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Background: As an important global agricultural cash crop, melon has a long history of cultivation and a wide planting area. The physiological metabolism of melon after harvest is relatively strong; if not properly stored, melon is easily invaded by external pathogens during transportation, resulting in economic losses and greatly limiting its production, development and market supply. Therefore, the storage and freshness of melon are the main challenges in realizing the annual supply of melon, so postharvest storage has received increasing amounts of attention from researchers. Methods: This study used academic, PubMed, and Web of Science resources to retrieve keywords related to postharvest storage and melon quality; read, refined, classified, and sorted the retrieved literature; sorted and summarized the relevant research results; and finally completed this article. Results: This article reviews the mechanism and effects of physical, chemical and biological preservation techniques on the sensory quality, compound contents and respiratory physiological activities of different varieties of melon fruits. When maintaining normal metabolism and not producing physiological disorders, melon inhibits cell wall metabolism, reactive oxygen species metabolism and the ethylene biosynthesis pathway, etc., to the greatest extent during postharvest storage, thereby reducing the material consumption of fruits, delaying the ripening and senescence process, and prolonging the postharvest life and shelf life. Conclusion: The literature provides a theoretical basis for postharvest preservation technology in the melon industry in the future and provides corresponding guidance for the development of the melon industry. [ABSTRACT FROM AUTHOR]

Cu-ZnO-based catalysts are widely used to catalyze the CO2 hydrogenation to methanol and reverse water-gas shift (RWGS) reactions. Herein, via a combined experimental and theoretical calculation study of various Cu nanocrystals (NCs) with well-defined Cu facets and corresponding ZnO/Cu NC inverse catalysts, we demonstrate the Cu{110} facets as the most active facet for ZnO-Cu interfacial catalysis in the CO2 hydrogenation to methanol with an apparent activation energy as low as 25.3±3 kJ mol−1 and the Cu{100} facets as the most active facet for both ZnO-Cu interfacial catalysis and Cu catalysis in the RWGS reaction. Although the ZnO-Cu interface is more active in catalyzing the RWGS reaction than the Cu surface, the RWGS reaction occurs mainly on the bare Cu surface of ZnO/Cu inverse catalysts under the CO2 hydrogenation to methanol instead of that at the ZnO-Cu interface. This fundamental understanding will greatly help to fabricate efficient Cu-ZnO-based catalysts for the CO2 hydrogenation to methanol. [ABSTRACT FROM AUTHOR]

H2O2 is widely used as an oxidant for photocatalytic methane conversion to value-added chemicals over oxide-based photocatalysts under mild conditions, but suffers from low utilization efficiencies. Herein, we report that O2 is an efficient molecular additive to enhance the utilization efficiency of H2O2 by suppressing H2O2 adsorption on oxides and consequent photogenerated holes-mediated H2O2 dissociation into O2. In photocatalytic methane conversion over an anatase TiO2 nanocrystals predominantly enclosed by the {001} facets (denoted as TiO2{001})-C3N4 composite photocatalyst at room temperature and ambient pressure, O2 additive significantly enhances the utilization efficiency of H2O2 up to 93.3%, giving formic acid and liquid-phase oxygenates selectivities respectively of 69.8% and 97% and a formic acid yield of 486 μmolHCOOH·gcatalyst−1·h−1. Efficient charge separation within TiO2{001}-C3N4 heterojunctions, photogenerated holes-mediated activation of CH4 into ·CH3 radicals on TiO2{001} and photogenerated electrons-mediated activation of H2O2 into ·OOH radicals on C3N4, and preferential dissociative adsorption of methanol on TiO2{001} are responsible for the active and selective photocatalytic conversion of methane to formic acid over TiO2{001}-C3N4 composite photocatalyst. The oxidation of methane to formic acid or related oxygenates relies on efficient reaction with H2O2. Here, the authors report a TiO2-based catalyst to selectively form formic acid by using molecular O2 additives to avoid unwanted side reactions. [ABSTRACT FROM AUTHOR]

