ABSTRACT Vanadium dioxide (VO2) is a typical representative of the strongly correlated electronic system. It presents a reversible first-order metal-insulator transition once stimulated by temperature, voltage, light, or pressure. The insulation-metal phase transition (MIT) makes it a new type of functional material with excellent potential applications in many fields. In this paper, magnetron sputtering technology and the "two-step method" process are used to prepare the VO2 films with phase transition properties. The results show that after the classic V film is processed for more than 100 minutes in air, and annealed in N2 atmosphere for 150 minutes, the VO2 (M) can be obtained with a resistance change rate more than three orders of magnitude. The study of the resistance change under the action of temperature and voltage found that the temperature of the heating and cooling phase transition are 67.4ºC and 62.8ºC respectively, and the hysteresis width is 4.6ºC. The relationship between phase transition voltage and ambient temperature is presented based on the heat dissipation model. It is found that Joule heating plays a significant role in the electro-induced phase transition of VO2. Furthermore, the ambient temperature has an obvious regulation effect on the phase transition voltage of VO2 film. The research results can provide efficient guidance to the preparation of VO2 film and the application and regulation of electro-induced phase transition.

Abstract In order to optimize the performance of chitosan-tea polyphenols composite films, effects of glycerol and Tween on the antioxidative activities and physical performance of chitosan composite films were evaluated. The results indicated that both flexibility and water vapour permeability of chitosan/tea polyphenols films were improved with the addition of glycerol, meanwhile the solubility and swelling degree decreased. Moreover, the release time of antioxidants from films was delayed with the addition of glycerol. The presence of Tween 20 had no significant effect on the tensile strength of films, but changed the DPPH radical scavenging activity depending on the blend ratio of glycerol and Tween. DSC, FTIR and X-ray analysis showed strong interaction among chitosan, tea polyphenols, glycerol and Tween. The optimum ratio was 0.5% tea polyphenols, 1.2% glycerol and 0.1% Tween. This study provided a reference that an optimized chitosan/tea polyphenols composite film could be obtained by the regulation of glycerol and Tween.

Abstract In this paper, the microstructure, water properties and browning control of Chinese water chestnut (CWC) after harvest were studied. Results showed that the tuber cell contained a large number of starch granules (5-10 μm for each one). The water-holding capacity of tuber cell was weak and T2 relaxation time was 28.5-75.6 ms. Sucrose was the main sugar component in Chinese water chestnut, which account for 84.8% of total sugar. In addition, potassium sorbate, green tea polyphenol and chitosan decreased the browning of fresh-cut CWC compared with the other anti-browning agents such as acetic acid, citric acid, oxalic acid, vitamin C and thyme oil. Moreover, chitosan coating combined with potassium sorbate and green tea polyphenol delayed weight loss and decay of fresh-cut tubers, also maintained a higher soluble solids and ascorbic acid content. The study provided an alternative method for controlling CWC browning, which would be helpful for the application of anti-browning agents in CWC processing.