VictorJuiz/thesis huggingface dataset:
Microfluidics for Measuring Solubility and Diffusion Coefficient of Solvent in Bitumen
Keywords: Bitumen
Diffusion coefficient
Hydrocarbon solvent
Microfluidic
Solubility

In this thesis, a microfluidic approach is developed to determine both the solubility and diffusivity of propane in the Athabasca bitumen at a range of reservoir-relevant pressures and temperatures. The presented microfluidic approach offers advantages over the conventional methods including fast quantification, small volume requirement, and ease of operation at high temperatures and pressures. The fabricated glass-silicon microfluidic chip contains a Pressure â Volume â Temperature (PVT) microchannel with full temperature and pressure control, connected to both solvent and bitumen supply. The cross-sectional area of the bitumen supply channel was only 2.5% that of the cell, approximating a closed PVT system. One-dimensional oil swelling due to solvent diffusion was captured consecutively using fluorescence microscopy and the solvent solubility and diffusion coefficient were then determined through image analysis and established mathematical models. The final results are in strong agreement with the available published data obtained by conventional methods.
Patterns of Methadone Use and Perinatal Outcomes Among Pregnant Women in Ontario
Keywords: Addiction
Methadone
Opioids
Pregnancy

Methadone maintenance therapy (MMT) is the standard treatment for opioids use disorder during pregnancy as it minimizes opioid cravings and withdrawal symptoms without causing sedation or euphoria. We conducted a population-based cohort study among Ontario public drug beneficiaries who used MMT during pregnancy to determine their timing of initiation, number of gaps in therapy during pregnancy, maternal characteristics, and rates of perinatal outcomes. Among 1,842 women, the median age was 27 years, 71.2% (N=1,311) were multiparous, 87.6% (N=1,614) initiated MMT before conception, and 61.7% (N=1,137) of women had zero gaps in MMT during pregnancy. 22.2% of infants were small for gestational age, 17.5% were preterm, and 5.9% had a congenital anomaly. These outcomes generally did not differ based on number of gaps or timing of initiation. However, the cohort's outcome rates were higher compared to general populations, suggesting that this is an at-risk population in need of increased clinical support.
Advanced Multifunctional Micro-Textured Thermoplastic Elastomeric Fiber Composites
Keywords: 3D Printing
Abrasion
Fiber Composites
Friction
Hydrophobicity

Micro-Textured Composite surfaces are becoming increasingly useful in several applications such as friction, hydrophobicity and abrasion resistance. This work focuses on development of a novel surface texturing approach using fiber de-bonding and pull-out method that would not require any additional post texturing process. First, several different types of fibers are studied with two different thermoplastic matrices (Thermoplastic polyurethane and Styrene-Butadiene-Styrene). Their friction properties on wet ice as well as their hydrophobic behaviors are studied. This is followed by conducting an abrasion study of these composite surfaces to determine the abrasion resistance of these textured surfaces and relate to their microtextured surface properties. After development and characterization of these textured composite surfaces, a more faster approach of fabricating aligned fiber composites using fused deposition modelling is developed. To verify fiber alignment with the new developed rapid prototyping methodology, the new fabricated composite surfaces are textured and their surface properties are characterized.
Dynamic Mechanical Properties of Short Fiber Reinforced Polymers
Keywords: Composites
Mechanical Properties
Polymer
Viscoelasticity

Recently there has been a drive to replace traditional engineering materials with polymeric solutions. Fiber reinforced polymers offer combine the inherent benefits of polymers such as light weight and anti-corrosion with high strength and stiffness to weight ratios. Polymers are highly viscoelastic meaning they have both elastic, solid, and viscous, fluid like behavior and their mechanical properties are time dependent. Dynamic mechanical analysis is a useful tool in measuring the viscoelastic behavior of materials, and glass transition in response to cyclic loading cycles. Each chapter in this work studies the dynamic mechanical behavior of a different class of polymer, from polyurethane thermosetting rubber, to polyester based thermoplastic elastomer, to high performance polyamide thermoplastic. In each case, novel composite materials have been developed and characterized by reinforcement with selective fibers which was found to significantly enhance the mechanical and thermal properties of the pure polymer.
Synthesis of Isocyanates from CO2 and Amines under Mild Conditions
Keywords: aryl amine
carbon dioxide
isocyanate

