VictorJuiz/thesis huggingface dataset:
Localized Corrosion of FrictionStir Spot Welds in AZ31 Magnesium Alloys

A scanning reference electrode technique (SRET) apparatus has been designed and commissioned to investigate the corrosion of friction stir spot welds (FSSW) made in AZ31 magnesium alloys. The operational parameters of the apparatus have been calibrated to give good spatial resolution. By combining the SRET data with material flow data and immersion test data it was found that the FSSW process caused the formation of distinct noble and active regimes within the weld area. The noble region was aligned with the stir zone (SZ) and was caused by a dynamically recrystallized grain structure which is void of dislocations / twins, and β Mg17Al12. Localized corrosion attack was observed in both SRET and immersion testing along the thermo-mechanically affected zone (TMAZ). The same effect was consistently observed with a flat versus concave shoulder tool, and dwell times of 1s and 4s.

Keywords: Corrosion
Magnesium
Friction Stir Spot Weld
AZ31
Advisor: North, Thomas H.
Thorpe, Steven J.
Highly Transparent Glass using Nanoparticle Films for Enhanced Optoelectronics

This thesis provides an investigation and review of homogeneous multilayer anti-reflective coatings (ARC) on glass. Recently, numerical optimization has become popular in optimizing the number of layers at a defined wavelength range and at angular incident angles. In this investigation, the design of the index profile is optimized for normal incident angle and angular incident angles by an evolutionary genetic algorithm. The anti-reflective coatings consist of multilayer porous silica or tin oxide nanoparticle films, which are fabricated by mixing 10nm silica nanoparticle or 10nm tin oxide nanoparticle colloidal solutions with varying amounts of 50nm polystyrene colloidal solutions, followed by spin coating on a glass substrate, and sintering at 400˚C for 40 minutes, which burns off the embedded polystyrene and renders a voided matrix. Experiments were carried out to produce ARCs based on well-known index profiles, and based on genetic algorithm optimization

Keywords: antireflection coats
glass
Advisor: Kherani, Nazir P.
Glycemic Index, Oxidized LDL, and CHD Risk

The aim was to determine whether the dietary glycemic index (GI) related to coronary heart disease (CHD) risk and whether oxidized LDL could explain this relation. Nine prospective cohorts of GI or glycemic load (GL) associations were pooled in a meta-analysis and showed an increased risk of CHD for high GI (near significant at RR=1.13, 95%CI; 1.00-1.26) and GL diets (significant at RR=1.40, 95%CI; 1.17-1.68), both with significant evidence of heterogeneity (P<0.07). Sera from 151 type 2 diabetics who completed a 6-month trial of a low GI diet demonstrated no treatment difference in measures of oxidative damage. However, when data from both treatments were pooled, oxidized LDL as a marker of CHD risk inversely related to low GI carbohydrate intake. We conclude that GI and GL relate to CHD and oxidative damage to LDL may explain part of this association.

Keywords: Glycemic Index
CHD
Oxidative Damage
Heart Disease
Advisor: Jenkins, David J. A.
Sievenpiper, John L.
Characterization of Escherichia coli Single-gene Deletion Mutants Impaired in Bacteriophage Reproduction

An assay was designed to measure the sensitivity of Escherichia coli mutants to bacteriophage infection via growth curves, using a Tecan temperature controlled plate reader. I screened 3985 single-gene deletion strains in Escherichia coli K12 from the Keio collection and identified 43 strains displaying varying degrees of resistance to four different phages, three non-contractile tailed phages (λcI857, HK97, and HK243) and the myoviridae T6, including 20 genes not previously implicated in phage infection. Additional assays, such as adsorption and tests of DNA-injection, were designed to further characterize resistant strains. The use of these assays helped identify varying sensitivities to LPS structure and LamB receptor concentration in the three non-contractile tailed phages, showing HK97 is the most sensitive to changes and HK243 the least. I also found that the periplasmic chaperone, FkpA, is required for HK97 DNA-injection.

