Dynamics of electric activities in neuron and neurons of network induced by autapses

The effect of autapse on adjusting the membrane of potentials of neuron is described by imposing a time-delayed feedback on the membrane of neuron in a close loop type,and the Hindmarsh-Rose(HR)neuron under autapse is investigated.Firstly,the electric activity of single HR neuron under electric autapse and chemical autapse is investigated.It is found that quiescent neuron is activated due to appropriate time delay and feedback gain in the autapse,and the autapse plays an important role in waking up neuron.The parameter region for periodic,chaotic activity of neuron under autapse is calculated in a numerical way,and transition from spiking to bursting is observed by increasing the feedback gain and time delay carefully.Furthermore,the collective electric activities of neurons in a ring network is investigated and abundant electric activities are observed due to the competition between the autapse and the time-delayed coupling between adjacent neurons in the network,and time delay in coupling between neurons also plays an important role in enhancing synchronization in the network.     

电场对化学沉降制备的硫化镉纳米颗粒的影响

首次把外加电场作为环境因素,引入到在均匀溶液中化学沉降法制备的硫化镉纳米颗粒。用粉末X射线衍射(XRD)观察到,电场对化学沉降方式制备的硫化镉纳米颗粒生长方式的影响。用透射电子显微镜(TEM)观察到,外加电场显著地影响了获得纳米颗粒的形貌。外加静电场成为一种能够影响纳米颗粒在溶液中生长的新手段。     

核盘菌和草酸诱导下的油菜几种酶活力的变化分析

油菜菌核病是油菜生产中的重要病害之一,为了进一步探讨菌核病的致病机理和抗病机制,采用草酸浸叶和接种核盘菌菌丝两种方法分别处理甘蓝型油菜叶片,确定草酸最佳浓度为3 mmol/L,分析叶片中过多酚氧化酶(PPO)、氧化物酶(POD)、纤维素酶和几丁质酶的活力变化,发现草酸和核盘菌都可以诱导防御酶PPO和POD活力升高,可增...     

肉苁蓉属化学成分及生物活性研究进展

肉苁蓉为传统补益类中药,近年来被研究发现具有广泛的生物活性作用。参考近30年国内外相关文献,综述了肉苁蓉的化学成分及生物活性。肉苁蓉属含有苯苷类(苯乙醇苷类、苯甲醇苷类)、环烯醚萜及其苷类、木质素及其苷类等,具有神经保护、抗疲劳、防治脑缺血及脑缺血再灌注损伤等作用;其中,苯乙醇苷类作为肉苁蓉中的主要活性物质在神经保护作用中起主导作用。     

体外抗坏血酸诱导中脑源神经干细胞向多巴胺能神经元的分化

为探索抗坏血酸(ascorbic acid,AA)对小鼠胚中脑区来源的神经干细胞向多巴胺能神经元诱导分化的影响,本研究于体外培养小鼠胚中脑区来源的神经干细胞,传代纯化并分为四组,在有血清条件下分别给予10 μM、100 μM、200 μM AA诱导分化,并设空白组对照,DAPI细胞核标记,抗酪氨酸羟化酶免疫荧光细胞化学技术鉴定分化结果,荧光显微镜下计数阳性细胞比例.结果显示:在本诱导分化实验中,AA作用下中脑神经干细胞分化出多巴胺能神经元比例最高约为9%,明显高于空白对照组(约1%,P＜0.01).     

Effect of electric field on the activity and quenching structure of liquid Cu-Al alloys

The activity coefficient of A1 in molten Cu decreases with the increasing of electric current applied to the liquid alloy of Cu-0.2wt%Al. To investigate the mechanism, the quenching experimental results of the liquid A1-Cu alloy show that there is a remarkable change in structure, in which the solute congregates along the current direction especially for DC current. The mechanism of the activity coefficient change of A1 in molten Cu-0.2wt%Al alloy treated by electrical field was discussed. Further, the results also provide an evidence for the short-range-ordered liquid metal.     

