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Magnetic Profiles in Ferromagnetic/Superconducting Superlattices. (open access)

Magnetic Profiles in Ferromagnetic/Superconducting Superlattices.

The interplay between ferromagnetism and superconductivity has been of longstanding fundamental research interest to scientists, as the competition between these generally mutually exclusive types of long-range order gives rise to a rich variety of physical phenomena. A method of studying these exciting effects is by investigating artificially layered systems, i.e. alternating deposition of superconducting and ferromagnetic thin films on a substrate, which enables a straight-forward combination of the two types of long-range order and allows the study of how they compete at the interface over nanometer length scales. While originally studies focused on low temperature superconductors interchanged with metallic ferromagnets, in recent years the scope has broadened to include superlattices of high T{sub c} superconductors and colossal magnetoresistance oxides. Creating films where both the superconducting as well as the ferromagnetic layers are complex oxide materials with similar crystal structures (Figure 1), allows the creation of epitaxial superlattices, with potentially atomically flat and ordered interfaces.
Date: February 28, 2007
Creator: te Velthuis, S. G. E.; Hoffmann, A.; Santamaria, J.; Division, Materials Science & Madrid, Univ. Complutense de
Object Type: Report
System: The UNT Digital Library

Faculty Recital: 2007-10-21 - Opera Potpourri

Access: Use of this item is restricted to the UNT Community
Recital performed at the UNT College of Music Recital Hall.
Date: October 21, 2007
Creator: Sundquist, David
Object Type: Sound
System: The UNT Digital Library
Heavy ion fusion science research for high energy density physics and fusion applications (open access)

Heavy ion fusion science research for high energy density physics and fusion applications

During the past two years, the U.S. heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high brightness beam transport, advanced theory and numerical simulations, and heavy ion target designs for fusion. First experiments combining radial and longitudinal compression of intense ion beams propagating through background plasma resulted in on-axis beam densities increased by 700X at the focal plane. With further improvements planned in 2007, these results will enable initial ion beam target experiments in warm dense matter to begin next year at LBNL. We are assessing how these new techniques apply to low-cost modular fusion drivers and higher-gain direct-drive targets for inertial fusion energy.
Date: June 25, 2007
Creator: Logan, B. G.; Bieniosek, F. M.; Barnard, J. J.; Cohen, R. H.; Coleman, J. E.; Davidson, R. C. et al.
Object Type: Article
System: The UNT Digital Library
Global polarization measurement in Au+Au collisions (open access)

Global polarization measurement in Au+Au collisions

The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.
Date: August 2, 2007
Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of Transverse Single-Spin Asymmetries for Di-JetProduction in Proton-Proton Collisions at sqrt s = 200 GeV (open access)

Measurement of Transverse Single-Spin Asymmetries for Di-JetProduction in Proton-Proton Collisions at sqrt s = 200 GeV

We report the first measurement of the opening angledistribution between pairs of jets produced in high-energy collisions oftransversely polarized protons. The measurement probes (Sivers)correlations between the transverse spin orientation of a proton and thetransverse momentum directions of its partons. With both beams polarized,the wide pseudorapidity (-1 leq eta leq +2) coverage for jets permitsseparation of Sivers functions for the valence and sea regions. Theresulting asymmetries are all consistent with zero and considerablysmaller than Sivers effects observed in semi-inclusive deep inelasticscattering (SIDIS). We discuss theoretical attempts to reconcile the newresults with the sizable transverse spin effects seen in SIDIS andforward hadron production in pp collisions.
Date: October 2, 2007
Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type: Article
System: The UNT Digital Library
Mass, quark-number, and sqrt sNN dependence of the second andfourth flow harmonics in ultra-relativistic nucleus-nucleuscollisions (open access)

Mass, quark-number, and sqrt sNN dependence of the second andfourth flow harmonics in ultra-relativistic nucleus-nucleuscollisions

