Li Ze-Sheng

Inhibition Mechanism of Cholinesterases by Carbamate: A Theoretical Study

Abstract The density functional theory at the B3LYP/6-311 G(d, p) level was applied to exploring the inhibition mechanism of cholinesterases by carbamate. The results indicate that the inhibition reactions with or without the catalytic effect of the catalytic triad in cholinesterases underwent a two-step addition-elimination mechanism, which is in good agreement with the proposed mechanism. The solvent has a strong effect on the inhibition reactions and the reaction with the catalytic triad in the solvent phase is close to the real reaction under biological condition.

On the polycondensation reaction of Aa-BbCc type

SummaryThe curing theory for polycondensation reaction of Aa-BbCc type is investigated in detail to give gelation condition explicitly. Furthermore, a recursion formula for evaluating the polymer moments is obtained. This formula is suitable for both pre-gel and post-gel.

Flory-Stockmayer distribution and scaling study

Abstract By means of the Flory-Stockmayer distribution, the critical behavior of the kth radius near the gel point is investigated. As a direct result, a scaling law associated with the kth radius is deduced.

Molecular Dynamics Simulation Studies on the Cooling Process of Polyvinyl Chloride

By means of molecular dynamics simulation, the transition of the conformations of polyvinyl chloride during a cooling process from 600 to 300 K was studied. The results show that the amorphous polyvinyl chloride chain experiences the melting state, elastic state and glass state and the conformations can be characterized by the increases of the trans-state of C C C C and the near gauche-state of C C C Cl with the decrease of temperature. It is found that the transition of the conformations is driven mainly by the Coulomb interaction between chain segments.

Computer simulations on the gas-liquid phase diagram of Stockmayer fluids

Particle exchange molecular dynamics (PEMD) simulation technique is proposed to study the gas-liquid phase diagram of fluids. In the simulations, the fluid particles can be transferred between the two coupled boxes, which possess constant total number of particles and volume. The particle transfer is controlled by the difference of chemical potential in the respective simulation box. After equilibrium the two boxes have the same pressure, temperature and chemical potential. The method is further used to study the gas-liquid phase diagram of Stockmayer fluid. Increasing the dipole strength will enhance the critical temperature. The predicted critical points are in agreement with those from Gibbs ensemble Monte Carlo simulations, while the small systematic difference is attributed to the system size effects and the thermostat methods.