基于知识的人工骨三维结构仿生设计研究

针对目前人工骨设计中产生的生物活性差、设计周期长、植入人体内出现排异现象等问题,提出了一种基于知识的人工骨三维结构仿生设计方法;结合人体的知识模型,分成人工骨外部三维重建和内部微观结构仿生设计两部分,可以设计出具有内部仿生微观结构和外部与实际骨形状相似的人工骨。     

基于CAD和SL的人工骨微管支架的制备研究

研究一种基于光固化快速成形技术的人工骨支架制备方法。设计空间结构的人工骨支架负型,利用立体光固化快速成形系统制造人工骨支架负型树脂原型,在人工骨支架负型树脂原型中填充β-磷酸三钙,通过热分解的方法去除SL原型,获得生物活性人工骨支架。研究了烧结与去除原型的方法,测得人工骨支架表面粗糙度分别是Ra=3.69,有利于细胞的黏附。进行体外细胞培养研究,发现成骨细胞能够在这人工骨支架上黏附生长,并向微管内生长,具有良好的生物学特性。     

基于逆向工程和UG二次开发的人工骨组织结构造型仿真

为减少传统的自体移植修复方法所带来的并发症与附加损伤,提出可以制备改善人体病变组织的结构、功能的生物活性代替物的模型,其是人工假体修复技术的关键。基于逆向工程和UG二次开发,利用Mimics医学图像软件对骨骼外形进行逆向建模,导入UG中实体处理,划分网格并简化分析,利用程序语言计算得到多孔人工骨组织结构造型模型。以该模型为模具,利用快速原型理论,可以在快速原型机中制作出生物活性的人工假体。     

PLLA/CPC复合支架增强结构设计及制备

为制备用于负重部位骨缺损修复的人工植入体,提出了一种复合增强结构人工骨设计及制备方案,该方案采用聚左旋乳酸支架(PLLA)为增强结构,以自凝固磷酸钙骨水泥(CPC)为复合填充材料,制备了复合增强结构人工骨。研究了PLLA的棒材力学性能、支架设计和制作及其不同增强结构形式对人工骨力学性能的影响。力学试验结果表明,所制作的人工骨有效提高了承载能力,并且该复合结构能有效弥补金属骨无法降解的缺陷。     

基于RP的人工骨骼制造方法探索

针对目前基于快速成形的人工骨骼制作方法中存在的问题,提出基于快速在成形的人工骨烧结制造工艺方法,研制了气压式熔融沉积快速成形系统（AJS）,该方法达到材料、成形、生物活性的统一。其特点是人工骨肉部微孔的数量、大小,分布及形状可人工影响和控制。     

人工骨3D打印与铣削复合加工研究

针对人工骨高效精密制造的需求,展开PEEK材料人工骨高效3D打印与精密铣削复合加工研究。基于响应面方法,以PEEK材料人工骨制造的高储能模量、高效率、低耗材和高表面质量为目标,建立FDM型3D打印与铣削工艺参数的响应值回归数学模型,并据此进行工艺参数优化。得出3D打印最优参数组合为:层厚0.43 mm,内部填充密度55.05%,外周轮廓1.39圈。铣削最优参数组合为:背吃刀量0.2 mm,主轴转速3 500 r/min,进给量0.06 mm。进一步的复合加工试验验证了所构建的数学模型及优化的参数。该研究为PEEK材料人工骨的高效精密制造提供了一种复合加工方法,并奠定了复合加工的工艺参数基础。     

基于细胞沉积的人工骨微管设计及三维流场分析

针对人工骨微管中细胞均匀粘附和营养成分顺利运输所需流速条件,研究支管与主管道之间的夹角对支管中流速的影响以及沿主管道不同位置的支管中液体速度分布,并结合自然骨微观结构以及流体力学中的能量守恒和流量守恒原理,提出一种强化微循环结构并进行三维粘性流场数值分析,将分析结果与单纯仿形结构的流场分析结果比较,结果表明,该结构流速分布更均匀,支管内流速得到很大程度的提高,有利于细胞均匀粘附和进一步提高人工骨设计孔隙率。     

