Showing papers on "Copper published in 1989"
TL;DR: Two crystal forms of the multi-copper protein ascorbate oxidase from Zucchini have been analysed at 2.5 A resolution and a model of the polypeptide chain and the copper ions and their ligands has been built.
381 citations
309 citations
TL;DR: The copper complex of histidine has been found to increase the secretion of luteinizing hormone-releasing hormone (LH-RH) from granules of the median eminence, consistent with the newly found role for copper in synthesis of neuroendocrine peptides.
Abstract: Publisher Summary This chapter discusses copper complexes that offer a physiological approach to the treatment of chronic diseases. Copper is recognized as an essential metalloelement just as sodium, potassium, magnesium, calcium, iron, zinc, chromium, vanadium, and manganese. Just as essential amino acids, essential fatty acids and essential cofactors (vitamins), essential metalloelements are required for normal metabolic processes but cannot be synthesized de novo, and daily dietary intake and absorption are required. The adult body contains between 1.4 mg (22 pmol) and 2.1 mg (33 pmol) of copper per kilogram of body weight while the infant body contains three times this amount, consistent with the fact that infant metabolic needs are that much greater than those of adults. The essentiality of copper is now understood as being based upon its recognized need for activation of copper-dependent enzymes. Complexed forms of copper also facilitate absorption, tissue distribution, and tissue utilization. In the nondisease state, these forms of copper account for the physiologic regulation of copper-dependent homeostatic processes. Consistent with the newly found role for copper in synthesis of neuroendocrine peptides, the copper complex of histidine has been found to increase the secretion of luteinizing hormone-releasing hormone (LH-RH) from granules of the median eminence.
309 citations
TL;DR: The results indicate that iron plaque enhances uptake of Zn by the roots but may act as a barrier when large amounts of Fe are deposited on the root surface.
Abstract: summary
The iron plaque on roots of Aster tripolium L. growing in waterlogged salt marsh soil adsorbed appreciable amounts of Zn and Cu, with maximum Zn/Fe and Cu/Fe ratios of 0.1 When concentrations of Zn or Cu adsorbed in the iron plaque are expressed as mg metal kg−1 FeOOH (assuming that iron plaque consists mainly of FeOOH), the Zn and Cu concentrations of the iron plaque was up to 680 and up to 2000 times higher than in the surrounding sediment, respectively. The Zn concentration in red roots (with iron plaque) was higher than in white roots (without iron plaque). Zn concentrations in field sampled roots were correlated with the amount of Zn on the roots and the Zn concentration in the soil, whereas Cu concentrations in the roots were only significantly correlated to the Cu concentration in the soil. In vitro experiments showed that red roots take up more Zn than white roots. Measurement of Zn uptake by excised roots showed that the uptake of Zn into the xylem fluid was significantly higher in roots with 500–2000 nmol Fe cm−2 on the root surface compared to roots with less than 500 or more than 2000 nmol Fe cm−2 on the root surface. The results indicate that iron plaque enhances uptake of Zn by the roots but may act as a barrier when large amounts of Fe are deposited on the root surface. The role of the iron plaque on roots of salt marsh plants growing in soil contaminated with heavy metals is discussed.
269 citations
TL;DR: It was shown in vitro that copper ions stimulate lipid peroxidation in microsomes isolated from roots of plants grown at a normal low copper supply, suggesting that, apart from thiol depletion, direct free radical formation leading to lipid per oxidation might play an important role in the mechanism of copper-induced damage to the permeability barrier in roots of higher plants in vivo.
235 citations
TL;DR: NMR measurements of the nuclear relaxation rate at all copper and oxygen sites in magnetically aligned powder samples of YBa{sub 2}Cu{sub 3}O{sub 7}.
Abstract: We report NMR measurements of the nuclear relaxation rate at all copper and oxygen sites in magnetically aligned powder samples of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ Comparison of the oxygen and copper relaxation reveals a characteristic temperature greater than ${T}_{c}$ The copper relaxation rate is enhanced by antiferromagnetic copper spin fluctuations which are undiminished in the superconducting state The absence of a coherence peak indicates that the superconductive pairing is not of the conventional BCS type
234 citations
TL;DR: In this paper, the major results of a Vickers microhardness study of nanocrystalline palladium and copper produced by the inert-gas condensation method were described.
