Chemical and Structural Homogeneity

Ideally, an amorphous metal alloy should be chemically and structurally isotropic. Isotropic surfaces would be ideal for catalytic applications, since any structural and chemical heterogeneity can impede the selectivity with which a particular chemical reaction is catalyzed. However, several studies [4.18,50,57-59] reveal that the surface of glassy metals prepared by meltspinning may not be as homogeneous as expected. Structural as well as chemical 

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Another feature of fused catalytic compounds can be the generation of a melt during catalytic action. Such supported liquid phase (SLP) catalysts consist of an inert solid support on which a mixture of oxides is precipitated which transform into a homogeneous melt at reaction conditions. These systems provide, in contrast to the case described before, a chemically and structurally homogeneous reaction environment. The standard example for this type of catalyst is the vanadium oxide contact used for oxidation of SO2 to S03. 

Important properties of glassy metals influencing the structural and chemical properties of the catalyst derived from them are (i) chemical composition (ii) chemical and structural homogeneity (iii) thermal stability and crystallization behavior (iv) oxidation behavior (v) dissolution of gases and (vi) segregation phenomena. These factors together with the conditions used for the chemical transformation of the precursor are crucial to obtain catalysts with the desired properties. 

Thus, at the present time it is not so important only to develop new alloys, but also special methods of melting which guarantee reproducibility of their properties. Here, the degree of chemical and structural homogeneity of metal is so much important characteristic that its improvement should be... 

The technology of MEM of multicomponent titanium alloys has been developed which can produce ingots with a high chemical and structural homogeneity and precise preset chemical composition. 

Solubilization of conjugated polymers led to enormous progress in the spectroscopic investigations of these compounds. In particular H, C NMR and uv-vis-nir spectroscopic studies enabled careful control of the chemical and structural homogeneity of individual polymer chains. This, in turn, resulted in the development of synthetic procedures, in which the creation of conjugation perturbing defects could be efficiently limited [11-14]. 

All electronic and electro-optic applications of poly-conjugated systems require the preparation of polymers with high chemical and structural homogeneity. Several optical and electrical properties of conjugated polymers such as their quantum efficiency of electroluminescence or maximum conductivity after doping can be correlated with the concentration of conjugation breaking defects introduced to the polymer upon its preparation. 

EVF level the pool temperature field, intensify heat and mass transfer in the metal pool, thus providing the formation of metal with a high chemical and physical homogeneity. Vibration of the melt allows metal structure refining. 

It has been the intention of the author in this review to examine the roles played by zinc ion in homogeneous solution catalysis both for small molecule-zinc ion complexes and for zinc-metalloenzymes. Emphasis is placed on the integration of physical-inorganic mechanistic concepts derived from studies on small molecule systems with the accumulated kinetic, chemical, and structural information available on select enzyme examples in order that reasonable mechanistic hypotheses might be developed for the roles played by zinc ion in enzymatic catalysis. 

SIMS can be used for qualitative and quantitative analyses of elemental constituents for compound identification, molecular weight determination, and chemical and structural information and to examine lateral and in-depth sample homogeneity. 

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