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Full-Text Articles in Engineering

Next Generation Biofuels And Advanced Engines For Tomorrow’S Transportation Needs, Sandia National Laboratories, Doe Combustion Research Facility, Doe Joint Bioenergy Institute Nov 2009

Next Generation Biofuels And Advanced Engines For Tomorrow’S Transportation Needs, Sandia National Laboratories, Doe Combustion Research Facility, Doe Joint Bioenergy Institute

US Department of Energy Publications

In November 2009, Sandia National Laboratories hosted the Next Generation Biofuels and Advanced Engines for Tomorrow’s Transportation Needs Workshop. The event focused on the combined opportunities in biofuels and engines in the transportation sector. The workshop brought together the DOE Combustion Research Facility and the DOE Joint BioEnergy Institute along with oil companies, biofuel developers, engine manufacturers, suppliers, and experts from the university, regulatory, finance, and national laboratory communities. The intersection of biofuels and engines, if properly scaled, can meet a triad of national goals:

• Reduced climate impact

• Economic development

• Energy security through energy diversity

The workshop …


Nutrient And Bacterial Transport In Runoff From Soil And Pond Ash Amended Feedlot Surfaces, John E. Gilley, Jason R. Vogel, Elaine D. Berry, Roger Eigenberg, David B. Marx, Brian L. Woodbury Nov 2009

Nutrient And Bacterial Transport In Runoff From Soil And Pond Ash Amended Feedlot Surfaces, John E. Gilley, Jason R. Vogel, Elaine D. Berry, Roger Eigenberg, David B. Marx, Brian L. Woodbury

Department of Biological Systems Engineering: Papers and Publications

The addition of pond ash (fly ash that has been placed in evaporative ponds and subsequently dewatered) to feedlot surfaces provides a healthier environment for livestock and economic advantages for the feedlot operator. However, the water quality effects of pond ash amended surfaces are not well understood. The objectives of this field investigation were to: (1) compare feedlot soil properties, and nutrient and bacterial transport in runoff, from pond ash amended surfaces and soil surfaces; (2) compare the effects of unconsolidated surface materials (USM) (loose manure pack) and consolidated subsurface materials (CSM) (compacted manure and underlying layers) on nutrient and …


Cut Crop Edge Detection Using A Laser Sensor, Santosh Pitla, Joe D. Luck, Scott A. Shearer Jun 2009

Cut Crop Edge Detection Using A Laser Sensor, Santosh Pitla, Joe D. Luck, Scott A. Shearer

Department of Biological Systems Engineering: Conference Presentations and White Papers

An off-the-shelf low cost laser sensor was tested and evaluated both in laboratory and field conditions. The sensor identified the angular and straight edges of the laboratory test surface and replicated the straight edge profile with an error of 4%. In field conditions, the sensor identified three types of cut crop edges (wheat, alfalfa and corn) and replicated distinct shapes (triangle, curved and rectangular edges). The sensor was tested at two sensor path offset distances and three tractor/sensor speeds (3.2, 6.4 and 9.6 km/h). In all test runs the sensor detected the cut-crop edges. Standard deviations and RMSE values in …


Development Of Gis-Based Chemical Distribution Maps From Sprayer Performance Data, Joe D. Luck, Santosh Pitla, Rodrigo S. Zandonadi, Scott A. Shearer Jun 2009

Development Of Gis-Based Chemical Distribution Maps From Sprayer Performance Data, Joe D. Luck, Santosh Pitla, Rodrigo S. Zandonadi, Scott A. Shearer

Department of Biological Systems Engineering: Conference Presentations and White Papers

Pesticide application is an essential practice on farms in Kentucky where glyphosate resistant crops and no-till farming strategies are becoming more popular. Off-rate pesticide application errors are the result of incorrect concentrations applied to an area of the field and may result from velocity changes along the spray boom while the sprayer is turning, pressure changes across the width of the spray boom, and changes in effective boom height due to undulating terrain. In an attempt to estimate potential errors resulting from sprayer turning movements, a method was developed to compare the differences in application areas between control sections across …


Guidance Directrix Generation Using Laser Sensors, Santosh Pitla, Joe D. Luck, Scott A. Shearer Jun 2009

Guidance Directrix Generation Using Laser Sensors, Santosh Pitla, Joe D. Luck, Scott A. Shearer

Department of Biological Systems Engineering: Conference Presentations and White Papers

