VictorJuiz/thesis huggingface dataset:
Capillarity and convection-controlled assembly in the spreading of particulate suspensions on an air-liquid interface

Self-assembly of particles at interfaces has immense potential for printing and coating applications in biological and industrial processes. Several studies on the spreading of pure fluids on an air-liquid interface have been conducted; however, none have examined the spreading characteristics of two-phase fluid materials. In this work, a drop of concentrated suspension of PMMA particles in silicone oil was placed on an aqueous glycerol solution – air interface. Depending on the initial rate of spreading of the suspension, two outcomes were observed: the particles were either swept away by the spreading suspension or organized into an array of two-dimensional networks. The two outcomes were explained by describing the particle motion as being a result of a competition between fluid convection and capillary attraction. This description was confirmed by performing experiments for different particle sizes, volume fractions, the viscosity and salinity of the substrate on the spreading behavior and pattern.

Keywords: Fluid Dynamics
Interfacial Science
Self-assembly
Suspension
Advisor: Ramachandran, Arun
Active Balancing and Online Electrochemical Impedance Spectroscopy for Electric Vehicle Battery Management

The Electric Vehicle (EV) battery system performance-to-cost ratio has been identified as a roadblock in the mass commercial adoption of EVs. This ratio can be increased by improving the models and management algorithms used in the Battery Management System (BMS). In this work, the potential for impedance-based battery models to enable such BMS improvements is explored. A power management architecture featuring active balancing and high-current online Electrochemical Impedance Spectroscopy (EIS) for real-time model identification of high-capacity, low-impedance automotive cells is proposed and experimentally demonstrated. The active balancing system eliminates the vehicle's auxiliary power supply and incurs less cost than existing designs. The high-current EIS is enabled by a hybrid linear and switched-mode power architecture. The final vision of this work is the implementation of an EV BMS with real-time model identification and advanced model-based balancing, and the analysis and results here represent a starting point toward achieving that vision.

Keywords: active balancing
battery
battery management system
electric vehicle
electrochemical impedance spectroscopy
lithium
Advisor: Trescases, Olivier
Nickel-Catalyzed Cyanation of Benzylic and Allylic Pivalates

Nitriles are considered very versatile functional groups due to their ability to easily be transformed into a variety of other functional groups in one or two steps. In particular, the synthesis of α-arylnitriles is of interest to organic chemists due to their presence in pharmaceuticals and their value as synthetic intermediates. Taking advantage of nickel’s unique ability to insert into a C‒O bond, the focus of this thesis is on the nickel-catalyzed cyanation of benzylic and allylic pivalates, exploring the use of inorganic and organic cyanide sources for this transformation. The substrate scope for the synthesis of benzylic and allylic nitriles will be presented as well as studies examining the functional group tolerance of this cyanation reaction, which led to further insights into the mechanism and applicability of this chemistry.

Keywords: Cyanation
Nickel catalysis
Nitrile
Advisor: Rousseaux, Sophie A.L.
Organic Materials as Charge Transport Layers: A Relationship Strengthened by the Chemistry of PEDOT:PSS and Hemiporphyrazine Derivatives

The aim of this thesis was to study and develop new charge transport materials for the application of organic photovoltaic (OPV) devices. The hole-transport material studied was a variation of the commercial product, poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS); in which a synthetic derivative was created, poly(3,4-ethylenedioxythiophene)/poly(styrene)-graft-poly(styrene sulfonate) (PEDOT:PS-g-PSS), to act as a hole-transport layer. Initial conductivity results indicted its potential to be processed for use as a transparent conducting electrode for flexible OPVs. It’s complementary layer, the electron-transport material, focused on hemiporphyrazines and molecular derivatives of this macrocyclic ligand. In particular chloro-aluminumhemiporphyrazine (Cl-AlHp) possessed electrochemical properties that were compatible with OPVs, and ultimately was integrated into a device with results showing functionality.

