Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacen...Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.展开更多
OBJECTIVE: To assess the phytochemical contents and antioxidant activities of crude extracts from selected Tulbaghia species.METHODS: Standard methods were used for preliminary phytochemical analysis. The total phenol...OBJECTIVE: To assess the phytochemical contents and antioxidant activities of crude extracts from selected Tulbaghia species.METHODS: Standard methods were used for preliminary phytochemical analysis. The total phenolic acid contents of the plant extracts were determined using the Folin-Ciocalteu method, and the total flavonoid contents were determined using the aluminum chloride colorimetric method. 1,1-Diphenyl-2-picrylhydrazyl and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assays were used to evaluate the antioxidant activities.RESULTS: Phytochemical screening showed flavonoids, glycosides, tannins, terpenoids, saponins,and steroids were present in the Tulbaghia species.The total phenolic acid and flavonoid contents varied in the different plant extracts, ranging from4.50 to 11.10 mg of gallic acid equivalents per gram of fresh material and 3.04 to 9.65 mg of quercetin equivalents per gram, respectively. The IC50 values determined for Tulbaghia alliacea and Tulbaghia violacea based on 1,1-diphenyl-2-picrylhydrazyl(0.06 and 0.08 mg/m L, respectively) and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)(0.06 and 0.03 mg/m L, respectively) were low and showed they had potential antioxidant activities.CONCLUSION: Our results suggest that individual compounds from Tulbaghia species should be isolated for analysis of their antioxidant activity because some compounds may work best when pure.展开更多
文摘Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.
基金Supported by Vaal University of Technology,Private Bag X021,Vanderbijlpark 1900,South Africa
文摘OBJECTIVE: To assess the phytochemical contents and antioxidant activities of crude extracts from selected Tulbaghia species.METHODS: Standard methods were used for preliminary phytochemical analysis. The total phenolic acid contents of the plant extracts were determined using the Folin-Ciocalteu method, and the total flavonoid contents were determined using the aluminum chloride colorimetric method. 1,1-Diphenyl-2-picrylhydrazyl and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assays were used to evaluate the antioxidant activities.RESULTS: Phytochemical screening showed flavonoids, glycosides, tannins, terpenoids, saponins,and steroids were present in the Tulbaghia species.The total phenolic acid and flavonoid contents varied in the different plant extracts, ranging from4.50 to 11.10 mg of gallic acid equivalents per gram of fresh material and 3.04 to 9.65 mg of quercetin equivalents per gram, respectively. The IC50 values determined for Tulbaghia alliacea and Tulbaghia violacea based on 1,1-diphenyl-2-picrylhydrazyl(0.06 and 0.08 mg/m L, respectively) and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)(0.06 and 0.03 mg/m L, respectively) were low and showed they had potential antioxidant activities.CONCLUSION: Our results suggest that individual compounds from Tulbaghia species should be isolated for analysis of their antioxidant activity because some compounds may work best when pure.
