Showing papers by "Hengyang Normal University published in 2011"
TL;DR: A unique 4-fold interpenetrated (10,3)-b copper(II) framework exhibits reversible dehydration and rehydration in a single-crystal-to-single-Crystal (SC-SC) process, and the dehydrated material can encapsulate CH(3)OH molecules in a SC-SC fashion.
100 citations
TL;DR: In this article, a highly sensitive and mercury-free method for determination of bisphenol A (BPA) was established using a glassy carbon electrode that was modified with carboxylated multi-walled carbon nanotubes.
Abstract: A highly sensitive and mercury-free method for determination of bisphenol A (BPA) was established using a glassy carbon electrode that was modified with carboxylated multi-walled carbon nanotubes. A sensitive oxidation peak is found at 550 mV in linear sweep voltammograms at pH 7. Based on this finding, trace levels of bisphenol A can be determined over a concentration range that is linear from 10 nM to 104 nM, the correlation coefficient being 0.9983, and the detection limit (S/N = 3) being 5.0 nM. The method was successfully applied to the determination of BPA in food package.
79 citations
TL;DR: In this article, a pathway to open the band gap of graphene by p-n codoping is presented according to the first principles study, and two models are used: Lithium adsorbed on Boron-doped graphene (BG) and Boron−Nitrogen (B/N) codoping into graphene.
78 citations
TL;DR: Using ab-initio density functional theory calculations, Wang et al. as mentioned in this paper investigated the adsorption abilities of ten molecules (O2, H2, N2, CO, NO, H 2O, CO2, NO2, SO2 and NH3) on pristine and C-doped graphene-like boron nitrogen (g-BN) sheet.
Abstract: Using ab-initio density functional theory calculations, we investigated the adsorption abilities of ten molecules (O2, H2, N2, CO, NO, H2O, CO2, NO2, SO2 and NH3) on pristine and C-doped graphene-like boron nitrogen (g-BN) sheet. We found that (1) these ten molecules only physisorbed on g-BN; (2) C doping changed the adsorption properties of g-BN and could induce the stable chemisorption of O2, NO, NO2, CO2 and SO2 (depending on the defect types) onto the g-BN sheet; (3) C doping could not change the adsorption behavior of N2, H2, CO, H2O and NH3. After chemisorption, the electronic structures of systems were also affected judging from the electronic density of state calculations. Interestingly, due to the different adsorbate, the g-BN has different magnetic momentum which mainly came from p orbital of O, C or S atom. This research suggests that doping could be an efficient method to control or improve the physical properties (electronic, magnetic) of certain materials. C-doped g-BN also could be directly applied in gas sensing field.
41 citations
TL;DR: In this paper, a nonlocal boundary value problem of impulsive fractional differential equations is studied and sufficient conditions for the existence of at least one solution of the problem are established by means of a fixed point theorem due to O'Regan.
Abstract: We study a nonlocal boundary value problem of impulsive fractional differential equations. By means of a fixed point theorem due to O'Regan, we establish sufficient conditions for the existence of at least one solution of the problem. For the illustration of the main result, an example is given.
39 citations
TL;DR: The developed electrochemical sensor has been successfully applied for the determination of tryptophan in pharmaceutical and biological samples with satisfactory assay results and the linearity between the anodic peak currents and concentrations of Trp demonstrated a wide range.
Abstract: Chitosan was modified by salicylaldehyde via Schiff's base reaction and the resulting product was modified on the surface of an acetylene black paste electrode (ABPE) by the drop-coating method. In 0.5 mol L(-1) acetate buffer (pH 4.2), a substantial increase in the anodic stripping peak current of tryptophan (Trp) (compared to conventional bare carbon paste electrode (CPE) and bare ABPE) is observed at the Schiff's base chitosan-modified electrode. The parameters influencing voltammetric determination of Trp have been optimized. Under the selected conditions, the linearity between the anodic peak currents and concentrations of Trp demonstrated a wide range of 6.0 × 10(-8) mol L(-1) to 2.0 × 10(-6) mol L(-1), 2.0 × 10(-6) mol L(-1) to 4.0 × 10(-5) mol L(-1) and 4.0 × 10(-5) mol L(-1) to 1.0 × 10(-4) mol L(-1), a low detection limit of 2.0 × 10(-9) mol L(-1) was obtained after a 60 s accumulation. In addition, the developed electrochemical sensor has been successfully applied for the determination of Trp in pharmaceutical and biological samples with satisfactory assay results.
