Preparation and evaluation of 2-methoxyestradiol-loaded pH-sensitive liposomes

The development and clinical application of 2-methoxyestradiol (2-ME) as a new type of antitumor drug are limited due to its poor solubility, rapid metabolism in vivo, and large oral dosage. 2-ME-loaded pHsensitive liposomes (2-ME-PSLs) was prepared containing the lipids, Lipoid E-80 (E-80), cholesteryl hemisuccinate (CHEMS), and cholesterol (CHOL) via thin-film ultrasonic dispersion. First, preparation conditions of 2-ME-PSLs were optimized by orthogonal test. Then 2-ME-PSL was characterized, and the release behavior and stability of 2-ME-PSL in vitro were evaluated. The optimal preparation conditions for 2-ME-PSLs were as follows: 2-ME : E-80+CHEMS 1:15; CHOL : E-80+CHEMS 1:5; ultrasonication time 20 minutes. The mean particle size, PDI, zeta potential, and entrapment efficiency (EE) of 2-MEPSLs were 116 ± 9 nm, 0.161 ± 0.025, −22.4 ± 1.7 mV, and 98.6 ± 0.5%, respectively. As viewed under a transmission electron microscope, 2-ME-PSLs were well dispersed and almost spherical. They exhibited significant pH-sensitive properties and were fairly stable when diluted with a physiological solution. In conclusion, 2-ME-PSLs were successfully prepared and possessed a favorable pH sensitivity and good dissolution stability with a normal solution

Overlay Networks for Global Reputation Aggregation

Abstract: This paper presents a new approach to trusted Grid computing in a Peer-to-Peer (P2P) setting. Trust and security in P2P Grids are essential to establish lasting working relationships among the peers joining collective Grid applications. A P2P reputation system is thus needed to collect peer trust scores and aggregates them to yield a global reputation. We use a new trust overlay network (TON) to model the trust relationships among the peers. After analyzing the eBay transaction trace data, we discover a power-law distribution in user feedbacks. This power law is proven applicable to any dynamic P2P systems. We develop a new P2P reputation system, PowerTrust, to leverage on the power-law feedback characteristics. The PowerTrust system is built with locality-preserving hash functions and a lookahead random walk strategy. Dynamic system reconfiguration is enabled by the use of power nodes with well-established reputations. This power-node approach significantly reduces the aggregation overhead. Through P2P simulation experiments on distributed file sharing and Grid parameter-sweeping applications (PSA) applications, we demonstrate the advantages of fast reputation convergence and accurate ranking of peer reputations. Simulated P2P Grid performance results are reported with enhanced P2P query success rate, job makespan and job success rate, after security binding with the reputation system in scalable P2P Grid applications Keyword: Peer-to-Peer systems, Grid computing, overlay network, trust management, distributed hash table, reputation system, distributed file sharing, and parameter sweeping applications (PSA). 1

Optimal Placement of Virtual Masses for Structural Damage Identification

Adding virtual masses to a structure is an efficient way to generate a large number of natural frequencies for damage identification. The influence of a virtual mass can be expressed by Virtual Distortion Method (VDM) using the response measured by a sensor at the involved point. The proper placement of the virtual masses can improve the accuracy of damage identification, therefore the problem of their optimal placement is studied in this paper. Firstly, the damage sensitivity matrix of the structure with added virtual masses is built. The Volumetric Maximum Criterion of the sensitivity matrix is established to ensure the mutual independence of measurement points for the optimization of mass placement. Secondly, a method of sensitivity analysis and error analysis is proposed to determine the values of the virtual masses, and then an improved version of the Particle Swarm Optimization (PSO) algorithm is proposed for placement optimization of the virtual masses. Finally, the optimized placement is used to identify the damage of structures. The effectiveness of the proposed method is verified by a numerical simulation of a simply supported beam structure and a truss structure

NAM: A network adaptable middleware to enhance response time of web services

Web Services is an emerging software technology that is based on the concept of software and data as a service. Binary and XML are two popular encoding/decoding mechanisms for network messages. A Web Service may employ a loss-less compression technique (e.g., Zip, XMill, etc.) in order to reduce message size prior to its transmission across the network, minimizing its transmission time. This saving might be outweighed by the overhead of compressing the output of a Web Service at a server and decompressing it at a client. The primary contribution of this paper is NAM, a middleware that strikes a compromise between these two factors in order to enhance response time. NAM decides when to compress data, based on the available client and server processor speeds and network characteristics. When compared with today\u27s common practice to transmit the output of a Web Service uncompressed always, our experimental results show NAM either provides similar or significantly improved response times (at times, more than 90% improvement) with Internet connections that offer bandwidths ranging from 80 to 100 Mbps. © 2008, IGI Global

NAM: A network adaptable middleware to enhance response time of web services

Web Services is an emerging software technology that is based on the concept of software and data ax a service. Binary and XML are two popular encoding/decoding mechanisms for network messages. A Web Service may employ a loss-less compression technique (e.g., Zip, XMill, etc.) in order to reduce message size prior to its transmission across the network, minimizing its transmission time. This saving might be outweighed by the overhead of compressing the output of a Web Service at a server and decompressing it at a client. The primary contribution of this paper is NAM, a middleware that strikes a compromise between these two factors in order to enhance response time. NAM decides when to compress data, based on the available client and server processor speeds and network characteristics. When compared with today\u27s common practice to transmit the output of a Web Service uncompressed always, our experimental results show NAM either provides similar or significantly improved response times (at times, more than 90% improvement) with Internet connections that offer bandwidths ranging from 80 to 100 Mbps. Copyright © 2005, Idea Group Inc