Master's Theses (2009 - )

Permanent URI for this collectionhttps://hdl.handle.net/1807/9947

The School of Graduate Studies (SGS) requires doctoral and masters graduands to submit a thesis written as a required element of their degree program in electronic format.

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SGS intends to house all available digitized Doctoral and Masters theses by U of T graduate students on this site. The current collection is but a small sample of that scholarly work.

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1,1-Hydroboration and Borane Adduct of Diphenyldiazomethane
(2018-06) Tang, Connie; Stephan, Douglas W.; Chemistry
The advent of frustrated Lewis pair chemistry has demonstrated unique reactivity with a variety of small molecules. This thesis explores related chemistry with reactions of diazomethanes and highly electrophilic boranes. Diphenyldiazomethane Ph2C(N2) reacts with HB(C6F5)2 resulting in 1,1-hydroboration via a concerted reaction involving initial formation of the Lewis adduct, yielding the robust amino-borane product Ph2CN2BH(C6F5)2. Alternative synthetic routes to this product are detailed, as well as a related salt. Conversely, Ph2C(N2) reacts with B(C6F5)3 to form a highly sensitive adduct Ph2CN2B(C6F5)3. This product liberates N2 and is proposed to generate Ph2CB(C6F5)3. DFT calculations reveal that formation of this product is thermodynamically favourable from the starting compounds of carbene, N2 and borane. The isolation of this latter species opens the possibility that judicious choice of a Lewis acid and base could provide an avenue to metal-free fixation of N2.
A 1.25GS/s 8-bit Time-interleaved C-2C SAR ADC for Wireline Receiver Applications
(2013-12-11) Wang, Qiwei ; Carusone, Anthony Chan ; Electrical and Computer Engineering
Many wireline communication systems are moving toward a digital based architecture for the receiver that requires a front-end high-speed ADC. This thesis proposes a two-level time-interleaving topology for realizing such an ADC, comprising front-end time-interleaved sub-rate track-and-holds each followed by a sub-ADC which is further time-interleaved to a slower clock frequency. The design, implementation and measurement of the 1.25GS/s sub-ADC fabricated in 65nm CMOS technology is presented. The SAR architecture is chosen for its low power and digital friendly nature along with an unconventional C-2C capacitive DAC implementation for higher bandwidth. The time-interleaved C-2C SAR ADC runs with a 1.0V supply, and it has a full input range of 1.0V\subscript{pp} differential, while consuming 34mW. The SNDR is 39.4dB at low frequency and the FOM is 360fJ/conv-step and 428fJ/conv-step at low and Nyquist input frequencies respectively. The SNDR is 34dB at 4GHz input frequency, which is more than 6 times the Nyquist frequency.
111In-labeled Nimotuzumab Modified with Nuclear Localization Sequences (NLS): An Auger Electron-emitting Radiotherapeutic Agent for EGFR-overexpressing and Trastuzumab-resistant Breast Cancer
(2011-08-24) Fasih, Aisha ; Reilly, Raymond Matthew ; Pharmaceutical Sciences
Objective: The cytotoxic property of anti-EGFR-1 monoclonal-antibody nimotuzumab modified with nuclear localization sequence and radiolabeled with 111In was evaluated in trastuzumab-resistant breast cancer cells. Methods: 111In-nimotuzumab-NLS was constructed and its immunoreactivity was determined. Cellular and nuclear uptake was evaluated by cell fractionation. Finally, the cytotoxicity of conjugates (111In-nimotuzumab/111In-nimotuzumab-NLS) was studied by clonogenic assays. Results: The immunoreactivity of 111In-nimotuzumab-NLS was conserved. 111In-nimotuzumab-NLS exhibited 2-fold higher nuclear translocation as compared to 111In-nimotuzumab in MDA-MB-468 cells. Nuclear importation of 111In-nimotuzumab-NLS in MDA-MB-468 cells was 4-fold and 6-fold higher than moderate and low EGFR expressing cell lines, respectively. Clonogenic survival (CS) for MDA-MB-468 cells showed 111In-nimotuzumab-NLS to be 10-folds and 60-folds more potent than 111In-nimotuzumab and nimotuzumab, respectively. Moderate killing for TrR1 and MDA-MB-231 was observed. 111In-hEGF showed significantly higher cytotoxicity and 2-fold higher γ-H2AX foci integrated density/nuclear-area as compared to 111In-nimotuzumab-NLS. Preserved selectivity of 111In-nimotuzumab-NLS makes it an excellent drug for treating cancers.
