Two new 2H-pyran-2-one glucosides,cuscutarosides A(1)and B(2),and one new steroidal glucoside,7β-methoxy-β-sitosterol 3-O-β-glucopyranoside(3),together with 12 known compounds(4-15)were isolated from the whole plan...Two new 2H-pyran-2-one glucosides,cuscutarosides A(1)and B(2),and one new steroidal glucoside,7β-methoxy-β-sitosterol 3-O-β-glucopyranoside(3),together with 12 known compounds(4-15)were isolated from the whole plant of Cuscuta reflexa(Convolvulaceae)collected from Myanmar.The chemical structures of these new compounds were elucidated based on extensive spectroscopic analysis.The antiobesity activity of these isolates was evaluated using porcine pancreatic lipase(PPL),and the antiplatelet aggregation activity was screened using rabbit platelets induced by thrombin,platelet-activating factor(PAF),arachidonate(AA),or collagen.7β-Methoxy-β-sitosterol 3-O-β-glucopyranoside(3)showed weak PPL inhibitory activity.Cuscutaroside A(1),its acetylated derivative(1a),and scrophenoside B(8)showed weak inhibitory activity against rabbit platelet aggregation induced by collagen.Compound 1a also showed inhibitory activity against rabbit platelet aggregation induced by AA.展开更多
We aimed at reporting the chemical constituents and antimicrobial activities of Leea aequata L.,a traditional folk medicine used in Myanmar for the treatment of wounds and skin diseases.A new neolignan,(7S,8R)-9′-O-a...We aimed at reporting the chemical constituents and antimicrobial activities of Leea aequata L.,a traditional folk medicine used in Myanmar for the treatment of wounds and skin diseases.A new neolignan,(7S,8R)-9′-O-acetylcedrusin(1),a new lactam,(3S,4S)-4-chloro-3-hydroxypiperidin-2-one(2),along with 21 known compounds,including fve lignans(3-7),four favonoid glycosides(8-11),and others(12-23),were isolated from the ethanoic extract of the aerial parts of L.aequata.The structures of the new compounds were determined by NMR,MS,and ECD spectra.For all the antimicrobial tests of the 23 compounds,only 3,4,5-trihydroxybenzoic acid ethyl ester(17)showed weak inhibitory activities against Escherichia coli and Salmonella enterica subsp.enterica.展开更多
The above-threshold ionization process of ammonia molecules induced by a femtosecond laser field at 800 nm is studied in the intensity range from 1.6×10^(13) to 5.7×10^(13)W/cm^(2).Channel switching under di...The above-threshold ionization process of ammonia molecules induced by a femtosecond laser field at 800 nm is studied in the intensity range from 1.6×10^(13) to 5.7×10^(13)W/cm^(2).Channel switching under different laser intensities is observed and identified in the photoelectron kinetic energy spectra of ammonia.Based on the photoelectron kinetic energy distributions and the photoelectron angular distributions,the characteristic peaks observed are exclusively assigned to the multiphoton resonance through certain intermediate states,followed by multiphoton above-threshold ionization.展开更多
MXene,an emerging two-dimensional(2D)layered material,has received worldwide attention in various energy storage systems because of its excellent properties.Nevertheless,the low capacity of pristine MXene restricts it...MXene,an emerging two-dimensional(2D)layered material,has received worldwide attention in various energy storage systems because of its excellent properties.Nevertheless,the low capacity of pristine MXene restricts its application in energy storage devices especially for the lithium-ion batteries(LIBs).To address the above issue,herein,a stable and highly conductive double transition metal MXene(Ti_(2)NbC_(2)T_(x)) is successfully fabricated,which provides enlarged interlayer spacing and excellent conductivity for fast ion diffusion and charge transfer.Taking the Ti_(2)NbC_(2)T_(x)s anode for LIBs,a superior specific capacity of 196.2 mAh·g-1and an excellent long-term cycling stability of~100%after 400cycles under 0.1 A·g^(-1) are achieved for LIBs.In particular,Ti_(2)NbC_(2)T_(x) delivers an impressive capacity retention of 81%over 4000 cycle under 1 A·g^(-1),outperforming the Ti_(3)C_(2)T_(x) and various previously reported MXene-based materials.Our results offer an attractive strategy for the future application of MXene-based materials.展开更多
A family of tropos ligands bearing a N-heterocyclic carbene and a chiral oxazoline coordination group with a N-phenyl framework were easily prepared,and their coordination behavior with Pd（Ⅱ）acetate was performed,a...A family of tropos ligands bearing a N-heterocyclic carbene and a chiral oxazoline coordination group with a N-phenyl framework were easily prepared,and their coordination behavior with Pd（Ⅱ）acetate was performed,affording a series of axially chiral palladium complexes in good yields.展开更多
A series of novel bridged-neonicotinoid analogues were designed and synthesized, which were constructed by starting material 8 with cyclopentenone or cyclohexenone in the presence of catalyst aluminium chloride. All o...A series of novel bridged-neonicotinoid analogues were designed and synthesized, which were constructed by starting material 8 with cyclopentenone or cyclohexenone in the presence of catalyst aluminium chloride. All of the compounds were characterized and confirmed by^1H NMR,^（13）C NMR, HRMS and IR. The bioassay tests showed that compounds 5 and 6a showed higher bioactivities than imidacloprid against Aphis craccivora.展开更多
基金supported by the Southeast Asia Biodiversity Research Institute,Chinese Academy of Sciences(Grant Nos.2015CASEABRIRG001 and Y4ZK111B01)the International Partnership Program of Chinese Academy of Sciences(Grant No.153631KYSB20160004)+2 种基金the National Natural Science Foundation of China(31960480)the Joint Special Project of Local Undergraduate Universities in Yunnan Province,China(Grant No.2018FH001-024)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program of Ministry of Science and Technology of the People’s Republic of China(Grant No.2019QZKK0502).
