一种新颖的测定和分析羟自由基氧化损伤RNA及其分子机理的化学发光体系

近年来，羟自由基（^.OH)对DNA氧化损伤已受到广泛关注，但是很少研究^.OH对RNA的氧化损伤。其实，RNA与DNA一样，也是核酸的两大组分之一，也有许多重要功能。所以^.OH攻击RNA也会引起重后果，会造成细胞功能衰退甚至细胞死亡等。为此，我们建立了Vit.C-CuSO4-Phen-H2O2-PNA这一产生和测定^.OH氧化损伤RNA的化学发光体系，以便加强^.OH氧化损伤RNA的研究。通过对本体系测定条件的研究，得出了本体系最佳组方是：Vit.C,CuSO4,Phen,H2O2和RNA，浓度分别为350μmol/L,55μmol/L,350μmol/L,0.2mol/L和20μg/mL,体系pH为5．5，体系终体积为1mL。随后，利用本体系检测了槲皮素，咖啡酸，黄芩甙和芦丁抗^.OH氧化损伤RNA的作用，发现这四种抗氧化剂均能有效抑制^.OH氧化损伤RNA的分子机理，结果发现，^.OH清除剂硫脲几乎抑制全部发光，推测是因硫脲清除了引发剂^.OH所致；O^-.2清除剂SOD只能抑制小部分发光；^1O2清除剂叠氮化钠和苯甲酸都能抑制绝大部分发光。这些事实提示，^.OH是RNA氧化损伤的引发剂；O^-.2只是导致RNA氧化损伤的次要因素，^1O2才是导致RNA氧化损伤的最主要因素。     

香叶天竺葵叶非精油组分清除自由基、抗氧化作用

活性氧与许多疾病的发生和发展密切相关,与食品的氧化也息息相关。所以筛选天然抗氧化剂显得非常重要。因此,分别采用水、乙醇和乙酸乙酯提取法从提取精油后的残渣中提取香叶天竺葵叶非精油有效组分,并分别采用超氧阴离子自由基(O2-·),羟自由基(·OH),过氧亚硝基(ONOO-)和.OH氧化损伤DNA的四种化学发光体系和二苯代苦味肼基自由基(DPPH·)和脂质过氧化两种比色体系检测香叶天竺葵叶非精油组分清除多种自由基、活性氧的能力以及对DNA的保护作用。结果表明,香叶天竺葵叶非精油组分的3种不同提取物均能有效地清除O2-·、·OH、DPPH·和ONOO-,减轻或消除·OH对DNA的氧化损伤,抑制脂质过氧化,是一种有效的、多功能的天然抗氧化剂和自由基清除剂。由于非精油组分是从制取精油组分后的残渣中提取的,提取装置和工艺也非常简单,故本研究不仅为香叶天竺葵种植效益的提高和综合利用提供了可能,也为天然香料加工后废弃物的开发研究提供了资料,对经济环境保护和资源的再利用也有借鉴意义。目前国内外对芳香植物的研究与开发主要聚焦于精油组分,而研究表明,更多的抗氧化物质是存在于非精油组分中,由于非精油组分是从制取精油组分后的残渣中提取的,并且提取装置和工艺简单,是值得进一步开发利用的天然产物。     

雷震子护康胶囊制剂抗氧化和对DNA损伤保护作用研究

雷震子护康胶囊以低聚原花青素、灵芝多糖、绞股蓝总皂甙及一定量的维生素C等为主要成分而制成，有多种保健功能。为研究该复方制剂的抗氧化作用，采用七种化学发光体系和一种比色体系研究了雷震子直接清除活性氧、活性氮和对^.OH引起的DNA损伤的保护作用。结果表明雷震子能有效清除O2^-.、^.OH、H2O2、ONOO^-和全血嗜中性白细胞“呼吸爆发”产生的活性氧，抑制脂质过氧化，保护DNA免受^.OH的氧化损伤。这些结果提示，雷震子是一种有效的抗氧化复方制剂，其强烈的抗氧化活性可能是其保健功能的重要药理基础之一。     

