Timescales and settings for alteration of chondritic meteorites (open access)

Timescales and settings for alteration of chondritic meteorites

Most groups of chondritic meteorites experienced diverse styles of secondary alteration to various degrees that resulted in formation of hydrous and anhydrous minerals (e.g., phyllosilicates, magnetite, carbonates, ferrous olivine, hedenbergite, wollastonite, grossular, andradite, nepheline, sodalite, Fe,Ni-carbides, pentlandite, pyrrhotite, Ni-rich metal). Mineralogical, petrographic, and isotopic observations suggest that the alteration occurred in the presence of aqueous solutions under variable conditions (temperature, water/rock ratio, redox conditions, and fluid compositions) in an asteroidal setting, and, in many cases, was multistage. Although some alteration predated agglomeration of the final chondrite asteroidal bodies (i.e. was pre-accretionary), it seems highly unlikely that the alteration occurred in the solar nebula, nor in planetesimals of earlier generations. Short-lived isotope chronologies ({sup 26}Al-{sup 26}Mg, {sup 53}Mn-{sup 53}Cr, {sup 129}I-{sup 129}Xe) of the secondary minerals indicate that the alteration started within 1-2 Ma after formation of the Ca,Al-rich inclusions and lasted up to 15 Ma. These observations suggest that chondrite parent bodies must have accreted within the first 1-2 Ma after collapse of the protosolar molecular cloud and provide strong evidence for an early onset of aqueous activity on these bodies.
Date: November 16, 2005
Creator: Krot, A. N.; Hutcheon, I. D.; Brearley, A. J.; Pravdivtseva, O. V.; Petaev, M. I. & Hohenberg, C. M.
System: The UNT Digital Library
Reconstructing Past Ocean Salinity ((delta)18Owater) (open access)

Reconstructing Past Ocean Salinity ((delta)18Owater)

Temperature and salinity are two of the key properties of ocean water masses. The distribution of these two independent but related characteristics reflects the interplay of incoming solar radiation (insolation) and the uneven distribution of heat loss and gain by the ocean, with that of precipitation, evaporation, and the freezing and melting of ice. Temperature and salinity to a large extent, determine the density of a parcel of water. Small differences in temperature and salinity can increase or decrease the density of a water parcel, which can lead to convection. Once removed from the surface of the ocean where 'local' changes in temperature and salinity can occur, the water parcel retains its distinct relationship between (potential) temperature and salinity. We can take advantage of this 'conservative' behavior where changes only occur as a result of mixing processes, to track the movement of water in the deep ocean (Figure 1). The distribution of density in the ocean is directly related to horizontal pressure gradients and thus (geostrophic) ocean currents. During the Quaternary when we have had systematic growth and decay of large land based ice sheets, salinity has had to change. A quick scaling argument following that of Broecker and Peng …
Date: November 23, 2005
Creator: Guilderson, T. P. & Pak, D. K.
System: The UNT Digital Library
Buildings Sector Analysis (open access)

Buildings Sector Analysis

A joint NREL, ORNL, and PNNL team conducted market analysis to help inform DOE/EERE's Weatherization and Intergovernmental Program planning and management decisions. This chapter presents the results of the market analysis for the Buildings sector.
Date: August 1, 2005
Creator: Hostick, Donna J.; Nicholls, Andrew K.; McDonald, Sean C. & Hollomon, Jonathan B.
System: The UNT Digital Library
From Sequential Extraction to Transport Modeling: Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants (open access)

From Sequential Extraction to Transport Modeling: Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants

To quantify metal natural attenuation processes in terms of environmental availability, sequential extraction experiments were carried out on subsurface soil samples impacted by a low pH, high sulfate, metals (Be, Ni, U, As) plume associated with the long-term operation of a coal plant at the Savannah River Site in South Carolina. Despite significant heterogeneity resulting both from natural and anthropogenic factors, sequential extraction results demonstrate that pH is a controlling factor in the prediction of the distribution of metal contaminants within the solid phases in soils at the site as well as the contaminant partitioning between the soil and the soil solution. Results for beryllium, the most mobile metal evaluated, exhibit increasing attenuation along the plume flow path which corresponds to an increasing plume pH. These laboratory- and field-scale studies provide mechanistic information regarding partitioning of metals to soils at the site (one of the major attenuation mechanisms for the metals at the field site). Subsequently, these data have been used in the definition of the contaminant source terms and contaminant transport factors in risk modeling for the site.
Date: August 18, 2005
Creator: Crapse, Kimberly P.; Serkiz, Steven M.; Pishko, Adrian L.; Kaplan, Daniel L.; Lee, Cindy M. & Schank, Anja
System: The UNT Digital Library
Development and Application of Compatible Discretizations of Maxwell's Equations (open access)

