Metal-Support Interaction and Catalysis of the Catalysts Prepared Using Microemulsion

We have developed a new preparation method (ME method) of supported metal catalysts by using microemulsion. The metal particles in the catalyst prepared by this method were interacted strongly with support and were considered to be positively charged, and the SiO₂-supported Rh and Fe catalysts prepared by this method exhibited a unique activity and a good selectivity to oxygenates in the hydrogenation of CO. The Al₂O₃-supported Ni catalyst also exhibited an excellent activity and a strong resistance to carbon deposition in the methane-steam reforming. In this review, these interesting catalytic behaviors of the catalysts prepared by ME method were elucidated from the view-point of the electronic state of metals.     

Metabolic engineering of Saccharomyces cerevisiae for efficient production of pure l ?(+)?lactic acid

We developed a metabolically engineered Saccharomyces cerevisiae, which produces optically pure l-lactic acid efficiently using cane juice-based medium. In this recombinant, the coding region of pyruvate decarboxylase (PDC)1 was completely deleted, and six copies of the bovine l-lactate dehydrogenase (l-LDH) genes were introduced on the genome under the control of the PDC1 promoter. To confirm optically pure lactate production in lowcost medium, cane juice-based medium was used in fermentation with neutralizing conditions. l-lactate production reached 122 g/L, with 61% of sugar being transformed into l-lactate finally. The optical purity of this l-lactate, that affects the physical characteristics of poly-l-lactic acid, was extremely high, 99.9% or over. These two authors contributed equally to this work.     

Micelle-vesicle transition of oleyldimethylamine oxide in water

We studied the effects of the degree of ionization() and the surfactant concentration (C_d) on the micelle–vesicle transition in salt-free oleyldimethylamine oxide (OlDMAO) aqueous solutions by the dynamic light scattering (DLS), the hydrogen ion titration, the small angle neutron scattering (SANS), the electrophoretic light scattering (ELS) and viscoelastic measurements. From the study of ionization effects, the micelle–vesicle transition was recognized as a change of aggregate size by the DLS measurement; however, the micelle–vesicle transition was not detected both in the ELS measurement and the hydrogen ion titration, suggesting that the electric properties of the worm-like micelles and the vesicles are very similar despite a large difference of shapes between them. From the results of the SANS, the DLS and the viscosity measurements, it was suggested that a concentration-dependent micelle–vesicle transition took place around C_p = 10 mmol kg⁻¹ for the solutions at = 0.5. In the concentration-range 10 mmol kg⁻¹ < C_d < 150 mmol kg⁻¹, the micelles and the vesicles coexisted. In the concentration region (C_d = 10–50 mmol kg⁻¹), the vesicle size increased with the surfactant concentration.     

The absolute configuration of the side chain diol moiety of the poison-frog alkaloid pumiliotoxin B

The absolute configuration of the diol moiety in the side chain of pumiliotoxin B has been established by comparison of the ozonolysis product from pumiliotoxin B diacetate with the synthetic 3,4-diacetoxy-2-pentanone derived from L-(+)-tartaric acid. This indicates the absolute configuration (R, R) of C-15, C-16 diol of pumiliotoxin B.     

Thermodynamic evaluation of antibacterial activity for inclusion complexes of amoxicillin with cyclodextrins

The antibacterial action of amoxicillin (AMPC) and the inclusion complexes of AMPC with α-, β- and γ-cyclodextrins (α-CD, β-CD and γ-CD, respectively) to Escherichia coli B (E. coli) was evaluated by isothermal titration microcalorimetry and by petri-dish bioassay method. The effects of the compounds on produced heat during the exponential phase of the E. coli growing were measured and the growing rate constants of the cells was calculated from the power-time (p-t) curve before and after the treatment with AMPC. Results from the both methods showed that the antibacterial activity became stronger in the following order: AMPC-βCD > AMPC-γCD ≈ AMPC-αCD > AMPC only.     

Observation of adducts in the reaction of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) using cavity ring-down spectroscopy

The reactions of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) have been studied using cavity ring-down spectroscopy in 25-125 Torr total pressure of N2 diluent at 250 K. Formation of the XCH2I-Cl adduct is the dominant channel in all reactions. The visible absorption spectrum of the XCH2I-Cl adduct was recorded at 405-632 nm. Absorption cross-sections at 435 nm are as follows (in units of 10(-18) cm2 molecule(-1)): 12 for CH3I, 21 for CH3CH2I, 3.7 for CH2ICl, 7.1 for CH2IBr, and 3.7 for CH2I2. Rate constants for the reaction of Cl with CH3I were determined from rise profiles of the CH3I-Cl adduct. k(Cl + CH3I) increases from (0.4 +/- 0.1) x 10(-11) at 25 Torr to (2.0 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1) at 125 Torr of N2 diluent. There is no discernible reaction of the CH3I-Cl adduct with 5-10 Torr of O2. Evidence for the formation of an adduct following the reaction of Cl atoms with CF3I and CH3Br was sought but not found. Absorption attributable to the formation of the XCH2I-Cl adduct following the reaction of Cl atoms with XCH2I (X = H, CH3, Br, I) was measured as a function of temperature over the range 250-320 K.     

Ozone Degradation by Fluoride onto Plasma-Treated Activated Carbon in CF4

The ozone degradation of fluorine was investigated using the tetrafluoromethane plasma-treated activated carbon (PT-AC). The ozone in the stratosphere has been degraded by the chloride and bromide radicals which are produced from chlorofluorocarbons and bromofluorocarbons, respectively. However, we believe that fluorine also was related to the ozone degradation. The fluoride was introduced onto the activated carbon surface by tetrafluoromethane plasma treatment. The breakthrough curve of ozone onto PT-AC was measured to elucidate the relationship between the ozone and the fluoride. The amount of ozone adsorbed/degraded onto the PT-AC was larger than the amount that was adsorbed/degraded onto the untreated activated carbon. The amount of fluoride ion eluted from the PT-AC before the adsorption/degradation of ozone was larger than that which eluted after the adsorption/degradation of ozone. These results indicated that the ozone was degraded by the fluoride on the PT-AC surface.