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91.
Saki Sonoda Yoshiyuki Yamamoto Ken-chi Suga Hidenobu Hori 《Solid State Communications》2005,133(3):177-182
Local electronic structures around Ga and Mn in Mn-doped GaN film with Tc of 940 K are investigated by K X-ray absorption near edge structure (XANES) analysis. It was found that the shape of the Ga XANES spectrum is remarkably similar to that of the un-doped GaN film indicating that the local electronic structure around Ga is not disturbed with Mn doping. As for the Mn XANES spectra, obvious pre-edge peaks were observed: the fine structures in the pre-edges correspond with calculated Mn 3d partial density of states which predict impurity band formation with the Fermi energy stays in the spin-up band. These findings imply that Mn 3d levels stay within the gap with the Fermi energy stays in the spin-up band. 相似文献
92.
Kojima Chie Watanabe Kenji Murata Hidenobu Nishio Yuki Makiura Rie Matsunaga Katsuyuki Nakahira Atsushi 《Research on Chemical Intermediates》2019,45(1):23-32
Research on Chemical Intermediates - Hydroxyapatite (HA) is a biocompatible and porous material that is useful for gene delivery. In this study, various Zn- and Mg-doped HA samples were produced by... 相似文献
93.
Tamiya M Ohmori K Kitamura M Kato H Arai T Oorui M Suzuki K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(35):9791-9823
A general approach to the regio- and stereoselective total synthesis of the benanomicin-pradimicin antibiotics (BpAs) is described. Construction of the aglycon has been achieved by 1) the diastereoselective ring-opening of a biaryl lactone by using (R)-valinol as a chiral nucleophile and 2) the stereocontrolled semi-pinacol cyclization of the aldehyde acetal by using SmI(2) in the presence of BF(3)OEt(2) and a proton source to afford the ABCD tetracyclic monoprotected diol. This strategy enabled us to control the two stereogenic sites in the B ring (C-5 and C-6) and the regioselective introduction of the carbohydrate moiety. The ABCD tetracycle could serve as an ideal platform for the divergent access to various BpAs. The amino acid (D-alanine) was introduced onto the ABCD tetracycle. Glycosylation was promoted by the combination of Cp(2)HfCl(2) and AgOTf (1:2 ratio). Construction of the E ring followed by deprotection completed the first total synthesis of benanomicin A (2 a), benanomicin B (2 b), and pradimicin A (1 a). The route is flexible enough to allow the synthesis of other congeners differing in their amino acid and carbohydrate moieties. 相似文献
94.
Toward Naphthocyclinones: Doubly Connected Octaketide Dimers with a Bicyclo[3.2.1]octadienone Core by Thiolate‐Mediated Cyclization 下载免费PDF全文
Dr. Yoshio Ando Subaru Hori Takumi Fukazawa Prof. Dr. Ken Ohmori Prof. Dr. Keisuke Suzuki 《Angewandte Chemie (International ed. in English)》2015,54(33):9650-9653
A viable method is reported for the synthesis of the bicyclo[3.2.1]octadienone scaffold in naturally occurring octaketide dimers. The procedure employs a reductive cyclization reaction mediated by an unusual ethanedithiol monosodium salt. 相似文献
95.
The photolysis of iron carbonyl (Fe(CO)5) adsorbed on titanium dioxide (TiO2, anatase) was studied by FT-IR spectroscopy. When adsorbed Fe(CO)5 is illuminated by visible and near-UV light, the IR spectrum of its photolysis products is hardly observed, indicating that most of the Fe(CO)5 is photodecomposed to iron(0) or iron oxides on TiO2. The carbon monoxide (CO) evolution rate upon illumination depends on the wavelength of light; 433 nm light is more effective for CO evolution than 366 nm light. This result implies that the band-gap excitation of TiO2 has little effect on the photolysis of adsorbed Fe(CO)5, since the absorption edge of TiO2 (anatase) lies at around 400 nm. The effects of substrates on the photolysis of adsorbed Fe(CO)5 are discussed with reference to previous results obtained for aluminium oxide (Al2O3) and silicon dioxide (SiO2), on which the photolysis leads to the formation of Fe2(CO)9 or Fe3(CO)12. 相似文献
96.
97.
S. Tomiyoshi H. Yoshida H. Ohmori T. Kaneko H. Yamamoto 《Journal of magnetism and magnetic materials》1987,70(1-3):247-248
Temperature variations of resistivities are measured on the single crystals of Mn3Sn with a hexagonal crystal structure. Anomalies of resistivity along the c-axis are observed at 230 and 420 K which correspond to the transition temperature from a tringle-helix to triangular spin structure state and the Néel temperature, respectively. 相似文献
98.
99.
Hidenobu Tsuji Takayuki Nakano Yoshihiro Matsumoto Shumpei Kameyama 《Optical Review》2016,23(2):155-160
We have developed an illumination optical system for 3D imaging ladar (laser detection and ranging) which forms flattop beam shape by transformation of the Gaussian beam in the wide distance range. The illumination is achieved by beam division and recombination using a prism and a negative powered lens. The optimum condition of the transformation by the optical system is derived. It is confirmed that the flattop distribution can be formed in the wide range of the propagation distance from 1 to 1000 m. The experimental result with the prototype is in good agreement with the calculation result. 相似文献
100.
Characterization and mechanistic study of a radical SAM dehydrogenase in the biosynthesis of butirosin 总被引:1,自引:0,他引:1
Yokoyama K Numakura M Kudo F Ohmori D Eguchi T 《Journal of the American Chemical Society》2007,129(49):15147-15155
BtrN encoded in the butirosin biosynthetic gene cluster possesses a CXXXCXXC motif conserved within the radical S-adenosyl methionine (SAM) superfamily. Its gene disruption in the butirosin producer Bacillus circulans caused the interruption of the biosynthetic pathway between 2-deoxy-scyllo-inosamine (DOIA) and 2-deoxystreptamine (DOS). Further, in vitro assay of the overexpressed enzyme revealed that BtrN catalyzed the oxidation of DOIA under the strictly anaerobic conditions along with consumption of an equimolar amount of SAM to produce 5'-deoxyadenosine, methionine, and 3-amino-2,3-dideoxy-scyllo-inosose (amino-DOI). Kinetic analysis showed substrate inhibition by DOIA but not by SAM, which suggests that the reaction is the Ordered Bi Ter mechanism and that SAM is the first substrate and DOIA is the second. The BtrN reaction with [3-2H]DOIA generated nonlabeled, monodeuterated and dideuterated 5'-deoxyadenosines, while no deuterium was incorporated by incubation of nonlabeled DOIA in the deuterium oxide buffer. These results indicated that the hydrogen atom at C-3 of DOIA was directly transferred to 5'-deoxyadenosine to give the radical intermediate of DOIA. Generation of nonlabeled and dideuterated 5'-deoxyadenosines proved the reversibility of the hydrogen abstraction step. The present study suggests that BtrN is an unusual radical SAM dehydrogenase catalyzing the oxidation of the hydroxyl group by a radical mechanism. This is the first report of the mechanistic study on the oxidation of a hydroxyl group by a radical SAM enzyme. 相似文献