高能电子束辐照模式蛋白辣根过氧化物酶的损伤作用研究

作为一种载能粒子,高能电子束具有能量利用率高、贯穿深度大、方便实用等优点,可以用来杀灭细菌和抑制病原体生长,因而被广泛应用于食品保质储藏和医疗卫生等方面。但是,对于高能电子如何与生物及其生物分子发生作用,以及作用的过程、方式、效果和机理等方面,人们还缺乏深入、细致的了解。本研究利用高能电子束辐照模式蛋白酶辣根过氧化物酶(HRP:horseradish peroxidase),研究了电子束对它的损伤作用和机理。研究发现,电子束损伤HRP 的方式主要通过羟基自由基破坏蛋白质肽链,同时,辐照产生的活性氧物质也会作用于HRP 分子活性中心引起其辅基血红素的损伤。这与我们以前研究的等离子体放电辐照HRP其损伤主要通过H2O2 作用于变性蛋白血红素引起酶失活有所不同。进一步,通过利用活性氧和自由基清除剂的方法,具体分析和阐明了电子束辐射条件下同活性氧和自由基在损伤HRP 过程中所起的破坏作用。As one kind of charged energetic particles, high-energy electron-beam (e-beam) can kill bacteria effectively; and because of its advantages of low-cost and high-efficiency, e-beam has been widely applied in food sterilization and storage industry as well as biomedical areas. However, currently we still lack the in-depth understanding of the mechanism of the interactions between high-energy particles and biological systems. To this end, we thus initiated the study of e-beam induced damage of horseradish peroxidase (HRP: horseradish peroxidase). Our results revealed that the e-beam induced damage of HRP was mainly through the hydroxyl radical attack on the polypeptide chains, and at the same time, the heme active site of HRP was also injured by the reactive oxygen species (ROS) produced by the electron-beam. This hydroxyl radical damage mechanism is different from the hydrogen peroxide damage mechanism that plays the dominant role in non-thermal plasma treatment as we reported previously. Moreover, by using the ROS and free radical scavengers, we analyzed and identified the major factors that contributed to the HRP damages.     

Construction and Application of DNAzyme-based Nanodevices

The development of stimuli-responsive nanodevices with high efficiency and specificity is very important in biosensing, drug delivery, and so on. DNAzymes are a class of DNA molecules with the specific catalytic activity. Owing to their unique catalytic activity and easy design and synthesis, the construction and application of DNAzymes-based nanodevices have attracted much attention in recent years. In this review, the classification and properties of DNAzyme are first introduced. The construction of several common kinds of DNAzyme-based nanodevices, such as DNA motors, signal amplifiers, and logic gates, is then systematically summarized. We also introduce the application of DNAzyme-based nanodevices in sensing and therapeutic fields. In addition, current limitations and future directions are discussed.     

A remarkable shape-catalytic effect of confinement on the rotational isomerization of small hydrocarbons

As part of an effort to understand the effect of confinement by porous carbons on chemical reactions, we have carried out density functional theory calculations on the rotational isomerization of three four-membered hydrocarbons: n-butane, 1-butene, and 1,3-butadiene. Our results show that the interactions with the carbon walls cause a dramatic change on the potential energy surface for pore sizes comparable to the molecular dimensions. The porous material enhances or hinders reactions depending on how similar is the shape of the transition state to the shape of the confining material. The structure of the stable states and their equilibrium distributions are also drastically modified by confinement. Our results are consistent with a doubly exponential behavior of the reaction rates as a function of pore size, illustrating how the shape of a catalytic support can dramatically change the efficiency of a catalyst.     

接枝改性羧甲基纤维素对铜离子的吸附研究

将离子型单体丙烯酸(AA)及非离子型单体丙烯酰胺(AM)接枝在羧甲基纤维素(CMC)上,通过协同作用提高材料的吸水性及吸水速率,并研究了其对铜离子的吸附性能.通过傅里叶红外(FTIR)对材料分析表明,从及AM成功接枝在CMC上;对吸附物进行了表面分析,扫描电镜图(SEM)显示吸附物表面有大量颗粒状物质,X射线能谱(XPS)证实材料表面吸附了铜离子;在浓度为10mmol/L的铜离子溶液中,CMC-g-P(AA-co-AM)材料的吸附容量为20.30mmol/g.     

