90 Matching Results

Search Results

Results: 1 - 24 next
open access

Paralization and check pointing of GPU applications through program transformation

Description: GPUs have emerged as a powerful tool for accelerating general-purpose applications. The availability of programming languages that makes writing general-purpose applications for running on GPUs tractable have consolidated GPUs as an alternative for accelerating generalpurpose applications. Among the areas that have bene#12;ted from GPU acceleration are: signal and image processing, computational uid dynamics, quantum chemistry, and, in general, the High Performance Computing (HPC) Industry. In … more
Date: November 15, 2012
Creator: Solano-Quinde, Lizandro Dami#19 & Laboratory], an
Partner: UNT Libraries Government Documents Department
open access

Measurement of the D_s Decay Constant f_Ds and Observation of New Charm Resonances Decaying to D^(*)\pi

Description: The absolute branching fractions for the decays D{sub s}{sup -} {yields} {ell}{sup -}{bar {nu}}{sub {ell}} ({ell} = e, {mu}, or {tau}) are measured using a data sample corresponding to an integrated luminosity of 521 fb{sup -1} collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEPII e{sup +}e{sup -} collider at SLAC. The number of D{sub s}{sup -} mesons is determined by reconstructing the recoiling system DKX{gamma} in events of the type e{sup +}e{sup -} {yields… more
Date: March 15, 2012
Creator: Benitez, Jose
Partner: UNT Libraries Government Documents Department
open access

Study of CP Violation in Dalitz-Plot Analyses of B-Meson Decays to Three Kaons

Description: The Standard Model (SM) explains CP violation in terms of the CKM matrix. The BABAR experiment was designed mainly to test the CKM model in B decays. B decays that proceed through b {yields} s loop diagrams, of which B {yields} KKK decays are an example, are sensitive to new physics effects that could lead to deviations from the CKM predictions for CP violation. We present studies of CP violation in the decays B{sup +} {yields} K{sup +}K{sup -}K{sup +}, B{sup +} {yields} K{sub S}{sup 0}K{sub S}… more
Date: February 15, 2012
Creator: Lindquist, Brian
Partner: UNT Libraries Government Documents Department
open access

Campbell penetration depth in Fe-based superconductors

Description: A 'true' critical current density, j{sub c}, as opposite to commonly measured relaxed persistent (Bean) current, j{sub B}, was extracted from the Campbell penetration depth, {lambda}{sub c}(T,H) measured in single crystals of LiFeAs, and optimally electron-doped Ba(Fe{sub 0.954}Ni{sub 0.046}){sub 2}As{sub 2} (FeNi122). In LiFeAs, the effective pinning potential is nonparabolic, which follows from the magnetic field - dependent Labusch parameter {alpha}. At the equilibrium (upon field - cooling)… more
Date: August 15, 2011
Creator: Prommapan, Plegchart
Partner: UNT Libraries Government Documents Department
open access

Improving the phase stability and oxidation resistance of B-NiAl

Description: High temperature alloys are essential to many industries that require a stable material to perform in harsh oxidative environments. Many of these alloys are suited for specific applications such as jet engine turbine blades where most other materials would either melt or oxidize and crumble (1). These alloys must have a high melting temperature, excellent oxidation resistance, good creep resistance, and decent fracture toughness to be successfully used in such environments. The discovery of Ni … more
Date: August 15, 2011
Creator: Brammer, Travis
Partner: UNT Libraries Government Documents Department
open access

Indirectly detected chemical shift correlation NMR spectroscopy in solids under fast magic angle spinning

Description: The development of fast magic angle spinning (MAS) opened up an opportunity for the indirect detection of insensitive low-{gamma} nuclei (e.g., {sup 13}C and {sup 15}N) via the sensitive high-{gamma} nuclei (e.g., {sup 1}H and {sup 19}F) in solid-state NMR, with advanced sensitivity and resolution. In this thesis, new methodology utilizing fast MAS is presented, including through-bond indirectly detected heteronuclear correlation (HETCOR) spectroscopy, which is assisted by multiple RF pulse seq… more
Date: August 15, 2011
Creator: Mao, Kanmi
Partner: UNT Libraries Government Documents Department
open access

Phase-field investigation on the non-equilibrium interface dynamics of rapid alloy solidification

