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91.
92.
Enzymes immobilized on the inner surface of an electrophoretic capillary were used to increase sensitivity and resolution in capillary zone electrophoresis (CZE). Sensitivity is enhanced by inserting a piece of capillary containing the immobilized enzyme into the main capillary, located before the detector, in order to transform the analyte into a product with a higher absorptivity. This approach was used to determine ethanol. In order to improve resolution, capillary pieces containing immobilized enzymes were inserted at various strategic positions along the electrophoretic capillary. On reaching the enzyme, the analyte was converted into a product with a high electrophoretic mobility, the migration time for which was a function of the position of the enzyme reactor. This approach was applied to the separation and determination of acetaldehyde and pyruvate. Finally, the proposed method was validated with the determination of ethanol, acetaldehyde, and pyruvate in beer and wine samples. 相似文献
93.
94.
H.S. Shin M.J. Dedicatoria 《Physica C: Superconductivity and its Applications》2010,470(20):1329-1333
In the case of 2G coated conductor (CC) tapes, it has been reported that thin–thick CC tapes with IBAD substrate showed a superior electromechanical property even at smaller bending radius compared with the cases of 1G BSCCO tapes. Considering the application of CC tapes it is significant to evaluate the transport property under operating environment, because CC tapes might experience a change in operating pressure that can affect its current carrying capacity due to temperature variation and deformation. This study was focused on the Ic degradation behavior in bent CC tapes under pressurized liquid nitrogen. Differently processed YBCO and SmBCO CC tapes with IBAD substrate are used as samples. The bending strain characteristics at elevated pressure levels were evaluated by using the ρ-shaped sample holder which can induce different bending strain values at pressured state. Depressurization and thermal cycling were performed to check the reversibility of Ic in CC tapes. Vacuuming tests were also carried out to investigate the characteristics of Ic at different LN2 temperature levels. 相似文献
95.
Chang‐Ling Yan Yan Lu Shu‐Yan Gao 《Journal of polymer science. Part A, Polymer chemistry》2007,45(10):1911-1919
The polymerization of 3‐aminophenylboronic acid in an aqueous environment was used for the first time to modify polystyrene microspheres for protein (lysozyme) molecular imprinting. Polystyrene microspheres were prepared by styrene polymerization in an aqueous emulsion with poly(vinyl alcohol) as a surfactant. Poly(3‐aminophenylboronic acid) was then grafted onto the surface of the polystyrene microspheres through oxidation by ammonium persulfate in an aqueous solution in the presence or absence of lysozyme or hemoglobin. Rebinding experiments were conducted to establish the equilibrium time and to detect the specific binding capacity and selective recognition. The results indicated that the microspheres, imprinted by the template protein lysozyme or hemoglobin, possessed specific recognition sites on the shells and had a high specific binding capacity for template proteins. The imprinted particles did not need to be ground or sieved and could easily reach the adsorption equilibrium, thus avoiding some problems of the bulk polymer. All these results demonstrate that the particles have potential applications as substitutes for bulk polymers in biological macromolecular affinity studies. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1911–1919, 2007 相似文献
96.
The construction and electrochemical response characteristics of poly (vinyl chloride) and poly (vinyl chloride) carboxylate membrane sensors for the determination of cyclophosphamide and ifosphamide are described. Based on the formation of an ion-pair complex between the drug cation and sodium tetraphenylborate, two poly (vinyl chloride) sensors, namely a cyclophosphamide membrane sensor and ifosphamide membrane sensor were fabricated. They show a linear response for both drugs over the concentration range 10−2–10−4 M with cationic slopes of 56 and 54.6 mV per concentration decade, for sensor 1 and sensor 2, respectively. Based on the interaction between the drug solution and the dissociated COOH groups in the poly (vinyl chloride) carboxylate, sensor 3 was fabricated. It shows a linear response for both drugs over the concentration range 10−3–10−5 M with a cationic slope of 49.7 mV per concentration decade. The direct potentiometric determination of cyclophosphamide and ifosphamide in their pharmaceutical preparations using the proposed sensors gave average recoveries of 101.3±0.6, 100.8±10.7 and 102.0±11.0% for the sensors 1, 2 and 3, respectively, which compares reasonably well with the data obtained using the British Pharmacopoeial method (1993). Sensors 1 and 2 were also used to follow up the stability of the drugs studied in the presence of their degradates. These degradation products have no diverse effect on the responses of sensors 1 and 2. 相似文献
97.
《Electroanalysis》2006,18(21):2099-2105
Nafion‐coated bismuth film electrodes (NCBiFEs) were used to investigate the redox behavior of and metal release from rabbit liver metallothioneins (MTs) in an acetate buffer. Owing to the permselective exchange between positively charged MT molecules and cations in Nafion and the absence of detectable MT adsorption at bismuth surface, a diffusion‐controlled Nernstian redox wave of MTs (Epc=?0.869 V) was observed for the first time. The Nernstian behavior of the diffusing MTs is in contrast to the voltammetric responses of MTs at thin mercury films or Nafion‐coated mercury film electrodes, which either result in the replacement of the metals originally present in MTs by mercury or lead to a noticeable MT adsorption. By avoiding these undesirable features, the NCBiFE provides an excellent milieu for voltammetric studies of different types of MTs and related isoforms, paving the way for studying the redox‐modulated metal transfer of MTs and understanding the biological role of MTs in heavy metal detoxification and essential metal regulations. 相似文献
98.
研究了用涂层柱分离I^-,NO^-2,NO^-3,SCN^-,MoO^2-4等5种具有紫外吸收的阴离了的毛细管电泳方法。采用涂层柱可以有效地抑制电渗流,因此无需在载体电解质溶液中加入电流改性剂。其优越性在于改善了由于电渗流改性剂与体积较大的阴离子发生离子对相互作用所导致的峰形拖尾现象,有助于准确定理。 相似文献
99.
Mohammad H.?HabibiEmail author A.?Zeini Isfahani A.?Mohammadkhani M.?Montazerozohori 《Monatshefte für Chemie / Chemical Monthly》2004,135(9):1121-1127
Summary. Photooxidation of ethylbenzene with oxygen to give ethylbenzene hydroperoxide has been achieved in a stirred photochemical reactor that was cooled by a water system by irradiation with a 400W high-pressure mercury lamp and using TiO2 powder and metal coated TiO2. The effects of the amount of copper or silver coated on TiO2 and of the temperature on the rate of oxidation have been investigated. It is suggested that thermal cleavage of the O–O bond and photochemically generated singlet oxygen should be considered as the initiating step in a radical chain mechanism. An optimum loading of 6% Ag or 4–5% Cu was observed for photooxidation of ethylbenzene. 相似文献
100.