Physical Sciences and Mathematics Commons^™

Fragmentation And Wake Formation In Faint Meteors: Implications For The Structure And Ablation Of Small Meteoroids, Edward Stokan

Electronic Thesis and Dissertation Repository

Meteors with peak magnitudes fainter than +2 are typically called faint meteors, resulting from the atmospheric entry and ablation of meteoroids less massive than 10^-4 kg. The processes of luminous wake formation and fragmentation, which occur during ablation, are poorly understood for faint meteors, and are important constraints for models of meteoroid structure. The goal of this work is to improve understanding of these processes through analysis of high-resolution intensified video observations, and creation of a detailed meteoroid ablation model.

In the first part of this work, thirty faint meteors observed with the Canadian Automated Meteor Observatory (CAMO) are …

Kelvin Probe Force Microscopy On Graphene Thin Films For Solar Cell And Biosensing Applications, Faranak Sharifi

Electronic Thesis and Dissertation Repository

Graphene, a one atom thick planer sheet of carbon atoms, has attracted much attention in scientific and technological communities due to its remarkable electronic and physical properties. Graphene has been widely studied as an alternative to transparent conducting Indium Tin Oxide (ITO) electrodes in organic photovoltaics fabrication. Graphene platforms have also attracted interest in biological applications. However, large area graphene films are not yet widely commercialized because the fabrication techniques needed to prepare high quality graphene are expensive and non-scalable. More importantly, most of the low cost fabrication techniques require using toxic materials, which are not biocompatible for using graphene …

Organic Solar Cells: Electrodes, Performance Enhancement And Degradation Mechanisms, Reginald J. Bauld

Electronic Thesis and Dissertation Repository

In this thesis I focus on a number of aspects associated with the fabrication and characterization of organic photovoltaics. Specifically, my work focuses on evaluating solution processed graphene electrodes for use in organic photovoltaics, improving the performance of indium tin oxide transparent contacts by coating them with Au nanoparticles, and understanding the degradation pathways of Poly(3-hexylthiophene-2,5-diyl): Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) organic solar cells. In my work on graphene electrodes for organic solar cells I worked out a relationship between the sheet resistance and the film transmittance that is useful to optimize such electrodes. Investigation of organic solar cell degradation …

Gravity Wave Spectra Morphology In The Arctic And Non-Arctic Lower Atmosphere, Melanie C. Wright

Electronic Thesis and Dissertation Repository

The spectral analysis of data from three VHF radars (one high-Arctic and two mid-latitudes) show support for the universal spectrum theory for gravity waves in the lower atmosphere (altitudes of 2.0-11.0 km), provided that the impact of the off-vertical beam and noise are taken into consideration. This analysis also reveals that local gravity wave generation is of secondary importance, but still significant for determining the spectra.

A total of eight spectral methods were considered and scrutinized for the purposes of determining gravity wave spectra from VHF radar data. A definition for the “best” method was given and examined. The method …

Extending And Merging The Purple Crow Lidar Temperature Rayleigh And Vibrational Raman Climatologies, Ali Jalali

Electronic Thesis and Dissertation Repository

Rayleigh and Raman scatter measurements from The University ofWestern Ontario Purple Crow Lidar (PCL) have been used to develop temperature climatologies for the stratosphere, mesosphere, and thermosphere using data from 1994 to 2013 (Rayleigh system) and from 1999 to 2013 (vibrational Raman system). Temperature retrievals from Rayleigh-scattering lidar measurements have been performed using the methods by Hauchecorne and Chanin (1980; henceforth HC) and Khanna et al. (2012). Argall and Sica (2007) used the HC method to compute a climatology of the PCL measurements from 1994 to 2004 for 35 to 110 km, while Iserhienrhien et al. (2013) applied the same …

Defect-Related Magnetic And Electronic Properties Of Graphene, Arash Akbari-Sharbaf

Electronic Thesis and Dissertation Repository

A fundamental study of the electronic and magnetic properties of graphene modified by defects is presented. This work includes both theoretical and experimental investigations of graphene, graphene-metal composites and related structures, together with edge effects. The theoretical model employed for the description of p-electrons in graphene is based on the tight-binding Hamiltonian. On the experimental side we place special emphasis on the electron spin resonance technique (ESR).

After describing the theoretical and experimental methods, we first investigate the origin of paramagnetism in graphene nanoribbons (GNRs) using a combination of ESR and other characterisation techniques, corroborated by a theoretical model. …

Advances In Image Acquisition And Filtering For Mri Neuroimaging At 7 Tesla, Andrew T. Curtis

Electronic Thesis and Dissertation Repository

Performing magnetic resonance imaging at high magnetic field strength promises many improvements over low fields that are of direct benefit in functional neuroimaging. This includes the possibility of improved signal-to-noise levels, and increased BOLD functional contrast and spatial specificity. However, human MRI at 7T and above suffers from unique engineering challenges that limit the achievable gains. In this thesis, three technological developments are introduced, all of which address separate issues associated with functional magnetic resonance neuroimaging at very high magnetic field strengths.

First, the image homogeneity problem is addressed by investigating methods of RF shimming — modifying the excitation portion …

Plasmonic Optical Sensors: Performance Analysis And Engineering Towards Biosensing, Peipei Jia

Electronic Thesis and Dissertation Repository

Surface plasmon resonance (SPR) sensing for quantitative analysis of chemical reactions and biological interactions has become one of the most promising applications of plasmonics. This thesis focuses on performance analysis for plasmonic sensors and implementation of plamonic optical sensors with novel nanofabrication techniques.

