Advantages of a soft protective layer for good signal-to-noise ratio proton radiographs in high debris environments (open access)

Advantages of a soft protective layer for good signal-to-noise ratio proton radiographs in high debris environments

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Date: December 21, 2010
Creator: Le Galloudec, N. R.; Cobble, J.; Nelson, S. L.; Merwin, A.; Paudel, Y.; Shrestha, I. et al.
Object Type: Article
System: The UNT Digital Library
Market Trial: Selling Off-Grid Lighting Products in Rural Kenya (open access)

Market Trial: Selling Off-Grid Lighting Products in Rural Kenya

In this study, we performed a market trial of off-grid LED lighting products in Maai Mahiu, arural Kenyan town. Our goals were to assess consumer demand and consumer preferences with respect to off-grid lighting systems and to gain feedback from off-grid lighting users at the point of purchase and after they have used to products for some time.
Date: June 21, 2010
Creator: Tracy, Jennifer; Alstone, Peter; Jacobson, Arne & Mills, Evan
Object Type: Report
System: The UNT Digital Library
Memory-bit selection and recording by rotating fields in vortex-core cross-point architecture (open access)

Memory-bit selection and recording by rotating fields in vortex-core cross-point architecture

In one of our earlier studies [Appl. Phys. Lett. 92, 022509 (2008)], we proposed a concept of robust information storage, recording and readout, which can be implementaed in nonvolatile magnetic random-access memories and is based on the energetically degenerated twofold ground states of vortex-core magnetizations. In the present study, we experimentally demonstrate reliable memory-bit selection and information recording in vortex-core cross-point architecture, specifically using a two-by-two vortex-state disk array. In order to efficiently switch a vortex core positioned at the intersection of crossed electrodes, two orthogonal addressing electrodes are selected, and then two Gaussian pulse currents of optimal pulse width and time delay are applied. Such tailored pulse-type rotating magnetic fields which occurs only at the selected intersection is prerequisite for a reliable memory-bit selection and low-power-consumption recording of information in the existing cross-point architecture.
Date: October 21, 2010
Creator: Yu, Young-Sang; Jung, Hyunsung; Lee, Ki-Suk; Fischer, Peter & Kim, Sang-Koog
Object Type: Article
System: The UNT Digital Library
Making the Standard Candle: A study of how the progenitor white dwarf modulates the peak luminosity of type Ia supernovae (open access)

Making the Standard Candle: A study of how the progenitor white dwarf modulates the peak luminosity of type Ia supernovae

The goals of the proposed research as stated in the proposal were to: • Build a suite of one-dimensional initial models of different metallicities and central densities. • Using the improved flame capturing scheme, simulate the explosion of a white dwarf with embedded Lagrangian tracer particles, and post-process the thermal histories of the tracers to reconstruct the nucleosynthesis of the explosion. • Survey the effects of a changing progenitor metallicity on the isotopic yields. Of particular interest is 1) whether the linear relation between the mass of 56Ni synthesized and the pro- genitor metallicity is moderated by the effect of electron captures in the core; and 2) how a varying central density alters the relation between metallicity and 56Ni mass. • Using these results, examine how the observed metallicity distribution would affect the brightness distribution of SNe Ia and the isotopic ratios about the Fe-peak.
Date: January 21, 2010
Creator: Brown, Edward F
Object Type: Report
System: The UNT Digital Library
An Assessment of Molecular Dynamic Force Fields for Silica for Use in Simulating Laser Damage Mitigation (open access)

An Assessment of Molecular Dynamic Force Fields for Silica for Use in Simulating Laser Damage Mitigation

We compare force fields (FF's) that have been used in molecular dynamic (MD) simulations of silica in order to assess their applicability for use in simulating IR-laser damage mitigation. Although pairwise FF?s obtained by fitting quantum mechanical calculations such as the BKS and CHIK potentials have been shown to reproduce many of the properties of silica including the stability of silica polymorphs and the densification of the liquid, we show that melting temperatures and fictive temperatures are much too high. Softer empirical force fields give liquid and glass properties at experimental temperatures but may not predict all properties important to laser mitigation experiments.
Date: October 21, 2010
Creator: Soules, T F; Gilmer, G H; Matthews, M J; Stolken, J S & Feit, M D
Object Type: Article
System: The UNT Digital Library
Development of tools and techniques for momentum compression of fast rare isotopes (open access)

Development of tools and techniques for momentum compression of fast rare isotopes