Development and Application of Compatible Discretizations of Maxwell's Equations

We present the development and application of compatible finite element discretizations of electromagnetics problems derived from the time dependent, full wave Maxwell equations. We review the H(curl)-conforming finite element method, using the concepts and notations of differential forms as a theoretical framework. We chose this approach because it can handle complex geometries, it is free of spurious modes, it is numerically stable without the need for filtering or artificial diffusion, it correctly models the discontinuity of fields across material boundaries, and it can be very high order. Higher-order H(curl) and H(div) conforming basis functions are not unique and we have designed an extensible C++ framework that supports a variety of specific instantiations of these such as standard interpolatory bases, spectral bases, hierarchical bases, and semi-orthogonal bases. Virtually any electromagnetics problem that can be cast in the language of differential forms can be solved using our framework. For time dependent problems a method-of-lines scheme is used where the Galerkin method reduces the PDE to a semi-discrete system of ODE's, which are then integrated in time using finite difference methods. For time integration of wave equations we employ the unconditionally stable implicit Newmark-Beta method, as well as the high order energy conserving …
Date: May 27, 2005
Creator: White, D.; Koning, J. & Rieben, R.
System: The UNT Digital Library
Volume visualization of multiple alignment of large genomicDNA (open access)

Volume visualization of multiple alignment of large genomicDNA

Genomes of hundreds of species have been sequenced to date, and many more are being sequenced. As more and more sequence data sets become available, and as the challenge of comparing these massive ''billion basepair DNA sequences'' becomes substantial, so does the need for more powerful tools supporting the exploration of these data sets. Similarity score data used to compare aligned DNA sequences is inherently one-dimensional. One-dimensional (1D) representations of these data sets do not effectively utilize screen real estate. As a result, tools using 1D representations are incapable of providing informatory overview for extremely large data sets. We present a technique to arrange 1D data in 3D space to allow us to apply state-of-the-art interactive volume visualization techniques for data exploration. We demonstrate our technique using multi-millions-basepair-long aligned DNA sequence data and compare it with traditional 1D line plots. The results show that our technique is superior in providing an overview of entire data sets. Our technique, coupled with 1D line plots, results in effective multi-resolution visualization of very large aligned sequence data sets.
Date: July 25, 2005
Creator: Shah, Nameeta; Dillard, Scott E.; Weber, Gunther H. & Hamann, Bernd
System: The UNT Digital Library
USE OF AN EQUILIBRIUM MODEL TO FORECAST DISSOLUTION EFFECTIVENESS, SAFETY IMPACTS, AND DOWNSTREAM PROCESSABILITY FROM OXALIC ACID AIDED SLUDGE REMOVAL IN SAVANNAH RIVER SITE HIGH LEVEL WASTE TANKS 1-15 (open access)

USE OF AN EQUILIBRIUM MODEL TO FORECAST DISSOLUTION EFFECTIVENESS, SAFETY IMPACTS, AND DOWNSTREAM PROCESSABILITY FROM OXALIC ACID AIDED SLUDGE REMOVAL IN SAVANNAH RIVER SITE HIGH LEVEL WASTE TANKS 1-15

This thesis details a graduate research effort written to fulfill the Magister of Technologiae in Chemical Engineering requirements at the University of South Africa. The research evaluates the ability of equilibrium based software to forecast dissolution, evaluate safety impacts, and determine downstream processability changes associated with using oxalic acid solutions to dissolve sludge heels in Savannah River Site High Level Waste (HLW) Tanks 1-15. First, a dissolution model is constructed and validated. Coupled with a model, a material balance determines the fate of hypothetical worst-case sludge in the treatment and neutralization tanks during each chemical adjustment. Although sludge is dissolved, after neutralization more is created within HLW. An energy balance determines overpressurization and overheating to be unlikely. Corrosion induced hydrogen may overwhelm the purge ventilation. Limiting the heel volume treated/acid added and processing the solids through vitrification is preferred and should not significantly increase the number of glass canisters.
Date: October 31, 2005
Creator: Ketusky, Edward
System: The UNT Digital Library
Susceptibility to Exposure to Heterocyclic Amines from Cooked Food: Role of UDP-glucuronosyltransferases (open access)

