A detailed chemical investigation of the red resins from Dracaena cochinchinensis(Chinese dragon’s blood)yielded five new flavonoid oligomers,named cochinchinenins D-H(1-5),together with a known biflavonoid,cinnabaro...A detailed chemical investigation of the red resins from Dracaena cochinchinensis(Chinese dragon’s blood)yielded five new flavonoid oligomers,named cochinchinenins D-H(1-5),together with a known biflavonoid,cinnabarone(6),and a mixture of two known biflavonoids,socotrin-4'-ol(7)and homoisosocotrin-4'-ol(8).Of these new compounds,1-3 were biflavonoids and 4 and 5 were triflavonoids.Their structures were determined on the basis of spectroscopic analysis.The isolated compounds were tested for cytotoxicity(Cdc25),antibacterial(PEPT)and antifungal(YNG)activities.展开更多
The 40Cr steel matrix composites were reinforced with Al203 particulates （Al2O3p） through Si adding to improve the impact-abrasive wear resistance, in which Si powder ranging up to 25% of the AlzO3p weight was added...The 40Cr steel matrix composites were reinforced with Al203 particulates （Al2O3p） through Si adding to improve the impact-abrasive wear resistance, in which Si powder ranging up to 25% of the AlzO3p weight was added into the Al2O3p preforms; then, the composites were fabricated by squeeze casting. For all composites, alumina particles are evenly distributed, and Si powder is dissolved in the matrix. Without Si powder addition, the 40Cr steel matrix contains only pearlite; however, ferrite appears and increases with Si powder addition. In the impact-abrasive wear tests, the impact frequency is 80 min^-1 and the impacting energy is 2 J. With increasing Si powder, the wear of the composites first decreases obviously, reaches the minimum at 10% and then increases. The effect of Si addition on the wear resistance can be attributed to two reasons： one is increasing the hardness of the matrix, and the other is improving the interfacial bonding between Al2O3p and steel. The wear mechanism of the composites is abrasive wear when the Si powder is 〈 10 wt%. Otherwise, it is a mixed mode of abrasive and delamination wear.展开更多
基金supported by the 973 Program of Ministry of Science and Technology of China(2011CB915503)the Fourteenth Candidates of the Young Academic Leaders of Yunnan Province(Min XU,2011CI044),and NSFC 31060054.
文摘A detailed chemical investigation of the red resins from Dracaena cochinchinensis(Chinese dragon’s blood)yielded five new flavonoid oligomers,named cochinchinenins D-H(1-5),together with a known biflavonoid,cinnabarone(6),and a mixture of two known biflavonoids,socotrin-4'-ol(7)and homoisosocotrin-4'-ol(8).Of these new compounds,1-3 were biflavonoids and 4 and 5 were triflavonoids.Their structures were determined on the basis of spectroscopic analysis.The isolated compounds were tested for cytotoxicity(Cdc25),antibacterial(PEPT)and antifungal(YNG)activities.
基金Project(51475326)supported by the National Natural Science Foundation of ChinaProject(BHSF2017-22)supported by the Demonstration Program of National Marine Economic Innovation of Tianjin City,China。
基金This work was supported by the financial support of National Natural Science Foundation of China （Grant No. 51265019）.
文摘The 40Cr steel matrix composites were reinforced with Al203 particulates （Al2O3p） through Si adding to improve the impact-abrasive wear resistance, in which Si powder ranging up to 25% of the AlzO3p weight was added into the Al2O3p preforms; then, the composites were fabricated by squeeze casting. For all composites, alumina particles are evenly distributed, and Si powder is dissolved in the matrix. Without Si powder addition, the 40Cr steel matrix contains only pearlite; however, ferrite appears and increases with Si powder addition. In the impact-abrasive wear tests, the impact frequency is 80 min^-1 and the impacting energy is 2 J. With increasing Si powder, the wear of the composites first decreases obviously, reaches the minimum at 10% and then increases. The effect of Si addition on the wear resistance can be attributed to two reasons： one is increasing the hardness of the matrix, and the other is improving the interfacial bonding between Al2O3p and steel. The wear mechanism of the composites is abrasive wear when the Si powder is 〈 10 wt%. Otherwise, it is a mixed mode of abrasive and delamination wear.
