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University of Nebraska - Lincoln

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Articles 1201 - 1230 of 1371

Full-Text Articles in Bioresource and Agricultural Engineering

Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman Jan 2001

Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman

United States Department of Energy: Publications

The kinetics of dissimilatory reduction of goethite (RFeOOH) was studied in batch cultures of a groundwater bacterium, Shewanella putrefaciens, strain CN32 in pH 7 bicarbonate buffer. The rate and extent of goethite reduction were measured as a function of electron acceptor (goethite) and donor (lactate) concentrations. Increasing goethite concentrations increased both the rate and extent of Fe(III) reduction when cell and lactate concentrations were held constant. However, constant initial reduction rates were observed after normalization to the Fe(II) sorption capacity of FeOOH, suggesting that the bacterial reduction rate was first order with respect to surface site concentration. Increasing …

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Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown Jan 2001

Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown

United States Department of Energy: Publications

The influence of Fe(II) on the dissimilatory bacterial reduction of an Fe(III) aqueous complex (Fe(III)-citrateaq) was investigated using Shewanella putrefaciens strain CN32. The sorption of Fe(II) on CN32 followed a Langmuir isotherm. Least-squares fitting gave a maximum sorption capacity of Qmax = 4.19 x 10-3 mol/1012 cells (1.19 mmol/ m2 of cell surface area) and an affinity coefficient of log K = 3.29. The growth yield of CN32 with respect to Fe(III)aq reduction showed a linear trend with an average value of 5.24 (±0.12) x 109 cells/mmol of Fe(III). The reduction of …

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Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara Jan 2001

Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara

United States Department of Energy: Publications

Monod kinetic parameters (Ks, µmax, and Y) that are estimated from batch experimental data can have large uncertainties due to linear correlations between them. The degree of correlation and the resulting uncertainties of the Monod parameters are functions of the initial experimental conditions, the values of the parameters, the type and magnitude of measurement errors, and the sampling number. Careful manipulation of experimental conditions can reduce the correlations between Monod parameters allowing for the estimation of Monod kinetic parameters with the lowest degree of uncertainty. By dimensionless analysis, the correlation and relative standard deviations of Monod parameters …

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Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris Jan 2001

Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris

United States Department of Energy: Publications

We have investigated the effect of changes in solution chemistry on the nature of uranyl sorption complexes on montmorillonite (SAz-1) at different surface coverages (1.43–53.6 µmol/g). Uranyl uptake onto SAz-1 between pH 3 and 7 was determined in both titration and batch-mode experiments. These pH values result in solutions that contain a range of monomeric and oligomeric aqueous uranyl species. Continuous-wave and timeresolved emission spectroscopies were used to investigate the nature of U(VI) sorbed to SAz-1. A discrete set of uranyl surface complexes has been identified over a wide range of pH values at these low to moderate coverages. For …

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Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas Jan 2001

Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas

United States Department of Energy: Publications

The carbon 1s photoelectron spectrum of ethane, C2H6, has been measured at a photon energy of 329 eV and an instrumental resolution of 70 meV. The spectrum shows a rich vibrational structure which is resolved using least-squares fits to the data. Only C-H stretching and CCH bending modes contribute significantly to the spectrum. The lack of excitation of the C-C stretching mode is explained in terms of changes in hybridization at the spectator carbon. To investigate the possibility of incomplete localization of the core hole, the spectra of C2H6 and C2D …

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Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman Jan 2001

Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman

United States Department of Energy: Publications

Trace metals associate with Fe(III) oxides as adsorbed or coprecipitated species, and consequently, the biogeochemical cycles of iron and the trace metals are closely linked. This communication investigated the solubilization of coprecipitated Co(III) and Ni(II) from goethite (α-FeOOH) during dissimilatory bacterial iron reduction to provide insights on biogeochemical factors controlling trace-element fluxes in anoxic environments. Suspensions of homogeneously substituted Co-FeOOH (50 mmol/L as Co0.01Fe0.99OOH; 57Co-labeled) in eight different buffer/media solutions were inoculated with a facultative, metal-reducing bacteria isolated from groundwater (Shewanella putrefacians CN32), and incubated under strictly anaerobic conditions for periods up to 32 …

