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Physicochemical characterization and surface reactivity of natural pyrogenic carbon and its role in metals and nutrients transport
No full textWildfire-derived pyrogenic carbon (F-PyC) is produced in immense quantities, up to 385x109 kg, each year and yet it has studied far less than its commercially-produced counterpart, biochar (B-PyC). While B-PyC dominates the literature, its physicochemical properties and behaviour in the environmental differ significantly from F-PyC, raising concerns about its use as a proxy. This dissertation addresses critical gaps in the formation, reactivity, and nutrient and metals transport potential of F-PyC, particularly in fluvial systems, and evaluates whether B-PyC is an appropriate proxy as has been proposed in the past. Firstly, the "B-PyC proxy problem" is addressed through leaching experiments that reveal the unique role of F-PyC’s inorganic ash fraction in elemental cycling. The findings demonstrate that B-PyC and F-PyC have substantially different physicochemical properties, resulting in differing elemental transport potential, thus proving that slow-pyrolysis B-PyC is not a suitable proxy for F-PyC. Concluding this, F-PyC reactivity is then tested to determine how F-PyC participates in reactive transport processes in freshwater fluvial systems, with implications for contaminant mobility and nutrient cycling following wildfire events. Finally, the effect of pyrolysis intensity, quantified as the average maximum temperature (AMT), char intensity (CI), and peak derivative thermogravimetric temperature (DTG), on the physicochemical properties of F-PyC was tested. It was determined that while no single temperature-derived metric fully captures the F-PyC physicochemical properties, combining several analytical approaches promises to provide insight into its reactivity, elemental composition, and surface chemistry and thus resultant transport potential. These results underscore the need to incorporate F-PyC explicitly into geochemical and reactive transport models, especially in wildfire prone regions such as western Canada. Recommendations for future research include studies on marine systems, weathered and colloidal F-PyC, groundwater\ninteractions, and reconstructing wildfire intensity from F-PyC properties. As wildfire regimes shift with climate change, understanding the unique behavior of F-PyC is critical to predicting its role in elemental cycling and contaminant transport on a global scale. This research establishes a foundation for a new generation of F-PyC studies that reflect the complexities of real-world fire conditions, moving beyond the simplified B-PyC paradigm that now dominates the literature
Coarse-Grained Molecular Dynamics Study on Polyethylenimine-Based Nanoparticles for Pulmonary Gene Delivery: From Model Development to Surfactant Crossing Simulation
No full textPulmonary gene delivery has demonstrated high specificity for respiratory diseases, offering precise control over therapeutic dosage and side effects. However, intrinsic barriers within the pulmonary system, such as crossing the pulmonary surfactant and evading mucus entrapment, present significant challenges. The distinct hydrophobic properties of the plasma membrane and pulmonary surfactant necessitate tailored chemistries of gene carriers to enhance delivery efficacy. Large-scale CG molecular dynamics simulations provide a powerful tool for screening gene carriers and understanding the molecular mechanisms underpinning pulmonary delivery. Among non-viral carriers, PEI has emerged as a promising candidate due to its tunable molecular weight, degree of branching, and functionalization. This thesis focuses on developing Martini-compatible CG models for PEI and its lipid-substituted variant, PEI-CA, to simulate PEI-based NPs in pulmonary gene delivery. The CG models were constructed by determining both bonded and nonbonded interaction parameters, with particular emphasis on ensuring compatibility with Martini siRNA, and key pulmonary surfactant components such as DPPC and DPPG. A three-stage parameterization strategy was employed to align AA and CG PMF calculations: (1) uncharged PEI, (2) charged PEI without lipid substitution, and (3) PEI-CA. The final optimized parameters produced relative differences between AA and CG PMFs that were comparable to or smaller than those reported in Martini literature, validating the models for further study.
