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Articles 1 - 10 of 10
Full-Text Articles in Physics
Unusually Low Thermal Conductivity In The Argyrodite Ag8gete6 Attributed To Strong Anharmonicity, Dale Hitchcock
Unusually Low Thermal Conductivity In The Argyrodite Ag8gete6 Attributed To Strong Anharmonicity, Dale Hitchcock
All Dissertations
Arguably the main focus of thermoelectric materials research over the last decade has been the reduction of lattice thermal conductivity through nanostructuring. This approach has proved quite effective in many instances, but has several inherent drawbacks including not only the metastability of many of the nanostructures used, but also difficulty decoupling the effects on the thermal properties of materials from the effects on their electrical properties. Some more recent research has focused on reduced thermal conductivity in materials with strong anharmonicity. In these systems anharmonicty in the crystal structure, whose strength can be gauged by the so-called Gruneissen parameter leads …
Chasing Polys: Interdisciplinary Affinity And Its Connection To Physics Identity, Tyler Scott
Chasing Polys: Interdisciplinary Affinity And Its Connection To Physics Identity, Tyler Scott
All Dissertations
This research is based on two motivations that merge by means of the frameworks of interdisciplinary affinity and physics identity. First, a goal of education is to develop interdisciplinary abilities in students' thinking and work. But an often ignored factor is students interests and beliefs about being interdisciplinary. Thus, this work develops and uses a framework called interdisciplinary affinity. It encompasses students interests in making connections across disciplines and their beliefs about their abilities to make those connections. The second motivation of this research is to better understand how to engage more students with physics. Physics identity describes how a …
Majorana Fermions In Chiral Topological Superconductors, Eugen Florin Dumitrescu
Majorana Fermions In Chiral Topological Superconductors, Eugen Florin Dumitrescu
All Dissertations
Majorana fermions were first proposed in the context of high energy physics by Ettore Majorana in 1937, just before his mysterious disappearance. Now, over 70 years later, signatures of condensed matter ana-logues of Majorana fermions are finally appearing in low-dimensional superconductor-based heterostructures. In low-dimensional systems, these order parameter, defect-bound Majorana quasiparticles obey non-Abelian quantum statistics and can therefore be used as the building blocks of a topological quantum computer. In this thesis we will analyze the signatures associated with, and the robustness of, Majorana bound states in a variety of one-dimensional superconducting platforms. Our main result is the finding that …
Fast Fission Neutron Detection Using The Cherenkov Effect, Matthew Millard
Fast Fission Neutron Detection Using The Cherenkov Effect, Matthew Millard
All Theses
The Cherenkov effect in optically clear media of varying indices of refraction and composition was investigated for quantification of fast neutrons. The ultimate application of the proposed detection system is criticality monitoring. The optically clear medium, composed of select target nuclei, was coupled to a photomultiplier tube. Neutron reaction products of the target nuclei contained within the optical medium emit beta particles and gamma rays that produce Cherenkov photons within the medium which can be detected. Assessed media include quartz (SiO2), sapphire (Al2O3), spinel (MgAl2O4), and zinc sulfide (ZnS), which were irradiated with un-moderated 252Cf. Monte Carlo N-Particle (MCNP) code …
Mechanical Properties Of Low Dimensional Materials, Deepika Saini
Mechanical Properties Of Low Dimensional Materials, Deepika Saini
All Dissertations
Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This Dissertation focuses on developing techniques for accurate determination of elastic …
Energy Loss Of Ions Implanted In Mos Dielectric Films, Radhey Shyam
Energy Loss Of Ions Implanted In Mos Dielectric Films, Radhey Shyam
All Dissertations
Energy loss measurements of ions in the low kinetic energy regime have been made on as-grown SiO2(170-190nm) targets. Singly charged Na+ ions with kinetic energies of 2-5 keV and highly charged ions Ar+Q (Q=4, 8 and 11) with a kinetic energy of 1 keV were used. Excitations produced by the ion energy loss in the oxides were captured by encapsulating the irradiated oxide under a top metallic contact. The resulting Metal-Oxide-Semiconductor (MOS) devices were probed with Capacitance-Voltage (C V) measurements and extracted the flatband voltages from the C-V curves. The C-V results for singly charged ion experiments reveal …
A Biophysical Understanding Of The Applications And Implications Of Nanomaterials, Nicholas Geitner
A Biophysical Understanding Of The Applications And Implications Of Nanomaterials, Nicholas Geitner
All Dissertations
The last few decades have seen an explosion in the study and application of nanomaterials that continues to grow at a dizzying pace. Despite exciting applications in nano-enabled electronics, materials, medicine, and environmental remediation, an understanding of the interactions of these materials with natural materials and systems and the resulting implications lags severely behind. The purpose of this Dissertation is to illuminate these interactions as well as develop novel environmental applications from a biophysical perspective. Following an introduction and literature review in Chapter 1, Chapters 2-4 will explore the application of dendritic polymers as novel and biocompatible oil dispersants for …
Protein Nano-Object Integrator: Generating Atomic-Style Objects For Use In Molecular Biophysics, Nicholas Smith
Protein Nano-Object Integrator: Generating Atomic-Style Objects For Use In Molecular Biophysics, Nicholas Smith
All Theses
As researchers obtain access to greater and greater amounts of computational power, focus has shifted towards modeling macroscopic objects while still maintaining atomic-level details. The Protein Nano-Object Integrator (ProNOI) presented here has been designed to provide a streamlined solution for creating and designing macro-scale objects with atomic-level details to be used in molecular simulations and tools. To accomplish this, two different interfaces were developed: a Protein Data Bank (PDB), PDB-focused interface for generating regularly-shaped three-dimensional atomic objects and a 2D image-based interface for tracing images with irregularly shaped objects and then extracting three-dimensional models from these images. Each interface is …
Fourth Moment Approximation Of Instrinsic Mode Lifetimes In Solids, Yang Gao
Fourth Moment Approximation Of Instrinsic Mode Lifetimes In Solids, Yang Gao
All Dissertations
A new method (second moment approximation method) of calculating mode lifetimes of materials has been proposed by Dickel and Daw [14, 15]. The method was tested on an anharmonic lattice model, and it shows consistency with results from using traditional method (molecular dy-namics with Green-Kubo [2]) at high temperatures, but deviates at low temperatures. Based on this method, we developed the fourth moment approximation method, and tested it on various models from 1D anharmonic chain to the FCC cube with Lennard-Jones potential. Calculations showed that the fourth moment approximation method provides a fast and reliable scheme to calculate mode lifetimes …
Multidimensional Simulations Of Non-Linear Cosmic Ray Production In Supernova Remnant Evolution, Joshua Wood
Multidimensional Simulations Of Non-Linear Cosmic Ray Production In Supernova Remnant Evolution, Joshua Wood
All Dissertations
When a high-mass star (& 4Msun) explodes at the end of its life, a supernova occurs, leaving its degenerate core and a fast-moving shell of matter, known as a supernova remnant (SNR). The SNR shell lasts for many thousands of years, generating emissions from low-frequency radio (~ 10-7 eV) up to γ-ray regime (~ 1015 eV). It is also believed that SNRs are the predominant source of galactic cosmic rays, accelerating a population of thermal ions, primarily protons, up to relativistic energies by means of the diffusive shock acceleration (DSA) mechanism. The small population of thermal (Boltzmann) particles, p ~ …