中药巴戟天抗自由基活性的研究

基于Fenton反应和抑制邻苯三酚自氧化原理,分光光度法测定体系吸光度的变化研究巴戟天抗自由基活性,证明巴戟天对羟自由基(·OH)及超氧阴离子自由基(O2-·)均有良好的清除作用,清除率与巴戟天的浓度有一定的量效关系。     

百合提取液对羟自由基的清除作用

在Co2+-H2O2产生羟自由基的稳定体系中,以溴邻苯三酚红为显色剂,用分光光度法测定吸光度的变化值,研究百合提取液在此体系中清除羟自由基的作用,通过常见抗氧化剂对羟自由基清除的量效关系,判断方法的可行性.对照实验表明,百合提取液对羟自由基有较好的清除效果.     

流动注射化学发光法及光度法用于巴戟天提取液抗氧化活性的研究

将中药巴戟天提取液加入鲁米诺-H₂O₂-CuSO₄化学发光体系,测量其发光强度, 根据系统化学发光被抑制的程度可以评价巴戟天的抗氧化活性,并将巴戟天与抗坏血酸的抗自由基活性进行了对比实验,实验证明巴戟天提取液具有明显的抗自由基活性;采用分光光度法测定体系吸光度的变化来研究巴戟天对OH·及O₂-·自由基的清除作用,以抗坏血酸作阳性对照,结果发现：巴戟天对OH·及O₂-·自由基均有良好的清除作用,结果较为满意。提示中药巴戟天可作为潜在的具有抗氧化活性的天然药物。     

信阳红、绿茶提取物的抗氧化能力

以信阳红、绿茶为原料,水和95％的乙醇为提取溶剂,考察提取物对羟自由基（·OH）和超氧阴离子自由基（·O2-）的清除作用.结果显示,两种溶剂红、绿茶提取物对两种自由基均有显著地清除作用,且红、绿茶水提取物对两种自由基的清除能力均高于乙醇提取物,两种溶剂红茶提取物对羟自由基（·OH）清除能力大于绿茶,绿茶乙醇提取物对超氧阴离子自由基（·O2-）清除能力大于红茶.     

过氧化物酶-辅酶NADH催化O2/H2O2产生经基自由基研究及其氯苯处理初探

利用光谱学和波谱学手段研究HRP-NADH-O2/H2O2体系中自由基生成机理及HRP状态的变化,并应用该酶体系对有机污染物氯苯进行初步处理研究.紫外可见光谱表明酶辅酶体系在过氧化氢的氧化下,产生了强氧化性的化合物III,说明可能产生羟基自由基.分别选用DMPO和POBN两种自由基捕获剂,通过电子自旋顺振(EPR)检测到HRP+NADH体系在O2和H2O2存在下产生超氧阴离子自由基(O2-)和羟自由基(·OH).在开始10 min内过氧化物酶主要以化合物III形式存在,随后转化为HRP,同时检测出较高浓度的·OH.O2有存在条件下产生·OH浓度大约是单独H2O2存在条件下的4倍.超氧化物歧化酶(SOD Zn-Cu)在HRP+NADH+O2体系中能消除由NADH还原O2产生的(O2-.从而抑制·OH生成.HRP+NADH体系相对于传统酶法处理能提高20%左右的酶活力,说明酶-辅酶体系能够提高酚类化合物的去除效率.实验条件下HRP+NADH+ H2O2和HRP+NADH十H2O2+O2体系对于非酚类污染物氯苯的去除率分别到达了24.6%和48.20,,远高于传统酶法的1.42%,突破了传统酶处理只能处理酚类污染物的局限性.     

