Endocrine Disruption Screening: Can Vertebrate Endocrine Disruptors Impact Invertebrate Molting?

Type: Graduate
Author(s): Dalton Allen Biology Justin Hunt Biology Marlo Jeffries Biology Laurel Skrnich Biology
Advisor(s): Marlo Jeffries Biology
Location: Basement, Table 9, Position 1, 1:45-3:45

Mysid shrimp (Americamysis bahia) have been utilized in routine marine toxicity assessments for decades. While mysids are a well-established model, there a key gaps in understanding how chemical exposure impacts their endocrine systems. Crustacean growth occurs through molting (i.e., shedding old exoskeleton), a process regulated by hormones, primarily ecdysteroids. Ecdysteroids are a class of steroid hormones that share similar chemical structures to vertebrate hormones (i.e., 17β-estradiol and testosterone), which have been suggested to disrupt molting in some invertebrates. Through powerful tools, like transcriptomics, potential genetic biomarkers may be identified following chemical exposure. These biomarkers could provide the basis for future research aimed at screening endocrine disrupting compounds using invertebrate models. The objectives of this work were to 1) assess whether known vertebrate endocrine disruptors (e.g., 17β-estradiol and trenbolone) would induce alterations in molting and growth and, 2) compare gene expression profiles between vertebrate endocrine disruptors and a model ecdysteroid (i.e., ponasterone A) using transcriptomic analysis. Ponasterone A induced predictable alterations in mass, molting, and ecdysteroid-related gene expression, reinforcing both the use of this compound as a positive control and these endpoints for assessing invertebrate endocrine disruptors. Vertebrate endocrine disruptors induced varied responses in the endpoints assessed, but neither acted in a manner comparable to ponasterone A. Future work may investigate the potential for differentially expressed genes identified in the transcriptomic analysis for screening of invertebrate endocrine disruptors.

Investigating diet-induced metabolic syndrome in a typical American versus Mediterranean diet model in C57Bl/6J mice

Type: Graduate
Author(s): Morgan Bertrand Biology Gary Boehm Psychology Logun Gunderson Psychology
Advisor(s): Michael Chumley Biology
Location: SecondFloor, Table 6, Position 2, 11:30-1:30

Metabolic syndrome (MetS) is a cluster of concurrent cardiometabolic risk factors, including increased waist circumference, hypertension, elevated triglyceride level, reduced high-density lipoprotein (HDL) cholesterol level, and hyperglycemia. The key pathophysiology of MetS is insulin resistance, resulting in a disruption of glucose and lipid metabolism in the liver and adipose tissue, which increases the risk of type II diabetes, cardiovascular disease, and stroke. The development of insulin resistance and related conditions is multifaceted, but risk can be mitigated with lifestyle modifications, including improved nutrition. In the US, a typical American diet (TAD) is full of highly processed foods high in saturated fats and refined sugars and is associated with increased insulin resistance and obesity risk. In contrast, adherence to a plant-based Mediterranean diet (MD) rich in unsaturated fats, fiber, and non-refined carbohydrates has been found to reduce disease risk. Despite the contrasting nutritional compositions, the average macronutrient distributions of these two human diet styles are similar (approximately 50% kcal carbohydrates, 15% kcal protein, and 35% kcal fat). Due to the comparable macronutrient ratios but contrasting nutritional composition, direct comparative analysis could uncover metabolic and cellular differences relating to their associated health outcomes.

There are few rodent studies in the literature that directly compare a TAD and MD. Further, studies often utilize a high-fat diet, consisting of 40-60% kcal fat, or individual nutrient supplements, such as olive oil, rather than comprehensive diet models. To address these limitations, our lab developed comprehensive, macronutrient-matched TAD and MD models that more closely mimic human diets in the U.S. and Mediterranean, respectively. A previous study in our lab found that six months of TAD consumption resulted in elevated body weight, increased inflammation, and excess hepatic lipid deposition, in comparison to the MD. Our current study looked to further characterize MetS under this diet model, specifically investigating obesity, insulin resistance, and dyslipidemia markers. Male and female C57BL/6J mice consumed either the TAD or MD from the age of 4 to 7 months. We found that after three months on diet, there were elevations in hepatic steatosis and serum cholesterol levels in both males and females on the TAD. However, other findings suggested early signs of insulin resistance in TAD males, but not females. Future studies will investigate MetS after 6 months on diet to better elucidate insulin resistance development and potential sex differences.

