazol-1-yl)pyridine)cobalt(III) as p-Type Dopant for Organic Semiconductors and Its Application in Highly Efficient Solid-State Dye-Sensitized Solar Cells

KAUST Repository

Burschka, Julian

2011-11-16

Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co(III) complexes as p-type dopants for triarylamine-based hole conductors such as spiro-MeOTAD and their application in solid-state dye-sensitized solar cells (ssDSCs). We show that the proposed compounds fulfill the requirements for this application and that the discussed strategy is promising for tuning the conductivity of spiro-MeOTAD in ssDSCs, without having to rely on the commonly employed photo-doping. By using a recently developed high molar extinction coefficient organic D-π-A sensitizer and p-doped spiro-MeOTAD as hole conductor, we achieved a record power conversion efficiency of 7.2%, measured under standard solar conditions (AM1.5G, 100 mW cm -2). We expect these promising new dopants to find widespread applications in organic electronics in general and photovoltaics in particular. © 2011 American Chemical Society.

Introduction dosimetric data of cobalt-60 unit in planning new Win-PTL- 3D

International Nuclear Information System (INIS)

Gonzalez Perez, Yelina; Rodriguez Zayas, Michael; Perez Guevara, Adrian; Sanchez Zamora, Luis; Reyes Gonzalez, Tommy; Sola Rodriguez, Yeline; Caballero, Roberto; Cruz Marcane, Viviana

2009-01-01

3D planning is based on the individual and image reconstruction formation of fields, allowing better absorption of dose volume White minimizing damage to surrounding healthy tissue. During the clinical implementation of the Win-PLT software includes validation from the implementation of dosimetric acceptance tests through a series of precise experimental measurements, reflecting different clinical situations (test cases). For the commissioning characterized the photon beam Cobalt Unit 60, taking measurements with a set consisting of a phantom dosimetric automatic ionization chambers and electrometer Tandem. The measured data are used to power the TPS through WINCOM auxiliary program that lets you adjust a number of parameters to model the photon beam. This adjustment is made by comparing the PDD curves and profiles of experimental data with modeled data. The test cases performed are in compliance with the requirements proposed in the geometric of the AAPM TG55. The modeling of beam dosimetry data was successful, since the discrepancies were within the criteria TRS-430. The cases involved events where points near the edge of the field and in the presence of blocking a discrepancy outside the tolerance, suggesting not to use these items for purposes of limitation. Win TPS-PLT is suitable for clinical use with the photon beam Cobalt Unit 60, backed by the reliability that dropped on the results of beam modeling and verification of dosimetric calculations. (Author)

CP/MAS 13C NMR characterization of the isomeric states and intermolecular packing in tris(8-hydroxyquinoline) aluminum(III) (Alq3).

Science.gov (United States)

Kaji, Hironori; Kusaka, Yasunari; Onoyama, Goro; Horii, Fumitaka

2006-04-05

The isomeric states and intermolecular packing of tris(8-hydroxyquinoline) aluminum(III) (Alq(3)) in the alpha-, gamma-, and delta-crystalline forms and in the amorphous state, which are important for understanding the light-emitting and electron-transport properties, have been analyzed by CP/MAS (13)C NMR. This simple NMR experiment shows that the isomeric state of alpha- and amorphous Alq(3) is meridional, whereas that of gamma- and delta-Alq(3) is facial. In the amorphous Alq(3), the inclusion of facial isomers has been under debate. Our experiments show that meridional isomers are dominant in the amorphous Alq(3), although the existence of facial isomers cannot be completely denied. The local structure of amorphous Alq(3) is similar to that of alpha-Alq(3) and is significantly different from those of gamma- and delta-Alq(3). Among these Alq(3) samples, the effect of intermolecular interaction is not found only for gamma-Alq(3). This finding can explain the good solvent solubility of gamma-Alq(3), compared with the other crystalline forms. It is also shown that the structures are locally disordered not only for amorphous Alq(3) but also for alpha-Alq(3), although clear X-ray diffraction peaks are observed for alpha-Alq(3). In contrast, the local structures of gamma- and delta-Alq(3) are well defined. A clear relation is found between the spectral patterns of CP/MAS (13)C NMR and the fluorescence wavelengths; the samples, which consist of facial isomers, show blue-shifted fluorescence compared with those of meridionals.

Spectroscopic, potentiometric and theoretical studies on the binding properties of a novel tripodal polycatechol-imine ligand towards iron(III)

Science.gov (United States)

Kanungo, B. K.; Sahoo, Suban K.; Baral, Minati

2008-12-01

A novel multidentate tripodal ligand, cis, cis-1,3,5-tris[(2,3-dihydroxybenzylidene)aminomethyl]cyclohexane (TDBAC, L) containing one catechol unit in each arms of a tripodal amine, cis, cis-1,3,5-tris(aminomethyl)cyclohexane was investigated as a chelator for iron(III) through potentiometric and spectrophotometric methods in an aqueous medium of 0.1N ionic strength and 25 ± 1 °C as well as in ethanol by continuous variation method. From pH metric in water, three protonation constants characterized for the three-hydroxyl groups of the catechol units at ortho were used as input data to evaluate the stability constants of the complexes. Formation of monomeric complexes FeLH 3, FeLH 2, FeLH and FeL were depicted. In ethanol, formation of complexes FeL, Fe 2L and Fe 3L were characterized. Structures of the complexes were explained by using the experimental evidences and predicted through molecular modeling calculations. The ligand showed potential to coordinate iron(III) through three imine nitrogens and three catecholic oxygens at ortho to form a tris(iminocatecholate) type complex.

Tris(O-cyclo-hexyl dithio-carbonato-κS)anti-mony(III).

Science.gov (United States)

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2008-12-10

In the mol-ecule of the title compound, [Sb(C(7)H(11)OS(2))(3)], the anti-mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination.

Elicitation threshold of cobalt chloride

DEFF Research Database (Denmark)

Fischer, Louise A; Johansen, Jeanne D; Voelund, Aage

2016-01-01

: On the basis of five included studies, the ED10 values of aqueous cobalt chloride ranged between 0.0663 and 1.95 µg cobalt/cm(2), corresponding to 30.8-259 ppm. CONCLUSIONS: Our analysis provides an overview of the doses of cobalt that are required to elicit allergic cobalt contactdermatitis in sensitized...

Comparative computational study of interaction of C60-fullerene and tris-malonyl-C60-fullerene isomers with lipid bilayer: relation to their antioxidant effect.

Directory of Open Access Journals (Sweden)

Marine E Bozdaganyan

Full Text Available Oxidative stress induced by excessive production of reactive oxygen species (ROS has been implicated in the etiology of many human diseases. It has been reported that fullerenes and some of their derivatives-carboxyfullerenes-exhibits a strong free radical scavenging capacity. The permeation of C60-fullerene and its amphiphilic derivatives-C3-tris-malonic-C60-fullerene (C3 and D3-tris-malonyl-C60-fullerene (D3-through a lipid bilayer mimicking the eukaryotic cell membrane was studied using molecular dynamics (MD simulations. The free energy profiles along the normal to the bilayer composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC for C60, C3 and D3 were calculated. We found that C60 molecules alone or in clusters spontaneously translocate to the hydrophobic core of the membrane and stay inside the bilayer during the whole period of simulation time. The incorporation of cluster of fullerenes inside the bilayer changes properties of the bilayer and leads to its deformation. In simulations of the tris-malonic fullerenes we discovered that both isomers, C3 and D3, adsorb at the surface of the bilayer but only C3 tends to be buried in the area of the lipid headgroups forming hydrophobic contacts with the lipid tails. We hypothesize that such position has implications for ROS scavenging mechanism in the specific cell compartments.

Magnetic and resonance properties of ferrihydrite nanoparticles doped with cobalt

Science.gov (United States)

Stolyar, S. V.; Yaroslavtsev, R. N.; Iskhakov, R. S.; Bayukov, O. A.; Balaev, D. A.; Dubrovskii, A. A.; Krasikov, A. A.; Ladygina, V. P.; Vorotynov, A. M.; Volochaev, M. N.

2017-03-01

Powders of undoped ferrihydrite nanoparticles and ferrihydrite nanoparticles doped with cobalt in the ratio of 5: 1 have been prepared by hydrolysis of 3 d-metal salts. It has been shown using Mössbauer spectroscopy that cobalt is uniformly distributed over characteristic crystal-chemical positions of iron ions. The blocking temperatures of ferrihydrite nanoparticles have been determined. The nanoparticle sizes, magnetizations, surface anisotropy constants, and bulk anisotropy constants have been estimated. The doping of ferrihydrite nanoparticles with cobalt leads to a significant increase in the anisotropy constant of a nanoparticle and to the formation of surface rotational anisotropy with the surface anisotropy constant K u = 1.6 × 10-3 erg/cm2.

Structural and magnetic properties of the products of the transformation of ferrihydrite: Effect of cobalt dications

Energy Technology Data Exchange (ETDEWEB)

Camacho, K.I. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Pariona, N. [Red de Estudios Moleculares Avanzados, Instituto de Ecología A.C., Carretera Antigua a Coatepec 351, El Haya, 91070 Xalapa, Veracruz (Mexico); Martinez, A.I., E-mail: arturo.martinez@cinvestav.edu.mx [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Río de Janeiro 22290-180 (Brazil); Herrera-Trejo, M. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Perry, Dale L. [Mailstop 70A1150, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

2017-05-01

The effect of cobalt dications on the transformation of 2-line ferrihydrite (2LF) has been studied. The products of the transformation reaction were characterized by X-ray diffraction, Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), magnetometry, and first-order reversal curve (FORC) diagrams. It was found that the concentration of cobalt dications plays an important role on the structural and magnetic properties of the products; i.e., for low cobalt concentrations, cobalt-substituted hematite is formed, while higher concentrations promote the formation of cobalt-substituted magnetite. Structural results revealed that formation of other iron oxide polymorphs is avoided and residual 2LF is always present in the final products. In this way, hematite/2LF and magnetite/2LF nanocomposites were formed. For all the samples, magnetic measurements yielded non-saturated hysteresis loops at a maximum field of 12 kOe. For cobalt-substituted hematite/2LF samples, FORC diagrams revealed the presence of multiple single-domain (SD) components which generate interaction coupling between SD with low and high coercivity. Moreover, for cobalt-substituted magnetite/2LF samples, the FORC diagrams revealed the components of wasp-waist hysteresis loops which consist of mixtures of SD and superparamagnetic particles. One of the goals of the present study is the rigorous, experimental documentation of ferrihydrite/hematite mixtures as a function of reaction conditions for use as analytical standards research. - Highlights: • Co(II) may stabilize ferrihydrite against transformation to more crystalline oxides. • The transformation is strongly dependent on the Co(II)/Fe(III) atomic ratio. • Cobalt-substituted hematite and cobalt-substituted magnetite were the products. • FORC diagrams identified the interaction coupling between single-domains.

Structural and magnetic properties of the products of the transformation of ferrihydrite: Effect of cobalt dications

International Nuclear Information System (INIS)

Camacho, K.I.; Pariona, N.; Martinez, A.I.; Baggio-Saitovitch, E.; Herrera-Trejo, M.; Perry, Dale L.

2017-01-01

The effect of cobalt dications on the transformation of 2-line ferrihydrite (2LF) has been studied. The products of the transformation reaction were characterized by X-ray diffraction, Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), magnetometry, and first-order reversal curve (FORC) diagrams. It was found that the concentration of cobalt dications plays an important role on the structural and magnetic properties of the products; i.e., for low cobalt concentrations, cobalt-substituted hematite is formed, while higher concentrations promote the formation of cobalt-substituted magnetite. Structural results revealed that formation of other iron oxide polymorphs is avoided and residual 2LF is always present in the final products. In this way, hematite/2LF and magnetite/2LF nanocomposites were formed. For all the samples, magnetic measurements yielded non-saturated hysteresis loops at a maximum field of 12 kOe. For cobalt-substituted hematite/2LF samples, FORC diagrams revealed the presence of multiple single-domain (SD) components which generate interaction coupling between SD with low and high coercivity. Moreover, for cobalt-substituted magnetite/2LF samples, the FORC diagrams revealed the components of wasp-waist hysteresis loops which consist of mixtures of SD and superparamagnetic particles. One of the goals of the present study is the rigorous, experimental documentation of ferrihydrite/hematite mixtures as a function of reaction conditions for use as analytical standards research. - Highlights: • Co(II) may stabilize ferrihydrite against transformation to more crystalline oxides. • The transformation is strongly dependent on the Co(II)/Fe(III) atomic ratio. • Cobalt-substituted hematite and cobalt-substituted magnetite were the products. • FORC diagrams identified the interaction coupling between single-domains.

Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway

DEFF Research Database (Denmark)

Wegeberg, Christina; Lauritsen, Frants R.; Frandsen, Cathrine

2018-01-01

The reactivity of [FeIII(tpena)]2+ (tpena=N,N,N'-tris(2-pyridylmethyl)ethylenediamine-N'-acetate) as a catalyst for oxidation reactions depends on its ratio to the terminal oxidant H2O2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1)catalysed H2O2...

N,N,N-Tris(diphenylphosphorylmethylamine

Directory of Open Access Journals (Sweden)

Olaf Walter

2017-10-01

Full Text Available The structure of N,N,N-tris(diphenylphosphorylmethylamine, C39H36NO3P3, at 103 K has monoclinic (P21/c symmetry. Two molecules, each with pseudo-threefold rotation symmetry, crystallize in the asymmetric unit of the monoclinic unit cell. The compound acts as ligand for the stabilization of metal ions with flexible coordination enabling three- or fourfold coordination.

Field-Induced Single-Ion Magnet Behaviour in Two New Cobalt(II Coordination Polymers with 2,4,6-Tris(4-pyridyl-1,3,5-triazine

Directory of Open Access Journals (Sweden)

Dong Shao

2017-12-01

Full Text Available We herein reported the syntheses, crystal structures, and magnetic properties of a two-dimensional coordination polymer {[CoII(TPT2/3(H2O4][CH3COO]2·(H2O4}n (1 and a chain compound {[CoII(TPT2(CHOO2(H2O2]}n (2 based on the 2,4,6-Tris(4-pyridyl-1,3,5-triazine (TPT ligand. Structure analyses showed that complex 1 had a cationic hexagonal framework structure, while 2 was a neutral zig-zag chain structure with different distorted octahedral coordination environments. Magnetic measurements revealed that both complexes exhibit large easy-plane magnetic anisotropy with the zero-field splitting parameter D = 47.7 and 62.1 cm−1 for 1 and 2, respectively. This magnetic anisotropy leads to the field-induced slow magnetic relaxation behaviour. However, their magnetic dynamics are quite different; while complex 1 experienced a dominating thermally activated Orbach relaxation at the whole measured temperature region, 2 exhibited multiple relaxation pathways involving direct, Raman, and quantum tunneling (QTM processes at low temperatures and Orbach relaxation at high temperatures. The present complexes enlarge the family of framework-based single-ion magnets (SIMs and highlight the significance of the structural dimensionality to the final magnetic properties.

Synthesis and photophysical properties of aluminium tris-(4-morpholine-8-hydroxyquinoline).

Science.gov (United States)

Omar, Walaa A E

2013-11-01

Aluminium tris(4-morpholinyl-8-hydroxyquinoline) has been synthesized and characterized. The photoluminescence measurements showed that the new derivative is blue shifted and has relative photoluminescence quantum yield two times higher compared to the pristine Al tris(8-hydroxyquinoline). Deferential scanning colorimetric studies revealed that the newly synthesized Alq3 derivative in this work is amorphous material with the highest transition glass temperature value among the reported amorphous Alq3 derivatives.

Evidence of interface exchange magnetism in self-assembled cobalt-fullerene nanocomposites exposed to air

Czech Academy of Sciences Publication Activity Database

Lavrentiev, Vasyl; Stupakov, Alexandr; Lavrentieva, Inna; Motylenko, M.; Barchuk, M.; Rafaja, D.

2017-01-01

Roč. 28, č. 12 (2017), č. článku 125704. ISSN 0957-4484 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : fullerene * cobalt clusters * cobalt oxide * nanocomposite * interface exchange magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism; JB - Sensors, Measurment, Regulation (FZU-D) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Electrical and electronic engineering (FZU-D) Impact factor: 3.440, year: 2016

Redetermination of dicerium(III) tris­(sulfate) tetra­hydrate

OpenAIRE

Xu, Xin

2007-01-01

Ce2(SO4)3(H2O)4 was obtained hydrothermally from an aqueous solution of cerium(III) oxide, trimethylamine and sulfuric acid. The precision of the structure determination has been significantly improved compared with the previous result [Dereigne (1972). Bull. Soc. Fr. Mineral. Cristallogr. 95, 269–280]. The coordination about the two Ce atoms is achieved by seven and six bridging O atoms from sulfate anions. Each S atom makes four S—O—Ce linkages through bridging O atoms. Th...

fac-Tris(pyridine-2-carboxylato-κ2N,Ocobalt(III

Directory of Open Access Journals (Sweden)

Irina A. Golenia

2011-11-01

Full Text Available In the title compound, [Co(C6H4NO23], the CoIII ion lies on a threefold rotation axis and is in a distorted octahedral environment defined by three N and three O donor atoms from three fac-disposed pyridine-2-carboxylate ligands. The ligands are coordinated in a chelate fashion, forming three five-membered rings. In the crystal, translationally related complex molecules are organized into columns along [001] via C—H...O hydrogen bonds.

The effect of organics on the sorption of cobalt by glacial sand in laboratory batch experiments

International Nuclear Information System (INIS)

Haigh, D.G.; Williams, G.M.; Hooker, P.J.; Ross, C.A.M.; Allen, M.R.; Warwick, P.

1989-01-01

Acetate, EDTA and organic compounds naturally present in groundwater at the Drigg in situ radionuclide migration experimental site, have been studied to assess their effect on the sorption of cobalt by glacial sand in a series of batch experiments. Removing 56% of the natural organic material from the grounwater with DEAE cellulose increased the distribution ratio (R d ) of cobalt by a factor of about two. EDTA had a dramatic effect on the sorption of Co even at low concentrations, reducing the R d by up to two orders of magnitude. At EDTA concentrations greater than 5 mg/l, there was no further reduction in sorption. EDTA was not itself sorbed, but formed a mobile complex with Co. Differences in distribution ratios were observed depending on whether the cobalt was added before or after EDTA. Within the same period of equilibrium, the R d values were higher when cobalt was allowed to equilibrate with the sand before adding EDTA. The desorption of cobalt from the mineral surface may be a rate-limiting step such that equilibrium was not achieved within the 14-day period of these experiments. Acetate had no effect on cobalt sorption in any of the experiments undertaken. This work is part of the Commission Mirage project, Phase 2, research area Geochemistry of actinides and fission products in natural aquifer systems

Twinned low-temperature structures of tris(ethylenediamine)zinc(II) sulfate and tris(ethylenediamine)copper(II) sulfate

NARCIS (Netherlands)

Lutz, M.

2010-01-01

Tris(ethylenediamine)zinc(II) sulfate, [Zn(C2H8N2)3]SO4, (I), undergoes a reversible solid–solid phase transition during cooling, accompanied by a lowering of the symmetry from high-trigonal P31c to low-trigonal P3 and by merohedral twinning. The molecular symmetries of the cation and anion change

The effect of organics on the sorption of cobalt by glacial sand in laboratory experiments

International Nuclear Information System (INIS)

Haigh, G.; Williams, G.M.; Hooker, P.J.; Ross, C.A.M.; Allen, M.R.

1989-02-01

The effect of acetate, EDTA and natural organic compounds in groundwater at Drigg test site, on the sorption of cobalt by glacial sand has been studied in a series of batch experiments. Removing 50% of the organic material from the groundwater with DEAE cellulose increased the distribution ratio (R d ) of cobalt by a factor of about two. The addition of both EDTA and acetate to the sand/water system led to the removal of Ca, Mg, Sr and Ba from solution. Both organic compounds had the effect of reducing the pH and bicarbonated concentrations. EDTA also removed iron from the solution. EDTA reduced the R d for Co by up to 2 orders of magnitude. At EDTA concentrations greater than 5mg/1, there was no further reduction in sorption. EDTA was not itself sorbed, but formed a mobile complex with Co. Within the same period of equilibrium, the R d values were lower when EDTA was allowed to equilibrate with the sand before adding cobalt. The desorption of cobalt from the minerals surface may be a rate limiting step such that equilibrium was not achieved within the 14 day period of these experiments. Acetate had no effect of cobalt sorption. (author)

Topotactic Synthesis of Porous Cobalt Ferrite Platelets from a Layered Double Hydroxide Precursor and Their Application in Oxidation Catalysis.

Science.gov (United States)

Ortega, Klaus Friedel; Anke, Sven; Salamon, Soma; Özcan, Fatih; Heese, Justus; Andronescu, Corina; Landers, Joachim; Wende, Heiko; Schuhmann, Wolfgang; Muhler, Martin; Lunkenbein, Thomas; Behrens, Malte

2017-09-12

Monocrystalline, yet porous mosaic platelets of cobalt ferrite, CoFe 2 O 4 , can be synthesized from a layered double hydroxide (LDH) precursor by thermal decomposition. Using an equimolar mixture of Fe 2+ , Co 2+ , and Fe 3+ during co-precipitation, a mixture of LDH, (Fe II Co II ) 2/3 Fe III 1/3 (OH) 2 (CO 3 ) 1/6 ⋅m H 2 O, and the target spinel CoFe 2 O 4 can be obtained in the precursor. During calcination, the remaining Fe II fraction of the LDH is oxidized to Fe III leading to an overall Co 2+ :Fe 3+ ratio of 1:2 as required for spinel crystallization. This pre-adjustment of the spinel composition in the LDH precursor suggests a topotactic crystallization of cobalt ferrite and yields phase pure spinel in unusual anisotropic platelet morphology. The preferred topotactic relationship in most particles is [111] Spinel ∥[001] LDH . Due to the anion decomposition, holes are formed throughout the quasi monocrystalline platelets. This synthesis approach can be used for different ferrites and the unique microstructure leads to unusual chemical properties as shown by the application of the ex-LDH cobalt ferrite as catalyst in the selective oxidation of 2-propanol. Compared to commercial cobalt ferrite, which mainly catalyzes the oxidative dehydrogenation to acetone, the main reaction over the novel ex-LDH cobalt is dehydration to propene. Moreover, the oxygen evolution reaction (OER) activity of the ex-LDH catalyst was markedly higher compared to the commercial material. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical performance of cobalt hydroxide nanosheets formed by the delamination of layered cobalt hydroxide in water

Czech Academy of Sciences Publication Activity Database

Schneiderová, Barbora; Demel, Jan; Pleštil, Josef; Tarábková, Hana; Bohuslav, Jan; Lang, Kamil

2014-01-01

Roč. 43, č. 27 (2014), s. 10484-10491 ISSN 1477-9226 R&D Projects: GA ČR GP13-09462P Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:61389013 Keywords : Ray-absorption spectroscopy * Alpha-cobalt * Solvothermal decomposition * Nickel * Nanocomposites Subject RIV: CA - Inorganic Chemistry; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.197, year: 2014

Synthesis and photophysical properties of aluminium tris-(4-morpholine-8-hydroxyquinoline

Directory of Open Access Journals (Sweden)

Walaa A.E. Omar

2013-11-01

Full Text Available Aluminium tris(4-morpholinyl-8-hydroxyquinoline has been synthesized and characterized. The photoluminescence measurements showed that the new derivative is blue shifted and has relative photoluminescence quantum yield two times higher compared to the pristine Al tris(8-hydroxyquinoline. Deferential scanning colorimetric studies revealed that the newly synthesized Alq3 derivative in this work is amorphous material with the highest transition glass temperature value among the reported amorphous Alq3 derivatives.

ÜTRIS ja RIS / Ingmar Roos

Index Scriptorium Estoniae

Roos, Ingmar

2010-01-01

Maanteeamet on projekti „Ühistranspordi infosüsteemi arendamine“ (ÜTRIS) raames välja töötamas ühissõidukite reaalaja infosüsteemi (RIS). Nimetatud süsteemi abil tekib võimalus jälgida ühissõidukite sõiduplaani järgset teenindamist ning tuvastada kõrvalekalded plaanilisest sõidugraafikust

Crystal structure of tris[4-(dimethylaminopyridinium] tris(oxalato-κ2O,O′chromate(III tetrahydrate

Directory of Open Access Journals (Sweden)

Noé Makon ma Houga

2015-11-01

Full Text Available In the title hybrid salt, (C7H11N23[Cr(C2O43]·4H2O, the central CrIII ion of the complex anion (point group symmetry 2 is coordinated by six O atoms from three chelating oxalate(2− ligands in a slightly distorted octahedral coordination sphere. The Cr—O bond lengths vary from 1.9577 (11 to 1.9804 (11 Å, while the chelate O—Cr—O angles range from 82.11 (6 to 93.41 (5°. The 4-(dimethylaminopyridinium cations (one situated in a general position and one on a twofold rotation axis are protonated at the pyridine N atoms. In the crystal, N—H...O and O—H...O hydrogen bonds link the cations and anions into a three-dimensional network. π–π interactions between the pyridine rings of adjacent cations provide additional stabilization of the crystal packing, with the closest centroid-to-centroid distances being 3.541 (1 and 3.575 (1 Å.

Nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets with a 3D nanonetwork structure as supercapacitive materials

International Nuclear Information System (INIS)

Yan, Tao; Li, Ruiyi; Li, Zaijun

2014-01-01

Graphical abstract: The microwave heating reflux approach was developed for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets, in which ammonia and ethanol were used as the precipitator and medium for the synthesis. The obtained composite shows a 3D flowerclusters morphology with nanonetwork structure and largely enhanced supercapacitive performance. - Highlights: • The paper reported the microwave synthesis of nickel–cobalt layered double hydroxide/graphene composite. • The novel synthesis method is rapid, green, efficient and can be well used to the mass production. • The as-synthesized composite offers a 3D flowerclusters morphology with nanonetwork structure. • The composite offers excellent supercapacitive performance. • This study provides a promising route to design and synthesis of advanced graphene-based materials with the superiorities of time-saving and cost-effective characteristics. - Abstract: The study reported a novel microwave heating reflux method for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets (GS/NiCo-LDH). Ammonia and ethanol were employed as precipitant and reaction medium for the synthesis, respectively. The resulting GS/NiCo-LDH offers a 3D flowerclusters morphology with nanonetwork structure. Due to the greatly enhanced rate of electron transfer and mass transport, the GS/NiCo-LDH electrode exhibits excellent supercapacitive performances. The maximum specific capacitance was found to be 1980.7 F g −1 at the current density of 1 A g −1 . The specific capacitance can remain 1274.7 F g −1 at the current density of 15 A g −1 and it has an increase of about 2.9% after 1500 cycles. Moreover, the study also provides a promising approach for the design and synthesis of metallic double hydroxides/graphene hybrid materials with time-saving and cost-effective characteristics, which can be potentially applied

Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)

OpenAIRE

Jorgensen, J. D.; Avdeev, M.; Hinks, D. G.; Burley, J. C.; Short, S.

2003-01-01

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its anhydrous parent compound Na0.61(1)CoO2. The deuterate superconducting compound is formed by coordinating four D2O molecules (two above and two below) to each Na ion in a way that gives Na-O distances nearly equal to those in the parent compound. One deuteron of the D2...

Recent results on D meson decays from the MARK III

International Nuclear Information System (INIS)

Coward, D.H.

1985-10-01

The MARK III Collaboration recently completed the analysis of a number of decay modes of charged and neutral D mesons produced in electron-positron collisions near the peak of the psi(3770) resonance at SLAC's SPEAR storage ring. The mesons were produced nearly at rest in pairs, either D + D - or D 0 anti D 0 , at a center-of-mass energy below the threshold for DD production. The unique kinematics of the production allow us to isolate the charmed meson signal clearly and unambiguously. The data were collected with the MARK III Spectrometer, a large solid angle magnetic detector. Our data sample corresponds to an integrated luminosity of approximately 9.3 inverse picobarns. New results will be presented on the absolute branching ratios of D mesons into hadronic final states, branching ratios for three body decays via pseudoscalar-vector intermediate states, and branching ratios for Cabibbo allowed and Cabibbo suppressed decays. Inclusive and exclusive branching ratios for the semi-leptonic decays of D mesons will be presented, as well as the first measurement of the vector form factor in the decay D 0 → K - e + nu, evidence for interference in D + decays, and new information on the contributions of W exchange diagrams to D 0 decays

Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

International Nuclear Information System (INIS)

Chylewska, A.; Jacewicz, D.; Zarzeczanska, D.; Chmurzynski, L.

2008-01-01

The acid-base properties of analogous complex ions of chromium(III) and cobalt(III) in aqueous solution have been studied. The equilibrium constants for all metal complexes were determined by using potentiometric and spectrophotometric titration methods. First, dissociation constants for the studied complexes of Cr(III) and Co(III) were determined by means of the potentiometric titration method and using the STOICHIO computer programme. Then, pH-spectrophotometric titrations were performed and the OriginPro 7.5 computer programme was used to calculate the same constants. The measurements using both methods were carried out under the same conditions of temperature, T = 298.15 K, and over the same pH range 2.00-10.00, respectively. It turned out that the two methods used enabled us to obtain acidity constants in very good agreement

Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

Energy Technology Data Exchange (ETDEWEB)

Chylewska, A.; Jacewicz, D.; Zarzeczanska, D. [Department of Chemistry, University of Gdansk, Sobieskiego 18/19, 80-952 Gdansk (Poland); Chmurzynski, L. [Department of Chemistry, University of Gdansk, Sobieskiego 18/19, 80-952 Gdansk (Poland)], E-mail: lech@chem.univ.gda.pl

2008-08-15

The acid-base properties of analogous complex ions of chromium(III) and cobalt(III) in aqueous solution have been studied. The equilibrium constants for all metal complexes were determined by using potentiometric and spectrophotometric titration methods. First, dissociation constants for the studied complexes of Cr(III) and Co(III) were determined by means of the potentiometric titration method and using the STOICHIO computer programme. Then, pH-spectrophotometric titrations were performed and the OriginPro 7.5 computer programme was used to calculate the same constants. The measurements using both methods were carried out under the same conditions of temperature, T = 298.15 K, and over the same pH range 2.00-10.00, respectively. It turned out that the two methods used enabled us to obtain acidity constants in very good agreement.

Controlling the oxidation of bis-tridentate cobalt(ii) complexes having bis(2-pyridylalkyl)amines: ligand vs. metal oxidation.

Science.gov (United States)

Anjana, S; Donring, S; Sanjib, P; Varghese, B; Murthy, Narasimha N

2017-08-22

Two bis-tridentate chelated cobalt(ii) complexes, which differ in the ligand structure by a methylene group, activate molecular oxygen (O 2 ), and give different oxidation products. The O 2 reaction of [Co II (pepma) 2 ] 2+ (1) with unsymmetrical 2-(2-pyridyl)-N-(2-pyridylmethyl)ethanamine (pepma) results in ligand oxidation, to the corresponding Co(ii) imine complex [Co II (pepmi) 2 ] 2+ (2). Contrastingly, the Co(ii) complex [Co II (bpma) 2 ] 2+ (3) of similar symmetrical bis(2-pyridylmethyl)amine (bpma), undergoes metal oxidation, yielding a cobalt(iii) complex, [Co III (bpma) 2 ] 2+ (4). The reversibility of the amine to imine conversion and the stability of the Co(ii) imine complex (2) are investigated. Furthermore, the solution dynamics of Co(ii) complexes are highlighted with the help of paramagnetic 1 H-NMR spectroscopy.

Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins.

Science.gov (United States)

Rury, Aaron S; Wiley, Theodore E; Sension, Roseanne J

2015-03-17

tetraphenyl porphyrin chloride (Fe((III))TPPCl) exhibits picosecond decay to a metal centered d → d* (4)T state. This state decays on a ca. 16 ps time scale in room temperature solution but persists for much longer in a cryogenic glass. The photoreactivity of the (4)T state may lead to novel future applications for these compounds. In contrast, the nonplanar cob(III)alamins contain two axial ligands to the central cobalt atom. The upper axial ligand can be an alkyl group as in the two biologically active coenzymes or a nonalkyl ligand such as -CN in cyanocobalamin (vitamin B12) or -OH in hydroxocobalamin. The electronic structure, energy cascade, and bond cleavage of these compounds is sensitive to the details of the axial ligand. Nonalkylcobalamins exhibit ultrafast internal conversion to a low-lying state of metal to ligand or ligand to metal charge transfer character. The compounds are generally photostable with ground state recovery complete on a time scale of 2-7 ps in room temperature aqueous solution. Alkylcobalamins exhibit ultrafast internal conversion to an S1 state of d/π → π* character. Most compounds undergo bond cleavage from this state with near unit quantum yield within ∼100 ps. Recent theoretical calculations provide a potential energy surface accounting for these observations. Conformation dependent mixing of the corrin π and cobalt d orbitals plays a significant role in the observed photochemistry and photophysics.

A new family of NxOy pyridine-containing macrocycles: synthesis and characterization of their Y(III), Ln(III), Zn(II), and Cd(II) coordination compounds

International Nuclear Information System (INIS)

Lodeiro, C.; Bastida, R.; Bertolo, E.; Rodriguez, A.

2004-01-01

Reaction between 2,6-bis(2-formylphenoxymethyl)pyridine and N,N-bis(3-aminopropyl)methylamine or tris(2-aminoethyl)amine has been used as the starting point for the synthesis of seven oxa-aza macrocyclic ligands, five of them never reported previously. They all feature different pendant arms, which provide a wide range of coordination possibilities. The Schiff base macrocycles L 1 and L 4 and their reduced ligands L 2 and L 5 are derived from 2,6-bis(2-formylphenoxymethyl)pyridine and tris(2-aminoethyl)amine or N,N-bis(3-aminopropyl)methylamine, respectively. The reaction of L 1 with salicylaldehyde forms L 3 , which features an imine bond in the pendant arm. The ligand L 5 has been the precursor for the pendant-armed L 6 and L 7 , by alkylation of the free NH groups with methyl-imidazole or methyl-indole. By a template or a nontemplate approach, we have synthesized different mono- and dinuclear complexes with Y(III), Ln(III), Zn(II), and Cd(II) cations. Both the free macrocyclic ligands and their corresponding metal complexes have been characterized by microanalysis, IR, UV-vis, 1 H and 13 C NMR spectroscopy, FAB mass spectrometry, MS electrospray, and conductivity measurements. (author)

Green synthesis of cobalt (II, III) oxide nanoparticles using Moringa Oleifera natural extract as high electrochemical electrode for supercapacitors

Science.gov (United States)

Matinise, N.; Mayedwa, N.; Fuku, X. G.; Mongwaketsi, N.; Maaza, M.

2018-05-01

The research work involved the development of a better, inexpensive, reliable, easily and accurate way for the fabrication of Cobalt (II, III) oxide (Co3O4) nanoparticles through a green synthetic method using Moringa Oleifera extract. The electrochemical activity, crystalline structure, morphology, isothermal behaviour and optical properties of Co3O4 nanoparticles were studied using various characterization techniques. The X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) analysis confirmed the formation of Co3O4 nanoparticles. The pseudo-capacitor behaviour of spinel Co3O4 nanoparticles on Nickel foam electrode was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 3M KOH solution. The CV curve revealed a pairs of redox peaks, indicating the pseudo-capacitive characteristics of the Ni/Co3O4 electrode. EIS results showed a small semicircle and Warburg impedance, indicating that the electrochemical process on the surface electrode is kinetically and diffusion controlled. The charge-discharge results indicating that the specific capacitance Ni/Co3O4 electrode is approximately 1060 F/g at a discharge current density of at 2 A/g.

Synthesis and characterization of 1D tris(8-quinolinolato) aluminum fluorescent fibers by electrospinning

Energy Technology Data Exchange (ETDEWEB)

Yan Eryun [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Wang Cheng [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Laboratory of Polymer Chemistry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China); Huang Zonghao [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)], E-mail: huangzh295@nenu.edu.cn; Xin Yi; Tong Yanbin [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)

2007-08-25

A simple and versatile method called the electrospinning technology was used to fabricate poly(ethylene oxide) (PEO)/tris(8-quinolinolato) aluminum (Alq3) fluorescent hybrid fibers with smooth surface and uniform morphology. The morphology of fibers has been characterized by field emission scanning electron microscopy (FE-SEM) and fluorescence microscopy. The diameter of the hybrid fibers was narrowly between 800 and 850 nm. FTIR spectra analysis showed that the Alq3 molecules interacted with the oxygen atoms on the PEO chains, which resulted in the changes of the crystalline phase of Alq3 in the as-prepared fibers. The photoluminescence (PL) spectra analysis indicated that the hybrid fibers' peak position was red shifted due to the addition of PEO, compared with free standing Alq3.

Study on Modification of NaX Zeolites: The Cobalt (II-Exchange Kinetics and Surface Property Changes under Thermal Treatment

Directory of Open Access Journals (Sweden)

Hoai-Lam Tran

2016-01-01

Full Text Available The cobalt (II ion-exchange process followed the Freundlich and Langmuir adsorption models as well as the pseudo-second-order kinetic model. The cobalt-exchanged contents increased when the initial Co(NO32 solution concentration increased up to 0.14 mol L−1 at the optimal pH of 6.05. The N2 adsorption isotherms are mixed types I/II isotherms and H3 type hysteresis. Both the micropore and mesopore adsorptions occurred during the adsorption process. The modification, which is both the cobalt (II exchange and thermal treatment, significantly improved the surface properties of NaX zeolites. Accordingly, the optimal temperature range is 500 to 600°C for a thermal treatment. This is consistent with the results of XRD analysis.

Cobalt metabolism and toxicology—A brief update

International Nuclear Information System (INIS)

Simonsen, Lars Ole; Harbak, Henrik; Bennekou, Poul

2012-01-01

Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co 2+ ) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co 2+ ) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co 2+ ) have recently been proposed to be due to putative inhibition of Ca 2+ entry and Ca 2+ -signaling and competition with Ca 2+ for intracellular Ca 2+ -binding proteins. The tissue partitioning of cobalt (Co 2+ ) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow phase lasting several weeks, and

Harnessing redox activity for the formation of uranium tris(imido) compounds

Science.gov (United States)

Anderson, Nickolas H.; Odoh, Samuel O.; Yao, Yiyi; Williams, Ursula J.; Schaefer, Brian A.; Kiernicki, John J.; Lewis, Andrew J.; Goshert, Mitchell D.; Fanwick, Phillip E.; Schelter, Eric J.; Walensky, Justin R.; Gagliardi, Laura; Bart, Suzanne C.

2014-10-01

Classically, late transition-metal organometallic compounds promote multielectron processes solely through the change in oxidation state of the metal centre. In contrast, uranium typically undergoes single-electron chemistry. However, using redox-active ligands can engage multielectron reactivity at this metal in analogy to transition metals. Here we show that a redox-flexible pyridine(diimine) ligand can stabilize a series of highly reduced uranium coordination complexes by storing one, two or three electrons in the ligand. These species reduce organoazides easily to form uranium-nitrogen multiple bonds with the release of dinitrogen. The extent of ligand reduction dictates the formation of uranium mono-, bis- and tris(imido) products. Spectroscopic and structural characterization of these compounds supports the idea that electrons are stored in the ligand framework and used in subsequent reactivity. Computational analyses of the uranium imido products probed their molecular and electronic structures, which facilitated a comparison between the bonding in the tris(imido) structure and its tris(oxo) analogue.

Bis[tris(1H-pyrazol-1-yl-κN2methane]nickel(II bis{[tris(1H-pyrazol-1-yl-κN2methane]tris(thiocyanato-κNnickelate(II} methanol disolvate

Directory of Open Access Journals (Sweden)

Ganna Lyubartseva

2011-12-01

Full Text Available Attempts to prepare the mononuclear [(tpmNiIIL3]−1 [tpm = tris(1H-pyrazol-1-ylmethane and L = thiocyanate] anion yielded the methanol-solvated salt, [(tpm2NiII][(tpmNiII(NCS3]2·2CH3OH or [Ni(C10H10N62][Ni(NCS3(C10H10N6]2·2CH3OH. The asymmetric unit consists of half a centrosymmetric bis[tris(1H-pyrazol-1-ylmethane]nickel(II cation and an octahedral nickelate(II anion bound to one tpm and three L ligands, and a methanol solvent molecule. One of the L ligands is disordered over two positions with occupancy factors of 0.650 (3 and 0.350 (3. There are O—H...S interactions between the methanol and the disordered thiocyanate anion, and a weak C—H...O hydrogen bond between the cation and the methanol O atom.

NMR spectroscopic determination of an equilibrium isotope effect on the hydration of cobalt(II)

International Nuclear Information System (INIS)

Evilia, R.F.; Saunders, M.

1985-01-01

A recently reported NMR method for the measurement of deuterium equilibrium isotope effects is applied to the hydration of the paramagnetic cobalt(II) ion. An isotope effect of about 1.3% is measured. A substantial difference between the intrinsic shift of H 2 O and D 2 O when coordinated to cobalt is also measured

Redetermination of dicerium(III) tris­(sulfate) tetra­hydrate

Science.gov (United States)

Xu, Xin

2008-01-01

Ce2(SO4)3(H2O)4 was obtained hydro­thermally from an aqueous solution of cerium(III) oxide, trimethyl­amine and sulfuric acid. The precision of the structure determination has been significantly improved compared with the previous result [Dereigne (1972 ▶). Bull. Soc. Fr. Mineral. Cristallogr. 95, 269–280]. The coordination about the two Ce atoms is achieved by seven and six bridging O atoms from sulfate anions. Each S atom makes four S—O—Ce linkages through bridging O atoms. The coordination sphere of each Ce is completed by two water molecules, which act as terminal ligands. PMID:21200451

Cobalt metabolism and toxicology-A brief update

Energy Technology Data Exchange (ETDEWEB)

Simonsen, Lars Ole, E-mail: LOSimonsen@dadlnet.dk; Harbak, Henrik; Bennekou, Poul

2012-08-15

Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co{sup 2+}) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co{sup 2+}) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co{sup 2+}) have recently been proposed to be due to putative inhibition of Ca{sup 2+} entry and Ca{sup 2+}-signaling and competition with Ca{sup 2+} for intracellular Ca{sup 2+}-binding proteins. The tissue partitioning of cobalt (Co{sup 2+}) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow

The ARIES-III D-3He tokamak reactor

International Nuclear Information System (INIS)

Bathke, C.G.; Werley, K.A.; Miller, R.L.; Krakowski, R.A.; Santarius, J.F.

1992-01-01

The multi-institutional ARIES study has generated a conceptual design of another tokamak fusion reactor in a series that varies the assumed advances in technology and physics. The ARIES-III design uses a D- 3 He fuel cycle and requires advances in technology and physics for economical attractiveness. The optimal design was characterized through systems analyses for eventual conceptual engineering design. In this paper, results from the systems analysis are summarized, and a comparison with the high-field, D-T fueled ARIES-I is included

Synthesis and characterization of cobalt/gold bimetallic nanoparticles

International Nuclear Information System (INIS)

Cheng, Guangjun; Hight Walker, Angela R.

2007-01-01

Cobalt/gold (Co/Au) bimetallic nanoparticles are prepared by chemically reducing gold (III) chloride to gold in the presence of pre-synthesized Co nanoparticles. Transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectrometry, and a superconducting quantum interference device (SQUID) magnetometer have been used to characterize as-prepared bimetallic nanoparticles. Our findings demonstrate Au not only grows onto Co nanoparticles, forming a surface coating, but also diffuses into Co nanoparticles. The introduction of Au alters the crystalline structure of Co nanoparticles and changes their magnetic properties. Dodecanethiols induce a reorganization of as-prepared Co/Au bimetallic nanoparticles

Cobalt Fischer-Tropsch catalysts: influence of cobalt dispersion and titanium oxides promotion

Energy Technology Data Exchange (ETDEWEB)

Azib, H

1996-04-10

The aim of this work is to study the effect of Sol-Gel preparation parameters which occur in silica supported cobalt catalysts synthesis. These catalysts are particularly used for the waxes production in natural gas processing. The solids have been characterized by several techniques: transmission electron microscopy (TEM), X-ray absorption near edge spectroscopy (XANES), programmed temperature reduction (TPR), infrared spectroscopy (IR), ultraviolet spectroscopy (UV), Magnetism, thermodesorption of H{sub 2} (TPD). The results indicate that the control of the cobalt dispersion and oxide phases nature is possible by modifying Sol-Gel parameters. The catalytic tests in Fischer-Tropsch synthesis were conducted on a pilot unit under pressure (20 atm) and suggested that turnover rates were independent of Co crystallite size, Co phases in the solids (Co deg., cobalt silicate) and titanium oxide promotion. On the other methane, the C{sub 3}{sup +} hydrocarbon selectivity is increased with increasing crystallite size. Inversely, the methane production is favoured by very small crystallites, cobalt silicate increase and titanium addition. However, the latter, used as a cobalt promoter, has a benefic effect on the active phase stability during the synthesis. (author). 149 refs., 102 figs., 71 tabs.

Low coordinated mononuclear erbium(iii) single-molecule magnets with C3v symmetry: a method for altering single-molecule magnet properties by incorporating hard and soft donors.

Science.gov (United States)

Zhang, Haitao; Nakanishi, Ryo; Katoh, Keiichi; Breedlove, Brian K; Kitagawa, Yasutaka; Yamashita, Masahiro

2018-01-02

Structures and magnetic characteristics of two three-coordinate erbium(iii) compounds with C 3v geometry, tris(2,6-di-tert-butyl-p-cresolate)erbium, Er(dbpc) 3 (1) and tris(bis(trimethylsilyl)methyl)erbium, Er(btmsm) 3 (2), were determined. Both underwent temperature-dependent slow magnetic relaxation processes in the absence of an external magnetic field. As a result of the differences in the coordination environment, they exhibit different energy barriers and quantum tunneling of magnetization (QTM) constants.

Structural and chemical reactivity modifications of a cobalt perovskite induced by Sr-substitution. An in situ XAS study

International Nuclear Information System (INIS)

Hueso, Jose L.; Holgado, Juan P.; Pereñíguez, Rosa; Gonzalez-DelaCruz, V.M.; Caballero, Alfonso

2015-01-01

LaCoO 3 and La 0.5 Sr 0.5 CoO 3−δ perovskites have been studied by in situ Co K-edge XAS. Although the partial substitution of La(III) by Sr(II) species induces an important increase in the catalytic oxidation activity and modifies the electronic state of the perovskite, no changes could be detected in the oxidation state of cobalt atoms. So, maintaining the electroneutrality of the perovskite requires the generation of oxygen vacancies in the network. The presence of these vacancies explains that the substituted perovskite is now much more reducible than the original LaCoO 3 perovskite. As detected by in situ XAS, after a consecutive reduction and oxidation treatment, the original crystalline structure of the LaCoO 3 perovskite is maintained, although in a more disordered state, which is not the case for the Sr doped perovskite. So, the La 0.5 Sr 0.5 CoO 3−δ perovskite submitted to the same hydrogen reduction treatment produces metallic cobalt, while as determined by in situ XAS spectroscopy the subsequent oxidation treatment yields a Co(III) oxide phase with spinel structure. Surprisingly, no Co(II) species are detected in this new spinel phase. - Highlights: • A Sr-substituted lanthanum cobalt perovskite has been prepared by spray pyrolysis. • It has been established that Co(III) cations are present in both perovskites. • LaCoO 3 is a less reducible phase than the substituted La 0.5 Sr 0.5 CoO 3−δ . • After reoxidation of reduced La 0.5 Sr 0.5 CoO 3−δ , a 100% Co(III) spinel is obtained

Cobalt accumulation and circulation by blackgum trees

International Nuclear Information System (INIS)

Thomas, W.A.

1975-01-01

Blackgum (Nyssa sylvatica Marsh.) trees accumulate far greater concentrations of cobalt in mature foliage than do other species on the same site (363 ppM in ash of blackgum, compared with about 3 ppM by mockernut hickory and about 1 ppM by red maple, tulip tree, and white oak). Cobalt concentrations in dormant woody tissues of blackgum also significantly exceed those in the other four species. Inoculation of six blackgums with 60 Co revealed that cobalt remains mobile in the trees for at least 3 years. Foliar concentrations of stable cobalt increase uniformly until senescence. In late August, foliage accounts for only 9 percent of total tree weight but 57 percent of total tree cobalt. Losses of cobalt from trees occur almost entirely by leaf abscission, and the loss rates of weight and cobalt from decomposing litter are similar. Retention of cobalt in the biologically active soil layers perpetuates zones of cobalt concentration created by this species in woodlands

Cobalt-60 production in CANDU power reactors

International Nuclear Information System (INIS)

Slack, J.; Norton, J.L.; Malkoske, G.R.

2003-01-01

MDS Nordion has been supplying cobalt-60 sources to industry for industrial and medical purposes since 1946. These cobalt-60 sources are used in many market and product segments. The major application is in the health care industry where irradiators are used to sterilize single use medical products. These irradiators are designed and built by MDS Nordion and are used by manufacturers of surgical kits, gloves, gowns, drapes and other medical products. The irradiator is a large shielded room with a storage pool for the cobalt-60 sources. The medical products are circulated through the shielded room and exposed to the cobalt-60 sources. This treatment sterilizes the medical products which can then be shipped to hospitals for immediate use. Other applications for this irradiation technology include sanitisation of cosmetics, microbial reduction of pharmaceutical raw materials and food irradiation. The cobalt-60 sources are manufactured by MDS Nordion in their Cobalt Operations Facility in Kanata. More than 75,000 cobalt-60 sources for use in irradiators have been manufactured by MDS Nordion. The cobalt-60 sources are double encapsulated in stainless steel capsules, seal welded and helium leak tested. Each source may contain up to 14,000 curies. These sources are shipped to over 170 industrial irradiators around the world. This paper will focus on the MDS Nordion proprietary technology used to produce the cobalt-60 isotope in CANDU reactors. Almost 55 years ago MDS Nordion and Atomic Energy of Canada developed the process for manufacturing cobalt-60 at the Chalk River Labs, in Ontario, Canada. A cobalt-59 target was introduced into a research reactor where the cobalt-59 atom absorbed one neutron to become cobalt-60. Once the cobalt-60 material was removed from the research reactor it was encapsulated in stainless steel and seal welded using a Tungsten Inert Gas weld. The first cobalt-60 sources manufactured using material from the Chalk River Labs were used in cancer

The acceleration of dissolved cobalt's ecological stoichiometry due to biological uptake, remineralization, and scavenging in the Atlantic Ocean

Science.gov (United States)

Saito, Mak A.; Noble, Abigail E.; Hawco, Nicholas; Twining, Benjamin S.; Ohnemus, Daniel C.; John, Seth G.; Lam, Phoebe; Conway, Tim M.; Johnson, Rod; Moran, Dawn; McIlvin, Matthew

2017-10-01

The stoichiometry of biological components and their influence on dissolved distributions have long been of interest in the study of the oceans. Cobalt has the smallest oceanic inventory of inorganic micronutrients and hence is particularly vulnerable to influence by internal oceanic processes including euphotic zone uptake, remineralization, and scavenging. Here we observe not only large variations in dCo : P stoichiometry but also the acceleration of those dCo : P ratios in the upper water column in response to several environmental processes. The ecological stoichiometry of total dissolved cobalt (dCo) was examined using data from a US North Atlantic GEOTRACES transect and from a zonal South Atlantic GEOTRACES-compliant transect (GA03/3e and GAc01) by Redfieldian analysis of its statistical relationships with the macronutrient phosphate. Trends in the dissolved cobalt to phosphate (dCo : P) stoichiometric relationships were evident in the basin-scale vertical structure of cobalt, with positive dCo : P slopes in the euphotic zone and negative slopes found in the ocean interior and in coastal environments. The euphotic positive slopes were often found to accelerate towards the surface and this was interpreted as being due to the combined influence of depleted phosphate, phosphorus-sparing (conserving) mechanisms, increased alkaline phosphatase metalloenzyme production (a zinc or perhaps cobalt enzyme), and biochemical substitution of Co for depleted Zn. Consistent with this, dissolved Zn (dZn) was found to be drawn down to only 2-fold more than dCo, despite being more than 18-fold more abundant in the ocean interior. Particulate cobalt concentrations increased in abundance from the base of the euphotic zone to become ˜ 10 % of the overall cobalt inventory in the upper euphotic zone with high stoichiometric values of ˜ 400 µmol Co mol-1 P. Metaproteomic results from the Bermuda Atlantic Time-series Study (BATS) station found cyanobacterial isoforms of the

Electroplated zinc-cobalt alloy

International Nuclear Information System (INIS)

Carpenter, D.E.O.S.; Farr, J.P.G.

2005-01-01

Recent work on the deposition and use of ectrodeposited zinc-cobalt alloys is surveyed. Alloys containing lower of Nuclear quantities of cobalt are potentially more useful. The structures of the deposits is related to their chemical and mechanical properties. The inclusion of oxide and its role in the deposition mechanism may be significant. Chemical and engineering properties relate to the metallurgical structure of the alloys, which derives from the mechanism of deposition. The inclusion of oxides and hydroxides in the electroplate may provide evidence for this mechanism. Electrochemical impedance measurements have been made at significant deposition potentials, in alkaline electrolytes. These reveal a complex electrode behaviour which depends not only on the electrode potential but on the Co content of the electrolyte. For the relevant range of cathodic potential zinc-cobalt alloy electrodeposition occurs through a stratified interface. The formation of an absorbed layer ZnOH/sup +/ is the initial step, this inhibits the deposition of cobalt at low cathodic potentials, so explaining its 'anomalous deposition'. A porous layer of zinc forms on the adsorbed ZnOH/sup +/ at underpotential. As the potential becomes more cathodic, cobalt co- deposits from its electrolytic complex forming a metallic solid solution of Co in Zn. In electrolytes containing a high concentration of cobalt a mixed entity (ZnCo)/sub +/ is assumed to adsorb at the cathode from which a CoZn intermetallic deposits. (author)

Cobalt allergy in hard metal workers

Energy Technology Data Exchange (ETDEWEB)

Fischer, T; Rystedt, I

1983-03-01

Hard metal contains about 10% cobalt. 853 hard metal workers were examined and patch tested with substances from their environment. Initial patch tests with 1% cobalt chloride showed 62 positive reactions. By means of secondary serial dilution tests, allergic reactions to cobalt were reproduced in 9 men and 30 women. Weak reactions could not normally be reproduced. A history of hand eczema was found in 36 of the 39 individuals with reproducible positive test reactions to cobalt, while 21 of 23 with a positive initial patch test but negative serial dilution test had never had any skin problems. Hand etching and hand grinding, mainly female activities and traumatic to the hands, were found to involve the greatest risk of cobalt sensitization. 24 individuals had an isolated cobalt allergy. They had probably been sensitized by hard metal work, while the individuals, all women, who had simultaneous nickel allergy had probably been sensitized to nickel before their employment and then became sensitized to cobalt by hard metal work. A traumatic occupation, which causes irritant contact dermatitis and/or a previous contact allergy or atopy is probably a prerequisite for the development of cobalt allergy.

Forward-planned intensity modulated radiation therapy using a cobalt source: A dosimetric study in breast cancer

Directory of Open Access Journals (Sweden)

Savino Cilla

2013-01-01

Full Text Available This analysis evaluates the feasibility and dosimetric results of a simplified intensity-modulated radiotherapy (IMRT treatment using a cobalt-therapy unit for post-operative breast cancer. Fourteen patients were included. Three plans per patient were produced by a cobalt-60 source: A standard plan with two wedged tangential beams, a standard tangential plan optimized without the use of wedges and a plan based on the forward-planned "field-in-field" IMRT technique (Co-FinF where the dose on each of the two tangential beams was split into two different segments and the two segments weight was determined with an iterative process. For comparison purposes, a 6-MV photon standard wedged tangential treatment plan was generated. D mean , D 98% , D 2% , V 95% , V 107%, homogeneity, and conformity indices were chosen as parameters for comparison. Co-FinF technique improved the planning target volume dose homogeneity compared to other cobalt-based techniques and reduced maximum doses (D 2% and high-dose volume (V 110% . Moreover, it showed a better lung and heart dose sparing with respect to the standard approach. The higher dose homogeneity may encourage the adoption of accelerated-hypofractionated treatments also with the cobalt sources. This approach can promote the spread of breast conservative treatment in developing countries.

Pharmacokinetics of inorganic cobalt and a vitamin B12 supplement in the Thoroughbred horse: Differentiating cobalt abuse from supplementation.

Science.gov (United States)

Hillyer, L L; Ridd, Z; Fenwick, S; Hincks, P; Paine, S W

2018-05-01

While cobalt is an essential micronutrient for vitamin B 12 synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. To devise a scientific basis for differentiation between presence of cobalt from bona fide supplementation and cobalt doping through the use of ratios. Six Thoroughbred horses were given 10 mL vitamin B 12 /cobalt supplement (Hemo-15 ® ; Vetoquinol, Buckingham, Buckinghamshire, UK., 1.5 mg B 12 , 7 mg cobalt gluconate = 983 μg total Co) as an i.v. bolus then an i.v. infusion (15 min) of 100 mg cobalt chloride (45.39 mg Co) 6 weeks later. Pre-and post-administration plasma and urine samples were analysed for cobalt and vitamin B 12 . Urine and plasma samples were analysed for vitamin B 12 using an immunoassay and cobalt concentrations were measured via ICP-MS. Baseline concentrations of cobalt in urine and plasma for each horse were subtracted from their cobalt concentrations post-administration for the PK analysis. Compartmental analysis was used for the determination of plasma PK parameters for cobalt using commercially available software. On administration of a vitamin B 12 /cobalt supplement, the ratio of cobalt to vitamin B 12 in plasma rapidly increased to approximately 3 and then rapidly declined below a ratio of 1 and then back to near baseline over the next week. On administration of 100 mg cobalt chloride, the ratio initially exceeded 10 in plasma and then declined with the lower 95% confidence interval remaining above a ratio of 1 for 7 days. For two horses with extended sampling, the plasma ratio remained above one for

Complexes superstructurés mixtes Ru/Fe et Ru/Co à ligands polypyridinyles multitopiques : synthèses, caractérisations, propriétés rédox et photorédox.

OpenAIRE

Lombard , Jean

2007-01-01

This work deals with the synthesis and physico-chemical study of heterobimetallic complexes bearing ruthenium(II)-tris-bipyridine units as photosensitizers covalently linked to a polypyridinic complex unit of iron (II) or cobalt (II), in order to investigate photoinduced electron transfer in such architectures.With bis-bipyridine type ligands, we synthesized a serie of tetranuclear complexes formed by a central complex unit FeII-tris-bipyridine, covalently linked to three RuII-tris-bipyridine...

COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

Directory of Open Access Journals (Sweden)

Liudmila V. Dyakova

2010-06-01

Full Text Available The paper deals with the extracting cobalt salts by using mixtures on the basis of tertiary amine from multicomponent solutions from the process of hydrochloride leaching of cobalt concentrate. The optimal composition for the extraction mixture, the relationship between the cobalt distribution coefficients and modifier’s nature and concentration, and the saltingout agent type have been determined. A hydrochloride extraction technology of cobalt concentrate yielding a purified concentrated cobalt solution for the production of pure cobalt salts has been developed and introduced at Severonikel combine.

Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

International Nuclear Information System (INIS)

Qi, B.; Andrew, J. S.; Arnold, D. P.

2017-01-01

This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe_6_6Co_3_4) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe_2O_4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

Energy Technology Data Exchange (ETDEWEB)

Qi, B. [University of Florida, Interdisciplinary Microsystems Group, Department of Electrical and Computer Engineering (United States); Andrew, J. S. [University of Florida, Department of Materials Science and Engineering (United States); Arnold, D. P., E-mail: darnold@ufl.edu [University of Florida, Interdisciplinary Microsystems Group, Department of Electrical and Computer Engineering (United States)

2017-03-15

This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe{sub 66}Co{sub 34}) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

Environmental mobility of cobalt-Influence of solid phase characteristics and groundwater chemistry

International Nuclear Information System (INIS)

Payne, T.E.; Itakura, T.; Comarmond, M.J.; Harrison, J.J.

2009-01-01

The adsorption of cobalt on samples from a potential waste repository site in an arid region was investigated in batch experiments, as a function of various solution phase parameters including the pH and ionic strength. The samples were characterized using a range of techniques, including BET surface area measurements, total clay content and quantitative X-ray diffraction. The statistical relationships between the measured cobalt distribution coefficients (K d values) and the solid and liquid phase characteristics were assessed. The sorption of cobalt increased with the pH of the aqueous phase. In experiments with a fixed pH value, the measured K d values were strongly correlated to the BET surface area, but not to the amount of individual clay minerals (illite, kaolinite or smectite). A further set of sorption experiments was undertaken with two samples of distinctive mineralogy and surface area, and consequently different sorption properties. A simple surface complexation model (SCM) that conceptualized the surface sites as having equivalent sorption properties to amorphous Fe-oxide was moderately successful in explaining the pH dependence of the sorption data on these samples. Two different methods of quantifying the input parameters for the SCM were assessed. While a full SCM for cobalt sorption on these complex environmental substrates is not yet possible, the basic applicability and predictive capability of this type of modeling is demonstrated. A principal requirement to further develop the modeling approach is adequate models for cobalt sorption on component mineral phases of complex environmental sorbents.

Heterometallic modular metal-organic 3D frameworks assembled via new tris-β-diketonate metalloligands: nanoporous materials for anion exchange and scaffolding of selected anionic guests.

