VictorJuiz/thesis huggingface dataset:
Mechanical Stability of Thin Films for Solid-state Batteries

The electrochemical performance of all-solid-state batteries (ASSBs) is limited to the mechanical instability of components. Volume expansion of components and Li dendrite formation are the main reasons for components fracture and reduced battery life. The mechanical behaviour of thin films fabricated by atomic and molecular layer deposition techniques (ALD and MLD, respectively) was studied using atomic force microscopy (AFM) based mechanical testing methods. Mechanical properties, including elastic modulus, failure forces, toughness, and fatigue, were evaluated for ALD and MLD thin films (

Advisor: Filleter, Tobin TF
Scaling CO2 Electrolysis

Anthropogenic carbon dioxide (CO2) emissions are the main driver of climate change, motivating the implementation of CO2 capture and utilization approaches. CO2 electrolysis offers a means to utilize CO2 and simultaneously store excess intermittent renewable energy. Despite tremendous promise, there are limited demonstrations of CO2 electrolysis beyond lab-scale. This thesis seeks to address barriers to scaling CO2 electrolysis systems and to their integration within larger systems. The first work couples CO2 electrolysis with alkaline electrolytes to better match the optimal anodic conditions wherein, with moderate pressurization, a record cathodic energy efficiency is obtained (Chapter 3). Focusing on the total electrolyzer electricity inputs, a low-resistance electrolyzer, capable of operating at industrially relevant pressures, demonstrates a record-high full cell energy efficiency for CO2 electrolysis (Chapter 4). To reduce the energy and capital costs of upstream CO2 purification, a simulated flue gas containing dilute CO2 and oxygen impurities is efficiently converted to multi-carbon products using moderate pressurization and a hydrophilic catalyst coating strategy (Chapter 5). Process simulations of the downstream purification processes are performed, demonstrating that CO2 removal from the electrolyzer tail gas, especially the anodic one, constitute the biggest energy penalty (Chapter 6). To integrate with large-scale process modelling, simultaneously integrating CO2 electrolyzers with upstream and downstream processes, a semi-empirical CO2 electrolyzer model is developed and validated against lab and pilot-scale experiments (Chapter 7). CO2 electrolysis is scaled by several orders of magnitude in the largest CO2 electrolysis pilot plant to date, in contention for the NRG COSIA Carbon XPRIZE (Chapter 8).

Keywords: CO2 reduction reaction
Electrocatalysis
Electrolysis
Advisor: Sinton, David
Cognitive Communication Impairment in Childhood Traumatic Brain Injury

Cognitive communication impairments are common sequelae of traumatic brain injury (TBI) but remain understudied in the paediatric academic literature. To synthesize the literature addressing cognitive communication impairments in childhood TBI and identify research priorities for the field, I completed a scoping review (Study 1); the three main findings of which guided my doctoral research. First, my scoping review identified younger age at injury as a significant contributor to negative cognitive communication outcomes with little known about language outcomes in early childhood TBI. To address this knowledge gap, I completed a retrospective chart review of the medical records at Holland Bloorview Kids Rehabilitation Hospital in Toronto, Ontario, Canada to characterize the communication performance of preschoolers within 3 months post-TBI (Study 2). Extracted language scores were broadly within average, with pre-injury language levels and dual-language learning likely contributors to performance. Second, my scoping review identified phonemic fluency as a sensitive measure for detecting cognitive communication impairment. However, no study included in my scoping review used semantic fluency, a measure that can be administered to younger children. To better understand the estimated the effects of injury by verbal fluency type (e.g. phonemic and semantic), severity, and over time I conducted a systematic review and meta-analysis (Study 3). Results revealed larger effects for phonemic fluency than semantic, severe TBI compared to mild and moderate TBI, and persisting effects of injury over time. Third, my scoping review identified that cognitive communication impairments persist after childhood TBI with little known about the effects of injury on the application of lexical knowledge. I conducted a systematic review and meta-analysis study to examine the estimated effects of pediatric TBI on verbal intelligence by severity and over time (Study 4). Results revealed larger effects in severe TBI compared to mild and moderate TBI and persisting effects of injury over time. Together, my dissertation identified language measures that may assist with earlier identification of cognitive communication impairments in paediatric TBI and individual factors that may assist with the personalization of paediatric TBI management.

