Fermi level stabilization energy in group III-nitrides (open access)

Fermi level stabilization energy in group III-nitrides

Energetic particle irradiation is used to systematically introduce point defects into In{sub 1-x}Ga{sub x}N alloys over the entire composition range. Three types of energetic particles (electrons, protons, and {sup 4}He{sup +}) are used to produce a displacement damage dose spanning five decades. In InN and In-rich InGaN the free electron concentration increases with increasing irradiation dose but saturates at a sufficiently high dose. The saturation is due to Fermi level pinning at the Fermi Stabilization Energy (E{sub FS}), which is located at 4.9 eV below the vacuum level. Electrochemical capacitance-voltage (ECV) measurements show that the pinning of the surface Fermi energy at E{sub FS} is also responsible for the surface electron accumulation in as-grown InN and In-rich InGaN alloys. The results are in agreement with the amphoteric defect model that predicts that the same type of native defects are responsible for the Fermi level pinning in both cases.
Date: January 7, 2005
Creator: Li, S. X.; Yu, K. M.; Wu, J.; Jones, R. E.; Walukiewicz, W.; AgerIII, J. W. et al.
Object Type: Article
System: The UNT Digital Library
''The control of lignin synthesis'' (open access)

''The control of lignin synthesis''

In this project we tested the hypothesis that regulation of the synthesis of lignin in secondary xylem cells in conifer trees involves the transport of glucosylated lignin monomers to the wall of xylem cells, followed by de-glucosylation in the cell wall by monolignol-specific glucosidase enzymes, which activates the monomers for lignin polymerization. The information we gathered is relevant to the fundamental understanding of how trees make wood, and to the applied goal of more environmentally friendly pulp and paper production. We characterized the complete genomic structure of the Coniferin-specific Beta-glucosidase (CBG) gene family in the conifers loblolly pine (Pinus taeda) and lodgepole pine (Pinus contorta), and partial genomic sequences were obtained in several other tree species. Both pine species contain multiple CBG genes which raises the possibility of differential regulation, perhaps related to the multiple roles of lignin in development and defense. Subsequent projects will need to include detailed gene expression studies of each gene family member during tree growth and development, and testing the role of each monolignol-specific glucosidase gene in controlling lignin content.
Date: April 7, 2005
Creator: Carlson, John E.
Object Type: Report
System: The UNT Digital Library
ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT (open access)

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.
Date: April 7, 2005
Creator: Nieder-Westermann, G.H.
Object Type: Report
System: The UNT Digital Library
Generalized weak turbulence theory (open access)

Generalized weak turbulence theory

None
Date: October 7, 2005
Creator: Yoon, Peter H.
Object Type: Report
System: The UNT Digital Library
2004 Sensory Transduction in Microorganisms Gordon Research Conference-January 11-16, 2004 (open access)

2004 Sensory Transduction in Microorganisms Gordon Research Conference-January 11-16, 2004

Research into the mechanisms involved in the sensing and responses of microorganisms to changes in their environment is currently very active in a large number of laboratories in the US, Europe, Japan, and Israel. A wide range of eukaryotic and prokaryotic species are being studies with regard to their sensing of chemical changes, light and redox signal and intercellular signaling, leading either to changes in motile behavior, gene expression or development. It has become increasingly apparent that the mechanisms involved in development have application in higher organisms while the sensing systems in bacteria are involved in a very wide range of physiological traits, from pathogenicity, through to biofilm formation. This is an area where a wide range of state of the art tools have been used and developed over the past few decades. Approaches include behavioral studies, electro-physiology, genetics, molecular biology, structural biology, biophysics and single molecule microscopy, immunocytochemistry and molecular and mathematical modeling, all of this helped by the large number of bacterial and eukaryotic microbial genome sequences now available. The central goal of this meeting is to bring together investigators using this wide range of approaches and different systems to compare data, share ideas and approaches and seeks …
Date: January 7, 2005
Creator: Storm, Judith Armitage Carlyle
Object Type: Article
System: The UNT Digital Library
Gas Storage Technology Consortium (open access)

Gas Storage Technology Consortium

None
Date: September 7, 2005
Creator: Morrison, Joel L.
Object Type: Report
System: The UNT Digital Library
An Examination of Avoided Costs in Utah (open access)

