Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation (open access)

Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation

Recent results of thermodynamic studies on the complexation of actinides (UO{sub 2}{sup 2+}, NpO{sub 2}{sup +} and Pu{sup 4+}) with F{sup -}, SO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}/HPO{sub 4}{sup 2-} at elevated temperatures are reviewed. The data indicate that, for all systems except the 1:1 complexation of Np(V) with HPO{sub 4}{sup 2-}, the complexation of actinides is enhanced by the increase in temperature. The enhancement is primarily due to the increase in the entropy term (T{Delta}S) that exceeds the increase in the enthalpy ({Delta}H) as the temperature is increased. These data bridge the gaps in the chemical thermodynamic database for nuclear waste repository where the temperature could remain significantly higher than 25 C for a long time after the closure of the repository.
Date: December 21, 2009
Creator: Rao, Linfeng; Tian, Guoxin; Xia, Yuanxian; Friese, Judah I.; Zanonato, PierLuigi & Di Bernardo, Plinio
System: The UNT Digital Library
MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES (open access)

MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES

In this chapter we review the spectroscopic data for actinide molecules and the reaction dynamics for atomic and molecular actinides that have been examined in the gas phase or in inert cryogenic matrices. The motivation for this type of investigation is that physical properties and reactions can be studied in the absence of external perturbations (gas phase) or under minimally perturbing conditions (cryogenic matrices). This information can be compared directly with the results from high-level theoretical models. The interplay between experiment and theory is critically important for advancing our understanding of actinide chemistry. For example, elucidation of the role of the 5f electrons in bonding and reactivity can only be achieved through the application of experimentally verified theoretical models. Theoretical calculations for the actinides are challenging due the large numbers of electrons that must be treated explicitly and the presence of strong relativistic effects. This topic has been reviewed in depth in Chapter 17 of this series. One of the goals of the experimental work described in this chapter has been to provide benchmark data that can be used to evaluate both empirical and ab initio theoretical models. While gas-phase data are the most suitable for comparison with theoretical calculations, …
Date: February 1, 2009
Creator: Heaven, Michael C.; Gibson, John K. & Marcalo, Joaquim
System: The UNT Digital Library
Model Components of the Certification Framework for Geologic Carbon Sequestration Risk Assessment (open access)

Model Components of the Certification Framework for Geologic Carbon Sequestration Risk Assessment

We have developed a framework for assessing the leakage risk of geologic carbon sequestration sites. This framework, known as the Certification Framework (CF), emphasizes wells and faults as the primary potential leakage conduits. Vulnerable resources are grouped into compartments, and impacts due to leakage are quantified by the leakage flux or concentrations that could potentially occur in compartments under various scenarios. The CF utilizes several model components to simulate leakage scenarios. One model component is a catalog of results of reservoir simulations that can be queried to estimate plume travel distances and times, rather than requiring CF users to run new reservoir simulations for each case. Other model components developed for the CF and described here include fault characterization using fault-population statistics; fault connection probability using fuzzy rules; well-flow modeling with a drift-flux model implemented in TOUGH2; and atmospheric dense-gas dispersion using a mesoscale weather prediction code.
Date: June 1, 2009
Creator: Oldenburg, Curtis M.; Bryant, Steven L.; Nicot, Jean-Philippe; Kumar, Navanit; Zhang, Yingqi; Jordan, Preston et al.
System: The UNT Digital Library
MANHATTAN PROJECT B REACTOR HANFORD WASHINGTON [HANFORD'S HISTORIC B REACTOR (12-PAGE BOOKLET)] (open access)

MANHATTAN PROJECT B REACTOR HANFORD WASHINGTON [HANFORD'S HISTORIC B REACTOR (12-PAGE BOOKLET)]