Using these validated CG models, the pulmonary environment was created, consisting of a DPPC and DPPG monolayer under constant surface tension. siRNA/PEI-CA and siRNA/PEI NPs were pulled toward the pulmonary monolayer across ten systems: five with siRNA/PEI-CA and five with siRNA/PEI at surface tensions of 10, 15, 20, 25, and 30 mN/m. Force analysis revealed that increasing surface tension reduced the force required to pull the NPs toward the monolayer. NP integrity, assessed through Rg calculations, consistently decreased during pulling, with more reductions at higher surface tensions. Monolayer integrity, analyzed via pore ratios before and after NP crossing and during recovery simulations, showed significant monolayer disruption in post-crossing, with minimal pore ratio decrease during recovery. The Martini-compatible CG models and insights from these NP-monolayer interactions establish a solid foundation for future simulations of PEI- and PEI-CA-based pulmonary gene delivery systems
Returning to the ‘homeland’: South Asian Punjabi-speaking families attitudes and practices towards heritage language maintenance in Edmonton, Alberta
No full textThis study explores how South Asian Punjabi-speaking families in Canada maintain their heritage language within an English-dominant society. Despite projections that nearly half of Canada’s population will be first- or second-generation immigrants by 2031, research on heritage language maintenance (HLM) among Punjabi-speaking communities—particularly in Edmonton, Alberta—remains limited. Drawing on multiple theoretical perspectives, the study examines how personal experiences, language ideologies, and linguistic identities intersect with power, family, and community life to shape HLM practices.
Methodologically, the research combines reflective journaling, semi-structured interviews, and engagement with both academic and community sources to capture authentic perspectives. Findings highlight the importance of translanguaging, community collaboration, and culturally grounded approaches in fostering language retention. The study underscores the role of educators, families, and community networks in promoting language diversity, supporting inclusive educational practices, and informing policy to make Punjabi language learning accessible and meaningful for diasporic communities
Dissipation induced by libration in fluid planetary cores
No full textWe present a study of the dissipation in the internal rotating fluid layers of planets that results
from fluid motions driven by viscous coupling to a solid region of the planet undergoing libration.
The latter refers to the variation of the spin rate and orientation of the spin axis of a planet
due to gravitational torques from a parent body. Some planetary bodies such as Mercury, the
Moon and some satellites of Jupiter and Saturn which contain global internal fluid layers, either
molten cores or subsurface oceans, also undergo observable gravitational librations which drive fluid
motions in these internal layers. The flows driven in these layers represent a potentially significant
source of dissipation; rotational energy is transferred to fluid motion that eventually dissipates as
heat, or contributes to sustaining a magnetic field influencing the long-term evolution of both the
spin-orbital dynamics of the system and the thermal and magnetic history of the body.
In the first part of our study, we focus on completing a linear theory of the excitation of inertial
wave modes in rapidly rotating spheres by viscous forcing and evaluating the dissipation of the
resulting matched asymptotic solution. We find that, due to the scaling of the Ekman layer, the
dissipation dominantly scales with Ek^1/2, where Ek is the Ekman number that quantifies the ratio
of viscous forces and Coriolis force on the fluid. Furthermore, when the frequency of the forcing
matches the natural frequency of an inertial mode, the dissipation is decreased by as much as 9%
by the influence of the mode.
In the second part of our study we present the results of a numerical linear stability analysis
of axisymmetric perturbations to the linear base flow considered in the first part. We isolate the
conditions for the development of a boundary layer instability and measure systematic trends among
the growth rates as a function of Ek, and a local Reynolds number Re = ε/Ek^1/2, where ε is the
non-dimensionalized forcing amplitude of the libration. For the base flow induced by longitudinal\nlibrations in a spherical shell, we find the boundary layer instability onset is around Re ∼ 30 − 50
for the Ekman numbers that we considered, 10^−4.6 ≤ Ek ≤ 10^−3.8; our results align with those
obtained by other studies that used numerical simulations.
Our results lay the groundwork for future investigations into related flows induced in planetary
fluid layers. Utilizing the linear theory and numerical methods developed in the first part to study
flow driven by the axisymmetric longitudinal librations in fluid spheres, we could also conduct an
investigation into dissipation in the flow driven by latitudinal libration. Furthermore, the numerical
method can be extended to study dissipation in spherical shells, and boundary conditions can be
adapted to model topographical forcing, in addition to viscous coupling. The method developed
in the second part will be deployed in a large suite of calculations that cover the full parameter
range for the spherical shell, and including all forcing frequencies and a broader range of Ekman
numbers. The insights gained into frequency or geometry dependent effects on the instability will
inform investigations using fully nonlinear numerical simulations
Incentivizing Virtual Power Plant Participation via Shapley Value Rewards
No full textThe rise of distributed energy resources (DERs) and bidirectional electricity trading is transforming energy markets, enabling small- and medium-scale generators to actively participate through new aggregation mechanisms. Virtual Power Plants (VPPs) address this need by bundling multiple DERs into a single market participant, improving forecasting accuracy and mitigating exposure to market penalties. A central challenge, however, lies in designing a revenue-sharing mechanism that is fair, incentive-compatible, and attractive to both DERs and the aggregator.
