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.