VictorJuiz/thesis huggingface dataset:
Design of Optically and Electronically Active Organic Chalcogen Materials

In this thesis, I describe efforts to design chalcogen-containing organic materials for optical and electronic applications.Chapter 1 introduces how the substitution of heavy chalcogens in organic materials affects various properties. Sulfur-containing compounds, particularly derivatives of thiophene, are well studied for organic electronics applications. Incorporating selenium or tellurium in place of sulfur imparts different physical and chemical properties due to the fundamental differences of these atoms relative to their lighter analogues. These varied changes have a profound influence on the possible functions of these molecules, which ultimately leads to new photoactive and optoelectronic applications. Chapter 2 describes exploratory attempts to modify the photophysical rates of thermally activated delayed fluorescence (TADF) emitters through single-atom substitution of selenium for sulfur. It includes my efforts toward synthesizing a variety of compounds expected to have enhanced photophysical properties, as well as photophysical data directly comparing a selenium-containing TADF emitter to its sulfur analogue. Chapter 3 introduces a new computational assignment based on TADF emitters for upper-year undergraduate and graduate students in materials chemistry. The module requires students to examine the benefits and caveats in using computational chemistry, specifically in the context of predicting the optoelectronic properties of organic small molecules and the subsequent performance of these molecules in functional devices. It has been implemented in the CHM 446 curriculum for two years. Chapter 4 describes efforts to utilize the unique chemistry of organotellurium compounds in multi-component systems. It begins with the synthesis of an asymmetric tellurophene which is thiol-modified to allow conjugation to a gold surface. I then describe my attempts at utilizing the ligand, first as a conjugate to gold nanoparticles, and second as the active component toward halogen sensors using surface-confined electrochemistry. Chapter 5 presents a summary of the other chapters, discusses approaches toward strengthening the educational module, and proposes specific structural modifications to improve the performance of the discussed materials.

Advisor: Seferos, Dwight S.
Nonlinear Wave Propagation in High Frequency Ultrasound Imaging

The existing safety standards for diagnostic ultrasound devices were developed for low frequency systems (1 to 10 MHz) under the assumption that nonlinear effects are negligible. However, the standards are now being used for relatively high frequency systems (up to 70 MHz); nonlinear effects are increasingly evident as the working frequency f0 is increased. The main goal of this project is to determine if the coverage of nonlinear effects in safety standards in terms of thermal and non-thermal effects is adequate for equipment with f0>10 MHz. To achieve this goal, a practical variation to the finite amplitude method for determination of B/A is proposed, and the values of B/A are measured from 2.25 to 20 MHz for water. It is shown that there is no statistically significant variation with f0 for the value of B/A. The appropriate value of B/A in tissue is used as input to a nonlinear pulse propagation model in the time-domain. The total heat deposition pattern due to ultrasound absorption is then calculated and used as input to a bio-heat model. The maximum peak-rarefactional pressure is also extracted from the nonlinear pulse propagation results and used to calculate the Mechanical Index MI. We propose a slight modification to MI to solve the inconsistencies associated with the coverage of nonlinear effects in MI. A modification is also required in the existing upper limit for the hydrophone calibration bandwidth to ensure that the fundamental component is fully captured at high frequencies.The thermal results show that strong higher order harmonics can significantly increase the local heat deposition rate. However, at the same time, they lead to an increase in the rate of axial and radial heat conduction, thereby reducing the net impact on the steady-state temperature rise. Also, the effect of higher order harmonics can be significant on the temperature rise at the focal point, while the maximum temperature rise always occurs close to the skin surface. We conclude that current safety standards are adequate in assessing thermal effects in B-mode imaging at high frequencies despite ignoring the extra heat deposited by higher order harmonics.

Keywords: B/A
high frequency
nonlinear wave propagation
safety standards
thermal effects
ultrasound imaging
Advisor: Sinclair, Anthony AS
Early Identification of Dysphagia Post Pediatric Ischemic Stroke

Pediatric stroke has received increasing attention over the last few decades. Dysphagia is commonly reported following acute stroke in adults, leading to negative health complications such as pneumonia and mortality; however, dysphagia is not a well understood outcome post-stroke in pediatrics. This dissertation sought to explore early identification of dysphagia, with a focus on pediatric stroke, and was comprised of four studies: 1) a meta-analysis of high-level evidence on the benefit of dysphagia screening in adult stroke, 2) a systematic review of available literature on pediatric stroke and dysphagia; 3) a retrospective chart review to identify frequencies, co-occurrence and associations of dysphagia, motor speech and language impairment in pediatric stroke; and 4) a prospective survey of dysphagia experts to determine opinion of relevance and feasibility of assessment items to move forward in the development of a dysphagia screening tool. This dissertation confirmed the benefit of dysphagia screening in the adult stroke population. Further, this work identified dysphagia as a relatively common impairment post-stroke in the acute phase in pediatrics, similar to adults, and especially highlighted the need for standardized assessment protocols in the younger population. Lastly, this dissertation identified a list of assessment items to move forward in the development of a pediatric dysphagia screening tool post-stroke. Future work is indicated and discussed to further advance this under-researched area of dysphagia and pediatric stroke.

