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21.
Kuno A. Zheng G. D. Matsuo M. Takano B. Shi J. A. Wang Q. 《Hyperfine Interactions》2002,141(1-4):321-326
In this study, 57Fe Mössbauer spectroscopy has been applied to sediments collected from Qinghai Lake in Qinghai Province, China, to investigate the vertical distribution of iron species. Their Mössbauer spectra consisted of four doublets ascribable to one paramagnetic high-spin Fe3+, two paramagnetic high-spin Fe2+ with different quadrupole splittings, and one diamagnetic low-spin Fe2+ that corresponds to pyrite (FeS2). The distribution of pyrite suggested climatic changes during the past nine thousand years. It was demonstrated that the iron speciation in the salt lake sediments by Mössbauer spectroscopy can be used to reconstruct the past environment.
相似文献22.
D. Moromachi A. Kuno M. Matsuo 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(2):495-498
In order to investigate the transition of tidelands, we collected sediments in Yatsu tideland and Nekozane river mouth in Tokyo Bay. The vertical distributions of elements were determined by instrumental neutron activation analysis and prompt gamma-ray analysis. In Yatsu tideland the vertical distribution changed in a great extent, which was considered as an influence of the neighboring reclamation. They were categorized into four groups, and two parameters were created by applying principal component analysis. Chemical states of iron and sulfur were also investigated by Mössbauer spectroscopy and X-ray absorption fine structure. These results show that Yatsu tideland became an anaerobic environment. 相似文献
23.
Synthesis and mesomorphic behavior of nine members of each of the two classes of 6-phenyl- and 2-phenyltetralins and five members of the 2-trans-cyclohexyltetralins are reported. The synthesis of one member of each class is described in detail. Besides the target compounds, more than twenty intermediates showed liquid crystalline properties; their transition temperatures are recorded (see Tables 1-6). 相似文献
24.
Y. Kuno J. Imazato K. Nishiyama K. Nagamine T. Yamazaki K. Matsuta S. Ise Y. Nojiri T. Minamisono 《Hyperfine Interactions》1988,39(3):253-267
NMR measurements on12B nuclei implanted in a thin sheet of highly oriented pyrolytic graphite (Grafoil) have been made to study the magnitude of
the polarization of12B and its electric quadrupole coupling. The magnitude of the residual polarization of12B held in carbon material is of crucial importance to the experiment measuring the average polarization of12B produced in the muon capture by12C. It was found that the polarization of12B can be maintained at 101.0±2.2% in Grafoil under a magnetic field of 3 kG. The electric quadrupole coupling was determined
to bee
2
qQ/h=+1207.3±8.2 kHz. From the magnitude and the sign of the electric field gradienteq, the location of12B was found to be a substitutional site in the carbon lattice. The anomalous B-C bond involving thesp
2
hybrid orbitals with partially filledp
z
electrons is also discussed. 相似文献
25.
26.
Niklaus Hriger Dobrila
ivanov Horst H. A. Linde Kuno Meyer 《Helvetica chimica acta》1972,55(7):2549-2562
From the toad venom Ch'an Su the bufadienolides 1, 4, 9, 10, 12, 15, 17, 20, 22, 25 and 18 , the latter as diacetate 19 were isolated and their structure elucidated. 相似文献
27.
T. Kondow Y. Kuno R. Kadono J. Imazato K. Nagamine T. Yamazaki 《Physics letters. A》1985,110(6):319-322
The precession frequencies of negative-muon spin rotation in highly oriented pyrolytic graphite and its second stage Rb compound were measured at room temperature. The results showed that a μ- C-C bond is formed from sp2 hybrid orbitals involving the partially filled pz orbital and that intercalation influences the σ as well as the π bonds. 相似文献
28.
29.
Inversion of Optical Activity in the Synthesis of Mercury Sulfide Nanoparticles: Role of Ligand Coordination
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Jumpei Kuno Prof. Yutaka Imamura Dr. Michio Katouda Dr. Motomichi Tashiro Prof. Tsuyoshi Kawai Dr. Takuya Nakashima 《Angewandte Chemie (International ed. in English)》2018,57(37):12022-12026
Optical activity in inorganic colloidal materials was controlled through interactions of chiral molecules with the nanoparticle (NP) surface. An inversion of optical activity in the synthesis of mercury sulfide (HgS) NPs was demonstrated with an intrinsically chiral crystalline system in the presence of an identical chiral capping ligand. A continuous decrease in the positive first Cotton effect and an eventual reversal of CD profile were observed upon heating the aqueous solution of HgS NPs capped with N‐acetyl‐l ‐cysteine (Ac‐l ‐Cys) at 80 °C. Ac‐l ‐Cys afforded two bidentate coordination configurations with an almost mirror image of each other using the thiolate and either of carboxylate or acetyl–carbonyl groups on the HgS core. Experiment and calculation suggest that a shift in the distribution of the NP formation with energy in response to the combinations of ligand coordination structure and chiral crystalline surface is responsible for the inversion of optical activity. 相似文献