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Changsha, China

Hunan University , located in Changsha, Hunan province, is one of the oldest and most important national universities in China. Wikipedia.

Lin Y.,Hunan University | Bao L.,East China University of Science and Technology | Wei Y.,Fudan University
IEEE Transactions on Automatic Control | Year: 2010

In this technical note, we investigate the numerical solution of the projected generalized Sylvester equations via a matrix sign function method. Such equations arise in stability analysis and control problems for descriptor systems including model reduction based on balanced truncation. Unlike the classical matrix sign function iteration, we propose a modification of the matrix sign function method that converges quadratically for pencils of arbitrary index. Numerical experiments report the effectiveness of the modified method. © 2006 IEEE.

Zhang H.,Hunan University | Jia X.,Wuhan University of Technology | Yu J.,Wuhan University of Technology | Xue L.,Wuhan University of Technology
Construction and Building Materials | Year: 2013

Organic expanded vermiculites (OEVMTs) were prepared using cetyltrimethyl ammonium bromide (CTAB) and octadecyl dimethyl benzyl ammonium chloride (ODBA) as intercalation agents. Effect of EVMT organic modification on physical and aging properties of styrene-butadiene-styrene (SBS) modified bitumen was investigated. The microstructures of the binders were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. EVMT/SBS modified bitumen forms a phase-separated structure, while OEVMT/SBS modified bitumens form the exfoliated nanostructures according to XRD analysis. OEVMTs show the more obvious influence on physical properties of SBS modified bitumen in comparison with EVMT. The compatibility between the EVMT and SBS modified bitumen is also improved after organic modification of EVMT. AFM analysis indicates that the contrast between the dispersed phase and the matrix phase in SBS modified bitumen increases with the addition of ODBA-EVMT. As a result of thin film oven test (TFOT), the viscosity aging index of SBS modified bitumen decreases, while the retained ductility and penetration increase obviously with the introduction of EVMT and OEVMTs. ODBA-EVMT/SBS modified bitumen has more pronounced improvements in aging resistance of SBS modified bitumen in comparison with CTAB-EVMT/SBS modified bitumen by preventing the phase-separated trend of the SBS modified bitumen during TFOT. © 2012 Elsevier Ltd. All rights reserved.

Guo Z.,Hunan University | Guo Z.,Chinese University of Hong Kong | Wang J.,Chinese University of Hong Kong | Yan Z.,Chinese University of Hong Kong
Neural Networks | Year: 2013

This paper addresses the global exponential dissipativity of memristor-based recurrent neural networks with time-varying delays. By constructing proper Lyapunov functionals and using M-matrix theory and LaSalle invariant principle, the sets of global exponentially dissipativity are characterized parametrically. It is proven herein that there are 22n2-n equilibria for an n-neuron memristor-based neural network and they are located in the derived globally attractive sets. It is also shown that memristor-based recurrent neural networks with time-varying delays are stabilizable at the origin of the state space by using a linear state feedback control law with appropriate gains. Finally, two numerical examples are discussed in detail to illustrate the characteristics of the results. © 2013 Elsevier Ltd.

Cao E.,Hunan University | Cao E.,University of Illinois at Urbana - Champaign
International Journal of Production Research | Year: 2014

This paper examines optimal decisions and coordination models for a dual-channel supply chain when the two end competition market demands are simultaneously disrupted. Firstly, we developed the pricing and production decisions models without demand disruptions and propose a revenue sharing contract to coordinate the dual-channel supply chain where the manufacturer is a Stackelberg leader and the retailer is a follower. We derived the conditions under which the maximum profit can be achieved in detailed. We compared the profits under normal case and disrupted case and quantified the information value of knowing demand disruptions. We proposed an improved revenue sharing contract to coordinate the dual-channel supply chain with demand disruptions. The results indicate that the adjusting prices and production quantity are the optimal decisions whether the demand disruptions case or normal case. We also find that the original revenue sharing contract is a special case of improved revenue sharing contract and the market scale change, channel substitutability and deviation cost affected the improved revenue sharing contract under demand disruptions. Finally, we further conduct numerical experiments to show how the demand disruption affects the decisions. © 2014 Taylor & Francis.

Li S.,Hunan University | Tan M.,Nanyang Technological University | Tsang I.W.,Nanyang Technological University | Kwok J.T.-Y.,Hong Kong University of Science and Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

Particle swarm optimizer (PSO) is a powerful optimization algorithm that has been applied to a variety of problems. It can, however, suffer from premature convergence and slow convergence rate. Motivated by these two problems, a hybrid global optimization strategy combining PSOs with a modified Broyden-Fletcher-Goldfarb-Shanno (BFGS) method is presented in this paper. The modified BFGS method is integrated into the context of the PSOs to improve the particles' local search ability. In addition, in conjunction with the territory technique, a reposition technique to maintain the diversity of particles is proposed to improve the global search ability of PSOs. One advantage of the hybrid strategy is that it can effectively find multiple local solutions or global solutions to the multimodal functions in a box-constrained space. Based on these local solutions, a reconstruction technique can be adopted to further estimate better solutions. The proposed method is compared with several recently developed optimization algorithms on a set of 20 standard benchmark problems. Experimental results demonstrate that the proposed approach can obtain high-quality solutions on multimodal function optimization problems. © 2011 IEEE.

Xu S.,Hunan University
Advanced Materials Research | Year: 2012

Since 2005 when Carbon Fund was formally introduced to China, the development of projects under the clean development mechanism(CDM) has experienced enormous growth, contributing to the sustainable development of industry. While there are at least two general barriers to get a balanced development of CDM projects in China - namely the limitation of implementation of CDM projects both in sector and scale spheres and problems faced by enterprises in development of CDM project - for assessment of the applicability of project methodology, this article compares the national Chinese registered projects and corresponding methodologies in the world. In the end, My analysis argues the underlying reasons and proposes several schemes to solve the problems. © (2012) Trans Tech Publications.

Wang K.,Hunan University
The Analyst | Year: 2013

Living cell studies can offer tremendous opportunities for biological and disease studies. Due to their high sensitivity and selectivity, minimum interference with living biological systems, ease of design and synthesis, fluorescent nucleic acid probes (FNAPs) have been widely used in living cell studies, such as for intracellular detection, cell detection, and cell-to-cell communication. Here, we review the general requirements and the recent developments in FNAPs for living cell studies. We broadly classify these designs as hybridization probes and aptamer probes. For hybridization probes, we describe recently developed designs, such as nanomaterial-based and amplification-based hybridization probes. For aptamer probes, we discuss four general paradigms that have appeared most frequently in the literature: nanomaterial-based, nanomachine-based, cell surface-anchored and activatable aptamer probe designs in vivo. FNAPs promise to open up new and exciting opportunities in biological marks detection for a wide range of biological and medical applications.

Wang M.-F.,Hunan University
International Journal for Numerical Methods in Biomedical Engineering | Year: 2011

On the basis of the applied loadings simulated by piecewise interpolation polynomials, a precise integration method using the Ritz vectors and a modified Krylov precise integration method are presented. The Ritz method is used to reduce the dimension of structural dynamic equations and the Krylov subspace method is applied to reduce the dimension of the exponential matrix required in the evaluation. The Padé approximation is employed in computing the initial matrices required for the recurrence evaluations of the exponential matrices of reduced size. The new cut-off criteria proposed in this paper are used to determine the required number of the Ritz vectors and the required size of the Krylov subspace. The accuracy of the time integration schemes presented is studied and compared with those of other commonly used schemes. The time integration schemes presented have arbitrary order of accuracy, wider application and are less time-consuming. Two numerical examples are also presented to demonstrate the applicability of the proposed methods. © 2010 John Wiley & Sons, Ltd.

Wiener A.,Imperial College London | Duan H.,Institute of Materials Research and Engineering of Singapore | Duan H.,Hunan University | Bosman M.,Institute of Materials Research and Engineering of Singapore | And 5 more authors.
ACS Nano | Year: 2013

We investigate the emergence of nonlocal effects in plasmonic nanostructures through electron-energy loss spectroscopy. To theoretically describe the spatial dispersion in the metal permittivity, we develop a full three-dimensional nonlocal hydrodynamic solution of Maxwell's equations in frequency domain that implements the electron beam as a line current source. We use our numerical approach to perform an exhaustive analysis of the impact of nonlocality in the plasmonic response of single triangular prisms and connected bowtie dimers. Our results demonstrate the complexity of the interplay between nonlocal and geometric effects taking place in these structures. We show the different sensitivities to both effects of the various plasmonic modes supported by these systems. Finally, we present an experimental electron-energy loss study on gold nanoprisms connected by bridges as narrow as 1.6 nm. The comparison with our theoretical predictions enables us to reveal in a phenomenological fashion the enhancement of absorption damping that occurs in these atomistic junctions due to quantum confinement and grain boundary electron scattering. © 2013 American Chemical Society.

Lei Y.,Hunan University | Murmu T.,University of Limerick | Adhikari S.,University of Swansea | Friswell M.I.,University of Swansea
European Journal of Mechanics, A/Solids | Year: 2013

The dynamic characteristics of damped viscoelastic nonlocal beams are studied in this paper. The Kelvin-Voigt and three-parameter standard viscoelastic models, velocity-dependent external damping and nonlocal Euler-Bernoulli beam theory are employed to establish the governing equations of motion for the bending vibration of nanobeams. A transfer function method (TFM) is developed to obtain closed-form and uniform solution for the vibration analysis of Euler-Bernoulli beams with different boundary conditions. New analytical expressions for critical viscoelastic parameters, damping parameters and limiting frequencies are obtained. Considering a carbon nanotube as a numerical example, the effects of the nonlocal and viscoelastic constants on the natural frequencies and damping factors are discussed. The results demonstrate the efficiency of the proposed modeling and analysis methods for free vibration analysis of viscoelastic damped nonlocal Euler-Bernoulli beams. © 2013 Elsevier Masson SAS. All rights reserved.

Yuan L.,Hunan University | Zuo Q.-P.,First Hospital of Changsha
Sensors and Actuators, B: Chemical | Year: 2014

Hydrogen sulfide (H2S) is now recognized as an important biological regulator and plays an important role in a vast number of physiological and pathological processes. However, understanding the important functions of H2S has remained challenging, in part due to the lack of tools for detecting endogenous H2S. Here, compound 2 was synthesized with one step reaction as a novel fluorescent turn-on probe for H2S on the basis of H2S-promoted thiolysis of dinitrophenyl ether. This free probe displayed almost no background signals due to both PET and ICT double signaling quenching mechanism. Thus, this probe shows large fluorescent turn-on and selectivity response to H2S and can be used for the fluorescence detection of both exogenous and endogenous H2S in cells with satisfactory sensitivity. Moreover, it was also applied for direct visualization of H2S in living tissues with two-photon microscopy. In addition to providing a highly sensitive and selective reaction-based fluorescent probe for H2S, the insights into the double signaling quenching mechanism controlling the signal-to-noise ratio of fluorescent turn-on probe may guide the design of fluorescent turn-on probes with better signal-to-noise ratio. © 2014 Elsevier B.V.

Zhu D.,Hunan University | Mobasher B.,Arizona State University | Vaidya A.,Arizona State University | Rajan S.D.,Arizona State University
Composites Science and Technology | Year: 2013

Woven fabrics are used in many applications, including ballistic armors, propulsion engine containment systems and fabric reinforced composites. In order to facilitate the design and improvement of such applications, this paper investigates the stress-strain response in warp and fill directions, the apparent Poisson's ratio, and the in-plane shear response of Kevlar 49 fabric including the possible effects of specimen size and pre-loading on the mechanical responses of the fabric. Full-field image analysis of the fabric under shear deformation is used to better understand the mechanisms related to in-plane shear. The experimental results show that the fabric exhibits non-linear and orthogonal behavior in tension, and can deform up to 20% before complete failure. It has identical Young's modulus (pre-peak elastic stiffness) in warp and fill directions, but has different crimp strain, tensile strength and ultimate strain. The apparent Poisson's ratio is a nonlinear function of strain and dependent upon the levels of pre-loading. It increases with strain quickly at the beginning and decreases gradually until the fabric fails. The shear response is highly nonlinear and has four distinct regions: linear elastic rotation region, dissipative rotation region, yarn compression region and shear locking region, and it is not dependent upon specimen size after normalization. © 2012 Elsevier Ltd.

Chen J.M.,Hunan University
Communications in Computer and Information Science | Year: 2012

This paper proposed an improved partition entropy coefficient (IPE) index by making using of the trend of partition entropy coefficient (PE) index to increase as the cluster number increases. Comparisons between IPE index and PE index and two existed cluster validity indexes are conducted on four real data sets. Experimental results show that IPE is able to identify the cluster number underlying the data set in the case that PE index is unable to do and outperforms the two existed cluster validity indexes. © Springer-Verlag Berlin Heidelberg 2012.

Peng J.,Zhengzhou University | Wang J.,Zhengzhou University | Wang Y.,Hunan University
Nonlinear Dynamics | Year: 2011

Abstract A novel robust hybrid tracking control for robotic system is proposed. This hybrid control scheme combines computed torque control (CTC) with neural network, variable structure control (VSC) and nonlinear H8 control methods. It is assumed that the nominal system of robotic system is completely known, which is controlled by using CTC method. Neural network is designed to approximate parameter uncertainties, VSC is used to eliminate the effect of approximation error, and H8 control is employed to achieve a desired robust tracking performance. Based on Lyapunov stability theorem, it can be guaranteed that all signals in closed loop are bounded and a specified H8 tracking performance is achieved by employing the proposed robust hybrid control. The validity of the control scheme is shown by computer simulation of a two-link robotic manipulator. © Springer Science+Business Media B.V. 2010.

In order to affirmatively utilize the characteristics of Hopf limit circle, a control method to design Hopf circle with proper characteristics into dynamical system is established based on the modified projective synchronization (MPS). The proposed method may serve as a complete solution to design a stable Hopf limit circle, which can simultaneously achieve the following three properties: with the desired amplitudes and shape changes, with the pre-specified location center, and at a pre-specified system parameter location. In contrast to the methods based on Hopf bifurcation theory, the new method is independent of the verbose procedures for the bifurcation critical conditions and the stability analysis. Numerical examples demonstrate the effectiveness of the proposed method. © 2010 Springer Science+Business Media B.V.

Tang Z.J.,Hunan University of Science and Technology | Zhan J.,Hunan University of Science and Technology | Liu H.L.,Hunan University
Electronics Letters | Year: 2012

A novel coplanar waveguide (CPW)-fed printed antenna with two asymmetric U-shaped strips is designed and analysed for ultra-wideband wireless applications. The asymmetric radiating structure with two U-shaped strips and a staircase-shaped strip is adopted in the proposed antenna which broadens the bandwidth to a great extent. The dimensions of the antenna are only 23×25.5×1.6mm. The antenna yields a wide bandwidth ranging from 3.0 to 12.9GHz with return loss less than -10dB with near-linear phase characteristics and stable antenna gain. Furthermore, the proposed antenna can achieve quasi-omnidirectional radiation patterns. The measured results agree well with the simulated prediction. © 2012 The Institution of Engineering and Technology.

Yin X.,Changsha University of Science and Technology | Fang Z.,Hunan University | Cai C.S.,Louisiana State University
Journal of Bridge Engineering | Year: 2011

When studying the vibration of a bridge-vehicle coupled system, most researchers focus on the vertical vibration of bridges under moving vehicular loads. In reality, the moving vehicular loads can also induce significant lateral vibrations of high-pier bridges. This study is focused on establishing a new methodology considering the bridge's lateral vibration induced by moving vehicles. The vehicle tire is modeled as a three-dimensional elementary spring model, and the contact patch is assumed to be a rectangle. Three significant factors that affect the lateral forces, including the slip angle, camber angle, and vehicle tires moving with an S shape, are introduced in studying the effect of the lateral forces on the lateral vibration of bridges. The bridge-vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact patch. The accuracy and efficiency of the present method are verified by comparing the simulations and the field test results of a typical high-pier bridge, showing that the proposed method can rationally simulate the lateral vibration of the bridge under moving vehicular loads. © 2011 American Society of Civil Engineers.

Zhang Y.-J.,Hunan University | Wang A.-D.,Beijing Institute of Technology | Da Y.-B.,Beijing Institute of Technology
Energy Policy | Year: 2014

It is an important task for China to allocate carbon emission quotas among regions so as to realize its carbon reduction targets and establish the national cap-and-trade carbon market. Meanwhile, it is supposed to be cost-effective to jointly reduce China's carbon emissions through some collaborative activities among regions. Then a natural question is how to allocate the quotas among regions in light of the collaboration. For this purpose, the Shapley value method is adopted and the results show that, first, the regions with higher GDP, higher carbon outflow and higher carbon reduction connection should be allocated more carbon quotas. Moreover, when the collaboration is considered, the optimal allocation of carbon quotas among regions will change significantly compared to the basic quotas by the entropy method; and the Central region is allocated the largest proportion of carbon quota among regions, which indicates its largest radiation effect. Besides, the collaboration between the Central region and Northern coast region, and that between the Central region and the Eastern region should be paid close attention. These results may provide insightful support for decision makers to promote collaborative carbon reduction and allocate carbon quotas in China. © 2014 Elsevier Ltd.

Yuan S.,Wuyi University | Liao A.,Hunan University
Journal of the Franklin Institute | Year: 2014

In this paper, a new method is presented to solve the least squares Hermitian problem of the complex matrix equation AXB +CXD =E . The explicit expression of least squares Hermitian solution with the least norm is given. The least squares Hermitian solution with the least norm of complex matrix equation AXB =E is also derived. Numerical algorithms and numerical examples show the feasibility of our method. © 2014 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

Luo D.,University of Malaya | Ibrahim Z.,University of Malaya | Ismail Z.,University of Malaya | Xu B.,Hunan University
Computer-Aided Civil and Infrastructure Engineering | Year: 2013

In this article, a geometrical optimization procedure using biconical tapered fiber sensors is proposed for monitoring the early-age curing temperatures of concrete specimens. The geometries of the sensors are theoretically optimized by the ray-tracing theory. The results of the theoretical analysis show that the performance of the sensors is heavily influenced by Evanescent Waves, which are due to the tunneling rays and are fully escaped by tapering the fiber. The effects of the geometrical parameters, including the taper ratios, taper lengths, and ray launch angles, as well as the surrounding temperatures, on the behavior of the sensors are studied numerically. The numerical results demonstrate that higher performance of the proposed optimized sensors can be achieved by a longer taper length and smaller taper ratio combined with an initial ray launching angle of 0.01 rad. An experimental study on early-age curing temperature monitoring of concrete specimens with the biconical tapered fiber sensors was carried out. The experimental measurements agree well with the theoretical results. © 2013 Computer-Aided Civil and Infrastructure Engineering.

Hu X.-M.,Hunan University
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2010

This paper analyzes the formation, failure mechanism and mechanical properties of the transition layer. And it points out that the interface separation, base layer vertical cracking and surface layer invaded by base layer interface horizontal crack are the three kinds of basic forms of the transition layer failure. The experimental results show that: the transition layer attached on surface layer will decrease the flexural tensile strength and fatigue property of the surface layer concrete; the flexural tensile strength is decreased 0.2~0.4 MPa, trabecular flexural fatigue life is decreased one or two order of magnitudes; setting isolation layer to prevent cement slurry from entering basic layer on the surface of basic layer can effectively prevent the formation of the transition layer thus avoid it from the three kinds of failure modes on pavement structure induced by the transition layer.

Gui R.,Shanghai JiaoTong University | Wan A.,Shanghai JiaoTong University | Liu X.,Hunan University | Yuan W.,Michigan State University | Jin H.,Shanghai JiaoTong University
Nanoscale | Year: 2014

Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4·H 2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in the bright fluorescent QDs with high PL quantum yields (QYs: 14.2-16.4%). Experimental results confirm that the QDs have high PL stability and ultralow cytotoxicity, as well as high PLQYs and small hydrodynamic sizes (4.5-5.6 nm) similar to fluorescent proteins (27-30 kDa), indicating the feasibility of highly effective PL imaging in cells and living animals. This journal is © the Partner Organisations 2014.

Jiang T.-Y.,Changsha University of Science and Technology | Fang Z.,Hunan University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2011

Aimed at anchorage problems that carbon fiber reinforced polymer/plastics (CFRP) was used as prestress tendon and cable reactive powder concrete (RPC) was regarded as bond medium and based on it, a new bond-type anchorage was developed. The calculated formulas of average bond strength and its corresponding slip, critical anchorage length, and bond-slip constitutive model were proposed. Influences of surface shape, bond length, number and space of CFRP tendons, slope angle of inner wall of steel sleeve and pretensioning load on anchorage performance were studied by static test. Test results show that the surface shape of CFRP tendon is significant to the anchorage performance of the bond-type anchorage. When the tensile strength of the indented surface CFRP tendon is less than 3000 MPa and compressive strength of RPC is more than 130 MPa, the critical anchorage length is 20 diameters of general CFRP tendon for common bond specimen, the shortest critical anchorage length in anchorage system is 13 diameters of pretensioning CFRP tendon with ratio of 56% of pretensioning load. The appropriate rod space is not less than rod diameter for the anchorage system with multiple CFRP tendons.

Gui R.,Shanghai JiaoTong University | Wan A.,Shanghai JiaoTong University | Liu X.,Hunan University | Jin H.,Shanghai JiaoTong University
Chemical Communications | Year: 2014

Gold nanoclusters and doxorubicin dual-loaded liposomes were prepared by using a supercritical CO2 method, and developed toward intracellular fluorescent thermometry, photothermal-triggered drug release and tumor therapy. This journal is © The Royal Society of Chemistry.

Lu B.,Hunan mechanical and electrical polytechnic | Huang W.,Hunan University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2011

This paper proposes a novel hybrid wavelet-energy operator method for accurate voltage sag detection and measurement. In the proposed method, the voltage sag is decomposed into two signal parts by wavelet transform: one is a detail signal, the other is an approximation signal. And in the detail signal, the start time and the end time of the sag signal can be detected. By applying an energy operator to the approximation signal, the temporary sag decline in value can be measured accurately and quickly. At the same time, the wavelet transform (WT) in this method acts like a filter. WT can weaken or remove the high frequency disturbance from voltage sag to enhance the noise immunity and accuracy of the energy operator. Simulation and experimental results verify the effectiveness of the algorithm.

Xu Y.,Hunan University | Chan E.H.W.,Hong Kong Polytechnic University
Journal of Urban Planning and Development | Year: 2012

The community question, referring to the transformation of social networks when rural residents move into urban areas, has been extensively debated by urbanists and sociologists in Western countries. This paper, focusing on the urbanization of rural villages caused by urban expansion and land requisition, examines the community question in the context of transitional China. It aims to investigate whether the unique institutional settings in China will lead to a different answer to the community question. Compared with the existing studies, there are two improvements in the design of this research, which include: (1) adding a middle stage to divide the urbanization process into the three stages of rural village, semiurbanization village, and urban resettlement housing district, thereby identifying and comparing the status of personal social ties at each stage of the state-led urbanization process; and (2) controlling the features of sampled villages and characteristics of respondents that may affect social life patterns, therefore understanding the exact effects of urbanization on neighborhood social life. This study found that (1) the conventional community- lost argument finds support in transitional China with state-led urbanization; (2) the decline of social ties is nonlinear during the urbanization process, which is different from the common statement of linear transformation in the literature. Instead, the decline reaches the lowest point at the stage of semiurbanized village; and (3) the structure of personal networks also changes along with the process of community lost. © 2011 American Society of Civil Engineers.

Chen Z.-Q.,Hunan University
Gongcheng Lixue/Engineering Mechanics | Year: 2014

The geometrically nonlinear finite element method for beam structures consists of two parts: the development of virtual work equations and the corresponding numerical implementation. In this study, the solution procedure of the geometrically nonlinear finite element analysis using the Updated Lagrangian (UL) incremental approach for beam structures and three-dimensional continuum is presented, and major differences in the solution process are identified. Particularly, emphasis has been placed on the importance and the methodology of determining internal forces at the end of each load step.

Li L.,Hunan University
International Journal of Online Engineering | Year: 2016

Nowadays, Radio frequency identification (RFID) has been extensively deployed to retailing, supply chain management, object recognition, object monitoring and tracking and many other fields. Detecting outliers in RFID data streams can help us find abnormal activities and thus avoid disasters. In order to detect outliers in RFID data streams efficiently and effectively, we proposed a fractal based outlier detection algorithm. Firstly, we built a monotone searching space based on the self-similarity of fractal. Then, we proposed two piecewise fractal models for RFID data streams, and presented an outlier detection algorithm based on the piecewise fractal model. Finally, we validated the efficiency and effectiveness of the proposed algorithm by massive experiments.

Yang J.,Hunan Institute of Engineering | Hu W.,Hunan University | Tang J.,Hunan Agricultural University
RSC Advances | Year: 2014

The impact deposition of Al (or Fe) atoms on the rhombohedron of Fe (or the truncated octahedron of Al) nanoparticles is investigated by performing a molecular dynamics simulation using the embedded atom method. These simulations are performed in different incident energies (from 10 eV to 50 eV). The dependence of the incident energy of deposited atoms on the growth configurations of Fe-Al nanoparticles is analyzed. For the deposition of Al atoms on the Fe nanoparticle, some Al atoms are incorporated into the Fe core as the incident energy of Al increases. A nanoparticle configuration with Fe-core and Al-shell is usually observed at all incident energies considered. In this case, the substrate Fe atoms and the deposited Al atoms are arranged in body-centered cubic configuration. For the impact deposition of Fe atoms on the Al nanoparticle, an onion-like nanoparticle is observed at incident energy of 10 eV. A configuration with Al-shell and alloyed Fe-Al core is obtained as the incident energy increases. This study proposes a method of artificially controlling nanoalloy configuration. © 2014 The Royal Society of Chemistry.

Yin J.,Norwegian University of Science and Technology | Yin J.,Hunan University | Yang J.,Chalmers University of Technology | Pantaleev M.,Chalmers University of Technology | Helldner L.,Chalmers University of Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

Future ultra-wideband (UWB) radio telescopes require UWB feeds for reflector antennas, and many new UWB feed technologies have gained substantial progress to satisfy the tough specifications for future radio telescope projects, such as the square kilometer array (SKA). It has been noticed that, different from traditional narrow-band horn feeds, all UWB feeds are non-BOR (Body of Revolution) antennas. Therefore, BOR1 efficiency becomes an important characterization for the modern UWB feed technologies. We present a novel circular Eleven feed, constructed of 'circularly' curved folded dipoles printed on flat circuit boards, in order to have high BOR1 efficiency at a low manufacture cost. The Genetic Algorithm (GA) optimization scheme has been applied to the design for achieving a low reflection coefficient. Simulated and measured results show that the circular Eleven feed has a reflection coefficient below-6 dB over 1.6-14 GHz and below-10 dB over 78% of the band, and an aperture efficiency higher than 60% over 1-10 GHz and 50% up to 14 GHz. © 2013 IEEE.

