Analysis and optimal design of layered composites with high stiffness and high damping
ElectrospunPLAPCLFiberswithTubularNanoclay
Electrospun PLA/PCL Fibers with Tubular Nanoclay: Morphological and Structural AnalysisHazim J.Haroosh,1Deeptangshu S.Chaudhary,1Yu Dong21Department of Chemical Engineering,Curtin University,Perth,WA6845,Australia2Department of Mechanical Engineering,Curtin University,Perth,WA6845,AustraliaReceived17March2011;accepted9August2011DOI10.1002/app.35448Published online28November2011in Wiley Online Library().ABSTRACT:Biodegradable polymers are good candi-dates for a wide range of applications in tissue engineering and drug delivery because of their biocompatibility,their degradation,mechanical properties,and offer a sustained release of encapsulated drugs.The electrospun polymer nanofibrous materials can be used as carriers for hydro-phobic and hydrophilic drugs.This research work focused on poly(lactic acid)(PLA)and blends of PLA with poly (e-caprolactone)(PCL)that are reinforced with different concentrations of halloysite nanotubes(HNTs)and various cosolvents for electrospinning including chloroform:ace-tone,chloroform:methanol,and dichloromethane(DCM): N,N,dimethylformamide(DFM).The fibers produced from the DCM:DMF system without HNTs were more uniform resulting in smaller fiber diameters as compared to the chloroform:methanol system due to the increased solution conductivity.The addition of HNT nanoparticles produced electrospun fibers with large diameters because the viscos-ity of the solution increased.Cosolvent was important in determining fiber diameters because it strongly influenced the solution viscosity and conductivity.HNTs had rela-tively small impact on the growth of a crystalline morphol-ogy in PCL–HNT composites.The solvent mixture of chloroform:methanol was better for PLA-based systems since PLA was found to have slightly higher crystallinity and larger enthalpy value indicating the improved struc-tural orderness in the PLA polymer matrix.V C2011Wiley Periodicals,Inc.J Appl Polym Sci124:3930–3939,2012Key words:electrospinning;nanocomposites;poly(lactic acid);poly(e-caprolactone);X-ray diffraction;differential scanning calorimetryINTRODUCTION Electrospinning is a multipurpose polymer process-ing technique in which a stream of a melt or poly-mer solution is connected to a high electric field, resulting in formation of nanoscaled fibers.It offers a promising way to fabricate continuous fibers with diameters ranging from nano-to microscaled level.1 The electrospun nonwoven fabrics consisting of ultrafine fibers were found to have wide applica-tions such as separation filters,carbonaceous materi-als,1and scaffolding for tissue engineering in bio-medical fields,tissue repair substitutes,and carriers for drug delivery platform due to their high specific surface area and porous structure.2Polymers have been commonly used in several applications in the pharmaceutical industry as car-rier for tissue engineering and drug delivery.Till now,electrospinning has been used for the fabrica-tion of a numerous biodegradable polymers for drug delivery,such as poly(lactic acid)(PLA),poly (e-caprolactone)(PCL),poly(glycolic acid)(PGA), poly(lactide-co-glycolide)(PLGA),and polyurethane (PU)as well as natural proteins including collagen, gelatin,and elastin.3High molecular weight poly(lactide)(PLA)pro-vides better mechanical strength and integrity to the scaffold4and thus are promising for clinical uses because the acidic environment induced by the deg-radation of the polymer helps to reduce the bacteria growth and promote epithelization.This is mainly due to their biocompatibility and the flexibility they offer in terms of their degradation profiles and mechanical properties.2Additionally,Poly(e-capro-lactone)(PCL)is well known for its slow biodegrad-ability,high biocompatibility,and good drug permeability.5,6Halloysite nanotubes(HNT)are clays belonging to the kaolinite family.HNT is in tubular shape with lengths in the range of1–3l m and diam-eters in size of100–300nm.It has been recently reported that owing to the hydroxides groups in the HNT structure,the incorporation of HNT within PLA polymer can resist the negative effect of PLA acidic environment.7In addition,many solvents exist for successful electrospinning,and therefore it is essential to choose an appropriate solvent system that should be able to improve solution parameters and allow polymers to spin with good properties.8–10Correspondence to:D.S.Chaudhary(d.chaudhary@curtin. edu.au).Journal of Applied Polymer Science,Vol.124,3930–3939(2012) V C2011Wiley Periodicals,Inc.The focus on this study is to understand the effect of the cosolvents and the addition of HNT nanopar-ticles in PCL/PLA blend system.Because PCL is widely used as long-term implantable devices,blend-ing with PLA and HNT can deliver a new drug delivery system with sustained release property for a range of applications in tissue engineering and drug delivery.For this reason,this study will investigate the electrospun fiber diameters of biopolymer blend of high molecular weight of PLA with low molecular weight of PCL.EXPERIMENTALMaterialsPoly (e -caprolactone)PCL (M n ¼33,000g mol À1)was purchased from Daicel Chemical Industries,Japan,poly lactide acid (PLA)3051D,M n ¼93,500g mol À1,T g ¼65.50 C 11was supplied by NatureWorks USA,and halloysite nanotubes (HNT)from Imerys tableware Limited,New Zealand,while dichlorome-thane (DCM),dimethylformamide (DMF),chloro-form,and methanol were purchased from Sigma-Aldrich,used without any purification.ElectrospinningElectrospinning was carried out using 8%wt/v PLA solution mixed with 15%wt/v PCL at different ratios of 1:0,3:1,and 1:1with three solvents,namely DCM :DMF at 3:1,chloroform :methanol at 2:1and chloroform :acetone at 2:1.The HNT suspension was added at 1%wt/v and 2%wt/v to the polymer solution for all solvents and was homogenized for 30min under ultrasonication.For electrospinning process,the solutions were trans-ferred to a 10-mL syringe pump with 20-G needles.The flow rate of polymer solution was 2mL h À1,and the applied positive voltage was in the range of25–28kV.The resulting fibers were collected on a flat aluminum foil.The distance between the needle tip and the target was 13–15cm.The thickness of the fiber mat ranged from 300to 450l m.Viscosity of solutionsThe viscosity of solution was measured by using Visco 88—a portable viscometer from Malvern instruments (UK),with built-in temperature sensor,and supplied with a double gap measuring geometry to provide extra sensitivities when measuring low viscosity fluids.Scanning electron microscopic (SEM)studies The morphology of electrospun nanofibers was stud-ied by an EVO 40XVP scanning electronmicroscopeFigure 1SEM micrographs of electrospun PLA :PCL fibers by using DCM :DMF as a solvent and containing various PLA :PCL blend ratios by weight (a)1:0,(b)3:1,and (c)1:1.The scale bar in the micrograph is 10lm.Figure 2Viscosity of different percentages of PLA :PCL solutions dissolved in the mixture of DCM :DMF,chloro-form :methanol,and chloroform :acetone.[Color figure can be viewed in the online issue,which is available at .]ELECTROSPUN PLA/PCL FIBERS WITH TUBULAR NANOCLAY 3931Journal of Applied Polymer Science DOI 10.1002/app(Germany)and the accelerating voltage was set at 5kV.Before SEM observation,the samples were sput-ter-coated with platinum.Fiber diameter was calcu-lated from the SEM images by using an in-house developed scanning program,which analyzes a min-imum of 50fibers from a scanned SEM image,and includes a statistical deviation of 15%.X-ray diffraction (XRD)A total of 11samples were chosen from the complete set of electrospun fiber samples to investigate the crystallinity and thermal properties which would highlight the interaction between the nanoclay and the polymer matrix.These samples were identified based on a Design of Experiment (DoE)analysis using commercial statistical software,MINITABLLC,version 3.2.XRD measurements of the pre-pared samples were performed in a Bruker Discover 8diffractometer (Germany)operating at 40kV and 40mA using Cu K a radiation that was monochrom-atized with a graphite sample monochromator with a 2y range from 5 to 30 at a scanning rate of 0.05 s À1.The basal spacing of the silicate layered was determined from the Bragg’s equation,k ¼2d sin y (where y is the diffraction position and k is the wavelength).Igor software package (Wavemetrics,Lake Oswego,Oregon)was used for curve posite crystallinity was calculated based on a peak fitting procedure.The fitted coefficients were calculated based on minimized values of Chi-square using the Levenberg–Marquardt algorithm.Each fit-ting procedure was repeated eight times with differ-ent initial inputs to ensure the data reproducibility.Differential scanning calorimetry (DSC)DSC was performed using a DSC6000Perkin Elmer (USA)with Cryofill liquid nitrogen cooling system.Approximately 10mg of fibers were sealed in alumi-num pans and their thermal behavior wasanalyzedFigure 3SEM micrographs of electrospun PLA :PCL fibers by using chloroform :methanol as a solvent and containing various PLA :PCL blend ratios by weight (a)1:0,(b)3:1,and (c)1:1.The scale in the micrograph is 10l m.TABLE IDielectric Constant for SolventsDMFMethanolAcetone DCM ChloroformDielectric constant38.333219.14.8Figure 4SEM micrographs of electrospun PLA :PCL fibers by using chloroform :acetone as a solvent and containing various PLA :PCL blend ratios by weight (a)1:0,(b)3:1,and (c)1:1.The scale in the micrograph is 10l m.3932HAROOSH,CHAUDHARY,AND DONGJournal of Applied Polymer Science DOI 10.1002/appduring heating and cooling between30and180 C with a ramp rate of10 C minÀ1.RESULTS AND DISCUSSIONSWithout HNT loadingFigure1(a)shows that using PLA in DCM:DMF led to homogenous fibers with the average diameter of450nm with a large variation in fiber diameters. Increasing the amount of PCL to PLA(1:3)resulted in fibers with average diameter of490nm with max-imum and minimum diameters of800and230nm, respectively.Moreover,increasing the percentage of PCL(1:1)caused beads and inhomogeneity in structures with a decrease in diameter to250nm with maximum and minimum diameters of425and 130nm,respectively as shown in Figure1(c).This indicates that by lowering the solution viscosity,the fiber diameter can be reduced,but to a great extent inhomogeneity occurs in the fiber structure,which is a possible reason for the beads to occur in the elec-trospinning process.Figure2gives the result of viscosity of different percentage of PLA:PCL solutions dissolved in the mixture of DCM:DMF,chloroform:methanol,and chloroform:acetone.It can be seen that increasing PCL amount led to the decrease of solution viscos-ities;Only33%PCL lowered the blend viscosity by more than50%,regardless of the solvent while beyond50%of PCL in the blend,the drop of solu-tion viscosity is not so significant.Figure3(a)shows that using PLA dissolved in chloroform:methanol produced fibers with the aver-age diameter of510nm and with a maximum diam-eter of740nm.Increasing the percentage of PCL to PLA(1:3)produced fibers with beads with the av-erage fiber diameter of325nm with maximum and minimum diameters of390and260nm,respectively and by increasing the percentage of PCL to(1:1) there was no fiber structure obtained.Considering that the solution viscosity is critical in forming fibers,Figure2shows that the viscosity was significantly reduced by the addition of PCL in1:1 ratio and its effect on the electrospun fibers was theTABLE IISummaries of the all Average Fiber Diameters(in nm)for all StructuresCosolventsPLA:PCL(1:0)PLA:PCL(3:1)PLA:PCL(1:1)DMF:DCM450(625)490(630)250(640)Chloroform:methanol510(625)325(640)NAChloroform:acetone570(630)375(645)NAFigure5Viscosity of different percentage of PLA:PCL solutions dissolved in the mixture of(a)DCM:DMF with HNT (b)chloroform:acetone with HNT(c)chloroform:methanol with HNT.