The enzymatic role of nucleosome ubiquitylation by BRCA1 in C. elegans

Type: Graduate
Author(s): Meagan McMann Biology Nathalie Carlon Biology Lucy McCollum Biology
Advisor(s): Mikaela Stewart Biology
Location: Third Floor, Table 1, Position 3, 1:45-3:45

BRCA1 protects genomic stability by signaling for the homologous recombination pathway, DNA repair, and transcriptional regulation. A pathogenic mutation in the BRCA1 region causes a higher predisposition to the development of breast and ovarian cancer. Our lab is exploring the different enzymatic functions of BRCA1 by looking at its role in histone ubiquitylation, leading to transcriptional regulation of certain parts of the genome. Join us to see our plan for connecting molecular mechanisms of a large, multi-functional gene to the phenotype of an organism. A homolog of BRCA1 is conserved in C. elegans as BRC-1. We propose that mononucleosome ubiquitylation is a key mechanism contributing to the cellular functions of BRC-1. Understanding the significance of mononucleosome ubiquitylation in BRC-1 with C. elegans gives insight into the mechanisms of genetic variations in BRCA1 and further expands C. elegans’ function as a model organism. We have generated a C. elegans mutant with two point mutations that alter the ability of BRC-1 protein to interact with the nucleosome and ubiquitinate histone H2A while retaining all other functions. We hypothesize this mutation increases DNA damage accumulation and disrupts transcriptional regulation to establish nucleosome ubiquitylation as a necessary precursor for these, but likely not all, BRC-1 functions. We compare three strains of C. elegans (wildtype, brc-1 knockout, and our mononucleosome ubiquitylation-deficient mutant) in different conditions designed to induce cellular stress or DNA damage accumulation. We find that BRC-1 nucleosome ubiquitylation contributes to embryonic survival under standard conditions as well as DNA damage-inducing conditions. We also share preliminary results regarding the role of nucleosome ubiquitylation in transcription regulation and reactive oxygen species generation. Our findings further the understanding of the many enzymatic functions of the large BRCA1 gene.

Investigating Mercury Transfer from Aquatic to Terrestrial Food Webs: The Influence of Distance from Pond Shorelines on Methylmercury Concentrations in Arctic Wolf Spiders

Type: Graduate
Author(s): Camryn Middlebrooks Biology Aleah Appel Biology Sommerlyn Babineau Biology Kurt Burnham Biology Ethan Cary Biology Titus Crawford Biology Sage Dale Biology Charlie Duethman Biology Aidan Duffield Biology Piper Dumont Biology Skyler Dunn Biology Madeline Hannappel Biology Sydney Hill Biology Ramsey Jennings Biology Ben Katzenmeyer Biology Chidi Mbagwu Biology David Peebles Biology Benjamin Strang Biology Emma Sullivan Biology Lance Viscioni-Wilson Biology Kimberlee Whitmore Biology Tyler Williams Biology David Wright Biology
Advisor(s): Matt Chumchal Biology
Location: Basement, Table 6, Position 2, 1:45-3:45

Mercury is emitted from various anthropogenic processes in temperate and tropical regions and is transported to northern latitudes via air and ocean currents. Although there are few point sources of mercury in the Arctic, elevated mercury levels have been observed in Arctic predators such as marine mammals, seabirds, fish, and spiders. This is concerning due to mercury’s known neurotoxic and teratogenic effects. Mercury deposited in the Arctic can be converted into its bioavailable form, methylmercury (MeHg), by aquatic bacteria. It can then be transferred into nearby terrestrial habitats by aquatic emergent insects. A previous study indicated that Arctic wolf spiders (Pardosa glacialis) collected from the shoreline of ponds had elevated concentrations of MeHg. In temperate zones, adult aquatic insects typically disperse within 30 meters of freshwater sources, suggesting that upland predators may consume fewer emergent aquatic insects, thereby reducing their contamination from these sources. While Arctic wolf spiders are ubiquitous predators across the tundra, it is unclear whether spiders collected in upland habitats are similarly contaminated with MeHg. The purpose of this study was to investigate the movement of mercury from aquatic to terrestrial food webs on the Pituffik Peninsula of northwest Greenland. Specifically, we examined the effects of shoreline proximity on mercury concentrations in Arctic wolf spiders. We collected Arctic wolf spiders and their insect prey at varying distances (0m, 10m, and 35m) from six freshwater ponds. We found a positive relationship between mercury concentrations and body size in P. glacialis. Spiders captured 35 meters away from the shoreline had significantly lower mercury concentrations than those captured at 0m or 10m from the shoreline. These results suggest that the dispersal of Arctic emergent aquatic insects declines with increasing distance from the shoreline and that emergent insects are an important source of mercury for Arctic wolf spiders.

