TAMU-CC Repository
The Texas A&M University‐Corpus Christi (TAMU‐CC) repository is an open online site for storing and sharing digital content created or owned by the TAMU‐CC community. Content includes published and unpublished research and scholarship as well as archival materials. The service is managed by the Mary and Jeff Bell Library in cooperation with the Texas Digital Library. Learn more
Communities in DSpace
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- Research Institutions and Centers on TAMU-CC campus
- Items from Special Collections and Archives manuscript and photographic collections as well as the official university records.
- Find theses, dissertations, and other projects completed by students of Texas A&M University-Corpus Christi
Recent Submissions
Retention and strategic enrollment management at a community college in Texas
(2024-04-15) Benavides-Dominguez, Patricia; Benedetti, Christopher; Cervantes, Bernadine; Rodriguez, Tracie; Omoruyi, Felix
Student enrollment at community colleges within the U.S. has remained flat or decreased for over a decade (AACC, 2019). Before COVID-19, community colleges had been experiencing a steady decline in enrollment for approximately ten years (Irwin et al., 2021). The purpose was to determine whether demographic, environmental, and academic variables depend on a student’s decision to stay enrolled at Texas Community College (TCC) [pseudonym] for cohort years 2018-2019 and 2020-2021. The study used a quantitative, non-experimental, retrospective design (Cronk, 2020) to examine a subset of archival student data from TCC, a large public college in Texas. The subset of archival data consisted of 1,242 student records from the fall 2018 academic year (before COVID-19) and 791 student records from the fall 2020 academic year (after COVID-19). The researcher used Jamovi statistical software to conduct a chi-square test of independence to examine relationships between (a) demographic, environmental, and academic variables and (b) a student’s decision to enroll. For 2018 and 2020, descriptive statistics were generated for each variable to obtain frequency distributions of the levels within each variable. The levels with the highest number of counts for each variable included the following: RQ1: age (18-23), enrollment status (part-time), educational goal (associate degree), ethnicity (Hispanic), gender (female); RQ2: financial aid (yes); and RQ3: GPA (0.00-1.00). Additional proportion analyses indicated that the proportions of all levels within each variable were unequal (p<.01). The chi-square test of independence was conducted to determine whether a statistically significant relationship existed between each of the seven variables and students’ decision to enroll in the subsequent semester. For 2018 and 2020, the variables of age (18-23), enrollment status (part-time), financial aid (receipt of financial aid- yes/no), and academic outcome (GPA) played a critical role in student retention. Statistically significant relationships were absent between students’ decision to enroll and the following variables: educational goal, ethnicity, and gender.
Understanding hope as experienced by first-generation college students at Hispanic-serving institutions
(2024-04-16) Ayala, Claudia Amy; Hemmer, Lynn; Banda, Rosa M; Wilson, Kristina; Rodriguez, Stephanie
Utilizing interpretive phenomenological analysis (IPA), this study describes how the phenomenon of hope is experienced by six first-generation college students at South Texas Hispanic-Serving Institutions (HSIs), how student affairs contributed to that hope, and how these students understood the spaces on a college campus relative to their experiences of hope. The culturally engaging campus environment (CECE) model was used as a theoretical framework which allowed for consideration of how the HSI environment engages with students. The study’s findings add to the literature by revealing how hope surfaced from 1) within the individual participants, as it might if were a value, a character trait, or someone’s nature, and 2) within their relationships, with family, friends, colleagues, mentors, staff, and faculty. Furthermore, these hope experiences and interactions took place on HSI campuses and within the purview of student affairs. The implications for HSIs are that they can cultivate cultures of hope, by integrating culturally engaging campus environment tenets, which is valuable to first-generation college students.
Synthesis and characterization of aspartic acid-based tripeptide surfactants
(2024-05-03) Swonke, Roslyn Camille; Billiot, Eugene J.; Billiot, Fereshteh H.; Azad, Chandra; Olson, Mark A
Amino acid-based surfactants (AABSs) provide a more environmentally friendly option than traditional surfactants. The introduction of amino acids into the polar headgroup increases bioavailability and biodegradation. This study aimed to introduce three amino acids at the polar headgroup to form a tripeptide surfactant. However, this study used aspartic acid (Asp) as a central amino acid at the polar headgroup and utilized its dicarboxyl groups to form peptide bonds with auxiliary amino acids, thus forming bifurcated tripeptide surfactants. This study used stoichiometric coupling with diisopropylcarbodiimide (DIC) and n-hydroxysuccinimide (NHS) to aid in synthesis. Products were examined with proton NMR (1H-NMR) to analyze synthesis results. Then, solubility tests were performed to determine relative solubility and preliminary critical micelle concentration (CMC) studies were conducted. The 1H-NMR results revealed that the current method of bifurcated tripeptide surfactant synthesis should be amended to obtain desired products, as a mixture of bifurcated tripeptide surfactants and linear dipeptide surfactants formed. Solubility tests revealed the products formed organogels, while preliminary CMC tests revealed an estimated CMC of 51.20 mM.