Keywords: brain injury
child
neuropsychology
outcomes
speech-language pathology
Advisor: Beal, Deryk S.
Exploration of New Peripherally and Axially Halogenated Boron Subphthalocyanine Derivatives for Organic Electronics Applications

Organic semiconductors, or organic molecules with electron conducting properties, have been used in next generation electronic devices such as organic solar cells (OSCs). One of these materials is boron subphthalocyanine (BsubPc) which are molecules that embody many unique characteristics: exceptional light absorption capabilities, robust chemistry, highly tunable properties via chemical modification of the BsubPc periphery and axial positions, high ambient stability, and scalable and sustainable preparation processes. Our laboratory recently discovered that peripheral chlorination (ie. replacing all hydrogens with chlorines) of BsubPcs enhances light conversion efficiency of OSCs. Through the work of this thesis, it was found that peripheral fluorination also influences solubility, fluorescence quantum yield, nano-scale solid state arrangement, and electrochemical properties of BsubPcs, expanding the applicability of these BsubPcs beyond the OSC space. Chlorine and fluorine are both halogens with different atomic radii and electronegative features. Hence, this thesis has had the overarching goal of comparing BsubPc chlorination vs. fluorination and its effect on physical and electrochemical properties. A wide selection of BsubPc derivatives with various halogens in the periphery and carbon-based functional groups in the axial position were procured for this thesis to exemplify how influential peripheral and axial halogenation can be on the properties of BsubPcs, including spectroscopic, electronic, and nano-scale solid state arrangement. Incorporating carbon-rich frameworks onto the axial position of BsubPcs while also varying the BsubPc periphery with different halogens has further extended the library of new BsubPc derivatives and has built a foundation for further refinement of the BsubPc structure design rationale for specific energetic barriers and/or light absorption profiles of interest.

Keywords: chemistry
organic electronics
photovoltaics
subphthalocyanine
Advisor: Bender, Timothy T
The Impact of Professional Development on the Quality of Early Childhood Education Environments and Child Outcomes

Enrolment in Early Childhood Education and Care (ECEC) services is on the rise, with around one-third of children under age three enrolled in care. There is mounting evidence that high quality ECEC programs are an effective means for supporting children’s outcomes. Unfortunately, current research suggests that many children experience care that is mediocre. There is growing consensus that professional development (PD) is an important lever for improving educator practice. Effective PD can bolster early childhood educators (ECE’s) understanding of child development and can support their ability to create high quality instructional environments and interactions. However, the literature on PD for ECEs is highly heterogeneous, making it difficult to understand what works for whom. The motivation for Study One of this dissertation stemmed from the large heterogeneity in the PD literature in terms of the content areas that are targeted. To date, no published review integrated findings for all PD content areas reported in the literature. Thirteen independent meta-analyses (N=66 samples) were conducted, focusing on: School Readiness, Social Emotional Functioning through Interactions and Language/Literacy. Ten of the 13 meta-analyses were significant, with PD programs that focused on Interactions revealing the largest effects. The systematic review revealed that the inclusion of a coaching component is an important element of effective PD programs. The goal of Study Two was to test the effectiveness of the Responsive Interactions for Learning (RIFL) PD program; a theoretically driven PD program developed to target the quality of educator-child interactions, a key component of ECEC quality. A randomized control trial, was used to examine the effects of the RIFL PD program on interactions and overall classroom quality. The intervention group received a workshop, individual coaching and boosting of learned concepts through text reminders. The sample consisted of 86 educators (n= 46 experimental; n= 40 control) from 39 toddler classrooms in 27 community- and school-based centers. Evidence of improvement in interactions, measured both at the educator- and classroom- level was found. Professional development matters and it is through constant evaluation and improvement of PD programs that we can effect positive change on ECEC environments and child outcomes.

