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Ion-Induced Damage In Si: A Fundamental Study of Basic Mechanisms over a Wide Range of Implantation Conditions

Description: A new understanding of the damage formation mechanisms in Si is developed and investigated over an extended range of ion energy, dose, and irradiation temperature. A simple model for dealing with ion-induced damage is proposed, which is shown to be applicable over the range of implantation conditions. In particular the concept of defect "excesses" will be discussed. An excess exists in the lattice when there is a local surplus of one particular type of defect, such as an interstitial, over i… more
Date: May 2006
Creator: Roth, Elaine Grannan
Item Type: Refine your search to only Thesis or Dissertation
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Magnetotransport Properties of AlxIn1-xAsySb1-y/GaSb and Optical Properties of GaAs1-xSbx

Description: Multilayer structures of AlxIn1-xAsySb1-y/GaSb (0.37 £ x £ 0.43, 0.50 £ y £ 0.52), grown by molecular beam epitaxy on GaSb (100) substrates were characterized using variable temperature Hall and Shubnikov-de Haas techniques. For nominally undoped structures both p and n-type conductivity was observed. The mobilities obtained were lower than those predicted by an interpolation method using the binary alloys; therefore, a detailed analysis of mobility versus temperature data was performed to … more
Date: May 2003
Creator: Lukic- Zrnic, Reiko
Item Type: Refine your search to only Thesis or Dissertation

Characterization, Properties and Applications of Novel Nanostructured Hydrogels.

Description: The characterization, properties and applications of the novel nanostructured microgel (nanoparticle network and microgel crystal) composed of poly-N-isopropylacrylanmide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid(AA) have been investigated. For the novel nanostructured hydrogels with the two levels of structure: the primary network inside each individual particle and the secondary network of the crosslinked nanoparticles, the new shear modulus, drug release law from hydrog… more
Access: Restricted to the UNT Community Members at a UNT Libraries Location.
Date: December 2006
Creator: Tang, Shijun
Item Type: Refine your search to only Thesis or Dissertation

Carbon Nanotube/Microwave Interactions and Applications to Hydrogen Fuel Cells.

Description: One of the leading problems that will be carried into the 21st century is that of alternative fuels to get our planet away from the consumption of fossil fuels. There has been a growing interest in the use of nanotechnology to somehow aid in this progression. There are several unanswered questions in how to do this. It is known that carbon nanotubes will store hydrogen but it is unclear how to increase that storage capacity and how to remove this hydrogen fuel once stored. This document off… more
Access: Restricted to the UNT Community Members at a UNT Libraries Location.
Date: May 2004
Creator: Imholt, Timothy James
Item Type: Refine your search to only Thesis or Dissertation
open access

Perturbation of renewal processes

Description: Renewal theory began development in the early 1940s, as the need for it in the industrial engineering sub-discipline operations research had risen. In time, the theory found applications in many stochastic processes. In this thesis I investigated the effect of seasonal effects on Poisson and non-Poisson renewal processes in the form of perturbations. It was determined that the statistical analysis methods developed at UNT Center for Nonlinear Science can be used to detect the effects of seasona… more
Date: May 2008
Creator: Akin, Osman Caglar
Item Type: Refine your search to only Thesis or Dissertation
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Microscopic Foundations of Thermodynamics and Generalized Statistical Ensembles

Description: This dissertation aims at addressing two important theoretical questions which are still debated in the statistical mechanical community. The first question has to do with the outstanding problem of how to reconcile time-reversal asymmetric macroscopic laws with the time-reversal symmetric laws of microscopic dynamics. This problem is addressed by developing a novel mechanical approach inspired by the work of Helmholtz on monocyclic systems and the Heat Theorem, i.e., the Helmholtz Theorem. By … more
Date: May 2008
Creator: Campisi, Michele
Item Type: Refine your search to only Thesis or Dissertation
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Multifunctional Organic-Inorganic Hybrid Nanophotonic Devices

