Faculty of Graduate Studies Online Theses

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Using fats and combined anti-methanogenic feeding strategies to modulate the dairy microbiome and reduce enteric methane emissions
(2026-05-29) Foster, Jacob; Not Applicable; Master of Science; Department of Animal Sciences and Aquaculture; Received; Dr Anne Laarman; No; Dr Natalie Diether; Dr Rhea Lumactud; Dr Stephnanie Collins; Dr Renée Petri
As the Canadian diary industry aims to achieve net-zero emissions by 2050, anti-methanogenic feeding strategies are needed to reduce enteric methane. This research utilized two approaches to investigate how dietary strategies influence rumen microbial communities and fermentation characteristics associated with methanogenesis. Experiment one used a linseed-based product (LP) and a semi-continuous in vitro model to test increasing dietary inclusion levels of LP. Addition of LP did not reduce methane production or alter fermentation dynamics or microbial populations. Experiment two used an in vivo approach to assess the addition of cultivated red seaweed in TMR diets. Seaweed inclusion did not affect rumen pH or overall microbial diversity. However, there were differences in beta diversity and relative abundances. Likewise, methane was reduced with the addition of cultivated seaweed to TMR diet. Using both in vitro and in vivo methods provides insight into how dietary strategies can reduce emissions from the dairy industry.
Access status: Open Access ,
DESIGN AND CONSTRUCTION OF GENETIC CIRCUITS FOR ENGINEERING METHYL SELECTIVE DNA BINDING DOMAINS
(2026-05-29) Cucksey, Jordan; Not Applicable; Master of Science; Department of Biochemistry & Molecular Biology; Not Applicable; na; Not Applicable; Dr. K. Vanya Ewart; Dr. Barbara Karten; Dr. James M. Kramer; Dr. James Davey
DNA methylation is a crucial epigenetic modification that modifies protein-DNA interactions and regulates many essential processes in prokaryotes and eukaryotes. Control over DNA methylation has applications in disease characterization and treatment, memory-based genetic circuits, and cellular reprogramming. However, current approaches to studying and modifying DNA methylation lack the ability to selectively target methylated sequence-specific DNA. Furthermore, the conventional protein engineering workflow for designing DNA-binding proteins with methyl-selective, sequence-specific DNA recognition relies on inefficient multi-step screening processes. To address these limitations, a genetic circuit is proposed as a high-throughput selection platform for engineering sequence-specific, methylation-selective DNA-binding domains. The pCD plasmid was designed to present a helix-turn-helix repressor library with both methylated and unmethylated operators, and to integrate methylation-selective DNA recognition into an output that could be interrogated by GFP screening and kanamycin resistance selection. The pCD plasmid was successfully constructed using PCR-based DNA assembly of modular circuit components. Kanamycin growth results supported the use of kanamycin resistance as a selection marker to evaluate the binding specificity of engineered DNA-binding domains. The initial failure to establish circuit controls suggested the incorporation of a non-functional repressor construct, Rz. A simplified plasmid, pAD.02, was designed to further investigate the interaction between RZ and the corresponding operator, ZZ. RZ variants, XSN, XAN, XKR, and KSX were paired with TTA, TGT, GAC, and CGG operators, respectively, based on previously characterized LacI DNA-binding-domain operator interactions. These interactions were assessed across the proximal, core, and distal operator positions and revealed that the established LacI DNA-binding domain-operator pairings are not fully compatible within the RZ architecture. In total, 14 functional RZ-ZZ operator pairings were identified and can be incorporated as regulatory components in pCD. Overall, this work advances the development of a genetic circuit-based screening and selection platform for engineering methyl-selective DNA-binding proteins and suggests that surrounding structural features may influence DNA binding domain-operator interactions.
Access status: Open Access ,
Current measurements in the Drake Passage
(1972) Foster, Leslie Alexander; Not Applicable; Master of Science; Department of Oceanography; Not Applicable; unknown; Not Applicable; Dr. D. J. Lawrence; R.R. Lively; C.R. Mann
As part of the Hudson 'TO Expedition, an array of 12 current meters was moored in the Drake Passage near longitude 68° W for 10 days in February, 1970. A hydrographic section was run across the passage at the beginning and end of the mooring period. The geostrophic currents using assumed levels of no motion gave results similar to past studies. The current meter records indicated that a minimum velocity is found in the middle of the water column and they also showed the presence of a semi-diurnal tidal component. The best compromise between the current meter data and the hydrographic data is a variable level of no motion with a net transport qf 5 sverdrups toward the west, but because of lack of current meter data at the convergence zone, an unambiguous transport figure could not be determined.
