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25 September 2012, Volume 2012 Issue 5 Previous Issue    Next Issue

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Three-dimensional nickel-coated silicon microchannel plates for supercapacitors LIU Tao, WANG Fei, XU Shao-hui, WANG Lian-wei 2012, 2012 (5):  1-9.  Abstract ( 2675 )   PDF (3558KB) ( 2519 )   Save A unique three-dimensional Si-MCP/Ni/Ni(OH)2 structure for supercapacitor was produced. Chemical liquid deposition was carried out to grow nano-sized Ni(OH)2. The as-prepared Ni(OH)2 film consists of many intertwined nano-flakes with both the α- and β-Ni(OH)2 phases. The formation mechanism of Ni(OH)2 was introduced. The as-prepared and annealed materials were evaluated electrochemically by cyclic voltammetry and chronopotentiometry. The cyclic voltammetry results reveals a typical redox characteristic of the sample. A specific capacitance of 2 150 F/g was observed at a discharge current of 10 mA, and the structure has high stability in prolonged charging and discharging experiments. The capacitance of the annealed sample decreases as the annealing temperature increases. Surface morphology of the samples after 2 000 cycles and annealed samples were observed. Decrease of the surface area of Ni(OH)2 is consi-dered as the main reason of the capacitive loss. Owing to the large specific capacitance and good stability, the unique structure is suitable for electrochemical super-capacitors used in secondary power sources and devices. References | Related Articles | Metrics

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Micopolarization elements on p-aminoazobenzene film induced by femtosecond laser pulses PENG Xue-ying, JIA Tian-qing, SUN Zhen-rong 2012, 2012 (5):  10-15.  Abstract ( 2047 )   PDF (1860KB) ( 2693 )   Save Fabrication of nanostructures on a surface of p-aminoazobenzene polymer film illuminated by 400 nm and 800 nm femtosecond laser was studied. Ripples with periods of 210 nm and 500 nm were produced by linearly polarized 400 nm and 800 nm femtosecond laser pulses, respectively. The periods of the ripples increase with increasing the intensity of incident laser pulses. The interference of this diffracted optical wave with the incident beam gives rise to optical interference ripples. Gradient of surface tension is induced by the surface temperature gradient caused by the interfered light. The gradient of surface tension gives rise to the periodical ripple structures. Thick polymer film was made and illuminated by 400 nm femtosecond laser，and periodic nanostructures were also been observed. References | Related Articles | Metrics

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Characterization of a humidity sensor fabricated with SnO2 nano-spheres via dielectrophoresis CAO Chun-yue 2012, 2012 (5):  16-23,36.  Abstract ( 1917 )   PDF (2541KB) ( 2469 )   Save A relative humidity sensor was fabricated by dielectrophoresis (DEP) to connect with the sphere-shaped SnO2 nano-particles as sensing elements based on the Au micro-electrodes with the gap of 20 μm. the I-V curve obtained verified good electric conductivity of the Au/SnO2/SnO2/Au structure fabricated. The sensing properties were tested in a self-designed relative humidity measuring system. The high sensitivity and good repeatability were obtained. It was proved the sensing structure fabricated in the solution using DEP has good stability under varied humidity levels, even under a high humidity level. The proposed methodology can be easily applied to other nano-spheres and construction of other devices. References | Related Articles | Metrics

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Electrical conductivity properties of modified polyacrylonitrile/MWNTs composites ZHANG Jian, XU Xue-cheng 2012, 2012 (5):  24-30.  Abstract ( 2376 )   PDF (1824KB) ( 3104 )   Save The PAN was synthesised by solution polymerization, modified by heat-treatment and then blended with carbon nanotube to obtain the composites. The electrical conductivity of the composites increased by two orders of magnitude more than that unmodified. Fourier transform infrared spectroscopy (FTIR), Raman spectra and X-ray spectroscopy (XPS) were used to characterize the composites. The results showed that some nitrile were changed into imino, and the chain-like structure also transformed to the cyclic structure after heat-treatment. The strong π-π system was formed between π-electrons of MWNTs and the modified PAN. The interaction between the modified polyacrylonitrile and carbon nanotubes was greatly enhanced. The electrical conductivity was highly improved. References | Related Articles | Metrics

