Open Access. Powered by Scholars. Published by Universities.®

Bioresource and Agricultural Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

United States Department of Energy: Publications

Articles 181 - 210 of 355

Full-Text Articles in Bioresource and Agricultural Engineering

Small Wind Electric Systems: A Nebraska Consumer’S Guide Jan 2007

Small Wind Electric Systems: A Nebraska Consumer’S Guide

United States Department of Energy: Publications

Can I use wind energy to power my home? This question is being asked across the country as more people look for affordable and reliable sources of electricity. Small wind electric systems can make a significant contribution to our nation’s energy needs. Although wind turbines large enough to provide a significant portion of the electricity needed by the average U.S. home generally require one acre of property or more, approximately 21 million U.S. homes are built on one-acre and larger sites, and 24% of the U.S. population lives in rural areas.

A small wind electric system will work for you …

Go to article

Geochemical Controls On Contaminant Uranium In Vadose Hanford Formation Sediments At The 200 Area And 300 Area, Hanford Site, Washington, James Mckinley, John M. Zachara, Jiamin Wan, David Mccready, Steven M. Heald Jan 2007

Geochemical Controls On Contaminant Uranium In Vadose Hanford Formation Sediments At The 200 Area And 300 Area, Hanford Site, Washington, James Mckinley, John M. Zachara, Jiamin Wan, David Mccready, Steven M. Heald

United States Department of Energy: Publications

Long-term historic spills of uranium at the 300 Area fuel fabrication site (58,000 kg of disposed uranium over 32 yr) and at the 200 East Area BX tank farm (7000 kg of spilled uranium in one event), both within the Hanford formation in the Hanford Site, Washington State, were investigated by subsurface sampling and subsequent microscale investigations of excavated samples. The 200 Area sediments contained uranyl silicate mineralization (sodium boltwoodite) in restrictive microfractures in granitic clasts, in the vadose zone over a narrow range in depth. Well logging and column experiments indicated that tank wastes migrated deeper than observed in …

Go to article

Hanford Site Vadose Zone Studies: An Overview, G. W. Gee, M. Oostrom, M. D. Freshley, M. L. Rockhold, John M. Zachara Jan 2007

Hanford Site Vadose Zone Studies: An Overview, G. W. Gee, M. Oostrom, M. D. Freshley, M. L. Rockhold, John M. Zachara

United States Department of Energy: Publications

Large quantities of radioactive and chemical wastes resulting from Pu production for nuclear weapons are located in the vadose zone at the USDOE’s Hanford Site, north of Richland, WA. The vadose zone here is characterized by often highly stratified glacial-fluvial sediments that give rise to complex subsurface-flow paths that contribute to uncertainty of contaminant fate and transport. Research efforts have focused on answering questions of contaminant transport from the viewpoint of geologic, biologic, geochemical, and hydrologic controls. This special section highlights key research topics concerning vadose zone problems at the Hanford Site. Research indicates that some of the contaminant species …

Go to article

Development Of A High Average Current Polarized Electron Source With Long Cathode Operational Lifetime, C. K. Sinclair, P. Adderley, B. M. Dunham, J. C. Hansknecht, P. Hartmann, M. Poelker, J. S. Price, P. M. Rutt, W. J. Schneider, M. Steigerwald Jan 2007

Development Of A High Average Current Polarized Electron Source With Long Cathode Operational Lifetime, C. K. Sinclair, P. Adderley, B. M. Dunham, J. C. Hansknecht, P. Hartmann, M. Poelker, J. S. Price, P. M. Rutt, W. J. Schneider, M. Steigerwald

United States Department of Energy: Publications

Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory) require highly polarized electron beams, often at high average current. Spinpolarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have …

Go to article

Photoionization And Electron-Impact Ionization Of Ar5+, Jing Cheng Wang, M. Lu, D. A. Esteves, M. Habibi, G. Alna’Washi, R. A. Phaneuf, A. L. D. Kilcoyne Jan 2007

Photoionization And Electron-Impact Ionization Of Ar5+, Jing Cheng Wang, M. Lu, D. A. Esteves, M. Habibi, G. Alna’Washi, R. A. Phaneuf, A. L. D. Kilcoyne