The Hanford Site began as part of the United States Manhattan Project to research, test and build atomic weapons during World War II. The original 670-square mile Hanford Site, then known as the Hanford Engineer Works, was the last of three top-secret sites constructed in order to produce enriched uranium and plutonium for the world's first nuclear weapons. B Reactor, located about 45 miles northwest of Richland, Washington, is the world's first full-scale nuclear reactor. Not only was B Reactor a first-of-a-kind engineering structure, it was built and fully functional in just 11 months. Eventually, the shoreline of the Columbia River in southeastern Washington State held nine nuclear reactors at the height of Hanford's nuclear defense production during the Cold War era. The B Reactor was shut down in 1968. During the 1980's, the U.S. Department of Energy began removing B Reactor's support facilities. The reactor building, the river pumphouse and the reactor stack are the only facilities that remain. Today, the U.S. Department of Energy (DOE) Richland Operations Office offers escorted public access to B Reactor along a designated tour route. The National Park Service (NPS) is studying preservation and interpretation options for sites associated with the Manhattan Project. …
Date: April 28, 2009
Creator: MS, GERBER
System: The UNT Digital Library
Hydrological consequences of global warming (open access)

Hydrological consequences of global warming

The 2007 Intergovernmental Panel for Climate Change indicates there is strong evidence that the atmospheric concentration of carbon dioxide far exceeds the natural range over the last 650,000 years, and this recent warming of the climate system is unequivocal, resulting in more frequent extreme precipitation events, earlier snowmelt runoff, increased winter flood likelihoods, increased and widespread melting of snow and ice, longer and more widespread droughts, and rising sea level. The effects of recent warming has been well documented and climate model projections indicate a range of hydrological impacts with likely to very likely probabilities (67 to 99 percent) of occurring with significant to severe consequences in response to a warmer lower atmosphere with an accelerating hydrologic cycle.
Date: June 1, 2009
Creator: Miller, Norman L.
System: The UNT Digital Library
Benefits of Parallel I/O in Ab Initio Nuclear Physics Calculations, ICCS 2009 Proceedings (open access)

Benefits of Parallel I/O in Ab Initio Nuclear Physics Calculations, ICCS 2009 Proceedings

Many modern scientific applications rely on highly parallel calculations, which scale to 10's of thousands processors. However, most applications do not concentrate on parallelizing input/output operations. In particular, sequential I/O has been identified as a bottleneck for the highly scalable MFDn (Many Fermion Dynamics for nuclear structure) code performing ab initio nuclear structure calculations. In this paper, we develop interfaces and parallel I/O procedures to use a well-known parallel I/O library in MFDn. As a result, we gain efficient input/output of large datasets along with their portability and ease of use in the downstream processing.
Date: May 20, 2009
Creator: Laghave, Nikhil; Sosonkina, Masha; Maris, Pieter & Vary, James P.
System: The UNT Digital Library
Industrial Applications Perspective of Nanodielectrics (open access)

Industrial Applications Perspective of Nanodielectrics

The field of nanodielectrics has had a significant impact on voltage endurance characteristics of electrical insulation. Improved time-to-breakdown behavior, resulting in reduced aging of insulation, and enhanced thermal stability are of considerable importance in industrial applications. This chapter discusses several specific aspects of nanodielectrics and their role in the future of electrical insulation and dielectric sciences.
Date: January 1, 2009
Creator: Tuncer, Enis & Sauers, Isidor
System: The UNT Digital Library
Geochip: A high throughput genomic tool for linking community structure to functions (open access)

Geochip: A high throughput genomic tool for linking community structure to functions

GeoChip is a comprehensive functional gene array that targets key functional genes involved in the geochemical cycling of N, C, and P, sulfate reduction, metal resistance and reduction, and contaminant degradation. Studies have shown the GeoChip to be a sensitive, specific, and high-throughput tool for microbial community analysis that has the power to link geochemical processes with microbial community structure. However, several challenges remain regarding the development and applications of microarrays for microbial community analysis.
Date: January 30, 2009
Creator: Van Nostrand, Joy D.; Liang, Yuting; He, Zhili; Li, Guanghe & Zhou, Jizhong
System: The UNT Digital Library
In situ groundwater bioremediation (open access)