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Spin interactions in direct-gap semiconductors SUN Fang, TANG Zheng 2012, 2012 (5):  31-36.  Abstract ( 2454 )   PDF (1185KB) ( 2639 )   Save This paper studied spin interactions in a direct-gap system with the two-impurity Haldane-Anderson model, by using exact quantum Monte Carlo method. Exact numerical results revealed two types of magnetic correlation functions, and none of them showed clearly RKKY-type oscillatory behavior. Besides, it was observed that magnetic correlation in the system was complicated and multifactor controlled. The complex magnetic behaviors observed in this study would be helpful for understanding the magnetic properties of a gaped system, snch as the dilute magnetic semiconductors. References | Related Articles | Metrics

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Synthesis and electrochemical characterization of 3D VO2(B) nanostructures ZENG Min, SONG Chang-qing, JIANG Wen-tao, YIN Hai-hong, YU Ke 2012, 2012 (5):  37-44.  Abstract ( 2237 )   PDF (3889KB) ( 2281 )   Save We successfully fabricated VO2(B) nanostructures through a hydrothermal process. The microstructures and the corresponding electrochemical properties of as-synthesized materials were evaluated. Experimental results indicated that the morphology of the products can be changed by modifying concentrations of the reducing agent, and the nanoflowers composed of nanobelts perform better specific capacity and cycling properties than those composed of nanoflakes. Our results show that the VO2(B) nanostructures may have potential use in the anode material of Li-ion batteries. References | Related Articles | Metrics

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Development of a luciferase-based method for rapid cell viability detection ZHU Jing-jing, BAO Qiu-ying, WANG Yu-meng, XIA Gang 2012, 2012 (5):  45-53,84.  Abstract ( 2216 )   PDF (906KB) ( 2110 )   Save The firefly luciferase gene was PCR-amplified from plasmid pGL4.26 and subcloned into a bacterial overexpression vector pET24a. Expressed luciferase fusion protein was purified using Ni-NTA affinity chromatograph and its activity was confirmed using Bright-GloTM kit. Based on the ATP-dependency of luciferase reaction, we developed a cell viability assay, which is faster, more convenient, and more sensitive in detect cell viability than generally used MTT, CCK-8 and Alamar Blue methods. References | Related Articles | Metrics

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Study on carbamate pesticides by capillary electrophoresis with laser-induced fluorescence detection YANG Yu-lin, ZHAO Xiao-yin, ZHAO Wen-jie, ZHOU Tian-shu 2012, 2012 (5):  54-61.  Abstract ( 2826 )   PDF (608KB) ( 1707 )   Save A sensitive and rapid capillary electrophoresis method with laser-induced fluorescence detection (CE-LIF) was developed for the determination of carbamate pesticides (including (3,5-dimethylphenyl) N-methylcarbamate (XMC), and mercaptodimethur). In alkaline solution, carbamate was hydrolyzed to methylamine, which can be derivatized by 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and detected by CE-LIF. Several parameters which influence the hydrolysis, derivatization and electrophoresis separation, such as pH, concentration of buffer solution and concentration of NBD-Cl, were investigated. The detection limits of the three carbamates were 3.0×10-9、1.0×10-9 and 3.0×10-9 mol/L, respectively. The proposed method was successfully employed to determine the rate constants and activation energies for carbamates hydrolysis. References | Related Articles | Metrics

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Energy decay estimation for the nonlinear viscoelastic equation with nonlinear second-order boundary damping LU Jun, ZHANG Hong-wei 2012, 2012 (5):  63-68.  Abstract ( 2555 )   PDF (249KB) ( 2277 )   Save The exponential decay estimation of the energy for the nonlinear viscoelastic equation with general damped term was obtained by using Nakao's inequality, and the algebra decay estimation of the energy for the equation with polynomial damped term was given by the same inequality. References | Related Articles | Metrics

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Transient influence on the electromagnetic launch rail under a cosine function of the magnetic pressure LIU Feng, LIU Wen 2012, 2012 (5):  69-75,92.  Abstract ( 2281 )   PDF (498KB) ( 2367 )   Save This paper studied the friction damping factors that influence electromagnetic rail launching. An electrical magnetric launcher orbit was simulated into an elastic foundation beam under a movement loading, a mathematical model of beam was established by using Euler beam theory, and the analytic solution of the flexural deflections of an orbit involving exponential functions of the dynamics problem under a simple harmonic pressure was derived with the help of the integral transformation, the inverse transformation and so on. The results of the numerical examples with MATLAB software showed that the elasticity coefficient, the viscous external damping coefficient and the coulomb damping coefficient have different influences on the transient dynamic response. So it provides sufficient theory evidence about the initial value problem of solving a higher order partial differential equation and improving the performance of an electromagnetic emission device. References | Related Articles | Metrics