[Color figure can be viewed in the online issue, which is available at .]ELECTROSPUN PLA/PCL FIBERS WITH TUBULAR NANOCLAY3933Journal of Applied Polymer Science DOI10.1002/appsame as seen with DCM :DMF solvent.The fibers produced from the DCM :DMF system (all percen-tages)were uniform,resulting in fibers with smaller diameters,as compared to fibers obtained from chlo-roform:methanol system and this is because the con-ductivity of DCM :DMF solution is higher than the chloroform:methanol solution.DMF has a higher dielectric constant than methanol while DCM has a higher dielectric constant than chloroform as shown on Table I.As a result,increasing the conductivity aided in the production of uniform charge density and beads-free fibers,and also higher conductivities yielded smaller fibers as shown earlier.12Figure 4(a)demonstrates that electrospun PLA dissolved in chloroform :acetone led to produced fibers with average diameter of 570nm with the maximum diameter of 775nm,while increasing the amount of PCL to PLA (1:3)produced fibers with inhomogeneity in structure and the average diame-ter reduced to 375nm with the maximum diameter of 600nm.Further increase in PCL led to no fiber formation as shown in Figure 4(c).Table II summa-ries the average fiber diameters for all structures.The significance of the solution conductivity can be gauged from Tables I and II.For all polymer blends systems,fibers diameters andstructuralFigure 6SEM micrographs of electrospun PLA :PCL fibers by using chloroform :methanol as a solvent and containing various PLA :PCL blend ratios (a1)1:0,(b1)3:1,and (c1)1:1with 1wt %of HNT and (a2)1:0,(b2)3:1,and (c2)1:1with 2wt %of HNT.The scale in the micrograph is 10l m.3934HAROOSH,CHAUDHARY,AND DONGJournal of Applied Polymer Science DOI 10.1002/apphomogeneity showed the strong correlation with sol-vent types used.Effect of HNT loadingWith the addition of nanoclays,solution viscosities tend to increase even though the overall trend was decreasing as the PCL content increased,as illus-trated in Figure 5,which is similar to resultsreported elsewhere.13Figures 6–8show that usingPLA and PLA :PCL blends at different percentages have significantly dissimilar behavior.It is evident that the addition of nanoclay always increased the fiber diameters.This is because HNT increases the electrical conductivity and the viscosity of the solu-tion.7Table III summaries the average fiber diame-ters for 1and 2wt %HNT.When compared with samples without HNT loading,Figure 6revealed that using PLA and PLA :PCL blend in chloroform :methanol with HNT produced good fibers in the 450nm range,especially for PLA :PCL (3:1).In addi-tion,the high volatility of methanol allowedforFigure 7SEM micrographs of electrospun PLA :PCL fibers by using DCM :DMF as a solvent and containing various PLA :PCL blend ratios (a1)1:0,(b1)3:1,and (c1)1:1with 1wt %of HNT and (a2)1:0,(b2)3:1,and (c2)1:1with 2wt %of HNT.The scale in the micrograph is 10l m.F6–F8ELECTROSPUN PLA/PCL FIBERS WITH TUBULAR NANOCLAY 3935Journal of Applied Polymer Science DOI 10.1002/appadequate evaporation of the solvent before the depo-sition of fibers on the collector plate,leading to the formation of the highly fibrous structure.14On the other hand,as shown in Figure 7,electro-spun PLA and PLA :PCL blend in DCM :DMF with HNT produced significantly thicker fibers as compared to samples without HNT.This occurred despite an increase in the solution conductivity.Dur-ing the electrospinning process,it was observed that the solution had some flow difficulty due to the increased viscosity of the solution,and most likely,the electric potential could not overcome the effect of the increased viscosity leading to a failure in forming a polymer jet.15Furthermore,unlike metha-nol,the low volatility of DMF led to reduced solvent evaporation leading to fibers that were wet at the collector plate.16When compared with SEM images of fibers from chloroform :acetone solution,it can be seen that fibers from chloroform:acetone (Figure 8)have the smallest diameter,but also they show a greater amount of bead formation.Hence,highconductivityFigure 8SEM micrographs of electrospun PLA :PCL fibers by using chloroform :acetone as a solvent and containing various PLA :PCL blend ratios by weight (a1)1:0,(b1)3:1,and (c1)1:1with 1of HNT and (a2)1:0,(b2)3:1,and (c2)1:1with 2wt %of HNT.The scale in the micrograph is 10l m.3936HAROOSH,CHAUDHARY,AND DONGJournal of Applied Polymer Science DOI 10.1002/appof the solution may not overcome the surface tension and increased viscosity of the solution by using a low volatile solvent.Crystallinity and thermal property analysisAs seen from the X-ray diffraction patterns(Fig.9), the electrospun samples indicated a mix of interca-lated morphologies depending upon the type of sol-vent used.Observed in Figure1(a),crystallinity (%C)of polymer matrices within composite materi-als could be calculated on the basis of a peak fitting procedure developed by Lopez Rubio et al.,17which is widely used for synthetic polymer and it is better in reflecting the crystalline content than the tradi-tional two-phase model.The method used here took into account irregu-larities in crystals that were expected to coexist in semi-crystalline materials and avoided the underes-timation(two-phase method did not consider the diffuse scattering from non-perfect crystalline struc-ture)of the crystalline ing the Leven-berg–Marquardt algorithm,a curve fitting exercise was repeated eight times with different initial inputs and Gaussian shape of the fitted curve was confirmed to reflect the best fitting results.As Ungar18suggested,the crystallinity for samples was calculated as,X c¼X n1AC i=A twhere AC i is the area under each fitted crystalline peak with index i and A t is the total area under the diffractogram pattern.Table IV outlines the peak ba-sal spacing for the nanoclay filled samples and also the relative crystallinity as calculated from the XRD raw data.Based on Table IV data,the key finding is that the addition of low molecular weight PCL to PLA and to PLA nanocomposites reduces the overall crystallinity and that the addition of nanoclay has relatively smaller impact on the growth of a crystal-line morphology during the fiber electrospinning process.The fact that the fibers were obtained with relatively higher amorphous morphology is very beneficial to drug loading efficiencies and to improve the drug dispersion within the polymer matrix.Interestingly,Figure9shows that the poly-mer–naonclay interaction is strong enough to achieve a large intercalated structure within the amorphous region,and moreover,it appears that the addition of PCL enhances this effect(Samples No.2 and4).This has significant implication in drug load-ing capacity of biopolymers where the intercalated nanoclay structure would be able to accommodate higher wt%of drug molecules.Finally,(chloroform :methanol)samples(Samples No.3and2)indicate that in presence of PCL,the polymer–solvent inter-action is capable of dispersing the nanoclay within the polymer matrix;from two distinct morphologies appearing at around2y¼$9 (nearly exfoliated) and around2y¼$22 (long-range ordered struc-ture)for PLA only samples,a single broad amor-phous region was seen with the addition of PCL (Sample No.2).The DSC results in Table IV shows that by blend-ing PLA with PCL there was a significant decrease in T g compared with the fibers produced with PLA (about a20 C reduction).Nevertheless,there was only a small change in T m.Additional2%of HNT led to a small decrease in T g values for PLA:PCL blend nanofibers except for pure PLA in(DCM: DMF)and PLA:PCL with2wt%of HNT dissolved in(chloroform:methanol).However,the T m values again showed no significant change for most sam-ples.The interesting aspect was the apparent influ-ence of solvents on the T g and T m values oftheFigure9X-ray diffraction plots for selected samples showing the relative position of the intercalation peak due to addition of nanoclay in PLA or PLA-PCL samples with different solvents.[Color figure can be viewed in the online issue,which is available at .]TABLE IIISummaries of the Average Fiber Diameters(in nm)for All Structures with HNTCosolventsPLA:PCL(1:0)PLA:PCL(3:1)PLA:PCL(1:1)1%HNT2%HNT1%HNT2%HNT1%HNT2%HNTDMF:DCM950(645)1100(645)730(675)NA NA NA All fiber diameters are in nm and NA refers to no fiber obtained.ELECTROSPUN PLA/PCL FIBERS WITH TUBULAR NANOCLAY3937Journal of Applied Polymer Science DOI10.1002/appblends.For example,PLA in(DCM:DMF)showed a T g of62.87 C and T m of157.96 C while,PLA in(chlo-roform:methanol)showed a T g value of66.41 C and T m value of155.41 C.Moreover,in presence of2% nanoclay,the above two samples in their respective solvents showed T g values of64.75and58.51 C, respectively.Given this increasing–decreasing behavior with the addition of nanoclays,at this stage it is diffi-cult to confirm whether such effect was dominated by the solvent mixture.It is also seen that the addition of low molecular weight PCL to the PLA matrix lowered the overall crystallinity,and this is evident from the smaller D H m values for the PLA:PCL blends regard-less of the solvent used.In summary,the DSC data strongly suggest that the solvent mixture of chloro-form:methanol helps the PLA matrix attain relatively great structural orderness(slightly higher crystallinity but larger enthalpy value)and the addition of PCL matrix enhances the intercalated structure.CONCLUSIONSThis investigation focused on the morphological evo-lution of PLA and blends of PLA with low molecu-lar weight PCL reinforced with different concentra-tions of tubular halloysite nanoparticles and different cosolvents using fiber electrospinning.The fibers produced from the DCM:DMF system with-out HNT nanoparticles were more uniform,resulting in smaller fiber diameters as compared