Yufang Liu

Hu Nan Normal University, Ch’ang-sha-shih, Hunan, China

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Publications (57)65.54 Total impact

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    ABSTRACT: The excited-state properties of intramolecular hydrogen bonding in the compounds based on 2-(2-hydroxyphenyl)-1,3-benzoxazole (6 and its tautomers 6a and 6b) have been investigated using theoretical methods. According to the geometric optimization and IR spectra in the ground and excited states calculated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods respectively, the type of intramolecular hydrogen bonding N⋯HO in 6 and 6a is demonstrated to be significantly strengthened, while NH⋯O in the tautomers 6a and 6b are proved to be sharply weakened upon excitation to excited state S1. The calculated absorption peaks of 6 are in good accordance with the experimental results. Moreover, other compounds based on 6 that R1 and R2 are both substituted as well as that only R1 is substituted are investigated to understand the effect of substituent on intramolecular hydrogen bonding. It is found that the hydrogen bond strength can be controlled by the inductive field effect of the substituent. In addition, the intramolecular charge transfers (ICT) of the S1 state for 6 and its tautomers 6a and 6b were theoretically investigated by analyses of molecular orbital.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2014; 133C:818-824. · 1.98 Impact Factor
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    ABSTRACT: Ab initio scattering calculations for low-energy electron collisions with an open-shell molecule H2CN have been carried out using the R-matrix method. The elastic integral, differential, and momentum transfer cross sections and the excitation cross sections from the ground state to the three low-lying electron excited states are presented in the energy region of 0-10 eV. The results of the static exchange, correlated 1-state and 14-state close-coupling approximations are investigated to identify the low-lying resonant states of the anions formed due to electron capture by the radical. Four shape resonances and three core-excited shape resonances have been detected in the 14-state model. The Born-closure approximation is applied for the elastic and dipole-allowed transitions to account for the l > 4 partial waves excluded from the R-matrix calculations.
    01/2014; 89(2).
  • Dapeng Yang, Yonggang Yang, Yufang Liu
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    ABSTRACT: The geometrical and spectral properties of the hydrogen-bonded clusters formed by 6-aminocoumarin (6AC) with solvents of different hydrogen-bonding abilities have been investigated at the CPCM-PBE0/6-311++G(d, p) level of theory. Upon photoexcitation, A type hydrogen bonds will be weakened whereas hydrogen bonds of B and C types should be strengthened. The weakening of hydrogen bond A is responsible for the blue-shifts of the absorption spectra in HFIP and TFE while strengthening of hydrogen bonds B1 and B2 are the reasons for the red-shifts of the absorption spectra in DMSO. The absorption spectra of cluster 6AC–(H2O)3 is in better agreement with the experimental result than 6AC–(H2O)5, which dose not support the conjecture of E. Krystkowiak. Moreover, the stabilization effects of the different types of intermolecular hydrogen bonding on the absorption spectra properties of the hydrogen-bonded 6AC clusters are discussed in detail.
    Journal of Cluster Science 01/2014; 25(2). · 1.11 Impact Factor
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    ABSTRACT: We have reported the reaction probability, integral reaction cross section, and rate constant for the title system calculated with the aid of a time-dependent wave packet approach. The ab initio potential energy surface (PES) of Prudente et al. (Chem. Phys. Lett. 2009, 474, 18) is employed for the purpose. The calculations are carried out over the collision energy range of 0.05-1.4 eV for the two reaction channels of H + LiH Li + and + + . The Coriolis coupling (CC) effect are taken into account. The importance of including the Coriolis coupling quantum scattering calculations are revealed by the comparison between the Coriolis coupling and the centrifugal sudden (CS) approximation calculations.
    Bulletin- Korean Chemical Society 01/2014; 35(1). · 0.98 Impact Factor
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    ABSTRACT: The time-dependent density functional theory method was performed to investigate the excited-state hydrogen-bonding dynamics of N-(2-hydroxyethyl)-1,8-naphthalimide (2a) and N-(3-hydroxyethyl)-1,8-naphthalimide (3a) in methanol (meoh) solution. The ground and excited-state geometry optimizations, electronic excitation energies, and corresponding oscillation strengths of the low-lying electronically excited states for the complexes 2a + 2meoh and 3a + 2meoh as well as their monomers 2a and 3a were calculated by density functional theory and time-dependent density functional theory methods, respectively. We demonstrated that the three intermolecular hydrogen bonds of 2a + 2meoh and 3a + 2meoh are strengthened after excitation to the S1 state, and thus induce electronic spectral redshift. Moreover, the electronic excitation energies of the hydrogen-bonded complexes in S1 state are correspondingly decreased compared with those of their corresponding monomer 2a and 3a. In addition, the intramolecular charge transfer of the S1 state for complexes 2a + 2meoh and 3a + 2meoh were theoretically investigated by analysis of molecular orbital. Copyright © 2014 John Wiley & Sons, Ltd.
