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121.
Yoshinori Kamiya Takuji Hirose Keishin Mizoguchi Yasutoshi Naito 《Journal of Polymer Science.Polymer Physics》1986,24(7):1525-1539
A gravimetric method for determining precisely the solubility of gases in polymers at high pressure is described. The solubilities of N2 and CO2 in low-density polyethylene (LDPE); CO2 in polycarbonate (PC); and N2, CH4, C2H6, and CO2 in polysulfone (PSUL) have been measured as a function of pressure up to 50 atm. Most of the measured sorption isotherms agreed closely with published data, but reproducible and time-dependent hysteresis in the sorption of CO2, C2H6, and CH4 in glassy polymers, PC, and PSUL, was observed in this study for the first time. Like the well known conditioning effect of high-pressure CO2 on the sorption capacity of glassy polymers, these hysteresis phenomena are believed to be due to the plasticizing effect of sorbed gases. On the basis of the current data, the dual-mode sorption model including the plasticization by sorbed gas is discussed and a primitive equation for the concentration of sorbed gases in a quasiequilibrium state of sorption or desorption is proposed. 相似文献
122.
Furkal E. Smolyakov A. Hirose A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(2):198-207
Nonlocal ion transport in a weakly ionized plasma with a strong electric field is analyzed. It is assumed that charge-exchange interactions are the main mechanism of ion scattering. Ion density and drift velocity are determined for nonuniform time varying electric field by using both the direct solution of the kinetic equation and the Chapman-Enskog-type approach. The ion mean velocity is given by an integro-differential operator applied to the electric field. Ion density and drift velocity exhibit resonant behaviour when ω≃kW0, which corresponds to the resonance between ions moving with average velocity W0 and wave traveling with the phase velocity ω/k 相似文献
123.
Abe K Amako K Arai Y Asano Y Chiba M Chiba Y Daigo M Emura T Endo I Fukawa M Fukui T Fukushima Y Haba J Haidt D Hayashibara I Hemmi Y Higuchi M Hirose T Hojyo Y Homma Y Hoshi Y Ikegami Y Ishihara N Kamitani T Kanematsu N Kanzaki J Kikuchi R Kondo T Koseki T Kubo K Kurashige H Matsui T Minami M Miyake K Mori S Nagashima Y Nakamura T Nakano I Odaka S Ogawa K Ohama T Ohsugi T Ono A Osabe H Saito H Sakae H Sakamoto H Sakamoto S Sakano M Sakuda M Sasao N Sato M Shioden M Shirai J Suekane F 《Physical review letters》1988,61(8):915-918
124.
125.
T. Hirose Y. Mi S. A. Stern Anne K. St. Clair 《Journal of Polymer Science.Polymer Physics》1991,29(3):341-347
The solubility of CO2 and CH4 in five polyimides was measured at 35.0°C and at pressures up to 10 atm (147 psia). The concentration of the penetrant gases dissolved in the polymers can be represented satisfactorily as a function of penetrant pressure by the “dual-mode sorption” model. The solubility coefficients for CO2 and CH4, S(CO2) and S(CH4), increase in the polyimide order: The magnitude of the solubility coefficients appears to depend primarily on the intermolecular forces between the penetrant gases and the polymers. The values of these coefficients are greater for the polyimides with larger mean interchain spacings, but no one-to-one correspondence appears to exist in this respect. The lower solubility of CO2 in PMDA-4,4'-m-APPS compared with that in the 6FDA polyimides may be due to the lower “excess” free volume of the former polymer. The ratio S (CO2)/S (CH4) varies relatively little for a variety of PMDA and 6FDA polyimides. 相似文献
126.
The stabilities of urokinase (UK) in aqueous solution were investigated at pH 5.0-8.0 in the presence (1.0-3.0 x 10(-3) M) and absence of sodium bisulfite (SBS) both under scattered light (1000 lux) and in the dark using the fluorogenic substrate method. Increasing concentrations of SBS tended to increase the inactivation of UK. In the presence of SBS, with the increase in the pH value, UK gained in stability in the pH range of 5.0-8.0. The stability of UK in the presence of SBS in the dark was larger than that under scattered light, especially at pH 5.0. Therefore, it was suggested that the difference in the residual activities of UK between under light and in the dark was due to free radicals formed during the autooxidation of bisulfite under scattered light. UK was stabilized by glucose in the presence of SBS both under scattered light and in the dark. One reason for this phenomenon was postulated to be the formation of inactive bisulfite-glucose addition compound. The degradation products of UK during storage in a solution containing SBS were investigated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. UK was revealed to be split into M.W. 36000 form and M.W. 20000 form by SBS. 相似文献
127.
[reaction: see text]. CAN is a good reagent for the transformation of 2-hydroxyethyl ether units to alcohols. Significantly, many functional groups can tolerate the reaction conditions, although they do not survive under many previously reported removal conditions. The reaction mechanism is clarified. 相似文献
128.
Summary The dependence of the capacity factor (k′) on the concentration of the organic modifier (D) in the aqueous binary mobile phase
in reversed-phase high-performance liquid chromatography has been investigated to evaluate the hydrophobicity of the solute
molecule. The r-values, defined as the slope of log k′ vs. log(1/D) plots, were measured for various solutes and related to
the non-polar surface area and the partition coefficients. The r-value was found to be a good indication of solute hydrophobicity.
Detailed investigation of the results allowed to consider statistically the molecular posture of the solute adsorbed onto
the stationary alkyl ligand. 相似文献
129.
Kazuo Kamaike Kumi Hirose Yoshihiro Kayama Etsuko Kawashima 《Tetrahedron letters》2004,45(30):5803-5806
The phosphorodithioate octamer [(TpS2)7T] was efficiently synthesized using bis(2,6-dimethylphenyl) phosphorochloridate as a coupling agent by application of the H-phosphonothioate method, where oxidation was facilitated using elemental sulfur following completion of oligonucleoside H-phosphonothioates assembly, as with the standard H-phosphonate method. 相似文献
130.
p-Nitrobenzenediazonium tetrafluoroborate dissolved in dimethylsulfoxide (DMSO) at 50° forms p-nitrophenol in 88–90% yield. The phenolic oxygen atom originates exclusively from the oxygen atom of DMSO as demonstrated by the use of 18O-labelled DMSO. The first-order rate of dediazoniation is the same under N2 as it is in the presence of air. The rate is little influenced by the addition of benzene or iodobenzene. However, the products formed in the presence of these additives are significantly different. UV. spectra and the reactivity of diazonium salt solutions in DMSO when mixed with reagents in aqueous solution demonstrate that a relatively stable charge-transfer complex is formed between the diazonium ion and DMSO. The product analyses and the kinetic and spectral results of dediazoniation in DMSO with and without additives are consistent with a mechanism in which the rate-limiting step is the formation of a p-nitrophenyl radical from the charge-transfer complex. p-Nitrophenol and the products with benzene and iodobenzene are formed in subsequent fast competition steps. In the presence of small amounts of pyridine the dediazoniation is much faster and follows a different kinetic law. Pyridine effectively competes with DMSO in the reaction with diazonium ions. 相似文献