Investigating the role of fused msrA/B and clpX in the resistance to cell-wall targeting antibiotics in Bacillus anthracis Sterne

Type: Graduate
Author(s): Aeron Pennington Biology Josey Austin Biology Salina Hona Biology Kelsey Waite Biology
Advisor(s): Shauna McGillivray Biology
Location: Basement, Table 5, Position 2, 1:45-3:45

The ClpXP protease plays a critical role in bacterial responses to external stressors, protein recycling, and virulence. The protease is highly conserved and composed of two subunits: ClpX, a regulatory ATPase, which recognizes and unfolds proteins, and ClpP, the proteolytic subunit. Our lab has identified that ClpX plays a role in resistance to cell-envelope targeting antibiotics and is critical for virulence in B. anthracis Sterne. However, it is unlikely that ClpX is directly mediating these effects. Rather, these effects are likely due to the dysregulation of the protein network maintained by ClpXP, which includes proteins involved in gene expression, such as transcription factors. Previously, we conducted a microarray and identified 119 differentially expressed genes between wild-type B. anthracis Sterne and a ΔclpX strain. One of the genes identified from the microarray is msrA/B, a fusion of the msrA and msrB methionine sulfoxide reductases (msr). Msr enzymes restore functionality to oxidized methionine residues; MsrA reduces S-form Met(O), and MsrB reduces R-form Met(O). Research with these enzymes has primarily focused on their role in resistance to reactive oxygen species (ROS). However, in S. aureus, msrA1 and msrB expression was induced upon exposure to oxacillin and other cell-wall active antimicrobial agents and not by ROS, indicating a potential connection between msrA/B and cell wall-targeting antibiotics. In B. anthracis Sterne, loss of msrA/B increases susceptibility to penicillin and vancomycin. However, this phenotype is not seen with cell-membrane targeting agents such as daptomycin, suggesting that the role of msrA/B in antimicrobial resistance may be limited to cell-wall active antibiotics. We are currently investigating the role in resistance to ROS but have seen no susceptibility to either H2O2 or paraquat. Future studies will look at changes in msrA/B expression in response to a variety of antibiotics and ROS stressors to better understand the role of this enzyme in regulating the response to these stressors in B. anthracis.

Investigating Breast Cancer-Associated Variants: From Bedside to Bench

Type: Graduate
Author(s): Jamison Speed Biology
Advisor(s): Mikaela Stewart Biology
Location: Basement, Table 3, Position 2, 1:45-3:45

Partner and Localizer of BRCA2 (PALB2) is a necessary linker protein between BRCA1 and BRCA2. In order to create this connection it interacts directly with BRCA1 via a coiled-coil domain in both proteins. Facilitating this linkage directs cells to fix double stranded DNA breaks (DSBs) through homologous recombination. The mutation L35P has been shown to disrupt this linkage forcing the cell to complete repair through alternate pathways that are not as accurate. This inaccuracy can lead to the accumulation of mutations and increase the risk of breast and ovarian cancers. The L35P variant within the coiled-coil domain of PALB2 has been linked with hereditary breast and ovarian cancer. However, it is unknown if loss of leucine in the interface is causing the decrease in binding or if it is the introduction of a proline into the coiled-coil region that is destroying the secondary structure thereby inhibiting binding. We are studying five variants of unknown significance (VUS) from PALB2 that are within the coiled-coil and are also proline substitutions. One of these mutations is within the binding interface and the other four are on the backside of the coil. We are investigating the structure and BRCA1-interaction of these VUS to directly connect structural changes in the coil to functional deficiencies. Currently we have found that these proline variants are inhibiting binding with BRCA1 through measuring heat exchange with isothermal titration calorimetry. We also plan on evaluating these variants through circular dichroism as well to assess if the secondary structure of PALB2 is affected as well.

Phylogeny and biogeography of the Asian tropical blueberries of tribe Vaccinieae (Ericaceae)

Type: Graduate
Author(s): Maverick Tamayo Biology Peter Fritsch Biology Mathew Hale Biology
Advisor(s): Matthew Hale Biology
Location: Third Floor, Table 3, Position 2, 11:30-1:30

