Preparation and characterization of optically active polystyrene via a chiral nitroxide‐mediated polymerization

2,2,6,6‐Tetramethyl‐4‐[d‐(+)‐10‐camphorsulfonyl]‐1‐piperidinyloxy was synthesized and used as a chiral nitroxide for the bulk polymerizations of styrene initiated with benzoyl peroxide (BPO), tetraethylthiuram disulfide (TETD), and thermal initiation. The results showed that the polymerizations proceeded in a controlled/living way; that is, the kinetics presented approximately first‐order plots, and the number‐average molecular weights of the polymers with narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight) increased with the monomer conversion linearly. The molecular weight distributions in the case of thermal initiation were narrower than those in the case of BPO and TETD, whereas the polymerization rate with BPO or TETD as an initiator was obviously faster than that with thermal initiation. In addition, successful chain‐extension reactions were carried out, and the structures of the obtained polymers were characterized by gel permeation chromatography and ¹H NMR. The specific rotations of the polymers were also measured by polarimetric analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1522–1528, 2006     

One-dimensional stochastic Burgers equation driven by Lévy processes

In this paper, we proved the global existence and uniqueness of the strong, weak and mild solutions for one-dimensional Burgers equation perturbed by a Poisson form process, a Poisson form and Q-Wiener process with the Dirichlet bounded condition. We also proved the existence of the invariant measure of these models.     

Copper diffusion in Ti-Si-N layers formed by inductively coupled plasma implantation

Ternary Ti-Si-N refractory barrier films of 15 nm thick was prepared by low frequency, high density, inductively coupled plasma implantation of N into Ti_xSi_y substrate. This leads to the formation of Ti-N and Si-N compounds in the ternary film. Diffusion of copper in the barrier layer after annealing treatment at various temperatures was investigated using time-of-flight secondary ion mass spectrometer (ToF-SIMS) depth profiling, X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and sheet resistance measurement. The current study found that barrier failure did not occur until 650 °C annealing for 30 min. The failure occurs by the diffusion of copper into the Ti-Si-N film to form Cu-Ti and Cu-N compounds. FESEM surface morphology and EDX show that copper compounds were formed on the ridge areas of the Ti-Si-N film. The sheet resistance verifies the diffusion of Cu into the Ti-Si-N film; there is a sudden drop in the resistance with Cu compound formation. This finding provides a simple and effective method of monitoring Cu diffusion in TiN-based diffusion barriers.     

AN IMPROVED SEARCH-EXTENTION METHOD FOR SOLVING SEMILINEAR PDES

This article will combine the finite element method, the interpolated coefftcient finite element method, the eigenfunction expansion method, and the search-extension method to obtain the multiple solutions for semilinear elliptic equations. This strategy not only grently reduces the expensive computation, but also is successfully implemented to obtain multiple solutions for a class of semilinear elliptic boundary value problems with non-odd nonlinearity on some convex or nonconvex domains. Numerical solutions illustrated by their graphics for visualization will show the efficiency of the approach.     

Synthesis of double silylene-bridged binuclear titanium complexes and their use as catalysts for ethylene polymerization

Five new double silylene-bridged binuclear titanium complexes were synthesized by the reaction of RCpTiCl₃ and Li₂[μ,μ-(SiMe₂)₂ (C₅H₃)₂] in toluene. They were all well characterized. These complexes activated with methylaluminoxane (MAO) are highly active catalysts (2.33 × 10⁵ g PE/mol Cat h) for the polymerization of ethylene even at low Al/Ti (Al/Ti = 300). The molecular weight distribution of the polymer indicates broad or bimodal (MWD = 26.76) distribution.     

半导体反型层中的电子关联和多体波函数

本文运用CBF(correlation basis function) 理论, 由电子间的有效势V_eff_(R) 和电子气的集体振荡行为, 给出准二维电子体系— 半导体反型层中的电子的关联因予U (R), 得到该体系的对关联函数、关联能和多体波函数. 关键词：     

合肥同步辐射软X射线显微术研究

合肥国家同步辐射实验室首期建设的光束线之一用于软Ｘ射线显微成像研究。实验站现已装置初型的扫描透射Ｘ射线显微镜，并正在进行亲一代的扫描显微建设，同时还使同步辐射光进行接触软Ｘ射线呈微成像研究，并对选取的一些生物样品进行了成像试验。本文介绍了合肥同步辐射光源上软Ｘ射线显微术实验线站的建设及完成的一些实验结果。     

两种群竞争模型的奇摄动群

本文应用多重尺度法构造出非线性微分方程组的解的渐近展开式。并用微分不等式的技巧，证明原问题的解的存在性，且给出解的一致有效渐近估计．     

具有唯一4度最大度点的图的全色数

一个图Ｇ的全色数χ_T（Ｇ）是使得Ｖ（Ｇ）∪Ｅ（Ｇ）中相邻或相关联元素均染不同颜色的最少颜色数．文中证明了，若图Ｇ只有唯一的一个４度最大度点，则χ_T（Ｇ）＝Δ（Ｇ）＋１．     

不同波长激光辐照对痢疾杆菌生物学效应的影响

分别采用功率密度为1.7W/cm²、照射剂量为2000J/cm²的Ar⁺激光与LD激光辐照高耐药性的志贺氏福氏痢疾杆菌,波长较短的Ar⁺激光(488nm)所引起细菌的致死率与药敏实变率明显高于波长较长的LD激光(808nm),即波长较短的Ar⁺激光的辐照导致细菌耐药性显著降低.