A mild and metal-free synthesis of unsymmetrical ureas and carbamates from amine and atmospheric carbon dioxide has been developed. The carbamic acid intermediates derived from aryl amines and CO2 in the presence of DBU were subjected to the dehydrating action of activated sulfonium reagents commonly used in Swern oxidations. The resulting isocyanate was detected by in-situ React IR before being quenched with amines and alcohols to afford ureas and carbamates. Diisocyanates relevant to the polyurethane industry, such as 4,4'-methylene diphenyl diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI), have also been synthesized in good yields through the mild dehydration of the corresponding dicarbamic acids. The present thesis also describes the preliminary application of this mild dehydration in synthesizing hydantoin derivatives from amino amides and CO2.
Assembly of the Human R2TP Chaperone Complex
Keywords: Pih1
PIH1D1
R2TP
RPAP3
RUVBL
Rvb

The Human R2TP complex is composed of hRvb1, hRvb2, RPAP3 and hPih1, and it is required for snoRNP biogenesis, PIKK signaling and RNA polymerase II assembly. Despite its important functions, much information on the structure of the human R2TP complex is still not available. In order to build up a foundation for the structural and functional studies of the human R2TP complex, I endeavored to reconstitute the complex in vitro. I successfully purified the human R2TP proteins, studied the interactions amongst these proteins, and attempted the complex reconstitution using different methods. Amongst the R2TP proteins, hRvb1 and hRvb2 could oligomerize together to form the hRvb1/hRvb2 complex, and RPAP3 and hPih1 could also interact to form the RPAP3/hPih1 complex. However, the interaction across the two sub-complexes of R2TP seemed to be rather weak, suggesting the successful formation of the complete R2TP complex might require help from extra assembly factors.
Cbl-b deficient CD4+ T cells mediate resistance against regulatory T cells through IL-2 overproduction
Keywords: cytokine
immunity
immunosuppression
inflammation
T cell
Treg

Regulatory T cells play crucial roles in health and diseases through their immunosuppressive properties. In particular, Treg cells in the tumor microenvironment are known to restrict anti-tumor immune response and therefore understanding mechanisms of resistance to Treg-mediated immunosuppression serves as an attractive therapeutic avenue. E3 ubiquitin ligase Cbl-b is a regulator of multiple TCR signaling pathways, and has demonstrated its potential in rendering T cells impartial to the suppressive signals of Treg cells through regulating cytokines. This study specifically explored cellular mechanisms associated with Cbl-b KO CD4+Foxp3- effector T cell resistance against Treg cells. Cbl-b KO CD4+Foxp3 T cells hyper-produced IL-2 and together with IL-2RÎą upregulation served as an important mechanism to escape suppression by Treg cells. Overall, the study offers insights into the potential development of CD4+ T cells resistant to suppression by regulatory T cells.
Socialist Industrialization and Railway Sector Development in the Early PRC
Keywords: China
Colonialism and postcolonial theory
PRC history
Railway development
Socialist industrialization

My thesis focuses on national industrialization in the early decades of the Peopleâ s Republic of China (PRC). The industrialization project connected the following: histories and impacts of Western imperialism, the distinctive form of Third World socialism, and the importance of economic and technological development to the early PRC. I explore the above set of connections in order to answer my motivating question: What is particularly socialist about the early PRCâ s industrialization project? I begin with histories and plans. Western depictions of state planned economies rely on tropes of irrationality. I retrieve the logical content of early PRC plans by piecing together historical data, the text of plans, and narratives from early PRC leaders and planners. I then turn to the formulation and implementation of state plans. I trace these processes through events in the state railway sectorâ a system that evolved in tandem with the project of early PRC industrialization.
Phylogenetic and Experimental Evidence for an Evolutionary Precursor to Male Colouration in Poeciliid Fishes and Their Relatives
Keywords: Behaviour
Experiments
Fishes
Phylogenetic Comparative Methods
Sexual Selection

