Showing papers on "Copper published in 1992"
TL;DR: In this paper, self-assembled monolayers (SAMs) derived from adsorption of nalkanethiols onto the surfaces of copper slow the oxidation of the copper surface by reaction with atmospheric dioxygen.
Abstract: Self-assembled monolayers (SAMs) derived from adsorption of n-alkanethiols onto the surfaces of copper slow the oxidation of the copper surface by reaction with atmospheric dioxygen. Angstrom-level changes in the thickness of the monolayer result in readily observable differences (by X-ray photoelectron spectroscopy, XPS) in the rates of oxidation of the copper and adsorbed thiolates. The rates of oxidation of the copper and the thiolates can be decreased by ∼50% by increasing the length of the adsorbate, and thus of the SAM, by four CH 2 units
624 citations
TL;DR: In this article, the synthesis and characterization of μ-η 2 : η 2 peroxo dinuclear copper(II) complexes which to oxyhemocyanin (or oxytyrosinase) in their physicochemical properties are presented.
Abstract: The synthesis and characterization of μ-η 2 :η 2 peroxo dinuclear copper(II) complexes which to oxyhemocyanin (or oxytyrosinase) in their physicochemical properties are presented. The low-temperature reaction of a di-μ-hydroxo copper(II) complex [Cu(HB(3,5-i-Pr 2 pz) 3 )] 2 (OH) 2 (8) with H 2 O 2 gave a μ-peroxo complex [Cu(HB(3,5-i-Pr 2 pz) 3 )] 2 (O 2 ) (6)
571 citations
TL;DR: In this paper, various copper and zinc compounds have been synthesized and characterized by electron spectroscopy (XPS) and data on the 2p 3/2 levels of Cu, Zn and S, the 1s level of O, the L 3 M 45 M 45 Auger transitions of Cu and Zn, the valence bands and the modified Auger parameters are reported.
Abstract: Various copper and zinc compounds (Cu, Zn, CuZn alloy, Cu 2 O, CuO, Cu 2 S, ZnO, ZnS) have been synthesized and characterized by electron spectroscopy (XPS). Data on the 2p 3/2 levels of Cu, Zn and S, the 1s level of O, the L 3 M 45 M 45 Auger transitions of Cu and Zn, the valence bands and the modified Auger parameters are reported. The results obtained with these reference compounds allow qualitative and quantitative interpretation of XPS analyses on mixtures of these compounds
490 citations
TL;DR: The crystal structure of the fully oxidized form of ascorbate oxidase from Zucchini has been refined at 1.90 A (1 A = 0.1 nm) resolution, using an energy-restrained least-squares refinement procedure.
426 citations
TL;DR: The interaction of Cu with Si separated by thin (50 nm) layers of tantalum, Ta2N, and a nitrogen alloy of Ta has been investigated to determine the factors that affect the success of these materials as diffusion barriers to copper.
Abstract: The interaction of Cu with Si separated by thin (50 nm) layers of tantalum, Ta2N, and a nitrogen alloy of Ta has been investigated to determine the factors that affect the success of these materials as diffusion barriers to copper. Intermixing in these films was followed as a function of annealing temperature by in situ resistance measurements, Rutherford backscattering spectra, scanning electron microscopy, and cross‐section transmission electron microscopy. Ta prevents Cu‐silicon interaction up to 550 °C for 30 min in flowing purified He. At higher temperatures, copper penetration results in the formation of η‘‐Cu3Si precipitates at the Ta‐Si interface. Local defect sites appear on the surface of the sample in the early stages of this reaction. The Ta subsequently reacts with the substrate at 650 °C to form a planar hexagonal‐TaSi2 layer. Ta silicide formation, which does not occur until 700 °C in a Ta‐Si binary reaction couple, is accelerated by the presence of Cu. Nitrogen‐alloyed Ta is a very similar...
422 citations
15 Dec 1992-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: A Taylor-type model for large deformation polycrystalline plasticity is formulated and evaluated by comparing the predictions for the evolution of crystallographic texture and the stress-strain response in simple compression and tension, plane strain compression, and simple shear of initially ‘isotropic’ OFHC copper against corresponding experiments, and finite element simulations of these experiments using a multitude of single crystals with accounting for the satisfaction of both compatibility and equilibrium as discussed by the authors.
