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纳米羟基磷灰石/聚酰胺66仿生复合材料的非等温结晶动力学研究

关键词:纳米羟基磷灰石,聚酰胺66仿生复合材料,非等温结晶动力学,Mo法

本文着者李玉宝等人将水热合成的及常压下自制的纳米级羟基磷灰石(nHA)浆料与聚酰胺66在溶剂中复合,得到了与自然骨结构相似,强度和模量相匹配的nHA/PA66纳米仿生复合材料.该复合材料克服了单纯羟基磷灰石生物陶瓷脆性大,强度差,不易成型等缺点,在提高材料的韧性和力学性能的同时,保持了该复合材料良好的生物相容性和生物活性.动物实验和临床验证表明,nHA/PA66复合材料在修复骨缺损,作为骨水泥治疗骨质疏松等方面具有很好的应用前景.

关于纳米羟基磷灰石增强聚酰胺66的仿生复合材料结晶行为的研究,本文采用差示扫描量热仪(DSC)研究了nHA/PA66纳米复合材料的非等温结晶行为,并将其与纯PA66的结晶行为进行了比较.得出以下结论:

(1)纳米羟基磷灰石的加入,一方面起到了异相成核剂的作用,提高了PA66的结晶速率,另一方面,由于纳米羟基磷灰石与聚酰胺之间的强界面作用,阻碍了聚酰胺分子的有序排列,降低了PA66的结晶度.

(2)随着降温速率的增加,PA66和nHA/PA66复合材料的结晶峰都从高温向低温移动,而且结晶峰变宽,表明它们的结晶的范围随降温速率的增加而变宽.

(3)采用Mo法来处理纳米羟基磷灰石/聚酰胺66复合材料的非等温结晶行为,lgR和lgt之间的线性关系好.同一组材料的a值基本上接近,F(T)的值则随着复合材料的结晶度的增加而增加.F(T)值大,表明在相同的时间内,对于同一种材料要使其相对结晶度越大,则需提高其冷却速率.

摘自《功能材料》2005年04期

羟基磷灰石/胶原类骨仿生复合材料的制备及表征

关键词:羟基磷灰石,胶原,生物矿化,自组装

本文中研究体外模拟天然骨生物矿化和材料自组装的形成机制,制备羟基磷灰石/胶原(HAp/Col)类骨仿生复合材料.合成HAp/Col仿生复合材料时,在与人体生理环境相似的条件下,钙磷盐以胶原分子为模板通过自组装在胶原分子表面直接矿化成核,胶原分子三螺旋结构外侧的COO-和HAp晶体表面的Ca2+间通过静电相互作用,使HAp按其c轴与胶原纤维分子纵向平行排列.Ca表面电子的结合状态是与HAp的两个PO3-4基团及Col分子表面的RCOO-配位成键,Ca2+—COO-键的结合能比Ca2+—PO3-4无机键的结合能要大,因为有机键兼有离子键和共价键的特点.Ca2+与RCOO-配位削弱了C等于O双键而使Ca—O化学键增强.胶原上COO-成为能与Ca2+配位形成离子化合物特别活跃的位点,这些离子化合物由于过饱和效应进一步与PO3-4作用形成具有临界尺度的晶核,随后HAp开始生长成具有规则取向且结晶度低的纳米晶体,矿化的胶原微纤维继续组装成多级结构.本文中制备的类骨仿生材料为Col纤维增韧的HAp/Col复合体,湿态加压干燥后形成具有一定韧性的块状结构.但由于天然骨具备从微观,亚微观到宏观的多级结构,可以对该材料交联处理或与其它聚合物复合成型为类骨修复材料.

本文中根据生物矿化原理,利用材料自组装技术制备出了羟基磷灰石/胶原仿生复合材料.通过对材料的表征及实验证明:该复合材料在成分和纳米结构上与天然骨类似,利用生物系统在分子水平上储存和加工信息的作用可在体外模拟天然骨生物矿化和自组装机制制备出羟基磷灰石/胶原类骨仿生复合材料,通过进一步成型处理有望形成更接近天然骨的修复材料用于骨组织工程.

摘自:《复合材料学报》2005年02期

无序一维三元光子晶体的能带特性研究

关键词:

声波的负折射

关键词:

准周期结构一维光子晶体的透射谱

关键词:准周期结构,一维光子晶体,透射谱

光子晶体具有许多独特性质:如光子禁带,抑制自发辐射,光子局域化,偏振特性等,自1987年提出光子晶体概念至今,对光子晶体的研究取得了令人鼓舞的成果,同时在应用方面也取得了很大进展.例如光子晶体波导,光子晶体光纤,光子晶体微腔和光子晶体偏振器等.由于一维光子晶体易于实现以及其独特的传输特性,在光限幅器,双稳特性和光开关等方面都取得了成功.以上研究及结果都是建立在周期性电介质分布基础上的.近年来已经开始对准周期性电介质分布进行了研究.所谓准周期分布就是每个周期的各层光学厚度都作有规律的变化.准周期性光子晶体相对于周期性光子晶体,其光波传输特性有一定的变化.而这些传输特性的变化对于拓展光子晶体的应用有很大价值.因此我们对准周期一维光子晶体中光波的传输特性进行研究,以期取得新的应用.