An Examination of Avoided Costs in Utah

The Utah Wind Working Group (UWWG) believes there are currently opportunities to encourage wind power development in the state by seeking changes to the avoided cost tariff paid to qualifying facilities (QFs). These opportunities have arisen as a result of a recent renegotiation of Pacificorp's Schedule 37 tariff for wind QFs under 3 MW, as well as an ongoing examination of Pacificorp's Schedule 38 tariff for wind QFs larger than 3 MW. It is expected that decisions made regarding Schedule 38 will also impact Schedule 37. Through the Laboratory Technical Assistance Program (Lab TAP), the UWWG has requested (through the Utah Energy Office) that LBNL provide technical assistance in determining whether an alternative method of calculating avoided costs that has been officially adopted in Idaho would lead to higher QF payments in Utah, and to discuss the pros and cons of this method relative to the methodology recently adopted under Schedule 37 in Utah. To accomplish this scope of work, I begin by summarizing the current method of calculating avoided costs in Utah (per Schedule 37) and Idaho (the ''surrogate avoided resource'' or SAR method). I then compare the two methods both qualitatively and quantitatively. Next I present Pacificorp's four …
Date: January 7, 2005
Creator: Bolinger, Mark & Wiser, Ryan
Object Type: Report
System: The UNT Digital Library
Antimicrobial Properties of Diamondlike Carbon-Silver-Platinum Nanocomposite Thin Films (open access)

Antimicrobial Properties of Diamondlike Carbon-Silver-Platinum Nanocomposite Thin Films

Silver and platinum were incorporated within diamondlike carbon (DLC) thin films using a multicomponent target pulsed laser deposition process. Transmission electron microscopy of the DLC-silver and DLC-platinum composite films reveals that the metals self-assemble into particulate nanocomposite structures. Nanoindentation testing has shown that diamondlike carbon-silver films exhibit hardness and Young's modulus values of approximately 37 GPa and 333 GPa, respectively. DLC-silver-platinum films exhibited antimicrobial properties against Staphylococcus bacteria. Diamondlike carbon-biofunctional metal nanocomposite films have a variety of potential medical and antimicrobial applications.
Date: March 7, 2005
Creator: CHRISTOPHER, BERRY
Object Type: Article
System: The UNT Digital Library
Lignite Fuel Enhancement Progress Report (open access)

Lignite Fuel Enhancement Progress Report

This 3rd quarterly Technical Progress Report for the Lignite Fuel Enhancement Project summarizes activities from January 1st through March 31st of 2005. It also summarizes the subsequent purchasing activity and final dryer/process design.
Date: June 7, 2005
Creator: Bullinger, Charles
Object Type: Report
System: The UNT Digital Library
Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy (open access)

Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy

Medical application of boron neutron capture therapy (BNCT) has been significantly hindered by the slow development of boron drug-targeting methodologies for the selective delivery of high boron concentration sto malignant cells. We have successfully sought to fill this need by creating liposomes suitable as in vivo boron delivery vehicles for BNCT. Delivery of therapeutic quantities of boron to tumors in murine models has been achieved with small unilamellar boron-rich liposomes. Subsequently, attempts have been made to improve delivery efficiency of liposomes encapsulating boron-containing water-soluble species into their hollow core by incorporating lipophilic boron compounds as addenda to the liposome bilayer, incorporating boron compounds as structural components of the bilayer (which however, poses the risk of sacrificing some stability), and combinations thereof. Regardless of the method, approximately 90% of the total liposome mass remains therapeutically inactive and comprised of the vehicle’s construction materials, while less than 5% is boron for neutron targeting. Following this laboratory's intensive study, the observed tumor specificity of certain liposomes has been attributed to their diminutive size of these liposomes (30-150 nm), which enables these small vesicles to pass through the porous, immature vasculature of rapidly growing tumor tissue. We surmised that any amphiphilic nanoparticle of suitable …
Date: April 7, 2005
Creator: Hawthorne, M. Frederick
Object Type: Report
System: The UNT Digital Library
Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals (open access)

Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals

This report describes the results of a program of research on the thermochemistry, spectroscopy and intramolecular relaxation dynamics of the combustion intermediate, HCO. We prepare this radical from acetaldehyde as a photo-precursor in a differentially pumped laser-ionization source quadrupole mass spectrometer. Using a multiresonant spectroscopic technique established in our laboratory, we select individual rotational states and overcome Franck-Condon barriers associated with neutral-to-cation geometry changes to promote transitions to individual autoionizing series and state-resolved ionization thresholds. Systematic analysis of rotational structure and associated lineshapes provide experimental insight on autoionization dynamics as input for theoretical modeling. Extrapolation of series, combined with direct threshold-photoelectron detection, yield precise ionization potentials that constitute an important contribution to the thermochemical base of information on HCO.
Date: September 7, 2005
Creator: Grant, Edward R.
Object Type: Report
System: The UNT Digital Library
Simulating Electron Clouds in Heavy-Ion Accelerators (open access)