Advisor: Martino, Rosemary
Identité professionnelle et rôle des enseignantes et des enseignants dans les écoles de langue française en Ontario

In addition to transmitting academic knowledge and socializing students, teachers working in a linguistic minority context must be a linguistic and cultural model for these young people. Their task is complex and comes with many challenges not faced by their counterparts in English-language schools. This research aims to understand how teachers in French-language schools in Ontario perceive themselves personally and professionally. Based on the life stories of seven teachers, we are interested in exploring how their rapport to identity will have an influence on how they perceive their role in fulfilling the mandate of French-language schools, particularly with regard to the transmission of French language and culture, given the close link between personal and professional identity. Analysis of the results reveals that teachers understand their role as agents of linguistic reproduction, but have a poor understanding of their role in the transmission of French culture. Despite the many policies and initiatives implemented by the government to support their work and help them fulfill the mandate of French-language schools, teachers tend instead to interpret their role according to their representations of their own linguistic and cultural identity, as well as their representations of the culture of expression, interpreted according to a traditional and folkloric vision of this notion.

Keywords: French Canadian Culture
French Language Education
Minority Language Education
Ontario Education
Professional Identity
Teacher Identity
Advisor: Gérin-Lajoie, Diane
From Safe to Safeguarding: Conceptualizing and Advancing Safe Sport

The following dissertation sought to understand how sport stakeholders conceptualize and experience safe sport and to elicit their recommendations to advance safe sport, a movement that has emerged in response to cases of athlete maltreatment. To-date, the related literature indicates there is no universal definition of safe sport and thus, prevention and intervention initiatives differ; further, these initiatives are not necessarily empirically or theoretically driven. In Study 1, a constructivist grounded theory was employed, and semi-structured interviews were conducted with forty-three stakeholders in sport to elicit views of the meaning of the term safe sport. The findings revealed commonalities among the participants’ interpretations, specifically pertaining to the prevention of and intervention in incidences of physical, psychological, and sexual harm. Additionally, some participants’ interpretations expanded beyond the prevention of harm to include the optimisation of the sport experience, characterized by the promotion of positive values and human rights. In Study 2, an interpretive phenomenological analysis was used to explore equity-deserving athletes’ understanding and lived experiences of safe sport. Semi-structured interviews were conducted with seven athletes of diverse intersectional identities. The findings suggest that athletes from equity-deserving groups experience verbal and non-verbal forms of discrimination in sport and questioned whether safe sport was an attainable outcome for them. Moreover, athletes with visible, under-represented characteristics (e.g., Black, physical disability) perceived themselves as more vulnerable to unsafe sport experiences compared to athletes who could hide elements of their identity (e.g., gay athletes). Finally, Study 3 was a constructivist grounded theory that utilized semi-structured interviews to explore thirteen sport administrators’ perspectives of advancing safe sport. The participants recommended that sport organisations establish a universal framework of safe sport, design and implement education, implement and enforce policies, establish independent monitoring and complaint mechanisms, and conduct research to ensure advancement strategies are current and applicable. The current dissertation contributes to the growing body of safe sport literature by recommending that conceptualizations and advancement strategies of safe sport, which tend to be focused on the prevention of harm, extend to the promotion of human rights in sport through safeguarding.

Keywords: human rights
safe sport
safeguarding sport
Advisor: Kerr, Gretchen A
Acoustic Assessment of Sleep Apnea and Pharyngeal Airway

