Discrete Dipole Approximation for Low-Energy Photoelectron Emission from NaCl Nanoparticles (open access)

Discrete Dipole Approximation for Low-Energy Photoelectron Emission from NaCl Nanoparticles

This work presents a model for the photoemission of electrons from sodium chloride nanoparticles 50-500 nm in size, illuminated by vacuum ultraviolet light with energy ranging from 9.4-10.9 eV. The discrete dipole approximation is used to calculate the electromagnetic field inside the particles, from which the two-dimensional angular distribution of emitted electrons is simulated. The emission is found to favor the particle?s geometrically illuminated side, and this asymmetry is compared to previous measurements performed at the Lawrence Berkeley National Laboratory. By modeling the nanoparticles as spheres, the Berkeley group is able to semi-quantitatively account for the observed asymmetry. Here however, the particles are modeled as cubes, which is closer to their actual shape, and the interaction of an emitted electron with the particle surface is also considered. The end result shows that the emission asymmetry for these low-energy electrons is more sensitive to the particle-surface interaction than to the specific particle shape, i.e., a sphere or cube.
Date: September 22, 2011
Creator: Berg, Matthew J.; Wilson, Kevin R.; Sorensen, Chris; Chakrabarti, Amit & Ahmed, Musahid
Object Type: Article
System: The UNT Digital Library
Syrian Refugee Admissions to the United States (open access)

Syrian Refugee Admissions to the United States

This report discusses the U.S.'s plans to admit Syrian and other refugees in FY2016 and beyond. The Obama Administration initially proposed an overall refugee ceiling of 75,000 for FY2016 and held consultations with Congress on that proposal, as required by law.
Date: September 22, 2015
Creator: Bruno, Andorra
Object Type: Report
System: The UNT Digital Library
Unauthorized Alien Students: Issues and "DREAM Act" Legislation (open access)

Unauthorized Alien Students: Issues and "DREAM Act" Legislation

Supporters of comprehensive immigration reform have urged the President and Congress to pursue reform legislation. While legislative action on comprehensive reform does not appear likely during the remainder of the 111th Congress, there may be an effort to enact a measure, commonly referred to as the "DREAM Act," to enable certain unauthorized alien students to legalize their status. Multiple bills have been introduced in recent Congresses to address the unauthorized student population. This report discusses the DREAM Act, the topic of unauthorized alien students in general, and other related legislation.
Date: September 22, 2010
Creator: Bruno, Andorra
Object Type: Report
System: The UNT Digital Library
Customer Choice and the Power Industry of the Future (open access)

Customer Choice and the Power Industry of the Future

This report will begin to explore the issues, discussing what forms a transition from today's electric power grid to a grid of the future could take, and suggest questions that Congress may want to address. The United States seems to be at a turning point in the history of the electric power sector, some have advocated for the electric utility industry model to be reinvented under a "Utility 2.0" paradigm, wherein the modern needs of society for electric power and services become the driving force behind utility investments.
Date: September 22, 2014
Creator: Campbell, Richard J.
Object Type: Report
System: The UNT Digital Library
EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS (open access)

EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS

Two formulations of EPDM elastomer, one substituting a UV stabilizer for the normal antioxidant in this polymer, and the other the normal formulation, were synthesized and samples of each were exposed to gamma irradiation in initially pure deuterium gas to compare their radiation stability. Stainless steel containers having rupture disks were designed for this task. After 130 MRad dose of cobalt-60 radiation in the SRNL Gamma Irradiation Facility, a significant amount of gas was created by radiolysis; however the composition indicated by mass spectroscopy indicated an unexpected increase in the total amount deuterium in both formulations. The irradiated samples retained their ductility in a bend test. No change of sample weight, dimensions, or density was observed. No change of the glass transition temperature as measured by dynamic mechanical analysis was observed, and most of the other dynamic mechanical properties remained unchanged. There appeared to be an increase in the storage modulus of the irradiated samples containing the UV stabilizer above the glass transition, which may indicate hardening of the material by radiation damage. Polymeric materials become damaged by exposure over time to ionizing radiation. Despite the limited lifetime, polymers have unique engineering material properties and polymers continue to be used …
Date: September 22, 2011
Creator: Clark, E.
Object Type: Report
System: The UNT Digital Library
Finding Quotes for Speeches: Fact Sheet (open access)

