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in subjects: "Microscopy"

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Surfaces and interfaces of ceramics and metals for period July 1988--June 1991

During this three-year grant period our research program has been both expanded in its scope and established more firmly on knowledge of the basic materials involved. New techniques have been brought into play and these have allowed a more complete understanding of the nature and form of the surfaces of the oxide ceramics. There have been several surprising developments. One is the discovery of surface superlattice structures on surfaces of oxide crystals of oxide crystals (MgO, Al{sub 2}O{sub … more

Date: December 31, 1991

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A design of experiment study of plasma sprayed alumina-titania coatings

An experimental study of the plasma spraying of alumina-titania powder is presented in this paper. This powder system is being used to fabricate heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Coating experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and t… more

Date: August 1, 1992

Creator: Steeper, T. J.; Varacalle, D. J. Jr.; Wilson, G. C.; Riggs, W. L. II; Rotolico, A. J. & Nerz, J. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Current titles

116 abstracts are presented of work done with the electron microscope. NCEM is a DOE-designated national user facility and is available at no charge to qualified researchers (assess is controlled by a steering committee).

Date: April 1, 1993

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Defect diffusion during annealing of low-energy ion-implanted silicon

We present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7x7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of … more

Date: March 8, 2000

Creator: Bedrossian, P J; Caturla, M-J & Diaz de la Rubia, T

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fabrication of a Carbon Nanotube-Embedded Silicon Nitride Membrane for Studies of Nanometer-Scale Mass Transport

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: Article

Partner: UNT Libraries Government Documents Department

open access

Transport and deposition of functionalized CdTe nanoparticles in saturated porous media

Comprehensive understanding of the transport and deposition of engineered nanoparticles (NPs) in subsurface is required to assess their potential negative impact on the environment. We studied the deposition behavior of functionalized quantum dot (QD) NPs (CdTe) in different types of sands (Accusand, ultrapure quartz, and iron-coated sand) at various solution ionic strengths (IS). The observed transport behavior in ultrapure quartz and iron-coated sand was consistent with conventional colloid d… more

Date: October 15, 2010

Creator: Torkzaban, S.; Wan, J.; Kim, Y.; Mulvihill, M. & Tokunaga, T. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Petrographic correlations and mathematical analysis of log signatures for clay identification

This report presents the results of correlation of log signature with information on distribution of the types and volumes of clays in the sandstone pore spaces determined from detailed CT-scan, XRD, SEM and thin section analyses of core samples from three sandstone reservoirs. The log signatures are then analyzed to determine if suitable mathematical/statistical parameter(s) could be calculated from the logs for identification of types and volumes of clays in sandstone reservoirs.

Date: April 1, 1992

Creator: Sharma, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Material properties limiting the performance of CZT gamma-ray detectors

CdZnTe (CZT) nuclear radiation detectors are advanced sensors that utilize innovative technologies developed for wide band-gap semiconductor industry and microelectronics. They open opportunities for new types of room-temperature operating, field deployable instruments that provide accurate identification of potential radiological threats and timely awareness for both the civilian and military communities. Room-temperature radiation detectors are an emerging technology that relies on the use of… more

Date: March 16, 2009

Creator: Bolotnikov, A. E.; Babalola, S.; Camarda, G. S.; Cui, Y.; Egarievwe, S. U.; Hossain, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Sensory Transduction in Microorganisms 2008 Gordon Research Conference (January 2008)

Research into the mechanisms involved in the sensing and responses of microorganisms to changes in their environments is currently very active in a large number of laboratories worldwide. An increasingly wide range of prokaryotic and eukaryotic species are being studied with regard to their sensing of diverse chemical and physical stimuli, including nutrients, toxins, intercellular signaling molecules, redox indicators, light, pressure, magnetic fields, and surface contact, leading to adaptive … more

Date: April 8, 2009

Creator: Stock, Ann M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Double patterning HSQ processes of zone plates for 10 nm diffraction limitedperformance

In e-beam lithography, fabrication of sub-20 nm dense structures is challenging. While there is a constant effort to develop higher resolution resist processes, the progress of increasing pattern density is slow. For zone plates, consisting of dense lines and spaces, the outermost zone width has been limited to slightly less than 20 nm due to effects such as low aerial image contrast, forward scattering, intrinsic resist resolution, and development issues. To circumvent these effects, we have s… more

