Digital Commons Network^™

Labeling And Characterization Of Exosomes To Elucidate Their Cellular Uptake Within Tumor And Stromal Cells, Rabab Hamzah

Theses and Dissertations

Exosomes are natural nanoparticles released by all eukaryotic cells studied thus far and a wide range of different biological fluids. Their components are derived from parent cells and can be transferred to other cell types and locations in an organism which makes exosome a promising nanosized-agent to treat and diagnose various diseases. Several research studies have been done to load exosomes with drugs and nucleic acids to develop a number of new therapeutic nano-vehicle. A few research studies have been done to combine these natural nanoparticles (exosomes) and artificial nanoparticles to develop a new theranostic nano-agent. In this research, we …

Mechanical And Material Characterization Of Advanced Materials For Tissue Regeneration, Bailey Kylara Ricketts Jackson

Theses and Dissertations

In natural disasters and military deployment operations, injury to long bone can cause extensive damage and be difficult to treat and heal quickly. Explosive devices and trauma often produce long-bone (>2-cm length) wounds that are more complicated than common fractures. Due to the size and complexity of these injuries, they can be difficult to treat in a battlefield environment and take a long time to heal completely and properly. Even after the long healing period, these injuries often require rehabilitation to strengthen the muscles that have weakened in the wounded limb. For military applications especially, these effects can put …

Fabrication And Comparative Study Of Horizontal And Vertical Electrospun Protein-Polysaccharide Nanofiber Biomaterials, Ashley Rivera-Galleti

Theses and Dissertations

The use of biocompatible and biodegradable composite materials for biomedical applications has attracted the attention of many researchers in the past few years. In this study, we fabricated nanofibers of silk fibroin and cellulose and its derivatives to amalgamate their unique properties into a single material. The production of these nanofibers via electrospinning is of particular interest, and whereas several studies have been done on normal nanofibers, the formation of branched nanofibers is an exciting area not currently explored. Blend solutions are formed by dissolving silk and cellulose/cellulose acetate in formic acid separately and mixing to achieve the desired ratios. …

Perron Theorem For Delay Differential Equations, William Barker

Theses and Dissertations

This note discusses results furthering the study of bounded solutions of non-homogeneous second-order differential equations with delay. The equation of interest has already been shown to possess unique bounded solutions in accordance to Perron's Theorem. We will determine the negativity of the solutions given a positive forcing term by establishing a uniform bound regarding small time delay.

Forest Structure, Above-Ground Carbon Stocks, And Productivity Along An Elevational Gradient In The Ecuadorian Andes, Esteban Pinto

Theses and Dissertations

The Andean forest provides a natural laboratory for evaluating long-term interactions between forests and variation in environmental parameters along elevational gradients. In particular, the mechanisms that control above-ground carbon stocks (AGC) and natural dynamics in mountain ecosystems constitute a potentially powerful tool for understanding the function of these ecosystems and their response to current climate change scenarios or past human disturbances. The present study integrates biotic (rarefied species richness and leaf traits) and abiotic (climate, soil properties and degradation) factors as possible drivers of AGC stocks, AGC net change (AGCnt), AGC productivity (AGCp) and AGC mortality (AGCk), along an elevational …

Investigation Of The Role Of Hydrophobic Amino Acids On The Structure-Activity Relationship In Ponericin L1 From Neoponera Goeldii, Nicholas Patrick Schifano

Theses and Dissertations

Due to the increase prevalence of antimicrobial resistance (AMR) antibiotic alternatives have been of great interest. Antimicrobial peptides (AMPs) and polymers like polymethacrylates that mimic AMPs are two non-traditional antimicrobial agents that have been investigated thoroughly over the years as a potential solution to the AMR problem. This study will further the understanding of the L1 peptide by investigating the role hydrophobic amino acids have on the antimicrobial activity. Biophysical and microbiological techniques were utilized to show that the L1 hydrophobic derivative showed enhanced binding to anionic lipid bilayers while maintaining low hemolytic activity. This study also elucidates the effect …

Drugs That Protect Against Protein Aggregation In Neurodegenerative Diseases, Samuel Kakraba

