化学标记语言及其应用

化学标记语言CML是可扩展标记语言XML的一个应用,用于表示化学信息。CML可以表示原子、分子和晶体学信息。其他的分子格式文件可以转换成为CML文档而没有信息的丢失。本文详细回顾了CML的起源、设计目标、发展历程、现状和应用,分析了CML未来的应用和发展。     

Analysis of chemical compounds and toxicological evaluation of Forsythia suspensa leaves tea

To determine the compositions of Forsythia suspensa leaves tea (FSLT) and its safety, the chemical compounds were analysed with some methods, and the toxicity was evaluated in Kunming mice and Wistar rats. The results showed that FSLT contained rich flavonoid, lignans, triperpene acids, amino acids, and mineral elements. In the acute toxicity study, none of the mice died, and no obvious poisoning symptoms were observed after 14 days in mice at the dose of 15 mg/g·body weight (bw) FSLT; in the sub-chronic toxicity, no abnormal or dead rat was found at the dose of 1, 3, and 10 mg/g·bw during 90 days feeding administration; there was no significant difference in bw and food consumption; no significant differences were found in each hematology and serum biochemistry parameter and organ/body weight ratio comparing with the control experimental group. The results revealed that the FSLT has low or no toxicity via oral administration. Therefore, FSLT is very suitable and safe to be used as a new resource food.     

纸片型1-MCP处理对‘朝霞’水蜜桃抗病物质代谢的影响

目的 研究1-甲基环丙烯(1-methylcyclopropene, 1-MCP)处理对采后水蜜桃果实病害发生的影响。方法 ‘朝霞’水蜜桃果实采后通过0(对照组)和1.2 μL/L纸片型1-MCP分别进行处理12 h,在(25±1)℃、85%相对湿度下贮藏,每2 d取样,评价和测定水蜜桃果实感病指数、抗病相关物质(总酚、木质素)含量及抗病相关酶[过氧化物酶(peroxidase, POD)、多酚氧化酶(polyphenol oxidase, PPO)、几丁质酶(chitinase, CHI)、苯丙氨酸解氨酶(phenylalanine ammonia-lyase, PAL)和β-1,3-葡聚糖酶(β-1,3-glucanase, GLU)]活性。结果 与对照组水蜜桃果实相比,纸片型1-MCP处理能有效延缓水蜜桃果实采后感病指数的上升,维持较高的果实果肉木质素和总酚含量,保持较高的果肉POD、PPO、PAL、CHI和GLU活性。结论 纸片型1-MCP处理可升高水蜜桃果实采后果肉抗病相关酶的活性,加速果肉累积抗病物质,进一步提升水蜜桃果实的采后抗病能力,最终减慢果实采后发生病害及延长果实采后贮藏期。     

Selective copolymerization of carbon dioxide with propylene oxide catalyzed by a nanolamellar double metal cyanide complex catalyst at low polymerization temperatures

Traditional cobalt-zinc double metal cyanide complex [Zn-Co(III)DMCC] catalysts could catalyze the copolymerization of carbon dioxide (CO₂) with propylene oxide (PO) to afford poly (propylene carbonate) (PPC) with high productivity. But the molecular weight (MW) of PPC and the polycarbonate selectivity were not satisfied. In this work, by using a nanolamellar Zn-Co(III) DMCC catalyst, the CO₂-PO copolymerization was successfully performed to yield PPC with high molecular weight (M_n: 36.5 kg/mol) and high molar fraction of CO₂ in the copolymer (FCO₂: 74.2%) at low polymerization temperatures (40∼80 °C). Improved selectivity (FCO₂: 72.6%) and productivity of the catalyst (6050 g polymer/g Zn) could be achieved at 60 °C within 10 h. The influences of water content on CO₂-PO copolymerization were quantitatively investigated for the first time. It was proposed that trace water in the reaction system not only acted as an efficient chain transfer agent, which decreased MW of the resultant copolymer, but also strongly interacted with zinc site of the catalyst, which led to low productivity of PPC and more amounts of cyclic propylene carbonate (cPC). These conclusions were also supported by the apparent kinetics of CO₂-PO copolymerization. ESI-MS results showed that all polymers have two end alkylhydroxyl groups. It was thus proposed that the alkylhydroxyl groups came from the initiation reaction of Zn-OH in the catalyst and the chain transfer reaction by H₂O. The proposed mechanism of chain initiation, propagation and chain transfer reaction were proved by the experimental results.     

