VictorJuiz/thesis huggingface dataset:
Hydrogen Production using Catalytic Supercritical Water Gasification of Lignocellulosic Biomass

Catalytic supercritical water gasification (SCWG) is a promising technology for hydrogen and methane production from wet organic feedstocks at relatively low temperatures (e.g. <500 oC). However, in order to make this process technically and economically viable, solid catalyst with enhanced activity and improved hydrogen selectivity should be developed. In this study, different aspects of catalytic SCWG have been investigated. The performance of several supported-nickel catalysts were examined to identify catalysts that lead to high carbon conversion and high hydrogen yields under near-critical conditions (i.e. near 374 oC). Moreover, for the first time, the effects of several parameters which dominated the activity of the supported nickel catalysts have been systematically investigated. Among the several different catalyst supports evaluated at 5% nickel loading, α-Al2O3, carbon nanotube (CNT), and MgO supports resulted in highest carbon conversions, while SiO2, Y2O3, hydrotalcite, yttria-stabilized zirconia (YSZ), and TiO2 showed modest activities. Comparing the XRD patterns for the support materials before and after the exposure to supercritical water, α-Al2O3, YSZ, and TiO2 were found to be hydrothermally stable among the metal oxide supports. Using the same amount of nickel on α-Al2O3, the methane yield decreased by increasing the nickel to support ratio whereas the carbon conversion was only slightly affected. At a given nickel to support ratio, a threefold increase in methane yield was observed by increasing the temperature from 350 to 410 oC. The catalytic activity also increased by the addition small quantity of potassium. The activity of Ni/γ-Al2O3 catalyst varied based on the affinity of the catalyst to form nickel aluminate spinel. This is also the first report on the role of oxidative pretreatment of the carbon nanotubes by nitric acid on the performance of these catalysts for the supercritical water gasification process. Using different lignocellulosic feeds, it was found that the gasification of glucose, fructose, cellulose, xylan and pulp resulted in comparable gas yields (± 10%) after 60 min, whereas alkali lignin was substantially harder to gasify. Interestingly, gasification yield of bark, which had a high lignin content, was comparable to those of cellulose. In summary, the Ni/α-Al2O3 catalyst had a higher hydrogen selectivity and comparable catalytic activity to the best commercially available catalysts for SCWG of carbohydrates.

Keywords: Catalyst
Gasification
Biomass
Supercritical water
Advisor: Farnood, Ramin
An Investigation into Cis-elements, Rare Mutations, and Slipped-DNA Detection at Trinucleotide Repeat Disease-associated Loci

Gene-specific trinucleotide repeat expansions are the cause of an ever-growing number of disorders, including myotonic dystrophy type 1 (DM1) and spinocerebellar ataxia type 7 (SCA7). Both DM1, and SCA7 are characterized by large differences in repeat numbers between tissues that are differentially affected, indicating tissue-specific mechanisms of repeat instability. The mechanism(s) of both somatic as well as germline instability are complex and still poorly understood, with evidence supporting the contribution of cis-elements, trans factors, and DNA metabolic processes that are hypothesized to involve alternative structure formation within the DNA tract. This thesis involves investigations into the role of a particular cis-element (CTCF) on instability, as well as the detection of slipped-DNAs in patient tissues and the presence of rare mutations within those same tissues. Here I identify the first endogenous cis-element reported to show regulation of instability at a trinucleotide repeat disease locus, the DNA binding site for the insulator protein CCCTC- binding factor (CTCF) downstream of the SCA7 repeat. Using a mouse model with a mutation in the CTCF binding domain, I show that the loss of CTCF binding stimulates germline and somatic instability in a tissue-specific and age-dependent manner. The binding of CTCF likely protects the repeat tract from expansion by shielding it from other elements that may contribute to expansion. DNA metabolic processes such as replication, repair, and transcription likely play a role in repeat expansion at disease loci, with the general mechanism hypothesized to be the extrusion and aberrant repair of slipped-DNA structures during the unwinding process for each. While characterizing DM1 patient tissues in order to isolate slipped-DNA structures, I characterized two non-CTG repeat insertion mutations that had completely replaced the repeat tract in a small subset of cells in only two tissues in one patient. Given the hypermutable nature of expanded repeat tracts, it is possible that these types of mutations are more common than suspected. Finally, I report on the detection and isolation of slipped-DNA structures from the endogenous DM1 locus from patient tissues. The slip-outs appear as clusters along a length of DNA, rather than single isolated slip-outs, and more unstable tissues contain greater amounts of slipped-DNA compared to more stable tissues. This detection implies that slipped-DNA structures are not merely transient intermediates in the mutation and expansion process as has long been assumed, but remain within the DNA at detectable levels. The data reported herein both furthers our understanding of trinucleotide repeat instability, and additionally confirms the decades-long hypothesis that slipped-DNAs are in fact forming in patient tissues in a tissue-specific manner.