A sensor array consisting of two laser sensors was utilized to determine the guidance directrix (offset distance-d, heading angle-ø) that are required as reference inputs for an automated guidance system. The sensor array was evaluated in both laboratory and field conditions. Under laboratory conditions the sensor array replicated the physical profile of the target surface with a 4% error in determining the heading angle. Field tests were conducted in two types of crops; corn and alfalfa. The sensor array identified the cut-crop edge profile ahead of the tractor and replicated distinct shapes of the cut-crop edge. RMSE values in determining …


Evaluation Of A Terrain Attribute Model For Locating Areas Suitable For Grassed Waterways In Agricultural Settings, Joe D. Luck, Adam C. Pike, Santosh Pitla, Tom Mueller, Scott A. Shearer Jun 2009

Evaluation Of A Terrain Attribute Model For Locating Areas Suitable For Grassed Waterways In Agricultural Settings, Joe D. Luck, Adam C. Pike, Santosh Pitla, Tom Mueller, Scott A. Shearer

Department of Biological Systems Engineering: Conference Presentations and White Papers

Grassed waterways placed in high water flow zones substantially reduce erosion in agricultural fields. A recent study proposed a statistical model for waterway planning for a farm in the Outer Bluegrass physiographic region of Kentucky. The logistic regression model identified where channel erosion was likely to occur based on elevation-derived terrain attributes. The objective of this study was to test their model in fields located in the Western Coal Fields physiographic region where soils differ substantially. Model predictions corresponded well with known areas of concentrated flow (i.e., maps of existing waterways, surface drains, and observations of erosion). The geographic inference …


Preferential Flow Path Effects On Subsurface Contaminant Transport In Alluvial Floodplains, Derek M. Heeren, Ronald B. Miller, Gary A. Fox, Daniel E. Storm, Chad J. Penn, Todd Halihan Jun 2009

Preferential Flow Path Effects On Subsurface Contaminant Transport In Alluvial Floodplains, Derek M. Heeren, Ronald B. Miller, Gary A. Fox, Daniel E. Storm, Chad J. Penn, Todd Halihan

Department of Biological Systems Engineering: Papers and Publications

For strongly sorbing contaminants, transport from upland areas to surface water systems is typically considered to be due to surface runoff with subsurface transport assumed negligible. However, certain local conditions can lead to an environment where subsurface transport to streams may be significant, a source of contamination not alleviated by current best management practices (e.g. riparian buffers). The Ozark region, including parts of Oklahoma, Arkansas, and Missouri, is characterized by cherty, gravelly soils and gravel bed streams. Previous research identified a preferential flow path (PFP) at a field site along the Barren Fork Creek in northeastern Oklahoma. With the subsoils …


Perspectives On Energy Policy: Security, Economics, And The Environment, Sandia National Laboratories Mar 2009

Perspectives On Energy Policy: Security, Economics, And The Environment, Sandia National Laboratories

US Department of Energy Publications

On March 18 and 19, 2009, Sandia National Labo­ratories and the University of California San Diego (UCSD) Sustainability Solutions Institute (SSI) brought together 27 leaders from academia, govern­ment, and the private sector to discuss key energy policy issues and proposed values- and outcomes-based approaches to energy policy. The goal of the workshop was to bring together leaders from diverse backgrounds to identify promising areas for energy policy, based on the understanding of intersecting issues, assumptions, and priorities from the national security, economic, and environmental perspectives.

Participants: Charles Kennel, University of California, San Diego; Les Shephard, Sandia National Laboratories; Michael Aimone, …


Adsorption And Desorption Of Phosphorus And Nitrogen By Immersed Stalks, John E. Gilley, Bahman Eghball, David B. Marx Mar 2009

Adsorption And Desorption Of Phosphorus And Nitrogen By Immersed Stalks, John E. Gilley, Bahman Eghball, David B. Marx

Department of Biological Systems Engineering: Papers and Publications

Adsorption and desorption of phosphorus (P) and nitrogen (N) by stalk residues may influence the concentrations of P and N in runoff. A laboratory study was conducted to measure the effects of P and N constituents in solution on adsorption and desorption of P and N by corn, soybean, and wheat stalk residues. Experimental variables included type of stalk material (corn, soybean, and wheat), inorganic nutrients in solution (PO4-P and NO3-N; PO4-P and NH4-N; NO3-N and NH4-N; and PO4-P, NO3-N, and NH4-N), …


90-Billion Gallon Biofuel Deployment Study -- Executive Summary, Sandia National Laboratories Feb 2009

90-Billion Gallon Biofuel Deployment Study -- Executive Summary, Sandia National Laboratories

US Department of Energy Publications

This study concludes that 90 billion gallons per year of biomass-derived ethanol can be produced and distributed with enduring government commitment and continued technological progress. Specifically, the model projects that 90 billion gallons of ethanol can be produced per year in the U.S.: 15 billion gallons per year from corn ethanol, with the balance from cellulosic ethanol.


