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Engineering biochar-supported catalysts for efficient carbon dioxide methanation
No full textAs the concentration of CO2 in the atmosphere continues to rise, research into sustainable energy production
methods and the utilization of waste materials becomes paramount in limiting the increase of the earth’s
core temperature. Capturing and converting CO2 emissions into renewable natural gas, known as CO2
methanation, has been proven as an attractive method to both utilize CO2 emissions, and create renewable
fuels contributing to a circular economy. This process typically employs metal oxide catalysts which are
synthesized from raw materials and need to be disposed often due to deactivation. On the other hand,
biochar-supported catalysts have been proven for a variety of reactions and are investigated as an alternative
to conventional CO2 methanation catalysts in this study. Biochar-supported catalysts were synthesized and
tested as catalyst supports for CO2 methanation. The research was carried out in three phases: 1) biochar-
supported Ni catalyst production; 2) investigation of catalyst deactivation during CO2 methanation; and 3)
analysis of biomass properties on biochar catalyst activity. In the first phase, pyrolysis temperature was
varied from 400 – 600 °C, nickel was loaded on the biochar in the range of 5 – 10 wt.%, and methanation
temperature was investigated at 400, 500, and 600 °C. The support pyrolyzed at 500 °C, loaded with 10
wt.% Ni, and tested at 500 °C had the highest methane yield of 58%, yet deactivated rapidly over 5 hours
on stream. This motivated the second phase, where fresh and spent catalysts were characterized via BET,
XRD, SEM/EDX, and TPR. This analysis showed sintering of Ni particles as a major deactivation
mechanism of the supported catalyst. In the final stage, biochars were created from various feedstocks
including wheat straw, corn straw, bamboo, and birch bark. Inherent properties of the feedstock including
porosity, ash content and composition, and surface functional groups were found to significantly impact the
activity of the biochar as a support for catalytic methanation. Birch bark performance was superior with a
stable methane yield of 82% over 10 hours on stream. Inorganics were removed from bamboo biochar via
water or acid washing. The CH4 selectivity increased from 14% to 74% when water-soluble inorganics were
removed. When an acid wash was used, removing both acid-soluble and water-soluble inorganics, the
selectivity decreased to 17%. This suggests water-soluble inorganics hinder methanation and acid-soluble
inorganics support the reaction. Overall, biochar was proven to be a suitable catalyst support for CO2
methanation. The impact of biochar properties including porosity, inorganics, and Ni dispersion are shown
and quantified in order to provide recommendations towards the synthesis of efficient biochar-supported
catalysts for CO2 methanation.Alexandra Frainetti, 202
FACTORS THAT DETERMINE CHEMICAL REACTIVITY AND CONFORMATIONAL CHANGES OF A PEPTIDE IN AQUEOUS DROPLETS
No full textPlease modify the format of the abstract and lay summary if needed. Thank you.Aqueous nanodroplets containing ions and other reactive species are miniaturized reaction
chambers that drive important processes in atmospheric chemistry, aerosol formation,
and spray-based ionization technologies. It has been found experimentally by several
groups that aerosolization of bulk liquid into micrometre- or nanometer-sized droplets
accelerates the reaction rates by orders of magnitude relative to reactions in bulk. An airwater
interface of droplets forms a distinct domain characterized by density and charge
gradients, surface fluctuations, higher ion concentration, and solvent orientation. This
dissertation examines those potential factors contributing to the chemical reactivity of
droplets with ion pairing at 300 K and 200 K by using atomistic molecular dynamics and
enhanced sampling methods. The studied systems are negatively and positively charged
droplets of Na+/Cl– /OH– in aqueous droplets with a radius of up to a few nanometers.