    Journal of Physical Organic Chemistry 01/2014; · 1.58 Impact Factor
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    ABSTRACT: The intermolecular hydrogen bonding dynamics between the functionalized activated carbons (AC) and ethyl mercaptan (ETM) were investigated using DFT and TDDFT methods, respectively. The ground-state and excited-state structures, electronic excitation energies and corresponding oscillation strengths of the low-lying electronically excited states for the functionalized ACs and their hydrogen-bonded complexes I, II, III and IV were calculated. It is demonstrated that the stability trend of forming hydrogen-bonded complexes is I > II and III > IV, which coincides with the results from the interaction energies calculation EHB. Moreover, according to Zhao's rule on the excited hydrogen bonding dynamics, it is found that the hydrogen bonds in the complexes I, II and III are significantly strengthened, with the excitation energy of a related excited state being red shifted, the hydrogen bond interactions can facilitate ETM adsorption onto AC-COOCO, AC-CCC and AC-CO, respectively. The intermolecular hydrogen bond of complex IV in the excited state is noteworthily weakened, in which the excitation energy of a related excited state is blue shifted. Therefore, the hydrogen bond interaction in complex IV is against ETM adsorption onto AC-OH in the excited state. The photoexcitation for complex IV should be controlled during the absorption process.
    Journal of Photochemistry and Photobiology A: Chemistry. 01/2014; 291:9–15.
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    ABSTRACT: Ab initio all-electron relativistic calculations of the low-lying excited states of Si2+ have been performed at MRCI+Q/AVQZ level. The calculated electronic states, including 12 doublet and 12 quartet Λ-S states, are correlated to the dissociation limit of Si(3Pg) + Si+(2Pu). Spin-orbit interaction is taken into account via the state interaction approach with the full Breit-Pauli Hamiltonian, which causes the entire 24 Λ-S states to split into 54 Ω states. This is the first time that spin-orbit coupling (SOC) calculation has been performed on Si2+. The obtained potential energy curves (PECs) of Λ-S and Ω states are respectively depicted with the aid of the avoided crossing rule between the same symmetry. The spectroscopic constants of the bound Λ-S and Ω states are determined, and excellent agreements with the latest theoretical results are achieved.
    Chemical Physics 11/2013; · 1.96 Impact Factor
  • Dapeng Yang, Yonggang Yang, Yufang Liu
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    ABSTRACT: In the present work, the charge transfer (CT) process within the formylperylene (FPe)-methanol (MeOH) systems facilitated by intermolecular hydrogen bonding interactions is theoretically studied in both the ground state S0 and the first singlet excited state S1. The geometric structures, electronic spectra and the infrared spectra of the FPe monomer as well as the various hydrogen-bonded FPe-MeOH complexes in both states were calculated with the density functional theory (DFT) method and time-dependent density functional theory (TD-DFT) methods, respectively. It is demonstrated that the total effect of the intermolecular hydrogen bonding between FPe and the MeOH molecules becomes strengthened in the ground state as the number of the MeOH molecules hydrogen-bonded to the FPe molecule increases from zero to three, which induces large increases in the dipole moment as well as systemic redshifts of the absorption spectra of FPe. Furthermore, upon photoexcitation of the FPe molecule, the intermolecular hydrogen bonds formed in the various hydrogen-bonded FPe-MeOH complexes are further strengthened which leads to even larger dipole moments as well as obvious redshifts of the fluorescence spectra. The calculated electronic spectra of the various hydrogen-bonded FPe-MeOH complexes are in agreement with the steady-state absorption and fluorescence spectra of FPe observed in the binary mixed solvents with different MeOH concentration. The intermolecular hydrogen bonding strengthening in both the ground and excited states are further confirmed by the infrared spectra shifts. Moreover, the vitally important role played by the intermolecular hydrogen bonding interaction and its strengthening upon electronic excitation in the CT process is discussed.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2013; 117C:379-388. · 1.98 Impact Factor
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    ABSTRACT: The entire 12 Λ–S states of CCl+ correlated to ground state atom C+ and Cl are calculated at scalar relativistic MRCI+Q/AV5Z level of theory. Spin–orbit interaction causes the 12 Λ–S states to split into 23 Ω states. The potential energy curves (PECs) of Λ–S and Ω states are depicted with the aid of the avoided crossing rule between the same symmetry. This is the first time that spin–orbit coupling (SOC) calculation has been carried out on CCl+. The spin–orbit coupling effect, leading to many avoided crossings, is found to be substantial for CCl+. The spectroscopic constants of the bound Λ–S and Ω states are determined, where a better agreement with experimental data is found. The predissociations for a3Π and A1Π induced by SOC are analyzed. Moreover, the transition properties, including transition dipole moments and Franck–Condon factors, are derived. Subsequently, the radiative lifetimes of transition a3Π0+–X1Σ+0+ and a3Π1–X1Σ+0+ are calculated.
