Random stacking template of polymer spheres and water soluble particles to fabricate porous hydroxyapatite with interconnected pores

Particle stacking simulation is applied in the fabrication of porous hydroxyapatite (HA) ceramics to predict the relationship between the template preparation process and the porosity of porous ceramics. The stacking of multi-diameter spherical particles, such as polymer spheres and NaCl particles, in three-dimensional space is simulated by using continuous generation method. The porosity of porous HA is predicted by calculating the stacking density of large spheres (the ratio of large sphere volume and container volume). The model of three-dimensional random stacking spheres is implemented by using the C++ program. Porous HA ceramics with interconnected spherical pores were fabricated by slipcasting which the use of a polymer template. Templates were produced by randomly stacking polymer spheres and NaCl particles. The arithmetic average error between the porosity of porous HA ceramics and the stacking density of polymer spheres (large spheres) is 3.52%. Simulation results obtained by using the proposed method are consistent with the experimental results.     

Effects of liquid phases on densification of TiO2-doped Al2O3–ZrO2 composite ceramics

This study investigated the densification behaviors and microstructural evolution of Al₂O₃–ZrO₂ (3Y) composite ceramics doped with four different amounts of TiO₂ (0, 1, 4, and 8 wt%; denoted as 0T, 1T, 4T, and 8T, respectively) to clarify the effect of TiO₂ dopants on densification. The shrinkage rate during densification increased with the increase in the amount of TiO₂. The development of grain boundary feature was also examined. The undoped ceramic showed clean grain boundaries. Thin liquid grain boundary phases were observed in 1T, whereas large liquid phases were found on the grain boundary and at the junction pockets in 4T and 8T. The results were discussed in terms of the relationship between densification and grain boundary feature.     

基于JAIN SLEE的业务逻辑执行环境的设计与实现

本文简要分析了下一代业务逻辑执行环境(SLEE,Service Logic Execution Environment)JAIN SLEE规范,在此基础上给出了基于规范的SLEE设计与实现.     

合成皂石为前驱物制备高稳定性含镍介孔分子筛

以无机盐为原料通过控制pH值,用水热法合成含Ni皂石,并以此皂石为前驱物、十六烷基三甲基溴化铵为模板剂,制备含Ni介孔分子筛.用X射线粉末衍射、Fourier变换红外光谱、程序升温还原、透射电子显微镜、比表面积和孔径测定等仪器和方法表征样品的物化性能.结果表明:制得了有序性好的含Ni介孔分子筛,其比表面积为811.2m2/g,平均孔径为3.64nm.所制备的含Ni介孔分子筛经850℃焙烧3h或100℃水热处理10d后仍然具有介孔结构,说明样品具有高的(水)热稳定性.     

一种带摆动机构的线锯床的设计

由于线锯切割具有切片薄、表面翘曲变形小、厚薄均匀和切口损失小等优点,被广泛用于单晶硅切片加工。本文介绍了单晶硅切片加工的常用设备及其特点,分析了主要影响因素,设计了一种带摆动机构的线锯床。该摆动机构由伺服电机驱动并自动控制,与传统线锯床相比,其锯丝可绕其中点转动,加工圆形工件时,能保持锯丝与工件的接触长度最短或不变。本文还指出了该锯床制造中的几点工艺问题。     

基于DIgSILENT的中压配电网合环电流计算与仿真分析

中压配电网合环操作可能会产生较大的合环稳态电流与合环冲击电流,将对电网的安全稳定运行造成巨大影响.为验证在实际工程中合环判别的适用性,提出了一种基于合环电流的中压配电网合环判定方法.首先,对叠加法和公式法两种合环稳态电流计算方法进行了分析,推导了最佳频率下合环冲击电流的解析公式.然后,结合合环的稳态电流与冲击电流构建合...     

基于BEPCⅡ数字束流位置测量系统电子学系统的设计与实现

BEPCⅡ加速器的束流位置测量系统（BPM）模拟电子学经过十余年的运行逐渐老化,故障率上升,亟需进行升级改造。本文根据该需求,自行设计了基于BEPCⅡ系统参数的数字BPM电子学系统,内容包括模拟信号处理电子学、数字信号处理电子学、BPM固件算法逻辑、数据获取软件以及系统测试等多个部分。设计的数字BPM电子学系统经实验板级性能测试、实验室系统测试以及在线束流测试,结果表明该系统能满足BEPCⅡ装置对束流位置测量的需求。     

不同矿区天然隐晶质石墨对天然橡胶性能的影响

选用两种不同矿区的天然隐晶质石墨材料,经过超细粉体制备研磨后用于天然橡胶,探究了不同矿区隐晶质石墨在天然橡胶中的溶解度和对性能的影响并研究了粒径和混合工艺对天然橡胶性能的影响规律。研究表明,不同矿区隐晶质石墨因集合体构成不同,在橡胶中的溶解度差异较大;粒径大小是影响橡胶性能的关键参数;混合工艺对橡胶性能的影响更为明显。     

Swelling behavior of expandable poly(methyl methacrylate-acrylic acid)/polymethyl methacrylate bio-composites with different crosslinking densities

The volume shrinkage of poly(methyl methacrylate-acrylic acid) (PMMA) bone cement was mainly tackled by the different types and contents of the hydrophilic additives. While the crosslinking density was assumed to regulate the hydrophilic group amounts and 3D network structures in the additives, which influenced the absorption and swelling capacity of the PMMA-based bone cement. In this study, the expandable PMMA/polymethyl methacrylate bio-composites (EBC) with different N, N-methylenebisacrylamide (MBA) contents were synthesized to investigate the relationship between the crosslinking density and swelling performance, and also promoted the absorption and swelling properties before the solidification of EBC. The results demonstrated that the equilibrium absorption ratio and the equilibrium swelling ratio both exhibited a normal distribution with the various MBA content. In addition, the controlled absorption ratio (7.3–60.2%) and swelling ratio (8.5–61.8%) of EBC could be obtained by altering crosslinking density in the system. Furthermore, EBC could obtain a similar equilibrium absorption ratio and equilibrium swelling ratio with different mechanical properties, which provided more options for meeting the requirements of EBC in different clinical settings.     

大孔树脂对大豆糖蜜超滤液的脱色效果研究

比较了3种不同的大孔树脂D201、D315、AB-8对大豆糖蜜超滤液的脱色效果。研究结果表明,AB-8树脂具有较高的脱色率和较低的总糖损失率,且解析容易。最佳的操作条件为：室温、pH4．0、流速1．5BV／h。