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排序方式: 共有271条查询结果,搜索用时 31 毫秒
21.
Noritaka Ohtani Yukihiko Inoue Hiroshi Mizuoka Kenya Itoh 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2589-2595
Dilute-solution viscosities of polystyrene-based cationic ionomers containing ammonio or phosphonio groups were measured in several solvents. In polar solvents with dielectric constant (εr) beyond 10, the ionomers showed a typical polyelectrolyte behavior, indicating that a large part of ionic groups were dissociated into ions. In nonpolar solvents with low εr, the reduced viscosity of the ionomers linearly decreased with a decreasing ionomer concentration. At low polymer concentrations, every ionomer gave a reduced viscosity lower than that of the corresponding chloromethylated polystyrene. With an increasing ion content, the intrinsic viscosity progressively decreased if the nonpolar solvents had a low acceptor number (AN), such as toluene or tetrahydrofran (THF). In the halogenated solvents with high AN value, such as chloroform, however, the intrinsic viscosity was hardly dependent on the ion content. This indicates that the intramolecular aggregation among the ionic groups is inhibited in the halogenated solvents due to a strong anion solvation. An addition of a protic solvent to a nonpolar solvent eliminates the aggregation between ionic groups and leads to polyelectrolyte behavior. © 1994 John Wiley & Sons, Inc. 相似文献
22.
Bunsho Ohtani Makoto Nishida Sei-ichi Nishimoto Tsutomu Kagiya 《Photochemistry and photobiology》1986,44(6):725-732
Photooxygenation reaction of an unsaturated fatty acid ester, methyl linoleate (methyl 9- cis. 12- cis -octadecadienoate, ML-H), sensitized by porphyrins and several types of dyes has been studied in aqueous emulsion and acetonitrile solution under air at 40°C. The oxygen (O2 ) uptake proceeded slowly in the absence of sensitizers upon irradiation of an aqueous emulsion and an acetonitrile solution of ML-H (20 m M ) at ℷex > 290 nm (11.4 and 6.1 μmol h-1 , respectively). The rate of O2 uptake was enhanced by a catalytic amount (0.1 m M ) of porphyrins and dyes; hematoporphyrin (HP), zinc tetrakis(N-methyl-4-pyridiniumyi)porphyrin (ZnTMPyP), methylene blue (MB), rose bengal (RB), acridine orange (AO), and acriflavine (AF). In both systems, the sensitized photooxidation of ML-H by O2 proceeded equimolarly to produce isomeric mixture of C9 and C13 hydroperoxides having the trans,cis and trans,trans conjugated diene configurations, independent of the types of the sensitizers used. The yield ratio of trans,trans/ trans,cis products in the MB-sensitized photooxygenation in acetonitrile and aqueous emulsion were almost equal (0.32 and 0.35. respectively). The sensitizing activity of the sensitizers, as measured by the quantum yield of O2 uptake, increased in the order: MB (≃ 0) < ZnTMPyP < RB < HP < AF < AO in the aqueous emulsion and AO < AF < HP < RB = MB in the acetonitrile solution. The order in homogeneous acetonitrile solution was interpreted by the sensitizing ability of the dyes to produce singlet oxygen, while that in heterogeneous aqueous emulsion was correlated to the lipophilicity of dyes as well as the singlet-oxygen-producing ability. 相似文献
23.
K. Hirose M. Ejima T. Fujibayashi Y. Fujii K. Futatsukawa O. Hashimoto T. Ishikawa S. Kameoka H. Kanda F. Kato S. Kinoshita T. Kinoshita T. Kon O. Konno K. Maeda A. Matsumura Y. Miura F. Miyahara H. Miyase T. Nakabayashi S.N. Nakamura H. Nomura K. Nonaka A. Ohtani Y. Okayasu M. Oyamada A. Sasaki H. Shimizu T. Takahashi T. Tamae H. Tamura T. Terasawa H. Tsubota K. Tsukada D. Uchida M. Ukai M. Wakamatsu T. Watanabe H. Yamauchi H. Yamazaki K. Yawata 《Physics letters. [Part B]》2009
24.
Adsorption and photochemical behaviors of the novel cationic xanthene derivative on the clay surface
Yuta Ohtani Yohei Ishida Yuka Ando Hiroshi Tachibana Tetsuya Shimada Shinsuke Takagi 《Tetrahedron letters》2014
Novel tetra-cationic xanthene derivative (Flu) was synthesized. Its adsorption and photochemical behaviors on the clay surface were investigated. Fluorescence quantum yield (?f) and fluorescence lifetime were 0.50 and 2.9 ns for Flu/clay complex. ?f of Flu was enough high (>0.1) even at high density conditions (0.080 molecules nm−2). It is supposed that the strong interaction between clay and Flu by the ‘Size-Matching Effect’ realizes the highly emissive clay complexes at high density adsorption condition by a suppression of a molecular aggregation, which tends to decrease the photochemical activity. 相似文献
25.
