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131.
132.
S. Tonouchi H. Habuki Z. Igari T. Hashimoto Y. Takizawa 《Journal of Radioanalytical and Nuclear Chemistry》2000,243(2):433-445
Natural and artificial radionuclide concentrations in sea sediments around Kashiwazaki-Kariwa nuclear power station have been investigated with respect to the particle size distributions and the ignition losses during assay. Plutonium concentrations around the south and north discharge area, ranged from 0.054 to 0.24 Bq·kg-1 (average 0.145) and 0.15 to 0.25 Bq·kg-1 (average 0.213), respectively. Plutonium concentrations were significantly related to erosion and accumulation processes of sediments in both south and north discharges. Additionally, the ratios of 239Pu to 240Pu were evaluated with ICP-MS to determine the origin of the Pu-isotopes. Uranium-238, 232Th and 40K were found in concentration range of 7.3–67, 12–100 and 260–560 Bq·kg-1 with mean concentrations of 20, 29 and 390 Bq·kg-1, respectively. It is assumed that the relatively high concentrations of the natural radionuclides such as U and Th are due to the presence of minerals (the south discharge regions). On the basis of these results, the origin of the Pu-isotopes was assumed to be derived from fallout of the past atmospheric nuclear tests. 相似文献
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135.
Dr. Hidetoshi Noda Yasuko Asada Dr. Tatsuro Maruyama Dr. Naoki Takizawa Dr. Nobuo N. Noda Prof. Dr. Masakatsu Shibasaki Dr. Naoya Kumagai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4299-4304
A new scaffold for producing efficient organic fluorescent materials was identified: 2,5-diamino-4,6-diarylpyrimidine featuring a C4N4 elemental composition. Single-step installation of two aryl groups at the 4,6-positions of the pyrimidine core delivered fluorescent organic materials in a modular fashion. A range of fluorescent compounds with distinct absorption/emission properties was readily accessed by changing the aromatic attachments. A generally high absorption coefficient and quantum yield were observed, including C4N4 derivatives that could fluoresce even in the solid state. The two amino groups at the 2,5-positions of the pyrimidine were essential for intense fluorescence with a large Stokes shift, which was corroborated by structural relaxation to a p-iminoquinone-like structure in the excited state. Besides live-cell imaging capabilities, fluorescent labeling of a protein involved in autophagy elucidated a new protein–protein interaction, supporting potential utility in bioimaging applications. 相似文献
136.
We study the radiative decays of the X(3872) in the charmonium-molecule model combined with the quark potential model. We obtain \({\Gamma(X(3872) \to J/\psi \, \gamma) = 29.2\,{\rm keV}}\) and \({\Gamma(X(3872) \to \psi' \, \gamma) = 6.3\,{\rm keV}}\) . The ratio of these two is 0.22, which is much smaller than the BABAR observation. We find that the result is very sensitive to the amount of the \({\chi_{c1}(1P)}\) component in the X(3872). 相似文献
137.
Shinobu Takizawa Tue Minh-Nhat Nguyen André Grossmann Michitaka Suzuki Dieter Enders Hiroaki Sasai 《Tetrahedron》2013,69(3):1202-1209
The acid–base organocatalyzed intramolecular Rauhut–Currier (RC) reaction of the dienone enolates has been developed. The enantioselective RC process produces the highly functionalized α-methylidene-γ-butyrolactones as a single diastereomer with up to 98% ee. 相似文献
138.
Masahiro Yoshida Takako Suzuki Hideharu Ishida Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(2):147-162
Abstract Three sialyl-Lex epitope analogs, which carry fucose and α-sialyl-(2→3)-galactose residues at O-2 and O-3, O-3 and O-2, and O-4 and O-6 positions of 1-deoxy-D-glucose backbone, respectively, have been synthesized. Glycosylation of 1,5-anhydro-4,6-O-benzylidene-D-glucitol (1) or 1,5-anhydro-6-O-benzoyl-2,3-di-O-benzyl-d-glucitol (4) prepared from 1,5-anhydro-d-glucitol, with methyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (5) using dimethyl(methylthio)sulfonium triflate (DMTST) as a promoter, afforded the corresponding fucosyl 1,5-anhydro-d-glucitol derivatives 7, 8 and 9. Glycosylation of 7, 8 or 10 derived from 9, with methyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-d-glyceroα-d-galacto-2-nonulopyranosylonate)-(2→3)-2,4,6-tri-O-benzoyl-1-thio-β-d-galactopyranoside (11) in the presence of DMTST gave the expected tetrasaccharide derivatives 12, 16 and 20. Hydrolysis of the benzylidene group in 12 and 16 gave compounds 13 and 17. Finally 13, 17 and 20 were transformed, by reductive removal of the benzyl groups, O-deacylation and subsequent hydrolysis of the methyl ester, into the sialyl-Lex epitope analogs 15, 19 and 22, respectively. 相似文献
139.
Eietsu Hasegawa Emi Tosaka Akira Yoneoka Yukinobu Tamura Shin-ya Takizawa Masaaki Tomura Yoshiro Yamashita 《Research on Chemical Intermediates》2013,39(1):247-267
Photoinduced electron-transfer reaction of α-bromomethyl-substituted benzocyclic β-keto esters with tertiary amines was investigated. Debrominated β-keto esters and ring-expanded γ-keto esters were obtained as major products. On the basis of mechanistic experiments it was concluded that these products are formed via a reaction sequence of selective carbon–bromine bond cleavage and subsequent competitive hydrogen abstraction and Dowd–Beckwith ring-expansion of the resulting primary alkyl radicals. The characteristic product distribution observed for the type of amine used is rationalized on the basis of selective reaction pathways of generated radical intermediates that depend on the nature of the amine radical cations. 相似文献
140.