to chloro-form:methanol system and this is directly related to the increased solution conductivity in the case of DCM:DMF mixture.The addition of HNT nanopar-ticles produced fibers with large diameters because the solution viscosity increased by the addition of HNT.HNT also increased solution conductivity for chloroform:methanol cosolvent with PLA-PCL blend,which resulted in uniform fibers,especially in PLA:PCL system with polymer ratio of3:1In addition,the high volatility of methanol allowed faster solvent evaporation leading to fibers with smaller diameters.Electrospun PLA and its blends in DCM:DMF with HNT produced significantly thicker fibers as compared to samples without HNT, which was attributed to the increasing viscosity and low volatility of the solvent to negate the effects of higher conductivity of the solution.Key insights into processing blends of PLA-PCL were obtained including(1)the choice of cosolvent is important in determining fiber diameters of PLA-PCL blend because the cosolvents strongly influence the viscos-ity and conductivity of the bulk solution;(2)the dis-persion of nanoparticles and their interaction with low molecular weight polymers such as PCL is sig-nificant in that their interactions influence the solu-tion viscosity and conductivity to determine the fiber diameter;(3)there was a slighter growth of a crys-talline morphology during the fiber electrospinning process when the interactions between low molecu-lar weight PCL and HNT had happened;(4)when compared to the different cosolvents,the solvent mixture of chloroform:methanol is more suitable for PLA based systems because it can increase the structural orderness in PLA matrix.The authors acknowledge Curtin Microscopy unit for techni-cal assistance for the SEM.The authors also thank Applied Physics lab for assisting with XRD.References1.Han,J.;Chen,T.;Branford-White,C.;Zhu,L.Int J Pharm2009,382,215.2.Cui,W.;Li,X.;Zhu,X.;Yu,G.;Zhou,S.;Weng,J.Biomacro-molecules2006,7,1623.3.Heydarkhan-Hagvall,S.;Schenke-Layland,K.;Dhanasopon,A.;Rofail, F.;Smith,H.;Wu,B.;Shemin,R.;Beygui,R.;MacLellan,W.Biomaterials2008,29,2907.4.Kim,K.;Luu,Y.;Chang,C.;Fang,D.;Hsiao,B.;Chu,B.;Had-jiargyrou,M.J Controlled Release2004,98,47.5.Luong-Van,E.;Grøndahl,L.;Chua,K.;Leong,K.;Nurcombe,V.;Cool,S.Biomaterials2006,27,2042.6.Kenawy,E.;Abdel-Hay,F.;El-Newehy,M.;Wnek,G.MaterChem Phys2009,113,296.7.Touny,A.;Lawrence,J.;Jones,A.;Bhaduri,S.J Mater Res2010,25,857.TABLE IVThe DSC Results for PLA and PLA:PCL Nanocomposites with and Without HNT and with Different Cosolvents Sample X c(%)*T g( C)T m( C)D H m(J gÀ1) PLA–(DCM:DMF)18.7562.87157.9631.16 PLA–2%HNT(DCM:DMF)15.4664.75155.3630.9 PLA–chloroform:methanol12.5866.41155.4125.64 PLA–2%HNT(chloroform:methanol)13.4558.51153.9124.79 PLA–(chloroform:acetone)15.7863.22155.1625.42 PLA–2%HNT(chloroform:acetone)9.1258.89155.1223.38 PLA:PCL,3:1,DCM:DMF 5.4546.43153.9317.05 PLA:PCL,3:1,2%HNT(DCM:DMF) 3.1644.13153.8915.23 PLA:PCL,3:1,(chloroform:methanol)8.7245.62154.4724.57 PLA:PCL,3:1,2%HNT(chloroform:methanol) 4.2446.44154.4117.15 Calculation were repeated for three sets of samples and standard deviation for the T g and T m values are<1%.3938HAROOSH,CHAUDHARY,AND DONG Journal of Applied Polymer Science DOI10.1002/app8.Arumugam,G.;Khan,S.;Heiden,P.Macromol Mater Eng2009,294,45.9.Buschle-Diller,G.;Cooper,J.;Xie,Z.;Wu,Y.;Waldrup,J.;Ren,X.Cellulose2007,14,553.10.Han,J.;Branford-White,C.;Zhu,L.Carbohydr Polym2010,79,214.11.Haque,P.;Barker,I.;Parsons,A.;Thurecht,K.;Ahmed,I.;Walker,G.;Rudd,C.;Irvine,D.J Polym Sci A Polym Chem 2010,48,3082.12.Pham,Q.;Sharma,U.;Mikos,A.Tissue Eng2006,12,1197.13.Bhardwaj,N.;Kundu,S.Biotechnol Adv2010,28,325.14.Jiang,H.;Fang,D.;Hsiao,B.;Chu,B.;Chen,W.Biomacromo-lecules2004,5,326.15.Um,I.;Fang,D.;Hsiao,B.;Okamoto,A.;Chu,B.Biomacromo-lecules2004,5,1428.16.Hsu,F.;Hung,Y.;Liou,H.;Shen,C.Acta Biomater2010,6,2140.17.Lopez Rubio,A.;Flanagan,B.;Gilbert,E.;Gidley,M.Biopoly-mers2008,89,761.18.Ungar,T.Script Mater2004,51,777.ELECTROSPUN PLA/PCL FIBERS WITH TUBULAR NANOCLAY3939Journal of Applied Polymer Science DOI10.1002/app。
复合材料层合圆柱壳的振动特性
复合材料层合圆柱壳的振动特性谭安全;刘敬喜;李天匀;朱翔【摘要】文章基于Love壳体理论,对复合材料层合圆柱壳的振动特性进行了研究.通过比较,文中计算方法所得的结果与文献比较吻合.运用该方法,讨论了简支、固支和自由等边界条件,轴向模态和铺层角度对圆柱壳振动特性的影响.分析表明,在低阶周向模态时,边界条件和轴向模态的影响更大.%Based on the Love theory, the vibrational characteristics of laminated composite cylindrical shell are studied. The obtained results were evaluated with those in the literature and both are in agreement. With this method, the influences of boundary conditions, axial modes and fiber angles on the vibrational charac-teristics of cylindrical shell are investigated. It is concluded that the influences of boundary conditions and axial modes can be seen to be more significant at small circumferential modes than at large circumferential modes.【期刊名称】《船舶力学》【年(卷),期】2017(021)008【总页数】6页(P1035-1040)【关键词】复合材料圆柱壳;振动;边界条件;周向模态【作者】谭安全;刘敬喜;李天匀;朱翔【作者单位】中国船级社重庆分社,重庆 401121;华中科技大学船舶与海洋工程学院,武汉 430074;华中科技大学船舶与海洋工程学院,武汉 430074;华中科技大学船舶与海洋工程学院,武汉 430074【正文语种】中文【中图分类】O343复合材料因其自身的高比强度、比刚度和减振性能好等优点，现已广泛应用于各工程领域中。
机械类汽车转向系统外文文献及翻译
1 IntroductionThe key task for the automobile industry and its suppliers in future lies in speedily developing and implementing ecologically sound and economically justifiable mobility systems. Light metals such as aluminum and magnesium along with glass and carbon fiber reinforced materials, ceramics and composites have opened up the potential for considerable weight reduction and for "green" vehicle concepts which can be realized economically. Aluminum in particular can provide the impetus for new designs for the next millennium. Decades ago, the use of aluminum in auto construction was seen as an "experiment"; Today it is a vital factor in reducing weight and thus lowering fuel consumption.The average passenger car today contains 60 to 70 kg of aluminum, and current developments point to a doubling of this amount in the next few years. Motor vehicles both now and in future must meet requirements for: greater performance, greater safety, comfort, low pollution. Lightweight construction is not just about reducing weight; it is a question of -striking the right balance between reduced weight and structural efficiency. In vehicle construction this normally means making the best use of the generally very tight space available for individual components so as to allow weight to be minimized while still meeting all stiffness, strength, natural frequency or acoustical requirements. To achieve this, stresses must be distributed throughout the structure as evenly as possible. Modern numerical analysis methods such as FEA allow a very detailed analysis of system behavior, provide cost-efficient support for the complex process of optimization and thus make a huge contribution to advances in lightweight construction. Packaging, safety considerations, reproducibility and price place restrictions on the degree of weight reduction achievable.The broad range of expertise available to Krupp Presta AG allows the company to analyze customer specifications for steering systems and provide appropriate solutions.2 Requirements to be met by steering systemsThe steering is an important part of the feel of a car. The steering system should make driving an enjoyable experience with no unpleasant vibration from the road surface while guaranteeing the required hand- sing. It is also important that high safety requirements be met, both under normal conditions and in crash situations. The key criteria for the steering system are thus as follows:rolling friction, torsional stiffness /strength, Damping, temperature, corrosion, durability / fatigue, weight. Crash kinematics and energy absorption steering column requirements:natural frequency / stiffness, mass, damping, space, strength (crash, misuse), ergonomics, handling, acoustics, crash kinematics and energy absorption. Other basic conditions:interfaces with adjacent components, installation, joining techniques, price.3 Materialsmaterial light weighting can be achieved by using either stronger or lighter material. When stiffness or natural frequency are Important sizing criteria, low density materials with a high modulus of elasticity by quired. Non-exotic materials must be selected which are readily recyclable, low in price and display good durability.Further requirements are set by the manufacturing and joining processes. Steel, aluminum, magnesium and a variety of plastics are the materials of choice for steering systems.Low specific gravity, high corrosion resistance, low fabricating costs, high energy absorption and good recycle ability make aluminum a favored light weighting material. Owing to its high energy content, up to 90% of the aluminum used in auto construction can be recycled (intelligent design / no mixing with other materials). The favorable energy balance of aluminum puts it at a great advantage over many other materials.In environmental terms aluminum scores highly. The large amounts of primary energy required to make raw aluminum are offset over the lifetime of the vehicle. Composites could also become a very attractive proposition on account of their extreme stiffness, low weight and energy absorption capabilities. At present, howler, price is a problem, as are joining and quality assurance.4 Reducing component weightA focused strategy to reduce component weight requires a lightweight approach to design (force distribution, stresses), material (material selection), specifications (modified, realistic specifications)Key factors in lightweight design include [1]: force flows, material properties, ambient conditions ® safety requirements, reliability of joints, manufacture ability. Practical experience has shown that car makers' specifications based on steel need to be revised for lightweighting. Requirements valid for a steel steering shaft, for example, can result in severe oversizing of an aluminum shaft. Reducing component weight requires material compatible designs combined with material- compatible specifications.5 Lightweight componentsAs part of its development program Krupp Presta is replacing conventional steel steering components such as steering rods , shafts or forks with corresponding aluminum components produced by new processes. Weight savings of 20-30% are achievable depending on the basic conditions stipulated by the customer. Aluminum and magnesium die castings are already being used in steering columns , and further opportunities for weight reduction are being investigated. The lightweight steering column (Fig. 1) produced by Krupp Presta for the Audi A6 is a good example. By using magnesium die castings it has been possible to limit the weight of the steering column to just 5kg, a reduction of 15-20% over conventional (steel) designs.6 Steering column designExperience has shown that it is possible to design steering columns for cars more or less on the