Thesis (M.S.)--University of Michigan, 1980.

Thesis (Ph. D.)--Oregon State University, 2005. / Printout. Includes map in pocket. Includes bibliographical references. Also available on the World Wide Web.

Techn. Universiẗat, Diss., 2005--Darmstadt.

Porous media affect hydrate stability by forcing hydrate-liquid interfaces to form high curvature geometries and by forcing the molecules of the hydrate, liquid, and sedimentary particles that compose the medium to interact where they are in close proximity. To evaluate these effects we first create synthetic spherical packings to approximate pore space geometry. We use the synthetic pore space to calculate the perturbation to the chemical potential caused by the geometrical constraints. Our model predictions agree with published data for ice-water and water-vapor systems. When particles are well-approximated as spheres, our model fits the data with R-squared values that range between about 80% to over 99%. However, our model needs to be improved for porous media that contain a significant fraction of non-equant particles such as clay. Lastly, we demonstrate how our model can be used in predictions for the evolution of hydrate saturation. This thesis includes unpublished co-authored material.

The Kribi-Campo sub-basin is the northernmost of a series of Aptian basins along the coast of West Africa. These extensional basins developed as a result of the northward progressive rifting of South America from West Africa, initiated c. 130 Ma ago. Post-rift sediments of the Kribi-Campo sub -basin contain several regional unconformities and changes in basin-fill architecture that record regional tectonic events. The tectono-stratigraphic evolution and plumbing system has been investigated using a high-quality 3D seismic reflection dataset acquired to image the deep-water Cretaceous-to-Present-day post-rift sediments. The study area is located c. 40 km offshore Cameroon in 600 to 2000 m present-day water depth, with full 3D seismic coverage of 1500 km2, extending down to 6.5 seconds Two-Way Travel time. In the late Cretaceous the basin developed as a result of tectonism related to movement of the Kribi Fracture Zone (KFZ), which reactivated in the late Albian and early Senonian. This led to inversion of the early syn-rift section overlying the KFZ to the southeast. Two main fault-sets - N30 and N120 - developed in the center and south of the basin. These normal faults propagated from the syn-rift sequences: the N120 faults die out in the early post-rift sequence (Albian time) whilst N30 faults tend to be associated with the development of a number of fault-related folds in the late Cretaceous post-rift sequence, and have a significant control on later deposition. The basin is filled by Upper Cretaceous to Recent sediments that onlap the margin. Seismic facies analysis and correlation to analogue sections suggest the fill is predominantly fine-grained sediments. The interval also contains discrete large scale channels and fans whose location and geometry were controlled by the KFZ and fault-related folds. These are interpreted to contain coarser clastics. Subsequently, during the Cenozoic, the basin experienced several tectonic events caused by reactivation of the KFZ. During the Cenozoic, deposition was characterized by Mass Transport Complexes (MTCs), polygonal faulting, channels, fans and fan-lobes, and aggradational gullies. The main sediment feeder systems were, at various times, from the east, southeast and northeast. The plumbing system shows the effects of an interplay of stratigraphic and structural elements that control fluid flow in the subsurface. Evidence for effective fluid migration includes the occurrence of widespread gas-hydrate-related Bottom Simulating Reflections (BSRs) 104 - 250 m below the seabed (covering an area of c. 350 km2, in water depths of 940 m - 1750 m), pipes and pockmarks. Focused fluid flow pathways have been mapped and observed to root from two fan-lobe systems in the Mid-Miocene and Pliocene stratigraphic intervals. They terminate near, or on, the modern seafloor. It is interpreted that overpressure occurred following hydrocarbon generation, either sourced from biogenic degradation of shallow organic rich mudstone, or from effective migration from a thermally mature source rock at depth. This latter supports the possibility also of hydrocarbon charged reservoirs at depth. Theoretical thermal and pressure conditions for gas hydrate stability provide an opportunity to estimate the shallow geothermal gradient. Variations in the BSR indicate an active plumbing system and local thermal gradient anomalies are detected within gullies and along vertically stacked channels or pipes. The shallow subsurface thermal gradient is calculated to be 0.052 oC m-1. With future drilling planned in the basin, this study also documents potential drilling hazards in the form of shallow gas and possible remobilised sands linked with interconnected and steeply dipping sand bodies.

Magister Pharmaceuticae - MPharm / Many active pharmaceutical ingredients (APIs) have poor physicochemical properties such as solubility, dissolution and chemical stability. Several strategies are used to enhance and improve these properties of the API. Co-crystallization and polymorphism studies are possible strategy used in pre-formulation studies to optimize these properties of the drug without modifying its pharmacological effect. The purpose of this research was to investigate the polymorphism and co-crystallization effects of the penicillin-type antibiotic, amoxicillin tri-hydrate. Several techniques such as: slow evaporation, slow cooling, vapour diffusion, sublimation, grinding and solvent assisted grinding was employed. In producing co-crystals, the API was non-covalently bound to selected co-formers such as: saccharin, nicotinamide, salicylic acid, L-tartaric acid, D-tartaric acid, L-aspartic acid, stearic acid, benzoic anhydride, oxalic acid di-hydrate, cinnamic acid, succinic acid and citric acid monohydrate. Nine co-crystals of amoxicillin tri-hydrate had been formed. Differential scanning calorimetry (DSC), hot stage microscopy (HSM) and thermal gravimetric analysis (TGA) was conducted to analyse the thermal behaviour of the co-crystals. Powder X-ray diffraction (PXRD) and spectroscopic techniques [infra-red (FTIR) and H1-nuclear magnetic resonance (H1MNR)] were employed for screening of the co-crystal forms. Furthermore, dissolution testing was conducted to investigate the application of the newly derivatised forms.