Theses and Dissertations

Cytotoxic protein aggregation is characteristic of age-associated neurological disorders such as Alzheimer's disease (AD), Huntington’s disease (HD), and Parkinson’s disease (PD). This thesis focused on identification of small molecules that are effective at reducing cytotoxic protein aggregation as potential drugs for treatment of neurodegenerative diseases. SH-SY5Y-APPSw neuroblastoma cells were used as a model of amyloidopathy to identify lead candidates. The lead candidates were further characterized in Caenorhabditis elegans strains CL4176 (an AD model that accrues amyloid deposits and develops progressive paralysis with age), and AM141 (a model of HD-like aggregation, which displays fluorescent aggregates in muscle followed by progressive paralysis). …

Engineering A High-Throughput Screening Platform For Assessing Developmental Neurotoxicity Throughout Head- Regeneration In Schmidtea Mediterranea, Johnathan James Morris

Theses and Dissertations

The increase in commercially used chemicals that are inadequately evaluated for safety and risk to development has created a reticent threat to human health. Addressing these deficiencies is compounded by limited methodologies to determine the etiology of exposure-related developmental neurotoxicity (DNT). Current means of assessing DNT are largely retrospective and limited by the expensive, time-consuming, and labor-intensive use of laboratory animal models, thereby motivating a global research effort to produce alternative chemical screening assays. In this work, we have developed a novel high- throughput platform that serves as a new tool to evaluate the effects of exogenous chemical exposure on …

Acclimation Of Contact Impedance And Wrist-Based Pulsatile Signal Measurements Through Electrical Bioimpedance, Diego A. Leon

Theses and Dissertations

The purpose of this research is to expand the understanding of certain properties of electrodes used for electrical bioimpedance measurements. Specifically, this work investigates the acclimation effect of the skin-electrode interface contact impedance. It also attempts to study the relationship between electrode spacing and amplitude of bioimpedance pulsatile signals. It was found that as soon as dry electrodes are placed on the skin, the contact impedance exponentially decreases until it reaches a constant level. The acclimation time, time to reach a constant contact impedance, is dependent of the electrode size and frequency. Increasing the size of the electrode, as well …

Verification And Validation Of Radiation Protection Factors From Monte Carlo Simulations, William J. Erwin

Theses and Dissertations

This dissertation describes the verification and validation of methods for producing radiation protection factors (RPFs) using experiments and Monte Carlo N-Particle 6 (MCNP6) simulations. RPF validation of a steel enclosure using a plutonium-beryllium source produced a validated RPF with statistically significant agreement between neutron MCNP6 models and experiments and a gamma protection factor (GPF) with statistically significant agreement to the measured GPF. Efforts to validate more complex enclosures using the Fast Burst Reactor (FBR) yielded the first-ever direct measurements of this reactor’s prompt gamma emission spectrum and revealed irreconcilable differences between the FBR facility-provided source spectrum and spectrometer measurements, resulting …

Enterprise Resource Allocation For Intruder Detection And Interception, Adam B. Haywood

Theses and Dissertations

This research considers the problem of an intruder attempting to traverse a defender's territory in which the defender locates and employs disparate sets of resources to lower the probability of a successful intrusion. The research is conducted in the form of three related research components. The first component examines the problem in which the defender subdivides their territory into spatial stages and knows the plan of intrusion. Alternative resource-probability modeling techniques as well as variable bounding techniques are examined to improve the convergence of global solvers for this nonlinear, nonconvex optimization problem. The second component studies a similar problem but …

Medication Assisted Treatment: Examining Enrollment And Demographic Factors Of Treatment, Antwana Letoya Drayton

Theses and Dissertations

Opioid Use Disorder (OUD) has been a long-standing epidemic concern related to the continuous growth of variations of the substance and its’ potency. Due to the versatility of the substance to be both an illicit drug and also a prescription medication, the interest in controlling and monitoring its’ use creates a greater public health concern. Treatment overtime has been revitalized to directly address the social, biological, and physiological difficulties of patients with OUDs. Medication Assisted Treatment (MAT) has been explored and has become one of the most widely used plans for treatment of Substance Use Disorders (SUDs) related to pain …

Characterizing Convolutional Neural Network Early-Learning And Accelerating Non-Adaptive, First-Order Methods With Localized Lagrangian Restricted Memory Level Bundling, Benjamin O. Morris

