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Articles 5581 - 5610 of 11222

Full-Text Articles in Engineering

Inspector’S Manual For Mechanically Stabilized Earth Walls, Wayne Jensen Ph.D. Jan 2009

Inspector’S Manual For Mechanically Stabilized Earth Walls, Wayne Jensen Ph.D.

Mid-America Transportation Center: Final Reports and Technical Briefs

The scope of the project is to develop a condition rating system, creation of an inspector's manual to reference during inspection or address any training for inspectors at the district level. The research project will develop a MSE wall condition rating system and incorporate this system into the database being developed and create training and reference manuals


Investigation And Mitigation Of Driver Confusion At Modern Roundabouts, Aemal Khattak, Ram Bishu, Karen Schurr, Gregory Mcknight Jan 2009

Investigation And Mitigation Of Driver Confusion At Modern Roundabouts, Aemal Khattak, Ram Bishu, Karen Schurr, Gregory Mcknight

Mid-America Transportation Center: Final Reports and Technical Briefs

This research deals with two related issues: investigation and mitigation of roundabout elements that lead to driver confusion, and development of a flexible criteria matrix by which the Nebraska Department of Roads (NDOR) can evaluate arterial intersections to identify good candidates for conversion to roundabouts. The use of modern roundabouts along arterial roadways is relatively new in Nebraska. The first urban arterial roundabout was opened to traffic in June of 2002 at the intersection of 33rd and Sheridan Blvd in the City of Lincoln. Citizens and some professionals were somewhat skeptical of the capability of this roundabout to improve traffic …


Acuta Enews January 2009, Vol 38, No. 1 Jan 2009

Acuta Enews January 2009, Vol 38, No. 1

ACUTA Newsletters

ln This lssue

Board approves slate of nominees for 2009-10

From ACUTA headquarters: looking back and looking ahead.......... Jeri Semer, CAE, Exec. Dir.

Be moderator or monitor at the annual conference

Tech talk: a clean slate, and a clean network, for the new year......... Kevin Tanzillo, Dux PR

DC update.......... Dave Ostrom, Washington State University (retired)

FCC summit on pandemic preparedness............. Ed Quinn, The Ohio State University

Board Report, December............. Riny Ledgerwood, San Diego State University

Special Deals and discounts from ACUTA corporate members

Thanks to journal advertisers for 2008

Info Links............. Randy Hayes, Univ. of Northern Iowa

Welcome New …


Annealing Effects On The Optical Properties Of Semiconducting Boron Carbide, R. B. Billa, Tino Hofmann, Mathias Schubert, Brian W. Robertson Jan 2009

Annealing Effects On The Optical Properties Of Semiconducting Boron Carbide, R. B. Billa, Tino Hofmann, Mathias Schubert, Brian W. Robertson

Nebraska Center for Materials and Nanoscience: Faculty Publications

Infrared vibrations of as-deposited and annealed semiconducting boron carbide thin films were investigated by midinfrared spectroscopic ellipsometry. The strong boron-hydrogen resonance at ~2560 cm−1 in as-deposited films reveals considerable hydrogen incorporation during plasma-enhanced chemical vapor deposition. Extended annealing at 600 °C caused significant reduction in film thickness, substantial reduction of boron-hydrogen bond resonance absorption, and development of distinct blue-shifted boron-carbon and icosahedral vibration mode resonances. Our findings suggest that annealing results in substantial loss of hydrogen and in development of icosahedral structure, accompanied by strain relaxation and densification.


Dynamic Evaluation Of New York State’S Aluminum Pedestrian Signal Pole System, Scott K. Rosenbaugh, Ronald K. Faller, Karla A. Lechtenberg, Robert W. Bielenberg, Dean L. Sicking, John D. Reid Jan 2009

Dynamic Evaluation Of New York State’S Aluminum Pedestrian Signal Pole System, Scott K. Rosenbaugh, Ronald K. Faller, Karla A. Lechtenberg, Robert W. Bielenberg, Dean L. Sicking, John D. Reid

Mid-America Transportation Center: Final Reports and Technical Briefs

The New York State Department of Transportation (NYSDOT) mounts pedestrian “hand/man” signals to aluminum

poles and uses frangible transformer bases to allow the system to break away. However, engineers at NYSDOT believed that the material properties of the aluminum poles themselves would allow the pedestrian signal poles to break away without the use of transformer bases. Elimination of the frangible transformer base would result in significant savings.

