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Commercial Real Estate Losses and the Risk to Financial Stability (open access)

Commercial Real Estate Losses and the Risk to Financial Stability

February report of the U.S. Congressional Oversight Panel describing their activities and findings regarding the state of commercial real estate and the impact of real estate losses to the stability of the economy.
Date: February 11, 2010
Creator: United States. Congressional Oversight Panel.
System: The UNT Digital Library
Influence of Incision Location on Transmitter Loss, Healing, Incision Lengths, Suture Retention, and Growth of Juvenile Chinook Salmon (open access)

Influence of Incision Location on Transmitter Loss, Healing, Incision Lengths, Suture Retention, and Growth of Juvenile Chinook Salmon

In this study, conducted by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers, Portland District, we measured differences in survival and growth, incision openness, transmitter loss, wound healing, and erythema among abdominal incisions on the linea alba, lateral and parallel to the linea alba (muscle-cutting), and following the underlying muscle fibers (muscle-sparing). A total of 936 juvenile Chinook salmon were implanted with both Juvenile Salmon Acoustic Tracking System transmitters (0.43 g dry) and passive integrated transponder tags. Fish were held at 12°C (n = 468) or 20°C (n = 468) and examined once weekly over 98 days. We found survival and growth did not differ among incision groups or between temperature treatment groups. Incisions on the linea alba had less openness than muscle-cutting and muscle-sparing incisions during the first 14 days when fish were held at 12°C or 20°C. Transmitter loss was not different among incision locations by day 28 when fish were held at 12°C or 20°C. However, incisions on the linea alba had greater transmitter loss than muscle-cutting and muscle-sparing incisions by day 98 at 12°C. Results for wound closure and erythema differed among temperature groups. Results from our study will be used to improve …
Date: May 11, 2010
Creator: Panther, Jennifer L.; Brown, Richard S.; Gaulke, Greggory L.; Woodley, Christa M. & Deters, Katherine A.
System: The UNT Digital Library
Storage Viability and Optimization Web Service (open access)

Storage Viability and Optimization Web Service

Non-residential sectors offer many promising applications for electrical storage (batteries) and photovoltaics (PVs). However, choosing and operating storage under complex tariff structures poses a daunting technical and economic problem that may discourage potential customers and result in lost carbon and economic savings. Equipment vendors are unlikely to provide adequate environmental analysis or unbiased economic results to potential clients, and are even less likely to completely describe the robustness of choices in the face of changing fuel prices and tariffs. Given these considerations, researchers at Lawrence Berkeley National Laboratory (LBNL) have designed the Storage Viability and Optimization Web Service (SVOW): a tool that helps building owners, operators and managers to decide if storage technologies and PVs merit deeper analysis. SVOW is an open access, web-based energy storage and PV analysis calculator, accessible by secure remote login. Upon first login, the user sees an overview of the parameters: load profile, tariff, technologies, and solar radiation location. Each parameter has a pull-down list of possible predefined inputs and users may upload their own as necessary. Since the non-residential sectors encompass a broad range of facilities with fundamentally different characteristics, the tool starts by asking the users to select a load profile from a …
Date: October 11, 2010
Creator: Stadler, Michael; Marnay, Christ; Lai, Judy; Siddiqui, Afzal; Limpaitoon, Tanachai; Phan, Trucy et al.
System: The UNT Digital Library
Technology Summary Advancing Tank Waste Retrieval and Processing (open access)

Technology Summary Advancing Tank Waste Retrieval and Processing

This technology overview provides a high-level summary of technologies being investigated and developed by Washington River Protection Solutions (WRPS) to advance Hanford Site tank waste retrieval and processing. Technology solutions are outlined, along with processes and priorities for selecting and developing them.
Date: August 11, 2010
Creator: Sams, T. L. & Mendoza, R. E.
System: The UNT Digital Library
Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance (open access)

Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance

Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4 h after 100 d irradiation by a 1-GeV proton beam, is consistent with studies at several accelerator facilities and with adopted hands-on maintenance dose rate limits. Monte Carlo simulations verify this result for protons and extend studies to heavy ion beam losses in drift-tube linac and superconducting linac accelerating structures. The studies indicate that the 1 W/m limit imposed on uncontrolled beam losses for high-energy proton beams might be relaxed for heavy ion beams. These studies further suggest that using the ratio of neutrons produced by a heavy ion beam to neutrons produced by a proton beam along with the dose rate from the proton beam (for thin-target scenarios) should allow an estimate of the dose rates expected from heavy ion beam losses.
Date: September 11, 2010
Creator: Ronningen, Reginald M. & Remec, Igor
System: The UNT Digital Library
Report on Electrochemical Corrosion Testing for Tank 241-AN-106 Using 2009 Sampling Campaign Grab Samples (open access)

Report on Electrochemical Corrosion Testing for Tank 241-AN-106 Using 2009 Sampling Campaign Grab Samples

Based on an ENRAF waste surface measurement taken February 1, 2009, double-shell tank (DST) 24l-AN-l06 (AN-106) contained approximately 278.98 inches (793 kgal) of waste. A zip cord measurement from the tank on February 1, 2009, indicated a settled solids layer of 9l.7 inches in height (280 kgal). The supernatant layer in February 2009, by difference, was approximately 187 inches deep (514 kgal). Laboratory results from AN-l06 February 1, 2009 (see Table 2) grab samples indicated the supernatant was below the chemistry limit that applied at the time as identified in HNF-SD-WM-TSR-006, 'Tank Farms Technical Safety Requirements', Administrative Control (AC) 5.16, 'Corrosion Mitigation Controls.' The limits have since been removed from the Technical Safety Requirements (TSR) and are captured in OSD-T-15l-00007, 'Operating Specifications for the Double-Shell Storage Tanks.' Problem evaluation request WRPS-PER-2009-0218 was submitted February 9,2009, to document the finding that the supernatant chemistry for grab samples taken from the middle and upper regions of the supernatant was noncompliant with the chemistry control limits. The lab results for the samples taken from the bottom region of the supernatant met AC 5.16 limits.
Date: May 11, 2010
Creator: Wyrwas, R. B.
System: The UNT Digital Library
Analysis of Failed and Nickel-coated 3093 Beam Clamp Components at the East Tennessee Technology Park (ettp) (open access)

Analysis of Failed and Nickel-coated 3093 Beam Clamp Components at the East Tennessee Technology Park (ettp)

The U.S. Department of Energy and its contractor, Bechtel Jacobs Company (BJC), are undertaking a major effort to clean up the former gaseous diffusion facility (K-25) located in Oak Ridge, TN. The decontamination and decommissioning activities require systematic removal of contaminated equipment and machinery followed by demolition of the buildings. As part of the cleanup activities, a beam clamp, used for horizontal life lines (HLLs) for fall protection, was discovered to be fractured during routine inspection. The beam clamp (yoke and D-ring) was a component in the HLL system purchased from Reliance Industries LLC. Specifically, the U-shaped stainless steel yoke of the beam clamp failed in a brittle mode at under less than 10% of the rated design capacity of 14,500 lb. The beam clamp had been in service for approximately 16 months. Bechtel Jacobs approached Argonne National Laboratory to assist in identifying the root cause of the failure of the beam clamp. The objectives of this study were to (1) review the prior reports and documents on the subject, (2) understand the possible failure mechanism(s) that resulted in the failed beam clamp components, (3) recommend approaches to mitigate the failure mechanism(s), and (4) evaluate the modified beam clamp assemblies. …
Date: October 11, 2010
Creator: Singh, D.; Pappacena, K.; Gaviria, J.; Burtsteva, T. & Division, Nuclear Engineering
System: The UNT Digital Library
Lake Granbury and Lake Whitney Assessment Initiative Final Scientific/Technical Report Summary (open access)

Lake Granbury and Lake Whitney Assessment Initiative Final Scientific/Technical Report Summary

