Dynamic fault tree analysis is widely used for the reliability analysis of the complex system with dynamic failure characteristics. In many circumstances, the exact value of system reliability is difficult to obtain d...Dynamic fault tree analysis is widely used for the reliability analysis of the complex system with dynamic failure characteristics. In many circumstances, the exact value of system reliability is difficult to obtain due to absent or insufficient data for failure probabilities or failure rates of components. The traditional fuzzy operation arithmetic based on extension principle or interval theory may lead to fuzzy accumulations. Moreover, the existing fuzzy dynamic fault tree analysis methods are restricted to the case that all system components follow exponential time-to-failure distributions. To overcome these problems, a new fuzzy dynamic fault tree analysis approach based on the weakest n-dimensional t-norm arithmetic and developed sequential binary decision diagrams method is proposed to evaluate system fuzzy reliability. Compared with the existing approach,the proposed method can effectively reduce fuzzy cumulative and be applicable to any time-tofailure distribution type for system components. Finally, a case study is presented to illustrate the application and advantages of the proposed approach.展开更多
β-elemene is an effective anti-cancer component which has been widely used in clinic.However,it still relies on the extraction from the Chinese medicine plant Curcuma wenyujin,which seriously limits its application.S...β-elemene is an effective anti-cancer component which has been widely used in clinic.However,it still relies on the extraction from the Chinese medicine plant Curcuma wenyujin,which seriously limits its application.Synthetic biology offers a promising approach to satisfy its supply.β-elemene is derived from germacrene A(GA),which is synthesized by germacrene A synthase(GAS),through Cope rearrangement under heat condition instead of enzymatic reaction.In this study,an effective germacrene A synthase(ScGAS)was identified from Solidago canadensis which could produce GA when expressed in E.coli.By introducing the heterogeneous MVA pathway to enrich the FPP pool,the strain yielded 147 mg/L of GA in shake flasks which represented 2.98-fold improvement over the initial one.Moreover,combining molecular docking with phylogeny analysis of ScGAS largely narrowed down the category of its key residues’mutagenesis.The Y376L mutant showed the highest yield of 487 mg/L which was almost 10-fold higher than the initial yield.These results indicate that diverting the metabolism of the host and enzyme mutagenesis based on the combination of molecular docking and phylogeny analysis are of great value to constructing terpenoids chassis.展开更多
基金supported by the National Defense Basic Scientific Research program of China (No.61325102)
文摘Dynamic fault tree analysis is widely used for the reliability analysis of the complex system with dynamic failure characteristics. In many circumstances, the exact value of system reliability is difficult to obtain due to absent or insufficient data for failure probabilities or failure rates of components. The traditional fuzzy operation arithmetic based on extension principle or interval theory may lead to fuzzy accumulations. Moreover, the existing fuzzy dynamic fault tree analysis methods are restricted to the case that all system components follow exponential time-to-failure distributions. To overcome these problems, a new fuzzy dynamic fault tree analysis approach based on the weakest n-dimensional t-norm arithmetic and developed sequential binary decision diagrams method is proposed to evaluate system fuzzy reliability. Compared with the existing approach,the proposed method can effectively reduce fuzzy cumulative and be applicable to any time-tofailure distribution type for system components. Finally, a case study is presented to illustrate the application and advantages of the proposed approach.
基金the National Natural Science Foundation of China(No.32360111)Science Fund for Distinguished Young Scholars of Jiangxi Province(No.20224ACB215004)+2 种基金Key Research and Development Program of Jiangxi Province(No.20243BBI91010)Open Project Program of Shanghai Key Laboratory of Plant Functional Genomics and Resources(No.PFGR202303)B.M.Feng acknowledges the Key Research and Development Program of Dalian(No.2021YF18SN024)。
文摘β-elemene is an effective anti-cancer component which has been widely used in clinic.However,it still relies on the extraction from the Chinese medicine plant Curcuma wenyujin,which seriously limits its application.Synthetic biology offers a promising approach to satisfy its supply.β-elemene is derived from germacrene A(GA),which is synthesized by germacrene A synthase(GAS),through Cope rearrangement under heat condition instead of enzymatic reaction.In this study,an effective germacrene A synthase(ScGAS)was identified from Solidago canadensis which could produce GA when expressed in E.coli.By introducing the heterogeneous MVA pathway to enrich the FPP pool,the strain yielded 147 mg/L of GA in shake flasks which represented 2.98-fold improvement over the initial one.Moreover,combining molecular docking with phylogeny analysis of ScGAS largely narrowed down the category of its key residues’mutagenesis.The Y376L mutant showed the highest yield of 487 mg/L which was almost 10-fold higher than the initial yield.These results indicate that diverting the metabolism of the host and enzyme mutagenesis based on the combination of molecular docking and phylogeny analysis are of great value to constructing terpenoids chassis.
