Instrumented Indentation Investigation on the Viscoelastic Properties of Porcine Cartilage

Articular cartilage lubricates the contact surfaces in human joints and provides a shock-absorbing effect which protects the joint under dynamic loading. However, this shock-absorbing effect is gradually reduced as the result of normal wear, tear and aging-related cartilage loss. Thus, with the increasing average human life expectancy, the issue of joint health has attracted significant interest in recent decades. In developing new materials for the repair or regeneration of damaged articular cartilage, it is essential that the difference in the mechanical properties of healthy and damaged cartilages is well-understood. In the present study, the hardness and Young＇s modulus of damaged and healthy porcine articular cartilage samples are evaluated via a quasi-static nanoindentation technique. A dynamic mechanical analysis method is then applied to determine the viscoelastic properties of the two samples. The results presented in this study provide a useful insight into the mechanical properties of articular cartilage at the mesoscale, and therefore fill an important gap in the literature.     

Characterization of a micro-roughened TiO2/ZrO2 coating： mechanical properties and HBMSC responses in vitro

Previous studies have shown phase to bioceramics can that using ZrO2 as a second significantly increase the bonding strength of plasma-sprayed composite material. In the present study, micro-roughened titanium dioxide/ zirconia （TiO2/ZrO2） （30 wt% ZrO2） coating and TiO2 coating were plasma-sprayed onto Ti plates. The microstructural characteristics and mechanical properties of both coatings were investigated. Furthermore, the biological behavior and osteogenic differentiation of human bone marrow mesenchymal stem cells （HBMSCs） on both TiO2/ZrO2 and TiO2 coatings were compared. The results indicated that the shear bond strength and microhardness of TiO2/ZrO2 coating were statistically higher than those of TiO2 coating. Scanning electron microscope observation revealed that more irregularly shaped protuberances and denser pores were formed on the surface of TiO2/ ZrO2 coating compared with those of TiO2 coating. Further comparative analysis of HBMSC proliferation and osteogenic differentiation on both coatings showed that significantly higher cellular alkaline phosphatase activity and expression levels of Runx2 and Osterix at day 10 after osteogenic culture were found on TiO2/ZrO2 coating compared with TiO2 coating, while no statistically significant difference in cell proliferation and extracellular calcium deposition was observed. The present study suggests that TiO2/ZrO2 coating may be favorable for dental implant applications.     

利用湿强度测定仪测定植物细胞壁的机械性能

UsingWetStrengthTestertoMeasuretheMechanicalParametersofPlantCellWallHUANGXu－Ming（CollegeofBiotechnology，SouthChinaAgriculturalUniversity，Guangzhou510642）HUANGHui－Bai（DepartmentofHorticulture，SouthChinaAgriculturalUniversity，Guangzhou510642）细胞壁的机械状态与细胞的膨大生长有密切的关系。～些生理现象，如生理裂果现象，与细胞壁的机械性能密切相关。研究细胞壁机械性能的方法有多种。如利用压力室P－V曲线法，可以推算出细胞壁的弹性模量则asticrllfxlules）［'j；一些特大的细胞，如丽…     

Structural-Nanomechanical Property Correlation of Shallow Water Shrimp （Pandalus platyceros） Exoskeleton at Elevated Temperature

This investigation reports the nanomechanical properties of shallow water shrimp exoskeleton at temperatures ranging from 30 ℃ to 80 ℃ measured using nanoindentation experiments. Scanning Electron Microscopy （SEM） measurements suggest that the shrimp exoskeleton has the Bouligand structure in its layers, a key characteristic of the crustaceans. The thickness of the layers and packing density are found to be different from that of lobsters and crabs reported earlier in the literature. Mechanical properties at high temperatures are determined using micro materials nanoindentation test set up combined with the hot stage. The properties measured during nanoindentation test are corrected for the creep and thermal drift during the experiments. The reduced modulus values are found to be around 28 GPa at 30 ℃ that reduces to approximately 24 GPa at 80 ℃. The hardness values also decrease from 1.6 GPa at 30 ℃ to around 1.2 GPa at 80 ℃. The indentation size effect is found to be absent at all temperatures. Creep mechanisms of polymers like materials and its temperature dependence are discussed to give more insight into the deformation mechanism.     