Keywords: human genetics
trinucleotide repeats
Advisor: Pearson, Christopher E.
Evaluation of the Use of a Bioengineered Hydrogel Containing Hyaluronan to Reduce Inflammation and Scarring following Spinal Cord Injury Associated with Arachnoiditis

Background: Spinal cord injury (SCI) is heterogeneous in nature and can be complicated by inflammation and scarring in the subarachnoid space (arachnoiditis). The constellation of traumatic injury and arachnoiditis can lead to extensive intraparenchymal cysts or post-traumatic syringomyelia (PTS), due to alterations in fluid flow and pressure dynamics in the subarachnoid space. Hypothesis: Intrathecal injection of a bioengineered hydrogel containing hyaluronan (HA) will improve functional recovery following severe spinal cord injury associated with arachnoiditis. Methods: Acute to subacute pathophysiological events were characterized in non-injured sham rats, rats receiving a clip compression/contusion injury (SCI), rats receiving an intrathecal kaolin injection (Arachnoiditis) and in rats receiving SCI plus kaolin injection (PTS). Next, a HA containing hydrogel (HAMC) or artificial cerbralspinal fluid (aCSF) control was injected into the subarachnoid space 24 hours following PTS injury. To assess treatment efficacy, subacute pathophysiology was assessed as was long-term neurobehavioural and neuroanatomical recovery. Finally, in vitro studies examined the effect of HA on TLR4 activation using lipopolysaccharide in primary rat microglial cultures. Results: PTS animals exhibited a greater parenchymal injury response as compared to the sum of SCI alone or arachnoiditis alone. Injection of HAMC reduced the extent of scarring and inflammation in the subarachnoid space and improved neurobehavioural and neuroanatomical recovery relative to aCSF controls. These improvements were associated with reduced chondroitin sulfate proteoglycan and IL-1α expression and a trend towards and axonal preservation. In vitro studies demonstrated that HA is capable of reducing TLR4 mediated inflammation in microglia. Conclusions: Acute arachnoiditis potentiates the intensity of intraparenchymal inflammatory and scarring events following SCI. When HAMC was injected intrathecally following PTS injury, it mitigated some of the pernicious effects of arachnoiditis. Part of the therapeutic action of HAMC can be attributed to the ability of HA to reduce TLR4 mediated inflammation in microglia, possibly through an extracellular mechanism.

Keywords: Spinal cord injury
Inflammation
Microglia
Hyaluronan
Arachnoiditis
Post-traumatic syringomyelia
Scarring
Advisor: Fehlings, Michael G.
Surviving Success, Reconciling Resilience: A Critical Analysis of the Appearance of Student ‘Mental Life’ at one Canadian University