39 citations
TL;DR: In this article, the existence and multiplicity of solutions for fourth-order impulsive differential equations were studied using variational methods and critical point theory, and some new criteria to guarantee that the impulsive problem has at least one nontrivial solution, infinitely many distinct solutions under some different conditions, respectively.
Abstract: Many dynamical systems have impulsive dynamical behaviors due to abrupt changes at certain instants during the evolution process. The mathematical description of these phenomena leads to impulsive differential equations. In this paper, we study the existence and multiplicity of solutions for fourth-order impulsive differential equations. By using the variational methods and critical point theory, we give some new criteria to guarantee that the impulsive problem has at least one nontrivial solution, infinitely many distinct solutions under some different conditions, respectively. Some examples are given in this paper to illustrate the feasibilities of our main results.
34 citations
TL;DR: In this paper, the existence of positive solutions for the Schrodinger-Poisson system (SP) when the nonlinearity f has growth at most linear for λ small, allowing the potential V(x) to vanish at infinity.
Abstract: In this paper, we study the Schrodinger–Poisson system
(SP){−Δu+V(x)u+λϕ(x)u=K(x)f(u),inR3,−Δϕ=u2,u>0,inR3,
and prove the existence of positive solutions for system (SP) when the nonlinearity f has growth at most linear for λ small, allowing the potential V(x) to vanish at infinity. In addition, also we obtain the nonexistence of a nontrivial positive solution for λ≥14.
32 citations
TL;DR: Using variational methods and a three-critical-point theorem, sufficient conditions are established under which a fourth-order differential system possesses two solutions generated from a boundary condition.
30 citations
TL;DR: In this article, two new 3D coordination polymers [Zn(INAIP)]·2DMF (1) and Zn(NO3)2·6H2O with 5-(isonicotinamido)isophthalic acid (H2INAIP) in N,N-dimethylformamide (DMF) and N, N-diethyl formamide (DEF), respectively, have been synthesized by reactions of ZnNO32.
30 citations
TL;DR: In this paper, a reliable and sensitive procedure for the determination of trace levels of molybdenum by adsorptive anodic stripping voltammetry is proposed, which is based on the accumulation of the Mo-alizarin violet (AV) complex onto an acetylene black paste electrode (ABPE), followed by oxidation of the adsorbed species by voltammetric scan using a second-order derivative modulation.
TL;DR: A zeroth order approximation is used to describe the evolution of the environment radon concentration, and a novel algorithm is obtained for quick and continuous tracing the change of Radon concentration.
Abstract: Several measurements of the radon concentration are performed by RAD7 in the University of South China. We find that 30-40 min is needed for RAD7 for tracing the concentration of the standard radon chamber. There are two reasons. The first is that the sufficient time of air cycle is needed for the radon concentration in internal cell of RAD7 equal to that of the environment; and the second is that the sufficient decay time is needed for the (218)Po concentration in internal cell of RAD7 equal to that of the radon. We used a zeroth order approximation to describe the evolution of the environment radon concentration, and obtained a novel algorithm for quick and continuous tracing the change of radon concentration. The corrected radon concentration obtained through this method is in good agreement with the reference value. This method can be applied to develop and improve the instruments for tracing the change of radon concentration quickly.
TL;DR: In this article, a sensitive procedure was developed for the determination of trace molybdenum(VI) by adsorptive anodic stripping voltammetry based on the oxidation of 2′,3,4,4′,5,7-pentahydroxyflavone (morin) complex at a sodium dodecyl sulfate modified carbon paste electrode (denoted as SDS/CPE).