We present STAR measurements of the azimuthal anisotropyparameter v_2 for pions, kaons, protons, Lambda, bar Lambda, Xi+bar Xi,and \Omega + bar Omega, along with v_4 for pions, kaons, protons, andLambda + bar Lambda at mid-rapidity for Au+Au collisions at sqrt sNN=62.4and 200 GeV. The v_2(p_T) values for all hadron species at 62.4 GeV aresimilar to those observed in 130 and 200 GeV collisions. For observedkinematic ranges, v_2 values at 62.4, 130, and 200 GeV are as little as10 percent-15 percent larger than those in Pb+Pb collisions at sqrt s NN=17.3 GeV. At intermediate transverse momentum (p_T from 1.5-5 GeV/c),the 62.4 GeV v_2(p_T) and v_4(p_T) values are consistent with thequark-number scaling first observed at 200 GeV. A four-particle cumulantanalysis is used to assess the non-flow contributions to pions andprotons and some indications are found for a smaller non-flowcontribution to protons than pions. Baryon v_2 is larger than anti-baryonv_2 at 62.4 and 200 GeV perhaps indicating either that the initialspatial net-baryon distribution is anisotropic, that the mechanismleading to transport of baryon number from beam- to mid-rapidity enhancesv_2, or that anti-baryon and baryon annihilation is larger in thein-plane direction.
Date: January 6, 2007
Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett,J.; Anderson, B. D. et al.
Object Type: Article
System: The UNT Digital Library
The University News (Irving, Tex.), Vol. 38, No. 2, Ed. 1 Tuesday, September 18, 2007 (open access)

The University News (Irving, Tex.), Vol. 38, No. 2, Ed. 1 Tuesday, September 18, 2007

Weekly student newspaper from the University of Dallas in Irving, Texas that includes campus news and commentaries along with advertising.
Date: September 18, 2007
Creator: Crotty, Sarah
Object Type: Newspaper
System: The Portal to Texas History
Design and Analysis of Salmonid Tagging Studies in the Columbia Basin, Volume XXI; A Summary of Methods for Conducting Salmonid Fry Mark-Recapture Studies for Estimating Survival in Tributaries, Technical Report 2005-2006. (open access)

Design and Analysis of Salmonid Tagging Studies in the Columbia Basin, Volume XXI; A Summary of Methods for Conducting Salmonid Fry Mark-Recapture Studies for Estimating Survival in Tributaries, Technical Report 2005-2006.

Productivity and early fry survival can have a major influence on the dynamics of fish stocks. To investigate the early life history of fish, numerous methods have been developed or adapted to these much smaller fish. Some of the marking techniques provide individual identification; many others, only class identification. Some of the tagging techniques require destructive sampling to identify a mark; other methods permit benign examination and rerelease of captured fish. Sixteen alternative release-recapture designs for conducting fry survival investigations were examined. Eleven approaches were found capable of estimating survival parameters; five were not. Of those methods capable of estimating fry survival, five required unique marks, four required batch-specific marks, and two approaches required remarking and rereleasing captured fry. No approach based on a simple batch mark was capable of statistically estimating survival.
Date: February 1, 2007
Creator: Skalski, John
Object Type: Report
System: The UNT Digital Library
[Unverzagt, Das Hotel Balzer!] (open access)

[Unverzagt, Das Hotel Balzer!]

Catalog from the exhibition, "Unverzagt, Das Hotel Balzer!," June 3–July 15, 2007, held at the Künstlerhaus Schloss Balmoral and Kur- und Stadtmuseum. Includes: foreword, essays, list of artworks in the exhibition, selected images, biographical notes. Byrd Williams IV was one of the artists featured in the exhibition.
Date: 2007-06-03/2007-07-15
Creator: unknown
Object Type: Pamphlet
System: The UNT Digital Library
Quantum Perspectives on Physical and Inorganic Chemistry (open access)

Quantum Perspectives on Physical and Inorganic Chemistry

Applications of computational quantum chemistry are presented, including an analysis of the photophysics of cyclic trinuclear coinage metal pyrazolates, an investigation into a potential catalytic cycle utilizing transition metal scorpionates to activate arene C-H bonds, and a presentation of the benchmarking of a new composite model chemistry (the correlation consistent composite approach, ccCA) for the prediction of classical barrier heights. Modeling the pyrazolate photophysics indicates a significant geometric distortion upon excitation and the impact of both metal identity and substituents on the pyrazolates, pointing to ways in which these systems may be used to produce rationally-tuned phosphors. Similarly, thermodynamic and structural investigations into the catalyst system points to promising candidates for clean catalytic activation of arenes. The ccCA was found to reproduce classical reaction barriers with chemical accuracy, outperforming all DFT, ab initio, and composite methods benchmarked.
Date: December 2007
Creator: Grimes-Marchan, Thomas V.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Beyond the "Year of Song": Text and Music in the Song Cycles of Robert Schumann after 1848 (open access)

