Effect of the degree of extension on the phase composition and tendency toward mesomorphism of UHMWPE in gel-spun oriented fibers

Structural transformations of UHMWPE-based fibers prepared by orientational drawing have been studied by the combination of SAXS and WAXS methods, photo- and diffractometry, and isometric DSC measurements in a wide temperature range. A sequence of phase transformations and other structural changes has been followed and identified during the orientational deformation of the fibers in a wide range of draw ratios from 1 to 85 within the temperature interval from room temperature to the melting temperature of the polymer.     

Quantum corrections to the conductivity of a two-dimensional disordered system in a strong magnetic field

A system of noninteracting electrons moving in a magnetic field and a field of randomly distributed impurities is considered. An exact expression is obtained for the sum of the series of maximally crossed diagrams; it is valid in an arbitrary magnetic field. It is shown that in the two-dimensional case the relative magnitude of the corrections to the conductivity due to this series reaches 60% in the center of the lower Landau sub-band.Physicotechnical Institute of the Urals Branch of the Russian Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 94, No. 3, pp. 486–495, March, 1993.     

Preparation of the formates of isomeric 5,6-bromohydrins of the pregnane series

Summary The reaction of 3-acetoxy-⁵-steroids with hypobromous acid in dimethylformamide has been studied. It has been shown that this reaction forms formates of bromohydrins.All-Union Scientific-Research Institute of Pharmaceutical Chemicals. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 39–45, January–February, 1973.     

Hierarchies of operators in constructive metric spaces

Infinite hierarchies of operators in constructive metric spaces (CMS's) are constructed, based on the convergence of an approximate representation of the operators. Under fairly general restrictions on the CMS (these restrictions are satisfied by, e.g., a CMS of constructive real numbers and a CMS of general recursive functions) it is shown that these hierarchies are nondegenerate. The hierarchies constructed are used for studying the complexity of operators on general recursive functions. Operators of superposition and bounded and unbounded minimization are considered, along with diverse recursion operators.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akad. Nauk SSSR, Vol. 60, pp. 183–193, 1976. Results announced May 15, 1975.