Hydroquinone oxidation catalyzed by pyridine–Cu(II) complexes attached to polyorganosiloxane. II. Elucidation of factors related to catalytic activity

The oxidation of hydroquinone catalyzed by pyridine-Cu(II) complexes attached to polyorganosiloxane was investigated in the mixed solvent of methanol/water (vol. ratio 2/1). The catalytic oxidation followed Michaelis-Menten-like kinetics. The large k₂ term related to a turnover number indicated that the present polymeric catalysts have a remarkable effect on the activation process. The methylene number between the side-chain acid amido and pyridyl groups of the polymeric ligand was shown to be closely related to the appearance of hydrophobic effects in both the substrate-binding and the activation processes as deduced from the Michaelis constant and the thermodynamic and activation parameters. The binding parameters for 4-methoxyphenol with pyridyl-functionalized polyorganosiloxanes supported that the flexible backbone is also effective in the oxidation of hydroquinone. The Cu(II) complexes with pyridyl-functionalized polyorganosiloxane would have the structures distorted from square planar formation, which would promote the reduction of Cu(II) to Cu(I), as concluded from ESR spectroscopy and electrochemical measurement. © 1994 John Wiley & Sons, Inc.     

Treatment of ion exchange membranes to decrease divalent ion permeability

In the electrodialysis process for concentrating sea water, the addition of a small amount of the polycationic reagent Nonisold into the sea water feed results in a reduction of divalent cation permeability relative to that of monovalent cations. This is due to the formation of a reagent layer on the surface of the cation-exchange membrane. Divalent cations require greater energy to pass over the potential barrier at the reagent layer than do monovalent cations. The relationship between the height of the potential barrier and the ratio of ionic fluxes or the permselectivity coefficient is deduced on the basis of a kinetic-controlled mechanism of uptake of ions from the solution, and the height of the potential barrier is estimated from the experimental results. The difference between the potential barrier for divalent cations and that for monovalent cations may reach up to about 10 kJ/mol.     

High-speed gel-permeation chromatography

To establish optimum operating conditions for high-speed gel-permeation chromatography (GPC), the effects of column packing particle size, solvent flow rate, and column length on the separation efficiency have been investigated by using monodisperse polystyrene samples and polystyrene gel columns (TSK-GEL column, Type-H). Decreasing the particle size of the column packing reduces the time required to obtain a given resolution. Monodisperse polystyrene standards were measured under the optimum operating conditions established (gel particle size 5 μ, column length 2 ft, flow rate 2.5 ml/min). The molecular weight distribution of a polymer mixture was determined in less than 10 min with the same accuracy as by the conventional GPC. Such short analysis time enables one to use GPC for in-plant quality control.     

Some new consistency relations connecting spline values at mesh and mid points

This paper is concerned with polynomial splines on a uniform mesh. Linear dependence relations connecting spline values at mesh and mid points are developed.     

A class of plastic constitutive equations with vertex effect—IV. Applications to prediction of forming limit strains of metal sheets under nonproportional loadings

The new plastic (elastoplastic) constitutive equation with vertex effect which was proposed and developed in the previous papers is applied to prediction of the forming limit strains of metal sheets which are subjected to various nonproportional loading without unloading and to proportional loading after another proportional loading with or without unloading. It is demonstrated that the constitutive equation is very effective, that appropriately curved strain-paths give much larger limiting strains than the corresponding straight paths do, that abrupt change in stress- or strain-path very often induces a catastrophic breakage at the instant of the path-change, and that very useful secondary FLDs (forming limit diagrams) can be drawn.     

The isolation and structure elucidation of new cassane diterpene-acids from Caesalpinia crista L. (Fabaceae), and review on the nomenclature of some Caesalpinia species

New cassane diterpene-acids, neocaesalpins H and I, were isolated from the leaves of Caesalpinia crista (Fabaceae), and their structures were deduced on the basis of the spectroscopic and chemical basis. These compounds were characterized as having an alpha,beta-butenolide hemiacetal ring that is rare in nature. The lacking of 5-hydroxy group also distinguished neocaesalpins H and I from cassane diterpenes (caesalpins) occurring in other Caesalpinia species from the phytochemical viewpoint. The nomenclature of three Caesalpinia species was also reviewed, and it was found that some species belonging to the genus Caesalpinia are improperly named and should be changed to valid names.     

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.     

Some propositions on caustics and an application to the biaxial-fracture problem

Some fundamental problems on the optical method of caustics, which is used to determine the value of the stress-intensity factor, are studied. The paper shows that the radiusr _o of the initial curve considerably affects the results and describes a method to eliminate this effect. This method is also applied to the biaxial-stress fracture problem. It is shown that the biaxial stress affects the fracture toughness of thin specimens of Plexiglas sheets and that the fatigue-crack-growth rate is increased due to the compressive stress along the crack line.Paper was presented at 1982 SESA/JSME Spring Meeting held in Oahu and Maui, HI on May 23–29, 1982.     

X-ray photoelectron spectra of ylide—TCNQ charge-transfer complexes

Charge-transfer complexes of TCNQ with ylides, new-type donors, were synthesized and the X-ray photoelectron spectra of these complexes were measured. A broad satellite caused by TCNQ radicals observed.