The binding of aqueous solutions of sodium cholate and chenodeoxycholate with a lightly cross-linked polyacrylamide resin carrying N,N,N-trimethylammonium dodecyl chloride pendants (QPDA12) have been studied by HPLC data under various conditions. The goal of this thesis was to determine the relative enthalpic and entropic contributions to the binding that would aid in establishing the molecular basis of the process and in the development of effective resins that sequester bile salts. / The binding constants were extracted from the fit of the isotherms to the Langmuir equation and their temperature dependence was employed to evaluate the thermodynamic parameters associated with the process. The binding was endothermic and entropy-driven. Stronger binding was always associated with a higher enthalpy barrier. Enthalpy-entropy compensation was observed encompassing data for both cholate and chenodeoxycholate binding under the influence of a variety of perturbations to the solvent. A compensation temperature of 293 K was obtained, which is characteristic of processes in which water plays a central role. The parameters observed were used to rule out earlier molecular descriptions of the process, and an alternate mechanism was proposed that emphasised the significant role of hydrophobic hydration changes in the sequestering of the bile salts. / The temperature dependence studies were extended to the binding of sodium cholate with a lightly cross-linked hydrophilic resin possessing lysine-containing peptide pendant groups. In sharp contrast with the Langmuir behaviour of the isotherms found with the QPDA12 resin the binding behaviour with the peptide resin was of a complex nature. There was a very distinct sigmoidal feature in the binding process, which is the signature of cooperative binding. A weaker binding manifested itself in the latter half of the binding isotherms. An analysis of the temperature dependence revealed that the binding was exothermic throughout the isotherm. However, while the initial weak binding was in part entropy-driven, the subsequent stronger cooperative interactions resulted in binding that was associated with negative entropy changes.

The aim of this research was to investigate whether gastrointestinal parasite infections in colobus monkeys were more severe on humanized forest edges compared to non-humanized forest edges. I examined gastrointestinal parasites and fecal cortisol in red and black-and-white colobus (Procolobus rufomitratus; Colobus guereza) found in four habitat types in Kibale National Park, Uganda. Three parasite types were identified: Trichuris sp., stongyles, and Strongyloides sp. Results did not correspond to the expectation that humanized forest edges increase parasite infection; only two measures of parasite infection in the red colobus corresponded to this expectation. Results also did not correspond to the expectation that edge habitat causes an increase in parasite infection. Factors that may contribute to parasite infections are discussed and I concluded that broad classifications (e.g. “humanized”) may be too general to identify consistent differences in infections, as factors specific to each habitat and/or group may influence parasite infection. / Cette thèse a pour but d’examiner si les infections gastro-intestinales causées par des parasites chez les singes colobus sont plus sévères chez des individus à la frontière de la forêt près d’endroits habités ou à la frontière de la forêt loin des êtres humains. J’ai examiné des parasites gastro-intestinaux et le taux de cortisol dans les excréments de deux espèces de singes colobus, le colobus rouge (Procolobus rufomitratus) et le colobus noir et blanc (Colobus guereza), dans quatre types d’habitats différents au sein du Parc National de Kibale, en Ouganda, Afrique de l’est. Trois catégories de parasites furent identifiés: Trichuris sp., stongyles, et Strongyloides sp. Mes résultats ne supportent pas l’hypothèse de départ que la frontière de la forêt ayant une présence humaine plus élevée augmente le taux d’infection chez les singes colobus. En effet, deux mesure d’infection chez le colobus rouge confirme cette prédiction. De plus, l’hypothèse que les singes habitant la frontière de la forêt ont un taux d’infection plus élevé que les singes habitant l’intérieur de la forêt n’est pas supportée par cette étude. Il existe une énorme variété de facteurs qui influence les infections parasitaires dont je discute dans cette thèse. Je conclue que certaines classifications générales d’habitat comme « près des êtres humains » ne sont pas assez spécifiques afin de pouvoir identifier des différences constantes du taux d’infection parce que des facteurs spécifiques à chaque habitat ou groupe d’habitats peuvent influencer les infections parasitaires.

