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 121 - 150 of 355

Full-Text Articles in Bioresource and Agricultural Engineering

Biofuels, Land, And Water: A Systems Approach To Sustainability, Gayathri Gopalakrishnan, M. Cristina Negri, Michael Wang, May Wu, Seth W. Snyder, Lorraine Lafreniere Jan 2009

Biofuels, Land, And Water: A Systems Approach To Sustainability, Gayathri Gopalakrishnan, M. Cristina Negri, Michael Wang, May Wu, Seth W. Snyder, Lorraine Lafreniere

United States Department of Energy: Publications

There is a strong societal need to evaluate and understand the sustainability of biofuels, especially because of the significant increases in production mandated by many countries, including the United States. Sustainability will be a strong factor in the regulatory environment and investments in biofuels. Biomass feedstock production is an important contributor to environmental, social, and economic impacts from biofuels. This study presents a systems approach where the agricultural, energy, and environmental sectors are considered as components of a single system, and environmental liabilities are used as recoverable resources for biomass feedstock production. We focus on efficient use of land and …

Go to article

Doe Climate Change Research Program: Strategic Plan Jan 2009

Doe Climate Change Research Program: Strategic Plan

United States 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.

Go to article

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

United States 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 …

Go to article

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

United States 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 …

Go to article

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

United States 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+ …

Go to article

Geothermal (Ground-Source) Heat Pumps: Market Status, Barriers To Adoption, And Actions To Overcome Barriers, Patrick J. Hughes Dec 2008

Geothermal (Ground-Source) Heat Pumps: Market Status, Barriers To Adoption, And Actions To Overcome Barriers, Patrick J. Hughes

United States Department of Energy: Publications

More effective stewardship of our resources contributes to the security, environmental sustainability, and economic well-being of the nation. Buildings present one of the best opportunities to economically reduce energy consumption and limit greenhouse gas emissions. Geothermal heat pumps (GHPs), sometimes called ground-source heat pumps, have been proven capable of producing large reductions in energy use and peak demand in buildings. However, GHPs have received little attention at the policy level as an important component of a national strategy. Have policymakers mistakenly overlooked GHPs, or are GHPs simply unable to make a major contribution to the national goals for various reasons? …

Go to article

Hypro: A Financial Tool For Simulating Hydrogen Infrastructure Development, Brian D. James, Peter O. Schmidt, Julie Perez Dec 2008

Hypro: A Financial Tool For Simulating Hydrogen Infrastructure Development, Brian D. James, Peter O. Schmidt, Julie Perez

United States Department of Energy: Publications

This report summarizes an analysis of the options and trade-offs for the establishment of the hydrogen production infrastructure necessary for a complete transition to hydrogen fuel cell vehicles by the year 2050. The primary tool used for the analysis is a custom created MatLab simulation tool entitled HyPro (short for Hydrogen Production). This report describes both the calculation methodology of HyPro and the assumptions and results of the baseline analysis and its many corollary cases. This study was made possible with funding from the U.S. Department of Energy (DOE).
The report and supporting primary analyses were overseen by Fred Joseck …

Go to article

Economic Development Benefits From Wind Power In Nebraska: A Report For The Nebraska Energy Office, E. Lantz Nov 2008

Economic Development Benefits From Wind Power In Nebraska: A Report For The Nebraska Energy Office, E. Lantz

United States Department of Energy: Publications

Wind power constituted more than 35% of new U.S. electric generating capacity in 2007. Common drivers of wind power include Renewable Portfolio Standards (RPS), the federal production tax credit (PTC), and rural economic development benefits. Continued expansion of the wind industry into Nebraska would bring new employment and economic development to Nebraska and the country. This report by the National Renewable Energy Laboratory (NREL) focuses on the economic development impacts that would result in Nebraska from development and operation of wind power in the state as envisioned in the U.S. Department of Energy’s (DOE’s) report 20% Wind Energy by 2030 …

Go to article

An Analysis Of The Technical And Economic Potential For Mid-Scale Distributed Wind, K. Granfield, A. Kagel, A. Appleton Oct 2008

An Analysis Of The Technical And Economic Potential For Mid-Scale Distributed Wind, K. Granfield, A. Kagel, A. Appleton

United States Department of Energy: Publications

This report examines the status, restrainers, drivers, and estimated development potential of mid-scale (10 kW to 5000 kW) distributed wind projects. This segment of the wind market has not enjoyed the same growth that central-station wind has experienced. The purpose of this report is to analyze why, and to assess the market potential for this technology under current market and policy conditions.

