Functional sample path properties of subsequence's C-R increments for a Wiener process in Hlder norm

In this paper, with the aid of large deviation formulas established in strong topology of functional space generated by H¨older norm, we discuss the functional sample path properties of subsequence's C-R increments for a Wiener process in H¨older normThe obtained results,generalize the corresponding results of Chen and the classic Strassen's law of iterated logarithm for a Wiener process.     

基于碳量子点和罗丹明B的新型比率荧光试纸片检测水中Hg(Ⅱ)

水环境中Hg(Ⅱ)的污染对生态环境和人类健康危害极大，目前Hg(Ⅱ)的检测主要有原子光谱/质谱和电化学等方法，但存在检测仪器昂贵、操作繁琐及前处理复杂等缺点，难以在日常水环境中微量Hg(Ⅱ)现场检测的应用。因此，建立一种灵敏、准确、快捷和经济的水中Hg(Ⅱ)检测方法具有重要意义。试纸法是将普通的化学反应从玻璃仪器转移到试纸上进行的一种快速检测方法，利用试剂与目标物之间产生的化学反应，通过颜色的变化可对目标物进行定性或半定量检测，具有操作简便、快速等优点。碳量子点是一类粒径小于10 nm的碳基纳米材料，具有优异的荧光性能、较低的毒性和较高的化学稳定性。利用Hg(Ⅱ)对碳量子点的荧光具有灵敏和高效的猝灭作用，构建了一种双色比率荧光试纸片用于快速检测水中微量Hg(Ⅱ)的含量。其中，采用氮掺杂水溶性碳量子点（NCDs）作为荧光响应信号、罗丹明B（RhB）作为荧光内标信号，在单一波长（355 nm）激发下产生位于440和580 nm的双色荧光发射峰。当体系加入不同浓度Hg(Ⅱ)后，NCDs表面官能团与Hg(Ⅱ)之间的静电作用和金属配位协同作用使荧光发生猝灭，而RhB的荧光信号保持不变，利用440和580 nm双色荧光信号或其强度的比值（F₄₄₀/F₅₈₀），可实现对微量Hg(Ⅱ)的快速检测。实验对检测条件进行了优化，结果表明在HAc-NaAc缓冲液浓度为1 mmol·L-1、pH为7的条件下，F₄₄₀/F₅₈₀值与Hg(Ⅱ)浓度（0～3 μmol·L-1）呈现良好的线性关系，线性方程为F₄₄₀/F₅₈₀=-0.785 2ｃ_Hg(Ⅱ)+3.103 8，相关系数r＞0.99，以3倍标准偏差计算的检出限为2.7 nmol·L-1(n=9)。对湖水与自来水中Hg(Ⅱ)进行加标回收实验，其加标回收率在91.9%～117.9%之间，说明该方法灵敏、准确，能用于水中Hg(Ⅱ)的检测。同时，将NCDs和RhB浸渍于尼龙片上构建了双色比率荧光检测试纸片，在紫外灯（365nm）照射下可观测到试纸发射淡蓝紫色荧光。而随着Hg(Ⅱ)浓度的增加，荧光颜色从淡蓝紫色到橙色发生变化，每次检测时间只需3分钟，裸眼可检出Hg(Ⅱ)浓度低至10 nmol·L-1，实现了对水中微量Hg(Ⅱ)的灵敏、快速检测。此外，该方法对Hg(Ⅱ)的检测表现出良好的特异性。因此，基于碳量子点和罗丹明B构建的双色比率荧光试纸片具有携带方便、操作简单，以及灵敏和快速等优点，为水中微量Hg(Ⅱ)的快速检测提供了新的方法和思路。     

Tuning of Photonic band gap via combined effect of electric and optical fields in a blue phase liquid crystal composite

ABSTRACT

Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap.     

纳米光学传感器用于检测汞离子

汞离子是毒性最大的重金属之一,对环境和人体都会造成严重的不良影响,开发能够快速检测环境中汞离子的分析方法引起了越来越多的关注。纳米材料由于其优良的光学性能和良好的稳定性,被广泛用于环境中汞离子的检测。本文主要综述了近年来一些代表性的基于纳米材料的汞离子荧光、比色传感器。根据纳米材料的不同,将这些传感器分为基于金、银、碳和硅基材料,以及量子点、有机纳米颗粒和其他纳米基材料的荧光、比色传感器,并分别从设计原理、识别性能和实际应用等方面对这些传感器进行了描述和讨论。最后对该领域的研究和发展提出了展望。     

Recognition of dicarboxylates in aqueous acetonitrile by a dinuclear zinc(II) complex of 2,2’-binaphthalene-based receptor

Molecular recognition of dicarboxylates by a dinuclear zinc(II) complex of 2,2?-binaphthalene bearing di(2-pyridyl)aminomethyl groups at 8- and 8?-positions ([Zn₂L]⁴⁺) by UV-vis and fluorescence spectral titrations in an aqueous solvent was investigated. In a series of α,ω-dicarboxylate, receptor [Zn₂L]⁴⁺ showed the highest binding affinity for succinate and UV-vis and fluorescence changes were also largest upon the addition of this guest. In a series of phthalate derivatives, phthalate was strongly bound by [Zn₂L]⁴⁺. The characteristic UV-vis and fluorescence changes strongly depend on the dihedral angle of two naphthyl groups of the complex [Zn₂L]⁴⁺· dicarboxylate estimated by spectral titrations and DFT calculations.     

Quantum chemical studies on solvent effects,ligand–water complexes and dimer structure of 2,2ʹ-dipyridylamine

In this work, optimised structures, structural and spectroscopic properties of 2,2?-dipyridylamine (DPA) in solvent media have been investigated. Conformational structures of DPA were determined and relative population distributions of the conformations were obtained. Vibrational modes were calculated for each environment and they were compared with the experimental values. The effects of the changing solvent environments on the molecular structures were investigated and hydrogen bonded complex structures that DPA could form with water molecules were studied. As a result of this study, the effects of solvent environments on the molecular structure of DPA have been determined. Chemical reactivities of DPA which have not been studied previously have been determined. When the solid phase infrared spectrum of pure DPA was examined, it was seen that N-H stretching mode was observed at 3250 cm^?1. Since it will mean that there is bonded N-H in the structure, the dimer structure of DPA has been investigated.     

Dayaolingzhiols A−E,AchE inhibitory meroterpenoids from Ganoderma lucidum

Ganoderma mushrooms are widely used as effective medicines for treating and preventing chronic diseases. In this study, five new meroterpenoids, dayaolingzhiols A (1) and B (2) featuring a 6/6/6 ring system, dayaolingzhiols C?E (3–5) harboring a γ-lactone motif, along with eight known ones (6–13), were purified from G. lucidum. To clarify their chemical structures, spectroscopic and ECD and OR computational methods were used. In addition, the inhibition of all the new meroterpenoids against AChE was evaluated, disclosing that (+)-4 and (±)-5 possess potent AChE inhibitory activities with respective IC₅₀ values of 8.52?±?1.90?μM and 7.37?±?0.52?μM.