VictorJuiz/thesis huggingface dataset:
Towards Understanding Heterogenous Interactions in Photocatalysis
Keywords: Heterogeneous
Photocatalysis
Pollution Remediation
TiO2

Photocatalytic materials are an interesting subset of nanomaterials capable of converting light into chemical energy. The basis of any heterogeneous photocatalytic reaction involves a redox driven transformation of a small molecule by a semiconducting material, often colloidal nanoparticles. Several questions remained surrounding the physical interactions at play, notably in interactions between small molecules and the colloidal nanoparticle. Herein, four studies aimed at improving our understanding of the photocatalytic process are provided. The first study investigates how conventional 1D NMR can be utilized to follow the progress of photocatalytic reactions. NMR provides a number of advantages over traditional techniques and allows for more environmentally relevant reactions to be studied. Next, the first application of comprehensive multiphase (CMP) NMR to catalytic systems, revealing that molecules transiently interacting with the surface of the nanomaterial appear to be those preferentially targeted by photocatalysis. CMP NMR provides a more holistic approach to studying photocatalysis overall owing to its ability to monitor reactions without sample preparation. The next study discusses a series of TiO2- Nitrogen Doped Graphene Quantum Dot (NGQD) nanocomposites as potential solar photocatalysts. These species show an improved ability to harvest visible light and show increased photocatalytic performance. This improvement appears to multifaceted being due to both a Z-Scheme heterojunction present at the interface of the composite and increased organic retention provided by the NGQDs. The Z-Scheme architecture allows for the highly oxidizing valence band holes of TiO2 to be retained during charge transfer while the organic retention of the NGQDs allows for higher turnover of photocatalytically generated intermediates and a higher degree of interaction between the small molecules and TiO2. Finally, a framework to study photocatalysis of mixtures was used to monitor the degradation of a 2 dye system ii using both TiO2 and g-C3N4 catalysts. Within model system containing Methyl Orange and Methylene Blue dyes, a catalytic enhancement in Methyl Orange’s degradation in the presence of g-C3N4 was found to be caused by increased surface adsorption and secondary homogeneous photosensitization processes. Contrarily, in the presence of TiO2, Methyl Orange’s catalytic degradation was hindered due to competition for photogenerated radical species.
Translating Ismaili Muslim Experience in Canada: Integrative Choral Pathways of Belonging
Keywords: Choral music
Intercultural translation
Ismaili Muslim
Muslim cultures
Soundscape
Zikr

This study explores possibilities for blending choral forms of singing with traditional Ismaili Muslim devotional recitations. In particular, the focus is on finding new musical translations as a means of interpreting tradition and negotiating belonging in Canada. In music education scholarship, Muslim musical traditions can often be portrayed in ways that delimit the communities represented. In doing so, Islam may be inadvertently positioned as a problem to be addressed. Furthermore, there is a paucity of scholarship in music education that illustrates the importance of sound and music in diverse Muslim cultures. This study aims to further the conversation. I propose an “enlightened encounters” theoretical framework that draws together post-colonial, indigenous, educational social justice, and Ismaili literature. Autoethnography and narrative research methods foreground the transformative impacts of integrative vocal practices on retranslating Muslim experience in new contexts. Key findings include: 1) Blended sound and music can play a significant role to feel faith and embody cultural knowledge; 2) Integrative vocal practices can provide the possibility of avenues for Ismaili youth to navigate delicate relationships of belonging within their own traditions, as well as in the larger cultural context; 3) Engaging in participatory communal activities can provide youth with safe spaces for receiving, translating and interpreting knowledge; 4) Music and sound can have a powerful impact on reconnecting spirituality with life.
Pigment Cells Model Lineage Regulation and Cell Clearance in the Planarian Schmidtea mediterranea
Keywords: Cell death
Efferocytosis
Phagocyte
Planarian
Regeneration
Stem cells

