表面活性剂辅助合成CdWO4纳米棒和纳米线

以Na₂WO₄•2H₂O和CdCl₂ 为主要原料, 分别在十六烷基三甲基溴化铵(CTAB)和十二烷基苯磺酸钠(SDBS)表面活性剂中, 在180 ℃反应16 h, 水热制备了CdWO₄纳米棒和纳米线. 利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段对产物进行了表征, 并对其在室温下的发光特性进行了测定. 实验结果表明: 产物均为具有单斜结构的单相CdWO₄. 其中CdWO₄纳米棒具有单晶属性, 平均粒径约为63 nm, 长度近1 µm; 而CdWO₄纳米线具有多晶特性, 平均粒径约为12 nm, 长度达十几微米. 当激发波长为253 nm时均有460 nm强的发射峰, 其中CdWO₄单晶纳米棒的发光强度大于CdWO₄多晶纳米线. 分别对CdWO₄纳米棒和纳米线形成的可能机理进行了初步分析.     

Periodic solution of a neutral delay model of single-species population growth on time scales

By using a fixed point theorem of strict-set-contraction, we present some sufficient conditions for the existence of at least one positive ω-periodic solution to a neutral delay model of single-species population growth on time scales. The significance of the present paper is that we address an open problem introduced by Kuang [Kuang Y. Delay differential equations with applications in population dynamics. New York: Academic Press; 1993] on time scales.     

[FeFe]-Hydrogenase and its organic molecule mimics—Artificial and bioengineering application for hydrogenproduction

This study focuses on [FeFe]-hydrogenase and its metallorganic mimics in terms of electronic and photophysical properties, which can be applied to the electrochemical and/or photochemical production of molecular hydrogen. Natural [FeFe]-hydrogenase, synthetic mimics of its active site and recent progresses in hybrid-type hydrogen production, for example, inorganic-combination photoelectrochemical and photochemical hydrogen production, are reviewed.     

Modeling investigation of Sm0.5Sr0.5CoO3−δ–Ce0.8Sm0.2O2−δ cathode for proton-conducting ceramic fuel cell

Journal of Solid State Electrochemistry - Simulation of proton ceramic fuel cell is of great importance in understanding their working mechanisms. Cathode activation polarization is a critical...     

Colorimetric detection of hepatitis B virus (HBV) DNA based on DNA-templated copper nanoclusters

DNA detection plays an important role in early diagnosis of genetic disease. The conventional detection methods of DNA are based on expensive equipment, which do not meet the demands of developing countries. Thus, we developed a colorimetric method, which could be observed with naked eye and used copper nanoclusters for cost-effective. Moreover, the target of this method is the DNA in Hepatitis B virus that is one of the most popular chronic viral infections in developing countries over the past years. Our method was sensitive and the limit of detection was 12 × 10⁹ molecules. Three-base-pair mismatches target DNA was detected easily. These results revealed the favorable sensitivity and selectivity of this approach. Most importantly, our method may have potential applications in correct diagnosis of genetic disease and monitoring of gene therapy in the poverty-stricken areas.     

任意支承梁的差分离散系统及其刚度矩阵的振荡性

应用二阶中心差分公式,建立了任意支承的Euler梁的差分离散系统,导出了与之等效的弹簧-质点-刚杆模型．利用振荡矩阵理论,证明了上述系统的刚度矩阵的符号振荡性,完整的导出了正系统的充分必要条件．     

邻二氮菲荧光法测定氯碱厂阳极泥中痕量钌

研究了在乙酸-乙酸钠缓冲溶液中,在盐酸羟胺还原剂存在下,于水浴中加热近沸,保温5 min,钌与邻二氮菲形成1∶3络合物。它的荧光激发波长峰为448 nm,发射波长峰为586 nm。钌与荧光强度线性范围为0～10μg·(25 mL)-1。样品中的钌通过蒸馏分离,方法应用于氯碱厂阳极泥中钌的含量分析,具有满意的分析结果。     

Theoretical Studies of Optical Properties of Silver Nanoparticles

Optical properties of silver nanoparticles such as extinction, absorption and scattering efficiencies are studied based on Green＇s function theory. The numerical simulation results show that optical properties of silver nanoparticles are mainly dependent on their sizes and geometries; the localized plasmon resonance peak is red shifted when the dielectric constant of the particle＇s surrounding medium increases or when a substrate is presented. The influences of wave polarizations, the incident angles of light, the composite silver and multiply-layers on the plasmon resonance are also reported. The numerical simulation of optical spectra is a very useful tool for nanoparticle growth and characterization.     

Synthesis of ion-imprinted mesoporous silica gel sorbent for selective adsorption of copper ions in aqueous media

A new Cu(II) ion-imprinted sorbent was synthesized by a surface imprinting technique and characterized by FT-IR and SEM. Compared to the non-imprinted sorbent, the Cu(II) ion-imprinted sorbent had a higher adsorption capacity and selectivity for Cu(II). The static adsorption capacity of the Cu(II) ion-imprinted sorbent and non-imprinted sorbent for Cu(II) were 84.5 and 46.5 μmol?g^?1, respectively. The best selectivity coefficient over Zn(II) or Cd(II) ion was over 12. The relative selectivity coefficients of the sorbent for Cu(II) in the presence of Zn(II) and Cd(II) were 13 and 35, respectively. Furthermore, the new sorbent possessed a fast kinetics for Cu(II) sorption from aqueous solution with saturation time of <30 min, and could be used repeatedly. The standard deviation for 11 replicate determinations of 0.5 mg?L^?1 Cu(II) was 0.8%. This new Cu(II) ion-imprinted sorbent can be used as an effective solid-phase extraction material for the selective preconcentration and separation of Cu(II).     

Microwave-assistant synthesis of ordered CuO micro-structures on Cu substrate

A mild template-free mixed solution medium with the assistant of microwave method was successfully established to synthesize well-aligned CuO nanostructures. By varying process parameters such as the volume ratio of the mixed solution, different kinds of architectural structures can be controllably synthesized in large quantities. On the basis of the results, it is found that the polarity of the solution plays the key role in controlling the growth of the CuO crystal. The as-prepared CuO products were characterized using diverse techniques including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The gas sensor property investigation shows that the sensitivities to ethanol of the as-prepared CuO nanostructures are higher than those of normal CuO nanoparticles.