Electronic Theses and Dissertations

Permanent URI for this community

https://hdl.handle.net/10388/380

Browse

Now showing 1 - 20 of 11525

A 0.18µm CMOS UWB wireless transceiver for medical sensing applications
(2008) Wang, Xubo; Dinh, Anh van; Khan, Wahid A.; Hsiang-Yung, Teng; Chen, Li; Yang, Shi
Recently, there is a new trend of demand of a biomedical device that can continuously monitor patient’s vital life index such as heart rate variability (HRV) and respiration rate. This desired device would be compact, wearable, wireless, networkable and low-power to enable proactive home monitoring of vital signs. This device should have a radar sensor portion and a wireless communication link all integrated in one small set. The promising technology that can satisfy these requirements is the impulse radio based Ultra-wideband (IR-UWB) technology. Since Federal Communications Commission (FCC) released the 3.1GHz-10.6GHz frequency band for UWB applications in 2002 [1], IR-UWB has received significant attention for applications in target positioning and wireless communications. IR-UWB employs extremely narrow Gaussian monocycle pulses or any other forms of short RF pulses to represent information. In this project, an integrated wireless UWB transceiver for the 3.1GHz-10.6GHz IR-UWB medical sensor was developed in the 0.18µm CMOS technology. This UWB transceiver can be employed for both radar sensing and communication purposes. The transceiver applies the On-Off Keying (OOK) modulation scheme to transmit short Gaussian pulse signals. The transmitter output power level is adjustable. The fully integrated UWB transceiver occupies a core area of 0.752mm^2 and the total die area of 1.274mm^2 with the pad ring inserted. The transceiver was simulated with overall power consumption of 40mW for radar sensing. The receiver is very sensitive to weak signals with a sensitivity of -73.01dBm. The average power of a single pulse is 9.8µW. The pulses are not posing any harm to human tissues. The sensing resolution and the target positioning precision are presumably sufficient for heart movement detection purpose in medical applications. This transceiver can also be used for high speed wireless data communications. The data transmission rate of 200 Mbps was achieved with an overall power consumption of 57mW. A combination of sensing and communications can be used to build a low power sensor.
16 QAM Radio Link on the 5.7 GHz ISM Band
(2003-01) Dielschneider, Jason; Salt, Eric
A wireless data distribution system could be more cost effective than retrofitting cable to a finished building. The radio channel has the disadvantage of being lossy, noisy, and frequency selective. To compensate, the modulator/demodulator needs to be more robust. This thesis investigates the feasibility of implementing a modern wireless data distribution in an in—building environment. The cost of FPGA's is constantly decreasing, making this solution more and more cost—effective as time goes on. The ISM band is used in order to avoid licensing issues. This band requires that spread spectrum modulation with a spreading gain greater than or equal to 10 be used. To get a full complement of music channels on the ISM bandwidth requires a high order modulation scheme. In this study, the feasibility of implementing a 16— QAM modem is investigated. The resulting system is a hybrid modulation scheme with direct sequence spread spectrum modulation in tandem with 16-QAM. The entire system, excluding the RF portion, is implemented on three Altera 100,000 gate FLEX 10KA series FPGA's. The design is specified using Verilog HDL. This facilitates future design changes and ASIC development.
The 18th and 19th century Cree landscape of west central Saskatchewan : implications for archaeology
(2004-12) Dargin, Wade Leslie; Dyck, Ian; Kennedy, Margaret; Meyer, David
The eighteenth and nineteenth century Crees of west central Saskatchewan are the focus of this thesis. This research has involved obtaining information relating to the cultural landscape of these Crees for the period encompassed by the study. An examination of one aspect of this cultural landscape, the named landscape, has been the primary aim of this research. Information regarding the named landscape of these Crees was obtained from relevant historic documents and ethnographic research. A number of historic documents have been consulted in this study. In particular, much use has been made of the journal accounts of Hudson's Bay Company traders who travelled to the study region in the mid 1700s. Ethnographic fieldwork was undertaken with elders from several of the study region's Cree communities who provided information on the traditional named landscape. The relationship that existed historically between the Crees of west central Saskatchewan and their landscape is the subject of this thesis. How this information relates to archaeological interpretations in the study region has also been considered. Guiding this research has been an approach which considers the cultural landscape as representing a socially construed space. An examination of named localities from the study area indicates that the named landscape of the region's Crees did not significantly change over the course of the eighteenth and nineteenth centuries. This suggests that the relationship of these Crees to their landscape, how they conceptualized, structured and organized this environment, also remained largely unchanged throughout this period.