Access status: Open Access ,
Suburban infill : an intervention for Gaborone's pedestrianways
(2008) Othogile, Helen Goabaone; Not Applicable; Master of Architecture; School of Architecture; Not Applicable; Jacques Rousseau; Not Applicable; Peter Sassenroth; Niall Savage
The thesis explores the potential benefits and possibilities of infill interventions within Gaborone's existing pedestrianways. The city was designed and laid out by European planners during the time of the Protectorate at the height of the Garden City movement, to become the new administrative capital for the newly independent Botswana. The resultant pedestrianways are an imported urban model that literally got "lost in translation" and as a result, the pedestrianways remain highly underutilized and could rightly be considered as wasted spaces in the city. Through a historical understanding and critical analysis, the thesis identifies why the pedestrianways are not working; how people are using them; and how the city could begin to redevelop them into meaningful and sustainable spaces.
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CHARACTERIZING BENTHIC AND PLANKTONIC CYANOBACTERIA DYNAMICS IN KEJIMKUJIK NATIONAL PARK
(2026-05-20) Macdonald, Sarah; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; n/a; Not Applicable; Dr. Daniel G. Beach; Dr. Janice Lawrence; Dr. Lauren Somers; Dr. Rob Jamieson
Kejimkujik National Park and National Historic Site contains over 46 pristine lakes and several interconnected rivers and streams, providing habitat for wildlife and recreational activities. Cyanobacteria are an increasing concern in Atlantic Canada due to their association with numerous canine mortalities. This study is the first to exclusively investigate cyanobacteria dynamics within the park. Planktonic cyanobacteria communities were assessed in 18 lakes and did not dominate microbial communities, although their occurrence followed distinct environmental thresholds. Cyanobacteria were more commonly detected in lakes with total phosphorus <12 μg/L, total organic carbon <10 mg/L, and pH levels > 5.5. Benthic cyanobacteria communities were assessed in two brooks and one lake and were a dominant component of the biofilm. Low-level anatoxins (<120 ng/g) and microcystins (<220 ng/g) were detected in biofilm samples. These findings improve our understanding of cyanobacteria communities as well as their toxin production in minimally impacted systems in Atlantic Canada.
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DEVELOPMENT AND EVALUATION OF SULFORAPHANE-RICH BROCCOLI OINTMENT FOR ATOPIC DERMATITIS MANAGEMENT IN BALB/C MICE
(2026-05-14) Chaturvedi, Chandrika; No; Master of Science; Department of Plant, Food and Environmental Sciences; Received; n/a; No; Dr. Yunfei Jiang; Dr. Carman A. Giacomantonio; Dr. H.P. Vasantha Rupasinghe
This study investigated broccoli (Brassica oleracea) as a sustainable source of bioactive phytochemicals and its potential application in atopic dermatitis (AD). Ultrasound-assisted ethanol extraction (25% ethanol, 41°C, 32 min) yielded optimal total glucosinolate content (36.6 mg sinigrin equivalence/g DW) and sulforaphane content (0.38 mg/g DW), demonstrating strong antioxidant and anti-elastase activity. In the 2,4-dinitrochlorobenzene (DNCB)-induced BALB/c mouse model, AD-like symptoms were successfully established, confirmed by elevated serum IgE and dermatitis scores. Topical application of 15% broccoli head (BH) and broccoli sprout (BS) extracts significantly reduced dermatitis scores, epidermal thickness, and serum IgE levels. The 15% BS ointment further decreased serum CCL11 levels, consistent with its approximately 17.5-fold higher sulforaphane content. Serum cytokines showed no significant changes, indicating that therapeutic effects were primarily localized within the skin. These findings support broccoli-derived extract ointments as promising natural topical agents for AD management and functional cosmeceutical development.
