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91.
Prof. Dr. Yoshinobu Isono Toshihiro Kamohara Atsushi Takano Toshio Kase 《Rheologica Acta》1997,36(3):245-251
Simultaneous measurements of stress relaxation and differential dynamic modulus were made at 268 K over a time scale of 10 to 1045 s for nearly monodisperse polybutadiene (M
w
=2.2x105, 1,2-structure 70%, M
e
=3600) and also one having coarse cross-linking (M
c
=29000). Static shear strain ranged from 0.1 to 2.0. In a long-time region (t>
k
), the relaxation modulus G (; t) could be expressed by the product G (0; t) h (y). The observed h() agreed well with the Doi-Edwards theory without use of IA approximation. Both the cured and uncured samples showed initial drop of the differential storage modulus G (), ; t) followed by gradual recovery, but did not attain the value before shearing G (, ; t) for the uncured sample showed smaller values than that for the cured one in the whole measured time scale at the higher strain, confirming the two origins of nonlinear viscoelasticity of well entangled polymer; induced chain anisotropy and induced decrement in entanglement density. G (, ; t) curves for the cured sample agreed well with the BKZ predictions. But the curves for the uncured sample agreed well with the BKZ prediction only at the time scale of t<
k
. BKZ prediction showed significant upward deviations at t>
k
. Such the differences are discussed in terms of the two origins.Dedicated to Prof. John D. Ferry on the occasion of his 85th birthday. 相似文献
92.
Two new cycloartane glycosides, named aquilegiosides K and L, have been isolated from the dried underground parts of Aquilegia vulgaris. Their structures were determined by two dimensional (2D) NMR spectroscopic analysis and chemical evidence. 相似文献
93.
We investigate the photoluminescence (PL) properties of silver/porous-silicon (Ag/PSi) nanocomposites prepared by metal-assisted etching in solution, on the basis of steady-state and time-resolved PL spectroscopy measurements. The PL intensity and peak position are strongly dependent on the concentration. Time-resolved PL measurements reveal that the nonradiative rate decreases with an increase in the concentration for the Ag/PSi nanocomposites. It is found from x-ray photoelectron spectroscopy measurements that the decrease in the nonradiative rate is caused by the formation of layers on the PSi surfaces. Further, the number of light-emitting Si nanocrystals in the nanocomposites, which is estimated from the PL decay rate and PL intensity, increases with the concentration. From the wavelength dependence of the PL decay rate, it is found that the nonradiative rate is considerably dispersive, i.e., the shorter the wavelength, the higher the nonradiative rate. 相似文献
94.
Two novel aromatic glycosides were obtained from Puerariae Radix and their chemical structures were characterized. 相似文献
95.
Akemi Umeyama Chihiro Ohta Yukari Shino Minori Okada Yukari Nakamura Tatsuya Hamagaki Hiroshi Imagawa Masami Tanaka Aki Ishiyama Masato Iwatsuki Kazuhiko Otoguro Satoshi Ōmura Toshihiro Hashimoto 《Tetrahedron》2014
During the search for new antitrypanosomal drug leads, three new antitrypanosomal compounds, hexatenuins A–C (1–3), were isolated from the fruiting body of Hexagonia tenuis. 1 and 3 possessed an unusual malonate half-ester functional group at C-3 position, and 1 and 2 had a spirostructure in the side-chain. Their structures were elucidated using MS analyses, extensive 2D-heteronuclear NMR data interpretation. Compounds 1–3 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei with IC50 values of 0.57, 8.60 and 5.62 μg/ml, respectively. 相似文献
96.
Masahiro Manabe Toshihiro Ochi Hideo Kawamura Hajime Katsu-ura Masaki Shiomi Mandeep Singh Bakshi 《Colloid and polymer science》2005,283(7):738-746
The partial molar volumes (Va) of 1-alkanols (carbon number, m=5, 6, 7) in - and -cyclodextrin (CD) solutions at 5.00 mmol kg–1 have been determined as a function of alkanol concentration (Ca) between 293.2 and 308.2 K by using a dilatometer. It has been observed that with an increase in Ca, Va increased in -CD solution but decreased in -CD solution, asymptotically to a value of Va in CD-free water. The dependence of Va on Ca provided the binding constant (K) of 1:1 complex, the volume change in complex formation, and the partial molar volume of complex itself. The complex formation mechanism has been discussed on the basis of these values and their carbon number dependences in the respect of geometric behavior, hydrophobic interaction, and van der Waals interaction. It is concluded that the CD cavity in water is not rigid but flexible for fitting in nicely with guest molecule. 相似文献
97.
Glass bead/x‐ray fluorescence spectrometry of the sludge incineration ashes generated in sewage processing was developed for the determination of ten major components (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3) and five minor elements (Zn, Cu, Cr, As, Pb). Sewage sludge ashes consisted of rock‐forming minerals and phosphate crystals that had been used for phosphorus removal. Ash samples were melted and molded with lithium tetraborate to 35 mm diameter glass disks in a Pt–Au crucible. Analytical results of ten major components and five minor elements agreed well with the recommended values of a phosphate rock standard reference material (NIST SRM 694). Elemental compositions of sewage sludge ash from seven sewage‐processing plants in Japan were determined using this method. Concentrations of Fe2O3, SiO2, and CaO, along with loss of ignition in sewage sludge ash mutually differed among the sewage‐processing plant products. Seasonal variations in concentrations of ten major components and five minor components of ash samples produced from October 2001 to September 2002 were determined using the proposed method. Concentrations of SiO2increased with the inflow of gravel by rainfall, thereby decreasing concentrations of P2O5 originating from excreta and microorganisms. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
98.
99.
Toshihiro Yamaguchi 《Czechoslovak Mathematical Journal》2005,55(4):997-1001
We give an example of a space X with the property that every orientable fibration with the fiber X is rationally totally non-cohomologous to zero, while there exists a nontrivial derivation of the rational cohomology of
X of negative degree. 相似文献
100.
The techniques of chemical ligation have attracted great attention as an alternative to enzymatic joining of DNA ends. Here we introduce the photoligation of anthracene-modified ODN conjugates through anthracene cyclodimer formation. The effect of the positions and the kinds of single base mismatch on the template was evaluated using eight templates with one-base displacements. We found out that the yield of the ligation was affected by mispairing in a position-dependent manner. Such results would be attributed to the disruption of the local structure at the ligation site. 相似文献