Billions of cells are replaced in adult humans every day, yet many of the mechanisms of cell turnover are still poorly understood. In particular, the clearance of dead cells by engulfment, a processed termed “efferocytosis”, remains mysterious. In this thesis, I investigate cell turnover using the freshwater planarian Schmidtea mediterranea, a model organism that undergoes constant cell turnover as an adult and is capable of regenerating all of its organs and tissues. Using light-induced ablation of pigment cells, I first characterize the pigment lineage as a model for cell clearance. Next, I investigate the molecular mechanisms of efferocytosis in planarians, and find that the highly conserved engulfment receptor CED-1/Draper/MEGF10 is not conserved in planarians. Instead, I demonstrate that a related gene, megf6, and the extracellular matrix component hemicentin both function to restrict the stem cell compartment by maintaining the integrity of the basement membrane. Finally, by tracking planarian pigment cells following light exposure, I demonstrate that apoptotic cell corpses are transported to the gut, where they are engulfed by gut phagocytes and excreted from the animal. The planarian ortholog of the conserved engulfment gene CED-12/ELMO is required for efferocytosis of pigment cells by gut phagocytes. Together, these results provide the first insight into the mechanisms of cell clearance in planarians.
Mental Health, Coping, Resilience, and Community in Plurisexual Emerging Adults
Keywords: plurisexual
well-being

Despite cultural shifts in the acceptance of sexual minority individuals, plurisexual people continue to face mental health disparities in comparison to their monosexual counterparts. This study investigated how stressors (e.g., identity uncertainty, internalized homonegativity, experiences of microaggression), and resources (e.g., resilience, social support, connectedness to LGBTQIA2S+ communities) relate to psychological well-being and distress in plurisexual emerging adults. It also explored how this population describes and labels their sexual identities. Participants completed an online survey assessing the above-listed variables, as well as measures related to sexual identity, fluidity, and coping. All 774 participants were between the ages of 18 and 29, experienced attraction to more than one gender, and were living in Canada or the USA. Results indicated high levels of anxiety and depression in the sample. Minority stress was predictive of poorer mental health outcomes, while social support and resilience served as protective factors. Implications for counselling interventions are discussed, as well as the importance of education and training for clinicians to address the specific needs of this population.
Power-Efficient Voltage-Mode RF Front-End Using Quantized Analog Signal Processing
Keywords: Digital calibration
Power efficient
Power scalable
Quantized Analog
RFIC
SAW-less

In favour of saving precious real-estate and reducing overall cost for modern RF front-ends, SAW (Surface Acoustic Wave)-less RF receivers have become a popular topic recently. Unfortunately, removal of SAW filters requires the receiver to handle large blockers (e.g., above 0 dBm) without degrading the noise floor and in turn increases the overall power consumption of both the signal and local oscillator (LO) paths. My contributions to the state-of-the-art SAW-less receivers for my PhD addresses the abovementioned issues and can be summarized in the following major points: 1) for the first time, voltage-mode approach was made compliant to modern SAW-less receiver specs by the use of Quantized Analog (QA) signal processing, 2) for the first time, power scalability feature for the LO is introduced where LO power is scaled based on the operative scenario, leading to a significant power reduction compared to state-of-the-art (e.g., down to 1.6 mW for the LO), 3) an automated calibration platform was developed for the QA receiver where it significantly increased the linearity performance (e.g., up to 33 dB improvement for both third-order and second-order intermodulation products compared to non-calibrated), and 4) a novel multi-stage QA low-noise amplifier (LNA) was investigated with the introduction of tree architecture which dramatically reduces the power consumption and input capacitance when large input swing for the LNA is required.The first chapter reviews the state-of-the-art SAW-less receivers which identifies the core issue of excessive power consumption in these modern receivers and to appreciate the outlined solutions presented in this thesis. Chapter 2 presents the employed design strategies in the proposed receiver to address the excessive power. In chapter 3, the proposed SAW-less RF receiver design is presented as well as the manufactured test chip with its measurement results, with the results verifying points 1) and 2) above. Chapter 4 provides the automation calibration platform developed to increase overall linearity performance of the first QA test chip described in point 3) above. In chapter 5, the novel tree QA architecture is presented along with simulation results verifying point 4) above. The last chapter provides concluding remarks of the entire thesis.
Modelling Additively Manufactured Material for Applications in Topology Optimization
Keywords: Additive
Manufacturing
Optimization
Topology

