Economy of DNA Coding Sequences

Heckman, J. SamolT, B. Alzner-Deweerd, S. Yin, and N. L. RajBhandary, Proc. Natl. Acad. Sci. USA, mo,n,3i59. 

This Report continues to review those developments of significance in the area important in the context of this volume, i.e., polymers essentially linear in nature, and consisting of backbone structures made up of predominantly inorganic elements. The review is limited by size to polymers derived from the most important and active areas of the poly(organosiloxane)s, poly(organophosphazene)s and polythiazyls. 

The high level of publication in this area continues to increase across the broad area of this polymer class, whose unique combination of properties lends itself to involvement in the widest range of commercial applications. 

The synthesis of useful low-molecular-weight organosiloxane polymers derived from mineral sources has been reported. The aqueous phase emulsion polymerization of dimethylcyclic monomers D , n = 3—7, has been studied, and mechanisms have been proposed postulating the combined role as initiator-surfactant in systems polymerized by tetra-alkyl ammonium hydroxides.  

Molecular Structure.—A review has appeared that compares the relationship between polymer structure and surface-active properties of the poly(dimethyl siloxane)s (PDMS) with that of hydrocarbon and fluorocarbon polymer systems. A mathematical study of the spreading of (PDMS) oil drops has been presented and experimental data shown to be in good agreement with predictions. Quantitative comparison of previously published n.m.r. spin-relaxation data for poly(diethyl iloxane)s with theoretical predictions for a variety of motional processes, have allowed both the nature and time scale of molecular motions to be identified.  

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