201 citations
TL;DR: In this article, the superconductivity close to the boiling point of liquid nitrogen has been discovered in the P-Sr-R-Ca-Cu-O system where R is Y or rare earth.
Abstract: Superconductivity close to the boiling point of liquid nitrogen has been discovered in the P-Sr-R-Ca-Cu-O system where R is Y or rare earth. The superconducting compound has been identified as Pb 2 Sr 2 (R,Ca) 1 Cu 3 O 8+ y and the structure of the R=Y compound has been solved by single-crystal X-ray diffraction methods. The structure consists of double CuO 2 sheets interleaved by (Ca,R), a unit which is common to most of the high- T c copper oxide superconductors. A new structural feature found in this system is a double PbO layer separated by a sheet of copper atoms. A non-superconducting oxide of approximate composition (Y,Ca)Sr 2 (Cu,Pb) 3 O 7− y formed as a second phase in some preparations has been also characterized; its structure is related YBa 2 Cu 3 O 7 .
198 citations
TL;DR: In this paper, repeated ion exchange of the ZSM-5 zeolite using aqueous copper(II) acetate solution was found to bring about excess loading of copper ions above 100% of exchange level.
Abstract: Repeated ion exchange of the ZSM-5 zeolite using aqueous copper(II) acetate solution was found to bring about excess loading of copper ions above 100% of exchange level. The catalytic activities of the resulting Cu-ZSM-5 zeolites for direct decomposition of nitrogen monoxide were very high and increased with increasing exchange level. The activity did not decrease even after 30 h of continuous service.
184 citations
TL;DR: The results obtained by ICP-MS for the seven elements considered showed good agreement with the certified values and no interferences occur for the considered isotopes of rubidium, molybdenum, and cesium.
Abstract: A method was developed for the determination of seven trace elements (Fe, Co, Cu, Zn, Rb, Mo, and Cs) in human serum by inductively coupled plasma mass spectrometry (ICP-MS). Sample preparation was kept as limited as possible. As the only sample pretreatment serum samples were diluted with nitric acid and indium was added as an internal standard. The results for iron, cobalt, copper, and zinc were corrected for interferences from polyatomic ions by using a blank solution containing the same concentration of sodium, sulfur, chlorine, and calcium as human serum. For copper and zinc the corrections are small, whereas for iron and cobalt they are important. No interferences occur for the considered isotopes of rubidium, molybdenum, and cesium. In order to test the accuracy and precision of the analytical technique, a "second-generation biological reference material (human serum)" was analyzed. The results obtained by ICP-MS for the seven elements considered showed good agreement with the certified values.
167 citations
AT&T1
TL;DR: In this article, substitution of fluorine for oxygen in T′-phase Nd2CuO4 provides an alternative route to achieving formal reduction of copper, electron conductivity and superconductivity at temperatures as high as 27 K.
Abstract: THE recent report1 of superconductivity in Nd1,85Ce015CuO4 is the first example of a high-transition-temperature (high– Tc) super-conductor with electrons as the charge carriers and a formal copper oxidation state of less than +2 All previously characterized copper oxide superconductors are hole-doped, and the copper is formally oxidized Here we show that substitution of fluorine for oxygen in T′-phase Nd2CuO4 provides an alternative route to achieving formal reduction of copper, electron conductivity and superconductivity at temperatures as high as 27 K This result is unusual, because anionic rather than cationic substitution gives rise to the superconductivity
Patent•
09 Aug 1989TL;DR: In this paper, a structure for thin films of Group I-III-VI compound semiconductors such as copper indium diselenide for use in heterojunction photovoltaic devices fabricated on metal substrates is presented.
Abstract: A structure for, and method of making, thin films of Group I-III-VI compound semiconductors such as copper indium diselenide for use in heterojunction photovoltaic devices fabricated on metal substrates. An interfacial film containing gallium is first deposited upon the substrate. Thereafter, copper and indium films are deposited and the resulting stacked film is heated in the presence of a source of selenium to form copper indium diselenide semiconductor material with improved adhesion to the substrate and improved performance.