提出了折射率和层厚分别递增或递减的准周期一维光子晶体结构,并用传输矩阵计算了此类准周期光子晶体的透射谱,其光子带隙均相对于周期性光子晶体带隙产生了移动.当折射率递变时,移动方向与递变符号有关.当层厚递变时,光子带隙均向长波方向移动.光子带隙移动量的大小随周期数的增加而增加.

本文提出的准周期性结构一维光子晶体所具有的透射特性(带隙特性),相对于周期性一维光子晶体的透射特性有了较大变化,其变化规律并不遵循周期性结构的变化规律,因此,研究准周期结构一维光子晶体的带隙规律,对于拓展其应用是极其重要的.研究发现每层光学厚度的递变即使相同,n固定d递变与d固定n递变所引起的带隙特性变化规律也是不同的,应该分别给予研究.这些变化规律对于滤波技术,反射器等都是极有价值的.

摘自:《江苏工业学院学报》2005年01期

一维金属/介质光子晶体用于BaF2晶体闪烁光谱修饰

关键词:光子晶体,BaF2闪烁晶体,光谱修饰

光子晶体是一种高低折射率材料交替排列的周期性结构,它首先在信息通讯领域具有巨大的应用前景对适用于该领域的光子晶体的大量研究表明,由于位移场的重新分布,包含有金属成分的光子晶体可呈现出非常宽的截止带,以及良好的全方向反射特性,由金属所引起的吸收损耗则可通过共振隧穿效应而得到有效降低以高折射/低折射/金属/低折射材料为周期的光子晶体结构,由于将金属层的总厚度分解至各周期之中,可以在高频区出现有趣的增加透射的现象,同时在低频区仍保持优良的反射特性对应相同的能带结构,采用金属/介质结构的光子晶体还可使总的层数小于全介质结构,以降低工艺制备要求本文提出了利用金属/介质光子晶体对BaF2晶体闪烁光谱进行修饰,通过在BaF2晶体表面制备具有合适能隙结构的光子晶体,使其在快成分位置形成较强的透射能带,在慢成分位置则形成宽的截止能带,从而有效地提高闪烁光快慢成分的相对比例.

利用光子晶体方法抑制BaF2晶体的闪烁光慢成分,可对BaF2晶体的发射光谱进行很好的修饰所设计的金属/介质光子晶体在紫外真空紫外区具有在短波范围高的透射带,在长波范围深的截止带,而且在透射带和截止带的过渡区可以具有陡峭的边缘通过选择不同的光子晶体的设计参量,如周期数,金属层的厚度等,可使快成分的衰减小于5倍,对慢成分的相对抑制比大于20倍采用适当的探测角度范围,可进一步使相对抑制比提高到100以上.

摘自:《光子学报》2005年01期

光子晶体光纤的纤芯等效半径分析

关键词:光子晶体光纤,等效芯半径,光束传播法,模色散方程

应用有限差分光束传播法和平面波展开法分别计算得到光子晶体光纤的基模有效折射率和包层有效折射率,结合阶跃折射率光纤的模色散方程解出该结构的等效芯半径.通过对不同结构下光子晶体光纤的研究,找到其等效芯半径随结构参数的变化规律,并根据计算结果将此规律以近似公式的形式给出该分析和结果可为利用有效折射率法分析光子晶体光纤时等效芯半径的选取提供一定的理论依据.

本文针对目前我们正在研制的塑料光子晶体光纤,分别采用有限差分光束传播法(finite-differencebeampropagationmethod,缩写FDBPM)和平面波展开法(plane-weexpansionmethod,缩写PWEM)计算了不同结构下基模有效折射率和包层有效折射率,应用阶跃折射率光纤模色散方程求解出塑料光子晶体光纤相应结构的等效芯半径,由此找出等效芯半径与结构参数的关系由于石英光子晶体光纤与塑料光子晶体光纤在材料折射率上差别不大,因而该结果也同样适用于石英光子晶体光纤.

应用FDBPM方法,通过对纵向场点作Fourier变换得到导模的传播常数,该方法与采用相关函数法得到的结果具有同样的精度,而实现起来更加简洁本文的结果使得有效折射率法可以按照光子晶体光纤的结构来设置其等效芯半径,在发挥其快捷高效优点的同时,使分析变得更加精确等效芯半径本身也是表征光子晶体光纤特性的一个参数,对其变化趋势的研究有助于人们进一步深入理解光子晶体光纤的传输特性.