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Estimation Of Reference Crop Evapotranspiration Using Fuzzy State Models, Lameck O. Odhiambo, R. E. Yoder, D. C. Yoder Jan 2001

Estimation Of Reference Crop Evapotranspiration Using Fuzzy State Models, Lameck O. Odhiambo, R. E. Yoder, D. C. Yoder

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Daily evapotranspiration (ET) rates are needed for irrigation scheduling. Owing to the difficulty of obtaining accurate field measurements, ET rates are commonly estimated from weather parameters. A few empirical or semi–empirical methods have been developed for assessing daily reference crop ET, which is converted to actual crop ET using crop coefficients. The FAO Penman–Monteith method, which is now accepted as the standard method for the computation of daily reference ET, is sophisticated. It requires several input parameters, some of which have no actual measurements but are estimated from measured weather parameters. In this study, we examined the suitability of fuzzy …

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Optimization Of Fuzzy Evapotranspiration Model Through Neural Training With Input–Output Examples, Lameck O. Odhiambo, R. E. Yoder, D. C. Yoder, J. W. Hines Jan 2001

Optimization Of Fuzzy Evapotranspiration Model Through Neural Training With Input–Output Examples, Lameck O. Odhiambo, R. E. Yoder, D. C. Yoder, J. W. Hines

Department of Agricultural and Biological Systems Engineering: Faculty Publications

In a previous study, we demonstrated that fuzzy evapotranspiration (ET) models can achieve accurate estimation of daily ET comparable to the FAO Penman–Monteith equation, and showed the advantages of the fuzzy approach over other methods. The estimation accuracy of the fuzzy models, however, depended on the shape of the membership functions and the control rules built by trial–and–error methods. This paper shows how the trial and error drawback is eliminated with the application of a fuzzy–neural system, which combines the advantages of fuzzy logic (FL) and artificial neural networks (ANN). The strategy consisted of fusing the FL and ANN on …

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Wind Powering America: Clean Energy For The 21st Century Apr 2000

Wind Powering America: Clean Energy For The 21st Century

United States Department of Energy: Publications

Since earliest recorded history, wind power has been used to move ships, grind grain, and pump water. Today, wind power is also being used to provide electricity to homes, schools, businesses, and entire communities. More than half the United States have wind resources that could support the development of utility scale wind power plants.

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Geothermal Heat Pumps In K–12 Schools: A Case Study Of The Lincoln, Nebraska Schools, John A. Shonder, Michaela A. Martin, Patrick J. Hughes, Jeff Thornton Apr 2000

Geothermal Heat Pumps In K–12 Schools: A Case Study Of The Lincoln, Nebraska Schools, John A. Shonder, Michaela A. Martin, Patrick J. Hughes, Jeff Thornton

United States Department of Energy: Publications

Geothermal heat pumps (GHPs) have been shown to have a number of benefits over other technologies used to heat and cool buildings and provide hot water, combining high levels of occupant comfort with low operating and maintenance costs. Public facilities represent an increasingly important market for GHPs, and schools are a particularly good application, given the large land area that normally surrounds them. Nevertheless, some barriers remain to the increased use of GHPs in institutional and commercial applications. First, because GHPs are perceived as having higher installation costs than other space conditioning technologies, they are sometimes not considered as an …

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Use Of The Generalized Integral Transform Method For Solving Equations Of Solute Transport In Porous Media, Chongxuan Liu, Jim E. Szecsody, John M. Zachara, William P. Ball Jan 2000

Use Of The Generalized Integral Transform Method For Solving Equations Of Solute Transport In Porous Media, Chongxuan Liu, Jim E. Szecsody, John M. Zachara, William P. Ball