As discussed in section 2, one of the most significant barriers to the development of distributed wind is a general scarcity of turbine choices and turbine inventory available for purchase. Most turbine manufacturers have scaled back their involvement …

Go to article

Exploring Potential U.S. Switchgrass Production For Lignocellulosic Ethanol, Ethan B. Davis, Henriette I. Jager, Tristram O. West, Robert D. Perlack, Craig C. Brandt, Stan D. Wullschleger, Latha M. Baskaran, Erin G. Wilkerson, Mark E. Downing, Carla A. Gunderson Aug 2008

Exploring Potential U.S. Switchgrass Production For Lignocellulosic Ethanol, Ethan B. Davis, Henriette I. Jager, Tristram O. West, Robert D. Perlack, Craig C. Brandt, Stan D. Wullschleger, Latha M. Baskaran, Erin G. Wilkerson, Mark E. Downing, Carla A. Gunderson

United States Department of Energy: Publications

In response to concerns about oil dependency and the contributions of fossil fuel use to climatic change, the U.S. Department of Energy has begun a research initiative to make 20% of motor fuels biofuel based in 10 years, and make 30% of fuels bio-based by 2030. Fundamental to this objective is developing an understanding of feedstock dynamics of crops suitable for cellulosic ethanol production. This report focuses on switchgrass, reviewing the existing literature from field trials across the United States, and compiling it for the first time into a single database. Data available from the literature included cultivar and crop …

Go to article

Climate Models: An Assessment Of Strengths And Limitations, David Bader, Curt Covey, William Gutowski, Isaac Held, Kenneth Kunkel, Ronald Miller, Robin Tokmakian, Minghua Zhang Jul 2008

Climate Models: An Assessment Of Strengths And Limitations, David Bader, Curt Covey, William Gutowski, Isaac Held, Kenneth Kunkel, Ronald Miller, Robin Tokmakian, Minghua Zhang

United States Department of Energy: Publications

Scientists extensively use mathematical models of Earth’s climate, executed on the most powerful computers available, to examine hypotheses about past and present-day climates. Development of climate models is fully consistent with approaches being taken in many other fields of science dealing with very complex systems. These climate simulations provide a framework within which enhanced understanding of climate-relevant processes, along with improved observations, are merged into coherent projections of future climate change. This report describes the models and their ability to simulate current climate.
The science of climate modeling has matured through finer spatial resolution, the inclusion of a greater number …

Go to article

Genome Sequencing And Analysis Of The Biomass-Degrading Fungus Trichoderma Reesei (Syn. Hypocrea Jecorina), Diego Martinez, Randy M. Berka, Bernard Henrissat, Markku Saloheimo, Mikko Arvas, Scott E. Baker, Jarod Chapman, Olga Chertkov, Pedro M. Coutinho, Dan Cullen, Etienne G. J. Danchin, Igor V. Grigoriev, Paul Harris, Melissa Jackson, Christian P. Kubicek, Cliff S. Han, Isaac Ho, Luis F. Larrondo, Alfredo Lopez De Leon, Jon K. Magnuson, Sandy Merino, Monica Misra, Beth Nelson, Nicholas Putnam, Barbara Robbertse, Asaf A. Salamov, Monika Schmoll, Astrid Terry, Nina Thayer, Ann Westerholm-Parvinen, Conrad L. Schoch, Jian Yao, Ravi Barabote, Mary Anne Nelson, Chris Detter, David Bruce, Cheryl R. Kuske, Gary Xie, Paul Richardson, Daniel S. Rokhsar, Susan M. Lucas, Edward M. Rubin, Nigel Dunn-Coleman, Michael Ward, Thomas Brettin May 2008

