Room 3 Schedule
Collins 320
Wednesday, April 15th, 2026
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Methyl halides are volatile organic compounds that contribute to the destruction of the stratospheric ozone layer. Plants are major contributors to global methyl halide emissions. Methyl halides are produced in plants by SAM-dependent halide/thiol methyltransferase (HTMT) enzymes, encoded by HARMLESS TO OZONE LAYER (HOL) genes. The physiological role of HOL proteins in plants remains largely unknown, and HTMT activity has only been characterized in HOL homologs from flowering plants. In this study the putative HOL homolog from the moss Physcomitrella patens (PhyscoHOL) was recombinantly expressed, purified, and tested for HTMT activity using a high performance liquid chromatography (HPLC)-based enzyme assay.
Faculty Sponsor: Alison Fisher
Discipline: Chemistry -
Methyl halides catalyze the destruction of stratospheric ozone. In a variety of terrestrial plants, the production of methyl halides is catalyzed by S-adenosyl-L-methionine (SAM)-dependent halide/thiol methyltransferase (HTMT) enzymesthat are encoded by the HARMLESS TO THE OZONE LAYER (HOL) genes. Previous researchers have characterized Arabidopsis thaliana HOL (AtHOL1) proteins, and found that AtHOL1 prefers thiocyanate, a pseudohalide, as the substrate followed by bromide then chloride. In this research, cell-free extracts of Osmunda regalis and Dryopteris filix-mas ferns were prepared and analyzed for potential SAM-dependent HTMT activity.
Faculty Sponsor: Alison Fisher
Discipline: Chemistry -
Plants are responsible for producing methyl halides, volatile organic compounds that deplete the ozone layer. This phenomenon is facilitated by a family of enzymes known as halide/thiol methyltransferases (HTMTs). An HTMT in the model organism, Arabidopsis thaliana, was characterized and designated AtHOL, or “HARMLESS TO OZONE LAYER”. Several putative HOL enzymes have been identified, including one from the moss, Physcomitrella patens designated PhyscoHOL. In this research, I aimed to determine whether PhyscoHOL has HTMT activity. I recombinantly expressed PhyscoHOL and conducted assays on the protein. The enzyme activity of PhyscoHOL can give insights into why the protein evolved in plants.
Faculty Sponsor: Alison Fisher
Discipline: Chemistry, Arthur Payton Scholarship -
Methyl halides are a significant ozone-depleting substance, the production of which has been linked to halide-thiol methyltransferase (HTMT) activity in a variety of phytotrophic organisms. For plants in the order Brassicales, HTMT activity is linked to wound response and glucosinolate detoxification. Despite their ubiquity, the evolutionary purpose of HTMTs in plants lacking glucosinolate pathways remains unknown. Ancient vascular plants that produce methyl chloride may yield insight into the evolutionary purpose of HTMT enzymes. Analysis of cell-free extracts from ferns Cyathea cooperi and Osmunda japonica with HPLC indicate the presence of HTMT enzymes with activity towards chloride and iodide in ferns.
Faculty Sponsor: Alison Fisher
Discipline: Chemistry -
Rylene-imide dyes are useful chromophores that have the potential to be used as fluorescent sensors to test the effectiveness of molecular capsules for drug delivery purposes. These dyes are able to be used as the base fluorophore for a sensor to detect the formation of host-guest complexes in aqueous mediums. For this study, we are conjugating 1,8-naphthalimide to a series of cationic amines acting as electron acceptors for photoinduced electron transfer (PET). In this talk, we will discuss our successes and challenges in designing a divergent synthesis generating a 1,8-naphthalimide able to be differentially substituted with different amines.
Faculty Sponsor: Cooper Battle
Discipline: Chemistry, Arthur Payton Scholarship -
Fluorescent molecules are widely used to detect chemical interactions because their brightness changes depending on their environment. This project uses organic synthesis to design fluorescent donor–acceptor molecules with tunable electronic properties. By chemically modifying rylene dye derivatives with electron-donating or electron-withdrawing groups, we create molecules whose light emission depends on their electronic structure. Fluorescence spectroscopy is then used to study how these changes affect charge transfer and brightness. By correlating donor structure with photophysical behavior, this study establishes design principles for optimizing fluorescence “turn-on” sensing in supramolecular host–guest systems.
Faculty Sponsor: Cooper Battle
Discipline: Chemistry -
Chemists are interested in developing antioxidants as therapeutics for Alzheimer’s disease, heart disease, and cancer. The Duncan group is investigating caffeic acid - polysaccharide complexes as vehicles for quenching reactive oxygen species. Prior work established successful attachment of caffeic acid to PAAG as long as the catechol of caffeic acid is protected as a cyclic carbonate. The mechanism of this reaction, in particular the nucleophilic ring opening of the cyclic carbonate, is the focus of this investigation. Through quantifying these observations with H1NMR kinetics experiments, our findings indicate competing interactions regarding the cyclic carbonate of the modified caffeic acid.
Faculty Sponsor: Andrew Duncan
Discipline: Chemistry -
Cancer is often treated with transition-metal based chemotherapies, which have significant adverse side effects. Imidazolium-bis(imidazole)tetrachlororuthenate(III) (ICR) is a ruthenium-based chemotherapeutic in development that is both more targeted and less harmful than previous chemotherapeutics; however the mechanism of action is currently unknown. Raman spectroscopy of aqueous ICR yielded insight into the ICR aquation reaction, a vital component of the unknown mechanism of action. Kinetic parameters were determined from quantitative Raman spectroscopy measurements. Computational modelling of aqueous ICR using ORCA allowed for novel analysis of this Raman data and identification of a newly observed ICR aquation product vibrational mode (O-H rocking).
Faculty Sponsor: Chuck Williamson
Discipline: Chemistry -
Endocrine-disrupting compounds are hazardous when released into ecosystems. Of these compounds, estrogens are prevalent within natural wastewaters. During wastewater treatment, estrogens are halogenated and degrade when exposed to sunlight after their release into natural waters. In the interest of assessing the ecological effects of transformation products within natural water systems, we investigated the structures of these photoproducts using nuclear magnetic resonance (NMR) spectroscopy. We found that the structures deduced via NMR support previous transformation product structures determined by mass spectrometry.
Faculty Sponsor: David Griffith
Discipline: Chemistry -
Ethinylestradiol (EE2) is a synthetic estrogen used in birth control, which is known to have harmful effects on aquatic life at low concentrations. However, many reported concentrations of EE2 in the water supply far exceed reasonable estimates. Here, we test the hypothesis that surfactant compounds with similar masses to EE2 are responsible for overestimates of EE2 concentrations. Liquid chromatography and mass spectrometry analysis of common surfactant mixtures finds similar polarities and identical masses to interfering masses previously found in wastewater samples. This suggests that methods for detection of EE2 should be reevaluated.
Faculty Sponsor: David Griffith
Discipline: Chemistry -
This work expands on the ‘walking droplet’ project, studied for its behavior analogous to a quantum system, in which a bath of oil is vibrated vertically in order to prevent droplets from coalescing into the bath. We developed a novel method for the relocation of droplets, exploiting the fact that droplets will interact with waves on the surface of the oil bath. By using targeted CO2 laser pulses to generate waves on the bath's surface, we have enabled computer-controlled manipulation of droplet positions, allowing future researchers to assemble and study complex systems without painstakingly relocating droplets by hand.
Faculty Sponsor: Daniel Borrero
Discipline: Physics -
A Taylor-Couette system consists of two coaxial cylinders that can individually rotate, with liquid placed in between, and is used to study how liquids transition between smooth and turbulent flow. By just rotating the inner cylinder, the flow transitions to turbulence via supercritical transition where the flow goes through increasingly complex states before becoming turbulent. Within these different flow states, we perturbed the system to better understand the stability of these states and characterize supercritical transition. We found that perturbing the system via injection was effective in getting the state to change to a different stability.
Faculty Sponsor: Daniel Borrero
Discipline: Physics -
We studied spinners, small 3-armed plastic objects that, when placed on a vibrating liquid bath, produce capillary waves that cause them to rotate. A perfect pitchfork bifurcation (a stable state bifurcates into two stable states and one non-stable state) of non-chiral spinner rotation was achieved by increasing the driving amplitude of a shaker driven bath, until rotation (counter)clockwise became stable. Conversely, “kicking” chiral spinners from their natural to oppositely rotating state demonstrated an imperfect pitchfork bifurcation. These results show the spinner system serves as a controllable macroscopic system to explore complex non-linear dynamics with broken symmetry.
Faculty Sponsor: Daniel Borrero
Discipline: Physics -
Myosin VI is a molecular motor that transports cargo through cells using the energy of ATP hydrolysis. Myosin does not move uniformly. Its speed changes depending on the force it experiences. The experimental method we use is inspired by a recently pioneered technique called harmonic force spectroscopy. This technique applies force to the motor in a sinusoidal pattern, and allows for multidimensional data collection. We have increased confidence in detecting binding events and avoid false positives. These steps will allow future experiments to confirm pre-existing one dimensional datasets and explore the kinetics of myosin VI in 2D.
Faculty Sponsor: David Altman
Discipline: Physics