Finding Quotes for Speeches: Fact Sheet

This report provides sources for finding quotes. The resources are divided into three categories: (1) General Quotations, (2) Americana, and (3) Religion.
Date: September 22, 2015
Creator: Crane-Hirsch, Audrey C.
Object Type: Report
System: The UNT Digital Library
LITERATURE REVIEW OF BORIC ACID SOLUBILITY DATA (open access)

LITERATURE REVIEW OF BORIC ACID SOLUBILITY DATA

A new solvent system is being evaluated for use in the Modular Caustic-Side Solvent Extraction Unit (MCU) and in the Salt Waste Processing Facility (SWPF). The new system replaces the current dilute nitric acid strip solution with 0.01 M boric acid. This literature study is performed to determine if there is a potential for boric acid to crystallize in the lines with emphasis on the transfer lines to the Defense Waste Processing Facility. This report focuses on the aqueous phase chemistry of boric acid under conditions relevant to MCU and SWPF. Operating and transfer conditions examined for the purpose of this review include temperatures between 13 C (McLeskey, 2008) and 45 C (Fondeur, 2007) and concentrations from 0 to 3M in nitric acid as well as exposure of small amounts of entrained boric acid in the organic phase to the sodium hydroxide caustic wash stream. Experiments were also conducted to observe any chemical reactions and off-gas generation that could occur when 0.01 M boric acid solution mixes with 3 M nitric acid solution and vice versa. Based on the low concentration (0.01M) of boric acid in the MCU/SWPF strip acid and the moderate operating temperatures (13 C to 45 C), …
Date: September 22, 2011
Creator: Crapse, K. & Kyser, E.
Object Type: Report
System: The UNT Digital Library
City of Denton Texas 2020-21 annual program of services (open access)

City of Denton Texas 2020-21 annual program of services

The report provides an overview of the City of Denton’s budget process and budget documents. The City of Denton has prepared a budget designed to meet the highest standards of performance in municipal budgeting. This document provides a summary of all budgeted funds, including both revenue and expenditure summaries. Major budget documents, the budget process, and organization of the budget itself are described in this report.
Date: September 22, 2019
Creator: Denton. City of Denton
Object Type: Report
System: The Portal to Texas History
Progress on the NSTX Center Stack Upgrade (open access)

Progress on the NSTX Center Stack Upgrade

The National Spherical Torus Experiment (NSTX) will be upgraded to provide increased toroidal field, plasma current and pulse length. This involves the replacement of the so-called center stack, including the inner legs of the Toroidal Field (TF) coil, the Ohmic Heating (OH) coil, and the inner Poloidal Field (PF) coils. In addition the increased performance of the upgrade requires qualification of remaining existing components for higher loads. Initial conceptual design efforts were based on worst-case combinations of possible currents that the power supplies could deliver. This proved to be an onerous requirement and caused many of the outer coils support structures to require costly heavy reinforcement. This has led to the planned implementation of a Digital Coil Protection System (DCPS) to reduce design-basis loads to levels that are more realistic and manageable. As a minimum, all components must be qualified for the increase in normal operating loads with headroom. Design features and analysis efforts needed to meet the upgrade loading are discussed. Mission and features of the DCPS are presented.
Date: September 22, 2010
Creator: Dudek, L.; Chrzanowski, J.; Heitzenroeder, P.; Mangra, D.; Neumeyer, C.; Smith, M. et al.
Object Type: Article
System: The UNT Digital Library
U.S. Trade in Services: Trends and Policy Issues (open access)

U.S. Trade in Services: Trends and Policy Issues

This report provides background information and analysis on U.S. international trade in services. It analyzes policy issues before the United States, especially relating to negotiating international disciplines on trade in services and dealing complexities in measuring trade in services. The report also examines emerging issues and current negotiations.
Date: September 22, 2015
Creator: Fefer, Rachel F.
Object Type: Report
System: The UNT Digital Library
Chemical Species in the Vapor Phase of Hanford Double-Shell Tanks: Potential Impacts on Waste Tank Corrosion Processes (open access)

