Changchun, China
Changchun, China

Changchun Normal University is a university in Changchun, Jilin, People's Republic of China. Wikipedia.

Time filter

Source Type

Hu L.,Changchun Normal University | Hu L.,Lund University | Ryde U.,Lund University
Journal of Chemical Theory and Computation | Year: 2011

We have critically examined and compared various ways to obtain standard harmonic molecular mechanics (MM) force-field parameters for metal sites in proteins, using the 12 most common Zn2+ sites as test cases. We show that the parametrization of metal sites is hard to treat with automatic methods. The choice of method is a compromise between speed and accuracy and therefore depends on the intended use of the parameters. If the metal site is not of central interest in the investigation, for example, a structural metal far from the active site, a simple and fast parametrization is normally enough, using either a nonbonded model with restraints or a bonded parametrization based on the method of Seminario. On the other hand, if the metal site is of central interest in the investigation, a more accurate method is needed to give quantitative results, for example, the method by Norrby and Liljefors. The former methods are semiautomatic and can be performed in seconds, once a quantum mechanical (QM) geometry optimization and frequency calculation has been performed, whereas the latter method typically takes several days and requires significant human intervention. All approaches require a careful selection of the atom types used. For a nonbonded model, standard atom types can be used, whereas for a bonded model, it is normally wise to use special atom types for each metal ligand. For accurate results, new atom types for all atoms in the metal site can be used. Atomic charges should also be considered. Typically, QM restrained electrostatic potential charges are accurate and easy to obtain once the QM calculation is performed, and they allow for charge transfer within the complex. For negatively charged complexes, it should be checked that hydrogen atoms of the ligands get proper charges. Finally, water ligands pose severe problems for bonded models in force fields that ignore nonbonded interactions for atoms separated by two bonds. Complexes with a single water ligand can normally be accurately treated with a bonded potential, once it is ensured that the water H atoms have nonzero Lennard-Jones parameters. However, for metal sites with several water molecules, a nonbonded model with restraints (taken from the QM calculations) is more stable. © 2011 American Chemical Society.

Lu Y.-F.,Changchun Normal University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

In the present study, corn canopy is the objective. Firstly the polarization of corn canopy was analyzed based on polarization reflection mechanism; then, the polarization of canopy was measured in different growth period at nadir before heading. The result proved the theoretical derivation that the light reflected from corn canopy is polarized, and found that in the total reflection the polarization light accounts for up to 10%. This shows that polarization measurement provides auxiliary information for remote sensing, but also illustrates that the use of the polarization information retrieval of atmospheric parameters should be considered when the surface polarization affects on it.

Chen J.,Jilin University | Chen J.,Changchun Normal University | Wang X.,Jilin University | Cui X.,Jilin University | And 2 more authors.
Chemical Communications | Year: 2014

An amorphous metal-free N-doped carbon film prepared by sputtering and annealing exhibits comparable electrocatalytic activity and superior stability and methanol tolerance to the commercial Pt/C catalyst via a four-electron pathway for oxygen reduction reaction (ORR). Pyridinic nitrogen in films plays a key role in electrocatalytic activity for ORR. This journal is © The Royal Society of Chemistry 2014.

Wang C.,Changchun Normal University
Advanced Materials Research | Year: 2012

Topology control is an efficient approach which can reduce energy consumption for wireless sensor networks, and the current algorithms mostly focus on reducing the nodes' energy consumption by power adjusting, but pay little attention to balance energy consumption of the whole network, which results in premature death of many nodes. Thus, a distributed topology control algorithm based on path-loss and residual energy (PRTC) is designed in this paper. This algorithm not only maintains the least loss links between nodes but also balances the energy consumption of the network. The simulation results show that the topology constructed by PRTC can preserve network connectivity as well as extend the lifetime of the network and provide good performance of energy consumption. © (2012) Trans Tech Publications, Switzerland.

Liang S.,Changchun Normal University | Liang S.,Jilin University | Zhang J.,Nanjing Normal University
Nonlinear Analysis: Real World Applications | Year: 2014

In this paper, we consider the existence and multiplicity of solutions of Kirchhoff type problems with critical nonlinearity in R3:- ε2(a+b∫R3|u|2dx) Δu+V(x)u=K(x)|u|4u+h(x,u), (t,x) â̂̂R×R3. Under suitable assumptions, we prove that this has at least one solution and for any mâ̂̂N, it has at least m pairs of solutions. © 2013 Elsevier Ltd. All rights reserved.

Liang S.,Changchun Normal University | Zhang J.,Nanjing Normal University
Computers and Mathematics with Applications | Year: 2011

In this paper, we consider the following nonlinear fractional three-point boundary value problem D0+αu(t)+f(t,u(t))=0,0

Liang S.,Changchun Normal University | Zhang J.,Nanjing Normal University
Mathematical and Computer Modelling | Year: 2011

In this paper we consider the following m-point fractional boundary value problem on infinite interval D0+ αu(t) + a(t)f(t,u(t))=0,0

Chuhang W.,Changchun Normal University
Proceedings - 4th International Conference on Intelligent Computation Technology and Automation, ICICTA 2011 | Year: 2011

Wind energy is one of the important renewable energy sources which could reduce the emission of carbon dioxide in order to improve the current severe situation of environment. Therefore, more and more attentions are focused on wind power generation. However, almost all wind turbines work in harsh and unattended environment, then condition monitoring as well as fault diagnosis is crucial to keep the wind turbines running. In this paper, a remote monitoring and diagnosis system for wind turbines based on controller area network (CAN) is presented. The monitoring parameters and the system framework and design of CAN interface are described in detail. © 2011 IEEE.

Liang S.,Changchun Normal University | Zhang J.,Nanjing Normal University
Computers and Mathematics with Applications | Year: 2011

In this paper, we investigate the existence of three positive solutions for the following m-point fractional boundary value problem on an infinite interval D0+ αu(t)+a(t)f(u(t))=0,0

Hu L.,Lund University | Hu L.,Changchun Normal University | Soderhjelm P.,ETH Zurich | Ryde U.,Lund University
Journal of Chemical Theory and Computation | Year: 2011

We have studied the convergence of QM/MM calculations with respect to the size of the QM system. We study a proton transfer between a first-sphere cysteine ligand and a second-sphere histidine group in [Ni,Fe] hydrogenase and use a 446-atom model of the protein, treated purely with QM methods as a reference. We have tested 12 different ways to redistribute charges close to the junctions (to avoid overpolarization of the QM system), but once the junctions are moved away from the active site, there is little need to redistribute the charges. We have tested 13 different variants of QM/MM approaches, including two schemes to correct errors caused by the truncation of the QM system. However, we see little gain from such correction schemes; on the contrary, they are sensitive to the charge-redistribution scheme and may cause large errors if charges are close to the junctions. In fact, the best results were obtained with a mechanical embedding approach that does not employ any correction scheme and ignores polarization. It gives a mean unsigned error for 40 QM systems of different sizes of 7 kJ/mol with a maximum error of 28 kJ/mol. The errors can be significantly decreased if bonds between the QM and MM system (junctions) are moved one residue away from all active-site residues. Then, most QM/MM variants give mean unsigned errors of 5-9 kJ/mol, maximum errors of 16-35 kJ/mol, and only five to seven residues give an error of over 5 kJ/mol. In general, QM/MM calculations converge faster with system size than pure QM calculations. © 2011 American Chemical Society.

Loading Changchun Normal University collaborators
Loading Changchun Normal University collaborators