Copper substitution

In the preceding section, the electrochemistry of copper-substituted derivatives shows an example of mixing up of the substituent metal cation and tungsten waves, but this process was accompanied by the deposition of Cu . Analogous merging was studied in detail in the case of ay- and a2"[Fe (0H2)P2Wi706i] , where this complicating feature was absent [89]. 

Four-pulse DEER measurements were performed on a dimer of copper-substituted azurin molecules with a Cu(II)-Cu(II) distance of 26 A.27 Experiments were performed at 10 K with pulse lengths of 16 ns for ji/2 and 32 ns for p pulses and a 75 MHz difference between the frequencies of the pump and observe pulses. Analysis of the dipolar frequencies required consideration of orientation selection in both the pump and observe pulses because only a subset of the Pake pattern is represented in the Fourier transform of the experimental data. For this sample the orientation of the interspin vector relative to the g matrices of the two centres was known from high-field EPR. Dipolar modulation could not be detected for a second dimer with a copper-copper distance of 14.6 A.27... 

CW line-shape simulation. Simulation of the EPR spectrum of di-copper-substituted aminopeptidase from Aeromonas proteolytica found a zero field splitting that corresponded to an interspin distance of about 5 A, which is in good agreement with the X-ray crystallographic value of 4.93 A.55... 

These examples illustrate that biomolecules may act as catalysts in soils to alter the structure of organic contaminants. The exact nature of the reaction may be modified by interaction of the biocatalyst with soil colloids. It is also possible that the catalytic reaction requires a specific mineral-biomolecule combination. Mortland (1984) demonstrated that py ridoxal-5 -phosphate (PLP) catalyzes glutamic acid deamination at 20 °C in the presence of copper-substituted smectite. The proposed pathway for deamination involved formation ofa Schiff base between PLP and glutamic acid, followed by complexation with Cu2+ on the clay surface. Substituted Cu2+ stabilized the Schiff base by chelation of the carboxylate, imine nitrogen, and the phenolic oxygen. In this case, catalysis required combination of the biomolecule with a specific metal-substituted clay. 

POLYBASITE. A mineral antimony sulfide of silver (Ag.C n)t. Sb,S. in which copper substitutes for silver to approximately 30 atomic percent. It crystallizes in the monoclinic system hardness, 2-3 specific gravity, 6.3 color, black, dark ruby red in thin splinters with metallic luster nearly opaque. From the Greek, meaning many, suggesting the many-metal basis. 

The di-copper-substituted y-Keggin silicotungstate [y-H2SiWio036Cu2( j,-l, 1-N3)2]4- could act as an effective homogeneous catalyst for the oxidative homocoupling of various kinds of alkynes, including aromatic, aliphatic and heteroatom-containing ones (6.8) [108] ... 

There are parallel achievements at the University of Pennsylvania, (Park etai, 1999 2000 2001 Gorte etai, 2000), using anodes with copper substituted for nickel to avoid carbon formation. The last two papers include the electrochemical oxidation of dry fuels other than methane, for example gasoline and diesel, the chemical exergy of which is difficult to calculate, since they are mixtures requiring separative work. 

Lithium alkynides in tetrahydrofuran or dioxane often give substitution products with secondary haloalkanes, while alkynide Grignard reagents do not usually react with haloalkanes except in the presence of other metals such as cobalt and copper. Substitution of iodine or bromine for chlorine in the halo-alkane often leads to an increased yield of the alkylation product and alkanesulfonates may give greater yields than haloalkanes. Scheme 1 illustrates examples of alkylation of haloalkanes and alkyl sulfates with alkynides of Group I metals. 

It is seen from Table,2 that the conversion and selectivity to benzaldehyde increases with increase in Copper content in BaPbux-yBixCuyOs. Copper substituted BaPbi-x-yBixCuyOj are found to be more active and selective than BaPbi-xBixOs. This may be attributed to the difference in ease of reducibility of the perovskite oxides. 

Pace M D, Barger WR and Snow AW 1989 Molecular packing and iodine doping of oxovanadium-substituted and copper-substituted tetrakis(cumylphenoxy)phthalo-cyanine Langmuir-Blodgett films studied by ESR Langmuir 5 973-8... 

The evolution of the activity as a function of copper substitution is given on Figure 2 the shape of the curve may be compared to the one obtained by Chan et al. [9] for the oxidation of CO over copper substituted lanthanum manganates although these authors tested neither x = 0.5 nor x > 0.8. For x = 0.5 there is a maximum in activity, which may be related to the maximum in NO adsorption as reported by Mizimo et al. [15],... 

Figure 2. Activity of Lao.8Sro.2Mni-xCux03 x as a function of copper substitution...

Qi, X., Zhang, L., Xic, W., Ji, T. and Li. R. (2004). Synthesis of copper-substituted aluminophosphatc molecular sieves (CuAPO-11) and their catalytic behavior for phenol hydroxylation. Applied Catalysis A Generaly 21 by 89-94. 

The mechanism of charge compensation in copper substituted manganites has to include participation of oxygen vacancies and is described by two simultaneous reaction of substitution of Cu for Mn 2Mn Mn -l-Cu and 2Mn 2Cu +Vq. Realization of such... 

An alloy contains atoms of more than one element and has the properties of a metal. In a solution alloy the components are randomly dispersed. In a heterogeneous alloy the components are not evenly di rsed and can be distinguished at a macroscopic level In an intermetallic compound the components have interacted to form a compound substance, as in CU3AS 12.39 Statement (b) is false. 12.41 (a) True (b) false (c) false 12.43 (a) Nickel or palladium, substitutional alloy (b) copper, substitutional alloy (c) silver, substitutional alloy 12.45 (a) True (b) false (c) false (d) false... 

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