Science.gov (United States)

Carlucci, Lucia; Ciani, Gianfranco; Maggini, Simona; Proserpio, Davide M; Visconti, Marco

2010-11-02

The modular engineering of heterometallic nanoporous metal-organic frameworks (MOFs) based on novel tris-chelate metalloligands, prepared using the functionalised β-diketone 1,3-bis(4'-cyanophenyl)-1,3-propanedione (HL), is described. The complexes [M(III)L(3)] (M=Fe(3+), Co(3+)) and [M(II)L(3)](NEt(4)) (M=Mn(2+), Co(2+), Zn(2+), Cd(2+)) have been synthesised and characterised, all of which exhibit a distorted octahedral chiral structure. The presence of six exo-oriented cyano donor groups on each complex makes it a suitable building block for networking through interactions with external metal ions. We have prepared two families of MOFs by reacting the metalloligands [M(III)L(3)] and [M(II)L(3)](-) with many silver salts AgX (X=NO(3)(-), BF(4)(-), PF(6)(-), AsF(6)(-), SbF(6)(-), CF(3)SO(3)(-), tosylate), specifically the [M(III)L(3)Ag(3)]X(3)·Solv and [M(II)L(3)Ag(3)]X(2)·Solv network species. Very interestingly, all of these network species exhibit the same type of 3D structure and crystallise in the same trigonal space group with similar cell parameters, in spite of the different metal ions, ionic charges and X(-) counteranions of the silver salts. We have also succeeded in synthesising trimetallic species such as [Zn(x)Fe(y)L(3)Ag(3)](ClO(4))((2x+3y))·Solv and [Zn(x)Cd(y)L(3)Ag(3)](ClO(4))(2)·Solv (with x+y=1). All of the frameworks can be described as sixfold interpenetrated pcu nets, considering the Ag(+) ions as simple digonal spacers. Each individual net is homochiral, containing only Δ or Λ nodes; the whole array contains three nets of type Δ and three nets of type Λ. Otherwise, taking into account the presence of weak Ag-C σ bonds involving the central carbon atoms of the β-diketonate ligands of adjacent nets, the six interpenetrating pcu networks are joined into a unique non-interpenetrated six-connected frame with the rare acs topology. The networks contain large parallel channels of approximate hexagonal-shaped sections that represent 37

Tris-base buffer: a promising new inhibitor for cancer progression and metastasis.

Science.gov (United States)

Ibrahim-Hashim, Arig; Abrahams, Dominique; Enriquez-Navas, Pedro M; Luddy, Kim; Gatenby, Robert A; Gillies, Robert J

2017-07-01

Neutralizing tumor external acidity with oral buffers has proven effective for the prevention and inhibition of metastasis in several cancer mouse models. Solid tumors are highly acidic as a result of high glycolysis combined with an inadequate blood supply. Our prior work has shown that sodium bicarbonate, imidazole, and free-base (but not protonated) lysine are effective in reducing tumor progression and metastasis. However, a concern in translating these results to clinic has been the presence of counter ions and their potential undesirable side effects (e.g., hypernatremia). In this work, we investigate tris(hydroxymethyl)aminomethane, (THAM or Tris), a primary amine with no counter ion, for its effects on metastasis and progression in prostate and pancreatic cancer in vivo models using MRI and bioluminescence imaging. At an ad lib concentration of 200 mmol/L, Tris effectively inhibited metastasis in both models and furthermore led to a decrease in the expression of the major glucose transporter, GLUT-1. Our results also showed that Tris-base buffer (pH 8.4) had no overt toxicity to C3H mice even at higher doses (400 mmol/L). In conclusion, we have developed a novel therapeutic approach to manipulate tumor extracellular pH (pHe) that could be readily adapted to a clinical trial. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles

Directory of Open Access Journals (Sweden)

Gupta Hari Om

2009-01-01

Full Text Available Abstract Zn0.9Cd0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M particle size, d XRDis ~3.5 nm, while for high cobalt concentration (>0.05 M particle size decreases abruptly (~2 nm as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.

Synthesis and investigation of rare earth tris-acetylacetonates addUcts with acetylaceoneimine

International Nuclear Information System (INIS)

Trembovetskij, G.V.; Smirnov, E.V.; Murav'eva, I.A.; Martynenko, L.I.

1983-01-01

Adducts of tris-acetylacetonates of pare earths With acetylacetonimine of the composition MA 3 x2L (M=La, Pr, Nd, Eu, Gd, Tb) and MA 3 XL (M=Dy, Ho, Er, Tm, Yb, LU) have been synthesized. The compounds prepared are studied using the methods of elemental analysis, IR spectroscopy, PMR spectroscopy, X-ray phase analysis. Volatile tris-acetylacetonates of the yttrium subgroUp rare earths have been prepared by thermal decomposition of MA 3 xL in vacuum

Biosorption of copper(II), lead(II), iron(III) and cobalt(II) on Bacillus sphaericus-loaded Diaion SP-850 resin

International Nuclear Information System (INIS)

Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Usta, Canan; Soylak, Mustafa

2007-01-01

The biosorption of copper(II), lead(II), iron(III) and cobalt(II) on Bacillus sphaericus-loaded Diaion SP-850 resin for preconcentration-separation of them have been investigated. The sorbed analytes on biosorbent were eluted by using 1 mol L -1 HCl and analytes were determined by flame atomic absorption spectrometry. The influences of analytical parameters including amounts of pH, B. sphaericus, sample volume etc. on the quantitative recoveries of analytes were investigated. The effects of alkaline, earth alkaline ions and some metal ions on the retentions of the analytes on the biosorbent were also examined. Separation and preconcentration of Cu, Pb, Fe and Co ions from real samples was achieved quantitatively. The detection limits by 3 sigma for analyte ions were in the range of 0.20-0.75 μg L -1 for aqueous samples and in the range of 2.5-9.4 ng g -1 for solid samples. The validation of the procedure was performed by the analysis of the certified standard reference materials (NRCC-SLRS 4 Riverine Water, SRM 2711 Montana soil and GBW 07605 Tea). The presented method was applied to the determination of analyte ions in green tea, black tea, cultivated mushroom, boiled wheat, rice and soil samples with successfully results

Syntheses, crystal structures and fluorescent properties of three metal- tris(4‧-carboxybiphenyl)amine frameworks

Science.gov (United States)

Yuan, Lv-Bing; He, Yan-Ping; Xu, Hai; Zhang, Jian

2017-11-01

Triphenylamine and its derivatives have been widely concerned because of their excellent performance in the area of the photoelectric functional material. In this work, we chose a nanosized tris(4‧-carboxybiphenyl)amine (H3TPA) as organic ligand. By employing the H3TPA ligand to assemble with M2+ (M = Zn, Cd, and Pb) ions, respectively, three metal-organic frameworks (FIR-43 to FIR-45, FIR denotes Fujian Institute of Research) have been synthesized under different solvent systems. FIR-43 exhibits a 3-connected two-dimensional (2D) network based on mononuclear [Zn(COO)3] second building unit (SBU). Unlike the anionic framework FIR-43, FIR-44 is a neutral 2D layer constructed by trinuclear [Cd3(COO)6] SBU and displays a (3,6)-NbSe2 topology structure. If the weak Pb-O interactions in the range of 2.79-2.88 Å are considered, FIR-45 is a neutral 3D framework built by hexanuclear [Pb6(DMAE)6(COO)6] SBU (DMAE = N,N-dimethylethanolamine) and represents a (3,6)-connected (4·82)2(42·811·102) topology. Thermogravimetric analyses (TGA) and X-ray powder diffraction (PXRD) patterns were used to evaluate their thermal stability and phase purity. Photoluminescence studies showed that they exhibited strong emitting bands in the visible region with high quantum yields and long luminescent lifetimes. The assembly between nanosized tris((4-carboxyl)phenylduryl)amine ligand and M2+ (M = Zn, Cd, and Pb) ions leads to three new metal-organic frameworks, which show excellent fluorescent properties.

Growth morphology of zinc tris(thiourea) sulphate crystals

Indian Academy of Sciences (India)

The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman–Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A computer code is developed for carrying out ...

Silica from triethylammonium tris (oxalato) silicate (IV) thermal decomposition

International Nuclear Information System (INIS)

Ferracin, L.C.; Ionashiro, M.; Davolos, M.R.

1990-01-01

Silica can be obtained from differents precursors by differents methods. In this paper it has been investigated the thermal decomposition of triethylammonium tris (oxalato) silicate (IV) to render silica. Among the trisoxalato-complexes of silicon preparation methods reviewed it has been used the Bessler's one with the reflux adaptaded in microwave oven. Thermal decomposition analysis of the compound has been made by TG-DTG and DTA curves. Silica powders obtained and heated between 300 to 900 0 C in a oven were characterized by infrared vibrational spectroscopy, X-ray powder difraction and nitrogen adsorption isotherm (BET). The triethylammonium tris (oxalato) silicate (IV) thermal decomposition takes place at 300 0 C and the silica powder obtained is non cristalline with impurities that are eliminated with heating at 400 0 C. (author) [pt

Molecular dynamics simulation of thermophysical properties of undercooled liquid cobalt

International Nuclear Information System (INIS)

Han, X J; Wang, J Z; Chen, M; Guo, Z Y

2004-01-01

Molecular dynamics simulations with two different embedded-atom-method (EAM) potentials are applied to calculate the density, specific heat and self-diffusion coefficient of liquid cobalt at temperatures above and below the melting temperature. Simulation shows that Pasianot's EAM model of cobalt constructed on the basis of a hcp structure is more successful than Stoop's EAM model in the framework of a fcc structure in predicting the thermophysical properties of liquid cobalt. Simulations with Pasianot's EAM model indicate that the density fits into ρ = 7.49-9.17 x 10 -4 (T- T m ) g cm -3 , and the self-diffusion coefficient is given by D = 1.291 x 10 -7 exp(-48 795.71/RT) m 2 s -1 . Dissimilar to the linear dependence of the density and the Arrhenius dependence of the self-diffusion coefficient on temperature, the specific heat shows almost a constant value of 38.595 ± 0.084 J mol -1 K -1 within the temperature range of simulation. The simulated properties of liquid cobalt are compared with experimental data available. Comparisons show reasonable agreements between the simulated results from Pasianot's EAM model and experimental data

Cobalt-60 production in CANDU reactors

International Nuclear Information System (INIS)

Ross, Michel; Lemire, Christian

2002-01-01

CANDU reactors can produce cobalt-60 very efficiently and with an interesting return on investment. This paper discusses what is needed to convert a CANDU reactor into a cobalt-60 producer: what are the different phases, the safety studies required, the physical modifications needed, and what is the minimum involvement of the utility owning the plant. The past ten years of experience of Hydro-Quebec as a cobalt-60 producer will be reviewed, including the management of the risk of both incident and electricity generation loss, and including the benefits for the utility and its personnel. Originally a simple metal used for centuries as a pigment, cobalt-59 today is transformed into cobalt-60, a radioactive element of unprecedented value. Well known in medicine for cancer treatment, cobalt-60 is also used to sterilize a wide range of disposable medical products used in hospitals and to sanitize pharmaceutical and cosmetic products. Cobalt-60 is proving to be a new and effective solution, in the food sector, for preserving harvests and controlling food-borne diseases, or to advantageously replace certain gases and chemical products which are suspected of being harmful or carcinogenic. There are also other applications, such as: hardening of some plastics, treatment of sewage sludge and elimination of harmful insect populations. With a half-life of 5,3 years, cobalt-60 is a metal not found in nature. It is a radioactive isotope produced by exposing stable nuclei of cobalt-59 to neutrons. One of the best places to find such an important neutron source is a nuclear reactor. High energy gamma rays are then emitted during the process of radioactive decay, where cobalt-60 seeks again its stable state

Photoionization of cobalt impuritiesin zinc oxide

Czech Academy of Sciences Publication Activity Database

Ivanov, V.; Godlewski, M.; Dejneka, Alexandr

2015-01-01

Roč. 252, č. 9 (2015), s. 1988-1992 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) LM2011029; GA ČR GAP108/12/1941 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : absorption band * cobalt * photoionization * electron spin resonance * pulsed mode * ZnO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.522, year: 2015

Contrasting magnetism in dilute and supersaturated cobalt-fullerene mixture films

Czech Academy of Sciences Publication Activity Database

Lavrentiev, Vasyl; Stupakov, Alexandr; Pokorný, Jan; Lavrentieva, Inna; Vacík, Jiří; Dejneka, Alexandr; Barchuk, M.; Čapková, P.

2015-01-01

Roč. 48, č. 33 (2015), s. 335002 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : cobalt * fullerene * nanomagnetism * nanostructure * self-organization Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders; BM - Solid Matter Physics ; Magnetism (FZU-D) Impact factor: 2.772, year: 2015

PENGARUH PENGHILANGAN RAFINOSA DALAM PENGENCER TRIS AMINOMETHANE KUNING TELUR TERHADAP KUALITAS SEMEN KAMBING BOER SELAMA SIMPAN DINGIN

Directory of Open Access Journals (Sweden)

Abdul Rochim

2017-06-01

Full Text Available The objective of this research was to examine the effect of removal raffinose in tris aminomethane egg yolk diluents to semen quality of Boer goat during chilled preservation. This research was carried out at Animal Reproduction Laboratory and Sumber Sekar Laboratory, Animal Husbandry Faculty, Brawijaya University from December 11th 2016 to  January 31th 2017. Semen diluent was divided into two groups, there were P0 (80% Tris Aminomethane + 20% Egg Yolk; and P1 (80% Tris Aminomethane (without raffinose + 20% Egg Yolk. Parameter of this research was motility percentage, viability percentage, and abnormality percentage. Data of this research was analyzed using paired design t test. The result showed that after five days chilled preservation, was different (P0,05 in P1 treatment compared to the expectation value of 40 million sperm/ml. The conclution of this research was the tris aminomethane egg yolk diluent without raffinose could protect of Boer goat semen quality during chilled preservation.   Keywords: boer goat semen, tris aminomethane, raffinose, chilled preservation

Unusual stoichiometry control in the atomic layer deposition of manganese borate films from manganese bis(tris(pyrazolyl)borate) and ozone

International Nuclear Information System (INIS)

Klesko, Joseph P.; Bellow, James A.; Saly, Mark J.; Winter, Charles H.; Julin, Jaakko; Sajavaara, Timo

2016-01-01

The atomic layer deposition (ALD) of films with the approximate compositions Mn 3 (BO 3 ) 2 and CoB 2 O 4 is described using MnTp 2 or CoTp 2 [Tp = tris(pyrazolyl)borate] with ozone. The solid state decomposition temperatures of MnTp 2 and CoTp 2 are ∼370 and ∼340 °C, respectively. Preparative-scale sublimations of MnTp 2 and CoTp 2 at 210 °C/0.05 Torr afforded >99% recoveries with <0.1% nonvolatile residues. Self-limited ALD growth was demonstrated at 325 °C for MnTp 2 or CoTp 2 with ozone as the coreactant. The growth rate for the manganese borate process was 0.19 Å/cycle within the ALD window of 300–350 °C. The growth rate for the cobalt borate process was 0.39–0.42 Å/cycle at 325 °C. X-ray diffraction of the as-deposited films indicated that they were amorphous. Atomic force microscopy of 35–36 nm thick manganese borate films grown within the 300–350 °C ALD window showed root mean square surface roughnesses of 0.4–0.6 nm. Film stoichiometries were assessed by x-ray photoelectron spectroscopy and time of flight-elastic recoil detection analysis. The differing film stoichiometries obtained from the very similar precursors MnTp 2 and CoTp 2 are proposed to arise from the oxidizing ability of the intermediate high valent manganese oxide layers and lack thereof for cobalt.

Efficient luminescent materials based on the incorporation of a Eu(III)tris-(bipyridine-carboxylate) complex in mesoporous hybrid silicate hosts

International Nuclear Information System (INIS)

Botelho, M.B.S.; Queiroz, T.B. de; Eckert, H.; Camargo, A.S.S. de

2016-01-01

The study of the photoluminescent characteristics of host–guest systems based on highly emissive trivalent rare earth complexes such as Eu 3+ – tris-bipyridine-carboxylate, immobilized in solid state host matrices, is motivated by their potential applications in optoelectronic devices and bioanalytical systems. Besides offering the possibility of designing a favorable environment to improve the photophysical properties of the guest molecules, encapsulation in porous solids also serves to protect such molecules, prevents leakage (especially critical for bio-applications) and ultimately leads to more robust and versatile materials. Among the most interesting possible host matrices are mesoporous silica and hybrids (organo-silicates) in the form of powders (MCM-41 like) and transparent bulk or film xerogels. In this work we report the synthesis of highly efficient red emitting materials based on the wet impregnation of such host matrices with the new complex Eu[4-(4′-tert-butyl-biphenyl-4-yl)-2,2′-bipyridine-6-carboxyl] 3 (“[ t Bu–COO] 3 Eu”) whose synthesis and photophysical characterization was recently reported. Prior to the incorporation, the host matrices were thoroughly characterized by solid state 29 Si and 1 H NMR, N 2 adsorption/desorption isotherms, and scanning electron microscopy (SEM). Incorporation and retention of the complex molecules are found to be significantly higher in the phenyl-modified hybrid samples than in the regular mesoporous silica, suggesting efficient immobilization of the complex by π–π interactions. Long excited state lifetimes (up to 1.7 ms comparable to 1.8 ms for the complex in solution), and high quantum yields (up to 65%, versus 85% for the complex in solution) were measured for the bulk xerogel materials, suggesting the potential use of thin films for lighting and bioanalytical applications. - Highlights: • New Eu(III) complex in mesoporous hybrid matrices leads to highly emissive material • Matrix

Efficient luminescent materials based on the incorporation of a Eu(III)tris-(bipyridine-carboxylate) complex in mesoporous hybrid silicate hosts

Energy Technology Data Exchange (ETDEWEB)

Botelho, M.B.S. [Instituto de Física de São Carlos, Universidade de São Paulo, 13566-590 São Carlos, SP (Brazil); Universidade de Brasilia, 70910-900 Brasilia, DF (Brazil); Queiroz, T.B. de [Instituto de Física de São Carlos, Universidade de São Paulo, 13566-590 São Carlos, SP (Brazil); Eckert, H. [Instituto de Física de São Carlos, Universidade de São Paulo, 13566-590 São Carlos, SP (Brazil); Institut für Physikalische Chemie, Westfälische Wilhelms Universität Münster, D-48149 Münster (Germany); Camargo, A.S.S. de, E-mail: andreasc@ifsc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, 13566-590 São Carlos, SP (Brazil)

2016-02-15

The study of the photoluminescent characteristics of host–guest systems based on highly emissive trivalent rare earth complexes such as Eu{sup 3+} – tris-bipyridine-carboxylate, immobilized in solid state host matrices, is motivated by their potential applications in optoelectronic devices and bioanalytical systems. Besides offering the possibility of designing a favorable environment to improve the photophysical properties of the guest molecules, encapsulation in porous solids also serves to protect such molecules, prevents leakage (especially critical for bio-applications) and ultimately leads to more robust and versatile materials. Among the most interesting possible host matrices are mesoporous silica and hybrids (organo-silicates) in the form of powders (MCM-41 like) and transparent bulk or film xerogels. In this work we report the synthesis of highly efficient red emitting materials based on the wet impregnation of such host matrices with the new complex Eu[4-(4′-tert-butyl-biphenyl-4-yl)-2,2′-bipyridine-6-carboxyl]{sub 3} (“[{sup t}Bu–COO]{sub 3}Eu”) whose synthesis and photophysical characterization was recently reported. Prior to the incorporation, the host matrices were thoroughly characterized by solid state {sup 29}Si and {sup 1}H NMR, N{sub 2} adsorption/desorption isotherms, and scanning electron microscopy (SEM). Incorporation and retention of the complex molecules are found to be significantly higher in the phenyl-modified hybrid samples than in the regular mesoporous silica, suggesting efficient immobilization of the complex by π–π interactions. Long excited state lifetimes (up to 1.7 ms comparable to 1.8 ms for the complex in solution), and high quantum yields (up to 65%, versus 85% for the complex in solution) were measured for the bulk xerogel materials, suggesting the potential use of thin films for lighting and bioanalytical applications. - Highlights: • New Eu(III) complex in mesoporous hybrid matrices leads to highly

Surface tension and 0.1 MPa densities of imidazolium-, pyridinium-, pyrrolidinium-, and piperidinium-based tris(pentafluoroethyl)trifluorophosphate ionic liquids

Czech Academy of Sciences Publication Activity Database

Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav

2012-01-01

Roč. 333, NOV 15 2012 (2012), s. 38-46 ISSN 0378-3812 R&D Projects: GA ČR GA101/09/0010 Institutional research plan: CEZ:AV0Z20760514 Keywords : ionic liquid * tris(pentafluoroethyl)trifluorophosphate * density * surface tension Subject RIV: BJ - Thermodynamics Impact factor: 2.379, year: 2012 http://www.sciencedirect.com/science/article/pii/S037838121200310X

Studies of the yields of 57Fe(II)-species produced after the EC-decay and of 60Co(II)-species produced in the (n, γ) reaction in cobalt(III) coordination compounds

International Nuclear Information System (INIS)

Sano, Hirotoshi; Harada, Masayuki; Endo, Kazutoyo

1978-01-01

The yields of 57 Fe(II)-species produced after EC-decay were compared with those of 60 Co(II)-species produced in the 59 Co(n, γ) 60 Co reaction for twelve cobalt(III) coordination compounds. The results indicate that the radiochemical yield of 60 Co(II)-species correlates with the yield of 57 Fe(II)-species except in the case of [Co(NH 3 ) 6 ] 2 (CrO 4 ) 3 . The anomalously low yield of 57 Fe(II)-species in [Co(NH 3 ) 6 ] 2 (CrO 4 ) 3 is ascribed to the reaction of chromate anions with ammine ligands initiated by the nuclear transformation in a solid. (author)

Push-pull effect on the geometrical, optical and charge transfer properties of disubstituted derivatives of mer-tris(4-hydroxy-1,5-naphthyridinato aluminum (mer-AlND3

Directory of Open Access Journals (Sweden)

Rao Joshi Laxmikanth

2016-01-01

Full Text Available To design innovative and novel optical materials with high mobility, two kinds of disubstituted derivatives for mer-tris(4-hydroxy-1,5-naphthyridinato aluminum (mer-AlND3 with push (EDG–pull (EWG substituents have been designed. The structures of mer-tris(8-EDG-2-EWG-4-hydroxy-1,5-naphthyridinato aluminum (type I and mer-tris(8-EWG-2-EDG-4-hydroxy-1,5-naphthyridinato aluminum (type II in the ground and first excited states have been optimized at the B3LYP/6-31G(D and CIS/6-31G(D level of theory, respectively. It can be seen from frontier molecular orbitals analysis, in all these complexes, the highest occupied molecular orbital (HOMO is localized on the pyridine-4-ol ring of A-ligand while lowest unoccupied molecular orbital (LUMO is on the pyridyl ring of B-ligand in ground state irrespective of electron donor/acceptor substitution present on the ligands similar to that of mer-tris(8-hydroxyquinoline aluminum (mer-Alq3 and parent mer-AlND3.The absorption and emission wavelengths have been evaluated at the TD-PBE0/6-31G(D level and it can be see that all the type I derivatives show blue shift while most of the type II derivatives show red shift compared to mer-AlND3. All the disubstituted complexes have showed hypsochromic shifts in both the absorption and emission spectra when compared with the calculated absorption and emission spectra respectively of mer-Alq3. It can be seen that the reorganization energies of some of the disubstituted derivatives are comparable with mer-Alq3 and these derivatives might be good candidates for emitting materials in OLED.

Reaction pathway towards formation of cobalt single chain magnets and nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Balaji, G.; Desilva, Rohini M.; Palshin, V. [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Desilva, N. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Palmer, G. [Department of Biochemistry and Cell Biology, Rice University, MS 140, 6100 Main street, Houston, TX 77251 (United States); Kumar, Challa S.S.R., E-mail: ckumar1@lsu.ed [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States)

2010-03-15

With the advent of molecular magnets the quest for suitable high density magnetic storage materials has fuelled further research in this area. Here in this report, we present a detailed mechanistic investigation of thermal decomposition of cyclopentadienyl cobalt [CoCp(CO){sub 2}] precursor where Cp is the cyclopentadienyl moiety. The reaction revealed the formation of cobalt nanoparticles (Co-NPs) through an isolable reaction intermediate characterized as a Single Chain Magnet (SCM), [Co(Cp){sub 2}]{sub 2}CoCl{sub 4} (1). The SQUID magnetic measurements showed the presence of very strong antiferromagnetic interactions between Co{sup 2+} ions. The zero-field cooled (ZFC) and field cooled (FC) magnetization curves branch out below 5 K and there is evidence for frequency dependent complex susceptibility along with a maximum observed around 2.5 K. The optical studies indicated that the Co{sup 2+} d-d transition is influenced by the polarity of the solvents. The cobalt nanoparticles (Co-NPs) were obtained, either directly from 1 or from its precursor. They are spherical in shape with a mean size 15 nm, have fcc crystal structure and were found to be ferromagnetic at room temperature.

Electrocatalytic performance evaluation of cobalt hydroxide and cobalt oxide thin films for oxygen evolution reaction

Science.gov (United States)

Babar, P. T.; Lokhande, A. C.; Pawar, B. S.; Gang, M. G.; Jo, Eunjin; Go, Changsik; Suryawanshi, M. P.; Pawar, S. M.; Kim, Jin Hyeok

2018-01-01

The development of an inexpensive, stable, and highly active electrocatalyst for oxygen evolution reaction (OER) is essential for the practical application of water splitting. Herein, we have synthesized an electrodeposited cobalt hydroxide on nickel foam and subsequently annealed in an air atmosphere at 400 °C for 2 h. In-depth characterization of all the films using X-ray diffraction (XRD), X-ray photoelectron emission spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) techniques, which reveals major changes for their structural, morphological, compositional and electrochemical properties, respectively. The cobalt hydroxide nanosheet film shows high catalytic activity with 290 mV overpotential at 10 mA cm-2 and 91 mV dec-1 Tafel slope and robust stability (24 h) for OER in 1 M KOH electrolyte compared to cobalt oxide (340 mV). The better OER activity of cobalt hydroxide in comparison to cobalt oxide originated from high active sites, enhanced surface, and charge transport capability.

Cobalt sensitization and dermatitis

DEFF Research Database (Denmark)

Thyssen, Jacob P

2012-01-01

: This clinical review article presents clinical and scientific data on cobalt sensitization and dermatitis. It is concluded that cobalt despite being a strong sensitizer and a prevalent contact allergen to come up on patch testing should be regarded as a very complex metal to test with. Exposure...

Cobalt 60 availability for radiation processing

International Nuclear Information System (INIS)

Fraser, F.M.

1986-01-01

In the last 20 years, the steady and significant growth in the application of radiation processing to industrial sterilization has been seen. The principal application of this technology is the sterilization of disposable medical products, food irradiation, the irradiation of personal care goods and so on. At present, more than 70 million curies of cobalt-60 supplied by Atomic Energy of Canada Ltd. have been used for gamma processing in these applications. This is estimated to be more than 80 % of the total cobalt-60 in service in the world. Commercial food irradiation has an exciting future, and as to the impact of food irradiation on the availability of cobalt-60 over the next ten years, two principal factors must be examined, namely, the anticipated demand for cobalt-60 in all radiation processing applications, and the supply of cobalt-60 to reliably meet the expected demand. As for the cobalt-60 in service today, 90 % is used for the sterilization of disposable medical products, 5 % for food irradiation, and 5 % for other application. The demand for up to 30 million curies of cobalt-60 is expected over the next 10 years. Today, it is estimated that over 150,000 tons of spices, fruit and fish are irradiated. The potential cobalt-60 production could exceed 110 million curies per year. Gamma processing application will demand nearly 50 million curies in 1990. (Kako, I.)

Electroluminescence and Photoluminescence from a Fluorescent Cobalt Porphyrin Grafted on Graphene Oxide

Science.gov (United States)

Janghouri, Mohammad

2017-10-01

A new graphene oxide-cobalt porphyrin (GO-CoTPP) hybrid material has been used as an emissive layer in organic light-emitting diodes (OLEDs). Devices with fundamental structure of indium-doped tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, 45 nm)/polyvinylcarbazole (PVK):2-(4-biphenyl)-5-(4- t-butylphenyl)-1,3,4-oxadiazole (PBD):GO-CoTPP (70 nm)/1,3,5-tris( N-phenylbenzimidazol-2-yl)-benzene (TPBI, 20 nm)/Al (150 nm) were fabricated. A red electroluminescence (EL) was obtained from thin-film PVK:PBD:CoTPP at 70 nm thickness. When CoTPP was covalently grafted on graphene oxide (GO) sheets, near-white EL was obtained. The white emission, which was composed of bluish green and red, is attributed to electroplex formation at the GO-CoTPP/PBD interface. Such electroplex emission between electrons and holes is a reason for the low turn-on voltage of the GO-CoTPP-based OLED. Maximum luminance efficiency of 1.43 cd/A with Commission International de l'Eclairage coordinates of 0.33 and 0.40 was achieved at current of 0.02 mA and voltage of 14 V.

Aluminium - Cobalt-Pillared Clay for Dye Filtration Membrane

Science.gov (United States)

Darmawan, A.; Widiarsih

2018-04-01

The manufacture of membrane support from cobalt aluminium pillared clay has been conducted. This research was conducted by mixing a clay suspension with pillared solution prepared from the mixture of Co(NO3)2.6H2O and AlCl3.6H2O. The molar ratio between Al and Co was 75:25 and the ratio of [OH-]/[metal] was 2. The clay suspension was stirred for 24 hours at room temperature, filtered and dried. The dried clay was then calcined at 200°C, 300°C and 400°C with a ramp rate of 2°C/min. Aluminium-cobalt-pillared clay was then characterized by XRD and GSA and moulded become a membrane support for subsequent tests on dye filtration. The XRD analysis showed that basal spacing (d 001) value of aluminium cobalt was 19.49 Å, which was higher than the natural clay of 15.08Å however, the basal spacing decreased with increasing calcination temperature. The result of the GSA analysis showed that the pore diameter of the aluminium cobalt pillared clay membrane was almost the same as that of natural clay that were 34.5Å and 34.2Å, respectively. Nevertheless, the pillared clay has a more uniform pore size distribution. The results of methylene blue filtration measurements demonstrated that the membrane filter support could well which shown by a clear filtrate at all concentrations tested. The value of rejection and flux decreased with the increasing concentration of methylene blue. The values of dye rejection and water flux reached 99.89% and 5. 80 x 10-6 kg min-1, respectively but they decreased with increasing concentration of methylene blue. The results of this study indicates that the aluminium-pillared clay cobalt could be used as membrane materials especially for ultrafiltration.