TL;DR: In this article, the existence of infinitely many homoclinic solutions for a class of second order Hamiltonian systems was investigated and the fountain theorem due to Zou was used to obtain two new criteria for guaranteeing that second-order Hamiltonians have infinitely many solutions.
Abstract: In this paper, we investigate the existence of infinitely many homoclinic solutions for a class of second order Hamiltonian systems. By using fountain theorem due to Zou, we obtain two new criteria for guaranteeing that second order Hamiltonian systems have infinitely many homoclinic solutions. Recent results in the literature are generalized and significantly improved.
TL;DR: In this paper, it was shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations.
Abstract: Remote information concentration (RIC) in $d$-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found; i.e., they have ${d}^{2}$ common commuting stabilizers. The differences of qudit-RIC and qubit-RIC ($d=2$) are also analyzed.
TL;DR: Previous evaluation methods using AHP, principal component analysis, BP neural network and expert scoring method on quantitative assessment and analysis are drawn on, then clustering the results by comparison to determine which method to evaluate the most accurate.
Abstract: In the paper, Authors separately used analytical hierarchy process, expert scoring method, principal component and BP network to establish the weights of ecological vulnerability evaluation Index system in the Hengyang Basin as a case, and used hierarchical-comprehensive index -clustering model, principal component-comprehensive index- clustering analysis model, expert scoring-composite index-clustering analysis model, BP artificial neural network model to evaluate separately the reality vulnerability in 2000. The results shows that study area are moderate weak, and the results broadly similar. Authors think that Principal component and artificial neural network model can avoid subjective factors, and taking the way of the expert group judgment is to reduce the error of ecological vulnerability assessment. With the impact of global change and the strengthening of fragile ecosystems, China has carried out many researches and practices on vulnerability assessments [1,14].Although Vulnerability assessment in many ways, not yet formed a unified evaluation method, this paper draw on previous evaluation methods based on [1,11], using AHP, principal component analysis, BP neural network and expert scoring method on quantitative assessment and analysis, then clustering the results by comparison to determine which method to evaluate the most accurate.Authors analysis the Hengyang Basin reality vulnerability in 2000,attempting to explore a more suitable and easy erosion in hilly areas degraded fragile vulnerability assessment method.
TL;DR: The main purpose of the present paper is to derive some properties associated with the neighborhoods and partial sums of a certain class of meromorphic multivalent functions.
TL;DR: In this paper, a carbon paste electrode was modified with a binuclear manganese(II) complex by the drop-coating method, and the mechanism of the electro-oxidation of tryptophan (Trp) at this electrode indicated that it enables Trp to be determined with good sensitivity and selectivity.
Abstract: We report on a carbon paste electrode that was modified with a binuclear manganese(II) complex by the drop-coating method. A study on the mechanism of the electro-oxidation of tryptophan (Trp) at this electrode indicated that it enables Trp to be determined with good sensitivity and selectivity. Second-order derivative linear sweep voltammetry at pH 4.1 revealed that a sensitive anodic peak appears at 812 mV (vs. SCE) whose current is proportional to the concentration of Trp in the concentration range from 0.1 to 1.0 μmol L−1 and 1.0 to 80 μmol L−1, with a detection limit (S/N = 3) of 0.08 μmol L−1 (60 s of accumulation). The method was applied to the determination of Trp in amino acid injection solutions with satisfactory results.
TL;DR: In this paper, a theoretical model for an all-in-one thin film silicon solar cell (TFSSC) design with the anti-reflection (AR) coatings, the transparent electrodes, the silicon and the back reflective coatings all deposited on one piece of glass is proposed and the optical performance for the design is numerically simulated.
TL;DR: In this article, a pyridine bridged cyclodextrin dimer mono-copper complex (CuL) was synthesized and characterized for the catalytic performance of carboxylic acid esters.
TL;DR: In this paper, a new ligand (L), 6-mono-(2-hydroxy-3-(hydroxymethyl)-5-methyl benzylamino)-ethylamino), β-cyclodextrin, based on β-cycle derivatives with dinucleating units was synthesized and used to prepare a trimetallic bis-ligands zinc complex (Zn 3 (L 2− ) 2 ).
