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961.
Ceramic BaCe0.8Ho0.2O3-α with orthorhombic perovskite structure was prepared by conventional solid state reaction, and its conductivity and ionic transport number were measured by ac impedance spectroscopy and gas concentration cell methods in the temperature range of 600-1000 ℃ in wet hydrogen and wet air, respectively. Using the ceramics as solid electrolyte and porous platinum as electrodes, the hydrogen-air fuel cell was constructed, and the cell performance at temperature from 600-1000 ℃ was examined. The results indicate that the specimen was a pure protonic conductor with the protonic transport number of 1 at temperature from 600-900 ℃ in wet hydrogen, a mixed conductor of proton and electron with the protonic transport number of 0.99 at 1000 ℃. The electronic conduction could be neglected in this case, thus the total conductivity in wet hydrogen was approximately regarded as protonic conductivity. In wet air, the specimen was a mixed conductor of proton, oxide ion and electron hole. The protonic transport numbers were 0.01-0.09, and the oxide-ionic transport numbers were 0.27-0.32. The oxide ionic conductivity was increased with the increase of temperature, but the protonic conductivity displayed a maximum at 900 ℃, due to the combined increase in mobility and depletion of the carriers. The fuel cell could work stably. At 1000 ℃, the maximum short-circuit current density and power output density were 346 mA/cm^2 and 80 mW/cm^2, respectively. 相似文献
962.
A method to analyze human plasma proteins without fractionation, directly applying a plasma-matrix mixture on the target plate of a matrix-assisted laser desorption/ionization-time of flight-mass spectrometer (MALDI-TOF-MS), has been described. Peaks of ionized plasma proteins could not be detected applying a mixture of an undiluted plasma sample and a matrix solution, but they appeared when the plasma was diluted before mixing with the matrix. Tenfold diluted plasma provided well-resolved protein peaks in the m/z range from 4000 to 30,000. The addition of a simple post-crystallization washing procedure performed on the target plate further improved the quality of mass spectra. We numbered 58 peaks in the range of 4-160 kDa and 32 out of which were assigned to the plasma protein species which have been reported. Especially high sensitivity and resolution were obtained in the region < 30 kDa, where multiple isoforms of apolipoprotein A-I, apolipoprotein A-II, apolipoprotein C-I, apolipoprotein C-II, apolipoprotein C-III, and transthyretin could be assigned. Various post-translational modifications are involved in the isoforms, e.g., proteolytic cleavage, glycosylation and chemical modifications. This method will become complementary with the present electrophoretic techniques, especially for the analysis of low-molecular-mass proteins. 相似文献
963.
CE-MS has evolved into a strong alternative to LC-MS. Most of CE-MS applications deal with characterization and identification. However, quantitative aspects have gained importance in, e.g., pharmaceutical and biotechnological applications. Here we summarize and evaluate various methodological aspects in order to achieve sensitive and reproducible results. Similar to LC-MS, aspects of matrix influence on the electrospray process need to be carefully addressed when quantitative results are intended by CE-MS. Due to a more complicated coupling special emphasis needs to be put on the CE-MS interface. Generally linearity over more than three orders of magnitude can be achieved by CE-ESI-MS. Furthermore, a literature survey has been performed in order to give an overview over quantitative measurements performed by CE-MS. The precision can be doubled when changing from a structural related to an isotopically labeled internal standard. Thus a level of precision better than 5% RSD can be achieved. 相似文献
964.
Veyis Karako Handan Yavuz Adil Denizli 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,240(1-3):93-99
Interferons are potent biologically active proteins synthesized and secreted by somatic cells of all mammalian species. Dye-affinity adsorption is increasingly used for protein separation. Hollow fibers have several advantages as adsorbents in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow fibers to which Cibacron Blue F3GA was attached for adsorption of recombinant interferon-α (rHuIFN-α). The hollow fiber was characterized by scanning electron microscopy. These dye-carrying hollow fibers (35.8 μmol/g) were used in the rHuIFN-α adsorption-elution studies. The effects of initial concentration of rHuIFN-α, medium pH, ionic strength and temperature on the adsorption efficiency of dye-attached hollow fibers were studied in a batch system. The non-specific adsorption of rHuIFN-α on the hollow fibers was 1.2 mg/g. Cibacron Blue F3GA attachment significantly increased the rHuIFN-α adsorption up to 99.8 mg/g. Significant amount of the adsorbed rHuIFN-α (up to 94.8%) was eluted in 1 h in the elution medium containing 1.0 M NaCl. In order to determine the effects of adsorption conditions on possible conformational changes of rHuIFN-α structure, fluorescence spectrophotometry was employed. We resulted that dye-affinity hollow fibers can be applied for rHuIFN-α adsorption without causing any significant conformational changes. Repeated adsorption/elution processes showed that these dye-attached hollow fibers are suitable for rHuIFN-α adsorption. 相似文献
965.
966.
Quan HAN Hong Tao YAN* Zhen Jie QIAN Department of Chemistry Northwest University Xi抋n 《中国化学快报》2002,13(12)
Thermal lens spectrometry (TLS) is an excellent tool for trace analysis1. TLS allows the detection of absorbances of 10-7~10-8, concentration of ≈ 10-11 mol稬-1 and the analysis of 10-15 L volumes with ≈10-2 absorbing molecules2. Kinetic analysis is playing an increasingly important part in modern analytical chemistry. Therefore, TLS shows much promise in combination with kinetic analysis. However, there are few data on TLS applications in kinetic analysis method so far3~4. A ne… 相似文献
967.
The main thermodynamic characteristics of the adsorption of haloadamantanes on graphitized thermal carbon black were determined by experimental measurements and by calculations in terms of molecular-statistic theory of adsorption. Using experimental data, the Kovac retention indices were calculated and the optimum conditions for gas-chromatographic separation of haloadamantanes on stationary phases with different polarity were elucidated. The influence of the cage effect in the adamantane unit on the chromatographic properties of haloadamantanes was established. 相似文献
968.
STUDY OF Cu-Mu CATALYST FOR THE SYNTHESIS OF METHYL FORMATE AND METHANOL FROM SYNTHESIS GAS
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将一种新型的CuMn催化剂用于由合成气合成甲酸甲酯和甲醇,该催化剂表现出良好的反应活性和甲酸甲酯选择性。考察了反应温度、合成气压力及催化剂制备方法等对合成甲酸甲酯和甲醇的反应活性及选择性的影响。在反应条件下,产物收率最高达60.10g/(L·h),产物甲酸甲酯的选择性很高。用BET、XRD及XPSAuger等测试方法对催化剂的比表面、晶相组成以及铜、锰在催化剂中的价态进行了表征,并探讨了催化剂失活的原因。 相似文献
969.
970.
A. Voelkel 《Chromatographia》1987,23(3):195-198
Summary The possibility of evaluation of the parameters representing the dispersive solute-solvent interactions is presented. BN and Bs values can be used to describe the liquid phase polarity and to predict the retention indices of alcohols when the model
polyxyethylene glycol dialkyl ethers and their sulphur analogs are used as stationary phases. The possibility of the first
ionization potentials estimation is also presented. 相似文献