This dissertation addresses the university student as a figure of mental health and illness. Drawing on the methods and theories of disability studies, interpretive sociology, critical, feminist and queer theory, as well as hermeneutically oriented phenomenology, my work explores the social production of this student figure or type – variously depicted as ‘ invisible’, ‘maladjusted’, ‘stressed’, ‘difficult’, sensitive’, ‘resilient’, ‘narcissistic’, and extraordinarily ‘ordinary’. This figure is addressed as a means of revealing contradictory understandings of the relationship between success and survival, as this relationship appears in the ordinary daily life of the University of Toronto, Ontario, Canada. The social and historical significance of the contemporary University’s Student Life Programs and Services is analyzed with a view to reveal the Western cultural values and practices which organize consciousness of success as a necessary condition of contemporary existence. Special attention is paid to the cultural production of knowledge concerning university student ‘mental life’, the appearance of which is located at the interstices of colonialism, global health policy, institutional ‘best practices’, cultural mores and folkways, and embodied experiences. I dwell with this appearance as an occasion to engage the materiality of Western mythologies of resilience, and with them the meaning of human agency under neoliberal governance. This engagement examines the productive power of the disciplinary and institutionalized ‘language of mental illness’ through a genealogy of the University of Toronto, a textual analyses of the University’s Student Life Programs and Services literature, and a discursive analysis of open-ended interviews with student services representatives which seeks both to understand and transgress conventional interpretations of the structure of Student Life. I demonstrate how University presentations of student bodies, minds and senses perceived to be lacking in ‘ordinary order’, can be reconceived as sites to reflect on the paramount presence of psychiatric knowledge in interpretations and responses to embodied difference within the university setting. Overall, this dissertation seeks to disrupt unexamined relations to the meaning of student types; and in the process, display how normative relations to the student as a figure of mental health and illness needs is currently and historically organized and socially achieved.

Keywords: sociology of higher education
critical disability studies
phenomenology
social theory
women and gender studies
university student mental life
Advisor: Titchkosky, Tanya
Reactivity of Aziridine Aldehyde Dimers and their Utility in the Synthesis of Peptidomimetics

Amino aldehydes are important building blocks in organic synthesis. However, due to the innate propensity for condensation to occur upon combination of aldehydes and amines, uprotected amino aldehydes are unstable. One exception to this is the existence of dimeric aziridine aldehydes. We have shown that the enhanced stability observed with these unprotected aziridine aldehydes is due to their dimeric nature. In addition, we have shown that reversible dimer dissociation plays a key role in the kinetics and stereoselectivity of subsequent reactions. Reductive amination with the unprotected amino aldehyde dimers occurs without double addition or epimerization. The resulting aziridine conjugates were used towards a convergent synthesis of aminomethylene peptidomimetics, by aziridine ring opening with C-terminal peptide thioacids. We have shown that we can also utilize the aziridine aldehydes towards the assembly of branched peptides.

Keywords: peptide
ligation
amino aldehyde
Advisor: Yudin, Andrei
Retroflex Consonant Harmony in South Asia

This dissertation explores the nature and extent of retroflex consonant harmony in South Asia. Using statistics calculated over lexical databases from a broad sample of languages, the study demonstrates that retroflex consonant harmony is an areal trait affecting most languages in the northern half of the South Asian subcontinent, including languages from at least three of the four major families in the region: Dravidian, Indo-Aryan and Munda (but not Tibeto-Burman). Dravidian and Indo-Aryan languages in the southern half of the subcontinent do not exhibit retroflex consonant harmony. In South Asia, retroflex consonant harmony is manifested primarily as a static co-occurrence restriction on coronal consonants in roots/words. Historical-comparative evidence reveals that this pattern is the result of retroflex assimilation that is non-local, regressive and conditioned by the similarity of interacting segments. These typological properties stand in contrast to those of other retroflex assimilation patterns, which are local, primarily progressive, and not conditioned by similarity. This is argued to support the hypothesis that local feature spreading and long-distance feature agreement constitute two independent mechanisms of assimilation, each with its own set of typological properties, and that retroflex consonant harmony is the product of agreement, not spreading. Building on this hypothesis, the study offers a formal account of retroflex consonant harmony within the Agreement by Correspondence (ABC) model of Rose & Walker (2004) and Hansson (2001; 2010). Two Indo-Aryan languages, Kalasha and Indus Kohistani, figure prominently throughout the dissertation. These languages exhibit similarity effects that have not been clearly observed in other retroflex consonant harmony systems; retroflexion is contrastive in both non-sibilant (i.e., plosive) and sibilant obstruents (i.e., affricates and fricatives), but harmony applies only within each manner class, not between them. At the same time, harmony is not sensitive to laryngeal features. Theoretical implications of these and other similarity effects are discussed.

