Texas A&M University – Corpus Christi
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A Model Train Maker
No full textA man standing next to four Model Trains he created displayed on a shelf in front of a fenc
A Lady and her Dogs
No full textA Lady stands besides a car with her Dogs sitting inside of it with debris in and around the ca
Development and verification of a computational model for the prediction of critical micelle concentrations (CMCs) for monoanionic amino acid-based surfactants
No full textA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in ChemistryIn this research, the critical micelle concentrations (CMCs) of nine novel monoanionic amino acid-based surfactants (AABSs) were experimentally determined and used to validate a CMC prediction model based upon molecular dynamics (MD) simulations. The AABSs were synthesized, purified, and had their CMCs determined via the electrical conductivity method. After parametrizing the AABSs with a hybrid gaff2/ff14SB force field, MD simulations were performed in which they were solvated with various explicit and implicit solvents at concentrations ranging from 0.1 – 100 mM. This produced several parameters which are believed to be representative of the thermodynamics of AABS solutions. A battery of polynomial regression and statistical uncertainty analyses were performed on the concentration-dependent values of each parameter for the AABSs. It was found that using the implicit solvent model IGB8 results in distinct measurement uncertainties before and after specific concentrations that strongly agreed with the experimental CMCs. Utilizing an algorithm based upon the t-test in which these values were identified, the total potential and van der Waal energies were found to be the best predictors of AABS CMCs. This was supplemented by a quantitative structure-property relationship (QSPR) study in which ionization potentials and van der Waal energies were identified as strong predictors for experimental CMCs. It was jointly concluded from the results of MD simulation analysis and QSPR regressions that electrostatic energies restrict the CMCs of this family of AABSs to a particular order of magnitude, while the van der Waal energies distinguish each AABs from one another. This research represents the first documented (and successful) attempt to theoretically predict CMCs for AABSs, as well as a pioneering unification between MD simulation- and QSPR-based theoretical studies.Environmental ScienceCollege of Scienc
Characterization of green surfactants with Dicarboxylate Polar Head
No full textA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in ChemistryThere has been a growing emphasis on developing biodegradable and environmentally friendly surfactants. One such relatively new class of surfactants that fall into this category are amino acid-based surfactants. This research focused on studying the physical properties (critical micelle concentration [CMC] and hydrodynamic radius) of aspartic and glutamic amino acid-based surfactants with two different types of hydrophobic tails (saturated hydrophobic chain with 13 carbons and an unsaturated hydrophobic tail containing 11 carbons). In addition to the varying types of hydrophobic tails and polar headgroups, this study also examined what effect different types of diamine counterions had on the physical properties examined. It is interesting to note that the type of diamine counterion or the amino acid head group, for the most part, had little effect on the physical properties examined. The major factor affecting significant changes in the physical properties was the type of hydrophobic tail. The CMC value obtained for saturated 13 carbon surfactants was significantly lower compared to the surfactant with an unsaturated hydrophobic tail containing 11 carbon chains. The range for the CMC values of saturated 13 carbon surfactant was 6 to 12 mM, while the range of the CMC values of unsaturated 11 carbon surfactant was found to have a value of 33 to 52 mM. The surfactant with the unsaturated 11 carbon chain had a significantly smaller hydrodynamic radius in comparison to the saturated 13 carbon surfactant. The range of the hydrodynamic radius for the unsaturated 11 carbon surfactant had a hydrodynamic range from 1 to 5 nm and the saturated 13 carbon surfactant was between 5 to 8 nm. However, there was one exception to this trend and that was the saturated 13 carbon glutamic surfactant in the presence of 1,2 diaminoethane counterion. It had a significantly larger size than all other surfactants measured. The hydrodynamic radius that was measured from saturated 13 carbon surfactant in the presence of 1,2 diaminoethane had a value of 106.47 nmEnvironmental ScienceCollege of Scienc
Binary solvent extraction of microplastics from complex environmental matrix
Get PDFSeparating microplastics from particulate organic matter (POM) is challenging, particularly for polyethylene and polypropylene, which are buoyant like POM. It is often done using a time-consuming procedure, often with hazardous waste generation. We developed a method using a binary solvent mixture (ethanol water) followed by water solvation to separate microplastics from estuarine POM and water. The isolated microplastics were quantified and characterized using μFT-IR and SEM, with particle sizes ranging from 30-2500 μm and percentage mass from 2.62-21.3% w/w in POM and 0.04-0.42%w/v for surface water respectively. Different polymer types, colors, and shapes were observed. Method recovery assessed using spiking yielded 89-93.1% and the method was validated by visual sorting with dye staining. This simple method aligns with Green Chemistry approaches by using ethanol, making it accessible to researchers throughout regions of the world where plastic debris is a major challenge but resources to study the problem are limited.This work was supported by the Matagorda Bay Mitigation Trust and Texas A&M University Coastal Health and Water Quality Laboratory. The authors acknowledge the support given to NL by the National Oceanic and Atmospheric Administration (NOAA), Center for Coastal and Marine Ecosystems, Office of Education Educational Partnership Program award (NA16SEC4810009). Also, the support given to JM by the TAMUCC Division of Research and Innovation, University Research Enhancement Award is hereby acknowledged
