The purpose of this thesis was to understand the implications of ultrasound in the assessment of flexor tendon shear to establish its role in carpal tunnel syndrome. An in vitro and in vivo approach was used to examine ultrasound “shear” between the tendon and adjacent tenosynovium. Ultrasound shear is defined by the relative displacement between the tendon and tenosynovium, and has been considered a surrogate measure of tendon shear. However, the mechanical implications of relative displacement are not well understood. In Chapters 2 and 3, an in vitro approach was used to compare ultrasound to direct measurements of tendon displacement and tendon shear. Chapter 2 demonstrated the validity of colour Doppler ultrasonography in the evaluation of tendon displacement. Chapter 3 assessed the relationship between ultrasound shear and mechanical tendon shear using frictional work. We dispelled the notion that ultrasound shear represents tendon shear by showing it only captures the viscoelastic stretch of the tenosynovium in tendon shear; missing surface friction from neighbouring anatomical structures in the carpal tunnel. However, measuring viscoelastic resistance in tendon motion is important for the development of pathological fibrosis and thickening of the tenosynovium, a characteristic finding in carpal tunnel syndrome. In Chapter 4 we further established the clinical utility of ultrasound in vivo by showing ultrasound shear discriminated carpal tunnel syndrome symptomatic individuals from the healthy population. Ultrasound measures progressed with symptoms suggesting an etiological progression of fibrosis and thickening with carpal tunnel syndrome. This thesis concluded that ultrasound only partially represents tendon shear with the viscoelastic component, but underscored the clinical implications. Ultrasound provides a non-invasive assessment of viscoelastic resistance that will be highly valuable for our understanding of the role of wrist and hand motion in the etiology of injury with potential applications in the diagnosis of carpal tunnel syndrome. / Thesis / Master of Science in Kinesiology

<p> The development and properties of carbon fibre are reviewed together with the properties and applications of carbon fibre reinforced plastic. Techniques for fabricating this material and certain design problems are discussed and future developments considered.</p> <p> Some simple predictions of the elastic moduli of fibre reinforced composites are compared with experimental data and a modification for the prediction of the longitudinal shear modulus suggested. Typical values for the elastic moduli of carbon fibre reinforced plastic are presented.</p> <p> A method for predicting the behaviour of laminated composite structures, which is more realistic than conventional netting analysis, is described and a computer programme for determining the strength and stiffness of such structures included.</p> / Thesis / Master of Engineering (MEngr)

<p> A high-pressure nitrogen-driven viscometer has been used to study the melt fracture of polystyrene. The polystyrene samples used differed in molecular weight and molecular weight distribution. The weight average molecular weight (Mw) ranged from 97,200 to 1.8 x 10^6 and the distribution breadth (Mw/Mn) from 1.06 to 9.21. Results obtained indicate that the critical shear stress varies linearly with 1/Mw, increases slightly with temperature and is independent of the polydispersity of polymers. This type of behaviour is satisfactorily explained in terms of Graessley's entanglement theory.</p> / Thesis / Master of Engineering (MEngr)

Abrasive finishing is a machining process which alters the surface of a workpiece to achieve a specific property. Typical abrasive finishing processes focus on geometric tolerances and surface topography. Abrasive finishing is primarily dependent on finishing forces, relative velocities, and abrasive size. The material removal rate in finishing is inversely related to the surface finish. Magnetic and electric fields have been used to control the force applied to abrasives which finish the workpiece. These processes show an increase in performance when the field is used to control the process. Field assisted finishing processes can be energy intensive and expensive. A novel finishing media is proposed which does not require a field to achieve a similar force response. This media has inherent thickening mechanisms driven by shear jamming. This shear jamming mechanism can deliver forces an order of magnitude higher than shear thickening mechanisms. This novel slurry is demonstrated as a viable finishing media with performance similar to magnetic abrasive finishing. / Thesis / Master of Applied Science (MASc)

Friction Stir Welding (FSW) process development is very costly, and it is still experimental. A predictive model would optimize the weld by changing parameters and obtaining results that reflect the physical process. Friction is the primary adjustable parameter in FSW modeling. Currently, friction model selection is not physic-based. It is based on what is available and contributes to the best fit between the model and experimental data. The research objective is to characterize the interface tool/base material by studying the effect of tool friction coefficient and thermal properties. This is accomplished by changing welding parameters such as force, rpm, and temperature and studying the effects on dependent variables that contribute to the shear stress produced by friction. The study's findings challenge traditional friction concepts by revealing how the rapid engagement of a tool with the base material significantly reduces the impact of sliding friction. Instead, the observed friction primarily depends on the resistance of the shear layer to the tool's motion. This resistance, in turn, is chiefly influenced by the interface temperature, a factor strongly impacted by the thermal diffusivity of the tool material. Remarkably, thermal diffusivity holds the most influence (49.3%) on interface temperature. The interface of the tool material is characterized by a shear stress equation integrating pressure, RPM, thermal diffusivity, and interface temperature. Additionally, the investigation highlights the critical role of heat extraction, where materials with higher thermal diffusivity exhibit distinct outcomes: heightened torque, reduced surface temperature, minimized layer volumes, and shorter operation times.

Key Words: Thrombosis, Vascular Graft, Microfluidics, Wall Shear Stress / Vascular grafts are essential for the management of cardiovascular disease. However, the lifesaving potential of these devices is undermined by thrombosis arising from material and flow interactions on the blood contacting surface. To combat this issue, the use of antithrombogenic coatings has emerged as a promising strategy for modulating blood and graft interaction in vivo. Although an important determinant of graft performance, hemodynamics are frequently overlooked in the in vitro testing of coatings and their translatability remains poorly understood. We address this limitation with a microscale platform that incorporates vascular prosthesis and coatings with tuneable flow and surface conditions in vitro. As a proof of concept, we use the platform to test the thrombogenic performance of a novel class of lubricant infused (LIS) and antibody lubricant infused (anti-CD34 LIS) coated ePTFE vascular grafts in the presence of arterial wall shear stress, with and without the presence of endothelial cells. Our findings suggest lubricant infused coated ePTFE vascular grafts are thromboresistant under flow and may have potential for in vivo arterial grafting applications. It is moreover apparent that the microscale properties of the device could be advantageous for the testing and translation of novel antithrombogenic coatings or blood contacting prosthesis in general. / Thesis / Master of Applied Science (MASc)

Due to mechanical loading, cartilage experiences distortional change, volumetric change, and fluid flow. Research has shown cells to be responsive to unconfined compression, a load that produces all three conditions. To isolate the factor(s) responsible for chondrogenesis, the first goal of this research was to design and implement a device for the application of shear deformation to cells. Secondly, using this device, Stage 23/24 chick limb bud cells were suspended in 2% alginate and subjected to 20% shear deformation at 1 Hz. for two hours daily for three days. Gene expression, DNA content, sGAG content, and cartilage nodule formation were determined after eight days in culture and compared to results obtained for non-loaded cells. Results indicated that shear deformation at the applied level did not have a significant effect on chondrogenesis in Stage 23/24 chick limb bud cells, suggesting that this cell type is not extremely sensitive to distortional change.

Understanding the origins of the multiaxial material properties of soft tissues is crucial for quantifying the tissue material properties that govern the material behavior for acurate predictive modeling of the biological systems. Unlike many engineering structural materials, biological materials exhibit complex material behavior due to structural anisotropy and various interactions between each of the microstructrual units of the tissue. Therefore, this study aims to quantify the shear material behavior of rabbit patellar tendon under simple shear loading along the fiber direction and perpendicular to the fiber direction and to understand the role of tissue shearing and its contribution to the overall mechanical behavior of the tendon. It was hypothesized that tendon demonstrates anisotropic material response under simple shear. Results suggests that tendon exhibits direction-dependent viscoelastic shear properties, reflecting structural anisotropy. The data obtained from our present study could be used for development of constituent models using internal state variable theory.

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