Access status: Open Access ,
Traduire dans le domaine des technologies transformatrices: enjeux et difficultés, théorie et méthodologie
(2026-05-12) Toukam, Dieudonné; Not Applicable; Doctor of Philosophy; Department of French; Not Applicable; Patrick Drouin; Not Applicable; Raymond Mopoho; René Tondji-Simen; Jasmina Milićević; Yannick Marchand
This doctoral thesis aims to study the specialized language of disruptive technologies (Big Data, Artificial Intelligence, and Blockchain), their terminology, and the challenges and opportunities related to English-French translation in this field. In order to familiarize linguists and translators with this specialized discourse and provide them with a reliable terminological resource, we built 5-million-word text corpus hosted by Sketch Engine, and adopted an ECL-augmented lexicosemantic approach, with the Explanatory Combinatorial Lexicology (ECL) enriching terminology by leveraging the Government Pattern for describing the syntactic cooccurrence of terms, Lexical Functions for describing the lexical relationships of terms, and a more rigorous methodology for formulating lexicographic definitions. We then created an English-French glossary (the GLOTECHT, also available online) based on our corpus and a fine-tuned methodology. Finally, we tackled translation challenges, as well as issues regarding semantic taxonomic classification, lexicographic definitions, neology, polysemy, etc.
Access status: Open Access ,
S-acylation of ATGL at Cys15: mechanism of activation and its relationship to ABHD5 coactivation
(2026-05-06) Afshari, Arezoo; Not Applicable; Master of Science; Department of Pathology; Not Applicable; Dr. Graham Dellaire; Not Applicable; Dr. Neale Ridgway; Dr. Barbara Karten; Dr. Gregory D. Fairn
Adipose triglyceride lipase (ATGL) catalyzes the first and rate-limiting step of triacylglycerol hydrolysis and is therefore a central regulator of lipid droplet catabolism in hepatocytes. Recent work identified S-acylation of ATGL at Cys15 as essential for lipase activity and lipid droplet homeostasis, but the mechanism by which this modification supports ATGL function remained unresolved. In particular, it was unknown whether Cys15 S-acylation influences ATGL activation through its major coactivator, α/β-hydrolase domain-containing protein 5 (ABHD5), and whether the requirement at Cys15 reflects a chemically specific need for cysteine modification or a more general requirement for local hydrophobicity. This thesis investigated the role of Cys15 S-acylation in ATGL activation and its relationship to ABHD5 coactivation. First, the effect of the S-acylation-deficient mutant C15S on ATGL interaction with and coactivation by ABHD5 was examined using confocal microscopy, co-immunoprecipitation, fluorescence lifetime imaging microscopy–Förster resonance energy transfer (FLIM-FRET), and cell-free lipase assays. Second, hydrophobic substitutions at Cys15 (C15F, C15L, and C15W) were tested to determine whether local hydrophobicity could partially substitute for S-acylation. Third, a preliminary microscopybased screen of candidate acyl-protein thioesterases was performed to identify potential negative regulators of ATGL deacylation. C15S retained localization to lipid droplets and co-immunoprecipitated with ABHD5, indicating that loss of S-acylation did not abolish association between the two proteins. However, FLIM-FRET showed that C15S did not exhibit the same degree of close-range proximity to ABHD5 observed for wild-type ATGL. Wild-type ATGL showed robust ABHD5-dependent activation, whereas C15S exhibited only weak stimulation, indicating that Cys15 S-acylation is required for full catalytic activation. Hydrophobic substitutions preserved lipid droplet localization and reduced lipid droplet retention relative to C15S, consistent with partial functional rescue. C15F mutant particularly restored FRETdetectable proximity to ABHD5 and partially recovered lipase activity, supporting the idea that hydrophobicity at position 15 contributes to ATGL activation, although it does not fully replace the effect of S-acylation. Finally, the thioesterase screen did not identify an obvious candidate regulator under the conditions tested. Together, these findings support a model in which Cys15 S-acylation promotes ATGL activation not by controlling lipid droplet targeting, but by enabling a productive functional relationship with ABHD5 and by contributing local hydrophobic character near the Nterminal catalytic region. This work refines the mechanistic understanding of ATGL regulation in hepatocytes and provides new insight into how defective ATGL activation may contribute to hepatic lipid accumulation and steatotic liver disease.
