Showing papers on "Nickel published in 1984"
TL;DR: Partage chimique de Cd, Cu, Ni et Zn dans 3 sols et un sediment ayant precedemment recu des additions massives de metaux lourds as discussed by the authors.
Abstract: Partage chimique de Cd, Cu, Ni et Zn dans 3 sols et un sediment ayant precedemment recu des additions massives de metaux lourds
341 citations
TL;DR: In this paper, the selectivity for reduction of CO2vs. that of H2O is huge, even in pure water, in the presence of NiII(Cyclam) 2+ +.
Abstract: Co2is electroreduced efficiently to CO on a mercury cathode, in the presence [NiII(Cyclam)]2+; even in pure water, the selectivity for reduction of CO2vs. that of H2O is huge.
291 citations
BP1
TL;DR: The most active and stable hydrogen evolving cathode, based on a nickel and molybdenum combination, exhibited overvoltages of about 60 mV for over 11,000 h of continuous electrolysis in 30 w/o KOH at 500 mA cm −2 and 70°C as mentioned in this paper.
211 citations
TL;DR: Cowpeas grown in Ni-deficient nutrient solutions containing NO(3) and NH(4) developed leaflet tip necrosis, which was analogous to that produced in soybeans, and 1 micromolar NiEDTA additions prevented these symptoms.
Abstract: Soybeans (Glycine max [L.] Merr.) grown in Ni-deficient nutrient solutions accumulated toxic urea concentrations which resulted in necrosis of their leaflet tips, a characteristic of Ni deficiency. Estimates of the Ni requirement of a plant were made by using seeds produced with different initial Ni contents. When compared to soybeans grown from seeds containing 2.5 nanograms Ni, plants grown from seeds containing 13 nanograms Ni had a significantly reduced incidence of leaflet tip necrosis. Plants grown from seeds containing 160 nanograms Ni produced leaves with almost no leaflet tip necrosis symptoms. Neither Al, Cd, Sn, nor V were able to substitute for Ni.In other experiments, a small excess of EDTA was included in the nutrient solution in addition to that needed to chelate micronutrient metals. Under these conditions, nodulated nitrogen-fixing soybeans had a high incidence of leaflet tip necrosis, even when 1 micromolar NiEDTA was supplied. However, in nutrient solutions containing inorganic sources of N, 1 micromolar NiEDTA almost completely prevented leaflet tip necrosis, although no significant increase in leaf urease activity was observed. Cowpeas (Vigna unguiculata [L.] Walp) grown in Ni-deficient nutrient solutions containing NO(3) and NH(4) also developed leaflet tip necrosis, which was analogous to that produced in soybeans, and 1 micromolar NiEDTA additions prevented these symptoms.These findings further support our contention that Ni is an essential element for higher plants.
197 citations
TL;DR: In this article, photoelectron-spectroscopic studies (XPS and UPS) have been carried out to investigate electronic structure and chemical bonding in the monoselenides of nickel, manganese and cobalt.
167 citations
TL;DR: The first gas phase electronic spectrum of nickel dimer was reported in this article, and the long bond length of 2.068±0.01 eV was shown to be 2.200± 0.007 A for the ground state of Ni2, which must be of either 1Γg or 3Γu electronic symmetry species.
Abstract: We report the first gas‐phase electronic spectrum of nickel dimer. Ni2 is produced by laser vaporization of metallic nickel in the throat of a supersonic nozzle. Using resonant two photon ionization, bands previously observed in inert matrices and attributed to Ni2 are conspicuous in their absence. Further to the red, an abrupt onset of complicated spectral structure indicates rapid predissociation above 16 680 cm−1. We argue that this represents the true dissociation limit, and places D0=2.068±0.01 eV. A congested pattern of spectral features from 6000 to 9000 A confirms theoretical predictions of a large number of low‐lying electronic states in nickel dimer. Rotationally resolved bands near 8500 A are indicative of a ΔΩ=+1 transition, with Ω″=4, Ω′=5. Rotational analysis of these bands yields a bond length of 2.200±0.007 A for the ground state of Ni2, which must be of either 1Γg or 3Γu electronic symmetry species. Both the long bond length of 2.20 A and the high value of Ω″ are in agreement with theoretical predictions, and confirm that no substantial 3d participation contributes to the chemical bonding of Ni2.
