VictorJuiz/thesis huggingface dataset:
The Architectural Optimization of Stretch-formed Ceramic-aluminum Microtruss Composites

Microtruss cellular materials have large internal surface areas and small cross-sectional strut dimensions, permitting surface modification to substantially enhance their mechanical performance. For instance, a ~400% increase in compressive strength with virtually no weight penalty can be induced by a hard anodized Al2O3 ceramic coating of only ~50 µm thickness. The present study seeks the optimal architecture of these composites by exploring three research challenges: architecture and degree of forming are interdependent due to stretch-forming, architecture and the material properties are interdependent due to work-hardening, and ceramic structural coatings add design complexity. Theoretical predictions and architectural optimizations demonstrated a potential weight reduction of ~3% to ~60% through the increase of internal truss angle for both annealed and work-hardened microtruss cores. While further validation is needed, experimental evidence in this study suggested the collapse in ceramic-aluminum microtruss composites could be considered as a mixture of composite strut global buckling and oxide local shell buckling mechanisms.

Keywords: Architectural optimization
Stretch forming
Work hardening
Cellular materials
Microtruss composites
Ceramic-Aluminum hybrids
Anodizing
Analytical modelling
Compressive strength
Buckling
Advisor: Hibbard, Glenn D.
Towards Automated Nanomanipulation under Scanning Electron Microscopy

Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial’s properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires’ electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.

Keywords: Nanorobotics
Nanomanipulation
Advisor: Sun, Yu
Sufficient Conditions for Output Regulation on Metric and Banach Spaces - A Set-theoretic Approach

Output regulation problems are a class of problems that has high importance in systems control engineering. The solutions of such problems generally involve the design of an internal model based controller with error feedback structure that can also provide stability to the closed-loop system. Most of previous studies of such problems, however, are based on dynamical systems described by di erential equations for continuous-time and by di erence equations for discrete-time on the space of Rn. Few results have been obtained for dynamical systems with more abstract descriptions on sets with more general topologies. In this thesis, we use a set-theoretic approach with commutative diagrams to describe a dynamical system and its properties. Output regulation problems will also be de ned based on such dynamical systems. We will present su cient conditions for output regulation problems on complete metric spaces and Banach spaces.

Keywords: Dynamical Systems
Output Regulation
Advisor: Wonham, Murray
Mating of Starlike Quadratics

The bounded Fatou components for certain quadratic polynomials are attached to each other at the boundary and form chain-like structures called ``bubble rays". In the context of mating quadratic polynomials, these bubble rays can serve as a replacement for external rays. The main objective of this thesis is to apply this idea to the mating of starlike quadratics.

Keywords: Complex Dynamic
Mating Polynomials
Advisor: Yampolsky, Michael
Generating Inducible Vector Systems for Controlling Pluripotent Stem Cell Fate

Transgenic manipulation of exogenous and endogenous gene expression in human embryonic stem cells (hESCs) is a powerful approach to decipher the genetic pathways dictating their developmental fate. Presently used genetic tools face limitations including leakiness in inducibility of expression, epigenetic silencing in long-term cell culture, low genomic integration efficiencies, small genetic cargo limit and lack of high-throughput cloning capabilities. To overcome these limitations, I have constructed R4-Integrase and piggyBac transposon genetic vector systems for stable transgene overexpression and knockdown in hESCs. Preliminary functional testing of the piggyBac vector system in HEK 293T and hESCs demonstrated vector inducibility as well as successful overexpression and knockdown of pluripotency factor OCT4. Concurrently, a cost-effective and high efficiency method for chemical transfection of hESCs was developed. Exogenous overexpression and knockdown of transcription factors in hESCs will aid in the elucidation of gene regulatory networks controlling pluripotency and developmental fate.

