A Six-Factor Model of Ethical Decision-Making

Type: Graduate
Author(s): Kevin Diegel Psychology
Advisor(s): Timothy Barth Psychology
Location: Third Floor, Table 3, Position 1, 11:30-1:30

This study examines the integration of Care ethics as a distinct factor into the Ethical Perspectives Scale (EPS; Diegel et al., 2024). In contrast to typical ethical theories centering on consequentialist, deontological, and virtue ethics reasoning, Care ethics prioritizes relational and situationally appropriate moral judgment. In the conduct of four experimental studies, we made Care an independent factor by utilizing Exploratory and Confirmatory Factor Analyses, assessed its predictive validity regarding moral dilemmas, tested its temporal stability, and generalized the findings to a population outside of the student group.

Results confirmed that Care ethics is conceptually and statistically distinct from Virtue ethics, predicting moral judgments in relational and compassion-based contexts. Care ethics correlated with political ideology, religiosity, and subjective well-being, further differentiating it from other ethical dimensions. However, ethical decision-making remained highly context-dependent, with different perspectives becoming salient across dilemma types.

The findings of this research promote the integration of Care ethics into models of moral decision-making, thus highlighting its relevance to practical uses. Future studies should examine its applicability in various cultures and its impact on professional ethics training.

Impact of food insecurity on anxiety-like behavior and spatial memory in old-age C57BL/6J mice

Type: Graduate
Author(s): Logun Gunderson Psychology Morgan Bertrand Biology Gabriella Dover Biology Faith Harms-Zacharias Psychology Katie Robb Psychology
Advisor(s): Gary Boehm Psychology Michael Chumley Biology
Location: Third Floor, Table 8, Position 2, 1:45-3:45

Food insecurity affects more than 6 million households with children in the U.S., the majority of which are insecure without hunger. Food insecurity and the accompanying chronic unpredictability are associated with significant negative health outcomes, such as impaired immune function, anxiety/eating disorders, malnutrition, and delayed language acquisition. To explore the connection between the unpredictability of a food source and cognitive impairments, prior studies have attempted to model food insecurity in rodent models. An ideal study design to answer this question would expose mice to a truly unpredictable food source for an extended period and assess their behavior for any significant changes, but most of the prior work has not been able to make a truly unpredictable food source which limits the generalizability of their findings. To address these limitations, the present study aimed to ensure that the rodent's food source was truly unpredictable by randomly assigning periods of limited food access across each week of the study. 18-month-old male and female C57BL/6J mice were either given ad libitum food access or were food insecure, where their otherwise full food-hopper would be reduced to 25% of their baseline consumption two randomly selected nights each week until the following morning. At 21 months, the mice underwent a battery of behavioral tests, including the open field test, elevated-zero maze, and novel object location task, to assess anxiety-like behavior and spatial memory capabilities. While insecurely-fed male mice were trending towards displaying more anxiety-like behavior than their securely-fed counterparts, we found no significant impact of food insecurity on anxiety-like behavior or spatial memory capabilities. Taken together, this study provides a more complete analysis of the behavioral changes due to a truly unpredictable food source, which more closely represents the environment of those living with food insecurity, and highlights areas to improve the model for future investigations.

Histological analysis of peripheral tissues following Typical American (TAD) or Mediterranean (MD) diet consumption in C57BL/6J mice.

Type: Graduate
Author(s): Faith Harms-Zacharias Psychology Skye Duncan Biology Sara Gabriel Biology Ashish Rana Psychology
Advisor(s): Gary Boehm Psychology Michael Chumley Biology
Location: SecondFloor, Table 5, Position 1, 11:30-1:30

At least 6.9 million Americans aged 65 and above are living with Alzheimer’s disease (AD) as of 2024, and that number is only expected to increase as the aging population grows. The exact cause of AD has yet to be discovered, but there are several significant risk factors such as sleep deprivation, a lack of exercise, and diet quality. Our lab has investigated diet quality in relation to AD pathology through the creation of two representative diets, the Typical American Diet (TAD) and the Mediterranean Diet (MD). These diets are calorically matched and are used to investigate their long- and short-term effects on Alzheimer’s pathology in C57BL/6J mice. To follow up on a previous study that used 6 months of diet exposure to explore the longer-term effects of these diets, groups of mice were fed either the TAD or MD for 3 months, beginning at 4 months of age, to better understand the short-term effects. This project then conducted histological analysis on the colon, liver, and gonadal white adipose tissue using different histological techniques. Specifically, a cryostat and microtome were used to prepare the tissue samples, and they were stained using Hematoxylin and eosin (H&E) staining and Oil Red O. Samples were then examined using confocal microscopy, and tissues from each diet were compared and analysed. We found that 3 months of diet led to excess hepatic lipid deposition, as was found in the 6-month study. Additionally, the 6-month study suggested that the TAD may have induced an insulin resistance (IR) state, so gonadal white adipose tissue was examined to explore adipocyte expansion after 3 months on diet. Preliminary colon histology was conducted to begin the exploration into gut dysbiosis and inflammation and the connection to Alzheimer’s pathology. This study presents novel histological evidence of the impact of diet quality on peripheral tissue in relation to Alzheimer’s disease.