166 citations
TL;DR: In this paper, nonlinear least squares curve fitting is used to analyze Ni 2p spectra obtained from various nickel-oxygen compounds and Ni/Al2O3 catalysts.
Abstract: Nonlinear least-squares curve fitting is used to analyze Ni 2p spectra obtained from various nickel-oxygen compounds and Ni/Al2O3 catalysts. Apart from NiO, which shows a characteristic discrete satellite peak 2 eV from the main 2p3/2 peak, all other spectra exhibit variable peak asymmetry assigned to multiplet splitting effects. By the use of a single extra peak to describe this asymmetry, the relative satellite/main peak intensity ratio can be used as an indication of the chemical state of nickel. Results for Ni/Al2O3 catalysts agree with reduction studies from previous work about the nature of nickel species on the surfaces of these catalysts at various nickel loadings.
165 citations
TL;DR: Mesures de l'electrodiffusion en mode stationnaire et de la diffusion anisotrope de 63 Ni dans l'etain β monocristallin par une technique de section de traceur.
Abstract: Mesures de l'electrodiffusion en mode stationnaire et de la diffusion anisotrope de 63 Ni dans l'etain β monocristallin par une technique de section de traceur
159 citations
TL;DR: Competition experiments for binding sites between nickel and other cations as well as with other complexing anions showed that /sup 63/Ni uptake was affected only by cobalt and by humic acids.
Abstract: Six strains of algae and one Euglena sp. were tested for their ability to bioaccumulate nickel. Radioactive /sup 63/Ni was used together with a microplate technique to determine the conditions for nickel removal by axenic cultures of cyanobacteria, green algae, and one euglenoid. The cyanobacteria tested were found to be more sensitive to nickel toxicity than the green algae or the Euglena sp. The concentration factor (CF) for nickel was determined under a variety of conditions and found to be in the range from 0 to 3.0 x 10/sup 3/. The effect of environmental variables on nickel uptake was examined, and a striking pH effect for biaccumulation was observed, with most of the algal strains accumulating nickel optimally at approximately pH 8.0. Competition experiments for binding sites between nickel and other cations as well as with other complexing anions, showed that /sup 63/Ni uptake was affected only by cobalt and by humic acids.
136 citations
TL;DR: In this article, transition metal interferences in the determination of selenium using the hydride generation AAS technique were investigated in a system in which the seenium hydrides is generated in pure acid solution and comes into contact with the metal ions only in a second flask.
Abstract: Transition metal interferences in the determination of selenium using the hydride generation AAS technique were investigated in a system in which the selenium hydride is generated in pure acid solution and comes into contact with the metal ions only in a second flask. All investigated elements interfere in the ionic form with selenium when they are present in sufficiently high concentrations. Whenever a precipitation of the metallic species occurs, however, capture and decomposition of the selenium hydride by the finely dispersed metal appear to be the predominant mechanism of interference. In addition, this solid-gas reaction occurs typically at considerably lower interferent concentrations than the liquid-gas reaction of the ionic species. A substantial increase in the range of interference-free determination of selenium can be achieved by increasing the acid concentration of the solution for measurement because of the increased solubility of the reduced metal in the strong acid.
135 citations
TL;DR: In this article, an amorphous zirconium-nickel phase was formed by annealing vapor deposited crystalline layers of elemental ZIRconium and nickel.
Abstract: We have formed an amorphous zirconium-nickel phase by annealing vapor deposited crystalline layers of elemental zirconium and nickel. Auger depth profiling and x-ray diffraction have been used to monitor the reaction. The thermodynamics of the process is explained in terms of a metastable free energy diagram which reflects the large negative heat of mixing between zirconium and nickel. The formation of an amorphous layer occurs via a diffusion limited reaction occurring at the zirconium-nickel interface.
TL;DR: In this paper, the authors employed several complementary experimental approaches in an attempt to gain an insight into the intimate details surrounding the nickel-titanium oxide interaction and developed a model which involves the migration of titanium-oxygen moieties onto the surface of the nickel particles during reduction in hydrogen.
TL;DR: In this article, structural and compositional data leading to the classification of 41 iron meteorites was reported, increasing the number of classified independent IR meteorites to 576. But despite the addition of 3 new irons and the reanalysis of 3 previously studied irons, the members of the set of 15 ungrouped irons having very low Ga (100 ≤ Ni ≤ 180 mg/g) and Compositional similarities to IIICD, but A80104 increases the Garden Head trio to a quartet.
