首页> 外文会议>Micro/Nanoscale Heat Transfer International Conference 2008 >HARDENING OF THE PORCINE THORACIC AORTA SUBJECTED TO FREEZING AND THAWING: EXPERIMENTAL EVALUATION AND MATHEMATICAL MODELING
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HARDENING OF THE PORCINE THORACIC AORTA SUBJECTED TO FREEZING AND THAWING: EXPERIMENTAL EVALUATION AND MATHEMATICAL MODELING

机译:冻结和融化对猪胸主动脉的硬化:实验评估和数学建模

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Identifying changes in the mechanical behavior of blood vessels subjected to freezing and thawing, such as occur with cryopreservation, are of key importance. Excising pairs of fresh ring specimens from identical porcine thoracic aortas (n = 8 for each cooling rate), we carried out uniaxial tensile loading and unloading tests over the physiological stress range (first and second tests) and performed a loading test until the breaking point within the range of a load cell (third test). After the first test, one specimen of the pair was frozen at -80℃ at a cooling rate of -1℃ or -50℃/min and thawed, while the other was held at 5℃ as a control. At both cooling rates, for the specimens subjected to freezing, the ratios of the tangential modulus in the stress-strain curve (between 130 and 150 kPa) in the second test to that in the first test differed significantly (p < 0.01) from the respective ratios of the control specimens. We formulated a mathematical model of the stress-strain relationship considering elastic and collagen fibers and an incompressible fluid phase. We evaluated the working hypothesis that collagen fibers reduce their extensibility either by hardening as a mechanical change or by shortening as a geometric change. We attributed this response to the formation of dehydration-induced cross-linking in collagen molecules at the microscopic level.
机译:识别经受冷冻和融化的血管的机械行为的变化(例如冷冻保存时发生的变化)至关重要。从相同的猪胸主动脉中切取成对的新鲜环标本(每个冷却速率n = 8),我们在生理应力范围内进行了单轴拉伸加载和卸载测试(第一次和第二次测试),并进行了加载测试直到断裂点在称重传感器的范围内(第三次测试)。第一次测试后,将一对样品中的一个样品在-1℃或-50℃/ min的冷却速率下于-80℃冷冻并融化,将另一个作为对照。在两种冷却速率下,对于冷冻样品,第二次试验的应力应变曲线(130至150 kPa)的切线模量与第一次试验的切线模量的比值显着不同(p <0.01)。对照样品各自的比例。我们建立了考虑弹性和胶原纤维以及不可压缩流体相的应力-应变关系的数学模型。我们评估了工作假设,即胶原纤维通过机械变化而硬化或通过几何变化而缩短而降低了其可扩展性。我们将此反应归因于在微观水平上胶原分子中脱水诱导的交联形成。

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