Simulating Electron Clouds in Heavy-Ion Accelerators

Contaminating clouds of electrons are a concern for most accelerators of positive-charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly-, weakly-, and un-magnetized. They describe their approach to such self-consistency, and in particular a scheme for interpolating between full-orbit (Boris) and drift-kinetic particle pushes that enables electron time steps long compared to the typical gyro period in the magnets. They present tests and applications: simulation of electron clouds produced by three different kinds of sources indicates the sensitivity of the cloud shape to the nature of the source; first-of-a-kind self-consistent simulation of electron-cloud experiments on the High-Current Experiment (HCX) at Lawrence Berkeley National Laboratory, in which the machine can be flooded with electrons released by impact of the ion beam and an end plate, demonstrate the ability to reproduce key features of the ion-beam phase space; and simulation of a two-stream instability of thin beams in a magnetic field demonstrates the ability of the large-timestep mover to accurately calculate the instability.
Date: April 7, 2005
Creator: Cohen, R. H.; Friedman, A.; Kireeff Covo, M.; Lund, S. M.; Molvik, A. W.; Bieniosek, F. M. et al.
Object Type: Article
System: The UNT Digital Library
Beryllium Sampling and Analysis Within the DOE Complex and Opportunities for Standardization (open access)

Beryllium Sampling and Analysis Within the DOE Complex and Opportunities for Standardization

Since the U. S. Department of Energy published the DOE Beryllium Rule, 10 CFR 850, in 1999, DOE sites have been required to measure beryllium on air filters and wipes for worker protection and for release of materials from beryllium-controlled areas. Measurements in the nanogram range on a filter or wipe are typically required. Industrial hygiene laboratories have applied methods from various analytical compendia, and a number of issues have emerged with sampling and analysis practices. As a result, a committee of analytical chemists, industrial hygienists, and laboratory managers was formed in November 2003 to address the issues. The committee developed a baseline questionnaire and distributed it to DOE sites and other agencies in the U.S. and U.K. The results of the questionnaire are presented in this paper. These results confirmed that a wide variety of practices were in use in the areas of sampling, sample preparation, and analysis. Additionally, although these laboratories are generally accredited by the American Industrial Hygiene Association there are inconsistencies in performance among accredited labs. As a result, there are significant opportunities for development of standard methods that could improve consistency. The current availabilities and needs for standard methods are further discussed in a companion …
Date: February 7, 2005
Creator: MICHAEL, BRISSON
Object Type: Article
System: The UNT Digital Library
Nevada Test Site Decontamination and Decommissioning Program History, Regulatory Framework, and Lessons Learned (open access)

Nevada Test Site Decontamination and Decommissioning Program History, Regulatory Framework, and Lessons Learned

Decontamination and Decommissioning (D&D) of radiologically and/or chemically contaminated facilities at the Nevada Test Site (NTS) are the responsibility of the Environmental Restoration (ER) Project. Facilities identified for D&D are listed in the Federal Facilities Agreement and Consent Order (FFACO) and closed under the Resource Conservation and Recovery Act process. This paper discusses the NTS D&D program, including facilities history, D&D regulatory framework, and valuable lessons learned.
Date: August 7, 2005
Creator: Kruzic, Michael R.; Morris, Patrick S. & Nelson, Jerel G.
Object Type: Article
System: The UNT Digital Library
Lignite Fuel Enhancement Progress Report (open access)

Lignite Fuel Enhancement Progress Report

The Design Team continued to conference this quarter. Their primary task during this timeframe was to finalize the dryer design based on information learned from the NDIC Pilot work and detailed design discussions at Barr offices in August. Heyl-Patterson was tasked with incorporating all comments and drafting drawings. They submitted a preliminary proposal which spawned detailed discussions about tube bundle, air locks, and fire suppression systems. The type of fire protection specified dictated the final structural arrangement. Three meetings were spent discussing the pro's and con's of suppression vs. ventilation systems. In the end, the dryer and bucket elevator will have suppression systems and the remaining equipment will be explosion vented. This is in agreement with GRE's current insurer, FM Global. Three inlet airlocks were reduced to two and four outlets were reduced to three. The inlet plenum was subdivided for greater flexibility and sparging air added in the outlet plenum. It was also decided to use bundles with varied material, diameter, and tube & fin spacing. This will be completed in an effort to identify for us which configuration has the best heat transfer characteristics using coal as the fluidizing medium. The dryer will also be delivered in four …
Date: February 7, 2005
Creator: Bullinger, Charles
Object Type: Report
System: The UNT Digital Library
Experimental Investigation of Radio-Turbulence Induced Diffusion -- Final Report (open access)