13-deoxytetrodecamycin and Thamamycin: Two Promising Tetrodecamycin Antibiotics
(2021-09) Lefebvre, Maxime; Nodwell, Justin JN; Biochemistry
Antibiotic-resistant bacteria pose a serious threat to modern medicine. Methicillin-resistant Staphylococcus aureus (MRSA) is among the most alarming pathogens due to its prevalence in hospitals and the community and the emergence of multi-drug resistant isolates. 13-deoxytetrodecamycin (13-dTDM) and thamamycin (THM) are novel, related members of the tetrodecamycin antibiotic class that are bioactive against MRSA. Presently, their targets and mode of action are unknown although their structural novelty and potency against drug-resistant bacteria makes them very attractive subjects for research. The aim of this thesis was to increase the yield of 13-dTDM and THM in order to elucidate their molecular target and mode of action. Utilizing a ‘ribosome engineering’ approach, I have successfully increased the yield of THM. I also demonstrate that 13-dTDM and THM are bactericidal and do not target the lipid II cycle of cell wall biosynthesis. Lastly, preliminary data suggests possible targeting of the folate pathway by THM.
A 1Mbps 0.18μm CMOS Soft-output Decoder for Product Turbo Codes
(2009-07-30T15:09:57Z) Bade, Peter ; Gulak, P. Glenn ; Electrical and Computer Engineering
A product turbo code (PTC) decoder application specific integrated circuit (ASIC) is designed in 0.18μm 1P6M CMOS with embedded SRAM. From simulation, an operating frequency of 73.1 MHz at typical conditions is obtained, yielding a throughput of 3.8 Mbps with 4 decoding iterations, while consuming 103.4 mW. The total area is 5.13 mm2. Assuming the ASIC would be used as a hard macro, the area could be reduced to 1.7 mm2. The ASIC was tested at 20 MHz under typical conditions, which resulted in a throughput of 1.0 Mbps at 1.8V supply while consuming 36.6 mW. By making a slight modification, this design can be easily scaled to support IEEE 802.16d WiMAX. Allow for this, and moving to a 45nm process an estimated throughput of 9.44 Mbps with 4 iterations can be obtained. Total macro area would be approximately 0.11 mm2.
2 2D Model of Semi-molten Drop Impact for Thermal Spray Application
(2009-07-15T13:38:06Z) Wu, Tommy ; Mostaghimi, Javad ; Bussmann, Markus ; Materials Science and Engineering
In thermal spraying, semi-molten (or partially-melted) particles are likely to form when the sprayed particles are insufficiently heated, or when a composite material is deposited. The present 2D model serves to begin to assess the spreading behavior of a semi-molten particle when impacting a solid substrate. An Immersed-Boundary (IB) scheme was implemented in an axisymmetric fluid model to simulate fluid flow in the presence of a solid core. The IB method calculates a forcing term, which is added to the momentum equation, to enforce the no-slip boundary condition at the core surface. Results are presented for the impact of a semi-molten tin droplet of radius R for a wide range of solid core radii r, varying the drop size ratio r/R, and the impact velocity Uo.