An aluminum pedestrian signal pole system was erected at the Valmont testing facility and tested with the Valmont- MwRSF/UNL pendulum with crushable nose in accordance with NCHRP Report No. 350 test designation no. …


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

United States 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.


United States Air Force Posture Statement 2009, U.S. Air Force Jan 2009

United States Air Force Posture Statement 2009, U.S. Air Force

United States Air Force: Publications

Today, the United States faces a spectrum of challenges to our national security and global interests. As an integral member of the Joint team, America’s Air Force provides the critical capabilities of Global Vigilance, Global Reach, and Global Power. The United States Air Force is 'All In" today’s Joint fight. At the same time, our investments in new capabilities will ensure we are ready for tomorrow’s challenges. The mission of the United States Air Force is to "fly, fight, and win…in air, space and cyberspace"—as an integral member of the Joint …


Comparison Of The Trivalent Live Attenuated Vs. Inactivated Influenza Vaccines Among U.S. Military Service Members, Angelia A. Eick, Zhong Wang, Hayley Hughes, Stephen M. Ford, Steven K. Tobler Jan 2009

Comparison Of The Trivalent Live Attenuated Vs. Inactivated Influenza Vaccines Among U.S. Military Service Members, Angelia A. Eick, Zhong Wang, Hayley Hughes, Stephen M. Ford, Steven K. Tobler

United States Army: Publications

Limited effectiveness data are available comparing live attenuated influenza vaccine (LAIV) to inactivated influenza vaccine (TIV) among adults. To compare the incidence of influenza-like illness following immunization of adults with LAIV vs. TIV,we conducted a retrospective cohort analysis of active component U.S. military personnel for the 2005–2006 and 2006–2007 influenza seasons. Recruits experienced a much higher burden of disease compared to non-recruits, with crude incidence rates of influenza-like illness 2–16 times higher than non-recruits depending on the season and cohort. For both seasons, a slightly greater protection from influenza-like illness was found for non-recruits who received TIV compared to LAIV …


Unimolecular Decomposition Of 5-Aminotetrazole And Its Tautomer 5-Iminotetrazole: New Insight From Isopotential Searching, Kristian W. Paul, Margaret M. Hurley, Karl K. Irikura Jan 2009

Unimolecular Decomposition Of 5-Aminotetrazole And Its Tautomer 5-Iminotetrazole: New Insight From Isopotential Searching, Kristian W. Paul, Margaret M. Hurley, Karl K. Irikura

United States Army: Publications

Aminotetrazole compounds have become attractive ingredients in gas generating compositions, solid rocket propellants, and green pyrotechnics. Therefore, a fundamental understanding of their thermal decomposition mechanisms and thermodynamics is of great interest. In this study, the specular reflection isopotential searching method was used to investigate the unimolecular decomposition mechanisms of 5-iminotetrazole (5-ITZ), 1H-5-aminotetrazole (1H-5-ATZ), and 2H-5-aminotetrazole (2H-5-ATZ). Subsequent thermochemical analysis of the unimolecular decomposition pathways was performed at the CCSD(T)/aug-cc-pVTZ//B3LYP/6- 311++G(3df,3pd) level of theory. Based upon the relative reaction barriers predicted in this study, the initial gaseous products of 5-ITZ unimolecular decomposition are HN3 and NH2CN (calculated activation …


Three Examples Where The Specific Surface Area Of Snow Increased Over Time, F. Domine, A. S. Taillandier, A. Cabanes, T. A. Douglas, M. Sturm Jan 2009