The orientation of water solvent, coupled with radial charge density, is scrutinized for
characterizing droplet structure. The like-charged contact pairing is probed via umbrella
sampling. It is noted that handling the long-range electrostatic interactions is critical
in acquiring reliable data of charged droplets. To validate the electrostatic treatments
in spherical boundary conditions, which is required for the modelling, first, the study
of conformational changes of peptides under the multilevel summation method and direct
electrostatics is conducted. Further testing of electrostatic treatment is performed
on the onset and manifestation of charge-induced instability in dielectric subnanometer
droplets doped with a trivalent metal ion (La3+/Lu3+/Fe3+). Charge-induced instability
morphologies are addressed and confirmed with the temperature replica exchange
method.Han Ngo Nguyen, 202
Utilizing Mandarin textbooks Perceptions of teachers instructing Mandarin as a secondary language in Hong Kong
No full textThis case study examines teachers’ implementation of two Mandarin textbook series at a Hong Kong international school. Grounded in the Multiliteracies framework and the nested pedagogical orientations, the study conducted thematic analysis of curriculum documents and teacher interviews. Key findings reveal that although both textbooks emphasize speaking and reading, they underrepresent writing, listening, viewing, and visually representing skills, limiting culturally and linguistically diverse students’ expansive meaning-making options. Despite their heavy reliance on textbooks, teachers supplemented their instructions with multimodal resources and employed the social constructivist pedagogy to address diverse learners’ needs. The analysis reveals teacher-centered transmission models coexisting with social constructivist practices. However, transformative pedagogical approaches are notably absent. This study recommends that CSL/CFL pedagogical materials and practices incorporate multimodal, culturally responsive, and locally relevant approaches that empower learners as critical and engaged global citizens in international education contexts.Zhao Ning Qian,202
Neural Mechanisms of Adaptive Control in the Anterior Mid-Cingulate Cortex Across Negative Affect, Cognitive Control and Somatic Pain
No full textThe thesis cover page in the PDF document includes references to Western University’s previous institutional repository platform, known as Scholarship@Western, and links to that platform (beginning with ir.lib.uwo.ca). In citing or referring to this thesis, use the DOI or handle from this page instead. Sample citation: Author name, "Thesis title." (Year). Western University Open Repository. https://doi.org/10.71858/123456. Recent theoretical frameworks propose that adaptive control — the process by which individuals evaluate choices under uncertainty and voluntarily adjust behaviour to minimize potential harm and error — underpins anterior midcingulate cortex (aMCC) engagement across emotion, cognition and pain. However, empirical evidence remains limited. Using data from 23 healthy adults who underwent functional Magnetic Resonance Imaging (fMRI) while performing tasks probing negative affect, cognitive control and somatic pain, the present study tests aMCC activations and task-based connectivity patterns against specific predictions derived from the adaptive control hypothesis. Activation and connectivity analyses consistently supported adaptive control as an account of aMCC function. Cross-fitted three-layer dynamic causal modelling (DCM) revealed forward information flow from domain-specific inputs to the aMCC and higher- order regions in selected models for all tasks. These findings provide converging evidence for adaptive control as a unifying mechanism underlying aMCC engagement across emotion, cognition and pain, underscoring the value of network-level approaches in elucidating domain-general brain functions
Investigating the Potential Role of Organic Anion Transporting Polypeptides in Pancreatic Islets in Relation to Statin Therapy
No full textThis thesis is under embargo until July 31, 2026.Statin therapy has been associated with an increased new-onset type 2 diabetes (T2D) risk; however, underlying mechanisms remain unclear. Given that organic anion transporting polypeptides (OATPs) mediate statin uptake into the liver and other tissues, we hypothesized that Oatp1a/1b transporters may contribute to statin accumulation in the pancreas and impact insulin secretion. Accordingly, we examined Oatp expression in adult mouse pancreas and islets, assessed statin tissue distribution in Oatp1a/1b knockout mice, and performed in vitro uptake and functional islet assays. Oatp1a/1b gene expression was detected in the pancreas and islets. Compared to wildtype, Oatp1a/1b-deficient mice showed reduced pancreas-to-plasma ratios after oral atorvastatin, rosuvastatin, and pravastatin. We observed Oatp-mediated statin uptake in cell-based studies (HEK293T), and that rosuvastatin impairs insulin secretion in cultured primary mouse islets. Overall, our findings support an important role of pancreatic Oatps in mediating statin uptake and statin-associated islet dysfunction, offering mechanistic insight into statin-associated T2D risk.Chen Bei Hu, 202
Investigating the role of tau protein in a triple knock-in mouse model of Alzheimer's Disease.
No full textThere are many risk factors for Alzheimer’s Disease (AD) including the strongest genetic risk factor for late-onset AD (LOAD), the Apolipoprotein E4 allele (APOE4). This study investigates the effect of APOE4 on tau phosphorylation at Ser 202/Thr 205 and on cognition in the Paired Associates Learning (PAL) task in set of humanized mouse models of AD. Our findings show that there is phosphorylated tau in the cortex and hippocampus of 18-month-old mice, but the level of phosphorylation was not affected by APOE4. Furthermore, 12-month-old male mice had deficits in learning in the PAL task, and mice with both APOE4 and Aβ plaques showed decreased motivation to complete the task. Overall, these findings offer insights into the impact of APOE4 on tau phosphorylation and behavior in this mouse model.Jamie Fournier, 2025
Interaction Between Small Modular Reactors and Permafrost Rock
No full textThis study investigated the behaviour of frozen rock masses surrounding the foundation of small modular reactors (SMRs) in northern permafrost regions through physical modeling and finite element analysis. The physical models consisted of rock blocks separated by joints containing a fine-grained infilling. Digital image correlation results demonstrated consistent patterns of displacement under varying rock joint spacing and infilling conditions. Settlement adjacent to the SMR walls and heaving beneath were observed, attributed to melting and weakening of the joints. Horizontally, the rock mass tended to collapse inward toward the void, highlighting the importance of lateral support in SMR foundation design. Strain in horizontal and vertical directions revealed alternating bands of expansion and contraction due to the joint orientations at 0° and 90°.