NOx source apportionment and oxidation in a coastal urban airshed using stable isotope techniques
(2024-04-24) Shealy, Kaiya; Felix, J. David; Coffin, Richard; Abdulla, Hussain
NOx (NO + NO2) emissions decrease urban air quality, and its subsequent deposition can be a significant source of excess nitrogen loading to coastal waters. Photochemical reactions between volatile organic compounds and NOx in the atmosphere create ozone (O3). Previous studies suggest coastal urban airsheds tend to have a NOx limited ozone regime, so an increase in NOx would lead to an increase in O3. The first step to NOx emission mitigation and thus ozone reductions in these regions is to quantify the contributions of NOx sources. These sources have unique nitrogen isotopic compositions (δ15N-NOx) or “source signatures”, which allow the use of isotope mixing models to aid in determining emission source contribution. The corresponding oxygen isotopic composition (δ18O-NO2) of NO2 can be used to estimate the NO oxidation chemistry after emission from the sources. To investigate NOx dynamics in a representative coastal urban air shed, NOx and NO2 were passively sampled at four NOx and ozone monitoring stations of the City of Corpus Christi, Texas each month for one year and the nitrogen and oxygen isotopic composition (δ15N, δ18O) of each sample was measured. The δ15N-NOx and δ18O-NO2 values were applied to a Bayesian type mixing model to determine the apportionment of point (natural gas combustion) and nonpoint (biogenic soils, vehicles, marine shipping, biomass burning, and lightning) NOx sources in the air shed and determine NO oxidation chemistry (i.e. peroxy radical vs ozone pathway). Often, studies using this Bayesian mixing model include biomass burning and lightning as sources however, these are not continuous sources, and biomass burning and lightning events do not always produce enough NOx to be considered significant. We present an alternative to this “blanket” source approach by coupling HYSPLIT airmass back trajectories with lightning and fire remote sensing products to determine the significance of intermittent sources before including in a mixing model. This study also uses a more detailed approach to estimating the source signature of vehicular and industrial emissions. The average source signature for the combined diesel and gasoline vehicle fleet emissions was weighted according to proportion of diesel and gasoline emissions reported for the study region, and the industrial emission signature was expanded to also include marine shipping NOx emissions (weighted according to ship-type). This study determined NOx emissions are dominated by biomass burning emissions (41%) followed by vehicular (34%), lightning (12%), industrial (7%), and biogenic (6%) emissions and time periods of significant NOx emissions from biomass burning coincide with the burning season in Mexico. Emission apportionment results are within agreement of previous studies, but it is important to note the overlap in source signatures incorporated into the Bayesian mixing model. The most common isotopic endmembers for vehicular, biomass burning, and lightning overlap, and therefore introduce increased error into apportionment models. This highlights the future importance of having isotopic source signatures that are representative of specific regions of study. It was determined that the peroxy radical pathway (65%) is the dominant pathway for NO oxidation, with an increase in oxidation via the ozone pathway correlating with ambient ozone concentration. This study provided a first attempt at calculating the kinetic isotope effect (KIE) and subsequent enrichment factor of the radical pathway, estimated to be approximately -15‰. Results provide a greater understanding of NOx and ozone dynamics in coastal urban airsheds and can directly aid in the modification of coastal communities’ ozone action plans. Results enhance the understanding of atmospheric oxidative chemistry, information that is vital to constrain chemical transport models. Accurate source apportionments will be extremely useful for creating air quality regulations and ozone mitigation.
In Situ and remote sensing of aerosol properties and their influences in tropical oceanic warm rain systems
(2024-04-20) Santa Ana, Hailey; Liu, Chuntao; Xie, Feiqin; Shinoda, Toshiaki
This study includes two parts. First, in-situ aerosol particulates with size below 2.5 microns (PM25) observations are collected from the Nueces headwaters to the Texas coast, ending in Nueces Bay in April 2023. The potential links between parameters involved in the atmospheric and aerosol samples are examined. The second part focuses on examining the relationships between the properties of oceanic warm rain systems and aerosols by using remotely sensed observations. By utilizing the Navy Aerosol Analysis and Prediction System (NAAPS) AOD reanalysis product, collocated with Global Precipitation Measurement (GPM) data from 2014-2022, we examine the relationships between the aerosol types and concentrations and properties of warm rain systems over the Eastern Pacific and the Central Atlantic. The warm rain systems are selected by maximum echo top heights less than 5 km and size smaller than ~250 km2. Over the Central Atlantic, dust particles are the most abundant aerosol and peak in JJA with the emergence of the Saharan Air Layer. Over the Eastern Pacific, smoke and sulfate tend to be the most abundant particles with both peaking in MAM. We also examined the relationships between AOD and the properties of warm rain under different large-scale descent and near surface air temperature environments collocated from ERA5 reanalysis product. This study suggests the type of aerosol as well as large scale thermodynamic environmental parameters are important when understanding the relationship between aerosols and warm precipitation. However, the overall influence of aerosols in these systems does not seem to be significant based on the statistically analysis.