The identification of the contribution of different surface sites to the catalytic activity of a catalyst nanoparticle is one of the most challenging issues in the fundamental studies of heterogeneous catalysis. We herein demonstrate an effective strategy of using a series of uniform cubic Cu2O nanocrystals with different sizes to identify the intrinsic activity and contributions of face and edge sites in the catalysis of CO oxidation by a combination of reaction kinetics analysis and DFT calculations. Cu2O nanocrystals undergo in situ surface oxidation forming CuO thin films during CO oxidation. As the average size of the cubic Cu2O nanocrystals decreases from 1029 nm to 34 nm, the dominant active sites contributing to the catalytic activity switch from face sites to edge sites. These results reveal the interplay between the intrinsic catalytic activity and the density of individual types of surface sites on a catalyst nanoparticle in determining their contributions to the catalytic activity. Choose your site: The dominant active site of CuO thin films on cubic Cu2O nanocrystals contributing to the catalytic oxidation of CO switches from face sites for large nanocrystals to edge sites for small ones. This reveals the interplay between the intrinsic catalytic activity and the density of individual types of surface sites on a catalyst nanoparticle. [ABSTRACT FROM AUTHOR]

Background: Hyperlipidemia is a worldwide health problem and a significant risk factor for cardiovascular diseases; therefore, it imposes a heavy burden on society and healthcare. It has been reported that flavonoids can increase energy expenditure and fat oxidation, be anti-inflammatory, and reduce lipid factor levels, which may reduce the risk of hyperlipidemia. However, the relationship between the prevalence of hyperlipidemia and dietary flavonoid intake in the population remains unclear., Methods: This study included 8,940 adults from the 2007-2010 and 2017-2018 National Health and Nutrition Examination Surveys (NHANES). The relationship between dietary flavonoid intake and the prevalence of hyperlipidemia was analyzed using weighted logistic regression and weighted restricted cubic spline., Results: We found an inverse relationship between subtotal catechins intake and hyperlipidemia prevalence in the third quartile [0.74 (0.56, 0.98), p = 0.04] compared with the first quartile. The prevalence of hyperlipidemia and total flavan-3-ol intake in the third quartile were inversely correlated [0.76 (0.59, 0.98), p = 0.03]. Total anthocyanin intake was inversely related to the prevalence of hyperlipidemia in the third quartile [0.77 (0.62, 0.95), p = 0.02] and the fourth quartile [0.77 (0.60, 0.98), p = 0.04]. The prevalence of hyperlipidemia was negatively correlated with total flavonols intake in the fourth quartile [0.75 (0.60, 0.94), p = 0.02]. Using restricted cubic splines analysis, we found that subtotal catechins intake and total flavan-3-ol intake had a nonlinear relationship with the prevalence of hyperlipidemia., Conclusion: Our study may provide preliminary research evidence for personalizing improved dietary habits to reduce the prevalence of hyperlipidemia., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wan, Ma, Yu, Tian, Wang, Chen, Shang and Xu.)

The identification of the contribution of different surface sites to the catalytic activity of a catalyst nanoparticle is one of the most challenging issues in the fundamental studies of heterogeneous catalysis. We herein demonstrate an effective strategy of using a series of uniform cubic Cu 2 O nanocrystals with different sizes to identify the intrinsic activity and contributions of face and edge sites in the catalysis of CO oxidation by a combination of reaction kinetics analysis and DFT calculations. Cu 2 O nanocrystals undergo in situ surface oxidation forming CuO thin films during CO oxidation. As the average size of the cubic Cu 2 O nanocrystals decreases from 1029 nm to 34 nm, the dominant active sites contributing to the catalytic activity switch from face sites to edge sites. These results reveal the interplay between the intrinsic catalytic activity and the density of individual types of surface sites on a catalyst nanoparticle in determining their contributions to the catalytic activity., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

P-type Cu2 O has been long considered as an attractive photocatalyst for photocatalytic water reduction, but few successful examples has been reported. Here, we report the synthesis of TiO2 (core)/Cu2 O (ultrathin film shell) nanorods by a redox reaction between Cu(2+) and in-situ generated Ti(3+) when Cu(2+) -exchanged H-titanate nanotubes are calcined in air. Owing to the strong TiO2 -Cu2 O interfacial interaction, TiO2 (core)/Cu2 O (ultrathin film shell) nanorods are highly active and stable in photocatalytic water reduction. The TiO2 core and Cu2 O ultrathin film shell respectively act as the photosensitizer and cocatalyst, and both the photoexcited electrons in the conduction band and the holes in the valence band of TiO2 respectively transfer to the conduction band and valence band of the Cu2 O ultrathin film shell. Our results unambiguously show that Cu2 O itself can act as the highly active and stable cocatalyst for photocatalytic water reduction., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)