Keywords: Early Childhood Educators
Meta-Analysis
Professional Development
Randomized Control Trial
Responsive Interactions for Learning
Advisor: Perlman, Michal
Examining the Interplay of Emotion, Cognition, and Self-regulated Learning with Two Computer-mediated Learning Environments

This dissertation examines the real-time interactions of emotion and cognition across three stages of scientific problem-solving and identifies the intrapersonal and contextual factors contributing to students' optimal problem-solving pathways in two computer-mediated learning environments, referred to as Crystal Island and PeppeR. Analyses of multiple data sources (i.e., facial behaviour data, computer logfile, and survey data) not only showed that the pattern change of student affective states over time is the function of the interplay of emotion and task characteristics but also emphasized the importance of self-regulatory learning behaviour in mitigating a range of emotional intensity, regardless of the content and/or the cognitive demands of the learning tasks. These findings are highly valuable as they offer insights into student individual characteristics and learning behaviour in complex learning processes, which are crucial parameters for modelling students’ learning and engagement outcomes in technology-rich learning environments. Therefore, one implication of this study is to inform the design of computer-based learning environments that may benefit from individualized attention to students’ affective-and-cognitive states and optimize engagement in learning with computer-mediated learning environments. This research is premised on the notion that understanding the synchronic nature of emotional, cognitive, and self-regulatory elements of complex learning is critical to promote an optimized learning experience. Previous and emerging research, for example, has revealed the predictive value of emotion in learning and achievement, but research on emotion and learning continue to be under-researched. The study of emotion and learning with advanced learning technology is particularly sparse due to the dynamic, rapid-changing, and multifaceted nature of emotional processes and the evolving complexity of learners’ interaction with the learning technology. The dissertation aims to address this knowledge gap and examine the dynamic nature of emotion across multiple task contexts and attempts to identify the critical emotional, motivational, and behavioural determinants of student optimal learning trajectories.

Keywords: Emotion in learning
Facial emotion expression
Game-based learning
Optimal problem-solving pathways
Self-reflection
Self-regulated Learning
Advisor: Woodruff, Earl EW
Cell Contact and Tissue Architecture in the Xenopus laevis gastrula

Cell-cell contact and tissue architecture in the multilayered tissues of the Xenopus laevis gastrula is a complex and fascinating topic. These tissues must be flexible in order to allow for dynamic cell rearrangements while maintaining tissue integrity. Here, I describe the layout of these tissues by exploring the landscape of adhesive cell-cell contacts, describing the mechanics of interstitial channels between cells, and analyzing the effect of tissue-tissue interactions on tissue cohesion. I use transmission electron microscopy (TEM) to analyze the ultrastructure of these multilayered tissues. I find that modulation of adhesion is reflected structurally at cell-cell contacts which span a wide range of intercellular separation distances. Altogether, cell-cell adhesion in the Xenopus gastrula can be categorized into two general types: narrow contacts mediated by Syndecan-4 and C-cadherin along which cells are 0-50nm apart, and wider 50-1000nm contacts mediated by the glycocalyx. These tissues are also permeated by a network of channels that appear in TEM sections as interstitial gaps. I characterize this interstitial space in the ectoderm by examining the geometry and mechanics of gaps at three-cell junctions. From this, I generate a model of interstitial gap mechanics which suggests that gaps can be formed by the insertion of a fluid-like extracellular matrix material at three-cell junctions such that cell adhesion is locally disrupted and a small cortical tension difference between cell-cell contacts and the free cell surface at gaps of 0.003 mJ/m2 is generated. Lastly, to examine the effects of tissue-tissue interactions on tissue cohesion, I examined Eph/ephrin signaling at the ectoderm-mesoderm boundary. I show that the mesoderm is more sensitive to Eph/ephrin signaling than the ectoderm and that asymmetrical expression of a few Eph receptors and ephrin ligands establishes a mirror on the ectodermal side of the cleft which allows the mesoderm to be weakly self-adhesive and also weakly adhesive to the ectoderm. Integrating these concepts together, I propose that the flexible architecture of these multilayered tissues is maintained by a balance of adhesive contacts and non-adhesive gaps that can be regulated by tissue-tissue interactions.

