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32.
Summary Two commercially available liquid crystals, 4-cyano-4′-n-pentyl-1,1′-bipheny and 4-cyano-4′-n-pentoxy-1,1′-bipheny, are bonded to a silica hydride surface via hydrosilation in the presence of a free radical iniator,
t-butyl peroxide. Elemental analysis, diffuse reflectance Fourier trans-form infrared spectroscopy, and13C and29Si CP-MAS NMR spectroscopy are used to confirm the success of the bonding reaction. The13C CP-MAS spectra suggest a difference in the bonded phase morphology of the two materials. Static hydrolytic stability tests
indicate these materials do not degrade significantly in both acidic and basic solutions. Chromatographic tests confirm that
these two bonded phase behave differently with respect to their retention of PAHs, alkyl-substituted benzenes and benzodiazepines. 相似文献
33.
Synthesis of trisaccharide repeating unit, -->3)-alpha-D-Rhap-(1-->2)-alpha-D-Manp3CMe-(1-->3)-alpha-L-Rha p-(1-->, and its dimeric hexa- and trimeric nonasaccharide subunits of the atypical O-antigen polysaccharide of the lipopolysaccharide from Danish H. pylori strains D1, D3, and D6 has been accomplished. Successful synthesis of the hexasaccharide and the nonasaccharide was possible by dimerization and trimerization of the suitably protected trisaccharide repeating unit, in which three monosaccharide moieties were arranged in a proper order by placing the sterically demanding 3-C-methyl-D-mannose moiety in between D- and L-rhamnoses. Key steps include the coupling of three monosaccharide moieties and dimerization and trimerization of the trisaccharide unit by glycosylations employing the 2'-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-D-mannose moiety by elaboration of its equatorial hydroxyl and axial methyl groups at C-3' in the disaccharide stage. 相似文献
34.
D. Ravinder T. Seshagiri Rao V. N. Muley K. B. Reddy 《Crystal Research and Technology》1990,25(12):1475-1483
The electrical conductivity (σ) and thermoelectric power (Q) of polycrystalline lithium zinc ferrites sintered at 1200 and 1300 °C was investigated as a function of temperature. The porosity and activation energy were calculated. It was found that the electrical conductivity is progressively increasing with increase of sintering temperature while the porosity and activation energy decrease continuously. The carrier concentration (n) and mobility (μ) of charge carriers has been discussed as a function of sintering temperature and temperature, respectively. 相似文献