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Full-Text Articles in Engineering
Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood
Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood
McKelvey School of Engineering Theses & Dissertations
This thesis explores the micromechanical environment induced when cyclically compressing hydrogels via finite element modeling and experimentally on the impact of loading on mesenchymal stem cells (MSCs) when encapsulated withing 3D hydrogel matrices. Degenerative joint diseases, characterized by cartilage degradation, present significant challenges due to cartilage's limited self-repair capacity. Innovative approaches, including stem cell-based therapies and engineered biomaterials, have emerged as promising strategies for cartilage repair and regeneration. This work specifically investigates the calibration of a bioreactor, the uniformity of load response across the hydrogel constructs via finite element modeling (FEM), and the stress response of MSCs subjected to various …
Prolonged Exposure To Microgravity Increases Susceptibility To Traumatic Brain Injury, Ryan Baskerville
Prolonged Exposure To Microgravity Increases Susceptibility To Traumatic Brain Injury, Ryan Baskerville
UNF Graduate Theses and Dissertations
With the prospect of semi-permanent and permanent habitable fixtures on the moon and Mars, the complications associated with long-term exposure to microgravity should be investigated exhaustively. Spaceflight Associated Neuro-Ocular Syndrome (SANS), a group of neurological and ocular effects resulting from prolonged exposure to microgravity, is characterized by significant fluid shifts into the cranium, namely cerebrospinal fluid and blood, and an upward shift of the brain relative to the skull. This syndrome, along with its immediate effects on visual acuity, cognitive ability, and motor function are recognized by NASA, but its effects on susceptibility to traumatic brain injury have yet to …
Multiscale Finite Element Modeling Of Active Contraction In Striated Muscle, Charles Kurtis Mann
Multiscale Finite Element Modeling Of Active Contraction In Striated Muscle, Charles Kurtis Mann
Theses and Dissertations--Mechanical Engineering
Greater than one in three American adults have at least one type of cardiovascular disease, a major cause of morbidity. Computational cardiac mechanics has become an important part of the research effort to understand the heart’s response to mechanical stimuli and as an extension, disease progression and potential therapies. To this end, the present work aims to extend these efforts by implementing a cell level contractile model in which active stress generation in muscle tissue is driven by half-sarcomere mechanics. This is accomplished by enhancing the MyoSim model of actin and myosin in order to produce a multiscale model. This …
Understanding The Effects Of Long-Duration Spaceflight On Fracture Risk In The Human Femur Using Finite Element Analysis, Keyanna Brielle Henderson
Understanding The Effects Of Long-Duration Spaceflight On Fracture Risk In The Human Femur Using Finite Element Analysis, Keyanna Brielle Henderson
Master's Theses
Long-duration spaceflight has been shown to have significant, lasting effects on the bone strength of astronauts and to contribute to age-related complications later in life. The microgravity environment of space causes a decrease in daily mechanical loading, which signals a state of disuse to bone cells. This affects the bone remodeling process, which is responsible for maintaining bone mass, causing an increase in damage and a decrease in density. This leads to bone fragility and decreases overall strength, posing a risk for fracture. However, there is little information pertaining to the timeline of bone loss and subsequent fracture risk.
This …
Quantification Of Papillary Muscle Motion And Mitral Regurgitation After Myocardial Infarction, Connor R. Ferguson
Quantification Of Papillary Muscle Motion And Mitral Regurgitation After Myocardial Infarction, Connor R. Ferguson
Theses and Dissertations--Mechanical Engineering
Change in papillary muscle motion as a result of left ventricular (LV) remodeling after posterolateral myocardial infarction is thought to contribute to ischemic mitral regurgitation. A finite element (FE) model of the LV was created from magnetic resonance images acquired immediately before myocardial infarction and 8 weeks later in a cohort of 12 sheep. Severity of mitral regurgitation was rated by two-dimensional echocardiography and regurgitant volume was estimated using MRI. Of the cohort, 6 animals (DC) received hydrogel injection therapy shown to limit ventricular remodeling after myocardial infarction while the control group (MI) received a similar pattern of saline injections. …
Experimental, Analytical, And Numerical Evaluation Of The Mechanical Properties Of The Brain Tissue, Aref Samadidooki
Experimental, Analytical, And Numerical Evaluation Of The Mechanical Properties Of The Brain Tissue, Aref Samadidooki
LSU Doctoral Dissertations
A true understanding of the mechanisms behind most of the brain diseases is still out of reach. For several years, the interest of scientists has been focused on the genetic and biological causes, however, recent studies unraveled the importance of the biomechanics of the brain growth, folding, impact resistance, and deformation on its pathological conditions. While, a wide range of different methods have been used for characterization of the mechanical properties of the brain at the tissue level, the obtained results from different studies are extremely scattered and sometimes in contrast to one another. Since the brain tissue is extremely …
