立交桥施工中WDJ钢管脚手架的受力分析

在立交桥、高架桥和人行天桥的建设过程中，作为施工模板支撑的脚手架搭设常遇到承载力不足，脚手架失稳等问题，根据现浇钢筋混凝土立交桥施工过程中此类脚手架的搭设情况，以实际工程中常用的WDJ碗扣式钢管脚手架为对象，运用有限元程序ANSYS进行分析，着重研究桥梁腹板位置变化、桥梁高度变化对脚手架受力的影响，同时对风荷载作用下的脚手架和隔梁位置下的脚手架进行受力分析，提出通常情况下WDJ碗扣式钢管脚手架的选用形式，为脚手架工程的安全施工提供一定的帮助。     

丝素蛋白在组织工程中的应用

丝素蛋白作为一种具有优良生物相容性的天然高分子材料在生物医用领域有着广泛的应用，着重阐述了丝素蛋白在组织工程领域中应用研究的最新进展。     

胶原支架材料的制备与表征

分别采用真空高温脱水和化学交联剂1-乙基-3-(3-二甲基氨基丙基)-碳化二亚胺处理经冷冻干燥后的胶原海绵材料,制备组织工程支架,讨论反应条件对胶原性能的影响,测定胶原支架的力学强度和降解特性.结果发现,不同的处理方法都能保持胶原海绵的三维多孔结构,孔隙率可达到90%;真空高温脱水获得的胶原海绵材料力学强度较小,但断裂伸长率略大;碳化二亚胺交联胶原海绵材料力学强度相对较高,抗张强度为380 kPa左右.胶原海绵交联后,降解速率显著小于未经交联的胶原材料.细胞培养试验表明成纤维细胞可以在支架材料上正常生长.两种交联方法处理胶原海绵,其细胞生长行为差异无显著性,适合于作为组织工程支架.     

韧带-骨支架仿生界面设计与制造方法

针对当前软质韧带支架与硬质骨组织通过机械固定进行韧带修复存在的应力集中与疲劳断裂问题,提出了具有仿生界面的韧带-骨支架设计与制造方法。研究了自然韧带-骨界面的微观结构,通过工程简化设计了具有仿生界面的韧带-骨复合支架,提出了韧带-骨支架仿生界面的分层制造方法,从材料、力学及微观结构方面对所制备的韧带-骨支架仿生界面进行了分析评价。结果表明,所提出的分层制造方法可在软质韧带纤维支架与硬质陶瓷骨支架之间精确制造出所设计的仿生界面,其在材料成分、力学性能及微观结构上呈现分区变化特性。后期通过骨支架与自体骨融合生长以及仿生界面的多组织再生,有望实现韧带纤维支架与自体骨骨道的生理愈合及可靠固定,从而为临床韧带修复提供一种新思路。     

天然丝素制备三维多孔支架

研究盐沥滤法制备三维多孔丝素支架,在丝素多孔支架上培养人成骨肉瘤细胞、成纤维细胞及肝细胞.研究材料的细胞相容性,发现多种动物细胞在盐沥滤法所制备的丝素多孔支架材料上能够很好地黏附和增殖.通过调整丝素水溶液的浓度、溶解丝素溶剂体系、NaCl添加量和NaCl粒径,制备出结构和性质可以调控的三维支架.该结果为丝素多孔支架材料的制备提供了新的研究思路和方法.     

Effect of degradation of PLGA and PLGA/β-TCP scaffolds on the growth of osteoblasts

Osteoblasts were cultured on porous scaffolds of poly(L-lactide-co-glycolide) (PLGA) and PLGA/β-tricalcium phosphate (β-TCP) to evaluate their cytocompatibility. The proliferation of the cells on both scaffolds was examined before and after in vitro degradation for 4, 8 and 12 weeks under static (shaking water bath) and dynamic (cyclic loading) conditions. Results indicate that porous PLGA and PLGA/β-TCP scaffolds have good biocompatibility and can be used as effective templates for guiding the growth of osteoblasts. The degradation of the scaffolds affects the proliferation of osteoblasts and the cell viability decreased with the degradation time.     