In situ groundwater bioremediation

In situ groundwater bioremediation of hydrocarbons has been used for more than 40 years. Most strategies involve biostimulation; however, recently bioaugmentation have been used for dehalorespiration. Aquifer and contaminant profiles are critical to determining the feasibility and strategy for in situ groundwater bioremediation. Hydraulic conductivity and redox conditions, including concentrations of terminal electron acceptors are critical to determine the feasibility and strategy for potential bioremediation applications. Conceptual models followed by characterization and subsequent numerical models are critical for efficient and cost effective bioremediation. Critical research needs in this area include better modeling and integration of remediation strategies with natural attenuation.
Date: February 1, 2009
Creator: Hazen, Terry C.
System: The UNT Digital Library
Thermal neutron imaging in an active interrogation environment (open access)

Thermal neutron imaging in an active interrogation environment

Gain an in-depth understanding of the role of quark flavor.
Date: July 3, 2009
Creator: Jaffe, D. E.; Marciano, W.; Soni, A.; Parsa, Z. & Van de Water,R.
System: The UNT Digital Library
Electronic Structure Calculations and Adaptation Scheme in Multi-core Computing Environments (open access)

Electronic Structure Calculations and Adaptation Scheme in Multi-core Computing Environments

Multi-core processing environments have become the norm in the generic computing environment and are being considered for adding an extra dimension to the execution of any application. The T2 Niagara processor is a very unique environment where it consists of eight cores having a capability of running eight threads simultaneously in each of the cores. Applications like General Atomic and Molecular Electronic Structure (GAMESS), used for ab-initio molecular quantum chemistry calculations, can be good indicators of the performance of such machines and would be a guideline for both hardware designers and application programmers. In this paper we try to benchmark the GAMESS performance on a T2 Niagara processor for a couple of molecules. We also show the suitability of using a middleware based adaptation algorithm on GAMESS on such a multi-core environment.
Date: May 20, 2009
Creator: Seshagiri, Lakshminarasimhan; Sosonkina, Masha & Zhang, Zhao
System: The UNT Digital Library
Experimental Mathematics and Computational Statistics (open access)

Experimental Mathematics and Computational Statistics

The field of statistics has long been noted for techniques to detect patterns and regularities in numerical data. In this article we explore connections between statistics and the emerging field of 'experimental mathematics'. These includes both applications of experimental mathematics in statistics, as well as statistical methods applied to computational mathematics.
Date: April 30, 2009
Creator: Bailey, David H. & Borwein, Jonathan M.
System: The UNT Digital Library
Genomics of Secondary Metabolism in Populus: Interactions With Biotic and Abiotic Environments (open access)

Genomics of Secondary Metabolism in Populus: Interactions With Biotic and Abiotic Environments

Populus trees face constant challenges from the environment during their life cycle. To ensure their survival and reproduction, Populus trees deploy various types of defenses, one of which is the production of a myriad of secondary metabolites. Compounds derived from the shikimate-phenylpropanoid pathway are the most abundant class of secondary metabolites synthesized in Populus. Among other major classes of secondary metabolites in Populus are terpenoids and fatty acid-derivatives. Some of the secondary metabolites made by Populus trees have been functionally characterized. Some others have been associated with certain biological/ecological processes, such as defense against insects and microbial pathogens or acclimation or adaptation to abiotic stresses. Functions of many Populus secondary metabolites remain unclear. The advent of various novel genomic tools will enable us to explore in greater detail the complexity of secondary metabolism in Populus. Detailed data mining of the Populus genome sequence can unveil candidate genes of secondary metabolism. Metabolomic analysis will continue to identify new metabolites synthesized in Populus. Integrated genomics that combines various omics tools will prove to be the most powerful approach in revealing the molecular and biochemical basis underlying the biosynthesis of secondary metabolites in Populus. Characterization of the biological/ecological functions of secondary metabolites as …
Date: January 1, 2009
Creator: Chen, Feng; Liu, Chang-Jun; Tschaplinski, Timothy J & Zhao, Nan
System: The UNT Digital Library
Fluid effects on seismic waves in hard rocks with fractures and in soft granular media (open access)

