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.     

Coolant Wetting Simulation on Simplified Stator Coil Model by the Phase-Field Lattice Boltzmann Method

Stator coils of automobiles in operation generate heat and are cooled by coolant poured from above. The flow characteristic of the coolant depends on the coil structure, flow condition, solid–fluid interaction, and fluid property, which has not been clarified due to its complexities. Since straight coils are aligned and layered with an angle at the coolant-touchdown region, the coil structure is simplified to a horizontal square rod array referring to an actual coil size. To obtain the flow and wetting characteristics, two-phase fluid flow simulations are conducted by using the phase-field lattice Boltzmann method. First, the flow onto the single-layered rod array is discussed. The wetting area is affected both by the rod gap and the wettability, which is normalized by the gap and the averaged boundary layer thickness. Then, the flow onto the multi-layered rod arrays is investigated with different rod gaps. The top layer wetting becomes longitudinal due to the reduction of the flow advection by the second layer. The wetting area jumps up at the second layer and increases proportionally to the below layers. These become remarkable at the narrow rod gap case, and finally, the dimensionless wetting area is discussed at each layer.     

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.     

Self-Assembly of Nanometer-Sized Macrotricyclic Complexes from Ten Small Component Molecules

Nanometer-sized bowls: six metal centers and four tridentate ligands self-assemble in aqueous solution to give the macrotricycle 1 , which has approximate dimensions of 3×2×2 nm. Another macrocycle (not shown), obtained with a different ligand, is of similar size and topology but differs considerably from 1 in its host–guest behavior.     

Study of radical generated from coumarin dye-sensitized photo-initiator systems in high-speed photopolymer coating layers using laser flash photolysis

Radical generation from photoinitiation systems containing carbonylbiscoumarin dye with a radical-generating reagent, 3,3′-carbonylbis[7-(diethylamino)-2H-1-benzopyran-2-one] (KCD-DA), with 2,2′-bis(2-chloro-phenyl)-4,4′5,5′-tetraphenyl-1, 1′-bi-1H-imidazole (BI) in a poly(methyl methacrylate) film has been investigated by laser flash photolysis using a total reflection cell. Imidazolyl radical (Im·) was predominantly generated from carbonylbiscoumarin triplet-sensi-­tized decomposition of BI, the quantum yield, Φ^o_Im· of Im· at an infinite concentration of BI was measured, Φ^o_Im· = 1.3. The high quantum yield, Φ^o_Im·, implies an efficient KCD-DA triplet-sensitized photoinitiation system containing BI. Copyright © 1998 John Wiley & Sons, Ltd.