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DESIGN, DEVELOPMENT, AND EVALUATION OF A NOVEL HYDRAULIC SPRAY SYSTEM FOR MACHINE VISION-BASED REAL-TIME TARGET APPLICATION OF PESTICIDES ON BOOM SPRAYERS
(2026-04-30) Maambo, Humphrey; Not Applicable; Doctor of Philosophy; Faculty of Agriculture; Not Applicable; Mohamed Khelifi; Not Applicable; Travis J. Esau; Yves Leclerc; Madan Avulapati; Ahmad Al-Mallahi
A novel spraying mechanism assembly designed for machine vision–based, real time target application of pesticides on self propelled boom sprayers was developed and evaluated. The research addressed key limitations in modern precision spraying – such as nozzle valve actuation latency, boom pressure instability, and spray accuracy at higher ground speeds. The study investigates how 3D spray nozzles and a controller area network (CAN)–based feed forward pressure stabilization system can enhance timing accuracy and spraying at prescribed application rate. A comprehensive experimental investigation was conducted to characterize and optimize spray atomization parameters, including droplet size, velocity, breakup behaviour, spray coverage, and collision outcomes, across system pressures ranging from 275 to 482 kPa. Results show that 3D nozzles generate backward inclined spray patterns that effectively compensate for mechanical nozzle valve latency during real-time operation. A system pressure of 275 kPa emerged as the optimal pressure due to coarser droplets, minimized drift risk, favourable droplet coalescence, and reduced pumping power requirements. A CAN compatible feed forward pressure stabilization technique was developed to regulate boom pressure in anticipation of nozzle activation events, outperforming conventional feedback based systems by reducing pressure deviations by up to 63% and shortening pressure settling times by up to 5.7 fold. The system was prototyped on a 60 nozzle target spraying boom as an add-on system and validated through laboratory and field experiments, including tests on artificial and real Colorado potato beetle (CPB) targets. Field results demonstrated accurate real time actuation, consistent droplet placement, and practical integration of machine vision detection with hydraulic and electronic control subsystems. Overall, the research establishes an effective, scalable framework for deploying real time, target specific pesticide application technology that reduces chemical use, improves timing accuracy, and advances the feasibility of precision pest management in commercial agriculture
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Testing Implicit Safety Science Assumptions in Maritime Waterway Risk Control Options: An Empirical Analysis of PAWSA Reports
(2026-04-29) Adeli, Mehdi; Not Applicable; Master of Science; Department of Industrial Engineering; Not Applicable; n/a; Not Applicable; Dr. Jakub Montewka; Dr. Ron Pelot; Dr. Floris Goerlandt
Maritime waterway safety remains a critical concern due to the severe human, environmental, and economic consequences of shipping accidents. The Ports and Waterways Safety Assessment (PAWSA) method relies on expert judgment to propose and evaluate Risk Control Options (RCOs), including their perceived Risk Reduction Effectiveness (RRE). This thesis analyzes an empirical dataset of 50 unique RCOs extracted from 21 PAWSA reports (2016–2023) using content analysis and a tailored Strength-of-Evidence (SoE) framework. Results show substantial variation in RRE and SoE, with many RCOs lacking strong empirical support and only a small subset demonstrating both high effectiveness and strong evidence. Further analyses examine RCOs across actor groups, hierarchy of controls, and risk management phases. Findings indicate that expert judgments only partially align with common safety science assumptions. This study contributes to understanding how expert judgment reflects underlying safety concepts and supports more evidence-informed decision-making in maritime risk management.
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DRINKING WATER TREATMENT ADAPTATION FOR LEAD CORROSION CONTROL UNDER CLIMATE-DRIVEN WATER QUALITY CHANGE
(2026-04-30) Hood, Kalli; Not Applicable; Doctor of Philosophy; Department of Civil and Resource Engineering; Not Applicable; Dr. Kelsey Pieper; Yes; Dr. Heather Murphy; Dr. Amina Stoddart; Dr. Graham Gagnon
Lead in drinking water remains a public health concern worth mitigating. Drinking water treatment and distributed water chemistry are key determinants of lead release. Gradual and acute climate-driven changes in source water quality, treatment technology and regulatory targets create new challenges for corrosion control related to natural organic matter, coagulant selection, inorganic compounds, and excess product in wastewater. The goal of this work was to investigate how drinking water treatment adaptation influences lead corrosion control with an emphasis on organic matter and treatment strategies for enhanced removal, orthophosphate-based corrosion inhibitors, trade-offs with sequestration, and the feasibility of zinc-reduction. Pilot- and bench-scale studies in combination with time-series modelling and screening-level exposure projections were used to evaluate lead response to environmental events and experimental treatments. Following an extreme precipitation event, natural organic matter increased in source water and was associated with a prolonged elevation in total lead in a model distribution system and projected increases to short-term exposure risk. Enhanced organic matter removal via granular activated carbon improved lead control in a bench-scale reactor of galvanic lead solder. Equivalent total organic carbon removal was achieved at lower product doses of a chloride-based (polyaluminum chloride) coagulant relative to sulfate- based (alum), but was linked with increased galvanic lead corrosion. Orthophosphate- silicate may be an alternative to blended phosphate for systems needing to manage discolouration due to high iron/manganese, though risks of increased dissolved lead must be considered. In low-alkalinity water, reducing zinc in orthophosphate inhibitors may be feasible without compromising lead or cement corrosion, but may result in small increases in copper. These reductions could offer a more sustainable option with lower burden for wastewater treatment. This work demonstrated shifts in source water quality and treatment processes like coagulation, filtration, corrosion inhibitors and sequestrants can be protective or destabilizing for lead control and infrastructure maintenance. Utilities should consider whole-system trade-offs in lead control, treatment performance, and downstream sustainability during process adaptation or redesign.
