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Pairing Synchrotron Radiation with an ATR-Integrated Microreactor for In-Situ Spatiotemporal Characterization of Chemical Reactions
No full textMicrofluidic devices consist of microfabricated structures designed to control minuscule
volumes of fluid with exceptional precision. The growth of this field has allowed researchers
to miniaturize lab-based processes, providing an alternative experimental approach
which is more efficient, safer, eco-friendly, and cost-effective. In-situ monitoring
of chemical reactions is greatly important to the field of chemistry. Real-time characterization
allows for a better understanding of the system by investigating the underlying
mechanisms and reaction kinetics. Fourier-transformed infrared (FTIR) spectroscopy is a
suitable technique to be coupled with microfluidics as it is non-invasive, straightforward,
reliable, and sensitive to molecular changes which occur during a reaction. With the use of
attenuated total reflection (ATR) FTIR spectroscopy, significant attenuation of radiation
by the fluidic environment is overcome. The quantitative capabilities of IR spectroscopy
coupled with a microfluidic device provide researchers with the ability to monitor reaction
variables such as reagent concentrations in-situ.
In this thesis, I evaluate the abilities of a unique microfluidic device equipped with
a single-bounce ATR element by monitoring a proof-of-concept chemical reaction using
synchrotron sourced IR radiation. The unique capabilities of the Mid-IR beamlines’ horizontal
ATR (hATR) endstation at the Canadian Light Source (CLS) allow the beam spot
to be positioned at any point along the length of the channel to assess the chemical environment
at many different reaction times. Coupling the endstation capabilities with the
single-bounce ATR accessory and synchrotron radiation allows different sensing areas to
be individually addressed, thereby providing the ability to obtain spatially and temporally
resolved information. This microreactor provided in-situ characterization, which was used
to spatially and temporally track the concentration changes throughout an SN2 reaction.
The collected measurements were then used to determine the kinetic rate constant of the
monitored reaction. Therefore, this thesis successfully demonstrates the microreactors’
impressive capabilities to monitor a reaction and extract kinetic parameters
Toxicity of surface water and pore water from an oil sands pit lake (Lake Miwasin) to Daphnia
No full textCanada holds approximately one-third of the world's confirmed crude oil reserves, primarily concentrated in the Alberta Oil Sands (AOS) region, in the form of bitumen. However, the extraction process of oil sands generates significant volumes of tailings and process water, which raises concerns about their potential effects on aquatic life and the need for remediation. Lake Miwasin, constructed in 2018, serves as a pilot-scale pit lake and a model for this context. It features treated fluid tailings overlaid by a mixture of oil sands process-affected water (OSPW) and freshwater, exhibiting seasonal stratification. Since its establishment, Lake Miwasin has been colonized by various organisms, including the Crustacean, Daphnia pulex. Monitoring data from Lake Miwasin has shown the presence of compounds in both water and sediment that could be detrimental to aquatic organisms. Therefore, the primary goals of this research were to assess surface water and pore water toxicity, including an evaluation of selenium (Se) bioaccumulation in Daphnia species exposed to the conditions representative of Lake Miwasin at its early development stages and possibly other future pit lakes in the AOS region.
