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71.
A. Sakaguchi K. Kawai T. Imanaka S. Endo M. Yamamoto 《The Science of the total environment》2010,408(22):5392-5398
The first results on the feasibility of using 236U to reconstruct the level and spatial distribution of close-in fallout deposition from the Hiroshima A-bomb are reported, coupled with the use of global fallout 137Cs and 239 + 240Pu. The results for global fallout 236U in soil samples (0-30 cm) from Ishikawa prefecture showed that the deposition density of 236U from the global fallout can be accurately evaluated using AMS. All deposited 236U, 137Cs and 239 + 240Pu appeared to have been recovered using 30-cm cores. It was also noted from the depth profiles for 236U/239 + 240Pu and 236U/137Cs ratios that the downward behavior of 236U in the soil was apparently similar to that of 239 + 240Pu, while the 137Cs was liable to be retained in upper layers compared with 236U and 239 + 240Pu. The accumulated levels were 1.78 × 1013 atoms m− 2 for 236U, 4340 Bq m− 2 for 137Cs and 141 Bq m− 2 for 239 + 240Pu. The ratios of 236U/137Cs and 236U/239 + 240Pu were (4.10 ± 0.12) × 109 and (1.26 ± 0.04) × 1011 atoms Bq− 1, respectively. Results of 236U, 137Cs and 239 + 240Pu measurements for the seven soil cores (0-30 cm) from Hiroshima were discussed on the basis of ratios of 236U/137Cs and 236U/239 + 240Pu by comparing with those from the background area in Ishikawa, indicating that the global fallout dominates the current level of 236U accumulation in soil in the Black-rain area around Hiroshima after the Hiroshima bomb, and the contribution of the close-in fallout 236U produced by the Hiroshima A-bomb seems difficult to observe. 相似文献
72.
An agarolytic bacterium was isolated from soil in Gifu prefecture, Japan, and identified as Bacillus sp. strain MK03. The strain secreted neoagarooligosaccharide hydroluse into the culture medium. The enzyme was purified 49.7-fold from the culture fluid by ammonium sulfate precipitation and anion-exchange and gel-filtration column chromatographic methods. The purified enzyme appeared as a single band on polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE. Estimations of the molecular mass by gel filtration and SDS-PAGE gave values of 320 kDa and 42 kDa, respectively, indicating that the enzyme is octametric. The enzyme cleaved the alpha-1,3 linkage in neoagarobiose to produce 3,6-anhydro-L-galactose and D-galactose. It also selectively cleaved the alpha-1,3 linkage at the nonreducing end in neoagarotetraose or neoagarohexaose to give 3,6-anhydro-L-galactose and agarotriose or agaropentaose. The optimum temperature and pH for the enzyme were 30 degrees C and 6.1, respectively. The N-terminal amino acid sequence showed no homology to sequences of other known neoagarooligosaccharide hydrolases and agarases. 相似文献
73.
Kim J Yamasaki R Park J Jung H Lee H Kawai T 《Journal of Bioscience and Bioengineering》2004,97(2):138-140
Protein adsorption on a gold surface is investigated by comparing the results of quartz crystal microbalance method and atomic force microscopy. The adsorption of streptavidin on functional gold surfaces is directly monitored by a quartz crystal microbalance, and confirmed by atomic force microscopy. For this investigation, a modified gold substrate is fabricated to obtain a topographic image of streptavidin molecules. Both methods show a correlation in terms of the highly dense protein single-layer formation, and the modified gold electrode shows a slightly denser protein layer formation because of the difference in substrate geometry as compared with that of a mica surface. 相似文献
74.
Kawai E Akatsuka H Sakurai N Idei A Matsumae H Shibatani T Komatsubara S Omori K 《Journal of Bioscience and Bioengineering》2001,91(4):409-415
We have isolated a lipase-overproducing mutant, GE14, from Serratia marcescens 8000 after three rounds of N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The mutant GE14 produced 95 kU/ml of extracellular lipase in the lipase medium, which was about threefold higher than that of produced by the original strain 8000. Enzymatic characteristics including specific activity of purified lipases from culture supernatants of GE14 and 8000 were almost same. The lipase gene (lipA) of GE14 contained two base substitutions; one in the promoter region and another in the N-terminal region of the lipA gene without an amino acid substitution. Promoter analysis using lipA-lacZ fusion plasmids revealed that these substitutions were responsible for the increase in the lipA expression level, independently. In contrast, no base substitution was found in the genes encoding the lipase secretion device, the Lip system. In addition, the genes coding for metalloprotease and the cell surface layer protein which are both secreted through the Lip system and associated with extracellular lipase production, also contained no base substitution. The strain GE14 carrying a high-copy-number lipA plasmid produced a larger amount of the extracellular lipase than the recombinant strains of 8000 and other mutants also did, indicating that GE14 was not only a lipase-overproducing strain, but also an advantageous host strain for overproducing the lipase by a recombinant DNA technique. These results suggest that the lipase-overproducing mutant GE14 and its recombinant strains are promising candidates for the industrial production of the S. marcescens lipase. 相似文献
75.