This paper proposes a Shapley value-based payment mechanism that ensures individual rationality - every DER benefits from joining - and incentivizes truthful reporting of forecasts. Unlike prior approaches centered on maximizing social welfare, we model the VPP as a profit-driven agent that retains a fair share of revenues while still improving overall coalition performance.
We analyze the mechanism under competitive market conditions, offering both theoretical guarantees and empirical evidence. Our results demonstrate that the Shapley mechanism outperforms scoring rule-based payments in terms of fairness and profitability. Finally, we show that portfolio diversification consistently boosts profits, and both DERs and the VPP prefer Shapley-based allocation under all levels of correlation in generation profiles
The Intersection of Work and Care: Exploring the Facilitators and Barriers of Maternal Employment in Canada
No full textSince the 1970s, many OECD countries have seen a significant increase in maternal employment rates. In cross-national comparison, Canada has high maternal employment rates, but lags behind some Nordic and East European countries. Within this context, this study explores how larger social, cultural and policy environments shape mothers' employment experiences, challenging the notion that women prefer to opt out of the labour force when they have children To conduct this analysis, I drew on focus groups (n=19) and individual interviews (n=39) with 58 mothers in Canada with preschool children in the province of Alberta. The key finding from this study was that the majority of mothers, despite wanting to continue their careers alongside parenthood, experienced challenges integrating unpaid and paid work. To navigate these challenges, mothers employed various strategies, including seeking flexibility at work, reducing work hours, or opting out of employment. Yet, many remained ambivalent regarding their employment arrangements. I detail the ways in which paid parental leave and childcare policies acted as facilitators or barriers to mothers’ labour force participation. Overall, the findings indicate that current policies are not sufficient to support mothers in the labour force. This study adds to a body of Canadian literature that examines how barriers such as pervasive gender norms in the workplace and households, and workplace inflexibility, create barriers to mothers’ labour force participation and impact mothers’ experiences in the labour market
Altering the Thermodynamics of Non-Oxidative Coupling of Methane Using Molten Fluoride Salt Mixtures
No full textMethane–the main constituent of natural gas- is abundant, inexpensive, widely burned for heat and power and still flared or vented on the order of 1011 m3/year, wasting its chemical value and adding CO2 to the atmosphere. Due to its strong C–H bond (~440 kJ mol⁻¹), direct chemical upgrading of CH4 remains difficult. In current industrial practice, methane is primarily utilized through combustion or indirect conversion methods such as steam-methane reforming (followed by the water-gas shift) that yields hydrogen but consumes ~10.3 GJ per tonne of CH4 and produces a significant carbon footprint. “Direct” valorization routes have been explored, each with a set of critical challenges: oxidative coupling of methane (OCM) consumes O2 and inevitably releases CO2, while methane pyrolysis avoids CO2 but generates roughly three tonnes of solid carbon per tonne of H2—far more than the carbon-black market can absorb. Against this backdrop, direct valorization of methane through the non-oxidative coupling reaction (NOCM,2 CH4 → C2H4 + 2 H2) provides a single-step, CO2¬ free route to higher value chemicals but the gas-phase thermodynamics are strongly uphill (ΔG° ~ +132 kJ mol⁻¹ at 850 K). While most studies on NOCM have focused on altering reaction kinetics through catalyst design, the underlying thermodynamic limitation remains largely unaddressed. This thesis investigates how high-temperature molten fluoride salts can lower that thermodynamic limitation enabling CH4 conversions above 25% at 900–1000 °C and offering a solvent-assisted route to low-carbon hydrogen and ethylene. When NOCM is made thermodynamically feasible, it can deliver the products of higher value at only a third of their energy requirements, instead of the industrial energy demand currently.