Theses and Dissertations

This dissertation studies the underlying optimization problem encountered during the early-learning stages of convolutional neural networks and introduces a training algorithm competitive with existing state-of-the-art methods. First, a Design of Experiments method is introduced to systematically measure empirical second-order Lipschitz upper bound and region size estimates for local regions of convolutional neural network loss surfaces experienced during the early-learning stages. This method demonstrates that architecture choices can significantly impact the local loss surfaces traversed during training. Next, a Design of Experiments method is used to study the effects convolutional neural network architecture hyperparameters have on different optimization routines' abilities to …

Adaptability As A Moderator On The Impact Of Childhood Sexual Abuse And The Development Of Posttraumatic Stress Symptoms, Courtney Marie Kalmanson

Theses and Dissertations

Globally, it is estimated that 11.8% children experience Childhood Sexual Abuse (CSA) prior to the age of 18 (Stoltenborgh et al., 2011). However, the current prevalence rate of CSA is far underestimated due to the fear, shame, and denial that the victim experiences. Similarly, many survivors of CSA experience post-traumatic stress symptoms (PTSS) following the experience of CSA, which may develop into post-traumatic stress disorder (PTSD) over time. Furthermore, some children may adjust well despite the traumatic experience, suggesting resiliency. Much of the research on CSA focuses on the link between CSA and development of psychopathology, including but not limited …

An Integrated Model Of Optofluidic Biosensor Function And Performance, Joel Greig Wright, Jr.

Theses and Dissertations

Optofluidic flow-through biosensor devices have been in development for fast bio-target detection. Utilizing the fabrication processes developed by the microelectronics industry, these biosensors can be fabricated into lab-on-a-chip devices with a degree of platform portability. This biosensor technology can be used to detect a variety of targets, and is particularly useful for the detection single molecules and nucleic acid strands. Microfabrication also offers the possibility of production at scale, and this will offer a fast detection method for a range of applications with promising economic viability. The development of this technology has advanced to now warrant a descriptive model that …

Endeavors Toward Novel Synthetic Roadmaps In The Synthesis Of Pertinent Pharmacological Molecular Scaffold Moieties, Justin David Horgan

Theses and Dissertations

One of the main goals in the GML lab group is the development of novel, economical, and environmentally friendly organic methods for the synthesis of pharmacologically relevant molecular moieties. The most salient pieces of data to the GML lab group members, reading dependable organic journals, are finding organic moieties that are largely unexplored, finding organic moieties which various research groups are having difficulty synthesizing, and finding complex organic procedures to key organic structures that can be easily reduced, or reconstructed, into novel methods that are more economical and environmentally friendly. By looking at these unexplored molecules, as well as hard …

Insights Into Halophilic Microbial Adaptation: Analysis Of Integrons And Associated Genomic Structures And Characterization Of A Nitrilase In Hypersaline Environments, Sarah Sonbol

Theses and Dissertations

Hypersaline environments are extreme habitats that can be exploited as biotechnological resources. Here, we characterized a nitrilase (NitraS-ATII) isolated from Atlantis II Deep brine pool. It showed higher thermal stability and heavy metal tolerance compared to a closely related nitrilase.

We also studied integrons in halophiles and hypersaline environments. Integrons are genetic platforms in which an integron integrase (IntI) mediates the excision and integration of gene cassettes at specific recombination sites. In order to search for integrons in halophiles and hypersaline metagenomes, we used a PCR-based approach, in addition to different bioinformatics tools, mainly IntegronFinder.

