Objective To study the ent-kaurane diterpenoids from Rabdosia rubescens. Methods The compounds were isolated by chromatographies and their structures were identified by spectral analyses. Results Four compounds were i...Objective To study the ent-kaurane diterpenoids from Rabdosia rubescens. Methods The compounds were isolated by chromatographies and their structures were identified by spectral analyses. Results Four compounds were isolated, and they were identified as bisrubescensin E (1), 2α,3α,24-trihydroxyurs-12-en-28-oic acid (2), 2α,3α,24-trihydroxyurs-12,20-(30)-dien-28-oic acid (3), and 6,7-dihydroxycoumarin (4). Conclusion Compound 1 is a new asymmetric ent-kauranoid dimer. Compound 2 is isolated from the plant for the first time. Compounds 3 and 4 are isolated from the plants of Rabdosia (Bl.) Hassk for the first time.展开更多
Further investigation on the aerial parts of Isodon enanderianus afforded a novel asymmetric ent kauranoid dimer, enanderinanin J (1). The structure of the dimer was elucidated by means of spectroscopic m...Further investigation on the aerial parts of Isodon enanderianus afforded a novel asymmetric ent kauranoid dimer, enanderinanin J (1). The structure of the dimer was elucidated by means of spectroscopic methods (including 2D NMR techniques). Enanderinanin J was a dimer of xerophilusin A and probably formed by cycloaddition.展开更多
It is highly desirable to flexibly and actively manipulate the dephasing time of a plasmon in many potential applications;however,this remains a challenge.In this work,by using femtosecond time-resolved photoemission ...It is highly desirable to flexibly and actively manipulate the dephasing time of a plasmon in many potential applications;however,this remains a challenge.In this work,by using femtosecond time-resolved photoemission electron microscopy,we experimentally demonstrated that the Fano resonance mode in the asymmetric nanorod dimer can greatly extend the dephasing time of a femtosecond plasmon,whereas the non-Fano resonance results in a smaller dephasing time due to the large radiative damping,and flexible manipulation of the dephasing time can be realized by adjusting one of the nanorods in the Fano asymmetric dimer.Interestingly,it was found that plasmon resonance wavelengths both appeared red-shifted as the length of the upper or lower nanorods increased individually,but the dephasing time varied.Furthermore,it also indicated that the dephasing time can be prolonged with a smaller ascending rate by increasing the length of both the nanorods simultaneously while keeping the dimer asymmetry.Meanwhile,the roles of radiative and nonradiative damping in dephasing time are unveiled in the process of nanorod length variation.These results are well supported by numerical simulations and calculations.展开更多
文摘Objective To study the ent-kaurane diterpenoids from Rabdosia rubescens. Methods The compounds were isolated by chromatographies and their structures were identified by spectral analyses. Results Four compounds were isolated, and they were identified as bisrubescensin E (1), 2α,3α,24-trihydroxyurs-12-en-28-oic acid (2), 2α,3α,24-trihydroxyurs-12,20-(30)-dien-28-oic acid (3), and 6,7-dihydroxycoumarin (4). Conclusion Compound 1 is a new asymmetric ent-kauranoid dimer. Compound 2 is isolated from the plant for the first time. Compounds 3 and 4 are isolated from the plants of Rabdosia (Bl.) Hassk for the first time.
文摘Further investigation on the aerial parts of Isodon enanderianus afforded a novel asymmetric ent kauranoid dimer, enanderinanin J (1). The structure of the dimer was elucidated by means of spectroscopic methods (including 2D NMR techniques). Enanderinanin J was a dimer of xerophilusin A and probably formed by cycloaddition.
基金National Natural Science Foundation of China(12004052,61775021,62005022,91850109)111 Project(D17017)+1 种基金Jilin Provincial Key Laboratory of Ultrafast and Extreme Ultraviolet Optics(YDZJ202102CXJD028)Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing,Changchun University of Science and Technology.
文摘It is highly desirable to flexibly and actively manipulate the dephasing time of a plasmon in many potential applications;however,this remains a challenge.In this work,by using femtosecond time-resolved photoemission electron microscopy,we experimentally demonstrated that the Fano resonance mode in the asymmetric nanorod dimer can greatly extend the dephasing time of a femtosecond plasmon,whereas the non-Fano resonance results in a smaller dephasing time due to the large radiative damping,and flexible manipulation of the dephasing time can be realized by adjusting one of the nanorods in the Fano asymmetric dimer.Interestingly,it was found that plasmon resonance wavelengths both appeared red-shifted as the length of the upper or lower nanorods increased individually,but the dephasing time varied.Furthermore,it also indicated that the dephasing time can be prolonged with a smaller ascending rate by increasing the length of both the nanorods simultaneously while keeping the dimer asymmetry.Meanwhile,the roles of radiative and nonradiative damping in dephasing time are unveiled in the process of nanorod length variation.These results are well supported by numerical simulations and calculations.