Malesia is a vast phytogeographic region in Southeast Asia, spanning roughly one-fifth of the world’s circumference and considered one of the most biodiverse regions of the world. It is divided into three subregions: Sahul, Sunda, and Wallacea, primarily distinguished by their geological history and differences in floristic composition. Research based on fossil-calibrated phylogenetic trees has begun to provide insights into the historical phytogeography of Malesia, specifically regarding the reciprocal migration of plant lineages across the Sunda and Sahul regions known as the “Sunda-Sahul floristic exchange (SSFE).” This study aims to test the SSFE hypothesis with the use of the Asian tropical blueberry clade of tribe Vaccinieae (Ericaceae). Silica-dried specimens from previous fieldwork, garden-grown plants of wild origin, and herbarium specimens were used to extract genomic DNA. The samples were sequenced with the Angiosperms353 bait set, and a dated phylogenomic tree was constructed, incorporating all available genomic data from online repositories. Divergence time analysis and ancestral area reconstruction was performed to test the hypotheses of the SSFE. This research will serve as a steppingstone towards resolving the phylogeny and evolutionary history of tribe Vaccinieae. It will also form a foundation for assessing the conservation status of micro-endemic and threatened Asian tropical blueberry species, especially in Malesia. Lastly, this study will highlight the crucial role of botanical gardens and herbaria as vital repositories of natural history collections.

Using dry plants and DNA to unravel the story ferns have to tell

Type: Graduate
Author(s): Lucia Vargas Biology
Advisor(s): Matt Hale Biology Alejandra Vasco Biology
Location: Basement, Table 1, Position 3, 11:30-1:30

Understanding and documenting the diversity and distribution of species on Earth is crucial, especially in the face of habitat loss and species extinction. Without this knowledge, we risk losing valuable understanding of the natural world, including species with ecological, medicinal, or economic significance. Ferns, one of the oldest lineages of land plants, still hold many scientific mysteries, particularly in tropical regions where diversity is high and under-explored.
Herbarium specimens—dried plants collected and preserved over centuries—serve as critical windows into the past, allowing botanists to study plant diversity across time and space. When combined with modern tools such as imaging and DNA analyses, these collections become powerful data sources for unraveling evolutionary relationships, discovering new species, and improving our understanding of biodiversity. Our research focuses on Elaphoglossum, one of the most diverse and taxonomically challenging fern genera. Using herbarium specimens, powerful microscopes, and molecular phylogenetic studies, we are conducting a systematic review of the Elaphoglossum dendricola clade, a group of Andean ferns. Our aims are to clarify species boundaries, uncover undescribed species, reconstruct evolutionary relationships, and evaluate the conservation status of these ferns.
This poster presents preliminary results and outlines future directions of our research in tropical ferns, highlighting the importance of integrating collections-based taxonomy and molecular phylogenetics to explore and preserve tropical fern diversity.

Fishy fear: the development of a predator avoidance assay for fathead minnows

Type: Graduate
Author(s): Catherine Wise Biology Kate Davis Environmental Sciences Lilli Gonzales Biology Justin Hunt Biology Zoie Munoz Biology Marisa Ross Psychology
Advisor(s): Marlo Jeffries Biology
Location: FirstFloor, Table 2, Position 2, 11:30-1:30

The fathead minnows (Pimephales promelas; FHMs) have been the most utilized small fish model in North American ecotoxicity assessments for decades. However, the behavior of FHMs across their lifespan remains poorly characterized relative to other small fish models. Given the growing recognition of the importance of evaluating ecologically-relevant behavioral endpoints in environmental monitoring, aquaculture, and ecotoxicology, there is a need to develop assays to assess such behaviors in fish across multiple life stages. One class of ecologically-relevant behaviors is predator avoidance behaviors, which hold importance for the survival and propagation of fish populations. While the predator avoidance behaviors of adult FHMs (e.g., shelter seeking/hiding, freezing) have been well documented, there has yet to be a comprehensive study characterizing the responses of larval FHMs to chemical predator stimuli. Thus, the present study aimed to develop a behavioral assay that assesses predator avoidance behaviors of FHMs across multiple life stages. The specific predator stimulus was alarm cue, a chemical released from damaged or injured epidermal club cells of FHMs to signal conspecifics of a predator attack. In turn, the objectives were to 1) verify that the use of alarm cue collected from pond-reared donors induced predator avoidance behaviors, as measured via ToxTrac, an open-source tracking software, in adult fathead minnows, and 2) develop a predator avoidance assay for use in 14 days post-hatch (dph) larval FHMs using the alarm cue from pond-reared donors verified in adult FHMs. Exposure of adult FHMs to alarm cue collected from pond-reared donors induced significant changes in the predator avoidance behaviors detected by ToxTrac, verifying its use as a predator stimulus for lab-reared FHMs. Moreover, this study represents the first characterization of the behavioral response of 14 dph FHMs to alarm cue from pond-reared donors, providing insight into the maturation of predator avoidance behaviors of FHMs. Future work may investigate the sensitivity of the larval predator avoidance assay to chemicals with known neurological effects to validate its use as an ecologically-relevant behavioral assay in an aquaculture, ecotoxicity, or environmental management context.

