Diffusion Coefficients of Tris(<Emphasis Type="Italic">β</Emphasis>-diketonato)ruthenium Complexes of Different Charge Numbers in Acetonitrile Solutions,Measured by Chronoamperometry

The diffusion coefficients of several tris(β-diketonato) ruthenium complexes in acetonitrile solutions containing a supporting electrolyte were determined by chronoamperometry. The diffusion coefficients of the charged complexes, which were produced by electrochemical oxidation or reduction, were also determined by double potential step chronoamperometry. Two kinds of radii of the complexes were evaluated. One was the Van der Waals radius and the other was the geometric distance from the center of the complex to the outer surface of the farthest atom. The latter quantity was determined from X-ray diffractometric data. The diffusion coefficients of the neutral complexes were discussed on the basis of the Stokes-Einstein equation. Those of charged complexes could not be explained by the theoretical equation presented by Hubbard and Onsager.     

Polymer electrolytes plasticized with hyperbranched polymer for lithium polymer batteries

Hyperbranched polymers (HBPs) with different terminal groups and different ethylene oxide (EO) chain lengths were prepared, and the influence of the HBP structures including molecular weights and molecular weight distribution on the ionic conductivity and the mechanical property of the composite polymer electrolytes composed of poly (ethylene oxide) (PEO), HBP, BaTiO₃ as a ceramic filler, and LiN(CF₃SO₂)₂ as a lithium salt were investigated. It was found that the molecular weights of the HBP do not affect significantly the ionic conductivity, but the molecular weight distribution might affect it, and also further branching at the terminals of the HBP led to a decrease in the ionic conductivity. The HBP with longer EO chain length was effective for enhancement of the ionic conductivity in comparison with the HBP with shorter one. The increase in cross-linkable groups (acryloyl group) at the terminals of the HBP improved the tensile strength, but caused the ionic conductivity to decrease. Loosely cross-linked composite polymer electrolyte showed higher ionic conductivity and higher tensile strength than no cross-linked one. Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 – 18, 2004.     

Elementary reaction analysis of the radical polymerization of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups

The polymerizations of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups (RS‐EMBI and S‐EMBI) with dimethyl 2,2′‐azobisisobutyrate (MAIB) were studied in methanol (MeOH) and in benzene kinetically and with electron spin resonance (ESR) spectroscopy. The initial polymerization rate (R_p) at 60 °C was given by R_p = k[MAIB]^{0.58 ± 0.05}[RS‐EMBI]^{2.4 ± 0.l} and R_p = k[MAIB]^{0.61 ± 0.05}[S‐EMBI]^{2.3 ± 0.l} in MeOH and R_p = k[MAIB]^{0.54 ± 0.05}[RS‐EMBI]^{1.7 ± 0.l} in benzene. The rate constants of initiation (k_df), propagation (k_p), and termination (k_t) as elementary reactions were estimated by ESR, where k_d is the rate constant of MAIB decomposition and f is the initiator efficiency. The k_p values of RS‐EMBI (0.50–1.27 L/mol s) and S‐EMBI (0.42–1.32 L/mol s) in MeOH increased with increasing monomer concentrations, whereas the k_t values (0.20?7.78 × 10⁵ L/mol s for RS‐EMBI and 0.18?6.27 × 10⁵ L/mol s for S‐EMBI) decreased with increasing monomer concentrations. Such relations of R_p with k_p and k_t were responsible for the unusually high dependence of R_p on the monomer concentration. The activation energies of the elementary reactions were also determined from the values of k_df, k_p, and k_t at different temperatures. R_p and k_p of RS‐EMBI and S‐EMBI in benzene were considerably higher than those in MeOH. R_p of RS‐EMBI was somewhat higher than that of S‐EMBI in both MeOH and benzene. Such effects of the kinds of solvents and monomers on R_p were explicable in terms of the different monomer associations, as analyzed by ¹H NMR. The copolymerization of RS‐EMBI with styrene was examined at 60 °C in benzene. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1819–1830, 2003     

On some slowly convergent series involving the Hurwitz zeta-function

We shall extract the essence of the Adamchik–Srivastava generating function method (Analysis (Munich) 18 (1998) 131) by proving the most far-reaching Ramanujan–Yoshimoto formula and by showing that some of the results stated in Srivastava and Choi (Series Associated with the Zeta and Related Functions, Kluwer Academic Publishers, Dordrecht, 2001) are simple consequences of the above-mentioned formula.     