basis of their natural frequency alone. Additional engineering work may be required to design critical parts which must not break in the case of a crash or misuse (e.g. theft). The main task when engineering a steering column is thus to achieve the highest possible natural frequencies while minimizing weight. Low-stiffness components are being analyzed and refined in an effort to achieve uniform loading of the structure. In solving this task, use is made of numerical methods such as FEA. The structure is divided into finite elements which are characterized by specific deformation assumptions. Using FE analysis it is possible to examine complex structures, analyze sensitivities and links, discuss variations or ways of making improvements and optimize the structure numerically. Topological optimization is carried out for the analysis of low-stress areas and for the basic design of ribs and beads. CAD geometrydata are processed in an FE pre-processor. Correct modeling of the following is essential, individual parts, stiffness, contact faces, kinematics mass. Modeling is followed by computation and evaluation of the data obtained. The deformation energy is a global measure for assessing stresses. Normalizing the element deformation energy by the element mass provides information on the stresses acting on the element relative to its mass. The kinetic energy is regarded as the influence of vibrating masses which have a negative effect on the natural frequency of the steering column. By evaluating stress and strain conditions, highly localized weak points or high-stress areas can be identified.7 ConclusionsExisting technologies must be continuously adapted and improved in line with the requirements of the auto industry. Systematic weight reduction is a major challenge and requires close cooperation between vehicle manufacturers and suppliers. Materials, fabricating and joining technologies must be further refined. One prerequisite for the continuing success of Krupp Presta is the flexibility to react to customer wishes and requirements.Reference[1] Klein, B.:Leichtbau-Konstruktion. Berech- nungsgrundlagen und Gestaltung.Braunschweig: Vieweg, 1997一、简介汽车工业及其供应商，在未来的关键任务在于迅速制定和实施无害生态和经济上合理流动系统。
怎样描述rd图谱
Superior Performance Asymmetric Supercapacitors Based on a Directly Grown Commercial Mass 3D Co3O4@Ni(OH)2Core−ShellElectrodeFacile Synthesis of Hollow MoS2Microspheres/Amorphous Carbon Composites and Their Lithium Storage PropertiesBroad and weak peakIn situ assembly of MnO2nanowires/graphene oxide nanosheets composite with high specific capacitancestrong and clear peakNickelecobalt hydroxide nanosheets arrays on Ni foamfor pseudocapacitor applicationsOne-pot hydrothermal synthesis of reduced graphene oxide/Ni(OH)2 films on nickel foam for high performance supercapacitorsRapid synthesis of graphene/cobalt hydroxide composite with enhanced electrochemical performance for supercapacitorsSynthesis of ultrathin mesoporous NiCo2O4nanosheets on carbon fiber paper as integrated high-performance electrodes for supercapacitorsA sandwich-type three-dimensional layered double hydroxide nanosheet array/graphene composite: fabrication and high supercapacitor performanceUltrathin and highly-ordered CoO nanosheet arrays for lithium-ion batteries with high cycle stability and rate capabilityNi–Co sulfide nanowires on nickel foam withultrahigh capacitance for asymmetricsupercapacitorsOn e-step synthesis of CoNi2S4 nanoparticles for supercapacitor electrodes3D Ni3S2 nanosheet arrays supported on Ni foamfor high-performance supercapacitor and nonenzymatic glucose detectionHigh-performance NiCo2O4@Ni3S2 core/shell mesoporous nanothorn arrays on Ni foam for supercapacitorsNickele Cobalt hydroxide microspheres electrodepositioned on nickelcobaltite nanowires grown on Ni foam for high-performance pseudocapacitorsA novel porous coral-like as an anode material for lithium ion batteries with excellent rate performanceHydrated Cobalt Nickel Molybdate Nanorods as Effectively Supercapacitor Electrode MaterialsMicrowave-assisted synthesis of graphene/CoMoO4 nanocompositeswith enhanced supercapacitor performanceCoMoO4$ nanorods grown on reduced graphene oxide as advanced electrochemical pseudocapacitor materialsFacile fabrication and perfect cycle stability of 3D NiO@CoMoO4 nanocomposite on Ni foam for supercapacitorsFacile hydrothermal synthesis of hierarchical ultrathin mesoporousNiMoO4 nanosheets for high performance supercapacitorsNano a-NiMoO4 as a new electrode for electrochemical supercapacitorsComparison of the Electrochemical Performance of NiMoO4 Nanorods and Hierarchical Nanospheres for Supercapacitor ApplicationsSeaurchin-like hierarchical NiCo2O4@NiMoO4core–shell nanomaterials for high performance supercapacitorsControlled Growth of NiMoO4 Nanosheet andNanorod Arrays on Various Conductive Substrates as Advanced Electrodes for Asymmetric SupercapacitorsDesign and synthesis of 3D Co3O4@MMoO4 (M=Ni, Co) nanocomposites as high-performance supercapacitor electrodesEnhanced performance of supercapacitors with ultrathin mesoporous NiMoO4 nanosheets。
稀土元素对轧制Mg–Zn–Zr_合金板材微观组织和力学性能的影响
128精密成形工程 2023年7月[9] HUANG Meng, XU Chao, FAN Guo-hua, et al. Role ofLayered Structure in Ductility Improvement of LayeredTi-Al Metal Composite[J]. Acta Materialia, 2018, 153: 235-249.[10] 王锟. 基于内聚力-GTN混合模型的钛-铝层状复合板损伤研究[D]. 洛阳: 河南科技大学, 2018: 43-46.WANG Kun. Study on Damage of Ti-Al Laminated Composite Plate Based on CZM-GTN Hybrid Model[D].Luoyang: Henan University of Science and Technology,2018: 43-46.[11] 郭照灿. 铜/铝双金属复层材料应变光学检测及力学性能研究[D]. 郑州: 郑州轻工业大学, 2022: 31-42.GUO Zhao-can. Optical Strain Detection and Mechani-cal Properties of Cu/Al Bimetallic Clad Materials[D].Zhengzhou: Zhengzhou University of Light Industry, 2022: 31-42.[12] 李莎, 贾燚, 刘欣阳, 等. 层状镁/铝复合板轧制工艺研究进展[J]. 精密成形工程, 2021, 13(6): 1-11.LI Sha, JIA Yi, LIU Xin-yang, et al. Research Progresson Rolling Process of Laminated Mg/Al Clad Plate[J].Journal of Netshape Forming Engineering, 2021, 13(6):1-11.[13] 高勃兴, 邹德坤, 谢红飙, 等. 铝/钢轧制复合有限元二次开发模拟与实验研究[J]. 精密成形工程, 2021, 13(6): 56-63.GAO Bo-xing, ZOU De-kun, XIE Hong-biao, et al.Simulation and Experimental Study on Finite Element Secondary Development of Aluminum/Steel Rolling Composite[J]. Journal of Netshape Forming Engineering, 2021, 13(6): 56-63.[14] LIU H S, ZHANG B, ZHANG G P. Enhanced Tough-ness and Fatigue Strength of Cold Roll Bonded Cu/Cu Laminated Composites with Mechanical Contrast[J].Scripta Materialia, 2011, 65(10): 891-894.[15] HUANG M, CHEN J S, WU H, et al. Strengthening andToughening of Layered Ti-Al Metal Composites by Controlling Local Strain Contribution[J]. IOP Confer-ence Series: Materials Science and Engineering, 2017, 219: 012028.[16] LI Z, LIN Y C, ZHANG L, et al. In-situ Investigation onTensile Properties of a Novel Ti/Al Composite Sheet[J].International Journal of Mechanical Sciences, 2022, 231: 107592.[17] HUANG C X, WANG Y F, MA X L, et al. InterfaceAffected Zone for Optimal Strength and Ductility inHeterogeneous Laminate[J]. Materials Today, 2018, 21(7): 713-719.[18] CHEN Wen-huan, HE Wei-jun, CHEN Ze-jun, et al.Extraordinary Room Temperature Tensile Ductility ofLaminated Ti/Al Composite: Roles of Anisotropy andStrain Rate Sensitivity[J]. International Journal of Plas-ticity, 2020, 133: 102806.[19] XING Bing-hui, HUANG Tao, XU Liu-jie, et al. Effectof Heat Treatment Process on the Microstructure of theInterface of Ti/Al Laminated Composite[J]. CompositeInterfaces, 2022, 29(7): 749-764.[20] 金属材料拉伸试验第1部分: 室温试验方法: GB/T228. 1—2010[S]. 2011.Metallic Materials-Tensile Testing-Part 1: Method ofTest at Room Temperature: GB/T 228.1—2010[S]. 2011.[21] 杨方方, 皇涛, 陈拂晓, 等. 异质金属层状复合板分层应力-应变关系研究[J]. 塑性工程学报, 2018, 25(1):187-191.YANG Fang-fang, HUANG Tao, CHEN Fu-xiao, et al.Research on Delamination Stress-Strain Relationship ofHeterostructure Laminated Composite Sheets[J]. Journalof Plasticity Engineering, 2018, 25(1): 187-191.[22] HUANG Tao, PEI Yan-bo, CHEN Fu-xiao, et al. ANovel Layered Finite Element Model for Predicting theDamage Behavior of Metal Laminated Composite[J].Composite Structures, 2023, 311: 116786.[23] TVERGAARD V, HUTCHINSON J W. The Relationbetween Crack Growth Resistance and Fracture ProcessParameters in Elastic-Plastic Solids[J]. Journal of theMechanics and Physics of Solids, 1992, 40(6): 1377-1397.[24] GURSON A L. Continuum Theory of Ductile Ruptureby Void Nucleation and Growth: Part I-Yield Criteriaand Flow Rules for Porous Ductile Media[J]. Journal ofEngineering Materials and Technology, 1977, 99(1): 2-15.[25] TVERGAARD V. Influence of Voids on Shear BandInstabilities under Plane Strain Conditions[J]. Interna-tional Journal of Fracture, 1981, 17(4): 389-407.[26] HUANG M, FAN G H, GENG L, et al. Revealing Ex-traordinary Tensile Plasticity in Layered Ti-Al MetalComposite[J]. Scientific Reports, 2016, 6(1): 1-10.责任编辑：蒋红晨第15卷 第7期 精 密 成 形 工 程2023年7月JOURNAL OF NETSHAPE FORMING ENGINEERING129收稿日期：2023‒03‒22 Received ：2023-03-22基金项目：国家自然科学基金（52001188）Fund ：National Natural Science Foundation of China (52001188)作者简介：孙捷（1988—），男，博士，讲师，主要研究方向为镁合金塑性变形机理Biography ：SUN Jie (1988-), Male, Doctor, Research focus: plastic deformation mechanism of magnesium alloy. 引文格式：孙捷, 曲京儒, 阎玉芹, 等. 稀土元素对轧制Mg–Zn–Zr 合金板材微观组织和力学性能的影响[J]. 精密成形工程, 2023, 15(7): 129-135.SUN Jie, QU Jing-ru, YAN Yu-qin, et al. Effect of Rare Earth (RE) on Microstructure and Mechanical Property of Rolled 稀土元素对轧制Mg–Zn–Zr 合金板材微观组织和力学性能的影响孙捷，曲京儒，阎玉芹，赵彦华（山东建筑大学 机电工程学院，济南 250101）摘要：目的 为了使Mg–Zn–Zr 合金在热加工过后具有良好的力学性能及变形各向同性，在Mg–2Zn–0.5Zr 合金中添加不同含量的稀土元素，研究稀土元素对Mg–2Zn–0.5Zr 合金轧制后微观组织和力学性能的影响规律，以解决变形镁合金织构强、变形各向异性强的问题。
生物陶瓷英文文献
