自旋标记荧光探针表征生物活性分子的自由基损伤

生命过程中产生的经基自由基(^˙OH)已引起广泛关注.目前,对于^˙OH的研究主要集中在直接对^˙OH进行定量表征^[1~3]和问接检测^˙OH诱导损伤生物大分了的损伤产物.^˙OH诱导损伤生物大分了,能够产生大量的碳中心自由基^[4,5].     

高等植物叶绿体中光诱导生成NO的ESR证据

NO分子在生物细胞体系中是一个十分重要的信使分子,它具有调节细胞凋亡、松弛平滑肌、抑制血小板聚集与黏附、抑制病原体和肿瘤生长等多种生理功能^[1,2],因而备受生物学家的关注.众所周知,动物细胞中NO主要来源于一氧化氮合酶(NOS)的表达^[3];然而,直到最近才有研究证明植物细胞中存在参与调节植物生长和激素信号转导的NOS基因^[4].一般认为植物细胞中NO主要来源于硝酸盐还原酶(NR)^[5].我们曾在高等植物光系统中研究发现了与电子传递相关的活性氧生成机制^[6～8],但其间是否也会通过光诱导电子传递产生NO尚不清楚.Kozlov等^[9]曾报道在小鼠线粒体内存在与亚硝酸盐还原酶功能类似的还原型烟酰胺腺嘌呤二核苷酸(NADH)诱导电子传递生成NO的反应,本文采用电子自旋共振(ESR)方法验证了高等植物叶绿体内光诱导电子传递可产生NO的设想.     

细胞内钙离子体系中的双参数内信号随机共振

自从Benzi等于1981年提出随机共振(SR)现象以来,它已经受到物理、化学和生物学等领域的关注．SR是非线性体系中弱外信号和环境扰动之间的协同作用．后来胡岗等发现外信号可以由体系的内信号所代替,此时出现的SR被称为内随机共振(ISR)．通常对SR的研究都集中在外信号和噪音扰动参数上,如电压、电流和压力等．     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

不饱和格氏试剂与不饱和酯的共轭加成 Ⅳ.乙烯四羧酸四乙酯与烯烃基溴化镁的加成作用

邢其毅等^[1]研究了烷基、芳基格氏试剂对乙烯四羧酸四乙酯的加成,发现这类反应为1,4-加成^[2~6].     

三苯基膦：转换硫醇保护的纳米粒子成[Au25(PPh3)10(SR)5Cl2]2+

我们在此报道了一种未曾发现的有趣现象：尽管[Au₂₃(SC₆H₁₁)₁₆]⁻、Au₂₄(SC₂H₄Ph)₂₀ (Ph:苯环)、Au₃₆(TBBT)₂₈ (TBBTH:对叔丁基苯硫酚)、Au₃₈(SC₂H₄Ph)₂₄、混合Au_x(SC₂H₄Ph)_y团簇及3 nm的金纳米粒子有不同的组成、结构、尺寸和保护性硫醇配体,但它们在三苯基膦(PPh₃)作用下,均能统一地经由亚稳的[Au₁₁(PPh₃)₈Cl₂]²⁺最终转化为稳定的双二十面体[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺ (SR:硫醇配体)。换句话说,三苯基膦是这些硫醇保护的纳米粒子的统一转化器。然而,聚乙烯吡咯烷酮(PVP)/柠檬酸盐(Citrate)保护的金纳米粒子和[Ag₂₅(SPhMe₂)₁₈]⁻ (Me:甲基)在同样的条件下,却不能转化为[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺或[Ag₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺,暗示了硫醇保护的金纳米粒子具有与三苯基膦反应的独特性能。另外,我们考察了配体对双二十面体[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺团簇荧光性能的影响。     

一系列Ru(II)配合物电致化学发光性质的比较研究

比较研究了以C₂O₄^2－为共反应物时5个结构相关的Ru(II)配合物[Ru(bpy)₂L¹]^2＋, [Ru(bpy)₂L²]^2＋, [Ru(bpy)₂L³]^2＋, [Ru(phen)₂L¹]^2＋和[Ru(phen)₂L²]^2＋(其中bpy＝2,2′-联吡啶, phen＝1,10-邻菲啰啉, L¹＝4-羧基苯基咪唑[4,5-f][1,10]邻菲啰啉, L²＝3-羧基-4-羟基苯基咪唑[4,5-f][1,10]邻菲啰啉, L³＝3,4-二羟基苯基咪唑[4,5-f][1,10]邻菲啰啉)的电致化学发光(ECL)性质. 结果表明, 酚羟基的存在能有效地淬灭Ru(II)配合物[Ru(bpy)₂L²]^2＋, [Ru(bpy)₂L³]^2＋和[Ru(phen)₂L²]^2＋的ECL, 其它Ru(II)配合物的ECL量子效率与[Ru(bpy)₃]^2＋相差不大.     

