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Mechanistic characterization and application of ion/ion reactions between fluoranthene and metal-adducted biomolecules.
No full textCarbohydrates and peptides are two fundamental biomolecules that are involved in a variety of cellular functions that are important to understand due to their significance as biomarkers for numerous types of diseases. Carbohydrates specifically are very difficult to analyze due to the multitude of isomeric structures that exist within human biological systems. Therefore, there is still a significant need to identify and sequence carbohydrates and peptides to improve the scientific understanding of their biological functions. Ion/ion reactions between fluoranthene and multiply charged cationic biomolecules, which causes electron transfer dissociation (ETD), has been demonstrated to be one of the most promising methods for characterizing the structures and sequencing carbohydrates and peptides. For several carbohydrates and peptides, the formation of multiply charge cations from electrospray ESI can only be achieved through adduction of metals. ETD is a radical-based dissociation method, however the reaction products and mechanisms are not well understood for metal-adducted carbohydrates and peptides. Here we use deuterium labeling to improve our understanding of the reaction mechanisms of fluoranthene based ion/ion reactions and how the products are impacted by the biomolecule (carbohydrate or peptide) and the charge carrier (proton, group II metal, or transition metal). Chapters two and three discuss the mechanistic and fragment product discoveries and methodologies used to achieve them. Here, we discover evidence of extensive intermolecular proton transfer or gas-phase HDX occurring during ion/ion reactions between metal-adducted carbohydrate fragments and fluoranthene. For metal-adducted peptide fragments, we detected minimal gas-phase HDX from ion/ion reactions with fluoranthene for most fragments. From these mechanistic investigations of ion/ion reactions with fluoranthene, we also wanted to develop novel methods to differentiate isomeric carbohydrates. In chapter four, we investigate the development of ET based dissociation method that can differentiate linkage and branching human milk oligosaccharide isomers. In chapter four, we examined the ability to form diagnostic fragments by combining Co2+-adduction with ETD and electron transfer higher-energy collisional dissociation (EThcD). We found that only Co2+-adduction combined with EThcD could form diagnostic fragments for all HMO isomers. Here, we have developed a novel method for identifying and characterizing carbohydrate isomers based on our initial mechanistic discoveries
The mother and the imperiled child : a literary type scene in the composition of 1 and 2 Kings.
No full textSet among the narratives of royal figures in the book of Kings are captivating stories about marginalized characters such as mothers and children. On seven occasions in the book of Kings a mother(s) presents her imperiled son(s) to a man of God. I argue that the consistent cast of characters and sequence of events in all of these stories identifies them as a literary type scene. My dissertation examines how narratives about mothers and imperiled sons fit into the larger compositional structure of the book. My research builds on insights from childist scholars and recent research on the symbolic function of mothers/motherhood in Hebrew narrative. The fate of the children varies: some of the children die (1 Kgs 3:16-28; 14:1-18; 2 Kgs 6:26-31), others are revived (1 Kgs 17:8-24; 2 Kgs 4:8-37), and still others are spared from harm (2 Kgs 4:1-7; 11:1-21). Additionally, the socio-economic status of the characters involved varies widely. The mothers include anonymous poor and rich women, royal figures, and prostitutes. The men of God are kings, prophets, and priests. This dissertation argues that these stories were incorporated into the Book of Kings during the Josianic and Persian periods. During the Josianic period, the mother and imperiled son type scene symbolizes the downfall of Israel and the plight of Judah prior to the Babylonian exile. During the Persian era, stories about mothers and imperiled sons emphasize themes of restoration
Holistic student success : a qualitative single case study of upper-level undergraduate students’ perception of thriving at a private liberal arts institution.
No full textHistorically, student success has been measured primarily by grades, retention, and graduation rates (Astin, 1985; Bean & Eaton, 2000; Pascarella & Terenzini, 2005). However, researchers argue that these metrics fail to capture the full complexity of student thriving, encompassing academic, social, and psychological well-being (Schreiner, 2010a, 2013, 2020). Many students today are facing mental health challenges, financial stress, and disengagement, which contribute to stagnating graduation rates and declining persistence (Kinzie, 2020; Lipson & Eisenberg, 2018; Tinto, 2012). Although Lipscomb University’s graduation and retention rates slightly exceed national averages, the Healthy Minds Survey (2022) revealed that only 48% of Lipscomb students reported flourishing, along with rising demand for mental health and student support services (Lipscomb, 2023). This study applies Schreiner’s (2009, 2013) Thriving Student Framework to examine the experiences of thriving upper-level students at Lipscomb.
