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221.
Effects of rhubarb extracts on hyperexcitability of hippocampal CA1 neurons after fluid percussion injury 总被引:1,自引:0,他引:1
Objective To investigate the effects of rhubarb extracts, i.e. rhein and emodin, on the neuronal hyperexcitability and synaptic transmission, and to ,further reveal the mechanism of the secondary brain damage. Methods The fluid percussion injury (FPI) rat model and extracellular recording method were used. The evoked field potentials by stimulating Schaffer collaterals were collected from the ipsilateral (impact side) and the contralateral hippocampal CA1 areas of rat in vitro . And the field potentials, including the field excitatory postsynaptic potential and the population spike, were analyzed. Results After the impact was performed on the rat parietal cortex, the evoked field potentials in the ipsilateral hippocampus CA1 area were enhanced obviously. Rhubarb extracts reduced the slope of the field excitatory postsynaptic potential and the number of the population spike significantly while rhein and emodin increased the latency of the population spike obviously. Conclusion Rhubarb extracts, i.e. rhein and emodin, can depress the neuronal hyperexcitability, which suggests that rhein and emodin play an important role in protecting the central nervous system from neuronal damage after traumatic brain injury. FPI produces hyperexcitability of hippocampal CA1 neurons, probably by enhancing excitatory synaptic transmission. 相似文献
222.
Introduction Submerged floating tunnel ( SFT) provides acomplete new option for crossing of waterways, andcan connect both lands and channels where appropri-ate[1-5]. Being a structure not buried deeply in theground, but suspended in a certain depth below… 相似文献
223.
北京现代ix35是一款追求时尚、充满激隋活力的全新SUV车型,在法兰克福设计研发也为其注入了一些欧系车基因,因此我们用更加严格的标准来审视它也就不足为奇了。 相似文献
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226.
垮塌区Navier-Stokes幂律型浆体的有效扩散范围 总被引:1,自引:1,他引:0
为了研究注浆过程水泥浆体在破碎岩体中的扩散范围和压力分布状态,以Navier-Stokes方程为理论基础,在COMSOL平台上建立单裂隙模型,模拟浆体在不规则的单一裂隙面上的流动特征. 在此基础上,建立破碎岩体的平面裂隙模型,同时设置不同的贯通系数,模拟浆体在破碎岩体中的扩散规律. 研究结果表明:当模型中裂隙贯通系数较低时(0.1~0.5),浆体有效扩散范围较小,约为1.5~4.1 m,扩散范围随着压差的增加呈非线性的增加,但是增加率快速降低接近0;当模型中裂隙贯通系数较大时(0.5~1.0),浆体的有效扩散范围显著增加,约为4.1~6.2 m,随着压差的增加也呈非线性增加,增加率呈降低的趋势;当模型中裂隙贯通系数为1.0时,即破碎的岩体中裂隙面全部连通状态,浆体扩散距离随着压差的增加近似呈线性增加,最大扩散距离约为6.2 m. 同时在注浆孔外围6 m处取芯结果能明显观察到浆体固结的破碎岩块,这与模型计算结果一致. 相似文献
227.
将磁流变液(MR)智能阻尼器并联于传统的被动隔震装置上形成智能复合隔震系统,并采用半主动控制策略对该系统实施智能控制。通过对一栋三层的振动台试验模型的仿真分析表明:在不影响隔震效果的同时大大的减小了隔震层的相对位移;半主动控制策略能有效控制智能复合隔震系统。 相似文献
228.
Sloshing phenomenon in the liquid cargo carriers has caught the attention of researchers as the interaction between the sloshing
waves and structure is one of the key point and difficulty in the study of sloshing. In this paper, we captured the free surface
with a volume of fluid (VOF) method and then calculated the motions and responses of the structure by adopting the Reynolds-averaged
Navier-Stokes (RANS) equations for the whole fluid domain. With the use of user defined functions (UDF) in Fluent, the interaction
between fluid and structure was then simulated. As a reasonable simplification, the authors studied the response of a single
cantilever in a tank under sloshing loads; Further study should pay more attention to the mechanisms of interaction between
sloshing waves and elastic structures. 相似文献
229.
M. Y. Abdollahzadeh Jamalabadi 《船舶与海洋工程学报》2014,13(3):281-290
In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model of the flow is developed and the analytical results are obtained for both the cylindrical and Cartesian configurations that are proper to use in the propulsion of marine vessels. The governing parabolic momentum PDEs are transformed into an ordinary differential equation using approximate velocity distribution. The numerical results are obtained and asymptotic analyses are built to discover the mathematical behavior of the solutions. The maximum velocity in a magneto-hydro-dynamic pump versus time for various values of the Stuart number, electro-magnetic interaction number, Reynolds number, aspect ratio, as well as the magnetic and electrical angular frequency and the shift of the phase angle is presented. Results show that for a high Stuart number there is a frequency limit for stability of the fluid flow in a certain direction of the flow. This stability frequency is dependent on the geometric parameters of a channel. 相似文献