Susceptibility to Exposure to Heterocyclic Amines from Cooked Food: Role of UDP-glucuronosyltransferases

A number of carcinogenic heterocyclic amines (PhIP, MeIQx, and DiMeIQx) are produced from the condensation of creatinine, hexoses and amino acids during the cooking of meat (1). There are many variables that impact the production and subsequent ingestion of these compounds in our diet. Temperature, type of meat product, cooking method, doneness, and other factors affect the quantity of these carcinogens consumed by humans. Estimates of ingestion of these carcinogens are 1-20 ng/kg body weight per day (2). Human case control studies that correlate meat consumption from well-done cooking practices with cancer incidence indicate excess tumors for breast, colon, stomach, esophagus, and possibly prostate (3-5).
Date: August 22, 2005
Creator: Malfatti, M. A. & Felton, J. S.
System: The UNT Digital Library
Aerosol, Clouds, and Climate Change (open access)

Aerosol, Clouds, and Climate Change

Earth's climate is thought to be quite sensitive to changes in radiative fluxes that are quite small in absolute magnitude, a few watts per square meter, and in relation to these fluxes in the natural climate. Atmospheric aerosol particles exert influence on climate directly, by scattering and absorbing radiation, and indirectly by modifying the microphysical properties of clouds and in turn their radiative effects and hydrology. The forcing of climate change by these indirect effects is thought to be quite substantial relative to forcing by incremental concentrations of greenhouse gases, but highly uncertain. Quantification of aerosol indirect forcing by satellite- or ground-based remote sensing has proved quite difficult in view of inherent large variation in the pertinent observables such as cloud optical depth, which is controlled mainly by liquid water path and only secondarily by aerosols. Limited work has shown instances of large magnitude of aerosol indirect forcing, with local instantaneous forcing upwards of 50 W m{sup 66}-2. Ultimately it will be necessary to represent aerosol indirect effects in climate models to accurately identify the anthropogenic forcing at present and over secular time and to assess the influence of this forcing in the context of other forcings of climate change. …
Date: September 1, 2005
Creator: Schwartz, S. E.
System: The UNT Digital Library
Influence Of Coal Combustion Flue Gas Desulfurization Waste On Element Uptake By Maize (Zea Mays L.) (open access)

Influence Of Coal Combustion Flue Gas Desulfurization Waste On Element Uptake By Maize (Zea Mays L.)

A greenhouse study was conducted to determine the effect of coal combustion flue gas desulfurization (FGD) waste from a coal combustion electric power facility on element uptake by maize (Zea mays L.). Unweathered FGD was applied to an Orangeburg Series (Typic Paleudult) soil with an initial soil pH salt of 4.90. The FGD was added at 0, 1, 2, 4, 6, 8, and 10 per cent by weight. The test plant, maize, was harvested after 6 weeks of growth. Within 56 days of the FGD application, all rates of FGD significantly increased pH in the soil and the soil leachate above 6.0. The elemental concentration of the maize tissues indicated a characteristic elevation of B, Se, Mo, and As. However, no visual symptoms of toxicity of B or other elements in plants were observed. Increasing level of FGD caused a steady decline in dry weight, with the highest treatment producing plants which had approximately half the biomass of the control plants. Due to elevated concentrations of B and other elements and due to adverse yield effects measured on plants, unweathered FGD would not be a suitable amendment for 6-week old maize on this soil.
Date: January 10, 2005
Creator: Knox, Anna S.; Knox, John D.; Adriano, Domy C. & Sajwan, Kenneth S.
System: The UNT Digital Library
Norcal Prototype LNG Truck Fleet: Final Data Report (open access)

Norcal Prototype LNG Truck Fleet: Final Data Report

U.S. DOE and National Renewable Energy Laboratory evaluated Norcal Waste Systems liquefied natural gas (LNG) waste transfer trucks. Trucks had prototype Cummins Westport ISXG engines. Report gives final data.
Date: February 1, 2005
Creator: Chandler, K. & Proc, K.
System: The UNT Digital Library
Assessing the Potential for Renewable Energy on National Forest System Lands (open access)