Beyond the "Year of Song": Text and Music in the Song Cycles of Robert Schumann after 1848

In recent years scholars have begun to re-evaluate the works, writings, and life of Robert Schumann (1810-1856). One of the primary issues in this ongoing re-evaluation is a reassessment of the composer's late works (roughly defined as those written after 1845). Until recently, the last eight years of Schumann's creative life and the works he composed at that time either have been ignored or critiqued under an image of an illness that had caused periodic breakdowns. Schumann's late works show how his culture and the artists communicating within that culture were transformed from the beginning to the middle of the nineteenth century. These late works, therefore, should be viewed in the context of Schumann's output as a whole and in regard to their contributions to nineteenth-century society. Schumann's contributions, specifically to the genre of the song cycle from 1849 to 1852, are among his late compositional works that still await full reconsideration. A topical study, focusing on three themes of selections from his twenty-three late cycles, will provide a critical evaluation of Schumann's compositional output in the genre of the song cycle. First, Schumann's political voice will be examined. The political events that led to the mid-nineteenth-century revolutions inspired crucial …
Date: May 2007
Creator: Ringer, Rebecca Scharlene
Object Type: Thesis or Dissertation
System: The UNT Digital Library
USING ANT COMMUNITIES FOR RAPID ASSESSMENT OF TERRESTRIAL ECOSYSTEM HEALTH (open access)

USING ANT COMMUNITIES FOR RAPID ASSESSMENT OF TERRESTRIAL ECOSYSTEM HEALTH

Ecosystem health with its near infinite number of variables is difficult to measure, and there are many opinions as to which variables are most important, most easily measured, and most robust, Bioassessment avoids the controversy of choosing which physical and chemical parameters to measure because it uses responses of a community of organisms that integrate all aspects of the system in question. A variety of bioassessment methods have been successfully applied to aquatic ecosystems using fish and macroinvertebrate communities. Terrestrial biotic index methods are less developed than those for aquatic systems and we are seeking to address this problem here. This study had as its objective to examine the baseline differences in ant communities at different seral stages from clear cut back to mature pine plantation as a precursor to developing a bioassessment protocol. Comparative sampling was conducted at four seral stages; clearcut, 5 year, 15 year and mature pine plantation stands. Soil and vegetation data were collected at each site. All ants collected were preserved in 70% ethyl alcohol and identified to genus. Analysis of the ant data indicates that ants respond strongly to the habitat changes that accompany ecological succession in managed pine forests and that individual genera …
Date: January 12, 2007
Creator: Wike, L; Doug Martin, D; Michael Paller, M & Eric Nelson, E
Object Type: Article
System: The UNT Digital Library
Computational Studies on Group 14 Elements (C, Si and Ge) in Organometallic and Biological Compounds. (open access)

Computational Studies on Group 14 Elements (C, Si and Ge) in Organometallic and Biological Compounds.

A series of computational studies were carried out on Group 14 (C, Si and Ge) elements in organometallic and biological compounds. Theoretical studies on classical and H-bridged A3H3+ (A=C, Si and Ge) as p ligands with different organometallic fragments at B3LYP and B3P86 level reveal a reverse charge transfer from ligand to metal in Si and Ge complexes whereas in C complexes there is a small charge transfer from metal to ligand. The H-bridged complexes are more stable than the complexes based on Si3H3+ and Ge3H3+ ligands with terminal hydrogens. The stability of the bridged systems increases from Si to Ge. Corrective scale factors for computed harmonic CºO vibrational frequencies for 31 organometallic complexes have been determined at the HF and B3LYP levels. The scaled B3LYP frequencies exhibit a greater reliability than do HF frequencies. Experimental data have shown that Si/Ge-substituted decapeptides are advantageous over their C analog in vitro and in vivo studies in modern hormone therapy. A computational investigation was carried out on the synthesized decapeptides focusing on position 5 containing Si and Ge. The results have shown that there are some differences in C, Si and Ge-containing analogs. However, further investigations are needed to elucidate the observed …
Date: May 2007
Creator: Yu, Liwen
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Improved Biomass Utilization Through Remote Flow Sensing (open access)