Increasing Access to PrEP for Women of Color by Leveraging Beauty Shops as Community Health Hubs with Women's Healthcare Delivery: The Beauty Shop Study

Type: Graduate
Author(s): Savannah Hastings Psychology Pam Carey Psychology Sarah Gonzalez Psychology McKynzie Johnson Psychology Randi Proffitt Psychology Stephanie Villaire Psychology
Advisor(s): Kevin Knight Psychology
Location: Basement, Table 8, Position 2, 1:45-3:45

Each year, Black women are disproportionately affected by new HIV diagnoses. Recent data of HIV cases in Texas indicate that approximately 56% of new HIV cases in women occur in Black women, despite them making up only 13% of the female population in the state. This stark disparity highlights the need for targeted interventions that address the barriers to accessing sexual health resources, including HIV prevention services. The Beauty Shop Study seeks to address these gaps by leveraging beauty professionals as trusted community health advocates (CHAs). These CHAs facilitate sexual health conversations and connect clients with essential healthcare services. This study evaluates the effectiveness of the two combined interventions: (a) using beauty shops as community health hubs and (b) providing healthcare through either a mobile health unit (MHU) or a referral coordinator. Participants engage in three visits with a research assistant across 6 months, which include interviews and specimen collection. In Tarrant County, participants have access to a MHU for 3 months, while in Dallas County, participants receive support from referral coordinators for the same duration. Recruitment for the present study presented several challenges, including the ineffectiveness of virtual training for CHAs and the inability to accept snowball referrals. However, outreach efforts strengthened trust, ultimately increasing referrals and community engagement. Moving forward, insights from this pilot study will inform the development of future iterations of the project. The findings will continue to advancing community-centered approaches that enhance Black women’s access to sexual health care.

Comparing Different Methods for Assessing Substance Use Post-Release Among Justice-Involved Youth

Type: Graduate
Author(s): Brianna Pitz Psychology Danica Knight Psychology Kevin Knight Psychology Yang Yang Psychology
Advisor(s): Yang Yang Psychology
Location: Third Floor, Table 5, Position 2, 1:45-3:45

Substance use is a pervasive issue in adolescents, and justice-involved youth are at a heightened risk of SU compared to the general youth population. Monitoring individual SU trajectory such as initiation, escalation of use, progression, and reductions is important for identifying key prevention and intervention opportunities. There are tools to assess SU in youth populations, but little research has been conducted to compare these assessments in terms of how they accommodate sporadicity of SU within various time frames. This study compared two self-reported measures for post-release SU—Timeline Follow-Back (TLFB) and Substance Use Involvement Scale (SUIS)—within youth who were recently released from secure residential facilities. The aims of this study are to examine the differences between TLFB and SUIS in (1) alcohol and cannabis use (yes/no), (2) the cumulative number of days of alcohol and cannabis use, and (3) the average daily use frequency for youth who have initiated alcohol and cannabis use post-release. This study used a subsample of 89 youth who reported post-release SU. Results revealed that (1) SUIS reported significantly greater number of youth that indicated alcohol and cannabis use (ps ≤ .001) than TLFB, (2) SUIS and TLFB did not differ in cumulative number of days of cannabis use (p = .40), but SUIS recorded a significantly greater number of days of alcohol use than TLFB (p ≤ .001), and (3) SUIS reported significantly greater average frequency of use per day for both cannabis and alcohol use (ps ≤ .001) compared to TLFB. TLFB provided more in-depth results for individual participants’ SU patterns including date of initiation post-release and day-by-day frequencies of use compared to SUIS. Despite TLFB’s advantages, additional strategies are needed to optimize the intensive process of data capturing and to support the external validity for capturing long-term SU. SUIS adequately captured data for sporadic SU without an overwhelming amount of data that worked well for comparing broad patterns of SU. These findings collectively show the importance of TLFB and SUIS measures in addressing different research goals.

Bleeding Votes: The power of period imagery in politics.