Keywords: Bacteriophage
Bacteriophage Resistance
Genetic Screen
Escherichia coli
Advisor: Davidson, Alan R.
Edwards, Aled M.
Barriers & Facilitators to Overcoming Obesity in Canada and the Role of Fat-related Nutrient Content Claims

Our overall objective was to explore some individual and environmental determinants of eating habits with a main focus on nutrition labels and their usefulness for choosing foods for weight management. We first broadly examined these determinants using participants of the AFMNet Canadian Consumer Monitor (CCM), and found a number of attitudinal and perceived environmental barriers to healthy eating. In an experimental study with CCM respondents, we found that reduced fat claims may help consumers make better choices for weight management if calorie content on the Nutrition Facts Table is also considered. However, in our examination of foods with fat claims in the Canadian marketplace, we found that most products with fat claims are not significantly lower in calories than comparable foods without such claims. We conclude that fat claims could be useful in assisting consumers with food choices for weight management, if the foods were also reduced in calories.

Keywords: obesity
nutrient content claims
nutrition policy
nutrition regulations
fat claims
weight management
food choice
consumer survey
nutrition labelling
Advisor: L'Abbe, Mary R.
Molecular Characterization of a Recurrent t(2;7) Translocation Linking CDK6 to the IGK Locus in Chronic B-cell Neoplasia

Uncovering the chromosomal abnormalities associated with human malignancy can provide significant insights into the molecular basis of tumorigenesis, as well as identifying potential targets for therapy. The present study set out to examine the genetic characteristics of t(2;7)(p11-12;q21-22) translocations arising in conjunction with chronic B-cell neoplasia. Using long-range PCR, a t(2;7) was initially mapped in an individual presenting with the preclinical entity CD5- monoclonal B-cell lymphocytosis. This revealed a breakpoint at 2p11.2 localized to the recombination signal of the immunoglobulin kappa (IGK) variable gene IGKV3-15, and a breakpoint at 7q21.2 located 520 bp upstream of cyclin dependent kinase 6 (CDK6). The same approach was subsequently employed to elucidate near-identical t(2;7) breakpoints in 4 additional cases presenting with chronic lymphocytic leukemia or indolent non-Hodgkin lymphomas. The remarkable consistency of these translocations implicates the dysregulation of CDK6 via translocation to IGK as a recurrent pathomechanism during the emergence of B-cell lymphoproliferative disorders.

Keywords: Genetics
Malignancy
Hematology
B-cell Neoplasia
Chromosomal Translocation
Monoclonal B-cell Lymphocytosis
Chronic Lymphocytic Leukemia
Non-Hodkin Lymphomas
PCR
CDK6
IGK
Advisor: Wang, Chen
Hybrid Organic / Inorganic Solar Cells Based On Electrodeposited ZnO Nanowire Arrays on ITO and AZO Cathodes

ZnO nanowire arrays (NWAs) and Al-doped ZnO (AZO) cathodes were applied in hybrid organic / inorganic solar cells for lower-cost solar energy. Parameters for the electrodeposition of ZnO NWAs and the fabrication of NWA-free baseline devices were systematically optimized using ITO as the cathodes. High efficiencies of up to 5.4% were achieved. Incorporation of the ZnO NWAs into the baseline devices significantly reduced their efficiencies due to possible shorting in the active layer. Devices fabricated using AZO cathodes were characterized. The AZO-based devices achieved efficiencies of up to ~4.8%, showing promising results for the application of AZO as an ITO alternative. Formation of numerous large nanoplatelets was observed during the electrodeposition of ZnO NWAs on AZO cathodes. The NWAs grown on AZO cathodes were also non-uniform. Future studies were proposed to address the issues with incorporation of ZnO NWAs in hybrid solar cells and their combination with AZO cathodes.

Keywords: ZnO Nanowire Arrays
Hybrid Organic / Inorganic Solar Cells
Advisor: Ruda, Harry E.
The Role of Adult Neurogenesis in Contextual Learning and Memory Interference

New neurons are continually produced throughout adult life in the dentate gyrus of the hippocampus, in a process termed adult neurogenesis. Although there is a significant effort in the literature to understand the functional significance of hippocampal neurogenesis, conflicting experimental reports have left the role of neurogenesis unclear. Recently, computational modelling studies have hypothesized that neurogenesis may play a role in allowing association between event and context to be formed in memory. By using a novel odour task and a raised plus maze task, our work demonstrates that the reduction of hippocampal neurogenesis using focal irradiation impairs the ability of animal subjects to utilize contextual information to learn interfering information. The result of this work provides experimental evidence of a unique role neurogenesis may play in learning and memory.

Keywords: Behaviour
Neurogenesis
Interference
Irradiation
Advisor: Wojtowicz, Jan Martin
Predictive Factors for Outcome in Patients having Surgery for Cervical Spondylotic Myelopathy.

