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Chemical Bonding and Structural Information of Black Carbon Reference Materials and Individual Carbonaceous Atmospheric Aerosols

Description: The carbon-to-oxygen ratios and graphitic nature of a rangeof black carbon standard reference materials (BC SRMs), high molecularmass humic-like substances (HULIS) and atmospheric particles are examinedusing scanning transmission X-ray microscopy (STXM) coupled with nearedge X-ray absorption fine structure (NEXAFS) spectroscopy. UsingSTXM/NEXAFS, individual particles with diameter>100 nm are studied,thus the diversity of atmospheric particles collected during a variety offield missions is asses… more
Date: April 25, 2007
Creator: Hopkins, Rebecca J.; Tivanski, Alexei V.; Marten, Bryan D. & Gilles, Mary K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Interactions of Oxygen and Hydrogen on Pd(111) surface

Description: The coadsorption and interactions of oxygen and hydrogen on Pd(1 1 1) was studied by scanning tunneling microscopy and density functional theory calculations. In the absence of hydrogen oxygen forms a (2 x 2) ordered structure. Coadsorption of hydrogen leads to a structural transformation from (2 x 2) to a ({radical}3 x {radical}3)R30 degree structure. In addition to this transformation, hydrogen enhances the mobility of oxygen. To explain these observations, the interaction of oxygen and hydro… more
Date: June 25, 2008
Creator: Demchenko, D.O.; Sacha, G.M.; Salmeron, M. & Wang, L.-W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Examination of the local structure in composite and low dimensional semiconductor by X-ray Absorption Spectroscopy

Description: X-ray absorption methods have been successfully used to obtain quantitative information about local atomic composition of two different materials. X-ray Absorption Near Edge Structure analysis and X-Ray Photoelectron Spectroscopy allowed us to determine seven chemical compounds and their concentrations in c-BN composite. Use of Extended X-ray Absorption Fine Structure in combination with Transmission Electron Microscopy enabled us to determine the composition and size of buried Ge quantum dots.… more
Date: September 25, 2006
Creator: Lawniczak-Jablonska, K.; Demchenko, I. N.; Piskorska, E.; Wolska, A.; Talik, E.; Zakharov, D. N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Automated microscopy methods for measuring pyritic sulfur content of coal and determining degree of liberation of pyrite in coal: Final report

Description: The objective of this project is to develop an automated procedure, to be implemented in an IBAS image analyzer, to determine size, shape and degree of liberation of pyrite particles in a coal matrix. This procedure is to work in real time conditions and with minimal intervention from the operator. Our approach is to create from the original microscopic image a three level image with the following components: epoxy, coal macerals and pyrite to simplify the calculations. Enhancing the original i… more
Date: July 25, 1987
Creator: Chaparro, L.F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fusion target analysis by quantitative scanning electron microscopy

Description: Recent developments in computer based systems for quantitative x-ray microanalysis, 4 Pi surface examination, Auger electron spectroscopy and Backscattered Microtopography measurement have extended the Scanning Electron Microscope's applications in ICF target development and production.
Date: September 25, 1979
Creator: Ward, C.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Synthesis and Characterization of Porous Hydroxyapatite and Hydroxyapatite Coatings

Description: A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using water-soluble compounds and then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously reported. R… more
Date: October 25, 2000
Creator: Nieh, T. G.; Choi, B. W. & Jankowski, Alan Frederic
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Carbon Nanotube-Based Permeable Membranes: A Platform for Studying Nanofluidics

Description: A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Nitrogen flow measurements of a nanoporous silicon nitride membrane, fabricat… more
Date: May 25, 2004
Creator: Holt, J K; Park, H G; Noy, A; Huser, T; Eaglesham, D & Bakajin, O
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fabrication of a Carbon Nanotube-Embedded Silicon Nitride Membrane for Studies of Nanometer-Scale Mass Transport

Description: A membrane consisting of multiwall carbon nanotubes embedded in a silicon nitride matrix was fabricated for fluid mechanics studies on the nanometer scale. Characterization by tracer diffusion and scanning electron microscopy suggests that the membrane is free of large voids. An upper limit to the diffusive flux of D{sub 2}O of 2.4x10-{sup 8} mole/m{sup 2}-s was determined, indicating extremely slow transport. By contrast, hydrodynamic calculations of water flow across a nanotube membrane of si… more
Date: August 25, 2004
Creator: Holt, J K; Noy, A; Huser, T; Eaglesham, D & Bakajin, O
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Solid state chemistry of rare earth oxides. Technical progress report, 1974--1975. [High-resolution electron optical methods at 3 A resolution]