Quantifying the Impact: White Nose Syndrome and Bat Population Dynamics

Type: Graduate
Author(s): Hongzhen Wu Biology
Advisor(s): Jiao Jing Biology
Location: SecondFloor, Table 6, Position 3, 11:30-1:30

White-nose syndrome (WNS), caused by a fungus called Pseudogymnoascus destructans, has caused dramatic declines in North American bat populations, with mortality rates exceeding 90% in some species. WNS has spread widely, now to southern regions such as Texas, and presents new challenges for disease modeling due to differences in climate and bat hibernation behavior. This study developed a open patch epidemiological model integrating bat populations from the Northeastern United States to examine how migration and disease exposure affect population dynamics. By modifying a standard SIR model, we analyzed interactions between wild and robust bat genotypes at varying levels of migration and frequency of disease pulses. Preliminary findings suggest that increased migration favors robust genotypes, while frequent disease pulses initially favor robustness but may eventually penalize it if disease prevalence remains low. These insights enhance our understanding of regional disease dynamics and provide a framework for conservation strategies aimed at mitigating WNS-driven biodiversity loss.

DIRECT ARYLATION OF UNACTIVATED ARENE USING EARTH ABUNDANT IRON/TETRA-AZA MACROCYCLIC COMPLEX

Type: Graduate
Author(s): Tahmina Afroz Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: SecondFloor, Table 7, Position 3, 1:45-3:45

DIRECT ARYLATION OF UNACTIVATED ARENE USING EARTH ABUNDANT IRON/TETRA-AZA MACROCYCLIC COMPLEX
The development of sustainable catalytic systems for carbon–carbon bond formation is of critical importance in modern synthetic chemistry. This study presents an iron-based catalytic system employing tetra-aza macrocyclic ligands as a cost-effective and environmentally benign alternative to palladium in direct arylation reactions. Using [Fe²⁺L6(Cl)₂] as the catalyst and molecular oxygen as the terminal oxidant, the direct C(sp²)–C(sp²) coupling of pyrrole with substituted phenylboronic acids was achieved under mild conditions, yielding 2-phenylpyrrole and its derivatives with moderate efficiency (up to 62%). The catalyst displayed broad substrate scope and functional group tolerance, effectively accommodating halogen, nitro, alkyl, and methoxy substituents. Mechanistic studies excluded a radical-mediated pathway and instead supported a non-radical oxidative mechanism involving an iron(III)-hydroperoxo intermediate. These findings underscore the potential of earth-abundant iron complexes in sustainable cross-coupling chemistry and set the stage for further exploration in heterocycle functionalization and pharmaceutical scaffold development.

Towards a Comprehensive Benchmark of Quantum Mechanical pKa Prediction: Conformational Sampling, Model Solvent, Basis Set, Density Functional, and Empirical Corrections for the SAMPL7 Dataset

Type: Graduate
Author(s): Donatus Agbaglo Chemistry & Biochemistry Minh Ho Biology
Advisor(s): Benjamin Janesko Chemistry & Biochemistry

Reimagined Route to Drug Discovery: Macrocyclization leads to 20 predicted and persistent products for chemical library development

Type: Graduate
Author(s): Liam Claton Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: SecondFloor, Table 8, Position 3, 11:30-1:30

In the pursuit of new ways to develop libraries of compounds for pharmaceutical drug discovery, the utilization of a robust and tunable macrocycle synthetic scaffold has led to the discovery of persistent and structurally well-defined conformational isomers. Targeting these macrocycles that exist as an ensemble of preorganized conformations represents a compromise between the pursuit of flexible molecules of undefined structure and rigid molecules biased towards a single conformation. This system is based on the quantitative dimerization of a monomer to afford macrocycle. When a single monomer is used, six unique structures are obtained. When two monomers are used, twenty unique structures are obtained. These different structures (conformational isomers) are accessed via hindered bond rotation with a barrier of ~18 kcal/mol and are observable by ¬1H NMR. Current drug discovery methods heavily rely on screening large chemical libraries of small, ridged molecules against protein targets and typically sacrifice entropy in favor of stronger ligand-target binding. Using our system, synthesis of 50 monomers allows for the generation of a library of over 10,000 structurally unique macrocycles. The goal of this work is to provide new chemical libraries for drug discovery.

