New Technology for the Synthesis of Glycerol Monooleate.

Herein, a new approach for glycerol monooleate (GMO) was developed. GMO was synthesized via the esterification method using self-made sodium oleate and 3-chloro-1,2-propanediol as reactants, tetrabutylammonium bromide as the catalyst, and toluene as the solvent. The effects of the reaction molar ratio, type and amount of catalyst, and reaction temperature and time on the yield were investigated. Results showed that the optimal process conditions for synthesizing GMO were as follows. The molar ratio of sodium oleate to 3-chloro-1,2-propanediol was 1:2, the reaction temperature was 115°C, the reaction time was 6 h, weight of toluene was 25 g, and the catalyst dosage was 3.5%. Under these conditions, high-purity GMO was synthesized with a yield of 89.02%.

Sustainable and Transparent Fish Gelatin Films for Flexible Electroluminescent Devices.

In the past decades, various alternating current electroluminescent (ACEL) devices, especially the flexible ones, have been developed and used in flat panel display, large-scale decorating, logo display lighting, optical signaling, etc. Transparent plastics are usually used as substrates in ACEL devices; however, they are undegradable and may cause serious environmental pollution. Herein, we have developed a flexible transient ACEL device based on transparent fish gelatin (FG) films. The FG films were made from fish scales, which are sustainable, cost-efficient, and eco-friendly. These films could dissolve in water within seconds at 60 °C and degrade completely within 24 days in soil. The transmittance of these FG films was up to 91.1% in the visible spectrum, comparable to that of polyethylene terephthalate (PET) (90.4%). After forming a composite with silver nanowires (Ag NWs), the Ag NWs-FG film showed a transmittance up to 82.3% and a sheet resistance down to 22.4 Ω sq-1. The fabricated ACEL device based on the Ag NWs-FG film exhibited high flexibility and luminance up to 56.0 cd m-2. The device could be dissolved in water within 3 min. Our work demonstrates that the sustainable, flexible, and transparent FG films are a promising alternative for green and degradable substrates in the field of flexible electronics, including foldable displays, wearable devices, and health monitoring.

Fish Gelatin Based Triboelectric Nanogenerator for Harvesting Biomechanical Energy and Self-Powered Sensing of Human Physiological Signals.

Triboelectric nanogenerator (TENG) has been proven effective in converting biomechanical energy into electrical energy, which is expected to be a new energy supply device for wearable electronics and can be utilized as a self-powered sensor. In this work, we have developed a flexible, eco-friendly, and multifunctional fish gelatin based triboelectric nanogenerator (FG-TENG) composed of fish gelatin (FG) film and poly(tetrafluoroethylene)/poly(dimethylsiloxane) (PTFE/PDMS) composite film. The open-circuit voltage (Voc), short-circuit current (Isc), and output power density of this FG-TENG could reach up to 130 V, 0.35 µA, and 45.8 µW cm-2, respectively, which were significantly higher than those of TENGs based on other commonly used positive friction materials such as aluminum foil, poly(ethylene terephthalate) (PET), and print paper. The superior performance of the FG-TENG is attributed to the strong electron-donating ability of the FG during the triboelectric process. The generated electric energy was high enough to light up 50 commercial light-emitting diodes (LEDs) directly. Importantly, owing to the high stability and excellent sensitivity of the FG-TENG, it has been used as a self-powered sensor for real-time monitoring of the human physiological signals such as finger touch, joint movement, and respiration. Furthermore, to expand the usages in real-life applications, a foldable FG-TENG was fabricated by adopting the Miura folding to monitor human movements in real time. This work provides an economical, simple, and environmental-friendly approach to fabricate a biomechanical energy harvester, which has a great potential in powering next-generation wearable electronics and monitoring human physiological signals.

Using magnetic levitation for density-based detection of cooking oils.

Adulterated cooking oils and the repeated use of frying cooking oils are harmful to human health. Current techniques for the quality control of cooking oils such as gas chromatography and high performance liquid chromatography usually require expensive facilities, and they are complicated to operate. This paper describes a simple technique that uses magnetic levitation (MagLev) to analyse cooking oils based on density. We have demonstrated the application of MagLev to detect the quality of cooking oil by simulating adulterated sesame oil using peanut oil and frying soybean oil for different times. We have also demonstrated the use of MagLev to differentiate secondhand cooking oil from certified cooking oil. MagLev provides a portable and inexpensive method for the on-site inspection of cooking oils, and it may be extended to many other applications in food safety, environmental monitoring, medical diagnosis, and so on. The advantages of high sensitivity, low cost, and convenience of operation make MagLev especially useful for in situ applications in resource-limited settings.