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Palladium-Tin Cations Enable the Formation of Palladium-Aryl Species
Get PDFA silylpalladium cationic complex was recently developed by the Gagne Lab. The complex could cleave C(sp3)-O bonds however it was not stable to air. In this work, a [(XantPhos)Pd-SnBu3][BArF24] complex was synthesized and characterized. This Pd-Sn complex was found to be stable to air. The complex was unable to complete the C(sp3/sp2)-O bond cleavage, yet it was found that it reacts with conjugated and isolated dienes to form Pd-allyl species. Additionally, the addition of electron-deficient aryl halides to the Pd-Sn complex resulted in ligand substitution to form Pd-Aryl bonds. The reactant and product in these reactions have a Pd(II) oxidation state, indicating two possible mechanisms for this reactivity. One pathway is an oxidative addition/reductive elimination, with the other being sigma-bond metathesis. Crystal structures were acquired for some of these Pd-Aryl products. The silylpalladium cationic complex was also reacted with aryl halides to compare its reactivity with the Pd-Sn complex.Bachelor of Scienc
Exploring Sentiment Analysis for Spanglish: Why Sociolinguistic Context Still Matters for NLP
Get PDFThis thesis explores the role of sociolinguistic context in natural language processing (NLP), with a specific focus on sentiment analysis of Spanish-English code-switched language. Despite recent advancements in large language models (LLMs), mixed-code text remains a challenge for NLP systems, often yielding significantly lower performance compared to monolingual tasks. To investigate this gap, I evaluate the performance of both small and large multilingual language models on benchmark sentiment analysis tasks using three mixed-code datasets: LinCE, the Bangor Miami corpus, and EN-ES-CS (Aguilar et al., 2020; Deuchar, 2010; Vilares et al., 2016). I further examine whether structural measures of code-switching (CS) can serve as reliable predictors of sentiment. Finally, I conduct a time-series analysis to explore whether emotional content tends to lead or lag behind code-switch events. My results show that while the utterance-level switching metric (Gambäck & Das, 2016) is statistically associated with sentiment class, it has limited predictive value in practice, and augmenting models with this feature does not yield meaningful performance gains. Similarly, my results suggest a statistically significant leading relationship between emotionality and CS time series, though the effect size is small. These findings suggest that syntactic or frequency-based features alone are insufficient for modeling sentiment in mixed-code contexts, and that future NLP systems may benefit from integrating deeper sociolinguistic insights.Bachelor of Scienc
Development of a quasi-three-dimensional portable mobile chest tomosynthesis system using carbon nanotube technology for enhanced diagnostic imaging
Get PDFTraditional mobile chest radiography is limited by the challenges oftwo-dimensional imaging, which can obscure anatomical details. This projectadvances an integrated X-ray system utilizing a carbon nanotube source toenable tomosynthesis, a limited-angle tomography technique that providesquasi-three-dimensional imaging for improved bedside visualization. As part ofthe development process, a custom collimator was modeled and an intuitivegraphical user interface was created—both serving as key proofs of concept forfuture clinical implementation. The system incorporates the CNT source arrayand supporting electronics into a commercially available mobile cart. Whileadditional refinement is needed for clinical readiness, preliminary testing demonstrates the system's viability.Bachelor of Scienc
Tri-Energy CBCT: Advancing Three-Material Decomposition with One-Step Inversion
Get PDFDual-energy cone-beam computed tomography has grown in popularity as an imaging modality due to its increased image quality compared to the standard single-energy. However, dual-energy imaging has not been successful in decomposing three materials. This report presents the potential of tri-energy cone-beam computed tomography for three-material decomposition using a one-step inversion algorithm for image reconstruction and material decomposition. The majority of the work done for this study consisted of developing the one-step inversion algorithm, as well as determining the correct filters to produce the low, middle, and high mean energy x-ray spectra needed for tri-energy imaging. Both the simulated and real scans employed the same phantom setup: water containing calcium and iodine inserts. The results indicate that one-step inversion has the potential to perform a higher quality three-material decomposition with tri-energy cone-beam computed tomography than what is currently offered by dual-energy. Prospects for future research are discussed in the conclusion.Bachelor of Scienc
Characterizing new mutations of ARF6 and ARF8 in Arabidopsis thaliana