The 18th century western Cree and their neighbours : identity and territory
(1990) Russell, Dale Ronald; Walker, Ernest G.; Linnamae, Urve; Marino, Mary; Waiser, William
The eighteenth century historical documents fail to support the accepted view, advanced by David Mandelbaum and others, that the Cree and Assiniboin invaded the west after 1690 as a result of the introduction of the fur trade. This view, seemingly supported by nineteenth century authorities, has its only source in several brief ambiguous statements published in 1801 by Alexander Mackenzie. The western limits of the Cree and Assiniboin in the early 1700s remain unclear. Their marauding activities against members of the Blackfoot Confederacy occurred only in the late 1700s, almost fifty years after they were documented as peacefully living in central Alberta. In the mid-1700s, six major Cree groups inhabited the western parklands, plains and boreal forest: the Susuhana, Sturgeon, Pegogamaw, Keskachewan/Beaver, Athabasca and Missinipi. These groups were all obliterated by the smallpox epidemic of 1781, and it was the resultant population shifts which were noted by nineteenth century observers.
1H NMR and potentiometric studies of copper (II) speciation in ruminants
(1998-09-01) Attaelmannan, Mohammed Ali; Reid, R. Stephen
Copper is one of the most important trace elements in ruminant nutrition. Its deficiency causes certain pathologies that can be cured by supplementation, by either five ("inorganic") or complexed ("chelated") forms. With the objective of being able to quantitatively compare the distribution of copper between the two forms of supplements, the speciation of copper in ruminant fluids was studied here. For this study, copper lysine supplement was used. It was necessary to first study the acid-base and complexation chemistry of lysine with copper (II). In addition, the complexation chemistry of glycine and histidine, were investigated. Mass balance equations were used to describe the distribution of copper (II) amongst different ligands. The results of the distribution of copper (II) ions in McDougall's solution (a simulated form of bovine saliva), indicate no significant differences in the distribution of copper using the different form of supplements. 1H NMR was used to validate the results from the computer model. Using a combination of the results from the saliva simulation model and the chemical shifts from the NMR studies, the chemical shift changes that would accompany the addition of copper (II) to McDougall's solution were predicted. Results from the models do not show any appreciable differences from experimental values. Rumen samples were collected. Important peaks in the 1H NMR spectrum were assigned. The spectrum indicated that acetic acid, resulting from the fermentation in the rumen, was a good probe for monitoring the speciation pattern. Speciation calculation indicated that the bulk of the copper would be bound to ammonia in the rumen. Changes in chemical shifts that result from the introduction of copper (II) to the rumen contents were predicted. Results were compared with experimental values. Agreement between the two sets of results was found to be satisfactory. The study shows that any advantages that result from the use of copper lysine supplement are not as a result of its remaining intact. Though metal bioavailabilities are hard to predict this approach could help better our understanding of this process. The methods developed here could be extended to other metal complexation problems in biological fluids. (Abstract shortened by UMI.)
2-substituted-1, 3-dioxan-5-ones : synthesis, reactions and synthetic applications
(1998-01-01) Nowak, Pawel; Majewski, Marek
This dissertation deals primarily with synthesis, reactions and synthetic applications of 2-substituted- 1,3-dioxan-5-ones. This class of compounds could be viewed as synthetic equivalents of natures building block--1,3-dihydroxyacetone and could be used in construction of many polyoxygenated natural products. A general, simple, cheap and easy to scale-up synthesis of 2-substituted-1,3dioxan-5-ones was developed. The yields of this three-step procedure, starting form commercially available tris(hydroxymethyl)nitromethane, ranged from 40 to 90%. The exploration of the chemistry of 2-substituted-1,3-dioxan-5-ones was focused on carboanion chemistry of these compounds. 2-Substituted-1,3-dioxan-5-ones were shown to easily form corresponding lithium, boron and titanium enolates. The 2-'tert'-butyl-2-methyl-1,3-dioxan-5-one was deprotonated enantioselectively in 90% e.e. with the aid of chiral lithium amide derived from (R)- or (S)-'N'-(2,2,2-trifluoroethyl)-1-phenylethylamine. This successful outcome was a result of extensive methodological studies. The enolates reacted readily with electrophiles: reactions with aldehydes provided 'anti' aldols in modest to high selectivities in cases of lithium and boron enolates and 'syn' aldols in case of titanium enolate. The enolates could be conveniently trapped as trimethylsilyl enol ethers or as enol acetates, however they failed to react with alkylating agents. The problem was solved using Enders' chiral hydrazone method. The synthetic utility of 2-substituted-1,3-dioxan-5-ones was illustrated in syntheses of (+)-frontalin and several protected ketohexoses. Additionally, the kinetics of deprotonation of a simple ketone with lithium diisopropylamide was investigated in order to shed some light on the mechanism of this type of reaction. The reaction was shown to be first order in ketone and half order in the base, and half order in the base, which suggests a monomer-based mechanism.