Description: The emergence of optical applications, such as lasers, fiber optics, and semiconductor based sources and detectors, has created a drive for smaller and more specialized devices. Nanophotonics is an emerging field of study that encompasses the disciplines of physics, engineering, chemistry, biology, applied sciences and biomedical technology. In particular, nanophotonics explores optical processes on a nanoscale. This dissertation presents nanophotonic applications that incorporate various fo… more
Date: May 2008
Creator: Garner, Brett William
Item Type: Refine your search to only Thesis or Dissertation
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Emergence of Complexity from Synchronization and Cooperation

Description: The dynamical origin of complexity is an object of intense debate and, up to moment of writing this manuscript, no unified approach exists as to how it should be properly addressed. This research work adopts the perspective of complexity as characterized by the emergence of non-Poisson renewal processes. In particular I introduce two new complex system models, namely the two-state stochastic clocks and the integrate-and-fire stochastic neurons, and investigate its coupled dynamics in diff… more
Date: May 2008
Creator: Geneston, Elvis L.
Item Type: Refine your search to only Thesis or Dissertation
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The Nonadditive Generalization of Klimontovich's S-Theorem for Open Systems and Boltzmann's Orthodes

Description: We show that the nonadditive open systems can be studied in a consistent manner by using a generalized version of S-theorem. This new generalized S-theorem can further be considered as an indication of self-organization in nonadditive open systems as prescribed by Haken. The nonadditive S-theorem is then illustrated by using the modified Van der Pol oscillator. Finally, Tsallis entropy as an equilibrium entropy is studied by using Boltzmann's method of orthodes. This part of dissertation shows … more
Date: August 2008
Creator: Bagci, Gokhan Baris
Item Type: Refine your search to only Thesis or Dissertation
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Oligonucleotide guanosine conjugated to gallium nitride nano-structures for photonics.

Description: In this work, I studied the hybrid system based on self-assembled guanosine crystal (SAGC) conjugated to wide-bandgap semiconductor gallium nitride (GaN). Guanosine is one of the four bases of DNA and has the lowest oxidation energy, which favors carrier transport. It also has large dipole moment. Guanosine molecules self-assemble to ribbon-like structure in confined space. GaN surface can have positive or negative polarity depending on whether the surface is Ga- or N-terminated. I studied… more
Date: August 2008
Creator: Li, Jianyou
Item Type: Refine your search to only Thesis or Dissertation
open access

Neutron Transmutation and Hydrogenation Study of Hg₁₋xCdxTe

Description: Anomalous Hall behavior of HgCdTe refers to a "double cross-over" feature of the Hall coefficient in p-type material, or a peak in the Hall mobility or Hall coefficient in n-type material. A magnetoconductivity tensor approach was utilized to identify presence of two electrons contributing to the conduction as well as transport properties of each electron in the material. The two electron model for the mobility shows that the anomalous Hall behavior results from the competition of two electron… more
Date: December 2007
Creator: Zhao, Wei
Item Type: Refine your search to only Thesis or Dissertation
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Exploration of hierarchical leadership and connectivity in neural networks in vitro.

Description: Living neural networks are capable of processing information much faster than a modern computer, despite running at significantly lower clock speeds. Therefore, understanding the mechanisms neural networks utilize is an issue of substantial importance. Neuronal interaction dynamics were studied using histiotypic networks growing on microelectrode arrays in vitro. Hierarchical relationships were explored using bursting (when many neurons fire in a short time frame) dynamics, pairwise neuronal a… more
Date: December 2008
Creator: Ham, Michael I.
Item Type: Refine your search to only Thesis or Dissertation
open access

Nonlinear UV Laser Build-up Cavity: An Efficient Design

Description: Using the concept of the build-up cavity for second harmonic generation to produce 243nm laser light, an innovative cavity is theoretically explored using a 15mm length CLBO crystal. In order to limit the losses of the cavity, the number of effective optical surfaces is kept to only four and the use of a MgF2 crystal is adopted to separate the harmonic and fundamental laser beam from each other. The cavity is shown to have an expected round trip loss of five tenths of a percent or better, resu… more
Date: May 2009
Creator: Rady, Nicholas Henry
Item Type: Refine your search to only Thesis or Dissertation
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Growth and Characterization of β-Iron Disilicide, β-Iron Silicon Germanide, and Osmium Silicides