United States Department of Energy: Publications

The generalized integral transform technique (GITT) is applied to solve the one-dimensional advection-dispersion equation (ADE) in heterogeneous porous media coupled with either linear or nonlinear sorption and decay. When both sorption and decay are linear, analytical solutions are obtained using the GITT for one-dimensional ADEs with spatially and temporally variable flow and dispersion coefficient and arbitrary initial and boundary conditions. When either sorption or decay is nonlinear the solutions to ADEs with the GITT are hybrid analytical-numerical. In both linear and nonlinear cases, the forward and inverse integral transforms for the problems described in the paper are apparent and straightforward. …

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Mineral Transformation Associated With The Microbial Reduction Of Magnetite, Hailiang Dong, James K. Fredrickson, David W. Kennedy, John M. Zachara, Ravi K. Kukkadapu, Tullis C. Onstott Jan 2000

Mineral Transformation Associated With The Microbial Reduction Of Magnetite, Hailiang Dong, James K. Fredrickson, David W. Kennedy, John M. Zachara, Ravi K. Kukkadapu, Tullis C. Onstott

United States Department of Energy: Publications

Although dissimilatory iron reducing bacteria (DIRB) are capable of reducing a number of metals in oxides and soluble forms, the factors controlling the raterextent of magnetite reduction and the nature of the mineral products resulting from magnetite reduction are not well understood. This study was carried out to investigate mechanisms and biogeochemical processes occurring during magnetite reduction by the DIRB, Shewanella putrefaciens strains CN32 and MR-1. Reduction experiments were performed with biogenic and synthetic magnetite in well-defined solutions. Biogenic magnetite was generated via microbial reduction of hydrous ferric oxide (HFO). Biogenic magnetite in solutions buffered with either bicarbonate (HCO3 …

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Reduction Of U(Vi) In Goethite (Α-Feooh) Suspensions By A Dissimilatory Metal-Reducing Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Martine Duff, Yuri Gorby, Shu-Mei Li, Kenneth Krupka Jan 2000

Reduction Of U(Vi) In Goethite (Α-Feooh) Suspensions By A Dissimilatory Metal-Reducing Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Martine Duff, Yuri Gorby, Shu-Mei Li, Kenneth Krupka

United States Department of Energy: Publications

Dissimilatory metal-reducing bacteria (DMRB) can utilize Fe(III) associated with aqueous complexes or solid phases, such as oxide and oxyhydroxide minerals, as a terminal electron acceptor coupled to the oxidation of H2 or organic substrates. These bacteria are also capable of reducing other metal ions including Mn(IV), Cr(VI), and U(VI), a process that has a pronounced effect on their solubility and overall geochemical behavior. In spite of considerable study on an individual basis, the biogeochemical behavior of multiple metals subject to microbial reduction is poorly understood. To probe these complex processes, the reduction of U(VI) by the subsurface bacterium, Shewanella …

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Determination Of Semivariogram Models To Krige Hourly And Daily Solar Irradiance In Western Nebraska*, G.G. Merino, D. Jones, David Stooksbury, Kenneth Hubbard Jan 2000

Determination Of Semivariogram Models To Krige Hourly And Daily Solar Irradiance In Western Nebraska*, G.G. Merino, D. Jones, David Stooksbury, Kenneth Hubbard

Department of Agricultural and Biological Systems Engineering: Faculty Publications

In this paper, linear and spherical semivariogram models were determined for use in kriging hourly and daily solar irradiation for every season of the year. The data used to generate the models were from 18 weather stations in western Nebraska. The models generated were tested using cross validation. The performance of the spherical and linear semivariogram models were compared with each other and also with the semivariogram models based on the best fit to the sample semivariogram of a particular day or hour. There were no significant differences in the performance of the three models. This result and the comparable …

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The Effect Of Biogenic Fe(Ii) On The Stability And Sorption Of Co(Ii)Edta22 To Goethite And A Subsurface Sediment, John M. Zachara, Steven Smith, James K. Fredrickson Jan 2000