Sleep apnea is a chronic respiratory disorder that is characterized by recurrent reductions in breathing during sleep. The gold standard diagnosis of sleep apnea is an overnight sleep study with polysomnography (PSG), which is expensive and time-consuming. Furthermore, questionnaires are used for screening of sleep apnea during wakefulness, but they are highly subjective and do not provide the assessment of pharyngeal airway anatomy. This thesis presents acoustic technologies to diagnose sleep apnea during sleep and to assess the pharyngeal airway dimension during wakefulness. To diagnose sleep apnea during sleep, we recruited 69 individuals who underwent full-night PSG in the sleep laboratory. Simultaneously with PSG, we recorded the tracheal breathing sounds and respiratory-related movements with a microphone and an accelerometer, respectively. We developed a novel machine-learning algorithm utilizing random forest and logistic regression; and achieved 90% accuracy in detecting sleep apnea. We also identified each respiratory event with over 80% accuracy in patients with severe sleep apnea. Furthermore, we utilized deep convolutional networks to use breathing sounds and distinguish the two major sleep apnea types, obstructive and central events, with 84% accuracy. These algorithms can be used in a wearable device for monitoring sleep apnea. To assess the pharyngeal airway during wakefulness, we investigated vowel articulation and acoustic features of vowel sounds. To measure the pharyngeal airway effectively during vowel articulation, we used ultrasonography. We have shown that ultrasonography can be effectively used to measure the dimensions of the pharyngeal airway and the dimensions are different between individuals with and without sleep apnea. Furthermore, we have shown that patients with sleep apnea have had less variation in the pharyngeal airway dimension, which can be interpreted as less tongue movement than control groups while articulating vowels. Moreover, we have shown that the vowel sound features can estimate the pharyngeal airway dimension with high accuracy. These algorithms can be used for developing a vowel-based assessment of sleep apnea. Overall, the results of these studies showed the promise of breathing and vowel sounds to assess the pharyngeal airway and monitor sleep apnea.

Keywords: Machine Learning
Obesity
Pharyngeal Airway
Sleep Apnea
Ultrasonography
Vowel Sounds
Advisor: Yadollahi, Azadeh Prof.
Identifying the Anatomical Layout and Molecular Properties of the GABAA Motivational Switch in the Ventral Tegmental Area

The motivation to seek natural reinforcers and drugs can transform over time from a form of pleasure-seeking to a form of relief-seeking. This shift from a positive reinforcement-based motivation to a negative reinforcement-based motivation is a hallmark of several substance use and eating disorders. Our group has demonstrated a double dissociation wherein the former motivational state is mediated by the tegmental pedunculopontine nucleus (TPP), while the latter is mediated by mesolimbic dopamine (DA). In this thesis, I demonstrate the functional role that brain-derived neurotrophic factor (BDNF) and connexin-36 (Cx36)-containing gap junctions play in this switching mechanism. Specifically, I show that intra-VTA infusions of BDNF produce a drug-dependent and withdrawn phenotype in otherwise drug-naïve animals and that lentiviral knockdown of the BDNF receptor, TrkB, prevents the manifestation of opiate dependence and withdrawal. I also show that Cx36 is necessary and sufficient for opiate dependence susceptibility, as evidenced by my finding that intra-VTA infusions of the pharmacological blocker, mefloquine, result in a reversion of opiate-dependent and withdrawn (ODW) rats to a drug-naïve state, that conditional knockout mice lacking Cx36 in GAD65+ cells are perpetually drug-naïve, and that viral-mediated rescue of Cx36 in VTA GABA neurons is sufficient to restore susceptibility of those mice to opiate dependence. These studies further characterize the GABAA switch that is causally linked to maladaptive drug-seeking.

Keywords: Drug dependence
Gap Junctions
Motivation
Opiates
Reward
Ventral Tegmental Area
Advisor: van der Kooy, Derek
The Effect of Pre-eclampsia and HIV on the Expression and Regulation of Drug Transporters in Placenta

Disease-mediated changes in the expression and activity of placental ABC and SLC drug transporters have been extensively studied in animal models resulting in altered transplacental passage of their substrates. While these transporters are likely also dysregulated in human placental tissues, translational studies are lacking and thus little is known about expression and regulation of these clinically important drug transporters in patients with Pre-eclampsia (PE) and Human Immunodeficiency Virus (HIV). Moreover, statistics indicate that prescription drug use in pregnancy is on the rise and is likely higher in these two conditions. In two separate studies, we used placental tissues obtained at birth from women with PE and HIV, to investigate the effect of these two diseases on the expression of highly expressed and clinically relevant drug transporters. We further used in vitro cultured placental cells and cultured placental villous explants to further understand the effects of angiogenic factors in the context of PE and ARVs in the context of HIV on the expression of several drug transporters. Our studies demonstrated that both PE and HIV resulted in widespread dysregulation of several placental uptake and efflux transporters from women with clinically diagnosed disease. Additionally, within our PE group, placental angiogenic factor sFlt-1 was significantly induced while VEGF and PLGF were significantly downregulated in PE placentas compared to non-PE controls. These were further investigated in vitro where they were found to play a role in the regulation of BCRP and OATP2B1 expression. Within our HIV group, many women were on prescribed antiretroviral regimens, some of which were found to significantly induce PGP and downregulate OAT4 expression in vitro in human placental explants. Our findings suggest that the protective function of the placenta is compromised in women with PE and HIV with significantly altered expression of clinically important transporters. These translational studies provide key insight and real-world evidence of disease-mediated changes in placental transporter expression. As this may impact fetal health and increase in utero exposure to prescription medications, further studies and closer clinical investigation are needed to determine the impact of disease-induced changes on placental drug transporters and the possible impact on maternal drug-disposition and fetal drug exposure.