Li H.,Hunan University | Lei J.,North China Electrical Power University | Liu Q.,CAS Institute of Engineering Thermophysics
International Journal of Heat and Mass Transfer | Year: 2012

The inverse heat conduction problems (IHCP) analysis method provides an efficient approach for estimating the thermophysical properties of materials, the boundary conditions, or the initial conditions. Successful applications of the IHCP method depend mainly on the efficiency of the inversion algorithms. In this paper, a generalized objective functional, which has been developed using a generalized stabilizing functional and a combinational estimation that integrates the advantages of the least trimmed squares (LTS) estimation and the M-estimation, is proposed. The objective functional unifies the regularized M-estimation, the regularized least squares (LS) estimation, the regularized LTS estimation, the regularized combinational estimation of the LTS estimation and the M-estimation, and the regularized combinational estimation of the LS estimation and the M-estimation into a concise formula. The filled function method, which is coupled with the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm, is developed for searching a possible global optimal solution. Numerical simulations are implemented to evaluate the feasibility and effectiveness of the proposed algorithm. Favorable numerical performances and satisfactory results are observed, which indicates that the proposed algorithm is successful in solving the IHCP. © 2012 Elsevier Ltd. All rights reserved.

Long M.,Changsha University of Science and Technology | Chen Y.,University of Warwick | Peng F.,Hunan University
IEEE Communications Letters | Year: 2011

A simple yet accurate analysis of the bit error rate performance for differential chaos shift keying communication system is proposed for an additive white Gaussian noise channel by using the non-central F distribution of the decision variable and assuming variable bit energy in the calculation. The new method has much higher accuracy or much lower computational complexity than the existing methods in the literature. Numerical results show that in most cases, the predicted bit error rate from the new method is indistinguishable from the simulated bit error rate, showing the effectiveness of our result. © 2011 IEEE.

Li Q.,Chinese University of Hong Kong | Zhang C.,Chinese University of Hong Kong | Ma J.,Hunan University | Wang G.,CAS Hefei Institutes of Physical Science | Ng D.H.L.,Chinese University of Hong Kong
ChemCatChem | Year: 2014

The ultra-small Ag nanocrystallite-decorated TiO2 hollow sphere heterostructures were fabricated by using a two-step hydrothermal method. These heterostructures demonstrated an excellent photodegradation performance of rhodamine B. The photodegradation efficiency could reach up to 100 % within 20 min under simulated sunlight irradiation. XRD, field emission SEM, TEM, scanning TEM, high-resolution TEM coupled with energy-dispersive X-ray spectroscopy, UV/Vis absorption and photoluminescence spectroscopy, X-ray photoelectron spectroscopy, Mott-Schottky analysis, and hydroxyl radical measurements were used to correlate the structure, surface property, and energy band alignment of rhodamine B to its photocatalytic activity. In these metal-semiconductor heterostructures, the Ag nanocrystallites were highly crystalline and were distributed evenly on the surface of TiO2 hollow spheres with compact interfaces. They reduced the recombination rate of charge carriers and favoured the charge transfer across the interfaces. The increased surface adsorbed oxygen facilitated the generation of hydroxyl radicals, and the reduced surface defects increased the lifetime of charge carriers upon Ag loading. The Schottky barriers between Ag and illuminated TiO2, the upward shift of the Fermi level, and increased electron density due to Ag coupling contributed to the charge transfer and increase in quantum efficiency. These key factors involved in photocatalysis are of great importance to design functional and effective photocatalysts. Hollow, Hollow, Hollow: Ag-TiO2 hollow sphere heterostructures demonstrate an excellent photodegradation efficiency of rhodamine B under simulated sunlight irradiation owing to the excellent dispersion of Ag nanocrystallites, increase in surface adsorbed oxygen, and increased lifetime of charge carriers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang W.L.,Hunan University
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi | Year: 2012

To elucidate the genetic diversifications of avian influenza subtype H5N1 viruses in the boundary regions of Yunnan province during 2009 to July, 2011. Swab samples were collected from foreign poultry and wild birds in boundary regions of Yunnan province during 2009 to July, 2011 and tested by H5/N1 subtype-specific multiplex RT-PCR. The HA genes of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. Both alignment and phylogenetic analysis were performed with sequences of the known reference strains. Fifteen different HA sequences were obtained from 36 representative positive samples and could be divided into 2 distinct Clades (2.3.2 and 2.3.4). Through phylogenetic analysis, Clade 2.3.2 and 2.3.4 could then be further divided into 3 (II-1 to II-3) and 2 smaller clades (I-1 and I-2), respectively. The viruses of Clade 2.3.2 II-1 and II-2 were new variant strains of H5N1 virus. The cleavage sites of HA from positive samples all possessed molecular characterization of highly pathogenic avian influenza virus. Mutation of key amino acids had been found among receptor binding sites, potential glycosylation sites, neutralizing epitopes and others. It seemed evident that the H5N1 subtype viruses showed genetic diversifications and had undergone the evolution progress of multi-clade (2.3.2, 2.3.4) to single calde (2.3.2) in the boundary regions of Yunnan province, during 2009 to July, 2011.

Li X.,Central South University | Su Y.,Hunan University
Structural Safety | Year: 2016

Applications of the reliability-based method to stability evaluation of tunnel structures have become an ever-increasing concern over recent years. One critical challenge in conducting such a task is the implicit nature of the limit state function (LSF). To address this issue, the focus of this study is on, among others, the use of response surface method (RSM) by considering both the selection of the sampling method and the choice of the response surface form (as two major factors affecting the RSM's performance). In this context, the current paper develops for tunnel-reliability analysis a hybrid approach combing an experimental design called uniform design (UD) and a regression device known as support vector machine (SVM). For the proposed hybrid approach, the UD is used to generate sampling points and then the SVM is employed to construct the response surface approximating the original inexplicit LSF. Such an approach integrates the merits of both UD and SVM used for complex nonlinear modelling. Three carefully selected tunnel examples are illustrated: one for a typical tunnel under relatively simplified tunnelling conditions and the other two for real-life tunnels. Comparisons are made to validate the computational accuracy and efficiency of the present approach. In particular, for the tunnel example where the LSF is known only implicitly through the numerical analyses (which is the scenario of many real-world applications in tunnel community), the obtained results further demonstrate the efficiency of this approach: it can be much more economical to achieve reasonable accuracy than the conventional RSMs when a small number of sampling data is used. Such comparisons made in this work verify the application potential of the developed hybrid approach for probabilistic tunnel stability assessment involving the implicit LSF. © 2016 Elsevier Ltd.

Liu M.R.,Hunan University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2012

To observe the effect of acupuncture of "Zusanli" (ST 36) and "Taichong" (LR 3) on gastrointestinal hormone levels in diarrhea type irritable bowel syndrome (IBS-D) rats so as to provide experimental evidence for acupuncture treatment of IBS-D. Forty-eight Wistar rats were randomly divided into control, model, acupuncture and medication groups, with 12 rats in each group. IBS-D model was established by chronic mild restraining stress combined with isolated raising and intragastric administration of Folium Sennae (10 mL/kg). For rats of the acupuncture group, bilateral "Zusanli" (ST 36) and "Taichong" (LR 3) were punctured and stimulated for 30 min, once daily for 14 days. The rats of the medication group were treated by gavage of Pinaverin bromide, once daily for 14 days, and those of the control and model groups were given with equal volume of saline. Somatostatin (SS), substance P (SP) and vasoactive intestinal peptide (VIP) in the rats' plasma and ileum tissues were detected by sandwich enzyme-linked immunosorbent assay (ELISA). Compared with the control group, the body weight and food intake quantity were reduced significantly, while the diarrhea index was increased significantly in the model group (P < 0.05, P < 0.01). In comparison with the model group, the body weight and food intake volume in both acupuncture and medication groups were increased remarkably after the treatment (P < 0.05, P < 0.01) whereas the diarrhea index in the latter two groups was reduced obviously (P < 0.01). Compared with the control group, plasma VIP level was increased significantly in the model group (P < 0.01), while those in both acupuncture and medication groups were decreased remarkably compared with the model group (P < 0.05). No significant changes of plasma SP and SS levels were found after modeling and after both acupuncture and medication treatments. In comparison with the control group, ileum SP, VIP and SS levels in the model group were up-regulated significantly (P < 0.01), while those in both acupuncture and medication groups were down-regulated considerably compared with the model group (P < 0.01). No significant differences were found between acupuncture and medication groups in the levels of ileum SP, VIP and SS (P > 0.05). Acupuncture of ST 36 and LR 3 can effectively down-regulate ileum SP, VIP and SS levels in IBS-D rats, which may contribute to its effect in relieving IBS-D.

Zhang Z.,Hunan University | Zhou D.,Yunnan University
Neural Networks | Year: 2012

In this paper, we first discuss the existence of a unique equilibrium point of a generalized Cohen-Grossberg BAM neural networks of neutral type delays by means of the Homeomorphism theory and inequality technique. Then, by applying the existence result of an equilibrium point and constructing a Lyapunov functional, we study the global asymptotic stability of the equilibrium solution to the above Cohen-Grossberg BAM neural networks of neutral type. In our results, the hypothesis for boundedness in the existing paper, which discussed Cohen-Grossberg neural networks of neutral type on the activation functions, are removed. Finally, we give an example to demonstrate the validity of our global asymptotic stability result for the above neural networks. © 2011 Elsevier Ltd.

Zhang X.-P.,Hunan University
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2012

The c plane sapphire with size of φ170 mm×160 mm, weight of 12 kg was grown by heat-exchange method. The crystal is transparent, and no particle/bubble in the crystal. According to the interference figure, the fringes are distorted in the center of the crystal because of the stress. After the chemical etching, the triangular etch pits appears through the microscope, and the etch pits density is low, just 1.98×10 3 Pits/cm 2. The FWHM is so narrow, the crystal quality is good.

Liu Q.H.,Hunan University
Journal of the Physical Society of Japan | Year: 2013

As a manifold is embedded into a higher dimensional Euclidean space, quantum mechanics gives various embedding quantities. In the present study, two embedding quantities for a two-dimensional curved surface in the threedimensional flat space, the geometric momentum and the geometric potential, are derived in a unified manner. For a particle moving on a two-dimensional sphere or a free rotation of a spherical top, the projections of both the geometric momentum p and the angular momentum L onto a certain Cartesian axis form a complete set of commuting observables as [pi; Li] = 0 (i = 1; 2; 3), thus constituting a dynamical [pi; Li] representation for the states on the twodimensional spherical surface. The geometric momentum distribution of the states represented by spherical harmonics is successfully obtained, and this distribution for a homonuclear diatomic molecule seems within the resolution power of present momentum spectrometers and can be measured to probe the embedding effect. © 2013 The Physical Society of Japan.

Xiao Y.,Hunan University | Xiao Y.,University of Southern California | Ma J.,Zhejiang Prov Institute Of Architectural Design And Research
Construction and Building Materials | Year: 2012

A fire simulation experiment of a full-scale room unit model was carried out to study the fire safety of lightweight glue-laminated bamboo (glubam) frame buildings. Wooden crib with its quantity determined based on typical fire load intensity for residential buildings was stacked and ignited in the experimental room unit. The test was finished after 1 h. Temperature histories of several points on walls and upper floor slab, fire behavior of the over-all structure and the damage to the members were examined. Numerical simulation was conducted using fire-driven fluid dynamics software Fire Dynamics Simulator (FDS) developed by National Institute of Standards and Technology (NIST). The simulated results were compared with the experimental observations, demonstrating that the FDS is a useful tool to provide visual simulation of the experimental testing. Fire design measures using gypsum boards and rock wool insulation suggested for the new bamboo building are found adequate from this research. © 2012 Elsevier Ltd. All rights reserved.

Fang X.,CAS Beijing National Laboratory for Molecular | Tan W.,University of Florida | Tan W.,Hunan University
Accounts of Chemical Research | Year: 2010

Molecular medicine is an emerging field focused on understanding the molecular basis of diseases and translating this information into strategies for diagnosis and therapy. This approach could lead to personalized medical treatments. Currently, our ability to understand human diseases at the molecular level is limited by the lack of molecular tools to identify and characterize the distinct molecular features of the disease state, especially for diseases such as cancer. Among the new tools being developed by researchers including chemists, engineers, and other scientists is a new class of nucleic acid probes called aptamers, which are ssDNA/RNA molecules selected to target a wide range of molecules and even cells. In this Account, we will focus on the use of aptamers, generated from cell-based selections, as a novel molecular tool for cancer research. Cancers originate from mutations of human genes. These genetic alterations result in molecular changes to diseased cells, which, in turn, lead to changes in cell morphology and physiology. For decades, clinicians have diagnosed cancers primarily based on the morphology of tumor cells or tissues. However, this method does not always give an accurate diagnosis and does not allow clinicians to effectively assess the complex molecular alterations that are predictive of cancer progression. As genomics and proteomics do not yet allow a full access to this molecular knowledge, aptamer probes represent one effective and practical avenue toward this goal. One special feature of aptamers is that we can isolate them by selection against cancer cells without prior knowledge of the number and arrangement of proteins on the cellular surface. These probes can identify molecular differences between normal and tumor cells and can discriminate among tumor cells of different classifications, at different disease stages, or from different patients. This Account summarizes our recent efforts to develop aptamers through cell-SELEX for the study of cancer and apply those aptamers in cancer diagnosis and therapy. We first discuss how we select aptamers against live cancer cells. We then describe uses of these aptamers. Aptamers can serve as agents for molecular profiling of spedfic cancer types. They can also be used to modify therapeutic reagents to develop targeted cancer therapies. Aptamers are also aiding the discovery of new cancer biomarkers through the recognition of membrane protdn targets. Importantly, we demonstrate how molecular assemblies can integrate the properties of aptamers and, for example, nanoparticles or microfluidic devices, to improve cancer cell enrichment, detection and therapy. Figure Presented. © 2010 American Chemical Society.

Zhang Z.,Hunan Institute of Science and Technology | Xia F.-L.,Hunan University | Li X.-P.,Hunan Institute of Science and Technology
Pramana - Journal of Physics | Year: 2013

In this paper, we investigate the bifurcations and dynamic behaviour of travelling wave solutions of the Klein-Gordon-Zakharov equations given in Shang et al, Comput. Math. Appl. 56, 1441 (2008). Under different parameter conditions, we obtain some exact explicit parametric representations of travelling wave solutions by using the bifurcation method (Feng et al, Appl. Math. Comput. 189, 271 (2007); Li et al, Appl. Math. Comput. 175, 61 (2006)). © Indian Academy of Sciences.

Hu G.,University of Northern British Columbia | Li J.,University of Northern British Columbia | Zeng G.,Hunan University
Journal of Hazardous Materials | Year: 2013

Oily sludge is one of the most significant solid wastes generated in the petroleum industry. It is a complex emulsion of various petroleum hydrocarbons (PHCs), water, heavy metals, and solid particles. Due to its hazardous nature and increased generation quantities around the world, the effective treatment of oily sludge has attracted widespread attention. In this review, the origin, characteristics, and environmental impacts of oily sludge were introduced. Many methods have been investigated for dealing with PHCs in oily sludge either through oil recovery or sludge disposal, but little attention has been paid to handle its various heavy metals. These methods were discussed by dividing them into oil recovery and sludge disposal approaches. It was recognized that no single specific process can be considered as a panacea since each method is associated with different advantages and limitations. Future efforts should focus on the improvement of current technologies and the combination of oil recovery with sludge disposal in order to comply with both resource reuse recommendations and environmental regulations. The comprehensive examination of oily sludge treatment methods will help researchers and practitioners to have a good understanding of both recent developments and future research directions. © 2013 Elsevier B.V.

Cao Y.,Hunan University | Wang G.,Jinhua Electrical Power Bureau
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

The power system complexity and its related research progress are introduced in terms of existence and evolution, and the relationship between existence complexity and evolution complexity is analyzed. The existence complexity contains the multilayer & inter-relevancy, nonlinear dynamics, randomness, real-time, social economics, openness, etc., and the evolution complexity contains the self-organization, synergetics, mutagenicity, and fractal dimension, etc. The theoretical framework of power system complexity study is proposed, including its basic concept, its comprehensive analysis method and system, the power system self -organized criticality, the power system network features, the simulation and prediction methods of power system cascading failures based on the complexity theory, its comprehensive integration technology, etc. The important topics and future work related to the research of power system complexity are pointed out.

Wang C.,Hunan University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2010

OBJECTIVE: To observe the effect of electroacupuncture (EA) on contents of myocardial nitric oxide (NO), nitric oxide synthase (NOS), and intracellular Ca2+ levels in experimental myocardial ischemia-reperfusion injury (MI/RI) rats, so as to provide some evidence for acupuncture treatment of cardiovascular disorders and for the correlation between the acupoints and the internal organs. METHODS: Fifty male Wistar rats were randomly divided into sham-operation (sham), model, Neiguan (PC 6), Lieque (LU 7), and Hegu (LI 4) groups (n = 10/group). MI/RI model was established by occlusion of the descending anterior branch of the left coronary artery for 40 min and reperfusion for 60 min. EA (30 Hz/100 Hz, 2-4 mA) was applied to the bilateral PC 6, LU 7 and LI 4 for 20 min. The myocardial tissue of the ischemic area was taken, homogenated and centrifuged, separated for assaying NO and NOS activity by using spectrophotometer and their contents with nitrate reductase colorimetric assay. Another part of the myocardium tissue was processed to be cell suspension (added with Fluo-3/AM dye) for assaying intracellular free [Ca2+]i concentration under the laser confocal microscope. RESULTS: Compared with sham group, myocardial NO and NOS contents of model group decreased mildly and significantly (P < 0.05), while myocardial fluorescence intensity (content) of intracellular Ca2+ increased evidently (P < 0.01). In comparison with model group, the contents of myocardial NO and NOS were upregulated considerably in PC 6 group (P < 0.05), and intracellular Ca2+ content in PC 6 group reduced significantly (P < 0.01). No significant differences were found between LU 7 and model groups and between LI 4 and model groups in the above mentioned 3 indexes (P > 0.05). CONCLUSION: EA of PC 6 can upregulate myocardial NO and NOS contents and downregulate myocardial intracellular Ca2+ level in MI/RI rats, which may contribute to its effect in relieving myocardial injury. Neiguan (PC 6) and the heart have a relatively specific correlation.

Metoprolol (MET) is a β1-adrenoceptor antagonist, which is widely used in the treatment of cardiovascular diseases, and α-hydroxymetoprolol (α-OHM) is its hydroxylated metabolite. Owing to their similar structures, optimization of the condition for the chromatography approach, which is in common use for determination, is both time consuming and laborious. A new and effective strategy that combines the excitation-emission matrix fluorescence with second-order calibration methods was developed for simultaneous determination of MET and α-OHM in human plasma. Although the fluorescence spectra of MET and α-OHM overlapped and a large number of unknown and uncalibrated fluorescent components coexisted, the developed method enables accurate concentrations together with reasonable resolution of excitation and emission profiles for the analytes of interest. An additional advantage of the proposed method is that there is no need for separation and sample pretreatment, in addition to lower cost than traditional methods.

Liu Z.,Henan University of Technology | Wang Z.,Henan University of Technology | Cao Y.,Henan University of Technology | Jing Y.,Henan University of Technology | Liu Y.,Hunan University
Sensors and Actuators, B: Chemical | Year: 2011

A novel nanocomposite, comprising of graphene sheet (GS) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), was developed on the glassy carbon electrode (GCE) for the simultaneous determination of hydroquinone and catechol in 0.10 M acetate buffer solution (pH 5.0). At the GS/BMIMPF6/GCE, both hydroquinone and catechol can cause a pair of quasi-reversible and well-defined redox peaks. In comparison with bare GCE and GS modified electrode, GS/BMIMPF6/GCE showed larger peak currents, which was related to the higher specific surface area of graphene and high ionic conductivity of BMIMPF6. Under the optimized condition, the cathodic peak current were linear over ranges from 5.0 × 10-7 M to 5.0 × 10-5 M for hydroquinone and from 5.0 × 10-7 M to 5.0 × 10-5 M for catechol, with the detection limits of 1.0 × 10-8 M and 2.0 × 10 -8 M, respectively. The proposed method was successfully applied to the simultaneous determination of hydroquinone and catechol in artificial sample, and the results are satisfactory. © 2011 Elsevier B.V.

In order to improve the performance of air source heat pump in cold climate region, a combined oil flooded compression with regenerator and vapor injection cycle system is suggested in this paper, which integrates oil flooded compression with regenerator into a conventional vapor injection cycle. A mathematical model is developed and parametric studies on this cycle are conducted to evaluate the benefits of the novel system. The performances of the novel system using R410A and R32 are compared with those of vapor injection cycle system. The improvement of coefficient of performance (COP) can reach up to nearly 9% based on the same isentropic efficiency, while 17.2% based on assumption that there is a 10% rise in isentropic efficiency brought by oil flooded compression cycle. The heating capacity is reduced by 8-18% based on the same volumetric efficiency, while could be less than 10% in a practical system. The discharge temperature is largely decreased and can be below 100°C at -40°C Te and 50°C Tc condition for R32. The theoretical results demonstrate this novel heat pump has a high potential for improving the performance of air source heat pump in cold climate region. © 2016 Elsevier Ltd. All rights reserved.

Ke S.,Hunan University | Feser E.,University of Illinois at Urbana - Champaign
Regional Studies | Year: 2010

KE S. and FESER E. Count on the growth-pole strategy for regional economic growth? Spread-backwash effects in Greater Central China. Regional Studies. This paper investigates spread-backwash effects associated with non-agricultural gross domestic product and employment growth across 922 cities and counties in Central China between 2000 and 2005. Simultaneous equation estimates find mixed spread-backwash effects from prefecture and higher-level cities to comparable or lower-level cities and counties. Spread effects of gross domestic product and employment growths are also indicated between county-level cities. However, county-level cities exerted backwash effects on rural counties. The paper discusses the implications of these findings in relation to the construction of urban economic growth zones in Central China as an important strategy of Central Rise. © 2010 Regional Studies Association.

Jin G.,University of Waterloo | Jin G.,National University of Defense Technology | Matthews D.E.,University of Waterloo | Zhou Z.,Hunan University
Reliability Engineering and System Safety | Year: 2013

The paper presents a Bayesian framework consisting of off-line population degradation modeling and on-line degradation assessment and residual life prediction for secondary batteries in the field. We use a Wiener process with random drift, diffusion coefficient and measurement error to characterize the off-line population degradation of secondary battery capacity, thereby capturing several sources of uncertainty including unit-to-unit variation, time uncertainty and stochastic correlation. Via maximum likelihood, and using observed capacity data with unknown measurement error, we estimate the parameters in this off-line population model. To achieve the requirements for on-line degradation assessment and residual life prediction, we exploit a particle filter-based state and static parameter joint estimation method, by which the posterior degradation model is updated iteratively and the degradation state of an individual battery is estimated at the same time. A case study of some Li-ion type secondary batteries not only shows the effectiveness of our method, but also provides some useful insights regarding the necessity of on-line updating and the apparent differences between the population and individual unit degradation modeling and assessment problems. © 2012 Elsevier Ltd.

Response surface methodology along with Box-Behnken design was firstly applied to optimize the extraction conditions for the polysaccharides from the roots of Isatis tinctoria L. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis. The 3-D response surface and the contour plots derived from the mathematical models were applied to determine the optimal conditions. The optimal conditions were extraction temperature (X1) 99.5 °C, extraction time (X 2) 3.75 h and ratio of water to raw material (X3) 11.84 (v/w). Under these conditions, the maximal observed value extraction yield of Isatis root polysaccharides (IRPSs) was (11.19 ± 0.04)%, which was agreed with predicted value 11.17%. Pharmacological experiments indicated that IRPS have an appreciable ABTS radical scavenging ability in vitro and could increase IL-4 and IFN-γ mRNA expression in chicken lymphocytes obtaining maximum promoted effects of 70% and 115%, respectively. This study may facilitate a deeper understanding of IRPS to provide theoretical references. © 2011 Elsevier Ltd. All rights reserved.

Zhou H.,Hunan University
2011 International Conference on Multimedia Technology, ICMT 2011 | Year: 2011

Chinese traditional etiquette and custom has remarkable characteristics of intangible culture in the form and the way of inheritance. Based on the concept of intangible culture and characteristics described, the article summarizes the development and current situation of Chinese traditional etiquette and custom that as a part of intangible culture, analyses the aesthetic characteristics and functions of Chinese traditional etiquette and custom, puts forward the aesthetic inheritance of Chinese traditional etiquette and custom in intangible culture perspective: highlighting aesthetic characteristics of traditional etiquette and custom, stimulating aesthetic motivation of traditional etiquette and custom, excavating aesthetic value of traditional etiquette and custom. © 2011 IEEE.

Zeng J.,Hengyang Normal University | Chen K.-Q.,Hunan University
Carbon | Year: 2016

By using nonequilibrium Green's functions in combination with the density functional theory, the spin transport properties of a single-molecule spintronic device are investigated. The computational results show that when the magnetic configuration of the device is set as parallel, the perfect spin-filtering effect can be observed. Especially, this perfect spin-filtering effect is independent of the number of carbon atoms in the carbon chain. However, when the magnetic configuration is set in antiparallel, the spin-filtering effect displays a strong odd-even oscillatory characteristic, namely, the spin-filtering efficiencies of odd-numbered chain systems have a higher values than even-numbered chain systems. Moreover, the magnetoresistance effect can also be observed in this single-molecule spintronic device. In contrast to the odd-even oscillatory characteristic of the spin-filtering effect in the antiparallel magnetic configuration, high magnetoresistance ratios belong to even-numbered chain systems while low magnetoresistance ratios belong to odd-numbered chain systems. The mechanisms are suggested for these interesting phenomena. © 2016 Elsevier Ltd. All rights reserved.

Li Z.Q.,Hunan University
International Journal of Solids and Structures | Year: 2010

Previous experiments have shown that the distinct features of macro-martensitic band nucleation and propagation in micro-tube under tension are in three stages: the initiation and propagation of a single helical band → self-merging → propagation of the cylindrical band. In this paper, the martensitic formation and helical band propagation in the tube at different temperatures are modeled. The free energy function of the tube is formulated by introducing an equivalent method to calculate the stress and strain disturbances in the helical martensitic domain, and the phase transformation criterion is derived based on thermodynamics. The simulations successfully capture the main features of nucleation, pattern evolution and variation of front velocity of the helical martensitic band in the tube. The analytical results and the comparison with experiments are also discussed in this paper. © 2009 Elsevier Ltd. All rights reserved.