The Effect Of Biogenic Fe(Ii) On The Stability And Sorption Of Co(Ii)Edta22 To Goethite And A Subsurface Sediment, John M. Zachara, Steven Smith, James K. Fredrickson

United States Department of Energy: Publications

Laboratory experiments were conducted with suspensions of goethite (α-FeOOH) and a subsurface sediment to assess the influence of bacterial iron reduction on the fate of Co(II)EDTA2-, a representative metal-ligand complex of intermediate stability (log KCo(II)EDTA = 17.97). The goethite was synthetic (ca. 55 m2/g) and the sediment was a Pleistocene age, Fe(III) oxide-containing material from the Atlantic coastal plain (Milford). Shewanella alga strain BrY, a dissimilatory iron reducing bacterium (DIRB), was used to promote Fe(III) oxide reduction. Sorption isotherms and pH adsorption edges were measured for Co2+, Fe2+, Co(II)EDTA2-, …

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Effect Of Sample Complexity On Quantification Of Analytes In Aqueous Samples By Near-Infrared Spectroscopy, Mark R. Riley, Mark A. Arnold, David W. Murhammer Jan 2000

Effect Of Sample Complexity On Quantification Of Analytes In Aqueous Samples By Near-Infrared Spectroscopy, Mark R. Riley, Mark A. Arnold, David W. Murhammer

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This study was undertaken to quantitate the impact of increasing sample complexity on near-infrared spectroscopic (NIRS) measurements of small molecules in aqueous solutions with varying numbers of components. Samples with 2, 6, or 10 varying components were investigated. Within the 10-component samples, three analytes were quantified with errors below 6% and seven of the analytes were quantified with errors below 10%. An increase in the number of varying components can substantially increase the error associated with measurement. A comparison of measurement errors across sample sets, as gauged by the standard error of prediction (SEP), reveals that an increase in the …

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Method And Apparatus For Production Of Levulinic Acid Via Reactive Extrusion, Viswasrao Ghorpade, Milford Hanna Jan 1999

Method And Apparatus For Production Of Levulinic Acid Via Reactive Extrusion, Viswasrao Ghorpade, Milford Hanna

Industrial Agricultural Products Center: Publications and Information

The present invention relates to a continuous process for preparing levulinic acid from starch in a reactive extrusion process. In a preferred embodiment, the extrusion takes place in a twin-screw extruder having a plurality of temperature zones wherein the starch slurry is preconditioned, extruded, filter pressed, reboiled, vacuum distilled, condensed, centrifuged, whereby the waste effluent from the centrifugation is reprocessed upstream to the preconditioning stage.

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Influence Of Aqueous And Solid-Phase Fe(Ii) Complexants On Microbial Reduction Of Crystalline Iron(Iii) Oxides, Matilde Urrutia, Eric E. Roden, John M. Zachara Jan 1999

Influence Of Aqueous And Solid-Phase Fe(Ii) Complexants On Microbial Reduction Of Crystalline Iron(Iii) Oxides, Matilde Urrutia, Eric E. Roden, John M. Zachara

United States Department of Energy: Publications

The influence of aqueous (NTA and EDTA) and solidphase (aluminum oxide, layer silicates) Fe(II) complexants on the long-term microbial reduction of synthetic goethite by Shewanella alga strain BrY was studied. NTA enhanced goethite reduction by promoting aqueous Fe(II) accumulation, in direct proportion to its concentration in culture medium (0.01-5 mM). In contrast, EDTA failed to stimulate goethite reduction at concentrations e1 mM, and 5 mM EDTA enhanced the final extent of reduction by only 25% in relation to nonchelator controls. The minor effect of EDTA compared to NTA, despite the greater stability of the Fe(II)- EDTA complex, likely resulted from …

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Report Of The Poplar Working Group, Steve Strauss Jan 1999

Report Of The Poplar Working Group, Steve Strauss

United States Department of Energy: Publications

Poplars consist of all species of the genus Populus, including cottonwoods, aspens, and the many interspecies hybrids in common use (Dickmann and Stuart 1983). Our working group focused on the fungal pathogens, arthropod herbivores, and weed competitors of Populus in the United States. However, bacterial and viral diseases of Populus are significant in Europe, and genetic engineering approaches toward their control or management are being studied. The key aspects of poplar biology important to understanding the use of pest resistance genes are described below.

