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491.
Hisanori Sugiura Yoshiaki Saklrai Yoshihide Masuda Hitoshi Takeda Shigekazu Kusabayashi Shunsuke Takenaka 《Liquid crystals》1991,9(3):441-450
The thermal properties of 4-octyloxyphenyl 4-(4-R-3-nitrobenzoyloxy) benzo-ates (1) and 4-(4-octyloxybenzoyloxy)phenyl 4-R-3-nitrobenzoates (2) have been examined, where R = hydrogen, halogens, alkyl and alkoxy groups. The derivatives of compound 1 incorporating hydrogen, halogens, methoxy and nitro groups show a smectic A phase having a bilayer arrangement, and the others with a long alkoxy group show the SA phase with the monolayer arrangement. The derivatives of compound 2 incorporating halogens, and the nitro group show the SA phase with the monolayer arrangement. The alkoxy derivatives show a smectic C phase as well as the nematic phase. The nitro group at the lateral position tends to increase the ratio of the SA-N transition temperature to the N-I. The effect of the nitro group on the smectic properties has been discussed in terms of the structural and electrostatic nature of the nitro group. 相似文献
492.
In this paper, we study subgroups of self-homotopy equivalences associated to generalized homology theories. We generalize
Dror-Zabrodsky’s nilpotency theorem on the group of self-homotopy equivalences.
Dedicated to Professor Akio Hattori on his sixtieth birthday
The first-named author was partially supported by Grant-in-Aid for the Science Research of the Ministry of Education, 02740012. 相似文献
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New liquid crystalline (LC) homo- and copolymethacrylates having a carbonate linkage between a benzylideneaniline mesogen and ethylene chain in the side chain were prepared by free radical polymerization of methacrylate derivatives comprising 4-cyano- and/or 4-methoxybenzylide-neaniline units using AIBN as an initiator. The structures of the polymers were characterized by FTIR, 1HNMR, and elemental analyses. The LC properties were evaluated by differential scanning calorimetry (DSC), polarizing microscopic observation of textures and X-ray diffraction. These measurements showed that all the homo- and copolymers form nematic phases. The isotropization temperatures on composition exhibited a negative deviation from a linear relationship between them predicted by the Schroeder-Van Laar equation. This phenomenon might be caused mainly by an unusual geometry arising from a smaller bond angle in the carbonate linkage. 相似文献
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496.
Infrared spectra of a thiourea adduct of monobromocyclohexane were measured in the region 4000 cm?1 to 30 cm?1. The axial conformer was found to be predominant in the host lattice. Infrared spectra of thiourea adducts of mixtures of monochlorocyclohexane and monobromocyclohexane were also measured and the spectra interpreted. 相似文献
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500.
The surface of mesoporous silicate, FSM-16, was investigated by infrared spectroscopy (IR) using methane and carbon monoxide as molecular probe. The appearance of 1-peak of adsorbed CH4 indicated the presence of electric field (1.4 × 105 esu) which is attributed to a weakly polarized free silanol site (site-1). The site was located at the void of oxygen framework in FSM-16 pore wall. In addition, the presence of site-2 without any electric field was found by IR spectra of adsorbed CO. The latter site was assigned to a interacted silanol groups and/or a Si–O–Si site. 相似文献