Genome Sequencing And Analysis Of The Biomass-Degrading Fungus Trichoderma Reesei (Syn. Hypocrea Jecorina), Diego Martinez, Randy M. Berka, Bernard Henrissat, Markku Saloheimo, Mikko Arvas, Scott E. Baker, Jarod Chapman, Olga Chertkov, Pedro M. Coutinho, Dan Cullen, Etienne G. J. Danchin, Igor V. Grigoriev, Paul Harris, Melissa Jackson, Christian P. Kubicek, Cliff S. Han, Isaac Ho, Luis F. Larrondo, Alfredo Lopez De Leon, Jon K. Magnuson, Sandy Merino, Monica Misra, Beth Nelson, Nicholas Putnam, Barbara Robbertse, Asaf A. Salamov, Monika Schmoll, Astrid Terry, Nina Thayer, Ann Westerholm-Parvinen, Conrad L. Schoch, Jian Yao, Ravi Barabote, Mary Anne Nelson, Chris Detter, David Bruce, Cheryl R. Kuske, Gary Xie, Paul Richardson, Daniel S. Rokhsar, Susan M. Lucas, Edward M. Rubin, Nigel Dunn-Coleman, Michael Ward, Thomas Brettin

United States Department of Energy: Publications

Trichoderma reesei is the main industrial source of cellulases and hemicellulases used to depolymerize biomass to simple sugars that are converted to chemical intermediates and biofuels, such as ethanol. We assembled 89 scaffolds (sets of ordered and oriented contigs) to generate 34 Mbp of nearly contiguous T. reesei genome sequence comprising 9,129 predicted gene models. Unexpectedly, considering the industrial utility and effectiveness of the carbohydrate-active enzymes of T. reesei, its genome encodes fewer cellulases and hemicellulases than any other sequenced fungus able to hydrolyze plant cell wall polysaccharides. Many T. reesei genes encoding carbohydrate-active enzymes are distributed nonrandomly in …

Go to article

The Genome Of Laccaria Bicolor Provides Insights Into Mycorrhizal Symbiosis, F. Martin, A. Aerts, D. Ahren, A. Brun, E. G. J. Danchin, F. Duchaussoy, J. Gibon, A. Kohler, E. Lindquist, V. Pereda, A. Salamov, H. J. Shapiro, J. Wuyts, D. Blaudez, M. Buee, P. Brokstein, B. Canback, D. Cohen, P. E. Courty, P. M. Coutinho, C. Delaruelle, J. C. Detter, A. Deveau, S. Difazio, S. Duplessis, L. Fraissinet-Tachet, E. Lucic, P. Frey-Klett, C. Fourrey, I. Feussner, G. Gay, J. Grimwood, P. J. Hoegger, P. Jain, S. Kilaru, J. Labbe, Y. C. Lin, V. Legue, F. Le Tacon, R. Marmeisse, D. Melayah, B. Montanini, M. Muratet, U. Nehls, H. Niculita-Hirzel, M. P. Oudot-Le Secq, M. Peter, H. Quesneville, B. Rajashekar, M. Reich, N. Rouhier, J. Schmutz, T. Yin, M. Chalot, B. Henrissat, U. Kues, S. Lucas, Y. Van De Peer, G. K. Podila, A. Polle, P. J. Pukkila, P. M. Richardson, P. Rouze, I. R. Sanders, J. E. Stajich, A. Tunlid, G. Tuskan, I. V. Grigoriev Mar 2008

The Genome Of Laccaria Bicolor Provides Insights Into Mycorrhizal Symbiosis, F. Martin, A. Aerts, D. Ahren, A. Brun, E. G. J. Danchin, F. Duchaussoy, J. Gibon, A. Kohler, E. Lindquist, V. Pereda, A. Salamov, H. J. Shapiro, J. Wuyts, D. Blaudez, M. Buee, P. Brokstein, B. Canback, D. Cohen, P. E. Courty, P. M. Coutinho, C. Delaruelle, J. C. Detter, A. Deveau, S. Difazio, S. Duplessis, L. Fraissinet-Tachet, E. Lucic, P. Frey-Klett, C. Fourrey, I. Feussner, G. Gay, J. Grimwood, P. J. Hoegger, P. Jain, S. Kilaru, J. Labbe, Y. C. Lin, V. Legue, F. Le Tacon, R. Marmeisse, D. Melayah, B. Montanini, M. Muratet, U. Nehls, H. Niculita-Hirzel, M. P. Oudot-Le Secq, M. Peter, H. Quesneville, B. Rajashekar, M. Reich, N. Rouhier, J. Schmutz, T. Yin, M. Chalot, B. Henrissat, U. Kues, S. Lucas, Y. Van De Peer, G. K. Podila, A. Polle, P. J. Pukkila, P. M. Richardson, P. Rouze, I. R. Sanders, J. E. Stajich, A. Tunlid, G. Tuskan, I. V. Grigoriev