Improved Biomass Utilization Through Remote Flow Sensing

The growth of the livestock industry provides a valuable source of affordable, sustainable, and renewable bioenergy, while also requiring the safe disposal of the large quantities of animal wastes (manure) generated at dairy, swine, and poultry farms. If these biomass resources are mishandled and underutilized, major environmental problems will be created, such as surface and ground water contamination, odors, dust, ammonia leaching, and methane emission. Anaerobic digestion of animal wastes, in which microorganisms break down organic materials in the absence of oxygen, is one of the most promising waste treatment technologies. This process produces biogas typically containing {approx}65% methane and {approx}35% carbon dioxide. The production of biogas through anaerobic digestion from animal wastes, landfills, and municipal waste water treatment plants represents a large source of renewable and sustainable bio-fuel. Such bio-fuel can be combusted directly, used in internal combustion engines, converted into methanol, or partially oxidized to produce synthesis gas (a mixture of hydrogen and carbon monoxide) that can be converted to clean liquid fuels and chemicals via Fischer-Tropsch synthesis. Different design and mixing configurations of anaerobic digesters for treating cow manure have been utilized commercially and/or tested on a laboratory scale. These digesters include mechanically mixed, gas recirculation mixed, …
Date: March 26, 2007
Creator: Al-Dahhan, Muthanna; Varma, Rajneesh; Karim, Khursheed; Vesvikar, Mehul; Hoffman, Rebecca; Depaoli, David et al.
Object Type: Report
System: The UNT Digital Library
A Symposium in Honor of William A. Lester, Jr. on His 70thBirthday (open access)

A Symposium in Honor of William A. Lester, Jr. on His 70thBirthday

None
Date: March 19, 2007
Creator: Lester, William A., Jr.
Object Type: Article
System: The UNT Digital Library
The role of EBIT in X-ray laser research (open access)

The role of EBIT in X-ray laser research

Back in the early 1980's the X-ray laser program required a new level of understanding and measurements of the atomic physics of highly charged ions. The electron-beam ion trap (EBIT) was developed and built at Lawrence Livermore National Laboratory (LLNL) as part of the effort to understand and measure the cross sections and wavelengths of highly charged ions. In this paper we will discuss some of the early history of EBIT and how it was used to help in the development of X-ray lasers. EBIT's capability was unique and we will show some of the experimental results obtained over the years that were done related to X-ray lasers. As X-ray lasers have now become a table-top tool we will show some new areas of research that involve understanding the index of refraction in partially ionized plasmas and suggest new areas where EBIT may be able to contribute.
Date: January 25, 2007
Creator: Nilsen, J
Object Type: Article
System: The UNT Digital Library
OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES (open access)

OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES

This chapter provides an overview of some recent research activities on the study of optical and dynamic properties of semiconductor nanomaterials. The emphasis is on unique aspects of these properties in nanostructures as compared to bulk materials. Linear, including absorption and luminescence, and nonlinear optical as well as dynamic properties of semiconductor nanoparticles are discussed with focus on their dependence on particle size, shape, and surface characteristics. Both doped and undoped semiconductor nanomaterials are highlighted and contrasted to illustrate the use of doping to effectively alter and probe nanomaterial properties. Some emerging applications of optical nanomaterials are discussed towards the end of the chapter, including solar energy conversion, optical sensing of chemicals and biochemicals, solid state lighting, photocatalysis, and photoelectrochemistry.
Date: September 28, 2007
Creator: Grant, C D & Zhang, J Z
Object Type: Article
System: The UNT Digital Library
Phases of N=\infty Gauge Theories on S^3 \times S^1 and Nonperturbative Orbifold-orientifold Equivalences (open access)

Phases of N=\infty Gauge Theories on S^3 \times S^1 and Nonperturbative Orbifold-orientifold Equivalences

