A model has been developed which simulates a system consisting of a horizontal and vertical ground-coupled heat exchanger connected in parallel to the same heat pump. The model was used in computer simulations to investigate how the annual minimum and mean fluid temperatures at the heat pump varied as several parameters of the combined system were changed. A comparison was also made between different control settings for fluid flow rate distribution between the two exchangers. For the case when the flow rate distribution was not controlled, the effect of viscosity differences between a colder and warmer exchanger was investigated. The short term effects of letting the vertical heat source rest during the warm summer months was then tested. Lastly, the results of the model was compared to a simple 'rule of thumb' that have been used in the industry for this kind of combined system. The results show that using a combined system might not always result in increased performance, if the previously existing exchanger is a vertical ground-coupled heat exchanger. The effects of viscosity differences on the flow distribution seems to be negligible, especially for high net flows. Controlling the fluid flow rates seems to only be worth the effort if the the pipe lengths of the two combined exchangers differ heavily. Letting the vertical ground-coupled heat exchanger rest during summer was shown to in some cases yield an increased short-term performance in addition to the already known positive long term effects. The rule of thumb was shown to recommend smaller dimensions for combination systems than the more realistic analytical model.

During the production and transportation of oil and gas, flow assurance issues may occur due to the solid deposits that are formed and carried by the flowing fluid. Solid deposition may cause serious damage and possible failure to production equipment in the flow lines. The major flow assurance problems that are faced in the fields are concerned with asphaltene, wax and scale deposition, as well as hydrate formations. Hydrates, wax and asphaltene deposition are mostly addressed in deep-water environments, where fluid flows through a long path with a wide range of pressure and temperature variations (Hydrates are generated at high pressure and low temperature conditions). In fact, a large change in the thermodynamic condition of the fluid yields phase instability and triggers solid deposit formations. In contrast, scales are formed in aqueous phase when some incompatible ions are mixed. Among the different flow assurance issues in hydrocarbon reservoirs, asphaltenes are the most complicated one. In fact, the difference in the nature of these molecules with respect to other hydrocarbon components makes this distinction. Asphaltene molecules are the heaviest and the most polar compounds in the crude oils, being insoluble in light n-alkenes and readily soluble in aromatic solvents. Asphaltene is attached to similarly structured molecules, resins, to become stable in the crude oils. Changing the crude oil composition and increasing the light component fractions destabilize asphaltene molecules. For instance, in some field situations, CO₂ flooding for the purpose of enhanced oil recovery destabilizes asphaltene. Other potential parameters that promote asphaltene precipitation in the crude oil streams are significant pressure and temperature variation. In fact, in such situations the entrainment of solid particulates in the flowing fluid and deposition on different zones of the flow line yields serious operational challenges and an overall decrease in production efficiency. The loss of productivity leads to a large number of costly remediation work during a well life cycle. In some cases up to $5 Million per year is the estimated cost of removing the blockage plus the production losses during downtimes. Furthermore, some of the oil and gas fields may be left abandoned prematurely, because of the significance of the damage which may cause loss about $100 Million. In this dissertation, we developed a robust wellbore model which is coupled to our in-house developed compositional reservoir model (UTCOMP). The coupled wellbore/reservoir simulator can address flow restrictions in the wellbore as well as the near-wellbore area. This simulator can be a tool not only to diagnose the potential flow assurance problems in the developments of new fields, but also as a tool to study and design an optimum solution for the reservoir development with different types of flow assurance problems. In addition, the predictive capability of this simulator can prescribe a production schedule for the wells that can never survive from flow assurance problems. In our wellbore simulator, different numerical methods such as, semi-implicit, nearly implicit, and fully implicit schemes along with blackoil and Equation-of-State compositional models are considered. The Equation-of-State is used as state relations for updating the properties and the equilibrium calculation among all the phases (oil, gas, wax, asphaltene). To handle the aqueous phase reaction for possible scales formation in the wellbore a geochemical software package (PHREEQC) is coupled to our simulator as well. The governing equations for the wellbore/reservoir model comprise mass conservation of each phase and each component, momentum conservation of liquid, and gas phase, energy conservation of mixture of fluids and fugacity equations between three phases and wax or asphaltene. The governing equations are solved using finite difference discretization methods. Our simulation results show that scale deposition is mostly initiated from the bottom of the wellbore and near-wellbore where it can extend to the upper part of the well, asphaltene deposition can start in the middle of the well and the wax deposition begins in the colder part of the well near the wellhead. In addition, our simulation studies show that asphaltene deposition is significantly affected by CO₂ and the location of deposition is changed to the lower part of the well in the presence of CO₂. Finally, we applied the developed model for the mechanical remediation and prevention procedures and our simulation results reveal that there is a possibility to reduce the asphaltene deposition in the wellbore by adjusting the well operation condition. / text