Zhang J.,University of Swansea | Fu Y.,Hunan University
Meccanica | Year: 2012

A new beam model is developed for the viscoelastic microbeam based on a modified couple stress model which contains only one material length scale parameter. The governing equations of equilibrium together with initial conditions and boundary conditions are obtained by a combination of the basic equations of modified couple stress theory and Hamilton's principle. This new beam model is then used for an electrically actuated microbeam-based MEMS structure. The dynamic and quasi-static governing equations of an electrically actuated viscoelastic microbeam are firstly given where the axial force created by the midplane stretching effect is also considered. Galerkin method is used to solve above equation and this method is also validated by the finite element method (FEM) when our model is reduced into an elastic case. The numerical results show that the instantaneous pull-in voltage, durable pull-in voltage and pull-in delay time predicted by this newly developed model is larger (longer) than that predicted by the classical beam model. A comparison between the quasi-static model results and the dynamic model results is also given. © 2012 Springer Science+Business Media B.V.

Cheng Y.,Hunan University | Matykina E.,Complutense University of Madrid | Skeldon P.,University of Manchester | Thompson G.,University of Manchester
Electrochimica Acta | Year: 2011

Plasma electrolytic oxidation was undertaken on Zircaloy-4 in alkaline silicate and pyrophosphate electrolytes, with a square waveform AC current regime. The resultant coatings were examined using scanning electron spectroscopy, X-ray diffraction and nanoindentation. The coatings formed in silicate electrolyte comprised mainly a porous inner layer and a more compact outer layer, with characteristic solidification structures being evident following prolonged treatment. The coatings contained monoclinic and tetragonal ZrO2, the latter being mainly present in the outer layer, which was of hardness up to ∼8 GPa. In contrast, extensively cracked coatings resulted from use of pyrophosphate electrolyte; the coating integrity was improved by the addition of silicate to the pyrophosphate electrolyte. The different morphologies of the coatings appeared to be related to the differing nature of the microdischarges and to the incorporation of silicon species that enhanced the formation of t-ZrO2. © 2011 Elsevier Ltd.

Yan Liu X.,Hunan University | Specht E.,iversity Magdeburg
Chemical Engineering Science | Year: 2010

The thermal efficiency of a rotary kiln is predominantly influenced by the amount of lateral mixing of the material bed. In this paper, the fraction of the mixing zone in the material bed is predicted for the rolling motion. For a given material, the fraction is found to depend only on three dimensionless variables-the ratio of the particle diameter to the kiln diameter, the Froude number and the filling degree. Experiments were carried out on a rotating cylinder with beans as testing material. The predicted results are in good agreement with the measurements with a maximal error of 12%. The fraction of the mixing zone is then analyzed for industrial rotary kilns. Its value is found to increase approximately linearly with increasing Froude number and the dynamic angle of repose of the material. For all investigated cases, the fraction of the mixing zone lies in the range of 20-45%. Results of this study can provide orientating values of the mixing zone fraction, which are needed to calculate the thermal efficiency of the rotary kiln. © 2010 Elsevier Ltd. All rights reserved.

Choi K.K.,University of Southern California | Xiao Y.,Hunan University
Journal of Structural Engineering | Year: 2010

This paper describes a numerical program to analyze the behavior of the concrete-filled steel tubular (CFT) stub columns, and predict various modes of lateral interactions between steel tube and filled-in-concrete under axial compression. The behavior of the CFT columns is controlled by both the strength and the confinement effect of steel tube and filled-in-concrete in the columns. Various lateral interactions between steel tube and filled-in-concrete in CFT columns are classified into eight different cases by the contact between steel tube and filled-in concrete at different stress stages. The paper examines the analytical models with various experimental results in literature. The comparisons showed that the numerical program is reasonable to capture mechanical behavior of concrete-filled circular steel tubes. © 2010 ASCE.

Li C.C.,Hunan University | Li C.C.,National University of Singapore | Yin X.M.,National University of Singapore | Li Q.H.,National University of Singapore | Wang T.H.,National University of Singapore
CrystEngComm | Year: 2011

A simple glucose-assisted hydrothermal process has been developed to design complex and functional ZnO/SnO2 nanostructures. In this synthesis, the abundant hydroxyl groups of glucose can ligate with Zn2+ and Sn4+, and induce nucleation. Furthermore, the glucose molecules can form stacking templates to direct the oriented attachment of nanorods and nanoplates due to the π-π electron interactions between glucose ligands. The growth mechanism is studied by changing the synthesis conditions. It is found that the morphologies of ZnO/SnO2 greatly depend on the concentrations of glucose and sodium hydroxide, as well as the molar ratios between Zn2+ and Sn4+. The as-synthesized samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. In particular, gas sensing tests show that these ZnO/SnO2 nanostructures exhibit enhanced sensing properties to ethanol due to the formation of nano-heterojunctions and their unique morphologies. © 2011 The Royal Society of Chemistry.

Zhu Z.-W.,Hunan University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

Numerical simulations for a fixed circular cylinder with diameter of 0.12 m was performed in a two-dimensional (2-D) domain with Reynolds averaged Navier-Stokes (RANS) equations and SST k-w turbulent model. The range of Re number was 1.2×105 to 3.7×105. In order to ensure simulation quality, a suitable computational domain was presented with a gird partition strategy. Based on the obtained time histories of aerodynamic coefficients, mean and root-mean-square values as well as Strouhal (St) numbers, grid and time step independency checks were performed to identify suitable simulation parameters. Then, aerodynamic coefficients and St number of the cylinders at various Re numbers were predicted. After comparing the present results with those of available references, it was shown that 2-D RANS simulations for fixed circular cylinders may not be feasibe to obtain acceptable results.

Wang L.,Hunan University | Wang L.,Key Laboratory of Building Safety and Energy Efficiency | Rega G.,University of Rome La Sapienza
International Journal of Solids and Structures | Year: 2010

In this study, the 3D nonlinear equations of motion of the suspended cable with moving mass are obtained via the Hamilton principle, and its transient linear planar dynamics is investigated. Considering the quasi-static assumption, the condensed planar model accounting for the effect of the moving mass is derived, and it is then discretized by choosing the static deflection and sine series as shape functions. It is shown that this expansion shows good convergence features. The Newmark method is used to investigate the transient response. The effects of the inertia force, mass, sag and velocity of the moving mass on the transient dynamics of the suspended cable are systematically investigated. Finally, the horizontal tension of the suspended cable and the case of sequentially moving masses are examined. © 2010 Elsevier Ltd. All rights reserved.

Sinha C.,Hunan University | Sinha C.,Lund University | Gardenfors P.,Lund University
Annals of the New York Academy of Sciences | Year: 2014

We propose an event-based account of the cognitive and linguistic representation of time and temporal relations. Human beings differ from nonhuman animals in entertaining and communicating elaborate detached (as opposed to cued) event representations and temporal relational schemas. We distinguish deictically based (D-time) from sequentially based (S-time) representations, identifying these with the philosophical categories of A-series and B-series time. On the basis of cross-linguistic data, we claim that all cultures employ both D-time and S-time representations. We outline a cognitive model of event structure, emphasizing that this does not entail an explicit, separate representation of a time dimension. We propose that the notion of an event-independent, metric "time as such" is not universal, but a cultural and historical construction based on cognitive technologies for measuring time intervals. We critically examine claims that time is universally conceptualized in terms of spatial metaphors, and hypothesize that systematic space-time metaphor is only found in languages and cultures that have constructed the notion of time as a separate dimension. We emphasize the importance of distinguishing what is universal from what is variable in cultural and linguistic representations of time, and speculate on the general implications of an event-based understanding of time. © 2014 New York Academy of Sciences.

Recipiency is an indispensable element in any talk-in-interaction. This paper focuses on Mandarin task-oriented interaction on a moment-by-moment basis in order to study this phenomenon of recipiency in more detail. The aim is to describe the interrelationships between the orientation towards recipiency that participants display and their spontaneous choices of reactive tokens. This paper uses a conversation analytic perspective to show that reactive tokens are systematically employed as a negotiating resource to manifest different levels of recipiency. Moreover, these levels of recipiency can be represented as a cline: silent. →. passive. →. neutral. →. active. →. affiliative. This model suggests that recipients employ reactive tokens as a negotiating resource to collaboratively achieve, in the emerging interaction, either disengagement or involvement on this continuum of displayed recipiency. Recipients negotiate their rights to shape and reshape the trajectory of the ongoing interaction by privileging different reactive tokens. The model of recipiency suggests that the most proficient listenership is the one that exhibits knowledge of how to react by choosing the best reactive token on the basis of the varying and ongoing interactive circumstances. © 2014 Elsevier B.V.

Hu A.,Hunan University | Cao G.,Guangdong Pharmaceutical University
Tetrahedron Asymmetry | Year: 2011

The hydrobromide and nitrate of 4-(tert-butyl)-5-(4-chlorobenzyl)thiazol-2- amine have been synthesized, and their chiral symmetry breaking in the solid-state has been investigated. It is shown that each molecule is connected by continuous N-H⋯Br/N-H⋯O hydrogen bonds to afford left- or right-handed helical assemblies in the crystal packing. Mirror-image CD spectra were obtained for the right- and left-handed helical-type chiral crystals. © 2011 Elsevier Inc. All rights reserved.

On the basis of copper-enhanced gold nanoparticle tags as an amplification approach, we introduced, in this paper, magnetic nanoparticles for further improving performance of electrochemical immunoassay by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. Due to the use of antibody-immobilized magnetic nanoparticles, the immunoreaction between antibody and antigen takes place in a homogeneous bulk solution phase. Compared with traditional solid interface reaction, the proposed strategy can provide some advantages such as easy of separation, shorter analytical time, wider linear range, and lower detection limit. It was also successfully applied to HBsAg determination in a linear range of 0.1-1500ngmL -1 with a detection limit of 87pgmL -1. The proposed analytical strategy holds good selectivity, sensitivity and repeatability and also great promise for the extended application in the fields of clinical diagnosis, bio-affinity assay and environmental monitoring. © 2010 Elsevier B.V.

Zhu Z.-W.,Hunan University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2015

In order to investigate the feasibility of two-dimensional (2D) RANS model on prediction of vortex shedding characteristics of bridge flat box girders, the CFD simulations were performed to represent the flow field around the stiffening girder of the Great Belt East Bridge main crossing, based on 2D RANS model combined with SST k-ω turbulent model at Re=1.06×105. The flow results, including mean and fluctuating aerodynamic coefficients, as well as vortex-shedding Strouhal number were presented under different time step sizes and grid arrangements. The research highlighted the quality insurance on time step size and grid resolution when performing CFD simulation. The results show that referring to the computed vortex-shedding period of T, 2D RANS model can present an approximate estimation of mean aerodynamic coefficients on large time step size, but can not estimate a stable vortex-shedding Sr number until the time step size is smaller than T/260. Also 2D RANS model can present a good approximate estimation of mean aerodynamic coefficients, but the predicted vortex shedding Sr number is quite different from the results from wind tunnel tests. ©, 2015, Xi'an Highway University. All right reserved.

Fang Q.H.,University of New South Wales | Fang Q.H.,Hunan University | Zhang L.C.,University of New South Wales
Acta Materialia | Year: 2013

This paper establishes an analytical model to predict the normal threshold load that causes the emission of partial dislocations in silicon during nanoscratching. In the modeling, the deformation mechanisms and the sequence of microstructural changes already explored by experiment and molecular dynamics will be exactly followed; that is, with increasing the normal load of nanoscratching, phase transformation first takes place, followed by partial dislocation emission from the interface between the phase transformed zone and the original crystalline silicon when the scratching load reaches its threshold. The model postulates that the emission process represents the generation of a dipole of Shockley partial dislocations. One partial dislocation of the dipole, located at the interface, is considered immobile, while the other partial dislocation moves into the bulk of the crystalline silicon. The mobile partial dislocation slips along a crystallographic plane, and a stacking fault is formed in its wake. Based on the above, the threshold normal scratching load for the emission of a partial dislocation is determined by means of the energy criterion. The influence of the indenter geometry and the location of dislocation nucleation on the threshold normal scratching load is then investigated. Compared with the deformation of silicon under nanoindentation, the present study concludes that the threshold load under scratching is always smaller, and that a sharp indenter leads to a relatively smaller threshold load. The model prediction is well verified by scratching experiments. Copyright © 2013 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.

Zeng F.,Hunan University | Li C.,Michigan Technological University | Tian Z.,Michigan Technological University
IEEE Journal on Selected Topics in Signal Processing | Year: 2011

In wideband cognitive radio (CR) networks, spectrum sensing is an essential task for enabling dynamic spectrum sharing, but entails several major technical challenges: very high sampling rates required for wideband processing, limited power and computing resources per CR, frequency-selective wireless fading, and interference due to signal leakage from other coexisting CRs. In this paper, a cooperative approach to wideband spectrum sensing is developed to overcome these challenges. To effectively reduce the data acquisition costs, a compressive sampling mechanism is utilized which exploits the signal sparsity induced by network spectrum under-utilization. To collect spatial diversity against wireless fading, multiple CRs collaborate during the sensing task by enforcing consensus among local spectral estimates; accordingly, a decentralized consensus optimization algorithm is derived to attain high sensing performance at a reasonable computational cost and power overhead. To identify spurious spectral estimates due to interfering CRs, the orthogonality between the spectrum of primary users and that of CRs is imposed as constraints for consensus optimization during distributed collaborative sensing. These decentralized techniques are developed for both cases of with and without channel knowledge. Simulations testify the effectiveness of the proposed cooperative sensing approach in multi-hop CR networks. © 2011 IEEE.

Provis J.L.,University of Sheffield | Palomo A.,CSIC - Eduardo Torroja Institute for Construction Science | Shi C.,Hunan University
Cement and Concrete Research | Year: 2015

Alkali activation is a highly active and rapidly developing field of activity in the global research and development community. Commercial-scale deployment of alkali-activated cements and concretes is now proceeding rapidly in multiple nations. This paper reviews the key developments in alkali-activated materials since 2011, with a particular focus on advances in characterisation techniques and structural understanding, binder precursors and activation approaches, durability testing and design, processing, and sustainability. The scientific and engineering developments described in this paper have underpinned the on-going scale-up activities. We also identify important needs for future research and development to support the optimal and appropriate utilisation of alkali activated materials as a component of a sustainable future construction materials industry. © 2015 Elsevier B.V. All rights reserved.

Tram K.,McMaster University | Kanda P.,McMaster University | Salena B.J.,McMaster University | Huan S.,Hunan University | Li Y.,McMaster University
Angewandte Chemie - International Edition | Year: 2014

Microbial pathogens pose serious threats to public health and safety, and results in millions of illnesses and deaths as well as huge economic losses annually. Laborious and expensive pathogen tests often represent a significant hindrance to implementing effective front-line preventative care, particularly in resource-limited regions. Thus, there is a significant need to develop low-cost and easy-to-use methods for pathogen detection. Herein, we present a simple and inexpensive litmus test for bacterial detection. The method takes advantage of a bacteria-specific RNA-cleaving DNAzyme probe as the molecular recognition element and the ability of urease to hydrolyze urea and elevate the pH value of the test solution. By coupling urease to the DNAzyme on magnetic beads, the detection of bacteria is translated into a pH increase, which can be readily detected using a litmus dye or pH paper. The simplicity, low cost, and broad adaptability make this litmus test attractive for field applications, particularly in the developing world. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yang H.,Hunan University | Prudencio E.E.,University of Texas at Austin | Cai X.-C.,University of Colorado at Boulder
International Journal for Numerical Methods in Engineering | Year: 2012

We develop a parallel fully implicit domain decomposition algorithm for solving optimization problems constrained by time-dependent nonlinear partial differential equations. In particular, we study the boundary control of unsteady incompressible Navier-Stokes equations. After an implicit discretization in time, a fully coupled sparse nonlinear optimization problem needs to be solved at each time step. The class of full space Lagrange-Newton-Krylov-Schwarz algorithms is used to solve the sequence of optimization problems. Among optimization algorithms, the fully implicit full space approach is considered to be the easiest to formulate and the hardest to solve. We show that Lagrange-Newton-Krylov-Schwarz, with a one-level restricted additive Schwarz preconditioner, is an efficient class of methods for solving these hard problems. To demonstrate the scalability and robustness of the algorithm, we consider several problems with a wide range of Reynolds numbers and time step sizes, and we present numerical results for large-scale calculations involving several million unknowns obtained on machines with more than 1000 processors. © 2012 John Wiley & Sons, Ltd.

Zhou Q.,Hunan University | Zeng D.,Central South University | Voigt W.,TU Bergakademie Freiberg
Fluid Phase Equilibria | Year: 2012

A reaction model was developed to describe the thermodynamic properties of aqueous electrolyte solutions. In the model various types of association (ion-solvent, ion-ion) are incorporated using as much as possible structure information. In the framework of the model, an electrolyte aqueous solution is treated as a mixture of charged or neutral associated species consisting of cations, anions and the solvent water, among the species the short range interactions are assumed to be equal. The abundance of each species is determined by its specific Gibbs energy of formation related to the assumed master species. The total Gibbs energy of mixing consists of a long range electrostatic term and short range interaction terms, the latter are sum of Gibbs energy of all species. Based on the total Gibbs energy of mixing, activity expressions for each species were derived. The Gibbs energy of formation of each associated species is correlated by its stepwise formation Gibbs energies, thus reducing the number of necessary adjustable parameters. At the example systems CuCl 2-MCln-H 2O (M=Li, Ca, Mg) model parameters were determined by fitting experimental data of water activities and solubilities on the basis of ion associates in agreement with available structure information. Component activities, solubility isotherms and species abundances were calculated and compared with experimental results. This facilitates an understanding of structure-property relationships in the titled systems. © 2012 Elsevier B.V.

Oil flooded compression with regenerator (OFCR) is one of the possible technologies to improve the performance of air conditioner. The addition of OFCR system to basic vapor compression system adds several components: oil separator, oil cooler and regenerator. These components can lead to a significant increase in performance. In this study, parametric studies of these components performance have been carried out under various operating conditions. Compared with basic vapor compression system, COP of OFCR system with 100% effective regenerator is improved by 0.7-11.8% while COP of OFCR system without regenerator is reduced by 0.6-1.8%. When oil temperature exiting the oil cooler reaches 40 °C and 50 °C, the performance of OFCR system is worse than that of basic system at evaporation temperature Te = 15 °C and Te ≥ 5 °C respectively. COP and cooling capacity of OFCR with solubility are decreased by 6.9% and 14.3% respectively at Te = 5 °C and 0.4 oil mass fraction. A modification of OFCR system is suggested for reducing the negative effects of solubility. The results of COP and cooling capacity show that the modified OFCR system has a 3-4% performance improvement. Comprehensive effects of regenerator efficiency, oil temperature and solubility are also studied. Taking the solubility into account, the effects of regenerator efficiency and oil temperature are slightly different from that without solubility. © 2015 Elsevier Ltd. All rights reserved.

Liu Q.H.,Hunan University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

Developing the analysis of the distribution of the so-called posmom xp to some molecular rotational states for diatomic molecules and spherical cage molecules, we obtain posmometry (introduced recently by Bernard and Gill, 2010 [5]) of the spherical harmonics and demonstrate that it is similar to the momentum distributions of the stationary states for a one-dimensional simple harmonic oscillator. The results are not only potentially experimentally testable but also reflect a fact that the embedding of the two-dimensional spherical surface S2 in three-dimensional flat space R3 is physically self-consistent and appealing. © 2014 Elsevier B.V.

Zhang L.,Central South University of forestry and Technology | Zhang L.,Hunan University | Wang R.,Central South University of forestry and Technology
International Journal of Advanced Manufacturing Technology | Year: 2013

Low-pressure die-cast (LPDC) is widely used in manufacturing thin-walled aluminum alloy products. Since the quality of LPDC parts are mostly influenced by process conditions, how to determine the optimum process conditions becomes the key to improve the part quality. In this paper, a combining artificial neural network and genetic algorithm (ANN/GA) method is proposed to optimize the LPDC process. In this method, considering the more complicated preparation process of thin-walled casting, an ANN model combining learning vector quantization and back-propagation (BP) algorithm is proposed to map the complex relationship between process conditions and quality indexes of LPDC. Meanwhile, the orthogonal array design and numerical simulation is applied to obtain the training samples instead of carrying out a real experiment for the sake of cost saving. The genetic algorithm is employed to optimize the process parameters with the fitness function based on the trained ANN model. Then, by applying the optimized parameters, a thin-walled component of 300 mm in length, 100 mm in width, and 1.5 mm in thickness is successfully prepared. The results indicate that the proposed intelligent system is an effective tool for the process optimization of LPDC. © 2012 Springer-Verlag London Limited.

Zhu Z.-W.,Hunan University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2014

In order to investigate the frequency-domain characteristics and spatial coherence of fluctuating pressure on box girder surface, large eddy simulation (LES) was employed to simulate the flow field at zero angle of attack with Re of 1.27×105. The fluctuating pressure distribution and their statistical characteristics were obtained. Spatial coherence analysis and frequency-domain analysis of fluctuating pressure time history were carried out to investigate the flow mechanism. The results show that the primary shedding vortex in the wake dominates the fluctuating pressure field, and vortex shedding indicates a band width distribution in frequency-domain due to not simultaneous shedding in span-wise direction. The pressure records on girder lower surface are highly correlated in-phase, while the pressures on upper surface is significantly interfered by the reattachment flow, resulting in a 180 degree phase shift between pressures on the leading and trailing air fairing. Consequently, the fluctuating pressure on the upper surface of the leading air fairing is completely in antiphase with that of the trailing air fairing, and the correlation of fluctuating pressure at large area behind the average flow reattachment zone is significantly decreased with random phase.

Long Y.,Hunan University | Yue X.,Guilin University of Technology
Advances in Information Sciences and Service Sciences | Year: 2012

Based on the data of input-output table 2007 in China, the paper selected 10 departments including paper and paper products industry, printing and reproduction of record media industry, cultural goods manufacturing, toys sports manufacturing industry, household audio-visual equipment manufacturing industry, culture and office machinery manufacturing industry, arts and crafts manufacturing, tourism arts and culture radio film and television industry, the entertainment industry as the cultural industry, and constructed a 52×52sectors input-output table, to analysis the direct consumption coefficient of cultural industry and response coefficient and the influence coefficient in China, and to reveal the association between the cultural industry and the second industry and the tertiary industry, and illustrated that the cultural industry plays an important role in promoting the national economy. The analysis on the above 10 departments illustrated the input-output relationship between various departments of cultural industry, and as well as what the position and role of various departments of cultural industry plays in the process of realization of the cultural industry cluster, and pointed out the industrial sectors during the development of cultural industry gathering and the industrial sectors which needs more effective guidance.

Wu G.,National Science Foundation | Zhang Y.-J.,Hunan University
Energy Policy | Year: 2014

Whether China's crude oil imports are the culprit of oil price volatility these years has not been quantitatively confirmed. Therefore, this paper empirically investigates the role of China's crude oil net imports in Brent price changes from October 2005 to November 2013 based on an econometric analysis. The results indicate that, during the sample period, China's crude oil imports do not significantly affect Brent price changes, no matter in the long run or short run. Therefore, the blame for China's crude oil imports to cause the dramatic fluctuations of international oil price has no solid evidence. Also, there exists significant uni-directional causality running from the Brent price to China's crude oil imports at the 5% level. Besides, the response of the Brent price to China's crude oil imports is found positive but slight, and the Brent price responds more significantly to US dollar exchange rate and OECD commercial inventory than to China's crude oil imports in the short run. Finally, the contribution of China's crude oil imports to Brent price movement is about 10%, which is less than that of US dollar exchange rate but larger than that of Indian crude oil imports or OECD commercial inventory. © 2014 Elsevier Ltd.

Wang C.,Nanjing Southeast University | Zhong Z.,Nanjing Southeast University | E J.,Hunan University
Powder Technology | Year: 2012

Recurrence plot and recurrence quantification analysis was applied into the analysis of the pressure fluctuation signals in spouted bed, and some parameters including recurrence rate, determinism, laminarity, averaged diagonal line length, trapping time and entropy were extracted from recurrence plots. Based on these characteristic parameters, least square support vector machine was applied to recognize the flow regimes, and parameters in least square support vector machine were optimized by adaptive genetic optimization algorithm. The recognition accuracies of packed bed, stable spouting, bubbly fluidized bed and slugging bed could reach 85%, 85%, 80% and 90% respectively. © 2011 Elsevier B.V.

Zhou Y.,Japan National Institute of Advanced Industrial Science and Technology | Yin S.,Hunan University | Gao Y.,Xiamen University | Zhao Y.,Xiamen University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2010

(Chemical Equation Presented) Different copper complexes selectively catalyze the aerobic oxidative coupling of H-phosphonates to afford either hypophosphates and pyrophosphates in high yields with high selectivity (see scheme; tmeda = N, N, N', N'-tetramethylethylenediamine). © 2010 Wiley-VCH Verlag GmbH &. Co. KGaA, Weinheim.

Jiang J.,Ningbo Institute of Materials Technology and Engineering | Jiang J.,Hunan University | Sun J.,Ningbo Institute of Materials Technology and Engineering | Dou W.,Ningbo Institute of Materials Technology and Engineering | Wan Q.,Ningbo Institute of Materials Technology and Engineering
IEEE Electron Device Letters | Year: 2012

Junctionless flexible oxide-based electric-double-layer thin-film transistors (TFTs) are fabricated on paper substrates at room temperature. Channel and source/drain electrodes are realized by an indium-tin-oxide (ITO) film without any source/drain junction. Effective field-effect modulation of drain current can be obtained when the thickness of the top ITO film is decreased to 20 nm. These junctionless paper TFTs show a good device performance with a small subthreshold swing of 0.21 V/dec and a large on/off ratio of 2 × 10 6. Such junctionless paper TFTs can provide a new opportunity for flexible paper electronics and low-cost portable-sensor applications. © 2011 IEEE.