Abstract: A new ligand (L), 6-mono-(2-(2-hydroxy-3-(hydroxymethyl)-5-methyl benzylamino)-ethylamino)-β-cyclodextrin, based on β-cyclodextrin derivatives with dinucleating units was synthesized and used to prepare a trimetallic bis-ligands zinc complex (Zn 3 (L 2− ) 2 ). The esterase activity of the complex was investigated by the hydrolysis of two carboxylic acid esters, bis(4-nitrophenyl)carbonate (BNPC) and 4-nitrophenyl acetate (NA), and a DNA model bis(4-nitrophenyl)phosphate (BNPP) as a phosphate ester. The catalytic rate for BNPC was very high, which was found to be a 5.63 × 10 3 -fold rate enhancement over uncatalyzed hydrolysis and 1.62 × 10 2 -fold rate enhancement over uncatalyzed hydrolysis for NA hydrolysis at pH = 7.0. For the catalytic hydrolysis of BNPP, the initial first-order rate constant of 0.1 mM catalyst was 5.85 × 10 −8 s −1 at pH = 8.50 and 35 °C, which is a 731-fold acceleration over uncatalyzed hydrolysis. The second rate constant ( k BNPP ) was found to be 1.22 × 10 −3 M −1 s −1 at pH = 10.0. According to the potentiometric titration study, the zinc complex exists in a dinuclear single ligand coordinated mode and a trinuclear bis-ligands system at pH ≥ 7.0. The ester hydrolysis activity was attributed to the cooperative interaction of the two metal centers and the hydrophobic cavity of β-cyclodextrin with substrates.
TL;DR: In this paper, an explicit formula for a lower bound for the volumes of complex hyperbolic orbifolds depending on the dimension and the maximal order of torsion elements in their fundamental groups is obtained.
Abstract: In this paper, an explicit formula for a lower bound for the volumes of complex hyperbolic orbifolds depending on the dimension and the maximal order of torsion elements in their fundamental groups is obtained. This generalizes Adeboye (Pac. J. Math. 237:1–19 2008, Theorem 1) to the setting of complex hyperbolic spaces.
TL;DR: In this article, a plausible formation mechanism of disordered CdSe nanowires is proposed, and an intense red near-band edge emission is observed based on room temperature photoluminescence measurements of individual nanowire.
Abstract: Disordered CdSe nanowires have been successfully grown on silicon substrates by Au-catalyzed vapor–liquid–solid (VLS) mechanism. Scanning electron microscopy (SEM) reveals that the as-prepared products consist of a large quantity of 1D nanowire disordered predominantly perpendicular to the surface of the substrate. A plausible formation mechanism of disordered CdSe nanowires is proposed here. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirm on their hexagonal wurtzite crystallite structure. An intense red near-band edge emission (702 nm) is observed based on room temperature photoluminescence measurements of individual nanowire. This kind of CdSe nanostructures may be used in optoelectronics devices in the near future.
TL;DR: This work presents optical multiple input and multiple output (MIMO) communication system to achieve high data rate, which can mitigate the shadow effect of indoor communication and simulates the MIMO system with adaptive equalization.
Abstract: Light emitting diode (LED) is one of the most important light sources in the 21st century and has broad prospects in the illumination. Currently, the white LED is used not only for illumination, but also for transmission data. A new technique referred as visible light communication (VLC) is rapidly growing in optical communication. In order to enhance the performance of the communication link, we present optical multiple input and multiple output (MIMO) communication system to achieve high data rate, which can mitigate the shadow effect of indoor communication. Moreover, the MIMO will bring about multi-path effect, which causes inter-symbol interference (ISI) to degrade the performance of the link. Hence, an adaptive equalization technique has been used in the receiver system, which can reduce the ISI when the system is determined to receive symbol. Finally, we have simulated the MIMO system with adaptive equalization. The simulation results show significant improvement in the transmission rate using on off keying (OOK) and the average signal to noise ratio (SNR) in this channel has increased 13.5 dB after equalization.