United States Department of Energy: Publications

Mycorrhizal symbioses—the union of roots and soil fungi—are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants. Boreal, temperate and montane forests all depend on ectomycorrhizae. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-megabase genome assembly contains ~20,000 …

Go to article

Effects Of Climate Change On Energy Production And Use In The United States, Thomas Wilbanks, Vatsal Bhatt, Daniel Bilello, Stanley Bull, James Ekmann, William Horak, Y. Joe Huang, Mark D. Levine, Michael J. Sale, David Schmalzer, Michael J. Scott Feb 2008

Effects Of Climate Change On Energy Production And Use In The United States, Thomas Wilbanks, Vatsal Bhatt, Daniel Bilello, Stanley Bull, James Ekmann, William Horak, Y. Joe Huang, Mark D. Levine, Michael J. Sale, David Schmalzer, Michael J. Scott

United States Department of Energy: Publications

Climate change is expected to have noticeable effects in the United States: a rise in average temperatures in most regions, changes in precipitation amounts and seasonal patterns in many regions, changes in the intensity and pattern of extreme weather events, and sea level rise. Some of these effects have clear implications for energy production and use. For instance, average warming can be expected to increase energy requirements for cooling and reduce energy requirements for warming. Changes in precipitation could affect prospects for hydropower, positively or negatively. Increases in storm intensity could threaten further disruptions of the sorts experienced in 2005 …

Go to article

The Role Of Multihaem Cytochromes In The Respiration Of Nitrite In Escherichia Coli And Fe(Iii) In Shewanella Oneidensis, Thomas A. Clarke, Tracey Holley, Robert S. Hartshorne, James K. Fredrickson, John M. Zachara, Liang Shi, David J. Richardson Jan 2008

The Role Of Multihaem Cytochromes In The Respiration Of Nitrite In Escherichia Coli And Fe(Iii) In Shewanella Oneidensis, Thomas A. Clarke, Tracey Holley, Robert S. Hartshorne, James K. Fredrickson, John M. Zachara, Liang Shi, David J. Richardson

United States Department of Energy: Publications

The periplasmic nitrite reductase system from Escherichia coli and the extracellular Fe (III) reductase system from Shewanella oneidensis contain multihaem c-type cytochromes as electron carriers and terminal reductases. The position and orientation of the haem cofactors in multihaem cytochromes from different bacteria often show significant conservation despite different arrangements of the polypeptide chain. We propose that the decahaem cytochromes of the iron reductase system MtrA, MtrC and OmcA comprise pentahaem ‘modules’ similar to the electron donor protein, NrfB, from E. coli. To demonstrate this, we have isolated and characterized the N-terminal pentahaem module of MtrA by preparing a …

Go to article

Significant Redistribution Of Ce 4D Oscillator Strength Observed In Photoionization Of Endohedral Ce@C+82 Ions, A. M. Müller, S. Schippers, M. Habibi, D. A. Esteves, J. C. Wang, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, L. Dunsch Jan 2008

Significant Redistribution Of Ce 4D Oscillator Strength Observed In Photoionization Of Endohedral Ce@C+82 Ions, A. M. Müller, S. Schippers, M. Habibi, D. A. Esteves, J. C. Wang, R. A. Phaneuf, A. L. D. Kilcoyne, A. Aguilar, L. Dunsch

United States Department of Energy: Publications

Mass-selected beams of atomic Ceq+ ions (q = 2, 3, 4), of C+82 and of endohedral Ce@C+82 ions were employed to study photoionization of free and encaged 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 4d photoabsorption is observed. More than half of the Ce 4d oscillator strength appears to be …

Go to article

Characterization Of Aerosols Containing Zn, Pb, And Cl From An Industrial Region Of Mexico City, Ryan C. Moffet, Yury Desyaterik, Rebecca J. Hopkins, Alexei V. Tivanski, Mary K. Gilles, Y. Wang, V. Shuthanandan, Luisa T. Molina, Rodrigo Gonzalez Abraham, Kirsten S. Johnson, Violeta Mugica, Mario J. Molina, Alexander Laskin, Kimberly A. Prather Jan 2008

