Objective: To evaluate the in vitro cytotoxic activity of the fractionated extract as well as isolated compounds of Arum palaestinum Boiss.(A. palaestinum)(black calla lily), and to identify the volatile components wh...Objective: To evaluate the in vitro cytotoxic activity of the fractionated extract as well as isolated compounds of Arum palaestinum Boiss.(A. palaestinum)(black calla lily), and to identify the volatile components which may be responsible for the potential antitumor activity.Methods: A. palaestinum was collected from its natural habitats and subjected to phytochemical analysis for separation of pure compounds. In vitro cytotoxic activity was investigated against four human carcinoma cell lines Hep2, He La, Hep G2 and MCF7 for the fractionated extract and isolated compounds. While, the diethyl ether fraction was subjected to GC–MS analysis as it exhibited the most potent cytotoxic effect to evaluate the active constituents responsible for the cytotoxic activities.Results: Four flavonoid compounds were isolated(luteolin, chrysoeriol, isoorientin,isovitexin) from the diethyl ether and ethyl acetate. The extracts and the pure isolated compounds showed a significant high antiproliferative activity against all investigated cell lines. The GC–MS analysis revealed the separation and identification of 15 compounds representing 95.01% of the extract and belonging to different groups of chemical compounds.Conclusions: The present study is considered to be the first report on the cytotoxic activities carried out on different selected fractions and pure compounds of A. palaestinum to provide evidences for its strong antitumor activities. In addition,chrysoeriol and isovitexin compounds were isolated for the first time from the studied taxa.展开更多
This article explains why it is important to organize communicative activities in English teaching, as well as some theories and basic principles related to this respect. It is made up of four parts: 1) General Introd...This article explains why it is important to organize communicative activities in English teaching, as well as some theories and basic principles related to this respect. It is made up of four parts: 1) General Introduction; 2) How to organize communicative activities; 3) What educational objectives are to be reached through communicative activities and 4) Conclusion.The article is written to exchange ideas on organizing communicative activities in English classes with other English teachers as me.展开更多
This paper proposes an optimal dynamic reserve activation plan after the occurrence of an emergency situation （generator/transmission line outage, load increase or both）. An optimal plan is developed to handle the e...This paper proposes an optimal dynamic reserve activation plan after the occurrence of an emergency situation （generator/transmission line outage, load increase or both）. An optimal plan is developed to handle the emergency, using the coordinated action of fast and slow reserves, for secure operation with minimum overall cost. It considers the reserves supplied by the conventional thermal generators （spinning reserves）, hydro power units and load demands （demand-side reserves）. The optimal backing down of costly/fast reserves and bringing up of slow reserves in each sub-interval in an integrated manner is proposed. The proposed reserve activation approaches are solved using the genetic algorithm, and some of the simulation results are also compared using the Matlab optimization toolbox and the general algebraic modeling system （GAMS） software. The simulation studies are performed on the IEEE 30, 57 and 300 bus test systems. These results demonstrate the advantage of the proposed integrated/dynamic reserve activation plan over the conventional/sequential approach.展开更多
基金Support by Science and Technology Development Fund,with Grant No.4402
文摘Objective: To evaluate the in vitro cytotoxic activity of the fractionated extract as well as isolated compounds of Arum palaestinum Boiss.(A. palaestinum)(black calla lily), and to identify the volatile components which may be responsible for the potential antitumor activity.Methods: A. palaestinum was collected from its natural habitats and subjected to phytochemical analysis for separation of pure compounds. In vitro cytotoxic activity was investigated against four human carcinoma cell lines Hep2, He La, Hep G2 and MCF7 for the fractionated extract and isolated compounds. While, the diethyl ether fraction was subjected to GC–MS analysis as it exhibited the most potent cytotoxic effect to evaluate the active constituents responsible for the cytotoxic activities.Results: Four flavonoid compounds were isolated(luteolin, chrysoeriol, isoorientin,isovitexin) from the diethyl ether and ethyl acetate. The extracts and the pure isolated compounds showed a significant high antiproliferative activity against all investigated cell lines. The GC–MS analysis revealed the separation and identification of 15 compounds representing 95.01% of the extract and belonging to different groups of chemical compounds.Conclusions: The present study is considered to be the first report on the cytotoxic activities carried out on different selected fractions and pure compounds of A. palaestinum to provide evidences for its strong antitumor activities. In addition,chrysoeriol and isovitexin compounds were isolated for the first time from the studied taxa.
文摘This article explains why it is important to organize communicative activities in English teaching, as well as some theories and basic principles related to this respect. It is made up of four parts: 1) General Introduction; 2) How to organize communicative activities; 3) What educational objectives are to be reached through communicative activities and 4) Conclusion.The article is written to exchange ideas on organizing communicative activities in English classes with other English teachers as me.
文摘This paper proposes an optimal dynamic reserve activation plan after the occurrence of an emergency situation （generator/transmission line outage, load increase or both）. An optimal plan is developed to handle the emergency, using the coordinated action of fast and slow reserves, for secure operation with minimum overall cost. It considers the reserves supplied by the conventional thermal generators （spinning reserves）, hydro power units and load demands （demand-side reserves）. The optimal backing down of costly/fast reserves and bringing up of slow reserves in each sub-interval in an integrated manner is proposed. The proposed reserve activation approaches are solved using the genetic algorithm, and some of the simulation results are also compared using the Matlab optimization toolbox and the general algebraic modeling system （GAMS） software. The simulation studies are performed on the IEEE 30, 57 and 300 bus test systems. These results demonstrate the advantage of the proposed integrated/dynamic reserve activation plan over the conventional/sequential approach.
