Biosynthesis of p-anisaldehyde by the white-rot basidiomycete Pleurotus ostreatus

The white-rot basidiomycete Pleurotus ostreatus produced sweet flavor compounds on a liquid medium. The major and minor compounds identified by GC-MS analysis were p-anisaldehyde (4-methoxybenzaldehyde) and 3-chloro-p-anisaldehyde (3-chloro-4-methoxybenzaldehyde), respectively. p-Anisaldehyde was only produced under static culture conditions. Differences in the type and quantity of flavor compounds produced among wild strains of P. ostreatus were observed. Aryl alcohol oxidase and manganese peroxidase activities increased parallel to the production of p-anisaldehyde. These results indicated that the biosynthesis of p-anisaldehyde is concerned in generating H2O2-activated peroxidase in the lignin-degradation system. Addition of L-tyrosine to the culture led to higher production of p-anisaldehyde. The flavor extract, which contains p-anisaldehyde, exhibited antimicrobial activity against Bacillus subtilis, Pseudomonas aeruginosa, Aspergillus niger and Fusarium oxysporum.     

Ammonia assimilation in Klebsiella pneumoniae F-5-2 that can utilize ammonium and nitrate ions simultaneously: purification and characterization of glutamate dehydrogenase and glutamine synthetase

The two ammonia-assimilating enzymes glutamate dehydrogenase (GDH; EC 1.4.1.4) and glutamine synthetase (GS; EC 6.3.1.2) were synthesized steadily during the cell growth of Klebsiella pneumoniae F-5-2 that can utilize NH4+ and NO3- simultaneously under aerobic conditions. The enzymes were purified to homogeneity from cell extracts and characterized. The molecular mass of the purified GDH was 300 kDa with six identical 52-kDa subunits. GDH showed its maximal activity (aminating) at pH 8.0 and was stable between pHs 5.5 and 11.5. The enzyme was NADP-specific and strongly inhibited by Ag+. It catalyzed the amination of 2-ketovalerate, 2-ketoadipate, and 2-ketobutyrate, in addition to 2-ketoglutarate. The purified GS has a molecular mass of 470 kDa with eight identical 60-kDa subunits. GS showed its maximal activity at pH 8.0 and was stable between pHs 6.0 and 7.0. The enzyme was strongly inhibited by Fe3+, Hg2+, and Cu2+.     

Robust topology optimization of optical cloaks under uncertainties in wave number and angle of incident wave

This article presents a robust topology optimization method for optical cloaks under uncertainties in the wave number and angle in the incident wave. We first discuss the governing equation derived from Maxwell's equation, and extend it to the entire domain including the dielectric material and air, based on the level set-based topology optimization method. Next, a robust optimization problem is formulated as a minimization problem of the weighted sum of the scattered wave norm and its standard deviation with respect to the wave number and angle of the incident wave. The standard deviation is mathematically expressed by the Taylor series approximation and the use of the adjoint variable method. The design sensitivity of the objective functional is also derived by the adjoint variable method. An optimization algorithm is then constructed, based on the proposed formulation for robust designs of optical cloaks. Several numerical examples are finally provided to demonstrate the validity and utility of the proposed method.     

Smear growth on head slider surface from siloxane outgas on heat assisted magnetic recording

Microsystem Technologies - In this study, the smear by the lubricant and siloxane pickup at the laser heating in the heat assisted magnetic recording (HAMR) was evaluated using our developed...     

Preparations and reactions of alkyl ethers of some aldohexoses

Aldohexose, such asd-glucose,d-galactose ord-mannose, reacted with acetone to give the following O-isopropylidene derivatives: 1,2;5,6-di-O-isopropylidene-d-glucofuranose (IA), 1,2;3,4-di-O-isopropylidene-d-galactopyranose (IB) or 2,3;5,6-di-O-isopropylidene-D-mannofuranose (IC). The O-isopropylidene derivative (IA～IC) reacted with alkyl/alkenyl halogenide to yield aldohexose ether compounds containing di-O-isopropylidene group, 3-O-alkyl-1,2;5,6-di-O-isopropylidene-d-glucofuranose (II), 6-O-alkyl-1,2;3,4-di-O-isopropylidene-d-galactopyranose (III) or 1-O-alkyl-2,3;5,6-di-O-isopropylidene-d-mannofuranoside (IV), in good yields. The Williamson ether synthesis was carried out using phase-transfer catalysis (PTC). The derived aldohexose alkyl ether containing di-O-isopropylidene group was hydrolyzed to give 3-O-alkyl-1,2-O-isopropylidene-d-glucofuranose (V) as a partial hydrolysis product; the complete hydrolysis of I～IV gave, as expected, 3-O-alkyl-glucopyranose (VI), 6-O-alkyl-galactopyranose (VII) or 1-O-alkyl-mannofuranoside (VIII). Further alkylation of (V) with Mel under PTC and subsequent acid hydrolysis gave 3-O-alkyl-5,6-di-O-methyl-d-glucofuranose (X). Methanolysis of III with catalytic amounts of H₂SO₄ gave 1-O-methyl-6-O-alkyl-d-galactofuranoside (XI). The elucidation of the galactofuranoside skeleton of (XI) was determined by means of its¹³C nuclear magnetic resonance spectra. The O-alkyl aldohexoses, e.g., X and XI, were evaluated and found to be emulsifiers.     

Preliminary results of simultaneous radon and thoron tests in Ottawa

Ottawa is the capital city of Canada. In the previous crossCanada radon survey, Ottawa was not included. There is greatinterest to know radon level as well as thoron concentrationin Ottawa homes. Therefore, radon/thoron discrimination detectorsdeveloped at the National Institute of Radiological Sciencesin Japan were deployed in 93 houses for a period of 3 months.As expected, thoron is present in Ottawa homes. Radon concentrationsranged from 8 to 1525 Bq m^–3 while thoron concentrationsvaried from 5 to 924 Bq m^–3. The arithmetic mean of radonand thoron concentrations were found to be 110 ± 168and 56 ± 123 Bq m^–3, respectively.     

Measurement of the 77Se(γ, n) cross section and uncertainty evaluation of the 79Se(n, γ) cross section

The ⁷⁷Se (γ, n) cross section was measured for the energy range from 7.6 to 13.8 MeV by using quasi-monochromatic laser-Compton scattering γ-rays. The advanced method to deduce γ-ray strength functions from (γ, n) cross section was developed. By utilizing the method, the γ-ray strength functions of ^{77, 78, 80}Se were deduced so as to reproduce the ^{77, 78, 80}Se (γ, n) cross sections measured in this work and previous systematic measurements. The inverse (n, γ) cross sections for ^{76, 77, 79}Se isotopes were calculated using the statistical model calculation code CCONE with the deduced γ-ray strength functions. The uncertainty of the calculated ⁷⁹Se(n, γ)⁸⁰Se cross section was evaluated by comparing the calculations and the experimental data on ^{76, 77}Se (n, γ) cross sections.     

Development of advanced arresters for GIS from 66 kV to 500 kV

New zinc oxide elements with a varistor voltage about twice that of conventional ones have been developed by reducing the ZnO grain size with a new additive, making it possible to halve the series number of elements in metal oxide surge arresters. The advanced arresters with these elements for GIS are smaller in volume by 40 to 60% compared with conventional ones. These advanced MOAs increase the flexibility in positioning MOAs and optimizing the GIS layout. This paper describes the performance of the new elements, the specification and construction of the advanced MOAs, and the results of typical evaluation tests. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 34–42, 2000