Oxides multicomponent scales

Note that the concentrations of additive oxides differ. No attempt has been made to scale this effect with additive concentration). This curious reduction effect is not easily understood but emphasizes the complex nature of the glasses including the possible cooperative involvement of the multiple components. Similarly complex phenomena might influence leaching behavior in the complex, multicomponent glasses of interest for radioactive waste storage. 

Shortly after the introduction of the bismuth molybdate catalysts, SOHIO developed and commercialized an even more selective catalyst, the uranium antimonate system (4). At about the same time, Distillers Company, Ltd. developed an oxidation catalyst which was a combination of tin and antimony oxides (5). These earlier catalyst systems have essentially been replaced on a commercial scale by multicomponent catalysts which were introduced in 1970 by SOHIO. As their name implies, these catalysts contain a number of elements, the most commonly reported being nickel, cobalt, iron, bismuth, molybdenum, potassium, manganese, and silica (6-8). 

A one-pot synthetic method for pyridines on a multigram scale was achieved from a condensation between 2 moles of a jS-keto ester and 1 mole of aldehyde under MWI using bentonite clay as a support and ammonium nitrate as the source of ammonia and oxidant. However, good yields of C-4 substituted pyridines 155 could only be obtained when the aldehydes were aliphatic, but only 5% yield of 155 (R = Ph) and 75% yield of 156 were obtained when benzaldehyde was used. A number of 1,3-dicarbonyl compounds including jS-keto esters were used as building blocks for the multicomponent Hantzsch synthesis (95T6511) whereby symmetrical 155 and 157 and nonsymmetrical pyridines 158 were synthesized (Scheme 32) (98TL1117). 

The decomposition and precipitation of new phases may violate the functional or mechanical properties of the material. These types of phenomena are not only of importance in oxide membranes, but also in oxidation of alloys where solid solutions of two or more oxides or multicomponent compounds may be formed in the oxide scales. 

As in the case of oxide scales the phase morphology of snlfide scales, in particular, on ternary and multicomponent alloys, is veiy complex. As a rale, the scale is a multiphase system and involves many layers different in morphology and phase composition. 

The term polymer nanocomposite (PNC) has evolved, since the first reports in the early 1990s to refer to a multicomponent system, where the major constituent is a polymer or blend thereof and the minor constituent exhibits a length scale below 100nm [1-3], The minor constituent is usually an inorganic filler, called nanofiller, nanoload, or, improperly, nanoparticle. The most commonly used are layered silicates (clays), carbon nanotubes (CNTs), and metals and various metal oxides (silica, titania, zirconia, zinc oxide, etc.). 

As in the case of oxidation, the sulfide scales on the binary as well as on ternary and multicomponent alloys grow essentially by the outward diffusion... 

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