Fabrication of a PVC membrane samarium(III) sensor based on N,N′,N″-tris(4-pyridyl)trimesic amide as a selectophore

International Nuclear Information System (INIS)

Zamani, Hassan Ali; Naghavi-Reyabbi, Fatemeh; Faridbod, Farnoush; Mohammadhosseini, Majid; Ganjali, Mohammad Reza; Tadjarodi, Azadeh; Rad, Maryam

2013-01-01

A new ion-selective electrode for Sm 3+ ion is described based on the incorporation of N,N′,N″-tris(4-pyridyl)trimesic amide (TPTA) in a poly(vinylchloride) (PVC) matrix. The membrane sensor comprises nitrobenzene (NB) as a plasticizer, and oleic acid (OA) as an anionic additive. The sensor with the optimized composition shows a Nernstian potential response of 19.8 ± 0.5 mV decade −1 over a wide concentration range of 1.0 × 10 −2 and 1 × 10 −6 mol L −1 , with a lower detection limit of 4.7 × 10 −7 mol L −1 and satisfactor applicable pH range of 3.6–9.2. Having a short response time of less than 10 s and a very good selectivity towards the Sm 3+ over a wide variety of interfering cations (e.g. alkali, alkaline earth, transition and heavy metal ions) the sensor seemed to be a promising analytical tool for determination of the Sm 3+ . Hence, it was used as an indicator electrode in the potentiometric titration of samarium ion with EDTA. It was also applied to the direct samarium recovery in binary mixtures. - Highlights: ► A new Sm 3+ -PVC membrane sensor is introduced for determination of Sm 3+ ions in the solutions. ► N,N′,N″-tris(4-pyridyl)trimesic amide was used as a suitable selectophore for samarium sensor. ► Detection limit of the sensor is 4.7 × 10 −7 mol L −1 with a short response time of less than 10 s.

Ligand and Metal Based Multielectron Redox Chemistry of Cobalt Supported by Tetradentate Schiff Bases.

Science.gov (United States)

Andrez, Julie; Guidal, Valentin; Scopelliti, Rosario; Pécaut, Jacques; Gambarelli, Serge; Mazzanti, Marinella

2017-06-28

We have investigated the influence of bound cations on the reduction of cobalt complexes of redox active ligands and explored the reactivity of reduced species with CO 2 . The one electron reduction of [Co II ( R salophen)] with alkali metals (M = Li, Na, K) leads to either ligand-centered or metal-centered reduction depending on the alkali ion. It affords either the [Co I ( R salophen)K] complexes or the [Co II 2 (bis-salophen)M 2 ] (M = Li, Na) dimers that are present in solution in equilibrium with the respective [Co I (salophen)M] complexes. The two electron reduction of [Co II ( OMe salophen)] results in both ligand centered and metal centered reduction affording the Co(I)-Co(II)-Co(I) [Co 3 (tris- OMe salophen)Na 6 (THF) 6 ], 6 complex supported by a bridging deca-anionic tris- OMe salophen 10- ligand where three OMe salophen units are connected by two C-C bonds. Removal of the Na ion from 6 leads to a redistribution of the electrons affording the complex [(Co( OMe salophen)) 2 Na][Na(cryptand)] 3 , 7. The EPR spectrum of 7 suggests the presence of a Co(I) bound to a radical anionic ligand. Dissolution of 7 in pyridine leads to the isolation of [Co I 2 (bis- OMe salophen)Na 2 Py 4 ][Na(cryptand)] 2 , 8. Complex 6 reacts with ambient CO 2 leading to multiple CO 2 reduction products. The product of CO 2 addition to the OMe salophen ligand, [Co( OMe salophen-CO 2 )Na] 2 [Na(cryptand)] 2 , 9, was isolated but CO 3 2- formation in 53% yield was also detected. Thus, the electrons stored in the reversible C-C bonds may be used for the transformation of carbon dioxide.

{Tris[2-(imidazol-2-ylmethyliminoethyl]methylammonium}iron(II tris(perchlorate dihydrate

Directory of Open Access Journals (Sweden)

Greg A. Brewer

2008-01-01

Full Text Available The title complex, [Fe(C19H27N10](ClO43·2H2O, is a new polymorph of an iron(II Schiff base complex of tris(2-aminoethylmethylammonium with imidazole-2-carboxaldehyde. The octahedral FeII atom is bound to three facial imidazole N atoms with average Fe—Nimidazole and Fe—Nimine bond distances of 1.963 (5 and 1.951 (5 Å, respectively. The central N atom of the tripodal ligand is outside the bonding distance at 3.92 Å. The crystal packing is stabilized by the hydrogen-bonding interactions between the two water molecules (acceptor and two of the three imidazole NH groups (donor. The third imidazole NH group (donor forms a hydrogen bond to one of the three perchlorate counter-ions (acceptor.

VIABILITAS SPERMATOZOA KAMBING BOER PASCA PENDINGINAN DAN PEMBEKUAN MENGGUNAKAN PENGENCER DASAR TRIS DENGAN LEVEL TREHALOSA YANG BERBEDA

Directory of Open Access Journals (Sweden)

Nurul Isnaini

2012-04-01

Full Text Available ABSTRAK Penyimpanan semen bisa dilakukan dengan pendinginan atau pembekuan. Setelah pendinginan atau pembekuan viabilitas spermatozoa akan menurun. Untuk dapat mempertahankan viabilitas spermatozoa selama pendinginan atau pembekuan diperlukan krioprotektan dengan level tepat. Trehalosa merupakan krioprotektan ekstraseluler yang mampu menstabilkan membrane dan sebagai anti oksidan bagi spermatozoa selama pendinginan dan pembekuan sehingga diharapkan dapat mempertahankan viabilitas spermatozoa. Masalah dalam penelitian ini adalah bagaimanakah peranan trehalosa pada level yang berbeda dalam pengencer dasar tris mampu menekan penurunan viabilitas spermatozoa kambing Boer selama pendinginan dan pembekuan? Tujuan  dari penelitian ini adalah mengkaji pengaruh berbagai level trehalosa dalam pengencer dasar tris terhadap viabilitas spermatozoa kambing Boer setelah  pendinginan dan pembekuan. Metode penelitian yang digunakan adalah eksperimental laboratorium. Penelitian terdiri atas 2 tahap. Tahap I. Pengaruh level trehalosa dalam pengencer tris terhadap viabilitas spermatozoa kambing Boer setelah pendinginan. Tahap 2. Pengaruh level trehalosa dalam pengencer tris terhadap viabilitas spermatozoa kambing Boer setelah pembekuan. Level trehalosa yang dicobakan pada masing-masing tahap adalah: 1,5%; 2,5% dan 3,5%, dan ulangan: 10 kali. Variabel yang diamati adalah viabilitas spermatozoa. Hasil penelitian menunjukkan bahwa level trehalosa berpengaruh terhadap viabilitas spermatozoa, baik setelah pendinginan maupun pembekuan. Dari hasil penelitian dapat disimpulkan bahwa dalam pendinginan dan pembekuan semen kambing Boer, masing-masing penambahan level 1,5% dan 2,5% dalam pengencer dasar tris menghasilkan viabilitas spermatozoa yang optimal. Dari hasil penelitian disarankan bahwa dalam pendinginan dan pembekuan semen kambing Boer sebaiknya ditambahkan trehalosa masing-masing 1,5% dan 2,5% dalam pengencer dasar tris agar mendapatkan viabilitas spermatozoa yang

Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

Science.gov (United States)

Zelenay, Piotr; Wu, Gang

2014-04-29

A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

Tris-diamine-derived transition metal complexes of flurbiprofen as ...

African Journals Online (AJOL)

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butyrylcholinesterase (BChE) inhibitory activities. Method: Tris-diamine-derived transition metal complexes of Co(II), Ni(II), and Mn(II) were synthesized and characterized ... Conductance measurements indicated that diamine-derived metal complexes of ..... contributes to enhanced biological activity, and provides novel ...

Surprisingly facile CO2 insertion into cobalt alkoxide bonds: A theoretical investigation

Directory of Open Access Journals (Sweden)

Willem K. Offermans

2015-07-01

Full Text Available Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory calculations to elucidate the reaction step of CO2 insertion into cobalt(III–alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III–alkoxide bond of [(2-hydroxyethoxyCoIII(salen(L] complexes (salen = N,N”-bis(salicyliden-1,6-diaminophenyl is exothermic, whereby the exothermicity depends on the trans-ligand L. The more electron-donating this ligand is, the more exothermic the insertion step is. Interestingly, we found that the activation barrier decreases with increasing exothermicity of the CO2 insertion. Hereby, a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy.

Additive Manufacturing: A Novel Method for Fabricating Cobalt-Chromium Removable Partial Denture Frameworks.

Science.gov (United States)

Alifui-Segbaya, Frank; Williams, Robert John; George, Roy

2017-06-01

Additive manufacturing (AM) often referred to as 3D printing (3DP) has shown promise of being significantly viable in the construction of cobalt-chromium removable partial denture (RPD) frameworks. The current paper seeks to discuss AM technologies (photopolymerization processes and selective laser melting) and review their scope. The review also discusses the clinical relevance of cobalt-chromium RPD frameworks. All relevant publications in English over the last 10 years, when the first 3D-printed RPD framework was reported, are examined. The review notes that AM offers significant benefits in terms of speed of the manufacturing processes however cost and other aspects of current technologies remain a hindrance. Copyright© 2017 Dennis Barber Ltd.

Synthesis of new cobalt aluminophosphate framework by opening a cobalt methylphosphonate layered material

Czech Academy of Sciences Publication Activity Database

Zaarour, M.; Pérez, O.; Boullay, P.; Martens, J.; Mihailova, B.; Karaghiosoff, K.; Palatinus, Lukáš; Mintova, S.

2017-01-01

Roč. 19, č. 34 (2017), s. 5100-5105 ISSN 1466-8033 Institutional support: RVO:68378271 Keywords : cobalt aluminophosphate * cobalt methylphosphonate * layered materials * crystallic structure * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.474, year: 2016

Radio cobalt in French rivers

International Nuclear Information System (INIS)

Lambrechts, A.; Baudin-Jaulent, Y.

1996-01-01

The isotopes 58 and 60 of cobalt present in liquid wastes from nuclear plants or from fuel reprocessing plant of Marcoule are fixed in the different compartments of French rivers. The activity levels of radio-cobalt vary according to the sampled compartments nature (bryophyta > immersed plants > sediment > fish). Elsewhere, laboratory experimentations show that the contamination of fish occurs essentially from the water way rather than from food. Cobalt is mainly fixed by kidneys; muscles is no more than 30 % of the total fish activity. (author)

Tuning the electrochemistry of homoleptic cobalt 4,4′-disubstituted-2,2′-bipyridine redox mediators

International Nuclear Information System (INIS)

Nolan, Jesse P.; Jones, Timothy W.; Donne, Scott W.; Wilson, Gregory J.

2013-01-01

Highlights: • Cobalt(II) tris(2,2′-bipyridine) complexes were prepared with electron withdrawing or donating groups in the ligand 4 and 4′ positions. • The formal potential of the redox couples was tuned with the Hammett Parameter of the substituent. • Substitution also leads to sluggish oxidation kinetics, as observed with decreased heterogeneous rate constant and transfer coefficient >0.5. Reduction kinetics remained facile. -- Abstract: The electrochemistry of a series of Co(II) tris(4,4′-disubstituted-2,2′-bipyridine) hexafluorophosphate complexes was investigated in acetonitrile, and compared to the parent, un-substituted 2,2′-bipyridine complex. The introduction of an electron-withdrawing halogen substituent increased the formal redox potential of the couple by 190–270 mV, in the order of F > Cl > Br > I. Substitution with electron-donating tert-butyl and methoxy groups acted as electron donating groups, and decreased the formal potential by 150–190 mV. Substitution in the 4,4′ positions, irrespective of electron withdrawing or donating character, also imparted an asymmetry in the anodic peak in the cyclic voltammograms, where the oxidation process became more sluggish than the corresponding reduction. Kinetics of Co(II) oxidation was evaluated by Koutecký–Levich analysis at a rotating Pt disc, revealing superior oxidation kinetics of the un-substituted 2,2′-bipyridine complex by up to an order of magnitude or larger. The anodic transfer coefficients were also extracted from this analysis, revealing ideal α = 0.50 for the parent complex, to 0.70 ≤ α ≤ 0.88 for complexes with substituted ligands

Hydrothermal synthesis, characterization, and magneticproperties of cobalt chromite nanoparticles

Czech Academy of Sciences Publication Activity Database

Zákutná, Dominika; Repko, A.; Matulková, I.; Nižňanský, Daniel; Ardu, A.; Cannas, C.; Mantlíková, Alice; Vejpravová, Jana

2014-01-01

Roč. 16, č. 2 (2014), 1-14 ISSN 1388-0764 R&D Projects: GA ČR GAP108/10/1250 Institutional support: RVO:68378271 ; RVO:61388980 Keywords : cobalt chromite * hydrothermal method * nanoparticles * size effect * multiferroic materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.184, year: 2014

Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

International Nuclear Information System (INIS)

Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V.

2012-01-01

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity

Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

Energy Technology Data Exchange (ETDEWEB)

Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V. [Univ. of Madras, Madras (India)

2012-11-15

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

Pengaruh Kepuasan Dan Kepercayaan Terhadap Keputusan Pembelian Ulang Pada Depot Air Minum Tris Water Reverse Osmosis System (Ro)

OpenAIRE

Fitria, Ika

2011-01-01

Kind of this survey is asociative survey which watch influence of customer satisfaction and trust to re-purchase decision on Depot Air Minum Tris Water Reverse Osmosis System (RO) and test of hypothesis use Multiple Linear Regression Analysist on α=5%. This survey used SPSS 16.00 version for windows. Research population is consumers of Depot Air Minum Tris Water Reverse Osmosis System (RO). Sample was used in this survey from customers of Depot Air Minum Tris Water Reverse Osmosis System (RO)...

Molecular mechanics calculations on cobalt phthalocyanine dimers

NARCIS (Netherlands)

Heuts, J.P.A.; Schipper, E.T.W.M.; Piet, P.; German, A.L.

1995-01-01

In order to obtain insight into the structure of cobalt phthalocyanine dimers, molecular mechanics calculations were performed on dimeric cobalt phthalocyanine species. Molecular mechanics calculations are first presented on monomeric cobalt(II) phthalocyanine. Using the Tripos force field for the

Impurity diffusion of cobalt in plutonium

International Nuclear Information System (INIS)

Charissoux, Christian; Calais, Daniel.

1975-01-01

The sectioning method for investigation of the impurity diffusion of 60 Co in the fcc and bcc phases of plutonium gives the following results: 344-426 deg C: D=1.2x10 -2 exp(-12700/RT)cm 2 /s in delta Pu(fcc); 484-621 deg C: D=1.4x10 -3 exp(-9900/RT)cm 2 /s in epsilon Pu(bcc). Cobalt is a fast diffuser in plutonium; the diffusion coefficient being unaffected by phase changes delta'→delta; delta'→epsilon, the diffusion mechanism is probably dissociative in both phases, the solute becoming interstitial by: solute (substitution) reversible solute (interstitial) + vacancy [fr

Basel III D: Swiss Finish to Basel III

OpenAIRE

Christian M. McNamara; Natalia Tente; Andrew Metrick

2014-01-01

After the Basel Committee on Banking Supervision (BCBS) introduced the Basel III framework in 2010, individual countries confronted the question of how best to implement the framework given their unique circumstances. Switzerland, with a banking industry that is both heavily concentrated and very large relative to the size of its overall economy, faced a special challenge. It ultimately adopted what is sometimes referred to as the “Swiss Finish” to Basel III – enhanced requirements applicable...

Synthesis and anion binding studies of tris(3-aminopropyl)amine-based tripodal urea and thiourea receptors: Proton transfer-induced selectivity for hydrogen sulfate over sulfate.

Science.gov (United States)

Khansari, Maryam Emami; Johnson, Corey R; Basaran, Ismet; Nafis, Aemal; Wang, Jing; Leszczynski, Jerzy; Hossain, Md Alamgir

2015-01-01

Tris(3-aminopropyl)amine-based tripodal urea and thiourea receptors, tris([(4-cyanophenyl)amino]propyl)urea ( L1 ) and tris([(4-cyanophenyl)amino]propyl)thiourea ( L2 ), have been synthesized and their anion binding properties have been investigated for halides and oxoanions. As investigated by 1 H NMR titrations, each receptor binds an anion with a 1:1 stoichiometry via hydrogen-bonding interactions (NH⋯anion), showing the binding trend in the order of F - > H 2 PO 4 - > HCO 3 - > HSO 4 - > CH 3 COO - > SO 4 2- > Cl - > Br - > I in DMSO- d 6 . The interactions of the receptors were further studied by 2D NOESY, showing the loss of NOESY contacts of two NH resonances for the complexes of F - , H 2 PO 4 - , HCO 3 - , HSO 4 - or CH 3 COO - due to the strong NH⋯anion interactions. The observed higher binding affinity for HSO 4 - than SO 4 2- is attributed to the proton transfer from HSO 4 - to the central nitrogen of L1 or L2 which was also supported by the DFT calculations, leading to the secondary acid-base interactions. The thiourea receptor L2 has a general trend to show a higher affinity for an anion as compared to the urea receptor L1 for the corresponding anion in DMSO- d 6 . In addition, the compound L2 has been exploited for its extraction properties for fluoride in water using a liquid-liquid extraction technique, and the results indicate that the receptor effectively extracts fluoride from water showing ca. 99% efficiency (based on L2 ).

AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

DEFF Research Database (Denmark)

1997-01-01

An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...

Synthesis and structural characterization of two cobalt phosphites: 1-D (H3NC6H4NH3)Co(HPO3)2 and 2-D (NH4)2Co2(HPo3)3

International Nuclear Information System (INIS)

Cheng, C.-C.; Chang, W.-K.; Chiang, R.-K.; Wang, S.-L.

2010-01-01

Two new cobalt phosphites, (H 3 NC 6 H 4 NH 3 )Co(HPO 3 ) 2 (1) and (NH 4 ) 2 Co 2 (HPO 3 ) 3 (2), have been synthesized and characterized by single-crystal X-ray diffraction. All the cobalt atoms of 1 are in tetrahedral CoO 4 coordination. The structure of 1 comprises twisted square chains of four-rings, which contain alternating vertex-shared CoO 4 tetrahedra and HPO 3 groups. These chains are interlinked with trans-1,4-diaminocyclohexane cations by hydrogen bonds. The 2-D structure of 2 comprises anionic complex sheets with ammonium cations present between them. An anionic complex sheet contains three-deck phosphite units, which are interconnected by Co 2 O 9 to form complex layers. Magnetic susceptibility measurements of 1 and 2 showed that they have a weak antiferromagnetic interaction. - Graphical abstract: The 2-D structure of (NH 4 ) 2 Co 2 (HPO 3 ) 3 comprises anionic complex sheets with ammonium cations present between them. An anionic complex sheet contains three-deck phosphite units, which are interconnected by dimmeric Co 2 O 9 to form complex layers.

Cyanide Scavenging by a Cobalt Schiff-Base Macrocycle: A Cost-Effective Alternative to Corrinoids.

Science.gov (United States)

Lopez-Manzano, Elisenda; Cronican, Andrea A; Frawley, Kristin L; Peterson, Jim; Pearce, Linda L

2016-06-20

The complex of cobalt(II) with the ligand 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]heptadeca-1(17)2,11,13,15-pentaene (CoN4[11.3.1]) has been shown to bind two molecules of cyanide in a cooperative fashion with an association constant of 2.7 (±0.2) × 10(5). In vivo, irrespective of whether it is initially administered as the Co(II) or Co(III) cation, EPR spectroscopic measurements on blood samples show that at physiological levels of reductant (principally ascorbate) CoN4[11.3.1] becomes quantitatively reduced to the Co(II) form. However, following addition of sodium cyanide, a dicyano Co(III) species is formed, both in blood and in buffered aqueous solution at neutral pH. In keeping with other cobalt-containing cyanide-scavenging macrocycles like cobinamide and cobalt(III) meso-tetra(4-N-methylpyridyl)porphine, we found that CoN4[11.3.1] exhibits rapid oxygen turnover in the presence of the physiological reductant ascorbate. This behavior could potentially render CoN4[11.3.1] cytotoxic and/or interfere with evaluations of the antidotal capability of the complex toward cyanide through respirometric measurements, particularly since cyanide rapidly inhibits this process, adding further complexity. A sublethal mouse model was used to assess the effectiveness of CoN4[11.3.1] as a potential cyanide antidote. The administration of CoN4[11.3.1] prophylactically to sodium cyanide-intoxicated mice resulted in the time required for the surviving animals to recover from "knockdown" (unconsciousness) being significantly decreased (3 ± 2 min) compared to that of the controls (22 ± 5 min). All observations are consistent with the demonstrated antidotal activity of CoN4[11.3.1] operating through a cyanide-scavenging mechanism, which is associated with a Co(II) → Co(III) oxidation of the cation. To test for postintoxication neuromuscular sequelae, the ability of mice to remain in position on a rotating cylinder (RotaRod test) was assessed during and after recovery

Phosphorus introduction mechanism in electrodeposited cobalt films

International Nuclear Information System (INIS)

Kravtchenko, Jean-Francois

1973-01-01

The cathodic reduction of hypophosphite, phosphite and phosphate ions was studied using chrono-potentiometry and voltammetry. Then cobalt was deposited at constant current from a bath containing one of these three compounds. The current, while giving an electrodeposition of cobalt, also enhances at the same time a chemical deposition of cobalt. It is shown that high coercive forces in cobalt films are much more related to this chemical deposition than to the simple fact that the films contain some phosphorus. (author) [fr

Unusual stoichiometry control in the atomic layer deposition of manganese borate films from manganese bis(tris(pyrazolyl)borate) and ozone

Energy Technology Data Exchange (ETDEWEB)

Klesko, Joseph P.; Bellow, James A.; Saly, Mark J.; Winter, Charles H., E-mail: chw@chem.wayne.edu [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States); Julin, Jaakko; Sajavaara, Timo [Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

2016-09-15

The atomic layer deposition (ALD) of films with the approximate compositions Mn{sub 3}(BO{sub 3}){sub 2} and CoB{sub 2}O{sub 4} is described using MnTp{sub 2} or CoTp{sub 2} [Tp = tris(pyrazolyl)borate] with ozone. The solid state decomposition temperatures of MnTp{sub 2} and CoTp{sub 2} are ∼370 and ∼340 °C, respectively. Preparative-scale sublimations of MnTp{sub 2} and CoTp{sub 2} at 210 °C/0.05 Torr afforded >99% recoveries with <0.1% nonvolatile residues. Self-limited ALD growth was demonstrated at 325 °C for MnTp{sub 2} or CoTp{sub 2} with ozone as the coreactant. The growth rate for the manganese borate process was 0.19 Å/cycle within the ALD window of 300–350 °C. The growth rate for the cobalt borate process was 0.39–0.42 Å/cycle at 325 °C. X-ray diffraction of the as-deposited films indicated that they were amorphous. Atomic force microscopy of 35–36 nm thick manganese borate films grown within the 300–350 °C ALD window showed root mean square surface roughnesses of 0.4–0.6 nm. Film stoichiometries were assessed by x-ray photoelectron spectroscopy and time of flight-elastic recoil detection analysis. The differing film stoichiometries obtained from the very similar precursors MnTp{sub 2} and CoTp{sub 2} are proposed to arise from the oxidizing ability of the intermediate high valent manganese oxide layers and lack thereof for cobalt.

Cobalt reduction of NSSS valve hardfacings for ALARA

Energy Technology Data Exchange (ETDEWEB)

Kim, Joo Hak; Lee, Sang Sub [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1994-07-01

This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author).

Cobalt reduction of NSSS valve hardfacings for ALARA

International Nuclear Information System (INIS)

Kim, Joo Hak; Lee, Sang Sub

1994-07-01

This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author)

Fluoride Bridges as Structure-Directing Motifs in 3d-4f Cluster Chemistry

DEFF Research Database (Denmark)

Birk, Torben; Pedersen, Kasper; Thuesen, Christian Aa.

2012-01-01

The use of kinetically robust chromium(III) fluorido complexes as synthons for mixed 3d-4f clusters is reported. The tendency toward linear {CrIII–F–LnIII} units dictates the cluster topology. Specifically, we show that reaction of cis-[CrIIIF2(NN)2]NO3 (NN = 1,10-phenanthroline (“phen”) or 2......-nuclear complex and fac-[CrIIIF3L′], with L′ = 1,1,1-tris-((methylamino)methylethane) (“Me3tame”), reacts with [Ln(hfac)3(H2O)2] (hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone) to yield an isostructural series of {Ln3Cr2} (10–14) trigonal bipyramids with no central ligand. The formation of the latter is accompanied...... by a partial solvolysis of the Cr(III) precursor but without formation of insoluble LnF3. The magnetic properties of the gadolinium containing clusters allow quantification of fluoride-mediated, antiferromagnetic Gd–Cr exchange interactions of magnitude between 0.14 cm–1 and 0.71 cm–1 (Ĥ = J12Ŝ1·Ŝ2...

The Role of External Inputs and Internal Cycling in Shaping the Global Ocean Cobalt Distribution: Insights From the First Cobalt Biogeochemical Model

Science.gov (United States)

Tagliabue, Alessandro; Hawco, Nicholas J.; Bundy, Randelle M.; Landing, William M.; Milne, Angela; Morton, Peter L.; Saito, Mak A.

2018-04-01

Cobalt is an important micronutrient for ocean microbes as it is present in vitamin B12 and is a co-factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is compared to biological demands, cobalt emerges as being depleted in seawater, pointing to a potentially important limiting role. To properly account for the potential biological role for cobalt, there is therefore a need to understand the processes driving the biogeochemical cycling of cobalt and, in particular, the balance between external inputs and internal cycling. To do so, we developed the first cobalt model within a state-of-the-art three-dimensional global ocean biogeochemical model. Overall, our model does a good job in reproducing measurements with a correlation coefficient of >0.7 in the surface and >0.5 at depth. We find that continental margins are the dominant source of cobalt, with a crucial role played by supply under low bottom-water oxygen conditions. The basin-scale distribution of cobalt supplied from margins is facilitated by the activity of manganese-oxidizing bacteria being suppressed under low oxygen and low temperatures, which extends the residence time of cobalt. Overall, we find a residence time of 7 and 250 years in the upper 250 m and global ocean, respectively. Importantly, we find that the dominant internal resupply process switches from regeneration and recycling of particulate cobalt to dissolution of scavenged cobalt between the upper ocean and the ocean interior. Our model highlights key regions of the ocean where biological activity may be most sensitive to cobalt availability.

An extremely bulky tris(pyrazolyl)methanide: a tridentate ligand for the synthesis of heteroleptic magnesium(II) and ytterbium(II) alkyl, hydride, and iodide complexes.

Science.gov (United States)

Lalrempuia, Ralte; Stasch, Andreas; Jones, Cameron

2015-02-01

The tris(pyrazolyl)methane compound HC(3-Ad-5-Mepz)3 [1, 3-Ad-5-Mepz=3-(1-adamantyl)-5-methylpyrazolyl] and its regioisomer, HC(3-Ad-5-Mepz)2 (3-Me-5-Adpz), were synthesized and crystallographically characterized. Deprotonation of 1 with MeLi afforded the lithium complex [{κ(3) -N-C(3-Ad-5-Mepz)3 }Li(thf)], which incorporates a tris(pyrazolyl)methanide ligand of unprecedented bulk. Reaction of 1 with MeMgI gave the ionic coordination complex [{κ(3) -N-HC(3-Ad-5-Mepz)3 }MgMe]I, which was readily deprotonated to afford the neutral compound [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgMe]. The related magnesium butyl compound [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgBu] was prepared from the reaction of 1 and MgBu2 . Treating this with LiAlH4 or LiAlD4 led to rare examples of terminal magnesium hydride/deuteride complexes, [{κ(3) -N-C(3-Ad-5-Mepz)3 }MgH/D]. All neutral magnesium alkyl and hydride compounds were crystallographically authenticated. Reaction of [{κ(3) κN-C(3-Ad-5-Mepz)3 }Li(thf)] with [YbI2 (thf)2 ] yielded the first structurally characterized f-block tris(pyrazolyl)methanide complex, [{κ(3) -N-C(3-Ad-5-Mepz)3 }YbI(thf)]. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2D and 3D organisation of nano-particles: synthesis and specific properties

International Nuclear Information System (INIS)

Taleb, Abdelhafed

1998-01-01

The first part of this research thesis addresses the synthesis of nano-particles of silver and cobalt in the inverse micellar system, and highlights the feasibility of two- and three-dimensional structures of these particles. The author first presents the micellar system (micro-emulsions, surfactant, properties of inverse micelles, functionalized inverse micelles, application to the synthesis of nano-particles), and then reports the study of the synthesis and organisation of colloids in 2D and 3D. He also reports the study of optical properties of metallic colloids: free electron approximation, optical properties of electron gases, optical properties of colloids, optical response of two-dimensional and three-dimensional nano-structures. The magnetic properties of colloids are then studied: magnetism of the massive metallic state, magnetic properties of nano-particles (influence of size, interactions and field, notions of magnetic order and disorder), effect of organisation. The second part of this thesis is made of a set of published articles: Synthesis of highly mono-disperse silver nano-particles from AOT reverse micelles (a way to 2D and 3D self-organisation), Optical properties of self-assembled 2D and 3D super-lattices of silver nano-particles, Collective optical properties of silver nano-particles organised in 2D super-lattices, Self assembled in 2D cobalt nano-sized particles, Self organisation of magnetic nano-sized cobalt particles, Organisation in 2D cobalt nano-particles (synthesis, characterization and magnetic properties) [fr

Accumulation of cobalt by cephalopods

International Nuclear Information System (INIS)

Nakahara, Motokazu

1981-01-01

Accumulation of cobalt by cephalopod mollusca was investigated by radiotracer experiments and elemental analysis. In the radiotracer experiments, Octopus vulgaris took up cobalt-60 from seawater fairly well and the concentration of the nuclide in whole body attained about 150 times the level of seawater at 25th day at 20 0 C. Among the tissues and organs measured, branchial heart which is the specific organ of cephalopods showed the highest affinity for the nuclide. The organ accumulated about 50% of the radioactivity in whole body in spite of its little mass as 0.2% of total body weight. On the other hand, more than 90% of the radioactivity taken up from food (soft parts of Gomphina melanaegis labelled with cobalt-60 previously in an aquarium) was accumulated in liver at 3rd day after the single administration and then the radioactivity in the liver seemed to be distributed to other organs and tissues. The characteristic elution profiles of cobalt-60 was observed for each of the organs and tissues in Sephadex gel-filtration experiment. It was confirmed by the gel-filtration that most of cobalt-60 in the branchial heart was combined with the constituents of low molecular weights. The average concentration of stable cobalt in muscle of several species of cephalopods was 5.3 +- 3.0 μg/kg wet and it was almost comparable to the fish muscle. On the basis of soft parts, concentration of the nuclide closed association among bivalve, gastropod and cephalopod except squid that gave lower values than the others. (author)

Cobalt-free nickel-base superalloys

International Nuclear Information System (INIS)

Koizumi, Yutaka; Yamazaki, Michio; Harada, Hiroshi

1979-01-01

Cobalt-free nickel-base cast superalloys have been developed. Cobalt is considered to be a beneficial element to strengthen the alloys but should be eliminated in alloys to be used for direct cycle helium turbine driven by helium gas from HTGR (high temp. gas reactor). The elimination of cobalt is required to avoid the formation of radioactive 60 Co from the debris or scales of the alloys. Cobalt-free alloys are also desirable from another viewpoint, i.e. recently the shortage of the element has become a serious problem in industry. Cobalt-free Mar-M200 type alloys modified by the additions of 0.15 - 0.2 wt% B and 1 - 1.5 wt% Hf were found to have a creep rupture strength superior or comparable to that of the original Mar-M200 alloy bearing cobalt. The ductility in tensile test at 800 0 C, as cast or after prolonged heating at 900 0 C (the tensile test was done without removing the surface layer affected by the heating), was also improved by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf. The morphology of grain boundaries became intricated by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf, to such a degree that one can hardly distinguish grain boundaries by microscopes. The change in the grain boundary morphology was considered, as suggested previously by one of the authors (M.Y.), to be the reason for the improvements in the creep rupture strength and tensile ductility. (author)

Cobalt-60 production in CANDU power reactors

International Nuclear Information System (INIS)

Malkoske, G.R.; Norton, J.L.; Slack, J.

