Showing papers on "Copper published in 2003"
TL;DR: There is a marked resemblance in superconducting properties between the present material and high-Tc copper oxides, suggesting that the two systems have similar underlying physics.
Abstract: Since the discovery of high-transition-temperature (high-T(c)) superconductivity in layered copper oxides, many researchers have searched for similar behaviour in other layered metal oxides involving 3d-transition metals, such as cobalt and nickel. Such attempts have so far failed, with the result that the copper oxide layer is thought to be essential for superconductivity. Here we report that Na(x)CoO2*yH2O (x approximately 0.35, y approximately 1.3) is a superconductor with a T(c) of about 5 K. This compound consists of two-dimensional CoO2 layers separated by a thick insulating layer of Na+ ions and H2O molecules. There is a marked resemblance in superconducting properties between the present material and high-T(c) copper oxides, suggesting that the two systems have similar underlying physics.
1,495 citations
TL;DR: In biological systems, copper homeostasis has been characterized at the molecular level and is coordinated by several proteins such as glutathione, metallothionein, Cu-transporting P-type ATPases, Menkes and Wilson proteins and by cytoplasmic transport proteins called copper chaperones to ensure that it is delivered to specific subcellular compartments and thereby to copper-requiring proteins.
755 citations
TL;DR: Escherichia coli is equipped with multiple systems to ensure safe copper handling under varying environmental conditions, but pathways of copper uptake and intracellular copper handling are still not identified in E. coli.
Abstract: Escherichia coli is equipped with multiple systems to ensure safe copper handling under varying environmental conditions. The Cu(I)-translocating P-type ATPase CopA, the central component in copper homeostasis, is responsible for removing excess Cu(I) from the cytoplasm. The multi-copper oxidase CueO and the multi-component copper transport system CusCFBA appear to safeguard the periplasmic space from copper-induced toxicity. Some strains of E. coli can survive in copper-rich environments that would normally overwhelm the chromosomally encoded copper homeostatic systems. Such strains possess additional plasmid-encoded genes that confer copper resistance. The pco determinant encodes genes that detoxify copper in the periplasm, although the mechanism is still unknown. Genes involved in copper homeostasis are regulated by MerR-like activators responsive to cytoplasmic Cu(I) or two-component systems sensing periplasmic Cu(I). Pathways of copper uptake and intracellular copper handling are still not identified in E. coli.
675 citations
TL;DR: The thermodynamics of copper ion/tree fern system indicates spontaneous and endothermic nature of the process and various thermodynamic parameters, such as Delta G(0), Delta H(0) and Delta S(0, have been calculated.
646 citations
TL;DR: A review of characteristics of copper slag as well as various processes such as pyro, hydro and combination of pyro-hydrometallurgical methods for metal recovery and preparation of value added products from copper slags is given in this paper.
Abstract: Copper slag, which is produced during pyrometallurgical production of copper from copper ores contains materials like iron, alumina, calcium oxide, silica etc. For every tonne of metal production about 2.2 ton of slag is generated. Dumping or disposal of such huge quantities of slag cause environmental and space problems. During the past two decades attempts have been made by several investigators and copper producing units all over the world to explore the possible utilisation of copper slag. The favourable physico-mechanical characteristics of copper slag can be utilised to make the products like cement, fill, ballast, abrasive, aggregate, roofing granules, glass, tiles etc. apart from recovering the valuable metals by various extractive metallurgical routes. This paper gives a review of characteristics of copper slag as well as various processes such as pyro, hydro and combination of pyro-hydrometallurgical methods for metal recovery and preparation of value added products from copper slag.
600 citations
TL;DR: In this article, the authors describe a nanometer-scale switch that uses a copper sulfide film and demonstrate its performance, which is a chalcogenide semiconductor sandwiched between copper and metal electrodes.
Abstract: We describe a nanometer-scale switch that uses a copper sulfide film and demonstrate its performance. The switch consists of a copper sulfide film, which is a chalcogenide semiconductor, sandwiched between copper and metal electrodes. Applying a positive or negative voltage to the metal electrode can repeatedly switch its conductance in under 100 μs. Each state can persist without a power supply for months, demonstrating the feasibility of nonvolatile memory with its nanometer scale. While biasing voltages, copper ions can migrate in copper sulfide film and can play an important role in switching.
513 citations
TL;DR: In this paper, a method to deposit Cu metal onto surface-attached DNA, forming nanowire-like structures that are ∼3 nm tall, was developed, and the resulting nanostructures have been observed and characterized by atomic force microscopy.