Access status: Open Access ,
Microfluidic Systems for Long-Term and High Spatiotemporal In Situ Total Alkalinity Measurement in Marine Environments
(2026-04-30) Motahari, Shahrooz; Yes; Doctor of Philosophy; Department of Electrical & Computer Engineering; Not Applicable; Dr. Adrian M. Nightingale; Yes; Dr. Michael Freund; Dr. Ghada Koleilat; Dr. Vincent Sieben
Atmospheric carbon dioxide (CO₂) levels continue to rise, altering the global carbon cycle and driving ocean acidification. The ocean absorbs a large fraction of emitted CO₂, making accurate measurement of marine carbonate chemistry essential. Total alkalinity (TA) is a key parameter of the carbonate system because it controls seawater buffering capacity, playing a critical role in carbon uptake and air–sea CO₂ exchange. However, most TA measurements are still performed in laboratories using discrete water samples, limiting sampling frequency and spatial coverage in dynamic marine environments. This thesis presents the first field deployment of a microfluidic Lab-on-Chip (LoC) TA analyzer during an Ocean Alkalinity Enhancement trial in Halifax Harbour. The system performed closed-cell, multi-point spectrophotometric titrations in a stop-flow configuration using integrated syringe pumps, solenoid valves, and on-chip optical absorbance cells. Over 40 days, the analyzer completed 314 TA measurements and 52 onboard certified reference material (CRM) measurements, generating approximately 3,300 optical readings. This autonomous in situ platform demonstrated high-resolution monitoring of alkalinity variability that is difficult to achieve with traditional bottle sampling. To improve performance for long-term autonomous deployment, two design advancements were developed. First, a compact Dean-flow micromixer was designed and experimentally validated to enhance mixing while reducing channel length and internal volume relative to the original ~300 µL stop-flow mixer. The design was modeled using COMSOL Multiphysics and validated through bench-top TA measurements of certified reference materials. Second, the first reported droplet-based LoC TA sensor was developed. The system performs multi-point spectrophotometric titrations in segmented flow, where each droplet represents a titration point. Superhydrophobic surface modification of PMMA channels enabled stable droplet formation. This droplet architecture significantly reduces sample and reagent consumption while increasing sampling frequency, making it well suited for long-term, high-spatiotemporal-resolution carbonate monitoring in marine environments. Overall, this work demonstrates that microfluidic Lab-on-Chip systems provide an efficient and practical solution for autonomous, high spatiotemporal, total alkalinity monitoring in marine environments.
Access status: Open Access ,
Understanding Optimism: Winston Churchill and the Evolution of British Strategic Bombing Warfare Against Germany, 1914-1941
(2026-04-30) Wang, Yufan; Not Applicable; Master of Arts; Department of History; Not Applicable; na; Not Applicable; Paul Doerr; Gregory Hanlon; Denis Kozlov
This thesis examines the origins, evolution and early effectiveness of British strategic bombing warfare against Germany from 1914 to 1941. It traces the intellectual and institutional foundations of air power, from the creation of the Royal Air Force, which included the Independent Force and later Bomber Command. The treatise situates British air policy within the broader framework of interwar grand strategy, highlighting the expectations that bombers could deter enemies and deliver decisive results. Particular emphasis is placed on Winston Churchill, whose support for strategic bombing reflected both strategic calculation and personal inclination towards offensive actions. The work evaluates the limited effectiveness of strategic bombing from both British and German perspectives. Although early results fell short of expectations, British optimism and continued investment were not irrational given contemporary theorical and technological constraints. Ultimately, effective inter-service cooperation is more important than over reliance on single magic weapon in winning a war.