In many animals, phenotypic diversity in males originates through sexual selection. However, the evolutionary origins of female preferences are unclear. The sensory bias hypothesis suggests female preferences can originate as a byproduct of natural selection operating on sensory systems in non-sexual contexts, like foraging. Despite over 25 years of investigation, fundamental tenets of the sensory bias hypothesis remain unresolved. We explicitly test one of these tenets: the historical dependency of male traits on pre-existing biases in females. We marry phylogenetic comparative methods and behavioural experiments to test for this dependency in poeciliids and related fishes. Our results demonstrate that female biases for long-wavelength colours drove the evolution of long-wavelength colouration in males. In addition to demonstrating this dependency, our study suggests (i) behaviour can be phylogenetically conserved, and (ii) natural selection may be the ultimate explanation for a tremendous amount of variation that has classically been attributed to sexual selection.
Quantum Transport Studies of InAs Based Nanowire Devices
Keywords: Ballistic
InAs
Nanowire
Quantum

Experiments and analysis reported in this thesis advance the understanding of quantum transport in nanowire transistors. Indium Arsenide nanowires grown by molecular beam epitaxy were incorporated into numerous back-gated field effect transistors and electronic measurements confirm electron transport is occurring in a regime where ballistic transmission and quantum confinement effects are significant. Quantum interference phenomena are investigated through electrostatic manipulation of interface charge configurations and interference quenching is demonstrated in a nanowire device. Elimination of interference distortions reveal perfect quantization of the conductance and provide direct insight into the one-dimensional quantum-electronic bandstructure which displays strong divergence from cylindrical hard-wall confinement. Numerical simulations investigating morphological variations demonstrate a strong influence on electronic sub-band structure, prompting characterization of the cross-sectional morphology via focused ion beam micro-sampling and transmission electron microscopy. Adoption of hard-wall confinement potentials consistent with the characterized morphology indicates significant electrostatic influence of interface charges on the sub-band structure.
Zinc Mediated Synthesis of Cyclopropylamines
Keywords: Cyclopropylamines
Zinc Homoenolate

The cyclopropylamine motif is often found in both natural and pharmaceutical compounds. Our group has recently developed a synthesis of trans-cyclopropylamines using electrophilic zinc homoenolate intermediates. This thesis describes the attempted extension of this concept to an intramolecular version of this transformation to yield cyclopropanated heterocycles. Despite the successful preparation of the linear precursor for the synthesis of 2,3-methanopyrrolidine, cyclization did not result in any desired product. The second part of this thesis describes a one-pot synthesis of trans-cyclopropylamines from readily available a-chloroaldehydes and amines. Zinc homoenolate intermediates have been reported in the synthesis of cyclopropanols from a-chloroaldehydes, as well as being the key intermediate in our synthesis of trans-cyclopropylamines. Hence, combining both processes would allow the development of a versatile synthetic method to access trans-cyclopropylamines. While products were obtained in excellent yields, diastereomeric ratios remained low, which led us to speculate that this reaction is under thermodynamic control.
Systematic Quantification of Superficial Blood Flow in Near Infrared Spectroscopy Brain Computer Interfaces in a Pediatric Context
Keywords: Brain-computer interfaces
Near-infrared spectroscopy
pediatric
superficial blood flow
verbal fluency task

Brain-computer interfaces (BCIs) have been developed as an access pathway for individuals who present as locked-in, but only in adults. Near-infrared spectroscopy (NIRS) signals have been suspected to be influenced by superficial blood flow signals, suggesting that its removal may result in better BCI classification accuracy. Seven typically developing children aged 8-12 participated in three offline sessions in order to assess the suitability of NIRS-BCIs in children, and to examine the effect of superficial blood flow on classification accuracy. Superficial flow was induced using a five-minute bicycle task, and the deep signal was extracted using the multi-distance independent component analysis method. Our results yielded an average classification accuracy of 76.7Âą8.3% with six participants achieving the 70% threshold for an effective BCI. We demonstrated that the induced superficial flow was able to significantly affect BCI classification accuracy, but removal of the superficial signal offered no or limited benefit in children.
Attention Biases Among Preschool-Aged Children Exposed to Domestic Violence: An Eye-tracking Study
Keywords: Attention biases
Child development
Child psychopathology
Domestic violence

