Homogeneity and heterogeneity

Fluctuation theory explaining light scattering in dilute dispersions supposes transient heterogeneities initiated by density variations (Stacey, 1956). 

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Distinguish between heterogeneous and homogeneous mixtures and describe methods of separation (Sections G.1 and G.2). 

The potential for the use of catalysis in support of sustainability is enormous [102, 103]. New heterogeneous and homogeneous catalysts for improved reaction selectivity, and catalyst activity and stabihty, are needed, for example, new catalytic materials with new carbon modifications for nanotubes, new polymers. 

Try to list the most important journals where work in homogeneous catalysis is reported. Why do the heterogeneous and homogeneous catalysis communities publish in different journals ... 

Although we have covered mechanisms relating to solid state reactions, the formation and growth of nuclei and the rate of their growth in both heterogeneous and homogeneous solids, and the diffusion processes thereby associated, there exist still other processes zifter the particles have formed. These include sequences in particle growth, once the particles have formed. Such sequences include ... 

The selective deposition technique seems a surface modification of oxides. In this regard, the modification of material surface is generally carried out in the field of the catalyst preparation. Catalysts are divided into heterogeneous and homogeneous catalysts. The former is well known to be used in the petroleum industry and almost all catalysts are solid, in particular, the supported catalysts. The supported catalysts are composed of the main... 

Both heterogeneous and homogeneous catalysts have been found which allow the hydroamination reaction to occur. For heterogeneously catalyzed reactions, it is very difficult to determine which type of activation is involved. In contrast, for homogeneously catalyzed hydroaminations, it is often possible to determine which of the reactants has been activated (the unsaturated hydrocarbon or the amine) and to propose reaction mechanisms (catalytic cycles). 

Klein, D.H. and Frontal, B. (1964) Heterogeneous and homogeneous nucleation of barium sulfate. Talanta, 11, 1231-1237. 

Thereby, the application of highly sensitive sensors jointly with several specific techniques can be recommended to study complex heterogeneous and homogeneous processes where an experimentalists are faced with an option to analyze small concentrations of active particles in gaseous phase. 

The reaction mechanism for the heterogeneous and homogeneous acid-catalysed esterification were reported to be similar (17). However, there is a major difference concerning the snrface hydrophobicity. Reaction pockets are created inside a hydrophobic environment, where the fatty acid molecules can be absorbed and react further. Water molecules are unlikely to be absorbed on sites enclosed in hydrophobic areas. 

The synthetic value of this reaction should be mentioned. Thus, current production of 5p-steroids from As-3(i-ols, readily available and cheap starting materials, requires a preliminary Oppenauer oxidation or fermentation to the A4-3-keto derivative followed by catalytic hydrogenation under alkaline conditions, as direct catalytic hydrogenation with both heterogeneous and homogeneous systems gives only the 5a isomer. 

Vocabulary of Terms Used in Reactor Design. There are several terms that will be used extensively throughout the remainder of this text that deserve definition or comment. The concepts involved include steady-state and transient operation, heterogeneous and homogeneous reaction systems, adiabatic and isothermal operation, mean residence time, contacting and holding time, and space time and space velocity. Each of these concepts will be discussed in turn. 

Of the many reagents, both heterogeneous and homogeneous, that can facilitate chemical reactions, the cycloamyloses stand out. Reactions can be catalyzed with many species such as hydronium ions, hydroxide ions, general acids, general bases, nucleophiles, and electrophiles. More effective catalysis can sometimes be achieved by combinations of catalytic species as in multiple catalysis, intramolecular catalysis, and catalysis by com-plexation. Only the latter catalysis can show the real attributes of an efficient catalytic system, namely speed and selectivity. In analogy to molecular sieves, selectivity can be attained by stereospecific complexation and speed can be likewise attained if the stereochemistry within the complex is correct. The cycloamyloses, of any simple chemical compound, come the closest to these goals. 

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