This review paper is focused on the relative antioxidant activities of tocopherols and tocotrienols in oils and fats and certain food systems. a-Tocopherol generally showed better antioxidant activity than c-tocopherol in fats and oils, but at higher concentrations c-tocopherol was found to be a more active antioxidant. The results of studies on the optimum antioxidant concentrations of tocopherols in oils and fats indicated that the optimal level for a-tocopherol is usually lower than other tocopherols, meaning less a-tocopherol is needed for maximum antioxidant protection. There are comparatively very few studies related to the antioxidant activities of tocotrienols in oils and fats. It has been stated that generally c-tocotrienol has higher antioxidant effect than a-tocotrienol, and tocotrienols may be better antioxidants than their corresponding tocopherols in certain oils and fats systems. Studies on the antioxidant activity of various tocopherols in food systems are varied and cannot be uniformly evaluated because experiments have generally focused on different foods and used various methods for the detection of antioxidant activities. Depending on the food system, in certain cases tocopherols were better antioxidants than synthetic antioxidants such as butylhydroxy toluene (BHT) or butylhydroxy anisole (BHA). However, in certain other food systems the synthetic antioxidants were more effective to increase the shelf life and the stability of foods than those containing tocopherols.

Solar-driven interfacial evaporation with heat localization is an efficient method for large-scale water purification. However, due to the high latent heat of water evaporation and dilute solar flux (1 kW m–2), the solar steam productivity is low. Here, the latent heat of water evaporation was reduced because of the capillary water state in wood channels. We constructed a wood-based 3D solar evaporator via regulating the hydrophilicity of a surface of burnt wood and adjusting the height of the wood above a water surface. Capillary water was formed in the light absorption layer, resulting in the latent heat decrease from 2444 to 1769 J g–1. A high evaporation rate of 1.93 kg m–2 h–1 under one sun irradiation (1 kW m–2) was achieved. Together with the environmental energy-harvesting ability, the evaporation rate reached 3.91 kg m–2 h–1 (per occupied area), which is among the best values ever reported. More importantly, the 3D solar evaporator works efficiently in a water collection device, yielding 2.2 times more water than that of a common interfacial evaporator.

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