Description: The research program reported here is focused on critical issues that represent conspicuous gaps in current understanding of rapid solidification, limiting our ability to predict and control microstructural evolution (i.e. morphological dynamics and microsegregation) at high undercooling, where conditions depart significantly from local equilibrium. More specifically, through careful application of phase-field modeling, using appropriate thin-interface and anti-trapping corrections and addressi… more
Date: August 15, 2011
Creator: Choi, Jeong
Partner: UNT Libraries Government Documents Department
open access

Theory of spin-fluctuation induced superconductivity in iron-based superconductors

Description: In this dissertation we focus on the investigation of the pairing mechanism in the recently discovered high-temperature superconductor, iron pnictides. Due to the proximity to magnetic instability of the system, we considered short-range spin fluctuations as the major mediating source to induce superconductivity. Our calculation supports the magnetic fluctuations as a strong candidate that drives Cooper-pair formation in this material. We find the corresponding order parameter to be of the so-c… more
Date: August 15, 2011
Creator: Zhang, Junhua
Partner: UNT Libraries Government Documents Department
open access

Mesoporous silica nanoparticles as smart and safe devices for regulating blood biomolecule levels

Description: Stimuli-responsive end-capped MSN materials are promising drug carriers that securely deliver a large payload of drug molecules without degradation or premature release. A general review of the recent progress in this field is presented, including a summary of a series of hard and soft caps for drug encapsulation and a variety of internal and external stimuli for controlled release of different therapeutics, a discussion of the biocompatibility of MSN both in vitro and in vivo, and a descriptio… more
Date: May 15, 2011
Creator: Zhao, Yan
Partner: UNT Libraries Government Documents Department
open access

Mesoporous silica nanoparticles for biomedical and catalytical applications

Description: Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mes… more
Date: May 15, 2011
Creator: Sun, Xiaoxing
Partner: UNT Libraries Government Documents Department
open access

Self-assembled pentablock copolymers for selective and sustained gene delivery

Description: The poly(diethylaminoethyl methacrylate) (PDEAEM) - Pluronic F127 - PDEAEM pentablock copolymer (PB) gene delivery vector system has been found to possess an inherent selectivity in transfecting cancer cells over non-cancer cells in vitro, without attaching any targeting ligands. In order to understand the mechanism of this selective transfection, three possible intracellular barriers to transfection were investigated in both cancer and non-cancer cells. We concluded that escape from the endocy… more
Date: May 15, 2011
Creator: Zhang, Bingqi
Partner: UNT Libraries Government Documents Department
open access

Studies of the structure and function of Mms6, a bacterial protein that promotes the formation of magnetic nanoparticles

Description: Here we report structural and functional studies of Mms6, a biomineralization protein that can promote the formation in vitro of magnetic nanoparticles with sizes and morphologies similar to the magnetites synthesized by magnetotactic bacteria. We found the binding pattern of Mms6 to ferric ion to be two-phase and multivalent. We quantatively determined that Mms6 binds one Fe{sup 3+} with a very high affinity (K{sub d} = 10{sup -16} M). The second phase of iron binding is multivalent and cooper… more
Date: May 15, 2011
Creator: Wang, Lijun
Partner: UNT Libraries Government Documents Department
open access

The theoretical study of passive and active optical devices via planewave based transfer (scattering) matrix method and other approaches

Description: In this thesis, we theoretically study the electromagnetic wave propagation in several passive and active optical components and devices including 2-D photonic crystals, straight and curved waveguides, organic light emitting diodes (OLEDs), and etc. Several optical designs are also presented like organic photovoltaic (OPV) cells and solar concentrators. The first part of the thesis focuses on theoretical investigation. First, the plane-wave-based transfer (scattering) matrix method (TMM) is bri… more
Date: May 15, 2011
Creator: Zhuo, Ye
Partner: UNT Libraries Government Documents Department
open access

Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

Description: This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} (Tl2201) T{sub c,max} {approx} 95 K and (Bi{sub 1.35}Pb{sub 0.85})(Sr{sub 1.47}La{sub 0.38})CuO{sub 6+{delta}} (Bi2201) T{sub c,max} {approx} 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's … more
Date: December 15, 2010
Creator: Palczewski, Ari Deibert
Partner: UNT Libraries Government Documents Department
open access

Developing new optical imaging techniques for single particle and molecule tracking in live cells

