Carbohydrates are involved in a wide range of biological processes. These structurally diverse compounds are more complex than other biological polymers, and are often present as heterogeneous mixtures in nature. The chemical synthesis of carbohydrates is one way to obtain pure oligosaccharides, but it is hampered by difficulties associated with the regioselective protection of polyhydroxyls and challenges related to the stereoselective assembly of glycosidic linkages. Here we describe a combinatorial, and highly-regioselective, method that can be used to protect individual hydroxy groups of a monosaccharide. This approach can be used to install an orthogonal protecting group pattern in a single reaction vessel (a 'one-pot' reaction), which removes the need to carry out the time-consuming isolation and purification of intermediates. Hundreds of building blocks have been efficiently prepared starting from d-glucose, and the iterative coupling of these building blocks enabled us to assemble beta-1,6-glucans and a library of oligosaccharides based on the influenza-virus-binding trisaccharide.
In this study, the effectiveness of using a perovskite/Zr‐metal–organic frameworks (MOFs) heterojunction in realizing efficient and stable inverted p–i–n perovskite solar cells (PVSCs) is demonstrated. Two types of Zr‐MOFs, UiO‐66 and MOF‐808, are investigated owing to their respectable moisture and chemical stabilities. The MOFs while serving as an interlayer in conjunction with the perovskite film are shown to possess the advantages of UV‐filtering capability and enhancing perovskite crystallinity. Consequently, the UiO‐66/MOF‐808‐modified PVSCs yield enhanced power conversion efficiencies (PCEs) of 17.01% and 16.55%, outperforming the control device (15.79%). While further utilizing a perovskite/Zr‐MOF hybrid heterojunction to fabricate the devices, the hybrid MOFs are found to possibly distribute over the perovskite grain boundary providing a grain‐locking effect to simultaneously passivate the defects and to reinforce the film's robustness against moisture invasion. As a result, the PCEs of the UiO‐66/MOF‐808‐hybrid PVSCs are further enhanced to 18.01% and 17.81%, respectively. Besides, over 70% of the initial PCE is retained after being stored in air (25 °C and relative humidity of 60 ± 5%) for over 2 weeks, in contrast to the quick degradation observed for the control device. This study demonstrates the promising potential of using perovskite/MOF heterojunctions to fabricate efficient and stable PVSCs.
Tartary buckwheat (Fagopyrum tataricum) is a healthy and nutritionally important food item. In this study, we investigated the hepatoprotective effects of 75% ethanol extracts from tartary buckwheat (EEB) against ethanol- and carbon tetrachloride (CCl(4))-induced liver damage. EEB were administered to C57BL/6 mice (ethanol induction) and Sprague-Dawley (SD) rats (CCl(4) induction) for 4 and 8 consecutive weeks, respectively. The major active compounds, rutin and quercetin, were also administered to ethanol- and CCl(4)-induced animals. EEB inhibited increase in serum aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) levels in the ethanol- and CCl(4)-induced animals; similar effects were found after rutin and quercetin administration. Moreover, EEB elevated the antioxidant enzyme activities, including those of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD), and inhibited the levels of hepatic inflammation in the ethanol- and CCl(4)-treated animals. This study suggests that EEB exerts hepatoprotection via promoting anti-oxidative and anti-inflammatory properties against oxidative liver damage.
Two conjugated covalent organic frameworks (COFs) are successfully synthesized and are introduced as the interface modifier in perovskite solar cells (PVSCs) to enhance the overall performance.
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