基于DSP的大电机线圈内部缺陷无损检测系统

在电机制造厂的大型电机线圈绝缘体发空的检测中,采用的是人工的"听声法",人为因素较多.文中根据大型电机无内部缺陷线圈与有内部缺陷线圈声学特性的差异,设计出一种基于TMS320F2812 DSP的大型电机线圈无损检测系统.该系统包括了敲击系统、信号检测系统和DSP系统.通过对所设计的硬件电路进行模拟仿真和局部硬件测试,完成了硬件平台的开发,并开发了相应的应用软件,使系统基本上能实现线圈的内部缺陷在线无损检测.     

机载式营养管沙障制作铺设装置设计与研究

针对我国沙漠化防治和工程化治沙的需要,研究设计出了一种将生物固沙与机械固沙结合起来进行沙漠化防治的管状沙障制作一铺设联合装置.该装置由行走及支撑系统、储料箱、进料器、成型器、沙障制作及铺设系统组成,在不同牵引机械的带动下可以实现两行或多行营养管沙障的同步制作与铺设.论文扼要分析该机器沙障制作与铺设原理,并讨论营养管沙障所用材料的选择、传动系统设计、营养管成型方式、纵封器设计及营养管封装与进料速度的确定.     

定制化骨替代物的空间定位

为了保证定制化人工骨替代物植入人体并与人骨连接后具有正确的相对位置,提出了利用人骨表面的自由曲面实现骨替代物的空间定位的原理和方法,并利用反求工程和快速原型完成个体定制的骨替代物及其定位器的设计与制造,成功地应用于临床。实践证明定制化骨替代物的植入手术能否成功,定位是一个关键技术环节。定位问题涉及到定制化骨替代物的设计、制作和手术的全过程,提出的定位原理和方法在实际应用中被证明是行之有效的,能够有效地保证手术的质量。     

基于离散单元法多孔陶瓷微球骨支架的微观结构分析

人工骨支架的孔隙率是评价体液在人工骨内部循环和细胞生长能力的重要参数,利用离散单元法分析模拟人工骨支架制备过程中HA微球的堆积过程,实现了对堆积内部微观情况的预测。本文以PFC3D软件为平台对HA石微球人工骨支架的微观结构进行了模拟仿真,从而通过改变HA微球和可速溶性小球的数量比及半径值,实现孔隙率可控,得出配位数为6时,HA微球人工骨支架的孔隙率为0．59,在满足力学性能的条件下,与人骨组织的孔隙率最为接近。     

含微通道网络的再生支架3D打印成形工艺和系统及试验研究

3D打印技术在构建个性化的人工组织和器官方面具有独特优势和发展潜力,然而目前在构建具有优良代谢性能的人工组织方面也还存在很多技术壁垒。在秉承3D打印技术优势基础上,综合考虑生物材料的反应成形特性,提出一种能够直接成形微尺度中空纤维,再三维叠层制造,从而直接获得内含微通道网络的再生支架的3D打印成形工艺;基于管材无模拉伸理论,定量分析微尺度中空纤维在被三维搭接过程中的拉伸变形,为工艺优化和参数调控奠定了理论基础;在给出相应成形系统的关键组成和技术要点基础上,进行了三维再生支架的制备试验及性能测试与分析。试验结果表明,提出的工艺及系统存在巨大的应用潜力,为有效解决人工再生组织血管化问题提供了一种全新的技术途径。     

Microscopy analysis of bone marrow-derived osteoprogenitor cells cultured on hydrogel 3-D scaffold