TL;DR: In this article, a 3D-4f heterometallic coordination polymer, [CuGd2(INAIP)3(HCOO)(H2O)3]·3 H2O (1), has been synthesized and characterized by single crystal X-ray diffraction analysis.
TL;DR: In this paper, the adsorptive voltammetric behavior of the aluminum-alizarin violet (AV) complex in 0.2 ǫ L−1 HAc-NaAc buffer (pH 4.5) at a multi-walled carbon nanotube modified carbon paste electrode (MWCNT/CPE) was investigated.
Abstract: The adsorptive voltammetric behavior of the aluminum (Al)-alizarin violet (AV) complex in 0.2 mol L−1 HAc-NaAc buffer (pH 4.5) at a multi-walled carbon nanotube modified carbon paste electrode (MWCNT/CPE) was investigated. The results showed that the complex can be adsorbed on the surface of the MWCNT/CPE, yielding one oxidation peak at 530 mV (vs. SCE). The proposed method exhibits good linearity over the range from 1.0 × 10−9 mol L−1 to 1.0 × 10−7 mol L−1, and a low detection limit of 6.0 × 10−10 mol L-1 for 120 s accumulation was obtained under optimum conditions.
TL;DR: In this article, six new 3D-4f heterometallic coordination polymers have been synthesized and characterised by single crystal X-ray diffraction analysis, and the results revealed that the different transition metal centers have great influence on the structures of the resulted complexes in this system.
Abstract: Six new 3d-4f heterometallic coordination polymers, {[Ln4Cu2(INAIP)8(H2O)15]·14H2O}n [Ln = La (1), Pr (2), Nd (3)] and {[LnCo0.5(INAIP)2(H2O)2]·2H2O}n [Ln = Tb (4), Dy (5), Yb (6), H2INAIP = 5-(isonicotinamido)isophthalic acid] have been synthesised and characterised by single crystal X-ray diffraction analysis. The results of structural analyses showed that 1–3 are isomorphous showing two-fold interpenetrated three-dimensional (3D) coordination framework, while 4–6 have the same non-interpenetrated 3D structure with 2D (4, 4) lanthanide-carboxylate layers. The results revealed that the different transition metal centres have great influence on the structures of the resulted complexes in this system. In addition, thermogravimetric and magnetic properties of 1–6, and photoluminescence of 4 were investigated.
TL;DR: In this paper, the authors present a new approach for finding a stable solution of a system of nonlinear equations arising from dynamical systems, which is based on the concept of stability functions.
Abstract: In this paper, we present a new approach for finding a stable
solution of a system of nonlinear equations arising from dynamical
systems. We introduce the concept of
stability functions and use this idea to construct
stability solution models of several
typical small signal stability problems in dynamical systems.
Each model consists of a system of constrained
semismooth equations. The advantage of the new models is twofold.
Firstly, the stability requirement of dynamical systems is
controlled by nonlinear inequalities. Secondly, the semismoothness
property of the stability functions makes the models solvable by
efficient numerical methods. We introduce smoothing functions for
the stability functions and present a smoothing Newton method
for solving the problems. Global and local quadratic convergence of
the algorithm is established. Numerical examples from dynamical
systems are also given to illustrate the efficiency of the new
approach.
TL;DR: In this paper, the finite-temperature density functional theory and the quasiharmonic approximation are adopted to investigate thermodynamics properties of hexagonal osmium by varying lattice volume, the anharmonic effect is part considered.
Abstract: The finite-temperature density functional theory and the quasiharmonic approximation are adopted to investigate thermodynamics properties of hexagonal osmium. By varying lattice volume, the anharmonic effect is part considered in present work. Phonon frequencies calculations are performed from density functional perturbation theory (DFPT). By fitting the total free energy (including both electronic and vibrational parts) to equation of states at different temperatures, some classical thermodynamic quantities and their pressure and temperature dependences are investigated systematically. The results are in good agreement with the available experimental and theoretical data.
TL;DR: In this paper, the light trapping characteristics in the wavelength range of 0.5−1.2μm for the random back-reflective silicon film with omnidirectional top anti-reflection were numerically analyzed based on the simplified probability method.