2 mm Bipolar Cautery Instrument for Robot-assisted Neuroendoscopy
(2020-11) Lutfallah, Claudia; Drake, James M; Biomedical Engineering
Electrosurgery is used in the operating room as a means to cut tissue and maintain hemostasis. Bipolar cautery can be very useful in helping neurosurgeons treat hydrocephalus by cauterizing the choroid plexus to reduce cerebrospinal fluid production; however, current instrument designs are not well suited to a typical neuroendoscopic working channel due to their rigid structure, limited range of motion, and bulky design. A novel minimally invasive bipolar cautery tool suitable for flexible neuroendoscopy has been developed to solve this issue. The system features bipolar tips that resemble grasping forceps, making it easy for surgeons to hold tissue while performing electrosurgery. The tool is compatible with a concentric tube surgical robot and has preserved the intended function of an electrosurgical tool, making it easier to access to miniature anatomies, increase range of motion, and improve surgical outcomes.
200 GHz Circuit for Qubit Interrogation and Readout by Transmission
(2024-11) Jager, Thomas Johann; Voinigescu, Sorin P; Electrical and Computer Engineering
In this thesis, the readout of a silicon spin qubit by transmission at 200 GHz is investigated. The circuit presented, designed in a 22 nm FDSOI process, is intended to detect the quantum-state-dependant shift in resonant frequency of an LC tank. On-die mmWave frequency triplers are included to allow for characterization in a cryogenic probe station, with no external signals above 67 GHz. Using a variable capacitance as a room-temperature-compatible device-under-test, the ability to detect a change in impedance was verified. To the best of the author's knowledge, this is the highest-frequency circuit designed for RF readout of silicon qubits. Operating at 200 GHz reduces the size of certain passive components, such as hybrid couplers and resonator inductors, enabling further monolithic integration of quantum computers.
200GS/s Analog to Digital Converter Frontend in SiGe BiCMOS
(2022-11) Cooke, Gregory Adam; Voinigescu, Sorin P; Electrical and Computer Engineering
This thesis investigates time-interleaved analog to digital converter front end circuits for use in next-generation fiber optic receivers capable of 200 GS/s with analog bandwidths reaching up to the Nyquist frequency. Measurements were conducted on an existing time-interleaved ADC front end which displayed record-breaking performance while sampling at 200 GS/s. A full four-way 200GS/s time-interleaved ADC front end employing a novel architecture was designed and fabricated in a 55nm SiGe BiCMOS process technology. The constituent track and hold amplifier was measured and achieved a record-breaking 101 GHz of track mode bandwidth. Finally, a 60GHz digitally-controlled oscillator was also designed and fabricated in 22nm FDSOI-CMOS technology with the goal of producing on-chip high-frequency clock signals to enable a full time- interleaved ADC front end system on chip.
A 2Gbps Optical Receiver with Integrated Photodiode in 90nm CMOS
(2011-12-20) Rousson, Alain ; Carusone, Anthony Chan ; Electrical and Computer Engineering
The objective of this work was to integrate an optical receiver in a modern standard technology in a form amenable to multiple lanes. To accomplish this goal, a photodiode was integrated with the receiver in a standard 90nm CMOS process and the nominal process voltage of 1.2V was not exceeded. Two optical lanes were integrated on chip with a pitch compatible with existing industry photodiode arrays. This work uses a non-SML photodiode to increase optical responsivity to 0.141A/W, almost 3 times higher than values typically reported for SML photodiodes. This receiver is the first integrated optical receiver reported in a standard CMOS technology with a feature size smaller than 0.13μm, which is necessary for the eventual integration of optical receivers with modern digital processing blocks on a single die. The traditional analog equalizer used in most integrated optical receivers is replaced with a high-pass filter and hysteresis latch for equalization. The receiver occupies a core area of 0.197mm2 and has an optical sensitivity of -3.7dBm at a 2Gbps data rate, while consuming 46.3mW.
