An edible and pH-sensitive film combined with electrochemical writing was developed using gelatin, gellan gum and red radish anthocyanin extract for intelligent food packaging applications. The composite film displays orange red-to-yellow color change over the pH range 2-12. The tensile strength, ductility, and barrier response of the films to UV light and oxygen improved with the increase of red radish anthocyanin concentration. Multicolor patterns were successfully drawn on the film using an electrochemical writing method. The composite films acted as gas sensors which presented visible color changes in the presence of milk and fish spoilage, while the written patterns were well preserved. Accordingly, this composite film with written patterns could be an easy-to-use indicator with great potential for monitoring food spoilage as part of an intelligent packaging system.
In this paper, we describe a systemic approach for the preparation of different-phase titanium dioxide nanocomposites with peroxotitanium complex (PTC) as a precursor in aqueous solution by a low-temperature process. Three phases (anatase, rutile, and brookite) of TiO 2 nanoparticles were prepared by refluxing the PTC precursor at different pH values at 100 °C and ambient pressure. At pH ) 0, acicular rutile-phase nanoparticles were prepared, while at a pH of about 1, a stable milk white sol that contains about 63% brookite phase was obtained; the brookite particles are mainly irregular quadrate. Furthermore, the spherical and spindle anatase nanoparticles were prepared from the precursor with pH ) 3 and 6, respectively. The influence of the different concentration of the peroxide on the products was also investigated. It is noticed that there was an optimum H 2 O 2 /Ti molar ratio for different phase formation. Finally, the photocatalytic properties of different products were measured by decomposing methylene blue. The spherical anatase phase showed higher photocatalytic degradation rates for methylene blue than others.
The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.
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