In this problem of practice used a qualitative approach to explore how undergraduate students at a private liberal arts institution perceive their thriving, specifically related to the five factors of thriving (Schreiner, 2013). Specifically, my study is a qualitative single case study with a human-centered design approach informed by a constructivist worldview. The research explored students’ academic, psychological, and interpersonal well-being and engagement. I collected data in three phases: questionnaires, photo-elicitation interviews, and semi-structured interviews. Understanding what thriving students perceive as contributing to their ability to thrive can inform institutional strategies to foster holistic student well-being and ensure more students move beyond merely surviving college to truly thriving. This study provides valuable insights into the experiences of thriving upper-level undergraduate students at Lipscomb University, emphasizing the importance of academic determination, faculty support, engaged learning, and social connectedness. Additionally, the study underscores the critical role of faculty mentorship in student thriving, highlighting the need for structured faculty development programs that promote student-centered engagement and dynamic instruction. Furthermore, this research opens pathways for future studies on diversity, belonging, and student engagement, providing university leadership with a foundation for fostering a more inclusive and supportive campus environment
The arduous climb to the top : a qualitative single case study exploring the self-determination of Black women finance leaders in career advancement.
No full textDespite equity-based programs within the finance industry, Black women remain underrepresented in senior leadership roles. The underrepresentation disparity creates a visual and legitimate power imbalance between Black women and their White male counterparts who dominate senior leadership representation. The representation imbalance for Black women leads to lower salaries, fewer promotional opportunities, and a lack of access to professional development resources. Further, the underrepresentation adversely affects corporate ethos, decision-making processes, and collaboration. The finance industry can gain greater utilization of the talents and abilities of Black women by addressing career advancement obstacles and cultivating a work environment that values cultural diversity and racial equity. I conducted a qualitative single case study to explore the self-determination of Black women finance leaders to advance their careers within the constructs of institutional racism shaped policies and practices. Using Deci and Ryan's (1980) self-determination theory as a theoretical framework, the study highlighted the lived experiences of four Black women finance leaders regarding relatedness, competence, and autonomy factors that influenced their career advancement decisions. The focus of the study included understanding factors that contributed to the self-determination of the participants and the subsequent impact on their career advancement decisions. I analyzed the three prevalent themes in data collected via a questionnaire and one semi-structured interview. The research methodology allowed me to capture participants' descriptives regarding their deployment of diverse forms of capital to advance using self-determination amidst workplace racial inequities professionally. The findings highlighted many implicit organizational obstacles and aids that positively or negatively impacted participant's self-determination. My analysis categorized the findings into themes that ultimately formed a set of recommendations. The first theme indicated that Black women finance leaders leveraged self-determination to promote career progression through network connections with political capital. The second theme indicated that Black women finance leaders leveraged self-determination and intrinsic motivation to increase their intellectual capital and reach professional goals. The final theme indicated that Black women finance leaders leveraged self-determination and community relationships to advance self-actualization and professional development. Addressing these organizational challenges requires a comprehensive senior executives-led strategy that includes culturally diverse solutions
A qualitative multiple case study : collegiate career readiness programs and Black graduates' career self-efficacy in corporate America.
No full textCareer readiness is essential to preparing undergraduate Black students for corporate America. Black employees comprise 12% of the entry-level professional positions in private industry but only seven percent of the managerial positions (Hancock & Williams, 2021). They are 30% more likely to depart their companies early (CTI, 2019) and experience higher attrition than their White counterparts at all levels (Hancock & Williams, 2021). They experience microaggressions (Holder et al., 2015) in racialized environments (Sisco, 2020). Collegiate career readiness programs fall short of providing the skills and experience to prepare Black graduates for the unique challenges in corporate America. Through the lens of self-efficacy theory (Bandura, 1997), I conducted an exploratory multiple-case study to explore the career self-efficacy of recent Black graduates working in corporate America by describing their experiences with collegiate career readiness programs and the corporate work environment. I purposefully selected six participants who attended a Predominately White University (PWI) and a Historically Black College and University (HBCU) in the Mid-Atlantic area. I bounded the two cases by the university sites, with three participants in each case. I collected data via a questionnaire with a career competency self-assessment and semi-structured interviews. The study's findings emerged from the Black graduates' experiences and perspectives related to their career readiness. The graduates had confidence in their abilities to perform their duties and valued undergraduate career development experiences. However, their university career readiness programs did not offer many unique career skills required to prepare the Black graduates for corporate environments. Their corporate workplaces lacked crucial support systems for Black employees, such as mentors of similar backgrounds and career guidance. This lack of support and the unique skills required to adjust to corporate cultures underscore the need for Higher Education Institutions (HEIs) to improve career readiness programs to address the needs of Black students and graduates for careers in corporate America
"Across a border where nobody could tell anymore in the fog who was Mexican, who was Anglo, who was anybody" : critical construction of Whiteness in postwar American fictions of Baldwin, DeLillo, Pynchon, and McCarthy.