Recovery Of Biodiesel Precursors From Heterotrophic Microalga Chlorella Protothecoides, Peter B. Merkle Jan 2009

Recovery Of Biodiesel Precursors From Heterotrophic Microalga Chlorella Protothecoides, Peter B. Merkle

US Department of Energy Publications

This working paper describes an experimental program to assess the suitability of largescale separation processing of algal biomass in aqueous culture. It assumes the possibility of successful large-scale growth of heterotrophic Chlorella protothecoides to produce algal lipid/free fatty acid (FFA) biodiesel precursors.


Reduction And Long-Term Immobilization Of Technetium By Fe(Ii) Associated With Clay Mineral Nontronite, Deb Jaisi, Hailiang Dong, Andrew Plymale, James K. Fredrickson, John M. Zachara, Steve Heald, Chongxuan Liu Jan 2009

Reduction And Long-Term Immobilization Of Technetium By Fe(Ii) Associated With Clay Mineral Nontronite, Deb Jaisi, Hailiang Dong, Andrew Plymale, James K. Fredrickson, John M. Zachara, Steve Heald, Chongxuan Liu

US Department of Energy Publications

99Tc is formed mostly during nuclear reactions and is released into the environment during weapons testing and inadvertent waste disposal. The long half-life, high environmental mobility (as Tc(VII)O4) and its possible uptake into the food chain cause 99Tc to be a significant environmental contaminant. In this study, we evaluated the role of Fe(II) in biologically reduced clay mineral, nontronite (NAu-2), in reducing Tc(VII) O4 to poorly soluble Tc(IV) species as a function of pH and Fe(II) concentration. The rate of Tc(VII) reduction by Fe(II) in NAu-2 was higher at neutral pH (pH 7.0) …


Uranium Speciation As A Function Of Depth In Contaminated Hanford Sediments - A Micro-Xrf, Micro-Xrd, And Micro- And Bulk-Xafs Study, David Singer, John M. Zachara, Gordon Brown Jan 2009

Uranium Speciation As A Function Of Depth In Contaminated Hanford Sediments - A Micro-Xrf, Micro-Xrd, And Micro- And Bulk-Xafs Study, David Singer, John M. Zachara, Gordon Brown

US Department of Energy Publications

The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (μXRF) imaging, micro-X-ray absorption near edge structure (μXANES) spectroscopy, and micro-X-ray diffraction (μXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table …


Electronic Inhomogeneity And Ag:Sb Imbalance Of Ag1−Ypb18sb1+Zte20 High-Performance Thermoelectrics Elucidated By 125te And 207pb Nmr, E. M. Levin, B. A. Cook, K. Ahn, M. G. Kanatzidis, Ames Laboratory Doe Jan 2009

Electronic Inhomogeneity And Ag:Sb Imbalance Of Ag1−Ypb18sb1+Zte20 High-Performance Thermoelectrics Elucidated By 125te And 207pb Nmr, E. M. Levin, B. A. Cook, K. Ahn, M. G. Kanatzidis, Ames Laboratory Doe

US Department of Energy Publications

Using magic-angle spinning 125Te and 207Pb NMR, we have discovered the presence of two phases of approximately tenfold different free-electron concentration, n, in high-performance thermoelectrics Ag1−yPb18Sb1+zTe20 (“LAST-18”), proven by pairs of Knight-shifted NMR peaks and biexponential spin-lattice relaxation. The ratio of the phases is typically 2:1 with n ≈ 2 × 1019 cm−3 and 0.2 × 1019 cm−3, respectively, determined from the spin-lattice relaxation times. 125Te NMR spectra show that both phases contain similar concentrations of Sb. The low-n component is assigned to …


Gathering Cows Using Virtual Fencing Methodologies, Dean M. Anderson, Marek Doniec, Carrick Detweiler, Iuliu Vesilescu, Daniela Rus, Barbara Nolen, Roy Libeau Jan 2009