Keywords: Cell adhesion
Cell contact
Glycocalyx
Pericellular matrix
Signaling
Syndecan
Advisor: Winklbauer, Rudolf RW
Germline Polymorphisms Contribute to Somatic Variability in Prostate Cancer

Cancer is the result of the successive accumulation of genomic mutations that confer biological capabilities, including sustained proliferation, resisting cell death and metastasis. Genomic mutations are caused by environmental, genetic and stochastic processes that promote tumour development and progression. These processes vary amongst individuals resulting in tumours with different somatic mutations catalogues, i.e. inter-tumoural heterogeneity. Inter-tumoural heterogeneity can influence diagnosis and treatment response. Understanding the origins of inter-tumoural heterogeneity facilitates personalize medicine.Germline genetics play an important role in cancer initiation and progression. Over 100 cancer predisposition genes and more than 403 predisposition loci have been identified to-date. However, it remains unclear how the germline genome influences the somatic mutational landscape of a tumour. To address this gap, I quantified the effect of the germline on the somatic genomic and epigenomic landscape in localized prostate cancer because prostate cancer is prevalent, heritable and presents with molecular and clinical heterogeneity. I identified 1,178 loci associated with DNA methylation changes in prostate tumour tissue but not non-malignant prostate epithelial tissue, termed tumour methylation quantitative trait loci (tumour meQTLs). Tumour meQTLs influence mRNA and protein abundances and chromatin structure and a subset of tumour meQTLs are predictive of aggressive disease, including an intronic loci within the oncogene AKT1. Next, I identified 62 loci associated with acquisition of somatic driver events, termed driver QTLs (dQTLs). dQTLs can predict risk of developing somatic driver events and may explain observed differences in somatic mutation frequencies across ancestry populations. Altogether, these data suggest the germline genome is a determinant of the somatic epigenomic and genomic landscape of localized prostate cancer, contributing to inter-tumoural heterogeneity. Finally, I illustrate how inter-tumoural heterogeneity can manifest clinically in prostate cancer diagnostic imaging. Specifically, I interrogated the molecular hallmarks of multiparametric magnetic resonance imaging (mpMRI) visibility and identified a confluence of aggressive pathological, molecular and microenvironmental hallmarks enriched in mpMRI visible compared to invisible tumours. These findings provide confidence in the ability of mpMRI to identify aggressive prostate cancer tumours and further motivate the importance of understanding inter-tumoural heterogeneity to improve personalized medicine.

Keywords: Epigenetics
Germline
mpMRI
Prostate cancer
Advisor: Boutros, Paul C
A Monolithic Masterless Fault-tolerant Hybrid Switched-capacitor Dickson Converter for 48-V Multi-phase Automotive Applications