Type: Graduate
Author(s): Bao Han Tran Psychology Cathy Cox Psychology
Advisor(s): Cathy Cox Psychology
Location: Basement, Table 13, Position 1, 1:45-3:45

Menstruation is stigmatized in many areas of society, often leading to distancing behavior and increased objectification of women. This is commonly reflected in the widespread use of euphemisms, or metaphors, for menstruation. According to conceptual metaphor theory, a society is shaped by the metaphors it adopts. When menstruation metaphors are used in a political context, it raises questions about whether their harmful connotations affect political appeal and broader societal implications. This study explores the power of menstrual metaphors in political attack ads, specifically focussing on the “Tampon Tim” campaign. Participants were randomly assigned to view one of three political ads (i.e., metaphor, non-metaphor, and neutral) and answer questions about ad appeal and individual differences. Results support our hypothesis that menstruation metaphors influence political opinions.

Increasing PrEP Access for Black Women: The Role of Beauty Professionals in HIV Prevention Education

Type: Graduate
Author(s): Stephanie Villaire Psychology Sakina Ghafoor Psychology Savannah Hastings Psychology Quinceola Reid Psychology
Advisor(s): Kevin Knight Psychology Pamela Carey Psychology Randi Proffittt Psychology
Location: Basement, Table 6, Position 2, 11:30-1:30

Among women in Texas, Black women account for 56% of new HIV infections. However, Black individuals receive only 14% of prescriptions for PrEP, a medication that prevents HIV transmission. In an effort to increase PrEP uptake among Black women, the Beauty Shop Study engages beauty professionals as trusted community members, equipping them to provide sexual health education to their clients. Clients are then connected with the TCU Mobile Health Unit for service delivery and/or referral coordination. In the initial phase, the study collected Beauty Shop Study needs assessment data from 32 beauty professionals in North Texas, exploring their experiences discussing sexual health and related topics with their clients. The current study will present these findings to highlight community readiness and the importance of the Beauty Shop Study.

Native Grassland Stewardship: An Archetype for Sustainable Management

Type: Graduate
Author(s): Riley O'Connor Ranch Management Brooke Best Ranch Management Kelton Eason Ranch Management Jeffrey Geider Ranch Management Ashley Titus Ranch Management
Advisor(s): Jeffrey Geider Ranch Management
Location: Third Floor, Table 10, Position 2, 11:30-1:30

Native Grassland Stewardship: An Archetype for Sustainable Management

Fort Worth, Texas, encompasses two significant tallgrass prairie ecosystems: the Blackland Prairie and the less-studied Fort Worth Prairie. Currently, less than 1% of these prairies remain due to escalating urban expansion, unsustainable agricultural practices, and the growth of the energy sector (Robison et al., 1995). With over 93% of Texas land under private ownership, effective conservation strategies must inclusively engage all stakeholders, notably land managers (Texas Parks and Wildlife, 2025). This study aims to develop a comprehensive management plan for the native prairie ecosystem located within the Botanical Research Institute of Texas at the Fort Worth Botanic Garden. The proposed plan is designed to act as an archetype for regeneratively managed prairies and ranches.
Field methodologies encompassed a detailed vegetation survey, forage-clipping analyses, and identification of dominant species. From an ecological perspective, this research emphasizes the critical role of adaptive management in restoring native ecosystems, fostering responsible land stewardship, and promoting public engagement in grassland conservation. The findings aim to contribute practical insights for landowners, conservationists, and policymakers dedicated to preserving and sustainably managing tallgrass prairies in North Texas.

Keywords: Prairie Conversation, Adaptive Management, Sustainable Grazing, Ranch Management

References
Robison, R., White, D. B., & Meyer, M. H. (1995). Plants in Prairie Communities. St. Paul, MN: University of Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/93930.
Texas Parks and Wildlife. (2025). Private Landowners and Listed Species. https://tpwd.texas.gov/wildlife/wildlife-diversity/nongame/listed-species/private-landowners-and-listed-species/

Type: Graduate
Author(s): Ashley Titus Interdisciplinary
Advisor(s): Ranch Management

Type: Graduate
Author(s): Ashley Titus Interdisciplinary
Advisor(s): Ranch Management

Visualizing the Structural Effects of Proline Variants on the BRCA1-PALB2 Binding Interface

Type: Graduate
Author(s): Chrissy Baker Biology Sergei Dzyuba Chemistry & Biochemistry Mikaela Stewart Biology
Advisor(s): Mikaela Stewart Biology
Location: Basement, Table 11, Position 1, 11:30-1:30