A team of Texas AgriLife Research, Baylor University and University of Texas at Arlington researchers studied the biology and ecology of Prymnesium parvum (golden algae) in Texas lakes using a three-fold approach that involved system-wide monitoring, experimentation at the microcosm and mesocosm scales, and mathematical modeling. The following are conclusions, to date, regarding this organism’s ecology and potential strategies for mitigation of blooms by this organism. In-lake monitoring revealed that golden algae are present throughout the year, even in lakes where blooms do not occur. Compilation of our field monitoring data with data collected by Texas Parks and Wildlife and Brazos River Authority (a period spanning a decade) revealed that inflow and salinity variables affect bloom formations. Thresholds for algae populations vary per lake, likely due to adaptations to local conditions, and also to variations in lake-basin morphometry, especially the presence of coves that may serve as hydraulic storage zones for P. parvum populations. More specifically, our in-lake monitoring showed that the highly toxic bloom that occurred in Lake Granbury in the winter of 2006/2007 was eliminated by increased river inflow events. The bloom was flushed from the system. The lower salinities that resulted contributed to golden algae not blooming …
Date: October 11, 2010
Creator: Harris, B.L.; Roelke, Daniel; Brooks, Bryan & Grover, James
System: The UNT Digital Library
Studying Gaugino mass in Semi-Direct Gauge Mediation (open access)

Studying Gaugino mass in Semi-Direct Gauge Mediation

We study gaugino mass generation in the context of semi-direct gauge mediation models, where the messengers are charged under both the hidden sector and the standard model gauge groups while they do not play important roles in dynamical supersymmetry breaking. We clarify the cancellation of the leading contributions of the supersymmetry breaking effects to the gaugino mass in this class of models in terms of the macroscopic effective theory of the hidden sector dynamics. We also consider how to retrofit the model so that we obtain the non-vanishing leading contribution to the gaugino mass.
Date: June 11, 2010
Creator: Ibe, M.; Izawa, K. -I. & Nakai, Y.
System: The UNT Digital Library
IMPACT OF REDUCING THE 100 C LIQUIDUS TEMPERATURE OFFSET ON WASTE LOADING TARGETS (open access)

IMPACT OF REDUCING THE 100 C LIQUIDUS TEMPERATURE OFFSET ON WASTE LOADING TARGETS

The objective of this report is to assess the potential impact of reducing conservatism in the implementation of the current liquidus temperature (TL) model in the Product Composition Control System (PCCS) on the ability to target higher waste loadings (WLs) for future sludge batches. No changes to the TL model or the associated uncertainties (model or measurement) are proposed, rather only changes in the magnitude of the offset used between the nominal melt pool temperature (1150 C) and the Property Acceptance Region (PAR) value (1050 C). This strategy is consistent with that outlined and initially assessed by Brown et al. (2001). In that report, the authors stated even a fairly conservative change in this safety factor could have a significant impact on waste loading. The results of this study clearly indicate that the implementation of an 1100 C TL PAR criterion (which translates into a reduction in the TL offset from 100 C to 50 C) can have significantly positive impacts on the ability to gain access to WLs exceeding 45%. This is especially true for those frit and sludge systems that are TL limited using the current 1050 C TL criterion, and are not limited by a second constraint …
Date: November 11, 2010
Creator: Peeler, D. & Edwards, T.
System: The UNT Digital Library
Life-Cycle Analysis Results of Geothermal Systems in Comparison to Other Power Systems. (open access)

Life-Cycle Analysis Results of Geothermal Systems in Comparison to Other Power Systems.

A life-cycle energy and greenhouse gas emissions analysis has been conducted with Argonne National Laboratory's expanded Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model for geothermal power-generating technologies, including enhanced geothermal, hydrothermal flash, and hydrothermal binary technologies. As a basis of comparison, a similar analysis has been conducted for other power-generating systems, including coal, natural gas combined cycle, nuclear, hydroelectric, wind, photovoltaic, and biomass by expanding the GREET model to include power plant construction for these latter systems with literature data. In this way, the GREET model has been expanded to include plant construction, as well as the usual fuel production and consumption stages of power plant life cycles. For the plant construction phase, on a per-megawatt (MW) output basis, conventional power plants in general are found to require less steel and concrete than renewable power systems. With the exception of the concrete requirements for gravity dam hydroelectric, enhanced geothermal and hydrothermal binary used more of these materials per MW than other renewable power-generation systems. Energy and greenhouse gas (GHG) ratios for the infrastructure and other life-cycle stages have also been developed in this study per kilowatt-hour (kWh) of electricity output by taking into account both plant …
Date: October 11, 2010
Creator: Sullivan, J. L.; Clark, C. E.; Han, J.; Wang, M. & Systems, Energy
System: The UNT Digital Library
A Simple Apparatus for the Injection of Lithium Aerosol into the Scrape-Off Layer of Fusion Research Devices (open access)