Fabrication and Mechanical Properties of Dense/Porous β-TricalciumPhosphate BioceramicsFaming Zhang1, a , Jiang Chang 1, b*, Jianxi Lu 1, 2, c , Kaili Lin 1, d 1 Biomaterials and Tissue Engineering Research Center, Shanghai Institute of Ceramics, ChineseAcademy of Sciences, Shanghai 200050, China 2 Shanghai Bio-lu Biomaterials Company, Shanghai 200335, China a star.zhang@, b* jchang@,c ir2bberck@,d lklsic@Keywords: Bioceramics, calcium phosphate, bone regeneration, weight bearing sitesAbstract: Attempt t o increase the mechanical properties of porous bioceramics, a dense/porous structured β-TCP bioceramics that mimic the characteristics of nature bone were fabricated. Experimental results show that the dense/porous structured β-TCP bioceramics demonstrated excellent mechanical properties with compressive strength up to 74 MPa and elastic modulus up to 960 MPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of exponential growth. The interface between the dense and porous bioceramics is connected compactly and tightly with some micropores distributed in the matrix of both porous and dense counterparts. The dense/porous structure of β-TCP bioceramics may provide an effective way to increase the mechanical properties of porous bioceramics for bone regeneration at weight bearing sites.IntroductionVarious methods for bone defect treatments have been developed using biological or synthetic grafts. The synthetic alternatives are promising grafts for their unlimited availability and without risk of disease transmission [1]. Calcium phosphate bioceramics, especially hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), have been extensively explored as bone grafts due to their compositions are similar to the inorganic components of nature bone [2]. The β-TCP bioceramics is well known as a biodegradable material demonstrated clinical efficacy. The porous β-TCP bioceramics is a structurally biomimetic of the cancellous bone, whose porous network could allow tissue to ingrowth exhibiting nicer osteoconductive properties. However, the porous β-TCP shows weak mechanical properties, which limit its application as bone grafts. The macrostructure feature of nature bone is porous cancellous bone inside with dense compact bone surrounding outside, which provides excellent biomechanical properties. Carotenuto et al [3] have prepared dense/porous layered HA bioceramic for orthopedic device coating by tape casting technique, whereas the bulk dense/porous bioceramics were rarely reported. Therefore in present study, a dense/porous structured β-TCP bioceramics that mimics the characteristics of nature bone were fabricated, and the microstructure and mechanical properties of such bioceramics were studied.ExperimentalThe β-TCP powders were synthesized by chemical precipitation reaction. The dense/porous structured β-TCP bioceramics were prepared by injected molding and subsequently pressureless sintering. The shrinkage rate of both porous and dense parts during sintering process was measured at different temperatures. X-ray diffraction (XRD) with Cu K α radiation was used to characterize the phase composition of the ceramics. The microstructures observation of the bioceramic samples was performed on a scanning electron microscopy (SEM).The compressive strength was conducted with a mechanical tester at 0.5 mm/min crosshead speed. The elastic modules were reanalyzed from the slope of the compressive strength-strain curve.All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of the publisher: Trans Tech Publications Ltd, Switzerland, . (ID: 159.226.129.129-19/09/06,02:35:46)Results and DiscussionThe major problem in preparation of the dense/porous bioceramics is the interface adhesion between the dense and porous parts because of their different shrinkage rate during sintering process. The shrinkage rate of dense and porous bioceramics at different temperatures was measured and the results are shown in Fig.1. It can be noticed that the porous β-TCP bioceramics exhibit much higher shrinkage rate than the dense counterpart. The porous bioceramics shows about 23% shrinkage in radial direction; in contrast, the dense bioceramics presents about 17% shrinkage. It can be calculated that from 850 o C to 1100 o C, the porous β-TCP bioceramics shows about 17% shrinkage rate and almost the same with that of the dense counterpart from 600 o C to 1100 o C. So as to avoiding the shrinkage differences, the porous β-TCP bioceramics were pre-sintered at 850 o C, then the dense bioceramics were injected surrounding the porous ceramics, finally the composites were pressureless sintered at 1100 o C for 5 hours and the dense/porous structured β-TCP bioceramics were obtained.Fig.1 The radial shrinkage rate of the porous and dense β-TCP bioceramicsThe phase composition of the as prepared bioceramics was analyzed by X-ray diffraction. The XRD results show that the high temperature sintered β-TCP preserved their original β phase without transform into their α-TCP phase, as shown in Fig.2. Because the α-TCP though bioactive, have proven less useful as bone regeneration materials due to their excessively high resorption rate than the β-TCP phase. And none of the other impurity phases can be detected in the XRD patterns; resultantly, high purity β-TCP bioceramics were prepared.Fig.2 X-ray diffraction pattern of the prepared bioceramics.Fig.3 shows the optical and SEM micrographs of the prepared dense/porous β-TCP bioceramics samples. It is clear to see that the inner porous structure mimics the cancellous bone to some extent, and outer side dense structure mimics the compact bone, as shown in Fig.3(a) and indicated by theS h i n k a g e (%)Temperature (o C)1020304050607080100200300400500600 2theta (deg.)I n t e n s i t y (c p s )arrows. Fig.3 (b) shows the interface of the dense/porous β-TCP bioceramic, it can be found that the interface between the dense and porous bioceramics is connected compactly and tightly. In the porous part, the macropore size is about 500 μm in diameter; the diameter of the interconnected pores is about 100 μm. Additionally, the porosity of the porous parts is about 72%, and the interconnectivity is more than 95%. The microstructure of the macroporous wall was shown in Fig.3(c); it is obvious that there are some micropores with diameter of 1 μm distributed uniformly in the porous wall. As the results, the microstructure of porous part of the bioceramics is a combination of macroporous and microporous. Contrastively, the microstructure of the dense bioceramics shows refined particle size and few micropores, as exhibited in Fig.3(d). The dense compact part is much denser than the porous cancellous part.Fig.3 The dense/porous β-TCP bioceramic sample (a), the microstructure of dense/porous interface(b), the macroporous wall (c) and dense compact bone (d).The variation of the compressive strength and Elastic modulus of the bioceramics with different dense/porous cross-sectional area ratio (S dense /S porous ) was illustrated in Fig 4. It is exhibited that the compressive strength increases from 10 MPa to 74 MPa with the dense/porous ratio from 0.1 to 4.7 obeying rule of exponential growth. And the elastic modulus has been increased form 180 MPa to 960 MPa with the dense/porous ratio increment, also following exponential growth. Evidently, the value of the porous bioceramics is only about 2.0 MPa and the elastic modulus is about 20 MPa, indicated by the square in Fig.4. It has been achieved about 5 to 37 times increment in the mechanical properties by the dense/porous structure design. The mechanical properties of the dense/porous bioceramics could be tailored by the dense/porous cross-sectional area ratio.Porous materials always have poor mechanical properties. Applications of calcium phosphates in the body have been limited by their low strength and numerous techniques have been investigated in attempts to retain their useful bioactive properties whilst providing more suitable mechanical properties for particular applications. These include the reinforcement of β-TCP using HA fiber orbioglass additives [4, 5]; however these techniques are limited for the porous calcium phosphate Compact bone Cancellousbone (b)(c) (d)using in the load bearing sites’ bone regeneration. In this study, excellent mechanical properties of the porous β-TCP bioceramics have been achieved by the dense/porous structured design. The compressive strength of human femoral cancellous bone, weight bearing sites, is in the range of 25~90 MPa, so the dense/porous structured β-TCP is comparable to the strength of human femoral cancellous bone. The high interconnective porous structure of the dense/porous β-TCP bioceramics could allow the tissue ingrowths, and the dense structure could bear the load to some extent. The dense/porous structure of β-TCP bioceramics may provide a simple but effective way to increase the mechanical properties of porous bioceramics for the bone regeneration applications at weight bearing sites.Fig.4 The variation of the compressive strength and elastic modulus of the bioceramics withdifferent dense/porous cross-sectional area ratio. ConclusionsThe dense/porous structured β-TCP bioceramics were prepared and revealed excellent mechanical properties with compressive strength from 10 to 74 MPa and elastic modulus from 180 to 960 MPa, which is 5 to 37 times higher than that of the pure porous β-TCP and comparable to the strength of human femoral cancellous bone. The interface between the dense and porous bioceramics is connected compactly and tightly. The dense/porous structure of β-TCP bioceramics may provide a simple but effective way to increase the mechanical properties of porous bioceramics for weight bearing site’s bone regeneration.AcknowledgementFinancial supports from the Shanghai Postdoctoral Scientific Key Program and the Science & Technology Commission of Shanghai Municipality of China (No.04DZ52043) are greatly acknowledged.References:[1] Niedhart C, Maus U, Redmann E, Schmidt-Rohlfing B, Niethard FU, Siebert CH: J BiomedMater Res Vol. 65A (2003), p.17[2] Hench Larry L: Journal of the American Ceramic Society Vol. 81(1998), p.1705[3] Carotenuto G: Advanced Performance Materials Vol. 5(1998), p.171[4] Hassna R. R. Ramay, Zhang M.: Biomaterials Vol. 25(2004), p.5171[5] Ashizuka M, Nakatsu M, Ishida E: Journal of the Ceramic Society of Japan, v 98(1990), p.204. 01020304050607080012345020040060080010001200E l a st i c M o d u l u s (M P a ) C o m p r e s s i v e S t r e n g h (M P a )S dense /S porous。
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先丰客户发表文章Publications Featuring XFNANO Graphene, Carbon Nanotubes and Others.此统计数据日期截至2014年02月22日，由于文章较多，此处仅统计先丰客户英文文章且直接引用先丰公司英文名称”Nanjing XFNANO Materials Tech Co.,Ltd”,截至到现在已经有超过500篇文章(包括英文/中文/专利)署名先丰纳米，我司现整理出242篇高质量英文文章，总影响因子超过1000，平均影响因子3.993。
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另外我司代理的产品，国内客户发表文章的也有上百篇，由于署名不是我司，较难查找，我司以后会摘录几篇影响因子较高的客户文章，同时也欢迎客户反馈文章发表信息。
反馈一篇我司此列表中未摘录的英文文章包括会议论文奖励一百元，作者亲自反馈的除奖金外，购买我司产品一律享受VIP待遇。
