高LET的7Li离子致DNA损伤的直接和间接作用研究

在HI-13串列加速器加速的具有高LET值的7Li离子辐照不同浓度的pUC19质粒DNA水溶液、加自由基清除剂(甘露醇)的DNA水溶液以及干状DNA样品,利用高分辨的原子力显微镜技术,研究7Li致DNA损伤的直接作用和间接作用.结果显示,在相同剂量下,7Li离子比低LET辐射能诱发更多的双链断裂,形成更多的集团损伤,使DSB的分布更局部和更密集.对于水溶液DNA,7Li离子的水辐解产生的自由基的间接作用在DNA分子链断裂的产生方面发挥着重要作用,而且自由基清除剂甘露醇能有效地保护DNA分子.     

高温高压换热器密封结构的分析

根据高温高压换热器的设计条件,从设计参数、材料选择、密封原理、结构特点等方面对炼油化工装置中常用的高温高压换热器密封结构进行了分析。     

新型滤波装置的研制

针对用户的特殊负荷状况以及滤波装置投入运行后可能出现的问题,进行了深入的研究与仿真。在常规滤波装置的基础上对结构形式进行了调整,提出了一种具有双支路、阻尼性和双断口开关的新型滤波装置。自投运以来运行效果良好,成功解决了用户特殊负荷所引起的电压质量问题,证明了方案的合理性。     

“双碳”下金属纳米颗粒优化暗发酵制氢策略及前景

氢能是“双碳”下推动化石能源低碳转型的重要方向,微生物暗发酵制氢是实现生物质绿氢转化的有效途径。其中,利用具有量子尺寸效应、比表面积大和电导率高的金属纳米颗粒（MNPs）优化暗发酵制氢技术是近年研究热点。综述和评论了国内外添加MNPs用于优化暗发酵制氢性能的作用机制、技术难点和制氢效果等,重点阐述并比较了铁、镍和锌基三类热门MNPs优化策略在提高产氢酶系活性、增强代谢产氢途径和优化微生物群落结构等方面的作用,展望了暗发酵制氢可深入MNPs优化氢化酶活性、拓宽生物质发酵底物以及产氢菌筛选和反应器设计、生物质发酵技术开发等研究方向和应用前景。     

An analysis of heat transfer in liver tissue during microwave ablation using single and double slot antenna

Microwave ablation (MWA) is a process that uses the heat from microwave energy to kill cancer cells. MWA is able to focus radiation on the desired areas without damaging the surrounding tissue, entail a control of heating power for appropriate temperature distribution. Slot coaxial antennas are the most popular antennas in MWA because of their small dimensions and low cost to manufacture. To effectively treat liver cancer, these antennas can be used to produce a highly localized specific absorption rate (SAR) and temperature distribution pattern. In this work, the interstitial MWA in liver by single and double slot antennas is carried out. This paper focuses on the influence of antenna type on microwave power absorbed, SAR and temperature distribution. The results show that the maximum SAR and temperature appears in the liver tissue in case of single slot antenna which are higher than those of double slot antenna. However, no clear difference between these two microwave coaxial antenna (MCA) models has been shown, due to the low microwave power input from the MCA during MWA process.     

PLC控制系统双机热备及可靠性设计与实现

可编程序控制器(PLC)是专门为工业生产环境设计的控制装置。总结了PLC控制系统的设计原则、内容、步骤和方法，并探讨了PLC双机热备用设计及可靠性设计方面要考虑的主要问题，结合工程设计经验提出可行的解决办法。     

反向映射法在双列圆锥滚子汽车轮毂轴承设计中的应用

通过对比分析国内外双列圆锥滚子汽车轮毂轴承产品系列的结构特征和参考目前国内(单列)圆锥滚子轴承设计方法,分析了反向映射法在双列圆锥滚子汽车轮毂轴承结构设计中的应用。     

Investigating the thermal,mechanical and thermal cyclic properties of plasma-sprayed Al2O3-7YSZ/7YSZ double ceramic layer TBCs

Double ceramic layer (DCL) TBCs consisting of a top 20 wt.% Al₂O₃-7YSZ layer and a bottom 7YSZ layer were desirably designed to achieve preferable performance while the thermal, mechanical and thermal cyclic properties were comprehensively investigated. Compared to the conventional 7YSZ TBCs, the thermal insulation properties of the DCL coating were significantly improved due to the increased oxygen vacancy concentration induced by Al₂O₃ addition while the thickness of the thermally grown oxides was diminished by the decreased oxygen diffusion rate. Furthermore, the improved fracture toughness of the DCL coating also prolonged the thermal cyclic life.     

ELECTROKINETIC EFFECTS: CARBONIC ANHYDRASE AND CO2 ELECTRODE DYNAMICS

It is well known that the dynamic response rate of the Severinghaus-type CO₂ electrode is improved significantly in some cases by addition of the enzyme carbonic anhydrase to the electrode assembly. Hysteresis in the response rate also is reduced. Experimental data and modelling results indicate that catalysis of the CO₂ hydration reaction in the bulk of the bicarbonate layer (the Nernst film) is not responsible for the improved response behavior, Evidence is presented to show that catalysis in the electrostatic double layer region at the glass electrode surface is a possible explanation. This proposed phenomenon may have widespread implications for the optimal design of analytical devices, commercial processes involving electrochemical phenomena, and may also provide insight into electrobiologi-cal processes.     

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.