Faculty of Graduate Studies Online Theses

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Access status: Open Access ,
MECHANISMS DRIVING KELP DETRITAL PARTICULATE ORGANIC CARBON (POC) UNCERTAINTIES AND POPULATION DYNAMICS IN THE EASTERN SHORE ISLANDS, NOVA SCOTIA
(2025-11-12) Savard-Drouin, Alexis; Not Applicable; Master of Science; Department of Oceanography; Not Applicable; Ramon Filgueira; Not Applicable; Katja Fennel; Kira Krumhansl; Anna Metaxas
Kelps are large brown algae that sustain marine life, support fisheries, and provide valuable ecosystem services. Carbon cycling is an important ecosystem service for kelp forests as they are among the most productive and widespread coastal vegetated ecosystems globally. However, current detrital carbon production estimates from kelp forests carry large uncertainties and studies rarely offer tangible solutions to improve them. We addressed this gap by quantifying population dynamics and demographic rates for the two dominant kelp species in Nova Scotia, Laminaria digitata and Saccharina latissima and estimate the detrital carbon production of both species. These estimates account for kelp size, since larger individuals produce more detritus, and for seasonal patterns, as most detrital production occurs in autumn. We found that most of the uncertainty in detrital carbon production estimates stems from variability in kelp density and population size structure. Incorporating seasonally varying erosion rates also reduces uncertainty as annual averages tend to over-simplify temporal patterns. Carbon cycling in kelp forests may be at risk as populations in Nova Scotia have undergone cycles of decline and recovery, with recent decades marked by substantial losses. While the causes of decline, warming waters, increased storm frequency, grazing by mesograzers, and invasive species, are known to affect individual kelps, their effects on population-level processes remain less understood. We constructed matrix population models to investigate the life history mechanisms driving the population dynamics of both species. We found that small individuals are critical for long-term population persistence. L. digitata depends on the year-round survival of small individuals, while S. latissima relies on autumn spore release, winter recruitment, and spring growth of small individuals. Stressors disrupting these life history events such as warming, turf algal competition, impacts from the invasive bryozoan Membranipora membranacea, and the mesograzer snail Lacuna vincta are therefore likely to drive kelp population dynamics. We also found that large individuals are essential for short-term population persistence and recovery. Both warming and M. membranacea negatively affect juvenile life histories and reduce the presence of large adults. The loss of large adults also would negatively impact detrital carbon production from kelps. These stressors are synergistic as warming promotes the population growth of M. membranacea. Together, our findings provide a mechanistic understanding for how continued ocean warming may undermine both the ecosystem functions and population resilience of kelp forests in Nova Scotia.
Access status: Embargo ,
Utilizing Metabolomics and Genomics to Enhance Parasite Resistance in Sheep
(2025-11-06) Jawad, Hamza; Not Applicable; Master of Science; Faculty of Agriculture; Received; Dr. Luiz F. Brito; No; Dr. Younes Miar; Dr. John Gilleard; Dr. Ghader Manafiazar
Gastrointestinal parasites, particularly Haemonchus contortus, significantly compromise sheep farm profitability. We integrated metabolomics and genomics data from 78 Rideau Arcott ewe lambs during controlled infection to develop diagnostic and genetic tools for parasite management. Metabolomic analysis identified candidate biomarkers—including indole acetic acid and trans-hydroxyproline—that demonstrated the potential to detect subclinical infections with progressive diagnostic accuracy. After validation, these metabolites could enable earlier diagnosis and treatment in precision livestock systems. Whole-genome sequencing revealed copy number variation patterns associated with parasite resistance and susceptibility. We identified key genes influencing immune function and disease resistance, particularly CLCA1 duplication. These findings provide practical tools for integrated parasite management: metabolite candidate biomarkers can be incorporated into field-deployable point-of-care diagnostics for on-farm detection, while genomic markers enable genomic selection for parasite resistance in breeding programs. Implementation of these diagnostic and genetic tools will help the Canadian sheep industry reduce anthelmintic dependence while improving productivity.