摘自:《光子学报》2005年01期

可见光波段一维光子晶体窄频带锐角度缺陷模

关键词:光子晶体,异质结,缺陷模,全角高反带,光学滤波器,光学薄膜,光通信,抗干扰

近年许多崭新的新型光子器件相继问世.在一维光子晶体中引入缺陷,将在禁带中产生缺陷模.引入缺陷的光子晶体也可看作F-P腔,可作全介质窄带滤光片,它是在有限的周期结构中引入缺陷层而构成的.缺陷模峰值的频率会因缺陷层的折射率和厚度的改变而发生变化.对一般的含缺陷一维光子晶体,其缺陷透射峰在各种入射角都存在,而缺陷模频率随着入射角增大而紫移.我们通过耦合两个掺杂的一维光子晶体,使缺陷透射峰频率不再是所有入射角都存在,得到单一窄频带和单一锐透射角的奇特的缺陷模.此新的一维光子晶体兼具频率和空间光学滤波双性能,即在一个宽的频带范围内,该结构只允许法向入射的一确定中心频率的窄带光透过,偏离法向时具有一个宽的全反射带(包括中心频率在带偏离法向时全部反射)11.此结构设计时所用介质的折射率大于3,只能在光纤通信波段实现,它不能满足许多可见光波段和日常常用(如大气和太空光通信及激光制导等)的短于1μm的近红外波段的应用需求.本文以短于1μm波段透明的最高折射率小于2.6的材料为基础,设计了能满足这波段的应用需求的窄频带锐角度缺陷模的一维光子晶体.

可见区和近红外区透明的光学材料的折射率较低,导致宽的全角反射带等特殊结构设计和制作难度大.为获得单一角度出射的窄频带缺陷模.本文在双微腔耦合的异质结基础上,加上低频反射补偿周期结构构成三异质结,此三异质结能够实现宽的全角高反带,同时使双微腔耦合形成的窄频率锐角度的透射峰不受影响,从而实现在0°到90°范围内只有某特定的窄频带在特定角度范围内才能透射.

本文将两个不同缺陷层的微腔结构组合的双微腔异质结与一低频周期结构组成三异质结,克服了短于1μm波段因透明材料的高低折射率差值较小的限制.使同时具有空间和频率滤波功能的单一光子晶体器件从过去的长于1μm波段扩展到在短于1μm波段能实现,即空间和频率双功能的薄膜光子晶体滤波器的滤波频段从大于微米的波段扩展到可见光,近紫外和整个近红外光频段,为该器件的实际应用提供了更加广阔的空间.比起已有的空间和频率滤光的方法,该光子晶体结构具有角度滤光性能突出,体积小,重量轻,有利于集成等优点.

摘自:《激光杂志》2005年01期

用阶跃有效折射率模型研究光子晶体光纤色散特性

关键词:折射率引导型光子晶体光纤,阶跃有效折射率模型,色散

本文在采用阶跃有效折射率模型研究光子晶体光纤的可行性方面,提出了将普通单模光纤,色散位移光纤,色散平坦光纤作为一定极限条件下的折射率引导型光子晶体光纤特例的观点.通过编程计算,并与文献报道的实验数据对比,表明应用本模型可以揭示光子晶体光纤所具有的奇异的色散机理.特别是应用本模型具有更快的计算速度.还用本模型分析了空气孔直径,周期及芯径对色散特性的影响.

主要得出以下结论:

1.与常规阶跃折射率光纤相比,光子晶体光纤是一种更接近理想阶跃折射率模型的光纤,理论值与实测数据应该具有更好的一致性.理论值更具指导意义.

2.采用阶跃有效折射率模型,进行光子晶体光纤色散特性分析,需要解决的主要问题是得到如塞尔梅耶多项式一样的空气孔周期材料的色散特性表达式.采用本模型和文献报道的有效折射率公式与实验数据的对比,得到了较好的一致行和自洽性.

3.具有色散位移和色散平坦特性的W型,三包层,多包层折射率分布的光纤,是光子晶体光纤的一种简约模式,分析表明:它是折射率引导型光子晶体光纤的一种特例,阶跃有效折射率模型同样可以适用.理想阶跃折射率光纤也可以看作是折射率引导型光子晶体光纤的一种特例.

摘自:《物理学报》2005年03期

Searchfor:Keywords等于(catalyticmaterials){DATE>,等于20050101}

Title等于(catalyticmaterialst){DATE>,等于20050101}

Keywords等于(nano-structure)orKeywords等于(nanoparticles){DATE>,等于20050101}

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Result:NumericalStudyoftheImplicationsofSizeNonuniformitiesinthePerformanceofPhotonicCrystalCouplersUsingCoupledModeTheory.

Keywords:couplers,photoniccrystaltoleranceanalysis,welengthdivisionmultiplexing(WDM).

