Breeding of high-pyruvate-producing Torulopsis glabrata and amino acid auxotrophic mutants

An efficient method for the isolation of pyruvate-producing mutants of Torulopsis glabrata IFO 0005 was established. On mutagenesis of the parent strain, mutants requiring polypeptone for complete growth were isolated. Seven mutants among one hundred auxotrophs produced higher concentrations of pyruvate than the parent strain. Among them, arginine (L-Arg) auxotrophic mutants and an isoleucine (L-Ile) and valine (L-Val) double auxotrophic mutant exhibited higher fermentative production of pyruvate from glucose than the parent strain. T. glabrata X-15 and X-17 required L-Arg for complete growth. T. glabrata X-68 absolutely required L-Ile and L-Val for complete growth. These three strains (X-15, X-17 and X-68) have more than 10% higher yields of pyruvate than the parent strain. Among them, the best strain regarding pyruvate productivity, T. glabrata X-15, accumulated 59.5 g/l free pyruvic acid (yield, 60.1%; conversion to pyruvic acid of added glucose in 43 h) on a 3-l jar-fermentor scale. This yield with strain X-15 represented a 12% increase compared to that obtained with the parent strain.     

Changes in Surface Property and Catalysis of Mesoporous Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> from Amorphous to Crystalline Pore Walls

Abstract  

The amorphous inorganic phase of an ordered amorphous mesoporous Nb₂O₅ with two dimensional hexagonal (2D-hex) structure was crystallized with maintaining the original well arranged porous structure. The difference in surface property between amorphous and crystalline Nb₂O₅ with similar ordered mesoporous structure was compared. It was found from water adsorption–desorption isotherms and observation by infrared (IR) spectroscopy that the amorphous sample was hydrophilic and that the surface OH groups were acidic. On the other hand, the OH groups on crystalline mesoporous Nb₂O₅ were non-acidic and inside the pores was less hydrophilic. The surface property was also compared by a catalytic reaction, oxidation of cyclohexe by an aqueous solution of H₂O₂. The high (95%) selectivity for 1,2-epoxycyclohexane was obtained at 40 °C for 2 h in methanol solvent over crystalline mesoporous Nb₂O₅ at 12% conversion, while amorphous mesoporous Nb₂O₅ showed high (68%) selectivity for 1,2-cyclohexanediol in acetonitrile solvent at 60 °C for 2 h at 22% conversion. The differences in selectivity and the optimal solvent between amorphous and crystalline samples were interpreted in terms of the acidic feature of surface OH groups and hydrophilicity. While similar selectivity was observed over non-porous crystalline Nb₂O₅, much higher conversion over crystalline mesoporous Nb₂O₅ was attained at the same surface area. Thus, an advantage of mesoporous structure is attributed to the higher contact time of molecules inside the pores to the catalyst surface than those outside the particles.     

日本の寒地，北海道の稲作限界地帯におけるもち米の米粒外観品質の年次間地域間差異とその発生要因(日语原文)

北海道でも最も冷涼な稲作地帯で生産されるもち米の外観品質を,栽培6地域で4カ年調査した。年次間では,障害型冷害危険期の平均気温と出穂後40日間の日平均積算気温（登熟気温）が高いほど,不稔歩合が低く千粒重が重く多収で,整粒歩合が高く未熟粒,被害粒および着色粒歩合が低くなり,精米蛋白質含有率が低く玄米白度と精米白度が高かった。一方,地域間でこれらの関係が概して不明確だったが,これは生育期別気温,生育特性および整粒,未熟粒歩合における変動（最小値最大値の差異および変動係数）が地域間よりも年次間で大きいためだった。ただし,被害粒と着色粒歩合は,変動が地域間よりも年次間で小さく,年次と地域込みで登熟気温が各845,857℃で最低となる2次回帰の関係を示した。また,整粒歩合では年次間と地域間で,被害粒と着色粒歩合では年次間のみで,それらが不良なほど年次では地域間,地域では年次間の変動係数が大きかった。なお,乾燥後も半透明な未ハゼ粒は,白濁不透明なハゼ粒との間に蛋白質含有率,澱粉含有率,澱粉粒の大きさ,精製澱粉でのヨウ素吸収曲線の最大吸収波長とその吸光度の理化学的特性および餅生地明度で差がほぼ無く,...     