Description: The semiconducting silicides offer significant potential for use in optoelectronic devices. Full implementation of the materials, however, requires the ability to tailor the energy gap and band structure to permit the synthesis of heterojunctions. One promising approach is to alloy the silicides with Ge. As part of an investigation into the synthesis of semiconducting silicide heterostructures, a series of β-Fe(Si1−xGex)2 epilayer samples, with nominal alloy content in the range 0 < x < 0.15, h… more
Date: August 2009
Creator: Cottier, Ryan James
Item Type: Refine your search to only Thesis or Dissertation
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EEG, Alpha Waves and Coherence

Description: This thesis addresses some theoretical issues generated by the results of recent analysis of EEG time series proving the brain dynamics are driven by abrupt changes making them depart from the ordinary Poisson condition. These changes are renewal, unpredictable and non-ergodic. We refer to them as crucial events. How is it possible that this form of randomness be compatible with the generation of waves, for instance alpha waves, whose observation seems to suggest the opposite view the brain is … more
Date: May 2010
Creator: Ascolani, Gianluca
Item Type: Refine your search to only Thesis or Dissertation
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A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure

Description: Spectroscopic measurements of the helium atom are performed to high precision using an atomic beam apparatus and electro-optic laser techniques. These measurements, in addition to serving as a test of helium theory, also provide a new determination of the fine structure constant &#945;. An apparatus was designed and built to overcome limitations encountered in a previous experiment. Not only did this allow an improved level of precision but also enabled new consistency checks, including an extr… more
Date: August 2010
Creator: Smiciklas, Marc
Item Type: Refine your search to only Thesis or Dissertation
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Thorium and Uranium M-shell X-ray Production Cross Sections for 0.4 – 4.0 MeV Protons, 0.4 - 6.0 MeV Helium Ions, 4.5 – 11.3 MeV Carbon Ions, and 4.5 – 13.5 MeV Oxygen Ions.

Description: The M-shell x-ray production cross section for thorium and uranium have been determined for protons of energy 0.4 - 4.0 MeV, helium ions of energy 0.4 - 6.0 MeV, carbon ions of energy 4.5 - 11.3 MeV and oxygen ions of energy 4.5 - 13.5 MeV. The total cross sections and the cross sections for individual x-ray peaks in the spectrum, consisting of the following transitions Mz (M4-N2, M5-N3, M4-N3), Ma (M5-N6,7), Mb (M4-N6, M5-O3, M4- O2), and Mg (M4-O3, M5-P3, M3-N4, M3-N5), were compared to the t… more
Date: May 2011
Creator: Phinney, Lucas C.
Item Type: Refine your search to only Thesis or Dissertation
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Ion Beam Synthesis of Carbon Assisted Nanosystems in Silicon Based Substrates

Description: The systematic study of the formation of &#946;-SiC formed by low energy carbon ion (C-)implantation into Si followed by high temperature annealing is presented. The research is performed to explore the optimal annealing conditions. The formation of crystalline &#946;-SiC is clearly observed in the sample annealed at 1100 °C for a period of 1 hr. Quantitative analysis is performed in the formation of &#946;-SiC by the process of implantation of different carbon ion fluences of 1×1017, 2×1017, 5… more
Date: May 2011
Creator: Poudel, Prakash Raj
Item Type: Refine your search to only Thesis or Dissertation
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A Positive Ion Source

Description: This paper describes the construction of a positive ion source of the electrodeless discharge type and may be divided into two main topis; (1) the radio frequency oscillator and power amplifier and associated power supply and (2) the ionization chamber.
Date: 1948
Creator: Hannah, Kenneth W.
Item Type: Refine your search to only Thesis or Dissertation
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Dipole Moments of Diphenyl Compounds with Conjugated Double Bonds

Description: This thesis is a continuation of a study of molecular moments begun by Joseph T. Fielder. In his paper he discussed the theory and the equipment necessary for such a study. It is the purpose of this paper to set forth modifications of his equipment, to present data obtained with this modified equipment, and to interpret this data.
Date: 1950
Creator: Spalding, Dan W.
Item Type: Refine your search to only Thesis or Dissertation
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