Highly Active Pd-PEPPSI Complexes for Suzuki-Miyaura Cross-coupling of Aryl Chlorides: an Investigation on the Effect of Electronic Properties

Three new Pd-pyridine enhanced precatalyst preparation stabilization and initiation(PEPPSI) complexes with halogen groups on the N-heterocyclic carbene and pyridine were prepared. Their structures have been clearly characterized by nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. The effects of the electronic properties of halogen groups on the catalytic activity in the Suzuki-Miyaura cross-coupling of aryl chlorides were investigated. These Pd-PEPPSI complexes could catalyze the cross-coupling reaction efficiently with a low catalyst loading(0.05%, molar ratio) at room temperature and the products were obtained in high yields.     

An Air-Stable,Neutral Phenothiazinyl Radical with Substantial Radical Stabilization Energy

The vital effect of radical states on the pharmacological activity of phenothiazine-based drugs has long been speculated. Whereas cationic radicals of N-substituted phenothiazines show high stability, the respective neutral radicals of N-unsubstituted phenothiazines have never been isolated. Herein, the 1,9-diamino-3,7-di-tert-butyl-N¹,N⁹-bis(2,6-diisopropylphenyl)-10H-phenothiazin-10-yl radical (SQH₂^.) is described as the first air-stable, neutral phenothiazinyl free radical. The crystalline dark-blue species is characterized by means of EPR and UV/Vis/near-IR spectroscopy, as well as cyclic voltammetry, spectro-electrochemical analysis, single-crystal XRD, and computational studies. The SQH₂^. radical stands out from other aminyl radicals by an impressive radical stabilization energy and its parent amine has one of the weakest N−H bond dissociation energies ever determined. In addition to serving as open-shell reference in medicinal chemistry, its tridentate binding pocket or hydrogen-bond-donor ability might enable manifold uses as a redox-active ligand or proton-coupled electron-transfer reagent.     

Operating range of magnetic stabilization flow regime for magnetized fluidized bed with Geldart-B magnetizable and nonmagnetizable particles

The magnetic stabilization flow regime could also be created for Geldart-B nonmagnetizable particles provided some magnetizable particles are introduced and the magnetic field is applied. This study aimed to explore the size (d_pM) and density (Ͽ_pM) effects of magnetizable particles on its operating range. The upper limit (U_mbH) could not be determined from the οP_b⿿U_g⿿ curve but could from analyzing the variation of οP_b-fluctuation with increasing U_g. Due to the variation of U_mfH (lower limit) with d_pM and Ͽ_pM, both U_mbH⿿U_mfH and (U_mbH⿿U_mfH)/U_mfH were used to quantify the operating range of magnetic stabilization. U_mbH⿿U_mfH varied hardly with d_pM but increased significantly with decreasing Ͽ_pM. (U_mbH⿿U_mfH)/U_mfH increased as d_pM or Ͽ_pM decreased. It was more difficult for the nonmagnetizable particles to escape from the network formed by the smaller/lighter magnetizable particles. For the same magnitude of change, d_pM had a stronger effect than Ͽ_pM on (U_mbH⿿U_mfH)/U_mfH. Neither U_mbH⿿U_mfH nor (U_mbH⿿U_mfH)/U_mfH varied monotonously with the minimum fluidization velocity of the magnetizable particles, indicating that no straightforward criterion for matching the magnetizable particles to the given nonmagnetizable particles could be established based on their minimum fluidization velocities to maximize the operating range of magnetic stabilization.     