Abstract: A Taylor-type model for large deformation polycrystalline plasticity is formulated and evaluated by comparing the predictions for the evolution of crystallographic texture and the stress-strain response in simple compression and tension, plane strain compression, and simple shear of initially ‘isotropic’ OFHC copper against ( a ) corresponding experiments, and ( b ) finite element simulations of these experiments using a multitude of single crystals with accounting for the satisfaction of both compatibility and equilibrium. Our experiments and calculations show that the Taylor-type model is in reasonable first-order agreement with the experiments for the evolution of texture and the overall stress-strain response of single-phase copper. The results of the finite element calculations are in much better agreement with experiments, but at a substantially higher computational expense.
388 citations
TL;DR: In this paper, a mechanism for the oxidation of carbohydrates at copper electrodes is proposed, which includes the formation of complex species between the carbohydrates and the copper, and the extent of this interaction is measured by the decrease in peak height and electrochemical charge under the Cu(II) formation wave, and is sugar dependent.
306 citations
TL;DR: In this paper, the interaction of nitric oxide with copper ZSM5 zeolites at room temperature has been studied by EPR and FT-IR spectroscopy in the aim of investigating the surface intermediates involved in the decomposition of NO to N2 and O2.
304 citations
01 Jan 1992
258 citations
TL;DR: In this article, the mechanisms by which chloride ion and polyethylene glycol, two of the common additives in commercial acid copper electroplating baths, influence the cathodic deposition of copper have been investigated using potential sweep and potential step techniques as well as laser Raman spectroscopy.
240 citations
TL;DR: In this article, an X-ray photoelectron spectroscopy analysis of certain standard materials from the system CuOSH was carried out, which is important in the study of corrosion products formed on copper in aqueous or atmospheric sulfurbearing environments.
TL;DR: In this paper, the effect of pH on adsorption of Cd, Cu, Ni, Pb, and Zn was investigated under different cropping systems, and plots of metal adaption vs. pH (unadjusted) were generated for 24 soils, 12 from each of two long-term cropping system.
Abstract: The effect of pH on adsorption of Cd, Cu, Ni, Pb, and Zn by soils under different cropping systems was investigated. Plots of metal adsorption vs. pH (unadjusted) were generated for 24 soils, 12 from each of two long-term cropping systems. Two soils, one from each site, were selected to study the me
TL;DR: A new type of multiple concentration test has been used to analyse the genetic control of copper tolerance in Silene vulgaris and provisional results indicate that the occurrence of any tolerance, relative to a non-tolerant reference population from uncontaminated soil, is governed by a single major gene.
Abstract: The genetic control of heavy metal tolerance in higher plants is poorly understood, possibly in part because of several inherent properties of tolerance tests and tolerance measures. In this study we compared different methods of testing for copper tolerance in Silene vulgaris. A new type of multiple concentration test has been used to analyse the genetic control of copper tolerance in this species. Provisional results indicate that the occurrence of any tolerance, relative to a non-tolerant reference population from uncontaminated soil, is governed by a single major gene. The level of tolerance, however, seems to be controlled by a number of modifiers, which are completely hypostatic to the major gene. This model agrees with that proposed for Mimulus guttatus by Macnair (1983).
01 Mar 1992
TL;DR: In this paper, a double layer is formed on gold, for the UHV-prepared layer and evidence is found for the coordination of both amino and carboxyl groups to the surface, in addition to chemisorption through the thiol group.
Abstract: l -Cysteine adsorbates and multilayer films on gold and copper surfaces have been investigated by X-ray photoelectron spectroscopy. Both adsorbates, prepared by vapor deposition in UHV and prepared from solution, strongly indicate a dissociative chemisorption through the thiol group (−SH) on the metal surface. We suggest that an organized double layer is formed on gold, for the UHV-prepared layer. In the case of copper, evidence is found for the coordination of both amino and carboxyl groups to the surface, in addition to chemisorption through the thiol group. When l -cysteine is adsorbed from solution on copper, all of the thiol groups interact with copper ions, even in a 25-A-thick layer. This indicates copper ion diffusion and copper complex formation through the entire layer.
TL;DR: In this paper, the X-ray diffraction patterns of the thin films were investigated before and after the films had been annealed in a nitrogen atmosphere, and the results indicated that the films are p type.
Patent•
27 Feb 1992
TL;DR: In this article, an electroless plating bath containing a water soluble tin and/or lead salt, an acid capable of dissolving the salts, and a complexing agent is described.
Abstract: The invention provides a process for electroless plating tin, lead or tin-lead alloy on copper or copper alloy using an electroless plating bath containing a water soluble tin and/or lead salt, an acid capable of dissolving the salts, and a complexing agent. The tin and/or lead content in the bath is maintained high enough to chemically deposit thick films by replenishing the tin and/or lead salt in proportion to an increase in concentration of copper ion dissolving out in the bath. Also provided is an electroless tin, lead or tin-lead alloy plating process in which a water soluble copper salt is added to a fresh bath.
