Understanding how the rheological behavior of biological fluids is related to health

PI：Schultz，WilliamProposal number：1604903这项建议是基于这样一个假设，即健康是通过生物液的变化来反映的，其中最重要和最容易获得的是唾液，这些变化会影响生物液的流变性。这一假设进一步规定，唾液的流变学特征及其性质的量化可以提供关于一个人健康的信息。唾液的流变学类似于水，这使得测量非牛顿性质变得困难。毛细管破裂流变仪(CBR)通常用于确定此类流体的拉伸参数。建议用差分一维模型重新检查CBR基础，以消除在测量细丝中点处的半径稀释率时所需的较大修正系数。与以前的方法不同，新的分析识别驱动流动的曲率梯度，因此需要自由表面轮廓演变来准确确定拉伸特性。这一分析与在牛顿和初步唾液演示中观察到的串珠形成过程中的丝状进化是一致的。接下来，利用牛顿分析中的空间变化的表面张力来研究表面活性剂在细丝动力学中的作用，以及可以解释为粘性的长链分子(如粘蛋白)或表面活性剂(如肥皂膜)更显著的伸展粘弹性性质。与唾液粘弹性不同，表面活性在唾液细丝形成中的作用及其对健康诊断的影响尚未被考虑。表征唾液的流变性可以指导开发更有效的唾液替代品、刺激剂和治疗口干或吞咽困难的补液剂。联合PIS将与美国加纳生物医学工程部合作，研究在当地人群中普遍存在的吞咽困难问题。通过该项目开发的技术可以帮助确定其他生物和工业流体的特性。还计划开展促进妇女从事工程工作的活动，包括通过密歇根大学妇女方案向200多名4至6年级的女孩进行教育推广，并让本科生妇女参与研究。

PI: Schultz, WilliamProposal Number: 1604903This proposal is based upon the hypothesis that health is reflected by changes in biological fluids, most important and accessible of which is saliva, and these changes affect the rheological properties of biofluids. This hypothesis further stipulates that rheological characterization of saliva, and quantification of its properties, can provide information about a person's health. Saliva rheology is similar to that of water, making measuring non-Newtonian properties difficult. Capillary Break-up Rheometry (CBR) is commonly used to determine extensional parameters of such fluids. It is proposed to re-examine CBR foundations with differential one-dimensional models to eliminate the large correction factors required when measuring the radius-thinning rate at the filament midpoint. Unlike previous methods, new analysis recognizes curvature gradients that drive the flow and therefore the free surface profile evolution is required to accurately determine extensional properties. This analysis is consistent with filament evolution all the way through beads-on-a-string formation that they have been observed in Newtonian and preliminary saliva demonstrations. Next the spatially-varying surface tension in Newtonian analysis is used to study the role of surfactants in filament dynamics as well as the more prominent extensional viscoelastic properties of long-chained molecules (such as mucins) or by surfactants (such as in soap films) that could be interpreted as stickiness. Unlike saliva viscoelasticity, the role of surface activity in saliva filament formation and its implications on health diagnosis have not yet been considered. Characterizing saliva rheological properties could guide the development of more effective saliva substitutes, stimulants, and hydrating liquids for xerostomia or dysphagia. The co-PIs will collaborate with U. Ghana Biomedical Engineering Department to study dysphagia problems prevalent in local populations. Techniques developed through this project can help to characterize other biological and industrial fluids. There are also plans to engage in activities to promote women in engineering including educational outreach to over 200 4th through 6th grade girls through the University of Michigan FEMMES program and involving undergraduate women in research.