The stem and branch extract of Tripterygium wilfordii(Celastraceae)afforded seven new dihydroagarofuran sesquiterpene polyesters[tripterysines A‒G(1‒7)]and eight known ones(8‒15).The chemical structures of these new c...The stem and branch extract of Tripterygium wilfordii(Celastraceae)afforded seven new dihydroagarofuran sesquiterpene polyesters[tripterysines A‒G(1‒7)]and eight known ones(8‒15).The chemical structures of these new compounds were established based on combinational analysis of HR-ESI-MS and NMR techniques.The absolute configurations of tripterysines A‒C(1‒3)and E‒G(5‒7)were determined by X-ray crystallographic analysis and circular dichroism spectra.All the compounds were screened for their inhibitory effect on inflammation through determining their inhibitory effect on nitric oxide production in LPS-induced RAW 264.7 cells and the secretion of inflammatory cytokines TNF-αand IL-6 in LPS-induced BV2 macrophages.Compound 9 exhibited significant inhibitory activity on NO production with an IC50 value of 8.77μmol·L−1.Moreover,compound 7 showed the strongest inhibitory effect with the secretion of IL-6 at 27.36%.展开更多
The large eddy simulation(LES) method is used to simulate cavitating flow in a venturi tube. The simulated results agree fairly well with the experimental data. To quantitatively describe the relationship between cavi...The large eddy simulation(LES) method is used to simulate cavitating flow in a venturi tube. The simulated results agree fairly well with the experimental data. To quantitatively describe the relationship between cavitation evolution and excited pressure fluctuation in the venturi tube, a modified prediction model is proposed and its accuracy is verified by the LES results. Based on the original one-dimensional model for the external cavitating flow around a hydrofoil, this model is corrected according to the internal cavitating flow characteristics in the venturi tube. The results show that the original one-dimensional model ignores the choking effect of cavitating flow, which is obvious in a venturi tube with a narrow flow channel, thus leading to an inaccurate prediction of pressure fluctuation in the venturi tube. The modified model can significantly overcome its deficiencies and improve the accuracy of the pressure fluctuation prediction, providing a theoretical basis and guidance for engineering application to controlling the pressure fluctuation in a venturi tube or for other internal flows.展开更多
As a cable-stayed bridge with the longest main span, the Sutong Bridge faces the threat of typhoons every year. Based on field measured data measured at the top of the tower and at the mid-span by anemometers, Typhoon...As a cable-stayed bridge with the longest main span, the Sutong Bridge faces the threat of typhoons every year. Based on field measured data measured at the top of the tower and at the mid-span by anemometers, Typhoon Muifa is analyzed in detail to obtain the wind characteristics, including the mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence, etc. The correlated mean wind speeds at the two heights show the reliability of recorded wind data as well as the variation of wind speed with height. Turbulence inten- sities and gust factors fluctuate in a similar way. The values of inte- gral scales are sensitive in different case. The measured power spec- tra are particularly compared with Kaimal spectrum, Teunissen spectrum, Harris spectrum, and Davenport spectrum. The results show that the measured spectra cannot fit the code-suggested spectra very well, which exhibits the demand of more accurate spectra. Conclusions obtained in this article can provide references for wind resistance desima of suoer-long-soan cable-staved brides.展开更多
基金the Natural Science Foundation Committee of Guangdong Province(No.32220053)the National Key R&D Program of China(No.2017YFC1703800).
文摘The stem and branch extract of Tripterygium wilfordii(Celastraceae)afforded seven new dihydroagarofuran sesquiterpene polyesters[tripterysines A‒G(1‒7)]and eight known ones(8‒15).The chemical structures of these new compounds were established based on combinational analysis of HR-ESI-MS and NMR techniques.The absolute configurations of tripterysines A‒C(1‒3)and E‒G(5‒7)were determined by X-ray crystallographic analysis and circular dichroism spectra.All the compounds were screened for their inhibitory effect on inflammation through determining their inhibitory effect on nitric oxide production in LPS-induced RAW 264.7 cells and the secretion of inflammatory cytokines TNF-αand IL-6 in LPS-induced BV2 macrophages.Compound 9 exhibited significant inhibitory activity on NO production with an IC50 value of 8.77μmol·L−1.Moreover,compound 7 showed the strongest inhibitory effect with the secretion of IL-6 at 27.36%.
基金supported by the National Natural Science Foundation of China(Grant Nos.51679169,11472197)。
文摘The large eddy simulation(LES) method is used to simulate cavitating flow in a venturi tube. The simulated results agree fairly well with the experimental data. To quantitatively describe the relationship between cavitation evolution and excited pressure fluctuation in the venturi tube, a modified prediction model is proposed and its accuracy is verified by the LES results. Based on the original one-dimensional model for the external cavitating flow around a hydrofoil, this model is corrected according to the internal cavitating flow characteristics in the venturi tube. The results show that the original one-dimensional model ignores the choking effect of cavitating flow, which is obvious in a venturi tube with a narrow flow channel, thus leading to an inaccurate prediction of pressure fluctuation in the venturi tube. The modified model can significantly overcome its deficiencies and improve the accuracy of the pressure fluctuation prediction, providing a theoretical basis and guidance for engineering application to controlling the pressure fluctuation in a venturi tube or for other internal flows.
基金Supported by the National Natural Science Foundation of China(50908046,50978056)the Teaching and Scientific Research Fund for Excellent Young Teachers of Southeast University(3205001101)+1 种基金the Basic Scientific andResearch Fund of Southeast University(Seucx-201106)the Priority Academic Program Development Foundation of Jiangsu Higher Education Institutions,China
文摘As a cable-stayed bridge with the longest main span, the Sutong Bridge faces the threat of typhoons every year. Based on field measured data measured at the top of the tower and at the mid-span by anemometers, Typhoon Muifa is analyzed in detail to obtain the wind characteristics, including the mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence, etc. The correlated mean wind speeds at the two heights show the reliability of recorded wind data as well as the variation of wind speed with height. Turbulence inten- sities and gust factors fluctuate in a similar way. The values of inte- gral scales are sensitive in different case. The measured power spec- tra are particularly compared with Kaimal spectrum, Teunissen spectrum, Harris spectrum, and Davenport spectrum. The results show that the measured spectra cannot fit the code-suggested spectra very well, which exhibits the demand of more accurate spectra. Conclusions obtained in this article can provide references for wind resistance desima of suoer-long-soan cable-staved brides.
