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Articles 6661 - 6690 of 11222

Full-Text Articles in Engineering

Perchlorate Toxicity And Risk Assessment, David R. Mattie, Joan Strawson, Jay Zhao Jan 2006

Perchlorate Toxicity And Risk Assessment, David R. Mattie, Joan Strawson, Jay Zhao

United States Air Force: Publications

Ammonium perchlorate is the oxidizer ingredient in solid propellant mixtures for rockets, missiles and munitions such as Titan, Minuteman, Peacekeeper, Hawk, Polaris and the Space Shuttle. Perchlorate salts may also be used in medicine, matches, munitions and pyrotechnics (illuminating and signaling flares, colored and white smoke generators, tracers, incendiary delays, fuses, photo-flash compounds and fireworks). Perchlorate is also found in lubricating oils, finished leather, fabric fixer, dyes, electroplating, aluminum refining, manufacture of rubber, paint and enamel production, as an additive in cattle feed, in magnesium batteries and as a component of automobile air bag inflators.'

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Atomic Force Microscopy Of Bacillus Spore Surface Morphology, Ruth A. Zolock, Guangming Li, Charles Bleckmann, Larry Burggraf, Douglas C. Fuller Jan 2006

Atomic Force Microscopy Of Bacillus Spore Surface Morphology, Ruth A. Zolock, Guangming Li, Charles Bleckmann, Larry Burggraf, Douglas C. Fuller

United States Air Force: Publications

Bacillus spore surface morphology was imaged with atomic force microscopy (AFM) to determine if characteristic surface features could be used to distinguish between four closely related species; Bacillus anthracis Sterne strain, Bacillus thuringiensis var. kurstaki, Bacillus cereus strain 569, and Bacillus globigii var. niger. AFM surface height images showed an irregular topography across the curved upper surface of the spores. Phase images showed a superficial grain structure with different levels of phase contrast and significant differences in average surface morphologies among the four species. Although spores of the same species showed similarities, there was significant variability within each …

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Nanoparticle-Induced Negative Differential Resistance And Memory Effect In Polymer Bistable Light-Emitting Device, Ricky J. Tseng, Jianyong Ouyang, Chih-Wei Chu, Jinsong Huang, Yang Yang Jan 2006

Nanoparticle-Induced Negative Differential Resistance And Memory Effect In Polymer Bistable Light-Emitting Device, Ricky J. Tseng, Jianyong Ouyang, Chih-Wei Chu, Jinsong Huang, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Recently, electrical bistability was demonstrated in polymer thin films incorporated with metal nanoparticles [J. Ouyang, C. W. Chu, C. R. Szmanda, L. P. Ma, and Y. Yang, Nat. Mater. 3, 918 (2004)]. In this letter, we show the evidence that electrons are the dominant charge carriers in these bistable devices. Direct integration of bistable polymer layer with a light-emitting polymer layer shows a unique light-emitting property modulated by the electrical bistability. A unique negative differential resistance induced by the charged gold nanoparticles is observed due to the charge trapping effect from the nanoparticles when interfaced with the light-emitting layer.

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In Vivo Laparoscopic Robotics, Mark E. Rentschler, Stephen R. Platt, Jason Dumpert, Shane M. Farritor, Dmitry Oleynikov Jan 2006

In Vivo Laparoscopic Robotics, Mark E. Rentschler, Stephen R. Platt, Jason Dumpert, Shane M. Farritor, Dmitry Oleynikov

Department of Mechanical and Materials Engineering: Faculty Publications

Robotic laparoscopic surgery is evolving to include in vivo robotic assistants. The impetus for the development of this technology is to provide surgeons with additional viewpoints and unconstrained manipulators that improve safety and reduce patient trauma. A family of these robots have been developed to provide vision and task assistance. Fixed-base and mobile robots have been designed and tested in animal models with much success. A cholecystectomy, prostatectomy, and nephrectomy have all been performed with the assistance of these robots. These early successful tests show how in vivo laparoscopic robotics may be part of the next advancement in surgical technology.

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A Minimum-Impact Method For Measuring Corrosion Rate Of Steel-Hulled Shipwrecks In Seawater, Matthew A. Russell, David Conlin, Larry E. Murphy, Donald L. Johnson, Brent Wilson, James Carr Jan 2006

A Minimum-Impact Method For Measuring Corrosion Rate Of Steel-Hulled Shipwrecks In Seawater, Matthew A. Russell, David Conlin, Larry E. Murphy, Donald L. Johnson, Brent Wilson, James Carr

Department of Mechanical and Materials Engineering: Faculty Publications

Current research on USS Arizona is focused on a minimum-impact technique for calculating corrosion rate of the battleship’s steel hull by analyzing physical and chemical properties of marine encrustation covering the exposed hull. An equation is derived that allows concretion thickness, density, and total iron content to be used to calculate corrosion rate of steel hull plate.

