Engineering Commons^™

Role Of Branching On The Structure Of Polymer Brushes Formed From Comb Copolymers, Peng Tian, David Uhrig, Jimmy W. Mays, Hiroshi Watanabe, S. Michael Kilbey, Ii

United States Department of Energy: Publications

The distinguishing feature of a polymer brush at equilibrium is the stretched configuration of the chains that results from tethering the polymer chains by one end at the solid-fluid interface. The stretched configuration of the chains and the crowded nature of the interfacial layer is the origin of many of the useful properties of polymer brushes: these layers resist compression and aggregation, effectively dissipate shear stresses, and respond reversibly to changes in their solution environment.

Maldi-Tof Ms Characterization Of Carboxyl-End-Capped Polystyrenes Synthesized Using Anionic Polymerization, Haining Ji, William K. Nonidez, Rigoberto C. Advincula, Grant D. Smith, S. Michael Kilbey Ii, Mark D. Dadmun, Jimmy W. Mays

United States Department of Energy: Publications

A comparative study of three strategies used to synthesize well-defined carboxyl-end-capped polystyrenes is reported. Structural characterization was carried out using a combination of thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). For the reaction of polystyryl anions with 4-bromo-1,1,1-trimethoxybutane, in addition to the major product, Bu-PS-CH₂CH₂CH₂COOH, four byproducts were observed. Their mass values suggest the following structures: Bu-PS-H, Bu-PS-CH₃, Bu-PS-CH₂CH=CH-CHO, and Bu-PS-CH₂CH₂CH₂- CO-PS-Bu. The reaction of polystyryl anions with succinic anhydride generated the targeted compound, Bu-PS-CO-CH₂CH₂COOH, …

Ferrous Hydroxy Carbonate Is A Stable Transformation Product Of Biogenic Magnetite, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, David W. Kennedy, Alice C. Dohnalkova, David E. Mccready

United States Department of Energy: Publications

An ~1:1 mixture of ferrihydrite and nanocrystalline akaganeite (β-FeOOH; 10–15 nm) was incubated with Shewanella putrefaciens (strain CN32) under anoxic conditions with lactate as an electron donor and anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle. The incubation was carried out in a 1,4-piperazinediethanesulfonic acid (PIPES)-buffered medium, without PO³₄– at circumneutral pH. Iron reduction was measured as a function of time (as determined by 0.5 N HCl extraction), and solids were characterized by X-ray diffraction (XRD), electron microscopy, and Mössbauer spectroscopy. The biogenic reduction of Fe³⁺was rapid; with 60% of the total Fe (Fe_TOT) reduced …

Control Of Fe(Iii) Site Occupancy On The Rate And Extent Of Microbial Reduction Of Fe(Iii) In Nontronite, Deb P. Jaisi, Ravi K. Kukkadapu, Dennis D. Eberl, Hailiang Dong

United States Department of Energy: Publications

A quantitative study was performed to understand how Fe(III) site occupancy controls Fe(III) bioreduction in nontronite by Shewanella putrefaciens CN32. NAu-1 and NAu-2 were nontronites and contained Fe(III) in different structural sites with 16 and 23% total iron (w/w), respectively, with almost all iron as Fe(III). Mössbauer spectroscopy showed that Fe(III) was present in the octahedral site in NAu-1 (with a small amount of goethite), but in both the tetrahedral and the octahedral sites in NAu-2. Mössbauer data further showed that the octahedral Fe(III) in NAu-2 existed in at least two environments- trans (M1) and cis (M2) sites. The microbial …

Effects Of Sediment Iron Mineral Composition On Microbially Mediated Changes In Divalent Metal Speciation: Importance Of Ferrihydrite, D. Craig Cooper, Andrew L. Neal, Ravi K. Kukkadapu, Dale Brewe, Aaron Coby, Flynn W. Picardal

United States Department of Energy: Publications

Dissimilatory metal reducing bacteria (DMRB) can influence geochemical processes that affect the speciation and mobility of metallic contaminants within natural environments. Most investigations into the effect of DMRB on sediment geochemistry utilize various synthetic oxides as the Fe^III source (e.g., ferrihydrite, goethite, hematite). These synthetic materials do not represent the mineralogical composition of natural systems, and do not account for the effect of sediment mineral composition on microbially mediated processes. Our experiments with a DMRB (Shewanella putrefaciens 200) and a divalent metal (Zn^II) indicate that, while complexity in sediment mineral composition may not strongly impact the …

Development Of High-Temperature Ferromagnetism In Sno2 And Paramagnetism In Sno By Fe Doping, A. Punnoose, J. Hays, A. Thurber, M. H. Engelhard, Ravi K. Kukkadapu, C. Wang, V. Shutthanandan, S. Thevuthasan

