Physical Sciences and Mathematics Commons^™

Low Temperature Ordering And High (001) Orientation Of [Fe/Pt/Cu]18 Multilayer Films, Yongsheng Yu, Xingzhong Li, T A. George, W D. Fei, Haibo Li, David J. Sellmyer

David Sellmyer Publications

[Fe/Pt/Cu]₁₈ multilayer films with different Cu thicknesses were prepared on thermally oxidized Si (111) substrates at room temperature using dc- and rf-magnetron sputtering. The magnetic proper-ties and microstructure of [Fe/Pt/Cu]₁₈ multilayer films annealed at various temperatures have been investigated. Compared with pure [Fe/Pt]₁₈ multilayer films low-temperature ordering and (001) ori-entation in the annealed films with Cu volume concentration below 20% can be obtained. During annealing process Cu atoms diffused into FePt lattice which enhanced the diffusion of Fe and Pt atoms and the grain growth of the films. The perpendicular anisotropy and hard magnetic properties of the …

Effect Of Exchange Interactions On The Coercivity Of Smco5 Nanoparticles Made By Cluster Beam Deposition, O Akdogan, W Li, B Balasubrmanian, David J. Sellmyer, George C. Hadjipanayis

David Sellmyer Publications

Single crystal SmCo₅ nanoparticles with an average size of 3.5 nm are produced by cluster-beam deposition. When deposited without matrix, the nanoparticles showed a super-paramagnetic be-havior with a blocking temperature of 145 K. Dispersion of the SmCo₅ nanoparticles in a carbon matrix results in an increase in both the coercivity and the blocking temperature. Room temperature coercivities as high as 12 kOe are obtained for the first time in mono-layers of SmCo₅ nanoparticles dispersed in C matrix. δM plots show that the interactions in the samples are of exchange type, which can decrease the overall effective …

Novel Nanostructured Rare-Earth-Free Magnetic Materials With High Energy Products, Balamurugan Balasubramanian, Bhaskar Das, Ralph Skomski, Wenyong Zhang, David J. Sellmyer

David Sellmyer Publications

The development of new iron- or cobalt-rich permanent-magnet materials is of paramount importance in materials science and technology since high-performance materials based on Nd₂Fe₁₄B or FePt are extremely expensive or subject to limited rare-earth supplies.^[1–4] Aside from phase-diagram considerations, this requires alloys with high magnetocrystal-line anisotropy K1 and Curie temperature Tc. However, the range of alternative compounds with appreciable K1 and high Tc is limited, and the situation is often aggravated by their metastable nature and by the requirement of high-formation temperatures.^[5–12] For exam-ple, two suitable candidates are Zr₂Co₁₁ and HfCo …

Solubility Extension And Phase Formation In Gas-Condensed Co–W Nanoclusters, Farhad Golkar, Matthew J. Kramer, Ames Laboratory, Ralph A. Skomski, David J. Sellmyer, Jeffrey E. Shield

David Sellmyer Publications

Co–W alloy clusters with extended solubility of W in hcp Co were produced by inert-gas condensa-tion. The structural state of the as-deposited Co–W clusters was found to be critically dependent on processing parameters such as the cooling scheme and sputtering power. For the water-cooled clus-ters, the mean size and percent crystalline were strongly dependent on sputtering power, while the percent crystalline of the liquid nitrogen-cooled clusters was not as affected by the sputtering power. At low sputtering powers, the water-cooled clusters were predominantly amorphous, but became increasingly more crystalline as the sputtering power increased. The predominant crystalline phase was hcp …

Magnetism Of Rapidly Quenched Rhombohedral Zr2Co11-Based Nanocomposites, Wenyong Zhang, Xingzhong Li, Shah R. Valloppilly, Ralph A. Skomski, Jeffrey E. Shield, David J. Sellmyer

