Surface electronic structure of binary metal oxide catalyst ZrO2/SiO2

The surface electronic structure of the binary metal oxide ZrO₂/SiO₂ was studied by means of XPS and the decrete variational (DV) Xα cluster model calculation. The results show that when ZrO₂, was supported on SiO₂, the SiO bond of SiO₂, neighboring ZrO₄, became stronger and that the Brönsted acid site H which is located on the SiO₄ unit exhibits stronger acidity.     

Crystal orientation in a semicrystalline polymer in relation to deformation of polymer spherulites. IV. Crystal orientation mechanism of nylon-6 under uniaxial stretching

A model relating crystal orientation to the deformation of nylon-6 spherulites under uniaxial stretching is discussed in terms of the orientation distribution functions of reciprocal lattice vectors of crystal planes, such as the (002) and (200) planes. The distribution functions calculated from the model are compared with those obtained from x-ray diffraction experiments. It is found that the crystal a axis and, consequently, the direction of hydrogen bonds within the crystal (α modification) orient parallel to the lamellar axis in the undeformed state, and that the crystal orientation behavior of nylon-6 is much different from that of low-density polyethylene, being characterized by much smaller values of the reorientation parameters of crystallites within orienting lamellae. Moreover, small-angle light scattering for H_v and V_v polarization is also calculated on the basis of the spherulite deformation model by taking the nylon-6 crystal as having orthogonal–biaxial symmetry in optical anisotropy. It is concluded that the H_v scattering can be realized in terms of the proposed model for spherulite deformation by taking into account a considerable contribution of hydrogen bonds to the molecular polarizability, so as to make the polarizability along the crystal a axis larger than that along the b axis. In other words, this conclusion suggests positively birefringent spherulites in the nylon-6 samples studied.     

Nonequilibrium thermodynamics in field theory: Transport coefficients

Transport coefficients are expressed by real time correlation functions of energy-momentum tensor in the linear response approximation. We establish field theoretical method to compute them in perturbation theory, which is demonstrated in λ?⁴ theory.     

A quantitative analysis of the through-space and the through-bond interactions between lone-pairs and σ-frames: S-triazine and S-tetrazine

The CNDO/2 and INDO calculations were performed on s-triazine and s-tetrazine. The s-triazine has three lone-pairs in a molecule, and these can be combined into three combinations, A, n_s and n_A. Among the three, n_s and n_A are degenerated when the whole interaction conserves its molecular point symmetry, D_3h. The s-tetrazine has four lone-pairs, which can be transformed into four combinations, SS,SA, AS and AA. The energies of these orbitals show interesting behavior. The results were subjected to an analysis from the standpoint of the through-space and through-bond interactions using the localized molecular orbitals. As a result of these analyses, the interactions were expressed by several interaction terms.     

Theoretical prediction of maxima in association constants for complex formation between flavin mononucleotide and indoleacetate in the presence of polyelectrolytes

The effects of ionene polymers (6,3-ionene, 6,6-ionene, 6,8-ionene, and 6,12-ionene) with various charge densities upon association constants K for the complexation between flavin mononucleotide and indoleacetate have been studied. Except for 6,12-ionene, K increases with increasing polymer concentration then passes through a maximum, and declines at high polymer concentrations. The value of the maximum K increases in the order 6,8-ionene > 6,3-ionene > 6,6-ionene. In contrast, 6,12-ionene gives only a monotone increasing curve with increasing polymer concentration. These curves are analyzed using the theory of the partition coefficient proposed in the previous paper. The types of the curves that the theory predicts are classified in greater detail than in the previous paper, and examples are given. © 1993 John Wiley & Sons, Inc.     

A light-scattering study of deformation of liquid-crystalline spherulites of poly(γ-benzyl-L-glutamate) in an electric field

The deformation of liquid-crystalline spherulites of poly(γ-benzyl-L -glutamate) (PBLG) in an electric field was investigated by light scattering, polarized-light microscopy, and birefringence measurements. Under the polarizing microscope, the deformation was found to be dependent upon the field strength. The spherulites deformed perpendicular to the field. Above 75 V/cm in N,N-dimethylformamide or 120 V/cm in 1,1,2-trichloroethane, the deformed spherulites were transformed to rodlike textures. With increasing voltage, the rods gradually oriented parallel to the electric field. On the basis of the experimental results, models for affine deformation are proposed. With these models, light-scattering patterns are calculated. The calculated and experimental patterns agree semiquantitatively.