Access status: Embargo ,
Investigation of Gas Evolution and Safety of Materials for Lithium and Sodium-Ion Batteries
(2025-10-30) Tulloch, Meredith; Not Applicable; Master of Applied Science; Department of Process Engineering and Applied Science; Not Applicable; n/a; Not Applicable; Jeff Dahn; Alison Scott; Michael Metzger
The increased use of rechargeable batteries is one strategy in the fight against climate change, as a higher battery usage allows for the integration of more renewable energy sources. However, the development of batteries, particularly sodium-ion batteries, is still underway, with improvements to energy density and lifetime as the main research goals. Changes to the cell chemistry, the use of electrolyte additives, alloying negative electrode materials, and increasing the upper cut-off voltage to achieve higher cell capacity are all viable options to improve cell performance. This work explores electrolyte additives and Pb as a negative electrode material in sodium ion cells through on-line electrochemical mass spectrometry to investigate how these components impact the gases that are produced during battery operation. The electrolyte additives sodium difluorophosphate and 1,3,2-dioxathiolane 2,2-dioxide were studied in comparison to a control electrolyte through half cell tests and storage tests with notable differences in the gases evolved. Pb was compared to hard carbon and a blended electrode containing both materials to study the differences in carbonate and ether based electrolytes. Lastly, accelerating rate calorimetry was used to characterize the safety limits of a layered oxide positive electrode material for lithium-ion cells. Various upper cut-off voltages were used to probe the safety limitations of the material. Further investigation into the thermal response of the layered oxide positive electrode was completed using x-ray diffraction analysis. Overall, this work provides results for the gases produced from various cell chemistries in sodium-ion batteries, as well as the thermal responses seen in lithium-ion positive electrodes.
Access status: Open Access ,
Integrating Hydrologic Climate Projections into Source Water Protection Planning in Small Atlantic Canadian Communities
(2025-10-30) Dort, Amber; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; n/a; Not Applicable; Graham Gagnon; Andrew Medeiros; Lauren Somers
Climate change is a critical driver of hydrologic change in Atlantic Canada, where small utilities often manage source water with limited capacity. This research supports small communities in assessing climate change impacts on water supplies and identifies efficient modelling approaches. Lake George, the water source for Yarmouth, Nova Scotia, served as the study site. The hydrological system was characterized using public data and field observations, followed by three modelling schemes of varying complexity to simulate lake water balance. Downscaled climate projections were applied to evaluate future impacts. Lake levels were most sensitive to summer precipitation, followed by temperature and usage. Complex models with site-specific hourly data outperformed the simpler daily model, projecting more extreme impacts, including levels dropping below an outlet but not the treatment intake. While complex models provide quantitative insight, simpler models can guide qualitative assessments. Findings informed Yarmouth's Source Water Protection Plan and can guide similar communities.
Access status: Open Access ,
Africville: Reparation in the Paradoxical Legal Construction and Deconstruction of an African Canadian Community
(2001-06) Sparks, Corrine E.; Not Applicable; Master of Laws; Faculty of Law; Not Applicable; unknown; Not Applicable; Philip V. Girard; Leon E. Trakman; Jennifer K. Bankier
This thesis examines the circumstances surrounding the relocation of the community of Africville with a view to reparations for the former Africville residents. There is a discussion of the theory of reparations. From a Critical Race perspective this thesis explores the historical significance of Africville in relation to other Black Nova Scotia communities. It also explores the involvement of Blacks in relation to the early colonial settlement of Nova Scotia. From personal interviews there is a documentation of the human toll which was paid by the former Africville residents when they were relocated in 1969. These anecdotal accounts also illustrate the inequities involved with the mass relocation of an entire community. There is also a brief comparison of redress for Japanese Canadians with a view to how Japanese Canadians were successful in obtaining redress for their years of suffering as a result of mass relocation and confiscation of their property in British Columbia in the 1940's during the Second World War. In order to further contextualize the historical experience of Nova Scotian Blacks, there is an examination of how the Black community has progressed since the Africville relocation. The social advocacy which was lacking during the Africville relocation has now developed with numerous professional associations which may be able to assist Africville residents as they seek redress. There is a review of two legal claims; unjust enrichment and unconscionability. Both of these equitable claims may prove helpful during litigation for the Africville residents. These two claims are based in equity and lend themselves to judicial discretion as well as principles developed through caselaw. Equitable remedies are also examined. These legal alternatives are discussed in light of two main jurisprudential theories; Legal Realism and Critical Race Theory. This discussion reveals the importance of jurisprudential approaches in the resolution of race based litigation. Finally, there are recommendations for how the Africville aftermath can be resolved so that the Black community can begin to heal in the face of horrendous racial injustice. If these measures are implemented, race relations could be greatly improved in the province of Nova Scotia.
Access status: Open Access ,
Can Video Games Improve Adherence to Treatment in Children with Chronic Diseases?
