Search results for "cobalt"

Erratum to “Beta decay half-lives of neutron rich Ti–Co isotopes around N=40” [Nucl. Phys. A 660 (1999) 3–19]

2000

Abstract The neutron-rich 57−59 Ti, 59−62 V, 61−64 Cr, 63−66 Mn, 65−68 Fe, 67−70 Co have been produced at GANIL via interactions of a 60.4 MeV/u 86 Kr 34+ with a 58 Ni target. They have been separated by the doubly achromatic spectrometer LISE3. Beta-decay half-lives have been determined for all produced nuclei, and subsequent γ -rays have been observed for the most efficiently produced nuclei. The measured half-lives of vanadium and chromium isotopes are compared to QRPA calculations using ground states deformations from the FRDM or ETFSI models. In an astrophysical context, the short half-lives of 58 Ti and 64 Cr indicate that these nuclei are potential r-process progenitors, after β -dec…

Metal complexes of the carbonic anhydrase inhibitor methazolamide (Hmacm). Crystal structure of the Zn(macm)2 (NH3)2. Anticonvulsant properties of th…

1995

Complexes of Co(II), Cu(II), and Zn(II) with deprotonated methazolamide and ammonia are synthesized and characterized. The complex Zn(macm)2(NH3)2 crystallizes in the monoclinic C2/c space group with a = 13.468(1), b = 6.759(1), c = 23.014(2) A, beta = 90.27(1), and Z = 4. The structure was refined to R = 0.049 (Rw = 0.053). The Zn(II) ion is coordinated to two deprotonated sulfonamido nitrogen atoms of the macm- ligand and two nitrogen atoms of the ammonia ligands in a distorted tetrahedron. The Zn(macm)2(NH3)2 complex is shown to be a simple model for the methazolamide inhibition of CA. EHMO calculations applied to fractional coordinates of the Zn(macm)2(NH3)2 complex indicate that the at…

SnCo nanowire array as negative electrode for lithium-ion batteries

2011

Abstract Amorphous SnCo alloy nanowires (NWs) grown inside the channels of polycarbonate membranes by potentiostatic codeposition of the two metals (SnCo- PM ) were tested vs. Li by repeated galvanostatic cycles in ethylene carbonate-dimethylcarbonate – LiPF 6 for use as negative electrode in lithium ion batteries. These SnCo electrodes delivered an almost constant capacity value, near to the theoretical for an atomic ratio Li/Sn of 4.4 over more than 35 lithiation–delithiation cycles at 1 C. SEM images of fresh and cycled electrodes showed that nanowires remain partially intact after repeated lithiation–delithiation cycles; indeed, several wires expanded and became porous. Results of amorp…

X-ray and dielectric characterization of Co doped tetragonal BaTiO3 ceramics

2016

ABSTRACTThe crystal structure modifications of BaTiO3 induced by cobalt doping were studied. The polycrystalline (1 − x)BaTiO3 + xCo2O3 samples, with x ≤ 10 wt.%, were prepared by high temperature sintering conventional method. According to X-ray phase and structural characterization, performed by full-profile Rietveld refinement technique, all synthesized samples showed tetragonal symmetry perovskite structure with minor amount of parasitic phases. Pure single-phase composition has been detected only in the low level of doping BaTiO3. It was indicated that substitution of Co for the Ti sites in the (1 − x)BaTiO3 + xCo2O3 series led to decrease of tetragonality (c/a) of the BaTiO3 perovskit…

EPR and Magnetic Susceptibility Studies of Cobalt(II)- and Nickel(II)-Substituted Azurins from Pseudomonas aeruginosa. Electronic Structure of the Ac…

1996

The electronic properties of cobalt(II)- and nickel(II)-substituted azurins from Pseudomonas aeruginosa have been investigated. EPR data for the cobalt derivative and paramagnetic susceptibility data for the nickel derivative are reported. The EPR spectrum of Co(II)−azurin shows the typical pattern of a Kramers' doublet (±1/2) associated with an S = 3/2 ground state in a distorted axial symmetry environment. The temperature dependence of the EPR intensities shows that this Kramers' doublet is the excited doublet and, therefore, that the corresponding zero-field splitting parameter D is negative (∼−3.5 cm-1). The mean g value is equal to 2.3. Nickel(II) azurin exhibits an effective magnetic …

Low-temperature optical spectroscopy of cobalt in Cu,Co superoxide dismutase: a structural dynamics study of the solvent-unaccessible metal site.

1995

The temperature dependence (300 to 10 K) of the electronic absorption spectra of the cobalt chromophore in bovine superoxide dismutase (SOD) having the native Zn(II) ion selectivity replaced by Co(II) has been investigated in four different derivatives: Cu(II),Co(II) SOD, N3(-)-Cu(II), Co(II) SOD, Cu(I),Co(II) SOD, and E,Co(II) SOD in which the copper ion has been selectively removed. In the Cu(II),Co(II) SOD, the cobalt spectrum is characterized at room temperature by three bands centered at 18,472, 17,670, and 16,793 cm-1; the low-frequency band is split, at low temperatures, into two components, indicating a lower symmetry contribution to a predominantly tetrahedral crystal field. Additi…

Solid-State Synthesis of “Bamboo-Like” and Straight Carbon Nanotubes by Thermolysis of Hexa-peri-hexabenzocoronene–Cobalt Complexes

2006

Cobalt Corroles with Bis‐Ammonia or Mono‐DMSO Axial Ligands. Electrochemical, Spectroscopic Characterizations and Ligand Binding Properties

2018

International audience; Four bis-ammonia ligated cobalt corroles and four mono-DMSO ligated cobalt corroles with different mesoaryl substituents on the macrocycle (A 2 Band A 3-corroles) were synthesized and investigated as to their electrochemical and spec-troscopic properties under different solution conditions. The complexation energies of the investigated cobalt corroles were theoretically calculated to illustrate the propensity of the cobalt center for pentacoordination or hexa-coordination with various axial ligands (DMSO, CO, py and NH 3). The structure of one hexacoordinate bis-NH 3 cobalt corrole complex was also determined by X-ray diffraction.

Density functional theory based screening of ternary alkali-transition metal borohydrides: a computational material design project.

2009

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K M1; and 1 alkali, alkaline earth or 3d / 4d transition metal atom M2 plus two to five BH4  groups, i.e., M1M2BH42‐5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1Al/ Mn/ FeBH44, Li/ NaZnBH43, and Na/ KNi/ CoBH43 alloys are …

Dehydrogenation versus Oxygenation in Two-Electron and Four-Electron Reduction of Dioxygen by 9-Alkyl-10-methyl-9,10-dihydroacridines Catalyzed by Mo…

2004

Dehydrogenation of 10-methyl-9,10-dihydroacridine (AcrH(2)) by dioxygen (O(2)) proceeds efficiently, accompanied by the two-electron and four-electron reduction of O(2) to produce H(2)O(2) and H(2)O, which are effectively catalyzed by monomeric cobalt porphyrins and cofacial dicobalt porphyrins in the presence of perchloric acid (HClO(4)) in acetonitrile (MeCN) and benzonitrile (PhCN), respectively. The cobalt porphyrin catalyzed two-electron reduction of O(2) also occurs efficiently by 9-alkyl-10-methyl-9,10-dihydroacridines (AcrHR; R = Me, Et, and CH(2)COOEt) to yield 9-alkyl-10-methylacridinium ion (AcrR+) and H(2)O(2). In the case of R = Bu(t) and CMe(2)COOMe, however, the catalytic two…