Experimental Investigation of Radio-Turbulence Induced Diffusion -- Final Report

The outcome of this research project suggests that the transport of radon in water is significantly greater than that predicted solely by molecular diffusion. The original study was related to the long term storage of {sup 226}Ra-bearing sand at the DOE Fernald site and determining whether a barrier of water covering the sand would be effective in reducing the emanation of {sup 222}Rn from the sand. Initial observations before this study found the transport of radon in water to be greater than that predicted solely by molecular diffusion. Fick's law on diffusion was used to model the transport of radon in water including the impact associated with radioactive decay. Initial measurements suggested that the deposition of energy in water associated with the radioactive decay process influences diffusion and enhances transport of radon. A multi-region, one-dimensional, steady-state transport model was used to analyze the movement of radon through a sequential column of air, water and air. An effective diffusion coefficient was determined by varying the thickness of the water column and measuring the time for transport of {sup 222}Rn through of the water barrier. A one-region, one-dimensional transient diffusion equation was developed to investigate the build up of radon at the …
Date: July 7, 2005
Creator: Spitz, H. B. & Usman, S.
Object Type: Report
System: The UNT Digital Library
Low Cost and Energy Efficient Methods for the Manufacture of Semi-Solid (SSM) Feedstock (open access)

Low Cost and Energy Efficient Methods for the Manufacture of Semi-Solid (SSM) Feedstock

The SSM Consortium (now ACRC) at WPI has been carrying out fundamental, pre-competitive research in SSM for several years. Current and past research (at WPI) has generated many results of fundamental and applied nature, which are available to the SSM community. These include materials characterization, yield stress effects, alloy development, rheological properties, process modeling/simulation, semi-solid slurry formation, etc. Alternative method to produce SSM slurries at lower processing costs and with reduced energy consumption is a critical need. The production of low cost SSM feedstock will certainly lead to a dramatic increase in the tonnage of castings produced by SSM, and will provide end users such as the transportation industry, with lighter, cheaper and high performance materials. In this program, the research team has addressed three critical issues in semi-solid processing. They are: (1) Development of low cost, reliable slurry-on-demand approaches for semi-solid processing; (2) Application of the novel permanent grain refining technology-SiBloy for the manufacture of high-quality SSM feedstock, and (3) Development of computational and modeling tools for semi-solid processing to enhance SSM process control. Salient results from these studies are summarized and detailed in our final technical report.
Date: November 7, 2005
Creator: Apelian, Diran; Pan, Qingyue & Makhlouf, Makhlouf
Object Type: Report
System: The UNT Digital Library
COMPARING EXTRACTIONS OF SIVERS FUNCTIONS. (open access)

COMPARING EXTRACTIONS OF SIVERS FUNCTIONS.

A comparison is given of the various recently published extractions of the Sivers functions from the HERMES and COMPASS data on single-transverse spin asymmetries in semi-inclusive deeply inelastic scattering.
Date: September 7, 2005
Creator: VOGELSANG, W.
Object Type: Article
System: The UNT Digital Library
CANISTER HANDLING FACILITY CRITICALITY SAFETY CALCULATIONS (open access)

CANISTER HANDLING FACILITY CRITICALITY SAFETY CALCULATIONS

This design calculation revises and updates the previous criticality evaluation for the canister handling, transfer and staging operations to be performed in the Canister Handling Facility (CHF) documented in BSC [Bechtel SAIC Company] 2004 [DIRS 167614]. The purpose of the calculation is to demonstrate that the handling operations of canisters performed in the CHF meet the nuclear criticality safety design criteria specified in the ''Project Design Criteria (PDC) Document'' (BSC 2004 [DIRS 171599], Section 4.9.2.2), the nuclear facility safety requirement in ''Project Requirements Document'' (Canori and Leitner 2003 [DIRS 166275], p. 4-206), the functional/operational nuclear safety requirement in the ''Project Functional and Operational Requirements'' document (Curry 2004 [DIRS 170557], p. 75), and the functional nuclear criticality safety requirements described in the ''Canister Handling Facility Description Document'' (BSC 2004 [DIRS 168992], Sections 3.1.1.3.4.13 and 3.2.3). Specific scope of work contained in this activity consists of updating the Category 1 and 2 event sequence evaluations as identified in the ''Categorization of Event Sequences for License Application'' (BSC 2004 [DIRS 167268], Section 7). The CHF is limited in throughput capacity to handling sealed U.S. Department of Energy (DOE) spent nuclear fuel (SNF) and high-level radioactive waste (HLW) canisters, defense high-level radioactive waste (DHLW), …
Date: April 7, 2005
Creator: Sanders, C.E.
Object Type: Report
System: The UNT Digital Library
Final Report on Grant DE-FG02-04ER63801: Damage Recognition, Protein Signaling and Fidelity of Base Excision Repair (open access)

