AQC柱前衍生反相高效液相色谱法测定土壤中氨基酸

以2-氨基丁酸为内标物,6-氨基喹啉基-N-羟基琥珀酰亚氨基甲酸酯(AQC)为柱前衍生试剂,用XTerraC18柱,1.8mmol/L甲酸铵溶液(pH=3.0)和乙腈为流动相,采用梯度洗脱,光电二极管(PDA)检测器在248nm波长处检测,建立了一种利用反相高效液相色谱同时测定土壤中17种氨基酸的分析方法。方法重现性好,精密度高,氨基酸浓度在25~600μmol/L范围内,线性相关系数均大于0.99;各氨基酸检出限≤0.5pmol。并且在该色谱条件下,获得了灵敏度较高,彼此分离良好的17种AQC衍生氨基酸的LC-MS质谱总离子流图,为今后土壤氨基酸的深入研究提供了更加有利的手段。     

Tetra‐ammonium Zinc Phthalocyanine to Construct a Graded 2D–3D Perovskite Interface for Efficient and Stable Solar Cells

The crystallographic defects inevitably incur during the solution processed organic‐inorganic hybrid perovskite film, especially at surface and the grain boundaries (GBs) of perovskite film, which can further result in the reduced cell performance and stability of perovskite solar cells (PSCs). Here, a simple defect passivation method was employed by treating perovskite precursor film with a hydrophobic tetra‐ammonium zinc phthalocyanine (ZnPc). The results demonstrated that a 2D‐3D graded perovskite interface with a capping layer of 2D (ZnPc)_0.5MA_n ? 1Pb_nI_3n + 1 perovskite together with 3D MAPbI₃ perovskite was successfully constructed on the top of 3D perovskite layer. This situation realized the efficient GBs passivation, thus reducing the defects in GBs. As expected, the corresponding PSCs with modified perovskite revealed an improved cell performance. The best efficiency reached 19.6%. Especially, the significantly enhanced long‐term stability of the responding PSCs against humidity and heating was remarkably achieved. Such a strategy in this work affords an efficient method to improve the stability of PSCs and thus probably brings the PSCs closer to practical commercialization.     

基于菁染料响应G-四链体结构变化的半胱氨酸检测探针

半胱氨酸是生物体中起着重要作用的还原性氨基酸,其在体内的含量变化可能会诱发机体发生多种病变。因此高选择性、高灵敏度和低成本的半胱氨酸检测技术具有重要意义。目前,高效的半胱氨酸检测方法有毛细管电泳、质谱、高效液相色谱和表面增强拉曼散射等,这些方法往往需要复杂的样品制备和精细的实验仪器,可能会限制其在半胱氨酸检测中的应用。本文利用富含鸟嘌呤的DNA链序列在钾、钠等金属离子诱导下形成对汞离子产生特殊响应的二级结构,而菁染料能够对DNA结构进行识别,并由此引起其超分子聚集形式的改变,致使其紫外和可见光谱性质随之变化。最终以Hg²⁺调控G-四链体与菁染料(ETC)组建的传感器,实现对溶液体系中半胱氨酸高选择性的快速可视化检测。     

Monodentate AIEgen Anchored on Metal‐Organic Framework for Fast Fluorescence Sensing of Phosphate

Herein, a novel sensor (TPE‐UiO‐66) was designed via anchoring monodentate tetraphenylethylene (TPE) onto UiO‐66 framework. The combination of the distinct aggregation‐induced emission (AIE) of TPE and the easy replacement of monodentate linker by guest phosphate, makes TPE‐UiO‐66 an ideal platform for sensing HPO₄^2–. Experimental results indicate that TPE‐UiO‐66 can selectively sense HPO₄^2– from other common anions. The limit of detection (LOD) can reach to 5.56 μmol·L^–1 and more importantly, TPE‐UiO‐66 also exhibits an ultra‐fast equilibrium response of 2 min, far faster than those of other sensors especially for UiO‐66‐NH₂. The combination of experimental analysis and density functional theory (DFT) calculations demonstrates that the high selectivity, high sensitivity and fast response of HPO₄^2– detection by TPE‐UiO‐66 can be attributed to the stronger coordination interactions of HPO₄^2– with Zr‐O cluster of UiO‐66 than that of TPE molecule. This study not only provides a potential probe for phosphate, but also represents a novel strategy to design stimuli‐responsive fluorescent MOF‐based sensors via using monodentate AIEgens.     