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Comparative Modeling Of Performance Limits Of Solid State Neutron Detectors Based On Planar B-Rich Capture Layers, A. D. Harken, Brian W. Robertson Jan 2006

Comparative Modeling Of Performance Limits Of Solid State Neutron Detectors Based On Planar B-Rich Capture Layers, A. D. Harken, Brian W. Robertson

Department of Mechanical and Materials Engineering: Faculty Publications

Solid-state neutron detectors based only on boron-rich semiconductors are of interest for their potential to provide the highest thermal neutron detection efficiencies of any solid-state neutron detectors. A simple physical model, recently shown to generate thermal neutron capture product spectra that agree quantitatively with full-physics GEANT4 simulation, is used to compare the capture product energy spectra and the upper limits to neutron detection efficiency of planar conversion layer, sandwich and all-boron-carbide detectors for the case of normally incident, mono-energetic, thermal neutrons. All-boron-carbide semiconductor detectors are deduced to be greatly superior to all other boron-rich solid-state detector types in their maximal …

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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

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

United States Department of Energy: Publications

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

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Changes In Manganese And Lead In The Environment And Young Children Associated With The Introduction Of Methylcyclopentadienyl Manganese Tricarbonyl In Gasoline—Preliminary Results, Brian Gulson, Karen Mizon, Alan Taylor, Michael Korsch, Jennifer Stauber, J. Michael Davis, Honway Louis, Michael Wu, Hilton Swan Jan 2006

Changes In Manganese And Lead In The Environment And Young Children Associated With The Introduction Of Methylcyclopentadienyl Manganese Tricarbonyl In Gasoline—Preliminary Results, Brian Gulson, Karen Mizon, Alan Taylor, Michael Korsch, Jennifer Stauber, J. Michael Davis, Honway Louis, Michael Wu, Hilton Swan

United States Environmental Protection Agency: Publications

A 4-year longitudinal study is being conducted to evaluate potential changes to the environment and exposure of young children associated with the introduction of methylcyclopentadienyl manganese tricarbonyl (MMT) into Australia in 2001. The cohort consists of 57 females and 56 males, with an age range of 0.29–3.9 years. Samples are collected every 6 months from children in residences located at varying distances from major traffic thoroughfares in Sydney. Environmental samples include air, house, and daycare center dustfall, soil, dust sweepings, and gasoline; samples from the children include blood, urine, handwipes prior to and after playing outdoors, and a 6-day duplicate …

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Assessing Effects Of Alternative Agricultural Practices On Wildlife Habitat In Iowa, Usa, Mary Santelmann, Kathryn Freemark, Jean Sifneos, Denis White Jan 2006

Assessing Effects Of Alternative Agricultural Practices On Wildlife Habitat In Iowa, Usa, Mary Santelmann, Kathryn Freemark, Jean Sifneos, Denis White

United States Environmental Protection Agency: Publications

A habitat-change model was used to compare past, present, and future land cover and management practices to assess potential impacts of alternative agricultural practices on wildlife in two agricultural watersheds, Walnut Creek and Buck Creek, in central Iowa, USA. This approach required a habitat map for each scenario based on soil type and land cover, a list of resident species, and an estimate of the suitability of each of 26 habitat classes for every species. Impact on wildlife was calculated from median percent change in habitat area relative to the present. Habitat classes with the highest species richness for native …

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Inter-Habitat Variation In The Benthos Of The Upper Missouri River (North Dakota, Usa): Implications For Great River Bioassessment, Ted Angradi, E. William Schweiger, David Bolgrien Jan 2006

Inter-Habitat Variation In The Benthos Of The Upper Missouri River (North Dakota, Usa): Implications For Great River Bioassessment, Ted Angradi, E. William Schweiger, David Bolgrien

United States Environmental Protection Agency: Publications

We examined inter-habitat variation in benthic macroinvertebrate assemblages in the 180-km Garrison Reach of the Upper Missouri River, North Dakota (USA) in 2001–2003. The Garrison Reach is unchannelized with a mostly rural setting. Flows are regulated by Garrison Dam. We sampled benthos from three habitats defined a priori: channel, shoreline, and backwater. Benthic assemblages were different in each habitat. Average Bray-Curtis dissimilarity in assemblage composition ranged from 89% for backwater versus channel habitat to 70% for backwater versus shoreline habitat. There were distinct intra-habitat groups within a priori habitats: channel assemblages included moving-sand assemblages and other-substrate channel assemblages; backwater assemblages …