肝组织工程支架的仿生设计与有限元分析

为了解决细胞在细胞支架复合培养中难以植入的问题,提出了一种卷裹型支架.将平面多孔支架采用卷裹的方式成型,使细胞在整个支架内部形成螺旋状三维分布,支架表面的管道结构可使培养液在支架内部渗透,从而提高物质交换效率.提出了一种具有仿生参数的流道设计方案,从肝脏血管铸型中提取血管的形状数据,作为仿生学依据进行流道设计,具体为树状多层分支结构.用此流道结构仿生了动脉、静脉的血液循环功能,并利用多孔材料仿生了毛细血管的渗透功能.建立了不同形状参数的流场分析模型,进行流体与多孔材料的渗流分析.结果表明,仿生设计方案的流场分布最为均匀,且平均流速较高,间接表明营养物质的输送效率最高.该支架能够使细胞呈三维分布,并扩大培养液在支架内的有效分布范围,更好地维持细胞的存活、增殖和迁移,为向组织化方向发展奠定了一定的基础.     

3D Nanocomposite Hydrogel Scaffolds Fabricated by Rapid Prototyping for Bone Tissue Engineering

Colloidal gels made of oppositely charged nanoparticles are a novel class of hydrogels and can exhibit pseudoplastic behavior which will enable them to mold easily into specific shapes. These moldable gels can be used as building blocks to self-assemble into integral scaffolds from bottom to up through electrostatic forces. However, they are too weak to maintain scaffold morphology just depending on interparticle interactions such as Van der Waals attraction and electrostatic forces especially for bone tissue engineering. In this study, oppositely charged gelatin nanoparticles were firstly prepared by two-step desolvation method, followed by the mixture with water to form colloid gels. To solve the problem of weak mechanical performance of colloid gels, gelatin macromolecules were introduced into the prepared gels to form blend gels. The blend gels can be easily processed into three-dimensional （3D） porous scaffolds via motor assisted microsyringe （MAM） system, a nozzle-based rapid prototyping technology, under mild conditions. After fabrication the scaffolds were erosslinked by glutaraldehyde （ GA, 25 % solution in water by weight）, then the crosslinked gelatin macromolecules network could form to improve the mechanical properties of colloid gels. The average particle size and zeta potential of gdatin nanoparticles were measured by Nano- ZS instrument. The morphology and microstructures of scaffolds were characterized by macroscopic images. The mechanical properties of the scaffolds were studied by a universal material testing machine.     

异型卡式脚手架防坠落装置的设计与强度校验

针对现有的附着式升降脚手架防坠落装置存在的不足,根据脚手架的结构和安装位置,设计了一种基于速度控制的制动机构——异型卡式防坠落装置。该防坠落装置主要构件是异型卡子和多爪转子,异型卡子具有独特的形状结构。当脚手架慢速提升和下降时,多爪转子作逆时针或顺时针转动,而异型卡子仅小幅摆动;当脚手架急速坠落时,多爪转子与异型卡子互相卡死,防止架体坠落。为验证防坠落装置在升降脚手架坠落时的安全性能,对脚手架主要构件进行了有限元分析与强度校验,结果证明所设计的防坠装置主要构件的强度满足施工需要。     

Fabrication and characterization of a PAM modified PHBV/BG scaffold

In order to improve the bioactivity and mechanical strength of the scaffold used in bone repair simultaneously, a novel porous PAM-poly （β-hydroxybutyrate-co-β-hydroxyvalerate） （PHBV）/bioactive glass （BG） scaffold was prepared by photo-initiated polymerization. PAM was used to improve the hydrophilicity of PHBV matrix while the BG particles were added to increase the bioactivity and strength of the matrix synchronously. The grafted amide group and Si-O moieties from acrylamide and the added BG were confirmed by Fourier Transform Infrared Spectrometry （FTIR）. The micromorphology of the scaffolds before and after grafting was observed by scanning electron microscopy （SEM）. The resulting images demonstrate that the PAM-PHBV/BG scaffold has a well connected pore structure and appropriate pore size which may be convenient for cells to grow and discharge metabolites. The specific gravity method was used to evaluate the pore property of the scaffold and the result shows that the scaffold has an average porosity up to 82.0%. Mercury intrusion porosimetry （MIP） indicated that the pores of PAM-PHBV/BG scaffold were mainly distributed between 75 and 150 μm. The compressive strength test was adopted to evaluate the mechanical property of the scaffold. The result shows that the PAM-PHBV/BG scaffold has a relatively high compressive strength （0.91 MPa） when compared with the pure PHBV scaffold. Besides, the properties of the pure PHBV scaffold, PHBV/BG scaffold were also evaluated. The newly prepared PAM-PHBV/BG scaffold may be worthy of further studying as a bone repair material.