Gathering Cows Using Virtual Fencing Methodologies, Dean M. Anderson, Marek Doniec, Carrick Detweiler, Iuliu Vesilescu, Daniela Rus, Barbara Nolen, Roy Libeau

CSE Conference and Workshop Papers

Free-ranging livestock are classically controlled by herders. Holding, moving, or gathering free-ranging cattle requires flexible husbandry practices for efficient and effective lowstress animal management. Behavioral theory and practical experience indicates cattle can be taught to respond to auditory cues. Preliminary research has demonstrated that cows can be gathered autonomously using recorded audio cues associated with manual gathering. However, efficient gathering requires movement in the proper direction. Therefore, we believe using audio cues administered from directional virtual fencing (DVF™) equipment can facilitate proper animal orientation and facilitate the gathering of animals with minimal human intervention. Results from applying directional audio cues …


Farming Systems Education: Case Study Of Swedish Test Pilots, Lennart Salomonsson, Anna Nilsson, Sofia Palmer, Adam Roigart, Charles A. Francis Jan 2009

Farming Systems Education: Case Study Of Swedish Test Pilots, Lennart Salomonsson, Anna Nilsson, Sofia Palmer, Adam Roigart, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

We describe and analyze a pedagogical experiment that introduced a broad and holistic perspective on complete farming systems, systemic learning tools, and a participatory learning strategy at an early stage in agronomy education. The paper describes the adventure of three students, who came from a conventional agronomy program at the Swedish University of Agricultural Sciences (SLU), who were frustrated with the lack of integrated approaches to the study of agricultural systems and a strong focus on molecular-level processes in their first year of education. They encountered a narrow focus in most courses and the overall curricula of agricultural education that …


Biomineralization Associated With Microbial Reduction Of Fe3+ And Oxidation Of Fe2+ In Solid Minerals, Gengxin Zhang, Hailiang Dong, Hongchen Jiang, Ravi K. Kukkadapu, Jinwook Kim, Dennis Eberl, Zhiqin Xu Jan 2009

Biomineralization Associated With Microbial Reduction Of Fe3+ And Oxidation Of Fe2+ In Solid Minerals, Gengxin Zhang, Hailiang Dong, Hongchen Jiang, Ravi K. Kukkadapu, Jinwook Kim, Dennis Eberl, Zhiqin Xu

US Department of Energy Publications

Iron-reducing and oxidizing microorganisms gain energy through reduction or oxidation of iron, and by doing so play an important role in the geochemical cycling of iron. This study was undertaken to investigate mineral transformations associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals. A fluid sample from the 2450 m depth of the Chinese Continental Scientific Drilling project was collected, and Fe3+-reducing and Fe2+-oxidizing microorganisms were enriched. The enrichment cultures displayed reduction of Fe3+ in nontronite and ferric citrate, and oxidation of Fe2+ in vivianite, siderite, and monosulfide …


Uranium Extraction From Laboratory-Synthesized, Uranium-Doped Hydrous Ferric Oxides, Steven Smith, Matthew Douglas, Dean A. Moore, Ravi K. Kukkadapu, Bruce Arey Jan 2009

Uranium Extraction From Laboratory-Synthesized, Uranium-Doped Hydrous Ferric Oxides, Steven Smith, Matthew Douglas, Dean A. Moore, Ravi K. Kukkadapu, Bruce Arey

US Department of Energy Publications

The extractability of uranium (U) from synthetic uranium-hydrous ferric oxide (HFO) coprecipitates has been shown to decrease as a function of mineral ripening, consistent with the hypothesis that the ripening process will decrease uranium lability. To evaluate this process, three HFO suspensions were coprecipitated with uranyl (UO22+) and maintained at pH 7.0 ± 0.1. Uranyl was added to the HFO post-precipitation in a fourth suspension. Two suspensions also contained either coprecipitated silicate(Si-U-HFO) or phosphate (P-U-HFO).After precipitation of the HFOs, at time intervals of 1 week, 1 month, 6 months, 1 year, and 2 years, aliquots of each …


Uranium In Framboidal Pyrite From A Naturally Bioreduced Alluvial Sediment, Nikolla P. Qafoku, Ravi K. Kukkadapu, James P. Mckinley, Bruce W, Arey, Shelly D. Kelly, Chongmin Wang, Charles T. Resch, Philip E. Long Jan 2009