PURPOSE: The objective was to determine if particular magnetic resonance, clinical and demographic findings were associated with functional status prior to surgery and predictive of functional outcomes at follow-up. RESULTS: The study included 65 consecutive CSM patients. The modified Japanese Orthopaedic Association Scale (mJOA) was used as the primary outcome measure. Higher baseline mJOA scores were associated with younger age, shorter duration of symptoms, fewer compressed segments and less severe cord compression. Better post-operative mJOA scores were associated with younger age, shorter duration of symptoms and higher baseline scores. Using multivariate analysis, baseline and follow-up mJOA scores adjusted for baseline mjOA score were best predicted by age. CONCLUSION: Age and clinical severity scores at admission can both provide valuable information. However, MR imaging features of the spinal cord before surgery cannot accurately predict the functional prognosis for patients with CSM and hence alternative imaging approaches may be required.

Keywords: cervical spondylotic myelopathy
magnetic resonance imaging
predictors
surgical outcomes
Advisor: Fehlings, Michael G.
Genetic Determinants of Plasma alpha-tocopherol

alpha-tocopherol is the most abundant form of vitamin E in human plasma and tissues. Inter-individual differences in plasma alpha-tocopherol concentration or its response to dietary alpha-tocopherol may be due, in part, to polymorphisms in vitamin E metabolism genes (alpha-tocopherol transfer protein (alpha-TTP), tocopherol associated protein (TAP) and CYP4F2). The thesis objectives were to determine whether common polymorphisms in the alpha-TTP (rs6994076 A>T), TAP (rs2072157 C>T and Arg11Lys) and CYP4F2 (Val433Met) genes influence plasma alpha-tocopherol concentration or modify the association between dietary and plasma alpha-tocopherol. Subjects (n=1248), 20 to 29 years from the Toronto Nutrigenomics and Health study completed a food frequency questionnaire. Fasting blood samples were used for genotyping and to measure plasma alpha-tocopherol concentration. The alpha-TTP and TAP Arg11Lys polymorphisms significantly altered plasma alpha-tocopherol. The alpha-TTP polymorphism only influenced plasma alpha-tocopherol in individuals not using supplements. None of the polymorphisms examined modified the plasma alpha-tocopherol response to dietary alpha-tocopherol.

Keywords: vitamin E
alpha-tocopherol
plasma
single nucleotide polymorphism
alpha-tocopherol transfer protein
alpha-TTP
tocopherol associated protein
TAP
CYP4F2
nutrition
genetics
nutrigenomics
Advisor: El-Sohemy, Ahmed
Characterization of Disease-causing Mutations in the Chloride-Proton Antiporter ClC-5

Mutations in the chloride-proton antiporter, ClC-5, cause Dent’s disease, a kidney disease defined by excessive loss of proteins in the urine. ClC-5 resides on early endosomal membranes in proximal tubule epithelial cells, where it facilitates protein receptor-mediated endocytosis. Loss-of-function mutations in ClC-5 produce proximal tubule defects in protein reabsorption. This study characterized an epithelial cell phenotype for nonsense ClC-5 mutations, R648X and R704X. Both ClC-5 mutants displayed defective biosynthesis, mistrafficking and ER localization. This study showed that ClC-5 mutations, R718X and C221R, which are also misprocessed and ER retained, are targeted for proteasomal degradation as a means to be efficiently eliminated from the ER. In addition, we have shown that a missense mutation in ClC- 5, C221R, causes a global conformational change in the antiporter, which likely reflects protein misfolding, as evident by enhanced susceptibility to trypsin proteolysis. We have characterized ClC-5 disease-causing mutations in an epithelial cell model of the proximal tubule.

Keywords: ClC-5
Dent's Disease
Advisor: Bear, Christine
Microfluidic Modeling of Cell Flow & Self-assembly of Gold Nanorods with Different Lengths

The thesis is divided into two parts: (1) microfluidic modeling of blood cell flow in constricted microvasculature and (2) the kinetic study of self-assembly of Au nanorods with different lengths. The passive mechanism of the flow of neutrophils was studied by using poly(dimethyl siloxane) microchannels with circular cross-sections as model blood vessels and agarose microgels as model cells. Their velocity and pressure profiles at various locations inside the microchannel with constrictions were studied as functions of (a) the initial velocity of the microgels, (b) the degree at which the channel-at-large tapered into the constriction, and (c) the size of microgels. Previously, our group proposed that the kinetics of self-assembly of Au nanorods resembles that of the reaction-controlled step-growth polymerization. To investigate factors that affect the reactivity of functional groups, self-assembly experiments were performed for nanorods with different lengths and their kinetics was analyzed.

