Formation Mechanisms of Platelet Sr3Ti2O7 Crystals Synthesized by the Molten Salt Synthesis Method

The molten salt synthesis (MSS) method is utilized to synthesize the anisotropic platelet Sr₃Ti₂O₇ (S3T2) single-crystal particles. The aim of this study is to identify the essence of platelet Sr₃Ti₂O₇ crystal growth and guide the synthesis of anisotropic platelet SrTiO₃ crystals as well as various technologically important materials. Based on the results of X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy, the formation mechanism of platelet Sr₃Ti₂O₇ crystals conforms to a nucleation–structure rearrangement–dissolution–diffusion in situ epitaxial growth mechanism model. First, SrCO₃ reacts with TiO₂ to form submicrometer SrTiO₃ nuclei. Then, most of the nuclei surrounded by salt ions aggregate and rearrange to form a large SrTiO₃ matrix. The structural rearrangement and the subsequent in situ epitaxial growth processes control the morphology, composition, and size of the final Sr₃Ti₂O₇ crystals. In the synthesis process, the conversion between SrTiO₃ and Sr₃Ti₂O₇ is as follows: and the crystallographic orientation relationship between Sr₃Ti₂O₇ and SrTiO₃ in the interface is (100)_S3T2//{100}_ST, (010)_S3T2//{010}_ST, and (001)_S3T2//{001}_ST.     

能有效抑制碱集料反应的复合矿物掺合料

研究了在80℃养护条件下，掺加复合矿物掺合料对含沸石化珍珠岩集料砂浆碱一集料反应膨胀的影响。研究发现．混凝土中复合矿物掺合料掺量为25％和40％时，可以有效抑制碱硅酸反应，且40％掺量时抑制作用更强。     

Synthesis and characterization of poly(vinyl chloride‐co‐vinyl acetate)‐graft‐poly[(meth)acrylates] by atom transfer radical polymerization

The graft polymerization of methyl methacrylate and butyl acrylate onto poly(vinyl chloride‐co‐vinyl acetate) with atom transfer radical polymerization (ATRP) was successfully carried out with copper(I) thiocyanate/N,N,N′,N′,N″‐pentamethyldiethylenetriamine and copper(I) chloride/2,2′‐bipyridine as catalysts in the solvent N,N‐dimethylformamide. For methyl methacrylate, a kinetic plot of ln([M]₀/[M]) (where [M]₀ is the initial monomer concentration and [M] is the monomer concentration) versus time for the graft polymerization was almost linear, and the molecular weight of the graft copolymer increased with increasing conversion, this being typical for ATRP. The formation of the graft polymer was confirmed with gel permeation chromatography, ¹H‐NMR, and Fourier transform infrared spectroscopy. The glass‐transition temperature of the copolymer increased with the concentration of methyl methacrylate. The graft copolymer was hydrolyzed, and its swelling capacity was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 183–189, 2005     

新试剂DBPMP用于铀的萃取光度法测定研究

本文将新型螯合萃取剂DBPMP用于铀的萃取光度法研究。提出了一种选择性好,灵敏度高的测定方法。铀浓度在0～5.0mg/25ml范围内符合比尔定律。将本法用于矿石中铀的测定,结果满意。     

炭黑填充硬聚氯乙烯的改性

为使聚氯乙烯具有抗静电性能,采用加入具有导电性填料的方法,但加入大量的填料,会使硬聚氯乙烯的冲击性能降低,加工性能变差。本文是在以炭黑为填料的基础上,研究不同的改性剂和加工助剂改进硬聚氯乙烯的效果,结果表明,加入冲击改性剂和加工助剂后,大大增加了硬聚氯乙烯的冲击强度,且加工性能也得到改善,同时由于炭黑具有补强效果,其拉伸强度和弯曲强度在加入改性剂后也能满足使用要求。     

A high propylene productivity over B2O3/SiO2@honeycomb cordierite catalyst for oxidative dehydrogenation of propane

Boron-based metal-free catalysts for oxidative dehydrogenation of propane (ODHP) have drawn great attention in both academia and industry due to their impressive activity and olefin selectivity. Herein, the SiO₂ and B₂O₃ sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B₂O₃ loadings (0.1%-10%) and calcination temperatures (600, 700, 800 ℃). SiO₂ obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant Si-OH groups. The welldeveloped straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity (GHSV) and the thin wash-coated B₂O₃ layer can effectively facilitate the pore diffusion on the catalyst. The prepared B₂O₃/SiO₂@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity (86.0%), olefin selectivity (97.6%, propylene and ethylene) and negligible CO₂ (0.1%) at 16.9% propane conversion under high GHSV of 345,600 ml·(g B₂O₃)^-1·h^-1, leading to a high propylene space time yield of 15.7 g C₃H₆·(g B₂O₃)^-1·h^-1 by suppressing the overoxidation. The obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels.     

碳化硅纳米粉体研究进展

碳化硅纳米粉体性能优于传统的碳化硅粉体，能够达到高新技术领域的严格要求，具有更为广泛的用途。综述了近年来在高新技术领域发展起来的碳化硅纳米粉体的制备方法，对一些新的制备方法进行了重点介绍，阐述了各种方法的基本原理、特点及研究现状，并对各种方法进行了比较。碳热还原法原料便宜，质量稳定，易实现工业化生产；液相法可制得纯度高的纳米级微粉；气相法是目前比较先进的方法，但不易实现大批量生产。未来碳热还原法将继续占主导地位，提出了该领域科学工作者的努力方向。     

一种电感式ID卡及其阅读器

采用ARM单片机LM3S9B96控制单相桥开关,以恒流源向原边线圈充放电,可以实现电感式阅读器和ID卡的功能,原、副边线圈一样,只有5匝。线圈之间的轴向距离为2.4 mm,两线圈的径向偏差允许在10 mm以内。工作周期分成充电时段和测量时段两部分,测量一次ID码(32-bit)的时间为16 ms。设计了试验电路和控制程序,测量出了ID卡上的电源特性,做了波形分析。通过试验证明可以实现ID卡的功能。     

醋酸乙烯-丙烯酸无皂乳液共聚的研究

以醋酸乙烯(VAc)为主单体,丙烯酸(AA)为改性功能单体,以半连续加料方式进行无皂乳液共聚过程,得到了稳定且固含量为30%左右的乳液。探讨了功能单体AA含量、反应温度等对共聚的影响。采用FT-IR、粒径分析等方法对共聚物的组成、乳胶粒子的尺寸及分布进行了分析表征。结果表明:在(65±2)℃下聚合,所得乳液稳定性好、转化率高、反应完全,且随着功能单体AA含量的增加,乳液黏度上升、单体转化率下降、乳胶粒粒径变小且粒径呈单分散性。     

Trusted Integrated Circuits: The Problem and Challenges

Hardware security has become more and more important in current information security architecture. Recently collected reports have shown that there may have been considerable hardware attacks prepared for possible military usage from all over the world. Due to the intrinsic difference from software security, hardware security has some special features and challenges. In order to guarantee hardware security, academia has proposed the concept of trusted integrated circuits, which aims at a secure circulation of IC design, manufacture and chip using. This paper reviews the main problems of trusted integrated circuits, and concludes four key domains of the trusted IC, namely the trusted IC design, trusted manufacture, trusted IP protection, and trusted chip authentication. The main challenges in those domains are also analyzed based on the current known techniques. Finally, the main limitations of the current techniques and possible future trends are discussed.