This study examined the toxicity of Lake Miwasin surface water (LMW) and pore water (LMP) using lab-cultured and native Daphnia species. Interestingly, LMW exhibited no acute or chronic toxicity towards D. magna and D. pulex (lab strains) and the native Daphnia sp. (collected from Humboldt Lake, SK, Canada). However, LMP demonstrated acute toxicity to both lab strains and the native D. pulex (collected from Lake Miwasin, AB, Canada). Lake Miwasin pore water also negatively impacted lab D. pulex reproduction, leading to a reduced number of offspring. Salinity emerged as a significant stressor in LMP, and a Toxicity Identification Evaluation (TIE) phase I suggested ammonia and metals in LMP as potential contributors to the observed toxicity in the tested organisms. On a related point, results showed that concentrations of dissolved Se in LMW from 2019 to 2021 exceeded the Canadian Council of Ministers of Environment (CCME) water quality guidelines for long-term aquatic life protection (1 µg/L), and the British Columbia Ministry of Environment (BC MoE) water guideline alert concentration for the protection of aquatic life (1 µg/L). The latter water guideline was also adopted by the Government of Alberta. Further, another experiment assessed Se bioaccumulation in D. pulex through dissolved and dietary exposure routes, drawing comparisons to native specimens collected from Lake Miwasin. In semi-static tests (12 days), lab strain D. pulex exposed to selenate [Se(VI)] showed a Se concentration-dependent increase from days 5 to 12 for most treatments, whereas a lower bioaccumulation occurred at higher Se concentrations, which suggests a potentially internal regulatory mechanism. Native D. pulex exposed to LMW in laboratory conditions showed that Se bioaccumulation levels were similar to those of D. pulex collected directly from Lake Miwasin. Despite these findings, the Se concentrations in D. pulex from both lab exposures and Lake Miwasin collections remained below available regulatory guidelines for invertebrate tissue (4 µg/g), suggesting that D. pulex appears to pose minimal risk as a food source in the Lake Miwasin ecosystem.
These findings provide useful insights into the toxicity of Lake Miwasin water to aquatic invertebrates, the potential for Se bioaccumulation in daphnids in Lake Miwasin, the potential enhancement of pit lake monitoring programs, and the decision-making regarding the use of end pit lakes in the reclamation of OSPW and oil sands tailings
Morphological, Histological, And Developmental Features Of Perichondral Bone In Skates And Sharks Suggest That Modern Cartilaginous Fishes Make Bone
No full textBone is a mineralized (or calcified) tissue type and a defining feature of the vertebrate skeleton. Ancestral vertebrates made bone and most modern vertebrates including bony fishes and tetrapods retain bone. However, bone has never been characterized in modern chondrichthyans (sharks, skates, rays, and chimaeras), and modern chondrichthyans are hypothesized to have lost the ability to make bone during their evolution. Previous studies show that sharks have mineralized tissues with some morphological and histological features that are consistent with vertebrate perichondral bone. These mineralized tissues in sharks have been described as bone-like and occur in neural arches and a specific histological region (i.e., cap zone) of discretely mineralized tesserae. While these observations in sharks challenge the hypothesis that modern chondrichthyans lack bone, it remains debated whether other modern chondrichthyans like skates and chimaeras have bone-like tissues. Because bone-like tissues have been characterized mostly in adult sharks, it is not known whether important developmental features of perichondral bone such as cartilage maturation is demonstrated by bone-like tissues. Besides bone-like tissues, chondrichthyans also display a unique areolar mineralized tissue in the vertebral body (centrum). These chondrichthyan mineralized tissues display distinct mineralization patterns such as a classic polygonal pattern of tesserae, a compact bone-like pattern of neural arches, and a compact pattern of areolar mineralized tissue. These chondrichthyan mineralization patterns have been described in sharks and skates, but relevant data from chimaeras needed to assess whether all groups of modern chondrichthyans demonstrate these morphological features are lacking. This thesis addresses these and other knowledge gaps in the skeletal biology of modern chondrichthyans by testing the hypothesis that bone-like tissues are shared by modern chondrichthyans and are homologous to perichondral bone in other modern vertebrates. Comparative morphology and embryology were the two main approaches adopted to test this hypothesis. Specifically, mineralized tissues in two skate species (the little skate Leucoraja erinacea and the Eaton’s skate Bathyraja eatonii), a shark (the catshark Scyliorhinus canicular), and a chimaera (the spotted