Testing the Fundamental Kinetic Properties of Anti-Aging, Antioxidant Active Ingredients for Skincare

Type: Graduate
Author(s): Nora Del Bosque Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Basement, Table 5, Position 1, 1:45-3:45

EUK-134 is a manganese-salen complex widely used in anti-aging skincare formulations due to its potent antioxidant activity resulting from catalytic decomposition of reactive oxygen species. Despite its popularity, the fundamental kinetic properties that govern its efficacy and recyclability are not well understood, limiting its optimization in skincare products. As a result, the study presented here investigates the efficiency, sustained activity, and selectivity of EUK-134 in comparison to the Green lab ligand library by evaluating its turnover number (TON), turnover frequency (TOF), and reaction rate. Results indicate that while EUK-134 demonstrates high catalase-type activity and selectivity, the activity decreases with continuous exposure to H₂O₂, suggesting a need for re-application in real-world scenarios to achieve long-term protection. Additionally, selectivity studies show that peroxidase activity was observed, which may impact the stability of sensitive ingredients in formulations. These findings provide essential kinetic benchmarks to compare future small molecules and optimize EUK-134’s use in antioxidant skincare products. Without a clear understanding of these fundamental properties, we lack benchmarks to compare future small molecules that compete with EUK-134.

Influence of the Quinoline Moiety on the Pharmacological Properties of Tetra-aza Pyridinophanes and Their Anticancer Activity

Type: Graduate
Author(s): Sarah Dunn Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: SecondFloor, Table 5, Position 1, 1:45-3:45

The development of novel anticancer agents with enhanced selectivity and reduced toxicity remains a critical challenge in medicinal chemistry. In this study, we investigate the influence of the quinoline moiety on the pharmacological properties of tetra-aza pyridinophanes, with a focus on their anticancer activity. A series of structurally diverse derivatives were synthesized, incorporating variations in the quinoline moiety position and R-group functionalization. The compounds were characterized using multiple spectroscopic and analytical techniques, and their biological activity was evaluated in cancer cell lines. Results indicate that the presence of the quinoline moiety significantly improves anticancer efficacy compared to its absence, suggesting enhanced interactions with cellular targets. Furthermore, permeability studies reveal that the methoxy (-OMe) substitution on the pyridine ring enhances cellular uptake relative to the hydroxyl (-OH) counterpart. These findings highlight the potential of quinoline-functionalized tetra-aza pyridinophanes as promising candidates for targeted cancer therapy. By improving the selectivity between normal and cancerous cells, this work advances the design of next-generation chemotherapeutics with reduced systemic toxicity.

The Goldilocks Combination to Unprecedented Perovskites

Type: Graduate
Author(s): Maegyn Grubbs Chemistry & Biochemistry Sergei Dzyuba Chemistry & Biochemistry Zygmunt Gryczynski Physics & Astronomy Bong Lee Physics & Astronomy
Advisor(s): Jeff Coffer Chemistry & Biochemistry
Location: Basement, Table 4, Position 2, 11:30-1:30

Metal-halide perovskites are crystalline semiconductive materials with a tunable direct bandgap, defect tolerance, and high charge carrier mobility. These useful properties have led to application perovskites such as LEDs, solar cells, and more recently lasers.
In this project, cetyl ionic liquid (IL) enhanced Methylammonium Lead Tribromide perovskites thin films were studied on substrates with varying refractive indices to determine how refractive index impacts photophysical properties. Methylammonium Lead Tribromide perovskites have a refractive index of 2.19. In comparison glass, a common substrate, has a refractive index of 1.51 while yttrium-stabilized zirconium oxide (YSZ) is 2.15.
Thin films of Methylammonium Lead Tribromide grown on yttrium-stabilized zirconium oxide (YSZ) in the presence of an ionic liquid are found to be strongly emissive in the green at a wavelength of 535 nm (with quantum efficiency values above 60%). The associated photoluminescence excitation (PLE) spectra show an unprecedented series of distinct peaks, one set with an average energy separation of ~200 milli-electron volts, the other set with a ~100 milli-electron volt separation indicating possible Giant Rashba Splitting. The preparation and structure of these films, along with origins of this splitting, are presented.

P-Stereogenic Phosphorus Compounds as Organocatalysts for Asymmetric Synthesis

Type: Graduate
Author(s): Ellis Guernsey Chemistry & Biochemistry
Advisor(s):
Location: Basement, Table 6, Position 3, 11:30-1:30

Asymmetric chemical transformations are essential, given that most pharmaceuticals are chiral. However, the industrial implementation of an asymmetric catalyst relies on basic economic principles. For an economically viable synthesis, catalysts should be readily available, cost-effective, and environmentally sustainable. We are synthesizing and evaluating a series of chiral phosphorus acids (CPAs) as catalysts for asymmetric transformations. Building on our previous work, we are developing P-chiral phosphorus acids as Brønsted acid catalysts for the acid-catalyzed asymmetric transformations.