Abstract: We have developed a method to deposit Cu metal onto surface-attached DNA, forming nanowirelike structures that are ∼3 nm tall. DNA is first aligned on a silicon surface and then treated with aqueous Cu(NO3)2. After the copper(II) has electrostatically associated with the DNA, it is reduced by ascorbic acid to form a metallic copper sheath around the DNA. The resulting nanostructures have been observed and characterized by atomic force microscopy. A more complete coating can be obtained by repeating the Cu(II) and ascorbic acid treatment. Control experiments involving treatments with aqueous solutions containing either NO3- or the divalent cation Mg2+ show no change in DNA height upon ascorbic acid exposure. These experiments indicate that copper nanowires, which may be valuable as interconnects in nanoscale integrated circuitry, can be readily generated from DNA molecules on surfaces.
452 citations
TL;DR: In this paper, the cold-gas dynamic-spray process is analyzed by numerical modeling of the impact between a single spherical feed-powder particle and a semi-infinite substrate and the results obtained indicate that the two main factors contributing to the observed higher deposition efficiency in the case of copper deposition on aluminum are larger particle/substrate interfacial area and higher contact pressures.
444 citations
TL;DR: In this paper, a commercially available activated carbon was modified with 1.0 M citric acid to improve copper ion adsorption from aqueous solutions and the results showed that the surface modification reduced the specific surface area by 34% and point of zero charge (pHpzc) of the carbon by 0.5 units.
354 citations
TL;DR: In this article, Aminated polyacrylonitrile fibers (APANFs) were used as an adsorbent to remove lead and copper ions from aqueous solutions and it was found that the zero ζ potential point of the APANFs was at about pH = 8.1, in contrast with that of the PANFs at pH = 3.6.
Abstract: Aminated polyacrylonitrile fibers (APANFs) were prepared through the reaction of polyacrylonitrile fibers (PANFs) with diethylenetriamine in a solution and were used as an adsorbent to remove lead and copper ions from aqueous solutions. It was found that the zero ζ potential point of the APANFs was at about pH = 8.1, in contrast with that of the PANFs at pH = 3.6, and the APANFs had significantly higher adsorption capacities for both lead and copper ions than the PANFs. The adsorption behaviors of lead and copper ions on the APANFs depended upon the solution pH values, and greater amounts of adsorption were obtained at higher solution pH values. Scanning electronic microscopy and atomic force microscopy indicated that the APANF had a rougher surface than the PANF, and the adsorption of the metal species on the APANF made the surface even rougher. Fourier transform infrared spectroscopy revealed that the amine groups on the surface of the APANF played an important role in the removal of lead and copper ion...
351 citations
TL;DR: In this paper, the formation of indium sulfide buffer layers for high-efficiency copper indium gallium diselenide (CIGS) thin-film solar cells with atomic layer chemical vapour deposition (ALCVD) was studied.
Abstract: This paper presents optimization studies on the formation of indium sulfide buffer layers for high-efficiency copper indium gallium diselenide (CIGS) thin-film solar cells with atomic layer chemical vapour deposition (ALCVD) from separate pulses of indium acetylacetonate and hydrogen sulfide. A parametric study of the effect of deposition temperature between 160° and 260°C and thickness (15–30 nm) shows an optimal value at about 220°C for a layer thickness of 30 nm, leading to an efficiency of 16·4%. Analysis of the device shows that indium sulfide layers are characterised by an improvement of the blue response of the cells compared with a standard CdS-processed cell, due to a high apparent band gap (2·7–2·8 eV), higher open-circuit voltages (up to 665 mV) and fill factor (78%). This denotes high interface quality. Atomic diffusion processes of sodium and copper in the buffer layer are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors reviewed the general features of the deactivation of supported copper metal catalysts in various reactions involving methanol as reactant or product, and found that catalysts are susceptible to thermal sintering via a surface migration process.
Abstract: Laboratory and industrial results are reviewed to elucidate the general features of the deactivation of supported copper metal catalysts in various reactions involving methanol as reactant or product. Most catalyst types are based on Cu/ZnO formulations that contain stabilisers and promoters such as alumina, alkaline earth oxides and other oxides. These additional materials have several roles, including the inhibition of sintering and absorption of catalyst poisons. All copper catalysts are susceptible to thermal sintering via a surface migration process, and this is markedly accelerated by the presence of even traces of chloride. Care must be taken, therefore, to eliminate halides from copper catalysts during manufacture, and from reactants during use. Operating temperatures must be restricted, usually to below 300°C. In methanol synthesis involving modern promoted Cu/ZnO/Al2 O3 catalysts neither poisoning nor coking is normally a significant source of deactivation; thermal sintering is the main cause of deactivation. In contrast, catalyst poisoning and coking have been observed in methanol decomposition and methanol steam reforming reactions.