United States Department of Energy: Publications

Absolute cross sections for photoionization and electron-impact ionization of Ar5+ have been measured using two different interacting-beams setups. The spectra consist of measurements of the yield of products due to single ionization as a function of electron or photon energy. In addition, absolute photoionization and electron-impact ionization cross sections were measured to normalize the measured Ar6+ product-ion yield spectra. In the energy range from 90 to 111 eV, both electron-impact ionization and photoionization of Ar5+ are dominated by indirect 3s subshell excitation-autoionization. In the energy range from 270 to 285 eV, resonances due to 2p …

Go to article

Convergence Of Peridynamics To Classical Elasticity Theory, S. A. Silling, R. B. Lehoucq Jan 2007

Convergence Of Peridynamics To Classical Elasticity Theory, S. A. Silling, R. B. Lehoucq

United States Department of Energy: Publications

The peridynamic model of solid mechanics is a nonlocal theory containing a length scale. It is based on direct interactions between points in a continuum separated from each other by a finite distance. The maximum interaction distance provides a length scale for the material model. This paper addresses the question of whether the peridynamic model for an elastic material reproduces the classical local model as this length scale goes to zero. We show that if the motion, constitutive model, and any nonhomogeneities are sufficiently smooth, then the peridynamic stress tensor converges in this limit to a Piola-Kirchhoff stress tensor that …

Go to article

Uranium(Vi) Release From Contaminated Vadose Zone Sediments: Estimation Of Potential Contributions From Dissolution And Desorption, Deborah L. Bond, James A. Davis, John M. Zachara Jan 2007

Uranium(Vi) Release From Contaminated Vadose Zone Sediments: Estimation Of Potential Contributions From Dissolution And Desorption, Deborah L. Bond, James A. Davis, John M. Zachara

United States Department of Energy: Publications

A key difficulty in developing accurate, science-based conceptual models for remediation of contaminated field sites is the proper accounting of multiple coupled geochemical and hydrologic processes. An example of such a difficulty is the separation of desorption and dissolution processes in releasing contaminants from sediments to groundwaters; very few studies are found in the literature that attempt to quantify contaminant release by these two processes. In this study, the results from several extraction techniques, isotopic exchange experiments, and published spectroscopic studies were combined to estimate the contributions of desorption and dissolution to U(VI) release from contaminated sediments collected from the …

Go to article

Kinetics Of Reductive Dissolution Of Hematite By Bioreduced Anthraquinone-2,6-Disulfonate, Chongxuan Liu, John M. Zachara, Nancy Foster, Janae Strickland Jan 2007

Kinetics Of Reductive Dissolution Of Hematite By Bioreduced Anthraquinone-2,6-Disulfonate, Chongxuan Liu, John M. Zachara, Nancy Foster, Janae Strickland

United States Department of Energy: Publications

The reductive dissolution of hematite (α-Fe2O3) was investigated in a flow-through system using AH2DS, a reduced form of anthraquinone-2,6-disulfonate (AQDS), which is often used as a model electron shuttling compound in studies of dissimilatory microbial reduction of iron oxides. Influent flow rate, pH, and Fe(II) and phosphate concentrations were varied to investigate the redox kinetics in a flow-through reactor. The hematite reduction rates decreased with increasing pH from 4.5 to 7.6 and decreased with decreasing flow rate. The rates also decreased with increasing influent concentration of Fe(II) or phosphate that formed surface complexes at the experimental …

Go to article

Respiration Of Metal (Hydr)Oxides By Shewanella And Geobacter: A Key Role For Multihaem C-Type Cytochromes, Liang Shi, Thomas C. Squier, John M. Zachara, James K. Fredrickson Jan 2007

Respiration Of Metal (Hydr)Oxides By Shewanella And Geobacter: A Key Role For Multihaem C-Type Cytochromes, Liang Shi, Thomas C. Squier, John M. Zachara, James K. Fredrickson

United States Department of Energy: Publications

Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal …

Go to article

Biomass Energy Data Book, Volume 1, Lynn Wright, Bob Boundy, Bob Perlack, Stacy Davis, Bo Saulsbury Sep 2006

Biomass Energy Data Book, Volume 1, Lynn Wright, Bob Boundy, Bob Perlack, Stacy Davis, Bo Saulsbury

