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About MacSphere

MacSphere is McMaster University's Institutional Repository (IR). The purpose of an IR is to bring together all of a University's research under one umbrella, with an aim to preserve and provide access to that research. The research and scholarly output included in MacSphere has been selected and deposited by the individual university departments and centres on campus.

To contribute to McMaster's Institutional Repository, please sign on to MacSphere with your MAC ID.

If you have any questions, please contact the MacSphere Support Team.

Students wishing to deposit their PhD or Masters thesis, please follow the instructions outlined by the School of Graduate Studies.

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Recent Submissions

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    Machine Learning-Enabled Droplet Microfluidics Reveals Functional Heterogeneity in NK Cell Immunotherapy
    (2025-12-04) Ozcan, Rana; Vahedi, Fatemeh; Namakian, Shina; Ashkar, Ali; Didar, Tohid
    Natural Killer (NK) cell immunotherapy faces challenges in predicting therapeutic efficacy due to functional heterogeneity within NK populations and tumor microenvironment (TME) suppression. Here, a droplet microfluidic platform enables automated single-cell analysis of NK cell-mediated cytotoxicity against cancer cells. A machine learning-based object detection model identified target cells and death events across image sequences and generated readouts. Distinct NK cells are evaluated to quantify key metrics, including the percentage of cytotoxic NK cells, serial killing capacity, killing time per target and NK-target attachment dynamics. The results demonstrated that expanded NK cells (exNK) exhibited superior cytotoxic activity, serial killing, and rapid killing dynamics, whereas peripheral blood NK cells (pbNK), especially when they were exposed to ascites TME (pbNK-asc), displayed reduced cytotoxic abilities in all parameters. Interestingly, expanded NK cells exposed to ascites TME (exNK-asc) retained partial functionality, indicating that expansion provides resilience against suppressive factors. This single-cell analysis provides novel insights into NK-cancer cell interactions, offering a robust framework for enhancing the efficacy of future immunotherapy applications especially for optimizing off-the-shelf NK cell-based immunotherapies.
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    Meeting Package: December 2025 Graduate Council
    (2025) School of Graduate Studies
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    Approved Minutes: October 2025 Graduate Council
    (2025) School of Graduate Studies
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    MOLECULAR CATALYSIS FOR ELECTROCHEMICAL NITRATE CONVERSION TO AMMONIA
    (2026) Noor,Navid
    Electrochemical reduction of nitrate (NO3⁻) to ammonia (NH3) offers a pathway to decentralized nitrogen cycle remediation and sustainable NH3 synthesis. This thesis advances the application of molecular catalysts in electrochemical NO3⁻ reduction to NH3 by elucidating how active site coordination and the local atomic environment govern activity, selectivity, and stability. Across three manuscripts, (i) the impact of second shell coordination on metal-N4 macrocycles beyond first-shell electronics was established (ii) the active phase identity and degradation pathways of Fe- and Cu-based phthalocyanine/porphyrin catalysts under cathodic potentials were resolved, (iii) Design challenges of dual site molecular catalysts were identified using CuPc and FePc, and (IV) the impact of electronic properties and catalyst wettability on the performance of molecular catalysts in NO3- reduction using a series of functionalized FePc-R/CNTs was decoupled. Methodologically, in situ X-ray absorption spectroscopy was integrated with post-mortem microscopy/diffraction, density-functional theory, and coupled mass-transport/reaction modeling, and electrochemical evaluation was performed to identify performance descriptors in molecular catalysts. New discoveries include: (1) metal identity and second shell (porphyrin vs phthalocyanine) in molecular catalysts impacts the stability and activity (2) revealing peripheral substituents affect electronic properties and wettability and that electronic trends are frequently masked, or amplified, by local hydrophobicity, (3) a tandem Fe-Cu design paradigm, translated from molecular insights, that identify key challenges in dual site catalysts designs and key factors playing a role in obtaining synergy between the active sites. The major emphasis of the thesis is that coordination chemistry and local environment co-determine selectivity in an eight-electron nitrate reduction reaction, and that operando-validated molecular models can provide transferable rules for scalable architectures. The contributions to knowledge are actionable: design principles linking Hammett-type substituent metrics and wettability to NO3- reduction kinetics; operando criteria to validate active-phase identity; and a blueprint for dual site catalysis that bridges molecular precision with device-relevant performance.