A universal performance analysis model is established for general two-dimensional plasmonic sensors. This model is based on the fundamental facts of surface plasmon theory. The sensitivity only depends on excitation light wavelength as well as dielectric properties of metal and dielectrics. The expression involves no structure-specified parameters, which validates this formula in broad cases of periodic, quasiperiodic …

A Non-Contrast Magnetic Resonance Imaging Technique To Assess Blood-Brain Barrier Permeability, Harini Pandithasekera

Electronic Thesis and Dissertation Repository

The Blood-brain barrier (BBB) regulates the entry of compounds between the blood and the brain, thus plays an important role in brain homeostasis. Studies indicate in disease states such as Alzheimer’s the BBB integrity is compromised. The motive of this project is to investigate the sensitivity of the diffusion-weighted arterial spin labeling (DW-ASL) technique to detect water exchange. Testing the sensitivity requires a reliable method of opening the barrier at specific locations of the brain. Here, a unique technology named focused ultrasound (FUS) has been used to mimic a compromised BBB environment.

A series of experiments were conducted in a …

The Electrochemistry Of Hydrogen Peroxide On Uranium Dioxide And The Modelling Of Used Nuclear Fuel Corrosion Under Permanent Disposal Conditions, Linda Wu

Electronic Thesis and Dissertation Repository

This thesis reports a series of investigations examining the corrosion process of used nuclear fuel under permanent disposal conditions. The motivation of the project is that the safety assessment of deep geological disposal of spent nuclear fuel requires a fundamental understanding of the processes controlling fuel corrosion which could lead to the release of radionuclides to the geosphere from a failed container.

One primary objective of this project was to develop a computational model in order to simulate fuel corrosion under the disposal conditions. A series of simulations based on COMSOL were designed and developed to determine the influence of …

Quantum Optics Of Polaritonic Nanocomposites, Chris Racknor

Electronic Thesis and Dissertation Repository

In this thesis, we study the quantum optical interaction in polaritonic nanocomposites. These systems are made by the combination of two or more micro- or nano-scale structures with complementary optical properties, such as polaritonic materials, excitonic materials, photonic crystals (PCs), quantum dots (QDs), waveguides, couplers, metal nanorods (MNRs), bionanoparticles. The nanocomposites systems studied included QDs doped within a polaritonic PC, an excitonic waveguide coupler, and a metamaterial waveguide. Also addressed are systems consisting of MNRs paired with biological labelling dye or QDs.

The application of a strain field, known as the acousto-optic effect, was found to control photon transmission in …

Resting State Functional Magnetic Resonance And Diffusion Tensor Imaging Of Hemiplegic Cerebral Palsy Patients Treated With Constraint-Induced Movement Therapy: Predictors And Clinically Correlated Evidence Of Neuroplasticity, Kathryn Y. Manning

Electronic Thesis and Dissertation Repository

Hemiplegic cerebral palsy is characterized by unilateral upper limb impairment and patients often compensate by performing most tasks with their unaffected arm. Constraint-induced movement therapy (CIMT) directly combats this learned non-use by casting the unaffected arm and forcing the patient to repetitively practice skills with the hemiplegic limb. Subjects with hemiplegic cerebral palsy were recruited from Holland Bloorview Kids Rehabilitation Hospital, Thames Valley Children’s Centre and McMaster Children’s Hospital. MRI acquisitions and clinical evaluations were collected at baseline, 1 and 6-months later. The case group participated in a CIMT camp after baseline evaluations and was compared to an untreated control …

I. Accurate 50-200 Kev Proton Stopping Cross Sections In Solids Ii. Lateral Growth Of Si Wires On Si (100) Substrate, Sergey Dedyulin

Electronic Thesis and Dissertation Repository

Medium energy ion scattering (MEIS) is used to determine the elemental depth profile in the first few hundred angstroms of a sample. The interpretation of MEIS spectra requires an accurate knowledge of the rate at which the ions lose their energy - the stopping cross section, ε. The rate of energy loss has been fairly well investigated, both experimentally and theoretically, in elemental and compound targets at high energies (E>400 keV/amu). However, in the medium ion energy range where stopping cross section typically has a maximum, experimental data are scarce while most of the existing theories fail to give …

A Molecular Simulation Study On Micelle Fragmentation And Wetting In Nano-Confined Channels, Mona Habibi

Electronic Thesis and Dissertation Repository

We performed coarse-grained molecular-dynamics (MD) simulations to study the structural and dynamical properties of surfactant micelles in equilibrium and under Poiseuille-like flow in a nano-confined geometry. We used the MARTINI force-field to model the interactions between water molecules, counter-ions, and sodium dodecyl sulfate (SDS) surfactants. SDS surfactant was chosen as the standard model because of its potential application in drug delivery systems. First, we focused on the self-assembly of SDS in equilibrium. To form stable spherical mi- celles, we ran simulations in the isothermal-isobaric ensemble (NPT) on a system of free SDS surfactants, counter-ions and water molecules. We studied the …

Surface Plasmon Resonance Sensing Properties Of A 3d Nanostructure Consisting Of Aligned Nanohole And Nanocone Arrays, Mohamadreza Najiminaini, Erden Ertorer, Bozena Kaminska, Silvia Mittler, Jeffrey J.L. Carson

Physics and Astronomy Publications

Molecular surface plasmon resonance (SPR) sensing is one of the most common applications of an array of periodic nanoholes in a metal film. However, metallic nanohole arrays (NHAs) with low-hole count have lower resolution and SPR sensing performance compared to NHAs with high-hole count. In this paper, we present a compact three-dimensional (3D) plasmonic nanostructure with extraordinary optical transmission properties benefiting from surface plasmon matching and enhanced localized surface plasmon coupling. The 3D nanostructure consisted of a gold film containing a NHA with an underlying cavity and a gold nanocone array (NCA) at the bottom of the cavity. Each nanocone …