Topology optimization and additive manufacturing are two emerging technologies which complement one another. Topology optimization can produce highly efficient, non-intuitive designs, which are difficult to manufacture, and additive manufacturing can be used to make highly intricate designs. However, despite this apparent mutually beneficial relationship, they are not used in conjunction in industry. One of the reasons for this is the inconsistency in the printed material and consequentially there is a lack of an accurate material model. This thesis focuses on addressing this issue by designing finite element models that describe the unique features of additive manufacturing; developing a material testing technique to quantify stochastic material properties associated with layer fusion; and demonstrating the usefulness of the finite element models and material testing technique through topology optimization. Two finite element models are described in this thesis, the first provides a novel description of the material density based on filament angle and the second allows separate material descriptions for the fusion and bulk material. The first of these finite element models allows more efficient optimization algorithms to be used in dual printing angle and topology optimization algorithms, including algorithms which contain stress constraints. The second of these two finite element models allow sources of uncertainty associated with the fusion between printed layers to be separated. Furthermore, the developed experimental technique can capture this local information. The experimental technique uses digital image correlation to measure local strain, which is used to calculate the mean, standard deviation and correlation length of the Young’s modulus for both the fusion and bulk regions. It is then demonstrated how these random field properties can be incorporated into topology optimization algorithms using both intrusive and non-intrusive methods to quantify the uncertainty.
Formal Teacher Leadership and the Education Management Hierarchy
Keywords: Education Management
Hierarchy
Invisible Leadership
Micropolitics
Position of Responsibility
Teacher Leadership

Teacher Leadership has become a significant area of interest for building capacity within schools. This qualitative study centres on the constraints imposed on teacher leaders in their relationships with teachers and administration. The impact hierarchical relationships have on the effectiveness of the teacher leadership role is of particular interest. Micro-political analysis of teacher relationships in schools research on collegial teacher interactions are fundamental to this study. A lack of formal policy recognition may contribute to the way teacher leaders engage in their roles, their role ambiguity, and their lack of authority. The results show that teacher leaders navigate their roles by engaging in “invisible leadership” or “leading from the center” as teachers, mentors, guides, confidantes, and leaders in their “teachership” within their school communities. Many of the teacher leaders use their emotional intelligence and micro-political strategies to navigate collegial relations in their roles with other teachers and the education management hierarchy. The data demonstrated that some teacher leaders are identified and mentored very early in their teaching careers, while others bring skills from other industries and university training to support them in their work. The teacher leadership role is complex and has become a topic of interest in sustaining reform efforts and catalyzing change. This research provides further insights into the micro-political and collegial relations of teacher leaders within the education management hierarchy and the supports leading to their effectiveness.
Influence of Obstructive Sleep Apnea (OSA) on Rostral Fluid Shift, and the Pathophysiology on Asthma
Keywords: asthma
obstructive sleep apnea
rostral fluid shift
small airway narrowing
thoracic fluid accumulation