Optimization of the Multishift QR Algorithm with Coprocessors for Non-Hermitian Eigenvalue Problems

The multishift QR algorithm is efficient for computing all the eigenvalues of a dense, large-scale, non-Hermitian matrix. The major part of this algorithm can be performed by matrix-matrix multiplications and is therefore suitable for modern processors with hierarchical memory. A variant of this algorithm was recently proposed which can execute more computational parts by matrix-matrix multiplications. The algorithm is especially appropriate for recent coprocessors which contain many processor-elements such as the CSX600. However, the performance of the algorithm highly depends on the setting of parameters such as the numbers of shifts and divisions in the algorithm. Optimal settings are different depending on the matrix size and computational environments. In this paper, we construct a performance model to predict a setting of parameters which minimizes the execution time of the algorithm. Experimental results with the CSX600 coprocessor show that our model can be used to find the optimal setting.     

Verification test results of a cutting technique for the ITER blanket cooling pipes

For replacement of the first wall (FW) of the international thermonuclear experimental reactor (ITER), cutting and welding tools for the cooling pipes must be able to access a pipe from the surface side of the FW and cut/weld the pipe from the inside the cooling pipe (inner diameter: 42.72 mm, thickness: 2.77 mm). The cutting tool for the pipe end is required to cut a flat plate circularly from the surface side of the FW (cutting diameter: approximately 44 mm, plate thickness: 5 mm). To determine the specifications for both the tools and the blanket hydraulic connections, the ITER Organization (IO) and the Japan Domestic Agency (JADA) conducted research and development activities regarding the FW replacement. This paper describes the current status of the development of cutting tools for the cooling pipe connection.     

Preparation of carbon alloy catalysts for polymer electrolyte fuel cells from nitrogen-containing rigid-rod polymers

‘Carbon Alloy Catalysts’ (CAC), non-precious metal catalysts for the oxygen reduction reaction (ORR), were prepared from various kinds of nitrogen-containing rigid-rod aromatic polymers, polyimides, polyamides and azoles, by carbonization at 900 °C under nitrogen flow. The catalytic activity for ORR was evaluated by the onset potential, which was taken at a current density of −2 μA cm⁻². Carbonized polymers having high nitrogen content showed higher onset potential. In particular, CACs derived from azole (Az5) had an onset potential of 0.8 V, despite being was prepared without any metals.     

Stable organoboron polymers prepared by hydroboration polymerization of dienes with tripylborane

Summary Hydroboration polymerization between diene monomers and 2,4,6-triisopropylphenylborane (tripylborane) gave organoboron main-chain polymers. The polymerization was carried out by adding a diene monomer to a THF solution of tripylborane at room temperature under nitrogen. The obtained polymers were found to be more stable compared with the polymers prepared from thexylborane or mesitylborane. Received: 27 November 2000/Accepted: 11 December 2000     

Promoting effect of calcium on reduction of NO by C3H6 over V2O5/ZrO2 catalysts

The reduction of nitrogen monoxide by propene on V₂O₅/ZrO₂ doped with or without calcium has been studied by FTIR spectroscopy as well as by analysis of the reaction products. Considerable promoting effect of calcium doping on the reduction of nitrogen monoxide by propene was observed on the V₂O₅/ZrO₂ catalysts. For the reaction of a mixture of NO+C₃H₆, carbonyl and carboxylate species were observed above 373 K, although nitrate species formed at room temperature on V₂O₅/ZrO₂ doped with calcium. No bands due to a compound including both carbon and nitrogen atoms were observed. Thus, the redox mechanism, i.e. propene reduces the catalyst and nitrogen monoxide oxidizes the catalyst, is confirmed on V₂O₅/ZrO₂ catalysts doped with or without calcium. The analysis of the V=O band in the region of 1100–900 cm⁻¹ indicates that this promotion is mainly due to new V=O species formed by the addition of calcium onto the catalyst. This species is easily reproduced in comparison with the other V=O species on the surface in the reoxidation process of the catalyst.     

Ionization current in N2 gas: XI. three‐dimensional analysis for loss processes of metastable particles affected by the reflection at the boundary

Loss of the metastable nitrogen molecule N₂(A³Σ⁺_u) in plane parallel electrodes has been investigated by us previously by solving the diffusion equation. Our procedure is based on an analysis using the third kind of boundary condition, which can take account of finite values for the density of N₂(A³Σ⁺_u) at the electrode surfaces. The values of the effective lifetime of N₂(A³Σ⁺_u) calculated from this analysis were reasonably consistent with our experiments. This paper describes the behavior of the effective lifetimes of RN₂(A³Σ⁺_u) in a cylindrical cavity. The analytical treatment of the diffusion equation for N₂(A³Σ⁺_u) proposed by us is extended to three‐dimensional space. We systematically report the effective lifetimes of metastable molecules in a cylindrical cavity. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 1–8, 2000