Bone marrow contains progenitor cells that are able to differentiate into several mesenchymal lineages, including bone. These cells may also provide a potential therapy for bone repair. The purpose of this study was to select the osteoprogenitor cell subpopulation from bone marrow-derived mesenchymal stem cells (MSCs) and to test the ability of a hydrogel scaffold to support growth and osteogenic differentiation. MSCs isolated from rat femur bone marrow were cultured in DMEM medium supplemented with antibiotics, FCS, and L-glutamine. Osteogenic supplements (dexamethasone, sodium beta-glycerophosphate, and ascorbic acid) were added for one, two or three weeks. A selective subpopulation of osteoprogenitor cells was identified by immunohistochemistry, general morphology, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Committed osteogenic cells were transferred to a 3-D hydrogel scaffold and cultured for an additional week. In standard culture, the osteoprogenitor cells formed cell clusters identified by Alizarin red S staining and by positive osteocalcin immunostaining. The number of osteoprogenitor cells, matrix synthesis, and mineralization increased gradually up to three weeks in culture. Mineral deposition in the matrix analyzed by EDS revealed the presence of calcium and phosphate ions at a Ca/P molar ratio of 1.73 in both the osteogenic cultures and the scaffold osteoprogenitor culture. Histological preparations revealed cell clusters within the hydrogel scaffold and SEM analysis revealed cell clusters attached to the scaffold surface. It is concluded that the hydrogel scaffold can support growth and differentiation of osteogenic cultures including mineralization and can potentially serve as a bone graft substitute containing committed osteoprogenitor cells.     

Regularized phase tomography enables study of mineralized and unmineralized tissue in porous bone scaffold

Regularized phase tomography was used to image non‐calcified fibrous matrix in in vitro cell‐cultivated porous bone scaffold samples. 3D micro‐architecture of bone and bone scaffold has previously been studied by micro‐computed tomography, synchrotron radiation (SR) micro‐computed tomography and microdiffraction. However, neither of these techniques can resolve the low‐calcified immature pre‐bone fibrous structures. Skelite porous scaffold discs were seeded with osteoblasts, a combination of osteoblast and pre‐osteoclasts and, as controls, with pre‐osteoclasts only, and then cultivated for 8 weeks. They were subsequently imaged using SR propagation‐based phase contrast imaging. Reconstructions using a regularized holographic phase tomography approach were compared to standard (absorption) SR micro‐computed tomography, which show that quantitative analysis, such as volume and thickness measurements, of both the calcified fraction and the immature bone matrix in the reconstructed volumes is enabled. Indications of the effect of this type of culture on Skelite, such as change in mineralization and deposit of mature bone on the walls of the scaffold, are found. The results are verified with a histological study.     

再生骨支架内部结构性能的综合评价

在分析影响再生骨支架内部微观结构性能因素的基础上,构建了支架内部结构性能的综合评价指标体系。根据各项评价指标对支架的生物活性、力学强度、降解速度等性能的影响程度,建立支架内部结构性能的层次分析模型;基于层次分析法(AHP)理论和计算方法,确定各项评价指标在内部结构性能综合评价中的权重值。基于灰色关联度分析的评价理论,构建支架内部结构性能的综合评价模型;计算各项评价指标的灰色关联度值,以此综合评判支架内部结构性能的优劣,保证再生骨支架具有良好的生物活性、较好的力学性能以及均衡的降解速度。     

3D visualization and quantification of rat cortical bone porosity using a desktop micro-CT system: a case study in the tibia

