Kinetically determined morphology

Since the publication by the discoverers (3) of chromium oxide catalysts a considerable number of papers devoted to this subject have appeared. Most of them (20-72) deal either with the study of the chromium species on the catalyst surface or with the problem of which of this species is responsible for polymerization. Fewer results have been published on the study of processes determining the polymer molecular weight (78-77) and kinetics of polymerization (78-99). A few papers describe nascent morphology of the polymer formed (100-103). 

Protoplast fusion induced by polyethyleneglycol and Ca was carried out between two auxotrophic mutants of Aspergillus sp. CH-Y-1043. The hybrids obtained showed significant differences in endopectinase activity and morphology compared to the prototrophic strain. Strains grown on lemon peel showed production improvement with respect to the parental strain. Since H15 hybrid showed up to 90% higher endopectinase production than the wild type CH-Y-1043, kinetics of enzyme production in Fernbach flasks and Fermentor (14L) by H15 were determined. 

In the case of layer compounds as electrode materials the kinetics of charge transfer were also studied in some detail taking into account surface recombination which plays an important role here . In the presence of suitable redox systems some materials show very little corrosion . This is due to the morphology of the crystal surfaces and it is generally assumed that corrosion occurs only at steps of different crystal planes . Accordingly, it is not surprising that the highest efficiencies were obtained with some of these materials (Table 1) . The steps also play an important role in the fill factor as determined by surface recombination measurements . ... 

The fundamental reason for the uneven distribution of reactions is that the rate of electrochemical reactions on a semiconductor is sensitive to the radius of curvature of the surface. This sensitivity can either be associated with the thickness of the space charge layer or the resistance of the substrate. Thus, when the rate of the dissolution reactions depends on the thickness of the space charge layer, formation of pores can in principle occur on a semiconductor electrode. The specific porous structures are determined by the spatial and temporal distributions of reactions and their rates which are affected by the geometric elements in the system. Because of the intricate relations among the kinetic factors and geometric elements, the detail features of PS morphology and the mechanisms for their formation are complex and greatly vary with experimental conditions. 

These phenomena cannot be treated Independently, Consequently, the morphology of IPN s is often at a quasi-equlllbrlum state determined by a balance among the several kinetic factors [ l Therefore, in order to understand the domain formation process in IPN s, we should take into consideration the route taken to the final morphology as well as the chemical and physical properties of each constituent. 

---