TL;DR: Two copper phosphonates, Cu(O 3 PCH 3 ) and H 2 O, have been synthesized and their structures determined as mentioned in this paper, and they have been shown to be monoclinic.
Abstract: Two copper phosphonates, Cu(O 3 PCH 3 ).H 2 O and Cu(O 3 PC 6 H 5 ).H 2 O, have been synthesized and their structures determined. Cu(O 3 PCH 3 ).H 2 O is monoclinic: space group P2 1 /c, a=8.495 (4) A, b=7.580 (4) A, c=7.289 (4) A, β=90.08 (4) o , Z=4, V=469.4 (7) A 3 . Refinement with 683 observed reflections for which 1 ≥3σ(I) gave R=0.030 and R w =0.041
TL;DR: In this article, a methodology of evaluating phytotoxicity criteria for metals, when sewage sludges are applied on cropland, is presented. But the analysis is based on data available in technical literature and fundamental principles of soil fertility and plant nutriton.
Abstract: This study illustrates a methodology of evaluating phytotoxicity criteria for metals, when sewage sludges are applied on cropland. The analyses are based on data available in technical literature and fundamental principles of soil fertility and plant nutriton. First, data from laboratory experiments, where plants were grown in media treated with only one metal element, were used to develop an empirical cause-and-effect relationship between metal concentration in plant tissue and growth retardation of plants []
TL;DR: The phytochelatin content of the root apex can be used as a quantitative tolerance-independent measure of the degree of toxicity experienced by the plant.
Abstract: Plants from nontolerant and copper-tolerant populations of Silene vulgaris both produce phytochelatins upon exposure to copper. The threshold copper concentration for induction of phytochelatin and the copper concentration at which maximum phytochelatin contents occurs increase proportionally with the level of tolerance to copper. When exposed to their own highest no-effect concentration or 50%-effect concentration of copper for root growth, tolerant and nontolerant plants exhibit equal phytochelatin contents in the root apex, which is the primary copper target. This also holds for distinctly tolerant nonsegregating F3 families, derived from a single cross of a nontolerant plant to a tolerant one. Therefore, the phytochelatin content of the root apex can be used as a quantitative tolerance-independent measure of the degree of toxicity experienced by the plant. Differential copper tolerance in S. vulgaris does not appear to rely on differential phytochelatin production.
TL;DR: The digestive gland of cephalopods (carnivorous molluscs whose age can be easily calculated with great accuracy) would seem to constitute a good potential indicator of heavy metal concentrations in the marine environment.
Abstract: The concentrations of 11 heavy metals (Ag, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) were measured in the tissues (digestive gland, branchial hearts, gills, digestive tract, kidney, genital tract, muscle, skin, shell) of the two cephalopods Eledone cirrhosa (d'Orb.) and Sepia officinalis (L.) collected from the French coast of the English Channel in October 1987. The tissues of both species displayed a similar pattern of heavy-metal accumulation: the digestive gland, branchial hearts and kidney were the major sites of concentration for all 11 metals; the digestive gland accumulated silver, cadmium, cobalt, copper, iron, lead and zinc, the branchial hearts high concentrations of copper, nickel and vanadium, and the kidney high concentrations of manganese, nickel and lead. The digestive gland, which constituted 6 to 10% of the whole-animal tissue, contained >80% of the total body burden of Ag, Cd and Co and from 40 to 80% of the total body burden of the other metals. The ratios between heavy metal concentrations in the digestive gland and those in the muscle separated the elements into three groups, those with a ratio ≤10 (Cr, Mn, Ni, Pb, V, Zn), those with a ratio >10 to <50 (Co, Cu, Fe), and those with a ratio ≥50 (Ag, Cd). The digestive gland of cephalopods (carnivorous molluscs whose age can be easily calculated with great accuracy) would seem to constitute a good potential indicator of heavy metal concentrations in the marine environment.
TL;DR: The specific adsorption of anions in acid electrolytes containing sulfuric and hydrochloric acids was found to have a strongly inhibiting effect on the rate of methanol electro-oxidation on both the (111) and (100) surfaces of platinum as discussed by the authors.
TL;DR: New nomenclature is used to classify the copper sites more precisely with respect to their structural features and spectroscopic properties along with their definitions.
