The clay mineral composition of sediments deposited in the last six oxygen isotope stages in the Gulf of Mexico continental slope was characterized. Smectite and illite were found to be the two major clay minerals of the clay fraction while kaolinite, chlorite and quartz were present in the clay fraction but in less proportions. Variations in clay mineral abundances, especially in the relative abundances of smectite and illite, were identified in relation to climate changes. Smectite was the most abundant mineral in sediments of the current (stage 1) and last interglacial maxima (stage 5) while illite dominates the clay min-eralogy of sediments from the last glacial maximum (stage 2). Relationships between clay mineralogy and physical properties were investigated as well. Significant positive correla-tions were found between Atterberg limits with the smectite content of the bulk sediment and with clay content. However, the relationship with smectite yielded a significantly higher correlation coefficient. Smectite and clay content also affect the natural water con-tent of sediments and its changes with depth.

Traitedness has been described as the “the degree to which a particular trait structure is approximated in a given person” (Tellegen, p. 28, 1991) and has been hypothesized as one explanation for findings of weak trait-behavior relationships. That is, if traits are differentially applicable to different individuals, then trait-behavior relationships may be moderated based on the strength with which an individual fits with a given trait model. This study used moderated multiple regression to test the moderating effects of four different traitedness indicators to increase the prediction of diagnostic consistency in four personality disorders, and also tested the main effects of traitedness estimates to predict cross-situational consistency of functional impairment. Traitedness estimates performed better in the prediction of increased diagnostic consistency, though there were some isolated findings of traitedness increasing crosssituational consistency of functional impairment. orientation of the clay in the nanocomposite and the simple shear process. It is found that the modulus, strength, and heat distortion temperature of the nanocomposites decrease as the clay aspect ratio and degree of orientation are reduced. The micromechanics-based models accurately describe the relationship between clay structural parameters and the corresponding moduli for exfoliated nanocomposites. The impact fracture mechanisms of polypropylene (PP)-calcium carbonate (CaCO3) nanoparticles have been investigated. A detailed investigation reveals that the CaCO3 nanoparticles act as stress concentrators to initiate massive crazes, followed by shear banding in the PP matrix.

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The field determinations of crustal electrical conductivity/depth profiles show anomalously high conductivities in the lower crust. This has yet to be explained by a consistent theory and interpretation of field results is difficult due to the lack of laboratory conductivity measurements of saturated rocks at lower crustal temperatures. A cell was designed to measure the electrical conductivity of saturated rocks up to the lower crustal conditions of; confining pressures of 1 GPa, pore-fluid pressures of 1 GPa and temperatures of 900°C. This complex exercise required the use of a metal sleeve and the use of guard-ring techniques to remove leakage currents induced by the sleeve. The development of the cell involved several years work and is a breakthrough in measurement techniques as it has enabled the measurement of saturated rock conductivities at lower crustal temperatures and high pressures for the first time. The conductivity of 14 samples of acidic and metabasic rocks was measured at a variety of confining pressures (<0.2 GPa), porefluid pressures (<0.2 GPa), temperatures (<900°C) and saturation fluids. The pressure variations showed that the basic rocks had a conductivity too high to be explained by conduction through saturating electrolyte alone. The temperature variation showed a dramatic difference between acidic and basic rocks. The acidic rocks showed large decreases in conductivity above 350°C after initial rapid increases in conductivity. The basic rocks showed no such reduction in conductivity indicating that a conduction mechanism in addition to pore-fluid conduction was present. Results indicate that saturated -rocks at high temperatures have 7/ conductivities sufficient to explain the high conductivity layers in the upper lower crust whereas acidic rocks do not. The results also demonstrate that graphite may be an important additional conduction mechanism possibly accounting for the moderately high conductivities in the lower lower crust even in the absence of electrolyte conduction

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Dentistry / Master / Master of Dental Surgery

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

Nanofluids are two-phase mixtures of base fluids and nanoparticles. They possess unique thermal, magnetic, electronic, optical and wetting properties, and thus have tremendous applications in many fields. For practical applications of nanofluids in heat-transfer systems, we often try to achieve a global aim such as optimization of system highest temperature and optimization of system overall thermal resistance. To improve energy efficiency, attention should focus on designing nanofluids for the best global performance. As indicated by constructal theory, flow structures emerge from the evolutionary tendency to generate faster flow access in time and easier flow access in configurations that are free to morph. Constructal theory can not only predict natural flow architectures but also guide design of flow systems. In this thesis, constructal design is applied to study nanofluid heat conduction such that the system (global) performance can be constantly improved. An examination of the variation of preferred heat-transfer modes for different matter states concludes that the preferred heat-transfer modes for solid, liquid and gas are conduction, convection and radiation, respectively. After an analogy analysis of plasma heat conduction and nanofluid heat conduction, it is proposed that forming continuous particle structures inside base fluids may enhance the heat conduction in nanofluids. Staring from the conventional nanofluids with particles dispersed in base fluids (dispersed configuration of nanofluids), we first perform a constructal design of particle volume fraction distribution of four types of nanofluids used for heat conduction in eight systems. The constructal volume fraction distributions are obtained to minimize system overall temperature differences and overall thermal resistances. The constructal overall thermal resistance is found to be an overall property fixed only by the system global geometry and the average thermal conductivity of nanofluids. The constructal nanofluids that maximize the system performance under dispersed configuration are the ones with higher particle volume fraction in region of higher heat flux density. Based on the proposal of forming continuous particle structures inside base fluids, blade configurations of nanofluids are analyzed analytically and numerically for both heat-transferring systems and heat-insulating systems. Comparisons are made with dispersed configurations of nanofluids with constructal particle volume fraction distributions or thermal conductivities of upper or lower bounds. The superiority of blade configuration is always very obvious even with rather simple particle structures. As the blade structures are more sophisticatedly designed, system performance of blade configuration will become even better. To improve the particle structure design, efforts are put on optimizing crosssectional shape of particle blade to achieve better system performance. The triangular-prism-shaped blade is shown to perform the best. Since heat conduction and fluid flow inside trees follow the same linear transport mechanism, the prevalent leaf structures in nature are expected to provide some guidelines for the design of blade-configured heat-conduction system. Analytical and numerical studies are thus done on the quasi-rhombus-shaped and quasi-sector-shaped systems up to the one branching level. More sophisticated blade shapes are verified to lead to better system performance. The advantage of quasi-rhombusshaped system compared to quasi-sector-shaped system is also shown. / published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