以下为影响因子和文章概述，经我司计算，客户以我司名义发表SCI文章影响因子平均高达：3.993影响因子(Impact Factor)概述：大于等于10：期刊：Advanced Materials 2013 影响因子：14.829文章Vertically Oriented Graphene Bridging Active-Layer/Current-Collector Interface for Ultrahigh Rate Supercapacitors期刊：Advanced Functional Materials 2012 影响因子：10.179文章: Layered H2Ti6O13-Nanowires: A New Promising Pseudocapacitive Material in Non-Aqueous Electrolyte南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China大于等于6：期刊：Nanoscale 2014 影响因子：6.233文章：Vertical junction photodetectors based on reduced graphene oxide/silicon Schottky diodes.期刊：Biomaterials 影响因子：7.604文章：Inhibitory effect of silver nanomaterials on transmissible virus-induced host cell infections.期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章A general strategy to prepare homogeneous and reagentless GO/lucigenin&enzyme biosensors for detection of small biomolecules期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Simultaneous electrochemical detection of cervical cancer markers using reduced graphene oxide-tetraethylene pentamine as electrode materials and distinguishable redox probes as labels期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Electrochemical determination of cefotaxime based on a three-dimensional molecularly imprinted film sensor期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin–copper(II) complex as the DNA intercalator期刊：analytical chemistry 2014 影响因子： 5.695文章 A Homogeneous Signal-On Strategy for the Detection of rpoB Genes of Mycobacterium tuberculosis Based on Electrochemiluminescent Graphene Oxide and Ferrocene Quenching期刊：Biosensors and Bioelectronics 2014影响因子： 5.437文章Investigation of the effect of phytohormone on the expression of microRNA-159a in Arabidopsis thaliana seedlings based on mimic enzyme catalysis systematic electrochemical biosensor期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Target-induced electronic switch for ultrasensitive detection of Pb2+ based on three dimensionally ordered macroporous Au–Pd bimetallic electrode期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Electrochemical immunoassay for procalcitonin antigen detection based on signal amplification strategy of multiple nanocomposites期刊：Carbon 2014 影响因子： 5.868文章Enhanced nonlinear optical and optical limiting properties of graphene/ZnO hybrid organic glasses期刊：Carbon 2014 影响因子： 5.868文章Reductive dechlorination of hexachloroethane by sulfide in aqueous solutions mediated by graphene oxide and carbon nanotubes文章Facile and novel electrochemical preparation of a graphene–transition metal oxide nanocomposite for ultrasensitive electrochemical sensing of acetaminophen and phenacetin期刊：Biomaterials 2014 影响因子：7.604文章Graphene oxide doped conducting polymer nanocomposite film for electrode-tissue interface 期刊：Nanoscale 2014 影响因子：6.233南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China文章Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres期刊：Journal of Materials Chemistry A 2014 影响因子： 6.101文章Binder-free phenyl sulfonated graphene/sulfur electrodes with excellent cyclability for lithium sulfur batteries期刊：Journal of Materials Chemistry A 2014 影响因子： 6.101文章A 3D hierarchical porous α-Ni(OH)2/graphite nanosheet composite as an electrode material for supercapacitors期刊：Chemical Communications 2012 影响因子：6.169文章: Graphene electrochemical supercapacitors: the influence of oxygen functional groups期刊：Advanced Functional Materials 2013 影响因子：9.765文章Highly Electron Transparent Graphene for Field Emission Triode Gates期刊：Biomaterials 2013 影响因子：7.604文章Nanodiamonds-mediated doxorubicin nuclear delivery to inhibit lung metastasis of breast cancer期刊：Nanoscale 2013 影响因子：6.233期刊：Nanoscale 2013 影响因子： 6.233文章Using ruthenium polypyridyl functionalized ZnO mesocrystals and gold nanoparticle dotted graphene composite for biological recognition and electrochemiluminescence biosensing期刊：Nanoscale 2013 影响因子： 6.233文章One-pot, water-based and high-yield synthesis of tetrahedral palladium nanocrystal decorated graphene期刊：Journal of Materials Chemistry A 2013影响因子：6.101文章Graphene-wrapped silver/porous silicon composite with enhanced electrochemical performance for lithium-ion batteries期刊：Biomaterials 2013 影响因子：7.604文章:Protein-assisted fabrication of nano-reduced graphene oxide for combined in vivo photoacoustic imaging and photothermal therapy大于等于5：期刊：Biosensors and Bioelectronics 2014 影响因子：5.437文章：Mild and Novel Electrochemical Preparation of β-Cyclodextrin/Graphene Nanocomposite Film for Super-Sensitive Sensing of Quercetin期刊：Anal. Chem. 2014 影响因子：5.695文章：In Situ Growth of Porous Platinum Nanoparticles on Graphene Oxide for Colorimetric Detection of Cancer Cells期刊：Journal of Materials Chemistry A 2013 影响因子：5.968文章: Highly loaded CoO/graphene nanocomposites as lithium-ion anodes with superior reversible capacity期刊：Journal of Materials Chemistry 2012 影响因子：5.968文章: Graphene/porous cobalt nanocomposite and its noticeable electrochemical hydrogen storage ability at room temperature南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China期刊：Journal of Materials Chemistry 2012 影响因子：5.968文章: Graphene/polyaniline nanorod arrays: synthesis and excellent electromagnetic absorption properties期刊：Journal of Materials Chemistry 2012 影响因子：5.968文章: A novel Fe3O4–graphene–Au multifunctional nanocomposite: green synthesis and catalytic application期刊：Journal of Materials Chemistry 2013 影响因子：5.968文章: Enhanced photovoltaic performance of dye-sensitized solar cells based on TiO2 nanosheets/graphene composite films期刊：Journal of Materials Chemistry A 2013 影响因子：5.968文章: Stabilization of NaZn(BH4)3via nanoconfinement in SBA-15 towards enhanced hydrogen release期刊：Applied Catalysis B: Environmental 2012 影响因子：5.625文章: Enhanced photocatalytic activity of hierarchical macro/mesoporous TiO2–graphene composites for photodegradation of acetone in air期刊：Biosensors and Bioelectronics 2012 影响因子：5.602文章: Acetylcholinesterase biosensor based on chitosan/prussian blue/multiwall carbon nanotubes/hollow gold nanospheres nanocomposite film by one-step electrodeposition期刊：Biosensors and Bioelectronics 2012 影响因子：5.602文章: Label-free colorimetric sensor for ultrasensitive detection of heparin based on color quenching of gold nanorods by graphene oxide期刊：Biosensors and Bioelectronics 2012 影响因子：5.602文章: Direct electron transfer glucose biosensor based on glucose oxidase self-assembled on electrochemically reduced carboxyl graphene期刊：Biosensors and Bioelectronics 2012 影响因子:5.602文章: DNA electrochemical biosensor based on thionine-graphene nanocomposite期刊：Carbon 2012 影响因子：5.378文章: Synthesis of electrochemiluminescent graphene oxide functionalized with a ruthenium(II) complex and its use in the detection of tripropylamine期刊：Carbon 2013 影响因子： 5.868文章Preparation and tribological properties of TiAl matrix composites reinforced by multilayer graphene期刊：Biosensors and Bioelectronics 2013 影响因子： 5.437文章Simple Approach for Ultrasensitive Electrochemical Immunoassay of Clostridium difficile toxin B Detection期刊：Biosensors and Bioelectronics 2013 影响因子： 5.437文章Target-induced Electronic Switch for Ultrasensitive Detection of Pb2+ Based on Three Dimensionally Ordered Macroporous Au-Pd Bimetallic Electrode期刊：Biosensors and Bioelectronics 2014 影响因子： 5.437文章Direct electron transfer of glucose oxidase and biosensing for glucose based on PDDA-capped gold nanoparticle modified graphene/multi-walled carbon nanotubes electrode南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China期刊：Analytical chemistry 2013 影响因子： 5.695文章Graphene Oxide–Peptide Nanocomplex as a Versatile Fluorescence Probe of Protein Kinase Activity Based on Phosphorylation Protection against Carboxypeptidase Digestion期刊：Lab on a Chip 2013 影响因子： 5.697文章On-chip selective capture of cancer cells and ultrasensitive fluorescence detection of survivin mRNA in a single living cell期刊：Environmental Science & Technology 2013 影响因子：5.257文章Graphene and g-C3N4 Nanosheets Cowrapped Elemental α-Sulfur As a Novel Metal-Free Heterojunction Photocatalyst for Bacterial Inactivation under Visible-Light期刊：Biosensors and Bioelectronics 2014 影响因子：5.437文章A highly sensitive and wide-ranged electrochemical zinc(II) aptasensor fabricated on core–shell SiO2-Pt@meso-SiO2期刊：Analytical chemistry 2013 影响因子：5.695文章Electrochemiluminescent Quenching of Quantum Dots for Ultrasensitive Immunoassay through Oxygen Reduction Catalyzed by Nitrogen-Doped Graphene-Supported Hemin期刊：Biosensors and Bioelectronics 2013 影响因子：5.437文章A novel ionic liquid stabilized molecularly imprinted optosensing material based on quantum dots and graphene oxide for specific recognition of vitamin E期刊：APPLIED MATERIALS & INTERFACES 2013 影响因子：5.008文章Dye-Sensitization-Induced Visible-Light Reduction of Graphene Oxide for the Enhanced TiO2 Photocatalytic Performance期刊：Biosensors and Bioelectronics 2014 影响因子：5.437文章Graphene oxide as nanogold carrier for ultrasensitive electrochemical immunoassay of Shewanella oneidensis with silver enhancement strategy期刊：ACS APPLIED MATERIALS & INTERFACES 2013 影响因子：5.008文章Graphene-Wrapped CoS Nanoparticles for High-Capacity Lithium-Ion Storage期刊：Biosensors and Bioelectronics 2013 影响因子：5.437文章Combination of cascade chemical reactions with graphene–DNA interaction to develop new strategy for biosensor fabrication期刊：Biosensors and Bioelectronics 2013 影响因子：5.437文章 A graphene oxide-based FRET sensor for rapid and sensitive detection of matrix metalloproteinase 2 in human serum sample期刊：Biosensors and Bioelectronics 2014 影响因子：5.437文章Ultrasensitive photoelectrochemical immunoassay of indole-3-acetic acid based on the MPA modified CdS/RGO nanocomposites decorated ITO electrode期刊：Environ. Sci. Technol 2013 影响因子：5.228文章:Graphene Oxide-Facilitated Reduction of Nitrobenzene in Sulfide-Containing Aqueous Solutions期刊：Journal of Materials Chemistry A 2013 影响因子：5.968文章:Nitrogen-doped mesoporous carbons originated from ionic liquids as electrode materials for supercapacitors南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China期刊：Nanoscale 2013 影响因子：5.914文章:Label-free Electrochemical Impedance Genosensor Based on 1-Aminopyrene/Graphene Hybrids 期刊：Chemistry - A European Journal 2013 影响因子：5.925文章:Three-Dimensional Hierarchical Architectures Constructed by Graphene/MoS2 Nanoflake Arrays and Their Rapid Charging/Discharging Properties as Lithium-Ion Battery Anodes期刊：Chemistry - A European Journal 2013 影响因子：5.925文章:Structural Engineering for High Energy and Voltage Output Supercapacitors期刊：Chemistry - A European Journal 2013 影响因子：5.925文章: Label-Free Detection of MicroRNA: Two-Step Signal Enhancement with a Hairpin-Probe-Based Graphene Fluorescence Switch and Isothermal Amplification大于等于4：期刊：Analytica Chimica Acta 2014 影响因子：4.378文章：In situ synthesis of ceria nanoparticles in the ordered mesoporous carbon as a novel electrochemical sensor for the determination of hydrazine.期刊：Journal of Power Sources 2014 影响因子：4.675文章：Three-dimensional macroporous anodes based on stainless steel fiber felt for high-performance microbial fuel cells.