Advisor: Bender, Timothy P
Intelligent Medical Devices for Brain State Classification and Responsive Neuromodulation

Recent advances in implantable electronics, machine learning and fundamental neuroscience have enabled the individualized artificial control of neural systems. This has led to breakthrough therapies for neurological disorders such as epilepsy. This thesis describes the design and implementation of a framework for chronically-implanted, intelligent devices for neural signal recording and responsive stimulation. The low-power signal processing required to extract pathological biomarkers is described, and the process of classifying brain states based on such biomarkers is outlined. A hardware-efficient approach to time-series classification is introduced: the exponentially decaying memory support vector machine (EDM-SVM). Biomarker extraction, classification, and chronically-safe neurostimulation is integrated in an implantable integrated circuit: the neural interface processor (NURIP). The continuous adaptation of NURIP over the lifetime of an individual is essential to maximize classification accuracy and treatment efficacy. The design of a patient-localized device training microserver is described to achieve this goal.

Keywords: Brain State
Classifier
Machine Learning
Medical Devices
Neuromodulation
Signal Processing
Advisor: Genov, Roman
Valiante, Taufik A
A Fully-Connected Boltzmann Machine with Virtual FPGAs

This thesis introduces a 1024-node hardware for a Boltzmann machine, implemented in an Arria 10 field-programmable gate array (FPGA). This system consists of a network of connected nodes, the states of which undergo changes during a procedure termed annealing. Large memory resources required to save connectivity data are the main factor preventing the increase of the design's size and complexity. To alleviate this, an extension approach, whereby a problem is divided into sub-problems (virtual engines) which successively undergo annealing, is examined. Several parameters of this scheme are evaluated based on two metrics, leading to the conclusion that there is an optimal number of engine swaps for good performance, and that cyclically selecting engines improves the outcome. The extension method is demonstrated through a hardware prototype (with a personal computer as a controller) that can be a starting point for interface design and timing characterization.

Keywords: Boltzmann machine
Combinatorial optimization
FPGA
Ising model
Advisor: Sheikholeslami, Ali
Investigating Alternative and Emerging Pasteurization Techniques for Human Milk Preservation

The effect of Holder (62.5°C, 30 minutes), flash-heating (brought to boil), UV-C (250nm, 25 minutes) and high hydrostatic pressure (HHP, 500MPa, 8 minutes) pasteurization on human milk composition was studied. Seventeen pools of human milk from different women underwent each of the 4 pasteurization techniques. Macronutrient, vitamin C and folate and bioactive components (bile salt-stimulated lipase (BSSL), lysozyme, and lactoferrin) were measured in raw and pasteurized milk to determine any losses. Bacteriology was carried out to assess the ability of each technique to yield a negative culture (

Keywords: Flash-heating
HHP
Holder
Human Donor Milk
Nutrients and Bioactives
UV-C
Advisor: O'Connor, Deborah L
Practical Implementation of Flying Capacitor Based Multilevel Converters On-Chip and a Practical Single-Mode Controller with Near Minimum Deviation Transient Response

The work presented in this thesis focuses on the practical implementation of techniques to reduce the volume of the output filter capacitor and inductor. The first area of focus will be the on-chip implementation of flying-capacitor based multilevel converters, which have been shown to reduce inductor volume. One such converter, the 7 Switch Flying Capacitor (7SFC) Buck, is implemented with gate driving on-chip. In doing so, floorplanning and layout strategies for multi-level converters were developed and are described. As compared to conventional solutions, the volume is reduced while achieving better efficiency for most operating points. Also presented is a simplified single-mode controller with near minimum deviation transient response for output capacitor volume reduction. This controller achieves similar volume reduction as compared to multi-mode solutions while eliminating dual-mode operation and associated toggling and issues. This controller is demonstrated in a single-phase buck converter based prototype with extensions to other topologies proposed.

