Flowrate behavior and clustering of self-driven robots in a channel

In this paper, the collective motion of self-driven robots is studied experimentally and theoretically. In the channel,the flowrate of robots increases with the density linearly, even if the density of the robots tends to 1.0. There is no abrupt drop in the flowrate, similar to the collective motion of ants. We find that the robots will adjust their velocities by a serial of tiny collisions. The speed-adjustment will affect both robots involved in the collision, and will help to maintain a nearly uniform velocity for the robots. As a result, the flowrate drop will disappear. In the motion, the robots neither gather together nor scatter completely. Instead, they form some clusters to move together. These clusters are not stable during the moving process, but their sizes follow a power-law-alike distribution. We propose a theoretical model to simulate this collective motion process, which can reproduce these behaviors well. Analytic results about the flowrate behavior are also consistent with experiments.     

高载酶量酶/酶免疫电极的制备及其电化学机理研究

本文利用扫描电镜和电化学方法确定了最佳镀铂电位,并进一步研究了酶电极和酶免疫电极在基体电极镀铂和未镀铂条件下的米氏常数、电化学反应速率常数和反应速度控制步骤。比较分析了生物电极的最佳实验条件。     

MDMV外壳蛋白基因的克隆及其在大肠杆菌中的表达

报道了玉米矮花叶病毒(MDMV)全长外壳蛋白cDNA基因的克隆、序列分析和表达产物鉴定的结果。根据其cDNA序列推测的外壳蛋白氨基酸顺序全长共有313个氨基酸,分子量总和为35 400 D,与聚丙烯酰胺凝胶电泳估算的值36 000 D相近,克隆的病毒外壳蛋白基因cDNA 3′-末端非编码区含有256个碱基。将此外壳蛋白的基因插入pUC19的1acZ基因中,转入E.coli后诱导表达,聚丙烯酰胺凝胶电泳分析呈现一特异性的蛋白带,经Western吸印与抗MDMV的兔血清呈阳性反应,证实所克隆的cDNA基因为MDMV外壳蛋白基因,并且能够正确表达。     

甜菜黄脉坏死病毒RNA3和RNA4有生物活性体外转录产物及功能研究

甜菜黄脉坏死病毒RNA3和RNA4全长cDNA的合成是分别以Oligo-d(T)_(15)为引物合成第一链cDNA,cDNA的第二链的合成则分别应用RNA3和RNA4特异引物完成。全长双链cDNA分别克隆在pGEM3Zf(+)载体中,置于噬菌体Sp6启动子控制下。在体外以质粒DNA为模板应用“run off”系统及Sp6RNA Polymerase成功地合成了大量的具有高度生物活性的转录产物RNA3和RNA4。在两种转录反应系统中,以第一种方法即转录与加帽(capping)分步进行转录效率高,第二种方法(转录与加帽同时进行)转录效率较低,但转录产物侵染性更高。虽然在RNA3和RNA4转录产物的5′末端和3′末端分别含数目不同的非病毒核酸序列,但转录产物的活性并未受到显著的影响。应用这种具有高度生物活性的体外转录产物与该病毒Rg1分离物机械接种甜菜幼苗根毛,首次阐明了RNA3是导致甜菜丛根病的主要因素。     

牛蒡矮化类病毒(BSV)的研究——BSV-RNAs的变性行为和在植株中的分别存在

本文用双向聚丙烯酰胺凝胶电泳技术,研究了BSV—RNAs的变性行为,进一步证实了它们具有环状分子结构。1980—1983年对BSV—RNAs在不同植株中分布的电泳分析证明,BSV—RNA—1和BSV—RNA—2分别存在于不同的植株中。从含BSV—RNA—1的病叶诱导的愈伤组织的生长比健叶的缓慢。BSV—RNA—1可在愈伤组织中连续复制8个月以上,表明它具有类病毒复制的特征。     

中国南瓜曲叶病毒:一个双生病毒新种

本文报道了中国南瓜曲叶病毒(SqLCV-C)外壳蛋白(CP)基因PCR、克隆和序列分析,在分子水平上证实中国南瓜曲叶病毒与美国南瓜曲叶病毒(SqLCV-E)不同,是一种新的粉虱传播的双生病毒,并与印度木薯花叶病毒(ICMV)有较近的亲缘关系。     

一株新黄瓜花叶病毒卫星RNA结构和生物学分析

从患香蕉花叶心腐病香蕉病叶分离的黄瓜花叶病毒中,发现一株新卫星RNA(定名为Ba-Sat)。以CMV卫星RNA两端保守序列为引物合成了Ba-Sat cDNA并将其克隆到载体pGEM7Zf(+)上。序列分析结果表明,Ba-Sat由390个核苷酸组成,其5′端、3′端各有一段序列与其它株系卫星RNA有很高的序列同源性,但其中间区域则无任何序列同源性。在此基础上,进一步分析了Ba-Sat的二级结构,并研究了Ba-Sat的生物学特征,实验结果证明Ba-Sat具有致弱卫星RNA的特性。     

由卫星互补DNA单体构建的抗黄瓜花叶病毒的烟草基因工程植株

本文将合成的卫星RNA-1的全长cDNA单体重组到含CaMV-35S启动子的植物表达载体ROK_2上,并将此重组质粒转入含Ti质粒的根癌杆菌(Agrobacterium tumefaciens)中,用以感染我国推广烟草品种G-140的叶圆片并再生成植株。经CMV强毒分离物接种后,大部分转化植株有大量卫星RNA表达,并表现出症状的减轻。第二代转基因植物仍保持大量卫星RNA的表达及对CMV的抗性并出现基本符合孟德尔遗传规律的分离。经分离和选育我们可得到纯化的抗病毒品种。     

STUDY ON BURDOCK STUNT VIROID (BSV)——THE DENATURING BEHAVIOR AND OCCURRENCE IN SEPARATE PLANT OF BSV RNA-1 AND RNA-2

By two-dimensional electrophoretic technique, it was confirmed that BSV RNA-1 and RNA-2 contained circular molecules and that they Were more stable than the ether viroids in thermodynamics. BSV RNAs extracted from individual diseased plants gave only one specific band on analytical polyacrylamide gel, either BSV RNA-1 or RNA-2. No plant which has yet been detected contained both. No variation whatever was observed in the electrophoresis mobility, even over a period of two and a half years for BSV RNA-1 and RNA-2.The calli developed from diseased leaves grew rather slowly compared with healthy ones. The replication of BSV RNA-1 in calli which had continuously grown for 6—8 months was evidenced by the distinct band of BSV RNA-1 on file gels.     

Spurious symmetry-broken phase in a bidirectional two-lane ASEP with narrow entrances

As one of the paradigmatic models of non-equilibrium systems, the asymmetric simple exclusion process(ASEP) has been widely used to study many physical, chemical, and biological systems. The ASEP shows a range of nontrivial macroscopic phenomena, among which, the spontaneous symmetry breaking has gained a great deal of attention. Nevertheless,as a basic problem, it has been controversial whether there exist one or two symmetry-broken phases in the ASEP. Based on the mean field analysis and current minimization principle, this paper demonstrates that one of the broken-symmetry phases does not exist in a bidirectional two-lane ASEP with narrow entrances. Moreover, an exponential decay feature is observed,which has been used to predict the phase boundary in the thermodynamic limit. Our findings might be generalized to other ASEP models and thus deepen the understanding of the spontaneous symmetry breaking in non-equilibrium systems.