A Double-Site Chemodosimeter for Selective Fluorescence Detection of a Nerve Agent Mimic

A novel two-site chemodosimeter (SWJT-4) based on fluorescein skeleton to detect diethyl chlorophosphate (DCP) was designed and synthesized. It is a turn-on fluorescent probe for DCP with good selectivity and obvious color change in aqueous solution. Interestingly, the two oxime groups of SWJT-4 as dual response sites initiated different reactions with DCP to form a cyano group and an isoxazole ring, respectively. The corresponding mechanism was confirmed by 1H NMR, MS and DFT calculation. Moreover, SWJT-4 could be used as a fluorescent test paper to detect DCP vapor.

Research on English Online Test Platform Based on Real-Time Web Communication Technology

Due to the multiattribute and multi-related problems of the target English test platform, the efficiency of the platform is low. In order to solve the problem of insufficient control of the difficulty of the test questions in the process of English test paper generation, this paper designs an English test platform based on real-time network communication technology. The English test platform designed in this paper includes three modules: user management module, question bank management module, and test paper management module. Among them, in the test paper management module, we extract English test questions according to the test paper generation strategy, then use real-time web communication technology according to the test paper generation target, and, through effective update of pheromone, solve the problem of high test question repetition rate in automatic test paper generation and design the network. The self-learning platform and English test platform modules have completed the design of the English test platform based on real-time network communication technology. The experimental results show that the designed English test platform has a high success rate, quick test paper generation time, and good application value.

Synthesis of Symmetrical Acetophenone Azine Derivatives as Colorimetric and Fluorescent Cyanide Chemosensors

Cyanide is a highly toxic anion and poison to the environment. Therefore, fast, effective, and efficient analysis methods to detect cyanide are needed. Herein, symmetrical chemosensor of 2’-hydroxy acetophenone azine (1) and 2’,4’-dihydroxy acetophenone azine (2) has been synthesized tested as colorimetric and fluorescent cyanide chemosensor. The azines were produced from the condensation of acetophenone derivatives with hydrazine hydrate in ethanol under reflux or ultrasonic irradiation methods. Colorimetric and fluorescent chemosensor tests showed selectivity to acetate and cyanide anions in DMSO. The limit of detection (LOD) for colorimetric measurement of cyanide anion was 9.68×10–4 M for compound (1) and 9.63×10–5 M for compound (2), while the fluorescent method showed 15.90×10–4 M for compound (1) and 8.95×10–5 M for compound (2), respectively. In addition, test paper-strips containing sensor 2 indicated noticeable results for 'naked eye' detection of cyanide in an aqueous medium.

Rapid Detection of Chloramphenicol Residues in Fermented Foods Based on UPLC-DAD

in the detection of chloramphenicol residues in fermented food, there are often problems of slow detection speed. Using UPLC-DAD method, a rapid detection method of chloramphenicol residues in fermented food based on UPLC-DAD method is designed. According to the characteristics of chloramphenicol, set up the detection reagent, select the detection equipment, and form the detection laboratory. It is usingUPLC-DAD method to design the test paper, using the set test reagent to deal with the sample to be tested, according to the design results of the test process, combining the reagent with the sample, to determine its specificity. Chloramphenicol residue was detected by test paper. So far, the rapid detection method of chloramphenicol residues in fermented food based on UPLC-DAD method has been designed. Compared with the original detection method, the detection speed of the detection method designed in this paper is significantly higher than the original method. In conclusion, the rapid detection method of chloramphenicol residues in fermented food based on UPLC-DAD method is effective.

Facile and Sensitive Detection of Nitrogen-Containing Organic Bases with Near Infrared C-Dots Derived Assays

In this article, we have designed both colorimetric (including solution and test paper type) and spectral sensors (including UV-vis and PL type) for the quick and sensitive detection of general nitrogen-containing organic bases (NCOBs); the limit of detection could reach as low as 0.50 nM. NCOBs included 11 examples, covering aliphatic and aromatic amines, five- and six-membered heterocyclics, fused-ring heterocyclics, amino acids, and antibiotics. Furthermore, the assays demonstrated high reliability in sensing NCOBs and excellent ability to distinguish NCOBs from oxygen and sulfur containing organics. The assays developed could find important applications for the detection of NCOBs in the fields of biomedicine, chemistry, and agriculture.