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151.
Hideyuki Uematsu Yuji Aoki Masataka Sugimoto Takashi Taniguchi Kiyohito Koyama 《Rheologica Acta》2008,47(2):237-242
We investigated the dynamic viscoelasticity and elongational viscosity of polypropylene (PP) containing 0.5 wt% of 1,3:2,4-bis-O-(p-methylbenzylidene)-d-sorbitol (PDTS). The PP/PDTS system exhibited a sol–gel transition (T
gel) at 193 °C. The critical exponent n was nearly equal to 2/3, in agreement with the value predicted by a percolation theory. This critical gel is due to a three-dimensional
network structure of PDTS crystals. The elongational viscosity behavior of neat PP followed the linear viscosity growth function
3η
+
(t), where η
+
(t) is the shear stress growth function in the linear viscoelastic region. The elongational viscosity of the PP/PDTS system
also followed the 3η
+
(t) above T
gel but did not follow the 3η
+
(t) and exhibited strong strain-softening behavior below T
gel. This strain softening can be attributed to breakage of the network structure of PDTS with a critical stress (σ
c) of about 104 Pa. 相似文献
152.
Nobuhiro Taneichi Yuri Sekiya Hideyuki Imai 《Annals of the Institute of Statistical Mathematics》2003,55(4):831-848
We consider multinomial goodness-of-fit tests for a specified simple hypothesis under the assumption of sparseness. It is
shown that the asymptotic normality of the PearsonX
2 statistic (X
k
2
) and the log-likelihood ratio statistic (G
k
2
) assuming sparseness. In this paper, we improve the asymptotic normality ofX
k
2
andG
k
2
statistics based on two kinds of normalizing transformation. The performance of the transformed statistics is numerically
investigated. 相似文献
153.
154.
155.
Hideyuki Kawahara Yoshihiro Ueno Nanae Abe Shiho Kishino Kazuhiro Ema Masahiro Rikukawa Yuko Tabuchi Naoya Ogata 《Optical Review》1997,4(1):188-190
We measured the third-order optical nonlinearity of regioregular head-to-tail coupled poly (3-hexylthiophene) (HT-PHT) and regiorandom poly (3-hexylthiophene) (R-PHT) around exciton resonance using degenerate four wave mixing. The observed value of ∣χ(3)∣ at the exciton resonance peak of HT-PHT is in the order of 10-9 esu which is approximately three-fold larger than that of R-PHT. We observed for the first time the enhancement in optical nonlinearity that occurs through the control of regularity of the polymeric structure. Response time of the nonlinearity was also measured using the transient grating method. The decay time of the transient grating in R-PHT and HT-PHT was less than 2 ps. 相似文献
156.
Mitsuko Masutani Tadashige Nozaki Hiroki Sasaki Tesshi Yamada Takashi Kohno Kimiko Shimizu Masahiro Gotoh Masahiko Shiraishi Jun Yokota Setsuo Hirohashi Hitoshi Nakagama Takashi Sugimura 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(2):114
Poly(ADP-ribose) polymerase-1 (Parp-1) is involved in DNA repair and cell-death induction after DNA damage. Parp-1−/− mice show higher susceptibility to the carcinogenic effects of nitrosamine and azoxymethane. To elucidate the role of alterations of the PARP-1 gene in human carcinogenesis, we examined the expression level of PARP-1 gene in various human tumor cell lines. The presence of gross rearrangement of PARP-1 gene in these cell lines was also examined by Southern blot hybridization analysis. The expression levels of PARP-1 gene in several cell lines, including T-cell leukemia cell lines (Molt-4 and CCRF-CEM), colon cancer cell line (WiDr), and gastric cancer cell lines (KATOIII, OKAJIMA, and MKN45) was substantially lower than in other cancer cell lines. Among the 85 analyzed cell lines, structural alteration of PARP-1 gene was detected in a gastric cancer cell line, MKN28. A low level of PARP-1 expression in human cancer could potentially influence cancer cell growth, differentiation and cancer development by affecting genomic instability, as well as the response of tumors to chemo- and radiotherapy. 相似文献
157.