期刊：Journal of Power Sources 2014 影响因子：4.675文章：Sulfonated poly(ether ether ketone)/mesoporous silica hybrid membrane for high performance vanadium redox flow battery期刊：Journal of Power Sources 2012 影响因子：4.951文章: Carbon felt supported carbon nanotubes catalysts composite electrode for vanadium redox flow battery application期刊：Journal of Power Sources 2012 影响因子：4.951文章: A new method for fabrication of graphene/polyaniline nanocomplex modified microbial fuel cell anodes期刊：J. Phys. Chem. C 2012 影响因子：4.805文章: Alignment of Single-Walled Carbon Nanotubes with Ferroelectric Liquid Crystal期刊：Analytica Chimica Acta 2012 影响因子：4.555文章: Highly sensitive luminol electrochemiluminescence immunosensor based on ZnO nanoparticles and glucose oxidase decorated graphene for cancer biomarker detection期刊：Journal of Chromatography A 2012 影响因子：4.531文章: Simultaneous determination of 10 β2-agonists in swine urine using liquid chromatography–tandem mass spectrometry and multi-walled carbon nanotubes as a reversed dispersive solid phase extraction sorbent期刊：ACS Applied Materials & Interfaces 2012 影响因子：4.525文章: “Turn-on”Fluorescence Detection of Lead Ions Based on Accelerated Leaching of Gold Nanoparticles on the Surface of Graphene期刊：Chemistry-An Asian Journal 2012 影响因子：4.5南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China文章: Dispersion of Reduced Graphene Oxide in Multiple Solvents with an Imidazolium-Modified Hexa-peri-hexabenzocoronene期刊：Analyst 2012 影响因子：4.23文章: Glucose sensor based on an electrochemical reduced graphene oxide-poly(L-lysine) composite film modified GC electrode期刊：Analyst 2012 影响因子：4.23文章: A functional graphene oxide-ionic liquid composites/gold nanoparticles sensing platform for ultrasensitive electrochemical detection of Hg2+期刊：Analyst 2012 影响因子：4.23文章: Ultrasensitive colorimetric detection of heparin based on self-assembly of gold nanoparticles on graphene oxide期刊：PLOS ONE 2012 影响因子：4.092文章: Obstruction of Photoinduced Electron Transfer from Excited Porphyrin to Graphene Oxide: A Fluorescence Turn-On Sensing Platform for Iron (III) Ions期刊：Pharmaceutical Research 2012 影响因子：4.093文章: PEGylated Multi-Walled Carbon Nanotubes for Encapsulation and Sustained Release of Oxaliplatin期刊：Electrochemistry Communications 2014 影响因子： 4.425文章A Novel Electrochemical Immunosensor for Golgi Protein 73 Assay期刊：Journal of Power Sources 2014 影响因子： 4.675文章Mesoporous Li3V2(PO4)3@CMK-3 nanocomposite cathode material for lithium ion batteries期刊：Analytica Chimica Acta 2014 影响因子： 4.387文章Sensitive and selective electrochemical determination of quinoxaline-2-carboxylic acid based on bilayer of novel poly(pyrrole) functional composite using one-step electro-polymerization and molecularly imprinted poly(o-phenylenediamine)期刊：Journal of Membrane Science 2014 影响因子：4.093文章Poly(vinyl alcohol)–graphene oxide nanohybrid “pore-filling” membrane for pervaporation of toluene/n-heptane mixtures期刊：Journal of Power Sources 2014 影响因子： 4.675文章Non-aqueous hybrid supercapacitors fabricated with mesoporous TiO2 microspheres and activated carbon electrodes with superior performance期刊：Journal of Power Sources 2014 影响因子： 4.675文章Preparation of three-dimensional hybrid nanostructure-encapsulated sulfur cathode for high-rate lithium sulfur batteries期刊：Bioresource Technology 2013 影响因子： 4.75文章Selective production of chemicals from biomass pyrolysis over metal chlorides supported on zeolite期刊：Journal of Chromatography A 2013 影响因子： 4.612文章Simultaneous determination of six resorcylic acid lactones in feed using liquid chromatography–tandem mass spectrometry and multi-walled carbon nanotubes as a dispersive solid phase extraction sorbent南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China期刊：Journal of Power Sources 2013 影响因子： 4.675文章Reduced graphene oxide film as a shuttle-inhibiting interlayer in a lithium–sulfur battery期刊：The Journal of Physical Chemistry C 2013 影响因子： 4.814文章Electromagnetic Wave Absorption Properties of Reduced Graphene Oxide Modified by Maghemite Colloidal Nanoparticle Clusters期刊：Journal of Power Sources 2013 影响因子： 4.675文章Improving the performance of lithium–sulfur batteries by graphene coating期刊：Journal of Chromatography A 2013 影响因子：4.612文章Application of graphene as the stationary phase for open-tubular capillary electrochromatography 期刊：Journal of Power Sources 2013 影响因子：4.675文章Design, hydrothermal synthesis and electrochemical properties of porous birnessite-type manganese dioxide nanosheets on graphene as a hybrid material for supercapacitors期刊：Appl. Mater. Interfaces 2013 影响因子：4.525文章:One-Pot Environmentally Friendly Approach toward Highly Catalytically Active Bimetal-Nanoparticle-Graphene Hybrids期刊：Electrochemistry Communications 2013 影响因子：4.859文章:Fabrication of streptavidin functionalized silver nanoparticle decorated graphene and its application in disposable electrochemical sensor for immunoglobulin E期刊：ACS Appl. Mater. Interfaces 2013 影响因子：4.525文章:Facile Fabrication and Enhanced Photocatalytic Performance of Ag/AgCl/rGO Heterostructure Photocatalyst期刊：Analyst 2013 影响因子：4.23文章:One-pot green synthesis of graphene oxide/gold nanocomposites as SERS substrates for malachite green detection大于等于3：期刊：Sensors and Actuators B: Chemical影响因子：3.535文章：Facile preparation of highly water-stable and flexible PEDOT:PSS organic/inorganic composite materials and their application in electrochemical sensors.期刊：Electrochimica Acta影响因子：3.777文章：Inhibitory effect of silver nanomaterials on transmissible virus-induced host cell infections期刊：Microchimica Acta 2014 影响因子：3.434文章：Graphene oxide functionalized magnetic nanoparticles as adsorbents for removal of phthalate esters.期刊：Nanotechnology 2013 影响因子：3.979文章: Facile and straightforward synthesis of superparamagnetic reduced graphene oxide–Fe3O4 hybrid composite by a solvothermal reaction期刊：Sensors and Actuators B: Chemical 2012 影响因子：3.898文章: Sensitive DNA biosensor improved by 1,10-phenanthroline cobalt complex as indicator based on the electrode modified by gold nanoparticles and graphene期刊：Electrochimica Acta 2013 影响因子：3.832南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China文章: Electrochemical biosensor based on reduced graphene oxide modified electrode with Prussian blue and poly(toluidine blue O) coating期刊：Electrochimica Acta 2012 影响因子：3.832文章: High sensitive determination of theophylline based on gold nanoparticles/l-cysteine/Graphene/Nafion modified electrode期刊：Electrochimica Acta 2013 影响因子：3.832文章: Graphene oxide/nickel oxide modified glassy carbon electrode for supercapacitor and nonenzymatic glucose sensor期刊：Electrochimica Acta 2012 影响因子：3.832文章: Graphene oxide nanoribbon and polyhedral oligomeric silsesquioxane assembled composite frameworks for pre-concentrating and electrochemical sensing of 1-hydroxypyrene期刊：Bioelectrochemistry 2012 影响因子：3.759文章: Nonenzymatic amperometric determination of glucose by CuO nanocubes–graphene nanocomposite modified electrode期刊：Chemical Engineering Journal 2012 影响因子：3.461文章: Self-assembly of graphene oxide and polyelectrolyte complex nanohybrid membranes for nanofiltration and pervaporation期刊：Fuel 2012 影响因子：3.248文章: Experimental study on bio-oil upgrading over catalyst in supercritical ethanol期刊：RSC Advances 2013 2011年创刊预计影响因子：大于3.0文章: Sandwich nanocomposites of polyaniline embedded between graphene layers and multi-walled carbon nanotubes for cycle-stable electrode materials of organic supercapacitors期刊：RSC Advances 2012 2011年新刊，预计影响因子：大于3.0文章: Electrochemically-driven and dynamic enhancement of drug metabolism via cytochrome P450 microsomes on colloidal gold/graphene nanocomposites期刊：Electrochimica Acta 2014 影响因子： 3.777文章(4-Ferrocenylethyne) Phenylamine Functionalized Graphene Oxide Modified Electrode for Sensitive Nitrite Sensing期刊：Sensors and Actuators B: Chemical 2014 影响因子： 3.535文章Simultaneous determination of dihydroxybenzene isomers based on graphene-graphene oxide nanocomposite modified glassy carbon electrode期刊：Sensors and Actuators B: Chemical 2014 影响因子： 3.535文章Sensitive electrochemiluminescence sensor based on ordered mesoporous carbon composite film for dopamine期刊：Talanta 2014 影响因子： 3.498文章Square wave anodic stripping voltammetric determination of Cd2+ and Pb2+ at bismuth-film electrode modified with electroreduced graphene oxide-supported thiolated thionine期刊：Sensors and Actuators B: Chemical 2014 影响因子： 3.535文章A multiple-promoted silver enhancement strategy in electrochemical detection of target virus期刊：Nanotechnology 2014 影响因子： 3.842南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China文章Ag–graphene hybrid conductive ink for writing electronics期刊：Analyst 2014 影响因子： 3.969文章Capillary electrophoresis-based immobilized enzyme reactor using graphene oxide as support via layer by layer electrostatic assembly期刊：Microchimica Acta 2014 影响因子： 3.434文章Fluorescent aptasensor for the determination of Salmonella typhimurium based on a graphene oxide platform期刊：Talanta 2014 影响因子：3.498文章Tannic acid functionalized N-doped graphene modified glassy carbon electrode for the determination of bisphenol A in food package期刊：Composites Science and Technology 2013 影响因子： 3.328文章Fabrication of graphene/polylactide nanocomposites with improved properties期刊：Microporous and Mesoporous Materials 2014 影响因子： 3.365文章Synthesis, characterization and CO2 capture of mesoporous SBA-15 adsorbents functionalized with melamine-based and acrylate-based amine dendrimers期刊：Analyst 2013 影响因子： 3.969文章Graphene based electrochemical biosensor for label-free measuring the activity and inhibition of protein tyrosine kinase期刊：Electrochimica Acta 2013 影响因子： 3.777文章Preparation and charaterization of Pt/functionalized graphene and its electrocatalysis for methanol oxidation期刊：Plos One 2013 影响因子： 3.73文章Synergistic Removal of Pb(II), Cd(II) and Humic Acid by Fe3O4@Mesoporous Silica-Graphene Oxide Composites期刊：Electrochimica Acta 2013 影响因子： 3.777文章Electrocatalytic oxidation and detection of N-acetylcysteine based on magnetite/reduced graphene oxide composite-modified glassy carbon electrode期刊：Catalysis Science & Technology 2013 影响因子： 3.753文章The role of reducing agent in perylene tetracarboxylic acid coating on graphene sheets enhances Pd nanoparticles-electrocalytic ethanol oxidation期刊：Acta Materialia 2013 影响因子： 3.941文章Nanoconfinement significantly improves the thermodynamics and kinetics of co-infiltrated 2LiBH4–LiAlH4 composites: Stable reversibility of hydrogen absorption/resorption期刊：Microchimica Acta 2013 影响因子：3.434文章Highly sensitive and selective voltammetric detection of mercury(II) using an ITO electrode modified with 5-methyl-2-thiouracil, graphene oxide and gold nanoparticles期刊：Composites Science and Technology 2013 影响因子：3.328文章Porous graphene sandwich/poly(vinylidene fluoride) composites with high dielectric properties 期刊：Electrochimica Acta 2013 影响因子： 3.777文章Cu2O/NiOx/graphene oxide modified glassy carbon electrode for the enhanced electrochemical oxidation of reduced glutathione and nonenzyme glucose sensor南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China期刊：Electrochimica Acta 2013 影响因子： 3.777文章Direct electrodeposion of reduced graphene oxide and dendritic copper nanoclusters on glassy carbon electrode for electrochemical detection of nitrite期刊：Analyst 2013 影响因子： 3.969文章Realization of on-tissue protein identification by highly efficient in situ digestion with graphene-immobilized trypsin for MALDI imaging analysis期刊：Food Chemistry 2014 影响因子：3.334文章Electrochemical determination of toxic ractopamine at an ordered mesoporous carbon modified electrode期刊：Talanta 2013 影响因子：3.498文章Simultaneous Determination of Dopamine and Uric Acid Using Layer-by-Layer Graphene and Chitosan Assembled Multilayer Films期刊：Electrochimica Acta 2013 影响因子：3.777文章Electrochemically Cathodic Exfoliation of Graphene Sheets in Room Temperature Ionic Liquids N-Butyl, methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide and Their Electrochemical Properties 期刊：Journal of Applied Physics 2013 影响因子：2.21文章An experimental investigation on fluidic behaviors in a two-dimensional