(2009-10) Kharrazi, Hadi Hadj Karim; Not Applicable; Doctor of Philosophy; Faculty of Computer Science; Received; A. Mokashi; Not Applicable; C. Watters; P. McGrath; A. Otley; M. Shepherd
This research explored the use of interactive information technology applications for children with long term treatment regimens in which adherence is a key factor in the success of the treatment. Behavior change models play a major role in enhancing adherence to treatment in patients with chronic conditions. In this research, a conceptual framework was designed based on the Theory of Planned Behavior. The conceptual framework was mapped to game enjoyment elements to develop a game framework. The framework learned from the patient's situation based on the patient's adherence rate and measured behavioral determinants; and then the game adapted itself to the new situation and created new strategies to empower the patient in order to reinforce positive intention and behavior on the part of the patient. The game framework was tested with children in two separate user studies including IBD (Inflammatory Bowel Disease) and Type I diabetes patients. Both user studies implemented a mixed between-group and within-subject methodology. Two versions of the game were developed, one with the embedded conceptual framework and another without. Participants were assigned randomly to the treatment and control groups. The treatment group played the game with the conceptual framework and the control group played the game without the theoretical framework. In the middle of the study, each group switched to the other game type and experienced a within-subject change. The results were analyzed by GLM-ANOV A and Mix-Modeling. GLM-ANOV A showed a significant effect of game type (conceptual framework) on both behavioral intention and adherence to treatment regimens in patients with Inflammatory Bowel Disease and patients with Type I diabetes. Mix-modeling showed a significant effect of game type, time and the interaction between them on both behavioral intention and adherence to treatment regimens in both user studies.
Access status: Embargo ,
SoftAdaClip: A Smooth Clipping Strategy for Fair and Private Model Training
(2025-10-27) Soleymani, Dorsa; Not Applicable; Master of Computer Science; Faculty of Computer Science; Not Applicable; n/a; Not Applicable; Dr. Vlado Keselj; Dr. Sageev Oore; Dr. Frank Rudzicz
Differential privacy (DP) provides strong protection for sensitive data, but often reduces model performance and fairness, especially for underrepresented groups. One major reason is gradient clipping in DP-SGD, which can disproportionately suppress learning signals for minority subpopulations. Although adaptive clipping can enhance utility, it still relies on uniform hard clipping, which may restrict fairness. To address this, we introduce SoftAdaClip, a differentially private training method that replaces hard clipping with a smooth, tanh-based transformation to preserve relative gradient magnitudes while bounding sensitivity. We evaluate SoftAdaClip on various datasets, including MIMIC-III (clinical text), GOSSIS-eICU (structured healthcare), and Adult Income (tabular data). Our results show that SoftAdaClip reduces subgroup disparities by up to 87% compared to DP-SGD and up to 48% compared to Adaptive-DPSGD, and these reductions in subgroup disparities are statistically significant. These findings underscore the importance of integrating smooth transformations with adaptive mechanisms to achieve fair and private model training.
Access status: Open Access ,
Healthy Sleep for Healthy Schools: Evaluating the Usability, Effectiveness, and Implementation Potential of a School-based Sleep Education Program
(2025-08-19) Rosenberg, Lindsay; Not Applicable; Doctor of Philosophy; Department of Psychology and Neuroscience; Received; Dr. Joseph Buckhalt; Not Applicable; Dr. Gabrielle Rigney; Dr. Alissa Pencer; Dr. Penny Corkum; Dr. Penny Corkum
Adolescence is a critical time of development; however, many adolescents are not obtaining sufficient sleep, an influential factor in well-being. There are few accessible evidence-based sleep-education programs, leading to an “evidence-to-practice gap.”Schools are an optimal environment to teach sleep education, as this allows for many adolescents to learn about healthy sleep, in a place that is easily accessible to them. This dissertation evaluates the usability, effectiveness, and implementation potential of a school-based sleep education program, Healthy Sleep for Healthy Schools. A usability study (Study 1; n = 8) gathered quantitative and qualitative feedback from teachers based on Morville and Sullenger’s User Experience Honeycomb framework (2010). Quantitative feedback was neutral to positive, suggesting teachers found the program useful, useable, findable, desirable, accessible, credible, and valuable. Qualitative feedback was mostly positive, with constructive feedback regarding program length, scheduling challenges, and interactivity of student content. HS4HS was evaluated for effectiveness with students (Study 2; n = 203), using a pre/post design. The study assessed insomnia symptoms, sleep habits, daytime sleepiness, knowledge about sleep, attitudes and beliefs about sleep, and psychosocial functioning. Findings demonstrated improvements in insomnia symptoms for students with subthreshold to severe insomnia, however no improvements were made for the overall sample. Qualitative feedback on program satisfaction suggested that students learned about sleep and how to improve sleep habits, with students suggesting modifications to improve engagement, delivery time, that the program should not replace physical education, and the study measures were burdensome. The third study examined the implementation potential of the HS4HS program (Study 3; n = 12). Semi-structured interviews were conducted with teachers and school stakeholders based on the RE-AIM implementation framework (Glasgow et al.,1999), to evaluate the reach, effectiveness, adoption, implementation, and maintenance of the HS4HS program. Feedback suggested aligning with the curriculum, and fostering buy-in and engagement. This dissertation research was undertaken to better understand the program and to make modifications based on end-user data. Further effectiveness testing will be conducted upon program modification, with the goal of eventually helping to close the “evidence-to-practice” gap and thereby improve adolescent health.