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2h Solid-State Nmr Investigation Of Terephthalate Dynamics And Orientation In Mixed-Anion Hydrotalcite-Like Compounds, Robert S. Maxwell, Ravi K. Kukkadapu, James E. Amonette, Herman Cho Jan 1999

2h Solid-State Nmr Investigation Of Terephthalate Dynamics And Orientation In Mixed-Anion Hydrotalcite-Like Compounds, Robert S. Maxwell, Ravi K. Kukkadapu, James E. Amonette, Herman Cho

United States Department of Energy: Publications

The dynamics and orientations of interlayer terephthalate (TA) anions in mixed-anion hydrotalcite-like compounds [Mg1-x Alx(OH)2](AyB1-y)x/2•nH2O, where A = p-C6D4(COO)22- and B ) CO32-] were investigated by 2H variable-temperature solid-state nuclear magnetic resonance (NMR) spectroscopy. Two dominant 003 d spacings, 7.6 and 14.2 Å, were observed by X-ray diffraction (XRD) in these samples, suggesting that there were at least two interlayer environments. Over the range of layer charges studied (0.37 ≥ x ≥ 0.29), the intensity …

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Metal Oxide Surfaces And Their Interactions With Aqueous Solutions And Microbial Organisms, Gordon E. Brown Jr., Victor Henrich, William Casey, David Clark, Carrick Eggleston, Andrew Felmy Andrew Felmy, D. Wayne Goodman, Michael Gratzel, Gary Maciel, Maureen I. Mccarthy, Kenneth H. Nealson, Dimitri Sverjensky, Michael Toney, John M. Zachara Jan 1999

Metal Oxide Surfaces And Their Interactions With Aqueous Solutions And Microbial Organisms, Gordon E. Brown Jr., Victor Henrich, William Casey, David Clark, Carrick Eggleston, Andrew Felmy Andrew Felmy, D. Wayne Goodman, Michael Gratzel, Gary Maciel, Maureen I. Mccarthy, Kenneth H. Nealson, Dimitri Sverjensky, Michael Toney, John M. Zachara

United States Department of Energy: Publications

During the past decade, interest in chemical reactions occurring at metal oxide-aqueous solution interfaces has increased significantly because of their importance in a variety of fields, including atmospheric chemistry, heterogeneous catalysis and photocatalysis, chemical sensing, corrosion science, environmental chemistry and geochemistry, metallurgy and ore beneficiation, metal oxide crystal growth, soil science, semiconductor manufacturing and cleaning, and tribology. The metal oxide-aqueous solution interface is reactive due to acid-base, ligand-exchange, and/or redox chemistry involving protons (hydronium ions), hydroxyl groups, aqueous metal ions, and aqueous organic species and also complexes among these species. Interfacial localization of those species (adsorption) may result from electrostatic, …

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Climate Change Impacts On The Potential Productivity Of Corn And Winter Wheat In Their Primary United States Growing Regions, Robert Brown, Norman Rosenberg Jan 1999

Climate Change Impacts On The Potential Productivity Of Corn And Winter Wheat In Their Primary United States Growing Regions, Robert Brown, Norman Rosenberg

United States Department of Energy: Publications

We calculate the impacts of climate effects inferred from three atmospheric general circulation models (GCMs) at three levels of climate change severity associated with change in global mean temperature (GMT) of 1.0, 2.5 and 5.0 _C and three levels of atmospheric CO2 concentration ([CO2]) – 365 (no CO2 fertilization effect), 560 and 750 ppm – on the potential production of dryland winter wheat (Triticum aestivum L.) and corn (Zea mays L.) for the primary (current) U.S. growing regions of each crop. This analysis is a subset of the Global Change Assessment Model (GCAM) which has …