芯片式流通池顺序注射化学发光法测定水中的亚硝酸根

微流控芯片(Microfluidic chips)是微全分析系统(μTAS)研究中最为活跃的领域,在仪器微型化方面展现出很多的优点^[1].化学发光由于其自身的特性在微芯片检测中应用逐渐增多^[2,3].     

直接脱碳酸化制备有机离子插层的层状双氢氧化物

层状双氢氧化物(Layered double hydroxide, LDH)是一种具有阴离子可交换性质的层状无机材料, 由于其具有多种功能性质, 已被广泛应用于催化^[1~3]、酸吸附剂^[4]、传感器^[5]及聚合物填料^[6~8]等领域. 传统的共沉淀法制备的LDH结晶度低、尺寸小(直径通常小于100 nm). 1998年, Costantino等^[9]采用均匀沉淀法制备出了高结晶度、大尺寸(微米量级)且层间具有CO₃^2-的LDH(LDH-CO₃), 引起了人们的极大兴趣. 为解决LDH-CO₃难于交换和剥离的难题, Iyi等^[10,11]采用两步法制备了层间具有NO₃^- 或有机阴离子的LDH, 即首先采用 HCl-NaCl混合溶液将LDH-CO₃转化成为LDH-Cl, 然后再采用过量的阴离子进行交换制备LDH-NO₃或有机阴离子插层的LDH.     

吸收液采样-高效液相色谱法测定室内空气中甲醛的含量

<正>甲醛是一种无色有刺激性气味的气体，被世界卫生组织(WHO)定为致畸和致癌的物质之一^[1]。我国规定室内空气甲醛的限值为0.10 mg·m-3^[2]。目前监测环境中甲醛的国家标准测定方法很多^[3],常用的有4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂(Ⅰ)(AHMT)分光光度法^[4]、3-甲基-2-苯并噻唑啉酮腙盐酸盐水合物(MBTH)酚试剂分光光度法^[5]、乙酰丙酮分光光度法^[6]、气相色谱法(GC)^[7]、     

Signal transduction in a coupled hormone system: selective explicit internal signal stochastic resonance and its control

Cooperative interactions of signal transduction and environmental noise are investigated with a coupled hormone system, in which selective explicit internal signal stochastic resonance (EISSR) is observed. More specifically, the large peak of a period-2 oscillation (i.e., a strong signal) is greatly amplified by the environmental noise while the small peak (i.e., a weak signal) does not exhibit cooperative interactions with noise. The EISSR phenomenon could be controlled by adjusting the frequency or amplitude of an external signal and a critical amplitude for external signal is found. Significantly, the maximal signal-to-noise ratio increases almost linearly with the increment of control parameter, despite that the magnitude of the large peak is decreased. In addition, the noise does not alter the fundamental frequencies of the strong signal and the weak signal, which implicates that the system can keep its intrinsic oscillatory state and resist the effect of environmental fluctuations.     

细胞体系中内噪声对弱信号检测的积极作用

在小尺度的生物化学反应体系中内噪声是普遍存在的,本文采用化学Langevin方程研究了细胞体系中内噪声对弱信号检测的作用. 研究发现, 在Hopf分岔点附近, 当弱信号非常小以至于不能独立地激发细胞内的钙尖峰振荡时, 内噪声能够帮助细胞内的钙振荡信号越过一个域值, 并且在一个最佳的内噪声强度下, 内噪声、内噪声诱导的钙振荡和弱信号之间会产生共振现象, 由此极大地增强了细胞体系对弱信号的检测能力. 由于内噪声是通过细胞尺度变化而改变的, 因此这种现象也说明了在对弱信号检测行为中最佳细胞尺度的存在. 研究还发现最佳的细胞尺度与真正的细胞体积是相吻合的, 并且基本不随外界刺激的改变而改变, 这具有重要的生物学意义.     

Constructive Role of Internal Noise for the Detection of Weak Signal in Cell System

Taking into account the existence of internal noise in small scale biochemical reaction systems, we studied how the internal noise would influence the detection of weak external signal in the cell system using chemical Langevin equation. The weak signal was too small to, separately, fire calcium spikes for the cell. We found that, near the Hopf bifurcation point, the internal noise could help the calcium oscillation signal cross a threshold value, and at an optimal internal noise level, a resonance occurred among the internal noise, the internal noise-induced calcium oscillations, and the weak signal, so as to enhance intensively the ability of the cell system to detect the weak signal. Since the internal noise was changed via the cell size, this phenomenon demonstrated the existence of an optimal cell size for the signal detection. Interestingly, it was found that the optimal size matched well with the real cell size, which was robust to external stimulus, this was of significant biological meaning.     