Characterization Of Aerosols Containing Zn, Pb, And Cl From An Industrial Region Of Mexico City, Ryan C. Moffet, Yury Desyaterik, Rebecca J. Hopkins, Alexei V. Tivanski, Mary K. Gilles, Y. Wang, V. Shuthanandan, Luisa T. Molina, Rodrigo Gonzalez Abraham, Kirsten S. Johnson, Violeta Mugica, Mario J. Molina, Alexander Laskin, Kimberly A. Prather

United States Department of Energy: Publications

Recent ice core measurements show lead concentrations increasing since 1970, suggesting new non automobile-related sources of Pb are becoming important worldwide (1). Developing a full understanding of the major sources of Pb and other metals is critical to controlling these emissions. During the March, 2006 MILAGRO campaign, single particle measurements in Mexico City revealed the frequent appearance of particles internally mixed with Zn, Pb, Cl, and P. Pb concentrations were as high as 1.14 μg/m3 in PM10 and 0.76 μg/m3 in PM2.5. Real time measurements were used to select time periods of interest …

Go to article

Assignment Of Polarization-Dependent Peaks In Carbon K-Edge Spectra From Biogenic And Geologic Aragonite, Dong Zhou, Rebecca A. Metzler, Tolek Tyliszczak, Jinghua Guo, Mike Abrecht, Susan N. Coppersmith, P. U. P. A. Gilbert Jan 2008

Assignment Of Polarization-Dependent Peaks In Carbon K-Edge Spectra From Biogenic And Geologic Aragonite, Dong Zhou, Rebecca A. Metzler, Tolek Tyliszczak, Jinghua Guo, Mike Abrecht, Susan N. Coppersmith, P. U. P. A. Gilbert

United States Department of Energy: Publications

Many biominerals, including mollusk and echinoderm shells, avian eggshells, modern and fossil bacterial sediments, planktonic coccolithophores, and foraminifera, contain carbonates in the form of biogenic aragonite or calcite. Here we analyze biogenic and geologic aragonite using different kinds of surface- and bulksensitive X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge, as well as highresolution scanning transmission X-ray microscopy (STXM). Besides the well-known main π* and σ* carbonate peaks, we observed and fully characterized four minor peaks, at energies between the main π* and σ* peaks. As expected, the main peaks are similar in geologic …

Go to article

Challenges In Earth System Modelling: Approaches And Applications, D.J. Erickson Ill, Robert J. Oglesby, S. Elliott, W. Steffen, G. Brasseur Jan 2008

Challenges In Earth System Modelling: Approaches And Applications, D.J. Erickson Ill, Robert J. Oglesby, S. Elliott, W. Steffen, G. Brasseur

United States Department of Energy: Publications

Earth system modelling has taken on increasing importance over the past several years. These models are being used to address an increasing number of environmental and global change problems of societal concern (e.g. Adams et al., 1998; Easterling et al., 2000; Foley et al., 2003). Perhaps most commonly known is the application to possible greenhouse-gas induced warming (Hoffman et al., 2005). Other compelling problems include the climatic effects of land use changes, aerosols (including sulphate emissions, and smoke from biomass burning; Erickson et al., 1995; Oglesby et al., 1999), changing trace gas fluxes, interactions and feedbacks with the global carbon …

Go to article

Understanding The Grafting Of Telechelic Polymers On A Solid Substrate To Form Loops, Zhenyu Huang, Haining Ji, Jimmy W. Mays, Mark D. Dadmun Jan 2008

Understanding The Grafting Of Telechelic Polymers On A Solid Substrate To Form Loops, Zhenyu Huang, Haining Ji, Jimmy W. Mays, Mark D. Dadmun

United States Department of Energy: Publications

Recent experimental and theoretical studies have demonstrated that relative to singly tethered chains, the presence of polymer loops at interfaces significantly improves interfacial properties such as adhesion, friction, and wettability. In the present study, a simple system was studied to examine the formation of polymeric loops on a solid surface, where the grafting of carboxylic acid terminated telechelic polystyrene from the melt to an epoxy functionalized silicon is chosen. The impact of telechelic molecular weight, grafting temperature, and surface functionality on the telechelic attachment process is studied. It was found that grafting of the telechelic to the surface at both …