ratfish Hydrolagus colliei) were characterized using desktop and synchrotron micro-CT imaging, histological, histochemical, and immunofluorescence assays. Micro-CT renderings showed a bone-like mineralization pattern in neural arches of the skates and the shark, but this was absent in neural arches of the spotted ratfish. Micro-CT renderings and histological analyses of tesserae showed that the bone-like cap zone was present only in the skates, and the polygonal tesseral mineralization pattern was associated with large and laterally extensive bone-like cap zones. Another mineralization pattern described herein as trabecular tesseral was characterized in several endoskeletal regions of the skates, the catshark, and the spotted ratfish. The trabecular tesseral pattern was morphologically distinct from the polygonal tesseral pattern which is classically associated with the chondrichthyan endoskeleton. Micro-CT renderings and histological data also showed that areolar mineralized tissue, which has been described in only sharks and skates, was also present in the spotted ratfish. Perichondral bone formation in other modern vertebrates is driven by cartilage maturation. Developmental data from the little skate showed that the main histological features of cartilage maturation, such as chondrocyte hypertrophy and initiation of matrix mineralization by hypertrophic chondrocytes, were associated with the development of bone-like tissue in neural arches. In addition to limited reports of bone-like tissues in sharks, data in this thesis showed that other modern chondrichthyans like skates have bone-like tissues. Developmental features of perichondral bone demonstrated by neural arch bone-like tissue suggest that bone-like tissues and perichondral bone are homologous
Infrared Chemical Imaging of Custom-Made Microfluidic Devices
No full textMicrofluidic devices are designed to streamline and improve the operation of chemical processes in a wide variety of industries. Miniaturization has a vast number of advantages; most notably, the large surface area to volume ratio which allow for enhanced control over the physical properties within devices. Such precision leads to more efficient reactions and higher quality products making on-chip chemical synthesis desirable. Optimization of device performance requires an in-depth analysis of the flow profiles, requiring in-situ characterization techniques. Infrared (IR) imaging integrated within microfluidic devices is a label-free, non-invasive detection strategy which provides an in-situ probe to visualize flow patterns and can be utilized to identify and quantify molecules on-chip. IR light is quickly attenuated by optically dense matter such as solvents and device materials when samples are probed in transmission or reflectance modes. In attenuated total reflection (ATR) mode, IR light is directed through a high refractive index material such as a Si internal reflective element (IRE) interrogating the sample-IRE interface with an evanescent wave, limited to within one micron of the surface in the wavelengths of interest. Such a localized probe depth allows for design freedom in both the channel depth and materials. Within a microfluidic device, this imaging technique probes the solution near the no-slip boundary; fluid near channel extremes is flowing at a much slower rate than the bulk due to resistance of the solution with the walls of the channels. As a comparison of the experimental results with the physical phenomena within the devices is crucial to justify the technique, flow profiles must be modelled with both commercial software and mathematical predictions.
This thesis aims to develop and demonstrate the focal plane array (FPA) imaging capabilities of the horizontal ATR microscope at the Mid-IR beamline of the Canadian Light Source by imaging fluid flow in custom-made microfluidic devices. Resulting images are compared to expected flow profiles generated by simulations. This work is highly motivated by a desire to implement synchrotron IR imaging using this endstation and offers a prerequisite study for larger field-of-view optimization with a globar source before the extension to synchrotron light, with lower noise and smaller spatial resolution, may be realized
INFLUENCE OF MICROBIAL SULFATE REDUCTION ON PORE-WATER CHEMISTRY IN OIL SANDS FROTH TREATMENT TAILINGS