The 2009 H1N1 pandemic narrative in newspapers distributed within Saskatoon, Saskatchewan
(2012-08-30) Stoops, Melissa; Abonyi, Sylvia; Findlater, Ross; Hackett, Paul; Oshanek, Daryl; Ahmed, Rukhsana; Janzen, Bonnie
It is known that disease outbreaks, either at a local or a global scale, elicit a social response from the society that it affects which follows a characteristic narrative. An epidemic narrative reflects and shapes the perception of the outbreak. An examination of the mass media provides a glimpse of the epidemic narrative that occurs alongside a disease outbreak. The primary objective of this study is to construct the 2009 H1N1 pandemic narrative from newspaper coverage available in Saskatoon, Saskatchewan, with a focus on how discourse in the news changes over time and geographically. The study draws on and combines three conceptual frameworks: epidemic narrative, anchoring, and framing, in order to construct the pandemic narrative as reflected by the newspaper coverage. The three frameworks were combined to address three aspects of a narrative: 1) there are common stories for common experiences; 2) new stories relate to old stories; and 3) stories of the same experience can have multiple perspectives and interpretations. When combined, these frameworks provide a nuanced understanding and analysis of an epidemic narrative. Articles from four local Saskatoon papers, the StarPhoenix, Saskatoon Sun, Planet S, and The Sheaf and two Canadian national newspapers, the National Post and the Globe and Mail were analyzed for the study. To analyze the articles, an approach referred to as qualitative content analysis was adapted. The primary focus of this approach is on the discourse and meanings of the text. The study provides an overview of the evolving newspaper coverage of the 2009 H1N1 pandemic in newspapers distributed within Saskatoon, Saskatchewan. The findings of the study highlight the importance of meaning and how meanings are constructed and reflected with a narrative. The findings also show how the broader socio-cultural context influences a narrative. The results illustrate the difficulties with communication during a fluid and uncertain situation such as a pandemic. This work can provide a basis for communication advice for future disease outbreaks.
A 2D across-the-channel model of a polymer electrolyte membrane fuel cell : water transport and power consumption in the membrane
(2006-07-05) Devulapalli, Venkateshwar Rao; Phoenix, Aaron; Nemati, Mehdi; Evitts, Richard W.; Baranski, Andrzej S.
The anisotropic mass transport issues inside a fuel cell membrane have been studied in this thesis using computer modelling. The polymer electrolyte membrane (PEM) conductivity of a PEM fuel cell (PEMFC) depends on the hydration state of the hydrophilic charged sites distributed in the pores of the membrane. Water humidification of these charged sites is crucial for sustaining the membrane conductivity and reducing concerning voltage losses of the cell. During the operation of a PEMFC, the transport of humidified inlet gases (fuel/oxidant) is influenced by external design factors such as flow field plate geometry of the gas circulating channels. As a result, there arises a distribution in the mass transport of water inside the membrane electrode assembly. A two-dimensional, cross-the-channel, fuel cell membrane layer mass transport model, developed in this work, helps the study of the impact of factors causing the distribution in the membrane ionic conductivity on ohmic losses.The governing equations of the membrane mathematical model stem from the multicomponent framework of concentrated solution theory. All mass transport driving forces within the vapour and/or liquid equilibrated phases have been accounted in this research. A computational model, based on the finite control volume method, has been implemented using a line-by-line approach for solving the dependent variables of the mass transport equations in the two-dimensional membrane domain. The required boundary conditions for performing the anisotropic mass transport analysis have been obtained from a detailed agglomerate model of the cathode catalyst layer available in the literature.The results obtained using boundary conditions with various flow field plate channel-land configurations revealed that the anisotropic water transport in the cathode half-cell severely affects the ohmic losses within the membrane. A partially humidified vapour equilibrated membrane simulation results show that a smaller channel-land ratio (1:1) sustains a better membrane performance compared to that with a larger one (2:1 or 4:1). Resistance calculations using the computer model revealed that ohmic losses across the membrane also depend on its physical parameters such as thickness. It was observed that the resistance offered by a thinner membrane towards vapour phase mass transport is comparatively lower than that offered by a thicker membrane. A further analysis accounting the practical aspects such as membrane swelling constraints, imposed by design limitations of a fuel cell, revealed that the membrane water content and ionic conductivity are altered with an increase in the compression constraint effects acting upon a free swelling membrane.
