Effective environmental management of DOE sites requires reliable prediction of reactive transport phenomena. A central issue in prediction of subsurface reactive transport is the impact of multiscale physical, chemical, and biological heterogeneity. Heterogeneity manifests itself through incomplete mixing of reactants at scales below those at which concentrations are explicitly defined (i.e., the numerical grid scale). This results in a mismatch between simulated reaction processes (formulated in terms of average concentrations) and actual processes (controlled by local concentrations). At the field scale, this results in apparent scale-dependence of model parameters and inability to utilize laboratory parameters in field models. Accordingly, most field modeling efforts are restricted to empirical estimation of model parameters by fitting to field observations, which renders extrapolation of model predictions beyond fitted conditions unreliable. The objective of this project is to develop a theoretical and computational framework for (1) connecting models of coupled reactive transport from pore-scale processes to field-scale bioremediation through a hierarchy of models that maintain crucial information from the smaller scales at the larger scales; and (2) quantifying the uncertainty that is introduced by both the upscaling process and uncertainty in physical parameters. One of the challenges of addressing scale-dependent effects of coupled processes in …

Remediation and long-term stewardship of uranium-contaminated sediments and groundwaters are critical problems at a number of DOE facilities and mining sites. Some remediation strategies based on in-situ bioreduction of U are potentially effective in significantly decreasing U concentrations in groundwaters. However, a number of basic processes require understanding in order to identify conditions more conducive to success of reduction-based U stabilization. Our current research targets several of these issues including: (1) effects of organic carbon (OC) forms and supply rates on stability of bioreduced U, (2) the roles of Fe(III)- and Mn(III,IV)-oxides as potential U oxidants in sediments, and (3) microbial community changes in relation to U redox changes. These issues were identified in our previous study on U bioreduction and reoxidation (Wan et al., 2005). Most of our studies are being conducted on historically U-contaminated sediments from Area 2 of the Field Research Center, Oak Ridge National Laboratory, in flow-through columns simulating in-situ field remediation.

Environmental nanoparticles are often poorly-crystalline or metastable structures, whose kinetics of formation and growth are poorly understood. Further, the sorption or growth of nanoparticles on mineral surfaces may control the mineral surface's reactivity and modify its ability to influence contaminant transport. Due to the characteristic length scale, a holistic understanding of the nucleation mechanisms and kinetics of nanoparticle formation on mineral surfaces is difficult to achieve with traditional methodology. In this work, our intent is to determine the molecular nature of nucleation on surfaces, the kinetics of surface nucleation and growth, and the effect of crystal surface topology using new synchrotron-based techniques. We have approached these objectives by: (1) combining state-of-the-art crystal-truncation rod diffraction (CTR) and grazing incidence x-ray absorption fine structure spectroscopy (GIXAS) techniques to investigate the three-dimensional molecular-scale geometry of silicate monomer sorption on the r-plane of hematite; and (2) developing a new grazing-incidence small angle x-ray scattering (GISAXS) setup at SSRL (0.08 nm{sup -1} < q < 8 nm{sup -1}) to explore the initial development of environmental nanoparticles on various mineral surfaces. This study also includes complementary techniques such as atomic force microscopy (AFM), bulk SAXS, dynamic light scattering (DLS), XRD, and TEM.

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The overall objective of this project is to examine the activity of nonspecific phosphohydrolases present in naturally occurring subsurface microorganisms for the purpose of promoting the immobilization of radionuclides through the production of uranium [U(VI)] phosphate precipitates. Specifically, we hypothesize that the precipitation of U(VI) phosphate minerals may be promoted through the microbial release and/or accumulation of PO4 3- as a means to detoxify radionuclides and heavy metals. An experimental approach was designed to determine the extent of phosphatase activity in bacteria previously isolated from contaminated subsurface soils collected at the ERSP Field Research Center (FRC) in Oak Ridge, TN. Screening of 135 metal resistant isolates for phosphatase activity indicated the majority (75 of 135) exhibited a phosphatase-positive phenotype. During this phase of the project, a PCR based approach has also been designed to assay FRC isolates for the presence of one or more classes of the characterized non-specific acid phophastase (NSAP) genes likely to be involved in promoting U(VI) precipitation. Testing of a subset of Pb resistant (Pbr) Arthrobacter, Bacillus and Rahnella strains indicated 4 of the 9 Pbr isolates exhibited phosphatase phenotypes suggestive of the ability to bioprecipitate U(VI). Two FRC strains, a Rahnella sp. strain Y9602 and …

Plutonium has a long half-life (2.4 x 104 years) and is of concern because of its chemical and radiological toxicity, high-energy alpha radioactive decay. A full understanding of its speciation and interactions with environmental processes is required in order to predict, contain, or remediate contaminated sites. Under aerobic conditions Pu is sparingly soluble, existing primarily in its tetravalent oxidation state. To the extent that pentavalent and hexavalent complexes and small colloidal species form they will increase the solubility and resultant mobility from contamination sources. There is evidence that in both marine environments and brines substantial fractions of the plutonium in solution is present as hexavalent plutonyl, PuO2 2+.