Three Examples Where The Specific Surface Area Of Snow Increased Over Time, F. Domine, A. S. Taillandier, A. Cabanes, T. A. Douglas, M. Sturm

United States Army: Publications

Snow on the ground impacts climate through its high albedo and affects atmospheric composition through its ability to adsorb chemical compounds. The quantification of these effects requires the knowledge of the specific surface area (SSA) of snow and its rate of change. All relevant studies indicate that snow SSA decreases over time. Here, we report for the first time three cases where the SSA of snow increased over time. These are (1) the transformation of a melt-freeze crust into depth hoar, producing an increase in SSA from 3.4 to 8.8m2 kg−1. (2) The mobilization of surface snow …


Three Examples Where The Specific Surface Area Of Snow Increased Over Time, F. Domine, A.-S. Taillandier, A. Cabanes, T. A. Douglas, M. Sturm Jan 2009

Three Examples Where The Specific Surface Area Of Snow Increased Over Time, F. Domine, A.-S. Taillandier, A. Cabanes, T. A. Douglas, M. Sturm

United States Army: Publications

Snow on the ground impacts climate through its high albedo and affects atmospheric composition through its ability to adsorb chemical compounds. The quantification of these effects requires the knowledge of the specific surface area (SSA) of snow and its rate of change. All relevant studies indicate that snow SSA decreases over time. Here, we report for the first time three cases where the SSA of snow increased over time. These are (1) the transformation of a melt-freeze crust into depth hoar, producing an increase in SSA from 3.4 to 8.8m2 kg−1. (2) The mobilization of surface snow …


Co-Op E3 Cockshutt 30 Restoration, Tractor Museum Jan 2009

Co-Op E3 Cockshutt 30 Restoration, Tractor Museum

Tractor Maintenance, Repair, and Restoration

Larsen Tractor Museum 2009 Restoration Project


Biological Opinion On The Operation Of The Missouri River Main Stem System, Operation And Maintenance Of The Missouri River Bank Stabilization And Navigation Project, And Operation Of The Kansas River Reservoir System Jan 2009

Biological Opinion On The Operation Of The Missouri River Main Stem System, Operation And Maintenance Of The Missouri River Bank Stabilization And Navigation Project, And Operation Of The Kansas River Reservoir System

United States Army Corps of Engineers, Omaha District

The U.S. Army Corps of Engineers (Corps) prepared this Annual Report for interested parties in accordance with reporting recommendations of the Biological Opinion on the Operation of the Missouri River Main Stem System (System), Operation and Maintenance of the Missouri River Bank Stabilization and Navigation Project and Operation of the Kansas River Reservoir System, prepared by the U.S. Fish and Wildlife Service (USFWS), dated November 30, 2000, and the Amendment thereto, dated December 16, 2003 (BiOp). This annual report also documents the Corps’ activities implemented under the Missouri River Bank Stabilization and Navigation Fish and Wildlife Mitigation Project, Iowa, Nebraska, …


Missouri River Recovery Program: Flood Risk Management Jan 2009

Missouri River Recovery Program: Flood Risk Management

United States Army Corps of Engineers, Omaha District

One of the U.S. Army Corps of Engineers’ main responsibilities in managing the Missouri River is protecting property from flood damage. Historically, the dynamic river changed course during the spring and summer months, flooding some areas and eroding banks in other areas. Today, approximately 1.4 million acres of farmland and nearly $18 billion dollars of residential and other property are subject to flooding along the Missouri River. Agricultural lands, residential areas, business districts and navigation benefit from flood risk management measures provided by the Corps through the system of reservoirs on the Missouri River.


Missouri River Recovery Program: Water Supply And Water Quality Jan 2009

Missouri River Recovery Program: Water Supply And Water Quality

United States Army Corps of Engineers, Omaha District

The Army Corps of Engineers (Corps) operates a system of six dams and reservoirs on the Missouri River to serve the multiple purposes authorized by Congress in the Flood Control Act of 1944. In addition to operating the system for flood control, navigation, hydropower, recreation, and fish and wildlife, the Corps is also authorized to use the system for irrigation, water supply and water quality. This fact sheet will discuss the Corps efforts regarding these three authorized project purposes.