Final Report on Grant DE-FG02-04ER63801: Damage Recognition, Protein Signaling and Fidelity of Base Excision Repair

Research funded by grant DE-FG02-04ER63801 focused on DNA hydration modeled by classical molecular dynamics (MD) simulation. The most important finding of our research was that oxidation of guanine, a ubiquitous DNA lesion caused by endogenous and environmental oxidative stress, changes DNA hydration in a way that increases the stability of the damage base pair.
Date: November 7, 2005
Creator: Miller, John H.
Object Type: Report
System: The UNT Digital Library
Downhole Power Generation and Wireless Communications for Intelligent Completions Applications (open access)

Downhole Power Generation and Wireless Communications for Intelligent Completions Applications

Tubel Tech has been working with the DoE Rocky Mountain test center to create a CRADA which will allow Tubel Tech to test its wireless gauge in a well at the test center. The CRADA agreement should be completed by the next quarter and Tubel Tech expects to perform the final test on this project during the next quarter as well. The wireless gauge has not been modified or upgraded during this report period.
Date: November 7, 2005
Creator: Tubel, Paul
Object Type: Report
System: The UNT Digital Library
Characterization of Microbial Communities in TCE-Contaminated Seep Zone Sediments (open access)

Characterization of Microbial Communities in TCE-Contaminated Seep Zone Sediments

Hundreds of sites across the United States contain trichloroethene (TCE) contamination, including the Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. Previous studies have indicated that microorganisms are capable of efficiently degrading TCE to nonhazardous end products. In this project, molecular and growth based methods were used for microbial characterization of a TCE impacted seepzone where TCE degradation is naturally occurring. The results from this work provide clear evidence that the SRB may play a significant role in TCE degradation along the Twin Lakes seepline.
Date: March 7, 2005
Creator: ROBIN, BRIGMON
Object Type: Article
System: The UNT Digital Library
Advanced Process Heater (open access)

Advanced Process Heater

The Roadmap for Process Heating Technology (March 16, 2001), identified the following priority R&D needs: Improved performance of high temperature materials; Improved methods for stabilizing low emission flames; Heating technologies that simultaneously reduce emissions, increase efficiency, and increase heat transfer. This Category I award entitled ''Proof of Concept of an Advanced Process Heater (APH) for Steel, Aluminum, and Petroleum Industries of the Future'' met the technical feasibility goals of: (1) Doubling the heat transfer rates (2) Improving thermal efficiencies by 20%, (3) Improving temperature uniformity by 100 degrees F and (4) simultaneously reducing NOx and CO2 emissions. The APH address EERE's mission priority of increasing efficiency/reducing fuel usage in energy intensive industries. One component of the APH, the SpyroCorTM, was commercialized by STORM Development's partner, Spinworks LLC. Over 2000 SpyrCorsTM were sold in 2004 resulting in 480 million BTU's of energy savings, 20% reduction in NOx and CO2 levels, and 9 jobs in N.W. Pennsylvania. A second component, the HeatCorTM, a low-cost high-temperature heat exchanger will be demonstrated by Spinworks in 2005 in preparation for commercial sales in 2006. The project occurred in the 21st Congressional District of Pennsylvania. Once fully commercialized, the APH energy savings potential is 339 trillion …
Date: March 7, 2005
Creator: Tom Briselden, Chris Parrish
Object Type: Report
System: The UNT Digital Library
Final Report on Activities Supported by Department of Energy Grant No. DE-FG02-02ER63397, 2002-August 31, 2005 (open access)

Final Report on Activities Supported by Department of Energy Grant No. DE-FG02-02ER63397, 2002-August 31, 2005

The grant supported four projects that involved professional development for teachers and enrichment programs for students from under-funded and under-served school districts. The projects involved long-term partnerships between Hampshire College and the districts. All projects were concerned with the effective implementation of inquiry-based science learning and its alignment with state and national curriculum and assessment standards. One project, The Collaboration for Excellence in Science Education (CESE), was designed to support research on the development of concepts in the physical sciences, specifically energy and waves. Extensive data from student interviews and written essays supported the neo-Piagetian hierarchical complexity theory of this area of conceptual development. New assessment techniques that can be used by teachers were also developed. The final report includes a full presentation of the methods and results of the research.
Date: September 7, 2005
Creator: Marquez, Madelaine & Stillings, Neil
Object Type: Report
System: The UNT Digital Library