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Below-Ground Respiratory Responses Of Sugar Maple And Red Maple Saplings To Atmospheric Co2 Enrichment And Elevated Air Temperature, Nelson Edwards, Richard Norby Jan 1999

Below-Ground Respiratory Responses Of Sugar Maple And Red Maple Saplings To Atmospheric Co2 Enrichment And Elevated Air Temperature, Nelson Edwards, Richard Norby

United States Department of Energy: Publications

The research described in this paper represents a part of a much broader research project with the general objective of describing the effects of elevated [CO2] and temperature on tree growth, physiological processes, and ecosystem-level processes. The specific objective of this research was to examine the below-ground respiratory responses of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) seedlings to elevated atmospheric [CO2] and temperature. Red maple and sugar maple seedlings were planted in the ground in each of 12 open-top chambers and exposed from 1994 through 1997 to ambient air …

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Binder Containing Plant Protein And Densified Refuse Fuel Cubes Made Using Same And Methods Of Making Them, Jerry D. Eastin, David Jones, Darin Dux, Harold Earl Egger Jan 1998

Binder Containing Plant Protein And Densified Refuse Fuel Cubes Made Using Same And Methods Of Making Them, Jerry D. Eastin, David Jones, Darin Dux, Harold Earl Egger

Department of Agricultural and Biological Systems Engineering: Faculty Publications

To form a binder from naturally occurring products or a fuel brick or pellet using the binder without extraction or purification steps, the binder utilizes proteins from the germ or endosperm of cereal grasses or from the seed of buckwheat, oil seed plants, Amaranthus or leguminous plants or from leaves or from grain stillage. The protein has a thermoplastic microstructure with linear polymers of molecular weight of at least 2,000 linked with peptide linkages of at least 50 in number. The binder is mixed with waste such as municipal waste without further processing and processed in a pelleting machine.

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Biogenic Iron Mineralization Accompanying The Dissimilatory Reduction Of Hydrous Ferric Oxide By A Groundwater Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Hailang Dong, Tullis Onstott, Nancy Hinman, Shu-Mei Li Jan 1998

Biogenic Iron Mineralization Accompanying The Dissimilatory Reduction Of Hydrous Ferric Oxide By A Groundwater Bacterium, James K. Fredrickson, John M. Zachara, David Kennedy, Hailang Dong, Tullis Onstott, Nancy Hinman, Shu-Mei Li

United States Department of Energy: Publications

Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens, strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic …

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The Effects Of Catalyst, Free Fatty Acids, And Water On Transecterification Of Beef Tallow, Fangrui Ma, L. D. Clements, Milford Hanna Jan 1998

The Effects Of Catalyst, Free Fatty Acids, And Water On Transecterification Of Beef Tallow, Fangrui Ma, L. D. Clements, Milford Hanna

Industrial Agricultural Products Center: Publications and Information

Transesterification of beef tallow and methanol is affected by many factors. Catalyst, free fatty acids, and water in beef tallow, and reaction time were investigated. Sodium hydroxide (NUOH) was a more effective catalyst than sodium methoxide (NaMeOj. NaOH and NaMeO reached their maximum activities at 0.3% and 0.5%, w/w of beef tallow, respectively. The presence of water had more negative effect on transesterification than did the presence of free fatty acids (FFA). For best results, the water content of beef tallow should be kept not beyond 0.0696, w/w. FFA content of beef tallow should be kept below 0.596, w/w. The …

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Influence Of Iron Oxide Inclusion Shape On Coii/Iiiedta Reactive Transport Through Spatially Heterogeneous Sediment, James E. Szecsody, Ashley Chilakapati, John M. Zachara, Amanda Garvin Jan 1998

Influence Of Iron Oxide Inclusion Shape On Coii/Iiiedta Reactive Transport Through Spatially Heterogeneous Sediment, James E. Szecsody, Ashley Chilakapati, John M. Zachara, Amanda Garvin