The development of a chip-based sensor array composed of individually addressable polystyrene-polyethylene glycol and agarose microspheres has been demonstrated. The microspheres are selectively arranged in micromachined cavities localized on silicon wafers. These cavities are created with an anisotropic etch and serve as miniaturized reaction vessels and analysis chambers. The cavities possess pyramidal pit shapes with trans-wafer openings that allow for both fluid flow through the microreactors/analysis chambers as well optical access to the chemically sensitive microspheres. Identification and quantification of analytes occurs via colorimetric and fluorescence changes to receptor and indicator molecules that are covalently attached to termination sites on the polymeric microspheres. Spectral data is extracted from the array efficiently using a charge-coupled device (CCD) allowing for the near-real-time digital analysis of complex fluids. The power and utility of this new microbead array detection methodology is demonstrated here for the analysis of complex fluids containing a variety of important classes of analytes including acids, bases, metal cations, sugars and antibody reagents. The application of artificial neural network analyses to the microbead array is demonstrated in the context of pH measurements. To assess the utility of the analysis and gain an understanding of the molecular level design of the sensor, parameters such as the choice of the indicator dyes, array size, data pre-processing techniques, as well as different network types and architectures were evaluated. Additionally, the development of miniaturized chromatographic systems localized within individual polymer microspheres and their incorporation into an array is reported. The integrated chromatographic and detection concept is based on the creation of distinct functional layers within the microspheres. Such beads have been incorporated into the array platform and used for speciation and concentration determination of aqueous metal cation solutions. / text

M. Tech. Chemistry. / Objectives of this study was to assess the levels of heavy metals in bovine meat, hair, sediment, peat and water from the study areas using ICP-MS and internal standard calibration.The specific objectives are to: collect hair and meat of impala and cattle, sediment, peat, soil and water samples; digest samples; determine the level of some of the following heavy metals Cd, Cr, Cu, Hg, Mn, Pb, Sr, U, V depending on the background information on the above samples; compare the levels of Hg in sediment and peat using ICP-MS and Zeeman mercury spectrometer; determine the limit of detection of trace elements in different matrices using ICP-MS; establish correlations among concentrations of heavy metals in specified samples.

Superoxide, the product of the one-electron reduction of dioxygen, is a molecule of enormous importance. It participates in a variety of critical physiological processes and is also an important component of fuel cells where it is an intermediate in the cathodic reaction. However, the electrochemical behavior of superoxide, mainly its reduction, is not well understood. Here, the electrochemical behavior of superoxide has been investigated in acetonitrile on glassy carbon electrodes, through cyclic voltammetry experiments. By stabilizing the electrogenerated superoxide, aprotic solvents afford an opportunity to study its electrochemical reactions further. Superoxide was generated electrochemically from dioxygen at the first voltammetric peak. In the presence of hydrogen-bond donors (water, methanol, 2-propanol), the superoxide forms a complex with the donor resulting in a positive shift in the formal potential which can be analyzed to obtain formation constants for these complexes. Stronger acids (2,2,2- trifluoroethanol, 4-tert-butylphenol) result in protonation of superoxide followed by reduction to produce HO₂-. On scanning to more negative potentials a second peak is observed which is irreversible and extremely drawn out along the potential axis indicating a small value of the transfer coefficient α. Addition of hydrogenbond donors, HA, brings about a positive shift in this peak, without a noticeable change in shape. The reaction occurring at the second peak is a concerted proton-coupled electron transfer (PCET) in which the electron is transferred to superoxide and a proton is transferred from HA to superoxide forming HO₂- and A- in a concerted process. We estimate the standard potential for this reaction for the case of water as the donor. This value suggests that the reaction at the second peak occurs at very high driving forces. Kinetic simulations using both Butler-Volmer and Marcusian schemes were performed to estimate the kinetic parameters. The unusually low rate constants obtained suggest high nonadiabaticity for this PCET reaction. The reaction was also found to proceed with an unusually large reorganization energy. Consistent with a PCET, a kinetic isotope effect, HA vs. DA, was detected for the three hydrogen-bond donors.

