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In search of novel magnetocaloric materials, a number of rare earth-based phases were designed, synthesized and investigated. These compounds were prepared by arc-melting or sintering, followed by annealing at high temperature to obtain phase-pure materials. Single crystal and powder X-ray diffraction were employed for phase identification, purity assessment, structure solution and refinement. Energy dispersive X-ray spectroscopy (EDS) was used to determine sample compositions. A Quantum Design SQUID magnetometer equipped with an alternating current (ac) transport controller (model 7100) was employed to measure magnetic data and evaluate magnetocaloric properties. The crystal structure and physical properties were analyzed via electronic structure calculations. In this thesis work, the RE5Ga3 and RECo2 (RE = rare earth) materials were chosen as a starting point for structural modifications. Specifically, substitution of Co for Ga (and vice versa) or rare earth replacement was used to design new materials. In total, four families were investigated: Ho5Ga3-xCox (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1), Er5Ga3-x(Fe/Co)x (x = 0, 0.4), RE(Co0.667Ga0.333)2 (RE = Gd, Tb, Dy, Ho, and Er), and Gd(Co1-xGax)2 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, and 1). The samples were prepared by arc-melting, wrapped in Ta foil, sealed in evacuated silica tubes and annealed at specific temperatures. The Ho5Ga3-xCox and Er5Ga3-x(Fe/Co)x systems features a Mn5Si3-type-to-Cr5B3-type structural transformation, driven by geometric factors. On the other hand, the structural transformation in the RE(Co0.667Ga0.333)2 and Gd(Co1-xGax)2 systems appears to be controlled by the valence electron count (VEC). The RE(Co0.667Ga0.333)2 (RE = Gd, Tb, Dy, Ho, and Er) phases adopt a hexagonal MgZn2-type structure (P63/mmc). Structural and magnetic properties of the MgZn2-type RE(Co0.667Ga0.333)2 materials were investigated via single crystal and powder X-ray diffraction, powder neutron diffraction (PND), and magnetic measurements. In addition to the hexagonal MgZn2-type structure, four other structures were discovered in the Gd(Co1-xGax)2 system: cubic MgCu2- (Fd3 ̅m), orthorhombic MgSrSi- (Pnma), orthorhombic CeCu2- (Imma), and hexagonal AlB2-type structure (P6/mmm). When Ga content increases, the structure moves from a “condensed cluster-based arrangement” to a “3D Network” to a “2D Network”. Meanwhile, coordination number (CN) of Co or Ga atoms changes from 6 to 4, and then to 3. Magnetic properties of many of the RE-based phases were evaluated via temperature- and field-dependent magnetization measurement. Materials exhibited a sharp ferromagnetic transition and their MCE in terms of the isothermal magnetic entropy change, was explored. / Thesis / Doctor of Philosophy (PhD)

Silicon oxide and silicon oxynitride thin films with in-situ cerium (Ce) doping were deposited using electron-cyclotron-resonance plasma enhanced chemical-vapor deposition (ECR-PECVD) on p-type silicon substrates. Oxygen was gradually substituted by nitrogen to produce SiOxNy thin films with different layer compositions. Refractive indices extracted from variable-angle spectroscopic ellipsometry (VASE) measurements classified the thin films into two main groups, SiOx and SiOxNy. The thin film composition was studied by Rutherford Backscattering Spectrometry (RBS), verifying the gradual increase in nitrogen content. Photoluminescence (PL) spectra of samples were obtained using a 375 nm laser diode as an excitation source. All samples were subjected to post-deposition annealing treatment for 1 hour at different temperatures varying from 800 to 1200 °C in both 95% N2 and 5% H2 and pure N2 gas environment, to investigate the effect of hydrogen passivation on the PL irradiance. Samples subjected to annealing yielded considerably stronger blue/white PL emission than as-deposited ones, due to the formation of Ce-containing clusters at a temperature of 1200 °C. Optimum layer composition and annealing condition to produce SiOxNy thin films with maximized Ce3+ excitation efficiency were determined. Besides, the effect of hydrogen fluoride (HF) etching on PL irradiance was studied, showing that an HF (1%) etching duration of 90 s yields the highest PL irradiance. Electrical measurements were carried out for all Ce doped samples as preliminary work for light-emitting device fabrication. ITO and Al are coated as electrodes on the front side of the thin films and backside of the substrates, respectively, using a radio frequency (RF) magnetron sputtering system. I-V measurements were performed to investigate the carrier injection properties and the dominating mechanism of carrier conduction was determined. / Thesis / Master of Applied Science (MASc)