United States Department of Energy: Publications

The Biomass Energy Data Book is a statistical compendium prepared and published by Oak Ridge National Laboratory (ORNL) under contract with the Office of Planning, Budget, and Analysis in the Energy Efficiency and Renewable Energy (EERE) program of the Department of Energy (DOE). Designed for use as a convenient reference, the book represents an assembly and display of statistics and information that characterize the biomass industry, from the production of biomass feedstocks to their end use.
This is the first edition of the Biomass Energy Data Book and is currently only available online in electronic format. There are five main …

Go to article

The Doe Consortium For Research On Enhancing Carbon Sequestration In Terrestial Ecosystems: Fy 2007-2011 Five Year Science Plan, U.S. Department Of Energy Sep 2006

The Doe Consortium For Research On Enhancing Carbon Sequestration In Terrestial Ecosystems: Fy 2007-2011 Five Year Science Plan, U.S. Department Of Energy

United States Department of Energy: Publications

The DOE Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE) conducts multi-scale research to acquire basic knowledge for underpinning the implementation of soil carbon (C) sequestration in an environmentally acceptable and economically feasible manner. Research is based on the premise that identifying and understanding the basic mechanisms controlling sequestration across managed and unmanaged ecosystems are fundamental to developing approaches for enhancing C capture and long-term storage. The goal is to discover and characterize links among physical, chemical, and biological processes controlling soil C dynamics and storage at a mechanistic level to facilitate the enhancement of C storage …

Go to article

Microscopic Reactive Diffusion Of Uranium In The Contaminated Sediments At Hanford, United States, Chongxuan Liu, John M. Zachara, Wassana Yantasee, Paul D. Majors, James Mckinley Jan 2006

Microscopic Reactive Diffusion Of Uranium In The Contaminated Sediments At Hanford, United States, Chongxuan Liu, John M. Zachara, Wassana Yantasee, Paul D. Majors, James Mckinley

United States Department of Energy: Publications

Microscopic and spectroscopic analyses of uranium-contaminated sediments from select locations at the U.S. Department of Energy (DOE) Hanford site have revealed that sorbed uranium (U) often exists as uranyl precipitates associated with intragrain fractures of granitic clasts. The release of U to contacting fluids appears to be controlled by intragrain ion diffusion coupled with the dissolution kinetics of the precipitates that exist in the form of Na-boltwoodite. Here we present a coupled microscopic reactive diffusion model for the contaminated sediment on the basis of experimental measurements of intragrain diffusivity in the granitic lithic fragments and the dissolution kinetics of synthetic …

Go to article

Morphology And Tensile Properties Of Multigraft Copolymers With Regularly Spaced Tri-, Tetra-, And Hexafunctional Junction Points, Yuqing Zhu, Engin Burgaz, Samuel P. Gido, Ulrike Staudinger, Roland Weidisch, David Uhrig, Jimmy W. Mays Jan 2006

Morphology And Tensile Properties Of Multigraft Copolymers With Regularly Spaced Tri-, Tetra-, And Hexafunctional Junction Points, Yuqing Zhu, Engin Burgaz, Samuel P. Gido, Ulrike Staudinger, Roland Weidisch, David Uhrig, Jimmy W. Mays

United States Department of Energy: Publications

The effect of chain architecture on the morphological and tensile properties of series of multigraft copolymers, with regularly spaced tri-, tetra-, and hexafunctional junction points, was investigated using transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and tensile testing. The materials were synthesized by coupling difunctional polyisoprene (PI) spacers and living polystyrene (PS) branches, made by anionic polymerization, with chlorosilanes of different functionalities. Since the coupling process is a step-growth polymerization, yielding polydisperse products, fractionation was utilized to separate each material into three fractions (high, middle, and low molecular weight), each of low polydispersity. All three fractions have the same …

Go to article

Well-Defined Poly(4-Vinylbenzocyclobutene): Synthesis By Living Anionic Polymerization And Characterization, Georgios Sakellariou, Durairaj Baskaran, Nikos Hadjichristidis, Jimmy W. Mays Jan 2006

Well-Defined Poly(4-Vinylbenzocyclobutene): Synthesis By Living Anionic Polymerization And Characterization, Georgios Sakellariou, Durairaj Baskaran, Nikos Hadjichristidis, Jimmy W. Mays