This study examines how molten fluoride salts at high temperatures can reduce that thermodynamic limitation. Initially, three eutectic melts— FLiBe (LiF-BeF2), FLiNaK (LiF-NaF-KF), and FLiNaBe (LiF-NaF-BeF2)—were simulated with a polarizable SEM–Drude force field whose non-bonded parameters for H2, CH4 and C2H4 were fitted to first-principles interaction energies, which were later extended to eight other alternate eutectic melts. The model reproduces experimental densities, radial distribution functions and published hydrogen Henry constants within four percent error over the 673–1773 K range. Slow-growth thermodynamic integration (TI), refined with Bennett Acceptance Ratio (BAR) analysis, yields a mean solvation free energy of –72 kJ mol⁻¹ for H2 in FLiBe at 1523 K, while CH4 and C2H4 remain poorly soluble (ΔGsolv < 8 kJ mol⁻¹). Accounting for these shifts lowers the overall reaction free energy to 17 kJ/mol—a 72 kJ/mol improvement—and increases the equilibrium methane conversion to ~28% from 8% at 900–1000 °C and 1 bar.
These findings indicate that solvent-mediated free-energy engineering in molten salts can overcome thermodynamic limitation in NOCM effectively. The transferable workflow i.e first-principles polarizable force-field construction and the slow growth TI method with BAR analysis validated high-temperature solvation calculations which sets the stage for rapid screening of alternative eutectic compositions. Future efforts will couple these solvent effects with heterogeneous catalysts and metal additives such as titanium. Preliminary data suggest that such additives could boost hydrogen solubility by orders of magnitude enabling more efficient carbon-free methane upgrading technologies. With a significantly lower energy demand, molten fluoride salts offer a viable thermodynamic pathway for carbon-free methane upgrading
Virtual Histopathology and Dynamic Metabolic Imaging Using Label-free Optical Microscopy for Cancer Prognostication
No full textHistology plays a crucial role in diagnosing diseases like cancer by offering surgical feedback and assessing cancer margin status and phenotype. Solid tumor cancer surgical feedback is given by fixing and staining the excised tissue, then examining the tissue with brightfield microscopy to determine if the entirety of the cancer has been removed. However, the gold standard of this method, formalin fixed paraffin embedded (FFPE) hematoxylin and eosin (H\&E) staining is a slow and tedious process, while the current, faster method, frozen section analysis, is prone to significant errors, leading to diagnosis variability. A faster, more reliable method that can image the unprocessed biopsy is desired to improve cancer patient outcomes.
Optical microscopy utilizes the various properties of tissue to measure light interactions, such as scattering, absorption, and autofluorescence emission, to produce images that identify biomolecules of interest and the tissues' structure. Light absorption is detected through a microscopy modality known as photoacoustic remote sensing (PARS). PARS detects intensity fluctuations in a back reflected interrogation light due to localized modulations in the refractive index from an increased temperature and pressure gradient due to light absorption. A separate system pathway was developed and tested to detect fluorescently labeled molecules and in later iterations, autofluorescence from tissue. PARS can utilize several light sources, 532nm and 266nm, to observe absorption in tissue for both blood and nuclei contrast using two sequential image acquisitions. A subsequent system was developed to capture PARS and fluorescence at the same time. This allowed PARS contrast validation in thick tissue using fluorescently labeled nuclei while creating the potential for a wide range of biomedical applications in both tissue and live cell imaging. Further work demonstrated a high concordance between scattered light with eosin stains. This enabled the combined use of both PARS and scattered light as a virtual H\&E stain. Large histology-like images were reconstructed in a matter of hours compared to several days when compared to the current gold standard of FFPE H\&E staining. However, to be a viable method for feedback in a surgery, the image acquisition and reconstruction process would need to take minutes, not hours.
