Nous vous proposons un procédé de fabrication pour obtenir des dispositifs de graphène suspendu avec rendement élevé (~ 90%). Surtout, nous nous concentrons sur l'intégrabilité de procédé ainsi que sa compatibilité avec les technologies existantes de silicium. Pour répondre à ces questions, nous avons développé un système de fabrication à base de graphène qui était synthétisé par dépôt chimique en phase vapeur (CVD).L'étape la plus importante dans le processus de fabrication est liée à la gravure du substrat de SiO2 sous-jacente à suspendre les rubans de graphène. Il est souvent rapporté dans la littérature que, à ce stade, les forces capillaires peuvent provoquer l'effondrement des rubans de graphène. En dehors de cet effet, nous avons trouvé que la qualité de l'interface entre le masque de gravure et le substrat est essentielle pour suspendre les dispositifs de graphène avec succès. Ce n'est que lorsque la qualité de cette interface a été amélioré, nous avons atteint des rendements remarquablement élevés d'environ 90%. Caractérisation par spectroscopie Raman, la microscopie électronique à balayage (MEB) et microscopie à force atomique (AFM), qui était effectuée après chaque étape de fabrication, ont attesté que notre méthodologie n'a aucune dommage sur la qualité du graphène.Par la suite, nous avons utilisé la spectroscopie Raman pour étudier le dopage et la contrainte dans nos dispositifs de graphène CVD. Alors que nous avons observé une forte dopage de type p sur graphène supporté sur SiO2 dans l'air, le dopage seul ne peut pas tenir compte des spectres observés. Au lieu de cela, nous concluons que les échantillons de graphène mesurées présentent une contrainte interne de compression, qui ne se relâche pas complètement pendant la fabrication. Nous attribuons cette contrainte au budget de la température de CVD et au polymère rigide de transfert.Enfin, nous avons étudié les caractéristiques électriques de nos dispositifs à température ambiante ainsi qu'à basse température. Les mesures ont confirmé la forte dopage de type p de graphène, et en suite, ‘back-gating' ont donné une modulation faible de courant. Mesures magnéto-transport, qui sont effectuées à 20 K et 4, ont été utilisés pour extraire la densité de porteurs et la mobilité des dispositifs supportés sur SiO2. Faibles valeurs de mobilité sont attribuées à la diffusion par les joints de grains. À des champs magnétiques faibles, nous avons observé des signatures de localisation faible, ce qui implique que ‘intervalley scattering' est le mécanisme dominant dans nos échantillons. À des champs magnétiques élevés, la résistivité longitudinale a montré oscillations robuste à température qui pourraient être identifiés comme niveaux de Landau. / We propose a high-yield (~ 90%) fabrication route to obtain suspended graphene devices. Importantly, we focus on the scalability of the process as well as its compatibility with existing Si technologies. To address these issues, we developed a fabrication scheme based on graphene grown by chemical vapor deposition (CVD).The most crucial step in the fabrication process relates to the etching of the underlying SiO2 substrate to suspend the graphene ribbons. It is often reported in the literature that at this stage, capillary forces can lead to the collapse of the graphene beams. We have found that apart from this effect, the quality of the interface between the etch mask and the substrate is key to successfully suspend graphene devices. Only when the quality of this interface was improved, were we able to achieve remarkably high yields of approximately 90%. Characterization by Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM), performed after each step of fabrication, attested that our methodology does not impact the quality of the graphene.We have subsequently employed Raman spectroscopy to investigate doping and strain in our CVD graphene devices. While we did observe a strong p-type doping of graphene supported on SiO2 in air, doping alone cannot account for the observed spectra. Instead, we conclude that the measured graphene samples display a compressive internal strain, which does not fully relax during fabrication. We attribute this strain to the large temperature budget of the CVD process and to the rigid transfer polymer.

