Pa-239 may influence astrophysics study

The estimation method of the universe age using the nuclear cosmochronology by the heavy chronometers is essentialized. The influence of the novel long half-life of Pa-239 on the universe age estimation is simply mentioned.

Properties of ethylene-propylene copolymer/PA-1010 blends using ethylene-propylene copolymer-graft-acrylic acid as a compatibilizing agent

The modification of ethylene-propylene copolymer (EP) has been accomplished by radical EP-graft-acrylic acid (EP-g-AA) has been used to obtain ternary PA/EP/EP-g-AA blends by melt mixing. Different blend morphologies were observed by scanning electron microscopy; the domain size of the EP-dispersed phase in the polyamide 1010 matrix of compatibilized blends decreased compared with that of uncompatibilized blends. It is found that EP-g-AA used as the third component has a profound effect on the mechanical properties of the resulting blends. This behavior has been attributed to serious chemical interactions taking place between the two components. Thermal analysis shows that some thermal properties of PA in compatibilized PA/EP/EP-g-AA changed because of chemical reactions taken place during the blending process. Wide angle x-ray diffraction measurements also confirmed this result. (C) 1996 John Wiley & Sons, Inc.

辐射交联型PA－66机械物理性能研究

本文讨论了进口与国产ＰＡ—６６经钴源辐射交联后，对机械物理性能产生的影响。发现适量经辐射的ＰＡ—６６球压硬度、拉伸强度、Ｉｚｏｄ冲击强度都有较大幅度提高，并在１００，０００Ｇｙ剂量对达最大值，而断裂伸长率在１００，０００Ｇｙ剂量以下变化不大。国产ＰＡ—６６辐射后在乙二醇中，在２５０℃时，２小时不起层，性能变化不大，可替代进口材料。

SYNTHESIS AND CHARACTERIZATION OF HIGH-PERFORMANCE PA FILM

I. INTRODUCTIONIn last decade, considerable attention was focused on polyacetylene. However, its practical application was affected considerably because of its poor strength and stability. Recently, Narrmann et al. reported that they could synthesize PA film with improved properties using modified Ziegler-Natta catalyst. However, no detailed

Recombinant expression of rt-PA gene (encoding Reteplase) in gametophytes of the seaweed Laminaria japonica (Laminariales, Phaeophyta)

The life cycle of seaweed Laminaria japonica involves a generation alternation between diploid sporophyte and haploid gametophte. The expression of foreign genes in sporophte has been proved. In this research, the recombinant expression in gametophyte was investigated by particle bombardment with the rt-PA gene encoding the recombinant human tissue-type plasminogen activator (Reteplase), which is a thrombolytic agent for acute myocardial infarction (AMI). Transgenic gametophytes were selected by their resistance to herbicide phosphiothricin (PPT), and proliferated in an established bubble column photo-bioreactor. According to the results from quantitative ELISA, Southern blotting, and fibrin agarose plate assay (FAPA) for bioactivity, it was showed that the rt-PA gene had been integrated into the genome of gametophytes of L. japonica, and the expression product showed the expected bioactivity, implying the proper post-transcript modification in haploid gametophyte.

第十四章 WIA-PA:用于过程自动化的工业无线网络系统结构与通信规范

概要介绍工业无线网络的标准化进程,详细介绍了用于过程自动化的工业无线网络WIA规范的网络构成、拓扑结构、协议体系和关键技术,并将WIA-PA与WirelessHART、ISASP100两大工业无线标准进行了比较分析。

PROFIBUS PA通信协议软件开发

随着控制技术、计算机技术、通信技术的飞速发展，现场总线技术正逐渐取代集散控制技术。PROFIBUS现场总线技术作为应用最为广泛的现场总线技术之一，截止至2008年8月，其安装节点已经超过2500万个，市场份额超过20%。 本文首先深入研究了现场总线国际标准IEC61158-Type3(PROFIBUS标准)，分析了PFOFIBUS 现场总线的层次结构模型、各层功能及层间通信关系，然后介绍了PROFIBUS PA的功能块模型，包括块的构成、分类、参数详解，以及把功能块模型映射到模块化DP从站设备的规则等。然后本文采用uC/OS-II嵌入式实时操作系统作为软件平台，应用瑞萨公司M16C/62P系列MCU与中科院沈阳自动化研究所自主研发的FBC0409现场总线通信控制器作为硬件平台，开发了支持PROFIBUS DPV0和DP V1的通信协议栈，并根据PA应用行规(V3.01)编写了相应的功能块程序，并且进行了验证。 本文给出了PROFIBUS DPV0、DPV1实现过程中的主要数据和功能定义，介绍了各层任务的创建初始化，处理过程，绘制了相关的软件流程图。本文给出了编写物理块、功能块、变换块和设备管理的参数定义和读写函数的方法。

环境变迁在中国文明形成中的作用

The formation of civilization, one of great marks in the history of human's society development, has been remained one of the hottest topics in the world. Many theories have been put ford to explain its causes and mechanisms. Although more attentions have been paid to its development, the role of environmental change should not be ignored. In this paper, the level of ancient farming productivity was analyzed, the mechanisms and the process of Chinese ancient civilization formation was explored, and some causes why Chinese ancient civilization shows many different features from other 5 ancient civilizations of the world was analyzed. The main results and conclusions are presented as followed. 1. Compared with the productivity level of other five ancient civilizations, the productivity of ancient China characterized by a feature of extensive not intensive cultivation was lower than that of other five ancient civilizations whose agriculture were based on irrigation. 2. The 5 5000 a B.P. cold event may have facilitated the formation of Egypt and Mesopotamian ancient civilizations and also have had an influence on the development of Neolithic culture in China. 3. The 4 000 a B.P. cold event, which may be the coldest period since the Younger Dryas cold event and signifies the changes from the early Holocene Climate Optimum to late Holocene in many regions of the world, resulted in the great migration of the Indo-European peoples from north Europe to other part of the World and the collapses of ancient civilizations in Egypt, Indus and the Mesopotamian and the collapse of five Neolithic cultures around central China. More important than that is the emergence of Chinese civilization during the same period. Many theories have been put ford to explain why it was in Zhongyuan area not other places whose Neolithic cultures seem more advanced that gave rise to civilization. For now no theory could explain it satisfiedly. Archaeological evidence clearly demonstrate that war was prevailed the whole China especially during the late Longshan culture period, so it seemed war has played a very important role in the emergence of China ancient civilization. Carneiro sees two conditions as essential to the formation of complex societies in concert with warfare, i.e. population growth and environmental circumscription. It was generally through that China couldn't evolved into the environmental circumscription and population pressure because China has extensive areas to live, but that depends on situations. The environmental circumscription area was formed due to the 4000a B.P. cold event and companied flooding disasters, while the population pressure is formed due to three factors; 1) population grow rapidly because of the suitable environment provided by the Holocene Optimum and thus laid its foundations for the ancient human population; 2) population pressure is also related to the primitive agricultural level characterized by extensive not intensive cultivation; 3) population pressure was mainly related to the great migrations of people to the same areas; 4) population pressure was also related to productivity decrease due to the 4 000a B.P. cold event. 4. When population pressure is formed, war is the most possible way to solve the intensions between population and the limited cultivated land and then resulted in the formation of civilization. In this way the climate change during the 4 000a B.P. cold event may have facilitated the emergence of Chinese ancient civilization. Their detailed relations could also be further understood in this way: The first birth places of China ancient civilization could be in Changjiang areas or (and) Daihai area, Shandong province rather than in central China and the emergence time of ancient civilization formed in central China should be delayed if the 4 000a B.P. cold event and companied flooding disasters didn't occurred.