Cancelling Cancer through Copper capture

Type: Graduate
Author(s): David Mingle Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry

Copper plays particularly important roles in tumor growth and metastasis, making it a new target for anti-cancer therapies. The goal of this project is to exploit the pathways that cancer uses for proliferation as a target to inhibit cancer cell growth. To achieve this, tetra-aza macrocyclic small molecules will be used to sequester copper from the copper metabolizing pathways, recently we have discovered these molecules have high affinity for copper, water solubility, low toxicity, available in gram-quantities, and well-characterized. Our lead compound will be evaluated for anticancer activity on normal and breast cancer cells. This project also seeks to examine the pharmacological properties of the lead compound and explore of our compound on cooper pathways that leads to oxidative stress and inflammation.

Salt-Induced Diffusiophoresis of a Cationic Micelle in Water. Determination of Cross-Diffusion Coefficients

Type: Graduate
Author(s): Khanh Nguyen Chemistry & Biochemistry Minh Le Chemistry & Biochemistry
Advisor(s): Onofrio Annunziata Chemistry & Biochemistry
Location: FirstFloor, Table 1, Position 1, 11:30-1:30

Salt-induced diffusiophoresis is the movement of a charged nanoparticle in water, driven by an imposed directional gradient of salt concentration. This transport phenomenon has become a valuable tool for manipulating charged nanoparticles within porous materials and microfluidic systems. Micelles are a typical example of nanoparticles with the important ability to host small guest molecules. Therefore, micelle diffusiophoresis is also crucial for manipulating small molecules. This poster reports measurements of diffusiophoresis coefficients carried out on aqueous mixtures of the surfactant, hexadecylpyridinium chloride (CPC) in the presence of NaCl by Rayleigh interferometry. Measurements of NaCl osmotic diffusion from high to low micelle concentration are also reported. We observe that diffusiophoresis of CPC cationic micelles occurs from high to low salt concentration. A model describing the behavior of micelle diffusiophoresis as a function of NaCl concentration is reported. Our diffusiophoresis results are explained in terms of micelle electrical charge, salt osmotic diffusion coefficients and zeta potential. This work offers new insights into diffusiophoresis of charged nanoparticles with potential applications for enhanced-oil recovery from porous rocks, soil remediation and diffusion-based mixing inside microfluidics.

Europium-doped Cerium Oxide Nanotubes as a potential probe for bioimaging and optical sensors

Type: Graduate
Author(s): Leonardo Ojeda Hernandez Chemistry & Biochemistry Kayla Brownell Chemistry & Biochemistry Joseph Chouinard Physics & Astronomy
Advisor(s): Jeffery Coffer Chemistry & Biochemistry
Location: SecondFloor, Table 1, Position 2, 11:30-1:30

The development of cerium oxide (CeO2) nanomaterials is rapidly advancing, driven by their wide range of applications in catalytic converters, solid oxide fuel cells, and biological sensors. Considering this, doping CeO2 with rare earth elements such as Europium (Eu3+) not only enhances its catalytic properties but also adds visible fluorescence to the list. To explore the variability of this effect, Eu3+ doped CeO2 nanotubes were synthesized and carefully analyzed by varying the Eu3+ concentration to investigate their optical properties, crystallinity, and morphology. Current research is focused on evaluating the potential of these doped CeO2 nanotubes as probes for bioimaging and optical sensors.

Unraveling asphaltene aggregation: Computational insights into sticky situations

Type: Graduate
Author(s): Gretel Stokes Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry

Asphaltenes are the heaviest component of crude oil and strongly aggregate during the oil refinement process, fouling equipment and increasing oil runoff. Understanding their propensity for aggregation at the molecular level is crucial for developing strategies to mitigate their role in equipment fouling. Using computational chemistry, we analyzed the dimerization energies of 67 previously published asphaltene structures by running CREST calculations on all possible molecular pairs. Our results reveal that diradical:diradical interactions drive strong aggregation, whereas radical-closed shell interactions are comparable in strength to closed-shell:closed-shell interactions. Additionally, we find that archipelago-type structures weaken dimerization as compared to island-type asphaltenes, likely due to self-association of archipelago structures. These findings provide key insights into asphaltene behavior and suggest potential strategies for disrupting aggregation. Future work will explore whether near-infrared light can be used to disaggregate asphaltenes, offering a novel approach to alleviate asphaltene-related challenges in industry.