Design and Performance of an AIGaN-Based p-i-n Ultraviolet Photodetector

An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values. It is indicated that the changing of responsivity with increase of bias can not be attributed to the expansion of depletion layer as it is believed, but to two reasons： 1） the effect of GaN/AlGaN heterojunction barrier to block the electrons decreases with higher bias and 2） the recombination rate of excess carriers decreases due to the building up of an electric field in depletion region. At zero bias, the simulated responsivity reaches its maximum of 0.12 A/W with quantum efficiency of 55.1%. The measured peak responsivity is more than 0.09 A/W with quantum efficiency greater than 41.6%. The experimental data are almost consistent with the results of the simulation.     

锶废渣制备锶盐酸浸取工艺关键参数的实验研究

以碳还原天青石生产碳酸锶的锶废渣为原料,采用盐酸为浸取剂,研究了锶废渣制备锶盐酸浸取工艺中锶渣粒径、浸取温度、浸取时间、溶液酸度等参数对锶浸取率的影响。在此基础上利用正交实验对锶渣酸浸取工艺进行优化。得到锶废渣酸浸取锶的最佳工艺：锶渣粒径为0.062 mm、反应时间为2 h、反应温度为30 ℃、浸取液pH为0.1。该研究可为提高锶资源的利用率提供参考。     

无线移动网络跨可信域的直接匿名证明方案?

基于信任委托的思想,提出一种移动环境下的跨可信域的直接匿名(direct anonymous attestation,简称DAA)证明方案,采用代理签名技术和直接匿名证明方法,实现对移动终端在多可信域之间漫游时的可信计算平台认证,并在认证过程中协商会话密钥,增强了远程证明体系的安全性。利用 Canetti-Krawczyk(CK)模型对方案的认证协议的认证安全性和匿名安全性进行了形式化分析和证明。分析表明,该方案能够抵抗平台伪装攻击和重放攻击,其性能适用于无线网络环境。     

Design of adjustable-dual-beam and constant-polarization antenna by odd mode of coupled-patch in central symmetry

In this article, two coupled patch elements in central symmetry are used to produce a pair of even/odd characteristic modes with single-/dual-beams. It is found that the pointing direction of dual-beam could be adjusted in both horizontal and vertical planes with unchanged polarization. Common-fed configuration is adopted to effectively excite the odd mode and fully suppress the even mode. Modal impedance analysis is performed for the proposed antenna to determine the two feeding positions. A prototype antenna with its dual-beam rotated by 45° in horizontal plane and inclined by 40° in vertical plane is fabricated and measured. The antenna possesses a 10-dB impedance bandwidth of 0.73% and a radiation gain of 7.0 dBi.     

面向应用服务级目标的虚拟化资源管理

在虚拟环境中实现应用服务级目标,是当前数据中心系统管理的关键问题之一.解决该问题有两个方面的要求:一方面,在虚拟化层次和范围内,能够动态和分布式地按需调整虚拟机资源分配;另一方面,在虚拟化范围之外,能够控制由于虚拟机对非虚拟化资源的竞争所导致的性能干扰,实现虚拟机性能隔离.然而,已有工作不适用于虚拟化数据中心场景.提出一种面向应用服务级目标的虚拟化资源管理方法.首先,该方法基于反馈控制理论,通过动态调整虚拟机资源分配来实现每个应用的服务器目标;同时,还设计了一个两层结构的自适应机制,使得应用模型能够动态地捕捉虚拟机资源分配与应用性能的时变非线性关系;最后,该方法通过仲裁不同应用的资源分配请求来控制虚拟机在非虚拟化资源上的竞争干扰.实验在基于Xen的机群环境中检验了该方法在RUBiS系统和TPC-W基准上的效果.实验结果显示,该方法的应用服务级目标实现率比两种对比方法平均高29.2%,而应用服务级目标平均偏离率比它们平均低50.1%.另一方面,当RUBiS系统和TPC-W基准竞争非虚拟化的磁盘I/O资源时,该方法通过抑制TPC-W基准28.7%的处理器资源需求来优先满足RUBiS系统的磁盘I/O需求.     

无缆化工管道机器人的研究进展

首先讨论了化工管道机器人能源供给的几种方式,并提出了无缆的供能方式才是未来化工管道机器人的发展方向。综述了国内外这方面的研究进展,并找出了无缆化工管道机器人所存在的问题。最后说明我们只有在现存的问题上取得关键性的技术突破才能使无缆化工管道机器人的应用成为现实。