Synthetic studies of carzinophilin. Part 1: Synthesis of 2-methylidene-1-azabicyclo[3.1.0]hexane systems related to carzinophilin

Synthesis of the model compounds of carzinophilin carrying 2-methylidene-1-aza-bicyclo[3.1.0]hexane systems was achieved. Formation of malonylidenes or N-acyl-glycinylidenepyrrolidines was carried out by utilizing Eschenmoser's sulfide contraction or Herdeis's condensation between the 2-methylthio-Δ¹-pyrrolone derivatives and ethyl nitroacetate, respectively. The 1-azabicyclo-[3.1.0]hexane systems were constructed by base-promoted aziridine formation.     

Stereochemistry of reduction of the C-24,25 double bond in the conversion of desmosterol into cholesterol

Feeding of the chemically prepared [24-¹³C, 24-²H]desmosterol to cell-free systems derived from rat liver and silkworm gut and to cultured cells of Oryza sativa followed by deuterium-decoupled ¹H, ¹³C shift correlation NMR analysis of the biosynthesized cholesterol revealed the stereospecific incorporation of hydrogen atoms from the re-face of the C-24 position of desmosterol.     

Cohaerins C-F, four azaphilones from the xylariaceous fungus Annulohypoxylon cohaerens

Four azaphilones named cohaerins C-F, along with 4,5,4′,5′-tetrahydroxy-1,1′-binaphthyl were isolated from the methanolic extract of the stromata of Annulohypoxylon cohaerens (Ascomycetes, Xylariaceae). Cohaerins C-E constitute typical azaphilones, bearing a γ-lactone ring, while cohaerin F has an unprecedented carbon skeleton, lacking the lactone ring of the azaphilones and with an aliphatic side chain being attached directly to the azaphilone backbone by a C-C bond. Their structures were determined by 2D NMR, IR, UV, and CD spectroscopy. They showed moderate inhibitory activity of nitric oxide production in RAW cells, and strong and nonselective antimicrobial effects.     

On generic families of cyclic polynomials with even degree

 We construct generic cyclic polynomials of even degree with two parameters. Our result, which is based on an affirmative solution for linear Noether's problem, corresponds to ``two-dimensional' Kummer theory with base field descended to the maximal real subfield of the cyclotomic field. Received: 17 September 2001 / Revised version: 31 October 2001     

On type numbers of split orders of definite quaternion algebras

In this paper, we shall give a new relation between the arithmetic of quaternion algebras and modular forms; we shall express the type numberT _{q, N} of a split order of type (q, N) as the sums of dimensions of some subspaces of the space of cusp forms of weight 2 with respect to Γ₀(qN) which are common eigenspaces of Atkin-Lehner's involutions.     

Formulation for XPS spectral change of oxides by ion bombardment as a function of sputtering time

XPS measurement revealed that the original state of TiO₂ was changed to Ti₂O₃ and TiO by ion bombardment. TiO₂ decreased and Ti₂O₃ increased at the initial stage. TiO increased at a later stage than Ti₂O₃. Each of them saturated after enough sputtering time.A formulation was proposed in order to explain the change of XPS spectra for oxides as a function of ion sputtering time. This formulation was based on reaction equations that contain two reduction processes (from TiO₂ to Ti₂O₃ and from Ti₂O₃ to TiO), and sputtering effects. Using four fitting parameters (two reduction coefficients, sputtering yield and information depth), the present formula was fitted to the experimental results. The fitting results agree satisfactorily with the experimental results. The calculation shows that the reduction coefficient from TiO₂ to Ti₂O₃ is about ten times larger than that from Ti₂O₃ to TiO. This calculation predicts that surface composition of an oxide that is changed by ion bombardment will reach a different value depending on its bulk composition. Moreover, the present formulation can determine the chemical states of compounds changed by ion bombardment.