David Sellmyer Publications

The effect of quench rate and Zr content on nanostructure and magnetic properties of melt-spun Zr_xCo_100−x (x = 16–21) is investigated. High quench rate favors the formation of rhombohedral Zr₂Co₁₁, which is the hard phase. The coercivity increases with an increase in quench rate. Zr addition in limited amounts decreases the grain size of magnetic phases, which may promote the effective ex-change coupling of soft magnetic phases. Therefore, coercivity and maximum energy product of Zr₂Co₁₁-based materials are significantly enhanced. The best magnetic properties, iHc = 3.0 kOe and (BH) …

One-Pot Synthesis Of Urchin-Like Fepd−Fe3O4 And Their Conversion Into Exchange-Coupled L10−Fepd−Fe Nanocomposite Magnets, Yongsheng Yu, Kewei Sun, Yuan Tian, Xingzhong Li, Matthew J. Kramer, David J. Sellmyer, Jeffrey E. Shield, Shouheng Sun

David Sellmyer Publications

We report a one-pot synthesis of urchin-like FePd−Fe₃O₄ nanocomposites, spherical clusters of FePd nanoparticles (NPs) with spikes of Fe₃O₄ nanorods (NRs), via controlled thermal decomposition of Fe(CO)₅ and reduction of Pd(acac)₂. The FePd NPs with sizes between 6 and 9 nm self-aggregate into 60 nm superparticles (SPs), and Fe₃O₄ NRs grow on the surface of these SPs. Reductive annealing at 500°C converts the FePd−Fe₃O₄ into exchange-coupled nanocomposites L1₀−FePd−Fe with their Hc tunable from 0.8 to 2.6 kOe and Ms controlled from 90 to …

Threshold Alignment Reversal And Circularly Polarized Fluorescence In Rotationally Resolved H2, Jack W. Maseberg, Klaus Bartschat, Timothy J. Gay

Timothy J. Gay Publications

Using H₂ and D₂ targets, we have measured the polarization of Fulcher-band fluorescence resulting from spin-polarized electron-impact excitation of vibrationally and rotationally resolved d ³Π_u→ a ³ ∑_g⁺ transitions for incident electron energies from 14.3 to 28.5 eV. Near threshold, the linear polarization P₁ descends from positive values through zero to negative values, indicating a dynamic production of M_N = 0 states. The circular polarization P₃ is measured to be nonzero, indicating the orientation of rotationally resolved molecular states. For Q-branch transitions, P₃ is consistent with theory based …

Optically Pumped Spin-Exchange Polarized-Electron Source, Munir Pirbhai, J. Knepper, E. T. Litaker, D. Tupa, Timothy J. Gay

Timothy J. Gay Publications

We describe the operation of a prototype polarized-electron source. Rubidium vapor, contained in a cell, is optically pumped in the presence of a buffer gas. Unpolarized electrons from a tungsten filament are injected into the cell and extracted after undergoing spin exchange with the Rb atoms. We compare the performance of the source when different buffer gases are used. We measure a decrease in electron polarization as their injection energy increases, but find an unexpected regime at higher injection energies yielding increased electron polarization accompanied by a 40-fold increase in current, suggesting the production of slow secondary electrons in the …

Two Novel Approaches For Electron Beam Polarization From Unstrained Gaas, James L. Mccarter, Nathan B. Clayburn, J. M. Dreiling, Timothy J. Gay, Dominic M. Ryan, John Hansknecht, Matt Poelker, Andrei Afanasev, Ara Kechiantz

Timothy J. Gay Publications

Two novel approaches to producing highly-polarized electron beams from unstrained GaAs were tested using a micro-Mott polarimeter. Based on a suggestion by Nakanishi [1]], twophoton photoemission with 1560 nm light was used with photocathodes of varying thickness: 625m, 0.32m, and 0.18m. For each of these photocathodes, the degree of spin polarization of the photoemitted beam was less than 50%. Polarization via two-photon absorption was highest from the thinnest photocathode sample and close to that obtained from one-photon absorption (using 778 nm light), with values 40.3±1.0% and 42.6±1.0%, respectively. The second attempt to produce highly-polarized electrons used one-photon emission with 778 …

Face-To-Data -- Another Developing Privacy Threat?, Fred H. Cate, Christopher Kuner, Christopher Millard, Dan Jerker B. Svantesson

Articles by Maurer Faculty

No abstract provided.

