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991.
Influences of permeation of vanadium ions through PVDF-g-PSSA membranes on performances of vanadium redox flow batteries 总被引:6,自引:0,他引:6
Luo X Lu Z Xi J Wu Z Zhu W Chen L Qiu X 《The journal of physical chemistry. B》2005,109(43):20310-20314
The preparation and physical characterization of a poly(vinylidene fluoride)-graft-poly(styrene sulfonic acid) (PVDF-g-PSSA) membrane prepared by a solution-grafting method were described. These membranes exhibited high conductivity with a value 3.22 x 10(-2) S/cm at 30 degrees C. ICP studies revealed that the PVDF-g-PSSA membrane showed dramatically lower vanadium ion permeability compared to Nafion 117. Trivalent vanadium ions had the highest permeability through all these membranes in contrast to pentavalent vanadium ions with the lowest. The VRB with the low-cost PVDF-g-PSSA membrane exhibited a higher performance than that with Nafion 117 under the same operating conditions, and its energy efficiency reached 75.8% at 30 mA/cm(2). The performance of VRB with the PVDF-g-PSSA membrane can be maintained after more than 200 cycles at a current density of 60 mA/cm(2). 相似文献
992.
JunZhou Yong-zhiQiu Xiao-pengZang Chang-wangPan QiangChen JianShen Si-congLin 《高分子科学》2005,(1):93-102
N,N-dimethyl-N-methacryloyloxyethyl-N-carboxyethyl ammonium (DMMCA) was graft-copolymerized onto the surface of segmented poly(ether urethane) (SPEU) and PE film. The carboxybetaine structure on SPEU and PE film surfaces was confirmed by ATR-FTIR, XPS and water contact angle measurements. Through the experiments with platelet adhesion and protein adhesion assay in vitro, the two materials studied, including poly-DMMCA gel, all show excellent nonthrombogenicity. This confirms once again that the zwitterionic molecular structure on the surfaces of materials is essential for improving their nonthrombogenicity and biocompatibility. 相似文献
993.
MA Jianhua LIN Weizhen DU Fuqiang HAN Zhenhui YAO Side & LIN Nianyun .College of Biology Engineering Jimei University Xiamen China .Laboratory of Nanobiomedicine & Laboratory of Radiation Chemistry Shanghai Institute of Applied Physics Chinese Acade Sciences Shanghai China 《中国科学B辑(英文版)》2005,48(4):292-296
Quinones including menadione are ubiquitous in nature. They play important roles in aerobic respira- tion and photosynthesis[1,2]. In addition, exogenous quinones are used as antibiotics and anticancer drugs. Their function is closely related to their red… 相似文献
994.
Renqing Lü 《天然气化学杂志》2005,14(2):119-124
The density functional theory and the cluster model methods have been employed to investigate the interactions between ethanethiol and HZSM-5 zeolites. Molecular complexes formed by the adsorption of ethanethiol on silanol H3SiOH with two coordination forms, model Bronsted acid sites of zeolite cluster H3Si(OH)Al(OH)2SiH3 interaction with ethanethiol, aluminum species adsorbed ethanethiol have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using B3LYP hybrid method at 3-21G basis level for hydrogen atoms and 6-31G(d) basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms of H3Si(OH)Al(OH)2SiH3-ethanethiol, silanol-ethanethiol and Al(OH)3-ethanethiol have been studied. The calculated results showed the nature of interactions was van der Waals force as exhibited by not much change in geometric structures and properties. The preference order of ethanethiol adsorbed on HZSM-5 zeolite may be residual aluminum species, bridging hydroxyl groups and silanol OH groups from the adsorption heat. The adsorbed models of protonized ethanethiol on bridging hydroxyl OH groups and linear hydrogen bonded ethanethiol on bridging OH groups suggested in literature might not exist as revealed by this theoretical calculation. Possible adsorption models were obtained for the first time. 相似文献
995.
溶胶-凝胶法制备丙烯酸甲酯-衣康酸酐共聚物/SiO_2杂化材料 总被引:2,自引:0,他引:2
以丙烯酸甲酯( MA) 和衣康酸酐(Itn) 的无规共聚物和原硅酸四乙酯(TEOS) 作为有机相与无机相前驱体,以3 氨丙基三乙氧基硅烷(APTES) 为偶联剂,通过溶胶 凝胶过程制备出有机 无机杂化材料.并通过SEM、DSC 等方法考查了偶联剂用量对所得材料结构及性能的影响. 相似文献
996.
Statistics aided optimization for high-performance liquid chromatographic analysis of organic acids in tobacco 总被引:1,自引:0,他引:1
Qiu J 《Journal of chromatography. A》1999,859(2):153-158
HPLC analysis for organic acids in tobacco was optimized with the aid of statistical experimental design, a central composite face-centered design. In the design, only thirteen HPLC analyses were needed for identifying two optimal separation parameters. A Bio-Rad Aminex HPX-87H column was used for the analyses. An optimal separation for seven acids in tobacco was found at a temperature of 57 degrees C and a mobile phase of 0.032 N sulfuric acid solution, or at a temperature of 70 degrees C and a mobile phase of 0.024 N sulfuric acid solution, with a flow rate of 0.6 ml min(-1). 相似文献
997.
998.
助剂对CH4,CO2和O2制合成气反应催化剂性能的影响 总被引:13,自引:0,他引:13
考察了NiCaO-Al2O3催化剂中添加碱金属、碱土金属、稀土金属氧化物、CuO助剂及CaO含量对催化剂性能的影响。结果表明,10Ni-2K-2Cu15CaO-Al2O3催化剂对CH4、CO2和O2制合成气反应具有较高的催化活性、选择性和较好的抗积炭性能。通过TPR、CO-TPD、XPS和XRD对催化剂进行表征,发现K2O、CuO和CaO的添加削弱了活性组分Ni与载体Al2O3间的相互作用,增加Ni的电子密度,加速了CO与H2的脱附,从而抑制了CH4深度裂解积炭和CO歧化积炭。此外,这些助剂的添加也提高了Ni的分散度,增强了催化剂的抗积炭能力。 相似文献
999.
1000.
A simple and sensitive HPLC method for quantitative determination of guanidine in high salt and protein matrices was developed. The HPLC system consisted of an Agilent 1100 pump with an online degasser, a UV detector, an autosampler, and Dionex CS 14 cation-exchange guard (4 mm x 50 mm) and analytical (4 mm x 250 mm) columns. The mobile phase was 3.75 mM methanesulfonic acid (MSA) with a flow rate of 1 mL/min. The other analysis parameters were: 50 microL injection volume, 195 nm UV detection, and 21 min runtime. The limit of quantitation (LOQ) for guanidine HCl was determined to be 0.25 mg/L and the standard curve ranged from 0.25 mg/L to 10 mg/L. Sample preparation was required for the samples containing high protein concentrations. Proteins were removed by centrifuging a sample in a 30 K NanoSep centrifugal filter at 15,300 x g for 20 min. The method could determine guanidine accurately in sample matrices containing up to 200 mM sodium ion or up to 50 mM potassium ion. The method can be used for clearance testing of guanidine in biopharmaceutical products. 相似文献