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101.
102.
A new method for handling volatile liquids in the ultramicrodetermination of nitrogen by the sealed-tube method, using a weighing tube of thin-walled capillary containing a capillary of sample, is described. Before sealing the weighing tube, the air present can be replaced with a gas mixture of CO2 and CH4 having approximately the density of air. The weighing tube is broken by tapping prior to combustion, and analysis is not affected by volatilization. 相似文献
103.
104.
H. Watanabe Kunihiro Osaki Mutsuo Matsumoto Dobrin P. Bossev Cathy E. McNamee Masaru Nakahara Ming-Long Yao 《Rheologica Acta》1998,37(5):470-485
Nonlinear rheological features were investigated for an aqueous solution of tetraethylammonium perfluorooctyl sulfonate (C8F17SO3
–N+(C2H5)4; abbreviated as FOSTEA). In the solution (c=0.045 mol/l; 28.3 g/l), spherical micelles of FOSTEA were connected with each other to form threads of pearl-necklace shape.
These threads were further organized into a transient network to exhibit linear relaxation characteristic of living polymers,
single-mode terminal relaxation widely separated from faster relaxation processes. Nonlinear relaxation experiments against
large step-strains γ(≤8) revealed that the terminal relaxation mode had a γ-insensitive relaxation time but its relaxation
intensity exhibited significant damping (much stronger than that for entangled polymers). In contrast, the relaxation time
and intensity for the fast relaxation modes first increased and then decreased with increasing γ. Under shear flow, the FOSTEA
threads exhibited strong thinning of the viscosity. These nonlinear features of the FOSTEA threads were compared with those
of other threadlike micelles, analyzed on the basis of an empirically introduced constitutive equation, and discussed in relation
to strain/low-induced scission of the living threads.
Received: 20 February 1998 Accepted: 30 July 1998 相似文献
105.
Kunihiro Kuwajima Maho Yagi-Utsumi Saeko Yanaka Koichi Kato 《Molecules (Basel, Switzerland)》2022,27(12)
Hydrogen/deuterium (H/D) exchange combined with two-dimensional (2D) NMR spectroscopy has been widely used for studying the structure, stability, and dynamics of proteins. When we apply the H/D-exchange method to investigate non-native states of proteins such as equilibrium and kinetic folding intermediates, H/D-exchange quenching techniques are indispensable, because the exchange reaction is usually too fast to follow by 2D NMR. In this article, we will describe the dimethylsulfoxide (DMSO)-quenched H/D-exchange method and its applications in protein science. In this method, the H/D-exchange buffer is replaced by an aprotic DMSO solution, which quenches the exchange reaction. We have improved the DMSO-quenched method by using spin desalting columns, which are used for medium exchange from the H/D-exchange buffer to the DMSO solution. This improvement has allowed us to monitor the H/D exchange of proteins at a high concentration of salts or denaturants. We describe methodological details of the improved DMSO-quenched method and present a case study using the improved method on the H/D-exchange behavior of unfolded human ubiquitin in 6 M guanidinium chloride. 相似文献
106.
Kana Kunihiro Dr. Svetlana Heyte Prof. Dr. Sébastien Paul Dr. Thierry Roisnel Prof. Dr. Jean-François Carpentier Dr. Evgueni Kirillov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):3997-4003
A series of in situ-prepared catalytic systems incorporating RuII precursors and bidentate phosphine ligands has been probed in the reductive carboxylation of ethylene in the presence of triethylsilane as reductant. The catalytic production of propionate and acrylate silyl esters was evidenced by high-throughput screening (HTS) and implemented in batch reactor techniques. The most promising catalyst systems identified were made of Ru(H)(Cl)(CO)(PPh3)3 and 1,4-bis(dicyclohexylphosphino)butane (DCPB) or 1,1’-ferrocene-diyl-bis(cyclohexylphosphine) (DCPF). A marked influence of water on the acrylate/propionate selectivity was noted. Turnover numbers [mol mol(Ru)−1] up to 16 for acrylate and up to 68 for propionate were reached under relatively mild conditions (20 bar, 100 °C, 0.5 mol % Ru, 40 mol % H2O vs. HSiEt3). Possible mechanisms are discussed. 相似文献
107.
Kunihiro Ichimura 《Journal of polymer science. Part A, Polymer chemistry》1984,22(11):2817-2828
A method to immobilize enzymes photochemically with use of photocrosslinkable poly(vinylalcohol) bearing stilbazolium groups is described. Irradiation of a film of the photosensitive polymer containing enzyme gave water-insoluble, cellophane-like transparent film demonstrating high enzyme activity. The dissolution of enzymes from the film was dependent upon the molecular weight of the proteins and the content of the photocrosslinking unit. It was found that various enzymes are sufficiently entrapped in the photocrosslinked polymer matrix when the content of the photosensitive group is more than about 1.0 mol%. 相似文献
108.
Isao Kitagawa Hirotaka Shibuya Hiromichi Fujioka Yoshio Yamamoto Akiharu Kajiwara Kunihiro Kitamura Ayako Miyao Toshio Hakoshima Ken-ichi Tomita 《Tetrahedron letters》1980,21(20):1963-1966
Acid treatment of (IR, 3S,1′S)-1-(1′,2′-Epoxyethyl)-1,2,2-trimethyl-3-acetoxymethyl-cyclopentane ) has been shown to yield three products (, , ), among which and are 1-oxa-bicyclo[3.3.0]octane derivatives formed successive methyl migrations followed by an oxorane ring closure. 相似文献
109.
Novel benzamide derivatives, N-[1-(aminocarbonyl)-2-(1-piperidinyl)ethyl]benzamides (4 and 5), were prepared from the reaction of beta-piperidinoalanine (6) as the starting material. 相似文献
110.
Haruhisa Akiyama Kazuaki Kudo Kunihiro Ichimura 《Macromolecular rapid communications》1995,16(1):35-41
Polymethacrylates with laterally attached azobenzenes were prepared to cause molecular reorientation of this chromophore in their thin films by linearly polarized irradiation with an exposure energy of less than ca. 100 mJ/cm2. A homogeneous alignment was induced by assembling a nematic liquid crystal cell using a substrate plate covered with the photoirradiated films. The alignment direction of the cell was controlled by changing the electric vector of the actinic light. 相似文献