The nature of the calcium-silicate-hydrate phase in hydrated Portland cement has been the subject of considerable debate for decades. Various nanostructural models have been proposed including those constructed from colloidal-based particulate systems and those formulated on the basis of layered calcium-silicate-hydrates. These are examined in detail in the literature review section of the thesis. Relatively recent composition-based models have been proposed by Taylor and Richardson-Groves. These models contain structural elements comprised of 1.4 nm tobermorite and jennite. Details are also provided in the literature review. There is however a paucity of data on the engineering properties of pure calcium-silicate-hydrate phases and virtually none on the mechanical performance of 1.4 nm tobermorite and jennite. The global objective of this thesis was to examine the compatibility of the composition-based models with the engineering behaviour of the pure tobermorite and jennite phases. Pure phases of a variety of layered calcium-silicate-hydrates were synthesized and novel techniques developed to determine their engineering characteristics in a variety of test environments. The silicate phases investigated included high temperature silicates e.g. gyrolite as these layered structures are known to be cross-linked. Investigation of the role of ‘structural’ water in layered silicates was also a part of these studies. The thesis is based on a series of twelve refereed journal papers by the candidate (eight are published or accepted and four have been submitted for publication). The research is reported in four parts with each part comprised of three papers. Each part provides insight into the nanostructure of C-S-H in hydrated cement. The arguments developed evolve from an assessment of various factors including aging and the state of water in the layered silicates. The first part of the thesis focuses on the development and application of dynamic mechanical thermo-analysis methods that are sensitive to phase changes and are useful for assessing the compatibility of engineering behaviour with model composition based on 1.4 nm tobermorite and jennite. The second part represents a study of volume stability and mechanical property-porosity relationships for the pure silicate phases that are germane to these studies. The third part focuses on prolonged aging and role of structural water in cement paste hydrated for 45 years. The fourth and final part attempts to address the role of layer structure e.g. cross-linking of silicate sheets on engineering behaviour. The non-uniqueness of modulus of elasticity with respect to equilibrium moisture content is demonstrated. Structurally related irreversible effects that are dependent on drying history are rationalized. A summary chapter is provided wherein the evidence for a composition-based model with tobermorite and jennite structural units is rationalized in terms of the experimental evidence provided in this study and suggestions for future research are discussed.

The water molecules in inorganic hydrate salts adopt different geometries and are involved in different hydrogen bond interactions. In this work, magic-angle spinning (MAS) and static 17O solid-state NMR experiments are performed to characterize the 17O electric field gradient (EFG) and chemical shift (CS) tensors of the water molecules in a series of inorganic salt hydrates which include: oxalic acid hydrate, barium chlorate hydrate, sodium perchlorate hydrate, lithium sulphate hydrate, and potassium oxalate hydrate, which were all enriched with 17O water. Data were acquired at magnetic field strengths of 9.4, 11.75, and 21.1 T. Gauge-including projector-augmented-wave density functional theory (GIPAW DFT) calculations are performed on barium chlorate hydrate and oxalic acid hydrate where structural changes including the Ow-H•••O distance, H-O-H angle, and O-H distance are employed to understand their impact on the NMR parameters. Furthermore, simplified molecular models consisting of a metal cation and a water molecule were built to establish the effect the M-Ow distance has on the parameters. The computational studies are then used to understand the experimental results. The 17O quadrupolar coupling constant ranged from 6.75 MHz in K2C2O4•H2O to 7.39 MHz in NaClO4•H2O while the asymmetry parameter ranged from 0.75 in NaClO4•H2O to 1.0 in K2C2O4•H2O and the isotropic chemical shift ranged from -15.0 ppm in NaClO4•H2O to 19.6 ppm in BaClO3•H2O. The computational results revealed the trends for each parameter, where there is an increasing trend for quadrupolar coupling constant and span as a function of increasing hydrogen bond distance, decreasing trend for the three chemical shift tensors as a function of increasing M-Ow distance and unclear trends for asymmetry parameter and skew due to competing electronic factors. Overall, this study provides benchmark 17O NMR data for water molecules in crystalline hydrates, including the first measurement of 17O chemical shift anisotropy for such materials.

This study has consisted primarily of the addition of varying amounts of chloral hydrate to nutrient agar plates and the determination of the definite effects thereof upon the colony plate counts of various samples of milk.

This thesis deals with storage of natural gas in hydrates, forming of hydrate, its transportation and storage. Within the calculation part, three hydrate forming reactors are compared. According to the paramters used in the calculations, a reactor is designed. Basic drawing documentation is also available. The final calculations focus on the nominal evaporation of the storage tank.