2002-01-01

MDS Nordion has been supplying cobalt-60 sources to industry for industrial and medical purposes since 1946. These cobalt-60 sources are used in many market and product segments, but are primarily used to sterilize single-use medical products including; surgical kits, gloves, gowns, drapes, and cotton swabs. Other applications include sanitization of cosmetics, microbial reduction of pharmaceutical raw materials, and food irradiation. The technology for producing the cobalt-60 isotope was developed by MDS Nordion and Atomic Energy of Canada Limited (AECL) almost 55 years ago using research reactors at the AECL Chalk River Laboratories in Ontario, Canada. The first cobalt-60 source produced for medical applications was manufactured by MDS Nordion and used in cancer therapy. The benefits of cobalt-60 as applied to medical product manufacturing, were quickly realized and the demand for this radioisotope quickly grew. The same technology for producing cobalt-60 in research reactors was then designed and packaged such that it could be conveniently transferred to a utility/power reactor. In the early 1970's, in co-operation with Ontario Power Generation (formerly Ontario Hydro), bulk cobalt-60 production for industrial irradiation applications was initiated in the four Pickering A CANDU reactors. As the demand and acceptance of sterilization of medical products grew, MDS Nordion expanded its bulk supply by installing the proprietary Canadian technology for producing cobalt-60 in additional CANDU reactors. CANDU is unique among the power reactors of the world, being heavy water moderated and fuelled with natural uranium. They are also designed and supplied with stainless steel adjusters, the primary function of which is to shape the neutron flux to optimize reactor power and fuel bum-up, and to provide excess reactivity needed to overcome xenon-135 poisoning following a reduction of power. The reactor is designed to develop full power output with all of the adjuster

Alfven wave stability in D-III-D

International Nuclear Information System (INIS)

Campbell, R.B.; Samec, T.K.

1989-09-01

Within the framework of the global Alfven eigenmode theory in a cylindrical background plasma, I examine the excitation of global Alfven eigenmodes by intense neutral beam injection in the D III-D tokamak operating at General Atomics. I have considered two separate sets of experimental conditions, a ''low power'' set of cases using 10MW of hydrogen beams, and a ''high power'' shot of 20MW of deuterium beams. My results are particularly sensitive to the background density profile. For parabolic background density profiles, n 0 x (1 - (r/a) 2 ), I have determined that the plasma is stable to all toroidal and poloidal mode numbers for both high and low power cases. For density profiles which are of the form n 0 x (1 - (r/a) 2 ) 1/2 , for the same n 0 , my calculation indicates that the m = -1, l = 0 mode is unstable in each case. The high power case has a considerably higher growth rate at the baseline conditions, which motivated me to study this case more extensively. The results are also sensitive to the beam source radial scalelength, L s , and the electron temperature T e . By narrowing the source from the baseline 36 cm to 20 cm, the growth rate of the (0,-1) actually decreases, but the (0,-2) mode appears with a substantial growth rate. If the source could be made even narrower, L s ∼ 10 cm, the (1,-1) mode would appear, also with a large growth rate. 12 refs., 16 figs., 6 tabs

Metallogels derived from silver coordination polymers of C3-symmetric tris(pyridylamide) tripodal ligands: synthesis of Ag nanoparticles and catalysis.

Science.gov (United States)

Paul, Mithun; Sarkar, Koushik; Dastidar, Parthasarathi

2015-01-02

By applying a recently developed crystal engineering rationale, four C3 symmetric tris(pyridylamide) ligands namely 1,3,5-tris(nicotinamidomethyl)-2,4,6-triethylbenzene, 1,3,5-tris(isonicotinamidomethyl)-2,4,6-triethylbenzene, 1,3,5-tris(nicotinamidomethyl)-2,4,6-trimethylbenzene, and 1,3,5-tris(isonicotinamidomethyl)-2,4,6-trimethylbenzene, which contain potential hydrogen-bonding sites, were designed and synthesized for generating Ag(I) coordination polymers and coordination-polymer-based gels. The coordination polymers thus obtained were characterized by single-crystal X-ray diffraction. The silver metallogels were characterized by transmission electron microscopy (TEM) and dynamic rheology. Upon exposure to visible light, these silver metallogels produced silver nanoparticles (AgNPs), which were characterized by TEM, powder X-ray diffraction, energy dispersive X-ray and X-ray photoelectron spectroscopy. These NPs were found to be effectively catalyzed the reduction of 4-nitrophenolate to 4-aminophenolate without the use of any exogenous reducing agent. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Palladium-cobalt particles as oxygen-reduction electrocatalysts

Science.gov (United States)

Adzic, Radoslav [East Setauket, NY; Huang, Tao [Manorville, NY

2009-12-15

The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

Removal of Cobalt Ions by Precipitate Foam Flotation

Energy Technology Data Exchange (ETDEWEB)

Jung, In Ha; Lee, Jung Won [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-09-30

Simulated waste liquid containing 50 ppm cobalt ion was tested by precipitate flotation using a sodium lauryl sulfate as a collector. The effects of initial cobalt ion concentration, pH, surfactant concentration, flotation time, gas flow rate and foreign ions on removal efficiency of cobalt ion were studied. Pretreatment of the waste liquid with 35% H{sub 2}O{sub 2} prior to precipitate flotation made shift of optimal flotation pH from the strong alkalinity to weak alkaline range and made a favorable flotation of cobalt ion in wide range of pH. For the result of this experiment, 99.8% removal efficiency was obtained on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, flotation time 30 min. The simulate ion was formed to be the most harmful ion against removal of cobalt by precipitate flotation of the species which were tested. The presence of 0.1 M of SO{sub 4}{sup 2-} ion decreased removal efficiency of cobalt to 90% while the cobalt were almost entirely removed in the absence of sulfate ion. (author). 11 refs., 8 figs.

Cobalt: for strength and color

Science.gov (United States)

Boland, Maeve A.; Kropschot, S.J.

2011-01-01

Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

Tris{2-[(3-thienylmethylideneamino]ethyl}amine

Directory of Open Access Journals (Sweden)

Muhammet Işıklan

2010-11-01

Full Text Available The title compound, C21H24N4S3, is a tripodal Schiff base that was obtained from the reaction of tris(2-aminoethylamine (tren and thiophene-3-carbaldehyde. The compound forms a cavity with approximate C3 symmetry. One of the thiophene units is disordered in a 0.764 (2:0.236 (2 ratio. In the crystal, the three thiophene ligands are involved in intramolecular C—H...π interactions and the molecules are connected by C—H...N interactions, forming hydrogen-bonded chains.

Effects of cobalt in nickel-base superalloys

Science.gov (United States)

Tien, J. K.; Jarrett, R. N.

1983-01-01

The role of cobalt in a representative wrought nickel-base superalloy was determined. The results show cobalt affecting the solubility of elements in the gamma matrix, resulting in enhanced gamma' volume fraction, in the stabilization of MC-type carbides, and in the stabilization of sigma phase. In the particular alloy studied, these microstructural and microchemistry changes are insufficient in extent to impact on tensile strength, yield strength, and in the ductilities. Depending on the heat treatment, creep and stress rupture resistance can be cobalt sensitive. In the coarse grain, fully solutioned and aged condition, all of the alloy's 17% cobalt can be replaced by nickel without deleteriously affecting this resistance. In the fine grain, partially solutioned and aged condition, this resistance is deleteriously affected only when one-half or more of the initial cobalt content is removed. The structure and property results are discussed with respect to existing theories and with respect to other recent and earlier findings on the impact of cobalt, if any, on the performance of nickel-base superalloys.

Cryosurvival of goat spermatozoa in tris-egg yolk extender ...

African Journals Online (AJOL)

The effect of melatonin supplementation in semen extenders on cryosurvival of spermatozoa obtained from West African Dwarf (WAD) goat bucks was studied. Tris-egg yolk extenders supplemented with different levels of melatonin (0, 2, 4, 6 and 8 mM) were diluted with semen samples. The diluted semen samples were ...

Highly efficient red phosphorescent Ir(III) complexes for organic light- emitting diodes based on aryl(6-arylpyridin-3-yl)methanone ligands

Energy Technology Data Exchange (ETDEWEB)

Kang, Hyun Ju; Lee, Kum Hee [Department of Chemistry, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Lee, Seok Jae; Seo, Ji Hyun [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@wow.hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

2011-07-29

A series of phosphorescent Ir(III) complexes 1-4 were synthesized based on aryl(6-arylpyridin-3-yl)methanone ligands, and their photophysical and electroluminescent properties were characterized. Multilayer devices with the configuration, Indium tin oxide/4,4',4''-tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine (60 nm)/4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (20 nm)/Ir(III) complexes doped in N,N'-dicarbazolyl-4,4'-biphenyl (30 nm, 8%)/2,9-dimethyl-4,7-diphenyl-phenathroline (10 nm)/tris(8-hydroxyquinoline)-aluminum (20 nm)/lithium quinolate (2 nm)/ Al (100 nm), were fabricated. Among these, the device employing complex 2 as a dopant exhibited efficient red emission with a maximum luminance, luminous efficiency, power efficiency and quantum efficiency of 16200 cd/m{sup 2} at 14.0 V, 12.20 cd/A at 20 mA/cm{sup 2}, 4.26 lm/W and 9.26% at 20 mA/cm{sup 2}, respectively, with Commission Internationale de l'Enclairage coordinates of (0.63, 0.37) at 12.0 V.

(Tris{2-[(5-hydroxypyridin-2-yl-κNmethylideneimino-κN]ethyl}aminezinc dinitrate

Directory of Open Access Journals (Sweden)

Maksym Seredyuk

2011-12-01

Full Text Available In the complex cation of the title compound, [Zn(C24H27N7O3](NO32, the tripodal tris{[2-(5-hydroxypyridin-2-ylmethylideneimino]ethyl}amine ligand is coordinated to the Zn atom through the three pyridine and three imino N atoms. The coordination sphere of the Zn atom is based on an octahedron with a significant distortion towards trigonal prismatic, the twist angle being 45.58 (9°. The crystal packing is formed by L and D antipodes arranged in layers disposed parallel to the b axis. Strong O—H...O hydrogen bonding exists between the hydroxy groups of the ligand and the nitrate anion.

Cobalt: A vital element in the aircraft engine industry

Science.gov (United States)

Stephens, J. R.

1981-01-01

Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

Tetraammine(carbonato-κ(2) O,O')cobalt(III) perchlorate.

Science.gov (United States)

Mohan, Singaravelu Chandra; Jenniefer, Samson Jegan; Muthiah, Packianathan Thomas; Jothivenkatachalam, Kandasamy

2013-01-01

In the title complex, [Co(CO3)(NH3)4]ClO4, both the cation and anion lie on a mirror plane. The Co(III) ion is coordinated by two NH3 ligands and a chelating carbonato ligand in the equatorial sites and by two NH3 groups in the axial sites, forming a distorted octa-hedral geometry. In the crystal, N-H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

Nickel, cobalt, and their alloys

CERN Document Server

2000-01-01

This book is a comprehensive guide to the compositions, properties, processing, performance, and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the ASM Handbook series, as well as new or updated coverage in many areas in the nickel, cobalt, and related industries.

Cobalt sorption onto Savannah River Plant soils

International Nuclear Information System (INIS)

Hoeffner, S.L.

1985-06-01

A laboratory study of cobalt-60 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that cobalt sorption is most strongly a function of pH. Over a pH range of 2 to 9, the distribution coefficient ranged from 2 to more than 10,000 mL/g. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence cobalt sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect on cobalt sorption. Ferrous ion, added to groundwater to simulate the condition of water at the bottom of the waste trenches, accounts for part of the decrease in cobalt sorption observed with trench waters. 17 refs., 3 figs., 4 tabs

Normal coordinate analysis and quantum chemical study of tris(p ...

Indian Academy of Sciences (India)

The crystal structure of the title compound tris(p-flourophenyl)antimony di(N- phenylglycinate) ..... in the present compound and presence of nitrogen atoms as well. ... [7] L Yu, Y Q Ma, G C Wang and J S Li, Heteroatom Chem. 15, 32 (2004).

Growth and characterization of thin oriented Co3O4 (111) films obtained by decomposition of layered cobaltates NaxCoO2

Czech Academy of Sciences Publication Activity Database

Buršík, Josef; Soroka, Miroslav; Kužel, R.; Mika, Filip

2015-01-01

Roč. 227, JUL (2015), s. 17-24 ISSN 0022-4596 R&D Projects: GA ČR GA13-03708S; GA ČR(CZ) GA14-18392S Institutional support: RVO:61388980 ; RVO:68081731 Keywords : Cobalt oxides * Spinels * Layered cobaltates * Chemical solution deposition * Thin films Subject RIV: CA - Inorganic Chemistry; JA - Electronics ; Optoelectronics, Electrical Engineering (UPT-D) Impact factor: 2.265, year: 2015

Transport of cobalt-60 industrial radiation sources

Science.gov (United States)

Kunstadt, Peter; Gibson, Wayne

This paper will deal with safety aspects of the handling of Cobalt-60, the most widely used industrial radio-isotope. Cobalt-60 is a man-made radioisotope of Cobalt-59, a naturally occurring non radioactive element, that is made to order for radiation therapy and a wide range of industrial processing applications including sterilization of medical disposables, food irradiation, etc.

Theoretical study on decay of the 4d core-excited states of Cs III

International Nuclear Information System (INIS)

Ding Xiaobin; Dong Chenzhong; Fritzsche, Stephan

2008-01-01

In a recent XUV photoabsorption spectrum of Cs III ions by Cummings and O'Sullivan [2001 J. Phys. B 34 199], rather large linewidths were found for the 4d 9 5s 2 5p 6 – 4d 10 5s 2 5p 5 transition which are quite in disagreement with corresponding quasi-relativistic multiconfiguration Hartree–Fock (MCHF) calculation. In the present work, a detailed multiconfiguration Dirac-Fock study has been carried out to explore this discrepancy. Owing to the detailed consideration of electron correlation effects, some 'forbidden' Auger decay channels, such as 4d 10 5s 2 5p 3 5d and 4d 10 5s 0 5p 6 , would become 'open'. As a result, remarkable improvement of the linewidths has been obtained in our calculation. Furthermore, the theoretical Auger spectrum of the 4d 9 5s 2 5p 6 core-excited states of Cs III ions is given in the present work

A new three-dimensional cobalt phosphate: Co5(OH2)4(HPO4)2(PO4)2

International Nuclear Information System (INIS)

Han Zhangang; Tian Aixiang; Peng Jun; Zhai Xueliang

2006-01-01

A three-dimensional (3D) cobalt phosphate: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs. - Graphical abstract: A 3D cobalt phosphate with a neutral framework: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized and characterized. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. Its magnetic property was researched

Tetraammine(carbonato-κ2 O,O′)cobalt(III) perchlorate

Science.gov (United States)

Mohan, Singaravelu Chandra; Jenniefer, Samson Jegan; Muthiah, Packianathan Thomas; Jothivenkatachalam, Kandasamy

2013-01-01

In the title complex, [Co(CO3)(NH3)4]ClO4, both the cation and anion lie on a mirror plane. The CoIII ion is coordinated by two NH3 ligands and a chelating carbonato ligand in the equatorial sites and by two NH3 groups in the axial sites, forming a distorted octa­hedral geometry. In the crystal, N—H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network. PMID:24109252

Chromium(III)-trisoxalate, a versatile building block for luminescent materials

Energy Technology Data Exchange (ETDEWEB)

Milos, Mia [Departement de chimie physique, Universite de Geneve, 30 quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland); Hauser, Andreas, E-mail: andreas.hauser@unige.ch [Departement de chimie physique, Universite de Geneve, 30 quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland)

2013-01-15

Chromium(III)-trisoxalate, [Cr(ox){sub 3}]{sup 3-} (ox=C{sub 2}O{sub 4}{sup 2-}), incorporated into polymeric networks of composition [NaCr(ox){sub 3}][M{sup II}(bpy){sub 3}] and [NaCr(ox){sub 3}][M{sup III}(bpy){sub 3}]ClO{sub 4} (ox=C{sub 2}O{sub 4}{sup 2-}, bpy=2,2 Prime -bipyridine, M{sup II}=Zn, Fe, Ru; M{sup III}=Rh, Cr), results in interesting features ranging from phonon-assisted and resonant energy migration within the R{sub 1} line the {sup 2}E state to persistent spectral side-hole burning via the latter, and manifestations of specific nearest-neighbour {pi}-{pi} interactions between bipyridine and oxalate. - Highlights: Black-Right-Pointing-Pointer We present the multifaceted photophysical behaviour of chromium(III)-tris-oxalate. Black-Right-Pointing-Pointer We differentiate between phonon-assisted and resonant energy migration. Black-Right-Pointing-Pointer Resonant energy migration results in spectral diffusion. Black-Right-Pointing-Pointer Resonant energy transfer can be tuned via pressure dependant spectral overlap. Black-Right-Pointing-Pointer {pi}-{pi} interactions with the second coordination sphere create specific spectroscopic sites.

New heterocyclic derivatives of 2-amino-1,6-anhydro-2-deoxy-beta-D-glucopyranose containing 1,4-oxazepane or azepane ring

Czech Academy of Sciences Publication Activity Database

Trtek, T.; Černý, M.; Buděšínský, Miloš; Trnka, T.; Císařová, I.

2005-01-01

Roč. 70, č. 4 (2005), s. 466-478 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40550506 Keywords : carbohydrates * aminosugars * oxazepanes Subject RIV: CC - Organic Chemistry Impact factor: 0.949, year: 2005

The physiological effect of cobalt on watermelon cultivation

International Nuclear Information System (INIS)

Yao Naihua; Jin Yafang; Sun Yaochen; Huang Yiming

1993-01-01

Cobalt has essential physiological action on both animals and plants. For the latter it can raise plant's nitrogen-fixing ability and saccharine content. Spray of cobalt mixed with other nutritive elements can improve the germinatit of seeds and the yield of fruit. For specifying the nutritive function of cobalt upon watermelon, isotope 60 Co was mixed into a complex leaf nutritive aqua and the regularity of transferring and absorbing cobalt in the watermelon's body was investigated

Relaxation resistance of heat resisting alloys with cobalt

International Nuclear Information System (INIS)

Borzdyka, A.M.

1977-01-01

Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading

Two dimensionality in quasi-one-dimensional cobalt oxides confirmed by muon-spin spectroscopy

International Nuclear Information System (INIS)

Sugiyama, J.; Nozaki, H.; Ikedo, Y.; Mukai, K.; Andreica, D.; Amato, A.; Brewer, J.H.; Ansaldo, E.J.; Morris, G.D.; Takami, T.; Ikuta, H.

2007-01-01

The quasi-one-dimensional (Q1D) cobalt oxides, A n+2 Co n+1 O 3n+3 (A=Ca, Sr and Ba, n=1-∼), were investigated by muon-spin spectroscopy under applied pressures of up to 1.1GPa. The relationship between the onset Neel temperature T N on and the inter-chain distance (d ic ), which increases monotonically with n, is well fitted by the formula T N /T N,0 =(1-d ic /d ic,0 ) β . The T N on -d ic curve also predicts a large P dependence of T N for the compounds with n>=5, i.e., in the vicinity of d ic,0 , while the n=1-4 compounds show only a very small effect. Indeed, our high-pressure μ + SR results show that T N of BaCoO 3 (n=∼) is enhanced by P, with a slope of 2.1 K/GPa, whereas no detectable changes between ambient pressure and 1.0 GPa for both Ca 3 Co 2 O 6 (n=1) and Sr 4 Co 3 O 9 (n=2). This clearly confirms the role of the 2D-AF interaction on T N on in the Q1D cobalt oxides

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Mishra, A; Singh, M P; Singh, V K

1982-05-01

The nitrato-complexes, (Y(PyBzH)/sub 2/(NO/sub 3/)/sub 2/)NO/sub 3/.H/sub 2/O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole) are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm/sup -1/cm/sup 2/mol/sup -1/) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the positive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C/sub 2/v) and uncoordinated (D/sub 3/h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

International Nuclear Information System (INIS)

Mishra, A.; Singh, M.P.; Singh, V.K.

1982-01-01

The nitrato-complexes, [Y(PyBzH) 2 (NO 3 ) 2 ]NO 3 .H 2 O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole] are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm -1 cm 2 mol -1 ) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the terpositive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C 2 v) and uncoordinated (D 3 h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms. (author)

Preservasi Semen Kambing Peranakan Etawa dalam Pengencer Tris dan Sitrat Kuning Telur dengan Penambahan Sodium Dodecyl Sulphate (THE PRESERVATION OF ETTAWA GRADE BUCK SEMEN IN TRIS AND CITRATE EGG YOLK DILUENTS SUPPLEMENTED WITH SODIUM DODECYL SULPHATE

Directory of Open Access Journals (Sweden)

Nur Hidayati

2015-10-01

Full Text Available This study was conducted to determineSDS concentration also to compare Tris egg yolk and citrateegg yolk on the quality of ettawa grade chilled semen. The study consist of two experiments. The firstexperiment was to determine the best SDS concentration in Tris egg yolk diluents and the second experimentwas to compare the SDS suplementation in tris and citrate egg yolk in the quality of ettawa grade chilledsemen. The semen were collected from three bucks, immediately after collection the semen evalutedmacro and microscopycally. Semen demonstrate more than 70% motility and less than 10% spermatozoaabnormality, individually divided into four tube, each tube was diluted in egg yolk supplemented with 0;0,025; 0,05; and 0.075% SDS then stored at 5°C for 72 hours. The quality of chilled semen was observefor motility and viability every 12 hours. Result demonstrated that 0.05% SDS was the best concentrationcompared to others. In the second experiment,the semen were diluted in four different diluents, it wereTris egg yolk (TEY, Tris egg yolk with 0.05% SDS (TEYS, citrate egg yolk (CEY and citrate egg yolk with0.05% SDS (CEYS. Result demonstrated that the mean value of motility and viability of spermatozoa inTEYSdiluents (67.08 ± 6.43% and77.07 ± 6.78% was higher (p<0.05 than CEYS (60.42 ± 9.05% and72.31± 7.45%, TEY (59.23 ± 9.41% and71.21 ± 8.56% and CEY (53.45 ± 11.33% and67.74 ± 8.90%. In conclusion,supplementation of 0.05% SDS in TEY was maintained best sperm quality compared to other diluentsduring preservation.

Thermal Effect on Structure Organizations in Cobalt-Fullerene Nanocomposition

Czech Academy of Sciences Publication Activity Database

Lavrentiev, Vasyl; Vacík, Jiří; Naramoto, H.; Sakai, S.

2010-01-01

Roč. 10, č. 4 (2010), s. 2624-2629 ISSN 1533-4880 R&D Projects: GA AV ČR(CZ) KAN400480701; GA AV ČR IAA200480702; GA MŠk(CZ) LC06041 Institutional research plan: CEZ:AV0Z10480505 Keywords : cobalt * fullerene * simultaneous deposition Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.351, year: 2010

Synthesis and characterization of a Schiff base Cobalt (III) complex ...

African Journals Online (AJOL)

Schiff base molecule acts as tridentate ligand to form two five-membered chelate rings with the Co(III) ion. In the crystal structure three meridionally arranged nitrogen atoms from three azide ligands complete a distorted octahedral geometry around the metal center. The distortion from an ideal octahedron is evident from the ...

Study of high coercive force films made by vacuum deposition of cobalt onto chromium

International Nuclear Information System (INIS)

Randet, Denis

1969-01-01

A new method to make high coercive force films, by successive evaporations of chromium and cobalt, was demonstrated in 1966 at the 'Laboratoire d'Electronique et de Technologie de l'Informatique'. This work first contains a description of the magnetic properties of these films according to the conditions of preparation. These properties, which are isotropic in the plane of the film, are then related to the crystallographic structure of chromium and cobalt, in particular through electron microscopy. It is concluded that the coercive force is essentially due to the high magneto-crystalline anisotropy of cobalt in its hexagonal phase and depends, altogether with the shape of the hysteresis loop, on the magnetostatic coupling between the grains, which varies according to their dimensions. The chromium underlayer, if its surface is free enough of oxygen contamination, induces the growth of the hexagonal phase and influences the grain size of cobalt by a sort of epitaxy. At last, the behaviour of the Co/Cr films as a magnetic recording material is briefly examined and discussed. (author) [fr

Heating-induced inner-sphere substitution and reduction-oxidation reactions of the solid phenanthroline containing cobalt (2) and cobalt (3) complexes

International Nuclear Information System (INIS)

Palade, D.M.

1996-01-01

The results of the differential thermal and thermogravimetric analyses of solid phenanthroline-containing complexes of cobalt (2) and cobalt (3) in the atmosphere of the air have been analyzed. Mechanism of redox reactions occurring when cobalt (3) complexes are heated has been discussed. It is shown that some of gaseous products of the redox processes appear as a result of secondary reactions and not the processes of the ligands oxidation by Co 3+ . The influence of certain inner-sphere and coordinated anions (of I, inclusively) on cobalt (3) complexes behaviour during heating has been considered

Control of carbon nanotube growth using cobalt nanoparticles as catalyst

International Nuclear Information System (INIS)

Huh, Yoon; Green, Malcolm L.H.; Kim, Young Heon; Lee, Jeong Yong; Lee, Cheol Jin

2005-01-01

We have controllably grown carbon nanotubes using uniformly distributed cobalt nanoparticles as catalyst. Cobalt nanoparticles with a uniform size were synthesized by chemical reaction and colloidal solutions including the cobalt nanoparticles were prepared. The cobalt nanoparticles were uniformly distributed on silicon substrates by a spin-coating method. Carbon nanotubes with a uniform diameter were synthesized on the cobalt nanoparticles by thermal chemical vapor deposition of acetylene gas. The density and vertical alignment of carbon nanotubes could be controlled by adjusting the density of cobalt (Co) nanoparticles

A 3D POLYHEDRAL METAL–ORGANIC FRAMEWORK AS DRUG ...

African Journals Online (AJOL)

Research and Development of New Medical Materials of Guangdong .... funded project of Guangdong Medical University (Z2016001 and M2016023), Innovative ... thermodynamic studies of five coodrdinate cobalt(III) Schiff base complexes.

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

Directory of Open Access Journals (Sweden)

Carmen Mejuto

2015-12-01

Full Text Available The coordination versatility of a 1,3,5-triphenylbenzene-tris-mesoionic carbene ligand is illustrated by the preparation of complexes with three different metals: rhodium, iridium and nickel. The rhodium and iridium complexes contained the [MCl(COD] fragments, while the nickel compound contained [NiCpCl]. The preparation of the tris-MIC (MIC = mesoionic carbene complex with three [IrCl(CO2] fragments, allowed the estimation of the Tolman electronic parameter (TEP for the ligand, which was compared with the TEP value for a related 1,3,5-triphenylbenzene-tris-NHC ligand. The electronic properties of the tris-MIC ligand were studied by cyclic voltammetry measurements. In all cases, the tris-MIC ligand showed a stronger electron-donating character than the corresponding NHC-based ligands. The catalytic activity of the tri-rhodium complex was tested in the addition reaction of arylboronic acids to α,β-unsaturated ketones.

Dosing of anaerobic granular sludge bioreactors with cobalt: Impact of cobalt retention on methanogenic activity

KAUST Repository

Fermoso, Fernando G.

2010-12-01

The effect of dosing a metal limited anaerobic sludge blanket (UASB) reactor with a metal pulse on the methanogenic activity of granular sludge has thus far not been successfully modeled. The prediction of this effect is crucial in order to optimize the strategy for metal dosage and to prevent unnecessary losses of resources. This paper describes the relation between the initial immobilization of cobalt in anaerobic granular sludge cobalt dosage into the reactor and the evolution of methanogenic activity during the subsequent weeks. An operationally defined parameter (A0· B0) was found to combine the amount of cobalt immobilized instantaneously upon the pulse (B0) and the amount of cobalt immobilized within the subsequent 24. h (A0). In contrast with the individual parameters A0 and B0, the parameter A0· B0 correlated significantly with the methanogenic activity of the sludge during the subsequent 16 or 35. days. This correlation between metal retention and activity evolution is a useful tool to implement trace metal dosing strategies for biofilm-based biotechnological processes. © 2010.

Tris(O-cyclo­hexyl dithio­carbonato-κS)anti­mony(III)

Science.gov (United States)

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2009-01-01

In the mol­ecule of the title compound, [Sb(C7H11OS2)3], the anti­mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination. PMID:21581504

Spectrographic analysis of uranium-based alloys; Analyse spectrographique d'alliages a base d'uranium

Energy Technology Data Exchange (ETDEWEB)

Baudin, G.; Blum, P.

1959-07-01

The authors describe a spectrographic method for dosing cobalt in cobalt-uranium alloys with cobalt content from 0.05 to 10 per cent. They describe sample preparation, alloy solution, spectrographic conditions, and photometry operations. In a second part, they address the dosing of boron in uranium borides. They implement the so-called 'porous cup' method. Boride is dissolved by fusion with Co{sub 3}-NaK [French] Uranium-Cobalt: il est decrit une methode spectrographique de dosage de cobalt dans des alliages cobalt-uranium pour des teneurs de 0,05 pour cent a 10 pour cent de Co. On opere sur solution avec le fer comme standard interne. Borure d'Uranium: ici encore on opere par la methode dite 'porous cup', le fer etant conserve comme standard interne. Le borure est mis en solution par fusion avec Co{sub 3}NaK. (auteurs)

75 FR 35807 - 2-(Hydroxymethyl)-2-nitro-1,3-propanediol (Tris Nitro); Notice of Receipt of Request to...

Science.gov (United States)

2010-06-23

... website is an ``anonymous access'' system, which means EPA will not know your identity or contact... Premises. 464-658 Tris Nitro\\TM\\ Brand of The Dow Chemical Use in metalworking 50% (Aqueous) For Company...; Livestock and poultry premises. 464-663 Tris Nitro\\TM\\ Brand of The Dow Chemical Use in paints, 50% Aqueous...

Cobalt-60 control in Ontario Hydro reactors

International Nuclear Information System (INIS)

Lacy, C.S.

