Template Synthesis and UV-Vis Absorption Spectra of the Nanowire Arrays of Cadmium Chalcogenides

以多孔氧化铝为模板 ,用交流电分别通过含有相应的CdCl2 、ZnCl2 、单质S、Se等的二甲亚砜 (DMSO)溶液 ,沉积CdS、CdSe以及CdxZn1-xS半导体纳米线阵列并研究其紫外可见吸收光谱 .实验结果表明 ,当半导体纳米线的直径小于 2 5nm时 ,其吸收边相对于体相的吸收边产生蓝移 ,而且蓝移的幅度随着半导体纳米线直径的减小而增加 ,显示了明显的量子限域效应 .XU Shi_min, XUE Kuan_hong , KONG Jing_lin, SUN Dong_mei, FENG Yu_ying, LU Hai_yan (Dept. of Chem., Nanjing Normal Univ., Nanjing 210097, China) WANG Guang_hou (National Laboratory of Solid State Microstructures, Nanjing Univ., Nanjing 210093, China)The porous alumina membrane formed in the anodic oxidation of highly pure aluminum foil has attracted a great deal of attention in recent years [1] . It can be served as a desired template to prepare nanometer scale materials [2] due to its unique structure of discrete and cylindrical nanopores, paralleled one another, with the homogeneous size and distribution [3] . Chalcogenide semiconductors have promising prospect in the applications of photovoltaic [4] and photoconducting devices [5] and have been extensively exploited for many years. Olbright and his co_workers studied experimentally and theoretically the optical nonlinearties of CdS xSe 1-x _doped glass [6] ; Britt and Ferekides reported that the conversion efficiency in a solar cell of thin_film CdS/CdTe could be as high as 15.8% [7] . Here we report the fabrication and UV_Vis absorption spectra of CdS、CdSe and Cd xZn 1-x S nanowire arrays deposited into the template matrix of porous alumina. The diameters of these nanowires were varied from 10 nm to 50 nm in our experiments.作者联系地址：南京师范大学化学系!江苏南京210097,南京师范大学化学系!江苏南京210097,南京师范大学化学系!江苏南京210097,南京师范大学化学系!江苏南京210097,南京师范大学化学系!江苏南京210097,南京师范大学化学系!江苏南京210097,南京大学固体微结构国家重点实验室!江苏南京21009

烟草NtFtsZ2-1基因在叶绿体分裂中的作用机制研究及NtFtsZ1-2基因启动子的克隆

根癌农杆菌通过将一段含有“癌”基因的T-DNA导入植物基因组中，引起植物的肿瘤：冠瘿。根癌农杆菌的这种能力来源于Ti质粒（Tumor inducing plasmid）。遗传工程中，根癌农杆菌的这一特性被用来将连接入Ti质粒T-DNA区两个边界之间的外源基因转入植物基因组。随着植物分子生物学的发展，T-DNA转化的原理被进一步阐明，农杆菌介导的转基因技术也得到进一步优化，更适合遗传工程操作。特别是Ti质粒毒性区和T-DNA区的反式作用（即位于不同质粒的T-DNA和毒性区也能侵染植物）被发现以来，双元表达载体的构建使遗传工程操作大为简便。 常用的双元表达载体大小都在11kb以上，尽管远远小于几百kb的野生型Ti质粒，但在实际的体外操作中还是不够简便。常用的植物双元表达载体pBI121的基因序列被测定（Frisch et al.，1995），数据显示非T-DNA区一半以上的序列被发现和功能无关，这使双元载体的进一步缩小成为可能。本文即通过PCR方法克隆到pBI121非T-DNA区中载体复制、三亲杂交必需的片段，结合载体pART27中的T-DNA区（含有真核、原核表达活性的嵌合npt II基因）创造了小的合成型植物表达双元载体pSY1（小于7kb）。然后将pBI121上带有35S启动子和nos终止子的GUS基因克隆到pSY1的T-DNA区中，得到pSY2（约10kb）。进一步用pROK2上的35S启动子和nos终止子区替换pSY2上的GUS表达区，得到pSY3（约8kb）。通过三亲法将pSY2转入根癌农杆菌中，根癌农杆菌再通过叶盘法侵染烟草叶片，获得愈伤组织，愈伤组织进一步分化出小苗。GUS组织化学染色表明GUS基因在转基因的愈伤组织和小苗中均有表达，PCR检测也证明GUS基因被导入了植物基因组。pSY系列载体能成功的用于植物遗传转化

螺旋板式潜热储热器内二维相变与对流藕合传热问题的近似解法

本文就作者提出的螺旋板式相变储热装置进行了研究。建立了其瞬态换热过程的数学模型，并用准稳态法首次求得了关于实际装置的二维凝固与强迫对流耦合问题的近似解。该解能方便处理变流体进口温度的情形，求解耗时甚少从而克服了数值法计算量过大的缺点。在用等效导热系数法处理液相区内自然对流的影响后，该解可有效地推广至融化换热过程。实验结果表明，理论解与实验值有较好的一致，从而证明理论的正确性及有效性。本文还利用所建立的理论模型研究了流体流量、进口温度与相变点的差值、螺旋圈数及螺旋通道相变材料侧宽度等参数对装置换热性能的影响，为装置的优化设计提供了理论指导

细胞粘附力敏感性的微观力学模型

Focal adhesions(FAs)are large,multiprotein complexs that provides linkers between cytoskeleton to the extracellular matrix(ECM).Cells sense and respond to forces throug

Stabilizing to disruptive transition of focal adhesion response to mechanical forces

Strong mechanical forces can, obviously, disrupt cell-cell and cell-matrix adhesions, e.g., cyclic uniaxial stretch induces instability of cell adhesion, which then causes the reorientation of cells away from the stretching direction. However, recent experiments also demonstrated the existence of force dependent adhesion growth (rather than dissociation). To provide a quantitative explanation for the two seemingly contradictory phenomena, a microscopic model that includes both integrin-integrin interaction and integrin-ligand interaction is developed at molecular level by treating the focal adhesion as an adhesion cluster. The integrin clustering dynamics and integrin-ligand binding dynamics are then simulated within one unified theoretical frame with Monte Carlo simulation. We find that the focal adhesion will grow when the traction force is higher than a relative small threshold value, and the growth is dominated by the reduction of local chemical potential energy by the traction force. In contrast, the focal adhesion will rupture when the traction force exceeds a second threshold value, and the rupture is dominated by the breaking of integrin-ligand bonds. Consistent with the experiments, these results suggest a force map for various responses of cell adhesion to different scales of mechanical force. PMID: 2054251