Both Breast Cancer Gene 1 (BRCA1) and Partner and Localizer of BRCA 2 (PALB2) interact through their coiled-coil domains and are critical for proper functioning of DNA repair through homologous recombination. Individuals who carry pathogenic variants in either protein have an increased risk of developing breast cancer. Multiple variations of unknown significance (VUS) have been documented within the coiled-coil region of each protein, meaning a person carries a variation in either BRCA1 or PALB2 but there is not enough data to know the clinical significance of those variants. In this study, we analyzed the structural effects of five proline VUS within the binding region of BRCA1 and PALB2, three variants that have been discovered in patients and two variants that have not yet been discovered in patients. We used a known benign valine variant and a known pathogenic proline variant as our negative and positive controls, respectively. Because proline variants are known to disrupt protein structure, we hypothesize the proline variants will inhibit coiled-coil formation and, in turn, disrupt interaction between BRCA1 and PALB2. Each coiled-coil construct was generated in vitro and its structure analyzed using circular dichroism first individually and then in the presence of its wild-type binding partner. While all proline variants affected the structure of BRCA1, they had different degrees of impact depending on where they are located in the coiled-coil. This suggests that proline variants impact the ability of BRCA1 to form a coiled-coil in the presence of PALB2 and may be pathogenic. Notably, however, the BRCA1 proline variants seem to cause different structural changes from the pathogenic PALB2 proline variant. This prompts further research to determine the structural effects on the residue level and to correlate structural changes with functional changes.

Ability of diet to induce heritable epigenetic modifications associated with Alzheimer's disease

Type: Graduate
Author(s): Bridey Brown Biology Asher Smith Biology
Advisor(s): Matt Hale Biology
Location: First Floor, Table 2, Position 1, 1:45-3:45

Alzheimer’s disease (AD) is a neurodegenerative disease that is the most common cause of dementia. There is currently no cure for AD, which means the best alternative is developing preventative strategies, such as adoption of the Mediterranean diet (MD), which has been shown to reduce risk of AD development and mortality. In comparison, a typical American diet has been shown to increase risk of AD development. Although the ability of dietary factors to alter the propensity of development of AD is well established, the mechanisms through this is mediated is unknown. One largely unexplored mechanism of dietary-induced AD prevalence is epigenetic modification to genes associated with AD. The most studied epigenetic modification, DNA methylation of cytosines, has been known to alter gene expression levels. Therefore, this study aims to determine whether dietary influences can induce epigenetic modifications, and subsequently modify expression of genes associated with AD. To do this, DNA was extracted from hippocampal tissue of mice on either a MD or TAD, as well as their offspring who were consuming a control diet. The offspring were included to determine if differential methylation patterns are heritable, thereby implicating transgenerational effects and predisposition to AD development or protection. An epigenetic array was used to identify loci that were differentially methylated between diets, and qPCR was used to determine if differential methylation resulted in significant differences in gene expression. No loci were found to be significantly differentially methylated (p-val<0.0001) with an effect size of 10% or more, nor differentially expressed upon qPCR analysis.

Zinc Oxide Nanoparticles Mediate Bacterial Toxicity in Mueller-Hinton Broth via Zn2+

Type: Graduate
Author(s): Alexander Caron Biology Iman Ali Biology Michael Delgado Biology Dustin Johnson Physics & Astronomy Yuri Strzhemechny Physics & Astronomy
Advisor(s): Shauna McGillivray Biology
Location: Second Floor, Table 4, Position 3, 11:30-1:30

As antibiotic resistance increases and antibiotic development dwindles, new antimicrobial agents are needed. Recent advances in nanoscale engineering have increased interest in metal oxide nanoparticles, particularly zinc oxide nanoparticles, as antimicrobial agents. Zinc oxide nanoparticles are particularly promising due to their broad-spectrum antibacterial activity and low production cost. Despite many studies demonstrating the effectiveness of zinc oxide nanoparticles, the antibacterial mechanism is still unknown. Previous work has implicated the role of reactive oxygen species such as hydrogen peroxide, physical damage of the cell envelope, and/or release of toxic Zn2+ ions as possible mechanisms of action. To evaluate the role of these proposed methods, we assessed the susceptibility of S. aureus mutant strains, ΔkatA and ΔmprF, to zinc oxide nanoparticles. These assays demonstrated that hydrogen peroxide and electrostatic interactions are not crucial for mediating zinc oxide nanoparticle toxicity. Instead, we find that a soluble factor accumulates in Mueller Hinton Broth over time that mediates toxicity and that removal of Zn2+ through chelation reverses this toxicity. Furthermore, we find that the physical separation of zinc oxide nanoparticles and bacterial cells using a semi-permeable membrane still allows for growth inhibition. We conclude that soluble Zn2+ is the primary mechanism by which zinc oxide nanoparticles mediate toxicity in Mueller Hinton Broth. Future work investigating how factors such as particle morphology (e.g., size, polarity, surface defects) and media contribute to Zn2+ dissolution could allow for the synthesis of zinc oxide nanoparticles that possess chemical and morphological properties best suited for antibacterial efficacy.