Go to article

Synthesis And Characterization Of An Abc Miktoarm Star Terpolymer Of Cyclohexadiene, Styrene, And 2-Vinylpyridine, David Uhrig, Kunlun Hong, Jimmy W. Mays, S. Michael Kilbey Ii, Phillip F. Britt Jan 2008

Synthesis And Characterization Of An Abc Miktoarm Star Terpolymer Of Cyclohexadiene, Styrene, And 2-Vinylpyridine, David Uhrig, Kunlun Hong, Jimmy W. Mays, S. Michael Kilbey Ii, Phillip F. Britt

United States Department of Energy: Publications

Several research groups have expended great effort toward the preparation of miktoarm (mixed-arm) star copolymers and terpolymers. We describe herein a novel synthesis, using anionicpolymerization,ofapoly(cyclohexadiene)[PCHD]-polystyrene [PS]-poly(2-vinylpyridine) [P2VP] miktoarm star terpolymer.

Previously, miktoarm A2B and A3B star polydiene copolymers comprised partially of poly(cyclohexadiene) have been synthesized by Tsoukatos and Hadjichristidis by employing chlorosilane linking techniques. More recently, an ABC star terpolymer of PS, polyisoprene, and PCHD was prepared by Yang and co-workers by using meta-double-diphenylethylene-based linking chemistry.

Go to article

Small Angle Neutron Scattering Study Of Conformation Of Oligo(Ethylene Glycol)-Grafted Polystyrene In Dilute Solutions: Effect Of The Backbone Length, Gang Cheng, Yuri B. Melnichenko, George D. Wignall, Fengjun Hua, Kunlun Hong, Jimmy W. Mays Jan 2008

Small Angle Neutron Scattering Study Of Conformation Of Oligo(Ethylene Glycol)-Grafted Polystyrene In Dilute Solutions: Effect Of The Backbone Length, Gang Cheng, Yuri B. Melnichenko, George D. Wignall, Fengjun Hua, Kunlun Hong, Jimmy W. Mays

United States Department of Energy: Publications

The conformation and clusterization of comblike polymers of polystyrene densely grafted with oligo(ethylene glycol) (OEG) side chains in 1.0 wt % solutions of D2O, toluene-d8, and methanol-d4 was investigated as a function of the degree of polymerization (DP) of the backbone by small angle neutron scattering (SANS). Each side chain had four EG repeat units, and the DP of the polystyrene backbone varied from 8 to 85. The global conformation of the polymers in toluene and methanol was shown to assume ellipsoidal, rigid cylindrical, or wormlike morphologies with increasing DP of the polystyrene …

Go to article

A New Fluorinated Polymer Having Two Connected Rings In The Main Chain: Synthesis And Characterization Of Fluorinated Poly(1,3-Cyclohexadiene), Tianzi Huang, Jamie M. Messman, Jimmy W. Mays Jan 2008

A New Fluorinated Polymer Having Two Connected Rings In The Main Chain: Synthesis And Characterization Of Fluorinated Poly(1,3-Cyclohexadiene), Tianzi Huang, Jamie M. Messman, Jimmy W. Mays

United States Department of Energy: Publications

The high electronegativity and small size of the fluorine atom and the high stability of C-F bonds impart interesting properties and applications to fluorine containing polymers. The unique properties of fluoropolymers include high thermal stability, improved chemical resistance, low surface energies, low coefficients of friction, and low dielectric constants. Applications of fluorinated polymers include use as noncorrosive materials, polymer processing aids, chemically resistant and antifouling coatings, as well as interlayer dielectrics. Fluorine-containing polymers can be directly synthesized via polymerization of fluorine-containing monomers or by post-polymerization modification. The latter method can be used to attach fluorinated species, such as perfluoroalkyl groups, …

Go to article

Impact Of Solvent Quality On The Density Profiles Of Looped Triblock Copolymer Brushes By Neutron Reflectivity Measurements, Zhenyu Huang, Jose Alonzo, Ming Liu, Haining Ji, Fang Yin, Grant D. Smith, Jimmy W. Mays, S. Michael Kilbey Ii, Mark D. Dadmun Jan 2008

