Physics Commons^™

Hyperpolarized 129xe Magnetic Resonance Imaging Of Radiation-Induced Lung Injury, Ozkan Doganay

Electronic Thesis and Dissertation Repository

Lung cancer is the largest contributor to cancer-related mortality worldwide. Only 20% of stage III non-small cell lung cancer patients survive after 5-years post radiation therapy (RT). Although RT is an important treatment modality for lung cancer, it is limited by Radiation-Induced Lung Injury (RILI). RILI develops in two phases: (i) the early phase (days-weeks) referred to radiation pneumonitis (RP), and (ii) the late phase (months). There is a strong interest in early detection of RP using imaging to improve outcomes of RT for lung cancer. This thesis describes a promising approach based on ¹²⁹Xe gas as a contrast …

High Resolution Tropospheric Studies With An Mst Type Radar, Marcial Garbanzo-Salas

Electronic Thesis and Dissertation Repository

Applications and results of a variety of studies carried out with the Costa Rican VHF profiler radar are included. This radar is unique because of the wide frequency bandwidth available (5 MHz). During the developing stages of the wind profiler radar new techniques of processing and radar engineering were used.

A thorough analysis of a data-dependent method (Capon's) commonly used in radar was carried out. This method is analyzed based on a reference established by Fourier theory. Disadvantages of using data-dependent methods with small filters were found. A small filter size will cause Capon's method to underestimate the number of …

Transmission Of Light In Nano-Hole Metamaterial, Shankaranandh Balakrishnan .

Electronic Thesis and Dissertation Repository

The interaction of light with metallic nano-hole array structures enable excitation of surface plasmon polaritons at any angle of incidence. Nano-hole array structure can transmit more radiation than incident light due to the presence of surface plasmon polaritons. This phenomenon has opened up possibilities for a wide range of applications such as Surface Plasmon Resonance sensing and Surface Enhanced Raman spectroscopy. In this thesis, quantum scattering theory and quantum density matrix method are employed to assess optical transmission of metallic nano-hole array structures. The scattering cross section spectrum is calculated for nano-hole array structures with different nano-hole radii and periodicities …

Charging Level And Deposition Of Droplets In Electrostatic Painting, Husam Osman

Electronic Thesis and Dissertation Repository

The process of electrostatic painting has become a very important method of coating in a wide range of industrial applications including those used in the automobile industry. The general principle of spray coating is to deposit liquid droplets or solid powder particles on coated targets having various shapes. The electrostatic coating process consists of three main stages: droplet formation and charging, transportation and deposition. The complication of this process is caused by various factors, such as the physical properties of the material to be used, the appropriate electrical and mechanical conditions and the target surface to be coated, which affects …

Secondary Electrohydrodynamic Flow Generated By Corona And Dielectric Barrier Discharges, Mohammadreza Ghazanchaei

Electronic Thesis and Dissertation Repository

One of the main goals of applied electrostatics engineering is to discover new perspectives in a wide range of research areas. Controlling the fluid media through electrostatic forces has brought new important scientific and industrial applications. Electric field induced flows, or electrohydrodynamics (EHD), have shown promise in the field of fluid dynamics. Although numerous EHD applications have been explored and extensively studied so far, most of the works are either experimental studies, which are not capable to explain the in depth physics of the phenomena, or detailed analytical studies, which are not time effective. The focus of this study is …

Dielectric Spectroscopy Of Polyvinyl Alcohol Hydrogels And Nanocomposites, Nuwansiri N.K. Getangama

Electronic Thesis and Dissertation Repository

Gels based on polyvinyl alcohol (PVA) can be formed by repeated freezing and thawing of a solution of the polymer. PVA cryogels have applications as biomaterials, including artificial tissue and drug delivery systems. The mechanical and electrical properties of polymeric materials can be changed significantly by adding a small amount of nanometer-sized particles. In this work, the dielectric properties of PVA solutions and gels were studied in the frequency range from 10 micro Hz to 1 MHz as a function of temperature, using a dielectric spectrometer. Comparison of the dielectric constant of a PVA solution to that of water indicates …

Characterization Of Cd93 Diffusion In Human Monocytes And Chinese Hamster Ovary Cells., Maria Goiko

Electronic Thesis and Dissertation Repository

The diffusion of CD93, a putative efferocytic receptor, was studied in the membrane of human monocytes and CHO cells using single particle tracking. We found that of CD93 molecules were confined in compartments consistent with actin corrals, while moved freely. Cage effect analysis showed short-lived caging of free CD93 and longer-lasting caging of confined CD93, with smaller corrals resulting in stronger caging. The motion of both free and confined CD93 was found to be consistent with a subdiffusive continuous time random walk, suggesting that CD93 diffusion is affected by several processes. We also sought to develop a total internal reflection …