Requirements of high performing engine oil are today necessary since the development of new machinery with modern standardsis a cutting edge technology demanding highly optimized components. One way of increasing the lubricating properties of engineoil is through the addition of antioxidants. Antioxidants included in lubricants have a number of functions, one being buffering theinorganic acids sulphuric acid and nitric acid.A novel method expected to lower the hydrogen ion concentration in acidified engine oil was evaluated in this thesis. Thecapability of four different types of cation exchangers to serve as complements for buffering additives in heavy vehicle engineswas assessed. Two cation exchangers were weak and two were strong. The analysis techniques used to evaluate what effect thecation exchangers have on engine oil were standard test method ASTM D4739, for measurements of the total base number (TBN),and inductively coupled plasma – atomic emission spectroscopy (ICP-AES). With ASTM D4739 it was found that weak cationexchangers give positive results with respect to the ability to decrease the hydrogen ion concentration in acidified engine oil.However, after begin subjected to strong cation exchangers, ASTM D4739 indicated that the hydrogen ion concentration in theacidified engine oil remains the same or increases.With additional literature studies of a variety of cation exchangers currently on the market, further optimization of the cationexchanging material could likely be achieved. In addition, the preparation method used during the evaluation of the cationexchangers should be optimized to give more reliable results.

Current drugs used to treat Congestive Heart Failure target the renin-angiotensin and adrenergic systems. Studies showed increased mortality rates in patients treated with a combination of these medications. Angiotensin-AT1 and ?2-Adrenergic receptors were shown to form receptor heteromers. Blockade of one receptor in the complex can affect the signal transmitted by the other; suggesting that ligand-based therapy is not as selective as we might think. Modulating receptor trafficking after synthesis might prove to be a valid therapeutic strategy. Unfortunately, little is known about receptor assembly and transport from Endoplasmic Reticulum to Plasma Membrane. The objectives of this study are to identify the proteins that participate in the assembly of AT1R-?2AR heteromer and the regulators of the anterograde trafficking of G-Protein Coupled Receptors. This thesis introduces the role of important targets in those poorly understood processes. The identification of such targets could lead to developing better drugs with fewer adverse effects.

Beams are among the most commonly used structural members that are encountered in virtually all systems of structural design at various scales. Mathematical models used to determine the response of beams under external loads are deduced from the three-dimensional elasticity theory through a series of assumptions concerning the kinematics of deformation and constitutive behavior. The kinematic assumptions exploit the fact that such structures do not experience significant trans- verse normal and shear strains and stresses. For example, the solution of the three- dimensional elasticity problem associated with a straight beam is reformulated as a one-dimensional problem in terms of displacements whose form is presumed on the basis of an educated guess concerning the nature of the deformation. In many cases beam structures are subjected to compressive in-plane loads that may cause out-of-plane buckling of the beam. Typically, before buckling and during compression, the beam develops internal axial force that makes the beam stiffer. In the linear buckling analysis of beams, this internal force is not considered. As a result the buckling loads predicted by the linear analysis are not accurate. The present study is motivated by lack of suitable theory and analysis that considers the nonlinear effects on the buckling response of beams. This thesis contains three new developments: (1) the conventional beam theories are generalized by accounting for nonlinear terms arising from εzz and εxz that are of the same magnitude as the von K´arm´an nonlinear strains appearing in εxx. The equations of motion associated with the generalized Euler–Bernoulli and Timoshenko beam theories with the von K´arm´an type geometric nonlinear strains are derived using Hamilton’s principle. These equations form the basis of investigations to determine certain microstructural length scales on the bending, vibration and buckling response of beams used in micro- and nano-devices. (2) Analytical solutions of the conventional Timoshenko beam theory with the von K´arm´an nonlinearity are de- veloped for the case where the inplane inertia is negligible when compared to other terms in the equations of motion. Numerical results are presented to bring out the effect of transverse shear deformation on the buckling response. (3) The development of a nonlinear finite element model for post-buckling behavior of beams.