The day that I joined McMaster University and the Department of Health Research Methods, Evidence, and Impact as a Master student, I did not foresee the amazing journey I was embarking on or the impact of my academic achievements. I was continuously challenged to think critically and apply my ideas to real world problems. Seeing the opportunity to make a difference in clinical research and patient care inspired me to begin my PhD studies. Creating knowledge and applying it practically was a difficult task, however, the opportunities to share my research in a dynamic and complex field with the world fuelled my motivation. Completing a PhD has been an incredible privilege for which I will always be grateful. To my family – Mamma, Papa, Mark and Matthew – thank you for your undying and unconditional love, support, and encouragement. A pandemic forced us to come together, and having your support 24/7 (literally) made the journey more enjoyable. To my closest friends, thank you for being a part of my life and supporting my ambitions. We all recognized my ambitiousness would set me on a difficult path and completing a PhD was not my original plan. Thank you for inspiring me to take on the challenge and ensure my work was truly impactful. Thank you for encouraging mental strength, being understanding and willing to lend a hand, reminding me that I can achieve anything I set my mind to, and inspiring me to dare. To my supervisory committee members and independent study supervisor, thank you for your continued interest in my work and for always supporting my ambitions. I am grateful for your patience and belief that I would succeed in completing what I had sought to achieve. Thank you for the chance to work together, and for your constant support and mentorship throughout my PhD journey. To the faculty, staff and fellow students at the Department of Health Research Methods, Evidence, and Impact, and the McMaster Centre for Transfusion Research, thank you for providing the resources, friendship, and guidance I needed to achieve greatness. To the panel members of the ITP Emergency Management Guideline, thank you for believing in this project and making this work possible. I look forward to implementing the results of our efforts into clinical practice. To the ITP patient community, thank you for entrusting me with the task of improving patient care and supporting me along the way. You have enabled me to be a voice for change. To the rare disease community, I know the completion of my PhD journey will not be the end of our work together. To the funding agencies who allowed this project to be possible, the Canadian Institutes of Health Research and Platelet Disorder Support Association, thank you for supporting my PhD journey and the completion of this important work. To my doctoral supervisor, Dr. Donald Arnold, it has been an honour and privilege to have learned from you and received your guidance throughout my PhD journey. Since our initial meeting, when I hobbled into the McMaster Centre for Transfusion Research offices several minutes late, I felt that your kindness and honesty would be the perfect form of mentorship to push me towards success. Thank you for recognizing my ambition and reminding me to keep focused. I will continue to apply this lesson throughout my life and strive for ‘depth’. For many years, you have been my mentor who I reached out to for advice, support, honest feedback, and encouragement. Thank you for imparting your knowledge to me over my PhD journey and teaching me how to be an inspirational mentor who highlights the strengths of their students while simultaneously supporting their growth. Although I may have finally reached the destination in my PhD journey, I know that we will continue to collaborate for many years to come. / Developing clinical practice guidelines (CPGs) for rare diseases is methodologically challenging. As each disease has so few patients, published literature includes low-quality studies or studies that do not directly address the questions of interest. As a result, CPG panelists have limited evidence on which to base their recommendations. Historically, when no evidence was available, CPGs have relied on physician opinion. This does not align with the mandate of CPGs which transparently identifies, appraises, and relies on evidence. The challenges of developing CPGs for rare diseases are exemplified by immune thrombocytopenia (ITP), a rare autoimmune disease that affects approximately 1 in 8,000 people. It predominantly affects females and young adults, and is characterized by low blood platelets that increase the risk of bleeding. Bleeding emergencies in ITP patients are critical, life-threatening events that can cause life-long morbidity and associated health care costs. Treatment of ITP bleeding emergencies requires a rapid, coordinated approach that involves emergency department staff, hematologists, pharmacy, and the laboratory. However, there is no evidence-based CPG for the management of ITP bleeding emergencies. The objectives of my PhD thesis are (1) exploring the heterogeneity of ITP diagnosis using antiplatelet