Prosopis farcta, a plant belongs to the mimosoideae, is characterized by a very wide spectrum of various bioactive and medical constituents. Vitexin, the marker flavonoid found in Prosopis, has potent and broad antitu...Prosopis farcta, a plant belongs to the mimosoideae, is characterized by a very wide spectrum of various bioactive and medical constituents. Vitexin, the marker flavonoid found in Prosopis, has potent and broad antitumour efficacy in preclinical models. Many studies had been done for the isolation of flavonoids (vitexin) by completely different chromatographically methodology. During this study, vitexin was isolated from Prosopis farcta by 6 different extraction methods in which parameters as the type, concentration and pH of the extracting solvents considered. Among different solvent systems used, methanol-water (40%, containing acetic acid 0.5%) was found to be the best solvent generating the highest yield (0.554 mg·g-1 DW) from Prosopis leaves. The present work suggests an efficient method for estimation the greatest content of vitexin analyzed by HPLC technique and introduces Prosopis farcta as a suitable source of this flavonoid with several pharmacological properties.展开更多
Wireless sensor actor networks are composed of sensor and actor nodes wherein sensor nodes outnumber resource-rich actor nodes. Sensor nodes gather information and send them to a central node (sink) and/or to actors f...Wireless sensor actor networks are composed of sensor and actor nodes wherein sensor nodes outnumber resource-rich actor nodes. Sensor nodes gather information and send them to a central node (sink) and/or to actors for proper actions. The short lifetime of energy-constrained sensor nodes can endanger the proper operation of the whole network when they run out of power and partition the network. Energy harvesting as well as minimizing sensor energy consumption had already been studied. We propose a different approach for recharging sensor nodes by mobile actor nodes that use only local information. Sensor nodes send their energy status along with their sensed information to actors in their coverage. Based on this energy information, actors coordinate implicitly to decide on the timings and the ordering of recharges of low energy sensor nodes. Coordination between actors is achieved by swarm intelligence and the replenishment continues during local learning of actor nodes. The number of actors required to keep up such networks is identified through simulation using VisualSense. It is shown that defining the appropriate number of actor nodes is critical to the success of recharging strategies in prolonging the network lifetime.展开更多
Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews ...Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews the recent approaches that have been introduced and used for cloud service brokerage and discusses their challenges accordingly. We propose a set of attributes for a CSB to be considered effective. DifFerent CSBs' approaches are classified as either single service or multiple service models. The CSBs are then assessed, analyzed, and compared with respect to the proposed set of attributes. Based on our studies, CSBs with multiple service models that support more of the proposed effective CSB attributes have wider application in cloud computing environments.展开更多
文摘Prosopis farcta, a plant belongs to the mimosoideae, is characterized by a very wide spectrum of various bioactive and medical constituents. Vitexin, the marker flavonoid found in Prosopis, has potent and broad antitumour efficacy in preclinical models. Many studies had been done for the isolation of flavonoids (vitexin) by completely different chromatographically methodology. During this study, vitexin was isolated from Prosopis farcta by 6 different extraction methods in which parameters as the type, concentration and pH of the extracting solvents considered. Among different solvent systems used, methanol-water (40%, containing acetic acid 0.5%) was found to be the best solvent generating the highest yield (0.554 mg·g-1 DW) from Prosopis leaves. The present work suggests an efficient method for estimation the greatest content of vitexin analyzed by HPLC technique and introduces Prosopis farcta as a suitable source of this flavonoid with several pharmacological properties.
文摘Wireless sensor actor networks are composed of sensor and actor nodes wherein sensor nodes outnumber resource-rich actor nodes. Sensor nodes gather information and send them to a central node (sink) and/or to actors for proper actions. The short lifetime of energy-constrained sensor nodes can endanger the proper operation of the whole network when they run out of power and partition the network. Energy harvesting as well as minimizing sensor energy consumption had already been studied. We propose a different approach for recharging sensor nodes by mobile actor nodes that use only local information. Sensor nodes send their energy status along with their sensed information to actors in their coverage. Based on this energy information, actors coordinate implicitly to decide on the timings and the ordering of recharges of low energy sensor nodes. Coordination between actors is achieved by swarm intelligence and the replenishment continues during local learning of actor nodes. The number of actors required to keep up such networks is identified through simulation using VisualSense. It is shown that defining the appropriate number of actor nodes is critical to the success of recharging strategies in prolonging the network lifetime.
文摘Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews the recent approaches that have been introduced and used for cloud service brokerage and discusses their challenges accordingly. We propose a set of attributes for a CSB to be considered effective. DifFerent CSBs' approaches are classified as either single service or multiple service models. The CSBs are then assessed, analyzed, and compared with respect to the proposed set of attributes. Based on our studies, CSBs with multiple service models that support more of the proposed effective CSB attributes have wider application in cloud computing environments.