Keywords: Circuit
Control
Integrated Circuit
Minimum Deviation
Power Management
SMPS
Advisor: Prodic, Aleksandar
Investigating the Solidity Principle in Domestic Dogs (Canis lupus familiaris)

The solidity principle (SP) dictates that solid objects cannot pass through each other or exist in the same location. Investigations in human and nonhuman primates have demonstrated that they understand SP, and suggested it may be central to navigating the environment. Research in canines has been inconclusive. Controlling for confounds in previous studies, I tested domestic dogs’ understanding of SP in a between-subjects design using an apparatus consisting of a removable shelf with 2 vertically aligned search locations. Dogs (N=48) watched a treat fall into the apparatus and come to rest on either the shelf or the bottom surface. Three different experiments were designed to partially or fully obscure both of the search locations. In partially occluded experiments dogs showed near ceiling search accuracy, suggesting a basic understanding of SP. Dogs in the fully-occluded experiment performed at chance. This study sheds light on physical concept understanding in non-primate social animals.

Keywords: Canine Cognition
Comparative Cognition
Continuity
Domestic Dog
Physical Reasoning
Solidity
Advisor: Buchsbaum, Daphna
Moscovitch, Morris
Evidence for Synaptic Vesicle Binding by the C-terminal of a Short Splice CaV2.1 Calcium Channel

Action potential evoked neurotransmission is gated by Ca2+ influx through voltage-activated calcium channels (CaVs), predominantly CaV2.1 and CaV2.2. It is generally accepted that synaptic vesicles (SVs) must be tethered near the channel pore to allow for the timing of fast, synchronous transmission, however, the molecular identity of this tether remains unknown. Previously our lab developed an in-vitro SV pull-down assay (SV-PD) to directly test SV-binding. We demonstrated that the intracellular C-terminal of the chick CaV2.2 binds SVs via a conserved motif. Here we use SV-PD combined with mutant protein and blocking peptide approaches to characterize SV-binding by the C-terminal of the newly cloned chick CaV2.1. We find that the CaV2.1 C-terminal can bind SVs at a more proximal site via the same motif identified in CaV2.2 and this binding is subject to modulation by alternative splicing. These findings suggest that CaV2.2 and CaV2.1 can tether SVs through the same molecular mechanism.

Keywords: Calcium channels
Presynaptic
Synaptic Vesicles
Tethering
Advisor: Stanley, Elise F
Measurements and modeling of low-stress creep deformation in two opto-electronic glass-epoxy joints

The present work studied low stress creep deformation of two epoxy adhesives used in opto-electronic applications. A novel, laser-based method of non-contact creep strain measurement was used for monitoring deformation during bulk tensile creep tests. Another novel method, using optical interference fringes, was used to measure the minute deformations of specially designed glass opto-electronic specimens. These tests were conducted at multiple temperatures and stress levels for each material. It was shown that creep models in Ansys™, as fitted to the tensile creep data, can be used to model the creep deformation of the opto-electronic joints at low stress. The high modulus adhesive initially appeared to be linearly viscoelastic, however opto-electronic tests showed that this material exhibited non-linear creep behavior at very low stress levels. The lower modulus adhesive was shown to be linearly viscoelastic over the entire range of stresses encountered in the opto-electronic joints.

Keywords: Adhesive joints
creep
Epoxy
Fiber optic device
Interferometry
Viscoelasticity
Advisor: Spelt, Jan K
Retroreflective Binary Huygens' Metasurface

This thesis discusses the ability to aggressively discretize a periodic surface to retroreflect an incident wave. The novelty of this work is related to the number of cells that are needed per grating period to obtain perfect retroreflective power efficiency. For an incident angle greater than 19.5 degrees from normal, perfect retroreflection is possible when considering a passive system having only two cells per grating period. This thesis reports the design and demonstration of near-grazing angle retroreflection metasurfaces for both TE and TM polarizations. Such aggressive discretization lessens, as much as possible, the need for small feature sizes, and results in a simple metasurface retroreflector that is extremely power efficient, cost-efficient and scalable to mm-wave and THz frequencies. Because of its simplicity, this approach can be used to realize electrically large retroreflectors that are very challenging for the standard Van Atta approach which requires complex wire routing.

Keywords: Diffraction
Electromagnetics
Huygens
Metasurface
Reflection
Retroreflection
Advisor: Eleftheriades, George V
Biogeography and comparative phylogeography in three fish species of the eastern Guiana shield.

