This thesis discusses the chemistry and physics of Cu and H2O on ZnO surfaces, based primarily on results from quantum chemical calculations. The underlying context is heterogeneous catalysis, where Cu/ZnO-mixtures are used in the industrial synthesis of methanol and in the water gas shift reaction. Electron transfer between small Cu clusters and ZnO is central to this thesis, as are the design and use of models that can describe realistic and very large-scale ZnO surface structures while still retaining the electronic nature of the system. Method and model enhancements as well as tests and validations constitute a large part of this thesis. The thesis demonstrates that the charges of small Cu clusters, adsorbed on the non-polar ZnO(10-10) surface, depend on whether the Cu clusters contain an even or odd number of atoms, and whether water is present (water can induce electron transfer from Cu to ZnO). On the polar Zn-terminated ZnO(0001) surface, Cu becomes negatively charged, which causes it to attract positively charged subsurface defects and to wet the ZnO(0001) surface at elevated temperatures. When a Cu cluster on a ZnO surface becomes positively charged, this happens because it donates an electron to the ZnO conduction band. Hence, it is necessary to use a method which describes the ZnO band gap correctly, and we show that a hybrid density functional, which includes a fraction of Hartree-Fock exchange, fulfills this requirement. When the ZnO conduction band becomes populated by electrons from Cu, band-filling occurs, which affects the adsorption energy. The band-filling correction is presented as a means to extrapolate the calculated adsorption energy under periodic boundary conditions to the zero coverage (isolated adsorbate, infinite supercell) limit. A part of this thesis concerns the parameterization of the computationally very efficient SCC-DFTB method (density functional based tight binding with self-consistent charges), in a multi-scale modeling approach. Our findings suggest that the SCC-DFTB method satisfactorily describes the interaction between ZnO surfaces and water, as well as the stabilities of different surface reconstructions (such as triangularly and hexagonally shaped pits) at the polar ZnO(0001) and ZnO(000-1) surfaces.

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High density polyethylene (HDPE) is a widely used plastic but it is also a combustible material. One way of reducing flammability is to add fillers, such as magnesium hydroxide (Mg(OH)2). However, this has a deleterious effect on the mechanical properties of composites. It has been found that one possible method of restoring mechanical properties is to modifY the filler particles with coating agents, such as stearic acid. In the present work, this idea was taken a stage further with the use of various metal stearates (e.g. magnesium stearate, calcium stearate, and zinc stearate) for modifying filler. The fillers examined were magnesium hydroxide and calcium carbonate. A filler loading of 40% w/w was used in all samples. Samples were moulded into a variety of shapes for mechanical testing. Such tests included, tensile, flexural, and impact testing. To obtain deeper understanding of the effect of the coating agents on the fillers, a variety of fundamental tests were carried out. These included Diffuse Reflectance FTIR (DRIFT), Thermal Analysis using a DSC cell, Xray Diffraction (XRD), contact angle measurement. Unfilled HDPE, uncoated filled-HDPE, and coated filled-HDPE were compared using uncoated filled-HDPE as a base line. Uncoated filled-HDPE is more brittle than unfilled HPDE. Surface modification of filler improves the toughness properties. Comparing coated filled-compounds, stearic acid and zinc stearate caused a small improvement, magnesium stearate improved the properties significantly with calcium carbonate while calcium stearate gave the best results for coating magnesium hydroxide. One monolayer coating gave the best compound properties compared to other degrees of coating. Although, tensile/flexural strength was not greatly affected elongation at yield, extension at maximum load, and impact properties increased significantly. DSC was used to observe the disappearance and conversion of coating agents as coating proceeded. X-ray diffraction showed the effect of injection moulding on the orientation of the filler and polymer. During coating of the filler particles, XRD and DSC were used to follow incorporation of stearate particles to produce the monolayer coverage. Surface free energy results showed that surface modification of filler resulted in the reduction of hydrophilicity of filler leading to tougher composites compared with uncoated filled-compounds.

Marketplace volatility in the pork industry demands that producers re-evaluate production practices in order to remain profitable. Stocking density and dietary energy concentration independently affect performance and economic returns of growing finishing pigs. However, there is limited information on whether the interaction between these two factors is important for optimizing productivity and maximizing economic returns. The objective of this study was to determine if the dietary energy concentration that maximizes performance and economic returns varies with stocking density. Treatments were arranged as a 2 × 3 × 3 factorial included; sex (barrows and gilts), dietary energy (2.15, 2.30 and 2.45 Mcal NE/kg) and stocking density (14, 17 or 20 pigs per pen providing 0.92, 0.76 and 0.65 m2 per pig, respectively). A total of 932 pigs were used with three replications of 18 treatments. Pigs were randomly assigned to pens within sex to achieve an average initial BW of 75 kg. Wheat and barley based diets were formulated to meet or exceed the pigs’ nutrient requirements (National Research Council, 2012) and were fed in three phases within sex at each energy concentration. Overall (75 to 118 kg BW), as dietary energy increased from 2.15 to 2.45 Mcal NE/kg, ADG increased from 1.17 to 1.23 kg/d, ADFI decreased from 4.09 to 3.77 kg/d, G:F improved from 0.29 to 0.33 and caloric intake increased from 8.81 to 9.29 Mcal NE/d (P < 0.05). When stocking density was increased from 14 to 20 pigs per pen, ADG (1.21 to 1.17 kg/d), ADFI (4.00 to 3.82 kg/d) and caloric intake (9.19 to 8.12 Mcal NE/d) decreased (P < 0.05). Neither dietary energy concentration nor stocking density had a significant effect on the utilization of calories for growth (Gain:Mcal). Feeder visits per pig and time at the feeder per pig were decreased when stocking density increased from 14 to 20 pigs per pen (P < 0.01). Total time at the feeder and time at the feeder per pig were increased when dietary energy decreased from 2.45 to 2.15 Mcal of NE/kg. Per pen, aggressive incidents at the feeder increased (P < 0.05) and there was a tendency for increased aggressive incidents per pig (P = 0.09) when stocking density was increased. There was a linear increase (P < 0.01) in income over feed cost (IOFC) with increased stocking density, and there was a tendency (P = 0.08) for a linear increase in IOFC when dietary energy was increased. The dietary energy which maximized the IOFC did not vary with stocking density. Dietary energy and stocking density independently affect pig performance, behavior, and economic returns and the optimal dietary energy does not depend on stocking density (dietary energy by stocking density interaction).

