The aqueous phase photo-oxidation of water soluble organic compounds (WSOC) extracted from α-pinene ozonolysis secondary organic aerosol (SOA) was investigated using high resolution time-of-flight chemical ionization mass spectrometry (CI-ToFMS). The results have shown that WSOC get more functionalized and fragmented as the reaction proceeds. The capabilities of three reagent ions, were assessed; specifically, (H2O)nH+ ionizes organic compounds with carbon oxidation state (OSC) ≤ 1.3, whereas CH3C(O)O- and I(H2O)n- ionize highly oxygenated organics with OSC up to 4, with I(H2O)n- showing more selectivity. The aqueous phase OH oxidation of cis-pinonic acid and tricarballylic acid (a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), recognized as a tracer of α-pinene SOA) were also studied. The respective rate constants at 301 K were measured to be 3.4(±0.5)×10^9 M^-1s^-1 at pH=2 and 3.1(±0.3)×10^8 M^-1s^-1 at pH=4.6. This work also illustrates possible aqueous phase mechanism for MBTCA formation from cis-pinonic oxidation.

The extensive agricultural usage of organohalogenated pesticides has raised many concerns about their potential hazards especially in the soil environment. Environmental metabolomics is an emerging field that investigates the changes in the metabolic profile of native organisms in their environment due to the presence of an environmental stressor. Research presented here explores the potential of Nuclear Magnetic Resonance (NMR)-based metabolomics to examine the sub-lethal exposure of the earthworm, Eisenia fetida to sub-lethal concentrations of organohalogenated pesticides. Various one-dimensional (1-D) and two dimensional (2-D) NMR techniques were compared in a contact filter paper test earthworm metabolomic study using endosulfan, a prevalent pesticide in the environment. The results determined that both the 1H Presaturation Utilizing Gradients and Echos (PURGE) and the 1H-13C Heteronuclear Single Quantum Coherence (HSQC) NMR techniques were most effective in discriminating and identifying significant metabolites in earthworms due to contaminant exposure. These two NMR techniques were further explored in another metabolomic study using various sub-lethal concentrations of endosulfan and an organofluorine pesticide, trifluralin to E. fetida. Principal component analysis (PCA) tests showed increasing separation between the exposed and unexposed earthworms as the concentrations for both contaminants increased. A neurotoxic mode of action (MOA) for endosulfan and a non-polar narcotic MOA for trifluralin were delineated as many significant metabolites, arising from exposure, were identified. The earthworm tissue extract is commonly used as the biological medium for metabolomic studies. However, many overlapping resonances are apparent in an earthworm tissue extract NMR spectrum due to the abundance of metabolites present. To mitigate this spectral overlap, the earthworm’s coelomic fluid (CF) was tested as a complementary biological medium to the tissue extract in an endosulfan exposure metabolomic study to identify additional metabolites of stress. Compared to tests on the tissue extract, a plethora of different metabolites were identified in the earthworm CF using 1-D PURGE and 2-D HSQC NMR techniques. In addition to the neurotoxic MOA identified previously, an apoptotic MOA was also postulated due to endosulfan exposure. This thesis also explored the application of 1-D and 2-D NMR techniques in a soil metabolomic study to understand the exposure of E. fetida to sub-lethal concentrations of endosulfan and its main degradation product, endosulfan sulfate. The earthworm’s CF and tissue extract were both analyzed to maximize the significant metabolites identified due to contaminant exposure. The PCA results identified similar toxicity for both organochlorine contaminants as the same separation, between exposed to the unexposed earthworms, were detected at various concentrations. Both neurotoxic and apopotic MOAs were observed as identical fluctuations of significant metabolites were found. This research demonstrates the potential of NMR-based metabolomics as a powerful environmental monitoring tool to understand sub-lethal organohalogenated pesticide exposure in soil using earthworms as living probes.

In urban areas, emissions of nitrogen oxide radicals (NOx ≡ NO + NO2) to the atmosphere from anthropogenic activities such as fossil fuel combustion contribute to poor air quality through the production of ozone and particulate matter. Soils are also a significant global source of NOx, but at downind forest environments the deposition of transported reactive nitrogen can be much more important than local emissions. Data from a government monitoring network in the Toronto area from 2000-2007 was used to explore the impact of long-term trends in NO2 and other ozone precursors on local ozone levels. Non-linear chemistry and the influence of meteorology explained why reductions in precursor levels during this period did not lead to significant improvements in ozone. Data from this network was also used to investigate the ability of a satellite-borne spectrometer to represent spatial patterns of ground-level NO2 in the same region. Selection biases, resulting from the need to discard satellite data on cloudy days, were shown to affect locations differently and were most severe at a receptor site. The sum of all reactive nitrogen oxides including NOx is known as NOy. A custom-built instrument for high precision and time resolution measurements of reactive nitrogen oxides was tested under various lab and field conditions, and used in field work where direct biosphere-atmosphere exchange of NOy was measured by eddy covariance above two comparable North American mixed forests (Haliburton Forest Wildlife Reserve and the University of Michigan Biological Station). While these forests were found to be small net sources of NOx, they were subject to elevated rates of NOy deposition overall, driven by the transport of polluted air from upwind source regions. Wet deposition measurements were used to show that dry deposition contributed a significant fraction of total deposition during the observation periods.

