Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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The pulsed field gradient fourier transform nuclear magnetic resonance (PFG-FTNMR) method to measure translational diffusion coefficients in multicomponent systems has been applied to amphiphilic molecules forming liquid crystalline phases. By analyzing the concentration dependence of the diffusion coefficients of water and amphiphile in a micellar system of N,N-dimethyldodecy lamine oxide (DDAO) in water it was possible to conclude that the micelles formed were polydisperse in size and shape. It was also shown that solubilization of small amounts of hydrophobic molecules into the micelles induces spherical micelles of a narrow size distribution. From the magnitude of the lateral diffusion coefficient in the cubic phase of DDAO/water it was concluded that this phase is built up of bicontinous aggregates. The lipid lateral diffusion in the cubic phase of monooleoylglycerol (MO)/water has been measured. The decrease in the lateral diffusion of MO in this phase, when the water was replaced by glycerol, was ascribed to changes in viscosity in the polar region. Measurements by electron spin resonance and time-resolved fluorescence spectroscopy showed that changes in viscosity of the solvent also affected the motions in the hydrocarbon region. The diffusion coefficients of all three components in the cubic phase located in the lowwater region of the ternary system of diacylglycerol (DAG)/soybean phosphatidylcholine (SPC)/water have been determined. Conclusive evidence was provided for that this cubic phase is built up of reversed micelles containing mainly SPC in a continous matrix of mainly DAG. The effect on the phase properties of DDAO upon incorporation of the peptide gramicidin D has been investigated. It was shown that gramicidin D induces a lamellar phase at all water contents. The change in the order parameter profile of the C-2H bonds in perdeuterated DDAO upon incorporation of gramicidin D is compatible with theoretical calculations for proteins exhibiting a positive hydrophobic mismatch. A method for using the PFG FTNMR technique in measurements of the transmembrane exchange rate of small molecules in vesicular suspensions is discussed and some preliminary data is shown. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 4 uppsatser</p> / digitalisering@umu

Many Ministry of Transportation of Ontario (MTO) projects consist of construction and maintenance of reinforced concrete structures. Where appropriate test methods exist, MTO has been moving towards use of performance-based specifications for durability control of concrete. MTO currently uses ASTM C1202 (RCPT) coulomb values to assess concrete durability. This test requires taking cores, so replacing this test with a faster non-destructive technique is important. The main focus of this program was to study the Wenner probe surface resistivity as a non-destructive test device and evaluate the potential for replacement of RCPT with the Wenner resistivity. This research program consists of the determination of RCPT values, water sorptivity coefficients and electrical resistivities (bulk and surface) of nine concrete mixtures. In addition, the development of the Wenner probe instrument was studied. As well, correlations between resistivity and ASTM C1202 and C1585 are provided followed by technical recommendations for improving the Wenner test.

Many Ministry of Transportation of Ontario (MTO) projects consist of construction and maintenance of reinforced concrete structures. Where appropriate test methods exist, MTO has been moving towards use of performance-based specifications for durability control of concrete. MTO currently uses ASTM C1202 (RCPT) coulomb values to assess concrete durability. This test requires taking cores, so replacing this test with a faster non-destructive technique is important. The main focus of this program was to study the Wenner probe surface resistivity as a non-destructive test device and evaluate the potential for replacement of RCPT with the Wenner resistivity. This research program consists of the determination of RCPT values, water sorptivity coefficients and electrical resistivities (bulk and surface) of nine concrete mixtures. In addition, the development of the Wenner probe instrument was studied. As well, correlations between resistivity and ASTM C1202 and C1585 are provided followed by technical recommendations for improving the Wenner test.

Biodegradable, edible wheat gluten films offer a renewable alternative to plastic food packaging or can be incorporated directly in the food product. Wheat gluten is a good option because it forms a fibrous network, lending strength and elasticity to films. The goal of this research project was to produce, with a water-based film formulation and methodology, smooth, homogeneous wheat gluten films with low water vapour permeability (WVP). The water-based film formulation also served to compare the FT Wonder wheat cultivar, grown in Ontario, to commercially produced wheat gluten and determine the effect of wheat source on the film properties, surface morphology, surface hydrophobicity, WVP, and film swelling in water for different pH, temperature and casting surface conditions. Fluorescence, SPR, and casting formulation viscosity provided preliminary information on the mechanism of film formation and on gluten protein structure induced by modifying the film formulation. This research provides an alternate use for some Ontario wheat cultivars based on their properties in films compared to commercial sources of gluten. As a result, using Ontario cultivars to prepare gluten film packaging material has potential as an alternate source of income for Ontario farmers. This research also defines the film properties for gluten films produced from aqueous solutions, helping to identify processing parameters that could bring gluten films on par with plastic packaging and make gluten films a viable alternative food packaging material. Finally, it was determined that the water vapour permeability of wheat gluten films was not correlated to film surface contact angle.

