基于三维荧光光谱的克百威农药含量的检测方法

农药的广泛使用是防治病虫害的一种必要手段,在保证农业增产增收的同时,也给人们健康带来了威胁,寻求更加灵敏的农药残留检测方法至关重要。三维荧光光谱分析法选择性好、灵敏度高、快捷、取样少,可用于农药残留的分析与检测中。以自制标准浓度的克百威农药溶液作为测试样本,乙腈为溶剂,利用荧光光谱仪对样本进行测量,将实验获得的三维数据用MATLAB进行处理获得其三维荧光光谱图。实验发现乙腈作为溶剂对实验影响不大且荧光光谱的强度与克百威溶液浓度呈现良好的线性关系,相关系数r=0.997 4,接近于1。因此三维荧光光谱分析法可以检测出克百威溶液的浓度以及农药的含量。     

氢化物-原子荧光法测定粮食中的砷

研究了氢化物－原子荧光法测定粮食中砷的适宜条件,试验了酸介质和还原剂的用量对测定砷的影响,选择了仪器的最佳工作条件及氢化物发生条件,试验了生成氢化物元素及粮食中常见元素对测定的干扰情况。在测定条件下,砷的线性范围为０～８０μｇ／Ｌ,检出限为０．３μｇ／Ｌ。用该法测定了标准物质小麦粉及大米,结果与推荐值吻合。方法快速、准确,应用于进口粮食中砷的检测,获得满意结果     

近红外光谱图像处理的霉变稻谷检测方法

稻谷在储藏和运输过程中,在适宜的温湿度环境下极易发生霉变,导致大量的粮食浪费和巨大的经济损失,进而影响粮食安全.为解决传统的稻谷霉变检测存在的繁琐且耗时较长等不足,提出了基于近红外光谱图像处理和神经网络的稻谷霉变程度检测方法.首先,通过农业多光谱相机(Sequoia)和固定光源等设备,构建了霉变稻谷近红外图像数据采集平...     

基于金属有机骨架材料的生物传感器在食源性致病菌或毒素检测中的应用

食源性致病菌或其产生的毒素污染的食物会给人体健康带来严重威胁,并造成巨大的经济损失。近年来,金属有机骨架材料(MOFs)作为一种新型的多孔晶体材料,因其具有大的表面积、高的孔隙率等特点,受到人们的广泛关注。将MOFs与生物传感器结合用于食源性致病菌或毒素的检测引起了研究者的兴趣。基于此,本文介绍了MOFs用于生物传感器的优势,概述了MOFs在不同的电化学和光学生物传感器的应用,综述了基于MOFs的生物传感器在致病菌或毒素的研究进展,讨论了基于MOFs的生物传感器在致病菌或毒素所面临的挑战和展望。     

Bright Free-Radical Emission in Ionic Liquids

It is challenging to achieve stable and efficient radical emissions under ambient conditions. Herein, we present a rational design strategy to protect photoinduced carbonyl free radical emission through electrostatic interaction and spin delocalization effects. The host-guest system is constructed from tricarbonyl-substituted benzene molecules and a series of imidazolium ionic liquids as the guest and host, respectively, whereby the carbonyl anion radical emission can be in situ generated under the light irradiation and further stabilized by electrostatic interaction. More importantly, the anion species and the alkyl chain length of imidazolium ionic liquids show a noticeable effect on luminescence efficiency, with the highest radical emission efficiency is as high as 53.3 % after optimizing the imidazole ionic liquid's structure, which is about four times higher than the polymer-protected radical system. Theoretical calculations confirm the synergistic effect of strong electrostatic interactions and that the spin delocalization effect significantly stabilizes the radical emission. Moreover, such a radical emission system also could be integrated with a fluorescent dye to induce multi-color or even white light emission with reversible temperature-responsive characteristics. The radical emission system can also be used to detect different amine compounds on the basis of the emission changes and photoactivation time.     

Hydrogen Bonds Strengthened Metal-Free Perovskite for Degradable X-ray Detector with Enhanced Stability,Flexibility and Sensitivity

Metal-free perovskites (MFPs) with flexible and degradable properties have been adopted in flexible X-ray detection. For now, figuring out the key factors between structure and device performance are critical to guide the design of MFPs. Herein, MPAZE-NH₄I₃ ⋅ H₂O was first designed and synthesized with improved structural stability and device performance. Through theoretical calculations, the introducing methyl group benefits modulating tolerance factor, increases dipole moment and strengthens hydrogen bonds. Meanwhile, H₂O increases the hydrogen bond formation sites and synergistically realizes the band nature modulation, ionic migration inhibition and structural stiffness optimization. Spectra analysis also proves that the improved electron-phonon coupling and carrier recombination lifetime contribute to enhanced performance. Finally, a flexible and degradable X-ray detector was fabricated with the highest sensitivity of 740.8 μC Gy_air⁻¹ cm⁻² and low detection limit (0.14 nGy_air s⁻¹).     

超氧阴离子

介绍了超氧阴离子 O-·2 的产生、检测、化学性质、反应动力学、生物学研究、应用等方面的研究进展。     

基于纳米金的ATP检测体系的研究进展

ATP是机体代谢过程中不可或缺的能量物质，参与机体的各项重要的生理生化活动，在各方面起着至关重要的作用。因此，对ATP的快速精准检测具有重要的临床意义。纳米金（AuNPs）因优良的光学特性、催化活性、生物相容性等特点，被广泛应用于构建ATP检测体系。本文综述了目前AuNPs应用于ATP检测的研究进展，如比色检测、荧光分析、电化学检测、电化学发光检测、化学发光检测以及表面增强拉曼散射等，比较了各种检测方法的优点与不足，并对AuNPs在ATP检测应用中面临的挑战和机遇做了展望。     

Unprecedented Relaxivity Gap in pH-Responsive FeIII-Based MRI Probes

Two mononuclear ferric complexes are reported that respond to a pH change with a 27- and 71-fold jump, respectively, in their capacity to accelerate the longitudinal relaxation rate of water-hydrogen nuclei, and this starting from a negligible base value of only 0.06. This unprecedented performance bodes well for tackling the sensitivity issues hampering the development of Molecular MRI. The two chelates also excel in the fully reversible and fatigue-less nature of this phenomenon. The structural reasons for this performance reside in the macrocyclic nature of the hexa-dentate ligand, as well as the presence of a single pendant arm displaying a five-membered lactam or carbamate which show (perturbed) pK_a values of 3.5 in the context of this N6 N5O1 coordination motif.     

Towards Electrochemiluminescence Microscopy Exploration of Plasmonic-Mediated Phenomena at the Single-Nanoparticle Level

The rational design of functional plasmonic metasurfaces and metamaterials requires the development of high-throughput characterization techniques compatible with operando conditions and capable of addressing single-nanostructures. In their work, Wei et al. demonstrate the use of electrochemiluminescence microscopy to investigate the mechanism behind plasmon-enhanced luminescence induced by gold nanostructures. The use of gold plasmonic arrays was exploited to achieve the rapid spectroscopic evaluation of all the individual nanostructures, and the correlation of the results with high- resolution electron microscopy analysis, guaranteeing a strict one-to-one correspondence. The authors were able to identify two different mechanisms for the enhancement of [Ru(bpy)₃]²⁺-tri-n-propylamine electrochemiluminescence mediated by single gold nanoparticles and by small plasmonic clusters. In the future, the proposed characterization could be used for the rapid and in situ spectroscopic analysis of more complex plasmonic nanostructures and metasurfaces.