Computational Investigation Of Transmural Differences In Left Ventricular Contractility And Hydrogel Injection Treatment For Myocardial Infarction, Hua Wang
Theses and Dissertations--Mechanical Engineering
Heart failure (HF) is one of the leading causes of death and impacts millions of people throughout the world. Recently, injectable hydrogels have been developed as a potential new therapy to treat myocardium infarction (MI). This dissertation is focused on two main topics: 1) to gain a better understanding the transmural contractility in the healthy left ventricle (LV) wall and 2) investigate the efficacy of the hydrogel injection treatment on LV wall stress and function. The results indicate that a non-uniform distribution of myocardial contractility in the LV wall provide a better representation of normal LV function. The other important …
Morphology Of Brain Sulci Trabeculae And Its Effect On Brain During Impacts, Sharlin Anwar
Morphology Of Brain Sulci Trabeculae And Its Effect On Brain During Impacts, Sharlin Anwar
Dissertations and Theses
Traumatic brain injury (TBI) is an intracranial injury caused by direct contact or non-contact head impacts to the brain. TBI is a major problem that accounts for high incidents of hospitalizations each year. Thus, it is important to understand and predict the occurrence of TBI in an impact. It has been shown that the subarachnoid space (SAS) trabeculae play an important role in damping the effect of an impact, thus reducing the injuries. However, the influence of sulci parameters and the sulci trabeculae in TBI due to impact is unexplored. Studies have shown that inclusion of sulci in brain models …
Computational Modeling Of Cardiac Biomechanics, Amir Nikou
Computational Modeling Of Cardiac Biomechanics, Amir Nikou
Theses and Dissertations--Mechanical Engineering
The goal of this dissertation was to develop a realistic and patient-specific computational model of the heart that ultimately would help medical scientists to better diagnose and treat heart diseases. In order to achieve this goal, a three dimensional finite element model of the heart was created using magnetic resonance images of the beating pig heart. This model was loaded by the pressure of blood inside the left ventricle which was measured by synchronous catheterization. A recently developed structurally based constitutive model of the myocardium was incorporated in the finite element solver to model passive left ventricular myocardium. Additionally, an …
Estimating Passive Material Properties And Fiber Orientation In A Myocardial Infarction Through An Optimization Scheme Using Mri And Fe Simulation, Dimitri Mojsejenko
Estimating Passive Material Properties And Fiber Orientation In A Myocardial Infarction Through An Optimization Scheme Using Mri And Fe Simulation, Dimitri Mojsejenko
Theses and Dissertations--Mechanical Engineering
Myocardial infarctions induce a maladaptive ventricular remodeling process that independently contributes to heart failure. In order to develop effective treatments, it is necessary to understand the way and extent to which the heart undergoes remodeling over the course of healing. There have been few studies to produce any data on the in-vivo material properties of infarcts, and much less on the properties over the time course of healing. In this paper, the in-vivo passive material properties of an infarcted porcine model were estimated through a combined use of magnetic resonance imaging, catheterization, finite element modeling, and a genetic algorithm optimization …
Finite Element Modeling And Fabrication Of An Sma-Smp Shape Memory Composite Actuator, Mohammad Souri
Finite Element Modeling And Fabrication Of An Sma-Smp Shape Memory Composite Actuator, Mohammad Souri
Theses and Dissertations--Mechanical Engineering
Shape memory alloys and polymers have been extensively researched recently because of their unique ability to recover large deformations. Shape memory polymers (SMPs) are able to recover large deformations compared to shape memory alloys (SMAs), although SMAs have higher strength and are able to generate more stress during recovery.
This project focuses on procedure for fabrication and Finite Element Modeling (FEM) of a shape memory composite actuator. First, SMP was characterized to reveal its mechanical properties. Specifically, glass transition temperature, the effects of temperature and strain rate on compressive response and recovery properties of shape memory polymer were studied. Then, …
Predicting Articular Cartilage Constituent Material Properties Following In Vitro Growth Using A Proteoglycan-Collagen Mixture Model, Michael Stender
Predicting Articular Cartilage Constituent Material Properties Following In Vitro Growth Using A Proteoglycan-Collagen Mixture Model, Michael Stender
Master's Theses
A polyconvex continuum-level proteoglycan Cauchy stress function was developed based on the continuum electromechanical Poisson-Boltzmann unit cell model for proteoglycan interactions. The resulting proteoglycan model was combined with a novel collagen fibril model and a ground substance matrix material to create a polyconvex constitutive finite element model of articular cartilage. The true collagen fibril modulus , and the ground substance matrix shear modulus , were varied to obtain the best fit to experimental tension, confined compression, and unconfined compression data for native explants and explants cultured in insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1). Results indicate …