Topic 8: Interfaces
No full textObjectives for this topic:
Understand the concept of interfaces,
Recognize the requirements of interfaces,
Evaluate the differences between other polymorphic concepts and interfaces,
Program using Java’s interface synta
A fine-tuned large language model for improved click-bait title detection
No full textDepartment of Computing Sciences, College of EngineeringThe internet has experienced a widespread phenomenon of clickbait, especially on social media platforms and news websites. Clickbait headlines and descriptions attract clicks and generate ad revenue by using exaggerated, sensational, or misleading language. Clickbait can harm online users by wasting their time, spreading misinformation, damaging reputations, or even exposing them to malware or phishing attacks. Detecting clickbait manually is subjective and time-consuming since different people may have different opinions on what constitutes clickbait. Rule-based approaches, machine learning models[8], deep learning models[9] and natural language processing techniques are some of the existing methods for clickbait detection. However, clickbait detection remains a challenging task due to the diversity and complexity of clickbait content, as well as the constantly evolving strategies used by clickbait creators. In this research, we employed a methodology to detect clickbait titles using a fine-tuned large language model (LLM) that was trained on a limited dataset of clickbait titles
Dissolved inorganic nitrogen concentrations and isotopic values of wastewater treatment plants in a semi-arid region
No full textA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Coastal and Marine System ScienceWastewater treatment regulations evolve as detrimental ecological impacts of wastewater nitrogen loading becomes more apparent. Determining the significance of the N loading contribution of wastewater treatment plants to coastal waters in comparison to other primary N sources is necessary when creating efficient mitigation strategies. However, current research tends to be biased toward nitrate within effluent because it is often the main species of nitrogen entering the environment via the effluent. This work contributes concentration and isotopic data for all dissolved inorganic nitrogen (DIN) in both influent and effluent wastewater from three south Texas wastewater treatment plants equipped with activated sludge secondary treatment. The average (n=30) influent concentration of NH4+ was 2300±1100 µM, NO3- was 40.±35 µM, NO2- was 2.3±7.0 µM, and dissolved organic nitrogen (DON) was 140±41 µM. The average (n=33) effluent concentration of NH4+ was 190±270 µM, NO3- was 520±430 µM, NO2- was 14±8.0 µM, and dissolved organic nitrogen (DON) was 300±290 µM. Average isotopic ratios of influent ?15N-NH4+ (n=28) was 3.9±2.8‰, ?15N-NO3- (n=12) was 15±3.5‰, and ?18O-NO3- (n=12) 19±2.6‰. Average isotopic ratios of effluent ?15N-NH4+ (n=7) was 110±190‰, ?15N-NO3- (n=18) was 16±4.9‰, and ?18O-NO3- (n=18) 7.8±2.7‰. These wastewater isotope signatures local to the study’s semi-arid region were employed in Stable Isotope Analysis in R (SIAR) mixing model and compared to the use of literature signatures to convey the large variability in source apportionment that can be reported if locally characterized endmembers are not used in isotope source contribution models. The regional wastewater isotope signatures provided will help constrain isotope mixing models specific to the semi-arid Gulf Coast which in turn will help create informed nitrogen loading mitigation strategies. The treatment plants did not remove all the DIN in the influent and ~20% was subsequently returned to the environment. It was observed that activated sludge secondary treatment is capable of fully nitrifying raw sewage but is limited with respect to complete denitrification. Understanding the capabilities of activated sludge will help determine which tertiary treatment would be needed to remove excess anthropogenic nitrogen from wastewater. For the treatment plants in this study, simply increasing residence time may increase denitrification efficiency. The efficacy of this and other advanced treatment options should be explored further. Also, an argument for using enclosed aeration tanks to further reduce the release of anthropogenic nitrogen into the environment is given.Coastal and Marine System Science ProgramCollege of Scienc
Multiscale model reduction with local online correction for polymer flooding process in heterogeneous porous media
No full textIn this work, we consider a polymer flooding process in heterogeneous media. A system of equations for pressure, water saturation, and polymer concentration describes a mathematical model. For the construction of the fine grid approximation, we use a finite volume method with an explicit time approximation for the transports and implicit time approximation for the flow processes. We employ a loose coupling approach where we first perform an implicit pressure solve using a coarser time step. Subsequently, we execute the transport solution with a minor time step, taking into consideration the constraints imposed by the stability of the explicit approximation. We propose a coupled and splitted multiscale method with an online local correction step to construct a coarse grid approximation of the flow equation. We construct multiscale basis functions on the offline stage for a given heterogeneous field; then, we use it to define the projection/prolongation matrix and construct a coarse grid approximation. For an accurate approximation of the nonlinear pressure equation, we propose an online step with calculations of the local corrections based on the current residual. The splitted multiscale approach is presented to decoupled equations into two parts related to the first basis and all other basis functions. The presented technique provides an accurate solution for the nonlinear velocity field, leading to accurate, explicit calculations of the saturation and concentration equations. Numerical results are presented for two-dimensional model problems with different polymer injection regimes for two heterogeneity fields.D. Spiridonov work is supported by the grant of Russian Science Foundation No. 23-71-30013 (https://rscf.ru/en/project/23-71-30013/ (accessed on 1 June 2023))