Comparative phylogeography allows us to investigate the relative importance of species specific biological characteristics versus shared historical conditions on species diversification in a region by studying sympatric populations of different taxa. To examine species specific versus shared evolutionary trajectories of freshwater fishes in the Guiana Shield region of South America, I analyzed and compared the population structure of three co-distributed species of the weakly-electric fish genus Gymnotus using mitochondrial gene sequences (cytochrome b). Population analyses indicate that, generally, Gymnotus species show a lack of contemporary gene flow between drainages. The phylogenetic relationship of fish populations between drainages, however, is not congruent among species. These results suggest that, while historical geological events such as the formation of drainages are important for the diversification of freshwater fish species, individual biological attributes, such as dispersal ability, likely play an influential role as well.

Keywords: Biogeography
Comparative Phylogeography
Ecology
Freshwater Fish
Gene flow
Population Genetics
Advisor: Lovejoy, Nathan R
Dynamic Kinetic Resolution and Stereoselective Molecular Recognition of α-Amino Acids

Amino acids are ubiquitously found in biological systems and pharmaceuticals. As a result, there is immense interest towards developing stereoselective methods of amino acid synthesis. The research described herein is a continuation of past research efforts in our group in the areas of chiral molecular recognition and enantioselective transformations of amino acids. Chapter 1 describes the use of dynamic kinetic resolution (DKR) to convert inexpensive L-amino acids to their unnatural D-isomer with up to 92% yield and up to >98% ee. The use of a hydrophobic chiral guanidine in combination with an electron deficient pyridoxal analogue was crucial for reactivity. Chapter 2 discusses the development of a method towards the stereoselective molecular recognition of unprotected α-amino acids using boronic acids achieving >95% d.r. and up to >98% ee. Our system proved to be amenable towards computation and all calculations are well supported by experimental data.

Keywords: Amino Acids
Boron
Resolution
Stereoselective
Advisor: Chin, Jik
Accurate Mutation Detection in Cancer Through Improved Error Suppression and Quantification of Molecular Complexity

DNA from cancer cells is often masked by nucleic acids from normal cells in tumour tissues and blood plasma, resulting in low allele frequency mutations. Next-generation sequencing has enabled detection of somatic alterations, however it is limited by sequence errors. A promising strategy to suppress errors utilizes unique molecular identifiers (UMIs) to amalgamate reads from the same molecule into a consensus sequence. While current methods depend on redundant sequencing of template molecules, we have developed an error suppression strategy that only requires single reads. We expanded UMIs with sequence properties to enhance molecular quantification, which reduced single-strand consensus errors up to 70% for deep sequencing. Additionally, we suppressed errors down to 1 x 10-4% in a quarter of single reads with moderate sequencing coverage. Using complementary strands of single reads, we improved recovery of double-strand molecules by 5-fold. Together, our method enabled sensitive mutation detection below 0.1% frequency.

Keywords: Allele
Cancer
Error suppression
Molecular complexity
Mutation
Sequencing
Advisor: Pugh, Trevor J
Bratman, Scott V
Voluntary Self-Regulation BCI with Real-Time User Feedback in an Adolescent Population

Individuals with severe motor impairment have little motor control, making them unable to perform everyday tasks independently. Brain computer interfaces (BCIs) use detectable changes in neurophysiological signals to control external communication and mobility enhancing devices in the absence of speech and body language. A limitation of current BCIs is their dependence on the performance of mental tasks which can be non-intuitive in the context of a communication activity. This study explored self-regulation BCIs using near- infrared spectroscopy (NIRS) in an adolescent population. Fifteen youth participants were able to control the BCI via voluntary self-regulation, achieving classification accuracy of 77.9 ± 8.8% after only two sessions of real-time user feedback. Self-reported ease-of-use ratings were statistically similar between self-regulation and pre-defined task paradigms. These findings suggest that voluntary self-regulation can be an effective means of BCI control in youth and is not perceived as more difficult than conventional task-based BCI.

