Showing papers on "Copper published in 1979"

Spectroscopic and redox studies of some copper(II) complexes with biomimetic donor atoms: implications for protein copper centres

Abstract: The redox chemistry and e.s.r. spectra of a number of copper(II) complexes with nitrogen- and sulphur-donor ligands have been examined, including complexes with 2,2′-bi-imidazole, histamine, and cyclic and acyclic saturated amine and thioether ligands. The tetrahedral CuIIS4 centre generated by γ-irradiation of single crystals of a thioacetamide complex of CuI has a low value of |A∥|. Tetrahedral distortion of otherwise tetragonal copper(II) centres increases g∥ and decreases |A∥| for N-, S-, and O-donor ligands, and is a more effective source of reduction of |A∥| than charge effects. The quotient g∥/|A∥| appears to be a convenient empirical index of distortion of the donor set from planar toward tetrahedral, indicating that most type I copper in proteins is tetrahedrally, rather than tetragonally, co-ordinated.

Microstructure of cold-rolled copper

Abstract: Optical and electron metallography have been used to examine the substructures developed in OFHC copper after rolling reductions from 50–97%. These structures are related to the displacements observed at free surfaces after deformation. It is shown that deformation occurs in a series of overlapping stages in each of which a single operating mechanism predominates. At low strains >10% reduction), deformation occurs by slip on planes spaced about 0.03 μm apart to produce an elementary structure. In the range 10–65% reduction, the operative mechanism produces microbands. It is shown that these features correspond to surface slip lines and to particular strain markings in metallographic specimens and that their formation involves the cooperative movement of dislocations. on planes that are much more closely spaced (<0.008 μm) than has been thought previously. At higher levels of strain, instabilities develop in the form of shear bands and these gradually replace microband formation as the dominant def...

Evidence for the nature of true Lewis sites in faujasite-type zeolites

Abstract: An IR spectroscopic study of the reduction of copper-exchanged Linde Na-Y zeolite with hydrogen or carbon monoxide and oxidation with oxygen or oxygen-18 showed that copper(I) and AlO(+1) are formed during reduction, and that oxidation generates copper(II) ions but does not change the aluminum species. Trigonally coordinated aluminum was not detected.

The crystal structures of low chalcocite and djurleite

Abstract: Low chalcocite is monoclinic, space group P2Ifc, with a unit cell having a = 15.246(4)A, b = 11.884(2)A, c = 13.494(3) A, P = 116.35(1t, and containing 48 Cu2S. Its structure was solved by the symbolic addition method, using 5155 independent intensity data measured with MoKcx radiation on an automatic diffractometer. Refinement in anisotropic mode led to R = 0.086. The structure is based on hexagonal-close-packed frame- work of sulfur atoms, with copper atoms occupying mainly triangular interstices. Of the 24 different copper atoms, 21 form triangular CUS3groups, and one is in a distorted CUS4tetrahedron. Djurleite is monoclinic, space group P2Ifn, with a unit cell having a = 26.897(6) A, b = 15.745(3)A, c = 13.565(3) A, P = 90.13(3t, and con- taining 8 CU31S16' The structure was solved by extending the known substructure phases by the symbolic addition procedure, using 5686 inde- pendent intensity data measured with MoKcx radiation. Refinement con- verged at R = 0.116. The structure is similar in general to the low chalcocite structure, but of the 62 different copper atoms, 52 form triangular groups, 9 form distorted tetrahedral groups, and one is in unique linear twofold coordination. Both structures are derived from the high chalcocite structure (P 63/mmc, a = 3.96 A, c = 6.72 A, cell content = 2 Cu2S) which forms a substructure corresponding to the hexagonal-close-packed sulfur framework, but the details of the copper arrangement are entirely different in the two phases. The average Cu - S bond length in the CUS3triangles is 2.32 A in low chalcocite and 2.29 Ain djurleite. The overall average Cu - S distance in the tetrahedra is 2.48 A, but varies from 2.22 to 2.91 A. Each copper atom has from 2 to 8 other copper atom neighbors less than 3.0 A distant, varying up from 2.45 A through a maximum clustering at about 2.78 A. CU- Cu bonding interaction is probably significant but is not clearly understood. * Dedicated to Prof. W. Nowacki on occasion of his 70th birthday

The Corrosion of Copper, Tin, and Their Alloys

Abstract: Part one discusses the corrosion of copper and its alloys, including atmospheric corrosion, oxidation, corrosion by other gases, aqueous and nonaqueous corrosion, stress-corrosion cracking, erosion, radiation, underground corrosion and purposeful corrosion. Part two treats the corrosion of tin and its alloys including atmospheric corrosion, gaseous corrosion, aqueous and non-aqueous corrosion, tinplate and the electrochemistry of the Sn -- Fe couple deterioration by phase change and Sn-whisker formation. Chemical and electrical polishing techniques for copper are described. Quantitative data are emphasized for engineering applications. Numerous ref. -- AATA

Some first row transition metal complexes of nicotinamide and nicotinic acid

Abstract: Some complexes of the chlorides and bromides of manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) with nicotinamide and nicotinic acid have been prepared. These complexes have stoichiometryML 2X2 whereM is a metal ion,L is an organic ligand andX is a halide ion. Spectral and magnetic properties indicate that these compounds have octahedral polymeric structures. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis. In only one instance was a decomposition product of the formulaMLX2 obtained. Its structure was also octahedral.