Assessing the Potential for Renewable Energy on National Forest System Lands

This technical report and CD for the U.S. Department of Agriculture, Forest Service (USFS), evaluates the potential for renewable energy resource development on National Forest System (NFS) lands. USFS can use the report findings to consider potential for development of solar and wind energy resources on NFS lands, in land management decisions. The Geographical Information System (GIS) based analysis resulted in the following findings: (1) Ninety-nine National Forest Units have high potential for power production from one or more of these solar and wind energy sources; and (2) Twenty National Forest Units in nine states have high potential for power production from two or more of these solar and wind energy sources.
Date: January 1, 2005
Creator: unknown
System: The UNT Digital Library
International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen: Book of Abstracts (open access)

International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen: Book of Abstracts

The International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen provides an opportunity to learn about current significant research on solar concentrators for generating electricity or hydrogen. The conference will emphasize in-depth technical discussions of recent achievements in technologies that convert concentrated solar radiation to electricity or hydrogen, with primary emphasis on photovoltaic (PV) technologies. Very high-efficiency solar cells--above 37%--were recently developed, and are now widely used for powering satellites. This development demands that we take a fresh look at the potential of solar concentrators for generating low-cost electricity or hydrogen. Solar electric concentrators could dramatically overtake other PV technologies in the electric utility marketplace because of the low capital cost of concentrator manufacturing facilities and the larger module size of concentrators. Concentrating solar energy also has advantages for th e solar generation of hydrogen. Around the world, researchers and engineers are developing solar concentrator technologies for entry into the electricity generation market and several have explored the use of concentrators for hydrogen production. The last conference on the subject of solar electric concentrators was held in November of 2003 and proved to be an important opportunity for researchers and developers to share new and crucial information …
Date: May 1, 2005
Creator: McConnell, R.; Symko-Davies, M. & Hayden, H.
System: The UNT Digital Library
Development of U.S. Regulations for the Transportation of Radioactive Materials - A Look Back Over the Past 40 Years (open access)

Development of U.S. Regulations for the Transportation of Radioactive Materials - A Look Back Over the Past 40 Years

The discussion in this Chapter is a relatively straightforward, chronological description of the development of U.S. transportation regulations for radioactive materials over the past 40 years. Although primarily based on the development of U.S. regulations for the shipment of what is now known as Type B quantities of radioactive materials, the information presented details the interactions between a number of U.S. governmental agencies, commissions, and departments, and the International Atomic Energy Agency (IAEA). For the most part, the information that follows was taken directly from the Federal Register, between 1965 and 2004, which, within the boundaries of the U.S., is considered law, or at least policy at the federal level. Starting in 1978, however, the information presented also takes a look at a series of so-called Guidance Documents, including Regulatory Guides (Reg. Guides), NUREGs, and NUREG/CRs. Developed originally by the U.S. Atomic Energy Agency (AEC), and later adapted by the U.S. Nuclear Regulatory Commission (NRC), the NUREGs and NUREG/CRs cited in this Chapter clearly specify a preferred methodology that can be used to meet the regulatory requirements of Title 10 of the Code of Federal Regulations, Part 71 (10 CFR Part 71, or, more simply, 10 CFR 71). As is …
Date: August 29, 2005
Creator: Hafner, R. S.
System: The UNT Digital Library
Applications of Morphochronology to the Active Tectonics of Tibet (open access)

Applications of Morphochronology to the Active Tectonics of Tibet

The Himalayas and the Tibetan Plateau were formed as a result of the collision of India and Asia, and provide an excellent opportunity to study the mechanical response of the continental lithosphere to tectonic stress. Geophysicists are divided in their views on the nature of this response advocating either (1) homogeneously distributed deformation with the lithosphere deforming as a fluid continuum or (2) deformation is highly localized with the lithosphere that deforms as a system of blocks. The resolution of this issue has broad implications for understanding the tectonic response of continental lithosphere in general. Homogeneous deformation is supported by relatively low decadal, geodetic slip-rate estimates for the Altyn Tagh and Karakorum Faults. Localized deformation is supported by high millennial, geomorphic slip-rates constrained by both cosmogenic and radiocarbon dating on these faults. Based upon the agreement of rates determined by radiocarbon and cosmogenic dating, the overall linearity of offset versus age correlations, and on the plateau-wide correlation of landscape evolution and climate history, the disparity between geomorphic and geodetic slip-rate determinations is unlikely to be due to the effects of surface erosion on the cosmogenic age determinations. Similarly, based upon the consistency of slip-rates over various observation intervals, secular variations …
Date: January 28, 2005
Creator: Ryerson, F. J.; Tapponnier, P.; Finkel, R. C.; Meriaux, A.; der Woerd, J. V.; Lasserre, C. et al.
System: The UNT Digital Library
Constraints on the Origin of Chondrules and CAIs from Short-Lived and Long-Lived Radionuclides (open access)

