Bis(7)-Tacrine Ameliorates Cognitive Impairment Caused by Cerebral Hypoperfusion in Rats

The effects of bis(7)-tacrine, a novel acetylcholinesterase inhibitor, on cognitive impairment and neuronal degeneration induced by permanent ligation of bilateral common carotid arteries (2VO) were investigated using the Morris water maze in rats. Once daily oral administration of bis(7)-tacrine (0.025, 0.05 and 0.1 mg\5kg-1) was started 14 days after 2VO operation. Over a three-week treatment bis(7)-tacrine effectively reversed 2VO-induced spatial memory deficits in a dose-dependent fashion. Furthermore, histological observation showed bis(7)-tacrine decreased the neuropathological changes in the 2VO rats brain. These results suggest that bis(7)-tacrine has therapeutic potential for the treatment of dementia caused by chronic cerebral hypoperfusion.     

三相异步电动机节能优化控制器的设计

三相异步电动机是一种广泛使用的动力机械，每年消耗的电能占我国总发电量的50％以上。电机拖动应用领域中浪费现象比较普遍。本节能优化控制器的特色是在降压节能过程中即考虑降压范围又进一步找到电压和电流的最佳工作点，该方案用于对51kW恒负载转矩准厚模块节能器的改造。具体介绍了该方案的节能原理，硬件结构和软件设计。     

纳米晶永磁Pr2Fe14B微磁学有限元法的模拟计算研究

根据实验数据，构造了接近实际纳米晶永磁Pr2Fe14B的样品，用微磁学有限元法进行了模拟计算.计算结果表明，晶界处各向异性的下降会导致矫顽力减小、剩磁值增大，而晶界处交换作用常数的减小则会使剩磁值减小、矫顽力增大.通过对实验样品的模拟研究发现，晶界处各向异性和交换作用常数的共同减小能够同时拟合出真实的矫顽力和剩磁值.模拟计算与实验在退磁曲线形状上的差距则说明模拟还存在不足. 关键词： 纳米晶永磁 磁滞回线 矫顽力 剩磁     

轻质绿化混凝土pH值优化的正交试验研究

利用正交试验探讨了水泥、耕植土、珍珠岩和外加剂等因素对轻质绿化混凝土pH值的影响.结果表明:各因素对轻质绿化混凝土pH值的影响具有明显的时间效应,28 d pH值的降幅最大,7 d前水泥、珍珠岩和外加剂的影响达到显著水平,而28 d后水泥是pH值和28 d抗压强度的主要影响因素,基本上与水泥用量呈线性关系,达到显著水平,并趋于稳定,珍珠岩用量的增加有进一步降低pH值的趋势.28 d后的综合最优水平组合为A1B1C2D3,在实际应用中应按工程实际合理选择各因素的用量.     

六层加侧混合型摇摆器磁场的理论计算与数值模拟

 利用文献[1，2]给出的结果，提供了六层加侧混合型摇摆器中永磁体磁场的计算公式和软铁磁场计算的积分方程式。对周期长度lw =1.6cm，磁极间隙g=0.5cm的情况，计算了单向聚焦和双向聚焦两种不同构形的磁场分布，并得到了g /lw =1/3条件下，峰值磁场Bw超过1特斯拉的设计指标。     

Structure comparison between Th2Zn17-type and TbCu7-type Sm–Fe intermetallic compounds and their nitrides by means of 57Fe-Mössbauer spectroscopy

Samarium–iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th₂Zn₁₇-type and a TbCu₇-type structure, respectively. Structure comparison between these types was investigated for Sm–Fe intermetallic compounds and their nitrides by ⁵⁷Fe-Mössbauer spectroscopy.     

An upper bound for permanents of nonnegative matrices

A recent conjecture of Caputo, Carlen, Lieb, and Loss, and, independently, of the author, states that the maximum of the permanent of a matrix whose rows are unit vectors in lp is attained either for the identity matrix I or for a constant multiple of the all-1 matrix J.The conjecture is known to be true for p=1 (I) and for p?2 (J).We prove the conjecture for a subinterval of (1,2), and show the conjectured upper bound to be true within a subexponential factor (in the dimension) for all 1<p<2. In fact, for p bounded away from 1, the conjectured upper bound is true within a constant factor.     

Highly sensitive and interference-free determination of bismuth in environmental samples by electrothermal vaporization atomic fluorescence spectrometry after hydride trapping on iridium-coated tungsten coil

Bismuthine was on-line trapped on tungsten coil and subsequently electrothermally vaporized for the determination by atomic fluorescence spectrometry (AFS). Several noble metals, including Pd, Rh, Pt, and Ir, were explored as permanent chemical modifier for tungsten coil on-line trapping. Investigation showed that Ir gave the best performance, in which bismuthine was on-line trapped on Ir-coated tungsten coil at 560 °C, and then released at 1550 °C for subsequent transfer to AFS by a mixture of Ar and H₂. Under optimum instrumental conditions, the trapping efficiency was found to be 73 ± 3%. With 120 s (12 mL sample volume) trapping time, a limit of detection (LOD) of 4 ng L^− 1 was obtained, compared to conventional hydride generation AFS (0.09 μg L^− 1); the LOD can be lowered down to 1 ng L^− 1 by increasing the trapping time to 480 s. The LOD was found to be better or at least comparable to literature levels involving on-line trapping and some other sophisticated instrumental methods such as ICP-MS and GF-AAS. A comprehensive interference study involving conventional hydride-forming elements and some transition metals was carried out, and the result showed that the gas phase interference from other hydride-forming elements was largely reduced, thanks to the use of on-line tungsten coil trapping. Finally, the proposed method was applied to the determination of bismuth in several biological and environmental standard reference materials, and a t-test shows that the analytical results by the proposed method have no significant difference from the certified values at the confidence level of 95%.     

ECR离子源六极永磁体的设计研究

分别从材料、结构、尺寸等方面全面地研究了Halbach结构六极永磁铁的设计方法.针对个别磁块可能存在的退磁问题给出了相应的解决方案.通过优化结构,使六极磁铁在离子源等离子体弧腔内壁产生的磁场达到最大.用POISSON,PERMAG,TOSCA等多个磁场模拟程序计算模拟了六极磁场的大小与分布,并给出了一些相应的曲线     

永磁除铁装置表面最佳磁感应强度的实验确定方法

在设计永磁除铁装置时，一个关键问题就是吸附表面磁感应强度的确定。在保证吸净率最高的条件下，必须确定其吸附表面磁感应强度大小，以确保除铁装置处于最佳运行状态。本文在大量实验的基础上，给出了测定表面磁感应强度的最佳值方法。