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71.
72.
The novel enantiomeric separation of acidic and neutral compounds by capillary electrochromatography with β‐cyclodextrin‐bonded positively charged polyacrylamide gels was examined. The columns used are capillaries filled with a positively charged polyacrylamide gel, a so‐called monolithic stationary phase, to which allyl carbamoylated β‐CD derivatives covalently bind. The capillary wall was activated first by bifunctional reagent to make the resulting gel bind covalently inside the fused‐silica tubing. Enantiomeric separations of sixteen acidic and two neutral compounds were achieved using the above‐mentioned columns and 200 mmol dm–3 Tris–300 mmol dm–3 boric acid buffer (pH 8.1) as a mobile phase. High efficiencies of up to 150 000 plates m–1 were obtained for dansyl‐DL‐amino acids. The within‐run and between‐run reproducibilities of retention time and separation factor were examined for three dansyl‐DL‐amino acids and warfarin. The relative standard deviations of the within‐run and between‐run reproducibilities of retention time were less than 1.2 and 1.3% over the six injections, respectively. Those of the separation factor were less than 0.3 and 0.2%, respectively. The gel‐filled capillaries were stable for at least four months with intermittent use. 相似文献
73.
Daiichi Koide Takeshi Kajiyama Ryuji Sato Haruki Tokumaru Yoshimichi Takano 《Optical Review》2014,21(5):541-544
We report on the recording characteristics of a near-field optical recording thin optical disk (NFR-TOD). We proposed a new cooling-less-type write strategy for recording, applied it to the NFR-TOD experimental system, and also applied a partial response maximum likelihood (PRML) signal processing, which was evaluated and optimized the PR coefficient for playback signals of the prototype NFR-TOD. The NFR-TOD has a track pitch of 160 nm and improved recording characteristics. The experimental results of the prototype NFR-TOD and the system indicate sufficiently low bit error rates (bERs) for recorded data at a fourfold higher recording density than the current Blu-ray disk. 相似文献
74.
Synthesis and antitumor properties of N1-acyloxymethyl derivatives of bis(2,6-dioxopiperazines) 总被引:1,自引:0,他引:1
J C Cai H L Shu C F Tang T Komatsu T Matsuno T Narita S Yaguchi Y Koide M Takase 《Chemical & pharmaceutical bulletin》1989,37(11):2976-2983
Many N1-acyloxymethyl derivatives VI of bis(2,6-dioxopiperazine) I, ICRF-154, were prepared and tested for antitumor activity. The treatment of I with formaldehyde gave a crystalline bis(N1-hydroxymethyl) derivative VII, which was acylated under various conditions to give bis(N1-acyloxymethyl) derivatives VI. Antitumor activity of VI against P388 leukemia in mice was studied. Several bis(N1-acyloxymethyl) compounds such as phenylacetyloxymethyl VI-6, methoxycarbonyloxymethyl VI-41, isobutoxycarbonyloxymethyl VI-44, and furancarboxymethyl VI-38 compounds were found to have potent antitumor activities. On the other hand, water-soluble esters having an amine or a carboxylic acid function in their acyl groups showed rather reduced activity. These bis(N1-acyloxymethyl) derivatives VI were presumably hydrolyzed into the parent bis(2,6-dioxopiperazine) I by nonspecific esterase in the body to exhibit their antitumor activity. 相似文献
75.
Naoyuki Koide Kazuyoshi Iimura Masatami Takeda 《Journal of polymer science. Part A, Polymer chemistry》1973,11(12):3161-3169
Studies have been made by NMR and ESR spectroscopy to elucidate the reaction mechanism in which the Ti(NEt2)4–AlMe3 catalyst system is involved. The two reaction products of Ti(NEt2)3Me and Al(NEt2)Me2 have been confirmed by NMR spectroscopy when Ti(NEt2)4 is reacted with AlMe3, and two kinds of paramagnetic species have been noted by ESR spectroscopy. It has been found that Ti(NEt2)3Me plays an important role as an active species for the polymerization of styrene. 相似文献
76.