The ductility of Q&P 1180 steel was studied with regard to retained austenite transformation under different strain paths. Specimens were tested in uniaxial tension in a standard test frame as well as in situ in the scanning electron microscope (SEM). Then digital image correlation (DIC) was used to compute the effective strain at the level of the individual phases in the microstructure. Stretching experiments were also performed using limiting dome height (LDH) tooling, where specimens were strained in both biaxial and plane strain tension. The experiments were done incrementally, for each strain path, and the retained austenite at each level of strain was measured using electron backscatter diffraction (EBSD). Retained austenite levels in the uniaxial tension case dropped from an initial measured level of about 8% to about 2% during an initial strain increment of 0.02, but then stabilized as the specimen was strained to 0.1. In the plane strain and biaxial tension cases retained austenite also dropped significantly during an initial strain increment of about 0.04, but then continued to decrease as the specimens were strained to failure. Biaxial tension, in particular, was the most effective strain path for transforming retained austenite to martensite, resulting in a final volume fraction of 0.3% at an effective strain of 0.3. Retained austenite in the plane-strain tension case dropped at a faster rate than in the biaxial tension case, but finished at about 1% at a strain of 0.1. The greatest limit strains were seen in the biaxial tension case, which may be partly explained by the more effective conversion of retained austenite than was seen in the uniaxial tension case.

Using a 471-case nursing sample, the current study examined the direct and indirect relationships between workplace aggression (including physical and psychological) against nurses and their health and safety consequences. Specifically, physical and psychological aggression nurses experienced were related to their job dissatisfaction, turnover intention, physical symptoms, injuries and exposure to contagious disease directly and/or indirectly through their emotional strain (irritation, anxiety, and depression). In addition, my findings demonstrated that stronger violence prevention climate (i.e., good prevention practices/response and low pressure for unsafe practices) was related to less frequent violence and psychological aggression incidents nurses experienced. Also, my results indicated significant moderating effect of organizational violence prevention practices/response (one dimension of violence prevention climate) in the relationships of nurses' physical and psychological aggression with their anxiety and depression, such that nurses who perceived stronger (vs. weaker) violence prevention climate seemed to be more (vs. less) anxious about or depressed by aggression incidents that occurred to them. However, overall nurses who perceived stronger violence prevention climate felt less anxious and depressed at work than those who perceived weaker climate. Finally, regarding the role of social burden, there was evidence from this study supporting its positive relationship with nurses' perceived irritation, anxiety, and depression although there did not seem to be evidence supporting its moderating role between nurses' aggression experience and their emotional strain. In summary, emotional strain seemed to be a relatively consistent mediator between nurses' aggression experiences and their health or safety consequences, and nurses' perceived social context (violence prevention climate and social burden) did significantly and directly relate to their health and safety consequences, but more research is warranted before we conclude about their potential moderating role in the aggression-consequence relationships.