Using Targeted Poisoning of Red Imported Fire Ants to Improve Texas Horned Lizard Habitat

Type: Graduate
Author(s): Kira Gangbin Biology Rachel Alenius Biology Diane Barber Biology Mark Mitchell Biology Nathan Rains Biology Madison Upton Biology Dean Williams Biology
Advisor(s): Dean Williams Biology
Location: Basement, Table 9, Position 2, 1:45-3:45

The spread of red imported fire ants (Solenopsis invicta; RIFA) has frequently been cited as a factor contributing to the decline of the Texas horned lizard (Phrynosoma cornutum; THL). Two hypotheses for this are: 1) direct lizard mortality due to RIFA, and 2) displacement of THL’s main food source, harvester ants (Pogonomyrmex spp.), by RIFA. A new third hypothesis suggests that the invasion of RIFA could be causing a decline in hatchling THL food resources, as their diet is mainly composed of small ant species. Many studies have attempted widespread treatment to eradicate RIFA; however, this could have unintended consequences for non-target ant species that THL depend on. Using a targeted application method, we sought to reduce RIFA populations over the summers of 2022 and 2023 at four sites located at Mason Mountain Wildlife Management in central Texas, a locality with an ongoing THL reintroduction program. At each site, hot dog baits were placed 5 meters apart in 10x10 grids. At treatment sites, one teaspoon of Amdro (a common ant poison) was applied to baits with RIFA thirty minutes after placement. After Amdro was applied, baits were left for 30 minutes and then collected. Treatments were repeated monthly May – August. The effects of each targeted poisoning were evaluated using pitfall traps and ant abundance measurements from baits. Results showed that treatment may have decreased RIFA abundance for both years and had variable effects on hatchling food abundance. Future studies will increase sample size to better detect potential treatment effect.

Long-term consumption of a typical American diet promotes hepatic lipid deposition and soluble amyloid-beta in the brain, in comparison to a Mediterranean diet

Type: Graduate
Author(s): Vivienne Lacy Biology Morgan Bertrand Biology Paige Braden Kuhle Biology Isaac Mills Biology Fabiana Pulido Biology Ashish Rana Biology
Advisor(s): Michael Chumley Biology Gary Boehm Psychology
Location: Basement, Table 14, Position 2, 11:30-1:30

Approximately 1 in 9 Americans over the age of 65 has Alzheimer’s disease (AD). As the size of this age group is expected to more than double by 2040, the AD prevalence is likewise predicted to increase rapidly. Two key risk factors for late-onset AD include poor diet and obesity. Therefore, long-term nutritional strategies could potentially reduce the development of hallmark AD biomarkers, such as amyloid beta (Aβ), later in adulthood. Researchers have found that diets extremely rich in saturated fats are associated with increased Aβ production in both the cortex and hippocampus of rodents. Conversely, plant-based Mediterranean diets (MD) that are plentiful in unsaturated fatty acids were shown to mitigate Aβ in rodents.

The relationship between diet and AD biomarkers has been explored in prior animal research, yet most studies utilize extremely high fat diets (40-60% kcal fat) or supplement with individual MD nutritional components. To address these limitations, we designed comprehensive, macronutrient-matched Mediterranean and typical American diets (TAD) that mimic human diets in Mediterranean regions and the U.S., respectively. C57BL/6J mice were weaned onto one of the two diets at postnatal day 21. Following 6 months of diet consumption, we found that the TAD increased soluble Aβ1-42 in the brain. Additionally, mice on the TAD had excess hepatic lipid deposition, which is a hallmark of insulin resistance and metabolic dysregulation, a comorbidity linked to AD risk.

Employing a New Testing Method for Identifying Fluridone Resistance in Hydrilla

Type: Graduate
Author(s): Ulysses Oles Biology
Advisor(s): Dean Williams Biology
Location: Basement, Table 1, Position 1, 1:45-3:45

Hydrilla verticillata is an invasive aquatic plant found in freshwater systems throughout the United States. Invasions pose a threat to plants and animals that come into contact with the rapidly expanding hydrilla, and recreational activities such as fishing and boating are disrupted when densely packed mats of vegetative material form near the surface of the water. These invasions have historically been controlled using the herbicide fluridone, but resistant hydrilla populations have emerged with mutations in the pds gene associated with the production of phytoene desaturase. These resistant mutant plants are outwardly indistinguishable from the susceptible wildtype, and as such it can be challenging for aquatic systems managers to identify whether or not fluridone can be considered as an effective treatment option without some form of genetic testing. The existing standard process for identifying resistant mutants is a lengthy process that relies on amplifying and sequencing the pds gene. Our work has sought to utilize the process of double-mismatch allele-specific qPCR (DMAS-qPCR) to create a quicker and more cost-effective tool to aid in understanding the extent of fluridone resistant hydrilla. Having designed sets of primers specific to the mutations found within the pds gene, the next step is to apply this method to screening hydrilla samples from a variety of geographies in order to outline the spread of the resistant mutant populations.