Chemical Species in the Vapor Phase of Hanford Double-Shell Tanks: Potential Impacts on Waste Tank Corrosion Processes

The presence of corrosive and inhibiting chemicals on the tank walls in the vapor space, arising from the waste supernatant, dictate the type and degree of corrosion that occurs there. An understanding of how waste chemicals are transported to the walls and the affect on vapor species from changing supernatant chemistry (e.g., pH, etc.), are basic to the evaluation of risks and impacts of waste changes on vapor space corrosion (VSC). In order to address these issues the expert panel workshop on double-shell tank (DST) vapor space corrosion testing (RPP-RPT-31129) participants made several recommendations on the future data and modeling needs in the area of DST corrosion. In particular, the drying of vapor phase condensates or supernatants can form salt or other deposits at the carbon steel interface resulting in a chemical composition at the near surface substantially different from that observed directly in the condensates or the supernatants. As a result, over the past three years chemical modeling and experimental studies have been performed on DST supernatants and condensates to predict the changes in chemical composition that might occur as condensates or supernatants equilibrate with the vapor space species and dry at the carbon steel surface. The experimental studies …
Date: September 22, 2010
Creator: Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W. & Boomer, Kayle D.
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF CRYSTALLINE CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES (open access)

DEVELOPMENT OF CRYSTALLINE CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

The Savannah River National Laboratory (SRNL) is developing crystalline ceramic waste forms to incorporate CS/LN/TM high Mo waste streams consisting of perovskite, hollandite, pyrochlore, zirconolite, and powellite phase assemblages. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase crystalline ceramics. Fiscal Year 2011 (FY11) activities included (i) expanding the compositional range by varying waste loading and fabrication of compositions rich in TiO{sub 2}, (ii) exploring the processing parameters of ceramics produced by the melt and crystallize process, (iii) synthesis and characterization of select individual phases of powellite and hollandite that are the target hosts for radionuclides of Mo, Cs, and Rb, and (iv) evaluating the durability and radiation stability of single and multi-phase ceramic waste forms. Two fabrication methods, including melting and crystallizing, and pressing and sintering, were used with the intent of studying phase evolution under various sintering conditions. An analysis of the XRD and SEM/EDS results indicates that the targeted crystalline phases of the FY11 compositions consisting of pyrochlore, perovskite, hollandite, zirconolite, and powellite were formed by both press and sinter and melt and crystallize processing methods. An evaluation of crystalline phase formation versus melt processing conditions …
Date: September 22, 2011
Creator: Fox, K. & Brinkman, K.
Object Type: Report
System: The UNT Digital Library
PRELIMINARY STUDY OF CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES (open access)

PRELIMINARY STUDY OF CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

The Savannah River National Laboratory (SRNL) developed a series of ceramic waste forms for the immobilization of Cesium/Lanthanide (CS/LN) and Cesium/Lanthanide/Transition Metal (CS/LN/TM) waste streams anticipated to result from nuclear fuel reprocessing. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase ceramics containing hollandite-type phases, perovskites (particularly BaTiO{sub 3}), pyrochlores, zirconolite, and other minor metal titanate phases. Identification of excess Al{sub 2}O{sub 3} via X-ray Diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) in the first series of compositions led to a Phase II study, with significantly reduced Al{sub 2}O{sub 3} concentrations and increased waste loadings. Three fabrication methodologies were used, including melting and crystallizing, pressing and sintering, and Spark Plasma Sintering (SPS), with the intent of studying phase evolution under various sintering conditions. XRD and SEM/EDS results showed that the partitioning of the waste elements in the sintered materials was very similar, despite varying stoichiometry of the phases formed. The Phase II compositions generally contained a reduced amount of unreacted Al{sub 2}O{sub 3} as identified by XRD, and had phase assemblages that were closer to the initial targets. Chemical composition measurements showed no significant issues …
Date: September 22, 2010
Creator: Fox, K.; Billings, A.; Brinkman, K. & Marra, J.
Object Type: Report
System: The UNT Digital Library
Generalized displacement correlation method for estimating stress intensity factors (open access)

