In this work,an electronic nose was used to evaluate the different cultivars and mature stages of melons,so as to establish a scientific method to accurately distinguish the maturity and varieties of melons. Principal...In this work,an electronic nose was used to evaluate the different cultivars and mature stages of melons,so as to establish a scientific method to accurately distinguish the maturity and varieties of melons. Principal component analysis (PCA) and linear discriminant analysis (LDA ) showed that immature melons could be well distinguished from mature melons using electronic nose. When PCA method was used to analyze,electronic nose could completely classify and identify the maturity of melons. Meanwhile,the electronic nose could distinguish different varieties of melons with high discrimination value. The flavor of samples under cut or no cut conditions would slightly change,leading to the variation of discrimination value among different varieties. The samples with similar flavor under no cut condition could be analyzed through cutting mode. The research built a rapid and accurate method to judge the maturity of melons instead of man sense.展开更多
DNA-based approaches to systematics have changed dramatically during the last two decades with the rise of DNA barcoding methods and newer multi-locus methods for species delimitation. During the last half-decade, par...DNA-based approaches to systematics have changed dramatically during the last two decades with the rise of DNA barcoding methods and newer multi-locus methods for species delimitation. During the last half-decade, partly driven by the new sequencing technologies, the focus has shifted to multi-locus sequence data and the identification of species within the frame-work of the multi-species coalescent （MSC）. In this paper, I discuss model-based Bayesian methods for species delimitation that have been developed in recent years using the MSC. Several approximate methods for species delimitation （and their limitations） are also discussed. Explicit species delimitation models have the advantage of clarifying more precisely what is being delimited and what assumptions we are making in doing so. Moreover, the methods can be very powerful when applied to large multi-locus datasets and thus take full advantage of data generated using today＇s technologies [Current Zoology 61 （5）： 846-853,2015].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
基金Supported by National Natural Science Foundation of China(30870109)
文摘In this work,an electronic nose was used to evaluate the different cultivars and mature stages of melons,so as to establish a scientific method to accurately distinguish the maturity and varieties of melons. Principal component analysis (PCA) and linear discriminant analysis (LDA ) showed that immature melons could be well distinguished from mature melons using electronic nose. When PCA method was used to analyze,electronic nose could completely classify and identify the maturity of melons. Meanwhile,the electronic nose could distinguish different varieties of melons with high discrimination value. The flavor of samples under cut or no cut conditions would slightly change,leading to the variation of discrimination value among different varieties. The samples with similar flavor under no cut condition could be analyzed through cutting mode. The research built a rapid and accurate method to judge the maturity of melons instead of man sense.
文摘DNA-based approaches to systematics have changed dramatically during the last two decades with the rise of DNA barcoding methods and newer multi-locus methods for species delimitation. During the last half-decade, partly driven by the new sequencing technologies, the focus has shifted to multi-locus sequence data and the identification of species within the frame-work of the multi-species coalescent （MSC）. In this paper, I discuss model-based Bayesian methods for species delimitation that have been developed in recent years using the MSC. Several approximate methods for species delimitation （and their limitations） are also discussed. Explicit species delimitation models have the advantage of clarifying more precisely what is being delimited and what assumptions we are making in doing so. Moreover, the methods can be very powerful when applied to large multi-locus datasets and thus take full advantage of data generated using today＇s technologies [Current Zoology 61 （5）： 846-853,2015].
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.