Keywords: Microfluidics
Self-assembly
Nanochemistry
Step-growth polymerization
Modeling cell flow
Advisor: Kumacheva, Eugenia
Understanding the Regulation of HMGCR

Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate limiting enzyme of the mevalonate (MVA) pathway, and are also known to possess tumour-specific apoptotic effects. This tumour-specific statin-sensitivity can be defined on the basis of features such as dysregulation of the MVA pathway. We show that a subset of lung cancer cell lines undergo statin-induced apoptosis. We next address whether sensitivity is associated with HMGCR dysregulation at the level of post-translational modification. We focus on the key residue S872, which has been shown to be phosphorylated by AMP-activated protein kinase (AMPK) in vitro. We show that this site does not affect proliferation rate in two cell lines, and demonstrate that it significantly reduces anchorage independent growth in one cell system. In summary, we show that a subset of lung cancer cell lines are sensitive to statin-induced apoptosis and begin to understand whether HMGCR dysregulation may be a hallmark of statin-sensitivity.

Advisor: Penn, Linda Z.
Effect of Binder Content and Load History on the One-dimensional Compression of Williams Mine Cemented Paste Backfill

Large voids created by underground mining are backfilled to provide regional ground support. This thesis examines using conventional oedometer techniques and electromagnetic (EM) techniques to characterize consolidation and binder hydration in mine backfill so that EM monitoring can be used in the field to provide real-time feedback to operators to optimize the backfilling process. New techniques are given for interpreting the full range of deformation (initial compression, primary and secondary consolidation). Deformation due to initial compression is non-trivial and may have to be accounted for in numerical back-analyses of field case studies. EM parameters are sensitive to binder content, progress of hydration and loss of water caused by consolidation and binder hydration. The integrated interpretation of consolidation and EM behaviours has significant potential impact on real-time monitoring of mine backfill operations, and recommendations are made to advance the technique for this purpose.

Keywords: Civil Engineering
Mining
Compression behaviour
Cemented Paste Backfill
Mine tailings
consolidation test
Advisor: Grabinsky, Murray
Generation of a Murine Model for Renal Cell Carcinoma by Overexpression of HIF2α

Renal cell carcinoma (RCC) is the commonest urogenital tumor, characterized by increased expression of hypoxia inducible factors (HIFs). During normoxia, HIFα subunits are targeted for proteasomal degradation by the product of the von Hippel Lindau gene (pVHL). In RCC, mutations in the VHL gene allow the HIFα subunits to escape degradation and translocate to the nucleus where they activate transcription of their target genes. Although both HIF1α and HIF2α are upregulated in RCC, it has been suggested that HIF2α plays the dominant role. To further elucidate the function of HIF2α in RCC, we generated a transgenic mouse model that permits temporal stabilization of HIF2α in renal tubular cells. Induction of HIF2α results in the rapid development of renal cysts - a feature observed in RCC. Taken together, these results suggest that HIF2α is a key player in development of RCC and an excellent candidate target for therapy in this disorder.

Keywords: HIF2alpha
Hypoxia
Kidney Cancer
Transgenic Animal Model
Advisor: Quaggin, Susan E.
Expression of Podosomes and Small-conductance Ca2+-activated K+ Channels in Cultured Microglia

The presence of microglia at sites of CNS injury can potentially shift the balance between neuronal survival and death; however, the mechanisms regulating their mobilization to these sites are still poorly understood. Here I report that microglia express podosomes, short-lived, punctate organelles which adhere to and degrade extracellular matrix (ECM). Podosomes and related invadopodia of cancer cells have recently been the focus of much interest for their roles in migration and invasion. Microglial podosomes degraded ECM, providing impetus for further study of their function in microglia. Further, I report the Ca2+-activated SK3 channel as a novel component of the podosome core. While SK3 and SK4 channels are reported to play redundant roles in activated microglia (Kaushal et al., 2007; Schlichter et al., 2010), immunostaining work suggests that they are differentially regulated during microglial activation. Together, these results suggest unique functions for these channel subtypes in microglia.

