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Molecular-Level Investigations of Nucleation Mechanisms and Kinetics of Formation of Environmental Nanoparticles

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.
Date: April 19, 2007
Creator: Jun, Young-Shin & Waychunas, Glenn A.
System: The UNT Digital Library

Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFC Focused on Hanford’s 300 Area Uranium Plume

None
Date: April 19, 2007
Creator: Zachara, J.; Freshley, M.; DePaolo, D.; Fredrickson, J.; Haggerty, R.; Kent, D. et al.
System: The UNT Digital Library

Recommended Library Contributions to Retention of Premedical Students

Poster for the 2015 Medical Library Association Annual Meeting and Exhibition. This poster discusses recommended library contributions to the retention of premedical students.
Date: May 19, 2015
Creator: O'Toole, Erin
System: The UNT Digital Library

Synthesis of Goethite-Coated Sand and Analysis of its Interactions with Uranium

None
Date: April 19, 2007
Creator: Loganathan, Vijay A.; Kanel, Sushil R.; Barnett, Mark O. & Clement, and T. Prabhakar
System: The UNT Digital Library

Mesoscale Biotransformation of Uranium: Influences of Organic Carbon Supply Rates and Sediment Oxides

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.
Date: April 19, 2007
Creator: Tokunaga, Tetsu; Wan, Jiamin; Kim, Yongman; Daly, Rebecca; Brodie, Eoin; Firestone, Mary et al.
System: The UNT Digital Library

Promoting Uranium Immobilization by the Activities of Microbial Phosphatases

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 …
Date: April 19, 2007
Creator: Martinez, Robert J.; Beazley, Melanie J.; Webb, Samuel M.; Taillefert, Martial & Sobecky, Patricia A.
System: The UNT Digital Library

Kinetic Controls on the Desorption/Dissolution of Sorbed U(VI) and Their Influence on Reactive Transport

None
Date: April 19, 2007
Creator: Zachara, J. M.; Liu, C.; Qafoku, N.; McKinley, J. P.; Davis, J. A.; Stoliker, D. et al.
System: The UNT Digital Library

Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales

None
Date: April 19, 2007
Creator: Kanel, S. R.; Loganathan, V. A.; Jeppu, G.; Kumar, A.; Srinivasan, V.; Radu, T. et al.
System: The UNT Digital Library

Mechanistically-Based Field-Scale Models of Uranium Biogeochemistry from Upscaling Pore-Scale Experiments and Models

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 …
Date: April 19, 2007
Creator: Scheibe, Tim; Tartakovsky, Alexandre; Wood, Brian & Seymour, Joe
System: The UNT Digital Library

Applying EMSL Capabilities to Biogeochemistry and Environmental Research

The Environmental Molecular Sciences laboratory (EMSL) is a national scientific user facility operated by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy's Office of Biological and Environmental Research. Located in Richland, Washington, EMSL offers researchers a comprehensive array of cutting-edge capabilities unmatched anywhere else in the world and access to the expertise of over 300 resident users--all at one location. EMSL's resources are available on a peer-reviewed proposal basis and are offered at no cost if research results are shared in the open literature. Researchers are encouraged to submit a proposal centered around one of EMSL's four Science Themes, which represent growing areas of research: (1) Geochemistry/Biogeochemistry and Subsurface Science; (2) Atmospheric Aerosol Chemistry; (3) Biological Interactions and Dynamics; and (4) Science of Interfacial Phenomena. To learn more about EMSL, visit www.emsl.pnl.gov.
Date: April 19, 2007
Creator: Felmy, Andy
System: The UNT Digital Library

Changes in Microbial Community Structure During Biostimulation for Uranium Reduction at Different Levels of Resolution

This poster describes the Changes in Microbial Community Structure During Biostimulation for Uranium Reduction at Different Levels of Resolution
Date: April 19, 2007
Creator: Hwang, C.; Wu, W.-M.; Gentry, T.J.; Corbin, G.; Carley, J.; Carroll, S.L. et al.
System: The UNT Digital Library

Coupled Processes Influencing the Transport of Uranium over Multiple Scales

None
Date: April 19, 2007
Creator: Mayes, Melanie A.; Tang, Guoping; Parker, Jack C.; Perfect, Ed & van den Berg, Elmer
System: The UNT Digital Library

Influence of Wetting and Mass Transfer Properties of Organic Chemical Mixtures in Vadose Zone Materials on Groundwater Contamination by Nonaqueous Phase Liquids

None
Date: April 19, 2007
Creator: Werth, Charles; Valocchi, Albert; Yoon, Hongkyu; Nellis, Scott; Prescod, Garvin & Oostrom, Mart
System: The UNT Digital Library

Biogeochemical Mechanisms Controlling Reduced Radionuclide Particle Properties and Stability

None
Date: April 19, 2007
Creator: Marshall, M.J.; Beliaev, A.S.; Fredrickson, J.K. & Zachara, J.M
System: The UNT Digital Library

The Center for Environmental Kinetics Analysis: an NSF- and DOE-funded Environmental Molecular Science Institute (EMSI) at Penn State