United States Department of Energy: Publications

We report the development of room-temperature ferromagnetism in chemically synthesized powder samples of Sn_1−xFe_xO₂ (0.005≤ x ≤0.05) and paramagnetic behavior in an identically synthesized set of Sn_1−xFe_xO. The ferromagnetic Sn_0.99Fe_0.01O₂ showed a Curie temperature T_C=850 K, which is among the highest reported for transition-metal-doped semiconductor oxides. With increasing Fe doping, the lattice parameters of SnO₂ decreased and the saturation magnetization increased, suggesting a strong structure-magnetic property relationship. When the Sn_0.95Fe_0.05O₂ was prepared at different temperatures between …

Influence Of Calcite And Dissolved Calcium On Uranium(Vi) Sorption To A Hanford Subsurface Sediment, Wenming Dong, William Ball, Chongxuan Liu, Zheming Wang, Alan Stone, Jing Bai, John M. Zachara

United States Department of Energy: Publications

The influence of calcite and dissolved calcium on U(VI) adsorption was investigated using a calcite-containing sandy silt/clay sediment from the U. S. Department of Energy Hanford site. U(VI) adsorption to sediment, treated sediment, and sediment size fractions was studied in solutions that both had and had not been preequilibrated with calcite, at initial [U(VI)] ) 10^-7-10^-5 mol/L and final pH ) 6.0- 10.0. Kinetic and reversibility studies (pH 8.4) showed rapid sorption (30 min), with reasonable reversibility in the 3-day reaction time. Sorption from solutions equilibrated with calcite showed maximum U(VI) adsorption at pH 8.4 ± 0.1. …

Influence Of Sediment Bioreduction And Reoxidation On Uranium Sorption, Chongxuan Liu, John M. Zachara, Lirong Zhong, Ravi K. Kukkadapu, Jim Szecsody, Dave Kennedy

United States Department of Energy: Publications

The influence of sediment bioreduction and reoxidation on U(VI) sorption was studied using Fe(III) oxide-containing saprolite from the U.S. Department of Energy (DOE) Oak Ridge site. Bioreduced sediments were generated by anoxic incubation with a metal-reducing bacterium, Shewanella putrefaciens strain CN32, supplied with lactate as an electron donor. The reduced sediments were subsequently reoxidized by air contact. U(VI) sorption was studied in Na- NO₃-HCO₃ electrolytes that were both closed and open to atmosphere and where pH, U(VI), and carbonate concentration were varied. Mössbauer spectroscopy and chemical analyses showed that 50% of the Fe(III)- oxides were reduced to …

Fluorescence Spectroscopy Of U(Vi)-Silicates And U(Vi)-Contaminated Hanford Sediment, Zheming Wang, John M. Zachara, Paul Gassman, Chongxuan Liu, Odeta Qafoku, Wassana Yantasee, Jeff Catalano

United States Department of Energy: Publications

Time-resolved U(VI) laser fluorescence spectra (TRLFS) were recorded for a series of natural uranium-silicate minerals including boltwoodite, uranophane, soddyite, kasolite, sklodowskite, cuprosklodowskite, haiweeite, and weeksite, a synthetic boltwoodite, and four U(VI)-contaminated Hanford vadose zone sediments. Lowering the sample temperature from RT to ~5.5 K significantly enhanced the fluorescence intensity and spectral resolution of both the minerals and sediments, offering improved possibilities for identifying uranyl species in environmental samples. At 5.5 K, all of the uranyl silicates showed unique, well-resolved fluorescence spectra. The symmetric O = U = O stretching frequency, as determined from the peak spacing of the vibronic bands …

Oxidative Remobilization Of Biogenic Uranium(Iv) Precipitates: Effects Of Iron(Ii) And Ph, Lirong Zhong, Chongxuan Liu, John M. Zachara, David Kennedy, James E. Szecsody, Brian Wood

United States Department of Energy: Publications

The oxidative remobilization of uranium from biogenic U(IV) precipitates was investigated in bioreduced sediment suspensions in contact with atmospheric O2 with an emphasis on the influence of Fe(II) and pH on the rate and extent of U release from the solid to the aqueous phase. The sediment was collected from the U.S. Department of Energy Field Research Center (FRC) site at Oak Ridge, Tennessee. Biogenic U(IV) precipitates and bioreduced sediment were generated through anaerobic incubation with a dissimilatory metal reducing bacterium Shewanella putrefaciens strain CN32. The oxidative remobilization of freshly prepared and 1-yr aged biogenic U(IV) was conducted in 0.1 …

