最小神经元模型放电起始动态控制与分析

本文采用最小神经元模型,从生理学角度设计wash-out滤波器,实现了不同放电起始动态机理之间的转换,并证明wash-out滤波器控制通过影响阈下电流的竞争结果改变了神经元的放电起始动态机理. 关键词： 放电起始动态机理 阈下电流竞争 最小神经元模型 wash-out滤波器     

基于复杂度的针刺脑电信号特征提取

为探究针灸刺激对大脑活动产生的影响,文章设计了4种针刺频率针刺右腿足三里穴获取脑电的实验.首次采用排序递归图和关联维数方法提取针刺脑电信号的复杂度参数来反映针刺大脑的功能状态,并基于这些方法研究了针刺作用对大脑功能区域的影响以及不同针刺频率与脑电复杂度的相关性.发现针刺时脑电的复杂度高于针刺前,尤以频率为100次/min的针刺影响最为明显;从FP2, F7, T3导联脑电中提取的确定性指标(DET)可作为区分针刺状态与针刺前状态的一种特征参数. 关键词： 针灸 脑电 排序递归图 关联维数     

Au／TS-1@Mesosilica双功能催化材料的制备及其催化丙烯直接环氧化性能

设计制备了一种新型微孔介孔复合核壳结构钛硅分子筛TS-1@Mesosilica（TS-l@Ms）,核为MFI结构钛硅分子筛TS-1,壳层为以非离子表面活性剂P123为模板剂组装形成的介孔氧化硅．壳层氧化硅具有三维蠕虫状孔道结构,有利于微孔和介孔部分的连通及反应物和产物的扩散．通过沉积沉淀法将金纳米粒子负载在壳层介孔孔道,和TS-1中的钛活性中心协同,形成适合于C3H6和H2、O2直接气相环氧化制备环氧丙烷（PO）的双功能催化材料．实验结果表明,Au／TS-1@MS在空速8000mLg-h、温度473K条件下连续反应132h,活性和选择性没有明显下降,丙烯转化率保持在3．7％左右,PO选择性87％以上．     

晶体相场方法模拟纳米晶生长过程

双模的PFC模型能够很好地模拟纳米晶的晶粒长大,可以在二维平面显示出不同晶面类型的晶粒长大过程、不同错配度和晶粒取向的晶界结构,还可以模拟出准共格晶界,观察到晶界处由于错配度不同引起的位错结构。这些模拟得到的结果,对实现人工控制纳米晶晶界结构,指导实验设计具有新型纳米晶界的结构材料具有重要意义。     

Modulation of electroencephalograph activities by manual acupuncture stimulation in healthy subjects: An autoregressive spectral analysis

To investigate whether and how manual acupuncture (MA) modulates brain activities, we design an experiment that acupuncture at acupoint ST36 of right leg to obtain electroencephalograph (EEG) signals in healthy subjects. We adopt autoregressive (AR) Burg method to estimate the power spectrum of EEG signals and analyze the relative powers in delta (0 Hz-4 Hz), theta (4 Hz-8 Hz), alpha (8 Hz-13 Hz), and beta (13 Hz-30 Hz) bands. Our results show that MA at ST36 can significantly increase the EEG slow wave relative power (delta band) and reduce the fast wave relative powers (alpha and beta bands), while there are no statistical differences in theta band relative power between different acupuncture states. In order to quantify the ratio of slow to fast wave EEG activity, we compute the power ratio index. It is found that the MA can significantly increase the power ratio index, especially in frontal and central lobes. All the results highlight the modulation of brain activities with MA and may provide potential helps in clinical treatment of acupuncture. The proposed quantitative method of acupuncture signals may be further used to make MA more standardized.     

Bursting synchronization in clustered neuronal networks

Neuronal networks in the brain exhibit the modular (clustered) property, i.e., they are composed of certain subnetworks with differential internal and external connectivity. We investigate bursting synchronization in a clustered neuronal network. A transition to mutual-phase synchronization takes place on the bursting time scale of coupled neurons, while on the spiking time scale, they behave asynchronously. This synchronization transition can be induced by the variations of inter- and intra- coupling strengths, as well as the probability of random links between different subnetworks. Considering that some pathological conditions are related with the synchronization of bursting neurons in the brain, we analyze the control of bursting synchronization by using a time-periodic external signal in the clustered neuronal network. Simulation results show a frequency locking tongue in the driving parameter plane, where bursting synchronization is maintained, even in the presence of external driving. Hence, effective synchronization suppression can be realized with the driving parameters outside the frequency locking region.     

针刺足三里的脊髓背根神经电信号非线性特征提取

神经系统在外部刺激下会呈现出丰富的放电模式,针刺作为对穴位的机械作用可以等效为对神经系统的一种外部刺激,在针刺刺激下神经系统会产生不规则的电信号.由于神经系统是高度复杂的非线性动力学系统,神经电信号具有很强的非线性,所以本文设计了提插补法、提插泻法、捻转补法、捻转泻法等四种针刺手法的动物实验,获取针刺大鼠足三里穴位的脊髓背根神经束动作电位序列.采用峰峰间期的思想,应用非线性时间序列的方法分析此动作电位序列,通过计算Lyapunov指数、关联维数以及Lempel-Ziv复杂度等参数,提取神经电信号的非线性特征,得到不同针刺手法的神经电信息的编码;并证明了针刺作用下脊髓背根的神经电信号具有明显的混沌特性. 关键词： 针刺 神经电信号 非线性分析 混沌     

High-power passively Q-switched Nd:GdVO_4 laser with a reflective graphene oxide saturable absorber

A single output Q-switched Nd:GdVO4 laser with a reflective graphene oxide(GO) saturable absorber was demonstrated. The shortest pulse duration in the Q-switched laser is 115 ns, and the output power ranges from1.23 W at 1.71 MHz to 2.11 W at 2.50 MHz when the pump power rises from 7.40 to 10.90 W with the utilization of GO Langmuir–Blodgett(LB) films based on the convenient and low-cost LB technique. To the best of our knowledge, it is the highest output power in a Q-switched laser with a GO saturable absorber.     

不对称合成手性3,5-二取代脯氨酸及其衍生物

选用甘氨酸等当体镍螯合物与α,β-不饱和酮进行不对称Michael加成反应,在室温条件下,以1,8-二氮杂二环十一碳-7-烯(DBU)为碱,甲醇为溶剂,不对称合成了3,5-二取代脯氨酸及其衍生物.该方法具有操作简单、收率高、底物适用范围广的特点,为3,5-二取代脯氨酸及其衍生物的不对称合成提供了新的研究思路.     

燃料电池中质子交换膜干涸的热物理机制

本文首次应用有内热源的多孔介质中流体流动与换热理论,对直接甲醇燃料电池中PEM中的传热过程和干涸 现象进行定量研究。建立了相应的数学物理模型并进行了数值求解。计算结果表明:反映水的热容量和膜的内部产热量的 两个无因次参数D和N是影响PEM中传热的主要因素;水的质量流率小和电流密度过高是造成膜干涸的主要原因。