A constant velocity stage scanner with a 1D galvanometer (GM) mirror was used to acquire long strips of the tissue and stitch them together, allowing 10mm x 10mm images to be acquired in 7 minutes. To overcome some of the limitations of this system, such as lower resolution and artifacts near the edges of the strips, voice coil scanning and a maximally realistic stain style transfer were incorporated. Using these latest improvements a new system, metabolic light absorption, scattering and emission (MetaLASE) microscopy, combines several contrasts such as cytoplasm, collagen, nuclei, nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD) to create a simultaneous virtual H\&E stain and optical redox ratio (ORR) image. The ORR is calculated by using the autofluorescence intensities of FAD divided by the sum of FAD and NAD(P)H. The ORR has been shown to be highly correlated with localized metabolism in tissue and cells. This was demonstrated in several media such as fresh tissue, FFPE thin tissue, and live cell experiments, with the ability to measure changing ORR by inhibiting metabolic processes leading to a higher ORR. This work also showed higher ORR in invasive carcinoma and areas of inflammation. MetaLASE offers key information on disease progression in cells as well as intra-operative biopsy feedback
Electrospun PEO and Gelatin Nanofiber Mats for Gene Delivery
No full textDeveloping safe, efficient, and biocompatible gene delivery systems remains a significant challenge in gene therapy. Electrospun nanofibers have gained considerable attention among emerging systems due to their high surface area, porosity, tunable morphology, and ability to mimic the extracellular matrix. In this study, polyethylene oxide (PEO) and gelatin electrospun nanofiber mats were developed and evaluated as gene delivery carriers for plasmid DNA (pDNA) and messenger RNA (mRNA). The study aimed to investigate how polymer types, complex formulations, process parameters, and electrospinning techniques affect the encapsulation efficiency, transfection, and cytocompatibility of the nanofibers. pDNA and mRNA were complexed with a commercial transfection reagent (ALL-Fect) and poly(acrylic acid) as an additive. These complexes were incorporated into PEO, gelatin, or their blend solutions and electrospun using single axial and coaxial electrospinning techniques. The morphology of nanofibers was examined to optimize the electrospinning process. Complex-loaded nanofibers were fabricated using various approaches to optimize the electrospun nanofiber parameters. Encapsulation efficiency, transfection efficiency, and cell viability of electrospun mats were evaluated. The results showed that PEO fiber mats provided superior transfection performance compared to gelatin, blend, and coaxial fibers, achieving up to 82% GFP expression (normalized to non-electrospun complexes). Single axial fibers outperformed coaxial structures, suggesting that coaxial encapsulation did not enhance nucleic acid stability. Furthermore, PEO and gelatin provided efficient nucleic acid encapsulation and enabled high gene expression levels shortly after delivery, without showing significant cytotoxic effects. However, their rapid dissolution in aqueous environments may limit long-term structural integrity and prevent prolonged release. Based on these findings, future studies can use polymers that degrade more slowly to enhance mechanical stability and better control release behavior. On the other hand, the enhancements in encapsulation efficiency and transfection performance with coaxial electrospinning were limited, since uniform and continuous fiber formation could not be achieved. Advanced electrospinning methods can also be explored to overcome these limitations for therapeutic applications
Permafrost Drilling-Waste Sump Integrity in the Sahtú Region, central Mackenzie Valley, NT, Canada.
No full textWaste-containment sites built in thaw-sensitive permafrost terrain of Northwestern Canada have shown persistent instability over the past century as their intended containment medium, permafrost, degrades under a warming climate. This thesis evaluates the integrity of five drilling-waste sumps containing contaminants in the subsurface, whether in frozen or unfrozen ground. We assess the extent to which permafrost in these drilling-sumps continues to fulfill its intended containment function. Our initial inventory of sump presence and status across the Sahtú region, NWT can be used to suggest accessible, high-priority sites for future ground-based investigations. This research contributes a foundation for sump risk assessment and emphasizes the need for expanded monitoring, collaborative management, and integration of Indigenous knowledge systems to inform future remediation and climate-resilient land-use planning in the Sahtú region. To advance our understanding of drilling-waste sump performance in discontinuous permafrost, we conducted electrical resistivity tomography (ERT) and induced polarization (IP) surveys, frost probing, shallow borehole coring, and ground temperature monitoring between 2022-2024. These methods were used to detect permafrost and/or thawed zones in sumps and map the potential mobilization of saline contaminants. Water sampling and analysis for trace metals and major ions further supported these observations. These field data were supplemented by publicly available records and regulatory reports, including those from the Mackenzie Valley Land & Water Board and the Office of the Regulator of Oil and Gas Operations. Results from five field site investigations indicate that while permafrost remains present at or near several sumps, permafrost thaw and movement of high-chargeability fluids to the surface suggest that containment integrity has been compromised in multiple sumps.
Fieldwork was completed primarily by team members of the Permafrost Archives Laboratory at the University of Alberta, and in partnership with the Sahtú Renewable Resources Board through the Petroleum Histories Project. Assessments of drilling-waste sumps in boreal regions are significantly more complex and costly than in more accessible areas, largely due to the remoteness of sites, infrastructure costs, and the vulnerability of discontinuous permafrost to disturbance. This work highlights limitations in historical documentation, regulatory data gaps, and challenges with older sumps now re-vegetated and difficult to access. Sustained funding to support further site-specific studies that can guide climate-resilient remediation planning and land-use decisions can help ensure informed, coordinated approaches to managing legacy oil and gas infrastructure in the Sahtú