TL;DR: In this article, the use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described, and the results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt using concentrated nickel sulphate solutions.
Abstract: The use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described. Comparative data indicate that the phosphinic acid is superior to analagous phosphoric and phosphonic acids in terms of cobalt-nickel selectivity and the ability to reject calcium. Important reagent properties, such as low aqueous solubility and hydrolytic stability, are discussed. The results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt from concentrated nickel sulphate solutions.
TL;DR: In this paper, the strength and nature of the binding of heavy metal ions to bacterial extracellular polymers has been investigated, and the conditional stability constants (Kt) for complexes formed between extracted Klebsiella aerogenes polymer and copper, cadmium, cobalt and nickel were determined, using a gel chromatographic technique.
TL;DR: Etude par spectrometrie a photoelectron RX and par diffusion ionique a basse energie. as discussed by the authors, et al. describe couches de passivation and leur composition chimique varient en fonction du potentiel de l'electrode and du temps d'exposition a HF
Abstract: Etude par spectrometrie a photoelectron RX et par diffusion ionique a basse energie. L'epaisseur des couches de passivation et leur composition chimique varient en fonction du potentiel de l'electrode et du temps d'exposition a HF
TL;DR: Amorphous Ni-P (Ni81P19) and Ni-B (Ni62B38) alloys have been prepared by the rapid quenching method as discussed by the authors.
Abstract: Amorphous Ni–P (Ni81P19) and Ni–B (Ni62B38) alloys have been prepared by the rapid quenching method. The untreated alloys are inactive for the hydrogenation of olefins, but successive pretreatments of the alloys with the dilute HNO3, oxygen and hydrogen bring about greater catalytic activity than that possessed by the crystalline alloys. Measurements of the ESCA spectra of the surfaces of the alloys have indicated that the alloys become active by the partial oxidation of the nickel and phosphorus or boron on the surface. Buta-1,3-diene is hydrogenated to give isomeric butenes of constant composition, and butenes isomerise rapidly to give a similar composition to that obtained on the hydrogenation of buta-1,3-diene. The hydrogenation of buta-1,3-diene is first and zeroth order with respect to the partial pressures of hydrogen and buta-1,3-diene, respectively. These results are explained by assuming that the hydrogen and the olefins are not competing for adsorption on the same sites and that hydrogen is activated on electron-deficient nickel atoms formed by electron transfer from nickel to the oxidised species.
TL;DR: In this article, the authors showed that hydrogen reduction at 700 °K of a 120-A nickel film deposited on TiO2 results in the segregation of TiOx (x close to 1) onto the nickel surface.
TL;DR: In this article, the fraction of encaged phthalocyanine decreases in the sequence CoPc-X > NiPc X > CuPcX, which is interpreted with a respective increase of the Bronsted acidity in the zeolite framework.
TL;DR: In-situ laser Raman spectra of anodic corrosion films formed on Ni and Co in 0.05M NaOH have been obtained for the first time and the composition of the surface films deduced.
Abstract: In-situ laser Raman spectra of anodic corrosion films formed on Ni and Co in 0.05M NaOH have been obtained for the first time and the composition of the surface films deduced. The Raman spectrum of the film found on Ni at about 0.6V vs. Hg/HgO corresponds closely to that of hydrated Ni/sub 2/O/sub 3/. The anodically formed film on Co at about 0.45 V appeared to consist of a mixture of CoO and Co/sub 3/O/sub 4/.
TL;DR: In this paper, the properties of superalloys at temperatures above about 6OOC were examined and it was shown that the oxide reaction product barriers are stable upon the surfaces of super-alloys by considering how these oxide scales are formed and then how they are destroyed in use.
Abstract: The oxidation, mixed gas corrosion and hot corrosion of nickel-, cobaltand iron-base superalloys at temperatures above about 6OOC are examined. It is shown that the superalloys develop resistance to corrosion by forming either alumina or chromia scales upon their surfaces. The times for which such oxide reaction product barriers are stable upon the surfaces of superalloys is discussed by first considering how these oxide scales are formed and then how they are destroyed in use. It is shown for oxidation environments that these oxide scales are degraded primarily via cracking and spalling. When mixed gas environments are encountered, the degradation is also affected by the other reactants in the gas phase. The most severe conditions are shown to be those inducing hot corrosion attack where the oxide scales are subjected to not only mixed gas conditions but also the fluxing action of molten deposits. The behavior of nickel-, cobalt-, and iron-base superalloys are compared and the effects of the various alloying elements are discussed.