A Simple Apparatus for the Injection of Lithium Aerosol into the Scrape-Off Layer of Fusion Research Devices

A simple device has been developed to deposit elemental lithium onto plasma facing components in the National Spherical Torus Experiment. Deposition is accomplished by dropping lithium powder into the plasma column. Once introduced, lithium particles quickly become entrained in scrape-off layer flow as an evaporating aerosol. Particles are delivered through a small central aperture in a computer-controlled resonating piezoelectric disk on which the powder is supported. The device has been used to deposit lithium both during discharges as well as prior to plasma breakdown. Clear improvements to plasma performance have been demonstrated. The use of this apparatus provides flexibility in the amount and timing of lithium deposition and, therefore, may benefit future fusion research devices.
Date: October 11, 2010
Creator: D. K. Mansfield, A.L Roquemore, H. Schneider, J. Timberlake, H. Kugel, M.G. Bell and the NSTX Research Team
System: The UNT Digital Library
National Emission Standards for Hazardous Air Pollutants - Radionuclide Emissions Calendar Year 2009 (open access)

National Emission Standards for Hazardous Air Pollutants - Radionuclide Emissions Calendar Year 2009

The U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office operates the Nevada Test Site (NTS) and North Las Vegas Facility (NLVF). From 1951 through 1992, the NTS was the continental testing location for U.S. nuclear weapons. The release of radionuclides from NTS activities has been monitored since the initiation of atmospheric testing. Limitation to underground detonations after 1962 greatly reduced radiation exposure to the public surrounding the NTS. After nuclear testing ended in 1992, NTS radiation monitoring focused on detecting airborne radionuclides from historically contaminated soils. These radionuclides are derived from re-suspension of soil (primarily by wind) and emission of tritium-contaminated soil moisture through evapotranspiration. Low amounts of tritium were also emitted to air at the NLVF, an NTS support complex in North Las Vegas. To protect the public from harmful levels of man-made radiation, the Clean Air Act, National Emission Standards for Hazardous Air Pollutants (NESHAP) (Title 40 Code of Federal Regulations [CFR] Part 61 Subpart H) limits the release of radioactivity from a U.S. Department of Energy facility to 10 millirem per year (mrem/yr) effective dose equivalent to any member of the public. This limit does not include radiation not related to NTS activities. Unrelated …
Date: June 11, 2010
Creator: Monitoring, NSTec Ecological and Environmental
System: The UNT Digital Library
YALINA-booster Subcritical Assembly Pulsed-Neutron Experiments : Data Processing and Spatial Corrections. (open access)

YALINA-booster Subcritical Assembly Pulsed-Neutron Experiments : Data Processing and Spatial Corrections.

The YALINA-Booster experiments and analyses are part of the collaboration between Argonne National Laboratory of USA and the Joint Institute for Power & Nuclear Research - SOSNY of Belarus for studying the physics of accelerator driven systems for nuclear energy applications using low enriched uranium. The YALINA-Booster subcritical assembly is utilized for studying the kinetics of accelerator driven systems with its highly intensive D-T or D-D pulsed neutron source. In particular, the pulsed neutron methods are used to determine the reactivity of the subcritical system. This report examines the pulsed-neutron experiments performed in the YALINA-Booster facility with different configurations for the subcritical assembly. The 1141 configuration with 90% U-235 fuel and the 1185 configuration with 36% or 21% U-235 fuel are examined. The Sjoestrand area-ratio method is utilized to determine the reactivities of the different configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from the experimental data are shown to be dependent on the detector locations inside the subcritical assembly and the types of detector used for the measurements. In this report, Bell's spatial correction factors are calculated based on a Monte Carlo model to …
Date: October 11, 2010
Creator: Cao, Y.; Gohar, Y. & Division, Nuclear Engineering
System: The UNT Digital Library
YALINA-booster Subcritical Assembly Pulsed-Neutron E Xperiments: Detector Dead Time and Apatial Corrections. (open access)

YALINA-booster Subcritical Assembly Pulsed-Neutron E Xperiments: Detector Dead Time and Apatial Corrections.