Electrical activities of neural systems exposed to sinusoidal induced electric field with random phase

The brain neural system is often disturbed by electromagnetic and noise environments, and research on dynamic response of its interaction has received extensive attention. This paper investigates electrical activity of Morris-Lecar neural systems exposed to sinusoidal induced electric field(IEF) with random phase generated by electromagnetic effect. By introducing a membrane depolarization model under the effect of random IEF, transition state of firing patterns, including mixed-mode oscillations(MMOs) with layered inter-spike intervals(ISI) and intermittency with a power law distribution in probability density function of ISI, is obtained in a single neuron. Considering the synergistic effects of frequency and noise, coherence resonance is performed by phase noise of IEF under certain parameter conditions. For the neural network without any internal coupling, we demonstrate that synchronous oscillations can be induced by IEF coupling, and suppression of synchronous spiking is achieved effectively by phase noise of IEF. Results of the study enrich the dynamical response to electromagnetic induction and provide insights into mechanisms of noise affecting information coding and transmission in neural systems.     

化学修饰对寡核苷酸生物活性的影响

寡核苷酸可根据碱基互补原则特异性地与靶基因或mRNA结合。从基因复制,转录,mRNA剪接,转运或转译等水平上抑制目的基因的表达,从而实现基因调控,其生物功能在很大程度上取决于它的稳定性,生物利用度及靶基因结合或反应的特性,通过特定的化学修饰可改变寡核苷酸的物理,化学特性,其中利用一些活性基团－DNA嵌入剂与寡核苷酸偶联修饰是非常重要和行之有效的修饰方法,能有效地提高寡核苷酸的生物功能。     

Preparation and characterization of calcium aluminate by chemical synthesis

Saturated Ca（OH）2 and AlCl3 solutions were used to synthesize calcium aluminate hydrate precipitates at room temperature; high purity calcium aluminate powders with stable phases were made by calcination of the precursors at a temperature as low as 1100℃. PSD and BET analysis revealed the particles with sizes ranging from submicrometer to several micrometers and with a specific area of 13 m^2/g. The measurement of hydraulic exotherm revealed that the exothennal rate is in peak for about 2 h. The exothermal quantities are 449.24 J/g at 12 h and 488.38 J/g at 24 h. Its strength development is quick and the 1 day curing strength is almost equal to 100% of the 3 days curing strength in the mortar test.     

电力用户与电能质量的关系

通过对电能质量(频率、电压、谐波及三相不平衡度)的概念、影响因素、偏离标准的危害及应采取的措施等几方面的分析,阐明了电能质量不仅是电力管理部门的事情,发配电与用户之间存在着非常紧密的相互制约的关系.需共同努力,创造条件,将电网电能质量的指标确定在综合优化的范围内.     

高压脉冲电场(PEF)对溶菌酶抑菌活性的影响

研究了不同脉场强度和脉冲数对溶菌酶抑菌能力的影响。结果表明,随着脉冲强度的增加,溶菌酶抑菌能力呈波浪式变化,在25 kV/cm时,抑菌能力达到最大值,比对照组提高了10.6%。PEF处理后溶菌酶液放置于4℃下贮藏1 h和10 h后,溶菌酶抑菌能力都有增加,变化规律和PEF处理后直接测得的结果相似,而随着贮藏时间的延长溶菌酶的抑菌能力又有下降趋势。在设定的脉冲数内,脉冲数的变化对溶菌酶抑菌能力的影响不显著。荧光分析表明,25 kV/cm下相对荧光强度最大,比对照组提高了15.42%;但贮藏一段时间后相对荧光强度有下降的趋势。在设定的脉冲数内,脉冲数的变化对溶菌酶的相对荧光强度影响不显著。     

Reactivity of Tourmaline by Quantum Chemical Calculations

ZnAb initio calculations on reactivity of tourmaline were performed using both Gaussian and density function theory discrete variation method （DFT-DVM）. The HF, B3LYP methods and basis sets STO-3G（3d,3p）,6-31G（3d,3p） and 6-311＋＋G（3df,3pd） were used in the calculations. The experimental results show energy value obtained from B3LYP and 6-31＋＋1G（3df,3pd） basis sets is more accurate than those from other methods. The highest occupied molecular orbital （HOMO） of the tourmaline cluster mainly consists of O atom of hydroxyl group with relative higher energy level, suggesting that chemical bond between those of electron acceptor and this site may readily form, indicating the higher reactivity of hydroxyl group. The lowest unoccupied molecular orbital （LUMO） of the tourmaline cluster are dominantly composed of Si, O of tetrahedron and Na with relative lower energy level, suggesting that these atoms may tend to form chemical bond with those of electron donor. The results also prove that the O atoms of the tourmaline cluster have stronger reactivity than other atoms.     

