QSpace

Queen's Scholarship & Digital Collections

QSpace is an open access repository for scholarship and research produced at Queen's University. QSpace offers faculty, students, staff, and researchers a free and secure home to preserve and present their scholarship.

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Digital Collections 5940
This community includes digital collections produced by members of the Queen’s community, as well as digital special collections made available via W.D. Jordan Rare Books & Special Collections.
Exams & Syllabi 0
This community provides access for staff and students at Queen’s University to degree examination papers and syllabi. To access Exams & Syllabi off campus please login using your Queen's NetID and password.
Graduate Theses, Dissertations and Projects 10213
This community includes graduate theses, dissertations and projects produced by students at Queen’s University.
McGill-Queen's University Press 9
Scholarly Contributions 14539
This community includes Queen’s peer-reviewed research publications, including journal articles, book chapters, conference proceedings, and more.

Recent Submissions

Access status: Open Access ,
THE EFFECT OF CARBON DIOXIDE ON THE FLOTATION OF PYRRHOTITE AND PENTLANDITE AT EAGLE MINE
Kolter Weaver; Mining Engineering; Gibson, Charlotte
Eagle Mine is a nickel-copper mining and milling operation located in Champion, Michigan. The mine is evaluating options to improve project economics through increasing nickel recovery and/or producing a desulfurized tailing through pyrrhotite flotation, which could be used as mine backfill. As part of this evaluation, the objective of this study was to increase pentlandite and pyrrhotite recovery during flotation, using CO2 and other reagents as flotation activators. Flotation testing was conducted on two process streams from Eagle Mine: (1) Bulk Rougher Tailings (BRT), and (2) Bulk Rougher Feed (BRF). Testing showed that CO2 and copper sulfate additions were effective when floating BRT, where up to 90% pyrrhotite and 36% nickel recoveries were achieved. In the flotation of the BRF, CO2 addition resulted in a 2.7% increase in nickel recovery compared with baseline plant conditions, driven by a large increase in pyrrhotite recovery. In addition, CO2 was tested on two different BRF ore types (SMSU and KEEL) in conjunction with different types of grinding media (mild steel (MS) and high chrome (HiCr)). Grinding SMSU ore with MS media while adding CO2 during flotation resulted in a 6.4% increase in nickel recovery. When grinding SMSU with HiCr media and while adding CO2 during flotation, the nickel recovery increased by 4.7%. For the flotation of the KEEL ore using CO2, there was a 9.6% increase in nickel recovery after grinding with MS and a 6.6% increase in nickel recovery after grinding with HiCr. It was postulated that the CO2 addition altered the zeta potential of pyrrhotite, leading to higher recovery. Subsequent galvanic interaction testing showed mild steel-pyrrhotite had larger galvanic interactions relative to high chrome-pyrrhotite at pH 6 (in the presence of CO2), while high chrome-pyrrhotite had stronger galvanic interactions at pH 9 (no CO2). These results suggest that at low pH in the presence of CO2, iron hydroxide formation (oxidation) was limited due to iron carbonate formation and elemental sulfur remained, promoting xanthate attachment and improving flotation kinetics. The findings of this thesis demonstrate the benefits of carbon dioxide in the processing of Eagle Mine ores, improving nickel recovery and assisting with the desulfurization of tailings.
Access status: Open Access ,
Polyphosphate Modification of Human Proteins and a New Mechanism for Regulating Super-Enhancer Activity
Yang, Zhiyun; Biomedical and Molecular Sciences; Jia, Zongchao
Inorganic polyphosphate (polyP) is an evolutionarily conserved linear polymer of orthophosphate that plays diverse regulatory roles across biological systems. Recent work has implicated that polyP modulates protein function through post-translational modification (PTM), which has gained increasing scientific interest. However, its human protein interactome and molecular functions especially its role in gene regulation in human cells remain poorly defined. This thesis demonstrated that polyP serves as a multifaceted regulatory molecule in human cellular biology, identified many human proteins containing lysine-rich regions as polyP targets and uncovered polyP’s role in manipulating super-enhancer complex to regulate gene expression. Through a comprehensive screen of 57 lysine-rich human proteins, selected via mass spectrometry and bioinformatic analyses, this study identified 41 proteins that undergo denaturation-resistant polyP modification. Through mutagenesis and binding assays, this study established that intrinsically disordered lysine-rich motifs are essential for polyP modification, with consecutive lysine residues as critical determinants. Functional assays further revealed that polyP binding modulated the activity of diverse regulatory proteins - it inhibited phase separation of the transcriptional regulator NKAP, suppressed GTPase activation of the oncogenic driver KRAS, and reduced the helicase activity of DDX55. Building on this framework, this study also identified a previously unrecognized role for polyP in transcriptional regulation through its direct interaction with components of the mammalian super-enhancer complex. PolyP modified the Mediator subunit MED1, the coactivator BRD4, and the transcription factor YY1. These modifications disrupted their capacity for phase separation, reduced MED1 and BRD4 expression and impaired YY1 nuclear localization. In addition, polyP inhibited YY1 dimer formation and disrupted YY1-mediated DNA looping, ultimately attenuating super-enhancer driven transcription. Collectively, this thesis provides a comprehensive resource for polyP studies and unveils a novel gene regulation role of polyP, exploring the physiological and pathological significance of polyP while establishing it as an important player to epigenetic regulation, cellular homeostasis, and human disease.
Access status: Open Access ,
Cuban-Canadian Relations: an Analysis of Economic Ties, Canadian Entreprenuers, and Academic Exchanges
Brady Reid; History; Dubinsky, Karen
