Thesis (M.Ch.E.)--University of Delaware, 2006. / Principal faculty advisor: Norman J. Wagner, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 69-73). Also available in electronic version.

The mechanical properties of PET (widely used in bottles and synthetic fibres) and Nylon 11 (also used in the fabrication of synthetic fibres) were studied over several decades of strain rate at different temperatures in an effort to provide a more complete description of these materials behaviour. Processing techniques can be improved if such information is available. Tests were carried out using a conventional Hounsfield machine and two in-house-developed dropweight and a cross bow systems from 10°C to 200°C. The three systems enable true stress vs. true strain curves to be calculated.

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17β-Estradiol (E2) and progesterone (P4) have various important functions but the effect of these endogenous hormone concentrations on fibrin network formation has not been established. It is essential to understand natural hormone mechanisms since these hormones are still present in circulation while hormonal contraceptives, which are associated with increased risk of venous thromboembolism, are used. In this study the formation of a fibrin network is analysed when different physiological concentrations of E2 and P4 is added to platelet poor plasma. Blood coagulation is critical for haemostasis but when the formation of a stable clot is influenced in such a way that hypercoagulation takes its course, it can have detrimental effects as it increases the risk of venous thrombosis. During blood coagulation fibrinogen is converted into fibrin in the presence of thrombin. The formation of a dense fibrin clot structure is quite an intense process and packaged in very specific ways. Both E2 and P4 has the ability to shift the haemostatic balance to a hypercoagulable state and therefore viscoelastic studies, morphological analysis as well as turbidimetry were used in this study to observe the possible changes in the fibrin network formation. Viscoelastic studies included thromboelastography (TEG) which gave insight to the properties of clot formation. Morphological studies included scanning electron microscopy (SEM) and atomic force microscopy (AFM) which delivered an investigation in fibrin network morphology, fibrin fiber diameter and surface roughness. Turbidimetry included further analysis of plasma fibrin clot formation and clot lysis time (CLT). Results showed that E2 and P4 showed hypercoagulable viscoelastic properties with decreased fibrin diameter and surface roughness while increased occurrence of dense matted deposits (DMDs) were evident. Turbidimetry showed decreased CLT for E2, but not P4. These results suggest in the presence of endogenous estrogen and progesterone, which is associated with hypercoagulability, the additional burden of synthetic hormones may result in a prothrombotic and hypercoagulable state in females with an inflammatory predisposition. It appears that both E2 and P4, which are known for their anti- and pro-inflammatory action, may influence fibrin network formation on a molecular level. These results are of clinical importance when considering hormones as either a pathological agent or therapeutic intervention. / Dissertation (MSc)--University of Pretoria, 2016. / Physiology / MSc / Unrestricted

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1979. / Vita. / Includes bibliographical references. / by Kenji Yasuda. / Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1979.

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