Abstract:Photoniccrystals(PCs)areapromisingtechnologyfortherealizationofhigh-densityopticalintegratedcircuits.PC-basedcouplershebeenproposedasapactmeansofachievingwelengthmultiplexinganddemultiplexing.However,theperformanceofsuchdevicescanbelimitedbyfabricationim-perfectionssuchasrodsizenonuniformities.Inthispaper,coupledmodetheory(CMT)isappliedinordertostudytheimplicationofthevariationofthesizeoftherods.CMTcanprovideausefulinsightintheeffectofsizevariations,andunlikeothernumericalmethodssuchasthefinitedifferencetimedomain,itdoesnotrequireexcessiveputationaltime.UsingCMT,therelationbetweenthesizenonuniformitiesandthecoupler'sinsertionlossandextinctionratioisanalyzed.Itisshownthatevenaallsizevariationoftheorderof2%-3%candegradetheperformanceofthedevice.

Source:IEEEJournalofQuantumElectronics,Jun2005,Vol.41Issue6

ModelingofWeResonancesinLow-ContrastPhotonicCrystals.

Keywords:photoniccrystals,coupled-modeequations,weresonancesstationarytranissionboundary-valueproblems

Abstract:Coupled-modeequationsarederivedfromMaxwellequationormodelingoflow-contrastcubic-latticephotoniccrystalsinthreespatialdimensions.Coupled-modeequationsdescriberesonantlyinteractingBlochwesinstopbandsofthephotoniccrystal.Westudythelinearboundary-valueproblemforstationarytranissionoffourcounter-propagatingandtwoobliquewesontheplane.Well-posednessoftheboundary-valueproblemisprovedbyusingthemethodofseparationofvariablesandgeneralizedFourierseries.Forapplicationsinphotonicoptics,weputeintegralinvariantortranission,reflection,anddiffractionofresonantwes.

Source:SIAMJournalonAppliedMathematics,2005,Vol.65Issue4

FabricationofSinano-pillararraythroughNinano-dotmaskusinginductivelycoupledplaa.

Keywords:Sinano-pillar,Ninano-dot,Photoniccrystal

Abstract:WeformedSinano-pillararrayusinginductivelycoupledplaa(ICP)etchingofSiwithNinano-dotmask.FortheformationofNinano-dotmask,NiwasdepositedonSisubstrateusingsputtering.Throughrapidthermalannealing(RTA)ofNilayerat700°C,Ninano-dotarraywaormedonSisubstrate.Effectsofetchingparameterssuchasrfpower,biasvoltageandgaspositiononthemorphologiesofSinano-pillararraywereinvestigated.OptimumetchingofSiwithNinano-dotmaskwasobtainedunderthebiasvoltageof90V,powerof1500WandgaspositionofCF<,sub>,4<,/sub>,(70%)andsulfurhexafluoride(<,sub>,6<,/sub>,,30%).Sinano-pillararraywithadiameterallerthan50nmandaspectratiolargerthan10waormed.

Source:ThinSolidFilms,Mar2005,Vol.475Issue1/2

sisofthedesignofanewtunablephotoniccrystalfilteratvisibleband.

Keywords:Photoniccrystals,Defectmodes

Abstract:Anewtunablephotoniccrystalfilteratvisiblebandhasbeenproposedanddesigned,dependingonthecharacteristicsofthedefectmodesofphotoniccrystalsindifferentconditions.Modifyinggraduallytheparametersofthelatticestructureina2Dphotoniccrystalwithasquarestructureprovidesagoodopticaltuningmethodonewithanalterabledynamicrangeandanarrowbandwidthof0.34nmatvisiblebandhasbeenobtained.

Source:PhysicaE,Mar2005,Vol.27Issue1/2

HighpowerQ-switchedYb-dopedphotoniccrystalfiberlaserproducingsub-10nspulses

Keywords:42.55.Wd(Fiberlasers),42.60.G(Q-switching)

Abstract:WereportonaQ-switchedfiberlaserproducingpulsedurationswellbelow10nsbyusingashort-lengthytterbium-dopedrod-typephotoniccrystalfiberasgainmedium.Atrepetitionratesupto100kHzpulseenergiesupto0.5mJanderagepowersinexcessof30Whebeenobtainedinsingle-transversemodebeamquality.Thepactshortpulselasersystempossesseurtherpowerandenergyscalingpotential.

Source:JournalofRussianLaserResearchVolume81,Number1July2005

RamanScatteringinThree-DimensionalPhotonicCrystals

Keywords:Ramanscattering,nanocityscattering,globularphotoniccrystal,opal,nanoglobules,nanoclusters

Abstract:Theopticalpropertiesofthree-dimensionalphotoniccrystalsassociatedwiththeformofreflectionspectrafromtheirsurface(appearanceofaforbiddengapintheenergyspectrum)andwiththespecificfeaturesofRamanscatteringareanalyzed.Idealizedmodelsoftheenergybandstructureofphotoniccrystalsarestudied.Expressionorthegroupvelocityofphotonswithenergyclosetotheforbiddengaparederived.ExperimentalresultsontheRamanscatteringinphotoniccrystalsbasedonartificialopalaswellasinfusedsilicaarediscussed.Bandsduetoquantum-sizeeffects(presenceofnanoclustersinfusedsilicaandnanoglobuleormingthelatticeofglobularphotoniccrystals)weremanifestedinthespectraofinelasticlightscattering.ItisproposedtousephotoniccrystalorthecreationofsensitivesensorsofanicandinanicsubstancesusingmodernRamantechniques.

