MCF5282的I2C总线在uClinux操作系统下的驱动程序设计

介绍了Freescale公司嵌入式微处理器MCF5282的原理、特点,给出了该处理器在嵌入式操作系统uClinux下通过I2C硬件扩展数字输入的原理,以及I2C总线的驱动程序设计流程.     

NMDA Receptor Modulation of Incidental Learning in Pavlovian Context Conditioning.

Rats exposed to a footshock show conditional fear when reexposed to the shock context. Immediate presentation of shock after placement in the context significantly reduces this fear. Preexposure to the context in the absence of shock, coupled with a minimum preshock interval during training, overcomes this immediate shock deficit. Because rats learn about the context during preexposure and express that learning after being reinforced, the context preexposure effect is an aversive analogue of latent learning. The authors examined the effect of the N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphovalerate (APV) on the facilitatory effect of context preexposure. Rats were preexposed to a chamber after APV administration. The next day they were placed in the same chamber without drug and received shock 35 s later. APV blocked the facilitatory effect of preexposure. Therefore NMDA receptors are important for contextual latent learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

抗真菌蛋白Rs-AFP2基因定点突变及其对大肠杆菌中表达的影响

为了研究遗传密码子对表达调控的影响,利用PCR重叠延伸法,对萝卜抗真菌蛋白Rs-AFP2基因编码序列区的部分核苷酸进行沉默突变,构建突变体Rs-AFPm.序列分析表明,PCR产物全长240bp,有一个阅读框,编码的蛋白由29个氨基酸的信号肽和51个氨基酸的抗真菌蛋白组成.突变体与突变前的Rs-AFP2基因相比,在编码区第3号氨基酸Lys相差一个碱基(TTG→TTA),第5号氨基酸Gln相差一个碱基(CAG→CAA),第6号稀有密码子Arg相差两个碱基(CAG→CGA).重新合成引物,将切除信号肽的Rs-AFP2基因和Rs-AFPm基因与原核表达载体pET-21b(+)分别重组到大肠杆菌BL21菌株.IPTG诱导后,二者均得到了表达.软件分析显示,突变前pETAFPo表达产物占全菌蛋白的3%,突变后pETAFPm的表达产物占全菌蛋白含量的8%;表达蛋白主要以包涵体的形式存在,包涵体经超声波破碎后,蛋白质复性,抑菌结果表明,pETAFPm表达产物的抑菌半径大于pETAFP2表达产物的抑菌半径.这些都说明改造后的Rs-AFPm基因与Rs-AFP2基因相比,已有效地提高表达量.     

模糊层次分析法在腐蚀影响因素分析中的应用

结合国内外对碳钢CO2腐蚀影响因素的研究成果,采用模糊层次分析法对影响输油管道 CO2腐蚀的因素进行定量分析,明确界定出这些因素对二氧化碳腐蚀影响的相对重要性(权重),为后续制定经济有效的管道内腐蚀防护措施提供了客观依据。     

基于ISP1581的USB2.0键盘数码管控制设备的固件编程

基于ISPl581的USB2．0键盘数码管控制设备的设计严格遵循USB2．0协议，体现了USB即插即用、易扩展、低干扰的特点，实现了主机和设备之间简单、快速、可靠的连接和通信。文章介绍了基于ISP1581的USB2．0键盘数码管控制设备的硬件、软件的设计方法。     

万家寨引黄工程北干1号隧洞Ⅳ标155-274型TBM主轴承总成组装概要

文中对万家寨引黄工程北干线1号隧洞Ⅳ标使用的155—274型TBM主轴承总成各部件组装过程及其相应的技术要求进行了概要的描述，目的是进一步熟悉155—274型TBM主轴承总成的各个部件并加深对主轴承工作原理的理解。     

草酸钙在硫酸软骨素自组装膜上周期沉淀的研究

利用硫酸软骨素(chondroitin sulfate，CS)在云母基底上通过浇铸法制备的自组装膜为基底，诱导草酸钙在其上的凝集生长。发现当硫酸软骨素的浓度为1．Omg／ml时在该膜体系中可形成规整的周期性草酸钙环状沉淀。这种有序的环状结构可能是耗散结构的一种具体表现形式。利用原子力显微镜(atomic forcemicroscope，AFM)和傅立叶红外光谱仪对这种结构进行了表征，实验结果显示合适浓度下形成的CS膜在一定程度上可以抑制草酸钙的凝集结晶，表明高分子基质与无机离子间强烈的相互作用对无机盐的成核结晶有显著影响，为探讨结石的形成与抑制提供了一定的实验依据。     

Synchronous Full-Scan for Asynchronous Handshake Circuits

Handshake circuits form a special class of asynchronous circuits that has enabled the industrial exploitation of the asynchronous potential such as low power, low electromagnetic emission, and increased cryptographic security. In this paper we present a test solution for handshake circuits that brings synchronous test-quality to asynchronous circuits. We add a synchronous mode of operation to handshake circuits that allows full controllability and observability during test. This technique is demonstrated on some industrial examples and gives over 99% stuck-at fault coverage, using test-pattern generators developed for synchronous circuits. The paper describes how such a full-scan mode can be achieved, including an approach to minimize the number of dummy latches in case latches are used in the data path of the handshake circuit.     

Physico-chemical characterization of hybrid polymers obtained by 2-hydroxyethyl(methacrylate) and alkoxides of zirconium

Hybrid monolithic materials were prepared through polymerisation of 2-hydroxyethyl methacrylate (HEMA) mixed with zirconium alkoxides (Zr(OBuⁿ)₄, Zr(OPrⁿ)₄ and Zr(OEt)₄), modified by acetylacetonate groups. The molar ratio HEMA/Zr varied between 1 and 4. Thermo-Gravimetry coupled with Mass Spectroscopy (TG-MS) analyses, ¹³C MAS NMR and Dynamical Mechanical Thermal Analysys (DMTA) indicated the polymeric chains were interconnected by the inorganic component.The presence of zirconium alkoxides modified substantially the poly-HEMA properties. Glass transition temperature of hybrid materials derived from butoxy and propoxy was found in the range 50-80 °C, depending on the composition. The typical swelling of p-HEMA in the water, was suppressed by the presence of zirconium compounds. After immersion in distilled water, hybrid polymers showed an initial slight weight increase, followed by a small mass loss, which increases proportionally to the length of alkoxyl group (ethoxide(propoxide(butoxide) and reaches a constant value after about 40 days. The hybrids remained always rigid and transparent. Flexural modulus and strength of about 400-900 and 4-8 MPa were measured.