Steady-state electrolysis at a grooved or ridged plane

This study concerns an infinite plane whose smoothness is marred by a single defect: either a groove or a ridge. The blemished plane serves as an electrode supporting a diffusion-controlled steady-state process. By using a convenient coordinate transformation, the local current density at all points on the surface is determined exactly. The results are found to confirm intuitive expectations. Thus, compared with normal values on the plane remote from a groove, the electron transfer rate is diminished within the groove but enhanced along its margins. Similarly, an abnormally large transfer rate is encountered high on the ridge but the rate is subnormal on its lower flanks. The total current is demonstrated to be unchanged by the presence of the blemish. Received: 27 September 1996 / Accepted: 11 March 1997     

Spectroscopic and Binding Properties of Berberine to DNA and Its Application to DNA Detection

Berberine(BER) binds to the double helical DNA with a high affinity There is only a much smaller hypochromism and no shifts in the absorption spectra when BER binds to calf thymus DNA(CT DNA) The fluorescence yields increase dramatically when BER binds to DNA, with no shifts in the emission maximum. These spectral changes are in contrast to the behavior observed with many fluorescent intercalates Groove binding rather than intercalation was suggested to be the cause of these spectral changes. Consistent with groove binding, for polyamide anion quenching studies showed that the magnitude of K_sv of the bound BER was higher than that of the free BER. The addition of salt to the solution releases the DNA-bound drug action from the groove and causes a decrease in the fluorescence yield. The results of all above studies proved the groove binding of BER to DNA. The large fluorescence enhancements observed when BER binds to DNA and the poor fluorescence yield of BER in the absence of DNA can be used for sensitive detection of DNA The linear concentration range was 0–20μg/ml The limit of detection for CT DNA was 12 ng/ml     

Sensitive Nucleic Acid Detection at NH2‐MWCNTs Modified Glassy Carbon Electrode and its Application for Monitoring of Gemcitabine‐DNA Interaction

An electrochemical dsDNA nanobiosensor was fabricated using amino‐functionalized multi walled carbon nanotubes modified glassy carbon electrode (NH₂fMWCNTs/GCE) for the sensitive detection of DNA bases and electrochemical monitoring of drug‐DNA interaction. The influence of functional groups on MWCNT was studied by MWCNT functionalized with NH₂ (NH₂fMWCNTs) and COOH (COOHfMWCNT) groups based on the signal of DNA bases. The modified electrodes were characterized by scanning electron microscopy. One layer of calf thymus double stranded deoxyribonucleic acid (ct‐dsDNA) was immobilized onto the NH₂fMWCNTs/GCE (dsDNA/NH₂fMWCNTs/GCE). The dsDNA/NH₂fMWCNTs/GCE were used to investigate the interaction between the dsDNA and the anticancer drug gemcitabine by differential pulse voltammetry in acetate buffer of pH 4.70. For the confirmation of interaction, the lowering in intensity of the current signals of guanine and adenine was considered as an indicator. Electrochemical impedance spectroscopy studies were performed for the comparison of the modified surfaces. In order to define and visualize the interaction mechanism between gemcitabine and dsDNA/NH₂fMWCNTs/GCE at the molecular level, in silico methods including docking and molecular dynamics simulations were employed.     

对称面形光栅TE模的衍射特性

本文采用耦合波方法计算了对称面形光栅的衍射效率,分析了光栅截面面形为正弦、三角形、矩形、梯形光栅衍射效率与光栅周期、沟槽深度的关系,计算了光栅的峰值衍射效率。理论计算表明:合理地选择光栅周期、沟槽深度,对称面形光栅都可以达到很高衍射效率,接近100%;光栅的峰值衍射效率基本出现在Bragg衍射且光栅的周期等于衍射波长时。     

采用边界元法研究槽形波导的色散特性

本文提出了用边界元法分析槽形波导的方法。推导出了有关表达式,并对一典型例子进行了研究,计算了其色散特性;得到的数据均与其它方法的结果相吻合。由于本文方法推导简单,计算省时,所以是研究此类问题的有效途径。     