Source:JournalofRussianLaserResearchVolume26,Number3May2005

Numericalcharacterizationofnanopillarphotoniccrystalweguidesanddirectionalcouplers

Keywords:directionalcouplers,nanoscalephotonics,photoniccrystalweguides,tranission

Abstract:Wenumericallycharacterizeanoveltypeofaphotoniccrystalweguide,whichconsistsofseveralrowsofperiodicallyarrangeddielectriccylinders.Insuchananopillarphotoniccrystalweguide,lightconfinementisduetothetotalinternalreflection.Ananopillarweguideisamultimodeweguide,wherethenumberofmodesisequaltothenumberofrowsbuildingtheweguide.Thestrongcouplingbetweenindividualweguidesleadstotheproposalofanultrashortdirectionalcouplerbasedonnanopillarweguides.Wepresentasystematicanalysisofthedispersionandtranissionefficiencyofnanopillarphotoniccrystalweguidesanddirectionalcouplers.Planeweexpansionandfinitedifferencetimedomainmethodswereusedtocharacterizenumericallynanopillarphotoniccrystalstructuresbothintwo-andthree-dimensionalspaces.

Source:OpticalandQuantumElectronicsVolume37,Numbers1-3January2005

Blochwepropagationintwo-dimensionalphotoniccrystals:Influenceofthepolarization

Keywords:photoniccrystal,Blochwe,,Fourieranalysis,left-handedmaterials

Abstract:TransverseMagic(TM)andTransverseElectric(TE)opticalBlochwesarethegenericsolutionsofMaxwell'sequationsintwo-dimensionalphotoniccrystals(2D-PhCs).WepresentanintuitivedescriptionofthesewesbasedontheirFourierdepositionintoseriesofelectromagicwes.ThepropertiesoftheseelectromagicwesaswellastheircontributiontotheglobalenergyandgroupvelocityoftheglobalBlochwearediscussedforeachpolarization.Thisdescriptionprovidesasimpleandintuitivemethodtounderstanddispersionandgroupvelocityeffectsin2D-PhCs.

Source:OpticalandQuantumElectronicsVolume37,Numbers1-3January2005

Photoniccrystalfiberswithmaterialanisotropy

Keywords:birefringence,electromagicmodeling,photoniccrystalfibers

Abstract:Inthispaperwearemodelingtheinterplayofmaterialandformbirefringenceinphotoniccrystalfibers.Weintroduceanefficientnumericalmethodforthecalculationofthemodalstructure.Ourapproachreliessolvingthefullyvectorialweequationforthetransversemagicfieldandtherespectivepropagationconstantsusingaplaneweexpansion.Themethodaccountorasimpleformofmaterialanisotropy.Ouranalysisisrelevanttocertainapplicationareas,andinparticulartofibersensing,wherematerialbirefringenceariseorinstanceduetotransversallyappliedmechanicalstress.Weanalyzetheinfluenceofmaterialbirefringenceonthemodalbirefringenceandthestateofpolarizationofthefundamentalmode.

Source:OpticalandQuantumElectronicsIssue:Volume37,Numbers1-3January2005

Bandstructuresinnonlinearphotoniccrystalslabs

Keywords:finite-differencetime-domainmethod,Kerr-nonlinearmaterial,

photoniccrystalslab,red-shift

Abstract:Thefinite-differencetime-domainmethodwasusedtoanalyzebandstructuresintwo-dimensionalKerr-nonlinearphotoniccrystalslabs.Atriangularlatticeofcircularairrodswasconsidered.Resultsshowred-shiftingofthebandstructureduetothenonlinearityandtheincidentintensity.Thered-shiftofthebandgapbetweenthefirstandthesecondbandsiaximalwhentheairrodradiusisintherange0.2ato0.25a,whereaistheperiod.

Source:OpticalandQuantumElectronicsIssue:Volume37,Numbers1-3January2005

SurfaceOstwald-ripeningandevaporationofgoldbeadedfilmsonsapphire

Keywords:Ostwald-ripening,beadedfilms,catalysts

Abstract:Thekiicsofmorphologicalevolutionsofgoldnanoparticlesonalumina,resultingfromevaporationandsurfaceOstwald-ripeningcoarsening,hebeeninvestigatedbymeansofAugerelectronspectroscopy.Whenthefractionofthecoveredareaisall,thekiicsofevaporationcanberelatedtothedesorptionofadatoms.Inthetemperaturerange943–1043KweobtainedtheevaporationfluxJ(m-2s-1)等于4.8×1027exp[-196±9(kJ/mol)/RT].Theexperimentalactivationenergyofevaporationofgoldfromasapphiresurface,Qevap等于196±9kJ/mol,islowerthanthetabulatedvalueofenthalpyofsublimationofgold,Hsubl等于368kJ/mol.Atlowertemperatures,intherange623–778K,Ostwald-ripeningexperiments,carriedoutonnanosizedclusters,yieldthemasstranersurfacediffusioncoefficientsofgoldonalumina,Ds(m2/s)等于2.6×10–14exp[-58±9(kJ/mol)/RT].Theseresults,providinginformationontheevolutionofgranulargoldfilmssuchasthoseusedincatalystsorsensors,areparedtopreviousdataonsimilarsystems.