As part of our past research and development work, we have created and developed the LISE++ simulation code [Tar04, Tar08]. The LISE++ package was significantly extended with the addition of a Monte Carlo option that includes an option for calculating ion trajectories using a Taylor-series expansion up to fifth order, and implementation of the MOTER Monte Carlo code [Kow87] for ray tracing of the ions into the suite of LISE++ codes. The MOTER code was rewritten from FORTRAN into C++ and transported to the MS-Windows operating system. Extensive work went into the creation of a user-friendly interface for the code. An example of the graphical user interface created for the MOTER code is shown in the left panel of Figure 1 and the results of a typical calculation for the trajectories of particles that pass through the A1900 fragment separator are shown in the right panel. The MOTER code is presently included as part of the LISE++ package for downloading without restriction by the worldwide community. The LISE++ was extensively developed and generalized to apply to any projectile fragment separator during the early phase of this grant. In addition to the inclusion of the MOTER code, other important additions to …
Date: November 21, 2010
Creator: Morrissey, David J.; Sherrill, Bradley M. & Tarasov, Oleg
Object Type: Report
System: The UNT Digital Library
Bridging silyl groups in sigma-bond metathesis and [1, 2] shifts. An experimental and computational study of the reaction between cerium metallocenes and MeOSiMe3 (open access)

Bridging silyl groups in sigma-bond metathesis and [1, 2] shifts. An experimental and computational study of the reaction between cerium metallocenes and MeOSiMe3

The reaction of Cp'2CeH (Cp' = 1,2,4-(Me3C)3C5H2 ) with MeOSiMe3 gives Cp'2CeOMe and HSiMe3 and the reaction of the metallacycle, Cp'[(Me3C)2C5H2C(Me) 2CH2]Ce, with MeOSiMe3 yields Cp'2CeOCH2SiMe3, formed from hypothetical Cp'2CeCH2OSiMe3 by a [1, 2] shift also known as a silyl-Wittig rearrangement. Although both cerium products are alkoxides, they are formed by different pathways. DFT calculations on the reaction of the model metallocene, Cp2CeH, and MeOSiMe3 show that the lowest energy pathway is a H for OMe exchange at Ce that occurs by way of a sigma-bond metathesis transition state as SiMe3 exchanges partners. The formation of Cp2CeOCH2SiMe3 occurs by way of a low activation barrier [1, 2]shift of the SiMe3 group in Cp2CeCH2OSiMe3. Calculations on a model metallacycle, Cp[C5H4C(Me)2CH2]Ce, show that the metallacycle favors CH bond activation over sigma-bond metathesis involving the transfer of the SiMe3 group in good agreement with experiment. The sigma-bond metathesis involving the transfer of SiMe3 and the [1, 2]shift of SiMe3 reactions have in common a pentacoordinate silicon at the transition states. A molecular orbital analysis illustrates the connection between these two Si-O bond cleavage reactions and traces the reason why they occur for a silyl but not for an alkyl group to the difference …
Date: April 21, 2010
Creator: Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile & Andersen, Richard
Object Type: Article
System: The UNT Digital Library
The status of open heavy flavor production at RHIC (open access)

The status of open heavy flavor production at RHIC

We discuss the calculation of open heavy flavor cross sections at RHIC and describe how the semileptonic decays of charm and bottom quarks can be separated.
Date: December 21, 2010
Creator: Vogt, R
Object Type: Article
System: The UNT Digital Library
INDEPENDENT VERIFICATION SURVEY REPORT OPERABLE UNIT-1 LANDFILL TRENCHES, MIAMISBURG CLOSURE PROJECT (open access)

INDEPENDENT VERIFICATION SURVEY REPORT OPERABLE UNIT-1 LANDFILL TRENCHES, MIAMISBURG CLOSURE PROJECT

INDEPENDENT VERIFICATION SURVEY REPORT FOR THE OPERABLE UNIT-1 LANDFILL TRENCHES, MIAMISBURG CLOSURE PROJECT, MIAMISBURG, OHIO DCN: 0468-SR-03-0
Date: July 21, 2010
Creator: Adams, W.C.
Object Type: Report
System: The UNT Digital Library
618-10 Burial Ground VPU Nonintrusive Characterization Process and Data Collection Workshop (open access)

618-10 Burial Ground VPU Nonintrusive Characterization Process and Data Collection Workshop