Uranium In Framboidal Pyrite From A Naturally Bioreduced Alluvial Sediment, Nikolla P. Qafoku, Ravi K. Kukkadapu, James P. Mckinley, Bruce W, Arey, Shelly D. Kelly, Chongmin Wang, Charles T. Resch, Philip E. Long

US Department of Energy Publications

Samples of a naturally bioreduced, U-contaminated alluvial sediment were characterized with various microscopic and spectroscopic techniques and wet chemical extraction methods. The objective was to investigate U association and interaction with minerals of the sediment. Bioreduced sediment comprises ∼10% of an alluvial aquifer adjacent to the Colorado River, in Rifle, CO, that was the site of a former U milling operation. Past and ongoing research has demonstrated that bioreduced sediment is elevated in solid-associated U, total organic carbon, and acid-volatile sulfide, and depleted in bioavailable Fe(III) confirming that sulfate and Fe(III) reduction have occurred naturally in the sediment. SEM/EDS analyses …


Heterogeneous Reduction Of Tc(Vii) By Fe(Ii) At The Solid–Water Interface, T. Peretyazhko, John M. Zachara, S.M. Heald, B.-H. Jeon, Ravi K. Kukkadapu, C. Liu, D. Moore, C.T. Resch Jan 2009

Heterogeneous Reduction Of Tc(Vii) By Fe(Ii) At The Solid–Water Interface, T. Peretyazhko, John M. Zachara, S.M. Heald, B.-H. Jeon, Ravi K. Kukkadapu, C. Liu, D. Moore, C.T. Resch

US Department of Energy Publications

Experiments were performed herein to investigate the rates and products of heterogeneous reduction of Tc(VII) by Fe(II) adsorbed to hematite and goethite, and by Fe(II) associated with a dithionite–citrate–bicarbonate (DCB) reduced natural phyllosilicate mixture [structural, ion-exchangeable, and edge-complexed Fe(II)] containing vermiculite, illite, and muscovite. The heterogeneous reduction of Tc(VII) by Fe(II) adsorbed to the Fe(III) oxides increased with increasing pH and was coincident with a second event of Fe2+(aq) adsorption. The reaction was almost instantaneous above pH 7. In contrast, the reduction rates of Tc(VII) by DCB-reduced phyllosilicates were not sensitive to pH or to added Fe2+ …


Mineralogical Transformations Controlling Acid Mine Drainage Chemistry, T. Peretyazhko, John M. Zachara, J.-F. Boily, Y. Xia, P.L. Gassman, B.W. Arey, W.D. Burgos Jan 2009

Mineralogical Transformations Controlling Acid Mine Drainage Chemistry, T. Peretyazhko, John M. Zachara, J.-F. Boily, Y. Xia, P.L. Gassman, B.W. Arey, W.D. Burgos

US Department of Energy Publications

The role of Fe(III) minerals in controlling acid mine drainage (AMD) chemistry was studied using samples from two AMD sites [Gum Boot (GB) and Fridays-2 (FR)] located in northern Pennsylvania. Chemical extractions, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were used to identify and characterize Fe(III) phases. The mineralogical analysis revealed schwertmannite and goethite as the principal Fe(III) phases in the sediments. Schwertmannite particles occurred as sub-micron sized spheroids. Their transformation into goethite occurred at the GB site where poorly-crystallized goethite rich in surface-bound sulfate was initially formed. In contrast, no schwertmannite transformation occurred …


The Roles Of Outer Membrane Cytochromes Of Shewanella And Geobacter In Extracellular Electron Transfer, Liang Shi, David J. Richardson, Zheming Wang, Sebastien Kerisit, Kevin Rosso, John M. Zachara, James K. Fredrickson Jan 2009

The Roles Of Outer Membrane Cytochromes Of Shewanella And Geobacter In Extracellular Electron Transfer, Liang Shi, David J. Richardson, Zheming Wang, Sebastien Kerisit, Kevin Rosso, John M. Zachara, James K. Fredrickson

US Department of Energy Publications

As key components of the electron transfer (ET) pathways used for dissimilatory reduction of solid iron [Fe(III)] (hydr)oxides, outer membrane multihaem c-type cytochromes MtrC and OmcA of Shewanella oneidensis MR-1 and OmcE and OmcS of Geobacter sulfurreducens mediate ET reactions extracellularly. Both MtrC and OmcA are at least partially exposed to the extracellular side of the outer membrane and their translocation across the outer membrane is mediated by bacterial type II secretion system. Purified MtrC and OmcA can bind Fe(III) oxides, such as haematite (α-Fe2O3), and directly transfer electrons to the haematite surface. Bindings of …


