On the embedding problem with noncommutative kernel of order p4. VI

In the case of number fields the embedding problem of a p-extension with non-Abelian kernel of order p⁴ is studied. The two kernels of order 3⁴ with generators α, γ and relations α⁹ = 1, [α,α]³=1,[α,αγγ]==1,[αγγ]=α³,γ³=1 or γ³=α³ and the kernel of order 2⁴ with generators α, β, γ and relations α⁴=1 β²,[αγ]=1, [α,γ]=1,[βγ]=α² are considered. For kernels of odd order the embedding problem is always solvable. For the kernel of order 16 the solvability conditions are reduced to those for the associated problems at the Archimedean points, and to the compatibility condition. Bibliography: 9 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 227, 1995, pp. 74–82.     

Structure of thin block copolymer films studied by X-ray reflectivity

Summary X-ray reflectivity may be used to determine the internal structure of thin polymer films. An electron density difference of 10% for polystyrene and polyisoprene is sufficient to distinguish between a random distribution of lamellae, complete orientation parallel to the substrate surface and a surface induced formation of lamellae. The disappearance of the lamellar Bragg-peaks, with heating of the film, shows the transition into the disordered state.     

Plasma B-6 vitamer and plasma and urinary 4-pyridoxic acid concentrations in young women as determined using high performance liquid chromatography.

Plasma B-6 vitamer and plasma and urinary 4-pyridoxic acid concentrations of 21 young white women, 21-27 years, having radiomonitored pyridoxal 5'-phosphate and coenzyme stimulation of erythrocyte alanine aminotransferase activities indicative of adequate vitamin B-6 status were determined in an effort to establish normal ranges for plasma B-6 vitamers. B-6 vitamers and 4-pyridoxic acid were quantitated using reversed phase high performance liquid chromatography with fluorometric and ultraviolet detection. Pyridoxal phosphate values obtained by radioenzymatic and chromatographic, fluorometric and ultraviolet, assays were highly correlated as were pyridoxine phosphate values determined using both detectors. The B-6 vitamer and 4-pyridoxic acid values of these subjects should be of use in the establishment of normal ranges of these congeners in women.