The purpose of this study was to investigate whether preschool-aged children exposed to domestic violence (DV) are more vigilant of threatening (i.e., angry faces) versus neutral faces relative to non-exposed children, and whether such vigilance relates to child psychopathology. Preschool-aged children (18 to 60 months-of-age) exposed to DV (as substantiated by child protective services) and their mothers (n=13), as well as typically developing children and their mothers (non-exposed group, n=25), participated in this study. Children completed an eye-tracking task to assess their attention to face stimuli (e.g., angry-neutral, sad-neutral, and happy-neutral face pairings). Mothers completed the Ages and Stages Questionnaire â Social and Emotional (ASQ-SE-2; Squires, Bricker Twombly, 2015). Results show that young, DV-exposed children fixated on faces for a shorter duration relative to non-exposed children, and that vigilance to angry faces is associated with more behavioural and emotional problems. Practical applications resulting from attentional bias research are discussed.
A Novel EEG-BCI Dependent on Discrimination of Imagined Stimuli in Visual Field Quadrants
Keywords: BCI
EEG
imagery
visuospatial

Brain computer interfaces (BCIs) can provide individuals with severe motor disorders a means of communication. This study aimed to determine whether visuospatial imagery could be used to signify intent in an electroencephalography (EEG)-based BCI. Eighteen healthy participants imagined stimuli in visual field quadrants while EEG was collected. A subset of participants used visuospatial imagery to control a character’s movement in four directions. Classifying rest against non-specific visuospatial imagery attained accuracies of 77±11.4%. Six participants exceeded chance when discriminating imagery in diagonally-opposing quadrants. These six could be predicted using a regression model that combined visuospatial perception and fatigue scores. The 4-class navigation accuracy was 48.3±18.8% (max 85%). Imagery in one hemifield corresponded to significant increases in alpha spindles in ipsilateral visual cortical regions. While further improvement is necessary to make the paradigm generalizable, visuospatial imagery shows promise for becoming a useful system for individuals in need of a BCI access technology.
Predictors of Hospital Readmission after Trans-Catheter Aortic Valve Implantation in Ontario
Keywords: aortic stenosis
hospital readmission
TAVI

Trans-catheter aortic valve implantation (TAVI) is the standard of care for treatment of aortic stenosis in patients deemed too high risk for surgical valve replacement. However, recent data have shown that patients who undergo TAVI have exceedingly high rates of hospital readmission. Our objectives were to determine the predictors of readmission while seeking to identify any modifiable factors. We conducted a retrospective observational cohort study based on abstraction of detailed clinical data that included 937 patients discharged alive after TAVI. Readmission occurred in 17% of patients within 30 days and 49% within 1 year. Heart failure was the most common cause of readmission. Bleeding was also a major cause of readmission and many covariates related to bleeding were associated with a higher hazard of readmission. Transition of care factors were not associated with reduced readmission. These results suggest that quality improvement efforts directed at optimal heart failure management and bleeding avoidance, may reduce readmission.
Optical and Structural Characterization of Hydrogenated Aluminium Nitride Thin-films Synthesized at Low Temperature
Keywords: Hydrogenated Aluminium Nitride
Low Temperature Synthesis
Optical and Structural Characterization
Spectrally Selective Coatings

A fundamental study of the optical and structural properties of hydrogenated aluminium nitride (AlN:H) films is presented. It is shown that incorporation of hydrogen within aluminium nitride (AlN) enables inherent optical tunability and leads to enhancement in its optical transmittance. It is revealed through microscopy studies (SEM, AFM and TEM) that the AlN:H films have an amorphous-nanocrystalline character, undergo non-columnar growth, and have reduced surface roughness, and feature size. Examination of the infrared vibrational modes indicate enhancement in chemical stability and robustness of the AlN:H films. Optical tunability coupled with excellent physical, structural and chemical properties of the AlN:H films enabled its successful integration in spectrally selective coatings (SSCs) wherein these multilayer stacks are synthesized with the fewest layers in comparison to the state-of-the-art and have been experimentally demonstrated to provide optimal solar energy control and rapid active uniform heating with inherent stability against degradation from ambient moisture and oxygen.
The Development of In Vivo and Microcoil NMR: Towards Single Egg Toxicity Screening
Keywords: ecotoxicology
in vivo NMR
microcoil NMR
Nuclear Magnetic Resonance
single cell
single egg