Keywords: BCRP
HIV
Placenta
Pre-eclampsia
Transporters
Advisor: Piquette-Miller , Micheline
Making Welfare Work for Autocracy: Wealth, Will Woes in the Politics of Welfare in China

China’s recent welfare expansion demonstrates a puzzling case. The welfare expansion has been broad-based, benefiting almost every sector of the society in one way or another, which is rare considering past authoritarian regimes often made welfare expansion exclusive to its loyal-support base. A wide degree of variation also exists in how welfare policies are prioritized in the shortterm and how welfare provision is made in the long-term. To address these puzzles, the study examines welfare expansion at the city-level, covering 114 cities from 2006 to 2016. The main arguments are three-fold. First, local leaders prioritize different welfare policies with different motivations. They prioritize education spending strategically, ensuring human development for the local economy’s productive purpose while enhancing prospects for personal promotion. By contrast, annual social security and total welfare spending are determined by the local state sector’s size. Second, the state sector also plays a critical role in determining long-term welfare provision. Cities with a large state sector tend to have a high level of welfare provision in the long-term. Finally, the state sector gained more than any other sector from the expansion of social security even though the general population experienced a relative improvement in their welfare. The findings underscore the importance of the state sector for regime survival. The expansion of the state sector is a culmination of past policies. While the state sector’s expansion had the goal of establishing its commanding presence in the market economy, on the political level, it became a vehicle for advancing the Party’s socialist agenda and establishing social stability. Moreover, the mixed-welfare system made the fiscal burden of welfare expansion bearable through standardization of social security, creating a large pool for contribution by socializing risk. Privileged benefit and coverage helped strengthen the Party’s patronage relation with the state sector, while the relative improvement in welfare provision for all helped gain broader legitimacy. As a result, the Party-regime made the welfare expansion work for its own survival interest by instrumentalizing welfare for mass-cooptation while making it affordable. The study establishes a clear link between welfare expansion, mass cooptation, and authoritarian-regime survival.

Keywords: Authoritarian Survival
China
Single-party Regime
Social Policy
Welfare Development
Welfare State
Advisor: Bertrand, Jacques J.B.
Towards the Controlled Synthesis of Conjugated Polymers

Organic semiconductors with varying physical and optoelectronic properties are readily obtained by incorporating different functional groups in conjugated polymers. While controlled chain-growth polymerization routes have been developed for a handful of these conjugated polymers, most conjugated polymers are still synthesized through step-growth methods that allow little to no control over the resulting polymers. Robust and versatile synthetic methodologies are needed to access conjugated polymers with unprecedented control and optimized properties. In Chapter 2, I describe a rapid and selective synthetic route to thionated naphthalene diimides (NDIs). Thionated NDIs exhibit improved electron mobilities and ambient stabilities. Thionation procedures, however, are lengthy, unselective, and low yielding. Polymeric analogues had not previously been reported due to incompatibilities between sulfur atoms and prevalent palladium catalysts. I illustrate that the rate and selectivity of thionation is drastically improved using steric control and highly efficient microwave irradiation. This methodology is readily applied to synthesize NDI-based polymers with varying degrees of thionation through post-polymerization modification. In Chapter 3, I investigate the anion-radical polymerization of parent and thionated, thiophene- and selenophene-flanked NDIs. Although NDI-based polymers exhibit among the highest electron mobilities for n-type conjugated polymers, their existing synthetic routes are still largely uncontrolled. Anion-radical polymerization provides a promising alternative, wherein thiophene- flanked NDIs have been shown to exhibit chain-growth polymerization. I show that thiophene- and selenophene-flanked NDIs undergo anion-radical polymerization, albeit through step-growth mechanisms. While thionated NDIs form anion-radical complexes and exhibit signs of catalyst insertion, they do not undergo further polymerization. In Chapter 4, I present the templated oxidative synthesis of conjugated polymers. Templated synthesis is a prevalent route to accessing biological and bioinspired polymers but has only sparingly been applied to the synthesis of conjugated polymers. I illustrate that well-defined macromolecular templates synthesized through ring-opening metathesis polymerization undergo subsequent oxidative coupling to form well-defined conjugated polymers. I apply this methodology to synthesize soluble, poly(3,4-ethylenedioxythiophene)-based polymers with controlled molecular weights and low dispersities. In Chapter 5, I summarize the main conclusions and outlook of this thesis work. Further optimization and expansion of the methodologies described herein could greatly impact the fields of conjugated polymers and organic electronic materials.

Keywords: conjugated
material
organic
polymer
semiconductor
Advisor: Seferos, Dwight S