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CHEMICAL MODIFICATION APPROACHES IN ORGANOMETAL HALIDE PEROVSKITE MATERIALS AND SOLAR CELLS
(2026-04-30) Abdelmageed, Ghada; Yes; Doctor of Philosophy; Department of Process Engineering and Applied Science; Not Applicable; Dr Bryan Koivisto; Yes; Dr Suzanne Budge; Dr Mita Dasog; Dr Ghada Koleilat
Metal halide perovskites are promising for future photovoltaics due to their optical absorption, carrier diffusion, and tunable bandgaps. Despite efficiency gains, instability and defects remain barriers. This thesis explores chemical modifications, additive engineering, and surface passivation to improve their optoelectronic properties and stability. First, the study examined how film formation and surface chemistry affect passivation by linking deposition techniques to the results. Oleic acid was used as a hydrophobic ligand for the surface passivation of MAPbI3 films prepared by different deposition techniques. Our findings showed that the success of surface treatments depends heavily on film morphology, and that customized passivation strategies notably improve resistance to humidity and stability. Next, we explored additive engineering through sulfur-based molecular engineering with thiazoline to boost crystallization, passivate halide vacancies, and enhance interfacial charge extraction. Strong Pb–S bonds lowered trap densities, increased carrier lifetimes, and led to high-performance devices with over 22% efficiency and better stability under humid and illuminated conditions. Finally, we synergistically combined additive engineering and surface passivation techniques by using carbamide-based additives to improve crystallization and reduce defect density in the bulk and 2D capping layer, passivating surface defects. These treatments resulted in significant improvements in charge-carrier lifetimes and recombination dynamics, emphasizing the importance of controlling defect formation during film growth. Overall, this research shows that incorporating specific chemical modifications into both the bulk and interfaces of perovskite films is an effective strategy to reduce recombination losses and improve environmental stability. By elucidating the connections between molecular design, film formation, and device physics, this thesis provides a detailed framework for creating high-efficiency, durable perovskite solar cells and supporting their development toward scalable, practical use.
Access status: Open Access ,
Extreme Water Level Predictions on the Nova Scotian Coastline using a Bayesian Hierarchical Model
(2026-04-29) Sarhan, Fatma; Not Applicable; Master of Science; Department of Mathematics & Statistics - Statistics Division; Not Applicable; n/a; Not Applicable; Dr. Bruce Smith; Dr. Edward Susko; Dr. Orla Murphy; Dr. Jonathan Jalbert
The modelling of extreme coastal water levels is crucial when it comes to flood risk preparations, management, and defense design in Nova Scotia. Given the increasing frequency of flooding events in this region, it is essential to estimate their potential magnitude to mitigate their potentially devastating consequences. In extreme value analysis, return levels are quantifications of risk and represent the level that is expected to be exceeded once on average in a given time period. The challenge is that these extreme events are rare, and the data are limited and often incomplete. To address this challenge, a Bayesian hierarchical extreme value model is developed where information on extreme events is shared spatially across locations. By incorporating atmospheric covariates as physical drivers of extreme water levels, this research aims to establish a well informed Bayesian Hierarchical Model that enhances estimation precision and enables return level predictions for ungauged locations across the Nova Scotian coastline.