Role of MsrB in Cell Envelope Antimicrobial Tolerance in Bacillus anthracis Sterne

Type: Graduate
Author(s): Aeron Pennington Biology Salina Hona Biology Shauna McGillivray Biology Kelsey Waite Biology
Advisor(s): Shauna McGillivray Biology
Location: Third Floor, Table 3, Position 1, 1:45-3:45

The prevalence of antimicrobial-resistant bacteria is a rapidly growing public health crisis. This, combined with a decline in the development of novel antimicrobial therapies, makes the search for unique drug targets essential. Previous work from our lab has identified a promising antimicrobial drug target within Bacillus anthracis, the regulatory ATPase, ClpX. ClpX is essential for virulence in B. anthracis and critical for resistance to a host of cell envelope-targeting antimicrobials. ClpX works with ClpP to form a global protease that regulates a wide range of proteins, including transcriptional regulators. Previously, we conducted a microarray of a ΔclpX mutant and found 119 genes with altered expression. One such gene, msrB, has been studied for reactive oxygen species tolerance in other pathogens. This gene encodes for methionine sulfoxide reductase, an antioxidant enzyme that restores functionality to oxidized methionine residues. Increased msrB expression was seen with oxacillin exposure in S. aureus, indicating a potential connection between MsrB and cell wall-targeting antimicrobials. In B. anthracis Sterne, loss of msrB induces sensitivity to penicillin, but unlike ΔclpX, this phenotype is not seen with daptomycin or LL-37. This suggests that the role of msrB in antimicrobial tolerance may be limited to cell wall active antibiotics. Further experiments will include testing the ΔmsrB mutant with additional cell wall-specific antimicrobials (e.g., bacitracin and vancomycin). Our research provides additional information regarding the role of MsrB in the bacterial cell and its potential suitability as a pharmacological target to increase susceptibility to antibiotics.

Assessing extinction risk for a group of neotropical ferns

Type: Graduate
Author(s): Lucia Vargas Biology
Advisor(s): Matt Hale Biology Alejandra Vasco Biology
Location: Second Floor, Table 5, Position 1, 1:45-3:45

Understanding the diversity and distribution of species on Earth is crucial in the face of contemporary threats to biodiversity, such as climate change and unsustainable economic practices. Unfortunately, the process of documenting and describing biodiversity often cannot keep pace with habitat loss and species extinction, especially in tropical regions where the number of undescribed and poorly known species is highest, and where biodiversity is most severely threatened. If this diversity is not documented, it will mean a loss of valuable understanding of the natural world and a failure to recognize species whose societal values remain undiscovered or underappreciated. This research will assess the extinction risk of selected fern species to understand their conservation status. The focus lies on understanding the classification, distribution, and conservation status of a group of species within the fern genus Elaphoglossum, the Elaphoglossum dendricola Clade, consisting of around 12 species distributed in the Tropical Andes, mostly at high altitudes (over 2400 m). This assessment aims to serve as a baseline for future conservation studies of this neotropical group of ferns.

Temporal Analysis of Mercury Levels and Stable Isotope Dynamics in Seabirds of Northwest Greenland

Type: Graduate
Author(s): Kimberlee Whitmore Biology Matt Chumchal Biology
Advisor(s): Matt Chumchal Biology
Location: First Floor, Table 6, Position 2, 11:30-1:30

Due to widespread anthropogenic emissions and a global atmospheric cycle, mercury contaminates all aquatic ecosystems, including in the Arctic, at concentrations above pre-industrial baselines. Many seabirds nest in large colonies in the Arctic and are at elevated risk of mercury contamination due to their planktivorous and piscivorous diets and long lifespan. We investigated temporal trends of mercury contamination in five species of seabirds from northwest Greenland. Blood samples were collected regularly since 2010 from adult Atlantic puffins (Fracterula arctica), black guillemots (Cepphus grylle), black-legged kittiwakes (Rissa tridactyla), dovekies (Alle alle) and thick-billed murres (Uria lomvia). Samples were analyzed for total mercury using direct mercury analysis. All species had average blood mercury concentrations between 212 and 769 ng/g-wet weight, concentrations associated with a low risk for mercury toxicity. Individual black guillemots and thick-billed murres had blood mercury concentrations >1,000 ng/g wet weight, concentrations associated with moderate risk for mercury toxicity. Preliminary analyses suggest an overall increase in mercury concentrations in black-legged kittiwakes, dovekies and thick-billed murres over the study period. Comparable temporal studies in the Arctic have shown wide variation in mercury contamination trends. The results of the present study contribute to the understanding of regional mercury trends in the Arctic and efforts to assess the impact of the Minamata Convention.