This report presents the nonintrusive characterization measurement results for the 618-10 Burial Ground and provides a general assessment of the estimated dose, isotopic concentrations, and bounding transuranic radionuclide inventories for the 618-10 vertical pipe units and trenches, based on interpretation of data from a system of in situ radiological multi-detector probes.
Date: December 21, 2010
Creator: Khabir, S.
Object Type: Report
System: The UNT Digital Library
Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2009 Progress Report (open access)

Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2009 Progress Report

Pacific Northwest National Laboratory (PNNL) has been conducting research for the United States Department of Energy, Energy Efficiency Renewable Energy, Biomass Program to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). This research has involved the screening of potential catalysts, and optimization of the more promising ones, using laboratory scale reactors. During 2009, the main goal of the testing program focused on optimizing selected supported catalysts containing rhodium (Rh) and manganese (Mn). Optimization involved examining different total concentrations and atomic ratios of Rh and Mn as well as that of the more promising promoters (Ir and Li) identified in the earlier screening studies. Evaluation of catalyst performance focused on attaining improvements with respect to the space-time-yield and converted carbon selectivity to C2+ oxygenates, with additional consideration given to the fraction of the oxygenates that were C2+ alcohols.
Date: December 21, 2010
Creator: Gerber, Mark A.; Gray, Michel J.; Stevens, Don J.; White, J. F. & Rummel, Becky L.
Object Type: Report
System: The UNT Digital Library
Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry An ENERGY STAR(R) Guide for Energy and Plant Managers (open access)

Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry An ENERGY STAR(R) Guide for Energy and Plant Managers

Energy is an important cost factor in the U.S iron and steel industry. Energy efficiency improvement is an important way to reduce these costs and to increase predictable earnings, especially in times of high energy price volatility. There are a variety of opportunities available at individual plants in the U.S. iron and steel industry to reduce energy consumption in a cost-effective manner. This Energy Guide discusses energy efficiency practices and energy-efficient technologies that can be implemented at the component, process, facility, and organizational levels. A discussion of the structure, production trends, energy consumption, and greenhouse gas emissions of the iron and steel industry is provided along with a description of the major process technologies used within the industry. Next, a wide variety of energy efficiency measures are described. Many measure descriptions include expected savings in energy and energy-related costs, based on case study data from real-world applications in the steel and related industries worldwide. Typical measure payback periods and references to further information in the technical literature are also provided, when available. The information in this Energy Guide is intended to help energy and plant managers in the U.S. iron and steel industry reduce energy consumption and greenhouse gas emissions …
Date: October 21, 2010
Creator: Worrell, Ernst; Blinde, Paul; Neelis, Maarten; Blomen, Eliane & Masanet, Eric
Object Type: Report
System: The UNT Digital Library
Direct observation of imprinted antiferromagnetic vortex state in CoO/Fe/Ag(001) disks (open access)

Direct observation of imprinted antiferromagnetic vortex state in CoO/Fe/Ag(001) disks

In magnetic thin films, a magnetic vortex is a state in which the magnetization vector curls around the center of a confined structure. A vortex state in a thin film disk, for example, is a topological object characterized by the vortex polarity and the winding number. In ferromagnetic (FM) disks, these parameters govern many fundamental properties of the vortex such as its gyroscopic rotation, polarity reversal, core motion, and vortex pair excitation. However, in antiferromagnetic (AFM) disks, though there has been indirect evidence of the vortex state through observations of the induced FM-ordered spins in the AFM disk, they have never been observed directly in experiment. By fabricating single crystalline NiO/Fe/Ag(001) and CoO/Fe/Ag(001) disks and using X-ray Magnetic Linear Dichroism (XMLD), we show direct observation of the vortex state in an AFM disk of AFM/FM bilayer system. We observe that there are two types of AFM vortices, one of which has no analog in FM structures. Finally, we show that a frozen AFM vortex can bias a FM vortex at low temperature.
Date: December 21, 2010
Creator: Wu, J.; Carlton, D.; Park, J. S.; Meng, Y.; Arenholz, E.; Doran, A. et al.
Object Type: Article
System: The UNT Digital Library
Somatic genomic variations in extra-embryonic tissues (open access)