2D3V Particle-in-cell simulations of Electron Cyclotron Drift Instability and anomalous electron transport in ExB plasmas
(2021-09-17) Jimenez Jimenez, Marilyn; Bradley, Michael; Xiao, Chijin; Tse, John; Shevyakov, Alexey
This thesis is devoted to nonlinear physics of plasmas investigated with kinetic modeling. The emphasis is on the characterization of waves, instabilities, and anomalous electron transport. The main topic is related to partially magnetized plasmas immersed in crossed ExB fields with magnetized electrons and unmagnetized ions. Such plasmas are abundant in many applications such as Hall thrusters devices for space propulsion and material processing. The nonlinear evolution of the Electron Cyclotron Drift Instability (ECDI) driven by the electron ExB drift in partially magnetized plasmas and anomalous electron transport in two dimensions are studied using particle-in-cell (PIC) simulations. PIC simulations were performed for the parameters typical of the Hall-effect thruster in two-dimensional azimuthal-radial geometry to investigate the role of the boundaries conditions, electric and magnetic field magnitudes, sheath losses and finite-length on the mode development and anomalous electron current. The turbulence and the induced anomalous electron current are studied. Nature of the anomalous current and contribution of different wavelength are investigated. It is shown that the magnitude of the anomalous current can be explained as a ExB drift of magnetized electrons in fluctuating fields. The same PIC code was used for a benchmark project in simulations of a similar radial-azimuthal configuration of a Hall thruster. Seven different groups using independently developed codes were able to capture the same physics, both for ECDI and Modified Two-Stream Instability (MTSI) modes. An additional study related to the role of noise in kinetic plasma simulations is presented. It confirmed that statistical particle noise could distort some Buneman-type instabilities to be identified in the linear regime.
3-D ELECTROMAGNETIC FIELD SIMULATOR BASED DESIGN OF MULTILAYER MICROWAVE FILTERS
(2001) Chen, Lin; Pramanick, Protap; Dodds, David
Over the past decade, the explosive growth in wireless and mobile communication systems has generated a significant market for lightweight, ultra small filters that are amenable to mass manufacture without tuning. In this thesis, an inductively coupled multilayer resonator structure using lumped elements is proposed and applied to the design of bandpass filters using low-temperature cofired ceramic (LTCC). The design is based on the M.Dishal's method with a modern electromagnetic (EM) field simulator, which employs full-wave spectral domain Galerkin method of moments. The design procedure is described and design examples are given to demonstrate the features of the proposed coupling structure. A. Morini's method is then used to successfully design a multilayer diplexer that is extremely useful in wireless communication application. A two-pole LTCC multilayer filter is simulated and successfully built. Good experimental result is obtained. This is the first time that design curves are presented for inductively coupled multilayer ceramic (MLC) filters. This thesis also demonstrates the generality of the method for the design of multilayer bandpass filters and diplexers.
3D bioprinted hydrogel scaffolds laden with Schwann cells for use as nerve repair conduits
(2015-06-25) Rajaram, Ajay; Chen, Daniel; Schreyer, David; Hedayat, Assem; Zhang, Chris; Wu, FangXiang; Krone, Patrick
The goal of nerve tissue engineering is to promote and guide axon growth across a site of nerve injury without misdirection. Bioengineered tissue scaffolds have been shown to be promising for the regeneration of damaged peripheral nerves. Schwann cells play a pivotal role following nerve injury by forming aligned “bands of Büngner” that promote and guide axon regeneration into the distal nerve segment. The incorporation of living Schwann cells into various hydrogels has therefore been urged during the fabrication of tissue engineered nerve scaffolds. The aim of this research is to characterize biomaterials suitable for 3D bioplotting of nerve repair scaffolds. Here a novel technique of scaffold fabrication has been optimized to print alginate-based three-dimensional tissue scaffolds containing hyaluronic acid and living Schwann cells. Alginate/hyaluronic acid scaffolds were successfully fabricated with good printability and cell viability. Addition of the polycation polyethyleneimine (PEI) during the fabrication process stabilized the structure of alginate through the formation of a polyelectrolyte complex and had a significant influence on the degree of swelling, degradation rate, mechanical property, and release kinetics of incorporated protein within the scaffolds. A preliminary in vivo study showed the feasibility of implanting 3D printed alginate/hyaluronic acid scaffolds as nerve conduits in Sprague-Dawley (SD) rats with resected sciatic nerves. However alginate/hyaluronic acid scaffolds were found to be unsuitable for axonal regeneration. Further in vitro culture of Schwann cells was performed in collagen type-I, fibrin, fibrin/hyaluronic acid, and their combination with alginate. It was found that Schwann cells had more favorable cell morphology in fibrin/hyaluronic acid or collagen without alginate. Schwann cell proliferation and alignment were better in fibrin/hyaluronic acid. Therefore fibrin/hyaluronic acid is more ideal than most other hydrogel formulations for use in the bioprinting of nerve repair tissue engineering scaffolds, which incorporate cellular elements. As Schwann cells also align along the long axis of the printed fibrin/hyaluronic acid strands, 3D bioprinting of multiple layers of crosslinked fibrin strands can be used to fabricate a nerve conduit mimicking the bands of Büngner.