The presence of obstructive sleep apnea (OSA) in persons with asthma confers a heightened risk of overnight exacerbation of asthma, declined lung function, increased airway hyperresponsiveness, and greater need for asthma medications. Previous studies showed that overnight fluid shift from the legs into the neck and peripharyngeal tissues increases upper airway resistance and severity of OSA. Recent findings also indicated that in asthma, fluid shift into the thorax induced by lower body positive pressure (LBPP) while supine provokes an increase in small airway resistance. However, whether fluid redistribution links OSA with asthma remains unknown. This thesis aimed to investigate the role of fluid accumulation in the thorax in the pathophysiological link between OSA and asthma. The central hypothesis is that one mechanism by which OSA can predispose to small airway narrowing in asthma is by aggravating fluid accumulation in the thorax during sleep. We found that simulated obstructive apneas in awake participants increased thoracic fluid volume (TFV) by approximately 50 ml in both healthy and asthma groups. However, small airway narrowed only in the asthma group, indicating that increases in TFV resulting from negative intrathoracic pressure swings during simulated apneas, increase small airway narrowing in patients with asthma, but not in healthy controls (Chapter 3). We expanded this work into the overnight and clinical setting, and found that patients with asthma and co-existing OSA had a larger increase in TFV and greater small airway narrowing than asthma patients without OSA (Chapter 4). Moreover, we investigated whether asthma treatment with bronchodilators can prevent the airway narrowing that is attributable to rostral fluid shift. It was found that small airway narrowing would increase after application of LBPP, both with and without bronchodilator (Chapter 5). Finally, we developed a model of the respiratory system, to estimate elastance of the airway tissues and total respiratory system in patients with asthma in response to increase in TFV. Our modelling results showed that increases in TFV was associated with an increase in airway tissue elastance (Chapter 6). Taken together, these studies demonstrate that fluid accumulation in the thorax narrows the small airway in patients with asthma, and contributes to the pathophysiological link between OSA and asthma.
Ephrin-B2 and EphB4 Signaling in the Development of Fibrosis
Keywords: EphB4
Ephrin-B2
Fibroblast
Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a pathology featured in many diseases frequently classified as interstitial lung diseases. Deregulated extracellular matrix (ECM) remodeling disrupts lung architecture, causing decreased lung function and patient mortality. Current therapies are limited to slowing rather than halting disease progression. We previously identified fibroblast-derived ephrin-B2 as a key mediator of PF. This work seeks to further evaluate the role of ephrin-B2 and its potential receptor ephB4 in PF development. Ephrin-B2 is highly expressed in endothelial cells within lung tissue, and this work seeks to address whether endothelial expression of ephrin-B2 contributes to PF. We have previously identified ephB4 as a likely target for ephrin-B2 signaling in PF. I sought to evaluate whether ephB4 ablation on fibroblasts was sufficient in protecting against the development of PF using a conditional type I collagen-driven Ephb4 KO mouse line that I generated. Ephb4 CKO substantially protects against bleomycin-induced PF in mice. RNA sequencing was performed on lung fibroblasts isolated from ephB4 KO mice and control mice to assess its signaling mechanism. 11 ECM and 7 protein transport genes were downregulated with the KO of fibroblast ephB4; this is the first study to link ephB4 signaling to fibrotic extracellular matrix remodeling and secretion. To evaluate whether ephB4 pharmacological inhibition could also impact ECM and protein transport NanoString was performed on mouse and human fibroblasts treated with profibrotic cytokine TGF-β1 and ephB4 inhibitor NVP-BHG712. ECM and protein transport genes were downregulated in mouse and human fibroblasts. Human fibroblasts treated with NVP-BHG712 downregulate the expression of classic pro-fibrotic markers. Mice administered with ephB4 inhibitor 5 days post-bleomycin challenge developed markedly less PF compared to controls. RNA sequencing of human IPF fibroblasts indicate that a key potential downstream target of ephB4 signaling is ELN. ELN was shown through human protein-protein interactions to share TGF-β1 as an interaction partner with ephB4. Mice therapeutically treated with ephb4 inhibitor downregulate ELN in lung tissue after initiation of fibrosis. Ultimately, ephB4 signaling shows excellent potential in both understanding the mechanisms of fibrosis pathology, and in future translation towards addressing human disease, potentially by modulating key ECM proteins like ELN.
Gut Hormone Regulation of Hepatic and Intestinal Lipoprotein Production
Keywords: Chylomicron
Dyslipidemia
GLP-1
Insulin Resistance
Vagus