The finite element analysis using software RS2 highlighted the role of thermosyphons, which transfer heat from the ground to the surface, stabilizing thermal conditions around SMR foundations. Models incorporating thermosyphons maintained ground temperatures close to surface air conditions (-26 to 15 °C) and stabilized deeper ground temperatures within five years. In contrast, models without thermosyphons exhibited continual temperature increases over 15 years. By mitigating warming of the surrounding rock mass, thermosyphons reduce risks of structural failure and excessive maintenance costs, improving the feasibility of SMR use in permafrost regions.
This study contributes preliminary data on deformation behaviour in thawing rock masses. Furthermore, it demonstrates the effectiveness of thermosyphons in preserving thermal and structural stability of permafrost rock. Together, these findings address critical knowledge gaps in SMR installation and support the advancement of low-emission, resilient energy systems for northern communities in Canada.Noah Frymire, 202
Genetics and Politics: Trait Foundations, Technological Advances, Health & Privacy
No full textPolitical psychologists examine individual differences and human universals in their understanding of psychological processes in political orientations, attitudes, and behaviors. Whether they study emotion, cognition, or personality, scholars assume states and traits have some basis in individual dispositions. The origin, formation, and development of these dispositions may come from genetic or environmental sources but much fewer political psychologists undertake these foundational studies. While most areas of political psychology have proliferated across our discipline, genetic studies have lagged behind. Access to genetic data and genetically-informed samples is limited, costly, and often proprietary, creating natural barriers for advancing this study. In addition, scholars may need to learn new methodologies in order to integrate genetic data into their own work. But as we argue below, genetic influences and understandings of politics are more than just twin studies and vital pieces of the puzzle to understanding the psychological underpinnings of political behavior. In this chapter, we explore five topics. First, we discuss the value of genetics for political science and how political science has contributed to understanding public attitudes regarding heritability. Second, we examine in more detail the use of twin and family models in political science, highlighting methods beyond estimating heritability for political traits, such as techniques that focus on covariation with other traits, longitudinal direction of causation models, and co-twin control designs. Third, we review the use of genome wide association studies in political science and examine the potential uses of polygenic indices in future studies. Fourth, we discuss how the regulation of genetic influences by epigenetic factors has been studied elsewhere in the social sciences and could be applied to political science research. Fifth, we explore how political psychologists could contribute to the study of public attitudes towards developments in the field of human genomics, such as genetic security and privacy attitudes, public opinion on personalized medicine and other use cases for genetics, and public responses to genetic ancestry testing
An in-depth analysis of Apollo 66075: clast petrography, geochemistry, and deformation
No full textSample 66075 is an impactite collected during the Apollo 16 mission and has since been referred to by several classifications throughout literature, most frequently, “ancient” regolith breccia. Since the classification of the Apollo samples, our knowledge of impactites has improved, as evidenced by the usage of outdated nomenclature. Implementing the newly proposed impactite classification scheme for the Artemis 3 mission, four thin sections of 66075 were studied in detail via optical microscopy, micro-XRF, EPMA, and micro-XRD to determine whether it requires reclassification. We identified a diverse range of clast types sourced from all highlands geochemical suites and the lunar mare, most notably, the first instance of a dunite clast in an Apollo 16 breccia. Additionally, it contains igneous clasts that have experienced a range of shock pressures from ~5 to ~22 GPa. Having not identified agglutinates, 66075 is likely an impact melt-bearing breccia as opposed to a regolith breccia.Marc Mechem, 202
BOLD Signal Variability as a Clinical Biomarker of Normative Pediatric Neurodevelopment
No full textThis thesis is under embargo until January 24, 2026.Understanding normative brain development is essential for identifying early markers of neurodevelopmental risk. Variability in the functional MRI signal, measured as BOLD signal standard deviation (BOLDSD), deviates in atypical development, making it a promising biomarker. This thesis characterized whole-brain and region-specific BOLDSD in children aged 3–13 and evaluated its clinical utility. Preprocessed gray matter, white matter, and cerebrospinal fluid signals were analyzed using dimensionality reduction and regression approaches. Three models were produced, revealing distinct patterns of variability across development. A key finding was a parabolic trend in global BOLDSD, with variability decreasing until late childhood, and increasing thereafter, consistent with known maturational processes. Additionally, a negative association was observed between BOLDSD and the gray-to-white matter ratio, suggesting a link between structural and functional development. These results support BOLDSD as a sensitive index of brain maturation and highlight the need for longitudinal and clinical validation to advance early neurodevelopmental risk detection