We found that integrons and …

Heterogeneity In Multiple Inositol Polyphosphate Phosphatase1 (Minpp1): Identification And Characterization Of An Isoform-2 In Exosomes, Mohd Zubair

Theses and Dissertations

In pursuit of understanding the heterogeneity and physiological significance of multiple inositol polyphosphate phosphatase 1 (Minpp1), we have studied its isoforms for distinct motifs, subcellular distribution, and enzymatic potential. Initially, we took a Bioinformatics & Computational Biology approach exploring the proteome diversity of the Minpp1 utilizing the current NCBI database. We noticed three different minpp1 variants translated into three isoforms of Minpp1 proteins with varying molecular weight. A link between the minpp1 variant-2 gene and ER-stress, using real-time PCR, suggests a functional similarity between minpp1 variant-1 and variant-2. A detailed study on motifs revealed Minpp1 isoform-2 as the only other …

Drought-Tolerant Mechanisms Of Solanum Habrochaites, Dane Anthony Hudson

Theses and Dissertations

Understanding the complex mechanisms of drought tolerance in wild relatives of important crop plants offers a promising strategy for developing more stress resistant commercial cultivars. However, progress is limited by our understanding of the complex pathways involved in drought-tolerant phenotypes. This dissertation investigates and compares the biochemical and physiological effects of water deficit in a drought-tolerant wild tomato species (Solanum habrochaites) and a drought-sensitive commercial cultivar (Solanum lycopersicum cv. M82). M82 shows marked wilting reflected in low relative water content and water potential of the leaves, whereas S. habrochaites retains turgor, leaf water content, and high water potential levels. S. …

Another Time, Another Place: The Truth Of Silence In J.M. Coetzee's Disgrace, Sara T. Murphy

Theses and Dissertations

Through Lucy’s rejection of the criminal justice system, Coetzee's Disgrace operates as an allegory for the failure of the Truth and Reconciliation Commission to provide individual justice and reparations to victims of Apartheid.

The Mediating Role Of Interpersonal Skills In The Relationship Between Depressive Symptomatology And Dating Violence In Young Mothers, Lauren Catherine Wallace

Theses and Dissertations

Young mothers are an understudied group at high-risk for dating violence (DV) victimization and perpetration. Psychological distress, such as depression, increases young mothers' risk for DV (Thomas et al., 2019). In turn, depressive symptomology is associated with difficulties in interpersonal competence (Jones et al., 2019), which may increase DV risk (Bonache et al., 2017). In addition, young mothers may have few chances to learn the interpersonal skills associated with healthy adult romantic relationships due to a mismatch in developmental level and parenting status (Herrman et al., 2019; Moore et al., 2007). Using interpersonal stress generation theory (Hammen, 1991, 2006), we …

Inflammation And Altered Signaling In Obstetric Pathologies, Ya-Fang Tsai

Theses and Dissertations

The purpose of this research project was to elucidate the molecular interactions and detail the signaling pathways in obstetric pathologies. This work first seeks to understand inflammation related complications relevant to obstetrics. Prior research in our lab identified the implications of the receptor of advanced glycation end products (RAGE) during inflammatory response in the placenta. Current work identified the presence of DNA double-strand breaks (DNA-DSBs) in inflammation associated pregnancy complications of preeclampsia (PE) and preterm labor (PTL) and demonstrated the positive role of RAGE in repairing the damage. The confluent relevance of disrupted mitochondrial function and inflammation has been recognized …

Early & Late Erp Responses To L1 & L2 Emotion Words, Brenda Lizeth Guerrero

Theses and Dissertations

The thesis aims to explore bilingual emotion word processing. Participants performed a lexical decision task and decided whether presented letter strings displayed on the computer screen were legal words or nonwords. Stimuli consisted of positive emotion (i.e., hope), negative emotion (i.e., sad), and neutral (i.e., umbrella) words, as well as emotion-laden words (e.g. death, puppy). Reaction time and participant accuracy were collected as behavioral measures. In addition, participants’ electrophysiological responses were recorded. Specifically, the early posterior negativity (EPN) and late positive complex (LPC) components were recorded. Participants’ language dominance was measured using the Bilingual Dominance Scale (BDS) (Dunn & Fox-Tree, …

The Exploration Of Novel Synthetic Methods Of Biologically Relevant Nitrogen And Halogen Containing Molecules, Rebekah Erin Strong

Theses and Dissertations

Visible light has become a highly useful, and regarded, tool to the organic chemist. The additions and transformations of an abundance of molecules can be achieved with the use of visible light and photocatalysts, when appropriate. More specifically compounds that contain nitrogen, halogens, or both are highly useful structures in nearly every chemical industry. They are elements found in naturally occurring molecules and have the capacity to mimic biologically active and relevant structures. This makes them useful targets for pharmaceutical compounds. Bromine and chlorine can act as leaving groups; this property makes molecules with these elements reactive and thus able …

