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Li J.,Hengyang Normal University | Kuang D.,Hengyang Normal University | Feng Y.,Hengyang Normal University | Zhang F.,Hengyang Normal University | And 2 more authors.
Journal of Hazardous Materials | Year: 2012

A graphene oxide (GO) film coated glassy carbon electrode (GCE) was fabricated for sensitive determination of 4-nitrophenol (4-NP). The GO-based sensor was characterized by scanning electron microscope, atomic force microscopy and electrochemical impedance spectroscopy. The electrochemical behaviors of 4-NP at the GO-film coated GCE were investigated in detail. In 0.1. M acetate buffer with a pH of 4.8, 4-NP yields a very sensitive and well-defined reduction peak at the GO-modified GCE. It is found that the GO film exhibits obvious electrocatalytic activity toward the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. Various kinetic parameters such as transfer electron number, transfer proton number and standard heterogeneous rate constant were calculated, and various experimental parameters were also optimized. Under the optimal conditions, the reduction peak current varies linearly with the concentration of 4-NP ranging from 0.1 to 120. μM, and the detection limit is 0.02. μM at the signal noise ratio of 3. Moreover, the fabricated sensor presented high selectivity and long-term stability. This electrochemical sensor was further applied to determine 4-NP in real water samples, and it showed great promise for simple, sensitive, and quantitative detection of 4-NP. © 2011 Elsevier B.V..


Liu M.,Hengyang Normal University | Luo C.,East China Normal University | Peng H.,East China Normal University
Talanta | Year: 2012

A polythiophene functionalized with methylene blue (PMT-MB) was synthesized and used as an indicator for electrochemical oligonucleotides (ODNs) hybridization detection. After hybridization with complementary ODNs, the current signal of PMT-MB increased, which illustrated that PMT-MB can effectively recognize complementary ODN targets as an indicator. Compared to MB, PMT-MB showed much better resistance to the concentration change of buffer solution. In all buffer solutions tested, the hybridization always resulted in the increased current signal of PMT-MB due to the electrostatic interaction. While, when MB was used as an indicator, the inconsistent current response was obtained after the hybridization. When high concentration of buffer solution was used for accumulation, the hybridization resulted in the decreased current signal, while at the low concentrations, the current signal increased. The interaction between PMT-MB and dsODNs was also studied by UV-vis spectroscopy. © 2011 Elsevier B.V. All rights reserved.


Chen Q.-C.,Hengyang Normal University
Chinese Physics B | Year: 2014

By using semiclassical theory combined with multiple-scale method, we analytically study the linear absorption and the nonlinear dynamical properties in a lifetime broadened L-type three-level self-assembled quantum dots. It is found that this system can exhibit the transparency, and the width of the transparency window becomes wider with the increase of control light field. Interestingly, a weak probe light beam can form spatial weak-light dark solitons. When it propagates along the axial direction, the soliton will transform into a steady spatial weak-light ring dark soltion. In addition, the stability of two-dimensional spatial optical solitons is testified numerically. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Deng P.,Hengyang Normal University | Xu Z.,Hengyang Normal University | Kuang Y.,Hengyang Normal University
Food Chemistry | Year: 2014

Herein, a novel electrochemical sensor based on an acetylene black paste electrode modified with molecularly imprinted chitosan-graphene composite film for sensitive and selective detection of bisphenol A (BPA) has been developed. Several important parameters controlling the performance of the sensor were investigated and optimised. The imprinted sensor offers a fast response and sensitive BPA quantification. Under the optimal conditions, a linear range from 8.0 nM to 1.0 μM and 1.0 to 20 μM for the detection of BPA was observed with the detection limit of 6.0 nM (S/N = 3). Meanwhile, the fabricated sensor showed excellent specific recognition to template molecule among the structural similarities and coexistence substances. Furthermore, this imprinted electrochemical sensor was successfully employed to detect BPA in plastic bottled drinking water and canned beverages. © 2014 Elsevier Ltd. All rights reserved.


Wang D.,Hengyang Normal University | Zhang F.,Hengyang Normal University | Kuang D.,Hengyang Normal University | Yu J.,Hengyang Normal University | Li J.,Hengyang Normal University
Green Chemistry | Year: 2012

6,7-Dihydroquinolin-8(5H)-one oxime (L3) was found to serve as a superior ligand for the CuI-catalyzed N-arylation of imidazoles with aryl iodides, bromides, and electron-deficient chlorides in water. Moreover, the CuI/L3 catalyst system enabled the coupling reactions to take place smoothly with high yields under a low catalyst loading (0.1-1 mol% CuI and 0.2-2 mol% L3). © 2012 The Royal Society of Chemistry.


