Yasushi Idemoto

Microbial conversion of n-alkanes into glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma (Candida antarctica)

Abstractn-Alkanes ranging from C12 to C18 were converted into glycolipid biosurfactants, mannosylerythritol lipids (MEL), by resting cells of Pseudozyma (Candida) antarctica T-34. The highest yield (0.87 g g−1 substrate) was obtained from 6% (v/v) of n-octadecane after 7 days reaction. The amount of MEL reached 140 g l−1 by intermittent feeding of the substrate.

Improvement of ethanol selectivity of silicalite membrane in pervaporation by silicone rubber coating

In order to improve the pervaporation performance of silicalite membrane, two types of silicone rubber, KE45 and KE108, were coated on the membrane surface. The initial molecular weight of KE108 is high and vulcanizing starts when it comes into contact with moisture in air, whereas the initial molecular weight of KE45 is low and vulcanizing starts when it is mixed with a catalyst. KE108 was found to be more effective than KE45 in enhancing the ethanol selectivity of silicalite membranes. A membrane coated using a 3 wt.% KE108 hexane solution showed separation factor of α=125 with a total flux of 0.14 kg/m2 h.

Oxygen Nonstoichiometry and valences of bismuth and copper in Bi2.00Sr1.88Ca1.00Cu2.14Oy

Abstract The oxygen nonstoichiometry of Bi 2.00 Sr 1.88 Ca 1.00 Cu 2.14 O y was determined as a function of temperature and oxygen partial pressure. It was found that the shape of y −log P 0 2 curves above 800°C is quite different from that below 800°C. Above 800°C, the y −log P 0 2 relation resembled those of other kinds of high T c superconducting oxides such as Ba 2 YCu 3 O 7−δ and (La 1− x Sr x ) 2 CuO 4−δ . However, below 800°C y slightly depended on the temperature but did not depend on the oxygen partial pressure. It was found by chemical analysis on quenched samples that the copper valence was 2.07 irrespective of the annealing condition, and the bismuth valence was nearly constant when the annealing temprature was above 800°C but increased with the decrease of the annealing temperature below 800°C. The tailing of resistivity-temperature curves in the vacinity of the critical temperature seemed to be due to the existence of Bi 5+ and neutral oxygen species.

T-log PO2 diagram and copper valence of Nd1.85Ce0.15CuO4−δ

Abstract The stability domain of single phase Nd 1.85 Ce 0.15 CuO 4−δ and the copper valence contour line are given in a T -log P O 2 diagram. The cerium valence is about 3.84 irrespective of the annealing conditions. Superconductivity appears when the copper valence is below 1.84.

Oxygen nonstoichiometry of 2223 phase Bi-Pb-Sr-Ca-Cu-O system superconducting oxide

Abstract The oxygen nonstoichiometry of Bi 1.74 Pb 0.27 Sr 1.86 Ca 2.09 Cu 3.04 O y (2223 phase) was determined as a function of temperature and oxygen partial pressure under the condition that Ca 2 PbO 4 was not formed. It was also found that PbO evaporated from the 2223 phase about 700° C in a low oxygen pressure range. Below about 700° C, the dependences of oxygen content on both temperature and oxygen partial pressure were weak, whereas they were strong above 700° C. The effect of PbO content on properties of the 2223 phase was studied by allowing PbO to evaporate under 500° C and oxygen 800° C in oxygen of 0.01 atm for different annealing periods. It was found that the critical temperature and the valences of copper and bismuth remained constant in spite of a loss of PbO.

Preparation of polyacrylonitrile ultrafiltration membranes for wastewater treatment

Abstract The preparation conditions of a polyacrylonitrile (PAN) ultrafiltration membrane for wastewater treatment was investigated. The PAN membranes were prepared by the phase-inversion process in a water gelation bath using casting solutions of varying compositions of PAN/polyvinylpyrolidone (PVP)/N,N-dimethylacetamide (DMAc) and showed a molecular weight cut-off of 50,000–500,000. Especially, the membrane prepared from casting solutions with PVP and annealed at 80°C in water showed high water flux with a molecular weight cut-off of 500,000. Furthermore, the composite membranes of PAN-acrylic acid, prepared by the photo-induced graft polymerization technique, improved high performance.

Oxygen nonstoichiometry of A Y(Ba1−xSrx)2Cu3O7−δ superconductor

Abstract The oxygen deficit δ of Y(Ba 1− x Sr x ) 2 Cu 3 O 7−δ was measured as a function of log P O 2 and temperature for x =0, 0.1, 0.3 and 0.5. It was found that a constant temperature shift of the δ-log P O 2 curve to the lower δ side increases as x increases. Partial molal quantities Δ S O 2 , Δ H O 2 were calculated from the plots of RT ln P O 2 vs. T and R ln P O 2 vs. 1/ T , respectively. It was found that all the Δ S O 2 −δ plots fall on a single line, irrespective of x , but the -Δ H O 2 value increases as x increases, especially in a composition range where δ is higher than 0.5. Lattice parameters for different x were measured as a function of δ. Shift of the ortho-tetra phase boundary to the lower δ side increased as x increased. The critical temperature was measured as a function of δ for different x . The plateau on the T c −δ curve observed for YBCO disappeared by the substitution of strontium for barium.

The electrodeposition of amorphous Co-Zn alloy from ambient temperature molten salt electrolytes

Abstract The Co-Zn alloy deposit was obtained from an ambient temperature molten salt electrolyte, CoCl2-ZnCl2-1-butylpyridinium chloride system, and from an organic solvent added bath. The Co content in the deposited Co-Zn alloy was continuously controlled from 0 to 100 wt% by controlling the bath composition and the current density. The morphology and the current efficiency of the Co-Zn alloy deposit were significantly improved by an addition of organic solvent, i.e., propylene carbonate or ethyl alcohol, to the bath. Moreover, the bath temperature could be decreased from 130 to 25 °C by the addition of organic solvent. It was determined that the crystal structure of the Co-Zn alloy deposit changes from the binary phase of Zn and an intermetallic compound, Co5Zn21, to that of Co and the intermetallic compound as a function of the Co content in the deposit. Moreover, it was found that an amorphous deposit of Co-Zn alloy can be obtained from this molten electrolyte.

Standard enthalpies of formation of member oxides in the Bi-Sr-Ca-Cu-O system

Abstract The standard enthalpies of formation of member oxides in the Bi-Sr-Ca-Cu-O system have been determined by the solution calorimetric method. On the basis of enthalpy, the chemical stability of member oxides was discussed. It was found that the chemical stability increases in the order of 2223

Effect of High-Pressure Oxygen Annealing on Bi2SiO5-Added Ferroelectric Thin Films

The crystallization temperature of typical ferroelectric films such as PbZr1-XTiXO3 (PZT), SrBi2Ta2O9 (SBT), and (Bi,La)4Ti3O12 (BLT) was found to decrease by 150 to 200°C in a chemical solution deposition method by adding Bi2SiO5 (BSO) in the sol-gel solutions. It was also found that the ferroelectric and insulating characteristics of the BSO-added films were significantly improved by annealing in high-pressure oxygen up to 9.9 atms. Three-orders-of-magnitude improvement of the leakage current density was observed in BSO-added BLT films after annealing at 9.9 atms, while pronounced increase of the saturation polarization level was observed in BSO-added SBT and PZT films. From cross-sectional transmission electron microscopy (TEM) observations, the origin of the improved characteristics was speculated to be the structural change of the films.