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81.
Hiroshi Ito Vladimir Marousek Conrad Schuerch 《Journal of polymer science. Part A, Polymer chemistry》1979,17(5):1299-1307
1,6-Anhydro-2,3,4-tri-O-(p-methylbenzyl)-ß-D -galactopyranose (TXGal,M1) has been copolymerized with 1,6-anhydro-2,3,4-tri-O-benzyl-ß-D -mannopyranose (TBMan,M2), the products characterized by NMR, specific rotation, and viscosity, and the reactivity ratios calculated. The reactivity ratios r1 = 0.37 ± 0.15 and r2 = 38 ± 4 indicate that the anhydromannose derivative is about 100 times as reactive as that of anhydrogalactose. A comparison of glucose, mannose, and galactose copolymerizations suggests that the reactivity differences of the three propagating cations are comparatively small and the reactivity differences of the monomers large. This result is consistent with a mechanism proposed earlier. Methyl substitution on the aromatic rings of the p-xylyl groups inhibits the initiation process significantly relative to benzyl, but propagation only slightly. 相似文献
82.
Takeo Fujino Hiroaki Tagawa Takeo Adachi Hiroshi Hashitani 《Analytica chimica acta》1978,98(2):373-383
A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800–1100°C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UO2+x test sample is ±0.0008–0.001, if a correction is applied for atmospheric moisture absorbed during mixing. 相似文献
83.
Hideya Kawasaki Hiroshi Maeda 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):479-483
Effects of the surfactant concentration Cd and the NaCl concentration Cs on the electrophoretic mobilities U of the well-characterized polymer-like micelles have been investigated by the electrophoretic light scattering, using tetradecyldimethylamine oxide hemihydrochloride (C14DMAO·1/2HCl). At the high ionic strength of 0.1 mol kg−1 NaCl, the electrophoretic mobilities were independent of Cd (5 mM < Cd < 100 mM), despite the concentration-dependent micelle growth of the polymer-like micelles. This suggests that the electrophoretic mobility of the polymer-like micelle at high ionic strengths is independent of the contour length (i.e., the molecular weight), as found on linear polyelectrolytes. Somewhat surprisingly, the entanglements of the polymer-like micelles gave small effect on the electrophoretic mobilities in the examined range of the surfactant concentration above an overlap concentration. The mobilities of the polymer-like micelle decreased with √Cs in a single exponential manner in the range of Cs from 0.02 to 0.3 mol kg−1. It is suggested that the cylinder model can be applied to the electrophoretic mobilities of the polymer-like micelles at high ionic strengths (i.e. a free-draining behavior), since the persistence length of the polymer-like micelle (20 nm) is much larger than the Debye length at high ionic strength. 相似文献
84.
Tanaka K Mori M Xu Q Helaleh MI Ikedo M Taoda H Hu W Hasebe K Fritz JS Haddad PR 《Journal of chromatography. A》2003,997(1-2):127-132
In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression. 相似文献
85.
A procedure of analysis for small-angle X-ray scattering (SAXS) data has been established to obtain density fluctuation of supercritical fluids near the critical point. It is indispensable for the certain analysis to utilize both of high-quality SAXS data measured under stable thermodynamic condition and accurate P–ρ–T data in supercritical region. As a standard example, SAXS measurements have been performed for supercritical CO2, which is a suitable sample satisfying the condition for both experiment and analysis. The measurements were carried out along four isothermal conditions at reduced temperature of Tr = T/Tc = 1.020, 1.022, 1.043 and 1.064. Comparing the experimental density fluctuation with calculated one from the most reliable equation of state, the differences are within 8% at most. 相似文献
86.
Hiroshi Suda Masatoahi Motoi Masatoshi Fujii Shigeyoshi Kanoh Hiroshi Yoshida 《Tetrahedron letters》1979,20(47):4565-4568
Enantioselective reductions of prociral ketones with chiral hydride reagent prepared from optically active 2,2′-diamino-6,6′-dimethylbiphenyl and lithium aluminum hydride were accomplished in O.Y. more than 50%. 相似文献
87.
Masaaki Suzuki Yoshihumi Sato Hiroshi Akatsuka 《Plasma Chemistry and Plasma Processing》1996,16(3):399-415
The objective of the present work is to investigate the behavior of hydrogen in an atmospheric-pressure free-burning argon are when a small amount of hydrogen is added into the arc. A two-dimensional model calculation is carried out under the assumption that the ionization reaction of argon is in equilibrium and the reactions among hydrogen molecules, atoms, ions, and electrons are not necessarily in equilibrium. This calculation gives the following conclusion. The hydrogen mass fraction of 0.001 is too small to affect the flow and temperature fields markedly, and the concentration ratios among the hydrogen species are in equilibrium in the greater part of the arc region except for same parts with a steep temperature gradient. The hydrogen mass Junction, however, is not uniform in the me and, especially in the high-temperature region near the cathodes, over three dynes mass fraction of the hydrogen accumulates and flows downstream to cause a high flux of hydrogen atom toward the anode. This phenomena can be explained by the large difference between the diffusivity of hydrogen atom and that of hydrogen ion in argon ion. 相似文献
88.
Sahara R Ichikawa H Mizuseki H Ohno K Kubo H Kawazoe Y 《The Journal of chemical physics》2004,120(19):9297-9301
A Monte Carlo simulation is carried out to study thermodynamic properties of Cu-Au alloys using a face-centered-cubic (fcc) lattice-gas model. To obtain quantitatively accurate results, a Finnis-Sinclair-type potential, which has been widely used for molecular dynamics (MD) simulations, is employed. To overcome some shortcomings of lattice-gas models such as neglecting vibrational entropy, the potential is mapped onto the fcc lattice using the renormalization technique. The renormalized potential gives an improved Cu-Au phase diagram compared to the original MD potential applied directly on the lattice. 相似文献
89.
90.
[reaction: see text] An aqueous biphasic reaction system enables the direct use of allyl alcohol in the Tsuji-Trost reaction without the help of any activating reagents for allyl alcohol. The reaction conditions are neutral to basic, allowing the use of amines as the nucleophile. Theoretical calculations have elucidated the importance of hydration of the hydroxy group for the smooth generation of pi-allylpalladium species. 相似文献