An ultra-low dose of a drug is approximately 1000-fold lower than the dose range traditionally used to induce a therapeutic effect. The purpose of the present thesis was to broaden the knowledge of the ultra-low dose effect, that was previously identified in the opioid receptor system, by looking at whether opioids and cannabinoids interact at the ultra-low dose level, whether cannabinoid receptors themselves demonstrate the ultra-low dose antagonist effect, and whether the opioid ultra-low dose effect is maintained in a model of persistent, unavoidable pain. For experiment 1, separate groups of Long Evans rats were tested for antinociception following an injection of vehicle, the cannabinoid agonist WIN 55 212-2 (WIN), the opioid antagonist naltrexone (an ultra-low or a high dose), or a combination of WIN and naltrexone doses. Ultra-low dose naltrexone elevated WIN-induced tail flick thresholds without extending its duration of action. In experiment 2, antinociception was tested in rats following either acute or sub-chronic (7 days) injections of vehicle, WIN, ultra-low doses of the CB1 receptor antagonist rimonabant (SR 141716), or a combination of WIN and ultra-low dose rimonabant. Following the chronic experiment, striatal tissue was rapidly extracted and subjected to co-immunoprecipitation to analyse CB1 receptor coupling to G-protein subtypes. Ultra-low dose rimonabant extended the duration of WIN-induced antinociception, and attenuated the development of WIN-induced tolerance. Animals chronically treated with WIN alone had CB1 receptors predominately coupling to Gs proteins, whereas all other groups had CB1 receptors predominately coupling to Gi proteins. For experiment 3, all animals were subjected to the formalin test following either acute or sub-chronic injections of vehicle, the opiate morphine, ultra-low doses naltrexone, or a combination of morphine and ultra-low dose naltrexone. Ultra-low dose naltrexone had no significant effect on morphine-induced pain ratings in either the acute, or sub-chronic drug treatments. This thesis provides evidence that the ultra-low dose effect, including the agonist-induced G-protein coupling switch, extends to another receptor type. This effect may, therefore, be part of a generalized principle that applies to many G-protein coupled receptors. / Thesis (Ph.D, Psychology) -- Queen's University, 2007-11-05 09:31:30.162 / A portion of this research was supported by a Canadian Institutes of Health Research (CIHR) Proof of Principle Grant to M.C. Olmstead and J.J. Paquette.

Soil moisture plays a major role in the hydrologic water balance and is the basis for most hydrological models. It influences the partitioning of energy and moisture inputs at the land surface. Because of its importance, it has been used as a key variable for many hydrological studies such as flood forecasting, drought studies and the determination of groundwater recharge. Therefore, spatially distributed soil moisture with reasonable temporal resolution is considered a valuable source of information for hydrological model parameterization and validation. Unfortunately, soil moisture is difficult to measure and remains essentially unmeasured over spatial and temporal scales needed for a number of hydrological model applications. In 2002, the Gravity Recovery And Climate Experiment (GRACE) satellite platform was launched to measure, among other things, the gravitational field of the earth. Over its life span, these orbiting satellites have produced time series of mass changes of the earth-atmosphere system. The subsequent outcome of this, after integration over a number of years, is a time series of highly refined images of the earth's mass distribution. In addition to quantifying the static distribution of mass, the month-to-month variation in the earth's gravitational field are indicative of the integrated value of the subsurface total water storage for specific catchments. Utilization of these natural changes in the earth's gravitational field entails the transformation of the derived GRACE geopotential spherical harmonic coefficients into spatially varying time series estimates of total water storage. These remotely sensed basin total water storage estimates can be routinely validated against independent estimates of total water storage from an atmospheric-based water balance approach or from well calibrated macroscale hydrologic models. The hydrological relevance and implications of remotely estimated GRACE total water storage over poorly gauged, wetland-dominated watershed as well as over a deltaic region underlain by a thick sand aquifer in Western Canada are the focus of this thesis. The domain of the first case study was the Mackenzie River Basin wherein the GRACE total water storage estimates were successfully inter-compared and validated with the atmospheric based water balance. These were then used to assess the WATCLASS hydrological model estimates of total water storage. The outcome of this inter-comparison revealed the potential application of the GRACE-based approach for the closure of the hydrological water balance of the Mackenzie River Basin as well as a dependable source of data for the calibration of traditional hydrological models. The Mackenzie River Basin result led to a second case study where the GRACE-based total water storage was validated using storage estimated from the atmospheric-based water balance P-E computations in conjunction with the measured streamflow records for the Saskatchewan River Basin at its Grand Rapids outlet in Manitoba. The fallout from this comparison was then applied to the characterization of the Prairie-wide 2002/2003 drought enabling the development of a new drought index now known as the Total Storage Deficit Index (TSDI). This study demonstrated the potential application of the GRACE-based technique as a tool for drought characterization in the Canadian Prairies. Finally, the hydroinformatic approach based on the artificial neural network (ANN) enabled the downscaling of the groundwater component from the total water storage estimate from the remote sensing satellite, GRACE. This was subsequently explored as an alternate source of calibration and validation for a hydrological modeling application over the Assiniboine Delta Aquifer in Manitoba. Interestingly, a high correlation exists between the simulated groundwater storage from the coupled hydrological model, CLM-PF and the downscaled groundwater time series storage from the remote sensing satellite GRACE over this 4,000 km2 deltaic basin in Canada.