Digital Commons Network^™

Synthesis And Physical Properties Of High Entropy Oxide Ceramics, Brianna L. Musicó

Doctoral Dissertations

Utilizing entropy as the driving force for stabilizing oxide materials offers a path for the discovery of innovative compounds with unique structure-property relations. The multi-cation approach inherent to high entropy oxides (HEOs) is expected to allow for the tailoring of physical properties that meet the requirements of potential applications. However, the intrinsic disorder and highly localized chemical environments of HEOs bring along new challenges. In order to shed light on the complexities associated multi-cation oxides, we have initiated a systematic study of polycrystalline HEO samples across multiple crystal systems. This work expands the multi-component concept to new compositions and crystal …

Efficacy Of A Cycling Intervention With Pedal Reaction Force Augmented Feedback On Reducing Inter-Limb Asymmetries In Patients With Unilateral Total Knee Arthroplasty, Erik T. Hummer

Doctoral Dissertations

Fifteen patients with unilateral total knee arthroplasty (TKA) performed cycling at two workates (80 W and 100 W) and two walking conditions (preferred and fast speeds). Ten of these patients of TKA also participated in a short-term cycling intervention paired with visual augmented feedback of vertical pedal reaction forces for six sessions over two-three weeks. These ten patients of TKA participated in a 2^nd post-training testing session. Study One compared the knee joint biomechanics for all fifteen participants during stationary cycling to ascertain if any biomechanical asymmetries may be present. The replaced limbs displayed significantly lower peak knee extension …

Membrane And Performance Study In Polymer Electrolyte Membrane Fuel Cells And Hydrogen Bromine Redox Flow Batteries, Yujia Bai

Doctoral Dissertations

This dissertation represents the consideration of the problems of polymer electrolyte membrane fuel cells (PEMFC) and hydrogen-bromine redox flow batteries (RFB). Due to the importance of water management in PEMFCs, all the experiments were strictly controlled at different water hydration conditions. Water uptake and densities were measured for Nafion^® and a series of 3M ionomer membranes. The thermodynamics of water and polymer was analyzed based on water uptake experiment and calorimetry. Furthermore, partial molar volumes (PMV) of water/membrane system was defined for the first time and used to analyze the interaction between water and polymers. Three states of water …

Development Of A Computational Methodology For Evaluating In Vivo Vertebral Mechanics In Subjects Having Various Conditions Of The Lumbar Spine, Christopher Brian Carr

Doctoral Dissertations

Treating and evaluating the causes of low back pain (LBP) is difficult and not fully understood. However, assessing the in vivo motions and loading characteristics in the lumbar spine may provide important data for progressing the diagnosis and treatment of pathologies linked with LBP.

This dissertation describes the development of a comprehensive approach for collecting both the kinematics and kinetics of the lumbar vertebrae under in vivo conditions. Forty-four subjects representing healthy, symptomatic, pathological, and surgically implanted (pre- and post-operative) conditions of the lumbar spine were evaluated using dynamic fluoroscopy and 3D-to-2D image registration to assess the motions of the …

Kinetic And Kinematic Evaluation Of Compensatory Movements Of The Head, Pelvis And Thoraco-Lumbar Spine Associated With Asymmetrical Weight Bearing Of The Pelvic Limbs In Dogs, David Alan Hicks

Doctoral Dissertations

The purposes of this dissertation were to 1) determine ground reaction forces of dogs with mild asymmetrical weight-bearing of the pelvic limbs while trotting and 2) use three-dimensional motion analysis to identify compensatory vertical motion of the head and pelvis, and lateral motion of the thoraco-lumbar spine in dogs with mild asymmetrical weight-bearing of the pelvic limbs while trotting, and 3) use this information to introduce a subjective grading system for the pelvic limbs in dogs. Our hypotheses were that dogs with asymmetric weight bearing demonstrate compensatory motions of the head, pelvis and thoraco-lumbar spine while trotting, and that these …

Effects Of Increased Step Width On Knee Joint Biomechanics In Healthy And Knee Osteoarthritis Older Adults During Stair Descent, Maxime Robert Paquette

Doctoral Dissertations

Stair negotiation is one of the most challenging tasks for older adults especially for those suffering from knee osteoarthritis (OA). To date, no studies have investigated the effects of increased step width (SW) on knee joint biomechanics. The purpose of Study One was to investigate the effects of increased SW on peak internal knee abduction moment and other lower extremity variables during stair descent in healthy older adults. The purpose of Study Two was to investigate the effects of increased SW on peak internal knee abduction moment, knee pain and other lower extremity variables during stair descent in medial compartment …

Dynamics, Electromyography And Vibroarthrography As Non-Invasive Diagnostic Tools: Investigation Of The Patellofemoral Joint, Filip Leszko

Doctoral Dissertations

The knee joint plays an essential role in the human musculoskeletal system. It has evolved to withstand extreme loading conditions, while providing almost frictionless joint movement. However, its performance may be disrupted by disease, anatomical deformities, soft tissue imbalance or injury. Knee disorders are often puzzling, and accurate diagnosis may be challenging. Current evaluation approach is usually limited to a detailed interview with the patient, careful physical examination and radiographic imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissue conditions. More advanced imaging tools such as MRI or CT are available, …

Spatially-Dependent Reactor Kinetics And Supporting Physics Validation Studies At The High Flux Isotope Reactor, David Chandler

Doctoral Dissertations

The computational ability to accurately predict the dynamic behavior of a nuclear reactor core in response to reactivity-induced perturbations is an important subject in the field of reactor physics. Space-time and point kinetics methodologies were developed for the purpose of studying the transient-induced behavior of the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor’s (HFIR) compact core. The space-time simulations employed the three-group neutron diffusion equations, which were solved via the COMSOL partial differential equation coefficient application mode. The point kinetics equations were solved with the PARET code and the COMSOL ordinary differential equation application mode. The basic nuclear …

Development Of A Rigid Body Forward Solution Physiological Model Of The Lower Leg To Predict Non Implanted And Implanted Knee Kinematics And Kinetics, John Kyle Patrick Mueller

Doctoral Dissertations

This dissertation describes the development and results of a physiological rigid body forward solution mathematical model that can be used to predict normal knee and total knee arthroplasty (TKA) kinematics and kinetics. The simulated activities include active extension and weight-bearing deep knee bend. The model includes both the patellofemoral and tibiofemoral joints. Geometry of the normal or implanted knee is represented by multivariate polynomials and modeled by constraining the velocity of lateral and medial tibiofemoral and patellofemoral contact points in a direction normal to the geometry surface.

Center of mass, ligament and muscle attachment points and normal knee geometry were …

Biomechanical Risk Factors For Knee Osteoarthritis In Young Adults: The Influence Of Obesity And Gait Instruction, Julia Ann Freedman

Doctoral Dissertations

With increasing rates of obesity, research has begun to focus of co-morbidities of obesity such as osteoarthritis. The majority of existing research has focused on older adults as the group most likely to suffer from osteoarthritis. The purpose of this study was to determine if overweight and obese young adults exhibit biomechanical risk factors for knee osteoarthritis, and to determine if young adults with biomechanical risk factors of osteoarthritis can modify these with instruction. This purpose was divided into two separate studies.

Study 1: Thirty adults between 18-35 years old were recruited into three groups according to body mass index: …