autoantibodies; (2) developing a standardized definition of ITP bleeding emergencies; (3) outlining the synthesis of existing evidence on the treatment of ITP bleeding emergencies through a systematic review; and (4) developing a novel methodology to address the lack of evidence in rare disease CPGs and applying it to develop a CPG for the management of ITP bleeding emergencies. / Thesis / Candidate in Philosophy / Guidelines for rare diseases can be hard to develop because of a lack of information. Doctors and researchers make decisions on rare disease management based on their experiences, which can be limited. Low blood platelets and emergency bleeding can be caused by a rare disease called immune thrombocytopenia (ITP). When emergency bleeds occur, patients need care from the Emergency Department immediately. The problem is that there is no standard way for doctors to treat these ITP bleeding emergencies. My PhD thesis project will fill an important gap for ITP emergency treatment. First, we will assess how ITP patients are diagnosed. Second, we will define an ITP bleeding emergency. Third, we will collect existing information about ITP bleeds. Fourth, we will overcome the challenge of not having enough information by collecting new data from patient records. The method we use to develop ITP guidelines can be used for other rare diseases.

Recent studies funded by the US Department of energy have shown that coal and coal byproducts contain elevated contents of Rare Earth Elements (REEs), making them a potential resource for these critical materials. The approach employed in this research focused on the concentration and extraction of REEs from fine coal refuse derived from various preparation plants in the Appalachian coal basin of the United States. Initial efforts in this research focused on the identification and characterization of REEs in various fine coal refuse streams from nine distinct industrial preparation plants in Appalachia. The average REE content in these materials was determined to be approximately 200 ppm, but the REE content showed a strong correlation to the aluminum content, suggesting that the REEs are closely associated with the clay minerals present in the refuse. Given the relatively low REE concentrations, initial efforts sought to concentrate the REEs through decarbonization and dispersive liberation steps. In these tests, high-shear agitation in the presence of a polyelectrolyte, followed by sedimentation was able to isolate the REE-enriched fine clay particles from siliceous gangue minerals. Following the dispersive liberation step, all samples were found to have an REE content greater than 300 ppm, a benchmark used for many initial exploratory studies. In one case, the REE content was increased by more than 125%. Subsequent extraction tests initially utilized a direct ion-exchange leaching approach with ammonium sulfate as lixiviant. In all cases, the simple ion-exchange leaching process failed to recover significant quantities of rare earth elements, ultimately suggesting that the REEs in fine coal waste may be passivated or bound in a colloidal phase. To access this colloidal phase, several alternative approaches were evaluated, including leaching with alternative ion-exchange lixiviants, reductive leaching, gas-purged leaching, and others. The approach that showed the most promise was strong alkaline pretreatment, followed by ion-exchange leaching with ammonium sulfate at pH 4. A combination of strong alkali and high-temperatures treatment successfully liberated the REEs, converting them to a form amenable to ion-exchange leaching. The highest REE recovery achieved with this method was determined to be 39%. Lastly, bench-scale solvent extraction tests were used to further concentrate REEs in the leach solution and demonstrate that mixed rare earth concentrates can be successfully produced from fine coal refuse. / Master of Science / Since the introduction of personal electronics, rare earth elements (REEs) have become essential raw materials for modern life. They are used in many common household goods such as cell phones, computers, and flat screen TVs. They are also vital components in various industrial, medical, and military applications. Currently, the majority of the world's supply is obtained from China, which has raised concerns on the vulnerability of the supply chain and the potential impacts of supply disruption on clean energy technologies. In light of this risk, the US Department of Energy has classified a number of REEs as critical elements and has subsequently funded research to investigate ways to diversify the supply chain through alternative resources. The approach employed in this research seeks to extract and recover REEs from fine coal refuse. This industrial waste is a byproduct of the coal mining and beneficiation processes. Given the long legacy of coal mining in the Appalachian region, hundreds of millions of tons of fine waste are currently being stored in