TL;DR: HCtr1-mediated copper uptake into mammalian cells is regulated by a post-translational mechanism involving copper-stimulated endocytosis and degradation of the transporter, which suggests that intracellular levels of this nutrient must be controlled.
TL;DR: A five-member family (COPT1–5) of putative Arabidopsis copper transporters is described, ascertain the ability of these proteins to functionally complement and transport copper in the corresponding Saccharomyces cerevisiae high-affinity copper transport mutant.
Abstract: Despite copper ions being crucial in proteins participating in plant processes such as electron transport, free-radical elimination and hormone perception and signaling, very little is known about copper inward transport across plant membranes. In this work, a five-member family (COPT1–5) of putative Arabidopsis copper transporters is described. We ascertain the ability of these proteins to functionally complement and transport copper in the corresponding Saccharomyces cerevisiae high-affinity copper transport mutant. The specific expression pattern of the Arabidopsis COPT1–5 mRNA in different tissues was analyzed by RT-PCR. Although all members are ubiquitously expressed, differences in their relative abundance in roots, leaves, stem and flowers have been observed. Moreover, steady-state COPT1 and COPT2 mRNA levels, the members that are most efficacious in complementing the S. cerevisiae high-affinity copper transport mutant, are down-regulated under copper excess, consistent with a role for these proteins in copper transport in Arabidopsis cells.
Patent•
30 May 2003TL;DR: In this article, a copper catalyzed click chemistry ligation process is employed to bind azides and terminal acetylenes to provide 1,4-disubstituted 1,2,3-triazole triazoles.
Abstract: A copper catalyzed click chemistry ligation process is employed to bind azides and terminal acetylenes to provide 1,4-disubstituted 1,2,3-triazole triazoles. The process comprises contacting an organic azide and a terminal alkyne with a source of reactive Cu(I) ion for a time sufficient to form by cycloaddition a 1,4-disubstituted 1,2,3-triazole. The source of reactive Cu(I) ion can be, for example, a Cu(I) salt or copper metal. The process is preferably carried out in a solvent, such as an aqueous alcohol. Optionally, the process can be performed in a solvent that comprises a ligand for Cu(I) and an amine.
TL;DR: The ZnO nanowires were synthesized using vapor-liquid-solid (VLS) growth process on copper-coated p-type Si (1 0 0) substrate as discussed by the authors.
TL;DR: The structure of the APP copper binding domain (CuBD) is solved and it is found that it contains a novel copper binding site that favors Cu(I) coordination, consistent with the CuBD acting as a neuronal metallotransporter.
TL;DR: In this paper, four surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, sodium oleate and polyoxyethylene sorbitan monooleate (TWEEN-80), were investigated in aerated 0.5 mol dm(-3) H2SO4 solutions, by means of electrochemical impedance spectroscopy.
TL;DR: In this article, it was shown that the superconducting Tc of NaxCoO2·1.3H2O exhibits the same kind of behavior on chemical doping that is observed in the high-Tc copper oxides.
Abstract: The microscopic origin of superconductivity in the high-transition-temperature (high-Tc) copper oxides remains the subject of active inquiry; several of their electronic characteristics are well established as universal to all the known materials, forming the experimental foundation that all theories must address. The most fundamental of those characteristics, for both the copper oxides and other superconductors, is the dependence of the superconducting Tc on the degree of electronic band filling. The recent report of superconductivity1 near 4 K in the layered sodium cobalt oxyhydrate, Na0.35CoO2·1.3H2O, is of interest owing to both its triangular cobalt–oxygen lattice and its generally analogous chemical and structural relationships to the copper oxide superconductors. Here we show that the superconducting Tc of this compound displays the same kind of behaviour on chemical doping that is observed in the high-Tc copper oxides. Specifically, the optimal superconducting Tc occurs in a narrow range of sodium concentrations (and therefore electron concentrations) and decreases for both underdoped and overdoped materials, as observed in the phase diagram of the copper oxide superconductors. The analogy is not perfect, however, suggesting that NaxCoO2·1.3H2O, with its triangular lattice geometry and special magnetic characteristics, may provide insights into systems where coupled charge and spin dynamics play an essential role in leading to superconductivity.
TL;DR: In this article, the potential-dependent behavior of poly(ethylene glycol), with or without chloride ion in a copper electroplating bath is investigated using the surface-enhanced Raman spectroscopy technique.