Electron Donor-Dependent Radionuclide Reduction And Nanoparticle Formation By Anaeromyxobacter Dehalogenans Strain 2cp-C, Matthew J. Marshall, Alice C. Dohnalkova, David Kennedy, Andrew Plymale, Sara Thomas, Frank Löffler, Robert Sanford, John M. Zachara, James K. Fredrickson, Alexander Beliaev Jan 2009

Electron Donor-Dependent Radionuclide Reduction And Nanoparticle Formation By Anaeromyxobacter Dehalogenans Strain 2cp-C, Matthew J. Marshall, Alice C. Dohnalkova, David Kennedy, Andrew Plymale, Sara Thomas, Frank Löffler, Robert Sanford, John M. Zachara, James K. Fredrickson, Alexander Beliaev

US Department of Energy Publications

Anaeromyxobacter dehalogenans strain 2CP-C reduces U(VI) and Tc(VII) to U(IV)O2(s) (uraninite) and Tc(IV)O2(S) respectively. Kinetic studies with resting cells revealed that U(VI) or Tc(VII) reduction rates using H2 as electron donor exceeded those observed in acetate-amended incubations. The reduction of U(VI) by A. dehalogenans 2CP-C resulted in extracellular accumulation of ~5 nm uraninite nanoparticles in association with a lectin-binding extracellular polymeric substance (EPS). The electron donor did not affect UO2(S) nanoparticle size or association with EPS, but the utilization of acetate as the source of reducing equivalents resulted in distinct UO2(S) nanoparticle aggregates that were ~50 …


Kinetics Of Uranium(Vi) Desorption From Contaminated Sediments: Effect Of Geochemical Conditions And Model Evaluation, Chongxuan Liu, Zhenqing Shi, John M. Zachara Jan 2009

Kinetics Of Uranium(Vi) Desorption From Contaminated Sediments: Effect Of Geochemical Conditions And Model Evaluation, Chongxuan Liu, Zhenqing Shi, John M. Zachara

US Department of Energy Publications

Stirred-flow cell experiments were performed to investigate the kinetics of uranyl [U(VI)] desorption from a contaminated sediment collected from the Hanford 300 Area at the U.S. Department of Energy Hanford Site, Washington. Three influent solutions of variable pH, Ca and carbonate concentrations that affected U(VI) aqueous and surface speciation were used under dynamic flow conditions to evaluate the effect of geochemical conditions on the rate of U(VI) desorption. The measured rate of U(VI) desorption varied with solution chemical composition that evolved as a result of thermodynamic and kinetic interactions between the solutions and sediment. The solution chemical composition that led …


Oxidative Dissolution Potential Of Biogenic And Abiogenic Tco2 In Subsurface Sediments, James K. Fredrickson, John M. Zachara, Andrew Plymale, Steve M. Heald, James Mckinley, David Kennedy, Chongxuan Liu, Ponnusamy Nachimuthu Jan 2009

Oxidative Dissolution Potential Of Biogenic And Abiogenic Tco2 In Subsurface Sediments, James K. Fredrickson, John M. Zachara, Andrew Plymale, Steve M. Heald, James Mckinley, David Kennedy, Chongxuan Liu, Ponnusamy Nachimuthu

US Department of Energy Publications

Technetium-99 (Tc) is an important fission product contaminant associated with sites of nuclear fuels reprocessing and geologic nuclear waste disposal. Tc is highly mobile in its most oxidized state [Tc(VII)O4] and less mobile in the reduced form [Tc(IV)O2nH2O]. Here we investigate the potential for oxidation of Tc(IV) that was heterogeneously reduced by reaction with biogenic Fe(II) in two sediments differing in mineralogy and aggregation state; unconsolidated Pliocene-age fluvial sediment from the upper Ringold (RG) Formation at the Hanford Site and a clay-rich saprolite from the Field Research Center (FRC) background site …


Newly Recognized Hosts For Uranium In The Hanford Site Vadose Zone, Joanne E. Stubbs, Linda A. Veblen, David C. Elbert, John M. Zachara, James A. Davis, David R. Veblen Jan 2009

Newly Recognized Hosts For Uranium In The Hanford Site Vadose Zone, Joanne E. Stubbs, Linda A. Veblen, David C. Elbert, John M. Zachara, James A. Davis, David R. Veblen