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Mode Of Action In Relevance Of Rodent Liver Tumors To Human Cancer Risk, Michael P. Holsapple, Henri C. Pitot, Samuel H. Cohen, Alan R. Boobis, James E. Klaunig, Timothy Pastoor, Vicki L. Dellarco, Yvonne P. Dragan Jan 2006

Mode Of Action In Relevance Of Rodent Liver Tumors To Human Cancer Risk, Michael P. Holsapple, Henri C. Pitot, Samuel H. Cohen, Alan R. Boobis, James E. Klaunig, Timothy Pastoor, Vicki L. Dellarco, Yvonne P. Dragan

United States Environmental Protection Agency: Publications

Hazard identification and risk assessment paradigms depend on the presumption of the similarity of rodents to humans, yet species specific responses, and the extrapolation of high-dose effects to lowdose exposures can affect the estimation of human risk from rodent data. As a consequence, a human relevance framework concept was developed by the International Programme on Chemical Safety (IPCS) and International Life Sciences Institute (ILSI) Risk Science Institute (RSI) with the central tenet being the identification of a mode of action (MOA). To perform a MOA analysis, the key biochemical, cellular, and molecular events need to first be established, and the …

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The Fathead Minnow In Aquatic Toxicology: Past, Present And Future, Gerald T. Ankley, Daniel L. Villeneuve Jan 2006

The Fathead Minnow In Aquatic Toxicology: Past, Present And Future, Gerald T. Ankley, Daniel L. Villeneuve

United States Environmental Protection Agency: Publications

This paper reviews the roles of the fathead minnow (Pimephales promelas) as a small fish model in the field of aquatic toxicology. The species has been (and is) extensively used both for regulatory testing and research, especially in North America. For example, tests with the fathead minnow, ranging from 48-h lethality through partial and full life-cycle assays, are routinely used for regulatory programs aimed at assessing potential risks of new chemicals such as high-production volume materials and pesticides, as well as impacts of complex mixtures like effluents. The species also has been used for a wide variety of …

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Isotope Sourcing Of Prehistoric Willow And Tule Textiles Recovered From Western Great Basin Rock Shelters And Caves: Proof Of Concept, Larry V. Benson, E. M. Hattori, H. E. Taylor, S. R. Poulson, E. A. Jolie Jan 2006

Isotope Sourcing Of Prehistoric Willow And Tule Textiles Recovered From Western Great Basin Rock Shelters And Caves: Proof Of Concept, Larry V. Benson, E. M. Hattori, H. E. Taylor, S. R. Poulson, E. A. Jolie

United States Geological Survey: Staff Publications

Isotope and trace-metal analyses were used to determine the origin of plants used to manufacture prehistoric textiles (basketry and matting) from archaeological sites in the western Great Basin. Research focused on strontium (87Sr/86Sr) and oxygen (18O/16O) isotope ratios of willow (Salix sp.) and tule (Schoenoplectus sp.), the dominant raw materials in Great Basin textiles. The oxygen-isotope data indicated that the willow and tule used to produce the textiles were harvested from the banks of rivers or in marshes characterized by flowing water and not from lakes or sinks. The strontium-isotope …

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Fast And Slow Magnetization Processes In Magnetic Recording Media, Jian Zhou, Ralph Skomski, Steven A. Michalski, Roger D. Kirby, David J. Sellmyer Jan 2006

Fast And Slow Magnetization Processes In Magnetic Recording Media, Jian Zhou, Ralph Skomski, Steven A. Michalski, Roger D. Kirby, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Information loss due to thermal activation is a major concern in ultrahigh-density magnetic recording media. The usually considered mechanism is thermally activated magnetization reversal over micromagnetic energy barriers. However, micromagnetic approaches ignore local anisotropy fluctuations, which translate into a time-dependent reduction of the remanent magnetization. The effect is negligibly small in macroscopic magnets but becomes important on a scale of a few nanometers.

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Spin-Polarized Electronic Structure, Arti Kashyap, Renat F. Sabirianov, Sitaram Jaswal Jan 2006

Spin-Polarized Electronic Structure, Arti Kashyap, Renat F. Sabirianov, Sitaram Jaswal

Materials Research Science and Engineering Center: Faculty Publications

This chapter is devoted to the electronic structure of nanoscale metallic magnets. After an introduction to methods of electronic structure calculations, we review how recent trends translate into the description of magnetic nanostructures. Among the considered structures are nanowires, small particles, surfaces and interfaces, and multilayers, and emphasis is on magnetic properties such as moment and magnetization, interatomic exchange, and anisotropy.