Constraints on the Origin of Chondrules and CAIs from Short-Lived and Long-Lived Radionuclides

The high time resolution Pb-Pb ages and short-lived nuclide based relative ages for CAIs and chondrules are reviewed. The solar system started at 4567.2 {+-} 0.6Ma inferred from the high precision Pb-Pb ages of CAIs. Time scales of CAIs ({le}0.1Myr), chondrules (1-3Myr), and early asteroidal differentiation ({ge}3Myr) inferred from {sup 26}Al relative ages are comparable to the time scale estimated from astronomical observations of young star; proto star, classical T Tauri star and week-lined T Tauri star, respectively. Pb-Pb ages of chondrules also indicate chondrule formation occur within 1-3 Myr after CAIs. Mn-Cr isochron ages of chondrules are similar to or within 2 Myr after CAI formation. Chondrules from different classes of chondrites show the same range of {sup 26}Al ages in spite of their different oxygen isotopes, indicating that chondrule formed in the localized environment. The {sup 26}Al ages of chondrules in each chondrite class show a hint of correlation with their chemical compositions, which implies the process of elemental fractionation during chondrule formation events.
Date: October 24, 2005
Creator: Kita, N. T.; Huss, G. R.; Tachibana, S.; Amelin, Y.; Nyquist, L. E. & Hutcheon, I. D.
System: The UNT Digital Library
Biological Treatment of Petroleum in Radiologically Contaminated Soil (open access)

Biological Treatment of Petroleum in Radiologically Contaminated Soil

This chapter describes ex situ bioremediation of the petroleum portion of radiologically co-contaminated soils using microorganisms isolated from a waste site and innovative bioreactor technology. Microorganisms first isolated and screened in the laboratory for bioremediation of petroleum were eventually used to treat soils in a bioreactor. The bioreactor treated soils contaminated with over 20,000 mg/kg total petroleum hydrocarbon and reduced the levels to less than 100 mg/kg in 22 months. After treatment, the soils were permanently disposed as low-level radiological waste. The petroleum and radiologically contaminated soil (PRCS) bioreactor operated using bioventing to control the supply of oxygen (air) to the soil being treated. The system treated 3.67 tons of PCRS amended with weathered compost, ammonium nitrate, fertilizer, and water. In addition, a consortium of microbes (patent pending) isolated at the Savannah River National Laboratory from a petroleum-contaminated site was added to the PRCS system. During operation, degradation of petroleum waste was accounted for through monitoring of carbon dioxide levels in the system effluent. The project demonstrated that co-contaminated soils could be successfully treated through bioventing and bioaugmentation to remove petroleum contamination to levels below 100 mg/kg while protecting workers and the environment from radiological contamination.
Date: November 14, 2005
Creator: BERRY, CHRISTOPHER
System: The UNT Digital Library
Sequencing and comparing whole mitochondrial genomes ofanimals (open access)

Sequencing and comparing whole mitochondrial genomes ofanimals

Comparing complete animal mitochondrial genome sequences is becoming increasingly common for phylogenetic reconstruction and as a model for genome evolution. Not only are they much more informative than shorter sequences of individual genes for inferring evolutionary relatedness, but these data also provide sets of genome-level characters, such as the relative arrangements of genes, that can be especially powerful. We describe here the protocols commonly used for physically isolating mtDNA, for amplifying these by PCR or RCA, for cloning,sequencing, assembly, validation, and gene annotation, and for comparing both sequences and gene arrangements. On several topics, we offer general observations based on our experiences to date with determining and comparing complete mtDNA sequences.
Date: April 22, 2005
Creator: Boore, Jeffrey L.; Macey, J. Robert & Medina, Monica
System: The UNT Digital Library
Biodiesel--Clean, Green Diesel Fuel: Great Fleet Fuel Gaining Popularity Rapidly (open access)

Biodiesel--Clean, Green Diesel Fuel: Great Fleet Fuel Gaining Popularity Rapidly

A fact sheet that answers common questions about Biodiesel, including use, safety, and environmental questions.
Date: July 29, 2005
Creator: Tyson, K.S.
System: The UNT Digital Library