Keywords: human embryonic stem cell
piggyBac
R4-Integrase
Advisor: Stanford, William L.
Modeling the Effective Thermal Conductivity of an Anisotropic and Heterogeneous Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer

In this thesis, two numerical modeling methods are used to investigate the thermal conductivity of the polymer electrolyte membrane (PEM) fuel cell gas diffusion layer (GDL). First, an analytical model is used to study the through-plane thermal conductivity from representative physical GDL models informed by microscale computed tomography imaging of four commercially available GDL materials. The effect of the heterogeneity of the through-plane porosity of the GDL and polytetrafluoroethylene (PTFE) treatment is studied and it is noted that the high porosity surface transition regions have a dominating effect over the addition of PTFE in impacting the overall thermal conductivity. Next, the lattice Boltzmann method (LBM) is employed to study both the in-plane and through-plane thermal conductivity of stochastic numerically generated GDL modeling domains. The effect of GDL compression, binder content, PTFE treatment, addition of a microporous layer (MPL), heterogeneous porosity distributions, and water saturation on the thermal conductivity are investigated.

Keywords: fuel cell
lattice Boltzmann modeling
Advisor: Bazylak, Aimy
Interactions of Cationic Antimicrobial Peptides with Bacterial Membranes and Biofilms

Cationic antimicrobial peptides (CAPs) offer a viable alternative to conventional antibiotics as they physically disrupt the bacterial membranes, leading to cell lysis and death. However, colonized bacteria often form “biofilms” – characterized by the overproduction of exopolysaccharides - that restrict the penetration of antibiotics; successful antimicrobial agents must evade this exopolysaccharide ‘matrix’ to reach the bacterial membrane. Since the Pseudomonas aeruginosa biofilm alginate traps CAPs by forming peptide-alginate complexes, the aim of this thesis is to better understand the mechanisms of interaction of CAPs with bacterial membranes and biofilm alginate. Using a series of CAPs designed in our lab derived from the sequence KKKKKK-AAFAAWAAFAA-NH2, we found that hydrophobicity, charge distribution, and amino acid composition of CAPs play important roles in their membrane disruptive power, bioactivities, alginate-binding and alginate-diffusion abilities. These findings suggest routes to an optimal balance of factors in CAP design to allow both biofilm penetration and bacterial membrane destruction.

Keywords: antimicrobial peptides
biofilms
Advisor: Deber, Charles M.
Protective Coatings of Y2O3 and CeO2 on Porous Stainless Steel Supports for Use in Intermediate Temperature Metal-supported Solid Oxide Fuel Cells

With increasing attention paid to metal-supported SOFCs recently, metal supports have become important factors in the performance of the cells. The formation of surface oxides and the poisoning of Cr from Cr2O3-forming metal supports often result in the degradation of the cells. However, few studies have focused on developing oxidation resistance and decreasing Cr migration from porous alloys in intermediate temperature metal-supported SOFCs. In this work, Y2O3 and CeO2 coatings were applied to porous AISI 430 stainless steels by sol-gel dip coating. Phases and microstructures of the coatings on the porous metal supports were characterized by XRD and SEM with EDS, respectively. The effects of the coatings on oxidation resistance of the supports were evaluated by cyclic oxidation testing. Electrical and electrochemical properties of LSCF-SDC cathodes and symmetrical cells deposited on the Y2O3-protected metal supports were also investigated. The issue of Cr depletion of the supports was also discussed.

Keywords: coatings
metal supports
solid oxide fuel cells
sol-gel
reactive elements
Advisor: Kesler, Olivera
A Novel Pathway for Enhanced Metabolic Capacities Underlies the Neuroprotective Actions of Teneurin C-Terminal Associated Peptide (TCAP)-1

Teneurin C-terminal Associated Peptide (TCAP)-1 is postulated to play a critical role in cellular defense mechanisms as it is highly neuroprotective against alkalotic and hypoxic stress. Optimization of metabolic pathways is recognized as an essential survival tactic by alleviating energy deficits and meeting the demands to cope with the stressors. The aim of this research was to delineate the mechanism through which TCAP-1 confers protection. My findings show that TCAP-1 increases the overall expression of GLUT1 and enhances overall expression and membrane localization of GLUT3. With respect to metabolic parameters, chronic TCAP-1 application led to increased intracellular [ATP] with decreased intracellular [lactate], both in a dose-dependent manner, but did not alter tumourgenic glycolytic enzyme expression or mitochondrially associated apoptotic protein expression. Contrastingly, acute TCAP-1 led to decreased intracellular [ATP]. Indicative of increased cellular ATP production and physiological energy expenditure, TCAP-1 reduced serum insulin levels and subcutaneous adipocyte size in vivo.