Abstract: The synergic effect of poly(ethylene glycol) together with chloride ion for inhibiting copper deposition in copper electroplating has been of particular interest for some time. In this study, the potential-dependent behavior of poly(ethylene glycol), with or without chloride ion in a copper electroplating bath is investigated using the surface-enhanced Raman spectroscopy technique. The presence of chloride proves to play a significant role in enhancing PEG adsorption to the Cu electrode surface. More importantly, spectroscopic evidence strongly suggests the formation of a PEG−Cu−Cl complex. By comparing experiment with vibrational modes calculated by using the Hartree−Fock method with a 3-21G* basis set, the structure of this complex is proposed to be a three-coordinated Cu center with two oxygen atoms from PEG and one chloride ligand.
TL;DR: In this article, a simple coordination self-assembly method was used to construct the Cu(OH)2 and CuO nanoribbons aligned approximately perpendicular to copper substrate surfaces.
Abstract: Cu(OH)2 and CuO nanoribbon arrays aligned approximately perpendicular to copper substrate surfaces are synthesized by the solution-treatment and subsequent heat-treatment processes. The Cu(OH)2 nanoribbons are fabricated by a simple coordination self-assembly method in an alkaline solution with Cu2+ ions being from the surface oxidation of copper. The CuO nanoribbons are formed by removing water from the Cu(OH)2 nanoribbons through heat treatment. The nanoribbons are ∼50−60 nm in average width and several nanometers in thickness, and the lengths can be well-controlled by varying the reaction temperature and time interval. Transmission electron microscopy, high-resolution TEM, scanning electron microscopy, electron diffraction, and X-ray diffraction techniques have been used to characterize the microstructures and morphologies of the nanoribbon materials.
TL;DR: In this paper, the role of the copper species in the CO oxidation reaction was investigated in terms of species transformation and change in the number of surface lattice oxygen ions, and the light-off behaviors were observed over both Cu and Cu2O powders.
Abstract: Carbon monoxide oxidation activities over Cu, Cu2O, and CuO were studied to seek insight into the role of the copper species in the oxidation reaction. The activity of copper oxide species can be elucidated in terms of species transformation and change in the number of surface lattice oxygen ions. The propensity of Cu2O toward valence variations and thus its ability to seize or release surface lattice oxygen more readily enables Cu2O to exhibit higher activities than the other two copper species. The non-stoichiometric metastable copper oxide species formed during reduction are very active in the course of CO oxidation because of its excellent ability to transport surface lattice oxygen. Consequently, the metastable cluster of CuO is more active than CuO, and the activity will be significantly enhanced when non-stoichiometric copper oxides are formed. In addition, the light-off behaviors were observed over both Cu and Cu2O powders. CO oxidation over metallic Cu powders was lighted-off because of a synergistic effect of temperature rises due to heat generation from Cu oxidation as well as CO oxidation over the partially oxidized copper species.
TL;DR: The tensile properties of nanocrystalline copper with grain sizes <100 nm produced by surface mechanical attrition treatment have been characterized using a microsample testing technique as discussed by the authors, with a yield strength as high as 760 MPa, with a small elongation to failure.
TL;DR: In this article, the electrochemical deposition of copper (Cu) thin film on polycrystalline ruthenium (Ru) electrode surface was investigated in a sulfuric acid plating bath.
Abstract: The electrochemical deposition of copper (Cu) thin film on polycrystalline ruthenium (Ru) electrode surface was investigated in a sulfuric acid plating bath. Scanning electron microscopic characterization indicated that a continuous thin Cu film (150 A and above) could be conformally coated on Ru with good control of thickness. The nucleation and growth of Cu on Ru was studied using the potentiostatic current-transient method. The results support a predominantly progressive nucleation of Cu on the Ru surface. In addition, X-ray diffraction patterns indicated (i) a principally (111) texture of the electrochemically grown Cu on Ru and (ii) the absence of any new phase or compound formation between the two metals, even after annealing up to 800°C. Scotch tape peel tests showed that Cu films adhered strongly to Ru, both before and after the annealing treatments. The lack of metallurgical interaction and strong adhesion between Cu and Ru at elevated temperatures underscore the potential application of Ru as a new Cu diffusion barrier. © 2003 The Electrochemical Society. All rights reserved.
Patent•
14 Nov 2003TL;DR: In this article, the mixture of alternating doses of cobalt(II) bis(N,N'-diisopropylacetamidinate) vapor and hydrogen gas was used to create a very uniform thickness and excellent step coverage in narrow holes.
