Dr. Steven Harrellson
Department of Physics
Hygroscopic biological matter in plants, fungi and bacteria make up a large fraction of Earth’s biomass. Although metabolically inert, these water-responsive materials exchange water with the environment and actuate movement and have inspired technological uses. Despite the variety in chemical composition, hygroscopic biological materials across multiple kingdoms of life exhibit similar mechanical behaviors including changes in size and stiffness with relative humidity. In this talk, I will discuss atomic force microscopy measurements on the hygroscopic spores of a common soil bacterium and the development of a theory that captures their mechanical behavior. This theory, based on the disruption of water structure, explains an extreme slowdown of water transport and successfully predicts a strong nonlinear elasticity. These results indicate that water not only endows biological matter with fluidity but can also provide rigid support. This unique behavior is why we call these materials "Hydration Solids".
Dr. Steven Harrellson is an alumni of PAMS.
This seminar is via Zoom: https://missouristate.zoom.us/j/96444437857