3-Methylcholanthrene Induces Chylous Ascites and Lethality in Tiparp Knockout Mice
(2015-11) Cho, Tiffany Elizabeth; Matthews, Jason; Pharmacology
The aryl hydrocarbon receptor (AHR) is a ligand-regulated transcription factor that is activated upon binding to various ligands. The activated AHR modulates the expression of many genes including cytochrome P450s (CYPs) such as Cyp1a1, Cyp1b1, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible poly(ADP-ribose) polymerase (Tiparp). We recently reported that TIPARP is a transcriptional repressor of AHR and Tiparp knockout mice show increased sensitivity to dioxin-induced toxicities. Because of these findings, we examined the sensitivity of Tiparp knockout mice to 3-methylcholanthrene (3-MC), another potent AHR ligand. Tiparp knockout mice treated with 100mg/kg of 3-MC exhibited increased hepatotoxicity, increased lipolysis, and developed chylous ascites compared with treated wildtype mice. No treated Tiparp knockout mice survived beyond day 16; all wildtype mice survived the 30 day treatment. Collectively, this thesis shows that Tiparp knockout mice exhibit increased sensitivity to 3-MC-induced toxicity and lethality supporting our previous findings that TIPARP is an important negative regulator of AHR activity.
3-year Outcomes of Cannabis use Patterns: Evidence from a Longitudinal Survey
(2019-11) Chen, Tongtong; Le Foll, Bernard; Pharmacology
Objectives: We investigated the 3-year follow up on cannabis use disorder (CUD) of cannabis users with different use patterns, as defined by Lower Risk Cannabis Use Guidelines. Methods: Data was obtained from the US surveys NESARC wave 1 (2001-2002) and wave 2 (2004-2005), which included 31,464 respondents with no history of CUD at wave 1. We applied multiple logistic regression and propensity score method to examine the 3-year risk of DSM-IV CUD among different use patterns. The risk of transitioning to higher use frequency was also accessed. Results: Propensity score method showed significant association between lower risk cannabis use and CUD, but not increased use frequency. A significant increase in the risk of CUD was also observed among higher risk cannabis users. Logistic regression showed similar results. Conclusions: The findings suggest that guideline recommended lower risk use pattern may not completely protect an individual from developing CUD.
3D Block Modeling of Geomechanical Properties using Conditional Simulation Method
(2016-11) Eivazy, Hesameddin; Esmaeili, Kamran; Civil Engineering
A thorough understanding of in-situ rock mass geomechanical properties is a key factor for a safe and efficient design of a mining project. Geomechanical properties in a mining project are generally quantified using sample data collected during site investigation. In many mining projects, an exhaustive site investigation to characterize the rock mass properties is impossible. Hence, it is crucial to model the spatial variability of rock mass geomechanical properties using the limited data. This thesis proposes and implements geostatistical simulation approaches for modeling of geomechanical heterogeneity of the rock masses in an iron ore open pit mine. 3D block models for geomechanical properties in different pit areas are generated and verified using statistical methods. The 3D geomechanical models allow the heterogeneity of rock masses to be involved in open pit mine planning and design, as more accurate knowledge of spatial distribution of geomechanical properties promotes safe and economic mine operation.
3D CT to 2D X-Ray Image Registration for Improved Visualization of Infrapopliteal Vessels in Endovascular Procedures
(2024-11) Saderi, Moujan; Wright, Graham A; Medical Biophysics
Chronic limb-threatening ischemia resulting from advanced peripheral arterial disease in infrapopliteal arteries poses a challenge for revascularization, with endovascular interventions suffering from a high technical failure rate. Image fusion technology can enhance the X-Ray Fluoroscopy (XRF) imaging used to guide these procedures, by incorporating vascular maps from pre-interventional Computed Tomography (CT) angiography. This work presents an image registration method designed to facilitate fusion imaging by performing automatic alignment using a single XRF view, based on intrinsic bone landmarks. The method uses an iterative optimization approach, a custom similarity function to quantify alignment, and various strategies to improve capture range and computation time. The proposed method is evaluated on a dataset of images approximating those expected in practice, consisting of cone-beam CT and XRF images of ex-vivo limbs. The results demonstrate sufficient accuracy to identify guidewire deviations from the path of the artery, with average misalignments of <1 mm at the artery.
