简介:Thispaperpresentedaninterestingnanoparticle-baseddrugdeliverysystemwithmorphologytransitionbehaviordependingonthecontentofexposedPEGchainontheparticlesurface,whichisadjustablebyadditionofdifferentamountofcyclodextrin(a-CD).Theeffectofa-CDinclusiontotheself-assemblybehaviorofmethoxypolyethyleneglycol(mPEG)graftedchitosan(CS)wasstudied.TheresultsshowedthatthemPEGgraftedchitosan(mPEG-[9_TD$IF]g-CS)formsself-assemblednanoparticleswitheithermicelleorhollowspheremorphologydependingontheratioofa-CDtomPEG,ascharacterizedbyatomicforcemicroscopy(AFM),transmissionelectronmicroscopy(TEM),andX-raydiffraction(XRD).Theirsizesandzetapotentialincreasedfrom257.6nmto768.2nmandfrom+4.5mVto+11.6mV,respectively,withtheincreasingamountofa-CD.Thecorrelationbetweenzetapotentialandparticlesizeofa-CD/mPEG-[9_TD$IF]g-CSnanoparticlesindicatedvariedPEGdensityonsurfaceofnanoparticles.Basedontheaboveexperimentalobservations,alikelymechanismforthemorphologicaltransitionoftherod-coilgraftcopolymermPEG-[9_TD$IF]g-CSwasproposed.
简介:介绍了DirectShow技术,并用该技术实现了一个基于MPEG-4的网络视频监控系统,包括多媒体数据的捕捉、解码、回放、定位等功能.基于DirectShow框架的构建方式极大地简化了复杂的多媒体程序的开发,同时实现了视频监控系统对实时性和清晰度可调的要求,为MPEG-4应用提供了一套完整的解决方案.
简介:Futuremultimediacommunicationsystemshavetosupporttheuser'sneeds,theterminalcapabilities,thecontentspecificationandtheunderlyingnetworkingtechnologies.Therelatedprotocolsandapplicationsmustbedesignedfromthisintegrationperspectiveinacross-layercentricmanner.Inthispaper,weproposeanimplementationofastreamingservice(e.g.,TelevisionoverIPservice)withaunifiedQoSmanagementconceptthatenablesanIPdrivenintegrationofdifferentsystemcomponents(terminal,user,content,andnetwork).TheMPEG-21frameworkisusedtoprovideacommonsupportforimplementingandmanagingtheend-to-endQoS.Themainfocusofthispaperisonthearchitecturedesign,protocolsspecificationandimplementationevaluation.PerformanceevaluationsusingPSNRandSSIMobjectivevideoqualitymetricsshowthebenefitoftheproposedMPEG-21-enabledcross-layeradaptation.
简介:针对数字网络视频监撞系统的索求,研制了一种基于MPEG-4网络视频服务器.采用ATglRM9200芯片作为嵌入式CPU芯片,GO7007SB芯片作为MPEG-4硬件压缩芯片.从系统的硬件设计和软件设计2部分介绍了系统的音视频采集、压缩、存储、传愉及系统拉制等方面设计.实验证明,该系统性能德定、使用灵活,在视频监控、视频会议等各个领城中将会有广泛的应用前景.