Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Catalytic oxidation of biphenyl derivatives was investigated using laccase in a homogeneous aqueous-organic system. A thermostable laccase from Trametes sp. showed the highest catalytic activity for the oxidation of 4-hydroxybiphenyl (4-HB) at a reaction temperature of 60 degrees C when dimethylsulfoxide (DMSO) was employed as a co-solvent. Furthermore, the catalytic performance was successfully enhanced by the incorporation of a laccase mediator system (LMS) into the aqueous-DMSO media. The catalytic performance strongly depended on the type of mediator, and the highest activity was observed with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as mediator, suggesting the importance of the selection of a suitable mediator. It was verified that this mediator system is applicable to the oxidation of several biphenyl derivatives with hydroxyl groups.     

Application of the double slip plane crack model to temperature and strain rate sensitive BCC metals

The double slip plane crack model proposed by Weertman, Lin and Thomson (1982) has been applied to model the effect of temperature and strain rate on the stress intensity factor at a crack tip in temperature and strain rate sensitive materials. Increase in temperature or decrease in strain rate (as well as a decrease in slip plane spacing) are shown to increase the shielding of the crack tip by dislocation distributions on the slip planes. Furthermore, the effect of temperature on the fracture toughness, K_llc, at various strain rates was shown to exhibit the same sigmoidal shaped curve seen for K_lc data in typical alloy steels.     

Discrimination of psychoactive fungi (commonly called "magic mushrooms") based on the DNA sequence of the internal transcribed spacer region

'Magic mushrooms' (MMs) are psychoactive fungi containing the hallucinogenic compounds, psilocin (1) and psilocybin (2). Since June 6, 2002, these fungi have been regulated by the Narcotics and Psychotropics Control Law in Japan. Because there are many kinds of MMs and they are sold even as dry powders in local markets, it is very difficult to identify the original species of the MMs by morphological observation. Therefore, we investigated the internal transcribed spacer (ITS) region in the ribosomal RNA gene of MMs obtained in Japanese markets to classify them by a genetic approach. Based on the size and nucleotide sequence of the ITS region amplified by PCR, tested MMs were classified into 6 groups. Furthermore, a comparison of the DNA sequences of the MMs with those of authentic samples or with those found in the databases (GenBank, EMBL and DDBJ) made it possible to identify the species of tested MMs. Analysis by LC revealed that psilocin (1) was contained at the highest level in Panaeolus cyanescens among the MMs, but was absent in the Amanita species.     

Advanced CD Control Technology for 65-nm Node Dual Damascene Process

This paper describes an advanced critical dimension (CD) control technology for a 65-nm node dual damascene process and beyond. A newly developed deposition enhanced shrink etching (DESE) process was introduced into both via and trench etching. This technology realizes not only dynamic via shrink ranging 40 nm but also accurate trench CD control by feedforward technology. Etching performance was investigated by electrical results of 65-nm Cu/low-k interconnects using porous chemical-vapor deposition SiOC. The 100% yields of 60-M via chains verified the DESE process robustness.     

Application of stereoscopic satellite images for studying Quaternary tectonics in arid regions

We introduce a flexible method for creating stereoscopic pairs of images from any interesting sub-area of the same scene of Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper (ETM) and Indian Remote Sensing (IRS)-1C Pan remote sensing data by setting the Z scale. As a test of this method, stereoscopic images were used to study Quaternary deformation along the Tian Shan Orogenic Belt, north-west China. The new stereoscopic images can then provide detailed information of Quaternary deformation structures, including spatial distribution and arrangement pattern of fold structures, fault scarps and displacement of alluvial fans, terraces and drainage systems along active faults, in three dimensions. The strike–slip partitioning has been revealed by interpretation of stereoscopic images within Chinese Tian Shan. Structural interpretations derived from stereoscopic analysis were confirmed to a high degree of accuracy during a subsequent field study. The satellite remote sensing stereoscopic technique is an effective method of analysing Quaternary tectonic deformation in remote arid to semi-arid regions such as the Tian Shan.     

Construction of a plasmid carrying both CTP synthetase and a fused gene formed from cholinephosphate cytidylyltransferase and choline kinase genes and its application to industrial CDP-choline production: enzymatic production of CDP-choline from orotic acid (Part II)

A new method for enzymatic production of cytidine diphosphate choline (CDP-choline) from orotic acid and choline chloride was developed. To establish an industrial manufacturing process, we constructed a plasmid, pCKG55, which simultaneously expressed in Escherichia coli the three following enzymes; CTP synthetase (encoded by the pyrG gene from E. coli), cholinephosphate cytidylyltransferase (encoded by the CCT gene from Saccharomyces cerevisiae), and choline kinase (encoded by the CKI gene from S. cerevisiae). CCT and CKI genes on pCKG55 were designed to be expressed as a single CCT/CKI fused protein. This CCT/CKI fused protein retained both activities and the thermal stability of its cholinephosphate cytidylyltransferase activity was nearly the same as the native CCT enzyme. Corynebacterium ammoniagenes KY13505 and E. coli MM294/pCKG55 were cultured in 5-liter jar fermentor independently. Equal volumes of each broth were mixed in a 2-liter jar fermentor, and then the enzymatic reaction was done using 47 mM orotic acid and 60 mM choline chloride as substrates. After 23 h of the reaction at 32 degrees C, 21.5 mM (11 g/liter) of CDP-choline was accumulated.     

The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K

The pesting behavior of MoSi₂ and Mo(Si,Al)₂ has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO₃ vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO₃ grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)₂ occurs in the same way, however, its rate is much lower than that of MoSi₂. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.     

Precision dilatometer analysis of neutron-irradiated nuclear graphite recovery process up to 1673 K

Specimens of two kinds of isotropic nuclear graphite, IG-110U and ETP-10, were neutron-irradiated at fluence of 1.92 × 10²⁴ n/m² (E > 1.0 MeV) at 473 K. The recoveries of the macroscopic lengths of these specimens during isothermal and isochronal annealing at temperatures of up to 1673 K were investigated in a step-wise manner by using a precision dilatometer. The macroscopic lengths after isochronal annealing for 6 h at each temperature decreased gradually as the temperature was increased to 1673 K. The recovery trends of the c-axis and a-axis lattice parameters differed from one another, and from the macroscopic length recovery trends. For the IG-110U specimen, the activation energies (E_a) of macroscopic volume recovery corresponding to annealing at 523–773, 773–923, 923–1073, and 1073–1173 K were found to be 0.15, 0.34, 0.73, and 2.59 eV, respectively. For the ETP-10 specimen, the E_a corresponding to 523–923, 923–1223, and 1223–1373 K were determined to be 0.15, 0.46, and 2.19 eV, respectively. These results indicate that both graphite specimens underwent three or four stages of macroscopic length recovery between 523 K and the annealing temperatures at which their initial lengths were recovered. It is suggested that during the first stage recovery proceeded via the migration of single interstitials along the basal plane and the resulting V-I recombination. In the middle stages, recovery occurred due to the migration of interstitial groups such as C₂ along the basal plane, while in the last stage, it proceeded via through-layer migration of interstitials or migration of single vacancies.     

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of ¹⁰B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of ¹⁰B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of ¹⁰B in B₄C or H₃BO₃. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of ¹⁰B required in the field of nuclear applications.     

Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.