Dyslipidemia is a key component of insulin resistance, which results in the overproduction of hepatic and intestinal apolipoprotein (apo)B-containing lipoprotein particles. These particles are catabolized down into highly proatherogenic remnants. Several gut-derived peptides have been identified as regulators of energy metabolism; one such peptide is the incretin hormone glucagon-like peptide (GLP)-1. Our laboratory has previously demonstrated that GLP-1 can signal both centrally and peripherally to reduce postprandial and fasting lipoprotein secretion. Here, I examine a novel vagal neuroendocrine signalling pathway by which native GLP-1 may exert its anti-lipemic effects. Furthermore, I demonstrate a novel role for other gut-derived peptides in regulating intestinal lipoprotein production. Portal vein injections of GLP-1(7-36) into Syrian golden hamsters revealed a site-specific anti-lipemic role for native GLP-1. This effect was lost after GLP-1R antagonism, and in a GLP-1R KO hamster model. The suppressive effects of portal GLP-1 on intestinal lipoprotein excursion were also lost after chemical, pharmacological, surgical, or selective denervation of the vagus nerve – together identifying the vagus nerve as a key component of GLP-1's endogenous signalling pathway. Moreover, we demonstrate a role for nodose ganglia GLP-1R-containing neurons in propagating anti-lipemic viscerosensory signals. These data are complimented by the finding of portal and nodose ganglia GLP-1 resistance following diet-induced insulin resistance, suggesting loss of this vagal GLP-1 signalling pathway may occur at the advent of diabetic dyslipidemia. The role of other gut- derived anorexigenic hormones were also investigated, and we identified that Peptide YY, oxytocin, and cholecystokinin (CCK) also exert a suppressive effect on postprandial lipoprotein metabolism. Importantly, we also delineate the effect of CCK receptor signalling from bile acid release on postprandial lipemia. This in combination with data showing CCKs effects are lost in GLP-1R KO hamsters suggests that CCK may exert its effects though bile acid-mediated increases in GLP-1 secretion. Overall, the data presented here supports a key role for GLP-1 receptors on the portal vein afferent neurons in modulating intestinal fat absorption and lipoprotein production and identifies other gut-derived peptides as novel regulators of postprandial lipemia. Insights from these data may support identification of potential drug targets for treatment of diabetic dyslipidemia.
Development of Nontargeted Screening Algorithms for Indoor Contaminants
Keywords: Indoor Chemistry
Mass Spectrometry
Wastewater

Humans spend most of their lives indoors, but there are thousands of chemical contaminants in indoor environments and the majority of these remain undetected. The focus of this thesis was to develop methods for nontargeted screening and prioritization of previously unreported indoor chemical contaminants using high-resolution mass spectrometry. To achieve this, a one – stop suspect screening algorithm was developed incorporating retention time prediction, isotopic peak calculation and in silico MS2 prediction. The algorithm was benchmarked for halogenated compounds and was further applied to screen for previously unrecognized indoor contaminants. Among 39 chlorinated compounds detected, 18 previously unrecognized azo dyes were detected as the biggest class of indoor chlorinated compounds (Chapter 2). To further characterize the indoor sources of these chlorinated compounds, various consumer products were collected from Toronto homes and screened for toxic halogenated contaminants with an emphasis on chlorinated paraffins. Chlorinated paraffin compounds were detected in 84 of 96 products analyzed, including electronic devices and plastic children’s toys, despite these compounds being prohibited for manufacture or import in Canada as of 2013 (Chapter 3). In addition to direct emission sources, the indirect sources of indoor contaminants formed through indoor reactions were investigated. To achieve this, an R package (‘indoortransformer’) was developed to predict indoor transformation products of organophosphorus compounds (OPCs). By further expanding the R package to incorporate in silico MS2 fragmentation prediction, 40 OPCs were detected in 23 house dust samples among which 24 OPCs were predicted to be formed through indoor reactions (Chapter 4). To systematically investigate the emission of contaminants from indoors, wastewater samples were collected over a 1.5 year period during the COVID-19 pandemic and screened against the ToxCast and Tox21 databases. Among 1037 ToxCast compounds, 43 were detected with high frequency plus 8 additional dyes and OPCs. Several plasticizers and disinfectants also showed an increase in concentration during periods of public lockdown (Chapter 5). This thesis provides a systematic exploration of the occurrence, source, reactions and temporal trends of many indoor contaminants. Future studies are warranted to expand the nontargeted screening methods developed in the current study to additional indoor compound classes.