In almost every detector counting system, a minimal dead time is required to record two successive events as two separated pulses. Due to the random nature of neutron interactions in the subcritical assembly, there is always some probability that a true neutron event will not be recorded because it occurs too close to the preceding event. These losses may become rather severe for counting systems with high counting rates, and should be corrected before any utilization of the experimental data. This report examines the dead time effects for the pulsed neutron experiments of the YALINA-Booster subcritical assembly. The nonparalyzable model is utilized to correct the experimental data due to dead time. Overall, the reactivity values are increased by 0.19$ and 0.32$ after the spatial corrections for the YALINA-Booster 36% and 21% configurations respectively. The differences of the reactivities obtained with He-3 long or short detectors at the same detector channel diminish after the dead time corrections of the experimental data for the 36% YALINA-Booster configuration. In addition, better agreements between reactivities obtained from different experimental data sets are also observed after the dead time corrections for the 21% YALINA-Booster configuration.
Date: October 11, 2010
Creator: Cao, Y.; Gohar, Y. & Division, Nuclear Engineering
System: The UNT Digital Library
The Influence of Cloud Microphysics and Radiation on the Response of Water Vapor and Clouds to Climate Change (open access)

The Influence of Cloud Microphysics and Radiation on the Response of Water Vapor and Clouds to Climate Change

Uncertainties in representing the atmospheric water cycle are major obstacles to the accurate prediction of future climate. This project focused on addressing some of these uncertainties by implementing new physics for convection and radiation into the NCAR Community Atmosphere Model (CAM). To better understand and eventually better represent these processes in this major national climate model, we modified CAM3.5 to use the convection and cloud schemes developed by the Massachusetts Institute of Technology (MIT) and the RRTMG rapid radiation code for global climate models developed by Atmospheric and Environmental Research, Inc. (AER). The impact of the new physics on the CAM3.5 simulation of convection on diurnal and intra-seasonal scales, on intra-seasonal oscillations and on the distribution of water vapor has been investigated. In addition, the MIT and AER physics packages have been incorporated and tested in combination within the Weather Research and Forecasting (WRF) regional forecast model for the purpose of evaluating and improving convective and radiative processes on time scales appropriate to weather simulations. It has been found that the application of the AER radiation and MIT convection produces significant improvements in the modeled diurnal cycle of convection, especially over land, in the NCAR climate model. However, both the …
Date: November 11, 2010
Creator: Emanuel, Kerry & Iacono, Michael J.
System: The UNT Digital Library
100-N Area Strontium-90 Treatability Demonstration Project: Phytoextraction Along the 100-N Columbia River Riparian Zone – Field Treatability Study (open access)

100-N Area Strontium-90 Treatability Demonstration Project: Phytoextraction Along the 100-N Columbia River Riparian Zone – Field Treatability Study

Strontium-90 (90Sr) is present both in the aquifer near the river and in the vadose and riparian zones of the river’s shore at 100-NR-2. Phytoextraction of 90Sr is being considered as a potential remediation system along the riparian zone of the Columbia River. Phytoextraction would employ coyote willow (Salix exigua). Past studies have shown that willow roots share uptake mechanisms for Sr with Ca, a plant macronutrient as well as no discrimination between Sr and 90Sr. Willow 90Sr concentration ratios [CR’s; (pCi 90Sr/g dry wt. of new growth tissue)/(pCi 90Sr/g soil porewater)] were consistently greater than 65 with three-quarters of the assimilated label partitioned into the above ground shoot. Insect herbivore experiments also demonstrated no significant potential for bioaccumulation or food chain transfer from their natural activities. The objectives of this field study were three-fold: (1) to demonstrate that a viable, “managed” plot of coyote willows can be established on the shoreline of the Columbia River that would survive the same microenvironment to be encountered at the 100-NR-2 shoreline; (2) to show through engineered barriers that large and small animal herbivores can be prevented from feeding on these plants; and (3) to show that once established, the plants will provide …
Date: January 11, 2010
Creator: Fellows, Robert J.; Fruchter, Jonathan S.; Driver, Crystal J. & Ainsworth, Calvin C.
System: The UNT Digital Library
Colling Wipe Samples for VX Analysis (open access)