nanoenvironment期刊：Journal of Molecular Catalysis A: Chemical 2013 影响因子：3.187文章Enhancing the photocatalytic activity of lead molybdate by modifying with fullerene期刊：Physical Chemistry Chemical Physics 2013 影响因子：3.829文章Improving the antifouling property of polysulfone ultrafiltration membrane by incorporation of isocyanate-treated graphene oxide期刊：Sensors and Actuators B: Chemical 2013 影响因子：3.535文章Electrochemical modification of graphene oxide bearing different types of oxygen functional species for the electro-catalytic oxidation of reduced glutathione期刊：Sensors and Actuators B: Chemical 2013 影响因子：3.535文章A novel graphene oxide-based fluorescence assay for RNA endonuclease activity of mammalian Argonaute2 protein期刊：Sensors and Actuators B: Chemical 2013 影响因子：3.535文章Enhanced room temperature sensing of Co3O4-intercalated reduced graphene oxide based gas sensors期刊：Talanta 2013 影响因子：3.498文章Graphene matrix for signal enhancement in ambient plasma assisted laser desorption ionization mass spectrometry期刊：Sensors and Actuators B: Chemical 2013影响因子：3.535文章Electrodeposition of electroreduced graphene oxide-Au nanoparticles composite film at glassy carbon electrode for anodic stripping voltammetric analysis of trace arsenic(III)期刊：Physical Chemistry Chemical Physics 2013 影响因子：3.829文章Enhanced reverse saturable absorption in graphene/Ag2S organic glasses期刊：Electrochimica Acta 2013 影响因子：3.777南京先丰纳米材料科技有限公司Nanjing XFNANO Materials Tech Co.,Ltd 地址：南京市鼓楼区南京大学国家大学科技园Add：Nanjing Jiangsu Province China文章Electrochemical immunoassay platform for high sensitivity detection of indole-3-acetic acid期刊：Analyst 2013 影响因子：3.969文章Aptamer-linked biosensor for thrombin based on AuNPs/Thionine-graphene nanocomposite期刊：Journal of Colloid and Interface Science 2013 影响因子：3.172文章Green Synthesis and Photo-catalytic Performances for ZnO-Reduced Graphene Oxide Nanocomposites期刊：Electrochimica Acta 2013 影响因子：3.832文章: Insight into effects of graphene in Li4Ti5O12/carbon composite with high rate capability as anode materials for lithium ion batteries期刊：Dalton Transactions 2013 影响因子：3.838文章:Remarkable improvements in the stability and thermal conductivity of graphite/ethylene glycol nanofluids caused by a graphene oxide percolation structure期刊：Talanta 2013 影响因子：3.794文章:Selective and sensitive determination of uric acid in the presence of ascorbic acid and dopamine by PDDA functionalized graphene/graphite composite electrode期刊：ELECTROPHORESIS 2013 影响因子：3.303文章:Graphene oxide and reduced graphene oxide as novel stationary phases via electrostatic assembly for open-tubular capillary electrochromatography期刊：Sensors and Actuators B 2013 影响因子：3.898文章:A reduced graphene oxide based biosensor for high-sensitive detection of 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Supercapacitor Electrodes Based on Layered Tungsten Disulfide-Reduced Graphene Oxide Hybrids Synthes
11427
/10.1021/am403663f | ACS Appl. Mater. Interfaces 2013, 5, 11427−11433
Satyajit Ratha and Chandra Sekhar Rout*
School of Basic Sciences, Indian Institute of Technolondia
S Supporting Information *
Research Article
Supercapacitor Electrodes Based on Layered Tungsten DisulfideReduced Graphene Oxide Hybrids Synthesized by a Facile Hydrothermal Method
© 2013 American Chemical Society
oxides,26−31 metal chalcogenides,32−38 and their composites39 have shown to be efficient and promising materials for high performance supercapacitor electrodes due to their high surface area and large in-plane conductivity. Metal sulfides are known to be electrochemically active materials for supercapacitor applications, but to date very few metal sulfides have been employed to fabricate supercapacitor electrodes.32−37 Because of their synergic advantages of high conductivity and high surface area, VS2 nanosheets have been employed to fabricate in plane supercapacitor electrodes.32 Ajayan and co-workers reported fabrication of micro-supercapacitors based on 2D MoS2 films prepared by a low-cost spray painting technique and subsequent laser patterning.33 Supercapacitor electrodes based on CoS2 and CoS2/graphene hybrids have been shown as promising materials for energy storage.34,35 Similarly, NiS sheets have been demonstrated as an electrode material for supercapacitor because of their large surface area and enhanced structural stability.37,38 Hence, the success of applying a
基于近场动力学的FRP层压板建模与分析
申请上海交通大学硕士学位论文基于近场动力学的FRP层压板建模与分析学校：上海交通大学院系：航空航天学院班级：B1041391学号：**********硕士生：胡祎乐专业：飞行器设计*师：**上海交通大学航空航天学院二〇一三年一月A Dissertation Submitted to Shanghai Jiao Tong University forMaster's DegreePERIDYNAMIC MODELING AND ANALYSIS OF FRPLAMINATESAuthor: HU YileSpecialty: Flight Vehicle DesignAdvisor: YU YinSchool of Aeronautics and AstronauticsShanghai Jiao Tong UniversityShanghai, P.R. ChinaJanuary 2013基于近场动力学的FRP层压板建模与分析摘要纤维增强复合材料（Fiber Reinforced Plastics，简称FRP）在渐进破坏过程中涉及到诸多不连续问题，例如损伤、裂纹、分层、断裂和穿透等，而基于空间位移场偏微分方程的传统连续介质力学理论在对这些不连续问题求解时往往会遇到困难。
近期一种新兴的固体力学理论——近场动力学理论（Peridynamic Theory），采用积分形式描述构型的基本运动方程，可以避免对位移场求导，特别适合于求解不连续问题。
本文首先对近场动力学的国内外研究现状，基本理论以及相应的数值方法进行了简要介绍。
随后，研究提出了一种基于近场动力学理论的纤维增强复合材料层压板的渐进损伤分析方法。
根据近场动力学理论，物体参考构型中各节点与有限距离内的其余节点之间通过―键‖产生相互作用。
本文在―键‖的定义中结合了经典层压板理论中的偏轴模量，使得―键‖能反映不同夹角铺层的性能，从而改进了近场动力学分析中对复合材料各向异性特性的描述。
Ni－Fe LDH的电沉积制备及其电催化氧析出性能
Ni－Fe LDH的电沉积制备及其电催化氧析出性能徐梦莹;孟玲袆;王雅静;刘洪涛【摘要】氧析出反应（ OER）是阳极电解水的关键步骤。
提出了一种简单可控的一步电沉积制备Ni－Fe LDH的方法，并成功用于电催化OER反应。
结果表明，在－1�1 V条件下，采用1∶1镍铁摩尔比，沉积液总浓度为0�12 M时沉积300 s所得Ni－Fe LDH薄膜催化剂具有高的OER催化活性（在10 mA／cm2电流密度下的过电位为220 mV）、快的反应动力学（塔菲尔斜率为44�9 mV／dec）和优良的催化稳定性（持续极化10 h仅衰减2�5％）。
%Oxygen evolution reaction ( OER) is the key step for water splitting at anode. The paper presents a simple and controllable method for one-step synthesis of nickel-iron layered double hydroxide ( Ni-Fe LDH ) as a potential OER electrocatalyst. It is found that the Ni-Fe LDH deposited under the optimal conditions ( deposition time: 300 s; deposition potential: -1.1V;Ni2++Fe3+total concentration:0.12 M;Ni/Fe ratio:1∶1) demonstrateshigh catalytic activity ( overpotential 220 mV at 10 mA/cm) , fast reaction dynamics ( Tafel slope 44.9 mV/dec) , and excellent stability ( retaining 97.5% after 10 h) toward OER reaction.【期刊名称】《龙岩学院学报》【年(卷),期】2016(034)005【总页数】5页(P24-28)【关键词】电沉积;层状双金属氢氧化物;电催化;氧析出反应【作者】徐梦莹;孟玲袆;王雅静;刘洪涛【作者单位】中南大学湖南长沙 410083;中南大学湖南长沙 410083;中南大学湖南长沙 410083;中南大学湖南长沙 410083【正文语种】中文【中图分类】O646随着传统化石燃料的大量消耗，能源紧缺的问题愈发突出，寻找可替代的清洁能源成为科学家们研究的热点课题之一［1］。
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Analysisandoptimaldesignoflayeredcompositeswithhighstiffnessandhighdamping
JulienMeauda,⇑,TrishaSainb,GregoryM.Hulberta,AnthonyM.Waasa,baDepartmentofMechanicalEngineering,UniversityofMichigan,AnnArbor,UnitedStates
bDepartmentofAerospaceEngineering,UniversityofMichigan,AnnArbor,UnitedStates
articleinfoArticlehistory:Received20October2012Receivedinrevisedform27December2012Availableonline24January2013
Keywords:CompositematerialsOptimizationViscoelasticDamping
abstractInthispaperweinvestigatethedesignofcompositematerialswithsimultaneouslyhighstiffnessandhighdamping.Weconsiderlayeredcompositematerialswithparallelplanelayersmadeofastiffconstit-uentandalossypolymer.Weanalyzetheresponseofthesecompositestoadynamicloadwithanarbi-trarydirection.Usingtheviscoelasticcorrespondenceprincipleandlinearfrequencydomainviscoelasticmodels,wederiveanexpressionfortheeffectivecomplexmodulusoflayeredcompositesofinfinitesizeatinfinitesimalstrains.Thedependenceoftheeffectivedynamicmodulusandlossfactoronthegeomet-ricalparametersandonthetensileandbulklossfactorsofthelossyconstituentisanalyzed.Moreoverwedeterminethemagnitudeofthestrainsinthelossyconstituentanddemonstratethatthecombinationofhighstiffnessandhighdampingofthesecompositesisduetothehighnormaland/orshearstrainsinthelossymaterial.Weusenonlinearconstrainedoptimizationtodesignlayeredcompositeswithsimulta-neouslyhighstiffnessandhighdampingwhileconstrainingthestrainsinthepolymer.Todeterminetherangeofvalidityofthelinearviscoelasticmodel,simulationsusingfinitedeformationsmodelsarecomparedtothetheoreticalresults.Finally,wecomputetheeffectivepropertiesofcompositesoffinitesizeusingfiniteelementmethodsanddeterminetheminimumsizerequiredtoapproachtheformulaederivedforcompositesofinfinitesize.Ó2013ElsevierLtd.Allrightsreserved.
1.IntroductionTheanalysisanddesignofmultifunctionalmaterialsisatopicofactiveresearch(Cadmanetal.,2012).Thedesignofcompositematerialswithcompetingattributeshavebeenexploredusingmainlymultiobjectivetopologyoptimizationtechniques.Examplesofcompositepropertiesthatwereoptimizedincludestiffnessandpermeability(GuestandPrevost,2006),transportofheatandelec-tricity(Torquatoetal.,2002),andstiffnessandresistancetoheat(deKruijfetal.,2007).Inthisworkwederiveananalyticalmodelandusenumericaloptimizationtodesignaclassofcompositematerialswithsimultaneouslyhighstiffnessandhighdamping.AsdiscussedinLakes(2009),materialswithbothhighdampingandstiffnesswouldbeusefulinstructuralapplications.However,materialswithhighdamping(suchashighlosselastomers)tendtobesoft(Lakes,2009;Ashby,1989).Viscoelasticcompositeswithastiffconstituentandalossy,softconstituentmightachieveacombinationofhighstiffnessandhighdamping.Thedesignofcompositetopologieswithhighstiffnessand/ordampinghavebeeninvestigatedbeforeusinganalyticalandcomputationalmeth-ods.Lakesandcoworkersinvestigatedvarioustopologieswithhigh
stiffnessanddamping(ChenandLakes,1993;Kimetal.,2002;Lakes,2002).ChenandLakesderivedformulaefortheReussandVoigttopologiesandcompositeswithsphericalparticulateinclu-sions(ChenandLakes,1993).Kimetal.(2002)usedcomputationalhomogenizationtodeterminetheeffectivedynamicpropertiesofSiC–InSnparticulatereinforcedcomposites.Lakes(2002)showedthathierarchicalparticulatemorphologiescanachievehighstiff-nessanddamping.Othertheoreticalstudiesincludethedesignofcompositeswithoptimaldampingand/orstiffnessusingtopologyoptimizationbyYietal.(2000).Pateletal.usedthefiniteelementmethodtodesignviscoelasticcompositematerialswithhighdampingoverawidefrequencyrange(Pateletal.,2007).PrasadandDiazdesignedviscoelasticcompositesthatincludeanegativestiffnessconstituentandwithatargeteffectiveviscoelastictensor(PrasadandDiaz,2009)usingtopologyoptimizationandinversehomogenization.Inarecentstudyweinvestigatedusingfiniteele-mentmethodstheeffectivestiffnessanddampingofcompositeswithwavylayers(Sainetal.,inpress).Inthispaperwefocusonlayeredcompositeswithparallelplanelayersoftwoconstituents.Layeredcompositesareofinterestbe-causetheyaresimpletomanufacture.NeglectingthePoissonef-fects,ChenandLakes(1993)derivedformulaefortheeffectivedynamicpropertiesoflayeredcompositesloadedinthelayerdirection(Voigttopology)andperpendiculartothelayerdirection
0020-7683/$-seefrontmatterÓ2013ElsevierLtd.Allrightsreserved.http://dx.doi.org/10.1016/j.ijsolstr.2013.01.014
⇑Correspondingauthor.Tel.:+17342721069.
E-mailaddress:jmeaud@umich.edu(J.Meaud).
InternationalJournalofSolidsandStructures50(2013)1342–1353ContentslistsavailableatSciVerseScienceDirectInternationalJournalofSolidsandStructures