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101.
S Ohmori K Nakata K Nishihara S Yamamoto M Kawase S Tsuboi 《Journal of chromatography. A》1992,574(1):35-40
Cystathionine was cleaved into 2-ketobutyric acid, cysteine and ammonia by cystathionase. 2-Ketobutyric acid was converted into 3-ethyl-2-hydroxy-6,7-dimethoxyquinoxaline (EHDQ) by reaction with 1,2-diamino-4,5-dimethoxybenzene. When EHDQ was measured in a mobile phase of pH 2.1 using high-performance liquid chromatography with ultraviolet detection, 250 pmol of L-cystathionine in 250 microliters of the reaction mixture could be determined. Because EHDQ has a strong fluorescence in a mobile phase of pH 6.5 at 447 nm, on excitation at 365 nm, as little as 2.5 pmol of cystathionine in 250 microliters of the reaction mixture could be determined by high-performance liquid chromatography with fluorimetric detection. Cystathionase activity was assayed on the basis of the same principle by determining cystathionine in as little as 63 ng of rat liver by fluorimetric detection. Cystathionine beta-synthase activity was measured by the same method by determining cystathionine formed in only 113 ng of wet weight of rat liver. Using these methods, both cystathionine beta- and gamma-lyase activities in Saccharomyces cerevisiae were determined, because quinoxaline derivatives from pyruvate and 2-ketobutyrate could be measured simultaneously by high-performance liquid chromatography. 相似文献
102.
Kazuya Hayata 《Optical Review》1997,4(2):303-304
It is shown that, at a critical point where the effective refractive index of a mode coincides with the bulk index of a cladding region, optical waveguide modes exhibiting a lognormal feature are supportable for a hyperlongrange refractive-index profile. As a typical example of waveguides that support lognormal modes a parabolic-index core surrounded by a depressed-index cladding is presented. 相似文献
103.
Akito Tsuboi 《Mathematical Logic Quarterly》1992,38(1):101-106
In this note we treat maximal and minimal normal subgroups of a superstable group and prove that these groups are definable under certain conditions. Main tool is a superstable version of Zil'ber's indecomposability theorem. MSC: 03C60. 相似文献
104.
Dr. Yasuhide Akizuki Dr. Ikuya Yamada Dr. Koji Fujita Kazuya Taga Dr. Takateru Kawakami Dr. Masaichiro Mizumaki Prof. Katsuhisa Tanaka 《Angewandte Chemie (International ed. in English)》2015,54(37):10870-10874
Of particular interest is a peculiar motion of guest atoms or ions confined to nanospace in cage compounds, called rattling. While rattling provides unexplored physical properties through the guest–host interactions, it has only been observed in a very limited class of materials. Herein, we introduce an A‐site‐ordered quadruple perovskite, CuCu3V4O12, as a new family of cage compounds. This novel AA′3B4O12‐type perovskite has been obtained by a high‐pressure synthesis technique and structurally characterized to have cubic Im$\bar 3$ symmetry with an ionic model of Cu2+Cu2+3V4+4O12. The thermal displacement parameter of the A‐site Cu2+ ion is as large as Uiso≈0.045 Å2 at 300 K, indicating its large‐amplitude thermal oscillations in the oversized icosahedral cages. Remarkably, the presence of localized phonon modes associated with rattling of the A‐site Cu2+ ion manifests itself in the low‐temperature specific heat data. This work sheds new light on the structure–property relations in perovskites. 相似文献
105.
Dr. Shinichiro Fuse Ayako Ikebe Kazuya Oosumi Tomoya Karasawa Keisuke Matsumura Dr. Miho Izumikawa Dr. Kohei Johmoto Dr. Hidehiro Uekusa Dr. Kazuo Shin‐ya Prof. Takayuki Doi Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9454-9460
An asymmetric total synthesis of ent‐pyripyropene A was achieved by a convergent synthetic route. We used our originally developed TiIII‐catalyzed radical cyclization to construct an AB‐ring portion that consisted of a trans‐decalin skeleton with five contiguous stereogenic centers. The coupling between the AB‐ring and the DE‐ring portions, and a subsequent C‐ring cyclization, led to the total synthesis of ent‐pyripyropene A. An evaluation of the insecticidal activity of ent‐pyripyropene A against two aphid species revealed that ent‐pyripyropene A was 35–175 times less active than naturally occurring pyripyropene A. This result indicated that the biological target of pyripyropene A recognizes the absolute configuration of pyripyropene A. 相似文献
106.
