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IRON-PHOSPHATE GLASS FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM
Technetium-99 (Tc-99) can bring a serious environmental threat because of its high fission yield, long half-life, and high solubility and mobility in the ground water. The present work investigated the immobilization of Tc-99 (surrogated by Re) by heat-treating mixtures of an iron-phosphate glass with 1.5 to 6 wt.% KReO{sub 4} at {approx}1000 C. The Re retention in the glass was as high as {approx}1.2 wt. % while the loss of Re by evaporation during melting was {approx}50%. Re was uniformly distributed within the glass. The normalized Re release by the 7-day Product Consistency Test was {approx}0.39 g/m{sup 2}, comparable with that in phosphate-bonded ceramics and borosilicate glasses. These results suggest that iron-phosphate glass can provide a good matrix for immobilizing Tc-99.
Date:
March 19, 2012
Creator:
AA, KRUGER; PR, HRMA; K, XU; J, CHOI; W, UM & J, HEO
Object Type:
Article
System:
The UNT Digital Library
STATUS OF THE DEVELOPMENT OF IN-TANK/AT-TANK SEPARATIONS TECHNOLOGIES FOR FOR HIGH-LEVEL WASTE PROCESSING FOR THE U.S. DEPARTMENT OF ENERGY
Within the U.S. Department of Energy's (DOE) Office of Technology Innovation and Development, the Office of Waste Processing manages a research and development program related to the treatment and disposition of radioactive waste. At the Savannah River (South Carolina) and Hanford (Washington) Sites, approximately 90 million gallons of waste are distributed among 226 storage tanks (grouped or collocated in 'tank farms'). This waste may be considered to contain mixed and stratified high activity and low activity constituent waste liquids, salts and sludges that are collectively managed as high level waste (HLW). A large majority of these wastes and associated facilities are unique to the DOE, meaning many of the programs to treat these materials are 'first-of-a-kind' and unprecedented in scope and complexity. As a result, the technologies required to disposition these wastes must be developed from basic principles, or require significant re-engineering to adapt to DOE's specific applications. Of particular interest recently, the development of In-tank or At-Tank separation processes have the potential to treat waste with high returns on financial investment. The primary objective associated with In-Tank or At-Tank separation processes is to accelerate waste processing. Insertion of the technologies will (1) maximize available tank space to efficiently support …
Date:
September 19, 2011
Creator:
Aaron, G. & Wilmarth, B.
Object Type:
Article
System:
The UNT Digital Library
A Change in the Optical Polarization Associated with a Gamma-Ray Flare in the Blazar 3C 279
It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma ({gamma})-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and {gamma}-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10{sup 5} gravitational radii.
Date:
August 19, 2011
Creator:
Abdo, A. A.
Object Type:
Article
System:
The UNT Digital Library
Fermi-LAT Discovery of GeV Gamma-ray Emission from the Young Supernova Remnant Cassiopeia A
We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2{sigma} above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W{sub CR} {approx_equal} (1-4) x 10{sup 49} erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B {ge} 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.
Date:
August 19, 2011
Creator:
Abdo, A. A.
Object Type:
Article
System:
The UNT Digital Library
The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data
We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called 'extra-galactic' diffuse {gamma}-ray emission (EGB). This component of the diffuse {gamma}-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic {gamma}-ray emission (DGE), the detected LAT sources and the solar {gamma}-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index {gamma} = 2.41 {+-} 0.05 and intensity, I(> 100 MeV) = (1.03 {+-} 0.17) x 10{sup -5} cm{sup -2} s{sup -1} sr{sup -1}, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.
Date:
August 19, 2011
Creator:
Abdo, A. A.
Object Type:
Article
System:
The UNT Digital Library
Descriptors for Pentane-2,4-dione and Its Derivatives
This article uses equations for partition coefficients of compounds from water and the gas phase to various solvents to obtain descriptors for pentane-2,4-dione and 21 of its derivatives.
Date:
August 19, 2017
Creator:
Abraham, M. H. (Michael H.) & Acree, William E. (William Eugene)
Object Type:
Article
System:
The UNT Digital Library
Oral History Interview with Diana Abrego, July 19, 2016
Diana Abrego talks about being a migrant worker in her early years. She also talks about living in the borderland; being of two worlds, both Mexico & the U.S. She also talks about Del Rio's San Felipe's barrio and the segregation. Some black/brown relations in San Felipe. Being in the brown berets in Del Rio.
Date:
July 19, 2016
Creator:
Abrego, Diana; Arionus, Steve & Sinta, Vinicio
Object Type:
Video
System:
The Portal to Texas History
Commentary on "Correlation of solubility of hexamethylene-1,6-bisthiosulphate disodium salt dihydrate versus dielectric constants of water + ethanol mixtures"
This article discusses the finding that Apelblat model equation coefficients are found to give calculated mole fractions that exceed unity for the solubility of hexamethylene-1,6-bisthiosulphate disodium salt dihydrate dissolved in binary aqueous-ethanol solvent mixtures.
