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Investigations of the R5(SixGe1-x)4 Intermetallic Compounds by X-Ray Resonant Magnetic Scattering

Description: The XRMS experiment on the Gd{sub 5}Ge{sub 4} system has shown that, below the Neel temperature, T{sub N} = 127 K, the magnetic unit cells is the same as the chemical unit cell. From azimuth scans and the Q dependence of the magnetic scattering, all three Gd sites in the structure were determined to be in the same magnetic space group Pnma. The magnetic moments are aligned along the c-axis and the c-components of the magnetic moments at the three different sites are equal. The ferromagnetic sla… more
Date: August 18, 2008
Creator: Tan, Lizhi
Partner: UNT Libraries Government Documents Department
open access

Search for Rare Multi-Pion Decays of the Tau Lepton Using the BABAR Detector

Description: A search for the decay of the {tau} lepton to rare multi-pion final states is performed using the BABAR detector at the PEP-II asymmetric-energy e+e- collider. The analysis uses 232 fb-1 of data at center-of-mass energies on or near the {Upsilon}(4S) resonance. In the search for the {tau}- {yields} 3{pi}-2{pi}+2{pi}{sup 0}{nu}{sub {tau}} decay, we observe 10 events with an expected background of 6.5{sup +2.0}{sub -1.4} events. In the absence of a signal, we calculate the decay branching ratio u… more
Date: September 18, 2007
Creator: Ter-Antonyan, Ruben
Partner: UNT Libraries Government Documents Department
open access

Structural and Electronic Investigations of Complex Intermetallic Compounds

Description: In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentr… more
Date: August 18, 2008
Creator: Ko, Hyunjin
Partner: UNT Libraries Government Documents Department
open access

Potential Applications of Microtesla Magnetic Resonance ImagingDetected Using a Superconducting Quantum Interference Device

Description: This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 {micro}T. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier … more
Date: May 18, 2006
Creator: Myers, Whittier R.
Partner: UNT Libraries Government Documents Department
open access

Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

Description: Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed… more
Date: August 18, 2008
Creator: Saetveit, Nathan Joe
Partner: UNT Libraries Government Documents Department
open access

Novel Bioplastics and biocomposites from Vegetable Oils

Description: Polymeric materials have been prevalent in our everyday lives for quite a long time. Most of today's polymeric materials are derived from nonrenewable petroleum-based feedstocks. Instabilities in the regions where petroleum is drilled, along with an increased demand in petroleum, have driven the price of crude oil to record high prices. This, in effect, increases the price of petroleum-based polymeric materials, which has caused a heightened awareness of renewable alternatives for polymeric fee… more
Date: August 18, 2008
Creator: Henna, Phillip H.
Partner: UNT Libraries Government Documents Department
open access

Measuring the Interestingness of Articles in a Limited User Environment Prospectus

Description: Search engines, such as Google, assign scores to news articles based on their relevancy to a query. However, not all relevant articles for the query may be interesting to a user. For example, if the article is old or yields little new information, the article would be uninteresting. Relevancy scores do not take into account what makes an article interesting, which would vary from user to user. Although methods such as collaborative filtering have been shown to be effective in recommendation sys… more
Date: April 18, 2007
Creator: Pon, R K
Partner: UNT Libraries Government Documents Department
open access

Time reversal invariance - a test in free neutron decay

Description: Time reversal invariance violation plays only a small role in the Standard Model, and the existence of a T-violating effect above the predicted level would be an indication of new physics. A sensitive probe of this symmetry in the weak interaction is the measurement of the T-violating ''D''-correlation in the decay of free neutrons. The triple-correlation D{sigma}{sub n}{center_dot}p{sub e} x p{sub v} involves three kinematic variables, the neutron spin, electron momentu, and neutrino (or proto… more
Date: May 18, 1999
Creator: Lising, Laura J.
Partner: UNT Libraries Government Documents Department
open access

Synthesis and Characterization of Smart Block Copolymers for Biomineralization and Biomedical Applications

Description: Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in … more
Date: August 18, 2008
Creator: Kanapathipillai, Mathumai
Partner: UNT Libraries Government Documents Department
open access

Determination of NAD+ and NADH level in a Single Cell Under H2O2 Stress by Capillary Electrophoresis

