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Lin H.,Yuxi Normal University | Li M.,Peking University | Mihailovic D.,Jozef Stefan Institute
Electrochimica Acta | Year: 2015

A novel electrochemical sensor based on a new kind of nanomaterials Mo6S9-xIx nanowires modified glassy carbon electrode (GCE) was constructed for simultaneous determination of cadmium(II), lead(II) and copper(II) using differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters such as the modified amount, pH, deposition time and deposition potential were optimized. Under the optimal conditions, the stripping peak currents increase linearly with increasing concentrations of Cd(II), Pb(II) and Cu(II) ions in the ranges of 0.5∼150 μg·L-1, 1.5∼450 μg·L-1 and 0.8∼240 μg·μg·L-1, 1.5∼450 μg·L-1 and 0.8∼240 μg·L-1, respectively. And the limits of detection (S/N = 3) are estimated to be 0.10 μg·L-1 for Cd (II), 0.45 μg·L-1 for Pb(II) and 0.20 μg·L-1 for Cu(II), which are two orders of magnitude lower than those obtained at the unmodified electrodes. Most importantly, the sensor has been successfully applied to the determination of trace metal ions in the tap water samples. This developed electrochemical sensor exhibits high sensitivity, good stability and reproducibility. © 2014 Elsevier Ltd. All rights reserved.

Xie J.,Southwest University | Zhang X.,Southwest University | Wang H.,Southwest University | Zheng H.,Southwest University | And 2 more authors.
TrAC - Trends in Analytical Chemistry | Year: 2012

Recently, the intrinsic enzyme-like activity of nanoparticles (NPs) has become a growing area of interest. Compared with natural enzymes, these enzyme-like NPs are stable against denaturing, low in cost, and highly resistant to high concentrations of substrate. These advantages make them promising in various applications.In this review, we focus on recent advances in NPs as enzyme mimetics and their analytical and environmental applications. We pay special attention to the enzyme-like activity of magnetic NPs, cerium-oxide NPs, noble-metal NPs, carbon and other nanomaterials. © 2012 Elsevier Ltd.

Song M.,Yuxi Normal University | Ge Y.,Nanyang Normal University
Computers and Mathematics with Applications | Year: 2010

In this paper, the (G′/G)-expansion method is employed to solve the (3 + 1)-dimensional Kadomtsev-Petviashvili (KP) equation, the (3 + 1)-dimensional potential-YTSF equation and the (3 + 1)-dimensional Jimbo-Miwa (JM) equation. Exact traveling wave solutions are obtained. The traveling wave solutions are expressed in terms of hyperbolic functions, the trigonometric functions and the rational functions. © 2010 Elsevier Ltd. All rights reserved.

A linear time-delayed feedback is introduced into the bistable system driven by cross-correlated noises to control the stochastic resonance (SR) induced by the multiplicative periodic signal. The expression for the signal-to-noise ratio (SNR) of the system is derived in the small delay approximation and the adiabatic limit. By numerical computations, the effects of the delay time and strength of its feedback on the SNR are analyzed. The results indicate that the SR phenomenon can be enhanced or suppressed by adjusting the delay time and feedback strength. The influence of the time-delayed feedback on the SR depends not only on the sign of feedback strength, but also on the initial condition of the system. Moreover, both the delay time and the feedback strength can induce the critical behavior on the SR under given conditions. © 2010 The Royal Swedish Academy of Sciences.

Li Z.,Yuxi Normal University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

In this paper, without assuming the boundedness of activation functions, by applying continuous theorem of coincidence degree theory and the theory of calculus on time scales, we obtain some criteria for the existence exponential stability of periodic solutions to impulses Cohen-Grossberg neural networks with delay on time scales. Finally, an example is given to illustrate our results. © Springer International Publishing Switzerland 2016.

Liu Y.,Yuxi Normal University
Theoretical Computer Science | Year: 2010

The proposition "For composable thin codes Y and Z, the composition Y {ring operator} Z is maximal if and only if Y and Z are maximal" put forward by J. Berstel and D. Perrin in their book "Theory of Codes" is well known. Is the proposition also true without the assumption that Y and Z are thin? We give an example showing that the answer is negative. Furthermore, several generalizations of the above proposition are also given. © 2009 Elsevier B.V. All rights reserved.

Jia Z.-L.,Yuxi Normal University
International Journal of Modern Physics B | Year: 2011

The effects of noise correlation and time delay on the transient properties of a cancer growth system are studied in terms of the mean first-passage time (MFPT), which provides a measure of the mean extinction time of the tumor cell population. The results indicate that the additive and multiplicative noises can induce the noise-enhanced stability (NES) effect. The increasing of the delay time weakens the NES effect in the presence of two noise sources and induces a shift of the maximum of the MFPT towards smaller values of the noise intensities. The increasing of cross-correlation strength between noises can only restrain the NES effect induced by the multiplicative noise and can induce a shift of the peak of the MFPT towards larger values of the noise intensities. © 2011 World Scientific Publishing Company.

Song M.,Yuxi Normal University | Cao J.,Yuxi Normal University | Guan X.,Yuxi Normal University
Mathematical and Computer Modelling | Year: 2012

In this paper, we investigate the Whitham-Broer-Kaup-Like equations. Some explicit expressions of solutions for the equation are obtained by using the bifurcation method and qualitative theory of dynamical systems. These solutions contain kink-shaped solutions, blow-up solutions, periodic blow-up solutions and solitary wave solutions. Some previous results are extended. © 2011 Elsevier Ltd.

Zhao K.,Yunnan University | Zhao K.,Yuxi Normal University | Ye Y.,Yunnan University
Nonlinear Analysis: Real World Applications | Year: 2010

By using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of four positive periodic solutions for two species periodic LotkaVolterra predatoryprey system with harvesting terms. An example is given to illustrate the effectiveness of our results. © 2009 Elsevier Ltd. All rights reserved.

This paper investigates the stochastic resonance (SR) phenomenon induced by the multiplicative periodic signal in a cancer growth system with the cross-correlated noises and time delay. To describe the periodic change of the birth rate due to the periodic treatment, a multiplicative periodic signal is added to the system. Under the condition of small delay time, the analytical expression of the signal-to-noise ratio RSNR is derived in the adiabatic limit. By numerical calculation, the effects of the cross-correlation strength λ and the delay time τ on RSNR are respectively discussed. The existence of a peak in the curves of RSNR as a function of the noise intensities indicates the occurrence of the SR phenomenon. It is found that λ and τ play opposite role on the SR phenomenon, i.e., the SR is suppressed by increasing λ whereas it is enhanced with the increase of τ, which is different from the case where the periodic signal is additive. © 2010 Chinese Physical Society and IOP Publishing Ltd.

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