Keywords: Phonology
Retroflex
Consonant Harmony
Assimilation
South Asia
Indo-Aryan
Dravidian
Munda
Advisor: Rice, Keren
The Implications of Developmental and Evolutionary Relationships between Pancreatic Beta-cells and Neurons

A pancreatic stem cell could provide the tissue necessary for widespread β-cell transplantation therapy for diabetes. It is disputed whether pancreatic stem cells or β-cell replication are responsible for maintenance and regeneration of endocrine cells. Evidence presented here shows that pancreatic stem cells express insulin and produce multiple endocrine, exocrine and neural cells in vitro and in vivo. The human pancreas also contains stem cells that produce functional β-cells capable of reducing blood sugar levels in a diabetic mouse. Initial studies of pancreatic stem cells grown clonally in vitro indicated that they produced large numbers of neurons, suggesting they may be derived from the neural crest. Evidence shows that there are at least two distinct developmental origins for stem cells in the pancreas; one from the pancreatic lineage that produces endocrine and exocrine cells and one from the neural crest lineage that produces neurons and Schwann cells. Furthermore, pancreatic stem cells require the developmental transcription factor, Pax6, for endocrine cell formation suggesting they are using expected differentiation pathways. There is an interesting evolutionary connection between pancreatic β-cells and neurons which was applied to the derivation of pancreatic stem cells from human embryonic stem cells by using a clonal neural stem cell assay. These pancreatic stem cells express pancreatic and neural markers, self-renew and differentiate into insulin-expressing cells. The overexpression of SOX17 in these cells increases stem cell formation and self-renewal but inhibits differentiation. Overall I will show that there is a genuine stem cell in the adult mammalian pancreas capable of producing functional β-cells, that this stem cell is derived from the pancreatic developmental lineage but the pancreas also contains stem cells from the neural crest lineage, and that the neural stem cell assays that have identified these adult stem cells can be applied to the derivation of a pancreatic stem cell from hESCs.

Keywords: stem cells
pancreas
neural crest
Advisor: Kooy, Derek van der
Why AIM? - Educator Perspectives and Implementation of an Instructional Method for Teaching Core French as a Second Language in Ontario

Since 2003, the Canadian government has repeatedly called for research into innovative ways to teach Core French (CF) – a non-immersion program, where French as a Second Language (FSL) is taught on a daily basis, or a few times per week. This exploratory study investigates the driving forces behind the widespread popularity of a CF method called the Accelerative Integrated Method (AIM), which combines target language use with gestures, high-frequency vocabulary, and drama to accelerate the development of fluency from the onset of classroom instruction. In order to learn more about the “meaningfulness” of this growing trend (Fullan, 2007), this mixed-method inquiry attempts to shift the focus from product to process, comparing educator perspectives and AIM implementation within two Ontario contexts: (a) where AIM was mandated for elementary (Grades 4-6) FSL instruction, and (b) where AIM was an optional method for FSL teachers to use (or not). Survey and interview data were collected from and triangulated across a variety of educators from both contexts, including FSL consultants (n = 18), principals (n = 8), CF teachers (n = 9), and one Ontario Ministry of Education representative. Four semi-structured interviews and multiple observations were also conducted with those CF teachers who were using AIM (n = 8). An additional CF teacher who had attempted to use AIM, and had subsequently rejected it, was also interviewed. Findings showed that AIM implementation and educator perspectives did not vary significantly based on whether AIM was mandated or optional for CF instruction. A clear preference emerged towards using AIM and the accompanying resources during the beginning stages of CF instruction. Discussion about the growing popularity of AIM was positive; however, it also exposed a range of emotions about when and how AIM should be used. In terms of implementation, while some AIM routines, activities, and strategies were used by all, each AIM teacher exercised their agency while using the method, supplementing and adapting for different reasons. Implications include the need to reexamine the objectives of micro-level AIM policies, recognize the adaptability of AIM, and consider including detailed observations in future research linking AIM to student achievement.