Abstract: Publisher Summary Copper is an essential component for living systems, although excess intake causes symptoms, such as Wilson's disease. Numerous copper-containing proteins are now known and can be categorized based on their functions that are as follows: (1) electron-transfer carrier: plastocyanin, azurin, and pseudoazurin, (2) dioxygen carrier: hemocyanin, (3) oxygenation: tyrosinase, dopamine β -hydroxylase, phenylalanine hydroxylase, and peptidylglycine -amidating monooxygenase, (4) oxidation: galactose oxidase, amine oxidase, and ascorbate oxidase, (5) reduction: nitrite reductase and nitrous reductase, (6) disproportionation: superoxide dismutase, and (7) unknown: stellacyanin, umecyanin, and cucumber basic blue copper protein. Based on the spectroscopic properties, mainly electron paramagnetic resonance (EPR), the active sites of copper proteins have been classified into three groups, types I, II, and III. In this review, new nomenclature is used to classify the copper sites more precisely with respect to their structural features and spectroscopic properties along with their definitions. The synthesis, characterization, and reactivity of low-molecular-weight copper complexes with artificial ligands, designed to mimic structurally the copper sites in proteins, have been a major topic in current bioinorganic chemistry. The unusual spectroscopic properties of type I copper have been particularly fascinating to many inorganic chemists. Hemocyanin (Hc) is a widely occurring oxygen transport protein in invertebrates, arthropods, and mollusks. Hc contains type III copper that binds dioxygen reversibly as peroxide.
TL;DR: In this article, the effect of the preparation method on the catalytic behavior of copper/zirconia catalysts for the synthesis of methanol from carbon dioxide has been investigated.
Abstract: The effect of the preparation method on the catalytic behaviour of copper/zirconia catalysts for the synthesis of methanol from carbon dioxide has been investigated. Conventional precipitation, ion exchange and impregnation methods have been used in addition to the methods of deposition precipitation and co-precipitation in the presence of reducing agents. Precipitation reactions at constant pH were found to be an interesting route for the preparation of highly active and selective Cu/ZrO2 catalysts. Efficient catalysts were found to consist of microcrystalline copper particles which are stabilised through interaction with an amorphous zirconia matrix, resulting in a high interfacial area. The determination of the copper surface area by nitrous oxide titration revealed that the methanol synthesis activity did not exhibit a general correlation with the specific copper surface area of the catalysts; such a correlation is found only within families of similarly prepared catalysts. The influence of the residence time on the relative selectivity γ (CH3OH/CO ) was investigated in the temperature range 473 to 533 K at a pressure of 1.7 MPa. The results indicated that methanol and desorbing carbon monoxide are probably formed from carbon dioxide via parallel reaction pathways. The activation energies calculated from these results wereEA = 47.9±1.4 kJ mol−1 for the methanol synthesis reaction andEA = 93.2±2.9 kJ mol−1 for carbon monoxide formation.
TL;DR: In this paper, thermal diffusivity, electrical resistivity, density, and heat capacity have been measured for Cu6Sn5, Cu3Sn, and Ni3Sn4, and the apparent Lorenz number for comparison with the theoretical value was found.
Abstract: The thermal diffusivity, electrical resistivity, density, and heat capacity have been measured for Cu6Sn5, Cu3Sn, and Ni3Sn4. These properties were used to evaluate the apparent Lorenz number for comparison with the theoretical value. Acceptable agreement was found.
TL;DR: Observations indicate that the preventive effect of histidine on the copper-catalyzed peroxidation of LDL is not simply mediated by chelating free copper ions in aqueous phase, and evidence that copper bound to LDL particle still has a redox potential was provided by the observed increase in TBARS content during incubation of LDL-Cu complexes in the absence of free Copper ions.
TL;DR: In this paper, a Clark-type oxygen electrode and spectrophotometric methods were used to detect the oxidation of catechol by molecular oxygen in the presence of catalytic amounts of copper(II) ions.
Abstract: The oxidation of catechol by molecular oxygen in the presence of catalytic amounts of copper(II) ions has been followed by use of a Clark-type oxygen electrode and spectrophotometric methods at 25.0 o C and with the ionic strength maintained at 1.0 M (KNO 3 )
TL;DR: The results suggest that the deleterious effects of Copper ions in vivo are diminished by biochemical chelators, especially glutathione, which probably has a major role in moderating the toxicological effects of copper.
TL;DR: In this paper, the 2p absorption spectra of divalent and monovalent copper minerals are presented, and the differences in the spectra can be used to distinguish between the two oxidation states, which has been applied to copper sulphide tetrahedrite complexes.