Keywords: Microglia
podosomes
SK3
SK
Advisor: Schlichter, Lyanne C.
Investigating the Role of PHIP1 in Breast Cancer

PHIP1 is a novel downstream transcriptional co-regulator of insulin-like growth factor-I receptor (IGF-IR), a tyrosine kinase receptor that is often elevated and autophosphorylated in breast cancer. In this study, I show that PHIP1 is upregulated in MCF10A cells stably overexpressing IGF-IR signaling components and that knock-down of PHIP1 significantly inhibits breast cancer cell proliferation by inducing transcriptional upregulation of p21 and downregulation of cyclin D2. I also show that stable overexpression of PHIP1 in MCF10A cells can lead to its proteasomal degradation. Together, our data indicate that PHIP1 is implicated in breast cancer cell growth and suggest a number of avenues that await exciting discovery.

Keywords: IGF-IR
breast cancer
PHIP1
oncogenesis
Advisor: Rozakis-Adcock, Maria
The Glycemic Response Elicited by Oat β-glucan Solutions and Hard Gel Varying in Physiochemical Properties and Food Form

The ability of the soluble fibre (1->3)(1->4)-β-D-glucan to attenuate postprandial glycemic responses depends on its viscosity which, in turn, depends on molecular weight (MW) and dose. However, the effect of altering viscosity by changing solution volume is unknown. Furthermore, β-glucan solutions may form hard gels when left to age, but the effect of these gels on glycemic responses is unknown. Therefore, the effects of varying the MW and volume of β-glucan solutions and hard gels, on glycemic responses were determined. The results showed that glycemic responses were reduced by increasing viscosity by increasing MW but not by reducing solution volume. Although β-glucan gels reduced the rate of glucose diffusion in vitro, they had no effect on glycemic responses in vivo. Thus, changing solution viscosity through changes in volume does not alter the effect of β-glucan on glycemic response, and β-glucan gels are ineffective at attenuating in vivo glycemic responses.

Keywords: Nutritional Sciences
Food Chemistry
Cereal Chemistry
Glycemic Response
Beta-D-Glucan
Viscous Soluble Fibre
β-D-Glucan
Food Hydrocolloids
Molecular Weight
Solution Volume
Food Gels
Glycemic Control
β-Glucan
Oats
Oat Fibre
Dietary Fibre
Human Nutrition
Cereal Sciences
Food Science
Glycemic Index
Advisor: Wolever, Thomas M. S.
The Effects of Continuous Positive Airway Pressure on the Work of Breathing at Rest and during Exercise

Ventilation may limit exercise. Wearing a gas mask may further compromise ventilation. Continuous positive airway pressure (CPAP) improves ventilation by reducing airway resistance and thus the work of breathing. We investigated the effects of wearing a gas mask with and without CPAP on the work of breathing (WOB) during resting and exercise conditions to determine (a) whether wearing a gas mask increases the WOB and (b) whether the application of CPAP to a gas mask will mitigate (reduce) said increase to the WOB. Ten healthy males completed two test protocols with three stages each, and in three mask conditions. Physiological and dyspnea parameters were measured. Wearing a gas mask increased the metabolic cost and work of breathing. When the portable CPAP device was applied, there was no change in the calculated work of breathing, but metabolic cost of breathing was significantly reduced. CPAP also significantly reduced the sensation of dyspnea.

Keywords: Work of Breathing
CPAP
Exercise
Advisor: Fisher, Joseph A.
Roles of Irx3/5 in Mouse Hindlimb Development

Iroquois (Irx) homeobox genes have important and redundant functions during embryogenesis. Irx3/5 double knock out (Irx3/5 KO) mouse embryos exhibit severe hindlimb phenotypes. In these mutant hindlimbs, digit 1 and tibia are absent, moreover femur and pelvis are hypoplastic. Here, we demonstrate that Irx3/5 are expressed in the hindlimb field prior to limb bud initiation, and are required at this early stage for the pattern formation along the anteroposterior axis. Their early function is involved in prepatterning and positioning the Shh expression domain. In addition, Irx3/5 KO mutant hindlimb buds have a mild outgrowth defect and increased cell death at early stages of limb development, which may explain the small hindlimb bud size in these mutant embryos. To examine whether Irx3/5-expressing cells are the origin of lost and affected structures in Irx3/5 KO mutant hindlimbs, targeting vectors with Cre genes inserted into the Irx5 locus have been generated.

Keywords: Iroquois genes
hindlimb development
prepatterning
mouse
Advisor: Hui, Chi-chung
Hopyan, Sevan