Degree Discipline

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Viability Study of Nylon-12 Carbon Fiber Filaments for Use in the Construction of a Powered Lower Body Exoskeleton via Fused Deposition Modeling by Means of Computer Simulation (open access)

Viability Study of Nylon-12 Carbon Fiber Filaments for Use in the Construction of a Powered Lower Body Exoskeleton via Fused Deposition Modeling by Means of Computer Simulation

Members of the elderly population is disproportionately prone to experiencing mobility impairment due to their aging bodies and as a result have frail bodies that are at a higher risk of grave injury due to falling. In order to combat this assistive mobility devices such as exoskeletons have been developed to help patients enhance their range of motion. With additive manufacturing techniques, such as fused deposition modeling (FDM), becoming a more mainstream form of design, the inclusion of lightweight polymers such as nylon 12 as primary construction materials for these devices has increased. In this thesis computer aided design (CAD) software was used to design a prototype lower body exoskeleton and simulation software was used to give the device the characteristics of Stratasys' nylon 12 carbon fiber FDM material to verify it if could be used as the primary construction material for this device when extruded from a FDM printer on either the XZ or ZX printing plane. From the simulations it was found that the material printed along the XZ plane could create a device that could withstand the weight of an average elderly male patient (200 lbs.) as well as the 35 lbs. of force applied to the …
Date: May 2021
Creator: Joiner, Michael Andrew Lown
System: The UNT Digital Library
Parkinson's Disease and UPDRS-III Prediction Using Quiet Standing Data and Applied Machine Learning (open access)

Parkinson's Disease and UPDRS-III Prediction Using Quiet Standing Data and Applied Machine Learning

Parkinson's disease (PD) is a neurodegenerative disease that affects motor abilities with increasing severity as the disease progresses. Traditional methods for diagnosing PD require specialists scoring qualitative symptoms using the motor subscale of the Unified Parkinson's Disease Rating Scale (UPDRS-III). Using force-plate data during quiet standing (QS), this study uses machine learning to target the characterization and prediction of PD and UPDRS-III. The purpose of predicting different subscores of the UPDRS-III is to give specialists more tools to help make an informed diagnosis and prognosis. The classification models employed classified PD with a sensitivity of 87.5% and specificity of 83.1%. Stepwise forward regression indicated that features correlated with base of support were most useful in the prediction of head rigidity (r-square = .753). Although there is limited data, this thesis can be used as an exploratory study that evaluates the predictability of UPDRS-III subscores using QS data. Similar prediction models can be implemented to a home setting using low-cost force plates as a novel telemedicine technique to track disease progression.
Date: May 2021
Creator: Exley, Trevor Wayne
System: The UNT Digital Library
Effects of Attachment Height and Rail Material of Resistance Training Sled on Trunk Lean and Jerk During Linear Acceleration Training (open access)

Effects of Attachment Height and Rail Material of Resistance Training Sled on Trunk Lean and Jerk During Linear Acceleration Training

Sprint acceleration training has been highly researched and found that resistance sleds are one of the most effective tools for maximizing training adaptations. The resistance sled is being used by many of the world leaders in athletic training but has yet to be researched for the kinetic and kinematic effects some of its key components cause. The aim of this study was to better understand the effects of the attachment height on the sled and sled rail material on the user's trunk lean and jerking effect caused by the sled. This was done because it was hypothesized that the attachment height has a direct impact on trunk lean and sled rail material has a direct impact on jerk caused by the sled. To test these assumptions, experimental and theoretical data was collected using a single subject study analyzing trunk lean and acceleration values of the sled. The results presented a significant decrease in trunk lean (more horizontal line of action) when the attachment height was raised. Additionally, no significant values were attained to support the assumption that by modifying the sled rail material, jerking effects will decrease. The results indicate that there is a direct correlation between attachment height and …
Date: May 2021
Creator: Fitzgerald, Sean
System: The UNT Digital Library

Nanolithographic Approaches to Probing Cell Membrane Modulation

Metastatic cancer is more dangerous and difficult to treat than pre-metastatic cancer. Ninety percent of cancer-related deaths are caused by metastatic cancer. When cells go through metastases, they go through changes that allow them to break away from the primary tumor and invade secondary tissues. These changes, in lipid membrane composition and cellular glycocalyx, make the cell more resistant to therapeutics. Actin cytoskeleton contractility plays a major role in these changes, as increased contractility has been linked to upregulation of phosphoinositides and production of glycoproteins. Light induced molecular adsorption of proteins (LIMAP) was used to control the actin arrangement and cell shape in order to mimic and study metastatic cells. Negatively charged proteins electrostatically adhere to the surface in order to create patterns for the cells to stick. Neutravidin was conjugated to poly(glutamic acid) to improve attachment to the surface. We observed differences in cell shape and phosphoinositide behavior based on LIMAP patterning. Additionally, expression of key glycoproteins related to cancer metastasis increased with increased actin contractility. The actin cytoskeleton was the main driver of changes to the cell membrane and glycocalyx.
Date: May 2022
Creator: Mathis, Katelyn
System: The UNT Digital Library
Modeling Hypertrophic Cardiomyopathy Using Genome-Edited Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Response to Dynamic Mechanotransduction (open access)

Modeling Hypertrophic Cardiomyopathy Using Genome-Edited Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Response to Dynamic Mechanotransduction