This current study is part of a larger Community-Based Participatory Research (CBPR) project that aims to 1) develop and implement the physical activity component of a school-based wellness policy, 2) evaluate the facilitators and barriers to implementation and application of the findings among a wide range of stakeholders, and 3) disseminate the findings to other stakeholders within and outside the community. The policy intervention project is being carried out collaboratively by community stakeholders and academic researchers within the Kahnawake Schools Diabetes Prevention Project, a well-established health promotion organization in the First Nations community of Kahnawake. Using data produced during the policy development phase, this current study's purpose was to explore how a group of stakeholders develop a local school physical activity policy in a participatory manner as well as the facilitators and barriers to the development process. This case study was guided by an interpretive description approach and draws upon data from documentary analysis and participant observation. The results show how a CBPR approach allowed academic researchers and community stakeholders to collaborate and develop a physical activity policy that is both evidence-based and contextually appropriate. The development process was influenced by a variety of barriers and facilitators including working within existing structures, securing appropriate stakeholders, school contextual factors, and issues of time. This research provides a process framework that others looking to develop school-based wellness policies may make use of with appropriate modifications based on their own environments. / Cette étude fait partie d'un projet de recherche participative communautaire qui vise à 1) développer et mettre en œuvre la section activité physique d'une politique de bien-être à l'école, 2) évaluer les facilitateurs et les obstacles à la mise en œuvre et l'application des résultats parmi un grand nombre de parties prenantes, et 3) diffuser les résultats à d'autres parties prenantes à l'intérieur et à l'extérieur de la communauté. Le projet est effectué en collaboration avec les intervenants communautaires et les chercheurs universitaires affiliés avec Kahnawake Schools Diabetes Prevention Project, une organisation de promotion de la santé qui est bien établie dans la communauté des Premières Nations de Kahnawake. En utilisant les données produites au cours de la phase de développement de la politique, le but de cette étude était d'explorer comment un groupe d'intervenants a produit une politique d'activité physique à l'école d'une manière participative ainsi que les facilitateurs et les obstacles au processus de développement. Cette étude de cas fut guidée par une approche interprétative descriptive et s'appuie sur des données provenant de sources documentaires et observation participante. Les résultats montrent comment une approche de recherche participative communautaire a permis aux chercheurs universitaires et aux intervenants communautaires de collaborer et de développer une politique d'activité physique qui est à la fois fondée sur des données probantes et adaptée aux circonstances. Le processus de développement a été influencé par plusieurs obstacles et facilitateurs, notamment le travail parmi les structures existantes, la disponibilité d'intervenants appropriés, l'observation de facteurs contextuels scolaires et le respect des contraintes de temps. Cette recherche fournit un cadre de référence pour tous ceux qui cherchent à développer des politiques de bien-être en milieu scolaire; ils pourront par la suite ajouter les modifications nécessaires en fonction de leurs propres environnements.