United States Department of Energy: Publications

Living anionic polymerization of 4-vinylbenzocylobutene was performed in benzene at room temperature using sec-butyllithium as the initiator. Results of the kinetic studies indicated the termination- and transfer-free nature of the polymerization. Homopolymers with predictable molecular weights and narrow molecular weight distributions were produced, excluding the interference of the cyclobutene rings during initiation and propagation. Thermogravimetric analysis of poly(4-vinylbenzocyclobutene) in air showed a small weight gain at ~200 °C, a rapid decomposition at ~455 °C, and a gradual decomposition at ~566 °C. This behavior was attributed to the formation of radicals from the pendent benzocyclobutene functionality through o-quinodimethane intermediates and …

Go to article

Reductive Biotransformation Of Fe In Shale–Limestone Saprolite Containing Fe(Iii) Oxides And Fe(Ii)/Fe(Iii) Phyllosilicates, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, James P. Mckinley, David W. Kennedy, Steven C. Smith, Hailiang Dong Jan 2006

Reductive Biotransformation Of Fe In Shale–Limestone Saprolite Containing Fe(Iii) Oxides And Fe(Ii)/Fe(Iii) Phyllosilicates, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, James P. Mckinley, David W. Kennedy, Steven C. Smith, Hailiang Dong

United States Department of Energy: Publications

A <2.0-mm fraction of a mineralogically complex subsurface sediment containing goethite and Fe(II)/Fe(III) phyllosilicates was incubated with Shewanella putrefaciens (strain CN32) and lactate at circumneutral pH under anoxic conditions to investigate electron acceptor preference and the nature of the resulting biogenic Fe(II) fraction. Anthraquinone-2,6-disulfonate (AQDS), an electron shuttle, was included in select treatments to enhance bioreduction and subsequent biomineralization. The sediment was highly aggregated and contained two distinct clast populations: (i) a highly weathered one with ‘‘sponge-like’’ internal porosity, large mineral crystallites, and Fecontaining micas, and (ii) a dense, compact one with fine-textured Fe-containing illite and nano-sized goethite, as revealed by various forms of electron microscopic analyses. Approximately 10–15% of the Fe(III)TOT was bioreduced by …

Go to article

Kinetics Of Microbial Reduction Of Solid Phase U(Vi), Chongxuan Liu, Byong-Hun Jeon, John M. Zachara, Zheming Wang, Alice Dohnalkova, James K. Fredrickson Jan 2006

Kinetics Of Microbial Reduction Of Solid Phase U(Vi), Chongxuan Liu, Byong-Hun Jeon, John M. Zachara, Zheming Wang, Alice Dohnalkova, James K. Fredrickson

United States Department of Energy: Publications

Sodium boltwoodite (NaUO2SiO3OH•1.5 H2O) was used to assess the kinetics of microbial reduction of solid-phase U(VI) by a dissimilatory metal-reducing bacterium (DMRB), Shewanella oneidensis strain MR-1. The bioreduction kinetics was studied with Na-boltwoodite in suspension or within alginate beads in a nongrowth medium with lactate as electron donor at pH 6.8 buffered with PIPES. Concentrations of U(VI)tot and cell number were varied to evaluate the coupling of U(VI) dissolution, diffusion, and microbial activity. Microscopic and spectroscopic analyses with transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and laser-induced fluorescence spectroscopy (LIFS) collectively indicated …

Go to article

The Effect Of Calcium On Aqueous Uranium(Vi) Speciation And Adsorption To Ferrihydrite And Quartz, Patricia M. Fox, James A. Davis, John M. Zachara Jan 2006

The Effect Of Calcium On Aqueous Uranium(Vi) Speciation And Adsorption To Ferrihydrite And Quartz, Patricia M. Fox, James A. Davis, John M. Zachara

United States Department of Energy: Publications

Recent studies of uranium (VI) geochemistry have focused on the potentially important role of the aqueous species, CaUO2(CO3)32− and Ca2UO2(CO3)30(aq), on inhibition of microbial reduction and uranium(VI) aqueous speciation in contaminated groundwater. However, to our knowledge, there have been no direct studies of the effects of these species on U(VI) adsorption by mineral phases. The sorption of U(VI) on quartz and ferrihydrite was investigated in NaNO3 solutions equilibrated with either ambient air (430 ppm CO2) or 2% CO2 in the presence …

Go to article

Microscale Controls On The Fate Of Contaminant Uranium In The Vadose Zone, Hanford Site, Washington, James Mckinley, John M. Zachara, Chongxuan Liu, Steven M. Heald, Brenda Prenitzer, Brian W. Kempshall Jan 2006

