With chitosan, nano-TiO2and nano-Ag as raw materials, nano-TiO2and nano-TiO2-Ag were modified by a surface modifier-sodium laurate. Chitosan (CTS), chitosan-nano-TiO2(CTS-TiO2), and chitosan-nano-TiO2-nano-Ag (CTS-TiO2-Ag) composite materials and corresponding films were prepared by a solution co-blending method. Then, the antibacterial performances of the above three types of materials againstEscherichia coli,Staphylococcus aureus, andBacillus subtiliswere compared. Moreover, potato and strawberry weight loss rates, peroxidase activity, and vitamin C contents after different film coating treatments were measured. Compared with CTS films, the CTS-TiO2-Ag and CTS-TiO2composite films both showed better physical properties, and both demonstrated higher antibacterial effects, especially forE.coli. Measurement of physiological indices in fruits and vegetables showed that the freshness-preserving effect of CTS-TiO2-Ag coating films was the most significant. In all, the CTS-TiO2-Ag coating films can actively contribute to the storage of fruits and vegetables at room temperature, and better ensure product quality. Thus, such films are meaningful for research and development of new fruit freshness-keeping techniques and materials.
Surfactants are known to enhance the degradation of halogenated organics by nanoscale zerovalent iron (n-ZVI) or n-ZVI-based bimetallic particles, but the mechanism of the promotion is not well understood. In this study, we used nanoscale Ag/Fe particles (n-Ag/Fe) to degrade 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in different surfactant solutions. The results show that the nonionic surfactant TX-100 had the best promoting effect, which might be attributed to the decrease in particle agglomeration and improvement of mass transfer efficiency after the adsorption of TX-100 on n-Ag/Fe. The distribution analysis of BDE-47 in solid and liquid phases indicates that when the concentration of TX-100 in aqueous solution was above critical micelle concentration, BDE-47 started to dissolve in the liquid phase. Thus, TX-100 micelles can enhance the mass transfer efficiency of BDE-47. However, a too high concentration of TX-100 (above 1.0 mM) would influence the promotion effect of BDE-47 degration, which might be attributed to the excessive and thicker micelles of TX-100 hindering the contact between BDE-47 and n-Ag/Fe. We also studied the degradation pathway of BDE-47 and its products, and found that surfactants did not change the degradation pathway of BDE-47.
Man Wang,Xuefeng Xu,Bing Ma,Yanyan Pei,Changchun Ai,Liangjie Yuan
Here we present a cheap alternative for the fabrication of conductive line patterns printed on a flexible PI substrate at intermediate temperature. In order to achieve this purpose, a low-cost and water-soluble screen printing conductive paste was prepared, with micron-SiO2@nano-Ag particles as the conductive filler. Variations in the filling content of micron-SiO2@nano-Ag, the addition of the coupling agent, curing temperature and time can remarkably affect the electrical and mechanical performance of the conductive paste. The optimal sheet resistance (at 62 mΩ □−1) and mechanical performance of the paste were achieved under the curing conditions of 140 °C for 30 min, with the filling content of 53.6 wt% of micron-SiO2@nano-Ag (32.4 wt% of Ag) and 1.0 wt% of the coupling agent APTES. The conductive mechanism of the paste was discussed according to the “percolation theory”. The conductive line patterns fabricated through silk-screen printing were applied to be linked with a LED into a circuit, suggesting that the paste would have a potential application in electronic devices.
危险品化学品经营许可证（带存储）