射频功放板半金属化槽制作缺陷改善研究

射频功放类印制电路板常设计有半金属化槽作为埋制焊接功率放大器的配合空间,本文研究探讨了影响半金属化槽槽壁质量的各种因素。理论和实验两个角度分析验证了铣刀类型与走刀方向对半金属化槽披锋毛刺的影响,得出半金属化槽控深铣时平底型铣刀及逆铣方式更有利于槽壁质量。同时利用正交实验优化了半金属化槽铣槽制作参数,并提出了一种有利于改善槽壁披锋毛刺的新工艺流程。     

Synthesis,characterization and DNA interaction studies of a new platinum(II) complex containing caffeine and histidine ligands using instrumental and computational methods

A new Pt(II) complex, [Pt(Caff)(His)(Cl)] (Caff is Caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) and His is l-Histidine), was synthesized and characterized using different physicochemical methods. The interaction of this complex with calf thymus DNA (ct-DNA) was investigated by absorption, emission, circular dichroism (CD), and viscosity measurements and molecular docking techniques. The calculated binding constant, K_b, was 5.3 × 10³ M^?1. In fluorimetric studies, the enthalpy and entropy of the reaction between the complex and ct-DNA showed that the reaction is exothermic (?H = ?184.07 kJ mol^?1, ?S = ?551.97 J mol^?1 K^?1). CD spectra of DNA in the presence of different amounts of the complex showed little changes in both the negative and positive band intensities, which imply a non-intercalative mode between the DNA and the platinum complex. Furthermore, the study of molecular docking also indicated that the complex binds to DNA via a groove binding mode.     

渐近波形估计应用于地限大导体平面上凹槽散射场宽角度方向性函数的快速获取

本文基于渐近波形估计（AWE）技术和矩量法（MOM）快速预测无限大导体平面上任意形状凹槽的散射场方向性函数。用矩量法求解得到给定方向入射波照射下凹槽口径磁流,用AWE技术得到任意方向人射波照射下口径磁流,进而计算出散射场的方向性函数。计算结果表明AWE能逼近MOM计算结果,同时在计算速度上可提高几十倍。     

电子束曝光UV3正性抗蚀剂的工艺研究

为了在体硅CMOSFinFET中用等离子体腐蚀精细凹槽图形，研究了将电子束直写曝光用于原为深紫外光学曝光的UV3正性抗蚀剂的工艺技术；详细分析了包括膜厚、曝光能量、曝光剂量、显影时间、设计尺寸和衬底材料等在内的各类工艺参数与实际曝光图形效果的关系；特别指出了曝光过程中特有的延迟效应及解决办法。采用最终的优化工艺条件，得到了合适的图形效果。     

溴鼠灵与DNA作用机制的光谱研究

农用化学物质残留可能会与DNA结合形成加和物,从而对动物和人类造成危害。文章利用紫外光谱和荧光光谱研究了溴鼠灵(BDF)与小牛胸腺DNA(ct-DNA)的作用机理。结果表明,低浓度的ct-DNA可使BDF的吸收光谱发生减色,ct-DNA对BDF的稳态荧光有明显的的猝灭作用,属于静态猝灭方式,27 ℃时K_SV=1.21×104 L·mol-1;根据热力学参数推测BDF与ct-DNA之间的相互作用主要是范德瓦耳斯力作用;猝灭试验发现ct-DNA对BDF无明显保护作用;离子强度改变时,BDF/ct-DNA体系的荧光强度也随之改变;ct-DNA对β-CD/BDF包络物的荧光也有猝灭,但猝灭程度比游离的BDF有所降低,表明β-CD对BDF具有保护作用,也说明BDF与ct-DNA或β-CD的结合具有竞争性。各试验结果一致表明BDF与ct-DNA之间主要是以沟区结合方式发生作用。另外,试验结果也表明BDF与ct-DNA之间还存在静电作用。范德瓦耳斯力和静电作用的共同作用,为BDF在沟区与DNA的相互结合提供了更好条件。