Investigation of Charge Transfer Between Porous Silicon and Metal Halide Perovskites

Type: Graduate
Author(s): William Burnett Chemistry & Biochemistry Bong Lee Physics & Astronomy
Advisor(s): Jeffery Coffer Chemistry & Biochemistry Ignacy Gryczynski Physics & Astronomy Zygmunt Gryczynski Physics & Astronomy
Location: Third Floor, Table 5, Position 1, 1:45-3:45

Silicon-Perovskite tandem solar cells are some of the leading emerging technology solar cells due to their high photoconversion efficiency or the ability to turn light into electricity. These solar cells rely on the ability to harvest a higher percentage of the solar spectrum due to the differences in the two materials. MHPs are an ionic crystal that have the chemical formula ABX3 where A is a monovalent cation (+1) such as cesium, methylammonium or formamidinium; B is a divalent cation (+2) such as lead or tin, and X is a halide such as chloride, bromide, or iodide. Porous silicon is crystalline silicon that has been etched to form pores with properties dependent upon the etching conditions. Porous silicon that has been etched such that the silicon area between the pores is between 1-4nm becomes photoluminescent (PL). It has been shown that the optoelectronic properties of metal halide perovskite (MHPs) grown within porous silicon (pSi) are highly dependent upon the surface area, pore size, and surface chemistry of the pSi. This interaction has led us to investigate the fundamental interactions that occur when nanoscale porous silicon encounters nanoscale MHP, namely the possibility of energy/charge transfer.
We have evaluated two different experimental designs. The first entails adsorbing ligand passivated MHP quantum dots onto a solid piece of luminescent mesoporous Si membrane and allow the solvent to evaporate. The change in luminescence from the pSi can be used to monitor the impact the perovskite has upon the pSi by monitoring the change in intensity and wavelength. The second approach as previously described utilizes MHP quantum dots (QDs) dispersed in toluene which is then titrated with non-luminescent pSi and the PL monitored. The primary impact of the pSi upon the light emission of the perovskite QDs is a significant reduction in the intensity of the emission. Comparisons of different pSi with hydride terminated versus oxide terminated surfaces show a dependence upon the surface chemistry to the change in PL. The PL lifetimes will be measured, and comparisons made to determine the mechanism of energy transfer.

New Approaches to Macrocycle Synthesis

Type: Graduate
Author(s): Liam Claton Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Second Floor, Table 1, Position 2, 11:30-1:30

Creating a diverse array of structurally distinct, triazine-containing, macrocycles remain the focus of the Simanek group. Until now, this goal has been accomplished through a straightforward 3 step synthetic route with variation of amino acid incorporation and acetal length. Currently two new approaches to macrocycle synthesis are being pursued. The first approach relies on two like monomers coming together: by changing the relative position of groups in the macrocycle, the persistence of shape can be probed. The second approach relies on two different monomers coming together. Using a similar synthetic route, this strategy, if successful, will allow much finer control over design and engineering these molecules for specific purposes. These libraries of structurally diverse macrocycles are important for the long-term goals of establishing rules that can guide pharmaceutical drug design in these under-explored types of molecules.

Anti-Oxidant Ligand Mimics

Type: Graduate
Author(s): Nora Del Bosque Chemistry & Biochemistry Kayla Green Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Basement, Table 11, Position 2, 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.

Impact of Selected Ionic Liquids on the Properties of Metal Halide Perovskites

Type: Graduate
Author(s): Maegyn Grubbs Chemistry & Biochemistry Sergei Dzyuba Chemistry & Biochemistry
Advisor(s): Jeff Coffer Chemistry & Biochemistry
Location: Basement, Table 8, Position 1, 11:30-1:30

Metal-halide perovskites are crystalline materials that work as a semiconductor in both Light Emitting Diodes (LEDs) and solar cells. In general, perovskites possess the formula ABX3. For this project, the A site is an organic molecule such as Methylammonium (MA), the B site is Lead, and the X site is Bromide. While perovskites are easily fabricated, their crystal size and number of defects present are challenging to control. Defects cause LEDs to be less stable and/or less photoluminescent (bright) and cause solar cells to be less efficient at converting light to energy. One approach to reduce the number of defects is to use ionic liquids during perovskite formation. Ionic liquids are compounds made of ions in the liquid state due to a low melting temperature. They can be added to the perovskite precursor solution to slow down the crystallization process so that fewer defects are created. The goal of this project is to create new metal halide perovskites in the presence of selected ionic liquids, evaluate their structure and photophysical properties, with the long-term goal of creating new LEDs that are both stable and efficient.