1988-01-01

This paper discusses the impact of specifying reduced Cobalt-59 in the primary heat transport circuit materials of construction on the radiation fields developed around the primary circuit. An eight-fold reduction in steam generator radiation fields due to Cobalt-60 has been observed for two identical sets of reactors, one with and one without Cobalt-59 control. The comparison is between eight reactors at the Pickering Nuclear Generating Station (PNGS). Units 5 to 8 (PNGS-B) are identical to Units 1 to 4 (PNGS-A) except that PNGS-B has reduced impurity Cobalt-59 in the alloys of construction and a reduced use of stellite. The effects of chemistry control are also discussed

Investigation of iron(III) reduction and trace metal interferences in the determination of dissolved iron in seawater using flow injection with luminol chemiluminescence detection

Energy Technology Data Exchange (ETDEWEB)

Ussher, Simon J. [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Milne, Angela [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Landing, William M. [Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Attiq-ur-Rehman, Kakar [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Seguret, Marie J.M.; Holland, Toby [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Achterberg, Eric P. [National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH (United Kingdom); Nabi, Abdul [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Worsfold, Paul J., E-mail: pworsfold@plymouth.ac.uk [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

2009-10-12

A detailed investigation into the performance of two flow injection-chemiluminescence (FI-CL) manifolds (with and without a preconcentration column) for the determination of sub-nanomolar dissolved iron (Fe(II) + Fe(III)), following the reduction of Fe(III) by sulphite, in seawater is described. Kinetic experiments were conducted to examine the efficiency of reduction of inorganic Fe(III) with sulphite under different conditions and a rigorous study of the potential interference caused by other transition metals present in seawater was conducted. Using 100 {mu}M concentrations of sulphite a reduction time of 4 h was sufficient to quantitatively reduce Fe(III) in seawater. Under optimal conditions, cobalt(II) and vanadium(IV)/(III) were the major positive interferences and strategies for their removal are reported. Specifically, cobalt(II) was masked by the addition of dimethylglyoxime to the luminol solution and vanadium(IV) was removed by passing the sample through an 8-hydroxyquinoline column in a low pH carrier stream. Manganese(II) also interfered by suppression of the CL response but this was not significant at typical open ocean concentrations.

An elevator for cobalt-60 source

International Nuclear Information System (INIS)

Tang Zaimin; Liang Donghu

1990-07-01

The elevator used for cobalt-60 source is a key device in the irradiation industry. It plays an important role in the safety and control of irradiation operation as well as the utilization rate of radiation source. From 1983 to 1986, Beijing Institute of Nuclear Engineering undertook designing of various size irradiation projects for different uses. Since then a kind of cobalt-60 source elevator suited for the irradiator of wet-source-storage has been chosen. It is reliable in the operation and complete in the function. An automatic control circuit brings the systems of cobalt-60 source elevator into an interlock system which ensures the irradiation operation safety. Besides introducing the structural features and performance of this elevator, the conditions of safety interlocking in raising or lowering the cobalt-60 source is also discussed. The discussion is from the safety viewpoint of operating an irradiator and irradiation technology

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Science.gov (United States)

2010-04-01

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

Dispersible cobalt chromite nanoparticles: facile synthesis and size driven collapse of magnetism

Czech Academy of Sciences Publication Activity Database

Zákutná, D.; Matulková, I.; Kentzinger, E.; Medlín, R.; Su, Y.; Nemkovski, K.; Disch, S.; Vejpravová, Jana; Nižňanský, D.

2016-01-01

Roč. 6, č. 109 (2016), s. 107659-107668 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : cobalt chromite * nanoparticle * multiferoic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.108, year: 2016

Mössbauer effect studies and X-ray diffraction analysis of cobalt ...

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 26; Issue 5. Mössbauer effect studies and X-ray diffraction analysis of cobalt ferrite prepared in powder form by thermal decomposition method. M D Joseph Sebastian B Rudraswamy M C Radhakrishna Ramani. Magnetic Materials Volume 26 Issue 5 August 2003 pp ...

Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

DEFF Research Database (Denmark)

Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil

2010-01-01

Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure.......Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure....

The role of cobalt on the creep of Waspaloy

Science.gov (United States)

Jarrett, R. N.; Chin, L.; Tien, J. K.

1984-01-01

Cobalt was systematically replaced with nickel in Waspaloy (which normally contains 13% Co) to determine the effects of cobalt on the creep behavior of this alloy. Effects of cobalt were found to be minimal on tensile strengths and microstructure. The creep resistance and the stress rupture resistance determined in the range from 704 to 760 C (1300 to 1400 C) were found to decrease as cobalt was removed from the standard alloy at all stresses and temperatures. Roughly a ten-fold drop in rupture life and a corresponding increase in minimum creep rate were found under all test conditions. Both the apparent creep activation energy and the matrix contribution to creep resistance were found to increase with cobalt. These creep effects are attributed to cobalt lowering the stacking fault energy of the alloy matrix. The creep resistance loss due to the removal of cobalt is shown to be restored by slightly increasing the gamma' volume fraction. Results are compared to a previous study on Udimet 700, a higher strength, higher gamma' volume fraction alloy with similar phase chemistry, in which cobalt did not affect creep resistance. An explanation for this difference in behavior based on interparticle spacing and cross-slip is presented.

Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

Science.gov (United States)

Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

2017-08-01

This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

Science.gov (United States)

Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

2016-02-01

An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Stability of tris-1,10-phenanthroline iron (II) complex in biomineral particles produced by Klebsiella oxytoca

International Nuclear Information System (INIS)

Anghel, L.V.; Balasoiu, M.; Lazar, D.M.; Ishchenko, L.A.

2011-01-01

The composition of composites has a huge impact on the stability of tris-1,10-phenanthroline iron (II) complex during the determination of total iron content. The subject of this work is the determination of the stability of tris-1,10-phenanthroline iron (II) complex in samples of biominerals produced by bacteria Klebsiella oxytoca. The stability of this complex was monitored in the time period of 0-60 min. The aim of this work is to determine the concentration of the biogenic ferrihydrite in the samples and the time interval in which the absorbance of the complex is highest. The UV-Vis spectrophotometric method was used for the determination. Obtained results indicate that for more exact estimations of the concentration of biogenic ferrihydrite, absorbance of tris-1,10-phenanthroline iron (II) complex should be measured within 25 min from the moment ortho-phenanthroline was added

COBALT COMPOUNDS AS ANTIDOTES FOR HYDROCYANIC ACID.

Science.gov (United States)

EVANS, C L

1964-12-01

The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5xLD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5xLD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3xLD50) than for mice (2xLD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered.

The Spectrum and Term Analysis of Co III Measured Using Fourier Transform and Grating Spectroscopy

Science.gov (United States)

Smillie, D. G.; Pickering, J. C.; Nave, G.; Smith, P. L.

2016-03-01

The spectrum of Co III has been recorded in the region 1562-2564 Å (64,000 cm-1-39,000 cm-1) by Fourier transform (FT) spectroscopy, and in the region 1317-2500 Å (164,000 cm-1-40,000 cm-1) using a 10.7 m grating spectrograph with phosphor image plate detectors. The spectrum was excited in a cobalt-neon Penning discharge lamp. We classified 514 Co III lines measured using FT spectroscopy, the strongest having wavenumber uncertainties approaching 0.004 cm-1 (approximately 0.2 mÅ at 2000 Å, or 1 part in 107), and 240 lines measured with grating spectroscopy with uncertainties between 5 and 10 mÅ. The wavelength calibration of 790 lines of Raassen & Ortí Ortin and 87 lines from Shenstone has been revised and combined with our measurements to optimize the values of all but one of the 288 previously reported energy levels. Order of magnitude reductions in uncertainty for almost two-thirds of the 3d64s and almost half of the 3d64p revised energy levels are obtained. Ritz wavelengths have been calculated for an additional 100 forbidden lines. Eigenvector percentage compositions for the energy levels and predicted oscillator strengths have been calculated using the Cowan code.

Characterization of a Porous Carbon Material Functionalized with Cobalt-Oxide/Cobalt Core-Shell Nanoparticles for Lithium Ion Battery Electrodes

KAUST Repository

Anjum, Dalaver H.; Rasul, Shahid; Roldan-Gutierrez, Manuel A.; Da Costa, Pedro M. F. J.

2016-01-01

A nanoporous carbon (C) material, functionalized with Cobalt-Oxide/Cobalt (CoO/Co) core-shell nanoparticles (NPs), was structurally and chemically characterized with transmission electron microcopy (TEM) while its electrochemical response

Cobalt mineral exploration and supply from 1995 through 2013

Science.gov (United States)

Wilburn, David R.

2011-01-01

The global mining industry has invested a large amount of capital in mineral exploration and development over the past 15 years in an effort to ensure that sufficient resources are available to meet future increases in demand for minerals. Exploration data have been used to identify specific sites where this investment has led to a significant contribution in global mineral supply of cobalt or where a significant increase in cobalt production capacity is anticipated in the next 5 years. This report provides an overview of the cobalt industry, factors affecting mineral supply, and circumstances surrounding the development, or lack thereof, of key mineral properties with the potential to affect mineral supply. Of the 48 sites with an effective production capacity of at least 1,000 metric tons per year of cobalt considered for this study, 3 producing sites underwent significant expansion during the study period, 10 exploration sites commenced production from 1995 through 2008, and 16 sites were expected to begin production by 2013 if planned development schedules are met. Cobalt supply is influenced by economic, environmental, political, and technological factors affecting exploration for and production of copper, nickel, and other metals as well as factors affecting the cobalt industry. Cobalt-rich nickel laterite deposits were discovered and developed in Australia and the South Pacific and improvements in laterite processing technology took place during the 1990s and early in the first decade of the 21st century when mining of copper-cobalt deposits in Congo (Kinshasa) was restricted because of regional conflict and lack of investment in that country's mining sector. There was also increased exploration for and greater importance placed on cobalt as a byproduct of nickel mining in Australia and Canada. The emergence of China as a major refined cobalt producer and consumer since 2007 has changed the pattern of demand for cobalt, particularly from Africa and

Luminescent sensing of organophosphates using europium(III) containing imprinted polymers prepared by RAFT polymerization

International Nuclear Information System (INIS)

Southard, Glen E.; Van Houten, Kelly A.; Ott, Edward W.; Murray, George M.

2007-01-01

Molecularly imprinted polymers capable of sensing organophosphorous compounds by luminescence have been prepared by reversible addition fragmentation chain transfer (RAFT) polymerization. The polymer contained a dithiobenzoate substituted tris(β-diketonate) europium(III) complex which served as a polymerization substrate and as a luminescent binding site for pinacolyl methylphosphonate (PMP), the hydrolysis product of the nerve agent Soman. The resultant polymer allowed quantitation of PMP in the low ppb range with minimal interference from similar compounds. Polymers were characterized by luminescence spectroscopy and scanning electron microscopy

Optical transitions and electronic interactions in self-assembled cobalt-fullerene mixture films

Czech Academy of Sciences Publication Activity Database

Lavrentiev, Vasyl; Chvostová, Dagmar; Lavrentieva, Inna; Vacík, Jiří; Daskal, Y.; Barchuk, M.; Rafaja, D.; Dejneka, Alexandr

2017-01-01

Roč. 50, č. 48 (2017), č. článku 485305. ISSN 0022-3727 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015088; GA MŠk LM2015056 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : fullerene * cobalt * electronic interaction * optical absorption * mixture film Subject RIV: BM - Solid Matter Physics ; Magnetism; BO - Biophysics (FZU-D) OBOR OECD: Condensed matter physics (including formerly solid state physics , supercond.); Biophysics (FZU-D) Impact factor: 2.588, year: 2016

The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

Energy Technology Data Exchange (ETDEWEB)

Smith, Leah J.; Holmes, Amie L. [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Kandpal, Sanjeev Kumar; Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, ME (United States); Zheng, Tongzhang [Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT (United States); Wise, John Pierce, E-mail: John.Wise@usm.maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States)

2014-08-01

Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

Thermal stabilities of electromechanical properties in cobalt-modified strontium bismuth titanate (SrBi{sub 4}Ti{sub 4}O{sub 15})

Energy Technology Data Exchange (ETDEWEB)

Wang, Qian; Cao, Zhao-Peng; Wang, Chun-Ming, E-mail: wangcm@sdu.edu.cn; Fu, Qing-Wei; Yin, De-Fu; Tian, Hu-He

2016-07-25

Bismuth layer-structured ferroelectric (BLSF) strontium bismuth titanate (SrBi{sub 4}Ti{sub 4}O{sub 15}, SBT) ceramic oxides with B-site cobalt substitutions have been synthesized using conventional solid–state reaction. The dielectric, piezoelectric, and ferroelectric properties of cobalt-modified SBT are investigated in detail. The results indicate that cobalt is very effective in promoting the piezoelectric performance of SBT. The SBT modified with 3 mol% Co{sup 3+} (SBT-3Co) exhibits the optimized piezoelectric properties, with a piezoelectric constant d{sub 33} of 28 pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance, resonance frequencies, and electromechanical coupling factors (k{sub p} and k{sub t}) reveal that the cobalt-modified SBT ceramics have good thermal stabilities of electromechanical properties up to 300 °C. These results demonstrate that the cobalt-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications. - Graphical abstract: The manuscript deals with the thermal stabilities of piezoelectric properties of cobalt-modified SrBi{sub 4}Ti{sub 4}O{sub 15} (SBT) ceramics. The 3 mol% Co{sup 3+} modified SBT (SBT-3Co) ceramics exhibit a piezoelectric constant d{sub 33} of 28 pC/N and a Curie temperature T{sub c} of 528 °C. The SBT-3Co ceramics have good thermal stabilities of electromechanical properties up to 300 °C. - Highlights: • A high level of piezoelectric performance (d{sub 33}∼28 pC/N)is obtained. • High Curie temperature (T{sub c}∼528 °C) is acquired for the optimal composition. • The SBT-3Co exhibits good thermal stabilities of electromechanical properties. • The Co-modified SrBi{sub 4}Ti{sub 4}O{sub 15} is promising as high temperature piezoelectric material.

Tris(N,N,N′,N′,N′′,N′′-hexaethylguanidinium dodecaiodidotribismuthate(III

Directory of Open Access Journals (Sweden)

Ioannis Tiritiris

2016-03-01

Full Text Available The asymmetric unit of title compound, (C13H30N33[Bi3I12], comprises one cation and two independent (1/6 fragments of the [Bi3I12]3− ions. The C—N bond lengths in the guanidinium ion range from 1.340 (4 to 1.345 (4 Å, indicating partial double-bond character pointing towards charge delocalization within the NCN planes. The BiIII ions are distorted octahedrally coordinated by six iodide ions, with Bi—I bond lengths ranging from 2.9206 (3 to 3.3507 (3 Å. Three [BiI6]3− octahedra are fused together through face-sharing, forming a trinuclear [Bi3I12]3− unit.

Hydrometallurgical process for the recovery of high value metals from spent lithium nickel cobalt aluminum oxide based lithium-ion batteries

Science.gov (United States)

Joulié, M.; Laucournet, R.; Billy, E.

2014-02-01

A hydrometallurgical process is developed to recover valuable metals of the lithium nickel cobalt aluminum oxide (NCA) cathodes from spent lithium-ion batteries (LIBs). Effect of parameters such as type of acid (H2SO4, HNO3 and HCl), acid concentration (1-4 mol L-1), leaching time (3-18 h) and leaching temperature (25-90 °C) with a solid to liquid ratio fixed at 5% (w/v) are investigated to determine the most efficient conditions of dissolution. The preliminary results indicate that HCl provides higher leaching efficiency. In optimum conditions, a complete dissolution is performed for Li, Ni, Co and Al. In the nickel and cobalt recovery process, at first the Co(II) in the leaching liquor is selectively oxidized in Co(III) with NaClO reagent to recover Co2O3, 3H2O by a selective precipitation at pH = 3. Then, the nickel hydroxide is precipitated by a base addition at pH = 11. The recovery efficiency of cobalt and nickel are respectively 100% and 99.99%.

Total body irradiation with a reconditioned cobalt teletherapy unit.

Science.gov (United States)

Evans, Michael D C; Larouche, Renée-Xavière; Olivares, Marina; Léger, Pierre; Larkin, Joe; Freeman, Carolyn R; Podgorsak, Ervin B

2006-01-01

While the current trend in radiotherapy is to replace cobalt teletherapy units with more versatile and technologically advanced linear accelerators, there remain some useful applications for older cobalt units. The expansion of our radiotherapy department involved the decommissioning of an isocentric cobalt teletherapy unit and the replacement of a column-mounted 4-MV LINAC that has been used for total body irradiation (TBI). To continue offering TBI treatments, we converted the decommissioned cobalt unit into a dedicated fixed-field total body irradiator and installed it in an existing medium-energy LINAC bunker. This article describes the logistical and dosimetric aspects of bringing a reconditioned cobalt teletherapy unit into clinical service as a total body irradiator.

Supramolecular tetracluster-cobalt porphyrin: a four-electron transfer catalyst for dioxygen reduction

International Nuclear Information System (INIS)

Winnischofer, Herbert; Otake, Vesper Yoshiyuki; Dovidauskas, Sergio; Nakamura, Marcelo; Toma, Henrique Eisi; Araki, Koiti

2004-01-01

Electrocatalysis by CoTCP {CoTCP meso-tetrakis(4-pyridyl)porphynatocobalt(III)} coordinated to four [Ru 3 (μ 3 -O)(μ 2 -CH 3 CO 2 ) 6 (py) 2 ] + complexes in the four-electron reduction of dioxygen, has been unequivocally demonstrated in this work by using two types of electrostatically assembled films of CoTCP and anionic zinc or free-base meso-tetrakis(4-sulfonatophenyl)porphyrins (ZnTPPS or H 2 TPPS), as well as, by employing different electrode materials. An enhanced electrocatalytic activity has been observed, in spite of the fact that the typical bis-coordination of dioxygen to two cobalt porphyrin sites is precluded in such CoTCP/ZnTPPS or CoTCP/H 2 TPPS bilayered films. In addition, negligible ring currents have been observed in ring-disk voltammetry measurements, yielding straight Levich and Koutecky-Levich plots, whose slopes approached the theoretical 4e - curve in air, or in O 2 saturated solutions (pH 3-5). The use of gold instead of glassy carbon (GC) electrodes has not also significantly perturbed the mechanism. By ruling out any influence from the electrode materials, a well known critical point in the catalysis by cobalt porphyrins, the results have shown that CoTCP is acting as a four-electron transfer catalyst for dioxygen reduction. Also, by excluding the possibility of bis-coordination of dioxygen, it was shown that the electronic and supramolecular effects exerted by the peripheral ruthenium cluster complexes should be triggering the four-electron catalytic activity of the cobalt porphyrin center

Interaction of HEPES buffer with glass-ceramic scaffold: Can HEPES replace TRIS in SBF?

Science.gov (United States)

Rohanová, Dana; Horkavcová, Diana; Paidere, Laine; Boccaccini, Aldo Roberto; Bozděchová, Pavlína; Bezdička, Petr

2018-01-01

An international standard (ISO: 23317:2014) exists for the in vitro testing of inorganic biomaterials in simulated body fluid (SBF). This standard uses TRIS buffer to maintain neutral pH in SBF, but in our previous paper, we showed that the interaction of a tested glass-ceramic material with TRIS can produce false-positive results. In this study, we evaluated whether the HEPES buffer, which also belongs to the group of Good´s buffers, would be more suitable for SBF. We compared its suitability in two media: SBF with HEPES and demineralized water with HEPES. The tested scaffold (45S5 bioactive glass-based) was exposed to the media under a static-dynamic arrangement (solutions were replaced on a daily basis) for 15 days. Leachate samples were collected daily for the analysis of Ca 2+ ions and Si (AAS), (PO 4 ) 3- ions (UV-VIS), and to measure pH. The glass-ceramic scaffold was analyzed by SEM/EDS, XRD, and WD-XRF before and after 0.3, 1, 3, 7, 11, and 15 days of exposure. Our results confirmed the rapid selective dissolution of the glass-ceramic crystalline phase (Combeite) containing Ca 2+ ions due to the presence of HEPES, hydroxyapatite supersaturation being reached within 24 h in both solutions. These new results suggest that, like TRIS, HEPES buffer is not suitable for the in vitro testing of highly reactive inorganic biomaterials (glass, glass-ceramics). The ISO standard for such tests requires revision, but HEPES is not a viable alternative to TRIS buffer. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 143-152, 2018. © 2016 Wiley Periodicals, Inc.

Potential for cobalt recovery from lateritic ores in Europe

Science.gov (United States)

Herrington, R.

2012-04-01

Cobalt is one of the 'critical metals' identified under the EU Raw Materials Initiative. Annually the global mine production of cobalt is around 55,000 tonnes,with Europe's industries consuming around 30% of that figure. Currently Europe produces around 27 tonnes of cobalt from mines in Finland although new capacity is planned. Co-bearing nickel laterite ores being mined in Greece, Macedonia and Kosovo where the cobalt is currently not being recovered (ores have typical analyses of 0.055% Co and >1% Ni,). These ores are currently treated directly in pyrometallurgical plants to recover the contained nickel and this process means there is no separate cobalt product produced. Hydrometallurgical treatment of mineralogically suitable laterite ores can recover the cobalt; for example Cuba recovers 3,500 tonnes of cobalt from its laterite mining operations, which are of a similar scale to the current European operations. Implementation of hydrometallurgical techniques is in its infancy in Europe with one deposit in Turkey planning to use atmospheric heap leaching to recover nickel and copper from oxide-dominated ores. More widespread implementation of these methods to mineralogically suitable ore types could unlock the highly significant undeveloped resources (with metal contents >0.04% Co and >1% Ni), which have been defined throughout the Balkans eastwards into Turkey. At a conservative estimate, this region has the potential to supply up to 30% of the EU cobalt requirements.

Effect of Cobalt Sorption on Metal Fractionation in Anaerobic Granular Sludge

NARCIS (Netherlands)

Osuna, M.B.; Hullebusch, van E.D.; Zandvoort, M.H.; Iza, J.M.; Lens, P.N.L.

2004-01-01

A sequential extraction procedure was applied to two anaerobic methanogenic sludges (Eerbeek and Nedalco) to examine the speciation of micro- and macronutrients in the sludges after cobalt sorption by exposing the sludge to a 1 mM Co solution for 4 d at pH 7 and 30degreesC. The effect of different

In vitro antimicrobial activity of a commercial ear antiseptic containing chlorhexidine and Tris-EDTA.

Science.gov (United States)

Guardabassi, Luca; Ghibaudo, Giovanni; Damborg, Peter

2010-06-01

Minimum bactericidal concentrations (MBCs) of a commercial ear antiseptic containing chlorhexidine 0.15% and Tris-EDTA (Otodine) were determined by broth microdilution for 150 isolates representing the most common pathogens associated with canine otitis. The microorganisms were classified into three groups according to their levels of susceptibility. The most susceptible group included Staphylococcus pseudintermedius, Malassezia pachydermatis, Streptococcus canis and Corynebacterium auriscanis, which were generally killed by 1 : 64 dilution of the antiseptic product (MBC = 23/0.8 microg/mL of chlorhexidine/Tris-EDTA). The most resistant organism was Proteus mirabilis, which survived up to 1 : 8 dilution of the product (MBC = 375/12 microg/mL). Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus displayed intermediate MBCs ranging between 188/6 and 47/1.5 microg/mL. Interestingly, S. pseudintermedius was more susceptible than S. aureus, and no significant difference was observed between meticillin-resistant and meticillin-susceptible isolates within each species, indicating that antiseptic use is unlikely to co-select for meticillin resistance. Although the concentrations required for killing (MBCs) varied considerably with microorganism type, the combination of chlorhexidine 0.15% and Tris-EDTA was active against all the pathogens most commonly involved in canine otitis.

Effects of tris-based pumpkin seed milk extender supplemented with ...

African Journals Online (AJOL)

The effects of Tris based pumpkin seed milk extender supplemented with Vitamin C on sperm viability after storage was carried out in an in vitro study. Semen samples obtained from five (5) intact West African Dwarf (WAD) WAD bucks were pooled together for this study. The pooled semen were divided into 5 equal aliquots ...

The significant role of covalency in determining the ground state of cobalt phthalocyanines molecule

Directory of Open Access Journals (Sweden)

Jing Zhou

2016-03-01

Full Text Available To shed some light on the metal 3d ground state configuration of cobalt phthalocyanines system, so far in debate, we present an investigation by X-ray absorption spectroscopy (XAS at Co L2,3 edge and theoretical calculation. The density functional theory calculations reveal highly anisotropic covalent bond between central cobalt ion and nitrogen ligands, with the dominant σ donor accompanied by weak π-back acceptor interaction. Our combined experimental and theoretical study on the Co-L2,3 XAS spectra demonstrate a robust ground state of 2A1g symmetry that is built from 73% 3d7 character and 27% 3 d 8 L ¯ ( L ¯ denotes a ligand hole components, as the first excited-state with 2Eg symmetry lies about 158 meV higher in energy. The effect of anisotropic and isotropic covalency on the ground state was also calculated and the results indicate that the ground state with 2A1g symmetry is robust in a large range of anisotropic covalent strength while a transition of ground state from 2A1g to 2Eg configuration when isotropic covalent strength increases to a certain extent. Here, we address a significant anisotropic covalent effect of short Co(II-N bond on the ground state and suggest that it should be taken into account in determining the ground state of analogous cobalt complexes.

The effect of zirconium on cobalt catalyst in fischer-tropsch synthesis

International Nuclear Information System (INIS)

Moradi, GH.R.; Mahbob Basir, M.; Taeb, A.

2003-01-01

A series of 10 wt % Co/SiO 2 catalysts with different loading ratios of zirconia (0, 5, 10, 15, 20) has been prepared through an original pseudo sol-gel method. All catalysts were characterized by BET, XRD, SEM, and TPR experiments. The catalytic performance of the catalysts for the so-called fischer- tropsch synthesis was examined under H 2 /CO=2 at 230 d ig C and 8 bar in a fixed bed microreactor. By increasing zirconia, the Co-SiO 2 interaction decreases and is replaced by Co-Zr interaction which favours reduction of the catalyst at lower temperatures. While it leads to a higher degree of reduction and as increase in the metallic cobalt atoms on the surface. The activity of the promoted catalysts increases with the addition of zirconia (max. by a factor 2.5). The C 1 0 + selectivity increased with the addition of zirconia (from 42.3% in unpromoted catalyst to 68.8 % in the 20 % ZrO 2 promoted. This can be attributed to the higher amount of the surface Cobalt metal present and to the larger Cobalt particle size

Optimizing the relaxivity of GdIII complexes appended to InP/ZnS quantum dots by linker tuning.

Science.gov (United States)

Stasiuk, Graeme J; Tamang, Sudarsan; Imbert, Daniel; Gateau, Christelle; Reiss, Peter; Fries, Pascal; Mazzanti, Marinella

2013-06-21

Three bimodal MRI/optical nanosized contrast agents with high per-nanoparticle relaxivity (up to 2523 mM(-1) s(-1) at 35 MHz and 932 mM(-1) s(-1) at 200 MHz) have been prepared connecting up to 115 tris-aqua Gd(III) complexes to fluorescent non-toxic InP/ZnS quantum dots. The structure of the linker has an important effect on the relaxivity of the final multimeric contrast agent.

Tris(2,2'-bipyridyl) ruthenium(II)-bisoprolol-based electrochemiluminescence coupled with capillary zone electrophoresis

Energy Technology Data Exchange (ETDEWEB)

Wang Jingwu [Department of Chemistry, Nanchang University, Nanchang 330031 (China)], E-mail: wangjingwu@ncu.edu.cn; Zhang Xiaojun; Pi Fangfang [Department of Chemistry, Nanchang University, Nanchang 330031 (China); Wang Xiaoxia [Graduate School of Engineering, University of Fukui, Fukui 910-8507 (Japan); Yang Nianjun [Diamond Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 2-13, 1-1-1 Umezono, Tsukuba 305-8568 (Japan)], E-mail: nianjun.yang@iaf.fraunhofer.de

2009-03-01

Capillary zone electrophoresis (CZE) coupled with tris(2,2'-bipyridyl) ruthenium(II)-based end-column electrogenerated chemiluminescence (ECL) has been utilized to detect bisoprolol in drugs and tablets after its separation from metoprolol. Tetrahydrofuran was used as an additive in the running buffer to obtain the absolute ECL peak of bisoprolol. Bisoprolol reacts as a co-reactant in tris(2,2'-bipyridyl) ruthenium(II) ECL system. Under the optimized experimental conditions, bisoprolol was separated successfully and efficiently from metoprolol and other co-existed materials in tablets and urine samples. The ECL intensity of tris(2,2'-bipyridyl) ruthenium(II)-bisoprolol-based system is linear with the concentration of bisoprolol from 1.5 {mu}M to 0.3 mM with a detection limit of 0.3 {mu}M. Relative standard derivations of the ECL intensity are 2.58% for the detection of 15 {mu}M bisoprolol. This method is a simple, rapid, selective, and sensitive. It was applied successfully for the monitoring of bisoprolol in market available tablets and human urine samples.

Separation of Am(III) from Eu(III) by mixtures of triazynylbipyridine and bis(dicarbollide) extractants. The composition of the metal complexes extracted

International Nuclear Information System (INIS)

Narbutt, J.; Krejzler, J.

2006-01-01

Separation of trivalent actinides, in particular americium and curium, from lanthanides is an important step in an advanced partitioning process for future reprocessing of spent nuclear fuels. The use of soft donor (N and S) ligands makes it possible to separate the two groups of elements, probably because of the more covalent character in the complexes with actinides compared to the lanthanides. The aim of present work was to study solvent extraction of Am(III) and Eu(III) in a similar system with diethylhemi-BTP and COSAN: protonated bis(chlorodicarbollido)cobalt(III) or commo-3,3-cobalta-bis(8,9,12-trichlora-1,2-dicarbaclosododecaborane)ic acid. The present research was focused on both the determination of conditions for the separation of 241 Am(III) from 152 Eu in aqueous nitrate solution by using a synergistic extraction system and on the modelling of the process by slope analysis. Obtained values of the separation factors supported by the computer modelling permitted drawing the conclusions on the mechanism of the process and on the structure of extracted species

Time-resolved pump and probe x-ray absorption fine structure spectroscopy at beamline P11 at PETRA III

Energy Technology Data Exchange (ETDEWEB)

Göries, D., E-mail: dennis.goeries@desy.de; Roedig, P.; Stübe, N.; Meyer, J.; Warmer, M.; Weckert, E.; Meents, A., E-mail: alke.meents@desy.de [DESY Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Dicke, B.; Naumova, M.; Rübhausen, M. [Center for Free-Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg (Germany); Galler, A.; Gawelda, W.; Geßler, P.; Sotoudi Namin, H.; Beckmann, A. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); Britz, A.; Bressler, C. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Schlie, M. [Institut für Experimentalphysik, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

2016-05-15

We report about the development and implementation of a new setup for time-resolved X-ray absorption fine structure spectroscopy at beamline P11 utilizing the outstanding source properties of the low-emittance PETRA III synchrotron storage ring in Hamburg. Using a high intensity micrometer-sized X-ray beam in combination with two positional feedback systems, measurements were performed on the transition metal complex fac-Tris[2-phenylpyridinato-C2,N]iridium(III) also referred to as fac-Ir(ppy){sub 3}. This compound is a representative of the phosphorescent iridium(III) complexes, which play an important role in organic light emitting diode (OLED) technology. The experiment could directly prove the anticipated photoinduced charge transfer reaction. Our results further reveal that the temporal resolution of the experiment is limited by the PETRA III X-ray bunch length of ∼103 ps full width at half maximum (FWHM).