Bacterial resistance to non-antibiotic agents is being increasingly studied. Plasmid-mediated resistance to cationic agents, which are important biocides, has been described in antibiotic-resistant Staphylococcus aureus. Multi-resistant Staphylococcus aureus (MRSA) are often found to express resistance to a range of cationic biocides including quaternary ammonium compounds (QACs), biguanides, diamidino compounds, cationic dyes and nuclear stains. Three resistance determinants, qacA, qacB and smr genes, have been identified that confer resistance to cationic biocides in staphylococci. These genes encode multi-drug efflux pumps that remove the cationic biocides from the cytoplasm using a membrane bound pumping mechanism dependent on the cell's proton-motive force (PMF). This prevents the build up of lethal concentrations of cationic compounds within the cytoplasm avoiding cell death.This research project has focused on the S. aureus strain WBG4364, a transcipient strain carrying the cationic biocide resistant plasmid pWBG1773. The plasmid encodes resistance to several QACs, including benzalkonium chloride and CTAB, and cationic dyes rhodamine 6G, crystal violet and safranin O but not to the dye ethidium bromide and therefore differing from other cationic biocide resistant plasmids previously identified in staphylococci (Emslie et al. 1986). This unique phenotype was further classified in this study alongside those strains carrying the qac gene families, qacA/B and smr.Plasmid pWBG1773 was cloned, sequenced and analysed to reveal a unique plasmid of 2,916 bp in length. Plasmid pWBG1773 was placed with the pC194 family of rolling-circle replicating plasmids. This family appear to be largely composed of interchangeable cassette structures.The plasmid was found to carry three ORFs, designated ORF1, ORF2 and ORF3. ORF1 was homologous to rep genes of small staphylococcal ++ / plasmids belonging to the pC194 rolling-circle replication family and has been redefined as repWBG1773. ORF2 was found to have no similarity to any proteins of known function in the GenBank database whereas ORF3 was found to have homology to the marR gene, a regulator of the multiple antibiotic resistance (mar) operon of Gram-negative organisms. MIC analysis of these ORFs found both ORF2 and ORF3 were essential for expression of resistance to cationic biocides. The exact ORF2 sequence required for resistance to be expressed was reduced to only 141 nt in size. This translated to a 47 aa sequence that contained a hydrophobic C-terminus indicating ORF2 to be a membrane-bound protein. The aa sequence of ORF3 contained a helix-turn-helix motif characteristic of the DNA binding domains of MarR-like proteins. Further analysis of pWBG1773 identified a putative 'marbox', a binding site for the homologous transcriptional activators of mar, within the ORF2 sequence. This indicated that ORF3 was binding to the 'marbox' sequence and activating transcription. Induction studies have not been able to ascertain any compounds capable of interacting with the ORF3 regulatory protein resulting in induction of cationic biocide resistance. Each ORF when analysed alone had no effect on the expression of cationic biocide resistance and it is thought that a efflux pump was not involved. This is further corroborated by the CCCP efflux experiments performed in an attempt to determine the mechanism of resistance. The unique ORFs of plasmid pWBG1773 appears to encode a novel cationic biocide resistance phenotype and mechanism.MRSA strains from all around the world were analysed to determine if they possessed sequences homologous to ORF2 and ORF3. Sequences sharing a high degree of homology to ORF2 and/or ORF3 were detected in several MRSA strains including strains sensitive to all cationic ++ / biocides tested. These findings suggest that the appearance of ORF2 and ORF3 sequences in MRSAs was not an isolated event and the fact that some MRSAs do not carry both ORF2 and ORF3 sequences simultaneously indicates that these genes have another role that does not involve expression of resistance to cationic biocides.Bacteria are noteworthy for their remarkable ability to adapt to changes in their environments and possess an impressive set of tools with which to adjust the blueprint of the cell to this change. The acquisition of a single system that may decrease a potential pathogenic organisms susceptibility to a wide range of cationic biocides, such as seen in pWBG1773, poses a clinical threat, one that needs to be thoroughly investigated.

[Truncated abstract] Characterising the behaviour of calcareous sediments that possess some degree of bonding between their constituents has attracted worldwide research interest in recent years. Although many recent studies have made significant contributions in delineating the behaviour of these sediments, there is still paucity of information particularly on the cyclic behaviour of cemented calcareous soils. This thesis describes in detail the characteristic features of cemented calcareous soils and proposes methods for characterising their cyclic behaviour. Two different calcareous soils Goodwyn (GW) and Ledge Point (LP) soils representing extreme depositional environments were examined in this study. Artificially cemented sample were created using the CIPS (Calcite Insitu Precipitation Systems) technique, considering its superiority over other most commonly available cementation techniques in replicating the natural pattern of cementation, and the behaviour of natural calcarenite under monotonic loading conditions. The experimental program involved triaxial testing of both uncemented and calcite-cemented calcareous soils under different loading conditions, i.e. isotropic compression tests to high-pressure (16 MPa), monotonic shearing tests, undrained cyclic shearing tests and undrained monotonic post-cyclic shearing tests. Significant emphasis has been placed on the cyclic behaviour of these soils. Internal submersible LDVTs were used for the accurate and continuous measurement of strain down to about 10-5

