This research thesis reports experimental work done to design a stable magneticmicroemulsion of ionic liquid in 2-ethylhexyl laurate with the help of an ionic surfactant andan alcohol co-surfactant. The ionic liquids tested were based on a 1,3-dialkylimidazoliumcation with different alkyl chain lengths and a tetrachloroferrate anion ([FeCl4]+) to ensure theemulsion is sensitive to applied magnetic fields. Tests of solubility of these ionic liquids havebeen performed in different solvents and oils. Emulsification tests have been done withdifferent dispersing medium, surfactants as well as with different components quantities tofind the best composition possible. Polarity and chain length of alkyl radicals in ionic liquidsand hydrocarbons in alcohol co-surfactants were proved to affect the emulsification process.Shorter chains, and higher polarity of [C1C2im]+ [FeCl4]- (at 1wt%) combined with [C1C12im]+[FeCl4]- surfactant (between 3 and 5wt%) and non-polar 1-Hexanol co-surfactant (at 10 wt%)were the best combination to create a stable magnetic microemulsion in 2-ethylhexyl laurate. Applications for this microemulsion could vary from improved oil recovery to transport ofmaterials in liquid medium for examples and have all in common a better and tunablecontrollability of the used liquid via magnetic fields. / Denna forskningsuppsats rapporterar experimentellt arbete som gjorts för att designa enstabil magnetisk mikroemulsion av jonisk vätska i 2-EtylHexyllaurat med hjälp av ett jonisktytaktivt ämne och ett alkoholsamverkande ytaktivt ämne. De joniska vätskorna som testadesvar baserade på en 1,3-dialkylimidazoliumkatjon med olika alkylkedjelängder och entetraklorferratanjon ([FeCl4]+) för att säkerställa att emulsionen är känslig för applicerademagnetfält. Tester av lösligheten av dessa joniska vätskor har utförts i olika lösningsmedel ocholjor. Emulgeringstester har gjorts med olika dispergeringsmedium, ytaktiva ämnen samt medolika mängd komponenter för att hitta bästa möjliga sammansättning. Polaritet ochkedjelängd för alkylradikaler i joniska vätskor och kolväten i alkoholsamverkande ytaktivaämnen visade sig påverka emulgeringsprocessen. Kortare kedjor och högre polaritet för[C1C2im]+[FeCl4]- (vid 1 wt%) kombinerat med [C1C12im]+[FeCl4]- ytaktivt ämne (mellan 3 och 5 wt%) och opolär 1-hexanol medytaktivt medel (vid 10 wt% var den bästa kombinationen föratt skapa en stabil magnetisk mikroemulsion i 2-EtylHexyllaurat. Tillämpningar för denna mikroemulsion kan variera från förbättrad oljeutvinning tilltransport av material i flytande medium till exempel och har alla gemensamt en bättre ochavstämbar styrbarhet av den använda vätskan via magnetfält.

Controlled radical polymerization (CRP) can be viewed as the middle ground between living anionic polymerization (LAP) and conventional free radical polymerization (FRP). It combines the precise control over polymer structure offered by LAP, under a tolerant reaction condition similar to FRP. One of the most studied CRP is atom transfer radical polymerization (ATRP), with over 10,000 papers published since its introduction in 1995. Despite the numerous studies, knowledge on its fundamental mechanism is still lacking, as evident from the lack of expression for full MWD and polydispersity that account for termination reaction. Since termination is unavoidable in ATRP, the existing expressions give inaccurate predictions as dead chains accumulate. In this study, we derived expressions for full MWD at low conversion and for polydispersity. These expressions allow us to quantify and gain better understanding on the contribution of termination. In addition, the resulting polydispersity expression shows better agreement than the existing equation when correlated with experiment data. In addition to the aforementioned questions, there are also controversies regarding the kinetics of surface-initiated ATRP, with researchers divided into two schools of theories. We evaluated the validity of these theories by comparing their predictions to experimental trends. Both theories were found to be inadequate in explaining all the experimental observations, thus triggering an investigation of the graft density. Graft density is an important determining property for polymer brushes, yet little is known about what affects its final value. Through simulations, we investigated the effect of experiment factors on the grafting density. A decrease in the amount of deactivator is found to decrease the grafting density, which could be explained by an increase in the number of monomers added per activation cycle. This knowledge allows us to explain the conflicting experiment observations regarding the growth trends of polymer layers reported in the literatures. / Thesis / Doctor of Philosophy (PhD) / Polymer materials are used almost everywhere in our daily life from clothing to water bottle. This wide range of applications owes to the nearly infinite possible properties that polymer can possess. Different polymerization processes to synthesize polymers have their own weaknesses and strengths. Herein we investigated the fundamental mechanism of one of the currently most attractive polymerization systems, atom transfer radical polymerization (ATRP). This process allows the synthesis of polymers with precisely tailored chain microstructures, making it possible to create polymer with sophisticated properties. Using modeling approaches, we derived explicit expressions for determining chain properties, allowing detailed investigation of how various factors affect these properties. Through these investigations, we obtained better understanding on the mechanism of ATRP in solution and on surface. This knowledge is crucial in providing insight and guiding experimental designs for better control over the material properties.