US Department of Energy Publications

Uranium contaminated sediments from the U.S. Department of Energy’s Hanford Site have been investigated using electron microscopy. Six classes of solid hosts for uranium were identified. Preliminary sediment characterization was carried out using optical petrography, and electron microprobe analysis (EMPA) was used to locate materials that host uranium. All of the hosts are fine-grained and intergrown with other materials at spatial scales smaller than the analytical volume of the electron microprobe. A focused ion beam (FIB) was used to prepare electron-transparent specimens of each host for the transmission electron microscope (TEM). The hosts were identified as: (1) metatorbernite [Cu(UO2 …


Characterization Of An Electron Conduit Between Bacteria And The Extracellular Environment, Robert Hartshorne, Catherine Reardon, Daniel Ross, Jochen Nuester, Thomas Clarke, Andrew Gates, Paul Mills, James K. Fredrickson, John M. Zachara, Liang Shi, Alexander Beliaev, Matthew Marshall, Ming Tien, Susan Brantley, Julea N. Butt, David J. Richardson Jan 2009

Characterization Of An Electron Conduit Between Bacteria And The Extracellular Environment, Robert Hartshorne, Catherine Reardon, Daniel Ross, Jochen Nuester, Thomas Clarke, Andrew Gates, Paul Mills, James K. Fredrickson, John M. Zachara, Liang Shi, Alexander Beliaev, Matthew Marshall, Ming Tien, Susan Brantley, Julea N. Butt, David J. Richardson

US Department of Energy Publications

A number of species of Gram-negative bacteria can use insoluble minerals of Fe(III) and Mn(IV) as extracellular respiratory electron acceptors. In some species of Shewanella, deca-heme electron transfer proteins lie at the extracellular face of the outer membrane (OM), where they can interact with insoluble substrates. To reduce extracellular substrates, these redox proteins must be charged by the inner membrane/periplasmic electron transfer system. Here, we present a spectro-potentiometric characterization of a trans-OM icosa-heme complex, MtrCAB, and demonstrate its capacity to move electrons across a lipid bilayer after incorporation into proteoliposomes. We also show that a stable MtrAB …


Photoionization Cross Sections For Ions Of The Cerium Isonuclear Sequence, M. Habibi, D. A. Esteves, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, C. Cisneros Jan 2009

Photoionization Cross Sections For Ions Of The Cerium Isonuclear Sequence, M. Habibi, D. A. Esteves, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, C. Cisneros

US Department of Energy Publications

Photoionization cross sections for Ceq+ (1 ≤ q ≤ 9) ions were measured in the 105–180 eV energy range of the 4d inner-shell giant resonance by merging a mass-to-charge-ratio-selected ion beam with a beam of monochromatized synchrotron radiation. The Cowan atomic structure code was used as an aid to interpret the experimental data. Four Rydberg series for 4d→nf (n ≥ 4) and 4d→np (n ≥ 6) autoionizing excitations were assigned using the quantum-defect theory in the Ce3+ photoionization cross section. The experimental data show the collapse of the nf wave functions (n ≥ 4) with …


Fullerene-Encapsulated Atoms In The Light Of Synchrotron Radiation, A. M. Müller, S. Schippers, D. Esteves, M. Habibi, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, L. Dunsch Jan 2009

Fullerene-Encapsulated Atoms In The Light Of Synchrotron Radiation, A. M. Müller, S. Schippers, D. Esteves, M. Habibi, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, L. Dunsch

US Department of Energy Publications

Mass-selected beams of endohedral fullerene Ce@C+82 ions, of atomic Ceq+ ions (q=2,3,4), and of empty fullerene-cage C+82 ions were employed to study photoionization of fullerene-encapsulated and free cerium atoms. The Ce 4d inner-shell contributions to single and double ionization of the endohedral Ce@C+82 fullerene have been extracted from the data and compared with expectations based on theory and the experiments with atomic Ce ions. Dramatic reduction and redistribution of the ionization contributions to Ce 4d photoabsorption is observed. More than half of the Ce 4d oscillator strength is apparently diverted to …


Doe Climate Change Research Program: Strategic Plan Jan 2009

Doe Climate Change Research Program: Strategic Plan

US Department of Energy Publications

Advance the forefront of climate change research to provide the nation with the scientific knowledge it needs about the effects of greenhouse gas emissions on Earth's climate and biosphere to support effective energy and environmental decision making.