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Full-Text Articles in Engineering

High Quality Molecular Beam Epitaxy Growth And Characterization Of Lead Titanate Zirconate Based Complex-Oxides, Xing Gu Dec 2007

High Quality Molecular Beam Epitaxy Growth And Characterization Of Lead Titanate Zirconate Based Complex-Oxides, Xing Gu

Theses and Dissertations

Research interest in complex oxides has resurged owing to progress in modern epitaxial techniques. Among such oxides, lead-titanate-based thin films such as PbTiO3 (PTO) and Pb(ZrxTi1−x)O3 (PZT) offer attractive advantages for a wide variety of applications. Moreover, integration between functional oxides with compound semiconductors has the potential to realize multi-functional devices which enjoy the properties from both groups of materials. Ferroelectric materials with a perovskite structure (ABO3) and semiconductors such as GaN with a hexagonal structure, require a careful choice of a bridge layer and suitable epitaxial technique. Molecular beam epitaxy (MBE) …


Development And Validation Of A Computational Musculoskeletal Model Of The Elbow Joint, Justin Paul Fisk Jan 2007

Development And Validation Of A Computational Musculoskeletal Model Of The Elbow Joint, Justin Paul Fisk

Theses and Dissertations

Musculoskeletal computational modeling is a versatile and effective tool which may be used to study joint mechanics, examine muscle and ligament function, and simulate surgical reconstructive procedures. While injury to the elbow joint can be significantly debilitating, questions still remain regarding its normal, pathologic, and repaired behavior. Biomechanical models of the elbow have been developed, but all have assumed fixed joint axes of rotation and ignored the effects of ligaments. Therefore, the objective of this thesis was to develop and validate a computational model of the elbow joint whereby joint kinematics are dictated by three-dimensional bony geometry contact, ligamentous constraints, …


The Lynks Reader, Anne Marie Reamey Jan 2007

The Lynks Reader, Anne Marie Reamey

Theses and Dissertations

Many adults and children have problems reading and comprehending books, signs, written directions, etc. These same individuals have difficulty processing written materials as a result of right hemisphere interference. The Lynks Reader (DLR Co., Richmond, VA) is a commercially developed device which has been used to help individuals move from their right to their left hemisphere and to increase reading fluency and comprehension. The objective of this project was to evaluate the best way to use the various forms of the Lynks Reader. Using the device demonstrated an increase in reading fluency and comprehension by increasing the left hemisphere dominance. …


Low Dislocation Density Gallium Nitride Templates And Their Device Applications, Jinqiao Xie Jan 2007

Low Dislocation Density Gallium Nitride Templates And Their Device Applications, Jinqiao Xie

Theses and Dissertations

The unique properties, such as large direct bandgap, excellent thermal stability, high μH × ns, of III-nitrides make them ideal candidates for both optoelectronic and high-speed electronic devices. In the past decades, great success has been achieved in commercialization of GaN based light emitting diodes (LEDs) and laser diodes (LDs). However, due to the lack of native substrates, thin films grown on sapphire or SiC substrates have high defect densities that degrade the device performance and reliability. Conventional epitaxy lateral overgrowth (ELO) can reduce dislocation densities down to ∼10-6 cm-2 in the lateral growth area, but requires ex situ photolithography …


Design Of An Electrospun Type Ii Collagen Scaffold For Articular Cartilage Tissue Engineering, Catherine Pemble Barnes Jan 2007

Design Of An Electrospun Type Ii Collagen Scaffold For Articular Cartilage Tissue Engineering, Catherine Pemble Barnes

Theses and Dissertations

Traumatic defects in articular cartilage can lead to joint disease and disability including osteoarthritis. Because cartilage is unable to regenerate when injured, the field of tissue engineering holds promise in restoring functional tissue. In this research, type II collagen was electrospun, cross-linked, and tested as scaffolds for supporting chondrocyte growth. The mechanical, biochemical, and histological characteristics of the engineered tissue were assessed as a function of the electrospinning solution concentration (i.e. scaffold fiber diameter and pore properties) and as a function of the time in culture (evaluated at 2, 4, and 6 weeks). Fiber diameter had a linear relationship with …


The Development Of A Multi-Directional Wear Apparatus And The Characterization And Correlation Of Biomechanical And Biotribological Properties Of Bovine Articular Cartilage, Kelly J. Shields Jan 2007

The Development Of A Multi-Directional Wear Apparatus And The Characterization And Correlation Of Biomechanical And Biotribological Properties Of Bovine Articular Cartilage, Kelly J. Shields

Theses and Dissertations

A multi-directional wear apparatus was developed to simulate the kinematic motion of diarthrodial joints. A comprehensive evaluation including biotribological and biomechanical characterization of articular surfaces was performed with concomitant translational and oscillating rotational motion similar to that experienced in vivo. Various system parameters were evaluated in the designed experiments including normal load magnitude (high/low), surface quality (defect/no defect), and wear pattern (with/without rotation). Biomechanical characterization was achieved through stress relaxation and dynamic cyclical testing. Quasi-linear viscoelastic theory was used to curve-fit the stress relaxation data, while the dynamic data was used to determine the dynamic properties through Fast Fourier Transform …