Keywords: Glucose
Apoptosis
Stress
Neuroendocrinology
Protection
Metabolism
ATP
Lactate
GLUT
Adipose
Leptin
Insulin
Glycolysis
Oxidation
TCAP-1
TCAP
Teneurin C-terminal Associated Peptide
Advisor: Lovejoy, David A.
Multi-antenna Relay Beamforming with Per-antenna Power Constraints

Multi-antenna relay beamforming is a promising candidate in the next generation wireless communication systems. The assumption of sum power constraint at the relay in previous work is often unrealistic in practice, since each antenna of the relay is limited by its own front-end power amplifier and thus has its own individual power constraint. In this thesis, given per-antenna power constraints, we obtain the semi-closed form solution for the optimal relay beamforming design in the two-hop amplify-and-forward relay beamforming and establish its duality with the point-to-point single-input multiple-output (SIMO) beamforming system. Simulation results show that the per-antenna power constraint case has much lower per-antenna peak power and much smaller variance of per-antenna power usage than the sum-power constraint case. A heuristic iterative algorithm to minimize the total power of relay network is proposed.

Keywords: Wireless communications
Electrical Engineering
Multi-antenna Relay Beamforming
Per-Antenna Power Constraints
Power minimization
SNR maximization
Sum power constraints
Advisor: Liang, Ben
Dong, Min
Validation of Point and Pressure Loading Models for Simply Supported Composite Sandwich Beams

Stiffness and strength models are derived for simply supported composite sandwich panels comprised of fibre-reinforced face sheets and polymer cores subject to symmetric four point bending and uniformly distributed loading. Optimal trajectories for minimum mass design are calculated using the models and situated on failure mechanism maps. A stiffness constraint is also derived to omit beam designs of excessive compliance. Analytical models were validated through an extensive series of experiments, considering beams comprised of GFRP face sheets with ROHACELL 51-IG and extruded polystyrene (EPS) polymer cores. An alternate loading fixture was used to simulate uniform pressure loads. In general, experiments were able to validate most analytical expressions for a range of experimental conditions. Though the predictions worked well with most beam cases, analytical models were noted to become unreliable for short or slender beams.

Keywords: composite
sandwich
four point bending
pressure
simply supported
failure mechanism map
Advisor: Steeves, Craig A.
Adjusting Expectations of Scale Based on Limitations of Supply: A Review of the Case for a Forest Bioenergy Strategy that Prioritizes Decentralization, Efficiency, and Integration

The limitations of renewable energy technologies require that pathways are carefully chosen such that renewable resources are used most effectively in addressing modern energy challenges. Optimized decision-making is particularly challenging for the forest bioenergy sector because of the multitude of potential pathways and because profit is highly sensitive to biomass procurement costs. I assessed energy wood recovery and procurement costs during semi-mechanized selection operations in the tolerant hardwood forests of Ontario. Logging contractors were able to recover unmerchantable sections of branches normally discarded during conventional operations, amounting to 1.3 to 2.7 dry tonnes of additional biomass per hectare. Supply chain scenarios are used to show that the biomass can be brought to market at a cost similar to mechanized operations. The need for prioritization of decentralization, efficiency, and integration with the value-added forest sector is discussed with reference to the relative scarcity and high cost of the forest resource.