Enzymology Of Electron Transport: Energy Generation With Geochemical Consequences, Thomas J. Dichristina, James K. Fredrickson, John M. Zachara

United States Department of Energy: Publications

Dissimilatory metal-reducing bacteria (DMRB) are important components of the microbial community residing in redox-stratified freshwater and marine environments. DMRB occupy a central position in the biogeochemical cycles of metals, metalloids and radionuclides, and serve as catalysts for a variety of other environmentally important processes including biomineralization, biocorrosion, bioremediation and mediators of ground water quality. DMRB are presented, however, with a unique physiological challenge: they are required to respire anaerobically on terminal electron acceptors which are either highly insoluble (e.g., Fe(III)- and Mn(IV)-oxides) and reduced to soluble end-products or highly soluble (e.g., U(VI) and Tc(VII)) and reduced to insoluble end-products. To …

Photoionization And Electron-Impact Ionization Of Xe3+, E. D. Emmons, A. Aguilar, M. F. Gharaibeh, S. W. J. Scully, R. A. Phaneuf, A. L. D. Kilcoyne, A. S. Schlachter, I. Álvarez, C. Cisneros, G. Hinojosa

United States Department of Energy: Publications

Photoionization and electron-impact ionization of Xe³⁺ ions in the region of 4d inner-shell excitation autoionization have been studied using interacting-beam spectroscopic techniques. Absolute cross sections for photoionization of Xe³⁺ have been obtained and the electron-impact spectrum has been normalized to previously published absolute data. The Xe³⁺ spectra show large contributions from 4d→nf excitation autoionization processes compared to the lower charge states of Xe due to the significant collapse of the nf wave functions into the ion core as the initial charge state of the ion is increased. In addition, a tentative value for …

Chemical Mapping Of Polymer Photoresists By Scanning Transmission X-Ray Microscopy, Ligia Muntean, Romain Planques, A. L. D. Kilcoyne, Stephen R. Leone, Mary Gilles, William D. Hinsberg

United States Department of Energy: Publications

Scanning transmission x-ray microscopy (STXM) is shown to be a powerful imaging technique that provides chemical selectivity and high spatial resolution (~35 nm) for studying chemically amplified photoresists. Samples of poly (4-t-butoxycarbonyloxystyrene) PTBOCST resist, imprinted by deep ultraviolet lithography with a line/space pattern of 1.10 μm/ 0.87 μm followed by a post-exposure bake, are used to demonstrate STXM imaging capabilities to extract photoresist latent images. Chemical contrast is obtained by measuring the x-ray absorption at an energy of 290.5 eV, corresponding to a carbon K shell electronic transition to the unoccupied π^* molecular orbital of the PTBOCST …

Photoionization Of Multiply Charged Ions At The Advanced Light Source, A. S. Schlachter, A. L. D. Kilcoyne, A. Aguilar, M. F. Gharaibeh, E. D. Emmons, S. W. J. Scully, R. A. Phaneuf, A. M. Müller, S. Schippers, I. Alvarez, C. Cisneros, G. Hinojosa, B. M. Mclaughlin

United States Department of Energy: Publications

Photoionization of multiply charged ions is studied using the merged-beams technique at the Advanced Light Source. An ion beam is created using a compact 10-GHz all-permanent-magnet ECR ion source and is accelerated with a small accelerator. The ion beam is merged with a photon beam from an undulator to allow interaction over an extended path. Absolute photoionization cross sections have been measured for a variety of ions along both isoelectronic and isonuclear sequences.

Photoexcitation Of A Volume Plasmon In C60 Ions, S. W. J. Scully, E. D. Emmons, M. F. Gharaibeh, R. A. Phaneuf, A. L. D. Kilcoyne, A. S. Schlachter, S. Schippers, A. M. Müller, H. S. Chakraborty, M. E. Madjet, J. M. Rost

United States Department of Energy: Publications

Neutral C₆₀ is well known to exhibit a giant resonance in its photon absorption spectrum near 20 eV. This is associated with a surface plasmon, where delocalized electrons oscillate as a whole relative to the ionic cage. Absolute photoionization cross-section measurements for C⁺₆₀, C²⁺₆₀, and C³⁺₆₀ ions in the 17– 75 eV energy range show an additional resonance near 40 eV. Time-dependent density functional calculations confirm the collective nature of this feature, which is characterized as a dipole-excited volume plasmon made possible by the special fullerene geometry.

