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121.
Hu H Qiao M Xie F Fan K Lei H Tan D Bao X Lin H Zong B Zhang X 《The journal of physical chemistry. B》2005,109(11):5186-5192
The desulfurization of thiophene on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) has been studied in ultrahigh vacuum (UHV) by X-ray photoelectron spectroscopy (XPS). The Raney Ni or RQ Ni can be approximated as a hydrogen-preadsorbed polycrystalline Ni-alumina composite. It is found that thiophene molecularly adsorbs on Raney Ni or RQ Ni at 103 K. At 173 K, thiophene on alumina is desorbed, while thiophene in direct contact with the metallic Ni in Raney Ni undergoes C-S bond scission, leading to carbonaceous species most probably in the metallocycle-like configuration and atomic sulfur. On RQ Ni, the temperature for thiophene dissociation is about 100 K higher than that on Raney Ni. The lower reactivity of RQ Ni toward thiophene is tentatively attributed to lattice expansion of Ni crystallites in RQ Ni due to rapid quenching. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species on Raney Ni and RQ Ni at higher temperatures, which has been the dominant reaction pathway on Ni single crystals. By 473 K, the C 1s peak has disappeared, leaving nickel sulfide on the surface. 相似文献
122.
The anodic polymerization of 3-aminophthalhydrazide (luminol) and iron(II) tris 5-aminophenanthroline (Fe(phen-NH2)3(2+)) has been reported in this paper. A bilayer electrode was developed based on these polymers and the ITO conductive glass (denoted ITO[Fe(phen-NH2)3(2+)]luminol electrode). This electrode emitted light (lambdaem: 430 nm) as it was brought into contact with H2O2. At pH 10, the resulting electrochemiluminescence (ECL) showed a linear relationship with the concentration of H2O2 in the range of 10 microM(-1) mM. This bilayer electrode also showed an application potential for the detection of glucose after being further modified with glucose oxidase (denoted ITO[Fe(phen-NH2)3(2+)]luminol]GOx electrode). Although the resulting ECL decayed more rapidly in concentrated glucose solutions (e.g., I M) because of the consumption of luminol during use, the decay became less severe in diluted glucose solutions (e.g., 10 mM). According to the flow injection analysis, a linear relationship existed between the ECL and the concentration of glucose from 10(-5)-10(-3) M at pH 9. The detection limit could reach a level of 5 x 10(-5) M at this pH. 相似文献
123.
N-Methylpyrrolidine in cefepime for injection was determined by capillary electrophoresis with indirect UV detection. Best results were achieved with background electrolyte consisting of 10 mM creatinine adjusted to pH 3.8 with formic acid and an applied voltage of 30 kV in a bare fused-silica capillary. Indirect UV detection was performed at a wavelength of 225 nm. The application of a small amount of inlet pressure during the separation assisted the attainment of a stable baseline. The optimized method was validated regarding selectivity, linearity, accuracy, precision, ruggedness, repeatability and detection limits. Careful control of capillary conditioning enabled migration time precision values of <0.2% RSD. The use of an internal standard enabled precision values of <1% RSD to be obtained for peak area ratios. 相似文献
124.
ZHU Jun ZHANG Yun CHEN Hao CHE Yun-Xia ZHENG Ji-Min ② 《结构化学》2006,25(8):1011-1013
1 INTRODUCTION Nonlinear optics (NLO) is at the forefront of cur- rent researches because of its importance in provi- ding the key functions of frequency shifting, optical modulation, optical switching, optical logic and op- tical memory for the emerging … 相似文献
125.
催化燃烧是目前最有效的处理挥发性有机物(VOCs)技术之一. 本文从催化剂活性组分、催化剂载体、有效组分颗粒大小、水蒸汽的影响及催化燃烧反应中的积碳等几个方面, 对近年来催化燃烧处理VOCs的研究进行了总结. 分析表明: 贵金属催化剂的研究主要着重于选择有效的载体和双组分贵金属催化剂; 非贵金属催化剂的研究主要集中在高活性的过渡金属复合氧化物、钙钛矿和尖晶石型等催化剂的研制, 还有这些活性组分粒径大小及载体对催化燃烧VOCs反应活性的影响;此外, 在实际应用中,水蒸汽和催化剂积碳失活等问题对催化燃烧VOCs的反应也有很大影响. 本文的评述将为选择合适的催化燃烧技术处理VOCs污染物提供一定参考. 相似文献
126.
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128.
电化学法测定几种稀土贮氢合金的热力学函数 总被引:14,自引:0,他引:14
贮氢材料由于能可逆地吸放氢,得到了广泛地应用.特别是以贮氢材料为负极制成的氢镍二次电池,容量为同类型镉镍电池的1.5~2倍,且电压又相近,是镉镍电池的理想换代产品,受到人们普遍的关注。LaNi_(4.5)Mn_(0.5),LaNi_(4.9)Sn_(0.1)和La_(0.8)Nd_(0.2)Ni_(2.5)Co_(2.4)Al_(0.1)是电化学性能较优越的贮氢合金。LaNi_(4.5)Mn_(0.5)的电化学容量高,理论容量可达400mAh.g~(-1).LaNi_(4.9)Sn_(0.1)和La_(0.8) Nd_(0.2) 相似文献
129.
催化燃烧是目前最有效的处理挥发性有机物(VOCs)技术之一. 本文从催化剂活性组分、催化剂载体、有效组分颗粒大小、水蒸汽的影响及催化燃烧反应中的积碳等几个方面, 对近年来催化燃烧处理VOCs的研究进行了总结. 分析表明: 贵金属催化剂的研究主要着重于选择有效的载体和双组分贵金属催化剂; 非贵金属催化剂的研究主要集中在高活性的过渡金属复合氧化物、钙钛矿和尖晶石型等催化剂的研制, 还有这些活性组分粒径大小及载体对催化燃烧VOCs反应活性的影响;此外, 在实际应用中,水蒸汽和催化剂积碳失活等问题对催化燃烧VOCs的反应也有很大影响. 本文的评述将为选择合适的催化燃烧技术处理VOCs污染物提供一定参考. 相似文献
130.
A three-coil tungsten wire is used as electrode for the preconcentration of cadmium, which is then placed in a graphite tube for atomization and atomic absorption measurement. The heating parameters of the graphite furnace are optimized using the Modified and Weighted Centroid Simplex Method (MWCS), and computer program for automatic calculation. Sulphuric acid is selected as the supporting electrolyte for electrodeposition. The linear range of the calibration graph is 0.00-0.55 ng/ml. The detection limit is 0.01 ng/ml. For 0.1 ng/ml cadmium the coefficient of variation is 3.35% for ten parallel determinations. No interference occurs in the presence of more than 20 coexisting ions. Traces of cadmium in urine of normal people and in river water and the recoveries for cadmium are determined. The results are satisfactory. 相似文献