Morphology of oligomers and their network polymers

Summary The morphology of di (4-methacryloxyethylene carbamate toluylen-2-carbamic) esters of oligoethylene glycols (OUM) with different molecular weight, of their network polymers and of model oligomers without methacrylic groups was studied. The supermolecular structure of oligomers is found to depend on molecular weight. Globular structure is typical for low molecular weight oligomers with M_n1200. The structure of crystalline samples with M= 1600–3600 is lamellar. The latter is retained on melting. It is transformed into globular structure at a temperature much higher than the melting point. A correlation exists between the morphology of polymerizable oligomers and their network polymers. The process of network formation from oligomers is extremely complicated. Irrespective of the mechanism it is influenced by MWD, FTD, intermolecular interaction and a number of other factors. The interconnection between the morphology of polymerizable oligomers and the supermolecular structure of their crosslinked polymers has not been sufficiently studied.Information about this connection facilitates phenomenological understanding of the network formation process.Presented at the 7th IUPAC Discussion Conference Polymer Networks, Karlovy Vary, CSSR, September 1980     

Methods of manufacture of aluminum powders and their fields of application

Conclusions Aluminum powders, flakes, pastes, and granules are being successfully used in various branches of the national economy, including powder metallurgy. The present-day scale of industrial manufacture of aluminum and aluminum alloy powder products can satisfy virtually all the known demands from industry. There is a need to increase industrial production of aluminum alloy granules by the method of centrifugal casting of melts for the development of granule metallurgy, which enables successfully to process some materials, in particular low-grade and secondary aluminum.Translated from Poroshkovaya Metallurgiya, No. 12(264), pp. 32–37, December, 1984.     

The mechanism of the reaction forming tryptophanyl-tRNA, catalyzed by tryptophan:tRNA-ligase

The rates of tryptophanyl-tRNA formation catalyzed by beef pancreas tryptophanyl-tRNA synthetase were measured in a concentration range of each substrate (tryptophan, ATP and yeast tRNATrp) and also in the presence of various concentrations of substrate analogues (tryptamine and alpha,beta-methylene analogue of ATP) concentrations. The data obtained were compared with the kinetic equations which described various possible mechanisms of the reaction. The comparison of the mechanisms was based on the calculation of relative probabilities of each hypothesis the efficiency of which was demonstrated earlier. The calculations have shown that two mechanisms according to which the intermediate enzyme-aminoacyl-adenylate complex formation involves the enzyme-aminoacyl-tRNA complex are the most probable ones.