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131.
Ultra-long single-crystalline trigonal selenium submicrotubes were synthesized using a facile one-step solution-phase approach with the assistance of nonionic surfactant Polyoxyethylene(20)sorbitan monolaurate (Tween-20), which turned out to be significant for the formation of ultra-long Se submicrotubes. XRD, Raman, SEM, and TEM were adopted to characterize the morphology, structure and phase composition of the as-prepared Se products. It was found that the length of the obtained Se submicrotubes was over 100 microm. By variation of the experimental parameters, the t-Se spheres, nanowires, and broken microtubes can be prepared. The possible growth mechanism of the ultra-long selenium submicrotubes was explained. In addition, we have also demonstrated that the synthesized ultra-long t-Se submicrotubes using the Tween-20-assisted approach can electrochemically charge and discharge with the high capacity of 265 mAh/g (corresponding to 0.97 wt % hydrogen in SWNTs) under normal atmosphere at room temperature. Cyclic voltammetry was adopted to investigate the adsorption-oxidation behavior of ultra-long selenium submicrotubes. It was observed that the morphology of the synthesized selenium products had a remarkable influence on their capacity of electrochemical hydrogen storage. These differences in hydrogen storage capacity are likely due to the size and density of tubes as well as the microcosmic morphology of different Se samples. The as-obtained ultra-long Se submicrotubes are expected to find wide applications in hydrogen storage, high-energy batteries, and optoelectronic, biologic, and catalytic fields as well as in the studies of structure-property relationships. This simple Tween-assisted approach might be extended to the preparations of one-dimensional nanostructures of tellurium and other anisotropic materials. 相似文献
132.
Potentiodynamic deposition of Prussian blue from a solution containing single component of ferricyanide and its mechanism investigation 总被引:1,自引:0,他引:1
Dai?Zhang Kang?Wang Dacheng?Sun Xinghua?XiaEmail author Hongyuan?Chen 《Journal of Solid State Electrochemistry》2003,7(9):561-566
Potentiodynamic techniques were used for the direct electrodeposition of Prussian blue nano-clusters from an acidic solution of ferricyanide. Electrochemical, EQCM, IR, AFM, and UV/vis measurements were carried out to characterize deposited nano-sized Prussian blue and to explore the formation mechanism. Results showed that ferricyanide could partially dissociate to free ferric and cyanide ions. The driving force of this dissociation is the formation of PB and the evolution of HCN. The optimal potential window for the potentiodynamic formation of PB from an acidic solution (pH 1.6) is between –0.5 V and 0.4 V. In addition, the influence of surface adsorption of CN- ions on the formation of PB was discussed.Dedicated to Professor W. Vielstich on the occasion of his 80th birthday. 相似文献
133.
茶叶中三氯螨杀醇残留量的快速HPLC测定法 总被引:3,自引:0,他引:3
用微量化技术处理茶叶样品,样品经石油醚提取、浓硫酸磺化后,用反相液相色谱分离、测定样品处理液中的三氯杀螨醇残留量,234nm检测,外标法定量。测定低限为0.5mg/kg,回收率为91.5%~99.3%,变异系数为1.53%~6.92%之间。 相似文献
134.
135.
Christov A Korol RM Dai E Liu L Guan H Bernards MA Cavers PB Susko D Lucas A 《Photochemistry and photobiology》2005,81(2):457-466
Altered collagen and elastin content correlates closely with remodeling of the arterial wall after injury. Optical analytical approaches have been shown to detect qualitative changes in plaque composition, but the capacity for detection of quantitative changes in arterial collagen and elastin content in vivo is not known. We have assessed fluorescence spectroscopy for detection of quantitative changes in arterial composition in situ, in rabbit models of angioplasty and stent implant. Fluorescence emission intensity (FEI) recorded at sites remote from the primary implant site was correlated with immunohistochemical (IH) analysis and extracted elastin and collagen. FEI was significantly decreased (P<0.05) after treatment with anti-inflammatory agents, and plaque area decreased on comparison with saline-treated rabbits after stent implant or angioplasty (Por=0.961) analysis were detected by multiple regression (MR) analysis. Good correlations also were found for FEI with elastin and collagen measured by high-performance liquid chromatography; MR analysis provided highly predictive values for collagen and elastin (R2>or=0.994). Fluorescence spectroscopic analysis detects quantitative compositional changes in arterial connective tissue in vivo, demonstrating changes at sites remote from primary angioplasty and stent implant sites. 相似文献
136.
Tetrahydrofurans (THFs) and tetrahydropyrans (THPs) are important core scaffolds frequently found in many molecules of medicinal importance. Herein, we report a novel copper-catalyzed hydroxycyclopropanol ring-opening cyclization methodology to synthesize di- or tri-substituted THFs and THPs. In this reaction, a strained C–C bond was cleaved and a new Csp3–O bond was formed to produce the aforementioned O-heterocycles. The new THF synthesis features a broad substrate scope, scalability, and good functional-group tolerability. It enabled us to complete the shortest enantioselective syntheses of hyperiones A and B (3 and 4 steps, respectively), which is significantly shorter than the previously reported two total syntheses (≥10 steps).A novel Cu-catalyzed hydroxycyclopropanol ring-opening cyclization was developed to synthesize substituted tetrahydrofuran/tetrahydropyran molecules including two norlignan natural products hyperiones A and B. 相似文献
137.
蒙旦树脂化学组成的研究 总被引:7,自引:5,他引:7
采用阴离子交换色谱和硅胶-氧化铝柱色谱对云南寻甸蒙旦树脂(XDSZ)、潦浒蒙旦树脂(LHSZ)、昭通蒙旦树脂(ZTSZ)和吉林舒兰蒙旦树脂(SLSZ)进行了族组分的分离。树脂游离酸,树脂结合酸,树脂烃和树脂醇在各树脂中的百分含量分别为XDSZ11.86,8.76,12.30,45.99;LHSZ15.89,13.91,4.90,45.99;SLSZ25.46,8.07,17.40,36.22;ZT 相似文献
138.
催化反应—导数示波极谱法测定痕量钨 总被引:4,自引:0,他引:4
在盐酸介质中,痕量钨对钛(Ⅲ)还原金莲花橙的缓慢反应有强烈催化作用,在NaOH介质莲花橙O于-0.50Vvs.SCE产生一灵敏的导数示波极谱波。据此,建立了一定检测限和测定范围分别为0.8ng/mL和1.6-80mg/mLW的催化反应-示波极谱新方法,用于钢和矿样中钨的测定,获得满意结果。 相似文献
139.
调查分析了庐山508名1-7岁儿童发中锌,铁,铜含量,并对其与儿童生长发育的关系进行了探讨。结果表明,微量元素与生长发育密切相关。 相似文献
140.