Colling Wipe Samples for VX Analysis

This standard operating procedure (SOP) provides uniform procedures for the collection of wipe samples of VX residues from surfaces. Personnel may use this procedure to collect and handle wipe samples in the field. Various surfaces, including building materials (wood, metal, tile, vinyl, etc.) and equipment, may be sampled based on this procedure. The purpose of such sampling is to determine whether or not the relevant surfaces are contaminated, to determine the extent of their contamination, to evaluate the effectiveness of decontamination procedures, and to determine the amount of contaminant that might present as a contact hazard.
Date: February 11, 2010
Creator: Koester, C & Hoppes, W G
System: The UNT Digital Library
Hi-Q Rotor - Low Wind Speed Technology (open access)

Hi-Q Rotor - Low Wind Speed Technology

The project objective was to optimize the performance of the Hi-Q Rotor. Early research funded by the California Energy Commission indicated the design might be advantageous over state-of-the-art turbines for collecting wind energy in low wind conditions. The Hi-Q Rotor is a new kind of rotor targeted for harvesting wind in Class 2, 3, and 4 sites, and has application in areas that are closer to cities, or 'load centers.' An advantage of the Hi-Q Rotor is that the rotor has non-conventional blade tips, producing less turbulence, and is quieter than standard wind turbine blades which is critical to the low-wind populated urban sites. Unlike state-of-the-art propeller type blades, the Hi-Q Rotor has six blades connected by end caps. In this phase of the research funded by DOE's Inventions and Innovation Program, the goal was to improve the current design by building a series of theoretical and numeric models, and composite prototypes to determine a best of class device. Development of the rotor was performed by aeronautical engineering and design firm, DARcorporation. From this investigation, an optimized design was determined and an 8-foot diameter, full-scale rotor was built and mounted using a Bergey LX-1 generator and furling system which were …
Date: January 11, 2010
Creator: Mills, Todd E. & Tatum, Judy
System: The UNT Digital Library
Impedance Scaling for Small-angle Tapers and Collimators (open access)

Impedance Scaling for Small-angle Tapers and Collimators

In this note I will prove that the impedance calculated for a small-angle collimator or taper, of arbitrary 3D profile, has a scaling property that can greatly simplify numerical calculations. This proof is based on the parabolic equation approach to solving Maxwell's equation developed in Refs. [1, 2]. We start from the parabolic equation formulated in [3]. As discussed in [1], in general case this equation is valid for frequencies {omega} >> c/a where a is a characteristic dimension of the obstacle. However, for small-angle tapers and collimators, the region of validity of this equation extends toward smaller frequencies and includes {omega} {approx} c/a.
Date: February 11, 2010
Creator: Stupakov, G.
System: The UNT Digital Library
DOE-EPSCOR SPONSORED PROJECT FINAL REPORT (open access)