    Journal of Quantitative Spectroscopy and Radiative Transfer 04/2013; 119:23–31. · 2.38 Impact Factor
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    ABSTRACT: Quasi-classical trajectory calculations have been carried out for the reaction H+HS by using the newest triplet 3A" potential energy surface (PES). The effects of the collision energy and reagent initial rotational excitation are studied. The cross sections and thermal rate constants for the title reaction are calculated. The results indicate that the integral cross sections (ICSs) are sensitive to the collision energy and almost independent to the initial rotational states. The ro-vibrational distributions for the product at different collision energies are presented. The investigations on the vector correlations are also performed. It is found that the collision energies play a postive role on the forward scatter of the product molecules. There is a negative influence on both the alignment and orientation of the product angular momentum for low collision energy at low energy region. Whereas the influence of collision energy is not obvious at high energy region.
    Bulletin- Korean Chemical Society 01/2013; 34(11). · 0.98 Impact Factor
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    ABSTRACT: A new experimental apparatus has been developed, which can be used to accurately measure the spectral emissivity of opaque materials using a reflector as the dummy light source. The experimental apparatus is mainly composed of the optical detection system, heating system, temperature-controlling system, angle-adjusting system and signal-controlling and data-computing system. The optical system works at 1.5 μm and the bandwidth is 20 nm. The sample can be heated up to about 1200 K by the sample heater. The temperature of sample surface is measured by the two highly accurate platinum–rhodium thermocouples and is controlled by means of a microcomputer-controlled proportional–integral–derivative device. The temperature-controlling error is within 2 K over the experimental range from 700 to 1200 K. A reflector is used as the dummy light source to realize the single-wavelength measurements of spectral emissivity. The present apparatus can be used to perform the measurements of spectral emissivity as a function of temperatures and emission angles. The spectral emissivity of several opaque materials has been measured by the apparatus. As an example, the spectral emissivity results of polished aluminum sheet over the temperature range from 788 to 1028 K have been reported here. The analytic dependence between the spectral emissivity and temperature has been determined. The temperature determined by the two thermocouples is employed to assess the accuracy of spectral emissivity measured here. The comparison between the temperatures measured by the thermocouples and those calculated by the emissivity obtained here demonstrates that the results measured by the apparatus achieve much high accuracy and that the proposed measurement technique is reliable.
    International Journal of Heat and Mass Transfer 06/2012; 55(s 13–14):3344–3348. · 2.32 Impact Factor
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    ABSTRACT: The potential energy curves (PECs) of the X(3)Π, a(1)Σ(+), b(1)Π, A(3)Σ(+), B(3)Σ(-), c(1)Δ, D(3)Π, 1(5)Π, 3(1)Σ(+), 3(3)Π, 2(1)Π, 2(3)Σ(+), 1(3)Δ, 1(5)Σ(+), 4(3)Π, 2(3)Σ(-) and 1(5)Σ(-) electronic states of the BN molecule are calculated using an ab initio quantum chemical method. The PEC calculations have been made for internuclear separations from 0.06 to 1.20 nm using the complete active space self-consistent field (CASSCF) method, which is followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV5Z basis set. To improve the quality of PECs, core-valence correlation and relativistic corrections are included. Relativistic correction calculations are carried out using the third-order Douglas-Kroll Hamiltonian (DKH3) approximation. Core-valence correlation corrections are included using a cc-pCVQZ basis set. Relativistic corrections are calculated at the level of a cc-pVQZ basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). These PECs are extrapolated to the complete basis set limit by the total-energy extrapolation scheme. The spectroscopic parameters are determined by fitting the vibrational levels, which are calculated in a direct forward manner from the analytic potential by solving the ro-vibrational Schrödinger equation using Numerov's method. The spectroscopic results have been compared in detail with those reported in the literature. Excellent agreement has been found between the present spectroscopic results and the experimental ones. Using the Breit-Pauli operator, the spin-orbit coupling effect on the spectroscopic parameters is included in the X(3)Π and D(3)Π electronic states. The vibrational level, inertial rotation and centrifugal distortion constants are calculated for each vibrational state of each electronic state. And those of the first 20 vibrational states of each electronic state are reported when the rotational quantum number equals zero. Comparison with the measurements shows that the present results are accurate. The spectroscopic parameters of the c(1)Δ, 1(5)Π, 3(1)Σ(+), 3(3)Π, 2(1)Π, 2(3)Σ(+), 1(3)Δ, 1(5)Σ(+), 4(3)Π and 1(5)Σ(-) electronic states and the vibrational manifolds of all the electronic states obtained here are expected to be reliable predicted results.