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151.
Taira Okita Yingjuan Yang Junichi Hirabayashi Mitsuhiro Itakura Katsuyuki Suzuki 《哲学杂志》2016,96(15):1579-1597
To elucidate the effect of stacking fault energies (SFEs) on defect formation by the collision cascade process for face-centred cubic metals, we used six sets of interatomic potentials with different SFEs while keeping the other properties almost identical. Molecular dynamic simulations of the collision cascade were carried out using these potentials with primary knock-on atom energies (EPKA) of 10 and 20 keV at 100 K. Neither the number of residual defects nor the size distributions for both self-interstitial atom (SIA) type and vacancy type clusters were affected by the difference in the SFE. In the case of EPKA = 20 keV, the ratio of glissile SIA clusters increased as the SFE decreased, which was not expected by a prediction based on the classical dislocation theory. The trend did not change after annealing at 1100 K for 100 ps. For vacancy clusters, few stacking fault tetrahedrons (SFTs) formed before the annealing. However, lower SFEs tended to increase the SFT fraction after the annealing, where large vacancy clusters formed at considerable densities. The findings of this study can be used to characterise the defect formation process in low SFE metals such as austenitic stainless steels. 相似文献
152.
Kazuaki Taira 《Annali dell'Universita di Ferrara》2010,56(2):369-392
The purpose of this paper is to study a class of semilinear degenerate elliptic boundary value problems at resonance which include as particular cases the Dirichlet and Robin problems. The approach here is based on the global inversion theorems
between Banach spaces, and is distinguished by the extensive use of the ideas and techniques characteristic of the recent
developments in the theory of partial differential equations. By making use of the Lyapunov–Schmidt procedure and the global
inversion theorem, we prove existence and uniqueness theorems for our problem. The results here extend an earlier theorem
due to Landesman and Lazer to the degenerate case. 相似文献
153.
Shizuka Saito 《Tetrahedron letters》2007,48(22):3809-3812
Two new Daphniphyllum alkaloids, calyciphyllines E (1) and F (2), have been isolated from the leaves of Daphniphyllum calycinum (Daphniphyllaceae), and the structures and relative stereochemistry were elucidated on the basis of spectroscopic data. 相似文献
154.
Six new Daphniphyllum alkaloids, calyciphyllines H-M (1-6), were isolated from the leaves and stems of Daphniphyllum calycinum (Daphniphyllaceae). The structures and relative stereochemistry of 1-6 were elucidated on the basis of spectroscopic data, and the absolute stereochemistry of 3 was assigned by PGME method. 相似文献
155.
Calyciphylline C (1), a novel Daphniphyllum alkaloid with unprecedented fused-hexacyclic ring system, has been isolated from the leaves of Daphniphyllum calycinum (Daphniphyllaceae), and the structure and relative stereochemistry were elucidated on the basis of spectroscopic data. 相似文献
156.
Hideaki Uchida Yohsuke Taira Takeshi Yasumoto 《Rapid communications in mass spectrometry : RCM》2013,27(17):1999-2008
157.
Hitoshi Tamiaki Nobutaka Ariki Haruka Sugiyama Yoshichika Taira Yusuke Kinoshita Tomohiro Miyatake 《Tetrahedron》2013
Methyl 20-bromo-pyropheophorbide-a possessing a vinyl group at the 3-position and its analogs having 3-ethyl, 3-(1-hydroxyethyl) and 3-acetyl groups were prepared by modifying naturally occurring chlorophyll(Chl)-a. The 20-bromo-chlorins were cross-coupled with vinyl- and 1-ethoxyvinyl-tributyltins in the presence of a Pd(0) catalyst to afford 20-vinyl- and acetyl-chlorins, respectively. The interconversions among the above four C2-functional groups at the 3-position were readily performed in the semi-synthetic Chl derivatives, but no modification of the 20-vinyl and acetyl groups was observed. The difference of the chemical reactivity is ascribable to the steric factor: the 31-position was less sterically hindered than the 201-position. Single hydrogenation and hydration of 3,20-divinyl-chlorin and reduction of 3,20-diacetylchlorin proceeded exclusively at the 3-position. The redmost (Qy) bands in electronic absorption spectra of the semi-synthetic Chl derivatives in a diluted dichloromethane solution were controlled by the 3,20-substituents. The 3-substituent effect on their Qy maxima was determined by the electronic factor (their electronegativity), while the 20-substituent effect was primarily dependent on the steric factor (their local size). 相似文献
158.
Kawasaki T Okano Y Suzuki E Takano S Oji S Soai K 《Angewandte Chemie (International ed. in English)》2011,50(35):8131-8133
Trigger happy: Chiral oxygen isotopomers of hydrobenzoin ([(18) O](R)-1 and [(18) O](S)-1) acted as chiral triggers to induce the enantioselective addition of iPr(2) Zn to pyrimidine-5-carbaldehyde. An extremely small chiral influence arising from the presence of the oxygen isotope ((18) O) is amplified through asymmetric autocatalysis to enantioenrich the 5-pyrimidyl alkanol product. 相似文献
159.
BNS-22, a chemically synthesized derivative of the natural plant product GUT-70, has antiproliferative activity against human cancer cells, the mechanism of which is unknown. Here, we identify a target of BNS-22 by proteomic profiling analysis, which suggests that BNS-22 belongs to the same cluster as ICRF-193, a DNA topoisomerase II (TOP2) catalytic inhibitor. BNS-22 inhibits kinetoplast DNA decatenation that is mediated by human TOP2α and TOP2β in?vitro at an IC(50) of 2.8 and 0.42?μM, respectively. BNS-22 does not affect DNA damage and antagonizes TOP2 poison-mediated DNA damage. Like ICRF-193, BNS-22 induces mitotic abnormalities, characterized by impairments in chromosome alignment and segregation, thereby causing polyploidy in HeLa cells. These results indicate that BNS-22 targets TOP2 and acts as its catalytic inhibitor. 相似文献
160.
Yan L Nakayama S Yitbarek S Greenfield I Sintim HO 《Chemical communications (Cambridge, England)》2011,47(1):200-202
Herein, we demonstrate how to detect nucleic acids that do not contain restriction endonuclease recognition sites with restriction endonucleases. We show that the topology of DNA probes used in this detection strategy remarkably affects the efficiency of RNA/DNA detection. 相似文献