TL;DR: All disinfection systems, regardless of temperature or free chlorine concentration, showed increase inactivation rates when 400 and 40 micrograms of copper and silver per liter was added; however, this trend was significant only at 0.4 mg of free chlorine per liter.
Abstract: Water disinfection systems utilizing electrolytically generated copper and silver ions (200 and 20, 400 and 40, or 800 and 80 micrograms/liter) and low levels of free chlorine (0.1 to 0.4 mg/liter) were evaluated at room (21 to 23 degrees C) and elevated (39 to 40 degrees C) temperatures in filtered well water (pH 7.3) for their efficacy in inactivating Legionella pneumophila (ATCC 33155). At room temperature, a contact time of at least 24 h was necessary for copper and silver (400 and 40 micrograms/liter) to achieve a 3-log10 reduction in bacterial numbers. As the copper and silver concentration increased to 800 and 80 micrograms/liter, the inactivation rate significantly (P less than or equal to 0.05) increased from K = 2.87 x 10(-3) to K = 7.50 x 10(-3) (log10 reduction per minute). In water systems with and without copper and silver (400 and 40 micrograms/liter), the inactivation rates significantly increased as the free chlorine concentration increased from 0.1 mg/liter (K = 0.397 log10 reduction per min) to 0.4 mg/liter (K = 1.047 log10 reduction per min). Compared to room temperature, no significant differences were observed when 0.2 mg of free chlorine per liter with and without 400 and 40 micrograms of copper and silver per liter was tested at 39 to 40 degrees C. All disinfection systems, regardless of temperature or free chlorine concentration, showed increase inactivation rates when 400 and 40 micrograms of copper and silver per liter was added; however, this trend was significant only at 0.4 mg of free chlorine per liter.
TL;DR: The lower temperature limit for void formation was found to lie between 182 and 220 °C, with a maximum swelling of about 0.5% at 300 to 350 °C and no swelling at 500 °C as mentioned in this paper.
TL;DR: In this article, two series of discotic liquid crystals, one based on metal-free and the other on copper containing phthalocyanine (Pc) as the central core and eight peripherally n-alkoxy groups (C6−C12) as substituents have been synthesized and their mesomorphic properties and structural parameters have been determined.
Abstract: Two series of discotic liquid crystals, one based on metal-free and the other on copper containing phthalocyanine (Pc) as the central core and eight peripherally n-alkoxy groups (C6–C12) as substituents have been synthesized and their mesomorphic properties and structural parameters have been determined. These compounds represent a series totally devoid of polymorphism, the mesophase in all cases being Dho. In the solid state an orthorhombic two dimensional lattice with four molecules per unit cell and a presumably tilted stacking is present, while in the mesophase the planes of the molecules are on average perpendicular to the direction of the stacks. The aggregation behaviour of the C8, C10 and C12 homologues was studied as a function of solvent polarity and of concentration. The electrical properties of the copper complexes of the n-dodecoxy and n-octoxy derivatives have been determined by means of complex impedance spectroscopy and compared with those of the non-mesogenic CuPc.
TL;DR: In this paper, a new copper oxide superconductor with an onset tem-perature of 28 K was found in the Nd-Ce-Sr-Cu-O system.
Abstract: Recently, a new copper oxide superconductor with an onset tem-perature of 28 K was found in the Nd–Ce–Sr–Cu–O system1. The superconducting phase was identified by X-ray diffraction and electron microscopy2, and the metal-atom positions are identical with those in the K2NiF4 or Nd2CuO4 structure3, except for the order of the cations Nd(Ce) and Sr. Here we report the refinement of the crystal structure using neutron powder diffraction. We find that it comprises alternating slabs of the K2NiF4 and Nd2CuO4 structures, and that all the copper atoms are crystallographically identical, with oxygen in fivefold (square-pyramidal) coordination. In having only one kind of copper site, this new compound is structurally simpler than the other CuO5-bearing superconductors such as YBa2Cu3O7, and may therefore be particularly helpful in the effort to understand the origins of high-temperature superconductivity.
TL;DR: Results of the proposed method correlated well with those determined by standard atomic absorption spectrophotometric techniques, and did not interfere with Iron, zinc, cadmium, cobalt, and lead.
