Preparation of Titania Containing Mixed Oxides and Their Catalytic Activities

Titania containing catalysts were prepared by conventional procedures (coprecipitation, hydrogel kneading and titania precipitation) and a complexing-agent assisted sol-gel method. The effect of preparation methods on their properties and catalytic activities in the oxidation of olefins and decomposition of cumene hydroperoxide were examined. The sol-gel method gave the best dispersion of titania. In contrast, with the kneading and titania precipitation method, titania formed crystalline particles. The sol-gel catalysts are more effective for epoxydation of olefins because of the high dispersibility of Ti in them. However, the most active catalysts in the decomposition of cumene hydroperoxide are kneading ones.     

Viscometric,light scattering,and size‐exclusion chromatography studies on the structural changes of aqueous poly(vinyl alcohol) induced by γ‐ray irradiation

The crosslinking processes of aqueous poly(vinyl alcohol) (PVA) by γ‐ray irradiation were studied by viscometry, dynamic and static light scattering (DLS and SLS), as well as size exclusion chromatography (SEC). Increases in the intrinsic viscosity ([η]), molecular weight (M_w), hydrodynamic radius (R_h), and radius of gyration (R_g), and a decrease in second virial coefficient (A₂) were observed after γ‐ray irradiation. However, both the values of [η] and A₂ for irradiated PVA fell below the data of unirradiated PVA solutions, suggesting a conformational change of PVA chains after γ‐ray irradiation. This structural change of PVA as a result of γ‐ray irradiation was also indicated by the decreases in R_g/R_h from 1.5 to 1.39 by SLS and DLS, and in Mark–Houwink exponent α_η from 0.54 to 0.26 by SEC‐Viscometry. The broadening of the M_w distribution (MWD) as indicated by the polydispersity index increased from 2.2 to 6.5 because of γ‐ray irradiation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 214–221, 2000     

Characteristics of highly charged ions produced at Kobe EBIS under modulated operation

The electron beam ion source (Kobe EBIS) has been developed to perform modification of surfaces using highly charged ions (HCIs) at the Kobe University, Japan. Recent study revealed that periodic intermission of electron beam improves charge state distribution of extracted ions. The period of intermission is in the order of 100 ms, and the width of beam-off time is 1 ms or less. This operational mode (pulse mode) makes it possible to produce Ar¹⁵⁺ to Ar¹⁷⁺ effectively, whereas the charge is limited less than 14+ under the ordinary operational mode with direct current (DC) electron beam. A spike of HCIs with a peak current in the order of nA is also observed at each moment of electron beam off. The measurement of the time evolution of Ar¹⁶⁺ intensity around the timing of mode change revealed that the intensity of extracted Ar¹⁶⁺ changes slowly after mode change with a time constant of few seconds.     

Electrochemical and spectroelectrochemical properties of manganese reconstituted myoglobin

Electrochemical and spectroelectrochemical properties of manganese(III) reconstituted myoglobin (Mn(III)–Mb) have been investigated. No redox wave of Mn(III)–Mb was observed at a highly hydrophilic indium oxide electrode on which rapid direct electron transfer of native myoglobin took place, suggesting the electron transfer reaction of Mn(III)–Mb at an indium oxide electrode is very slow. The rate constant of the chemical reduction of Mn(III)–Mb with dithionite was ca. 20 times smaller than that of native Mb. Using an optically transparent thin layer electrode (OTTLE) cell and Oxazine-170 perchlorate, 5,9-bis(diethylamino)-10-methyl-benzo[a]phenoxazonium perchlorate, as an electron transfer mediator, the redox potential for the Mn(III) Mn(II)–Mb couple was estimated to be −0.32 V versus Ag AgCl (sat. KCl) at 25°C.     

Weak interaction between inhibition peptides and a soluble receptor of fusion protein in the liquid phase.

Fluorescence polarization analysis (FPA) of a liquid-phase method was carried out with a glycosylphosphatidylinositol (GPI) anchored membrane receptor bone marrow stromal cell antigen 1 (BST-1, CD157) as a model receptor for medical screening. A soluble receptor, BST1-Fc, was prepared by fusing the extracellular domain of BST-1 and the Fc region of human immunoglobulin G (IgG). The binding curves of BST1-Fc with a fluorescently labeled ligand peptide, or its three derivatives, were developed using ordinary FPA in the liquid phase. The obtained dissociation constants (Kd) were comparable with those reported as measured with SPR of a solid-phase method, except for one derivative peptide with Kd larger than 7000 nM. Competitive FPA was carried out, and it was demonstrated that a very weak interaction, which would be difficult to detect with SPR or other solid-phase methods, could be analyzed with both ordinary and competitive FPA.     

Controllable shape selectivity based on highly ordered carbonyl and methyl groups in simple β-structural polypeptide on silica

Poly(l-alanine)-grafted porous silica (Sil-Ala₂₂) was prepared by polymerization of N-carboxyanhydride of l-alanine initiated by 3-aminopropylated silica. The retention behaviors of the column packed with Sil-Ala₂₂ were investigated by using alkylbenzenes and polycyclic aromatic hydrocarbons as injection samples in liquid chromatography. The Ala₂₂ phase was in a rigid β-form structure and thus provided specific interaction sites, which were derived from the highly ordered carbonyl and methyl groups. These interaction sites bring unique molecular-shape discriminations: molecular-length and non-planarity selectivity, which are controllable by altering organic solvent used as a part of mobile phase.