Yuan L.,Hunan University | Zuo Q.-P.,First Hospital of Changsha
Chemistry - An Asian Journal | Year: 2014

Hydrogen sulfide (H2S) is connected with various physiological and pathological functions. However, understanding the important functions of H2S remains challenging, in part because of the lack of tools for detecting endogenous H2S. Herein, compounds Ratio-H2S 1/2 are the first FRET-based mitochondrial-targetable dual-excitation ratiometric fluorescent probes for H2S on the basis of H2S-promoted thiolysis of dinitrophenyl ether. With the enhancement of H2S concentration, the excitation peak at λ≈402 nm of the phenolate form of the hydroxycoumarin unit drastically increases, whereas the excitation band centered at λ≈570 nm from rhodamine stays constant and can serve as a reference signal. Thus, the ratios of fluorescence intensities at λ=402 and 570 nm (I402/I570) exhibit a drastic change from 0.048 in the absence of H2S to 0.36 in the presence of 180 μM H 2S; this is a 7.5-fold variation in the excitation ratios. The favorable properties of the probe include the donor and acceptor excitation bands, which exhibit large excitation separations (up to 168 nm separation) and comparable excitation intensities, high sensitivity and selectivity, and function well at physiological pH. In addition, it is demonstrated that the probe can localize in the mitochondria and determine H2S in living cells. It is expected that this strategy will lead to the development of a wide range of mitochondria-targetable dual-excitation ratiometric probes for other analytes with outstanding spectral features, including large separations between the excitation wavelengths and comparable excitation intensities. Don't panic - FRET! The first Förster resonance energy transfer (FRET)-based dual-excitation ratiometric fluorescent probe for monitoring H2S in mitochondrial of living cells is described (see picture). Favorable properties of the probe include large separations of the donor and acceptor excitation bands, comparable excitation intensities, high sensitivity and selectivity, and good function at physiological pH. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu M.R.,Hunan University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2012

To compare the difference in the efficacy on osteoarthritis of the knee between the ultrastructural acupotomy therapy at the counter-Ashi points and the conventional acupuncture-moxibustion therapy. Sixty cases were randomly devided into an ultrastructural acupotomy therapy group (group A) and a conventional acupuncture-moxibustion group (group B), 30 cases in each one. In the group A, the ultrastructural acupotomy therapy was applied to the counter-Ashi points in which pain was alleviated or disappeared on pressure. The treatment was given once a week, lasting for 1 month. In the group B, the acupuncture-moxibustion therapy was applied to Dubi (ST 35), Neixiyan (EX-LE 4), Zusanli (ST 36), Yanglingquan (GB 34), etc. The treatment was given once daily, lasting for 1 month. Before and after treatment, the Visual Analogue Scale (VAS), Lysholm knee joint scale and the affected knee joint flexion angle were observed in the two groups. The clinical efficacy was compared between the two groups. After treatment, the scores of VAS, Lysholm knee joint scale and the affected knee joint flexion angle were improved obviously as compared with those before treatment in either group (P < 0.01, P < 0.05). The results of them in the group A were superior apparently to those in the group B (all P < 0.05). The total effective rate in the group A was superior to that in the group B [80.0% (24/30) vs 60.0% (18/30), P < 0.05]. The ultrastructural acupotomy therapy at the counter-Ashi points achieves the superior clinical efficacy on osteoarthritis of the knee as compared with the conventional acupuncture therapy. It relieves pain and improves the motion range of knee joint effectively. It is simple in operation and less in treatment frequency.

Liu Q.H.,Hunan University | Xiao S.F.,Zhanjiang Normal University
International Journal of Geometric Methods in Modern Physics | Year: 2015

With acceptance of the Dirac's observation that the canonical quantization entails using Cartesian coordinates, we examine the operator erPr rather than Pr itself and demonstrate that there is a decomposition of erPr into a difference of two self-adjoint but noncommutative operators, in which one is the total momentum and another is the transverse one. This study renders the operator Pr indirectly measurable and physically meaningful, offering an explanation of why the mean value of Pr over a quantum mechanical state makes sense and supporting Dirac's claim that Pr "is real and is the true momentum conjugate to r". © 2015 World Scientific Publishing Company.

Zhou W.,Harbin Institute of Technology | Li H.,Harbin Institute of Technology | Yuan F.-G.,North Carolina State University | Yuan F.-G.,Hunan University
Ultrasonics | Year: 2015

A new piezoelectric wafer made from a PMN-PT single crystal with dominant piezoelectric coefficient d36 is proposed to generate and detect guided waves on isotropic plates. The in-plane shear coupled with electric field arising from the piezoelectric coefficient is not usually present for conventional piezoelectric wafers, such as lead zirconate titanate (PZT). The direct piezoelectric effect of coefficient d36 indicates that under external in-plane shear stress the charge is induced on a face perpendicular to the poled z-direction. On thin plates, this type of piezoelectric wafer will generate shear horizontal (SH) waves in two orthogonal wave propagation directions as well as two Lamb wave modes in other wave propagation directions. Finite element analyses are employed to explore the wave disturbance in terms of time-varying displacements excited by the d36 wafer in different directions of wave propagation to understand all the guided wave modes accurately. Experiments are conducted to examine the voltage responses received by this type of wafer, and also investigate results of tuning frequency and effects of d31 piezoelectric coefficient, which is intentionally ignored in the finite element analysis. All results demonstrate the main features and utility of proposed d36 piezoelectric wafer for guided wave generation and detection in structural health monitoring. © 2014 Elsevier B.V. All rights reserved.

Guan X.,Tongji University | Sun Y.,Tongji University | Qin H.,Tongji University | Li J.,Tongji University | And 3 more authors.
Water Research | Year: 2015

Over the past 20 years, zero-valent iron (ZVI) has been extensively applied for the remediation/treatment of groundwater and wastewater contaminated with various organic and inorganic pollutants. Based on the intrinsic properties of ZVI and the reactions that occur in the process of contaminants sequestration by ZVI, this review summarizes the limitations of ZVI technology and the countermeasures developed in the past two decades (1994-2014). The major limitations of ZVI include low reactivity due to its intrinsic passive layer, narrow working pH, reactivity loss with time due to the precipitation of metal hydroxides and metal carbonates, low selectivity for the target contaminant especially under oxic conditions, limited efficacy for treatment of some refractory contaminants and passivity of ZVI arising from certain contaminants. The countermeasures can be divided into seven categories: pretreatment of pristine ZVI to remove passive layer, fabrication of nano-sized ZVI to increase the surface area, synthesis of ZVI-based bimetals taking advantage of the catalytic ability of the noble metal, employing physical methods to enhance the performance of ZVI, coupling ZVI with other adsorptive materials and chemically enhanced ZVI technology, as well as methods to recover the reactivity of aged ZVI. The key to improving the rate of contaminants removal by ZVI and broadening the applicable pH range is to enhance ZVI corrosion and to enhance the mass transfer of the reactants including oxygen and H+ to the ZVI surface. The characteristics of the ideal technology are proposed and the future research needs for ZVI technology are suggested accordingly. © 2015 Elsevier Ltd.

Lin S.P.,Sun Yat Sen University | Zheng Y.,Sun Yat Sen University | Cai M.Q.,Hunan University | Wang B.,Sun Yat Sen University
Applied Physics Letters | Year: 2010

A phenomenological thermodynamic model of ferroelectric nanowires is developed to investigate the size-temperature phase diagrams. Considering existence of the surface tension, size, and external applied stress effects, the approximated expressions of the transition temperatures at which the paraelectric phase loses its stability with respect to the appearance of the spontaneous polarization are derived. At the same time, the size-temperature phase diagrams as functions of the ferroelectric nanowire radius are obtained, and also show its external mechanical stress controllability. © 2010 American Institute of Physics.

Zou J.Y.,Hunan University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2012

To analyze the chemical constituents of volatile oil from the rhizomes and leaves of Pileostegia viburnoides var. glabrescens by GC-MS. The volatile oil was extracted from the rhizomes and leaves of Pileostegia viburnoides var. glabrescens by steam distillation. The constituents of volatile oil were identified by GC-MS technology. 37 compounds were identified from the oil of rhizomes. 36 compounds were identified from the oil of leaves. The rhizomes and leaves volatile oil had 18 compounds in common. This study is the first one to report the volatile components of Pileostegia viburnoides var. glabrescens. It can provide a scientific basis for rational use of the rhizomes and leaves of Pileostegia viburnoides var. glabrescens.

Shi C.,Hunan University | Jimenez A.F.,CSIC - Eduardo Torroja Institute for Construction Science | Palomo A.,CSIC - Eduardo Torroja Institute for Construction Science
Cement and Concrete Research | Year: 2011

Preparation of this article entailed authors analyzing the contents of quite a number of papers, although the main objective was never to review the state of the art of new cements. Rather authors intend to discuss why they believe alkaline activated cement can be positioned at the epicentre of a new and necessary transition from today's Portland cement to the new cements of the future. A brief history of alkaline cements serves as an introduction to the technology itself. The interest roused around calcium sulfoaluminate-based cements is also reviewed, albeit summarily. The greater part of the article focuses, however, on alkaline cements which are classified into five categories. The fundamental chemical and structural characteristics of aluminosilicate- based alkaline cements are also described, and the key advances made in the understanding of synthetic gels are discussed. The paper ultimately finds hybrid cements to be technologically viable materials for contemporary construction. © 2011 Elsevier Ltd. All rights reserved.

Liu D.,Xian Jiaotong - Liverpool University | Lee M.-C.,Chinese University of Hong Kong | Pun C.-M.,University of Macau | Liu H.,Hunan University
IEEE Transactions on Vehicular Technology | Year: 2013

One major concern of existing wireless localization systems is the identification of nonline-of-sight (NLOS) signal propagation, since NLOS can be considered the dominant source of localization error. Present identification methods usually assume that NLOS could make it not possible to perform localization in a consistent manner. However, the validity of the foregoing assumption has not been properly investigated. This paper presents a theoretical analysis of mobile user localization involving one or more NLOS beacons and shows the given assumption as being invalid when the estimated user location is outside the convex hull of the beacons used in the localization. It also proposes an efficient algorithm for checking whether the estimated location of a mobile user is inside the convex-hull region in both 2-D and 3-D space. Extensive localization experiments on different wireless networks demonstrate that using current NLOS identification methods and classical localization algorithms could yield localization results with grossly underestimated errors. © 2012 IEEE.

Hu H.,Nanyang Technological University | Duan H.,Institute of Materials Research and Engineering of Singapore | Duan H.,Hunan University | Yang J.K.W.,Institute of Materials Research and Engineering of Singapore | Shen Z.X.,Nanyang Technological University
ACS Nano | Year: 2012

In this work, we performed a systematic study on the photoluminescence and scattering spectra of individual gold nanostructures that were lithographically defined. We identify the role of plasmons in photoluminescence as modulating the energy transfer between excited electrons and emitted photons. By comparing photoluminescence spectra with scattering spectra, we observed that the photoluminescence of individual gold nanostructures showed the same dependencies on shape, size, and plasmon coupling as the particle plasmon resonances. Our results provide conclusive evidence that the photoluminescence in gold nanostructures indeed occurs via radiative damping of plasmon resonances driven by excited electrons in the metal itself. Moreover, we provide new insight on the underlying mechanism based on our analysis of a reproducible blue shift of the photoluminescence peak (relative to the scattering peak) and observation of an incomplete depolarization of the photoluminescence. © 2012 American Chemical Society.

A probability density evolution method (PDEM) based methodology is proposed for the investigation of stochastic dynamic stability control of structures, where the fractional order state feedback control is specifically considered. This study is established based on the probability dissipated system, where the probability density evolution equation for probability dissipated system provides the quantitative basis, say the probability of stability. In such methodology, a newly developed criterion is incorporated to identify the controlled structure is dynamically stable or not. Numerical examples are carried out for the purpose of illustration. The results reveal that the stability-related performance can be significantly improved with application of fractional-type viscoelastic dampers to the structure, which is originally prone to dynamic instability under dynamic excitations. © 2015 Elsevier Ltd. All rights reserved.

Wang H.,Nanjing University of Technology | Zhou G.,Nanjing University of Technology | Gai H.,Hunan University | Chen X.,Nanjing University of Technology
Chemical Communications | Year: 2012

A fluorescent probe based on fluorescein displays excellent selectivity and sensitivity for cysteine and its application for bio-imaging is described. © 2012 The Royal Society of Chemistry.

Zheng G.-H.,Hunan University
Inverse Problems in Science and Engineering | Year: 2015

In this paper, a concentration identification problem of the time fractional inhomogeneous diffusion equation (TFIDE) is investigated. The TFIDE is obtained from the classical diffusion equation by replacing the first-order time derivative by the Caputo fractional derivative of order (Formula presented.) (Formula presented.). Our purpose is to recover the solute concentration from source measurement and boundary data. We show that this problem is severely ill-posed and further apply a convolution-type regularization method to solve it. Convergence estimates are given under a priori bound assumptions for the exact solution. Finally, we provide two numerical examples to confirm our theoretical analysis and show that the corresponding numerical method works effectively. © 2014 Taylor & Francis.

Su R.,Hunan University
Advance Journal of Food Science and Technology | Year: 2015

Supply chain integration can promote the development of local economy effectively, especially the development of agricultural supply chain. In this study, we test the long-term relationship between supply chain and local economy by using time series model. According to the VAR model, it can be seen that the agriculture supply chain promotes food processing industry growth. LnASC at lag 1 period increased one percentage can drive LnFPI growth by 1.28%, LnASC at lag 2 period increased one percentage can drive LnFPI growth by 0.22%, so the effect of agriculture supply chain on food processing industry is obvious. Therefore, agriculture supply chain and food processing industry have direct mutual promotion effect. The development of agricultural supply chain has a significant role in promoting the local economy and promoting employment. © 2015 Maxwell Scientific Publication Corp.

Yin K.,University of South China | Liao D.,Hunan University | Tang C.-K.,University of South China
Molecular Medicine | Year: 2010

Atherosclerosis is characterized by a chronic inflammatory condition that involves numerous cellular and molecular inflammatory components. A wide array of inflammatory mediators, such as cytokines and proteins produced by macrophages and other cells, play a critical role in the development and progression of the disease. ATP-binding membrane cassette transporter A1 (ABCA1) is crucial for cellular cholesterol efflux and reverse cholesterol transport (RCT) and is also identified as an important target in antiatherosclerosis treatment. Evidence from several recent studies indicates that inflammation, along with other atherogenic- related mediators, plays distinct regulating roles in ABCA1 expression. Proatherogenic cytokines such as interferon (IFN)-γ and interleukin (IL)-1β have been shown to inhibit the expression of ABCA1, while antiatherogenic cytokines, including IL-10 and transforming growth factor (TGF)-β1, have been shown to promote the expression of ABCA1. Moreover, some cytokines such as tumor necrosis factor (TNF)-α seem to regulate ABCA1 expression in species-specific and dose-dependent manners. Inflammatory proteins such as C-reactive protein (CRP) and cyclooxygenase (COX)-2 are likely to inhibit ABCA1 expression during inflammation, and inflammation induced by lipopolysaccharide (LPS) was also found to block the expression of ABCA1. Interestingly, recent experiments revealed ABCA1 can function as an antiinflammatory receptor to suppress the expression of inflammatory factors, suggesting that ABCA1 may be the molecular basis for the interaction between inflammation and RCT. This review aims to summarize recent findings on the role of inflammatory cytokines, inflammatory proteins, inflammatory lipids, and the endotoxin-mediated inflammatory process in expression of ABCA1. Also covered is the current understanding of the function of ABCA1 in modulating the immune response and inflammation through its direct and indirect antiinflammatory mechanisms including lipid transport, high-density lipoprotein (HDL) formation and apoptosis. © 2010 The Feinstein Institute for Medical Research.

Wang Q.-Y.,Hunan University | Kang Y.-J.,Jiangnan University
Nanoscale Research Letters | Year: 2016

In this study, we have developed an efficient method based on single-stranded DNA (ssDNA) aptamers along with silica fluorescence nanoparticles for bacteria Salmonella typhimurium detection. Carboxyl-modified Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (RuBPY)-doped silica nanoparticles (COOH-FSiNPs) were prepared using reverse microemulsion method, and the streptavidin was conjugated to the surface of the prepared COOH-FSiNPs. The bacteria S. typhimurium was incubated with a specific ssDNA biotin-labeled aptamer, and then the aptamer-bacteria conjugates were treated with the synthetic streptavidin-conjugated silica fluorescence nanoprobes (SA-FSiNPs). The results under fluorescence microscopy show that SA-FSiNPs can be applied effectively for the labeling of bacteria S. typhimurium with great photostable property. To further verify the specificity of SA-FSiNPs out of multiple bacterial conditions, variant concentrations of bacteria mixtures composed of bacteria S. typhimurium, Escherichia coli, and Bacillus subtilis were treated with SA-FSiNPs. In addition, the feasibility of SA-FSiNPs for bacteria S. typhimurium detection in chicken samples was assessed. All the results display that the established aptamer-based nanoprobes exhibit the superiority for bacteria S. typhimurium detection, which is referentially significant for wider application prospects in pathogen detection. © 2016, Wang and Kang.

Liu M.,Hunan University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2011

To observe the effects of moxibustion on contents of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) expression in the gastric mucosa tissue in rats with gastric mucosal lesion. Thirty-six SD rats were randomly and equally divided into control, model and moxibustion groups. Gastric mucosal lesion model was duplicated by restraint and cool water immersion stress. Pre-moxibustion was applied to "Zusanli" (ST 36) and "Zhongwan" (CV 12), "Pishu" (BL 20) and "Weishu" (BL 21) alternately, once everyday for 8 days before modeling. The contents of EGF and TGF-alpha in gastric mucosa were detected by enzyme-linked immunosorbent assay (ELISA) and the expression of EGFR determined by immunohistochemistry. Compared with the control group, only TGF-alpha content in the gastric mucosa in the model group was increased significantly (P < 0.05). Compared with the model group, the EGF and TGF-alpha contents and EGFR immunoactivity in the gastric mucosa were increased significantly in the moxibustion group (P < 0.05, P < 0.01). Pre-moxibustion at ST 36, CV 12, BL 20 and BL 21 can up-regulate gastric mucosal EGF and TGF-alpha contents and EGFR protein expression in gastric mucosa lesion rats, which may contribute to its effect in relieving stress-induced gastric mucosal injury.

Ou G.-C.,Sun Yat Sen University | Ou G.-C.,Hunan University | Feng X.-L.,Sun Yat Sen University | Lu T.-B.,Sun Yat Sen University
Crystal Growth and Design | Year: 2011

The reaction of a racemic four-coordinated nickel(II) complex [Ni(α-rac-L)](ClO 4) 2 with l-Leu - in acetonitrile/water under basic conditions gave two six-coordinated diastereomers of {[Ni(SS-L)(l-Leu)](ClO 4)} n (Δ-1) and {[Ni(RR-L)(l-Leu)](ClO 4)} n (a-2). While the reaction of [Ni(α-rac-L)](ClO 4) 2 with d-Leu - in acetonitrile/water under basic condition generated two six-coordinated diastereomers of {[Ni(RR-L)(d-Leu)](ClO 4)} n (Λ-1) and {[Ni(SS-L)(d-Leu)](ClO 4)} n (b-2) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, Leu - = leucine anion). Δ-1 and Λ-1 belong to supramolecular stereoisomers in which the [Ni(SS-L)(l-Leu)] + and [Ni(RR-L)(d-Leu)] + monomers are linked through the intermolecular hydrogen bonding interactions to form 1D homochiral right- and left-handed helical chains, respectively, while the connections of [{Ni(RR-L)}(l-Leu)] +/[{Ni(SS-L)}(d-Leu)] + in a-2/b-2 through similar intermolecular hydrogen bonding interactions give 1D zigzag chains instead of 1D helical chains. In contrast, the reactions of [Ni(α-rac-L)](ClO 4) 2 with l/d-leucine in acetonitrile/water under acidic condition gave the left-handed helical chains of {[Ni(SS-L)(l-HLeu)](ClO 4) 2} n (Λ-3) and right-handed helical chains of {[Ni(RR-L)(d-HLeu)](ClO 4) 2} n (Δ-3), respectively, demonstrating the helicity of 1D helical chains is pH dependent The homochiral nature of Δ-1/Λ-1 and a-2/b-2 are confirmed by the results of CD spectra measurements. © 2011 American Chemical Society.

She G.,Hunan University
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2015

The nonlinear vibrations of elastic beam in the state of thermal expansion are analyzed with two-step perturbation method in this paper, Firstly, The non-linear large deflection differential equation of the roller supported beam is established by energy method, then, the nonlinear motion equation is nondimensionalized, and the nonlinear equation is solved by adopting the deflection function compatible to the boundary condition of the beam and by transforming the deflection function to a series of linear differential equations with two-step perturbation method. The higher-order asymptotic solution is obtained. Finally, analysis of example shows that natural frequency of the beam is closely related to the temperature changes and the amplitudes, and the inaccuracy occurred when KBM method is used to analyze the large amplitude vibration in the beam. The results obtained by KBM method proves to be much less accurate than the results presented by two-step perturbation method. ©, 2015, Xi'an Jiaotong University. All right reserved.

Chen Y.,Hunan University
Electronic Journal of Combinatorics | Year: 2010

CF-graphs form a class of multigraphs that contains all simple graphs. We prove a lower bound for the average genus of a CF-graph which is a linear function of its Betti number. A lower bound for average genus in terms of the maximum genus and some structure theorems for graphs with a given average genus are also provided.

Gao T.,Norwegian University of Science and Technology | Wang T.,Hunan University
Crystal Growth and Design | Year: 2010

A one-dimensional (1D) to two-dimensional (2D) topotactic transformation has been proposed for the synthesis of 2D CdS nanosheets by promoting the lateral growth of 1D CdS nanobelts. The as-prepared nanosheets are single crystal with hexagonal structure, usually 20-100 nm in thickness, 20-100 μm in width, and up to several millimeters in length. CdS nanosheets show enhanced multiphonon responses and exciton-phonon couplings, which are correlated to their extraordinary anisotropic geometry. Photoluminescence measurement reveals three emission bands at about 1.61, 2.39, and 2.45 eV, which are attributed to the radiative transitions related to surface states, bandgap, and excitonic molecules, respectively; moreover, the formation of the surface states and the excitonic molecules are significantly enhanced due to the anisotropic geometry of the 2D nanosheets. CdS nanosheets show also pronounced photoconduction under visible light irradiation, indicating potentials in assembly of optoelectronic nanodevices. © 2010 American Chemical Society.

Pang Z.-F.,Henan University | Yang Y.-F.,Hunan University
Image and Vision Computing | Year: 2011

Based on the augmented Lagrangian strategy, we construct a projected gradient algorithm for image restoration and texture extraction. The proposed algorithm is established on the basis of a mixed model which combines the Rudin-Osher-Fatemi (ROF) model with the Lysaker-Lundevold-Tai (LLT) model to reduce the staircase effect and blur phenomenons. The proof of the convergence of the proposed algorithm is provided. Moreover, we show that the dual methods based on convex analysis which have been proposed in some papers can be actually deduced from the augmented Lagrangian strategy. Some numerical examples are supplied to illustrate the efficiency of the proposed algorithm. © 2010 Elsevier B.V. All rights reserved.

To study the effects of Jiawei Huzhang San (JWHZS) decoction on the expressions of the inflammatory factors monocyte chemoattractant protein-1 (MCP-1) and platelet-derived growth factor-BB (PDGF-BB) on experimental autoimmune prostatitis in rats. Twelve male Wistar rats were taken as normal controls, and models of experimental autoimmune prostatitis were established in another 60 by injection of SC purified prostate protein with FCA, and then divided into five groups to be treated with normal saline, indomethacin, high-dose JWHZS (0.445 g/kg), medium-dose JWHZS (0.223 g/kg) and low-dose JWHZS (0.089 g/kg), respectively. All the rats were sacrificed at 30 days after the treatment for detection of the mRNA and protein expressions of inflammatory factors by immunohistochemistry and fluorescent quantitative RT-PCR. In the high-, medium- and low-dose JWHZS groups, the mRNA expressions of MCP-1 (0.31 +/- 0.14, 0.49 +/- 0.21 and 0.62 +/- 0.28) and PDGF-BB (0.50 +/- 0.22, 0.54 +/- 0.17 and 0.71 +/- 0.29), and the protein expressions of MCP-1 (677 +/- 208, 725 +/- 311 and 1302 +/- 884) and PDGF-BB (1265 +/- 698, 1347 +/- 827 and 1655 +/- 812) were significantly lower than in the model control group (MCP-1 mRNA: 1.12 +/- 0.43; MCP-1 protein: 2201 +/- 934; PDGF-BB mRNA: 1.14 +/- 0.51; PDGF-BB protein: 2754 +/- 852) (P < 0.05). And JWHZS exhibited a significantly better activity at high and medium doses than at a low dose (P < 0.05). In the indomethacin control group, both the mRNA and protein expressions of MCP-1 (0.71 +/- 0.34 and 1824 +/- 1157) and PDGF-BB (1.08 +/- 0.37 and 2493 +/- 924) were markedly higher than in the JWHZS groups (P < 0.01). Down-regulation of the inflammatory factors MCP-1 and PDGF-BB may be the important molecular mechanism of JWHZS acting on experimental autoimmune prostatitis.

Yu J.,Fudan University | Yu J.,ZTE Corporation | Dong Z.,Hunan University | Dong Z.,Georgia Institute of Technology | Chi N.,Fudan University
IEEE Photonics Technology Letters | Year: 2011

A novel scheme to generate coherent 21 optical subcarriers with fixed frequency of 25 GHz is proposed and experimentally demonstrated. Using these optical subcarriers, we have successfully generated 1.96 Tb/s (21 × 100 Gb/s) polarization-multiplexing optical orthogonal frequency multiplexed (PM-OFDM) polarization multiplexed quadrature phase-shift keying (QPSK) optical superchannel signal with optical signal-noise ratio of each subchannel larger than 30 dB (0.1-nm bandwidth). We have transmitted this 1.96-Tb/s optical OFDM superchannel over 3200-km SMF-28 with amplification span of 80 km with erbium-doped fiber amplifier-only. © 2011 IEEE.

Lu K.,Shanghai Maritime University | Lu K.,University of Aalborg | Lei X.,Hunan University | Blaabjerg F.,University of Aalborg
IEEE Transactions on Energy Conversion | Year: 2013

The back EMF-based sensorless control method is very popular for permanent magnet synchronous machines (PMSMs) in the medium- to high-speed operation range due to its simple structure. In this speed range, the accuracy of the estimated position is mainly affected by the inductance, which varies at different loading conditions due to saturation effects. In this paper, a new concept of using a constant artificial inductance to replace the actual varying machine inductance for position estimation is introduced. This facilitates greatly the analysis of the influence of inductance variation on the estimated position error, and gives a deep insight into this problem. It also provides a simple approach to achieve a globally minimized position error. A proper choice of the artificial machine inductance may reduce the maximum position error by 50% without considering the actual inductance variation in the control algorithm. Analytical and experimental results are given for validating the proposed theory. © 1986-2012 IEEE.

Embryonic heart development is a very complicated process regulated precisely by a network composed of many genes and signaling pathways in time and space. Forkhead box (Fox, FOX) proteins are a family of transcription factors characterized by the presence of an evolutionary conserved "forkhead"or "winged-helix" DNA-binding domain and able to organize temporal and spatial gene expression during development. They are involved in a wide variety of cellular processes, such as cell cycle progression, proliferation, differentiation, migration, metabolism and DNA damage response. An abundance of studies in model organisms and systems has established that Foxa2, Foxc1/c2, Foxh1 and Foxm1, Foxos and Foxps are important components of the signaling pathways that instruct cardiogenesis and embryonic heart development, playing paramount roles in heart development. The previous studies also have demonstrated that mutations in some of the forkhead box genes and the aberrant expression of forkhead box gene are heavily implicated in the congenital heart disease (CHD) of humans. This review primarily focuses on the current understanding of heart development regulated by forkhead box transcription factors and molecular genetic mechanisms by which forkhead box factors modulate heart development during embryogenesis and organogenesis. This review also summarizes human CHD related mutations in forkhead box genes as well as the abnormal expression of forkhead box gene, and discusses additional possible regulatory mechanisms of the forkhead box genes during embryonic heart development that warrant further investigation. © 2015 Elsevier Ltd. All rights reserved.

