Conformation of linear polyethylene in 1-chloronaphthalene: Light scattering characterization of polymers. IV

Light scattering measurements were carried out on a linear polyethylene sample NBS 1475 in 1-chloronaphthalene at 135 and 115°C to determine the weight-average molecular weight, the second virial coefficient A₂, and the z-average mean-square radius of gyration. By use of these results, the system is analyzed in terms of the interpenetration function Ψ for A₂. Observed values of A₂ are rather large but the excluded volume is nevertheless relatively small. Such behavior seem to be similar to that of semiflexible polymers. The characteristic ratio C_n,LS as determined by light scattering is found to be almost twice the literature value of 6.7, which was obtained from viscosity measurements. This discrepancy is explained by comparing the theoretical value of the Flory viscosity parameter Φ at the nondraining limit with values calculated from the light scattering results.     

Atomic emission spectrometry of metal oxides using shock tube excitation

The behavior of powdered samples in the region behind the incident and reflected shock wave were investigated. When the particle size is less than 8 μm, the powdered samples are effectively vaporized and excited to emit spectral lines. It was shown that the sample particles are scattered behind the incident wave and concentrated again in a narrow portion near the observation window by the use of a reflector so that intense emission can be attained. As an excitation source, the shock tube was used for the determination of trace metals contained in copper oxide.     

Electrochemical behavior of nitrogen heterocycles in N,N-dimethylformamide-water and aqueous buffer solution

The electrochemical behavior of ten nitrogen heterocycles was investigated in DMF-water and aqueous buffer solution. On the basis of these data, the effect of proton on the reduction behavior in DMF-water media and the reduction pathway in aqueous buffer solution ware phenomenologically classified. The adsorption phenomena in aqueous buffer solution and the correlation of reduction behavior with structure and reactivity were discussed. The structure of electrolytic products was also estimated and identified by negative electron density distributions of radical anion, GC-MS and spectrophotometry.     

Inversion of enantioselectivity of asymmetric biocatalytic decarboxylation by site-directed mutagenesis based on the reaction mechanism

The introduction of two mutations (G74C/C188S) based on the estimated reaction mechanism resulted in the inversion of enantioselectivity of arylmalonate decarboxylase, which catalyses the asymmetric decarboxylation of arylmethylmalonate to give optically active arylpropionate.     

Raman scattering in low wavenumber region as a new probe to structural properties of microcrystalline silicon

The structural properties of microcrystalline silicon (μc-Si) are studied by Raman scattering. It is found that the intensity of each Raman band closely correlates with the absorption coefficient in the interband region and that the Raman band at ca. 150 cm^?1 is a sensitive probe to randomness of Si-Si bonding structure in μc-Si.     

Tunneling spectroscopic study on the superconductivity of (TMTSF)2ClO4 crystals

We observed the energy gap spectra for (TMTSF)₂ClO₄-Al₂O₃-Au junctions at 1.5 K by measuring their tunneling current characteristics. The superconducting gap was estimated to be less than 2 meV (T_c<6 K) which is much smaller than the previously reported value, 8 meV.     

E 6,7,8 magnetized extra-dimensional models

We study 10D super Yang–Mills theory with the gauge groups E ₆, E ₇ and E ₈. We consider the torus/orbifold compactification with magnetic fluxes and Wilson lines. They lead to 4D interesting models with three families of quarks and leptons, whose profiles in extra dimensions are quasi-localized because of magnetic fluxes.     

-kernels of Lie groups

We study a filtration on the group of homotopy classes of self maps of a compact Lie group associated with homotopy groups. We determine these filtrations of and completely. We introduce two natural invariants and defined by the filtration, where is a prime number, and compute the invariants for simple Lie groups in the cases where Lie groups are -regular or quasi -regular. We apply our results to the groups of self homotopy equivalences.