Nickel layers on indium arsenide

We report here on the preparation and characterization of InAs substrates for in situ deposition of ferromagnetic contacts, a necessary precursor for semiconductor devices based on spin injection. InAs has been grown on InAs(111)A and (100) substrates by molecular-beam epitaxy and then metalized in situ in order to better understand the mechanisms that inhibit spin injection into a semiconductor. Initial x-ray characterization of the samples indicate the presence of nickel arsenides and indium–nickel compounds forming during deposition at temperatures above room temperature. Several temperature ranges have been investigated in order to determine the effect on nickel-arsenide formation. The presence of such compounds at the interface could greatly reduce the spin-injection efficiency and help elucidate previous unsuccessful attempts at measuring spin injection into InAs

Several new catalysts for reduction of oxygen in fuel cells

Test results prove nickel carbide or nitride, nickel-cobalt carbide, titanium carbide or nitride, and intermetallic compounds of the transition or noble metals to be efficient electrocatalysts for oxygen reduction in alkaline electrolytes in low temperature fuel cells

Method of producing nickel electrode

A large capacity nickel electrode is provided in which the charging efficiency and discharge utilization coefficient are improved in comparison to nickel electrodes which are produced by the conventional method. Nickel electrodes retaining nickel active material or nickel active material and cobalt compounds on a porous nickel substrate are immersed in a cobalt sulfate aqueous solution whose pH is adjusted in the range of 3.5 to 6.0, followed by crystallization of the hydroxide or oxide by pyrolysis or immersion in alkali, thereby coating the surface of the nickel active material with cobalt crystals and simultaneously promoting alloying of the nickel-cobalt

Molecular mechanisms of nickel carcinogenesis: nickel binding to histone H4 and Cap43 protein

The carcinogenicity of nickel compounds has been confirmed and corroborated by numerous epidemiological studies in humans and carcinogenesis bioassays in animals. We also found that an excellent tumour marker recently discovered and specifically induced by nickel, Cap43 protein, has a new mono-histidinic motif consisting of ten amino acids TRSRSHTSEG repeated three times in the C-terminus which is able to bind several metal ions in a cooperative way

Synthesis, characterization and ethylene polymerization behaviour of binuclear nickel halides bearing 4,5,9,10-tetra(arylimino)pyrenylidenes

Pyrene-4,5,9,10-tetraone was prepared via the oxidation of pyrene, and reacted with various anilines to afford a series of 4,5,9,10-tetra(arylimino)pyrenylidene derivatives (L1–L4). The tetraimino-pyrene compounds L1 and L2 were reacted with two equivalents of (DME)NiBr₂ in CH₂Cl₂ to afford the corresponding dinickel bromide complexes (Ni1 and Ni2). The organic compounds were fully characterized, whilst the bi-metallic complexes were characterized by FT-IR spectra and elemental analysis. The molecular structures of representative organic and nickel compounds were confirmed by single-crystal X-ray diffraction studies. These nickel complexes exhibited high activities towards ethylene polymerization in the presence of either MAO or Me₂AlCl, maintaining a high activity over a prolonged period (longer than previously reported dinickel complex pre-catalysts). The polyethylene obtained was characterized by GPC, DSC and FT-IR spectroscopy and was found to possess branched features

Beneficial influence of nanocarbon on the aryliminopyridylnickel chloride catalyzed ethylene polymerization

A series of 1-aryliminoethylpyridine ligands (L1―L3) was synthesized by condensation of 2-acetylpyridine with 1-aminonaphthalene, 2-aminoanthracene or 1-aminopyrene, respectively. Reaction with nickel dichloride afforded the corresponding nickel (II) chloride complexes (Ni1–Ni3). All compounds were fully characterized and the molecular structures of Ni1 and Ni3 are reported. Upon activation with methylaluminoxane (MAO), all nickel complexes exhibit high activities for ethylene polymerization, producing waxes of low molecular weight and narrow polydispersity. The presence of multi-walled carbon nanotubes (MWCNTs) or few layer graphene (FLG) in the catalytic medium can lead to an increase of productivity associated to a modification of the polymer structure

2-{2,6-Bis[bis(4-fluorophenyl)methyl]-4-chlorophenylimino} -3-aryliminobutylnickel(II) bromide complexes: Synthesis, characterization, and investigation of their catalytic behavior

The series of 2-{2,6-bis[di(4-fluorophenyl)methyl]-4-chlorophenylimino}-3- aryliminobutane derivatives (L1-L5) and their nickel(II) dibromide complexes (Ni1-Ni5) were synthesized, and all organic compounds were fully characterized by the Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy and by elemental analysis, while the nickel complexes were characterized by FT-IR spectroscopy, elemental analysis, as well as by single-crystal X-ray diffraction for two representative examples, namely Ni1 and Ni4. A distorted tetrahedral geometry was observed for these four-coordinate nickel complexes. Upon the activation with either Methylaluminoxane or modified methylaluminoxane as co-catalyst, all nickel complex precatalysts showed very high activity toward ethylene polymerization with activities of up to 10 7 g(PE)·mol -1 (Ni)·h -1 , and afforded highly branched polyethylene with a bimodal distribution. © 2014 Elsevier B.V

Nickel binding sites in histone proteins

Nickel compounds are well known as human carcinogens, though the molecular events that are responsible for this are not well understood. It has been proposed that a crucial element in the mechanism of carcinogenesis is the binding of Ni(II) ions within the cell nucleus. It is known that DNA polymer binds Ni(II) only weakly, leaving the proteins of the cell nucleus as the likely Ni(II) targets. Being histone proteins the most abundant among them, they can be considered the primary sites for nickel binding. Here we describe the interactions of nickel with histone H4, core tetramer (H3-H4)2 and several peptide fragments which have been selected as the candidates for specific binding sites in the histone octamer. The results allowed us to propose several mechanisms of nickel induced damage resulting from metal coordination, including structural changes of histone proteins, as well as nucleobase oxidation and sequence-specific histone hydrolysis. The aim of the present work is to provide a comprehensive overview of literature dealing with nickel coordination to histone proteins and its link with nickel involvement in toxicity and carcinogenicity

Catalytic pyrolysis of impregnated biomass

An innovative way of catalysis was tested for its potential to reduce the amount of hydrocarbons produced during pyrolysis of oak wood. The experiments were carried out in a horizontal tubular reactor fed with a controlled flowrate of Nitrogen and equipped with accessories to collect char, liquid and gaseous products. Pyrolysis was done at 700°C with a Nickel or Iron based catalyst introduced inside the wood matrix by wet impregnation. In addition, a blank run was undertaken in which the biomass was acid-washed to determine the impact of demineralization. The influences of the catalyst nature and of the catalyst content in the wood on the reduction of condensable organic compounds were determined. Depending on the experimental conditions, the liquid yield decreases from 7.3% to 31.9% when metals are inserted in the wood. Hydrocarbons are cracked into gaseous components and the concentration of H2 has a significant increase. These results showed that biomass impregnated with Nickel and Iron is a promising way to reduce condensable organic compounds produced during pyrolysis. (Résumé d'auteur