Radiation sterilization of pancreatin preparation 总被引:1,自引:0,他引:1
The enzymatic activities (in detail, amylase-, lipase- and protease-activity) of gamma-irradiated pancreatin powder preparation decrease to 50-95% at doses range of 50 kR-8 MR. The dose-inactivation relation-ships vary depending on every different production lot. In the case of higher moisture content preparation as irradiation sample, amylase activities are more stable, the other side, protease activities are less stable. On the variation of these activities by gamma-irradiation, there are no difference between room temperature and lower temperature (-70 degrees C) as irradiation condition. The D10 values of contaminating bacteria and fungus (contamination number: about 1 X 10(3) cells/g and 9 X 10(2) spores/g) of a pancreatin preparation are 74 C/kg (280 kR) and 60 C/kg(230 kR). Then, these values are corresponded to 645 C/kg (2.5 MR) and 540 C/kg (2.1 MR) as perfect sterilization. 相似文献
77.
A model and theoretical equations are presented to investigate the enantiomeric recognition mechanism of primary amino compounds using an achiral crown ether with cyclodextrin by capillary electrophoresis (CE) and nuclear magnetic resonance (NMR). Association constants were calculated from CE and 1H NMR experiment results on the basis of the model and the equations. The key step of chiral recognition was identified from those values. Using CE analyses of three primary amino compounds [1-(1-naphthyl)ethylamine; 1-aminoindan; 1,2,3,4-tetrahydro-1-naphthylamine], the key step was identified with the equilibrium where the complex of a primary amino compound and 18-crown-6 becomes associated with 2,6-di-O-methyl-beta-cyclodextrin for all the three compounds. From the 1H NMR analyses of 1-(1-naphthyl)ethylamine, the key step was identified with the equilibrium where the complex of 1-(1-naphthyl)ethylamine and 18-crown-6 becomes associated with beta-cyclodextrin. 相似文献
78.
Field measurements of radioactivity were performed in highly contaminated areas around Chernobyl in the summer of 1990. Six radionuclides including the most dominant137Cs have been identified in soil samples through -ray spectrometry. The relation between the -ray dose rate above the ground and the radioactivity density in soils has been investigated. The external dose from deposited radiocesium for the period of 70 years after the deposition has been evaluated to be about 5 mSv per 1 and 0.5 Ci km–2 of137Cs and134Cs deposition, respectively. 相似文献
79.
A novel enantiomeric separation method by capillary electrochromatography with chiral crown ether-bonded negatively charged polyacrylamide gels is presented. Two kinds of chiral crown ether derivatives, (+)-tetraallyl 18-crown-6 carboxylate and (+)-18-crown-6 tetracarboxylic acid 2-allyl ester were synthesized and allowed to covalently bind to a negatively charged polyacrylamide gel, a so-called monolithic stationary phase, respectively. The gel was placed in fused-silica tubing, the walls of which had been activated with a bifunctional reagent to make the resulting gel bind covalently to the inner surface. Enantiomeric separations of 12 primary amino compounds were achieved using these columns and mobile phases of 200 mM triethanolamine-300 mM boric acid buffers with high efficiencies of up to 135000 plates m(-1). Both the within- and between-run reproducibilities of retention time and separation factor were good. The reproducibilities of retention time and separation factor for three different columns prepared from a different batch of monomers were acceptable. The gel-filled capillaries were stable for at least 13 months with intermittent use for 3 months followed by storage at room temperature for 10 months. The result of the optical purity test of alanine-2-naphthylamide is also described. 相似文献
80.
We investigate the implications of a seesawtype mass matrix, i.e.,M f?m LM F ?1 m R, for quarks and leptonsf under the assumption that the matricesm L andm R are common to all flavors (up-/down- and quark-/lepton-sectors) and the matricesM F characterizing the heavy fermion sectors have the form [(unit matrix)+b f (a democratic matrix)] whereb f is a flavor parameter. We find that by adjusting the complex parameterb f, the model can provide thatm t?m b while at the same time keepingm u~m d without assuming any parameter with hierarchically different values betweenM U andM D. The model with three adjustable parameters under the “maximal” top-quark-mass enhancement can give reasonable values of five quark-mass ratios and four KM matrix parameters. 相似文献