Enhanced electrochemical performance of SnS nanoparticles/CNTs composite as anode material for sodium-ion battery

SnS/CNTs composite as anode for SIBs exhibits high reversible capacity, good cyclability as well as rate performance, which is superior to that of pure SnS. The enhanced electrochemical performance can be attributed to the adding of CNTs as a flexible and conductive structure supporter and the formation of SnS nanoparticles with small diameter.     

Silver nanocomposite layer-by-layer films based on assembled polyelectrolyte/dendrimer

Silver nanocomposite multilayer films were prepared through the in situ method. Multilayer thin films, prepared through the sequential electrostatic deposition of a positively charged third-generation poly(amidoamine) dendrimer (PAMAM) and negatively charged poly(styrenesulfonate) (PSS) and poly(acrylic acid) (PAA), were utilized as nanoreactors for the formation of silver nanoparticles. The silver ions were preorganized in layer-by-layer (LBL) films composed of PAMAM dendrimers and subsequently reduced with hydrogen to prepare the silver nanoparticles. The UV-vis spectrum and profilometer were used to characterize the regular growth of bilayers. UV-vis absorption from plasmon resonance at 435 nm and TEM images indicated the formation of the silver nanoparticles in the multilayer films. The silver nanocomposite LBL films were also constructed on the indium tin oxide-glass and investigated using cyclic voltammetry. The silver nanoparticles in the multilayer films have a stronger negative redox potential. The silver nanocomposite LBL films may have a potential application in the catalysis of reduction of 4-nitrophenol with sodium borohydride.     

Microfluidic differential resistive pulse sensors

This study demonstrates an on-chip resistive pulse-sensing scheme with a design of symmetric mirror channels, which significantly reduces the noise and achieves better signal-to-noise ratio. Polystyrene particles of different sizes have been detected with the developed sensing scheme and a record low volume ratio of the particle to the sensing channel, or 0.0004%, has been detected with particles of 520 nm in diameter in a sensing aperture of 50x16x20 microm3. This volume ratio is about ten times lower than the lowest volume ratio reported in the literature including that specified for commercial Coulter counters.     

低浓度固液两相流的颗粒相动理学模型

用广义Fokker-Planck扩散模型描述液相湍动对颗粒的挟带作用，用修正的BGK模型描述粒间碰撞效应，建立了封闭的颗粒相PDF输运方程．运用Chapman-Enskog迭代法求得方程的二阶近似解，获得颗粒相脉动速度二阶矩和三阶矩闭合关系．模型与颗粒流模型相容，与液相湍流闭合模型是否相容依赖于扩散模型的具体形式，并据此比较了不同的涡一颗粒作用模型．模型与二维明渠流轻质沙和天然沙试验资料符合很好．表明细小粒径颗粒能够充分跟随水流运动；大粒径颗粒的相间平均速度差和壁面滑移速度明显，近壁区内的颗粒沿流向和垂向脉动强度都可能大于水流，并存在一定程度的颗粒碰撞效应．     

Improvement of the Performance of an Acousto-Optical Q-Switched Nd:YAG 946 nm Laser Using a Convex–Plane Cavity

We improve the performance of an acousto-optical Q-switched Nd:YAG 946 nm laser using a convex–plane cavity. We obtain the highest output average power of 2.3 W with a pulse width of 15.3 ns in a 10 kHz 946 nm laser with a convex–plane cavity. The maximum peak power 15.0 kW is about three times higher than that in a plane–plane cavity. Also we investigate the output performances of the pulsed 946 nm laser with the convex–plane cavity at 20 and 50 kHz.     

Design of Two Pyrazole-Based Sensors with Similar Configuration and Different Fluorescent Response to Anions

Two simple fluorescent anion receptors based on 1-phenyl-3-methylpyrozole-5-one-4-one phenylhydrazone (L1) and 1-phenyl-3-methylpyrozole-5-one-4-one p-nitrophenylhydrazone (L2) were designed, synthesized and characterized with ¹H NMR, COSY spectrum, ¹³C NMR, ESI-mass and elemental analyse. Interestingly, two receptors with similar configuration exhibited different anion binding behaviors in DMSO solution. The results of Job plots and ESI-mass spectrum indicate that L1 bind anions such as F⁻, AcO⁻, H₂PO₄⁻ to form 2:1 host-guest complexation, while L2 bind anions to form 1:1 host-guest complexation in the solution.