掌裂草葡萄提取物的抗氧化性

通过测定掌裂草葡萄提取物对羟自由基(.OH)的清除率、对超氧阴离子(O2-.)的抑制率,研究其抗氧化活性。结果显示:提取物对羟自由基(·OH)、超氧阴离子(O2-·)有较强的清除抑制作用,并随着提取物添加量的增加,抗氧化作用以及对羟自由基及超氧阴离子的清除抑制作用也随之增强。     

甘青铁线莲花不同溶剂提取物的抗氧化性比较

采用邻二氮菲-Fe²⁺氧化法,邻苯三酚自氧化法以及卵黄脂蛋白不饱和脂肪酸（PUFA）过氧化体系,对甘青铁线莲花乙醚提取物、甲醇提取物、乙醇提取物和槲皮素的抗氧化活性进行测定和比较。结果表明,甘青铁线莲花不同溶剂提取物对不同的自由基清除作用差异较大。与槲皮素相比较,各提取物对超氧阴离子自由基（·O₂^-）清除的强弱为:槲皮素>乙醚提取物>乙醇提取物>甲醇提取物。对于羟基自由基（·OH）的清除能力乙醚提取物优于其他2种提取物,但低于槲皮素,对抑制卵黄脂蛋白脂质过氧化（LPO）作用的大小依次为乙醇提取物>槲皮素>乙醚提取物>甲醇提取物。因此,不同溶剂的提取物均具有一定的抗氧化性,其中乙醚提取物对几种自由基的清除作用相对较好,三种提取物对脂质过氧化物作用抑制最强,可以作为潜在的天然抗氧化剂开发利用。     

冷等离子体强化制备金属催化剂研究进展

冷等离子体属于非热平衡等离子体,具有较高的电子能量和较低的气体温度,是一种制备金属催化剂的绿色新方法.等离子体强化制备金属催化剂包含复杂的物理和化学多相反应.一方面,等离子体提供的高活性环境不但可以加速化学反应,使反应时间从数小时缩短至数分钟,还可以使热力学或者动力学上不可行的反应发生,实现非常规制备;另一方面,等离子体强化制备过程中,在介观尺度上等离子体对相接触行为的影响,可使获得的金属催化剂结构区别于传统方法制备的催化剂.本综述总结了冷等离子体制备金属催化剂的反应器结构、物理化学机理、获得金属催化剂的结构特性、制备面临的挑战,并对未来发展进行了展望.重点阐述了冷等离子体反应器、制备机制及其对金属催化剂结构和性能的影响.     

Ultrasonic role to activate persulfate/chlorite with foamed zero-valent-iron: Sonochemical applications and induced mechanisms

The novel system, consisting of composite oxidants (persulfate/chlorite, S₂O₈²⁻/ClO₂⁻) and stationary phase activator (zero-valent-iron foam, Fe⁰_f) driven by ultrasonic (US) field, was applied to treat the triphenylmethane derivative effectively even at low temperature (≈ 289 K). By comparisons of sub-systems, the US roles to S₂O₈²⁻, ClO₂⁻, and Fe⁰_f were seriatim analyzed. US made the reaction order of multi-component system tend to within 1 (leading to de-order reaction), and widened pH activating range of the Fe⁰_f by sonicate-polishing during the process of ClO₂⁻ co-activating S₂O₈²⁻. US and Fe⁰_f were affected by fluid eddy on activating S₂O₈²⁻/ClO₂⁻. The Fe⁰_f had slight effect on the temperature of US bubble-water interface but the addition of ClO₂⁻ lowered it. The partitioning capacity of the above US reactive zone increased during the reaction. US and ClO₂⁻ could enrich the kinds of degradation intermediates. The contributions of free radicals (ClO_x-based radicals, sulfate radicals (SO₄⁻), and hydroxyl radicals (OH)) and non-free radicals (ClO₂, and O = Fe^IV/V from ionic Fe under “-O-O-” of S₂O₈²⁻ and cyclic adjustment reaction of ClO₂⁻) processes by sonochemical induction were equally important by corresponding detection means. Especially, real-time and online high-resolution mass spectrum by self-developing further confirmed the chain transfers of different free radicals due to US role. The findings expanded the application of sono-persulfate-based systems and improved understanding on activation mechanism.     

