Online Flowing Colloidosomes for Sequential Multi‐analyte High‐Throughput SERS Analysis

3D plasmonic colloidosomes are superior SERS sensors owing to their high sensitivity and excellent tolerance to laser misalignment. Herein, we incorporate plasmonic colloidosomes in a microfluidic channel for online SERS detection. Our method resolves the poor signal reproducibility and inter‐sample contamination in the existing online SERS platforms. Our flow system offers rapid and continuous online detection of 20 samples in less than 5 min with excellent signal reproducibility. The isolated colloidosomes prevent cross‐sample and channel contamination, allowing accurate quantification of samples over a concentration range of five orders of magnitude. Our system demonstrates high‐resolution multiplex detection with fully preserved signal and Raman features of individual analytes in a mixture. High‐throughput multi‐assay analysis is performed, which highlights that our system is capable of rapid identification and quantification of a sequence of samples containing various analytes and concentrations.     

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg²⁺, Ca²⁺, and Sr²⁺ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV‐absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg²⁺, Ca²⁺, and Sr²⁺ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg²⁺, Ca²⁺, and Sr²⁺ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S /N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded.     

Effective length calibration method for processing the fluorescence signal detected by charge‐coupled device in capillary electrophoresis

A novel method named effective length calibration method has been developed to process the fluorescence signal detected by charge‐coupled device during capillary electrophoresis. The new method treated each pixel as an individual point detector, and effectively binned a large number of pixels into a final electropherogram without losing the narrow detection window defined by a single pixel. Capillary electrophoresis separations of DNA were carried out and detected by charge‐coupled device and conventional detector (photomultiplier tube). Detection properties including signal‐to‐noise ratio, peak width, detection frequency, and tilt of detector were investigated. It was found that the new method achieved much higher signal‐to‐noise ratio and smaller peak width than the conventional detector did. A Detection width of 0.5 μm was easily achieved.     

Synthesis of Cu2O/Ag Composite with Visible Light Photocatalytic Degradation Activity for in situ SERS Analysis

A multifunctional Cu₂O/Ag micro-nanocomposite, which has the characteristics of high catalytic activities under the visible light and high surface-enhanced Raman scattering (SERS) activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO₃ concentration, Ag content on the Cu₂O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanoparticles form on the Cu₂O nanoframes to obtain the Cu₂O/Ag nanocomposite, which can act as an excellent bifunctional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS.     

Naked-eye detection of cyanide ions in aqueous media based on an azo-azomethine chemosensor

The optical and colorimetric properties of a new chemosensor 4-((2,4-dichlorophenyl)diazenyl)-2-(3-hydroxypropylimino)methyl)phenol (L) for cyanide ions were investigated by the naked-eye detection and UV–vis spectroscopy. This receptor reveals visual changes toward CN⁻ anions in aqueous media. No significant color changes were observed upon the addition of any other anions. The cyanide recognition properties of the receptor through proton-transfer were monitored by UV–vis titration and ¹H NMR spectroscopy. The binding constant (K_a) and stoichiometry of the formed host–guest complex were calculated by the Benesi–Hildebrand (B–H) plot and Job's plot method, respectively. The detection limit of the probe towards CN⁻ was 1.03 × 10⁻⁶ mol L⁻¹, which is lower than the maximum value of cyanide (1.9 × 10⁻⁶ mol L⁻¹) permitted by the World Health Organization in drinking water. Thus, this chemosensor was sensitive enough to detect cyanide in aqueous solutions. ¹H NMR experiments were conducted to investigate the nature of interaction between the receptor and CN⁻ anions. Notably, the designed sensor can be applied for the rapid detection of cyanide anions in the basic pH range and also under physiological conditions, for practical purposes for a long duration. The sensing behavior of the receptor was further emphasized by computational studies. Quantum-chemical calculations and molecular studies via Density Functional Theory (DFT) were carried out to supplement the experimental results.     

Wavelet-based estimator for the hurst parameters of fractional brownian sheet

It is proposed a class of statistical estimators H =(H_1,…,H_d) for the Hurst parameters H =(H_1,…,H_d) of fractional Brownian field via multi-dimensional wavelet analysis and least squares,which are asymptotically normal.These estimators can be used to detect self-similarity and long-range dependence in multi-dimensional signals,which is important in texture classification and improvement of diffusion tensor imaging(DTI) of nuclear magnetic resonance(NMR).Some fractional Brownian sheets will be simulated and the simulated data are used to validate these estimators.We find that when H_i ≥ 1/2,the estimators are accurate,and when H_i 1/2,there are some bias.     

基于Hilbert变换的LFM检测与估计

LFM(线性调频)信号是一类重要的非平稳信号,其完全被初始频率和调频斜率两个参量表征,而LFM信号的检测与估计问题是信号处理中最为重要的研究热点之一.由于调频信号在时频平面内有较好的聚集性,通常使用时频分析的方法对其进行检测和估计.线性正则变换是经典时频分布的广义形式,对LFM信号具有很好的能量聚集特性,在现有的线性正则域Hilbert变换的基础上,提出了一种不需要谱峰搜索而快速检测LFM信号和估计其参数的方法,并且通过仿真实例验证了所提出方法的优越性.     

Viskositätsmessung mit dem longitudinal schwingenden Band

A method for the detection of small masses with the aid of a longitudinally vibrating band is described and further applications, e.g. for viscosity and humidity measurement are discussed. The complex Young's modulus of the band can also be determined.

     

容错信息融合滤波算法的研究

本文针对容错组合导航的特点，提出一种新的信息融合滤波算法，该算法既能提高系统的容错性能，使系统具有良好的实时故障检测、隔离和重构的能力，又能使系统出现故障时，重构的系统由于获得了融合的系统信息，以较高的精度工作。文中证明该算法与集中卡尔曼滤波器等效，因而是最优的。     

SINS/GPS/DVL组合导航系统的容错研究

结合SINS／GPS／DVL组合导航系统各子系统的特点，提出了一种新的容错设计方案。此方案采用并列运行的滤波器族结构，该结构可以提供不受污染的最优解，且具有容错性好和系统输出数据热备份等优点。仿真结果表明，此方案既可有效地监测和隔离系统故障，同时保证了系统的精度。