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 93:367-78. · 1.98 Impact Factor
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    ABSTRACT: The time-dependent density functional theory (TDDFT) method has been applied to investigate the excited states of 2′-deoxyguanosine (2′-dG) and its monohydrated complex (2′-dG-W1). The intramolecular hydrogen bonding N3⋯H2–O2 of the keto conformer is weakened in the S1 state, while that of the enol conformers is strengthened. The two intermolecular hydrogen bondings of 2′-dG-W1 are weakened in the S1 state, while N3⋯H2–O2 gets more strengthened. Moreover, the fluorescence of 2′-dG-W1 is shifted to higher frequencies compared with that of monomer 2′-deoxyguanosine. Therefore, it is concluded that the weakening of intermolecular hydrogen bonding in the S1 state induces fluorescence strengthening of 2′-deoxyguanosine.
    Chemical Physics Letters 03/2012; 528:53–58. · 2.15 Impact Factor
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    ABSTRACT: The potential energy curves (PECs) of nine low-lying electronic states (X2Σ+, A2Π, B2Σ+, C2Δ, D2Π, a4Σ+, 14Δ, b4Π and 14Σ−) of the CO+ cation have been studied using an ab initio quantum chemical method. The calculations have been performed employing the complete active space self-consistent field (CASSCF) method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV5Z basis set. To improve the quality of the PECs, core–valence correlation and relativistic corrections are included. Relativistic corrections are included using the third-order Douglas–Kroll Hamiltonian approximation. Core–valence correlation corrections are included using a cc-pCVQZ basis set. Relativistic corrections are included at the level of the cc-pV5Z basis set. In order to obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). Analyses show that the effects on the spectroscopic parameters by the core–valence correlation correction, relativistic correction and Davidson modification are obvious, whereas the effect on the spectroscopic parameters by the nonadiabatic correction can be neglected. For the X2Σ+, A2Π, B2Σ+ and C2Δ electronic states, six main isotopologues (12C16O+, 12C17O+, 12C18O+, 13C16O+, 13C17O+ and 13C18O+) have been studied, since their experimental spectroscopic parameters and molecular constants are relatively abundant. For the D2Π, a4Σ+, 14Δ, 14Σ− and b4Π electronic states, just the most naturally abundant isotopologue, 12C16O+, is investigated. These results have been compared in detail with those reported in the literature. Excellent agreement has been found between the present results and the experimentally determined ones. The molecular constants of the C2Δ and the spectroscopic parameters of the D2Π, a4Σ+, 14Δ, 14Σ− and b4Π electronic states determined by the MRCI+Q/aug-cc-pV5Z+CV+DK calculations are expected to be reliable predicted results.
    Ecological Modelling - ECOL MODEL. 12/2011;
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    ABSTRACT: Based on the definition of spectral emissivity, an experimental apparatus for normal spectral emissivity measurement at different temperatures has been developed. The sample and blackbody are heated by the same heating system, which permits to measure spectral emissivity up to 1273K. The temperatures of the sample and blackbody are measured and controlled by an infrared radiation thermometer and PID controller. The signal detection is carried out by a silicon photo detector at 1.5 μm. The experimental results focus on the capability of the apparatus to perform emissivity measurements as a function of temperature at a fixed wavelength. Using this apparatus, the spectral emissivity of SUS304 is first measured at different temperatures. In order to validate the measurement capability of the apparatus for different sample, three kinds of steel samples which have different percentages of constituents were measured. The measurement uncertainty of the experimental apparatus is analyzed. The overall uncertainty of the apparatus estimated is about 5%.