Access status: Open Access ,
Improving Lifetime of Lithium-Ion Cells with Electrolyte Additives
(2026-04-30) Azam, Saad; Not Applicable; Doctor of Philosophy; Department of Chemistry; Not Applicable; Betar Gallant; Not Applicable; Michael Metzger; Alex Speed; Michael Freund; Jeff Dahn
Lithium-ion batteries are the dominant technology for electric vehicles and grid energy storage, yet improvements in lifetime across wide voltage and temperature ranges remain essential for next-generation applications. Electrolyte additives improve cell lifetime by modifying the electrode–electrolyte interphases, which govern degradation processes including lithium inventory loss, transition metal dissolution, impedance growth, and electrolyte decomposition. In this work, nearly 25 novel additives and more than 100 additive combinations were evaluated in lithium-ion pouch cells containing layered oxide cathodes (LiNixMnyCozO2 or NMC) and olivine cathodes (LiFePO4 or LFP). Cells were tested under demanding conditions including high voltage operation up to 4.4 V and elevated temperatures up to 70 °C. For LFP/graphite cells cycled at 70 °C, 4% vinylene carbonate (VC) emerged as an effective additive formulation. The improved performance is attributed to residual VC in the electrolyte, which suppresses the formation of lithium alkoxide species that promote Fe dissolution from the LFP positive electrode and accelerate solid electrolyte interphase growth and lithium inventory loss. While cells containing 4% VC achieved about 1500 cycles at 70 °C, they failed at room temperature due to the formation of a highly resistive negative electrode surface impedance. To overcome this limitation, a novel additive, bis(1,3,2-dioxathiolane-2,2-dioxide) (bis-DTD), was synthesized by the author and investigated as a co-additive with lower VC concentrations. In LFP/graphite cells, the combination of 2% VC + 2% bis-DTD delivered a lifetime at 70 °C comparable to that obtained with 4% VC, while maintaining stable cycling at room temperature due to lower charge transfer resistance. This formulation enables LFP/graphite cells to operate over a wider temperature range. Bis-DTD also dramatically improved lifetime of LiNi0.65Mn0.3Co0.05O2/graphite pouch cells cycled to 4.4 V, where electrolytes containing 2% bis-DTD retained more than 80% capacity after over 2500 cycles at 40 °C and over 5000 cycles at 20 °C. In sodium-ion cells using layered oxide cathodes paired with hard carbon, bis-DTD improved capacity retention to more than 92% after about 1100 cycles at 40 °C. This single electrolyte additive has demonstrated significant lifetime improvements across diverse lithium-ion and sodium-ion chemistries, highlighting the potential of rational electrolyte additive design for next-generation energy storage systems.
Access status: Open Access ,
EXAMINING THE ROLE OF PROFESSIONAL NETWORK SIGNALS IN JOB SEEKERS BIAS AGAINST HIJAB-WEARING RECRUITERS
(2026-04-28) Sharifi, Sara; Not Applicable; Master of Science; Rowe School of Business; Received; N/A; Not Applicable; Anika Cloutier; Colin Conrad; Dana Kabat-Farr
Research on workplace discrimination shows that hijab-wearing Muslim women face disadvantages in hiring, yet is known bias toward in positions of authority. This study examined whether visible religious identity (hijab vs. no hijab) affects evaluations of recruiters and engagement with them in a professional setting. Drawing on the stereotype content model, implicit leadership theory, and selective incivility, we predicted that hijab visibility would lower competence, warmth, and leadership, and reduce engagement, willingness to connect and message tone and length. We also hypothesized mediation by attentional focus and moderation by Islamophobia. One hundred fifty-three participants completed an online experiment involving a simulated LinkedIn recruiter profile, a message-writing task, and a creativity task as a proxy for attention. Results showed no significant differences across conditions, and mediation and moderation were unsupported. However, higher creativity predicted more positive message tone. These findings suggest context shapes bias expression and highlight directions for future research.
Access status: Embargo ,
Transforming Waste Materials into Supplementary Cementitious Materials: An Approach to Mitigate the Carbon Footprint of Cementitious Composites
(2026-04-30) Jafari, Alireza; Yes; Doctor of Philosophy; Department of Civil and Resource Engineering; Not Applicable; Rahil Khoshnazar; Yes; Kyle Tousignant; George Jarjoura; Pedram Sadeghian
This doctoral research investigates the transformation of waste materials into cement alternative to reduce the carbon footprint of cementitious composites while maintaining structural and durability performance. The study focuses on recycled gypsum drywall (RGD), untreated and copper-treated biochar, and hydrochar derived from spent coffee grounds as partial replacements for ordinary Portland cement (OPC). A comprehensive experimental program was conducted at both mortar and concrete scales. More than 490 mortar specimens, with a dimension of 50×50×50 mm, and over 360 concrete cylinders, with a diameter of 100 mm and height of 200 mm, were prepared and tested to evaluate compressive strength, bulk density, ultrasonic pulse velocity (UPV), stress–strain behavior, dimensional stability, and microstructural evolution. Cement replacement levels reached up to 50% for fly ash, 30% for recycled gypsum drywall (RGD), and 15% for biochar or hydrochar. Carbonaceous materials were evaluated using both direct cement replacement and additive incorporation approaches. Engineered interface modification using copper-treated biochar was also investigated to enhance interfacial transition zone stability. Results indicate that optimized OPC-RGD–fly ash systems improved long-term compressive performance compared with OPC–RGD blends, while maintaining dimensional stability. Low biochar dosages (≤5%) exhibited filler and internal curing effects, whereas higher replacement levels introduced stiffness-sensitive behavior due to the porous and low-modulus nature of carbonaceous inclusions. Hydrochar performance was governed by interaction mechanisms with other cement alternatives, where synergistic cement alternative systems mitigated long-term deterioration. Structural-scale stress–strain analysis demonstrated that peak broadness, elastic modulus, and post-peak response were sensitive to carbonaceous inclusion content, highlighting the need for dosage optimization in structural applications. Durability was evaluated under drying, marine, and sustained 5% sodium sulfate exposure for up to 6000 hours. Measurements showed bulk density variations remained within approximately ±2.5% of baseline values, with observed transitions from pore-filling densification to stiffness-sensitive disturbance under prolonged sulfate exposure. Environmental assessment revealed that incorporating RGD and high-volume fly ash mixtures reduced carbon dioxide emissions by up to 55% relative to conventional OPC concrete. Overall, this thesis establishes a mechanistic framework for stabilizing sulfate-bearing and carbonaceous waste materials in low-carbon cementitious systems while satisfying structural performance requirements.