Mechanistic aspects of carbonaceous aerosol toxicity were examined with respect to the ability of particles to catalyse reactive oxygen species-generating redox cycling reactions. To investigate the role of secondary organic material, we examined two systems. In the first, two-stroke engine exhaust particles were found to increase their ability to catalyse redox cycling in the presence of a reducing agent, dithiothreitol (DTT), when the exhaust was exposed to ozone. This occurred through deposition of redox-active secondary organic aerosol (SOA) onto the particle that was ten times more redox active per microgram than the primary engine particle. In the second system, naphthalene SOA formed highly redox active particles. Activity was strongly correlated to the amount of the 1,4- and 1,2-naphthoquinone measured in the particle phase. However, these species and the newly quantified naphthalene oxidation product 5-hydroxy-1,4-naphthoquinone accounted for only 30% of the observed DTT decay from the particles. Gas-particle partitioning coefficients suggest 1,4- and 1,2-naphthoquinone are not strong contributors to ambient particle redox activity at 25°C. However, a large number of redox active species are unidentified. Some of these may be highly oxidised products of sufficiently low vapour pressure to be atmospherically relevant. DTT activity of diesel particles was found to be high per unit mass. The activity was found to be associated with the insoluble fraction as filtration of the particles nearly eliminated DTT decay. Neither methanol nor dichloromethane extracts of diesel particles exhibited redox activity, indicating that the redox active species are associated with the black carbon portion of the particles. Examination of particle concentration techniques found that use of water condensation to grow and concentrate particles introduced a large organic artefact to the particles. Experiments with concentrated inorganic particles suggest that the source of this artefact is from irreversible uptake of water-soluble volatile organic compounds. Overall, carbonaceous redox active species can be thought of as a continuum from small, water-soluble species to redox active functionalities on elemental carbon backbones. In addition to clearly defined, quantifiable species, future research may need to consider examining broader chemical classes or redox-active chemical functionalities to overcome the inherent complexity of these constituents.

The aqueous phase photo-oxidation of water soluble organic compounds (WSOC) extracted from α-pinene ozonolysis secondary organic aerosol (SOA) was investigated using high resolution time-of-flight chemical ionization mass spectrometry (CI-ToFMS). The results have shown that WSOC get more functionalized and fragmented as the reaction proceeds. The capabilities of three reagent ions, were assessed; specifically, (H2O)nH+ ionizes organic compounds with carbon oxidation state (OSC) ≤ 1.3, whereas CH3C(O)O- and I(H2O)n- ionize highly oxygenated organics with OSC up to 4, with I(H2O)n- showing more selectivity. The aqueous phase OH oxidation of cis-pinonic acid and tricarballylic acid (a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), recognized as a tracer of α-pinene SOA) were also studied. The respective rate constants at 301 K were measured to be 3.4(±0.5)×10^9 M^-1s^-1 at pH=2 and 3.1(±0.3)×10^8 M^-1s^-1 at pH=4.6. This work also illustrates possible aqueous phase mechanism for MBTCA formation from cis-pinonic oxidation.

Materials science today is a multidisciplinary effort comprising an accelerated convergence of diverse fields spanning the physical, applied, and engineering sciences. This diversity promises to deliver the next generation of advanced functional materials for a wide range of specific applications. In particular, the past decade has seen a growing interest in the development of nanoscale materials for sophisticated technologies. Aqueous colloidal microgels have emerged as a promising class of soft materials for multiple biotechnology applications. The amalgamation of physical, chemical and mechanical properties of microgels with optical properties of nanostructures in hybrid composite particles further enhances the capabilities of these materials. This work covers the general areas of responsive polymer microgels and their composites, and encompasses methods of fabricating microgel-based drug delivery systems for controlled and targeted therapeutic applications. The first part of this thesis is devoted to acquainting the reader with the fundamental aspects of the synthesis, functionalization and characteristic properties of stimulus-responsive microgels constructed from poly(N-isopropylacrylamide) (poly(NIPAm)) and other functional comonomers. In particular, the role of electrostatics on the swelling-deswelling transitions of polyampholyte microgels upon exposure to a range of environmental stimuli including pH, temperature, and salt concentration are discussed. The templated synthesis of bimetallic gold and silver nanoparticles in zwitterionic microgels is also described. The latter part of this thesis focuses on the rational development of microgel-based drug delivery systems for controlled and targeted drug release. Specifically, the development of a biofunctionalized, pH-responsive drug delivery system (DDS) is illustrated, and shown to effectively suppress cancer cells when loaded with an anticancer agent. In another chapter, the design of tailored hybrid particles that combine the thermal response of microgels with the light-sensitive properties of gold nanorods to create a DDS for photothermally-induced drug release is discussed. The photothermally-triggered volume transitions of hybrid microgels under physiological conditions are reported, and their suitability for the said application evaluated. In another component of this work, it is explicitly shown that electrostatic interactions were not needed to deposit gold nanorods on poly(NIPAm)-derived particles, thereby eliminating the need for incorporation of charged functional groups in the microgels that are otherwise responsible for large, undesirable shifts and broadening of the phase transition.

Doctor of Philosophy / Curriculum and Instruction Programs / Tweed R. Ross / John R. Staver / The purpose of this study was to research, develop and validate a one-semester course for the general education of university undergraduates in forensic chemical education. The course outline was developed using the research and development (R&D) methodology recommended by Gall, Borg, and Gall, (2003) and Dick and Carey, (2001) through a three step developmental cycle. Information was gathered and analyzed through review of literature and proof of concept interviews, laying the foundation for the framework of the course outline. A preliminary course outline was developed after a needs assessment showed need for such a course. Professors expert in the area of forensic science participated in the first field test of the course. Their feedback was recorded, and the course was revised for a main field test. Potential users of the guide served as readers for the main field test and offered more feedback to improve the course.

Master of Science / Food Science Institute - Animal Sciences and Industry / J. Scott Smith / The popularity of convenience foods and consumer awareness have indirectly increased the demand for novel and naturally occurring compounds that can delay oxidative deterioration and maintain nutritional quality of foods. Natural antioxidants from certain herbs and spices such as rosmarinic acid from rosemary, thymol from oregano, eugenol from clove, curcumin from turmeric are rich in polyphenolic compounds that provide long term oxidative stability as well as offer additional health benefits. High antioxidative capacity of herbs and spices phenolics could potentially substitute synthetic antioxidants such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), propyl gallate (PG), octyl gallate, and tert-butylated hydroquinone (TBHQ) in the food system. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are thermally unstable and decompose at higher temperatures. However, widely used cooking methods such as baking, frying, boiling, and roasting use high thermal temperature that can chemically degrade herbs and spices and diminish their antioxidative capacity, but they have been little studied. In this context, this review deals with the need of natural antioxidants, spices and herbs as natural antioxidants, their origin, chemical composition, pharmacological, and antioxidant properties. Moreover, the impact of temperature on total antioxidant capacity (TAC) of various herbs and spices such as cinnamon, clove, nutmeg, mace, oregano, rosemary, sage, and turmeric is highlighted. Different antioxidant assays are also studied and this approach revealed that there is a clear correlation between total phenolic content (TPC) and TAC of herbs and spices and specific phenolic compounds are responsible for the antioxidative capacity of particular herb and spice. These findings identified the optimum cooking temperature-time combination which results in the highest retention of antioxidative capacity and assures higher quality of food for the maintenance of human health.

Les hydrogels sont des matériaux aux propriétés modulables dont la dégradation peut être contrôlée. Du fait de leur biocompatibilité, ils peuvent être utilisés afin de protéger les médicaments labiles et ainsi favoriser l’administration de traitements médicaux, d’où l’intérêt croissant de développer ces matériaux. Depuis quelques années, ils font l’objet de nombreuses recherches, que ce soit en ingénierie tissulaire, détection de mouvement, régénération de tissus ou pour le relargage de médicaments. Ce projet de thèse porte sur la formation d’hydrogels à base d’α-cyclodextrine et de polyéthylène glycol 20K ainsi que sur l’étude de leur capacité de relargage de principes actifs. Ces composés ont la capacité de former des complexes d’inclusion, créant ainsi un collier de perle, appelés pseudopolyrotaxane. Ensuite, ils seront modifiés pour créer des hydrogels de polyrotaxanes grâce à l’ajout de groupement bloquants. Finalement, nous formerons des hydrogels à point de réticulations glissant après avoir relié deux polyrotaxanes par leur macrocycle. À l’aide d’études rhéologiques, nous avons montré une amélioration des propriétés mécaniques des hydrogels proportionnelle à l’apport de liaisons chimique. Les groupements bloquants permettent d’éviter la désinclusion tandis que les réticulations apportent un effet poulie, les rendant exceptionnellement élastique. Ces hypothèses sont validées par les études structurales. Et nos hydrogels se sont révélés non toxiques pour les cellules humaines et ces résultats confirment leur biocompatibilité. Les hydrogels de pseudopolyrotaxanes sont les plus écologiques et les plus appropriés pour une application locale cutanée. Les hydrogels de polyrotaxanes, plus stables, peuvent être utilisés pour des applications locales prolongées ou par injection. Cependant, nos hydrogels de polyrotaxanes réticulés devront être modifiés afin de permettre un relargage contrôlé, car leur extrême stabilité pourrait entraver leur dégradation lors d'une injection sous-cutanée malgré leurs propriétés mécaniques exceptionnelles. / Hydrogels are materials with tunable properties whose degradation can be controlled. Because of their biocompatibility, they can be used to protect labile drugs and thus facilitate the administration of medical treatments, hence the growing interest in developing these materials. In recent years, they have been the subject of numerous studies, whether in tissue engineering, motion sensing, tissue regeneration or drug delivery. This project focuses on the formation of hydrogels based on α-cyclodextrin and polyethylene glycol 20K and the study of their drug release capacity. These compounds can form inclusion complexes, forming a pearl necklace called pseudopolyrotaxane. They will then be modified to form polyrotaxane hydrogels by adding blocking groups. Finally, we will form hydrogels with sliding cross-linking points after linking two polyrotaxanes through their macrocycle. Through rheological studies, we have demonstrated an improvement in the mechanical properties of the hydrogels proportional to the introduction of chemical bonds. Blocking groups prevent desorption, while cross-linking provides a pulley effect, making them exceptionally elastic. These hypotheses are supported by structural studies. Our hydrogels have been shown to be non-toxic to human cells, confirming their biocompatibility. Pseudopolyrotaxane hydrogels are the most environmentally friendly and suitable for local cutaneous application. Polyrotaxane hydrogels are more stable and can be used for prolonged local applications or by injection. However, our cross-linked polyrotaxane hydrogels will need to be modified to allow controlled release, as their extreme stability could hinder their degradation during subcutaneous injection, despite their exceptional mechanical properties.

L’étude des polymorphes, soit des composés qui peuvent cristalliser avec plus d’une forme cristalline, est un centre d’intérêt pour nombreux domaines scientifiques. Dans certains cas, les variations structurales ont pour effet de causer de majeurs changements aux propriétés physicochimiques des composés, donnant la possibilité de préparer des matériaux possédant des caractéristiques précises pour une application donnée. Le domaine des explosifs est en continuelle évolution afin de combler les besoins militaires et civils. Des matériaux détenant un bon équilibre entre une haute performance énergétique et la sécurité sont recherchés. La 6-azidotétrazolo[5,1- a]phtalazine (ATPH) est une molécule riche en azote étroitement lié aux substances conçues comme explosifs. Dans le cadre de ce mémoire, le criblage polymorphique de l’ATPH entraine la découverte et l’isolation de six nouvelles formes solides de l’ATPH. Les motifs d’empilement à feuillets et à chevrons sont retrouvés dans l’ensemble des structures par des interactions polarisées N…N/C-H…N. Les polymorphes ont été caractérisés par IR, Raman, DSC, PXRD, SC-XRD et des études de stabilité relative en solution. Le caractère hautement polymorphique de l’ATPH est supporté par les résultats d’une étude computationnelle de prédiction des structures cristallines. / The study of polymorphs, or compounds that can crystallize in more than one crystal form, is a focus of interest for many scientific fields. In some cases, structural variations cause major changes in the physicochemical properties of the compounds, making it possible to prepare materials with specific characteristics for a given application. The development of explosive materials is a continuously evolving field for military and civilian purposes. Materials with a fine balance between high energy performance and safety are sought. 6-Azidotetrazolo[5,1-a]phthalazine (ATPH) is a nitrogen-rich molecule closely related to substances designed as explosives. In this dissertation, polymorphic screening of ATPH resulted in the discovery and isolation of six new solid forms of ATPH. Sheets and chevron stacking motifs directed by polarized C-N···N/C-H···N interactions were observed in all structures. The polymorphs were characterized by IR, Raman, DSC, PXRD, SC-XRD, and relative stability studies in solution. The highly polymorphic character of ATPH is consistent with the results of computational crystal structure prediction.