Potential Of Multivariate Quantitative Methods For Delineation And Visualization Of Ecoregions, William Hargrove, Forrest Hoffman

United States Department of Energy: Publications

Multivariate clustering based on fine spatial resolution maps of elevation, temperature, precipitation, soil characteristics, and solar inputs has been used at several specified levels of division to produce a spectrum of quantitative ecoregion maps for the conterminous United States. The coarse ecoregion divisions accurately capture intuitively-understood regional environmental differences, whereas the finer divisions highlight local condition gradients, ecotones, and clines. Such statistically generated ecoregions can be produced based on user-selected continuous variables, allowing customized regions to be delineated for any specific problem. By creating an objective ecoregion classification, the ecoregion concept is removed from the limitations of human subjectivity, making …

Carbon Nanotubes With Covalently Linked Porphyrin Antennae: Photoinduced Electron Transfer, Durairaj Baskaran, Jimmy W. Mays, X. Peter Zhang, Matthew S. Bratcher

United States Department of Energy: Publications

Functionalization of carbon nanotubes through surface modification has attracted significant interest recently. Covalent and noncovalent functionalization strategies involving reactions of organic or polymeric molecules onto carbon nanotubes have primarily focused on dispersion or dissolution properties. Incorporation of light absorbing antenna chromophores through a covalent linkage with the extended π electrons of a carbon nanotube would constitute an ideal supramolecular nanoassembly for generating singlet excited energy and its conversion to chemical energy. Porphyrins are one such class of molecules used in assemblies of donor-acceptor materials in molecular electronics and photovoltaic devices.

Several fullerene-based molecular systems with covalently linked porphyrins and metalloporphyrins …

Noncovalent And Nonspecific Molecular Interactions Of Polymers With Multiwalled Carbon Nanotubes, Durairaj Baskaran, Jimmy W. Mays, Matthew S. Bratcher

United States Department of Energy: Publications

Polymer composites containing variable amounts of multiwalled carbon nanotubes (MWNTs) have been prepared using solution dispersion and melt-shear mixing. Various polymer composites with 1 wt % MWNTs have been found to dissolve homogeneously in organic solvents. The amount of polymer coated or wrapped MWNTs dissolved in the solution was quantified using UV-vis absorbance at 500 nm and the concentration ratio of [MWNTs]_solution/[MWNTs]_composite was close to 1. A nonspecific polymer adsorption through multiple-weak molecular interactions of CH groups with MWNTs in the composites has been identified through FTIR spectroscopy. The composites of polybutadiene with different wt % of …

Relationship Of Stream Flow Regime In The Western Lake Superior Basin To Watershed Type Characteristics, N. E. Detenbeck, V. J. Brady, D. L. Taylor, V. M. Snarski, S. L. Batterman

United States Environmental Protection Agency: Publications

To test a conceptual model of non-linear response of hydrologic regimes to watershed characteristics, we selected 48 secondand third-order study sites on the North and South Shores of western Lake Superior, MN(USA) using a random-stratified design based on hydrogeomorphic region, fraction mature forest, and fraction watershed storage (lakeCwetland area/watershed area). We calculated several commonly used hydrologic indices from discharge and velocity estimates, including daily flow indices, overall flood indices, low flow variables, and ratios or ranges of flow percentiles reflecting the nature of cumulative frequency distributions. Four principal components (PCs) explained 85.9 and 88.6% of the variation of flow metrics …

Regional Scale Evidence For Improvements In Surface Water Chemistry 1990-2001, B. L. Skjelkvåle, J. L. Stoddard, D. S. Jeffries, K. Tørseth, T. Høgåsen, J. Bowman, J. Mannio, D. T. Monteith, R. Mosello, M. Rogora, D. Rzychon, J. Vesely, J. Wieting, A. Wilander, A. Worsztynowicz

United States Environmental Protection Agency: Publications

The main aim of the international UNECE monitoring program ICP Waters under the Convention of Long-range Transboundary Air Pollution (CLRTAP) is to assess, on a regional basis, the degree and geographical extent of the impact of atmospheric pollution, in particular acidification, on surface waters. Regional trends are calculated for 12 geographical regions in Europe and North America, comprising 189 surface waters sites. From 1990-2001 sulphate concentrations decreased in all but one of the investigated regions. Nitrate increased in only one region, and decreased in three North American regions. Improvements in alkalinity and pH are widely observed. Results from the ICP …

Test 1866: John Deere 5225 Diesel 9-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

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

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Nebraska Summary 572: Case-Ih Jx1095c Diesel 12-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

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

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1860: Challenger Mt835b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Preconditioning Of Primary Human Endothelial Cells With Inflammatory Mediators Alters The “Set Point” Of The Cell, Youichiro Wada, Hasan H. Otu, Shengqian Wu, Md. Ruhul Abid, Hitomi Okada, Towia Libermann, Tatsuhiko Kodama, Shu-Ching Shih, Takashi Minami, William C. Aird