Microscale Controls On The Fate Of Contaminant Uranium In The Vadose Zone, Hanford Site, Washington, James Mckinley, John M. Zachara, Chongxuan Liu, Steven M. Heald, Brenda Prenitzer, Brian W. Kempshall

United States Department of Energy: Publications

An alkaline brine containing uranyl (UO22+) leaked to the thick unsaturated zone at the Hanford Site. We examined samples from this zone at microscopic scale to determine the mode of uranium occurrence—microprecipitates of uranyl (UO22+) silicate within lithic-clast microfractures—and constructed a conceptual model for its emplacement, which we tested using a model of reactive diffusion at that scale. The study was driven by the need to understand the heterogeneous distribution of uranium and the chemical processes that controlled it. X-ray and electron microprobe imaging showed that the uranium was associated with a minority …

Go to article

Isolation Of A High-Affinity Functional Protein Complex Between Omca And Mtrc: Two Outer Membrane Decaheme C-Type Cytochromes Of Shewanella Oneidensis Mr-1, Liang Shi, Baowei Chen, Zheming Wang, Dwayne A. Elias, M. Uljana Mayer, Yuri Gorby, Shuison Ni, Brian Lower, David Kennedy, David S. Wunschel, Heather M. Mottaz, Matthew Marshall, Eric Hill, Alexander Beliaev, John M. Zachara, James K. Fredrickson, Thomas Squier Jan 2006

Isolation Of A High-Affinity Functional Protein Complex Between Omca And Mtrc: Two Outer Membrane Decaheme C-Type Cytochromes Of Shewanella Oneidensis Mr-1, Liang Shi, Baowei Chen, Zheming Wang, Dwayne A. Elias, M. Uljana Mayer, Yuri Gorby, Shuison Ni, Brian Lower, David Kennedy, David S. Wunschel, Heather M. Mottaz, Matthew Marshall, Eric Hill, Alexander Beliaev, John M. Zachara, James K. Fredrickson, Thomas Squier

United States Department of Energy: Publications

Shewanella oneidensis MR-1 is a facultatively anaerobic bacterium capable of using soluble and insoluble forms of manganese [Mn(III/IV)] and iron [Fe(III)] as terminal electron acceptors during anaerobic respiration. To assess the structural association of two outer membrane-associated c-type decaheme cytochromes (i.e., OmcA [SO1779] and MtrC [SO1778]) and their ability to reduce soluble Fe(III)-nitrilotriacetic acid (NTA), we expressed these proteins with a C-terminal tag in wild-type S. oneidensis and a mutant deficient in these genes (i.e., ∆omcA mtrC). Endogenous MtrC copurified with tagged OmcA in wild-type Shewanella, suggesting a direct association. To further evaluate their possible interaction, …

Go to article

Absolute Photoionization Cross Sections For Xe4+, Xe5+, And Xe6+ Near 13.5 Nm: Experiment And Theory, A. Aguilar, J. D. Gillaspy, G. F. Gribakin, R. A. Phaneuf, M. F. Gharaibeh, M. G. Kozlov, J. D. Bozek, A. L. D. Kilcoyne Jan 2006

Absolute Photoionization Cross Sections For Xe4+, Xe5+, And Xe6+ Near 13.5 Nm: Experiment And Theory, A. Aguilar, J. D. Gillaspy, G. F. Gribakin, R. A. Phaneuf, M. F. Gharaibeh, M. G. Kozlov, J. D. Bozek, A. L. D. Kilcoyne

United States Department of Energy: Publications

Absolute photoionization cross-section measurements for a mixture of ground and metastable states of Xe4+, Xe5+, and Xe6+ are reported in the photon energy range of 4d→nf transitions, which occur within or adjacent to the 13.5 nm window for extreme ultraviolet lithography light source development. The reported values allow the quantification of opacity effects in xenon plasmas due to these 4d→nf autoionizing states. The oscillator strengths for the 4d→4f and 4d→5f transitions in Xeq+ (q=1–6) ions are calculated using nonrelativistic Hartree-Fock …

Go to article

Resonant Soft X-Ray Scattering From Structured Polymer Nanoparticles, Tohru Araki, Harald Ade, Jeffrey M. Stubbs, Donald C. Sundberg, Gary E. Mitchell, Jeffrey B. Kortright, A. L. D. Kilcoyne Jan 2006