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Advancing eDNA Sampling for Biodiversity Monitoring
(2026-04-30) Ebanks, Tori; Not Applicable; Master of Applied Science; Department of Electrical & Computer Engineering; Not Applicable; N/A; Not Applicable; Dr. Mae Seto; Dr. Colin O'Flynn; Dr. Vincent Sieben
Environmental DNA (eDNA) is an important tool used in marine biodiversity monitoring. eDNA samplers offer a more cost effective and efficient means of the collection and concentration stages in the eDNA pipeline. A review of existing devices was done to compare their performance and features. This thesis describes the theory that determine the eDNA Sampler's effective flow rate, as well as using optics as a feedback mechanisms in eDNA sampling. The relationships between the dimensions of the fluid channel, the pressure source and flow rate were examined, and the physical limitations of flow through a membrane and filter cake buildup were also explored. This theory was supported by bench testing whose experimental results aligned with theoretical calculations. A submersible sampler was designed with this information, and was tested in the Bedford Basin in Halifax, Nova Scotia, Canada. The device captured samples at relatively high flow rates, which were successfully sequenced. The sequencing data from this instrument is presented and compared to samples captured by manual sampling and a previously tested instrument. The use of optics as a feedback mechanism during sampling was explored and showed favorable results. The results from this thesis will hopefully prove informative to the developers of eDNA samplers to refine instrument designs.
Access status: Open Access ,
SOCIO-SPATIAL EQUITY AND SOCIAL ENGAGEMENT IN SOLAR PHOTOVOLTAIC (PV) ADOPTION IN HALIFAX, NOVA SCOTIA: A MIXED METHODS STUDY
(2026-04-29) Blagogie, Lewis; Not Applicable; Master of Planning Studies; School of Planning; Received; Dr. Stanley Asah; Not Applicable; Dr. Mikiko Terashima; Dr. Chad Walker
Both globally and in Canada, inequitable access to residential solar photovoltaic (PV) systems has remained a persistent challenge to achieving a just energy transition. Yet limited empirical research has examined how a combination of economic, demographic, social, and spatial factors may interact to shape solar adoption, especially in Canada. To address this gap, I used mixed methods to investigate household solar PV adoption in Halifax, Nova Scotia. The initial quantitative phase analyzed survey data (n=158) from solar adopters to understand [in]equity and socio-spatial patterns of uptake. For example, comparisons between survey data and Halifax census-based community data revealed that solar PV adoption is skewed toward older, married, and highly educated homeowners with higher household incomes. Correlation results, however, indicate that income alone explains an extremely limited share of the variation in PV installations (p >.320), suggesting that other factors may shape adoption patterns. Follow-up interviews (n=16) designed to build on quantitative findings and shaped by the existing literature as well as a spatial analysis of survey respondents provided critical explanatory insight into these findings. Participants emphasized the importance of neighbourhood visibility (i.e., passive peer effects) and interpersonal interactions with friends and peers (i.e., active peer effects) in shaping adoption decisions. Friends frequently acted as trusted information brokers, while visible installations within neighbourhoods signaled technological legitimacy and reduced perceived risk. These findings suggest that efforts to expand solar adoption may benefit from approaches that harness community-level social dynamics.

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