The present study examined how certain characteristics of flexible work, the home environment, and the individual impact the outcomes of work-family conflict, job satisfaction, organisational commitment, and psychological strain. A questionnaire measuring perceptions of control, flexibility, job involvement, family involvement, work to family and family to work conflict, organisational commitment, job satisfaction, family support, physical boundaries, workplace isolation, psychological strain, personality, and demographic information was created and posted online. An email was circulated to 390 virtual sales employees from one large organisation in the United States inviting them to participate in the study, and 278 people responded. Results identified characteristics of the type of work, work enivronment, and the individual that are predictive of individual and organisational outcomes. Findings supported hypotheses that control, flexibility, and family support positively impact the outcomes of conflict, satisfaction, and strain for virtual workers. Job involvement was found as predicted to positively impact work to family conflict, and family involvement was positively related to family to work conflict. Contrary to predictions, a negative relationship was found between job involvement and strain, suggesting that those who identify more highly with their job also experience less strain. Consistent with earlier studies, workplace isolation was associated with reduced job satisfaction and organisational commitment (Marshall, Michaels, and Mulki, 2007). In line with boundary theory (Voydanoff, 2005), it was hypothesised that the presence of physical boundaries between work and non work domains would significantly impact measures of conflict and strain for virtual workers. However, results indicated no significant effects. A comparison of perceptions of work-family conflict between individuals with children at home and those without illustrated no significant differences between employees with children at home and those without. Speculated explanations for inconsistent findings are addressed in the discussion chapter. Work to family conflict was predicted to mediate the relationship between flexibility and job satisfaction for virtual workers, and analysis supported the presence of partial mediation. Family to work conflict was also predicted to mediate the flexibility and job satisfaction relationship, however, results were not significant in this case. Uses of workspace (i.e. for work, leisure, family activities, etc.) were tested as mediator for the relationship between family to work conflict and job satisfaction, and results did not support a mediation effect. In sum, findings of this study identify sources of both positive and negative outcomes for people working from home. Although individuals' experiences working virtually differ greatly, this study identifies common challenges and issues they face. By pinpointing the sources of conflict, satisfaction, commitment, and strain in the home office, organisations and individuals can take steps to protect workers against negative outcomes, and maximise positive outcomes. Implications and limitations of this study are discussed in the final chapter.

The introduction of high strength concrete in construction demanded an assessment of the current methods of structural design. In the case of the slabs, the benefits brought about by concretes of higher strength could translate into design of slender sections. Theoretically these sections could be prone to excessive deflections. The flexural behaviour of such structural elements should be carefully assessed. The present thesis addresses a series of particular issues such as deflection at service loads, crack formation and development of tension stiffening and ductility. An experimental program on large-scale samples was conducted. Six one way and four two way slabs made of reinforced high strength concrete were tested under simulated and accurately measured equally distributed loads. Different loading stages were recorded. Crack formation, crack patterns and yield line disposition were observed. The main characteristics of concrete that influence the deflection behaviour were assessed based on collected data and on available literature results. Statistical methods were employed in order to refine empirical equations that help in the design of slabs. To improve the calculation of deflection of slabs a new equation for the effective moment of inertia was proposed. The new formula was integrated into a method of calculating deflection and verified against experimental results. Limits of the use of high strength concrete in slabs were investigated by means of a parametric study. This was designed to answer some questions as: which would be the most important characteristics of high-strength concrete that influence the design and up to what value of strength would the beneficial effect on deflection exhaust its effectiveness. Models based on the refined empirical equations for different concrete parameters were proposed. Another area that has been studied was the ductility of high strength concrete slabs. An analytical comparative study of the ductility of slabs reinforced with steel of different ductility class was conducted. Results were critically appraised and discussed.

The study of glaciers has an immense significance for understanding and predicting global environmental change. The Earth is a dynamic system, consisting of individual units such as the cryosphere, an understanding of which may provide the basis for predicting future environmental change on a global scale. The dynamics of a glacier, a major indicator of the climatic and environmental situation is often presented as supraglacial structures, which reflect glacier formation, deformation and flow. Although structural attributes such as folds, faults, crevasse traces and foliation are commonly described in glaciers, the origin and significance of many of these structures remains unclear. This research project mapped the surface structures of Fox Glacier, using remote sensing in the form of aerial photographs and field observations, to produce a structural glaciological interpretation of the glacier surface, structural field maps of individual structures, and a schematic structural evolution of Fox Glacier. In addition, cumulative strain, and strain rates were calculated for three different areas of the lower Fox Glacier. The relationship between the observed structures and the measured strain rates has also been considered. Fox Glacier is located in the South Westland region of the South Island of New Zealand. From the Main Divide of the Southern Alps up to 3000m altitude, Fox Glacier flows for 13 km, terminating at an altitude of 270 metres in temperate rainforest, 17 km from the present coastline. The steep gradient allows for relatively rapid ice flow. Despite being a very dynamic glacier, very little research has been carried out on Fox Glacier in recent years with most research in the area being concentrated on its neighbour the Franz Josef, and even more so on the glaciers of the Eastern side of the Main Divide (e.g. the Tasman and Mueller glaciers). There is a high level of spatial variability in structural types observed, and the cumulative strain and strain rates measured on the surface of the Fox Glacier, with the variations being linked to valley topography including long-profile gradient and valley width. Strain rates of 208.78 y-1 and -162.06 y-1 were recorded on Fox Glacier. A relationship can be determined between observed glaciological structural features and measured strain rates, suggesting strain rate has an influence on the type, magnitude, location and frequency of these features, however, the study is only a ‘snap-shot’ of the strain conditions experienced in the most dynamically active time, during the summer ablation season. Developing predictive models of the structural evolution of glaciers may help further understanding of how glaciers respond to a change in climatic input, especially climatic warming. This is particularly important for larger ice sheet outlet glaciers whose structure and flow appear to reflect and control dynamics of the ice sheet behind