An Analysis Of Human Gait Under Slippery Conditions Using Opensim's Musculoskeletal Simulations, Phong K. Phan

Theses and Dissertations

Computational simulations of gait under abnormal conditions provide insights into the actions of muscles, its relationships with external reaction forces and motions of the body during slips, trips, and falls - the leading causes of occupational injuries worldwide. OpenSimTM, an open-source motion simulation software, was utilized to construct musculoskeletal structures and create dynamic simulations of body movements. Gaits of eighteen subjects were studied to extract experimentally difficult-to-obtained variables under slippery conditions. The joint angles and moments of hip, knee, ankle and the forces of four prime muscle groups were analyzed for body corrective movements during slip events. Besides, the connections …

Characterization Of 3d Printed Polyester Scaffolds Modified By Nano-Hydroxyapatite For Bone Tissue Engineering, Weitong Chen

Theses and Dissertations

Characterization of 3D printed polyester scaffolds modified by nano-hydroxyapatite for bone tissue engineering

Fathers As Stay-At-Home Dads: Fathers' And Mothers' Perspectives On Children's School Experiences, Taylor Hubbert Michelsen

Theses and Dissertations

As traditional family roles change and circumstances at home become increasingly varied in contemporary society, the experiences of children also undergo change. For instance, when fathers take on primary caregiving responsibilities, those differing circumstances also impact their children. Therefore, it is important for researchers to study how changing parental roles affect children in the home. Through the use of qualitative research design, this research focuses on how the experiences of children within the home may be impacted when fathers are the primary caregiver. Although previous research has examined several aspects of family dynamics with so-called stay-at-home fathers, research has not …

The Beneficial Effects Of The Gut-Derived Metabolite Trimethylamine N-Oxide On Functional Β-Cell Mass, Emily Suzanne Krueger

Theses and Dissertations

Elevated serum levels of trimethylamine N-oxide (TMAO) were first associated with increased risk of cardiovascular disease (CVD) 10 years ago. Research has since defined that serum TMAO accumulation is controlled by the diet-microbiome-liver-kidney axis. Choline related nutrients are consumed in excess during over-nutrition from a Western diet. The resultant elevated serum TMAO is investigated across various chronic metabolic diseases and many tissue types. While TMAO is most clearly linked to CVD mechanisms in vascular tissue, its molecular effects on metabolic tissues are unclear. Here we report the current standing of TMAO research in metabolic disease context across relevant metabolic tissues …

Designing Cell-Free Protein Synthesis Systems For Improved Biocatalysis And On-Demand, Cost-Effective Biosensors, Mehran Soltani Najafabadi

Theses and Dissertations

The open nature of Cell-Free Protein Synthesis (CFPS) systems has enabled flexible design, easy manipulation, and novel applications of protein engineering in therapeutic production, biocatalysis, and biosensors. This dissertation reports on three advances in the application of CFPS systems for 1) improving biocatalysis performance in industrial applications by site-specific covalent enzyme immobilization, 2) expressing and optimizing a difficult to express a mammalian protein in bacterial-based CFPS systems and its application for cost-effective, on-demand biosensors compatible with human body fluids, and 3) streamlining the procedure of an E. coli extract with built-in compatibility with human body fluid biosensors. Site-specific covalent immobilization …

Immunoaffinity Monoliths For Multiplexed Extraction Of Preterm Birth Biomarkers From Human Blood Serum In 3d Printed Microfluidic Devices, Haifa Mohammad Almughamsi

Theses and Dissertations

Preterm birth (PTB) results in over 15 million early births annually and is the leading cause of neonatal deaths. There are no clinical methods currently available to evaluate risk of PTB at early stages in pregnancy; thus, a rapid diagnostic to analyze PTB risk would be beneficial. Microfluidic immunoaffinity extraction is a promising platform for preparing complex samples, such as maternal serum with PTB risk biomarkers. 3D printed microfluidic devices have advantages over conventional microfluidic systems including simple fabrication and potential for iterative optimization to improve designs. In this work, I developed immunoaffinity monoliths in 3D printed microfluidic devices modified …