TL;DR: In this paper, Tafel slopes and reaction orders for the electrodeposition of nickel from Watts type baths onto a vitreous carbon electrode have been determined by both steady state and transient methods.
TL;DR: In this article, the synthesis of σ-acetylide complexes of tungsten, iron, nickel, copper and silver has been studied and the results range from good to excellent, and the reactions are simpler to carry out than previous methods.
Abstract: Routes developed for the syntheses of σ-acetylide complexes of tungsten, iron, nickel, copper and silver include reactions of metal halide complexes with alk-1-ynes in organic amines, with copper(I) halides as catalysts, or in methanol in the presence of sodium methoxide. Yields range from good to excellent, and the reactions are generally simpler to carry out than previous methods.
TL;DR: In this paper, the results of a study on spin electronique permettant de determiner la structure, la stabilite et le comportement d'oxydation des complexes de Ni(II) and de Cu(II), avec des tetramines macrocycliques comprenant des cycles a 13-15 membres, des nombres differents d'anions imido (de 0 a 3) and des substituants phenyle, pyridyle and pyridine N-oxyde extraplanaires.
Abstract: Resultats d'etudes potentiometriques, electrochimiques, spectrochimiques et de resonance de spin electronique permettant de determiner la structure, la stabilite et le comportement d'oxydation des complexes de Ni(II) et de Cu(II) avec des tetramines macrocycliques comprenant des cycles a 13-15 membres, des nombres differents d'anions imido (de 0 a 3) et des substituants phenyle, pyridyle et pyridine N-oxyde extraplanaires
Journal Article•
TL;DR: Human nickel exposure originates from a variety of sources and is highly variable, and leaching of nickel may add to dietary intakes and to cutaneous exposures, and Occupational nickel exposure is of major significance.
Abstract: In order of abundance in the earth's crust, nickel ranks as the 24th element and has been detected in different media in all parts of the biosphere. Thus, humans are constantly exposed to this ubiquitous element, though in variable amounts. The average natural nickel exposure from food in the past has probably been somewhat, but not much, below current levels. Nickel is a useful metal, particularly in various alloys, in batteries and in nickel-plating. Nickel compounds are used especially as catalysts and pigments. In nickel-producing or nickel-using industries, about 0.2% of the work force may be exposed to considerable amounts of airborne nickel. In addition, nickel release, e.g., into cutting oils, and skin contact with nickel-containing or nickel-plated tools and other items may add to an occupational nickel hazard. Occupational exposures may lead to the retention of 100 micrograms of nickel per day. Environmental nickel levels depend particularly on natural sources, pollution from nickel-manufacturing industries and airborne particles from combustion of fossil fuels. Absorption from atmospheric nickel pollution is of minor concern. Vegetables usually contain more nickel than do other food items; high levels have been found in legumes, spinach, lettuce and nuts. Certain products, such as baking powder and cocoa powder, have been found to contain excessive amounts of nickel, perhaps related to nickel leaching during the manufacturing process. Soft drinking-water and acid beverages may dissolve nickel from pipes and containers. Leaching or corrosion processes may contribute significantly to the oral nickel intake, occasionally up to 1 mg/day. Scattered studies indicate a highly variable dietary intake of nickel, but most averages are about 200-300 micrograms/day. In addition, skin contact to a multitude of metal objects may be of significance to the large number of individuals suffering from contact dermatitis and nickel allergy. Finally, nickel alloys are often used in nails and prostheses for orthopaedic surgery, and various sources may contaminate intravenous fluids. Thus, human nickel exposure originates from a variety of sources and is highly variable. Occupational nickel exposure is of major significance, and leaching of nickel may add to dietary intakes and to cutaneous exposures. Preventive efforts should mainly be directed towards adequate control of these exposure sources.
TL;DR: In this paper, the authors investigated the cavitation erosion resistance of high purity base metals (aluminium, cobalt, chromium, copper, iron, magnesium, molybdenum, nickel, tungsten and zinc).
TL;DR: For Ni-Al alloys (containing 05 to 4 wt% Al), the depths of penetration of internal oxide precipitates on exposure to Ni/NiO packs at 800-1100°C are relatively independent of alloy composition as mentioned in this paper.