Collaborative Research: Investigation of Chemotaxis in Porous Media -- Visualization Experiments and Modeling

合作研究：多孔介质中的趋化性研究？可视化实验和建模该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。了解细菌在地下运输是至关重要的，在防止微生物污染的饮用水供应和成功实施生物修复计划。许多地下微生物群落是能动的，由于它们的鞭毛可以积极游泳。许多能动的细菌对化学引诱物表现出趋化性，然而，趋化性常常被排除在细菌转运模型之外。 我们的假设解决了两种情况，其中趋化性在理论上被预测为相关的，但没有实验证明：（a）理论上预测的趋化细菌的移动带可以在实验中观察到，并对应于由细菌消耗底物产生的化学梯度。(b)趋化性细菌迁移到低渗透性区域，以响应自由流动介质中产生的化学梯度。 我们的具体目标是：1。优化一种新型的可视化系统，用于在表面标记有传感分子的二维微模型中同时观察细菌转运和水化学浓度.在以下情况下使用可视化系统对假设a和B进行实验研究：（a）均匀多孔介质，其中可消耗的化学引诱物浓度最初是均匀的，并且应该出现移动的细菌带;以及（B）双渗透性多孔介质，其中化学引诱物从低渗透性区域扩散。建立一个孔隙尺度的数值模型来描述所观察到的输运现象。具体而言，格子玻尔兹曼模型将被推广到考虑细胞附着和努森扩散。为了开发达西规模的趋化性分析解决方案，并评估达西规模的移动-不动区的概念。我们将使用本提案中采用的视觉吸引力的成像技术来改善本科教育和社区推广，包括为中学女生举办的科学博览会和为高中教师提供的研究经验。我们还将为数学专业的学生提供一个研究建模任务的机会。

Collaborative Research: Investigation of Chemotaxis in Porous Media ? Visualization Experiments and ModelingThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Understanding bacterial transport in the subsurface is critical both in preventing microbial contamination of drinking-water supplies and in successful implementation of bioremediation schemes. Much of the subsurface microbial community is motile and can actively swim due to their flagella. Many motile bacterial species exhibit chemotaxis to chemoattractants, however, chemotaxis is often excluded from bacterial transport models. Our hypotheses address two scenarios in which chemotaxis has been theoretically predicted to be relevant, but not proven experimentally: (a) Theoretically predicted traveling bands of chemotactic bacteria can be observed experimentally, and correspond to chemical gradients created by bacterial consumption of substrate. (b) Chemotactic bacteria migrate into regions of low permeability in response to chemical gradients created in the freely-flowing media. Our specific objectives are:1. To optimize a novel visualization system for simultaneously observing bacterial transport and aqueous chemical concentrations in 2D micromodels whose surfaces are labeled with sensor molecules.2. To experimentally investigate Hypotheses a and b with the visualization system in the following scenarios: (a) a homogeneous porous medium where the consumable chemoattractant concentration is initially uniform and where traveling bacterial bands should occur; and (b) a dual permeability porous medium in which chemoattractant diffuses from the low permeability region.3. To develop a pore-scale numerical model to describe the observed transport phenomena. Specifically, a Lattice-Boltzmann model will be generalized to account for cell attachment and Knudsen diffusion.4. To develop Darcy-scale analytical solutions for chemotaxis and to evaluate the Darcy-scale mobile-immobile zone concept.We will use the visually appealing imaging techniques employed in this proposal to improve undergraduate education and community outreach, including a science fair for middle school girls and research experience for high school teachers. We will also offer a research opportunity for a mathematics major to work on modeling tasks.