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Full-Text Articles in Physics

Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez Jan 2015

Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez

Open Access Theses & Dissertations

Cadmium Telluride is a material widely used in terrestrial thin film photovoltaic applications due to its nearly ideal band gap (~1.5 eV) and high absorption coefficient. Due to its low manufacturing cost, this technology has the potential to become a significant energy resource if higher energy conversion efficiencies are achieved. However, the module efficiencies (~14%) are still far from the theoretical maximum (~30%) for this material in a single junction configuration. The reason behind this low performance is attributed to the high number of defects that are present within the device materials. The physics behind the formation mechanisms of ...


The Meteorological Conditions Affecting The Propagation Of Respiratory Diseases, Rosette Maria Gonzalez Jan 2015

The Meteorological Conditions Affecting The Propagation Of Respiratory Diseases, Rosette Maria Gonzalez

Open Access Theses & Dissertations

Valley Fever, also known as Coccidioidomycosis, is endemic of the US Southwest. In 2012 this disease was the second most-reported disease in Arizona, according to the New Yorker January 2014 edition. The Paso Del Norte Region (PdN) is a semi-arid region with significant agricultural acreage and Valley Fever is known to be a threat in this region. It is our goal in this Thesis work to apply an existing PBL Height Program (e.g., Liu, et.al.) to the Paso Del Norte Region (PdN) to study the effect it has in the transmission of Valley Fever. Obtaining the PBLH as ...


Ac-Susceptibility And Epr Investigations Of Superspin Dynamics In Magnetite Nanoparticles, Alex D. Price Jan 2015

Ac-Susceptibility And Epr Investigations Of Superspin Dynamics In Magnetite Nanoparticles, Alex D. Price

Open Access Theses & Dissertations

In this investigation we use two complementary techniques to distinguish between superparamagnetic blocking (SPB) and superspin-glass (SSG) freezing phenomena in magnetite nanoparticles. While these manifestations of the superspin dynamics are fundamentally different, they have similar "signatures", especially in dc-magnetization experiments. Even if ac-susceptibility measurements are employed, careful use of mathematical models to analyze the data are needed to uncover which type of phenomena (SPB or SSG freezing) occurs within the material. Yet, by utilizing electron paramagnetic resonance (EPR) on a 10 nm Fe3O4 nano-powder as well as on a ferrofluid (based on the same nanoparticle ensemble) we found a very ...


Studying Cellular And Molecular Interaction With Two-Photon Fluorescence Microscopy, Arifur Rahaman Jan 2015

Studying Cellular And Molecular Interaction With Two-Photon Fluorescence Microscopy, Arifur Rahaman

Open Access Theses & Dissertations

Advances in microscopy and fluorescent probes provide new insight into studying cellular and molecular interactions. Two-photon fluorescence microscopy is one of the most important recent inventions in cellular and molecular study. This technology enables noninvasive study at cellular and molecular levels in three dimensions with submicrometer resolution. Two-photon excitation of fluorophores results from the simultaneous absorption of two photons. This excitation process has a number of unique advantages, such as reduced specimen photodamage and enhanced penetration depth. In this study, we used our two-photon microscope to observe predatorial behavior of fast moving bacterivorous marine organism Cafeteria roenbergensis and quantify Mycobacterium ...


Microscopic And Spectroscopic Analysis Of Cadmium Telluride, Jessica Goretty Salazar Jan 2015

Microscopic And Spectroscopic Analysis Of Cadmium Telluride, Jessica Goretty Salazar

Open Access Theses & Dissertations

Cadmium telluride (CdTe) remains one of the materials of interest in the fabrication of photovoltaic cells and infrared devices, mainly because of its suitable crystal structure as well as of its small, direct bandgap of 1.5 eV. Since development of such devices requires a high quality and low defect material, the goal of this study is to microscopically and spectroscopically examine not only crystallinity, but also the induced stress in the material due to the effect of substrate orientation. This information is valuable if optimization of sample growth conditions is envisioned. Prior to CdTe deposition by close-spaced sublimation (CSS ...


Effect Of Plastic Deformation Anisotropies On Shock-Induced Phase Transitions In Metallic Single Crystals, Punam Ghimire Jan 2015

Effect Of Plastic Deformation Anisotropies On Shock-Induced Phase Transitions In Metallic Single Crystals, Punam Ghimire

Open Access Theses & Dissertations

Most metals and alloys undergo plastic deformation at shear stresses and/or pressures in the Kbars regime. On the other hand, typical pressure-induced structural transitions, take place at much higher pressures, in the tens of GPa range. Surprisingly, there has not been to date, a systematic study on the role plastic deformation plays on the dynamics of defect-mediated phase transformations. The main purpose of this work was to investigate via atomistic simulations, the contribution of pre-existing defect densities on the kinetics of structural transformations under dynamic loading. We have carried out molecular dynamics simulations - including large-scale non-equilibrium molecular dynamics (NEMD ...


Ac-Susceptibility Investigations Of Superspin Blocking And Freezing In Interacting Magnetic Nanoparticle Ensembles, Joshua Logan Morris Jan 2015

Ac-Susceptibility Investigations Of Superspin Blocking And Freezing In Interacting Magnetic Nanoparticle Ensembles, Joshua Logan Morris

Open Access Theses & Dissertations

We have investigated the effect of dipolar interactions on the superspin blocking and freezing of 10 nm average size Fe3O4 magnetic nanoparticle ensembles. Our dynamic susceptibility data reveals a two-regime behavior of the blocking temperature, TB, upon diluting a Fe3O4/hexane magnetic nanoparticle fluid. As the nanoparticle volume ratio, Phi, is reduced from an as-prepared reference Phi = 1 to Phi = 1/96, the blocking temperature decreases from 46.1 K to 34.2 K, but higher values reenter upon further diluting the magnetic fluid to Phi = 1/384 (where TB = 42.5 K). We show that cooling below TB within ...


Computational Search For Novel Magnetic Clusters With Large Magnetic Anisotropy Energy, Nabil Md Rakinul Hoque Jan 2015

Computational Search For Novel Magnetic Clusters With Large Magnetic Anisotropy Energy, Nabil Md Rakinul Hoque

Open Access Theses & Dissertations

The clusters of transition metal atoms often show high spin moments but generally are reactive with the environment. Passivation of the surface atoms can lead to more stable clusters. We have explored one such avenue for passivation in this work. We picked the As@Ni12@As20 cluster which in the neutral state has a magnetic moment of 3 μB. We doped this cluster with various numbers of Mn atoms by substituting Ni atoms. The substitutional doping leads to spin moments located on the Mn atoms. The doping leads to symmetry breaking and as a consequence the number of structural isomers ...