Prism And Privacy: Will This Change Everything?, Fred H. Cate, Christopher Kuner, Christopher Millard, Dan Jerker B. Svantesson

Articles by Maurer Faculty

No abstract provided.

The Extraterritoriality Of Data Privacy Laws -- An Explosive Issue Yet To Detonate, Fred H. Cate, Christopher Kuner, Christopher Millard, Dan Jerker B. Svantesson

Articles by Maurer Faculty

No abstract provided.

Notice And Consent In A World Of Big Data, Fred H. Cate, Viktor Mayer-Schönberger

Articles by Maurer Faculty

• Nowadays individuals are often presented with long and complex privacy notices routinely written by lawyers for lawyers, and are then requested to either ‘consent’ or abandon the use of the desired service.
• The over-use of notice and consent presents increasing challenges in an age of ‘Big Data’.
• These phenomena are receiving attention particularly in the context of the current review of the OECD Privacy Guidelines.
• In 2012 Microsoft sponsored an initiative designed to engage leading regulators, industry executives, public interest advocates, and academic experts in frank discussions about the role of individual control and notice and consent in data protection …

Fea Estimation And Experimental Validation Of Solid Rotor And Magnet Eddy Current Loss In Single-Sided Axial Flux Permanent Magnet Machines, Xu Yang, Dean Patterson, Jerry Hudgins, Jessica Colton

Department of Electrical and Computer Engineering: Faculty Publications

The rotor and magnet loss in single-sided axial flux permanent magnet machines with non-overlapped windings is studied in this paper. FEA estimations of the loss are carried out using both 2-D and 3-D modeling. The rotor and magnet losses are determined separately for stator slot passing and MMF space harmonics from currents in the stator. The segregation of loss between the solid rotor plate and the magnet is addressed. The eddy current loss reduction by magnet segments is discussed as well. The prototype 24 slot/22 pole single-sided AFPMs, fabricated with both single layer and double layer windings are assembled. Methods …

Porous Polymer Coatings As Substrates For The Formation Of High-Fidelity Micropatterns By Quill-Like Pens, Michael Hirtz, Marcus Lyon, Wenqian Feng, Andrea E. Holmes, Harald Fuchs, Pavel A. Levkin

Department of Chemistry: Faculty Publications

We explored the potentials of microarray printing using quill-like microcantilevers onto solid supports that are typically used in microspot printing, including paper, polymeric nitrocellulose and nylon membranes. We compared these membranes with a novel porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) support (HEMA) with narrow pore size distribution in the 150 nm range, which demonstrated advantages in pattern definition, spot homogeneity, and consistent spot delivery of different dyes (phloxine B and bromophenol blue) with diameters of several micrometres. The bromophenol blue arrays on HEMA support were used to detect the presence of bovine serum albumin (BSA). In the presence of BSA, …

Single Transcriptional And Translational Preq1 Riboswitches Adopt Similar Pre-Folded Ensembles That Follow Distinct Folding Pathways Into The Same Ligand-Bound Structure, Krishna C. Suddala, Arlie J. Rinaldi, Jun Feng, Anthony M. Mustoe, Catherine D. Eichhorn, Joseph A. Liberman, Joseph E. Wedekind, Hashim M. Al-Hashimi, Charles L. Brooks Iii, Nils G. Walter

Department of Chemistry: Faculty Publications

Riboswitches are structural elements in the 50 untranslated regions of many bacterial messenger RNAs that regulate gene expression in response to changing metabolite concentrations by inhibition of either transcription or translation initiation. The preQ₁ (7-aminomethyl-7-deazaguanine) riboswitch family comprises some of the smallest metabolite sensing RNAs found in nature. Once ligand-bound, the transcriptional Bacillus subtilis and translational Thermoanaerobacter tengcongensis preQ₁ riboswitch aptamers are structurally similar RNA pseudoknots; yet, prior structural studies have characterized their ligand-free conformations as largely unfolded and folded, respectively. In contrast, through single molecule observation, we now show that, at nearphysiological Mg²⁺ concentration and pH, …