Missouri River Recovery - Integrated Science Program Jan 2009

Missouri River Recovery - Integrated Science Program

United States Army Corps of Engineers, Omaha District

Book List

System-wide Status Reports, Guidance Documents & Standard Operating Plans

Pallid Sturgeon

Least Tern and Piping Plover

Flow Modifications

Adaptive Management

Cottonwoods


Nebraska Summary: S695 Agco Rt155a, Nebraska Tractor Test Lab Jan 2009

Nebraska Summary: S695 Agco Rt155a, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …


Tomato Bushy Stunt Virus (Tbsv), A Versatile Platform For Polyvalent Display Of Antigenic Epitopes And Vaccine Design, Shantanu Kumar, Wendy Ochoa, Pratik Singh, Catherine Hsu, Anette Schneemann, Marianne Manchester, Mark Olson, Vijay Reddy Jan 2009

Tomato Bushy Stunt Virus (Tbsv), A Versatile Platform For Polyvalent Display Of Antigenic Epitopes And Vaccine Design, Shantanu Kumar, Wendy Ochoa, Pratik Singh, Catherine Hsu, Anette Schneemann, Marianne Manchester, Mark Olson, Vijay Reddy

United States Army: Publications

Viruses-like particles (VLPs) are frequently being used as platforms for polyvalent display of foreign epitopes of interest on their capsid surface to improve their presentation enhancing the antigenicity and host immune response. In the present study, we used the VLPs of Tomato bushy stunt virus (TBSV), an icosahedral plant virus, as a platform to display 180 copies of 16 amino acid epitopes of ricin toxin fused to the C-terminal end of a modified TBSV capsid protein (NΔ52). Expression of the chimeric recombinant protein in insect cells resulted in spontaneous assembly of VLPs displaying the ricin epitope. Cryo-electron microscopy and image …


Simulated Rainfall-Driven Dissolution Of Tnt, Tritonal, Comp B And Octol Particles, Susan Taylor, James H. Lever, Jennifer Fadden, Nancy Perron, Bonnie Packer Jan 2009

Simulated Rainfall-Driven Dissolution Of Tnt, Tritonal, Comp B And Octol Particles, Susan Taylor, James H. Lever, Jennifer Fadden, Nancy Perron, Bonnie Packer

United States Army: Publications

Live-fire military training can deposit millimeter-sized particles of high explosives (HE) on surface soils when rounds do not explode as intended. Rainfall-driven dissolution of the particles then begins a process whereby aqueous HE solutions can enter the soil and groundwater as contaminants. We dripped water onto individual particles of TNT, Tritonal, Comp B and Octol to simulate how surface-deposited HE particles might dissolve under the action of rainfall and to use the data to verify a model that predicts HE dissolution as a function of particle size, particle composition and rainfall rate. Particle masses ranged from 1.1 to 17 mg …


Complementary And Alternative Medicine For The Allergist-Immunologist: Where Do I Start?, Renata J. M. Engler, Catherine M. With, Philip J. Gregory, Jeff M. Jellin Jan 2009

Complementary And Alternative Medicine For The Allergist-Immunologist: Where Do I Start?, Renata J. M. Engler, Catherine M. With, Philip J. Gregory, Jeff M. Jellin

United States Army: Publications

Complementary and alternative medicine (CAM) therapies present a growing information management challenge for physicians because nearly 40% of their patients may be using and another 50% may be considering use of CAM as part of their health care regimen. The National Health Statistics Reports for 2007 described the most commonly used nonvitamin, nonmineral therapy as natural products (eg, herbals at 17.7%). More than5% of children under the age of 18 years used CAM for allergic conditions including asthma. The amount and quality of information available and concerns about liability risk represent a challenge for most physicians. This review focuses on …