Fluid effects on seismic waves in hard rocks with fractures and in soft granular media

When fractures in otherwise hard rocks are filled with fluids (oil, gas, water, CO{sub 2}), the type and physical state of the fluid (liquid or gas) can make a large difference in the wave speeds and attenuation properties of seismic waves. The present work summarizes methods of deconstructing theses effects of fractures, together with any fluids contained within them, on wave propagation as observed in reflection seismic data. Additional studies of waves in fluid-saturated granular media show that the behavior can be quite different from that for fractured media, since these materials are typically much softer mechanically than are the fractured rocks (i.e., having a very small drained moduli). Important fluid effects in such media are often governed as much by fluid viscosity as by fluid bulk modulus.
Date: March 1, 2009
Creator: Berryman, James G.
System: The UNT Digital Library
Mathematical models as tools for probing long-term safety of CO2 storage (open access)

Mathematical models as tools for probing long-term safety of CO2 storage

Subsurface reservoirs being considered for storing CO{sub 2} include saline aquifers, oil and gas reservoirs, and unmineable coal seams (Baines and Worden, 2004; IPCC, 2005). By far the greatest storage capacity is in saline aquifers (Dooley et al., 2004), and our discussion will focus primarily on CO{sub 2} storage in saline formations. Most issues for safety and security of CO{sub 2} storage arise from the fact that, at typical temperature and pressure conditions encountered in terrestrial crust, CO{sub 2} is less dense than aqueous fluids. Accordingly, CO{sub 2} will experience an upward buoyancy force in most subsurface environments, and will tend to migrate upwards whenever (sub-)vertical permeable pathways are available, such as fracture zones, faults, or improperly abandoned wells (Bachu, 2008; Pruess, 2008a, b; Tsang et al., 2008). CO{sub 2} injection will increase fluid pressures in the target formation, thereby altering effective stress distributions, and potentially triggering movement along fractures and faults that could increase their permeability and reduce the effectiveness of a caprock in containing CO{sub 2} (Rutqvist et al., 2008; Chiaramonte et al., 2008). Induced seismicity as a consequence of fluid injection is also a concern (Healy et al., 1968; Raleigh et al., 1976; Majer et al., 2007). …
Date: February 1, 2009
Creator: Pruess, Karsten; Birkholzer, Jens & Zhou, Quanlin
System: The UNT Digital Library
Cometabolic bioremediation (open access)

Cometabolic bioremediation

Cometabolic bioremediation is probably the most under appreciated bioremediation strategy currently available. Cometabolism strategies stimulate only indigenous microbes with the ability to degrade the contaminant and cosubstrate e.g. methane, propane, toluene and others. This highly targeted stimulation insures that only those microbes that can degrade the contaminant are targeted, thus reducing amendment costs, well and formation plugging, etc. Cometabolic bioremediation has been used on some of the most recalcitrant contaminants, e.g. PCE, TCE, MTBE, TNT, dioxane, atrazine, etc. Methanotrophs have been demonstrated to produce methane monooxygense, an oxidase that can degrade over 300 compounds. Cometabolic bioremediation also has the advantage of being able to degrade contaminants to trace concentrations, since the biodegrader is not dependent on the contaminant for carbon or energy. Increasingly we are finding that in order to protect human health and the environment that we must remediate to lower and lower concentrations, especially for compounds like endocrine disrupters, thus cometabolism may be the best and maybe the only possibility that we have to bioremediate some contaminants.
Date: February 15, 2009
Creator: Hazen, Terry C.
System: The UNT Digital Library
Exceptional groups, symmetric spaces and applications (open access)