Takaaki Sugimura Yuji Minoura 《Journal of polymer science. Part A, Polymer chemistry》1966,4(11):2735-2746
The effect of diphenyl thiourea (DPTU) on the radical polymerization of methyl methacrylate (MMA) has been studied in benzene solution at 50°C. with the use of cumene hydroperoxide (CHP), p-menthane hydroperoxide (PMHP), tert-butyl perbenzoate (tBPBz), di-tert-butyl peroxide (DBP), and dicumyl peroxide (DCP) as initiators. In the CHP-initiated polymerization, the rate of polymerization increased appreciably on addition of DPTU with a linear dependence on the square root of DPTU concentration up to a maximum which was observed when the ratio of the concentration of CHP to DPTU was 2.5. Then the rate decreased gradually with increasing DPTU concentration in the range greater than the above ratio. It was found from kinetic studied that the overall polymerization rate Rp was expressed by the equation: Rp = K[peroxide]1/2 [DPTU]1/2[MMA], where K is the rate constant, α = 1.2 for CHP and α = 1.0 for tBPBz. It was thought that the acceleration effect observed was due to a redox reaction caused by the interaction of a peroxide–monomer and/or a peroxide–solvent complex with DPTU, and the decrease in the polymerization rate which was observed over a certain concentration of DPTU was due to the action of the oxidized product of DPTU as a transfer agent. The effect of substituents was studied by using para and meta-substituted DPTU. It was found that the polymerization rate increased as electron-donating substituents are added to the benzene ring of DPTU with considerable dependence on Hammett's equation (p = ?0.36). The acceleration effect is also observed for PMPH-and tBPBz-initiated polymerizations, whereas the DCP- and DBP-initiated systems show no effects on the polymerization rate. 相似文献
158.
A general expression of the perfect matching number for thel x m x n cubic lattice was conjectured and examined for infinitely large systems. The asymptotic value of the square of the perfect matching number was calculated by numerical integration. The present treatment will give a key to obtain the true analytic solution of the perfect matching numbers for the 3-dimensional lattices. 相似文献
159.
A sensitive and selective column adsorption method is proposed for the off-line preconcentration and determination of phthalic acid esters (PAEs), namely benzyl-butyl phthalate (BBP), di-n-butyl phthalate (DBP) and di-cyclohexyl phthalate (DCHP). The PAEs was preconcentrated on Saccharomyces cerevisiae immobilized on silica gel and then determined by high performance liquid chromatography (HPLC). Several parameters on the recovery of the analytes were investigated. Recoveries of BBP, DBP and DCHP were 100±2, 98±2 and 98±3%, respectively, at 95% confidence level under optimum conditions. The detection limits (3S/N) of BBP, DBP and DCHP were 3.2, 6.3 and 3.1 μg l−1, respectively. The capacity of the adsorbent was also examined and found to be 1.4 mg g−1 for BBP and DBP, and 3.6 mg g−1 for DCHP. S. cerevisiae immobilized on silica gel is suitable for repeated use without decreasing recovery up to about 25 adsorption-elution cycles. The proposed method was successfully applied to the determination of PAEs in river water with high precision and accuracy. 相似文献
160.
Takashi Sugimura 《Catalysis Surveys from Japan》1999,3(1):37-42
Tartaric acidmodified Raney nickel (TAMRNi) is an enantiodifferentiating catalyst for hydrogenation of ketones. The stereochemical models explaining the enantiodifferentiation of ketoester and 2alkanone were unified as an extended stereochemical model by the experimental supports. Based on this new model, a working hypothesis to improve the enantiomeric excess (ee) of the ketoester/TAMRNi system was developed, and the ee was improved to 96%. By further fine tuning of this system, almost perfect enantiodifferentiation resulting in over 98% ee was achieved. 相似文献