Familial hypertrophic cardiomyopathy (HCM) is a genetic disease largely caused by a mutation in myosin binding protein C (MYBPC3) and it affects about 1:500 population leading to arrhythmic sudden death, heart failure, and atrial fibrillation. MYBPC3 activates calcium-induced actin-myosin filament sliding within the cardiac sarcomere, creating the force necessary for heart contraction. The underlying molecular mechanisms causing HCM phenotype remain elusive, therefore, there is an urgent need for a reliable in vitro human HCM model to investigate the pathogenesis of HCM. This study utilized isogenic human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with MYBPC3 gene mutation (wildtype, heterozygous, homozygous) and further micropatterned them into fiber-like structures on polyacrylamide hydrogels of physiological and fibrotic-like stiffnesses. Cells were cultured for an extended culture time up to 60 days and their morphology/attachment, contractility, and calcium transient were extensively and carefully evaluated. It was found that MYBPC3 knockout cells maintained the highest contraction amplitude, but had increased contraction, and relaxation durations, decreased calcium transient amplitude, as well as time to peak and decay times over the culture period in comparison to the isogenic wildtype. Overall, this study demonstrates that hiPSC-CMs can be successfully patterned and cultured for an extended time on hydrogels forming end-to-end …
Date: May 2022
Creator: Strimaityte, Dovile
System: The UNT Digital Library
Engineering Whole Cell-Based Biosensors for Heavy Metal Detection Using Metalloregulatory Transcriptional Repressors of the SmtB/ArsR Family (open access)

Engineering Whole Cell-Based Biosensors for Heavy Metal Detection Using Metalloregulatory Transcriptional Repressors of the SmtB/ArsR Family

This study focuses on engineering whole cell-based biosensors for heavy metal detection. Through the exploitation of metalloregulatory proteins, fabrication of metal ion-responsive biosensors is achieved. Metalloregulatory proteins of the SmtB/ArsR family including arsenite-responsive ArsR, cadmium-responsive CadC, zinc-responsive CzrA, and nickel-responsive NmtR were evaluated as biosensor sensing modules. Characterization of these four metal sensing modules was accomplished through quantification of a reporter green fluorescence protein (gfp) gene. As such, biosensors pCTYC-r34ArsR-pL(ArsOvN)GFP and pCTYC-r34CadC-pL(CadOv1)GFP displayed excellent gfp expression and sensitivity to As(III) and Cd (II), respectively. These two biosensors were consequently selected and successfully implemented in soil bacterium Pseudomonas putida. Lastly, a proof of concept arsenite-responsive genetic toggle switch is proposed utilizing PurRcelR467 (PC47), a cellobiose-responsive gene, and an LAA degradation tag. Overall, this study expands the bank of metalloregulatory bioparts for heavy metal sensing in the aim of constructing an optimized water monitoring system.
Date: May 2022
Creator: Draeger, Alison
System: The UNT Digital Library

Development of Biomimetic Human Lung Alveolus Chip

The potential of physiologically relevant in vitro cell culture models for studying physiological and pathophysiological phenomena has been widely recognized as replacements for animal and conventional in vitro models. To create models that accurately replicate the structure and function of tissues and organs, it is essential to comprehend the biophysical and mechanical features of the extracellular matrix (ECM) and incorporate them into the in vitro cell culture models. Therefore, we first aimed to investigate how nanotopography can modulate cell behaviors by studying cell behaviors on nanostructures of various aspect ratios on a cobalt-chromium-molybdenum (CoCrMo) alloy surface. We also explored the impact of nanofibrous membranes on the formation of alveolar epithelium, which is critical for lung alveolar interstitium chips. In addition, we investigated the effect of mechanical stretch on cell behaviors and focused on how the dimensionality of the stretch affects cell behaviors. To create physiologically relevant in vitro models based on our findings, we engineered a stem cell niche using a combination of nanofibrous membranes, mechanical stretch, and a soft substrate, and evaluated its impact on stem cell behaviors. Finally, we created a biomimetic human lung interstitium chip for application in physiological and pathophysiological in vitro studies.
Date: May 2023
Creator: Man, Kun
System: The UNT Digital Library
Modeling of Hypertrophic Cardiomyopathy Using hiPSC-Derived Cardiomyocytes with Static Mechanical Stretching (open access)

Modeling of Hypertrophic Cardiomyopathy Using hiPSC-Derived Cardiomyocytes with Static Mechanical Stretching

The heart is a dynamic environment that is constantly experiencing some degree of remodeling from the point of development, all the way through adulthood. While many genetic components may contribute to the overall presentation of hypertrophic cardiomyopathy (HCM), mutations occurring in sarcomere components such as myosin binding protein C3 (MYBPC3) are of the greatest popularity for study. Aiming to understand the mechanisms underlying heart diseases and to develop effective treatments that circumvent the need for direct patient study, we investigated the use of a platform to mimic the unique physiological conditions of HCM within an in-vitro setting. Following the induction of mechanical stretch on three human induced pluripotent stem cell derived cardiomyocyte (hiPSC-CM) cell lines containing mutations for MYBPC3 (WT, HET, HOM), all displayed HCM like reactions in calcium waveform. In conclusion, this system demonstrated the potential to apply a constant, static strain to healthy and mutated hiPSC-CMs for the MYBPC3 protein to model HCM in-vitro.
Date: May 2023
Creator: Rogozinski, Nicholas
System: The UNT Digital Library