Get PDFAuxin is a key phytohormone that regulates various developmental and maturation processes in plants. Intracellular auxin induces ARF (Auxin Response Factor) activation through the turnover of Aux/IAA (Auxin/Indole-3-Acetic Acid) repressors that otherwise interact with the C-terminal PB1 domain of ARFs. ARF6 and ARF8 are activating transcription factors that promote flower maturation. Previous studies used random mutagenesis and T-DNA insertions to knock out ARF6 and ARF8. However, the T-DNA alleles often lead to transgene silencing. We investigated the phenotypic effects of new CRISPR-Cas9-generated indel mutations in ARF6 and ARF8 on flower phenotypes and fruit development. Using targeted guide RNAs, students in an undergraduate CURE course generated knock-out (N-terminal domain) and putative “gain-of-function” (C-terminal, PB1 domain) mutations within null backgrounds for the other gene (arf6-crispr arf8-8 and arf6-2 arf8-crispr). We genetically characterized these mutations and performed flower organ length, seedling growth, fruit growth after emasculation, and low light stress assays of the mutants. Double mutants (arf6 arf8) with knockout (N-terminal ARF domain) mutations had arrested growth, closed buds, and indehiscent anthers. Double mutants including an arf6 PB1 domain mutation (C-terminal ARF domain) had weaker phenotypes. While we had hoped to identify a “gain” in ARF function to unmask Aux/IAA repressor effects, these mutants resemble partial loss-of-function mutants in light stress, hypocotyl growth, and emasculation assays conducted thus far. Through this investigation, we can uncover effects of Aux/IAA proteins on ARF function and may develop tools to manipulate reproductive fitness in flowers and fruits and providing applications in managing crop yield.Bachelor of Scienc
Effect of Simulated Space Stressors on the Mitochondrial Function in White Adipose Tissue and Potential Therapies
Get PDFAs exploratory missions continue to venture into the cosmos, it is crucial to understand the health hazards associated with deep space travel and to develop therapeutics to mitigate the harmful pathologies that may arise. The dangers of space travel include, but are not limited to, microgravity, solar particle radiation, gamma radiation, and heavy ion radiation (e.g., 56Fe). Space travel has been linked to age-related diseases such as muscular atrophy, decreased bone density, cognitive changes, inflammation, and oxidative stress in adipose tissue (AT). In this study, we focused on AT because astronauts have exhibited hyperlipidemia and an increased incidence of reactive oxygen species (ROS) during space travel, factors that affect AT metabolism and mitochondria biosynthesis. Specifically, we are interested in addressing the increased catabolism of AT in astronauts and preventing the overgeneration of beige/brite adipose tissue (BeAT), which metabolizes substrates to generate heat through thermogenesis rather than producing chemical energy. We used mouse models housed at the Brookhaven National Laboratory (BNL) to simulate space stressors such as radiation and microgravity. The study included six experimental groups: galactic cosmic radiation (GCR), solar particle events (SPE), and Sham (control). Each group was divided into two subgroups: one receiving antagomir (ag) treatments targeting specific microRNAs (miRNAs) and one without treatment. Additionally, these six groups were subdivided into 12 subgroups based on loading conditions: half underwent hindlimb unloading (HU) to simulate microgravity, while the other half remained under normal loading (NL). The antagomirs targeted three primary miRNAs: miR-125-5p, miR-16-5p, and miR-let7a-5p- which are implicated in vascular health but have diverse functions depending on the tissue they are expressed in. To evaluate the effects of antagomir treatment, we measured mitochondrial DNA copy number (mtDNA-CN), a biomarker of mitochondrial function associated with overall mortality in various disease conditions. We hypothesized that exposure to space stressors would decrease mtDNA-CN in white adipose tissue (WAT), correlating with reduced mitochondrial biosynthesis and thermogenesis. Furthermore, we posited that antagomir treatments would mitigate these pathological effects by restoring mtDNA-CN ratios to a normal level. Our findings revealed that radiation exposure did not significantly influence mtDNA-CN levels, nor did loading conditions. However, there was a slight trend toward higher mtDNA-CN in the simulated microgravity groups, though this was not statistically significant. Interestingly, we observed a pronounced effect of antagomir treatment: regardless of radiation exposure or loading condition, antagomir-treated groups exhibited a sharp decrease in mtDNA-CN.Bachelor of Scienc
Adding Colors to the Chameleon: The Words of Kings and the ‘Infinite Variety’ of Political Rhetoric in Shakespeare’s History Plays