Abstract: We have developed a sensitive procedure for determination of serum copper by use of the color reagent 4-(3,5-dibromo-2-pyridylazo)-N-ethyl-N-sulfopropylaniline. After mixing serum sample and reagent, and incubating at 37 degrees C for 5 min, we measure the absorbance of the resulting chelate complex at 580 nm (molar absorptivity, 80,000 L.mol-1.cm-1). Results of the method varied linearly with copper concentration to at least 5 mg/L; the lower limit of detection was 0.1 mg/L. Within-run CVs were 1.6% and 3.3% for copper concentrations of 1.03 and 0.72 mg/L, respectively (n = 10 each). Between-run CV was 2.8% at 1.22 mg/L (n = 14). Results of the proposed method (y) correlated well with those determined by standard atomic absorption spectrophotometric techniques (x): y = 0.99x - 0.02 mg/L; Syx = 0.08; r = 0.977; n = 56. Iron, zinc, cadmium, cobalt, and lead do not interfere.
TL;DR: In this paper, the electron-doped superconductor Nd,1.85Ce0.15CuO4-δ exhibits almost no pressure effect on Tc up to 2.5 GPa.
Abstract: THE recent discovery of the electron-doped superconductors1 added fresh fuel to controversies about the mechanism of high-temperature superconductivity in copper oxide compounds. The superconducting transition temperature (Tc) of almost all the hole-doped copper oxide compounds increases with increasing pressure2. The pressure coefficient has a large positive value compared with a typical conventional (BCS) superconductor. A systematic survey of the TcS of Y–Ba–Cu–O and La–Sr–Cu–O compounds has shown that Tc is strongly correlated with hole concentration3–5, but the Hall coefficient is only weakly dependent on pressure6,7. These results indicate that the large change in Tc with pressure is caused, not by a change in hole concentration, but by other factors related to changes in the interatomic distances. Here we report that the newly discovered electron-doped superconductor Nd,1.85Ce0.15CuO4–δ exhibits almost no pressure effect on Tc up to 2.5 GPa, in remarkable contrast to the hole-doped superconductor Nd1.3Ce0.3Sr0.5CuO4–δ. The Cu–O pyramids characteristic of the hole-doped compounds lose their apical oxygens to become square planes in the electron-doped materials. If the pressure effect on Tc does arise from changes in bond lengths, the difference in behaviour of the two compounds points to the involvement of the bond between copper and apical oxygen, which is missing in the electron-doped material.
TL;DR: In this paper, the defect structure of undoped CuInS2 was revealed by combining the studies of electrical, photoluminescence and stoichiometric analyses, and the ionization energies were determined to be 0.038, 0.68 and 0.145eV for the sulfur vacancy, indium interstitial and indium occupying the copper vacancy, respectively.
TL;DR: In this article, the vapor pressure of liquid copper (II) hexafluoroacetylacetonate was determined over the temperature range 97°•120°C and the standard enthalpy of evaporation was found to be.
Abstract: Thermally activated decomposition of the vapor phase of copper (II) hexafluoroacetylacetonate was studied. It was found that the temperature at which the decomposition is carried out influences dramatically the chemical composition of deposits; the higher the temperature, the more carbon is incorporated. Pure copper deposits having resistivities of 3–7 μΩ cm were obtained at substrate temperatures of 340°–390°C. It is believed that in this temperature range, breaking of the metal‐ligand bond of the copper compound takes place while at higher temperatures the onset of the ligand decomposition itself becomes significant. The vapor pressure of liquid copper (II) hexafluoroacetylacetonate was determined over the temperature range 97°‐120°C. The standard enthalpy of evaporation was found to be .
TL;DR: The diffusion of silver in nanocrystalline copper was measured at various temperatures between 303 and 373 K as discussed by the authors, and the activation enthalpies were determined by electron beam microanalysis on taper sectioned specimens.
TL;DR: In this article, small clusters of silver are formed as well as colloidal particles of silver metal in AgClO 4 solutions containing sodium poly (phosphate) and they survive for about 1 h.
TL;DR: The biogeochemical importance and fate of this copper is poorly understood for open ocean regions as discussed by the authors, but it is known that atmospheric aerosols collected at Enewetak Atoll, in the tropical North Pacific were exposed to seawater and artificial rainwater in laboratory experiments.