Source:AppliedPhysicsA:MaterialsScience&,Processing

Volume81,Number4September2005

AdhesionandproliferationofOCT-1osteoblast-likecellsonmicro-andnano-scaletopographystructuredpoly(l-lactide).

Keywords:Polystyrene,Celladhesion,Osteoblast,Nano-scale,Poly(l-lactide)

Abstract:Theimpactofthesurfacetopographyofpolylactone-typepolymeroncelladhesionwastobeconcernedbecausethemicro-scaletextureofasurfacecanprovideasignificanteffectontheadhesionbehiorofcellsonthesurface.Especiallyfortheapplicationoftissueengineeringscaffold,theporesizecouldheaninfluenceoncellin-growthandsubsequentproliferation.Micro-fabricationtechnologywasusedtogeneratespecifictopographytoinvestigatetherelationshipbetweenthecellsandsurface.Inthisstudythepits-patternedsurfacesofpolystyrene(PS)filmwithdiameters2.2and0.45μmwerepreparedbyphase-separation,andthecorrespondingscaleislands-patternedPLLAsurfacewaspreparedbyamoldingtechniqueusingthepits-patternedPSasatemplate.TheadhesionandproliferationbehiorofOCT-1osteoblast-likecellorphologyonthepits-andislands-patternedsurfacewerecharacterizedbySEMobservation,cellattachmentefficiencymeasurementandMTTassay.TheresultsshowedthatthecelladhesioncouldbeenhancedonPLLAandPSsurfacewithnano-scaleandmicro-scaleroughnessparedtotheoothsurfacesofthePLLAandPS.TheOCT-1osteoblast-likecellscouldgrowalongthesurfacewithtwodifferentsizeislandsofPLLAandgrowinsidethemicro-scalepitsofthePS.However,theproliferationofcellsonthemicro-andnano-scalepatternedsurfacehasnotbeenenhancedparedwiththecontrolledoothsurface.

Source:Biomaterials,Jul2005,Vol.26Issue21

Guidedboneregenerationmembranemadeofpolycaprolactone/calciumcarbonatepositenano-fibers

Keywords:Calciumcarbonate,Celladhesion,Nano-posite

Abstract:Inthisstudy,newtypeofguidedboneregeneration(GBR)membraneswerefabricatedbypolycaprolactone(PCL)/CaCOositenano-fiberswithtwodifferentPCLtocalciumcarbonate(CaCO3)ratios(PCL:CaCO3等于75:25wt%and25:75wt%).Thepositenano-fibersweresuccesullyfabricatedbyelectrospinningmethodandCaCO3nano-particlesonthesurfaceofnano-fiberswereconfirmedbyenergydisperseX-ray(EDX)analysis.InordertoachievemechanicalstabilityofGBRmembranes,positenano-fiberswerespunonPCLnano-fibrouembraneswhichhashightensilestrength,i.e.,themembranesconsistoftwolayersoffunctionallayer(PCL/CaCO3)andmechanicalsupportlayer(PCL).TwodifferentGBRmembraneswereprepared,i.e.,GBRmembrane(A)等于PCL:CaCO3等于75:25wt%+PCL,GBRmembrane(B)等于PCL:CaCO3等于25:75wt%+PCL.OsteoblastattachmentandproliferationofGBRmembrane(A)and(B)werediscussedbyMTSassayandscanningelectronmicroscope(SEM)observation.Asaresult,absorbanceintensityofGBRmembrane(A)andtissueculturepolystyrene(TCPS)increasedduring5daysseedingtime.Incontrast,althoughabsorbanceintensityofGBRmembrane(B)alsoincreased,itsvaluewaslowerthanmembrane(A).SEMobservationshowedthatnosignificantdifferenceinosteoblastattachmentmannerwasseenonGBRmembrane(A)and(B).Becauseofgoodcellattachmentmanner,thereisapotentialtoutilizePCL/CaCOositenano-fiberstoGBRmembranes.

Source:Biomaterials,Jul2005,Vol.26Issue19

Processingandshapeeffectsonsilverpasteelectricallyconductiveadhesives(ECAs).

