二维金纳米微粒有序阵列的制备

对于用十二烷基硫醇包覆的金纳米微粒，用Langmuir-Blodgett(LB)技术制备了二维金纳米微粒有序阵列．在单纯的硫醇包覆的金纳米微粒形成的LB膜中，由于硫醇分子之间的疏水相互作用，容易导致金纳米微粒的自组织而在LB膜中形成缺陷．为了改善金纳米微粒的成膜性能和提高金纳米微粒阵列的有序性，正十二醇作为添加剂和润滑剂加入到金纳米微粒的氯仿溶液中与金纳米微粒一起形成LB膜．用透射电子显微镜对金纳米微粒的二维阵列进行了表征．结果表明，正十二醇的加入可以有效地减少用LB技术制备的二维金纳米微粒阵列中的缺陷，提高金纳米微粒阵列的有序性．     

百麦外用中药制剂对小鼠乳腺增生的实验研究

目的:观察外用中药制剂对小鼠乳腺增生的预防作用并探讨其机理。方法:采用苯甲酸雌二醇腹腔注射造模,分对照组、模型组与预防组。模型组与预防组腹腔注射苯甲酸雌二醇,隔天1次,并且预防组小鼠乳房涂抹百麦外用中药制剂,每天1次,共30天;对照组小鼠腹腔注射生理盐水,隔天1次,共30 d。测定各组小鼠体重变化,乳晕及乳头直径变化,血清雌激素(E2)、孕激素(P)指标,并取小鼠第二对乳房组织病理切片检查。结果:预防组与模型组小鼠体重、乳晕及乳头直径比较均有显著性差异(P0.05);预防组与模型组比较,E2水平明显降低(P0.05),P水平明显升高(P0.05);预防组小鼠增生的乳腺小叶、腺泡数、腺泡腔直径、导管直径以及胞浆面积较模型组降低。结论:百麦外用中药制剂具有预防乳腺增生的作用,其机理可能是通过抑制血清雌二醇水平而实现。     

摩擦非线性环节的特性、建模与控制补偿综述

首先介绍了机械伺服系统中摩擦非线性环节的动态、静态特性的研究成果和目前常用的几种摩擦模型 ,讨论了摩擦非线性环节对伺服系统的动态性能和静态性能的影响 ,以及摩擦非线性环节导致的极限环振荡、低速爬行等现象。然后对有关摩擦补偿方法方面的研究成果进行了总结 ,介绍了传统的摩擦补偿方法和基于智能控制理论的摩擦补偿方法方面的研究成果。最后 ,展望了该领域今后的发展方向。     

多参考预测链的时域可扩展性和抗错性

网络的带宽抖动和数据传输错误是影响视频传输的重要原因。该文提出了一种新的多参考帧图像预测的视频编码算法,即多参考预测链,使视频具有时域可扩展性和抗错性解决网络的这两个潜在问题。该算法中P帧之间的参考预测关系构成多条链状结构,使视频具有时域可扩展性。链间的不相关性使每个链可独立解码,从而增强了码流抗错性。该算法采用R-D框架动态的管理预测关系链,从而适合网络带宽的变化而获得最佳的终端视觉效果。仿真实验表明,采用多参考预测链编码的码流时域可扩展性的应用非常可行,且表现出较高的抗错性。     

A novel route for ATP acquisition by the remnant mitochondria of Encephalitozoon cuniculi

