Microstructure study of Sm,Mn-modified PbTiO3 piezoelectric ceramics by XRD profile-fitting technique

By using the X-ray diffraction profile-fitting technique, the microstructures of Sm, Mn-modified PbTiO₃ piezoelectric ceramic discs, including ferroelectric domain sizes, microstrains, and their variations with the poling strength have been quantitatively investigated. The results manifest that the modified PbTiO₃ ceramics contain a high density of domain walls due to the presence of finely-divided coherent domain structures (tens of nanometres in dimension). The poling treament can evidently influence the domain-size distribution, with a more homogeneous microstructure being developed; however, it simultaneously causes high anisotropic microstrains within the structure which, together with the high density of domain walls, is expected to be responsible for the unusual high electromechanical coupling properties possessed by this material.     

Entrapping multifunctional dendritic nanoparticles into a hydrogel for local therapeutic delivery and synergetic immunochemotherapy

Nano Research - Developing multifunctional nanoparticles to support new therapy models is a promising and challenging task to address the current dilemma on antitumor treatment. Herein, we...     

网页数据智能抽取方法

根据所要抽取网页的特点，提出了一种基于网页结构和ontology领域知识的自动网页数据抽取。并且使得ontology在数据抽取的过程中自动扩充。     

A novel method of structural shape optimization coupling BEM with an optimization method based on biological growth

Local stress peaks are the main reason for fatigue failure of structures, and therefore many researchers make every effort to search for effective methods of structural shape optimization. Mattheck and Burkhard (1990) have developed a method by simulating the self-optimization mechanism of biological growth, using FEM. BEM is a very effective method in which only the boundary is divided into elements, and particularly, accurate results at the boundary can be obtained. It is obvious that BEM is a more suitable analysis method for structural shape optimization than FEM. Coupling BEM of three-dimensional thermoelasticity problems with an optimization method based on biological growth, a novel method of structural shape optimization is successfully developed by the authors. Several examples are used to demonstrate that the method is successful and efficient.     

Preparation of alkoxides for the synthesis of ceramics

The literature is reviewed to summarize methodologies for synthesizing metal alkoxides applicable as organic precursors to high-purity, well-characterized ceramic powders. Typical examples of preparation techniques, patents, and commercial manufacturing methods are provided, and special precautions noted. Basically, metal alkoxide synthesis is determined by the electronegativity of the metal concerned; synthetic routes may lead directly from the metal or a metal halide, or may be indirect, involving alcoholysis.     

Applicability assessment of a real-time PCR assay for the specific detection of bovine,ovine and caprine material in feedstuffs

A TaqMan real-time polymerase chain reaction (PCR) method was developed for specific detection of bovine, ovine and caprine processed animal protein (PAP) in industrial feedstuffs. The method uses species-specific primers and probes targeting short mitochondrial D-loop sequences, and a positive amplification control based on 18S rRNA gene. The applicability of the real-time PCR protocol was assessed through analysis of 126 industrial feed samples that were manufactured to reproduce rendering processes of commercial feeds destined for farmed animals. The assay successfully classified samples as positive or negative according to the ruminant composition, enabling qualitative detection of banned material in feeds at levels as low as 0.1%. Although the method provides quantitative potential, results suggest that the real quantitative capability of the assay is limited by the existing variability in terms of composition and processing treatments of the feeds, which affect the amount and quality of amplifiable DNA.     

低温烧成高纯Al_2O_3多孔陶瓷膜支撑体的制备

为了降低高纯Al2O3(α-Al2O3质量含量≥99%)多孔陶瓷膜支撑体烧成温度,以粒径为30μm的α-Al2O3为原料,分别添加TiO2和TiO2/Cu(NO3)2为烧结助剂,通过干压成型和挤出成型制备片状和管式多孔支撑体。Al2O3-TiO2和Al2O3-TiO2-CuO体系分别在高温下出现的液相低共熔物促进了多孔支撑体的烧结。当氧化铝支撑体中添加0.5%(摩尔分数,下同)TiO2+0.5%Cu(NO3)2后,在1600℃的烧成即可获得机械性能高、渗透性能好和耐酸碱腐蚀性能优异的管式支撑体。在压力为0.1MPa时,支撑体的水渗透通量为12.1m3/(m2·h),弯曲强度为44.5MPa。经过80℃,含10%(质量分数,下同)HNO3的溶液腐蚀800h及80℃,含10%NaOH的溶液1200h后,支撑体的质量损失率分别为1%和0.35%。     

Al(H_2PO_4)_3和H_3PO_4改性AlN粉末的研究

采用机械球磨法,以Al(H2PO4)3和H3PO4为改性剂,制备了具有较高抗水解能力的AlN粉末,研究了改性AlN粉末在水基球磨过程中的稳定性。通过XRD,FT-IR,SEM,TG-DSC和氮含量测定对改性前后AlN粉末进行了表征。改性AlN粉末在60℃水中浸泡24h后,其w(N)为32.97%,且其XRD谱中未发现Al(OH)3相,其抗水解能力得到显著提高。改性AlN粉末在水中高速球磨16h后,其w(N)约为32%,AlN悬浮液的pH值约为6,说明改性AlN粉末在水中球磨过程中具有较好的稳定性。     

水下枪械膛口速度的统计试验及其结果分析

为研究水下枪械弹丸出枪口的运动速度变化规律,提出了一种膛口速度测试的新方法:在距枪口3 m内,采用一对标准线圈靶,在多个位置点对弹丸进行多次重复测量,并以各位置点的平均速度进行拟合,再反推到枪口,得到枪口速度及弹丸在距枪口3 m内的速度变化规律.该方法避免了常规多个线圈靶同时测量时由于各线圈靶的动态特性不一致而造成的测...     

液相还原法制取纳米银粉的研究

以硝酸银为原料,水为反应介质,聚乙烯吡咯烷酮为保护剂,甲酸铵作为还原剂,利用普通液相还原法常温一步直接制备得到平均粒径在10nm左右的纳米级银粉。采用XRD、EDS、TEM等测试手段,对所制得的纳米银粉进行了表征。并简要讨论了纳米银粉制备过程中的各类影响因素。