A proteomic analysis of bacterial strain<Emphasis Type="Italic">Sinorhizobium fredii</Emphasis> RT19 subjected to salt shock

Sinorhizobium fredii RT19, a strain of freeliving bacteria, was subjected to salt shock and its protein expression profiles were analyzed by differential display proteome approaches. The results of separation by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) showed that the number of resolved proteins was 481, 465 and 424, corresponding to salt-free control, 5 and 50 min 1 mol/L salt treatment, respectively. Among the resolved proteins, 82 in total had altered expression in response to salt-shock stress. 26 out of the 82 proteins were induced and 23 were completely inhibited, while 12 were up-regulated and 21 down-regulated in response to salt shock. In addition, the appearance of differentially displayed proteins responding to different salt shock periods is also reported. The identity of the 26 induced proteins was revealed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) followed by database searching. Among them, 20 were assigned to proteins with known functions. Their roles in response to salt shock stress are discussed.     

川东鄂西山地紫色土发生探讨

本文研究表明,在试验区内,地质构造决定着紫色岩层的展布和紫色土的分布;老年、壮年、青年等不同地貌发育阶段则深刻影响和制约紫色土发生演化的方向.在现代成土条件下,各地类型紫色土的发育和岩石,既存在矿质元素的相对迁移和富集.也存在元素间的彼此制约关系.实质为碱金属、碱土金属在土壤剖层次间的淋溶作用.土壤淋溶系数5.90-14.960;岩石淋溶系数2.269-4.466.     

复合镀电触点耐电蚀机理的研究

采用X射线光电子谱对Ag-La_2O_3复合镀层进行了分析。结果表明,微粒在镀层中不是简单的机械夹杂,而是在接触界面处与周围的Ag原子发生化学作用,形成Ag、La、O非计量界面扩散反应层。文中讨论了荷负电徽粒的复合电沉积机理,以“微粒效应”和“电蚀中心”的观点解释Ag-La_2O_3复合镀电触点耐电蚀现象。     

微波促进伯溴代烷和乙酸钠亲核取代成酯的研究

在与传统加热法相似的操作条件下，研究了微波对乙酸钠和伯溴代烷亲核取代反应生成酯的影响，与传统加热法进行对比，用气相色谱对产物进行了定性和定量分析，结果表明在极性溶剂中微波辐射对该反应有很好的促进作用，不仅反应时间短、产率高，而且副反应少．     

ADAPTIVE SYSTEMS THEORY： SOME BASIC CONCEPTS, METHODS AND RESULTS

The adaptive systems theory to be presented in this paper consists of two closely related parts: adaptive estimation (or filtering, prediction) and adaptive control of dynamical systems. Both adaptive estimation and control are nonlinear mappings of the on-line observed signals of dynamical systems, where the main features are the uncertain-ties in both the system‘s structure and external disturbances, and the non-stationarity and dependency of the system signals. Thus, a key difficulty in establishing a mathematical theory of adaptive systems lies in how to deal with complicated nonlinear stochastic dynamical systems which describe the adaptation processes. In this paper, we will illustrate some of the basic concepts, methods and results through some simple examples. The following fundamental questions will be discussed: How much information is needed for estimation? How to deal with uncertainty by adaptation? How to analyze an adaptive system? What are the convergence or tracking performances of adaptation? How to find the proper rate of adaptation in some sense? We will also explore the following more fundamental questions: How much uncertainty can be dealt with by adaptation ? What are the limitations of adaptation ? How does the performance of adaptation depend on the prior information ? We will partially answer these questions by finding some “critical values“ and establishing some “Impossibility Theorems“ for the capability of adaptation, for several basic classes of nonlinear dynamical control systems with either parametric or nonparametric uncertainties.     

SnO_2簿膜(掺Sb)光学气敏选择性的实验研究

郑顺旋等人观察到常用的气敏-电阻型材料氧化锡薄膜的光学性质和气敏特性有关.这一发现突破了近半个世纪以来氧化物的气敏特性仅与电阻有关的模式.使得可以用光学量去探索至今还未清楚的氧化物气敏机理.也为新型气敏传感技术提供了有效的敏感材料.然而与气敏-电阻效应一样,纯SnO_2器件的气敏-光学效应对各种还原性气体的灵敏度几乎相同,因此制造出气体选择性良好的元件很不容易.为了提高SnO_2薄膜气敏光学效应的气体选择性,在纯SnO_2薄膜中掺杂了0.1wt%的Sb.实验观察     

ON LIMITATIONS OF THE SAMPLED—DATA FEEDBACK FOR NONPARAMETRIC DYNAMICAL SYSTEMS

In this paper, we study a basic class of first order sampled-data control systems with unknown nonlinear structure and with sampling rate not necessarily fast enough, aiming at understanding the capability and limitations of the sampled-data feedback. We show that if the unknown nonlinear function has a linear growth rate with its "slope" (denoted by L) being a measure of the "size" of uncertainty, then the sampling rate should not exceed 1/L multiplied by a constant (≈ 7.53) for the system to be globally stabilizable by the sampled-data feedback. If, however, the unknown nonlinear function has a growth rate faster than linear, and if the system is disturbed by noises modeled as the standard Brownian motion, then an example is given, showing that the corresponding sampled-data system is not stabilizable by the sampled-data feedback in general, no matter how fast the sampling rate is.     

在半导体硅上电沉积及激光诱导电沉积镍薄膜

利用激光诱导电沉积实验控制和数据采集系统考察了Ｎｉ在ｐ－Ｓｉ上沉积和阳极溶出过程。结果表明半导体表面自然氧化膜和阳极钝化膜导致阴极反应过电位大幅度增加,反应电流下降,且钝化膜导致暂态电流上升迟缓,Ｎｉ阳极溶出实验表明薄膜由活性不同的两种相结合组成,在电沉积初期可获得由平均尺寸３００～６００ｎｍ晶粒构成了光亮度层,晶粒尺寸随镀层加厚,迅速变大,薄膜表面失去光泽。     

论化工企业公用工程管路系统的故障与对策

详细分析了化工企业中各类公用工程管路的故障，并根据其各自的特点提出加强管理，改进工艺，减少废气排放，减少热应力，抑制“碱脆”的发生，减少介质与管壁间的摩擦等，即能有效地延长管路的使用寿命。     

Application of Dynamic Slicing in Test Data Generation

The program slicing technique is employed to calculate the current values of the variables at some interest points in software test data generation. This paper introduces the concept of statement domination to represent the multiple nests, and presents a dynamic program slice algorithm based on forward analysis to generate dynamic slices. In the approach, more attention is given to the statement itself or its domination node, so computing program slices is more easy and accurate, especially for those programs with multiple nests. In addition, a case study is discussed to illustrate our algorithm. Experimental results show that the slicing technique can be used in software test data generation to enhance the effectiveness.