3D Bioprinted Respiratory Tissue Scaffolds for Disease Modelling Applications
(2024-07-02) Zimmerling, Amanda; Chen, Xiongbiao; Zhou, Yan; Zhang, Chris; Montgomery, Julia; Zhu, Ning; Dhar, Neeraj; Huang, Yong; Gerdts, Volker
Respiratory tissue engineering (RTE) aims to develop functional tissue constructs for regenerative or modelling applications by using engineering approaches. Among these approaches, the recently emerging technique of bioprinting is promising as it allows for the repeatable creation of hierarchical cell-containing structures, thus providing the ability to create functional tissue constructs/ models. However, there are still challenges in the use of this approach in RTE, primarily related to generating physiologically relevant constructs that recapitulate the complexity of native tissues. Aspects including biomaterial selection, incorporating accurate biomechanical stimuli, and providing natural biochemical signals are all different facets requiring consideration in increasing the physiological relevance of bioprinted respiratory tissues. Based on the promise of RTE, this thesis aims at developing novel in vitro respiratory tissue constructs by means of bioprinting. To address research issues in the field of RTE, four specific objectives are set in this thesis including, (1) synthesis and characterization of an optimal bioink, (2) incorporation of biomechanical stimuli mimicking the native respiratory environment, (3) incorporation of biochemical stimuli through use of a nanoparticle-controlled release system, and (4) proof of concept application of the developed constructs in disease modelling. Objective (1) involves the investigation and synthesis of bioinks from hydrogels and characterization of the bioinks in terms of mechanical properties, printability, and biocompatibility. Alginate was selected as the base material due to its lack of biotoxicity and its ability to undergo ionic cross-linking, which allows for a high degree of printability; however, alginate expresses negligible cell-adhesion motifs. As collagen type I is the primary protein found throughout the connective tissue of the respiratory tract, its addition increases biocompatibility and cell adhesion. After synthesis, rheological characterization was used to inform selection of printing parameters and printability was assessed to ensure consistent structures that closely recapitulated the design could be created. Bulk compression testing was carried out to determine the compressive modulus, while tensile testing of printed scaffolds was used for determination of the 3D printed lattice properties. These mechanical properties were compared to that of native respiratory tissues to determine similitude. Finally, human pulmonary fibroblast proliferation and viability within the materials was assessed to ensure biocompatibility. The cumulation of all of these results was then used to select the most promising alginate/collagen biomaterial for further use in creation of a respiratory tissue construct. Work then continued in Objectives (2) and (3) to increase the physiological relevance of the engineered construct through two different pathways. First, a bioreactor mimicking the pressure changes and airflow conditions of the human lung was developed and tested to determine the effect that biomechanical stimulus had on cell growth within the construct. Conditions recapitulating shallow, normal, and heavy breathing were tested to determine the effect on degradation, tensile properties, and human pulmonary fibroblast and bronchial epithelial cell proliferation and viability. These experiments provided insight into the influence of mechanical stimulus on cell growth and ECM production, with normal breathing conditions leading to an increase in cell proliferation. Second, a nanoparticle system for controlled release of growth factor was developed and tested to determine the effect of including relevant biochemical stimulus had on cell development within the bioprinted construct. For investigation into biochemical stimulus, a chitosan-coated alginate nanoparticle system was synthesized using an emulsion technique. These particles were loaded with growth factor aimed at stimulating epithelial growth. Initially, release kinetics of the particle system were tested comparing coated/uncoated and static/dynamic conditions. Rheology and printability of the bioink containing the loaded particles was tested along with tensile properties of the printed scaffolds. Finally, the bioactivity of the loaded nanoparticles was assessed to determine the functionality of the controlled release system. Although cell proliferation appeared unaffected, confocal imaging demonstrated an increase in the formation of an epithelial barrier layer. Finally, in Objectives (4) the application of the designed constructs, including both biomechanical and biochemical stimulus, in disease modelling was then investigated. The bioink used was varied slightly through the addition of gelatin and characterized accordingly in terms of rheology, mechanical properties, printability, and biological properties. Following this, structures containing human pulmonary fibroblasts and monocytes were printed before seeding with human bronchial epithelial cells. These structures were cultured at an air-liquid interface before being infected with an influenza A virus. Cell viability, metabolism, and chemokine release were measured to determine the ability of these constructs to function as a disease model. This thesis presents comprehensive work on the creation of bioprinted respiratory tissue scaffolds for disease modelling applications. This work may pave the way to improving disease modelling and therapeutic screening pathways by providing a humanized intermediary between 2D and animal models.
