实验大鼠动脉粥样硬化模型升主动脉蠕变的实验研究

比较正常和动脉粥样硬化动物模型升主动脉的蠕变特性,确定动脉粥样硬化对升主动脉蠕变特性的影响.在日本岛津电子万能试验机上对正常和病态各10个试样进行蠕变实验.蠕变实验的应变增加速度为5%/s.设定实验时间为7 200 s,采集100个数,以一元线性回归分析的方法处理实验数据.结果表明:正常和病态组升主动脉蠕变最初600 s变化较快,之后应变缓慢上升,正常组7 200 s蠕变量为1.4%,病态组7 200 s蠕变量为0.97%.说明蠕变曲线是以指数关系变化的,动脉粥样硬化对升主动脉蠕变特性具有一定影响.     

几种药物治疗骨质疏松模型大鼠股骨蠕变特性的对比分析

比较正常对照组、骨质疏松动物模组、骨质疏松动物模型各治疗组大鼠股骨的蠕变力学特性,以蠕变特性指标确定各治疗组的治疗效果。以去卵巢方法复制骨质疏松动物模型,分别以中药、西药、VK、钙剂对模型动物进行治疗,15周后处死各组大鼠,取大鼠股骨进行蠕变实验,蠕变实验的应力增加速度为0.01MR/s,设定实验时间为7 200 s,采集100个数据,记录蠕变实验数据和曲线,以三参数模型处理实验数据。正常对照组中药组、西药组7 200 s应力松弛量差异不显著(P>0.05 s),模型组7 200 s蠕变量低于正常对照组、中药组、西药组,差异显著(P>0.05 s),VK组7 200 s蠕变量大于模型组与钙剂组,差异显著(P>0.05),模型组7 200 s蠕变量与钙剂组差异不显著(P>0.05)。各组蠕变曲线是以指数关系变化的。中药、西药治疗组大鼠通过治疗股骨蠕变力学特性恢复到原来的水平,VK治疗组大鼠股骨蠕变特性有一定恢复,钙剂对提高骨的蠕变力学特性无明显效果。模型组大鼠股骨蠕变特性发生了改变。模型组大鼠股骨蠕变特性改变最大。     

正常与病态眼角膜蠕变特性的对比分析

比较正常和病态眼角膜的蠕变力学特性为临床提供生物力学参数。采用人工捐献角膜,角膜移植后的10个眼角膜剩余部分、严重角膜溃疡术后严重并发症行角膜移植患者的病态眼角膜遗弃部分10个,在电子万能试验机上以0.1 MPa/s的应力增加速度进行蠕变实验。以归一化分析的方法处理蠕变实验数据。正常对照组眼角膜7 200 s蠕变量为0.16%,病态组眼角膜7 200 s蠕变量为0.12%,正常对照组7 200s蠕变量大于病态组,差异显著(P<0.05)。蠕变曲线是以指数关系变化的,病态组眼角膜蠕变特性发生改变。     

三参数模型计算股骨颈松质骨压缩蠕变方程

背景：无论是人工关节的研究还是股骨颈骨折内外固定都需要了解股骨颈松质骨的蠕变力学特性。 目的：通过实验定量得出股骨颈蠕变与时间的变化规律。 方法：在电子万能试验机上对股骨颈松质骨8个试样进行蠕变实验。模拟人体体温36.5 ℃的温度场下进行实验,蠕变实验的应力增加速度为0.11 MPa/s。设定实验时间为7 200 s,采集100个数据以三参数模型处理实验数据。 结果与结论：股骨颈松质骨蠕变,最初600 s变化较快,之后应变缓慢上升,7 200 s蠕变量为0.84%。结果显示蠕变曲线是以指数关系变化的,三参数模型能很好的拟合股骨颈松质骨的蠕变曲线和方程。     