Canada and Cuba have maintained diplomatic ties since 1945 despite having vastly different political systems. Although diplomatic relations between the two countries have existed for over eight decades, Cuban studies in Canada remains an emerging field. This thesis seeks to add a historical analysis of Canadian-Cuban relations, focusing on economic relations, Canadian entrepreneurship, and educational ties between Canadian and Cuban post-secondary institutions. The majority of the research focuses on Canadian-Cuban exchanges during Cuba’s Special Period, the largest economic crisis in Cuban history. Following the collapse of the Soviet Union, Cuba lost its largest trading partner and access to Soviet instructors who helped maintain Cuba’s education system. Canada’s renewed interest in Cuba during the Special Period and Cuba’s new willingness to open its economy to foreign investment created a niche business opportunity for Canadian entrepreneurs, given the absence of competition from American corporations. At the same time, Canadian entrepreneurs were travelling to Cuba in search of trade opportunities, Canadian academics began travelling to Cuba to help provide the expertise needed for Cuba’s dramatic restructuring.
Access status: Embargo ,
ASSESSMENT OF CONTAMINANTS IN ENVIRONMENTAL SAMPLES AND FOOD SOURCES USING INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND X-RAY ABSORPTION SPECTROSCOPY
Helen Lord; Chemistry; Beauchemin, Diane; Koch, Iris
Environmental chemistry is advanced through the application of high-performance liquid chromatography (HPLC), inductively coupled plasma mass spectrometry (ICPMS), and X-ray absorption spectroscopy (XAS) to investigate the bioaccessibility and speciation of trace elements (TEs) in environmental samples. This work examines Pb, Cd, Zn, Se, and As in edible seaweed, alongside As speciation in peatlands, with the goal of assessing human health risks and understanding As behaviour in peatlands. A seaweed certified reference material (GSEA-1), derived from Ascophyllum nodosum and commercially available as food, was used to evaluate the bioaccessibility of Pb, Cd, Zn, and Se under simulated gastrointestinal conditions. A continuous on-line leaching method (COLM) coupled with ICPMS was compared to a modified batch extraction. Both approaches indicated low bioaccessibility, with COLM showing less than 25% across digestion phases. Risk assessment suggested negligible concern for Zn and Se, but potential exposure risks for Pb and Cd under high-consumption scenarios. Inorganic and organic As species, including monomethylarsinic acid and dimethylarsinic acid, were identified using HPLC-ICPMS in the same seaweed. Exposure modeling based on consumption of 100 g twice weekly indicated that bioaccessible inorganic As concentrations (2.85 ± 0.19 mg kg⁻¹) may pose both carcinogenic and non-carcinogenic risks. Organic As species (19.9 ± 1.5 mg kg⁻¹) were also present at levels contributing to non-carcinogenic risk, highlighting the importance of speciation in food safety assessments. Complementary studies of As cycling in five Canadian peat bogs using HPLC-ICPMS and synchrotron-based XAS showed that inorganic As and As–S species predominated, with limited occurrence of organoarsenicals such as trimethylarsine oxide. Total As concentrations amongst the five bogs range from 0.57 – 680 mg kg-1. Two peat bogs are within the range of reported concentrations from two Albertan peat bogs (0.24–1.58 mg kg⁻¹). Elevated levels in Yellowknife likely reflect natural arsenopyrite and mining-related contamination, while some samples from Sifton Bog exceeded background levels by 20–50 times, suggesting urban contamination. Overall, this research demonstrates the value of advanced analytical techniques for understanding TE behavior, improving environmental risk assessments, and supporting the safe use of alternative food sources while enhancing contaminant monitoring in environmental systems.
Access status: Embargo ,
Key Components for Delivery of Collaborative Mental Health Services in Rural Ontario Primary Care Settings: An Exploratory Study
(2026-05-06) Landry, Terrence Edward Donovan ; Rehabilitation and Health Leadership; Ghahari, Setareh
Background: Mental illness is a health concern in Canada, with mental health-related visits accounting for approximately 20% of visits with family physicians in Ontario. In rural areas, collaboration between primary care and mental health services are often fragmented. Although collaboration among primary care providers and mental health clinicians is critical to delivering recovery-oriented care, such collaboration remains inconsistent, particularly in rural areas. Objective: This research aimed to answer the following: From the perspective of mental health collaborators, what are the key components required to enhance recovery-focused, collaborative mental health services for adults living in rural Ontario who experience mental illness? Methods: Using semi-structured interviews, we sought the perspectives of people with lived experience, their families, and healthcare providers to understand their roles as collaborators in the healthcare system. We used reflexive thematic analysis method (Braun & Clarke, 2022) to extract themes. Results: Nineteen participants were interviewed, including people with lived experience (n=8), family members of people with lived experience (n=4), primary care providers (n=3), and specialty mental health clinicians (n=4). Three themes were generated: 1) We all recognize that medication is only a small piece of the puzzle; 2) I put in a referral for mental health, and I don’t hear back, and 3) The services are pretty good considering where we live. Conclusion: The study's findings underscore the need to strengthen collaboration between primary care and mental health providers. In rural areas, especially, supporting a recovery-oriented approach requires more effective partnerships and reliable communication processes, such as mental health rounds, to ensure coordinated care. System design requires individuals with lived experience and their family members to be engaged. To deliver recovery-oriented care, mental health clinicians and primary care providers benefit from developing competency in understanding the broader healthcare system, appreciating the role of primary care, and fostering effective collaboration. Knowledge Translation: This knowledge translation will include submitting to scholarly journals and presenting it at academic conferences. Findings will be shared with leadership at Providence Care.