Description: Electron microscope images obtained at about 3A resolution for Pr/sub 7/O/sub 12/ (and isomorphous Zr/sub 3/Sc/sub 4/O/sub 12/) are in excellent agreement with calculated images based upon the structure determined separately by total profile neutron powder diffraction analysis. The image calculation programs establish the efficacy of lattice image interpretation in structural terms for these types of related phases whose structures are as yet beyond conventional means to determine. Such images … more
Date: June 25, 1975
Creator: Eyring, LeRoy; Summerville, Edward & Skarnulis, A. Jerome
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Quantitative tunneling spectroscopy of nanocrystals

Description: The proposed goals of this collaborative work were to systematically characterize the electronic structure and dynamics of 3-dimensional metal and semiconducting nanocrystals using scanning tunneling microscopy/spectroscopy (STM/STS) and ballistic electron emission spectroscopy (BEES). This report describes progress in the spectroscopic work and in the development of methods for creating and characterizing gold nanocrystals. During the grant period, substantial effort also was devoted to the de… more
Date: May 25, 2007
Creator: First, Phillip N; Whetten, Robert L & Schaaff, T Gregory
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Domain-wall oscillations studies by time-resolved soft x-ray mircorscopy

Description: Fast magnetization dynamics in the micro- and nanometer regime are an interesting field of research. On these length scales magnetic structures can be designed to contain a single vortex or a single domain wall. Both size and speed of these patterns are of great interest in todays research for prospective non-volatile data storage devices. Especially the possibility to move domain-walls by spin-polarized current gained a lot of interest. Magnetic configurations can be imaged by soft X-ray magne… more
Date: March 25, 2009
Creator: Bocklage, L.; Kruger, B.; Eiselt, R.; Bolte, M.; Fischer, P. & Meier, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Characterization and Detection of Biological Weapons with Atomic Force Microscopy

Description: Critical gaps exist in our capabilities to rapidly characterize threat agents which could be used in attacks on facilities and military forces. DNA-based PCR and immunoassay-based techniques provide unique identification of species, strains and protein signatures of pathogens. However, differentiation between naturally occurring and weaponized bioagents and the identification of formulation signatures are beyond current technologies. One of the most effective and often the only definitive means… more
Date: September 25, 2006
Creator: Malkin, A J; Plomp, M; Leighton, T J & McPherson, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Defect reduction in (11-20) a-plane GaN by two step epitaxiallateral overgrowth

Description: We report a two-step growth method to obtain uniformly coalesced epitaxial lateral overgrown a-plane GaN by metal-organic chemical vapor deposition (MOCVD). By obtaining a large wing height to width aspect ratio in the first step followed by enhanced lateral growth in the second step via controlling the growth temperature, we reduced the tilt angle between the advancing Ga-polar and N-polar wings for improved properties. Transmission electron microscopy (TEM) showed that the threading dislocati… more
Date: November 25, 2006
Creator: Ni, X.; Ozgur, U.; Fu, Y.; Biyikii, N.; Morkoc, H. & Liliental-Weber, Z.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Single Electron Tunneling

Description: Financial support for this project has led to advances in the science of single-electron phenomena. Our group reported the first observation of the so-called ''Coulomb Staircase'', which was produced by tunneling into ultra-small metal particles. This work showed well-defined tunneling voltage steps of width e/C and height e/RC, demonstrating tunneling quantized on the single-electron level. This work was published in a now well-cited Physical Review Letter. Single-electron physics is now a maj… more
Date: July 25, 2005
Creator: Ruggiero, Steven T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Thermodynamic Analysis Of Pure And Impurity Doped Pentaerythritol Tetranitrate Crystals Grown At Room Temperature

Description: Pentaerythritol tetranitrate (PETN) powders are used to initiate other explosives. During long-term storage, changes in powder properties can cause changes in the initiation performance. Changes in the morphology and surface area of aging powders are observed due to sublimation and growth of PETN crystals through coarsening mechanisms, (e.g. Ostwald ripening, sintering, etc.). In order to alleviate the sublimation of PETN crystals under service conditions, stabilization methods such as thermal … more
Date: May 25, 2006
Creator: Pitchimani, R.; Zheng, W.; Simon, S.; Hope-Weeks, L.; Burnham, A. K. & Weeks, B. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A system for combined three-dimensional morphological and molecular analysis of thick tissue specimens

Description: We present a new system for simultaneous morphological and molecular analysis of thick tissue samples. The system is composed of a computer assisted microscope and a JAVA-based image display, analysis and visualization program that allows acquisition, annotation, meaningful storage, three-dimensional reconstruction and analysis of structures of interest in thick sectioned tissue specimens. We describe the system in detail and illustrate its use by imaging, reconstructing and analyzing two compl… more
Date: April 25, 2002
Creator: Fernandez-Gonzalez, Rodrigo; Jones, Arthur; Garcia-Rodriguez, Enrique; Yuan Chen, Ping; Idica, Adam; Lockett, Stephen J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Characterization of high-power lithium-ion cells-performance and diagnostic analysis