Somatic genomic variations in extra-embryonic tissues

In the mature chorion, one of the membranes that exist during pregnancy between the developing fetus and mother, human placental cells form highly specialized tissues composed of mesenchyme and floating or anchoring villi. Using fluorescence in situ hybridization, we found that human invasive cytotrophoblasts isolated from anchoring villi or the uterine wall had gained individual chromosomes; however, chromosome losses were detected infrequently. With chromosomes gained in what appeared to be a chromosome-specific manner, more than half of the invasive cytotrophoblasts in normal pregnancies were found to be hyperdiploid. Interestingly, the rates of hyperdiploid cells depended not only on gestational age, but were strongly associated with the extraembryonic compartment at the fetal-maternal interface from which they were isolated. Since hyperdiploid cells showed drastically reduced DNA replication as measured by bromodeoxyuridine incorporation, we conclude that aneuploidy is a part of the normal process of placentation potentially limiting the proliferative capabilities of invasive cytotrophoblasts. Thus, under the special circumstances of human reproduction, somatic genomic variations may exert a beneficial, anti-neoplastic effect on the organism.
Date: May 21, 2010
Creator: Weier, Jingly F.; Ferlatte, Christy & Weier, Heinz-Ulli G.
Object Type: Report
System: The UNT Digital Library
Quarkonia as a multi-purpose tool (open access)

Quarkonia as a multi-purpose tool

Quarkonia can be a very useful tool for understanding the medium in which they are produced and pass through. However, their usefulness as a tool depends on how well certain aspects of their behavior in cold matter are understood.
Date: December 21, 2010
Creator: Vogt, R
Object Type: Article
System: The UNT Digital Library

U.S. Fuel Cell Electric Vehicle Demonstration Project 2010 Status Update

This presentation summarizes U.S. Fuel Cell Electric Vehicle Demonstration Project 2010 Status Update.
Date: October 21, 2010
Creator: Wipke, K.; Sprik, S.; Kurtz, J. & Ramsden, T.
Object Type: Presentation
System: The UNT Digital Library
Data Quality Assessment Report for the Remedial Investigation of Hanford Site Releases to the Columbia River, Hanford Site, Washington (open access)

Data Quality Assessment Report for the Remedial Investigation of Hanford Site Releases to the Columbia River, Hanford Site, Washington

This report summarizes the results of the data quality assessment that was performed on the analytical data generated in connection with the 2008/2009 surface water, sediment, and soil data collection; groundwater upwelling investigation sample collection; and fish tissue sample collection.
Date: September 21, 2010
Creator: Hulstrom, L. C.
Object Type: Report
System: The UNT Digital Library

Durability of Poly (Methyl Methacrylate) Lenses Used in Concentrating Photovoltaics

This presentation reports the findings of NREL's screen test to characterize the durability of poly (methyl methacrylate) lenses used in concentrated photovoltaics.
Date: October 21, 2010
Creator: Miller, D.; Gedvilas, L.; To, B.; Kennedy, C. & Kurtz, S.
Object Type: Presentation
System: The UNT Digital Library
Key Physical Mechanisms in Nanostructured Solar Cells (open access)

Key Physical Mechanisms in Nanostructured Solar Cells

The objective of the project was to study both theoretically and experimentally the excitation, recombination and transport properties required for nanostructured solar cells to deliver energy conversion efficiencies well in excess of conventional limits. These objectives were met by concentrating on three key areas, namely, investigation of physical mechanisms present in nanostructured solar cells, characterization of loss mechanisms in nanostructured solar cells and determining the properties required of nanostructured solar cells in order to achieve high efficiency and the design implications.
Date: July 21, 2010
Creator: Bremner, Stephan
Object Type: Report
System: The UNT Digital Library
Analysis of Radioactive Releases During Proposed Demolition Activities for the 224-U and 224-UA Buildings - Addendum (open access)

Analysis of Radioactive Releases During Proposed Demolition Activities for the 224-U and 224-UA Buildings - Addendum

A post-demolition modeling analysis is conducted that compares during-demolition atmospheric concentration monitoring results with modeling results based on the actual meteorological conditions during the demolition activities. The 224-U and 224-UA Buildings that were located in the U-Plant UO3 complex in the 200 West Area of the Hanford Site were demolished during the summer of 2010. These facilities converted uranyl nitrate hexahydrate (UNH), a product of Hanford’s Plutonium-Uranium Extraction (PUREX) Plant, into uranium trioxide (UO3). This report is an addendum to a pre-demolition emission analysis and air dispersion modeling effort that was conducted for proposed demolition activities for these structures.
Date: December 21, 2010
Creator: Napier, Bruce A.; Rishel, Jeremy P.; Droppo, James G.; Joyce, Kevin E. & Strom, Daniel J.
Object Type: Report
System: The UNT Digital Library
AVNG as a Test Case for Cooperative Design (open access)

