Chemistry in Interphases-A New Approach to Organometallic Syntheses and Catalysis.

Combining the advantages of homogeneous and heterogeneous catalysis is still a problem that has not been satisfactorily solved. Chemistry in interphases offers a new approach for overcoming the difficulties, as is described in this article. Owing to the swellable or porous matrix, an interphase represents a state which in the most favorable case is similar to that of a solution. Moreover the proper choice of a mobile hybrid copolymer enables the control of the density and accessibility of the reactive centers, which results in a distinct improvement of the activity of the catalysts (two examples are shown schematically).

ptGAs-Genetic Algorithms Evolving Noncoding Segments by Means of Promoter/Terminator Sequences.

In this article we present work on chromosome structures for genetic algorithms (GAs) based on biological principles. Mainly, the influence of noncoding segments on GA behavior and performance is investigated. We compare representations with noncoding sequences at predefined, fixed locations with 'junk' code induced by the use of promoter/terminator sequences (ptGAs) that define start and end of a coding sequence, respectively. As one of the advantages of noncoding segments a few researchers have identified the reduction of the disruptive effects of crossover, and we solidify this argument by a formal analysis of crossover disruption probabilities for noncoding segments at fixed locations. The additional use of promoter/terminator sequences not only enables evolution of parameter values, but also allows for adaptation of number, size, and location of genes (problem parameters) on an artificial chromosome. Randomly generated chromosomes of fixed length carry different numbers of promoter/terminator sequences resulting in genes of varying size and location. Evolution of these ptGA chromosomes drives the number of parameters and their values to (sub)optimal solutions. Moreover, the formation of tightly linked building blocks is enhanced by self-organization of gene locations. We also introduce a new, nondisruptive crossover operator emerging from the ptGA gene structure with adaptive crossover rate, location, and number of crossover sites. For experimental comparisons of this genetic operator to conventional crossover in GAs, as well as properties of different ptGA chromosome structures, an artificial problem from the literature is utilized. Finally, the potential of ptGA is demonstrated on an NP-complete combinatorial optimization problem.