Self-driving systems require a Fault-Tolerant (FT) power-management system to ensure continuous power delivery to safety processors, while the forthcoming 48-V bus necessitates high and wide power conversion ratios (e.g., 20-V-to-60-V input and 3.3-V output). To tackle these challenges, this work demonstrates a masterless FT multi-phase system with N+1 redundancy as the pre-regulator stage of a two-stage conversion system. Each phase is implemented based on a hybrid switched-capacitor 4-to-1 Dickson converter, which offers the best electrical performance and comparable cost and reliability among all common dc-dc topologies. This work proposes: 1) an independent quasi-fixed-frequency control scheme based on the valley-current on-time control, which enables masterless interleaving, current sharing, and self-balancing of the flying-capacitor voltages, 2) a fast and robust short-circuit and open-circuit fault detection of any power switches or flying capacitors, which only observes the switching-node voltage, and 3) an automotive-grade monolithic closed-loop single-phase FT 4-to-1 hybrid Dickson converter IC with masterless multi-phase operation capability, fabricated in a 0.13-um 90-V silicon-on-insulator bipolar-CMOS-DMOS process. The IC offers above 90 % efficiency at maximum 60-V-to-3.3-V conversion and 3-A load current while provides a peak efficiency of 95.3 % for 20-V-to-3.3-V conversion with 0.8-A load current and 320-kHz effective switching frequency. The performance of the design is evaluated and verified subject to various fault scenarios as well as input-voltage and load transients using discrete and IC prototypes.

Keywords: automotive
fault tolerant
hybrid switched capacitor
masterless
monolithic
multi-phase system
Advisor: Trescases, Olivier
The Role of Oxoguanine Glycosylase 1 (OGG1) as a DNA Damage Repair Enzyme and Epigenetic Modifier in Mitigating the Neurodevelopmental Disorders Initiated by Physiological and Ethanol-enhanced Levels of Reactive Oxygen Species

Mechanisms underlying neurodevelopmental disorders such as Autism Spectrum Disorders (ASD) and Fetal Alcohol Spectrum Disorders (FASD) may involve reactive oxygen species (ROS)-initiated DNA damage, measured as 8-oxoguanine (8-oxoG), and epigenetic modifications of histone proteins and DNA that regulate gene expression. 8-OxoG is repaired by oxoguanine glycosylase 1 (OGG1), and recently, 8-oxoG and/or OGG1 have been identified as epigenetic markers contributing to increased or decreased gene expression. This thesis explores the role of 8-oxoG and/or OGG1 in epigenetic modifications and neurodevelopmental abnormalities in Ogg1 knockout mice. The following results demonstrate that OGG1 alters both epigenetic marks and brain function: (A) Compared to wild-type controls, untreated Ogg1 knockout mice exhibit enhanced gene- and sex-dependent DNA damage (strand breaks) and decreased epigenetic methylation marks, increased cerebellar calbindin levels (reflecting Purkinje cell count), reduced hippocampal postsynaptic function and disorders of brain function reflected in behavioural tests for repetitive behaviour, anxiety and fear, object recognition and spatial memory, motor coordination and startle response. These results indicate that OGG1 plays an important role in normal brain development, possibly via both its DNA repair activity and its role as an epigenetic modifier, suggesting that OGG1 deficiencies potentially contribute to developmental disorders like autism. (B) In utero exposure to a single low dose of ethanol (EtOH) can alter epigenetic marks and gene expression in fetal brains, along with postnatal behaviour, in an OGG1-dependent manner. Specifically, OGG1 may play a role in estrogen receptor-mediated gene regulation that is further altered by in utero EtOH exposure, possibly contributing to sex-dependent behavioural differences observed in OGG1-deficient progeny. (C) Furthermore, postnatal administration of the histone deacetylase inhibitor trichostatin A (TSA) to progeny exposed in utero to EtOH variably reversed or enhanced the behavioural disorders caused by EtOH, which were OGG1- and sex-dependent, suggesting that both EtOH and TSA may alter behaviour via an epigenetic mechanism involving OGG1. Overall, these results suggest that OGG1 plays an important role in fetal brain development, and protects against physiological and EtOH-enhanced ROS levels. OGG1 deficiencies may constitute a risk factor for neurodevelopmental disorders such as ASD and FASD.

Keywords: 8-oxoguanine (8-oxoG)
DNA damage and repair
Epigenetics
Oxidative stress
Oxoguanine glycosylase 1 (OGG1)
Trichostatin A (TSA)
Advisor: Wells, Peter G.