The knowledge of how cells interact with man-made materials is crucial for the design of specialized biomaterials. These interactions are mainly based on the physical properties of that material. In order to study the effect of these properties, polyelectrolyte multilayers were used: these are coatings able to mask any material, which are carefully built from the bottom up using the layer-by-layer technique. The biologically relevant physical properties of these coatings are tuneable by altering conditions of their build up, such as the pH and/or salt concentration. Initially, multilayers of PDADMAC (poly(diallyl dimethyl ammonium chloride)) and PSS (poly(styrene-4-sulfonate), PAA (poly(acrylic acid)) and PDADMAC, PAH (poly(allylamine hydrochloride)) and PAA, and PSS and PAH were prepared under a variety of pH conditions. The physical properties of these films were measured and it was discovered that PAA/PAH multilayers exhibited the largest variations in surface energy (Δ30 mJ/m2) and rigidity (Δ8 GPa). Investigating cell response to different coatings is time consuming, expensive, and prone to error. Therefore, a device was designed that slowly varied the fabrication pH of PAA and PAH orthogonally to each other, providing a technique that enabled the construction of large 2-dimensional films with all possible pH fabrication conditions. Physical property maps were made, and it was discovered that film rigidity was the most crucial determinant for cell survival, and that the neural cells prefer films with a moderate modulus (~500-800 kPa). The ability to reversibly and non-invasively control the physical properties important for bio-activity enables interesting engineering opportunities. By functionalizing PAA with (poly(disperse red 2)) to make pDR2A, and layering it with PDADMAC, the surface energy was reversibly altered by 3 mJ/m2 using linearly polarized light. These changes were stable for days and were attributed to chromophore alignment inside of the film, as measured by birefringence. These results provide some insight on cell-material interactions; however, more importantly, they provide new tools for the investigation of such a complex problem. / La connaissance des interactions entre les cellules et les matériaux synthétiques est cruciale pour la conception de biomatériaux spécialisés. Ces interactions sont principalement basées sur les propriétés physiques des matériaux. Afin d'étudier ces effets, des polyélectrolytes multicouches ont été utilisés. Ces polymères sont capables de couvrir des matériaux en étant soigneusement construit du bas en haut en utilisant une technique couche par couche. Les propriétés physiques d'intérêt biologique de ces revêtements sont possible en modifiant les conditions de leur accumulation, tels que le pH et/ou la concentration de sel. Initialement, des couches de PDADMAC (poly (chlorure de diallyldiméthylammonium)) et PSS (poly (styrène-4-sulfonate), PAA (poly (acide acrylique)) et PDADMAC, PAH (poly (chlorhydrate allyamine)) et AAP, et PSS et les HAP ont été construite sous une variété de conditions de pH. Les propriétés physiques de ces films ont été mesurées et nous avons trouvé que les multicouches HAP/AAP présentaient les plus grandes variations de l'énergie de surface (Δ30 mJ/m2) et la rigidité (Δ8 GPa). Les enquêtes sur les réponses cellulaires aux différents revêtements sont longues et couteuse en plus d'être sujet à l'erreur. Par conséquence, un dispositif a été conçu qui a changé le pH de fabrication de l'AAP et les HAP orthogonalement un à l'autre, cette technique a permis la construction de filmes deux dimensionnelles sur grandes dimensions avec toutes les conditions de fabrication possibles selon la variation du pH. Des cartes des propriétés physiques ont été faites, et il a été découvert que la rigidité des films est le facteur le plus crucial pour la survie des cellules et que les cellules neurales préfère les films avec un module modérée (~ 500-800 kPa). La capacité de contrôler les propriétés physiques importantes de façon réversible et non invasive pour la bio-activité permet des possibilités techniques intéressantes. En fonctionnalisant l'AAP avec du Disperse Red 2 acrylate pour faire pDR2A, des couches construites avec du PDADMAC démontrent une énergie de surface qui peut être modifiée réversiblement de 3 mJ/m2 utilisant de la lumière polarisée linéairement. Ces changements sont stables pendant des jours et sont attribuable à l'alignement intérieur des chromophores du film telle que mesurée par la biréfringence.Ces résultats donnent une de d'information sur les interactions entre les cellules et les matériaux, mais plus important encore, fournissent des nouveaux outils pour l'étude d'un tel problème complexe.