United States Department of Energy: Publications

Multisolute reactive transport was investigated in chemically heterogeneous systems to determine the influence of the shapes of the reactive heterogeneities (iron oxide inclusions) by comparison of two-dimensional heterogeneous experiments with spatially averaged models that had differing inclusion characterization. Eleven reactions were considered in this system, starting with absorption of the initial solute (CoIIEDTA) to Fe oxides, followed by two competing surface reactions: oxidation forming CoIIIEDTA and Fe dissolution forming FeIIIEDTA and Co2+. Spatial moments of the eight mobile species were compared between data and models. One spatially averaged model (homogenous equivalent), which incorporated inclusion …

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Bacterial Reduction Of Crystalline Fe3+ Oxides In Single Phase Suspensions And Subsurface Materials, John M. Zachara, James K. Fredrickson, Shu-Mei Li, David W. Kennedy, Steven C. Smith, Paul L. Gassman Jan 1998

Bacterial Reduction Of Crystalline Fe3+ Oxides In Single Phase Suspensions And Subsurface Materials, John M. Zachara, James K. Fredrickson, Shu-Mei Li, David W. Kennedy, Steven C. Smith, Paul L. Gassman

United States Department of Energy: Publications

Microbiologic reduction of synthetic and geologic Fe3+ oxides associated with four Pleistocene- age, Atlantic coastal plain sediments was investigated using a dissimilatory Fe reducing bacterium (Shewanella putrefaciens, strain CN32) in bicarbonate buffer. Experiments investigated whether phosphate and anthraquinone-2, 6-disulfonate, (AQDS, a humic acid analogue) influenced the extent of crystalline Fe3+ oxide bioreduction and whether crystalline Fe3+ oxides in geologic materials are more or less reducible than comparable synthetic phases. Anaerobic incubations (108 organisms/mL) were performed both with and without PO4 and AQDS that functions as an electron repository and shuttle. The production of …

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Chemical Information On Tank Supernatants, Cs Adsorption From Tank Liquids Onto Hanford Sediments, And Field Observations Of Cs Migration From Past Tank Leaks, R. J. Serne, John M. Zachara, D. S. Burke Jan 1998

Chemical Information On Tank Supernatants, Cs Adsorption From Tank Liquids Onto Hanford Sediments, And Field Observations Of Cs Migration From Past Tank Leaks, R. J. Serne, John M. Zachara, D. S. Burke

United States Department of Energy: Publications

Borehole gamma-logging profiles beneath the SX-Tank Farm suggest that contamination from Cs-137 extends to at least a depth of 40 m (130 ft), and may extend even deeper. What is presently not known is the pathway that Cs-137 has taken to reach these depths. In this report we provide an analysis of the chemistry of tank supernates with emphasis on the REDOX waste stream disposed in SX tanks, Cs chemistry in aqueous solutions and adsorption properties onto minerals, available data on Cs adsorption onto Hanford sediments, and information on Cs migration from other Hanford tank leaks that have been studied. …

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Matrix-Enhanced Calibration Procedure For Multivariate Calibration Models With Near-Infrared Spectra, Mark R. Riley, Mark A. Arnold, David W. Murhammer Jan 1998

Matrix-Enhanced Calibration Procedure For Multivariate Calibration Models With Near-Infrared Spectra, Mark R. Riley, Mark A. Arnold, David W. Murhammer

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A novel method is introduced for developing calibration models for the spectroscopic measurement of chemical concentrations in an aqueous environment. To demonstrate this matrix-enhanced calibration procedure, we developed calibration models to quantitate glucose and glutamine concentrations in an insect cell culture medium that is a complex mixture of more than 20 components, with three components that manifest significant concentration changes. Accurate calibration models were generated for glucose and glutamine by using a calibration data set composed of 60 samples containing the analytes dissolved in an aqueous buffer along with as few as two samples of the analytes dissolved in culture …

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