Fang F.,Beijing Technology and Business University | Xu J.,Hunan University
Nonlinear Analysis: Real World Applications | Year: 2016

Let Ω be a bounded smooth domain in ℝN with N≥2, C=Ω×(0,∞) and (Formula presented.)(C) be a (P.S.) sequence of the functional (Formula presented.) We study the limit behaviour of un and obtain a global compactness result. © 2015 Elsevier Ltd.

Xiao W.-Z.,Hunan Institute of Engineering | Wang L.-L.,Hunan University
Physica Status Solidi (B) Basic Research | Year: 2014

Using first-principles calculations, we have studied the structural, electronic, and magnetic properties in CdS monolayer doped with nonmagnetic (NM) atoms X (X=B, C, N, and O). The total magnetic moments are about 1.0, 2.0, 1.0, and 0.0μB per supercell for the B-, C-, N-, and O-doped systems, respectively. As the electronegativity of X element increases, the local magnetic moment tends to localize and the impurity states gradually approach the valence band maximum of the host CdS. We find that the CdS monolayer with one S atom per supercell substituted by a B or C atom is half-metallic (HM), while that with an N atom per supercell is a ferromagnetic (FM) semiconductor. As for the one-oxygen doped case, the system still remains a semiconductor. Upon two S atoms per supercell substituted by X (=B, C, and N) atom, the X-doped CdS systems exhibit various magnetic ground states. As a consequence of the competition between double-exchange and super-exchange, the two-B-doped CdS system displays NM and anti-magnetic (AFM) behaviors, while the two-C-doped CdS system shows HM ferromagnetism with a Curie temperature of 280K. However, the two-N-doped CdS system is a semiconductor with weakly AFM ground state. Our study demonstrates that the NM elements doping is an efficient route to tune the magnetic and electronic properties in CdS monolayers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang J.,Hunan University | Katafygiotis L.S.,Hong Kong University of Science and Technology
Structural Safety | Year: 2014

In this paper the problem of reliability-based optimal design of linear structures subjected to stochastic excitations is considered. A global optimization method based on Transitional Markov chain Monte Carlo (TMCMC) is used to address the problem, where the optimization problem is converted into the task of generating sample points (designs) according to a probability density function (PDF) suitably constructed on the feasible space of designs satisfying all the constraints. TMCMC is used for generating sample points, in order to get higher convergence rate of the stationary distribution of the Markov chain states to the constructed PDF. The generation of sample points uniformly distributed in the feasible space, which is required at the initial stage of TMCMC, is achieved by using Subset Simulation. To apply Subset Simulation and TMCMC in the concerned reliability-based optimization problem, Domain Decomposition Method (DDM) is used to examine the reliability constraint, that is, whether the failure probability at a given design exceeds a specified threshold. Based on the statistical properties of the failure probability estimator given by DDM, a 'minimum' computational effort, in terms of providing a reliable judgment on the reliability constraint, is defined so that a further reduction in the computational cost can be achieved in the proposed reliability-based optimization (RBO) algorithm. Illustrative examples are presented to show the application and the advantages of the proposed global RBO algorithm. © 2014 Elsevier Ltd.

Zhu P.,Hunan University | Zhang L.W.,Shanghai Ocean University | Liew K.M.,City University of Hong Kong
Composite Structures | Year: 2014

A meshless local Petrov-Galerkin approach based on the moving Kriging interpolation technique is developed for geometrically nonlinear thermoelastic analysis of functionally graded plates in thermal environments (prescribed a temperature gradient or heat flux). The Kriging interpolation method makes the constructed shape functions possess Kronecker delta function property and thus special techniques for enforcing essential boundary conditions are avoided. In the thermal analysis, the dependency of thermal conductivity of functionally graded materials on temperature is involved, which gives rise to a nonlinear partial differential heat conduction equation. The nonlinear formulation of large deflection of the functionally graded plates is based on the first-order shear deformation plate theory in the von Kármán sense by taking small strains and moderate rotations into account. The incremental form of nonlinear equations is obtained by Taylor series expansion and the tangent stiffness matrix is explicitly developed in two different ways within the framework of the local meshless method. The nonlinear solutions are computed using the Newton-Raphson iteration method. Parametric and convergence studies are conducted to examine the stability of the proposed method and then several selected numerical examples are presented to demonstrate the accuracy and effectiveness of the method for nonlinear bending problems of functionally graded plates in thermal environments. © 2013 Elsevier Ltd.

Zhong F.,Hunan University
International Journal of Theoretical Physics | Year: 2014

We investigate the quantum discord dynamics of a two-qubit system coupled to an XY spin-chain environment with energy current. We compared dynamical behaviors of quantum discord under different system-environment couplings, the size of the degrees of freedom of the environment, the anisotropy parameter, and the energy current. The results indicate that the energy current can strongly suppress the quantum discord in the weak-coupling region, while it has no obvious effect on the quantum discord in the strong-coupling regime. © 2013 The Author(s).

Hu D.,Hunan University | Li Q.,Hunan Normal University
IEEE Communications Letters | Year: 2010

In asymmetric fingerprinting, the merchant can trace the traitors from a pirated copy by means of the embedded unique fingerprint, while the customer is immune of being framed due to the asymmetric property. In this letter, we propose an asymmetric fingerprinting scheme based on 1-out-of-n oblivious transfer (OT1n), which is efficient from the bandwidth usage point of view. First, multicast that is an efficient transport technology for one-to-many communication is exploited, which can reduce the bandwidth usage significantly. Second, symmetric encryption instead of public-key encryption is performed on the multimedia content, which also can reduce the complexity and communication cost. © 2010 IEEE.

Zhu H.,Hunan University
Oncology Reports | Year: 2014

Deregulation of forkhead box (FOX) proteins has been found in many genetic diseases and malignancies including leukemia. Leukemia is a common neoplastic disease of the blood or bone marrow characterized by the presence of immature leukocytes and is one of the leading causes of death due to cancer. Forkhead transcription factors, FOXM1 and FOXO family members (FOXOs), are important mediators in leukemia development. Aberrant expression of FOXM1 and FOXOs results in leukemogenesis. Usually the expression of FOXM1 is upregulated, whereas the expression of FOXOs is downregulated due to phosphorylation, nuclear exclusion and degradation in leukemia. On the one hand, FOXOs are bona fide tumor suppressors, on the other hand, active FOXOs maintain leukemia stem cells and stimulate drug resistance genes, contributing to leukemogenesis. FOXM1 and FOXOs have been proven to be potential targets for the development of leukemia therapeutics. They are also valuable diagnostic and prognostic markers in leukemia for clinical applications. This review summarizes the present knowledge concerning the molecular mechanisms by which FOXM1 and FOXOs modulate leukemogenesis and leukemia development, the clinical relevance of these FOX proteins in leukemia and related areas that warrant further investigation.

Zhang Z.,Hunan University | Zhou D.,Yunnan University
Journal of the Franklin Institute | Year: 2010

In this paper, a discrete-time interval general BAM bidirectional associative memory neural networks model is considered. By employing the theory of coincidence degree and using Halanay-type inequality technique we establish new sufficient conditions ensuring the existence and global exponential stability of periodic solutions for the discrete-time interval general BAM bidirectional neural networks. The results obtained generalize and improve known results in [23]. An example is provided to show the correctness of our analysis. © 2010 The Franklin Institute.

He F.Y.,Hunan University
Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica | Year: 2012

Injections for traditional Chinese medicine have over 60 years of history of development and application. In recent years, however, their adverse reactions have been reported one after another. Consequently, studies on screening sensitinogens (sensibiligens) from injections for traditional Chinese medicine have drawn people's attention and become a tough problem all over the world. This essay analyzes the current state of studies on screening techniques of sensitinogens in injections for traditional Chinese medicine according their mechanism of immunotoxicity, and then proposes to adopt the synthetic immunoassay combining immunity bottle chip, immunity cover chip and immunity chromatographic fingerprint to screen sensitinogens from injections for traditional Chinese medicine, in order to build a safety evaluation barrier for development and clinical application of injections for traditional Chinese medicine.

Mao X.,Central China Normal University | Su H.,Central China Normal University | Tian D.,Central China Normal University | Li H.,Central China Normal University | Yang R.,Hunan University
ACS Applied Materials and Interfaces | Year: 2013

1,2-bis-(2-pyren-1-ylmethylamino-ethoxy) ethane (NPEY) was synthesized and brought to the surface of graphene nanosheets (GNs) via π-π stacking, which provided a simple and convenient route for processing "turn-on" fluorescent sensor by simply mixing the diluted aqueous solutions of both components. The synthesized NPEY modified graphene nanosheets (NPEY-GNs) not only allows good selectivity toward Mn2+ with the detection limit of 4.6 × 10-5 M, but also shows "turn-on" response for Mn2+ both in vitro and in living cells. These sensing capabilities of NPEY-GNs in living cells make it a robust candidate for many biological fields, such as intracellular tracking, intracellular imaging, etc. © 2013 American Chemical Society.

Yuan Z.K.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2012

To explore the function and target pathway of the correlated differential gene of coronary heart disease (CHD) of blood stasis syndrome (BSS). Patients of the genealogical CHD of BSS (group A) and the genealogical CHD of non-BSS (group B), the genealogical non-CHD of BSS (group C), the genealogical healthy subjects (group D), the non-genealogical CHD of BSS (group E), the non-genealogical healthy subjects (group F) were recruited in this study. The differential gene expression spectrums were studied using gene chip technique. The molecular functions of differential genes were analyzed and illustrated by gene ontology (GO) analysis. The differential gene pathways were found out at BioCarta and KEGG. The meaningful target pathways were screened by hypergeometric distribution statistical method. The differential genes were verified using Real-time fluorescent quantitative PCR. (1) By screening the gene chip data (with FC > or =3), we found the expressions of differential genes of CHD of BSS were mainly involved in chemokine, interleukin cytokine, alexin system, matrix metal proteinase system, fibroblastic growth factor, endothelial cell adhesion molecule, and so on. (2) By GO analysis of related differential genes (P < 0.05), we found the molecular functions of differential genes associated with CHD BSS. (3) By BioCarta and KEGG pathway analysis, we found the target pathways of the hereditary correlated differential genes of CHD BSS with significance were mainly involved in inflammation, plaque formation, endothelial injury, and so on. The results of Real-time fluorescent quantitative RT-PCR proved the accuracy of the gene chip. The hereditary correlated differential genes of CHD BSS were closely associated with inflammation, plaque formation, and endothelial injury.

Grimes C.A.,KMG2 Sensors Corporation | Roy S.C.,Indian Institute of Technology Madras | Rani S.,Pennsylvania State University | Cai Q.,Hunan University
Sensors | Year: 2011

Thick-film magnetoelastic sensors vibrate mechanically in response to a time varying magnetic excitation field. The mechanical vibrations of the magnetostrictive magnetoelastic material launch, in turn, a magnetic field by which the sensor can be monitored. Magnetic field telemetry enables contact-less, remote-query operation that has enabled many practical uses of the sensor platform. This paper builds upon a review paper we published in Sensors in 2002 (Grimes, C.A.; et al. Sensors 2002, 2, 294-313), presenting a comprehensive review on the theory, operating principles, instrumentation and key applications of magnetoelastic sensing technology. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Peng Q.H.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2012

To observe the effects of the extract of Buddleja officinalis eye drops (EBOED) on basic tears secretory volume, tear film stability, and expressions of androgen receptors (AR) in castrated rats with dry eye, and to investigate the mechanism of EBOED on dry eye caused by decreased anti-androgen levels. Forty-five male Wistar rats were randomly divided into the blank group, the model group, and the treatment group (treated by EBOED), respectively. Rats in each group were further divided into three sub-groups (fed for one month, two months, and three months, respectively). There were totally nine groups, with five in each. The dry eye model was established with orchiectomy of rats in the model group and the treatment group. EBOED was given to rats in the treatment group for one successive month. Schirmer I test (SIT) and breakup time of tear film (BUT) were determined in all experimental rats. Expressions of AR was analyzed by flow cytometer. Ths SIT value, BUT, and AR positive rate in the model group at the 1st, 2nd, 3rd month were lower than those in the blank group of the same time points (P < 0.01). There was statistical difference in SIT value, BUT, and AR positive rate between the model group and the treatment group at the three time points (P < 0.01). Take the three-month subgroup as an example, the SIT value in the treatment group was (12.667 +/- 5.221) mm, obviously higher than that in the model group (2.676 +/- 1.987) mm. The BUT in the treatment group was (11.758 +/- 4.415) s, obviously longer than that of the model group (4.667 +/- 2.108) s. The AR positive rate in the treatment group was 49.33% +/- 3.44%, obviously higher than that of the model group (33.32% +/- 7.12%, all P < 0.01). The main components of EBOED was the flavonoids which could significantly inhibit the occurrence of dry eye in rats with decreased androgen levels. Its mechanism might possibly be similar to androgen.

Zhang T.,Hunan University
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012

The occurrence of off-flavor problems caused by prokaryotes cyanobacteria and actinomycetes is a worldwide water and food quality issue. Based on literatures on two earthy-muddy-smelling metabolites, (i. e., geosmin and 2-methylisoborneol (2-MIB)), we reviewed their chemical characteristics, biosynthetic pathways, genes and enzymes that are involved in biosynthesis. Then we discussed current research questions related to off-flavor and future directions. Finally, we addressed the significance of probable key regulatory mechanism for the production and release of geosmin and 2-MIB, which could provide more scientific strategies to better control off-flavors outbreaks in drinking and aquaculture water.

Zhu H.-Y.,Taizhou University | Zhu H.-Y.,Hubei University | Fu Y.-Q.,Taizhou University | Jiang R.,Taizhou University | And 3 more authors.
Bioresource Technology | Year: 2012

Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads (m-CS/PVA HBs) were prepared by an instantaneous gelation method and characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). Results of characterization indicated that m-CS/PVA HBs have been prepared successfully without damaging the crystal structure of Fe 3O 4 and their saturation magnetization were about 21.96emug -1. The adsorption capacity of Congo Red on the m-CS/PVA HBs was 470.1mgg -1. The adsorption was well described by pseudo-second-order kinetics and Langmuir equation. Positive value of enthalpy change (ΔH °) (13.32kJmol -1) showed that the adsorption was endothermic and physical in nature. The values of Gibbs free energy change (ΔG °) were found to be -3.321kJmol -1 at 298K for m-CS/PVA HBs, indicating the spontaneity of Congo Red adsorption. Therefore, the m-CS/PVA HBs could be employed as a low-cost alternative to other adsorbents in the removal of dyes from aqueous solution. © 2011 Elsevier Ltd.

Li Z.,CAS Beijing National Laboratory for Molecular | He X.,CAS Beijing National Laboratory for Molecular | Wang Z.,CAS Beijing National Laboratory for Molecular | Yang R.,Hunan University | And 2 more authors.
Biosensors and Bioelectronics | Year: 2015

A new near-infrared fluorescence off-on probe is developed and applied to fluorescence imaging of nitroreductase in zebrafish in vivo. The probe is readily prepared by connecting 4-nitrobenzene as a quenching and recognizing moiety to a stable hemicyanine skeleton that can be formed via the decomposition of IR 780. The fluorescence off-on response of the probe to nitroreductase is based on the enzyme-catalyzed reduction of the 4-nitrobenzene moiety, followed by the 1,6-rearrangement-elimination and the fluorophore release. Compared with the existing nitroreductase probes, the proposed probe exhibits superior analytical performance such as near-infrared fluorescence emission over 700. nm as well as high selectivity and sensitivity, with a detection limit of 14. ng/mL. More importantly, the probe has been successfully applied to visualize the distribution of nitroreductase in living zebrafish in vivo, revealing that nitroreductase might mainly exist in zebrafish yolk sac. The superior properties of the probe make it of great potential use in other biosystems and in vivo studies. © 2014 Elsevier B.V.

Yao L.Y.,China Automotive Engineering Research Institute Co. | Yu D.J.,Hunan University | Zhou J.W.,China Automotive Engineering Research Institute Co.
Applied Acoustics | Year: 2012

This paper addresses the cell-based smoothed radial point interpolation method (CS-RPIM) for 2D acoustic problem. In present method, the acoustic domain is discretized using triangular background cells, and each cell is further divided into several smoothing cells and then the cell-based gradient smoothing operation is implemented through the smoothing cells. The pressure field function is approximated using RPIM shape functions. Supporting node selection for shape function construction uses the T2L-scheme associated with edges of the background cells. The system equations are derived using the smoothed Galerkin weak form, and the essential boundary conditions are imposed directly as in the finite element method (FEM). The cell-based gradient smoothing operation provides proper softening effect, makes the CS-RPIM model much softer than the "overly-stiff" FEM model and hence significantly reduces the numerical dispersion error. Numerical results show that the CS-RPIM achieves more accurate results and higher convergence rates as compared with the corresponding finite elements © 2012 Elsevier Ltd. All rights reserved.

Zhu H.-M.,Hunan University | Li S.-F.,Shihezi University | Yu K.,Shihezi University | Yu K.,Brunel University
Energy Economics | Year: 2011

This paper proposes a panel threshold cointegration approach to investigate the relationship between crude oil shocks and stock markets for the OECD and non-OECD panel from January 1995 to December 2009. Nonlinear cointegration is confirmed for the oil-stock nexus in the panel. Because threshold cointegration is found, the threshold vector error correction models can be run to investigate the presence of asymmetric dynamic adjustment. The Granger causality tests demonstrate the existence of bidirectional long-run Granger causality between crude oil shocks and stock markets for these OECD and non-OECD countries. However, the short-run Granger causality between them is bidirectional under positive changes in the deviation and unidirectional under negative ones. Moreover, the speed of adjustment toward equilibrium is faster under negative changes in the deviation than that under positive ones in these OECD and non-OECD countries. © 2011 Elsevier B.V.

Tian F.,Zhoukou Normal University | Liu Y.,Hunan University
Scripta Materialia | Year: 2013

The successful fabrication of p-type nickel oxide (NiO)/n-type zinc oxide (ZnO) heterostructures was achieved by growing NiO nanoparticles on ZnO hierarchical structures. Flower-like ZnO was developed by chemical bath deposition and used as a support to grow cubic NiO particles. The photocatalytic activity of the as-obtained heterostructures for the degradation of methyl orange was much higher than that of pure NiO, ZnO and their physical mixture, which could be ascribed to the formation of p-n heterojunctions. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Ke S.,Hunan University
Annals of Regional Science | Year: 2010

This paper investigates the causal relationship between, and the determinants of, urban labor productivity and industrial agglomeration across Chinese cities. We extend the Ciccone and Hall (Am Econ Rev 86(1):54-70, 1996) production density model by distinguishing between the size of the industrial sector and the density of the urban economy in order to examine the effects of industry agglomeration and congestion on urban productivity. We also account for the endogeneity of industrial agglomeration and propose a simultaneous equation model to estimate the determinants of urban productivity and agglomeration. A spatial econometric analysis across 617 Chinese cities in year 2005 shows that the spatial concentration of industrial production is an important cause of higher productivity in large industrial cities and cities in neighboring regions, where higher productivity resulting from concentrated industrial production then leads to further agglomeration in these cities. Controlling for the size of the industrial sector, employment density has a negative effect on urban productivity. We conclude by briefly discussing potential policy implications of the empirical findings. © Springer-Verlag 2009.

Wang S.J.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2012

To study the main mechanisms of Aitongxiao Recipe (ATXR) for anti-tumor at the molecular level, and to clarify different efficient drugs' roles in anti-tumor, thus in-depth explaining the objectivity and substance of "cancer toxic" theory. Walker-256 tumor strain was used for Wistar rat transplanted liver cancer modeling. After successful modeling rats were randomly divided into 5 groups, i. e., the ATXP group, the qi regulating and blood circulating group (as the assembled I group), the heat clearing and detoxification group (as the assembled II group), the body resistance strengthening and cultivating group (as the assembled III group), and the model group, 10 in each group. Corresponding medication was given to rats in each group for 14 successive days. Finally rats were sacrificed and the tumor mass was taken out. The apoptosis rate and the cell cycle of tumor cells were detected by flow cytometry Annexin V/PI. The protein and mRNA expressions of Bcl-2 and survivin were detected using immunohistochemistry and real-time fluorescent quantitative PCR. (1) The apoptosis of hepatoma carcinoma cells could be obviously promoted in the ATXP group. The cell cycle could also be affected, making major cells arrest at G0/G1 phase. The proliferation of hepatoma carcinoma cells was effectively prevented. The efficacy in the assembled II group was in line with that in the ATXP group with no statistical difference (P>0.05). It was also effective in the assembled III group, but its efficacy was not as good as that in the former two groups, showing statistical difference (P<0.01). (2) ATXP could obviously down-regulate the protein and mRNA expressions of Bcl-2 and survivin in hepatoma carcinoma cells. Drugs for heat clearing and detoxification showed significant effects on down-regulating the protein and mRNA expressions of Bcl-2 and survivin in hepatoma carcinoma cells. Their effects were similar to that of ATXP (P>0.05). The effects of drugs for body resistance strengthening and cultivating were not as good as the former two, showing statistical difference (P<0.01). Drugs for blood circulating and stasis removing could up-regulate the protein and mRNA expressions of Bcl-2 and survivin to some extent. (1) ATXP could increase the apoptosis ratio of hepatoma carcinoma cells obviously through down-regulating the protein and mRNA expressions of Bcl-2 and survivin, thus inhibiting their proliferation. (2) Drugs for heat clearing and detoxification played the most important roles in ATXP. The evil heat and dampness (damp-heat insidious pathogen) is the most fundamental carcinogenic factors. The insufficiency of vital qi is also one of the pathogenic factors. The mechanisms of phlegm, stasis, and other pathological products are not clear and await further studies.

Pan J.,Hunan University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2012

To observe the effect of Electroacupuncture (EA) of "Quze" (PC 3) and "Neiguan" (PC 6) on cerebral angiogenesis in cerebral ischemia (CI) rats, so as to research its mechanisms underlying improvement of stroke. Fifty SD rats were randomized into normal control, sham, model, EA-PC 3-PC 6, and EA-Hegu (LI 4)-Quchi (LI 11) groups. CI model was established by occlusion of the middle cerebral artery. EA (2-4 V, 20 Hz) was applied to PC3, PC6, LI 4 and LI 11 respectively 6 h, 24 h, 48 h and 72 h after modeling, 30 min for each time. Serum vascular endothelial growth factor (VEGF) content was assayed by enzyme linked immunosorbent assay (ELISA), and cerebral VEGF immunoactivity was detected by immunohistochemistry. Compared to the normal control group, serum VEGF content, cerebral VEGF expression level, and the number of VEGF-positive microvessels in the ischemic cerebral region in the model, EA-PC 3-PC 6 and EA-LI 4-LI 11 groups were increased significantly (P<0.01). In comparison with the model group, serum VEGF content, cerebral VEGF expression level, and the number of VEGF-positive microvessels in the EA-LI 4-LI 11 and EA-PC 3-PC 6 groups were up-regulated further (P<0.01), and the effects of the EA-PC 3-PC 6 group were obviously superior to those of the EA-LI4-LI 11 group in up-regulating VEGF expression and the number of VEGF-positive microvessels (P<0.01). No significant difference was found between the EA-LI 4-LI 11 and EA-PC 3-PC 6 groups in serum VEGF levels (P>0.05). EA of acupoints of both Large Intestine Meridian and Pericardium Meridian can up-regulate serum VEGF, cerebral VEGF expression and the number of VEGF-positive microvessels in CI rats, suggesting an increase of cerebral angiogenesis after the treatment. The effect of EA-PC 3-PC 6 is markedly superior to that of EA-LI 4-LI 11.

Jian W.X.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2012

To find out the metabolite profile of rats' myocardial tissue of cardiac blood stasis syndrome (CBSS), and to analyze the metabolic pathway of CBSS rats' myocardial tissue by observing the changes of phenotypes intervened by Yangxin Tongmai Recipe (YTR). Acute myocardial infarction (AMI) rat model of CBSS was prepared by ligating the left anterior descending coronary artery. Meanwhile, the model was interfered with YTR. The metabolites of rats' myocardial tissue were detected in the model group, the YTR group, the sham-operation group, and the blank control group using GC-MS (8 rats in each group). Changes of metabolite contents were analyzed among different groups using principal component analysis (PCA) and least-square analysis. As for PCA: The results of PCA showed that principal component integral (PCI) of the four groups was mainly distributed in the three regions of oval scatterplot. The factor loading gram showed that contents of glycine, fumaric acid, malic acid, glutamic acid, glucose, phosphoric acid, galactopyranose, lysine were changed in the model group. Analysis of partial least square method: PLS regression model showed that obvious linear correlation existed between the model group and the YTR group, which proved the model was reasonably established. The drug intervention was highly positively correlated with glycine, malic acid, glutamic acid, glucose, highly correlated with urea and butanedioic acid, but negatively correlated with lysine. According to VIP value, each variable was closely correlated with the drug intervention in sequence as malic acid, glutamic acid, glycine, glucose, fumaric acid, urea, galactose, tyrosine, lactic acid, and alanine. Results of variability analysis: Obvious changed variability analysis of metabolite difference showed that 10 metabolites such as glycine, etc. obviously decreased in the model group, showing significant difference when compared with the normal group (P<0.01). Compared with the model group, contents of glycine, fumaric acid, malic acid, glutamic acid, glucose, tyrosine,urea, lactic acid, and alanine, etc. obviously increased after drug intervention (P<0.01). Of them, the increment of malic acid, glumatic acid, tyrosine, and urea was less, showing significant difference when compared with that of the normal group. The mean of lysine was slightly lowered after drug intervention, but with insignificant difference when compared with that of the model group. AMI rats of CBSS was closely correlated with myocardial metabolites such as malic acid, glutamic acid, glycine, glucose, fumaric acid, urea, galactopyranose, lactic acid, alanine, and tyrosine, etc. The metabolite profile of rats' myocardial tissue showed AMI rat model of CBSS was closely correlated with post-hypoxia glucose metabolism disorder. YTR could effectively intervene this process.