Although micro-computed tomography (micro-CT) has become the gold standard for assessing the 3D structure of trabecular bone, its extension to cortical bone microstructure has been relatively limited. Desktop micro-CT has been employed to assess cortical bone porosity of humans, whereas that of smaller animals, such as mice and rats, has thus far only been imaged using synchrotron-based micro-CT. The goal of this study was to determine if it is possible to visualize and quantify rat cortical porosity using desktop micro-CT. Tibiae (n = 10) from 30-week-old female Sprague-Dawley rats were imaged with micro-CT (3 μm nominal resolution) and sequential ground sections were then prepared. Bland-Altman plots were constructed to compare per cent porosity and mean canal diameter from micro-CT (3D) versus histology (2D). The mean difference or bias (histology-micro-CT; ±95% confidence interval) for per cent porosity was found to be -0.15% (±2.57%), which was not significantly different from zero (P= 0.720). Canal diameter had a bias (±95% confidence interval) of -5.73 μm (±4.02 μm) which was found to be significantly different from zero (P < 0.001). The results indicated that cortical porosity in rat bone can indeed be visualized by desktop micro-CT. Quantitative assessment of per cent porosity provided unbiased results, whereas direct analysis of mean canal diameter was overestimated by micro-CT. Thus, although higher resolution, such as that available from synchrotron micro-CT, may ultimately be required for precise geometric measurements, desktop micro-CT--which is far more accessible--is capable of yielding comparable measures of porosity and holds great promise for assessment of the 3D arrangement of cortical porosity in the rat.     

快速成形中PAN基碳纤维/HA力学性能模拟研究

在人工骨支架增材制造过程中,为了制造出具有不同力学性能的人造骨支架适合不同病患,提出利用分子动力学(Molecular dynamics,MD)模拟方法,研究所用基体复合材料(聚丙烯腈(Poly acrylonitrile,PAN)基碳纤维和羟基磷灰石(Hydroxyapatite, HA))表面之间的相互作用及力学性能。分别在原子模拟凝聚相优化分子势能力场(Condensed-phase optimized molecular potentials for atomistic simulation studies,COMPASS)和通用力场(Universal force field,UFF)下,对比计算HA和PAN基碳纤维/HA的力学性能,并比较其弹性模量和泊松比,证明羟基磷灰石是一种各向异性材料,并给出羟基磷灰石中添加PAN基碳纤维可以有效改善其力学性能。针对沿不同剪切方向上的PAN基碳纤维/羟基磷灰石进行动力学计算,表明在不同的力场下,羟基磷灰石均是在沿(110)剪切面上与聚丙烯腈纤维产生的结合能值较大。结合径向分布函数分析,揭示了PAN/HA复合材料主要是通过PAN中的N原子与HA表面发生强作用,从而提高PAN/HA基体力学性能。     

Wnt3a-induced ST2 decellularized matrix ornamented PCL scaffold for bone tissue engineering

The limited bioactivity of scaffold materials is an important factor that restricts the development of bone tissue engineering. Wnt3a activates the classic Wnt/β-catenin signaling pathway which effects bone growth and development by the accumulation of β-catenin in the nucleus. In this study, we fabricated 3D printed PCL scaffold with Wnt3a-induced murine bone marrow-derived stromal cell line ST2 decellularized matrix (Wnt3a-ST2-dCM-PCL) and ST2 decellularized matrix (ST2-dCM-PCL) by freeze-thaw cycle and DNase decellularization treatment which efficiently decellularized >90% DNA while preserved most protein. Compared to ST2-dCM-PCL, Wnt3a-ST2-dCM-PCL significantly enhanced newly-seeded ST2 proliferation, osteogenic differentiation and upregulated osteogenic marker genes alkaline phosphatase (Alp), Runx2, type I collagen (Col 1) and osteocalcin (Ocn) mRNA expression. After 14 days of osteogenic induction, Wnt3a-ST2-dCM-PCL promoted ST2 mineralization. These results demonstrated that Wnt3a-induced ST2 decellularized matrix improve scaffold materials’ osteoinductivity and osteoconductivity.     

同轴骨组织工程支架降解特性研究

为使抗骨结核药物在病灶区长期维持一定浓度,并促进术后缺损处的骨修复,应用羟基磷灰石、聚乙烯醇、丝素蛋白作为药物载体材料,结合自制机械式挤出装置制备同轴梯度骨组织工程支架.为使骨组织工程支架顺利植入体内,且保证支架负载的药物持续缓慢地释放,现对药物载体材料骨组织工程支架降解性能进行测试.研究发现降解10周后,无丝素蛋白的...