股骨下端松质骨横向与纵向的蠕变特性

比较股骨下端松质骨横向和纵向取样的蠕变特性,为临床提供股骨下端松质骨的生物力学参数。取10个股骨下端标本,每个标本加工成长20 mm,宽20 mm,高20 mm的试样一个,共10个试样进行纵向蠕变实验。蠕变实验的应力增加速度为0.01 MPa/s,设定实验时间为7 200 s,采集100个实验数据。股骨下端松质骨纵向试样7 200 s蠕变量为0.26%,横向试样7 200 s蠕变量为0.33%。蠕变曲线是以指数关系变化的。股骨下端松质骨横向7 200 s蠕变量大于纵向。股骨下端松质骨横向和纵向具有不同的蠕变特性,其为各向异性粘弹性材料。     

胎儿脐带静脉的蠕变特性

为脐带静脉作为小口径移植材料的临床应用提供蠕变特性指标。对产妇年龄在22～28岁,胎龄37～40周自然分娩正常胎儿脐带静脉近胎盘段和远胎盘段各10个试样在日本岛津电子万能试验机上进行蠕变实验,模拟人体温在36.5±0.5℃的温度场下以0.01 Mpa/s的应力增加速度对试样施加应力,设定时间为7 200 s。采集100个数据,采用归一化分析的方法计算两组试样的归一化蠕变方程。两组试样蠕变曲线是以指数关系变化的,胎儿脐带静脉近胎盘段和远胎盘段7 200 s蠕变量差异显著(P<0.05)。胎儿脐带静脉近胎盘段和远胎盘段具有不同的蠕变特性。     

青年与老年人脊柱黄韧带黏弹性实验研究

目的比较青年与老年人脊柱黄韧带的应力松弛和蠕变黏弹性力学性质,为黄韧带退变的黏弹性力学机制提供依据。方法 20例老年腰椎退变病人黄韧带标本为老年退变组,20例青年腰椎外伤病人黄韧带为青年组,黄韧带标本均取自L4～L5间黄韧带。以1%/s的应变增加速度和0.5 MPa/s的应力增加速度分别对试样进行应力松弛和蠕变实验,实验温度设定为(36.5±0.5)℃。设定试验时间为7 200 s,采集90个应力松弛和蠕变数据。以统计分析和归一化的方法处理实验数据。结果青年组黄韧带7 200 s应力下降了1.42 MPa,老年组黄韧带7 200 s应力下降了1.91 MPa。青年组黄韧带7 200 s应变上升了3.39%,老年组黄韧带7 200 s应变上升了2.07%,两组7 200 s应力均下降,应变上升数据均有统计学意义(P<0.05)。应力松弛曲线是以对数关系变化的,蠕变曲线是以指数关系变化的。结论老年退变组黄韧带和青年组黄韧带相比,7 200 s应力松弛量和蠕变量降低,黏弹性力学性能发生改变。     

玻璃离子水门汀与光固化复合树脂的蠕变实验

通过蠕变实验得出了光固化型玻璃离子水门汀试样、银粉玻璃离子水门汀试样、光固化复合树脂试样的蠕变数据、蠕变曲线,建立了各组试样的蠕变函数方程,对比分析三种材料的蠕变特性,为临床提供蠕变力学参数。取光固化型玻璃离子水门汀试样、银粉玻璃离子水门汀试样、光固化复合树脂试样各10个,在电子万能试验机上进行蠕变实验,模拟人体温在36.5±1℃的温度下,以0.1 Mpa/s的应力增加速度对试样施加应力,每个试样采集100个实验数据,以归一化分析的方法处理蠕变数据,拟合蠕变曲线。光固化型玻璃离子水门汀试样7 200 s蠕变量为0.301%,银粉玻璃离子水门汀试样7 200 s蠕变量为0.262%,光固化复合树脂试样7 200 s蠕变量为0.230%,光固化型玻璃离子水门汀试样7 200 s蠕变量大于银粉玻璃离子水门汀试样7 200 s蠕变量,光固化复合树脂试样7 200 s蠕变量差异显著(P0.05)。各组试样蠕变曲线是以指数关系变化的。光固化型玻璃离子水门汀由于采用了光化处理,改善了其蠕变特性。     