First Results From Radar Profiles Collected Along The Us-Itase Traverse From Taylor Dome To South Pole (2006–2008), Brian C. Welch, Robert W. Jacobel, Steven A. Arcone Jan 2009

First Results From Radar Profiles Collected Along The Us-Itase Traverse From Taylor Dome To South Pole (2006–2008), Brian C. Welch, Robert W. Jacobel, Steven A. Arcone

United States Army: Publications

The 2006/07 and 2007/08 US-ITASE traverses from Taylor Dome to South Pole in East Antarctica provided opportunities to survey the subglacial and englacial environments using 3MHz and 200MHz radar. We present first results of these new ground-based radar data. A prominent basal deformation layer indicates different ice-flow regimes for the northern and southern halves of the Byrd Glacier drainage. Buried dune stratigraphy that appears to be related to the megadunes towards the west occurs at depths of up to 1500 m. At least two new water-filled subglacial lakes were discovered, while two recently drained lakes identified from repeat ICESat surface …


Selecting And Conserving Lands For Biodiversity: The Role Of Remote Sensing, John Wiens, Robert Sutter, Mark Anderson, Jon Blanchard, Analie Barnett, Naikoa Aguilar-Amuchastegui, Chadwick Avery, Stephen Laine Jan 2009

Selecting And Conserving Lands For Biodiversity: The Role Of Remote Sensing, John Wiens, Robert Sutter, Mark Anderson, Jon Blanchard, Analie Barnett, Naikoa Aguilar-Amuchastegui, Chadwick Avery, Stephen Laine

United States Air Force: Publications

A major focus of conservation is on protecting areas to ensure the persistence of biological diversity. Because such areas may be large, not easily accessible, subject to change, and sensitive to the surrounding landscape, remote sensing can be a valuable tool in establishing and managing protected areas. We describe three case studies to illustrate how remote sensing can contribute to setting priorities for conservation actions, monitoring the status of conservation targets, and evaluating the effectiveness of conservation strategies. In the Connecticut River watershed, remote sensing has been used to assess flood regimes and identify key areas of floodplain forests and …


Surface-Initiated Titanium-Mediated Coordination Polymerization From Catalyst-Functionalized Single And Multiwalled Carbon Nanotubes, Dimitrios Priftis, Nikolaos Petzetakis, Georgios Sakellariou, Marinos Pitsikalis, Durairaj Baskaran, Jimmy W. Mays, Nikos Hadjichristidis Jan 2009

Surface-Initiated Titanium-Mediated Coordination Polymerization From Catalyst-Functionalized Single And Multiwalled Carbon Nanotubes, Dimitrios Priftis, Nikolaos Petzetakis, Georgios Sakellariou, Marinos Pitsikalis, Durairaj Baskaran, Jimmy W. Mays, Nikos Hadjichristidis

United States Department of Energy: Publications

Single (SWNTs) and multiwalled (MWNTs) carbon nanotubes were functionalized with a titanium alkoxide catalyst through a Diels-Alder cycloaddition reaction. The catalyst-functionalized carbon nanotubes (CNTs) were used for the surface initiated titanium-mediated coordination polymerizations of L-lactide (L-LA), ε-caprolactone (ε-CL) and n-hexyl isocyanate (HIC) employing the “grafting from” technique. 1H NMR, IR and Raman spectra showed that the precursor catalyst was successfully synthesized and covalently attached on the CNTs surface. Thermogravimetric analysis (TGA) revealed that the grafted poly(L-lactide) (PLLA) content could be controlled with time. The final polymer-grafted CNTs were readily dissolved in organic solvents as compared to the insoluble pristine …


Morphology And Deformation Mechanisms And Tensile Properties Of Tetrafunctional Multigraft Copolymers, Yongxin Duan, Mahendra Thunga, Ralf Schlegel, Konrad Schneider, Erik Rettler, Roland Weidisch, Heinz W. Siesler, Manfred Stamm, Jimmy W. Mays, Nikos Hadjichristidis Jan 2009