DOE-EPSCOR SPONSORED PROJECT FINAL REPORT

Concern over the quality of environmental management and restoration has motivated the model development for predicting water and solute transport in the vadose zone. Soil hydraulic properties are required inputs to subsurface models of water flow and contaminant transport in the vadose zone. Computer models are now routinely used in research and management to predict the movement of water and solutes into and through the vadose zone of soils. Such models can be used successfully only if reliable estimates of the soil hydraulic parameters are available. The hydraulic parameters considered in this project consist of the saturated hydraulic conductivity and four parameters of the water retention curves. To quantify hydraulic parameters for heterogeneous soils is both difficult and time consuming. The overall objective of this project was to better quantify soil hydraulic parameters which are critical in predicting water flows and contaminant transport in the vadose zone through a comprehensive and quantitative study to predict heterogeneous soil hydraulic properties and the associated uncertainties. Systematic and quantitative consideration of the parametric heterogeneity and uncertainty can properly address and further reduce predictive uncertainty for contamination characterization and environmental restoration at DOE-managed sites. We conducted a comprehensive study to assess soil hydraulic parameter …
Date: March 11, 2010
Creator: Zhu, Jianting
System: The UNT Digital Library
Understanding the mechanism of nanotube synthesis for controlled production of specific (n,m) structures (open access)

Understanding the mechanism of nanotube synthesis for controlled production of specific (n,m) structures

This report shows the extensive research on the mechanism responsible for the formation of single walled carbon nanotubes in order to get control over their structural parameters (diameter and chirality). Catalyst formulations, pre-treatment conditions, and reaction conditions are described in detail as well as mechanisms to produce nanotubes structures of specific arrays (vertical forest, nanotube pillars). Applications of SWNT in different fields are also described in this report. In relation to this project five students have graduated (3 PhD and 2 MS) and 35 papers have been published.
Date: February 11, 2010
Creator: Resasco, Daniel E.
System: The UNT Digital Library
Integrating the Molecular Machines of Mercury Detoxification into Host Cell Biology (open access)

Integrating the Molecular Machines of Mercury Detoxification into Host Cell Biology

Integrating the Molecular Machines of Mercury Detoxification into Host Cell Biology The bacterial mercury resistance (mer) operon, one of the most evolutionarily successful genetic loci in any defined organism, detoxifies organic and inorganic mercury compounds. Several major biotic processes in the global Hg(II) cycle are carried out by bacteria with this highly mobile detoxification locus that occurs in Gram negative and high and low GC Gram positive bacteria. The functions of many individual mer operon components are well described, so we aim to dissect the higher order interactions of the enzymes, transporters, and regulators of this paradigm metal metabolizing system with each other and with the larger metabolism of the host cell. Understanding how this ubiquitous detoxification system fits into the biology and ecology of its bacterial host is essential to guide interventions that support and enhance Hg remediation. Specifically, we will test the hypotheses that: (a) the organomercurial lyase, MerB, and the mercuric reductase, MerA, act synergistically together and with the membrane-bound Hg(II) transporters, MerT and MerC, to detoxify mercurials; (b) the interaction of the metalloregulator MerR with RNA polymerase (RNAP) and with its DNA binding site, MerO, modulates its metal response, and interaction with its antagonist, MerD, prevents …
Date: March 11, 2010
Creator: Summers, Anne O
System: The UNT Digital Library
Harnessing the Chemistry of CO2 (open access)

Harnessing the Chemistry of CO2

Our research program is broadly focused on activating CO{sub 2} through the use of organic and organometallic based catalysts. Some of our methods have centered on annulation reactions of unsaturated hydrocarbons (and carbonyl substrates) to provide a diverse array of carbocycles and heterocycles. We use a combination of catalyst discovery and optimization in conjunction with classical physical organic chemistry to elucidate the key mechanistic features of the cycloaddition reactions such that the next big advances in catalyst development can be made. Key to all of our cycloaddition reactions is the use of a sterically hindered, electron donating N heterocyclic carbene (NHC) ligand, namely IPr (or SIPr), in conjunction with a low valent nickel pre-catalyst. The efficacy of this ligand is two-fold: (1) the high {delta}-donating ability of the NHC increases the nucleophilicity of the metal center which thereby facilitates interaction with the electrophilic carbonyl and (2) the steric hindrance prevents an otherwise competitive side reaction involving only the alkyne substrate. Such a system has allowed for the facile cycloaddition to prepare highly functionalized pyrones, pyridones, pyrans, as well as novel carbocycles. Importantly, all reactions proceed under extremely mild conditions (room temperature, atmospheric pressures, and short reaction times), require only catalytic …
Date: May 11, 2010
Creator: Louie, Janis
System: The UNT Digital Library