Date: January 9, 2009

Creator: Chao, Weilun; Kim, Jihoon; Anderson, Erik H.; Fischer, Peter; Rekawa, Senajith & Attwood, David T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Data Summary for Nominal 350 ?m DUO2 Kernels

This document is a compilation of characterization data obtained on the nominal 350 {micro}m depleted uranium oxide kernels (DUO{sub 2}) produced by ORNL for the Advanced Gas Reactor Fuel Development and Qualification Program under task 3.1.2. Samples were riffled for analysis from a 100 g batch (designated as DUN350-1), which was riffled from the 3.4 kg composite lot of DUO{sub 2} kernels (designated as DUN350). Table 2-1 contains a summary of property measurements in comparison to the current… more

Date: September 1, 2004

Creator: Hunn, John D

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Interplay between intrinsic and stacking-fault magnetic domains in bi-layered manganites

We present a low temperature X-ray photoemission electron microscopy study of the bi-layered manganite compound La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} (BL-LSMO) to investigate the influence of stacking faults, which are structurally and magnetically different from the bi-layered host. In BL-LSMO small magnetic moment persists to T* = 300K, well above the Curie temperature of 120K (T{sub C}). Our magnetic images show that 3D stacking faults are responsible for the T* transition. Furthermore, cl… more

Date: September 11, 2012

Creator: Hossain, M. A; Burkhardt, Mark H.; Sarkar, S.; Ohldag, H.; Chuang, Y. D.; Scholl, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

UNDERSTANDING THE EFFECTS OF SURFACTANT ADDITION ON RHEOLOGY USING LASER SCANNING CONFOCAL MICROSCOPY

The effectiveness of three dispersants to modify rheology was examined using rheology measurements and laser scanning confocal microscopy (LSCM) in simulated waste solutions. All of the dispersants lowered the yield stress of the slurries below the baseline samples. The rheology curves were fitted reasonably to a Bingham Plastic model. The three-dimensional LSCM images of simulants showed distinct aggregates were greatly reduced after the addition of dispersants leading to a lowering of the yie… more

Date: May 8, 2007

Creator: White, T

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Molecular Mechanism of Bacterial Attachment to Fe(III)-Oxide Surfaces

To date, our studies have concentrated upon two aspects of the chemistry and architecture of the Shewanella outer membrane surface: the influence of terminal electron acceptor during anaerobic respiration, and the role that protein secretion systems play in determining the presence and chemistry of exopolymers. Using Shewanella oneidensis strain MR-1 and S. putrefaciens strain 200R as model organisms we have developed a microelectrophoresis approach to estimating cell mobility in solution over … more

Date: June 1, 2006

Creator: Neal, Andrew

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Stress Development and Relaxation in Al2O3 during Early StageOxidation of beta-NiAl

Using a glancing synchrotron X-ray beam (Advanced Photon Source, Beamline 12BM, Argonne National Laboratory), Debye-Scherrer diffraction patterns from thermally grown oxides on NiAl samples were recorded during oxidation at 1000 or 1100 C in air. The diffraction patterns were analyzed to determine strain and phase changes in the oxide scale as it developed and evolved. Strain was obtained from measurements of the elliptical distortion of the Debye-Scherrer rings, where data from several rings o… more

Date: April 20, 2005

Creator: Hou, P.Y.; Paulikas, A.P. & Veal, B.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dual Beam FIB for Imaging, Nano-Sectioning and Sample Preparation of Spores: Initial Results.

Results from the first use of Focused Ion Beam (FIB) technology to section Bacillus spores at LLNL in a dual-beam (electron and ion) instrument is presented and discussed. With the use of a dual-beam instrument, high resolution imaging of single spores using low voltage scanning electron microscopy followed by FIB sectioning, SEM imaging of internal structure of the same spore is demonstrated to be possible. Additionally, FIB is shown to be able to precisely micro-machine spores thus potentiall… more

Date: April 26, 2004

Creator: Wall, M A; Fluss, M J & Schaldach, C

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Optical Microscopy and Small-Angle Scattering Study of Porosity in Thermally Treated PBX 9501