Date:
May 19, 2017
Creator:
Acree, William E. (William Eugene) & Yang, Chunhui
Object Type:
Article
System:
The UNT Digital Library
Oral History Interview with Curtis Clerkley, July 19, 2016
Mr. Clerkley discussed his career as a local educator and the history of the black community in Corpus Christi
Date:
July 19, 2016
Creator:
Acuña-Gurrola, Moisés; Wall, James & Clerkley, Curtis
Object Type:
Video
System:
The Portal to Texas History
Oral History Interview with Arnold Gonzalez, June 19, 2016
Arnold Gonzales is an educator, former state legislator, assistant state land commissioner, Corpus Christi city councilman, and Navy veteran. He graduated from Ray High School and earned a degree in art from Texas A&M Kingsville and taught art in middle school. He won a Mott Fellowship and earned a Masters' and PhD from the University of Michigan. In his interview, he talked quite a bit about his history as a politician in Corpus Christi.
Date:
June 19, 2016
Creator:
Acuña-Gurrola, Moisés; Wall, James & Gonzales, Arnold
Object Type:
Video
System:
The Portal to Texas History
Oral History Interview with Esther Bonnilla Read, July 19, 2016
Interview with Esther Bonilla Read from Corpus Christi. In her interview, Ms. Read discusses growing up in segregated East Texas and Corpus Christi.
Date:
July 19, 2016
Creator:
Acuña-Gurrola, Moisés; Wall, James & Read, Esther Bonilla
Object Type:
Video
System:
The Portal to Texas History
Drug Related Corruption
This paper explores the relationship between the global drug trade and the corruption of government officials.
Date:
April 19, 2012
Creator:
Adams, Mark & Sahliyeh, Emile F.
Object Type:
Paper
System:
The UNT Digital Library
Drugs and Corruption [Presentation]
Presentation for the 2012 University Scholars Day at the University of North Texas discussing research on the relationship between the global drug trade and the corruption of government officials.
Date:
April 19, 2012
Creator:
Adams, Mark & Sahliyeh, Emile F.
Object Type:
Presentation
System:
The UNT Digital Library
Building Your Congregation Over the Long Haul - Things Learned After 33 Years with One Church
Lecture given Monday, September 19, 2011, 9:00 AM at Abilene Christian University: "There is a lot to consider in leading a church – leadership, growth, community, spiritual formation, outreach. All of us are still learning. Discover lessons learned from both successes and failures in leading a church."
Date:
September 19, 2011
Creator:
Adcox, Jimmy
Object Type:
Sound
System:
The Portal to Texas History
Lebanon: Background and U.S. Relations
This report provides an overview of Lebanese politics, recent events in Lebanon, and current issues in U.S.-Lebanon relations.
Date:
January 19, 2011
Creator:
Addis, Casey L.
Object Type:
Report
System:
The UNT Digital Library
U.S. Security Assistance to Lebanon
This report discusses key issues facing U.S. policy makers and members of Congress when considering U.S. security assistance in the context of U.S. policy toward Lebanon. These key issues include assessing the effectiveness of U.S. assistance programs, assessing overall U.S. policy toward Lebanon, and managing relations with other external actors.
Date:
January 19, 2011
Creator:
Addis, Casey L.
Object Type:
Report
System:
The UNT Digital Library
Design Methodology and Consideratios for NOVA 53 MHZ RF Cavities
The NO?A Experiment will construct a detector optimized for electron neutrino detection in the existing Neutrino at Main Injector (NuMI) beamline. This beamline is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. The cavities will operate at 53 MHz and three of them will be installed in the Recycler beamline. Thermal stability of the cavities is crucial since this affects the tuning. Results of finite element thermal and structural analysis involving the copper RF cavity will be presented.
Date:
May 19, 2010
Creator:
Ader, C. & Wildman, D.W.
Object Type:
Article
System:
The UNT Digital Library
Tank 26F-2F Evaporator Study
Tank 26F supernate sample was sent by Savannah River Remediation to Savannah River National Laboratory for evaporation test to help understand the underlying cause of the recent gravity drain line (GDL) pluggage during operation of the 2F Evaporator system. The supernate sample was characterized prior to the evaporation test. The evaporation test involved boiling the supernate in an open beaker until the density of the concentrate (evaporation product) was between 1.4 to 1.5 g/mL. It was followed by filtering and washing of the precipitated solids with deionized water. The concentrate supernate (or concentrate filtrate), the damp unwashed precipitated solids, and the wash filtrates were characterized. All the precipitated solids dissolved during water washing. A semi-quantitative X-ray diffraction (XRD) analysis on the unwashed precipitated solids revealed their composition. All the compounds with the exception of silica (silicon oxide) are known to be readily soluble in water. Hence, their dissolution during water washing is not unexpected. Even though silica is a sparingly water-soluble compound, its dissolution is also not surprising. This stems from its small fraction in the solids as a whole and also its relative freshness. Assuming similar supernate characteristics, flushing the GDL with water (preferably warm) should facilitate dissolution and …
Date:
December 19, 2012
Creator:
Adu-Wusu, K.
