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Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

Description: Among the olivine-structured metal phosphate family, LiMnPO{sub 4} exhibits a high discharge potential (4V), which is still compatible with common electrolytes, making it interesting for use in the next generation of Li ion batteries. The extremely low electronic conductivity of this material severely limits its electrochemical performance, however. One strategy to overcome this limitation is to make LiMnPO{sub 4} nanoparticulate to decrease the diffusion distance. Another is to add a carbon or… more
Date: May 15, 2008
Creator: Chen, Jiajun; Doeff, Marca M. & Wang, Ruigang
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Spatial resolution limits for synchrotron-based infrared spectromicroscopy

Description: Detailed spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source synchrotron facility in Berkeley, CA. The high-brightness synchrotron source is coupled at this beamline to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests in both the mid-IR (using a KBr beamsplitter and an MCT-A* detector) and in the near-IR (using a CaF2 beamsplitter and an InGaAS detector) were performed and compared to a simple diffraction-limited spot size mod… more
Date: October 15, 2007
Creator: Levenson, Erika; Lerch, Philippe & Martin, Michael C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Organic carbon distribution, speciation, and elementalcorrelations within soil microaggregates: applications of STXM and NEXAFSspectroscopy

Description: Soils contain the largest inventory of organic carbon on the Earth's surface. Therefore, it is important to understand how soil organic carbon (SOC) is distributed in soils. This study directly measured SOC distributions within soil microaggregates and its associations with major soil elements from three soil groups (Phaeozem, Cambisol, and Ultisol), using scanning transmission X-ray microscopy (STXM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at a spatial resolution of… more
Date: March 15, 2007
Creator: Wan, Jiamin; Tyliszczak, Tolek & Tokunaga, Tetsu K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

Description: Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identifi… more
Date: February 15, 2008
Creator: Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O'Brien, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Antisense oligodeoxynucleotide inhibition as a potent diagnostic tool for gene function in plant biology

Description: Antisense oligodeoxynucleotide (ODN) inhibition emerges as an effective means for probing gene function in plant cells. Employing this method we have established the importance of the SUSIBA2 transcription factor for regulation of starch synthesis in barley endosperm, and arrived at a model for the role of the SUSIBAs in sugar signaling and source-sink commutation during cereal endosperm development. In this addendum we provide additional data demonstrating the suitability of the antisense ODN … more
Date: January 15, 2008
Creator: Jansson, Christer; Sun, Chuanxin; Ghebramedhin, Haile; Hoglund, Anna-Stina & Jansson, Christer
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition

Description: Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 n… more
Date: September 15, 2008
Creator: Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

Description: Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence … more
Date: August 15, 2008
Creator: Coble, Inger M
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Atomic structure of nanometer-sized amorphous TiO2

Description: Amorphous titania (TiO{sub 2}) is an important precursor for synthesis of single-phase nanocrystalline anatase. We synthesized x-ray amorphous titania by hydrolysis of titanium ethoxide at the ice point. Transmission electron microscopy examination and nitrogen gas adsorption indicated the particle size of the synthesized titania is {approx} 2 nm. Synchrotron wide-angle x-ray scattering (WAXS) was used to probe the atomic correlations in this amorphous sample. Atomic pair-distribution function … more
Date: October 15, 2008
Creator: Zhang, H.; Chen, B.; Banfield, J. F. & Waychunas, G. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Tunable Tensor Voting Improves Grouping of Membrane-Bound Macromolecules

Description: Membrane-bound macromolecules are responsible for structural support and mediation of cell-cell adhesion in tissues. Quantitative analysis of these macromolecules provides morphological indices for damage or loss of tissue, for example as a result of exogenous stimuli. From an optical point of view, a membrane signal may have nonuniform intensity around the cell boundary, be punctate or diffused, and may even be perceptual at certain locations along the boundary. In this paper, a method for the… more
Date: April 15, 2009
Creator: Loss, Leandro A.; Bebis, George & Parvin, Bahram
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Applications of a single-molecule detection in early disease diagnosis and enzymatic reaction study