surface impoundments, and millions of tons of additional fine coal waste is being produced each year from active mining and beneficiation operations. By valorizing this waste material through REE recovery, mining companies will be incentivized to reprocess existing impoundments, ultimately promoting superior economic and environmental outcomes. Despite their name, rare earths are not "rare" from the standpoint of raw abundance; however, their scarcity is derived from the complexity of the extraction and separation processes. In China, the majority of the heavy rare earth elements are produced from ion-exchangeable clays. These clays have REEs weakly attached to the surface, so that they can be readily recovered by washing them with a salt solution that remove the positively charged rare earth ions from surface. The technical approach employed in this project sought to replicate this process for the clay materials found in fine coal refuse. Additional steps were needed to properly concentrate, activate, and extract the REEs; however, the end-to-end processing tests confirmed that mixed rare earth concentrates can be produced from fine coal wastes consisting primarily clay minerals.

Rare earth elements are the 14 lanthanides on the periodic table, plus yttrium and scandium. These elements play a critical role in modern-day technologies such as liquid-crystal displays, GPS systems, and fiber optic cables. A majority of the mining of these elements is from China; however, due to decreasing reserves a need for alternative processes for extracting and processing rare earth elements (REEs) is becoming increasingly important. Special focus has been placed upon the identification of REEs within coal refuse, but the phase designation and speciation is not fully understood. This investigation focuses on the characterization, speciation, and morphology of REEs within fine and coarse coal refuse. During this study, physical and chemical characterization was conducted on coal refuse samples to understand characteristics, which influence REE phase designation. Experimental methods were chosen to specifically evaluate REE content and speciation across four key characteristics: size distribution, density, seam location, and thermal decomposition. Characterization of the refuse material was conducted in two campaigns: (1) an exploratory campaign, which focused on size distribution, and physical imaging of REEs within fine refuse, and (2) a detailed campaign, which utilized sequential chemical extraction methods alongside calcination to understand the phases in which REEs are present in coarse refuse. The results show that REEs within fine coal refuse are smaller than ten microns and found with phosphorus. In general, as size decreased REE content increased, likely due to increased clay content. Further conclusion could not be drawn from simple microscopic analysis. Consequently, detailed chemical characterization was conducted to fully understand REE speciation. The tests showed that a majority of REEs within coarse refuse were within insoluble species. A calcination treatment was found to greatly increase the recovery of REEs from the metal oxide fraction, thus increasing the overall soluble species contained within the coarse refuse material. / Master of Science / Due to increasing global demand and limited reserves, alternative sources for rare earth elements (REEs) have become an increasingly important research topic. REEs are a vital component of many modern technologies, including GPS systems, fiber optic cables, and LCD screens. Current mining of REEs is primarily from Chinese reserves which are becoming increasing depleted and are not strictly regulated for environmental impact. Due to these challenges, other resources of REEs are of increasing importance. Prior research has found coal and associated byproducts to have concentrations of REEs that could be economically exploited, reducing the rate of depletion of REE resources worldwide. To develop more efficient and cost-effective processing methods, fundamental information on the mineral composition of REE-bearing materials is needed. With this information, engineers can develop better processes that can specifically target REE-containing minerals while maximizing economic and environmental outcomes. This research seeks to overcome this knowledge gap through advanced material characterization and well-controlled laboratory process testing of coal refuse. The results show that REEs typically congregate in specific material fractions (e.g. fine size, moderate density), and these materials can be readily transformed through simple heat treatment. This transformation greatly improves the processability and provides a pathway for the economic recovery of REEs from coal wastes. The further development and deployment of these technologies can have societal benefits such as: more jobs, reduced reliance on foreign sources, and environmental cleanup of current coal waste deposits.