Description: Lithium-ion cells, with graphite anodes and LiNi0.8Co0.15Al0.05O2 cathodes, were cycled for up to 1000 cycles over different ranges of SOC and temperatures. The decline in cell performance increases with the span of SOC and temperature during cycling. Capacity fade was caused by a combination of the loss of cycleable Li and degradation of the cathode. The room temperature anodes showed SEI compositions and degrees of graphite disorder that correlated with the extent of the Li consumption, which… more
Date: November 25, 2003
Creator: Striebel, K. A.; Shim, J.; Kostecki, R.; Richardson, T. J.; Ross, P. N.; Song, X. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Inversion domains in AlN grown on (0001) sapphire

Description: Al-polarity inversion domains formed during AlN layer growth on (0001) sapphire were identified using transmission electron microscopy (TEM). They resemble columnar inversion domains reported for GaN films grown on (0001) sapphire. However, for AlN, these columns have a V-like shape with boundaries that deviate by 2 {+-} 0.5{sup o} from the c-axis. TEM identification of these defects agrees with the post-growth surface morphology as well as with the microstructure revealed by etching in hot aqu… more
Date: August 25, 2003
Creator: Jasinski, J.; Liliental-Weber, Z.; Paduano, Q. S. & Weyburne, D. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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INVESTIGATIONS OF CARBIDES AS CATHODES FOR THERMIONIC SPACE REACTORS. Quarterly Progress Report for the Period Ending May 31, 1963

Description: Two long-term test cells were fabricated and tested. One was loaded with a 30 UC--70 ZrC sample and the other with a 90 UC--10 ZrC samrple. The rates of vaporization of these samaples in vacuum were determined both in the absence and in the presence of a Ni anode maintained at 983 deg K with an electrode spacirig of 20 mils, hr order to set the baseline values. Measurement of the rates of vaporization of these samples under these conditions in the presence of Cs vapor at a pressure of about 1.8… more
Date: September 25, 1963
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Diffusion and precipitation of inert gases in metals. Final report

Description: The behavior of inert gases, particularly helium, in metals was studied in aluminum, copper, niobium and stainless steel. Emphasis was upon characterizing the state of helium in the metals and upon following the kinetics of precipitation and coalescence. Experimental techniques that are, in most cases, new to studies of inert gases in metals were employed. These include low- temperature specific heat, precision lattice parameter measurement, internal friction, computer simulation, and residual … more
Date: September 25, 1973
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Macroscopic Superlattices of CdSe Colloidal Nanocrystals: Appearance and Optical Properties

Description: Two and three dimensional assemblies of colloidal nanocrystals (NCs) have been of great interest during recent years [1-3]. While size-dependent optical and electronic properties of isolated particles are particularly important for fundamental research, studies of their ordered assemblies provide a transition path to the engineering of materials and devices for future practical applications. Assemblies of NCs of different materials, such as semiconductors, metals and metal oxides, have been rep… more
Date: March 25, 2004
Creator: Zaitseva, N; Manna, L; Leon, F; Gerion, D; Saw, C & Galli, G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Synthesis of High Surface Area Alumina Aerogels without the Use of Alkoxide Precursors

Description: Alumina aerogels were prepared through the addition of propylene oxide to aqueous or ethanolic solutions of hydrated aluminum salts, AlCl{sub 3} {center_dot} 6H{sub 2}O or Al(NO{sub 3}){sub 3} {center_dot} 9H{sub 2}O, followed by drying with supercritical CO{sub 2}. This technique affords low-density (60-130 kg/m{sup 3}), high surface area (600-700 m{sup 2}/g) alumina aerogel monoliths without the use of alkoxide precursors. The dried alumina aerogels were characterized using elemental analysis… more
Date: June 25, 2004
Creator: Baumann, T. F.; Gash, A. E.; Chinn, S. C.; Sawvel, A. M.; Maxwell, R. S. & Satcher, J. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fabrication of Luminescent Nanostructures by Dip-Pen Nanolithography

Description: We used a combination of dip-pen nanolithography and scanning optical confocal microscopy to fabricate and visualize luminescent nanoscale patterns of various materials on glass substrates. We show that this method can be used successfully to push the limits of dip-pen nanolithography down to controlled deposition of single molecules. We also demonstrate that this method is able to create and visualize protein patterns on surfaces. Finally, we show that our method can be used to fabricate polym… more
Date: June 25, 2002
Creator: Noy, A; Miller, A E; Klare, J E; Weeks, B L; Woods, B W & DeYoreo, J J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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