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Stephanie McNamara

Publications and source records attributed to Stephanie McNamara.

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Rheological and Photoelastic Response of Hydrated Soft Granular Particles

Photoelasticity is a qualitative and quantitative optical technique to image internal stress distributions in transparent materials. In the past few decades, discrete photoelastic particles have been used as a proxy for dry granular materials in both static, quasistatic, and dynamic analogue experiments. The technique allows the visualization of force chains, determination of the location and magnitude of contact forces, and outputs a stress tensor for each particle with shear and normal stress components. To date, little to no work has investigated photoelastic suspensions, where photoelastic granular particles are immersed in a fluid medium, despite its relevance in industrial and natural applications. The introduction of a fluid phase yields additional considerations in the rheological and photoelastic behavior of our proxy particles. In this manuscript, we summarize the state-of-the-art in resolving forces in immersed photoelastic granular materials. We introduce characterization techniques to probe changes in rheological and optical properties of hydrated photoelastic particles, and we report considerations for use of photoelastic particles in immersion-based experiments. We intend for this work to provide the leading framework to study the hydrodynamic interactions in 2D systems of photoelastic particles immersed in a fluid medium.

cond-mat.soft

Novel Experimental Platform to realize One-dimensional Quantum Fluids

Templated porous materials, such as MCM-41, due to the uniformity of their onedimensional structure and scalability in synthesis, have emerged as an attractive medium for studying one-dimensional quantum fluids. However, the experimental challenge of synthesizing these materials with pore radii smaller than 15 Angstroms hinders the realization of a one-dimensional quantum liquid of helium within such systems, as the coherence length of helium is shorter than the pore radius. Recently, DelMaestro et. al. have preplated MCM-41 with Ar resulting in a reduction of the pore size and a softening of the adsorption potential allowing them to observe 1D Tomanga-Luttinger liquid like behavior. In this paper we present a novel method to obtain an even more ideal environment for studying the behavior of 1D 4He. We propose preplating MCM-41 pores with cesium (Cs) metal. The non-wetting nature of helium on a Cs-coated surface, coupled with the large atomic radius of cesium, creates an optimal environment for confining a quantum liquid of helium in one-dimensional geometry. We present preliminary measurements of adsorption isotherms and Small Angle X-ray Scattering studies that 1reveal a reduction in pore radius upon preplating MCM-41 with Cs, demonstrating promising prospects for facilitating the realization of one-dimensional quantum fluids in templated porous materials.

cond-mat.mtrl-sci