Description: Various single-molecule techniques were utilized for ultra-sensitive early diagnosis of viral DNA and antigen and basic mechanism study of enzymatic reactions. DNA of human papilloma virus (HPV) served as the screening target in a flow system. Alexa Fluor 532 (AF532) labeled single-stranded DNA probes were hybridized to the target HPV-16 DNA in solution. The individual hybridized molecules were imaged with an intensified charge-coupled device (ICCD) in two ways. In the single-color mode, target… more
Date: October 15, 2008
Creator: Li, Jiangwei
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Detecting estrogenic activity in water samples withestrogen-sensitive yeast cells using spectrophotometry and fluorescencemicroscopy

Description: Environmental estrogens are environmental contaminants that can mimic the biological activities of the female hormone estrogen in the endocrine system, i.e. they act as endocrine disrupters. Several substances are reported to have estrogen-like activity or estrogenic activity. These include steroid hormones, synthetic estrogens (xenoestrogens), environmental pollutants and phytoestrogens (plant estrogens). Using the chromogenic substrate ortho-nitrophenyl-{beta}-D-galactopyranoside (ONPG) we sh… more
Date: March 15, 2006
Creator: Wozei, E.; Holman, H-Y.N.; Hermanowicz, S.W. & S., Borglin
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

DISSOLUTION OF FB-LINE METAL RESIDUES CONTAINING BERYLLIUM IN H-CANYON

Description: Scrap materials containing plutonium (Pu) metal from FB-Line vaults are currently being dissolved in HB-Line for subsequent disposition through the H-Canyon facility. However, milestone and schedule commitments may require the dissolution of material containing Pu and beryllium (Be) metals in H-Canyon. To support this option, a flowsheet for dissolving Pu and Be metals in H-Canyon was demonstrated using a 4 M nitric acid (HNO{sub 3}) solution containing 0.3 M fluoride (F{sup -}). The F{sup -} w… more
Date: July 15, 2005
Creator: Rudisill, Tracy S.; Crowder, Mark L. & Bronikowski, Michael G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

Description: Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current disser… more
Date: October 15, 2008
Creator: Kalay, Yunus Eren
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Specimen charging on thin films with one conducting layer:Discussion of physical principles

Description: While the most familiar consequences of specimen charging in transmission electron microscopy can be eliminated by evaporating a thin conducting film (such as a carbon film) onto an insulating specimen, or by preparing samples directly on such a conducting film to begin with, a more subtle charging effect still remains. We argue here that specimen charging is in this case likely to produce a dipole sheet rather than a layer of positive charge at the surface of the specimen. A simple model of th… more
Date: April 15, 2003
Creator: Glaeser, Robert M. & Downing, Kenneth H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Dispersion of Metals from Abandoned Mines and their Effect on Biota in the Methow River, Okanogan County, Washington: Final Report 2002-2003.

Description: A study of mine-waste contamination effects on Methow River habitat on the eastern slopes of the north Cascade Mountains in Washington state, U.S.A., revealed impacts at ecosystem, community, population, individual, tissue, and cellular levels. Ore deposits in the area were mined for gold, silver, copper and zinc until the early 1950's, but the mines are now inactive. An above-and-below-mine approach was used to compare potentially impacted to control sites. The concentrations of eleven trace e… more
Date: May 15, 2003
Creator: Peplow, Dan & Edmonds, Robert
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Comparison of AlxGa1-xN films grown on sapphire by MBE underN-rich and Ga-rich conditions

Description: Al{sub x}Ga{sub 1-x}N layers grown under N-rich and Ga-rich conditions were investigated using transmission electron microscopy (TEM) and photoluminescence (PL). Despite a high density of threading dislocations ({approx}10{sup 10} cm{sup -2}) these layers had high PL quantum efficiencies. Both, TEM and PL studies showed significant differences between layers grown under N- and Ga-rich conditions. The results indicate that edge dislocations do contribute to nonradiative recombination in Al{sub x… more
Date: October 15, 2002
Creator: Jasinski, J.; Liliental-Weber, Z.; He, L.; Reshchikov, M.A. & Morkoc, H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Pyramidal Defects in GaN:Mg Grown with Ga Polarity