One of the goals of computational nanoscience is to calculate physical and chemical properties from first principles. This requires the knowledge of the electronic structures of the materials system in question. The density-functional theory (DFT) makes a huge step …

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"Introduction" To Advanced Magnetic Nanostructures, David J. Sellmyer, Ralph Skomski Jan 2006

"Introduction" To Advanced Magnetic Nanostructures, David J. Sellmyer, Ralph Skomski

Materials Research Science and Engineering Center: Faculty Publications

The nanostructures considered here are magnetic and characterized by structural length scales ranging from a few interatomic distances to about one micrometer. The basic length unit is the nanometer (1 nm = 10–3 μm = 10–9 m), corresponding to about four interatomic Fe-Fe distances. Magnetic nanostructures pose experimental challenges, exhibit interesting physical phenomena, and have many present or potential applications. An important aspect is that structural lengths affect, but only partly determine, the magnetic length scales encountered in the structures. Examples are domains in semihard nanoparticles, where both the domain size and the domain-wall thickness may be smaller …

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Human Transcriptome Corresponding To Human Oocytes And Use Of Said Genes Or The Corresponding Polypeptides To Trans-Differentiate Somatic Cells, Jose Bernardo Cibelli, Arif Murat Kocabas, Bing Lim, Hasan H. Otu Jan 2006

Human Transcriptome Corresponding To Human Oocytes And Use Of Said Genes Or The Corresponding Polypeptides To Trans-Differentiate Somatic Cells, Jose Bernardo Cibelli, Arif Murat Kocabas, Bing Lim, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

The identification of 101 genes upregulated or differentially expressed by mature human oocytes is provided herein. These genes and the corresponding gene products will facilitate a greater understanding of oogenesis, folliculogenesis, fertilization, and embryonic development. In addition these genes and the corresponding gene products can be used to effect dedifferentiation and/or transdifferentiation of desired somatic cells. The resultant dedifferentiated cells and somatic cells derived therefrom can be used in cell therapies such as in the treatment of cancer, autoimmunity, and other diseases wherein specific types of cells such as hematopoietic cells may be depleted because of the underlying disease or …

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Non-Operative Management Of Posterior Tibialis Tendon Dysfunction: Design Of A Randomized Clinical Trial [Nct00279630], Kornelia Kulig, Amy B. Pomrantz, Judith M. Burnfield, Stephen F. Reischl, Susan Mais-Requejo, David B. Thordarson, Ronald W. Smith Jan 2006

Non-Operative Management Of Posterior Tibialis Tendon Dysfunction: Design Of A Randomized Clinical Trial [Nct00279630], Kornelia Kulig, Amy B. Pomrantz, Judith M. Burnfield, Stephen F. Reischl, Susan Mais-Requejo, David B. Thordarson, Ronald W. Smith

Department of Mechanical and Materials Engineering: Faculty Publications

Background: Posterior tibialis tendon dysfunction (PTTD) is a common cause of foot pain and dysfunction in adults. Clinical observations strongly suggest that the condition is progressive. There are currently no controlled studies evaluating the effectiveness of exercise, orthoses, or orthoses and exercise on Stage I or IIA PTTD. Our study will explore the effectiveness of an eccentric versus concentric strengthening intervention to results obtained with the use of orthoses alone. Findings from this study will guide the development of more efficacious PTTD intervention programs and contribute to enhanced function and quality of life in persons with posterior tibialis tendon dysfunction. …

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Complex Orthogonal Spreading Sequences Using Mutually Orthagonal Complimentary Sets, Ying Zhao, Jennifer Seberry, Beata J. Wysocki, Tadeusz Wysocki Jan 2006

Complex Orthogonal Spreading Sequences Using Mutually Orthagonal Complimentary Sets, Ying Zhao, Jennifer Seberry, Beata J. Wysocki, Tadeusz Wysocki

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

This paper presents a new family of complex spreading sequences designed using mutually orthogonal(MO) complementary sets. Based on the technique described in this paper, the correlation properties of sets of sequences are compared to well-known Walsh-Hadamard sequence sets. Further improvement of correlation qualities can be achieved by employing a diagonal modification method. We also present simulation results of an asynchronous multiuser CDMA system using the modified sequences.

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