Photolytic transformation of aryl benzobisoxazole and aryl benzobisthiazole compounds into carbon dioxide

Solid‐state aryl benzobisoxazole and aryl benzobisthiazole compounds photolyzed in the presence of O₂ undergo cleavage to produce benzobisoxazoles (or benzobisthiazoles), benzonitriles, and benzamides. A very high percentage of the carbon atoms in one of the two segments from chain cleavage are converted to CO₂. This very unusual observation has been carefully confirmed by gas chromatography/mass spectroscopy analysis of the gaseous components in the photolysis vessel before and after photolysis, labeling experiments, and the correlation of the mass reduction in photolyzed polymers and the amount of CO₂ that evolves. The rate of CO₂ generation is used to compare the relative photostability of aryl benzobisoxazole and aryl benzobisthiazole model compounds, films, and fibers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1868–1877, 2007     

Decay rates of the plate equations

We consider the Kirchhoff plate equation and the Bernoulli–Euler plate equation. The energy decay rate in both cases is investigated. Moreover, when we do not have exponential stability in the energy space, we give explicit logarithmic decay estimates valid for regular initial data. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

一义线性系统的分散控制的再研究

本文利用混合型输出反馈控制研究了广义线性系统的分散控制，给出了一个广义线性系统在混合型输出反馈下存在脉冲固定模的充分条件。     

Thermo‐ and photo‐oxidative stability and improved processability of polyamide stabilized with a new functional additive

During processing polyamides can undergo thermo‐mechanical degradation due to the mechanical stress and to the high temperature applied to the melt. Degradation can occur also during the polyamides lifetime due to many driving forces, like temperature, ultraviolet radiations, etc. The mechanisms of degradation are not well understood and the stabilization with usual stabilizers, like phenol antioxidants, is not so efficient as for other classes of polymers. The aim of this work is the study of the effects of the addition of a new multifunctional additive on the processing and on the thermo‐ and photo‐stabilization of polyamide‐6. This additive is able to prevent the thermo‐mechanical degradation and also to enlarge the molecular weight distribution improving the processability of this polymer in operations where the elongational flow is involved. Moreover, the presence of this additive extends significantly the lifetime of the polyamide when subjected to thermo‐ and photo‐oxidative stress. Copyright © 2005 John Wiley & Sons, Ltd.     

Decentralized adaptive generalized predictive control for structural vibration

A decentralized generalized predictive control (GPC) algorithm is developed for strongly coupled multi-input multi-output systems with parallel computation. The algorithm is applied to adaptive control of structural vibration. The key steps in this algorithm are to group the actuators and the sensors and then to pair these groups into subsystems. It is important that the on-line identification and the control law design can be a parallel process for all these subsystems. It avoids the high computation cost in ordinary predictive control,and is of great advantage especially for large-scale systems.     

和谐与稳定的哲学分析

在现阶段，要构建社会主义和谐社会，就要认识并处理好和谐与稳定两者之间的关系。这是一种辩证统一关系，即和谐是稳定的前提，稳定是和谐的保障，而和谐又是稳定的更高阶段。同时，和谐与稳定统一的基础是发展，关键是协调。目标就是社会的全面进步与人的全面发展。     

Bio-energy in s-Helix Protein Molecules with Three Properties of Soliton-Transported Channels

We study numerically the propagating properties of soliton-transported bio-energy excited in the a-helix protein molecules with three channels in the cases of the short-time and long-time motions and its features of collision at temperature T = 0 and biological temperature T = 300 K by the dynamic equations in the improved Davydov theory and fourth-order Runge-Kutta method, respectively. From these simulation experiments we see that the new solitons in the improved model can move without dispersion at a constant speed retaining its shape and energy in the cases of motion of both short-time or T = 0 and long time or T = 300 K and can go through each other without scattering in their collisions. In these cases its lifetime is, at least, 120 ps at 300 K, in which the soliton can travel over about 700 amino acid residues. This result is consistent with analytic result obtained by quantum perturbed theory in this model. In the meanwhile, the influences of structure disorder of a-helix protein molecules, including the inhomogeneous distribution of amino acids with different masses and fluctuations of spring constant, dipole-dipole interaction, exciton-phonon coupling constant and diagonal disorder, on the solitons are also studied by the fourth-order Runge-Kutta method. The results show that the soliton still is very robust against the structure disorders and thermal perturbation of proteins at biological temperature 300 K. Therefore we can conclude that the new soliton in the a-helix protein molecules with three channels is a possible carrier of bio-energy transport and the improved model is possibly a candidate for the mechanism of this transport.