Get PDFThe art of rhetoric has long been defined by its seemingly paradoxical nature and ever-changing social functions. Ranging from political to philosophical to the emerging need for different persuasive techniques, rhetoric has found itself manifested in ever-changing mediums, forms, and functions. Despite its adaptability, scholars have often noted a persistent mistrust of rhetoric—whether viewed as a tool of law and political power, mere verbal ornamentation, or a stylistic linguistic device. Yet it is precisely this tension between suspicion and necessity that underscores its enduring presence, particularly in contexts where authority must be performed and legitimized. This thesis examines how that tension manifests, adapts, and morphs within Shakespeare’s English history plays, where rhetoric emerges not as mere embellishment but as a central mechanism of governance, persuasion, and self-fashioning. Tracing the evolution of rhetorical practice from classical antiquity to Renaissance England, this project explores Shakespeare’s sustained engagement with the power of language—its capacity to shape authority, manipulate perception, and define the legitimacy of rule. By analyzing the rhetoric of his kings, this project investigates how Shakespeare interrogates the relationship between language and leadership, revealing rhetoric as essential to both the performance and consolidation of power.Bachelor of Art
Thermal and Hydric Conditions Shape Amphibian Microhabitat Use
Get PDFIncreasing extreme weather events such as heatwaves are predicted to inflate vapor pressure deficit (VPD) levels. Animals that cannot adaptively keep up with these events are at risk of dehydration. Previous studies have ignored or confounded the effects of temperature and relative humidity on hydro-regulatory behavior. This study disentangles these factors by using a 2x2 factorial design to test the relative influence of temperature (25°C and 30°C) versus VPD (0.7 kPa and 1.4 kPa) on American Toad (Anaxyrus americanus) and Cane Toad (Rhinella marina) behavior and physiology. Every day for 10 days for each of the four treatment periods, the position of each individual was recorded four times: 9:00, 13:00, 17:00, 21:00 (nighttime observation). A. americanus used the five microhabitat types variably (Dish, Open, Buried, Wet hide, Dry hide), while R. marina largely used Wet hides across all treatments. A. americanus was noted to manipulate the environment to create new microhabitats using wet substrate for burying. Both temperature and humidity significantly influenced wet microhabitat use for A. americanus. R. marina also showed a significant increase in wet microhabitat use under dry conditions, but there was no effect of temperature alone; instead, there was an interactive effect between temperature and humidity. Temperature and humidity significantly influenced the use of the Open microhabitat with warmer temperatures and drier conditions associated with decreased Open microhabitat use. Ultimately, both species adjusted their microhabitat use in response to intensified VPD and temperature levels, indicating that behavioral hydroregulation is flexible and species-specific. Ectotherms are not passive victims of climate change and can display significant behavioral plasticity in response to desiccation risk. Conservation efforts should prioritize the upkeep and availability of appropriate microclimate refugia, including moist substrates, or water-providing shelters to buffer at-risk species from heightened VPD and thermal extremes. Bachelor of Scienc
Accessing Isotactic Polyvinyl Esters Through the Post-Polymerization Modification of Isotactic Polyvinyl Ethers
Get PDFTuning the stereochemistry of chiral centers formed during vinyl polymerization enables access to the enhanced mechanical strength, crystallinity, and thermal stability often found in isotactic polymers. This work explores the impact of stereocontrol on the material properties of polar vinyl polymers, namely polyvinyl esters, which has remained unexplored thus far. Although methods for controlling tacticity in nonpolar vinyl monomers are well-known, analogous strategies for polar monomers such as vinyl esters remain underdeveloped due to challenging reactivity profiles. Herein, we investigate a post-polymerization modification approach of accessing isotactic polyvinyl esters by oxidizing atactic and isotactic forms of poly(isobutyl vinyl ether) [PIBVE] to generate poly(vinyl isobutyrate) [PVIB], then reducing backbone ketone side products before re-acylation. Characterization including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), dynamic mechanical analysis (DMA), and NMR spectroscopy was employed to tabulate important structural, thermal, and mechanical properties for an array of polymers, and to optimize reaction setups. In parallel, molecular dynamics simulations were conducted to examine how backbone ketone side products affected glass transition temperatures and solubility parameters. Our results demonstrated that high tacticity in PVIB led to elevated glass transition temperatures, increased crystallinity, and improved performance relative to atactic analogs.Bachelor of Scienc
Prevalence of Kidney Stones in US Hispanic/Latino Adults: Findings from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).
Get PDFThe prevalence of kidney stones in US adult is approximately 9.3%. Kidney stone disease is costly to patients and the healthcare system. However, there are limited data regarding prevalence of kidney stones in U.S. Hispanic/Latino adults, which represent 19.5% of the US population. The objective of this study was to evaluate the prevalence of kidney stones using data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)