Access status: Open Access ,
RETHINKING THE LEGAL ARCHITECTURAL FRAMEWORK OF THE INTERNATIONAL CLIMATE REGIME: AN EVALUATION OF THE COMPLIANCE MECHANISM WITHIN THE PARIS AGREEMENT
(2025-10-20) AMAYE, ABIMBOLA; Not Applicable; Master of Laws; Faculty of Law; Not Applicable; Professor Sara Seck; Not Applicable; Professor Robert Currie; Professor Patricia Galvao-Ferreira
The Paris Agreement is a significant change in international environmental law that prioritises three important factors: transparency, inclusion, and iterative ambition, whereas previous frameworks depended on harsh penalties and top-down enforcement. This thesis studied the Agreement’s compliance mechanism (Articles 4, 13, and 15) to determine whether a facilitative approach can be a successful international legal response to the climate catastrophe. Using a mixed-methods approach (doctrinal legal, comparative legal, and qualitative content analysis), this involved contrasting the Paris model with earlier international environmental law regimes, illustrating a transition from coercive enforcement to facilitative compliance. The results showed that three crucial elements are necessary for the Paris Agreement to be effective: transparency, reputational pressure, and iterative improvement through the use of tools like the Global Stocktake and the Enhanced Transparency Framework. Broader participation is made possible by the Paris Accord's soft law mechanisms, such as nationally specified contributions, which encourage gradual norm internalisation. Article 15's non-punitive design demonstrates political pragmatism by striking a balance between openness and ambition and ensuring almost universal participation. The research suggests that hybrid models, which combine facilitative tools with selective harder elements like graduated review mechanisms, offer the most promising way forward despite practical challenges like those associated with voluntary reporting. The Paris Agreement's Implementation and Compliance Committee's effectiveness should be further examined, with comparative studies across other international regimes potentially testing the effectiveness of hybrid compliance models.
Access status: Open Access ,
BRIDGING LEGAL GAPS AND EMPOWERING INDIGENOUS GOVERNANCE: TOWARDS A COMPREHENSIVE IMPACT ASSESSMENT OF SHIPPING FRAMEWORK FOR ARCTIC CANADA
(2025-10-21) Marie-Louise , Aren; Not Applicable; Master of Laws; Faculty of Law; Not Applicable; n/a; Not Applicable; Prof. Aldo Chircop; Prof. Patricia Galvao Ferreira; Prof. Sara L. Seck
The Arctic is undergoing rapid change due to climate change, leading to increased shipping for resource extraction. In Canada’s Arctic waters, particularly Nunavut, this rise presents serious environmental, social, and cultural risks for Inuit communities. Current impact assessment legal frameworks do not sufficiently address the unique, cumulative, and transboundary impacts of Arctic shipping, nor do they meaningfully integrate Inuit Traditional Ecological Knowledge and customary law perspectives. This research critiques Canada’s fragmented legal approach and draws lessons from Indigenous-centred, marine-focused frameworks in jurisdictions such as Greenland and other Arctic states. It calls for a unified, Indigenous rights-based impact assessment regime that meaningfully integrates Inuit governance, emphasizes marine protection, and incorporates adaptive, proactive mechanisms. Grounded in legal pluralism, environmental justice, and Indigenous self-determination, this study reimagines Arctic shipping assessments as more inclusive, coherent, and ecologically responsible processes that reflect the Arctic’s interconnected realities.