Previous studies reported a unique direction of lamellar twist in banded spherulites of polymers with main-chain chirality, which lead to the suggestion that a correlation exists between the handedness of the helical chain and the twist direction. However, these proposals were presented without identifying underlying reasons for such a correlation. Hence, the goal of this thesis was to identify morphological features that could be ascribed to main-chain chirality, which, in turn, would provide insight concerning the transmission of chirality to asymmetries in various levels of crystalline morphology. / Studies at the molecular level, based on chain-packing simulations showed that main-chain chirality leads to the formation of helices of a given handedness but indicated that the helix handedness does not have the ability to generate asymmetric habits at the next higher dimensional level, which is the chain-folded lamella. This was confirmed by the TEM studies of solution-grown single crystals of the R and S polyenantiomers of poly(epichlorohydrin) (PECH), poly(propylene oxide) (PPrO) and poly(3-hydroxyvalerate) (PHV). / Electron diffraction studies established that chain tilting (considered a root cause of lamellar twisting) is absent in these single crystals. However, this does not eliminate the possibility of an induced chain tilting in stems at growth fronts during fast crystallization from the melt. Indeed, optical microscopy studies of the behavior of spherulites grown from the melt established that the lamellae (fibrils) twist, uniquely in either a right- or left-handed fashion, depending on the chiral identity (R or S) of the polyenantiomer. Although the handedness of the lamellar twist of the R and S polyenantiomers of PECH and PPrO both showed a direct correlation with the handedness of the helical chain, this correlation is not universal. While poly(3-hydroxybutyrate) (PHB) and PHV both form left-handed helices, the directions of lamellar twist are left- and right-handed, respectively. It was also demonstrated that the handedness of spiral patterns developed in banded spherulites of chiral polymers is not rigorously related to the molecular chirality. The overall conclusion is that determination of the ultimate origin(s) of lamellar twisting in banding of polyenantiomers requires further investigations.

Suspensions of rod-like cellulose microcrystallites, 50-250 nm in length and $ sim$7 nm in width, and with negatively charged sulfate groups on the surface have been prepared. When the concentration of cellulose microcrystallites exceeds a critical value, the suspension separates into two phases, forming an upper isotropic phase and a lower chiral nematic anisotropic phase. The critical concentration for phase separation is very sensitive to the ionic strength, particle size, polydispersity of particles, counterion species, and preparation conditions. When the suspension is in pure water and in the biphasic region, the coexisting concentrations in both phases increase with the increase of total cellulose concentration. Suspensions with different counterions have different critical concentrations for phase separation. The critical concentration increases in the order $ rm H sb3{O sp+} < {Na sp+} < {K sp+} < Cs sp+$ for inorganic counterions, and generally increases with increasing counterion size for some organic counterions. The salt-form suspensions demonstrate a good stability with temperature, but the acid-form suspension is unstable at temperatures higher than $50 sp circ$C. The suspensions show induced circular dichroism in the presence of dye, such as Congo red. The anisotropic phase has a very strong negative ICD peak when viewed along the chiral nematic axis, and the peak is much weaker when viewed at right angles to the axis. The isotropic suspension shows a small positive ICD peak. The behavior of the phase separation was compared with the theoretical predictions of Stroobants et al., and a relatively good agreement was obtained between theory and experimental data for suspensions in pure water.

In this thesis, we formulate a new 3-dimensional planetary geostrophic (PG) ocean general circulation model in spherical coordinates for use in ocean-climate studies. The model equations consist of full prognostic temperature and salinity equations and diagnostic momentum equations. The model is verified by comparison with results obtained by the well known Bryan-Cox model at coarse resolution. Extensive process studies are carried out to determine the roles played by various processes in determining the thermocline structure and the thermohaline circulation, especially the role of convective overturning. A secondary circulation theory which treats the thermohaline circulation as a geostrophic flow instead of frictional current is proposed, and the implications of the results to 2-dimensional latitude/depth models are discussed. / The model is also used to examine the stability and variability of the thermohaline circulation, especially the role played by air-sea heat flux at the surface. We show that the large reduction in the surface heat flux under mixed boundary conditions (restoring on temperature and flux on salinity) is essential for the occurrence of the "polar halocline catastrophe" (F. Bryan. 1986). Replacing the infinite heat capacity atmosphere implied by mixed boundary conditions with an atmosphere that can adjust thermally to the ocean, the amount of the heat flux reduction is less and thus the polar halocline catastrophe is less likely to occur; when it does occur, it is less severe. This is demonstrated by coupling our model to a simple zero heat capacity atmosphere (Schopf, 1983). Instead of a total collapse of the thermohaline circulation, the results show a decaying oscillation of 20 years period. / The ocean model is next coupled to a thermodynamic sea ice model to examine the effect of sea ice on the stability and variability of the thermohaline circulation. A robust 17-year period oscillation is obtained, and a new mechanism involving a feedback between ice cover and temperature is proposed. Conceptual models are formulated for further interpretation of the results, and to compare the thermal insulation and salinity rejection effects due to an anomalous ice cover, on the density of the surface water. The heat budget required for ice formation leads to a constraint on the convective overturning, and hence the transfer of heat and salt from the deep ocean to the bottom of the ice. As a result, the thermal insulation effect is dominant, at least for the case of annual mean surface forcing examined here.