Tan Z.W.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2012

To study the effects of Qingxin Kaiqiao Recipe (QKR) saponin on the expressions of Bax, Bcl-2, beta-amyloid (Abeta), and beta-amyloid precursor protein (betaAPP) in the cortex and hippocampus of Alzheimer's disease (AD) rats. Thirty-two SD rats of SPF grade were selected. Abeta 25 - 35 was injected into the bilateral amygdala to prepare the AD model. After modeling rats were randomly divided into the model group, the donepezil hydrochloride group (Donepezil Hydrochloride Tablet, 1.67 mg/kg), the QLR group (QLR Decoction, 12.67 mL/kg), and the saponin group (saponin, 6.30 mg/kg), 8 rats in each group. Another 8 rats were selected as the normal group. Rats in the normal group and the model group were given with equal volume of double distilled water by gastrogavage. The intervention was performed once daily for 2 successive weeks. The Morris water maze test was carried out by the end of medication. The escape latency and the platform crossing times were recorded during the 1 -5 days. The expressions of Bax, Bcl-2, Abeta, and betaAPP in the cortex and hippocampus were detected using immunohistochemical assay. Compared with the model group, the 3rd - 5th day escape latency were all shortened in each medication group. The expressions of Bax, Abeta, and betaAPP decreased in the cortex and hippocampus. The numbers of platform crossing increased. The expression of Bcl-2 in the cortex increased. The expression of Bcl-2 in the hippocampus increased in the donepezil hydrochloride group and the QLR group with statistical difference (P<0.01, P<0.05). Compared with the donepezil hydrochloride group, the expression of betaAPP increased in the cortex and hippocampus of the saponin group. The expression of Abeta in the cortex and hippocampus decreased, the expression of Bax in the hippocampus decreased, and the expression of Bcl-2 in the cortex increased in the QLR group. The escape latency was obviously postponed at day 3 -5, the platform crossing times decreased, the expression of Bcl-2 in the cortex and hippocampus decreased in the saponin group, showing statistical difference (P<0.05, P<0.01). QKR could significantly improve AD rats' learning, memory, and spatial capabilities, which might be achieved through decreasing the expressions of Bax, Abeta, and betaAPP in the cerebral cortex and hippocampus, and elevating the expression of Bcl-2.

Wang X.-J.,Henan Normal University | Wang W.,Henan Normal University | Liu Y.-L.,Hunan University
Sensors and Actuators, B: Chemical | Year: 2012

ZnO flowers functionalized by Au nanoparticles (NPs) with various Au contents have been developed. The gas sensing properties of the sensors fabricated from these materials were examined and compared at varied working temperatures. Improved sensor response, selectivity and short response and recovery times to acetone vapor were achieved by suitably modulating the weight percent of Au NPs. Experimentally, the formation of Au/ZnO hybrids and surface coarsening of ZnO flowers were found to lead to apparent further enhancement of the sensor performance. © 2012 Elsevier B.V.

Choi K.-K.,City of Los Angeles | Choi K.-K.,University of Southern California | Xiao Y.,University of Southern California | Xiao Y.,Hunan University
Journal of Composites for Construction | Year: 2010

This study intends to provide a simplified analytical model of the laterally confined concrete filled steel tube (CCFT) column system which adopts carbon-fiber-reinforced polymer (CFRP) jackets in order to make up for major defects of the traditional concrete filled steel tube (CFT) column system. This CCFT analytical model, by adding one additional parameter for CFRP confinement to the CFT column analytical solution, is greatly simplified and expedites the analytical processes to explain the stress-strain relationship of the CCFT column system. In the study, several types of the CCFT column systems with different parameters are analyzed by the proposed simplified analytical model and its associated numerical program (USC-CFT). To verify the accuracy of the analytical model, this study compares the load-strain relationship calculated by USC-CFT both to the experimental results conducted by the traditional method and to the results calculated by the computer-aided finite element method (FEM) analysis method. This study shows equilibrium conditions, deformation compatibilities, constitutive models, and an analysis procedure used in the proposed simplified analytical solution and presents finite element models and analysis procedure used in FEM analysis. © 2010 ASCE.

Li Q.S.,City University of Hong Kong | Zhi L.,Hunan University | Hu F.,CAS Institute of Atmospheric Physics
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2010

This paper is concerned with vertical distributions of mean wind speed and atmospheric turbulence characteristics over a typical urban area. The wind data were measured from more than 30 anemometers installed at 15 different height levels on the 325. m high Beijing Meteorological Tower during numerous windstorms. Profiles of mean wind speed are presented based on the field measurements and are compared with empirical models' predictions. Aerodynamic parameters of atmospheric boundary layer are determined from the measured wind speed profiles. Furthermore, wind velocity data in longitudinal, lateral and vertical directions, which were recorded by ultrasonic anemometers at three height levels during windstorms, are analyzed and discussed. Atmospheric turbulence information such as turbulence intensity, gust factor, turbulence integral length scale and power spectral densities of the three-dimensional fluctuating wind velocity are presented and used to evaluate the adequacy of the existing theoretical and empirical models. A comparative study between the measured profiles of turbulence parameters and those estimated by AIJ-RLB-1996 and ASCE (1999) is performed. The objective of this study aims to provide useful information on boundary layer wind characteristics for the wind-resistant design of tall buildings and high-rise structures in urban areas. © 2010 Elsevier Ltd.

Liu Y.,Wenzhou University | Yao B.,Wenzhou University | Deng C.-L.,Wenzhou University | Tang R.-Y.,Wenzhou University | And 2 more authors.
Organic Letters | Year: 2011

Chemical equations presented. A new, simple method for selectively synthesizing alkyl aryl ketones has been developed by palladium-catalyzed oxidative coupling of trialkylamines with aryl iodides. In the presence of PdCl2(MeCN)2, TBAB, and ZnO, a variety of aryl iodides underwent an oxidative coupling reaction with tertiary amines and water to afford the corresponding alkyl aryl ketones in moderate to excellent yields. It is noteworthy that this method is the first example of using trialkylamines as the carbonyl sources for constructing alkyl aryl ketone skeletons. © 2011 American Chemical Society.

Mu Y.,Zhejiang Normal University | Jia D.,Zhejiang Normal University | He Y.,Zhejiang Normal University | Miao Y.,Zhejiang Normal University | And 2 more authors.
Biosensors and Bioelectronics | Year: 2011

Development of fast and sensitive sensors for glucose determination is important in food industry, clinic diagnostics, biotechnology and many other areas. In these years, considerable attention has been paid to develop non-enzymatic electrodes to solve the disadvantages of the enzyme-modified electrodes, such as instability, high cost, complicated immobilization procedure and critical operating situation et al. Nano nickel oxide (NiO) modified non-enzymatic glucose sensors with enhanced sensitivity were investigated. Potential scanning nano NiO modified carbon paste electrodes up to high potential in alkaline solution greatly increases the amount of redox couple Ni(OH)2/NiOOH derived from NiO, and thus improves their electrochemical properties and electrocatalytical performance toward the oxidation of glucose. The non-enzymatic sensors response quickly to glucose and the response time is less than 5s, demonstrating excellent electrocatalytical activity and assay performance. The calibration plot is linear over the wide concentration range of 1-110μM with a sensitivity of 43.9nA/μM and a correlation coefficient of 0.998. The detection limit of the electrode was found to be 0.16μM at a signal-to-noise ratio of 3. The proposed non-enzymatic sensors can be used for the assay of glucose in real sample. © 2010 Elsevier B.V.

Huo J.,University of Southampton | Huo J.,Hunan University | Aguilera-Sigalat J.,University of Southampton | El-Hankari S.,University of Southampton | Bradshaw D.,University of Southampton
Chemical Science | Year: 2015

In this contribution we report a synthetic strategy for the encapsulation of functional biomolecules within MOF-based microcapsules. We employ an agarose hydrogel droplet Pickering-stabilised by UiO-66 and magnetite nanoparticles as a template around which to deposit a hierarchically structured ZIF-8 shell. The resulting microcapsules are robust, highly microporous and readily attracted to a magnet, where the hydrogel core provides a facile means to encapsulate enzymes for recyclable size-selective biocatalysis. © The Royal Society of Chemistry 2015.

Chang H.,Tsinghua University | Tang L.,Tsinghua University | Wang Y.,Tsinghua University | Jiang J.,Hunan University | Li J.,Tsinghua University
Analytical Chemistry | Year: 2010

Combining nanomaterials and biomolecule recognition units is promising in developing novel clinic diagnostic and protein analysis techniques. In this work, a highly sensitive and specific fluorescence resonance energy transfer (FRET) aptasensor for thrombin detection is developed based on the dye labeled aptamer assembled graphene. Due to the noncovalent assembly between aptamer and graphene, fluorescence quenching of the dye takes place because of FRET. The addition of thrombin leads to the fluorescence recovery due to the formation of quadruplex-thrombin complexes which have weak affinity to graphene and keep the dyes away from graphene surface. Because of the high fluorescence quenching efficiency, unique structure, and electronic properties of graphene, the graphene aptasensor exhibits extraordinarily high sensitivity and excellent specificity in both buffer and blood serum. A detection limit as low as 31.3 pM is obtained based on the graphene FRET aptasensor, which is two orders magnitude lower than those of fluorescent sensors based on carbon nanotubes. The excellent performance of FRET aptasensor based on graphene will also be ascribed to the unique structure and electronic properties of graphene. © 2010 American Chemical Society.

Yuan Z.,Hunan University | Zou X.,University of Western Ontario
Mathematical Biosciences and Engineering | Year: 2013

We consider a mathematical model that describes the interactions of the HIV virus, CD4 cells and CTLs within host, which is a modification of some existing models by incorporating (i) two distributed kernels reecting the variance of time for virus to invade into cells and the variance of time for invaded virions to reproduce within cells; (ii) a nonlinear incidence function f for virus infections, and (iii) a nonlinear removal rate function h for infected cells. By constructing Lyapunov functionals and subtle estimates of the derivatives of these Lyapunov functionals, we shown that the model has the threshold dynamics: if the basic reproduction number (BRN) is less than or equal to one, then the infection free equilibrium is globally asymptotically stable, meaning that HIV virus will be cleared; whereas if the BRN is larger than one, then there exist an infected equilibrium which is globally asymptotically stable, implying that the HIV-1 infection will persist in the host and the viral concentration will approach a positive constant level. This together with the dependence/ independence of the BRN on f and h reveals the effect of the adoption of these nonlinear functions.

Chen Z.,Hunan University | Lovett D.,Daresbury Innovation Center | Morris J.,Newcastle University
Journal of Process Control | Year: 2011

Process analytical technologies (PAT) are increasingly being explored and adopted by pharmaceutical and industrial biotechnology companies for enhanced process understanding, Quality by Design (QbD) and Real Time Release (RTR). To achieve these aspirations there is a critical need to extract the most information, and hence understanding, from complex and often 'messy' spectroscopic data. This contribution reviews a number of new approaches that have been shown to overcome the limitations of existing calibration/modelling methodologies and describes a practical system which would enhance robustness of the closed loop process control system and overall 'control strategy'. Application studies are described of the use of on-line spectroscopy for the monitoring and control of a downstream solvent recovery column, batch cooling crystallization and pharmaceutical fermentation. © 2011 Elsevier Ltd. All rights reserved.

Peng X.-F.,Central South University of forestry and Technology | Wang X.-J.,Central South University of forestry and Technology | Gong Z.-Q.,Central South University of forestry and Technology | Chen K.-Q.,Hunan University
Applied Physics Letters | Year: 2011

We investigate phonon transport and thermal conductance in a Graphene Nanoribbon modulated with a double-cavity quantum structure at low temperatures. Two methods are compared: the force-constant and elastic wave continuum models. Calculations show that both the models show the similar thermal conductance property at low temperatures despite the excited theory of the discrete phonon modes in quantum structure being not the same. However, in the higher temperature region, the thermal conductance in the force-constant model is bigger than that in the elastic wave continuum model. The difference originates from the inequable cutoff frequencies of the phonon modes. A brief analysis of these results is given. © 2011 American Institute of Physics.

Li Z.,Guangxi University for Nationalities | Xie T.,Guangxi University | Li Q.,Hunan University
Computers and Mathematics with Applications | Year: 2012

In this paper, we investigate some properties of (X, τθ) such as compactness, separate property, Lindelf property and connectedness, where (X, τθ) is induced by a reflexive relation θ on X which may be infinite. Moreover, we introduce the concept of approximating spaces and research their characterizations and properties. Particularly, we obtain a sufficient and necessary condition that topological spaces are approximating spaces. These will be not only conducive to better understanding basic concepts and properties of a rough set, but also have theory and actual significance to topology. © 2012 Published by Elsevier Ltd.

To compare the clinical efficacy differences among acupuncture at special acupoints, nonspecific acupoints and non acupoints in Foot Yangming Meridian for functional dyspepsia (FD) at different time points. One hundred and sixteen FD patients were randomly divided into a special acupoints in Foot Yangming Meridian group (group A, n = 36), a non-specific acupoints in Foot Yangming Meridian group (group B, n 39) and a non acupoints group (group C, n = 41). Group A was treated with acupuncture at Chongyang (ST 42), Fenglong (ST 40), Zusanli (ST 36) and Liangqiu (ST 34), and group B was treated with acupuncture at Tiaokou (ST 38), Yinshi (ST 33), Futu (ST 32) and Dubi (ST 35), and the assisted acupoints were setting up at 2 mm apart from selected acupoints in meridian of proximal part. Group C was treated with 4 non acupoints: (1) medial elbow, middle point on the line between olecranon and armpit; (2) middle point on the line between condylus medialis humeri and wrist of elbow-bone; (3) the junction of deltoid and biceps inside the arm; (4) 1-2 cm horizontally away from Zusanli (ST 36), lateral border of shin bone, and the assisted acupoints were setting up at 2 mm away from selected non acupoints along limb longitudinal axis of proximal part. All acupoints and assisted acupoints were connected to the HANS nerve stimulator and they were all treated for 4 courses. The FD Symptom Index (FDI) and MOS 36-Item Short-Form Health Survey (SF-36) after treatment, 1 month and 3 months after treatment were observed and the clinical efficacy was assessed. After treatment, the total effective rate of abdominal fullness after meal, early satiation, upper abdominal pain and upper abdominal burning sensation were 84.8% (28/33), 67.7% (21/31), 76.9% (20/26) and 56.3% (9/16), respectively, in group A, and 45.9% (17/37), 38.7% (12/31), 42.9% (12/28) and 38.5% (5/13), respectively, in group B, and 15.8% (6/38), 18.4% (7/38), 46.1% (12/26) and 16.7% (4/24), respectively, in group C. The total effective rate of abdominal fullness after meal, early satiation and upper abdominal pain in group A were superior to those in group B (all P < 0.05), and the total effective rate of abdominal fullness after meal, early satiation, upper abdominal pain and upper abdominal burning sensation in group A were all superior to those in group C (all P < 0.05), and the total effective rate of abdominal fullness after meal in group B was superior to that in group C (P < 0.05). The score of FDI and SF-36 after treatment, 1 month and 3 months after treatment in all the groups were better than those before treatment (all P < 0.05), and above indices in group A were the most significant (all P < 0.05), and the scores of FDI and SF-36 after treatment in group B were better than those in group C (both P < 0.05). All the treatment of acupuncture at special acupoints, non-specific acupoints in Foot Yangming Meridian and non acupoints have therapeutic effect on FD, but acupuncture at special acupoints has better short and long term therapeutic effects, which confirm the existence of acupoints specificity.

Yue Z.H.,Hunan University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2012

To observe the differences of therapeutic effect of spastic paralysis after stroke between electroacupuncture and acupuncture and explore the mechanism. Sixty-four cases were randomly divided into an electroacupuncture group (n = 33) and an acupuncture group (n = 31). Both groups were treated with Bobath facilitation techniques and medicine treatments. Quchi (LI 11), Hegu (LI 4), Yanglingquan (GB 34), Sanyinjiao (SP 6), et al. on the affected side were selected in each group. The needle was retained for 30 min, and the manipulation was applied for 1 min in the acupuncture group, and electroacupuncture was added in the electroacupuncture group. Stroke Impairment Assessment Set (SIAS) was adopted to assess the whole function status after sroke, and the contents of glutamate (Glu) and gamma-aminobutyric acid (GABA) in serum and clinical efficacy were observed in the two groups. The SIAS score increased after treatment as compared with that before treatment in either group (both P < 0.01), and the electroacupuncture group was superior to the acupuncture group (P < 0.01); the content of Glu in blood serum and ratio of Glu/GABA reduced, while the content of GABA in serum increased after treatment as compared with those before treatment in either group (all P < 0.01), but the improvement of above indices were much more apparently in the electroacupuncture group as compared with those in the acupuncture group (P < 0.01, P < 0.05); the total effective rate of 90.9% (30/33) in the electroacupuncture group was superior to that of 83.9% (26/31) in the acupuncture group (P < 0.05). Electroacupuncture can improve therapeutic effect of spastic paralysis after stroke, it's mechanism may be ralated to ajusting the contents of Glu and GABA in serum.

Xie H.,Hunan University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2012

To observe the curative effect of different duration of mild moxibustion in superficial gastritis patients with deficiency cold pattern of spleen and stomach. A total of 84 superficial gastritis patients were randomly divided into moxibustion-20 min group, moxibustion-40 min group and medication (Ranitidine) group, with 28 cases in each group. Mild moxibustion was applied to bilateral Zusanli (ST 36) and Zhongwan (CV 12, odd days), Pishu (BL 20) and Weishu (BL 21, even-numbered days) for 20 min and 40 min respectively, once daily for 20 days. The symptom integrative score of superficial gastritis patients and the therapeutic effects were assessed according to "The Scoring Table for Symptoms and Signs of Gastrointestinal Disorders of Chinese Medicine", etc. Following 20 days' treatment, of the three 28 gastrititis patients in the medication, moxibustion-20 min and moxibustion-40 min groups, 0, 1, and 0 cases were cured, 5, 7 and 12 experienced marked improvement in their symptoms, 15, 16 and 12 had an improvement, and 8, 4 and 4 were invalid, with the effective rates being 71.4%, 85.7% and 85.7%, respectively. After one month's follow up, of the three 28 cases in the medication, moxibustion-20 min and moxibustion-40 min groups, 0, 4 and 0 cases were cured, 4, 8, and 13 experienced marked improvement, 15, 16 and 13 had an improvement, 9, 0 and 2 were ineffective, with the effective rates being 67.9%, 100% and 92.9%, respectively. Self-comparison of each group showed that the integrative scores of symptoms were all decreased significantly after the treatment and one-month's follow up in the three groups (P < 0.01). The effective rates of both moxibustion-20 min and -40 min were significantly higher than that of the medication group after one month's follow up (P < 0.01, P < 0.05). The therapeutic effect of moxibustion-20 min group was significantly superior to that of the medication group in lowering the integrative score of symptoms after one month's follow up (P < 0.01). No significant differences were found among the three groups in the therapeutic effects and in reducing integrative scores of symptoms after 20 days' treatment (P > 0.05). Mild moxibustion is significantly superior to medication in long-term therapeutic effects in the treatment of superficial gastritis patients with spleen-stomach deficiency-cold pattern.

He K.,Hunan University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2012

To verify the clinical efficacy on the function recovery of lower extremities for patients with cerebral apoplexy by the staging treatment with the combined therapy of the scalp and body acupuncture. Ninty-six cases were randomized into an observation group and a control group, 48 cases in each one. The conventional medication and rehabilitation therapy were given in each group. In the observation group, the combined therapy of the scalp acupuncture and the body acupuncture was provided by stages. At the flaccid stage, Futu (ST 32), Xuehai (SP 10), Zusanli (ST 36), etc. were selected. At the spasmodic stage, Huantiao (GB 30), Xuehai (SP 10), Yanglingquan (GB 34), etc. were selected. In combination with the scalp acupuncture the anterior oblique line of vertex-temploral (motor area) on the affected side was selected. In the control group, the acupoints were not selected according to the disease stages and no scalp acupuncture was applied, and the cases were treated with the needling technique as "regaining consciousness" and in light of the principle as "Yangming meridians specialized for Wei syndrome". The treatment lasted continuously for 8 weeks. The modified Fugl-Meyer motor function assessment (FMA) and Barthel index (BI) were used to assess the motor function of the lower extremities and the activities of daily living before and after treatment for the patients in two groups separately. FMA and BI score were all improved apparently after treatment for the patients in two groups (all P < 0.05), and FMA and BI score after treatment in the observation group were all higher than those in the control group (both P < 0.05). In 8 weeks treatment, the walking ability rate in the observation group was higher than that in the control group [56.3% (27/48) vs 35./4% (17/48), P < 0.05]. The walking speed in the observation group was faster than that in the control group (P < 0.05). The combined therapy of the scalp and body acupuncture in the staging treatment improves obviously the motor function of the lower extremities and the activities of daily living for the patients with cerebral apoplexy. This therapy recovers as quickly as possible the walking ability and speed for the patients, which is superior to the conventional acupuncture in comparison.

Guo S.,Hunan University | Yuan Y.,Memorial University of Newfoundland
Neural Networks | Year: 2011

In this paper, we construct a two-layer feedback neural network to theoretically investigate the influence of symmetry and time delays on patterned rhythmic behaviors. Firstly, linear stability of the model is investigated by analyzing the associated transcendental characteristic equation. Next, by means of the symmetric bifurcation theory of delay differential equations coupled with representation theory of standard dihedral groups, we not only investigate the effect of synaptic delays of signal transmission on the pattern formation, but also obtain some important results about the spontaneous bifurcation of multiple branches of periodic solutions and their spatio-temporal patterns. Thirdly, based on the normal form approach and the center manifold theory, we derive the formula to determine the bifurcation direction and stability of Hopf bifurcating periodic solutions. Finally, some numerical examples and the corresponding numerical simulations are used to illustrate the effectiveness of the obtained results. © 2010 Elsevier Ltd.

We design a long-tail shaped DNA probe for the label-free, isothermal and sensitive detection of nucleic acids based on cycled strand displacement amplification (Ltail-CSDA). The long-tail probe, a stem-loop structure with a long poly(T) tail at 5'-termini, integrates target-binding and amplification and signaling within one multifunctional design. The specific binding between the long-tail probe and the target triggers a polymerization reaction, during which a long dsDNA product is synthesized and the hybridized target is displaced by the strand displacement activity of polymerase. The displaced target forms another specific probe-target binding and prompts cycled polymerization reactions. The proposed Ltail-CSDA has the distinct advantages of its isothermal nature, free-label, simplicity and attomolar sensitivity compared with other existing technologies. More significantly, the dynamic range of the method is extremely large, covering nine orders of magnitude. Using total RNA samples extracted from hepatitis C virus (HCV) as targets, we further demonstrate the detection capability of the method for complex nucleic acid samples, indicating its potential applicability for clinic molecular diagnostic assays. Copyright © 2013 Elsevier B.V. All rights reserved.

Dregely D.,University of Stuttgart | Neubrech F.,University of Stuttgart | Neubrech F.,Kirchhoff Institute for Physics | Duan H.,Hunan University | And 2 more authors.
Nature Communications | Year: 2013

Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure. © 2013 Macmillan Publishers Limited. All rights reserved.

Zhang X.-B.,Hunan University | Zhang X.-B.,University of Illinois at Urbana - Champaign | Wang Z.,University of Illinois at Urbana - Champaign | Xing H.,University of Illinois at Urbana - Champaign | And 2 more authors.
Analytical Chemistry | Year: 2010

The catalytic beacon has emerged as a general platform for sensing metal ions and organic molecules. However, few reports have taken advantage of the true potential of catalytic beacons in signal amplification through multiple enzymatic turnovers, as existing designs require either equal concentrations of substrate and DNAzyme or an excess of DNAzyme in order to maintain efficient quenching, eliminating the excess of substrate necessary for multiple turnovers. On the basis of the large difference in the melting temperatures between the intramolecular molecular beacon stem and intermolecular products of identical sequences, we here report a general strategy of catalytic and molecular beacon (CAMB) that combines the advantages of the molecular beacon for highly efficient quenching with the catalytic beacon for amplified sensing through enzymatic turnovers. Such a CAMB design allows detection of metal ions such as Pb 2+ with a high sensitivity (LOD = 600 pM). Furthermore, the aptamer sequence has been introduced into DNAzyme to use the modified CAMB for amplified sensing of adenosine with similar high sensitivity. These results together demonstrate that CAMB provides a general platform for amplified detection of a wide range of targets. © 2010 American Chemical Society.

Yuan Z.,Hunan University | Zou X.,University of Western Ontario
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, a general mathematical model is proposed with detailed justifications to describe the spread of a disease with latency in a heterogeneous host population which includes many existing ones as special cases. For a simpler version that assumes an identical natural death rate for all groups, and with a gamma distribution for the latency, the model is shown to demonstrate the global threshold dynamics in terms of the basic reproduction number R0 of the model: if R0≤1, the disease-free equilibrium is globally asymptotically stable in the positive orthant, whereas if R0>1, a unique endemic equilibrium exists and is globally asymptotically stable in the interior of the positive orthant. The proofs of the main results make use of the theory of non-negative matrices, persistence theory in dynamical systems, Lyapunov functions and a subtle grouping technique in estimating the derivatives of Lyapunov functions guided by graph theory, which was recently developed and applied by several authors to some relateted epidemic models. © 2009 Elsevier Ltd. All rights reserved.

Nie Z.,Hunan University | Wang P.,Purdue University | Tian C.,Purdue University | Mao C.,Purdue University
Angewandte Chemie - International Edition | Year: 2014

Herein, we report a strategy for the synchronization of two self-assembly processes to assemble stimulus-responsive DNA nanostructures under isothermal conditions. We hypothesized that two independent assembly processes, when brought into proximity in space, could be synchronized and would exhibit positive synergy. To demonstrate this strategy, we assembled a ladderlike DNA nanostructure and a ringlike DNA nanostructure through two hybridization chain reactions (HCRs) and an HCR in combination with T-junction cohesion, respectively. Such proximity-induced synchronization adds a new element to the tool box of DNA nanotechnology. We believe that it will be a useful approach for the assembly of complex and responsive nanostructures. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Xiao C.,Oakland University | Xiao C.,Hunan University | Rehman A.,Oakland University | Zeng X.,Oakland University
Analytical Chemistry | Year: 2012

Motivated by the use of ionic liquids (ILs) as green replacers of traditional electrolytes, a mechanistic study has been systematically conducted to comprehend various design principles responsible for electrochemical profiling of redox-active species in ILs. The full spectrum of properties associated with ILs is exploited to assess the viability of this platform, thus revealing the correlation between the redox properties and the physiochemical parameters of the species involved. This includes the evaluation of (1) the variation of redox responses toward analytes with similar molecular structures or functionalities of ILs, (2) the influence in terms of physical criteria of the system such as viscosity and conductivity as well as chemical structure of ILs, and (3) the sustainability in harsh conditions (high temperature or humidity) and interferences. The principle is exemplified via trinitrotoluene (TNT) and dinitrotoluene (DNT) with inherent redox activity as analytes and IL membranes as solvents and electrolytes using glassy carbon (GC) electrodes. A discrete response pattern is generated that is analyzed through linear discriminant analysis (LDA) leading to 100% classification accuracy even for the mixture of analytes. Quantitative analysis through square wave voltammetry (SWV) gave rise to the detection limits in liquid phase of 190 and 230 nM for TNT and DNT, respectively, with a linear range up to 100 μM. Gas-phase analysis shows strong redox signals for the estimated concentrations of 0.27 and 2.05 ppm in the gas phase for TNT and DNT, respectively, highlighting that ILs adopt a role as a preconcentrator to add on sensitivity with enhanced selectivity coming from their physiochemical diversity, thus addressing the major concerns usually referred to most sensor systems. © 2011 American Chemical Society.

Zhang D.,Central South University | Zhang D.,Hunan University | Dai B.,Central South University
Computers and Mathematics with Applications | Year: 2011

In this paper, we consider the existence of solutions for a class of nonlinear impulsive problems with periodic boundary conditions. By using critical point theory, we obtain some existence theorems of infinitely many solutions for the nonlinear impulsive problem when the impulsive functions are superlinear. We extend and improve some recent results. © 2011 Elsevier Ltd. All rights reserved.