Three-way catalytic process for gaseous streams

Abstract: A process for the catalytic combustion of carbon monoxide and hydrocarbons and the catalytic reduction of the oxides of nitrogen contained in a gas stream. The process involves intimately contacting the gaseous stream with a catalyst bed comprising copper metal or copper ion and a high silica zeolite.

Inhibitory effects of copper on bacteria related to the free ion concentration.

Abstract: Cu2+ ion determinations were carried out in complex and in inor- ganic salts-glycerol media, to which increasing amounts of Cu(ll) had been added, with the ion-specific Cu(II)-Selectrode. Likewise, complexing capac- ity of bacterial suspensions was estimated by titration with CuS04. Copper-sensitive bacteria, e.g., Klebsiella aerogenes, were inhibited in their growth and survival in the range of 10-8-10-6 M Cu2" ion concentra- tions. In copper-buffered complex media, high copper loads could be toler- ated, as growth proceeded with most of the copper bound to medium components. In low-complexing mineral salts media, in which high Cu2+ ion concentrations exist at low copper loads, there was competition of Cu2+ for binding sites of the cells. Total allowed copper was then determined by the ratio of copper to biomass. Copper-resistant bacteria could be isolated from a stock solution of CuSO4, containing 100 ppm Cu(II). They were of the Pseudomonas type and showed a much higher tolerance towards Cu2l, up to 10-s M.

Rise-time measurements of shock transitions in aluminum, copper, and steel

Abstract: Time‐resolved measurements of shock‐wave rise times have been accomplished for aluminum, copper, and steel to stress levels of 41, 96, and 139 GPa, respectively, using velocity‐interferometer techniques. To within the time resolution of the technique, the shock transition is found to occur within 3 ns in all materials. Based on this upper limit for the transition time, limiting viscosity coefficients of 1000, 3000, and 4000 P are obtained for 6061‐T6 aluminum, OFHC copper, and 4340 steel, respectively, at strain rates above 108 s−1. It is found that the effective viscosity can be expressed as parameters in a Maxwellian relation for an elastic‐plastic solid, in which the viscosity is related to an effective relaxation time. It is also shown that viscosity is inversely proportional to mobile‐dislocation density, which implies that the density of mobile dislocations obtained during shock compression in these materials is well over 109/cm2.

Evidence of Dietary Copper and Zinc Deficiencies

Abstract: The mean daily amounts of copper and zinc found in hospital diets by atomic absorption spectrometry were 0.76 and 9.4 mg, respectively. Comparison of these diets with published data showed median daily amounts of copper and zinc to be 0.78 and 12.0 mg, respectively, for 20 diets made from conventional foods. These amounts of copper and zinc are less than the 2 mg of copper and 13 mg of zinc thought to be required daily by adults. Hospital diets and perhaps diets in general seem to be low in copper and zinc; the amounts of copper are lower than those of zinc in comparison with respective requirements. Common dietary amounts of these elements may cause health problems. ( JAMA 241:1916-1918, 1979)

Measurement of Complexing Materials Excreted from Algae and Their Ability to Ameliorate Copper Toxicity

Abstract: The complexing capacities of three algal exudates and the conditional stability constants of their copper complexes have been determined by an ion exchange method. Their ability to ameliorate coppe...

Copper metabolism in mottled mouse mutants: copper concentrations in tissues during development.

Abstract: The copper content of various organs of `brindled' female heterozygotes and male mice affected by this X-linked mutation are documented at the last day of intrauterine development, at 1 day after birth and at 11 days of age. The findings indicate defective placental transfer of copper in utero, and an even more marked defect in intestinal absorption of copper after birth. In addition there is an abnormal distribution of copper among the tissues of the body once it is absorbed. The mutation produces abnormal accumulation of copper in kidney, in gut mucosa and in testis, whereas liver, brain, plasma and most other organs show diminished copper concentrations. The intestinal malabsorption of copper is accompanied by accumulation of abnormal amounts of the metal in the intestinal-mucosa cells. Copper concentrations in both mucosa and luminal contents rise progressively from duodenum to ileum. Defective upper-intestinal absorption, consequent progressive increase in luminal copper concentration and pinocytosis in the ileum would seem to explain the findings. Radioisotopic studies eliminated the possibility of excessive excretion of copper in bile or across the intestinal mucosa. Detailed comparison with findings in humans with Menkes' syndrome is difficult because of the different stages of development at which the studies have been performed, but the results seem in general to conform very satisfactorily. Those differences seen are probably explicable by known species differences. All the findings are in accord with a hypothesis that the basic defect involves accumulation and retention of copper in the cells of affected tissues such as kidney, gut mucosa and placenta.

Solid‐State Ionics: High Copper Ion Conductivity of the System CuCl ‐ CuI ‐ RbCl

Abstract: A new high copper ion conductivity solid electrolyte has been found in the system. This compound has a copper ion conductivity of 0.34 (Ω‐cm)−1 at 25°C, and activation energies for conduction of 7.0 kJ/mole between 130°C and −25°C, and 19 kJ/mole between −25°C and −140°C, respectively. Powder x‐ray diffraction analysis indicates that the crystal structure of is simple cubic with .