Description: Differential interference contrast (DIC) microscopy is a far-field as well as wide-field optical imaging technique. Since it is non-invasive and requires no sample staining, DIC microscopy is suitable for tracking the motion of target molecules in live cells without interfering their functions. In addition, high numerical aperture objectives and condensers can be used in DIC microscopy. The depth of focus of DIC is shallow, which gives DIC much better optical sectioning ability than those of ph… more
Date: December 15, 2010
Creator: Sun, Wei
Partner: UNT Libraries Government Documents Department
open access

Devitrification kinetics and phase selection mechanisms in Cu-Zr metallic glasses

Description: Metallic glasses have been a promising class of materials since their discovery in the 1960s. Indeed, remarkable chemical, mechanical and physical properties have attracted considerable attention, and several excellent reviews are available. Moreover, the special group of glass forming alloys known as the bulk metallic glasses (BMG) become amorphous solids even at relatively low cooling rates, allowing them to be cast in large cross sections, opening the scope of potential applications to inclu… more
Date: December 15, 2010
Creator: Kalay, Ilkay
Partner: UNT Libraries Government Documents Department
open access

Dislocation dynamics simulations of plasticity at small scales

Description: As metallic structures and devices are being created on a dimension comparable to the length scales of the underlying dislocation microstructures, the mechanical properties of them change drastically. Since such small structures are increasingly common in modern technologies, there is an emergent need to understand the critical roles of elasticity, plasticity, and fracture in small structures. Dislocation dynamics (DD) simulations, in which the dislocations are the simulated entities, offer a w… more
Date: December 15, 2010
Creator: Zhou, Caizhi
Partner: UNT Libraries Government Documents Department
open access

Extending the frontiers of mass spectrometric instrumentation and methods

Description: The focus of this dissertation is two-fold: developing novel analysis methods using mass spectrometry and the implementation and characterization of a novel ion mobility mass spectrometry instrumentation. The novel mass spectrometry combines ion trap for ion/ion reactions coupled to an ion mobility cell. The long term goal of this instrumentation is to use ion/ion reactions to probe the structure of gas phase biomolecule ions. The three ion source - ion trap - ion mobility - qTOF mass spectrome… more
Date: December 15, 2010
Creator: Schieffer, Gregg
Partner: UNT Libraries Government Documents Department
open access

Input/Output of ab-initio nuclear structure calculations for improved performance and portability

Description: Many modern scientific applications rely on highly computation intensive calculations. However, most applications do not concentrate as much on the role that input/output operations can play for improved performance and portability. Parallelizing input/output operations of large files can significantly improve the performance of parallel applications where sequential I/O is a bottleneck. A proper choice of I/O library also offers a scope for making input/output operations portable across differ… more
Date: December 15, 2010
Creator: Laghave, Nikhil
Partner: UNT Libraries Government Documents Department
open access

Magnetic nanoparticles for applications in oscillating magnetic field

Description: Enzymatic and thermochemical catalysis are both important industrial processes. However, the thermal requirements for each process often render them mutually exclusive: thermochemical catalysis requires high temperature that denatures enzymes. One of the long-term goals of this project is to design a thermocatalytic system that could be used with enzymatic systems in situ to catalyze reaction sequences in one pot; this system would be useful for numerous applications e.g. conversion of biomass … more
Date: December 15, 2010
Creator: Peeraphatdit, Chorthip
Partner: UNT Libraries Government Documents Department
open access

Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

Description: The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) … more
Date: December 15, 2010
Creator: Jing, Dapeng
Partner: UNT Libraries Government Documents Department
open access

Microstructures and oxidation behavior of some Molybdenum based alloys

Description: The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low… more
Date: December 15, 2010
Creator: Ray, Pratik Kumar
Partner: UNT Libraries Government Documents Department
open access

Reducing the losses of optical metamaterials

Description: The field of metamaterials is driven by fascinating and far-reaching theoretical visions, such as perfect lenses, invisibility cloaking, and enhanced optical nonlinearities. However, losses have become the major obstacle towards real world applications in the optical regime. Reducing the losses of optical metamaterials becomes necessary and extremely important. In this thesis, two approaches are taken to reduce the losses. One is to construct an indefinite medium. Indefinite media are materials… more
Date: December 15, 2010
Creator: Fang, Anan
Partner: UNT Libraries Government Documents Department
Back to Top of Screen