Exploring molecular design: A triazine library reveals a surprisingly hydrophobic molecule

Type: Graduate
Author(s): Gretel Stokes Chemistry & Biochemistry Casey Patterson-Gardner Biology
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Third Floor, Table 4, Position 1, 1:45-3:45

Macrocycles are promising drug candidates due to their ability to selectively interact with biological targets. However, predicting their solubility and membrane permeability remains challenging. To probe this, a library of 35 triazine macrocycles was synthesized and the hydrophobicity of each macrocycle was measured using octanol:water partition coefficients (logP).

Unexpectedly, a glycine-derived macrocycle with two primary amine groups displayed high hydrophobicity, contrary to prediction based on conventional computational methods for computing logP (AlogP). Computational analysis revealed that the diamine substitution stabilizes a closed conformation, tethering the macrocycle where its polar groups are shielded from solvent interaction, thus increasing hydrophobicity. Additionally, we found that logP values of heterodimer macrocycles closely approximated the average of their corresponding homodimers, suggesting a predictable trend in partitioning behavior.

We demonstrate how small molecular changes can significantly impact physical properties. By combining synthesis, physical measurements, and computational modeling, our work provides insights into macrocycle behavior that could aid in designing membrane-permeable drug candidates.

Assessing the Impact of Land Use Change on Water Quality in Lake Worth, Texas

Type: Graduate
Author(s): Portia Asare Environmental Sciences
Advisor(s): Environmental Sciences Esayas Gebremichael Geological Sciences
Location: SecondFloor, Table 7, Position 3, 11:30-1:30

Rapid urbanization in the Dallas-Fort Worth metropolitan area is increasing pressure on water resources, including Lake Worth. This project will investigate the relationship between land use, land cover change, and water quality degradation in Lake Worth, a reservoir facing increasing development pressure near Fort Worth. The project will use historical land data to quantify land use/land cover change (LULC) within the watershed between 2000 and 2023. This land use data will be integrated with the publicly available water quality data (nutrients, dissolved oxygen, pH, turbidity) from the Surface Water Quality Monitoring Program and locations of permitted industrial discharge points from the Texas Commission on Water Quality. GIS techniques, including spatial joins, buffer analysis, and statistical modeling (regression, hotspot analysis), will be used to analyze the correlation between LULC and water quality parameters and identify pollution hotspots. The expected outcomes include detailed land use maps, a geodatabase of water quality and discharge points, statistical models quantifying the land use-water quality relationship, and identifying areas requiring management intervention. The study's findings will inform land use planning, water resource management, and sustainable urban development practices in the region while acknowledging limitations related to data availability, spatial resolution, causality, and model generalizability.

The Effect of Urban Development-Driven Tree Removals on Land Surface Temperature in a Growing City

Type: Graduate
Author(s): Hannah Buckhalter Environmental Sciences
Advisor(s): Brendan Lavy Environmental Sciences

Development and Socioeconomic Drivers of Permitted Tree Removals in Austin, Texas

Type: Graduate
Author(s): Adam Buckmeier Environmental Sciences
Advisor(s): Brendan Lavy Environmental Sciences
Location: Basement, Table 9, Position 2, 1:45-3:45

In urban environments, trees provide a range of services including pollution removal, temperature regulation, and increased property values. In an effort to accrue these services, municipalities enact tree preservation ordinances that seek to protect public and private trees. Despite the protections of these ordinances, many trees are removed legally each year due to urban (re)development, risks associated with tree growth, and tree death. This research examines the spatiotemporal trends of permitted tree removals in the City of Austin, Texas, from 2013 to 2023. Specifically, we created a geographic information system to explore the differences between development-related and non-development-related removals, as well as between healthy and unhealthy removals. We also explored the extent to which sociodemographic characteristics explained differences in tree removals. Preliminary findings reveal that most trees removed are healthy and for development-related reasons, a reflection of Austin’s accelerating urban growth. We identified areas with high to moderate development pressure, high health impacts, and low activity. Our analysis also revealed significant patterns in tree removals associated with demographic and socioeconomic characteristics. Areas with higher proportions of non-White populations experience fewer tree removals. This, however, correlates with lower overall canopy cover, suggesting these areas have fewer trees to begin with. Conversely, neighborhoods with higher household incomes show more tree removals but also higher canopy cover, indicating more active tree management in wealthier areas with greater tree resources. Our research highlights location-specific tree removal patterns to inform strategies that account for both environmental and socioeconomic factors.