In this project, cetyl-ionic liquids (cetyl meaning 16 carbon chains) were investigated for their effects on perovskite structure and light emission. The three ionic liquids were investigated: [C16-mim]Br (referred to as "IL1"), [C16-py]Br ("IL2"), [C16-C1pyrr]Br ("IL3"), and CTAB (“IL4”). Variations in the deposition method of the perovskite films were studied as well. It was hypothesized that the inclusion of cetyl-ionic liquids will protect the perovskite films from the environment (increasing stability) by providing a hydrophobic layer on the surface and will improve the electronic properties by filling in pinholes that cause defects. It is found that perovskite films with IL1 produced through a two-step spin coat deposition method are more photoluminescent than the perovskite films formed with IL2, IL3, IL4 or no IL (control). These results, along with detailed structural characterization of a given perovskite film, will be discussed in this presentation.

From Macroscopic to Molecular: Investigating the Behavior of Self-Assembling Hinges

Type: Graduate
Author(s): Alexander Menke Chemistry & Biochemistry
Advisor(s): Eric simanek Chemistry & Biochemistry
Location: First Floor, Table 2, Position 1, 11:30-1:30

Hinges are pervasive in the world today. Most common is a simple mortise door hinge  - defined by the flush stacking of leaves and fully revolute motion. Chemists have long sought to reproduce such structures on the molecular scale. Here, the hinge behavior of large, cyclic molecules is described.  Moreover, hinge motion can be controlled by "gumming up" the parts responsible for motion. While dirt and debris work in the macroscopic world, additional atoms are used in these molecular mimics. Specifically, by increasing the size of groups in the hinge domain, the rate of hinging decreases. Hinge motion is visualized by variable temperature NMR spectroscopy where in, at low temperatures the hinging both faces of the leaves (inside and outside) can be observed. At high temperatures, the hinging speeds up and the inside and outside exchange too quickly to be observed. Unlike hinges of everyday use that require human assembly, the molecular hinges described here assemble themselves. As a result, hinges with identical leaves as well as hinges with mismatched leaves can be prepared. Surprisingly, the results of this assembly process are biased: a statistical distribution of hinges is not observed.  Further studies to understanding this steric (gumming) sorting are ongoing.

SURFACE MODIFIED PLATINUM NANOCRYSTAL-BASED SILICON NANOTUBES FOR ENHANCED CANCER CELL TARGETING

Type: Graduate
Author(s): Leonardo Ojeda Chemistry & Biochemistry
Advisor(s): Jeffery Coffer Chemistry & Biochemistry
Location: Third Floor, Table 1, Position 3, 11:30-1:30

Platinum nanocrystals on Silicon nanotubes (PtNCs-pSiNT) exhibit significant anticancer activity via an apoptotic mechanism. To enhance the specificity of this material, we attach folic acid (FA) to the nanotube surface to target folate receptors (FARs) overexpressed in cancer cells. This conjugation is successfully demonstrated through X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT IR). Cell viability assays show an enhanced cytotoxicity toward HeLa cells relative to its non-FA containing analog.

Platinum-based therapeutics, exemplified by the FDA-approved anti-cancer drug cisplatin, are a mainstay in treatment of a range of different cancer types.3 Although this drug can form an adduct with DNA and induce apoptosis, many studies have confirmed that cancer cells can develop resistance to this treatment. Alternatively, small Pt nanocrystals (Pt NCs) have demonstrated arrested growth and apoptosis in cancer cells as a consequence of DNA platination and enhanced strand-breaks initiated by leaching Pt(II) ions from the NC surface in the acidic intracellular environment. Small Pt nanocrystals whose size is less than 3 nm demonstrate a higher reduction in cell viability than those with larger size, presumably owing to a relatively greater exposed surface area for dissolution. This observation, coupled with the identification of downregulation of multiple genes critical for cancer cell proliferation after treatment with Pt NCs, has led to an observed reduction in addressing drug resistance. Such nanocrystals tend to aggregate extensively in an aqueous environment, however, and we have developed well-defined Silicon nanotubes (pSiNTs) as a scaffold for effective nanocarrier for drug delivery of such PtNCs, taking advantage of nanotube high surface area, biocompatibility, and biodegradability. Functionalization with 3-(aminopropyl)triethoxysilane (APTES), followed by incubation with dilute K2PtCl4 solution results in the formation of PtNCs-pSiNTs well dispersed on the pSiNTs to avoid aggregation and release the platinum as the pSiNTs are resorbed over time, which results in significant cancer cell cytotoxicity-ty. To enhance the specificity of this material we conjugate Folic Acid (FA) to the Pt surface using as a Glutathione (GSH) linker, with the goal of enhanced targeting of overexpressed FARs and more selective cancer cell uptake.