Abstract: Atmospheric deposition contributes copper to the surface ocean. The biogeochemical importance and fate of this copper is poorly understood for open ocean regions. Atmospheric aerosols collected at Enewetak Atoll, in the tropical North Pacific, were exposed to seawater and artificial rainwater in laboratory experiments. Aerosol copper during the high-dust season at Enewetak Atoll is made up of aluminosilicate, oceanic, and possibly soil organic matter components. During the low-dust season, aerosol copper appears to be essentially all of oceanic origin. Virtually all nonaluminosilicate copper in marine aerosols collected at Enewetak is soluble in seawater. Dissolved organic matter and possibly cations in seawater increase the dissolution of aerosol copper. The net atmospheric flux of soluble copper to the tropical North Pacific near Enewetak is approximately 0.13 nmol cm−2 yr−1 out of a total net atmospheric copper flux of 0.14 nmol cm−2 yr−1. Atmospheric deposition supplies roughly the same quantity of soluble copper to tropical open North Pacific surface waters as does upwelling to eastern North Pacific surface waters. Atmospheric copper deposition, which appears to be primarily of natural origin, may be the most important input of copper to the surface waters of the central gyre of the North Pacific.
TL;DR: The hepatocyte responds to an increased copper load by sequestering excess copper in an increased number of lysosomes that then empty their contents directly into bile, providing direct evidence that exocytosis of lYSosomal contents into biliary canaliculi is the major mechanism for biliary copper excretion in hepatic copper overload.
Abstract: We investigated the hypothesis that lysosomes are the main source of biliary copper in conditions of hepatic copper overload. We used a rat model of oral copper loading and studied the relationship between the biliary output of copper and lysosomal hydrolases. Male Sprague-Dawley rats were given tap water with or without 0.125% copper acetate for up to 36 wk. Copper loading produced a 23-fold increase in the hepatic copper concentration and a 30-65% increase in hepatic lysosomal enzyme activity. Acid phosphatase histochemistry showed that copper-loaded livers contained an increased number of hepatocyte lysosomes; increased copper concentration of these organelles was confirmed directly by both x ray microanalysis and tissue fractionation. The copper-loaded rats showed a 16-fold increase in biliary copper output and a 50-300% increase in biliary lysosomal enzyme output. In the basal state, excretory profiles over time were similar for biliary outputs of lysosomal enzymes and copper in the copper-loaded animals but not in controls. After pharmacologic stimulation of lysosomal exocytosis, biliary outputs of copper and lysosomal hydrolases in the copper-loaded animals remained coupled: injection of colchicine or vinblastine produced an acute rise in the biliary output of both lysosomal enzymes and copper to 150-250% of baseline rates. Aftermore » these same drugs, control animals showed only the expected increase in lysosomal enzyme output without a corresponding increase in copper output. We conclude that the hepatocyte responds to an increased copper load by sequestering excess copper in an increased number of lysosomes that then empty their contents directly into bile. The results provide direct evidence that exocytosis of lysosomal contents into biliary canaliculi is the major mechanism for biliary copper excretion in hepatic copper overload.« less
TL;DR: In this article, the authors used transmisssion electron microscopy to detect and analyse the nature and evolution of interfacial compounds as a function of copper oxidation and bonding time Chemical reactions lead to the formation of the binary oxide CuAlO2 and the reversibility of chemical reactions appear to be very dependent on the amount of oxygen present in the system.
Abstract: Bonding between copper and alumina can be obtained by the “solid state bonding” process and the “liquid phase bonding” process The strength of interfaces has been tested mechanically using shear tests, tensile tests and fracture toughness tests The effects of bonding parameters on bond strength have been studied Observations by transmisssion electron microscopy have been performed to detect and analyse the nature and evolution of interfacial compounds as a function of copper oxidation and bonding time Chemical reactions lead to the formation of the binary oxide CuAlO2 The stability of this compound and the reversibility of chemical reactions appear to be very dependent on the amount of oxygen present in the system
TL;DR: In this paper, the Jahn-Teller distortion of the copper ferrospinel has been investigated, and the critical number of octahedral-site Cu 2+ ions per formula unit for a cooperative distortion to tetragonal symmetry at room temperature is ca 0.8.