No full textOxidative weathering of froth treatment tailings (FTT) at oil sands mines in Northern Alberta has the potential to generate acidic and metalliferous porewater. Residual bitumen and light hydrocarbons in FTT support growth of a diverse range of microbes, including those capable of dissimilatory sulfate reduction (DSR). This biogeochemical process can be effective in removing sulfide-mineral oxidation products such as Fe, SO4, and trace elements including As, Co, Cu, Ni, Se, and Zn through sulfate reduction and sulfide mineral precipitation under anoxic conditions. While previous experiments that have stimulated sulfidogenesis through organic carbon amendments effectively decreased the mass flux of sulfide-mineral oxidation products in mining environments, the extent of this process and its ability to attenuate sulfide-mineral oxidation products in FTT supported by residual hydrocarbons is unknown. The objective of this thesis is to assess the impact of microbial sulfate reduction on FTT pore-water geochemistry and to determine the potential extent to which this process may be supported by residual hydrocarbons within the tailings deposit. Laboratory experiments were designed to examine the influence of sulfidogenesis on pore-water chemistry and to constrain rates of sulfate reduction, while assessing the capacity for metal(loid) removal due to this process. Through batch and column experiments sulfate reduction was found to contribute to metal(loid) and sulfate removal, as well as pH buffering and H2S generation. Removal of As, Co, Ni, and Se exceeded 90% in simulated porewater over a pH range of 5 – 8. Removal of Fe was minimal below pH 7, but exceeded 95% in solutions above pH 7 with long residence times. Zn removal was influenced by ∑S(-II)(aq) concentrations, with increased Zn removal seen at lower ∑S(-II)(aq) concentrations. Sulfur isotope samples taken during the batch experiment show an increase in 34S-SO4 with decreasing SO4(aq) concentrations over time, showing ongoing microbial sulfate reduction during the experiment. A mass-based approach to determine sulfate removal found sulfur removal rates remained constant around 1.5 μmol d-1 g-1 when solutions were not saturated with respect to gypsum. Residence time and pH were major influences on the effectiveness of sulfate reduction, with enhanced metal(loid) removal occurring with longer residence times at circumneutral pH. These results show the pool of organic carbon in FTT deposits is capable of supporting dissimilatory sulfate reduction and this process can decrease mass fluxes of sulfide-mineral oxidation products in FTT porewater
Female Chief Executive Officers and Cross-Border Mergers and Acquisitions
No full textThe surge in Cross-Border Mergers & Acquisitions (CBMAs) has paralleled the advancements in
global technology, providing opportunities for seamless information exchange. As the landscape
of Chief Executive Officers (CEOs) evolves, literature has taken further interest in CEO gender.
Drawing upon data from WRDS Compustat, Execucomp, and SDC Thomson Platinum spanning
thirty-one years, our study analyzes the relationship between United States CEOs and CBMAs.
The objective of our research is to discover the relationship between CEO gender on CBMA
interactions. Employing a comprehensive set of CEO, firm, and deal-level controls, we present
significant findings. Our analyses indicate female CEOs are less likely to engage in CBMAs, while
using more stock as a method of payment, aligning with financial and behavioral literature of
female CEOs being inherently more risk averse. Our results display there is no statistically
significant relationships between female CEOs, acquisition premium, and deal size. This study
provides further analyses on the unique decision-making tendencies of CEOs based on gender and
gender behaviors, providing valuable results on the patterns influencing their decisions and
consequences
CELL MORPHOLOGY-BASED CHARACTERIZATION OF THE IRREVERSIBLE ELECTROPORATION FOR TUMOR ABLATION
No full textIrreversible Electroporation (IRE) stands at the forefront of contemporary tumor ablation research. An in-depth understanding of how cells with different morphologies respond to various IRE protocols is crucial for assessing their vulnerability to such ever-changing cancer treatment. In short, this relationship is called throughout this thesis.
This thesis study was motivated to explore this relationship based on an in vitro IRE experiment of single cells. The results of the study affirmed the influence of cell morphological features on its susceptibility to IRE treatment. The simulations in the study spotlighted how distinct morphological features impact the distribution of transmembrane potential (TMP) over a threshold value on the plasma membrane. The experimental data in the study, shifting from in silico to in vitro, highlighted disparities in lethal areas for different tumor cells under identical IRE protocols. The study also correlated the membrane occupancy of where TMP over a specific threshold value with the lethal area from in vitro IRE experiments, to improve our understanding of the vulnerability of cells in the context of IRE as well as the pivotal role of their morphology. This study developed a quantitative expression of this relationship, which was also called single cell electroporation (SCE) model, because the relationship also contains the information of cell lethal to IRE. Therefore, the SCE model is useful to guide the IRE operation in the clinical setting, especially promoting the current thinking in medicine, i.e., personalised medicine.
