Preparation and Evaluation of Electrospun Zein/HA Fibers Based on Two Methods of Adding HA Nanoparticles

Zein/HA fibrous membranes were successfully prepared by electrospinning the zein/HA solution mixed by magnetic stirrer （Method I） or ultrasonic power （Method Ⅱ）. The morphology of zeirdHA nanocomposite fibers and the distribution of HA within the fibers electrospun by two methods were researched by Scanning Electron Microscopy （SEM） and Energy-dispersive X-ray spectroscopy （EDX）. In Method I, the distribution of HA nanoparticles is not homogeneous and HA particles tend to agglom- erate. The relatively homogeneous HA distribution can be observed in the membranes electrospun by Method Ⅱ. Using mag- netic stirrer to prepare the electrospinning solution improves the wettability of zein/HA membranes. From the viewpoint of application, electrospun zein/HA membranes fabricated by the solution mixed via Methods I and II both possessed reasonable tensile strength and elongation at break for both handling and sterilization. Considering two aspects of strength and elongation, electrospun zein/HA membranes fabricated by Method I are more balanced than those fabricated by Method Ⅱ. Biological performances of the control zein and zein/HA membranes were assessed by in vitro culture of hMSCs. Results show that both types of the membranes can support cell proliferation. The cells cultured on the zein/HA membranes electrospun by Method I with 5 wt% HA （on weight ofzein） show significantly higher proliferation than those cultured on the control zein membranes on the seventh day. The electrospun zein/HA fibrous membranes show promises for bone tissue engineering applications.

Preparation and Characterization of Paclitaxel/Chitosan Nanosuspensions for Drug Delivery System and Cytotoxicity Evaluation In Vitro

In this study,we prepared paclitaxel/chitosan(PTX/CS)nanosuspensions(NSs)with different mass ratios of PTX and CS(1.5:2,2:2,and 2.5:2),for controlled drug delivery purposes.For attachment and dispersion in water medium,a simple ultrasonic disruption technique was employed.The water-dispersed PTX/CS NSs exhibited a rod-shape morphology with an average diameter of 170-210 nm and average length of about 1-10μm.Transmission electron microscopy,differential scan-ning calorimetry and X-ray diffraction indicated that the obtained PTX/CS NSs contain a nanocrystalline PTX phase.It was also inferred that presence of CS can promotes the crystalline nature of PTX up to 80%.In addition,efficiency of PTX loading reached over 85%in freeze-dried PTX/CS NSs,showing a slow rate of drug release in vitro for 8 days.The MTT and LDH assessments revealed that PTX/CS NSs significantly inhibit the growth of tumor cells(HeLa),while it is slightly toxic for the normal cells(NIH/3T3).Therefore,PTX/CS NSs is suggested as a potential nanodrug delivery system for cancer therapy.

Design of Personal Terminal DNS Agent

As one of the most important Internet infrastructures,domain name system(DNS)is vulnerable to various attacks,and the issue of DNS security has received critical attention.However,most of the existing DNS security enhancements have encountered great difficulties in the process of popularization.The main reason is that these enhancement measures usually focus on the server side,thus requiring changes to existing DNS protocol or architecture,while modifying the Internet infrastructure is inherently hard.Noticing that the range of domain name frequently visited by a single user is much smaller than the entire domain system,in this paper we propose the idea of personal DNS agent(P-DNS),which migrates DNS security from servers to user terminals and can be applied without changing the current DNS infrastructure.P-DNS takes advantage of static and dynamic redundancy to enhance DNS security.Specifically,in the static redundancy phase,P-DNS improves the resolution efficiency by utilizing resolution results cached in LDAP.While in the dynamic redundancy stage,F-DNS improves the reliability of resolution results by querying multiple recursive name servers(RNSs).Simulation results show that our proposed architecture can effectively improve DNS security performance and greatly reduce the additional delay caused by redundancy.