Study on Rapid Detection of Pesticide Residues in Shanghaiqing Based on Analyzing Near-Infrared Microscopic Images

Aiming at guiding agricultural producers to harvest crops at an appropriate time and ensuring the pesticide residue does not exceed the maximum limit, the present work proposed a method of detecting pesticide residue rapidly by analyzing near-infrared microscopic images of the leaves of Shanghaiqing (Brassica rapa), a type of Chinese cabbage with computer vision technology. After image pre-processing and feature extraction, the pattern recognition methods of K nearest neighbors (KNN), naïve Bayes, support vector machine (SVM), and back propagation artificial neural network (BP-ANN) were applied to assess whether Shanghaiqing is sprayed with pesticides. The SVM method with linear or RBF kernel provides the highest recognition accuracy of 96.96% for the samples sprayed with trichlorfon at a concentration of 1 g/L. The SVM method with RBF kernel has the highest recognition accuracy of 79.16~84.37% for the samples sprayed with cypermethrin at a concentration of 0.1 g/L. The investigation on the SVM classification models built on the samples sprayed with cypermethrin at different concentrations shows that the accuracy of the models increases with the pesticide concentrations. In addition, the relationship between the concentration of the cypermethrin sprayed and the image features was established by multiple regression to estimate the initial pesticide concentration on the Shanghaiqing leaves. A pesticide degradation equation was established on the basis of the first-order kinetic equation. The time for pesticides concentration to decrease to an acceptable level can be calculated on the basis of the degradation equation and the initial pesticide concentration. The present work provides a feasible way to rapidly detect pesticide residue on Shanghaiqing by means of NIR microscopic image technique. The methodology laid out in this research can be used as a reference for the pesticide detection of other types of vegetables

Supplemental Material - Transferring near infrared spectral calibration models without standards via multistep wavelength selection

Supplemental Material for Transferring near-infrared spectral calibration models without standards via multistep wavelength selection by Lijun Ni, Zhange Zhang, Liguo Zhang and Shaorong Luan in Journal of Near Infrared Spectroscopy</p

Electric Papers of Graphene-Coated Co₃O₄ Fibers for High-Performance Lithium-Ion Batteries

A facile strategy to synthesize the novel composite paper of graphene nanosheets (GNS) coated Co₃O₄ fibers is reported as an advanced anode material for high-performance lithium-ion batteries (LIBs). The GNS were able to deposit onto Co₃O₄ fibers and form the coating via electrostatic interactions. The unique hybrid paper is evaluated as an anode electrode for LIBs, and it exhibits a very large reversible capacity (∼840 mA h g^–1 after 40 cycles), excellent cyclic stability and good rate capacity. The substantially excellent electrochemical performance of the graphene/Co₃O₄ composite paper is the result from its unique features. Notably, the flexible structure of graphenic scaffold and the strong interaction between graphene and Co₃O₄ fibers are beneficial for providing excellent electronic conductivity, short transportation length for lithium ions, and elastomeric space to accommodate volume varies upon Li⁺ insertion/extraction

Real-Time Monitoring of Translocation, Dissipation, and Cumulative Risk of Maleic Hydrazide in Potato Plants and Tubers by Ion Exclusion Chromatography

In this paper, a high-performance ion exclusion chromatographic (ICE) method was developed and applied for monitoring maleic hydrazide (MH) translocation in complex potato plant tissue and tuber matrices. After middle leaf uptake, most MH was trapped and dissipated in the middle leaf, and the rest was transported to other parts mainly through the phloem. Soil absorption significantly reduced the uptake efficiency of the root system, in which MH was partitioned to dissipate in root protoplasts or transfer through the xylem and persisted in the plant. Tuber uptake enabled MH to remain in the flesh and maintain stable levels under storage conditions, but during germination, MH was translocated from the flesh to the growing buds, where it dissipated through the short-day photoperiodic regime. The results demonstrated successful application of the ICE method and provided necessary insights for real-time monitoring of MH translocation behavior to effectively improve potato edible safety