Keywords: Brain-Computer Interface
children and youth
motor impairment
near-infrared spectroscopy
voluntary self-regulation
Advisor: Chau, Tom
High Power Density, Four-Quadrant, DC-AC Converter using Wide-Band Gap Semiconductors and Active Power Decoupling

The challenges in building high power density single-phase inverters are explored in this work, for Photovoltaic (PV) and Electric Vehicle (EV) applications. A hybrid Hysteretic Current-Mode Control (HCMC) system is developed that reduces the volume of the inverter system. Leveraging on this control scheme, two inverter designs are developed: 1) an EV power-hub, and 2) an off-grid PV inverter. The power-hub operates in four different modes: Grid-to-Vehicle (G2V), Vehicle-to-Grid (V2G), Vehicle-to-House (V2H), and the novel Vehicle-to-Vehicle (V2V) mode. The off-grid PV inverter is composed of three single-phase sub-inverters that equally share the load power. The partial substitution of electrolytic bus capacitors with an Active Power Decoupling (APD) module, reduces the total inverter volume by 17.6%. A CEC efficiency of 95.05%, an average THD of 4.2%, a total volume of 31 in3, and a power density of 64.5 W/in3 is achieved.

Keywords: Active Power Decoupling
Electric Vehicle
High Power Density
Hysteretic Current Mode Control
Inverter
Soft Switching
Advisor: Trescases, Olivier
Multicolour optogenetics for studying the roles of cAMP and cGMP in synaptic plasticity and memory

Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) are major interactive signalling molecules involved in a variety of physiological systems. However, due to a lack of available techniques for investigating their spatiotemporal interactions, the functions of their signalling cascades are not entirely known. To study the interactive roles of cAMP and cGMP in the nervous system, I established a multicolour optogenetic method for selectively activating cAMP/cGMP signalling by utilizing the combination of blue light-sensitive adenylyl cyclase (PAC) and green light-sensitive rhodopsin guanylyl cyclase (RhGC). By two-photon photoactivation at target synapses, I revealed bidirectional regulation of structural plasticity by cAMP/cGMP signalling. Also, I demonstrated suppression of novel object recognition memory by cGMP, but not cAMP, using photoactivation in freely behaving mice. Thus, this novel optogenetic technique enables direct investigation of spatiotemporal cAMP/cGMP functions and will serve as a valuable tool for studies of their signalling in broad fields of research.

Keywords: cAMP
cGMP
hippocampus
memory
optogenetics
plasticity
Advisor: Okamoto, Kenichi
Performance characterization of rock bolts through in situ pull tests

In Ontario underground hard rock mines rock bolts are the principal reinforcement element of ground support systems. This thesis investigates rock bolt response to in situ pull test conditions. A database of 1,924 pull tests from 18 mines across Ontario was assembled. The performance of rock bolts was quantified, identifying the influence of installation, rock bolt and rock mass parameters on the resulting in situ behavior. A statistical analysis provided the means to construct representative behavior. Furthermore, the behavior of resin grouted rebar was analyzed using numerical models. A series of numerical simulations of resin grouted rebar pull tests were undertaken to illustrate bolt response in underground conditions. These investigations provide insights in understanding the behavior of resin grouted bolts in explicit models and indicated how this information can be used in stability analysis.

Keywords: Pull Test
Rock Bolts
Underground Mining
Advisor: Hadjigeorgiou, John
Continuity of Care and Oncological Expertise for Patients with Active Cancer who require Emergency Department Care: A Population-Based Assessment

Patients with cancer have complex care requirements that may result in an emergency department (ED) visit. In this retrospective cohort study, Ontario health databases were used to identify 42,820 qualifying patients who received chemotherapy or radiation in the 30-days prior to a cancer-related ED visit. Using multivariable models and propensity score matching, odds of hospitalization were lower in patients treated at alternative EDs compared to original EDs, but there was no difference in mortality, return ED visits or CT imaging. For patients seen at an alternative general hospital, the adjusted odds of hospitalization were again lower when compared to patients seen at original hospitals/cancer centres, but 30-day mortality and return ED visits were higher and CT imaging was lower. The results of this study suggest that the cancer expertise of an institution, rather than continuity of care, may be an important predictor of outcomes following emergency treatment of cancer patients.

Keywords: Administrative Data
Emergency Medicine
Epidemiology
Health Services
Oncology
Advisor: Atzema, Clare L