This thesis has made a few scientific contributions: (1) Provision of a method along with its tool to automate the extraction of cell morphology along with features, enabling to process thousands of cells per image efficiently; (2) Confirmation of the influence of cell morphology on the distribution of TMP exceeding a critical threshold on the cell membrane; (3) Confirmation of the view that cell morphological features affect the vulnerability of the cell to IRE; (4) Finding of a statistical correlation between the membrane occupancy of where local TMP above the threshold value and the lethal area of cells under the influence of IRE stimulus
Analysis of Electronic and Magnetic Properties at the Interfaces of Transition Metal Heterostructures
No full textMaterial science is a field of physics that bridges the gap between the microscopic properties
of materials and how these properties manifest as tangible, observable characteristics
that can be observed or harnessed for applications. Material scientists grow, analyze, modify,
and model complex, exotic materials to understand emergent, novel phenomena and create
devices which can readily be employed for electronic, magnetic, and other applications. However,
many material properties cannot be measured or observed directly; it is not feasible
to measure the orbital energies of an atom directly or quantify angstrom-scale magnetic
variations in a thin film sample directly. Since these properties are frequently what create
meaningful effects at a macroscopic level, an understanding of them is required that only
material science techniques can provide. This thesis concerns two separate studies of complicated
material systems that require an understanding of their underlying structure and
properties that cannot be directly discerned by experiment alone. These samples belong to a
class of materials known as heterostructures, structures formed by layering multiple materials
with different chemical/elemental compositions. The junctions where different materials in a
heterostructure connect are called interfaces, and serve as the sites of emergent physical and
chemical phenomena with a myriad of electronic and magnetic applications.
The first material system studied is the interface of bulk LaAlO3 and bulk CaTiO3,
often simply abbreviated as LAO/CTO. Systems containing interfaces between transition
metal compounds have been intensely studied within the past two decades because certain
phenomena such as two-dimensional electron gases (2DEG), magnetism, and other effects
tend to appear specifically around the interface. Historically, a combination of bulk LaAlO3 and bulk SrTiO3 (LAO/STO) was studied instead, but the interfacial effects can be changed
by swapping out various elements in the compound. This variation is due to the crystal
structure near the interface being distorted according to the element introduced, altering the
Ti orbital energies near the interface as well. These near-interface orbital energies directly
correlate to observed interfacial phenomena, so swapping elements is expected to affect the
macroscopic electronic and magnetic properties of the system. The difficulty resides in the
fact that orbital energies and 2DEG charge densities cannot be measured directly by any
experiment; rather, they need to be extracted from experimental data via sophisticated
modelling. The purpose of this study was to probe two samples of LAO/CTO with varying
thicknesses, use the extracted experimental data to generate models of the two samples, and
finally use this model to discern orbital energies. Special consideration was given to comparing
and contrasting the difference between the LAO/STO interfacial electronic structure with
that obtained for LAO/CTO. It was found that the orbital energies of LAO/CTO maintain
a significantly different configuration from those of LAO/STO, and suggest that LAO/CTO
may be more promising for magnetic applications. Furthermore, this difference will foster
more investigation into interfaces of this kind, particularly in designing new configurations
of different metals to observe what macroscopic effects they produce.
The second material system studied is thin films of Fe3GeTe2, often abbreviated FGT.
FGT as a bulk material has been studied since the turn of the millennium for potential
magnetic applications, and attention has recently moved towards growing the substance
in thin film form on the order of angstroms thick. Several sources have found that the
electronic and magnetic properties of these thin films vary dramatically vary dynamically as
more FGT film layers are grown sequentially in one sample. However, this information is only known at a high level; the magnetic effects are known to differ, but how exactly this
manifests on a microscopic level is unknown. Given the angstrom level thickness of the films,
it is extremely difficult to probe the magnetic properties in detail. A more sophisticated
technique is needed, so here we apply resonant X-ray reflectometry. This study considered
two samples: a single FGT layer film (monolayer) and a combination of two FGT layers as
a film (bilayer). Experimental results were used to synthesize a model of each film and the
magnetized iron distribution was quantified in each case. The two samples were found to
have differing magnetized iron distributions, further lending credence to observations that
FGT films of various layers will produce different magnetic properties and effects.