文摘Two new 2H-pyran-2-one glucosides,cuscutarosides A(1)and B(2),and one new steroidal glucoside,7β-methoxy-β-sitosterol 3-O-β-glucopyranoside(3),together with 12 known compounds(4-15)were isolated from the whole plant of Cuscuta reflexa(Convolvulaceae)collected from Myanmar.The chemical structures of these new compounds were elucidated based on extensive spectroscopic analysis.The antiobesity activity of these isolates was evaluated using porcine pancreatic lipase(PPL),and the antiplatelet aggregation activity was screened using rabbit platelets induced by thrombin,platelet-activating factor(PAF),arachidonate(AA),or collagen.7β-Methoxy-β-sitosterol 3-O-β-glucopyranoside(3)showed weak PPL inhibitory activity.Cuscutaroside A(1),its acetylated derivative(1a),and scrophenoside B(8)showed weak inhibitory activity against rabbit platelet aggregation induced by collagen.Compound 1a also showed inhibitory activity against rabbit platelet aggregation induced by AA.
基金supported by the Southeast Asia Biodiversity Research Institute,Chinese Academy of Sciences(Grant Nos.2015CASEABRIRG001 and Y4ZK111B01)the International Partnership Program of Chinese Academy of Sciences(153631KYSB20160004).
文摘We aimed at reporting the chemical constituents and antimicrobial activities of Leea aequata L.,a traditional folk medicine used in Myanmar for the treatment of wounds and skin diseases.A new neolignan,(7S,8R)-9′-O-acetylcedrusin(1),a new lactam,(3S,4S)-4-chloro-3-hydroxypiperidin-2-one(2),along with 21 known compounds,including fve lignans(3-7),four favonoid glycosides(8-11),and others(12-23),were isolated from the ethanoic extract of the aerial parts of L.aequata.The structures of the new compounds were determined by NMR,MS,and ECD spectra.For all the antimicrobial tests of the 23 compounds,only 3,4,5-trihydroxybenzoic acid ethyl ester(17)showed weak inhibitory activities against Escherichia coli and Salmonella enterica subsp.enterica.
基金supported by the National Natural Science Foundation of China(Grant Nos.11574116,11534004,11704147,and 10704028)。
文摘The above-threshold ionization process of ammonia molecules induced by a femtosecond laser field at 800 nm is studied in the intensity range from 1.6×10^(13) to 5.7×10^(13)W/cm^(2).Channel switching under different laser intensities is observed and identified in the photoelectron kinetic energy spectra of ammonia.Based on the photoelectron kinetic energy distributions and the photoelectron angular distributions,the characteristic peaks observed are exclusively assigned to the multiphoton resonance through certain intermediate states,followed by multiphoton above-threshold ionization.
基金supported by the National Science,Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(No.B05F640153)the National Research Council of Thailand(NRCT)(No.NRCT5-RSA63001-19)+2 种基金the National Natural Science Foundation of China(No.52125405)the National Key R&D Program of China(No.2018YFA0703602)financially supporting from the Second Century Fund(C2F),Chulalongkorn University。
文摘MXene,an emerging two-dimensional(2D)layered material,has received worldwide attention in various energy storage systems because of its excellent properties.Nevertheless,the low capacity of pristine MXene restricts its application in energy storage devices especially for the lithium-ion batteries(LIBs).To address the above issue,herein,a stable and highly conductive double transition metal MXene(Ti_(2)NbC_(2)T_(x)) is successfully fabricated,which provides enlarged interlayer spacing and excellent conductivity for fast ion diffusion and charge transfer.Taking the Ti_(2)NbC_(2)T_(x)s anode for LIBs,a superior specific capacity of 196.2 mAh·g-1and an excellent long-term cycling stability of~100%after 400cycles under 0.1 A·g^(-1) are achieved for LIBs.In particular,Ti_(2)NbC_(2)T_(x) delivers an impressive capacity retention of 81%over 4000 cycle under 1 A·g^(-1),outperforming the Ti_(3)C_(2)T_(x) and various previously reported MXene-based materials.Our results offer an attractive strategy for the future application of MXene-based materials.
基金the National Natural Science Foundation of China for financial support (Nos. 21372075 and 61376003)
文摘A family of tropos ligands bearing a N-heterocyclic carbene and a chiral oxazoline coordination group with a N-phenyl framework were easily prepared,and their coordination behavior with Pd（Ⅱ）acetate was performed,affording a series of axially chiral palladium complexes in good yields.
基金financial supported by Shandong Provincial Natural Science Foundation (No. ZR2015BL009)The Key Research and Development Program of Shandong Provincial (No. 2016GGX107006)+1 种基金National Natural Science Foundation of China (No. 21501066)the Opening Project of Shanghai Key Laboratory of Chemical Biology
文摘A series of novel bridged-neonicotinoid analogues were designed and synthesized, which were constructed by starting material 8 with cyclopentenone or cyclohexenone in the presence of catalyst aluminium chloride. All of the compounds were characterized and confirmed by^1H NMR,^（13）C NMR, HRMS and IR. The bioassay tests showed that compounds 5 and 6a showed higher bioactivities than imidacloprid against Aphis craccivora.