Keywords: second language teaching
French as a second language (FSL)
Core French
Accelerative Integrated Method (AIM)
instructional method
educational change
agency
Advisor: Gagne, Antoinette
The Principle of Coordinate Invariance and the Modelling of Curved Material Interfaces in Finite-difference Discretisations of Maxwell's Equations

The principle of coordinate invariance states that all physical laws must be formulated in a mathematical form that is independent of the geometrical properties of any particular coordinate system. Embracing this principle is the key to understand how to systematically incorporate curved material interfaces into a numerical solution of Maxwell’s equations. This dissertation describes how to generate a coordinate invariant representation of Maxwell’s equations in differential form, and it demonstrates why employing such representation is crucial to the development of robust finite-difference discretisations with consistent global error properties. As part of this process, two original contributions are presented that address the issue of constructing finite-difference approximations at the locations of material interfaces. The first contribution is a domain-decomposition procedure to enforce the tangential field continuity conditions with a second-order local truncation error that can be applied in 2-D or 3-D. The second contribution is a similar domain-decomposition procedure that enforces the tangential field continuity conditions with a local truncation of order 2L—where L is an integer greater or equal to one—but that can only be applied in 1-D. To conclude, the dissertation also describes the interesting connection that exists between the use of a coordinate invariant representation of Maxwell’s equations to design artificial materials and the use of the same representation to model curved material interfaces in a finite-difference discretisation.

Keywords: numerical techniques
finite-difference methods
material boundaries
material interfaces
artificial materials
metamaterials
FDTD
high-order methods
Advisor: Sarris, Costas D.
Health Services Utilization among Persons Living with Human Immunodeficiency Virus Infection in Ontario

The goals of this dissertation were to investigate aspects of the health services utilization of marginalized persons living with HIV (PLWH), including women, recent immigrants, heterosexual men and individuals living in low income neighborhoods. In the first study, an algorithm of three physician claims for HIV-infection within a three-year period was validated for case-ascertainment of PLWH in administrative databases. The sensitivity and specificity of the algorithm were 96.2% [95% confidence intervals (CI) 95.2% to 97.9%] and 99.6% (95% CI 99.1% to 99.8%), respectively. The algorithm was used to conduct a population-based study examining rates of hospitalization among all PLWH receiving care in Ontario. The introduction of combination antiretroviral therapy was associated with more pronounced reductions in rates of total (-89.9 vs. -60.5 per 1000 PLWH; p = 0.003) and HIV-related hospitalizations (- 56.9 vs. -36.3 per 1000 PLWH; p < 0.001) among men relative to women. Between 2002 and 2008, higher rates of total hospitalization were associated with female sex [adjusted relative rate (aRR) 1.15; 95% CI: 1.05 to 1.27] and low socioeconomic status (aRR 1.21; 95% CI: 1.14 to 1.29). Higher rates of HIV-related hospitalizations were associated with low socioeconomic status (aRR 1.30; 95% CI: 1.17 to 1.45). Recent immigrants had lower rates of both total (aRR 0.70; 95% CI 0.61 to 0.80) and HIV-related hospitalizations (aRR 0.77; 95% CI 0.61 to 0.96). Finally, a theoretically-informed qualitative study was conducted to characterize the help-seeking experiences of heterosexual men living with HIV. The results indicate that without the symbolic appeal of women and the social connections of gay men, heterosexual men lack the composition of capital required to benefit fully from or improve their positions within the existing HIV health and social service fields. The findings of this dissertation illustrate important disparities in health services utilization among PLWH in Ontario.

Keywords: clinical epidemiology
health services research
Advisor: Glazier, Richard H.