The principal contribution of this dissertation is a theory of Strongly Orthotropic Continuum Mechanics that is derived entirely from an assertion of geometric strain indeterminacy. Implementable into the finite element method, it can resolve widespread kinematic misrepresentations and offer unique and purportedly exact strain-induced energies by removing the assumptions of strain tensor symmetry. This continuum theory births the proposal of a new class of physical tensors described as the Intrinsic Field Tensors capable of generalising the response of most classical mechanical metrics, a number of specialised formulations and the solutions shown to be kinematically intermediate. A series of numerical examples demonstrate Euclidean objectivity, material frame-indifference, patch test satisfaction, and agreement between the subsequent Material Principal Co-rotation and P??I??C decomposition methods that produce the intermediary stress/strain fields. The encompassing theory has wide applicability owing to its fundamental divergence from conventional mechanics, it offers non-trivial outcomes when applied to even very simple problems and its use of not the Eulerian, Lagrangian but the Intrinsic Frame generates previously unreported results in strongly orthotropic continua.

Aluminium foam has a range of properties that are desirable in many applications. These properties include good stiffness and strength to weight ratios, impact energy absorption, sound damping, thermal insulation and non combustibility. Many of these characteristics are particularly attractive for core materials within sandwich structures. The combination of aluminium foam cores with thermoplastic composite skins is easily manufactured and has good potential as a multifunctional sandwich structure useful in a range of applications. This thesis has investigated the flexural behaviour of such structures using a combination of experimental and modelling techniques. The development of these structures towards commercial use requires a thorough understanding of the deformation and strain mechanisms of the structure, and this will, in turn, allow predictions of their structural behaviour in a variety of loading conditions. ¶ The experimental research involved the use of an advanced 3D optical measuring technique that produces realtime, full-field strain evolution during loading. This experimental characterisation of strain evolution in this class of sandwich structure under flexural loading is the first of its kind in the world. The experimental work studied the sandwich structure undergoing four-point bend testing. Initial studies compared the behaviour of the aluminium foam structure with a more traditional polymer foam sandwich structure. The aluminium foam structure was found to have equivalent or improved mechanical properties including more ductile deformation and an enhanced energy absorption. An investigation was conducted on the effect of core and skin thickness on the metal structure and a range of flexural behaviours were observed. Analysis of the strain distribution showed a complex development including localised effects from the non-uniform cellular structure of the material. An understanding of the variation with size is important in establishing design methods for utilising these structures. In particular, it is desirable that finite element simulations can be used to predict behaviour of these structures in a diverse range of loading conditions. This aspect was considered in the second half of this study. An existing constitutive model for aluminium foam, developed for use in compression energy absorption studies, was used to investigate finite element simulations of the flexural behaviour of the sandwich structure. The FE model was able to predict the general deformation behaviour of the thinner skinned structures although the magnitude of the load-displacement response was underestimated. It is suggested this may be related to the size effect on the input parameter characterisation. The strain distribution corresponded well with the experimental strain measurements. It was found a simple increase in the material model input parameters was able to more closely match the magnitude of the load-displacement response while maintaining the appropriate strain distribution. The general deformation shape of the model with the thicker skin corresponded reasonably well with the experimental observations. However, further work is necessary on the element failure criterion to capture the shear cracking observed. The strain distributions of the model predicted this failure with high strain concentrations matching those of the experimental contours. The last part of the thesis describes a parametric study on the effect of the foam material model input parameters on the flexural behaviour of the sandwich structure model. An important conclusion of this work is that this material model for aluminium foam can, with some development, be utilized to provide a viable method for simulating aluminium foam composite sandwich structures in flexural loading situations.