随机扰动和周期信号对基因调控系统的影响

采用数值模拟方法,研究了生物信息学中人类遗传因子——基因的转录调控系统.研究表明:噪音对该系统的影响作用,体系可以出现内随机共振现象和噪音诱导的"开-关"过程;当周期信号加到系统上时,信号振幅和频率的改变能够使细胞信号产生更为丰富的动力学行为,如周期共振现象.     

阳极溶解电化学振荡体系中白噪声诱导随机共振的模拟

通过对电化学阳极溶解振荡模型加白噪声后引发的随机共振现象的模拟研究发现,在该体系的周期二振荡态时呈现显性内信号随机共振现象。当白噪声加在该电化学体系的周期二振荡态时,内信号的信噪比随着噪声的增大达到了最大值。同样噪声强度情况下,强信号的信噪比增加比弱信号的增加更加迅速。如果同时改变噪声强度,体系的信号频率也维持不变。研究表明,噪声对内信号的优化具有选择性,而体系的内信号也具有抵抗噪声和维持内在机制不变的性质。     

Colored non-gaussian noise driven open systems: generalization of Kramers' theory with a unified approach

In this paper we have calculated escape rate from a meta stable state in the presence of both colored internal thermal and external nonthermal noises. For the internal noise we have considered usual gaussian distribution but the external noise may be gaussian or non-gaussian in characteristic. The calculated rate is valid for low noise strength of non-gaussian noise such that an effective gaussian approximation of non-gaussian noise wherein the higher order even cumulants of order "4" and higher are neglected. The rate expression we derived here reduces to the known results of the literature, as well as for purely external noise driven activated rate process. The latter exhibits how the rate changes if one switches from non-gaussian to gaussian character of the external noise.     

自催化三分子模型内噪声随机共振

The stochastic resonance in chemical reaction systems has recently attracted growing attentions. Using chemical Langevin equation,the effect of internal noise has been studied on the dynamical behavior of a single and a one-way coupled cubic autocatalator. For the single system,it is found that the internal noise can induce sustained oscillations,and the signal-to-noise ratio（SNR）undergoes a maximum with the variation of the system size. For the coupled system,the SNR passes through a maximum with changing coupling strengths as well as with changing system sizes,which demonstrates the occurrence of the internal noise stochastic resonance（INSR）and optimal size effect. In the presence or absence of influx into the system,the coupling enhanced or suppressed INSR is found in the coupled system. All cells of the coupled system appear to exhibit INSR at an approximately equal size at a suitable coupling strength,implying that the optimal system size and coupling strength can make the system reach an optimal chemical reaction state.     

Colored noise-enhanced intrinsic stochastic oscillations in CO oxidation on nanometer-sized Pd particles

How colored Gaussian noise (CN) affects the intrinsic stochastic oscillations (ISO) of CO oxidation on a nm-sized Pd particle is studied. It is found that the optimal ISO can be enhanced not only by a CN with appropriate noise intensity, but by a CN with appropriate correlation times. Moreover, the optimal ISO can be most greatly enhanced by the CN when the noise intensity or the correlation time is optimal. This result shows that external noise may, via its interplay with the internal noise of the system, play a constructive role in the ISO of the system, and the ISO can employ the external noise to reach a best oscillation performance. Supported by the Science Foundation of Ludong University (23140301, L20072805)     

介观振荡化学反应体系的内噪声随机共振

用化学Langevin方程研究了内噪声对介观振荡化学反应体系的影响.研究发现,在确定性体系处于定态条件下,内噪声可以导致体系振荡:随着内噪声强度的变化,诱导振荡信号的信噪比通过一个极大值,表明内噪声随机共振的出现;由于内噪声强度随着系统体积的变化而改变,因此,这一现象也证明了系统尺度共振,即最佳尺度效应的存在.     

低频外信号选择性优化的钙信号与IP3信号

用数值模拟的方法研究了钙信号系统中钙振荡与IP3振荡共存时,噪音和低频外信号对它们的选择性优化和调控.研究结果显示,低频外信号能够协同噪音作用,在一定强度范围内优化钙信号和IP3信号,但能够协同优化钙信号的条件范围明显较宽,说明协同作用对钙信号具有优先选择性.此外,在两种化学信号均可以被优化的外信号参数作用下,信号被优化的噪音强度范围也具有选择性.