Access status: Open Access ,
OPTIMIZATION OF PROTEIN PRECIPITATION BEFORE MASS SPECTROMETRY
(2025-10-17) Dang, Ziheng; No; Master of Science; Department of Chemistry; Not Applicable; n/a; Not Applicable; Devanand Pinto; Michael Freund; Alan. A. Doucette
Efficient protein precipitation and resolubilization of the resulting pellet are critical steps in sample preparation for proteomics, directly impacting protein recovery, analytical reproducibility, and downstream mass spectrometry performance. This study systematically investigated how salt identity and precipitation conditions influence protein recovery and reconstitution in acetone-based workflows. A wide range of inorganic salts was evaluated for their effects on precipitation efficiency and compositional selectivity. Proteomic analysis revealed that different salts introduced distinct biases in the precipitated protein fraction—for example, sodium sulfate preferentially precipitated more hydrophobic proteins, while zinc salts enriched more hydrophilic ones. Key precipitation parameters were also assessed for their impact on resolubilization efficiency, including acetone concentration, salt type, drying method, centrifugation time, and mechanical handling. Higher acetone concentrations and shorter processing times enhanced protein redissolution in water. Salts containing zinc and copper significantly hindered resolubilization, likely due to metal–protein coordination, but this effect could be partially reversed by the addition of EDTA. Based on these findings, an optimized protocol was proposed to improve both precipitation yield and resolubilization efficiency. This work provides new insights into the interplay between precipitation chemistry, solvent conditions, and protein properties. The results offer practical guidelines for improving sample preparation protocols in bottom-up proteomics and emphasize the importance of optimizing both precipitation and reconstitution steps to achieve consistent and unbiased protein recovery.
Access status: Open Access ,
Quantifying northern bottlenose (Hyperoodon ampullatus) and sperm whale (Physeter macrocephalus) acoustic behavioural responses to anthropogenic noise in Baffin Bay-Davis Strait, Canada
(2025-10-17) Franklin, Kimberly; No; Master of Science; Department of Oceanography; Received; n/a; No; Dr. Sarah Fortune; Dr. Craig Brown; Dr. David Barclay
Militaries are expanding operations in the warming Arctic but aim to minimize impacts on marine mammals. To assess the effects of military sonar on northern bottlenose and sperm whales, controlled exposure experiments were conducted in Baffin Bay–Davis Strait, Canada, during fall 2022 and 2023. Acoustic data were collected using DTAGs (n = 2) and drifting hydrophone buoys (n = 8). Sonar (1.86–2.5 kHz, 1 s, max 176.4 dB re 1 µPa at 1 m), vessel (<4 kHz), echosounder (26–31 kHz), and whale sounds before, during, and after the exposures were recorded. Echolocation clicks and buzzes were analyzed relative to sonar phases and sound exposure levels. Northern bottlenose whales stopped clicking and sperm whales reduced clicking in response to sonar. Both species responded to vessel and echosounder noise and ceased buzzing (resumed >4 h afterwards). These results support the need for proactive military mitigation measures in the Arctic.
Access status: Open Access ,
Concrete Jungle: Investigating the Bioreceptivity of Biochar-Modified Concrete
(2025-10-17) Cull, Aaron; Not Applicable; Master of Architecture; School of Architecture; Not Applicable; NA; Not Applicable; Alireza Jafari; Joyce Hwang; James Forren
This thesis explores the bioreceptive implications of concrete with added biochar admixture and rough surface texture. An experiment involving four variable concrete panels illustrates the growth and retention of moss on their respective surfaces. Increased bioreceptivity was observed on two biochar-modified concrete test panels. Effective surface geometry observed in the experiment informs a pavilion design that leverages the environmental benefits of the resulting bioreceptive material.