Abstract: Metal films are deposited with uniform thickness and excellent step coverage. Copper metal films were deposited on heated substrates by the reaction of alternating doses of copper(I) NN'-diisopropylacetamidinate vapor and hydrogen gas. Cobalt metal films were deposited on heated substrates by the reaction of alternating doses of cobalt(II) bis(N,N'-diisopropylacetamidinate) vapor and hydrogen gas. Nitrides and oxides of these metals can be formed by replacing the hydrogen with ammonia or water vapor, respectively. The films have very uniform thickness and excellent step coverage in narrow holes. Suitable applications include electrical interconnects in microelectronics and magnetoresistant layers in magnetic information storage devices.
TL;DR: The sensor works well in the pH range 2.1-6.3 and could be satisfactorily used in presence of 40% (v/v) methanol, ethanol and acetone and is selective for copper over a large number of cations with slight interference from Na(+) and Co(2+) if present at a level 1.5x10(-5) M.
TL;DR: In this paper, the influence of promotion of nickel-containing catalysts with copper on the catalytic activity is discussed, and the maximal conversion of methane into hydrogen and carbon reaches 40% at 675°C at the carbon capacity not lower than 700 ǫg/g Ni under optimal conditions.
Abstract: Steady and efficient decomposition of methane can be achieved at 625–675 °C over copper-promoted (8–15 wt.% of copper) nickel catalysts prepared from a Feitknecht compound precursor. Such catalysts permit one to increase the yield of catalytic filamentous carbon (CFC) and control both microstructural and textural properties of CFC by varying the copper concentration in the catalyst. The maximal conversion of methane into hydrogen and carbon reaches 40% at 675 °C at the carbon capacity not lower than 700 g/g Ni under optimal conditions. The BET surface area of the CFC is 285.9 m 2 /g. The influence of promotion of nickel-containing catalysts with copper on the catalytic activity is discussed.
TL;DR: In this article, the performance of cold sprayed copper coatings is compared to that of cold rolled copper and to coatings prepared by thermal spray methods, in order to explain possible bonding mechanisms.
Abstract: Cold spraying is a coating technique in which the formation of dense, tightly bonded coatings occurs only due to the kinetic energy of high velocity particles of the spray powder. These particles are still in the solid state as they impinge on the substrate. This study correlates optimized deposition parameters with the corresponding microstructure as well as mechanical and conductive behavior of cold sprayed copper coatings in order to explain possible bonding mechanisms. In addition, the performance of cold sprayed copper coatings is compared to that of cold rolled copper and to coatings prepared by thermal spray methods.
TL;DR: The realization of large-scale coupled π-loop arrays based on YBa2Cu3O7-Au-Nb Josephson contacts are reported, of interest as model systems for studying magnetic phenomena—including frustration effects—in Ising antiferromagnets and for designing quantum computers based on flux-qubits with viable quantum error correction capabilities.
Abstract: Since the discovery of high-transition-temperature (high-Tc) superconductivity in layered copper oxides1, many researchers have searched for similar behaviour in other layered metal oxides involving 3d-transition metals, such as cobalt and nickel. Such attempts have so far failed, with the result that the copper oxide layer is thought to be essential for superconductivity. Here we report that NaxCoO2dotyH2O (x 0.35, y 1.3) is a superconductor with a Tc of about 5 K. This compound consists of two-dimensional CoO2 layers separated by a thick insulating layer of Na+ ions and H2O molecules. There is a marked resemblance in superconducting properties between the present material and high-Tc copper oxides, suggesting that the two systems have similar underlying physics
15 Apr 2003
TL;DR: The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of theHPANF.
Abstract: Polyacrylonitrile fiber (PANF) was hydrolyzed in a solution of sodium hydroxide and the hydrolyzed polyacrylonitrile fiber (HPANF) was used as an adsorbent to remove copper ions from aqueous solution. Scanning electron microscopy (SEM) showed that the hydrolysis process made the surface of HPANF rougher than that of PANF. Fourier transform infrared (FTIR) spectroscopy revealed that the HPANF contained conjugated imine (CN) sequences. Batch adsorption results indicated that the HPANF was very effective in adsorbing copper, and the adsorption equilibrium could be reached within 10–20 min. Atomic force microscopy (AFM) showed that some aggregates formed on the surface of the HPANF after copper ion adsorption and the average surface roughness (Ra) value of the HPANF changed from 0.363 to 3.763 nm due to copper adsorption. FTIR analysis indicated that copper adsorption caused a decrease of the light adsorption intensity of the imine (CN) groups at 1573 and 1406 cm−1 wavenumbers, and X-ray photoelectron spectroscopy (XPS) showed that the binding energy (BE) of some of the nitrogen atoms in the HPANF increased to a greater value due to copper adsorption. The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of the HPANF.