An objective in ecology is to understand an organism’s response (e.g. Daphnia magna) to changing environmental conditions. Under unfavorable conditions, D. magna’s dormant eggs are stored in aquatic sediments, where exposure to toxins can lead to population decimation. A single egg has a small volume (~4 nL), making them challenging to study via conventional Nuclear Magnetic Resonance (NMR). The static nature of eggs allows for their localization over planar microcoils and an increase in signal-to-noise ratio is observed relative to larger coils. This thesis applies a range of planar microcoils (
Protein Kinase C Î´ Regulates Cellular Protrusions and Filamentous Actin Organization during Drosophila Border Cell Migration
Keywords: Border cell cluster
Cell migration
Cellular protrusions
Drosophila
F-actin
Protein Kinase C Î´

The migrating border cell cluster (BCC) of Drosophila ovarian follicles is an excellent model for studying collective cell migration. My project aimed at gaining mechanistic insight into the function of the serine/threonine kinase Protein Kinase C δ (PKCδ) in the migrating BCC. Analysis of mosaic BCCs containing PKCδ mutant or PKCδ-overexpressing cells indicates that normal PKCδ expression is important for a cell in the cluster to lead migration. Increasing or eliminating PKCδ caused a reduction of non-muscle myosin II in cellular protrusions and along the cell cortices of the BCC perimeter. Tagged transgenic PKCδ enriched in the leading protrusion in a complementary distribution with F-actin, where it appears to antagonize F-actin induced by the actin elongation factor Enabled. Inhibition of Enabled activity suppresses the effects of loss of PKCδ on F-actin organization. These findings suggest that PKCδ is a negative regulator of F-actin and functions in an Enabled-dependent process.
Development of an Anthropomorphic Dynamic Heart Phantom
Keywords: Biomedical Phantoms
CT Attenuation
Mechanical Properties
Myocardial Tissue

Dynamic anthropomorphic heart phantoms are a developing technology which offer a methodology for optimizing current computed tomography coronary angiography techniques. This work focuses on the development of a myocardial tissue analogue material that can be utilized as a synthetic heart for Toronto General Hospitals(TGH) current dynamic phantom. First, the mechanical properties of myocardial tissue are studied to determine the static (youngâ s modulus) and viscoelastic (storage/loss modulus, tan delta) properties of the tissue. A dioctyl phthalate and poly(vinyl) chloride material is then developed which mimics the obtained properties and the computed tomography(CT) attenuation of myocardium. The material is then utilized to create a heart/coronary artery model which can be integrated with the phantom in a cardiac CT simulation scan. Through this study it is seen that the phantom provides: a visual simulation to myocardium, motion profiles of the coronary arteries and hearts, and can be used as a plaque analysis tool.
Assessing Physical Activity, Mental Health, and Stress among International Students at the University of Toronto.
Keywords: International Students
Mental Health
Mental Illness
Physical Activity
Stress

Physical activity is vital for maintaining the health of students on campus. However, there is a lack of research examining International students (IntS) mental and physical activity (PA) needs. The purpose of this study was to examine the relationship between PA and mental health within an acculturation framework; and to explore IntS experiences with PA and mental health. Two studies were used to address the aims of this study. In study one, secondary data from domestic (n = 4035) and IntS (n = 605) were analyzed. PA mediated the association between stress and mental health but it did not mediate the association between stress and mental illness. In study two, interviews were conducted with 12 IntS, and analyzed using thematic analysis. Results indicate that IntS are facing several cross-cultural, adaptation, and organizational challenges. Higher institutions must continue to explore IntS needs and barriers in order to support them effectively.