This thesis is made of two parts. In the first part, we study pattern formations and dissipation of energy and matter by using hyperbolic reaction-diffusion equations for reacting systems. Two-dimensional hyperbolic reaction-diffusion equations are numerically solved for the Selkov model and the Brusselator. It is shown that the evolution equations used can give rise to various kinds of patterns such as hexagonal structures, stripes, maze structures, chaotic structures, etc., depending on the values of the reaction-diffusion number and the initial and boundary conditions. The values of the entropy production computed indicate that the system maintains the particular organized local structures at the expense of energy and matter. However, when the system produces a chaotic pattern, the entropy production is lower than the locally organized structures. The phase speed of travelling oscillating chemical waves can be obtained from the linearized hyperbolic reaction-diffusion equations. The Luther-type speed formula is obtained in the lowest order approximation in the case of the Brusselator. The two-dimensional power spectra computed for chaotic patterns still preserve some kind of symmetry. / In the second part of this thesis, the generalized hydrodynamics is applied to calculate the shock profiles, shock widths, and calortropy production for a Maxwell gas. Shock solutions are shown to exist for all Mach numbers. This is in contrast to the Grad moment equation method which does not admit shock solution for $N sb{M} ge 1.65$ and to the method of Anile and Majorana which breaks down for $N sb{M} ge 2.09.$ The energy dissipation in the shock is shown to increase with the Mach number as a power law of the form $(N sb{M} - a) sp{ alpha}$ where a and $ alpha$ are real constants.

<p> Phthalates have attained a great deal of attention recently due to their reported association with endocrine system disturbances. Currently, advanced oxidation processes (AO/RPs) are being considered for use in remediating these chemical contaminants from anthropogenic waste waters; however, there is little known about the kinetics of AO/RP radical reactions with phthalates in water. In this work we investigated the reaction kinetics of the hydroxyl radical, hydrated electron and sulfate radical with a series of phthalates and phthalate monoester metabolites using electron pulse radiolysis. A direct relationship was found between the molecular complexity of the phthalate esters and the natural logarithm of their corresponding hydroxyl radical rate constant. Phthalate monoester metabolites were found to have higher rate constants than the corresponding phthalate diesters of similar molecular complexity. No structural relationship was found between phthalate esters and their corresponding hydrated electron rate constant.</p>

An uncoupled, modified Hibler ice model has been applied to the Gulf of St. Lawrence for three different winters of varying severity, in order to examine interannual sea ice variability. The simulation was initialized with observed November sea surface temperatures, and forced by weekly geostrophic winds, monthly averaged meteorological data and model geostrophic surface currents. / Results showed a general correlation with observations, reproducing differences in the sea ice cover between the years chosen. Neglecting oceanic effects caused excessive ice formation in the northwest Gulf and produced discrepancies between the observed and modelled ice edge. / Sensitivity studies revealed a high sensitivity to variations in both the forcing fields and the model free parameters. Further modelling studies must include a coupled ocean component, and force the ice component with weekly meteorological data to improve the accuracy of the prediction.