Determination of alkylphenols,bisphenol A,benzophenone and phthalates in containers of baby food,and migration into food simulants 总被引:2,自引:0,他引:2
Ozaki A Yamaguchi Y Okamoto A Kawai N 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(4):260-266
Infants, whose growth and development are highly dependent upon the endocrine system, are particularly vulnerable to endocrine disruptor exposure. In our study, we examined whether or not alkylphenols, bisphenol A, benzophenone, di(2-ethylhexyl)adipate and 10 phthalates are present in containers of baby food. Furthermore, the migration into food-simulating solvents was also examined. Sixteen types of containers of baby food, obtained on the Japanese market in 2001, were examined: 8 glass bottle types, 1 plastic type, 1 metallic package (laminated with plastic) and 6 multilayered laminated film packages. Alkylphenols, benzophenone, bisphenol A and di(2-ethylhexyl)adipate were not detected in any of the samples. On the other hand, dibutylphthalate (DBP) was detected in 7 samples (1.2-9.1 micrograms/sample), and di(2-ethylhexyl)phthalate (DEHP) was detected in 15 samples (1.3-18 micrograms/sample). Migration tests were carried out for 5 samples, and the levels of DBP and DEHP that migrated into n-heptane were 0.68-1.7 micrograms/sample and 0.33-3.5 micrograms/sample, respectively. From these results, a baby's intake levels of DBP and DEHP were estimated to be about 1/2,500 and 1/90-300 of the tolerable daily intake (TDI), respectively. 相似文献
76.
Kunio Matsui Jun Kikuma Masamichi Tsunashima Tetsuji Ishikawa Shin-ya Matsuno Akihiro Ogawa Masugu Sato 《Cement and Concrete Research》2011,(5):510-519
The hydrothermal formation of tobermorite during the processing of autoclaved aerated concrete was investigated by in situ X-ray diffraction (XRD) analysis. High-energy X-rays from a synchrotron radiation source in combination with a newly developed autoclave cell and a photon-counting pixel array detector were used.To investigate the effects of the silica source, reactive quartz from chert and less-reactive quartz from quartz sand were used as starting materials. The effect of Al addition on tobermorite formation was also studied. In all cases, C-S-H, hydroxylellestadite and katoite were clearly observed as intermediates.Acceleration of tobermorite formation by Al addition was clearly observed. However, Al addition did not affect the dissolution rate of quartz. Two pathways, via C-S-H and katoite, were also observed in the Al-containing system. These results suggest that the structure of initially formed C-S-H is important for the subsequent tobermorite formation reactions. 相似文献
77.
Kawai K. Koike K. Takei Y. Onozawa A. Obara H. Ichino H. 《Solid-State Circuits, IEEE Journal of》1999,34(1):12-17
A regenerator-section terminating digital large-scale-integration chip for an STM-16 (2.5-Gbit/s synchronous optical network/synchronous digital hierarchy) regenerator has been developed using low-power bipolar technologies. The high-speed performance of bipolar devices enabled four or more chips, including a demultiplexer and a multiplexer, to be integrated into a single chip. The low-power dissipation of 557 mW, only about one-tenth that of previously reported chips, was achieved through the use of four design steps: one-chip integration architecture, power management, 2.5-V emitter-coupled logic, and power optimization 相似文献
78.
79.
Takeshi Watanabe Tomoko K. Shimizu Yoshitaka Tateyama Yousoo Kim Maki Kawai Yasuaki Einaga 《Diamond and Related Materials》2010,19(7-9):772-777
The physical and electrochemical properties of boron-doped polycrystalline diamond electrodes, prepared with various B/C ratio, i.e., 0.1%, 0.5% (BDD-A), 1% (BDD-B), and 5% (BDD-C), were investigated. Electrochemical measurements of the heavily boron-doped films (BDD-C) showed giant electric double-layer capacitance and activity which is significantly larger than BDD-A and BDD-B as well as glassy carbon electrodes. However, interestingly, actual boron concentration of BDD-C was observed to be almost the same as that of BDD-B by secondary ion mass spectroscopy (SIMS) and glow discharge optical emission spectroscopy (GDOES) analysis. It is suggested that the large capacitance is due to a few sp2-bonded carbon impurities, which was observed only in BDD-C, although the amount of the sp2-bonded nondiamond species are very small. In the present work, the reason for the interesting electrochemical properties of heavily boron-doped diamond electrodes is discussed. Furthermore, dimensional stability of the electrodes was also confirmed by conducting harsh anodic treatment. 相似文献
80.
A. Sakaguchi K. Kawai F. Quinto J. Tomita N. Whitehead 《The Science of the total environment》2009,407(14):4238-4242
The global fallout 236U level in soil was deduced from measurements of 236U, 239+240Pu and 137Cs in surface soils which are solely influenced by global fallout. A total of 12 soil cores from the depths of 0-10, 0-20 and 0-30 cm were collected at a flat forest area in Japan. Concentrations of 239+240Pu and 238U were determined by α-particle spectrometry, while the 236U/238U ratio was measured with accelerator mass spectrometry (AMS). Consistent 236U/239Pu ratios between 0.212 and 0.253 were found. Using this ratio, the total global fallout of 236U on the earth is estimated to be as much as ca. 900 kg. This knowledge will contribute to the promotion of research on U isotopes, including 236U, for the fields of geo-resources, waste management and geochemistry. 相似文献