Deng P.,Hengyang Normal University | Xu Z.,Hengyang Normal University | Li J.,Hengyang Normal University
Journal of Pharmaceutical and Biomedical Analysis | Year: 2013

In this paper, the simultaneous voltammetric determination of ascorbic acid (AA) and rutin (Ru) has been achieved at an acetylene black paste electrode modified with multi-walled carbon nanotubes-chitosan composite film (denoted as MWCNTs-CHIT/ABPE). Compared with bare electrode, the peak currents of AA and Ru at MWCNTs-CHIT/ABPE increased greatly and the anodic peak potential difference (ΔEpa) between AA and Ru are up to 342mV, which is undoubtedly attributed to the unique characteristics of AB and MWCNTs such as excellent electric conductivity, high surface area and strong adsorptive abilities, resulting in higher accumulation efficiency to AA and Ru. The influences of some experimental conditions on the oxidation of AA and Ru were tested and the calibration plot was examined. Under the optimized condition, a good linearity was obtained in the concentration range of 1μM-0.4mM for AA in the presence of 10μM Ru and 20nM-10μM for Ru in the presence of 1mM AA. The detection limits (S/N=3) of AA and Ru are 0.8μM and 10nM, respectively. The proposed method was successfully applied to the simultaneous determination of AA and Ru in pharmaceutical samples with reliable recovery. © 2013 Elsevier B.V.


Yang Z.,Hengyang Normal University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2015

In this paper, we consider initial-boundary value problem of Euler–Bernoulli viscoelastic equation with a delay term in the internal feedbacks. Namely, we study the following equation (Formula presented.) together with some suitable initial data and boundary conditions in Ω×(0,+∞). For arbitrary real numbers μ1 and μ2, we prove that the above-mentioned model has a unique global solution under suitable assumptions on the relaxation function g. Moreover, under some restrictions on μ1 and μ2, exponential decay results of the energy for the concerned problem are obtained via an appropriate Lyapunov function. © 2014, Springer Basel.


Jiang H.,Hengyang Normal University
Advances in Information Sciences and Service Sciences | Year: 2012

To aim the problem of document image segmentation, we propose a topic model based method to segment the document images into several areas, such as text, background, tables and figures. In the past, the segmentation of document images focused on threshold based method or supervised learning method. In our work, we firstly build a codebook by using PCA and K-means which only need an unsupervised learning method. Then, the document images are coded using codebook and the probability of each code is calculated using LDA based method, which is followed by a Markov random field, based labeling procedure. The advantage of proposed method include: unsupervised learning phase more reliable probability from LDA and smoothed segmentation results from MRF.


A method for increasing a detection sensitivity of a radon monitor based on an electrostatic collection method and a device thereof increase the detection sensitivity of the radon monitor based on the electrostatic collection method through increasing a collection efficiency of positively charged ^(218)Po in an internal cell of the radon monitor based on the electrostatic collection method. A metal mesh is provided between a wall of the internal cell and a semiconductor detector to increase an electric field intensity close to the wall of the internal cell. A ground wire of a high-voltage module is connected to a surface of the semiconductor detector. High-voltage outputting wires of the high-voltage module are respectively connected to the wall of the internal cell and the metal mesh, in such a manner that high voltages are respectively outputted between the wall of the internal cell and the metal mesh and between the metal mesh and the surface of the semiconductor detector. Because the electric field intensity close to the wall of the internal cell is increased through directly increasing the voltage between the wall of the internal cell and the metal mesh, once the voltages between the wall of the internal cell and the metal mesh and between the metal mesh and the surface of the semiconductor detector are adjusted to appropriate values, a collection efficiency of an electrostatic field to the positively charged ^(218)Po is increased.


A method and device for measuring radon by an electrostatic collection method without an influence of an environmental temperature and humidity is by reducing a pressure that in an electrostatic collection and measuring chamber to below a certain threshold value, in an operation temperature range of 0-45 degrees, and an air relative humidity of an external environment changing in 0%-100%, a collection efficiency of the collection and measuring chamber of the static electricity that collects positively charged ^(218)Po particle to a surface of a semiconductor detector is basically unchanged, so when a temperature and a humidity of the external environment change, a detection efficiency does not change; the threshold value relates to a geometric factor and a distribution of an electric field intensity that in different measuring chamber. The device comprises a measuring chamber, a semiconductor detector, a high-voltage module, a sampling pump, a vacuum gauge, and a regulating valve. The regulating valve is installed on an inlet pipe of the measuring chamber. The vacuum gauge and the sampling pump are installed on an outlet pipe of the measuring chamber. The semiconductor detector is installed inside an upper portion of the measuring chamber, and is connected to an interface port of the high-voltage module by a wire. Another interface port of the high-voltage module is connected to a shell of the measuring chamber by a wire.

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