Chemo-biological preparation of the chiral building block (R)-4-acetoxy-2-methyl-1-butanol using Pseudomonas putida

In order to develop new methyl substituted chiral building blocks which are useful for the synthesis of methyl branched natural products, the enantioselective bioreduction of an exo-methylene to a methyl group was investigated. 4-Acetoxy-2-methylene-1-butanol 3 was prepared from itaconic acid over four steps and converted to the chiral alcohol (R)-4-acetoxy-2-methyl-1-butanol 4, by growing cells of Pseudomonas putida. The bioconversion achieved a high enantioselectivity (92% ee) and a high chemical yield (65%) within a relatively short reaction time (18–20 h).     

Evaluation of electron-hole recombination properties of titanium (IV) oxide particles with high photocatalytic activity

Electron-hole recombination in nano-sized titanium(IV) oxide (TiO₂) particles with various physical properties, which have been shown to be highly active photocatalysts, was evaluated by quantitative analysis of reduced titanium species (Ti³⁺), which might be formed at crystalline defective sites in TiO₂ particles through photo-irradiation in the presence of a hole scavenger under deaerated conditions. These highly active photocatalyst samples were synthesized by hydrothermal crystallization in organic media (HyCOM method) and post-calcination. The Ti³⁺ density decreased with increasing calcination temperature (T _c), and a linear correlation was observed between the Ti³⁺ density and rate constant for electron-hole recombination evaluated by femtosecond pump-probe diffuse reflection spectroscopy. Reaction rate (R _Ag) and the amount of silver ions (Ag⁺) adsorbed on TiO₂ particles ([Ag⁺]_ads) were measured for photocatalytic silver metal deposition along with oxygen formation from an aqueous Ag⁺ solution under deaerated conditions, and the slope of the R _Ag versus [Ag⁺]_ads plot was determined. Kinetic investigation of this reaction showed that the reciprocal of the slope was approximately related to the ratio of the rates for electron-hole recombination and electron trapping (k _r/k _e ratio). The k _r/k _e ratio decreased as T _c increased, and the logarithm of the k _r/k _e ratio was linearly related with Ti³⁺ density. These two parameters were used as a measure for the recombination properties of TiO₂ photocatalysts with various physical properties.     

铜离子交换分子筛上NO吸附的IR光谱及TPD研究

采用原位IR光谱及TPD技术研究了NO在铜离子交换分子筛上各种表面物种的生成及脱附,并与NO在Cu-ZSM-5上的分解反应性能相关联,考察了Cu-ZSM-5反应活性高的原因及O₂的生成机理。NO的吸附状态随分子筛母体种类及铜离子交换度的不同而变化,交换度较高的ZSM-5催化剂上容易形成NO-3物种,该物种对NO分解及O₂的生成具有重要作用。     

Non-parametric kernel regression for multinomial data

This paper presents a kernel smoothing method for multinomial regression. A class of estimators of the regression functions is constructed by minimizing a localized power-divergence measure. These estimators include the bandwidth and a single parameter originating in the power-divergence measure as smoothing parameters. An asymptotic theory for the estimators is developed and the bias-adjusted estimators are obtained. A data-based algorithm for selecting the smoothing parameters is also proposed. Simulation results reveal that the proposed algorithm works efficiently.     

An explicit formula for Koecher-Maaß Dirichlet series for Eisenstein series of Klingen type

We give a reasonable expression of the Koecher-Maaß Dirichlet series for the Klingen-Eisenstein lift of an elliptic cusp form.