Access status: Open Access ,
A COMPARATIVE STUDY OF THREE DRYING TECHNIQUES FOR APPLE POMACE VALORIZATION BASED ON KEY PERFORMANCE INDICATORS
(2025-10-17) Thomas, Feba; Yes; Master of Science; Faculty of Agriculture; Not Applicable; n/a; Not Applicable; Gumataw Abebe; Chijioke Emenike; Alex Martynenko
This study presents a comprehensive evaluation of three drying techniques (freeze drying, hot air drying, and electrohydrodynamic drying) for the valorization of apple pomace. The drying kinetics of each method were experimentally investigated, followed by an assessment of key performance indicators, including energy efficiency, environmental impact, economic feasibility using scaled-up 50-kilogram capacity dryers, and product quality attributes such as phenolic content, color, texture, and microbial stability. Electrohydrodynamic drying demonstrated superior energy performance, with the lowest specific energy consumption (0.34 kilowatt-hour per kilogram of water removed) and minimal carbon footprint (0.16 kilograms of carbon dioxide equivalent per kilogram of water removed). Freeze drying outperformed the other methods in quality-related parameters, including the highest phenolic content, and superior color and texture scores. However, it incurred higher energy costs and carbon emissions. Hot air drying showed the least favorable performance across most indicators, particularly in energy use and product quality. A multi-criteria decision analysis using a weighted sum model was employed to integrate all key performance indicators, resulting in FD ranking highest (aggregated score: 0.68), followed by EHD (0.65), and HAD (0.22). Additionally, an economic analysis revealed that EHD achieved the lowest annualized drying cost (approximately $32,415/year), reinforcing its economic competitiveness. These findings support EHD drying as a promising low-temperature and scalable alternative for sustainable apple pomace valorization, particularly where energy efficiency and cost-effectiveness are prioritized, while FD remains the preferred method when product quality is the primary goal.
Access status: Open Access ,
ADVANCING ECO-FRIENDLY CONCRETE: EVALUATING THE IMPACT OF WASTE GLASS POWDER AS A SUPPLEMENTARY CEMENTITIOUS MATERIAL
(2025-10-15) Choksi, Farrukh Amin; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; n/a; No; Dr. Nouman Ali; Dr. George Jarjoura; Dr. Hany El Naggar; Dr. Claver Diallo
The growing global need for concrete drives significant CO2 emissions, which motivates the partial replacement of cement with supplementary cementitious materials (SCMs). Concurrently, the disposal of waste glass presents a pressing environmental challenge due to its non-biodegradable nature and its consumption of valuable landfill space. This study evaluates waste glass powder (WGP) as a sustainable SCM in concrete. In the first experimental phase, the pozzolanic reactivity of three glass powder (GP) types: window glass (WG), bottle glass (BG), and materials-recovery-facility glass (MRF) as well as fly ash (FA) was assessed. This was done using the Strength Activity Index (SAI), a modified lime strength test, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) to quantify hydration. WG and BG achieved satisfactory SAI performance at approximately 20% replacement, while higher dosages reduced mechanical performance. The degree of hydration showed that WG and FA delayed early hydration but substantially improved hydration at a later stage. These hydration results correlated well with mechanical performance. The second experimental phase quantified the interactions of cement content, w/c ratio, and replacement level using a Taguchi approach. Each factor had three levels, and the compressive strength, workability, and sorptivity were assessed. The replacement rate had the most significant negative impact on strength, while the w/c ratio was the most influential factor for both workability and sorptivity. Based on these experimental results, predictive models using multiple linear regression (MLR) were developed and validated against test data. The alkali-silica reaction (ASR) was also evaluated for WG and BG to determine their potential for expansion. ASR expansion was reduced by more than 50% at GP replacements of 20–60% relative to controls.
Access status: Open Access ,
Developing a photo-acoustic imaging system for real-time crude oil characterization on a mobile underwater platform
(2025-10-17) Malekshahi, Ehsan; Not Applicable; Doctor of Philosophy; Department of Electrical & Computer Engineering; Not Applicable; Dr. Yahong Rosa Zheng; Not Applicable; Dr. Jose Gonzalez-Cueto; Dr. Robert Adamson; Dr. Jean-Francois Bousquet; Dr. Mae Seto
Oil spills pose severe threats to marine ecosystems and coastal economies. Detecting and characterizing oil beneath the water surface or under ice remains challenging, as existing methods such as satellite imaging, radar, sonar, and infrared sensing face limitations in resolution, reliability, or applicability under complex marine conditions. Underwater photoacoustic (PA) imaging (PAI), which leverages the strong optical absorption of oil and the deep penetration of ultrasound, has recently emerged as a promising alternative. This thesis presents the development of a compact underwater PA imager (UPAI) for real-time oil spill detection and characterization. The system integrates a nine-element hydrophone array, analog front-end electronics, and field-programmable gate array (FPGA)-based processing into a portable unit designed for deployment on autonomous platforms. By implementing time-of-arrival (TOA) detection, oil thickness estimation, and imaging directly on the embedded processor, the UPAI reduces the high-throughput data transmission requirements and power demands while enabling real-time, in-situ operation in mobile and remote environments. The contributions of this research are fourfold. First, a theoretical transfer function model for PA propagation in layered media is developed to describe signal generation and transmission. Second, a real-time imaging framework is introduced that combines robust detection of weak and saturated pulses with model-based multi-sensor imaging; using TOA measurements across hydrophones, the UPAI reconstructs oil layers without prior knowledge of laser angle or water sound speed. Third, key hardware, firmware, and software modules of an FPGA-based architecture are developed and integrated toward a complete underwater-deployable UPAI, enabling efficient real-time signal processing. Fourth, the system is experimentally evaluated in controlled aquatic conditions using an emulated PA source, demonstrating the feasibility of estimating oil layer thickness and depth. Collectively, these advances establish the foundation for a compact and deployable UPAI for underwater environmental monitoring and oil spill detection.