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This study was conducted to identify and characterize rumen bacteria that are able to degrade the toxic compound, 3-hydroxy-4(lH)-pyridone (3,4 DHP), that is produced in the rumen from mimosine. Mimosine is a non-protein amino acid that is found in leaves and seeds of Leucaena leucocephala, a leguminous tree used as a forage crop for ruminants in the tropics, and degradation of 3,4 DHP by ruminal microbes is critical for protection of animals from leucaena toxicity. Microbes with this capacity are, however, not ubiquitous and microbial populations in the rumens of animals in some parts of the world are unable to metabolize 3,4 DHP. Four strains of obligately anaerobic, gram-negative, rod-shaped bacteria that degrade 3,4 DHP were isolated from rumen contents from a goat in Hawaii. The isolates do not ferment carbohydrates, but are able to use both 3,4 DHP and its isomer, 3-hydroxy-2(lH)-pyridone (2,3 DHP), as well as arginine and histidine as substrates for growth. Comparisons of the 16S rRNA sequence from one of these isolates with sequences from a widely diverse group of bacteria agree with other information indicating that these isolates do not fit into any existing taxon. Thus, we are hereby proposing a new genus and species designation, Synergistes jonesii, for these organisms.

Heteropolymeric O antigen (O-Ag)-capped lipopolysaccharide is the principal constituent of the Gram-negative bacterial cell surface. It is assembled via the integral inner membrane (IM) Wzx/Wzy-dependent pathway. In Pseudomonas aeruginosa, Wzx translocates lipid-linked anionic O-Ag subunits from the cytoplasmic to the periplasmic leaflets of the IM, where Wzy polymerizes the subunits to lengths regulated by Wzz1/2. The Wzx and Wzy IM topologies were mapped using random C-terminal-truncation fusions to PhoALacZα, which displays PhoA/LacZ activity dependent upon its subcellular localization. Twelve transmembrane segments (TMS) containing charged residues were identified for Wzx. Fourteen TMS, two sizeable cytoplasmic loops (CL), and two large periplasmic loops (PL3 and PL5 of comparable size) were characterized for Wzy. Despite Wzy PL3–PL5 sequence homology, these loops were distinguished by respective cationic and anionic charge properties. Site-directed mutagenesis identified functionally-essential Arg residues in both loops. These results led to the proposition of a “catch-and-release” mechanism for Wzy function. The abovementioned Arg residues and intra-Wzy PL3–PL5 sequence homology were conserved among phylogenetically diverse Wzy homologues, indicating widespread potential for the proposed mechanism. Unexpectedly, Wzy CL6 mutations disrupted Wzz1-mediated regulation of shorter O-Ag chains, providing the first evidence for direct Wzy–Wzz interaction. Mutagenesis studies identified functionally-important charged and aromatic TMS residues localized to either the interior vestibule or TMS bundles in a 3D homology model constructed for Wzx. Substrate-binding or energy-coupling roles were proposed for these residues, respectively. The Wzx interior was found to be cationic, consistent with translocation of anionic O-Ag subunits. To test these hypotheses, Wzx was overexpressed, purified, and reconstituted in proteoliposomes loaded with I−. Common transport coupling ions were introduced to “open” the protein and allow detection of I− flux via reconstituted Wzx. Extraliposomal changes in H+ induced I− flux, while Na+ addition had no effect, suggesting H+-dependent Wzx gating. Putative energy-coupling residue mutants demonstrated defective H+-dependent halide flux. Wzx also mediated H+ uptake as detected through fluorescence shifts from proteoliposomes loaded with pH-sensitive dye. Consequently, Wzx was proposed to function via H+-coupled antiport. In summary, this research has contributed structural and functional knowledge leading to novel mechanistic understandings for O-Ag biosynthesis in bacteria. / Bookmarks within the document have been provided for ease of access to a particular section in the body of the thesis. Each entry in the Table of Contents, List of Tables, and List of Figures has been "linked" to its respective position and as such can be clicked for direct access to the entry. Similarly, each in-text Figure or Table reference has been "linked" to its respective figure/table for direct access to the entry. / 1.) Canadian Institutes of Health Research (CIHR) Frederick Banting and Charles Best Canada Graduate Scholarship doctoral award, 2.) CIHR Michael Smith Foreign Study Award, 3.) Cystic Fibrosis Canada (CFC) doctoral studentship, 4.) University of Guelph Dean's Tri-Council Scholarship, 5.) Ontario Graduate Scholarship in Science and Technology, 6.) Operating grants to Dr. Joseph S. Lam from CIHR (MOP-14687) and CFC