Zhang W.,Hunan University
International Journal of Digital Content Technology and its Applications | Year: 2012

For tasks of 3D environment modeling and target identification in mobile robot navigation, this paper proposed a method based on 3D camera to model in 3D spatial environment and identify target in environment, which consists of two parts: spatial modeling and target identification. As linear features obtained from original image in real-time have the problem of ambiguity, in order to solve this problem, firstly we use 3D straight lines to find out real surfaces, and then identify environmental objectives. The main methods used in this paper including Principle Component Analysis (PCA) and Iterative Closest Point (ICP). Experiments were conducted in real indoor corridor environment, and the experimental results verified that the proposed method can effectively identify targets like entrance, doors and elevators.

Zhong M.,Hunan University
Advanced Materials Research | Year: 2012

Stone buildings have long history in west Hunan, stone is one of the most important building material that has been widely used in traditional building, village and town constructions especially in rural mountainous minority areas where rock resource is abundant. Stone is natural and compatible with the environment. Buildings built with local natural stone material in west Hunan minority areas are worth studying considering sustainable development and culture protection. Stone slab masonry in the south with grey limestone slabs and rubble masonry in the north with brown rubbles are two different types. Stone dominates the exterior, while the interior and main structures are built of wood like most of the traditional Chinese buildings. Traditional building techniques are passed on in the stone buildings while they also form the unique culture image of west Hunan rural areas. © (2012) Trans Tech Publications, Switzerland.

Sun Z.,Hunan University | Zeng J.,Dongguan University of Technology
Optimization Methods and Software | Year: 2011

The mixed linear complementarity problem is reformulated as a non-smooth equation by the use of the median operator. On the basis of slant differentiability, a damped semismooth Newton method for solving the non-smooth equation is presented. Both monotone and finite termination properties of the proposed method are proved. © 2011 Taylor & Francis.

Liu Z.,Texas A&M University | Deng H.,Hunan University | Mukherjee P.P.,Texas A&M University
ACS Applied Materials and Interfaces | Year: 2015

Li intercalation and diffusion in pristine and modified SnS2 interlayer are studied by a first-principles approach. The results predict that the octahedral interstitial site is energetically favored for Li intercalation. The minimum energy path of Li diffusion in SnS2 interlayer is investigated by climbing image nudged elastic band method. It is found that Li atom diffuses from one energetically favored octahedral interstitial site to the neighbor one via tetrahedral interstitial site. The expansion of interlayer spacing is beneficial for decreasing the diffusion barrier. Ce dopant negatively impacts the Li diffusivity although it can optimize the interlayer spacing. Geometric structures of LixSnS2 (0 < x ≥ 3) are investigated to understand the lithiation-induced volume expansion and atomic structure change. The lithiation process can be divided into two stages. When Li content (x in LixSnS2) is less than 1, the volume expansion is not dramatic and only S atoms capture electrons from Li atoms. When Li content is larger than 1, Sn4+ cations are significantly reduced, S-Sn-S trilayer gradually decomposes, and LixS2 (1 ≥ x ≥ 3) layer forms between two Sn monolayers. The mechanism of volume expansion is elucidated in this study. © 2015 American Chemical Society.

Zhao X.-H.,Henan University of Traditional Chinese Medicine | Zhao X.-H.,Hunan University | Ma Q.-J.,Henan University of Traditional Chinese Medicine | Wu X.-X.,Henan University of Traditional Chinese Medicine | Zhu X.,Henan University of Traditional Chinese Medicine
Analytica Chimica Acta | Year: 2012

Based on the super fluorescence quenching efficiency of graphene oxide and exonuclease III aided signal amplification, we develop a facile, sensitive, rapid and cost-effective method for DNA detection. In the presence of target DNA, the target-probe hybridization forms a double-stranded structure and exonuclease III catalyzes the stepwise removal of mononucleotides from the blunt 3' termini of probe, resulting in the recycling of the target DNA and signal amplification. Therefore, our proposed sensor exhibits a high sensitivity towards target DNA with a detection limit of 20. pM, which was even lower than previously reported GO-based DNA sensors without enzymatic amplification, and provides a universal sensing platform for sensitive detection of DNA. © 2012 Elsevier B.V.

Herein, we demonstrated a new optical microscopy method to selectively image small-size gold nanoparticles (GNPs) inside noisy living cells through determination of the difference image between the probe beam (illuminated at the resonance wavelength of GNPs, 532 nm) and the reference beam (illuminated at 473 nm). From computer simulation and single-particle imaging experiments, we demonstrated that GNPs with a diameter of 45 nm could be selectively imaged in the GNPs/cell lysates mixture and inside living cells by dual-wavelength difference (DWD) imaging. The diffusion dynamics of nucleic acids functionalized GNPs on cell membranes and the internalization kinetics of these GNPs by living cells were explored with this method. Our real-time tracking experiments showed that statistically 80% of GNPs were under restricted diffusion on the cell membrane. The cell cytoskeleton fence effect, as observed in the single-particle tracking experiments, may be one of the main factors for the restricted diffusion mode.

Wu D.,Hunan University
Journal of Networks | Year: 2013

Cloud computing is attracting more and more researchers and enterprises, because it can deal with massive data with cheap commodity computers. Medical data are very important for disease analysis in order to better serve the patients, but the privacy of patients must be handled first. In this paper, we apply the cloud platform to build a medical data center for data mining, and propose an improved k-anonymity algorithm for medical data in such setting. The experiments show that our proposed algorithm is more efficient than the original k-anonymity algorithm, and can be used in medical data analysis in many data mining algorithms while not increasing the overall overhead a lot. © 2013 ACADEMY PUBLISHER.

Li F.,Hunan University | Li F.,Zte United States Inc. | Li X.,Fudan University | Yu J.,Fudan University
Journal of Lightwave Technology | Year: 2015

In this paper, we experimentally compared the performance of discrete-Fourier-transform spread (DFT-spread) and pre-equalization in a 244.2-Gb/s polarization-division-multiplexed 16-ary quadrature amplitude-modulation orthogonal frequency-division multiplexing (PDM-16QAM-OFDM) transmission system. The pre-equalization is effective to overcome the high-frequency power attenuation in the channel. However, the acquisition of static channel response for pre-equalization is really complicated and the peak-to-average power ratio (PAPR) of the signal after pre-equalization even becomes a little higher. The DFT-spread can be applied to simultaneously resist high-frequency power attenuation and reduce the PAPR of OFDM signal. The experimental results also show that one band DFT-spread demonstrates the best narrow optical filtering tolerance. The transmission distance for 8 × 244.2-Gb/s wavelength-division-multiplexing (WDM) PDM-16QAM-OFDM at the soft-decision forward-error correction threshold of 2.4 × 10-2 is 2 × 420 km based on pre-equalization, while extended to over 3 × 420 km based on one band DFT-spread, which well illustrates one band DFT-spread is more efficient for high-bandwidth coherent WDM-OFDM system. © 2014 IEEE.

Yang K.,Changsha Medical University | Yang K.,Hunan University | Zeng M.,Changsha Medical University
New Journal of Chemistry | Year: 2013

A novel multiresponsive hydrogel based on polyacrylamide functionalized with thymine derivatives has been demonstrated. In this study, thymines are grafted to the polyacrylamide chains by introducing thymines to the acrylamide precursors. Based on the photodimerization/cleavage of grafted thymines, the reversible sol-gel transition can be operated by alternate irradiation with 365 and 240 nm UV light. More importantly, thymine-functionalized polyacrylamide can combine with each other by the formation of a thymine(T)-Hg2+- thymine(T) complex to form a hydrogel in the presence of Hg2+. The formed hydrogel can gradually dissolve with the dissociation of the T-Hg 2+-T complex by a series of external stimuli such as pH, thymine and thiol compounds. Subsequently, Ru(bipy)3 2+ dye-doped silica nanoparticles (FSiNPs) are selected as model guests and loaded into hydrogel to demonstrate multiresponsive controlled release behavior. Moreover, the FSiNPs loaded with Hg2+-cross-linked hydrogel can be employed as a sensor for the detection of cysteine biomolecule. These results indicate that thymine-functionalized polyacrylamide can not only realize a multiresponsive gel-sol transition but also has a promising application in the field of controlled release and biochemical analysis. © 2013 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Manfrinato V.R.,Massachusetts Institute of Technology | Zhang L.,Brookhaven National Laboratory | Su D.,Brookhaven National Laboratory | Duan H.,Hunan University | And 3 more authors.
Nano Letters | Year: 2013

We investigated electron-beam lithography with an aberration-corrected scanning transmission electron microscope. We achieved 2 nm isolated feature size and 5 nm half-pitch in hydrogen silsesquioxane resist. We also analyzed the resolution limits of this technique by measuring the point-spread function at 200 keV. Furthermore, we measured the energy loss in the resist using electron-energy-loss spectroscopy. © 2013 American Chemical Society.

Cai Y.,Central South University of forestry and Technology | Fan C.-L.,Hunan University
Electrochimica Acta | Year: 2011

Mesocarbon microbeads (MCMB) and needle coke (NC) with different shapes were selected to investigate the influences of conductive additives acetylene black (AB) and polyaniline (PAn). Experiments showed that the granularity distribution of spherical MCMB is narrow and does not contain small particles. Its electronic conductivity is lower than that of NC. Therefore, compared to NC, MCMB anode possesses a lower discharge capacity although their structural parameters are similar to each other. The addition of AB and PAn can improve the electrochemical performances of MCMB anode by enhancing the electronic conductivity of anode films. Owing to the fact PAn possessing a high electronic conductivity of 15.29 S cm-1, it plays a better role than AB. The discharge capacity of MCMB anode using 5 wt.% PAn reaches the maximum value of 341.1 mAh g-1. Excessive addition of PAn will hinder the dispersing of lithium ions and decrease the discharge capacity. The content of PAn and AB in MCMB anode conforms to the percolation theory. MCMB anode containing 5 wt.% PAn possesses the excellent cycle performance and small change of charge transfer resistance in the 30th cycle. © 2011 Elsevier Ltd. All rights reserved.

Zou S.,Hunan University | Wu J.,York University | Chen Y.,Wilfrid Laurier University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

We consider a delayed susceptible-infected-recovered epidemic model on an uncorrelated complex network and address the effect of time lag on the shape and multiple waves of epidemic curves. We show that when the transmission rate is above a threshold, a large delay can cause multiple waves with larger amplitudes in the second and subsequent waves. © 2011 American Physical Society.

Lei Y.,Hunan University | Adhikari S.,University of Swansea | Friswell M.I.,University of Swansea
International Journal of Engineering Science | Year: 2013

This paper investigates the dynamic behavior of nonlocal viscoelastic damped nanobeams. The Kelvin-Voigt viscoelastic model, velocity-dependent external damping and Timoshenko beam theory are employed to establish the governing equations and boundary conditions for the bending vibration of nanotubes. Using transfer function methods (TFM), the natural frequencies and frequency response functions (FRF) are computed for beams with different boundary conditions. Unlike local structures, taking into account rotary inertia and shear deformation, the nonlocal beam has maximum frequencies, called the escape frequencies or asymptotic frequencies, which are obtained for undamped and damped nonlocal Timoshenko beams. Damped nonlocal beams are also shown to possess an asymptotic critical damping factor. Taking a carbon nanotube as a numerical example, the effects of the nonlocal parameter, viscoelastic material constants, the external damping ratio, and the beam length-to-diameter ratio on the natural frequencies and the FRF are investigated. The results demonstrate the efficiency of the proposed modeling and analysis methods for the free vibration and frequency response analysis of nonlocal viscoelastic damped Timoshenko beams. © 2013 Elsevier Ltd.

Deng X.,Hunan University | Deng X.,Yangtze University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2013

In this paper, according to the idea of the weight of a polynomial introduced by Swinnerton-Dyer(Math Proc Camb Philos Soc 132:385-393, 2002), we successfully find all the invariant algebraic surfaces of the generalized Lorenz system x′ = a(y - x), y′ = bx + cy - xz, z′ = xy + dz. © 2012 Springer Basel.

Liu Q.,Hunan University
Soils and Foundations | Year: 2016

Seismic response of flexible cantilever wall retaining a semi-infinite viscoelastic soil under plane strain condition is investigated in this study. A novel modal analysis is derived based on the assumption of vanishing vertical displacements of the soil-wall system. The horizontal displacements of the soil-wall system are expressed by a series of modes in terms of the separate variable method. The boundary value problem is solved by considering the soil-wall interaction. Good agreement of the proposed solution results with those by the available methods confirms its accuracy. Closed-form solutions are derived for the following: (i) the displacement and stress field of the soil-wall system; (ii) the stiffness in the mth mode and dynamic Winkler modulus of the soil; (iii) translational and rotational response factors of the wall; (iv) the displacement amplification factor at the wall top. Kinematic response of the soil-wall system is evaluated in order to assess dynamic behavior of the wall. © 2016 Japanese Geotechnical Society.

Wenzhen Z.,Hunan University
International Journal of Advancements in Computing Technology | Year: 2012

This paper proposes an improved Valley-Fill (VF) ballast circuit with current fed resonant inverter driving circuit of for a high power factor VF electronic ballasts. The original VF circuit allows the input current 150 ° to 30 ° transmission, and then from 210 ° to 330 °. Because the continuity and high tensile strength of the total harmonic distortion () results input currents. Fixed VF circuit allows the Angle of conduction further extensions line current 0 ° and 180 ° more than more than 168.86 ° omega t more than 333 ° omega is more than t. This VF circuit also reduces the current spike, compared to conventional VF ballast.

Liu Q.H.,Hunan University
Journal of Mathematical Physics | Year: 2013

The canonical quantization is a procedure for quantizing a classical theory while preserving the formal algebraic structure among observables in the classical theory to the extent possible. For a system without constraint, we have the so-called fundamental commutation relations (CRs) among positions and momenta, whose algebraic relations are the same as those given by the Poisson brackets in classical mechanics. For the constrained motion on a curved hypersurface, we need more fundamental CRs otherwise neither momentum nor kinetic energy can be properly quantized, and we propose an enlarged canonical quantization scheme with introduction of the second category of fundamental CRs between Hamiltonian and positions, and those between Hamiltonian and momenta, whereas the original ones are categorized into the first. As an N - 1 (N ≥ 2) dimensional hypersurface is embedded in an N dimensional Euclidean space, we obtain the proper momentum that depends on the mean curvature. For the spherical surface, a long-standing problem in the form of the geometric potential is resolved in a lucid and unambiguous manner, which turns out to be identical to that given by the so-called confining potential technique. In addition, a new dynamical group SO(N, 1) symmetry for the motion on the sphere is demonstrated. © 2013 AIP Publishing LLC.

Liu W.,Hunan University | Mu W.,Georgia Institute of Technology | Liu M.,Georgia Institute of Technology | Zhang X.,Georgia Institute of Technology | And 2 more authors.
Nature communications | Year: 2014

The current polymer-exchange membrane fuel cell technology cannot directly use biomass as fuel. Here we present a solar-induced hybrid fuel cell that is directly powered with natural polymeric biomasses, such as starch, cellulose, lignin, and even switchgrass and wood powders. The fuel cell uses polyoxometalates as the photocatalyst and charge carrier to generate electricity at low temperature. This solar-induced hybrid fuel cell combines some features of solar cells, fuel cells and redox flow batteries. The power density of the solar-induced hybrid fuel cell powered by cellulose reaches 0.72 mW cm(-2), which is almost 100 times higher than cellulose-based microbial fuel cells and is close to that of the best microbial fuel cells reported in literature. Unlike most cell technologies that are sensitive to impurities, the cell reported in this study is inert to most organic and inorganic contaminants present in the fuels.

Huang H.-J.,Jiangxi Agricultural University | Yuan X.-Z.,Hunan University
Bioresource Technology | Year: 2016

Various hydrothermal treatment methods, including hydrothermal carbonization, liquefaction and sub/super-critical water gasification, have been applied to the disposal of sewage sludge for producing bio-materials or bio-fuels. It has become a research hotspot whether the heavy metals contained in sewage sludge can be well treated/stabilized after the hydrothermal treatments. This review firstly summarized the methods of assessing heavy metals' contamination level/risk and then discussed the migration and transformation behaviors of heavy metals from the following aspects: the effect of reaction temperature, the effect of additives (catalysts and other biomass), the effect of the type of solvent and the effect of reaction time. This review can provide an important reference for the further study of the migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge. © 2015 Elsevier Ltd.

Wang S.,Hunan University
Journal of Combinatorial Theory. Series B | Year: 2015

Let P be a locally finite poset with the interval space Int(P), and R be a ring with identity. We shall introduce the Möbius conjugation μ* sending each function f:P→R to an incidence function μ*(f):Int(P)→R such that μ*(fg)=μ*(f)*μ*(g). Taking P to be the intersection poset of a hyperplane arrangement A, we shall obtain a convolution identity for the number r(A) of regions and the number b(A) of relatively bounded regions, and a reciprocity theorem of the characteristic polynomial χ(A,t) which gives a combinatorial interpretation of the values |χ(A,-q)| for large primes q. Moreover, all known convolution identities on Tutte polynomials of matroids will be direct consequences after specializing the poset P and functions f,g. © 2015 Elsevier Inc.

Zhang Z.,Hunan University | Hou Z.,University of South China
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, we investigate a non-autonomous ratio-dependent predator-prey model with exploited terms. By means of using coincidence degree theory, we establish the existence of at least four positive periodic solutions for the above model. © 2009 Elsevier Ltd. All rights reserved.

Guo S.,Hunan University
Nonlinear Dynamics | Year: 2010

This paper addresses the computation of equivariant normal forms for some Neutral Functional Differential Equations (NFDEs) near equilibria in the presence of symmetry. The analysis is based on the theory previously developed for autonomous retarded Functional Differential Equations (FDEs) and on the existence of center (or other invariant) manifolds. We illustrate our general results by some applications to a detailed case study of additive neurons with delayed feedback. © 2010 Springer Science+Business Media B.V.

Luo J.,Xiamen University of Technology | Luo J.,University of Ottawa | Yu D.,Hunan University | Liang M.,University of Ottawa
Measurement Science and Technology | Year: 2013

This paper presents an adaptive demodulation technique for bearing fault detection. It is implemented via the tunable-Q wavelet transform (TQWT). With the TQWT, the bearing vibration signal is decomposed into sub-signals corresponding to different band-pass filters of the TQWT. Kurtosis as an effective indicator of signal impulsiveness is adopted to guide the merging of the sub-signals leading to a signal component which contains information most relevant to the bearing fault. The purpose of the proposed approach is to adaptively search for the best filter for envelope demodulation analysis. In fact, the implementation of the proposed method can be interpreted as the process to obtain the optimal filter for the Hilbert demodulation analysis by two steps of merging of the band-pass filters of the TQWT. The effectiveness of the proposed method has been demonstrated by both simulation and experimental analyses. © 2013 IOP Publishing Ltd.

Dong P.,Hunan University
Advances in Structural Engineering | Year: 2011

Standards for seismic design of building structures have been applied in China since 1978 However, the Chinese seismic design philosophy is quite different from the capacity design philosophy incorporated in New Zealand's Standards. In this paper, the disadvantages of Chinese Standards designed RC frame structures (potential structural flexural and shear collapses when subjected to "large earthquakes" at ultimate limit state level) are discussed when compared to New Zealand Standards designed frame structures. To suppress the potential flexural collapse, a cycling research project is presented, comprising of member experimental tests for hysteresis loops (further for hysteresis models), inelastic dynamic time-history analyses for seismic damage assessment purposes (taking overall structural displacement ductility as principle damage measurement), redesign of members if flexural collapse is predicted, experimental tests again of redesigned members etc. Meanwhile, having the potential shear collapse suppressed, the capacity design procedure needs to be applied to seismic design, leading to quantify the structural displacement ductility capacities.

Yuan Z.,Hunan University | Zou X.,University of Western Ontario
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, we consider a reaction diffusion model for competing pioneer and climax species. A previous work has established the existence of traveling wave fronts connecting two competition-exclusion equilibria in certain range of the parameters, while in this paper, we explore the possibility of traveling wave fronts connecting the pioneer-invasion-only equilibrium and the co-invasion equilibrium. By combining the Schauder's fixed point theorem with a pair of the so called desired functions, we show that the model does support such co-invasion waves in some other ranges of parameters. We also determine the minimal speed for such co-invasion waves in terms of the parameters, and discuss some biological implications and significance of the results. © 2008 Elsevier Ltd.

Xu Y.,Hunan University | Qu R.,University of Nottingham
Computer Communications | Year: 2012

This paper presents the first fitness landscape analysis on the delay-constrained least-cost multicast routing problem (DCLC-MRP). Although the problem has attracted an increasing research attention over the past decade in telecommunications and operational research, little research has been conducted to analyze the features of its underlying landscape. Two of the most commonly used landscape analysis techniques, the fitness distance correlation analysis and the autocorrelation analysis, have been applied to analyze the global and local landscape features of DCLC-MRPs. A large amount of simulation experiments on a set of problem instances generated based on the benchmark Steiner tree problems in the OR-library reveals that the landscape of the DCLC-MRP is highly instance dependent with different landscape features. Different delay bounds also affect the distribution of solutions in the search space. The autocorrelation analysis on the benchmark instances of different sizes and delay bounds shows the impact of different local search heuristics and neighborhood structures on the fitness distance landscapes of the DCLC-MRP. The delay bound constraint in the DCLC-MRP has shown a great influence on the underlying landscape characteristic of the problem. Based on the fitness landscape analysis, an iterative local search (ILS) approach is proposed in this paper for the first time to tackle the DCLC-MRP. Computational results demonstrate the effectiveness of the proposed ILS algorithm for the problem in comparison with other algorithms in the literature. © 2011 Elsevier B.V. All rights reserved.

Zou Y.,Iowa State University | Zou Y.,Hunan University | Tassin P.,Iowa State University | Koschny T.,Iowa State University | And 2 more authors.
Optics Express | Year: 2012

We have recently shown that graphene is unsuitable to replace metals in the current-carrying elements of metamaterials. At the other hand, experiments have demonstrated that a layer of graphene can modify the optical response of a metal-based metamaterial. Here we study this electromagnetic interaction between metamaterials and graphene. We show that the weak optical response of graphene can be modified dramatically by coupling to the strong resonant fields in metallic structures. A crucial element determining the interaction strength is the orientation of the resonant fields. If the resonant electric field is predominantly parallel to the graphene sheet (e.g., in a complementary split-ring metamaterial), the metamaterial's resonance can be strongly damped. If the resonant field is predominantly perpendicular to the graphene sheet (e.g., in a wire-pair metamaterial), no significant interaction exists. © 2012 Optical Society of America.

Yi T.,Hunan University | Zou X.,University of Western Ontario
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2010

In this paper, we consider a class of delay reaction-diffusion equations (DRDEs) with a parameter ε > 0. A homogeneous Neumann boundary condition and non-negative initial functions are posed to the equation. By letting ε → 0, such an equation is formally reduced to a scalar difference equation (or map dynamical system). The main concern is the relation of the absolute (or delay-independent) global stability of a steady state of the equation and the dynamics of the nonlinear map in the equation. By employing the idea of attracting intervals for solution semiflows of the DRDEs, we prove that the globally stable dynamics of the map indeed ensures the delay-independent global stability of a constant steady state of the DRDEs. We also give a counterexample to show that the delayindependent global stability of DRDEs cannot guarantee the globally stable dynamics of the map. Finally, we apply the abstract results to the diffusive delay Nicholson blowfly equation and the diffusive Mackey-Glass haematopoiesis equation. The resulting criteria for both model equations are amazingly simple and are optimal in some sense (although there is no existing result to compare with for the latter). © 2010 The Royal Society.

Liu K.,University of Sheffield | Zhu Z.Q.,University of Sheffield | Zhang Q.,Huazhong University of Science and Technology | Zhang J.,Hunan University
IEEE Transactions on Industrial Electronics | Year: 2012

This paper investigates the influence of nonideal voltage measurements on the parameter estimation of permanentmagnet synchronous machines (PMSMs). The influence of nonideal voltage measurements, such as the dc bus voltage drop, zero shift in the amplifier, and voltage source inverter nonlinearities, on the estimation of different machine parameters is investigated by theoretical and experimental analysis. For analysis, a model-reference-adaptive-system-based estimator is first described for the parameter estimation of the q-axis inductance, stator winding resistance, and rotor flux linkage. The estimator is then applied to a prototype surface-mounted PMSM to investigate the influence of nonideal voltage measurement on the estimation of various machine parameter values. It shows that, at low speed, the inverter nonlinearity compensation has significant influence on both the rotor flux linkage and winding resistance estimations while, at high speed, it has significant influence only on the winding resistance estimation and has negligible influence on the rotor flux linkage estimation. In addition, the inverter nonlinearity compensation will not influence the q-axis inductance estimation when it is under id = 0 control. However, the dc bus voltage drop due to the load variation and zero shift in the amplifier will significantly influence the q-axis inductance estimation. © 2011 IEEE.

Song H.,Hunan University | Song H.,Hong Kong Baptist University
International Journal of Computer Mathematics | Year: 2015

We present the numerical methods for the Cahn–Hilliard equation, which describes phase separation phenomenon. The goal of this paper is to construct high-order, energy stable and large time-stepping methods by using Eyre's convex splitting technique. The equation is discretized by using a fourth-order compact difference scheme in space and first-order, second-order or third-order implicit–explicit Runge–Kutta schemes in time. The energy stability for the first-order scheme is proved. Numerical experiments are given to demonstrate the performance of the proposed methods. © 2014 Taylor & Francis.

Xu Y.,University of Nottingham | Xu Y.,Hunan University | Qu R.,University of Nottingham
Applied Intelligence | Year: 2012

This paper investigates the first hybrid scatter search and path relinking meta-heuristic for the Delay-Constrained Least-Cost (DCLC) multicast routing problem. The underpinning mathematic model of the DCLC multicast routing problem is the constrained Steiner tree problem in graphs, a well known NP-complete problem. After combining a path relinking method as the solution combination method in scatter search, we further explore two improvement strategies: tabu search and variable neighborhood search, to intensify the search in the hybrid scatter search algorithm. A large number of simulations on some benchmark instances from the OR-library and a group of random graphs of different characteristics demonstrate that the improvement strategy greatly affects the performance of the proposed scatter search algorithm. The hybrid scatter search algorithm intensified by a variable neighborhood descent search is highly efficient in solving the DCLC multicast routing problem in comparison with other algorithms and heuristics in the literature. © 2010 Springer Science+Business Media, LLC.

