激光诱导荧光探测水体中溶解有机物浓度

用Nd∶YAG激光器的三倍频355 nm光作为激发光源,根据激光诱导荧光(LIF)方法激发并探测污染水体的荧光光谱.通过对荧光光谱的分析处理研究归一化荧光强度,即450 nm处水中溶解有机物(DOM)峰与405 nm处水的拉曼峰的比值,反演溶解有机物浓度.用商品腐殖酸和去离子水配置成已知浓度的溶液代替标准DOM溶液进行标定,得到回归方程.结果证明,DOM的归一化荧光强度与水体中DOM浓度有较好的线性关系,因此LIF方法是对大面积水域水质进行动态遥测的较理想方法.     

Rapid Capillary-Assisted Solution Printing of Perovskite Nanowire Arrays Enables Scalable Production of Photodetectors

Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution-print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary-assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary-directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as-printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.     

共晶含能材料研究进展

共晶是不同种类的分子(两种或两种以上)通过氢键等分子间相互作用,形成具有特定结构和性能的多组分分子晶体,不同含能材料形成共晶可以有效改善炸药的感度、安全性等性能。针对目前高能炸药的改性需求,共晶在含能材料领域中的应用具有巨大的潜力。综述了共晶的形成原理及生长特性,总结了常见共晶的制备方法和表征方法,评述了含能材料共晶的研究现状和发展前景。     

米托蒽醌与B-DNA相互作用的分子模拟

针对嵌插型抗癌药物米托蒽醌(mitoxantrone,MTX)同B-DNA间作用模式的争议,采用分子模拟方法研究了米托蒽醌分子与B-DNA分子的相互作用.结果表明:米托蒽醌分子插入到B-DNA中有大小沟选择性及碱基对特异性,更倾向从小沟方向插入到DNA分子中;对5'-CG碱基对有特异性识别.通过详细能量项的分析,揭示了米托蒽醌插入DNA分子的驱动力及对碱基的特异性识别作用主要是空间相互作用特别是静电相互作用.在最佳作用位点复合物的构象分析则表明蒽醌环只有一部分插入碱基对中,侧链在小沟中延磷酸基骨架以3'-5'方向伸展,并通过静电作用进一步增强米托蒽醌与B-DNA的结合.     

Exploring Reversible Quenching of Fluorescence from a Pyrazolo[3,4‐b]quinoline Derivative by Protonation

Pyrazolo[3,4‐b]quinoline derivatives are reported to be highly efficient organic fluorescent materials suitable for applications in light‐emitting devices. Although their fluorescence remains stable in organic solvents or in aqueous solution even in the presence of H₂O, halide salts (LiCl), alkali (NaOH) and weak acid (acetic acid), it suffers an efficient quenching process in the presence of protic acid (HCl) in aqueous or ethanolic solution. This quenching process is accompanied by a change in the UV spectrum, but it is reversible and can be fully recovered. Both steady‐state and transient fluorescence spectra of 1‐phenyl‐3,4‐dimethyl‐1H‐pyrazolo‐[3,4‐b]quinoline (PAQ5) during quenching are measured and analyzed. It is found that a combined dynamic and static quenching mechanism is responsible for the quenching processes. The ground‐state proton‐transfer complex [PAQ5 ??? H⁺] is responsible for static quenching. It changes linearly with proton concentration [H⁺] with a bimolecular association constant K_S=1.95 M ^?1 controlled by the equilibrium dissociation of HCl in ethanol. A dynamic quenching constant K_D=22.4 M ^?1 is obtained by fitting to the Stern–Volmer equation, with a bimolecular dynamic quenching rate constant k_d=1.03×10⁹ s^?1 M ^?1 under ambient conditions. A change in electron distribution is simulated and explains the experiment results.