Intermediate filaments, microtubules and microfilaments are the major components of the cytoskeleton. Though it is known that intermediate filaments play an important role in the mechanical behaviour of cells, it is surprising that their mechanical properties are far from being fully understood. The morphology and assembly process of the vimentin intermediate filaments (IFs) were studied using transmission electron microscopy (TEM) and atomic force spectroscopy (AFM). The width of the vimentin was found to change as the assembly proceeded. This finding agrees with the literature about the compaction process of vimentin IFs. The width of the IFs decreased gradually, while the range of width increased within the first few minutes after assembly initiation, and then decreased at last and became stable at 12.80±2.20nm. The average length of the IFs increased with decreasing rate. The length attained 485.60±162.23nm at 120 minutes. The range of length increased which revealed the assembly process was randomly occurring between filaments in the solution. The height of the IFs obtained with AFM did not show the periodicity in contrary to the literature. It may be due to the flattening of IFs on the functionalized mica(AP-mica) surface, or the periodicity was not prominent to be observed morphologically. In the force spectroscopy study, the nanomechanical properties of individual vimentin intermediate filaments were studied using AFM. Fresh vimentin intermediate filaments and samples fixed with glutaraldehydewere examined, and force-displacement curves with nano-scale resolutions of different vimentin intermediate filament samples were analysed. The use of glutaraldehydefixative provided cross-linking of the IF, and the structural change will result in differences in their force-displacement curves which helped to provide comparison with the non-fixed samples in order to identify the structure-mechanical property relationship. Statistical studies of these curves revealed that tearing off of protofilaments from the mature intermediate filaments (with and without glutaraldehyde) occurred inthe low force regime below 100pN, and successive tearing off events were observed readily below 25 nm separations, which were comparable with the lengths of domains of around 20 nm. Different features of sawtooth indicated the possibility of sliding mechanism in vimentin IF, and the sliding was found to occur at 30.44±13.41pN. Helical domain unfoldings were observed only in the non-fixed samples to start at 10.19±5.63pN on average witha mean increase of 42.12±26.74nm. This force agreed with the prediction of the extended Bell model described in the literature and the length increase was around double of the domain length, which indicated the uncoiling of the coiled-coils. The force-displacement curves also reveal different modes of failure of the vimentin intermediate filaments including protofilaments slippage/sliding and entropic elasticity. A new tearing off model was hence proposed based on different modes of failure and a previous model developed for desmin filaments reported in literature. / published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

Since the discovery of superconductivity in Sr2RuO4, there has been intense research interest and efforts on its unconventional pairing symmetry. Although its normal state can be qualitatively described as a quasi-two-dimensional Fermi liquid, surprisingly, Sr2RuO4 turns out to be the prime candidate of the chiral p + ip superconductor, analogous to 3He-A. Such a state is of great interest surrounding, since under a certain conditions it hosts such exotic objects as half-quantum vortices and Majorana bound states, one possible route to an enigmatic quantum computer. Nevertheless, although it is well established now that this superconducting state has odd-parity, and most likely breaks time-reversal symmetry, the negative result on the search of edge current is one of the critical challenges to its chiral p-wave order. These serious discrepancies have even triggered a debate on the primary source of its superconductivity. Motivated by this debate, in this thesis we propose two independent methods to resolve this controversy via “smoking-gun" experiments. First, the vortex structure within the single-band and two-band models is studied within a mean-field theory. The pattern of the local density-of-state at zero bias shows significant anisotropy in the two-band model, while it is nearly isotropic in the single-band case. Also, the spin lattice relaxation rate at the vortex site is greatly enhanced in the single-band case but not in the two-band scenario. These important distinctions stem from the topology of different Fermi surfaces, and can be tested by using standard probes such as scanning tunneling microscope and nuclear magnetic resonance. In the second proposal, we focus on the two-band scenario, and apply a renormalization group theory to explain the form of spin density wave fluctuations. This theory not only reconciles the absence of long range spin density wave order with strongly enhanced fluctuations, but also unveils the mutual exclusion of these fluctuations and p-wave superconducting pairing. Such an exclusion is reflected in the suppression of the spin-spin correlation function at low energies, which can be measured in the inelastic neutron scattering experiment. This suppression, if not observed experimentally, would be a critical challenge to the two-band model, and an indirect but strong support to the assignment of the single γ-band as the primary source of the unconventional pairing. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy