title: Fluorine-18 Tracer Studies of Inorganic and Organic Electrophilic Fluorinating Agents

contributor:
Schrobilgen, Gary J.
Chirakal, Raman V.
Chemistry

subject: fluorine, inorganic, organic, electrophilic, agents, spectroscopy, reaction, exchange

abstract:
 Fluorine-18 labelled F2, produced by the nuclear reaction, 18O(p,n)18F, and recovered from an oxygen-18 gas target, has been used to elucidate the mechanism for the formation of XeF+AsF6- from Xe, F2, and AsF5 under low temperature and dark conditions. Formation of XeF+AsF6- was confirmed by Raman spectroscopy. A method was designed to allow for the dilution of the 18F activity onto a pool of carrier 19F2 such that suitable quantities of low specific activity [18F]F2 could be produced for the mechanistic study of this reaction. Based on the 18F distributions within the products and unreacted [18F]F2 and AsF5, it was shown that an F2-AsF5 activated complex containing an electrophilic fluorine reacts with the weak electron donor, xenon gas, in a Lewis acid-base type reaction. The absence of random fluorine exchange within the activated complex indicated that a transient Fδ+ was responsible for the enhanced oxidizing ability of the F2-AsF5 complex, rather than the production of a formal "F+" or F· intermediate. Fluorine-18 investigations into the reaction of the F2-AsF5 activated complex with other possible electron donors have shown some 18F transfer with krypton gas. Attempts to establish the formation of KrF+ using 19F NMR spectroscopy have shown no evidence for the presence of the cation in the Kr/F2/AsF5 system. The systems Kr/F2/HF/SbF5 and OF2/F2/AsF5 were not seen to undergo a reaction.

 The results of such sensitive radiotracer experiments required a complete analysis of the composition of the target gas delivered from the 18O(p,n)18F oxygen gas target; the presence of reactive agents other than [18F]F2 could affect the distribution of activities in reaction mixtures. Oxygen difluoride, which was suspected as a possible side product of the double bombardment method, was identified as a constituent of the target gas by 19F NMR characterization. An analysis of the effect of the variation of irradiation parameters has concluded that the quantity of [18F]OF2 activity is independent of the production irradiation parameters and is most likely a consequence of the presence of small amounts of O2 within the target during the recovery irradiation.

 The application of CsSO4F as an electrophilic fluorinating agent has provided preliminary evidence for the flourination of biologically active aromatic amino acids. Cesium fluoroxysulphate was found to react with 3,4-dihydroxyphenylalanine (L-Dopa) in an CH3CN solution containing BF3 to produce a mixture 2-, 5-, and 6-fluoro-L-dopa. Fluorine-19 NMR spectroscopy was used to confirm the presence of the 2-, 5-, and 6-fluoro-isomers of fluorodopa in the reaction mixture.

abstract: Thesis

abstract: Master of Science (MSc)


title: Synthesis of [1-3H]-Geranylgeranyl Pyrophosphate and its Incubation with Taxus x Media Densiformis

contributor:
Harrison, Paul
Chemistry

subject: synthesis, pyrophosphate, incubation, densiformis, taxus x media, species, diterpenoids

abstract:
 Recently, the discovery that taxol (2), a highly modified diterpenoid available from Taxus species, possesses anticancer activity has attracted considerable interest. The synthesis of [1-3H]-geranylgeranyl pyrophosphate(1b), a labelled form of the precursor to the diterpenoids(1a), and its incubation with a cell-free enzyme preparation from Taxus x media densiformis, a species of yew tree, were investigated.

 The investigation into the biosynthesis of taxol(2) was to be accomplished by monitoring the enzymatic transformations of (1b). The synthesis of 1b was accomplished via a convergent method using geraniol, a ten carbon compound, as the starting material. Essentially two molecules of geraniol were chemically manipulated and condensed to give geranyl geraniol which was oxidized to the corresponding aldehyde and then reduced using sodium borotritide. The radioactive alcohol was subsequently converted to the pyrophosphate (1b) using standard methodology. Cell-free extracts of Taxus x media densiformis were prepared and incubated with [1-3H]-GGPP (1b), the intermediates were extracted, and then analyzed by scintillation counting and radioactive gas chromatography. Identification of these labelled intermediates was attempted in order to provide information about the biosynthesis of 2. (Diagram included in thesis)

abstract: Thesis

abstract: Master of Science (MSc)


title: Tandem Mass Spectrometry and Computational Chemistry of Elusive Organic Ions and Neutrals in the Gas Phase

contributor:
Terlouw, Johan K.
Chemistry

subject: mass, spectrometry, computational, elusive, organic, ions, neutral, gas, phase, molecules, energy

abstract:
 Small nitrogen or silicon containing molecules and their ionized counterparts have attracted a great deal of attention from both experimentalists and theoreticians. This is because such species may play an important role in interstellar chemistry. Small nitrogen containing heterocyclic molecules and ions are of biological importance and are of increasing interest to chemists and biochemists. Therefore, studying the chemistry of such species in the gas phase as solitary ions and neutrals is of considerable importance.

 The ions studied in this thesis were generated in the rarefied gas phase of the mass spectrometer by (dissociative) electron ionization of selected precursor molecules. The characterization of their structure and reactivity was realized using a variety of tandem mass spectrometry based techniques. These include metastable ion spectra to probe the dissociation chemistry of the low energy ions and (multiple) collision experiments to establish the structure (atom connectivity) of the stable ions. The technique of neutralization-reionization mass spectrometry (NRMS) was used to probe the structure and stability of the neutral counterparts of the ions. The results of theoretical calculations involving the CBS-QB3 model chemistry formed an essential component in the interpretation of the experimental findings.

 The above approach was used to study various isomers of the CH2N2•+ family of ions, in particular the elusive carbodiimide ion HN=C=NH•+. Unlike other isomers including ionized cyanamide H2N-C≡N•+ and nitrilimine HC=N=NH•+, the carbodiimide ion could only be identified by a strategy that involved the use of the technique of collision-induced dissociative ionization (CIDI) mass spectrometry. Guided by the results of the theoretical calculations, the carbodiimide ion, the global minimum on the CH2N2•+ potential energy surface, could also be generated by the molecule-assisted isomerization of its 1,3-H shift isomer H2N-C≡N•+. This occurs through an ion-molecule interaction with a single molecule of H2O under conditions of chemical ionization : a process termed proton-transport catalysis.

 The amino-substituted carbodiimide ion, H2N-N=C=NH•+, and nine more isomers have all been calculated to be minima on the potential energy surface of the CH3N3•+ family of ions. Four of these, viz. the aminocarbodiimide ion, the aminonitrilimine ion, H2N-C=N=NH•+, the cyclic C-aminoisodiazirine ion, and the ionized biradical, H2N-N=C(H)=N•+, were generated and characterized by tandem mass spectrometry as stable species in the gas phase. Neutralization-reionization experiments show, in agreement with the CBS-QB3 computational results, that aminocarbodiimide and aminonitrilimine are stable species in the gas phase.

 Next, the α-distonic ions of a number of heterocyclic nitrogen-containing compounds including pyrazole, pyridazine and aminopyrazine, were characterized and differentiated by tandem mass spectrometry. The stabilities of the neutral counterparts of the ylid ions and their conventional isomers were probed by neutralization-reionization experiments. From these experiments, it follows that the ylid ions have stable neutral counterparts, as predicted by the theoretical calculations.

 The final component of this work deals with the chemistry of a silicon containing species of potential interest in interstellar chemistry. The reactions of protonated silicic acid, Si(OH)3+, and the mechanisms of these reactions were studied using tandem mass spectrometric experiments and CBS-QB3 model chemistry. The low energy (metastable) ions of Si(OH)3+ dissociate by loss of H2O and SiO2 to form O=SiOH+ and H3O+ ions. Neutralization-reionization experiments show that Si(OH)3• is a stable species in the rarefied gas phase.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Preparation of Intermediates in the Synthesis of (1R,7'R)-Decumbensine and (13R,14R)-Ophiocarpine

contributor:
MacLean, D. B.
Chemistry

subject: preparation, intermediates, synthesis, decumbensine, ophiocarpine

abstract:
 The synthesis of 2-ethoxycarbonyl-1-hydroxymethyl-1,2,3,4-tetrahydro-6,7-methylenedioxyisoquinoline 117 and 2-acetyl-1,2,3,4-tetrahydro-6,7-methylenedioxyisoquinoline-1-carboxaldehyde 126 are described. These compounds are potentially useful intermediates for the asymmetric synthesis of two tetrahydroisoquinoline alkaloids, (1R,7'R)-decumbensine and (13R,14R)-ophiocarpine. Decumbensine is a simple 1-benzyl-1,2,3,4-tetrahydroisoquinoline alkaloid having a hydroxyl group at the carbon atom adjacent to C-1 of the isoquinoline ring. Ophiocarpine belongs to the tetrahydroprotoberberine group of isoquinoline alkaloids and has a hydroxyl group in the same relative position in its ring system as that found in decumbensine.

 The first synthesis led to a racemic intermediate which would require resolution before proceeding with the asymmetric synthesis. The second synthesis led directly to an optically active aldehyde and would appear to be the more satisfactory route.

 A procedure for the preparation of 3-benzyloxy-4-methoxy bromobenzene is also described. This compound, after halogen-metal exchange, would be used to introduce the second aromatic ring in the ophiocarpine synthesis.

 The literature on asymmetric synthesis of tetrahydroisoquinoline alkaloids has been reviewed in the introduction. (Diagrams included in thesis)

abstract: Thesis

abstract: Master of Science (MSc)


title: Nature and Origin of Foliation and Lineation in Porphyry, Killarney, Ontario

contributor:
Clifford, P. M.
Geology

subject: nature, origin, foliation, lineation, granite, porphyry, rocks, deformation

abstract:
 The Killarney Igneous Complex, composed of an intrusive granite and a hypabyssal or extrusive porphyry was implaced near and at the surface in the general locality of Killarney, Ontario. The crystallization age of the intrusive portion of the complex is approximately 1740 million years. These rocks have experienced deformation by forces which in some instances produced complicated shearing motions. Mesoscopic samples show a foliation and a lineation supporting a history of deformation. The foliation is clearly the more visible fabric and is interpreted as a plane of flattening.

 Kinematic indicators, specifically asymmetric pressure shadow wings, are present within the rocks; however the patterns are too complicated to interpret by a simple sense of shear. The geometry of these kinematic indicators does suggest an active plane of foliation.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Ester Azines from Reactions of Carbenes with Oxadiazolines

subject: ester, azines, reactions, carbenes, oxadiazolines, synthesized, thermolysis, carbonyl, compounds, equilibration

abstract:
 A series of 2-substituted Δ^3-1,3,4-oxadiazolines (i) were synthesized by oxidation of the corresponding hydrazones with lead-tetraacetate in alcohol, eq A. (See Diagram A in Thesis)

 These oxadiazolines, upon thermolysis, generated carbonyl ylide intermediates (ii). These ylides are known to undergo fragmentation into carbenes and carbonyl compounds, eq B. (See Diagram B in Thesis)

 A new series of products were found from the thermolysis of these types of oxadiazolines, ester azines iv and v. A possible mechanism for the formation of these ester azines involves carbene attack on the oxadiazoline to give an azomethine imine intermediate (iii) which can subsequently rearrange to give the azines and carbonyl compounds, eq C. (See Diagram C in Thesis)

 This mechanism is supported by the observation that the overall yields of ester azines rise with increasing initial concentration of oxadiazoline whereas the yield of propene, a rearrangement product of
dimethyl carbene, falls with increasing initial concentration of oxadiazoline.

 The ester azines (R=CH3, CH2CH3 and CH(CH3)2) were found to be uniconfigurational and the E-configuration was assigned to ester azine iv and the E,E-configuration was assigned to ester azine v. Ester azines (R=C(CH3)3) were found to exist as configurational isomers. Equilibration studies were carried out on these ester azines and the thermodynamic
parameters ΔG°, ΔH° and ΔS° were found for equilibration shown in eq D. (See Diagram D in Thesis)

 Changing the R' substituent of i to OCH2CCl3 or OCH2CF3 did not
stop fragmentation of the derived ylide. Ester azines were found from the thermolysis of these oxadiazolines also. They were found to be uniconfigurational and were assigned the E-configuration.

abstract: Thesis

abstract: Master of Science (MSc)


title: A MIXED-METHOD ANALYSIS OF SENSE OF PLACE AND MENTAL WELLBEING OF VISIBLE MINORITY IMMIGRANTS

contributor:
NEWBOLD, BRUCE
Geography and Earth Sciences

subject: SENSE OF PLACE, MENTAL WELLBEING, IMMIGRANTS

abstract: Employing an expanded meaning of the concept of sense of place within Health Geography, this thesis explores the relationship between sense of place and mental wellbeing of immigrants. The concept of sense of place demonstrates the importance of specific places for socioeconomic and health impacts on individuals and groups in their societies. While research has explored immigrants’ sense of place, few studies have attempted to explore visible minority’s perceptions of place and its influence on wellbeing. Using qualitative and quantitative techniques, this thesis explores the perceptions and experiences of place amongst Ghanaian and Somali immigrants in Hamilton, Ontario, Canada. First, we explore key informants’ revelations on immigrants’ sense of place and mental wellness in Hamilton, Ontario. Findings provide insight into the role of policies that affect determinants of health amongst immigrants. Second, we examine the effects of self-perceived mental wellness, socioeconomic and demographic variables on sense of place amongst Ghanaian and Somali immigrants living in Hamilton, based on an analysis of a survey questionnaire (n=236). Findings highlight a positive relationship between sense of place and mental wellness. Third, using descriptive and multivariate regression methods, we focus on factors that predict African immigrants’ life satisfaction in Canada. We examine sociodemographic, economic and health-related factors that predict life satisfaction amongst African immigrants, specifically Ghanaian and Somali immigrants. We find that immigrant settlement workers and agencies would be better able to meet the needs of immigrants if they are conscious of the factors that would empower immigrants to cope with life stresses. We suggest a reduction of stress by helping individuals and families identify sources of support, providing jobs, affordable housing, language interpretation and training. Lastly, we explore specific places, religious sites and their relationship to health and wellbeing for immigrants. Specifically, we explore churches and mosques where Ghanaian and Somali immigrants worship. We find that   places of worship are significant for physical health, social, emotional, spiritual, mental, and general quality of life amongst immigrants. The thesis is highly relevant in the current Canadian policy context, which includes contribution to the understanding of the determinants of health and integration of immigrants, providing insights into the concepts of sense of place and mental wellbeing, and broadening our understanding of African immigrants’ integration. Overall, this thesis develops a better understanding of immigrants’ settlement and integration, and further contributes to the broader immigration literature.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Degenerate and Nondegenerate Rearrangements in 8,8-Dimethylbenzohomotropylium Cations

contributor:
Childs, R. F.
Chemistry

subject: degenerate, cations, rearrangement, homotropylium, stability, isomers, methyl, thermal

abstract:
 Investigations on the stability and reactions of various isomers of the benzohomotropylium/bridged [11]-annulene system are presented in this thesis. As 1,6-methano-[11]-annulenium cations are isomeric with benzohomotropylium cations in principle it is possible for these systems to be interconverted by a circumambulatory migration of the 'bridging' methano group. If this reaction were to proceed to equilibrium it would allow the examination of the thermodynamic stability of the various isomers.

 Homotropylium cations with two methyl groups at C8 are known to undergo facile circumambulatory rearrangements. Thus in this work the 1-hydroxy 8,8-dimethyl-2,3-benzohomotropylium and 1-hydroxy 8,8-dimethyl-4,5-benzohomotropylium cations have been prepared by protonation of the corresponding 2,3- and 4,5- benzohomotropones in FSO3H. On the basis of their 1H NMR spectra it is concluded that they can properly be regarded as homoaromatic cations. The thermal isomerizations of these cations have been studied in detail. The thermal isomerization of these cations led to the formation of a series of products but does not yield the corresponding [11]-annulenium isomer. In addition the barriers to ring inversion in these cations were found to be much lower than those of other homotropylium cations. This suggests that the former cations have a very open structure. Besides this experimental approach, the relative stability of these isomers has been explored using MNDO calculations. The calculated heats of formation (ΔHf) showed that the 1-benzohomotropylium cation is more stable than the corresponding [11]-annulenium ion by 21 kcal/mol.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Synthesis and Properties of Three New Network Polymers Studied by Calorimetric, Dielectric and Mechanical Relaxation Methods

contributor:
Johari, G. P.
Materials Science and Engineering

subject: synthesis, properties, network, polymers, calorimetric, dielectric, mechanical, relaxation, polymerization

abstract:
 This thesis is based on the studies of cross-linked network polymerization by
measurements of dielectric permittivity and a study of the polymers formed by dynamic
mechanical analysis. The network polymers are formed by reacting a trifunctional epoxy
with three primary amines, namely, aniline, 3-chloroaniline and 4-chloroaniline. The
manner in which the dielectric permittivity changes on polymerization was followed from
the monomeric to the ultimately polymeric state, and the relaxation time and the
distribution of reaction times was followed with reaction time. Isothermal measurements
of the heat evolved during the reaction led to a determination of the number of covalent
bonds formed at any instant of reaction time, thus the dielectric relaxation time was
related to the number of covalent bonds formed during polymerization. The relaxation
time increased progressively more rapidly with the increase in the number of covalent
bonds formed under isothermal conditions as the reaction progressed towards completion.
As the number of covalent bonds increased, a high-frequency, or low-temperature, relaxation process emerged. This was observed for both the time-variant (fixed frequency) and time-invariant (dielectric spectra) dielectric data.

 The extent of reaction at the gelation time deduced from the irreversible decrease in the dc conductivity on polymerization was 50% lower than anticipated from Flory-Stockmayer theory, but, the extent of reaction at the point of singularity agreed with the theory. As polymerization reactions occurred, both the static and high-frequency dielectric permittivities decreased with time. Data simulated for the dielectric behaviour for a fixed frequency during the course of polymerization were analyzed to confirm that the two analysis procedures (time-invariant and time-variant) yield the same parameters within 2-3%.

 The three, new, network polymers thus produced had unrelaxed and relaxed moduli that were in the ranges of 1.35-1.51GPa and 6.6-10.6MPa, respectively. GU of the three polymers decreased with increasing temperature and GR increased. The former effect has been attributed to mainly a decrease in the GR of the low-temperature, or high-frequency, β-relaxation process, and the latter to the increase in the temperature, and consequently, the increase in the entropy, as discussed in the entropy theories of the rubber modulus. The spectrum of the shear modulus cannot be superposed by shifting the spectra along the frequency scale alone. The three reasons discussed are; (1) GU and GR change with temperature, therefore the spectra differ in magnitude for each measurement temperature, (2) the presence of a temperature-dependent, frequency-independent background loss changes the magnitude of tan∅ with the temperature, and (3) the influence of secondary-, β-, or Johari-Goldstein relaxations causes deviations in the shape of the spectrum such that they cannot be superposed. It was determined that none of the three effects described contribute significantly to the changes in the isothermal spectra, and hence, the principle of the time-temperature superposition does not apply to the three polymers in this study. The three polymers produced have a mechanical loss peak at room temperature that is attributed to the β-relaxation process and whose magnitude is greater than that of polycarbonates. This suggests that the three new polymers produced here can absorb more energy at room temperature than the polycarbonates.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: The Coupling of Synthetic and Biological Polymers: Silicone - Starch Composites

contributor:
Brook, M. A.
Chemistry

subject: coupling, synthetic, biological, polymers, silicone, composites

abstract:
 This thesis presents a study of the compatiblization of a hydrophobic, synthetic
polymer, polydimethylsiloxane (PDMS) and a hydrophilic biopolymer, starch. The Diels-
Alder adduct of cyclopentadiene and maleic anhydride, bicyclo[2.2.1]hept-5-ene-2,3-
dicarboxylic-anhydride, (1), was hydrosilylated with hydride- terminated PDMS to yield
α,ω-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic-anhydride-polydimethylsiloxane, (4) having
an average molecular weight of 750 g mol^-1. This was then reacted with starch using
dimethylaminopyridine as a catalyst in a dimethylsulfoxide medium at 80°C to yield a
silicone-starch graft copolymer having a γ-carboxylic-ester linkage.

 In order to study the influences of the quantity of hydrophobic and hydrophilic components, a series of composites were synthesized varying the starch and silicone stoichiometry (series-1).

 In order to study the influence of the molecular weight of the silicone, 4 was
redistributed with octamethylcyclotetrasiloxane (D4) via cationic polymerization to yield
higher molecular weight derivatives. The products were 7 (1500 g mol^-1) and 8 (9000 g
mol^-1). These were reacted with starch to give a series of composites for each molecular
weight of the functionalized silicone.

 Spectroscopic and physical properties were analyzed for developing trends.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Mechanistic Study of Alcohol Addition to 1,1-Diphenylsilene

contributor:
Leigh, William J.
Chemistry

subject: mechanistic, alcohol, addition, diphenylsilene, photochemistry, reaction, transient, isotope

abstract: The photochemistry of 1,1-diphenylsilacyclobutane has been studied by steady-state and nanosecond laser flash photolysis (NLFP) techniques in order to investigate the mechanism of reaction of a transient silene with alcohols. NLFP of 1,1-diphenylsilacyclobutane (I) in acetonitrile solution at 325 nm results in the formation of 1,1-diphenylsilene (II) derived from excited-state [2+2]-cycloreversion of the silacyclobutane. The transient has a lifetime of 100 ns - 1.2 μS in acetonitrile solution at room temperature, depending on the presence of water in the solvent. Steady-state photolysis in the presence of various σ-bonded nucleophiles such as methanol results in the generation of a single product in each case, consistent with addition of the nucleophile to the silene (II). Absolute rate constants (kq) have been determined by NLFP techniques for reactions of the silene with water, methanol, ethanol, tert-butyl alcohol, 2-propanol, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, and glacial acetic acid. The rate constants (kq) illustrate the following characteristics: linear quenching plots characteristic of second order kinetics, observation of small but detectable deuterium kinetic isotope effects, and an inverse Arrhenius temperature dependence. Two possible mechanisms will be discussed based on these results. (See Mechanisms in Thesis)

abstract: Thesis

abstract: Master of Science (MSc)


title: Methacrylic Copolymers for Controlled Phase Separation and Complex Coacervation

contributor:
Stöver, Harald D. H.
Chemistry

subject: complex, coacervates, methacrylic, copolymers, synthetic, phase

abstract:
 It is well known that complex coacervates can be prepared by combining aqueous solutions of oppositely charged biopolymers, such as gelatin and gum arabic. There are few examples of synthetic polyelectrolytes that produce complex coacervates, however. Two series of anionic copolymers capable of forming complex coacervates with branched polyethylenimine (PEI) in water have been prepared. One series consists of binary copolymers containing methacrylic acid (MAA) and poly(ethylene glycol) monomethyl ether monomethacrylate (PEGMA) in molar ratios ranging from 20:80 to 80:20, as well as the two homopolymers, poly(MAA) and poly(PEGMA). Another series contains an equimolar amount of MAA and PEGMA, together with between one and ten percent of a third, hydrophobic monomer, butyl methacrylate (BMA).

 Both binary and ternary copolymers show lower critical solution temperatures, LCST's, ranging from 60.8°C to 1.5°C depending on composition. Furthermore, complex coacervation occurs upon addition of aqueous PEI to aqueous solutions of these copolymers. The percent volume of the liquid coacervate phase is independent of copolymer composition. However, with increasing MAA to PEGMA ratio in the binary copolymer, the concentration of the coacervate increases, reflecting an increased coacervation efficiency. The coacervate composition was not significantly affected by the BMA in the ternary copolymer series.

abstract: Thesis

abstract: Master of Science (MSc)


title: Polytrichlorosilylstyrenes: Exploiting the β-Effect for Polymer Synthesis

subject: polymer, synthesis, polytrichlororsilylstyrenes, silicon-carbon, bond, reactions, catalyst

abstract:
 Trimethylsilylstyrenes undergo protiodesilylation (Scheme 1, path A), via the β-silyl carbonium ion under acidic conditions. In contrast, the corresponding trichlorosilyl substituted compound was found to undergo an oligomerization reaction (Scheme 1, path B) with triflic acid as the catalyst. (See Diagram in Thesis)

 The β-effect [(σ-p)π overlap] may play a significant role in the weakening of the silicon-carbon bond and thus promote the cleavage process, as is observed in scheme 1, path A. Introduction of electronegative chloro groups on silicon weakens the β-effect and hence the silyl leaving group ability, resulting in oligomerization of the styrene (Scheme 1, path B).

 In this oligomerization reaction, chain termination by an internal Friedel-Crafts reaction competes with the chain propagation. As a result, indane terminated low moldecular weight oligomers are formed. The case is similar to β-methyldichlorosilylstyrene, with the only difference that here ca. 20% desilylation has occured, again reflecting the fact that subtle changes in the β-effect acan influence the course of electrophilic reactions.

abstract: Thesis

abstract: Master of Science (MSc)


title: Connecting Core Concepts with Everyday Chemistry

contributor:
Blizzard, A. C.
Humphreys, D. A.

subject: connecting, core, concepts, chemistry, everyday, theory, applications

abstract:
 The rationale for this project is based on the recognition that chemistry courses tend to be taught too much from a theoretical standpoint, with little reference to everyday life. This is one of the reasons that a majority of students think that chemistry is difficult, boring, tedious, and uninteresting (Worthy, 1982). If they have the choice, many students would rather not take a chemistry course, and if they do, it will probably be their last course in Chemistry.

 It is the intent of the Ontario Curriculum Guidelines to provide some science-technology-society connections. The aim of this project is to provide supplemental science-technology society connections, and selected concrete examples of practical, everyday chemistry for teachers, so that they may enrich their classes, motivate their students, and put theory into an appropriate context. If classes are more interesting and relevant to the world of the students, then more students could be motivated to take chemistry courses and consider continuing to more advanced classes. A second purpose for this project is to stimulate a typical non-science student's interest in chemistry and science. It is even more necessary to motivate these students by providing interesting connections with the real world and suitable applications of theory and principles. These connections with the real world are important for such students, so that they will be better able to make informed decisions as scientifically literate citizens, managers, or politicians, not only for themselves, but for the benefit of society as a whole.

 To accomplish the aims of this project, two or three short hand-outs of practical everyday chemistry were prepared for each of the core topics in the Grade 11 (SCH 3A) and Chemistry OAC (SCH OA) courses. A few of the examples included Dental Chemistry, Culinary Chemistry, Insect Pheromones, and Teflon.

 Results of the survey taken from chemistry teachers showed that these hand-outs would better motivate students to study chemistry. Teachers think it is useful for their classes. They would like a compilation of these examples, if one were to be made available.

abstract: Thesis

abstract: Master of Science (Teaching)


title: The Effects of Eutrophication on Reef Health; A Study in Zanzibar, Tanzania

contributor:
Risk, M. J.
Geology

subject: Eutrophication, reef, health, sewage, discharge, anthropogenic, Zanzibar, island, species, coral, mortality

abstract:
 A study of two shallow fringing reefs off the coast of Zanzibar Island was conducted. The study site was Grave Island, 1 km off the shore of Zanzibar town. The comparison site was Chumbe Island, 10 km upcurrent of the town, adjacent a less densely inhabitated coast. The major anthropogenic stress on these reefs could be considered nutrient loading from sewage discharge.

 Studies of the sea urchin Diadema setosum, indicated mean densities at Grave Island of 6.4 urchins/m^2 and 1.2 urchins/m^2 at Chumbe Island. Urchin densities comparable to those at Grave Island have been related to overfishing and reduced coral recruitment. Coral associate densities were also considered with a mean density of 87/m^2 at Grave Island and 31/m^2 at Chumbe Island. High coral associate densities have been linked to structurally and physiologically weakened coral.

 Transect studies were conducted and suggested there were significantly reduced coral cover and reduced amounts of live coral at Grave Island (cf Chumbe Island). As well, coral species diversity was significantly lower at Grave Island than at Chumbe Island. Lowered species diversity suggests an unstable community structure, and reduced coral cover may indicate a faltering reef.

 Stable Isotope studies were conducted on tissue samples from both sites. They showed no significant difference.

 This study reflects the poor health of Grave Island. The high abundance of urchins and filter feeders, combined with reduced coral cover and diversity, suggest high nutrient loading on these reefs. The high abundance of urchins and associates also suggest coral mortality will be high and recruitment low. If these trends continue, it is unlikely the reef at Grave Island will be able to survive.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Dioxycarbenes and 3,3-Dioxyvinylcarbenes in the Synthesis of Novel Heterocycles

contributor:
Warkentin, J.
Chemistry

subject: carbocyclic, heterocycles, novel, dioxycarbenes, synthesis, organic, bond

abstract:
 Carbocyclic and heterocyclic compounds are ubiquitous in nature. Therefore, the discovery and development of new ring forming reactions are of paramount interest to synthetic organic chemists. Recently, the intramolecular cyclization of reactive intermediates, such as anions, cations, and radicals have provided a number of new methods by which known and novel ring systems can be constructed. Cyclizations involving tandem, or multiple sequences have gained considerable popularity due to their high overall efficiency and remarkable speed by which these processes can yield complex polycyclic ring systems.

 Carbenes are another interesting class of reactive intermediates which undergo characteristic reactions. The cyclization reactions of carbenes have not been studied to a significant extent. In particular, the work described in this thesis outlines the only study of the intramolecular cyclization of dioxycarbenes onto a tethered alkyne moiety.

 The first section of this dissertation details the development of a convenient new class of thermal dioxycarbene precursors, dioxyoxadiazolines I, which display many significant advantages over previously used sources of dioxycarbenes ll. (See Diagram in Thesis)

 The second section of this dissertation details the use of dioxyoxadiazolines possessing a tethered triple bond for the thermal generation of dioxycarbenes III which are capable of intramolecular cyclization. It was found that the cyclization of a dioxycarbene onto a tethered triple bond results in the regioselective generation, of another reactive intermediate, a 3,3-dioxyvinylcarbene (IV or V, depending on the nature of R'), which can undergo a number of interesting intermolecular reactions. This approach leads to the rapid construction of some interesting and rather complex polycyclic heterocyles which are, in many cases, obtained with high regioselectivity and sometimes even high stereoselectivity. (See Diagram in Thesis)

 The results described in this thesis mark the discovery and development of a new synthetic methodology which may, by appropriate choice of the starting material, provide a valuable tool for the rapid and selective synthesis of a number of heterocyclic ring systems.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Synthesis of Heterocycles Via Free Radical Cyclization

subject: synthesis, heterocycles, cyclization, free, radical, abstraction

abstract: Aryl radical ring closures onto the azo functional group were investigated. A series of ortho-substituted aryl radicals (83a-f) have been generated by bromine abstraction from the corresponding 1-(orthobromophenyl)-1-methoxy-azoethanes (82a-f) by tributyltin radicals. The radicals generated underwent cyclization in the 5-endo sense, to ultimately afford the substituted indazoles (86a-f). There was also some evidence for cyclization to the other azo nitrogen (closure in the 4-exo sense) to form a 4-membered ring. The aryl radical also underwent hydrogen atom abstraction from tributyltin hydride in competition with cyclization. Since the rate constant for hydrogen atom abstraction from tributyltin hydride by aryl radicals is known, this makes it possible to estimate the rate constants for cyclization throughout the series.

abstract: Thesis

abstract: Master of Science (MSc)


title: Preliminary Investigations of CaCO3 Nucleation in Precipitation Reactions from Quasi-Homogeneous Solution

contributor:
Hileman Jr., O. E.
Chemistry

subject: preliminary, investigations, nucleation, precipitation, reactions, solution, calcium, carbonate, anion

abstract:
 An analysis of reported and theoretical methods of precipitating calcium carbonate from aqueous solution is presented, with emphasis on methods that generate the anion in the presence of Ca(++) ion.

 A new CaCO3 precipitation method referred to as precipitation from quasi-homogeneous solution and suitable for digital processor control is developed. This technique is then used to investigate the effects of ionic strength and Mg(++) ion on calcium carbonate nucleation.

 A minicomputer based interactive information system, capable of automatic data logging and processing of experimental results in studies using processor controlled precipitation of CaCO3 from quasi-homogeneous solution, is implemented and tested.

abstract: Thesis

abstract: Master of Science (MSc)


title: Chromium Complexes of Benzylic Cations: A Synthetic, High Field NMR Spectroscopic and EHMO Study

contributor:
McGlinchey, M. J.
Chemistry

subject: chromium, complexes, benzylic, cations, synthetic, NMR, spectroscopic, EHMO, study, temperature

abstract:
 Treatment of chromium hexacarbonyl with a series of benzyl alcohols yields the corresponding (R-C6H4CH2OH)Cr(CO)3 complexes, where R = 3-methoxy, 3-methyl, 4-methoxy or 4-methyl. These complexes were characterized by NMR spectroscopy.

 Protonation of the tricarbonylchromium alcohols with CF3SO3H at low temperature yields a benzyl cation complex which can be isolated and examined by variable-temperature 13C NMR spectroscopy. The spectra show a splitting of the carbonyl carbons at low temperature, providing evidence of electronically restricted rotation of the tripodal ligand. Evaluation of the simulated spectra provides the rotational barrier for this dynamic process. These results are rationalized by means of EHMO calculations.

 Evidence suggests tripodal rotation was also electronically hindered in the analogous fulvene complexes. Variable-temperature 13C NMR spectra of (6,6-Diphenylfulvene)Cr(CO)3 and (6-Methyl-6-phenylfulvene)Cr(CO)3 show respective 2:1 and 1:1:1 splitting of the carbonyl carbons a low temperature. Barriers of 8.3 kcal/mol and 8.8 kcal/mol were obtained by spectral simulation and were explained by using EHMO calculations.

 The calculated rotational barrier for the [α-(C5H5CH2)Cr(CO)2NO]+ cation suggests that NMR spectral evidence for hindered rotation may be difficult to obtain.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Room Pressure Spinelloid Phases of the NiGa2O4 - Ni2SiO4 System

subject: room, pressure, spinelloid, phases, temperature, nickel, crystal, structures

abstract: The ternary oxide system NiO - Ga2O3 - SiO2 has been studied in the temperature range 1400-1550°C at room pressure. Three phases, corresponding to the spinelloid phases I, II, and V, have been identified on the Ni2GaO4 (spinel) - Ni2SiO4 (olivine) join. These room-pressure phases are isostructural with the high-pressure spinelloid phases of the nickel aluminosilicate system. Single crystals of all three phases have been grown from a silica-rich melt and their crystal structures have been determined by X-ray diffraction. The structure refinements have revealed a strong ordering of the Ga and Si atoms on the tetrahedral sites of all three phases, as well as a clear correlation between spinelloid structure-type and composition. This correlation accounts for the increase in Ni2SiO4 content across the series spinel - phase V - phase I - phase II.

abstract: Thesis

abstract: Master of Science (MSc)


title: Fatigue Behaviour of Forged Ti-6Al-4V Made From Blended Element Powder Metallurgy

contributor:
Zurob, Hatem
Materials Science and Engineering

subject:
titanium
Ti-6Al-4V
powder
blended element
fatigue
porosity
forging
digital image correlation

abstract:
A detailed metallurgical analysis was conducted to correlate microstructure to axial strain-controlled high cycle fatigue of Ti-6Al-4V forgings made from cold isostatic pressed and sintered preforms of blended element powder metallurgy (BEPM) incorporating hydrogenated titanium. Analysis included fractographic examination by SEM, microstructure examination by optical microscopy, texture examination via EBSD, chemical analysis and fatigue strain mapping via digital image correlation (DIC). From a literature review and observations of findings, factors that were of primary concern were: maximum pore diameter, primary α volume fraction, primary α width, primary α particle count, oxygen equivalency (OE) and texture of the α phase.
The primary α volume fraction was found to have the single most influential effect on fatigue, whereby decreasing volume fraction increased fatigue life. Using statistical analysis, multivariable regression analyses were performed to evaluate combinations of predictors on fatigue life. The resulting outcome of volume fraction and maximum pore diameter, having a 3.3 to 1 weighting, was the most significant at predicting the fatigue response. Improving fatigue life of forged Ti-6Al-4V made from BEPM should thus be primarily focused on microstructure refinement. It is suggested future experimentation also consider the effects of the number of primary α particles and OE when modeling fatigue strength.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract:
The mechanical properties of a metal are dictated primarily by the metal’s microstructure. The microstructure of a metal made from metal powder that has been pressed and heated to bind the powder together generally contains residual porosity. This generally leads to a reduction in metal fatigue resistance versus a metal that is pore-free.
In studying metal fatigue of a titanium alloy made from metal powder, the resistance to metal fatigue varied considerably and did not achieve the same resistance of pore-free material, despite the titanium alloy in question being nearly pore-free. This titanium alloy was studied to determine what the cause of the poor metal fatigue resistance was. Through a methodical testing program, it was determined that volume fraction of a particular crystalline phase in the microstructure was more damaging than the pores themselves.


title: An Analysis of Commuting Distance and its Controlling Factors in the GTHA

contributor:
Kanaroglou, Pavlos
Geography and Earth Sciences

subject:
Commuting Distance
Extreme Commuters
Jobs-housing balance
Self-Containment
Urban Planning

abstract:
The increasing length of the daily commute is a major issue for many commuters in the Greater Toronto and Hamilton Area (GTHA). In order to alleviate this problem through policy, the policy makers require more in-depth understanding of this issue. This study explores different travel behaviour, socioeconomic and labour market determinants of commuting distance for resident workers in the GTHA, especially those having normal commutes and those having extreme commutes. This study also explores which areas of the GTHA are most self-contained, and what are the average commuting distances of each sub-region of the GTHA. The primary data source for this study was Transportation Tomorrow Survey (TTS) for the year 2011. Supplementary data were obtained from InfoCanada and Statistics Canada.
Descriptive analysis in this study, focused at the Census Sub-Division (CSD), examined self-containment, outbound commutes, inbound commutes, resident employees and jobs densities, and average commute distances for place of residence and place of work. Study results showed that Toronto and Hamilton CSDs are the most self-contained areas in the GTHA, whereas areas located in the north and northwest of Toronto are major sources of outgoing commutes. Toronto and its adjacent CSDs have the lowest average commuting distance, whereas residents of Georgina and Brock commute exceptionally long distances.
Multivariate regression analyses were applied to a disaggregate dataset (TTS). Workers older than 15 years of age living in the GTHA were divided into two major categories based on the length of their commute: (i) normal commuters (those having a mean commuting distance of 10.8 km) and (ii) extreme commuters (those having a mean commuting distance of 40.9 km). Factors affecting commuting distance for these two groups were examined. Similarly, residents living and working in the GTHA were divided into two categories: Resident workers living in (i) Jobs-rich areas or (ii) Resident-rich areas. Factors affecting commuting distance of these resident workers were also examined. The key controlling factors of commuting distance include gender, age, mode of transportation, employment status, ratio of jobs to employed residents, age of youngest child, auto availability in household, multi-worker household, median income, jobs and population density, and distance from CBD. Significant socioeconomic, travel behaviour and land use determinants for normal commute distances were also applicable to extreme commute distance. Transit was the preferred mode of transportation for long distance commuters in the GTHA, except for those living in job-rich areas. Workers associated with Sales and Service occupation and living in jobs-rich areas exhibited shorter commute than those in General/Clerical occupation. These findings are important to understand the changing travel patterns and behaviours of commuters in the GTHA. These results will be of interest to transportation planners, engineers, and policy makers as it highlights the inclination of long distance commuters to use transit.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Roles of Ligands on Silicon

subject: roles, ligands, silicon, silyl, electronegativity, compounds, linear

abstract:
 This thesis presents a study of the roles of ligands on silicon in two parts.

In Part A, the relationship between the β-effect - the ability of a silyl group to stabilize a carbocation β to silicon, and the electron-withdrawing ability of the ligands on silicon was examined. The bromination of a series of (E)-β-silylstyrenes was chosen as a way to quantify the β-stabilization. The degree of syn-addition of bromine to (E)-β-silylstyrene was used as a measure of the stabilizing ability of the silyl group.

 The bromination of a series of four (E)-β-silylstyrenes was investigated [ligands on silicon: (SiMe3O)3; (CH3COO)3; (CCl3COO)3; (CF3COO)3]. It was found that the degree of syn-addition decreases as the silyl group electronegativity increases. Combined with the results previously obtained in our lab, two linear relationships between the degree of syn-addition and the silyl group electronegativity were observed in two groups of (E)-β-silylstyrenes [Group A, ligands on silicon: Me3-nXn, n = 1-3, X= Cl, F and (MeO)3; (Me3SiO)3 and Group B, (CH3COO)3; (CCl3COO)3; (CF3COO)3; (p-MeOPhO)3; (PhO)3; (p-ClPhO)3]. The degree of syn-addition was found to be more sensitive towards the group electronegativity for compounds in Group B. It was also found that, as the group electronegativity increases, the α-SiCH 1H and 29Si NMR chemical shifts of compounds in Group A decrease. In contrast, the α-SiCH 1H and 29Si NMR chemical shifts of compounds in Group B tend to increase.

 In Part B, a series of hydrosilanes were studied and their reactivities in iodination were found to be in the order: CH3SiH(OEt)2 > PMHS > CH3SiHCl2.

 The behavior of these organosilicon compounds is discussed in terms of the structural features of the silyl groups - the ligands on silicon.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Petrographic Study of Pressure Solution Cleavage in Metagreywackes of the Goldenville Formation, Meguma Group, Nova Scotia

subject: petrographic, pressure, solution, metagreywackes, goldenville, formation, cleavage, zones, mineralogical, lithon

abstract:
 Metagreywackes of the Goldenville Formation, Nova Scotia, possess a well developed spaced cleavage. Petrographic evidence suggests that the dominant mechanism producing this cleavage has been pressure solution, involving the dissolution of quartz from cleavage zones. A large amount of shortening occurs during cleavage development due to this volume loss of quartz. Based on a simple comparison of amounts of mica in cleavage and lithon zones shortenings of 50 - 60% have been found.

 Cleavage zones are marked by distinct mineralogical variations, notably a high content of white mica, and a low quartz content. Trends for all components have been documented to characterize the cleavage and lithon zones.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Physical Volcanology of a Pyroclastic Flow Rotoiti Breccia Formation, New Zealand

contributor:
Clifford, Paul M.
Geology

subject: physical, volcanology, pyroclastic, formation, rotoiti breccia, flow, deposit, eruption, particle

abstract:
 The Rotoiti Breccia Formation is a pyroclastic flow deposit located at the northern end of the Taupo volcanic zone, North Island New Zealand. It was formed by a fairly low energy subaerial eruption and subsequent flowage, which restricted it to the topographic low between two older ignimbrites.

 Samples from proximal, medial and distal areas of the flow were examined to determine changes in grain size and particle type distribution as the flow progressed. It was found that on the whole, the flow was very homogenous. However, some initial turbulence at the very beginning of the flow has produced a bimodal grain size distribution presumably due to increased mechanical breakage. A much more prominant crystal population was found in the distal areas of the flow due to rounding of pumice grains and the elutriation of the resultant fines.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Petrography, Geochemistry and Geochronology of the Coe Hill Granite, Hastings County, Ontario

contributor:
Shaw, D. M.
Geology

subject: petrography, geochemistry, geochronology, quartz, granite, monzonite, Coe Hill, pluton

abstract:
 A detailed petrographic, geochemical and strontium isotope study of the rocks representing the variations observed across the Coe Hill granite, Grenville Province, southeastern Ontario provides the basis for the determination of the age and possible origin of this pluton. This study also provides insight into the relationships between similar granitoid plutons in the immediate vicinity.

 The Coe Hill granite is a medium to coarse grained hypidiomorphic to allotriomorphic, leucocratic quartz monzonite with subordinate isolated inclusions of dioritic and gabbroic gneiss. Variations upon this otherwise homogeneous granitoid occur in discordant aplite dykes, assimilating mafic xenoliths and along brecciated contact boundaries.

 Generally the rocks of this pluton are more basic than the average for similar granitoids in the area (12.4% vs. 6.0% mafics) as observed in both thin section and major element oxide diagrams. Besides this trend major element diagrams have uniform distributions. A Rb-Sr isochron was determined for the rocks of the pluton proper which gave an age representative of the emplacement of these rocks (t = 1063 ± 21 M.a.;
Ri = 0.7040 ± 5). Trace element Rb shows a value similar to the norm for granitoids yet is enriched in comparison to values acquired from similar granitoids in the area (144 ppm vs. 63 ppm).

 Through a synthesis of the available data, and that which was acquired from this study on the Coe Hill granite, a comparison with the available data on the Loon Lake quartz monzonite can be made. This comparison illustrates a great deal of strikingly similar trends which have been taken to represent a lower crustal, or upper mantle origin, cogenetic relationship between these two granitoids.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: A Study of the Chemical Cleavage of Benzylic-Silicon Bonds

contributor:
Stöver, H. D. H.
Chemistry

subject: chemical, cleavage, benzyl-silicon, bonds, molecules, polymers, microgels, ion, substrates, oxidation

abstract:
 The key objective of this research was to study the rates of the chemical cleavage of benzyl-silicon bonds in small model molecules, oligomers, polymers, copolymers, and crosslinked microspheres and microgels.

 Substrate species including benzyltrimethylsilane (BTMS), p-isopropylbenzyltrimethylsilane (ISO-BTMS), oligomeric and polymeric vinylbenzyltrimethylsilane (VBTMS), and their copolymers with styrene and methyl methacrylate as well as microspheres and microgels of bis(vinylbenzyl)dimethylsilane (BVBDMS) were synthesized using Grignard reaction, free radical polymerization, and precipitation polymerization.

 Narrow dispersed microspheres were synthesized from bis(vinylbenzyl)dimethylsilane (BVBDMS) by precipitation polymerization in acetonitrile. The reactivities of para/para, meta/meta, and meta/para isomers of BVBDMS in precipitation polymerization were found to be similar and to obey first-order kinetics. Their apparent rate of polymerization is comparable with that of meta and para divinylbenzene isomers under identical polymerization conditions. FT-IR analysis of BVBDMS microspheres shows that there are only few pendant double bonds in the particles. This is likely due to the similar reactivity of isolated double bonds of BVBDMS.

 Two nucleophilic (hydroxide and fluoride ion) and one oxidative (ceric ammonium nitrate) reagents have been used to cleave the benzylic-silicon bonds of the substrates. The cleavage reactions were quantitatively monitored by 1H-NMR / 29Si-NMR or FT-IR to derive the reaction kinetic parameters. The reaction behavior of most of the substrates differed from that expected based on the Flory's principle of equal reactivity.

 Among the hydroxide ion initiated cleavage reactions, the small molecules and the oligomeric analogs obeyed first-order kinetics, but the homopolymer and the copolymers deviated from first-order kinetics. This could be due to the low concentration of hydroxide ion in the polymer matrix, arising from the exclusion of polar hydroxide ion from the hydrophobic polymer matrix. The p-isopropylbenzyltrimethylsilane exhibited a lower pseudo first-order rate than benzyltrimethylsilane. This is attributed to an electron releasing substituent effect. Methyl methacrylate can accelerate the reaction on poly(vinylbenzyltrimethylsilane-co-methyl methacrylate) by increasing the overall copolymer polarity. The reverse is true for the corresponding styrene copolymers owing to the steric hindrance offered by the phenyl ring of styrene, and the enhanced hydrophobic repulsion against the access of hydroxide ion into the polymer matrix. An electrophilically assisted process was proposed as a principal reaction mechanism for this cleavage reaction. It was found that the only nucleophile attacking on silicon would be the hydroxide ion in KOH/EtOH/THF promoted reactions.

 Fluoride ion initiated cleavage reactions of substrates containing benzylic-silicon bonds were found to follow first-order kinetics. The reaction on small molecules was not studied due to their very rapid reaction at room temperature. The homopolymer of vinylbenzyltrimethylsilane exhibited a higher rate of reaction than the corresponding oligomer. However, the change in the reaction rate within a copolymer series, differing in molecular weight and composition, was not significant. Poly(VBTMS-co-MMA) exhibited a rate higher than that of styrene copolymers for polarity or steric reasons.

 Oxidative cleavage of benzylic-silicon bond by ceric ammonium nitrate (CAN) was found to obey first-order kinetics at 1:3 substrate to cerium(IV) ratio, and did not show any deviation in reaction order even at higher CAN concentration. The electron releasing isopropyl group reduces the oxidation potential of p-isopropylbenzyltrimethylsilane (ISO-BTMS), resulting in an enhanced reaction rate compared to benzyltrimethylsilane (BTMS). This rate accelerating substituent effect, together with a much higher negative value (-5.4) of Hammett reaction constant p is in accordance with the radical-cation mechanism operating in ceric ammonium nitrate promoted oxidation reactions. Significant loss of silane functionality was observed in reactions with polymeric substrates. This is attributed to the benzylic radical coupling reactions. The possibility of polymer backbone cleavage is ruled out for the following reasons: A) lack of significant molecular weight reduction in the oxidation products of polymeric substrates. B) about 100 times easier breaking of benzylic-silicon bond as trimethylsilyl cation than a hydrogen from carbon as proton, and the steric congestion offered by the polymer chain favors the benzylic radical formation only at the primary carbon, not on tertiary methine (C-H) on the chain.

abstract: Thesis

abstract: Master of Science (MSc)


title: NMR investigation of the quasi-one-dimensional superconducter class R2Cr3As3 (R = K, Rb or Cs)

contributor:
Imai, Takashi
Physics and Astronomy

subject:
NMR
Superconductivity
Knight shift
Spin-lattice relaxation rate

abstract: Since the high $T_c$ superconductivity was discovered in iron pnictides in 2008, the interplay between the reduced dimensionality, magnetism and unconventional superconductivity has been attracting renewed interest. Recently, Bao et al. and Tang et al. discovered a series of quasi-one-dimensional (quasi 1D) superconductors: \K($T_c=6.1 K$), \Rb($T_c=4.8 K$), and \Cs($T_c=2.2 K$). In this thesis, we will discuss microscopic investigation of \Cs based on nuclear magnetic resonance techniques. The first chapter is a brief introduction to this series of superconductors. The second chapter is a summary of NMR techniques and theory. In the third part, I summarize $^{133}$Cs NMR and $^{75}$As Nuclear Quadrupole Resonance (NQR) measurements on a powder sample of \Cs ($T_c < 1.6$~K). From the $^{133}$Cs NMR Knight shift $^{133}K$ measured at the Cs1 site, we show that the uniform spin susceptibility $\chi_{spin}$ increases from 295~K to $\sim$ 60~K, followed by a mild suppression; $\chi_{spin}$ then levels off below $\sim$10~K. Low frequency Cr spin dynamics, reflected on $^{75}$As $1/T_1T$ (the nuclear spin-lattice relaxation rate $1/T_1$ divided by temperature $T$), shows an analogous trend as $\chi_{spin}$.  Comparison with the results of $1/T_1T$ near $T_c$ with \K($T_c=6.1$~K) and \Rb($T_c=4.8$~K) establishes a systematic trend that substitution of K$^{+}$ ions with larger alkali ions progressively suppresses Cr spin fluctuations together with $T_c$.

abstract: Thesis

abstract: Master of Science (MSc)


title: BIS-MPA DENDRIMERS AS A PLATFORM FOR MOLECULAR IMAGING APPLICATIONS

contributor:
Adronov, Alex
Chemistry and Chemical Biology

subject: Bis-MPA, Dendrimer, Molecular Imaging, Technetium, Click Chemistry, Cathepsin B, PSMA

abstract:
The objective of this research was to develop and validate new macromolecular imaging agents to detect and characterize malignant tumours. Using well-defined, highly branched macromolecules called dendrimers as the structural scaffold, efficient functionalization of the periphery was demonstrated using “click” chemistry in order to prepare multivalent imaging probes. Furthermore, a transmetalation was demonstrated to displace chelated copper with technetium, enabling “click” reactions to be performed in the presence of the dipicolylamine (DPA), a ligand known to chelate many metals.
The dendritic scaffold was functionalized with either hydrophobic or hydrophilic targeting vectors. The hydrophobic ligand, an acyloxymethyl ketone targeting the overexpression of cathepsin B exhibited poor in vitro affinity when coupled to either G1 or G2 dendrimers, despite the use of various linkers. A glu-urea-lys dipeptide, representing a hydrophilic prostate specific membrane antigen targeting vector, demonstrated excellent affinity in vitro. The lead compound, a G2 dendrimer bearing four PSMA targeting vectors attached via an alkyl spacer was further investigated in vitro and in vivo. Unfortunately, poor tumor uptake was observed and the compound was hypothesized to hydrolyze readily (<15min), based on the in vitro plasma stability data. To rectify the aforementioned problem, non neo-pentyl esters were replaced with either carbamate or ether linkages. In vitro plasma stability analysis of the analogous compounds demonstrated increased stability. In particular, the ether analogue was found to be most stable, with minimal degradation observed after 4 hours.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: FUNCTIONAL STUDIES WITH  DIRECT ORAL ANTICOAGULANTS: INVESTIGATION OF THE REGULATION OF KEY BLOOD COAGULATION PROTEASES

contributor:
Weitz, Jeffrey I.
Biochemistry and Biomedical Sciences

subject:
Coagulation
Proteases
Enzyme kinetics
Direct oral inhibitors
Dabigatran
Argatroban
Thrombin
Heparin
Factor Xa
Prothrombinase

abstract: Intrinsic structural and conformational mechanisms regulate the functional specificity of the coagulation system. The study of these structure-function relationships is important for understanding the strategies used in the management of clinical thrombosis. Previous studies have shown that the central enzyme in clotting, thrombin, is sequestered inside of a clot, and protected from the natural downregulator antithrombin (AT). This is problematic for anticoagulants like heparin which depend on AT. Subsequently, it was found that the key upstream propagator of thrombin, the prothrombinase enzyme complex, is also resistant to the AT-heparin. Our data show that further upstream of prothrombinase, the intrinsic tenase is only moderately protected, while there is no protection at the level of the initiator complex, extrinsic tenase. This protection phenomenon possibly reflects steric and allosteric mechanisms that ensure maximal activation of the coagulation system once a threshold stimulus is achieved. These mechanisms likely evolved as a result of conformational rearrangement, as evidenced by the proteolytic activation of thrombin activity following proteolysis of prothrombin. Indeed, subtle differences in the structural interaction of ligands with the active site can lead to substantial differences in enzyme activity. The binding of rivaroxaban and apixaban to factor Xa is nearly identical; both interact with the active site with comparable affinity. Despite this, a 3-fold faster rate of the rivaroxaban on-rate yields significantly greater prolongation of the prothrombin time (PT) and activated partial thromboplastin time (aPTT), global tests of coagulation. These small differences in ligand interaction also have allosteric consequences. Structural differences between the direct thrombin inhibitors dabigatran and argatroban yield divergent exosite-mediated thrombin binding to physiologic ligands like yA-fibrin, y'-fibrin, factor Va, and factor VIII, interactions that govern clot-mediated protection from AT inhibition, and the various functions of thrombin. These divergent effects were robust and ligand-dependent, suggesting conserved energetic scaffolds within the thrombin molecule that govern allosteric changes throughout the molecule. Because proteolysis of prothrombin yields significant allosteric and structural rearrangement that capacitates the active site for substrate recognition amd catalytic ability, we investigated the role of Ser195, a key residue in the thrombin catalytic triad in also regulating thrombin allostery. Site directed mutagenesis of Ser195 to Ala yielded a significant increase in the flexibility of the entire thrombin molecule, as evidenced by increased potency of dabigatran and argatroban in terms of their capacity to modulate exosite binding through the active site, and increased interexosite cooperative and competitive allostery. Together, these studies represent an advance in our understanding of the consequences of both small molecule ligation of coagulation proteases, as well as the consequences of subtle structural modification for overall allosteric function.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A Pneumatological Vision of God: The Holy Spirit and Classical Theism's Doctrine of the Divine Attributes

contributor:
Studebaker, Steven M.
Peterson, James C.
Pinnock, Clark H.
Christian Theology

subject: pneumatological, vision, God, spirit, holy, theism, doctrine, divine, attributes, Christian, deity

abstract: Historically, pneumatology has had little influence on the Christian doctrine of God. In particular, although Christians throughout the ages have defended the deity of the Spirit, they have not adequately taken the economic activity of the Spirit into consideration when formulating the doctrine of the divine attributes. In an effort to correct the historical lack of influence that pneumatology has had on the doctrine of the divine attributes, this book advocates and explores the potential of a pneumatological approach to the doctrine of the divine attributes by presenting pneumatological revisions to classical theism. The thesis of this book is that a pneumatological approach to the doctrine of God recovers an emphasis on divine immanence, which has been marginalized by classical theism's imbalance toward divine transcendence. After the introductory chapter, chapter two illustrates how classical theism neglects the doctrine of the Trinity (and pneumatology in particular) in its formulation of the doctrine of the divine attributes and how classical theism privileges divine transcendence. Chapter three provides a review of how process theologians, evangelical theologians, and trinitarian theologians critique and revise classical theism and displays how contemporary theologians have only begun to develop a pneumatological approach to the doctrine of the divine attributes. Chapter four continues by recommending a pneumatological approach to the divine attributes. The remainder of the book illustrates how pneumatology provides a way to revise the classical accounts of divine impassibility, immutability, and omnipotence. In contrast to classical conclusions regarding these doctrines, pneumatological perspectives on the doctrine of the divine attributes portray God as suffering, changing his presence, and exercising his omnipotence kenotically.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: An Investigation of Teneral Matings, Male Coercion, and Female Response. A Second Investigation of Caffeine Tolerance in Drosophila Melanogaster

contributor:
Dukas, Reuven
Psychology

subject: teneral, matings, male, coercion, female, caffeine, tolerance, drosophila, melanogaster, progeny

abstract:
 Chapter 1-4 focuses on investigating whether forced copulations occur in teneral females, and how the female responds. There has only been one paper to report mating in newly eclosed (teneral) female matings in fruit flies (Drosophila melanogaster), and it was suggested to be forced. The focus of this thesis is to determine whether teneral matings are forced and how this may affect the future remating and reproductive success of females. Within the thesis, chapter 1 and 4 results suggest that teneral matings occur in both Canton-S and wild caught females, and occur in females less than 30 minutes post eclosion. Chapter 3 compared the male/female interaction of teneral females vs. immature females that successfully reject male mating attempts. Males were more aggressive with teneral females, and females displayed more rejection behaviours during courtship and mating. Chapter 4, was aimed at investigating what the reproductive consequences are, and results suggest that a teneral mating yields less progeny than a mature mating, and 68% of tenerally mated females remate at maturity.

 Chapter 5 and 6 focuses on investigating whether situational caffeine tolerance can be developed in fruit flies. Chapter 5 results indicate that caffeine causes a rest disruption, and a general tolerance to the rest disrupting effects can be gained over 6 days of repeated administration. The experiments in chapter 6 used various protocols to investigate whether a situational tolerance will develop, using odours and colours as associative cues. No conclusive results were found.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Impact of Bisphenol A Exposure on Implantation, Steroid Hormone Excretion, Uterine Morphology and Receptor Expression in Inseminated Female CF-1 Mice

contributor:
deCatanzaro, Denys
Psychology

subject: bisphenol, implantation, steroid, hormone, excretion, uterine, morphology, receptor, inseminated, female, mice, cells

abstract: Bisphenol-A (BPA), used in the production of polycarbonate plastics and epoxy resins, has established estrogenic properties. Early pregnancy in mice is highly sensitive to exogenous estrogens, particularly during the period of blastocyst implantation. Accordingly, I assessed pregnancy outcome, implantation, urinary hormone levels and uterine morphology following BPA exposure. Subcutaneous injections of BPA administered on days 1 through 4 of gestation reduced litter size at a dose of 3 mg/animal/day and decreased the proportion of parturient females at 10 mg/animal/day. Hysterectomies performed on day 6 of pregnancy confirmed a significant disruption of implantation occurring at doses as low as 6 mg/animal/day. Urinary progesterone levels were also reduced by 10 mg/animal/day. Uterine luminal area expanded substantially in response to increasing doses of BPA. Luminal epithelial cell height increased following exposure to 10.125 mg/animal, whereas there were no differences in the number of corpora lutea among conditions. The proportion of cells staining positively for estrogen receptors was affected non-monotonically, showing highest levels at 3.375 mg/animal and lowest levels at 10.125 mg/animal. Similarly progesterone receptor expression measured through western blots related non-monotonically to dose, being highest at 3.375 mg/animal and diminishing with increasing dose. Effects of a single administration of BPA on days 0, 1, or 2 of gestation were also investigated. A single dose of 10 mg reduced the number of implantation sites when given on day 0 or 1, and 6 mg did so on day 1, but there was no such effect of any dose administered on day 2. Exposure to low, environmentally-relevant doses of BPA did not result in any clear reproductive or hormonal effects. These studies highlight the detrimental effects BPA exposure induces during early pregnancy and provides further evidence of its weak estrogenic properties in vivo.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Advanced Electromagnetic System Analysis for Microwave Inverse and Design Problems

contributor:
Nikolova, N. K.
Electrical and Computer Engineering

subject: electromagnetic, system, analysis, microwave, inverse, design, problems, computational, response-level

abstract:
 This thesis contributes significantly to the advancement of the response sensitivity analysis with time-domain electromagnetic (EM) solvers. The proposed self-adjoint sensitivity approaches achieve unprecedented computational efficiency. The response Jacobians are computed as a simple post-process of the field solution and the approaches can be applied with any commercial time-domain solver. The proposed sensitivity solvers are a breakthrough in the sensitivity analysis of high-frequency structures since they can be implemented as standalone software or plugin for EM simulators. The goal is to aid the solution of microwave design and inverse problems.

 The sensitivity information is crucial in engineering problems such as gradient-based optimization, yield and tolerance analyses. However, due to the lack of robust algorithms, commercial EM simulators provide only specific engineering responses not their sensitivities (or derivatives with respect to certain system parameters). The sensitivities are typically obtained by response-level finite difference (FD) approximations or parameter sweeps. For each design parameter of interest, at least one additional full-wave analysis is performed. Such approaches can easily become prohibitively slow when the number of design parameters is large.

 However, no extra system analysis is needed with the self-adjoint sensitivity analysis methods. Both the responses and their Jacobian are obtained through a single system analysis. In this thesis, two self-adjoint sensitivity solvers are introduced. They are based on a self-adjoint formulation which eliminates the need to perform adjoint system analysis. The first sensitivity solver is based on a self-adjoint formula which operates on the time waveforms of the field solution. Three different approaches associated with this sensitivity solver have been presented. The first approach adopts the staggered grid of the finite-difference time-domain (FDTD) simulation. We refer it as the original self-adjoint approach. The second approach is the efficient coarse-grid approach. It uses a coarse independent FD grid whose step size can be many times larger than that of the FDTD simulation. The third approach is the accurate central-node approach. It uses a central-node grid whose field components are collocated in the center of the traditional Yee cell.

 The second self-adjoint sensitivity solver is based on a spectral sensitivity formula which operates on the spectral components of the E-field instead of its time waveforms. This is a memory efficient wideband sensitivity solver. It overcomes the drawback associated with our first sensitivity solver whose memory requirements may become excessive when the number of the perturbation grid points is very large. The spectral approach reduces the memory requirements roughly from Gigabytes to Megabytes. The focus of this approach is on microwave imaging applications where our first sensitivity solver is inapplicable due to the excessive memory requirements. The proposed sensitivity solver is also well suited for microwave design problems.

 The proposed self-adjoint sensitivity solvers in this thesis are verified by numerous examples. They are milestones in sensitivity analysis because they have finally made EM simulation-based optimization feasible.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Hilbert Transform

contributor:
Bennett, C.
Mathematics

subject: Hilbert, transform, integers, unit circle, complex, bilinear, proofs

abstract:
Abstract Not Provided.
Thesis
Master of Science (MSc)


title: Metamorphism in the George River Group Cape Breton Island, Nova Scotia

contributor:
Burley, B. J.
Geology

subject: metamorphism, rocks, George River Group, Cape Breton Island, minerals, hydrolysis, formation, granitic

abstract:
 A sequence of metasedimentary rocks comprising the George River Group, Cape Breton Island, Nova Scotia, was studied. A petrographic examination of the five different rock types present -- marbles, amphibolites, paragneisses, skarn xenoliths, and granitic bodies was carried out. A petrochemical analysis, using X.R.F. methods was also completed.

 The GRG has undergone three distinct periods of metamorphism. The first was a period of kyanite grade regional metamorphism, believed related to the Grenville orogeny. High grade metamorphic minerals developed in the various lithologies present in the GRG. These minerals were kyanite, diopside, forsterite, hornblende, and muscovite.

 A chlorite grade regional metamorphism followed, creating such low grade minerals as chlorite, sericite, and serpentine. These minerals formed by the hydrolysis of higher grade metamorphic minerals.

 Following this low grade metamorphism, the GRG was subjected to a period of wollastonite grade contact metamorphism. This metamorphic period resulted from the injection of smaller granitic bodies believed related to the Acadian orogeny. The formation of contact metamorphic minerals such as, wollastonite, vesuvianite, phlogopite and sphene characterize the assemblages formed by this metamorphic event.

 The petrochemical analysis shows that these meta-sedimentary GRG rocks had protoliths of several types, including siliceous dolomitic limestones, siliceous limestones, greywackes, and basic volcanic sills. The amphibolites present crossing the GRG formed by the metamorphism of the basic volcanic sills.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: DISCOVERY AND CHARACTERIZATION OF NOVEL BETA-LACTAMASE INHIBITORS

contributor:
Wright, Gerard D.
Chemistry and Chemical Biology

subject:
Chemical Biology
Antibiotic Resistance

abstract:
The discovery of antibiotics and their subsequent clinical use has had a tremendous and beneficial impact on human health.  The β-lactam antibiotics, which include penicillins, cephalosporins, carbapenems, and monobactams, constitute over half of the global antibiotic market.  However, like all antibiotics, the β-lactams are susceptible to bacterial antibiotic resistance.  One of the most disconcerting manifestations of bacterial resistance to β-lactam antibiotics is the evolution and dissemination of β-lactamases, enzymes able to chemically inactivate β-lactam antibiotics.  These resistance determinants are the key contributing factor to extensively-drug resistant Gram-negative pathogens, for which we are already bereft of chemotherapeutic treatment options in some cases.
The coadministration of a β-lactamase inhibitor (BLI) with a β-lactam antibiotic is a proven therapeutic strategy to counter β-lactamase expression.  Unfortunately, the emergence of both serine β-lactamases (SBLs) that are resistant to BLIs and metallo-β-lactamases (MBLs), which are intrinsically resistant to BLIs due to a discrete mechanism of β-lactam hydrolysis, threaten the efficacy of combination therapy.  Notwithstanding this bacterial adaptation, the discovery and development of novel BLIs is an attractive strategy to evade resistance, as evidenced by the recent clinical approval of the diazabicyclooctane (DBO) SBL inhibitor, avibactam.
Herein, I describe efforts directed at understanding the mechanism of avibactam SBL inhibition.  Furthermore, DBO derivatives are shown to display bifunctional properties in inhibiting both β-lactamases and the targets of β-lactam antibiotics, the penicillin-binding proteins.  In addition to understanding the enzymology and chemical biology of DBOs, I describe two screening campaigns directed towards discovering inhibitors of MBLs, an unmet clinical need.  Using target and cell-based screening of both synthetic and natural product chemical libraries, a fungal natural product inhibitor of clinically relevant MBLs was discovered and characterized.
This study expands our understanding of the mechanisms by which DBOs can be used to combat extensively drug-resistant Gram-negative pathogens.  It also describes the discovery of a new natural product MBL inhibitor using a workflow that should be amenable to other resistance determinants.  It’s hoped that these studies can contribute meaningfully to countering antibiotic resistance observed in clinical settings.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Beta-lactam antibiotics like penicillin are a mainstay for treatment of bacterial infections.  Bacterial resistance to these antibiotics threatens their utility and therefore new strategies are required to counter this phenomenon.  Herein I describe efforts aimed at understanding new drugs and candidate drugs that act by inhibiting the function of enzymes produced by bacteria that are able to degrade beta-lactam antibiotics.  Through the discovery of new molecules and an understanding of their chemical mechanism of inhibition it is believed that bacterial resistance to beta-lactam antibiotics can be reversed.


title: Oxygen and Hydrogen Isotope Studies of Metamorphic Rocks in the Wawa-Kapuskasing Crustal Transect, Ontario, Canada

contributor:
Shaw, D. M.
Schwarcz, H. P.
Geology

subject: oxygen, hydrogen, isotope, metamorphic, rocks, crustal, transect, terrains, magma, fluid

abstract:
 Oxygen and hydrogen isotopic distributions have been studied for rocks from a 100 km transect in the central Superior Province of Ontario, Canada. The transect represents progressively deeper terrains of the Michipicoten Greenstone Belt (MGB), the Wawa Gneiss Terrane (WGT), and the Kapuskasing Structural Zone (KSZ), which correspond to an increase of metamorphic grade and are interpreted as an oblique section through approximately 20 km of crustal thickness. The rocks in the terrains range in age from ~2.76 to ~2.60 Ga, with fewer later intrusions.

 Equivalent lithologic types have similar δ18O range at middle and lower crustal levels (WGT and KSZ). Tonalitic to granodioritic rocks range from 6.4%o to 9.5o/oo; Dioritic and anorthositic rocks range from 5.5o/oo to 7.6o/oo; a majority of the mafic gneisses (group 1) range from 5.7o/oo to 7.1o/oo, while group 2 mafic gneisses range from 8. 1o/oo to 9.5o/oo. δ18O values of the rocks exhibit a remarkable correlation with SiO2 values, similar to that observed in unaltered plutonic rocks of equivalent composition. Paragneisses have significantly higher δ18O values, 9.3o/oo to 12.2o/oo. Low-grade metavolcanic and metasedimentary rocks of the MGB are 18O-enriched compared to their high-grade equivalents in the KSZ and WGT, 7.4o/oo to 13.3o/oo for mafic to felsic metavolcanic rocks and 11.4o/oo to 14.7o/oo for clastic metasediments.

 Coexisting minerals from high-grade rocks exhibit 18O-fractionation closely consistent with isotopic equilibrium, suggesting that the isotopic system has not been grossly disturbed. Isotopic thermometers give uniform apparent temperatures, about 553°C to 584°C, across the entire transect, which are lower than the inferred metamorphic temperatures in the highest-grade (KSZ) terrane.

 The lack of distinctive isotopic differences between equivalent rock types in the KSZ and WGT suggests that there is no significant gradient in δ18O with depth in the crust or with metamorphic grade. The majority of mafic gneisses (Group 1) have δ18O values similar to fresh basalts and appear to have been emplaced either as subaerial extrusives, intrusive sills, or, less likely, as submarine extrusives that were hydrothermally altered at high temperatures. The less abundant Group 2 mafic gneisses have δ18O values typical of greenstones that were altered at low temperature by sea-water, and isotopically resemble low-grade rocks in the Michipicoten and Abitibi belts. In general, no major changes in whole-rock isotopic composition appear to have occurred during granulite facies metamorphism, implying limited flux of water or CO2.

 The continuous linear gradient in δ18O vs SiO2 in the high-grade rocks cannot be due to differentiation of a mafic source magma. A model involving an association between mantle-derived mafic magma and 18O-enriched crustal materials is more consistent with the oxygen isotopic data.

 Hydrogen isotope composition of hornblende and biotite has been analyzed from selected rocks. Mafic and anorthositic rocks from the KSZ have δD values from -58 to -62o/oo, suggesting a possible mantle-derived origin of fluid in the system. Two mafic gneisses, which are 18O-enriched, show lower δD values, -89 and -101o/oo. The depletion of deuterium is consistent with the model of low temperature alteration with seawater in a submarine environment. Mafic and tonalitic gneisses from the WGT are also depleted in deuterium, -87 to -109o/oo. Since these rocks intruded into relatively higher level of the crust and commonly contain secondary alteration minerals, it is possible that hydrothermal alteration took place at late- or post-metamorphism stage, and the source of the fluid is likely meteoritic water, The amount of water involved in the exchange was restricted, and was not enough to disturb the oxygen isotopic system in the rocks.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Mechanisms of Amide Hydrolysis

contributor:
Bader, R. F. W.
Chemistry

subject: mechanisms, amide, hydrolysis, acid, catalyzed, molecular, atoms, reaction

abstract:
 This thesis presents the theoretical study of the mechanisms of gas-phase formamide hydrolysis using ab initio SCF-MO calculations. Four reaction paths were considered; (i) the reaction of formamide with OH- (ii) the acid catalyzed hydrolysis with protonation on the nitrogen atom (iii) the acid catalyzed hydrolysis with protonation on the oxygen (iv) the uncatalyzed hydrolysis. An unconstrained optimization of all parameters was performed on the
transition state and equilibrium structures. The intrinsic reaction coordinate was then followed down from the transition state to the reactants and products. All of the molecular geometries were obtained using the 4-31G basis set and all wavefunctions and energies were calculated at the 6-31G** level of theory. The theory of atoms in molecules was applied to each reaction to study the mechanisms of structural change along the reaction coordinate. Molecular graphs were calculated at points along the reaction coordinate and these give a detailed pictorial outline of the entire reaction sequence. The Laplacian of the charge density successfully predicts the correct site of protonation and the enhanced reactivity of protonated formamide
over that of neutral formamide. Both the acid catalyzed reaction with nitrogen protonation and the base enhanced hydrolysis reactions proceed without a barrier with respect to reactants and products. The acid catalyzed hydrolysis with protonation on the oxygen atom proceeds with a moderate activation barrier whereas the neutral hydrolysis involves the
passage over a very high activation barrier. The two acid catalyzed reactions are competitive with the N-protonation mechanism being more favourable from a kinetic point of view while the O-protonation mechanism is thermodynamically more favourable.

abstract: Thesis

abstract: Master of Science (MSc)


title: Evaluation and Application of Radiochemical Neutron Activation to Noble Metal Analysis

contributor:
Crocket, James H.
Geology

subject: evaluation, application, radiochemical, neutron, activation, noble, metal, analysis, greenstone

abstract:
 A rapid and simple radiochemical neutron activation technique involving tellurium coprecipitation of Au, lr, Pd and Pt was evaluated using the U.S.G.S. standards PCC-1 (peridotite) and DTS-1 (dunite) as well as a house standard, JHC-6 (spinifex zone of a komati itic peridotite). It was then applied to the analysis of samples of Archean greenstone from the Red Lake area.

 The technique gives detection limits of 0.01-0.02, 0.02, 0.1-0.4 and 1-2 ppb for Au, Ir, Pd and Pt respectively and precisions of <25-35%. The method can be successfully applied to the analysis of PGE levels in sulphur-poor rocks, and large numbers of samples can be processed in a short period of time.

 A comparison of PGE content between several types of mafic rocks was made as well as an investigation of possible secular trends (Archean vs. Phanerozoic) in PGE concentration.

abstract: Thesis

abstract: Master of Science (MSc)


title: Structures of the Kalsilite-Like Silicates MTSiO4 (M = Ba, Na/K, Ca/Sr; T = Co, Mg, Zn, Ga, Be)

subject: structures, silicates, compounds, diffraction, single, crystal, atoms

abstract: A number of silicate compounds BaTSiO4 (T = Co, Mg, Zn), Na0.5K0.5GaSiO4 and Sr1-xCaxBeSiO4 (x = 0.0 ~ 0.4) have been characterized by a combination of diffraction techniques. These compounds crystallize with the same (√3XA, C) superstructure of the hexagonal kalsilite (KAlSiO4) structure and belong to the large structural family of stuffed tridymite-derivatives. Their crystal structures have been refined by using powder neutron data (BaTSiO4, T = Mg, Zn), powder X-ray data (Na0.5K0.5 GaSiO4) and single crystal X-ray data (BaCoSiO4 and Sr1-xCaxBeSiO4, x = 0.0 and 0.27). This study shows that these kalsilite-like structures can accommodate cavity and tetrahedral atoms of variable sizes by relatively minor framework distortions and atomic displacements. The formation of the (√3XA, C) superstructure can be correlated with the relative sizes of the tetrahedral and cavity atoms.

abstract: Thesis

abstract: Master of Science (MSc)


title: Isotopic Studies of the Groundwaters and their Host Rocks and Minerals from the Underground Research Laboratory (URL), Pinawa, Manitoba, Canada

contributor:
McNutt, R. H.
Schwarcz, H. P.
Geology

subject: isotopic, groundwaters, minerals, rocks, underground, research, laboratory, Manitoba

abstract:
 This is a study of the groundwaters and their associated rocks and minerals from the Lac du Bonnet batholith at the Underground Research Laboratory (URL), Pinawa, Manitoba, to assess the water-rock interaction in crystalline rocks by using Sr, O and U-series isotopes. Emphasis is also placed on the development of the analytical techniques.

 A high precision analytical technique of U-series isotopes has been developed in this study by using solid-source mass spectrometry. A precision of better than 1% (2σ) is achieved in determining the 234U/238U and 230Th/234U ratios using 10^-8 g of U and 10^-11 g of 230Th. The potential applications of this method is demonstrated by dating small speleothem samples and the results agree well with those of α-spectrometry. This method also applies well
to precise determination of the 234U/238U ratios in groundwaters and igneous rocks and minerals using small quantities of samples. However, precise measurements of 230Th in igneous rocks and minerals are limited by the large 232Th tail in the Th mass spectrum. Even better precision is achievable if pure Th spike is used.

 An ICP-MS isotope dilution method is also developed for fast and precise determination of Sr concentrations in groundwater samples. A precision of 1% is routinely achieved by taking into account the dead-time effect of the Channel Electron Multiplier (CEM) and the sample-to-spike ratios.

 The isotope results of both the groundwaters and the host rocks and minerals have revealed the processes of water-rock interaction and water mixing through the history of the batholith. Strontium isotope systematics of the rocks and their constituent minerals have shown that Sr loss occurred on whole-rock scale during both the high-temperature alteration (about 2300 Ma ago) and the low-temperature alteration which lasted at least 450 Ma. The Sr loss is most pronounced in plagioclase of altered samples. Uranium-series results indicate the disequilibrium of both whole-rock samples and minerals, and migration of U on whole-rock scale in, at least, the last million years.

 The Sr and O isotopic results have shown that the groundwaters from the three sub-horizontal, successively deeper fracture zones (FZ) have distinct isotopic signature: 87Sr/86Sr= 0.715 to 0.719 and 𝛿18O=-13o/oo for FZ-3; 87Sr/86Sr= 0.720 to 0.729 and 𝛿18O=-13 to -20o/oo for FZ-2; 87Sr/86Sr= 0.730 to 0.738 and 𝛿18O=-13 to -17o/oo for FZ-1. Uranium-series results show that all the groundwaters are highly enriched in 234U and the 234U/238U activity ratios range from 2.6 to 7.7. Mixing of three groundwaters is indicated by the Sr and O isotopes and the elemental chemistry. The three end-members are fresh surface water, the deep fresh (possibly glacial melt) groundwater and the deep saline groundwater.

 Comparison between the rocks and associated groundwaters shows that Sr isotopic equilibrium exists between plagioclase of altered samples and the groundwaters. This similarity indicates the vulnerable mineral phase control, such as plagioclase in this case, of the isotopic signatures, hence, chemistry of the groundwaters.

abstract: Thesis

abstract: Master of Science (MSc)


title: Determination and Analysis of Turbidity over Hamilton, Ontario

contributor:
Davies, J. A.
Geography

subject: turbidity, determination, analysis, radiation, synoptic, beam

abstract:
 Turbidity over Hamilton is determined using direct beam radiation in two manners for the summer period of 1975. These turbidities are then studies with respect to local regional and continental synoptic air masses.

 The results of the study show a high correlation between the actinometric and residual methods of determining direct beam radiation. This allows turbidity to be easily evaluated at radiation measurement sites.

 The most significant influence on the amount of particulate matter over Hamilton is the continental scale synoptic patterns.</p.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Solvent Extraction Preconcentration of Trace Metal Ions from Natural Waters with an Alkylated Oxine Derivative

contributor:
Corsini, A.
Chemistry

subject: solvent, extraction, preconcentration, trace, metal, ions, alkylated, oxine, derivative, natural, waters

abstract:
 A method for the simultaneous preconcentration by solvent extraction of a group of trace metal ions from natural waters has been developed. The procedure makes use of a proprietary "liquid cation-exchanger", Kelex 100, the primary component of which is an alkylated oxine (8-quinolinol) derivative, 7-(4-ethyl-1-methyloctyl)-8-quinolinol (HL). After purification of HL from the commercial mixture, the extraction of ten environmentally-significant trace metal ions from artificial seawater into toluene solution was studied as a function of pH. From these investigations, the optimal conditions for the extraction of Cd(II), Co(II), Cu(II), Mn(II), Ni(II), Pb(II) and Zn(II) from natural waters were established. The conditions for quantitative back-extraction of the metal ions were then investigated. With the exception of cobalt, the metal ions were quantitatively back-extracted into a small volume of nitric acid, simplifying the matrix and providing additional analyte enrichment. The optimized forward- and back-extraction technique was subsequently applied to the determination of total (soluble) Cd, Cu, Mn, Ni and Pb in a coastal seawater reference standard by graphite-furnace atomic absorption spectroscopy (GFAAS). The quantitative recovery of the analytes and the uncomplicated matrix of analysis enabled quantitation to be carried out by external calibration. Compared to the method of standard additions, external calibration has advantages in overall analysis time and sample consumption. Satisfactory agreement was obtained between the experimental and reference values, although Cu(II) blanks were high due to trace Cu(II) contamination of HL and the stability of the Cu(II)-HL chelate.

 The lipophilicity of HL and its metal chelates provided high metal chelate distribution ratios which, in turn, permitted preconcentration factors of up to 500 in a single batch-extraction. Additionally, studies on the recovery of radiotracer spikes from lakewater and seawater suggested that HL is an effective extractant for stripping metal ions from variously-bound forms from natural waters.

abstract: Thesis

abstract: Master of Science (MSc)


title: Some Aspects of Growth in the Space Economy

subject: aspects, growth, space, economy

abstract:
Abstract Not Provided.
Thesis
Master of Arts (MA)


title: Structural Studies of Derivatives of Thiazolidine-4-Carboxylic Acid

contributor:
Lock, C. J. L.
Chemistry

subject: structural, derivatives, carboxylic, acid, sulfur, compounds, ionized, molecules

abstract:
 A series of derivatives of thiazolidine-4-carboxylic acid was prepared from two sulfur containing aminoacids, cysteine and D-penicillamine. Cysteine is very easily oxidized to a disulfide, while penicillamine is less susceptible to oxidation of the sulfhydryl group because of greater steric hindrance. Sulfhydryl aminoacids react readily with aldehydes and ketones to give thiazolidine rings with varying degrees of substitution.

 Many of the compounds prepared were studied in solution and in the solid state by means of nmr, vibrational spectroscopy, mass spectra and X-ray crystallographic data. Thiazolidine-4-carboxylic acids contain a free carboxyl group and a secondary amino group, both of which can be ionized. Infrared spectra and X-ray crystallography are useful in detecting ionization and hydrogen bonds. An example is given of a compound that can exist in both the zwitterion and the non ionized state depending on the solvent of recrystallization.

 From previous work in our group we were predicting that increasing steric crowding in the thiazolidine ring in close proximity to the ionizable groups would decrease the tendency of these molecules to ionize. No such simple relationship could be found.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Combination of Microbore Liquid Chromatography and Mass Spectrometry

contributor:
Quilliam, M. A.
Chemistry

subject: combination, mictobore, liquid, chromatography, mass, spectrometry, calibration

abstract:
 An inexpensive method was developed for the conversion of a high performance liquid chromatography (HPLC) system for use with 1 mm I.D. microbore columns. Chromatographic performance of the system was tested under both isocratic and gradient elution conditions, using a standard mixture of 16 polycyclic aromatic hydrocarbons (PAH).

 The microbore column HPLC was also coupled to a mass spectrometer equipped with a moving belt interface. Chromatographic performance under isocratic and gradient elution and mass spectral performance under scanning and selected ion monitoring modes were tested using the PAH standard.

 A marine sediment extract was subjected to qualitative and quantitative analysis for PAH. Qualitative results on the sample were obtained from a combination of retention indices, mass spectra, and retention times. Quantitation was performed by microbore column liquid chromatography-mass spectrometry (LC/MS) in the selected ion monitoring mode of operation. The method of calibration used was external calibration.

 The microbore column HPLC system exhibited good chromatographic behavior. Resolution, peak shape and short term retention time reproducibility were good, although, long term retention time fluctuations, due to changing mobile phase flow rates, were noted.

 The combination of microbore column HPLC with a moving belt interface and mass spectrometer gave excellent results. Problems commonly encountered with conventional column (4.6 mm I.D.) LC/MS, such as backstreaming, droplet formation, and splattering were greatly reduced, resulting in no apparent loss of chromatographic integrity and stable mass spectrometer operating conditions. These operating conditions proved to be most advantageous in the quantitative analysis of the marine sediment extract by selected ion monitoring.

abstract: Thesis

abstract: Master of Science (MSc)