压水堆控制棒导向筒结构改进对落棒的影响

为改善横向水力载荷对控制棒导向筒的作用，对靠近上腔室出口管嘴附近的控制棒导向筒（对称的４组：０２－２６，０３－２５，１１－２９，１２－２８）加设了保护套．在秦山核电站压水堆上腔室１４的可视化模拟体中，以水为介质进行了实验研究，把结果与未加设保护套的实验结果作了分析比较，得到了对靠近上腔室出口管嘴附近的控制棒导向筒加设保护套有助于改善流场对控制棒导向筒的水力载荷作用和确保控制棒能按指令在导向筒中自由升降和快速下插的结论．     

Synthesis of cellulose carbamate by supercritical CO2-assisted impregnation: Structure and rheological properties

Cellulose carbamate, an environmentally friendly material presents an interesting alternative to petroleum-based polymers because of its renewable, biodegradable, biocompatible nature and its solubility in conventional solvents. In synthesis process of cellulose carbamate, urea was firstly impregnated into the cellulose pulp by supercritical CO₂(scCO₂), followed by the esterification of cellulose. The structure of cellulose carbamate was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The rheological properties of these cellulose carbamates in 9% sodium hydroxide solution were investigated, using a range of the nitrogen content, concentrations and shear rates.     

θ*r,s,t-图与唯一2-列表染色图的特征化

如果一个图G存在一个k-列表安排使得G具有一个唯一列表染色,则称 G是唯一列表可染色图,简称UkLC图．我们称图G具有M(k)性质当且仅当G不 是UkLC图．本文在借鉴θr,s,t-图概念的基础上引入θr,s,t-图的定义,并证明:除了 r=s=t=2以外,θr,s,t-图都是U2LC图．利用如上结果我们给出M．Mahdian and E．S．Mahmoodian对U2LC图所作特征化的一个简单证明．     

TiO2 粉末催化剂光催化降解室内 空气中有机污染物

本文制备了一系列 TiO2粉末催化剂, 用光催化法降解室内空气中各种微量有机污染物,最终降解率 接近 100%. 考察了晶型对光催化剂性能的影响, 结果表明,锐钛矿型 TiO2 的催化性能最好. 最后,分析了 TiO2 光催化反应机理.     

Momentum transfer from vacuum field to anisotropic electromagnetic media

It is demonstrated that many novel vacuum effects will be caused if an anisotropic electromagnetic environment, which can break the universal symmetry of vacuum, is achieved. It is thus possible for the momentum to be transferred from the vacuum zero-point field to the anisotropic electromagnetic media. In addition to the effect considered by Feigel more recently [A. Feigel, Phys. Rev. Lett. 92 (2004) 020404], there may exist another vacuum-fluctuation contribution to the momentum of a medium. Such an effect has a relativistic origin (resulting from the relativistic transformation of the optical constants), which, however, was not taken into account by Feigel.     

氯离子诱导的镍在硝酸溶液中的电流振荡

报道了氯了子诱导的镍在0．5mol.dm^-2硝酸溶液中活化－钝化过渡区电流振荡，在恒电位条件下，随着氯离子浓度的升高或者电极电位的降低，电流振荡由周期性振荡逐渐向非周期性振荡转变，根据实验结果，对该体系的电流振荡机理进行了讨论。     

The colloidal stability and core-shell structure of magnetite nanoparticles coated with alginate

The adsorption of alginate (Alg) onto the surface of in water dispersed Fe₃O₄ nanoparticles and zeta potential of alginate-coated Fe₃O₄ nanoparticles have been investigated to optimize the colloidal stability of Alg-coated Fe₃O₄ nanoparticles. The adsorption amount of Alg increased with the decrease of adsorption pH. The zeta potential of Fe₃O₄ nanoparticles shifted to a lower value after adsorption of Alg. The lower adsorption pH was the lower zeta potential of Fe₃O₄ nanoparticles became. The Alg-coated Fe₃O₄ nanoparticles were found to be stabilized by steric and electrostatic repulsions. Those prepared at pH 6 were not stable around pH 5, and those prepared at pH 4 became unstable at pH below 3.5. Alg of M_w 45 kDa was a little bit more adsorbed onto nanoparticles surface than that of M_w 24 kDa. An average Fe₃O₄ core size of 9.3 ± 1.7 nm was found by transmission electronic microscopy. An average hydrodynamic diameter of 30-150 nm was measured by photon correlation spectroscopy. However, an average core size of 10 nm and an average hydrodynamic diameter of 38 nm were estimated from the magnetization curve of the concentrated magnetic fluids (MFs). The maximum available saturation magnetization of MFs was about 3.5 kA/m.     

Study of HfSiO film prepared by electron beam evaporation for high-k gate dielectric applications

The purpose of this paper is to report some experimental results with HfSiO films formed on silicon substrates by electron beam evaporation (EB-PVD) and annealed at different temperatures. The images of atomic force microscope (AFM) indicated that HfSiO film annealed at 900 °C was still amorphous, with a surface roughness of 0.173 nm. X-ray photoelectron spectroscopy (XPS) analysis revealed that the chemical composition of the film was (HfO₂)₃(SiO₂) and Hf-Si-O bonds existed in the annealed film. Electrical measurements showed that the equivalent oxide thickness (EOT) was 4 nm, the dielectric constant was around 6, the breakdown voltage was 10 MV/cm, the fixed charge density was −1.2 × 10¹² cm⁻², and the leakage current was 0.4 μA/cm² at the gate bias of 2 V for 6 nm HfSiO film. The annealing after deposition effectively reduced trapping density and the leakage current, and eliminated hysteresis in the C-V curves. Annealing also induced SiO₂ growth at the interface.