We study the phase diagrams of N = {infinity} vector-like, asymptotically free gauge theories as a function of volume, on S{sup 3} x S{sup 1}. The theories of interest are the ones with fermions in two index representations [adjoint, (anti)symmetric, and bifundamental abbreviated as QCD(adj), QCD(AS/S) and QCD(BF)], and are interrelated via orbifold or orientifold projections. The phase diagrams reveal interesting phenomena such as disentangled realizations of chiral and center symmetry, confinement without chiral symmetry breaking, zero temperature chiral transitions, and in some cases, exotic phases which spontaneously break the discrete symmetries such as C, P, T as well as CPT. In a regime where the theories are perturbative, the deconfinement temperature in SYM, and QCD(AS/S/BF) coincide. The thermal phase diagrams of thermal orbifold QCD(BF), orientifold QCD(AS/S), and N = 1 SYM coincide, provided charge conjugation symmetry for QCD(AS/S) and Z{sub 2} interchange symmetry of the QCD(BF) are not broken in the phase continuously connected to R{sup 4} limit. When the S{sup 1} circle is endowed with periodic boundary conditions, the (nonthermal) phase diagrams of orbifold and orientifold QCD are still the same, however, both theories possess chirally symmetric phases which are absent in N=1 SYM. The match and mismatch …
Date: March 6, 2007
Creator: Unsal, Mithat
Object Type: Article
System: The UNT Digital Library
Photophysical studies of silver(I), platinum(II), palladium(II), and nickel(II) complexes and their use in electronic devices. (open access)

Photophysical studies of silver(I), platinum(II), palladium(II), and nickel(II) complexes and their use in electronic devices.

This dissertation deals with two major topics that involve spectroscopic studies of (a) divalent group 10 metals and (b) silver(I)-phosphine complexes. The scope of the work involved the delineation of the electronic structure of these complexes in different environments and their use in electronic devices. The first topic is a look at the luminescence of tetrahedral silver(I)-phosphine complexes. Broad unstructured emissions with large Stokes shifts were found for these complexes. Computational analysis of the singlet and triplet state geometries suggests that this emission is due to a Jahn-Teller type distortion. The second topic represents the major thrust of this research, which is an investigation into the electronic structure of M(diimine)X2 (M= Pt(II), Pd(II), or Ni(II); X = dichloro, or dithiolate ligands) complexes and their interactions with an electron acceptor or Lewis acid. Chapter 3 assesses the use of some of these complexes in dye sensitized solar cells (DSSCs); it is shown that these complexes may lead to a viable alternative to the more expensive ruthenium-based dyes that are being implemented now. Chapter 4 is an investigation into donor/acceptor pairs involving this class of complexes, which serves as a feasibility test for the use of these complexes in organic photo-voltaics (OPVs) …
Date: December 2007
Creator: Hudson, Joshua M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Dem Schwerte Muss Der Pflug Folgen: Űber-Peasants and National Socialist Settlements in the Occupied Eastern Territories during World War Two (open access)

Dem Schwerte Muss Der Pflug Folgen: Űber-Peasants and National Socialist Settlements in the Occupied Eastern Territories during World War Two

German industrialization in the nineteenth century had brought forward a variety of conflicting ideas when it came to the agrarian community. One of them was the agrarian romantic movement led by Adam Műller, who feared the loss of the traditional German peasant. Műller influenced Reichdeutsche Richard Walther Darré, who argued that large cities were the downfall of the German people and that only a healthy peasant stock would be able to ‘save' Germany. Under Darré's definition, “Geopolitik” was the defense of the land, the defense with Pflug und Schwert (plow and sword) by Wehrbauern, an ‘Űberbauer-fusion' of soldier and peasant. In order to accomplish these goals, new settlements had to be established while moving from west to east. The specific focus of this study is on the original Hegewald resettlement ideas of Richard Walther Darré and how his philosophy was taken over by Himmler and fit into his personal needs and creed after 1941. It will shed some light on the interaction of Darré and Himmler and the notorious internal fights and power struggles between the various governmental agencies involved. The Ministry for Food and Agriculture under the leadership of Darré was systematically pushed into the background and all previous, …
Date: May 2007
Creator: De Santiago Ramos, Simone C.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Oklahoma Daily (Norman, Okla.), Vol. 92, No. 72, Ed. 1 Thursday, November 29, 2007 (open access)

The Oklahoma Daily (Norman, Okla.), Vol. 92, No. 72, Ed. 1 Thursday, November 29, 2007

Student newspaper of the University of Oklahoma in Norman, Oklahoma that includes national, local, and campus news along with advertising.
Date: November 29, 2007
Creator: Zaman, Ashiq
Object Type: Newspaper
System: The Gateway to Oklahoma History
DNA Repair Decline During Mouse Spermiogenesis Results in the Accumulation of Heritable DNA Damage (open access)

DNA Repair Decline During Mouse Spermiogenesis Results in the Accumulation of Heritable DNA Damage