Morphology And Deformation Mechanisms And Tensile Properties Of Tetrafunctional Multigraft Copolymers, Yongxin Duan, Mahendra Thunga, Ralf Schlegel, Konrad Schneider, Erik Rettler, Roland Weidisch, Heinz W. Siesler, Manfred Stamm, Jimmy W. Mays, Nikos Hadjichristidis

United States Department of Energy: Publications

Morphology and deformation mechanisms and tensile properties of tetrafunctional multigraft (MG) polystrene-g-polyisoprene (PS-g-PI) copolymers were investigated dependent on PS volume fraction and number of branch points. The combination of various methods such as TEM, real time synchrotron SAXS, rheo-optical FTIR, and tensile tests provides comprehensive information at different dimension levels.TEMand SAXS studies revealed that the number of branch points has no obvious influence on the microphase-separated morphology of tetrafunction MG copolymers with 16 wt % PS. But for tetrafunctional MG copolymers with 25 wt % PS, the size and integrity of PS microdomains decrease with increasing number of branch point. …


High-Pressure Micellar Solutions Of Polystyrene-Block-Polybutadiene And Polystyrene-Block-Polyisoprene In Propane Exhibit Cloud-Pressure Reduction And Distinct Micellization End Points, Winoto Winoto, Sugata P. Tan, Youqing Shen, Maciej Radosz, Kunlun Hong, Jimmy W. Mays Jan 2009

High-Pressure Micellar Solutions Of Polystyrene-Block-Polybutadiene And Polystyrene-Block-Polyisoprene In Propane Exhibit Cloud-Pressure Reduction And Distinct Micellization End Points, Winoto Winoto, Sugata P. Tan, Youqing Shen, Maciej Radosz, Kunlun Hong, Jimmy W. Mays

United States Department of Energy: Publications

Micellar solutions of polystyrene-block-polybutadiene and polystyrene-block-polyisoprene in propane are found to exhibit significantly lower cloud pressures than the corresponding hypothetical nonmicellar solutions. Such a cloud-pressure reduction indicates the extent to which micelle formation enhances the apparent diblock solubility in near-critical and hence compressible propane. Concentration-dependent pressure-temperature points beyond which no micelles can be formed, referred to as the micellization end points, are found to depend on the block type, size, and ratio. The cloud-pressure reduction and the micellization end point measured for styrene-diene diblocks in propane should be characteristic of all amphiphilic diblock copolymer solutions that form micelles in compressible …


Feasibility, Economics, And Environmental Impact Of Producing 90 Billion Gallons Of Ethanol Per Year By 2030, Todd West, Katherine Dunphy-Guzman, Amy Sun, Len Malczunski, David Reichmuth, Richard Larson, James Ellison, Robert Taylor, Vincent Tidwell, Lennie Klebanoff, Patricia Hough, Andrew Lutz, Christopher Shaddix, Norman Brinkman, Candace Wheeler, David O'Toole Jan 2009

Feasibility, Economics, And Environmental Impact Of Producing 90 Billion Gallons Of Ethanol Per Year By 2030, Todd West, Katherine Dunphy-Guzman, Amy Sun, Len Malczunski, David Reichmuth, Richard Larson, James Ellison, Robert Taylor, Vincent Tidwell, Lennie Klebanoff, Patricia Hough, Andrew Lutz, Christopher Shaddix, Norman Brinkman, Candace Wheeler, David O'Toole

United States Department of Energy: Publications

This paper addresses a national interest in investigating the potential of displacing a large fraction of U.S. gasoline use by 2030 with ethanol. This study assesses the feasibility, implications, limitations, and enablers of producing 90 billion gallons ethanol per year by 2030. We developed a dynamic supply chain model, the Biofuels Deployment Model (BDM), and conducted sensitivity analyses to determine the parameters that most affect the feasibility, cost-competitiveness, and greenhouse gas impact of large-scale ethanol production. Though we found no theoretical barriers to achieving the stated goal, we identified a number of practical obstacles that need to be addressed. In …


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

United States 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

United States 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 …


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

United States 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) …


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

United States 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 …