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Recent studies have demonstrated that an acute, low dose of ketamine, a non-competitive NMDA receptor antagonist, provides rapid and sustained antidepressant effects in patients with major depressive disorder. Studies in rodents have shown that the antidepressant properties of ketamine are due to an increase in dendritic spine density in the cortex. Our goal was to determine whether these effects are specific to ketamine and whether they are dependent on dose, drug regimen and brain region. We observed that the effects of ketamine on spine density were dependent on dose and drug regimen and were also brain region specific. In addition, MK-801, another NMDA receptor antagonist, did not demonstrate the same effects on spine density as ketamine. Furthermore, genetic NMDA receptor hypofunction significantly reduced spine density. Our studies demonstrate that while acute ketamine treatment leads to an increase in cortical spine density, chronic administration has opposite and potentially detrimental effects.

Recent studies have demonstrated that an acute, low dose of ketamine, a non-competitive NMDA receptor antagonist, provides rapid and sustained antidepressant effects in patients with major depressive disorder. Studies in rodents have shown that the antidepressant properties of ketamine are due to an increase in dendritic spine density in the cortex. Our goal was to determine whether these effects are specific to ketamine and whether they are dependent on dose, drug regimen and brain region. We observed that the effects of ketamine on spine density were dependent on dose and drug regimen and were also brain region specific. In addition, MK-801, another NMDA receptor antagonist, did not demonstrate the same effects on spine density as ketamine. Furthermore, genetic NMDA receptor hypofunction significantly reduced spine density. Our studies demonstrate that while acute ketamine treatment leads to an increase in cortical spine density, chronic administration has opposite and potentially detrimental effects.

This thesis begins with a review on the topic of molecular electronics. The purpose of this review is to motivate the need for good theory to understand and predict molecular electronics behaviour. At present the most promising theoretical formalism for dealing with this problem is a combination of density functional theory and nonequilibrium Green's functions (NEGF-DFT). This formalism is especially attractive because it is an ab-initio technique, meaning that it is completely from first principles and does not require any empirical parameters. An implementation of this formalism has been developed by the research group of Hong Guo and is presented and explained here. A few other implementations which are similar but differ in some ways are also discussed briefly to highlight their various advantages and disadvantages. / One of the difficulties of ab-initio calculations is that they can be extremely costly in terms of the computing time and memory that they require. For this reason, in addition to using appropriate approximations, sophisticated numerical analysis tech niques need to be used. One of the bottlenecks in the NEGF-DFT method is solving the Poisson equation on a large real space grid. For studying systems incorporating a gate voltage it is required to be able to solve this problem with nonperiodic boundary conditions. In order to do this a technique called multigrid is used. This thesis examines the multigrid technique and develops an efficient implementation for the purpose of use in the NEGF-DFT formalism. For large systems, where it is necessary to use especially large real space grids, it is desirable to run simulations on parallel computing clusters to handle the memory requirements and make the code run faster. For this reason a parallel implementation of multigrid is developed and tested for performance. The multigrid tool is incorporated into the NEGF-DFT formalism and tested to ensure that it is properly implemented. A few calculations are made on a benzenedithiol system with gold leads to show the effect of an applied gate voltage.

Modeling spatial variables involves uncertainty. Uncertainty is affected by the degree to which a spatial variable has been sampled: decreased spacing between samples leads to decreased uncertainty. The reduction in uncertainty due to increased sampling is dependent on the properties of the variable being modeled. A densely sampled erratic variable may have a level of uncertainty similar to a sparsely sampled continuous variable. A simulation based approach is developed to quantify the relationship between uncertainty and data spacing. Reference realizations are simulated and sampled at different spacings. The samples are used to condition additional realizations from which uncertainty is quantified. A number of factors complicate the relationship between uncertainty and data spacing including the proportional effect, nonstationary variogram, classification threshold, number of realizations, data quality and modeling scale. A case study of the relationship between uncertainty and data density for bitumen thickness data from northern Alberta is presented. / Mining Engineering

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