Resonant Soft X-Ray Scattering From Structured Polymer Nanoparticles, Tohru Araki, Harald Ade, Jeffrey M. Stubbs, Donald C. Sundberg, Gary E. Mitchell, Jeffrey B. Kortright, A. L. D. Kilcoyne

United States Department of Energy: Publications

The application of resonant soft x-ray scattering to chemically heterogeneous soft condensed matter materials is presented. Two structured styrene-acrylic polymer composite latex particles ~230 nm in diameter were utilized to delineate the potential utility of this technique. Angular scans at photon energies corresponding to strong scattering contrast between specific chemical moieties made it possible to infer the effective radii that correspond to the two polymer phases in the nanoparticles. The results show that resonant soft x-ray scattering should be a powerful complementary tool to neutron and hard x-ray scattering for the characterization of structured soft condensed matter nanomaterials.

Go to article

Synchronous Photoinjection Using A Frequency-Doubled Gain-Switched Fiber-Coupled Seed Laser And Eryb-Doped Fiber Amplifier, J. Hansknecht, M. Poelker Jan 2006

Synchronous Photoinjection Using A Frequency-Doubled Gain-Switched Fiber-Coupled Seed Laser And Eryb-Doped Fiber Amplifier, J. Hansknecht, M. Poelker

United States Department of Energy: Publications

Light at 1560 nm from a gain-switched fiber-coupled diode laser and ErYb-doped fiber amplifier was frequency doubled to obtain over 2 Waverage power at 780 nm with ~40 ps pulses and pulse repetition rate of 499 MHz. This light was used to drive the 100 kV DC high voltage GaAs photoemission gun at the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory to produce a high average current beam (100 μA) of highly spin-polarized electrons ( > 80%). This new drive-laser system represents a significant advance over laser systems used previously, providing significantly higher power and enhanced reliability.

Go to article

Photoionization And Electron-Impact Ionization Of Kr5+, M. Lu, M. F. Gharaibeh, G. Alna’Washi, R. A. Phaneuf, A. L. D. Kilcoyne, E. Levenson, A. S. Schlachter, A. M. Müller, S. Schippers, J. Jacobi, S. W. J. Scully, C. Cisneros Jan 2006

Photoionization And Electron-Impact Ionization Of Kr5+, M. Lu, M. F. Gharaibeh, G. Alna’Washi, R. A. Phaneuf, A. L. D. Kilcoyne, E. Levenson, A. S. Schlachter, A. M. Müller, S. Schippers, J. Jacobi, S. W. J. Scully, C. Cisneros

United States Department of Energy: Publications

Absolute photoionization cross sections for Kr5+ were measured in the photon energy range 74–175 eV using synchrotron radiation. For comparison, a detailed energy scan of the electron-impact ionization cross section was made in the same energy range and normalized to previously published absolute measurements. The Flexible Atomic Code and Cowan atomic structure code were used to calculate energy levels, excitation energies, and oscillator strengths for 3d→np, 3d→nf, and 4s→np autoionizing transitions from the ground and metastable states. Within the experimental uncertainty, oscillator strengths determined from the photoionization measurements are …

Go to article

Photoionization And Electron-Impact Ionization Of Kr3+, M. Lu, G. Alna’Washi, M. Habibi, M. F. Gharaibeh, R. A. Phaneuf, A. L. D. Kilcoyne, E. Levenson, A. S. Schlachter, C. Cisneros, G. Hinojosa Jan 2006

Photoionization And Electron-Impact Ionization Of Kr3+, M. Lu, G. Alna’Washi, M. Habibi, M. F. Gharaibeh, R. A. Phaneuf, A. L. D. Kilcoyne, E. Levenson, A. S. Schlachter, C. Cisneros, G. Hinojosa

United States Department of Energy: Publications

Absolute photoionization cross sections for Kr3+ were measured in the energy range 39.05–143.2 eV for single ionization and 120.6–137.7 eV for double ionization. For comparison, an electron-impact singleionization measurement was made in the energy range 43.1–179.1 eV and normalized to previously published absolute measurements. The Flexible Atomic Code and Cowan atomic structure codes were used to calculate energy levels, excitation energies and oscillator strengths for 3d→np, 3d→nf, and 4s→np autoionizing transitions from the ground and metastable states. From the single-photoionization measurements, ionization thresholds of the 2Po …

