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151.
J Choi M Fujitsuka S Tojo T Majima 《Journal of the American Chemical Society》2012,134(32):13430-13435
Pulse radiolysis is a powerful method to realize real-time observation of various redox processes, which induces various structural and functional changes occurring in biological systems. However, its application has been mainly limited to studies of the redox reactions of rather smaller biological systems such as DNA because of an undesired reaction due to various free radicals generated by pulse radiolysis. For application of pulse radiolysis to generate plenty of redox reactions of biological systems, selective redox reactions induced by electron pulses have to be developed. In this study, we report that in the presence of the high concentration of the denaturant, guanidine HCl (GdHCl), the selective reduction of the oxidized cytochrome c (Cyt c) takes place in time scales of a few microseconds by the electron transfer from the guanidine radical that is formed by the fast reaction of e(aq)(-) with GdHCl, consequently leading to folding kinetics of Cyt c. By providing insight into the folding dynamics of Cyt c, we show that the pulse radiolysis technique can be used to track the folding dynamics of various biomolecules in the presence of a denaturant including GdHCl. 相似文献
152.
Masataka Hakamada Fumi Hirashima Kota Kajikawa Mamoru Mabuchi 《Applied Physics A: Materials Science & Processing》2012,106(1):237-244
The magnetic moments of the fcc/fcc, hcp/hcp twin and fcc/hcp twin-like boundaries in cobalt were investigated by first-principles calculations based on density functional theory. The
magnetic moments in fcc/fcc were larger than those of the bulk fcc, while the variations in the magnetic moment were complicated in hcp/hcp and fcc/hcp. The magnetovolume effect on the magnetic moment at the twin(-like) boundaries was investigated in terms of the local average
atomic distance and the average deviation from equilibrium; however, the complicated variations in the magnetic moment could
not be explained from the magnetovolume effect. Next, the narrowing (or broadening) of the partial density of states (PDOS)
width of 3d orbitals, the number of occupied states for the spin-down channel, and the PDOS around the Fermi level were investigated.
The entire variation in the magnetic moment at the twin(-like) boundaries could be understood in terms of these factors. Charge
transfer occurred in hcp/hcp. In this case, the contributions of 4s and 4p electrons to the variation in the magnetic moment were relatively large. 相似文献
153.
First-principles fully relaxed tensile and shear test simulations were performed on Σ10(1124)/[1100] tilt Mg grain boundary (GB) models, with and without H segregation, to investigate mechanisms of H embrittlement of Mg. Strengthening as a result of covalent-like characteristics of Mg-H bonds prevailed over weakening of Mg-Mg bonds resulting from charge transfer; as a result, an H atom strengthened the GB. In addition, because the strong Mg-H bonds suppressed macroscopic GB fracture, elongation to failure was not reduced by H segregation. However, the resistance to GB shearing was increased by H segregation. It is therefore suggested that H segregation enhances crack growth at the GB, because dislocation emission from the crack tip is suppressed, resulting in H embrittlement of Mg. 相似文献
154.
Yasuhiro Isobe Hiromichi Ikki Tatsuyuki Sakakibara Motoaki Iwaya Tetsuya Takeuchi Satoshi Kamiyama Isamu Akasaki Takayuki Sugiyama Hiroshi Amano Mamoru Imade Yusuke Mori 《Journal of Crystal Growth》2012,351(1):126-130
We investigated unintentionally doped nonpolar a- and m-plane GaN layers grown by metalorganic vapor phase epitaxy under several sets of conditions on freestanding a- and m-plane GaN substrates. Oxygen contamination in a-plane GaN is greatly reduced by increasing the V/III ratio during growth. As a result, a high-resistivity GaN buffer layer for an AlGaN/GaN heterostructure field-effect transistor was realized. 相似文献
155.
Despite the recent advance in C-H bond functionalization chemistry, the C-H bonds in the acridine ring system, which is an important scaffold in medicinal and material science, have met with limited success, due, in part, to the lack of activated C-H bonds adjacent to the ring nitrogen atom. Herein, several protocols that can effect the regioselective arylation and alkylation of acridines at the C-4 and C-9 positions are described. 相似文献
156.
Noguchi M Nakamura M Ohno A Tanaka T Kobayashi A Ishihara M Fujita M Tsuchida A Mizuno M Shoda S 《Chemical communications (Cambridge, England)》2012,48(45):5560-5562
An efficient chemo-enzymatic process for construction of the α-linked disaccharide unit (GlcNAcα1-4Gal) found in gastric mucin has been developed. The process consists of a one-step preparation of a novel triazine type glycosyl donor in water and the subsequent transglycosylation to a galactose derivative catalysed by α-N-acetylglucosaminidase. 相似文献
157.
Mamoru Tobisu Ayaka Yasutome Ken Yamakawa Toshiaki Shimasaki Naoto Chatani 《Tetrahedron》2012,68(26):5157-5161
Ni(0)/NHC-based catalyst system can promote the amination of N-heteroaryl methyl ethers via the cleavage of normally unreactive carbon–oxygen bonds. Electron-deficient N-heteroarenes including pyridine, quinoline, isoquinoline, and quinoxaline undergo amination to afford aminopyridine and related heteroarenes, which constitute an important class of compounds. 相似文献
158.
S Kurimoto K Suzuki M Okasaka Y Kashiwada OK Kodzhimatov Y Takaishi 《Chemical & pharmaceutical bulletin》2012,60(7):913-919
Seven new sesquiterpene lactone glycosides (1-7) were isolated from the H2O-soluble fraction from the MeOH extract of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations of compounds 1 and 2 were determined by modified Mosher's method. 相似文献
159.
Pravin Sawant Mamoru Ishii Michitsugu Mori 《International Journal of Heat and Fluid Flow》2009,30(4):715-728
Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air–water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam–water annular flow conditions. In each experiment, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using the liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant [Sawant, P.H., Ishii, M., Mori, M., 2008. Droplet entrainment correlation in vertical upward co-current annular two-phase flow. Nucl. Eng. Des. 238 (6), 1342–1352] for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible.Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air–water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air–water, helium–water and air–genklene experimental data measured by Willetts [Willetts, I.P., 1987. Non-aqueous annular two-phase flow. D.Phil. Thesis, University of Oxford]. However, comparison of the correlations with the steam–water data available in literature showed significant discrepancies. It is proposed that these discrepancies might have been caused due to the inadequacy of the liquid film extraction method used to measure the entrainment fraction or due to the change in mechanism of entrainment under high liquid flow conditions. 相似文献
160.
Naoko Asakuma Toshimi Fukui Mamoru Aizawa Motoyuki Toki Hiroaki Imai Hiroshi Hirashima 《Journal of Sol-Gel Science and Technology》2000,19(1-3):333-336
Structural changes stimulated by ultraviolet (UV) laser irradiations of sol-gel derived inorganic oxide films were investigated. Dried gel films of TiO2, Nb2O5, Ta2O5, SrTiO3 and Pb(Zr
x
Ti1–x
)O3 (PZT) were found to be crystallized by the laser irradiation. On the other hand, the photo-induced change in gel films of BaTiO3, LiNbO3 and LiTaO3 was not observed although the laser beams were absorbed in the films. These sol-gel films were thermally crystallized at almost the same temperature around 600–700°C except TiO2. Thus, the UV-laser-induced crystallization is not directly ascribed to a simple thermal effect with the irradiation. Photochemical properties of the cations are assumed to be important for the change in sol-gel films. 相似文献