Effect of glutaphen on generation of active oxygen species, photosynthetic electron transport, and the functional activity of photosystem 2 in Chlorella cells

Treatment of chlorella green algae (Chlorella sp.) for 2 h in the dark with the photodynamic herbicide glutaphen (GTP), consisting of 0.3 mM 1,10-phenanthroline and 0.6 mM glutamic acid, followed by illumination leads to efficient generation of active oxygen species (AOS). After 15 min of illumination, AOS accumulation reaches 200% compared with the level in cells of the control culture, then it decreases down to 130% and 115% after 1 day and 3 days of illumination. During the first few days after treatment, we observe inhibition of synthesis of a specific precursor of chlorophyll (Chl): 5-aminolevulinic acid molecules, and then we observe stimulation of the synthesis. The effect of GTP on the photosynthetic activity of chlorella does not depend on the AOS level but rather remains uniform, in contrast to its effect on the Chl biosynthesis system. GTP does not change the efficiency of light harvesting and charge separation at the reaction centers of photosystem (PS) 2, but significantly lowers the functional efficiency of the electron transport chain: the photochemical quenching constants for Chl a fluorescence and the effective quantum yield of photochemical reactions in photosystem 2 decrease. The major mechanism of action for GTP is probably displacement of the secondary quinone acceptor Q_B from its binding site on the D1 protein by the 1,10-phenanthroline, consequent inhibition of electron efflux from Q _A ⁻ and increase in the fraction of Q_B-nonreducing centers of PS 2. The active oxygen species generated in the cells have a photodegradative effect on the Chl biosynthesis system, in particular on its initial steps, and do not involve already formed pigment-protein complexes of PS 2. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 801–806, November–December, 2006.     

氮直流辉光放电活性粒子(N~+,N)的产生率

在氮直流辉光放电等离子体中采用快电子和离子(N+2,N+)混合的蒙特卡罗模型,模拟研究了e+N2→N+ N+N+2e e和N+2+N2→N++N+N2过程中粒子(N+,N)产生率的轴向分布随放电参数(工作气压、放电电压和温度)的变化规律。结果表明:两种离解过程中氮活性粒子(N+,N)的产生率都随气压和电压的增加而增大,随放电气体温度的升高而降低;但N+2-N2离解碰撞主要发生在阴极附近。电压较高时,阴极处的离子N+主要由N+2-N2离解过程产生;电压较低时,N+2-N2离解过程可忽略。中性原子N主要由电子碰撞离解过程产生。     

ELECTRON TRANSPORT BEHAVIOURS IN THE NITROGEN DIRECT CURRENT GLOW DISCHARGE

A Monte Carlo simulation is presented to describe the electron transport behaviours in the nitrogen direct current glow discharge. The energy and angular distributions of the electrons at different positions of the cathode dark space are calculated; their energy and density distribution features throughout the entire discharge are discussed. The influence of molecular vibrational excitation, typical for electron－molecule collisions, has been studied and the elementary process of active species generation has been illustrated. The simulated results reveal that, in the cathode dark space, the high-energy electrons are mainly forward scattering and behave as a high-energy ‘electron beam'. The sharp increase of the number of secondary electrons plays an important role in producing active species at the interface between the cathode dark space and the negative glow region. The vibrational excitation enhances the energy loss of electrons in the negative glow region.     