3D Dental Subsurface Imaging Using Enhanced Truncated Correlation-Photothermal Coherence Tomography
(2019-11) Roointan, Sohrab; Mandelis, Andreas; Mechanical and Industrial Engineering
With dental caries being the most common disease in human, development of accurate and sensitive dental imaging technologies for early caries detection and routine monitoring are crucial for preventive dentistry. However, radiographic technologies fall short of these objectives due to low sensitivity for small lesions and use of ionizing radiation. Here, dental enhanced Truncated Correlation-Photothermal Coherence Tomography (eTC-PCT) is presented as the first 3D tomographic thermophotonic dental imaging modality capable of monitoring and characterizing tooth demineralization with high sensitivity and without ionizing radiation. To this end, eTC-PCT is applied to teeth with natural defects, and artificially generated controlled early caries and surface erosion. Additionally, eTC-PCT performance for dental imaging is compared with other thermophotonic technologies. The results demonstrate that, eTC-PCT is capable of detecting and monitoring early demineralization in teeth at clinically applicable laser power levels, and visualizing the relative progression and extent of lesions through 3D reconstruction.
3D Effects of Synthetic Jet Flow Control on a Stalled Airfoil
(2024-11) Machado, Adnan; Sullivan, Pierre E; Mechanical and Industrial Engineering
This thesis offers an experimental investigation conducted to understand the three-dimensional influence of active flow control on low Reynolds number airfoils. At a Reynolds number of Re_c=10^5 and an angle of attack of α=10°, a NACA 0025 airfoil was first studied in a baseline post-stall condition. The transition to turbulence was visualized, including the Kelvin-Helmholtz instability and shear layer roll-up, as well as the occurrence of large-scale vortex shedding in the wake. The research investigates both low- and high-frequency actuation strategies, utilizing a combination of novel smoke wire visualization techniques and quantitative measurements to evaluate the aerodynamic effects of an array of SJAs on flow reattachment and stability. By visualizing the controlled flow at different actuation frequencies (F+=1.18 and F+=11.76), the study reveals significant spanwise velocities and the formation of coherent structures that contribute to flow control. High-frequency actuation, in particular, demonstrates a greater ability to induce steady flow reattachment and more favorable aerodynamic characteristics compared to low-frequency control. However, the control efficacy diminishes with increasing distance from the midspan, limiting the spanwise control authority to approximately 40% of the SJA array's length. Additionally, this thesis explores energy-efficient flow control strategies by varying the duty cycle and blowing ratio, demonstrating that full flow reattachment can be achieved with duty cycles as low as 5%, leading to significant power savings. The research highlights the trade-offs between increasing the duty cycle or blowing ratio to meet the threshold momentum coefficient for reattachment. Furthermore, diminishing returns in control effectiveness are explained after the sharp initial improvements in the lift coefficient. Despite successful lift recovery, the challenge of extending the spanwise control length with a finite-span array persists, even with high-power control strategies. Lastly, a general three-dimensional model of the reattached mean flow over an airfoil controlled by a finite-span SJA array is developed. The SJA array's control effects create a controlled region where flow separation is suppressed, an uncontrolled region unaffected by the SJA array, and a transitional region bridging these two zones. By integrating multiple visualizations and measurements, a detailed understanding of the shear layer in three dimensions is achieved.
