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61.
Ryuta Nishida Katsuyoshi Kakinuma Hanako Nishino Takeo Kamino Hisao Yamashita Masahiro Watanabe Hiroyuki Uchida 《Solid State Ionics》2009,180(14-16):968-972
Aiming at SOFC anode applications, we have synthesized nanometer-sized nickel catalysts supported on hollow spherical particles of samaria-doped ceria (Ni/SDC) by spraying a mixed solution of nickel, samarium, and cerium nitrates into an atmospheric pressure plasma. The as-prepared particles consisted of SDC (average diameter dSDC = ca. 0.8 µm) and uniformly dispersed nanometer-sized NiO particles. When reduced in H2 at 800 °C or 1000 °C, Ni nanoparticles (average diameter dNi = 34 nm) were found to be embedded uniformly into the SDC surface. 相似文献
62.
Copper-mediated and copper-catalyzed cross-coupling of indoles and 1,3-azoles: double C-H activation
Nishino M Hirano K Satoh T Miura M 《Angewandte Chemie (International ed. in English)》2012,51(28):6993-6997
A new bronze age: the described copper-mediated cross-coupling with double C-H activation can provide a convergent access to indole-containing biheteroaryls that are of high interest in pharmaceutical and medicinal chemistry. In this strategy an easily attachable and detachable 2-pyrimidyl directing group is used. Moreover, a variant that is catalytic in copper is achieved by using atmospheric oxygen as an ideal co-oxidant. 相似文献
63.
Ishikita H Eger BT Okamoto K Nishino T Pai EF 《Journal of the American Chemical Society》2012,134(2):999-1009
In mammals, xanthine oxidoreductase can exist as xanthine dehydrogenase (XDH) and xanthine oxidase (XO). The two enzymes possess common redox active cofactors, which form an electron transfer (ET) pathway terminated by a flavin cofactor. In spite of identical protein primary structures, the redox potential difference between XDH and XO for the flavin semiquinone/hydroquinone pair (E(sq/hq)) is ~170 mV, a striking difference. The former greatly prefers NAD(+) as ultimate substrate for ET from the iron-sulfur cluster FeS-II via flavin while the latter only accepts dioxygen. In XDH (without NAD(+)), however, the redox potential of the electron donor FeS-II is 180 mV higher than that for the acceptor flavin, yielding an energetically uphill ET. On the basis of new 1.65, 2.3, 1.9, and 2.2 ? resolution crystal structures for XDH, XO, the NAD(+)- and NADH-complexed XDH, E(sq/hq) were calculated to better understand how the enzyme activates an ET from FeS-II to flavin. The majority of the E(sq/hq) difference between XDH and XO originates from a conformational change in the loop at positions 423-433 near the flavin binding site, causing the differences in stability of the semiquinone state. There was no large conformational change observed in response to NAD(+) binding at XDH. Instead, the positive charge of the NAD(+) ring, deprotonation of Asp429, and capping of the bulk surface of the flavin by the NAD(+) molecule all contribute to altering E(sq/hq) upon NAD(+) binding to XDH. 相似文献
64.
Local and global instabilities are investigated of wakes of general two-dimensional bluff bodies placed near and parallel to a plane boundary or ground. A spatio-temporal linear stability analysis is first applied to a four-parameter family of local wake profiles to investigate the fundamental local stability characteristics of the wake in ground effect. The analysis shows significant dependencies of the stability characteristics of the wake on the distance from the wake centreline to the ground (normalised by the wake width), and also on the velocity ratio of the near- and far-ground sides of the wake. The analysis is then compared with earlier experiments on a circular cylinder to examine, according to the transition scenario of the steep global modes, the streamwise variation of the local stability characteristics of the wake in ground effect. The comparison indicates that the near wake region of the cylinder changes from being absolutely unstable to being convectively unstable when the cylinder comes down into the near-ground range in which the von Kármán-type vortex shedding from the cylinder is suppressed, being qualitatively consistent with the transition scenario for general wake-type flows. A possible explanation is also given for the counter-intuitive relation between the thickness of the boundary layer on the ground and the critical gap distance for the cessation of the von Kármán-type vortex shedding in ground effect. 相似文献
65.
Cosmological solutions are investigated in six-dimensional, N = 2 supergravity Kaluza-Klein theory. It is shown that the solution of (the four-dimensional Friedmann universe)×(a constant S2) is the attractor, i.e. all the cosmological solutions starting from arbitrary initial conditions (apart from the time reversal ones) approach the above space-time asymptotically without any fine-tuning. The Friedmann solution is asymptotically “unique” in the later stage of the universe in six-dimensional N = 2 supergravity. 相似文献
66.
Finite and Infinite Systems of Interacting Diffusions: Cluster Formation and Universality Properties
We study some aspects of the relationship between the long time behaviour of systems with a finite but large number of components and their idealizations with countably many components. The following class of models is considered in detail, which contains examples occuring in population growth and population genetic models. 相似文献
67.
68.
Nishino T Okada M Kuroki T Watanabe T Nishiyama Y Sonoda N 《The Journal of organic chemistry》2002,67(24):8696-8698
A convenient synthetic method of unsymmetrical selenides has been developed. When diphenyl diselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl phenyl selenides were formed in moderate to good yields. For the reaction of primary alkyl chlorides and secondary alkyl iodides, the yields of the selenides were low; however, the yields were dramatically improved by the addition of TMEDA or HMPA. A reaction pathway involving the generation of a lanthanum phenylselenolate intermediate was suggested. 相似文献
69.
Shirafuji Tatsuru Nakagami Yuko Hayashi Yasuaki Nishino Shigehiro 《Plasmas and Polymers》1998,3(2):115-127
Fluorinated amorphous carbon films were prepared from tetrafluoroethylene (TFE; C2F4) and tetraisocyanatesilane (TICS; Si(NCO)4) using an RF plasma enhanced chemical vapor deposition method for the purpose of application to inter layer low permittivity films used in large scale integrated circuits. Structure of the deposited films was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Adhesion characteristics were examined by a tape-peel method. Permittivity of the films was investigated from capacitance measurement on metal-insulator-semiconductor structure. The structural analysis revealed that the deposited films contained imide-like group
in spite of the fact that TICS molecules contained isocyanate group
. The films deposited under the flow ratio TICS/(TFE + TICS) = 70% showed permittivity of 2.3, good adhesion on silicon substrates, and higher thermal stability than the films deposited without TICS. 相似文献
70.
Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed. 相似文献