The post-meiotic phase of mouse spermatogenesis (spermiogenesis) is very sensitive to the genomic effects of environmental mutagens because as male germ cells form mature sperm they progressively lose the ability to repair DNA damage. We hypothesized that repeated exposures to mutagens during this repair-deficient phase result in the accumulation of heritable genomic damage in mouse sperm that leads to chromosomal aberrations in zygotes after fertilization. We used a combination of single or fractionated exposures to diepoxybutane (DEB), a component of tobacco smoke, to investigate how differential DNA repair efficiencies during the three weeks of spermiogenesis affected the accumulation of DEB-induced heritable damage in early spermatids (21-15 days before fertilization, dbf), late spermatids (14-8 dbf) and sperm (7-1 dbf). Analysis of chromosomal aberrations in zygotic metaphases using PAINT/DAPI showed that late spermatids and sperm are unable to repair DEB-induced DNA damage as demonstrated by significant increases (P&lt;0.001) in the frequencies of zygotes with chromosomal aberrations. Comparisons between single and fractionated exposures suggested that the DNA repair-deficient window during late spermiogenesis may be less than two weeks in the mouse and that during this repair-deficient window there is accumulation of DNA damage in sperm. Finally, the dose-response study in sperm indicated a …
Date: December 1, 2007
Creator: Marchetti, Francesco; Marchetti, Francesco & Wyrobek, Andrew J.
Object Type: Report
System: The UNT Digital Library
Demonstration of An Integrated Approach to Mercury Control at Lee Station (open access)

Demonstration of An Integrated Approach to Mercury Control at Lee Station

General Electric (GE) has developed an approach whereby native mercury reduction on fly ash can be improved by optimizing the combustion system. This approach eliminates carbon-rich areas in the combustion zone, making the combustion process more uniform, and allows increasing carbon content in fly ash without significant increase in CO emissions. Since boiler excess O{sub 2} can be also reduced as a result of optimized combustion, this process reduces NO{sub x} emissions. Because combustion optimization improves native mercury reduction on fly ash, it can reduce requirements for activated carbon injection (ACI) when integrated with sorbent injection for more efficient mercury control. The approach can be tailored to specific unit configurations and coal types for optimal performance. This report describes results of a U.S. DOE sponsored project designed to evaluate the effect of combustion conditions on 'native' mercury capture on fly ash and integrate combustion optimization for improved mercury and NO{sub x} reduction with ACI. The technology evaluation took place in Lee Station Unit 3 located in Goldsboro, NC and operated by Progress Energy. Unit 3 burns a low-sulfur Eastern bituminous coal and is a 250 MW opposed-wall fired unit equipped with an ESP with a specific collection area of 249 …
Date: December 31, 2007
Creator: Lissianski, Vitali & Maly, Pete
Object Type: Report
System: The UNT Digital Library
Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate (open access)

Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate

New high-performance ferroelectric materials based on Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) that are doped with cryolite-type strontium niobate (SNO, Sr{sub 4}(Sr{sub 2-2y/3}Nb{sub 2+2y/3})O{sub 11+y}V{sub 0,1-y} with 0 {le} y {le} 1), hence denoted PZT:SNO, and their microscopic structure are described. The combination of exceptional piezoelectric properties, i.e. a piezoelectric strain constant of d{sub 33} {approx} 760 pm/V, with excellent stability and degradation resistance makes ferroelectric PZT:SNO solid solutions very attractive for use in novel and innovative piezoelectric actuator and transducer applications. Extended X-ray absorption fine-structure (EXAFS) analyses of PZT:SNO samples revealed that {approx}10 % of the Sr cations occupy the nominal B-sites of the perovskite-type PZT host lattice. This result was supported by EXAFS analyses of both a canonical SrTiO{sub 3} perovskite and two SNO model and reference compounds. Fit models that do not account for Sr cations on B-sites were ruled out. A clear Sr-Pb peak in Fourier transformed EXAFS data visually confirmed this structural model. The generation of temporary oxygen vacancies and the intricate defect chemistry induced by SNO-doping of PZT are crucial for the exceptional materials properties exhibited by PZT:SNO materials.
Date: April 26, 2007
Creator: Feltz, A.; Schmidt-Winkel, P.; Schossman, M.; Booth, C.H. & Albering, J.
Object Type: Article
System: The UNT Digital Library