Structure and effective interionic potential of liquid palladium,platinum and zirconium 总被引:1,自引:0,他引:1
The structure of palladium, platinum and zirconium in the liquid state has been studied by X-ray diffraction near the melting point. In all the cases the structure factor looks similar to those of liquid metals such as copper and silver in contrast to mercury, tin and bismuth which show the small hump or the large asymmetry of the first peak maximum in the structure factor. The atomic radial distribution function was evaluated from the structure factor and the interatomic distance and coordination number of each liquid metal were also obtained. The effective interionic potential was derived from the structural data obtained in this work using the Born-Green equation and applied to the estimation of self-diffusion coefficient and viscosity coefficient in these liquid metals by the kinetic theory of fluids. 相似文献
26.
[structure: see text] Synthesis and fluorescence properties of pi-conjugated compounds having alternately an aromatic ring such as benzene, pyridine, and thiophene and an enediyne unit in the backbone are described. 相似文献
27.
The present investigation deals with the light-driven morphological changes in multilamella films of N-methyl-4-octadecyloxystilbazolium arylcarboxylates (C18OStz+X-) cast on glass slides. The results of XRD analysis show a photostimulated layer expansion and shrinkage of the stacked thin films along the c-axis under alternative illumination at >350 and 254 nm, respectively. It was revealed that such lamellar changes could be switched either way by a reversible transformation between the mono- and bilayer units in these stacked multilamella films. Moreover, such controlled structural adjustments in the alignment could be initiated by the photocyclodimerization of the stilbazolium moieties of the arylcarboxylate salts; i.e., a monolayer-to-bilayer transformation could be induced at a stage of only 10% cyclodimer formation. The photoinduced patterning on the surface of the films was also analyzed by SEM and fluorescence microscopic investigations. 相似文献
28.
A. Takizawa T. Kinoshita A. Ohtani Y. Tsujita 《Journal of polymer science. Part A, Polymer chemistry》1986,24(4):665-672
The effects of the oxidative reaction on the ionic permeabilities through polypeptide membranes containing thiol groups in the side chains were investigated. Membranes were derived from poly(glutamyl-cysteine) (PGC) containing 12% (in mol %) of ? SH groups in the side chains, and from poly(L-cysteine) (PlCys) containing 26% of thiol groups in the side chains, respectively. On the basis of the polarographic analysis, it can be estimated that more than 80% of ? SH groups in the membranes could be oxidized by using 10 mM solution of iodine. The membrane potentials across the PGC membrane were increased by the iodine oxidation, indicating that ? SH groups of PGC were converted to highly dissociable groups, i.e., sulfonic acid derivatives. The decrease in the ionic permeabilities through the PGC membrane by the oxidation, therefore, was attributed to the decrease in ionic solubility into the membrane owing to the increase in fixed charge density of the membrane (Donnan exclusion effect). On the other hand, no influence of the oxidation on the membrane potentials of the PCys membrane suggests the possibility of oxidative S-S cross linking in the membrane. The oxidation-induced permeability decrease of the PCys membrane could be explained in terms of the decrease in ionic diffusibility associated with the formation of the side chain cross linkings between ? SH groups in the membrane. 相似文献
29.
Masaki Ando Sakiyo ImadzuShinya Kitagawa Hajime Ohtani 《Journal of chromatography. A》2010,1217(32):5298-5301
A particulate formation-laser scattering detector (PFLSD) was developed and used for evaluating the crystallization efficiency of inorganic polyphosphates (PPs) that reacted with either magnesium or calcium cations. As the solutions for reactive crystallization, 0.5 M ammonium buffer (pH 9.6) containing either 0.15 M MgCl2 or 0.15 M CaCl2 (MAP: magnesium ammonium phosphate and HAP: hydroxyapatite solution) were used. In the case of mono- and diphosphate (P1 and P2), the significant dependences of the particulate formation efficiency on various types of both P1/P2 and MAP/HAP reaction solutions were observed with the direct sample injection mode. The PFLSD was hyphenated with the anion-exchange chromatography and the dependence of the particulate formation efficiency on the polymerization degree (np) of PP oligomers, separated chromatographically, was evaluated sequentially. The significant suppression of the particulate formation for PP oligomers was clearly confirmed, i.e., the MAP and HAP reaction solutions did not produce the particulates of the PP oligomers having an np value of more than 3 and 5, respectively. As the overall tendency, the particulate formation efficiency in the case of the HAP solution was superior to that in the case of the MAP solution. 相似文献
30.