3D Bioprinting Tissue Scaffolds with Living Cells for Tissue Engineering Applications
(2018-04-24) Ning, Liqun 1988-; Wiens, Travis; Noble, Scott; Wu, Fangxiang; Chen, Li
In tissue engineering, tissue scaffolds are used as temporary supports to promote regeneration of dysfunctional tissues. Of the available strategies, scaffolds produced from hydrogels and living cells show the great potential for their enhanced biological properties. To produce such scaffolds, three-dimensional (3D) bioprinting has evolved and is showing promise as a fabrication technique. However, its applications for fabricating customized hydrogel scaffolds containing living cells is still in its infancy. The major challenge with this approach is to print scaffolds while preserving cell viability and functionality as well as ensuring the structural integrity of the scaffold. To overcome this challenge, the present thesis aims to investigate the influences of hydrogel properties and the bioprinting process on cell viability and functionality, while also ensuing structural integrity, and on this basis, to develop bioprinting processes to produce tissue scaffolds with living cells for potential tissue engineering applications. This thesis first examined the influence of the mechanical properties of hydrogel on cell viability and functionality, utilizing alginate hydrogels and Schwann cells (the major glial cells of peripheral nervous system). Due to its poor cell adhesion, the alginate hydrogel was modified in this study with cell-adhesion supplements, including fibronectin, poly-l-lysine (PLL), and RGD (Arg-Gly-Asp) peptides. The RGD-modified alginate substrates were prepared with varying alginate concentrations in order to alter the mechanical properties of hydrogels, which were then seeded and encapsulated with Schwann cells. Cell viability and functionality, including proliferation, morphology, and expression of the extracellular matrix protein, were examined and correlated to the hydrogel mechanical properties. The results demonstrate that the viability and functionality of Schwann cells within alginate-based hydrogel vary with hydrogel mechanical properties, thus highlighting the importance of regulating the mechanical properties of hydrogel for improved cell viability and functionality in scaffold bioprinting. During the bioprinting process, cells are subject to process-induced forces, such as shear and extensional stresses, which can result in cell damage and therefore loss of cell function and even cell death. A method was developed to study the cell damage introduced by the shear and extensional stresses in the bioprinting process. A plate-and-cone rheometer was adopted to examine the effect of shear stress on cell damage. In these experiments, the relationship of cell damage to the shear stress was examined and quantified, which was then applied to identify the cell damage attributed to shear stress in bioprinting. On this basis, the damage to cells caused by extensional stress was inferred from the difference between the total cell damage occurring during the bioprinting process and the cell damage attributed to shear stress. This developed method allowed a relationship to be established between cell damage and both shear and extensional stresses during bioprinting. The experiments on this method provide insight into both the cell damage that occurs during bioprinting and the effect on cell viability and proliferative ability thereafter, which can be used to optimize the bioprinting process so as to preserve cell functionality. Based on the previous investigations, bioprinting processes were developed to fabricate tissue scaffolds containing Schwann cells for potential applications in nerve tissue engineering. Composite hydrogels consisting of alginate, fibrin, hyaluronic acid, and RGD peptide were prepared, and their hydrogel microstructures, mechanical stiffness after gelation, and capability to support the Schwann cell spreading were examined for identifying appropriate composite hydrogel for bioprinting processes. The flow behavior of composite hydrogel solutions and bioprinting process parameters (e.g., dispensing pressure, dispensing head speed, crosslinking process) were then examined with regard to their influence on the structure of the printed scaffolds and on this basis, bioprinting process were developed to fabricate scaffolds with Schwann cells. The functionality of Schwann cells within the printed scaffolds were assessed in terms of cell viability, proliferation, morphology, orientation, and protein expression, demonstrating that the printed scaffolds have potential for nerve tissue engineering applications. This thesis presents a comprehensive study on the bioprinting of scaffolds with living cells. The method developed and the study results will pave the way to fabricate scaffolds with living cells for more tissue engineering applications.
3D follicle segmentation in ultrasound image volumes of ex-situ bovine ovaries
(2008) Lu, Qian; Eramian, Mark G.; Singh, Jaswant; Pierson, Roger A.; Mould, David; Chen, X. B. (Daniel); Adams, Gregg P.