Contribution to the study of the oxidation of cobalt and its protoxide in air at high temperatures; Contribution a l'etude de l'oxydation du cobalt et de son protoxyde dans l'air aux temperatures elevees

Energy Technology Data Exchange (ETDEWEB)

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

1964-01-15

The surface oxidation process of cobalt in air follows, a parabolic law and is characterized between 750 and 1350 deg. C by an activation energy of 41,000 cals/mole. Between 400 and 900 deg. C the oxide film is made up of two layers: CoO next to the metal and Co{sub 3}O{sub 4} on the surface. Above 900 deg. C only CoO remains. The morphological properties of these films have been studied; growth anisotropy, crystallization facies, oxide grain growth, texture, nucleation of Co{sub 3}O{sub 4} on a CoO base round about 900 deg. C. The oxidation of cobalt protoxide between 700 and 910 deg. C results in the building up, on the outside surface of CoO discs, of a usually continuous layer of Co{sub 3}O{sub 4}. Under certain conditions this surface reaction is accompanied by a reaction along the longitudinal symmetry plane of the sample where a layer of Co{sub 3}O{sub 4} of very irregular thickness builds up. (author) [French] Le processus d'oxydation superficielle du cobalt dans l'air obeit a une loi parabolique et peut etre caracterise, entre 750 et 1350 deg. C, par une energie d'activation de 41 000 calorie s /mole. Entre 400 et 900 deg. C, la pellicule d'oxyde est constituee de deux couches superposees de CoO, au contact du metal et de Co{sub 3}O{sub 4} en surface. Au-dessus de 900 deg. C, seul subsiste CoO. On a etudie les proprietes morphologiques de ces pellicules: anisotropie de croissance, facies de cristallisation, croissance des grains d'oxyde, texture, germination de Co{sub 3}O{sub 4} sur un support de CoO au voisinage de 900 deg. C. L'oxydation du protoxyde de cobalt entre 700 et 910 deg. C se traduit par l'edification, sur la surface exterieure des plaquettes de CoO, d'une couche en general continue de Co{sub 3}O{sub 4}. Dans certaines conditions, a cette reaction superficielle se superpose parfois une reaction suivant le plan de symetrie longitudinal de l'echantillon ou s'edifie alors une couche de Co{sub 3}O{sub 4} d'epaisseur tres irreguliere. (auteur)

Synthesis of cobalt boride nanoparticles using radio frequency thermal plasma

International Nuclear Information System (INIS)

Lapitan, Jr. Lorico DS.; Ying Ying Chen; Seesoek Choe; Watanabe, Takayuki

2012-01-01

Nano size cobalt boride particles were synthesized from vapor phase using a 30 kw-4 MHz radio frequency (RF) thermal plasma. Cobalt and boron powder mixtures used as precursors in different composition and feed rate were evaporated immediately in the high temperature plasma and cobalt boride nanoparticles were produced through the quenching process. The x-ray diffractometry (XRD) patterns of cobalt boride nanoparticles prepared from the feed powder ratio of 1:2 and 1:3 for Co: B showed peaks that are associated with the Co 2 B and CoB crystal phases of cobalt boride. The XRD analysis revealed that increasing the powder feed rate results in a higher mass fraction and a larger crystalline diameter of cobalt boride nanoparticles. The images obtained by field emission scanning electron microscopy (FE-SEM) revealed that cobalt boride nanoparticles have a spherical morphology. The crystallite size of the particles estimated with XRD was found to be 18-22 nm. (author)

Study to use graded cobalt adjuster in 540 MWe PHWR

International Nuclear Information System (INIS)

Raj, Manish; Fernando, M.P.S.; Pradhan, A.S.; Kumar, A.N.

2007-01-01

Full text: There are 17 adjusters in 540 MWe PHWR, which are essentially provided for xenon override function. They also provide flux flattening being in the central region of the reactor core. The present design of adjusters consists of stainless steel tube. The adjuster rods are grouped into 8 banks for movement. Since adjusters are normally fully inserted during reactor operation, they are best suited for production of cobalt 60. The nickel-plated cobalt in the form of either slugs or pellet are used for the design of cobalt pencils. The number of pencils can be varied to optimize the reactivity load and cobalt 60 production requirement. The worth and activity of cobalt adjusters have been worked out considering different pin configuration for the adjuster assembly. To start with we have assumed all adjusters throughout its length are of the same configuration. The flux depression factors within the cobalt pencils have been considered in the estimations of the specific and total cobalt 60 activities. The option of using graded cobalt adjusters, where different pin configuration along the length is considered for better flux flattening

The Use of Cobalt-Mediated Cycloisomerisation of Ynedinitriles in the Synthesis of Pyridazinohelicenes

Czech Academy of Sciences Publication Activity Database

Chercheja, Serghei; Klívar, Jiří; Jančařík, Andrej; Rybáček, Jiří; Salzl, Simon; Tarábek, Ján; Pospíšil, Lubomír; Vacek Chocholoušová, Jana; Vacek, Jaroslav; Pohl, Radek; Císařová, I.; Starý, Ivo; Stará, Irena G.

2014-01-01

Roč. 20, č. 27 (2014), s. 8477-8482 ISSN 0947-6539 R&D Projects: GA ČR(CZ) GAP207/10/2207 Institutional support: RVO:61388963 Keywords : cobalt * cyclization * helical structures * heterocycles * radicals Subject RIV: CC - Organic Chemistry Impact factor: 5.731, year: 2014

Reactivity of tris(acetylacetonato) iron(III) with tridentate [ONO] donor Schiff base as an access to newer mixed-ligand iron(III) complexes

Science.gov (United States)

Bhattacharjee, Chira R.; Goswami, Pankaj; Pramanik, Harun A. R.; Paul, Pradip C.; Mondal, Paritosh

2011-05-01

Two new mixed-ligand iron(III) complexes, [Fe(L n)(acac)(C 2H 5OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac) 3] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H 2L 1) or 2-aminobenzoic acid (H 2L 2). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L n)(acac)X] ( n = 1, 2; X = Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, 1H and 13C NMR spectroscopy. Room temperature magnetic susceptibility measurements ( μeff ˜ 5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (Δ Ep > 100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential ( E1/2) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level.

Investigations on bioaccumulation of cobalt by fish eggs

International Nuclear Information System (INIS)

Harms, U.; Behringer, H.; Kunze, J.

1978-01-01

In ionized form cobalt is taken up by fish eggs directly from the water. Accumulation takes place on the chorion where the metal ions are reversibly bound to functional groups of the protein of the envelope of the egg or of the mycosa. To a small extent there occurs a transport of metal ions into the interior of the egg. It could not be clarified within the scope of the studies performed if this process is to be attributed to diffusion. Binding of the cobalt ions to the chorion leads, within hours, to a nearly uncharged final state, an apparent equilibrium, whose position is determined by the cobalt ion concentration of the breeding medium. Foreign ions (electrolytes like Ca 2+ ) lead to reduced uptake of cobalt ions, because they compete with the latter for binding places in the egg's envelope. Complex-forming substances (cysteine) result in lower absorption rates, too, the concentration of available cobalt ions in the water being reduced. (orig.) [de

Zirconium amine tris(phenolate): A more effective initiator for biomedical lactide.

Science.gov (United States)

Jones, Matthew D; Wu, Xujun; Chaudhuri, Julian; Davidson, Matthew G; Ellis, Marianne J

2017-11-01

Here a zirconium amine tris(phenolate) is used as the initiator for the production of polylactide for biomedical applications, as a replacement for a tin initiator (usually tin octanoate). The ring opening polymerization (ROP) was carried out in the melt at 130°C. The zirconium-catalyzed PLA (PLA-Zr) required 30min, resulting in a polydispersity index (PDI) of 1.17, compared to 1h and PDI=1.77 for tin-catalyzed PLA (PLA-Sn). PLA-Zr and PLA-Sn supported osteosarcoma cell (MG63) culture to the same extent (cell number, morphology, extracellular matrix production and osteogenic function) until day 14 when the PLA-Zr showed increased cell number, overall extracellular matrix production and osteogenic function. To conclude, the reduction in reaction time, controllable microstructure and biologically benign nature of the zirconium amine tris(phenolate) initiator shows that it is a more effective initiator for ROP of polylactide for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Measurement for cobalt target activity and its axial distribution

International Nuclear Information System (INIS)

Li Xingyuan; Chen Zigen.

1985-01-01

Cobalt target activity and its axial distribution are measured in process of producing radioactive isotopes 60 Co by irradiation in HFETR. Cobalt target activity is obtained with measured data at 3.60 m and 4.60 m, relative axial distribution of cobalt target activity is obtained with one at 30 cm, and axial distribution of cobalt target activity(or specific activity) is obtained with both of data. The difference between this specific activity and measured result for 60 Co teletherapy sources in the end is less than +- 5%

Association of Eu(III) and Cm(III) with Bacillus subtilis and Halobacterium salinarum

International Nuclear Information System (INIS)

Ozaki, Takuo; Kimura, Takaumi; Ohnuki, Toshihiko; Yoshida, Zenko

2002-01-01

Adsorption behavior of Eu(III) and Cm(III) by Bacillus subtilis and Halobacterium salinarum was investigated. Both microorganisms showed almost identical pH dependence on the distribution ratio (K d ) of the metals examined, i.e., K d of Eu(III) and Cm(III) increased with an increase of pH. The coordination state of Eu(III) adsorbed on the microorganisms was studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS). The coordination states of Eu(III) adsorbed on the B. subtilis and H. salinarum was of different characteristics. H. salinarum exhibited more outer-spherical interaction with Eu(III) than B. subtilis. (author)

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

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg. No...

cis-Bromido(methylaminebis(propane-1,3-diaminecobalt(III dibromide

Directory of Open Access Journals (Sweden)

P. S. Kannan

2013-07-01

Full Text Available In the title compound, [CoBr(CH5N(C3H10N22]Br2, the cobaltIII ion has a distorted octahedral coordination environment and is surrounded by four N atoms in the equatorial plane, with an additional N atom and the Br atom occupying the axial positions. In the crystal, the complex cation and the two counter anions are linked via N—H...Br and C—H...Br hydrogen bonds, forming a three-dimensional network.

Characterization and Catalytic Activity of Montmorillonite K10-Supported Cobalt Catalysts

International Nuclear Information System (INIS)

Gobara, H.M.; Ghattas, M.S.; Henien, S.A.

2010-01-01

Montmorillonite K10-supported cobalt catalysts were prepared by wet impregnation method. The samples were analyzed by XRD, TPR, FTTR and BET characterization techniques. [Three phases of cobalt species were identified namely, cobalt oxide (Co 3 O 4 ), cobalt silicate (Co 2 S 1 O 4 ) and cobalt aluminate (CoAl 2 O 4 ). These species were most probably existing within the inter lamellar spaces of the meso porous montmorillonite K10 support]. The two bands observed at 1385 and 760 cm 1 were characteristic of metal species rather than the support, being mostly of Co - O bond vibration. The hysteresis loop, pore size distribution, pore volume and BET surface area were greatly affected by cobalt loading. The catalyst containing 18 wt% cobalt was the most selective sample for ethylene production from ethanol dehydration.

Madagascar, politique forestière : Bilan 1990 – 2013 et propositions

African Journals Online (AJOL)

1 juin 2014 ... L'accès est libre car les agents forestiers sont trop peu nombreux, mal payés ..... solutions plus durables, déjà testées et mieux maîtrisées. (iii) Les dégradations des ...... trafic de bois de rose malgache. In: Madagascar, le ...

Hydrothermal synthesis, crystal structure and properties of a novel chain coordination polymer constructed by tetrafunctional phosphonate anions and cobalt ions

International Nuclear Information System (INIS)

Guan, Lei; Wang, Ying

2015-01-01

A novel cobalt phosphonate, [Co(HL)(H 2 O) 3 ] n (1) (L=N(CH 2 PO 3 H) 3 3− ) has been synthesized by hydrothermal reaction at 150 °C and structurally characterized by X-ray diffraction, infrared spectroscopy, elemental and thermogravimetric analysis. Complex 1 features a 1D chain structure with double-channel built from CoO 6 octahedra bridged together by the phosphonate groups. Each cobalt ion is octahedrally coordinated by three phosphonate oxygen atoms and three water molecules. The coordinated water molecules can form the hydrogen bonds with the phosphonate oxygen atoms to link the 1D chains, building a 2D layered structure, further resulting in a 3D network. The luminescence spectrum indicates an emission maximum at 435 nm. The magnetic susceptibility curve exhibits a dominant antiferromagnetic behavior with a weakly ferromagnetic component at low temperatures. - Graphical abstract: The connectivity between cobalt ions and the ligands results in a chain structure with a 1D double-channel structure, which is constructed by A-type subrings and B-type subrings. - Highlights: • The tetrafunctional phosphonate ligand was used as the ligand. • A novel chain structure can be formed by A-type rings and B-type rings. • Two types of rings can form a 1D double-channel structure, along the c-axis

Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

Science.gov (United States)

Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

Effect of thermal annealing on the structural and optical properties of tris-(8-hydroxyquinoline)aluminum(III) (Alq3 ) films.

Science.gov (United States)

Cuba, M; Muralidharan, G

2015-05-01

Tris-(8-hydroxyquionoline)aluminum (Alq3 ) was synthesized and coated on to a glass substrate using the dip coating method. The structural and optical properties of the Alq3 film after thermal annealing from 50°C to 300°C in 50° steps was studied. The films have been prepared with 2 to 16 layers (42-324 nm). The thickness and thermal annealing of Alq3 films were optimized for maximum luminescence yield. The Fourier transform infrared spectrum confirms the formation of quinoline with absorption in the region 700 - 500/cm. Partial sublimation and decomposition of quinoline ion was observed with the Alq3 films annealed at 300°C. The X-ray diffraction pattern of the Alq3 film annealed at 50°C to 150°C reveals the amorphous nature of the films. The Alq3 film annealed above 150°C were crystalline nature. Film annealed at 150°C exhibits a photoluminescence intensity maximum at 512 nm when excited at 390 nm. The Alq3 thin film deposited with 10 layers (220 nm) at 150°C exhibited maximum luminescence yield. Copyright © 2014 John Wiley & Sons, Ltd.

Fabrication of a PVC membrane samarium(III) sensor based on N,N Prime ,N Double-Prime -tris(4-pyridyl)trimesic amide as a selectophore

Energy Technology Data Exchange (ETDEWEB)

Zamani, Hassan Ali, E-mail: haszamani@yahoo.com [Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Naghavi-Reyabbi, Fatemeh [Resident of General Surgery, Endoscopic and Minimaly Invasive Surgery Research Center, Ghaem Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Faridbod, Farnoush [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Mohammadhosseini, Majid [Department of Chemistry, Faculty of Basic Sciences, Shahrood Branch, Islamic Azad University, Shahrood (Iran, Islamic Republic of); Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Tadjarodi, Azadeh; Rad, Maryam [Department of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

2013-03-01

A new ion-selective electrode for Sm{sup 3+} ion is described based on the incorporation of N,N Prime ,N Double-Prime -tris(4-pyridyl)trimesic amide (TPTA) in a poly(vinylchloride) (PVC) matrix. The membrane sensor comprises nitrobenzene (NB) as a plasticizer, and oleic acid (OA) as an anionic additive. The sensor with the optimized composition shows a Nernstian potential response of 19.8 {+-} 0.5 mV decade{sup -1} over a wide concentration range of 1.0 Multiplication-Sign 10{sup -2} and 1 Multiplication-Sign 10{sup -6} mol L{sup -1}, with a lower detection limit of 4.7 Multiplication-Sign 10{sup -7} mol L{sup -1} and satisfactor applicable pH range of 3.6-9.2. Having a short response time of less than 10 s and a very good selectivity towards the Sm{sup 3+} over a wide variety of interfering cations (e.g. alkali, alkaline earth, transition and heavy metal ions) the sensor seemed to be a promising analytical tool for determination of the Sm{sup 3+}. Hence, it was used as an indicator electrode in the potentiometric titration of samarium ion with EDTA. It was also applied to the direct samarium recovery in binary mixtures. - Highlights: Black-Right-Pointing-Pointer A new Sm{sup 3+}-PVC membrane sensor is introduced for determination of Sm{sup 3+} ions in the solutions. Black-Right-Pointing-Pointer N,N Prime ,N Double-Prime -tris(4-pyridyl)trimesic amide was used as a suitable selectophore for samarium sensor. Black-Right-Pointing-Pointer Detection limit of the sensor is 4.7 Multiplication-Sign 10{sup -7} mol L{sup -1} with a short response time of less than 10 s.

COORDINATION COMPOUNDS OF 3D-METALS ACETYLACETONATES WITH THIOSEMICARBAZIDE

Directory of Open Access Journals (Sweden)

T. V. Koksharova

2015-03-01

Full Text Available Coordination Compounds of 3d-Metals acetylacetonates with Thiosemicarbazide were synthesized. Their physical and chemical properties and structure were studied by conductometry, IR spectroscopy, electronic spectroscopy, magnetochemistry and thermo-gravimetricstudies. The complexes compositions correspond to the formulas Co(L2(Acac and M(L(Acac, where M = Cu, Ni, Zn, HL is thiosemicarbazide, HAcac is acetylacetone. All of them are nonelectrolytes. Thiosemicarbazide is deprotonated and coordinated through the nitrogen and sulphur atoms with the formation of four-membered ring in all cases. Acetylacetonate co-ordination mode does not change at acetylacetonates with Thiosemicarbazide interaction. Copper(II and nickel(II complexes have square-planar structure, and cobalt(III complex is octahedral.

Highly selective cobalt-catalyzed hydrovinylation of styrene

NARCIS (Netherlands)

Grutters, M.M.P.; Müller, C.; Vogt, D.

2006-01-01

The hydrovinylation reaction is a codimerization of a 1,3-diene or vinyl arene and ethene with great potential for fine chemicals and pharmaceuticals. For the first time, enantioselective cobalt-catalyzed hydrovinylations of styrene were achieved with a cobalt-based system bearing a chiral

Relationship between the nuclear resonance of cobalt metal and its ferromagnetic properties; Relations entre la resonance nucleaire du cobalt metallique et ses proprietes ferromagnetiques

Energy Technology Data Exchange (ETDEWEB)

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

1964-05-15

resulte du couplage intense existant entre les noyaux et les electrons porteurs du magnetisme. Ces derniers excitent les noyaux et, dans les parois de Bloch, les soumettent a un champ radio-frequence bien plus intense que le champ RF applique. Les parametres de la resonance se determinent alors a partir du mouvement des parois, et dependent donc des constantes ferromagnetiques. La theorie permet de prevoir quantitativement certains effets particuliers, notamment par action d'un champ magnetique continu ou de la temperature. L'etude expeimentale a porte sur des poudres de cobalt et est en bon accord avec la theorie. Toutefois il faut tenir compte de l'effet de peau et reviser la theorie en consequence. Ceci permet d'expliquer certaines divergences observees, ainsi que l'influence de la taille des grains et celle du champ magnetique sur la forme de raie. Des renseignements originaux ont ete obtenus sur certaines proprietes purement ferromagnetiques du cobalt, en etudiant l'effet d'un champ magnetique et cette methode a pu etre appliquee a d'autres corps ferromagnetiques. En raison du caractere particulier de cette resonance nucleaire, qui se produit en l'absence de champ directeur et possede une importante largeur de raie, des spectrographes de type nouveau ont ete realises qui ont rendu possible des mesures precises de la forme de raie. La faible intensite des signaux obtenus dans certains cas a conduit a la mise au point d'une methode originale d'extraction dont la theorie et les applications pratiques sont donnees ici. L'ensemble de ces experiences fait apparaitre la resonance nucleaire comme un puissant moyen d'etude du ferromagnetique permettant de deceler des phenomenes microscopiques difficilement accessibles par les methodes classiques. (auteur)

Relationship between the nuclear resonance of cobalt metal and its ferromagnetic properties; Relations entre la resonance nucleaire du cobalt metallique et ses proprietes ferromagnetiques

Energy Technology Data Exchange (ETDEWEB)

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

1964-05-15

couplage intense existant entre les noyaux et les electrons porteurs du magnetisme. Ces derniers excitent les noyaux et, dans les parois de Bloch, les soumettent a un champ radio-frequence bien plus intense que le champ RF applique. Les parametres de la resonance se determinent alors a partir du mouvement des parois, et dependent donc des constantes ferromagnetiques. La theorie permet de prevoir quantitativement certains effets particuliers, notamment par action d'un champ magnetique continu ou de la temperature. L'etude expeimentale a porte sur des poudres de cobalt et est en bon accord avec la theorie. Toutefois il faut tenir compte de l'effet de peau et reviser la theorie en consequence. Ceci permet d'expliquer certaines divergences observees, ainsi que l'influence de la taille des grains et celle du champ magnetique sur la forme de raie. Des renseignements originaux ont ete obtenus sur certaines proprietes purement ferromagnetiques du cobalt, en etudiant l'effet d'un champ magnetique et cette methode a pu etre appliquee a d'autres corps ferromagnetiques. En raison du caractere particulier de cette resonance nucleaire, qui se produit en l'absence de champ directeur et possede une importante largeur de raie, des spectrographes de type nouveau ont ete realises qui ont rendu possible des mesures precises de la forme de raie. La faible intensite des signaux obtenus dans certains cas a conduit a la mise au point d'une methode originale d'extraction dont la theorie et les applications pratiques sont donnees ici. L'ensemble de ces experiences fait apparaitre la resonance nucleaire comme un puissant moyen d'etude du ferromagnetique permettant de deceler des phenomenes microscopiques difficilement accessibles par les methodes classiques. (auteur)

Cobalt Blues The Story of Leonard Grimmett, the Man Behind the First Cobalt-60 Unit in the United States

CERN Document Server

Almond, Peter R

2013-01-01

For the latter half of the 20th century, cobalt-60 units were the mainstay of radiation treatments for cancer. Cobalt Blues describes the development of the first cobalt-60 unit in the United States and the man behind it, Leonard Grimmett. Conceptually conceived before World War II, it only became possible because of the development of nuclear reactors during the war. Although Grimmett conceived of and published his ideas first, the Canadians built the first units because of the capability of their reactor to produce more suitable cobalt-60 sources. This book tells the story of how Grimmett and others came together at the time that the U S Atomic Energy Agency was pushing the use of radioactivity in medicine. Due to his sudden death, very little information about Grimmett was known until recently, when various documents have come to light, allowing the full story to be told.

One-step prepared cobalt-based nanosheet as an efficient heterogeneous catalyst for activating peroxymonosulfate to degrade caffeine in water.

Science.gov (United States)

Lin, Kun-Yi Andrew; Lai, Hong-Kai; Tong, Shaoping

2018-03-15

Two-dimensional (2D) planar cobalt-containing materials are promising catalysts for activating peroxymonosulfate (PMS) to degrade contaminants because 2D sheet-like morphology provides large reactive surfaces. However, preparation of these sheet-supported cobaltic materials typically involves multiple steps and complex reagents, making them less practical for PMS activation. In this study, a cobalt-based nanosheet (CoNS) is particularly developed using a one-step hydrothermal process with a single reagent in water. The resulting CoNS can exhibit a thickness as thin as a few nanometers and 2-D morphology. CoNS is also primarily comprised of cobalt species in a coordinated form of Prussian Blue analogue, which consists of both Co 3+ and Co 2+ . These features make CoNS promising for activating PMS in aqueous systems. As degradation of an emerging contaminant, caffeine, is selected as a representative reaction, CoNS not only successfully activates PMS to fully degrade caffeine in 20 min but also exhibits a much higher catalytic activity than the most common PMS activator, Co 3 O 4 . Via studying inhibitive effects of radical scavengers, caffeine degradation by CoNS-activated PMS is primarily attributed to sulfate radicals and hydroxyl radicals to a lesser extent. The degradation products of caffeine by CoNS-activated PMS are also identified and a potential degradation pathway is proposed. Moreover, CoNS could be also re-used to activate PMS for caffeine degradation without activity loss. These results indicate that CoNS is a conveniently prepared and highly effective and stable 2-D catalyst for aqueous chemical oxidation reactions. Copyright © 2017. Published by Elsevier Inc.

Nanostructured TiO2/CH3NH3PbI3 heterojunction solar cells employing spiro-OMeTAD/Co-complex as hole-transporting material

KAUST Repository

Noh, Jun Hong

2013-01-01

For using 2,2′,7,7′-tetrakis(N,N′-di-p- methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a hole conductor in solar cells, it is necessary to improve its charge-transport properties through electrochemical doping. With the aim of fabricating efficient mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cells, we used tris[2-(1H-pyrazol-1-yl)-4-tert- butylpyridine)cobalt(iii) tris(bis(trifluoromethylsulfonyl) imide)] (FK209) as a p-dopant for spiro-OMeTAD. The mixture of spiro-OMeTAD, FK209, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI), and 4-tert-butylpyridine (TBP) exhibited significantly higher performance than mixtures of pristine spiro-OMeTAD, spiro-OMeTAD, and FK209, and spiro-OMeTAD, Li-TFSI, and TBP. Such a synergistic effect between the Co-complex and Li-TFSI in conjunction with spiro-OMeTAD effectively improved the power conversion efficiency (PCE) of the fabricated solar cells. As a result, we achieved PCE of 10.4%, measured under standard solar conditions (AM 1.5G, 100 mW cm-2). © 2013 The Royal Society of Chemistry.

D III-D divertor target heat flux measurements during Ohmic and neutral beam heating

International Nuclear Information System (INIS)

Hill, D.N.; Petrie, T.; Mahdavi, M.A.; Lao, L.; Howl, W.

1988-01-01

Time resolved power deposition profiles on the D III-D divertor target plates have been measured for Ohmic and neutral beam injection heated plasmas using fast response infrared thermography (τ ≤ 150 μs). Giant Edge Localized Modes have been observed which punctuate quiescent periods of good H-mode confinement and deposit more than 5% of the stored energy of the core plasma on the divertor armour tiles on millisecond time-scales. The heat pulse associated with these events arrives approximately 0.5 ms earlier on the outer leg of the divertor relative to the inner leg. The measured power deposition profiles are displaced relative to the separatrix intercepts on the target plates, and the peak heat fluxes are a function of core plasma density. (author). Letter-to-the-editor. 11 refs, 7 figs

Isotopic exchange rate of cobalt ions between hydrous tin(IV) oxide and aqueous solutions

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi; Itami, Akira

1989-01-01

The isotopic exchange rate of cobalt ions between hydrous tin(IV) oxide ion exchanger and aqueous solutions was radiochemically measured to obtain fundamental data which are useful for elucidating the ion-exchange kinetics of the material for the transition metal elements. The rate can be understood by considering that the cobalt ions were present in the exchanger as three kinds of species: (A 1 ) Free ions which can diffuse in the exchanger particles, (A 2 ) Weakly bound ions to the exchange sites which exchange rapidly with A 1 , and (B) Covalently fixed ions to the exchange sites which exchange very slowly with A 1 . At low fraction of B, the rate is controlled by the diffusion of A 1 with the effective diffusion coefficient, D eff , the values of which depend on the concentration ratios of A 2 to A 1 . When B predominates over the A species, the concentration ratios of B to A 1 affect greatly D eff . The values of D eff and their activation energy(20 kJ/mol) were also estimated

Sputtering on cobalt with noble gas ions

International Nuclear Information System (INIS)

Sarholt-Kristensen, L.; Johansen, A.; Johnson, E.

1983-01-01

Single crystals of cobalt have been bombarded with 80 keV Ar + ions and with 80 keV and 200 keV Xe + ions in the [0001] direction of the hcp phase and the [111] direction of the fcc phase. The sputtering yield has been measured as function of target temperature (20 0 C-500 0 C), showing a reduction in sputtering yield for 80 keV Ar + ions and 200 keV Xe + ions, when the crystal structure changes from hcp to fcc. In contrast to this, bombardment with 80 keV Xe + ions results in an increase in sputtering yield as the phase transition is passed. Sputtering yields for [111] nickel are in agreement with the sputtering yields for fcc cobalt indicating normal behaviour of the fcc cobalt phase. The higher sputtering yield of [0001] cobalt for certain combinations of ion mass and energy may then be ascribed to disorder induced partly by martensitic phase transformation, partly by radiation damage. (orig.)

Enhanced piezoelectric properties and excellent thermal stabilities of cobalt-modified Aurivillius-type calcium bismuth titanate (CaBi_4Ti_4O_1_5)

International Nuclear Information System (INIS)

Zhao, Tian-Long; Wang, Chun-Ming; Wang, Chun-Lei; Wang, Yi-Ming; Dong, Shuxiang

2015-01-01

Highlights: • Cobalt oxide modified CBT-based ceramics were prepared and investigated in detail. • XRPD analysis revealed Co ions enter into B-site of CBT-based ceramics. • CBT-Co4 ceramics show the enhanced d_3_3 of 14 pC/N and T_c of 782 °C. • CBT-Co4 ceramics present the improved high-temperature resistivity. • Thermal depoling behavior indicates CBT-Co4 ceramics exhibit good thermal stability. - Abstract: Bismuth layer-structured ferroelectric (BLSF) calcium bismuth titanate (CaBi_4Ti_4O_1_5, CBT) piezoelectric ceramics with 0.0–1.0 wt.% cobalt oxide (Co_2O_3) have been prepared via a conventional solid-state reaction method. Microstructural morphology and electrical properties of cobalt oxide-modified CBT ceramics were investigated in detail. X-ray powder diffraction (XRPD) analysis revealed that the cobalt oxide-modified CBT ceramics have a pure four-layer Aurivillius-type structure. The piezoelectric properties of CBT ceramics were significantly enhanced by cobalt oxide modifications. The piezoelectric coefficient d_3_3 and Curie temperature T_c of 0.2 wt.% cobalt oxide-modified CBT ceramics (CBT-Co4) are 14 pC/N and 782 °C, respectively. The DC resistivity and thermal depoling behavior at elevated temperature indicated that the CBT-Co4 ceramics exhibit good thermal stability, demonstrating that the CBT-Co4 ceramics are potential materials for high temperature piezoelectric applications.

Simulating the synthesis and thermodynamic characteristics of the desolvation of lanthanide borohydride tris-Tetrahydrofuranates

Science.gov (United States)

Gafurov, B. A.; Mirsaidov, I. U.; Nasrulloeva, D. Kh.; Badalov, A.

2013-10-01

Lanthanide borohydride tris-tetrahydrofuranates (Ln(BH4) · 3THF, where THF is tetrahydrofuran and Ln is La, Nd, Sm, Gd, Er, Yb, and Lu) is synthesized via the exchange reaction of lanthanide(III) chloride and sodium borohydride in THF. It is found that synthesis proceeds according to a stepwise mechanism and the product of the reaction (lanthanide borohydride) initiates the process. The two-step character of the desolvation of Ln(BH4)3 · 3THF under steady-state conditions in the temperature range of 300 to 400 K is determined through X-ray phase and chemical analyses, tensiometry, and gas volumetry. It is established that one mole and then two moles of THF are removed from the initial sample at the first and second steps, respectively. Equations for barograms are obtained and the thermodynamic characteristics of desolvation of Ln(BH4)3 · 3THF under study are calculated. Gibbs energy values of the stages of process are determined semi-empirically. The law of its change for the entire series of Ln(BH4)3 · 3THF is determined with the emergence of the tetrad effect.