Go to article

Differences Between Tethered Polyelectrolyte Chains On Bare Mica And Hydrophobically Modified Mica, Marc Balastre, Phillip Schorr, J.-F. Argillier, Jinchuan Yang, Jimmy W. Mays, Matthew Tirrell Jan 2006

Differences Between Tethered Polyelectrolyte Chains On Bare Mica And Hydrophobically Modified Mica, Marc Balastre, Phillip Schorr, J.-F. Argillier, Jinchuan Yang, Jimmy W. Mays, Matthew Tirrell

United States Department of Energy: Publications

This study investigates the structures of layers of amphiphilic diblock copolymers of poly(t-butyl styrene)-poly- (styrene sulfonate) (PtBS-PSS) adsorbed on both the bare mica surface (hydrophilic) and an octadecyltriethoxysilane (OTE)-modified mica surface (hydrophobic). When the surface is rendered hydrophobic, the nonsoluble block exhibits stronger interaction with the surface and higher adsorbed masses are achieved. Interaction forces between two such adsorbed layers on both substrates were measured using the surface forces apparatus. The effect of salt concentration (Cs) and molecular weight (N) on the height of the self-assembled layers (L0) was examined in each case. The resulting scaling relationship is …

Go to article

Changes In Uranium Speciation Through A Depth Sequence Of Contaminated Hanford Sediments, Jeffrey Catalano, James Mckinley, John M. Zachara, Steve Heald, Steven Smith, Gordon Brown Jr. Jan 2006

Changes In Uranium Speciation Through A Depth Sequence Of Contaminated Hanford Sediments, Jeffrey Catalano, James Mckinley, John M. Zachara, Steve Heald, Steven Smith, Gordon Brown Jr.

United States Department of Energy: Publications

The disposal of basic sodium aluminate and acidic U(VI)-Cu(II) wastes in the now-dry North and South 300 A Process Ponds at the Hanford site resulted in a groundwater plume of U(VI). To gain insight into the geochemical processes that occurred during waste disposal and those affecting the current and future fate and transport of this uranium plume, the solid-phase speciation of uranium in a depth sequence of sediments from the base of the North Process Pond through the vadose zone to groundwater was investigated using standard chemical and mineralogical analyses, electron and X-ray microprobe measurements, and X-ray absorption fine structure …

Go to article

Photoionization Of Xenon Clusters, John D. Bozek, Bruce S. Rude, A. L. D. Kilcoyne Jan 2006

Photoionization Of Xenon Clusters, John D. Bozek, Bruce S. Rude, A. L. D. Kilcoyne

United States Department of Energy: Publications

High resolution photoelectron spectra of xenon clusters of about 100 atoms, measured with photon energies of 20 to 60 eV are reported. Peaks due to the clusters are observed at lower binding energies than the corresponding atomic lines and exhibit different behaviors. The peak associated with the Xe 5p1/2 state at higher binding energy is relatively unchanged with photon energy whereas the Xe 5p3/2 peak changes its shape with increasing photon energy. The change is attributed to differences in the escape depth of the electrons at different kinetic energies and the bulk and surface components of the cluster.

Go to article

Solution Properties Of 1,3-Cyclohexadiene Polymers By Laser Light Scattering And Small-Angle Neutron Scattering, Seok I. Yun, Ken Terao, Kunlun Hong, Yuri B. Melnichenko, George D. Wignall, Jimmy W. Mays, Phillip F. Britt Jan 2006

Solution Properties Of 1,3-Cyclohexadiene Polymers By Laser Light Scattering And Small-Angle Neutron Scattering, Seok I. Yun, Ken Terao, Kunlun Hong, Yuri B. Melnichenko, George D. Wignall, Jimmy W. Mays, Phillip F. Britt

United States Department of Energy: Publications

1,3-Cyclohexdiene polymers (PCHD) and their derivatives are of interest due to the six-member rings in the main chain, which are expected to impart higher mechanical strength and better thermal and chemical stability, as compared to common vinyl polymers. For example, hydrogenated PCHD has the highest glass transition temperature (tg ~ 231 °C) of all hydrocarbon polymers, and it also shows good heat, weather, impact, abrasion, and chemical resistance as well as low water absorption. In addition, PCHD has unique photochemical properties, such as excellent transparency, due to the isolated double bonds in the main chain. Also, block copolymers …