    Proc SPIE 11/2011;
  • Kedong Wang, Tongjun Miao, Yufang Liu
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    ABSTRACT: All the possible rotamers of N,N-dimethylaminoethanol (DMAE) were fully optimized at the ab initio level using hybrid density functional B3LYP/aug-cc-pVDZ method. Twelve local minima for DMAE were found and their geometric parameters, dipole moments, intramolecular hydrogen bonds (HB) and relative energies of all conformers were determined. Their relative energies calculated at MP3 and MP4 (SDTQ) levels of theory further confirm that the gauche′-Gauche-gauche′ (g′Gg′) conformer having the intramolecular HB OH⋯N is the most stable. The vertical ionization energies of the conformers calculated with ab initio electron propagator theory in the P3/aug-cc-pVTZ approximation are in agreement with the experimental data from photoelectron spectroscopy. Combined with statistical mechanics principles, conformational distributions at various temperatures are computed and the temperature dependence of photoelectron spectra (PES) is interpreted. The intramolecular HB OH⋯N influences on the molecular electronic structures in the conformer g′Gg′ was exhibited by Natural bond orbital (NBO) analyzes.
    Computational and Theoretical Chemistry. 10/2011; 972(s 1–3).
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    ABSTRACT: The intermolecular hydrogen bond N-H···S between indole and dimethyl sulfide is theoretically investigated. The formation of N-H···S hydrogen bonds between indole and dimethyl sulfide in ground and excited states is confirmed by the analysis of geometric structure, Mulliken charge, and infrared spectra. The result shows that the S(1) state of hydrogen bonded indole-Me(2)S is mainly a charger transfer state, while the S(2) state is a local excited state and also the state corresponding to the experiment. More importantly, it is demonstrated that the intermolecular hydrogen bond N-H···S of indole-Me(2)S is strengthened in the S(1) and S(2) states compared to that in ground state. Moreover, the strengthening of intermolecular N-H···S hydrogen bond in excited state induces the fluorescence emission peak of indole shifts to the red. These findings may provide insights for further study of N-H···S hydrogen bonds existing in many biomolecular systems.
    Physical Chemistry Chemical Physics 09/2011; 13(33):15299-304. · 3.83 Impact Factor
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    ABSTRACT: The potential energy curves (PECs) of eight low-lying electronic states (X1Σ+, a3Σ+, b3Π, d3Δ, C1Σ−, e3Σ−, D1Δ and A1Π) of SiS molecule were investigated with the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach with the correlation-consistent basis sets, aug-cc-pV5Z and aug-cc-pV6Z. Effect on the PECs by the relativistic correction is taken into account. The way to consider the relativistic correction is to use the second-order Douglas–Kroll Hamiltonian (DKH2) approximation. And the relativistic correction is made at the level of cc-pV5Z basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). The PECs are extrapolated to the complete basis set (CBS) limit by the two-point total-energy extrapolation scheme. With these PECs, the spectroscopic parameters (Te, De, Re, ωe, ωexe, ωeуe, Be and αe) are determined and compared with those reported in the literature. With the PECs obtained by the MRCI+Q/DK+56 calculations, the vibrational levels and inertial rotation and centrifugal distortion constants of the first 30 vibrational states are calculated for each electronic state involved here when the rotational quantum number J is equal to zero. Comparison with the measurements shows that the present total-energy extrapolation could improve the quality of spectroscopic parameters. On the whole, as expected, the spectroscopic parameters and molecular constants closest to the experimental data are determined by the MRCI+Q/DK+56 calculations for these electronic states.
    Computational and Theoretical Chemistry. 08/2011; 969(s 1–3):17–26.
  • Computational and Theoretical Chemistry. 06/2011; 966(s 1–3):44–53.
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    ABSTRACT: Quasi-classical trajectory (QCT) method is used to calculate the stereodynamics of the reactions H + LiH (v = 0, j = 0) → H2 + Li and its isotopic variants based on the ground electronic state potential energy surface (PES) reported by Prudente et al. [14]. The reactive probabilities of the title reactions are computed. We also observed the changes of vector correlations and four generalized polarization-dependent differential cross-sections (PDDCSs) at different collision energies, and we compared the stereodynamics among different isotopic variants of the title reactions. The product polarization distribution of the title reactions exhibits distinct difference which may arise from different mass combinations or kinetic energies.
    Computational and Theoretical Chemistry. 04/2011; 965(1):107–113.

Publication Stats

133 Citations
65.54 Total Impact Points

Institutions

  • 2014
    • Hu Nan Normal University
      Ch’ang-sha-shih, Hunan, China
  • 1998–2014
    • Henan Normal University
      Henan’an, Guangdong, China
  • 2013
    • North China University of Water Conservancy and Electric Power
      Cheng, Henan Sheng, China
  • 2008
    • Xinyang Normal University
      Sinyang, Henan Sheng, China