Iodonium Cyclophanes For Secure Arene Functionalization, Stephen Dimagno

Department of Chemistry: Faculty Publications

This disclosure relates to compounds, reagents, and methods useful in the synthesis of aryl fluorides, for example, in the preparation of 18F labeled radiotracers. For example, this disclosure provides universal “locked” aryl substituents that result in StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) from diaryliodonium salts. The reagents and methods provided herein may be used to access a broad range of compounds, including aromatic compounds, heteroaromatic compounds, amino acids, nucleotides, and synthetic compounds.

Development Of Affinity Microcolumns For Drug–Protein Binding Studies In Personalized Medicine: Interactions Of Sulfonylurea Drugs With In Vivo Glycated Human Serum Albumin, Jeanethe Anguizola, K. S. Joseph, Omar S. Barnaby, Ryan Matsuda, Guadalupe Alvarado, William Clarke, Ronald Cerny, David S. Hage

David Hage Publications

This report used high-performance affinity microcolumns to examine the changes in binding by sulfonylurea drugs to in vivo glycated HSA that had been isolated from individual patients with diabetes. An immunoextraction approach was developed to isolate HSA and glycated HSA from clinical samples, using only 20 μL of plasma or serum and 6–12 nmol of protein to prepare each affinity microcolumn. It was found that the affinity microcolumns could be used in either frontal analysis or zonal elution studies, which typically required only 4–8 min per run. The microcolumns had good stability and allowed data to be obtained for multiple …

Aqueous Red-Emitting Silicon Nanoparticles For Cellular Imaging: Consequences Of Protecting Against Surface Passivation By Hydroxide And Water For Stable Red Emission, Sheng-Kuei Chiu, Beth Ann Manhat, William J.I. Debenedetti, Anna L. Brown, Katye Fichter, Tania Vu, Micah Eastman, Jun Jiao, Andrea Mitchell Goforth

Chemistry Faculty Publications and Presentations

Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role …

Frozen Rotor Approximation In The Mixed Quantum/Classical Theory For Collisional Energy Transfer: Application To Ozone Stabilization, Alexander Teplukhin, Mikhail V. Ivanov, Dmitri Babikov

Chemistry Faculty Research and Publications

A frozen-rotor approximation is formulated for the mixed quantum/classical theory of collisional energy transfer and ro-vibrational energy flow [M. Ivanov and D. Babikov, J. Chem. Phys.134, 144107 (Year: 2011)]. Numerical tests are conducted to assess its efficiency and accuracy, compared to the original version of the method, where rotation of the molecule in space is treated explicitly and adiabatically. New approach is considerably faster and helps blocking the artificial ro-vibrational transitions at the pre- and post-collisional stages of the process. Although molecular orientation in space is fixed, the energy exchange between rotational, vibrational, and translational digresses of freedom still occurs, …

The Geologic Records Of Dust In The Quaternary, Daniel R. Muhs

United States Geological Survey: Staff Publications

Study of geologic records of dust composition, sources and deposition rates is important for understanding the role of dust in the overall planetary radiation balance, fertilization of organisms in the world’s oceans, nutrient additions to the terrestrial biosphere and soils, and for paleoclimatic reconstructions. Both glacial and non-glacial processes produce fine-grained particles that can be transported by the wind. Geologic records of dust flux occur in a number of depositional archives for sediments: (1) loess deposits; (2) lake sediments; (3) soils; (4) deep-ocean basins; and (5) ice sheets and smaller glaciers. These archives have several characteristics that make them highly …

Loess And Its Geomorphic, Stratigraphic, And Paleoclimatic Significance In The Quaternary, Daniel R. Muhs