Conventional ultrasonographic examination of the bovine ovary is based on a sequence of two-dimensional (2D) cross-section images. Day-to-day estimation of the number, size, shape and position of the ovarian follicles is one of the most important aspects of ovarian research. Computer-assisted follicle segmentation of ovarian volume can relieve physicians from the tedious manual detection of follicles, provide objective assessment of spatial relationships between the ovarian structures and therefore has the potential to improve accuracy. Modern segmentation procedures are performed on 2D images and the three-dimensional (3D) visualization of follicles is obtained from the reconstruction of a sequence of 2D segmented follicles. The objective of this study was to develop a semi-automatic 3D follicle segmentation method based on seeded region growing. The 3D datasets were acquired from a sequence of 2D ultrasound images and the ovarian structures were segmented from the reconstructed ovarian volume in a single step. A “seed” is placed manually in each follicle and the growth of the seed is controlled by the algorithm using a combination of average grey-level, standard deviation of the intensity, newly-developed volumetric comparison test and a termination criterion. One important contribution of this algorithm is that it overcomes the boundary leakage problem of follicles of conventional 2D segmentation procedures. The results were validated against the aspiration volume of follicles, the manually detected follicles by an expert and an existing algorithm.We anticipate that this algorithm will enhance follicular assessment based on current ultrasound techniques in cases when large numbers of follicles (e.g. ovarian superstimulation) obviate accurate counting and size measurement.
3D Printed Polycaprolactone/Nano-Hydroxyapatite Scaffolds for Bone Tissue Engineering In-Vitro
(2023-07-21) Yazdanpanah, Zahra; Chen, Xiongbiao (Daniel); Johnston, James D.; Cooper, David M. L.; Eames, Brian; Honaramooz, Ali; Hedayat, Assem; McWalter, Emily; Ahmadi, Ali
The abstract of this item is unavailable due to an embargo.
3D Printed Polycaprolactone/Nano-Hydroxyapatite Scaffolds for Bone Tissue Engineering In-Vitro
(2023-07-21) Yazdanpanah, Zahra; Chen, Xiongbiao (Daniel); Johnston, James D.; Cooper, David M. L.; Eames, Brian; Honaramooz, Ali; Hedayat, Assem; McWalter, Emily; Ahmadi, Ali
The abstract of this item is unavailable due to an embargo.
3D-IC Technology Characterization and Test Chip Design
(2013-08-20) Fan, Li; Chen, Li; Ko, Seok-Bum; Gokaraju, Ramakrishna; Wu, Fangxiang
With sub-micron silicon processing technology reaching under 30nm, it becomes more difficult for integrated circuits to achieve higher integration through the scaling down of the transistor size. Three-dimensional integrated circuit (3D-IC) technology stacks multiple dies together and connects them using through-silicon vias (TSVs). This is a low cost and highly efficient way to increase integration. TSVs and stacked dies are two major features of the 3D-IC technology. However, the stacked structures using TSV interconnects induce concerns in reliability such as TSV strain effect, heat problem, and TSV coupling at high frequency, etc. The reliability concerns need to be carefully addressed before 3D-IC technologies can be widely adopted by the industry. Many studies have been carried out in this field, but there has not been much significant work done for testing electrical, mechanical and thermal issues of the 3D-IC technology simultaneously on a single test chip. In this work, a test chip including various test structures was designed to study and analyze these issues in a 3D-IC technology. An accurate resistance and capacitance (RC) model of the TSV for low frequency design was developed, high frequency electrical performance of the TSVs was characterized, coupling between TSVs was modeled, and the stress effect and the heat dissipation method were analyzed in the 3D-IC technology. The TSV model could be added to the design kit for future 3D-IC design and other results could be used to improve the reliability of 3D-IC designs and optimize the performance.
A 50 MHz FMCW radar for the study of E-region coherent backscatter
(2006-06-19) Cooper, Joel; Hussey, Glenn C.
A 50~MHz E-region coherent backscatter radar was designed based on frequency modulated continuous wave (FMCW) radar techniques. This thesis presents the theory behind the FMCW technique and its implementation in a practical radar system. The system was designed and constructed at the University of Saskatchewan and was field tested at a radar site a few kilometres from the university. This thesis demonstrates that an FMCW radar is technically possible and functional as a research tool for E-region coherent backscatter studies. The primary goal of this research is to develop a better understanding of the plasma processes responsible for the radar echoes. FMCW techniques offer a compromise between the pulsed and continuous wave (CW) radar techniques, which have previously been used for E-region experiments. CW techniques provide excellent spectral measurements but are limited in their ability to determine range information. Pulsed techniques offer excellent range resolution but may be limited in their ability to make detailed high resolution Doppler measurements of E-region radar backscatter. The implementation of FMCW techniques provides a simple and effective method of simultaneously obtaining excellent Doppler and range measurements. The use of FMCW techniques is a novel approach to E-region coherent backscatter studies. Data analysis techniques were developed to extract the range and Doppler information from FMCW radar echoes. In the first few months of operation, the radar observed all four typical E-region radar signatures, Type I to Type IV, plus meteor trail echoes. Observations of each type of radar echo are presented, without interpretation, to illustrate the performance of the radar.