Keywords: energy policy
forestry
forest policy
bioenergy
climate change
forest engineering
renewable energy
bio-heat
Advisor: Caspersen, John
MeCP2 Deficiency is Sufficient to Disrupt Daily Rhythmic Behaviours in Mice

Mutations in the X-linked gene encoding Methyl-CpG-binding protein 2 (MECP2) cause the neurodevelopmental disorder Rett syndrome, a common genetic cause of mental retardation in females. Although alterations in performance of MeCP2-deficient mice in specific behavioural tasks have been documented, it remains unclear if, and to what degree, MeCP2 dysfunction affects patterns of periodic behavioural and electroencephalographic activity. To address this, we monitored daily rhythmic patterns of core body temperature, gross motor activity, and cortical delta power from MeCP2-deficient mice and correlated it against regional MeCP2 expression levels. Our results show that normal daily rhythmic behavioural patterning of delta wave activity, body temperature and mobility are disrupted in these mice. Moreover, MeCP2-deficient mice displayed lower average core body temperature and significantly greater body temperature fluctuation than wild-type female mice. Finally, we also found that epileptiform discharge activity in MeCP2-deficient mice is more predominant during times of behavioural activity compared to inactivity.

Keywords: Rett Syndrome
Electroencephalography
Epilepsy
Thermoregulation
Delta Rhythm
Telemetry
Methyl DNA-Binding Factor
Mutant Mice
MeCP2 Expression
Phenotypic Behaviour
Advisor: Eubanks, James
Synthesis of a Novel Acyl Phosphate Cross-linker and its Modification of Hemoglobin

Hemoglobin-based oxygen carriers (HBOCs) are of great interest for their potential as a safer alternative to blood transfusions. To overcome the vasoactivity associated with small HBOCs, our group is interested in connecting two hemoglobin tetramers together, forming “bis-tetramers”. Bis-tetramers have previously been synthesized by our group, but yield and purity of the resulting solutions have been low and hindered their usefulness for trials. A new cross-linker was designed in an attempt to improve yield. This thesis describes the synthesis of an acyl phosphate cross-linker N-[bis(sodium methyl phosphate)isophthalyl]-4-azidomethylbenzoate (5), its modification of hemoglobin and subsequent purification attempts of the resulting solution. Cross-linker 5 was found to be selective to β-β-crosslinking and produced singly modified subunits as byproducts. Attempts to purify the resulting reaction mixture by heating resulted in the decomposition of the azide group on the cross-linker, which was critical for the coupling step. Efforts to overcome this problem were unsuccessful.

Keywords: hemoglobin
HBOCs
Advisor: Kluger, Ronald
Peripheral Muscle Strength, Functional Exercise Capacity and Physical Activity Before and After Lung Transplantation

Little is known about the early recovery of functional outcomes in the lung transplant population. This thesis investigated skeletal muscle strength, functional exercise capacity, health-related quality of life and daily physical activity pre- and early post-lung transplantation in a cohort of fifty participants. Significant functional limitations were observed pre-transplant, however levels of physical activity were higher on rehabilitation days as compared to non-rehabilitation days. Post-transplant, improvements in functional exercise capacity and physical activity lagged behind the early improvements in pulmonary function and health-related quality of life. Muscle strength was reduced at hospital discharge compared to pre-transplant levels, but improved to pre-transplant levels by three months post-transplant. In summary, significant functional limitation exists pre-transplant, and lung transplantation leads to significant improvement of functional outcomes; however functional recovery occurs at different time periods and to varying degrees, and does not reach levels of a healthy reference population by three months post-lung transplant.

Keywords: lung transplantation
exercise capacity
muscle strength
physical activity
health-related quality of life
Advisor: Brooks, Dina
The Evaluator Effect in Heuristic Evaluation: A Preliminary Study of End-users as Evaluators

Heuristic Evaluation (HE) is a popular usability inspection method. Yet little is known about the effect the evaluators have on the outcome of HE. One potentially important feature of evaluators is their end-user status, that is, whether or not they are end-users for whom the interface is designed. I completed a detailed review of the HE literature, combined sources, developed an explicit method for conducting an HE and trained HE novices from different work domains using it. Using these methods I conducted a preliminary randomized crossover study (n=6) of the effect of end-user status during the inspection and merging stages of HE. I estimate a larger study of approximately 148 end-users would be needed to test hypotheses regarding end-user status. I demonstrated a novel measure of the effect of end-user status for the merging stage of HE, which I called the measure of matching similarity (MMS).