Impact Of Solvent Quality On The Density Profiles Of Looped Triblock Copolymer Brushes By Neutron Reflectivity Measurements, Zhenyu Huang, Jose Alonzo, Ming Liu, Haining Ji, Fang Yin, Grant D. Smith, Jimmy W. Mays, S. Michael Kilbey Ii, Mark D. Dadmun

United States Department of Energy: Publications

Preferential adsorption of poly(2-vinylpyridine)-deuterated polystyrene-poly(2-vinylpyridine) (PVP-dPS-PVP) triblock copolymers from toluene onto silicon leads to the formation of dPS loops tethered by the PVP end blocks. Using neutron reflectometry, we have determined the segment density profiles of these looped polymer brushes in toluene, a good solvent for the dPS block, and in cyclohexane at 20 °C (poor solvent), 32 °C, (near-Θ solvent), and 50 °C (marginal solvent). While the swelling behavior qualitatively agrees with that observed for singly grafted brushes, there are interesting differences in the local structural details: In a good solvent, the segment density profiles are composed of an …

Go to article

Hierarchical Assemblies Of Block-Copolymer-Based Supramolecules In Thin Films, Shih-Huang Tung, Nisha C. Kalarickal, Jimmy W. Mays, Ting Xu Jan 2008

Hierarchical Assemblies Of Block-Copolymer-Based Supramolecules In Thin Films, Shih-Huang Tung, Nisha C. Kalarickal, Jimmy W. Mays, Ting Xu

United States Department of Energy: Publications

The hierarchical assemblies of supramolecules, which consisted of polystyrene-b-poly(4- vinylpyridine) (PS-b-P4VP) with 3-pentadecylphenol (PDP) hydrogen-bonded to the 4VP, were investigated in thin films after solvent annealing in a chloroform atmosphere. The synergistic coassembly of PS-b-P4VP and PDP was utilized to generate oriented hierarchical structures in thin films. Hierarchical assemblies, including lamellae-within-lamellae and cylinders-within-lamellae, were simultaneously ordered and oriented from a few to several tens of nanometers over macroscopic length scales. The macroscopic orientation of supramolecular assembly depends on the P4VP(PDP) fraction and can be tailored by varying the PDP to P4VP ratio without interfering …

Go to article

Association And Structure Of Thermosensitive Comblike Block Copolymers In Aqueous Solutions, Gang Cheng, Fengjun Hua, Yuri B. Melnichenko, Kunlun Hong, Jimmy W. Mays, Boualem Hammouda, George D. Wignall Jan 2008

Association And Structure Of Thermosensitive Comblike Block Copolymers In Aqueous Solutions, Gang Cheng, Fengjun Hua, Yuri B. Melnichenko, Kunlun Hong, Jimmy W. Mays, Boualem Hammouda, George D. Wignall

United States Department of Energy: Publications

The structures and association properties of thermosensitive block copolymers of poly(methoxyoligo( ethylene glycol) norbornenyl esters) in D2O were investigated by small angle neutron scattering (SANS). Each block is a comblike polymer with a polynorbornene (PNB) backbone and oligo ethylene glycol (OEG) side chains (one side chain per NB repeat unit). The chemical formula of the block copolymer is (OEG3NB) 79- (OEG6.6NB) 67, where subscripts represent the degree of polymerization (DP) of OEG and NB in each block. The polymer concentration was fixed at 2.0 wt % and the structural changes were investigated …

Go to article

Biogeochemical Processes In Ethanol Stimulated Uranium-Contaminated Subsurface Sediments, Santosh R. Mohanty, Bharati Kollah, David B. Hedrick, Aaron D. Peacock, Ravi K. Kukkadapu, E. E. Roden Jan 2008

Biogeochemical Processes In Ethanol Stimulated Uranium-Contaminated Subsurface Sediments, Santosh R. Mohanty, Bharati Kollah, David B. Hedrick, Aaron D. Peacock, Ravi K. Kukkadapu, E. E. Roden

