2019 Projects

Daniel Borrero-Echeverry, Assistant Professor of Physics

When a small droplet of oil is dropped into a container filled with oil, it splashes before coalescing with the fluid bath. However, in order to do so the droplet must clear the air layer separating it and fluid bath. It was recently discovered that if the fluid bath is vibrated vertically, the air layer can transfer sufficient momentum to the droplet, so that instead of coalescing it bounces upward and can remain suspended indefinitely. As it bounces, the droplet creates small ripples on the surface of the bath, which affects how the droplet will bounce. This interaction between droplets and their own wave fields leads to dynamics that have previously been thought to be restricted to quantum mechanics such as quantized bound states. This summer we will build an apparatus for studying bouncing drops and focus on two projects:

1.)  Implementing synthetic schlieren imaging for quantifying deformation of the fluid interface: In this technique a pattern of dots is placed at the bottom of the fluid bath. As the fluid surface is deformed by the bouncing drop, the dot pattern appears to shift as light is refracted across the curved surfaces in the wave field.  By analyzing the shifts in the dot pattern, the deformation of the fluid surface can be quantified.

2.)  Implementing optical actuation of bouncing drops: Any perturbation to the fluid interface will also affect the dynamics of the bouncing droplets. We will implement a laser system to generate controlled disturbances to fluid surface, which will enable us to tune the behavior of the bouncing drops in a controlled manner.

Luke Ettinger, Assistant Professor of Exercise and Health Science

The objective of this investigation is to determine if persons medically diagnosed as pre-
diabetic (Type 2 diabetes mellitus) will demonstrate proprioceptive discrepancies as
measured by a joint position sense (JPS) task in the lower extremity. Further, we aim to
investigate the extent of which these errors compare to previous data on patients with
higher amounts of diabetic exposure.

In this cross-sectional study, we aim to collect 46 participants who are pre-diabetic and
healthy age and gender matched controls. Diabetic neuropathy scores will be collected
prior to proprioceptive testing. For proprioceptive testing, participants will perform leg
extensions to randomized target positions of 15°, 30°, 45, 60° degrees of elevation in
the sagittal plane, each target will be repeated a total of four times. Subjects will be
guided to target positions in the absence of visual feedback via auditory cues from a
custom JPS application. When the participant enters the target position, they
memorized the location of their limb in space and subsequently attempted to re-locate
this position in space. Proprioceptive errors from measured JPS output from the target
positioned, target remembered, target repositioned protocol will be quantified and
examined using statistical analysis.

David Griffith, Assistant Professor of Chemistry

In the Griffith research group, we are focused on understanding the chemical processes that control the fate of estrogens in aquatic environments. Estrogens are potent hormones that are excreted by vertebrates (e.g., humans and fish) and can enter natural waters through the discharge of treated and raw sewage. Estrogens disrupt the growth and proper development of aquatic organisms at extremely low (sub-ng L–1) concentrations. Yet, we know very little about the distribution and fate of estrogens in rivers, lakes, and oceans. To address this gap, my research group conducts fieldwork, laboratory, and modeling experiments to better understand environmental removal processes, characterize the primary mechanisms driving estrogen distributions, and develop methods to accurately measure estrogen concentrations in complex environments. We utilize a variety of analytical techniques, including high performance liquid chromatography, UV-visible spectroscopy, degradation kinetics experiments, tandem mass spectrometry, and high-resolution mass spectrometry. The results of our work will be used to mitigate the associated risk to aquatic organisms and human health. Projects this summer will focus on determining photo- and bio-degradation rates at environmentally relevant concentrations (ng L–1) as well as identifying transformation products using high resolution and tandem mass spectrometry. 

Rosa León Zayas, Assistant Professor of Biology

In the Leon-Zayas research lab, we are excited to understand the community composition and metabolic potential of microbial communities in various environments such as the deep ocean, the subsurface, and coral reefs. In order to answer questions about which microorganisms are present in these environments and what roles those organisms are playing in their ecosystems, we utilize computational biology tools to analyze DNA of the whole microbial community. Among the ongoing research themes in the lab are the discovery of genes involved in the production of novel bioactive compounds, for example antibiotics or anticancer. Also, we are looking to better understand microbial communities that live below the sediment surface in the ocean and hot springs, particularly searching for organisms called Lokiarchaea, that have been suggested to be the missing link between prokaryotes and eukaryotes.

This summer our research will focus on two different projects. The first project will involve the analysis of data from a Fijian coral reef to look for genes that are associated with secondary metabolite production. The second project will involve the generation of sequence data from hot spring sediment samples and the potential culturing of organisms that are important parts of the microbial ecosystem in those environments. 

Melissa Marks, Assistant Professor of Biology

Chuck Williamson, Professor of Chemistry

In the Williamson research group, we use lasers and other techniques to probe the chemical and physical properties of molecules. One major area of interest for us is the behavior of partially-miscible binary liquid mixtures. These are mixtures of two liquids, such as methanol and carbon disulfide, that are completely miscible above a certain critical temperature, but separate into two layers for certain composition ranges below that temperature. The separated layers, or phases, are also mixtures of the two liquids, but with differing compositions. We use elastic laser light scattering, Raman spectroscopy (inelastic laser light scattering), and nuclear magnetic resonance spectroscopy to study the properties of liquid-liquid mixtures.

This summer our focus will be on elastic laser light scattering. We use elastic laser light scattering to make maps of the macroscopic behavior of binary liquid mixtures. These maps are called phase diagrams, and they show the temperature boundary between one-phase and two-phase behavior as a function of composition. In recent years we have identified a region of the phase diagram that does not behave as expected: a small number of droplets separate out of solution at temperatures slightly higher than the main phase transition. This newly-identified behavior is very puzzling, but it appears to be fundamental in nature because it occurs in the exact same way in at least eight different liquid-liquid systems. Our goal for the summer is to learn more about these droplets by clarifying the conditions under which they form, and by hopefully isolating them for chemical characterization. We will also look for their presence in systems involving ionic liquids.