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排序方式: 共有199条查询结果,搜索用时 218 毫秒
91.
Aihara Y Sonai A Hattori M Hayamizu K 《The journal of physical chemistry. B》2006,110(49):24999-25006
To understand the behaviors of phosphoric acids in fuel cells, the ion conduction mechanisms of phosphoric acids in condensed states without free water and in a monomer state with water were studied by measuring the ionic conductivity (sigma) using AC impedance, thermal properties, and self-diffusion coefficients (D) and spin-lattice relaxation times (T1) with multinuclear NMR. The self-diffusion coefficient of the protons (H+ or H3O+), H2O, and H located around the phosphate were always larger than the diffusion coefficients of the phosphates and the disparity increased with increasing phosphate concentration. The diffusion coefficients of the samples containing D2O paralleled those in the protonated samples. Since the 1H NMR T1 values exhibited a minimum with temperature, it was possible to determine the correlation times and they were found to be of nanosecond order for a distance of nanometer order for a flip. The agreement of the ionic conductivities measured directly and those calculated from the diffusion coefficients indicates that the ion conduction obeys the Nernst-Einstein equation in the condensed phosphoric acids. The proton diffusion plays a dominant role in the ion conduction, especially in the condensed phosphoric acids. 相似文献
92.
Atsuo Iida Yumiko Takahashi Yoichi Takanishi Michi Nakata Ken Ishikawa Hideo Takezoe 《Liquid crystals》2005,32(6):717-726
The local layer structure of surface stabilized electroclinic liquid crystals has been analysed by time-resolved synchrotron X-ray microdiffraction. At a low applied electric field, the initial bookshelf structure starts to respond above a threshold voltage. With a low to medium applied field of triangular form, the layer structure transforms reversibly between the bookshelf (low field) and the compound chevron (high field), in which the vertical and horizontal chevrons alternate along the layer. When the horizontal chevron component appears, a stripe texture can be seen in an optical micrograph. With increasing field, the horizontal chevron becomes a dominant structure while the vertical chevron still remains. The layer spacing changes in correlation with the chevron angle during the field application. At high field, surface molecules partly rearrange, resulting in alignment deterioration at the interface. The layer response time for an a.c. square wave field is of the order of a few µs to ten µs, which is close to the optical response. The appearance of the compound chevron is discussed in conjunction with the anchoring effect. 相似文献
93.
Atsuo Fukuda Ichiro Kawamura Y. Suzuki T. Hagiwara I. Kawamura N. Okamura T. Kitazume M. Kakimoto Y. Imai Y. Ouchi H. Takezoe A. Fukuda 《Liquid crystals》2006,33(11):1339-1349
A Commentary on the paper “New fluorine-containing ferroelectric liquid crystal compounds showing tristable switching„, by Y. Suzuki, T. Hagiwara, I. Kawamura, N. Okamura, T. Kitazume, M. Kakimoto, Y. Imai, Y. Ouchi, H. Takezoe and A. Fukuda. First published in Liquid Crystals, 6, 167-174 (1989). 相似文献
94.
AgOAc/ThioClickFerrophos complex-catalyzed 1,3-dipolar cycloaddition of glycine imino ester, the precursor of azomethine ylide, with aryl- and alkylidene malonates afforded the corresponding exo-cycloadducts, that is, proline ester derivatives in high yields with high enantiomeric excess (up to 99% ee). The reactions proceeded smoothly under base-free conditions demonstrating the bifunctional catalysis of the silver complex. 相似文献
95.
Toshihiro Kobayashi Yuriko Matsumura Toshihiko Ozawa Hiroyuki Yanai Atsuo Iwasawa Toshiaki Kamachi Kouichi Fujiwara Noriaki Tanaka Masahiro Kohno 《Analytical and bioanalytical chemistry》2014,406(5):1365-1376
To identify blood markers for early stages of chronic kidney disease (CKD), blood samples were collected from rats with adenine-induced CKD over 28 days. Plasma samples were subjected to metabolomic profiling by liquid chromatography-mass spectrometry, followed by multivariate analyses. In addition to already-identified uremic toxins, we found that plasma concentrations of N6-succinyl adenosine, lysophosphatidylethanolamine 20:4, and glycocholic acid were altered, and that these changes during early CKD were more sensitive markers than creatinine concentration, a universal indicator of renal dysfunction. Moreover, the increase in plasma indoxyl sulfate concentration occurred earlier than increases in phenyl sulfate and p-cresol sulfate. These novel metabolites may serve as biomarkers in identifying early stage CKD. 相似文献
96.