United States Department of Energy: Publications

A laboratory incubation experiment was conducted with uranium contaminated subsurface sediment to assess the geochemical and microbial community response to ethanol amendment. A classical sequence of terminal electron-accepting processes (TEAPs) was observed in ethanol-amended slurries, with NO3- reduction, Fe(III) reduction, SO42- reduction, and CH4 production proceeding in sequence until all of the added 13Cethanol (9 mM) was consumed. Approximately 60% of the U(VI) content of the sediment was reduced during the period of Fe(III) reduction. No additional U(VI) reduction took place during the sulfate-reducing and methanogenic phases of the experiment. Only gradual reduction of NO …

Go to article

Reduction Of Tc(Vii) By Fe(Ii) Sorbed On Al (Hydr)Oxides, T. Peretyazhko, J.M. Zachara, S.M. Heald, Ravi K. Kukkadapu, C. Liu, A.E. Plymale, C.T. Resch Jan 2008

Reduction Of Tc(Vii) By Fe(Ii) Sorbed On Al (Hydr)Oxides, T. Peretyazhko, J.M. Zachara, S.M. Heald, Ravi K. Kukkadapu, C. Liu, A.E. Plymale, C.T. Resch

United States Department of Energy: Publications

Under oxic conditions, Tc exists as the soluble, weakly sorbing pertechnetate [TcO4-] anion. The reduced form of technetium, Tc(IV), is stable in anoxic environments and is sparingly soluble as TcO2 ·nH2O(s). Here we investigate the heterogeneous reduction of Tc(VII) by Fe(II) adsorbed on Al (hydr)oxides [diaspore (α-AlOOH) and corundum (α-Al2O3)]. Experiments were performed to study the kinetics of Tc(VII) reduction, examine changes in Fe surface speciation during Tc(VII) reduction (Mössbauer spectroscopy), and identify the nature of Tc(IV)-containing reaction products (X-ray absorption spectroscopy). We found that Tc(VII) was completely …

Go to article

Long-Term Dynamics Of Uranium Reduction/Reoxidation Under Low Sulfate Conditions, John Komlos, Aaron Peacock, Ravi K. Kukkadapu, Peter R. Jaffe Jan 2008

Long-Term Dynamics Of Uranium Reduction/Reoxidation Under Low Sulfate Conditions, John Komlos, Aaron Peacock, Ravi K. Kukkadapu, Peter R. Jaffe

United States Department of Energy: Publications

The biological reduction and precipitation of uranium in groundwater has the potential to prevent uranium migration from contaminated sites. Although previous research has shown that uranium bioremediation is maximized during iron reduction, little is known on how long-term iron/uranium reducing conditions can be maintained. Questions also remain about the stability of uranium and other reduced species after a long-term biostimulation scheme is discontinued and oxidants (i.e., oxygen) re-enter the bioreduced zone. To gain further insights into these processes, four columns, packed with sediment containing iron as Fe-oxides (mainly Al-goethite) and silicate Fe (Fe-containing clays), were operated in the laboratory under …

Go to article

Kinetics Of Reduction Of Fe(Iii) Complexes By Outer Membrane Cytochromes Mtrc And Omca Of Shewanella Oneidensis Mr-1, Zheming Wang, Chongxuan Liu, Xuelin Wang, Matthew J. Marshall, John M. Zachara, Kevin M. Rosso, Michel Dupuis, James K. Fredrickson, Steve Heald, Liang Shi Jan 2008

Kinetics Of Reduction Of Fe(Iii) Complexes By Outer Membrane Cytochromes Mtrc And Omca Of Shewanella Oneidensis Mr-1, Zheming Wang, Chongxuan Liu, Xuelin Wang, Matthew J. Marshall, John M. Zachara, Kevin M. Rosso, Michel Dupuis, James K. Fredrickson, Steve Heald, Liang Shi

United States Department of Energy: Publications

Because of their cell surface locations, the outer membrane c-type cytochromes MtrC and OmcA of Shewanella oneidensis MR-1 have been suggested to be the terminal reductases for a range of redox-reactive metals that form poorly soluble solids or that do not readily cross the outer membrane. In this work, we determined the kinetics of reduction of a series of Fe(III) complexes with citrate, nitrilotriacetic acid (NTA), and EDTA by MtrC and OmcA using a stopped-flow technique in combination with theoretical computation methods. Stopped-flow kinetic data showed that the reaction proceeded in two stages, a fast stage that was completed …

Go to article

First Prev Next Last