Correlation of reactivity with structural factors in a series of Fe(II) substituted cobalt ferrites

International Nuclear Information System (INIS)

Sileo, Elsa E.; Garcia Rodenas, Luis; Paiva-Santos, Carlos O.; Stephens, Peter W.; Morando, Pedro J.; Blesa, Miguel A.

2006-01-01

A series of powdered cobalt ferrites, Co x Fe 3- x O 4 with 0.66≤x II , were synthesized by a mild procedure, and their Fe and Co site occupancies and structural characteristics were explored using X-ray anomalous scattering and the Rietveld refinement method. The dissolution kinetics, measured in 0.1 M oxalic acid aqueous solution at 70 deg. C, indicate in all cases the operation of a contracting volume rate law. The specific rates increased with the Fe II content following approximately a second-order polynomial expression. This result suggests that the transfer of Fe III controls the dissolution rate, and that the leaching of a first layer of ions Co II and Fe II leaves exposed a surface enriched in slower dissolving octahedral Fe III ions. Within this model, inner vicinal lattice Fe II accelerates the rate of Fe III transfer via internal electron hopping. A chain mechanism, involving successive electron transfers, fits the data very well. - Graphical abstract: The electron exchange between octahedral Fe II and Fe III ions has important consequences on the specific dissolution rates. Display Omitted

High-performance III-V MOSFET with nano-stacked high-k gate dielectric and 3D fin-shaped structure.

Science.gov (United States)

Chen, Szu-Hung; Liao, Wen-Shiang; Yang, Hsin-Chia; Wang, Shea-Jue; Liaw, Yue-Gie; Wang, Hao; Gu, Haoshuang; Wang, Mu-Chun

2012-08-01

A three-dimensional (3D) fin-shaped field-effect transistor structure based on III-V metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication has been demonstrated using a submicron GaAs fin as the high-mobility channel. The fin-shaped channel has a thickness-to-width ratio (TFin/WFin) equal to 1. The nano-stacked high-k Al2O3 dielectric was adopted as a gate insulator in forming a metal-oxide-semiconductor structure to suppress gate leakage. The 3D III-V MOSFET exhibits outstanding gate controllability and shows a high Ion/Ioff ratio > 105 and a low subthreshold swing of 80 mV/decade. Compared to a conventional Schottky gate metal-semiconductor field-effect transistor or planar III-V MOSFETs, the III-V MOSFET in this work exhibits a significant performance improvement and is promising for future development of high-performance n-channel devices based on III-V materials.

Direct Probing of Carrier Behavior in Electroluminescence Indium-Zinc-Oxide/N,N '-Di-[(1-naphthyl)-N,N '-diphenyl]-(1,1'-biphenyl)-4,4'-diamine/Tris(8-hydroxy-quinolinato)aluminum(III)/LiF/Al Diode by Time-Resolved Optical Second-Harmonic Generation

Science.gov (United States)

Taguchi, Dai; Zhang, Le; Li, Jun; Weis, Martin; Manaka, Takaaki; Iwamoto, Mitsumasa

2011-04-01

By using electric-field-induced second-harmonic generation (EFISHG) measurement, we probed charging and discharging in an α-NPD/Alq3 organic light-emitting diode [α-NPD, N,N '-di-[(1-naphthyl)-N,N '-diphenyl]-(1,1'-biphenyl)-4,4'-diamine; Alq3, tris(8-hydroxy-quinolinato)aluminum(III)] while electroluminescence response was monitored. The EFISHG measurement showed that excessive positive charges accumulated at the α-NPD/Alq3 interface in the charging process, accompanying electroluminescence (EL) radiation, and the accumulated excess positive charges disappeared in the discharging process before the EL decayed. Note that the EL radiation was smooth and strong under the high voltage application, while the EL decayed in a similar way. The Maxwell-Wagner model analysis showed no-dependence of the accumulated excessive positive charge on the applied external voltage, suggesting that electrons and holes injected from the opposite electrodes for EL radiation balanced at the interface. The EFISHG measurement will be useful as a direct way to probe carrier behaviors in organic EL devices.

Atomic layer deposition of cobalt carbide films and their magnetic properties using propanol as a reducing agent

Energy Technology Data Exchange (ETDEWEB)

Sarr, Mouhamadou, E-mail: sarrtapha44@yahoo.fr [Luxembourg Instituteof Science and Technology, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Bahlawane, Naoufal; Arl, Didier [Luxembourg Instituteof Science and Technology, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Dossot, Manuel [Laboratory of Physical Chemistry and Microbiology for the Environment, UMR 7564 CNRS-Université de Lorraine, 405 rue de Vandoeuvre, 54601 Villers-lès-Nancy (France); McRae, Edward [Institut Jean Lamour, UMR 7198CNRS-Université de Lorraine, FST, BP 70239, 54506 Vandoeuvre-lès-Nancy (France); Lenoble, Damien, E-mail: damien.lenoble@list.lu [Luxembourg Instituteof Science and Technology, 41, rue du Brill, L-4422 Belvaux (Luxembourg)

2016-08-30

Highlights: • Conformal carbon-Co-carbide thin films. • Chemically growth carbone-Co-carbide composite. • Tuneable magnetic properties. - Abstract: The investigation of highly conformal thin films using Atomic Layer Deposition (ALD) is driven by a variety of applications in modern technologies. In particular, the emergence of 3D memory device architectures requires conformal materials with tuneable magnetic properties. Here, nanocomposites of carbon, cobalt and cobalt carbide are deposited by ALD using cobalt acetylacetonate with propanol as a reducing agent. Films were grown by varying the ALD deposition parameters including deposition temperature and propanol exposure time. The morphology, the chemical composition and the crystalline structure of the cobalt carbide film were investigated. Vibrating Sample Magnetometer (VSM) measurements revealed magnetic hysteresis loops with a coercivity reaching 500 Oe and a maximal saturation magnetization of 0.9 T with a grain size less than 15 nm. Magnetic properties are shown to be tuneable by adjusting the deposition parameters that significantly affect the microstructure and the composition of the deposited films.

Near-infrared electroluminescence from double-emission-layers devices based on Ytterbium (III) complexes

International Nuclear Information System (INIS)

Li Zhefeng; Zhang Hongjie; Yu Jiangbo

2012-01-01

We investigated near-infrared electroluminescence properties of two lanthanide complexes Yb(PMBP) 3 Bath [PMBP = tris(1-phenyl-3-methyl-4-(4-tert-butylbenzacyl)-5-pyrazolone); Bath = bathophenanthroline] and Yb(PMIP) 3 TP 2 [PMIP = tris(1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone); TP = triphenyl phosphine oxide] by fabricated the double-emission-layers devices. From the device characteristics, it is known that holes are easier to transport in Yb(PMIP) 3 TP 2 layer and electrons are easier to transport in Yb(PMBP) 3 Bath layer, at the same time, both of the two complexes can be acted as emission layers in the device. The recombination region of carriers has been confined in the interface of Yb(PMIP) 3 TP 2 /Yb(PMBP) 3 Bath, and pure Yb 3+ ion characteristic emission centered at 980 nm has been obtained. The device shows the maximum near-infrared irradiance as 14.7 mW/m 2 at the applied voltage of 17.8 V. - Highlights: ► Near-infrared electroluminescent devices with Yb(III) complexes as emission layers. ► Double-emission layer device structure introduced to balance carriers. ► Improved performance of double-emission layer device.

In situ preparation of cobalt nanoparticles decorated in N-doped carbon nanofibers as excellent electromagnetic wave absorbers.

Science.gov (United States)

Liu, Huihui; Li, Yajing; Yuan, Mengwei; Sun, Genban; Li, Huifeng; Ma, Shulan; Liao, Qingliang; Zhang, Yue

2018-06-11

The electrospinning and annealing methods is applied to prepare cobalt nanoparticles decorated in N-doped carbon nanofibers (Co/N-C NFs) with solid and macroporous structures. In detail, the nanocomposites are synthesized by carbonization of as-electrospun polyacrylonitrile (PAN)/cobalt acetylacetonate nanofibers in an argon atmosphere. The solid Co/N-C NFs has lengths up to dozens of microns with the average diameter of ca. 500 nm and possess abundant cobalt nanoparticles on both the surface and within the fibers, and the cobalt nanoparticles size is about 20 nm. The macroporous Co/N-C NFs possess a hierarchical pore structure, and there are macropores (500 nm) and mesopores (2-50 nm) existed in this material. The saturation magnetization (Ms) and coercivity (Hc) of the solid Co/N-C NFs are 28.4 emu g-1 and 661 Oe, respectively. And those of the macroporous Co/N-C NFs are 23.3 emu g-1 and 580 Oe, respectively. The solid Co/N-C NFs exhibits excellent electromagnetic wave absorbability, a minimum reflection loss (RL) value of -25.7 dB is achieved with a matching thickness of 2 mm for solid Co/N-C NFs when the filler loading is 5 wt%, and the effective bandwidth (BW) (RL≤-10 dB) is 4.3 GHz. Moreover, the effective microwave absorption can be achieved in the whole range of 1-18 GHz by adjusting the thickness of the sample layer and content of the dopant sample.

Detection of endonuclease III- and 8-oxoguanine glycosylase-sensitive base modifications in γ-irradiated DNA and cells by the aldehyde reactive probe (ARP) assay

International Nuclear Information System (INIS)

Mohsin Ali, M.; Kurisu, Satofumi; Yoshioka, Yoshihiro; Terato, Hiroaki; Ohyama, Yoshihiko; Ide Hiroshi; Kubo, Kihei

2004-01-01

Ionizing radiation generates diverse DNA lesions that differentially induce cell death and mutations. In the present study, calf thymus DNA (400 μg/ml) and HeLa cells were irradiated by 60 Co γ-rays, and abasic (AP) sites and endonuclease (Endo) III- and 8-oxoguanine glycosylase (hOGG1)-sensitive base modifications in DNA were quantitated by the aldehyde reactive probe (ARP) assay. The irradiation of calf thymus DNA in phosphate buffer generated 91 Endo III- and 100 hOGG1-sensitive base modifications and 110 AP sites per 10 6 base pairs (bp) per Gy. The yield of the lesions in Tris buffer was 41- to 91-fold lower than that in phosphate, demonstrating a radioprotective effect of Tris. The HeLa cell chromosomal DNA contained 12 Endo III- and 3.8 hOGG1-sensitive base modifications and less than 1 AP sites per 10 6 bp as endogenous damage, and their level was increased by irradiation. The yields of the damage at 1 Gy (roughly equivalent to the lethal dose of HeLa cells [1.6-1.8 Gy]) were 0.13 Endo III, 0.091 hOGG1, and 0.065 AP sites per 10 6 bp, showing that irradiation with a lethal dose brought about only a marginal increase in base damage relative to an endogenous one. A comparison of the present data with those reported for DNA strand breaks supports the primary importance of double-strand breaks and clustered lesions as lethal damages formed by ionizing radiation. (author)

High-solid mesophilic methane fermentation of food waste with an emphasis on Iron, Cobalt, and Nickel requirements.

Science.gov (United States)

Qiang, Hong; Lang, Dong-Li; Li, Yu-You

2012-01-01

The effect of trace metals on the mesophilic methane fermentation of high-solid food waste was investigated using both batch and continuous experiments. The continuous experiment was conducted by using a CSTR-type reactor with three run. During the first run, the HRT of the reactor was stepwise decreased from 100 days to 30 days. From operation day 50, the reactor efficiency deteriorated due to the lack of trace metals. The batch experiment showed that iron, cobalt, and nickel combinations had a significant effect on food waste. According to the results of the batch experiment, a combination of iron, cobalt, and nickel was added into the CSTR reactor by two different methods at run II, and III. Based on experimental results and theoretical calculations, the most suitable values of Fe/COD, Co/COD, and Ni/COD in the substrate were identified as 200, 6.0, and 5.7 mg/kg COD, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

New results on charmed D, F+- and F* production and decay from the Mark III

International Nuclear Information System (INIS)

Schindler, R.H.

1986-09-01

Results on charmed meson production and decay are presented from the Mark III at SPEAR. F anti F* associated production is observed allowing a direct measurement of the F* mass. A search for the decay D + → μ + nu/sub μ/ in the recoil of hadronically tagged D +- decays provides a stringent limit on the pseudoscalar decay constant f/sub D/. New results on D 0 anti D 0 mixing from semileptonic D 0 decays and evidence for a nonresonant component in D/sub e4/ decays are also presented

A laboratory and field evaluation of the mobility of cobalt-60/EDTA

International Nuclear Information System (INIS)

Jones, T.L.; Gee, G.W.; Kirkham, R.R.; Swanson, J.L.

1983-01-01

We have observed a time and soil type dependence in the ability of the organic complexant EDTA to keep cobalt-60 in solution. Test results indicate that short-term adsorption tests lasting 5 days or less can be misleading. In short-term tests using cobalt-60/EDTA and soil from the Hanford site, low sorption in batch tests and high mobility in column tests were observed. During long-term batch test using cobalt-60/EDTA, the percentage of cobalt remaining in solution decreased from 90% after 7 days to less than 10% after 500 days. In laboratory and field column tests where low water flow rates allowed long contact time, virtually no cobalt movement was observed even though in the field test tritium was transported over 4 meters. Long-term batch tests using cobalt-60/EDTA and soil from Savannah River burial grounds showed that cobalt remainin in solution dropped to 30% of the total cobalt added after 5 days and to less than 1% after 15 days. Batch tests using soil from Oak Ridge burial grounds were less dramatic showing cobalt in solution decreasing from 90% after 5 days to 70% after 35 days. The cobalt-60/EDTA complex appears to be dissociating and leaving uncomplexed cobalt which is readily sorbed. The dissociation seems to be rather complete in Hanford and Savannah River soil but limited in the Oak Ridge soil. The implication to waste management is that the potential for transport of cobalt by EDTA may not be as serious at all burial sites as once thought

EXAFS Determination of the Structure of Cobalt in Carbon-Supported Cobalt and Cobalt-Molybdenum Sulfide Hydrodesulfurization Catalysts.

NARCIS (Netherlands)

Koningsberger, D.C.; Bouwens, S.M.A.M.; Veen, J.A.R. van; Beer, V.H.J. de; Prins, R.

1991-01-01

The structure of the cobalt present in carbon-supported Co and Co-Mo sulfide catalysts was studied by means of X-ray absorption spectroscopy at the Co K-edge and by X-ray photoelectron spectroscopy (XPS). Thiophene hydrodesulfurization activities were used to measure the catalytic properties of

A spot test for detection of cobalt release - early experience and findings

DEFF Research Database (Denmark)

Thyssen, Jacob P; Menné, Torkil; Johansen, Jeanne D

2010-01-01

It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware that they are exposed...

A new three-dimensional cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2

Science.gov (United States)

Han, Zhangang; Tian, Aixiang; Peng, Jun; Zhai, Xueliang

2006-10-01

A three-dimensional (3D) cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2 ( 1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs.

Incentives and opportunities for reducing the cobalt content in reactor core components

International Nuclear Information System (INIS)

Ocken, H.

1985-01-01

Cobalt in core components contributes to radiation field buildup on out-of-core surfaces. Core components containing cobalt-base alloys and cobalt as an impurity are identified. The use of cobalt-free wear-resistant alloys and construction materials with lower impurity levels of cobalt is disused. It is argued that such measures are cost effective. Lower radiation fields and disposal costs will offset higher raw material costs. Component performance will not be affected. (author)

Temperature dependence of the surface tension and 0.1 MPa density for 1-Cn-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate with n=2, 4, and 6

Czech Academy of Sciences Publication Activity Database

Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav

2012-01-01

Roč. 48, MAY 2012 (2012), s. 267-275 ISSN 0021-9614 R&D Projects: GA ČR GA101/09/0010 Institutional research plan: CEZ:AV0Z20760514 Keywords : ionic liquid s * tris(pentafluoroethyl)trifluorophosphate * surface tension * group contribution method * density Subject RIV: BJ - Thermodynamics Impact factor: 2.297, year: 2012 http://www.sciencedirect.com/science/article/pii/S0021961411004770

Tetraethylammonium tris(thiocyanato-κN[tris(1H-pyrazol-1-yl-κN2methane]nickelate(II

Directory of Open Access Journals (Sweden)

Ganna Lyubartseva

2012-07-01

Full Text Available The title salt, (C8H20N[Ni(NCS3(C10H10N6], consists of a tetraethylammonium cation and an anion comprising an octahedral NiII atom surrounded by three N atoms from a tripodal tris(pyrazol-1-ylmethane ligand, and three thiocyanate ligands, each bound at the N-atom end. The ligand Ni—N distances range from 2.097 (2 to 2.127 (2 Å for the tripodal ligand and from 2.045 (2 to 2.075 (2 Å for the thiocyanate ligands. The dihedral angles between the three pyrazole rings are 59.03 (12, 53.09 (10 and 67.90 (10°.

[The mutations of the D-loop hypervariable region II and hypervariable region III of mitochondrial DNA in oral squamous cell carcinoma].

Science.gov (United States)

Wang, Yao-Zhong; Jia, Mu-Yun; Yuan, Rong-Tao; Han, Guo-Dong; Bu, Ling-Xue

2010-06-01

To investigate the frequency of mitochondrial DNA (mtDNA) D-loop hypervariable region II (HVR II) and hypervariable region III (HVR III) mutations in oral squamous cell carcinoma (OSCC) and their correlation to provide the new targets for the prevention and treatment of OSCC. The D-loop HVR II and HVR III regions of mtDNA in seven cases with OSCC tissues, matched with paracancerous tissues and normal mucosa tissues from the same case, were amplified by polymerase chain raction (PCR), then were detected by direct sequencing to find the mutantsites after the comparison of all sequencing results with the mtDNA Cambridge sequence in the GenBank database. 82 (56 species) nucleotide changes, with 51(26 species) nucleotide polymorphism, were found after the comparison of all sequencing results with the mtDNA Cambridge sequence in the GenBank database. 31(30 species) mutations, with 21 located within the HVR II and HVR III regions, were found in 3 tumor tissue samples, their paracancerous and normal mucosa tissue were found more polymorphic changes but no mutation. The mtDNA D-loop HVR II and HVR III regions mutation rate was 42.9% (3/7) in OSCC. The mtDNA D-loop HVR II and HVR III regions were highly polymorphic and mutable regions in OSCC. It suggested that the D-loop HVR II and HVR III regions of mtDNA might play a significant role in the tumorigenesis of OSCC. It may become new targets for the gene therapy of OSCC by regulating the above indexes.

Heating analysis of cobalt adjusters in reactor core

International Nuclear Information System (INIS)

Mei Qiliang; Li Kang; Fu Yaru

2011-01-01

In order to produce 60 Co source for industry and medicine applications in CANDU-6 reactor, the stainless steel adjusters were replaced with the cobalt adjusters. The cobalt rod will generate the heat when it is irradiated by neutron and γ ray. In addition, 59 Co will be activated and become 60 Co, the ray released due to 60 Co decay will be absorbed by adjusters, and then the adjusters will also generate the heat. So the heating rate of adjusters to be changed during normal operation must be studied, which will be provided as the input data for analyzing the temperature field of cobalt adjusters and the relative heat load of moderator. MCNP code was used to simulate whole core geometric configuration in detail, including reactor fuel, control rod, adjuster, coolant and moderator, and to analyze the heating rate of the stainless steel adjusters and the cobalt adjusters. The maximum heating rate of different cobalt adjuster based on above results will be provided for the steady thermal hydraulic and accident analysis, and make sure that the reactor is safe on the thermal hydraulic. (authors)

Study of thermodynamic properties of binary and ternary liquid alloys of aluminium with the elements iron, cobalt, nickel and oxygen; Etude des proprietes thermodynamiques des alliages liquides binaires et ternaires de l'aluminium avec les elements fer, cobalt, nickel et l'oxygene

Energy Technology Data Exchange (ETDEWEB)

Vachet, F [CEA Vallee du Rhone, 26-Pierrelatte (France)

1966-07-01

experimentale employee consiste a etudier le partage de l'aluminium entre les phases liquides immiscibles constituees des couples de metaux (Fe, Ag), (Co, Ag), (Ni, Ag). Les renseignements ainsi obtenus sont traduits en sections isothermes de diagramme d'equilibre de phases des systemes (Al, Fe, Ag), (Al, Co, Ag), (Al, Ni, Ag). L'etude du partage de l'argent entre le plomb et l'aluminium jointe aux travaux des differents auteurs nous permet de determiner l'activite de l'aluminium dans le metal M (fer, cobalt et nickel) presentee sous une forme analytique. Les parametres d'interactions de Wagner de l'aluminium dans le metal sont ainsi determines. Les resultats obtenus ainsi que les diagrammes d'equilibre de phases des systemes (Al, M) permettent de comparer les proprietes thermodynamiques du systems Al Fe a l'etat liquide et a l'etat solide, d'estimer les chaleurs latentes de fusion des composes intermetalliques AlCo et AlNi. L'activite a 1600 C de l'aluminium dans les alliages liquides (Al, Fe, Co), (Al, Fe, Ni), (Al, Co, Ni) est estimee a partir des proprietes thermodynamiques des systemes binaires composants en appliquant differentes methodes conduisant a des resultats en bonne concordance. L'etude des interactions aluminium-oxygene dans les metaux solvants M nous permet de proposer une explication a la forme de la ligne d'equilibre de desoxydation du fer, du cobalt et du nickel par l'aluminium et de comparer le pouvoir desoxydant de l'aluminium envers les oxydes de fer, de cobalt et de nickel. (auteur)

Oxidation of hydrogen peroxide by [Ni (cyclam)] in aqueous acidic ...

Indian Academy of Sciences (India)

Oxidation of hydrogen peroxide by tris(2,2 -bipyridine) and tris(4,4 -dimethyl-2,2 - bipyridine) complexes of osmium(III), iron(III), ruthenium(III), and nickel(III) studied in acidic and neutral aqueous media, show an inverse acid depen- dence over the pH the range 6.0–8.5.12 Kinetic mea- surements with an excess of H2O2 ...

The effect of gaseous ammonia on cobalt perrhenate

International Nuclear Information System (INIS)

Maslov, L.P.; Men'shikov, O.D.; Borisov, V.V.; Sorokin, S.I.; Krutovertsev, S.A.; Kharkevich, S.I.; Ivanova, O.M.

1994-01-01

The influence of humid air ammonia mixture on crystal pentahydrate of cobalt(2) perrhenate has been studied by the methods of PES, IR spectroscopy thermal analysis and electrophysical measurements. It is shown that with an increase in ammonia content in gaseous phase cobalt perrhenate successively transforms into diaquodiammine-, tetrammine- and μ-dioxo-bis-(tetrammine) derivatives of cobalt. Reversibility of dioxocomplex formation and a correlation between the change in electrophysical properties of crystal sample and change in ammonia content in gaseous phase are pointed out. 16 refs.; 4 figs.; 1 tab

Nitrogen induced ferromagnetism in Cobalt doped BaTiO3

Directory of Open Access Journals (Sweden)

Chandrima Mitra

2012-09-01

Full Text Available The electronic structure and magnetism of Cobalt doped BaTiO3 (BaTi1−xCoxO3 is investigated. Substitutional Nitrogen on an Oxygen site is found to play an important role in inducing net magnetic moments in the system. The presence of a Nitrogen atom as nearest neighbour to a Cobalt atom is crucial in producing spin splitting of both the Nitrogen and Cobalt states thereby introducing a net local magnetic moment. The introduction of Nitrogen is further found to enhance ferromagnetic interactions between Cobalt atoms.

Red polymer light-emitting devices based on an oxadiazole-functionalized europium(III) complex

International Nuclear Information System (INIS)

Liu, Yu; Wang, Yafei; Li, Chun; Huang, Ying; Dang, Dongfeng; Zhu, Meixiang; Zhu, Weiguo; Cao, Yong

2014-01-01

A novel tris(dibenzoylmethanato)[5-(2-(4-tert-butylbenzenyl)-5-benzenyl-1,3, 4-oxadiazole-4′)-1,10-phenanthroline]europium(III) [Eu(DBM) 3 (BuOXD-Phen)] containing an electron-transporting oxadiazole-functionalized phenanthroline ligand was synthesized and characterized. Its UV–vis absorption and photoluminescence (PL), as well as the electroluminescence (EL) in polymer light-emitting devices (PLEDs) were investigated. The double-layer PLEDs with a configuration of ITO/PEDOT:PSS (50 nm)/PVK (40 nm)/PFO:PBD (30%):Eu(DBM) 3 (BuOXD-Phen) (1–8 wt %) (80 nm)/Ba (4 nm)/Al (150 nm) were fabricated. Saturated red Eu 3+ ion emission, based on the 5 D 0 → 7 F 2 transition, is centered at a wavelength of 614 nm with a full width at half maximum (FWHM) of 10 nm. The highest external quantum efficiency (QE ext ) of 1.26% at current density of 1.65 mA cm −2 , with a maximum brightness of 568 cd m −2 at 137.8 mA cm −2 was achieved from the device at 1 wt % dopant concentration. - Highlights: • An oxadiazole-functionalized europium(III) complex of Eu(DBM) 3 (BuOXD-Phen) was presented. • The optophysical properties of Eu(DBM) 3 (BuOXD-Phen) were investigated. • Saturated red emission was observed in the PLEDs. • An external quantum efficiency of 1.26% was obtained in these devices

Analysis of radioactive cobalt

International Nuclear Information System (INIS)

1977-01-01

This is a manual published by Science and Technology Agency, Japan, which prescribes on the analysis method for radioactive cobalt which is a typical indexing nuclide among the radioactive nuclides released from nuclear facilities. Since the released cobalt is mainly discharged to coastal region together with waste water, this manual is written for samples of sea water, sea bottom sediments and marine organisms. Radioactive cobalt includes the nuclides of 57 co, 58 Co, 60 Co, etc., the manual deals with them as a whole as 60 Co of long half life. Though 60 Co analysis has become feasible comparatively simply due to scintillation or semi-conductor spectrometry, trace 60 Co analysis is performed quantitatively by co-precipitation or collection into alumina and scintillation spectrometry. However, specific collecting operation and γ-γ coincidence measurement have been required so far. This manual employs 60 Co collection by means of ion-exchange method and measurement with low background GM counting system, to analyze quantitatively and rapidly low level 60 Co. It is primarily established as the standard analyzing method for the survey by local autonomous bodies. It is divided into 4 chapters including introduction sea water, marine organisms, and sea bottom sediments. List of required reagents is added in appendix. (Wakatsuki, Y.)

Nano cobalt oxides for photocatalytic hydrogen production

KAUST Repository

Mangrulkar, Priti A.

2012-07-01

Nano structured metal oxides including TiO 2, Co 3O 4 and Fe 3O 4 have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO 2 and Fe 3O 4. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 mmol h -1 g -1 of photocatalyst for TiO 2, Co 3O 4 and Fe 3O 4 respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO 2 and the hydrogen yield of nano Fe 3O 4 was nearly four times as compared to nano Co 3O 4. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Synthesis and characterization of cobalt-manganese oxides

International Nuclear Information System (INIS)

Valencia, J.; Arias, N.P.; Giraldo, O.; Rosales-Rivera, A.

2012-01-01

Cobalt doped/un-doped manganese oxides materials were synthesized at various doping rates by soft chemical reactions, oxidation-reduction method, which allows generating a metal-mixed oxide. The synthesized materials were characterized using several techniques including chemical analysis, X-rays diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The chemical analysis confirmed the presence of cobalt in the samples. XRD patterns reveal mainly a spinel-like structure and SEM micrographs exhibited morphology with fine aggregate of particles. TGA profiles showed weight loss due to loss of water in a first step, followed by a loss of oxygen from the lattice associated with partial reduction of Mn 4+ to Mn 3+ . VSM was used to measure the magnetization as a function of the applied magnetic field at temperatures T=50 and 300 K. Different magnetic behaviors were observed when cobalt percentage changed in the samples. These behaviors are considered to be related to the size of the particles and composition of the materials. Higher coercive field and lesser magnetization were observed for the sample with higher cobalt content.

Criterion for selection the optimal physical and chemical properties of cobalt aluminate powder used in investment casting process

Directory of Open Access Journals (Sweden)

M. Zielińska

2009-07-01

Full Text Available The aim of this work was to determine physical and chemical properties of cobalt aluminate (CoAl2O4 modifiers produced by different companies and the influence of different types of modifiers on the grain size of high temperature creep resisting superalloys: Inconel 713C, René 77 and MAR-M 509.The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three different companies: Remet, Mason Color and Permedia Lublin. There were determined the grain size distribution of cobalt aluminate powder, the average diameter and morphology of powder particles, phase composition, as well as sodium and cobalt content, pH value of water suspension and the bulk density. In the next step, the ceramic moulds were made with different kind of cobalt aluminate (Mason Color, Remet, Permedia Lublin and its concentration (0, 5% in the primary slurry. The samples of stepped shape were poured in the ceramic moulds prepared earlier. The average grain size of the γ phase was determined on the stepped samples.It was established that physical and chemical properties of cobalt aluminate modifier are different up to the manufacturer. For example the modifiers manufactured by Permedia; Mason Color and Remet companies have different the average diameter of particles- 68,050d; 49,6 i 36,7μm, and also cobalt content _CoC=32,53%; 39,43% i 34,79%mass, respectively. The grain size of γ matrix of superalloys depends on the kind of used inoculant. The best grain refinement of the matrix of superalloys: Inconel 713C, René 77 and MAR-M 509 was observed in the castings modified with the use of Mason Color modifier. On the grounds of literature data and obtained results it was established that the cobalt content of cobalt aluminate influences the intensity of nucleation process during the crystallization of superalloys: Inconel 713C, René 77 i MAR-M 509.

Manda d'hajje I-II : [luuletused] / Uku Masing

Index Scriptorium Estoniae

Masing, Uku, 1909-1985

2001-01-01

Tekst eesti ja inglise k. U. Masingu lühibiograafia eesti ja inglise k. lk. 75. Sisu: Manda d'hajje I-II ; "Lennata mõtles kord muinasmaa liblikas..." = "Once a fairyland butterfly thought it would fly..." ; "Sa oled mägi, mida kardavad me karjed..." = "You are the mountain that our herds fear..." ; "Ammu tõusnud koopast, sygavalt ja kaugelt..." = "Long since risen from a cave, deep and far away..." ; "Imelik, et Sinu silmad mind ei karda..." ; "Strange that Your eyes do not fear me..." ; "Ööl järveks laiud. Ja siis äkki tõusvad üles..." = "At night You grow into a lake. From its bed..." ; "Sinu keha tõuseb minu käsivartelt..." = "Your body rises from my arms to meet me..."

Total quality management of cobalt-60 sources

International Nuclear Information System (INIS)