羊毛中高分子交联度与其机械性能的关系

文中列举蚕丝聚合物交联度与其机械性能的关系,提供试验成果。     

乳丝的加工、性能及其应用

乳丝学名为聚乳酸纤维,是一种可生物降解的新型绿色纤维,目前制备方法主要有熔融纺丝、溶液纺丝和静电纺丝等3种方法。作为一种新型的可降解纤维材料,其环保性、吸湿性、透气性、生物相容性以及优良的力学性能决定了其在生物医用、织物面料、非织造材料(如一次性卫生用品、过滤材料等)等很多方面都将得到广泛应用。     

PLGA-脱细胞猪皮的性质研究

目的:猪皮来源的细胞外基质(ECM)被广泛应用于组织工程材料的研制中,由于使用目的的不同,常需要和其它组织工程原料进行复合使用.本研究将PLGA和脱细胞猪皮进行复合,在体外考察此复合体系的力学性质和三维结构,探讨其作为组织工程支架的可行性.方法:(1)采用高压渗透法将PLGA和脱细胞猪皮制备成供检试件.(2)以扫描电镜观察其内部的三维结构.(3)用拉伸实验机测试其拉伸力学特性.结果:(1)力学测试显示,其断裂强度为1.32MPa,断裂伸长率约为132%,弹性模量为1.6×106Pa.(2)扫描电镜显示PLGA渗入到脱细胞猪皮的空隙中而相互融合,形成了蜂窝状结构.结论:本研究所构建的PLGA-脱细胞猪皮复合物具有适宜的机械性能,其蜂窝状结构为其作为细胞载体提供了良好的空间结构,是一种具有良好应用前景的组织工程支架.     

4种常见蜘蛛蛛丝光学显微镜观察及机械性能的测定

对4种常见蜘蛛大腹园蛛Araneus ventricosus、迷宫漏斗蛛Agelena labyrinthica、草间钻头蛛Hylyphantes graminicola和棒络新妇Nephila clavata蛛丝的物理特性和机械性能进行了初步研究.结果 表明:捕丝是由2根核心丝构成,4种蛛丝呈现不同的颜色;4种蜘蛛蛛丝的密度略有不同,棒络新妇的蛛丝密度最大,草间钻头蛛的蛛丝密度最小;蛛丝中棒络新妇的断裂伸长率和断裂强度都最大,分别为47.3%和852.6 Nmm-2,草间钻头蛛蛛丝的断裂伸长率和断裂强度都最小,分别为32.1%和652.3 Nmm-2.与其它物理化学材料相比,蛛丝具有优异的综合力学性能,生物学特性与生物学功能具有高度一致性.     

AFM对3T3-L1前脂细胞及其骨架的可视化研究

目的:为脂肪细胞分化提供数据,加深对3T3-L1细胞分化机制的了解.方法:应用AFM对3T3-L1前脂细胞的形貌、超微结构、机械性能和细胞骨架进行了可视化研究.结果:3T3-L1细胞舒展,伪足丰富,膜表面有大小不一的斑块和突起.通过统计分析得出3T3-L1细胞的高低差,均方根粗糙度、平均粗糙度和平均高度分别为622.3nm、77.34nm、55.80nm、393.1nm;AFM针尖与细胞膜表面的相对粘弹力为95.10±19.41pN,平均硬度为2.36±0.39mN/m,杨氏模量为4.85±0.99kPa.AFM对3T3-L1细胞骨架成像,观察到骨架南排列整齐的大纤维束和细小的微纤维以及颗粒状蛋白组成,形成网络结构.结论:细胞形貌结合细胞的机械性能可知3T3-L1细胞生长状态良好,细胞的移动迁移能力强.