Transport + Rheology + Simulations + MRI + NMR
Ceramics and Foams
These modern materials are invaluable to the alternative energy industry, food industry and medical industry. Our ability to increase the range of application of fuel-cells, or design next generation filtration systems for industry and medicine, depends on our ability to improve our understanding of transport in the complex structures of designed porous media such as new ceramics and foams.
Colloidal Suspensions
A colloidal suspension consists of solid particles (typically less than 10 µm) that are suspended by thermal Brownian motion and do not sediment in a suspending liquid. Fluids as diverse as paints and blood are classified as colloidal suspensions. They demonstrate fascinating shear-thinning, shear-thickening, particle migration and deposition effects – many of which are still not fully understood. Transport of colloidal suspensions under shear forces plays an elemental role in industry and biology. In natural systems, the dynamics of cellular bacteria in microbiology, red blood cells in physiology, and colloidal contaminants in earth formations impact the system function and transport. Understanding colloidal dynamics is also required for design of products such as drug delivery agents and microfluidic devices. Our lab can manufacture model colloidal suspensions of solid oil filled core shell particles suspended in water and stabilizing chemicals. The model particles allow magnetic resonance techniques to access transport features of the suspending liquid separate from the suspended particles.
Biofilms
Biofilms are microbial colonies that grow on surfaces. Their significance has encouraged a flood of recent research in areas as diverse as environmental bioremediation and biomedical applications. Biofilms are responsible for oral plaque and the persistent infections in catheters, medical implants and lungs. There is still not much known about the mechanics of and diffusion within the viscoelastic biopolymeric gel surrounding the bacteria and hence the effectiveness of agents to penetrate from the bulk fluid, but it is known that biofilms play a significant role in the resistance of bacteria to antibiotic treatment. The shear stresses experienced during growth may play a role in explaining antibiotic resistance and structural survival even during high and turbulent flow. While much is known about the growth state of free bacteria, much less is known about the structure-function relationships when cells are in the biofilm state. We have a strong collaboration with the Center for Biofilm Engineering and access to their expertise and equipment. We have used a wide range of magnetic resonance techniques to study the macroscale impacts of biofouling of fluid transport in medical, industrial and environmental materials and we study the fundamental rheological properties of the biofilm slime itself.
Porous Media
The underlying physics of transport in porous media is relevant to the aforementioned ceramics and foams as well as a plethora of other applications like industrial packed bed chemical reactors, transport in gels and tissues for drug delivery, storage of supercritical CO2 in natural formations and in sub-surface transport of environmental contaminants in the earth’s subsurface. Many porous media of interest have structures that generate complex dynamics which can be modeled by fractal and percolation theory concepts. MR methods provide unique data for scale dependent transport in porous media since most are opaque and not amenable to analysis by other methods. Modeling the impact on transport dynamics of biological and chemical reactions in porous media presents a significant challenge for design of environmental remediation strategies and new materials.
Gels
Polymeric gels are of major importance in technology and nature. The transport of particles and solvents in gels is a major feature of drug delivery strategies using nanoparticles, where gels are a model “tissue” and for drug delivery via gel swelling. Understanding the interplay between the underlying gel structure and transport processes will enhance these applications. Gels are also found in natural systems, such as the biofilms mentioned above, and their role in biological function an outstanding area of research interest.
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