Exceptional groups, symmetric spaces and applications

In this article we provide a detailed description of a technique to obtain a simple parameterization for different exceptional Lie groups, such as G{sub 2}, F{sub 4} and E{sub 6}, based on their fibration structure. For the compact case, we construct a realization which is a generalization of the Euler angles for SU(2), while for the non compact version of G{sub 2(2)}/SO(4) we compute the Iwasawa decomposition. This allows us to obtain not only an explicit expression for the Haar measure on the group manifold, but also for the cosets G{sub 2}/SO(4), G{sub 2}/SU(3), F{sub 4}/Spin(9), E{sub 6}/F{sub 4} and G{sub 2(2)}/SO(4) that we used to find the concrete realization of the general element of the group. Moreover, as a by-product, in the simplest case of G{sub 2}/SO(4), we have been able to compute an Einstein metric and the vielbein. The relevance of these results in physics is discussed.
Date: March 31, 2009
Creator: Cerchiai, Bianca L. & Cacciatori, Sergio L.
System: The UNT Digital Library
OVERVIEW OF BERYLLIUM SAMPLING AND ANALYSIS (open access)

OVERVIEW OF BERYLLIUM SAMPLING AND ANALYSIS

Because of its unique properties as a lightweight metal with high tensile strength, beryllium is widely used in applications including cell phones, golf clubs, aerospace, and nuclear weapons. Beryllium is also encountered in industries such as aluminium manufacturing, and in environmental remediation projects. Workplace exposure to beryllium particulates is a growing concern, as exposure to minute quantities of anthropogenic forms of beryllium may lead to sensitization and to chronic beryllium disease, which can be fatal and for which no cure is currently known. Furthermore, there is no known exposure-response relationship with which to establish a 'safe' maximum level of beryllium exposure. As a result, the current trend is toward ever lower occupational exposure limits, which in turn make exposure assessment, both in terms of sampling and analysis, more challenging. The problems are exacerbated by difficulties in sample preparation for refractory forms of beryllium, such as beryllium oxide, and by indications that some beryllium forms may be more toxic than others. This chapter provides an overview of sources and uses of beryllium, health risks, and occupational exposure limits. It also provides a general overview of sampling, analysis, and data evaluation issues that will be explored in greater depth in the remaining …
Date: April 1, 2009
Creator: Brisson, M
System: The UNT Digital Library
Quantitative Assessment of Robot-generated Maps (open access)

Quantitative Assessment of Robot-generated Maps

Mobile robotic mapping is now considered to be a sufficiently mature field with demonstrated successes in various domains. While much progress has been made in the development of computationally efficient and consistent mapping schemes, it is still murky, at best, on how these maps can be evaluated. We are motivated by the absence of an accepted standard for quantitatively measuring the performance of robotic mapping systems against user-defined requirements. It is our belief that the development of standardized methods for quantitatively evaluating existing robotic technologies will improve the utility of mobile robots in already established application areas, such as vacuum cleaning, robot surveillance, and bomb disposal. This approach will also enable the proliferation and acceptance of such technologies in emerging markets. This chapter summarizes our preliminary efforts by bringing together the research community towards addressing this important problem which has ramifications not only from researchers perspective but also from consumers, robot manufacturers, and developers viewpoints.
Date: January 1, 2009
Creator: Scrapper, Chris; Madhavan, Raj & Lakaemper, Rolf
System: The UNT Digital Library
Hadron Production in Heavy Ion Collisions (open access)

Hadron Production in Heavy Ion Collisions

Heavy ion collisions are an ideal tool to explore the QCD phase diagram. The goal is to study the equation of state (EOS) and to search for possible in-medium modifications of hadrons. By varying the collision energy a variety of regimes with their specific physics interest can be studied. At energies of a few GeV per nucleon, the regime where experiments were performed first at the Berkeley Bevalac and later at the Schwer-Ionen-Synchrotron (SIS) at GSI in Darmstadt, we study the equation of state of dense nuclear matter and try to identify in-medium modifications of hadrons. Towards higher energies, the regime of the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL), the Super-Proton Synchrotron (SPS) at CERN, and the Relativistic Heavy Ion Collider (RHIC) at BNL, we expect to produce a new state of matter, the Quark-Gluon Plasma (QGP). The physics goal is to identify the QGP and to study its properties. By varying the energy, different forms of matter are produced. At low energies we study dense nuclear matter, similar to the type of matter neutron stars are made of. As the energy is increased the main constituents of the matter will change. Baryon excitations will become …
Date: May 19, 2009
Creator: Ritter, Hans Georg & Xu, Nu
System: The UNT Digital Library
Proteomic Insights: Cryoadaption of Permafrost Bacteria (open access)