Description: A capillary electrophoresis (CE) method is developed to determine both NAD{sup +} and NADH levels in a single cell, based on an enzymatic cycling reaction. The detection limit can reach down to 0.2 amol NAD{sup +} and 1 amol NADH on a home-made CE-LIF setup. The method showed good reproducibility and specificity. After an intact cell was injected into the inlet of a capillary and lysed using a Tesla coil, intracellular NAD{sup +} and NADH were separated, incubated with the cycling buffer, and q… more
Date: August 18, 2008
Creator: Xi, Wenjun
Partner: UNT Libraries Government Documents Department
open access

Pulsed laser deposition of AlMgB14 thin films

Description: Hard, wear-resistant coatings of thin film borides based on AlMgB{sub 14} have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising … more
Date: November 18, 2008
Creator: Russell, Alan; Bastawros, Ashraf & Tan, Xiaoli
Partner: UNT Libraries Government Documents Department
open access

High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

Description: Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods wo… more
Date: August 18, 2006
Creator: Evans, J. W.
Partner: UNT Libraries Government Documents Department
open access

Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

Description: The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immer… more
Date: May 18, 2006
Creator: Jiang, Ximan
Partner: UNT Libraries Government Documents Department
open access

Evolution, Interaction, and Intrinsic Properties of Dislocations in Intermetallics: Anisotropic 3D Dislocation Dynamics Approach

Description: The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline sol… more
Date: August 18, 2008
Creator: Chen, Qian
Partner: UNT Libraries Government Documents Department
open access

CHARGE-EXCHANGE SCATTERING OF NEGATIVE PIONS BY HYDROGEN AT 230,260, 290, 317 AND 371 MeV

Description: The differential cross section for charge-exchange scattering of negative pions by hydrogen has been observed at 230, 260, 290, 317, and 371 Mev. The reaction was observed by detecting one gamma ray from the {pi}{sup 0} decay with a scintillation-counter telescope.
Date: March 18, 1960
Creator: Caris, John C
Partner: UNT Libraries Government Documents Department
open access

Development of Control Models and a Robust Multivariable Controller for Surface Shape Control

Description: Surface shape control techniques are applied to many diverse disciplines, such as adaptive optics, noise control, aircraft flutter control and satellites, with an objective to achieve a desirable shape for an elastic body by the application of distributed control forces. Achieving the desirable shape is influenced by many factors, such as, actuator locations, sensor locations, surface precision and controller performance. Building prototypes to complete design optimizations or controller develo… more
Date: June 18, 2003
Creator: Winters, Scott Eric
Partner: UNT Libraries Government Documents Department
open access

Study of B0 to D(*)0h0 Decay and Measurement ofsin(2beta)

Description: This thesis describes a measurement of a CP violating asymmetry in neutral B meson decays, B{sup 0} yields D{sup *0}h{sup 0}, where D{sup *0} is a charmed meson and h{sup 0} is a light meson, performed on data collected by the BABAR experiment at the SLAC asymmetric-energy electron-positron collider PEP-II.
Date: September 18, 2007
Creator: Bomben, Marco & /SLAC /Trieste U., DMI
Partner: UNT Libraries Government Documents Department
open access

Production and Decay of the K<Sup>0</Sup> Meson

Description: This paper was previously abstracted irom the original language and appears in NSA Vol. 11, as abstract No. 13429. l9565 Selection rules, which occur ln the annihilation of a found nueleon-antinucleon system were examined. The decay of neutral K mesons with allowance for the conservation of combined parity was also investigated. (auth)
Date: May 18, 1959
Creator: Parker, Sherwood
Partner: UNT Libraries Government Documents Department
open access

The Admittance and Transfer Functions of Solid Core Electromagnets

Description: The admittance and transfer functions of large, solidcore electromagnets were determined. The effects of eddy currents and hysteresis were considered in deriving the functions. The study was concerned with the type of magnet employed in nuclear physics research which requires very precise regulation of the magnetic field. The study originated during the design of an analyzing magnet regulator for the ORNL 63-inch cyclotron. (W.D.M.)
Date: January 18, 1960
Creator: Ziegler, N. F.
Partner: UNT Libraries Government Documents Department
open access

Analysis of dynamic testing performed on structural clay tile infilled frames

Description: The behavior of two structural clay tile infilled frames subjected to dynamic loading is investigated. The testing was performed by USACERL using a biaxial shake table machine on which two framed infills were spaced nine feet apart and connected by steel trusses and an eight inch concrete roof slab. The infills were composed of structural clay tile block which were laid with the cores horizontal. The specimen was loaded in both the out-of-plane and in-plane directions using a site specific time… more
Date: December 18, 1994
Creator: Fowler, J. J.
Partner: UNT Libraries Government Documents Department
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