Department of Electrical and Computer Engineering: Faculty Publications

Endothelial cells are highly sensitive to changes in the extracellular milieu. Sepsis results in activation of inflammatory and coagulation pathways. We hypothesized that sepsis-associated mediators may alter the response capacity (so-called “set point”) of endothelial cells. Human umbilical vein endothelial cells (HUVEC) were preincubated in the presence or absence of tumor necrosis factor (TNF)-α, lipopolysaccharide (LPS), hypoxia, hyperthermia, and/or high glucose; treated with or without thrombin for 4 h; and then processed for RNase protection assays of selected activation markers. Priming with TNF-α and LPS significantly inhibited thrombin-mediated induction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, tissue factor, and …

Performance Of Convolutional Interleavers With Different Spacing Parameters In Turbo Codes, Sina Vafi, Tadeusz Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

This paper considers application of a convolutional interleaver and the issue of infuence of the space parameter in the turbo code performance. Similarly to previously considered convolutional interleavers, the new interleavers are designed as block interleavers and their performance in different code structures is compared with the interleaver having higher periods and space value of 1. In each comparison, the number of inserted stuff bits at the end of each data block is considered to be of similar order. Finally, suitable modification to the new interleavers is proposed improving performance for the codes with lower number of stuff bits.

Preparation And Evaluation Of The Electrospun Chitosan/Peo Fibers For Potential Applications In Cartilage Tissue Engineering, Anuradha Subramanian, David Vu, Gustavo F. Larsen, Hsin Yii Lin

Papers in Biotechnology

Fibrous materials have morphological similarities to natural cartilage extracellular matrix and have been considered as candidate for bone tissue engineering scaffolds. In this study, we have evaluated a novel electrospun chitosan mat composed of oriented sub-micron fibers for its tensile property and biocompatibility with chondrocytes (cell attachment, proliferation and viability). Scanning electronic microscope images showed the fibers in the electrospun chitosan mats were indeed aligned and there was a slight cross-linking between the parent fibers. The electrospun mats have significantly higher elastic modulus (2.25 MPa) than the cast films (1.19 MPa). Viability of cells on the electrospun mat was 69% …

Technical Chair’S Message, A. Beghdadi, Tadeusz Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

We have organized an exciting technical program which includes tutorials, plenary sessions, and technical presentations. All technical submissions to the conference were based on full-length papers. Each paper has been assessed by at least two reviewers. This year marks the first time that a double-blind peer review process has been used in an ISSPA conference. Overall, the process was a great success with both authors and reviewers conforming to the double-blind review guidelines. We received 395 paper submissions, most of which were of very high quality. However, due to space limitations, only 228 articles were accepted for presentation at the …

Self-Assembly Of Nanoparticles On Live Bacterium: An Avenue To Fabricate Electronic Devices, Vikas Berry, Ravi F. Saraf

Ravi Saraf Publications

Lysine-capped gold nanoparticles can be electrostatically assembled on the surface of Bacillus cerius, a Gram-Positive bacterium. The conductivity of the “gold-plated” bacteria assembly immobilized between electrodes is a function of the humidity experienced by the nanoparticles.

Observations Of The Small-Scale Variability Of Precipitation Using An Imaging Radar, Robert D. Palmer, Boon Leng Cheong, Michael Hoffman, Stephen J. Frasier, F.J. Lopez-Dekker

Department of Electrical and Computer Engineering: Faculty Publications

For many years, spatial and temporal inhomogeneities in precipitation fields have been studied using scanning radars, cloud radars, and disdrometers, for example. Each measurement technique has its own advantages and disadvantages. Conventional profiling radars point vertically and collect data while the atmosphere advects across the field of view. Invoking Taylor’s frozen turbulence hypothesis, it is possible to construct time-history data, which are used to study the structure and dynamics of the atmosphere. In the present work, coherent radar imaging is used to estimate the true three-dimensional structure of the atmosphere within the field of view of the radar. The 915-MHz …

The U.S. Air Force Remotely Piloted Aircraft And Unmanned Aerial Vehicle Strategic Vision, U.S. Air Force

United States Air Force: Publications

The U.S. Air Force Remotely Piloted Aircraft and Unmanned Aerial Vehicle Strategic Vision (hereafter referred to as The Strategic Vision) examines the future role of Air Force remotely piloted aircraft (RPAs) and unmanned aerial vehicles (UAVs) and their integration with other Air Force and joint systems. The Strategic Vision is presented in five sections.