Proteomic Insights: Cryoadaption of Permafrost Bacteria

The permafrost microbial community has been described as 'a community of survivors' (Friedman 1994). Because of the permanently cold condition and the long term isolation of the permafrost sediments, the permafrost microorganisms have acquired various adaptive features in the membrane, enzymes, and macromolecular synthesis. This chapter reviews the different adaptive mechanisms used by permafrost microorganisms with a focus on the proteomic level of cryoadaptation that have recently been identified during the low temperature growth in permafrost bacteria.
Date: January 1, 2009
Creator: Qiu, Yinghua; Vishnivetskaya, Tatiana A. & Lubman, David M.
System: The UNT Digital Library
CHAPTER 7. BERYLLIUM ANALYSIS BY NON-PLASMA BASED METHODS (open access)

CHAPTER 7. BERYLLIUM ANALYSIS BY NON-PLASMA BASED METHODS

The most common method of analysis for beryllium is inductively coupled plasma atomic emission spectrometry (ICP-AES). This method, along with inductively coupled plasma mass spectrometry (ICP-MS), is discussed in Chapter 6. However, other methods exist and have been used for different applications. These methods include spectroscopic, chromatographic, colorimetric, and electrochemical. This chapter provides an overview of beryllium analysis methods other than plasma spectrometry (inductively coupled plasma atomic emission spectrometry or mass spectrometry). The basic methods, detection limits and interferences are described. Specific applications from the literature are also presented.
Date: April 20, 2009
Creator: Ekechukwu, A
System: The UNT Digital Library
Mass Transport within Soils (open access)

Mass Transport within Soils

Contaminants in soil can impact human health and the environment through a complex web of interactions. Soils exist where the atmosphere, hydrosphere, geosphere, and biosphere converge. Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. A true soil is a mixture of air, water, mineral, and organic components. The relative proportions of these components determine the value of the soil for agricultural and for other human uses. These proportions also determine, to a large extent, how a substance added to soil is transported and/or transformed within the soil (Spositio, 2004). In mass-balance models, soil compartments play a major role, functioning both as reservoirs and as the principal media for transport among air, vegetation, surface water, deeper soil, and ground water (Mackay, 2001). Quantifying the mass transport of chemicals within soil and between soil and atmosphere is important for understanding the role soil plays in controlling fate, transport, and exposure to multimedia pollutants. Soils are characteristically heterogeneous. A trench dug into soil typically reveals several horizontal layers having different colors and textures. As illustrated in Figure 1, these multiple layers are often divided into …
Date: March 1, 2009
Creator: McKone, Thomas E.
System: The UNT Digital Library
Viable Cyanobacteria and Green Algae from the Permafrost Darkness (open access)

Viable Cyanobacteria and Green Algae from the Permafrost Darkness

This review represents an overview of the existence, distribution and abundance of the photoautotrophic microorganisms in the deep subsurface permafrost of the Northeast Russia and McMurdo Dry Valleys, Antarctica. The morphology, growth rate, spectral properties, phylogenetic position of the viable permafrost green algae and cyanobacteria have been studied. Viable photoautotrophs were represented by unicellular green algae and filamentous cyanobacteria with low growth rate. Spectral studies of ancient cyanobacteria and green algae did not reveal any significant differences between them and their contemporary relatives. Phylogenetic analyses have shown that permafrost photoautotrophs were closely related to strains and more often to uncultured environmental clones from cold regions.
Date: January 1, 2009
Creator: Vishnivetskaya, Tatiana A.
System: The UNT Digital Library