Abstract Using Parodi's relation, all of the Leslie viscosity coefficients, except μ1, together with the Frank elastic constants have been measured successfully by the photon correlation spectroscopy of Rayleigh scattered light. The values so determined are in good agreement with those previously determined from shear flow experiments by Chmielewski and by Skarp et al. The polar angle dependence of mode 1 spectral width is proposed as a novel method for the measurement of μ1 and for the experimental confirmation of Parodi's relation. 相似文献
97.
Masahiro Murayama Noriyuki Sonoyama Atsuo Yamada Ryoji Kanno 《Solid State Ionics》2004,170(3-4):173-180
A new lithium ionic conductor of the thio-LISICON (LIthium SuperIonic CONductor) family was found in the binary Li2S–P2S5 system; the new solid solution with the composition range 0.0≤x≤0.27 in Li3+5xP1−xS4 was synthesized at 700 °C and characterized by X-ray diffraction measurements. Its electrical and electrochemical properties were studied by ac impedance and cyclic voltammetry measurements, respectively. The solid solution member at x=0.065 in Li3+5xP1−xS4 showed the highest conductivity value of 1.5×10−4 S cm−1 at 27 °C with negligible electronic conductivity and the activation energy of 22 kJ mol−1 which is characteristic of high ionic conduction state. The extra lithium ions in Li3PS4 created by partial substitution of P5+ for Li+ led to the large increase in ionic conductivity. In the solid solution range examined, the minimum conductivity was obtained for the compositions, Li3PS4 (x=0.0 in Li3+5xP1−xS4) and Li4P0.8S4 (x=0.2 in Li3+5xP1−xS4); this conductivity behavior is similar to other thio-LISICON family with the general formula, LixM1−yMy′S4 (M=Si, Ge, and M′=P, Al, Zn, Ga, Sb). Conduction mechanism and the material design concepts are discussed based on the conduction behavior and the structure considerations. 相似文献
98.
Takashi Moriyama Yoichi Takanishi Ken Ishikawa Hideo Takezoe Atsuo Fukuda 《Liquid crystals》1995,18(4):639-643
We have observed the diffusion constants of a dye in several liquid crystals by forced Rayleigh scattering. In a liquid crystal which has a standard phase sequence of N-SA-SC, the diffusion anisotropy changes at the N-SA phase transition and increases with decreasing temperature in SA and SC phases. The diffusion constants exhibit a rather smooth decrease with decreasing temperature except an anomaly at the SA-Sc phase transition. In a liquid crystal which has the antiferroelectric SCA phase, however, the diffusion constants show discontinuous increase and decrease at the SA-Sc and the Sc-ScA phase transition temperatures, respectively: the diffusion constant in SC is larger than that in the higher temperature SA phase. Anomalous signal increase and profile were observed at the phase transition temperatures, and were ascribed to the complementary transient grating due to the coexistence of two phases. 相似文献
99.
Different modes of cyclization in zoanthamine alkaloid system, bisaminal versus spiroketal formation
Nakajima T Yamashita D Suzuki K Nakazaki A Suzuki T Kobayashi S 《Organic letters》2011,13(12):2980-2983
Bisaminal cyclization in the zoanthamine alkaloid system was strongly affected by the stereochemistry of the C4 methyl. While cyclization of the (4S)-methyl precursor gave only a bisaminal compound, cyclization of the (4R)-methyl isomer produced both spiroketal and bisaminal products. 相似文献
100.
Chiral Schiff base complexes containing azo-groups, bis(N-R-1-naphtylethyl-4-phenyldiazenylsalicydenaminato) nickel(II), copper(II), and zinc(II) complexes affording a distorted square planar trans-[MN2O2] coordination geometry were prepared newly. Organic/inorganic hybrid materials in polymethylmethacrylate (PMMA) cast films of them (a containing type) or the analogous chiral Schiff base complexes, bis(N-R-1-phenylethyl-3,5-dichlorosalicydenaminato) nickel(II), copper(II), and zinc(II), and azobenzene (AZ) (a separated type) were assembled for comparison of polarized UV light induced molecular arrangement caused by Weigert effect. Investigation of parameters for optical anisotropy of metal complexes as well as AZ suggested that the degree of increasing optical anisotropy of the containing type is higher than that of the separated type based on π-π∗ (of which characteristic band appeared around 380 nm), n-π∗, and d-d bands of polarized absorption electronic spectra. Rigid nickel(II) or zinc(II) complexes are easy to increase optical anisotropy than flexible copper(II) complexes for both types. 相似文献