Heat transfer and comlmstion properties of a high explosive (HE) are influenced by the HE microstructure. The development of voids and cracks in an HE system under the conditions of thermal loading can have a strong impact on the safety and reliability of a weapon system. The optical microscopy and small angle x-ray scattering (SAXS) techniques are useful tools for microstructural characterization. A combination of the tools allows lengthscales from hundreds of microns to tenths of nanometers t… more

Date: January 1, 2001

Creator: Mang, Joseph T.; Skidmore, Cary B.; Hjelm, Rex P.; Ricker, Thomas P. & Son, Steven F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Time-Resolved Imaging of Material Response Following Laser-Induced Breakdown in the Bulk and Surface of Fused Silica

Optical components within high energy laser systems are susceptible to laser-induced material modification when the breakdown threshold is exceeded or damage is initiated by pre-existing impurities or defects. These modifications are the result of exposure to extreme conditions involving the generation of high temperatures and pressures and occur on a volumetric scale of the order of a few cubic microns. The response of the material following localized energy deposition, including the timeline … more

Date: February 4, 2010

Creator: Raman, R N; Negres, R A; DeMange, P & Demos, S G

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PROBING STRESS EFFECTS IN SINGLE CRYSTAL ORGANIC TRANSISTORS BY SCANNING KELVIN PROBE MICROSCOPY

We report scanning Kelvin probe microscopy (SKPM) of single crystal difluoro bis(triethylsilylethynyl) anthradithiophene (diF-TESADT) organic transistors. SKPM provides a direct measurement of the intrinsic charge transport in the crystals independent of contact effects and reveals that degradation of device performance occurs over a time period of minutes as the diF-TESADT crystal becomes charged.

Date: June 11, 2010

Creator: Teague, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nano-crystal growth in cordierite glass ceramics studied with X-ray scattering

The development of monodisperse crystalline particles in cordierite glass doped with Cr3+ after a two-step heat treatment is elucidated by a combination of time-resolved small and wide angle x-ray scattering (SAXS/WAXS) experiments with electron microscopy. The effects of bulk and surface crystallization can clearly be distinguished, and the crystallization kinetics of the bulk phase is characterized. The internal pressure due to structural differences between the crystalline and amorphous phas… more

Date: January 16, 2009

Creator: Bras, Wim; Clark, Simon M.; Greaves, G. N.; Kunz, Martin; van Beek, W. & Radmilovic, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fracture Induced Sub-Band Absorption as a Precursor to Optical Damage on Fused Silica Surfaces

The optical damage threshold of indentation induced flaws on fused silica surfaces was explored. Mechanical flaws were characterized by laser damaged testing, SEM, optical, and photoluminescence microscopy. Localized polishing, chemical etching, and the control of indentation morphology were used to isolate the structural features which limit optical damage. A thin defect layer on fracture surfaces, including those smaller than the wavelength of visible light, was found to be the dominant sourc… more

Date: March 5, 2010

Creator: Miller, P E; Bude, J D; Suratwala, T I; Shen, N; Laurence, T A; Steele, W A et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Wettability and Prediction of Oil Recovery From Reservoirs Developed With Modern Drilling and Completion Fluids

We report on progress in three areas. In part one, the wetting effects of synthetic base oils are reported. Part two reports progress in understanding the effects of surfactants of known chemical structures, and part three integrates the results from surface and core tests that show the wetting effects of commercial surfactant products used in synthetic and traditional oil-based drilling fluids. An important difference between synthetic and traditional oil-based muds (SBM and OBM, respectively)… more

Date: May 1, 2004

Creator: Buckley, Jill S. & Morrow, Norman R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. … more

Date: December 19, 2004

Creator: Huh, Seong

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Stress Corrosion Crack Growth Rate Testing and Analytical Electron Microscopy of Alloy 600 as a Function of Pourbaix Space and Microstructure

Stress corrosion crack (SCC) growth rate tests and analytical electron microscopy (AEM) studies were performed over a broad range of environments and heat treatments of Alloy 600. This effort was conducted to correlate bulk environmental conditions such as pH and electrochemical potential (EcP) with the morphology of the SCC crack. Development of a library of AEM morphologies formed by SCC in different environments is an important step in identifying the conditions that lead to SCC in component… more

Date: October 4, 2000

Creator: Lewis, N.; Attanasio, S. A.; Morton, D. S. & Young, G. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department