Access status: Open Access ,
EFFECT OF PYROLIGNEOUS ACID ON GRAPE PRODUCTION AND DISEASE MANAGEMENT
(2025-10-17) Nutsukpo, Efoo Bawa; Not Applicable; Doctor of Philosophy; Department of Plant, Food and Environmental Sciences; Not Applicable; Dr. Michael Osei Adu; Yes; Dr. Samuel K. Asiedu; Dr. Chijioke Emenike; Dr. Lord Abbey
Pyroligneous acid (PA), a by-product of biomass pyrolysis, has emerged as a promising biostimulant in agricul-ture. This thesis investigated the biostimulatory effect of PA on grape (Vitis vinifera cv. KWAD7-1) production, juice, and wine quality, and its antifungal properties. The first study focused on the effects of PA (0%, 2%, 4%, 8%, and 12%) on metabolite accumulation in grape wine. Using Nuclear Magnetic Resonance analysis, 52 me-tabolites across seven compound groups were identified and quantified. The 12% PA treatment resulted in the highest °Brix content of the grape juice and significantly (p<0.05) altered the concentrations of organic acids, amino acids, and sugars of the grape wine. The second study examined the impact of varying PA concentrations (0%, 4%, 8%, and 12%) and application frequencies (14-, 21-, and 28-day intervals) on grape growth, yield, and chemical composition. The results showed that 4% PA applied at 21-day interval significantly (p<0.05) improved grape vine growth, and yield and juice quality parameters. The treatment also enhanced the accumulation of ben-eficial compounds such as carotenoids, phenolics, and flavonoids in grape leaves, pomace, and juice. The third study investigated the efficacy of PA on Botrytis cinerea disease management in grapes. Various concentrations of PA were evaluated for their ability to suppress B. cinerea growth and infection in vivo. The results demonstrated that PA exhibited significant (p<0.05) antifungal activity against B. cinerea, with higher concentrations showing greater disease suppression. These findings demonstrate that PA application can be an effective strategy to enhance grape wine quality, productivity, and manage fungal diseases. The research provides valuable insights into the use of PA as a sustainable tool for modulating grape and wine characteristics to meet consumer preferences and po-tentially improve nutritional value, while also offering an environmentally friendly approach to disease manage-ment in viticulture.
Access status: Embargo ,
Development of a Point-of-Care Rapid Test for The Detection of Bovine Viral Diarrhea Antibodies in Bovine Blood
(2025-10-16) Morgan, Staci-Ann; Not Applicable; Master of Science; Department of Animal Sciences and Aquaculture; Not Applicable; Dr. Lisa Barrett; Not Applicable; Dr. Fraser Clark; Dr. David Barrett
Bovine viral diarrhea virus (BVDV) is a highly contagious pestivirus responsible for many production-limiting symptoms in cattle worldwide. There is no cure for BVDV, and management is highly dependent upon preventative care, immunization, and establishment of herd immunity. A point-of-care (POC) BVDV antibody detection test would allow producers to quickly and effectively determine their herd's immunity and infection status, greatly aiding BVDV management programs. Thus, this project aimed to develop a novel, accurate, and affordable rapid POC test for the detection of BVDV antibodies in bovine blood. Conjugated HRP detectors and recombinant BVDV capture antigens were utilized to develop a vertical flow immunoassay. Optimization testing was performed to determine the best conditions for detecting the target BVDV antibodies, yielding a test that could detect antibody titers as low as 1:4 in bovine plasma in under 10 minutes. A total of 195 positive and 52 negative plasma samples from both beef and dairy cattle were run on the vertical flow test (VFT) and a reference industry standard enzyme-linked immunosorbent assay (ELISA) was used to determine the test's diagnostic sensitivity (DSe) and specificity (DSp). The VFT had a DSe of 98.5% and DSp of 96.2%, while the reference ELISA had a DSe of 97.4% and a DSp of 96.2%. Comparatively both tests had substantial agreement (Cohen’s kappa = 0.91). The newly developed VFT has a diagnostic accuracy exceeding other reported rapid antibody diagnostic tests. Furthermore, the VFT’s DSe is comparable to in-lab ELISA results, suggesting that the test could be used to provide highly accurate pen-side results. The shortened performance time, ease of use, and ability of this test to be performed outside of a laboratory could greatly improve BVDV surveillance and management practices worldwide, reducing disease incidence and improving profit outcomes for beef and dairy producers alike.
