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61.
Bungo Ochiai Tomomi Nagasawa Yasuhiro Asano Daisuke Nagai Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2820-2826
Thermal behaviors were monitored by infrared thermographic analysis in the copolymerization of a spiroorthoester and a bifunctional oxetane with thermally latent initiators [benzyl tetrahydrothiophenium hexafluoroantimonate (BTHT) and benzyl 4‐hydroxyphenyl methyl sulfonium hexafluoroantimonate (BPMS)]. The copolymerization with BPMS increased the temperature during the copolymerization more than that with BTHT, whereas the exothermicities were lowered with the increase in the initial feed ratio of the spiroorthocarbonate monomer. The high exothermicity in the copolymerization with BPMS is ascribable to the faster propagation of the oxetane monomer with a high heat of polymerization, and this is supported by model reactions and computational calculation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2820–2826, 2007 相似文献
62.
Tomomi Nagasawa Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(8):1388-1393
Infrared (IR) thermography was employed to monitor temperature changes during the copolymerization of a spiroorthoester monomer with an oxetane monomer initiated with a benzyl sulfonium salt. The temperature changes in the polymerizations decreased with the increase of the initial feed ratios of the spiroorthocarbonate monomer. For instance, the temperature in the copolymerization of the equimolar mixture of both of the monomers increased only ~1 °C, whereas that in the homopolymerization of the oxetane monomer increased more than 20 °C. This result indicates that the copolymerization employing spiroorthocarbonate monomers effectively suppress temperature increase, which are responsible to shrinkage during cooling. The suppression of polymerization shrinkage by spiroorthocarbonate was also confirmed by density measurement of the polymers using a gas pycnometer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1388–1393, 2007. 相似文献
63.
Sachiko Ishida Takashi Ono Tomomi Yokota 《Mathematical Methods in the Applied Sciences》2013,36(7):745-760
This paper deals with the quasilinear ‘degenerate’ Keller–Segel system of parabolic–parabolic type under the super‐critical condition. In the ‘non‐degenerate’ case, Winkler (Math. Methods Appl. Sci. 2010; 33:12–24) constructed the initial data such that the solution blows up in either finite or infinite time. However, the blow‐up under the super‐critical condition is left as an open question in the ‘degenerate’ case. In this paper, we try to give an answer to the question under assuming the existence of local solutions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
64.
We study a polytope which arises from a mixed integer programming formulation of the quadratic semi-assignment problem. We introduce an isomorphic projection and transform the polytope to a tractable full-dimensional polytope. As a result, some basic polyhedral properties, such as the dimension, the affine hull, and the trivial facets, are obtained. Further, we present valid inequalities called cut- and clique-inequalities and give complete characterizations for them to be facet-defining. We also discuss a simultaneous lifting of the clique-type facets. Finally, we show an application of the quadratic semi-assignment problem to hub location problems with some computational experiences. 相似文献
65.
Kouken Kaniwa Tomomi Sonoda Masahiko Hayashi Masami Ishibashi 《Tetrahedron letters》2006,47(26):4351-4354
Trichiol (1) and 3-epitrichiol acetate (2), two new sterols, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures elucidated by spectral data. Trichiol (1) and 3-epitrichiol acetate (2) possess an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system. Trichiol (1) was cytotoxic against HeLa cells, while compound 2 proved to exhibit reversal effect against TNF-related apoptosis inducing ligand (TRAIL)-resistant Jurkat cell lines. 相似文献
66.
Onuma K Watanabe A Kanzaki N Kubota T 《The journal of physical chemistry. B》2006,110(49):24876-24883
The intermolecular interaction and association dynamics of the Ynd1p protein were investigated using dynamic and time-resolved static light scattering measurements. The mutual diffusion coefficients of wild- and mutant-type (a single amino acid substitution) Ynd1p monomer were measured in 50 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer with 5 mM MnCl2 and 7.5% (v/v) ethylene glycol. Both translational diffusion coefficients at a zero protein concentration were (40.3 +/- 0.2) x 10(-12) m2/s at 20 degrees C and a pH of 7.0, so the hydrodynamic radius of the monomers was 4.1 +/- 0.1 nm. The measured intermolecular interaction between monomers, however, showed that the mutant-type Ynd1p had a stronger attractive force. Time-resolved static light scattering measurements showed that the association of mutant-type Ynd1p yielded a larger number of aggregates than that of wild-type Ynd1p. The time dependence of aggregate gyration radius differed between the two types. Fractal dimension analysis using scattering intensity data suggested that the inner structure of the aggregates changed from loose to rigid with time. Although this phenomenon is common for wild and mutant types, the differences in the number of aggregates yielded in the initial stages and in the intermolecular interaction affected the quality of the final grown crystals. That is, single crystals of Ynd1p grew in the mutant-type protein solution and polycrystals of Ynd1p grew in the wild-type protein solution. 相似文献
67.
