Stepsize Range and Optimal Value for Taylor-Zhang Discretization Formula Applied to Zeroing Neurodynamics Illustrated via Future Equality-Constrained Quadratic Programming.

In this brief, future equality-constrained quadratic programming (FECQP) is studied. Via a zeroing neurodynamics method, a continuous-time zeroing neurodynamics (CTZN) model is presented. By using Taylor-Zhang discretization formula to discretize the CTZN model, a Taylor-Zhang discrete-time zeroing neurodynamics (TZ-DTZN) model is presented to perform FECQP. Furthermore, we focus on the critical parameter of the TZ-DTZN model, i.e., stepsize. By theoretical analyses, we obtain an effective range of the stepsize, which guarantees the stability of the TZ-DTZN model. In addition, we further discuss the optimal value of the stepsize, which makes the TZ-DTZN model possess the optimal stability (i.e., the best stability with the fastest convergence). Finally, numerical experiments and application experiments for motion generation of a robot manipulator are conducted to verify the high precision of the TZ-DTZN model and the effective range and optimal value of the stepsize for FECQP.

Docking and molecular dynamics studies on triclosan derivatives binding to FabI.

FabI, enoyl-ACP reductase (ENR), is the rate-limiting enzyme in the last step for fatty acids biosynthesis in many bacteria. Triclosan (TCL) is a commercial bactericide, and as a FabI inhibitor, it can depress the substrate (trans-2-enoyl-ACP) binding with FabI to hinder the fatty acid synthesis. The structure-activity relationship between TCL derivatives and FabI protein has already been acknowledged, however, their combination at the molecular level has never been investigated. This paper uses the computer-aided approaches, such as molecular docking, molecular dynamics simulation, and binding free energy calculation based on the molecular mechanics/Poisson-Bolzmann surface area (MM/PBSA) method to illustrate the interaction rules of TCL derivatives with FabI and guide the development of new derivatives. The consistent data of the experiment and corresponding activity demonstrates that electron-withdrawing groups on side chain are better than electron-donating groups. 2-Hydroxyl group on A ring, promoting the formation of hydrogen bond, is vital for bactericidal effect; and the substituents at 4-position of A ring, 2'-position and 4'-position of B ring benefit antibacterial activity due to forming a hydrogen bond or stabilizing the conformation of active pocket residues of receptor. While the substituents at 3'-position and 5'-position of B ring destroy the π-π stacking interaction of A ring and NAD+ which depresses the antibacterial activity. This study provides a new sight for designing novel TCL derivatives with superior antibacterial activity.