Development Of A Small Animal Conformal Irradiator With Dual Energy X-Ray Computed Tomography Imaging For Kilovoltage Dosimetry, Michael D. Jensen

Electronic Thesis and Dissertation Repository

External beam radiotherapy has become technically sophisticated with image guided radiation therapy (IGRT) and intensity modulated radiation therapy (IMRT). These technologies allow for precise delivery of radiation to geometric targets in cancer patients. However, many questions remain on how to best define targets based on biological information, such as functional imaging, and how to combine radiation with other cancer therapies. To help answer these questions, small animal preclinical studies are needed to generate data to inform clinical trials. However, the precise radiation delivery capabilities of IGRT and IMRT have not been available in the preclinical labs. To enable translational experiments …

Studies Of Periodic And Quasiperiodic Gold Nanohole Arrays And Their Applications, Zhaoliang Yang

Electronic Thesis and Dissertation Repository

Wavelength to refractive index sensitivity and resonance wavelength position are two very important performance characteristics for nanohole array based surface plasmon resonance sensors while these characteristics are mostly researched on periodic nanohole arrays, instead of quasiperiodic nanohole arrays. This thesis deduces theoretical equations about the wavelength to refractive index sensitivity and resonance wavelength position of quasiperiodic nanohole arrays. Theoretical analysis shows that wavelength to refractive index sensitivity is not associated with geometry pattern, hole size or pitch but with the wavelength. A novel surface plasmon resonance platform is built by transferring gold films patterned with quasiperiodic nanohole arrays to the …

Ion Beam Modification Of Strontium Titanate And Highly Oriented Pyrolytic Graphite, Olga Lobacheva

Electronic Thesis and Dissertation Repository

Doping and structural modification affects such important characteristics as conductivity, catalytic activity, luminescent and magnetic properties of modern materials. Ion beam implantation is a conventional doping method which combines a low processing temperature with convenient control of concentration and distribution of dopant and irradiation damage. In this study, the ion beam implantation method was used to modify strontium titanate (STO) and highly oriented pyrolytic graphite (HOPG). Both materials have immense potential for applications in different areas of modern technology, including gas sensing, catalysis, electronics and spintronics. Fe-implanted STO and N- and O-implanted HOPG were examined with complementary experimental techniques, including …

Stellar Spectroscopy: New Methods And Insights, Sanaz S. Golriz

Electronic Thesis and Dissertation Repository

The study of the chemical evolution of stars is of crucial importance since they play a major role in the enrichment of the chemistry of the universe. Throughout their lifetime, stars undergo several processes that can alter their chemistry. Gradually, the nucleosynthesis products from the interior of the star are radiatively and convectively levitated and mixed with the upper layers of the atmosphere. In the later stages of their evolution, low to intermediate mass stars (0.8-8.0~M☉) eject a significant fraction of these nucleosynthesis products, resulting in a circumstellar envelope of gas and dust around the central star with a very …

A Study Of Photon Trapping And The Ac Stark Effect In Photonic Crystals And Dispersive Materials, Iftekharul Haque

Electronic Thesis and Dissertation Repository

In this thesis, we study light-matter interaction in the contexts of coherent population trapping (CPT) and the ac Stark effect in nanoparticles embedded (doped) in two important classes of reservoirs -- photonic crystals and dispersive materials. These materials have gaps in their energy spectra and are studied widely due to their unusual optical properties and potential for novel applications. We consider that the reservoirs are doped with an ensemble of five-level nanoparticles, each with a single Λ core (consisting of a lower doublet and an upper energy level), which interact with both the host reservoir and external radiation fields. We …

Edge States And Quantum Hall Phases In Graphene, Pavlo Piatkovskyi

Electronic Thesis and Dissertation Repository

The focus of this thesis is the dynamical symmetry breaking in monolayer and bilayer graphene in a magnetic field and the edge excitations in these systems. Due to the spin and valley degrees of freedom, the Coulomb interaction in graphene can lead to various broken-symmetry quantum Hall phases. The transport properties of each phase are affected by the low-energy edge excitations, and understanding the edge state properties can be crucial for identifying the true nature of the ground state. We study edge states in biased bilayer graphene in a magnetic field within the four-band continuum model. The analysis is done …