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11.
Nishi K. Bhardwaj Viet Hoang Vinh Dang Kien L. Nguyen 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,290(1-3):222-228
A wide range of kraft pulps from radiata pine produced by low-temperature kraft pulping in flow-through reactors was assessed for carboxyl and hexenuronic acid (HexA) contents using the conductometric titrations and UV spectrophotometer, respectively. The Kappa number of pulps varied from 20.8 to 84.7 when using a cooking liquor of 1 M effective alkali as Na2O, 25% sulfidity, and cooking time of 100–250 min. The experimental results showed that the carboxyl groups (including HexA) and HexA groups dissolved and their residual values in the pulp samples correlate linearly with Kappa number and pulp yield. The dissolving rate of all carboxyl groups is much faster than the loss of HexA. The HexA/lignin ratio decreased non-linearly with Kappa number. 相似文献
12.
Morihiko Matsumoto Toshihiro Ichino J. Steven Rutt Shiro Nishi 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2551-2558
Dual-phase polymer electrolytes (DPE) that have high ionic conductivity (> 10?3 S/cm) and good mechanical strength were prepared by mixing NBR and SBR latices and casting films. The latex films absorbed large quantities of lithium salt solution (e.g., 1M lithium perchlorate in γ-butyrolactone) to obtain DPE films but did not dissolve with swelling. The NBR phase is polar and was impregnated selectively with the polar lithium salt solution, whereas the SBR phase is nonpolar and formed a mechanically-supportive matrix. Transmission electron microscopic (TEM), electron energy loss spectral (EELS), and energy-dispersive x-ray (EDX) analyses showed microscopically the dual-phase structure. Evidence for swelling by lithium salt solution was found only in the NBR phase and not in the SBR phase by EDX microanalysis. Ionic conductivity as a function of NBR content or swelling degree showed clearly that a percolation threshold for ionic conductivity exists. © 1994 John Wiley & Sons, Inc. 相似文献
13.
Hideo?AkisadaEmail author Masakatu?Ishihara Mitiko?Nishi Masaaki?Higake Seiki?Ishimaru Junko?Nishida 《Colloid and polymer science》2003,281(10):993-997
The partial molal volumes of two series of homologous surfactants, n-alkylammonium decanesulfonates and a, ?-alkanediammonium nonanesulfonates, were measured below and above their CMC in aqueous solution. Their counterions were n-alkylammonium and a, ?-alkanediammonium. The relationship between the partial molal volume and the chain length of the counterion below the CMC had an inflection point. The relationship between them, above the CMC, was almost linear. In the case of the alkylammonium salts, the values of the volume change of micellization were almost the same when the chain length of the counterions was shorter than the butyl, and increased with an increase in the chain length when it was longer than the propyl. In the case of the alkanediammonium salts, the volume change of micellization showed a small decrease with the chain length when it was shorter than octane, and was very large for the nonane ammonium salt. The large positive increase in the volume change with the increase in the chain length of the counterion can be explained by the hydrophobic interaction between the alkyl chain of the counterion and the hydrophobic core of the micelle. 相似文献
14.
Complex shear modulus at 33 kc./sec. is measured at temperatures of ?150–150°C. for amorphous selenium and crystalline selenium with different crystallinities. The dielectric relaxation at 10 kc./sec. to 3 kc./sec. to 3 Mc./sec. is observed at temperatures of ?32–25°C. for iodine-doped crystalline selenium. It is concluded from the results of this study and of others' that selenium exhibits four relaxations, α, β γ, and δ, in order of descending temperature. The β relaxation is observed only in the amorphous sample above the glass temperature and is assigned to the primary relaxation. The α, γ, and δ relaxations are found in the crystalline selenium. The α relaxation, which is prominent in a highly crystalline sample, is assigned to the crystalline relaxation. The γ and δ relaxations increase in peak height with decreasing crystallinity and are attributed to the disordered region in the crystalline selenium. The dispersion map (logarithm of frequency versus reciprocal absolute temperature of loss maximum) of selenium is presented. 相似文献
15.