Huang K.-J.,Xinyang Normal University | Huang K.-J.,Hunan University | Liu Y.-J.,Xinyang Normal University | Liu Y.-M.,Xinyang Normal University | Wang L.-L.,Xinyang Normal University
Journal of Hazardous Materials | Year: 2014

Two-dimensional transition metal dichalcogenide are attracting increasing attention in electrochemical sensing due to their unique electronic properties. In this work, flower-like molybdenum disulfide (MoS2) was prepared by a simple hydrothermal method. The scanning electron microscopy and transmission electron microscopy images showed the MoS2 nanoflower had sizes with diameter of about 200nm and was constructed with many irregular sheets as a petal-like structure with thickness of several nanometers. A novel electrochemical sensor was constructed for the determination of bisphenol A (BPA) based on MoS2 and chitosan-gold nanoparticles composites modified electrode. The sensor showed an efficient electrocatalytic role for the oxidation of BPA, and the oxidation overpotentials of BPA decreased significantly and the peak current increased greatly compared with bare GCE and other modified electrode. A good linear relationship between the oxidation peak current and BPA concentration was obtained in the range from 0.05 to 100μM with a detection limit of 5.0×10-9M (S/N=3). The developed sensor exhibited high sensitivity and long-term stability, and it was successfully applied for the determination of BPA in different samples. This work indicated MoS2 nanoflowers were promising in electrochemical sensing and catalytic applications. © 2014 Elsevier B.V.

The development of autonomous DNA machines and their use for specific sensing purpose have recently attracted considerable research attention. In existing autonomous machines, the target recognition process and signal transduction are separated from each other. This results in misunderstanding of the operation behavior, and the assay capability is compromised when serving as a sensing tool. In this communication, the integrated signal transduction-based autonomous aptameric machine, in which the recognition element and signal reporters are integrated into a DNA strand, is developed. This new machine can execute the in situ amplification of target binding-induced signal. The authentic operation behavior of autonomous DNA machine is discovered: the machine's products directly hybridize to the "track" rather than to the signaling probes. Along this line, the machine is employed to detect the cocaine in a more straightforward fashion, and improved assay characteristics (for example, the dynamic response range is widened by more than 500-fold) are achieved. Our efforts not only clarify the concept described in traditional autonomous DNA machines but also have made technological advancements that are expected to be especially valuable in designing nucleic acid-based machines employed in basic research and medical diagnosis. Copyright © 2013 Elsevier B.V. All rights reserved.

We present here a highly selective and sensitive label-free method to detect Hg(2+) ions in aqueous solution by using DNA molecular machine-based fluorescent Ag nanoclusters (AgNCs). This mechanism is based on the Hg(2+) ions triggering machine-like operations of DNA and the "product" of the machine being used to stabilize fluorescent AgNCs. In this method, a tailored DNA, containing a sequence for Hg(2+) ions recognition, a sequence-specific nicking site for Nb BbvC I and a sequence complementary to the DNA as a template for the synthesis of fluorescent AgNCs, was firstly designed. In the presence of Hg(2+) ions, the machine's function operations were triggered. A series of machine-like operations, including replication, scission, and displacement then occurred with the addition of polymerase/dNTPs/Nb BbvC I, which manufactured lots of "product" DNA. The "product" DNA could act as a template for the preparation of fluorescent AgNCs. Thus the fluorescence of the AgNCs could be used as a signal transduction of this DNA machine, which was related to the concentration of the Hg(2+) ions. The repeated synthesis of the "product" and its template effect for AgNCs synthesis led to signal amplification in the assay of Hg(2+) ions. A linear response to the concentration of Hg(2+) ions was observed in the range from 0.08 nM to 20 nM and a detection limit of 0.08 nM was obtained. By contrast, the operation of the machine could not be executed in an Hg(2+) ion-free system. Moreover, the detection was not only label-free but also specific for Hg(2+) ions without being affected by other metal ions.

Fan J.C.,KTH Royal Institute of Technology | Fan J.C.,Anhui University of Technology | Sreekanth K.M.,KTH Royal Institute of Technology | Sreekanth K.M.,Amrita University | And 3 more authors.
Progress in Materials Science | Year: 2013

In the past 10 years, ZnO as a semiconductor has attracted considerable attention due to its unique properties, such as high electron mobility, wide and direct band gap and large exciton binding energy. ZnO has been considered a promising material for optoelectronic device applications, and the fabrications of high quality p-type ZnO and p-n junction are the key steps to realize these applications. However, the reliable p-type doping of the material remains a major challenge because of the self-compensation from native donor defects (VO and Zni) and/or hydrogen incorporation. Considerable efforts have been made to obtain p-type ZnO by doping different elements with various techniques. Remarkable progresses have been achieved, both theoretically and experimentally. In this paper, we discuss p-type ZnO materials: theory, growth, properties and devices, comprehensively. We first discuss the native defects in ZnO. Among the native defects in ZnO, VZn and O i act as acceptors. We then present the theory of p-type doping in ZnO, and summarize the growth techniques for p-type ZnO and the properties of p-type ZnO materials. Theoretically, the principles of selection of p-type dopant, codoping method and XZn-2VZn acceptor model are introduced. Experimentally, besides the intrinsic p-type ZnO grown at O-rich ambient, p-type ZnO (MgZnO) materials have been prepared by various techniques using Group-I, IV and V elements. We pay a special attention to the band gap of p-type ZnO by band-gap engineering and room temperature ferromagnetism observed in p-type ZnO. Finally, we summarize the devices based on p-type ZnO materials. © 2013 Elsevier Ltd. All rights reserved.

A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

Yang L.,Hunan University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2013

To explore the rule of influence of chitosan flocculation clarification and alcohol precipitation on the chemical compositions in aqueous extract of Paeoniae Radix Alba. The fingerprints of aqueous extracts of Radix Paeoniae Alba were established by HPLC method, and the influences of the two purification methods on the chemical compositions in aqueous extract of Paeoniae Radix Alba were compared with the apparent content and relative apparent content of the composition as evaluation indexes. The chitosan flocculation clarification was superior to alcohol precipitation for keeping the polar compositions in aqueous extract, close to alcohol precipitation for keeping the medium polar compositions, and inferior to alcohol precipitation for keeping the lower polar compositions. The experiment result provides evidence for reasonably selecting above two purification methods to purify aqueous extract of Chinese medicinal herbs.

Duan X.,Nankai University | Ma J.,Hunan University | Lian J.,Chinese University of Hong Kong | Zheng W.,Nankai University
CrystEngComm | Year: 2014

Wet chemistry using ionic liquids as the medium has proven to be highly efficient for the preparation of several types of metallic, metal oxides, and other kinds of semiconductor nanostructures, and so on. This article reviews state-of-the-art research activities in the field, focusing on the use of ionic liquids as a versatile regent for the synthesis of various nanoparticle systems. We begin with a survey of choices to explore the ability of ionic liquids to act as a reactant, solvent, and surfactant, as a function of other synthesis parameters, also denoted as ionic liquid precursors (or task-special ionic liquids), which offer many advantages over traditional solution-phase methods. We then examine the design and fabrication of functional inorganic materials by means of optimizing the effect models of ionic liquids. Many of the most recent advances in ionothermal or ionic liquid-assisted synthesis have been realized by appropriate choice of cations or anions of ionic liquids according to the need. This review also highlights crucial issues that should be addressed in future research activities. This journal is © 2014 The Royal Society of Chemistry.

Guo Z.,Hunan University | Wang J.,Chinese University of Hong Kong | Yan Z.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks and Learning Systems | Year: 2014

This paper presents new theoretical results on the invariance and attractivity of memristor-based cellular neural networks (MCNNs) with time-varying delays. First, sufficient conditions to assure the boundedness and global attractivity of the networks are derived. Using state-space decomposition and some analytic techniques, it is shown that the number of equilibria located in the saturation regions of the piecewise-linear activation functions of an n-neuron MCNN with time-varying delays increases significantly from 2 n to 22n2+n22n2(times}) compared with that without a memristor. In addition, sufficient conditions for the invariance and local or global attractivity of equilibria or attractive sets in any designated region are derived. Finally, two illustrative examples are given to elaborate the characteristics of the results in detail. © 2013 IEEE.

Yang M.-G.,Central South University | Li C.-Y.,T.Y. Lin. International Engineering Consulting China CO. | Chen Z.-Q.,Hunan University
Engineering Structures | Year: 2013

Non-linear hysteresis is a complicated mechanical characteristic for magneto-rheological (MR) damper. In this paper, a new simple non-linear hysteretic model for MR damper is proposed to represent the hysteretic behavior. First, the force-displacement and force-velocity loops under a range of currents, amplitudes and frequencies are obtained by mechanical behavior test of a RD1097 type MR damper. Then the model's parameters are identified by the non-linear least square method from test data and fitted by the polynomials as functions of the supplied current. Finally, the accuracy and the effectiveness of the model are demonstrated by the RMS errors comparison between the reconstructed hysteretic curves and the experimental ones, and further are verified by seismic response reduction experiment under three excitations including the sinusoidal wave, the Pingsheng Bridge earthquake wave and the El-Centro wave. The results show that the proposed model has higher accuracy than some of existing models with explicit functions and is easier to be identified than those models with non-linear differential equations. Therefore, the proposed model can be effectively applied to simulation analysis in engineering control subjected to frequency-fixed or random excitations. © 2013 Elsevier Ltd.

Zhou J.,Hunan University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2012

To analyse the HPLC fingerprint of BYHW decoction extract. HPLC fingerprint of ten BYHW decoction extracts were established to calculate correlation parameter by total quantum statistcol moment (TQSM). The TQSM's parameters of ten BYHW decoction extract, such as AUC(T) was 1.976 x 10(7) microV x s, AUCPW(T) was 3.807 x 10(4) microV x s/mg, MCRT(T) was 13.72 min, VCRT(T) was 15.74 min2, and total quantum concentration was 519.0 mg/mL CONCLUSION: The total quantum statistic moment can be used to characterize the curve of chromatographic fingerprints with expressive parameters above, also to quantitative analyses by AUC(T) and qualitative analyses by AUCPW(T), MCRT(T) and VCRT(T).

Guo Z.,Hunan University | Guo Z.,Chinese University of Hong Kong | Wang J.,Chinese University of Hong Kong | Yan Z.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks and Learning Systems | Year: 2014

This paper presents new theoretical results on the passivity and passification of a class of memristor-based recurrent neural networks (MRNNs) with time-varying delays. The casual assumptions on the boundedness and Lipschitz continuity of neuronal activation functions are relaxed. By constructing appropriate Lyapunov-Krasovskii functionals and using the characteristic function technique, passivity conditions are cast in the form of linear matrix inequalities (LMIs), which can be checked numerically using an LMI toolbox. Based on these conditions, two procedures for designing passification controllers are proposed, which guarantee that MRNNs with time-varying delays are passive. Finally, two illustrative examples are presented to show the characteristics of the main results in detail. © 2014 IEEE.

Bai Z.P.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2010

To explore the clinical effects of bronchial arterial infusion (BAI) with oleum fructus bruceae (OFB) Injection and chemotherapeutic agents (CTA) in treating advanced non-small cell lung cancer (NSCLC). One hundred and three patients with advanced NSCLC were randomized into 2 groups, the 98 patients in the treatment group treated by BAI with OFB + CTA and the 50 in the control group by BAI with CTA alone. The incidence of adverse reaction, change of tumor size and patients' quality of life (QOL) in the two groups were observed and compared. The objective effective rate (CR + PR) was 63.3% in the treatment group and 46.0% in the control group (P < 0.01); the median survival duration in them was 363 days and 305 days; the 1-year cumulative survival rate was 70.4% and 44.0%, and the QOF improving rate was 83.7% and 62.0% respectively, the difference between groups were all statistically significant (P < 0.01). In addition, the incidence of adverse reactions of digestive symptoms, bone marrow suppression and the hepato-, renal and cardiac toxicities were lower in the treatment group than those in the control group (P < 0.01). BAI with OFB + CTA in treating NSCLC could enhance the objective therapeutic effect of simple chemotherapy, as well as raise the QOL and protect immune and medulla function in patients.

Jian W.X.,Hunan University
Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine / Zhongguo Zhong xi yi jie he xue hui, Zhongguo Zhong yi yan jiu yuan zhu ban | Year: 2010

To research the plasmic metabolites and metabolic pathway of Xin-blood stasis syndrome (XBSS). Plasma metabolic products in patients of coronary heart disease (CHD) with XBSS or non-XBSS and subjects in the control group were identified by gas chromatographic mass spectrometry (GC-MS) type QP2010, the changes of their main elements in different groups were analyzed by principal components analysis (PCA) and partial least squares (PLS) analysis. PCA showed that as compared with that in the control group, in the CHD-XBSS group, contents of lactic acid, beta-hydroxy butanoic acid, urea, oleic acid, octadecanoic acid and arachidonic acid were higher and that of citric acid was lower. PLS analysis showed significant difference between the control group and the other two groups, and the latter two groups tend to be of a same category. The occurrence of XBSS was positively correlated with octadecanoic acid, arachidonic acid, urea, lactic acid and beta-hydroxy, butanoic acid contents, and negatively correlated with oleic acid, L-proline, glycine, and citric acid contents. According to VIP, the degree of correlation between variables with drug interven- tion, from high to low, were ranked as arachidonic acid, octadecanoic acid, lactic acid, urea, beta-hydroxy butanoic acid, linoleic acid, glucose, alanine, oleic acid and proline. Discrepancy analysis on 11 changeful metabolites showed that the contents of arachidonic acid, octadecanoic acid, lactic acid, urea, beta-hydroxy butanoic acid and oleic acid increased in CHD patients, especially in those with XBSS (P < 0.01). In CHD patients, contents of lactic acid, beta-hydroxy butanoic acid, linoleic acid and glucose in patients of XBSS pattern were higher than in non-XBSS pattern (P < 0.01); content of linoleic acid, glucose, alanine and proline decreased in non-XBSS pattern while increased in XBSS pattern. Content of glucose in CHD-XBSS patients was significantly higher than that in the healthy control (P < 0.01). Content of citric acid was lower in CHD patients, and showed significant difference between that in CHD-XBSS patients and healthy control (P < 0.01). The major plasmic metabolites in CHD-XBSS patients are arachidonic acid, octadecanoic acid, lactic acid, urea, citric acid, beta-hydroxybutyric acid, oleic acid, glucose, and alanine. Analyzed from plasmic metabolite spectrum view, CHD-XBSS is related with lipid metabolism and glyco-metabolism, also with the stress induced by hypoxia and agonia.

Agency: Cordis | Branch: FP7 | Program: CP-FP-SICA | Phase: HEALTH.2010.1.1-3 | Award Amount: 4.87M | Year: 2011

Protein glycosylation is a post-translational phenomenon that is involved in most physiological and disease processes including cancer. Most of the known cancer-associated glycobiomarkers were discovered individually using liquid chromatography and mass spectroscopy. Though valuable, there is room for improvement in these approaches for the discovery phase. There is also a critical need for innovative, rapid, and high-throughput (HTP) technologies that will translate the discovery of cancer-associated glycobiomarkers from basic science to clinical application. The GlycoHIT consortium brings a highly experienced, innovative and interdisciplinary team of researchers from Europe, China and USA representing academia, industry and clinical fields to significantly enhance some of the existing glycoanalytical technologies and to advance novel HTP glycoanalytical technologies beyond current state of the art. Microchip technology and novel partitioning methods will be exploited for nanoscale HTP separations of serum glycoproteins for analysis by HPLC or LCMS. In parallel, lectin array technology will be radically improved by the innovative use of recombinant human lectins and lectin mimics derived by screening large phage displayed combinatorial libraries. Aptamer libraries will be exploited for identification of lectin mimics and development of a glycosignature platform Compatibility of the lectin/lectin mimic array technologies with novel label-free biosensors will be explored. Newly-developed technologies will be validated by analysis of serum samples from a variety of cancer patient cohorts and will be supported throughout by experimental interaction analysis, complex structural modelling and informatics. Effective project management, commercially-aware intellectual property management and targeted dissemination activities supplement the core science and ensure maximum impact for the project.

News Article | December 9, 2015
Site: www.techtimes.com

A new report revealed that glaciers on Mount Everest have dropped by 28 percent over the last 40 years. The report was made by researchers from Chinese Academy of Sciences, Mount Qomolangma Snow Leopard Conservation Center and Hunan University of Science and Technology. Researcher Kang Shichang from CAS's State Key Laboratory of Cryospheric Sciences said the report findings involve information collated on longitudinal investigations. The said analyses were performed both via remote sensing and actual on-site evaluation. Aside from the shrinking glaciers, the report also said that Mount Everest or Mount Qomolangma in Tibet has been exuding warmer temperatures in the last 50 years. Then and Now "The glacial shrinkage area is compared to the measurements taken in the 1970s," the press release read. For the rate of glacial shrinkage in the south slope of the mountain, the researchers found a 26 percent decrease. Now, the nature reserve of the mountain has about 1,476 glaciers, which covers 2,030 square kilometers. Kang, who has led multiple glacier investigation groups, said the consequences of shrinking glaciers are the development of wide glacial lakes and higher levels of rivers. As per remote sensing, the size of the glacial lake in the mountain's nature reserve increased from 100 square kilometers in 1990 to 114 square kilometers in 2013. Located between Nepal and China, Mount Everest is the world's largest mountain, standing 8,844 meters high. Large Asian rivers such as those in Ganges and Brahmaputra have the mountain as its source. In May 2015, international experts warned that the 5,500 glaciers in the Hindu Kush- Himalayan (HKH) area may plummet by 70 to 99 percent come the year 2100. HKH is the home of tallest peaks in the world. If the predicted glacial drop persists, farming and hydropower supply may also be affected.

Wang H.,Hunan University | Li G.Y.,Hunan University | Li E.,Central South University
Computer Methods in Applied Mechanics and Engineering | Year: 2010

In automotive industry, structural optimization for crashworthiness criteria is of special importance in the early design stage. To reduce the vehicle design cycle, metamodeling techniques have become so widespread... In this study, a time-based metamodeling technique is proposed for the vehicle design. The characteristics of the proposed method are the construction of a time-based objective function and establishment of a metamodel by support vector regression (SVR). Compared with other popular metamodel-based optimization methods, the design space of the proposed method is expanded to time domain. Thus, more information and features can be extracted in the expanded time domain. To validate the performance of the time-based metamodeling technique, cylinder impacting and full vehicle frontal collision are optimized by the proposed method. The results demonstrate that the proposed method has potential capability to solve the crashworthiness vehicle design. © 2010 Elsevier B.V.

Chen M.,Hunan University | Tan Z.,Hunan University | Zeng G.,Hunan University | Zeng Z.,Central South University
Infection, Genetics and Evolution | Year: 2012

Compound microsatellites consist of two or more individual microsatellites, and may originate from dynamic mutations or imperfection of microsatellites. Previous studies have found microsatellites were present in 81 completed Human Immunodeficiency Virus Type 1 (HIV-1) genomes, suggesting compound microsatellites may exist in viral genomes. However, up to now, compound microsatellites have not been analyzed in any viral genomes. We identified and characterized 238 compound microsatellites in 81 completed HIV-1 genomes. About 0-24.24% of all microsatellites could be categorized as compound microsatellites. Compound microsatellite distribution is very different in two aspects between diverse HIV-1 genomes. First, the number and motifs of compound microsatellites are variable between surveyed genomes. Second, the relative abundance and relative density of compound microsatellites exhibit very significant differences between these surveyed genomes, respectively. The relative abundance and relative density of compound microsatellites were weakly correlated with genome size and microsatellite density. We observed a more dynamic picture of compound microsatellites than previously reported in eukaryotes. This might be attributed to the lack of proofreading in HIV-1 genomes, as it has been demonstrated that the loss of polymerase proofreading activity can greatly enhance the mutation rate of microsatellites. © 2012 Elsevier B.V.

Wang H.,Hunan University | Li E.,Central South University | Li G.Y.,Hunan University
Computational Mechanics | Year: 2011

This paper presents a crashworthiness design optimization method based on a metamodeling technique. The crashworthiness optimization is a highly nonlinear and large scale problem, which is composed various nonlinearities, such as geometry, material and contact and needs a large number expensive evaluations. In order to obtain a robust approximation efficiently, a probability-based least square support vector regression is suggested to construct metamodels by considering structure risk minimization. Further, to save the computational cost, an intelligent sampling strategy is applied to generate sample points at the stage of design of experiment (DOE). In this paper, a cylinder, a full vehicle frontal collision is involved. The results demonstrate that the proposed metamodel-based optimization is efficient and effective in solving crashworthiness, design optimization problems. © 2010 Springer-Verlag.

Yang L.,Hunan University | Chen B.,Hunan University | Luo S.,Hunan University | Li J.,Hunan University | Liu R.,Hunan University
Environmental Science and Technology | Year: 2010

CdTe quantum dots (QDs) are prepared on TiO2 nanotubes (TiO 2 NTs), for the first time, with pulse electrodeposition. A novel single-drop optical sensor is prepared with the CdTe QDs-modified TiO 2 NTs, and applied for the detection of polycyclic aromatic hydrocarbons (PAHs) based on fluorescence resonance energy transfer (FRET). Excited at 270 nm, the sensor shows fluorescence emission at around 370 nm. As PAHs are with absorption/fluorescence emission at around 364/410 nm, FRET happens between the CdTe QDs and PAHs with the CdTe QDs as donors and PAHs as receptors. The sensitivity is dependent on the number of rings of the PAHs, with the highest sensitivity observed in the response to benzo(a)pyrene (BaP). Using FRET, the sensitivity to BaP is enhanced by about 2 orders with respect to the direct fluorescent spectrometry. The proposed sensor shows a linear response to the logarithm of BaP concentration in the range of 400 nM to 40 pM, with a detection limit of 15 pM, which is much close to the quality criteria (15.1 pM) in drinking water set by U.S. Environment Protection, suggesting that the proposed sensor can be used for quick scanning of PAHs. The achieved sensitivity is much higher than that of the published sensor-based methods. As PAHs are quantified based on the relative fluorescence intensity at 410-370 nm, the sensor need no calibration with a standard sensor, avoiding the influence from the sensor-to-sensor difference. The practicability of the sensor is tested by analyzing PAHs in Xiangjiang River water, the PAHs contents ranges from 0.045 to 2.847 ng/L based on the sampling spots. © 2010 American Chemical Society.

Chen M.,Hunan University | He J.,Hunan University | Tang J.,Hunan University | Wu X.,Beijing Jiaotong University | Chen L.,Hunan University
Optics Express | Year: 2014

In this paper, a FPGAs-based real-time adaptively modulated 256/64/16QAM-encoded base-band OFDM transceiver with a high spectral efficiency up to 5.76bit/s/Hz is successfully developed, and experimentally demonstrated in a simple intensity-modulated direct-detection optical communication system. Experimental results show that it is feasible to transmit a raw signal bit rate of 7.19Gbps adaptively modulated real-time optical OFDM signal over 20km and 50km single mode fibers (SMFs). The performance comparison between real-time and off-line digital signal processing is performed, and the results show that there is a negligible power penalty. In addition, to obtain the best transmission performance, direct-current (DC) bias voltage for MZM and launch power into optical fiber links are explored in the real-time optical OFDM systems. © 2014 Optical Society of America.

Li C.C.,Hunan University | Zheng Y.P.,Xiamen University | Wang T.H.,Hunan University
Journal of Materials Chemistry | Year: 2012

In this work, we reported several kinds of highly stable, effective mesoporous Au/TiO 2 sphere-based solid acid catalysts with large specific surface areas and good monodispersity in the reaction medium. In this process, monodisperse titanium glycolate spheres were first formed by an antisolvent precipitation route, and were then converted to mesoporous TiO 2 by in situ hydrolysis under hydrothermal conditions. The resultant uniform TiO 2 spheres were subsequently functionalized with sulfate anions at different temperatures or incorporated with tungstophosphoric acid (TPA); the solid acid catalysts were thus fabricated. In particular, our monodisperse spherical catalysts with large specific surface area have shown remarkable performance in a wide range of acid-catalyzed reactions such as Friedel-Crafts alkylation, esterification and hydrolysis of acetate. The TiO 2-based catalysts could be separated and reused showing no deactivation. © 2012 The Royal Society of Chemistry.

Ma J.,Hunan University | Wang T.,Hunan University
Journal of Alloys and Compounds | Year: 2014

The paper reports the fabrication of microscale NiO matrixes with enhanced electrochemical properties through annealing the corresponding chrysanthemum-like a-Ni(OH)2 microspheres. The precursor a- Ni(OH)2 can be synthesized by a hydrothermal method using triethanolamine as the alkaline source. The formation mechanism of chrysanthemum-like a-Ni(OH)2 microspheres is properly discussed. Furthermore, the electrochemical experiments demonstrate that the microscale NiO matrixes show superior electrochemical behavior in lithium-ion batteries due to their unique structures. © 2013 Elsevier B.V. All rights reserved.

Yang D.-R.,Hunan University | Zhu H.-Z.,Hunan University | Zhu H.-Z.,Central South University
World Journal of Gastroenterology | Year: 2015

Hepatitis C virus (HCV) is a major human pathogen of chronic hepatitis and related liver diseases. Innate immunity is the first line of defense against invading foreign pathogens, and its activation is dependent on the recognition of these pathogens by several key sensors. The interferon (IFN) system plays an essential role in the restriction of HCV infection via the induction of hundreds of IFN-stimulated genes (ISGs) that inhibit viral replication and spread. However, numerous factors that trigger immune dysregulation, including viral factors and host genetic factors, can help HCV to escape host immune response, facilitating viral persistence. In this review, we aim to summarize recent advances in understanding the innate immune response to HCV infection and the mechanisms of ISGs to suppress viral survival, as well as the immune evasion strategies for chronic HCV infection. © 2015 Baishideng Publishing Group Inc. All rights reserved.

Duan M.-Y.,Hunan University | Liang R.,Hunan University | Tian N.,Xiamen University | Li Y.-J.,Hunan University | Yeung E.S.,Hunan University
Electrochimica Acta | Year: 2013

Au-Pt core-shell nanoparticles (Au-Pt NPs) as an effective bimetallic electrocatalyst for methanol oxidation has been extensively explored. However, the conventional drop-coating method for fabricating Au-Pt NP electrodes did not fully exploit the small size of the NPs. Here, self-assembly of Au-Pt NPs into monolayer arrays is proposed as an alternative for the preparation of Au-Pt NP catalytic electrode to ensure the exposure of each NP to electrolyte. Under the optimized condition, the Pt mass activity of the Au-Pt monolayer array was ∼6 times better than that of the commercial Pt/C catalyst, and 3 times better than that of Au-Pt NP electrodes fabricated by a drop-coating method, indicating superior electrocatalytic activity. © 2012 Elsevier Ltd.

Huang J.,Hunan University | Wu Y.,University of Florida | Chen Y.,Hunan University | Zhu Z.,University of Florida | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2011

Make it a double: Complementary probes with two pyrene labels were engineered for the amplification of a target DNA sequence. In the stem-closed conformation of the probes in the absence of the target, the two pyrene moieties were separated. The target propagated hybridization chain reactions to bring pyrene moieties on neighboring probes close together to form fluorescent pyrene excimers (see picture). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.