Epitaxial growth of titanium oxide thin films on MgO(100) single-crystal substrates by reactive deposition methods

We synthesized titanium oxide thin films on MgO(100) single-crystal substrates by two reactive deposition methods and compared the structures of the thin films formed by these methods. In one method (pulsed-molecular-beam deposition method), molecular oxygen is supplied to the substrates by using a pulsed-molecular-oxygen beam source and deposition of one unit layer of titanium and subsequent supply of molecular oxygen are repeatedly performed. In the other method (radical beam deposition method), atomic oxygen is irradiated to the substrates by using an atomic oxygen beam generated by the radical beam source and irradiation of the atomic oxygen and deposition of titanium are simultaneously performed. In the case of the pulsed-molecular-beam deposition method, the crystal structure was changed by increasing the number of oxygen pulses supplied from the beam source. We found that the crystal structure of titanium oxide depended on the composition ratio of O:Ti in the film. The maximum ratio of O:Ti attainable by this method was 1.85, and at this ratio, (100)-oriented pseudorutile was formed. In the case of the radical beam deposition method, (100)-oriented anatase was formed below the titanium deposition rate of 0.10 nm/s and pseudorutile (TiO_2−δ) was formed above 0.15 nm/s. The pseudorutile structure synthesized on this experiment was very stable in air. We concluded that the crystal structure of the pseudorutile is a new crystal structure of titanium oxide.     

Catalytic decomposition of N2O over supported rhodium catalysts: high activities of Rh/USY and Rh/Al2O3 and the effect of Rh precursors

The catalytic decomposition of nitrous oxide to nitrogen and oxygen has been studied over Al₂O₃-supported and zeolite-supported Rh catalysts. The activities of Rh/Al₂O₃ and Rh/USY (ultrastable Y zeolite) catalysts prepared from Rh(NO₃)₃ were higher than those of Rh/ZSM-5 and Rh/ZnO reported in the literature, while the activity of a Rh/Al₂O₃ catalyst prepared from RhCl₃ was suppressed severely in spite of the high H/Rh and CO/Rh values. The catalytic activity of N₂O decomposition was sensitive not only to the Rh dispersion but also to the preparation variables such as the Rh precursors and the supports used. This revised version was published online in July 2006 with corrections to the Cover Date.     

The dynamics of CO oxidation on Pt(110) studied by infrared chemiluminescence of the product CO2: effect of CO coverage

The infrared chemiluminescence technique has been applied to the catalytic oxidation of CO on a Pt(110)(1×2) surface. The vibrational and the rotational states of CO₂ formed on the reconstructed Pt(110)(1×2) surface are more excited than those on the terrace Pt(111) surface. The vibrational state of the product CO₂ strongly depends on the CO coverage: the vibrational temperature (T_V) of the product CO₂ becomes higher, as the coverage of CO increases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Creation of functional materials by use of a slow crystallization process in the nonequilibrium state. I. porous polyamide microparticles

Recently a number of investigations have focused on the self‐organization process from the nonequilibrium state as a new technique that may be used to develop many functional materials. In many cases, amorphous polymers were used and semicrystalline polymers were seldom used in spite of their importance. In this study, we basically investigated the crystal structure, crystalline process, and inner structures of polyamide by using slow phase separation and crystallization process from the nonequilibrium state of the polymer solution. We were able to observe the crystalline lamella growing twisted from the center of the particle. Between these lamella layers, narrow pores were created. From this investigation, we developed a new method to create functional materials of polyamide, the semicrystalline polymer. Porous spherical particles may be properly applied to functional materials such as adsorption materials, catalyst support materials, and so on. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2428–2432, 2003     

Novel Route to Propylene Carbonate: Selective Synthesis from Propylene Glycol and Carbon Dioxide

High surface area zirconium phosphate in an amorphous phase exhibits high activities for water-related reactions such as hydrolysis of ethyl acetate and esterification of acetic acid with ethanol. The zirconium phosphate is insoluble during the reaction, is recoverable by simple filtration, and can be reused at least five times without any treatment.     

Catalytic performance of Ni/CeO2/Al2O3 modified with noble metals in steam gasification of biomass

In the steam gasification of biomass, the additive effect of noble metals such as Pt, Pd, Rh and Ru to the Ni/CeO₂/Al₂O₃ catalyst was investigated. Among these noble metals, the addition of Pt was most effective even when the loading amount of added Pt was as small as 0.01 wt.%. In addition, the catalyst characterization suggests the formation of the Pt–Ni alloy over the Pt/Ni/CeO₂/Al₂O₃.     

Catalytic performance and characterization of Pt-Ni bimetallic catalysts for oxidative steam reforming of methane

Effects of methane oxygen mixture addition to steam reforming of methane and subsequent removal of the methane oxygen mixture from the oxidative steam reforming of methane on catalytic performance were investigated using monometallic Ni and Pt catalysts and two Pt-Ni bimetallic catalysts. Hysteresis with respect to the addition and removal of the methane oxygen mixture was observed clearly on a Pt-Ni bimetallic catalyst prepared by co-impregnation method and the Ni catalyst. In contrast, no hysteresis was observed for a Pt-Ni catalyst that was prepared by sequential impregnation method. Combined with characterization results obtained using EXAFS analysis and FTIR of CO adsorption, Pt-Ni catalyst was prepared by sequential impregnation is formed Pt-Ni alloy particles, where Pt atoms are segregated on the surface, enhances the reducibility of Ni drastically and this is related to the behavior without hysteresis.     

Catalyst Design of Pt-Modified Ni/Al2O3 Catalyst with Flat Temperature Profile in Methane Reforming with CO2 and O2

Pt(0.3)/Ni(10)/Al₂O₃, prepared by a sequential impregnation method, exhibited a more excellent performance in methane reforming with CO₂ and O₂ in terms of the catalytic activity and the temperature profile of the catalyst bed than Pt(0.3) + Ni(10)/Al₂O₃ prepared by a coimpregnation method, Ni(10)/Al₂O₃, Pt(0.3)/Al₂O₃, and Pt(10)/Al₂O₃. It is thought that this is because the surface Pt atoms on Ni catalyst can contribute to the enhancement of the catalyst reducibility.     

Dietary eritadenine-induced alteration of molecular species composition of phospholipids in rats

The effect of dietary eritadenine, a hypocholesterolemic compound found in the mushroomLentinus edodes, on the fatty acid and molecular species profiles of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in the plasma and liver microsomes was investigated in relation to the hypocholesterolemic action of the compound in rats. Animals were fed the control or eritadenine-supplemented (50 mg/kg diet) diet for 14 d. Eritadenine supplementation significantly decreased the plasma concentrations of cholesterol and phospholipids, but not triglycerides. The PC/PE ratio of liver microsomes, but not plasma, was also markedly decreased by eritadenine. Eritadenine supplementation was found to increase the proportion of 18:2n-6 and, inversely, to decrease the proportion of 20:4n-6 and 22:5n-6 in plasma PC and liver microsomal PC and PE, indicating that eritadenine depressed the metabolism of linoleic acid. The effect of eritadenine on the profile of n-3 fatty acids was dissimilar in PC and PE. These changes in fatty acid composition were selectively reflected in the molecular species composition of both PC and PE; the extent of increase in 16:0–18:2 molecular species or decrease in 18:0–20:4 molecular species was apparently greater than that of other molecular species containing 18:2 or 20:4 in the sn-2 position. These results suggest that, in addition to the decrease in liver microsomal PC/PE ratio, the alteration of plasma PC molecular species composition might also participate in the hypocholesterolemic action of eritadenine.