AVNG as a Test Case for Cooperative Design

Designing a measurement system that might be used in a nuclear facility is a challenging, if not daunting, proposition. The situation is made more complicated when the system needs to be designed to satisfy the disparate requirements of a monitoring and a host party - a relationship that could prove to be adversarial. The cooperative design of the elements of the AVNG (Attribute Verification with Neutrons and Gamma Rays) system served as a crucible that exercised the possible pitfalls in the design and implementation of a measurement system that could be used in a host party nuclear facility that satisfied the constraints of operation for both the host and monitoring parties. Some of the issues that needed to be addressed in the joint design were certification requirements of the host party and the authentication requirements of the monitoring party. In this paper the nature of the problem of cooperative design will be introduced. The details of cooperative design revolve around the idiosyncratic nature of the adversarial relationship between the parties involved in a possible measurement regime, particularly if measurements on items that may contain sensitive information are being pursued. The possibility of an adversarial interaction is more likely if an …
Date: May 21, 2010
Creator: Luke, S J
Object Type: Article
System: The UNT Digital Library
Aerosol-Assisted Solid Debris Collection for the National Ignition Facility (open access)

Aerosol-Assisted Solid Debris Collection for the National Ignition Facility

The National Ignition Facility (NIF) has been completed and has made its first shots on-target. While upcoming experiments will be focused on achieving ignition, a variety of subsequent experiments are planned for the facility, including measurement of cross sections, astrophysical measurements, and investigation of hydrodynamic instability in the target capsule. In order to successfully execute several of these planned experiments, the ability to collect solid debris following a NIF capsule shot will be required. The ability to collect and analyze solid debris generated in a shot at the National Ignition Facility (NIF) will greatly expand the number of nuclear reactions studied for diagnostic purposes. Currently, reactions are limited to only those producing noble gases for cryogenic collection and counting with the Radchem Apparatus for Gas Sampling (RAGS). The radchem solid collection diagnostic has already been identified by NIF to be valuable for the determination and understanding of mix generated in the target capsule's ablation. LLNL is currently developing this solid debris collection capability at NIF, and is in the stage of testing credible designs. Some of these designs explore the use of x-ray generated aerosols to assist in collection of solid debris. However, the variety of harsh experimental conditions this …
Date: May 21, 2010
Creator: Nelson, S. L.; Shaughnessy, D. A.; Moody, K. J.; Ivanov, V. V.; Astanovitskiy, A. L.; Lewis, L. A. et al.
Object Type: Article
System: The UNT Digital Library
Radiochemistry as a (rho)R Diagnostic with the RAGS Gas Collection System (open access)

Radiochemistry as a (rho)R Diagnostic with the RAGS Gas Collection System

Radiochemical diagnostic techniques such as gas-phase capsule debris analysis may prove to be successful methods for establishing the success or failure of ignition experiments at the National Ignition Facility (NIF). Samples in the gas phase offer the most direct method of collection by simply pumping out the large target chamber following a NIF shot. The target capsules will be prepared with dopants which will produce radioactive noble gas isotopes upon activation with neutrons. We have designed and constructed the Radchem Apparatus for Gas Sampling (RAGS) in order to collect post-shot gaseous samples for NIF capsule diagnostics. The design of RAGS incorporates multiple stages intended to purify, transfer, and count the radioactive decays from gaseous products synthesized in NIF experiments. At the moment the dopant of choice is {sup 124}Xe, which will undergo (n,{gamma}) and (n, 2n) reactions to produce {sup 125}Xe and {sup 123}Xe. The half-lives of each are on the order of multiple hours and are suitable for long-term gamma-counting. These isotopes and the rest of the gases evolved in a NIF shot will be drawn through the NIF turbo pumps, past the temporarily shuttered cryo pumps (to aid our collection efficiency), and towards the first main portion of …
Date: May 21, 2010
Creator: Nelson, S. L.; Shaughnessy, D. A.; Schneider, D. H.; Stoeffl, W.; Moody, K. J.; Cerjan, C. et al.
Object Type: Article
System: The UNT Digital Library
Proceedings of the 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies (open access)

Proceedings of the 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

These proceedings contain papers prepared for the Monitoring Research Review 2010: Ground-Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2010 in Orlando, Florida,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, National Science Foundation (NSF), Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.
Date: September 21, 2010
Creator: Wetovsky, Marvin A. & Patterson, Eileen F.
Object Type: Article
System: The UNT Digital Library