No full textThis dissertation investigates the critical construction of whiteness in postwar American literature through the works of James Baldwin, Don DeLillo, Thomas Pynchon, and Cormac McCarthy. I argue that whiteness functions not as a neutral identity but as a pervasive narrative force that structures perception, organizes power, and authorizes meaning while often disavowing its own presence. Drawing on critical race theory and postmodern literary analysis, this project explores how Baldwin portrays whiteness as a cultural performance sustained by denial and fantasy; how DeLillo frames it as an aesthetic ideology tied to abstraction and erasure; how Pynchon reveals its entanglement with political control and systemic violence; and how McCarthy renders it as an apocalyptic inheritance embedded in ontological crisis. Through close readings, this study traces the shifting modalities of whiteness across these authors’ works and demonstrates how postwar fiction at once encodes, critiques, and destabilizes whiteness as a cultural logic
Late Pleistocene paleoclimate at Waco Mammoth National Monument, TX : evidence for cooler, drier regional climate conditions during three mammoth fossil assemblages.
No full textThe Waco Mammoth National Monument (WMNM) is a paleontological site in Waco, TX, that preserves the remains of approximately eighteen Columbian mammoths remains. Previous studies have proposed two different scenarios to explain the high density of mammoth remains at the site. The death and deposition of mammoth remains was caused by (1) a dramatic episode of incision and rapid burial or (2) the mammoth fossils represent an attritional assemblage that died due to a prolonged drought. This study assesses these scenarios by presenting data from detailed stratigraphy, grain size analyses, and multiple geochemical proxy datasets from inside the dig shelter. Overall, our results suggests that the mammoth assemblage was not deposited in a single, dramatic episode of incision. Instead, the results demonstrate that multiple layers of Late Pleistocene species at WMNM were deposited on a distal flood plain in a semi-arid to dry, sub-humid climate. These results also support the hypothesis that the WMNM is an attritional assemblage that accumulated in an interval of prolonged drought, which has important implications for understanding site formation, taphonomy of the fossil assemblage, and regional climate during the Late Pleistocene
Leveraging crystalline carbon nitrides as semiconducting scaffolds for light-driven catalysis in aqueous media.
No full textThis research aimed to interrogate the material properties of crystalline poly(triazine imide) for use as a scaffolding light absorber, leveraging of its unique composition for bandgap tunability, and integration of catalytic metal cations into the polymeric framework followed by exfoliation towards two-dimensional morphology. Previous research work in the Maggard group has produced the synthesis and characterization of a highly ordered version of carbon nitride, poly(triazine imide) lithium chloride or PTI-LiCl, developed through a flux-assisted high temperature synthesis in vacuum. In this research project, we show that with adsorption of molecular catalysts, Co(qpy)(Cl2)-Ph-COOH and Fe(qpy)(Cl2)-Ph-COOH, onto the semiconductor surface CO2 reduction to CO can be selectively driven under light irradiation in a primarily aqueous-based solution, which has not previously been shown. In both cases, the selectivity for CO evolution was over 95%, and when using Co(qpy)(Cl2)-Ph-COOH, rates over 2.0 mmol·g-1·h-1 could be achieved.