Keywords:ELECTRICALLYCONDUCTIVEADHESIVES,NANO-SIZEDSILVERPOWDER,SILVERCONDUCTIVEFILLER

Abstract:Variousamountsofsilverflakesanddendriteswereusedasconductivefillersinanelectricallyconductiveadhesive(ECA)resinwithDPM,BCAandxyleneasdiluenttohelpuniformdistributionoffillerparticlesinthematrix.Duetothefactthatthehigherthetemperature,thehighertheshrinkagerateofthepolymerresinand,consequently,thelargertheconnectingareain-betweenfillers,abettercuringconditionforprocessingsilverfilledECAwaoundtobearelativelyhighercuringtemperature.Themechaniofconductivityachievementinconductiveadhesiveswasanalyzedbyparingprocessingconditions,resistivityandmicrostructures.Inaddition,theinfluenceofaddingnano-sizedsilverparticlesontheresistivityoftheconductiveadhesiveswasalsoinvestigatedandtheadditionofnano-sizedsilverparticlesresultedinalowerpercolationthresholdforECAs.

Source:JournalofAdhesionScience&,Technology,2005,Vol.19Issue7

CriticalCurrentDensityofHTSSingleCrystalYBCOThinFilmsinApplieddcField.

Keywords:crystaldefects,nano-structure,thinfilms,vortexpinning,Y-Ba-Cu-Osuperconductor,Criticalcurrent

Abstract:MagicfieldandangledependenciesofcriticalcurrentdensityJ<,sub>,C<,/sub>,(H,θ)aremeasuredforsingle-crystalc-orientedepitaxialYba<,sub>,2<,/sub>,Cu<,sub>,3<,/sub>,O<,sub>,7-δ<,/sub>,thinfilmswithhighJ<,sub>,c<,/sub>,≈2MA/cm2at77K.Filmsaredepositedbyoff-axisdcmagronsputteringontor-cutsapphiresubstratesbufferedwithCeO<,sub>,2<,/sub>Experimentalevidencesofthedominantcontributionofextendedlineardefects(growth-inducedout-of-planeedgedislocations)topinningmechaniandcriticalcurrentbehiorarepresented.Aconsistentmodelofvortexlatticedepinningfromalineardefectsystemisdeveloped.DetailedJ<,sub>,c<,/sub>,(H)measurementsstartfromverylowfields(<,0.001T).QualitativelydifferentangledependenciesJ<,sub>,c<,/sub>,(θ)areobtainedindifferentfieldranges.Theirevolutionisprehendedonthebaseofdepinningmodel.The"peak-effect"observedinJ<,sub>,c<,/sub>,(H)-dependenciesatparallelmagicfieldisdiscussedasacontributionofelectromagicpinning.

Source:IEEETransactionsonAppliedSuperconductivity,Jun2005Part3of3,Vol.15Issue2

MicrostructuresandEnhancementofCriticalCurrentDensityinYBa<,sub>,2<,/sub>,Cu<,sub>,3<,/sub>,O<,sub>,7<,/sub>,ThinFilmsGrownbyPulsedLaserDepositiononVariousSingleCrystalSubstratesModifiedbyAgNano-Dots.

Keywords:laserdeposition,microstructures,nano-doping,substrate,superconductingfilms,Criticalcurrentdensity

Abstract:YBa<,sub>,2<,/sub>,Cu<,sub>,3<,/sub>,O<,sub>,7<,/sub>,(Y123)thinfilmsweregrownbypulsedlaserdeposition(PLD)onYSZ(100),SrTiO<,sub>,3<,/sub>,(100),andLaAlO<,sub>,3<,/sub>,(100)singlecrystalsubstrates.Priortothefilmdeposition,adiscontinuouslayerofAgnano-dotswasdepositedonthesubstrates.TheY123filmsgrownonsuchsurfaceodifiedwithAgnano-dotswerecharacterizedbyAtomicForceMicroscopy(AFM),X-raydiffraction(XRD),scanningelectronmicroscopy(SEM),ACsusceptibilityandDCmagization.TheeffectsofthedensityofAgnano-dots,whichwascontrolledbythenumbersofPLDshots,onthemicrostructuresandresultantcriticalcurrentdensityJ<,sub>,c<,/sub>,hebeenstudiedsystematically.ResultsshowedthatatfixedphysicaldepositionconditionsJ<,sub>,c<,/sub>,increasedmonotonicallywithnumberofAgshots,n,forfilmsgrownonbothSTOandLAOsubstrates.At77K,theJ<,sub>,c<,/sub>,increasedfrom10<,sup>,6<,/sup>,to3.2×10°A/cm2forLAOandfrom8×10<,sup>,5<,/sup>,to3.5×10<,sup>,6<,/sup>,A/cm2forSTOasnincreasedfrom0to150.At5K,theenhancementofJ<,sub>,c<,/sub>,wasapproximatelyfourtimesatbothlowandhighfields.However,forfilmsgrownonYSZsubstrate,J<,sub>,c<,/sub>,increasedfrom2×10<,sup>,5<,/sup>,to2×10<,sup>,6<,/sup>,A/cm2asAgshotsincreasedfrom0to30,anddecreasedto9×10<,sup>,5<,/sup>,forn≥60.DetailedmicrostructureinvestigationsindicatedthatthecrystallinityandabalignmentgraduallyimprovedasthenumberofAg-nano-dotsincreased.