D.Phil. (Physics) / Please refer to full text to view abstract

A transfusão de concentrado de hemácias é uma atividade que proporciona muitos benefícios aos pacientes que necessitam aumentar a capacidade de transporte de oxigênio, mas também possui riscos inerentes. A disponibilidade de unidades de concentrado de hemácias compatíveis para pacientes que são fenótipo negativos para antígenos de alta frequência e possuem os respectivos anticorpos, bem como para pacientes com uma complexa combinação de aloanticorpos contra antígenos comuns, permanece como um desafio na medicina transfusional. Painéis nacionais e internacionais de doadores e bancos de unidades de concentrados de hemácias congeladas de doadores raros têm sido estabelecidos para facilitar o fornecimento de hemácias compatíveis para esses pacientes. É previsto que, com o aumento de movimentos populacionais através do mundo e chance em potencial de desenvolvimento de anticorpos raros ou mistura de anticorpos, a necessidade da disponibilidade de doadores de sangue raro continuará no futuro. Em média, 1800 unidades de hemocomponentes de sangue raro são transportadas anualmente para serem transfundidas, podendo este número ser maior devido à dificuldade em manter registro único de todos os dados. Um banco de sangue de fenótipos raros é formado por um sistema de informações e composto pelo cadastro de dados de doadores de sangue fenotipados e genotipados e que apresentam antígenos pouco comuns na população, pelo cadastro de unidades de hemocomponentes congelados e pela possibilidade de busca de doadores compatíveis, após a inserção dos resultados de fenotipagem/genotipagem do receptor. A possibilidade de acesso rápido a um cadastro nacional com informações referentes aos doadores de sangue com fenótipo raro poderá proporcionar vários benefícios, como uma maior rapidez na localização de concentrados de hemácias compatíveis para pacientes aloimunizados e diminuição dos custos para sua triagem. Futuramente, esses dados poderão compor o cadastro mundial de doadores com fenótipos raros, o que aumentariam as chances de se localizar fenótipos compatíveis com esses pacientes. A organização de programas de fenotipagem a nível nacional e a disponibilização destes dados poderão trazer avanços significativos, tanto para reestruturação de laboratórios de imuno-hematologia como para a capacitação técnica dos profissionais que atuam nesta área. Esse cadastro poderá ser utilizado futuramente como estratégia para seleção de concentrado de hemácias a serem congeladas no país. / The transfusion of red blood cells is an activity that provides many benefits to the patients who need to increase the oxygen-carrying capacity, but also has inherent risks. The availability of RBC units compatible for patients who are negative phenotype for high frequency antigens and have their antibodies as well as for patients with a complex combination of alloantibodies against common antigens remains a challenge in transfusion medicine. National and international donor panels and banks of frozen concentrated units of rare donor red blood cells have been established to facilitate the provision of compatible erythrocytes in these patients. It is expected that with the increase of population movements across the globe and likely potential development of rare antibodies or antibody mixture, the need for the availability of rare blood donors will continue in the future. On average, 1800 units of rare blood components are transported annually to be transfused, this number may be higher because of the difficulty in maintaining single record of all data. A rare phenotypes blood bank consists of an information system and consists of the registration of blood donors phenotyped and genotyped data who presenting unusual antigens in the population, the register of frozen blood products units and the possibility of seeking donors compatible, after insertion of the results of phenotyping / genotyping receiver. The possibility of quick access to a national database with information pertaining to blood donors with rare phenotype can provide several benefits, such as greater speed in locating concentrates compatible red blood cells to alloimmunized patients and lower costs for their screening. In the future, these data may select global register of donors with rare phenotypes, which would increase the chances of finding phenotypes consistent with these patients. The organization of phenotyping programs at national level and the availability of these data can bring significant advances for both restructuring immuno-hematology laboratories as for the technical training of professionals working in this area. This register could be used as future strategy for red blood cell selection to freeze in the country.