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Wavelet estimation for locally self-similar processes LU Zhi-ping, TAO Qin-ying 2012, 2012 (5):  76-84.  Abstract ( 1957 )   PDF (284KB) ( 2171 )   Save A new estimation method was proposed based on the maximal overlap discrete wavelet transform, which provided a good alternative for the estimation of the time-varying self-similarity parameters. It also included a simulation-based study using Monte Carlo method, which increases the accuracy of the estimation. Finally, an application was made on the vertical ocean shear measurements. References | Related Articles | Metrics

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Pricing option with transaction costs under the subdiffusive Black-Scholes model GU Hui, ZHANG Yun-xiu 2012, 2012 (5):  85-92.  Abstract ( 2401 )   PDF (289KB) ( 2327 )   Save This paper dealt with the problem of discrete time option pricing by the subdiffusive Black-Scholes model with transaction costs. A subdiffusive geometric Brownian motion was introduced as the model of underlying asset prices exhibiting subdiffusive dynamics. In the presence of transaction costs, by a mean self-financing delta-hedging argument in a discrete time setting, a pricing formula for the European call option in discrete time setting was obtained. References | Related Articles | Metrics

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Networked fault tolerant control of the uncertain singularly perturbed system with packet dropout WANG Yan-yan, LIU Wei, KONG Ling-zhi 2012, 2012 (5):  93-100.  Abstract ( 2110 )   PDF (336KB) ( 2612 )   Save Considering the networked packet dropout of a singularly perturbed system under actuator failure, the original system was transformed to a singularly perturbed uncertain switched system. Then, the difficulty arising in the boundary dynamic behavior caused by a small parameter was overcome by using the matrix inequality technique. Meanwhile, the feedback stabilization of the singularly perturbed uncertain switched system was studied under some certain data dropout rate. Further, the design method of a controller and the sufficient condition of stabilization of the system were presented. Finally, a numerical example was given to illustrate the effectiveness of the proposed method. References | Related Articles | Metrics

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Positive solutions of the semipositone three-point boundary value problem on time scales WANG Ying 2012, 2012 (5):  101-108.  Abstract ( 2107 )   PDF (174KB) ( 2212 )   Save The existence of positive solutions for semipositone three-point boundary value problem on time scales was discussed, by using the Leggett-Williams fixed point theorem; the existence of at least two positive solutions was obtained. The results extend and improve some known results. As an application, an example was given to demonstrate the main result. References | Related Articles | Metrics

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Multiple solutions for ${\bm p}({\bm x})$-Laplacian problems in ${\bf R}^{\bm N}$ CHEN Zi-gao 2012, 2012 (5):  109-119.  Abstract ( 3413 )   PDF (221KB) ( 2676 )   Save By using the fountain theorem and the dual fountain theorem, respectively, the existence  and multiplicity of solutions for $p(x$)-Laplacian equations in $\mathbf{R}^{N}$ were studied, assumed that one of the perturbation terms $f_1(x,u),\, f_2(x,u)$ is superlinear and satisfies the Ambrosetti-Rabinowitz type condition and the other one is sublinear. The discussion was based on variable exponent Lebesgue and Sobolev spaces. References | Related Articles | Metrics

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An upper bound for the vertex-distinguishing star edge chromatic number of graphs LIU Xin-sheng, LU Wei-hua 2012, 2012 (5):  120-126.  Abstract ( 2243 )   PDF (197KB) ( 2621 )   Save The vertex-distinguishing star edge chromatic number of $G$, denoted by $\chi'_{\rm vds}{(G)}$, is the minimum number of colors in a vertex-distinguishing star edge coloring of $G$. The vertex-distinguishing star edge colorings of some particular graphs were obtained. Furthermore, if $G(V,E)$ is a graph with $\delta\geqslant 5$, and $n\leqslant  \Delta^7$, then $\chi'_{\rm vds}{(G)}\leqslant 14\Delta^2$, where $n$ is the order of $G$, $\delta(G)$ is the minimum degree of $G$, and $\Delta(G)$ is the maximum\linebreak degree of $G$. References | Related Articles | Metrics

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Space theory on graphs: The linearly independence methods in graph theory (I) REN Han WU Hao 2012, 2012 (5):  127-144.  Abstract ( 2371 )   PDF (459KB) ( 2356 )   Save In this paper we survey some important results and methods applied in graph theory and related topics. Different from the classical combinatorial matrix methods used in the fields such as the spectral theory of graphs, we concentrate on the finite linearly spaces over various kinds of number fields and their actions and influnces on the structural graph theory. Related Articles | Metrics