Source:IEEETransactionsonAppliedSuperconductivity,Jun2005Part3of3,Vol.15Issue2

Measuringmercuryionconcentrationwithacarbonnanotubepasteelectrodeusingthecyclicvoltammetrymethod.

Keywords:carbonnanotube,mercuryion,pasteelectrode,voltammetry

Source:Asimplypreparedcarbonnanotubepasteelectrode(CNTPE)wasutilizedformonitoringmercuryionconcentrationusingthecyclicvoltammetry(CV)methodandthesquareweanodicstrippinoltammetric(SWASV)method.TheCNTPEwasparedwithvariousconventionalelectrodes.TheCNTPEmethodwasappliedtodeterminetheconcentrationoftracelevelsofHg(II)inseveralwatersamples,whichyieldedarelativeerrorof0.6%withaconcentrationof0.20mgL<,sup>,-1<,/sup>,Hg(II).Itwasdepositedat-0.5V(vsAg/AgCl),whichwassubsequentlyreducedto+0.20VtostripitontheCNTPE.Theoptimalexperimentalconditionortheanalysiswerefoundtobeaollows:pHvalueof4forthemedium,depositionpotentialof-0.5V,depositiontimeof210s,SWfrequencyof40Hz,SWamplitudeof100mV,andsteppotentialof25mV.Giventheseoptimumconditions,alinearrangewasobservedwithintheconcentrationsof1.0-25.0μgL<,sup>,-1<,/sup>,and40.0-200.0μgL<,sup>,-1<,/sup>Thedetectionlimitwaoundtobe0.42μgL<,sup>,-1<,/sup>

Source:JournalofAppliedElectrochemistry,Jun2005,Vol.35Issue6

Synthesisandphotocatalyticpropertiesofnanobi-crystallinetitaniaofanataseandbrookitebyhydrolyzingTiOCl<,sub>,2<,/sub>,aqueoussolutionatlowtemperatures.

Keywords:NANOANATASE,BROOKITETITANIA,X-RAYDIFFRACTION,brookitetitania,X-raydiffraction.,Nanoanatase

Abstract:Well-dispersednano-anataseorbi-crystalline(anatase+brookite)titaniapowderswithaeragecrystalsizebelow10nmhebeenpreparedfromaqueousTiOCl<,sub>,2<,/sub>,solutionbyadjustingpHvaluesofstartingsolutionandaddingdifferentadditivesatlowtemperatures.Amorphous–anatasetranormationoftitaniacouldproceedinaliquid–solidreactionatlowtemperatures,evenaroundroomtemperature,bycatalyticsupportofH<,sup>,+<,/sup>,ion.ThepresenceofaallamountofSO<,sup>,2-<,/sup>,<,sub>,4<,/sub>,ionisalsounforabletotheformationofbothrutileandbrookite.Bycarefullyadjustingpreparationconditions,nanopureanatasewithhighersurfacearea,goodcrystallinityanderygoodphotocatalyticactivityforgas-phaseoxidationofbenzenewasobtained.

Source:ResearchonChemicalIntermediates,2005,Vol.31Issue4,

Comparisonofnano-indentationhardnesstomicrohardness.

Keywords:Nano-indentationhardness,Materialmechanicalproperty,Hardness,Indentation

Abstract:Withanano-indenterandamicrohardnesstestingmachine,nano-indentationhardnessandmicrohardnessaremeasuredinawideloadrange(0.1–19600mN)forfivematerials.Evenfusedsilicaandsiliconalmostheconstanthardnessduringtheloadrange,thenano-indentationhardnessofcopper,stainlesssteelandnickeltitaniumalloyshowsobviousindentationsizeeffect,namelythatthehardnessdecreaseswiththeincreaseofdepth.Forthemeasuredmaterials,thenano-indentationhardnessisabout10–30%inmagnitudelargerthanthemicrohardness.Themainreasonscanbeexplainedastheanalysisofthenano-indentationhardnessusingtheprojectedcontactareaatpeakloadA<,sub>,c<,/sub>,insteadoftheresidualprojectedareaA<,sub>,r<,/sub>,,aswellasthepurelyelasticcontactassumptiondescribingtheelastic/plasticindentationprocess.TheanalysisbasedonasimplemodelindicatesthatA<,sub>,c<,/sub>,isalwaysallerthanA<,sub>,r<,/sub>,,andthemoreheilytheindentpilesup(orsinksin),thelargerthedifferencebetweenthenano-indentationhardnessandmicrohardness.

Source:Surface&,CoatingsTechnology,May2005,Vol.195Issue2/3

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