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The overall goal of this project is to develop and test a thermodynamic network model for predicting the effects of substrate additions and environmental perturbations on microbial growth, community composition and system geochemistry. The hypothesis is that a thermodynamic analysis of the energy-yielding growth reactions performed by defined groups of microorganisms can be used to make quantitative and testable predictions of the change in microbial community composition that will occur when a substrate is added to the subsurface or when environmental conditions change.

Poster presentation for the 2007 University Scholars Day at the University of North Texas discussing research on hereditary factors in the development of myopia.

This poster examines the relationships between gender differentiated HIV-related coping strategies and depression.

Poster/flyer advertising a concert by The Naptime Shake with Matt Bauer and Garrett Pierce on March 20, 2007, at Secret Headquarters in Denton, TX. Poster depicts a red pterodactyl against an off white background carrying a guitar in its mouth flying down to a nest in a tree with two, red pterodactyl babies. Event information is in red text at the bottom of the poster.

Event flyer for Choctaw History, hosted by the University of North Texas Multicultural Center that was held in the University's Union building, Room 417 on March 7, 2007 at 2:00 pm.

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Parabolic trough receivers, or heat collection elements (HCEs), absorb sunlight focused by the mirrors and transfer that thermal energy to a fluid flowing within them. Thje absorbing tube of these receivers typically operates around 400 C (752 F). HCE manufacturers prevent thermal loss from the absorbing tube to the environment by using sputtered selective Cermet coatings on the absorber and by surrounding the absorber with a glass-enclosed evacuated annulus. This work quantifies the heat loss of the Solel UVAC2 and Schott PTR70 HCEs. At 400 C, the HCEs perform similarly, losing about 400 W/m of HCE length. To put this in perspective, the incident beam radiation on a 5 m mirror aperture is about 4500 W/m, with about 75% of that energy ({approx} 3400 W/m) reaching the absorber surface. Of the 3400 W/m on the absorber, about 3000 W/m is absorbed into the working fluid while 400 W/m is lost to the environment.

A poster advertising the school breakfast week Olympics, March 5-9th.

Poster/flyer advertising the concert lineup at Rubber Gloves Rehearsal Studios in Denton, TX from January 18-May 10, 2007.

Poster presented at the 2007 International Conference on Open Repositories. This poster discusses the Metadata Education and Research Information Commons (MERIC). MERIC originated from an action plan of the Library of Congress and addresses the need to prepare future information professionals to organize and provide access to digital resources.

Poster advertising a concert by Dust Congress, Lil Tedly, Nevada/Seth, Low Red Land, and Chief Death Rage on November 1, 2007, at Strawberry Fields, Denton, Texas. Poster features hand-drawn block lettering and geometric and figurative illustrations over a split-fountain red and pink background.

Poster advertising a concert by Dust Congress, Nouns Group, and Zanzibar Snails on October 11, 2007, at The Public Trust, Dallas, Texas. Poster by artist Nevada Hill features hand-drawn lettering and illustration in red and brown ink on cream paper. The event billed as "Egg Tooth Hatch Party" was on the occasion of the release of Dust Congress' EP, Egg Tooth.

Poster presented at the 2007 ASIS&T Annual Conference. This poster describes the University of North Texas (UNT) Libraries' digital libraries implementations experience. It discusses various scenarios and strategies for integrating controlled vocabularies in the uncontrolled digital library world.

Poster advertising a concert by Lebanon, L'il Tedly, and Jetscreamer on March 19, 2007, at J&J's Pizza, 118 W. Oak, Denton, Texas. Poster features an image of black silhouetted hands centrally converging on a white background with event details overlaid in dark pink text.

This document provides information on how to divide ones plate or tray healthily.

Poster advertising a concert by The Paper Chase, This Was the Year to Lose Friends, and Memorize on Monday, January 22, 2007, at The Conservatory, Oklahoma City, Oklahoma. Poster features an illustration of an antlered girl standing atop a car in a junkyard, surrounded by trees and fireflies at night, printed in shades of blue, black and white.

Poster advertising the Parade of Flesh x-mas party on December 20, 2007 , at City Tavern, Dallas, Texas, with music performances by Antelope, Attractive & Popular, Balthazar, and El Paso Hot Button. Poster features an illustration of a pink abstract amorphous form with speech bubbles containing the event information in purple text.