United States Geological Survey: Staff Publications

Loess is aeolian silt visible in the field as a sedimentary body. It covers a significant portion of the land surface of the Earth. Loess thickness, particle size, and carbonate content decrease downwind from sources, useful trends for paleowinds. Many loess sections consist of relatively thick deposits of mostly unaltered sediment with intercalated paleosols. Paleosols represent periods of landscape stability when loess deposition slowed significantly. Loess in most regions was deposited during glacial periods and paleosols formed during interglacial periods. Loess has the potential to record the timing and environment of glacial–interglacial cycles of the Quaternary on many continents.

Reproductive Health Of Yellow Perch Perca Flavescens In Selected Tributaries Of The Chesapeake Bay, Vicki S. Blazer, Alfred E. Pinkney, Jill A. Jenkins, Luke R. Iwanowicz, Steven Minkkinen, Rassa O. Draugelis-Dale, James H. Uphoff

United States Geological Survey: Staff Publications

Reduced recruitment of yellow perch has been noted for a number of years in certain urbanized watersheds (South and Severn Rivers) of the Chesapeake Bay. Other rapidly developing watersheds such as Mattawoman Creek are more recently showing evidence of reduced recruitment of anadromous fishes. In this study, we used a battery of biomarkers to better document the reproductive health of adult yellow perch collected during spring spawning in 2007–2009. Perch were collected in the South and Severn Rivers, Mattawoman Creek and the less developed Choptank and Allen's Fresh watersheds for comparison. Gonadosomatic indices, plasma reproductive hormone concentrations, plasma vitellogenin concentrations …

Human-Caused Mortality Influences Spatial Population Dynamics: Pumas In Landscapes With Varying Mortality Risks, Jesse R. Newby, L. Scott Mills, Toni K. Ruth, Daniel H. Pletscher, Michael S. Mitchell, Howard B. Quigley, Kerry M. Murphy, Rich Desimone

United States Geological Survey: Staff Publications

An understanding of how stressors affect dispersal attributes and the contribution of local populations to multi-population dynamics are of immediate value to basic and applied ecology. Puma (Puma concolor) populations are expected to be influenced by inter-population movements and susceptible to human induced source–sink dynamics. Using long-term datasets we quantified the contribution of two puma populations to operationally define them as sources or sinks. The puma population in the Northern Greater Yellowstone Ecosystem (NGYE) was largely insulated from human-induced mortality by Yellowstone National Park. Pumas in the western Montana Garnet Mountain system were exposed to greater human-induced mortality, …

Performance Of Human Fecal Anaerobe-Associated Pcr-Based Assays In A Multi-Laboratory Method Evaluation Study, Blythe A. Layton, Yiping Cao, Darcy L. Ebentier, Kaitlyn Hanley, Elisenda Balleste, Joao Brandao, Muruleedhara Byappanahalli, Reagan Converse, Andreas H. Farnleitner, Jennifer Gentry-Shields, Maribeth L. Gidley, Michele Gourmelon, Chang Soo Lee, Jiyoung Lee, Solen Lozach, Tania Madi, Wim G. Meijer, Rachel Noble, Lindsay Peed, Georg H. Reischer, Raquel Rodrigues, Joan B. Rose, Alexander Schriewer, Chris Sinigalliano, Sangeetha Srinivasan, Jill Stewart, Laurie C. Van De Werfhorst, Dan Wang, Richard Whitman, Stefan Wuertz, Jenny Jay, Patricia A. Holden, Alexandria B. Boehm, Orin Shanks, John F. Griffith

United States Geological Survey: Staff Publications

A number of PCR-based methods for detecting human fecal material in environmental waters have been developed over the past decade, but these methods have rarely received independent comparative testing in large multi-laboratory studies. Here, we evaluated ten of these methods (BacH, BacHum-UCD, Bacteroides thetaiotaomicron (BtH), BsteriF1, gyrB, HF183 endpoint, HF183 SYBR, HF183 Taqman^®, HumM2, and Methanobrevibacter smithii nifH (Mnif)) using 64 blind samples prepared in one laboratory. The blind samples contained either one or two fecal sources from human, wastewater or non-human sources. The assay results were assessed for presence/absence of the human markers and also quantitatively while …