Generalized displacement correlation method for estimating stress intensity factors

None
Date: September 22, 2011
Creator: Fu, P.; Johnson, S. M.; Settgast, R. R. & Carrigan, C. R.
Object Type: Article
System: The UNT Digital Library
Approaches for Addressing Risks in Reprocessing Facilities: An Assessment (open access)

Approaches for Addressing Risks in Reprocessing Facilities: An Assessment

N/A
Date: September 22, 2013
Creator: G., Martinez-Guridi; V., Mubayi & Bari, R. A.
Object Type: Article
System: The UNT Digital Library
The Disruption of Vessel-Spanning Bubbles with Sloped Fins in Flat-Bottom and 2:1 Elliptical-Bottom Vessels (open access)

The Disruption of Vessel-Spanning Bubbles with Sloped Fins in Flat-Bottom and 2:1 Elliptical-Bottom Vessels

Radioactive sludge was generated in the K-East Basin and K-West Basin fuel storage pools at the Hanford Site while irradiated uranium metal fuel elements from the N Reactor were being stored and packaged. The fuel has been removed from the K Basins, and currently, the sludge resides in the KW Basin in large underwater Engineered Containers. The first phase to the Sludge Treatment Project being led by CH2MHILL Plateau Remediation Company (CHPRC) is to retrieve and load the sludge into sludge transport and storage containers (STSCs) and transport the sludge to T Plant for interim storage. The STSCs will be stored inside T Plant cells that are equipped with secondary containment and leak-detection systems. The sludge is composed of a variety of particulate materials and water, including a fraction of reactive uranium metal particles that are a source of hydrogen gas. If a situation occurs where the reactive uranium metal particles settle out at the bottom of a container, previous studies have shown that a vessel-spanning gas layer above the uranium metal particles can develop and can push the overlying layer of sludge upward. The major concern, in addition to the general concern associated with the retention and release of …
Date: September 22, 2010
Creator: Gauglitz, Phillip A.; Buchmiller, William C.; Jenks, Jeromy WJ; Chun, Jaehun; Russell, Renee L.; Schmidt, Andrew J. et al.
Object Type: Report
System: The UNT Digital Library
Corporate Tax Reform: Issues for Congress (open access)

Corporate Tax Reform: Issues for Congress

This report provides an overview of corporate tax issues and discusses potential reforms in the context of these issues, with particular attention to some of the research concerning large behavioral responses and their implications for revenue and distribution. The first section reviews the size and history of the corporate income tax, and discusses an important issue that has been given little attention by those who propose deep cuts in the corporate tax: its role in preventing the use of the corporate form as a tax shelter by wealthy business owners. This section also discusses the potential effect of behavioral responses on corporate tax revenues. The second section examines the role of the corporate tax in contributing to a progressive tax system and discusses claims that the burden falls on workers. The third section reviews arguments relating to efficiency and revenue yield, and traditional criticisms of the corporate tax as one that causes important behavioral distortions. One aspect of this discussion is the question of how the tax might be viewed differently in a more global economy. The final section examines options for reform.
Date: September 22, 2017
Creator: Gravelle, Jane G.
Object Type: Report
System: The UNT Digital Library
Conventional Arms Transfers to Developing Nations, 2003-2010 (open access)

Conventional Arms Transfers to Developing Nations, 2003-2010

This report is prepared annually to provide Congress with official, unclassified, quantitative data on conventional arms transfers to developing nations by the United States and foreign countries for the preceding eight calendar years for use in its policy oversight functions. All agreement and delivery data in this report for the United States are government-to-government Foreign Military Sales (FMS) transactions. Similar data are provided on worldwide conventional arms transfers by all suppliers, but the principal focus is the level of arms transfers by major weapons suppliers to nations in the developing world.
Date: September 22, 2011
Creator: Grimmett, Richard F.
Object Type: Report
System: The UNT Digital Library
National Flood Insurance Program Borrowing Authority (open access)