Object Type:
Report
System:
The UNT Digital Library
Finding Enough - Sabbath Keeping in the 21st Century
Lecture given Monday, September 19, 2011, 9:00 AM at Abilene Christian University: "Is everyday a whirlwind of activity? Are you so busy working for God that you no longer feel near God? It must be time for Sabbath. Join us as we explore the why and how of contemporary Sabbath keeping."
Date:
September 19, 2011
Creator:
Agnell, Cynthia
Object Type:
Sound
System:
The Portal to Texas History
CDMSlite: A Search for Low-Mass WIMPs using Voltage-Assisted Calorimetric Ionization Detection in the SuperCDMS Experiment
None
Date:
February 19, 2014
Creator:
Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Thakur, R. Basu; Bauer, D. A. et al.
Object Type:
Article
System:
The UNT Digital Library
Fresh Water Generation from Aquifer-Pressured Carbon Storage
Can we use the pressure associated with sequestration to make brine into fresh water? This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including reverse osmosis (RO) and nanofiltration (NF). Possible products are: Drinking water, Cooling water, and Extra aquifer space for CO{sub 2} storage. The conclusions are: (1) Many saline formation waters appear to be amenable to largely conventional RO treatment; (2) Thermodynamic modeling indicates that osmotic pressure is more limiting on water recovery than mineral scaling; (3) The use of thermodynamic modeling with Pitzer's equations (or Extended UNIQUAC) allows accurate estimation of osmotic pressure limits; (4) A general categorization of treatment feasibility is based on TDS has been proposed, in which brines with 10,000-85,000 mg/L are the most attractive targets; (5) Brines in this TDS range appear to be abundant (geographically and with depth) and could be targeted in planning future CCS operations (including site selection and choice of injection formation); and (6) The estimated cost of treating waters in the 10,000-85,000 mg/L TDS range is about half that for conventional seawater desalination, due to the anticipated pressure …
Date:
February 19, 2010
Creator:
Aines, R. D.; Wolery, T. J.; Bourcier, W. L.; Wolfe, T. & Haussmann, C.
Object Type:
Article
System:
The UNT Digital Library
Constraints on Dark Matter Models From a Fermi LAT Search for High-Energy Cosmic-Ray Electrons from the Sun
None
Date:
March 19, 2013
Creator:
Ajello, M.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R. et al.
Object Type:
Article
System:
The UNT Digital Library
A Dual Channel X-ray Spectrometer for Fast Ignition Research
A new Dual Channel Highly Ordered Pyrolytic Graphite (DC-HOPG) x-ray spectrometer was developed to study laser-generated electron beam transport. The instrument uses a pair of graphite crystals and has the advantage of simultaneously detecting self emission from low-Z materials in first diffraction order and high-Z materials in second order. The emissions from the target are detected using a pair of parallel imaging plates positioned in a such way that the noise from background is minimized and the mosaic focusing is achieved. Initial tests of the diagnostic on Titan laser (I {approx} 10{sup 20} W/cm{sup 2}, {tau} = 0.7 ps) show excellent signal-to-noise ratio (SNR) > 1000 for the low energy channel and SNR > 400 for the high energy channel.
Date:
April 19, 2010
Creator:
Akli, K. U.; Patel, P. K.; Van Maren, R.; Stephens, R. B.; Key, M. H.; Higginson, D. P. et al.
Object Type:
Article
System:
The UNT Digital Library
A Solid-State Nanosecond Beam Kicker Modulator Based on the DSRD Switch
A fast solid-state beam kicker modulator is under development at the SLAC National Accelerator Laboratory. The program goal is to develop a modulator that will deliver 4 ns, {+-}5 kV pulses to the ATF2 damping ring beam extraction kicker. The kicker is a 50 {Omega}, bipolar strip line, 60 cm long, fed at the downstream end and terminated at the upstream end. The bunch spacing in the ring is 5.6 ns, bunches are removed from the back end of the train, and there is a gap of 103.6 ns before the next train. The modulator design is based on an opening switch topology that uses Drift Step Recovery Diodes as the opening switches. The design and results of the modulator development are discussed. There are many applications that benefit from very fast high power switching. However, at MW power levels and nanosecond time scales, solid state options are limited. One option, the Drift Step Recovery Diode (DSRD) has been demonstrated as capable of blocking thousands of volts and switching in nanosecond to sub-nanosecond ranges. When used as an opening switch, the DSRD exhibits a very fast turn off transient. The process is described in detail by its pioneers in [5,6]. …
Date:
August 19, 2011
Creator:
Akre, R.; Benwell, A.; Burkhart, C.; Krasnykh, A.; Tang, T. & Kardo-Sysoev, A.
Object Type:
Article
System:
The UNT Digital Library