Description: Transmission electron microscopy (TEM) studies show formation of different types of Mg-rich defects in GaN. Types of defects strongly depend on crystal growth polarity. For bulk crystals grown with N-polarity, the planar defects are distributed at equal distances (20 unit cells of GaN). For growth with Ga-polarity (for both bulk and MOCVD grown crystals) a different type of defects have been found. These defects are three-dimensional Mg-rich hexagonal pyramids (or trapezoids) with their base on… more
Date: February 15, 2005
Creator: Liliental-Weber, Zuzanna; Tomaszewicz, Tomasz; Zakharov, Dmitri & O'Keefe, Michael A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The epsilon Phase in the UO2 of the Oklo Natural Reactors

Description: In spent nuclear fuel (SNF), the metal epsilon phase consists of an alloy of Mo-Ru-Pd-Tc-Rh, occurring at a micron to sub-micron scale. {sup 99}Tc has a long half life (2.13 x 10{sup 5} years) and can be an important contributor to dose in safety assessments of nuclear waste repositories. Under oxidizing conditions, TcO{sub 4}{sup -} is the predominant species of Tc. In this form, Tc is highly soluble and weakly adsorbed onto mineral surfaces. Because the Oklo reactors are 2.0 billion years old… more
Date: April 15, 2005
Creator: Utsunomiya, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effect of GaN template layer strain on the growth of InxGa1-xN/GaN MQW light emitting diodes

Description: GaN template layer strain effects were investigated on the growth of InGaN/GaN LED devices. Seven period InGaN/GaN multiple quantum well structures were deposited on 5{micro}m and 15{micro}m GaN template layers. It was found that the electroluminescence emission of the 15{micro}m device was red-shifted by approximately 132meV. Triple-axis X-Ray Diffraction and Cross-Sectional Transmission Electron Microscopy show that the 15{micro}m templay layer device was virtually unstrained while the 5{micr… more
Date: January 15, 2004
Creator: Johnson, M. C.; Bourret-Courchesne, E. D.; Wu, J.; Liliental-Weber, Z.; Zakharov, D. N.; Jorgenson, R. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Science of Electrode Materials for Lithium Batteries - Progress Report

Description: OAK-B135 (IPLD Cleared) Basic materials science research on materials for anodes and cathodes in electrochemical cells. The work is a mix of electrochemical measurements and analysis of the materials by transmission electron microscopy and x-ray diffractometry. The emphasis is on the thermodynamics and kinetics of how lithium is intercalated and de-intercalleted into anode and cathod materials.
Date: August 15, 2003
Creator: Fultz, Brent
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Influence of Thermal Aging on the Mechanical and Corrosion Properties of C-22 Alloy Welds

Description: The phase stability of C-22 alloy (UNS No. N06022) gas tungsten arc welds was studied by aging samples at 427, 482, 538, 593, 649, 704, and 760 C for times up to 40,000 hours. The tensile properties and the Charpy impact toughness of these samples were measured in the as-welded condition as well as after aging. The corrosion resistance was measured using standard immersion tests in acidic ferric sulfate (ASTM G 28 A) and 2.5% hydrochloric acid solutions at the boiling point. The microstructures… more
Date: June 15, 2000
Creator: Edgecumbe Summers, T. S.; Rebak, R. B. & Seeley, R. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Screw dislocations in GaN

Description: GaN has received much attention over the past few years because of several new applications, including light emitting diodes, blue laser diodes and high-power microwave transistors. One of the biggest problems is a high density of structural defects, mostly dislocations, due to a lack of a suitable lattice-matched substrate since bulk GaN is difficult to grow in large sizes. Transmission Electron Microscopy (TEM) has been applied to study defects in plan-view and cross-sections on samples prepa… more
Date: February 15, 2002
Creator: Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack & O'Keefe, Michael A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Transmission electron microscopy analysis of corroded metal waste forms.

Description: This report documents the results of analyses with transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (ED) of samples of metallic waste form (MWF) materials that had been subjected to various corrosion tests. The objective of the TEM analyses was to characterize the composition and microstructure of surface alteration products which, when combined with other test results, can be used to determine the matrix corr… more
Date: April 15, 2005
Creator: Dietz, N. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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