Mitochondria use transport proteins of the eukaryotic mitochondrial carrier family (MCF) to mediate the exchange of diverse substrates, including ATP, with the host cell cytosol. According to classical endosymbiosis theory, insertion of a host-nuclear-encoded MCF transporter into the protomitochondrion was the key step that allowed the host cell to harvest ATP from the enslaved endosymbiont. Notably the genome of the microsporidian Encephalitozoon cuniculi has lost all of its genes for MCF proteins. This raises the question of how the recently discovered microsporidian remnant mitochondrion, called a mitosome, acquires ATP to support protein import and other predicted ATP-dependent activities. The E. cuniculi genome does contain four genes for an unrelated type of nucleotide transporter used by plastids and bacterial intracellular parasites, such as Rickettsia and Chlamydia, to import ATP from the cytosol of their eukaryotic host cells. The inference is that E. cuniculi also uses these proteins to steal ATP from its eukaryotic host to sustain its lifestyle as an obligate intracellular parasite. Here we show that, consistent with this hypothesis, all four E. cuniculi transporters can transport ATP, and three of them are expressed on the surface of the parasite when it is living inside host cells. The fourth transporter co-locates with mitochondrial Hsp70 to the E. cuniculi mitosome. Thus, uniquely among eukaryotes, the traditional relationship between mitochondrion and host has been subverted in E. cuniculi, by reductive evolution and analogous gene replacement. Instead of the mitosome providing the parasite cytosol with ATP, the parasite cytosol now seems to provide ATP for the organelle.     

Bit-Depth Scalable Coding Using a Perfect Picture and Adaptive Neighboring Filter

Bit-depth scalability is a new research field in the on-going scalable extension of the H.264/AVC (SVC) video coding standard. The key point is to accurately predict the enhancement layer, whose bit depth is 10 or more, from the 8 bit base layer. An improved inter-layer prediction scheme for bit-depth scalability was developed that ensures compatibility with the standard and improves the encoding efficiency. The scheme uses a “perfect” 8 bit picture with an adaptive neighbor filter whose coefficients are optimized by minimizing the block distortion between the 8 bit reconstructed picture and the “perfect” picture to achieve a more precise 10 bit prediction based on the filtered picture. Double arithmetic precision is used to further improve the encoding efficiency. Experimental results show that the scheme outperforms the recent joint video team (JVT) proposal in the joint scalable video model (JSVM).     

基于神经网络的直流电动机实时跟踪控制

研究了三层对角回归神经网络(DRNN)用于直流电动机实时控制的方法.首先采用动态反传算法训练神经网络以辨识直流电动机的逆模型,然后将这一训练后的网络作为前馈控制器与常规反馈控制器一起输出控制电压,以控制系统跟踪位置或速度指令.该算法简单、计算量小,适于实时控制.仿真结果表明了该方法的有效性.     

非晶态半导体多层膜的TEM及HREM研究

本文介绍了非晶态半导体多层膜剖面电镜样品的一种制备方法.报导了周期性调制和准周期性调制的非晶态半导体多层膜的剖面透射电子显微像和其对应的电子衍射花样的性质.通过高分辨电子显微像,研究了组成多层膜的子层材料的微观结构特性和异质结的界面性质.     

闪锌矿结构CdS量子点的电子结构:紧束缚近似下一种新的计算方法

在紧束缚近似下发展了一种新的计算方法，计算了闪锌矿结构CdS量子点的电子结构，并与有效质量近似作了比较。这种计算方法比较简洁，在K－空间进行计算，结果却与实空间复杂计算的结果一致。紧束缚近似的理论结果在很大范围内可与实验结果相符合。结果表明，紧束缚近似下K空间的计算方法是一种简单有效的方式，可以扩展到其它材料和结构。     

飞行转台Backstepping与神经网络并行控制

阐述了飞行仿真转台的Backstepping设计方法及步骤。在Backstepping鲁棒控制的基础上,提出了一种Backstepping鲁棒控制和神经网络并行控制的方案,以Backstepping鲁棒控制为主控制器,神经网络进行动态误差补偿。Backstepping鲁棒控制克服了对象的不确定性,保障系统的鲁棒性;神经网络可以进一步提高系统的跟踪精度。仿真表明,这种方法实现了Backstepping鲁棒控制和神经网络控制的完美结合,很适合高精度飞行仿真转台系统的鲁棒控制。