气管软骨应力松弛的实验研究

以应力松弛的试验方法研究气管软骨的应力松弛特性,为临床提供气管软骨的应力松弛特性参数。在日本岛津电子万能试验机上对10个软骨进行应力松弛实验,应力松弛实验应变增加速度为50％／min,实验温度为（36．5&#177;0．65）℃,设定实验时间7200s,采集100个实验数据,以一元线性回归分析的方法处理实验数据。结果表明：气管软骨7200s应力松弛量为0．316MPa,7200s时应力松弛曲线基本达到平衡。气管软骨应力松弛曲线是以对数关系变化的．气管软骨为非线性粘弹性材料。     

正常与病态股骨头松质骨蠕变方程的比较研究

比较正常股骨头和股骨头坏死后股骨头的蠕变性质,为临床应用提供生物力学参数。在日本岛津电子万能试验机上,对正常与病态股骨头松质骨各8个试样进行蠕变实验。结果表明:股骨头松质骨在最初600 s变化较快,之后应力缓慢下降,正常组7 200 s蠕变量为0.19%,病态组7 200 s蠕变量为0.13%,病态组7 200 s蠕变量显著低于正常组(P<0.05)。说明股骨头坏死后打乱了松质骨骨小梁的正常排列,骨量丢失,从而对蠕变特性造成影响。     

人脊柱T_(6、7)段椎骨应力松弛蠕变实验研究

报道了用实验的方法对脊柱骨进行单向常应力－蠕变实验和单向常应变－应力松弛实验。得出应力、应变和时间相关的不同效应。     

Superporous hydrogels for cartilage repair: Evaluation of the morphological and mechanical properties

Despite extensive research in the design of biomaterials for articular cartilage repair, there remains a need for the development of materials with the mechanical compliance to function synergistically with healthy cartilage, but porous enough to allow for tissue integration. In this study, superporous hydrogels of poly(vinyl alcohol) and poly(vinyl pyrrolidone) were prepared using a novel technique consisting of a double emulsion process. The hydrogel emulsions were physically cross-linked by freeze-thaw cycling. The hydrogels had a high degree of porosity, determined using environmental scanning electron microscopy, a technique superior to any method that involves dehydrating the samples. Increasing the volume of organic solvent increased porosity, due to cross-linking of the hydrogel solution around the droplets in the emulsion, leaving pores where the organic solvent was present. Poly(lactic-co-glyclic acid) microparticles formed and were embedded in the matrix. The mechanical properties, measured in confined creep and in unconfined, uniaxial compression, were similar to native articular cartilage. The permeability of the samples was unaffected by changing solvent content, despite changes in porosity. These materials are good candidates for tissue engineering of cartilage because they can mimic mature cartilage mechanically while providing a porous matrix through which cells can migrate and proliferate.     

人股骨头关节软骨蠕变性能研究

为了解人股骨头关节软骨的力学性能，使用日本产ＡＧ－１０ＴＡ电子万能试验机，进行了软骨拉伸蠕变实验。基於蠕变曲线及归一化蠕变曲线基础，建立了蠕变函数及归一化蠕变函数，蠕变函数值与实验值最大相对误差为１１％，能较好的吻合。     

松质骨粘弹性性质的实验研究

本文对人胫骨近端的松质骨的粘弹性性质进行了实验研究和理论分析。蠕变和松弛实验获得了人胫骨松质骨材料具有的粘弹性性质 ,选用三参量模型得出了蠕变、松弛表达式。结论可供临床医学提供参考。     

生物软组织力学特性二维动态测试系统的研究

本文简述了生物软组织力学特性二维动态测试系统的设计。通过测量作用在软组织上的外力及软组织的形变，反映软组织力学特性。并以兔子腹部皮肤为对象，用本测试系统测量其滞后、松驰、蠕变特性，验证了本系统的可行性。     

Plastic properties of vertebrate smooth muscle (Taenia coli of the guinea pig)

Summary After extension and creep due to a constant load the taenia coli of the guinea pig shows plastic deformation. The deformation is partially abolished by complete unloading: to 51% in the relaxed and to 83% in the depolarized = contracted state. The quantitative relations between creep (N) and its time derivative (dN/dt) as well as those between stress relaxation (R) and dR/dt stated in our previous papers, remain valid if plastic deformations have occurred during these processes.     