National Flood Insurance Program Borrowing Authority

This report evaluates the National Flood Insurance Program (NFIP) borrowing authority to receive loans from the U.S. Department of the Treasury (Treasury), particularly in the context of major floods, and discusses the current financial situation of the NFIP as it begins to pay claims from Hurricanes Harvey and Irma.
Date: September 22, 2017
Creator: Horn, Diane P.
Object Type: Report
System: The UNT Digital Library
Biasing, Acquisition and Interpretation of a Dense Langmuir Probe Array in NSTX (open access)

Biasing, Acquisition and Interpretation of a Dense Langmuir Probe Array in NSTX

A dense array of 99 Langmuir probes has been installed in the lower divertor region of the National Spherical Torus Experiments (NSTX). This array is instrumented with a system of elec- tronics that allows flexibility in the choice of probes to bias as well as the type of measurement (including standard swept, single probe, triple probe and operation as passive floating potential and scrape-off-layer (SOL) current monitors). The use of flush-mounted probes requires careful inter- pretation. The time dependent nature of the SOL makes swept-probe traces difficult to interpret. To overcome these challenges, the single- and triple-Langmuir probe signals are used in comple- mentary fashion to determine the temperature and density at the probe location. A comparison to mid-plane measurements is made. Work is supported by DOE contracts DE-AC02-09CHI1466 and DE-PS02-07ER07-29.
Date: September 22, 2010
Creator: Jaworski, M. A.; Kallman, J.; Kaita, R.; Kugel, H.; LeBlanc, B.; Marsala, R. et al.
Object Type: Report
System: The UNT Digital Library
Microscopic Motion of Liquid Metal Plasma Facing Components In A Diverted Plasma (open access)

Microscopic Motion of Liquid Metal Plasma Facing Components In A Diverted Plasma

Liquid metal plasma facing components (PFCs) have been identified as an alternative material for fusion plasma experiments. The use of a liquid conductor where significant magnetic fields are present is considered risky, with the possibility of macroscopic fluid motion and possible ejection into the plasma core. Analysis is carried out on thermoelectric magnetohydrodynamic (TEMHD) forces caused by temperature gradients in the liquid-container system itself in addition to scrape-off-layer currents interacting with the PFC from a diverted plasma. Capillary effects at the liquid-container interface will be examined which govern droplet ejection criteria. Stability of the interface is determined using linear stability methods. In addition to application to liquidmetal PFCs, thin film liquidmetal effects have application to current and future devices where off-normal events may liquefy portions of the first wall and other plasma facing components.
Date: September 22, 2010
Creator: Jaworski, M. A.; Morley, N. B.; Abrams, T; Kaita, R; Kallman, J; Kugel, H et al.
Object Type: Report
System: The UNT Digital Library
The Federal Food Safety System: A Primer (open access)

The Federal Food Safety System: A Primer

The combined efforts of the food industry and the regulatory agencies often are credited with making the U.S. food supply among the safest in the world. Nonetheless, many food-related health issues persist. At issue is whether the current U.S. regulatory system has the resources and structural organization to protect consumers from these dangers. Also at issue is whether the federal food safety laws themselves, first enacted in the early 1900s, have kept pace with the significant changes that have occurred in the food production, processing, and marketing sectors since then.
Date: September 22, 2010
Creator: Johnson, Renée
Object Type: Report
System: The UNT Digital Library
Implementation of the FDA Food Safety Modernization Act (FSMA, P.L. 111-353) (open access)

Implementation of the FDA Food Safety Modernization Act (FSMA, P.L. 111-353)

This report documents the scheduled timeline for action on selected FDA Food Safety Modernization Act (FSMA) provisions, as specified in the enacted law, and FDA-reported actions taken to date, based on available FDA press releases and publicly available progress reports.
Date: September 22, 2014
Creator: Johnson, Renée
Object Type: Report
System: The UNT Digital Library
The National Wild and Scenic Rivers System: A Brief Overview (open access)

The National Wild and Scenic Rivers System: A Brief Overview

This report gives a brief overview of the designation, management, and funding of rivers in the National Wild and Scenic Rivers System.
Date: September 22, 2015
Creator: Johnson, Sandra L. & Comay, Laura B.
Object Type: Report
System: The UNT Digital Library