An Algorithmic And Information-Theoretic Approach To Multimetric Index Construction, Donald R. Schoolmaster Jr., James B. Grace, E. William Schweiger, Glenn R. Guntenspergen, Brian R. Mitchell, Kathryn M. Miller, Amanda M. Little

United States Geological Survey: Staff Publications

The use of multimetric indices (MMIs), such as the widely used index of biological integrity (IBI), to measure, track, summarize and infer the overall impact of human disturbance on biological communities has been steadily growing in recent years. Initially, MMIs were developed for aquatic communities using preselected biological metrics as indicators of system integrity. As interest in these bioassessment tools has grown, so have the types of biological systems to which they are applied. For many ecosystem types the appropriate biological metrics to use as measures of biological integrity are not known a priori. As a result, a variety of …

Controls On Recent Alaskan Lake Changes Identified From Water Isotopes And Remote Sensing, Lesleigh Anderson, Jennifer Rover, Nikki Gaulager, Jean Birks

United States Geological Survey: Staff Publications

High-latitude lakes are important for terrestrial carbon dynamics and waterfowl habitat driving a need to better understand controls on lake area changes. To identify the existence and cause of recent lake area changes in the Yukon Flats, a region of discontinuous permafrost in north central Alaska, we evaluate remotely sensed imagery with lake water isotope compositions and hydroclimatic parameters. Isotope compositions indicate that mixtures of precipitation, river water, and groundwater source ~95% of the studied lakes. The remaining minority are more dominantly sourced by snowmelt and/or permafrost thaw. Isotope-based water balance estimates indicate 58% of lakes lose more than half …

Extending Airborne Electromagnetic Surveys For Regional Active Layer And Permafrost Mapping With Remote Sensing And Ancillary Data, Yukon Flats Ecoregion, Central Alaska, Neal J. Pastick, M. Torre Jorgenson, Bruce K. Wylie, Burke J. Minsley, Lei Ji, Michelle A. Walvoord, Bruce D. Smith, Jared D. Abraham, Joshua R. Rose

United States Geological Survey: Staff Publications

Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r = 0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0–2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r = 0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101 cm) and the probability of near-surface (up to 123-cm depth) permafrost occurrence from field data, modelled near-surface (0–2.6m) resistivity, and other relevant remote sensing and map data. At site scale, the predicted ALTs were similar to those previously observed for different vegetation types. At the landscape scale, the predicted ALTs tended to be thinner on higher-elevation loess deposits than on low-lying alluvial and sand sheet deposits of the Yukon Flats. The ALT and permafrost maps provide a baseline for future permafrost monitoring, serve as inputs for modelling hydrological and carbon cycles at local to regional scales, and offer insight into the ALT response to fire and thaw processes. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

A Review Of Environmental Impacts Of Salts From Produced Waters On Aquatic Resources, Aida M. Farag, David D. Harper

United States Geological Survey: Staff Publications

Salts are frequently amajor constituent ofwastewaters produced during oil and gas production. These produced waters or brines must be treated and/or disposed and provide a daily challenge for operators and resourcemanagers. Some elements of salts are regulated with water quality criteria established for the protection of aquatic wildlife, e.g. chloride (Cl⁻), which has an acute standard of 860 mg/L and a chronic standard of 230 mg/L. However, data for establishing such standards has only recently been studied for other components of produced water, such as bicarbonate (HCO3 ⁻), which has acute median lethal concentrations (LC50s) ranging from …

Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti

United States Geological Survey: Staff Publications

Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age mega fauna was more diverse in species and possibly contained 6x more individual animals than live in the region today. Mega faunal biomass during the last ice age may have been 30x greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly …