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<p>The objectives of this study were to create an in vitro situation which closest resembled the clinical situation by inclusion of human dentine discs at a specified anatomic location as barrier and evaluating if comparable or graded perfusion could be identified as well as whether a link existed between dentine thickness and permeability. The other leg of the study was to evaluate the cytotoxicity of Xeno III, one of the newly released new generation dentine bonding agents and to evaluate its cytotoxicity in an in vitro pulp chamber device, determining which thickness of dentine would be able to protect the dental pulp from noxious substances in the bonding agent.</p>

<p>The aim of this project was to compare the shear bond strengths of three light cure orthodontic adhesive resins with three different stainless steel molar brackets.</p>

Submitted in fulfilment of the degree of Doctor of Dental Material Science in the Department of Dental Services, Faculty of Health Sciences, Durban University of Technology, Durban, South Africa, 2008. / Introduction: Incorporating a feldspar chemical bond between alumina filler particles is expected to increase the wear resistant and flexural strength properties, while reducing flexibility of dental composites. Aims and Objectives: An investigation was carried out to evaluate the influence of the feldspar chemical bonding between alumina filler particles on wear, flexural strength and flexibility of experimental alumina/feldspar dental composites. It was hypothesized that wear resistance and flexural strength would be significantly increased with increased feldspar mass, while flexibility was expected to decrease. Methods: Alumina was chemically sintered and bonded with 30%, 40%, 50% and 60% feldspar mass, silanized and infiltrated with UDMA resin to prepare the dental restorative composite material specimens. Results and conclusions: Significantly higher wear resistant characteristics resulted with increased feldspar mass (p<0.5). Improvements in flexural strength characteristics as the feldspar mass was increased was not statistically different (p>0.5). Flexibility characteristics as the feldspar mass was increased was not statistically different (p>0.5). The alumina/feldspar specimens showed lower flexibility (mm displacement) than SR ADORO (p<0.05). Feldspar chemical bonding between the alumina particles may improve on the wear resistance and Flexibility of alumina/feldspar composites when compared to SR ADORO. This study evaluated the influence of a chemical feldspar bond between alumina filler particles.

An experimental investigation to study the influence of base metal composition on the time required to achieve complete isothermal solidification (tf) during TLP bonding of three Ni-base superalloys was performed. Alloys IN 738, DS Rene80 and DS IC 6 show similar behaviour when bonded at 1100 oC, with comparable tf. However, at higher temperatures, IN 738 requires extended period of time (as compared to DS Rene80 and DS IC 6) to achieve complete isothermal solidification. The prolonged tf in IN 738 appears to be caused by a more pronounced reduction in concentration gradient of the diffusing solute within the material during bonding. In contrast, the shorter complete isothermal solidification time experienced by alloy DS IC6 is attributable to its capability to better accommodate the diffusing solute, through the formation of densely packed second-phase precipitates in the diffusion affected zone (DAZ).

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Introduction: Deliberate self-harm is being increasingly recognised as a behaviour with significant clinical importance. Yet, there remains uncertainty regarding which forms of psychological therapy are most effective for its treatment. Schema Therapy is an integrative psychotherapy blending elements of cognitive behaviour therapy, object relations and gestalt therapy into a unified approach for the treatment of individuals with complex and chronic psychological conditions. The current thesis aimed to provide a better understanding of the Schema Therapy model and its association with deliberate self-harm. Systematic Review: Despite the increasing evidence base for the efficacy of Schema Therapy, less is known about the evidence for its theoretical underpinnings. To address this gap in the literature a systematic review was undertaken to explore the following question: How empirically supported is the theoretical underpinning of Schema Therapy? In a systematic search of the literature conducted until 01 June 2012, studies based on cross-sectional, longitudinal, intervention, meditational and experimental designs were considered. These studies underwent detailed quality analysis culminating in 19 articles being included in the current review. Overall these studies indicate that many of the key theoretical assumptions in Schema Therapy are supported by the literature. Empirical Study: Schema Therapy has recently been expanded to include the ‘schema mode’ concept, with a number of researchers highlighting an association between particular schema modes and a number of chronic psychological conditions. Although the schema mode model allows a method for understanding moment-to-moment emotional states it has not previously been explored in relation to deliberate self-harm. The current project aimed to explore the relationship between these variables and their association with early experiences of parental bonding and current levels of perceived stress. 70 psychiatric outpatients with a history of deliberate self-harm completed a number of measures including the Deliberate Self-Harm Inventory, Schema Mode Inventory, Parental Bonding Instrument and Perceived Stress Scale. Results revealed significant associations between deliberate self-harm, maladaptive schema modes, perceived stress and patterns of parental care. Maladaptive schema modes significantly mediated the relationship between parental care and deliberate self-harm. The Punitive Parent and Angry Child modes were significant mediators in this relationship. Conclusion: Results from the systematic review support the notion that Schema Therapy has a good theoretical underpinning. The empirical study also supports Schema Therapy by highlighting the meditational role of maladaptive schema modes in the relationship between low parental care in childhood and deliberate self-harm in adulthood. These findings provide further support for the Schema Therapy model and suggest that individuals with deliberate self-harm may benefit from this treatment.

When multiple hydrogen bonds lie in-plane and parallel to each other in close proximity, they experience additional positive or negative secondary electrostatic interactions. When a pair of molecules are arranged such that every hydrogen bond acceptor is on one molecule and every hydrogen bond donor is on another, the positive secondary electrostatic interactions are maximised, and thus the association constant of the complex is enhanced. This thesis will present the development of a family of quadruple hydrogen bonded complexes containing only positive secondary interactions, which confers unprecedented stability. The complexes are sufficiently stable to maintain strong binding in polar solvents such as acetonitrile and can be switched “on” and “off” with acid and base. They will be developed into synthons for acid-base responsive supramolecular recognition, for use in stimuli-responsive supramolecular polymers and gelators.