The chiral separation of trimetoquinol hydrochloride, which is a bronchodilator (Inolin), and three related compounds by micellar electrokinetic chromatography was investigated using a bile salt as a chiral surfactant. Enantiomers of these compounds, except laudanosoline, were successfully separated within 12 min using a separation tube of effective length 500 mm × 0.05 rum i.d. and a 0.05 M sodium taurodeoxycholate solution of pH 7.0. The observed theoretical plate numbers of the peaks were ca. 150000. Chiral recognition was affected by the structure of bile salts, the pH of the buffer solutions used and the structure of the solutes. Of four kinds of bile salts, successful chiral separation was achieved only using sodium taurodeoxycholate solution under neutral conditions. The method was applied to the optical purity determination of trimetoquinol hydrochloride. The effects of surfactant concentrations and some additives to the micellar solution are briefly described. 相似文献
16.
The kinetics of the transfer of Erythrosine B dianions (EB2–) and Eosin Y dianions (EY2–) across the 1,2-dichloroethane|water interface, studied using ac-modulated voltfluorometry, is compared with that of Rose Bengal dianions (RB2–). All three exhibit anomalous phase angles, showing the transient adsorption of these ions at the interface. The apparent standard rate constants are 9.0 × 10–3 and 1.3 × 10–2 cm s–1 for EY2– and EB2– at 25° (cp. 1.4 × 10–2 cm s–1 for RB2–). The slight decrease in the rate in the order RB2–, EB2–, and EY2– may be associated with the increasing polarity of the ions, which endows the ions with a stronger interaction with water, resulting in the slower rotational dynamics of the ions on crossing the interface. 相似文献
17.
Momoko Ishida Rika Ohara Fuka Miyagawa Hiroe Kikuzaki Kosuke Nishi Hiroyuki Onda Nanami Yoshino Takuya Sugahara 《Molecules (Basel, Switzerland)》2022,27(13)
Cuminum cyminum L. (cumin) is an annual plant of the Umbelliferae family native to Egypt. We previously showed that the aqueous extract of cumin seeds suppresses degranulation by downregulating the activation of antigen-induced intracellular signaling molecules in rat basophilic leukemia RBL-2H3 cells. However, the active substances in the extract have not yet been identified. Accordingly, herein, we aimed to ascertain the water-soluble substances present in cumin seeds that inhibit degranulation, which led to the identification of umbelliferose, a characteristic trisaccharide present in plants of the Umbelliferae family. Our study is the first to reveal the degranulation-suppressing activity of umbelliferose, and quantification studies suggest that cumin seed powder contains 1.6% umbelliferose. Raffinose, an isomer of umbelliferose, was also found to significantly suppress antigen-induced degranulation, but less so than umbelliferose. Both umbelliferose and raffinose contain sucrose subunits in their structures, with galactose moieties bound at different sites. These differences in structure suggest that the binding of galactose to the sucrose subunit at the α1-2 bond contributes to its strong degranulation-inhibiting properties. 相似文献
18.
Oxidation of indans and tetralin derivatives to their corresponding indanones and tetralones is of considerable value i n organic synthesis and many methods have been reported for accomplishing this conversion. Traditionally these oxidations are performed with chromic acid in acetic acid and the yields in general are moderate. Recently Eisenbraun4 has studied indetail the benzylic oxidation with the Jones reagent and compared the selectivity and yield of oxidation with other chromium(V1) reagents like bipyridinim chlorochrmate, (BiPCC). It was found that there was no improvement in yield and in the case of BiPCC a molar ratio 16% 1 (oxidant: substrate) was employed to get 相似文献
19.
1,5-Dihydroxynaphthalene and its derivatives can be oxidized by molecular oxygen in the presence of catalytic amounts of salcomine under neutral conditions to afford the corresponding 1,4-naphthoquinones as the major products. 相似文献
20.