Physicochemical and microbiological processes taking place at environmental interfaces influence natural processes as well as the transport and fate of environmental contaminants, the remediation of toxic chemicals, and the sequestration of anthropogenic CO2. A team of scientists and engineers has been assembled to develop and apply new experimental and computational techniques to expand our knowledge of environmental kinetics. We are also training a cohort of talented and diverse students to work on these complex problems at multiple length scales and to compile and synthesize the kinetic data. Development of the human resources capable of translating molecular-scale information into parameters that are applicable in real world, field-scale problems of environmental kinetics is a major and relatively unique objective of the Institute's efforts. The EMSI team is a partnership among 10 faculty at The Pennsylvania State University (funded by the National Science Foundation Divisions of Chemistry and Earth Sciences), one faculty member at Juniata College, one faculty member at the University of Florida, and four researchers drawn from Los Alamos National Laboratory, Pacific Northwest National Laboratory, and Lawrence Berkeley National Laboratory (funded by the Department of Energy Division of Environmental Remediation Sciences). Interactions among the applied and academic scientists drives research approaches …
Date: April 19, 2007
Creator: Brantley, S. L.; Burgos, William D.; Dempsey, Brian A.; Heaney, Peter J.; Kubicki, James D.; Lichtner, Peter C. et al.
System: The UNT Digital Library

Thermodynamic network model for predicting effects of substrate addition and other perturbations on subsurface microbial communities

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.
Date: April 19, 2007
Creator: Istok, Jack; Park, Melora; McKinley, James; Liu, Chongxuan; Krumholz, Lee; Spain, Anne et al.
System: The UNT Digital Library

Isotopic Tracers for Biogeochemical Processes and Contaminant Transport: Hanford, Washington

Our goal is to use isotopic measurements to understand how contaminants are introduced to and stored in the vadose zone, and what processes control migration from the vadose zone to groundwater and then to surface water. We have been using the Hanford Site in south-central Washington as our field laboratory, and our investigations are often stimulated by observations made as part of the groundwater monitoring program and vadose zone characterization activities. Understanding the transport of contaminants at Hanford is difficult due to the presence of multiple potential sources within small areas, the long history of activities, the range of disposal methods, and the continuing evolution of the hydrological system. Observations often do not conform to simple models, and cannot be adequately understood with standard characterization approaches, even though the characterization activities are quite extensive. One of our objectives is to test the value of adding isotopic techniques to the characterization program, which has the immediate potential benefit of addressing specific remediation issues, but more importantly, it allows us to study fundamental processes at the scale and in the medium where they need to be understood. Here we focus on two recent studies at the waste management area (WMA) T-TX-TY, which …
Date: April 19, 2007
Creator: DePaolo, Donald J.; Christensen, John N.; Conrad, Mark E. & Dresel, and P. Evan
System: The UNT Digital Library

Stabilization of Plutonium in Subsurface Environments via Microbial Reduction and Biofilm Formation

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+.
Date: April 19, 2007
Creator: Boukhalfa, Hakim; Icopini, Gary A.; Reilly, Sean D. & Neu, Mary P.
System: The UNT Digital Library

Newsmap. Monday, July 19, 1943 : week of July 8 to July 15, 201st week of the war, 83rd week of U.S. participation

Front: Text describes action on various war fronts: Sicily, Air offensive, Russia, New Georgia, New Guinea, Aleutians, Submarines. Includes list of senior commanders in the Invasion of Italy. Maps: New Georgia Islands; American 7th army positions in Licata and Vittoria Italy. Inset map: Italy and surrounding islands. Illustration: Landing on the underside [Allied air attack on ships unloading military cargo on the beaches of Southern Sicily]. Back: Text and color illustrations include various methods of enemy gas applications.
Date: July 19, 1943
Creator: [United States.] Army Orientation Course.
System: The UNT Digital Library

More Than Just a Degree: Preparing Graduate Library Students For Their Future

This poster outlines the recent restructure of the Graduate Library Assistant Program at the University of North Texas Libraries.
Date: April 19, 2016
Creator: Keshmiripour, Setareh & Zerangue, Amanda
System: The UNT Digital Library

Chicken-Scratch Decoded: Deciphering Professor Signatures for Improved Discoverability of ETDs

This poster describes the process for deciphering professor signatures for improved discoverability of ETDs.
Date: April 19, 2016
Creator: Wolf, Stacey & Yanowski, Kevin
System: The UNT Digital Library

[Poster for Blues on 125th Street]

Poster for the play Blues on 125th Street, performed by the Third World Players, written by Bob Ray Sanders, and directed by Curtis L. King. The play was performed on November 19, 1978 at the Dallas Convention Center Theater.
Date: November 19, 1978
Creator: Junior Black Academy of Arts and Letters
System: The UNT Digital Library

Newsmap. Monday, April 19, 1943 : week of April 9 to April 16, 188th week of the war, 70th week of U.S. participation

Front: Text describes action on various war fronts: Tunisia -- Southwest Pacific -- Russia -- Mediterranean. Large world map is keyed to text and illustrates time zones around the world. Inset maps show Allied drive in Tunisia -- Japanese controlled areas throughout the Southwest Pacific. Includes photographs: Helping Rommel's run [puppy stationed atop a Vickers machine gun] -- So he can fight (Staff Sergt. Hollers clerks at the San Angelo AAF Bombardier School in Texas) -- Blimp training. Back: Tunisia, map with inset showing location of Tunisia in the Mediterranean area.
Date: April 19, 1943
Creator: [United States.] Army Orientation Course.
System: The UNT Digital Library