Eisuke Kaji Teruaki Komori Masaki Yokoyama Tomomi Kato Takashi Nishino Tatsuya Shirahata 《Tetrahedron》2010,66(23):4089-4100
An efficient convergent synthetic method has been developed for preparation of various stereoisomers and derivatives of fattiviracins via a common lactide. The synthetic route comprises seco acids prepared by the β-selective glycosylation of chiral 3-hydroxy-4-pentanoate obtained by enzymatic kinetic resolution. The regioselective protection of four individual hydroxy groups was achieved via the 4,6-O-benzylidenation of the glucose moiety from its TMS ethers. The dimeric cyclization of the seco acids under control of reaction concentration afforded the desired lactide without using KH. Our convergent synthetic method was successfully applied to direct installation of side chains to the lactide by cross metathesis to synthesize fattiviracin derivatives. We achieved improvements to the reported method with respect to: (1) synthesis of a convergent synthetic intermediate; (2) stereoselectivity in glycosylation; and (3) establishment of a low cost route suitable for large scale synthesis. 相似文献
68.
Contrary to the usually accepted phenomena, an optically heterogeneous 1:1 diastereomixture of DS and LS and a racemate of LS and DR obtained, respectively, from a racemic myo-inositol derivative and (S)- and racemic O-acetylmandelic acid formed stronger organogels, especially with aromatic fluids, than those formed from homochiral isomers, DS and LS. One of the plausible reasons for the formation of the stronger diastereomeric gel is shown to be the complementary interaction of two diastereomers. 相似文献
69.
Ito S Yokoyama R Okujima T Terazono T Kubo T Tajiri A Watanabe M Morita N 《Organic & biomolecular chemistry》2003,1(11):1947-1952
2-Azulenyl trifluoromethanesulfonate was prepared by the reaction of 2-hydroxyazulene with trifluoromethanesulfonic anhydride in the presence of triethylamine as a base. Under the use of pyridine, 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate further reacted with 2-azulenyl trifluoromethanesulfonate to give 1-(1-trifluoromethanesulfonyl-1,4-dihydropyridin-4-yl)azulenyl trifluoromethanesulfonate. Moreover, we found that azulenes also reacted with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate to give 4-(1-azulenyl)-1,4-dihydropyridine derivatives and 6-(1-azulenyl)-1-trifluoromethanesulfonyl-1-aza-hexa-1,3,5-triene depending on the reaction conditions. 2-Azulenyl trifluoromethanesulfonate was converted finally into the parent azulene in excellent yield by palladium-catalyzed reduction using formic acid as a reducing reagent. 相似文献
70.
We developed a new analysis method for the nine N-methyl carbamate pesticides in fruits and vegetables using ESI LC/MS/MS with direct sample injection into a short column. After extraction of the pesticides with ethyl acetate from sample, the extract is evaporated to dryness and redissolved in ultra pure water before injection into LC/MS/MS. The method needs no cleanup steps. The average recoveries from fruits and vegetables fortified at the level of 0.01 μg/g ranged from 56.0 to 119.1% with the coefficients of variation ranging from 0.2 to 7.6% for intra-day (n = 5 × 3 days) and from 0.8 to 18.4% for inter-day (n = 15). At the fortified level of 0.5 μg/g, the recoveries ranged from 67.7 to 119.3% with the coefficients of variation ranging from 0.5 to 7.8% for intra-day (n = 5 × 3 days) and from 0.9 to 14.8% for inter-day (n = 15). The method is considered to be satisfactory for the monitoring of the carbamate pesticide residues in fruits and vegetables, suggesting that the present method is applicable to other pesticide residues in foods. 相似文献