Access status: Embargo ,
AUTOMATED FABRICATION OF A COLLAGEN FIBER SCAFFOLD WITH TUNABLE STRUCTURE FOR CORNEA TISSUE ENGINEERING
(2025-10-15) Albarda, Janna; Not Applicable; Master of Applied Science; School of Biomedical Engineering; Not Applicable; na; Not Applicable; Jan Rainey; Alxeander Baker; John Frampton
Several attempts have already been made to create a synthetic cornea, as this could solve the problems of graft availability and rejection for those in need of a corneal transplant. To address this need, a device was designed which has the capability of semi-autonomously creating collagen fibers. This device is capable of making a scaffold with a layer of collagen fibers structured like the corneal stroma, and a layer of structured like the corneal Bowman’s membrane. Microscopic visible light transmission studies suggest that these scaffolds transmit at least 98% of visible light. By varying the fabrication parameters, a hydrated scaffold with a tensile strength of 3.24 MPa and a Young’s modulus of 40.10 MPa was achieved. This evaluation suggests that this device can create scaffolds with mechanical properties closer to those of the native human cornea, compared to the collagen hydrogels previously used as corneal implants.
Access status: Embargo ,
Microstructural, Tribological, and Corrosion Behavior of Alumix® 123 PM Alloys: Effects of Sizing Mechanical Surface Treatment
(2025-10-16) Valizade, Nima; No; Doctor of Philosophy; Department of Mechanical Engineering; Not Applicable; Joseph Kish; Yes; Ali Nasiri; Hany El Naggar; George Jarjoura
This thesis investigates the effects of sizing mechanical surface treatment on the microstructure, wear behavior, and corrosion performance of AA2014 aluminum powder metallurgy (PM) alloys. Although sizing is a widely adopted post-sintering operation in the aluminum PM industry to improve dimensional tolerance and densification, its broader implications on functional properties remain underexplored in the existing literature. Through a comprehensive experimental approach, this work provides new insights into how varying sizing pressures influence the performance and long-term reliability of AA2014 PM alloys. Industrially sintered Alumix 123 premix powders, which are chemically equivalent to AA2014, were used in this study. A range of sizing pressures from 200 MPa to 400 MPa was applied to evaluate the effects of this surface treatment on surface morphology and height reduction. A series of characterization techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and confocal laser scanning microscopy was employed to assess microstructural evolution and pore morphology. Tribological performance was evaluated using a ball-on-disk reciprocating wear test against a steel counterface. While sizing generally improved surface hardness, the wear response exhibited a complex dependence on applied sizing pressure. Lower-pressure sizing led to localized stress concentrations around pores, promoting crack propagation and delamination. In contrast, higher-pressure sizing (400 MPa) produced a more uniform misorientation distribution and enhanced resistance to wear. Electrochemical characterization was conducted to study corrosion behavior in chloride-containing environments. Open-circuit potential monitoring, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) revealed that high-pressure sizing improved corrosion resistance, mainly through effective pore closure. However, the presence of intermetallic phases introduced by plastic deformation increased susceptibility to localized corrosion. Long-term impedance monitoring over 144 hours revealed a transition from capacitive to diffusion-controlled behavior, with the appearance of inductive loops at higher sizing pressures, indicative of elevated localized attack risk. Overall, the results demonstrate that while sizing can enhance certain performance aspects of AA2014 PM alloys such as hardness, wear resistance, and corrosion resistance, the choice of sizing pressure must be carefully optimized based on specific application requirements. This work contributes to a deeper understanding of the interplay between mechanical surface treatment, microstructural evolution, tribological response, and electrochemical behavior in aluminum PM alloys, offering valuable guidance for the optimization of post-sintering processing strategies in powder metallurgy industry.

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