A Highly Effective,Stable Oxygen Evolution Catalyst Derived from Transition Metal Selenides and Phosphides

Recently, transition metal chalcogenides and phosphides have been increasingly reported as efficient and stable oxygen evolution reaction (OER) catalysts in alkaline medium, despite the fact that they are thermodynamically unstable under highly oxidative potentials. Here the active forms of these materials are elucidated by synthesizing a hybrid catalyst, which has a metal chalcogenide in the form of CoSe₂ and metal phosphide in the form of CoP—CoSe₂|CoP. Both CoSe₂ and CoP in the as‐prepared catalyst are completely transformed into their respective oxyhydroxides and hydroxides, which are, in fact, the true OER‐active species in alkaline medium and not the selenide and phosphide themselves. The derived oxides from the hybrid catalyst deliver an excellent OER activity by reaching a current density of 10 mA cm⁻² at a low overpotential of 240 mV (vs reversible hydrogen electrode (RHE)) and a Tafel slope of 46.6 mV dec⁻¹. The stability of the derived oxyhydroxide/hydroxide catalyst shows no appreciable deactivation during 120 h of continuous electrolysis, displaying an extraordinary operational stability.     

稀土改性的氧化镍基低温乙烷氧化脱氢催化剂活性氧物种的Raman光谱研究

利用共沉淀法制备了几种稀土金属氧化物改性的氧化镍催化剂 ,考察了其乙烷氧化脱氢 (ODE)制乙烯的催化性能 ,讨论了不同稀土金属氧化物掺杂浓度对催化剂催化性能的影响 ,利用Raman光谱技术初步表征反应在该类催化剂上的活性氧物种为Raman谱带出现在 1 0 60cm- 1 的表面双原子超氧物种O-2 ,该谱峰的大小与催化剂的ODE性能有很好的对应关系。     

活力物质的非平衡结构和动力学

活力物质是一类典型的非平衡态体系,已成为软凝聚态物理新近发展的一个重要研究方向.活力物质由微驱动粒子组成,驱动力独立地施加在体系中的每个粒子上.文章概述了作者平时研究中所关注的一些活力物质系统中出现的十分有意义的现象,着重介绍了活力物质系统的构成,以及活力物质的气液态、铁磁态、向列相态和凝胶状态中涌现出的非平衡结构及其特殊的动力学行为.     

基于“猫眼”效应的激光侦察技术及其在军事上的应用

光电设备或光学观瞄设备的光学窗口对入射激光具有较强的反射特性,该特性也被称为"猫眼"效应。从理论上分析了猫眼效应产生的机理,并将理论计算结果与实验结果进行了比较。论述了基于猫眼效应的激光侦察技术原理和该技术在军事上的应用。讨论了影响猫眼效应的因素,并用实验结果证明了理论分析得出的部分结论。     

Stochastic Hydrodynamics of Complex Fluids: Discretisation and Entropy Production

Many complex fluids can be described by continuum hydrodynamic field equations, to which noise must be added in order to capture thermal fluctuations. In almost all cases, the resulting coarse-grained stochastic partial differential equations carry a short-scale cutoff, which is also reflected in numerical discretisation schemes. We draw together our recent findings concerning the construction of such schemes and the interpretation of their continuum limits, focusing, for simplicity, on models with a purely diffusive scalar field, such as ‘Model B’ which describes phase separation in binary fluid mixtures. We address the requirement that the steady-state entropy production rate (EPR) must vanish for any stochastic hydrodynamic model in a thermal equilibrium. Only if this is achieved can the given discretisation scheme be relied upon to correctly calculate the nonvanishing EPR for ‘active field theories’ in which new terms are deliberately added to the fluctuating hydrodynamic equations that break detailed balance. To compute the correct probabilities of forward and time-reversed paths (whose ratio determines the EPR), we must make a careful treatment of so-called ‘spurious drift’ and other closely related terms that depend on the discretisation scheme. We show that such subtleties can arise not only in the temporal discretisation (as is well documented for stochastic ODEs with multiplicative noise) but also from spatial discretisation, even when noise is additive, as most active field theories assume. We then review how such noise can become multiplicative via off-diagonal couplings to additional fields that thermodynamically encode the underlying chemical processes responsible for activity. In this case, the spurious drift terms need careful accounting, not just to evaluate correctly the EPR but also to numerically implement the Langevin dynamics itself.