强激光辐照下纳米铜动态拉伸型断裂的数值模拟

基于强激光辐照加载下纳米铜的层裂实验,采用含逾渗软化函数的损伤度函数模型对实验结果进行了数值模拟研究。强激光加载条件被简化为高斯分布脉冲压力施加在镍合金基体的前表面上。数值计算结果显示：损伤演化明显地改变了试样中波传播特性,无论是对微损伤还是完全层裂的试样,计算都较好地再现了实测自由面速度剖面,表明了含逾渗软化函数的损伤度函数模型在强激光加载条件下纳米铜层裂问题分析中具有较好适用性。     

Synthesis of Nano Silica Particles for Polishing Prepared by Sol–Gel Method

In order to produce an excellent abrasive, a fabrication method for cocoon shaped silica particles has been studied. The particles are prepared from TMOS, water, ammonia and methanol by a sol–gel method. The method is to add the methanol solution of TMOS at a constant supply rate to a mixture of water, ammonia and methanol. Effects of various reaction conditions such as temperatures, supply rates of TMOS, and amounts of TMOS are studied on the diameter and shape of the particles. The diameter and shape are resulted in depending strongly on temperatures. High temperature makes particles with the high aspect ratio and the small diameter. And the mechanism of forming the cocoon shaped particle is also discussed. It is concluded that the primary particles are generated at the beginning stage of reaction and two of them become the cocoon shaped particle. For the polishing efficiency, particles have high polishing efficiency with the diameter between 40 nm and 210 nm. As a result, best diameter of particles for abrasive is 40–100 nm with respect to polishing efficiency and surface finish.     

CeO2—TiO2复合纳米晶多孔膜的光电化学行为

用溶胶凝胶法制备了CeO2－TiO2复合纳米晶多孔膜电极，并用XRD及原子力显微镜（AFM）进行表征．通过光电化学研究，发现了CeO2-TiO2复合纳米晶电极光响应的p型和n型转换现象．结果表明，随着CeO2含量的不同及外电场的变化，CeO2－TiO2复合纳米晶电极可以呈现不同的光响应．     

复相陶瓷中颗粒桥联与相变协同增韧作用的力学分析

本文对复相陶瓷内延性金属颗粒和相变颗粒的协同增韧作用进行了力学分析，其中颗粒桥联效应还考虑了桥联颗粒与基体间工艺残余应力的影响，相变效应考虑了相变体膨胀和剪切塑性对增韧的共同贡献。数值计算结果与Ａｍａｚｉｇｏ－Ｂｕｄｉａｎｓｋｙ的结果及２Ｙ－ＴＺＰ／２０ＶＯＬ％Ｎｉ的实验结果作了比较。     

Surface charge density on spherical silica particles in aqueous alkali chloride solutions

The results of a systematic investigation on the influence of different alkali ion species on the surface charge density, ₀, of spherical silica particles (AEROSIL 300) in the pH range between 4 and 8 and with electrolyte concentrations from 0.005 M to 0.3 M are presented. The accuracy of the data may be described by a residual deviation,s( ₀ ^m ), including at least four single measurements:s( ₀ ^m )>0.2C/cm². The alkali sequence found for the spherical particles is in agreement with data for porous silica published by other authors.     

高效液相色谱法测定大气颗粒物中的杂环胺

建立了大气颗粒物中杂环胺的高效液相色谱检测方法.采用ODS C18色谱柱(250 mm×4.6 mm, 5 μm),乙腈-0.01 mol/L三乙胺缓冲溶液(pH 4.0 )为流动相,非线性梯度洗脱,流速1.0 mL/min,柱温30 ℃,紫外检测波长263 nm,并优化荧光激发和发射波长条件,实现了6种杂环胺的基线分离和4种杂环胺的高灵敏度荧光检测.本方法中荧光和紫外检测器的检出限分别为0.0018～0.0084 mg/L和0.093～0.609 mg/L(S/N=3),相关系数在0.9920～0.9999之间,RSD小于5.9%,平均回收率为75.3%～111.6%,回收率相对标准偏差为1.7%～2.3%,具有较高的精确度和准确度.     

Transparent and UV-Reflective Photonic Films and Supraballs Composed of Hollow Silica Nanospheres

For an optically transparent, UV-reflective film, hollow silica nanospheres smaller than the visible wavelength (<λ_vis) are prepared and assembled into colloidal glasses, of which interstices are then backfilled with a polymer. The polymer refractive index is matched with the silica shell to minimize backscattering in the visible range, and the average distance between the hollow silica particles is adjusted by tuning the shell thickness to satisfy the interference resonance condition for a UV selective reflection. The resulting composite film shows a strong UV reflection as expected, but it is translucent in visible light due to non-negligible backscattering, which may be caused by large defects or fluctuation of the particle concentration. In order to avoid such backscattering, another polymer is introduced of which the refractive index is matched with the average refractive index of the hollow nanospheres. This allows an optically transparent film that selectively reflects the UV light. Furthermore, spherical aggregates of hollow silica nanospheres called “supraballs” are prepared and their average refractive index is matched with a solvent by adjusting the mixture ratio of water and ethylene glycol, which yields an optically transparent solution, selectively reflecting UV.     

The influence of dust particle geometry on its charge and plasma potential

In this paper, a self‐consistent numerical model describing the behaviour of plasma around isolated highly charged dust particles with different shapes of rotation figures is presented. Dust particles in the form of a sphere, oblate ellipsoids (disk‐like particles), and elongated ellipsoids (rod‐like particles) are considered in the presence of an external electric field. Using the developed model, self‐consistent distributions of a space charge and plasma potential are obtained around non‐spherical dust particles. These distributions are carefully analysed by decomposing them in a series of Legendre polynomials. Decompositions of these distributions are compared with particles of different geometry. In addition, for different geometries of dust particles, the dependencies of the charge of a dust particle on geometry in the absence of an external field are investigated.