3D Fast Spin Echo T2-weighted Contrast for Imaging the Female Cervix
(2017-03) Vargas-Sanchez, Andrea Fernanda; Beatty, Philip J; Graham, Simon J; Medical Biophysics
Magnetic Resonance Imaging (MRI) with đ 2-weighted contrast is the preferred modality for treatment planning and monitoring of cervical cancer. Current clinical protocols image the volume of interest multiple times with two dimensional (2D) đ 2-weighted MRI techniques. It is of interest to replace these multiple 2D acquisitions with a single three dimensional (3D) MRI acquisition to save time. However, at present the image contrast of standard 3D MRI does not distinguish cervical healthy tissue from cancerous tissue. The purpose of this thesis is to better understand the underlying factors that govern the contrast of 3D MRI and exploit this understanding via sequence modifications to improve the contrast. Numerical simulations are developed to predict observed contrast alterations and to propose an improvement. Improvements of image contrast are shown in simulation and with healthy volunteers. Reported results are only preliminary but a promising start to establish definitively 3D MRI for cervical cancer applications.
3D Hydrogels for Astrocyte/Neural Progenitor Cell Co-cultures
(2016-06) Kesselman, Leah Ranit Baskin; Shoichet, Molly S; Chemical Engineering Applied Chemistry
This thesis explores the use of hyaluronic acid-based hydrogels as extracellular matrix mimics for growing astrocytes and neural progenitor cells in 3D. An examination of laminin- and fibronectin-based peptides showed that modifying gels with peptides containing the adhesive sequence RGD provided the best attachment for astrocytes. Both Diels-Alder and oxime "click" reactions were examined as gelation mechanisms, and oxime-crosslinked gels were used for cell co-cultures. It was determined that astrocytes grown on tissue culture plastic underneath the gels supported neural progenitor cell growth and differentiation better than 3D encapsulated co-cultures. These results demonstrate the importance of co-culture conditions to examine the role of astrocytes on neural progenitor cell fate. Ultimately, engineered matrices, such as those described herein, may provide useful biomimetic environments in which to probe development and/or disease progression in vitro.
3D Laser Written Mirror-Waveguide Circuits for Silicon Photonic Interconnects
(2021-09) Rahimnouri, Amirhossein; Herman, Peter Robert; Electrical and Computer Engineering
An increase in data usage following demands for faster networks over past decades has prompted data centers to scale up the density of channels and boost the network bandwidth. In this way, a new architecture for assembly and packaging of electro-optical (EO) components is now required to facilitate chip-to-chip and chip-to-network interconnections. This thesis employs femtosecond laser writing combined with 3D structural micro-machining for fabricating glass interposers and a new optical printed circuit board (OPCB) platform. The presented glass interposer provided vertical coupling from a plane of multi-core fiber (MCF) arrays to a two-dimensional (2D) grid of silicon photonics (SiP) grating couplers. The OPCB platform demonstrated a wider scope for all-glass optical routing by providing a high-density optical circuit for MCF-to-MCF linking. The interposer and OPCB optical systems provided tight-turning waveguide bends for 3D interconnectivity by developing total internal reflection (TIR) mirrors and 2D hollow-filament gratings photonic crystals (PhCs).
3D Object Detection and Depth Completion for Scene Perception
(2020-03) Ku, Jason; Waslander, Steven L; Aerospace Science and Engineering
3D object detection is a fundamental component in the autonomous driving perception pipeline. While images provide rich semantic information, depth information is lost during perspective projection. LiDAR scans provide accurate depth measurements, but the data is sparse at longer distances. In this thesis, we first propose a method to fuse LiDAR and image features in an end-to-end trainable network to achieve robust, real-time 3D detection performance. Next, to alleviate the sparsity of LiDAR data, we propose a fast, CPU based, depth completion algorithm using only classical image processing techniques, which outperforms several learning based methods. The densified depth map is then used to synthesize virtual views of pedestrians, which are incorporated into a proposed orientation estimation pipeline to improve pedestrian heading estimation. Finally, a monocular 3D detection neural network is proposed, which leverages proposal regression and the task of instance reconstruction using densified object point clouds.

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