The experimental band gap of PTI-LiCl generated here, of ~3.1 to 3.2 eV, limits its absorption to predominantly ultraviolet wavelengths of light. A smaller bandgap energy, i.e. a wider solar absorption profile was investigated via molecular modifications to the PTI-LiCl polymeric framework. This was achieved by incorporating various molecular precursors into its synthesis and resulting structure. By this approach, the altered elemental composition of the C:N ratio within, gave rise to newly introduced states at the frontier energy levels. These experimental findings yielded improved photocatalytic activity for the hydrogen evolution reaction and total water splitting at visible-light wavelengths for the molecularly modified compounds, in comparison to the parent PTI-LiCl. Lastly, exfoliation efforts have also successfully shown that Cu-containing PTI, produced by a flux-assisted substitution of coordinated Li cations into another PTI structure, PTI-LiBr, is capable of being dissolved into few or mono-layer formations. This transformation increases the material’s available surface area while also retaining the catalytic metal sites within its interlayer cavities. These explorations illuminate the versatility that crystalline carbon nitride systems have to offer the world of solar energy conversion as a vehicle for electron/hole transfer and adjustable morphology dependent upon the synthetic material preparation
Truncated BGG complexes and syzygies of some thickenings of determinantal varieties for hermitian symmetric pairs.
No full textLet S be the graded ring of complex-valued polynomial functions on one of the following spaces: the space of p × q complex matrices, the space of symmetric n × n complex matrices, or the space of antisymmetric n × n complex matrices. The ring S carries a natural multiplicity-free action of GLp × GLq or GLn, respectively, with irreducible representations indexed by certain integer partitions.
We study the graded ideal Ia×b ⊂ S generated by the irreducible representation corresponding to a rectangular Young diagram of shape a × b. Our focus is on the minimal free resolution of these ideals, particularly their linear strand. While the case of general p × q matrices is well understood (due to work of Raicu and Weyman), much less is known in the symmetric and antisymmetric cases, except when b = 1.
We approach these cases uniformly using the framework of Hermitian symmetric pairs. Let GR be a simple real Lie group (with finite center) of Hermitian type, and let K be the complexification of a maximal compact subgroup. Let g = p− ⊕ k ⊕ p+ be the complexified Cartan decomposition, and let S be the ring of complex-valued polynomial functions on p+. The K-action on S is multiplicity-free, with irreducible summands again indexed by partitions. The three classical cases correspond to GR = SU (p, q), Sp(2n, R), and SO∗(2n), respectively.
Our main result is that, in each case, the first linear strand of the minimal free resolution of Ia×b is a (twisted) subcomplex of the BGG resolution of the irreducible highest weight (g, K)-module of highest weight λ = [−(a − 1)c + (b − 1)]ζ, where ζ is the fundamental weight of the noncompact simple root, and c depends only on GR. In special cases (e.g., when a = 1, a = n − 1, or a = (n − 1)/2), we explicitly compute the entire resolution, Betti tables, and Hilbert series
Coupling between helicase and polymerase activities ensures genomic integrity in E. coli.
No full textDNA replication is a tightly regulated process in all Domains of life, crucial for the passing down of genetic information to the next generation. To achieve this, the dynamic interactions between replisomal proteins are well orchestrated to replicate DNA accurately and with minimal error. Of these interactions, the coordination between the polymerase and helicase are of vital importance. To investigate this coupling of enzymatic activities, site specific mutations were introduced into the dnaX gene; that codes for τ-subunit of the clamp loader complex in Escherichia coli (E. coli). τ plays an important role in acting as the lynchpin that physically couples the DnaB helicase and the α-subunit of Polymerase III core. The mutations introduced were targeted to disrupt the α-τ interactions. As expected the dnaX:mut strains exhibited phenotypes of severe genomic and cellular stress. To further explore the mechanisms underlying this coupling phenomenon, the same mutations were utilized for in vitro enzymatic assays. In an ideal scenario, DNA synthesis and unwinding will proceed together at the same rate. However, replication forks may encounter roadblocks even under normal physiological conditions, which may lead to polymerase stalling. In this event, the helicase would slow allowing the polymerase to catch up, minimizing the amount of exposed single-stranded DNA (ssDNA). We postulate that τ is crucial in regulating the speed of unwinding by the helicase to maintain coupling with the polymerase. By inducing a conformation change in the DnaB helicase, τ can alter the speed of the helicase to maintain coupling with both enzymes. This work shows the importance of coupling the activities of two essential replisomal proteins and how this mechanism is used to preserve the genomic integrity of bacterial cells