Melting behavior of water in cylindrical pores: carbon nanotubes and silica glasses

We report a study of the effects of confinement in multi-walled carbon nanotubes and mesoporous silica glasses (SBA-15) on the solid structure and melting of both H(2)O and D(2)O ice, using differential scanning calorimetry, dielectric relaxation spectroscopy, and neutron diffraction. Multi-walled nanotubes of 2.4, 3.9 and 10 nm are studied, and the SBA-15 studied has pores of mean diameter 3.9 nm; temperatures ranging from approximately 110 to 290 K were studied. We find that the melting point is depressed relative to the bulk water for all systems studied, with the depression being greater in the case of the silica mesopores. These results are shown to be consistent with molecular simulation studies of freezing in silica and carbon materials. The neutron diffraction data show that the cubic phase of ice is stabilized by the confinement in carbon nanotubes, as well as in silica mesopores, and persists up to temperatures of about 240 K, above which there is a transition to the hexagonal ice structure.     

超高效液相色谱-四极杆-飞行时间质谱法快速筛查和确证渔药中86种非法添加化学品

建立了超高效液相色谱-四极杆-飞行时间质谱法快速筛查与确证渔药中86种非法添加禁限用药物的方法。渔药以80%(v/v)乙腈水溶液进行提取,通过稀释降低基质效应,采用ACQUITY PREMIER HSS T3色谱柱进行分离,以甲醇和0.1%甲酸水溶液作为流动相进行梯度洗脱,采用电喷雾双喷离子源(Dual AJS ESI)正离子模式分析检测。建立了86种药物的一级精确质量数据库和二级碎片质谱库。在全扫描采集模式下,以化合物的色谱保留时间、精确质量数、同位素分布和同位素丰度比定性;在Target MS/MS采集模式下,通过二级碎片离子的匹配进一步确证化合物,以准分子离子峰的峰面积定量,实现渔药样品中多目标药物的快速定性定量分析。86种药物在各自的线性范围内均呈现良好的线性关系,相关系数均大于0.99,中草药制剂和抗生素粉剂的定量限(LOQ)范围分别为1~15 mg/kg和5~75 mg/kg,添加回收率范围为76.8%~112.1%,相对标准偏差(RSD, n=3)小于11.7%。该方法快速、简便、准确、灵敏,适用于不同种类渔药中禁限用非法添加药物的高通量筛查。将该方法应用于浙江省渔用投入品质量安全监督抽检项目中,共筛查60个样品,其中8种中草药制剂筛查出说明书中未明确标明的药物成分,1种抗生素粉剂未检出有效成分。该研究为渔药的质量安全监控提供了有效的技术手段。     

Advanced TEM Characterization for Single-atom Catalysts: from Ex-situ Towards In-situ

Clean energy innovation has triggered the development of single-atom catalysts(SACs) due to their excellent catalytic activity, high tunability and low cost. The success of SACs for many catalytic reactions has opened a new field, where the fundamentals of catalytic property-structure relationship at atomic level await exploration, and thus raises challenges for structural characterization. Among the characterization techniques for SACs, aberration-corrected transmission electron microscopy(TEM) has become an essential tool for direct visualization of single atoms. In this review, we briefly summarize recent studies on SACs using advanced TEM. We first introduce TEM methods, which are particularly important for SACs characterization, and then discuss the applications of advanced TEM for SAC characterization, where not only atomic dispersion of single atoms can be studied, but also the distribution of elements and the valence state with local coordination can be resolved. We further extend our review towards in-situ TEM, which has increasing importance for the fundamental understanding of catalytic mechanism. Perspectives of TEM for SACs are finally discussed.     

基于DNA纳米结构的细胞间相互作用的调控

细胞通过化学信号、 电子交换和直接接触等方式交换彼此之间的物质和信息, 以调节生命体的生长发育. 因此, 细胞间的相互作用研究与调控在细胞功能的机制研究和疾病的诊断及治疗等领域具有非常重要的意义. DNA纳米结构具有易合成、 易修饰、 可编程性设计及生物安全性高等优点, 有望实现操作简单、 精确可调、 智能响应的细胞间相互作用调控, 受到了广泛关注. 本文综述了寡核苷酸链杂交、 受体-配体结合和核酸适体靶向识别等基于DNA纳米结构的细胞组装策略, 总结了pH调控、 金属离子调控和DNA链激活等细胞间相互作用的调控手段, 并重点介绍了其在细胞间作用力的测量和成像、 体外组织模型的构建、 细胞间的通讯交流和细胞免疫治疗等领域的应用. 最后对该领域进行了总结和展望, 希望为相关研究提供有益参考.     

模糊综合评判在步枪作战效能评估中的应用

从20世纪80年代至90年代开始,世界各主要军事大国均研制了本国的新一代步兵战斗用枪.本文应用模糊综合评判方法对两代(共10种)冲锋枪和自动步枪作战效能的评估和排序进行了讨论,并对其作战效能和技术水平进行了判断.所得结论对了解我军装备的先进程度,适应新时期军事科学和战备具有特别重要的意义.