The main objective of this thesis was to investigate the in vivo relevance of membrane transporters and cytochrome P450 (CYP) 3A4-mediated metabolism in the intestine and liver for the bioavailability of drugs in humans after oral administration. In the first part of the thesis, the main transport mechanisms involved in the intestinal absorption and bioavailability were investigated for fexofenadine, a minimally metabolized drug, which is a substrate for P-glycoprotein (P-gp) and members of organic anion transporting polypeptide (OATP) family. Jejunal perfusion studies revealed that co-perfusion with verapamil increased the bioavailability of fexofenadine by decreasing the first-pass liver extraction as the low intestinal permeability was unchanged by the transport inhibitors studied. The mechanism behind the interaction probably involves inhibition of OATP-mediated sinusoidal uptake and/or P-gp-mediated canalicular secretion of fexofenadine. Results from the Caco-2 model supported that the intestinal absorption of fexofenadine is mainly determined by the low passive permeability of the drug, even though fexofenadine clearly is a P-gp substrate. In the second part of the thesis, the effect of repeated oral administration of the P-gp and CYP3A4 inducer St. John’s wort on the in vivo intestinal permeability and presystemic metabolism of the dual P-gp and CYP3A4 substrate verapamil was investigated in a jejunal perfusion study. St. John’s wort decreased the bioavailability of the enantiomers of verapamil by inducing the CYP3A4-mediated presystemic metabolism, probably mainly in the gut. It was also concluded that induction of efflux transporters, such as P-gp, does not affect the intestinal transport or the gut wall extraction of high permeability substrates like verapamil. Data from Caco-2 cells with induced CYP3A4-activity supported these findings. The plasma levels of the enantiomers of norverapamil also decreased despite an increased formation, which was attributed to induction of CYP3A4 and/or other metabolic routes.

This study concentrates on the modelling of three phase flow and miscible CO2 flooding in pore networks that captures the natural porous medium of a reservoir. That is to say, the network, that is a Matlab code, consists of different sided triangles which are located randomly through the grids. The throats that connect the pores are also created by the model. Hence, the lengths and the radii of the throats are varying. The network used in this research is assumed to be representative of mixed-wet carbonates in 2-D. Mixed wettability arises in real porous media when oil renders surfaces it comes into prolonged contact with oil-wet while water-filled nooks and crannies remain water-wet. The model developed is quasi-static approach to simulate two phase and three phase flows. By this, capillary pressures, relative permeabilities, saturations, flow paths are determined for primary drainage, secondary imbibition, and CO2 injection cases. To calculate the relative permeability, capillary entry pressures are first determined. Then, hydraulic conductances and flow rates of the network for each grid are obtained. Phase areas and saturations are also determined. It is accepted that the displacement mechanism in drainage and CO2 injection is piston-like whereas in imbibition it is either piston-like or snap-off. The results of the model are compared with the experimental data from the literature. Although, the pore size distribution and the contact angle of the model are inconsistent with the experimental data, the agreement of the relative permeabilities is promising. The effect of contact angle in the same network for three phase flow where immiscible CO2 is injected as a third phase at supercritical temperature (32 &deg / C) is investigated. And it is found that, the increase in the intrinsic angles causes decrease in relative permeability values. As another scenario, two phase model is developed in which miscible CO2 &amp / #8211 / water is flooded after the primary drainage of the same 2-D network at supercritical temperature (32 &deg / C). This case is compared with the previous case and the effects of miscibility are investigated such that it causes the relative permeability values to increase. Adsorption is another concern of which its effects are analyzed in a single pore model. The model is compared with the reported experimental data at high temperature and pressures. A reasonable fit is obtained.

In this investigation, SCCs were prepared by keeping the total mass of cementitious materials (cement and fly ash) constant at 500 kg/m3, in which 30, 40, 50, 60, and 70% of cement, by weight, was replaced by the high-lime and low-lime fly ash. For comparison, a control SCC mixture without any fly ash was also produced. The fresh properties of the SCCs were observed through, slump flow time and diameter, V-funnel flow time, L-box height ratio, U-box height difference, segregation ratio and the rheological parameters (relative yield stress and relative plastic viscosity). Relations between workability and rheological parameters were sought. Setting times and temperature rise of the SCC were also determined. The hardened properties included the compressive strength, split tensile strength, drying shrinkage and permeation properties (absorption, sorptivity and rapid chloride permeability tests) up to 360 days. The results obtained indicated that it is possible to produce SCC with a 70% of cement replacement by both types of fly ash. The use of high volumes of fly ash in SCC not only improved the workability and permeability properties but also made it possible to produce concretes between 33-40 MPa compressive strength at 28 days.

Thermal management and energy input are required to maintain working fluids, i.e., liquefied natural gas, liquid nitrogen, and multi-phase fluids within their optimal working conditions. Increasing a pipes thermal resistance, e.g., utilizing vacuum insulation, is one method of minimizing energy input. A dual-wall concentric pipe employing a vacuum in the annulus, along with low emissivity surface coatings, is an achievable and economically viable solution. In this study, an experimental setup was designed and utilized to measure the air leakage mass flow rate for single-wall unloaded and mechanically loaded dual-wall fiber reinforced polymeric composite specimens. The mass flow rates were used to develop intrinsic permeability coefficients to quantify leakage, and to determine the maximum serviceable pipe length for a mechanical vacuum pump. In addition, thermal resistance equations were developed to quantify the theoretical heat loss, and an economic study was performed to ascertain the viability for three applications. / Applied Mechanics