加电固定化膜式反应器生产L—丙氨酸

选用突变株菌,利用加电固定化细胞膜式反应器生产Ｌ－丙氨酸,旨在消除产物Ｌ－丙氨酸对Ｌ－天冬氨酸－β－脱羧酶的竞争性抑制。研究结果表明,加静电优于通电流;随着静电压的加大,表观米氏常数Ｋｍ‘变小,说明该反应器的使用一定程度地解除了产物的抑制;     

电气化铁路接触网雷电感应过电压计算及其闪络概率研究

我国电气化铁路牵引网额定工作电压为27.5 kV,其绝缘水平与电力系统35 kV配网架空线路相当,因此对其开展雷害研究必须考虑雷电感应过电压。在建立接触网架空线路、钢轨和接触网支柱模型的基础上,基于Agrawal场线耦合模型对接触网线路的雷电感应过电压进行了仿真研究,并结合电气几何模型对接触网感应雷击闪络概率进行了计算。     

物理/化学共交联水凝胶的溶胀性能

以物理交联剂锂皂石（hectorite）和化学交联剂亚甲基双丙烯酰胺（MBA）共同作为交联剂,在水溶液中通过自由基聚合制备聚异丙基丙烯酰胺水凝胶,并采用称重法研究了水凝胶的（消）溶胀和刺激响应性行为．结果表明,所得水凝胶的溶胀度介于分别以hectorite和MBA制备的水凝胶之间,消溶胀度变化曲线和MBA交联水凝胶相近,在20℃和40℃交替刺激下表现出良好的溶胀一消溶胀行为．     

化学沉淀-磁絮凝深度快速除磷的研究

采用化学沉淀法研究Al2（SO4）3、FeCl3、CaCl2的药剂用量和pH值对除磷效果的影响,探讨非磁性悬浮物磁性接种的机理,并分析了铝、铁、钙的磷酸盐沉淀物由于加入磁种而变得易于沉降,特别是在磁场力作用下沉降速度加快的原因。结果表明,Al2（SO4）3、FeCl3、CaCl2是磷酸根离子的有效沉淀剂,在适当的药剂投加量和pH值条件下,废水经过处理后,剩余磷的浓度小于0．5mg／L;生成的铝、铁、钙的磷酸盐沉淀物颗粒与Fe3O4颗粒在某一pH值下表面电性相反,易发生相互凝聚;磁性接种的铝、铁、钙的磷酸盐沉淀物不仅变得更重,而且在磁场中还受到与重力方向相同的磁场力作用。     

射频感应耦合等离子体模式转变的发射光谱

通过改变气体流率、放电气压和气体组成,研究射频感应耦合放电等离子体(inductively coupled plasma,ICP)在圆柱型放电装置中E模到H模的转化规律.采用发射光谱诊断法,对419.8 nm氩原子谱线和434.8 nm氩离子谱线进行采集和分析,以表征E模到H模的转换功率.当放电气压为60 Pa时,E-H转换功率最小;在Ar中加入He对E-H转换功率几乎没有影响,而加入N2后,E-H转换功率发生了明显的改变;随着氩气流率的增加,E-H转换功率在不断减小.结果表明:射频感应耦合放电等离子体E模到H模的转化是一个突然变化的过程,转换功率会因不同的气体流率、放电气压和气体组成而变化.     

用变n次抛物线叠加敷设缓和曲线

按汽车转向时的实际特性分析了公路缓和曲线应满足的理论关系，并采用了变ｎ次抛物线在切线上和圆弧上分别叠加，从而使所敷设的缓和曲线更简化，更附合实际。     

利用STN进行化学化工文献检索

概括介绍了STN检索系统,提出利用STN俭索化学化工文献的原则、途径和方法,给出检索实 例并列出STN系统的其它代表性化学化工数据库.     

基于十钒酸阴离子和过渡/碱金属水合阳离子的超分子组合体构建

通过水热法制备出5种钒氧多酸簇合物,[K6（H2O）10][V10O28]（1）,[Na2A4（H2O）10][V10O28][A=K（2）,Cs（3）],[K2B2（H2O）16][V10O28][B=Co（4）,Ni（5）],X射线衍射分析显示,它们均由[V10O28]6-簇阴离子和过渡/碱金属水合阳离子所组成,通过金属-氧键的相互作用,阴离子和阳离子构建了化合物1～3的三维立体框架结构和化合物4,5的二维层状网状结构。