Go to article

Looped Polymer Brushes Formed By Self-Assembly Of Poly(2-Vinylpyridine)-Polystyrene-Poly(2-Vinylpyridine) Triblock Copolymers At The Solid-Fluid Interface. Kinetics Of Preferential Adsorption, Jose Alonzo, Zhenyu Huang, Ming Liu, Jimmy W. Mays, Ryan G. Toomey, Mark D. Dadmun, S. Michael Kilbey, Ii Jan 2006

Looped Polymer Brushes Formed By Self-Assembly Of Poly(2-Vinylpyridine)-Polystyrene-Poly(2-Vinylpyridine) Triblock Copolymers At The Solid-Fluid Interface. Kinetics Of Preferential Adsorption, Jose Alonzo, Zhenyu Huang, Ming Liu, Jimmy W. Mays, Ryan G. Toomey, Mark D. Dadmun, S. Michael Kilbey, Ii

United States Department of Energy: Publications

The kinetics of assembly of a series of poly(2-vinylpyridine)-polystyrene-poly(2-vinylpyridine) (PVP-b-PS-b-PVP) triblock copolymers from the selective solvent toluene onto a silicon surface has been studied using phase-modulated ellipsometry. The adsorbed amount and thickness have been determined independently as functions of time. Even though the adsorbed amount as a function of time follows the traditional two-step process that is typical of the self-assembly of diblock copolymerssthere is an initial fast adsorption followed by a slow buildup of the layer (brush regime) - the thickness shows an “overshoot” that corresponds to the brush regime. We attribute this phenomenon, not …

Go to article

Microbial Reduction Of Fe(Iii) In The Fithian And Muloorina Illites: Contrasting Extents And Rates Of Bioreduction, Jennifer L. Seabaugh, Hailiang Dong, Ravi K. Kukkadapu, Dennis D. Eberl, John P. Morton, Jinwook Kim Jan 2006

Microbial Reduction Of Fe(Iii) In The Fithian And Muloorina Illites: Contrasting Extents And Rates Of Bioreduction, Jennifer L. Seabaugh, Hailiang Dong, Ravi K. Kukkadapu, Dennis D. Eberl, John P. Morton, Jinwook Kim

United States Department of Energy: Publications

Shewanella putrefaciens CN32 reduces Fe(III) within two illites which have different properties: the Fithian bulk fraction and the <0.2 mm fraction of Muloorina. The Fithian illite contained 4.6% (w/w) total Fe, 81% of which was Fe(III). It was dominated by illite with some jarosite (~32% of the total Fe(III)) and goethite (11% of the total Fe(III)). The Muloorina illite was pure and contained 9.2% Fe, 93% of which was Fe(III). Illite suspensions were buffered at pH 7 and were inoculated with CN32 cells with lactate as the electron donor. Select treatments included anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle. Bioproduction of Fe(II) was determined by ferrozine analysis. The unreduced and bioreduced solids were characterized by Mossbauer spectroscopy, X-ray diffraction and transmission electron microscopy. The extent of Fe(III) reduction in the bulk Fithian illite was enhanced by the presence of AQDS (73%) with complete reduction of jarosite and goethite and partial reduction of illite. Mossbauer spectroscopy and chemical extraction determined that 21ÿ25% of illite-associated Fe(III) was bioreduced. The extent of bioreduction was less in the absence of AQDS (63%) and only jarosite was completely reduced with partial reduction of goethite and illite. The XRD and TEM data revealed no significant illite dissolution or biogenic minerals, suggesting that illite was reduced in the solid state and biogenic Fe(II) from jarosite and goethite was either released to aqueous solution or adsorbed onto residual solid surfaces. In contrast, only 1% of the structural Fe(III) in Muloorina illite was bioreduced. The difference in the extent and rate of bioreduction between the two illites was probably due to the difference in layer charge and the total structural Fe content between the Fithian illite (0.56 per formula) and Muloorina illite (0.87). There may be other factors contributing to the observed differences, such as expandability, surface area and the arrangements of Fe in the octahedral sheets. The results of this study have important implications for predicting microbe-induced physical and chemical changes of clay minerals in soils and sediments.

Go to article

First Prev Next Last