Liu B Nakata K Sakai M Saito H Ochiai T Murakami T Takagi K Fujishima A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8500-8508
A facile new method that combines electrospray and hydrothermal treatment is used to prepare mesoporous core-shell TiO(2) spheres with high specific surface areas and high pore volumes. Interestingly, the resulting TiO(2) spheres are composed of anatase TiO(2) nanocrystals with exposed step-like {001} and smooth {010} facets. The percentage of exposed {001} facets can be adjusted by changing the experimental parameters used in the electrospray and hydrothermal treatment processes, such as the contents of poly(N-vinyl-2-pyrrolidone) and acetic acid. The combination of high specific surface area (>100 m(2) g(-1)), high pore volume (>0.30 cm(3) g(-1)), useful pore size (10-15 nm), spherical core-shell structure, and exposed high energy facets makes these TiO(2) spheres an important candidate for use in many photoelectrochemical applications. The formation mechanism of the mesoporous TiO(2) spheres is also studied. The great advantage of this method is that interesting and complicated mesoporous superstructures can be prepared using electrospray technology. 相似文献
107.
Highly photoluminescent nanocrystals based on a gold(I) complex and their electrophoretic patterning
Saitoh M Balch AL Yuasa J Tada K Onoda M Nakashima T Kawai T 《Langmuir : the ACS journal of surfaces and colloids》2011,27(17):10947-10952
The fabrication of nanocrystals (NCs) composed of the cationic Au(I) complex was demonstrated by the reprecipitation method in which the colloidal solution of the NCs showed brilliant green phosphorescence with a quantum yield of 83% in n-hexane. Characterization of the prepared NCs was performed by transmission electron microscopy observation and elemental analysis with energy-dispersive X-ray spectroscopy. The obtained Au(I) NCs were particles of random shapes with a diameter of 200-400 nm. The selected-area electron diffraction and X-ray diffraction measurements showed the characteristic diffraction patterns attributable to the crystal structure of the bulk crystal of the Au(I) complex. A similar method was performed with a different counteranion, leading to a colloidal solution of the microcrystals (MCs) with brilliant yellow phosphorescence and a quantum yield of 26% in n-hexane. Luminescence patterning of the NCs and MCs was also achieved successfully by electrophoretic deposition onto an indium tin oxide (ITO)-coated glass substrate, resulting in characteristic luminescence patterns on the ITO substrates with relatively high photoluminescence quantum yields. 相似文献
108.
Kashiwada A Tsuboi M Matsuda K 《Langmuir : the ACS journal of surfaces and colloids》2011,27(4):1403-1408
The coiled coil trimer structure is a common motif observed in membrane fusion processes of specific fusion proteins such as the hemagglutinin glycoprotein. The HA2 subunit in the hemagglutinin changes its conformation or geometry to be favorable to membrane fusion in response to endosomal weakly acidic pH. This pH responsiveness is indispensable to an artificial polypeptide-triggered delivery system as well as the membrane fusion reaction in biology. In this study, we have constructed an AAB-type coiled coil heteroassembled system that is sensitive to weakly acidic pH. The heterotrimer is formed from two kinds of polypeptides containing an Ala or a Trp residue at a hydrophobic a position, and it was observed that the Glu residue at the other a position induced an acidic pH-dependent conformational change. On the basis of this pH-responsive coiled coil heteroassembled system, a boronic acid coupled working polypeptide for the combination of an intervesicular complex with a sugarlike compound on the surface of the target liposome, and a supporting polypeptide for the construction of a pH-responsive heterotrimer with the working polypeptide were designed and synthesized. The process of membrane fusion was characterized by lipid-mixing, inner-leaflet lipid-mixing, and content-mixing assays. The target selective vesicle fusion is clearly observed at a weakly acidic pH, where the working polypeptides form a heterotrimeric coiled coil with the supporting polypeptides in a 1:2 binding stoichiometry and the surfaces between pilot and target vesicles come into close proximity to each other. 相似文献
109.
Mitsumoto K Oshiro E Nishikawa H Shiga T Yamamura Y Saito K Oshio H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(35):9612-9618
Cyanide‐bridged metal complexes of [Fe8M6(μ‐CN)14(CN)10 (tp)8(HL)10(CH3CN)2][PF6]4?n CH3CN?m H2O (HL=3‐(2‐pyridyl)‐5‐[4‐(diphenylamino)phenyl]‐1H‐pyrazole), tp?=hydrotris(pyrazolylborate), 1 : M=Ni with n=11 and m=7, and 2 : M=Co with n=14 and m=5) were prepared. Complexes 1 and 2 are isomorphous, and crystallized in the monoclinic space group P21/n. They have tetradecanuclear cores composed of eight low‐spin (LS) FeIII and six high‐spin (HS) MII ions (M=Ni and Co), all of which are bridged by cyanide ions, to form a crown‐like core structure. Magnetic susceptibility measurements revealed that intramolecular ferro‐ and antiferromagnetic interactions are operative in 1 and in a fresh sample of 2 , respectively. Ac magnetic susceptibility measurements of 1 showed frequency‐dependent in‐ and out‐of‐phase signals, characteristic of single‐molecule magnetism (SMM), while desolvated samples of 2 showed thermal‐ and photoinduced intramolecular electron‐transfer‐coupled spin transition (ETCST) between the [(LS‐FeII)3(LS‐FeIII)5(HS‐CoII)3(LS‐CoIII)3] and the [(LS‐FeIII)8(HS‐CoII)6] states. 相似文献