The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chr...The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chromatography using Avicel as the adsorbent. After that, 50% of methanol in water was used as the eluting solvent and continued to further purify by Avicel preparative layer chromatogram 2 times using 80% of methanol in water as developing solvent. MIC of pure compound was done by two fold dilution method. Muller Hinton agar was selected as the media. The new compound was found as combretin, a steroidal alkaloid, and showed antibacterial activity against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 better than Staphylococcus aureus ATCC 25923.展开更多
Noble metals are downsized to nano-/subnanoscale to improve their catalytic activity and atom-economy.However,the stabilities in chemical state and catalytic performance of these nanocatalysts often suffer during hars...Noble metals are downsized to nano-/subnanoscale to improve their catalytic activity and atom-economy.However,the stabilities in chemical state and catalytic performance of these nanocatalysts often suffer during harsh conditions.For Pt nanoparticles(NPs)supported on CeO2,activated oxygen diffused from the support over-stabilizes the active sites of Pt,degrading its performance at mild temperature.In this work,Pt nanocatalysts with unique structure of triple-junction are synthesized by selectively growing Pt NPs on the carbon-CeO2 interface.Impressively,the Pt NPs exhibit much enhanced catalytic stability and high activity for CO oxidation at mild temperature.The enhancement is attributed to electron donation from graphitized carbon and the confinement effect from the high-density nanopores of the CeO2 support.The triple-junction of Pt-C-CeO2,combining the merits of CeO2 for activating O2 and electron donating capability of carbon,provides new inspiration to the fabrication of high-performance nanocatalysts.展开更多
基金National Natural Science Foundation of China(20777046,21077064)Specialized Research Fund for the Doctoral Program of Higher Education of China(20070003027)
文摘The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chromatography using Avicel as the adsorbent. After that, 50% of methanol in water was used as the eluting solvent and continued to further purify by Avicel preparative layer chromatogram 2 times using 80% of methanol in water as developing solvent. MIC of pure compound was done by two fold dilution method. Muller Hinton agar was selected as the media. The new compound was found as combretin, a steroidal alkaloid, and showed antibacterial activity against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 better than Staphylococcus aureus ATCC 25923.
基金supported by the National Key Research and Development Program of China(2016YFB0701100)the National Natural Science Foundation of China(51771047,51525101 and 51971059)the Fundamental Research Funds for the Central Universities(N180204014)。
文摘Noble metals are downsized to nano-/subnanoscale to improve their catalytic activity and atom-economy.However,the stabilities in chemical state and catalytic performance of these nanocatalysts often suffer during harsh conditions.For Pt nanoparticles(NPs)supported on CeO2,activated oxygen diffused from the support over-stabilizes the active sites of Pt,degrading its performance at mild temperature.In this work,Pt nanocatalysts with unique structure of triple-junction are synthesized by selectively growing Pt NPs on the carbon-CeO2 interface.Impressively,the Pt NPs exhibit much enhanced catalytic stability and high activity for CO oxidation at mild temperature.The enhancement is attributed to electron donation from graphitized carbon and the confinement effect from the high-density nanopores of the CeO2 support.The triple-junction of Pt-C-CeO2,combining the merits of CeO2 for activating O2 and electron donating capability of carbon,provides new inspiration to the fabrication of high-performance nanocatalysts.