8-Hydroxyquinoline Copper Complexes in the Treatment of Neurodegenerative Disease
(2020-06-04) Summers, Kelly Lynn; Pickering, Ingrid J; George, Graham N; Urquhart, Stephen G; Paterson, Phyllis G; Foley, Stephen R; Price, Eric W; Scott, Robert WJ
Alzheimer’s disease (AD) is among the most prevalent and debilitating of over 40 different incurable human diseases associated with misfolding of one or more specific proteins or peptides, including the amyloid beta (Aβ) peptide. Despite the large volume of research that has focused on understanding AD mechanisms and identifying possible treatments, the field remains divided on what causes the disease, and therefore, what aspect(s) of disease pathology might be targeted to cure AD. One avenue of research hypothesizes that dyshomeostasis of brain metals such as copper, zinc, and iron is a key step in disease progression. To this end, metal chelation has been explored as a possible AD treatment. Promising results with 8-hydroxyquinoline (8HQ) based metal chelators, in both animals and humans, showed improvements in cognition and memory. Although these chelators have been postulated to restore brain metal ion homeostasis, their mechanism of action remains largely unknown. To better determine the mechanism(s) of action of 8HQ chelators, we investigated the solution structure of several 8HQ Cu(II) complexes using synchrotron X-ray absorption spectroscopy (XAS), along with the Cu(II)-binding site in the Aβ peptide, the major component of plaques in AD brains. We investigated metal ion distributions in single cells treated with 8HQs using synchrotron X-ray fluorescence imaging (XFI). We also developed a multimodal imaging technique to map the metal ion distribution (using XFI) and amyloid plaque distribution and composition in mammalian brain tissue using Fourier transform infrared (FTIR) mapping and Raman microscopy. Results from synchrotron techniques, and other more conventional techniques, suggest that the most promising 8HQ-based anti-AD drug, PBT2, binds Cu(II) differently than other 8HQs. These differences in Cu(II) binding appear to allow for different interactions with the Aβ peptide and to cause differential effects on single cells in culture. Our results from studies mapping AD mouse model brain sections show that areas of high aggregated protein (i.e. amyloid plaques), coincide with areas of high iron, copper, and zinc. Results from the multimodal imaging studies set the stage for future investigations into the metal ion redistribution and amyloid plaque degradation that has been proposed to occur following 8HQ treatment. Taken together, these results suggest that the Cu(II) coordination complexes formed with 8HQs in solution are likely to significantly impact their biological action.
A (S)hero's Journey: Paths to Re-writing Myths in the Star Wars Franchise
(2022-03-18) Giannelli, Federica; Banco, Lindsey; Roy, Wendy; Muri, Allison; Bath, Jon; Nelson, Brent
The Star Wars franchise shares a common storytelling thread with ancient myths, which have consistently centered on individuals experiencing life-changing journeys that influence their—and others’—world forever. How did Star Wars, now owned by the media conglomerate Disney, contribute to the process of making myths persistent throughout history? The key to this persistence seems to have been media adaptations: the franchise has re-written and re-interpreted tropes from previous mythologies and cultural products using the intertextual practices of contemporary visual media forms (film, TV series and animation). By using theories of intertextuality and adaptation, my dissertation analyzes how Star Wars re-writes and adapts two dominant mythologies in American culture—the Campbellian monomyth and the American Western mythos—in the new movies of the saga and in the series The Mandalorian and Forces of Destiny to explain the process of mythical re-writing in contemporary media. The aim is to advance the field of cultural studies by investigating how and why mythical representation has survived in Star Wars through the commodifying cultural mechanisms involved with re-distributing myths in contemporary media. I will also analyze the larger issues that mythical portrayals in Star Wars represent about American culture, especially their ability to depict American identity. My dissertation sheds light on how mythical storytelling in the new Star Wars movies, The Mandalorian and Forces of Destiny helps disrupt old dominant American ideologies of male- and white-centred heroic models to offer diverse representations of gender and ethnicity. My analysis shows that despite contradictions the new Star Wars hints at positive changes in the representation of American identity. This change signifies that the adaptable polysemic nature of myths—their ability to incorporate new meanings—is key to this process of ideological shifting. Also, my analysis provides evidence that this process of mythical revival becomes possible by adopting, as in Disney’s case, cultural production mechanisms that center around media technologies and commercialized products. Disney’s commodification results in turning myths into materialistic possessions for contemporary audiences to interact with, as my analysis of the Star Wars “Princesses” dolls and the “Baby Yoda” puppet suggests.

Browse

Browsing Electronic Theses and Dissertations by Title

Results Per Page

Sort Options