Keywords: Heuristic Evaluation
Evaluator Effect
Usability
User Centred Design
Human-Computer Interaction
Software Design
End-user
Measure of Matching Similarity
Advisor: Etchells, Edward
Substrates and Substrate Interactions in Anaerobic Dechlorinating Cultures

Bioremediation of chlorinated contaminants in groundwater can be achieved by reductive dechlorination by anaerobic dechlorinating cultures. However, at sites impacted with multiple different chlorinated contaminants, reductive dechlorination is often inhibited by co-contaminants. The inhibitory effects of trichloroethene, cis-dichloroethene and vinyl chloride on chloroform dechlorination were studied using a Dehalobacter-containing chloroform dechlorinating mixed culture (ACT-3). The inhibitory effect of chloroform on chlorinated ethene dechlorination was studied in a Dehalococcoides-containing trichloroethene dechlorinating mixed culture (KB-1). Vinyl chloride was found to be the strongest inhibitor of chloroform in ACT-3. Chloroform exerted a complex and strong inhibitory effect on chlorinated ethene dechlorination in KB-1. The potential for microbial reductive defluorination was also examined in the enrichment cultures. Quantifying the substrates and substrate interactions in dechlorinating cultures is necessary to most efficiently use these cultures to remediate contaminated sites.

Keywords: Bioremediation
Environmental microbiology
Chlorinated solvents
Co-contaminant effects
Advisor: Edwards, Elizabeth A.
Emotional Arousal and Interference Resolution: A Test of Arousal-biased Competition in Younger and Older Adults

Arousal-biased competition (ABC; Mather & Sutherland, 2011) theory predicts that emotional arousal increases both the activation of relevant items and the suppression of irrelevant items in working memory. Study 1 tested ABC theory’s prediction in young and older adults. Suppression was measured with the Healey et al. (2010) paradigm and arousal was manipulated during interference resolution. Item accessibility was measured by comparing naming times of target and competitor words to baseline naming times. Young adults showed suppression of competitors while older adults did not. Arousal did not affect young adults’ naming times, but a mild suppression effect was seen in older adults whose arousal increased after the manipulation. A follow-up study showed that older and younger adults generally agreed on the arousing quality of the stimuli in Study 1. These studies partially support ABC theory and suggest that older adults may retain the ability to suppress irrelevant information when aroused.

Keywords: Arousal
Inhibition
Aging
Interference Resolution
Advisor: Hasher, Lynn
In it for the Long Run: An Ethnography of Psychological and Social Benefits of Distance Running

Recreational running is an activity increasing in popularity (Running USA, 2012). The current study sought to gain an ‘insiders’ perspective into the ‘lived experiences’ and social world of distance running so to explore the meaning, value and significance of the activity to the lives of ‘highly committed’ runners in Toronto (Canada). Ethnography of running club participants was used to inform the research. Findings suggest that commitment to distance running was effective for fulfilling a number of human ‘needs’, including for health, fitness, acceptance, belonging, self-esteem, autonomy, competence, relatedness and perhaps self-actualization as proposed by Maslow (1954) and Deci and Ryan (2000). Running was further conceptualized as a “serious leisure” (Stebbins, 1982) which helps explain the process of adaptively incorporating physical activity into one’s life and committing long-term. This research highlights some oft ignored psychological and social benefits of physical activity adherence which may contribute to improved overall health and well-being.

Keywords: ethnography
serious leisure
physical culture
human needs
self-actualization
self-determination
health
Advisor: Atkinson, Michael
Kerr, Gretchen