Modeling strain hardening of polydisperse polystyrene melts by molecular stress function theory

The strain hardening of blends of polystyrene (PS) and ultra-high molecular weight polystyrene (UHMW-PS) in elongational flow is modeled by the molecular stress function (MSF) theory. Assuming that the ratios of strain energies stored in polydisperse and monodisperse polymers are identical for linear and nonlinear deformations, the value of the only non-linear parameter of the theory in extensional flows, the maximum molecular stress f_max, can be determined and is shown to be related to steady-state compliance J_e0. Using only linear-viscoelastic data, the elongational viscosity of PS/UHMW-PS blends is consistently predicted by the MSF theory.     

Electronic coupling calculation and pathway analysis of electron transfer reaction using ab initio fragment-based method. I. FMO-LCMO approach

By making use of an ab initio fragment-based electronic structure method, fragment molecular orbital-linear combination of MOs of the fragments (FMO-LCMO), developed by Tsuneyuki et al. [Chem. Phys. Lett. 476, 104 (2009)], we propose a novel approach to describe long-distance electron transfer (ET) in large system. The FMO-LCMO method produces one-electron Hamiltonian of whole system using the output of the FMO calculation with computational cost much lower than conventional all-electron calculations. Diagonalizing the FMO-LCMO Hamiltonian matrix, the molecular orbitals (MOs) of the whole system can be described by the LCMOs. In our approach, electronic coupling T(DA) of ET is calculated from the energy splitting of the frontier MOs of whole system or perturbation method in terms of the FMO-LCMO Hamiltonian matrix. Moreover, taking into account only the valence MOs of the fragments, we can considerably reduce computational cost to evaluate T(DA). Our approach was tested on four different kinds of model ET systems with non-covalent stacks of methane, non-covalent stacks of benzene, trans-alkanes, and alanine polypeptides as their bridge molecules, respectively. As a result, it reproduced reasonable T(DA) for all cases compared to the reference all-electron calculations. Furthermore, the tunneling pathway at fragment-based resolution was obtained from the tunneling current method with the FMO-LCMO Hamiltonian matrix.     

Synthesis and oxygen permeation properties of 75 mol% Ce0.75Nd0.25O1.875–25 mol% Nd1.8Ce0.2CuO4 composite

An oxygen-permeable composite constituted to oxide ionic conductor phase (Ce_0.75Nd_0.25O_1.875) and oxide electronic conductor phase (Nd_1.8Ce_0.2CuO₄) was prepared using the acetate pyrolysis method. Based on electrical conductivity measurements, total electrical conductivity of 75 mol% Ce_0.75Nd_0.25O_1.875–25 mol% Nd_1.8Ce_0.2CuO₄ composite material was governed by the electronic conduction paths. With respect to the oxygen permeation properties, the results showed that oxygen permeation properties were unexplainable by a simple composite rule using the electrical transport properties of the bulk Ce_0.75Nd_0.25O_1.875 and the bulk Nd_1.8Ce_0.2CuO₄.     

Algebraic Independence of Reciprocal Sums of Binary Recurrences II

 Algebraic independence of the numbers for various d and l, where is a periodic sequence of algebraic numbers and is a sequence of integers satisfying a binary linear recurrence relation, is studied by Mahler’s method. Received 25 August 2000; in revised form 8 January 2002     

Microscopic characterisation of self-assembled colloidal particles in electrohydrodynamic convection of a low-birefringence nematic liquid crystal

Electrokinetics of small particles immersed in anisotropic fluids is attracting attention in recent years. Here we focus on microscopic appearance of single as well as self-assembled particles moving in the electrohydrodynamic convection (EHC) of a nematic liquid crystal with low birefringence. Characterisation of the birefringent properties is made by polarised light microscopy under different illumination conditions. Because of the small optical anisotropy, the director distortion around the particles clearly exhibits distinctive colours on both sides depending on the height in the cell. The observation can be explained as the change in the net phase retardation of the light. It is also found that a caterpillar-like motion is possible by tuning temperature, although the horizontal size of the EHC rolls is relatively narrow.     

Photochemical reactions of ketones to synthesize gold nanorods

Photochemical synthesis of gold nanorods (NRs) in a micellar solution of hexadecyltrimethylammonium bromide (CTAB) was triggered by photoreactions of ketones. Photoexcitation of gold ions and silver bromide clusters ((AgBr)n) in the absence of ketones did not produce NRs. The initial products of the photoirradiation were probably ketyl radicals, which then initiated reactions to form NRs. NRs formed in darkness, if the reaction solutions were irradiated by UV light for a few minutes, thus indicating that the photochemical products catalyzed NR-formation.     

Carbon-sulfur bond cleavage reactions of dibenzothiophene derivatives mediated by iron and ruthenium carbonyls

A thermal reaction of 6-(4'-dibenzothienyl)-2,2'-bipyridine (bpyDBT) with [Ru(3)(CO)(12)] produced a sulfur-bridged triruthenium complex via double carbon-sulfur bond cleavage and CO insertion, while a diiron(I,I) complex containing a thiametallacycle was obtained by a photochemical reaction of bpyDBT with [Fe(CO)(5)].