多聚甲醛固定对大鼠椎骨黏弹性影响的实验研究

目的观察多聚甲醛固定对大鼠椎骨黏弹性力学性能的影响,从生物力学角度寻找松质骨样品的最佳保存方式。方法选择8周龄健康雌性SD大鼠20只,手术分离获得完整的腰椎L4和L5共40只,随机平均分为固定组和对照组,固定组置于4%多聚甲醛中固定72 h,对照组置于5 m L EP管内-20℃冷冻保存。两组随机各取10只分别行应力松弛和蠕变实验,7 200 s后收集样品并通过显微CT分析其微观结构变化。结果固定组松弛蠕变曲线相比对照组更加平滑,达到稳态的时间较短,且500 s和7 200 s的松弛蠕变总量明显降低(P0.01)。显微CT结果显示松弛蠕变实验会引起骨小梁断裂,且固定组比对照组骨小梁破坏更加严重。结论多聚甲醛固定法显著降低大鼠椎骨的黏弹性,在力学负荷下更易造成其微观结构破坏,不利于松质骨保存。     

Fatigue is More Damaging than Creep in Ligament Revealed by Modulus Reduction and Residual Strength

Following injury of a complementary joint restraint, ligaments can be subjected to higher than normal stresses. Normal ligaments are exposed to static (creep) and cyclic (fatigue) loading from which damage can accumulate at these higher than normal stresses. This study tracked damage accumulation during creep and fatigue loading of normal rabbit medial collateral ligaments (MCLs) over a range of stresses, using modulus reduction as a marker of damage. Creep tests were interrupted occasionally with unloading/reloading cycles to measure modulus. Test stresses were normalized to ultimate tensile strength (UTS): 60%, 30%, and 15% UTS. Not all creep and fatigues tests progressed until rupture but were stopped and followed by an assessment of the residual strength of that partially damaged ligament using a monotonic failure test. Fatigue loading caused earlier modulus reduction than creep. Modulus reduction occurred at lower increases in strain (strain relative to initial strain) for fatigue than creep. In other words, at the same time or increase in strain, fatigue is more damaging than creep because the modulus ratio reduction is greater. These findings suggest that creep and fatigue have different strain and damage mechanisms. Ligaments exposed to creep or fatigue loading which produced a modulus reduction had decreased residual strength and increased toe-region strain in a subsequent monotonic failure test. This finding confirmed that modulus reduction during creep and fatigue is a suitable marker of partial damage in ligament. Cyclic loading caused damage earlier than static loading, likely an important consideration when ligaments are loaded to higher than normal magnitudes following injury of a complementary joint restraint.     

Evolution of load transfer between hydroxyapatite and collagen during creep deformation of bone

While the matrix/reinforcement load-transfer occurring at the micro- and nanoscale in nonbiological composites subjected to creep deformation is well understood, this topic has been little studied in biological composites such as bone. Here, for the first time in bone, the mechanisms of time-dependent load transfer occurring at the nanoscale between the collagen phase and the hydroxyapatite (HAP) platelets are studied. Bovine cortical bone samples are subjected to synchrotron X-ray diffraction to measure in situ the evolution of elastic strains in the crystalline HAP phase and the evolution of viscoelastic strains accumulating in the mineralized collagen fibrils under creep conditions at body temperature. For a constant compressive stress, both types of strains increase linearly with time. This suggests that bone, as it deforms macroscopically, is behaving as a traditional composite, shedding load from the more compliant, viscoelastic collagen matrix to the reinforcing elastic HAP platelets. This behavior is modeled by finite-element simulation carried out at the fibrillar level.