These two studies represent intriguing but very limited applications of material science.
New exotic materials are being actively discovered all the time, each with their own unique
need for a method that probes their microscopic properties to understand macroscopic phenomena.
Material science techniques are and will continue to be important for these reasons;
advancement of technology is now reliant on synthesizing and understanding new materials
that improve electronic and magnetic infrastructures, an understanding that material science
provides
A Theoretical Examination of Contributing Factors to the Proliferation of Political Vigilantism: Evidence from Ghana.
No full textPolitical vigilantism has been a significant issue in many parts of the world, and it has undermined the rule of law and democratic processes in Ghana. Political vigilantism is understood as actions taken by individuals and/or quasi-institutions other than state officials which could either be extralegal or illegal mostly typified by violence in the political field. Ghana, in particular, has been affected by political vigilantism, and it is considered a major obstacle to political development in the Fourth Republic. This study uses an institutional performance-focused theoretical framework comprising the theories of structuration, legitimacy, institutional failure, and social learning to test the significance of the identified factors contributing to the prevalence of political vigilantism. The study employs a mainly qualitative methodology to answer the research question: “Does the theoretical framework explain the contributing factors of political vigilantism in Ghana?” The findings indicate that key state institutions have failed to fulfill their constitutional mandates and that political interference has motivated the spread of vigilante activities in Ghana. The results further suggest that a combination of factors, including unemployment, poverty, high illiteracy rates, and politicians’ desire for power, has sustained political vigilantism. Finally, the study recommends that allowing institutions such as the electoral commission and criminal justice agencies to work independently and without political influence will reduce the prevalence of political vigilantism, which has marred the beauty of Ghanaian democracy. This study contributes to our understanding of political vigilantism and its implications for theory, policy, laws, and further research. In conclusion, without institutional independence and strict adherence to the rule of law, political vigilantism will continue to be a major issue in Ghana’s political development
Study of Canola Meal Extract in the Synthesis of Lipids by Mortierella alpina
No full textQuality and cost-effective raw materials and the utilization of agriculture by-products with potential
quality attributes and negligible commercial value can be supplemented in several microbial
processing industries. Canola meal (CM), a by-product of canola processing, has an excellent
nutritional profile composed of protein, carbohydrates, vitamins, and minerals, and could serve as a
potential candidate for microbial culture media. Saskatchewan, as a global leader in canola
production, has plans for upscaling its canola processing facilities. The efficient utilization of canola
meal extract (CME) in the production of lipids and polyunsaturated fatty acids, such as arachidonic
acid (ARA) has the potential to serve as valuable ingredients or base chemicals for food, feed, and
nutraceutical industries. This current study focused on the incorporation of alkaline extract (AE) and
subcritical extract (SE) of CM in a culture medium of an oleaginous fungus, Mortierella alpina
ATCC 32223, by replacing conventional yeast extract (YE) at a level of 50 % and 100 %. Extraction
for AE was conducted at 75 °C with a pH of 10.5, while for SE, it was carried out at 160 °C without
pH control. Initial trials were conducted to examine the effect of aeration at a level of 0.5 to 2.0 vvm
on fungal growth and it was found that increasing aeration rate increased fungal growth rate from
0.16 day-1 to 0.39 day-1. Also, the ARA percentage in the lipid increased from 10.39% to 21.86%. It
became evident that ARA production was positively correlated with biomass accumulation and its
lipid content. During the replacement of YE by CME, it was observed that the 100% substitution of
YE by CME yielded growth results similar to that of the control, which employed standard media
containing YE. Moreover, AE- and SE-supplemented media exhibited a higher ARA accumulation
of 144.91 mg/L and 165.8 mg/L, respectively, in comparison to standard media (124.87 mg/L).
Interestingly, when glucose was omitted from the culture, media supplemented with 100% AE
performed better as compared to standard media. However, the limitation of glucose had an adverse
effect on both the growth and lipid content of the culture